geologic hazards assessment and · pdf fileto review the construction plans before they go to...

GEOLOGIC HAZARDS ASSESSMENT AND GEOTECHNICAL EVALUATION

SCIENCE TECHNOLOGY PHASE II LAS POSITAS COMMUNITY COLLEGE

LIVERMORE, CALIFORNIA

PREPARED FOR: Chabot-Las Positas Community College District

5020 Franklin Drive Pleasanton, California 94588

PREPARED BY: Ninyo & Moore

Geotechnical and Environmental Sciences Consultants 1956 Webster Street, Suite 400

Oakland, California 94612

June 12, 2009 Project No. 401294018

June 12, 2009 Project No. 401294018

Mr. Jeffrey Kingston Chabot-Las Positas Community College District 5020 Franklin Drive Pleasanton, California 94588

Subject: Geologic Hazards Assessment and Geotechnical Evaluation Science Technology Phase II Las Positas Community College Livermore, California

Dear Mr. Kingston:

Thank you for the opportunity to perform this geologic hazards assessment and geotechnical evaluation for the proposed Science Technology Building Phase II to be located at Las Positas College in Livermore, California. This report presents our geologic hazards assessment and our geotechnical findings, conclusions, and recommendations regarding the proposed project.

As an integral part of our role as the geotechnical engineer-of-record, we request the opportunity to review the construction plans before they go to bid and to provide follow-up construction observation and testing services.

We appreciate the opportunity to be of service on this project.

Sincerely, NINYO & MOORE

Kristi A. Gonzalez Senior Staff Engineer

Mark R. Caruso, P.G., C.E.G. Principal Engineering Geologist

Peter C. Connolly, P.E., G.E. Senior Engineer

KAG/PCC/MRC

Distribution: (6) Addressee

Las Positas Community College June 12, 2009 Livermore, California Project No. 401294018

401294018 R Geo Eval.doc i

TABLE OF CONTENTS Page

1. INTRODUCTION ....................................................................................................................1

2. SCOPE OF SERVICES............................................................................................................1

3. SITE DESCRIPTION...............................................................................................................3

4. PROJECT DESCRIPTION ......................................................................................................4

5. FIELD EXPLORATION AND LABORATORY TESTING...................................................4

6. GEOLOGY AND SUBSURFACE CONDITIONS .................................................................5 6.1. Regional Geologic Setting............................................................................................5 6.2. Site Geology .................................................................................................................5 6.3. Subsurface Conditions ..................................................................................................6

6.3.1. Pavement Section................................................................................................6 6.3.2. Clay Overbank Deposit .......................................................................................6 6.3.3. Alluvium .............................................................................................................6

6.4. Groundwater .................................................................................................................7

7. GEOLOGIC HAZARDS AND GEOTECHNICAL ISSUES ..................................................7 7.1. Seismic Hazards............................................................................................................7

7.1.1. Historical Seismicity ...........................................................................................7 7.1.2. Faulting and Ground Surface Rupture ................................................................9 7.1.3. Strong Ground Motion.......................................................................................11 7.1.4. Liquefaction and Strain Softening ....................................................................13 7.1.5. Dynamic Settlement ..........................................................................................14 7.1.6. Seismic Slope Stability .....................................................................................14 7.1.7. Tsunamis and Seiches .......................................................................................14

7.2. Landsliding .................................................................................................................15 7.3. Flood Hazards.............................................................................................................15 7.4. Expansive Soils...........................................................................................................15 7.5. Unsuitable Materials...................................................................................................16 7.6. Static Settlement .........................................................................................................16 7.7. Corrosive/Deleterious Soils ........................................................................................16 7.8. Excavation Characteristics .........................................................................................17

8. CONCLUSIONS ....................................................................................................................17

9. RECOMMENDATIONS........................................................................................................18 9.1. Earthwork ...................................................................................................................18

9.1.1. Site Preparation .................................................................................................18 9.1.2. Observation and Removals ...............................................................................19 9.1.3. Excavation Stabilization and Temporary Slopes ..............................................20 9.1.4. Construction Dewatering ..................................................................................22 9.1.5. Utility Trenches.................................................................................................22 9.1.6. Material Requirements ......................................................................................23


401294018 R Geo Eval.doc ii

9.1.7. Lime Treatment of Expansive Soils..................................................................24 9.1.8. Subgrade Preparation ........................................................................................25 9.1.9. Fill Placement and Compaction ........................................................................26 9.1.10. Rainy Weather Considerations..........................................................................27

9.2. Foundations.................................................................................................................28 9.2.1. Slab-On-Grade Foundations .............................................................................28 9.2.2. Lateral Resistance of Shallow Foundations ......................................................31 9.2.3. Uplift Anchors...................................................................................................31

9.3. Seismic Design Considerations ..................................................................................31 9.4. Preliminary Pavement Design ....................................................................................32 9.5. Concrete......................................................................................................................33 9.6. Moisture Vapor Retarder ............................................................................................34 9.7. Drainage and Site Maintenance..................................................................................35 9.8. Review of Construction Plans ....................................................................................35 9.9. Pre-Construction Conference .....................................................................................35 9.10. Construction Observation and Testing .......................................................................36

10. LIMITATIONS.......................................................................................................................37

11. REFERENCES .......................................................................................................................39


401294018 R Geo Eval.doc iii

Tables Table 1 – Historic Earthquakes ........................................................................................................8 Table 2 – Principal Active Faults ...................................................................................................10 Table 3 – Criteria for Deleterious Soils on Concrete.....................................................................17 Table 4 – Recommended OSHA Material Classifications and Allowable Slopes .........................21 Table 5 – Recommended Material Requirements ..........................................................................24 Table 6 – Subgrade Preparation Recommendations ......................................................................25 Table 7 – Recommended Compaction Requirements ....................................................................27 Table 8 – Recommended Bearing Design Parameters for Footings ..............................................29 Table 9 – Modulus of Subgrade Reaction for Footings .................................................................30 Table 10 – Recommended Lateral Design Parameters for Shallow Foundations..........................31 Table 11 – 2007 California Building Code Seismic Design Criteria.............................................32

Figures Figure 1 – Site Location Map Figure 2 – Site Plan and Boring Location Map Figure 3 – Regional Geologic Map Figure 4 – Cross Section A-A’ Figure 5 – Fault Location Map Figure 6 – Site-Specific Acceleration Response Spectra Figure 7 – Seismic Hazard Map

Appendices Appendix A – Boring Logs Appendix B – Laboratory Testing Appendix C – Typical Earthwork Guidelines


401294018 R Geo Eval.doc 1

1. INTRODUCTION

In accordance with your request, we have performed a geologic hazards assessment and geotechni-

cal evaluation for the proposed Science Technology Phase II at Las Positas College located in

Livermore, California (Figure 1). The purpose of our study was to evaluate the potential geologic

hazards and geotechnical conditions at the subject site, and present our recommendations for the

design and construction of this project. Our evaluation was conducted in conformance with the

guidelines contained in California Geological Survey – Note 48, Checklist for the Review of Engi-

neering Geology and Seismology Reports for California Public Schools, Hospitals, and Essential

Services Buildings, used by the California Geological Survey (CGS) in their evaluation of geologic

hazard reports for conformance with the requirements of the California Division of the State Archi-

tect (DSA) Interpretation of Regulations Document IR A-4, revised November 1, 2007. The latest

version of CGS’s Note 48 is dated October, 2007. Our evaluation is also in conformance with

Chapter 18A of Title 24, Part 2, Volume 2 of the 2007 California Building Code (CBC).

2. SCOPE OF SERVICES

Ninyo & Moore’s scope of services for this phase of the project generally included review of our

previous studies performed on the Las Positas College campus, review of pertinent geologic and

geotechnical background data, performance of a geologic reconnaissance, subsurface evaluation,

laboratory testing, and engineering analysis with regard to the proposed construction. Specifi-

cally, we performed the following tasks:

• Review of background data listed in the References section of this report. The data reviewed included geotechnical reports by Ninyo & Moore, topographic maps, geologic data, stereo-scopic aerial photographs, fault maps, landslide hazard maps, flood hazard maps, and a preliminary site plan (Kwan Henmi Architecture/Planning, 2009) for the project, in addition to as-constructed plans of Building 1800.

• Prepared a geotechnical design memorandum that provided preliminary recommendations to assist the structural engineer with project design.

• Performed a preliminary site reconnaissance to observe the surficial geotechnical conditions and to mark the proposed boring locations for utility marking services.



• Coordinated with Underground Service Alert (USA) and Las Positas College facilities person-nel to locate the underground utilities in the vicinity of the proposed borings.

• Obtained a geotechnical exploration boring permit from Zone 7 Water Agency.

• Performed a subsurface evaluation consisting of drilling, logging, and sampling of three small-diameters, hollow-stem auger borings. A representative of Ninyo & Moore logged the subsurface conditions exposed in the borings, and collected bulk and relatively undisturbed samples for laboratory testing.

• Backfilled the exploratory borings in accordance with the requirements of the Zone 7 Water Agency, and patched the ground surface with appropriated materials where needed.

• Disposed of soil cuttings from the exploratory borings at a designated onsite location.

• Performed laboratory testing on soil samples recovered during the subsurface study to evalu-ate Atterberg limits, dry density, water content, unconfined compressive strength, and soil corrosivity.

• Compiled and analyzed the available subsurface data and the findings from our geologic background review to evaluate the possible geologic and seismic hazards present onsite; including landsliding, faulting, liquefaction, dynamic settlement, etc. for the proposed Science Technology Phase II Building.

• Compiled and analyzed the field and laboratory data and the results of our geologic hazard assessment to evaluate and prepare recommendations for the following:

Geotechnical issues that may impact the design, construction, and/or performance of the proposed improvements.

Subsurface conditions anticipated at the site including stratigraphy and depth to groundwater.

Suitability of the site for the proposed construction from a geotechnical standpoint in light of any potential seismic and geologic hazards.

Susceptibility for liquefaction and dynamic settlement.

Site-specific ground motion hazard analysis with design response spectrum in accor-dance with the 2007 California Building Code, and ASCE 7-05 Section 21.2.

Recommendations for placement of engineered fill and specifications for fill materials.

Suitability of lime treatment for the onsite soils would be presented.



Bearing pressures and lateral resistance for shallow foundations.

Pedestrian pavement designs for asphalt concrete and rigid concrete sections.

Recommendations for utility trench backfill, including imported pipe bedding and shad-ing materials, and engineered backfilling using the onsite soils.

Recommendations for perimeter site surface drainage would be provided.

• Preparation of this report presenting the findings and conclusions from our geologic hazards assessment, and our geotechnical recommendations for the design and construction of the proposed improvements.

3. SITE DESCRIPTION

The Las Positas College campus is located east of the San Francisco Bay in the Livermore Valley

which transects the northwest-trending Diablo Range in an east-west direction at approximately

37.7111 degrees north latitude, and -121.8011 degrees west longitude. The college property is an

irregularly-shaped parcel that encompasses approximately 147 acres of gently sloping land. The

campus is located approximately 3,500 feet north of Highway 580 and northeast of the intersec-

tion of Collier Canyon Road and Stone Peak Drive on a gently inclined southwest-facing slope

(Figure 1). A perimeter road circles the campus, linking the parking lots located around the cam-

pus buildings. There is a southwest-trending ephemeral creek immediately northwest of the Las

Positas college property. At the southwest corner of the campus, this ephemeral stream converges

with the south-trending Collier Creek.

The area proposed for the new Science Technology Phase II Building will be detached and

located to the north of the current Science Center Phase I (Building 1800), as shown on Figure 2.

The proposed building will be constructed on a currently undeveloped open lawn area that is

bound by concrete walkways to the east and west, and by Parking Lot G to the north. Grading

activities have taken place throughout this area in the past.



4. PROJECT DESCRIPTION

Based on the Site Plan and associated information prepared by Kwan Henmi Architec-

ture/Planning and Leidenfrost/Horowitz & Associates, respectfully, we understand that the

proposed Science Technology Phase II building addition will have a footprint area of approxi-

mately 12,000 square feet, and will be a steel-framed, two-story structure without a basement. A

new detached greenhouse structure and restrooms will be constructed as part of the proposed im-

provements. We anticipate that the Science Technology Phase II structure will be supported on a

shallow foundation system bearing near the existing grade. At the present time, we are unaware

of the proposed grading plan and assume that minor grading will be needed to develop the site.

5. FIELD EXPLORATION AND LABORATORY TESTING

Our field exploration included a geologic reconnaissance and subsurface exploration conducted

on May 21, 2009. The subsurface exploration consisted of drilling, logging, and sampling of

three (3) small-diameter exploratory borings. The boring locations, as shown on Figure 2, were

selected based on the locations of the proposed improvements; however, due to constraints

associated with the existing site including a material staging area from adjacent construction sites

and maintenance personal requests, Boring B-2 and Boring B-3 were positioned well inside the

proposed building perimeter. Prior to commencing the subsurface exploration, we contacted

Underground Service Alert (USA) to notify utility providers to locate and mark existing utilities on

site. We consulted with facilities personnel to further evaluate the location of existing utilities.

We also obtained a drilling permit from the Zone 7 Water Agency.

The borings were drilled to depths of up to approximately 50½ feet below the existing grade

with a truck-mounted drill rig equipped with hollow-stem auger. A representative of Ninyo &

Moore logged the subsurface conditions exposed in the borings and collected drive and bulk soil

samples. The samples were subsequently transported to our geotechnical laboratory for testing.

Descriptions of the subsurface materials encountered in the borings are presented in the follow-

ing sections; and detailed logs of the borings are presented in Appendix A.



Laboratory testing of soil samples was performed to evaluate in-situ moisture content, dry den-

sity, Atterberg limits, unconfined compressive strength, and soil corrosivity. The results of the in-

situ moisture content and dry density tests are shown at the corresponding sample depths on the

boring logs in Appendix A. The results of the other laboratory tests performed are presented in

Appendix B.

6. GEOLOGY AND SUBSURFACE CONDITIONS

Our findings regarding regional and site geology, subsurface soils, and groundwater conditions at

the subject site are provided in the following sections.

6.1. Regional Geologic Setting

The site is located on the east side of San Francisco Bay in the Coast Ranges geomorphic

province of California. The Coast Ranges are comprised of several mountain ranges and

structural valleys formed by tectonic processes commonly found around the Circum-Pacific

belt. Basement rocks have been sheared, faulted, metamorphosed, and uplifted, and are

separated by thick blankets of Cretaceous and Cenozoic sediments that fill structural valleys

and line continental margins. The San Francisco Bay area has several ranges that trend

northwest, parallel to major strike-slip faults such as the San Andreas, Hayward, and

Calaveras. Major tectonic activity associated with these and other faults within this regional

tectonic framework consists primarily of right-lateral, strike-slip movement. Further discussion

of faulting relative to the site is provided in Section 7.1.2 of this report.

6.2. Site Geology

The Science Technology Phase II project site is mapped as being underlain by Livermore

Gravel by Graymer et al. (1996), Majmunder (1991), Dibblee (2006), and Herd (1977).

Crane (1995) maps the formation as Pleistocene gravels. These maps each indicate a contact

with Quaternary alluvium to the southwest, down the gentle, southwest facing slope. Ellen

and Wentworth (1995), however, map the site as being underlain by the Tertiary Orinda



formation. The findings of our subsurface evaluation (described below), indicate that the

subject site is underlain by Quaternary alluvium, which is probably underlain by Livermore

Gravel. A Regional Geologic Map prepared by Graymer et al (1996) is provided as Figure 3.

6.3. Subsurface Conditions

Materials encountered during our subsurface evaluation included lawn, a flexible pavement

section, and a clay overbank deposit underlain by older alluvium. Generalized descriptions

of the units encountered are provided in subsequent sections. More detailed descriptions are

presented on the boring logs in Appendix A. A cross section depicting our interpretation of

the site geology is provided on Figure 4.

