Appendix Geotechnical Investigation for Proposed Lost ... · PRELIMINARY GEOTECHNICAL INVESTIGATION FOR PROPOSED SOLAR PLANT, LOST HILLS, KERN COUNTY, ... Soil resistivity is calculated

Appendix F Preliminary Geotechnical Investigation for Proposed

Solar Plant, Lost Hills, Kern County, California

F I N A L R E P O R T

PRELIMINARY GEOTECHNICALINVESTIGATION FOR PROPOSEDSOLAR PLANT, LOST HILLS,KERN COUNTY, CALIFORNIA

Prepared For

NextLight Renewable Power, LLC353 Sacramento Street, Suite 2100San Francisco, CA 94111

January 26, 2010Project No. 29871499

URS Corporation2020 East First Street, Suite 400Santa Ana, California 92705-4032

Preliminary Geotechnical Investigation, NextLight Lost Hills

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TABLE OF CONTENTS

SECTION PAGE

ACRONYMS AND ABBREVIATIONS................................................................................................. III

EXECUTIVE SUMMARY ........................................................................................................... ES-1

1.0 AUTHORIZATION AND PROJECT DESCRIPTION ................................................................ 1-1

2.0 FIELD EXPLORATION AND LABORATORY TESTING .......................................................... 2-1

2.1 Borings ............................................................................................................ 2-1

2.2 Electrical Resistivity Testing............................................................................ 2-1

2.3 Laboratory Testing........................................................................................... 2-2

3.0 SITE SURFACE AND GEOLOGIC CONDITIONS .................................................................. 3-1

3.1 Regional Geologic Conditions.......................................................................... 3-1

3.2 Local Geologic Setting..................................................................................... 3-1

3.3 Surface Conditions........................................................................................... 3-2

3.4 Subsurface Soil Conditions .............................................................................. 3-2

3.5 Groundwater Conditions .................................................................................. 3-3

3.6 Geologic Hazards............................................................................................. 3-3

3.6.1 General ...........................................................................................................3-33.6.2 Landslides ......................................................................................................3-33.6.3 Flooding and Erosion ......................................................................................3-33.6.4 Subsidence......................................................................................................3-43.6.5 Poor Soil Conditions (Expansive, Collapsible, or Corrosive Soils)...................3-43.6.6 Primary Ground Rupture.................................................................................3-53.6.7 Strong Ground Motion ....................................................................................3-53.6.8 Liquefaction....................................................................................................3-53.6.9 Seismically Induced Settlement.......................................................................3-6

4.0 CONCLUSIONS AND RECOMMENDATIONS ........................................................................ 4-1

4.1 General ............................................................................................................ 4-1

4.2 Shallow Foundations........................................................................................ 4-1

4.3 Deep Foundation for PV Support Structure ...................................................... 4-3

4.4 Earthwork ........................................................................................................ 4-3

4.4.1 General Grading Requirements .......................................................................4-34.4.2 Demolition......................................................................................................4-44.4.3 Site Preparation and Removals ........................................................................4-44.4.4 Site Dewatering and Control of Water .............................................................4-54.4.5 Fill Materials ..................................................................................................4-54.4.6 Trenches .........................................................................................................4-64.4.7 Fill Placement and Compaction.......................................................................4-6

4.5 Temporary Excavations.................................................................................... 4-7


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4.6 Anticipated Excavation Conditions .................................................................. 4-8

4.7 Recommendations for Future Geotechnical Investigation ................................. 4-8

5.0 LIMITATIONS ................................................................................................................. 5-1

6.0 REFERENCES................................................................................................................ 6-1

Figures

1 Site Location and Regional Geologic Map2 Site Plan and Approximate Exploration Locations

Appendices

A BoringsB Electrical Resistivity Testing DataC Laboratory Testing


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ACRONY MS AND AB BRE V IAT I ONS

bgs below the ground surface

BV Black and Veatch

CGS California Geological Survey

CDMG California Division of Mines and Geology

FEMA Federal Emergency Management Agency

lbs/in2 pounds per square inch

lbs/ft2 pounds per square foot

lbs/ft3 pounds per cubic foot

mm millimeter

MSL above mean sea-level

NextLight NextLight Renewable Power, LLC

PV photovoltaic

RFP request for proposal

SAFZ San Andreas fault zone

URS URS Corporation

USGS United States Geological Survey


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EX E CUTIV E SU MMA RY

This report summarizes the geotechnical investigation performed by URS Corporation (URS) for the

proposed solar plant that NextLight Renewable Power, LLC (NextLight) is considering constructing near

Lost Hills, California. The project site is basically an open rectangular field measuring approximately

one-half mile by one mile.

Three borings were advanced at spacings of approximately one-half mile. Surficial geologic materials

consist of Holocene-age alluvial fan deposits. The material encountered in the upper five feet includes

very stiff fat clay (CH), stiff lean clay (CL), and loose to medium dense clayey sand (SC) and silty sand

(SM). The deeper soils, from 5 to 26.5 feet below ground surface, also encompass a range of soils,

including interbedded medium dense clayey sand (SC) and stiff to very stiff lean clay (CL); interbedded

loose clayey sand (SC) and silty sand (SM); and stiff to very stiff fat clay (CH). Dense, poorly graded

sand with silt (SP-SM) was encountered in the lower part of boring BV-3. Groundwater was not

encountered during our subsurface investigation to the maximum depth explored (26.5 feet) and is

anticipated to be greater than 50 feet below ground surface.

Geologic and seismic hazards that might affect the site were reviewed using published reports and data.

Our assessment suggests that there is little to no potential for landslides, subsidence, fault surface rupture,

liquefaction, and seismic settlement, and some potential for flooding and erosion, poor soil conditions,

and strong ground shaking. With appropriate mitigation, all identified geologic and seismic hazards are

considered less than significant. To the extent of the information available for this investigation, geologic

and seismic hazards do not appear to represent a “fatal flaw” for the proposed development.

Based on the results of URS’ geotechnical investigation, the site appears suitable, from a geotechnical

standpoint and at a feasibility level, for the proposed development of a solar plant. Consistent with usual

NextLight practice, shallow spread footings may be used to support the transformers and pre-engineered

O&M Building; the PV panel support structures may be supported on either shallow or deep foundations.

Some issues remain to be investigated with respect to founding the PV panel supports on spread footings

bearing on the ground surface. These include the effects of agricultural plowing on the near surface soil;

the extent and characteristics of expansive clays that may be found near ground surface in part of the site;

the effects of erosion, which could undermine footings having no embedment; and the depth and effects

of frost penetration. Recommendations are also provided for site earthwork, including electrical trenches,

and for future, more detailed geotechnical investigation for the project.


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1.0 AUTHO RI ZAT I ON AN D PR OJ E C T DE S CRIP T I ON

This report summarizes the geotechnical investigation performed by URS Corporation (URS) for the

proposed solar plant that NextLight Renewable Power, LLC (NextLight) is considering building near

Lost Hills, California. Figure 1, Site Location Map, shows the site location. URS’ geotechnical services

were authorized under URS’ Master Services Agreement with NextLight by NextLight Order No. 51

dated December 7, 2009. The scope of services is described in the request for proposal (RFP) issued by

NextLight’s engineer, Black and Veatch (BV), and URS’ proposal dated November 23, 2009.

The project consists of a proposed solar plant, including photovoltaic (PV) panels, transformers and a pre-

engineered O&M Building. Only limited information was available at this feasibility stage of the project.

No information was provided concerning the layout of facilities or site grading, if any. The following

preliminary table of loads and settlement criteria for project features was provided for this investigation.

Maximum Settlement (inches)Structure/FoundationType

Approx. Dead Load(average lbs/ft

2)

Approx. Footing Size

(ft) Total Differential

Transformer Pad(s) -Large

2,500 15 x 15 1.5 0.5

Transformer Pad(s)– Small

Up to 1,000 5 x 5 1.5 0.5

O&M Building (Pre-Engineered)

2,5005 x 5 (at columnswith grade beamor thickened slab)

1.5 0.5

PV Panel Support 1,000 2 x 8 1.5 0.5

PV SupportStructure (steel pipe

or concrete pier)

Vertical Load of500 to 4000 lbs

Unknown 1.0 N/A


or concrete pier)

Lateral Load of2,000 to 6,000 lbs

Unknown 1.0 N/A


or concrete pier)

Moment of 15 to50 kip-ft

Unknown 1.0 N/A



2.0 F IE LD EX P L ORATI ON AND LAB ORATORY TE S T IN G

URS performed borings and electrical resistivity tests, as well as laboratory tests for the subject project, as

described in 02211 – Subsurface Investigation provided by BV.

2.1 BORINGS

URS advanced three 26.5-foot deep test borings at the site using a Central Mine Equipment Company

(CME) 55 drill rig and hollow-stem augers. Figure 2 shows the approximate locations of the borings,

designated BV-1, -2 and -3; the latitudes and longitudes of the borings are indicated on the borings logs.

The borings were advanced following ASTM D 1452, “Standard Practice for Soil Exploration and

Sampling by Auger Borings”. Soil samples and blow count data were obtained for each boring. The

samples were taken with Standard Penetration Test (SPT) 2-inch split barrel sampler and a 3-inch

diameter thin-wall tube sampler. Appendix A presents additional details concerning the boring program,

the boring logs, and a key to the boring logs. URS’ field engineer transported the samples to URS’

geotechnical laboratory in Santa Ana for review and testing.

2.2 ELECTRICAL RESISTIVITY TESTING

URS performed electrical resistivity testing along two perpendicular traverses (ER-1 and ER-2) in the

vicinity of boring BV-2 on December 17 and 18, 2009. Figure 2 shows the approximate location of boring

BV-2.

The tests were performed with a SuperSting R1/IP, DC-Memory Earth Resistivity Meter manufactured by

Advanced Geosciences, Inc. following ASTM G 57, “Standard Test Method for Field Measurement of

Soil Resistivity Using the Wenner Four-Electrode Method” and IEEE 81, “IEEE Guide for Measuring

Earth Resistivity, Ground Impedance, and Earth Surface Potentials of a Ground System”.

The four electrodes were placed in a straight line along the traverse with equal spacing between them, and

driven into the soil. The electrode "a" spacings on both traverses were: 3, 6, 10, 12, 16, 20, 25, 30 and 60

feet. A summary of the test results is presented in the following table. Appendix B presents the electrical

resistivity test data.



Traverse ER-1 Traverse ER-2

ElectrodeSpacing, a

(ft)

MeasuredResistance,

R(ohms)

Soil Resistivity(ohm-cm)

MeasuredResistance,

R(ohms)

Soil Resistivity(ohm-cm)

3 10.07 5786 8.55 4915

6 3.8 4364 2.37 2724

10 2.27 4351 1.59 3035

12 1.63 3748 1.41 3245

16 1.231 3772 1.037 3178

20 0.7931 3038 0.8143 3119

25 0.4413 2113 0.5402 2586

30 0.5762 3310 0.3942 2265

60 0.1975 2269 0.2152 2473

Average 3639 3133

Notes:

1. Soil resistivity is calculated per ASTM G57 by the following formula:

Soil Resistivity = 2πaR (using consistent units)

2. Probe embedment was 3 inches.

2.3 LABORATORY TESTING

Laboratory testing was performed on selected samples authorized by BV. The tests consisted of in situ

water content; liquid limit, plastic limit and plasticity index; and particle-size distribution. Appendix C

provides the test procedures used and presents a summary of the results.



