Appendix D-3 Supplemental Fault Ground Rupture

Appendix D-3

Supplemental Fault Ground Rupture

SOIL ENGINEERS ENGINEERING GEOLOGISTS 5587 SUNOL BOULEVARD PLEASANTON, CA 94566 (925) 484-0220 FAX: (925) 846-964

Via E-Mail

January 6, 2017

BSA Job No. 3823.100

Mr. Kyle Masters

The Grupe Company

3255 West March Lane

Stockton, California 95219

Subject: Supplemental Fault Ground-Rupture Investigation

Ersted Property

APN: 078C-0461-001-13

Hayward, California

Dear Mr. Masters:

Berlogar Stevens & Associates (BSA) is pleased to present this Supplemental Fault Ground-

Rupture Investigation report for a portion of the Ersted property in Hayward, California. The

scope of services conducted during the course of this investigation, our findings and our

recommendations for modification of the previously identified “Development Zone” in the lower

portion of the site are presented below.

Several previous site investigations identified faults considered to be active crossing the Ersted

property, as shown on Plate 2. The presence of these faults reduced the area of potential

property development. Engeo (Engeo 2005 and 2007) identified two “Tentative Residential

Structure Development Zones.” The upper or more northeasterly of the two zones was modified

by Makdissy in 2013. Makdissy adopted the lower or more southwesterly zone as mapped by

Engeo. The lower zone, which covers an area of about 4 acres, has not been shown to be crossed

by active faults and is the subject of this report. It is our understanding that The Grupe

Company’s interest in development of the site is limited to the previously identified lower

development zone; there are no plans for development the upper portion of the site at this time.

Thus, our investigation for potential fault ground rupture was limited to the area southwest of

Fault 2 as mapped by Engeo and shown on the Site Plan, Plate 3. This area will be referred to in

this report as the “Study Area.” The USGS quadrangle shows the coordinates of a point near its

approximate center of the Study Area are latitude: 37.6355 N and longitude: 122.0500 W.

SITE DESCRIPTION

The southwest sloping Ersted property lies on the west flank of the East Bay Hills about six

miles northeast of the San Francisco Bay. The approximately 15½-acre, roughly triangular-

shaped property (Assessor’s Parcel Number 078C-0461-001-13) is located about 450 feet east of

Mission Boulevard and south of the La Vista Quarry in Hayward (Vicinity Map, Plate 1). The

parcel is about 1,500 feet deep and is elongated in a northeastern direction, narrowing toward the

BERLOGAR

STEVENS &

ASSOCIATES

January 6, 2017


Page 2

BERLOGAR STEVENS & ASSOCIATES

northeast. The United States Geologic Survey 7½-minute Hayward quadrangle topographic map

(USGS, 1980) indicates that the property ranges from an elevation of about 50 feet above mean-

sea-level (msl) in its southern corner to about 265 feet in its northwestern corner. Existing

vegetation is predominantly seasonal grasses with a few scattered palm and willow trees. A

linear stand of eucalyptus trees is located along the southwestern property line.

PURPOSE AND SCOPE

The purpose of this investigation is to further characterize the geologic conditions of the lower,

southwestern part of the Ersted property, specifically with respect to potential ground rupture

from active fault displacement. Evaluation of seismic shaking, discussion of other geologic

hazards, and geotechnical design considerations and parameters will need to be addressed in a

subsequent geotechnical investigation of the site.

Our investigation included the following:

Review of readily available published and unpublished geologic maps and documents

relating to the site and vicinity.

Examination of historical topographic maps, aerial photographs; and LiDAR images of

the site and vicinity.

Reconnaissance of the site and surrounding area to observe surface geologic conditions.

Contacting the City of Hayward’s consulting geologist, Mr. Lou Richardson, to briefly

discuss the site and our proposed study, and to schedule the consulting geologist for

observation of our trenches along with periodic review of our trench logging.

Mark the field exploration locations and contacting USA.

Exploration of subsurface conditions by excavating and logging six exploratory trenches.

The trenches were excavated in two phases with Trenches T-1 through T-5 excavated

during our initial phase of field exploration and an additional trench, T-6, excavated after

review of the first phase data and additional data received for a study conducted on an

adjoining site.

Preparation and submittal of a Work Plan to the City of Hayward for approval prior to

conducting the second phase of our field exploration program.

Backfilling of the trenches with the trench spoils. The backfill was placed as

uncontrolled fill and will need to be re-excavated and then replaced as engineered fill

during future grading activities.

Consultation with The Grupe Company (Grupe) during the field exploration and report

preparation phases.

Review and discussion of our findings with Mr. Lou Richardson, C.E.G., acting as peer

reviewer for the City of Hayward.

January 6, 2017


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Analysis of geologic data from researched documents and collected field data to develop

conclusions and recommendations for the Study Area regarding potential earthquake

ground rupture.

Preparation of this report presenting our findings and recommendations.

REGIONAL GEOLOGY

The City of Hayward and the Ersted property are located within the Coast Ranges Geomorphic

Provinces. The province consists of a series of discontinuous northwest trending mountain

ranges, ridges, and intervening valleys characterized by complex folding and faulting. The

general geologic framework of the area is illustrated in studies by Schlocker (1970), Dibblee

(1980), Wagner and others (1991), Chin and others (1993), Ellen and Wentworth (1995), and

Helley and Graymer (1997), Graymer (1995), the California Geological Survey (CGS, 2002),

among others. A summary of compiled regional geologic mapping is presented on Plate 4,

Regional Geologic Map.

Geologic and geomorphic structures within the San Francisco Bay Area are dominated by the

San Andreas fault system, a right-lateral strike-slip transform boundary that extends from the

Gulf of California in Mexico, to Cape Mendocino in Humboldt County, California. It forms a

portion of the boundary between two independent tectonic plates. To the west of the San

Andreas fault system is the Pacific plate, which moves north relative to the North American

plate, located east of the fault system. In northern California, movement across this plate

boundary is concentrated on the San Andreas fault. However, a portion of the movement is also

distributed across a number of faults including the Calaveras, Hayward, San Gregorio, Paicines,

Zayante-Vergeles, and Quien Sabe among others. Together, these faults are referred to as the

San Andreas fault system. Movement along this fault system has been ongoing for about the last

25 million years. The northwest trend of the faults within this system is largely responsible for

the strong northwest/southeast structural grain of geologic and geomorphic features along coastal

California and the San Francisco Bay Area.

Basement rocks east of the San Andreas fault system consist of a chaotic mixture of highly

deformed marine sedimentary, submarine volcanic and metamorphic rocks of the Franciscan

Complex of Jurassic to Cretaceous age (205-65 million years old). West of the San Andreas

fault system the basement rocks consist of successive slivers of granite once associated with the

Sierra Nevada - Peninsular intrusive complex (batholith) but which have been sliced by the San

Andreas fault and "stretched out" to the northwest to their current position.

