HomeMy WebLinkAboutMINUTES - 08122003 - C.33 TO: BOARD OF SUPERVISORS ell
FROM: MAURICE M. SHIU, PUBLIC WORKS DIRECTOR
DATE: August 12, 2003
SUBJECT: APPROVE and AUTHORIZE the Public Works Director, or designee, to execute a contract with
Bill Wigginton, Geolex, Inc., in the amount of$129,878, to Provide monitoring and maintenance
as General Manager for the Hillcrest Heights Geologic Hazard Abatement District, for the period
August 1, 2003 to July 31, 2005, El Sobrante area. (District I) Project No. 7756-6X5396
SPECIFIC REQUEST(S)OR RECOMMENDATION(S)&BACKGROUND AND JUSTIFICATION
I. Recommended Action:
APPROVE and AUTHORIZE the Public Works Director, or designee, to execute a contract with Bill
Wigginton, Geolex, Inc., in the amount of$129,878, to provide monitoring and maintenance as General
Manager for the Hillcrest Heights Geologic Hazard Abatement District (GHAD), for the period August
1, 2003 to July 31, 2005, El Sobrante area.
II. Fiscal Impact:
There is no impact to the County General Fund. The funding source for this service is derived from
revenues generated by the Hillcrest Heights Geologic Hazard Abatement District.
Continued on Attachment:X SIGNATURE:
_.t.,#+;ECOMMENDATION OF COUNTY ADMINIS OR
_RECOMMENDATION OF BOARD COMMIT'
,PROVE OTHER
SIGNATURE(S)
ACTION OF BO�Q ON AUG. 12, 2003 APPROVED AS RECOMMENDED Xx OTHER
VOTE OF SUPERVISORS
_x UNANIMOUS(ABSENT NO NF: )
AYES: NOES: I hereby certify that this is a true and correct copy
ABSENT: ABSTAIN: of an action taken and entered on the minutes of
the Board of Supervisors on the date shown.
MF:sr
G:\GrpData\SpDist\Board Orders\2003\08-12-03 BO-Hillcrest Heights GHAD.doc
Orig.Div:Public Works(Special Districts) ATTESTED: AUGUST 12, 2003
Contact: Skip Epperly(313-2253) JOHN SWEETEN,Clerk of the Board of
cc: County Administrator
Assessor Supervisors and County Administrator
Auditor-Controller
Community Development
County Counsel
B.Wigginton,Geolex,Inc. By ��'Deputy
Contract Folder
CHAD Folder&Binder
SUBJECT: APPROVE and AUTHORIZE the Public Works Director, or designee, to execute a contract with
Bill Wigginton, Geolex, Inc., in the amount of$129,878, to provide monitoring and maintenance
as General Manager for the Hillcrest Heights Geologic Hazard Abatement District, for the period
August 1, 2003 to July 31, 2005, E1 Sobrante area. (District I) Project No. 7756-6X5396
DATE: August 12, 2003
PAGE 2
III. Reasons for Recommendations and Background:
Bill Wigginton at Geolox, Inc. has been providing the monitoring and maintenance of the Hillcrest
Heights GRAD in the El Sobrante area for the past five years. The CHAD wishes to continue utilizing
this firm for these services.
IV. Consequences of Negative Action:
The monitoring and maintenance of the CHAD will be negatively impacted without execution of this
contract.
xd
CONSULTING SERVICES AGREEMENT
1, Special Conditions. These Special Conditions are incorporated below by reference.
(a) Public Agency: Public Works Department
(b) Consultant's Name &Address: William Wigginton,,906 Geolex �
POB 374
Aptos, CA 95001
(c) Project Name, Number, & Location: Hillcrest Heights CHAD, 7756-6X5396, El Sobrante Area
(d) Effective Date: August 1, 2003
(e) Payment Limit(s): $129,678.00($64,878.00 for 2003-2004 and$65,000.00 for 2004-2005)
(f) Completion Date(s): July 31, 2005
2. matures.These signatures attest the parties' agreement hereto:
PUBLIC AGENCY CONSULTANT
By: Maurice M. Shiu �, j 1 �►+'��f�`
Public Works Director/ By: Lam'
Chief Engineer, or Designee (Designate official cap in the b siness. Type of Business:
(sole proprietorship,government agency,partnership,corporation,etc.)
If Corporation, State of] corporation: CA
By. By: C !'<5 -000#AC ee,445 t `� ►
(Designate official coicity in thd business. Type of Business:
(sole proprietorship,t6vernment agency,partnership,corporation,etc.)
Note to Consultant: For corporations,the contract must be signed by two officers.The first signature must be that
of the chairman of the hoard, president, or vice-president; the second signature must be that of the secretary,
assistant secretary,chief financial officer,or assistant treasurer.(Civ.Cade,Seco 1190 and Corps.Code.Sec.313.)
The acknowledgment below must be signed by a Notary Public.
CERTIFICATE OF ACKNOWLEDGMENT
State of California
} ss.
County of }
Can the date written below,before me,the undersign otary Public onaily appeared the person(s)signing above for
Consultant, personally known to me (or proved to me o e of satisfactory evidence)to be the person(s)whose
name(s) is/are subscribed to the within instrument an ]edged to me that he/she/they executed the same in
his/her/their authorized capaeity(Ees), and that by N r/their sig re(s)on the instrument the person(s), or the entity
upon behalf of which the person(s)acted, ex ed the instrument.
WITNESS my hand and official se
Dated:
No ublic
(Notary's Seal)
CALIFORNIA ALL-PURPOSE ACKNOWLEDGMENT
State of California
ss.
County of -
On 0 IV 02M3 before me, t Q, _
Date oma and Titte of Oflicer�,.� "'lane Doe,Notary PubllC)
personally appeared ,_—W .. { 1� ._.._
Names)o!sign (s)
Cl personally known to me
proved to me on the basis of satisfactory
evidence
_ w.,,t�..:.. .. to be the person whose name i
LISA A.DALZIEL
Commission# 1377110 subscribed to the within instrument and
6MyComm.EVkesS9p28,2W61
Notary Public - California acknowledged to me thah Islaa executed
he~Contra Costa County the same in his heuthorized capacity(*t , and that bylot* .r
signator on the instrument the person or
the ent4 pon behalf of which the person(
acted, executed the instrument.