6.3.1. Pavement Section

Borings B-1 and B-2 were located in Parking Lot G. The pavement sections encountered

in these borings consisted of asphalt concrete about 6 inches thick over an aggregate

base section about 12 inches thick.

6.3.2. Clay Overbank Deposit

A clay overbank alluvial deposit was encountered in Boring B-3 from below the lawn to

a depth about 1½ feet. The same unit is present elsewhere on the campus; but is rela-

tively thin here as found in Boring B-3, and is absent below the pavement section in

Borings B-1 and B-2, due to prior grading activities on site. As encountered, this unit is

generally moderate to highly expansive consisting of dark brown, dry to damp, stiff,

clay with trace sand and few gravel with scattered organics. In general, the surficial ma-

terial within the existing lawn area is comprised of this material.

6.3.3. Alluvium

Alluvium was encountered below the clay overbank deposit and pavement section to

the depths explored. As encountered, the alluvium generally consisted of alternating

layers of yellowish brown, light brown, and brown, damp to moist, moderately plastic,



very stiff to hard, clay, and medium dense to very dense, clayey sand. Caliche in the

form of nodules and thin layers was encountered at various depths within the alluvium.

6.4. Groundwater

Groundwater was not encountered in the borings drilled during our subsurface exploration

that extended to depths of up to approximately 50½ feet. However, fluctuations in the

groundwater level may occur due to variations in ground surface topography, subsurface

geologic conditions and structure, rainfall, irrigation, and other factors. The map of historic

high groundwater levels presented within the Seismic Hazard Zone Report for the Liver-

more Quadrangle (CGS, 2008a) indicates that the project site is within an area where

information regarding the depth to historic high groundwater is not available.

7. GEOLOGIC HAZARDS AND GEOTECHNICAL ISSUES

This study considered a number of potential issues relevant to the proposed construction, includ-

ing seismic hazards, expansive soils, unsuitable materials, landsliding and slope stability, flood

hazards, settlement of compressible soil layers from static loading, potential of on-site soils to

corrode ferrous metals and promote sulfate attack on concrete, and excavation characteristics.

These issues are discussed in the following subsections.

7.1. Seismic Hazards

The seismic hazards considered in this study include the potential for ground surface rupture

and ground shaking due to seismic activity, seismically induced liquefaction, dynamic set-

tlement, tsunamis, and seiches. These potential hazards are discussed in the following

subsections.

7.1.1. Historical Seismicity

The site is located in a seismically active region, as is the majority of northern

California. Table 1 summarizes the significant historic earthquakes that have occurred



within a radius of approximately 100 kilometers (62 miles) of the site with a magnitude

of 6.0 or more since 1800.

Table 1 – Historic Earthquakes

Date Magnitude1 (M)

Epicentral Distance1 km (miles)

June 21, 1808 6.0 62 (38.5) June 1838 6.8 54 (33.5) November 26, 1858 6.1 25 (15.5) October 8, 1865 6.3 57 (35.3) October 21, 1868 6.8 26 (16.2) May 19, 1889 6.0 33 (20.5) April 24, 1890 6.0 91 (56.5) April 19, 1892 6.4 78 (48.5) April 21, 1892 6.2 87 (54.0) June 20, 1897 6.2 83 (51.5) March 31, 1898 6.2 75 (46.6) April 18, 1906 7.8 60 (37.3) July 1, 1911 6.6 51 (31.7) April 24, 1984 6.1 44 (27.3) October 18, 1989 7.1 75 (46.6)

Note: 1USGS http://neic.usgs.gov/neis/epic/epic_circ.html

In addition to these significant earthquakes, an earthquake centered along the Greenville

fault, about 15 kilometers northeast of the project site, took place at 11:00 am, Pacific

Standard Time, on January 24, 1980 (United States Geological Survey [USGS], 2008a).

Reported magnitudes for this earthquake include: 5.9 surface wave (USGS, 2008a); 5.9

Richter (Scheimer et al., 1982); 5.8 undefined (USGS, 2008b); and 5.5 Richter

(CDMG, 1980). Associated surface rupture extended approximately 6 kilometers along

the Greenville fault, beginning near the overpass at Interstate 580 and Greenville Road

(USGS, 2008b). The earthquake caused more than $11.5 million in property damage,

with $10 million of this at the Lawrence Livermore Laboratory. A majority of this

damage was non-structural, and included broken windows, broken gas and water lines,

and mobile homes displaced from their foundations. Damage at Lawrence Livermore

Laboratory included broken PVC pipes, paneling, glassware, and overturned

bookshelves (USGS, 2008b; CDMG, 1980).



A small foreshock preceded the earthquake by 1½ minutes, and the earthquake was

followed by a swarm of aftershocks over the next several days. There is conflicting

information regarding the largest of these aftershocks, which occurred on

January 26, 1980 (USGS, 2008a; USGS, 2008b; Scheimer et al., 1982; CDMG, 1980).

Reported magnitudes for this event include: 5.8 Richter (USGS, 2008a); 5.3 Richter

(Scheimer et al., 1982); and 5.2 – 5.8 Richter (CDMG, 1980).

The referenced documents contained no discussion about damage at the Las Positas

College campus resulting from the series of tremors. Our air photo review for the Las

Positas College campus indicates that the campus was in the early stages of develop-

ment at the time of the January 24, 1980, Livermore earthquake, and there is no

evidence to suggest that any structures were damaged during this event.

7.1.2. Faulting and Ground Surface Rupture

The numerous faults in northern California include active, potentially active, and inac-

tive faults. As defined by the CGS, active faults are faults that have ruptured within

Holocene time, or within approximately the last 11,000 years. Potentially active faults

are those that show evidence of movement during Quaternary time (approximately the

last 1.6 million years) but for which evidence of Holocene movement has not been es-

tablished. Inactive faults do not show evidence of movement within Quaternary time.

The site is not located within an Alquist-Priolo Fault Rupture Hazard Zone established

by the state geologist (CDMG, 1982) to delineate regions of potential ground surface

rupture adjacent to active faults. The closest known active fault is the Mount Diablo

Thrust fault located approximately 1.7 miles (2.8 kilometers) northwest of the project

site. Major known active faults in the region consist generally of en-echelon, northwest-

striking, right-lateral, strike-slip faults. These include the Calaveras, Hayward, and San

Andreas faults, located west of the site, and the Greenville fault, located east of the site.

The approximate locations of major faults in the region and their geographic relation-

ship to the project vicinity are shown on Figure 5. Table 2 lists the seismic parameters



for the principal active faults in the project vicinity. The values of fault to site distance,

moment magnitude, and slip rate listed in the table were evaluated using FRISKSP

(Blake, 2001) which is based upon the seismic data published by the USGS and the

CGS (Cao et al., 2003) with consideration for multi-segment events where noted.

Table 2 – Principal Active Faults

Fault Approximate Fault

to Site Distance1 (km/miles)

Moment Magnitude,1 (Mmax)

Slip Rate,1 SR

(mm/year) Fault Type2

Mount Diablo Thrust 2.8/1.7 6.6 2 Reverse Greenville North 7.4/4.8 6.6 2 Strike Slip Calaveras3 12.0/7.2 6.93 11 Strike Slip Hayward4 22.1/13.5 7.26 9 Strike Slip Great Valley 7 23.9/15.1 6.7 1.5 Reverse Concord/Green Valley5 26.9/16.6 6.71 5 Strike Slip Great Valley 5 41.3/25.5 6.5 1.5 Reverse Notes: 1 Blake, 2001 2 Per Cao et. al., 2003 3 Includes Southern, Central, and Northern segments 4 Includes Southern, Northern, and Rodgers Creek segments 5 Includes Concord, Green Valley South, and Green Valley North segments

The closest fault to the project site indicated on published maps (Dibblee, 2006;

Graymer, 1996; Jennings, 1994; Crane, 1995; Majmunder, 1991) is a fault along the

base of the hills about 940 feet northwest of the project site. Jennings (1994) and

Bortugno (1991) refer to this fault as the Livermore fault, and report evidence for

displacement within Quaternary time. Graymer (1996), Crane (1995), and Majmunder

(1991) interpret the fault as a thrust feature wrapping around the base of the hills to the

north, with the hanging wall to the north, while Dibblee (2006) maps the fault as

concealed with the north side of the fault moving up relative to the south side. Detailed

mapping by Dibblee (2006) and Majmunder (1991) indicates that the fault is exposed in

the Pliocene to Pleistocene Livermore Gravels, but is generally concealed by Holocene

alluvium. Crane (1995) labels the thrust fault as “Leading Edge Blind Thrust Mt. Diablo

Domain.” Based upon the information presented above, the fault located approximately

940 feet northwest of the project site should be considered potentially active. The trace



of this fault, as interpreted by the referenced authors, does not cross the site of the

proposed Science Technology Phase II improvements, and it is the opinion of

Ninyo & Moore that sympathetic movement along the fault resulting from a seismic

event on nearby active faults, such as the Greenville fault or the Mount Diablo thrust

system, will not impact the proposed improvements.

Additionally, Ninyo & Moore previously performed a subsurface fault trenching study

to evaluate if northwest-trending lineaments observed in aerial photographs as project-

ing onto the Las Positas Community College Campus were related to faulting. No

evidence of faulting was found within the approximately 660-foot trench excavation

performed across these lineaments (Ninyo & Moore, 2007a).

Based on our review of the referenced geologic maps, stereoscopic aerial photographs,

and the results of our previous fault trenching study, it is our opinion that the Science

Technology Phase II site is not underlain by known active or potentially active faults

(i.e., faults that exhibit evidence of ground displacement in the last 11,000 years and

1,600,000 years, respectively). Therefore, the potential for ground surface rupture due

to faulting at the site is considered low. However, lurching or cracking of the ground

surface as a result of nearby seismic events is possible.

7.1.3. Strong Ground Motion

The site is within 10 kilometers of the Mount Diablo thrust and the Greenville North

faults which are both considered as active faults by the CGS. In order to provide an

Acceleration Response Spectrum (ARS) to model building response to seismic ground

shaking for design of the proposed structures, we performed a site-specific ground

motion hazard analysis in accordance with Section 1614A.1.2 of the CBC (CBSC,

2007) and Section 21.2 of ASCE Standard 7-05 (ASCE, 2006). A ground motion hazard

analysis incorporates a probabilistic and deterministic hazard analysis to evaluate the

Acceleration Response Spectra for the site.



The probabilistic analysis incorporates uncertainties in time, recurrence intervals, size,

and location (along faults) of hypothetical earthquakes. This method thus accounts for

likelihood (rather than certainty) of occurrence and provides levels of ground accelera-

tion that might be more reasonably hypothesized for a finite exposure period. We

conducted our analysis using the FRISKSP program (Blake, 2001) and the database of

fault locations, rupture areas, and recurrence intervals published by the CGS (Cao et al.,

2003). FRISKSP calculates the probability of experiencing various ground accelerations

within the site over a period of time and the probability of exceeding expected ground

accelerations within the lifetime of the proposed structure from significant earthquakes

within a specific radius of search. For the present case, a search radius of 62 miles

(100 kilometers) was selected. We evaluated a hazard level equivalent to a horizontal

ground motion with a recurrence interval of 2,500 years, or a 2 percent probability of

exceedance in 50 years, also known as the ground motion associated with the Maximum

Considered Earthquake (MCE). The results of our probabilistic ground motion analysis

for 5 percent damping are presented in Figure 6.

We conducted the deterministic seismic hazard analysis to evaluate ground shaking

wherein we computed the 5 percent damped, median ARS for characteristic earthquakes

acting individually on known active faults within the region. In our analysis we used

FRISKSP (Blake, 2001) to evaluate the fault to site distance for the database of fault

locations and magnitude published by the CGS (Cao et al., 2003). We found that the

ARS at the site for an earthquake on the Mount Diablo Thrust fault (approximately

2.8 kilometers from the site) with a magnitude of 6.6 exceeds the ARS at the site due to

seismic events on other regional faults. We modeled the MCE ground motion for a

magnitude 6.6 event on the Mount Diablo Thrust fault by scaling the median spectral

response acceleration from the various relationships by 150 percent. In accordance with

Section 21.2.2 of ASCE 7-05 (ASCE, 2006), we constructed the Deterministic MCE

ARS from the largest scaled median spectral response acceleration at each period



evaluated and the lower limit specified in Section 21.2.2. The Deterministic MCE ARS

from our analysis is presented on Figure 6.

The site-specific MCE and design ARS are presented on Figure 6. In accordance with

Section 21.2.3 of ASCE 7-05 (ASCE, 2006), the site-specific MCE ARS is the lesser of

the Probabilistic and Deterministic MCE ARS at each period evaluated. The site-

specific design ARS is equivalent to two-thirds of the site-specific MCE ARS. The de-

sign ARS for a Type D soil profile computed in accordance with Section 1613A of the

CBC and Section 11.4.5 of ASCE 7-05 is presented in Figure 6 for comparison. The

site-specific design ARS presented in Figure 6 is not less than 80 percent of the design

ARS for a Type D soil profile in accordance with Section 21.3 of ASCE 7-05. The spec-

tral ordinates for the site-specific design ARS are tabulated in Figure 6.

Structures bearing partly on fill and partly on native soil may experience different

ground motions for the portion of the structure bearing on fill when compared to the

portion of the structure bearing on native soil. To mitigate the potential for this ground

motion incoherence, we recommend extending the footings to bear on native soil in

Section 9.2.1. We provide alternative recommendations in Section 9.1.2 to excavate

below portions of the foundation to increase the thickness of fill so that footings bear on

a fill layer of relatively consistent thickness.

7.1.4. Liquefaction and Strain Softening

The strong vibratory motions generated by earthquakes can trigger a rapid loss of shear

strength in saturated, loose, granular soils of low plasticity (liquefaction) or in wet, sen-

sitive, cohesive soils (strain softening). Liquefaction and strain softening can result in a

loss of foundation bearing capacity or lateral spreading of sloping or unconfined

ground. Liquefaction can also generate sand boils leading to subsidence at the ground

surface.



The site is not located within a liquefaction hazard zone on the Map of Seismic Hazard

Zones (Figure 7) prepared by the CGS (CGS, 2008b). Moreover, we did not encounter

saturated, loose, cohesionless, granular soils during our subsurface exploration. The co-

hesion and fines content of the granular material encountered in our subsurface

exploration generally did not conform with the characteristics of liquefiable soils pub-

lished by Bray and Sancio (2006). The cohesive soils encountered were not particularly

wet or sensitive. As such, we do not regard liquefaction, strain softening, or related haz-

ards as design considerations.

7.1.5. Dynamic Settlement

The strong vibratory motion associated with earthquakes can also dynamically compact

loose granular soil leading to surficial settlements. Dynamic settlement is not limited to

the near surface environment and may occur in both dry and saturated sand and silt.

Cohesive soils are not typically susceptible to dynamic settlement.

Based on the generally very stiff to hard consistency and cohesive nature of the on-site ma-

terials, we do not regard dynamic settlement onsite as a design consideration.

7.1.6. Seismic Slope Stability

The site is not located within a hazard zone for earthquake-induced landslides on the

Map of Seismic Hazard Zones (Figure 7) prepared by the CGS (CGS, 2008). As such,

we do not regard seismic stability as a design consideration.

7.1.7. Tsunamis and Seiches

Tsunamis are long wavelength seismic sea waves (long compared to ocean depth) gen-

erated by the sudden movements of the ocean floor during submarine earthquakes,

landslides, or volcanic activity. Seiches are waves generated in a large enclosed body of

water. Based on the inland location of the site and considering that there are no large

enclosed bodies of water nearby, the potential for damage due to tsunamis or seiches is

not significant.



7.2. Landsliding

According to published landslide maps, no landslides underlie the project site (Majmunder,

1991; Nilsen, 1975). We did not observe indications of landslides on slopes within the pro-

ject limits during our site reconnaissance or our review of stereoscopic aerial photographs.