FAULTING

The project site is located in an area characterized by moderate to high seismic activity. Plate 6,

Fault Activity Map, shows faults and their inferred activity in the vicinity of the project site. An

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active fault is a fault that has experienced seismic activity during historic time (since roughly

1800 A.D.) or exhibits evidence of surface displacement during Holocene time (latest 11,700

years) (Hart and Bryant, 2007) and is therefore considered more likely than older faults to cause

ground rupture. Two significant aspects of fault activity that can damage buildings and

infrastructure are ground rupture along active earthquake-fault traces and seismic shaking. This

present study is limited to evaluation of ground rupture only. Seismic shaking will be addressed

in a later design-level geotechnical investigation report.

AREA AND SITE GEOLOGY

Approximately two-thirds of the northeast part of the Ersted property is located within a State of

California Earthquake Fault Hazard Zone (CGS, 1982) for the Hayward fault as shown on the

Earthquake Fault Hazard Zone Map (Plate 7). The main trace of the Hayward fault is mapped to

cross the Ersted parcel near the property’s eastern property line (California Geological Survey,

CGS, 1982; Graymer, 1995; Crane, 1988; Dibblee, 1980; Radbruch-Hall, 1974; Herd, 1978;

Lienkaemper, 2006) about 750 feet northeast of the Study Area. The current Study Area is not

within and is southwest of the state designated Fault Hazard Zone. However, previous geologic

investigations indicate the presence of several fault traces south of the hazard zone (Site Plan).

The presence of active faults south of the state’s Fault Hazard Zone gives reason for a subsurface

investigation in the southwest portion of the Ersted property prior to site development.

The Ersted Study Area is underlain by basement rock consisting of a complicated mixture of

metamorphosed rocks of the Franciscan Complex derived from deformed and accreted seafloor

rocks. Structurally adjacent to or unconformably overlying the Franciscan are marine

sedimentary rocks of the Great Valley Group deposited during Jurassic and Cretaceous time.

The Great Valley Group in the Study Area is mantled by alluvial fan and colluvial materials shed

from the hills to the east. Mapping by Graymer and others (1995) of the USGS indicates that the

Study Area is underlain by the Jurassic Age Knoxville Formation of the Great Valley Group

(JKkc on the Vicinity Geologic Map, Plate 5). Graymer and others describe the Knoxville

Formation as mainly dark, greenish-gray silt or clay shale with thin sandstone interbeds. Locally

the formation includes thick pebble to cobble conglomerate beds in its lower part (JKkc) and

beds of angular, volcanoclastic breccia derived from underlying ophiolite and silicic volcanic

rocks.

PREVIOUS EXPLORATORY TRENCHING

The general northeast and southwest boundaries of the current Study Area within the Ersted

property were established based on the presence of faults found in trenches excavated by Engeo

(2005). In the north, Engeo’s trenches ET-1, and ET-2 exposed a series of faults in a fault zone

about 50 feet wide striking about N85°E to N65°W and shown on trench log of ET-1 to dip

about 29°N to 60°N. This fault zone is labeled Fault 2 on Engeo’s Site Plan, included as Plate 2,

and on our Site Plan, Plate 3. To the south, Engeo’s trenches ET-1, and ET-3 exposed two

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additional faults with strikes about N40°W (Faults 3 and 4, Plate 2). Engeo’s site plan shows the

dips of these faults to vary between 21°N and 36°N. However, these dips correlate in the trench

log with the faults’ attitudes near the ground surface where they appear to be distorted or bent

over by near surface soil creep. The log of trench ET-3 shows the dip of Fault 3 near the bottom

of the trench to be about 75°N. This difference in dip suggests that the faults’ ground-surface

intercept in the southeast part of the Study Area would be further downslope to the southwest

than the uncertain fault locations shown on Engeo’s site plan (dashed and queried lines, Engeo

Site Plan, Plate 2). Furthermore, the strikes recorded by Engeo indicate the faults should trend in

an east-southeast to southeasterly direction, not easterly as shown by Engeo. The queried

locations of Faults 3 and 4 are not supported by the strikes and dips of the faults as logged by

Engeo. Engeo’s Faults 2, 3 and 4 are interpreted to be splays off of the Hayward fault and

probably merge with the main trace laterally and at depth. In addition to the faults discussed

above, Engeo’s logs of ET-1 ET-3 show the presence of shears in material below the upper soil

layers. Numerous shears within the Franciscan Complex were mapped with strikes ranging from

N15ºW to N60ºW with dips between 23ºNE to 54ºNE.

The California Department of Mines and Geology1 1981 Fault Evaluation Report (FER) No. 103

states that south of the mapped trace of the Hayward fault the “consulting reports in the Hayward

quadrangle tend to present a confusing picture.” The FER describes a Judd Hull & Associates

(JHA, Alquist-Priolo number AP No. 200, 1975) trench on property adjacent to and southeast of

the Study Area (Site Plan) where a fault gouge zone was detected in one trench but not in another

nearby trench. The FER reports that JHA did, however, establish a setback from the fault gouge.

The fault identified by JHA southeast of the Study Area approximately correlates with Engeo’s

Fault 4 when the fault outcrop pattern is corrected to the fault’s dip at the bottom of the trench.

HISTORICAL TOPOGRAPHIC MAP AND AERIAL PHOTOGRAPHIC REVIEW

We reviewed readily available topographic maps and aerial photographs of the area to evaluate

historical surface features that may relate to fault locations and areas of past fault deformation.

The years covered by the topographic maps and aerial photographs reviewed for this study are

listed in the tables included as an attachment.

The 1899 and subsequent 15- and 7½-minute topographic quadrangles show a roadway leading

from Mission Boulevard upslope to the current Ersted property. Several structures are shown on

the 1899 and 1915 maps scattered around the slope, but none on the Ersted property. Most of the

structures do not have roads to them and therefore may be barns or other outbuildings. The 1941

and later topographic maps do not show the structures. The 1959 7½-minute Hayward

quadrangle is the first to show symbols of a quarry north of the current Ersted property and to

show an elevation benchmark near the property’s west property line. The 1968 quadrangle

1 California Geological Survey, CGS, was formerly known as the California Department of Mines and Geology until its name

change in 2006.

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shows a large excavated pit in the upper, narrow part of the Ersted property that is not shown on

the 1959 or earlier maps. No local lineations or other features suggestive of faulting were

observed on the topographic maps.