IT SS my hand a d i I sea
signature of Notafy-SWII
OPTIONAL
Though the information below is not required by law,it may prove valuable to persons relying on the document and could prevent
fraudulent removal and reattachment of this form to another document.
Des t ' iton of Attached Document
Title or Type o ocument:
Document Date: bet of Pages:..,..
Signers)Other Than Named Above:
Capacity(ies) Claimed by Signer
Signer's Name: ..
C7 Individual ; Top of tt:tmib here
0 Corporate Officer—Title(s):
0 Partner—El Limited F]G ral
Attorneyan-Fact
C. Trustee
❑ Guardian or C ervator
O Other:
Signe Representing:_ —�
11-
Q;999 National Notary Assoolation•9350 Da Soto Ave.,P.O.Box 2402•Chatsworth,CA 91313-2402•www.nationa;notaq.org Prod.No.$907 Reorder:Cali toil-Free 1-800-B7e-6827
CONSULTING SERVICES AGREEMENT
3. Parties. Effective on the above date,the above-named Public Agency and Consultant mutually agree and promise as
follows:
4. Employment,Public Agency hereby employs Consultant,and Consultant accepts such employment,to perform the
professional services described herein, upon the terms and in consideration of the payments stated herein.
5. Scope of Service.Scope of service shall be as described in Exhibit A&Exhibit C,attached hereto and made a part
hereof by this reference.
6. Report Disclosure Section.Any document or written report prepared hereunder by Consultant,or a subcontractor,for
Public Agency shall contain, in a separate section, the numbers and dollar amounts of this contract and all sub-
contracts relating to the preparation of such document or written report,provided that the payment limit specified in
Sec. 1(e) exceeds $5,000. When multiple documents or written reports are the subject or products of this
agreement,the disclosure section may also contain a statement indicating that the total contract amount represents
compensation for multiple documents or written reports.
7. Insurance.Consultant shall, at no cost to Public Agency,obtain and maintain during the term hereof:(a)Workers'
Compensation Insurance pursuant to state law; (b) Professional Liability Insurance with minimum coverage of
$1.000,000.00 and a maximum deductible of $50,000,00; and (c) Comprehensive General Liability Insurance,
including blanket contractual(or contractual liability)coverage,broad form property damage coverage,and coverage
for owned and non-owned vehicles, with a minimum combined single limit coverage of $1 000000.00 for all
damages due to bodily injury,sickness or disease,or death to any person, and damage to property, including the
loss of use thereof, arising out of each accident or occurrence, and naming Public Agency, Contra Costa County
Public Works Department its/their governing bodies officers and employees as additional insureds.Consultant shall
promptly furnish to Public Agency certificates of insurance evidencing such coverage and requiring 30 days'written
notice to Public Agency of policy lapse,cancellation or material change in coverage.
8. Payment. Public Agency shall pay Consultant for professional services performed at the rates shown in Exhibit B&D
attached hereto,which include all overhead and incidental expenses,for which no additional compensation shall be
allowed. Notwithstanding the foregoing, those incidental expenses specifically itemized in Exhibit S & D shall be
reimbursable by Public Agency to Consultant,provided that Consultant submits copies of receipts and,if applicable,
a detailed mileage log to Public Agency. In no event shall the total amount paid to Consultant exceed the payment
limit(s)specified in Sec. 1(e)without prior written approval of the Public Agency.Consultant's billing statements shall
be submitted at convenient intervals approved by Public Agency and shall list, for each item of services, the
employee categories,hours and rates.Public Agency will pay consultant in accordance with the requirements of Civil
Code Section 3320 as applicable.
9. Status.The Consultant is an independent contractor, and shall not be considered an employee of Public Agency.
10. Time for Completion.Unless the time is extended in writing by Public Agency,Consultant shall complete all services
covered by this Agreement no later than the Completion Date(s)listed above.
11. Record Retention and Auditing.Except for materials and records delivered to Public Agency,Consultant shalt retain
all materials and records prepared or obtained in the performance of this Agreement,including financial records,for
a period of at least five years after Consultant's receipt of the final payment under this Agreement.upon request by
Public Agency,at no additional charge,Consultant shall promptly make such records available to Public Agency,or
to authorized representatives of the state and federal governments,at a convenient location within Contra Costa
County designated by Public Agency, and without restriction or limitation on their use.
12. Documentation,Consultant shall prepare and deliver to Public Agency at no additional charge,the items described in
Appendix A to document the performance of this Agreement and shall furnish to Public Agency such information as
is necessary to enable Public Agency to monitor the performance of this Agreement.
13. Ownership of Documents.All materials and records of a finished nature,such as final plans,specifications,reports,
and maps, prepared or obtained in the performance of this Agreement, shall be delivered to and become the
property of Public Agency.All materials of a preliminary nature,such as survey notes,sketches,preliminary plans,
computations and other data,prepared or obtained in the performance of this Agreement,shall be made available,
upon request, to Public Agency at no additional charge and without restriction or limitation on their use.
CONSULTING SERVICES AGREEMENT
14. Extra Work. Any work or services in addition to the work or services described in Exhibit A&C shall be performed
by Consultant according to the rates or charges listed in Appendix B. In the event that no rate or charge is listed for a
particular type of extra work,Consultant shall be paid for the extra work at a rate to be mutually agreed on prior to
commencement of the extra work. In no event shall Consultant be entitled to compensation for extra work unless a
written authorization or change order describing the work and payment terms has been executed by Public Agency
prior to the commencement of the work.
15. Pavment Retention. Public Agency shall retain ten percent f, Q}of the monies due the Consultant as security for
the fulfillment of this Agreement.After the Consultant completed all work under this Agreement,submitted final
billing,and the Public Agency has found the wor a accurate,the Public Agency will pay all withheld funds.Public
Agency will pay withheld funds in accords w#th the requirements of Civil Code Section 3320 as applicable. A
retention will not be withheld for any"o SII°work.
16. Termination by Public Actency.At its option, Public Agency shall have the right to terminate this Agreement at any
time by written notice to Consultant,whether or not Consultant is then in default.Upon such termination,Consultant
shall,without delay,deliver to Public Agency all materials and records prepared or obtained in the performance of
this Agreement, and shall be paid,without duplication, all amounts due for the services rendered up to the date of
termination.
