san francisco district office ~~ p- i...

ST/\TI: (" (ALIF'0Fi'l'11A--·TH( Pf'SQlH~CES. AC.ENCY .• -·· ;_<.., ·-·-·- -==-=-~

DE:PAi\TMENT 01- CONS.CRVATION

DIVISION OF MINES AND GEOLOGY SAN FRANCISCO DISTRICT OFFICE FERRY BUILDING

SAN FRANCISCO. CA 94111 (Phon~ -'1~7·0633)

(415) 557-0413 ~~ P-, I

Robert W. Brown Acting Chief Building Official City of Fremont City Government Building Fremont, CA 94538

Dear Mr. Brown:

.. , . j.

I t -······'···3 ,... ···.··.· .. ···.··.·.··. -7··""'·.··.···. · ..• ....... ··. .··

·-August 24, 1982

we are placing on open file thee folle>wing reports, reviewed and approved by th" City of Fremont in compliance with the Alquist-Prio lo Specia 1 Studies Zones Act:

Seismic hazard report, Sierra del Lago, Fremont, CA; by Engeo, Inc.; February 11, 1982.

Geotechnical report, Fremont Station Project, Tyson Lane, Fremont, CA; by Earth Systems Consultants; November 20, 1981.

EWH: lg

cc: A-P file (2)~

Sincerely yours;

c;ti!Jk EARL w. HART Office of the State Geologist CEG 935

_:,,:· 'i' 1,;,,:~~·1 '

City of Fremont City Government Building Fremont, California 94538

State Division of Mines and Geology Room 1009, Ferry Building San Francisco CA 94111

•-·I ~ . .1

August 17, 1982

Attention: Earl W. Hart, Office of the State Geologist

RE: Geotechnical Report, Fremont Station Project, Tyson Lane, Fremont.

Gentlemen:

Enclosed for your files are the above report prepared for Maslesa Development, dated November 20, 1981, and the review by our consultant, Edward A. Danehy, Alameda County Engineering Geologist, dated August 8, 1982.

jl

encls.

cc: The Environmental Center

Very truly yours,

ROBERT W. BROWN Acting Chief Building Official (415) 791-4133

City of Fremont

. ' CO\Jl\;TY OF ALAMEDA .

PUBLIC WORKS AGENCY

ALA\JEJ)A COl'J\:'l'Y FLOOD CO.'>:'l'HOL ,\;\'Ll

WA'l'EH l'ONSERVATlON DIS'l'H1C'T

399 Elmhurst Street • Hayward, CA 94544-1395 • 1415) 881-6470

August 8, lg82

City Government Building P.O. Box 5006 Fremont, CA 94538

Attention: Robert W. Brown, Acting Chief Building Official

Gentlemen:

RE: FREMONT STATION PROJECT GEOTECHNICAL REPORT

As requested by the City of Fremont, the subject report prepared by Earth Systems Consultants on November 20, 1981 has been reviewed by me for conformance with the provisions of the Alquist-Priolo Special Studies Zones Act. This review only included the geologic aspects of the site and not soil

.or foundation engineering recommendations within the report. However, it should be noted that the site is very close to an active trace of the Hayward fault. Therefore, the effects of severe ground shaking should be adequately mitigated in the p 1 ans for site and building design.

This review consisted of examining the subject report, other reports on nearby properties and a reconnaissance of the site. A telephone conversation was held with Philip V. Burkland regarding details and clarifications. This included some drafting errors on the log of trenches (Figures B-1 and B-2.). Figure A-1 does not include several previous geologic investigations between those shown northwest of the site. Also, Figure A-1 should have used the 1980 edition of the official Special Studies Zones map (instead the 1974 version is shown) which depicts the fault location similar to the discussion in the text of the subject report.

City of Fremont August 8, 1982 Page Two

., . .

topographic depression in the southwest corner of the site". It is important that this zone be shown on the final tract map or other recorded document for the subject parcel.

It is my professional op1n1on that the subject report provides satisfactory compliance with the provisions of the Alquist-Priolo Act. A copy of this letter and the subject report should be submitted to the California Division of Mines and Geology, San Francisco, attention Earl Hart. Charges for this review have been made against the trust account established for that purpose. Should there be any questions, please contact me.

Edward.A. Danehy Registered Geologist No. 20 Certified Engineering Geologist No. 8

EAD:et

I I I I_

~· •-

GEOTECHNICAL REPORT

FREMONT STATION PROJECT

I Tyson Lane, Fremont, California

I I I I_ Prepared for

I MASLESA DEVELOPMENT

Campbell, California

I I I I I

By

EARTH SYSTEMS CONSULTANTS 1900 Embarcadero Road

I Palo Alto, California

NOVEMBER 1981

I

I I I I I I I I I I I I I I I I I I I

GEOTECHNICAL ENGINEERING • ENGINHRING GEOLOGY • ENVIRONMENTAL GEOLOGY

File No. Cl-1088-Cl November 20, 1981

Maslesa Development 1901 South Bascom Avenue Suite 1420 Campbell, California 95008

Attention: Mr. Michael A. Perata

Subject: Proposed Fremont Station Project Tyson Lane, Fremont, California GEDTECHNICAL REPORT

Gentlemen:

We are pleased to transmit the attached geotechnical report for the proposed Fremont Station condominium project, located on Tyson Lane, Fremont, California.

As indicated in the report, the approximately 6-acre site is considered suitable for the proposed residential development, provided the recommendations of this report are implemented.

If there are any questions regarding the contents of the report, please contact our office.

Very truly yours,

EAR~~H SYSTEMj CONSU,L TAN.TS .. , ,./J .. "1 J '/ ;l~-- /( .

fi_,,,_,.,71' .1 ·- t:r1~*--' I!" -----zi-

P h il i p 1i/. Burkland, C.E.G. 513

~~ Albert C. Gribaldo, C.E. 8412

tm

Copies: 3 to Maslesa Development 7 to The Environmental Center 1 to Hedley & Stark l to PRC Toups

1900 Embarcadero Road • Suite 200 • Palo Alto • California • 94303 • (415) 856•6750

I File No. Cl-1088-Cl

I November 20, 1981

I CONTENTS Page

I LETTER OF TRANSMITTAL

I GEOTECHNICAL REPORT - FREMONT STATION

I INTRODUCTION

I Purpose and Scope 1 Location and Description of Site 2 Figure l - Location Map 3 Proposed Development 5

I Geologic Setting 5

I EXPLORATORY PROCEDURES AND RESULTS

Trenching 8 Drilling and Sampling 9

I Laboratory Testing 11

I GEOTECHNICAL EVALUATION AND DISCUSSION

Soil Conditions 13 Groundwater 14

I Seismic Hazards 15

I CONCLUSIONS AND RECOMMENDATIONS

General 20

I Grading and Site Preparation 22 Foundations 24 Lateral Resistance 25 Retaining Walls 25 .-. Slab-on-Grade Construction 27 Utility Trenches 27 Surface Drainage 28

I Plan Review 28 Observation and Testing 28

I LIMITATIONS AND UNIFORMITY OF CONDITIONS 30

I ( i i )

I



CONTENTS - Continued

APPENDIX A

Literature and Map Review Figure A-1 Figure A-2 Aerial Photograph Interpretation Bibliography

APPENDIX B

Logs of Trenches Logs of Test Borings Summary of Laboratory Test Results Plasticity Chart Consolidation Curve Grain-Size Distribution Curves

APPENDIX C

Suggested Grading Specifications

PLATE l - Site Plan

( i i i )

Page

A-1 A-3 A-4 A-9 A-12

B-1 B-3 B-17 B-19 B-20 B-21

C-1

inside back cover

I I I I I I I I I I I I I I I I I

•• I


GEOTECHNICAL REPORT - FREMONT STATION

INTRODUCTION

Purpose and Scope

As indicated in our Work Order dated October 1, 1981, the purposes of this

geotechnical study were to: 1) explore and evaluate the geologic and seismic

hazard potential at the site of the proposed Fremont Station project; and 2)

·explore and evaluate the surface and subsurface soil conditions in relation to

the proposed site development. Based on the geotechnical conditions revealed by

the exploration and testing program, data evaluation and analysis,

recommendations have been prepared to mitigate the identified soil and geologic

factors. In addition, the report contains recommendations for use by the design

consultants in preparing site grading and foundation p 1 ans for the proposed

three-story residential structures.

The scope of the work performed for this study included:

1. Review and evaluation of published geotechnical reports and maps relating to the site vicinity;

2. Geotechnical reconnaissance of the site and surrounding area;

3. Interpretation and evaluation of stereo aerial photographs of the site area;

4. Subsurface exploration, consisting of twelve borings and three backhoe trenches;

5. Field and laboratory testing of representative soil samples obtained from the borings;

6. Evaluation and analysis of the data in relation to the proposed site use;

-1-



7. Discussions of preliminary findings with the developer, the project civil engineer and the project architect; and

8. Preparation of this report.

The scope of the geologic and seismic hazards evaluation was planned to comply

with the guidelines for reports for projects located in Alquist-Priolo Special

Studies Zones. The soil conditions were evaluated in relation to the residential

development shown on the preliminary plans and verbal information furnished by

the architect, civil engineer and developer. This information is described under

the heading "Proposed Development" on page 5.

Location and Description of Site

The area covered by this report consists of approximately 6.1 (±) acres of

undeveloped land located on the westerly side of Tyson Lane, approximately 117

feet south of its intersection with Greenwich Circle in Fremont, Alameda County,

California (see Figure 1, page 3). The nearly rectangular parcel is bounded on

the north by an existing residential subdivision (Tract 3778), on the east by

Tyson Lane, on the south by undeveloped property (Lands of Wang, et. al.), on the

southwest by Lands of Alameda County Flood Control and Conservation District, and

on the west by Lands of San Francisco Bay Area Rapid Transit (BART).

The site slopes gently to the southwest, ranging in elevation from approximately

62 along Tyson Lane to approximately 52 in the southwest corner. Most of the

site slopes to the west at a gradient of 1% or less. The westerly 150 feet (±) of

the site slopes down at approximately 5% to a linear depression along the

westerly boundary. This depression drains into an open pond, identified

-2-


APPROXIMATE SCALE IN MILES

LOCATION MAP

Fremont Station Project Fremont, California

-3-

Figure 1



as Tyson's Lagoon or "Tu le Pond", located adjacent to the

southwest corner of the site. The ground slopes up to higher elevations on the

BART property, west of the site. Boundary and topographic informatiorr are based

on a reconnaissance of the site and a drawing entitled "Boundary and Topographic

Survey, Tyson Lane, Fremont, California", Sheet l of 1, by PRC Toups, dated

8-25-81, at a scale of l" ~ 40'. That drawing was reduced and used as a base for

the Site Plan, Plate l, enclosed inside the back cover of this report.

The site is presently being used for agricultural purposes. An orchard covers

most of the southern portion of the property, whereas a recently disced field

covers most of the northern portion of the site. An existing house and

appurtenent structures are located in the northeast corner, with a barn located

in the southeast corner of the property. Access to the property and the existing

buildings is from the adjacent partially improved Tyson Lane. Other features on

or near the site include a dirt road which makes a turn across the southwest

corner of the property, and a storm drain pipe and headwall located just west of

the westerly property line. The flow line elevation of the 30-inch storm drain

pipe· is 46.8 (per plan by PRC Toups). The pipe appears to carry storm drainage

from the properties to the north and discharge it into the pond southwest of the

site. At the time of the field exploration, the water surface in the pond was

estimated to be at approximately elevation 47. A 10-foot wide easement for the

Sunset Telephone and Telegraph is shown on the plan by PRC Toups at the westerly

end of the property. It is not known whether any underground facilities exist

within the easement, but none were reported by "Underground Systems Alert" or

PG&E. An exploratory trench cut across the easement exposed no evidence for

-4-



underground utilities (at the trench location) within approximately 10 feet of

the existing ground surface. No underground irrigation lines, septic tanks or

other buried structures were evident at the time the work was done for this

report. It is expected however, that such facilities will be found at the site

during the clearing and grading operations. At least one water well is present

at the site near the existing residence. Others may be encountered elsewhere at

the site.

Proposed Development

The project is identified as Fremont Station on a "Preliminary Review Plan",

prepared by the Environmental Center, dated September 2, 1981. That plan

indicates that 208 condominium units will be constructed in eight building

clusters. Each cluster will consist of two rectangular buildings (approximately

12Dx45 feet each), separated by landscape and courtyard features. The

approximate outlines of the eight building clusters are shown on Plate 1.

Information supplied by Hedley & Stark, the project architect, and the

preliminary plan, indicate that each building will contain a lower level parking

garage, depressed approximately 2 feet below existing grade, and three levels of

living space above the garage area. The floor for the first level over the

garage will be post-tensioned concrete, with the upper levels planned as wood

frame construction. Column spacing in the garage areas will be on the order of

27 feet. Building loads were not available at the time this report was prepared.

Preliminary analyses were made for assumed column loads ranging from 100 to 400

kips, and wall loads ranging from 4 to 8 kips per lineal foot.