The series of aerial photographs reviewed show seasonal vegetation changes and variation of

trails and show that cultural changes such as permanent roads or structures have not been made

on the property during this period. The photographs were studied for the presence of features

characteristic of fault traces such as linear discontinuities in rock or soil, offset watercourses,

linear scarps, topographic lows, vegetation patterns or breaks in slope. The photographs show

that Engeo’s Trenches ET-1 and ET-3 were excavated between December 21, 2004 and June 11,

2005. No tonal changes within the Study Area possibly resulting from fault deformation are

observed in the aerial photographs.

LiDAR images of one-meter resolution, bare earth hill-shades topography dataset provided by

Northern California GeoEarthScope (KMZ Google Earth file) were examined for shadow

features that may be associated with ground deformation related to faulting. The hillshades 45°

sun-angle image that covers the Study Area suggests a topographic shadow lineation along a

similar local trend of the Hayward fault, which is located northeast of the Study Area. The

lineation, expressed as southwest-facing topographic shadows, is observed about 450 feet south

of the Study Area trending about N35°W through the headscarp of a landslide adjacent to the

property’s southeast property line. The feature is not observed on the ground surface in the

LiDAR image within the Study Area possibly due to ground modification caused by downslope

soil creep. The shadow feature is observed as far as about 800 feet northwest of the Study Area

along approximately the same trend observed southeast of the Study Area. Other strong

lineation features are observed north of the Study Area in the vicinity of the mapped trace of the

Hayward fault.

SITE RECONNAISSANCE

A Certified Engineering Geologist (C.E.G.) representing BSA performed reconnaissance of the

site and surrounding vicinity on several occasions between November 2 and December 19, 2016

to observe surface conditions that may relate to fault ground rupture. The Study Area and parts

of adjacent properties were walked to observe possible evidence of surface disturbance from

faulting. The property north of the Study Area has recently been graded to construct a roadway

accessing a new subdivision east of the Ersted property. The earthwork for the roadway has

obscured possible evidence of faulting. The landslide scarp south of the Study Area noted in the

LiDAR discussion above was observed in the field to align generally parallel with the local strike

of the Hayward fault. No ground-surface evidence of fault activity affecting the Study Area was

observed during our site reconnaissance.

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BSA EXPLORATORY TRENCHES

Six exploratory trenches were excavated and logged in the Ersted Study Area to explore for the

possible presence or absence of potentially ground-rupturing faults, possibly associated with

shears logged by Engeo in their trench ET-1, between Engeo’s Faults 2 and 4, as well as to

investigate the queried Faults 3 and 4, projected eastward from the faults logged by Engeo in

their trench ET-1, in the vicinity of the southeast property line. During excavation and logging

of the exploratory trenches, Mr. Lou Richardson, C.E.G., representing the City of Hayward as

the peer reviewer, was present periodically to review our findings in the trenches as they were

logged. At completion of logging, the ends of the trenches and fault traces encountered in the

trenches were staked and surveyed for plotting as shown on the Site Plan, Plate 3. The trenches

were backfilled and nominally compacted with the excavator bucket. Trench T-6 was covered

with straw blankets to reduce erosion potential.

TRENCH T-1

Exploratory Trench T-1 (Log of Trench T-1, Plate 8) was located northeast of Engeo’s Trench

ET-1 to further explore for the possible presence of fault displacement within the Study Area and

to evaluate the character of the shears previously encountered in the area. The 380-foot long

trench was laid out along a trend of N62°E and cut through the fill berm near the north part of the

Study Area. Beneath the black clayey colluvial soil of up to about 2½ feet thick, bedrock of the

Knoxville Formation was encountered. The Knoxville Formation represented in the trench

consists of discontinuous and deformed beds of shale, claystone containing completely

weathered sandstone cobbles, serpentinized lithic fragments, and volcanic breccia. According to

published reports by the USGS (Graymer, 1995), this material is associated with the lower

section of the Knoxville Formation and is derived in part from the underlying ophiolite deposits.

Between about Station 0+50 and 0+56, a 6- to 12-inch thick white calcareous fault-gouge vein

(attitude of N50°W52°N) was encountered near the bottom of the trench. Bedrock materials

north and south of the fault are distinctly different (Log of Trench T-1). The fault extends

upward into the overlying colluvial soil where soil creep has bent and stretched the fault material

downslope.

Six prominent shear planes were mapped in Trench T-1. The shears deform, and are entirely

within, the Knoxville Formation beds (described as Franciscan mélange in the Engeo trench) and

do not extend into or affect overlying soils. As opposed to the fault in Trench T-1 near Station

0+50 that dips to the north, the shears dip to the south with attitudes of N20°-25°W50°-59°S.

The shears encountered in Trench T-1 do not align along strike with or project to the shears

mapped in Engeo’s Trench ET-1, which differ in dip direction from those in T-1. The shears

observed in Trench T-1 and Engeo’s ET-1 are therefore interpreted to be discontinuous, localized

features. In addition, because of their non-congruous attitudes with local fault traces, the shears

appear to be related to compressional history not associated with Hayward fault displacement.

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TRENCH T-2

Trench T-2 was positioned near the northwest corner of the Study Area to explore for the

possible presence of faulting west of the projected north alignment of Engeo’s Fault 2 (Site

Plan). The 197-foot long trench, laid out along a trend of N68°E, was excavated to a depth of

about 6 feet. Beneath the dark gray gravelly, clayey colluvial soil up to about 2 feet thick,

bedrock of Knoxville Formation conglomerate was encountered. The bedrock consists of well-

rounded fine-grained sandstone in a hard clay matrix. A depositional channel consisting of loose

to dense, clast supported sandy gravel was located between Stations 0+30 and 0+40. Well

indurated but closely to widely fractured siltstone beds were exposed northwest of Station 0+70.

Depositional contacts observed in the trench range from sharp to gradational. No evidence of

fault displacement was found in the trench.

TRENCH T-3

A third exploratory trench (Trench T-3) was positioned near the Ersted property line in the

southeast portion of the Study Area to investigate the possible continuation of Engeo’s uncertain

(dashed and queried) Faults 3 and 4, and possible presence of shears. The 155-foot long trench,

laid out along a trend of N3°E, was excavated to a depth of about 11 feet. Beneath the black silty

clay colluvial soil (up to about 6 feet thick near the trench’s north end), claystone of the

Knoxville Formation was encountered. Contacts observed in the trench range from sharp to

gradational deposition. Deformation of the Knoxville Formation by shearing was not observed

in the trench. No evidence of fault displacement was found in the trench.