7.3. Flood Hazards

Based on our review of the Flood Hazard Map produced by the ESRI/ Federal Emergency

Management Agency (FEMA) Project Impact Hazard Information and Awareness Site

(ESRI, 2007), the site is not within a mapped flood zone. Based on a review of the Dam

Failure Inundation Areas prepared by the Association of Bay Area Governments (ABAG,

2004), the site is not located within an inundation area following a conjectured catastrophic

dam failure. Our review of FEMA Flood Insurance Rate Maps (FEMA, 1997) found that the

site is located in an area considered to be outside the 500-year floodplain.

7.4. Expansive Soils

Some clay minerals undergo volume changes upon wetting or drying. Unsaturated soils

containing those minerals will shrink/swell with the removal/addition of water. The heaving

pressures associated with this expansion can damage structures and flatwork. Geotechnical

evaluations for other projects on campus (Ninyo & Moore 2007b, 2008a, and 2008b) have

found that the near surface soils generally have a high expansion characteristic. We

anticipate that the differential movement related to the shrink/swell behavior of this

material, if located near the ground surface after grading, will be unacceptable for overlying

slabs, pavement, flatwork, and lightly-loaded shallow footings. We provide

recommendations in Section 9.1.2 to remove this material during site grading and replace it

with imported fill or on-site select borrow with low expansion characteristics to reduce the

potential for differential movement due to expansive soils. The removed material may be

stockpiled and re-used as fill below the zone of influence for pavements, slabs, and footings.

Alternative recommendations are provided in Section 9.1.7 to treat the expansive soil with

lime to reduce the expansion characteristic.



7.5. Unsuitable Materials

Soils containing roots or other organic matter are not suitable as fill or subgrade material be-

low structures, pavements, or engineered fill. Surficial soils containing roots or other

organic matter should be removed as part of the clearing and grubbing operations.

7.6. Static Settlement

The proposed structures to be constructed for the Science Technology Phase II building are

relatively light, and the materials encountered in our subsurface exploration are relatively

stiff. We anticipate that static settlement due to structural loads will be negligible.

Differential settlement may be a concern if portions of a building are constructed over a

thick wedge of fill while other portions of the building are constructed over a thin wedge of

fill or on native soil. The anticipated differential settlement arising from this condition may

be reduced by deepening the footings to bear on native material or by excavating to create a

thicker wedge of fill where the native material is shallow. Recommendations to deepen

footings to bear on native soil below the fill are presented in Section 9.2.1. Alternative

recommendations to excavate below footings to reduce the fill thickness differential are

presented in Section 9.1.2.

7.7. Corrosive/Deleterious Soils

An evaluation of the corrosivity of the on-site materials was conducted to assess the poten-

tial impact to concrete and metals. The corrosion potential was evaluated using the results of

limited laboratory testing on samples obtained during our subsurface study. Laboratory test-

ing to quantify pH, resistivity, chloride, and soluble sulfate contents was performed on a

sample of the alluvium. The results of the corrosivity tests are presented in Appendix B. Cal-

trans defines a corrosive environment as an area within 1,000 feet of brackish water or

where the soil contains more than 500 parts per million of chlorides, sulfates of 0.2 percent

or more, or pH of 5.5 or less (Caltrans, 2003). The site is not located within 1,000 feet of a

brackish body of water. The criteria used to evaluate the deleterious nature of soil on con-



crete are listed in Table 3. Based on these criteria, the sample of material tested does not

meet the definition of a corrosive environment and the sulfate exposure to concrete is negli-

gible. Ferrous metals will still undergo corrosion on site, but special mitigation measures are

not be needed. Recommended corrosion mitigation measures are presented in Section 9.5.

Table 3 – Criteria for Deleterious Soils on Concrete

Sulfate Content Percent by Weight

Sulfate Exposure

0.0 to 0.1 Negligible

0.1 to 0.2 Moderate

0.2 to 2.0 Severe

> 2.0 Very Severe

Reference: American Concrete Institute (ACI) Committee 318 Table 4.3.1 (ACI, 2007)

7.8. Excavation Characteristics

We anticipate that the proposed project will involve excavations of up to 3 feet in depth to

cut a level building pad and an additional depth of 3 to 5 feet for footings, utility trenches, or

removal of unsuitable or expansive materials. The surficial geologic units encountered dur-

ing our subsurface evaluation consisted primarily of stiff to hard clay and medium dense to

very dense clayey sand with layers and nodules of caliche. We anticipate that heavy earth-

moving equipment in good working condition should be able to make the proposed

excavations. Near-vertical cuts in these deposits up to 5 feet in depth should remain stable

for a limited period of time. Sloughing of the sidewall may occur, however, particularly if

the sidewall is disturbed during construction operations or exposed to water. Recommenda-

tions for excavation stabilization are presented in Sections 9.1.3.

8. CONCLUSIONS

Based on our review of the referenced background data, geologic field reconnaissance, subsur-

face evaluation, and laboratory testing, it is our opinion that construction of the proposed



improvements is feasible from a geotechnical standpoint. Geotechnical considerations include the

following:

• The site could experience a relatively large degree of ground shaking during a significant earthquake on a nearby fault.

• Some near-surface soil on-site has a relatively moderate to high expansion characteristic. To reduce the potential for differential movement of the proposed improvements due to shrink/swell behavior, we provide recommendations to remove or exclude these materials from the zone of influence below the proposed improvements. Alternative recommendations for lime treatment to mitigate the expansion potential of on-site soils are also provided.

• Some near-surface soils at the subject site contain organic matter. Recommendations for re-moval of this material are presented in Section 9.1.1.

• Ground motion incoherence may be a concern for structures bearing partly on fill and partly on native soil. Recommendations for deepening footings or overexcavation to mitigate this concern are presented.

9. RECOMMENDATIONS

The following guidelines should be used in the preparation of the construction plans. We rec-

ommend that the geotechnical consultant should review the proposed plans prior to construction.

9.1. Earthwork

The earthwork should be conducted in accordance with the relevant grading ordinances hav-

ing jurisdiction, the guidelines presented in Appendix C, and the following

recommendations. The earthwork guidelines are considered part of the geotechnical report,

but are superseded by recommendations made in this section in case of conflict. The geo-

technical engineer should observe earthwork operations. Evaluations performed by the

geotechnical engineer during the course of operations may result in new recommendations,

which could supersede the recommendations in the earthwork guidelines or this section.

9.1.1. Site Preparation

Prior to performing earthwork operations, the site should be cleared of vegetation,

surface soils containing roots or other organic matter, surface obstructions



(e.g., pavements, aggregate base, etc.), rubble and debris, abandoned utilities, and other

deleterious materials. Existing utilities within the project limits, if any, should be re-

routed or protected from damage by construction activities. Trees or other obstructions

that extend below finish grade, if any, should be removed and the resulting holes filled

with compacted soils. Materials generated from the clearing operations should be

removed from the project site and disposed of at a legal dumpsite. Soils containing roots

or other organic matter may be stockpiled for later use as landscaping fill, as authorized

by the District’s representative.

9.1.2. Observation and Removals

Prior to placement of fill or the erection of forms, the District should request an evalua-

tion of the exposed subgrade by the geotechnical consultant. Materials that are

considered unsuitable shall be excavated under the observation of the geotechnical con-

sultant in accordance with the recommendations in this section, or the field

recommendations of the geotechnical engineer.

Unsuitable materials include, but may not be limited to dry, loose, soft, wet, expansive,

organic, or compressible natural soils; and undocumented or otherwise deleterious fill

materials. Unsuitable materials should be removed from below footings, slabs, and

areas to receive fill to the depth of suitable material as evaluated by the geotechnical

engineer in the field.

Some on-site soils have a high expansion characteristic, particularly the dark brown

clay generally found within the upper portion of the native soil profile. We recommend

that highly expansive soils be removed or excluded from within 3 feet of the finish

subgrade below structures and 2 feet below exterior flatwork to reduce the potential for

differential movement and distress to the proposed improvements due to shrink/swell

behavior. The expansive soil may be re-used as general fill below a depth of 3 feet from

finish grade, provided that the material complies with our recommendations for general



fill in Section 9.1.6. Alternatively, the expansive soil may be treated with lime to reduce

its expansive characteristics in accordance with our recommendations in Section 9.1.7.

To mitigate against potential differential settlement or seismic ground motion

incoherence for structures founded partly on fill and partly on native soil, we provide

recommendations in Section 9.2.1 to deepen footings to bear on native soil.

Alternatively, the thickness of fill below portions of the foundation may be increased by

excavation and recompaction. In general, we recommend that the minimum thickness of

fill below footings should not be less than one-third of the maximum thickness of fill

below footings.

Removals shall extend a distance beyond the perimeter of the slabs and footings

equivalent to the depth of removal below the bearing surface. Removals should extend

3 feet outside the building footprint for 3 feet of removal below slabs. Additional

removal may be needed to provide stable temporary slopes as per Section 9.1.3.

9.1.3. Excavation Stabilization and Temporary Slopes

Excavations, including footing and trench excavations, shall be stabilized in accordance

with the Excavation Rules and Regulations (29 Code of Federal Regulations, Part 1926)

stipulated by the Occupational Safety and Health Administration (OSHA, 1989). Stabi-

lization shall consist of shoring sidewalls or laying slopes back. Table 4 lists the OSHA

material type classifications and corresponding allowable temporary slope layback in-

clinations for soil deposits that may be encountered on site. Alternatively, a shoring

system conforming to the OSHA Excavation Rules and Regulations (29 CFR Part 1926)

may be used to stabilize excavation sidewalls during construction. Shoring system crite-

ria for excavations up to 20 feet in depth are listed in the OSHA Excavation Rules and

Regulations (29 CFR Part 1926). The lateral earth pressures listed in Table 4 may be

used to design or select the shoring system. The recommendations listed in this table are

based upon the limited subsurface data provided by our exploratory borings and excava-

tions and reflect the influence of the environmental conditions that existed at the time of



our exploration. Excavation stability, material classifications, allowable slopes, and

shoring pressures should be re-evaluated and revised, as needed, during construction.

Excavations, shoring systems and the surrounding areas should be evaluated daily by a

competent person for indications of possible instability or collapse.

Table 4 – Recommended OSHA Material Classifications and Allowable Slopes

Formation OSHA Classification

Allowable Temporary Slope1,2,3

Lateral Earth Pressure on Shoring4, (psf)

Fill Type C 1½h:1v (34°) 80⋅D + 72

Alluvium (above groundwater) Type B 1h:1v (45°) 45⋅D + 72

1 Excavation sidewalls in cohesive soils may be benched to meet the allowable slope criteria (meas-ured from the bottom edge of the excavation). The allowable bench height is 4 feet. The bench at the bottom of the excavation may protrude above the allowable slope criteria.

2 In layered soils, no layer shall be sloped steeper than the layer below. 3 Temporary excavations less than 5 feet deep may be made with vertical side slopes and remain un-

shored if judged to be stable by a competent person (29 CFR Part 1926.650). 4 ‘D’ is depth of excavation for excavations up to 20 feet deep. Includes a surface surcharge equiva-

lent to two feet of soil.

The shoring system should be designed or selected by a suitably qualified individual or

specialty subcontractor. The shoring parameters presented in this report is preliminary

design criteria, and the designer should evaluate the adequacy of these parameters and

make appropriate modifications for their design. We recommend that the contractor take

appropriate measures to protect workers. OSHA requirements pertaining to worker

safety should be observed.

We understand that the proposed excavations will be in close proximity to existing

structures. Excavations made in close proximity to existing structures may undermine

the foundation of those structures and/or cause soil movement related distress to the

existing structures. Stabilization techniques for excavations in close proximity to

existing structures will need to account for the additional loads imposed on the shoring

system and appropriate setback distances for temporary slopes. The geotechnical



engineer should be consulted for additional recommendations if the proposed

excavations cross below a plane extending down and away from the foundation bearing

surfaces of the adjacent structure at an angle of 2:1 (horizontal to vertical).

9.1.4. Construction Dewatering

Groundwater was not encountered in our exploratory borings. However, significant

fluctuations in the groundwater level may occur as a result of variations in seasonal pre-

cipitation and other factors. Water intrusion into the excavations may occur as a result

of groundwater intrusion or surface runoff. The contractor should be prepared to take

appropriate dewatering measures in the event that water intrudes into the excavations.

Considerations for construction dewatering should include anticipated drawdown, vol-

ume of pumping, potential for settlement, and groundwater discharge. Disposal of

groundwater should be performed in accordance with the guidelines of the Regional

Water Quality Control Board.

9.1.5. Utility Trenches

Trenches constructed for the installation of underground utilities should be stabilized in

accordance with our recommendations presented in Section 9.1.3. Utility trenches

should be backfilled with materials that conform to our recommendations in

Section 9.1.6. Bedding materials should conform to the specifications of the pipe or

conduit manufacturer. Trench backfill should be compacted in accordance with

Section 9.1.9 of this report. Trench backfill should be compacted by mechanical means.

Densification of trench backfill by flooding or jetting is not recommended.

To reduce potential for moisture intrusion into building envelopes, we recommend

plugging utility trenches at locations where the trench excavations cross under building

perimeters. The trench plug should be constructed of a compacted, fine-grained,

cohesive soil that fills the cross-sectional area of the trench for a distance equivalent to

the depth of the excavation. Alternatively, the plug may be constructed of lean concrete,

Controlled Low Strength Material (CLSM), or Flowable Fill.



9.1.6. Material Requirements

Materials used during earthwork, grading, and paving operations should comply with

the requirements listed in Table 5. Materials should be evaluated by the geotechnical

consultant for suitability prior to use. The contractor should notify the geotechnical con-

sultant 72 hours prior to import of materials or use of on-site materials to permit time

for sampling, testing, and evaluation of the proposed materials.



Table 5 – Recommended Material Requirements

Material and Use Source Requirements1,2

Import or On-site borrow Expansion Index 50 or less5 Select Structural Fill below footings and slabs behind retaining walls

On-site borrow (treated with lime) Plasticity Index 10 or less

General Fill for uses not otherwise specified On-site borrow No additional requirements1

Aggregate Base for pavements Import Class II; CSS4 Section 26-1.02

Asphalt Concrete for pavements Import Type B; CSS4 Section 39-2

Capillary Break Gravel part of vapor retarding system below select slabs-on-grade

Import Open-graded, clean, crushed rock

or angular gravel; nominal size 3/4” or less

Vapor Retarding Membrane Import 15 mil, Class A plastic membrane as per ASTM E 1745

Pipe/Conduit Bedding Material below conduit invert to 12 inches above conduit

Import 90 to 100 percent (by mass) should

pass No. 4 sieve, and 5 percent or less should pass No. 200 sieve

Trench Backfill above bedding material Import or on-site borrow

Free from rock/lumps in excess of 4” diameter or 2” diameter in top 12”;

As per select fill in top 3 feet 1 In general, fill should be free of rocks or lumps in excess of 6-inches diameter, trash, debris, roots, vegetation or

other deleterious material. 2 In general, import fill should be tested or documented to be non-corrosive3 and free from hazardous materials in

concentrations above levels of concern. 3 Non-corrosive as defined by the Corrosion Guidelines version 1.0 (Caltrans, 2003). 4 CSS is California Standard Specifications (Caltrans, 2006) 5 Placed below a plane extending down and away from the outer edges of footings/slabs at 2:1 angle.

9.1.7. Lime Treatment of Expansive Soils

In lieu of importing select material or locating on-site borrow with low expansion char-

acteristics, on-site material may be mixed with lime to create a 3-foot thick zone of low

expansion potential material below the building foundation elements and 2-foot thick

zone below exterior flatwork. On-site materials containing roots or other organic matter

are not suitable for lime treatment and should be stripped from the area at which the

lime treatment is to be performed. A specialty contractor should be consulted to select

the lime content and mixing procedure to reduce the plasticity index of the treated soil

to 10 or less. The lime or selected stabilizing agent may be spread in dry form or as



slurry. Dry lime should be spread and mixed in a fashion that reduces potential for dust-

ing. Casting or tailgating of dry lime is not recommended. The spreading and mixing

procedure should produce a consistent distribution of stabilizing agent in the treated

soil. Mixing and pulverizing should continue until the treated soil does not contain un-

treated soil clods larger than 1 inch and the quantity of untreated soil clods retained on

the No. 4 sieve is less than 40 percent of the dry soil mass. Periodic testing should be

performed to evaluate the plasticity index of the treated soil.