-5-



Other improvements will include the widening of the Tyson Lane frontage, a

central driveway/parking area, and recreation facilities in the central portion

of the project. Grading is proposed to be a balanced operation with the

materials excavated from beneath the buildings placed as fill and/or landscape

mounding outside the building areas.

Geologic Setting

The site is located at the northeastern edge of the southern Alameda section of

the San Francisco Bay Plain in the Coast Range Geomorphic Province of Central

California. The western foothills of the Hamilton-Diablo Mountain Range rise

from the plain approximately l mile east of the site.

The bedrock at depth, in this area, is the Franciscan Formation of upper Jurassic

to Cretaceous age (65 to 140 million years old). These rocks are part of a

northwest-trending belt of Cretaceous material that lies along the eastern side

of the San Andreas Fault zone, located approximately 18 miles southwest of the

site. The Franciscan rocks are overlain, in the site vicinity, by thick (several

hundred feet) deposits of Tertiary marine and non-marine sediments and by

Pleistocene to recent alluvial deposits.

The Hayward Fault has been mapped on or immediately west of the site. The fault

has been zoned by the California Division of Mines and Geology under the

provisions of the Alquist-Priolo Special Studies Zone Act of 1972. Because of

the proximity to the Hayward Fault, the site lies within a Special Studies Zone

as shown on the Niles Quadrangle (California Division of Mines and Geology,

1974). Further discussion of the geologic conditions affecting the site and

-.6-



surrounding area, based on a review of pertinent maps and reports and an

evaluation of stereo aerial photographs, is presented in Appendix A.

-7-



EXPLORATORY PROCEDURES ANO RESULTS

Trenching

Three trenches (T-1, T-2 and T-3) were excavated on and i111nediately west of the

site on October 5, 1981. A track-mounted backhoe was used, and the sidewalls

were supported with hydraulic shoring. The trenches were 24 inches wide, from 4

to 12 feet deep, and totalled 233 lineal feet. The walls were cleaned manually

and detailed logs were made of the materials exposed. Graphic representations of

the field logs are shown on Figures B-1 and B-2 in Appendix B. The trenches were

placed to intersect and be perpendicular to mapped fault traces in the area. The

locations of Trenches T-2 and T-3 were surveyed by PRC Toups and transferred to

P 1 ate 1. The location of Trench T-1 as shown on Pl ate l is based on taped

dimensions as measured from Trench T-2 and the surveyed storm drain headwall.

Trench T-1 was located just west of the southwest corner of the site. The

materials exposed consisted of from 3 to 8 feet of fill, which became thicker to

the east. The fill materials are underlain by silty clay and clayey fine sand.

The sediments below the fill have been offset both laterally and vertically along

a fracture near the center of the trench. This fracture is oriented (strikes)

N35°W and is inclined (dips) 73°E. It is interpreted to be an active trace of the

Hayward Fault. The fault or fracture is filled with fine silty sand. Its

structure, and the relationship to the surrounding sediments suggest that

1 iquefaction of some saturated loose sand body occurred during a previous

undefined earthqake. The liquefied sand apparently migrated along this fracture

and vented as a sand boil near the surface.

-8-



Trench T-2 was also located in the southwestern part of the site, extending about

25 feet west of the western property line. Fill similar to that found in Trench

T-1 was encountered at the western end of this trench. It was found to be about 5

feet thick at the western end, gradually decreasing in thicnkess to the east.

The fill overlies near horizontal layers of silty clay, clayey silt and clayey

fine sand. There was no evidence of faulting seen in this trench. Seepage was

encountered near the western end of the trench at approximately 8 to 10 feet

below the surface. This was the only free water observed in the three trenches.

Trench T-3 was located immediately west of the site, near the northwest corner of

the site. Flat-lying layers of silty clay were exposed, which have been deformed

along a fault plane near the western end of the trench. This fault trace is

inclined approximately 23°NE and is marked by a thin layer of clayey sand. The

presence of a layer of sandy sediment parallel to the fault may be indicative of

past sand boil or lurch cracking activity in this area. This fault shows

evidence of both vertical and lateral movement, and is probably a continuation of

the same trace that was encountered in Trench T-1.

In conclusion, an active fault was exposed in Trenches T-1 and T-3, approximately

25 to 45 feet west of the western site boundary. No evidence was found for the

existence of an active fault on the site itself. There is evidence along the

exposed fault trace for past lurch cracking and/or sand boil activity.

Drilling and Sampling

The drilling and sampling program was performed on November 2, 1981, and

consisted of a visit to the site by the Soil Engineer, and drilling of test

-9-



borings to obtain samples and other data pertinent to the subsurface soil

conditions. Twelve exploratory borings were drilled to depths of 181:;; to 40 feet

below the existing ground surface. Borings were excavated in accordance with

generally accepted geotechnical exploration procedures (ASTM 01452) utilizing a

6-inch diameter auger. The approximate locations of borings as indicated on

Plate 1, were determined by pacing and sighting from existing buildings, trees

and other features shown on the Boundary and Topographic Survey Map.

Disturbed bulk samples of the soils were obtained from cuttings developed during

excavation of the test borings. The bulk samples were secured for classification

purposes and may represent a mixture of soils within the noted depths.

Relatively "undisturbed" samples were secured within the test borings with a 3-

inch O.D. Modified California Sampler (ASTM 03550 with modified shoe) at selected

intervals within the borings. A 2-inch O.D. Terzaghi Sampler was used at some

locations to obtain penetration resistance data. The samplers were driven by a

140 pound halTlller falling 30 inches (ASTM 01586). The number of blows required to

drive the samplers into the undisturbed soil a measured distance was recorded.

Blow counts obtained for the 3-inch sampler were converted to correlate

approximately with those obtained with the Terzaghi Sampler (Standard

Penetration Test). Pocket Penetrometer tests were also performed on most of the

3-inch samples as they were taken from the borings. The samples were then sealed

in air-tight containers and returned to the laboratory for further

classification and testing.

Logs of Test Borings are included as Figures B-3 through B-17 in Appendix B. The

logs represent the interpretation of field logs and tests, the interpolation of


-· I

F1le No. Cl-1088-Cl November 20, 1981

soil conditions between samples and the results of laboratory observations and

tests. The noted stratification lines represent approximate boundaries between

soil types; the transition may be gradual.

Laboratory Testing

Subsequent to visual classification in the field, samples were taken to the

laboratory, visual classifications were checked in accordance with the Unified

Soil Classification System (ASTM 02488), and a testing program was established.

Samples were reviewed along with field logs to assess which would be further

analyzed. Samples considered as representative of soils which would be exposed

and/or used in grading and those deemed within structure influence were chosen

for further analysis. In-situ moisture content and un1t dry weight for recovered

samples were developed in accordance with ASTM 02937.

The relative strength characteristics of the subsurface soils were assessed from

the results of unconfined compression and direct shear tests conducted on

recovered samples. Direct shear specimens were placed in contact with water at

least 24 hours before testing, allowed to drain briefly, and were then sheared

under normal loads ranging up to 3.0 ksf.

A consolidation test was conducted on a sample obtained with the 3-inch 0.D.

sampler from Boring 9. Loading schedules were used to develop qualitative

information for estimating the magnitude of settlement under various foundation

loads.


•• I


Expansion and shrinkage potential were determined from the results of swell tests

on shear test specimens and the results of Atterberg Limits tests. In order to

evaluate liquefaction potential, grain-size distribution was determined from the

results of sieve and hydrometer analyses performed on representative granular

soils. The results of the field and laboratory tests are summarized in Appendix

B.

-12-


File No. Cl-1088-Cl November 20, ·1981

GEOTECHNICAL EVALUATION AND DISCUSSION

Soil' Conditions

The soil conditions appear to be relatively uniform in the area of proposed

building development. A zone of loose fill (containing some debris) occupies the

depressed area in the southwest portion of the site. The fill appears to be

limited to the area west of the Telephone and Telegraph Easement. Approximately

5 feet of fill was encountered in the west end of Trench T-2 and in Boring 4. Up

to 9 feet of fill was observed in Trench T-1, west of the site. The other boring

that encountered fill was No. 9, where a 2~-foot layer was found in a localized

area behind the existing house. Other areas of localized fill and scattered

debris were observed in the eastern portion of the site.

The upper natural soils at the site consist of a cultivated layer (approximately

1-foot thick or less) of grey-brown silty clay. This surface layer is generally

loose and contains a noticable organic content. Underlying the silty clay layer

the soils are typically stiff to very stiff sandy or clayey silts and silty clays

with occasional silty sand lenses. Dense to very dense sandy gravels were

encountered at depths ranging from 13 to 21 feet in all the borings except No. 4.

Boring 4, which was drilled near the northern edge of the pond area (Tyson's

Lagoon) encountered soft to stiff, silty and sandy clays to the bottom of the

hole at 40 feet.

Except in the area of Boring 4, the in-place density of the soil ranges from

approximately 102 to 130 p.c.f. Natural moisture contents range from

approximately 6 to 22%. The higher densities were found in the dense gravels

-13-



below depths of 13 to 21 feet. These dense gravels are interpreted as the top of

the "Newark Aquifer", a relatively thick, well-defined alluvial deposit. These

gravels were encountered to the maximum depth of drilling (40 feet} in all

borings except No. 4.

The silts and clays above the Newark Aquifer have moderate to high strength

characteristics, and low to moderate swell potential (see Table B-1 in Appendix

B). The soils in the upper 15 (±) feet are moderately compressible under heavy

footing loads, particularly in the layers between about 4 to 10 feet below the

surface. Settlements have been estimated for various foundation types and loads.

The results of these preliminary estimates are discussed in the Conclusions and

Recommendations portion of this report.

Groundwater

Groundwater was encountered in the Newark Aquifer at a depth of approximately 30

feet below the ground surface (see Boring 1). This depth corresponds to a water

surface elevation of approximately 29 (based on surface elevations per

topographic plan by PRC Toups). The water surface elevation is similar to that

reported by Judd Hull and Associates in reports on adjoining properties.

It is understood that the groundwater recharge program of the Alameda County

Flood Control and Conservation District could someday result in the raising of

the groundwater surface to approximately elevation 45, approximately 15 feet

below the existing ground surface.

-14-



A localized, shallow water condition was encountered in Boring 4 and in the

western end of Trench T-2. Boring 4 encountered perched water at a depth of

approximately 13 feet. The water level rose to within about 11 feet of the

surface approximately 4 hours after the hole was drilled. Minor seepage was

observed in the bottom of Trench T-2 near the west property line at a depth of

approximately 10 feet. This water appears to be a localized condition resulting

from migration of water from the adjacent pond (Tyson's Lagoon). Since water was

not encountered in Borings 5, 6 and 7, it appears that the localized, perched

water is limited to. the depressed area west of the Telephone and Telegraph

Easement, and is outside the limits of proposed building construction.

Seismic Hazards

The site could be affected by an earthquake centered on any of the major faults

in the Bay Area. At present, it is not possible to predict when or where movement

will occur along a fault. It must be assumed, however, that movement along one

or more of these faults will result in a moderate to major earthquake during the

lifetime of any construction on this site.

Three major active fault systems are known to exist in the general vicinity of

the site. The San Andreas Fault is approximately 18 miles to the southwest; the

Calaveras Fault is approximately 6 miles northeast; and the Hayward Fault lies

iD111ediately west of the site.

In the event of an earthquake, seismic risk to a structure will depend on the

distance of the structure from the epicenter and source fault, the character and

magnitude of the earthquake, the geologic, groundwater and soil con di ti ans

-15-

I I I I I I I I I I I I I I I I I I

·1


underlying the structure and its immediate vicinity, and the nature of the

construction.

The potential seismic hazards at the site area are ground rupture and related

phenomena, localized ground failure, and structural damage due to ground

shaking. The following is an assessment of the potential for these effects to

occur at this site.

Ground Rupture and Associated Phenomena - Ground rupture may occur abruptly

during an earthquake, or slowly during fault creep. Movement on a fault can be

horizontal, vertical or a combination of both. The width of a ground rupture

zone is usually less than 20 feet, but can be much wider in, for instance,

water-saturated soils. A zone of deformation from 20 to 25 feet wide is

associated with the surface faulting exposed in exploratory trenches in Central

Park, l mile southeast of this site.

Ground rupture tends to occur along lines of previous faulting. The fault trace

identified during this study shows evidence of past horizontal and vertical

displacement. In the event of an earthquake on either the Hayward of Calaveras

Fault systems, centered near the general region of the site, ground rupture could

occur along the fault trace in the site vicinity.

The potential for ground rupture to occur is considered to be very high along the

identified fault trace and in a zone 50 feet on either side of this trace. The

potenti a 1 is considered moderate in the depressed area southwesterly of the

Telephone and Telegraph Easement, and low over the rest of the site.

-16-



Reg1onal subsidence, uplift or lateral movement can also occur suddenly during an

earthquake or slowly during fault creep. The magnitude of these movements can

vary from a few inches to a few feet per event. These phenomena affect large

areas that are bounded abruptly by a fault, along which the rupture takes place.

In the event of such movement related to an earthquake on the Hayward Fault, the

area of the site east of the rupture zone would probably respond as a unit and

follow its previous pattern of movement.