TRENCHES T-4 and T-5

Two short offset Trenches T-4 and T-5 were located about 35 feet north and south, respectively,

of Trench T-1 in order to measure the trend of the fault observed in T-1. The trenches were

about 35 feet long and up to about 5½ to 6 feet deep. Approximately the same fault

configuration was found in these two trenches as was seen in Trench T-1 (Log of Trenches, Plate

8). The fault near the base of the trenches is about 6- to 12-inches thick consisting of white

calcareous gouge. As the fault nears the overlying colluvial soil, it is bent, stretched and pinches

out downslope.

TRENCH T-6

Because the dashed and queried Engeo Faults 3 and 4 were found not to be present in Trench T-

3, Trench T-6 was positioned to evaluate if the fault found in Trenches T-1, T-4 and T-5 passes

south of Trench T-3. The north end of Trench T-6 was located about 150 feet west of T-3 and

was excavated in a southerly direction for about 145 feet in an attempt to define the most

northern extent of the fault. Between trench Stations 0+40 and 0+48, a 6- to 12-inch thick

calcareous fault vein with an attitude of N65°W60°N was encountered (Log of Trench T-6, Plate

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8). Bedrock materials north and south of the fault are distinctly different (Log of Trench T-6).

The structural pattern of the fault in Trench T-6 matches the configuration of the fault observed

in Trenches T-1, T-4, and T-5. As the fault approaches the overlying colluvial soil, it is bent,

stretched and pinches out downslope. A subtle change in ground-surface slope with the

northeast side up is present above an apparent vertical fault offset of the colluvial soil/bedrock

contact about 4 feet below the surface (Log of Trench T-6).

About 50 feet southeast of the south end of Trench T-6, there is a landslide in the over-steepened

cut slope on adjacent property. The landslide was observed in the field and on LiDAR images.

The headscarp of the landslide is approximately along strike of the fault mapped in Trench T-6.

The landslide may have failed along the weak fault plane, although no surface features indicative

of a fault were observed in the area.

APPLICABLE FAULT-SPLAY MECHANICS

Because the faults found near and within the Ersted Study Area trend sub-parallel to the

Hayward fault and dip back into the hillside toward the Hayward, they are considered splays

from the main trace and are, therefore, not primary areas of ground rupture. Splay faults form

when the primary fault becomes critically misaligned with the principal stresses such that splay

fault formation, on the optimum plane of faulting, is favored (Scholz and others, 2009). Splay

faults form sequentially away from the principal fault trace so that subsequent and further away

traces exhibit successively reduced slip. Splay faults do not always rupture during an earthquake

on the primary fault (USGS, Wald, https://earthquake.usgs.gov/research/splays/splays.php) and

when they do it is only in response to, and with lesser slip displacement than, movement on the

principal fault plane.

CONCLUSIONS AND RECOMMENDATIONS

The following observations and conclusions are derived from our research and field exploration

for the specified Study Area of the Ersted property. Our study area was limited to the previously

identified Development Zone southwest of Engeo’s Fault 2, and includes portions of the site

crossed by the uncertain (queried) locations of Engeo’s Faults 3 and 4.

BSA Trench T-1 was excavated across the Study Area to explore the possibility that shears

logged by Engeo in their trenches ET-1 and ET-3 may or may not be active faults. Because the

shears are structurally different in both strike and dip from the splay fault encountered in Trench

T-1 and do not correlate from one trench to another, they appear to be unrelated to active faulting

but appear to be related to deformation history not associated with Hayward fault displacement.

Consequently, in our opinion these features are not active faults and do not require setbacks for

structures. As mentioned above, we encountered a fault in Trench T-1. The continuation of fault

trace was verified and the fault orientation (strike and dip) were confirmed with the excavation

of Trenches T-4 and T-5.

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Given Engeo’s uncertain (queried and dashed) projection of Fault 2 in the northwest portion of

the Development Zone, BSA’s Trench T-2 was excavated southwest of queried Fault 2 to check

for the presence or absence of faulting. There was no evidence of faulting exposed in Trench T-

2.

BSA Trench T-3 was excavated across Engeo’s uncertain (queried and dashed) Faults 3 and 4.

No evidence of fault displacement was found in the trench. Furthermore, there was no evidence

of deformation of the Knoxville Formation by shearing in the trench, which is further evidence

that shears in Trenches T-1 are not continuous across the site and are not associated with active

faulting.

To resolve the issue of the unsupported and questioned fault projections by Engeo through the

area of BSA Trench T-3 (fault traces which are not present in T-3) and to investigate where the

fault identified in Trenches T-1, T-4 and T-5 extends to, BSA Trench T-6 was excavated

between Engeo Trench ET-1 and BSA Trench T-3. A fault interpreted to be the continuation of

the fault observed in Trenches T-1, T-4, T-5, and ET-1 was exposed in Trench T-6. This fault

aligns with the strikes and dips of the three BSA trench (T-1, T-4 and T-5) exposures and with

corrected projections of fault trends based on the strike and dips in Engeo’s Trench ET-1.

Trench exploration carried out in this current BSA investigation revealed a fault within the Study

Area. The fault passes through Trench T-1 near Station 0+50, and through Trench T-6 near

Station 0+48 following a general trend of N60°W with a dip of about 60°N. This trend is

consistent with the strikes shown by Engeo for faults logged at their trenches ET-1 and ET-3 and

consistent with the fault dips near the bottom of Engeo’s Trenches. Given: 1) the similarity in

fault’s strike in Trenches T-1, ET-1 and T-3, and 2) the absence of faulting in Trench T-3, it is

our opinion that the queried Faults 3 and 4 are not present at the locations shown by Engeo east

of their trench ET-1. It is our opinion, based on fault exposures in the trenches, that the fault we

encountered corresponds to Engeo’s Fault 3 in Trench ET-1. Instead of projecting toward

Trench T-3 as shown by Engeo, the fault continues along strike downslope to the southeast as

depicted on the Site Plan.

The fault identified in this study and Fault 2 in the Engeo report are steeply dipping splays from

the Hayward. Because of the steep dip exhibited by the faults (greater than 45°), they are not

thrusts as suggested by the fault symbols displayed on the Engeo Site Plan. These splay faults

are not independent sources of ground deformation but they may exhibit displacement in the

event of fault rupture on the Hayward. However, because the traces are splays, they would be

expected to produce less movement than on the primary fault trace located about 750 feet to the

northeast. Considering the above discussion, we recommend a setback of 25 feet for future

structures intended for human occupancy from the mapped splay trace observed in BSA

Trenches T-1, T-4, T-5 and T-6 as shown on the Site Plan.

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The shears described in the Engeo trench logs and encountered in Trenches T-1 and T-6 of this

investigation are found not to be continuous across the Study Area and therefore are interpreted

not to be active faults. Although no setbacks from the shears are needed, it is recommended that

that foundations within the Study Area be designed to accommodate expected earth deformation

caused by an earthquake on the Hayward or other nearby Bay Area faults. The design-level

geotechnical report should include design recommendation for structural foundations in

accordance with the expected fault-related deformation.