17. Abandonment by, Consultant. In the event the Consultant ceases performing services under this Agreement or
otherwise abandons the project prior to completing all of the services described in this Agreement,Consultant shall,
without delay, deliver to Public Agency all materials and records prepared or obtained in the performance of this
Agreement, and shall be paid for the reasonable value of the services performed up to the time of cessation or
abandonment, less a deduction for any damages or additional expenses which Public Agency incurs as a result of
such cessation or abandonment.
18. Breach. In the event that Consultant falls to perform any of the services described in this Agreement or otherwise
breaches this Agreement,Public Agency shall have the right to pursue all remedies provided by law or equity.Any
disputes relating to the performance of this Agreement shall not be subject to non judicial arbitration.Any litigation
involving this Agreement or relating to the work shall be brought in Contra Costa County, and Consultant hereby
waives the removal provisions of Code of Civil Procedure Section 394.
19. Compliance with Laws. In performing this Agreement, Consultant shall comply with all applicable laws, statutes,
ordinances,rules and regulations,whether federal,state,or local in origin.This includes compliance with prevailing
wage rates and their payment in accordance with California Labor Code,Section 1775,
20. Assignment. This Agreement shall not be assignable or transferable in whole or in part by Consultant, whether
voluntarily,by operation of law or otherwise;provided,however,that Consultant shall have the right to sub-contract
that portion of the services for which Consultant does not have the facilities to perform so long as Consultant notifies
Public Agency of such subcontracting prior to execution of this Agreement.Any other purported assignment,transfer
or sub-contracting shall be void.
21 Subcontracting. All subcontracts exceeding $25,000 in cost shall contain all of the required provisions of this
contract.Consultant will pay each subconsultant in accordance with the requirements of Civil Code Section 3321 as
applicable.
22. Endorsement on Plans. Consultant shall endorse all plans, specifications, estimates, reports and other items
described in Appendix A prior to delivering them to Public Agency, and where appropriate, indicate his/her
registration number.
23. Patents and Copyrights. The issuance of a patent or copyright to Consultant or any other person shall not affect
Public Agency's rights to the materials and records prepared or obtained in the performance of this Agreement.
Public Agency reserves a license to use such materials and records without restriction or limitation, and Public
Agency shall not be required to pay any additional fee or royalty for such materials or records.The license reserved
by Public Agency shall continue for a period of fifty years from the date of execution of this Agreement, unless
extended by operation of law or otherwise.
CONSULTING SERVICES AGREEMENT
24. Indemnification. Consultant shall indemnify,defend,save,protect,and hold harmless Public Agency,its governing
body,officers,employees,representatives,and agents("Indemnitees")from any and all demands, losses,claims,
casts, suits, liabilities, and expenses for any damage, injury, or death (collectively "Liability") arising directly or
indirectly from or connected with the services provided hereunder which is caused, or claimed or alleged to be
caused, in whole or in part, by the negligence or willful misconduct of Consultant, its officers, employees, agents,
contractors, subconsultants, or any persons under its direction or control and shall make good to and reimburse
Indemnitees for any expenditures, including reasonable attorneys'fees and costs, the Indemnitees may make by
reason of such matters and,if requested by any of the Indemnitees,shall defend any such suits at the sale cost and
expense of Consultant. Consultant's obligations under this section shall exist regardless of concurrent negligence or
willful misconduct on the part of the Public Agency or any other person;provided,however,that Consultant shall not
be required to indemnify Indemnitees for the proportion of liability a court determines is attributable to the negligence
or willful misconduct of the Public Agency, its governing body,officers, or employees. This indemnification clause
shall survive the termination or expiration of this Agreement.
25, Heirs,Successors and Assigns.Except as provided otherwise in Section 20 above,this Agreement shall inure to the
benefit of and bind the heirs, successors, executors, personal representatives, and assigns of the parties.
26. Public Endorsements. Consultant shall not in its capacity as a Consultant with Public Agency publicly endorse or
oppose the use of any particular brand name or commercial product without the prior approval of the Public Agency's
governing board. In its Public Agency Consultant capacity,Consultant shall not publicly attribute qualities or lack of
qualities to a particular brand name or commercial product in the absence of a well-established and widely accepted
scientific basis for such claims or without the prior approval of the Public Agency's governing board. In its Public
Agency Consultant capacity,Consultant shall not participate or appear in any commercially-produced advertisements
designed to promote a particular brand name or commercial product,even if Consultant is not publicly endorsing a
product, as long as the Consultant's presence in the advertisement can reasonably be interpreted as an
endorsement of the product by or on behalf of Public Agency. Notwithstanding the foregoing, Consultant may
express its views on products to other Consultants,the Public Agency's governing board,its officers,or others who
may be authorized by the Public Agency's governing board or by law to receive such views.
27. Project Personnel. In performing the services under this Agreement, Consultant shall use the personnel listed in
Exhibit D, attached hereto and made a part hereof by this reference. Changes in project personnel may only be
made with Public Agency's written consent, and Consultant shall notify Public Agency in writing at least thirty(30)
days in advance of any proposed change. Any person proposed as a replacement shall possess training,
experience and credentials comparable to those of the person being replaced.
28. Consultants must give consideration to DBE Firms as specificed in 23 CFR172 5fe)
Attachments:Exhibit A,Exhibit 8,Exhibit C,and Exhibit D
Form approved by County Counsel(5/00)
G:\GrpData\SpDistlContractN\GeolexHillcrestGHAD2003-2005
Exhibit A
A. 4n a periodic basis during each year, the GHAD will perform the following:
1. Monitoring and maintenance of the following items:
a) Interceptor Ditches
b) Piezometers and hydraugers
c) Survey points and benchmarks
d) Subdrains
2. Mitigation measures, including the following items:
a) Sandbagging
b) Hydroseeding
3. Cather items included within is the Plan of Control (Exhibit C)
S. During each year, the GHAD will perform repair and improvement projects as and
when necessary, within budgetary limits.