Ground Failure - The potential for landslides or slumps to occur on th1s site

is cons1dered to be low due to the low topographic relief of the ir1111ediate area.

Liquefaction can occur in saturated granular materials as a result of ground

shaking. Relatively shallow groundwater was encountered in Boring 4 and in

Trench T-2, near the southwest corner of the site, but 11ttle or no granular

soils were found in that area. There was evidence of sand boils resulting from

prev1ous liquefaction in two of the trenches. The potential for liquefaction to

occur at this site is therefore considered to be high to moderate in the 50-foot

wide zone on either side of the fault and in the topographic depression in the

southwest corner of the site. Elsewhere on the site, the liquefaction potential

is considered low. The grain-size distribution of the soils above the Newark

Aquifer is generally outside the limits of "easily liquefiable" soils (see

Figures B-21 and B-22 in Appendix B). The absence of shallow groundwater beneath

the areas of proposed development further reduces the potential for

liquefaction. Even if the groundwater were to rise to within 15 feet of the

ground surface, the potential for liquefaction is considered low. The generally

-17-



high density of the soils in the underlying Newark Aquifer results in a low

potential for liquefaction in those materials.

Lateral spreading is the movement of loose soils over low angle slopes into open

areas during an earthquake. The subsurface conditions revealed in the

excavations are such that the potent ia 1 for this phenomenon to occur at the

subject site is considered to be low.

Local subsidence can occur during an earthquake when ground shaking drives water

out of saturated soils, causing ·them to densify. The potential for this

phenomenon to occur at this site is also considered to be low.

Lurch cracking is the formation of various types of fissures or cracks 1n the

uppermost soil layers, and is apparently related to the rapid oscillatory motion

of the ground during an earthquake. If shallow water is present, it is often

forced to the surface during lurch cracking, forming mud volcanoes, sand boils or

water gushers. The potential for lurch cracking to occur is considered to be

moderate to high along the Hayward Fault zone and in the topographic depression

in the southwest corner of the site. The potential is low for lurch cracking to

occur elsewhere on the site.

Ground Shaking - A moderate to major earthquake on the Hayward or Calavaras of

a major event on the San Andreas Fault could cause severe ground shaking at this

site.

Structural damage due to ground shaking is caused by the transmission of

earthquake vibrations from the ground into the structure. The variables which



determine the extent of damage are: the characteristics of the underlying earth

materials, the design of the structure, the quality of materials and workmanship

used in construction, the location and magnitude of the earthquake, and the

duration and intensity of shaking. The most destructive effects of an earthquake

usually occur in areas where the ground is unstable and structures are poorly

designed and/or constructed.

Preliminary estimates of ground response characteristics at these site indicate

that high peak bedrock accelerations can be expected during a moderate to major

earthquake on the Calaveras or Hayward Faults or a major earthquake on the San

Andreas Fault. Surface accelerations are expected to be less than the peak

bedrock values, because of the thickness (300 feet or more) of alluvial soils at

this site. The duration of shaking, ground accelerations, and the frequency

components of the vibrational waves will depend upon the magnitude and location

of the earthquake. The characteristic site period (Ts) is estimated to be

greater than 2 seconds.

The severity of shaking that may affect a site is principally controlled by the

subsurface soil conditions and the design and construction of the structure, and

less by its proximity to a fault trace. Structures at the site should be

designed by an engineer familiar with seismic design. The structures should be

designed to accommodate severe earthquake vibrations. If quality construction

criteria are met, as set forth in the latest editions of the City, County and

Uniform Building Codes, structural damage resulting from ground shaking can be

reduced at this site.

-19-



CONCLUSIONS AND RECOMMENDATIONS

The following conclusions and recommendations are made on the basis of the

results of exploration, tests and evaluations described in this report, and for

the condominium project generally as shown on the drawing entitled "Fremont

Station - Preliminary Review Plan", by the Environmental Center, dated September

2, 1981. If the project development will be substantially different from that

shown on the referenced plans and described in this report, Earth Systems

Consultants should be consulted for possible supplementary reco11111endations. The

following recommendations are intended to minimize the effects of the identified

geotechnical factors at this site.

General

l. The site is considered geotechnical ly suitable for the planned

development, provided the reco11111endations presented in this report are

incorporated into design, and implemented during construction. The proposed

condominium buildings may be supported on spread footings placed in prepared pads

of recompacted native soil or select import fill (see paragraphs 9 through 11).

2. An active trace of the Hayward Fault was found trending northwest

southeast approximately 25 to 45 feet west of the westerly property line (see

Plate l). The potential for future fault displacement, ether sudden rupture

during and earthquake or slow tectonic creep, is high along the identified fault

trace and within a zone approximately 50 feet wide on either side of the trace.

-20-



It is recommended therefore that structures for human habitation be restricted

from a zone at least 50 feet wide on either side of the identified fault trace.

3. The potential for lurch cracking and localized liquefaction is considered

high along the fault trace and within the topographic depression in the southwest

corner of the site. It is recommended therefore that structures not be placed in

this area, which lies generally south and west of the existing contour 53. This

area is identified as a "Building Restriction Zone" on Plate l.

4. Pavements and walkways may be constructed in the restricted areas

described in paragraphs 2 and 3, provided these areas are graded in accordance

with the recommendations of this report.

5. The potential for fault rupture, lurch cracking and liquefaction to occur

east of the above described restricted zones is considered low. The primary

seismic hazard east of these zones will result from ground shaking in the event

of an earthquake. It is recoJ1111ended that structures at this site be designed in

accordance with the applicable lateral force provisions of the latest edition of

the Uniform Building Code. Consideration should be given to the use of

reinforced "tie beams", at or below grade, to structurally connect isolated

spread footings.

6. Static settlement (consolidation) may occur within the upper soil layers

due to concentrated foundation loads. In order to reduce total and differential

foundation settlements to less than about 1 or 2 inches, a program of

subexcavation and recompaction beneath the buildings is recommended (see

paragraphs 9 through 11). Alternative foundation systems, such as drilled piers

-21-



(caissons) or reinforced mats may be applicable at this site. As requested,

however, this report is limited to recommendations for spread footings.

Grading and Site Preparation

7. Site preparation and grading should be performed in accordance with the

following paragraphs and as augmented by the "Suggested Grading Specifications",

presented in Appendix c. These specifications set forth minimum standards needed

to satisfy other requirements of this report. The Soil Engineer, Earth Systems

Consultants, should be present at pre-construction meetings with the

contractor's representatives to review the approved project pl ans and

specifications and discuss the contractors scheduling. The Soil Engineer should

be notified at least 48 hours in advance of pre-construction meetings and grading

operations so that he can coordinate his field personnel and dispatch them to the

site when required.

8. Existing buildings, debris and buried structures such as foundations,

basements, septic tanks, pipes, tree stumps and roots must be removed from the

site. The resulting depressions should be cleaned of loose soil and debris, and

backfilled with compacted f 111. Organically contaminated topsoil should be

stripped and removed, or stockpiled for later use in landscaping areas.

Stripping depths may be 6 inches or more at some locations. Deeper excavation

will be required to remove existing fill materials, such as in the area of Boring

9, around the existing buildings, and in the southwest corner of the site.

Native soils and existing fill materials, if free of organics and other

deleterious materials, may be reused as compacted fill.

-22-



9. The proposed bu i1 ding pad areas shou 1 d be prepared by stripping to a

generally level surface approximately 4 feet below the proposed pad elevation.

The stripped surface should be scarified and recompacted to at least 90% relative

compaction, based on ASTM Test 01557-70. Each pad (and a distance 5 feet beyond

the perimeter) should then be prepared by placing and compacting suitable on-site

materials, or low expansion import fill to the design pad grade.

10. The recommended minimum depth of excavation and recompaction beneath the

buildings should be established by the designers as an elevation at least 24

inches below the bottom of the deepest footings, or 48 inches below pad subgrade,

whichever is lower.

11. Select import material should consist of granular soil having a maximum

Plasticity Index of 12 and a minimum R-Value of 20. The import fill should not

contain rock fragments larger than 2~ inches, but it should contain sufficient

fines to allow trench and footing excavations to stand open in the compacted pad.

Import fill, and native soil fill, placed beneath buildings, garage, driveway and

parking areas should be compacted to at least 90% relative compaction, except for

the upper 18 inches below pavements, which should be compacted to at least 95%

relative compaction.

12. Water wells known to exist on the site, or found during site. grading

operations, should be capped and sealed in accordance with the requirements of

the local governing agency.

13. The exploratory trenches excavated for this study have only been loosely

backfilled. That portion of Trench T-2 which will be within 10 feet

-23-



(horizontally), or beneath a building or parking area should be re-excavated and

the backfi 11 p 1 aced and compacted in accordance with the recommendations for

compacted fill as described in paragraph 11.

Foundations

14. The proposed condominium structures, presently proposed as three-story

over parking, may be supported on continuous strip and isolated spread footings.

To provide more uniform support conditions, and to mitigate the effects of

differential settlement, spread footings should be constructed on compacted soil

pads, prepared in accordance with paragraphs 9 and 10.

15. Spread footings should be placed as shallow as possible {but not less than

12 inches deep) in the compacted fill pads in order to provide at least 24 inches

of compacted soil beneath the footings. For strip and isolated spread footings

having a minimum dimension (width) of 18 inches, and trenched at least 12 inches

into the compacted soil pad, the reco11111ended allowable bearing capacity is 3,000

p.s.f. This value is reco11111ended for combined dead plus live loads and may be

increased by one-third for combined dead, live and seismic (or wind) loads.

16. The estimated range of settlement for footings placed on at least 2 feet

of compacted soil is 1/2 to 3/4 inches for strip footings with loads ranging from

4 to 8 kips per linear foot, and 1/2 to l inch for square footings with loads

ranging from 100 to 400 kips, respectively. Differential settlement between

similarly loaded adjacent footings is estimated to be approximately 25 to 50% of

the total settlement value. Differential settlement between a lightly loaded

-24-

I I I I I I I I I e I I I I I I I I I


strip footing (4 klf) and a heavily loaded spread footing (400 kips), is

estimated to be on the order of 3/4 inch.

Lateral Resistance

17. Resistance to lateral loads may be provided by friction acting on the base

of foundations. The recommended coefficient of sliding friction between

concrete and compacted natve soil is 0.3. Passive resistance acting on the sides

of foundation elements may be computed on the basis of an equivalent fluid weight

of 250 p.c.f. If passive pressure is used in conjunction with sliding friction,

the friction coefficient should be reduced to 0.2.

Retaining Walls

18. For retaining walls incorporated into the proposed condominium

structures, foundations should be designed in accordance with the preceeding

section on foundations. Retaining walls which are separate from the buildings

should be founded on firm natura 1 ground (or compacted fi 11). The footings

should be embedded at least 18 inches below the lowest adjacent grade, and

designed for an allowable soil bearing capacity of 2,000 p.s.f. Assuming a level

backfill condition, the following lateral earth pressures are applicable for

preliminary design purposes;

Wall Condition (level backfill)

Free-standing

Structurally constrained

Lateral Earth Pressure Condition

active

at-rest

-25-

Equivalent Fluid Weight (p.c.f)

40

50

I I I I I I I I I I I I I. I I I I I I


The foregoing values should be increased for sloping backfills or other surcharge

conditions. The recommended 1 atera l pressures assume a "free draining"

condition. If rotation about the top of the wall is constrained, at-rest

pressures should be used and bending moments checked for both triangular and

trapezoidal distribution.

19. Proper drainage behind the retaining walls is necessary to maintain a free

draining condition. Drainage should be provided behind the wall by use of a

perforated 4-inch minimum diameter drain pipe set within a vertical permeable

filter blanket. The permeable filter material should have a minimum width of 12

inches and extend from the top of the retaining wall footing to within 18 inches

of the final exterior soil grade. The drain pipe should be placed near the top of

the retaining wall footing, embedded in the filter material, sloped to drain, and

positively discharged into a catch basin or other positive drainage outfall

fac11 ity.

20. Permeable filter materials for drain systems should consist of Class 2

Permeable per Section 68 of the California Standard Specifications (Caltrans).

As an alternative, concrete aggregates may be used if completely encased in a

filter cloth (E.O.S. :::;_ 70) to mitigate migration of soil fines into the filter

materi a 1.

21. The top 18 inches of backfill behind the retaining walls should be

compacted native soil. The lower half of the 18 inch layer should be.compacted

to at least 90% relative compaction. The final half may be placed in a loose

condition, to allow for landscape planting. Where sidewalks and/or pavement



areas are to exist, either over or immediately behind retaining walls, the filter

material should extend to the top of the wall.

Slab-on-Grade Construction

22. It is recommended that s l abs-on-gr;i.de in the depressed parking areas

consist of a minimum 5-inch thick slab with nominal reinforcing as determined by

the design engineer. The slabs should be underlain by a 6-inch thick rock b;i.se

consisting of Cl;i.ss 2 Aggregate Base (Caltrans Standard Specifications),

compacted to at least 95% relative compaction. Frequent construction joints or

other appropriate methods to contra l concrete cracking are reco11111ended. If

slabs-on-grade are to be used in living areas, or in moisture sensitive areas, a

moisture-proof membrane is recommended beneath the slab. A 1 to 2-1nch layer of

sand is recommended over the membrane to protect it during construction, and to

provide a better curing environment for the concrete.

