HomeMy WebLinkAboutMINUTES - 05131997 - C15 TO: BOARD OF SUPERVISORS
FROM: J. MICHAEL WALFORD, PUBLIC WORKS DIRECTOR
DATE: MAY 13, 1997
SUBJECT: ACCEPT THE PETITION AND ADOPT THE RESOLUTION SETTING THE PUBLIC
HEARING FOR THE FORMATION OF THE CALIFORNIA TRADEWINDS GEOLOGIC
HAZARD ABATEMENT DISTRICT, SUBDIVISION 7838, BAY POINT AREA. PROJECT
NUMBER 6X5090
Specific Request(s)or Recommendation(s)&Background&Justification
I. Recommended Action:
1. ACCEPT the Petition for the formation of the California Tradewinds Geologic Hazard Abatement
District (GHAD), and
2. ADOPT the Resolution SETTING the hearing date initiating the proceedings on the proposed formation
of the California Tradewinds GHAD on Tuesday, June 10, 1997, at 10:30 a. in. in Room 107 of the
Board of Supervisors' Chambers, 651 Pine Street,Martinez, California, as the time and place for a public
hearing to consider oral and written objections or comments concerning the California Tradewinds
GHAD.
H. Financial Impact:
There will be no impact to the General Fund. All costs will be covered with revenue generated through
parcel assessments for the GHAD.
III. Reasons for Recommendations and Background:
-The Conditions of Approval for Subdivision 7838 required that a GHAD be formed in order to mitigate the
potential for soil movement in this development. The District boundaries and the subdivision boundaries are
the same. All of the subdivision parcels are currently owned by Kaufman and Broad of Northern California,
who is petitioning the Board to form the California Tradewinds GRAD.
r/
Continued on attachment: x Yes SIGNATURE: ;
RECONM ENDATION OF COUNTY ADMINISTRATOR
RECONINIENDATION OF BOARD COMMITTEE
APPROVE OTHER
SIGNATURE(S):
ACTION OF BOARD ON: 1 q 9 _ APPROVED AS RECOMMENDED ✓ OTHER
VOTFjOF SUPERVISORS
UNANIMOUS(ABSENT )
AYES: NOES:
ABSENT: ABSTAIN:
SE:cs
g:\EngSvc\SpDist\BO\CTGHAEil3.t5
Contact: Skip Epperly,(510)313-2253 1 hereby Csf*that this Is a true and conedof
Orig.Div.: PW(Special Districts) en action taken and entered on the minutes tt
cc: Auditor-Controller Board of Supervisors on the date shum
Accounting ATTESTED:
Engineering Services PHIL SATCHE OR,Cletk of the board
Community Development of Supervisors and County AdminlWata
A.Lindgren,McCutchen,Doyle,Brown&Emerson ,
S.Makdessi,Terrasearch Inc. ✓)1G., __
CALIFORNIA TRADEWINDS GEOLOGIC HAZARD ABATEMENT DISTRICT
MAY 13, 1997
PAGE TWO
III. Reasons for Recommendations and Background: (Continued)
The Plan of Control describes the work contemplated for this district, including maintenance, monitoring,
and funding. Funding for the GRAD will be based on a parcel assessment from each improved lot in the
subdivision. It is anticipated that approximately $6,00047,000 per year will be accumulated as a reserve
during the initial three year build-out period. This reserve will only be used for general maintenance,
repair of slides and erosion control within the District. Parcel assessments will continue to be collected
annually and used for maintenance. Unexpended funds will augment the reserve for the following year.
It is anticipated that the homeowners of the subdivision will assume the responsibilities as the Board of
Directors of the GHAD after the first four years.
IV. Conseauences of Negative Action:
The project will not be able to proceed because no building permits may be issued without a GHAD being
formed.