Exhibit B
Projected Revenue
Assessment
$ 983 per unit per year x 66 units (2003/2004)= $ 64,878
$1,006 per unit per year x 65 units (200412005)w $ 65,000
Projected Expenses Estimated Estimated
2003/2004 2004/2005
General Manager/Geologist ($150 per hour) $ 9,000 * $ 9,000
Support Services (Consultants) $ 7,500 * $ 7,500
Repair, Maintenance (see Appendix C) $ 20,200 * $20,700
Improvement Program — Cleaning $ 15,000* $ 5,000*
and capping subdrains
SUBTOTAL $ 51,700 * $ 42,2130*
Legal, Accounting and Insurance $ 8,000 $ 8,000
County Staff Services $ 0 $ 0
Reserve for contingencies $ 5,178 $ 14,800
TOTAL. NOT TO EXCEED $ 64,878 $ 65,000
* - These are payment limits for which the District Manager has authority to
pay. The Support Services and the Maintenance Contractors are paid by the
Contra Costa County based on District Manager and the Contra Costa
County's approval.
n
Exhibit C
"ILLCIt-]E T BEI HT
UBD. ION 7582
GEOLOGIC HAZARD ABATEMENT
DISTRICT (GRAD)
PLAN OF CONTROL
MONITORING & hUINTENANCL AlANUAL
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t� $
TABLE OF CONTENTS
Hillcrest Heights, Subdivision 7582
GHAD, Plan of Control
Letter of Transmittal
Recital 1
GHAD (Description) 2
Description of Landslide Hazard 2
Other Potential Geotechnical/Geologic Hazards 3
Exclusion of Isolated Problems on a Single Lot 4
PLAN OF CONTROL
A. Authority and Scope 5
B. Criteria for inclusion or Exclusion 5
C. Funding 6
D. Description of Geologic Hazards and Repair 7
E. Definitions 9
F. Plan for Prevention, Mitigation, Abatement, or Control 9
G. Geotechnical Techniques for Mitigation 9
H. Operation and Maintenance Procedures 10
I. Monitoring Frequency 13
J. Annual Report i3
K. Initial Start-up Period 14
L. Future Modifications of Plan of Control 14
FIGURES
1. Vicinity Map
2. Site Map
3. Rough Grading Plan
4. Schematic of Remedial Grading
5. Eastern Landslide Repair Cross-section
6. Western Landslide Repair Cross-section
7. Subdrain Detail
8. Preliminary Remedial Grading Plan
9. B-58 Concrete Lined Ditch
14. J Concrete Lined Ditch
GEOLOGIC AND SOILS MAP (Pre-Construction by Harlan Tait for EIR)
BIBLIOGRAPHY
Hl"LLCREST HEIGHTS SUBDIVISION 7582
GEOLOGIC HAZARD ABATEhWI TT DISTRICT
GHAD
Plan of Control and Monitoring and Maintenance Manual
RECITAL
The proposed project,Hillcrest Heights,is an R-6 single-family residential detached development.
(six units per acre) consisting of 66 lots on 17.5-± acres. The subdvision.is located within the
unincorporated El Sobrante.area of Contra Costa County on a north facing hillside of the San
Pablo Ridge (see Figures 1 & 2). Two open space parcels within the subdivision are the 2.65
acre Parcel B and 0.13 acre Parcel A. These parcels lie outside of individual lot boundaries, and
are to be under the ownership of the Hillcrest Heights Homeowners Association (HOA)together
with the HOA maintained private streets.
The project EIR recognized that a potential significant geologic hazard exists for this
development in the form of landslides. "elides on site need to be properly evaluated as to their
hazard potential to site. Sites near Hayward fault and its or any other nearby faults effects need .
to be evaluate(." Also since the site will be heavily graded this was considered a significant
environmental impact and "the effect on this on underground water needs to be investigated".
These issues raised in the EIR. were addressed in the geotechnical reports by Alan Kropp and
Associates (AKA 1988,1991,1995) and a geologic report by Darwin Myers Associates (1988).
Other relevant publications used in preparation of this report are in the Bibliography in the
Appendix. AKA came to the conclusion that'"the site is suitable for the proposed development."
This was with the provision that the conclusions and recommendations contained in their reports
were followed. Corrective work to stabilize landslide materials is defined in these reports.
Darwin Myers (1988) in his geologic report recognized the potential landslide hazard and stated
" a network of subdrains, in combination with--an efficient surface drainage system will be
critical to stabilize the site."
The County in its Conditions of Approval (6/13/93) for the Hillcrest Heights Subdivision,
recognizing a need for post-construction maintenance of surface and subsurface drainage
facilities, called for in Condition 21 (J).
"A Geologic Hazard Abatement District (GHAT)) or functional equivalent shall be developed to
monitor and maintain the slope stability measures (e.g., subdrains) for this development."
The Conditions of Approval place a requirement for an annual inspection report to be filed with
the County by "a licensed Geotechnical Engineer." The intent of the Condition of Approval
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rains, breaks in water lines, or other severe environmental conditions. For this reason the
G1 AD is responsible to make slope repairs that affect more than one property owner within the
district.
OTHER POTENTIAL GEOTLCHI\TICAL/GEOLOGIC HAZARDS
Reside landsliding, several other geotechnical and/or geologic hazards are described for this
project, including.
1. Erosion and sedimentation
2. Expansive soils and bedrock
3. Creep of slopes
4. Earthquake hazards such as ground shaking
5. Potential flooding
It is not the purpose of the Geologic Hazard Abatement District to take care of all potential soil
and geologic problems or concerns within the project site. potential landsliding is the primary
hazard for which the district serves as the mitigation measure. Rapid removal of surface water
resulting from precipitation by means of concrete lined ditches and storm drain facilities prevents
waterinfiltration into the subsurface and weakening of slope materials. 'Therefore proper
operation of the concrete lined ditches, storm drains and detention pond is considered a long-
term maintenance function suitable for the district. The surface ditches which total approximately
4,000 feet of aggregate length drain into a permanent stormdrain system. A sediment detention
basin six feet deep and 60 by 100 foot in dimension is also present on-site. An.erosion control
plan is required for this project and details for post-construction maintenance should be given
in this document.
The geotechnical report (AICA 1995) states that the surficial clay soils and landslide debris are
moderately to highly expansive and can undergo significant volume changes when shrinking and
swelling. finis can cause damage to homes, pavements, garage slabs, etc. Design mitigation
will include the use of drilled pier and grade beam foundations for homes. In the EIR the
authors also recognize the likelihood that the bedrock can also exhibit expansive (swelling)
characteristics. The Hillcrest Heights Geologic Hazard Abatement District is not formed to
undertake repairs resulting from the shrink-swell phenomena unless it directly effects the
integrity and functioning of the drainage facilities for which it is responsible.
