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HomeMy WebLinkAboutMINUTES - 05022006 - C.28 TO: BOARD OF SUPERVISORS, AS GOVERNING Contra BOARD OF THE FLOOD CONTROL& WATER CONSERVATION DISTRICT Costa FROM: MAURICE M. SHIU, CHIEF ENGINEER County rA covrs'r't DATE: May 2, 2006 SUBJECT: ADOPT the Lower Walnut Creek and Lower Grayson Creek Floodplain Restoration and De-Silting Project Mitigated Negative Declaration and Mitigation Monitoring Program in compliance with the California Environmental Quality Act(CEQA);APPROVE the project and AUTHORIZE the Chief Engineer, Flood Control and Water Conservation District, or designee, to advertise the project, Concord area. (District IV) [CDD-CP# 05-30] Project No. 7520 6139353 and 7520-6119354 SPECIFIC REQUEST(S)OR RECOMMENDATION(S)&BACKGROUND AND JUSTIFICATION RECOMMENDED ACTION: FIND on the basis of the Lower Walnut Creek and Lower Grayson Creek Floodplain Restoration and De-Silting Project Mitigated Negative Declaration initial study and all comments received as well as the staff responses contained herein,that there is no substantial evidence the project will have a significant effect on the environment, and ADOPT the Mitigated Negative Declaration and Mitigation Monitoring Program in compliance with the (the custodian of which is .the Community Development Department Director who is located at 651 Pine Street, Martinez), and DIRECT the Director of Community Development to file a Notice of Determination th! the County Clerk, and Continued on Attachment: SIGNATURE: l B RECOMMENDATION OF COUNTY ADMINISTRATOR ❑ RECOMMENDATION OF BOARD COMMITTEE [APPROVE 2NOTHER SIGNATURE(S): ACTION OF BO R ON G APPROVED AS COMMEN OTHER ❑ I hereby certify that this is a true and correct copy of an action taken and entered on the minutes of the Board of Supervisors on VOT OF SUPERVISORS the date shown. UNANIMOUS(ABSENT AYES: NOES: ATTESTED: Da��. Zt'e ABSENT: ABSTAIN: _eyJOHN CULLEN,C)w(of the Board of Supervisors and County CD:ms Administrator G:\GrpData\EngSvc\ENVIRO\BO\2006\(05-2-06)CEQAWalnut Gray.doc Orig.Div:Public Works(Environmental Section) - Contact: Carrie Dovzak,(313-2190) By �' '' , Deputy cc: Administrator—Atm.E.Kuevor Auditor-Controller " Community Development—H.Li Public Works: Construction—P.Edwards Flood Control—P.Detjens Environmental—C.Dovzak Environmental Checklist Form 1. Project Title: Lower Walnut Creek and Lower Grayson Creek Floodplain Restoration and De-Silting Project 2, L6ad Agency Name and Address:, Contra Costa County Community Development Department 651 Pine Street, North Wing - 4th Floor Martinez, CA 94553 3. Q-)ntact Person and Phone Number: Carrie Dovzak, Planner If (925) 313-2190 Contra Costa County Public Works Department 255 Glacier Drive ' Martinez, CA 94553 4. Project Location: The project is located iri unincorporated Contra Costa County, the City of Concord, and the City of Pleasant Hill.' Lower Walnut Creek and Lower Grayson Creek. (Figures 1 and 2.) 5. Project Sponsor's Name and Address: Contra Costa County Public Works Dept. 255 Glacier Drive Martinez, CA 94553 6. General Plan Designation: Multiple: Open Space, PS 7. Zoning: Public/Semi-public j 8. Description of Project: i The project consists of floodplain restoration and de-silting excavation work in the floodplains of Lower Walnut. j Creek between Concord Blvd. and Drop Structure 1 (below Monument Blvd.), and Lower Grayson Creek from { Highway 4 to Chipancingo Pkwy.). The low flow channel in both creeks will not be impacted during the ! excavation work, and will be protected by a two-foot berm/ buffer zone that will be flagged prior to start of construction. Identified non-wetland areas in Walnut Creek, and wetland areas in Lower Grayson Creek will be excavated to restore the flood plain to design elevations. Lower Walnut Creek and Lower Grayson Creek were engineered from narrow creek corridors into trapezoidal channels in the early 1960's to provide flood control for the cities and property owners along its corridor, and to expedite floodwaters from the upper watershed to the Sacramento River. Several reaches were de-silted in 1993,'1995 and 1997, and have, since then, exceeded their capacity for flood control from silt deposits on their flood plains. The desilting planned will restore the flood control capacity of the channels. A CCC Flood Control and Water Conservation District (District) right of way, including District access roads, exist on both sides of the channels. i t The project lies within unincorporated Contra Costa County, The City of Pleasant Hill, and the City of Concord. Real Property transactions may be necessary in support of this project. j I I i 9. Surrounding Land Uses and Setting: Lower Walnut Creek and Lower Grayson Creek flow through a variety of land use, but the predominant land uses along the corridors are commercial and industrial. The commercial properties range from shopping centers and box stores, to landfills, and an airport. While the largest percentage of land use is the airport, mixed commercial and industrial uses are also prevalent. A small percentage of the land use is single family residential housing. See Figure 2. 10. Other public agencies whose approval U. S.Army Corps of Engineers, SF District of the Regional (e.g., permits, financing approval, Or water Quality Control Board, California Department of Fish and Game participation agreement). Page 1 of 19 j I r; �f i ENVIRONMENTAL FACTORS POTENTIALLY AFFECTED: ' The environmental factors checked below would•be potentially affected by this project, involving at least one impact that is a "Potentially Significant Impact" as indicated by the checklist on the following pages. Land Use & Planning X Transportation/Circulation Public Services Population & Housing X Biological Resources Utilities &Service ` kw Systems t s' Geological Problems Energy& Mineral Resources Aesthetics X Water X ' Hazards. Cultural Resourcesi Air Quality Noise Recreation ' Fr Mandatory Findings of No Significant Impacts , Significance Identified DETERMINATION, " ` On the basis of this initial evaluation: j find that the proposed project COULD NOT have a significant effect on`the,environment, and a NEGATIVE (' s DECLARATION will be prepared. I find that although the proposed project could have a significant effect on the environment, there will not be as x significant effect in this case because the mitigation measures described_on an attached sheet have been X. added to the project. A MITIGATED NEGATIVE DECLARATION will be prepared.,. ." I find that the proposed project MAY have a significant effect on the environment, and an ENVIRONMENTAL j IMPACT REPORT is required. pp' I find that the proposed project MAY have a significant effect(s) on the environment, but at least one effect (1) I has been adequately analyzed in an earlier document"pursuant to applicable legal standards, and (2) h'as been addressed by mitigation measures based on the earlier analysis as described on attached sheets, if the effect is a "potentially significant impact" or "potentially significant unless mitigated." An ENVIRONMENTAL IMPACT REPORT is.reguired, but it must analyze only the effects that remain to be addressed. - rfi find that although the proposed project could have a significant effect on the environment, there WILL NOT be s' a significant effect in this case because all potentially significant effects (a) have been analyzed adequately in ' an earlier EIR pursuant to applicable standards and (b) have been avoided or mitigated pursuant to that earlier EIR, including revisions or mitigation measures that are imposed upon the proposed project: . i signature ,Date ' �• Contra Costa County gin: Community Development Department i Print Name kL ! I 1 Y c 4 Page 2 of 19 r, f i i I SOURCES In the process of preparing the Checklist and conducting the evaluation, the following references (which are available for review at the Contra Costa County Community Development Department, 651 Pine Street 5th Floor-North Wing, Martinez)were consulted: 1. Contra Costa Resource Mapping System - Quad Sheet Panels — Vine Hill—Walnut Creek 2. The (Reconsolidated) County General Plan (July 1996) and EIR on the General Plan (January j 1991) 3. Contra Costa County Important Farmland Map 2002, California .Department of Conservation Division of Land Resources Protection 4. Field reviews by Public Works staff, Biosearch, Entrix, Natural Resouces Management, Jones and Stokes, ACOE and/or Project Description (including coordination with Design Engineer) 5. Data Summary Report for the Baseline Surveys of Anadromous Fish Habitat in Lower Walnut Creek, Contra Costa County, CA (with 11 X 17 maps) Jones and Stokes, 2004. 6. Data Collection Plan for Baseline Surveys of Anadromous Fish Habitat, and Draft Delineation of Waters of the United States, Including Wetlands, for the Lower Walnut Creek Channel Restoration Project, Concord, California —January 2005 (with 11 X 17 maps) Jones and Stokes, 2004. 7. Wildlife Habitat Assessment for the Lower Walnut Creek Channel Restoration Project — December 2004 (NRM, January 2005). i 8. Botanical Report for the Lower Walnut Creek Channel Restoration Project (with 11 X 17 maps) (Jones and Stokes, January 2005). 9. Delineation of Waters of the United States, Including Wetlands for the Lower Walnut Creek Channel Restoration Project Report. ACOE File number 29296S (NRM/Jones and Stokes, July 2004). I 10. Contra Costa County Soils Report, Soil Conservation Service, 1977. 11. Grayson Creek Habitat Assessment—August 2005, Entrix, Inc. Walnut Creek, CA. 12. Lower Grayson Creek Project Wetland Delineation —August 2005. ACOE File number 29898S. (Preliminary jurisdictional determination) Entrix, Inc. Walnut Creek, CA. I 13. ABAG Earthquake Liquefaction Maps 2001. http://www.abag.ca.gov/bayarea/eamaps 14. Towill, Inc. (2004) Topographic data and digital orthophotography of Lower Walnut Creek and Lower Grayson Creek. 15. National Marine Fisheries Service— Central Valley Chinook Salmon Essential Fish Habitat— Fall i Run. http://swr.nmfs.noaa.pov/fall.htm 16. Map: Survey Results of post-12/31/05 storm. Water surface elevation in channels. I � i I I Page 3 of 19 i EVALUATION OF ENVIRONMENTAL IMPACTS: Potentially ! Significant f Potentially Unless Less than { "Significant Mitigation Significant j Impact Incorporation Impact No Impact I i I. AESTHETICS. Would the proposal: l a. Have a substantial adverse effect on a scenic vista? X b. Substantially damage scenic resources, including, but not limited to, trees, rock, i outcroppings, and historic buildings within a state scenic highway? X I c. Substantially degrade the existing visual -character or quality of the site and its surroundings: X d. Create a new source of substantial light or glare, which would adversely affect day or 4 nighttime views in the area? X SUMMARY: Less than Significant Lower Walnut Creek and Lower Grayson Creek channels were designed to provide flood protection for low j lying areas adjacent to and surrounding the channels in the early 1960's. The trapezoidal channels were designed void of riparian cover and vegetation to expedite flood waters through the channel to the Sacramento River. Routine maintenance of the channels keeps the channels clear of mature vegetation. Construction activities will be visible to residents living adjacent to Lower Grayson Creek channel in areas adjacent to Buchanan Airport, and south of Pacheco Blvd.; however, constructionis temporary and is not expected to cause significant aesthetic impacts. The majority of the landuse in the project area is industrial and commercial. All disturbed areas will be hydro-seeded with a seed mix that includes native grasses. Construction activities are not expected to occur at night, therefore, supplemental lights will not be necessary. Following construction, the project site is expected to return to,pre-project;vegetated condition. Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact ll. AGRICULTURAL RESOURCES. In determining whether impacts to agricultural resources are ' significant environmental effects, lead agencies may refer to the California Agricultural Land Evaluation and Site Assessment .Model (1997) prepared by the California Dept. of Conservation as an optional model to use in assessing impacts on agricultural and farmland. Would the project: a. Convert Prime Farmland, Unique Farmland, or Farmland of Statewide, Importance (Farmland), as shown on the maps prepared pursuant to the Farmland Mapping and Monitoring Program of the California Resources Agency, to non- . agricultural use? X b. Conflict with existing zoning for agricultural use, or a Williamson Act contract? X c. Involve other changes in the existing X Page 4'of 19 i Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact environment, which, due to their location or nature, could result in conversion of Farmland, to non-agricultural use? SUMMARY: No Impact. The project will not affect any locally or statewide important farmland. The land immediately adjacent to the project consists of roadways, commercial properties, and industry. The Contra Costa County Important Farmland Map (FMMP, 2002) identifies the majority of the project as being within an area designated as "urban and built up land. The proposed project area is not currently used for agricultural purposes. Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact i NI. AIR QUALITY. Where available, the significance criteria established by the applicable air. quality management or air pollution control district may be relied upon to make the following determinations. Would the project: a. Conflict with or obstruct implementation of the applicable air quality plan? X b. Violate any air quality standard or contribute to an existing or projected air quality violation? X ,c. Result in a cumulatively considerable net increase of any criteria pollutant for which the project region is non-attainment under an applicable federal or state ambient air quality standard (including releasing emissions which exceed quantitative thresholds for ozone precursors)? X d. Expose sensitive receptors to substantial pollutant concentrations? X e. Create objectionable odors affecting a substantial number of people? X SUMMARY: Less Than Significant Impact. Short-term emissions and objectionable odors may be generated during construction; however, they will be minor and temporary. To minimize impacts due to construction activities, contract specifications will stipulate the use of properly tuned and muffled equipment and the elimination of unnecessary idling of equipment when not in use. Implementation of dust control practices including general watering of exposed areas will be utilized to minimize air quality impacts. The minor temporary deterioration of ambient air quality during construction will end once construction is completed; therefore, there will be no potentially adverse long-term impacts to air quality. i I I Page 5 of 19 Potentially Significant Potentially Unless Less than Significant .[ Mitigation Significant Impact 'I Incorporation. Impact No Impact IV. BIOLOGICAL RESOURCES. Would the project: a. Have a substantial adverse effect, either directly or through habitat modifications, on any species identified as a candidate, sensitive, or special status species in local or regional plans, polices, or regulations, or by the California Department of Fish and Game or U.S. Fish and Wildlife Service? X `r b. Have a substantial adverse effect on any riparian habitat or other sensitive natural community identified in local or regional plans, policies, regulations or by the California Department of Fish and Game or US Fish and Wildlife Service? X c. Have a substantial adverse effect on federally protected wetlands as defined by Section 404 of the Clean Water Act (including, but not limited to, marsh, vernal pool, coastal, etc.) through direct removal, filling, hydrological interruption, or other means? X d. Interfere substantially with the movement of any native resident or migratory fish or wildlife species or with established native resident or migratory wildlife corridors, or impede the use of native wildlife nursery sites? X e. Conflict with any local policies or ordinances protecting biological resources, such as tree preservation policy or ordinance? X f. Conflict with the provisions of an adopted Habitat Conservation Plan, Natural Community Conservation Plan, or other approved local, regional, or state habitat conservation plan? X SUMMARY: Potentially Significant Unless Mitigation Incorporated. Various studies in support of,biologicaI resources in the project area were carried out from 2003 — 2006 which identified listed species and habitats within or adjacent to the project area that need special consideration. A Habitat Assessment of the Lower Walnut Creek project site was conducted by Natural Resources Management (Berkeley,CA), in May 2004 to characterize the habitats present here and the .likelihood of special status species occurring in the area. Similarly, a biological assessment was completed by Jones and Stokes (January, 2005). A Section 404 Clean Water Act Jurisdictional Delineation was conducted by Jones and Stokes in May 2004 and confirmed by the United States Army Corps of Engineers (USACOE) on January 21, 2005 (Corps File No. 29296S). Similar wetland and habitat studies were carried out on Lower Grayson Creek by Entrix, Inc. in August 2005. A Section 404 Clean Water Act Jurisdictional Determination was confirmed on the Lower Grayson Creek (Corps File No. 29898S) area on January 3, 2006. A wetland delineation of Lower Grayson Creek between Pacheco Blvd. and Chilpancingo Pkwy. is currently in progress. Activities associated with the project will occur within California Department of Fish and Game, Regional Water Quality, Control Board, and U.S. Army Corps of Engineer's jurisdiction. Permits for the project will be obtained from these agencies. Page 6 of 19 Based on the limited habitat in the channels, and the proximity to the surrounding urban area, impact to listed species as a result of the project is unexpected. Consultants for the project have identified species that may have potential of occurrence in the project area: California red-legged frog (Rana aurora draytonii), Western pond turtle (Clemmys marmorata), Central Valley Fall run Chinook salmon and various species of birds and special status bats. Special Status Wildlife and Species of Concern California Red legged frog Based on observations by wildlife consultants working on the habitat assessments, there is a low potential for RLF habitat in the project area due to the urbanization of the area, and the presence of various predatory species identified in the creek surveys. In addition, since riparian habitat is lacking, there is limited cover for red-legged frog. Review of the CNDDB indicates the closest known sitings of RLF is approximately 5 miles away in the Martinez Hills (west), and 5 miles east in the foothills of the Mt. Diablo Watershed. These habitats are not connected to the Walnut Creek/ Grayson Creek watersheds and are separated from the project site by extensive urban and industrial landuse. Large numbers of predatory,species (including mosquito fish, crayfish and bullfrogs) have been identified in portions of Walnut and Grayson Creeks as well. For these reasons RLF are not expected to be impacted by the project. Western Pond Turtle The Western Pond Turtle is a federal and state species of concern, and is a California Fully Protected species. No occurrences of western pond turtle were observed during the habitat survey, nor are observed within 5 miles of the project site according to the CNDDB database. However, suitable habitat for the species may occur at the project site along Grayson Creek, where cattails provide cover near side channels. If any western pond turtles are found during construction, they will be relocated to an area not subject to disturbance. Mitigation Bio - 1: If any western pond turtles are found during construction, they will be relocated to an area not subject to disturbance. Birds Since the project site covers a large area, there is potential for birds to forage or nest in the site during various times of the year. Special Status birds identified as having the potential to be in the general area include California black rail, Suisun Song Sparrow, Salt Marsh Yellow Throat, White-tailed Kite and Loggerhead Shrike. Birds that prefer the Salt Marsh-environment (Clapper Rail, Suisun song sparrow and Salt Marsh I Yellow Throat) would prefer the northern tidally influenced portion of Lower Walnut Creek, where there are { large expanses of pickleweed and tidally effected marsh land. This area is not in the project area, and no tidal fI marsh habitat will be impacted by the project. Landuse in the project area is predominantly urban. The (C channels are bordered by shopping malls, hotel complexes and dense commercial real estate. To avoid impact to nesting birds in the project area, avoidance and minimization measures will be ` implemented including, timing construction during the late summer, and at the end of the breeding window for I these special status birds. Mitigation 'Bio - 2: Construction will avoid breeding season for nesting birds. Construction activities will occur in late summer in order to ensure that impacts to sensitive bird species are minimized. I Nesting raptors j Tall trees adjacent to the access roads'above the Lower Walnut Creek Channel may be the site of nesting raptors. Avoidance and minimization measures used for nesting birds will be extended to raptor nests found near the project site. There are no mature trees in the project area that will be affected by the de-silt operation. Most mature trees near the project area are-part of landscaping for nearby malls, and parking areas which are heavily impacted by human and automobile traffic. r j Page 7 of 19 1 i Mitigation Bio - 3: Same as Mitipation Bio 2: C Special-status Bat Species Several species' of bats that are Federal Species of Concern may roost in bridges and nearby buildings adjacent to both .Lower Grayson Creek and Lower Walnut Creek. There are four road overpasses in the project area. Suitable foraging habitat occurs adjacent to both creeks, but it will not be affected by construction. Project construction will occur outside of the breeding',times for bat species. If special.status bat species are identified during construction, the District will work,with the bat specialist, as well as the'California Department of -Fish and Game, to ensure the species are adequately protected. Currently there are no speciakstatus bat species listings in the CNDDB in the project vicinity. ` Fall run Chinook Salmon f Since both creek corridors have been identified as possible migration routes and spawning sites for Chinook salmon, studies were carried out to identify stream characteristics in relation to spawning and rearing habitat for this protected species (Jones and Stokes, 2004, 2005. Entrix, 2005). Central Valley:Fall Chinook have been observed migrating up the Walnut Creek Channel,from the Sacramento River in late Fall. The District has co-sponsored several ongoing studies with ACOE (Sacramento) to assess habitat quality, and spawning success (viability of redds and eggs) in the Walnut Creek channel from the ! i Sacramento River to the first major migration barrier (Drop #1). Although the Walnut Creek channel continues to support migration and spawning of adult Chinook salmon. the diversity and complexity'of channel habitat in j Lower Walnut Creek is low. i h The de-silting project will occur before.the Fall migration up Walnut;Creek channel begins, therefore there will j be no salmon present during the time period of the project. The project work will occur in the dry season and avoid the stream channel. Avoidance and minimization measures to avoid impact to the stream channel, and re-establish vegetation in the flood plain after the desilt, will be implemented. These include 1) establishing a two-ft. buffer,(berm) around the perimeter of the stream channel,, ponds and selected wetlands during the j project .construction 2) construction will occur before the migration window for Fall Chinook occurs 3) equipment will be .properly maintained to ensure deleterious fluids are not allowed to enter the creek (or floodplain area), 4) work will be conducted during the dry season of any given year. For these reasons, no impacts to salmonids are expected as a result of the project. Mitigation Bio - 4: Construction will avoid the,low flow channel completely'in the Lower Grayson Creek and j Lower Walnut Creek channels. Mitigation Bio - 5: Construction will not occur during the migration window for Fall run Chinook salmon; construction will occur during the dry season. Mitigation Bio — 6: A two-ft berm/barrier will be left between sensitive wetland areas in Lower Walnut Creek and construction areas. This berm will delineate the construction areas from sensitive habitat; and will prevent impact to identified habitat. Wetlands 8 An ACOE confirmed wetland delineation has been completed for the Lower Walnut Creek project area (Corps File No: 29296S), and the Lower Grayson Creek (Corps File No.298980S) project area. A wetland,delineation of Lower Grayson Creek between Pacheco Blvd. and Chipancingo: Pkwy. is currently in progress. Areas of seasonal'wetlands and emergent marsh, as well as 'Other Waters of the U.S. ' (the low flow channel and ponds) were delineated in the project area under ACOE jurisdiction. Large areas of non-wetland, were also delineated. I Page 8 of 19 A considerable amount of silt has been deposited in the Lower Walnut Creek channel since the last de-silting operation in 1997, and areas of upland within the corridor have increased. These areas were identified in the ACOE wetland confirmation as `non-wetland' (Jones and Stokes, 2005), and will be removed as part of the project to restore flood capacity within the channel. Non—wetland areas are dominated by ruderal species such as ripgut brome, black mustard, Italian thistle, Bermuda grass and slender wild oats. Identified wetland areas within the Lower Walnut Creek channel will be protected during the de-silting operation, as will the low flow stream channel and ponds. This will leave valuable habitat intact. A two-ft buffer zone around wetland areas will ensure that sensitive areas are isolated from construction activities. Similar wetland conditions exist in the Lower Grayson corridor between 1-680 and Pacheco Blvd., and these wetlands are also within US Army Corps of Engineer's jurisdiction. Since the channel is narrower here than in Walnut Creek, and the floodplain does not exhibit upland areas of non-wetland, excavation will involve desilting within the seasonal wetlands to return the channel to design capacity. This impact will be temporary as the excavated areas of wetland here will be returned to elevations conducive to the re-establishment of perennial wetlands. The project has been specifically designed to be self-mitigating: .temporary impacts to wetlands within Grayson Creek due to the desilting will be compensated for in two ways: 1) avoidance of existing wetlands on Walnut Creek and 2) reestablishment of�wetlands on both Walnut Creek and Grayson j Creek. 1) Avoidance of existing wetlands: Desilting activities within Lower Walnut Creek have been designed to avoid impacts to existing wetlands. Temporary flagging with tape will be installed around wetland areas, the low flow channel, and ponded . areas to delineate a two foot buffer zone/berm to isolate sensitive areas from impacts during construction. No wetland areas will be impacted by the desilting activities on Walnut Creek with the exception of 0.1 acre of temporary impact due to access road installation. ! r 2) Reestablishment of wetlands Approximately 7. acres of. non-wetland areas in the Lower Walnut Creek channel will be lowered to an elevation appropriate for the stream channel that is expected to support the re-establishment of perennial wetlands. Wetland areas in the Lower Grayson Creek channel will be desilted to a similar elevation, also ultimately converting the entire area into perennial wetlands. These mitigation measures will be implemented in coordination with the Army Corps of Engineers and San Francisco Bay Regional Water Quality Control Board (see attached Appendix A: Mitigation Monitoring Plan). f County staff will coordinate with staff from the resource agencies regarding the project, and the appropriate j agreements and permits will be obtained prior to implementation of the project. The County will comply with all conditions negotiated during the permit acquisition process. County staff is currently applying for coverage under Corps' Nationwide permit program under Section 404 of the Clean Water Act. I Mitigation Bio— 7. See Mitigation Bio — 6 above. j Mitigation Bio — 8: The project is designed to be self mitigating. Exisiting wetland areas in Walnut Creek will be specifically avoided by the project and areas of non-wetland in the Walnut Creek channel will be lowered to an elevation more conducive to re-establishment of perennial wetlands, compensating for the temporary impact to wetlands in Lower Grayson Creek. Wetlands impacted within Lower Grayson Creek i are expected to recover rapidly as evidenced by past de-silting projects in this creek. Potentially Significant Potentially Unless Less than i Significant Mitigation Significant Impact Incorporation impact No Impact V. CULTURAL RESOURCES. Would the project: a. Cause a substantial adverse change in the X Page 9 of 19 I I Potentially Significant Potentially ' Unless Less than Significant Mitigation Significant Impact 1 Incorporation ' Impact No Impact significance of a historical resource as f defined in §15064.5? I( b. Cause a substantial adverse change in the f significance of an archaeological resource I pursuant to §15064.5? ; X c. Directly or indirectly destroy a unique j paleontological resource or.site or unique geologic feature? i X d. Disturb any human remains, including those interred outside of formal cemeteries? X • r SUMMARY: Less Than Significant Impact. The channels were originally excavated in the early,1960's, and most recently desilted in 1993, 1995 and 1997. Project specifications for the de-silting work will not allow excavation below the design level for the channel; therefore all areas that will be disturbed by the project have been previously impacted, and new findings of in-situ archaeological importance are not anticipated. Standard construction contract specifications for the project will ';include measures related to discovery of cultural resources, including informing personnel connected with the project of the possibility of finding archaeological and/or historical resources, requiring notification of the Resident Engineer in the event of a discovery, and retention of a cultural resources consultant to provide assistance in the event of a discovery. In addition, the Resident Engineer for the project will receive instruction regarding identification of archaeological and historical resources in the field. In particular, the specifications will require work to be halted in the event t of an archaeological discovery within 85 feet of the discovery. An archaeological consultant shall be contacted and he/she shall inspect the site before advising the resident engineer to authorize further work. } Potentially i Significant Potentially Unless Less than Significant Mitigation Significant Impact ; Incorporation Impact No Impact VI. Geology and Soils. Would the project: a. Expose-people or structures to potential I substantial adverse effects, including the risk of, I loss, injury, or.death involving: 1. Rupture of a known earthquake fault, as delineated on the most recent Alquist-Priolo Earthquake Fault Zoning Map issued by the I State Geologist for the area or based on other substantial evidence of a known fault? Refer to Division of Mines and Geology Special Publication 42. j X . 4 2. Strong seismic ground shaking? I X 3. Seismic-related ground failure, including liquefaction? X 4. Landslides? X b. Result in substantial soil erosion or the loss of topsoil? X c. Be located on a geologic unit or soil that is unstable, or that would become unstable as a. result of the project, and potentially result in.on- or off-site landslide, lateral spreading, subsidence, liquefaction or collapse? X d. Be located on expansive soil, as defined in Table 18-1-B-of the Uniform Building Code X Page 10 of 19 11 oili I I Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact (1994), creating substantial risks to life or property? e. Have soils incapable of adequately supporting the use of septic tanks or alternative waste disposal systems where sewers are not available for the disposal of wastewater? X SUMMARY Less Than Significant Impact. Exposure of people or property to geologic.hazards is not expected to increase as a result of the project. Grading and excavation associated with the channel maintenance will result in a minor change in topography in the channel, and temporarily increase,the exposure of soils to wind erosion. However, this is a less than significant and temporary impact. Adherence to standard dust control and erosion control practices, including, but not limited to, general watering of exposed areas will minimize impacts. Contract specifications will require flagging a two foot berm/buffer zone between the limits of excavation and identified sensitive wetlands and other waters of the U.S.' to prevent soil from these areas during construction activities. These measures will be incorporated into the construction contract. De-silting of the project area will not result in unstable earth conditions or change geologic substructures. Exposure of people or property to geologic hazards is not expected to occur as a result of the project. In order to stabilize exposed soils, all areas left exposed due to the de-silting work will be hydro-seeded with a mix that includes native grasses, at the earliest practicable date. Hydro-seeding will stabilize the exposed sediment in the floodplain until vegetation is naturally established. Vegetation in the floodplain is expected to establish quickly, as it has in past de-silting operations. jI I Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact VII. HAZARDS AND HAZARDOUS MATERIALS. Would the project: j a. Create a significant hazard to the public or the environment through the routine transport, use, or disposal of hazardous materials? X b. Create a significant hazard to the public or the environment through reasonably foreseeable upset and accident conditions involving the.. release of hazardous materials into the environment? X c. Emit hazardous emissions or handle hazardous or acutely hazardous materials, substances, or waste within one-quarter mile of an existing or proposed school? X d. Be located on a site which is included on a list of hazardous materials sites compiled pursuant to Government Code Section 65862.5 and, as a result, would it create a significant hazard to the public or the environment? X e. For a project located within an airport land use plan or, where such a plan has not been adopted, within two miles of a public airport or X Page 11 of 19 i Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impacts Incorporation Impact No Impact public use airport, would the project result in a safety hazard for people residing or working in the project area. f. For a project within the vicinity of a private airstrip, would the project result in a safety I hazard for people residing or working in the project area? X g. Impair implementation of or physically interferes with an adopted emergency response plan or , emergency evacuation plan? X h. Expose people or structures to a significant risk of loss, injury or death involving wildland fires, including where wildlands are adjacent to 1 urbanized areas or where residences are intermixed with wildlands? ( X SUMMARY: Potentially Significant Unless Mitigation Incorporated. Sediments deposited on the floodplain of Lower Walnut Creek, and Lower Grayson Creek may have the potential to contain hazardous materials (such as concentrations of metals or hydrocarbons) that could pose a threat to the surrounding environment if not handled, or disposed of properly. The District will create a soil sampling plan that will represent various points throughout the project area where the floodplain will be4de-silted.'The current plan for the excavated material entails transporting it to the nearby Tesoro Refinery and stockpiling the sediment in on upland location (Figure 2.). Soil samples will be analyzed at a certified laboratory for'various'constituents identified by Tesoro Refinery before they will accept the soil for disposal. If Tesoro Refinery cannot accept the soil, it will be properly managed and disposed of at a licensed facility. i The project has the potential to release hazardous substances, such as accidental petroleum spills from equipment, during construction. Per the contract specifications, standard construction safety practices will be followed.during construction to ensure no accidental release of hazardous substances occurs and no increase in the potential for exposure to these substances occurs. There are 4 road crossings above the channel that may,contain utility lines. Project designs will identify these utility and road crossings so that their locations can be clearly marked in the field, and avoided by construction activities. No interference with an emergency evacuation or response is expected to result from the project. Traffic control measures near the work area will minimize the potential for accidents. Maintenance roads parallel the project site at both creeks, enabling-maintenance vehicles to avoid public thoroughfares during the excavation work. j Mitigation HAZ-1: Representative soil samples will be collected at locations throughoutr the project area, and analyzed for a variety of constituents at a local state certified laboratory. The samples will be ; assessed of their contents before transportation to, and stockpiling at the nearby Tesoro Refinery site or a licensed facility. Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact i Incorporation Impact No Impact VIII. HYDROLOGY AND WATER QUALITY. Would the project: ' a. Violate any water,quality standards or waste, discharge requirements? X Page 12 of 19,; i 4 Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact b. Substantially deplete groundwater supplies or interfere substantially with groundwater recharge such that there would be a net deficit in aquifer volume or a lowering of the local groundwater table level (e.g., the production rate of pre-existing nearby wells would drop to a ! level which would not support existing land uses or planned uses for which permits have been granted)? X c. Substantially alter the existing drainage pattern of the site or area, including through the alteration of the course of a stream or river, in a manner, which would result in substantial erosion or siltation on or off-site? X d. Substantially alter the existing drainage pattern of the site or area, including through the alteration of the course of a stream or river, or substantially increase the rate or amount of surface runoff in a manner, which would result in flooding on- or off-site? X e. Create or contribute runoff water which would exceed the capacity of existing or planned storm water drainage systems or provide substantial additional sources of polluted runoff? X f. Otherwise substantially degrade water quality? X g. Place housing within a 100-year flood hazard area as mapped on a federal Flood Hazard Boundary or Flood Insurance Rate Map or other flood hazard delineation map? X h. Place within a 100-year flood hazard area structures, which would impede or redirect flood flows? X i. Expose people or structures to a significant risk of loss, injury or death involving flooding, including flooding as a result of the failure of a levee or dam? X j. Inundation by seiche, tsunami, or mudflow? X SUMMARY: Potentially Significant Unless Mitigation Incorporated. Avoidance and minimization.measures will be undertaken in the design of the project to avoid adverse impacts to water quality. Contract specifications will require these measures to be implemented to ensure that sediment will not enter the waterway. A two-ft l berm/buffer will be flagged around the low flow channel of both channels. The excavation project will not adversely affect the quantity or quality of surface water, ground water or public water supply. Contract specifications will also require the storage, servicing and fueling of construction equipment outside of the channel. Standard construction safety practices will be incorporated into the project to reduce the possibility of a spill of gasoline, oil, or other pollutant that could have a significant impact on water quality. In addition, sediment will be loaded on to dump trucks, and deposited at an upland site chosen at the nearby Tesoro Refinery (Figure 2.). Normal creek flows will be maintained during the desilting project, so a de- I , watering system will not be needed. j The low flow channel will not be impacted by the excavation project, therefore no change in drainage patterns are expected. Excavation of silt deposits from the flood plain will allow the low flow channel to use it's flood plain more efficiently during high flow. The project will not create run-off of any kind to the channel, as Page 13 of 19 I, i° vegetation is expected to re-establish itself quickly after the desilt. Project work will occur at the driest part of the year. The excavation project will not increase exposure of people or property to flooding. In fact, the .goal of the project is to lessen the potential exposure of people and property to flooding by restoring the flood control channel to design capacity. Total disturbance due to this project will be greater than an acre; therefore, in order to comply with the State Water Resources Control Board National Pollutant Discharge Elimination System (NPDES) General Construction Permit requirements, a Storm Water Pollution Prevention Plan (SWPPP) will be required by the contract plans and specifications. The SWPPP will specify the Best Management Practices that will be used during project construction to ensure water quality impacts are minimized. The SWPPP will address erosion control, sediment control, non-stormwater management,- post-construction storm water management, and maintenance, inspection, and repair of the BMPs used on-site. At;the completion of the,project; all disturbed areas will be stabilized through the use of hydro-seeding with a mix lincluding native grasses. Water Quality Certification will be obtained from the San Francisco Bay Regional Water Quality Control Board (SFBRWCB) prior,.to construction of the project. Special conditions required by the certification will be complied with during construction in order to minimize the possibility of water quality impacts. Mitigation Hvdro - 1: A two-ft berm/barrier will be left between the low'flow channel and construction areas in both Lower Walnut Creek and Lower Grayson. This berm will prevent sediment from entering the creek during construction, and affecting water quality. C I Potentially Significant Potentially Unless Less than i Significant Mitigation Significant , k' Impact Incorporation Impact No Impact IX. LAND USE AND PLANNING. Would the project: a. Physically divide an established community? f X b. Conflict with any applicable land use plan, policy, or regulation of an agency with jurisdiction over the project (including, but not limited to the general plan, specific plan, local coastal program, or zoning ordinance) adopted I f for' the purpose of avoiding or mitigating an C environmental effect? i X c. Conflict with any applicable habitat conservation plan or natural community conservation plan? X i SUMMARY: No Impact. The project will not result in an alteration of the present or planned'land use of the area. Potentially Significant Potentially Unless Less than j Significant Mitigation Significant Impact Incorporation Impact No Impact X. MINERAL RESOURCES. Would the project: a. Result in the loss of availability of a known' ; mineral resource that would be of value to the , I region and the residents of the state? X b. Result in the loss of availability of a locally' important mineral resource recovery site delineated on a local general'plan, specific plan' or other land use plan? X - j Page 14 of 19 t NIIIIIIIIIIIIIIIIIIIIIIIIIIII'­ 11i I SUMMARY: No impact. The construction of the project would not involve quarrying, mining, or extraction of any known regionally or locally important mineral, oil, or gas resources on site, nor would it deplete any non- renewable natural resource. Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact XI. NOISE. Would the project result in: a. Exposure of persons to or generation of noise levels in excess of standards established in the local general plan or noise ordinance, or applicable standards of other agencies? X b. Exposure of persons to or generation of excessive ground borne vibration or ground borne noise levels? X c. A substantial permanent increase in ambient noise levels in the project vicinity above-levels existing without the project? X d. A substantial temporary or periodic increase in f ambient noise levels in the project vicinity above j levels existing without the project? X f e. For a project located within an airport land use plan or, where such a plan has not been adopted, within two miles of a public airport or public use airport, would the project expose people residing or working in the project area to excessive noise levels? X f. For a project within the vicinity of a private airstrip, would the project expose people f residing or working in the project area to excessive noise levels? X j SUMMARY: Less Than Significant Impact. Maintenance of the flood control channel will not increase the capacity of roads in the vicinity; therefore no additional vehicle trips will be generated as a result of the i implemented project. There will be a limited number of additional vehicle trips during construction resulting from worker vehicles accessing the site; however, this will be a minor and temporary impact that would not significantly increase the ambient noise level at the project site and is, therefore, deemed less than significant. The site is bordered predominantly by commercial and industrial properties, including an airport. Construction of the project will increase the ambient noise level near the project site temporarily. Typically, f construction activities produce average noise levels of about 86 dBA at 50 feet from any given construction ` site. This construction project is expected to be consistent with this generalized average due to the standard construction activities that will occur. Increased noise as a result of construction activities will be temporary and will; therefore, remain at a level that is less than significant. Working hours will be limited to 7:30 am to 5 pm on weekdays. These working hours will be incorporated as part of the construction contract. Contract specifications will also require the use of properly tuned and muffled equipment to minimize noise due to construction activities. I The majority of the project area is commercial with high traffic flow into and out of shopping malls, and other commercial buildings. 1-680 and Highway j4, both major freeways, are located next to the project area. The project will not add any noticeable noise to the area. I ( Page 15 of,19 � I I i i [f[ I f j Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact i Incorporation Impact No Impact ' t i XII. POPULATION AND HOUSING. Would the project: I a. Induce substantial population growth in an area, either directly (for example, by proposing new homes and businesses) or indirectly (for ! example, through extension of roads or other infrastructure)? X b. Displace substantial numbers of existing housing, necessitating the construction of replacement housing elsewhere? X c. Displace substantial numbers of people, j necessitating the construction of replacement housing elsewhere? ! X SUMMARY : No impacf. The goal of the project is to provide flood control protection to the area. This goal will be achieved without creating additional infrastructure that could encourage population growth. Downstream of the proposed flood control improvements (the location the project will benefit), the area is essentially built-out with industrial uses, and therefore the project will not induce further population growth. The project will not result in the displacement of any homes or residents, nor will it result in a change in the location, distribution, density or growth rate of human population in the area. The project will not affect existing housing, or create a demand for additional houses nor will it, require the removal of any homes or the displacement of any people. _ I i I I Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact XIII PUBLIC SERVICES ! a. Would the project result in substantial adverse: ; physical impacts associated with the provision of new or physically altered governmental facilities, need for new or physically altered governmental { i facilities, the construction of which could cause" significant environmental impacts, in order to 3 maintain acceptable service ratios, response times or other performance objectives for any of the public services. 1. Fire Protection? " X 2. Police Protection? X j 3. Schools? X 4. Parks? X 5. Other Public facilities? X' Y- j SUMMARY Less Than Significant Impact. During construction, residents and emergency service vehicles will be able to access the construction site and all adjacent neighborhoods at all times Once the project is complete, the flood control maintenance project ;will not increase the need for fire or police protection, schools, parks or other governmental services. Periodic maintenance of the flood control Page 16 of 19 improvements will be performed by the County to ensure the facilities are operating in a safe and effective manner.. , Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact XIIII. RECREATION a. Would the project increase the use of existing neighborhood and regional parks or other recreational facilities such that substantial physical deterioration of the facility would occur or be accelerated? X b. Does the project include recreational facilities or require the construction or expansion of recreational facilities, which might have an adverse physical effect on the environment? X SUMMARY: Less than Significant Impact.,The excavation project is expected to have no effect on existing neighborhood parks in the area, but will temporarily affect the recreational use of the regional trail that uses the access road parallel to the Walnut Creek channel. This trail is maintained by East Bay Regional Parks, and portions of it will be closed temporarily during construction activities. Park authorities will be advised of the closure, and sections of the trail will be re-opened as soon as work in those areas is completed. Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact XV. TRANSPORTATION/TRAFFIC. Would the project: a. Cause an increase in traffic, which is substantial in relation to the existing traffic load and capacity of the street system (i.e., result in a substantial increase in either the number of vehicle trips, the volume to capacity ratio on roads, or congestion at intersections)? X b. Exceed, either individually or cumulatively, a level of service standard established by the county congestion management agency for designated roads or highways? X c. Result in a change in air traffic patterns, including either an increase in traffic levels or a change in location that results in substantial safety risks? X d. Substantially increase hazards due to a design feature (e.g., sharp curves or dangerous inter- sections) or incompatible uses (el.g., farm equipment)? X e. Result in inadequate emergency access? X f. Result in inadequate parking capacity? X g. Conflict with adopted policies, plans, or programs supporting alternative transportation (e.g., bus turnouts, bicycle racks)? X SUMMARY: Less Than Significant Impact. The majority of the project will take place in the flood control channels which are paralleled by access:roads, and not open to cars owned by the public. The areas adjacent I i Page 17 of 19 r to the flood control channels receive traffic from day use shoppers, due to the location of various box store and mini-mall locations here. Increase in traffic from construction workers will be negligible. Work at the project site is estimated to take approximately 30 - 40 days. Based on the relatively small number ! of truck trips generated (approximately 50 per day), and the limited number of days over which the trips will occur, the impact due to the transportation of fill to the nearby Tesoro Refinery is less than significant. Off haul of sediment in the dump trucks to the nearby Tesoro Refinery (Figure 2.), will lessen the distance needed to transport the material for disposal. i I Traffic on adjacent roadways may need to be temporarily stopped in order to allow dump trucks and other deliveries to enter and exit the access roads at the work site along various access points at the project site. However, •impacts to traffic will be temporary and minor. All 'attempts will be made to accommodate construction machinery entering and exiting the project area through County right-of-way onto minor roads. j I Portions of the recreational trail that parallels Walnut Creek will be closed during the de-silting project. The 4 East Bay Regional Parks District will be advised of the project, and will be advised of path closures. Pedestrians and bike riders using the recreational trail for alternative transportation will be temporarily affected by the project, however alternate street routes are available around the affected portion of the trail. Mitigation Traffic - 1: Traffic on adjacent roadways may need to be temporarily stopped in order to allow dump trucks and other deliveries to enter and exit the access roads at the work site along various access points at the project site. Flaggers will be used at complicated intersections when necessary to ensure traffic impacts remain at levels that are less then significant during the project. 1 i Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact i XVI. UTILITIES AND SERVICE SYSTEMS. 1 Would the project: j a. Exceed wastewater treatment requirements of the applicable Regional Water Quality Control Board? X b. Require or result in the construction of new water,or wastewater treatment facilities or expansion of existing facilities, the construction or which could cause significant environmental 1 effects? i X c. Require or result in the construction of new storm water drainage facilities or expansion of existing facilities, the construction of which could { cause significant environmental effects? 1 X d. Have sufficient water supplies available to serve i the project from existing entitlement and resources, or are new or expanded entitlement needed? X . e. Result in a determination by the wastewater . treatment provider, which serves or may serve the project that it has adequate capacity to serve the project's projected demand in addition to the provider's existing commitments? X f. Be served by a landfill with sufficient permitted capacity to accommodate the project's solid waste disposal needs? X g. Comply with federal, state and local statutes and regulations related to solid waste? X' I Page 18 of 19 i SUMMARY: No impact. The project will not require the addition of any wastewater treatment facilities or necessitate an increase in the use of public water. There are no solid waste issues associated with the project. Potentially Significant f Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact XVII. MANDATORY FINDINGS OF SIGNIFICANCE a. Does the project have the potential to degrade the quality of the environment, substantially reduce the habitat of a fish and wildlife species, cause a fish or wildlife population to drop below self-sustaining levels, threaten to eliminate a plant or animal community, reduce the number or restrict the range of a rare or endangered plant or animal or eliminate important examples of the major periods of California history or prehistory? X b. Does the project have impacts that are individually limited, but cumulatively considerable? ("Cumulatively considerable" means that the incremental effects of a project are considerable when viewed in connection with the effects of past projects, the effects of other current projects, and the effects of probable future projects)? X c. Does the project have environmental effects, which will cause substantial adverse effects on human beings, either directly or indirectly? X SUMMARY: Less than significant impact. The excavation project will temporarily impact wetlands in Lower Grayson Creek, but will return the flood plain to elevations more conducive to the formation of perennial wetlands. Seasonal wetlands in the Grayson Creek reach of the project are frequently inundated during winter flows. The low flow channel will be protected by 2 ft berms/buffers, separating them from construction activities. Vegetation in the excavated areas is expected to regenerate quickly following hydro-seeding, and the start of the rainy season. In Walnut Creek, areas of non-wetland (uplands) will be excavated to lower elevation to where re- establishment of perennial wetlands can occur; increasing wetland habitat in the channel. Emergent Marsh, and ponded areas in Lower Walnut Creek channel will remain intact habitat and will be protected from the excavation project with 2 foot berms/buffers. The project has been designed as self-mitigating. Wetlands avoided, and upland areas restored to perennial wetland elevations on Lower Walnut Creek mitigate for the impact to wetlands on Grayson Creek. j CDD: G:\GrpData\EngSvc\ENVIRO\Flood Control\LowerWC_GRAYDesilt\CEQA\CEQA_MitNegDecl.doc Page 19 of 19 j +i4 / Y co EAL y , IV to LO iyyr rr � Tc r rr! 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CP#05-30 Project # 7520 6139353.The project consists of floodplain restoration and de-silting excavation work in the floodplains of Lower Walnut Creek between Concord Blvd, and Drop Structure 1 (below Monument Blvd.), and Lower Grayson Creek from Highway 4 to Chipancingo Pkwy.).The low flow channel in both creeks will not be impacted during the excavation work, and will be protected by a two-foot berm/ buffer zone that will be flagged prior to start of construction. Identified non-wetland areas in Walnut Creek, and wetland areas in Lower Grayson Creek will be excavated to restore the flood plain to design elevations.To ensure that construction/excavation activities do not impact sensitive areas in the project area, temporary flagging with tape will be installed around wetland areas, the low flow channel, and ponded areas to delineate a two foot buffer zone/berm that will isolate sensitive areas from impacts during construction in Walnut Creek. Buffer zones will be established around the low flow channel of Lower Grayson Creek. County staff will instruct the contractor on installation of the buffer zone, and will be diligent with making sure that the buffer zone is strictly respected during construction. It will be necessary to construct approximately 8 - 10 temporary access ramps from the access road at the top of the flood control channel into the Lower Walnut Creek floodplain for machinery access during construction. These temporary ramps will be made of material excavated from the non-wetland areas of the floodplain, and will be removed after the project is complete. Each ramp will require approximately 125 cubic yards of material, and will extend from the top of the trapezoidal channel into the flood plain. Avoidance and minimization measures will be incorporated into the project to ensure that environmental impacts are kept to a less than significant level. The project was approved on Pursuant to the provisions of the California Environmental Quality Act: ❑ An Environmental Impact Report was prepared and certified (SCH# ) ❑ The Project was encompassed by an Environmental Impact Report previously prepared for (SCH # ). ® A Negative Declaration was prepared Copies of the record of project approval and the Negative Declaration or the final EIR may be examined at the office of the Contra Costa County Public Works Department. ® The Project will not have a significant environmental effect. ❑ The Project will have a significant environmental effect. ® Mitigation measures were made a condition of approval of the project. ❑ A statement of overriding considerations was adopted. ❑ Findings were adopted pursuant to Section 15091 of the State CEQA Guidelines. Date: By: Community Development Department Representative AFFIDAVIT OF FILING AND POSTING I declare that on I received and posted this notice as required by California Public Resources Code Section 21152(c). Said notice will remain posted for 30 days from the filing date. Signature Title Applicant: Department of Fish and Game Fees Due Public Works Department ❑ EIR-$850 Total Due: $$1,300 255 Glacier Drive ® Neg. Dec. -$1,250 Total Paid $ Martinez, CA 94553 ❑ DeMinimis Findings-$0 Attn: ® County Clerk-$50 Receipt#: CALIFORNIA ENVIRONMENTAL QUALITY ACT NOTICE OF DETERMINATION CONTRA COSTA COUNTY COMMUNITY DEVELOPMENT DEPARTMENT 651 PINE STREET 4TH FLOOR NORTH WING MARTINEZ, CALIFORNIA 94553-0095 Telephone: (925) 313-2296 Contact Person: Cece Sellgren, Environmental Planner Project Description, Common Name (if any) and Location: Lower Walnut Creek and Lower Grayson Creek Floodplain Restoration and De-Silting Project.CP# 05-30 Project #7520 6139353.The project consists of floodplain restoration and de-silting excavation work in the floodplains of Lower Walnut Creek between Concord. Blvd. and Drop Structure 1 (below Monument Blvd.), and Lower Grayson Creek from Highway 4 to Chipancingo Pkwy.). The low flow channel in both creeks will not be impacted during the excavation work, and will be protected by a two-foot berm/ buffer zone that will be flagged prior to start of construction. Identified non-wetland areas in Walnut Creek, and wetland areas in Lower Grayson Creek will be excavated to restore the flood plain to design elevations. To ensure that construction/excavation activities do not impact sensitive areas in the project area, temporary flagging with tape will be installed around wetland areas, the low flow channel, and ponded areas to delineate a two foot buffer zonelberm that will isolate sensitive areas from impacts during construction in Walnut Creek. Buffer zones will be established around the low flow channel of Lower Grayson Creek. County staff will instruct the contractor on installation of the buffer zone, and will be diligent with making sure that the buffer zone is strictly respected during construction. It will be necessary to construct approximately 8 -10 temporary access ramps from the access road at the top of the flood control channel into the Lower Walnut Creek floodplain for machinery access during construction. These temporary ramps will be made of material excavated from the non-wetland areas of the floodplain, and will be removed after the project is complete. Each ramp will require approximately 125 cubic yards of material, and will extend from the top of the trapezoidal channel into the flood plain. Avoidance and minimization measures will be incorporated into the project to ensure that . environmental impacts are kept to a less than significant level. The project was approved on Pursuant to the provisions of the California Environmental Quality Act: ❑ An Environmental Impact Report was prepared and certified (SCH # ) ❑ The Project was encompassed by an Environmental Impact Report previously prepared for (SCH# ). ® A Negative Declaration was prepared Copies of the record of project approval and the Negative Declaration or the final EIR may be examined at the office of the Contra Costa County Public Works Department. ® The Project will not have a significant environmental effect. ❑ The Project will have a significant environmental effect. ® Mitigation measures were made a condition of approval of the project. ❑ A statement of overriding considerations was adopted. ❑ Findings were adopted pursuant to Section 15091 of the State CEQA Guidelines, Date: By: Community Development Department Representative AFFIDAVIT OF FILING AND POSTING I declare that on I received and posted this notice as required by California Public Resources Code Section 21152(c). Said notice will remain posted for 30 days from the filing date. Signature Title Applicant: Department of Fish and Game Fees Due Public Works Department ❑ EIR-$850 Total Due: $ $1,300 255 Glacier Drive ® Neg. Dec.-$1,250 Total Paid $ Martinez, CA 94553 ❑ DeMihimis Findings- $0 Attn: ® County Clerk-$50 Receipt#: Community "",AICD Development SNS I D Er, 0 i�' ` Development Director Department - r- County Administration Building IJ 651 Pine Street 5 I^ 4th Floor, North Wing f , Martinez, California 94553-0095 .!s I MAR 2 j 2006 2 ,. w.iliaM46F-E: Phone: ' - OST'4 COVH� S.L. 1^lF'IR, COUNTY CLERK ON A ST COUNTY March 16, 2006 BYE DEPUTY NOTICE OF PUBLIC REVIEW AND INTENT TO ADOPT A PROPOSED MITIGATED NEGATIVE DECLARATION County File # CP 05-30 Pursuant to the State of California Public Resources Code and the "Guidelines for Implementation of the California Environmental Quality Act of 1970" as amended to date, this is to advise you that the Community Development Department of Contra Costa County has prepared an initial study on the following project: Lower Walnut Creek and Lower Grayson Creek Floodplain Restoration and De- Silting Project, CP#: 05-30 The project consists of floodplain restoration and de-silting excavation work in the floodplains of Lower Walnut Creek between Concord Blvd. and Drop Structure 1 (below Monument Blvd.), and Lower Grayson Creek from Highway 4 to Chipancingo Pkwy.). The low flow channel in both creeks will not be impacted during the excavation work, and will be protected by a two-foot berm/ buffer zone that will be flagged prior to start of construction. Identified non-wetland areas in Walnut Creek, and wetland areas in Lower Grayson Creek will be excavated to restore the flood plain to design elevations. Removal of silt from the floodplains of both Lower Walnut Creek channel and Lower Grayson Creek Channel will be conducted with the use of excavators, and /or front end loaders working in the floodplain loading dump trucks. The excavators will only be present in the non-wetland areas of the Lower Walnut Creek channel, but will be in the flood plain area of the Lower Grayson Creek Channel containing seasonal wetlands. The excavators and dump trucks will access the site from adjacent access roads (located at the top of the trapezoidal channel) and by temporary access ramps created throughout the project site into the floodplain. In the narrow reach between 2nd Ave. S and Chilpancingo Pkwy. a long-reach excavator may be used from the top of bank to remove silt deposits identified here. Other construction equipment (e.g. general use pickup trucks, etc.) will be used as necessary. A number of avoidance and minimization measures have been included in the project to avoid impact to special status species including: 1) establishing a two-ft. buffer (berm) around the perimeter of the stream channel in both channels, and around ponds and selected wetlands in Walnut Creek during the project construction, 2) equipment will be properly maintained to ensure deleterious fluids are not allowed to enter the creek (or floodplain area), 3) work will be conducted during the dry season of any given year and 4) all work will avoid the low flow channels of both creeks. Public Comment Period — The period for accepting comments on the adequacy of the environmental document extends to April 21 , 2006. Office Hours Mondayp- Fri a £-�-00 a.m. - 5:00 p.m. Office is closed the 1st, 3ai th Fridays of each month a 1 ANY COMMENTS SHOULD BE IN WRITING AND SUBMITTED TO THE FOLLOWING ADDRESS: Carrie Dovzak, Planner II Contra Costa County Public Works Department 255 Glacier Drive Martinez, CA 94553 The environmental document is expected to go before the County Board of Supervisors on or around May 2, 2006, To confirm the Board date, please;contact;GarrleDovzakat (925) 3=13"21••9.0: Any questions regarding the project itself, should be directed to: Paul Detjens, (925) 313-2394 Contra Costa County Public Works Department 255 Glacier Drive Martinez, CA 94553 G:\GrpData\EngSvc\ENVIRO\Long Term Prois\Public—wks—expansion\CEQA\Notice of Public Review Letter.doc Cc: County Clerk's Office Public Works— P.Detjens, FC C.Dovzak-Enviro t • i I I i Page 2'of 2 CONTRA PUBLIC WORKS DEPARTMENT COSTA INITIAL STUDY COUNTY OF ENVIRONMENTAL SIGNIFICANCE PROJECT WO# 9353 CP# 05-30 PROJECT NAME: Lower Walnut Creek and Lower Grayson Creek Floodplain Restoration and De-silting Project PREPARED BY: Carrie Dovzakx/ DATE: February 9, 2006 APPROVED BY: !='/ DATE: RECOMMENDATIONS: ( ) Categorical Exemption (Class ) () Negative Declaration ( ) Environment Impact Report Required (X) Mitigated Negative Declaration The project will not have a significant effect on the environment. The recommendation is based on the following: There is no substantial evidence that the project or any of its aspects may cause a significant effect on the environment (Sec. 15063(b)(2)). What changes to the project would mitigate the identified impacts. N/A USGS Quad Sheet Walnut Creek Base Map Sheet# G-13, 14; H-13,14; J-13,14 Parcel # n/a GENERAL'CONSIDERATIONS: 1. Location: This de-silting and floodplain restoration project is located along the lower reaches of two flood control channels - Walnut Creek and Grayson Creek, in north-central Contra Costa County. The project limits are: Walnut Creek - from approximately Concord Blvd. to Drop Structure 1 (1/2 mile upstream of Willow Pass Road), and Grayson Creek from 1-680 to Chipancingo Pwy. (Figures 1, 2). 2. Project Description: Lower Walnut Creek and Lower Grayson Creek Floodplain Restoration and De-silting Project consists of sediment removal in the lower reaches of the Lower Walnut Creek and Lower Grayson Creek flood control channels, to restore the appropriate level of flood protection, and to restore the elevation of the floodplain to a more appropriate level for the stream channel to utilize it during high flow. The project will involve excavation almost exclusively with only minor amounts of temporary fill to facilitate access to the channel flood plain bench. G:\GrpData\EngSvc\ENVIRO\Flood Control\LowerWC_GRAYDesilt\CEQA\Initial Study Cover.doc Page 1 of 2 This Initial Study addresses potential environmental impacts associated with operation of the project. 3. Does it appear that any feature of the project will generate significant public concern? [ ] yes [✓ ] no [ ] maybe (Nature of concern): 4. Will the project require approval or permits by other than a County agency? [X] yes [ ] no SF Region Regional Water Quality Control Board, U.S. Army Corps of Engineers, CA Dept. of Fish and Game 5. Is the project within the Sphere of Influence of any city? Yes, City of Pleasant Hill and City of Concord. G:\GrpData\EngSvc\ENVIRO\Flood,Controi\LowerWC_GRAYDesilt\CEQA\Initial Study Cover.doc Page 2 of 2 Environmental Checklist Form 1. Project Title: Lower Walnut Creek and Lower Grayson Creek Floodplain Restoration and De-Siltinq Project 2. Lead Agency Name and Address: Contra Costa County Community Development Department 651 Pine Street, North Wing - 4th Floor Martinez, CA 94553 3. Contact Person and Phone Number: Carrie Dovzak, Planner If (925) 313-2190 Contra Costa County Public Works Department 255 Glacier Drive Martinez, CA 94553 4. Project Location: The project is located in unincorporated Contra Costa County, the City of Concord, and the City of Pleasant Hill. Lower Walnut Creek and Lower Grayson Creek. (Figures 1 and 2.) 5. Project Sponsor's Name and Address: Contra Costa County Public Works Dept. 255 Glacier Drive Martinez, CA 94553 6. General Plan Designation: Multiple: Open Space, PS 7. Zoning: Public/Semi-public 8. Description of Project: The project consists of floodplain restoration and de-silting excavation work in the floodplains of Lower Walnut Creek between Concord Blvd. and Drop Structure 1 (below Monument Blvd.), and Lower Grayson Creek from Highway 4 to Chipancingo Pkwy.). The low flow channel in both creeks will not be impacted during the excavation work, and will be protected by a two-foot berm/ buffer zone that will be flagged prior to start of construction. Identified non-wetland areas in Walnut Creek, and wetland areas in Lower Grayson Creek will be excavated to restore the flood plain to design elevations. Lower Walnut Creek and Lower Grayson Creek were engineered from narrow creek corridors into trapezoidal channels in the early 1960's to provide flood control for the cities and property owners along its corridor, and to expedite flood waters from the upper watershed to the Sacramento River. Several reaches were de-silted in 1993, 1995 and 1997, and have, since then, exceeded their capacity for flood control from silt deposits on their flood plains. The desilting planned will restore the flood control capacity of the channels. A CCC Flood Control and Water Conservation District (District) right of way, including District access roads, exist on both sides of the channels. The project lies within unincorporated Contra Costa County, The City of Pleasant Hill, and the City of Concord. Real Property transactions may be necessary in support of this project. 9. Surrounding Land Uses and Setting: Lower Walnut Creek and Lower Grayson Creek flow through a variety of land use, but the predominant land uses along the corridors are commercial and industrial. The commercial properties range from shopping centers and box stores, to landfills, and an airport. While the largest percentage of land use is the airport, mixed commercial and industrial uses are also prevalent. A small percentage of the land use is single family residential housing. See Figure 2. 10. Other public agencies whose approval U. S.Army Corps of Engineers, SF District of the Regional (e.g., permits, financing approval, or water Quality Control Board,California Department of Fish and Game participation agreement). Page 1 of 19 j i i ENVIRONMENTAL FACTORS POTENTIALLY AFFECTED: j s I The environmental factors-checked below would be potentially affected by this project, involving at least ones impact that is a "Potentially Significant Impact" as indicated by the i checklist on the following pages. Land Use&Planning X Transportation/Circulation Public Services Population& Housing X Biological Resources I Utilities &Service System's Geological Problems Energy& Mineral Resources Aesthetics X Water X Hazards Cultural Resources Air Quality Noise j Recreation Mandatory Findings of No Significant Impacts Significance Identified DETERMINATION' On the basis of this initial evaluation: i I find that the proposed project COULD NOT have a significant effect on the environment, and a NEGATIVE DECLARATION will be prepared. ; • i I find that although the proposed project could have a significant effect on the environment, there will not be a significant effect in this case because the mitigation measures described on an attached sheet have been X added to the project. A MITIGATED NEGATIVE DECLARATION will be prepared. i I find that the proposed project MAY have a significant effect on the environment, and an ENVIRONMENTAL IMPACT REPORT is required. I find that the proposed project MAY have a significant effect(s) on the environment, but at least one effect (1) has been adequately analyzed in an earlier document pursuant to applicable legal standards, and (2) has been .addressed by mitigation measures based on the earlier analysis as described on attached sheets, if the effect is a "potentially significant impact' or "potentially significant unless mitigated.". An ENVIRONMENTAL IMPACT REPORT is required, but it must analyze only the effects that remain to be addressed. I find that although the proposed project could have a significant effect on the environment, there WILL NOT be a significant effect in this case because all potentially significant effects (a) have been analyzed adequately in an earlier EIR pursuant to applicable standards and (b) have been avoided or mitigated pursuant to that earlier EIR, including revisions or mitigation measures that are imposed upon the proposed project. . j . Signature Date Contra Costa County Community Development Department Print Name I i i i } i Page 2 of 19 SOURCES In the process of preparing the Checklist and conducting the evaluation, the following references (which are available for review at the Contra Costa County Community Development Department, 651 Pine Street 5th Floor-North Wing, Martinez) were consulted: 1. Contra Costa Resource Mapping System - Quad Sheet Panels—Vine Hill—Walnut Creek 2. The (Reconsolidated) County General Plan (July 1996) and EIR on the General Plan (January 1991) 3. Contra Costa County Important Farmland Map 2002, California Department of. Conservation Division of Land Resources Protection 4. Field reviews by Public Works staff, Biosearch, Entrix, Natural Resouces Management, Jones and Stokes, ACOE and/or Project Description (including coordination with Design Engineer) 5. Data Summary Report for the Baseline Surveys of Anadromous Fish Habitat in Lower Walnut Creek, Contra Costa County, CA (with 11 X 17 maps) Jones and Stokes, 2004. 6. Data Collection Plan for Baseline Surveys of Anadromous Fish Habitat, and Draft Delineation of Waters of the United States, Including Wetlands, for the Lower Walnut Creek Channel Restoration Project, Concord, California —January 2005 (with 11 X 17 maps) Jones and Stokes, 2004. 7. Wildlife Habitat Assessment for the Lower Walnut Creek Channel Restoration Project — December 2004 (NRM, January 2005). 8. Botanical Report for the Lower Walnut Creek Channel Restoration Project (with 11 X 17 maps) (Jones and Stokes, January 2005). Y 9. Delineation of Waters of the United States, Including Wetlands for the Lower Walnut Creek Channel Restoration Project Report. ACOE File number 29296S (NRM/Jones and Stokes, July 2004). 10. Contra Costa County Soils Report,Soil Conservation Service, 1977. 11. Grayson Creek Habitat Assessment—August 2005. Entrix, Inc. Walnut Creek, CA. 12. Lower Grayson Creek Project Wetland Delineation —August 2005. ACOE File number 29898S. (Preliminary jurisdictional determination) Entrix, Inc. Walnut Creek, CA. 13. ABAG Earthquake Liquefaction Maps 2001. http://www.abag.ca.govlbayarea/eamaps/ 14. Towill, Inc. (2004) Topographic data and digital orthophotography of Lower Walnut Creek and Lower Grayson Creek. 