THE BOARD OF SUPERVISORS OF CONTRA COSTA COUNTY,CALIFORNIA
Adopted this Resolution on May 13, 1997, by the following vote:
AYES: Supervisors Rogers, Uilkema, Gerber, Canciamilla, DeSaulnier
NOES: None
ABSENT: None
ABSTAIN: None
RESOLUTION NO.97/ 241
SUBJECT: Initiate Proceedings to Form a Geologic Hazard Abatement District and Set a Public
Hearing on the Petition for Formation of the California Tradewinds Subdivision 7838
Geologic Hazard Abatement District.
The Board of Supervisors of Contra Costa County RESOLVES THAT:
1. On May 13, 1997, pursuant to the provision of Division 17 of Public Resources Code,
sections 26550 et seq., this board was presented with a Petition for Formation of the
California Tradewinds Subdivision 7838 Geologic Hazard Abatement District (the
"GHAD Petition"). The Board concludes that the GHAD Petition is in the form
prescribed by Sections 26551 and 26552 of the Public Resources Code.
2. This Resolution is made pursuant to the provision of Division 17 of Public Resources
Code,sections 26500 et seq. This Board has been presented with and reviewed the Plan
of Control for the California Tradewinds Subdivision 783 8 GHAD (the"Plan of Control")
and determined that the health, safety and welfare require formation of a District.
3. SET a public hearing (the "Hearing") on the proposed formation of the GHAD on
Tuesday, June 10, 1997 at 10:30 a.m. in Room 107 of the Board of Supervisors'
Chambers, 651 Pine Street, Martinez, California 94553. At the Hearing, any objections
to the proposed formation shall be presented.
4. Notice of the Hearing shall be mailed first-class, postage prepaid, in the United States
Mail, at least 20 days preceding the date of the Hearing, to each owner of real property
within the GHAD as shown on the last equalized County assessment roll, or the State
Board of Equalization assessment roll, as the case may be. Notice of the Hearing shall
include a copy of the GHAD Petition. Notice of the Hearing shall set forth the time, date,
and place of the Hearing. Notice of the Hearing shall also briefly describe the purpose of
the Hearing, and indicate where the Plan of Control may be reviewed or duplicated, at a
cost not to exceed the cost of duplication. Notice of the Hearing shall also set forth the
address where objections to the proposed formation may be mailed or otherwise delivered
up to and including the time of the Hearing.
5. At any time not later than the time set for hearing objections to the proposed formation,
any owner of real property within the proposed GHAD may make a written objection to
the formation. Such objection shall be in writing, shall contain a description of the land
by lot, tract, and map number, and shall be signed by such owner. Objections shall be
mailed or delivered as specified in the notice procedure in Paragraph 4 of this Resolution.
If the person whose signature appears on such an objection is not shown on the assessment
roll last equalized by the County as the owner of the subject property, the written objection
shall be accompanied by evidence sufficient to indicate that such person is the owner of
such property.
I talby asi ft Met thle Is s true and Coned My of
1rt actlon taken and entered on the minutes all-ft
Board oIs upervlso on the date shown.
SE:cs to 1
g:\EngSvc\SpDist\CTGHAD13.t5 PHIL BATH R,Clerk Of the board
of supervisors nd County Administrator
Crit.Dept: Public Works Department(Special Districts)
Contact: Slap EpperlyCounty
Administrator 53
cc: County Admwstrator
Auditor-Controller
Accounting
County Counsel
J.Bayless,Kaufman&Broad
A.Lindgren,McCutchen,Doyle,Brown&Enerson
RESOLUTION NO. 97/241
PETITION FOR FORMATION OF
THE CALIFORNIA TRADEWINDS SUBDIVISION 7838
GEOLOGIC HAZARD ABATEMENT DISTRICT
PURSUANT TO DIVISION 17 (commencing with Section 26500)
OF THE PUBLIC RESOURCES CODE
OF THE STATE OF CALIFORNIA
TO: The Clerk of the Board of Supervisors
of Contra Costa County
The undersigned owners of land within the boundaries of the district proposed in
this petition hereby request that the Board of Supervisors initiate proceedings to form a Geologic
Hazard Abatement District(the "GHAD")pursuant to the provisions of Division 17 of the Public
Resources Code, Sections 26500 et seq.