9.1.8. Subgrade Preparation

Subgrade below footings, slabs, pavement, walkways or fill, should be prepared as per

the recommendations in Table 6.

Table 6 – Subgrade Preparation Recommendations

Subgrade Location Preparation Recommendations

Utility Trenches o Do not scarify. Compact as per Section 9.1.9 if disturbed. Remove or com-pact loose/soft material.

Below Slabs, Walk-ways, Flatwork

o Remove unsuitable materials as per Sections 9.1.1 and 9.1.2. o Remove and replace expansive soil as per Section 9.1.2 or lime treat as per

Section 9.1.7. o Keep in moist but not saturated condition by sprinkling water.

Below Footings

o Remove unsuitable materials as per Section 9.1.2. o Remove or moisture condition and compact loose or soft subgrade material

as per Section 9.1.9. o Keep in moist condition by sprinkling water.

Below Fill

o Remove unsuitable materials as per Sections 9.1.1 and 9.1.2. o Scarify top 8” then moisture condition and compact as per Section 9.1.9. o Keep in moist but not saturated condition by sprinkling water.

Prepared subgrade should be maintained in a moist (but not saturated) condition by the

periodic sprinkling of water prior to placement of additional overlying fill or construc-

tion of pavements, footings and slabs. Subgrade that has been permitted to dry out and

loosen or develop desiccation cracking, should be scarified, moisture conditioned, and

recompacted as per the requirements above.



9.1.9. Fill Placement and Compaction

Fill and backfill should be compacted in horizontal lifts in conformance with the rec-

ommendations presented in Table 7. The allowable uncompacted thickness of each lift

of fill depends on the type of compaction equipment utilized, but generally should not

exceed 8 inches in loose thickness. Heavy compaction equipment should not be used in

the zone of influence behind retaining walls. The zone of influence is the region above a

plane extending up and away from the heel of the wall at a slope of about 2:1 (horizon-

tal to vertical).



Table 7 – Recommended Compaction Requirements

Fill Type Location Recommended

Compacted Density1

Recommended Compacted Moisture2

Below pavements and sidewalks 95 percent At or near optimum Subgrade Below fill, structures3, and walk-

ways 90 percent At or near optimum

Conduit Bedding Material below conduit invert to 12 inches above conduit 90 percent At or near optimum

3ft below pavements & sidewalks 95 percent At or near optimum Trench Backfill

In locations not already specified 90 percent At or near optimum

Below pavements and sidewalks 95 percent At or near optimum Select Fill

Below structures3, and walkways 90 percent At or near optimum

Aggregate Base Pavements, walkways & sidewalks 95 percent At or near optimum

Asphalt Concrete Pavements, walkways & sidewalks 95 percent Not Applicable

5 feet below finished grade 95 percent At or near optimum General Fill

Within 5 feet of finished grade 90 percent At or near optimum 1 Expressed as percent relative compaction or ratio of field density to reference density (typically on a

dry density basis for soil and aggregate and on a wet density basis for asphalt concrete). The refer-ence density of soil and aggregate should be evaluated by the latest version of ASTM D 1557. The reference density of asphalt concrete should be evaluated by California Test Method 304.

2 Optimum moisture should be evaluated by latest version of ASTM D 1557. 3 Placed below a plane extending down and away from the outer edges of footings/slabs at 1:1 angle.

Compacted fill should be maintained in a moist (but not saturated) condition by the

periodic sprinkling of water prior to placement of additional overlying fill or

construction of footings and slabs. Fill that has been permitted to dry out and loosen or

develop desiccation cracking, should be scarified, moisture conditioned, and

recompacted as per the requirements above.

9.1.10. Rainy Weather Considerations

We recommend that construction be performed during the period between approxi-

mately April 15 and October 15 to avoid the rainy season. In the event that grading is

performed through the rainy season, the plans for the project should be supplemented to



include a stormwater management plan prepared in accordance with the requirements of

the relevant agency having jurisdiction. The plan should include details of measures to

protect the subject property and adjoining off-site properties from damage by erosion,

flooding or the deposition of mud, debris, or construction-related pollutants, which may

originate from the site or result from the grading operation. The protective measures

should be installed by the commencement of grading, or prior to the start of the rainy

season. The protective measures should be maintained in good working order unless the

drainage system is installed by that date and approval has been granted by the building

official to remove the temporary devices.

In addition, construction activities performed during rainy weather may impact the

stability of excavation subgrade and exposed ground. Temporary swales should be

constructed to divert surface runoff away from excavations and slopes. Steep temporary

slopes should be covered with plastic sheeting during significant rains. The

geotechnical engineer should be consulted for recommendations to stabilize the site as

needed.

9.2. Foundations

The following foundation design parameters and recommendations are provided based on

our geotechnical analysis. The foundation design parameters are not intended to preclude

differential movement of soils. Minor cracking (considered tolerable) of foundations may

occur. Foundations should be designed in accordance with structural considerations and our

geotechnical recommendations. In addition, the requirements of the governing jurisdictions,

the practices of the Structural Engineers Association of California, and applicable building

codes should be considered in the design of the structure.

9.2.1. Slab-On-Grade Foundations

Structural loads for the Science Technology Phase II building may be supported on a

slab-on-grade foundation consisting of wall and column footings to carry structural



loads with an interior slab-on-grade floor. The parameters listed in Table 8 should be

used to design footings to resist vertical loads provided that unsuitable materials are

removed from the zone of influence below the footings as per Section 9.1.2 and the

subgrade is prepared in accordance with the recommendations in Section 9.1.8. The

geotechnical consultant should be provided an opportunity to observe the footing

excavations to check that the actual bearing depth and exposed bearing materials are

consistent with the assumed values. The thickness of unsuitable materials to be removed

might exceed the assumed bearing depth. Footings should be deepened as needed to

bear on suitable materials under the direction of the geotechnical engineer.

Alternatively, the deepened footing trenches may be backfilled partially with CLSM to

achieve the recommended bearing depth.

Table 8 – Recommended Bearing Design Parameters for Footings

Supported Structure

Assumed Bearing Material

Footing Width

Bearing Depth1

D

Allowable Bearing

Capacity2 qa

Science Technology Phase II column footing

24 inches or more

Science Technology Phase II wall footing

Engineered Fill or Lime Treated Soil

18 inches or more

24 inches 2,500 psf

1 Below the adjacent grade. Extend footing, as needed, to bear on native soil to mitigate differential fill/native bearing condition (see text).

2 Listed value includes a FOS of 3. Allowable bearing capacity may be increased by one-third when considering loads of short duration such as wind or seismic loads.

To mitigate potential differential settlement or ground motion incoherence due to a

mixed fill - native soil bearing condition or significant differences in fill thickness

below footings, footings should extend below the fill to bear on engineered fill or lime

treated soil, as needed. Alternatively, the thickness of fill below portions of the

foundation may be increased by excavation and recompaction as per Section 9.1.2.



Structures should be designed to withstand total and differential settlements equivalent

to ½-inch and ¼-inch, respectively. The modulus of subgrade values listed in Table 9

may be used to evaluate deflection.

Where footings are located adjacent to a trench or excavation that is nearly parallel to

the footing alignment, the footing bearing surfaces should bear below an imaginary

plane extending upward from the bottom edge of the adjacent trench/excavation at a

2:1 angle. Footings should be deepened or excavation depths reduced as needed.

We recommend that footings and slabs be reinforced with deformed steel bars of suffi-

cient rigidity to maintain the desired position within the footing or slab for a reasonable

amount of support. We recommend that masonry briquettes or plastic chairs be used to

aid in the correct placement of reinforcement. Footings and slabs should be designed by

the structural engineer based on the anticipated loading and usage. Refer to Section 9.5

for the recommended concrete cover over reinforcing steel.

Table 9 – Modulus of Subgrade Reaction for Footings

Footing Width (feet)

Modulus of Subgrade Reaction (pci)

1.5 150 Wall Footing

5 75

2 170 Column Footing

10 70

Note: “pci” is pounds per cubic inch

Slabs underlying enclosed spaces with humidity conditioned environments or slabs cov-

ered by moisture sensitive floor coverings should incorporate a moisture vapor

retarding system into the design. See Section 9.6 for vapor retarding system recommen-

dations.



9.2.2. Lateral Resistance of Shallow Foundations

The parameters listed in may be used to evaluate the capacity of shallow foundations to

resist lateral loads on the proposed project.

Table 10 – Recommended Lateral Design Parameters for Shallow Foundations

Allowable Lateral Resistance1

Supported Structure

Assumed Bearing Material

Assumed Lateral Bearing Material

Friction Coefficient2

tan(δ)

Base Adhesion2

ca

Lateral Fluid

Pressure3 γep

Select Fill or Lime Treated Soil 0.35 -- 350 pcf Science Technology

Phase II Foundations Moisture Vapor Retarder 0.20 -- 350 pcf

1 Allowable lateral resistance can be taken as the sum of the lateral bearing and lateral sliding resistance provided that the lateral bearing does not exceed two-thirds the total allowable lateral resistance. The lateral resistance may be increased by one-third for load combinations including wind or seismic loads.

2 Lateral sliding resistance is the product of the friction coefficient and the base contact pressure or the product of the base adhesion and the base contact area, whichever is larger. Assumes that slabs or foot-ings are poured rough against the subgrade and slabs have thickened edges. Lateral sliding resistance may not exceed one-half the dead load.

3 Lateral bearing resistance is the product of the lateral fluid pressure, the depth of embedment, and the lateral contact area, neglecting the top foot of embedment unless confinement is provided by an adja-cent slab or pavement. The lateral fluid pressure does not include a FOS. The depth of embedment for lateral bearing resistance on sloping ground should be evaluated at a distance away from the footing equivalent to 300 percent of the footing embedment depth next to the footing. The designer should as-sume that the lateral bearing pressure does not increase below a depth of 10 feet.

9.2.3. Uplift Anchors

Uplift anchors, if needed to resist seismic loads, may be designed for an allowable skin

friction of 300 pounds per square foot.

9.3. Seismic Design Considerations

Criteria for seismic design including parameters to model earthquake ground motion and

building response consistent with Section 1613A of the 2007 CBC (CBSC, 2007) are

presented in the following table. Spectral acceleration ordinates are presented in the table for

the mapped MCE values with a recurrence interval of 2,500 years and assumed 5 percent

damping. A site-specific ground motion hazard analysis conforming with Section 21.2 of



ASCE 7-05 (ASCE, 2006) was performed in accordance with Section 1614A of the CBC

since the site is within 10 km of an active fault. The results of the analysis are presented on

Figure 6. The analysis is further documented in Section 7.1.3 of this report. The spectral

acceleration ordinates for site soil conditions based on this analysis and scaled for design

with a factor of two-thirds are also presented in the following table. These ordinates from

the site-specific ground motion hazard analysis exceed 80 percent of the site-adjusted and

design scaled ordinates computed from the mapped MCE values in accordance with Section

21.4 of ASCE 7-05.

Table 11 – 2007 California Building Code Seismic Design Criteria

Seismic Design Factor Value

Mapped MCE Spectral Acceleration at period of 0.2 seconds, SS 1.53 Mapped MCE Spectral Acceleration at period of 1 second, S1 0.60 Soil Profile Type D Site Coefficient Fa 1.0 Site Coefficient Fv 1.5 Site-Adjusted MCE Spectral Acceleration at period of 0.2 seconds, SMS 2.05 Site-Adjusted MCE Spectral Acceleration at period of 1 second, SM1 1.07 Design Spectral Acceleration at period of 0.2 seconds, SDS 1.37 Design Spectral Acceleration at period of 1 second, SD1 0.71 Seismic Design Category D

9.4. Preliminary Pavement Design

Recommendations for pedestrian walkways/sidewalks are presented in the following

paragraphs.

Pedestrian sidewalks (adjacent to pavements) and walkways (removed from pavements carry-

ing vehicular traffic) may be constructed of asphalt or Portland cement concrete. Asphalt

concrete walkways should consist of 2 inches asphalt concrete over 4 inches of aggregate

base. Portland cement concrete walkways should consist of 4 inches of concrete over 4 inches

of aggregate base. These sections presume that the onsite expansive soils in the subgrade are



mitigated by removal and replacement or lime treatment in accordance with our recommenda-

tions in Sections 9.1.2 and 9.1.7, respectively, and the subgrade is prepared in accordance with

our recommendations in Section 9.1.8. Asphalt concrete, Portland cement concrete, and aggre-

gate base materials should comply with our recommendations in the preceding sections.

Aggregate base sections for walkways and sidewalks should be compacted in accordance with

our recommendations in Section 9.1.9.

Portland cement concrete sidewalks and walkways should be appropriately jointed to reduce

the random occurrence of cracks. Joints should be laid out in a regular square pattern. Con-

traction, construction, and isolation joints should be detailed and constructed in accordance

with the guidelines of ACI Committee 302 (MCP, 2007). We recommend spacing contrac-

tion joints at 8 feet, or less.

9.5. Concrete

Laboratory testing indicated that the concentration of sulfate and corresponding potential for

sulfate attack on concrete is negligible for the soil tested. However, due to the variability in

the on-site soils and the potential future use of reclaimed water at the site, we recommend

that Type V cement be used for concrete structures in contact with soil. In addition, we

recommend a water-to-cement ratio of 0.45, or less. A 3-inch thick, or thicker, concrete

cover should be maintained over reinforcing steel where concrete is in contact with soil in

accordance with Section 7.7 of ACI Committee 318 (ACI, 2007).

In order to reduce the potential for shrinkage cracks in the concrete during curing, we

recommend that the concrete for slabs, flatwork, or pavement should not contain large

quantities of water or accelerating admixtures containing calcium chloride. Higher

compressive strengths may be achieved by using larger aggregates in lieu of increasing the

cement content and corresponding water demand. Additional workability, if desired, may be

obtained by including water-reducing or air-entraining admixtures. Concrete for slabs,

flatwork, or pavement should have a slump of 4 inches or less, as evaluated by ASTM

Standard C143, before admixtures are added. The slump should be checked at the site by a



representative of Ninyo & Moore or other qualified materials testing laboratory prior to

placement. Concrete should be placed in accordance with ACI MCP and project

specifications. Particular attention should be given to curing techniques and curing duration.

Slabs that do not receive adequate curing have a more pronounced tendency to develop

random shrinkage cracks and other defects.

9.6. Moisture Vapor Retarder

The migration of moisture through slabs underlying enclosed spaces or overlain by moisture

sensitive floor coverings should be limited by providing a moisture vapor retarding system

between the subgrade soils and the bottom of slabs. We recommend that the moisture vapor

retarding system consist of a 4-inch thick capillary break, overlain by a plastic membrane

15 mil thick with a 2-inch thick clean blotter sand cover over the membrane. The capillary

break should be constructed of clean, open-graded crushed rock or angular gravel of ¾-inch

nominal size. The plastic membrane should conform to the requirements in the latest version

of ASTM Standard E 1745 for a Class A membrane. The blotter sand should be in a moist

but not saturated condition prior to concrete placement. The bottom of the moisture barrier

system should be higher in elevation than the exterior grade, if possible. Positive drainage

should be established and maintained adjacent to foundations and flatwork.

A subdrain should be constructed around the foundation perimeter at locations where the ex-

terior grade is at a higher elevation than the moisture vapor retarding system (including the

capillary break layer). The subdrain should consist of ¾-inch crushed rock wrapped in filter

fabric (Mirafi 140N, or equivalent). The subdrain should be capped by a pavement or

12 inches of native soil and drained by a perforated pipe (Schedule 40 PVC pipe, or similar).