With consideration of the work by others as discussed above, and the data collected by BSA

though the course of this investigation, we have delineated a revised Development Zone for the

southwest portion of the site. The revised zone is based on the previously established 50-foot

setback from Fault 2 as identified by Engeo and the recommended 25-foot setback from the fault

trace identified in our trenches. The modified Development Zone is shown on the Site Plan,

Plate 3.

LIMITATIONS

This study was conducted for due diligence purposes for faulting and does not constitute a

comprehensive geologic and geotechnical investigation of the site. Prior to development of the

Study Area, a geologic hazard evaluation addressing slope stability, other geologic site

conditions and a design-level geotechnical investigation should be completed.

The conclusions and recommendations presented in this report are based upon the information

provided to us regarding the proposed project, review of readily available published maps and

reports, review of unpublished consultant’s reports, subsurface conditions encountered in the

exploratory trenches, and professional judgment. This study has been conducted in accordance

with professional geologic and engineering geologic standards current at the time this study was

performed and in the geographic area of the study site; no other warranty is expressed or implied.

Site conditions described in the text are those existing at the time of our field exploration, and are

not necessarily representative of such conditions at other locations and times. In the event that

changes in nature, design or location of the proposed project are planned, or if it is found during

construction that subsurface conditions differ from those described herein, then the conclusions

and recommendations in this report shall be considered invalid, unless the changes are reviewed,

and the conclusions and recommendations are modified or approved in writing.

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We trust this report provides the necessary information you need for your due diligence

evaluation of the site. If you have any questions, please contact the undersigned at (925) 484-

0220. Thank you for the opportunity of providing our professional services.

Respectfully submitted,


Michael Clark

Consulting Principal Geologist

CEG 1264

Gregory J. Ruf

Principal Engineer

GE 2940

Frank Berlogar

Principal Engineer

RCE 20383

MC/GJR/FB:aw

Attachments:

References

Tables – Topographic Maps and Aerial Photographs

Plate 1 – Vicinity Map

Plate 2 – Engeo Site Plan

Plate 3 – Site Plan

Plate 4 –Regional Geologic Map

Plate 5 – Vicinity Geologic Map

Plate 6 – Fault Activity Map

Plate 7 – Earthquake Fault Hazard Zone Map

Plate 8 – Logs of Trenches T-1 through T-6

U:\@@@Public\1-Pleasanton\3823 Grupe - Ersted Hayward\100\Supp Fault Study - 29118.docx

January 6, 2017



REFERENCES

California Division Of Mines And Geology, January 19, 1981, Fault Evaluation Report Fer-103

California Geological Survey, 1982, California Earthquake Fault Hazard Zone, Earthquake Fault

Zones Map, Hayward-7.5' Quadrangle.

California Geological Survey, California Department of Conservation, Division of Mines

and Geology (2000), Digital Images of Official Maps of Alquist-Priolo Earthquake

Fault Zones of California, Central Coast Region.

Chin, J.L., Morrow, J.R., Ross, C.R., and Clifton, H.E. (1993), Geologic Maps of Upper

Cenozoic deposits in Central California, U.S.G.S., Miscellaneous Investigation Series Map I-

1943.

Crane, R. C., 1988, NCGS Field Trip Guide to the Geology of the San Ramon Valley and

Environs.

Dibblee, T.W., Jr., 1980, Preliminary Geologic Map of the Hayward Quadrangle, Alameda

County, California, U.S. Geological Survey Open-File Report.

Ellen, D.S. and Wentworth, C.M. (1995), Hillside Materials and Slopes of the San Francisco Bay

Region, California: U.S. Geological Survey Professional Paper 1357.

ENGEO Incorporated, July 26, 2005, Fault Exploration, Ersted et al Property, Hayward,

California, Project No. 6799.1.001.01.

ENGEO Incorporated, July 13, 2007, Supplemental Fault Exploration, Ersted et al Property,

Hayward, California, Project No. 6799.1.002.01.

Graymer, R.W., 1995, Geologic Map of the Hayward Fault Zone, U.S. Geological Survey, Open-

File Report 95-597.

Hart, E.W. and Bryant, William A., revised 1997 (Supplements 1 and 2 added 1999), Fault-

Rupture Hazard Zones in California, California Department of Conservation, Division of

Mines and Geology, Special Publication 42.

Helley, E. J. and Graymer, R. W. (1997), Quaternary Geology of Contra Costa County and

Surrounding Areas: United States Geological Survey Digital Database Open-File 97-98.

Herd, Darrell, 1978, Map of Quaternary faulting along the northern Hayward fault zone: U.S.

Geological Survey, Open-File Report OF-78-308, scale 1:24,000.;

Hull, Judd, and Associates, and Rose, R.B., 1975c, soil and geologic investigation for proposed

44-unit apartment development at 29298 Mission Boulevard, Unpublished consulting report

filed with the City of Hayward (AP# 200).

Jennings, C. W., 1994, Fault Activity Map of California and Adjacent Areas, California Division

of Mines and Geology, California Geologic Data Map series, Map No. 6.

Lienkaemper, J.J., 1992, Map of recently active traces of the Hayward fault, Alameda and Contra

Costa Counties, California: U.S. Geological Survey, Miscellaneous Field Studies Map MF-

2196, scale 1:24,000.

Liekaemper, J.J., 2006, Digital database of recently active traces of the Hayward fault,

California: U.S. Geological Survey, Data Series DS-177, scale 1:12,000.

January 6, 2017



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 Investigations Series Map I-813, scale 1:24,000.

Schlocker, J. (1970), Generalized Geologic Map of the San Francisco Bay Region, California:

United States Geological Survey Open-File Report 71-246, scale 1:500000.

Scholz, Ando, Shaw, 2009, The Mechanics of First Order Splay Faulting: The Strike Slip Case,

Journal of Structural Geology, 32 118-126

USGS, 1980, Hayward Quadrangle, 7½-minute topographic map

Wagner, D.L., Bortugno, E. J. and Mc Junkin, R. D. (1991), Geologic Map of the San Francisco-

San Jose Quadrangle: California Division of Mines and Geology Regional Geologic Map

Series 5A, scale 1:250,000.