(a) This petition is made pursuant to Division 17 of the Public Resources
Code with particular reference to Sections 26550.5, 26552 and 26553 of said Code.
(b) Opposite the signature of each of the petitioners is an indication of the lot,
tract and map number or other legal description sufficient to identify the signature of the
petitioner as that of the owner of land within the territory proposed to be included within the
GHAD.
(c) Opposite the signature of each petitioner is an indication of the date on
which said petitioner's signature was affixed to this petition.
(d) The following documents are attached to this petition and are incorporated
herein by this reference as if set forth in full in this petition:
I. As Exhibit A, a map of the boundaries of the territory to be
included within the proposed GHAD;
2. As Exhibit B, a legal description of the boundaries of the territory
LO be included within the proposed GHAD; and
3. As Exhibit C, a plan of control prepared by an engineering
geologist certified pursuant to Section 7822 of the Business and Professions Code which
describes the actual or threatened landslides, land subsidence, soil erosion and other natural or
unnatural movements of land or earth and the plan for their prevention, mitigation, abatement
and control thereof.
i
I
SIGNATURE ADDRESS DATE
�- L.g,r-r- J k• � fit"'"` ti t �� �-�
1 All that certain real property located
in the County of Contra Costa
described as follows: Parcels A
and B,and Lots 1 through 46,
inclusive,as said Parcels and Lots
are shown on the map entitled
Subdivision 7838,filed May 30,
1996, in the office of the Recorder
of the County of Contra Costa,
California,Official Records, in
Book 387 of Maps,at Pages 10
through 15.
CA970230.036
2
S
N
• $ J� �a S i
k
X
k rlp
Q
y 7 J n
R n
04-b�
`R 1J SQM,I{3Qyb1
Poll a R * R
k
Exhibit B
Legal Description Of The Boundaries Of
The California Tradewinds Subdivision 7838
Geologic Hazard Abatement District
All that certain real property located in the County of Contra Costa described as follows:
Parcels A and B, and Lots 1 through 46, inclusive, as said Parcels and Lots are shown on the map
entitled Subdivision 7838, filed May 30, 1996, in the office of the Recorder of the County of
Contra Costa, California, Official Records, in Book 387 of Maps, at Pages 10 through 15.
i
1 Exhibit C
Plan Of Control For The
California Tradewinds Subdivision 7838
Geologic Hazard Abatement District
1
EOLOGIC HAZARD ABATEMENT DISTRI<
( PLAN OF CONTROL
l; on
CALIFORNIA TRADEWINDS i
SUBDIVISION 7838
(� Evora Road, Bay Point
Contra Costa County, California
for
II KAUFMAN AND BROAD
OF NORTHERN CALIFORNIA ;
ji
TECHNICAL.ENGINEERS AND
1
..
GEOLOGISTS
}
wp
Exhibit C
r
t
Plan Of Control For The
California Tradewinds Subdivision 7838
1 Geologic Hazard Abatement District
[
EOLOGIC HAZARD ABATEMENT DISTRI(.
PLAN OF CONTROL
on
CALIFORNIA TRADEWINDS
SUBDIVISION 7838
Evora Road, Baa- Point
Contra Costa County, California
for
[ KAUFMAN AND BROAD
OF NORTHERN CALIFORNIA
"GEOTECHNICAL ENGINEERS GEOLOGISTS
GEOTECHNICAL ENGINEERS AND GEOLOGISTS
3EA"Cl
11840 DUBLIN BOULEVARD;DUBLIN,CALIFORNIA 94568 (510)833-9297 FAX(510)833-9548
I >
Project No. 6319.poc
30 January 1997
Mr.'John Bayless
II Kaufman and Broad of Northern California
3130 Crow Canyon Place, Suite 300
( San'Ramon, California 94583
i Subject: California Tradewinds, Subdivision 7838 J
Evora Road, Bay Point
Contra Costa County, California
GEOLOGIC HAZARD ABATEMENT DISTRICT
PLAN OF CONTROL
Dear Mr. Bayless:
In accordance with your authorization, TERRASEARCH, inc. has prepared a Geologic Hazard
Abatement District Plan of Control for the above referenced site.