The pipe should be sloped at 1 percent or more to discharge at an appropriate outlet away

from the foundation. The pipe should be located below the bottom elevation of the moisture

vapor retarding system but above a plane extending down and away from the bottom edge of

the foundation at a 2:1 (horizontal to vertical) gradient.



9.7. Drainage and Site Maintenance

Surface drainage on the site should generally be provided so that water is diverted away

from structures and slopes and is not permitted to pond. Positive drainage consisting of a

gradient of 2 percent or more should be established over the pad and for a distance of 5 feet

or more adjacent to structures and sloped to divert surface water to an appropriate collector

(graded swale, v-ditch, or area drain) with a suitable outlet. Roof, slope, and pad drainage

should be collected and diverted to suitable discharge areas away from structures or other

slopes by non-erodible devices (e.g., gutters, downspouts, concrete swales, etc.). Graded

swales, v-ditches, or curb and gutter should be provided at the site perimeter to restrict flow

of surface water onto and off of the site. Slopes should be vegetated or otherwise armored to

reduce potential for erosion of soil. Drainage structures should be periodically cleaned out

and repaired, as needed, to maintain appropriate site drainage patterns.

Care should be taken by the contractor during grading to preserve any berms, drainage ter-

races, interceptor swales or other drainage devices on or adjacent to the property. Drainage

patterns established at the time of grading should be maintained for the life of the project.

The property owner and maintenance personnel should be made aware that altering drainage

patterns might be detrimental to foundation performance.

9.8. Review of Construction Plans

The recommendations provided in this report are based on preliminary design information

for the proposed construction. We recommend that the geotechnical consultant review

project plans. It should be noted that upon review of these documents, some

recommendations presented in this report might be revised or modified to meet the project

requirements.

9.9. Pre-Construction Conference

We recommend that a pre-construction conference be held. Owner representatives, the

architect, the structural engineer, the civil engineer, the geotechnical consultant, and the



contractor should be in attendance to discuss the plans, the project, and the proposed

construction schedule.

9.10. Construction Observation and Testing

The recommendations provided in this report are based on subsurface conditions disclosed

by widely spaced exploratory borings. The geotechnical consultant in the field during

construction should check the interpolated subsurface conditions. During construction, the

geotechnical consultant should:

• Observe excavation of unsuitable materials.

• Check and test imported materials prior to their use as fill.

• Observe lime-treatment of on-site soils.

• Observe placement and compaction of fill.

• Perform field density tests to evaluate fill compaction.

• Observe slab subgrade and footing excavations for bearing materials and cleaning prior to placement of reinforcing steel and concrete.

• Observe condition of water vapor retarding system prior to concrete placement.

The recommendations provided in this report assume that Ninyo & Moore will be retained

as the geotechnical consultant during the construction phase of the project. If another geo-

technical consultant is selected, we request that the selected consultant provide a letter to the

architect and the owner (with a copy to Ninyo & Moore) indicating that they fully under-

stand Ninyo & Moore’s recommendations, and that they are in full agreement with the

recommendations contained in this report.



10. LIMITATIONS

The field evaluation, laboratory testing, and geotechnical analyses presented in this geotechnical

report have been conducted in general accordance with current practice and the standard of care

exercised by geotechnical consultants performing similar tasks in the project area. No warranty,

expressed or implied, is made regarding the conclusions, recommendations, and opinions pre-

sented in this report. There is no evaluation detailed enough to reveal every subsurface condition.

Variations may exist and conditions not observed or described in this report may be encountered

during construction. Uncertainties relative to subsurface conditions can be reduced through addi-

tional subsurface exploration. Additional subsurface evaluation will be performed upon request.

Please also note that our evaluation was limited to assessment of the geotechnical and geologic

aspects of the project, and did not include evaluation of structural issues, environmental con-

cerns, or the presence of hazardous materials.

This document is intended to be used only in its entirety. No portion of the document, by itself, is

designed to completely represent any aspect of the project described herein. Ninyo & Moore

should be contacted if the reader requires additional information or has questions regarding the

content, interpretations presented, or completeness of this document.

This report is intended for design purposes only. It does not provide sufficient data to prepare an

accurate bid by contractors. It is suggested that the bidders and their geotechnical consultant per-

form an independent evaluation of the subsurface conditions in the project areas. The independent

evaluations may include, but not be limited to, review of other geotechnical reports prepared for the

adjacent areas, site reconnaissance, and additional exploration and laboratory testing.

Our conclusions, recommendations, and opinions are based on an analysis of the observed site

conditions. If geotechnical conditions different from those described in this report are encountered,

our office should be notified and additional recommendations, if warranted, will be provided upon

request. It should be understood that the conditions of a site could change with time as a result of

natural processes or the activities of man at the subject site or nearby sites. In addition, changes to

the applicable laws, regulations, codes, and standards of practice may occur due to government



action or the broadening of knowledge. The findings of this report may, therefore, be invalidated

over time, in part or in whole, by changes over which Ninyo & Moore has no control.

This report is intended exclusively for use by the District. Any use or reuse of the findings, con-

clusions, and/or recommendations of this report by parties other than the District is undertaken at

said parties’ sole risk.



11. REFERENCES

American Concrete Institute, 2007, ACI Manual of Concrete Practice.

American Society for Testing and Materials (ASTM), 2007, Annual Book of ASTM Standards, West Conshohocken, Pennsylvania.

American Society of Civil Engineers (ASCE), 2006, Minimum Design Loads for Buildings and Other Structures, Standard 7-05.

Association of Bay Area Governments, 2004, Bay Area Dam Failure Inundation Maps: http://www.abag.ca.gov/bayarea/eqmaps/damfailure/dfpickc.html

Blake, T.F., 2001, FRISKSP (Version 4.00), A Computer Program for the Probabilistic Estimation of Peak Acceleration and Uniform Hazard Spectra Using 3-D Faults as Earthquake Sources.

Bortugno, E.J., McJunkin, R.D., and Wagner, D.L., 1991, Map Showing Recency of Faulting, San Francisco-San Jose Quadrangle, California, California Department of Conservation, Division of Mines and Geology, Regional Geologic Map Series: Map No. 5A, Sheet 5, Scale 1:250,000.

Bozorgnia, Y., Campbell, K.W., and Niazi, M., 1999, Vertical Ground Motion: Characteristics, Relationship with Horizontal Component, and Building Code Implications, Proceedings of the SMIP99 Seminar on Utilization of Strong-Motion Data, Oakland, pp. 23-49, September 15.

Bray, J.D., and Sancio, R.B., 2006, Assessment of the Liquefaction Susceptibility of Fine-Grained Soils, Journal of Geotechnical and Geoenvironmental Engineering, American Society of Civil Engineers (ASCE), Vol. 132, No. 9, pp. 1165-1177.

California Building Standards Commission (CBSC), 2007, California Building Code (CBC), Title 24, Part 2, Volumes 1 and 2.

California Department of Transportation (Caltrans), 2003, Corrosion Guidelines, Version 1.0, Division of Engineering Services, Materials Engineering and Testing Services, Corrosion Technology Branch: dated September.

California Department of Transportation (Caltrans), 2006, California Test Methods (CTM), http://www.dot.ca.gov/hq/esc/ctms/index.html, dated November 20.

California Department of Transportation (Caltrans), 2006, Standard Specifications: dated May.

California Department of Transportation (Caltrans), 2007, Highway Design Manual, http://www.dot.ca.gov/hq/oppd/hdm/hdmtoc.htm, dated January 4.



California Division of Mines and Geology (CDMG), 1980, California Geology: The Livermore Earthquake of January 1980, Contra Costa and Alameda Counties, California, April 1980, Volume 33, No. 4.

California Division of Mines and Geology, 1982, State of California Special Studies Zones, Livermore Quadrangle: dated January 1: scale 1:24,000.

California Geological Survey, 2008a, Seismic Hazard Zone Report for the Livermore 7.5-Minute Quadrangle, Alameda County, California, Seismic Hazard Zone Report 114.

California Geological Survey, 2008b, Seismic Hazard Zone Map for the Livermore 7.5-Minute Quadrangle, Alameda County, California, Scale: 1:24,000, dated August 27.

California Geological Survey, 2007, Note 48, Checklist for Review of Engineering Geology and Seismology Reports for California Public Schools, Hospitals, and Essential Services Buildings: dated October.

Cao, T., Bryant, W.A., Rowshandel, B., Branum, D., and Wills, C. J., 2003, The revised 2002 California Probabilistic Seismic Hazard Maps, California, USGS/CGS: dated June.

Crane, R.C., 1995, Geology of Mount Diablo Region and East Bay Hills; in Recent Geological Studies of the San Francisco Bay Area, SEPM, Pacific Section, Vol. 76, p 87-114: scale 1:24,000.

Dibblee, T.W., 2006, Geologic Map of the Livermore Quadrangle, Contra Costa and Alameda Counties, California: scale 1:24,000; Dibblee Geology Center Map #DF-196.

Ellen, S.D., and Wentworth, C.M., 1995, Hillside Materials and Slopes of the San Francisco Bay Region, California, United States Geological Survey Professional Paper 1357.

ESRI/FEMA Hazard Information and Awareness Site, 2007: http://www.esri.com/hazards/ makemap.html

Federal Emergency Management Agency (FEMA), 1997, Flood Insurance Rate Map, City of Livermore, California, Panel 5 of 10, Community Parcel Number 06008 0005 B, dated September 17.

Graymer, R.W., Jones, D.L., and Brabb, E.E., 1996, Preliminary Geologic Map Emphasizing Bedrock Formations in Alameda County, California, USGS, OFR 96-252, scale 1:75:000.

Gregory, G.H., 2003, GSABL7 with STEDwin Slope Stability Analysis System, version 2.004.

Herd, D.G., 1977, Geologic Map of the Las Positas, Greenville, and Verona Faults, Eastern Alameda County, California, USGS OFR 77-689: Scale 1:24,000.

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, scale 1:750,000.



Kwan Henmi Architecture/Planning Inc., 2009, Site Plan, Las Positas Community College, Livermore, California: Project No. 0903.00, Sheet A1.00a, dated May 2009.

Leidenfrost/Horowitz & Associates, Inc., 2006, First Floor Plan, Las Positas College, Livermore, California, dated May 2006.

Majmunder, H., 1991, Landslide Hazards in the Livermore Valley and Vicinity, Alameda and Contra Costa Counties, California: CDMG Landslide Hazard Identification Map 21 DMG OFR 91-2: scale 1:24,000.

Nilsen, T.H., 1975, Preliminary Photointerpretation Map of Landslide and Other Surficial Deposits, The Livermore 7.5’ Quadrangle, Alameda County, California, USGS OFR 75-277: Scale 1:24,000.

Ninyo & Moore, 2007a, Potential Fault Evaluation Study, Las Positas Community College, Livermore, California: Project No. 401294005: dated August 24.

Ninyo & Moore, 2007b, Geologic Hazards Assessment and Geotechnical Evaluation, Child Development Center, Las Positas College, Livermore, California: Project No. 401337001: dated November 1.

Ninyo & Moore, 2008a, Proposal for Geotechnical Evaluation and Geologic Hazard Assessment, Phase III Athletics Development at Las Positas College, Livermore, California: Proposal No. P-81001: dated January 31.

Ninyo & Moore, 2008b, Geologic Hazards Assessment and Geotechnical Evaluation, Student and Administrative Services Building, Las Positas College, Livermore, California: Project No. 401426001: dated June 17.

Occupational Safety and Health Administration (OSHA), 1989, Occupational Safety and Health Standards – Excavations, Department of Labor, Title 29 Code of Federal Regulations (CFR) part 1926, dated October 31.

Sadigh, K., Chang, C.Y., Egan, J.A., Makdisi, F., and Youngs, R.R., 1997, Attenuation Relationships for Shallow Crustal Earthquakes Based on California Strong Motion Data, Seismological Research Letters, Volume 68, Number 1, January/February.

Scheimer, J.F, Taylor, S.R., and Sharp, M., 1982, Seismicity of the Livermore Valley Region, 1969-1981; in Hart, E.W, Hirschfeld, S.E., Schulz, S.S., 1982, Proceedings: Conference on Earthquake Hazards in the Eastern San Francisco Bay Area: CDMG Special Publication 62.

United States Geological Survey (USGS), 2008a, USGS National Earthquake Information Center, http://neic.usgs.gov/.

United States Geological Survey (USGS), 2008b, Earthquake Hazards Program, Historic Earthquakes, http://earthquake.usgs.gov/regional/states/events/1980_01_24.php.



AERIAL PHOTOGRAPHS Source Date Flight Numbers Scale

Pacific Aerial Surveys 5-2-05 KAV9015-336 4, 5, 6 1:7,200 Pacific Aerial Surveys 5-7-01 KAV6977-14 2, 3, 4 1:7,200 Pacific Aerial Surveys 8-20-99 AV6100-131 37, 38 1:12,000 Pacific Aerial Surveys 7-31-96 AV5200 35, 36 1:12,000 Pacific Aerial Surveys 6-2-94 AV4624-32 34, 35 1:12,000 Pacific Aerial Surveys 7-22-92 AV4230-132 36, 37 1:12,000 Pacific Aerial Surveys 7-23-90 AV3845-29 41, 42 1:12,000 Pacific Aerial Surveys 4-20-86 AV2862-05 12, 13 1:12,000 Pacific Aerial Surveys 4-30-80 AV1860-05 12, 13 1:12,000 Pacific Aerial Surveys 4-12-71 AV994-02 11, 12 1:12,000 Pacific Aerial Surveys 5-15-69 AV903-05 12, 13 1:12,000 Pacific Aerial Surveys 5-16-57 AV253-30 37, 38, 39 1:12,000

PROJECT NO.

REGIONAL GEOLOGIC MAP

3DATE

FIGURE

APPROXIMATE SCALE IN FEET

1250062500

SURFICIAL DEPOSITS, UNDIVIDED

LIVERMORE GRAVELS

GREEN VALLEY AND TASSAJARA FORMATIONS, UNDIVIDED

LEGEND

N

SITE

NOTE: ALL DIMENSIONS, DIRECTIONS AND LOCATIONS ARE APPROXIMATE.

Qu

QTI

Tgvt

REFERENCE: GRAYMER, R.W., JONES, D.L. & BRABB, E.E, 1996, PRELIMINARY GEOLOGIC MAP EMPHASIZING BEDROCKFORMATIONS IN ALAMEDA COUNTY, CALIFORNIA, UNITED STATES GEOLOGICAL SURVEY OFR 96-252; SCALE 1:175,000.

401294018 6/09

SCIENCE TECHNOLOGY PHASE IILAS POSITAS COMMUNITY COLLEGE

LIVERMORE, CALIFORNIA

Deterministic MCE Probabilistic MCE Site Specific MCE Site Specific Design

0.51

T (sec) Sa (g) T (sec) Sa (g) T (sec) Sa (g) T (sec) Sa (g)

0.01

1.37

1.03

0.87

0.51

2.04

0.71

0.91

1.15

1.27

1.36

1.72

0.49

0.71

1.07

1.36

0.20

0.10

0.08

0.03

0.75

0.50

0.40

0.30

1.31

0.76

0.76

2.00

1.50

1.00

1.90

2.04

2.05

1.55

0.01

0.61

0.84

1.17

1.39

1.72

0.20

0.10

0.08

0.03

0.75

0.50

0.40

0.30

1.50

1.50

1.50

2.00

1.50

1.00

0.01

0.00

0.49

0.71

0.30

0.20

0.10

0.08

1.00

0.75

0.50

0.40

2.00

1.50

1.07

2.05

1.55

1.31

1.36

1.72

1.94

2.15

2.18

1.72

0.76

2.00

1.50

1.00

0.75

1.90

6LAS POSITAS COMMUNITY COLLEGE

0.50

0.40

0.33

0.47

401294018 6/09 LIVERMORE, CALIFORNIA

SCIENCE TECHNOLOGY PHASE II

0.30

0.20

0.10

0.08

0.03

0.01

0.76

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

2.2

2.4

2.6

2.8

3.0

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

PERIOD, T (seconds)

SP

EC

TR

AL A

CC

ELE

RA

TIO

N, S

a (

g)

CBC Type D soil, Design Curve

80% CBC Design Curve

Probabilistic MCE Curve (Sadigh et al. 1997 Deep Soil)

Deterministic MCE Curve (Sadigh et al. 1997 Deep Soil)

Site Specific MCE Curve

Site Specific Design Curve

SITE SPECIFIC ACCELERATION RESPONSE SPECTRA

PROJECT NO. DATE

FIGURE

FIG 6


401294018 R Geo Eval.doc

APPENDIX A

BORING LOGS

Field Procedure for the Collection of Disturbed Samples Disturbed soil samples were obtained in the field using the following methods.