Soil creep is.differentiated from landsliding in that landslides have a distinct surface of sliding
(slip plane), and creep does not. Creep may, however, in some cases be a precursor of
landsliding. The rate of movement for creep is in fractions of an inch per year whereas
landsliding occurs in inches or feet per day, month, or year. AKA(1995) state that "the surface
soils tend to lose strength after prolonged rains, and when they are located on moderate slopes
they have a tendency to creep". The mitigation measure chosen, given that the proposed homes
are to be constructed on sloping terrain, is to design the foundation elements to resist the
anticipated creep forces near the ground surface. The Hillcrest Heights CHAD is not firmed
3
' k
to undertake repairs resulting from the soil creep phenomena, unless it directly effects the
integrity and functioning of the drainage facilities for which it is responsible. AKA is expected
to place at least four slope inclinometers into the subsurface and periodic readings will be made
by the District to record the depth and amount of any ground.movement with time at the chosen
installation sites.
The Hillcrest Heights Subdivision is located approximately 0.7 to 1 mile northeast of the nearest
strands of the active Hayward fault. The assumption is made (AICA, 1995) that the site will be
subjected to at least one moderate to severe earthquake during the next 30 to 50 years. The
likelihood of fault offset at the site is considered remote,however, ground shaking would occur.
A secondary effect of earthquakes is seismically induced landsliding. The EIR authors under
mitigation measure 4.2-1(g) recognize this possibility and call. for: "A stability analysis of both
existing and reconstructed project area slopes should be performed. Project area slopes should
have a factor of safety greater than one under the effects of the design earthquake, ag ing
maximum pgssible growndwater levels during the life f the project" (underline added for
emphasis in this document).
A stability analysis (static and pseudostatic) was prepared by AKA. The maximum allowable
Level of groundwater is to be defined. Currently the stability analyses are based on an assumption
that groundwater would remain below the repaired material at the base of the compacted fill.
The CHAD monitoring responsibility is to assure that the ground water level in the subdrained
areas does not rise above the maximum possible groundwater level as'determined by the project
design.
Personnel retained by Hillcrest Heights GHAD are used to inspect surface drainage facilities,
concrete lined ditches, the inlets, subsurface storm drains, and the sediment detention basin. The
Hillcrest Heights GRAD is not formed to undertake repair of earthquake damage unless it
directly effects the integrity and functioning of the drainage facilities for which it is responsible.
EXCLUSION OF ISOLATED PROBLEMS ON A SINGLE,LOT
The Hillcrest Heights Geologic Hazard Abatement District(GHAD) is not intended to treat
landsliding or adverse erosion damage confined within a single lot boundary. If, however, a
hazardous landslide or erasion condition encroaches from a lot into the open space (Parcels A
or B) or crosses a property line, or threatens in the judgement of the District more than one
property the District should act to mitigate the damage.
4
HII.LLCREST HEIGHTS CHAD
PLAN OF CONTROL
Maintenance and Monitoring Manual
EXHIBIT C
A. Authority and Scone
Under authority of the California Public Resources Cade(Division 17, commencing with Section
26500) the County of Centra. Costa wishes to establish the Hzllerest Heights Geologic Hazard
Abatement District (CHAD) in the El Sobrante area. Development of the Plan of Control by
a state licensed Certified Engineering Geologist is a requirement for formation of a CHAD. The
potential for long-term landslide and erosion are known to exist and this plan document provides
a plan for their prevention, mitigation, abatement, or control.
B. r n lu i n or EXclUsi
Exclusions
1. Landslide or erosion damage within a single lot which does not pose a clear cut hazard
to public health, safety and welfare.
2. Maintenance of privately maintained right of ways other than the EVA.
3. Property or lot which lies completely outside the GHAT) boundary in which the landslide
or erosion problem does not encroach or directly affect the improved lands within the district.
4. Surface concrete lined drainage ditches or homeowner installed subdrains that traverse only
one lot.
C. Funding
The GRAD District will be funded from the assessment of each lot within the GHAD
boundaries. The tax assessment would commence upon the filing of the Final Subdivision Map.
The owner of each lot which includes the developer would pay the full assessment whether or
not a residence is constructed on the lot.
a. Single Family Unit(lot size up to 1 acre )....$-;$75--per Year*(approximate)
* Based on 1996 estimate. Automatic escalation according to US Dept. of Labor, Bureau
of Labor Statistics, Consumer Price Index.
Open space and undeveloped land within the district will not be assessed. Streets, the detention
basin, and any lands held in common by the homeowners association will not be assessed.
The project is anticipated to be graded in 1996 and lot sales would commence in 1997. For the
first year after grading the contractor is normally responsible for any defects or problems with
drainage installations. The developer is expected within the three year buildout period to handle
any minor landslide or erosion problems. It is therefore expected that a reserve can be
established in the first three years on the order of$60,000. The reserve should only be tapped
to repair shallow landslides or adverse erosion within the district areas of responsibility, to
maintain ditches, or repair damaged pipes for which the district is responsible.
6
F �
D. Description of Geologic Hoards and Repair
The site is on "a northwest facing slope that contains two swales. Elevations on the property
range from 340 feet near the southeast corner of the site to elevations of about 120 feet near the
northwest comer of the site. Natural slopes at the site are at inclinations of 2:1 (horizontal to
vertical) to 5:1 over broad areas "(AKA, 1995). The average slope is slightly steeper than 5:1,
ie 22°x. The majority of the site appears hummocky suggesting soil creep or shallow soil
slippage (AKA, 1995).
Beneath a soil cover of colluvium, landslide deposits, existing fill, or terrace deposits is the
bedrock of the Pliocene Contra Costa Group C'fce). This unit consists chiefly of a weakly
lithified nonmarine claystone, siltstone, sandstone, and pebble conglomerate. 'Where exposed
bedrock dips of approximately 35 to 40 degrees to the southwest. For more detail on site
geology refer to the geologic reports referenced in the Bibliography.