January 6, 2017



TABLES

Topographic Maps

Year Scale

(Minutes)

1899 15

1915 15

1947 7.5

1950 7.5

1968 7.5

Aerial Photographs

Year Source

10/14/1974 Pacific Aerial

07/08/1993 US Geological Survey

07/27/2002 Digital Global

12/21/2004 Digital Global

06/11/2005 USDA Farm Service

08/31/2009 US Geological Survey

05/19/2012 Google Earth

10/30/2015 Google Earth

JO

B N

UM

BE

R: 3823.100 D

AT

E: 1-4-17 B

Y: C

C

BASE: PORTION OF U.S.G.S. 7.5 MINUTE TOPOGRAPHIC QUADRANGLE,

HAYWARD, CALIFORNIA

PLATE 1

SITE

0 2000

1"=2000'

VICINITY MAP

ERSTED PROPERTY

HAYWARD, CALIFORNIA

FOR

THE GRUPE COMPANY

JO

B N

UM

BE

R: 3

82

3.10

0 D

AT

E: 1

-5

-1

7 D

RA

WN

B

Y: C

C

PLATE 2

ENGEO

SITE PLAN

ERSTED PROPERTY

MISSION BOULEVARD SOUTH

OF TENNYSON

HAYWARD, CALIFORNIA

FOR

THE GRUPE COMPANY

Berlogar Stevens & Associates

SOIL ENGINEERS * ENGINEERING GEOLOGISTS

FAULT "A"

FAULT "B"

FAULT "C"

FAULT "D"

SUSPECTED

FAULT "E"

??

??

?

?

?

?

T

-

4

B

T

-

4

T

-

9

T

-3

T

-

1

3

T

-

1

4

T

-

1

5

T

-

1

6

T

-2B

T

-2

B

T

-2

A

T

-2

C

T

-

1

0

T

-

5T

-

5

A

T

-

1

T

-

3

T

-

2

T

-

4

?

?

?

?

?

?

?

?

?

?

?

?

?

?

?

?

?

?

?

?

F

A

U

L

T

1

F

A

U

L

T

2

E

T

-

1

ET

-2

E

T

-

3

37

TR

7

T

R

8

T

3

(1

9

7

5

)

T

1

(

2

0

1

2

)

T

4

(

1

9

7

5

)

L

2

(

2

0

1

2

)

T

1

(

1

9

7

5

)

T

-

1

T

-

5

T

-

4

T

-

2

T-3

HAYWARD FAULT

ZONE

62

32

29

21

29

21

36

66

40

SITE PLAN

ERSTED PROPERTY

MISSION BOULEVARD SOUTH

OF TENNYSON

HAYWARD, CALIFORNIA

FOR

THE GRUPE COMPANY



EXPLANATION

PROPERTY LINE

DEVELOPMENT AREA

TRENCH LOCATION (THIS STUDY)

APPROXIMATE TRENCH LOCATION

(C&A 2012)


(ENGEO, 2005)


(BERLOGAR GEOTECHNICAL CONSULTANTS, 2001)


(EARTH SYSTEMS CONSULTANTS, 1980)


(JUDD HULL & ASSOCIATES, 1975)


(SOIL ENGINEERING CONSULTANTS, 1973)

SOUTHWESTERN LIMIT OF EARTHQUAKE FAULT

HAZARD ZONE (STATE OF CALIFORNIA, 1982)

APPROXIMATE THRUST FAULT LOCATION

(ENGEO, 2005)

APPROXIMATE THRUST FAULT LOCATION

(CRANE, 1988)

APPROXIMATE FAULT LOCATION

(BERLOGAR STEVENS & ASSOCIATES (THIS STUDY)


(BERLOGAR GEOTECHNICAL CONSULTANTS, 2001)



STRIKE AND DIP OF SHEAR (ENGEO, 2005)

STRIKE AND DIP OF SHEAR


APPROXIMATE LOCATION OF PHOTO LINEAMENT

(ENGEO, 2005)

JO

B N

UM

BE

R: 3

82

3.10

0 D

AT

E: 1

-4

-1

7 D

RA

WN

B

Y: C

C

PLATE 3

0 100

1"=100'

WORKING DRAWING

IN PROGRESS

ET-3

T-16

T-4

T4 (1975)

TR8

L2 (2012)

JO

B N

UM

BE

R: 3823.100 D

AT

E: 1-4-17 B

Y: C

C

BASE: CGS, 2002, GEOLOGIC MAP OF CALIFORNIA

PLATE 4

0 20 MILES

1"=20 MILES

SITE

REGIONAL GEOLOGIC MAP

ERSTED PROPERTY

HAYWARD, CALIFORNIA

FOR

THE GRUPE COMPANY

JO

B N

UM

BE

R: 3823.100 D

AT

E: 1-4-17 B

Y: C

C

BASE: GEOLOGIC MAP OF THE HAYWARD FAULT ZONE, CONTRA COSTA,

ALAMEDA, AND SANTA CLARA COUNTIES, CALIFORNIA: A DIGITAL DATABASE BY:

R.W. GRAYMER, D.L. JONES, AND E.E. BRABB

PLATE 5

0 4000

1"=4000'

EXPLANATION OF SYMBOLS

UNDIVIDED QUATERNARY DEPOSITS

MELANGE

KNOXVILLE CONGLOMERATE BEDS

KERATOPHYRE

VICINITY GEOLOGIC MAP

ERSTED PROPERTY

HAYWARD, CALIFORNIA

FOR

THE GRUPE COMPANY

SITE

Jsv

Qu

JKfm

JKkc

Jsv

JO

B N

UM

BE

R: 3823.100 D

AT

E: 1-4-17 B

Y: C

C

BASE: CGS, 2010, FAULT ACTIVITY MAP

PLATE 6

0 5 MILES

1"=5 MILES

SITE

FAULT ACTIVITY MAP

ERSTED PROPERTY

HAYWARD, CALIFORNIA

FOR

THE GRUPE COMPANY

JO

B N

UM

BE

R: 3823.100 D

AT

E: 1-4-17 B

Y: C

C

PLATE 7

0 2000

1"=2000'

BASE: PORTION OF CGS, 2012, EARTHQUAKE ZONES OF REQUIRED INVESTIGATION,

HAYWARD QUADRANGLE

EARTHQUAKE FAULT HAZARD ZONE MAP

ERSTED PROPERTY HAYWARD, CALIFORNIA FOR

THE GRUPE COMPANY

SITE

A

A

G

F

D

D

D

C

B

E

E

C

WEST END

0+00 0+10 0+20 0+30 0+40

0+50 0+60 0+70 0+80 0+90

EAST END

SOUTHEAST END

0+00 0+10 0+20 0+30 0+40 0+50 0+60

0+70 0+80 0+90 1+00 1+10

1+20 1+30 0+40 1+50

1+60 1+70 1+80 1+90 2+00

A

?

?

?