3.0 S ITE SURFACE AN D GE OL O GI C C ON DIT I ONS

3.1 REGIONAL GEOLOGIC CONDITIONS

The project site is located in the southwestern portion of the Great Valley geomorphic province of

California. The Great Valley, also known as the Central Valley is an elongate, northwest trending, nearly

flat lowland that is located between the Sierra Nevada Mountains on the east and the Coast Ranges on the

west. The Sacramento River drains the northern portion of the Great Valley and the San Joaquin River

drains the southern portion of the valley. The southern part of the Great Valley, where the project site is

located, is also known as the San Joaquin Valley.

The Great Valley consists of the alluvial flood and delta plains of the Sacramento River, the San Joaquin

River and their tributaries. The region has persisted as a shallow marine embayment and later as a

lowland for the entire Cenozoic and the latest Mesozoic eras (from about 100 million years ago to

present). The valley originated below sea level as an offshore area that was later enclosed by uplift of the

Coast Ranges. Over the millennia the valley was filled by the sediments eroded from the Coast Ranges

and the Sierra Nevada Mountains. In the late Cenozoic much of the Great Valley was occupied by

shallow brackish and freshwater lakes (Norris and Webb, 1990).

The project site is in a seismically active region that will be subjected to future seismic shaking during

earthquakes generated by any of several surrounding active faults. The San Andreas fault is located

approximately 14 miles southwest of the site. It is a right-lateral, strike-slip fault that extends over 700

miles (1,120 km) from the Gulf of California to Cape Mendocino in northern California. Several historic

earthquakes on the San Andreas fault zone (SAFZ) have produced significant seismic shaking at the

project site. The most notable example is the January 9, 1857 Fort Tejon earthquake, one of the greatest

earthquakes ever recorded in the United States. The Fort Tejon earthquake produced a surface rupture of

over 217 miles (350 kilometers) in length along the San Andreas fault zone from Cholame on the north to

the Cajon Pass area on the south. The epicenter of the Fort Tejon earthquake was located approximately

22 miles (35 kilometers) south of the site. This earthquake, which was estimated to be near magnitude 8,

produced an average slip of 15 feet and a maximum slip of 30 feet in the Carrizo Plain area. Strong

shaking caused by the earthquake was reported to have lasted at least one minute.

3.2 LOCAL GEOLOGIC SETTING

The project site is located within the Antelope Plain at elevations ranging between approximately 580 to

620 feet above mean sea level (National Geodetic Vertical Datum of 1929 datum). The Antelope Plain is

a nearly flat, shallow, northeast sloping surface formed from alluvial fan deposits derived from the

Temblor Range, which is located towards the southwest.

In the vicinity of the project site, the generally flat Antelope Plain is slightly interrupted by the Lost Hills

and the Antelope Hills. The Lost Hills and Antelope Hills are the surface expression of northwest-

trending anticlinal folds that form oil traps along the west side of the San Joaquin Valley. The Lost Hill

Oil Field, discovered in 1910 (California Division of Mines, 1943), is located about 5 miles to the



northeast of the project site and the Belridge Oil Field, discovered in 1911 (California Division of Mines,

1943) in the Antelope Hills, is located about 3 miles to the southeast.

Based on a review of regional geologic maps of the area (USGS, 1921; CDMG, 1964), surficial geologic

materials on site consist of Holocene-age alluvial fan deposits that are typically comprised of fine sandy

soil (see Figure 1). These conditions were generally confirmed during URS’s site subsurface investigation

which included the advancement and logging of three hollow stem auger soil borings to a maximum depth

of 26.5 feet. As shown on the borings logs presented in Appendix A, soil encountered during the our

subsurface investigation generally consisted of interlayered silty sand, clay, clayey sand, and sandy clay

that was typically dry to moist and medium dense (stiff) in place. Near surface soils within the upper 6-

to 12-inches were noted to be relatively loose and disturbed from past plowing and agricultural

operations.

Soil Survey maps for the project site (USDA Soil Conservation Service, 1988) indicate that near surface

soils generally consist of fine sandy, silty, and clayey loams.

3.3 SURFACE CONDITIONS

The project site is located on the north side of Paso Robles Highway (Highway 46), with the southwest

corner being about one-half mile east of the intersection of Highway 46 and West Side Highway

(Highway 33). The project site is basically an open rectangular field measuring approximately one-half

mile by one mile. At the time of the field work in December 2009, the field was barren and had been

plowed, so the surface was quite uneven.

On the south side of the project site, approximately at one-quarter mile west of the southeast corner of the

site, adjacent to Highway 46, there is an electrical substation regulating power supply in the area. Within

the site itself, approximately one-half mile north of the southwest corner of the site, there is an abandoned

building, which resembled a workshop supported by steel pillars and steel roof and had no walls. It

appeared like the workshop was drawing its power supply from the adjacent overhead line running across

the site. Also, four irrigation lines run east-west across the site at regular intervals from north to south.

Concrete manhole covers extend at least a foot above the ground at regular intervals along the irrigation

lines.

3.4 SUBSURFACE SOIL CONDITIONS

Based on the subsurface investigations at the site (see boring logs in Appendix A), the site subsurface

varies at the three borings, which are spaced with approximately one-half mile between the closest

boreholes. The material encountered in the upper five feet includes very stiff fat clay (CH), stiff lean clay

(CL), and loose to medium dense clayey sand (SC) and silty sand (SM). The deeper soils, from 5 to 26.5

feet below ground surface, also encompass a range of soils, including interbedded medium dense clayey

sand (SC) and stiff to very stiff lean clay (CL), interbedded loose clayey sand (SC) and silty sand (SM),

stiff to very stiff fat clay (CH). Dense, poorly graded sand with silt (SP-SM) was encountered in the lower

part of boring BV-3.



The soil samples generally reacted strongly when exposed to dilute hydrochloric acid, indicating the

presence of carbonate cementation. A thin layer of hardpan was encountered in boring BV-1 at about 22

feet below ground surface.

3.5 GROUNDWATER CONDITIONS

Based on our review of available published and unpublished literature, useful historic groundwater data

are not available for the project site and immediate vicinity. Groundwater was not encountered during our

subsurface investigation to the maximum depth explored (26.5 feet) and is anticipated to be greater than

50 feet below ground surface.

3.6 GEOLOGIC HAZARDS

3.6.1 General

Geologic and seismic hazards are those hazards that may impact a site due to the surrounding geologic

and seismic conditions. Geologic hazards include landslides, flooding and erosion, subsidence, and poor

soil conditions. Seismic hazards include phenomena that occur during or soon after an earthquake, such as

primary ground rupture, strong ground shaking, liquefaction and seismically induced settlement. The

potential for these hazards to impact the site have been assessed at a feasilbility level and are summarized

in the following sections. Our assessment of these hazards was based on guidelines established by the

California Division of Mines and Geology (1986 and 1997A).

Our assessment of geologic and seismic hazards suggests that there is little to no potential for landslides,

subsidence, fault surface rupture, liquefaction, and seismic settlement, and some potential for flooding

and erosion, poor soil conditions, and strong ground shaking. With appropriate mitigation, all identified

geologic and seismic hazards are considered less than significant. To the extent of the information

available for this investigation, geologic and seismic hazards do not appear to represent a “fatal flaw” for

the proposed development.

3.6.2 Landslides

The proposed project lies in the relatively flat-lying Antelope Plain, where landslides would not be

expected to occur. Therefore, landslides are not anticipated to pose a hazard to the proposed project.

3.6.3 Flooding and Erosion

Flooding and the consequent erosion associated with flooding are those hazards that are the result of

concentrated flow of stormwater during torrential rains. Based on both our review of published maps and

on observations during our site work, site topography is relatively flat, void of significant drainages or

collection areas, and inclined gently toward the northeast at average gradients of approximately 1 percent.

The southern portion of the site is not located within a 100-year flood zone, but is located within a 500-

year flood zone on the official Federal Emergency Management Agency (FEMA) Flood Insurance Rate

Map of the area (Kern County, Unincorporated and Incorporated Areas Community Panel # 06029 0625

E and Community Panel # 06029 1175 E, effective date September 26, 2008). Therefore, the potential for

flooding and erosion within the southern portion of the site is considered to be low.



The northern portion of the site is located within the 100-year flood zone according to the official FEMA

Flood Insurance Rate Map of the area (Kern County, Unincorporated and Incorporated Areas Community

Panel # 06029 0625 E and Community Panel # 06029 1175 E, effective date September 26, 2008).

Therefore, there is some potential for flooding within the northern portions of the site during the lifetime

of the development. Appropriate drainage and flood control measures should be incorporated into project

designs for portions of the site within the 100-year flood zone.

3.6.4 Subsidence

The extraction of water or petroleum from sedimentary source rocks can cause the permanent collapse of

the pore space previously occupied by the removed fluid. The compaction of subsurface sediments by

fluid withdrawal will cause subsidence of the ground surface overlying a pumped reservoir. If the volume

of water or petroleum removed is sufficiently great, the amount of resulting subsidence may be sufficient

to damage nearby engineered structures. Significant quantities of water or petroleum are not being

extracted beneath the area occupied by the site. Subsidence is therefore not anticipated to pose a

significant hazard to the project site, barring such extraction in the future.

3.6.5 Poor Soil Conditions (Expansive, Collapsible, or Corrosive Soils)

Expansive soils are fine-grained soils (generally high plasticity clays) that can undergo a significant

increase in volume with an increase in water content and a significant decrease in volume with a decrease

in water content. Changes in the water content of a highly expansive soil can result in severe distress to

structures constructed on or against the soil.

As indicated on the boring logs (see Appendix A), fine-grained, highly plastic, and potentially expansive

soils were encountered in the near surface during our subsurface investigation. Further testing and

analysis of site soils should be performed as part of a design phase study. Proposed structures may require

special designs to mitigate the adverse effects of expansive soils.

Collapsible soils are those that undergo settlement upon wetting, even without the application of

additional load. The process of collapse with the addition of water is known as hydrocompaction.

Hydrocompaction occurs when water weakens or destroys the bonds between soil particles and severely

reduces the bearing capacity of the soil. Typical collapsible soils are lightly colored, are low in plasticity

and have relatively low densities. Collapsible soils are typically associated with alluvial fans, windblown

materials, or colluvium. Because the project site is located on an alluvial fan, there is some potential for

collapsible soils. The potential for collapsible soils would need to be addressed during the design phase

of the project and if collapsible soils are found to occur at the site, mitigation measures may be necessary

to reduce or eliminate the hazard.

Corrosive soils are materials that have the potential to adversely impact buried metallic pipes, concrete,

and other underground structures due to their chemical makeup. Factors that influence soil corrosivity

include pH, electrical resistivity, and chemical constituents (chloride, sulfate, etc.).