The following is a copy of the report which presents the results of our plan of control.
Should you have any questions relating to the contents of this report or require any additional
information, please contact our office at your convenience.
- Very truly yours,
Reviewed by: Q�pFESS/,/)' TERR,4SEARCH, inc.
l Qc`O oN MAKS
C50U' Z
307
rn
Simon Makdessi, P.E. _ Robert D. Campbell, R.G.
Senior. Engineer Exp.6-30-97 Project Geologist
s CIVIL
r�rFOF CAUF�P�\P
Richard Rowland, C.E.G.
Senior Geologist
/tf
4 Copies: 6 to Kaufman and Broad
(Attn: Mr. John Bayless)
:V
\, SINCE 1969
6840 VIA DEL ORO, SUITE 110, SAN JOSE,CALIFORNIA 95119-1348 (408)362-4920 FAX (408)362-4926
/ ect No. 6319.poc GHAD Plan of Control/California Tradewinds 30 January 1997
GEOLOGIC HAZARD ABATEMENT
DISTRICT PLAN OF CONTROL
I 1.0 INTRODUCTION
' . The proposed California Tradewinds project is a 46 lot single family residential development
located on the northeast and northwest corners of the intersection of Evora Road and Driftwood
Drive in the Bay Point area of Contra Costa County. Mass grading for the project has been
recently completed. Currently, grading and construction of a 1 million-gallon water tank and
r associated access road is in progress to the west of the project..
N
As required by the County, a Geologic Hazard Abatement District (GHAD) will be formed to
specifically address geologic related issues that may potentially effect the public and private
improvements. A GHAD will collect sufficient revenue to finance the inspection and
maintenance of planned drainage improvements and/or facilities installed to mitigate known
geologic hazards or for potential future geologic hazards for the useful life of the project. This
will also include the costs of any repairs and/or construction of improvements, as needed.
The purpose of this Plan of Control document is to describe potential geologic hazards, prepare
a plan that addresses prevention, mitigation, abatement and control of such hazards, and
estimate the associated costs. The private open space shall be managed by the GHAD.
1.2 Site History
Previous geotechnical and geologic studies have been performed for the.project and are
presented in the references section of this report.
Prior to development, the site topography consisted of moderately to locally steep hillsides that
slope to the axis of a southwest-northeast trending drainage swale. In 1992, mass grading
operations for the subject tract and the adjacent California Skyline (Tracts 7737 & 7597)
project were performed. Earthwork consisted of filling the swale area to construct Driftwood
TERRASEARCH, inc. Page 3
n
ct /0* 6319.poc GRAD Plan of ControVCalifornia Tradewinds 30 January 1997
/
tc/l, and placing engineered fill to within 10 feet of the design grade for the subject tract.
i {
bdrains were installed within the swale area prior to the placement of engineered fill that
/ ranges up to approximately 50 feet in thickness. The approximate location of these subdrains
is shown on attached Figure 1. During July 1996 up to 10 feet of additional engineered fill
was placed to achieve design grade.
1
:r.
2.0 GENERALIZED GEOLOGIC AND GEOTECHNICAL CONDITIONS
r
2.1 Site Geology
The proposed district,lies within moderately to locally steep hillslopes (up to 45%) within the
outcrop belt of sedimentary strata that strike northwest and moderately dip (at 14 to 44
degrees) to the northeast. On the western-southwestern portion of the district, these strata
consist of the lower sandstone member of the Markley Formation (interbedded shales and
sandstone units) of Miocene Age and marine in origin. The eastern-northeastern portion of the
.�. district consists of a clayey sandstone member of the Tehama Formation (clayey sandstones,
clean sandstones, and conglomerate units) .of Pliocene Age and non-marine in origin. The
Markley and Tehama Formations are separated by the Lawlor Tuff (a pumaceous lapilli tuff
of andesitic composition) of Pliocene Age, which is approximately 50 to 100 feet in thickness,
and outcrops in the northwest corner of the subject site. A site geology map summarizing our
field observations of geology is attached as Figure 1.