15. National Marine Fisheries Service —Central Valley Chinook Salmon Essential Fish Habitat— Fall Run. http://swr.nmfs.noa6.ciov/fall.htm 16. Map: Survey Results of post-12/31/05 storm. Water surface elevation in channels. Page 3 of 19 i •I EVALUATION OF ENVIRONMENTAL IMPACTS: Potentially Significant Potentially Unless Less than Significant Mitigation 'Significant Impact Incorporation Impact No Impact I L AESTHETICS. Would the proposal; a. Have a substantial adverse effect on a scenic vista? X' b. Substantially damage scenic resources, including, but not limited to, trees,rock, outcroppings, and historic buildings within a state scenic highway? X c. Substantially degrade the existing visual character or quality of the site and•its surroundings: ( X d. Create a new source of substantial light or glare, which would adversely affect day or nighttime views in the area? ; X SUMMARY: Less than Significant Lower Walnut Creek and Lower Grayson Creek channels were designed to provide flood protection for low lying ,areas adjacent to and surrounding the channels in the early 1960's. The trapezoidal channels were designed void of riparian cover and vegetation to expedite flood waters through the channel to'the Sacramento River. Routine maintenance of the channels keeps the channels clear of mature vegetation. I Construction activities will be visible to residents living adjacent to Lower Grayson Creek channel in areas adjacent to Buchanan Airport, and south of Pacheco Blvd.; however, construction is temporary and is not expected to cause significant aesthetic impacts. The majority of the landuse in the project area is industrial and commercial. All disturbed areas will be hydro-seeded with ia .seed mix that includes native grasses. Construction activities are not expected to occur at night, therefore, supplemental lights will not be necessary. Following construction, the project site is expected to return to pre-project vegetated condition. I Potentially Significant Potentially Unless Less than Significant Mitigation ' Significant Impact ! Incorporation Impact No Impact II. AGRICULTURAL RESOURCES. In determining whether impacts to agricultural resources are significant environmental effects, lead agencies may refer to the California Agricultural Land Evaluation and Site Assessment Model (1997) j prepared by the California Dept. of Conservation as an optional model to use in assessing impacts on agricultural and farmland. Would the project: a. Convert Prime Farmland, Unique Farmland, or I Farmland of Statewide, Importance (Farmland), as shown on the maps prepared pursuant to the Farmland Mapping and Monitoring Program of the California Resources Agency, to non- agricultural use? X b. Conflict with existing zoning for agricultural use, or a Williamson Act contract? X c. Involve other changes in the existing X Page 4 of 19 i i Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact environment, which, due to their location or nature, could result in conversion of Farmland, to non-agricultural use? SUMMARY: No Impact. The project will not affect any locally or statewide important farmland. The land immediately adjacent to the project consists of roadways, commercial properties, and industry. The Contra Costa County Important Farmland Map (FMMP, 2002) identifies the majority of the project as being within an area designated as "urban and built up land. The proposed project area is not currently used for agricultural purposes. Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact III. AIR QUALITY. Where available, the significance criteria established by the applicable air quality management or air pollution control district may be relied upon to make the following determinations. Would the project: a. Conflict with or obstruct implementation of the applicable air quality plan? X b. Violate any air quality standard or contribute to an existing or projected air quality violation? X c. Result in a cumulatively considerable net increase of any criteria pollutant for which the project region is non-attainment under an applicable federal or state ambient air quality standard (including releasing emissions which exceed quantitative thresholds for ozone precursors)? X d. Expose sensitive receptors to substantial pollutant concentrations? X e. Create objectionable odors affecting a substantial number of people? X SUMMARY: Less Than Significant Impact. Short-term emissions and objectionable odors may be generated during construction; however, they will be minor and temporary. To minimize impacts due to construction activities, contract specifications will stipulate the use of properly tuned and muffled equipment and the elimination of unnecessary idling of equipment when not in use. Implementation of dust control practices including general watering of exposed areas will be utilized to minimize air quality impacts. The minor temporary deterioration of ambient air quality during construction will end once construction is completed; therefore, there will be no.potentially adverse long-term impacts to air quality. Page 5 of 19 } i I 1 Potentially t Significant Potentially Unless Less than I' Significant Mitigation Significant Impact Incorporation Impact No Impact IV. BIOLOGICAL RESOURCES. Would the project: a. Have a substantial adverse effect, either directly or through habitat modifications, on any species identified as a candidate, sensitive, or 4 special status species in local or regional plans, polices, or regulations, or by the California Department of Fish and Game or U.S. Fish and I "Wildlife Service? X b. Have a substantial adverse effect on any i riparian habitat or other sensitive natural community identified in local or regional plans, policies, regulations or by the California f Department of Fish and Game or US Fish and Wildlife Service? X c. Have a substantial adverse effect on federally protected wetlands as defined by Section 404 of the Clean Water Act (including, but not limited to, marsh, vernal pool, coastal, etc.) through direct removal, filling, hydrological interruption, or other means? X d. Interfere substantially with the movement of any native resident or migratory fish or wildlife species or with-established native resident or migratory wildlife corridors, or impede the use of native wildlife nursery sites? X e. Conflict with any local policies or ordinances protecting biological resources, such as tree preservation policy or ordinance? , X f. Conflict with the provisions of an adopted Habitat Conservation Plan, Natural Community Conservation Plan, or other approveddocal, regional, or state habitat conservation plan? X SUMMARY: Potentially Significant Unless Mitigation Incorporated. Various studies in support of biological resources in the project area were carried out from 2003 — 2006 which identified listed species and habitats within or adjacent to the project area that need special consideration. A Habitat Assessment of the Lower Walnut Creek project site was conducted by Natural Resources Management (Berkeley,CA), in May 2004 to characterize the habitats present here and the likelihood of special status species occurring in the area. Similarly, a biological assessment was completed by Jones and Stokes (January, 2005). A Section 404 Clean Water Act Jurisdictional Delineation was conducted by Jones and JStokes in May 2004 and confirmed by the United States Army Corps of Engineers (USACOE) on January 21, 2005 (Corps File No. 29296S). Similar wetland and habitat studies were carried out on Lower Grayson iCreek by Entrix, Inc. in August 2005. A Section 404 Clean Water Act Jurisdictional Determination was confirmed on the Lower Grayson Creek (Corps File No. 29898S) area on January 3, 2006. A wetland delineation of Lower Grayson Creek between Pacheco Blvd. and Chilpancingo Pkwy. is currently in progress. Activities associated with the project will occur within California Department of Fish and Game, Regional Water Quality Control Board, and U.S. Army Corps of Engineer's jurisdiction. Permits for the project will be obtained from these agencies. Page 6 of 19 Based on the limited habitat in the channels, and the proximity to the surrounding urban area, impact to listed species as a result of the project is unexpected. Consultants for the project have identified species that may have potential of occurrence in the project area: California red-legged frog (Rana aurora draytonil), Western pond turtle (Clemmys marmorata), Central Valley Fall run Chinook salmon and various species of birds and special status bats. Special Status Wildlife and Species of Concern California Red legged frog Based on observations by wildlife consultants working on the habitat assessments, there is a low potential for RLF habitat in the project area due to the urbanization of the area, and the presence of,various predatory species identified in the creek surveys. In addition, since riparian habitat is lacking, there is limited cover for red-legged frog. Review of the CNDDB indicates the closest known sitings of RLF is approximately 5 miles away in the Martinez Hills (west), and 5 miles east in the foothills of the Mt. Diablo Watershed. These habitats are not connected to the Walnut Creek/Grayson Creek watersheds and are separated from the project site by extensive urban and industrial landuse. Large numbers of predatory species (including mosquito fish, crayfish and bullfrogs) have been identified in portions of Walnut and Grayson Creeks as well. For these reasons RLF are not expected to be impacted by the project. Western Pond Turtle The Western Pond Turtle is a federal and state species of concern, and is a California Fully Protected species. No occurrences of western pond turtle were observed during the habitat survey, nor are observed within 5 miles of the project site according to the CNDDB database. However, suitable habitat for.the species may occur at the project site along Grayson Creek, where cattails provide cover near side channels. If any western pond turtles are found during construction, they will be relocated to an area not subject to disturbance. Mitigation Bio - 1: if any western pond turtles are found during construction, they will be relocated to an area not subject to disturbance. Birds Since the project site covers a large area, there is potential for birds to forage or nest in the site during various times of the year. Special Status birds identified as having the potential to be in the general area include California black rail, Suisun Song Sparrow, Salt Marsh Yellow.Throat, White-tailed Kite and Loggerhead Shrike. Birds that prefer the Salt Marsh environment (Clapper Rail, Suisun song sparrow and Salt Marsh Yellow Throat) would prefer the northern tidally influenced portion of Lower Walnut.Creek, where there are large expanses of pickleweed and tidally effected marsh land. This area is not in the project area, and no tidal marsh habitat will be impacted by the project. Landuse in the project area is predominantly urban. The channels are bordered by shopping malls, hotel complexes and dense commercial real estate. To avoid impact to nesting birds in ,the project area, avoidance and minimization measures will' be implemented including, timing construction during the late summer, and at the end of the breeding window for these special status birds. Mitigation Bio'- '2: Construction will avoid breeding season for nesting birds. Construction activities will occur in late summer in order to ensure that impacts to sensitive bird species are minimized. Nesting raptors Tall trees adjacent to the access roads above theLower Walnut Creek Channel may be the site of nesting raptors. Avoidance and minimization measures used for nesting birds will be extended to raptor nests found near'the project site. There are no mature trees in the project area that will be affected by the de-silt operation. Most mature trees near the project area'are part of landscaping for nearby malls, and parking areas which are heavily impacted by human and automobile traffic. Page 7 of 19 i I° Mitigation-Bio - 3: Same as Mitigation Bio -2: Special-status Bat.Species I . Several species of bats that are Federal Species of Concern; may roost in bridges and nearby buildings adjacent to both Lower Grayson Creek and Lower Walnut Creek. There are four road overpasses in the project area. Suitable foraging habitat occurs adjacent to both creeks, but it will not be affected by construction. Project`construction will occur outside of the breeding times for bat species. If special status bat species are identified during construction, the District will work with the bat specialist, as well as the California Department- of Fish and Game, to ensure the species-are adequately protected.' Currently there are no special-status bat species listings in-the CNDDB in the project vicinity. Fall run Chinook-Salmon Since both creek corridors have been identified as possible migration.routes and spawning sites for Chinook salmon, studies were carried out to identify stream characteristics in relation to spawning and rearing habitat for this protected species (Jones and Stokes, 2004, 2005. Entrix, 2005). I Central Valley Fall Chinook have been observed migrating up the Walnut Creek Channel from'the Sacramento River in late Fall. The District has co-sponsored several ongoing'studies with ACOE (Sacramento) to assess habitat quality, and spawning success (viability of redds and eggs) in the Walnut Creek channel from the Sacramento River to the first major migration barrier (Drop #1). Although the Walnut Creek channel continues to support migration'and spawning of adult Chinook salmon, the diversity and complexity of channel habitat in Lower Walnut Creek is low. The de-silting project will occur before the Fall migration up Walnut Creek channel begins, therefore there will be no salmon present during the time period of the project. The project work will occur in the dry season and avoid the stream channel. Avoidance and minimization measures to avoid impact to the stream channel, and re-establish vegetation in the flood plain after the desilt, will be implemented. These include 1) establishing a two-ft. buffer (berm) around the perimeter of the stream channel, ponds and selected wetlands during the project construction 2) construction will occur before the 'migr'ation window for Fall Chinook occurs 3) equipment will be properly maintained to ensure deleterious fluids are not allowed to enter the creek (or floodplain area), 4) work will be conducted during the dry season of-any given year. For these reasons, no impacts to salmonids are expected as a result of the project. MiAgation Bio - 4: Construction will avoid the low flow channel completely in the Lower Grayson`Creek and Lower Walnut Creek channels. Mitigation Bio — 5: Construction will not occur during the migration window for Fall run Chinook salmon; construction will occur during the dry season. Mitigation Bio — 6: A two-ft 'berm/barrier will be left between sensitive wetland areas in Lower Walnut Creek and construction areas. This berm will delineate the construction areas from sensitivehabitat, and will prevent impact to identified habitat. Wetlands An ACOE confirmed wetland delineation has been completed for the Lower Walnut Creek project area (Corps File No. 29296S), and the Lower Grayson Creek (Corps File No.298980S) project area. A wetland delineation of Lower Grayson Creek between Pacheco Blvd. and Chipancingq Pkwy. is currently in progress. Areas of seasonal wetlands and emergent.marsh, as well as `Other Waters of.the U.S. ` (the low flow channel and ponds) were delineated in the project'area under ACOE jurisdiction. Large areas of non-wetland, were also delineated. 1 Page 8 of 19' I i A considerable amount of silt has been deposited in the Lower Walnut Creek channel since the last de-silting operation in 1997, and areas of upland within the corridor have increased. These areas were identified in the ACOE wetland confirmation as 'non-wetland' (Jones and Stokes, 2005), and will be removed as part of the project to restore flood capacity within the channel. Non—wetland areas are dominated by ruderal species such as ripgut brome, black mustard, Italian thistle, Bermuda grass and slender wild oats. Identified wetland areas within the Lower Walnut Creek channel will be protected during the de-silting operation, as will the low flow stream channel and ponds. This will leave valuable habitat intact. A two-ft buffer zone around wetland areas will ensure that sensitive areas are isolated from construction activities. Similar wetland conditions exist in the Lower Grayson corridor between 1-680 and Pacheco Blvd., and these wetlands are also within US Army Corps of Engineer's jurisdiction. Since the channel is narrower here than in Walnut Creek, and the floodplain does not exhibit upland areas of non-wetland, excavation will involve desilting within the seasonal wetlands to return the channel to design capacity. This impact will be temporary as the excavated areas of wetland here will be returned to elevations conducive to the re-establishment of perennial wetlands. The project has been specifically designed to be self-mitigating: temporary impacts to wetlands,within Grayson Creek due to the desilting will be compensated for in two ways: 1) avoidance of existing wetlands on Walnut Creek and 2) reestablishment of wetlands on both Walnut Creek and Grayson Creek. 1) Avoidance of existing wetlands' Desilting activities within Lower Walnut Creek have been designed to avoid impacts to existing wetlands. Temporary flagging with tape will be installed around wetland areas, the low.flow channel, and ponded areas to delineate a two foot buffer zone/berm to isolate sensitive areas from impacts during construction. No wetland areas will be impacted by the desilting activities on Walnut Creek with the exception of 0.1 acre of temporary impact due to access road installation. 2) Reestablishment of wetlands Approximately 7 acres of non-wetland areas in the Lower Walnut Creek channel will be lowered to an elevation appropriate for the stream channel that is expected to support the re-establishment of perennial wetlands. Wetland areas in the Lower Grayson Creek channel will be desilted to a similar elevation, also ultimately converting the entire area into perennial wetlands. These mitigation measures will be implemented in coordination with the Army Corps of Engineers and San Francisco Bay Regional Water Quality Control Board (see attached Appendix A: Mitigation Monitoring Plan). County staff will coordinate with staff from the resource agencies regarding the project, and the appropriate agreements and permits will be obtained prior to implementation of the project. The County will comply with all conditions negotiated during the permit acquisition process. County staff is currently applying for coverage under Corps' Nationwide permit program under Section 404 of the.Clean Water Act. Mitigation Bio— 7: See Mitigation Bio—6 above. Mitigation Bio — 8: The project is designed to be self mitigating. Exisiting wetland areas in Walnut Creek will be specifically avoided by the project and areas of non-wetland in the Walnut Creek channel will be lowered to an elevation more conducive to re-establishment of perennial wetlands, compensating for the temporary impact to wetlands in Lower Grayson Creek. Wetlands impacted within Lower Grayson Creek are expected to recover rapidly as evidenced by past de-silting projects in this creek. Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact V. CULTURAL RESOURCES. Would the project: a. Cause a substantial adverse change in the X Page 9 of 19 r 1 (. Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact . Incorporation Impact No Impact significance of a historical resource as defined in §15064.5? b. Cause a substantial adverse change in the significance of an archaeological resource i pursuant to §15064.5? X c. Directly or indirectly destroy a unique paleontological resource or site or unique.. geologic feature? { , X d. Disturb any human remains, including those interred outside of formal cemeteries?. i X SUMMARY:. Less Than Significant Impact. - The channels were originally excavated in the early 1960's, and most recently desilted in 1993, 1995 and 1997. Project specifications for the de-silting work will not allow excavation below the design level for the channel; therefore all areas that will be disturbed by the project have been previously impacted, and new findings,of in-situ archaeological importance are not anticipated. Standard construction contract specifications for the project will include measures'related to discovery of cultural resources, including`informing personnel connected with the project of the possibility of finding archaeological and/or historical resources, requiring notification 'of the Resident Engineer in the event of a discovery, and retention of a cultural resources consultant to provide assistance in the event of a discovery. In addition, the Resident Engineer for the project will receive instruction regarding identification of archaeological and historical resources in the field. In particular, the specifications will require work to be halted in the event of an archaeological discovery within 85 feet of the discovery. An archaeological consultant shall be contacted and he/she shall inspect the site before advising the resident engineer to authorize further work. i Potentially 'Significant Potentially Unless Less than Significant Mitigation Significant ImpactIncorporationImpact No Impact VI. 'Geology and Soils. Would the project: a. Expose people or structures to potential substantial adverse effects, including the risk of loss, injury, or death involving: ! 1. Rupture of a known earthquake fault, as delineated on the most recent Alquist-Priolo Earthquake Fault Zoning Map issued by the State Geologist for the area or based on other substantial evidence of a known fault? Refer to Division of Mines and Geology,Special Publication 42. X 2. Strong seismic ground'shaking? X 3. Seismic-related ground failure, including liquefaction? X 4. Landslides? X b. Result in substantial soil erosion or the loss of i topsoil? X c. Be located on a geologic unit or soil that is unstable, or that would become unstable as a - result of the project, and potentially result in on- or off-site landslide, Iat&al spreading, subsidence, liquefaction or collapse? X d. Be located on expansive soil, as defined in Table 18-1-B of the Uniform Building Code X i Page 10 of 19 i l I E Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact (1994), creating substantial risks to life or property? e. Have soils incapable of adequately supporting the use of septic tanks or alternative waste disposal systems where sewers are not available for the disposal of wastewater? X SUMMARY Less Than Significant Impact. Exposure of people or property to geologic hazards is not expected to increase as a result of the project. Grading and excavation associated with the channel maintenance will result in a minor change in topography in the channel, and temporarily increase the exposure of soils'to wind erosion. -However, this is a less than significant and temporary impact. Adherence to standard dust control and erosion control practices, including, but not limited to, general watering of exposed areas will minimize impacts. Contract specifications will require flagging a two foot berm/buffer zone between the limits of excavation and identified sensitive wetlands and other waters of the U.S.' to prevent soil from these areas during construction activities. These measures will be incorporated into the construction contract. De-silting of the project area will not result1n unstable earth conditions or change geologic substructures. Exposure of people or property to geologic hazards is not expected to occur as a result of the project. In order to stabilize exposed soils, all areas left exposed due to the de-silting work will be hydra-seeded with a mix that includes native grasses, at the earliest practicable date. Hydro-seeding will stabilize the exposed sediment in the floodplain until vegetation is naturally established. Vegetation in the floodplain is expected to establish quickly, as it has in past de-silting operations. Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact VII. HAZARDS AND HAZARDOUS MATERIALS. Would the project: a. Create a significant hazard to the public or the environment through the routine transport, use, or disposal of hazardous materials? X b. Create a significant hazard to the public or the environment through reasonably foreseeable upset and accident conditions involving the release of hazardous materials into the environment? ' X c. Emit hazardous emissions or handle hazardous or acutely hazardous materials, substances, or waste within one-quarter mile of an existing or proposed school? X d. Be located on a site which is included on a list of hazardous materials sites compiled pursuant to Government Code Section 65862.5 and, as a result, would it create a significant hazard to the public or the environment? I X e. For a project located within an airport land use plan or, where such a plan has not been adopted, within two miles of a public airport or X Page 11 of 19 . =;f Potentially r Significant Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact public use airport, would the project result in a safety hazard for people residing or working in the project area. ; f. For a project within the vicinity of a private t airstrip, would the project result in a safety hazard for people residing or working in the project area? X g. Impair implementation of or physically interferes with an adopted emergency response plan or emergency evacuation plan? X h., Expose people or structures to a significant risk ; t: of loss, injury or..death involving wildland fires, including where wildlands are adjacent.to urbanized areas or where residences are intermixed with wildlands? X SUMMARY: Potentially Significant Unless Mitigation Incorporated. Sediments deposited on the floodplain of Lower Walnut Creek, and Lower Grayson Creek may have the potential to contain hazardous materials (such as concentrations of metals or hydrocarbons) that could pose a threat to the surrounding environment if not handled-, or disposed of properly. The District will create a soil sampling.plan that will represent various points throughout the project area where the floodplain will be de-silted. The current plan for the excavated material entails transporting it to the nearby Tesoro Refinery and stockpiling the sediment in an upland location (Figure 2.). Soil samples will be analyzed at a certified laboratory for various constituents identified by Tesoro Refinery before they will accept the soil for disposal. If Tesoro Refinery cannot accept the soil,.it will be properly managed and disposed of at a licensed facility. i The project has the potential to release hazardous substances, such as accidental petroleum spills from equipment, during construction. Per the contract specifications, standard construction safety practices will be followed during construction to ensure no accidental release of hazardous substances occurs and no increase in the potential for exposure to these substances occurs. There are 4 road crossings above the channel that may contain utility lines. Project designs will identify these utility and road crossings so that their locations can be clearly marked in the field, and avoided by construction activities. No interference with an emergency evacuation or response is expected to result from the project. Traffic control measures near the work area will minimize the potential for;accidents.. Maintenance roads parallel the project site at both creeks, enabling maintenance vehicles to avoid`public thoroughfares during the excavation work. Mitigation HAZ-1: Representative soil samples will be collected at locations throughout the project area, and analyzed for a variety of constituents at a local state certified laboratory. The samples will be assessed of their contents before transportation to, and stockpiling at the nearby Tesoro Refinery.site or a licensed facility. I Potentially j Significant Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact VIII. HYDROLOGY AND WATER QUALITY.. , Would the,project: a. Violate any water quality standards or waste discharge requirements? 1 X Page 12 of 19 Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact b. Substantially deplete groundwater supplies or interfere substantially with groundwater recharge such that there would be a net deficit in aquifer.volume or a lowering of the local groundwater table level (e.g., the production rate of pre-existing nearby wells would drop to a level which would not support existing land uses or planned uses,for which permits have been granted)? X . c. Substantially alter the existing drainage pattern of the site or area, including through the alteration of the course of a stream or river, in a manner, which would result in substantial erosion or siltation on or off-site? X d. Substantially alter the existing drainage pattern of the site or area, including through the alteration of the course of a stream or river, or substantially increase the rate or amount of surface runoff in a manner, which would result in flooding on- or off-site? X e. Create or contribute runoff water which would exceed the capacity of existing or planned storm water drainage systems or provide substantial additional sources of polluted runoff? X f. Otherwise substantially degrade water quality? X g, Place housing within a 100-year flood hazard area as mapped on a federal Flood Hazard Boundary or Flood Insurance Rate Map or other flood hazard delineation map? X h. Place within a 100-year flood hazard area structures, which would impede or redirect flood flows? X i. Expose people or structures to a significant risk of loss, injury or death involving flooding, including flooding as a result of the failure of a levee or dam? X j. Inundation by seiche, tsunami, or mudflow? X SUMMARY: Potentially Significant Unless Mitigation Incorporated. Avoidance and minimization measures will be undertaken in the design of the project to avoid adverse impacts to water quality. Contract specifications will require these measures to be implemented to ensure that sediment will not enter the waterway. A two-ft berm/buffer will be flagged around the low flow channel of both channels. The excavation project will not adversely affect the quantity or quality of surface water, ground water or public water supply. Contract specifications will also require the storage, servicing and fueling of construction equipment outside of the channel. Standard construction safety practices will be incorporated into the project to reduce the possibility of a spill of gasoline, oil, or other pollutant that could have a significant impact on water quality. In addition, sediment will be loaded on to dump trucks, and deposited at an upland site chosen at the nearby Tesoro Refinery (Figure 2.). Normal creek flows will be maintained during the desilting project, so a de- watering system will not be needed. The low flow channel will not be impacted by the excavation project, therefore no change in drainage patterns are expected. Excavation of silt deposits from the flood plain will allow the low flow channel to use it's flood plain more efficiently during high flow. The project will not create run-off of any kind to the channel, as Page 13 of 19 vegetation is expected to re-establish itself quickly after the desilt. Project work will occur at the driest part of the year. The excavationproject will-not increase exposure of people or property to'flooding. In fact, the goal of the project is to lessen the potential exposure of people and property to flooding by restoring the flood control channel to design capacity. A _ Total disturbance due to this project will be greater than an acre; therefore, in order to comply with the State ?: Water Resources Control Board National Pollutant Discharge Elimination System (NPDES) General Construction Permit requirements, a Storm Water Pollution Prevention Plan (SWPPP) will be required by the contract plans and specifications. The SWPPP will specify the Best Management'Practices that will be used during project construction to ensure water quality impacts are minimized. The SWPPP will address erosion control, sediment control, non-stormwater management, post-construction storm water management, and maintenance, inspection, and repair of the BMPs used on-site. At,the completion of the project, all disturbed areas will be stabilized through the use of hydro-seeding with a mix including native grasses. Water Quality Certification will be obtained from the San Francisco Bay Regional Water Quality Control Board (SFBRWCB) prior to construction of the project. Special conditions required by the certification will be complied with during construction in order to minimize the possibil'iity of water quality impacts. Mitigation Hydro — 1: A two-ft berm/barrier will be left between the low flow channel and construction areas in both Lower Walnut Creek and Lower Grayson. This berm will prevent sediment from entering the creek during construction, and affecting water quality. f Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact 'Incorporation Impact No Impact IX. LAND USE AND PLANNING. Would the project: a. Physically divide an established community? X b. Conflict with any applicable land use plan, policy, or regulation of an agency with jurisdiction over the project(including, but not limited to the general plan, specific plan, local coastal program, or zoning ordinance) adopted for the purpose of avoiding or mitigating an environmental effect? X c. Conflict with any applicable habitat conservation k= plan or natural community conservation plan? i, X SUMMARY: No.Impact. The project will not result in.an alteration of the present or planned.land use of the area. i Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact j Incorporation Impact No Impact X. MINERAL RESOURCES. Would the project: j Al a. Result in the.loss of availability of a known mineral resource that would be of value to the region and the residents of the state? X b. Result in the loss of availability of a locally important mineral resource recovery site delineated on a local general plan, specific plan a or other land use plan? X Page 14 of 19 �• I i SUMMARY: No impact. The construction of the project would not involve quarrying, mining, or extraction of any known regionally or locally important mineral, oil, or gas resources on site, nor would it deplete any non- renewable natural resource. Potentially Significant Potentially Unless Less than Significant Mitigation .Significant Impact Incorporation Impact No Impact XI. NOISE. Would the project result in: a. Exposure of persons to or generation of noise levels in excess of standards established in the local general plan or noise ordinance, or applicable standards of other agencies? X b. Exposure of persons to or generation of excessive ground borne vibration or ground borne noise levels? X c. A substantial permanent increase in ambient noise levels in the project vicinity above levels existing without the project? X d. A substantial,temp'orary or periodic increase in ambient noise levels in the project vicinity above levels existing without the project? X e. For a project located within an airport land use plan or, where such a plan has not been adopted, within two miles of a public airport or public use airport, would the project expose people residing or working in the project area to excessive noise levels? X f. For a project within the vicinity of a private airstrip, would the project expose people residing or working in the project area to excessive noise levels? X SUMMARY: Less Than Significant Impact. Maintenance of the flood control channel will not increase the capacity of roads in the vicinity; therefore no additional vehicle trips will be generated as a result of the implemented project. There will be a limited number of additional vehicle trips during construction resulting from worker vehicles accessing the site; however, this.will be a minor and temporary impact that would not significantly increase the ambient noise level at the project site and is, therefore, deemed less than significant. The site is bordered predominantly by commercial and industrial. properties, including an airport. Construction of the project will increase the ambient noise level near the project site temporarily. Typically, construction activities produce average noise levels of about 86 dBA at 50 feet from any given construction site. This construction project is expected to be consistent with this generalized average due to the standard construction activities that will occur. Increased noise as a result of construction activities will be temporary and will; therefore, remain at a level that is less than significant. Working hours will be limited to 7:30 am to 5 pm on weekdays. These working hours will be incorporated as part of the construction contract. Contract specifications will also require the use of properly tuned and muffled equipment to minimize noise due to construction activities. The majority of the project area is commercial with high traffic flow into and out of shopping malls, and other commercial buildings. 1-680 and Highway 4, both major freeways, are located next to the project area. The project will not add any noticeable noise to the area. i Page 15 of 19 1 1 I • I Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact XII. POPULATION AND HOUSING. Would the project: a.' Induce substantial population growth in an area, either directly (for example, by proposing new homes and businesses) or indirectly (for i example, through extension of roads or other 1 infrastructure)? ; X b. Displace substantial numbers of-existing housing, necessitating the construction of replacement housing elsewhere? i X c. Displace substantial numbers of people, necessitating the construction of replacement housing elsewhere? IX SUMMARY : No Impact. The goal of the project is to provide flood control protection to the.area.' This goal will be achieved without creating additional infrastructure that could encourage population growth. Downstream of the proposed flood control improvements (the location the project will benefit), the area is essentially built-out with industrial uses, and therefore the project will not induce further population growth. The project will not result in the displacement of any homes or'residents, nor will it result in a change in the location, distribution, density or growth rate of human population in the area. The.project will not affect existing housing, or create a demand for additional houses nor will it require the removal.of any homes or the displacement of any people. Potentially Significant Potentially. Unless Less than Significant Mitigation- Significant Impact Incorporation Impact No Impact I XIII. PUBLIC SERVICES ' a. Would the project result in substantial adverse I physical impacts associated with the provision of new or physically altered governmental facilities, need for new or physically altered governmental facilities, the construction of which could cause significant environmental impacts, in order to maintain acceptable service ratios, response -times or other performance objectives for any of the public services. 1. Fire Protection? X 2. Police Protection? i X 3: Schools? j X 4. Parks? X 5. Other Public facilities? I X I SUMMARY Less Than Significant Impact.. During construction, residents and emergency service vehicles will be able to access the construction site and all adjacent neighborhoods at all,times . Once the project is complete, the flood control maintenance project will not increase the need for fire or police protection, schools, parks or other governmental services. Periodic maintenance of the flood control Page 16 of 19 i { 4 improvements will be performed by the County to ensure the facilities are operating in a safe and effective manner. Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact XIIII. RECREATION a. Would the project increase the use of existing neighborhood and regional parks or other recreational facilities such that substantial physical deterioration of the facility would occur or be accelerated? X b. Does the project include recreational facilities or require the construction or expansion of recreational facilities, which might have an adverse physical effect on the environment? X SUMMARY: Less than Significant Impact. The excavation project is expected to have no effect on existing neighborhood parks in the area, but will temporarily affect the recreational use of the regional trail that uses the access road parallel to the Walnut Creek channel. This trail is maintained by East Bay Regional Parks, and portions of it will be closed temporarily during construction activities. Park authorities will be advised of the closure, and sections of the trail will be re-opened as soon as work in those areas is completed. Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact XV. TRANSPORTATION/TRAFFIC. Would the project: a. Cause an increase in traffic, which is substantial in relation to the existing traffic load and capacity of the street system (i.e., result in a substantial increase in either the number of vehicle trips, the volume to capacity ratio on roads, or congestion at intersections)? X b. Exceed, either individually or cumulatively, a level of service standard established by the county congestion management agency for designated roads or highways? X c. Result in a change in air traffic patterns, including either an increase in traffic levels or a change in location that results in substantial safety risks? X d. Substantially increase hazards due to a design feature.(e.g., sharp curves or dangerous inter- sections) or incompatible uses (e.g., farm equipment)? X- e. Result in inadequate emergency access? X f. Result in inadequate parking capacity? X g. Conflict with adopted policies, plans, or programs supporting alternative transportation (e.g., bus turnouts, bicycle racks)? X SUMMARY: Less Than Significant Impact. The majority of the project will take place in the flood control channels which are paralleled by access roads, and not open to cars owned by the public. The areas adjacent Page 17 of 19 1 to the flood control channels receive traffic from day use shoppers, due to the location of various box store and mini-mall locations here. Increase in traffic from construction workers will be negligible. 4 Work at the project site is estimated to take approximately 30 - 40 days. Based on the relatively small number of truck trips generated (approximately 50 per day) and the limited number of days over which the trips will occur, the impact due to the transportation of fill to the nearby Tesoro Refinery is less than significant. Off haul of sediment in the dump trucks to the nearby Tesoro Refinery (Figure 2.), will lessen the distance needed to transport the material for disposal. Traffic on adjacent roadways may need to be temporarily stopped in order to allow dump trucks and other deliveries to enter and exit the access roads at the work site.along various access points at the project site. However, impacts to traffic will be temporary and minor. All attempts will be .made to accommodate construction machinery entering and exiting the project area through County right-of-way onto.minor roads. Portions of the recreational trail that parallels Walnut Creek wiN be closed during the de-silting project. The ' East Bay Regional Parks District will be advised of the project, and will be advised of path closures. Pedestrians and bike riders using the recreational trail for alternative transportation will be temporarily affected by the project, however alternate street routes are available around the affected portion of the trail. Mitigation Traffic — 1: Traffic on adjacent roadways may need to be temporarily stopped in order to allow dump trucks and other deliveries to enter and exit the access roads at the work site along various access points at the project site..' Flaggers will be used at complicated intersections when necessary to ensure traffic impacts remain of levels that are less then significant during the project. I Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact XVI. UTILITIES AND-SERVICE SYSTEMS. i Would the project: a. Exceed wastewater treatment requirements of the applicable Regional Water Quality Control Board? X b. Require or result in the construction of new i water or wastewater treatment facilities or expansion of existing facilities, the construction or which could cause significant environmental effects? - X c. Require or result in the construction of new storm water drainage facilities or expansion of existing facilities, the construction of which could cause significant environmental effects? X d. Have sufficient water supplies available to serve the project from existing entitlement and resources, or are new or expanded entitlement needed? X e. Result in a determination by the wastewater treatment provider, which serves or may serve the project that it has adequate capacity to serve the project's projected demand in addition to the provider's existing commitments? F X f. Be served by a landfill with sufficient permitted capacity to accommodate the project's solid waste disposal needs? X g. Comply with federal, state and local statutes and regulations related to solid waste? X Page 18 of 19 j I SUMMARY: No impact. The project will not require the addition of any wastewater treatment facilities or necessitate an increase in the use of public water. There are no solid waste issues associated with the project. Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact XVII. MANDATORY FINDINGS OF SIGNIFICANCE a. Does the project have the potential to degrade the quality of the environment, substantially reduce the habitat of a fish and wildlife species, cause a fish or wildlife population to drop below self-sustaining levels, threaten to eliminate a plant or animal community, reduce the number or restrict the range of a rare or endangered plant or animal or eliminate important examples of the major periods of California history or prehistory? X b. Does the project have impacts that are individually limited, but cumulatively considerable? ("Cumulatively considerable" means that the incremental effects of a project are considerable when viewed in connection with the effects of past projects, the effects of other current projects, and the effects of probable future projects)? X c. Does the project have environmental effects, which will cause substantial adverse effects on human beings, either directly or indirectly? X SUMMARY: Less than significant impact. The excavation project will temporarily impact wetlands in Lower Grayson Creek, but will return the flood plain to elevations more conducive to the formation of perennial wetlands. Seasonal wetlands in the Grayson Creek reach of the project are frequently inundated during winter flows. The low flow channel will be protected by 2 ft berms/buffers, separating them from construction activities. Vegetation in the excavated areas is expected to regenerate quickly following hydro-seeding, and the start of the rainy season. In Walnut Creek, areas of non-wetland (uplands)will be excavated to lower elevation to where re- establishment of perennial wetlands can occur; increasing wetland habitat in the channel. Emergent Marsh, and ponded areas in Lower Walnut Creek channel will remain intact habitat and will be protected from the excavation project with 2 foot berms/buffers. The project has been designed as self-mitigating. 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U) / c = o 5 ~ f c / m/ (, \ % \ » $ � %2 § & \ n G G "\ § } 2 \ . . ° G S S \ a . 0 / } ) [ f / / $ \ om \ 2 © { . e % \ G m 7 { } / \ ' ) ® / > f 5 a 2 3 z \ \ 2 7 \ ^ $ } E / u /\ \ , 2 % a) E � \ c2LU \ \ k k \ \ k ' # 2 g m § � ® 2 \ : 2 \ n — 5 \ % 2 g ƒ \ ƒ 2 n / % \ 2 £ d \ k i0 . 2 / L Z ' : / � t / IL - 7 \ / \ \ / /z o - E . - « / « / \ / ƒ \ � c » _ ® ; } » § _ { / _ \ CL n \ g ƒ \ \ . 5 ( r CALIFORNIA ENVIRONMENTAL QUALITY ACT NOTICE OF DETERMINATION CONTRA COSTA COUNTY COMMUNITY DEVELOPMENT DEPARTMENT 651 PINE STREET 4TH FLOOR NORTH WING MARTINEZ, CALIFORNIA 94553-0095 Telephone: (925) 313-2296 Contact Person: Cece Sellgren, Environmental Planner Project Description, Common Name (if any) and Location: Lower Walnut Creek and Lower Grayson Creek Floodplain Restoration and De-Silting Project.CP# 05-30 Project #7520 689353.The project consists of floodplain restoration and de-silting excavation work in the floodplains of Lower Walnut Creek between Concord Blvd. and Drop Structure 1 (below Monument Blvd.), and Lower Grayson Creek from Highway 4 to Chipancingo Pkwy.). The low flow channel in both creeks will not be impacted during the excavation work, and will be protected by a two-foot berm/ buffer zone that will be flagged prior to start of construction. Identified non-wetland areas in Walnut Creek, and wetland areas in Lower Grayson Creek will be excavated to restore the flood plain to design elevations. To ensure that construction/excavation activities do not impact sensitive areas in the project area, temporary flagging with tape will be installed around wetland areas, the low flow channel, and ponded areas to delineate a two foot buffer zone/berm that will isolate sensitive areas from impacts during construction in Walnut Creek. Buffer zones will be established around the low flow channel of Lower Grayson Creek. County staff will instruct the contractor on installation of the buffer zone, and will be diligent with making sure that the buffer zone is strictly respected during construction. It will be necessary to construct approximately 8 -10 temporary access ramps from the access road at the top of the flood control channel into the Lower Walnut Creek floodplain for machinery access during construction. These temporary ramps will be made of material excavated from the non-wetland areas of the floodplain, and will be removed after the project is complete. Each ramp will require approximately 125 cubic yards of material, and will extend from the top of the trapezoidal channel into the flood plain. Avoidance and minimization measures will be incorporated into the project to ensure that environmental impacts are kept to a less than significant level. The project was approved on Pursuant to the provisions.of the_California.Environmental Quality Act: ❑ An Environmental Impact Report was prepared and certified (SCH # ) ❑ The Project was encompassed by an Environmental Impact Report previously prepared for (SCH # ). ® A Negative Declaration was prepared Copies of the record of project approval and the Negative Declaration or the final EIR may be examined at the office of the Contra Costa County Public Works Department. ® The Project will not have a significant environmental effect. ❑ The Project will have a significant environmental effect. ® Mitigation measures were made a condition of approval of the project. ❑ A statement of overriding considerations was adopted. ❑ Findings were adopted pursuant to Section 15091 of the State CEQA Guidelines. Date: By: Community Development Department Representative AFFIDAVIT OF FILING AND POSTING I declare that on I received and posted this notice as required by California Public Resources Code Section 21152(c). Said notice will remain posted for 30 days from the filing date. Signature Title l Applicant: Department of Fish and Game Fees Due Public Works Department ❑ EIR-$850 Total Due: $$1,300 255 Glacier Drive ® Neg. Dec.-$1,250 Total Paid $ Martinez, CA 94553 ❑ DeMinimis Findings-$0 Attn: ® County Clerk-$50 Receipt#: CALIFORNIA ENVIRONMENTAL QUALITY ACT NOTICE OF DETERMINATION CONTRA COSTA COUNTY COMMUNITY DEVELOPMENT DEPARTMENT 651 PINE STREET 4TH FLOOR NORTH WING MARTINEZ, CALIFORNIA 94553-0095 Telephone: (925) 313-2296 Contact Person: Cece Seligren, Environmental Planner Project Description, Common Name (if any) and Location: Lower Walnut Creek and Lower Grayson Creek Floodplain Restoration and De-Silting Project. CP# 05-30 Project #7520 6139353. The project consists of floodplain restoration and de-silting excavation work in the floodplains of Lower Walnut Creek between Concord Blvd. and Drop Structure 1 (below Monument Blvd.), and Lower Grayson Creek from Highway 4 to Chipancingo Pkwy.).The low flow channel in both creeks will not be impacted during the excavation work, and will be protected by a two-foot berm/buffer zone that will be flagged prior to start of construction. Identified non-wetland areas in Walnut Creek, and wetland areas in Lower Grayson Creek will be excavated to restore the flood plain to design elevations. To ensure that construction/excavation activities do not impact sensitive areas in the project area, temporary flagging with tape will be installed around wetland areas,the low flow channel, and ponded areas to delineate a two foot buffer zone/berm that will isolate sensitive areas from impacts during construction in Walnut Creek. Buffer zones will be established around the low flow channel of Lower Grayson Creek. County staff will instruct the contractor on installation of the buffer zone, and will be diligent with making sure that the buffer zone is strictly respected during construction. It will be necessary to construct approximately 8 - 10 temporary access ramps from the access road at the top of the flood control channel into the Lower Walnut Creek floodplain for machinery access during construction. These temporary ramps will be made of material excavated from the non-wetland areas of the floodplain, and will be removed after the project is complete. Each ramp will require approximately 125 cubic yards of material, and will extend from the top of the trapezoidal channel into the flood plain. Avoidance and minimization measures will be incorporated into the project to ensure that environmental impacts are kept to a less than significant level. The project was approved on Pursuant to the provisions-of the-California Environmental Quality Act: ❑ An Environmental Impact Report was prepared and certified (SCH# ) ❑ The Project was encompassed by an Environmental Impact Report previously prepared for (SCH# ). ® A Negative Declaration was prepared Copies of the record of project approval and the Negative Declaration or the final EIR may be examined at the office of the Contra Costa County Public Works Department. ® The Project will not have a significant environmental effect. ❑ The Project will have a significant environmental effect. ® Mitigation measures were made a condition of approval of the project. ❑ A statement of overriding considerations was adopted. ❑ Findings were adopted pursuant to Section 15091 of the State CEQA Guidelines. Date: By: Community Development Department Representative AFFIDAVIT OF FILING AND POSTING I declare that on I received and posted this notice as required by California Public Resources Code Section 21152(c). Said notice will remain posted for 30 days from the filing date. Signature Title Applicant: Department of Fish and Game Fees Due Public Works Department ❑EIR-:$850 Total Due: $$1,300 255 Glacier Drive ® Neg. Dec.-$1,250 Total Paid $ Martinez, CA 94553 ❑ DeMinimis Findings-$0 Attn: ® County Clerk-$50 Receipt#: Public Comments of PL STATE OF CALIFORNIA Governor's Office of Planning and Research q O tIFOPPIF •�l�Y`\�' State Clearinghouse and Planning Unit �OFCp Arnold Sean Walsh' Schwarzenegger Director Governor April 20,2006 Came Dovzak 2� 2006 X00 Contra Costa County Community Development �pNG\�okh pCPARfM�P1t 651 Pine Street pugvk 4th Floor,North Wing Martinez,CA 94553 Subject: Lower Walnut Creek and Lower Grayson Creek Floodplain Restoration and De-Silting Project SCH#: 2006032106 Dear Carrie Dovzak: The State Clearinghouse submitted the above named Negative Declaration to selected state agencies for review. On the enclosed Document Details Report please note that the Clearinghouse has listed the state agencies that reviewed your document. The review period closed on April 19,2006,and the comments from the responding agency(ies)is(are)enclosed. If this comment package is not in order,please notify the State Clearinghouse immediately. Please refer to the project's ten-digit State Clearinghouse number in future correspondence so that we may respond promptly. Please note that Section 21104(c)of the California Public Resources.Code states that: "A responsible or other public agency shall only make substantive comments regarding those activities involved in a project which are within an area of expertise of the agency or which are required to be carried out or approved by the agency. Those comments shall be supported by specific documentation." These comments are forwarded for use in preparing your final environmental document. Should you need more information or clarification of the enclosed comments,we recommend that you contact the commenting agency directly. This letter acknowledges that you.have complied with the State Clearinghouse review requirements for draft environmental documents,pursuant to the California Environmental Quality Act. Please contact the State Clearinghouse at(916)445-0613 if you have any questions regarding the environmental review process. Sincerely, Terry Rob s Director,State Clearinghouse Enclosures cc Resources Agency 1400 TENTH.STREET P.O.BO% 3Q44 SACRAMENTO,CALIFORNIA 95812-3044 TEL(916)445-0613 PAX(916)323-3018 www.opr.ca.gov Document Details Report State Clearinghouse Data Base SCH# 2006032106 Project Title Lower Walnut Creek and Lower Grayson Creek Floodplain Restoration and De-Silting Project Lead Agency Contra Costa County Community Development Type Neg Negative Declaration Description Project includes desilt of selected areas in Lower Walnut Creek and Lower Grayson Creek,to restore capacity in the flood control. Lead Agency Contact Name Carrie Dovzak Agency Contra Costa County Community Development_ Phone (925)313-2190 Fax email Address 651 Pine Street 4th Floor, North Wing City Martinez State CA Zip 94553 Project Location County Contra Costa City Concord, Pleasant Hill Region Cross Streets Willow Pass Road, Chipancingo Parkway Parcel No. Rancho M DD Township Range Section Base Proximity to: Highways 1-680 Airports Concord Railways Waterways Walnut Creek,Grayson Creek Schools- Land Use Public Space Project Issues AestheticNisual;Air Quality;Archaeologic-Historic; Flood Plain/Flooding; Geologic/Seismic; Noise; Soil Erosion/Compaction/Grading;Toxic/Hazardous;Traffic/Circulation;Vegetation;Water Quality; Wetland/Riparian;Wildlife Reviewing Resources Agency; Regional Water Quality Control Board, Region 2; Department of Parks and Agencies Recreation; Native American Heritage Commission; Office of Historic Preservation; Department of Fish and Game, Region 3;Department of Water Resources;California Highway Patrol;Caltrans, District 4; San Francisco Bay Conservation and Development Commission; Caltrans, Division of Aeronautics; Department of Toxic Substances Control; State Water Resources Control Board, Division of Water Quality Date Received 03/21/2006 Start of Review 03/21/2006 End of Review 04/19/2006 Note: Blanks in data fields result from insufficient information provided by lead agency. Department of Toxic Substances Control Maureen F. Gorsen, Director Alan C.Lloyd,Ph.D. 700 Heinz Avenue, Suite 200 Arnold Schwa¢eneggi Agency Secretary Berkeley, California 94710-2721 Governor Cal/EPA April '14, 2006 Ms. Carrie Dovzak V e \ APR 1 9 2006 Contra Costa County Public Works Department STATE CLEARING HOUSE 255 Glacier Drive Martinez, California 94553 Dear Ms. Dovzak: The Department of Toxic Substances Control (DTSC) has reviewed the Initial Study (IS) of February 9, 2006 and Notice of Public Review and Intent to Adopt a Proposed Mitigated Negative Declaration (MND) of March 16, 2006 for the Lower Walnut Creek and Lower Grayson Creek Floodplain Restoration and De-silting Project.(SCH -#2006032106). As you may be aware, DTSC oversees the cleanup.of hazardous substance release sites and regulates hazardous waste pursuant to the California Health and Safety Code, Division 20, Chapters 6.5 and 6.8. As a potential Responsible Agency, DTSC is submitting comments to ensure that the California Environmental Quality Act (CEQA)documentation prepared for this project adequately addresses any management of hazardous waste and remediation of hazardous substance releases that might be required as part of the project. The IS indicates on page 12 in the Hazards and Hazardous Materials section that sediments to be disturbed and/or moved in the course of work at the project site have the potential to contain hazardous materials, such as metals or hydrocarbons.. Sediments removed from the floodplain are to be stockpiled and disposed at the Tesoro Refinery if they meet the facility's criteria. More specific information needs to be provided on the approach or procedures that will be followed in sampling, handling, and making a determination on the proper disposal of the sediments. The information that should be provided includes: 1) the contaminants potentially present in the sediments to be removed and the analyses that are to be performed for the samples-collected from the floodplain and stockpiles at the Tesoro Refinery or how the appropriate analyses will be determined;2) the frequency and location of samples and methods for sample collection; 3) whether sediments from areas in the floodplain with relatively higher concentrations of contaminants will be segregated and handled following different procedures and with separate stockpiles; and 4) the specific criteria or types of criteria that will be used to determine the appropriate handling and disposal of the sediments. Prinfurl nn Dcrvrlo.l D....... Ms. Carrie Dovzak April 14, 2006 Page 2 Hazardous waste management regulations for the State of California may be reviewed by following the "Laws, Regs& Policies" link on the DTSC website (www.dtsc.ca.gov). Please contact Eileen.Belding at (510) 540-3844 if you have any questions. Thank you in advance.for your,consideration of our comments. Sincerely, Wit Mark Piros, P.E., Unit Chief Northern California - Coastal Cleanup Operations Branch cc: Governor's Office of Planning and Research State Clearinghouse P. O. Box 3044 Sacramento, California 95812-3044 Guenther Moskat CEQA Tracking Center Department of Toxic Substances Control P.O. Box 806 Sacramento, California 95812-0806 1 . i t 1' I i i 04/05/2006 09:25 5102865559 CALTRANS PAGE 01 STATE OF PRNL6­11LMINESS-MANSPOITATIONO E DEPARTMENT OF TRANSPORTATION 111 GRAND AVENUE P.O. BOX 23660 0 OAKLAND, CA 94623-0660 Fle:your power! PHONE(610)286-6505 Be energy effiicientl FAX(510)286-5559 TTY(800)735-2929 i RECEIVED yeq �e April 5, 2006 APR 0 5 2006 STATE CLEARING HOUSE CC680552 CC-680-R18.71 SCH2006032106 Ms. Carrie Dovzak Planner I[ Contra Costa County Public Works Department 255 Glacier Drive Martinez, CA 94553 Dear_Ma._Dovzak: Lower Walnut Creek and Lower Grayson Creek Floodplain Restoration and De- Silting Project—Intent to Adopt a Proposed Mitigated Negative Declaration Thank youfor including the California Department of Transportation (Department) in the early stages of the environmental review process for the Lower Walnut Creek and Lower Grayson Creek Floodplain Restoration and De-Silting Project_ We have reviewed the Intent to Adopt a Proposed Mitigated Negative Declaration and have the following comments to offer: Encroachment Permit Work that encroaches onto the State ROW requires an encroachment permit that is issued by the Department. Traffic-related mitigation measures will be incorporated into the construction plans during the encroachment permit process. See the following website link for more information: hE!p://WwW.dot.ca.gov/hg/traffogs/developserv/Mrmits/ To apply for an encroachment permit, submit a completed encroachment permit application, environmental documentation, and five (5) sets of plans (in metric units) which clearly indicate State Right of Way to: ! I I, 'Caltrans improuee mobility across California' 04/05/2006 09:25 5102865559 CALTRANS PAGE 02 Ms.Curic 1?ovzak April 5,2406 Page 2 Department of Transportation Office of Permits Attn: Sean Nozzari 111 Grand Avenue, 6'Floor Oakland, CA 94612 Should you require further information or have any questions regarding this letter, please call Christian Bushong of my staff at (510)286,5606. Sincerely, J� TIMOTHYI. SABLE District Br ch Chief IGR/CEQA c: State Clearinghouse `Caltrans improves mobility across California' STATE OF CALIFORNIA—BUSINESS TRANSPORTATION AND HOUSING AGENCY ARNOLD SCHWARZENEGGER,Governor DEPARTMENT OF TRANSPORTATION 0DIVISION OF AERONAUTICS—M.S.#40 1120 N STREET P. O.BOX 942873 Flex your power! SACRAMENTO,CA 94273-0001 Be energy efficient! PHONE (916)654-4959 FAX (916)653-9531 TTY(916)651-6827 April 19, 2006 Ms. Carrie Dovzak Contra Costa County Community Development Department 651 Pine Street Martinez, CA 94553 Dear Ms. Dovzak: Re: Contra Costa's Negative Declaration for the Lower Walnut Creek and Lower Grayson Creek Floodplain Restoration and De-Silting Project; SCH#2006032106 The California Department of Transportation (Caltrans), Division of Aeronautics (Division),reviewed the above-referenced document with respect to airport-related noise and safety impacts and regional aviation land use planning issues pursuant to the California Environmental Quality Act (CEQA). The Division of Aeronautics has technical expertise in the areas of airport operations safety and airport land use compatibility. We are a funding agency for airport projects and we have permit authority for public use airports and heliports. We offer the following comments for your consideration. The proposal consists of floodplain restoration and de-silting excavation work in the floodplains of Lower Walnut Creek between Concord Boulevard and Drop Structure 1 L(below Monument Boulevard), and Lower Grayson Creek from Highway 4 to Chipancingo Parkway. The project site is located in the vicinity Buchanan Field Airport. The proposal includes plans for the "re-establishment of perennial wetlands" on approximately seven acres. Land use practices that attract or sustain hazardous wildlife populations on or near airports can significantly increase the potential for wildlife-aircraft collisions. The Federal Aviation Administration (FAA) recommends that wetlands and other uses that have the potential to attract wildlife be restricted in the vicinity of an airport. FAA Advisory Circular (AC) 150/5200-33A entitled "Hazardous Wildlife Attractants on or Near Airports" at http://faa.gov/airports_airtraffic/airports/- resources/advisory circulars/media/150-5200-33A/150 5200 33a.jdf addresses these.issues. For additional information concerning wildlife damage management, you may wish to contact the United States Department of Agriculture, Wildlife Services, at (916) 979-2675. The proposal should be submitted to the Contra Costa County Airport Land Use Commission (ALUC) for review. The applicant should coordinate closely with airport staff to monitor wildlife activity and to ensure compatibility with future as well as existing airport operations. The protection of airports from incompatible land use encroachment is vital to California's economic future. Buchanan Field Airport is an economic asset that should be protected through effective airport land use compatibility planning and awareness. Although the need for compatible and safe land uses near airports in California is both a local and a state issue, airport staff, airport land use commissions and airport land use compatibility plans are key to protecting an airport and the people residing and "Caltrans improves mobility across California" Ms. Carne Dovzak April 20, 2006 Page 2 working in the vicinity of an airport. Consideration given to the issue of compatible land uses in the vicinity of an airport should help to relieve future conflicts between airports and their neighbors. These comments reflect the areas of concern to the Caltrans Division of Aeronautics with respect to airport-related noise and safety impacts and regional airport land use planning issues. We advise you to contact our District 4 Office in Oakland at (510) 286-4444 concerning surface transportation issues. Thank you for the opportunity to review and comment on this proposal. If you have any questions, please call me at (916) 654-5314. Sincerely, �Cd Z� SAND�YIfi�SNARD Aviation Environmental Planner c: State Clearinghouse, Buchanan Field Airport, Contra Costa County ALUC `Caltrans improves mobility across California' EAST BAY MUNICIPAL UTILITY DISTRICT April 10, 2006 Carrie Dovzak, Planner II Contra Costa County Public Works Department 255 Glacier Drive Martinez, CA 94553 Re: Proposed Mitigated Negative Declaration—Lower Walnut Creek and Lower Grayson Creek Floodplain Restoration and De-silting Project, Contra Costa County Dear Ms. Dovzak: East Bay Municipal Utility District(EBMUD) appreciates the opportunity to comment on the Mitigated Negative Declaration for the Lower Walnut Creek and Lower Grayson Creek Floodplain Restoration and De-silting Project located in Contra Costa County. The project is located outside of EBMUD's Ultimate Service Boundary and does not affect any EBMUD facility; therefore, EBMUD has no comments regarding environmental issues for this project. If you have any questions concerning this response,please contact David J. Rehnstrom, Senior Civil Engineer, Water Service Planning at (510) 287-1365. Sincerely, eanager ik atric P of Water Distribution Planning WRK:NJR:sb sb06 102.doc 375 ELEVENTH STREET. OAKLAND. CA 94607-4240. TOLL FREE 7-866-40-EBMUD aecynea vepa, 04/21/06 16;40 FAX 9256713381 concordPermitCenter 12 001 TRANSMITTAL Concord City of Concord Department of Economic Development &Planning Planning Division 1950 Parkside Drive, MS/53 Concord, California 94519 Phillip Woods 925/671-3284 Fax: 925/671-3381 Date: April 21, 2006 To: Ms. Came Dovzak Planner II Contra Costa County Public Works Department 255 Glacier Drive Martinez, CA 94553-4897 Fax no.:-(925) 313-2333 Subject:City of Concord's Comments on the Mitigated Negative Declaration for the Lower Walnut Creek and Grayson Creek Floodplain Restoration and De-Silting Project(County File No. CP 05-30) 5 pages including this page. Please find attached the City of Concord's Comments on the Mitigated Negative Declaration for the Lower Walnut Creek and Grayson Creek Floodplain Restoration and De-Silting Project 4u Phillip Woods 04/21/06 16:40 FAX 9256713381 ConcordPermitCenter Z002 TRANSMITTAL Concord City of Concord Department of Economic Development &PIanning Planning Division 1950 Parkside Drive,MS/53 Concord, California 94519 Phillip Woods 925/671-3284 Fax: 925/671-3381 Date: April 21, 2006 To: Carl Roner Contra Costa County Public Works Department 255 Glacier Drive Martinez, CA 94553-4897 Fax no.: (925) 313-2333 Subject:City of Concord's Comments on the Mitigated Negative Declaration for the Lower Walnut Creek and Grayson Creek Floodplain Restoration and De-Silting Project (County File No. CP 05-30) 5 pages including this page. Please find attached the City of Concord's Comments on the Mitigated Negative Declaration for the Lower Walnut Creek and Grayson Creek Floodplain Restoration and De-Silting Project T o V v aZ� Phillip Woods 04/21/06 16:40 FAX 9256713381 ConcordPermitCenter U003 CrrY OF CONCORD bn''COUNCIL PER UT CENTER Susan A.Bonilla,Mayor 1950 Parkside Drive Mark A.Peterson,Vice Mayor Concord, California 94519-2578 Helen M.Allen Laura M.Hoffmeistcr Telephone: (925) 671-3454 W511iam D.Shinn Fat (925) 671-3381 _ biar}'Rae Lehman,City Clerk Thomas Wending,City Treasurer Lydia E.Du Borg,City Manager April 21, 2006 VIA FAX: (925) 313-2333 (Hard copy via regular mail) Ms. Carrie Dovzalc Planner II Contra Costa County Public Works Department 255 Glacier Drive Martinez, CA 94553-4897 RE: City of Concord's Comments on the Mitigated Negative Declaration for the Louver Walnut Creek and Grayson Creek Floodplain Restoration and De-Silting Project (County File No. CP 05-30) Dear Ms. Dovzak: The City of Concord has received the Notice of Public Review and Intent to Adopt a Proposed Mitigated Negative Declaration and the accompanying Initial Study for the Lower Walnut Creek and Grayson Creek Floodplain Restoration and De-Silting Project. The project consists of floodplain restoration and de-silting excavation work in the floodplains of Lower Walnut Creek between Concord Boulevard and Drop Structure No. 1 (below Monument Boulevard) and Lower Grayson Creek from Highway 4 to Chipancingo Parkway. It is our understanding that Contra Costa County is soliciting comments from the City of Concord to determine the adequacy of the environmental document. The City has contacted and requested additional information from the Contra Costa County Public Works Department to allow the City to complete its assessment of the Initial Study. A meeting has been scheduled 'for Monday, April 24, 2006 with staff from both the City of Concord and Contra Costa County to go over the information requested and the items presented in this letter. The City would request that the Public Comment Period for the Initial Study be extended to allow time for the City's review of new information that is received from this meeting. Based on the information received so far, the City has evaluated the Initial Study and is providing written comments that outline issues and concerns that significantly demonstrate adverse impacts to the City of Concord. The comments provided in this letter are to indicate the e-mail.• cityinfo@ci.concord.ca.us • website:xn cv.cityofconcord.org 04/21/06 16:40 FAX 9256713381 ConcordPermitCenter 004 Ms. Came Dovzak April 21,2006 Pace 2 of issues and concerns that would need to be addressed with adequate mitigation measures in the final application. Initial Study • The Initial Study states in the Recreation section that the project will have "... no effect on existing neighborhood parks in the area, but will temporarily affect the recreational use of the regional trail ..." This section should identify the traffic impacts and parking effects on Waterworld. • The project description in the April 3, 2006 letter from Neil Leary, Senior Civil Engineer with Contra Costa County Public Works Department, to Nohemi Navarro, Permit Center Technician III with the City of Concord, differs significantly with the Initial Study on the number of estimated truck haul trips. Mr. Leary's letter says the project "will generate approximately 3,700 to 5,600 loaded 40-ton California —legal truck trips ..." This averages to about 100 loaded haul trips per day. However, the Initial Study states "Based on the relatively small number of truck trips generated (approximately 50 per day) and the ]united number of days over which the trips will occur, the impact due to the transportation of fill to the nearby Tesoro Refinery is Iess than significant." This varies significantly from the information provided in the Initial Study. • Whether it is 50 or 100 loaded haul trips per day, the weight of the loaded trucks poses a potentially significant maintenance problem for City maintained streets, parking lots, curbs, and sidewalks. The weight of the trucks could cause structural damage to streets and the WaterWorld parking lot. Trucks driving over the curb and sidewalk could cause them to chip, crack, and/or break. Mitigation Measures need to be identified to mitigate the potential damage to-City property. • The Mitigated Negative Declaration states that "Flaggers will be used at complicated intersections when necessary ..." Mitigation Measure need to include provisions for flaggers to be available for tricks exiting into the roadway at all times. All flagging operations on City streets and the Waterworld parking lot must use certified flaggers. Items Needing Additional Clarification • Indicate the location of where the offhaul material is being hauled. • Indicate whether or not all areas shown on the planwill be worked on simultaneously or will worked from north to south. • Indicate whether CCCFC prepared a public notice to business in the area that will be affected by this construction. Items that Require Mitigation Measures • The City has two sewer mains (30" and 18") crossing the Walnut Creek Channel. They are in the area delineated as N and M on the plans. Extreme caution is required in this a 04/21/06 16:41 FAX 9256713381 ConcordPermitCenter 0005 Ms, Carrie Dovzak April 21,2006 Page 3 of area. Concord Public Works would like to see the cross section of this area for the depth of the proposed de-silting. • Provide a description of operation schedule that includes time and days of week. The hours can not conflict with peak hour traffic on Concord Avenue, Meridian Park Boulevard, Diamond Boulevard, Waterworld Parkway, Willow Pass Road, and other nearby streets. • Indicate location of truck staging. Please note, the City will not allow the trucks to be lined up along sides of the roadways, especially along Waterworld Pkwy. • During operation of Waterworld Park, the parking attendants collect parking fees approximately 200 feet from Enea Circle. This causes traffic to back up along Waterworld Pkwy. A flagger will be needed in this area to guide the trucks against traffic. Contra Costa County needs to work directly with Waterworld Park. • The project description indicates construction vehicles are proposing to travel on Waterworld Parkway and through the Waterworld parking lot during its operation. During peak operation this can be a heavily congested corridor with pedestrians, bicyclists, buses, cars, and other vehicles going to and from Waterworld. A measure needs to be identified to ensure the safety of people and vehicles on the nearby streets and parking lot of the Waterworld complex. ® The road way to the pump station (at the end of Waterworld Pkwy R.O.W.) will not take this type of truck weight. At the very least 1,500 linear—feet-of the pavement will be severely damaged by the truck traffic. This will need to be repaved. All other damages to roads and infrastructure shall be restored. • The contractor needs to advance a deposit against damages. • Pictures or video of roads and structures to be used need to be provided before work starts. This should be done in conjunction with Current Development and Public Works. • During the encroachment permit application process, Contra Costa County has stated that all trucks will be "legal load." Given that the off haul will be wet materials, the City will require and conduct spot checks on the truck weights. • Once the District issue's the contract the City would like to see the contractor's location of the service area for the equipment performing the excavation. The trucks could potentially spill their haul load onto City streets and other property. The spill could ultimately go down the storm water drains, which would negate some of the 04/21/06 16:41 FAX 9256713381 ConcordPermitCenter 0 006 Ms. Carrie Dovzak April 21,2006 Page 4 of 4 benefits of the proposed project. The truck beds shall be lined and covered when traversing City streets and the Waterworld parking lot. • The City will require a street sweeper to be on and used stand-by as needed. • The traffic division has a bone pile of poles on the point at the pump station that will need Coordinated to be moved_ Thank you for the opportunity to review and comment on the Lower Walnut Creek and Grayson Creek.Floodplain Restoration and De-Silting Project. The environmental document needs to address the concerns and significant impacts that the City of Concord has identified in this letter. The City will be providing additional comments after our scheduled meeting on Monday, April 24, 2006. If you have any questions regarding these comments, or would like to discuss them further,please contact me at(925) 671-3284. Ve ly yours, Phillip Woods,AICP Principal Planner cc: Carl Rohner, Contra Costa Public Works Alex Pascual, City Engineer and Director of Building, Engineering, and Neighborhood Services Qamar Khan,Director of Public Works—Maintenance Services John Templeton, Transportation Manager Abul Hossain, Transportation Program Manager Mario Camorongan, Senior Civil Engineer Libbey Bell, Public Works Engineer III Shea Halligan,Senior Construction Inspector Nohemi Navarro, Permit Technician III 061tr.059 i EAST BAY REGIONALPARK DISTRICT 'M PAdak 1 V E D BOARD OF DIRECTO Carol Severin APR 2 4 2006 President Sent CONTRA COSTA COUNTY John Sutter April 19, 2QQ6 PUEiLfc WOR^ ,_ OEP.ARTMENT dice-President Ward 2 Carrie Dovzak Ayn Wieskamp Planner lI Treasurer Contra Costa County Public Works Dept. Ward 5 255 Glacier Drive Ted Radke Martinez Ca 94553 secretary, Ward 7 Subject: LOWER WALNUT CREEK&LOWER GRAYSON CREEK Beverly Lane � Ward 6 FLOODPLAIN RESTORATION &DESILTING PROJECT FILE NO: CP#: 05-30 Doug Siden Ward 4 Dear Ms. Dovzak: Nancy Skinner Ward 1 The East Bay Regional Parks District(the `District')has received and reviewed the Mitigated Pat O'Brien Negative Declaration (MND) for the Lower Walnut Creek and Lower Grayson Creek General Manager Floodplain Restoration and Desilting Project. The District maintains and operates the Iron Horse Regional Trail, a recreational trail, on the westerly paved access road adjacent to the Walnut Creek Channel between Concord Avenue and Diamond Boulevard in the City of Concord. The Contra Costa County Flood Control District (CCCFCD) operates a parallel unpaved access road located along the easterly portion of the Walnut Creek Channel between Concord Avenue and-Diamond Boulevard. The Environmental Checklist Form included in the Notice of Public Review and Intent to Adopt a Proposed Mitigation Negative Declaration sent to the District dated March 16, 2006 was missing all even numbered pages and therefore significant portions of the environmental analysis was not provided to the District. Our comments below are based on the pages received. However, the District requests that a complete copy of the environmental checklist be provided and that additional comments accepted based on our review of the full document once received. Pursuant to the California Environmental Quality Act (CEQA), a project would have a significant impact if it is determined that the project would increase use of recreational facilities such that substantial physical deterioration of the facility would occur or be accelerated. The proposed project intends to dramatically increase the use of this pedestrian trail by utilizing it as a staging area and a route for ingress and egress for various pieces of construction equipment and dump trucks for approximately 40 working days. The increase of use of the trail by these pieces of equipment would have the potential to result in or accelerate the physical deterioration of the pavement on the trail, thus resulting in a significant impact pursuant to CEQA. Additionally, the project will require the removal of District fencing established along the creek bank for the purpose of public safety. 