Based on our review of the Soil Survey maps for the project site (USDA Soil Conservation Service,

1988), near surface soils are typically slightly acidic to slightly alkaline (pH = 6.6 – 8.4), are highly



corrosive to uncoated steel, and are mildly to moderately corrosive to concrete materials. On the basis of

this information, there is a potential for site soils to be moderately to severely corrosive to metallic and

concrete building materials. Further testing and analysis of site soils is recommended as part of a design

phase study to evaluate the chemical activity of onsite soils and their potential impact on buried metallic

pipes and other underground structures. Mitigation measures may be necessary to reduce or eliminate the

hazard.

3.6.6 Primary Ground Rupture

Primary ground rupture is ground deformation that occurs along the surface trace of the causative fault

during an earthquake. No active faults are known to exist within the subject site. Further, there is no

geomorphic expression of faulting in the site vicinity. The site is not included within the boundaries of an

“Earthquake Fault Zone” as defined by the State of California in the Alquist-Priolo Earthquake Fault

Zoning Act (California Division of Mines and Geology, 1997B). Therefore, primary ground rupture is

not considered a hazard to the project.

3.6.7 Strong Ground Motion

The site is located within a seismically active region that is well-known for active faulting and historic

seismicity. Because the site is in a seismically active region, it follows that it will be subjected to future

seismic shaking and strong ground motion resulting from seismic activity along local and more distant

active faults. As such, structural improvements should be designed to accommodate expected strong

ground shaking.

3.6.8 Liquefaction

Liquefaction is a phenomenon whereby, during periods of oscillatory ground motion caused by an event

such as an earthquake, the pore-water pressure in a loose, saturated granular soil and some fine-grained

soils increases to the point where the effective stress in the soil is zero and the soil loses a portion of its

shear strength (initial liquefaction). Structures founded on or above potentially liquefiable soils may

experience bearing capacity failures, vertical settlement (both total and differential) and lateral

displacement (due to lateral spreading of the ground). The factors known to influence liquefaction

potential include soil characteristics (particle-size distribution, plasticity, water content), relative density,

presence or absence of groundwater, stress tensor (effective confining stresses, shear stress) and the

intensity and duration of the seismic ground shaking. The granular soils most susceptible to liquefaction

are loose, saturated sands and non-plastic silty soils located below the water table.

The potential for liquefaction at the site is considered to be low. This is due to the absence of near surface

groundwater and the generally dense, finer-grained, cohesive nature of the subsurface materials.

However, no specific information is available relative to the material and groundwater conditions at

depths greater than those explored by the borings for this investigation (26 feet), and no judgment can be

rendered concerning the deeper material.



3.6.9 Seismically Induced Settlement

Seismically induced settlement may occur as a result of liquefaction, but also when relatively soft or loose

soils are densified during earthquake shaking. Subsurface conditions susceptible to this hazard include

loose or porous, poorly cemented soils or soft bedrock near the ground surface. As indicated on the

Boring Logs (Appendix A), the project site is underlain by alluvial materials that are relatively dense in

place. Therefore, we consider the potential for differential seismically induced settlement to be low at the

site. However, no specific information is available relative to the material and groundwater conditions at

depths greater than those explored by the borings for this investigation (26 feet), and no judgment can be

rendered concerning the deeper material.



4.0 CONCL US I ONS AND RE C OM ME NDAT I ONS

4.1 GENERAL

Based on the results of URS’ geotechnical investigation, the site appears suitable, from a geotechnical

standpoint and at a feasibility level, for the proposed development of a solar plant. This conclusion is

predicated on the following: (1) the project is as described in the RFP and herein; (2) the conclusions and

recommends provided herein and in any addenda are incorporated in the design and construction of the

facility; (3) URS conducts more detailed geotechnical investigations for final design of the project; and

(4) URS observes in real time the subsurface conditions encountered during construction and evaluates

these together with the information presented in this report and confirms the recommendations in this

report or, if appropriate, makes such additional recommendations as may be necessary.

The following sections provide feasibility-level recommendations for project features.

4.2 SHALLOW FOUNDATIONS

The RFP provided loads and settlement criteria for PV panel support structures, transformers (large and

small) and a pre-engineered O&M Building; these are tabulated in Section 1.0. NextLight typically

provides shallow spread footings to support the transformers and pre-engineered O&M Building; the PV

panel support structures may be supported on either shallow or deep foundations. The deep foundation

option for the PV panel support structures is addressed in Section 4.3.

URS concludes that the transformers, O&M Building and PV panel support structures, with loads as

stated in Section 1.0, may be founded on shallow spread footings supported on a pad of compacted fill to

help control differential settlements and potential heave due to potentially expansive clay. However, the

use of deep foundations for the PV panel support structures, covered in Section 4.3, may prove to be a

better choice from the standpoints of performance and cost. URS recommends that the base of the shallow

spread footings be embedded at least 18 inches below the overlying ground or slab-on-grade surface. The

ground under the spread footings should be prepared as recommended in this section and in Section 4.4.

NextLight may also consider founding the PV panel support foundations at grade, i.e., with no

embedment. Based on discussions with BV, URS understands that the PV panel supports are quite

flexible and tolerate significant movement, more than is actually reflected in the value in Section 1.0.

Several factors should be considered: most of the site is a plowed field; clays that may be expansive were

found near the surface in part of the site; erosion may undermine footings with no embedment; and the

depth and effects of frost penetration. These factors should be studied in more detail by more detailed

geotechnical investigations. With respect to the plowed field and expansion clay issues, careful study

should be made of the upper few feet of the site. Perhaps shallow test pits with in-place density tests are

the best means of doing this. NextLight may elect to treat erosion as a maintenance issue, to be dealt with

as it occurs. The depth of frost penetration may be relatively slight. The generalized map presented by

U.S. Navy Department of the Navy (1986, Figure 7) suggests it is on the order of 5 inches.



Because some of the site soil is judged to be expansive, it may be necessary to mitigate this condition, at

least in some areas of the site. If this proves to be case during more detailed geotechnical investigations, it

may be necessary to overexcavate the ground under the foundations and floor slab area and place a pad of

compacted, relatively impervious, non-expansive fill material. For feasibility planning purposes, the pad

of non-expansive fill material should extend at least 3.0 feet below the base of the foundations and to a

lateral distance of at least 3.0 feet beyond the footing perimeter. For the O&M Building, the ground

should be overexcavated under the floor slab to the same elevation as the building footings. In addition,

the ground surface around the O&M Building perimeter should slope downward at least 5 percent away

from the structure for a distance of at least 5 feet and at least 2 percent for an additional 10 feet. Rainfall

falling on the roof should be collected by a gutter and downspout system and discharged at a safe distance

from the building to avoid extra infiltration near the building. No plants requiring irrigation should be

allowed within 20 feet of the O&M Building.

Assuming sand is used to construct the fill pad under the footings, the coefficient1 of vertical subgrade

reaction for a one-foot square plate, kv1, is estimated as 350 pounds per cubic inch (300 tons per cubic

foot) based on the estimated material characteristics. If a low-plasticity clay is used, to construct the fill

pad under the footings, the coefficient of vertical subgrade reaction for a one-foot square plate, kv1, is

estimated as 175 pounds per cubic inch (150 tons per cubic foot) based on the estimated material

characteristics. These values assume that the material is not saturated; if the material were saturated the

coefficient of subgrade reaction would be less.

The coefficient of subgrade reaction for a one-foot square plate is as classically defined in Terzaghi

(1955) and Scott (1981). The kv1 values must be adjusted for size effects to account for the “range of

influence” of the loaded area or “effective diameter of the slab’s reaction area”, B, which, due to the load

distribution provided by the reinforced concrete mat, is larger than the actual loaded area (Terzaghi 1955),

but may be much smaller than the footing or mat. Additional project details, including the values of B

developed by the structural engineer and the results of additional site subsurface exploration, will be

needed to prepare more detailed recommendations for kv.

Sustained lateral forces, such as lateral earth pressures, and transient lateral forces, such as the horizontal

component of seismic forces, may be applied to structures and their foundations. Resistance to lateral

displacement due to such forces may result either from sliding resistance on the base of the foundation or

from passive resistance on the sides of the foundation. If sliding friction and passive resistance are

combined for the purposes of checking resistance to sliding, only one-half of the passive resistance

calculated according to the following paragraph should be considered.

For feasibility planning, the ultimate passive earth pressure acting on the sides of a footing in an area of

horizontal ground may be taken as 400 lbs/ft2 per foot of depth (equivalent fluid weighing 400 lbs/ft3).

This value applies provided the ground surface adjacent to the footing is essentially horizontal for a

distance of a least 2.5 times the vertical distance from the ground surface to the bottom of the footing. A

factor of safety of at least 2.0 should be applied to the ultimate passive earth pressure for the static case

and a factor of safety of at least 1.5 should be applied for cases that include transient loading (e.g.,

1 The coefficient of subgrade reaction is sometimes referred to as a “modulus”, but does not have the units of amodulus, that is, its unit are force per distance cubed, rather than force per distance squared.



seismic and wind gusts, but not sustained wind load). For ground that is not covered with concrete or

asphalt flatwork, the upper 12 inches of ground should be considered non-existent for the purposes of

selecting the ground surface for use in the passive pressure calculation. On the opposite side of the

footing, the active pressure, which reduces the effective passive resistance, should be taken as 40 lbs/ft2

per foot of depth (equivalent fluid weighing 40 lbs/ft3).

For spread footings cast directly on the subgrade, an ultimate coefficient of friction of 0.35 may be used.

A factor of safety of at least 1.5 should be applied to the ultimate frictional resistance for the static case

and a factor of safety of at least 1.3 should be applied for cases that include transient loading (seismic and

wind gusts, but not sustained wind load).

4.3 DEEP FOUNDATION FOR PV SUPPORT STRUCTURE

As an alternative to shallow spread footings, BV indicated that the PV support structures may also be

supported on W6x9 steel I-beams driven into the ground, and the RFP indicates that steel posts and

concrete piers can also be used. URS concludes that the PV panel support structures, with loads as stated

in Section 1.0, may be founded on deep foundations. Considering the presence of potentially expansive

clay at the site, the use of deep foundations for the PV panel support structures may be a better choice

from the standpoints of performance and cost than shallow footings, which were discussed in Section 4.2.

Either type of deep foundation, cast-in-drilled-hole (CIDH) piles (i.e., concrete piers) or driven steel

sections (an H-pile or pipe), should be workable from a geotechnical standpoint. If lateral loading is

predominantly unidirectional (as it may be if wind loading far exceeds seismic loading), then a section

with a greater structural resistance in one direction relative to the orthogonal direction may be

advantageous.

URS does not anticipate that any unusual difficulty will be encountered during pile construction by a

competent specialist contractor. URS does not anticipate that groundwater will be encountered by the

excavations for CIDH piles. Where sand is penetrated during excavation of CIDH piles, some moderate

caving may occur, but excessive caving is not anticipated based on the performance of the three borings

advanced for this investigation.

4.4 EARTHWORK

URS understands that the Project will consist of excavation for the foundations for the O&M Building,

transformers, and, if spread footings are used, PV panel support structures. Trenches for buried electrical

cables are also planned. No site grading has been identified at this feasibility stage of the project.