The San Francisco Bay Area is noted as one of the most seismically active areas in the entire
United States with recent historical great earthquakes being continually recorded since 1836
(moment magnitude [M]=7.0 on the Hayward Fault) to the present. Earthquake damage to
�- structures occurs as two main categories: a) primary deformation such as surface rupture and
X:
ground shaking; and b) secondary (induced) failure such as lurch cracking, landsliding,
liquefaction, and differential compaction.
The major active faults, as defined by the Alquist-Priolo Earthquake Fault Zones Act, within
ra 50-mile radius of the subject site, include: The Concord Fault, located approximately 4 miles
to the west; the Green Valley Fault, located approximately 7 miles to the north-northwest; the
Marsh Creek-Greenville Fault, located approximately 10 miles to the south-southeast; the
Calaveras Fault, located approximately 16 miles to the southwest; the Hayward Fault, located
18 miles to the west; the Rogers Creek Fault, located approximately 26 miles to the northwest;
TERRASEARCH, inc. Page 4
i Project,No. 6319.poc GRAD Plan of Control/California Tradewinds 30 January 1997
and the northern portion of the San Andreas Fault, located approximately 40 miles to the west
of the subject site.
2.21 Description of Geologic Hazard
i
Section 26507 of the Public Resources Code, broadly defines a geologic hazard as an actual
or threatened landslide, land subsidence, soil erosion, earthquake fault movement or any other
natural or un-natural movement of land and/or earth.
Specifically, for this project, the main geologic hazards of concern include:
a) Landsliding
b) Erosion
C) Earthquake shaking
d) Fault rupture
e) Settlement of the engineered fill.
2.21 Landsliding
According to the U.S. Geological Survey (Ellen and Wentworth, 1995), the geologic units in
the site vicinity are moderately susceptible to slope failure. The neighboring subdivision to the
north contained several slope failures prior to development. According to published mapping
of the U.S. Geological Survey (Nilsen, 1975), along with our site-specific investigation
(Terrasearch, 1993) there is no evidence of landslides having occurred on the site. However,
a possibility exists of slope failures developing in the future. The most likely type of slope
failure appears to be a shallow soil-slump, but there is some potential for deep-seated failures
involving weathered bedrock.
2.22 Erosion
Risk of erosion is greatest in areas where there exists concentrated storm runoff on natural
. slopes, graded slopes, building pads, and un-vegetated cut and/or fill slopes. It is presumed
that all graded slopes within the open space area will be hydroseeded prior to the onset of this
TERRASEARCH, inc. Page 5
r.
` Project No. 6319.poc GHAD Plan of Control/California Tradewinds 30 January 1997
year's winter season. Revegetation of private lots will be the responsibility of the, homeowner.
In some areas cut slopes will expose sandstone and tuffaceous bedrock.' Such slopes may be
difficult to vegetate. Some erosion potentially exists on these slopes if vegetation growth does
not root properly, particularly during.the first rainstorm of the fall or after a fire.
2.23 Earthquake Shaking
Ground shaking is related to velocity, amplitude, and duration of earthquake vibrations.
Damage from shaking is caused by the transmission of earthquake vibrations from the ground
to the structure. The most destructive effects of an earthquake are usually seen where the
ground is unstable and structures are poorly designed and constructed. The most probable
source of significant seismic shaking is the Concord Fault, which lies approximately 4 miles
to the west of the site. For the Concord Fault, the maximum credible earthquake (M.C.E.) has
been estimated at 7.1 by A.B.A.G (1995) with an average repeat interval of approximately 319
years (Wesnousky,_ 1986). Based on the attenuation relationship formulated by Seed & Idriss
(1982), anticipated peak horizontal bedrock and soil accelerations at the site would be
approximately 0.55g and 0.50g for the M.C.E, respectively. , This would produce repeatable
accelerations of about 0.36g in bedrock and 0.33g in stiff soil according to the relationship
formulated by Ploessel Slossen (1974).