Utility Trenches

23. Excavation of utility trenches can prob.ably be accomplished with

conventional trenching equipment. It is expected that the side walls of the

trenches excavated in the on-site material would be reasonably stable in a

vertical cut to a depth of 5 feet. Deeper trenches should be properly braced or

sloped in accordance with the requirements of Cal-OSHA. Trenches should be

placed so that the bottom of the excavation does not extend below an imaginary

line projected downward at 2:1 (horizontal to vertical) from the bottom edge of

adjacent footings. Trench backfill should be governed by the provisions of this

report relating to minimum compaction standards. In general, service lines

-27-



should be backfilled with native soils, mechanically compacted to a minimum of

90% relative compaction. The upper 18 inches beneath pavement and slab areas

should be compacted to at least 95%. Backfill operations should be observed and

tested by the Soil Engineer to monitor compliance with these recommendations.

Surface Drainage

24. An important item to be considered for satisfactory performance of this

project is proper surface drainage. It is essential that surface drainage be

controlled to prevent ponding, especially adjacent to the buildings and within

paved areas. Positive surface drainage should be provided by the use of paved

drainage swales, inlets and appropriately designed closed-pipe storm drainage

facilities.

Plan Review

25. It is recommended that the Soil Engineer be provided the opportunity

for a general review of final grading, improvement and foundation plans. This

review is to assess general compliance with the earthwork and foundation

recommendations of this report and for implementation of the recommendations

into the project plans and specifications.

Observation and Testing

26. It is recoTT1Tiended that the Soil Engineer be retained to provide

observation and testing services during site preparation and grading, foundation

excavation and trench backfi 11 work. This is to observe comp 1 i ance with the

design concepts, specifications or recommendations and to allow for possible

-28-



design changes in the event that subsurface conditions differ from those

anticipated prior to start of construction.

I I I I I I

' I I I I I I I I I I I I


LIMITATIONS AND UNIFORMITY OF CONDITIONS

l. The reco11111endations of this report are based upon the assumption that the

soil conditions do not deviate from those disclosed in the borings and

trenches. If variations or undesirable conditions are encountered during

construction, or if the actual construction will differ from that planned at

the present time, Earth Systems Consultants should be notified so that

supplemental reco11111endations can be given.

2. This report is issued with the understanding that it is the responsibility

of the owner or of his representatives to ensure that the information and

recommendations contained herein are called to the attention of the

architect and engineers for the project and are incorporated into the plans,

and that the necessary steps are taken to see that the contractors and

subcontractors carry out such reconmendations in the field.

3. The findings of this report are valid as of the present date. However,

changes in the conditions of a property can occur with the passage of time,

whether they be due to natural processes or to the works of man, on this or

adjacent properties. In addition, changes in applicable or appropriate

standards may occur, whether they result from legislation or the broadening

of knowledge. Accordingly, the findings of this report may be invalidated,

wholly or in part, by changes outside of our control. Therefore, this

report is subject to review and should not be relied upon after a period of

three (3) years.

-30-



4. The body of the report specifically recommends that Earth Systems

Consultants be provided the opportunity for a general review of the project

plans and specifications and be retained to provide observation and testing

services during construction. If Earth Systems Consultants is not given the

opportunity to make the recommended reviews and provide the recommended

services, misinterpretation of the recommendations may result.

5. This report was prepared upon your request for our services, and in

accordance with currently accepted geotechnical engineering practices. No

warranty based on the contents of this report is intended, and none shall be

inferred from the statements or opinions expressed herein.

6. The exploratory trenches excavated for this report have been loosely

backfillled. Earth Systems Consultants assumes no responsibility for

future performance of the backfill in its present condition.

-31-

I I I I I I I I I i I I I I I I I I -• -

APPENDIX A

Literature and Map Review

Aeria.l Photograph Interpretation

Bibliography



Literature and Map Review

The most useful 1 iterature and maps pertinent to this study are listed in the

BIBLIOGRAPHY, page A-10. Most of the published geologic information on this area

is of a preliminary nature, based on reconnaissance and extrapolation of data

rather than on detailed investigation. Detailed geologic investigations have

been done in this part of Fremont, however, by Burkland and Associates {1973,

1976, 1977a,b, 1978), Woodward-Clyde and Associates (1970), Woodward-Clyde

Consultants (1975, 1976), Woodward, Clyde, Sherard and Associates {1962), Judd

Hull and Associates (1976, 1979), Gribaldo, Jacobs, Jones and Associates

(1970a,b) and by Cooper-Clark and Associates (1968).

The regional geology has been mapped by Clark (1915), Hall (1958), the California

Department of Water Resources (1963), Helley et al (1972) and Nilsen (1973).

These maps differ in scale and detail, but they agree that the site vicinity is

underlain at the surface by alluvial fan (non-marine) sediments of Pleistocene to

Holocene age (less than 2 million years old).

Nilsen (1973) and Wright and Nilsen (1974) show no landslide deposits on or near

this site.

The Hayward Fault has been mapped on or immediately west of the site by Clark

(1915), California Department of Water Resources (1963), Brown and Lee (1971),

California Division of Mines and Geology (1974), Radbruch-Hall (1974), C1ty of

Fremont (1975), Jennings (1975), and Herd (1977). The Hayward 1s a

A-1



right-lateral fault with a variable thrust component. In the Fremont area, this

fault consists of a single main active trace that occasionally bifurcates into

two or more parallel traces.

The Hayward Fault has been zoned by the California Division of Mines and Geology

(1974) under the provisions of the Alquist-Priolo Special Studies Zones Act of

1972. The attached Figure A-1, page A-3, shows the location of the site in

relation to the mapped traces of the Hayward Fault and the boundaries of the

Special Studies zone.

The fault has been mapped as a single trace from the hills north of Niles to the

northern end of the Tule Pond (Tyson's Lagoon}, adjacent to the southwest corner

of this site, where it splits and passes southward through Fremont as two

distinct parallel fault traces.

The Hayward Fault often acts as a water-barrier in the Hayward-Fremont area

(Clark 1915, Radbruch-Hall 1974, Burkland and Associates l977a). The water level

east of the fault zone is approximately 40 to 80 feet higher than to the west.

Tyson's Lagoon and Stivers Lagoon (Lake Elizabeth) are both the result of water

accumulation in topographic lows caused by displacement along the Hayward Fault.

Their individual relationships with the fault's two main traces, however, are

different. Diagrammatic cross-sections through both lagoons and the fault zone

are presented on Figure A-2, page A-4.

A-2


File No. Cl-1088-Cl

0

.<."

34 .. J

3000

SCALE IN FEET FAULT LOCATIONS IN CENTRAL FREMONT, ALAMEDA COUNTY, CALIFORNIA.

B Jl.llD HULL, 1976 (Tract 3778)

BOUNDARY OF SPECIAL STUDIES ZONE c JUDD HULL, 1979

CALIFORNIA DIVISION OF MINES AND (34-Unit Apartments) GEOLOGY, 1974

D COOPER-CLARK & ASSOCIATES, 1971 CALIFORNIA DEPAR1MENT OF WATER (Fremont BART Station) RESOURCES, 1963

E WOODWARD-CLYDE-SHERARD & ASSOCIATES, RADBRUCH-HALL, 1974 1962 (Civic Center)

----•••11••11t••••

A WOODWARD-CLYDE CONSULTANTS, 1976 F BURKLAND & ASSOCIATES, 1978 (Shinn Property) (Fremont Community Center)

Fi

A-3


File No. Cl-1088-Cl

Site /

,,,, .. , ~,., Lagoon

Tyson's Lagoon (Tule Pond)

Scarps

Regional Compressive--,,>Forces

Stivers Lagoon (Lake Elizabeth)

LOCATIONS OF LAGOONS IN RELATION , TO TRACES OF THE HAYWARD FAULT

IN FREMONT, CALIFORNIA. (from Radbruch-Hall, 1974, and U.S. Geological Survey Topographic Map, Niles Quadrangle, 1961 ed.)

Graben

> Jt Horst

DIAGRAMMATIC EXPLANATION OF LAGOON FORMATION IN RELATION TO THE HAYWARD FAULT IN FREMONT, CALIFORNIA.

Figure A-2

A-4



Site-specific investigations have been done by various firms in the Fremont area

in efforts to determine the exact location and nature of the Hayward Fault.

These reports are too numerous for a discussion of each one to be of value in this

report. A discussion of only the more notable, or those nearest the site is

presented. The approximate locations of most of the reports discussed are shown

on Figure A-1.

Cooper-Clark and Associates (1968) found the western trace of the Hayward Fault

in a number of trenches along the western side of Tyson's Lagoon, south of the

site. That fault trace was marked, in that area, by an east-facing, semi-linear

scarp. Some of their trenches reportedly showed evidence of near surface

liquefaction in localized sand layers.

Woodward-Clyde Consultants (1976) excavated a total of nine trenches (including

six from a previous study) on the Shinn Property, north of Tyson's Lagoon,

northwest of the site (see Figure A-1). They identified traces of the Hayward

Fault in several of their excavations and classified them as active.

Judd Hull and Associates (1976, 1979) conducted detailed investigations of

properties located immediately north and east of this site (see Figure A-1).

Their studies included the excavation of borings and trenches, a seismic survey

and air photo interpretation. Their borings encountered groundwater at

approximately 30 feet on both properties. They show the Hayward Fault to be from

30 to 60 feet west of the westernmost corner of Tract 3778.



A number of studies have been done in the vicinity of the Fremont Central Park

and Civic Center, near Stivers Lagoon (Lake Elizabeth), approximately l mile

south of this site.

Woodward-Clyde-Sherard and Associates ( 1962) conducted seismic and sub-surf ace

investigations for the then-proposed Fremont Civic Center at the north end of

Central Park. Their study revealed the presence of two roughly parallel traces

of the Hayward Fault.

Woodward-Clyde Consultants (1975) excavated a trench across the postulated

eastern trace of the Hayward Fault in Central Park.

immediately northwest of the northern tip of

Their trench was located

Lake Elizabeth. Their

interpretation of the subsurface conditions in that trench was that there is no

evidence for the presence of a fault in that area.

Burk 1 and and Associates ( l 978) excavated trenches in Centra 1 Park and found

evidence of active faulting in the vicinity of the Community Center. There is

also evidence of fault creep in parking lots, driveways and curbs throughout the

park vicinity.

Burkland and Associates (1973, 1976, 1977c) excavated a number of trenches on

several connecting sites immediately west of the Southern Pacific Railroad

tracks, south of Paseo Padre Parkway. Active traces of the Hayward Fault were

found on those properties.

Burkland and Associates (1977a) and Gribaldo, Jones and Associates (1970a) found

a number of traces of the Hayward Fault on the Paseo Villages property,

A-6



approximately 4 miles southeast of the site. The westernmost of these traces was

seen to be a water barrier, and to be actively creeping. This western trace was

also mapped by Gribaldo, Jacobs, Jones and Associates (1965) in the residential

area north of the Paseo Villages property, where it has offset and cracked curbs

and pavement on Gardenia Way and Grimmer Boulevard.

Creep along the Hayward Fault in this area was first noted and mapped by Bonilla

(1966), based on deformation of railroad tracks southeast of the site; and by

Cluff and Steinbrugge (lg66), based on offset and cracks within a building

immediately west of the railroad tracks, southeast of the site.

In 1836, an earthquake centered in the Hayward Fault zone (estimated Richter

magnitude 7.0), ruptured the ground from San Pablo to San Leandro. In 1868,

another earthquake (estimated Richter magnitude 7 .0), also centered in the

Hayward Fault zone, approximately 2 miles southeast of the site, caused the

ground to rupture from San Leandro to Warm Springs. During the latter event,

cracks reportedly occurred in the ground at the north end of Tule Pond (Tyson's

Lagoon)_ on or adjacent to the southwest corner of this site (Radbruch-Hall,

1974),

Three major earthquakes are known to have occurred in the San Andreas Fault zone

in the Bay Area during the last 150 years. In 1838, an event of estimated Richter

magnitude 7,0 was centered approximately 22 miles to the west; in 1865, an

earthquake of estimated Richter magnitude 6.5 was centered approximately 20

miles to the southwest; and the event of April 18, 1906 (Richter magnitude 8.3),

A-7



was centered off the Golden Gate, approximately 40 miles northwest of the site

(Boore, 1977; Rogers and Williams, 1974).

All of these events, on both the Hayward and San Andreas Faults, probably caused

moderate to severe ground shaking at this site.

Borcherdt, et al. (1975), by computer analysis, attempted to predict intensities

in the Bay Area in response to a 1906-type earthquake. Their intensity zones are

largely based on a classification system devised by Wood (1908, p. 224-225).

Wood's system is based upon apparent intensities resulting from the earthquake of

April 1906. This site lies within Wood's Category A, which is defined as

follows:

"Grade A. Very violent - Comprises the rending and shearing of rock masses, earth, turf, and all structures along the line of faulting; the fall of rock from mountainsl1des; numerous deep, and extended fissuring in natural earth; some structures totally destroyed."