Harding Lawson and Associates (lU A, 1988) prepared the first site specific geologic map and
outlined two significant large landslide deposits (15 to 20 foot thick) on-site which have become
identified as the eastern slide and western slide. A smaller on-site active slide(northeastern slide)
is also mapped.
The Hillcrest Heights Subdivision 7582 Grading Plan was prepared by Wollman Associates and
is .included as Figure 3. A major portion of the site is to be graded with approximately a
balanced 100,000 cubic yards of cut and fill. Slope repairs could take an additional 110,000
cubic yards (Simonitch, 1992) Depth of cut is up to 26 feet and thickness of fill can be up to
32 feet.
The corrective work solution for the existing landslides by the project geotechnical consultant
AKA is to remove the landslide material. onsite. "Corrective work should include the
construction of a keyway at the downslope boundary of the work, construction of benches in the
slope where.material is to be placed, installation of subsurface drainage systems, placement and
compaction of the materials onto the preps slope, and construction of surface drainage
features" (AKA,1995), see Fig. 4. 'Two idealized cross-sections are presented in Figures 5 and
6 that show the regrading concept. They illustrate replacement of landslide debris with
compacted engineered fill. Figure 7 shows the detail of the subsurface drainage.installations at
the base of a subexcavated slope. During site grading some temporary shoring work will be
necessary along the southern property line to prevent upslope buildings from being adversely
affected by excavations necessary for the slope reconstruction work. Darwin Meyers (1988) in
his report for the landslides on-site recognized that"a network of subdrains, in combination with
an efficient surface drainage system will be a critically important component of any plans to
stabilize the site" (DMA, 1988). The primary function of the Hillcrest Heights CHAD is to
provide the post-construction long-term maintenance and monitoring of the subdrainage, surface
drainage, and buried storm drainage systems. Provided the drainage systems perform as designed
the landslide hazard is prevented, mitigated, or controlled.
7
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{joints glued where sloping>3.1). Provide g°':.; •i
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AS PER A. KROPP & ASSOCIATES ELT.S.
SUBDRAIN DETAIL. nom No.
C a E=- <=> L_.. E=- X SLMONISM 7582 7 EL SOBRANTI-, CALFORNA
.L W1G0x1N_T0N PROSECT HO. 95117 DATE A11.5,10A av xirn,ar
a
Subdrainage System
Figure 8 illustrates the current concept of the subdrainage system envisioned currently by the
project geotechnical consultant. Approximately 12,000 feet of piped subdrains are anticipated
by AKA ( see remedial grading plans dated Jan. 1996). It is expected that the project
geotechnical engineer will ultimately determine the extent and layout of the subdrains in the field
during grading. It is recommended by AKA that the project surveyor locate all subsurface
drains, solid pipes, and cleanouts on an AS-BUILT DRAWING OF REPAIR AREAS. These
drawings are definitely needed by the Hillcrest Heights CHAD to assist the district in locating
the pipes in the future.should any repair work be necessary.
Clean-outs for the subsurface drains are to be provided at the upslope boundary of each
subdrainage pipe and at intervals of no more than 100 feet for solid discharge pipe. Additionally
a cleanout should be provided at each 90 degree elbow. The collected water is taken to a
suitable "appropriate discharge facility".
Concrete Lined SurfaQe Drainage Ditches
Current grading plans show an aggregate length of 4,000 feet of concrete lined ditches of the
County B-58 and/or J design (see Figs. 9 & 10). B-58 ditches are typically placed on a 8 foot
width drainage terrace (see detail). AKA has called for no surface.water being allowed to flow
over the top of cut or fill, slopes. Drainage berms or interceptor ditches should be provided to
prevent surface water from flowing over the slopes. Drainage terraces on the surface of cut or
fill slopes should be provided with paved "V" ditches (in accordance with Contra Costa County
specifications for a B-58ditch). AKA calls for the use of reinforcing bars rather than wire mesh
in the concrete lining of the ditches. The ditches are to slope at a gradient of at least 5%.
Collected water is to be carried in solid pipe to an "appropriate discharge location": A cleanout
should be installed at the "high'" end of the solid pipe and at 100-foot intervals along the length
of the solid pipe. The project surveyor should survey in and place the location of this solid pipe
on the As-built drawing of the repair areas. Project Improvement Plans,should designate the
discharge storm drain facilities that the Hillcrest Heights GRAD is not responsible to maintain.
The EIR describes that a LEGAL ENTITY" ( which is in this case is the Hillcrest Heights
Geologic Hazard Abatement District) should be established to fund the needed maintenance of
concrete lined ditches, inlets or drainage pipes located on slope benches or along rear lot lines
in accordance with Division 914 of Title 9, Subdivision Ordinance. All drainage facilities that
drain more than one lot before entering the storm drain system. would be maintained by the
district. Drainage facilities that drain more than one lot located within lot boundaries need to
have specified easements to permit the district to enter to perform the needed maintenance.
Early implementation of the district is facilitated by developer funding in the form of assessment
on improved lots before homeowner occupancy. This together with the periodic inspection called
8
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3' min. WS 3' min.
12' v; ,ham 6' Lip -can uphill side
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6x6x10 Ga. mesh*
NOTE. Use rebvr, see 12' min.
comment below
C.C. CO. STD. B-58 DITCH
Lined surface ditch, sloping 5% minimum to suitable discharge facilities.
Lined ditches should be reinforced with reinforcing bars. (not wire mesh)
and have score joints spaced appropriately.
8 feet minimum
% minimum
DRAINAGE TERRACE DETAIL
KT.S.
B-58CONCRETE LINE DITCH DETAIL AND DRAINAGE TERRACE rWWK ko.
L._ E—= X SUBOMSION 7682
ttv c F c t p. f` 1 EL SCERANTF, CALIFURNA
V+1.B. W100INTON PROJECT NO. 95117 DATE 4/15196 RY WRW
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TYPICAL. `J` CONCRETE LINED DITCH ncURE No.
L Ev X SUBDMSION 7582 1�J
�r�tcCa t��Rsa.'r r� EL SOBRAt� CALFOFMA
W.E3. WI(:.GINT0N Sao tc xo. )5#17 oars 4/15/86 9Y WBW
for in this manual should provide adequate "proof that periodic maintenance" will be done. The
maintenance should reduce the impact of long-term erasion and sedimentation on-site. Required
monitoring should determine that the groundwater levels are maintained below a critical level
where slope stability could be,jeopardized.