2950 Peralta Oaks Court P.O. Box 5381 Oakland, CA 94505-0381 TEL 510 635-0135 F., 510 569-4319 TDD 510 633-0460 www.ebparks.org 7777=- The proposed project should be required to incorporate mitigation measures in the MND to address the likely significant impacts associated with increased use of the paved trail and removal of safety fencing and potential damage to other facilities. The District requests that the following mitigation measure be incorporated into the project: Mitigation Recreation - I: The CCCFCD must exercise reasonable care by utilizing the unpaved access road on the easterly banks of Walnut Creek during all project phases between Concord Avenue and Diamond Boulevard. If it is determined the use of the unpaved access road is not feasible, the CCCFCD must cooperate with the District to ensure that any physical damage to the paved recreational trail, safety fencing, and/or other facilities is repaired to the satisfaction of the District, or the District is adequately reimbursed for any repair costs incurred as a result of the proposed project. The Iron Horse Trail would be closed for a minimum of 40 working days (Aug. 1 to Oct. 1) due to the proposed project. Unfortunately, as mentioned above, the .District has only . received odd numbered pages, which did not include the Transportation and Circulation analysis. The Iron Horse Trail is a substantial commuter route for bicycles and pedestrians in the Central Contra Costa County region. The proposed project must adequately address the closure of this pedestrian route, and mitigation measures should be incorporated to require the CCCFCD to provide public information and signage regarding the trail closure and alternate routes. Without the analysis of the issues discussed above, and the provision of mitigation measures to adequately mitigate significant impacts to the physical deterioration and closure of recreational and commuter facilities, a fair argument could be made pursuant to CEQA that the proposed project requires a full Environmental Impact Report. The District requests that the MND be revised and recirculated to include measures that will adequately address all of the likely significant impacts associated with the Lower Walnut Creek and Lower Grayson- Creek Floodplain Restoration and Desilting Project Thank you for the opportunity to review and comment on this project. We would appreciate receiving future information about this project, including the required revised environmental analysis, as it becomes available. Please feel free to contact me at (510) 544-2607, or by email at nwennin er o)ebnarks.org, should you have any questions. Respectfully, Nancy Wenni ger Land Acquisit on Manager Cc: Mitch Avalon, Deputy Director—Contra Costa Co. Public Works. Neil Leary, Senior Civil Engineer—Contra Costa Co.Public Works Robert Doyle, Assistant General Manager-EBRPD Response to Public Comments Contra Costa County Maurice M. Shiu s ex officio Chief Engineer FLOOD CONTROL 255 Glacier Drive, Martinez, CA 94553-482 & Water Conservation District Telephone: (925) 313-2000 .�� FAX (925) 313-2333 April 26, 2006 Nancy Wenninger East Bay Regional Park District i 2950 Peralta Oaks Court Oakland, CA 94605-0381 Attn. Brian Holt Our File: Lower Walnut Creek/Lower Grayson Creek De-silting And Flood Plain Restoration Project Project Number: 7520 6B9353 Dear Ms. Wenninger: Thank you for your comments regarding the Lower Walnut Creek/Lower Grayson Creek De-silting and Flood Plain Restoration Project. We acknowledge your comments of concern regarding cooperation between the Park District and Contra Costa County on various aspects of the project scope that may affect the Iron Horse Trail, which is located along the west bank of the Lower Walnut Creek Channel, in the area being desilted this summer. As you have heard from Paul Detjens we have shifted the location of the upland areas to be desilted from the west side to the east side of Walnut Creek Channel, in the vicinity of Waterworld Parkway. This approach restricts our impacts to only the east side of the floodplain bench and avoids the impacts of crossing the active stream channel. It also means that this summer's work will not require a trail closure, nor will our contractor need to use the District's access roads where the Iron Horse Trail has been constructed. Because of this shift in the work area, we anticipate that our next desilt project will need to focus on the western floodplain bench and this future desilt project will require a temporary trail closure. While we have not yet scheduled this project, we will be sure to coordinate with the Park District at that time concerning the Iron Horse Trail. Thank you for your comments. If you have any questions about the project or this letter, please call me at (925) 313-2190 or e-mail me at cdovz@pw.cccounty.us. Thank you. Sincerely, Carrie Dovzak Planner II Environmental Services I CD:cd G:\GrpData\EngSvc\ENVIRO\Flood Control\LowerWC_GRAYDesilt\CEQA\Public comments\EBRPD_Itr.doc cc: P.Detiens—Flood Control L.Chavez-Environmental i I rt✓(!OBIT CpG4 Contra Costa County Maurice M. shiu Fgg y ex officio Chief Engineer L®®JJ COA7Am1®g�®Y� 255 Glacier Drive, Martinez, CA 94553-482` & Water Conservation District Telephone: (925) 313-2000 FAX (925) 313-2333 April 26, 2006 Sandy Hesnard Department of Transportation Division of Aeronautics 1120 N Street Sacramento, CA 94273-0001 Our File: Lower Walnut Creek/ Lower Grayson Creek De-silting And Flood Plain Restoration Project Project Number: 7520 6139353 Dear Ms. Hesnard: Thank you for your comments regarding the Lower Walnut Creek/ Lower Grayson Creek De-silting and Flood Plain Restoration Project. We acknowledge your comments of concern regarding the potential for "re-establishment of perennial wetlands" in the Walnut Creek Channel in the vicinity of the Contra Costa County's Buchanan airport. Buchanan Airport staff are employees of Contra Costa County Public Works, and have been notified of the plans to de-silt south of the airport. The current project area is located south of Concord Avenue, and extends, in selected identified areas to Drop #1, south of Willow Pass Road. The areas selected for de-silting are not adjacent to the airport, nor are they clustered in one large area, rather they are spaced intermittently along the full project limits. In fact, the airport was taken into consideration when the project was first defined, and reaches directly adjacent to the airport were not included in the final plan. Pods of areas to be desilted are interspersed with other existing wetland areas along the creek, and are not expected to substantially increase wildlife use beyond exisiting use. Landuse surrounding the reaches to be de-silted are predominantly highly urbanized commercial businesses, and not conducive to attracting large numbers of wildlife. This reach of Walnut Creek (including the reach immediately adjacent to the airport) have been previously de-silted, and there were no reports of increases in hazardous wildlife populations in the area after these projects were completed. I I Airport staff will be notified when desilting activities will occur. Thank you for your comments. If you have any questions about the project or this letter, please call me at (925) 313-2190 or e-mail me at cdovz@pw.cccounty.us. Thank you. Sincerely, Carrie Dovzak Planner II Environmental Services I I CD:cd G:\GrpData\EngSvc\ENVIRO\Flood Control\LowerWC_GRAYDesilt\CEQA\Public comments\DOT—Itr.doc cc: P.Detjens—Flood Control L.Chavez-Environmental I I 2 d Maurice M. Shiu Contra Costa County } ex officio Chief Engineer FLOOD CONTROL 255 Glacier Drive, Martinez, CA 94553-4825 !A� : & Water Conservation District Telephone: (925) 313-2000 FAX (925) 313-2333 April 24, 2006 I Mr. Mark Piros, Unit Chief Northern CA — Coastal Cleanup Operations Branch Dept. of Toxic Substances Control 700 Heinz Avenue Berkeley, CA 94710-2721 Our File: Lower Walnut Creek/ Lower Grayson Creek De-silting And Flood Plain Restoration Project Project Number: 7520 6B9353 Dear Mr. Piros: Thank you for your comments regarding the Lower Walnut Creek/ Lower Grayson Creek De-silting and Flood Plain Restoration Project. Your comments concerning the potential for encountering hazardous materials in the soil during project excavation work are well taken, and have been addressed in subsequent soil sampling performed in both the Walnut Creek and Grayson Creek channels. Soil samples were taken from a total of eight representative sampling locations chosen by myself and the consultant, Ninyo and Moore, to best represent the areas that we will be excavating. Samples were tested for CAM-17 metals (EPA6010B), Total Petroleum Hydrocarbons (EPA8015B), and BTEX (EPA8021 B). They were collected from depths ranging from 0.5 to 3.0 feet below ground surface following standard procedures for soil sampling, following instructions from the laboratory. None of the samples tested at Advanced Technology Laboratories (Signal Hill, CA) exceeded the Environmental Screening Levels (ESLs) from the San Francisco Bay Regional Water Quality Board for either residential or commercial use scenarios for disposal. Nor did they exceed the human health risk ESLs. Based on this information, the consultant concluded that the creek sediments sampled do not contain constituents that would require further remedial action. Since the samples did not exceed any regulatory limits, we will not be segregating the excavated soil for individual Istockpiles at the disposal site. 1 I The Lower Walnut Creek channel has a watershed of 93,500 acres, and is the largest watershed in Contra Costa County. The Lower Grayson Creek channel drains 11,000 acres of predominantly single family residential areas. We are unaware of any specific areas of concern along the channels and we do not anticipate concentrations of hazardous materials to be encountered in any particular area. Construction BMPs and health and safety regulations require that work will stop in an area where obvious hazardous substances are encountered, and these practices will be followed. De-silting operations in the past did not encounter problem areas, and we do not anticipate these problems occurring during this operation. Construction and erosion control BMPs will also be implemented for handling and transport of the sediment to local disposal sites. If you have any questions about the project or this letter, please call me at (925) 313-2190 or e-mail me at cdovz@pw.cccounty.us. Thank you. Sincerely, Carrie Dovzak Planner II Environmental Services I f i CD:cd G:\GrpData\EngSvc\ENVIRO\Flood ControhLowerWC_GRAYDesilt\CEQA\Public_comments\TSC_ltr.doc cc: P. Detjens—Flood Control L.Chavez-Environmental 2 i ! e - gg Contra Costa County Maurice M. Shiu ex t FLOOD CO Il ROL officio Chief Engineer 255 Glacier Drive, Martinez, CA 94553-482! •� . & Water Conservation District Telephone: (925) 313-2000 FAX (925) 313-2333 April 26, 2006 Timothy C. Sable Department of Transportation 111 Grand Avenue Oakland, CA 94623-0660 Our File: Lower Walnut Creek/ Lower Grayson Creek De-silting And Flood Plain Restoration Project Project Number: 7520 669353 Dear Mr. Sable: Thank you for your comments regarding the Lower Walnut Creek/ Lower Grayson Creek De-silting and Flood Plain Restoration Project regarding encroachment permits. Contra County Public Works staff are currently negotiating encroachment permits for our work on Grayson Creek with your staff. Thank you for your comments. If you have any questions about the project or this letter, please call me at (925) 313-2190 or e-mail me at cdovz@pw.cccounty.us. Thank you. Sincerely, ' Carrie Dovzak Planner 11 Environmental Services CD:cd G:\GrpData\EngSvc\ENVIRO\Flood Control\LowerWC_GRAYDesilt\CEQA\Public—comments\DOT2—Itr.doc cc: P.Detjens—Flood Control L.Chavez-Environmental 1 i tt✓mRa�, Contra Costa County Maurice M. Shiu FLOOD CONTROL ex officio Chief Engineer t 255 Glacier Drive, Martinez, CA 94553-482.` & Water Conservation District Telephone; (925) 313-2000 FAX (925) 313-2333 i April 27, 2006 Philip Woods, Principal Planner City of Concord - Planning Division 1950 Parkside Drive, MS/53 Concord, CA 94519 Our File: Lower Walnut Creek/ Lower Grayson Creek De-silting And Flood Plain Restoration Project Project Number: 7520 6139353, 7520 689355 Dear Mr. Woods: Thank you for your comments, and meeting with Public Works and Flood Control District staff last Monday regarding the Lower Walnut Creek/ Lower Grayson Creek De-silting and Flood Plain Restoration Project. We believe the meeting was beneficial, and I hope this letter of response will address the concerns expressed by your Division pertaining to our project. The project is the District's main priority for this summer to ensure these important facilities are ready to handle next winter's storms. The following points were discussed at the meeting, and noted in your correspondence to myself and Carl Roner(Engineer, Design group): Initial Study— Traffic impacts and parking effects on Waterworld The District has agreed to require the Contractor to excavate the northern-most and southern- most areas channel area before starting excavation directly adjacent to Waterworld. This will allow trucking operations to occur without interfering with automobile traffic from Waterworld. Work in the channel adjacent to Waterworld is expected to begin at approximately the same time that Waterworld closes weekday operations for the season —August 28th, and continue weekdays through September. Flaggers should not be necessary at this intersection if the schedule is secure, but will be required if deemed necessary by the Resident Engineer (RE) if our haul operations are ongoing during the time Waterworld is open to the public. Truck haul trips Truck haul trips are estimated ti o be approximately 66 trips per day,with each truck hauling approximately 15 cubic yards of material per truckload. Photos of the street hardscape at entrances and exits to the project will be taken by District staff to document the condition at I 1 these facilities prior to start of work. The District will require that the contractor repair any damage to the frontage improvements and pavement in the immediate vicinity of the channel access points to an equal to better condition than existed prior to this project. The County will ensure successful completion of these repairs; if necessary, through retention of monies owed the Contractor, as well as obtaining a performance bond guaranteeing the work, Trucks will be legal load, and should not significantly impact Concord streets relative to the usual commercial and industrial traffic that occur in this area. Items needing clarification Offhaul material location will be determined by the contractor. A disposal site in Martinez has been identified for approximately 20,000 cubic yards, but disposal of the material is at the Contractor's discretion. Order of work is discussed above under the Traffic impacts and parking effects on Waterworld section. The contractor will complete work at the northern-most and southern-most areas before beginning the excavation adjacent to Waterworld. As per CEQA guidelines, businesses adjacent to the channel were sent a copy of our Notice of Intent/Notice of Public Review on March 21, 2006. Items that require Mitigation Measures Sewer Mains— Public Works will illustrate the location of the two Concord sewer mains on the project plans, and will require the Contractor to minimize truck traffic over the sewer lines by avoiding excavating th area over the sewer until the entire area north of the lines have been excavated to final grade, avoiding excessive vibration in the area of the mains. In addition, we will specify that a 5 foot layer of sediment be left on top of the mains until excavation in the surrounding area is completed. At no time will less than 2 feet of cover be provided over the top of the sewers. Operation Schedule-Working hours are scheduled to be Monday to Friday 7 a.m. to 6 p.m. Changes to the schedule, including Saturday schedules, must be agreed to by the onsite RE before implemention. Staging-Staging areas will be located on District Right-of-Way, which includes the District maintenance road on the east side of the channel. Trucks will not line up on City streets. Traffic and Flagger issues at Waterworld, and other entrances- The project area has changed slightly, and will not include excavation on the west side of the Walnut Creek channel. This eliminates some of the entrance land exit, and traffic concerns that you expressed regarding traffic on Meridian Parkway in your correspondence. Access roadways at Diamond Lane and Via de Mercados have traffic signals where trucks enter onto busier roadways eliminating the need for flaggers at these intersections. The areas to be excavated adjacent to Waterworld will be accessed through the District's driveway off of Waterworld Parkway, south of the Waterworld entrance gate, and will not impact the roadway to the City's pump station, and will not access the Waterworld parking lot. Similarly, the northern-most area will be accessed through District right- of-way via Via Mercados. Directlaccessfrom the channel to Concord Avenue will not be allowed. Damages to roads and structures—These issues are addressed above under Truck haul trips. 2 The County's contractor will not be required to advance a deposit against damages as agreed in the meeting on Monday. Potential for trucks to spill their haul load onto City streets - Many of your concerns expressed in our meeting concerning spillage and tracking of sediment (which has the most potential to occur during transport)will be adequately addressed in the Contractor's Stormwater Pollution Prevention Plan (SWPPP)that is required for this project (under the County's NPDES permit). The SWPPP document will be reviewed by staff in the environmental group at CCC Public Works, and the RE assigned to the project has the responsibility of making sure the SWPPP is adhered to. The SWPPP includes construction and erosion control Best Management Practices (BMP's)that the contractor must implement before, during and after the project. We do not anticipate that the excavated sediment will be saturated; therefore, in our meeting we agreed that trucks will not require liners when carrying their loads. Bone pile location—Construction will not access the area near the City's pump station. We hope that this letter addresses all of your concerns. Please feel free to contact our offices with any concerns that occur during construction. Per our meeting on April 24, 2006 our two agencies were in agreement that project concerns had been addressed; therefore we have not extended the public review period for the CEQA document. If you have any questions about the project or this letter, please call me at(925)313-2190 or e-mail me at cdovz@pw.cccounty.us. Thank you. Sincerely, ;. Carrie Dovzak Planner 11 - Environmental Services Mcd G:\GrpData\EngSvc\ENVIRO\Flood Control\LowerWC_GRAYDesilt\CEQA\Public—comments\Concord—Itr.doc cc: P.Detjens-Flood Control L.Chavez-Environmental N.Leary—Design H.Ballenger-Admin I 3 Community Dennis M.Barry,AICP Contra Community Development Director Development Costa Department County l County Administration Building ' ]DEP 651 Pine Street .I4th Floor, North WingMartinez, California 94553-0095MAR 10Phone: S.L. WEIR, COUNTYCONT A ST CMarch 16, 2006 BY NOTICE OF PUBLIC REVIEW AND INTENT TO ADOPT A PROPOSED MITIGATED NEGATIVE DECLARATION County File# CP 05-30 Pursuant to the State of California Public Resources Code and the "Guidelines for Implementation of the California Environmental Quality Act of 1970" as amended to date, this is to advise you that the Community Development Department of Contra Costa County has prepared an initial study on the following project: Lower Walnut Creek and Lower Grayson Creek Floodplain Restoration and De- Silting Project, CP#: 05-30 The project consists of floodplain restoration and de-silting excavation work in the floodplains of Lower Walnut Creek between Concord Blvd. and Drop Structure 1 (below Monument Blvd.), and Lower Grayson Creek from Highway 4 to Chipancingo Pkwy.). The low flow channel in both creeks will not be impacted during the excavation work, and will be protected by a two-foot berm/ buffer zone that will be flagged prior to start of construction. Identified non-wetland areas in Walnut Creek, and wetland areas in Lower Grayson Creek will be excavated to restore the flood plain to design elevations. Removal of silt from the floodplains of both Lower Walnut Creek channel and Lower Grayson Creek Channel will be conducted with the use of excavators, and /or front end loaders working in the floodplain loading dump trucks. The excavators will only be present in the non-wetland areas of the Lower Walnut Creek channel, but will be in the flood plain area of the Lower Grayson Creek Channel containing seasonal wetlands. The excavators and dump trucks will access the site from adjacent access roads (located at the top of the trapezoidal channel) and by temporary access ramps created throughout the project site into the floodplain. In the narrow reach between 2nd Ave. S and Chilpancingo Pkwy. a long-reach excavator may be used from the top of bank to remove silt deposits identified here. Other construction equipment (e.g. general use pickup trucks, etc.) will be used as necessary. A number of avoidance and minimization measures have been included in the project to avoid impact to special status species including: 1) establishing a two-ft. buffer (berm) around the perimeter of the stream channel in both channels, and around ponds and selected wetlands in Walnut Creek during the project construction, 2) equipment will be properly maintained to ensure deleterious fluids are not allowed to enter the creek (or floodplain area), 3) work will be conducted during the dry season of any given year and 4) all work will avoid the low flow channels of both creeks. Public Comment Period — Thi period for accepting comments on the adequacy of the environmental document extends to April 21 , 2006. I Office Hours Monday p-aFrri at p:00 a.m.- 5:00 p.m. Office is closed the 1st. 3rd [h Fririavc of onnh mnnth I ANY COMMENTS SHOULD BE IN WRITING AND SUBMITTED TO THE FOLLOWING ADDRESS: Carrie Dovzak, Planner II Contra Costa County Public Works Department 255 Glacier Drive Martinez, CA 94553 The.,,,environmental document is expected to go before the County Board of Supervisors on or around May 2, 2006. To confirm the Board date, please caritact,CarrtetDov„zak ate{925) 313 2 ,90E Any questions regarding the project itself, should be directed to: 14 Paul Detjens, (925) 313-2394 Contra Costa County Public Works Department 255 Glacier Drive Martinez, CA 94553 G:\GrpData\End$vc\ENVIRO\Long Term Projs\Public_wks_expansion\CEQA\Notice of Public Review L'etter,doc Cc: County Clerk's Office Public Works— P.Detjens,FC C.Dovzak-Enviro ,i Page 2 of CONTRA PUBLIC WORKS DEPARTMENT COSTA INITIAL STUDY COUNTY OF ENVIRONMENTAL SIGNIFICANCE PROJECT WO# 9353 CP# 05-30 PROJECT NAME: Lower Walnut Creek and Lower Grayson Creek Floodplain Restoration and De-silting Project PREPARED BY: Carrie Dovzak DATE: February 9, 2006 APPROVED BY: %r DATE: i f' RECOMMENDATIONS: ( ) Categorical Exemption (Class ) (j Negative Declaration ( ) Environment Impact Report Required (X) Mitigated Negative Declaration The project will not have a significant effect on the environment. The recommendation is based on the following: There is no substantial evidence that the project or any of its aspects may cause a significant effect on the environment (Sec. 15063(b)(2)). What changes to the project would mitigate the identified impacts. N/A USGS Quad Sheet Walnut Creek Base Map Sheet# G-13, 14; H-13,14; J-13,14 Parcel # n/a GENERAL`CONSIDERATIONS: 1. Location: This de-silting and floodplain restoration project is located along the lower reaches of.two flood control channels Walnut Creek and Grayson Creek, in north-central Contra Costa County. The project limits are: Walnut Creek - from approximately Concord Blvd. to Drop Structure 1 (1/2 mile upstream of Willow Pass Road), and Grayson Creek from 1-680 to Chipancingo Pwy. (Figures 1, 2). 2. Project Description: Lower Walnut Creek and Lower Grayson Creek Floodplain Restoration and De-silting Project consists of sediment removal in the lower reaches of the Lower Walnut Creek and Lower Grayson Creek flood control channels, to restore the appropriate level of flood protection, and to restore the elevation of the floodplain to a more appropriate level for the stream channel to utilize it during high flow. The project will involve excavation almost exclusively with only minor amounts of temporary fill to facilitate access to the channel flood plain bench. i G:\GrpData\EngSvc\ENVIRO\Flood Control\LowerWC_GRAYDesilt\CEQA\Initial Study Cover.doc Page 1 of 2 This Initial Study addresses potential environmental impacts associated with operation of the project. 3. Does it appear that any feature of the project will generate significant public concern? [ ] yes [✓ ] no [j maybe (Nature of concern): 4. Will the project require approval or permits by other than a County agency? [X] yes [ ] no SF Region Regional Water Quality Control Board, U.S. Army Corps of Engineers, CA Dept. of Fish and Game 5. Is the project within the Sphere of Influence of any city? Yes, City of Pleasant Hill and City of Concord. G:\GrpData\EngSvc\ENVIRO\Flood'Control\LowerWC_GRAYDesilt\CEQA\Initial Study Cover.doc Page 2 of 2 i j Environmental Checklist Foran 1. Project Title: Lower Walnut Creek and Lower Grayson Creek Floodplain Restoration and De-Silting Project 2. Lead Agency Name and Address: Contra Costa County Community Development Department 651 Pine Street, North Wing - 4th Floor Martinez, CA 94553 3. Contact Person and Phone Number: Carrie Dovzak, Planner II (925) 313-2190 Contra Costa County Public Works Department 255 Glacier Drive Martinez, CA 94553 4. Project Location: The project is located in unincorporated Contra Costa County, the City of Concord, and the City of Pleasant Hill. Lower Walnut Creek and Lower Grayson Creek. (Figures 1 and 2.) 5. Project Sponsor's Name and Address: Contra Costa County Public Works Dept. 255 Glacier Drive Martinez, CA 94553 6. General Plan Designation: Multiple: Open Space, PS 7. Zonin : Public/Semi-public 8. Description of Project: The project consists of floodplain restoration and de-silting excavation work in the floodplains of Lower Walnut Creek between Concord Blvd. and Drop Structure 1 (below Monument Blvd.), and Lower Grayson Creek from Highway 4 to Chipancingo Pkwy.). The low flow channel in both creeks will not be impacted during the excavation work, and will be protected by a two-foot berm/ buffer zone that will be flagged prior to start of construction. Identified non-wetland areas in Walnut Creek, and wetland areas in Lower Grayson Creek will be excavated to restore the flood plain to design elevations. Lower Walnut Creek and Lower Grayson Creek were engineered from narrow creek corridors into trapezoidal channels in the early 1960's to provide flood control for the cities and property owners along its corridor, and to expedite flood waters from the upper watershed to the Sacramento River. Several reaches were de-silted in 1993, 1995 and 1997, and have, since then, exceeded their capacity for flood control from silt deposits on their flood plains. The desilting planned will restore the flood control capacity of the channels. A CCC Flood Control and Water Conservation District(District) right of way, including District access roads, exist on both sides of the channels. The project lies within unincorporated Contra Costa County, The City of Pleasant Hill, and the City of Concord. Real Property transactions may be necessary in support of this project. 9. Surrounding Land Uses and Setting: Lower Walnut Creek and Lower Grayson Creek flow through a variety of land use, but the predominant land uses along the corridors are commercial and industrial. The commercial properties range from shopping centers and.box stores, to landfills, and an airport. While the largest percentage of land use is the airport, mixed commercial and industrial uses are also prevalent. A small percentage of the land use is single family residential housing. See Figure 2. 10. Other public agencies whose approval U.S.Army Corps of Engineers,SF District of the Regional (e.g permits, financing approval, or water Quality Control Board,California Department of Fish and Game participation agreement). i Page 1 of 19 i ENVIRONMENTAL FACTORS POTENTIALLY AFFECTED: The environmental factors checked below would be potentially affected by this project, involving at least one impact that is a "Potentially Significant Impact' as indicated by the checklist on the following pages. Land Use& Planning X Transportation/Circulation Public Services Population & Housing X Biological Resources Utilities &Service Systems Geological Problems Energy&Mineral Resources Aesthetics X Water X Hazards = Cultural Resources Air Quality Noise Recreation Mandatory Findings of No Significant Impacts Significance Identified DETERMINATION On the basis of this initial evaluation: I find that the proposed project COULD NOT have a significant effect on the environment, and a NEGATIVE DECLARATION will be prepared. I find that although the proposed project could have a significant effect on the environment, there will not be a significant effect in this case because the mitigation measures described on an attached sheet have been X added to the project. A MITIGATED NEGATIVE DECLARATION will be prepared. I find that the proposed project MAY have a significant effect on the environment, and an ENVIRONMENTAL IMPACT REPORT is required. I find that the proposed project MAY have a significant effect(s) on the environment, but at least one effect (1) has been adequately analyzed in an earlier document pursuant to applicable legal standards, and (2) has been addressed by mitigation measures based on the earlier analysis as described on attached sheets, if the effect is. a "potentially significant impact" or."potentially significant unless mitigated." An ENVIRONMENTAL IMPACT. REPORT is required, but it must analyze only the effects that remain to be addressed. I find that although the proposed project could have a significant effect on the environment, there WILL NOT be a significant effect in this case because all potentially significant effects (a) have been analyzed adegdately in an earlier EIR pursuant to applicable standards and (b) have been avoided or mitigated pursuant to that earlier r EIR, including revisions or mitigation measures that are imposed upon the proposed project. Signature Date Contra Costa County Community Development Department Print Name 5. 4 Page 2 of 19 SOURCES In the process of preparing the Checklist and conducting the evaluation, the following references (which are available for review at the Contra Costa County Community Development Department, 651 Pine Street 5th Floor-North Wing, Martinez) were consulted: 1. Contra Costa Resource Mapping System - Quad Sheet Panels—Vine Hill—Walnut Creek 2. The (Reconsolidated) County General Plan (July 1996) and EIR on the General Plan (January 1991) 3. Contra Costa County Important Farmland Map 2002, California Department of Conservation Division of Land Resources Protection 4. Field reviews by Public Works staff, Biosearch, Entrix, Natural Resouces Management, Jones and Stokes, ACOE and/or Project Description (including coordination with Design Engineer) 5. Data Summary Report for the Baseline Surveys of Anadromous Fish Habitat in Lower Walnut Creek, Contra Costa County, CA (with 11 X 17 maps) Jones and Stokes, 2004. 6. Data Collection Plan for Baseline Surveys of Anadromous Fish Habitat, and Draft Delineation of Waters of the United States, Including Wetlands, for the Lower Walnut Creek Channel Restoration Project, Concord, California—January 2005 (with 11 X 17 maps) Jones and Stokes, 2004. 7. Wildlife Habitat Assessment for the Lower Walnut Creek Channel Restoration Project— December 2004 (NRM, January 2005). 8. Botanical Report for the Lower Walnut Creek Channel Restoration Project (with 11 X 17 maps) (Jones and Stokes, January 2005)... 9. Delineation of Waters of the United States, Including Wetlands for the Lower Walnut Creek Channel Restoration Project 'Report. ACOE File number 29296S (NRM/Jones and Stokes, July 2004). 10. Contra Costa County Soils Report, Soil Conservation Service, 1977. 11. Grayson Creek Habitat Assessment—August 2005. Entrix, Inc. Walnut Creek, CA. 12. Lower Grayson Creek Project Wetland Delineation—August 2005. ACOE File number 29898S. (Preliminary jurisdictional determination) Entrix, Inc. Walnut Creek, CA. 13. ABAG Earthquake Liquefaction Maps 2001. http://www.abaci.ca.gov/bayarea/egmaps/ 14. Towill, Inc. (2004)Topographic data and digital orthophotography of Lower Walnut Creek and Lower Grayson Creek. 15. National Marine Fisheries Service — Central Valley Chinook Salmon Essential Fish Habitat— Fall Run. httr):Hswr.nmfs.noaa.gov/fall.htm 16. Map: Survey Results of post-12/31/05 storm. Water surface elevation in channels. i Page 3 of 19 1 i EVALUATION OF ENVIRONMENTAL IMPACTS: ` Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact I. AESTHETICS. Would the proposal: a. Have a substantial adverse effect on a scenic vista? X b. Substantially damage scenic resources, including, but not limited to, trees, rock, ' outcroppings, and historic buildings within a state scenic highway? X c. Substantially degrade the existing visual character or quality of the site and its surroundings: X d. Create anew source of substantial light or glare,.which would adversely affect day or r` nighttime views in the area? X SUMMARY: Less than Significant Lower Walnut Creek and Lower Grayson Creek channels were designed to provide flood protection for low lying areas adjacent to and surrounding the channels in the early 1960's. The trapezoidal channels were designed void of riparian cover and vegetation to expedite flood waters through the channel to the Sacramento River. Routine maintenance of the channels keeps the channels clear of mature vegetation. Construction activities will be visible to residents living adjacent to Lower Grayson Creek channel in areas adjacent to Buchanan Airport, and south of Pacheco Blvd.; however, construction is temporary and is not expected to cause significant aesthetic impacts. The majority of the landuse in the project area is industrial and commercial. All disturbed areas will be hydro-seeded with a seed mix that includes native grasses. Construction activities are not expected to occur at night, therefore, supplemental lights will not be necessary. Following construction, the project site is expected to return to pre-project vegetated.condition. Potentially Significant r Potentially Unless Less than Significant Mitigation Significant Impact Incorporation 1.Impact No Impact IL AGRICULTURAL RESOURCES. In determining whether impacts to agricultural resources are significant environmental effects, lead agencies may refer to the California Agricultural Land Evaluation and Site Assessment Model (1997)` prepared by the California Dept. of Conservation as an optional model to use in assessing impacts on agricultural and farmland. Would the project: a. Convert Prime Farmland, Unique Farmland, or Farmland of Statewide, Importance (Farmland), as shown on the maps prepared pursuant to the Farmland Mapping and Monitoring Program of the California Resources Agency, to non- agricultural use? X b. Conflict with existing zoning for agricultural use, or a Williamson Act contract? X c. Involve other changes in the existing X Page 4 of 19 Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact environment, which, due to their location or nature, could result in conversion of Farmland, to non-agricultural use? SUMMARY: No Impact. The project will not affect any locally or statewide important farmland. The land immediately adjacent to the project consists of roadways, commercial properties, and industry. The Contra Costa County Important Farmland Map (FMMP, 2002) identifies the majority of the project as being within an area designated as "urban and built up land. The proposed project area is not currently used for agricultural purposes. Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact III. AIR QUALITY. Where available, the significance criteria established by the applicable air quality . management or air pollution control district may be relied upon to make the following determinations. Would the project: a. Conflict with or obstruct implementation of the applicable air quality plan? X b. Violate any air quality standard or contribute to an existing or projected air quality violation? X c. Result in a cumulatively considerable net increase of any criteria pollutant for which the project region is non-attainment under an applicable federal or state ambient air quality standard (including releasing emissions which exceed quantitative thresholds for ozone precursors)? X d. Expose sensitive receptors to substantial pollutant concentrations? X e. Create objectionable odors affecting a substantial number of people? X SUMMARY: Less Than Significant Impact. Short-term emissions and objectionable odors may be generated during construction; however, they will be minor and temporary. To minimize impacts due to construction activities, contract specifications will stipulate the use of properly tuned and muffled equipment and the elimination of unnecessary idling of equipment when not in use. Implementation of dust control practices including general watering of exposed areas, will be utilized to minimize air quality impacts. The minor temporary deterioration of ambient air quality during construction will end once construction is completed; therefore, there will'be no potentially adverse long-term impacts to air quality. i Page 5 of 19 7 Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact IV. BIOLOGICAL RESOURCES: Would the project: a. Have a substantial adverse effect, either directly or through habitat modifications, on any species identified as a candidate, sensitive, or special status species in local or regional plans, polices, or regulations, or by the California Department of Fish and Game or U.S. Fish and Wildlife Service? X b. Have a substantial adverse effect on any riparian habitat or other sensitive natural community identified in local or regional plans, policies, regulations or by the California Department of Fish and Game or US Fish and Wildlife Service? X c. Have a substantial adverse effect on federally protected wetlands as defined by Section 404 of the Clean Water Act(including, but not limited to, marsh, vernal pool, coastal, etc.) through direct removal, filling, hydrological interruption, or other means? X d. Interfere substantially with the movement of any native resident or migratory fish or wildlife species or with established native resident or migratory wildlife corridors, or impede the use of native wildlife'nursery sites? X e. Conflict with any local policies or ordinances protecting biological resources, such as tree preservation policy or ordinance? X f. Conflict with the provisions of an adopted Habitat Conservation Plan, Natural Community Conservation Plan, or other approved local, regional, or state habitat conservation plan? X SUMMARY: Potentially Significant Unless Mitigation Incorporated. Various studies in support of biological resources in the project area were carried out from 2003 _ 2006 which identified listed species and habitats within or adjacent to the project area that need special, consideration. A Habitat Assessment of the Lower Walnut Creek project site was conducted by Natural Resources Management (Berkeley,CA), in May 2004 to characterize the habitats present here and the likelihood of special status species occurring in the area. Similarly, a biological assessment was completed by Jones and Stokes (January, 2005). A Section 404 Clean Water Act Jurisdictional Delineation was conducted by Jones and Stokes in May 2004 and confirmed by the United States Army Corps of Engineers (USACOE) on January 21, 2005 (Corps File No. 29296S). Similar wetland and habitat studies were carried out on Lower Grayson Creek by Entrix, Inc. in August 2005. A Section 404 Clean Water Act Jurisdictional Determination was confirmed on the Lower Grayson Creek (Corps File No. 29898S) area on January 3, 2006. A wetland delineation of Lower Grayson Creek between Pacheco Blvd. and Chilpancingo Pkwy. is currently in progress. Activities associated with the project will occur within California Department of Fish and Game, Regional Water Quality Control Board, and U.S. Army Corps of Engineer's jurisdiction. Permits for the project will be obtained from these agencies. Page 6 of 19 Based on the limited habitat in the channels, and the proximity to the surrounding urban area, impact to listed species as a result of the project is unexpected. Consultants for the project have identified species that may have potential of occurrence in the project area: California red-legged frog (Rana aurora draytonii), Western pond turtle (Clemmys marmorata), Central Valley Fall run Chinook salmon and various species of birds and special status bats. Special Status Wildlife and Species of Concern California Red legged frog Based on observations by wildlife consultants working on the habitat assessments, there is a low potential for RLF habitat in the project area due to the urbanization of the area, and the presence of various predatory species identified in the creek surveys. In addition, since riparian habitat is lacking, there is limited cover for red-legged frog. Review of the CNDDB indicates the closest known sitings of RLF is approximately 5 miles away in the Martinez Hills (west), and 5 miles east in the foothills of the Mt. Diablo Watershed. These habitats are not connected to the Walnut Creek/ Grayson Creek watersheds and are separated from the project site by extensive urban and industrial landuse. Large numbers of predatory species (including mosquito fish, crayfish and bullfrogs) have been identified in portions of Walnut and Grayson Creeks as well. For these reasons RLF are not expected to be impacted by the project. Western Pond Turtle The Western Pond Turtle is a federal and state species of concern, and is a California Fully Protected species. No occurrences of westem pond turtle were observed during the habitat survey, nor are observed within 5 miles of the project site according to the CNDDB database. However, suitable habitat for the species may occur at the project site along Grayson Creek, where cattails provide cover near side channels. If any western pond turtles are found during construction, they will be relocated to an area not subject to disturbance. Mitigation Bio - 1: If any western pond turtles are found during construction, they will be relocated to an area not subject to disturbance. Birds Since the project site covers a large area, there is potential for birds to forage or nest in the site during various times of the year. Special Status birds identified as having the potential to be in the general area include California black rail, Suisun Song Sparrow, Salt Marsh Yellow Throat, White-tailed Kite and Loggerhead Shrike. Birds that prefer the Salt Marsh environment (Clapper Rail, Suisun song sparrow and Salt Marsh Yellow Throat) would prefer the northern tidally influenced portion of Lower Walnut Creek, where there are large expanses of pickleweed and tidally effected marsh land. This area is not in the project area, and no tidal marsh habitat will be impacted by the project. Landuse in the project area is predominantly urban. The channels are bordered by shopping malls, hotel complexes and dense commercial real estate. To avoid impact to nesting birds in the project area, avoidance and minimization measures will be implemented including, timing construction during the late summer, and at the end of the breeding window for these special status birds. Mitigation Bio - 2: Construction will avoid breeding season for nesting birds. Construction activities will occur in late summer in order to ensure that impacts to sensitive bird species are minimized. Nesting raptors Tall trees adjacent to the access roads above the Lower Walnut Creek Channel may be the site of nesting raptors. Avoidance and minimization measures used for nesting birds will be extended to raptor nests found near the project site. There are no mature trees in the project area that will be affected by the de-silt operation. Most mature trees near the project area:are part of landscaping for nearby malls, and parking areas which are heavily impacted by human and automobile traffic. Page 7 of 19 Mitigation Bio - 3: Same as Mitigation Bio - 2: Special-status Bat Species Several species of bats that are Federal Species of Concern may roost in bridges and nearby buildings adjacent to both Lower Grayson Creek and Lower Walnut Creek. There are four road overpasses in the project area. Suitable foraging habitat occurs adjacent to both creeks, but it .will not be affected by construction. Project construction will occur outside of the breeding times for bat species. If special status bat species are identified during construction,_the District will work with the bat specialist, as well as the California Department of' Fish and Game, to ensure the species are adequately protected. Currently there are no special-status bat species.listings in the CNDDB in the project vicinity. Fall run Chinook Salmon Since both creek corridors have been identified as possible migration routes and spawning sites for Chinook salmon, studies were carried out to identify stream characteristics in relation to spawning and rearing habitat for this protected species (Jones and Stokes, 2004, 2005. Entrix, 2005). Central Valley Fall Chinook have been observed migrating up the Walnut Creek Channel from the Sacramento River in late Fall. The District has co-sponsored several ongoing studies with ACOE (Sacramento) to assess habitat quality, and spawning success (viability of redds and eggs) in the Walnut Creek channel from the Sacramento River to the first major migration barrier (Drop#1). Although the Walnut Creek channel continues to support migration and spawning of adult Chinook salmon, the diversity and complexity of channel habitat in Lower Walnut Creek is low. The de-silting project will occur before the Fall migration up Walnut Creek channel begins, therefore there will be no salmon present during the time period of the project. The project work will occur in the dry season and avoid the stream channel. Avoidance and minimization measures to avoid impact to the stream channel, and re-establish vegetation in the flood plain after the desilt, will be implemented. These include 1) establishing a two-ft. buffer (berm) around the perimeter of the stream channel, ponds and selected wetlands during the project construction 2) construction will occur before the migration window for Fall Chinook occurs 3) equipment will be properly maintained to ensure deleterious fluids are not allowed to enter the creek (or floodplain area), 4) work will be conducted during the dry season of any given year. For these reasons, no impacts to salmonids are expected as a result of the project. Mitigation Bio - 4: Construction will avoid the low flow channel completely in the Lower Grayson Creek and Lower Walnut Creek channels. Mitigation Bio — 5: Construction will not occur during the migration window for Fall run Chinook salmon; construction will occur during the dry season. Mitigation Bio — 6: A two-ft berm/barrier will be left between sensitive wetland areas in Lower Walnut Creek and construction areas. This berm will delineate the construction areas from sensitive habitat, and will prevent impact to identified habitat.' Wetlands An ACOE confirmed wetland delineation has been completed for the Lower Walnut Creek project area (Corps File No. 29296S), and the Lower Grayson Creek (Corps File No.298980S) project area. A wetland delineation of Lower Grayson Creek between Pacheco Blvd. and Chipancingo Pkwy. is currently in progress. Areas of seasonal wetlands and emergent marsh, as well as 'Other Waters of the U.S. ' (the low flow channel and ponds) were delineated in the project area under ACOE jurisdiction. Large areas of non-wetland, were also delineated. Page 8 of 19 i A considerable amount of silt has been deposited in the Lower Walnut Creek channel since the last de-silting operation in 1997, and areas of upland within the corridor have increased. These areas were identified in the ACOE wetland confirmation as `non-wetland' (Jones and Stokes, 2005), and will be removed as part of the project to restore flood capacity within.the channel. Non—wetland areas are dominated by ruderal species such as ripgut brome, black mustard, Italian thistle, Bermuda grass and slender wild oats. Identified wetland areas within the Lower Walnut Creek channel will be protected during the de-silting operation, as will the low flow stream channel and ponds. This will leave valuable habitat intact. A two-ft buffer zone around wetland areas will ensure that sensitive areas are isolated from construction activities. Similar wetland conditions exist in the Lower Grayson corridor between 1-680 and Pacheco Blvd., and these wetlands are also within US Army Corps of Engineer's jurisdiction. Since the channel is narrower here than in Walnut Creek, and the floodplain does not exhibit upland areas of non-wetland, excavation will involve desilting within the seasonal wetlands to return the channel to design capacity. This impact will be temporary as the excavated areas of wetland here will be returned to elevations conducive to the re-establishment of perennial wetlands. The project has been specifically designed to be self-mitigating: temporary impacts to wetlands within Grayson Creek due to the desilting will be compensated for in two ways: 1) avoidance of existing wetlands on Walnut Creek and 2) reestablishment of wetlands on both Walnut Creek and Grayson Creek. 1) Avoidance of existing wetlands` Desilting activities within Lower Walnut Creek have been designed to avoid impacts to existing wetlands. Temporary flagging with tape'will be installed around wetland areas, the low flow channel, and ponded areas to delineate a two foot buffer zone/berm to isolate sensitive areas from impacts during construction. No wetland areas will be impacted by the desilting activities on Walnut Creek with the exception of 0.1 acre of temporary impact due to access road installation. 2) Reestablishment of wetlands , Approximately,7 acres of non-wetland areas in the Lower. Walnut Creek channel will be lowered to an elevation appropriate for the stream channel that is expected to support the re-establishment of perennial wetlands. Wetland areas in the Lower Grayson Creek channel will be desilted to a similar elevation, also ultimately converting the entire area into perennial wetlands. These mitigation measures will be implemented in coordination with the Army Corps of Engineers and San Francisco Bay Regional Water Quality Control Board (see attached Appendix A: Mitigation Monitoring Plan). County staff will coordinate with staff from the resource agencies regarding the project, and the appropriate agreements and permits will be obtained prior to implementation of the project. The County will comply with all conditions negotiated during the permit acquisition process. County staff is currently applying for coverage under Corps' Nationwide permit program under Section 404 of the Clean Water Acta Mitigation Bio— 7. See Mitigation Bio— 6 above. Mitigation Bio — 8: The project is designed to be self mitigating. Exisiting wetland areas in Walnut Creek will be specifically avoided by the project and areas of non-wetland in the Walnut Creek channel will be lowered to an elevation more conducive to re-establishment of perennial wetlands, compensating for the temporary impact to wetlands in Lower Grayson Creek. Wetlands impacted within Lower Grayson Creek are expected to recover rapidly as evidenced by past de-silting projects in this creek. i Potentially Significant Potentially Unless. Less than Significant Mitigation Significant Impact Incorporation Impact No Impact V. CULTURAL RESOURCES: Would the project: a. Cause a substantial adverse change in the X Page 9 of 19 Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact significance of a historical resource as defined in §15064.5? b. Cause a substantial adverse change in the significance of an archaeological resource pursuant to §15064.5? X c. ' Directly or indirectly destroy a unique paleontological resource or site or unique geologic feature? X d. Disturb any human remains, including those interred outside of formal cemeteries? X SUMMARY: Less Than Significant Impact. The channels were originally-excavated in the early-1960's, and most recently desilted in 1993, 1995 and 1997. Project specifications for the de-silting work will not allow excavation below the design level for the channel; therefore all areas that will be disturbed by the project have been previously impacted, and new findings of in-situ archaeological importance are not anticipated. Standard construction contract specifications for the project will include measures related to discovery of cultural resources, including informing personnel connected with the project of the possibility of finding archaeological and/or historical resources, requiring notification'of the Resident Engineer in the event of a discovery, and retention of a cultural resources consultant to provide assistance in the event of a discovery. In addition, the Resident Engineer for the project will receive instruction regarding identification of archaeological and historical resources in the field. In particular, the specifications will require work to be halted in the event of an archaeological discovery within 85 feet of the discovery. An archaeological consultant shall be contacted and he/she shall inspect the site before advising the resident engineer to authorize further work. Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact VI. Geology and Soils. Would the project: a. Expose people or structures to potential substantial adverse effects, including the risk of loss, injury, or death involving: . . 1. Rupture of a known earthquake fault, as delineated.on the most recent Alquist-Priolo Earthquake Fault Zoning Map issued by the State Geologist for the area or based on other substantial evidence of a known fault? Refer to Division of Mines and Geology Special Publication 42,' X 2. Strong seismic ground shaking? X 3. Seismic-related ground failure, including liquefaction? X 4. Landslides? X " b. Result in substantial soil erosion or the loss of topsoil? X c. Be located on a geologic unit or soil that is unstable, or that would become unstable as a result of the project, and potentially result in on- or off-site landslide, lateral spreading, subsidence, liquefaction or collapse? X d. Be located on expansive soil, as defined in Table 18-1-B of the Uniform Building Code X Page 10 of 19 ' I Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact (1994), creating substantial risks to life or property? e. Have soils incapable of adequately supporting the use of septic tanks or alternative waste disposal systems where sewers are not available for the disposal of wastewater? X SUMMARY Less Than Significant Impact. Exposure of people or property to geologic hazards is not expected to increase as a result of the project. Grading and excavation associated with the channel maintenance will result in a minor change in topography in the channel, and temporarily increase the exposure of soils to wind erosion. However, this is a less than significant and temporary impact. Adherence to standard dust control and erosion control practices, including, but not limited to, general watering of exposed areas will minimize impacts. Contract specifications will require flagging a two foot berm/buffer zone between the limits of excavation and identified sensitive wetlands and `other waters of the U.S.' to prevent soil from these areas during construction activities. These measures will be incorporated into the construction contract. De-silting of the project area will not result in unstable earth conditions or change geologic substructures. Exposure of people or property to geologic hazards is not expected to occur as a result of the project. In order to stabilize exposed soils, all areas.left exposed due to the de-silting work will be hydro-seeded with a mix that includes native grasses, at the earliest practicable date. Hydro-seeding will stabilize the exposed sediment in the floodplain until vegetation is naturally established. Vegetation in the floodplain is expected to establish . quickly, as it has in past de-silting operations. Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact VII. HAZARDS AND HAZARDOUS MATERIALS. Would the project: a. Create a significant hazard to the public or the environment through the routine transport, use, or disposal of hazardous materials? X b. Create a significant hazard to the public or the environment through reasonably foreseeable upset and accident conditions involving the release of hazardous materials into the environment? X c. Emit hazardous emissions or handle hazardous or acutely hazardous materials,,substances, or waste within one-quarter mile of,an existing or proposed school? X d. Be located on a site which is included on a list of hazardous materials sites compiled pursuant to Government Code Section-65862.5 and, as a result, would it create a significant hazard to the public or the environment? X e. For a project located within an airport land use plan or, where such a plan has not been adopted, within two miles of a public airport or X Page 11 of 19 I I Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact public use airport, would the project result in a safety hazard for people residing or working in the project area. f. For a project within the vicinity of a private airstrip, would the project result in a safety hazard for people residing or working in the 3 project area? X k g. Impair implementation of or physically interferes with an adopted emergency response plan or emergency evacuation plan? X h. Expose people or structures to a significant risk of loss, injury or death involving wildland fires, including where wildlands are adjacent to urbanized areas or where residences are intermixed with wildlands? X SUMMARY: Potentially Significant Unless.Mitigation Incorporated. Sediments deposited on the floodplain of Lower Walnut Creek, and Lower Grayson Creek may have the potential to contain hazardous materials (such' as concentrations of metals or hydrocarbons) that could pose a threat to the surrounding environment if not handled, or disposed'of properly. The District will create a soil sampling plan that will represent various points throughout the project area where the floodplain will be de-silted. The current plan for the excavated material entails transporting it to the nearby Tesoro Refinery and stockpiling the sediment in an upland location (Figure L 2.). Soil samples will be analyzed at a certified laboratory for various constituents identified by Tesoro Refinery before they will accept the soil for disposal. If Tesoro Refinery cannot accept the soil, it will be properly, managed and disposed of at a licensed facility. f The project has the potential to release hazardous substances, such as accidental petroleum spills from equipment, during construction. Per the contract specifications, standard construction safety practices will be followed during construction to ensure no accidental release of hazardous substances occurs and no increase in the potential for exposure to these substances occurs. There are 4 road crossings above the channel that may contain utility lines. Project designs will identify these utility and road crossings so that their locations can be clearly marked in the field, and avoided by construction activities. No interference with an emergency evacuation or response is expected to result from the project. Traffic control measures near the work area will minimize the potential for accidents. Maintenance roads parallel the project site at both creeks, enabling maintenance vehicles to avoid public thoroughfares during the excavation work. Mitigation HAZ-1: Representative soil samples will be collected at locations throughout the project area, and analyzed for a variety of constituents at a local state certified laboratory. The samples will be assessed of their contents before transportation to, and stockpiling at the nearby Tesoro Refinery site or a licensed facility. Potentially Significant Potentially 'Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact VIII. HYDROLOGY AND WATER QUALITY. Would the project: a. Violate any water quality standards or waste discharge requirements? X Page 12 of 19 ' I Potentially Significant, Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact b. Substantially deplete groundwater supplies or interfere substantially with groundwater recharge such that there would be a net deficit in aquifer volume or a lowering of the local groundwater table level (e.g., the production rate of pre-existing nearby wells would drop to a level which would not support existing land uses or planned uses for which permits have been granted)? X c. Substantially alter the existing drainage pattern of the site or area, including through the alteration of the course of a stream or river, in a manner, which would result in substantial erosion or siltation on or off-site? X d. Substantially alter the existing drainage pattern of the site or area, including through the alteration of the course of a stream or river, or substantially increase the rate or amount of surface runoff in a manner, which would result in flooding on- or off-site? X e. Create or contribute runoff water which would exceed the capacity of existing or planned storm water drainage systems or provide substantial additional sources of polluted runoff? X f. Otherwise substantially degrade water quality? X g. Place housing within a 100-year flood hazard area as mapped on a federal Flood Hazard Boundary or Flood Insurance Rate Map or other flood hazard delineation map? X h. Place within a 100-year flood hazard area structures, which would impede or redirect flood flows? X i. Expose people or structures to a significant risk of loss, injury or death involving flooding, including flooding as a result of the failure of a levee or dam? X j. Inundation by seiche, tsunami, or mudflow? X SUMMARY: Potentially Significant Unless Mitigation Incorporated. Avoidance and minimization measures will be undertaken in the design of the project to avoid adverse impacts to water quality. Contract specifications will require these measures to be implemented to ensure that sediment will not enter the waterway. A two-ft berm/buffer will be flagged around the low flow channel of both channels. The excavation project will not adversely affect the quantity or quality of surface water, ground water or public water supply. Contract specifications will also require the storage, servicing and fueling of construction equipment outside of the channel. Standard construction safety practices will be incorporated into the project to reduce the possibility of a spill of gasoline, oil, or other pollutant that could have.a significant impact on water quality. In addition, sediment will be loaded on to dump trucks, and deposited at an upland site chosen at the nearby Tesoro Refinery (Figure 2.). Normal creek flows will be maintained during the desilting project, so a de- watering system will not be needed. The low flow channel will not be impacted by the excavation project, therefore no change in drainage patterns are expected. Excavation of silt deposits from the flood plain will allow the low flow channel to use it's flood plain more efficiently during high flow. The project will not create run-off of any kind to the channel, as r Page 13 of 19 vegetation is expected to re-establish itself quickly after the desilt. Project work will occur at the driest part of the year. Tlie excavation project will not increase exposure of people or property to flooding. In fact, the goal of the project is to lessen the potential exposure of people and property to, flooding. by restoring the flood control channel to design capacity. Total disturbance due to this project will be greater than an acre; therefore, in order to comply with the State Water Resources Control Board National Pollutant Discharge Elimination System (NPDES) General Construction Permit requirements, a Storm Water Pollution Prevention Plan (SWPPP) will be required by the contract plans and specifications. The SWPPP will specify the Best Management Practices that will be used during project construction to ensure water quality impacts are minimized. The SWPPP will address erosion control, sediment control, non-stormwater management, post-construction storm water management, and maintenance, inspection, and repair of the BMPs used on-site. At the completion of the project, all disturbed areas will be stabilized through the use of hydro-seeding with a mix including native grasses. Water Quality Certification will be obtained from the San Francisco Bay Regional Water Quality Control Board (SFBRWCB) prior to construction of the project. Special conditions required by the certification will be complied with during construction in order to minimize the possibility of water quality impacts. Mitigation Hydro - 1: A two-ft berm/barrier will be left between the low flow channel and construction areas in both Lower Walnut Creek and Lower Grayson. This berm will prevent sediment from entering the creek during construction, and affecting water quality. Potentially ' Significant Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact IX. LAND USE AND PLANNING. Would the project: a. Physically divide an established community? X b. Conflict with any applicable land use plan, policy, or regulation of an agency with jurisdiction over the project (including, but not limited to the general plan, specific plan, local coastal program, or zoning ordinance) adopted for the purpose of avoiding or mitigating an environmental effect? X c. Conflict with any applicable habitat conservation plan or natural community conservation plan? X SUMMARY: No Impact. The project will not result in an alteration of the present or planned land use of the area. Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact X. MINERAL RESOURCES. Would the project: a. Result in the loss of availability of'a known mineral resource that would be of value to the region and the residents of the state? X . b. Result in the loss of availabilityof a locally important mineral resource recovery site delineated on a local general plan, specific plan or other land use plan? X Page 14 bf 19 I SUMMARY: No impact. The construction of the project would not involve quarrying, mining, or extraction of any known regionally or locally important mineral, oil, or gas resources on site, nor would it deplete any non- renewable natural resource. Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact XI. NOISE. Would the project result in: a. Exposure of persons to or generation of noise levels in excess of standards established in the local general plan or noise ordinance, or applicable standards of other agencies? X b. Exposure of persons to or generation of excessive ground borne vibration or ground borne noise levels? X c. A substantial permanent increase in ambient noise levels in the project vicinity above levels existing without the project? X d. A substantial temporary or periodic increase in ambient noise levels in the project vicinity above levels existing without the project? X e. For a project located within an airport land use plan or, where such a plan has not been adopted within two miles of a public airport or public use airport; would the project expose people residing or working in the project area to excessive noise levels? X f. For a project within the vicinity of a private airstrip, would the project expose people residing or working in the project area to excessive noise levels? X SUMMARY: Less Than Significant Impact. Maintenance of the flood control channel will not increase the capacity of roads in the vicinity; therefore no additional vehicle trips will be generated as a result of the implemented project. There will be a limited number of additional vehicle trips during construction resulting from worker vehicles accessing the site; however, this will be a minor and temporary impact that would not significantly increase the ambient noise level at the project site and'is, therefore, deemed less than significant. The site is bordered predominantly by commercial and industrial properties, including an airport. Construction of the project will increase the ambient noise level near the project site temporarily. Typically, construction activities produce average noise levels of about 86 dBA at 50 feet from any given construction site. This construction project is expected to be consistent with this generalized average due to the standard construction activities that will occur. Increased noise as a result of construction activities will be temporary and will; therefore, remain at a level that;is less than significant. Working hours will be limited to 7:30 am to 5 pm on weekdays. These working hours will be incorporated as part of the construction contract. Contract specifications will also require the use of properly tuned and muffled equipment to minimize noise due to construction activities. i The majority of the project area is commercial with high traffic flow into and out of shopping malls, and other commercial buildings. 1-680 and Highway 4, both major freeways, are located next to the project area. The project will not add any noticeable noise to the area. Page 15 of 19 is Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact XII. POPULATION AND HOUSING. Would the project: a. Induce substantial population growth in an area, either directly (for example, by proposing new homes and businesses) or indirectly (for example, through extension of roads or other infrastructure)? X b. Displace substantial numbers of existing housing, necessitating the construction of replacement housing elsewhere? X c. Displace substantial numbers of people, ". necessitating the construction of replacement housing elsewhere? X SUMMARY : No Impact. The goal of the project is to provide flood control protection to the area. This goal will be achieved without creating additional infrastructure that could encourage population growth. Downstream of the proposed flood control improvements (the location the,project will benefit), the area is, essentially built-out with industrial uses, and therefore the project will not induce further population growth. The project will not result in the displacement of any homes or residents, nor will it result in a change in the location, distribution, density or growth rate of human population in the area. The project will not affect existing housing, or create a demand for additional houses nor will it require the removal of.any homes or the displacement of any people. Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No impact XIII. PUBLIC SERVICES, a. Would'the project result insubstantial adverse physical impacts associated with the provision of new or physically altered governmental facilities, need-for new or physically altered governmental facilities, the constructionof which could cause ' significant environmental impacts, in order.to. ; maintain acceptable service ratios, response times or other performance objectives for any of the public services. 1. Fire Protection? X 2. Police Protection? X 3.' Schools? t' X , 4. Parks? ,.X 5. Other Public facilities? 'X SUMMARY Less Than Significant Impact. During construction, residents and emergency service vehicles.will be able-to access the construction site and all adjacent neighborhoods•at all times ' Once the project is complete, the flood control maintenance project will not increase the need for fire or police protection, schools, parks or other governmental services. Periodic maintenance of the flood control Page 16 of 19 improvements will be performed by the County to ensure the facilities are operating in a safe and effective manner. Potentially Significant . Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact XIIII. RECREATION a. Would the project increase the use of existing neighborhood and regional parks or other recreational facilities such that substantial physical deterioration of the facility would occur or be accelerated? X b. Does the project include recreational facilities or require the construction or expansion of recreational facilities, which might have an adverse physical effect on the environment? X SUMMARY: Less than Significant Impact. The excavation project is expected to have no effect on existing neighborhood parks in the area, but will temporarily affect the recreational use of the regional trail that uses the access road parallel to the Walnut Creek channel. This trail is maintained by East Bay Regional Parks, and portions of it will be closed temporarily during construction activities. Park authorities will be advised of the closure, and sections of the trail will be re-opened as soon as work in those areas is completed. Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact XV. TRANSPORTATION/TRAFFIC. Would the project: a. Cause an increase in traffic, which is substantial in relation to the existing traffic load and capacity of the street system (i.e., result in a substantial increase in either the number of vehicle trips, the volume to capacity ratio on roads, or congestion at intersections)? X b. Exceed, either individually or cumulatively, a level of service standard established by the county congestion management agency for designated roads or highways? X c. Result in a change in air traffic patterns, including either an increase in traffic levels or a change in location that results in 'substantial safety risks? X d. Substantially increase hazards due to a design feature (e.g., sharp curves or dangerous inter- sections) or incompatible uses (e.g., farm equipment)? X e. Result in inadequate emergency access? X f. Result in inadequate parking capacity? X g, Conflict with adopted policies, plans, or programs supporting alternative,transportation (e.g., bus turnouts,.bicycle racks)? X SUMMARY: Less Than Significant Impact. The majority of the project will take place in the flood control channels which are paralleled by access roads, and not open to cars owned by the public. The areas adjacent i Page 17 of 19 t to the flood control channels receive traffic from'day use shoppers, due to the location of various box store " and mini-mall locations here. Increase in traffic from construction workers will be negligible. i ,.. Work at the project site is estimated to take approximately 30 - 40 days. Based on the relatively small number I ,. of truck trips generated (approximately 50 per day) and the limited number of days over which the trips will i,i occur, the impact due to the transportation of fill to the nearby Tesoro Refinery is less than significant. Off haul of sediment in the dump trucks to the nearby Tesoro Refinery (Figure 2.), will lessen the distance+needed to transport the material for disposal. l Traffic on adjacent roadways may need to be temporarily stopped in order to allow dump trucks :and other j deliveries to enter and exit the access roads at the work site along various access points at the project site. However, impacts to traffic will be temporary and minor. All attempts will be made to accommodate construction machinery entering and exiting the project area through County right-of-way onto.minor roads. Portions of the recreational trail that parallels Walnut Creek will be closed during the de-silting project. The East Bay Regional Parks District will be advised of the project, and will be advised of path ;closures. Pedestrians and bike riders using the recreational trail for alternative transportation will be temporarily affected by the project, however alternate street routes are available around the affected portion of the trail. Mitigation Traffic.