Borcherdt, et al. (1975, p. 11) shows Wood's "Grade A" to be equivalent to a 10 on

the Rossi-Forel scale or a X to XII on the modified Mercalli scale.

The site is located within Seismic Hazards Zone l, as defined by the City of

Fremont (1975). This zone is drawn along the Hayward Fault in this area and is

defined as being characterized by a narrow zone of surficial faulting.

The site is also within zone BsHl, which denotes areas in which bedrock is at a

depth of 300 feet or more. This zone is defined as having a potential for

A-8



moderate ground shaking and low to high liquefaction potential, depending on the

topography, groundwater conditions, etc. (City of Fremont, 1975).

The U.S. Geological Survey (1969) shows flood limits within central Fremont to be

restricted to an area around Stiver's Lagoon. The northern boundary of this zone

is approximately 3000 feet southeast of this site. The evaluation of potential

flood hazards at this site was outside the scope of this report.

Aerial Photograph Interpretation

The following aerial photographs, from the files of Earth Systems Consultants,

were used for this evaluation:

~

November 22, 1950

June 1, 1954

August 11, 1957

July 9, 1963

May 12, 1972

Scale

1:12,000

1:12,000

1:20,000

1:12,000

1 :36,000

~

Black and White

Black and White

Black and White

Black and White

Black and White Infrared

These photographs were scrutinized for the presence of terrain features

characteristic of active fault zones, particularly lineations. A lineation is

seen on a stereo aerial photo pair as a feature with tonal differences on either

side. These differences may indicate changes in soil types, vegetation,

groundwater levels or sedimentary bedding characteristics.

sometimes fault related.

A-9

L ineations are



Scarps are visible on all photos along the east and west sides of Tule Pond

(Tyson's Lagoon). They are especially clear in the 1950, low-sun-angle photos.

There appears to have been some compression between the fault traces at the

southern end of the Pond, but the northern end, adjacent to this site, appears to

be a graben (depression).

Two very strong, roughly parallel lineations trend northwest~southeast through

Central Fremont. The westernmost of these appears to bifurcate from the eastern

trace in the vicinity of the two sets of railroad tracks southeast of the site

(see Figure A-2).

The western trace then trends slightly westward, becoming approximately parallel

to the eastern trace by the time it crosses the East Bay Aqueduct. North of the

Aqueduct, its trend is northwestward, roughly parallel to Paseo Padre Parkway, as

far as its intersection with Mission View Drive. The fault then cuts across

Central Park, bending eastward to join the eastern trace again at the north end

of Tyson's Lagoon, near the southwest corner of this site.

The eastern trace is the more linear of the two, trending northwestward through

Central Park. This trace appears to form the western limit of Lake Elizabeth

(Stivers Lagoon and marsh) and the eastern boundary of Tyson's Lagoon (see Figure

A-2).

These two lineations correspond with the mapped locations of the two main traces

of the active Hayward Fault in the Fremont area (Radbruch-Hall 1974, and others).

A-10



The fault zone, as seen on the photos, acts as a water barrier. The area west of

the fault zone appears to be unaffected by shallow groundwater and the cultivated

fields are uniform in color and tone. The area between the two traces is darker

in color and is spotted with native vegetation and possibly with springs.

Tyson's Lagoon appears as a dark, very wet area with an undefined southern

boundary, between the two lineations. The area immediately east of the

lineations is very dark and heavily vegetated, particularly in a zone between the

railroad tracks to the south and the present Stevenson Boulevard on the north.

This dark, wet area has been mapped as Stiver's Lagoon or Pond and originally had

no distinct boundaries, except along the fault. The lagoon, as viewed at

different times of the year and from year to year, changed in character, depth

and extent depending upon the amount of water available. Stiver's Lagoon has now

been confined into Lake Elizabeth and its ori gi na 1 boundaries changed and

defined. The marsh at its southern end has a 1 so been conf 1 ned but the thick

growth of native vegetation remains.

A-11


File No. Cl-1088-Cl November.20, 1981

BIBLIOGRAPHY

1. Bonilla, M.G., 1966, DEFORMATION OF RAILROAD TRACKS IN FREMONT, CALIFORNIA, Geological Survey Circular 525, pp. 6-8.

2. Boore, O.M., 1977, STRONG-MOTION RECORDINGS OF THE CALIFORNIA EARTHQUAKE OF APRIL 18, 1906, Bulletin Seismological Society of America, Volume 67, No. 3.

3. Borcherdt, R.O., J.F. Gibbs and K.R. Lajoie, 1975, EARTHQUAKE INTENSITIES, SOUTHERN SAN FRANCISCO BAY REGION, CALIFORNIA, U.S. Geological Survey Miscellaneous Field investigation, Map MF-709.

4. Brown, R.O., Jr., and W.H.K. Lee, 1971, ACTIVE FAULTS AND PRELIMINARY EARTHQUAKE EPICENTERS (1969-1970) IN THE SOUTHERN PART OF THE SAN FRANCISCO BAY REGION, U.S. Geological Survey Basic Data Contribution 30.

5. Burkland and Associates, 1973, PRELIMINARY GEOLOGIC AND SEISMIC HAZARDS INVESTIGAITON, MOTOZAKI ANO OLIVERIA PROPERTIES, FREMONT, CALIFORNIA.

6. , 1976, SUPPLEMENTARY GEOLOGIC INVESTIGATION, TRACT 3716, FREMONT, CALIFORNIA.

7. , l977a, GEOLOGIC AND SEISMIC HAZARDS INVESTIGATION, PASEO VILLAGES, FREMONT, CALIFORNIA.

8. , 1977b, GEOLOGIC AND SEISMIC HAZARDS INVESTIGATION, TRACT 3857, FREMONT, CALIFORNIA.

9. , 1978, GEOLOGIC AND SEISMIC HAZARDS INVESTIGATION, COMMUNITY CENTER BUILDING ADDITION, FREMONT, CALIFORNIA.

10. California Department of Water Resources, 1963, ALAMEDA COUNTY INVESTIGATION, California Department of Water Resources Bulletin 13.

11. California Division of Mines and Geology, 1974, SPECIAL STUDIES ZONES, NILES QUADRANGLE.

12. Clark, W.O., 1915, GROUNDWATER RESOURCES OF THE NILES CONE AND ADJACENT AREAS, CALIFORNIA, U.S. Geological Survey Water Supply Paper 345.

13. Cluff, L.S. and K.V. Steinbrugge, 1966, HAYWARD FAULT SLIPPAGE IN THE IRVINGTON-NILES DISTRICTS. OF FREMONT, CALIFORNIA, Bulletin of the Seismological Society of America, Volume 56, No. 2.

14. Cooper-Clark and Associates, 1968, SOIL INVESTIGATION A709, SOUTHERN ALAMEDA-FREMONT, prepared for Bay Area Rapid Transit District.

A-12



15. Fremont, City of, 1975, SEISMIC SAFETY AND SAFETY ELEMENTS OF THE GENERAL PLAN.

16. Gribaldo, Jones and Associates, 1970a, INDIAN HILLS PUD, UNIT ND. 2, FREMONT, CALIFORNIA.

17. , 1970b, SOIL INVESTIGATION FOR BRANSON APARTMENTS, FREMONT, CALIFORNIA.

18. Hall, C.A .• Jr •• 1958, GEOLOGY AND PALEONTOLOGY OF THE PLEASANTON AREA, ALAMEDA AND CONTRA COSTA COUNTIES, CALIFORNIA, University of California, Publ. in Geological Science, Volume 34, No. 1.

19. Helley, E.J., K.R. Lajoie and D.B. Burke, 1972, GEOLOGY MAP OF LATE CENOZOIC DEPOSITS, ALAMEDA COUNTY, CALIFORNIA, U.S. Geological Survey Basic Data Contribution 48.

20. Herd, O.G., 1977, MAP OF QUATERNARY FAULTING ALONG THE HAYWARD AND CALAVERAS FAULT ZONES, NILES AND MILPITAS 7 1/2' QUADRANGLES, CALIFORNIA, U.S. Geological Survey Open F.ile Map No. 77-645.

21. Hull, Judd and Associates, 1976, SOIL AND GEOLOGIC INVESTIGATION FOR TRACT 3778, FREMONT, CALIFORNIA.

22. , 1979, SOIL AND GEOLOGY INVESTIGATION, PROPOSED 84-UNIT APARTMENT COMPLEX, TYSON LANE, FREMONT, CALIFORNIA.

23. Jennings, C.W., 1975, FAULT MAP OF CALIFORNIA, California Division of Mines and Geology, Geologic Data Map Series, Map 1.

24. Nilsen, T.H., 1973, PRELIMINARY PHOTOINTERPRETATION MAP OF LANDSLIDES AND OTHER SURFICIAL DEPOSITS ON THE LIVERMORE AND PART OF THE HAYWARD 15-MINUTE QUADRANGLES, ALAMEDA AND CONTRA COSTA COUNTIES, CALIFORNIA, U.S. Geological Survey Basic Data Contribution 59.

25. Radbruch-Hall, D.H., 1974, MAP SHOWING RECENTLY ACTIVE BREAKS ALONG THE HAYWARD FAULT ZONE AND THE SOUTHERN PART OF THE CALAVERAS FAULT ZONE, CALIFORNIA, U.S. Geological Survey Miscellaneous Investigation Series, Map I-813.

26. Rogers T.H. and J.W. Williams, lg74, POTENTIAL SEISMIC HAZARDS IN SANTA CLARA COUNTY, CALIFORNIA, California Division of Mines and Geology, Special Report 107.

27. U.S. Geological Survey, 1969, MAP OF FLOOD-PRONE AREAS, NILES 7.5' QUADRANGLE.

28. Wood, H.O., 1908, DISTRUBUTION OF APPARENT INTENSITIES IN SAN FRANCISCO, Carnegie Institute, Washington, Publ., Volume l, pp. 224-225.

A-13



29. Woodward-Clyde and Associates, 1970, FREMONT MEADOWS ACTIVE FAULT INVESTIGATION AND EVALUATION, FREMONT, CALIFORNIA.

30. Woodward-Clyde Consultants, 1975, FAULT EVALUATION, FREMONT CENTRAL PARK SNACK BAR, FREMONT, CALIFORNIA.

31. , 1976, ALQUIST-PRIOLO SPECIAL STUDIES ZONE REPORT, SHINN PROPERTY, TRACT 3613, FREMONT, CALIFORNIA.

32. Woodward, Clyde, Sherard and Associates, 1962, SEISMIC INVESTIGATION OF HAYWARD FAULT - PROPOSED CIVIC CENTER PROPERTY, FRAMONT, CALIFORNIA.

33. Wright, R.H. and T.H. Nilsen, 1974, ISOPLETH MAP OF LANDSLIDE DEPOSITS, SOUTHERN SAN FRANCISCO BAY REGION, CALIFORNIA, U.S. Geological Survey Basic Data Contrubution 63.

A-14

I I I I I I 'I I I I I I I I I I I •

I I

APPENDIX B

Logs of Trenches

Logs of Test Bor1nqs

SL11111ary of Laboratory Test Results

Plasticity Chart

Consol1dat1on Curve

Grain-Size D1str1bution Curves

I FILE NO. Cl-1088-Cl

I I ,,

WEST O p

o-

5-

10-

WEST

TRENCH T-1 (North Wall)

10

i'•) 111 I_, A ·-1· 1• - · ·"'' I""''· -''l''''I ·1 (I ', «t(- 1."1 11 - 111·.

11-·1 I I L lt 1,J·. \~· 111

'

•i I i :I :Jcl:ii:1'11•11 {: f l1f/ · i ' \ ' J ~) ' I ·JJ I~ i' I ' • j ' ' ' • ,f

I ~J: ·~I' l 'i•t•ll r• r '1 I I . J.~1r,!l1~11:11·f:'1'/;J /·.1 r'

11I1:·, .··11/, ·" '" ' ' 11

0 '

10-

; ' r i r' I I ff r ,r I .. 1, .' ; 2' , I

Sand Boil

10 '

Fi 11

Trace

l

9

20 I

• Barbed Wire •

30 EAST

----/ ..... I ' ' ' '---"'')

Existing Stonn Drair.


20 30 l I

I I I I I I I I I I I I I I .I

Cobbles Fault Trace

40 I

5

6

7

L E G E N D

l

2

3

4 5

6

7

B

9

10 11

12

A

B

c

Cultivated soil meduim brown silty CLAY, dry Mottled •grey and tan-brown silty CLAY Mottled grey tan clayey fine SAND Grey clayey SI LT Medium brown silty CLAY Mottled grey and brown silty CLAY Dark grey silty CLAY Tan clayey SAND Grey brown silty CLAY Olive clayey SILT Grey silty CLAY Medium grey si,lty CLAY

Attitude Nl0°W Vertical' (Trench T-1} N35°W 73°E (Tr~nch T-1) Dip 23°E (Trench T-3)

I

40 50 EAST

' l

l

LOG OF TREWCHES T-1 AND.T-3

Figure B-1

FILE NO. Cl-1088-Cl 1--~~~~~~~~~~~~~~~~--.~~~~~~~---------~_-__ -_-__ -__ -__ -_--~--------=---1 I I I I I I ·I I I I I I I I .j, .,

WEST


0 10 20 30 40 50 60

0- 1\-~~~~--~~~-'~~~~~~~~~'~--~~~~~~~~~~~~~~~~~~~~~~~~~~l~~~,.-~~~~~'~~~~-:;~,;-continued

10

. -:. . :. . . . .. Charcoal

130

LOG OF TRENCH T-2 5-

., Figure B-2 ~--------------------------~----~~----~----~~~~~--~~~----~------~--~--~--~~----------------~~--~--~----.....-----.....