Bulk Samples Bulk samples of representative earth materials were obtained from the exploratory borings. The samples were bagged and transported to the laboratory for testing.

The Standard Penetration Test (SPT) Sampler Disturbed drive samples of earth materials were obtained by means of a Standard Penetra-tion Test sampler. The sampler is composed of a split barrel with an external diameter of 2 inches and an unlined internal diameter of 1-3/8 inches. The sampler was driven into the ground 12 to 18 inches with a 140-pound hammer free-falling from a height of 30 inches in general accordance with ASTM D 1586. The blow counts were recorded for every 6 inches of penetration; the blow counts reported on the logs are those for the last 12 inches of pene-tration. Soil samples were observed and removed from the sampler, bagged, sealed and transported to the laboratory for testing.

Field Procedure for the Collection of Relatively Undisturbed Samples Relatively undisturbed soil samples were obtained in the field using the following methods.

The Modified Split-Barrel Drive Sampler The sampler, with an external diameter of 3.0 inches, was lined with 6-inch long, thin brass liners with inside diameters of approximately 2.4 inches. The sample barrel was driven into the ground with the weight of a hammer in general accordance with ASTM D 3550. The driving weight was permitted to fall freely. The approximate length of the fall, the weight of the hammer, and the number of blows per foot of driving are presented on the boring logs as an index to the relative resistance of the materials sampled. The samples were removed from the sample barrel in the brass liners, sealed, and transported to the laboratory for testing.

0

5

10

15

20

XX/XX

SM

Bulk sample.

Modified split-barrel drive sampler.

No recovery with modified split-barrel drive sampler.

Sample retained by others.

Standard Penetration Test (SPT).

No recovery with a SPT.

Shelby tube sample. Distance pushed in inches/length of sample recoveredin inches.

No recovery with Shelby tube sampler.

Continuous Push Sample.

Seepage.Groundwater encountered during drilling.Groundwater measured after drilling.

ALLUVIUM:Solid line denotes unit change.

Dashed line denotes material change.

Attitudes: Strike/Dipb: Beddingc: Contactj: Jointf: FractureF: Faultcs: Clay Seams: Shearbss: Basal Slide Surfacesf: Shear Fracturesz: Shear Zonesbs: Sheared Bedding Surface

The total depth line is a solid line that is drawn at the bottom of theboring.

BORING LOGEXPLANATION OF BORING LOG SYMBOLS

PROJECT NO. DATERev. 01/03

FIGURE

DE

PTH

(fee

t)

Bul

kSA

MPL

ESD

riven

BLO

WS

/FO

OT

MO

ISTU

RE

(%)

DR

Y D

ENSI

TY (P

CF)

SY

MB

OL

CLA

SS

IFIC

ATI

ON

U.S

.C.S

.

BORING LOG EXPLANATION SHEET

M AJOR DIVISIONS TYPICAL NAM ES

GW W ell graded gravels or gravel-sand mixtures, little or no fines

GP Poorly graded gravels or gravel-sand mixtures, little or no fines

GM Silty gravels, gravel-sand-silt mixtures

GC Clayey gravels, gravel-sand-clay mixtures

SW W ell graded sands or gravelly sands, little or no fines

SP Poorly graded sands or gravelly sands, little or no fines

SM Silty sands, sand-silt mixtures

SC Clayey sands, sand-clay mixtures

M L Inorganic silts and very fine sands, rock flour, silty or clayey fine sands or clayey silts with

CL Inorganic clays of low to medium plasticity, gravelly clays, sandy clays, silty clays, lean

OL Organic silts and organic silty clays of low plasticity

M H Inorganic silts, micaceous or diatomaceous fine sandy or silty soils, elastic silts

CH Inorganic clays of high plasticity, fat clays

OH Organic clays of medium to high plasticity, organic silty clays, organic silts

HIGHLY ORGANIC SOILS Pt Peat and other highly organic soils

SILTS & CLAYSLiquid Limit >50

U.S.C.S. M ETHOD OF SOIL CLASSIFICATION

GRAVELS(M ore than 1/2 of coarse

fraction > No. 4 sieve size)

SANDS(M ore than 1/2 of coarse

fraction <No. 4 sieve size)

SILTS & CLAYSLiquid Limit <50

SYM BOL

CO

AR

SE-G

RA

INED

SO

ILS

(Mor

e th

an 1

/2 o

f soi

l >N

o. 2

00 si

eve

size

)

FIN

E-G

RA

INED

SO

ILS

(Mor

e th

an 1

/2 o

f soi

l <N

o. 2

00 si

eve

size

)

GRAIN SIZE CHART

PLASTICITY CHART

RANGE OF GRAIN SIZE

CLASSIFICATION U.S. Standard

Sieve Size Grain Size in Millimeters

BOULDERS Above 12" Above 305

COBBLES 12" to 3" 305 to 76.2

GRAVEL Coarse

Fine

3" to No. 4 3" to 3/4"

3/4" to No. 4

76.2 to 4.76 76.2 to 19.1 19.1 to 4.76

SAND Coarse

Medium Fine

No. 4 to No. 200 No. 4 to No. 10 No. 10 to No. 40

No. 40 to No. 200

4.76 to 0.075 4.76 to 2.00

2.00 to 0.420 0.420 to 0.075

SILT & CLAY Below No. 200 Below 0.075

CH

CL M H & OH

M L & OLCL - M L

0

10

20

30

40

50

60

70

0 10 20 30 40 50 60 70 80 90 100LIQ UID LIMIT (LL), %

PLA

STIC

ITY

IND

EX (P

I), %

U.S.C.S. METHOD OF SOIL CLASSIFICATION

USCS Soil Classification Updated Nov. 2004

0

5

10

15

20

38

16

35

54

30

58

19.4 105.6

CL

ASPHALT CONCRETE: Approximately 6 inches thick.

AGGREGATE BASE: Approximately 12 inches thick.

ALLUVIUM:Brown, damp, very stiff, CLAY; some fine to coarse sand.

Trace caliche.

Little fine to medium sand.

Light brown, hard, some fine to coarse sand, little silt.

Very stiff, few gravel.

Yellowish brown, hard.

BORING LOGSCIENCE TECHNOLOGY PHASE II - LAS POSITAS COMMUNITY COLLEGE

LIVERMORE, CALIFORNIAPROJECT NO.

401294018DATE

6/09FIGURE

A-1

DE

PTH

(fee

t)

Bul

kSA

MPL

ESD

riven

BLO

WS

/FO

OT

MO

ISTU

RE

(%)

DR

Y D

ENSI

TY (P

CF)

PID

RE

AD

ING

(PP

M)

SYM

BOL

CLA

SS

IFIC

ATI

ON

U.S

.C.S

.

DESCRIPTION/INTERPRETATION

DATE DRILLED 5/21/09 BORING NO. B-1

GROUND ELEVATION 476' MSL SHEET 1 OF

METHOD OF DRILLING Mobile B-24, 8" Hollow Stem Auger (RAM)

DRIVE WEIGHT 140 lbs. (Cathead) DROP 30"

SAMPLED BY KAG LOGGED BY KAG REVIEWED BY MRC

3

20

25

30

35

40

58

47

32

52/6"

63/6"

CL

SC

CL

ALLUVIUM (continued):Yellowish brown, damp, hard, CLAY.

Brown, damp, dense clayey SAND; fine to coarse.

Light yellowish brown, damp, hard, CLAY; few fine sand; trace caliche.

Some fine to medium sand.

Hard drilling.

Light olive; few caliche.



401294018DATE

6/09FIGURE

A-2

DE

PTH

(fee

t)

Bul

kSA

MPL

ESD

riven

BLO

WS

/FO

OT

MO

ISTU

RE

(%)

DR

Y D

ENSI

TY (P

CF)

PID

RE

AD

ING

(PP

M)

SYM

BOL

CLA

SS

IFIC

ATI

ON

U.S

.C.S

.







3

40

45

50

55

60

34

32

CL ALLUVIUM (continued):Light olive, damp, hard, CLAY; some fine to medium sand; few caliche.

Yellowish brown.

Total depth = 50.5 feet.

Groundwater, though not encountered at the time of drilling, may rise to a higher leveldue to seasonal variations in precipitation and several other factors as discussed in thereport.

Backfilled with grout on 5/21/09.



401294018DATE

6/09FIGURE

A-3

DE

PTH

(fee

t)

Bul

kSA

MPL

ESD

riven

BLO

WS

/FO

OT

MO

ISTU

RE

(%)

DR

Y D

ENSI

TY (P

CF)

PID

RE

AD

ING

(PP

M)

SYM

BOL

CLA

SS

IFIC

ATI

ON

U.S

.C.S

.







3

0

5

10

15

20

23

15

33

28

39

23.3 95.5

CL

SC

CL

ASPHALT CONCRETE: Approximately 6 inches thick.AGGREGATE BASE: Approximately 12 inches thick.

ALLUVIUM:Light olive brown, damp, very stiff, CLAY; some fine sand; few silt; trace caliche.

Stiff to very stiff.

Very stiff.

Light to dark brown, damp, medium dense, silty fine to coarse SAND; trace caliche; littleclay.

Olive brown, damp, hard, silty CLAY; little fine sand; trace caliche.



401294018DATE

6/09FIGURE

A-4

DE

PTH

(fee

t)

Bul

kSA

MPL

ESD

riven

BLO

WS

/FO

OT

MO

ISTU

RE

(%)

DR

Y D

ENSI

TY (P

CF)

PID

RE

AD

ING

(PP

M)

SYM

BOL

CLA

SS

IFIC

ATI

ON

U.S

.C.S

.







2

20

25

30

35

40

Total depth = 20 feet.


Backfilled with grout on 5/21/09.



401294018DATE

6/09FIGURE

A-5

DE

PTH

(fee

t)

Bul

kSA

MPL

ESD

riven

BLO

WS

/FO

OT

MO

ISTU

RE

(%)

DR

Y D

ENSI

TY (P

CF)

PID

RE

AD

ING

(PP

M)

SYM

BOL

CLA

SS

IFIC

ATI

ON

U.S

.C.S

.







2

0

5

10

15

20

14

11

25

11

28

51/6"

17.0 107.8

CH

CL

SC

GRASS SURFACE:ALLUVIUM (overbank deposit):Dark brown, dry to damp, stiff CLAY.

ALLUVIUM:Yellowish brown, damp, stiff, CLAY; little silt; little fine to coarse sand.

Very stiff, some fine to medium sand.

Stiff.

Very stiff.

Light brown, damp, medium dense, clayey SAND; little silt.

Total depth = 19 feet.



401294018DATE

6/09FIGURE

A-6

DE

PTH

(fee

t)

Bul

kSA

MPL

ESD

riven

BLO

WS

/FO

OT

MO

ISTU

RE

(%)

DR

Y D

ENSI

TY (P

CF)

PID

RE

AD

ING

(PP

M)

SYM

BOL

CLA

SS

IFIC

ATI

ON

U.S

.C.S

.







2

20

25

30

35

40


Backfilled with cuttings on 5/21/09.



401294018DATE

6/09FIGURE

A-7

DE

PTH

(fee

t)

Bul

kSA

MPL

ESD

riven

BLO

WS

/FO

OT

MO

ISTU

RE

(%)

DR

Y D

ENSI

TY (P

CF)

PID

RE

AD

ING

(PP

M)

SYM

BOL

CLA

SS

IFIC

ATI

ON

U.S

.C.S

.







2


401294018 R Geo Eval.doc

APPENDIX B

LABORATORY TESTING

Classification Soils were visually and texturally classified in accordance with the Unified Soil Classification System (USCS) in general accordance with ASTM D 2488. Soil classifications are indicated on the logs of the exploratory borings in Appendix A.

Moisture Content The moisture content of selected samples obtained from the exploratory borings was evaluated in accordance with ASTM D 2216. The test results are presented on the logs of the exploratory bor-ings in Appendix A.

In-Place Moisture and Density Tests The moisture content and dry density of relatively undisturbed samples obtained from the ex-ploratory borings were evaluated in general accordance with ASTM D 2937. The test results are presented on the logs of the exploratory borings in Appendix A.

Atterberg Limits Tests were performed on a selected fine-grained soil sample to evaluate the liquid limit, plastic limit, and plasticity index in general accordance with ASTM D 4318. These test results were util-ized to evaluate the soil classification in accordance with the Unified Soil Classification System (USCS). The test results and classifications are shown on Figure B-1.

Unconfined Compression Tests Unconfined compression testing was performed on a relatively undisturbed sample in general accordance with ASTM D 2166. The test results are shown on Figure B-2.

Soil Corrosivity Tests Soil pH, and resistivity tests were performed on a soil sample in general accordance with California Test (CT) 643. The soluble sulfate and chloride content were evaluated in general accordance with CT 417 and CT 422, respectively. The test results are presented on Figure B-3.

PERFORMED IN GENERAL ACCORDANCE WITH ASTM D 2166

SCIENCE TECHNOLOGY PHASE IILAS POSITAS COMMUNITY COLLEGE

,

B-2

SampleLocation

CL

Symbol Description

YELLOWISH BROWN B-3

StrainRate

(%/min.)

UndrainShear Strsu, (ksf)

17.0 1.05 1.39107.8

SampleDepth(ft.)

MoistureContentw , (%)

6/09 LIVERMORE, CALIFORNIA401294018

DryDensityd, (pcf)

5.0 - 5.5

SoilType

0

0.5

1

1.5

2

2.5

3

0% 1% 2% 3% 4% 5% 6% 7% 8% 9% 10% 11% 12% 13% 14% 15%

AXIAL STRAIN

AXI

AL

CO

MPR

ESSI

VE S

TRES

S (K

IPS

PER

SQ

UA

RE

FOO

T)

UNCONFINED COMPRESSION RESULTSPROJECT NO. DATE

FIGURE

B-3 5.5'-6' UNCONFIN 5-21-09

Las Positas Community College Appendix C Livermore, California Project No. 401294018

APPENDIX C

TYPICAL EARTHWORK GUIDELINES


TYPICAL EARTHWORK GUIDELINES.doc Rev. 12/05 i

TABLE OF CONTENTS

Page 1. GENERAL................................................................................................................................1

2. OBLIGATIONS OF PARTIES ................................................................................................2

3. SITE PREPARATION .............................................................................................................3

4. REMOVALS AND EXCAVATIONS .....................................................................................4

5. COMPACTED FILL ................................................................................................................4

6. OVERSIZED MATERIAL ......................................................................................................7

7. SLOPES....................................................................................................................................8

8. TRENCH BACKFILL............................................................................................................10

9. DRAINAGE ...........................................................................................................................12

10. SITE PROTECTION..............................................................................................................12

11. DEFINITIONS OF TERMS...................................................................................................15

Figures Figure A – Fill Slope over Natural Ground or Cut Figure B – Transition and Undercut Lot Details Figure C – Canyon Subdrain Detail Figure D – Oversized Rock Placement Detail


TYPICAL EARTHWORK GUIDELINES.doc Rev. 12/05 1

TYPICAL EARTHWORK GUIDELINES

1. GENERAL

These guidelines and the standard details attached hereto are presented as general procedures for

earthwork construction for sites having slopes less than 10 feet high. They are to be utilized in

conjunction with the project grading plans. These guidelines are considered a part of the geo-

technical report, but are superseded by recommendations in the geotechnical report in the case of

conflict. Evaluations performed by the consultant during the course of grading may result in new

recommendations which could supersede these specifications and/or the recommendations of the

geotechnical report. It is the responsibility of the contractor to read and understand these guide-

lines as well as the geotechnical report and project grading plans.