B. pg initi n
LANDS IIlr1B - is defined as a deposit of soil and/or rock moving downward from
its original position under the influence of gravity. Slides are mass movements of earth
materials, primarily intact, which occur along discrete shear surfaces. These surfaces (shear or
slip planes) can be rotational such as for earth stumps, or planar as for translational earth slides
or block glides. Flows are mass movements of earth materials in which the type of movement
is one of flowing. When composed of soil finer than gravel size, the flowing material is
commonly called a mudflow. When the material flows downslope with speed the mass movement
is called a debris flow or avalanche.
MOSIDN - is defined as the process by which, earth materials are loosened and
removed by running water on the surface or in the subsurface. Sedirne ntation is the depositing
or settling of soil or rock particles from a state of suspension in a liquid.
T. Pign fQr PrP,van i i ti n A atement r on fExi tin r o anti Landslid
and Erosion Hazards
The district will retain'a professional registered geotechnical/civil engineer and/or a certified
engineering geologist to identify potential landslide and erosion. hazards. The professional
consultant or consultants or their staff shall monitor existing or potential. slide and erasion
hazards and take action if authorized by the GHAD Board of Directors to repair or stabilize
slides; and to mitigate,abate, or control the effects of sliding. The erosion hazard and adverse
sedimentation effects are also to be monitored, mitigated and controlled. The ongoing annual
maintenance is to be limited to that designated in the annual budget.
G. technical TechniQue._s for Midgation o LMdslide and Er _ionds
If a hazardous landslide or erasion condition affects more than a single property, one of which
is within District boundaries, or threatens in the judgement of the District more than one;
property, the Flan of Control is to be followed to mitigate the damage. This can include but may
not be limited to:
a. removal of the geologic hazard.
9
b. stabilization (either partial or total) of landslide by removal and replacement with
compacted drained fill.
C. construction of structures to retain or divert slide material: or sediment.
d. construction of erosion control devices such as gabions, riprap, gotextiles, or lined
ditches.
e. placement of drained engineered buttress fill.
L placement of subsurface drainage devices; e.g. underdrains, or horizontal drilled drains.
g. slope correction (i.e. gradient change, biotechnical stabilization, slope trimming or
contouring).
h. construction of additional surface ditches and/or detention basins, silt fences, sediment
traps, backfill or erosion channels.
Potential landslide and erosion hazards can best be mitigated by controlling soil saturation and
water runoff by maintaining the surface and subsurface drainage system. Operation and
maintenance procedures for district operation are given along with a proposed monitoring
schedule in the following sections.
H. ra ion and Mai:n�enance pr c uses
Once formed the Hillcrest Heights Geologic Hazard Abatement District through its retained .
professional consultant, would be responsible for implementation of the monitoring and
maintenance program. The Consultant retained-by the District could either be a Registered
Geotechnical/Civil:.Engineer or Certified Engineering Geologist with experience in landslides
and erosion and capable of maintaining civil engineering works. The administration required
is limited and can be done by the subcontracted private consultant. Funding initially is from
assessment of the lots (primarily developer's money in the beginning) and as the lots are sold
the individual homeowners tax assessment would fund the district's annual. budget.
Concrete Lined Ditches
The retained professional consultant and/or the consultant's designated representative would
make the recommended periodic inspections (see next section for monitoring frequency). This
10
to placement of inclinometers behind and upslope of these structures to monitor the slope along
the property line during grading. Provided the sharing materials are durable materials it is
appropriate to leave this shoring material in-place rather than pulling the shoring out as fill: is
placed. This would be up to the project geotechnical consultant to determine. If the inclinometer
casings upslope of the temporary sharing wall are left in place and are accessible, these
installations should be integrated into the CHAD monitoring network.
&Wring Nall Subdrainage
Some proposed retaining walls cross a number of property lines or are in open space. These
most likely would have a subdrainage system.planned behind as wall and possibly a concrete
lined ditch running behind the top of wall. The grading plan calls for criblock walls which are
concrete crib type structures. If a retaining wall is confined to one lot it is the responsibility of
the homeowner. If a wall, has a subdrain which crosses a number of lots or is in open space,
it is the district's responsibility to maintain the wall and to keep the drain functioning.
Adequate drainage may be
provided by a subdrain system consisting of 4-inch rigid perforated pipe bedded in 1/4-inch clean,
open-graded rock. The entire rock/pipe unit should be wrapped in an approved non-woven, polyester
geotextile. The rock and fabric placed behind the wall should be at Ieast one font in width and should
extend to within one.foot of finished grade. The upper one foot of backfill should consist of on-site,
compacted, relatively impervious soils(an impermeable plug). We should note that flexible, perforated
pipe(flexbe), 2000-Pound Mush, L,eachfteld, and ASTM FS 10 pipe are not acceptable for use in the
subdrain because of the likelihood of damage to the pipe during installation and the difficulty of future
cleaning with mechanical equipment without damaging the pipe. We.recommend the use of Schedule
40 PVC, SDR 35 PVC or ABS, Contech A-2000 PVC drainpipe, or equivalent for the drain system.
The subdrain pipe should be connected to a system of closed pipes(non-perforated) that lead to suitable
discharge facilities. At.the location where the perforated subdrain pipe connects with the solid discharge
drainpipe, drainrock backfill should be discontinued. A"clay plug" should be constructed out of relatively
impervious soils to direct and collected water into the perforated pipe and minimize the potential of water
collecting around the solid drainpipe and saturating the adjacent sails.
In addition, the "high" end and all 90 degree bends of the subdrain pipe should be connected to a riser
which extends to the surface and acts as a cleanout. The number of cleanouts can be reduced by installing
"sweep" 90-degree bends or pairs of 45-degree beads in succession instead of using "tight" 90-degree
bends. "Sweep" 90-degree bends are similar to those used in sanitary sewer pipe connections.
.Dined surface ditches should be provided behind any walls that will have an exposed sloping surface steeper
than 4:1 behind thefn. These ditches, which will collect runofl`water from the slopes, should be sloped
to drain to suitable discharge facilities. The trip of the walls should extend at least one foot above the
ditch(one foot of freeboard).