NOTE: See Figure B-1 for Legend

_,

I I I I I I I I I I I I I I I I I •• I

KEY TO LOGS OF BORINGS

ISJ 3-inch 0.0. Sampler

ITJ Terzaghi Sampler

~ Bulk Sample

0 Pocket Penetrometer Test Result

CD Torvane Test Result

'Sj. Groundwater after Stabilization

SZ Groundwater at time of Ori 11 ing

Note; Penetration Resistance as shown for 3-inch 0.0. Sampler is correlated value approximating Standard Penetration Test Value.


File No. Cl-1088-Cl

""'" ~Pt.,.E; 1.0G II --,. NO. l,OCATION "99it111M11

Fl!J!T OF .. -.. _.tt

" O· • •

• . . .

2J 1- l 17 • •

• 5· . . . . . •

• • 1-2 Z1 10 • l 0 • • . • •

• • . . 1-3 0 18 ·15· • •

• . . . • . 1-4-1 21 ~· • 20. 1-4-1

• . . •

• . • . . 25' . . . . • 28·

IN- PLAC!

DDCltllt1 lQllJ ... Jlj01STUM'.

DENSITY C:ON11£NT .... %'*¥ ••.

Boring 1 - Approx. Elevation 59

Grey-brown si 1 ty CLAY with organics, \dry, di seed (CL)

4. 5+

Yellow-brown fine sandy SILT, 0 110. 9 15. l slightly damp, very stiff (CL)

2. l

Yellow-brown clayey SILT with fine sand, moist, stiff (CL)

0 102.5 22.5

4.0

Ye 11 ow-brown and light grey 0 118. 5 13.2 mottled fine sandy SILT, moist, very stiff

Yellow-brown clayey fine sandy l . 6 SILT to sandy clayey SILT,

moist, stiff 0 112. 7 16.6 129. 7 9.7

Fine to coarse GRAVEL (subround, to 3") in orange-brown silty sand matrix, damo, dense (GW)

Fine to medium GRAVEL in clayey sand matrix, damp, dense (GC)

Figure B-3 Log of Boring l (cont. on Figure B-4)

8-3

I I I I I I I I I I I I I I I I I ., I

File No. Cl-1088-Cl

"""" SAM PL!:: 1.,.0G !ti IP-itratiGn

'" NO. l.JX'A.TION ~,-

"''"' o; ........ -ft

• . • 30. 1-5 40

• • . . • •

• . • 35 . . . • •

• • ... _ • •

1-6 57 • 40. • . • • . . • . . . • • . . . . . . . . . . • . • . . . . . . . . .

I~- 1"1..ACE

~tlll'TION ... 'ilOl'STURt OiN51TY CONTI NT .... %..., .. ,_

Boring l (continued)

Fine to medium GRAVEL in clayey _sz_ - -\ sand matrix

Coarse GRAVEL, dense, saturated (GP)

Gravelly SAND - sandy GRAVEL, saturated, dense (SW-GW)

Well-graded GRAVEL (subround, to 6"), saturated, very dense - -

Boring terminated at 40 feet . Date of dril 1 i ng - October 2, 1981.

Figure B-4 Log of Boring l

B-4 ·


File No. Cl-1088-Cl

[Ff; $4f,1i;i~e; l.OQ ~ ........ ; .. '" NO. LCCAT10'4 -·-o• .. .,. ...... , •-'tt

• O· • •

• • 2J 2-1 20 • •

• . • 5·

ZJ . .

2-2 18 . . • •

• . • 10 •

• . • .

2J 2-3 14 • •

• . ·ls· . . • • . .

h-. . I 15 2-4 • 20. 26

. .

. . • . . . . . . . . . .

lfllT Pl.t,C(

OESe•IPT ~ON , ... MOISTUM Di"4SITY CONT!NT .... 94,.., lilt .


Grey-brown silty CLAY with organics, \ dry, di seed 4. 5+

Yellow-brown fine sandy SILT, 0 111. 7 12. l slightly damp, very stiff (ML)

4.5

Reddish-brown (grey mottled), 0 114.8 14.5 clayey fine sandy SILT, damp, very stiff (Cl)

3.5

Medill"TI brown to yellow-brown 0 112. 7 17.2 clayey sandy SILT, damp, to very stiff (ML)

stiff

l. 7

Tan silty CLAY, moist, stiff (CL) 0 Sandy GRAVEL, damp, dense (GW) 123.8 12.7

Boring terminated at 20 feet . Date of drilling - October 2, 1981. No groundwater encountered.

Figure B-5 Log of Boring 2

B-5


File No. Cl-1088-Cl

"""" SAMPLI;'. 1,.0G & ,. NQ. l.OCA110ti .... -,.., Of ....... ,,_, ..

• 0· • . • .

j • . 3-1 15

. .

. 5 •

• •

21 • • 3-2 13

• . • . ·lo· • . . .

0 3-3-1 l? . . 3-3-2

• •

·is· • • . . • .

3-4 /1 ~~

• . • 20.

• • . . . . . . • . . . . •

• •

IN• ~LAC!

DDCRt~TIOlf , ... l«>llTUM: Dl!.MllT't C:ONTl!"N1' .... '% dfy "''·

Boring 3 - Approx. Elevation 61 \Grey-brown silty CLAY with organics,

debris, dry, loose (CL) 4.5+

Yellow-brown clayey fine sandy 0 110.8 11. 8 SILT, slightly damp, stiff to very stiff (ML)

2.5 Reddish-brown-yellow-brown-grey 0 108.5 18.5 mottled fine sandy clayey SILT, moist, stiff (ML)

Tan silty CLAY with fine sand, moist, stiff (CL) -with tree rootlets 108.8 18.2

112. 5 16. 1

Orange-brown-grey mottled silty ' fine to medium SAND, moist,

mediLUll dense (SM)

/Yellow-brown sandy GRAVEL, damp verv dense (GW) 132.0 6.3

Boring terminated at 19 feet. Date of drilling - October 2, 1981. No groundwater encountered .


B-6

I I I I I I I I I

' I I I I I I I ., I

File No. Cl-1088-Cl

""'" SAM PL! LOG 8 ,. ""- r,,JX&Yll)W ... .._ "" .. .,. .. ..,_. -'"

• O· . . . . • • -. . 4-1 ll 14 • 5· . . . • . . . . 4-2 2J 9

• l 0. . . . . . . . . 4-3-1 21 6

4-3-< 12 ·15· . . . . • . -• . 4-4-1 I 9 4-4-' • 20. . . . .

4-5 • . . . • 25· . . . . • 28'

llril• PL•CE:

~lftTI°" .. , MDI STU~

D!HSIT't C°"Tl"1" D-4.t, ,...., ...

Borlng 4 - Approx. Elevatfon 52

FILL: Yellow-brown clayey SILT, damp, stiff (ML)

sandy

4.0

FILL: Dark brown sandy SILT 0 114.3 13. 6 with minor gravel, damp, stiff (ML) FILL?: Yellow-brown clayey sandy SILT, moist, stiff (ML)

1. 6

Olive-grey (red-brown streaked) 0 92.2 29.6 silty CLAY, moist to wet, stiff

(CL) '5Z. ...,..

~ Grey sandy CLAY, saturated, 0 82.0 38. l soft (CL) l .4 84.8 36.6

Olive-rrey silty CLAY, damp, 0

stiff CL) l . 5

0. 5 0 Olive (red-brown mottled) clayey CD

90.8 28.9 fine sandy SILT, saturated, firm 91. 4 27.4

O": 2

Greenish-grey sandy CLAY, saturated, soft (CL)

Medi um grey sandy CLAY, moist, stiff (CL)

Figure B-7 Log of Boring 4 (cont. on Figure B-8)

B-7


File No. Cl-1088-Cl

llEPT• $4MP1.E l.QQ /Ji ~irtivn

•• NO. t.DCllTlor.I RRitfWMll o• ll'!!T ....... _, . • •

4-6 61 • 30• • • . •

• •

• . • 35. . . • •

. . • •

4-7 14 • 40. • •

• . . . • •

• . . . . •

• . . . . . . . . . . . . . . . . • . .

IN- Pt.AC.£

DBO!f•110N

'"' Mi;'.111!1T1,1Ji£

O!NSITY CONTl"HT P.111:.f. % dry wt.

Boring 4 (continued)

Medi um grey sandy CLAY, moist, stiff (CL)

Dark grey sandy stiff (CL)

CLAY, moist,

- -

Boring tenninated at 40 feet. Date of drilling - October 2, 1981.


B-8


File No. Cl-1088-Cl

"'""" ~PLE L.Ca ~ ,. NQ, lDCATIOJil RMittGMil

"'"' O> ....... """"'"

I. O·

- . . .

5-1 t2l 14 • • . . . 5 . • .

2J 5-2 24 - . • . • . -10· • . . .

L1 5-3 27 • . . . • 15 • • . . . . .

~-. . 5-4 41

• 20. . . . . . . . . . . • . . . . .

IN-PL.AC!

crsat41'TIOfl .. ., lm)l:!iTUM;

Dl:NSIT'1 CONTl:Nf IL~f. %. dry wi.


Grey-brown silty CLAY with organics, disced, drv 4. 5+ Yellow-brown (light grey red-brown 0 109. 2 14. 1 mottled) clayey fine sandy SILT, sliohtlv damo, stiff (ML) Light yellow-brown sandy SILT, slightly damp, stiff (ML)

4. 5+ Grey-reddish-brown mottled fine sandy CLAY, damp, very stiff (CL)

0 112.4 17.6

Yellow-brown fine sandy CLAY to sandy clayey .SILT, very stiff (CL-ML) 4.5+ Orange-brown-grey mottled sandy 0 128.4 10.6 CLAY with minor gravel, damp, very stiff (CL)

GRAVELS (subround, to 3'') in orange clayey sand matrix, becoming cleaner with depth, slightly damp, dense

(GC-GW) - -

Boring tenninated at 20 feet . Date of drilling - October 2, 1981. No groundwater encountered .


8-9


File No. Cl~l088-Cl

-H SAMP.L~ 1,,0G a ,. NO. i,.Oc:a'rll)N RMiafMllllll .... "' ....... .._, . . 0· • • . . . .

2J 6-1 18 . • . 5·

• • . . • • -• • 6-2 I 14 • l 0. -

• . • . • •

5-3-1 0 ~~ . . 6-3-i

• 15.

• . . . • . . . 6-4 m 41 ~20·

. . • . . . . . . . • . . . . .

IN- Pt.ACE

CIBOll~TIOM ... J«ll!STUN:

Dl:NSITY COliTIENr p.-.f. ~*" wt

.Boring 6 - Approx. Elevation 56

Light grey-brown silty CLAY, 1 disced, dry, loose (CL)

4.5

0 Light brown clayey fine sandy 114. 3 14.0 SILT, slightly damp, very stiff -damp (ML)

2.6 Dark (reddish-brown mottled) fine sandy CLAY, moist, stiff 0 113. l 17. 6 to very stiff (CL) Light yellow-brown fine sandy clayey SLLT to sandy CLAY, moist, stiff (ML-CL)

Orange-brown sandy CLAY, moist, 2.4 very stiff (CL) 0 120. l 12.7

GRAVEL, subround, fine to coarse, 129.6 10. 1

in a silty sandy matrix, damp, dense (GW)

Gravelly SAND to sandy GRAVEL, dense - -

Boring tenninated at 19; feet . Date of drilling - October 2, 1981. No groundwater encountered .


B-10


File No. Cl-1088-Cl

""'" SAM PL!. LOG &. ~ .. '" ""- 1.DCATIOfil Ralitfllllol ,,..., o• ........ ....., .

• O·

- . . . - . • . • 5 • • •

• •

• . • . ·10· • •

• . • . • . • 1 5 • • . . . . . - . • 20.

• • . . . . . . . . . . • • . .

IH•Pt...f,Ci:

OPCltl~TIOM ,, .. MOISTUll!t

ot~:!ITl' CONTl!H'I' p.e;.t. ~dry~·-


Light brown silty CLAY (di seed to 10"), dry

Yellow-brown sandy clayey SILT to silty CLAY, s 1 i ghtly damp, stiff {ML-CL)

Greenish-tan sandy clayey SILT, , damp, stiff (ML)

Grey (red-brown mottled) sandy CLAY, moist, stiff to very stiff (CL)

Ye 11 ow-brown fine sandy CLAY, moist, stiff

-with gravel (to 3'' ) (CL-GC)

Fine to coarse GRAVEL, subround, damp, dense (GW)

Boring terminated at 18i feet. Date of drilling - October 2, 1981. No groundwater encountered .