4.4.1 General Grading Requirements

In case of any conflict between this report and the project specifications for earthwork, the Geotechnical

Engineer-of-Record should be consulted to verify which provision should prevail.



Earthwork will consist primarily of excavation for footings, removal of any unsuitable soil identified by

the Geotechnical Engineer-of-Record and replacement with compacted fill, subgrade preparation, placing

and compacting fill, and electrical trench excavation and backfill.

4.4.2 Demolition

URS is unaware of any required demolition. However, if any demolition is identified, URS recommends

that it observe and document demolition operations of below-grade items in the vicinity of project

facilities. Documentation should include the limits and extent of demolition and cavities created by such

operations. Soil that is loosened or disturbed by demolition must also be removed. No facilities should be

constructed in areas where removals and/or fill placement have not been documented.

Pipes that are abandoned should be removed or backfilled with concrete. If a pipe is not entirely removed,

the end(s) of the remaining pipe should be permanently blocked so that soil or other material cannot enter

the pipe that is left in place.

4.4.3 Site Preparation and Removals

Prior to earthwork, the areas to be cut, to receive fill, or to receive stockpile materials should be cleared

and stripped of all debris, deleterious materials, organics and vegetation, and remnants resulting from site

demolition. At the time of the field investigation in December 2009, there appeared to be little vegetation

that would require removal. Cleared and grubbed material, as well as all rubble waste that may be

encountered or created, should be disposed of onsite in an area with no facilities or offsite.

URS should observe the exposed excavated surface to confirm that satisfactory subgrade soil, appropriate

for the allowable bearing pressure and other geotechnical parameters recommended, has been

encountered. If loose, soft, or otherwise unsuitable materials or undocumented fill are encountered at

planned subgrade level, overexcavation or other mitigative measures may be required. The Contractor

should obtain URS’ approval of the planned subgrade or bottom of overexcavation before placing any fill

or foundation rebar on the bottom.

Prior to placement of fill, the bottoms of excavations should be scarified to a depth of at least 6 inches,

moisture conditioned to be at or slightly above the optimum water content, and compacted to at least 95

percent relative compaction if the subgrade is coarse-grained and 90 percent if it is fine-grained. The

terms “coarse-grained” and “fine-grained” soils are as defined by ASTM D 2487, "Standard

Classification of Soils for Engineering Purposes (Unified Soil Classification System)". URS recommends

compacting wet of the optimum water content obtained by ASTM D 1557 (and closer to the optimum

water content given by ASTM D 698) to help reduce the formation of a flocculated soil structure that is

brittle and more susceptible to settlement with the addition of moisture over time. Relative compaction is

a measure of the degree of soil compaction and is defined as the ratio of the in situ dry density divided by

the material's maximum dry density as measured by a reference test procedure. The reference test

procedure for this project is ASTM D1557, “Standard Test Methods for Laboratory Compaction

Characteristics of Soil Using Modified Effort (56,000 ft-lbf/ft3 (2,700 kN-m/m3))”.



4.4.4 Site Dewatering and Control of Water

To provide dry working conditions and to protect excavations from erosion, debris, and local sloughing,

surface drainage should be controlled near open trenches and should be directed away from them. Trench

operations should not interfere materially with the surface or subsurface flow without adequate provisions

to correct for the interference. If any excavation floods, the contractor should remove wet soils to the

depth indicated by URS.

Based on the site subsurface explorations, it is unlikely that groundwater will be encountered during

construction. However, localized perched water conditions may exist within the subsurface, especially

given the presence of clay layers at shallow depth that could trap infiltration or cause it to move laterally.

Adequate measures should be in place in order to insure proper drainage of excavations in the event that

perched water is encountered.

4.4.5 Fill Materials

URS anticipates that the materials that will be excavated are mainly lean and fat clays (CL and CH per

ASTM D 2487) and silty and clayey sand (SM and SC). While the sands should be suitable for reuse in

fills that will be overlain by project facilities, the reuse of the clays should be avoided due to their

potential to change volume (swell or contract) in response to changes in water content. In addition, when

the clay is excavated, it will likely be below the optimum water content and in the form of large coherent

clods. In these circumstances, the earthwork contractor will have difficulty modifying the water content of

the material to obtain the correct water content to allow compaction to be achieved.

Engineered Fill material for use in the pad of fill placed beneath the shallow foundations or the O&M

building slab-on-grade should consist of sand excavated from the project site or imported from offsite

sources that is suitable for use in constructing engineered fill. Suitability should be determined by the

Geotechnical Engineer-of-Record. Materials for use as Engineered Fill should not contain rocks or hard

lumps greater than 6 inches in maximum dimension and should have at least 80 percent passing the 9.5

mm (3/8 inch) sieve and at least 5 percent passing the 0.075 mm (No. 200) sieve. Engineered Fill

materials should be free of organics, debris, or other deleterious materials. Particles greater than ¾ inch in

size (gravel and cobbles) should be placed so that they are completely surrounded by the compacted fill

matrix. The Contractor must not nest rocks, nor should it use perishable, spongy, hazardous, or other

improper materials in filling. Provided that surface vegetation, topsoil and other deleterious materials are

removed, it is URS’ opinion that the on-site sands are suitable for use as Engineered Fill.

Any imported materials should have water-soluble sulfate and chloride contents that are less than 1000

parts per million and 500 parts per million, respectively, pH greater than 7.0, minimum electrical

resistivity greater than 6,000 ohms-centimeter and Expansion Index less than 20.

Most of the site soil encountered in the borings would be suitable for fill material that is placed against

the sides of the transformer pads and PV panel support structure footings.



4.4.6 Trenches

Trenches will be required for electric cabling; the trenches will have a width of approximately 3 to 4 feet

and a depth relative to finished grade of up to 4 feet. DC cabling will be mostly direct burial (underground

feeder (UF)) cable. AC medium voltage will include some direct burial cable and some routed in conduit.

URS recommends that direct burial cable and conduit have a minimum cover of 24 inches from the

finished grade to provide adequate structural cover.

Trenches for conduits and direct burial cables may be excavated manually or with mechanical trenching

equipment. Walls of trenches should be essentially vertical. Two types of material are used for trench

backfill: Initial Backfill Material and Common Backfill Material.

Initial backfill should consist of satisfactory materials free from rocks 25 millimeters (1 inch) or larger in

any dimension or free from rocks of such size as recommended by the manufacturer, whichever is

smaller.

Common Trench Backfill Material may consist of site soil or import material approved by URS that is

free of organic matter, clay balls, and debris. Common Trench Backfill material should have no cobbles,

stones, or soil lumps (chunks) greater than 100 mm (4 inches) in any dimension, and no less than 75

percent by weight passing the 25 mm (l inch) sieve. Where particles larger than 1 inch in any dimension is

included in the material, these particles should be completely surrounded by finer soil; no nesting of

particles should be allowed.

Most site soils encountered at shallow depth in the three borings should be usable as Common Trench

Backfill Material. However, as discussed above, URS anticipates that the contractor will have difficulty in

bringing the clays to uniform, proper water content.

Initial Backfill Material should be placed and compacted with approved tampers from the bottom of the

trench to an elevation at least one foot above the cable or conduit. The backfill should be brought up

evenly on both sides of the cable or conduit for its full length.

The remainder of the trench (above the Initial Backfill Material) should be filled with satisfactory

Common Trench Backfill Material.

4.4.7 Fill Placement and Compaction

All fill materials, except trench backfill, should be placed in lifts not exceeding 6 to 8 inches in thickness,

measured after spreading and before compaction. The fill material should be at water contents above the

optimum water content prior to being placed on the subgrade or fill surface for compaction. Coarse-

grained soils (generally sands) as defined by ASTM D 2487 should be compacted to at least 95 percent

relative compaction and fine-grained soils to at least 90 percent relative compaction. URS recommends

compacting wet of the optimum water content obtained by ASTM D 1557 (and closer to the optimum

water content given by ASTM D 698) to help reduce the formation of a flocculated soil structure that is

brittle and more susceptible to settlement with the addition of moisture over time. Appropriate lightweight

compaction equipment should be used above and adjacent to pipes, walls or footings, if any, so as not to



overstress or displace them. Where lightweight equipment is used, the lift thickness should not exceed 4

inches, measured after spreading and before compaction.

Trench backfill material should be placed in lifts not exceeding 10 inches in thickness, measured after

spreading and before compaction. The fill material should be at water contents above the optimum water

content prior to being placed on the trench bottom or fill surface for compaction. If a trench passes under

or within the zone of influence of a structure or foundation the trench backfill should be compacted to a

relative compaction of at least 95 percent if the backfill material is coarse grained (generally sands) as

defined by ASTM D 2487; fine-grained backfill should be compacted to a relative compaction of at least

90 percent. In locations where the trench backfill cannot affect any facility, the compaction requirement

can be reduced: coarse-grained soils should be compacted to at least 90 percent relative compaction and

fine-grained soils to at least 85 percent relative compaction.

Water flooding or jetting methods of compaction should not be permitted.

The field density of fill should be determined in accordance with the Sand Cone Method (ASTM D 1556,

"Standard Test Method for Density and Unit Weight of Soil in Place by the Sand-Cone Method") or the

Nuclear Method (ASTM D 6938, "Standard Test Methods for In-Place Density and Water Content of Soil

and Soil-Aggregate by Nuclear Methods (Shallow Depth)").

4.5 TEMPORARY EXCAVATIONS

URS anticipates that the materials exposed in site excavations could consist of sandy or clayey alluvial

soils. All temporary excavations should conform to Cal-OSHA guidelines. Based on the results of the

field investigations, the alluvial soils may be classified as Types A, B or C (depending on location) for the

purpose of OSHA classification of earth materials exposed in temporary excavations (Appendix A of

subpart P of 29 CFR part 1926). With restrictions, Type A, B and C soils generally correspond to

allowable temporary slope inclinations of 0.75:1, 1.0:1 and 1.5:1 (horizontal to vertical), respectively. For

shallow (less than 5 feet) foundation excavations constructed near vertical, the granular alluvial soils may

also have low cohesion and the potential to cave and slough. This general recommendation is based

largely on observations made of conditions exposed at the ground surface and in nearby road cuts and

should be reviewed frequently as the excavations progress. An Excavation Competent Person, as defined

by California-OSHA, should review all excavations and have responsibility for excavation safety during

construction.

The maximum anticipated depth of trench excavations for electrical conduits is four feet. These trench

excavations should be made with nearly vertical sides. Sheeting and shoring should be used whenever

required by safety considerations, as discussed in the previous paragraph. Cal/OSHA regulations do not

require that trenches that are less than five feet deep be shored, but deeper trenches should be sheeted and

shored in all cases.

Steep slopes are particularly susceptible to shallow slope sloughing in periods of heavy rainfall or upslope

surface runoff. This is particularly true for fill slopes constructed of soil, as well as slopes in the

alluvium/colluvium. It may be necessary to protect the slope face during periods of heavy rainfall by

diverting surface runoff away from the temporary slope or other measures. It may also be necessary to



treat the slopes with some type of protective material to keep them from drying out depending on the

length of time that the temporary slope will be exposed and whether it would be possible to remove the

desiccated material prior to refilling the excavation.