Any of the above listed active faults can result in an earthquake with M greater than 6.5, and
are expected to produce moderate to strong ground shaking at the subject site.
Liquefaction and lurch cracking are not significant hazards, because the lots at the subject site
are underlain by engineered fill consisting predominantly of clayey materials which are placed
on bedrock.
2.24 Fault Rupture
A regional fault map illustrating known active and inactive faults relative to the site is shown
on Figure 1. As shown on this map, no known active faults (as mapped by the Alquist-Priolo
Earthquake Fault Zones Act) are believed to exist within the boundaries of the site, and fault
rupture is therefore not anticipated.
TERRASEARCH, inc. Page 6
Project No. 6319.poc GHAD Plan of Control/California Tradewinds" 30.January 1997
2.25 Settlement of Engineered Fill
The engineered fill placed during 1990 and 1996 will experience settlement due to its own
weight. Total settlement of the fill placed in 1990 is estimated* to be of the order of 4 to 5
inches. It is estimated to date that 3 to 4 inches of total settlement may have occurred. The
remaining settlement of the fill placed in 1990 and that of the recently placed fill is expected.
to be of the order of 1 to 2 inches and be relatively minor. The proposed structures will be
founded on a slab foundation system which will adequately tolerate this estimated settlement.
3.0 CONTROL OF HAZARDS
The proposed district shall retain geologic and/or geotechnical consultants to make periodic
inspections to evaluate the performance of the natural and excavated slopes, the surface
drainage and ditches. The inspections should look for signs of slope failure, accelerated
erosion, or drainage blockages, both surface and subsurface.
As mentioned earlier, the two main geologic hazards that exist and require control or mitigation
during the life of the project are landsliding and erosion. The .potential occurrence of these
hazards can be minimized by ensuring that adequate drainage and vegetation cover exists.
Drainage will control the flow of water over natural and filled land, while vegetation will
reinforce the surface soil, increase the soil infiltration rate, and reduce the extent and velocity
of surface (overland) flow.
The drainage facilities that will be constructed as part of the development will consist of
concrete lined V-ditches and benches on all cut and fill slopes greater than 30 feet in vertical
height. The benches and ditches prevent overland flow over the bench and onto the slope.
The benches and ditches will essentially intercept storm-water runoff flows over the face of
the slope such that the velocity of flow between the benches is reduced to levels that minimize
the potential for erosion, sedimentation, and development of soil slumps. Some sedimentation
is expected to occur and should the ditches become blocked due to sedimentation, soil
slumping, debris, or vegetation and the accumulation of water can not discharge to the drain
then there exists the possibility of concentrated flow over the bench and onto the slope causing
erosion and/or soil slumping. It is therefore important that the concrete-lined ditches be
inspected periodically to ensure that they are free of any debris, and that no cracks exist in the
concrete lining that may divert the flow of water away from the discharge point.
TERRASEARCH, inc. Page 7
Project No. 6319.poc GHAD Plan of Control/California Tradewinds 30 January 1997
Should erosion, fill movement, or slumping occur, temporary and permanent mitigation
measures could include the following:
TemporM Mitigation
a) Covering soil failure and/or erosional surface with plastic sheeting
b) Installation of hydroaugers
C) Sand bagging around affected area
d) Additional inspections to monitor site conditions.
C) Revegetation of disturbed area.
Permanent Mitigation
a) Complete removal and replacement of the failed zone with or without subdrains
b) Partial repair involving a buttress fill with or without subdrains
C) Construction of additional surface or subsurface drainage facilities.
4.0 MONITORING AND MAINTENANCE PROCEDURES
Monitoring of the slope and drainage system would consist of walking the length of all benches
and concrete lined ditches, walking the areas above and below the slopes, and observe the
condition of the slopes. The concrete ditches would be observed for evidence of cracks, heave,
or settlement of the ditch such that water flow direction has been altered. The ditches would
be observed for the presence of any debris or sedimentation. In addition, the uphill lip of the
ditch will be checked to ensure that it is below the ground surface and that water from the
slope does not flow underneath the ditch.