B-11


File No. Cl-1088-Cl

"""" SAM PL,! LOG A. ,._.,._ ,. ""- !.llCATIOH .... .-

"'"' o• ....... -·

O• IX • • A

. . -

. . x • • B

. 5 •

• • x c • •

-. . . . • l 0 • • • . . . . • . • 15 • • •

• . . . . . • 20. . . . . . . . . • . . . • . • .

IN• PL~CI!:

cac.111,.TIOft

""' M01!TUM:

Dr:NllTV ~ONT!NT

p.c,t. 'dry -·· Borinq 8 - Aoorox. Elevation 59

Light grey-brown sandy CLAY, \disced, dry (CL)

Yellow-brown clayey fine sandy SILT, damp, stiff (ML)

Greyish-brown stiff (CL)

sandy CLAY, moist,

Yellow-brown fine sandy CLAY, moist, stiff (CL)

Sandy GRAVEL, damp, dense ( GW)

Boring terminated at 18! feet. Date of drilling - October 2, 1981 . No groundwater encountered .


B-12

I I I I I I I I I I I I I I I

' I I I

File No. Cl-1088-Cl

-H $AMPt,,E l.00 e. P'l!NfnlliiQlll

'" NQ, IDCl.TtOrt Attitfll:IMlt

""'' o• .....,tt .. ...u:

• O• . • . .

Z} 9-1 'J . . • • . s· • • Zl 9-2 11 • •

• . . . • 10. • • . .

2J 9-3 -

I' . . • . • 1 s · • • . . . . . . • 20.

• . . . . . . . • . . . • •

• •

IN• PLAC!

r.na""'°" .. , MOISTUM:

C!N!UTV COlll'TE!(f ..... %. d;y wt .

Borino 9 - Annrox. Elevation 60 FILL; Light grey silty CLAY, disced FILL; Dark grey-brown silty CLAY with organics, damp, stiff (CL) 4.0

0 110. 7 17.5

Yellow-brown (grey mottled) l. 75 c 1 ayey sandy SILT, moist, 0 103.0 21.8 stiff (ML)

Grey-brown and tan mottled sandy CLAY, moist, stiff (CL)

Grey-brown cl~y~~ sandy SILT, 1 moist, stiff ML 113. 2 17.9

Tan silty SAND, moist, medium I dense (SM)

Light olive-brown silty CLAY, moist, stiff (CL)

Sandy GRAVEL, damp, dense (GW)

Boring terminated at 18! feet. Date of drilling - October 2, 1981. No groundwater encountered .


B-13


File No. Cl-1088-Cl

""'" SAMPL!: LOG a ~;;~

'" ""· t..DCATIO~ ~iatlMcit

Fm "' ........ ......, . • o . . . . . . . • . • 5· • •

• •

• •

• . ~ 10. • . . . • . • •

• 15·

• . . . • • . . • 20. . • . . . . . • 25. . . • •

• •

IN• PLAC!

COCIH~TIOM

'"' lill01STUM:

t\1£NSITY cOrfT!MT jt.tlf . %~ •*·

.

Boring 10 - Approx. Eleva ti on 60 Light grey-brown silty CLAY with

, organics, disced

Yellow-brown sandy CLAY to sandy clayey SILT, damp, very stiff (CL-ML)

Yellow-brown clayey sandy SILT, moist, stiff (ML)

Dark yellow-brown fine sandy CLAY, moist, stiff (CL)

Light yellow-brown fine sandy clayey SILT, moist, stiff (ML)


Boring terminated at 21 feet. Date of drilling - October 2, 1981 . No groundwater encountered .


8-14


File No. Cl-1088-Cl

IE'T• $4MP1.E 1..00 "' FWNifnlfiOft

'" •o. 1.1:.lf;,t.TIOlll ....--"' m:r ........ --~

• O• . . . . • • . . • s· . . . . • •

• •

• 1 o· . . • . • •

• . • 15· • . • . . . . . • 20· • . . . . . • . . . . . • •

• .

I~~ P1.•c£

i;iaeA1Pf 1(111 .. , MOl.STUM Dl!HSITV """""' ..... ...,.,. ...

Baring 11 - Approx. Elevation 60 Light grey-brown silty CLAY,

1 disced, drv

Yellow-brown clayey sandy SILT, damp, very stiff (Ml)

-stiff, moist

Medi um brown sandy clayey SILT to fine sandy CLAY, damp, stiff

(ML-CL)

Light ye 11 ow-brown c 1 ayey fine sandy SILT, moist, stiff (ML)

-with occasional fine gravel

Sandy GRAVEL, damp, dense

Boring terminated at 18t feet. Date of drilling - October 2, 1981. No groundwater encountered .

• Figure B-15 Log of Boring 11

B-15


File No. Cl-1088-Cl

"""H ~Pt..E; i,..OG a ~*"11ii~

'" NO- UXAl'ION .... -,...,. "" ....... .. ...,. . • (}

• . . .

0 12-1 15 . •

• •

• 5· • •

• . • •

12-1- Zr . -

• • 12-1- '~

• l 0 •

• • . . • . • . 'l 5 • . . • • . . . . • 20 . . . • . • • . •

·25· . . • . . .

IN- Pt.ACE:

otSCltlflTION

''" M('H:!ITU~

i;>(llt!!!l"t't COtiltlEl'(f lloiLI. % ..,. ....

Borinq 12 - Aoorox. Elevation 58

Grey-brown silty CLAY, disced, dry 3.0

Grey-brown silty CLAY, damp, 0 104.2 21.0 stiff to very stiff (CL)

Yellow-brown fine sandy SILT 0.7

0 moist, firm to stiff (ML) 102.9 22.9 2.0 108.8 19. 2

Grey (red-brown mottled) 0 silty CLAY. damp, very stiff (CL)

Yellow-brown sandy CLAY, moist, sti f_f to very stiff

(CL)


Boring terminated at 23! feet. Date of drilling - October 2, 1981. No groundwater encountered .

Figure 8-16 Log of Boring 12

B-16

I I File No. Cl-1088-Cl

I Table B-1

I SU1T111ary of Moisture, Density, Swe 11, Direct Shear and Unconfined Compression Testing

I Direct Shear (c) or Unconfined Compression (u)

I In-Place Conditions Swell Tests Testing

Unit Cohesion Dry Moisture Swell Moisture Angle of psf or

I Sample Density Content Index % Incre.ase Internal Unconfined Number Depth pcf % dry wt (A) Swell % (B) Friction psf

1-1 3' 110. 9 15. 1

I 1-2 8t' 102.5 22.5 0.2 0.2 0.9 26° 200 (c) 1-3 13!' 118. 5 13.2 1-4-1 18!' 112. 7 16.6 1-4-2 19t' 129.7 9.7

I 2-1 2' 111.7 12. 1 2-2 6' 114. 8 14. 5

I 2-3 12' 112. 7 17.2 2-4 19!' 123.8 12.7

I 3-1 2' 110.8 11.8 3-2 6' 108.5 18.5 3332 (u) 3-3-1 12' 108.8 18. 2 3-3-2 13' 112. 5 16. 1

I 3-4 18!' 132.0 6.3

4-1 3t' 114. 3 13. 6

I 4~2 8t' 92.2 29.6 4-3-1 13!' 82.0 38. l 4-3-2 14!' 84.8 36.6 4-4-1 18!' 90.8 28.9

I 4-4-2 19' 91.4 27. 4

5-1 2' 109. 2 14. 1

I 5-2 6' 112.4 17.6 0.9 12.0 13. 5 31° 0 (c) 5-3 12' 128.4 10.6

6-1 3!' 114. 3 14. 0

I 6-2 8!' 113. l 17.6 0.5 0.5 1.0 15° 800 (c) 6-3-1 13!' 120. 1 12.7 6-3-2 14' 129.6 10. 1

I I I B-17


File No. Cl-1088-Cl

Sample Nllllber De 2th

9-1 2' 9-2 6' 9-3 12!'

12- l 3i' 12-2-1 Bi' 12-2-2 9'

Table B-1 - continued

Sumnary of Moisture, Density, Swell, Direct Shear and Unconfined Compression Testing

Direct Shear (c) or Unconfined Compression (u)

In-Place Conditions Swell Tests Testin9 Unit Cohesion

Dry Moisture Swell Moi st,ure Angle of psf or Density Content Index % Increase Internal Unconfined

ECf % dr:i wt (A) Swell % (B) Friction psf

110. 7 17.5 1.0 4.3 4.2 29° 730 (c) 103.0 21.8 0. 1 0.2 1.7 23° 450 (c) 113. 2 17.9

104.2 21.0 3930 (u) 102.9 22.9 0. l 0. l 1.0 27° 150 (c) 108.8 19. 2

B-18


File No. Cl-l088"Cl

60

~o

)(

40 "' "' ;:;

30

~ <> t:;

20 .. it

10

0

0

Sample Numbnr

3-1

12-1

PLASTICITY CHART

/v CH v

/

~ v

~

CL / OH /

3-1 & 0/ 12-1 ,,,-;L MH

/ SM t sy ML

10 20 30 40 ~o 60 70 ·so ~o 100

LIQUID LIMIT~ %

At1erb11r51 Limitg

Oopth Liciuid Plasticity (II.) Oe:!lcriptlon Limit "lo In-

2 Grey-brown clayey SILT 33. 9 16

3i Grey-brown clayey SILT 33.6 16

B-19 Figure B-19


File No. Cl-1088-Cl

CONSOLIDATION CURVE

z 0

I- 4 1--1-...j....j..~j..j..j.l.j..j.j.j.11 <( 0 .J g 6 L.....J......L..J..J...J....l..L.U.I.""""'

z 0 u 8 1--1-...j....j..~j..j..j.l.j..j.j.j.11 .... 0

0.1 0.5 1.0 5 10

APPL! ED PRES SURE (in KIPS I tt• )

B-20

50 100

Figure B-20

-------------------

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-., ~-

"' c .... fl>

"' I

"' ~

DESCRIPTION: _L_i...::gc..h_t _b_r_ow_11_f_i_ne_s_a_11...;dy=--S_I_L T ______________ _

SAMPLE ~' 1-4-1 (Bari 119 l. at 181 feet) - U.S.

N910 too,.. ,

! ; : 1' ~ . . ..

100 50 10 5 .5 .I .05

GRAIN DIAMETER In MILL/METERS

COARSE FINE COARSE MEDIUM FINE COeBLES

GRAVEL SANO

JISTM-ASCE GIMIN $1.ZE SCALE"

GRAVEL

SAND

SILT

CLAY

.01 .005

SILT SIZES

FINES

0.0 °1. 30.0%

16.5 %

.OOI

CLAY SIZES

..., ~-~

fl>

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n ~

I ~

0

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DESCRIPTION: _L_i~g_h_t_b_r_o_wn_f_i_ne_s_a_n_dy_S_I_L T---------------

SAMPLE fll!;: 3-3-2 (Boring 3 at 6 feet)

0.0 °1. GRAVEL

SANO 38.0% 48.0% SILT

Sl ANOA RO SIEVE - U.S. SIZES -CLAY

J ' 4

-· 1.- -1

t . !~- t: r\1--' . ~--,,_

~- I • - ' 1 -" ; .. ' ~ ' - - - -. . . .

' -- i ~ I ~ f- ~ -i---- j j ~ . . - >- I . ._-.; ·- --'--

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100 50 JO 5 .5 . ( .05 .01 .005 .<Xll GRAIN OIAMHER In MILL IME TEllS

COARSE FINE COARSE MEDIUM FINE COBBLES

SILT SIZES CLAY SIZE s GRAVEL SANO FINES

ASTM-ASCE GRAIN SIZE SCALE


APPENDIX C

Suggested Grading Specifications

I I I I I I I I I I I -

I •


SUGGESTED GRADING SPECirICATIONS

PROJECT: FREMONT STATION, TYSON LANE

OWNER: MASLESA DEVELOPMENT

1.1 Introduction

1. 11 These Standard Grading Specifications have been prepared for the exclusive use of our client for specific application to the referenced project. These specifications have been prepared in accordance with generally accepted soil and foundation engineering practices; no other warranty, expressed or implied, is made.

1. 12 EARTH SYSTEMS CONSULTANTS, referred to as the Soil Engineer, shall be retained to provide continuous soil engineering services during construction of the grading, excavation and foundation phases of the work. This is to observe compliance with the design concepts, specifications and recommendations which will allow for design changes in the event that subsurface conditions differ from that anticipated prior to start of construction.

1.13 These specifications shall be integrated with the Soil Engineering Report of which they are a part. Should conflicting statements be found between these standard specifications and the itemized recommendations contained in the main body of the soil report, the latter shall govern.

1.14 The presence of our field representative will be for the purpose of providing observation and field testing. Our work does not include supervision or direction of the. actual work of the contractor, his employees or agents. The contractor for this project should be informed that neither the presence of our field representative nor the observation and testing by our firm shall excuse him in any way from defects discovered in his work. It is understood that our firm will not be responsible for job or site safety on this project. Job and site safety will be the sole responsibility of the contractor.