— 1: Traffic on adjacent roadways may need, to be temporarily stopped in order to allow. dump trucks and other deliveries to enter and exit the access roads at the work site along various access points at the project site. Flaggers will be used at complicated intersections when necessary to ensure traffic k impacts remain at levels,that are less then significant during the project. Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact XVI. UTILITIES AND SERVICE SYSTEMS. Would the project: , a. Exceed wastewater treatment requirements of the applicable Regional Water Quality Control Board? X b. Require or result in the construction of new water or wastewater treatment facilities or expansion of existing facilities, the construction or which could cause significant environmental effects? X c. Require or result in the construction of new storm water drainage facilities or expansion of existing facilities, the construction of which could cause significant environmental effects? X d. Have sufficient water supplies available to serve the project from existing entitlement and resources, or are new or expanded entitlement needed? X e. Result in a determination by the wastewater treatment provider, which serves or may serve the project that it has adequate capacity to serve the project's projected demand in addition to the provider's existing commitments? X s4, f. Be served by a landfill with sufficient permitted capacity to accommodate the project's solid waste disposal needs? °X g. Comply with federal, state and local statutes and r regulations related to solid waste? X. ; Page 18 bf 19 �7 �u SUMMARY: No impact. The project will not require the addition of any wastewater treatment facilities or necessitate an increase in the use of public water. There are no solid waste issues associated with the project. Potentially Significant Potentially Unless Less than Significant Mitigation Significant Impact Incorporation Impact No Impact XVII. MANDATORY FINDINGS OF SIGNIFICANCE a, Does the project have the potential to degrade the quality of the environment, substantially reduce the habitat of a fish and wildlife species, cause a fish or wildlife population to drop below self-sustaining levels, threaten to eliminate a plant or animal community, reduce the number or restrict the range of a rare or endangered plant or animal or eliminate important examples of the major periods of California history or prehistory? X b, Does the project have impacts that are individually limited, but cumulatively considerable? ("Cumulatively considerable" means that the incremental effects of a project are considerable when viewed in connection with the effects of past projects, the effects of other current projects, and the effects of probable future projects)? X c. Does the project have environmental effects, which will cause substantial adverse effects on human beings, either directly or indirectly? X SUMMARY; Less than significant impact. The excavation project will temporarily impact wetlands in Lower Grayson Creek, but will return the flood plain to elevations more conducive to the formation of perennial wetlands. Seasonal wetlands in the Grayson Creek 'each of the project are frequently inundated during winter flows. The low flow channel will be protected by 2 berms/buffers, separating them from construction activities. Vegetation in the excavated areas is expected regenerate quickly following hydro-seeding, and the start of the rainy season. Walnut Creek, areas of non-wetland (uplands)will be excavated to lower elevation to where re- ablishment of perennial wetlands can occur; increasing wetland habitat in the channel. Emergent Marsh, I ponded areas in Lower Walnut Creek channel will remain intact habitat and will be protected from the avation project with 2 foot berms/buffers. project has been designed as self-mitigating. 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Ch / . . . \ -N: \ k \ 0 � . / @ 0 k ± . \ m ® ` E » \ \ ( Z $ c o \ $ 2 f 2 \ / . / / �\ . . \ - \ / � a CALIFORNIA ENVIRONMENTAL QUALITY ACT NOTICE OF DETERMINATION CONTRA COSTA COUNTY COMMUNITY DEVELOPMENT DEPARTMENT 651 PINE STREET 4TH FLOOR NORTH WING MARTINEZ, CALIFORNIA 94553-0095 Telephone: (925)313-2296 Contact Person: Cece Sellgren, Environmental Planner Project Description, Common Name (if any) and Location: Lower Walnut Creek and Lower Grayson Creek Floodplain Restoration and De-Silting Project. CP#05-30 Project #7520 6B9353.The project consists of floodplain restoration and de-silting excavation work in the floodplains of Lower Walnut Creek between Concord Blvd. and Drop Structure 1 (below Monument Blvd.), and Lower Grayson Creek from Highway 4 to Chipancingo Pkwy.). The low flow channel in both creeks will not be impacted during the excavation work, and will be protected by a two-foot berm/buffer zone that will be flagged prior to start of construction. Identified non-wetland areas in Walnut Creek, and wetland areas in Lower Grayson Creek will be excavated to restore the flood plain to design elevations. To ensure that construction/excavation activities do not impact sensitive areas in the project area,temporary flagging with tape will be installed around wetland areas, the low flow channel, and ponded areas to delineate a two foot buffer zone/berm that will isolate sensitive areas from impacts during construction in Walnut Creek. Buffer zones will be established around the low flow channel of Lower Grayson Creek. County staff will instruct the contractor on installation of the buffer zone, and will be diligent with making sure that the buffer zone is strictly respected during construction. It will be necessary to construct approximately 8 - 10 temporary access ramps from the access road at the top of the flood control channel into the Lower Walnut Creek floodplain for machinery access during construction. These temporary ramps will be made of material excavated from the non-wetland areas of the floodplain, and will be removed after the project is complete. Each ramp will require approximately 125 cubic yards of material, and will extend from the top of the trapezoidal channel into the flood plain. Avoidance and minimization measures will be incorporated into the project to ensure that environmental impacts are kept to a less than significant level. The project was approved on Pursuant to the provisions of the-California Environmental Quality Act: ❑ An Environmental Impact Report was prepared and certified (SCH# ) ❑ The Project was encompassed by an Environmental Impact Report previously prepared for (SCH# ). ® A Negative Declaration was prepared Copies of the record of project approval and the Negative Declaration or the final EIR may be examined at the office of the Contra Costa County Public Works Department. ® The Project will not have a significant environmental effect. ❑ The Project will have a significant environmental effect. ® Mitigation measures were made a condition of approval of the project. ❑ A statement of overriding considerations was adopted. ❑ Findings were adopted pursuant to Section 15091 of the State CEQA Guidelines. Date: i By: Community Development Department Representative AFFIDAVIT OF FILING AND POSTING I declare that on i I received and posted this notice as required by California Public Resources Code Section 21152(c). Said notice will remain posted for 30 days from the filing date. Signature Title Applicant: Department of Fish and Game Fees Due Public Works Department ❑ EIR;-$850 Total Due: $$1,300 255 Glacier Drive ® Neg. Dec.-$1,250 Total Paid $ Martinez, CA 94553 ❑ DeMinimis Findings-$0 Attn: ® County Clerk-$50 Receipt#: CALIFORNIA ENVIRONMENTAL QUALITY ACT NOTICE OF DETERMINATION CONTRA COSTA COUNTY COMMUNITY DEVELOPMENT DEPARTMENT 651 PINE STREET 4TH FLOOR NORTH WING MARTINEZ, CALIFORNIA 94553-0095 Telephone: (925)313-2296 Contact Person: Cece Seligren, Environmental Planner Project Description, Common Name (if any) and Location: Lower Walnut Creek and Lower Grayson Creek Floodplain Restoration and De-Silting Project. CP#05-30 Project #7520 6139353.The project consists of floodplain restoration and de-silting excavation work in the floodplains of Lower Walnut Creek between Concord Blvd, and Drop Structure 1 (below Monument Blvd.), and Lower Grayson Creek from Highway 4 to Chipancingo Pkwy.). The low flow channel in both creeks will not be impacted during the excavation work, and will be protected by a two-foot berm/buffer zone that will be flagged prior to start of construction. Identified non-wetland areas in Walnut Creek, and wetland areas in Lower Grayson Creek will be excavated to restore the flood plain to design elevations. To ensure that construction/excavation activities do not impact sensitive areas in the project area, temporary flagging with tape will be installed around wetland areas, the low flow channel, and ponded areas to delineate a two foot buffer zone/berm that will isolate:sensitive areas from impacts during construction in Walnut Creek. Buffer zones will be established around the low flow channel of Lower Grayson Creek. County staff will instruct the contractor on installation of the buffer zone, and will be diligent with making sure that the buffer zone is strictly respected during construction. It will be necessary to construct approximately 8 -10 temporary access ramps from the access road at the top of the flood control channel into the Lower Walnut Creek floodplain for machinery access during construction. These temporary ramps will be made of material excavated from the non-wetland areas of the floodplain, and will be removed after the project is complete. Each ramp will require approximately 125 cubic yards of material, and will extend from the top of the trapezoidal channel into the flood plain. Avoidance and minimization measures will be incorporated into the project to ensure that environmental impacts are kept to a less than significant level. The project was approved on Pursuant to the provisions of the-California Environmental Quality Act: ❑ An Environmental Impact Report was prepared and certified (SCH# ) ❑ The Project was encompassed by an Environmental Impact Report previously prepared for (SCH# ). ® A Negative Declaration was prepared Copies of the record of project approval and the Negative Declaration or the final EIR may be examined at the office of the Contra Costa County Public Works Department. N The Project will not have a significant environmental effect. ❑ The Project will have a significant environmental effect. N Mitigation measures were made a condition of approval of the project. ❑ A statement of overriding considerations was adopted. ❑ Findings were adopted pursuant to Section 15091 of the State CEQA Guidelines. Date: By: Community Development Department Representative I AFFIDAVIT OF FILING AND POSTING I declare that on I received and posted this notice as required by California Public Resources Code Section 21152(c). Said notice will remain posted for 30 days from the filing date. I Signature Title Applicant: Department of Fish and Game Fees Due Public Works Department E] EIRE-$850 Total Due: $$1,300 255 Glacier Drive N Neg. Dec.-$1,250 Total Paid $ Martinez, CA 94553 ❑ DeMinimis Findings-$0 Attn: ® County Clerk-$50 Receipt#: l i Public Comments j STATE OF CALIFORNIA - Governor's Office of Planning and Research State Clearinghouse and Planning Unit �apcau Arnold Sean;Walsh Schwarzenegger Director Governor April 20,2006 P� 25 � 006 Carrie DovzakcvctaIq Contra Costa County Community Development vpN1 pH v A i FRSM�IIT 651 Pine Street p�a�1p 4th Floor,North Wing Martinez,CA 94553 Subject: Lower Walnut Creek and Lower Grayson Creek Floodplain Restoration and De-Silting Project , SCH#: 2006032106 Dear Carrie Dovzak: The State Clearinghouse submitted the above named Negative Declaration to selected state agencies for review. On the enclosed Document Details Report please note that the Clearinghouse has listed the state agencies that reviewed your document. The review period closed on April 19,2006,and the comments from the responding agency(ies)is(are)enclosed. If this comment package is not in order,please notify the State Clearinghouse immediately. Please refer to the project's ten-digit State Clearinghouse number in future correspondence so that we may respond promptly. Please note that Section 21104(c)of the California Public Resources'Code states that: "A responsible or other public agency shall only make substantive comments regarding those activities involved in a project which are within an area of expertise of the agency or which are . required to be carried out or approved by the agency. Those comments shall be supported by specific documentation." These comments are forwarded for use in preparing your final environmental document. Should you need more information or clarification of the enclosed comments,we recommend that you contact the commenting agency directly. This letter acknowledges that you.have complied with the State Clearinghouse review requirements for.,draft environmental documents,pursuant to the California Environmental.Quality Act. Please contact the State Clearinghouse at(916)445-0613 if you have any questions regarding the environmental review process. Sincerely, " Terry Rob s Director,State Clearinghouse Enclosures cc: Resources Agency 1400 TENTH.STREET P.O.BOX 3044 SACRAMENTO,CALIFORNIA 95812-3044 TEL(916)445-0613 FAX(916)323-3018 www,opr.ca.gov Document Details Report State Clearinghouse Data Base SCH4 2006032106 Project Title Lower Walnut Creek and Lower Grayson Creek Floodplain Restoration and De-Silting Project Lead Agency Contra Costa County Community Development Type Nag Negative Declaration Description Project includes desilt of selected areas in Lower Walnut Creek and Lower Grayson Creek,to restore capacity in the flood control. Lead Agency Contact Name Carrie Dovzak Agency Contra Costa County Community Development_ Phone (925)313-2190 Fax email Address 651 Pine Street 4th Floor, North Wing City Martinez State CA Zip 94553 Project Location County Contra Costa City Concord, Pleasant Hill Region Cross Streets Willow Pass Road, Chipancingo Parkway Parcel No. Rancho M DD Township Range Section Base Proximity to: Highways 1-680 Airports Concord Railways Waterways Walnut Creek, Grayson Creek Schools Land Use Public Space Project Issues AestheticNisual;Air Quality;Archaeologic-Historic;Flood Plain/Flooding; Geologic/Seismic; Noise; Soil Erosion/Compaction/Grading;Toxic/Hazardous;Traffic/Circulation;Vegetation;Water Quality; Wetland/Riparian;Wildlife Reviewing Resources Agency; Regional Water Quality Control Board,Region 2;Department of Parks and Agencies Recreation;Native American Heritage Commission;Office of Historic Preservation;Department of Fish and Game, Region 3; Department of Water Resources;California Highway Patrol; Caltrans, District 4; San Francisco Bay Conservation and Development Commission; Caltrans, Division of Aeronautics; Department of Toxic Substances Control;State Water Resources Control Board, Division of Water Quality Date Received 03/21/2006 Start of Review 03/21/2006 End of Review 04/19/2006 i t Note: Blanks in data fields result from insufficient information provided by lead agency. Department of Toxic Substances Control Maureen F. Gorsen, Director Alan C.Lloyd,Ph.D. I 700 Heinz Avenue, Suite 200 Arnold Schwarzeneggi Agency Secretary Berkeley, California 94710-2721 Governor Cal/EPA April 14, 2006 IVED Ms. Carrie Dovzak APR 1 9 2006 Contra Costa County Public Works Department STATE CLEARING HOUSE 255 Glacier Drive Martinez, California 94553 Dear Ms. Dovzak: The Department of Toxic.Substances Control (DTSC) has reviewed the Initial Study (IS) of February 9, 2006 and Notice of Public Review and Intent to Adopt a Proposed Mitigated Negative Declaration (MND) of March 16, 2006 for the Lower Walnut Creek and Lower Grayson Creek Floodplain Restoration.and De-silting Project.(SCH #2006032106). As you may be aware, DTSC oversees the cleanup of hazardous substance release sites and regulates hazardous waste pursuant to the California Health and Safety Code, Division 20, Chapters 6.5 and 6.8. As a potential Responsible Agency, DTSC is submitting comments to ensure that the California Environmental Quality Act (CEQA)documentation prepared for this project adequately addresses any management of hazardous waste and remediation of hazardous substance releases that might be required as part of the project. The IS indicates on page 12'in the Hazards and Hazardous Materials section that sediments to be disturbed and/or moved in the course of work at the project site have the potential to contain hazardous materials, such as metals or hydrocarbons.. Sediments removed from the floodplain are to be stockpiled and disposed at the Tesoro Refinery if they meet the facility's criteria. More specific information needs to be provided on the approach or.procedures that will be followed in sampling, handling, and making a determination on the proper disposal of the sediments. The information that should be provided includes: 1) the contaminants potentially present in the sediments to be removed and the analyses that are to be performed for the samples.collected from the floodplain and stockpiles:at the Tesoro Refinery or how the appropriate analyses will be determined;2) the frequency and location of samples and methods for sample collection; 3) whether sediments from areas in the floodplain with relatively higher concentrations of contaminants will be segregated and handled following different procedures and with separate stockpiles; and 4) the specific criteria or types of criteria that will be used to determine the appropriate handling and disposal of the sediments. G4/rJzl/LGGO G7:LJ :71 GL OO:J:J:J7 t'ML.I lv-U VJ " - -- STATE OP C.rLLFOR*nA--HLINESR 'ro dDTSPORTATION ND HOLiaiN(''A FN[W NOLA SCHW 7FNFGGER Cmarnor DEPARTMENT OF TRANSPOUTATION 111 GRAND AVENUE P.O. BOX 23660 OA ANA CA, 94623-0660 Flex your powerl PHONE(510)286-6505 Be energy efficient/ FAX(510)286-5559 TTY(600)735-2929 RECEIVED dear y-l �•db April 5, 2006 APR 0 5 2006 STATE CLEARING HOUSE CC680552 CC-680-R18.71 SCR2O06032106 Ms. Came Dovzak Planner II Contra Costa County Public Works Department 255 Glacier Drive Martinez, CA 94553 Dear Ms.-DOVzak: Lower Walnut Creek and Lower Grayson Creek Floodplain Restoration and De- Silting Project—Intent to Adopt a Proposed Mitigated Negative Declaration Thank you for including the California Department of Transportation (Department) in the early stages of the environmental review process for the Lower Walnut Creek and Lower Grayson Creek Floodplain Restoration and De-Silting Project. We have reviewed the Intent to Adopt a Proposed Mitigated Negative Declaration and have the following comments to offer: Encroachment Permit Work that encroaches onto the State ROW requires an encroachment permit that is issued by the Department. Traffic-related mitigation measures will be incorporated into the construction plans during the encroachment permit process. See the following website link for more information: h[tp://www.dot.ca.gov/by/traff,Qps/developserv/pemnits/ To apply for an encroachment permit, submit a completed encroachment permit application, environmental documentation, and five (5) sets of plans (in metric units) which clearly indicate State Right of Way to: i 'Caltrana improves mobility across California' d4/d�/lddb d�:1� b1018b5b5y GHLIkHNs rauc rc Ms.Carrie Aonak April 5,2006 Page 2 Depaztment of Transportation i Office of Permits Attn: Sean Nozzari I I I Grand Avenue, 6`b Floor Oakland,CA 94612 Should you require further information or have any questions regarding this letter, please call Christian Bushong of my staff at (510)286,5606. Sincerely, TIMOTHX . SABLE District Br ch Chief IGWCEQA c: State Clearinghouse i `Cdltrans irnprooes mobility across CatifOMW STATE OF CALIFORNIA—BUSINESS TRANSPORTATION AND HOUSING AGENCY ARNOLD SCHWARZENEGGER.Govemor DEPARTMENT OF TRANSPORTATION DIVISION OF AERONAUTICS—M.S.#40 ' 1120 N STREET P.O.BOX 942873 Flex your power! SACRAMENTO,CA 94273-0001 Be energy efficient! PHONE (916) 654-4959 FAX (916)653-9531 TTY(916)651-6827 April 19, 2006 Ms. Carrie Dovzak Contra Costa County Community Development Department 651 Pine Street Martinez, CA 94553 Dear Ms. Dovzak: Re: Contra Costa's Negative Declaration for the Lower Walnut Creek and Lower Grayson Creek Floodplain Restoration and De-Silting Project; SCH# 2006032106 The California Department of Transportation (Caltrans), Division of Aeronautics (Division), reviewed the above-referenced document with respect to airport-related noise and safety impacts and regional aviation land use planning issues pursuant to the California Environmental Quality Act (CEQA). The Division of Aeronautics has technical expertise in the areas of airport operations safety and airport land use compatibility. We are a funding agency for airport projects and we have permit authority for public use airports and heliports. We offer the following comments for your consideration. The proposal consists of floodplain restoration and de-silting excavation work in the floodplains of Lower Walnut Creek between Concord Boulevard and Drop Structure 1 L(below Monument Boulevard), and Lower Grayson Creek from Highway 4 to Chipancingo Parkway. The project site is located in the vicinity Buchanan Field Airport. The proposal includes plans for the "re-establishment of perennial wetlands" on approximately seven acres. Land use practices that attract or sustain hazardous wildlife populations on or near airports can significantly increase the potential for wildlife-aircraft collisions. The Federal Aviation Administration (FAA)recommends that wetlands and other uses that have the potential to attract wildlife be restricted in the vicinity of an airport. FAA Advisory Circular(AC) 150/5200-33A entitled "Hazardous Wildlife Attractants on or Near Airports" at http://faa. ov/airports_airtraffic/airports/- resources/advisory circulars/media/150-5200-33A/150_5200 33a.pdf addresses these.issues. For additional information concerning wildlife damage management, you may wish to contact the United States Department of Agriculture, Wildlife Services, at (916) 979-2675. The proposal should be submitted to the Contra Costa County Airport Land Use Commission (ALUC) for review. The applicant should coordinate closely with airport staff to monitor wildlife activity and to ensure compatibility with future'as well as existing airport operations. The protection of airports from incompatible land use encroachment is vital to California's economic future. Buchanan Field Airport is an economic asset that should be protected through effective airport land use compatibility planning and awareness. Although the need for compatible and safe land uses near airports in California is both a local and a state issue, airport staff, airport land use commissions and airport land use compatibility plans are key to protecting an airport and the people residing and "Caltrans improves mobility across California" Ms. Carne Dovzak April 20, 2006 Page 2 working in the vicinity of an airport- Consideration given to the issue of compatible land uses in the vicinity of an airport should help to relieve future conflicts between airports and their neighbors. These comments reflect the areas of concern to the Caltrans Division of Aeronautics with respect to airport-related noise and safety impacts and regional airport land use planning issues. We advise you to contact our District 4 Office in Oakland at (510) 286-4444 concerning surface transportation issues. Thank you for the opportunity to review and comment on this proposal. If you have any questions, please call me at (916) 654-5314. Sincerely, =YSINARD Aviation Environmental Planner c: State Clearinghouse, Buchanan Field Airport, Contra Costa County ALUC i i Caltrans improves mobility across California' i EAST BAY MUNICIPAL UTILITY DISTRICT April 10, 2006 Carrie Dovzak, Planner II Contra Costa County Public Works Department 255 Glacier Drive Martinez, CA 94553 Re: Proposed Mitigated Negative Declaration—Lower Walnut Creek and Lower Grayson Creek Floodplain Restoration and De-silting Project, Contra Costa County Dear Ms. Dovzak: East Bay Municipal Utility District(EBMUD) appreciates the opportunity to comment on the Mitigated Negative Declaration for the Lower Walnut Creek and Lower Grayson Creek Floodplain Restoration and De-silting Project located in Contra Costa County. The project is located outside of EBMUD's Ultimate Service Boundary and does not affect any EBMUD facility; therefore, EBMUD has no comments regarding environmental issues for this project. If you have any questions concerning this response, please contact David J. Rehnstrom, Senior Civil Engineer, Water Service Planning at(510)287-1365. Sincerely, i irk atric P anager of Water Distribution Planning WRK:NJR:sb sb06 102,doc I i i i I f 375 ELEVENTH STREET. OAKLAND. CA 94607-4240. TOLL FREE 1-866-40-E13MUD flarycle0 Papei 04/21/06 16:40 PAX 9256713381 ConcordPermitCenter doo1 r i I C®rlcmr-. City of Concord Department of Economic Development&Planning Planning Division 1950 Parkside Drive, MS/53 Concord, California 94519 Phillip Woods 925/671-3284 Fax: 925/671-3381 Date: April 21, 2006 TO: Ms. Carrie Dovzak Planner U Contra Costa County Public Works Department 255 Glacier Drive Martinez, CA 94553-4897 )Fax no.: (925)313-2333 Subject:City of Concord's Comments on the Mitigated Negative Declaration for the Lower Walnut Creek and Grayson Creek Floodplain Restoration and De-Silting Project(County File No. CP 05-30) 5 pages including this page. Please find attached the City of Concord's Comments on the Mitigated Negative Declaration for the Lower Walnut Creek and Grayson Creek Floodplain Restoration and De-Silting Project w6o�k i Phillip Woods 1 a 04/21/06 16:40 FAX 9256713381 ConcordPermitCenter Q002 1 TRANSMITTAL Cone d� City of Concord Department of Economic Development &Planning Planning Division 1950 Parkside Drive,MS/53 Concord, California 94519 Phillip Woods 925/671-3284 Fax: 925/671-3381 Date: April 21, 2006 To: Carl Roner Contra Costa County Public Works Department 255 Glacier Drive Martinez, CA 94553-4897 Fax no.: (925)313-2333 Subject:City of Concord's Comments on the Mitigated Negative Declaration for the Lower Walnut Creek and Grayson Creek Floodplain Restoration and De-Silting Project(County File No. CP 05-30) 5 pages including this page. Please find attached the City of Concord's Comments on the Mitigated Negative Declaration for the Lower Walnut Creek and Grayson Creek FIoodplain Restoration and De-Silting Project O Phillip Woods i 04/21/06 16:40 FAX 9256713381 CoucordPermitCenter U003 CrrY or CONCORD Cm COUNCIL I'Mor CsN•rra Susan A.Bonilla,Mayor 1950 Parkside Drive i Mark A.Peterson,Vice Mayor Concord,California 94519-2578 + Helen M.Allen Laura M.Hoffineister Telephone: (925) 671-3454 _ William D.Shinn Fat (925) 671-3381 _ Mary Rae Lehman,City Clerk Thomas Wending,Ciry Treasurer i Lydia E.Du Borg,Cicy Manager April 21, 2006 VIA FAX: (925) 313-2333 (Hard copy via regular mail) Ms. Carrie Dovzak Planner II Contra Costa County Public Works Department 255 Glacier Drive Martinez, CA 94553-4897 RE: City of Concord's Comments on the Mitigated Negative Declaration for the Louver Walnut Creek and Grayson Creek Floodplain Restoration and De-Silting Project (County File No. CP 05-30) Dear Ms. Dovzak: The City of Concord has received the Notice of Public Review and Intent to Adopt a Proposed Mitigated Negative Declaration and the accompanying Initial Study for the Lower Walnut Creek and Grayson Creek Floodplain Restoration and De-Silting Project. The project consists of floodplain restoration and de-silting excavation work in the floodplain of Lower Walnut Creek between Concord Boulevard and Drop Structure No. I (below Monument Boulevard) and Lower Grayson Creek from Highway 4 to Chipancingo Parkway. It is our understanding that Contra Costa County is soliciting comments from the City of Concord to determine the adequacy of the environmental document. The City has contacted and requested additional information from the Contra Costa County Public Works Department to allow the City to complete its assessment of the Initial Study. A meeting has been scheduled for Monday, April 24, 2006 with staff from both the City of Concord and Contra Costa County to go over the information requested and the items presented in this letter. The City would request that the Public Comment Period for the Initial Study be extended to allow time for the City's review of new information that is received from this meeting. Based on the information received so far, the City has evaluated the Initial Study and is providing written comments that outline issues and concerns that significantly demonstrate adverse impacts to the City of Concord. The comments provided in this letter are to indicate the i I I e-m il: cityinfo®ci.concord.ca-us - wehsite:tawsucityofconcord.org 64/21/06 16:40 FAX 9256713381 ConcordPerwitCenter U004 Ms. Came Dovzak April 21,2006 Page 2 of 4 issues and concerns that would need to be addressed with adequate mitigation measures in the final application. Initial Study C The Initial Study states in the Recreation section that the project will have "... no effect on existing neighborhood parks in the area, but will temporarily affect the recreational use of the regional trail ..." This section should identify the traffic impacts and panting effects on Waterworld. The project description in the April 3,2006 letter from Neil Leary, Senior Civil Engineer with Contra Costa County Public Works Department, to Nohemi Navarro, Permit Center Technician III with the City of Concord, differs significantly with the Initial Study on the number of estimated truck haul trips. Mr. Leary's letter says the project "will generate approximately 3,700 to 5,600 loaded 40-ton California —legal truck trips ..." This averages to about 100 loaded haul trips per day. However, the Initial Study states "Based on the relatively small number of truck trips generated (approximately 50 per day) and the limited number of days over which the trips will occur, the impact due to the transportation of fill to the nearby Tesoro Refinery is less than significant." This varies significantly from the information provided in the Initial Study. Whether it is 50 or 100 loaded haul trips per day, the weight of the loaded trucks poses a potentially significant maintenance problem for City maintained streets, parking lots, curbs, and sidewalks. The weight of the trucks could cause structural damage to streets and the Waterworld parking lot. Trucks driving over the curb and sidewalk could cause them to chip, crack, and/or break. Mitigation Measures need to be identified to mitigate the potential damage to-City property. The Mitigated Negative Declaration states that "Flaggers will be used at complicated intersections when necessary ..." Mitigation Measure need to include provisions for flaggers to be available for tricks exiting into the roadway at all times. All flagging operations on City streets and the Waterworld parking lot must use certified flaggers. Items Needing Additional Clarification c Indicate the location of where the ofthaul material is being hauled. c Indicate whether or not all.areas shown on the plan will be worked on simultaneously or will worked from north to south. o Indicate whether CCCFC prepared a public notice to business in the area that will be affected by this construction. Items that Require Mitigation Measures o The City has two sewer mains (30" and 18") crossing the Walnut Creek Channel. They are in the area delineated as N and M on the plans. Extreme caution is required in this i 04/21/06 16:40 FAX 9256713381 Concor. dPermitCenter U004 Ms. Came Dovzak April 21,2006 Page 2 of 4 I issues and concerns that would need to be addressed with adequate mitigation measures in the final application. Initial Study • The Initial Study states in the Recreation section that the project will have "... no effect on existing neighborhood parks in the area, but will temporarily affect the recreational use of the regional trail ..." This section should identify the traffic impacts and parking effects on Waterworld. • The project description in the April 3, 2006 letter from Neil Leary, Senior Civil Engineer with Contra Costa County Public Works Department, to Nohemi Navarro, Permit Center Technician III with the City of Concord, differs significantly with the Initial Study on the number of estimated truck haul trips. Mr. Leary's letter says the project "will generate approximately 3,700 to 5,600 loaded 40-ton California —legal truck trips ..." This averages to about 100 loaded haul trips per day. However, the Initial Study states `Based on the relatively small number of truck trips generated (approximately 50 per day) and the limited number of days over which the trips will occur, the impact due to the transportation of fill to the nearby Tesoro Refinery is less than significant." This varies significantly from the information provided in the Initial Study. • Whether it is 50 or 100 loaded haul trips per day, the weight of the loaded trucks poses a potentially significant maintenance problem for City maintained streets, parking lots, curbs, and sidewalks. The weight of the trucks could cause structural damage to streets and the Waterworld parking lot. Trucks driving over the curb and sidewalk could cause them to chip, crack, and/or break. Mitigation Measures need to be identified to mitigate the potential damage to-City property. • The Mitigated Negative Declaration states that "Flaggers win be used at complicated intersections when necessary ..." Mitigation Measure need to include provisions for flaggers to be available for trucks exiting into the roadway at all times. All flagging operations on City streets and the Waterworld parking lot must use certified flaggers. Items Needing Additional Clarification o Indicate the location of where the offhaul material is being hauled. e Indicate whether or not all.areas shown on the plan will be worked on simultaneously or will worked from north to south. a Indicate whether CCCFC prepared a public notice to business in the area that will be affected by this construction. Items that Require Mitigation Measures o The City has two sewer mains (30" and 18") crossing the Walnut Creek Channel_ They are in the area delineated as N and M on the plans. Extreme caution is required in this i 04/21/06 16:41 FAX 9256713381 ConcordPermitCenter [7J 005 Ms. Came Dovzak April 21, 2006 Page 3 of j area. Concord Public,Works would like to see the cross section of this area for the depth of the proposed de-silting. Provide a description of operation schedule that includes time and days of week. The hours can not conflict with peak hour traffic on Concord Avenue, Meridian Park Boulevard, Diamond Boulevard, Waterworld Parkway, Willow Pass Road, and other nearby streets. Indicate location of truck staging. Please note, the City will not allow the trucks to be lined up along sides of the roadways, especially along Waterworld Pkwy. a During operation of Waterworld Park, the parking attendants collect parking fees approximately 200 feet .from Enea Circle. This causes traffic to back up along Waterworld Pkwy. A flagger will be needed in this area to guide the trucks against traffic. Contra Costa County needs to work directly with Waterworld Park. o The project description indicates construction vehicles are proposing to travel on Waterworld Parkway and through the Waterworld parking lot during its operation. During peak operation this can be a heavily congested corridor with pedestrians, bicyclists, buses, cars, and other vehicles going to and from Waterworld. A measure needs to be identified to ensure the safety of people and vehicles on the nearby streets and parking lot of the Waterworld complex. o The road way to the pump station (at the end of Waterworld Pkwy R.O.W.) will not take this type of truck weight. At the very least 1,500 linear feet of the pavement will be severely damaged by the truck traffic. This will need to be repaved. All other damages to roads and infrastructure shall be restored. o The contractor needs to advance a deposit against damages. u Pictures or video of roads and structures to be used need to be provided before work starts. This should be done in conjunction with Current Development and Public Works. During the encroachment permit application process, Contra Costa County has stated that all trucks will be "legal load." Given that the off haul will be wet materials, the City will require and conduct spot checks on the truck weights. o Once the District issue's the contract the City would like to see the contractor's location of the service area for the�equipment performing the excavation. The trucks could potentially spill their haul load onto City streets and other property. The spill could ultimately go down the storm water drains, which would negate some of the r t V4it1i(JO 10:41 ree yGab/10081 uoncoraYermitcenter 16 006 Ms. Carrie Dovzak April 21, 2006 Page 4 of 4 i benefits of the proposed project. The truck beds shall be lined and covered when traversing City streets and the Water-world parking lot. m The City will require a street sweeper to be on and used stand-by as needed. o The traffic division has a bone pile ofpoles on the point at the pump station that will need coordinated to be moved. Thank you for the opportunity to review and comment on the Lower Walnut Creek and Grayson Creek.Floodplain Restoration and De-Silting Project. The environmental document needs to address the concems and significant impacts that the City of Concord has identified in this letter. The City will be providing additional comments after our scheduled meeting on Monday, April 24, 2006. If you have any questions regarding these comments, or would like to discuss them further,please contact me at(925) 671-3284. Ve Iy yours, Phillip Woods,AICP Principal Planner cc: Carl Rohner, Contra Costa Public Works Alex Pascual, City Engineer and Director of Building, Engineering, and Neighborhood Services Qamar Khan, Director of Public Works—Maintenance Services John Templeton, Transportation Manager Abu]Hossain, Transportation Program Manager Mario Cainorongan, Senior Civil Engineer Libbey Bell,Public Works Engineer III Shea Halligan; Senior Construction Inspector Nohemi Navarro, Permit Technician III i 061tr.059 i I EAST BAY REGIONAL PARK DISTRICT E e V E D BOARD OF DIRECT Carol Severin APR 242006 Wad 3ent CONTRA COSTA COUNTY John Sutter April 19, 2006 PUBLIC WORKS DEPARTMENT Vice-President Ward 2 Carrie Dovzak Ayn Wieskamp Planner 11 treasurer Contra Costa County Public Works Dept. Ward 5 255 Glacier Drive Ted Radke Martinez, Ca 94553 secretary Ward 7 Subject: LOWER WALNUT CREEK& LOWER GRAYSON CREEK Beverly Lane � Ward 6 FLOODPLAIN RESTORATION&DESILTING PROJECT FILE NO: CP#: 05-30 Doug Sitlen Ward 4 Dear Ms. Dovzak: Nancy Skinner Ward 1 The East Bay Regional Parks District(the `District')has received and reviewed the Mitigated Pat O'Brien Negative Declaration (MND) for the Lower Walnut Creek and Lower Grayson Creek General Manager . Floodplain Restoration and Desilting Project. The District maintains and operates the Iron Horse Regional Trail, a recreational trail, on the westerly paved access road adjacent to the Walnut Creek Channel between Concord Avenue and Diamond Boulevard in the City of Concord. The Contra Costa County Flood Control District (CCCFCD) operates a parallel unpaved access road located along the easterly portion of the Walnut Creek Channel between Concord Avenue and Diamond Boulevard. The Environmental Checklist Form included in the Notice of Public Review and Intent to Adopt a Proposed Mitigation Negative Declaration sent to the District dated March 16, 2006 was missing all even numbered pages and therefore significant portions of the environmental analysis was not provided