If any cracks larger than hairline are observed, these will be sealed with grout or epoxy and
if any debris is observed in_the ditches, the debris will be removed.
In order to assist in the monitoring and maintenance of facilities an As-Built grading/drainage
plan will be prepared by the project Civil Engineer at the completion of construction of
residences.
TERRASEARCH, inc. Page 8
Project No. 6319.poc CHAD Plan of ControUCalifornia Tradewinds 34 January 1997
5.0 FREQUENCY OF MONITORING
It is recommended that the above monitoring program be initiated in the fall of each year just
prior to the onset of winter. After the initial visit, two visits during the winter are
recommended. An additional visit should be made during or immediately after a major storm
event. If any problems develop, additional visits will be•required.
6.0 MONITORING AND MAINTENANCE COST ESTIMATE
Based on the above frequency of monitoring, the cost for administrating, performing the
monitoring and minor cleaning and/or grouting and preparation of a report is estimated to be
$6,000 to $7,000 per year.
This cost does not include the repair of any large scale soil slumps, erosion or blockage. The
occurrence of such situations is considered to be rare, and a precise estimate can not be made.
The additional cost with such repairs could range from $1,000 to $50,000 depending on the
magnitude of the event(s). It may be advisable to set up an initial fund account or increase the
amount of yearly funds by. $1,000 as a contingency to cover any future eventualities.
TERRASEARCH, inc. Page 9
Project No. 6319.poc GHAD Plan of Control/California Tradewinds 30 January 1997
7.0 REFERENCES
Association of Bay Area Governments, 1995, "On Shaky Ground": Publication No.
P95001EQK, April, 1995.
Ellen, S.D. and Wentworth, C.M., 1995, Hillside Materials and Slopes of the San Francisco
Bay Region, California. U.S.G.S. Geological Professional Paper 1357.
Mr. Skip Epperly of Contra Costa County.
Hart, W. E., 1994, Fault-Rupture Hazard Zones in California, Altamont Earthquake Fault
Zones Map, Altamont 7.5 Quadrangle, California, D.M.G. and U.S.G.S, 1994 and January 1,
1992.
Nilsen, T.H., 1975, Preliminary Photointerpretation Map of Landslide and Other Surficial
Deposits of Part of the Honker Bay 7-1/2' Quadrangle, Contra Costa County, California: U.S.
Geological Survey, Open File Map 75-277-20.
Ploessel, M.R., and Slossen, J.E., 1974, Repeatable High Ground Accelerations From
Earthquake-Important Design Criteria, in California Geology, California Division of Mines
and Geology, Preliminary Report 17.
Purcell, Rhoades & Associates, 1988. Soil and Geologic Report, Boeger Ranch Property, .West
Pittsburg, California": Report for Kaufman and Broad, Inc., dated Nov. 2, 1988 (their file No.
11-0102/4996-01).
Seed, H.B., and Idriss, J.M., 1982, Ground Motion and Soil Liquefaction During Earthquakes,
Monograph Series, Earthquake Engineering Institute.
Senate .Bill No. 1195, "Beverly Act", Chapter 1118, Division 17.
Stedman & Associates, October 1990. Vesting Tentative Map and Final Development Plan for
Boeger Ranch Property.
Terrasearch, Inc., 1993. "Geotechnical Investigation, California Skyline II, Subdivision 7838,
Evora Road and Driftwood Lane, Contra Costa County, California": consultant's report for
Kaufman and Broad of Northern California dated 23 September 1993 (Project No. 6319.7838).
Wesnousky, S.G., 1986, Earthquakes, Quaternary Faults, and Seismic Hazard in California,
Journal of Geophysical -Research, Vol. 91, No. B12, pp. 12,587-12,631, November 10, 1986.
TERRASEARCH, inc. Page 10