4.6 ANTICIPATED EXCAVATION CONDITIONS

URS anticipates that the materials that will be excavated are mainly very stiff lean and fat clays (CL and

CH per ASTM D 2487) and medium dense silty and clayey sand (SM and SC). The soils generally

reacted strongly when exposed to dilute hydrochloric acid, indicating the presence of carbonate

cementation. Some hardpan was encountered in boring BV-1 at about 22 feet below ground surface. URS

anticipates that the excavations for footings and trenches can be made with such conventional excavation

methods as the bucket of large backhoes or excavators or bulldozers with rippers. Scrapers with push

dozers might also prove workable for extensive areas of excavation.

4.7 RECOMMENDATIONS FOR FUTURE GEOTECHNICAL INVESTIGATION

It is our understanding that NextLight will be considering the feasibility of developing the Lost Hills site

for a solar power plant, using the information in this report as well as information developed by others.

Assuming NextLight decided to develop the project, additional geotechnical studies would be appropriate,

as discussed below.

Additional exploration of the site would be required to obtain more detailed information concerning

subsurface conditions and to obtain samples for laboratory testing of classification properties, engineering

properties and corrosion potential vis-à-vis concrete and steel. For the PV panel supports, URS

recommends a maximum spacing of 200 feet between subsurface explorations.

A mixture of exploration methods would seem to be well-suited to the size of the site. These could

include backhoe pits, hollow-stem auger borings with SPT and thin-wall tube sampling, and Cone

Penetration Test soundings (CPTs). Opening a pit with a backhoe allows the geologist to get a detailed

view of the subsurface that cannot be achieved with borings or CPTs. They also facilitate the taking of

bulk samples and allow performance of in-place density tests, which are much more reliable than

laboratory density tests. CPTs effectively provide a continuous profile of the subsurface but do not yield a

sample of the material; rather the type of material and its engineering properties are estimated using the

parameters measured during the test.

If the project will be designed for seismic, then the properties (preferably the shear-wave velocity) of the

material in the upper 100 feet should be determined. In addition, depth to groundwater should be

measured; if groundwater is deep (deeper than at least 50 feet), then liquefaction can be excluded on the

basis that the soil is unsaturated and thus is not subject to classical earthquake-induced liquefaction.

In the laboratory, some testing should be performed to evaluation key engineering properties as well as

corrosion potential vis-à-vis concrete and steel.



5.0 L IM ITAT I ONS

URS has prepared this report for the exclusive use of NextLight and BV for feasibility evaluation of the

site for the proposed solar plant and preliminary planning. No other use is anticipated or authorized by

URS. The report may be used only by the client for the project and purposes described herein, within a

reasonable time period during, which the onsite and offsite conditions affecting the project should not

change due to the actions of man or nature. This report is not suitable for final design or construction

purposes.

This report presents recommendations for feasibility evaluation/preliminary planning of the proposed

solar plant. The findings and recommendations presented in this report are based upon soil conditions

inferred from URS’ limited site explorations, interpolation of the soil conditions between exploration

locations, and extrapolation of these conditions throughout the proposed site area. The extent of

investigation as well as specific exploration locations were dictated by the RFP. The findings and

recommendations are further based on the assumption that the subsurface conditions do not deviate

appreciably from those reported and those assumed. In view of the general geology of the area, the

potential for encountering conditions different from those assumed cannot be discounted. If different

conditions are encountered, they must be brought to URS’ attention in a timely manner so that the need

for revised recommendations can be evaluated. In the event that changes in design loads or structural

characteristics described in this report or in documents provided to us are made, URS should review its

design recommendations and their applicability to the revised design plans. In this way, any required

supplemental recommendations can be made in a timely manner.

Professional judgments presented in this report are based on URS’ evaluations of the technical

information gathered, its understanding of the proposed construction, and its general experience in the

geotechnical field. URS’ services have been performed according to generally accepted geotechnical

engineering practices followed in the project area at the time the services were provided. No warranty is

expressed or implied. The report is issued with the understanding that the owner and client choose the risk

they decide to incur by the expenditures involved in the engineering and construction.



6.0 RE FE RE NCE S

California Division of Mines, 1943, Geologic Formations and the Economic development of the Oil and Gas

Fields of California, Bulletin 118, 773 p.

CDMG (California Division of Mines and Geology), 1975. Geologic Map of California, Bakersfield Sheet.

Scale 1:250,000.

California Division of Mines and Geology (CDMG), 1986, “Guidelines To Geologic/Seismic Reports” DMG

Note 42.

California Division of Mines and Geology 1997A. Guidelines for Evaluating And Mitigating Seismic

Hazards In California. Special Publication 117.

California Division of Mines and Geology, 1997B. Fault Rupture Hazard Zones in California. Special

Publication 42, 26p.

Norris, R. M., and Webb R. W, 1990. Geology of California. Second edition. John Wiley and Sons Inc. 541

p.

Scott, R.F., 1981. Foundation Analysis. Englewood Cliffs, New Jersey: Prentice-Hall, Inc.

Terzaghi, K. 1955. “Evaluation of Coefficients of Subgrade Reaction”. Géotechnique, 5, 297-326. London,

England: Institution of Civil Engineers.

USDA (United States Department of Agriculture) Soil Conservation Service, 1988. Soil Survey of Kern

County California, Northwestern Part - http://www.nrcs.usda.gov/

U.S. Department of the Navy, 1986. Soil Mechanics. Design Manual 7.01. Alexandria, Virginia: Naval

Facilities Engineering Command.

USGS (United States Geological Survey), 1921, Geology and Petroleum Resources of Northwestern Kern

County California, Bulletin 721, 48 p.

SITE LOCATION AND REGIONALGEOLOGIC MAP

Project: NextLight Lost Hills

Project Number: 29871499

Date: Jan. 2010

Figure 1

LEGENDQf Holocene alluvial fan deposits

Qp Plio-Pleistocene nonmarine

Geologic Contact: dashed where approximately located, gradational of inferred

Fault: dashed where approximately located; dotted where concealed

SAFZ San Andreas Fault Zone

Base map modified from:CDMG, Bakersfield Sheet, 1965, Scale 1:250,000

Site

SA

FZ

North

Scale 1:250,000

0 1 2 3 4 5 6 Miles

BV-3

BV-2

BV-1

Site Plan and Approximate Boring Locations

LegendBoring and Adjacent Resistivity TraversesSoil Boring Location

URS Corporation

January 2010Figure: 2

Proj No: 29871499Project: NextLight Lost Hills

500 0250 Feet

File Path: S:\Anthony\Praveen\mxd\Fresno.mxd, Date: January 5, 2010 3:17:54 PM

Appendix A

Borings

T:\!12\NextLight Lost Hills\9000 Deliverables\9101 Rpt\Final\Rpt-LostHills.doc/ 1/26/2010 A-1

Appendix A

Borings

IntroductionOn December 18, 2009, URS and Technicon Engineering Services, Inc. (Technicon), of Fresno,

California, advanced three test borings at the site. The boring locations, depths, sample types and sample

intervals were defined by the owner’s engineer. The field work was observed by a URS geotechnical

engineer.

Boring MethodologyTechnicon provided a Central Mine Equipment Company (CME) 55 drilling rig equipped with 3-3/4 inch

inside diameter hollow-stem augers and operators to perform the drilling and sampling operations. Each

of the three borings was advanced to a total depth of 26.5 feet.

Figure 2 shows the approximate locations of the borings, designated BV-1, -2 and -3. The latitudes and

longitudes of the boring locations are measured by GPS and are indicated on the respective borings logs.

The logs also record the ground elevation at the borings indicted by the GPS unit; however, GPS

elevations are typically less accurate than horizontal locations.

The borings were advanced following ASTM D 1452, “Standard Practice for Soil Exploration and

Sampling by Auger Borings”.

Soil samples and blow count data were obtained for each boring. The samples were taken with Standard

Penetration Test (SPT) 2-inch split barrel samplers following ASTM D 1586, "Standard Test Method for

Penetration Test and Split-Barrel Sampling of Soils". One sample was taken with a thin-wall tube

following ASTM D 1587, “Standard Practice for Thin-Walled Tube Sampling of Soils for Geotechnical

Purposes”.

The SPTs consisted of driving a standard thick-wall sampling barrel into the soil at the bottom of the

boring a total length of 18 inches or to refusal, whichever occurs first, with a 140 pound out-of-hole

automatic hammer falling 30 inches. According to information provided by Technicon Engineering

Services, Inc., the hammer efficiency is approximately 88 percent. A summary of hammer efficiency

measurements made on April 20, 2009, for another project is in Table A-1 following this text.

The SPT sampler has a nominal outside diameter of 2 inches; the sampling shoe (entrance) has a nominal

inside diameter of 1-3/8 inches; and the sampling barrel has a nominal inside diameter of 1-1/2 inches.

Liners were not used, as is common California practice.

The number of blows required to drive the SPT sampler was recorded for every 6 inches of penetration.

The first 6 inch increment of penetration is considered to be a "seating interval" in highly disturbed soils

at the base of the borehole; and therefore, the corresponding blow count is not normally taken into

consideration. The total number of blows for the last 12 inch penetration, commonly referred to as the “N

value”, has been used to reflect the penetration resistance. The degree of relative density of granular soils

T:\!12\NextLight Lost Hills\9000 Deliverables\9101 Rpt\Final\Rpt-LostHills.doc/ 1/26/2010 A-2

and the degree of consistency of cohesive soils are generally described on the boring logs according to the

following conventional correlation:

Granular Soils Cohesive Soils

SPT Blow Count, N Description SPT Blow Count, N Description

< 4 Very Loose < 2 Very Soft

4 - 10 Loose 2 - 4 Soft

10 - 30 Medium Dense 4 - 8 Medium Stiff

30 - 50 Dense 8 - 15 Stiff

> 50 Very Dense 15 - 30 Very Stiff

> 30 Hard

The relative density and consistency descriptions given on the logs may deviate from the correlation for a

number of reasons, including reliance on other test results, the engineer's judgment based on manual

manipulation of the sample, and simplification of the logs to increase readability. It is widely accepted

that SPT blow count correlations, including those above, are overly simplistic and the blow counts should

be adjusted for other factors, which may include, depending on the application, the effective vertical

pressure at the sample depth and the details of the sampling system (such as hammer efficiency, rods,

sampler details, and techniques used). The relative density and consistency descriptions on the logs are

based on the unadjusted SPT blow count recorded in the field and reported on the logs.

The boring logs were initiated in the field by the URS field engineer who recorded soil characteristics,

observations, sample locations, and other drilling information. The earth materials encountered were

visually classified in general accordance with the Unified Soil Classification System (ASTM D 2488,

“Standard Practice for Description and Identification of Soils (Visual-Manual Procedure)”). The final

boring logs were prepared on the basis of visual observation of the samples and results of the laboratory

tests.