1.1. The contractor shall not vary from these guidelines without prior recommendations by the geotechnical consultant and the approval of the client or the client’s authorized representative. Recommendations by the geotechnical consultant and/or client shall not be considered to preclude requirements for approval by the jurisdictional agency prior to the execution of any changes.

1.2. The contractor shall perform the grading operations in accordance with these specifications, and shall be responsible for the quality of the finished product notwithstanding the fact that grading work will be observed and tested by the geotechnical consultant.

1.3. It is the responsibility of the grading contractor to notify the geotechnical consultant and the jurisdictional agencies, as needed, prior to the start of work at the site and at any time that grading resumes after interruption. Each step of the grading operations shall be observed and documented by the geotechnical consultant and, where needed, reviewed by the appropriate jurisdictional agency prior to proceeding with subsequent work.

1.4. If, during the grading operations, geotechnical conditions are encountered which were not anticipated or described in the geotechnical report, the geotechnical consultant shall be notified immediately and additional recommendations, if applicable, may be provided.

1.5. An as-graded report shall be prepared by the geotechnical consultant and signed by a registered engineer and registered engineering geologist. The report documents the geotechnical consultants' observations, and field and laboratory test results, and provides conclusions regarding whether or not earthwork construction was performed in accordance with the geotechnical recommendations and the grading



plans. Recommendations for foundation design, pavement design, subgrade treatment, etc., may also be included in the as-graded report.

1.6. For the purpose of evaluating quantities of materials excavated during grading and/or locating the limits of excavations, a licensed land surveyor or civil engineer shall be retained.

1.7. Definitions of terms utilized in the remainder of these specifications have been provided in Section 11.

2. OBLIGATIONS OF PARTIES

The parties involved in the projects earthwork activities shall be responsible as outlined in the

following sections.

2.1. The client is ultimately responsible for each of the aspects of the project. The client or the client’s authorized representative has a responsibility to review the findings and recommendations of the geotechnical consultant. The client shall authorize the contractor and/or other consultants to perform work and/or provide services. During grading the client or the client’s authorized representative shall remain on site or remain reasonably accessible to the concerned parties to make the decisions that may be needed to maintain the flow of the project.

2.2. The contractor is responsible for the safety of the project and satisfactory completion of grading and other associated operations, including, but not limited to, earthwork in accordance with the project plans, specifications, and jurisdictional agency requirements. During grading, the contractor or the contractor’s authorized representative shall remain on site. The contractor shall further remain accessible during non-working hours, including at night and during days off.

2.3. The geotechnical consultant shall provide observation and testing services and shall make evaluations to advise the client on geotechnical matters. The geotechnical consultant shall report findings and recommendations to the client or the client’s authorized representative.

2.4. Prior to proceeding with any grading operations, the geotechnical consultant shall be notified two working days in advance to schedule the needed observation and testing services.

2.4.1. Prior to any significant expansion or reduction in the grading operation, the geotechnical consultant shall be provided with two working days notice to make appropriate adjustments in scheduling of on-site personnel.



2.4.2. Between phases of grading operations, the geotechnical consultant shall be provided with two working days notice in advance of commencement of ad-ditional grading operations.

3. SITE PREPARATION

Site preparation shall be performed in accordance with the recommendations presented in the

following sections.

3.1. The client, prior to any site preparation or grading, shall arrange and attend a pre-grading meeting between the grading contractor, the design engineer, the geotechnical consultant, and representatives of appropriate governing authorities, as well as any other involved parties. The parties shall be given two working days notice.

3.2. Clearing and grubbing shall consist of the substantial removal of vegetation, brush, grass, wood, stumps, trees, tree roots greater than 1/2-inch in diameter, and other deleterious materials from the areas to be graded. Clearing and grubbing shall extend to the outside of the proposed excavation and fill areas.

3.3. Demolition in the areas to be graded shall include removal of building structures, foundations, reservoirs, utilities (including underground pipelines, septic tanks, leach fields, seepage pits, cisterns, etc.), and other manmade surface and subsurface improvements, and the backfilling of mining shafts, tunnels and surface depressions. Demolition of utilities shall include capping or rerouting of pipelines at the project perimeter, and abandonment of wells in accordance with the requirements of the governing authorities and the recommendations of the geotechnical consultant at the time of demolition.

3.4. The debris generated during clearing, grubbing and/or demolition operations shall be removed from areas to be graded and disposed of off site at a legal dump site. Clearing, grubbing, and demolition operations shall be performed under the observation of the geotechnical consultant.

3.5. The ground surface beneath proposed fill areas shall be stripped of loose or unsuitable soil. These soils may be used as compacted fill provided they are generally free of organic or other deleterious materials and evaluated for use by the geotechnical consultant. The resulting surface shall be evaluated by the geotechnical consultant prior to proceeding. The cleared, natural ground surface shall be scarified to a depth of approximately 8 inches, moisture conditioned, and compacted in accordance with the specifications presented in Section 5 of these guidelines.



4. REMOVALS AND EXCAVATIONS

Removals and excavations shall be performed as recommended in the following sections.

4.1. Removals

4.1.1. Materials which are considered unsuitable shall be excavated under the ob-servation of the geotechnical consultant in accordance with the recommendations contained herein. Unsuitable materials include, but may not be limited to, dry, loose, soft, wet, organic, compressible natural soils, frac-tured, weathered, soft bedrock, and undocumented or otherwise deleterious fill materials.

4.1.2. Materials deemed by the geotechnical consultant to be unsatisfactory due to moisture conditions shall be excavated in accordance with the recommenda-tions of the geotechnical consultant, watered or dried as needed, and mixed to a generally uniform moisture content in accordance with the specifications presented in Section 5 of this document.

4.2. Excavations

4.2.1. Temporary excavations no deeper than 5 feet in firm fill or natural materials may be made with vertical side slopes. To satisfy California Occupational Safety and Health Administration (CAL OSHA) requirements, any excava-tion deeper than 5 feet shall be shored or laid back at a 1:1 inclination or flatter, depending on material type, if construction workers are to enter the excavation.

5. COMPACTED FILL

Fill shall be constructed as specified below or by other methods recommended by the geotechni-

cal consultant. Unless otherwise specified, fill soils shall be compacted to 90 percent relative

compaction, as evaluated in accordance with ASTM Test Method D 1557.

5.1. Prior to placement of compacted fill, the contractor shall request an evaluation of the exposed ground surface by the geotechnical consultant. Unless otherwise recommended, the exposed ground surface shall then be scarified to a depth of approximately 8 inches and watered or dried, as needed, to achieve a generally uniform moisture content at or near the optimum moisture content. The scarified materials shall then be compacted to 90 percent relative compaction. The evaluation of compaction by the geotechnical consultant shall not be considered to preclude any requirements for observation or approval by governing agencies. It is the contractor's responsibility to notify the geotechnical consultant and the appropriate governing



agency when project areas are ready for observation, and to provide reasonable time for that review.

5.2. Excavated on-site materials which are in general compliance with the recommendations of the geotechnical consultant may be utilized as compacted fill provided they are generally free of organic or other deleterious materials and do not contain rock fragments greater than 6 inches in dimension. During grading, the contractor may encounter soil types other than those analyzed during the preliminary geotechnical study. The geotechnical consultant shall be consulted to evaluate the suitability of any such soils for use as compacted fill.

5.3. Where imported materials are to be used on site, the geotechnical consultant shall be notified three working days in advance of importation in order that it may sample and test the materials from the proposed borrow sites. No imported materials shall be delivered for use on site without prior sampling, testing, and evaluation by the geotechnical consultant.

5.4. Soils imported for on-site use shall preferably have very low to low expansion potential (based on UBC Standard 18-2 test procedures). Lots on which expansive soils may be exposed at grade shall be undercut 3 feet or more and capped with very low to low expansion potential fill. Details of the undercutting are provided in the Transition and Undercut Lot Details, Figure B of these guidelines. In the event expansive soils are present near the ground surface, special design and construction considerations shall be utilized in general accordance with the recommendations of the geotechnical consultant.

5.5. Fill materials shall be moisture conditioned to near optimum moisture content prior to placement. The optimum moisture content will vary with material type and other factors. Moisture conditioning of fill soils shall be generally uniform in the soil mass.

5.6. Prior to placement of additional compacted fill material following a delay in the grading operations, the exposed surface of previously compacted fill shall be prepared to receive fill. Preparation may include scarification, moisture conditioning, and recompaction.

5.7. Compacted fill shall be placed in horizontal lifts of approximately 8 inches in loose thickness. Prior to compaction, each lift shall be watered or dried as needed to achieve near optimum moisture condition, mixed, and then compacted by mechanical methods, using sheepsfoot rollers, multiple-wheel pneumatic-tired rollers, or other appropriate compacting rollers, to the specified relative compaction. Successive lifts shall be treated in a like manner until the desired finished grades are achieved.

5.8. Fill shall be tested in the field by the geotechnical consultant for evaluation of general compliance with the recommended relative compaction and moisture conditions. Field density testing shall conform to ASTM D 1556-00 (Sand Cone



method), D 2937-00 (Drive-Cylinder method), and/or D 2922-96 and D 3017-96 (Nuclear Gauge method). Generally, one test shall be provided for approximately every 2 vertical feet of fill placed, or for approximately every 1000 cubic yards of fill placed. In addition, on slope faces one or more tests shall be taken for approximately every 10,000 square feet of slope face and/or approximately every 10 vertical feet of slope height. Actual test intervals may vary as field conditions dictate. Fill found to be out of conformance with the grading recommendations shall be removed, moisture conditioned, and compacted or otherwise handled to accomplish general compliance with the grading recommendations.

5.9. The contractor shall assist the geotechnical consultant by excavating suitable test pits for removal evaluation and/or for testing of compacted fill.

5.10. At the request of the geotechnical consultant, the contractor shall “shut down” or restrict grading equipment from operating in the area being tested to provide adequate testing time and safety for the field technician.

5.11. The geotechnical consultant shall maintain a map with the approximate locations of field density tests. Unless the client provides for surveying of the test locations, the locations shown by the geotechnical consultant will be estimated. The geotechnical consultant shall not be held responsible for the accuracy of the horizontal or vertical locations or elevations.

5.12. Grading operations shall be performed under the observation of the geotechnical consultant. Testing and evaluation by the geotechnical consultant does not preclude the need for approval by or other requirements of the jurisdictional agencies.

5.13. Fill materials shall not be placed, spread or compacted during unfavorable weather conditions. When work is interrupted by heavy rains, the filling operation shall not be resumed until tests indicate that moisture content and density of the fill meet the project specifications. Regrading of the near-surface soil may be needed to achieve the specified moisture content and density.

5.14. Upon completion of grading and termination of observation by the geotechnical consultant, no further filling or excavating, including that planned for footings, foundations, retaining walls or other features, shall be performed without the involvement of the geotechnical consultant.

5.15. Fill placed in areas not previously viewed and evaluated by the geotechnical consultant may have to be removed and recompacted at the contractor's expense. The depth and extent of removal of the unobserved and undocumented fill will be decided based upon review of the field conditions by the geotechnical consultant.



5.16. Off-site fill shall be treated in the same manner as recommended in these specifications for on-site fills. Off-site fill subdrains temporarily terminated (up gradient) shall be surveyed for future locating and connection.

6. OVERSIZED MATERIAL

Oversized material shall be placed in accordance with the following recommendations.

6.1. During the course of grading operations, rocks or similar irreducible materials greater than 6 inches in dimension (oversized material) may be generated. These materials shall not be placed within the compacted fill unless placed in general accordance with the recommendations of the geotechnical consultant.

6.2. Where oversized rock (greater than 6 inches in dimension) or similar irreducible material is generated during grading, it is recommended, where practical, to waste such material off site, or on site in areas designated as “nonstructural rock disposal areas.” Rock designated for disposal areas shall be placed with sufficient sandy soil to generally fill voids. The disposal area shall be capped with a 5-foot thickness of fill which is generally free of oversized material.

6.3. Rocks 6 inches in dimension and smaller may be utilized within the compacted fill, provided they are placed in such a manner that nesting of rock is not permitted. Fill shall be placed and compacted over and around the rock. The amount of rock greater than 3/4-inch in dimension shall generally not exceed 40 percent of the total dry weight of the fill mass, unless the fill is specially designed and constructed as a “rock fill.”

6.4. Rocks or similar irreducible materials greater than 6 inches but less than 4 feet in dimension generated during grading may be placed in windrows and capped with finer materials in accordance with the recommendations of the geotechnical consultant, the approval of the governing agencies, and the Oversized Rock Placement Detail, Figure D, of these guidelines. Selected native or imported granular soil (Sand Equivalent of 30 or higher) shall be placed and flooded over and around the windrowed rock such that voids are filled. Windrows of oversized materials shall be staggered so that successive windrows of oversized materials are not in the same vertical plane. Rocks greater than 4 feet in dimension shall be broken down to 4 feet or smaller before placement, or they shall be disposed of off site.



7. SLOPES

The following sections provide recommendations for cut and fill slopes.

7.1. Cut Slopes

7.1.1. The geotechnical consultant shall observe cut slopes during excavation. The geotechnical consultant shall be notified by the contractor prior to beginning slope excavations.

7.1.2. If, during the course of grading, adverse or potentially adverse geotechnical conditions are encountered in the slope which were not anticipated in the pre-liminary evaluation report, the geotechnical consultant shall evaluate the conditions and provide appropriate recommendations.

7.2. Fill Slopes

7.2.1. When placing fill on slopes steeper than 5:1 (horizontal:vertical), topsoil, slope wash, colluvium, and other materials deemed unsuitable shall be re-moved. Near-horizontal keys and near-vertical benches shall be excavated into sound bedrock or firm fill material, in accordance with the recommenda-tion of the geotechnical consultant. Keying and benching shall be accomplished. Compacted fill shall not be placed in an area subsequent to keying and benching until the area has been observed by the geotechnical consultant. Where the natural gradient of a slope is less than 5:1, benching is generally not recommended. However, fill shall not be placed on compressi-ble or otherwise unsuitable materials left on the slope face.

7.2.2. Within a single fill area where grading procedures dictate two or more sepa-rate fills, temporary slopes (false slopes) may be created. When placing fill adjacent to a temporary slope, benching shall be conducted in the manner de-scribed in Section 7.2.1. A 3-foot or higher near-vertical bench shall be excavated into the documented fill prior to placement of additional fill.

7.2.3. Unless otherwise recommended by the geotechnical consultant and accepted by the Building Official, permanent fill slopes shall not be steeper than 2:1 (horizontal:vertical). The height of a fill slope shall be evaluated by the geo-technical consultant.

7.2.4. Unless specifically recommended otherwise, compacted fill slopes shall be overbuilt and cut back to grade, exposing firm compacted fill. The actual amount of overbuilding may vary as field conditions dictate. If the desired re-sults are not achieved, the existing slopes shall be overexcavated and reconstructed in accordance with the recommendations of the geotechnical consultant. The degree of overbuilding may be increased until the desired



compacted slope face condition is achieved. Care shall be taken by the con-tractor to provide mechanical compaction as close to the outer edge of the overbuilt slope surface as practical.

7.2.5. If access restrictions, property line location, or other constraints limit over-building and cutting back of the slope face, an alternative method for compaction of the slope face may be attempted by conventional construc-tion procedures including backrolling at intervals of 4 feet or less in vertical slope height, or as dictated by the capability of the available equipment, whichever is less. Fill slopes shall be backrolled utilizing a conventional sheeps foot-type roller. Care shall be taken to maintain the specified mois-ture conditions and/or reestablish the same, as needed, prior to backrolling.

7.2.6. The placement, moisture conditioning and compaction of fill slope materials shall be done in accordance with the recommendations presented in Section 5 of these guidelines.