to the District. Our comments below are based on the pages received. However, the District requests that a complete copy of the environmental checklist be provided and that additional comments accepted based on our review of the full document once received. Pursuant to the California Environmental Quality Act (CEQA), a project would have a significant impact if it is determined that the project would increase use of recreational facilities such that substantial physical deterioration of the facility would occur or be accelerated. The proposed project intends to dramatically increase the use of this pedestrian trail by utilizing it as a staging area and a route for ingress and egress for various pieces of construction equipment and dump trucks for approximately 40 working days. The increase of use of the trail by these pieces of equipment would have the potential to result in or accelerate the physical deterioration of.the pavement on the trail, thus resulting in a significant impact pursuant to CEQA. Additionally, the project will require the removal of District fencing established along the creek bank for the purpose of public safety. I 2950 Peralta Oaks Court P.O.Box 5381 Oakland,CA 94605-0381 TEL 510 635-0135 rAw 510 569-4319 too 510 633-0460 www.ebparks.org The proposed project should be required to incorporate mitigation measures in the MND to address the likely significant impacts associated with increased use of the paved trail and removal of safety fencing and potential damage to other facilities. The District requests that the following mitigation measure be incorporated into the project: . Mitigation Recreation - 1: The CCCFCD must exercise reasonable care by utilizing the unpaved access road on the easterly banks of Walnut Creek during all project phases between Concord Avenue and Diamond Boulevard. If it is determined the use of the unpaved access road is not feasible, the CCCFCD must cooperate with the District to ensure that any physical damage to the paved recreational trail, safetyfencing, and/or other facilities is repaired to the satisfaction of the District, or the District is adequately reimbursed for any repair costs incurred as a result of the proposed project. The Iron Horse Trail would be closed for a minimum of 40 working days (Aug. I to Oct. 1) due to the proposed project. Unfortunately, as mentioned above, the .District has only . received odd numbered pages, which did not include the Transportation and Circulation analysis. The Iron Horse Trail is a substantial commuter route for bicycles and pedestrians in the Central Contra Costa County region. The proposed project must adequately address the closure of this pedestrian route, and mitigation measures should be incorporated to require the CCCFCD to provide public information and signage regarding the trail closure and alternate routes. Without the analysis of the issues discussed above, and the provision of mitigation measures to adequately mitigate significant impacts to the physical deterioration and closure of recreational and commuter facilities, a fair argument could be made pursuant to CEQA that the proposed project requires a^full Environmental Impact Report. The District requests that the MND be revised and recirculated to include measures that will adequately address all of the likely significant impacts associated with the Lower Walnut Creek and Lower Grayson Creek Floodplain Restoration and Desilting Project Thank you for the opportunity to review and comment on this project. We would appreciate receiving future information about this project, including the required revised environmental analysis, as it becomes available. Please feel free to contact me at (510) 544-2607, or by email at nwennin er ,ebparks.org, should you have any questions. Respectfully, i Nancy Wenni ger Land Acquisit on Manager Cc: Mitch Avalon,Deputy Director—Contra Costa Co.Public Works. Neil Leary, Senior Civil Engineer—Contra Costa Co.Public Works Robert Doyle,Assistant General Manager-EBRPD t i i i Response to Public Comments i i t FLOOD Contra Costa County Maurice M.Shiu g t FLCONTROL LJ ex officio Chief Engineer 255 Glacier Drive, Martinez, CA 94553-4i: & Water Conservation District Telephone: (925) 313-2000 FAX (925)313-2333 f April 26, 2006 Nancy Wenninger East Bay Regional Park District 2950 Peralta Oaks Court Oakland, CA 94605-0381 Attn. Brian Holt Our File: Lower Walnut Creek/Lower Grayson Creek De-silting And Flood Plain Restoration Project Project Number: 7520 689353 Dear Ms. Wenninger. Thank you for your comments regarding the Lower Walnut Creek/Lower Grayson Creek De-silting and Flood Plain Restoration Project. We acknowledge your comments of concern regarding cooperation between the Park District and Contra Costa County on various aspects of the project scope that may affect the Iron Horse Trail, which is located along the west bank of the Lower Walnut Creek Channel, in the area being desilted this summer. As you have heard from Paul Detjens we have shifted the location of the upland areas to be desilted from the west side to the east side of Walnut Creek Channel, in the vicinity of Waterworld Parkway.This approach restricts our impacts to only the east side of the floodplain bench and avoids the impacts of crossing the active stream channel. It also means that this summer's work will not require a trail closure, nor will our contractor need to use the District's access roads where the Iron Horse Trail has been constructed. Because of this shift in the work area,we anticipate that our next desilt project will need to focus on the western floodplain bench and this future desilt project will require a temporary trail closure. While we have not yet scheduled this project,we will be sure to coordinate with the Park District at that time concerning the Iron Horse Trail. Thank you for your comments. If you have any questions about the project or this letter, please call me at (925)313-2190 or e-mail me at cdovz@pw.cccounty.us. Thank you. Sincerely, Carrie Dovzak ! Planner 11 Environmental Services I CD:cd G:\GrpData\EngSvc\ENVIRO\Flood Contrdl\LowerwC_GRAYDesilt\CEQA\Public_comments\EBRPD_Itr.doc cc: P.Detiens—Flood Control L.Chavez-Environmental i f P � h Contra Costa County Maurice M. Shiu \ FLOOD CONTROL ex officio Chief Engineer 255 Glacier Drive, Martinez, CA 94553-4& & Water Conservation District Telephone: (925) 313-2000 FAX (925) 313.2333 April 26, 2006 Sandy Hesnard Department of Transportation Division of Aeronautics 1120 N Street Sacramento, CA 94273-0001 Our File: Lower Walnut Creek/ Lower Grayson Creek De-silting And Flood Plain Restoration Project Project Number: 7520 669353 Dear Ms. Hesnard: Thank you for your comments regarding the Lower Walnut Creek/ Lower Grayson Creek De-silting and Flood Plain Restoration Project. We acknowledge your comments of concern regarding the potential for "re-establishment of perennial wetlands" in the Walnut Creek Channel in the vicinity of the Contra Costa County's Buchanan airport. Buchanan Airport staff are employees of Contra Costa County Public Works, and have been notified of the plans to de-silt south of the airport. The current project area is located south of Concord Avenue, and extends, in selected identified areas to Drop #1, south of Willow Pass Road. The areas selected for de-silting are not adjacent to the airport, nor are they clustered in one large area, rather they are spaced intermittently along the full project limits. In fact, the airport was taken into consideration when the project was first defined, and reaches directly adjacent to the airport were not included in the final plan. Pods of areas to be desilted are interspersed with other existing wetland areas along the creek, and are not expected to substantially increase wildlife use beyond exisiting use. Landuse surrounding the reaches to be de-silted are predominantly highly urbanized commercial businesses, and not conducive to attracting large numbers of wildlife. This reach of Walnut Creek (including the reach immediately adjacent to the airport) have been previously de-silted, and there were no reports of increases in hazardous wildlife populations in the area after these projects were completed. i i Airport staff will be notified when desilting activities will occur. Thank you for your comments. If you have any questions about the project or this letter, please call me at (925) 313-2190 or e-mail me at cdovz@pw.cccounty.us. Thank you. Sincerely, Carrie Dovzak Planner II Environmental Services CD:cd G:\GrpData\EngSvc\ENVIRO\Flood Control\LowerWC_GRAYDesilt\CEQA\Public comments\DOT_Itr.doc cc: P.Detjens—Flood Control L.Chavez-Environmental l .I i j I 2 Contra Costa County Maurice M.Shiu IFLOOD CONTROL ROL ex officio Chief Engineer t i 255 Glacier Drive, Martinez, CA 94553-48: �• & Water Conservation District Telephone: (925) 313-2000 FAX (925) 313-2333 April 24, 2006 Mr. Mark Piros, Unit Chief Northern CA— Coastal Cleanup Operations Branch Dept. of Toxic Substances Control 700 Heinz Avenue Berkeley, CA 94710-2721 Our File: Lower Walnut Creek/ Lower Grayson Creek De-silting And Flood Plain Restoration Project Project Number: 7520 6B9353 Dear Mr. Piros: Thank you for your comments regarding the Lower Walnut Creek/ Lower Grayson Creek De-silting and Flood Plain Restoration Project. Your comments concerning the potential for encountering hazardous materials in the soil during project excavation work are well taken, and have been addressed in subsequent soil sampling performed in both the Walnut Creek and Grayson Creek channels. Soil samples were taken from a total of eight representative sampling locations chosen by myself and the consultant, Ninyo and Moore, to best represent the areas that we will be excavating. Samples were tested for CAM-17 metals (EPA6010B), Total Petroleum Hydrocarbons (EPA80158), and BTEX (EPA8021 B). They were collected from depths ranging from 0.5 to 3.0 feet below ground surface following standard procedures for soil sampling, following instructions from the laboratory. None of the samples tested at Advanced Technology Laboatories (Signal Hill, CA) exceeded the Environmental Screening Levels (ESLs) from the San Francisco Bay Regional,Water Quality Board for either residential or commercial use scenarios for disposal. Nor did they exceed the human health risk ESLs. Based on this information, the consultant concluded that the creek sediments sampled do not contain constituents that would require further remedial action. Since the samples did not exceed any regulatory limits, we will not be segregating the excavated soil for individual stockpiles at the disposal site. i I The Lower Walnut Creek channel has a watershed of 93,500 acres, and is the largest watershed in Contra Costa County. The Lower Grayson Creek channel drains 11,000 acres of predominantly single family residential areas. We are unaware of any specific areas of concern along the channels and we do not anticipate concentrations of hazardous materials to be encountered in any particular area. Construction BMPs and health and.safety regulations require that work will stop in an area where obvious hazardous substances are encountered, and these practices will be followed. De-silting operations in the past did not encounter problem areas, and we do not anticipate these problems occurring during this operation. Construction and erosion control BMPs will also be implemented for handling and transport of the sediment to local disposal sites. If you have any questions about the project or this letter, please call me at(925) 313-2190 or e-mail me at cdovz@pw.cccounty.us. Thank you. Sincerely, Carrie Dovzak Planner 11 Environmental Services I i CD:cd G:\GrpData\EngSvc\ENVIRO\Flood Control\LowerWC_GRAYDesilt\CEQA\Public_comments\TSC_Itr.doc cc: P.Detjens—Flood Control L.Chavez-Environmental I i �+ Contra Costa C�o7urnnt7yrg g Maurice M.shiu t d'LOOCO H ROL ex officio Chief Engineer 255 Glacier Drive, Martinez, CA 94553-48: ;r & Water Conservation District Telephone: (925) 313-2000 FAX (925) 313-2333 April 26, 2006 Timothy C. Sable Department of Transportation 111 Grand Avenue Oakland, CA 94623-0660 Our File: Lower Walnut Creek/ Lower Grayson Creek De-silting And Flood Plain Restoration Project Project Number: 7520 6139353 Dear Mr. Sable: Thank you for your comments regarding the Lower Walnut Creek/ Lower Grayson Creek De-silting and Flood Plain Restoration Project regarding encroachment permits. Contra County Public Works staff are currently negotiating encroachment permits for our work on Grayson Creek with your staff. Thank you for your comments. If you have any questions about the project or this letter, please call me at (925) 313-2190 or e-mail me at cdovz@pw.cccounty.us. Thank you. Sincerely, Carrie Dovzak j Planner II Environmental Services CD:cd G:\GrpData\EngSvc\ENVIRO\Flood ControllLowerWC_GRAYDesilt\CEQA\Public comments\DOT2—Itr.doc cc: P.Detjens—Flood Control 1 L.Chavez-Environmental i i t i f � Z .� A cq Contra Costa County Maurice M. Shiu t ex officio Chief Engineer �`�®ji ®���,c�{}y� 255 Glacier Drive, Martinez, CA 94553-482E & Water Conservation District Telephone: (925) 313-2000 FAX (925) 313-2333 April 27, 2006 Philip Woods, Principal Planner City of Concord - Planning Division 1950 Parkside Drive, MS/53 Concord, CA 94519 Our File: Lower Walnut Creek/ Lower Grayson Creek De-silting And Flood Plain Restoration Project Project Number: 7520 6139353, 7520 6139355 Dear Mr. Woods: Thank you for your comments, and meeting with Public Works and Flood Control District staff last Monday regarding the Lower Walnut Creek/ Lower Grayson Creek De-silting and Flood Plain Restoration Project. We believe the meeting was beneficial, and I hope this letter of response will address the concerns expressed by your Division pertaining to our project. The project is the District's main priority for this summer to ensure these important facilities are ready to handle next winter's storms. The following points were discussed at the meeting, and noted in your correspondence to myself and Carl Roner (Engineer, Design group): Initial Study— Traffic impacts and parking effects on Waterworld The District has agreed to require the Contractor to excavate the northern-most and southern- most areas channel area before starting excavation directly adjacent to Waterworld. This will allow trucking operations to occur without interfering with automobile traffic from Waterworld. Work in the channel adjacent to Waterworld is expected to begin at approximately the same time that Waterworld closes weekday operations for the season —August 28th, and continue weekdays through September. Flaggers should.not be necessary at this intersection if the schedule is secure, but will be required if deemed necessary by the Resident Engineer(RE) if our haul operations are ongoing during the time Waterworld is open to the public. Truck haul trips Truck haul trips are estimated to be approximately 66 trips per day, with each truck hauling approximately 15 cubic yards of material per truckload. Photos of the street hardscape at entrances and exits to the project will be taken by District staff to document the condition at 1 t these facilities prior to start of work. The District will require that the contractor repair any damage to the frontage improvements and pavement in the immediate vicinity of the channel access points to an equal to better condition than existed prior to this project. The County will ensure successful completion of these repairs; if necessary, through retention of monies owed the Contractor, as well as obtaining a performance bond guaranteeing the work. Trucks will be legal load, and should not significantly impact Concord streets relative to the usual commercial and industrial traffic that occur in this area. Items needing clarification Offhaul material location will be determined by the contractor. A disposal site in Martinez has been identified for approximately 20,000 cubic yards, but disposal of the material is at the Contractor's discretion. Order of work is discussed above under the Traffic impacts and parking effects on Waterworld section. The contractor will complete work at the northern-most and southern-most areas before beginning the excavation adjacent to Waterworld. As per CEQA guidelines, businesses adjacent to the channel were sent a copy of our Notice of Intent/Notice of Public Review on March 21, 2006. Items that require Mitigation Measures Sewer Mains— Public Works will illustrate the location of the two Concord sewer mains on the project plans, and will require the Contractor to minimize truck traffic over the sewer lines by avoiding excavating th area over the sewer until the entire area north of the lines have been excavated to final grade, avoiding excessive vibration in the area of the mains. In addition, we will specify that a 5 foot layer of sediment be left on top of the mains until excavation in the surrounding area is completed. At no time will less than 2 feet of cover be provided over the top of the sewers. Operation Schedule-Working hours are scheduled to be Monday to Friday 7 a.m. to 6 p.m. Changes to the schedule, including Saturday schedules, must be agreed to by the onsite RE before implemention. Staging- Staging areas will be located on District Right-of-Way, which includes the District maintenance road on the east side of the channel. Trucks will not line up on City streets. Traffic and Flagger issues at Waterworld, and other entrances- The project area has changed slightly, and will not include excavation on the west side of the Walnut Creek channel. This eliminates some of the entrance;and exit, and traffic concerns that you expressed regarding traffic on Meridian Parkway in your correspondence. Access roadways at Diamond Lane and Via de Mercados have traffic signals where trucks enter onto busier roadways eliminating the need for flaggers at these intersection's. The areas to be excavated adjacent to Waterworld will be accessed through the District's driveway off of Waterworld Parkway, south of the Waterworld entrance gate, and will not impact the roadway to the City's pump station, and will not access the Waterworld parking lot. Similarly, the northern-most area will be accessed through District right- of-way via Via Mercados. Direct,access from the channel to Concord Avenue will not be allowed. Damages to roads and structures—These issues are addressed above under Truck haul trips. i 2 The County's contractor will not be required to advance a deposit against damages as agreed in the meeting on Monday. Potential for trucks to spill their haul load onto City streets - Many of your concerns expressed in our meeting concerning spillage and tracking of sediment (which has the most potential to occur during transport)will be adequately addressed in the Contractor's Stormwater Pollution Prevention Plan (SWPPP) that is'required for this project (under the County's NPDES permit). The SWPPP document will be reviewed by staff in the environmental group at CCC Public Works, and the RE assigned to the project has the responsibility of making sure the SWPPP is adhered to. The SWPPP includes construction and erosion control Best Management Practices (BMP's) that the contractor must implement before, during and after the project. We do not anticipate that the excavated sediment will be saturated; therefore, in our meeting we agreed that trucks will not require liners when carrying their loads. Bone pile location—Construction will not access the area near the City's pump station. We hope that this letter addresses all of your concerns. Please feel free to contact our offices with any concerns that occur during construction. Per our meeting on April 24, 2006 our two agencies were in agreement that project concerns had been addressed; therefore we have not extended the public review period for the CEQA document. If you have any questions about the project or this letter, please call me at(925)313-2190 or e-mail me at cdovz@pw.cccounty.us. Thank you. Sincerely, Carrie Dovzak Planner II - Environmental Services i I t f CD:cd G:\GrpData\EngSvc\ENVIRO\Flood Control\LowerWC_GRAYDesilt\CEQA\Public_comments\Concord_Itr.doc cc: P.Detlens-Flood Control L.Chavez-Environmental N.Leary—Design H.Ballenger-Admin i l 3 PROOF OF PUBLICATION (2015.5 C.C.P.) STATE OF CALIFORNIA County of Contra Costa I am a citizen of the United States and a resident of the County aforesaid; I am over the age of eighteen years, and not a party to or interested in the above-entitled matter. I am the Principal Legal Clerk of the Contra Costa Times, a newspaper of general circulation, printed and published at 2640 Shadelands Drive in the City of Walnut Creek, County of Contra Costa, 94598. And which newspaper has been adjudged a newspaper of general circulation by the Superior Court of the County of Contra Costa, State of California, under the date of October 22, 1934. Case Number 19764. The notice, of which the annexed is a printed copy (set in type not smaller than nonpareil), has been published in each regular and entire issue of said newspaper and not in any supplement thereof on the following dates, to-wit: May 22, all in the year of 2006 1 certify (or declare) under penalty of perjury that the foregoing is true algid correct. Execute at Walnut Creek, California. On thi 4 day f May, 2006 ............................................................. .... Signature Contra Costa Times P O Box 4147 Walnut Creek, CA 94596 (925) 935-2525 Proof of Publication of: (attached is a copy of the legal advertisement that published) i i Contra Costa County Flood Control and Water Conservation District 255 Glacier Drive,Marti- nez,California 94553-4897 NOTICE TO CONTRACTORS The Chief Engineer will receive sealed bids at the Public Works Depart- ment, C.C. Rich Building, 255 Glacier Drive, Marti- nez,California 94553-4897, until 2 o'clock p.m., on June 6, 2006, at which time they will be publicly opened and read, for: 2006 WALNUT CREEK CHANNEL DESILT. General work descrin- tion:Remove up to 38,0u0 cubic yards of channel excavation (Base Bid Project Plus Alternatives) from designated areas of Walnut Creek Channel be- tween Concord Avenue and Drop Structure Num- ber 1 (downstream State Route 242)in the Concord area. Engineer's cost estimate: Base Bid Project$440,000 Base Bid Project Plus Al- ternative"02"$520 000 Base Bid Project Mus Al- ternatives "02"and "01" $600,000 Base Bid Project Plus Al- ternatives "02", '01", and"N2"$710,000 Base Bid Project Plus Al- ternatives"02",Ol","N2" and"Nl"$870,000 A Dre-bid meeting will be held on Monday, May 22, 2006 at 10:00 a.m. at the Public Works Depart- ment to cover the Coun- ty's Bidder Outreach Pro- gram. Prospective bid- tlers attendance is rec- ommended but not man- datory. Contract Documents,in- cluding plans and specifi- cations, may be viewed and/or obtained at the Public Works Depart- ment, C.C. Rich Building, 255 Glacier Drive, Marti- nez,California 94553-4897, Monday - Thursday (7:00 a.m. - 12 Noon and 1:00 N. - 5:00 p.m.) (closed Fridays). To obtain plans and specifications a serv- ice charge is required in the amount of $ 34,00 (sales tax included). Plans and specifica- tions may be ordered by mail for an additional shipping and handling fee of$3.00. Checks shall be made payable to 'The County of Contra Costa' and be mailed to the above address. The Agency does not guaran- tee the arrival of the plans and specifications in time for bidding. Plans and specifications will not be sent overnight mail. This project is to be ad- vertised pursuant to Pub- lic Contract Code 22037. This contract is subject to state contract nondis- crimination and compli- ance requirements pur- suant to Government Code,Section 12990. The Contractor shall i possess a Class A or Class C-12 Contractor's License at the time the j Contract is awarded. Bids must cover the en- tire project, and neither partial nor contingent r I 'I } bids will be considered. The successful bidder shall furnish a payment bond and a performance bond. The Board has ascer- tained the general pre- vailing rate of wages ap- plicable to this work. The prevailing rate of per diem wages is on file with the Clerk of the Board of Supervisors,and is incor- porated herein by refer- ence thereto,the same as if set forth in full herein. For any classification not included in the list, the minimum wage shall be the general prevailing rate for Contra Costa County. The bid opening date may be extended by ad- dendum issued by the Agency no later than June 2,2006,in which case any bids submitted for the original bid opening will be returned unopened and sealed bid proposals for the extended bid opening shall be submit- ted on or before June 20 2006,at 2:00 P.m.,and wil( be opened, read and re- corded at the same place specified above. All pro- posals received late will be returned unopened. The said Board re- serves the right to reject any and all bids or any portion of any bid and/or waive any irregularity in any bid received. For questions regard- ing the project contact Hannah Wong,Design Di- vision,at(925)313-2381. By order of the Board of Supervisors as the gov- erning body of the Contra Costa County Flood Con- trol and W2006 ater Con- servation District John Cullen Clerk of the Board of Su- pervisors and County Ad- ministrator By EMY L.SHARP,Deputy Dated:MAY 04,2006 Legal CCT 5614 Publish May 22,2006 1 r i I j �— "Contra Costa Times To: EShar@cob.cccounty.us Legals" cc: <cctlegals@cctimes.c Subject: 2006 GRAYSON CREEK CHANNEL EXCAVATION o om> 05/08/2006 09:47 AM Please respond to cctlegals THE FOLLOWING a-mail contains pertinent information; please read it carefully in its entirety. PLEASE NOTE:All of our offices will be closed Memorial Day, Monday, May 29, 2006. Good Morning. If you have any questions regarding the legal notice confirmed below,please reference the LEGAL NUMBER provided. Only e-mail to cctlegals ,cctimes.com regarding Contra Costa Times, Concord Transcript, or Contra Costa Sun legal notices. ** LEGAL SCHEDULE CONFIRMATION ** TYPE: In-Column Liner, Classified Section LEGAL NUMBER: 5615 PO#: 1158 Publication: CCT Run Date(s): 05/22 Legal Acct#: 200 4197 Total Amount: $238.00 FOR YOUR INFORMATION - Revisions/Cancellations: I will need a cancellation request referencing the LEGAL NUMBER—or all changes attached in a final draft Microsoft Word Document—e-mailed to cctlegalsta?cctirnes.com by no later than 4 PM, Thus., 05/18. Otherwise, the wording of the legal will publish as you e-mailed. Thanks! Anashia Lloyd Legal Advertising Coordinator (925) 943-8019 (925) 943-8359—fax Contra Costa Times ATTN: Legal Dept. P.O. Box 4718 Walnut Creek, CA 94596 cettegals@cctimes.com LEGAL PUBLICATION REQUISITION�,,2/ s Contra Costa County rr'i COLN'� FROM: Clerk of the Board TO: Contra Costa Times 651 Pine St., Room 106 P.O. Box 4718 Pine Street, Martinez 94553 Walnut Creek, CA 94596 FAX No. 925-943-8359 Requested by: EMY L. SHARP Date: MAY 04, 2006 Phone No.: 925-335-1903 Reference No. 1158 Org.:_7520_Sub Object:_2190 Task:_SAS_Activity : 6139354-06 Publication Date (s) May 22, 2006 No. of Pages: (3) LEGAL PUBLICATION : 2006 GRAYSON CREEK CHANNELEXCAVATION *** Immediately upon expiration of publication, ** send in one affidavit for each publication in order that the auditor may be authorized to pay you bill. (E-MAIL) c Authorized Signature: Please confirm date of publication an receipt of this fax. . Contra Costa County Flood Control and Water Conservation District 255 Glacier Drive, Martinez, California 94553-4897 NOTICE TO CONTRACTORS The Chief Engineer will receive sealed bids at the Public Works Department, C.C. Rich Building, 255 Glacier Drive, Martinez, California 94553-4897, until 2 o'clock p.m., on June 6, 2006, at which time they will be publicly opened and read, for: 2006 GRAYSON CREEK CHANNEL EXCAVATION. General work description: Remove up to approximately 23,000 cubic yards (Base Bid Project Plus Alternatives) of channel excavation ft-om the designated areas of Grayson Creek Channel between Highway 4 and Chilpancingo Parkway in the Pleasant Hill area. ENGINEER'S ESTIMATE: Base Bid Project $360,000 Base Bid Project Plus Alternative"D" $445,000 Base Bid Project Plus Alternative"D" and"C1" $560,000 Base Bid Project Plus Alternatives "D", "Cl", and "C2" $665,000 A pre-bid meeting will be held on Monday, May 22, 2006 at 10:00 a.m. at the Public Works Department to cover the County's Bidder Outreach Program. Prospective bidders attendance is recommended but not mandatory. Contract Documents, including plans and specifications, may be viewed and/or obtained at the Public Works Department, C.C. Rich Building, 255 Glacier Drive, Martinez, California 94553-4897, Monday - Thursday (7:00 a.m. - 12 Noon and 1:00 p.m. - 5:00 p.m.) (closed Fridays). To obtain plans and specifications a service charge is required in the amount of$38.00 (sales tax included). Plans and specifications may be ordered by mail for an additional shipping and handling tee of 53.00. Checks shall be made payable to 'The County of Contra Costa and be mailed to the above address. The Agency does not guarantee the arrival of the plans and specifications in time for bidding. Plans and specifications will not be sent overnight mail. This project is to be advertised pursuant to Public Contract Code 22037. This contract is subject to state contract nondiscrimination and compliance requirements pursuant to Government Code, Section 12990. The Contractor shall possess a Class A or Class C-12 Contractor's License at the time the Contract is awarded. Bids must cover the enure project, and neither partial nor contingent bids will be considered. The successful bidder shall furnish a payment bond and a performance bond. The Board has ascertained the general prevailing rate of wages applicable to this work. The prevailing rate of per diem wages is on file with the Clerk of the Board of Supervisors, and is incorporated herein by reference thereto, the same as if set forth in full herein. For any classification not included in the list, the minimum wage shall be the general prevailing rate for Contra Costa County' The bid opening date may be extended by addendum issued by the Agency no later than June 2, 2006, in which case any bids submitted for the original bid opening will be returned unopened and sealed bid proposals for the extended bid opening shall be submitted on or before June 20, 2006, at 2:00 p.m., and will be opened, read and recorded at the same place specified above. All proposals received late will be returned unopened. The said Board reserves the right to reject any and all bids or any portion of any bid and/or waive any irregularity in any bid received. For questions regarding the project contact Hannah Wong, Design Division, at (925) 313-2381. By order of the Board of Supervisors as the governing body of the Contra Costa County Flood Control and Water Conservation District John Cullen Clerk of the Board of Supervisors and County Administrator By EMY L. SHARP Deputy Dated: MAY 04, 2006 Publication dates: MAY 22, 2006 i i CONTRA COSTA COUNTYPUBLIC WORKS DEPARTMENT 255 GLACIER DRIVE, MARTINEZ, CALIFORNIA DATE: May 3, 2006 TO: Jane Pennington, Chief Clerk of the Board Attn: Emy Sharp, Deputy Clerk, Clerk of the Board eshar( cob.co.contra-costa.ca.us FROM: Michael Hollingsworth, Assistant Public Works Director 313-2231 SUBJECT: Authorization to Advertise "2006 Grayson Creek Channel Excavation" This is your Authorization to advertise the attached Notice to Contractors for the "2006 Grayson Creek Channel Excavation" project and publish the Notice to Contractors under Public Contract Code: 22037 in the Contra Costa Times. The attached Board Oder (unexecuted copy) authorizing the Public Works Director to advertise this project was approved on May 2, 2006 agenda item number C.28. The bid due date for this project is: June 6, 2006 Project No: 7520-6B9354-06 The environmental document project name refers to work in Walnut Creek and Grayson Creek, This construction project involves the work only in Grayson Creek, therefore the difference in project name. Mn:hw:kp 0:ADesipnACoriespondencoi2006 Desilt Grayson Creek\AdvertiseAD-7 2006 Graysoa Civek Channel Excavation.doe Attachments:Notice to Contractors, Board Order(Unexecuted copy) I i r Contra Costa Times To: EShar@cob.cccounty,us Legals" cc <CCtlegals@CCtimes.0 Subject: 2006 WALNUT CREEK CHANNEL DESILT om> 05/08/2006 0936 AM Please respond to cct)egals THE FOLLOWING e-mail contains pertinent information; please read it carefully in its entirety. PLEASE NOTE:All of our offices will be closed Memorial Dnv, Monday, Mtkv 29, 2006. Good Morning. If you have any questions regarding the legal notice confinned below, please reference the LEGAL NUMBER provided. Only e-mail tocctle2als(dcctimes.coln regarding Contra Costa Times, Concord Transcript, or Contra Costa Sun legal notices. LEGAL SCHEDULE CONFIRMATION TYPE: In-Column Liner, Classified Section LEGAL NUMBER: 5614 PO#: 1157 Publication: CCT Run Date(s): 05/22 Legal Acct#: 200 4197 Total Amount: $246.40 FOR YOUR INFORMATION - Revisions/Cancellations: I will need a cancellation request referencing the LEGAL NUMBER—or all changes attached in a final draft Microsoft Word Document —e-mailed to cctleggals(a—?ectimes.com by no later than 4 PM, Thurs., 05/18. Otherwise, the wording of the legal will publish as Von e-mailed. Thanks! Anashia Lloyd Legal Advertising Coordinator (925) 943-8019 (9215) 943-8359 —fax Contra Costa Times ATTN: Legal Dept. P.O. Box 4718 Walnut Creek, CA 94596 cctlegals&ctimes.corn cctlegals@cctimes.co To: EShar@cob.cccounty.us Subject: Re: 2006 WALNUT CREEK CHANNEL DESILT w 05/04/2006 02:58 PM Please respond to cctlegals The email that you have just sent has been received by the Legals desk at Contra Costa Newspapers/Hills Newspapers. Legal Notices will be processed based on the next available deadline (or requested publication date) . If a quote or proof has been requested, they will be provided once the notice has been processed. If you are requesting general information, we will respond as soon as possible. Thank you. i i LEGAL PUBLICATION REQUISI:TION�. N,, Contra Costa County FROM: Clerk of the Board TO: Contra Costa Times 651 Pine St., Room 106 P.O. Box 4718 Pine Street, Martinez 94553 Walnut Creek, CA 94596 FAX No. 925-943-8359 Requested by: EMY L. SHARP Date: MAY 049 2006 Phone No.: 925-335-1903 Reference No. 1157 Org.:_7520_Sub Object:-2190-Task:-SAS-Activity : 6B9353-06 Publication Date (s) May 22, 2006 No. of Pages: (3) LEGAL PUBLICATION 2006 WALNUT CREEK CHANNEL DESILT ** Immediately upon expiration of publication, *** send in one affidavit for each publication in order that the auditor may be authorized to pay you bill. (E-MAIL) Authorized Signature: I Please confirm date of publicatl�on nd receipt of this fax. Contra Costa County Flood Control and Water Conservation District 255 Glacier Drive, Martinez, California 94553-4897 NOTICE TO CONTRACTORS The Chief Engineer will receive sealed bids at the Public Works Department, C.C. Rich Building, 255 Glacier Drive, Martinez, California 94553-4897, until 2 o'clock p.m., on June 6, 2006, at which time they will be publicly opened and read, for: 2006 WALNUT CREEK CHANNEL DESILT. General work description: Remove up to 38,000 cubic yards of channel excavation (Base Bid Project Plus Alternatives) from designated areas of Walnut Creek Channel between Concord Avenue and Drop Structure Number 1 (downstream State Route 242) in the Concord area. Engineer's cost estimate: Base Bid Project $ 440,000 Base Bid Project Plus Alternative"02" $520,000 Base Bid Project Plus Alternatives"02" and"01" $600,000 Base Bid Project Plus Alternatives "02", "01", and"N2"$710,000 Base Bid Project Plus Alternatives "02", 01", "N2"and"N l"$870,000 A pre-bid meeting will be held on Monday, May 22, 2006 at 10:00 a.m. at the Public Works Department to cover the County's Bidder Outreach Program. Prospective bidders attendance is recommended but not mandatory. Contract Documents, including plans and specifications, may be viewed and/or obtained at the Public Works Department, CC. Rich Building, 255 Glacier Drive, Martinez, California 94553- 4897, Monday - Thursday (7:00 a.m. - 12 Noon and 1:00 p.m. - 5:00 p.m.) (closed Fridays). To obtain plans and specifications a service charge is required in the amount of $ 34.00 (sales tax included). Plans and specifications may be ordered by mail for an additional shipping and handling fee of$ 3.00. Checks shall be made payable to 'The County of Contra Costa' and be mailed to the above address. The Agency does not guarantee the arrival of the plans and specifications in time for bidding. Plans and specifications will not be sent overnight mail. This project is to be advertised pursuant to Public Contract Code 22037. This contract is subject to state contract nondiscrimination and compliance requirements pursuant to Government Code, Section 12990. The Contractor shall possess a Class A or Class C-12 Contractor's License at the time the Contract is awarded. Bids must cover the entire project, and neither partial nor contingent bids will be considered. The successful bidder shall furnish a payment bond and a performance bond. The Board has ascertained the general prevailing rate of wages applicable to this work. The prevailing rate of per diem wages is on file with the Clerk of the Board of Supervisors, and is incorporated herein by reference thereto, the same as if set forth in full herein. For any classification not included in the list, the minimum wage shall be the general prevailing rate for Contra Costa County. The bid opening date may be extended by addendum issued by the Agency no later than June 2, 2006, in which case any bids submitted for the original bid opening will be returned unopened and sealed bid proposals for the extended bid opening shall be submitted on or before June 20, 2006, at 2:00 p.m., and will be opened, read.and recorded at the same place specified above. All proposals received late will be returned unopened. The said Board reserves the right to reject any and all bids or any portion of any bid and/or waive any irregularity in any bid received. For questions regarding the project contact Hannah Wong, Design Division, at (925) 313-2381. By order of the Board of Supervisors as the governing body of the Contra Costa County Flood Control and W2006 ater Conservation District John Cullen Clerk of the Board of Supervisors and County Administrator By EMY L. SHARP Deputy Dated: MAY 04, 2006 Publication dates: MAY 22, 2006 I CONTRA COSTA COUNTYPUBLIC WORKS DEPARTMENT 255 GLACIER DRIVE, MARTINEZ, CALIFORNIA DATE: May 3, 2006 TO: Jane Pennington, Chief Clerk of the Board" Attn: Emy Sharp, Deputy Clerk, Clerk of the Board esharQcob.co.contra-costa.ca.us FROM: Michael Hollingsworth, Assistant P lic Wor ctor G� 313-2231 SUBJECT: Authorization to Advertise "2006 Grayson Creek Channel Ex2 ation" This is your Authorization to advertise the attached Notice to Contractors for the "2006 Grayson Creek Channel Excavation" project and publish the Notice to Contractors under Public Contract Code: 22037 in the Contra Costa Times. The attached Board Order (unexecuted copy) authorizing the Public Works Director to advertise this project was approved on May 2, 2006 agenda item number C.28. The bid due date for this project is: June 6, 2006 Project No: 7520-6B9354-06 The environmental document project name refers to work in Walnut Creek and Grayson Creek. This construction project involves the work only in Grayson Creek, therefore the difference in project name. MH:hw:kp GADesign\Correspondence\2006 Desilt Grayson CreekiAdvertise\D-7 2006 Grayson Creek Channel Excava6on.doc Attachments:Notice to Contractor's,Board Order(Unexecuted copy) i RECEVED i i 1 1 MAY 0 4 2006 CLERK BOARD OF SUPERVISORS CONTRA COSTA CO.