12
f ,
Deflection or Impact Structure
The EIR authors as a mitigation measure discuss the need of impact and deflection structures
below the Parcel B at the rear of Lots 35 and 36. Current grading plans show upslope retaining
walls behind Lots 38,39, and 40. An Emergency Vehicle Access Road and concrete lined ditches
are present on this slope upslope of the lots. The possibility of a debris flow is the reason for
the need of deflection or impact structures to protect downhill lots. If the graded slope is steeper
than 3:1 the possibility of more rapid debris flow movements is increased. The potentialbuildup
of slide debris against the upslope side of the wall as well as possible encroachment of slide
debris on the uphill ditches or EVA should be checked after heavy storms.
1. Monitoring Frequency
SURFACE(B-58/J)DITCHES and solid pipe outfalls....................................Semi-annually
SUBSURFACEDR.AINS in LandslideRepair Areas......................................Semi-ennually
SUBSURFACE DRAINS behind Common Retaining Walls...........................Annually
SLOPE INDICATORS..........................................................................5years*
*first set after one year and then every 5 Years.
DEBRIS ORIMPACTWALL......................................................................Annually
As a minimum two permanent piezometers should be placed by the Project Geotechnical
Consultant, one in the Eastern and one in the Western Landslide Repairs. 'Preferably these
should be placed in proximity to the two inclinometers in readily.accessible locations. Initial
readings of ground water level should be taken after completion of grading. and then Red Flag
Levels should be established by the project geotechnical engineer. At Red Flag Level 1 a
Licensed Geotechnical Engineer should be consulted to determine what if any remedial measures
should be undertaken. At Red Flag Level 2 the district should take some action to lower the
ground water such as by pumping or installing horizontal drains. Monitoring frequency should
be increased should a Red Flag water level be reached. Inclinometers 'should be placed in
grouted holes. If in excess of 2 inches of movement takes place or if the rate of movement is
in excess of 1 inch per year, monitoring frequency should be increased and a Licensed
Geotechnical Engineer consulted as to the significance of these measurements.
For annual inspections, the timing should preferably be in the spring, following the end of
winter rainfall. For semi-annual monitoring, the inspection should include a fall pre-winter storm
inspection and one in the spring following winter rains. For major (once every 5 year type)
storms that occur subsequent to 10 inches of rainfall within one winter season, a storm damage
check of the site would be appropriate by a district representative.
J. Annual RepQrl
An Annual Report shall be prepared by the Professional Registered or Certified Consultant
13
retained to administer the District. The scope of the work in preparation of the annual report
would be to:
a.) Prepare annual assessment roll.
b.) .Prepare a Quarterly financial report.
c.) Coordinate with the Hillcrest Heights Homeowners Association President or appropriate
Board Member so as to obtain maintenance plans of the association.
d.) Review monthly expense records for district.
e.) Calculate the level of taxation for the coming year.
The Annual Report and proposed budget for the Fiscal Year is to be submitted to the County
Board of Supervisors.
K. Initial Startup Period
The project is anticipated to be graded in 1995 and lot sales would commence in 1997. It is
expected that all lets would be sold in 3 years. The tax assessment would commence after the
filing of the Final Subdivision Map. The owner of each lot would pay the full assessment
whether or not a home is constructed on the lot. For the first year after grading the contractor
is normally responsible for any defects or problems with the drainage installations. The
developer is expected to handle any minor landslide problems during the 3 year buildout. The
first three years should permit a buildup of a reserve. Assuming an assessment per unit(lot) of
approximately$875 per year the annual initial budget is'on the order of$57,750. Provided that
$20,000 goes to a Reserve, $37,750 is the first year budget for administration and normal
maintenance. This is in 1996 dollars and a 6% inflation rate can be assumed for subsequent
years.
After 3 years a reserve of $60,000 could be established. The reserve should only be used to
repair shallow landslides or adverse erosion within the areas of district responsibility, to replace
ditches, or repair damaged pipes for which the district is responsible.
L. Future Modifications of Plan Of Control
This document is to be considered as the initial Plan of Control to serve as a guide for the
operation of the district. With time it may become necessary to update or expand this plan to
meet changed conditions present at some point in the future. The current document was prepared
based on available information from the project consultants (see Bibliography). No independent
study of the site conditions was made by William B. Wigginton, CBCT or GEOLEX Inc. and the
document was prepared for the sole use of the client Eugene Lee and the Hillcrest .Heights
CHAD.
14
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BIBLIOGRAPHY
1. Alan Kropp and Associates, 5/21/91, Geotechnical Evaluation Update (Appendix C of
4/28/95 report).
2. Alan Kropp and Associates, 4/28/95, Geotechnical Investigation, Hillcrest Heights.
3. Alan Kropp and Associates, 1/19/96, Supplemental Geotechnical Analysis, Hillcrest
Heights.
4. Alan Kropp and Associates, 3/20/96, Response to 3rd Party Review, Hillcrest
Heights.
5. Contra Costa County, 10/92, Draft Enviornmental Impact Report, Hillcrest Heights.
6. Contra Costa County, 3/93, Response to Comments on EIR.
7. Margason, E. M., 1984, Landslide Repair in Orinda Claystone Utilizing Geogrid
Reinforcement, International Symposium of Landslides, ISSMPE, Toronto, Volume 1
(Hillcrest Road Slide Repair).
8. McCutcheon, Doyle, Brown and Enerson, 1996, Draft Articles of Incorporation and
CC&R's, Hillcrest HOA:
9. Dyers, Darwin, 11/15/88, Subsurface Investigation, Hillcrest Heights.
10. Wollman Associates, 9/94, Grading Plan, Hillcrest Heights.
11. Wollman Associates, 2/96, Improvement Plans, Hillcrest heights.
12. Wollman Associates, 1/961, Preliminary Remedial Grading Plan, Hillcrest Heights.
Exhibit D
FEE SCHEDULE
Professional Services
William Wigginton -- principal Engineering Geologist $ 150 / hour
Depositions, Mediation and Court Appearances $ 750 Y2 day
$ 1,500 full day
Expenses
Hourly rates include all direct costs for photocopies, reproductions, postage,
courier services, facsimiles and telephones.
Travel
Hourly rates include all direct costs for personal safety gear, cellular telephone
and travel expenses. The rates shall also apply to travel time to and from site.
Auto mileage charged at applicable County rate.
Invoice
Invoice Monthly