A

A

A

T

U

V

PS

R

R

Q

M

P

M

J

O

N

F

L

J

K

J

H

G

I

H

G

F

F

B

F

D

B

B

D

F

C

CHLORITE COBBLE

WITH WEATHERING

RIND APPROXIMATELY

2 INCHES THICK

IMBRICATED

STRETCHED

CALCIUM

CARBONATE STRINGERS

N80°W 48°N

MIXED AND CONVOLUTED

FOLDING OF WHITE

AND BROWN TO BLACK CLAY

FAULT

N60°W52°N WHITE TO

LIGHT GRAY CLAY

GOUGE CALCIUM

CARBONATE RICH AT

BOTTOM OF TRENCH

GOUGE

STRIKE 42°W

FINE-GRAINED

SANDSTONE, RED

N52°W60°N

FRAGMENTS OF

SCHIST, SHALE AND

QUARTZ

CALCIUM

CARBONATE

ANGULAR ROCK

VOLCANIC?

MA

TC

H LIN

E

2+00 2+10

2+20 2+30 2+40 2+50 2+60 2+70 2+80

2+90 3+00 3+10 3+20 3+30 3+40 3+50

3+60 3+70 3+80 3+90

NORTHEAST END

A

A

A

X

C

X

X

W

L

W

T

T

V

SHALE

SAND LENS

FILL

FILL

FILL

FILL

FILL

Y

Y

MA

TC

H LIN

E

?

A

A

A

A

B

G

F

B

B

B

B

C

D

E

E

D

E

F

D

F

FAULT

HARD CALCIUM

CARBONATE

CONCRETION

CALCIUM CARBONATE

SHEAR N60W 55N

BASALT, HIGHLY

STRETCHED,

COMPLETELY

WEATHERED

SHEAR N40W 47N

CALCIUM CARBONATE SEAM

SHEAR N75W 50N

VOLCANIC INCLUSIONS, COMPLETELY

WEATHERED, CALCIUM CARBONATE RICH

CALCIUM

CARBONATE

GOUGE

N65W 60N AT

BOTTOM OF

TRENCH

SOUTH END

0+00 0+10 0+20 0+30 0+40 0+50 0+60 0+70 0+80 0+90 1+00 1+10 1+20 1+30 1+40 1+50

NORTH END

D

A

A

A

A

E

D

C

C

B

C

D

D

D

SOUTH END

0+00 0+10 0+20 0+30

0+40 0+50 0+60 0+70 0+80 0+90

1+00 1+10 1+20 1+30 1+40 1+50

NORTH END

CALCIUM CARBONATE

VEIN ALONG CONTACT

C

A

B

C

D

FAULT

N73W 90 AT BOTTOM

OF TRENCH

SOUTHWEST END

0+00 0+10 0+20 0+30

NORTHEAST END

A

B

C

D

D

B

SILTSTONE COBBLES

FAULT

N52W 80N AT BOTTOM OF TRENCH

SOUTHWEST END

0+00 0+10 0+20 0+30

NORTHEAST END

TRENCH LOGS

TRENCH T-1 THROUGH T-6

ERSTED PROPERTY

HAYWARD, CALIFORNIA

FOR

THE GRUPE COMPANY



JO

B N

UM

BE

R: 3

823

.1

00

D

AT

E: 1

-4

-1

7 D

RA

WN

B

Y: C

C

PLATE 8

0 5

1"=5'

TRENCH T-1

LOG OF NORTH WALL

TREND N62°E

TRENCH T-1

LOG OF NORTH WALL (CONTINUED)

TREND N62°E

130

EL

EV

AT

IO

N IN

F

EE

T

135

140

145

125

GROUND SURFACE AND BOTTOM OF TRENCH

GEOLOGIC CONTACT, SOLID WHERE SHARP, DASHED WHERE APPROXIMATE

CLAY, DARK GRAY TO BLACK, WET, SOFT TO MEDIUM STIFF

CLAY, BLACK, DRY, VERY STIFF TO HARD, CONTAINS CALCIUM CARBONATE

NODULES ( UP TO 1 INCH DIAMETER) AND STRINGERS (UP TO 3 INCH DIAMETER)