1.15 Where the contractor encounters subsurface conditions at the site that (a) are materially different from those indicated in the contract plans or in the specifications, or (b) could not have been reasonably anticipated as inherent in the work provided for in the contract, the contractor shall immediately notify the owner verbally and in writing within 24 hours. This notification shall be a condition precedent before any negotiations for "changed or differing site conditions" can proceed, If the owner determines that conditions do materially so differ to cause an increase or decrease in the contractor's cost of, or the time required

C-1

I I I I I I I I I I I I I I I I -..

File No. Cl-1088-Cl November 20, lg81

l • 16

l. 17

2. l

2. 11

2. 12

2. 13

3. l

3. 11

for, performance of any part of the work under this contract, then negotiations shall commence between owner and contractor to provide equitable adjustment to owner or contractor resulting therefrom.

The Soil Engineer shall be provided the opportunity for a general review of final design plans and specifications in order that earthwork and foundation recommendations may be properly interpreted and implemented in the design and specifications. (If the Soil Engineer is not accorded the privilege of making this recommended review, he can assume no responsibility for misinterpretation of his recommendations).

Whenever the words "supervision", "inspection", or "control" appear in the project specifications they shall mean periodic observation of the work and the taking of soil tests as deemed necessary by the Soil Engineer for substantial compliance with plans, specifications and design concepts.

General Description

These specifications shall apply to all clearing and grubbing, preparation of land to be filled, selection of suitable fill materials, filling of the land, spreading and compacting of the fill, installation of subdrains, construction of slopes, installation of utility trench backfill, and all subsidiary work necessary to complete the grading to conform with the lines, grades and slopes as shown on the accepted plans.

The standard tests used to define maximum densities of all compaction work shall be the ASTM Standard Test Method Dl557-70 or California Test 216. All densities shall be expressed as a relative compaction in terms of the maximum density obtained in the laboratory by one of the foregoing standard procedures.

The Soil Engineer shall be present at preconstruction meetings with the contractors representatives to review scheduling and the contractors scope of work. The Soil Engineer shall be notified at least 48 hours in advance of preconstruction meetings and grading operations so that he can coordinate his field personnel and dispatch them to the site when required.

Clearing, Grubbing and Preparation of Areas to be Filled

Existing strctures, foundations, trash, debris, loose fill, trees (not included in landscaping), roots, tree remains and other rubbish shall be removed, piled or otherwise disposed of so as to leave the areas that have been disturbed with a neat and finished appearance free from debris .

C-2



3. l 2

3. 13

3. 14

3. l 5

3. l 6

4. l

4.,,

4. 12

Septic tanks and other underground structures, where they exist on the site, must be totally removed, including all drain fields and connected lines, under the observation of the Soil Engineer. Depressions left from any removals shall be properly filled and compacted in accordance with these specifications.

The methods for removal of subsurface irrigation and utility lines will depend on the depth and location of the line. One of the following methods may be used: l) Remove the pipe and compact the soil in the trench according to the applicable portions of these recommendations; 2) The pipe shall be crushed in the trench. The trench shall then be filled, compacted according to the applicable portions of these grading specifications; 3) Cap the ends of the line with concrete to mitigate entrance of water. The length of the cap shall not be less than 5 feet. The concrete mix shall have a mi.nimum shrinkage.

Abandoned water wells, where encountered on the site, shall be capped according to the requirements of the appropriate regulatory agency. The strength of the cap shall be at least equal to the adjacent soil. The final elevation of the top of the well casing shall be a minimum of 36 inches below any adjacent grade prior to any grading or fill operations. Structure foundations shall not be placed over the capped well.

Organic matter shall be removed from the surface upon which the fil 1, foundations or pavement sections are to be placed. The surface shall then be plowed or scarified to a depth of at least 8 inches and until the surface is free from ruts, hummocks or other uneven features which would tend to prevent uniform compaction by the equipment to be used. Specific recommendations pertaining to stripping, minimum depth of recompaction and requirements for additional subexcavation of native soils are presented in the main body of the soil report.

Where identified in the body of the soil report alluvial and colluvial soil sha 11 be removed from the draws to expose weathered "bedrock" or other competent material. The excavated soil from the draws may be mixed with other soil and rock materials from the cut areas for use in compacted fills.

Materials

Native soil free of organic material and undesirable deleterious material may be used as compacted fill. During grading operations the Soil Engineer will re-examine the soil for organic content. Excavated rock materials from the site may also be used as compacted fill, provided the rock fragments are not too large to allow uniform compaction.

The materials for compacted fill shall be examined and tested by the Soil Engineer for conformance with these specifications during grading

C-3



4. 13

5. 1

5. 11

5. 12

s. 13

5. 14

5. 15

operations. Imported material must be approved for use before being brought to the site. The materials used shall be free from vegetable matter, oversized rock, and other deleterious material.

Oversized rock (larger than 12 inches) which cannot be placed in fills as described in Section 5.12, shall be disposed of offsite.

Placing, Spreading and Compacting Fill Material

The selected fill material shall be placed in layers which can be compacted satisfactorily with the equipment being used. Each layer shall be spread evenly and shall be thoroughly blade-mixed during the spreading to provide uniformity of material in each layer.

Rocks larger than 6 inches in diameter may be permitted in the compacted fill with review as to location by the Soil Engineer. This section of the specifications is generally applicable to rock placement. Rocks larger than 6 inches will not be permitted in the final 2 feet of fill on the building pads. No rocks larger than 12 inches will be permitted in areas and to depths of planned trench excavations. The maximum size of rock permitted in the remainder of the fill will depend on the ability of the compacting equipment to achieve a properly compacted uniform fill. Generally, rocks larger than 12 inches should be segregated and spaced to a.llow placement and compaction of finer materials around the rocks. Oversized rocks (larger than 12 inches) should be placed in the deeper fill areas, or disposed of outside the limits of grading. Rocks shall not be nested and all voids must be filled and compacted.

When the moisture content of the fill material is below that sufficient to achieve desired compaction, water shall be added until the moisture content is as specified to assure thorough bonding during the compacting process. When the moisture content of the fill material is excessive, the fill material shall be aerated by blading or other satisfactory methods until the moisture content is as specified.

After each layer has been placed, mixed and spread evenly, it shall be thoroughly compacted. Unless specifically modified in the body of the soil report the compaction shall be to a minimum relative compaction of 90%, except for the upper 18 inches of subgrade in streets, which shall be to 95%. ·

Compaction shall be by sheepsfoot rollers, multiple-wheel pneumatictired rollers or other types of acceptable compaction rollers. Rollers shall be of such design that they will be able to break down the rock materials, and compact the fill to the specified compaction. Rolling sha 11 be accomplished while the fi 11 material is at the approximate optimum or other specified moisture content. Rolling of each layer shall consist of sufficient passes to achieve the specified compaction.



5. 16

5. 17

5. 18

6. 1

6. 11

6. 12

6. 13

6. 14

6. 15

Field density tests will be performed by the Soil Engineer during placement of the compacted fill. Where sheepsfoot rollers are used, the soil may be disturbed to a depth of several inches. Density tests shall be taken in compacted material below the disturbed surface. When these tests indicate that the density of any layer of fill or portion thereof is below the required compaction, the particular layer or portion shall be reworked until the required density has been obtained.

The fill operation shall be continued in 6 inch compacted layers, as specified above, until the fil 1 has been brought up to the finished slopes and grades as shown on the accepted plans.

Earth moving and working operations shall be controlled to prevent water from running into excavated areas. Ponded water shall be promptly removed and the site kept at a workable moisture content.

Subdrains

Subdrains shall be placed as recommended by the Soil Engineer in the field and shall consist of approved pipes and approved filter material as specified in the current edition of California Standard Specifications (Ca ltrans).

Permeable material for use in backfilling trenches under, around or over subdrains and permeable material for blankets or other subdrainage purposes shall consist of hard, durable clean sand, gravel or crushed stone and shall be free from organic matter, clay balls, or other deleterious substances. It shall consist of aggregate meeting California Standard Specifications for Class 2 Permeable Material (Section 68). Other materials may be used if approved by the Soil Engineer after appropriate testing.

Trenches for subdrains shall be excavated to a width equal to the outside diameter of the perforated pipe plus 1 foot and to a depth established by the Soil Engineer. The bottom of the trench shall then be covered full width by 4 inches minimum of specified filter material and the drain pipe laid with perforations at the bottom. The pipe sections shall be joined by suitable couplers. Subdrain pipes shall be installed with a minimum slope of 2%, discharged into positive drainage devices.

Unless otherwise recommended, the following minimum pipe diameters shall be used: Laterals up to 50 feet in length - 4 inches; and Laterals over 50 feet in length and Main Subdrains - 6 inches.

After the pipe has been placed, the subdrain pipe shall be covered with filter material to a minimum of 2 feet over the top of the pipe. The material shall then be covered for the full width of the trench or blanket by compacted fill material.

C-5

I I I I I I I I I I I I I I I I

• -


7.1 Slope Construction (NOT APPLICABLE)

s. l

8. 11

8. 12

8. 13

8. 14

8. 15

8. 16

Trench Backfill

Materials for trench backfill shall consist of: soil and rock materials from the excavation, free of organics and other deleterious substances, and free from rocks larger than 6 inches in greatest dimension; imported sand; crushed rock or gravel; or imported soil previously tested by the Soil Engineer. The approved backfill materials shall be used in those portions of the trenches described below.

Backfill for bedding and initial backfill (minimum depth of 12 inches over the pipes) shall consist of imported sand or crushed materials ("quarry fines") free from clay or organic material. The material shall be well graded of such size that 90 to 100% will pass a No. 4 sieve, and not more than 5% will pass a No. 200 sieve. Stones or rock fragments larger than 2 inches will not be permitted in the bedding and initial backfi 11.

Subsequent backfill, defined as the backfill overlying initial backfill and extending to within 18 inches of subgrade elevation shall consist of either approved onsite excavation, or approved granular import material. Subsequent backfill shall be free from organics and other deleterious substances, and be of such as size (gradation) to allow uniform compaction to the specified relative compaction. Rocks larger than 6 inches in greatest dimension will not be permitted as subsequent backf i 11.

The final 18 inches of backfill (measured from subgrade elevation) in pavement areas shall consist of onsite clayey soils, or imported clayey soils, to provide a relatively impermeable cap over the underlying trench backfill. The final backfill shall be free from organics and other deleterious substances, and shall contain no rock fragments larger than 2 inches. The material shal 1 be uniformly blended to allow compaction to the specified density (relative compaction).

Trench backfill in street or paved areas unless specifically modified in the body of the soil report or by the appropriate local jurisdiction shall be compacted to at least 85% relative compaction to within 6 feet of subgrade elevation and to at least 90% relative compaction to within 18 inches of subgrade elevation. The uppermost 18 inches of backfill, measured from subgrade elevation, shall be compacted to a minimum relative compaction of 95%.

Trench backfill in lot areas, but not in street or paved areas, shall be compacted to a minimum relative compaction of 90% to the surface of the surrounding ground. Trench backfill outside lot areas, and not in street

C-6



or paved areas, shall be compacted to a minimum relative compaction of 85% to the surface of the surrounding ground.

8. 17 It is the intent of these specifications that utility trench backfill be mechanically compacted. Jetting may be permissible where subdrains are included within the trench to discharge excess water, and the backfill materials have a Sand Equivalent of 20 or greater. The Soil Engineer sha 11 make subsequent recommendations on the use of Jetting based on field conditions exposed during excavation of the trenches and on further testing of backfill materials.

8. 18 Groundwater entering trenches at the time of excavation shall be removed by positive and permanent means to a controlled outlet as recommended by the Soil Engineer.

8.19 The Soil Engineer will observe and periodically test the backfill during the underground construction to assess that the work was constructed in essential compliance with these specifications.

9.1 Seasonal Limits

9. ll Fill material shall not be placed, spread or rolled during unfavorable weather conditions. When the work is interrupted by heavy rain, fill operations shall not be resumed until field tests by the Soil Engineer indicate that the moisture content and density of the fill are as previously specified.

10. 1 Unusual Conditions

10.11 In the event that unusual conditions not covered by these specifications are encountered during grading operations, the Soil Engineer shall be immediately notified for evaluation and recommendations.

C-7

·:1 FILE NO. Cl-1088-Cl

•• I I I I I I I I I I I I I I I I I

Existing Tract 3778

Exi stinq l O' Easement

5 6 s 7 - 5 e. ~

-~~~--:...~~~~~~- 59 ~ ---~:------

" r- r--1 f1 r-1 LJ I I I

I I I

I -..J

Existing _ 5 Dirt Road

57

Ill Building Restriction Zone

~ Fault Set Back Zone

~ Existing Structures

r~ .._J Proposed Structures

r-1 r--1 I I L1 , I I I I I l I I I 1 I r, I I ._ _ _J lJ L J _ __,

59

58

c.::J Existing Trees

~ T:-ench Locations·

~ Boring Locations

" Fault Trace -...__.

8

6

J 1 ri r---1 I I LJ I I I I I I I I I I . I f 1 I I L _ _, L.J L _J

I I

0 30 60 H ...,

Seale in Feet

I I I I

61

61

62

SITE PLAN Fremont Station Project

Tyson Lane,.Fremont, California

Pl ate I

san francisco district office ~~ p- i...

Documents