7.2.7. The contractor shall be ultimately responsible for placing and compacting the soil out to the slope face to obtain a relative compaction of 90 percent as evaluated by ASTM D 1557 and a moisture content in accordance with Section 5. The geotechnical consultant shall perform field moisture and density tests at intervals of one test for approximately every 10,000 square feet of slope.

7.2.8. Backdrains shall be provided in fill as recommended by the geotechnical consultant.

7.3. Top-of-Slope Drainage

7.3.1. For pad areas above slopes, positive drainage shall be established away from the top of slope. This may be accomplished utilizing a berm and pad gradient of 2 percent or steeper at the top-of-slope areas. Site runoff shall not be per-mitted to flow over the tops of slopes.

7.3.2. Gunite-lined brow ditches shall be placed at the top of cut slopes to redirect surface runoff away from the slope face where drainage devices are not oth-erwise provided.

7.4. Slope Maintenance

7.4.1. In order to enhance surficial slope stability, slope planting shall be accom-plished at the completion of grading. Slope plants shall consist of deep-rooting, variable root depth, drought-tolerant vegetation. Native vegetation is generally desirable. Plants native to semiarid and arid areas may also be ap-propriate. Large-leafed ice plant should not be used on slopes. A landscape



architect shall be consulted regarding the actual types of plants and planting configuration to be used.

7.4.2. Irrigation pipes shall be anchored to slope faces and not placed in trenches excavated into slope faces. Slope irrigation shall be maintained at a level just sufficient to support plant growth. Property owners shall be made aware that over watering of slopes is detrimental to slope stability. Slopes shall be moni-tored regularly and broken sprinkler heads and/or pipes shall be repaired immediately.

7.4.3. Periodic observation of landscaped slope areas shall be planned and appropri-ate measures taken to enhance growth of landscape plants.

7.4.4. Graded swales at the top of slopes and terrace drains shall be installed and the property owners notified that the drains shall be periodically checked so that they may be kept clear. Damage to drainage improvements shall be repaired immediately. To reduce siltation, terrace drains shall be constructed at a gra-dient of 3 percent or steeper, in accordance with the recommendations of the project civil engineer.

7.4.5. If slope failures occur, the geotechnical consultant shall be contacted immedi-ately for field review of site conditions and development of recommendations for evaluation and repair.

8. TRENCH BACKFILL

The following sections provide recommendations for backfilling of trenches.

8.1. Trench backfill shall consist of granular soils (bedding) extending from the trench bottom to 1 foot or more above the pipe. On-site or imported fill which has been evaluated by the geotechnical consultant may be used above the granular backfill. The cover soils directly in contact with the pipe shall be classified as having a very low expansion potential, in accordance with UBC Standard 18-2, and shall contain no rocks or chunks of hard soil larger than 3/4-inch in diameter.

8.2. Trench backfill shall, unless otherwise recommended, be compacted by mechanical means to 90 percent relative compaction as evaluated by ASTM D 1557. Backfill soils shall be placed in loose lifts 8-inches thick or thinner, moisture conditioned, and compacted in accordance with the recommendations of Section 5. of these guidelines. The backfill shall be tested by the geotechnical consultant at vertical intervals of approximately 2 feet of backfill placed and at spacings along the trench of approximately 100 feet in the same lift.



8.3. Jetting of trench backfill materials is generally not a recommended method of densification, unless the on-site soils are sufficiently free-draining and provisions have been made for adequate dissipation of the water utilized in the jetting process.

8.4. If it is decided that jetting may be utilized, granular material with a sand equivalent greater than 30 shall be used for backfilling in the areas to be jetted. Jetting shall generally be considered for trenches 2 feet or narrower in width and 4 feet or shallower in depth. Following jetting operations, trench backfill shall be mechanically compacted to the specified compaction to finish grade.

8.5. Trench backfill which underlies the zone of influence of foundations shall be mechanically compacted to 90 percent or greater relative compaction, as evaluated by ASTM D 1557-02. The zone of influence of the foundations is generally defined as the roughly triangular area within the limits of a 1:1 (horizontal:vertical) projection from the inner and outer edges of the foundation, projected down and out from both edges.

8.6. Trench backfill within slab areas shall be compacted by mechanical means to a relative compaction of 90 percent, as evaluated by ASTM D 1557. For minor interior trenches, density testing may be omitted or spot testing may be performed, as deemed appropriate by the geotechnical consultant.

8.7. When compacting soil in close proximity to utilities, care shall be taken by the grading contractor so that mechanical methods used to compact the soils do not damage the utilities. If the utility contractors indicate that it is undesirable to use compaction equipment in close proximity to a buried conduit, then the grading contractor may elect to use light mechanical compaction equipment or, with the approval of the geotechnical consultant, cover the conduit with clean granular material. These granular materials shall be jetted in place to the top of the conduit in accordance with the recommendations of Section 8.4 prior to initiating mechanical compaction procedures. Other methods of utility trench compaction may also be appropriate, upon review by the geotechnical consultant and the utility contractor, at the time of construction.

8.8. Clean granular backfill and/or bedding materials are not recommended for use in slope areas unless provisions are made for a drainage system to mitigate the potential for buildup of seepage forces or piping of backfill materials.

8.9. The contractor shall exercise the specified safety precautions, in accordance with OSHA Trench Safety Regulations, while conducting trenching operations. Such precautions include shoring or laying back trench excavations at 1:1 or flatter, depending on material type, for trenches in excess of 5 feet in depth. The geotechnical consultant is not responsible for the safety of trench operations or stability of the trenches.



9. DRAINAGE

The following sections provide recommendations pertaining to site drainage.

9.1. Roof, pad, and slope drainage shall be such that it is away from slopes and structures to suitable discharge areas by nonerodible devices (e.g., gutters, downspouts, concrete swales, etc.).

9.2. Positive drainage adjacent to structures shall be established and maintained. Positive drainage may be accomplished by providing drainage away from the foundations of the structure at a gradient of 2 percent or steeper for a distance of 5 feet or more outside the building perimeter, further maintained by a graded swale leading to an appropriate outlet, in accordance with the recommendations of the project civil engineer and/or landscape architect.

9.3. Surface drainage on the site shall be provided so that water is not permitted to pond. A gradient of 2 percent or steeper shall be maintained over the pad area and drainage patterns shall be established to remove water from the site to an appropriate outlet.

9.4. Care shall be taken by the contractor during grading to preserve any berms, drainage terraces, interceptor swales or other drainage devices of a permanent nature on or adjacent to the property. Drainage patterns established at the time of finish grading shall be maintained for the life of the project. Property owners shall be made very clearly aware that altering drainage patterns may be detrimental to slope stability and foundation performance.

10. SITE PROTECTION

The site shall be protected as outlined in the following sections.

10.1. Protection of the site during the period of grading shall be the responsibility of the contractor unless other provisions are made in writing and agreed upon among the concerned parties. Completion of a portion of the project shall not be considered to preclude that portion or adjacent areas from the need for site protection, until such time as the project is finished as agreed upon by the geotechnical consultant, the client, and the regulatory agency.

10.2. The contractor is responsible for the stability of temporary excavations. Recommendations by the geotechnical consultant pertaining to temporary excavations are made in consideration of stability of the finished project and, therefore, shall not be considered to preclude the responsibilities of the contractor. Recommendations by the geotechnical consultant shall also not be considered to preclude more restrictive requirements by the applicable regulatory agencies.



10.3. Precautions shall be taken during the performance of site clearing, excavation, and grading to protect the site from flooding, ponding, or inundation by surface runoff. Temporary provisions shall be made during the rainy season so that surface runoff is away from and off the working site. Where low areas cannot be avoided, pumps shall be provided to remove water as needed during periods of rainfall.

10.4. During periods of rainfall, plastic sheeting shall be used as needed to reduce the potential for unprotected slopes to become saturated. Where needed, the contractor shall install check dams, desilting basins, riprap, sandbags or other appropriate devices or methods to reduce erosion and provide recommended conditions during inclement weather.

10.5. During periods of rainfall, the geotechnical consultant shall be kept informed by the contractor of the nature of remedial or precautionary work being performed on site (e.g., pumping, placement of sandbags or plastic sheeting, other labor, dozing, etc.).

10.6. Following periods of rainfall, the contractor shall contact the geotechnical consultant and arrange a walk-over of the site in order to visually assess rain-related damage. The geotechnical consultant may also recommend excavation and testing in order to aid in the evaluation. At the request of the geotechnical consultant, the contractor shall make excavations in order to aid in evaluation of the extent of rain-related damage.

10.7. Rain- or irrigation-related damage shall be considered to include, but may not be limited to, erosion, silting, saturation, swelling, structural distress, and other adverse conditions noted by the geotechnical consultant. Soil adversely affected shall be classified as “Unsuitable Material” and shall be subject to overexcavation and replacement with compacted fill or to other remedial grading as recommended by the geotechnical consultant.

10.8. Relatively level areas where saturated soils and/or erosion gullies exist to depths greater than 1 foot shall be overexcavated to competent materials as evaluated by the geotechnical consultant. Where adverse conditions extend to less than 1 foot in depth, saturated and/or eroded materials may be processed in-place. Overexcavated or in-place processed materials shall be moisture conditioned and compacted in accordance with the recommendations provided in Section 5. If the desired results are not achieved, the affected materials shall be overexcavated, moisture conditioned, and compacted until the specifications are met.

10.9. Slope areas where saturated soil and/or erosion gullies exist to depths greater than 1 foot shall be overexcavated and replaced as compacted fill in accordance with the applicable specifications. Where adversely affected materials exist to depths of 1 foot or less below proposed finished grade, remedial grading by moisture conditioning in-place and compaction in accordance with the appropriate specifications may be attempted. If the desired results are not achieved, the affected materials shall be



overexcavated, moisture conditioned, and compacted until the specifications are met. As conditions dictate, other slope repair procedures may also be recommended by the geotechnical consultant.

10.10. During construction, the contractor shall grade the site to provide positive drainage away from structures and to keep water from ponding adjacent to structures. Water shall not be allowed to damage adjacent properties. Positive drainage shall be maintained by the contractor until permanent drainage and erosion reducing devices are installed in accordance with project plans.



11. DEFINITIONS OF TERMS

ALLUVIUM: Unconsolidated detrital deposits deposited by flowing water; includes sediments deposited in river beds, canyons, flood plains, lakes, fans at the foot of slopes, and in estuaries.

AS-GRADED (AS-BUILT): The site conditions upon completion of grading.

BACKCUT: A temporary construction slope at the rear of earth-retaining structures such as buttresses, shear keys, stabilization fills, or retaining walls.

BACKDRAIN: Generally a pipe-and-gravel or similar drainage system placed behind earth-retaining structures such as buttresses, stabilization fills, and retaining walls.

BEDROCK: Relatively undisturbed in-place rock, either at the surface or beneath surficial deposits of soil.

BENCH: A relatively level step and near-vertical riser excavated into sloping ground on which fill is to be placed.

BORROW (IMPORT): Any fill material hauled to the project site from off-site areas.

BUTTRESS FILL: A fill mass, the configuration of which is designed by engi-neering calculations, to retain slopes containing adverse geologic features. A buttress is generally specified by a key width and depth and by a backcut angle. A buttress normally contains a back drainage system.

CIVIL ENGINEER: The Registered Civil Engineer or consulting firm responsible for preparation of the grading plans and surveying, and evaluating as-graded topographic conditions.

CLIENT: The developer or a project-responsible authorized represen-tative. The client has the responsibility of reviewing the findings and recommendations made by the geotechnical consultant and authorizing the contractor and/or other con-sultants to perform work and/or provide services.

COLLUVIUM: Generally loose deposits, usually found on the face or near the base of slopes and brought there chiefly by gravity through slow continuous downhill creep (see also Slope Wash).

COMPACTION: The densification of a fill by mechanical means.



CONTRACTOR: A person or company under contract or otherwise retained by the client to perform demolition, grading, and other site improvements.

DEBRIS: The products of clearing, grubbing, and/or demolition, or contaminated soil material unsuitable for reuse as compacted fill, and/or any other material so designated by the geotech-nical consultant.

ENGINEERED FILL: A fill which the geotechnical consultant or the consultant’s representative has observed and/or tested during placement, enabling the consultant to conclude that the fill has been placed in substantial compliance with the recommendations of the geotechnical consultant and the governing agency re-quirements.

ENGINEERING GEOLOGIST: A geologist registered by the state licensing agency who ap-plies geologic knowledge and principles to the exploration and evaluation of naturally occurring rock and soil, as re-lated to the design of civil works.

EROSION: The wearing away of the ground surface as a result of the movement of wind, water, and/or ice.

EXCAVATION: The mechanical removal of earth materials.

EXISTING GRADE: The ground surface configuration prior to grading; original grade.

FILL: Any deposit of soil, rock, soil-rock blends, or other similar materials placed by man.

FINISH GRADE: The as-graded ground surface elevation that conforms to the grading plan.

GEOFABRIC: An engineering textile utilized in geotechnical applications such as subgrade stabilization and filtering.

GEOTECHNICAL CONSULTANT: The geotechnical engineering and engineering geology con-sulting firm retained to provide technical services for the project. For the purpose of these specifications, observations by the geotechnical consultant include observations by the geotechnical engineer, engineering geologist and other per-sons employed by and responsible to the geotechnical consultant.



GEOTECHNICAL ENGINEER: A licensed civil engineer and geotechnical engineer, regis-tered by the state licensing agency, who applies scientific methods, engineering principles, and professional experience to the acquisition, interpretation, and use of knowledge of materials of the earth's crust to the resolution of engineering problems. Geotechnical engineering encompasses many of the engineering aspects of soil mechanics, rock mechanics, geology, geophysics, hydrology, and related sciences.

GRADING: Any operation consisting of excavation, filling, or combina-tions thereof and associated operations.

LANDSLIDE DEPOSITS: Material, often porous and of low density, produced from instability of natural or manmade slopes.

OPTIMUM MOISTURE: The moisture content that is considered optimum relative to correction operations obtained from ASTM test method D 1557.

RELATIVE COMPACTION: The degree of compaction (expressed as a percentage) of a material as compared to the dry density obtained from ASTM test method D 1557.

ROUGH GRADE: The ground surface configuration at which time the surface elevations approximately conform to the project plan.

SHEAR KEY: Similar to a subsurface buttress; however, it is generally con-structed by excavating a slot within a natural slope in order to stabilize the upper portion of the slope without encroach-ing into the lower portion of the slope.

SITE: The particular parcel of land where grading is being per-formed.

SLOPE: An inclined ground surface, the steepness of which is gener-ally specified as a ratio of horizontal units to vertical units.

SLOPE WASH: Soil and/or rock material that has been transported down a slope by gravity assisted by the action of water not confined to channels (see also Colluvium).

SLOUGH: Loose, uncompacted fill material generated during grading operations.



SOIL: Naturally occurring deposits of sand, silt, clay, etc., or com-binations thereof.

STABILIZATION FILL: A fill mass, the configuration of which is typically related to slope height and is specified by the standards of practice for enhancing the stability of locally adverse conditions. A stabi-lization fill is normally specified by a key width and depth and by a backcut angle. A stabilization fill may or may not have a back drainage system specified.

SUBDRAIN: Generally a pipe-and-gravel or similar drainage system placed beneath a fill along the alignment of buried canyons or former drainage channels.

TAILINGS: Non-engineered fill which accumulates on or adjacent to equipment haul roads.

TERRACE: A relatively level bench constructed on the face of a graded slope surface for drainage and maintenance purposes.

TOPSOIL: The upper zone of soil or bedrock materials, which is usually dark in color, loose, and contains organic materials.

WINDROW: A row of large rocks buried within engineered fill in accor-dance with guidelines set forth by the geotechnical consultant.


TYPICAL EARTHWORK GUIDELINES.doc Rev. 12/05

geologic hazards assessment and · pdf fileto review the construction plans before they go to...

Documents