As permitted by Kern County regulations, the boreholes were backfilled with the boring cuttings

following completion. Any excess cuttings were spread around the borehole location in a manner to avoid

damaging the area or leaving it in an unsightly condition. URS’ engineer transported the samples to URS’

geotechnical laboratory for review and testing.

ResultsThe key to the logs of boring is presented after this text and Table A-1, and the logs of the borings are

presented in alphanumerical order following the key. Groundwater was not encountered in the borings.

Table A-1. Summary of SPT Energy Measurements

Average Max CompressionRigSerial No.

RodSegmts

(1)

PenetrationDepth(s)

UncorrectedN-value

(2)

CorrectedN-value

(3)

AverageHammer

Rate

AverageTransferred

Energy(4)

EnergyTransferRatio

(4)

MeasuredTop Stress

ImpactTop Force

(5)

ft ft blows N60 bpm ft-lbs % ksi kips

CME 55 Drill Rig

306115 -20 20.0 - 21.5 9 12 49 290 83 27 31

-25 25.0 - 26.5 16 23 50 300 86 27 32

-30 30.0 - 31.5 13 19 51 310 88 27 32

-35 35.0 - 36.5 12 17 50 306 87 27 31

-40 40.0 - 41.5 72 / 10” - 51 310 89 27 32

-45 45.0 - 46.5 41 62 52 316 90 27 32

-50 50.0 - 51.5 98 / 11” - 52 320 91 27 32

Overall System Performance 51 307 88 27 32

Notes:1. Combined length of rod segment(s) excluding penetrometer length as reported by others.2. Uncorrected N-value, number of hammer blows required to advance sampler the last 12 inches, unless noted otherwise.3. Corrected N-value,number ofhammer blows required toadvance sampler the last12 inches, corrected for calculated energy transfer ratio (ETR).4. Average transferred energy at transducer location; ratio of (EMX) to theoretical potential energy of hammer.5. Average Maximum computed driving compression Force at transducer location.6. These measurements made on April 20, 2009, for another project.

ML

OH

Project Location: Lost Hills, CA

SM

SC

GW

GW-GM

CL

SILTY SAND

CL-ML

Other (see remarks)COBBLES and BOULDERSBOULDERS

PT

SILTY GRAVEL

CLAYEY GRAVEL


Static Water Level Reading (long-term)

Poorly graded GRAVEL with SAND

Poorly graded GRAVEL with SILT and SAND

Poorly graded GRAVEL with CLAY and SAND(or SILTY CLAY and SAND)

FIELD AND LABORATORY TESTS

WATER LEVEL SYMBOLS

Dynamic Coneor Hand DrivenRotary Drilling

Shelby Tube

NX Rock Core

Bulk Sample

Piston Sampler

HQ Rock Core

CLAYEY SAND

Diamond Core

GRAVELLY fat CLAY with SAND

ORGANIC fat CLAYORGANIC fat CLAY with SANDORGANIC fat CLAY with GRAVELSANDY ORGANIC fat CLAY

Elastic SILT with SAND

UU

SILTY, CLAYEY GRAVEL

SANDY fat CLAY

PPR

SL

Poorly graded SAND

Poorly graded SAND with GRAVEL

Poorly graded SAND with SILT and GRAVEL

SANDY lean CLAY

Unconsolidated Undrained Triaxial

UC

SILTY CLAYSILTY CLAY with SAND

Pressure MeterPMPocket Penetrometer

GRAVELLY fat CLAY

TV

SANDY fat CLAY with GRAVEL

Well-graded SAND with CLAY and GRAVEL(or SILTY CLAY and GRAVEL)

ORGANIC lean CLAY with SANDORGANIC lean CLAY with GRAVELSANDY ORGANIC lean CLAYSANDY ORGANIC lean CLAY with GRAVEL

Fat CLAY with SANDFat CLAY with GRAVEL

Well-graded SAND

ORGANIC elastic SILT with SAND

Well-graded GRAVEL with SILT

Well-graded GRAVEL with CLAY and SAND(or SILTY CLAY and SAND)

Well-graded SAND with CLAY (or SILTY CLAY)

Poorly graded GRAVEL

Poorly graded GRAVEL with CLAY(or SILTY CLAY)

Poorly graded SAND with SILT

Poorly graded SAND with CLAY (or SILTY CLAY)

Well-graded SAND with SILT and GRAVEL

Lean CLAY

COBBLES

SANDY ORGANIC elastic SILT with GRAVELGRAVELLY ORGANIC elastic SILTGRAVELLY ORGANIC elastic SILT with SAND

GW-GC

GP-GM

GP-GC

GM

Poorly graded SAND with CLAY and GRAVEL(or SILTY CLAY and GRAVEL)

SILTY, CLAYEY SAND with GRAVEL

Project: NextLight

Well-graded GRAVEL with SAND

Standard Penetration Test (SPT)

CLAYEY SAND with GRAVEL

SILTY SAND with GRAVEL

SILT with SAND

DRILLING METHOD SYMBOLS

SILTY CLAY with GRAVELSANDY SILTY CLAYSANDY SILTY CLAY with GRAVEL

GRAVELLY SILTY CLAY with SAND

SILT with GRAVELSANDY SILT

SANDY SILT with GRAVEL

PEAT

Well-graded GRAVEL with SILT and SAND

Well-graded GRAVEL with CLAY (or SILTY CLAY)

GRAVELLY ORGANIC fat CLAY

GRAVELLY SILTY CLAY

Well-graded SAND with GRAVEL

Sheet 1 of 2

Key to Log of Boring

GRAVELLY lean CLAY with SAND

GROUP SYMBOLS AND NAMES

GRAVELLY ORGANIC SOIL

OL/OH

ORGANIC SOILORGANIC SOIL with SANDORGANIC SOIL with GRAVEL

SANDY ORGANIC SOIL with GRAVEL

MH

GRAVELLY ORGANIC SOIL with SAND

WA

SANDY elastic ELASTIC SILT

SANDY ORGANIC SOIL

M

GRAVELLY lean CLAY

SAMPLER GRAPHIC SYMBOLS

OH

SA

Well-graded GRAVEL

Poorly graded GRAVEL with SILT

Group Names

EI

Standard California Sampler

SILTY GRAVEL with SAND

CLAYEY GRAVEL with SAND

Modified California Sampler

Well-graded SAND with SILT

Figure A-1

First Water Level Reading (during drilling)

SC-SM

Graphic / Symbol Graphic / Symbol Group Names

SILTY, CLAYEY SAND

GC

GP

GC-GM

SP-SC

SW

SP

SW-SM

SILTY, CLAYEY GRAVEL with SAND

Lean CLAY with SAND

GRAVELLY SILTGRAVELLY SILT with SAND

SILT

ORGANIC SILT with SANDORGANIC SILT with GRAVELSANDY ORGANIC SILT

Lean CLAY with GRAVEL

SANDY lean CLAY with GRAVEL

ORGANIC lean CLAY

GRAVELLY ORGANIC lean CLAYGRAVELLY ORGANIC lean CLAY with SAND

Fat CLAY

Elastic SILT with GRAVELSANDY elastic SILT

C

GRAVELLY ORGANIC fat CLAY with SAND

Elastic SILT

ORGANIC elastic SILT with GRAVEL

SW-SC

SP-SM

Liquid Limit, Plastic Limit, Plasticity Index

GRAVELLY elastic SILT with SAND

SANDY elastic SILT with GRAVEL

OL

OL

CH

Static Water Level Reading (short-term)

SANDY ORGANIC fat CLAY with GRAVEL

ORGANIC elastic SILT

SANDY ORGANIC SILT with GRAVELGRAVELLY ORGANIC SILTGRAVELLY ORGANIC SILT with SAND

ORGANIC SILT

PI

GRAVELLY elastic SILT

Pocket Torvane

CL

Auger Drilling

Consolidation

Collapse Potential

CP Compaction Curve

CR Corrosion, Sulfates, Chlorides

CU Consolidated Undrained Triaxial

DS Direct Shear

Expansion Index

Moisture Content

OC Organic Content

P Permeability

Particle Size Analysis

PL Point Load Index

R-Value

SE Sand Equivalent

SG Specific Gravity

Shrinkage Limit

SW Swell Potential

Unconfined Compression - SoilUnconfined Compression - Rock

UW Unit Weight

Minus #200

Crumbles or breaks with considerablefinger pressure.

< 0.25Very Soft

It takes considerable time rolling and kneading to reach the plastic limit. The thread can be rerolled several timesafter reaching the plastic limit. The lump can be formed without crumbling when drier than the plastic limit.

SOIL PARTICLE SIZE

Crumbles or breaks with handling orlittle finger pressure.

Will not crumble or break with fingerpressure.

1.0 - 2.0> 2.0

Weak

Moderate

CoarseNo. 4 Sieve to 3/4 inchFine

CoarseCobble

PLASTICITY OF FINE-GRAINED SOILS


Particles are present but estimatedto be less than 5%

0.25 - 0.50

Low

Very StiffHard

Medium Stiff 0.50 - 1.0 0.50 - 1.0 0.25 - 0.50

< 0.120.12 - 0.25

SPT N60 - Value (blows / foot)

0.25 - 0.50Soft

PocketPenetrometer (tsf)

2.0 - 4.0> 4.0

2.0 - 4.0> 4.0

< 0.25Easily penetrated several inches by thumb

PERCENT OR PROPORTION OF SOILS

Can be penetrated several inches by thumbwith moderate effort

Torvane (tsf)Unconfined CompressiveStrength (tsf) Field Approximation

Damp but no visible water

Dry

Project: NextLight

Readily indented by thumb but penetratedonly with great effort

3 to 12 inches

Loose

Very Loose

30 to 45%

Little 15 to 25%

Few 5 to 10% 3/4 inch to 3 inches

> 12 inches

Descriptor

Gravel

Trace

Criteria

Boulder

SandNo. 10 Sieve to No. 4 Sieve


Absence of moisture, dusty, dry to the touch

Passing No. 200 Sieve50 to 100%Mostly

Descriptor Size

CONSISTENCY OF COHESIVE SOILS

Stiff 1.0 - 2.0

Silt and Clay

The thread can barely be rolled, and the lump cannot be formed when drier than the plastic limit.

Strong

NOTE: This legend sheet provides descriptors andassociated criteria for required soil description componentsonly. Refer to Caltrans Soil and Rock Logging, Classification,and Presentation Manual (July 2007), Section 2, for tables ofadditional soil description components and discussion of soildescription and identification.

Medium

CriteriaDescriptor

Some

The thread is easy to roll, and not much time is required to reach the plastic limit; it cannot be rerolled afterreaching the plastic limit. The lump crumbles when drier than the plastic limit.

No. 200 Sieve to No. 40 Sieve

A 1/8-inch thread cannot be rolled at any water content.