BRECCIA, LIGHT GRAY-BROWN, DRY, CONTAINS ANGULAR ROCK CLASTS FROM

APPROXIMATELY 1/2 TO 6 INCH DIAMETER, SERPENTINIZED ROCK, HIGHLY

WEATHERED

CLAYSTONE, DARK BROWN, SLIGHTLY MOIST, STIFF TO VERY STIFF,

COMPLETELY WEATHERED

CLAYSTONE, DARK ORANGE-BROWN, SLIGHTLY MOIST, STIFF, COMPLETELY

WEATHERED

BRECCIA, MEDIUM ORANGE-BROWN, SLIGHTLY MOIST, STIFF, COMPLETELY

WEATHERED

BRECCIA, MEDIUM BROWN, SLIGHTLY MOIST, STIFF MATRIX, COMPLETELY

WEATHERED

CLAYSTONE, STREAKS OF BLUE, GRAY, BLACK AND LIGHT GRAY, SLIGHTLY

MOIST, STIFF, COMPLETELY WEATHERED

CLAY, MEDIUM RED-BROWN, SLIGHTLY MOIST, STIFF TO VERY STIFF

CLAY, LIGHT TAN TO WHITE, CALCIUM CARBONATE RICH

CLAY, MOTTLED BROWN AND BLUE, SLIGHTLY MOIST, VERY STIFF

SHALE, SHATTERED, DARK BROWN, HIGHLY WEATHERED, NO APPARENT

BEDDING

CLAY, VERY LIGHT BLUE, SLIGHTLY MOIST, VERY STIFF

BRECCIA, CLAST SUPPORTED, GRAVEL TO COBBLES

CLAY WITH ANGULAR GRAVEL SIZE ROCK FRAGMENTS, DARK BROWN, STIFF TO

HARD

CLAY WITH ROUNDED GRAVEL SIZE ROCK FRAGMENTS, LIGHT TAN TO LIGHT

GRAY, WITH STREAKS OF UNIT "A" IN UPPER PART

BRECCIA, DARK GREENISH GRAY, CLAST SUPPORTED

BRECCIA, LIGHT GRAY, HIGH CALCIUM CARBONATE CONTENT

SHALE, SHATTERED, VERY DARK BROWN, NO STRUCTURE, FRACTURES

APPROXIMATELY 1 TO 3 INCHES

SHALE/SLATE, LIGHT GRAY, STRONG TO VERY STRONG, MODERATELY

WEATHERED

CLAY, BLACK, HARD, CONCODIAL FRACTURES, CONTAINS SLATE, SCHIST AND

QUARTZ ROCK

SCHIST, SHATTERED

CLAY, LIGHT BLUE WITH ORANGE BROWN DECOMPOSED ROCKS, SLIGHTLY

MOIST, VERY STIFF

CLAYEY SHALE (GRAVEL SIZE ANGULAR FRAGMENTS OF SHALE) DARK BROWN

WITH WHITE CALCIUM CARBONATE STRINGERS

CLAY WITH SCATTERED ANGULAR ROCK FRAGMENTS, MEDIUM BROWN WITH

ABUNDANT CALCIUM CARBONATE STRINGERS AND NODULES

SANDY GRAVELLY CLAY WITH WOOD FRAGMENTS AND ROTTED GRASS,

MOTTLED BROWN AND BLACK, SLIGHTLY MOIST, SOFT

T-1 EXPLANATION

A

B

C

E

D

F

G

H

I

J

K

TRENCH T-2

LOG OF NORTH WALL

TREND N68°E

TRENCH T-3

LOG OF WEST WALL

TREND N4°E

TRENCH T-6

LOG OF WEST WALL

TREND N-S

TRENCH T-4

LOG OF NORTH WALL

TREND N35°E

TRENCH T-5

LOG OF NORTH WALL

TREND N47°E

110

EL

EV

AT

IO

N IN

F

EE

T

115

120

125

105

L

M

N

O

P

Q

R

S

T

U

V

W

X

Y

FILL



SANDY GRAVELLY CLAY, DARK GRAY, WET AT SURFACE, SLIGHTLY MOIST AT

BASE, SOFT

GRAVELLY SANDY CLAY TO CLAYEY SAND, DARK GRAY, SLIGHTLY MOIST,

MEDIUM STIFF TO STIFF

SILTY GRAVELLY CLAY, BLACK WITH ABUNDANT WHITE CALCIUM CARBONATE

NODULES UP TO APPROXIMATELY 1 INCH DIAMETER, HARD

SILTY GRAVELLY CLAY, LIGHT BROWN, DRY, HARD, GRAVEL IS BLACK ROCK

FRAGMENTS

SANDY GRAVEL, LIGHT BROWN, DRY, LOOSE TO DENSE, CLAST SUPPORTED,

GRAVEL IS ROUNDED UP TO 2 INCH DIAMETER

SANDSTONE AND SILTSTONE COBBLES AND BOULDERS IN CLAY MATRIX

(CONGLOMERATE), DARK GRAY WHERE WEATHERED

SILTSTONE, LIGHT BROWN NO APPARENT BEDDING, JOINTS AT ABOUT 1/2 INCH

N60W>8N

T-2 EXPLANATION

A

B

C

E

D

F

G



SILTY CLAY, BLACK, DRY, SOFT TO STIFF

CLAY, BLACK WITH OCCASIONAL CALCIUM CARBONATE NODULES

APPROXIMATELY 1/2 INCH DIAMETER

CLAY, BLACK WITH COMMON TO ABUNDANT WHITE CALCIUM CARBONATE

STRINGERS IMBRICATED TO UPPER AND LOWER CONTACTS

CLAY, LIGHT TAN TO LIGHT BROWN, DRY, HARD, WITH ABUNDANT CALCIUM

CARBONATE VEINS

CLAY, MEDIUM BROWN, DRY, HARD

T-3 EXPLANATION

A

B

C

D



SILTY CLAY, BLACK, MOIST TO SLIGHTLY MOIST, SOFT TO STIFF

CLAY, BLACK WITH ABUNDANT CALCIUM CARBONATE NODULES AND

STRINGERS, DRY TO SLIGHTLY MOIST, HARD

CLAY, MEDIUM BROWN, SLIGHTLY MOIST TO DRY, HARD, CONTAINS SOME

CALCIUM CARBONATE IN-FILL VEINS

CLAY, LIGHT BROWN TO LIGHT TAN, SLIGHT GREEN TINT, DRY, HARD

T-4 EXPLANATION

A

B

C

D



SILTY CLAY, BLACK, MOIST TO SLIGHTLY MOIST, SOFT TO STIFF

CLAY, LIGHT TAN, DRY, STIFF TO VERY STIFF

CLAY, MEDIUM GREEN BROWN, DRY, STIFF TO HARD, CONTAINS HIGHLY

WEATHERED SILTSTONE COBBLES

CLAY, LIGHT BROWN TO MEDIUM BROWN WITH GREEN TINT, DRY, HARD

T-5 EXPLANATION

A

B

C

D



SILTY CLAY, BLACK, SLIGHTLY MOIST, STIFF TO VERY STIFF

CLAYSTONE WITH ABUNDANT CALCIUM CARBONATE NEAR BASE OF UNIT, DARK

BROWN TO BLACK WITH WHITE STRINGERS AND LOOSE NODULES

CLAYSTONE WITH SOME CALCIUM CARBONATE NEAR TOP OF UNIT, DRY, DARK

TO LIGHT ORANGE-BROWN, CONTAINS FINE-GRAINED ROCK FRAGMENTS

(VOLCANIC) WITH FEW GRAVEL, SANDSTONE, WELL ROUNDED WITH

WEATHERING RIND

CLAYSTONE, LIGHT GRAY TO WHITE, DRY, VERY STIFF, CALCIUM CARBONATE

RICH

CLAYSTONE, MEDIUM TO DARK BROWN, DRY, VERY STIFF TO HARD, CONTAINS

GRAVEL WELL ROUNDED TO ABOUT 2 INCH DIAMETER OF SERPENTINITE AND

VOLCANIC ROCK

CLAYSTONE, SIMILAR TO UNIT "E" BUT LIGHT YELLOW-BROWN, CONTAINS

GRAVEL OF SERPENTINITE AND VOLCANIC ROCK

CARBONATE ROCK WITH MINOR CLAY CONTENT

T-6 EXPLANATION

A

B

C

E

D

F

G

110

EL

EV

AT

IO

N IN

F

EE

T

115

120

125

105

120

EL

EV

AT

IO

N IN

F

EE

T

125

130

115

110

EL

EV

AT

IO

N IN

F

EE

T

115

120

125

105

130

EL

EV

AT

IO

N IN

F

EE

T

135

140

125

EL

EV

AT

IO

N IN

F

EE

T

115

120

125

EL

EV

AT

IO

N IN

F

EE

T

120

125

130

EL

EV

AT

IO

N IN

F

EE

T

105

110

115

EL

EV

AT

IO

N IN

F

EE

T

110

115

120

115

EL

EV

AT

IO

N IN

F

EE

T

120

125

130

110

125

EL

EV

AT

IO

N IN

F

EE

T

130

135

140

120

130

EL

EV

AT

IO

N IN

F

EE

T

135

140

145

140

EL

EV

AT

IO

N IN

F

EE

T

145

150

155

E

Documents

Appendix D-3 Supplemental Fault Ground Rupture