CriteriaDescriptor

Indented by thumbnail with difficultyReadily indented by thumbnail

Easily penetrated several inches by fist

High

Nonplastic

CEMENTATION

5 - 10

Medium Dense

Dense

Descriptor

Figure A-1

Key to Log of Boring

1.0 - 2.0

31 - 50

Sheet 2 of 2

> 50

FineMedium No. 40 Sieve to No. 10 Sieve

Descriptor

Visible free water, usually soil is belowwater table

Criteria

11 - 30

0 - 4

Wet

APPARENT DENSITY OF COHESIONLESS SOILS MOISTURE

Moist

Descriptor

0.50 - 1.0

Very Dense

Drill BitSize/Type

BoreholeBackfill

M. Luebbers

@22 Feet - Drillerreports resistantdrilling.

SA(44)

SA(35)

LL=57; PI=34; WA(94)

Plowed field

Location

Technicon Engineering Services,Inc.

Checked By

Soil cuttings

17

Latitude 35.62869; Longitude -119.85094

26.5 feet

12/18/09

Automatic Hammer;140 lbs / 30-inch drop

GroundwaterLevel(s)

Hollow Stem AugerDrillingMethod

P. Yerra

Total Depthof Borehole

201

17

15

12

17

11

3

23

4

16

Bottom of borehole at 26.5 feet bgsBackfilled with soil cuttings

moist

hard pan layer; 1- to 2-inch rocky fragments in cuttings

Interbedded Clayey SAND (SC) and Silty SAND (SM); medium dense; lightyellowish-brown; dry to moist; trace fine gravel; angular

2

Fat CLAY (CH); very stiff; light olive brown; dry to moist; medium plasticity

8-inch HSA drill bit

8

7

6

5

Interbedded Clayey SAND (SC) and lean CLAY (CL)

0

5

10

15

20

25

30Figure A-2

Project: NextLight

Sheet 1 of 1

Report: GEO_10_SNA_CT; File: BV1 - 3.GPJ; 1/8/2010 BV-1


Log of Boring BV-1Project Location: Lost Hills, CA

HammerData

Type

Graphic Log

Approx. 589 feet MSL

Not Encountered

DrillingContractor Surface Elevation

SPT

REMARKS AND

OTHER TESTS

SamplingMethod(s)

Logged ByDate(s)Drilled

Drill RigType CME 55

Water

Content, %

Depth,

feet

Elevation,

feet

SAMPLES

Drilling M

ethod

Sampling

Resistance,

blows/foot

Number

Dry Unit

Weight, pcf

MATERIAL DESCRIPTION

LL=36; PI=19; SA(69)

BoreholeBackfill


@23 Feet - Drillerreports resistantdrilling. Encounteredgravels

SA(65)

LL=40; PI=21

SA(65)

LL=40; PI=23

Plowed field


LL=48; PI=27; WA(97)

14

GroundwaterLevel(s)

Checked By

Hollow Stem AugerDrillingMethod

Drill BitSize/Type


M. Luebbers


P. Yerra

Push

8

20

13

14

12

32

1

16

24

13

9


Silty SAND (SM); dense; light brown; moist; trace gravel

Sandy lean CLAY / Clayey SAND (CL/SC); very stiff (medium dense); lightbrown; moist

stiff

Lean CLAY and Sandy lean CLAY (CL); stiff; light brown; low plasticity

Sandy lean CLAY (CL); stiff; light yellowish-brown; low plasticity

Lean CLAY (CL) with lense of Silty SAND (SM); medium stiff to stiff (loose);light yellowish brown; low plasticity

17

26.5 feet

8

7

6

5

4

3

2

Water

Content, %

0

5

10

15

20

25

30Figure A-3

Project: NextLight

Sheet 1 of 1

Log of Boring BV-2

12/18/09



Sampling

Resistance,

blows/foot


Graphic Log


Not Encountered

DrillingContractor Surface ElevationCME 55

SPT, ShelbyHammerData

SamplingMethod(s)


Drill RigType

Location

8-inch HSA drill bit

Soil cuttings

Number

Elevation,

feet

SAMPLES

Drilling M

ethod

Type

Depth,

feet

Dry Unit

Weight, pcf

MATERIAL DESCRIPTION REMARKS AND

OTHER TESTS

@20 Feet - Drillerreports resistantdrilling.

Drill BitSize/Type

BoreholeBackfill


SA(9)


LL=30; PI=13

LL=50; PI=30

WA(78)

Plowed field

Soil cuttings

P. Yerra


18

12/18/09

GroundwaterLevel(s)

Checked By

DrillingMethod


M. Luebbers

Hollow Stem Auger

1

49

14

9

11

13

11

9

4

19

28


Poorly graded SAND with Silt (SP-SM); very dense; light yellowish-brown;moist; few coarse gravel

Clayey SAND with GRAVEL (SC); medium dense; light brown; moist

Interbedded Silty SAND (SM) and Clayey SAND (SC); loose, brown; moist;mostly medium sand

trace gravel; increase in sand content; cemented

stiff; decrease in sand content

Sandy fat to lean CLAY (CH/CL); very stiff; brown; moist2

3

8

7

6

5

Interbedded Clayey SAND (SC) and Silty SAND (SM); loose, lightyellowish-brown; moist; some fine and coarse gravel (up to 1-inch)

0

5

10

15

20

25

30Figure A-4

Project: NextLight

Sheet 1 of 1

Sampling

Resistance,

blows/foot

26.5 feet8-inch HSA drill bit



Log of Boring BV-3Project Location: Lost Hills, CA

Type

Graphic Log


Not Encountered

DrillingContractor Surface ElevationCME 55

SPTSamplingMethod(s)


Drill RigType

Location

HammerData

Number

Depth,

feet

Elevation,

feet

SAMPLES

Drilling M

ethod

Dry Unit

Weight, pcf

MATERIAL DESCRIPTION REMARKS AND

OTHER TESTS

Water

Content, %

Appendix B

Electrical Resistivity Testing Data

SOIL RESITIVITY FIELD TEST REPORT

Project Name: NextLight Renewable Power LLC

Traverse No.: ER-1

Test Conducted by: Praveen Yerra

Test Date: 12/17/09

Test equipment:Manufacture: Advanced Geosciences Inc

Model #: SAGA Supersting R1Serial# : SP0803249

Last calibrated date: 7/15/2009

Weather Conditions: Foggy/ CloudyTemperature: 45-55°F

Dirt Conditions: MoistRecent precipitation Rained 3 days ago

Soil composition Plowed field clayeyTerrain Rough

Electrodes Easy to insertCurrent lead cable 120 feet

Potential lead cable 65 feetElectrode Length 18 inches

Electrode diameter 0.375 inchElectrode material Statinless steel

Traverse ER-1

ELECTRODESPACING (ft.)

RESISTANCE(ohms) Probe Depth (in.) A (m) B (m)

SOILRESISTIVITY

(ohm-centimeters)

(ASTM)

2*pi()*a*100*R3 10.07 3 0.9144 0.0762 57866 3.80 3 1.8288 0.0762 436410 2.27 3 3.048 0.0762 435112 1.63 3 3.6576 0.0762 374816 1.231 3 4.8768 0.0762 377220 0.7931 3 6.096 0.0762 303825 0.4413 3 7.62 0.0762 211330 0.5762 3 9.144 0.0762 331060 0.1975 3 18.288 0.0762 2269

Average 3639

a (m) a/2X values Y values X values Y values X values X values

0.9144 0.4572 -1.37160E+00 0.00000E+00 1.37160E+00 0.00000E+00 -4.57200E-01 4.57200E-011.8288 0.9144 -2.74320E+00 0.00000E+00 2.74320E+00 0.00000E+00 -9.14400E-01 9.14400E-013.048 1.524 -4.57200E+00 0.00000E+00 4.57200E+00 0.00000E+00 -1.52400E+00 1.52400E+003.6576 1.8288 -5.48640E+00 0.00000E+00 5.48640E+00 0.00000E+00 -1.82880E+00 1.82880E+004.8768 2.4384 -7.31520E+00 0.00000E+00 7.31520E+00 0.00000E+00 -2.43840E+00 2.43840E+006.096 3.048 -9.14400E+00 0.00000E+00 9.14400E+00 0.00000E+00 -3.04800E+00 3.04800E+007.62 3.81 -1.14300E+01 0.00000E+00 1.14300E+01 0.00000E+00 -3.81000E+00 3.81000E+009.144 4.572 -1.37160E+01 0.00000E+00 1.37160E+01 0.00000E+00 -4.57200E+00 4.57200E+0018.288 9.144 -2.74320E+01 0.00000E+00 2.74320E+01 0.00000E+00 -9.14400E+00 9.14400E+00

Traverse 1Spacing (m) Coordinates

A B M N

Project Name: NextLight Renewable Power LLCTraverse No.: ER-2

Test Conducted by: Praveen Yerra

Test Date: 12/18/09

Test equipment:Manufacture: Advanced Geosciences Inc

Model #: SAGA Supersting R1Serial# : SP0803249

Last calibrated date: 7/15/2009

Weather: Temperature: 40-50°FConditions: Cloudy/Windy

Dirt Conditions: MoistRecent precipitation Mist overnight; rained 4 days ago

Soil composition Plowed field clayeyTerrain Rough

Electrodes Easy to insertCurrent lead cable 120 feet

Potential lead cable 65 feetElectrode Length 18 inches

Electrode diameter 0.375 inchElectrode material Statinless steel

Traverse ER-2

ELECTRODESPACING (ft.)

RESISTANCE(ohms) Probe Depth (in.) A (m) B (m) A/B

SOILRESISTIVITY

(ohm-centimeters)

(ASTM)

2*pi()*a*100*R3 8.55 3 0.9144 0.0762 12 49156 2.37 3 1.8288 0.0762 24 272410 1.59 3 3.048 0.0762 40 303512 1.41 3 3.6576 0.0762 48 324516 1.037 3 4.8768 0.0762 64 317820 0.8143 3 6.096 0.0762 80 311925 0.5402 3 7.62 0.0762 100 258630 0.3942 3 9.144 0.0762 120 226560 0.2152 3 18.288 0.0762 240 2473

Average 3133

a (m) a/2X values Y values X values Y values X values X values

0.9144 0.4572 2.74320E+01 2.60604E+01 2.74320E+01 2.88036E+01 2.74320E+01 2.74320E+011.8288 0.9144 2.74320E+01 2.46888E+01 2.74320E+01 3.01752E+01 2.74320E+01 2.74320E+013.048 1.524 2.74320E+01 2.28600E+01 2.74320E+01 3.20040E+01 2.74320E+01 2.74320E+013.6576 1.8288 2.74320E+01 2.19456E+01 2.74320E+01 3.29184E+01 2.74320E+01 2.74320E+014.8768 2.4384 2.74320E+01 2.01168E+01 2.74320E+01 3.47472E+01 2.74320E+01 2.74320E+016.096 3.048 2.74320E+01 1.82880E+01 2.74320E+01 3.65760E+01 2.74320E+01 2.74320E+017.62 3.81 2.74320E+01 1.60020E+01 2.74320E+01 3.88620E+01 2.74320E+01 2.74320E+019.144 4.572 2.74320E+01 1.37160E+01 2.74320E+01 4.11480E+01 2.74320E+01 2.74320E+0118.288 9.144 2.74320E+01 0.00000E+00 2.74320E+01 5.48640E+01 2.74320E+01 2.74320E+01

Traverse 2Spacing (m) Coordinates

A B M N

Page 1 (1)

Tel: (512) 335-3338Fax: (512) 258-9958

Email:[email protected] Site: http://www.agiusa.com/index.shtml

12700 Volente Rd.Austin, Texas 78726 USA

Calibration Certificate

Manufacturer: Advanced Geosciences, Inc.Description: SuperSting R1/IP, DC-Memory Earth Resistivity MeterSerial Number: SP0803249

Customer: SAGAAddress:

Date Calibrated: 6/19/2009 Date to be calibrated again: 6/19/2010______________________________________________________________________

Advanced Geosciences, Inc. hereby certifies that the above instrument meetsmanufacturer's specifications. It has been calibrated using standards whose accuracy'sare traceable to the National Institute of Standards and Technology or to the calibrationfacilities of other International Standards Organization members. Alternatively,accuracy's have been derived from accepted values of natural physical constants, or bythe ratio type of self-calibration techniques.______________________________________________________________________

Standard UsedMfg. Model Cal date Due date Std.AccuracyFluke Voltmeter 189 7/15/09 7/15/10 MFG SPECTektronix Oscilloscope TDS224 7/15/09 7/15/10 MFG SPEC______________________________________________________________________

Procedure: AGI service and calibration routines for the SuperSting R1/IP,document #4006 rev 1.4, and document #4009 rev 1.5

Check or Adjust:1. Receiver VFC offset: Adjusted2. Receiver Filter Frequency: Adjusted3. Receiver gain settings 0-11: Adjusted4. Transmitter Filter Frequency: Adjusted5. Transmitter VFC gain: Adjusted6. High voltage converter gain: Adjusted7. Autoranging function: Checked8. Transmitter current generator: Adjusted9. Battery measurement function: Checked10. Temperature measurement function: Checked

Issued By: Leroy Garcia Issue Date: 6/19/09Lead Tech

T:\!12\NextLight Lost Hills\9000 Deliverables\9101 Rpt\Draft\Rpt draft-LostHills.doc/ 1/8/2010 B-1

Appendix C

Laboratory Testing

T:\!12\NextLight Lost Hills\9000 Deliverables\9101 Rpt\Draft\Rpt draft-LostHills.doc/ 1/8/2010 C-1

Appendix C

Laboratory Testing

URS performed water (moisture) content tests on selected samples in accordance with ASTM D 2216,

"Standard Test Method for Laboratory Determination of Water (Moisture) Content of Soil and Rock by

Mass". This test method defines water content in the manner generally used in geotechnical practice: the

ratio of the weight of water in the specimen to the weight of solid material, expressed as a percentage.

The test results can be used to help judge the strength of clays using the liquidity index (requires an

estimate of the Atterberg Limits) and the need to add or remove moisture from the soil prior to

compaction (requires an estimate of the optimum water content). The water content values are shown in

Table C-1, Summary of Laboratory Test Results, and on the boring logs at the approximate depths at

which the samples were taken.

URS measured the fines content of selected samples in accordance with Percent finer than No. 200 sieve

ASTM D 1140, “Standard Test Methods for Amount of Material in Soils Finer than No. 200 (75-μm)

Sieve”. Fines content is the percent passing the 0.075 mm (No. 200) sieve, i.e., the ratio of the dry mass

of soil particles passing a 0.075 mm sieve to the dry mass of all soil particles, expressed as a percentage.

The samples were prepared by the wet preparation. The fines content values are shown in Table C-1 and

on the boring logs at the approximate depths at which the samples were taken, e.g., WA(97).

URS performed particle-size distribution tests on selected samples in accordance with ASTM D 6913,

“Standard Test Methods for Particle-Size Distribution (Gradation) of Soils Using Sieve Analysis”. The

samples were prepared by the wet preparation. The test results were used to aid in classification of soil

type. Abbreviated test results are tabulated in Table C-1 and more complete results are presented on

Figure C-1, Particle-Size Distribution Curves. In addition, the fines content values are shown on the

boring logs at the approximate depths at which the samples were taken, e.g., SA(35).

URS measured the liquid limits, plastic limits and the plasticity indexes of selected soil samples in

accordance with ASTM D 4318, “Standard Test Method for Liquid Limit, Plastic Limit, and Plasticity

Index of Soils”. The test results were used to aid in classification of soil type. Liquid limit, plastic limit

and plasticity index results for the individual samples tested are tabulated in Table C-1 and are shown on

the boring logs at the approximate depths at which the samples were taken. In addition, the test results

are plotted on Figures C-2 and C-3, Plasticity Chart, which are plots of plasticity index versus liquid

limit.

URS extruded and logged one thin-walled tube sample in accordance with ASTM D 2488, "Standard

Practice for Description and Identification of Soils (Visual-Manual Procedure)". The results are shown on

Figure C-4.

T:\!12\NextLight Lost Hills\9000 Deliverables\9101 Rpt\Draft\Rpt draft-LostHills.doc/ 1/8/2010 C-2

Table C-1. Summary of Laboratory Test Results

CLASSIFICATIONLOCATION INITIAL CONDITION

Limits Gradation

Explo

ratio

nN

um

be

r

Sam

ple

/S

pecim

en

Num

be

r

Depth

(ft)

US

CS

Sym

bol

Wate

rC

on

tent(%

)

Tota

lUnit

Weig

ht(p

cf)

Dry

Unit

Weig

ht

(pcf)

Liq

uid

Lim

it(%

)

Pla

stic

ityIn

dex

(%)

Liq

uid

ity

Index

Gra

vel(%

)

San

d(%

)

Fin

es

(%)

BV-1 1 2.5 CH 17.4 57 34 -0.16 94.1

BV-1 3 7.5 SC 6.2 59.2 34.6

BV-1 6 15.0 SC 2.0 54.2 43.8

BV-2 1 2.5 CL 13.8 40 23 -0.14

BV-2 2 5.0 CL 0.4 34.8 64.8

BV-2 3 7.5 CL 9.2 36 19 -0.41 0.0 31.3 68.7

BV-2 4 10.0 CL 13.0 40 21 -0.29

BV-2 6a 15.0 CL 23.8 48 27 0.10 97.3

BV-2 6b 15.7 CL 16.3 0.3 35.0 64.7

BV-3 1 2.5 SC 6.7 21.9 44.3 33.8

BV-3 2 5.0 CH 77.6

BV-3 3 7.5 CH 18.3 50 30 -0.06

BV-3 6 15.0 SC 18.6 30 13 0.12

BV-3 8 25.0SW-SM

14.9 76.3 8.8

UNIFIED SOIL CLASSIFICATION

Exploration No. Sample No. Depth (ft) SYMBOL Wn (%) LL PI % -2m Description and Classification

BV-1 3 7.5 -- -- -- Light yellowish brown clayey Sand (SC)

BV-1 6 15 -- -- -- Light yellowish brown clayey Sand (SC)

BV-2 2 5 -- -- -- Light yellowish brown sandy Clay (CL)

BV-2 3 7.5 9.2 -- -- -- Light yellowish brown sandy Clay (CL)

BV-2 6 15.5 16.3 -- -- -- Brown sandy Clay (CL)

BV-3 1 2.5 6.7 -- -- -- Light yellowish brown clayey Sand with gravel (SC)

BV-3 8 25 -- -- -- Light yellowish brown well-graded Sand with silt (SW-SM)

-- -- --

Project: NextLight Lost Hills PARTICLE-SIZE DISTRIBUTION CURVES

Project No. 29871499 Fig. C-1

0

10

20

30

40

50

60

70

80

90

100

GRAIN SIZE IN MILLIMETERS

PE

RC

EN

TP

AS

SIN

GB

YW

EIG

HT

3" 2" 1" 3/4" 3/8" 4 10 20 40 60 100 200

0.0010.010.1110100 50 20 5 2 0.5 0.2 0.05 0.02 0.005 0.002

U. S. STANDARD SIEVE SIZES

C

O

B

B

L

E

S

GRAVEL SANDSILT AND CLAY

COARSE FINE COARSE FINEMEDIUM

HYDROMETER

4"

T:\!12\NextLight Lost Hills\9000 Deliverables\9101 Rpt\Draft\App C\PSD compilation.xls

DESCRIPTION / CLASSIFICATION

BV-1 2.5 l 17.4 57 34 Light olive brown Clay (CH)

BV-2 2.5 n 13.8 40 23 Olive brown Clay (CL)

BV-2 7.5 u 9.2 36 19 Light yellowish brown sandy Clay (CL)

BV-2 10.0 13.0 40 21 Olive brown sandy Clay (CL)

BV-2 15.0 o 23.8 48 27 Olive brown Clay (CL)

BV-3 7.5 18.3 50 30 Light yellowish brown Clay with sand (CH)

Project Name: PLASTICITY CHART

Project Number: Figure C-2

NextLight Lost Hills

29871499

WATER

CONTENT (%)

BORING /

SAMPLEDEPTH (ft.)

TEST

SYMBOLLL (%) PI (%)

CL-ML

0

10

20

30

40

50

60

70

80

0 10 20 30 40 50 60 70 80 90 100 110

LIQUID LIMIT (%)

PL

AS

TIC

ITY

IND

EX

(%)

74

ML

or

OL

CL or

OL

CH

or

OH

MH or

OH

"U" LINE

"A" LINE

Plasticity 1.xls

DESCRIPTION / CLASSIFICATION

BV-3 15.0 l 18.6 30 13 Light olive brown clayey Sand (SC)

n

u

o

Project Name: PLASTICITY CHART

Project Number: Figure C-3


29871499

WATER

CONTENT (%)

BORING /

SAMPLEDEPTH (ft.)

TEST

SYMBOLLL (%) PI (%)

CL-ML

0

10

20

30

40

50

60

70

80

0 10 20 30 40 50 60 70 80 90 100 110

LIQUID LIMIT (%)

PL

AS

TIC

ITY

IND

EX

(%)

74

ML

or

OL

CL or

OL

CH

or

OH

MH or

OH

"U" LINE

"A" LINE

Plasticity 2.xls

LABORATORY LOG OF TUBE SAMPLES

Project Number: Task: Exploration Number:

Project Name: Sample Number:

Tested by: Date: Depth (ft) to @ tip

Test requested: water content, sieve, plasticity index

36" Description of Soil: Type of Test

34"

32"

30" Top of sample tube

28"

26"

24"

22"

Top of O-Ring Seal

20" 15 ft Top of sample

Olive brown Clay (CL)

18"

16"

14" 15.5 ft Olive brown Clay (CL)

Brown sandy Clay (CL)

12"

cut 10"

8" 16 ft

6"

4"

2" 16.5 ft

cut Brown sandy Clay (CL)

Tip

Figure C-4

BV-2

6

1512/28/2009 16.7

29871499 LAB


TJO

wc, sieve

wc, -#200,

PI

No

Recovery

S-### (SNA) (11/07) shelby log NLH BV02s6.xls

Documents

Appendix Geotechnical Investigation for Proposed Lost ... · PRELIMINARY GEOTECHNICAL INVESTIGATION FOR PROPOSED SOLAR PLANT, LOST HILLS, KERN COUNTY, ... Soil resistivity is calculated