geotechnical report - San Benito County

GEOTECHNICAL REPORT PANOCHE VALLEY SOLAR FARM SAN BENITO COUNTY, CALIFORNIA

Submitted to: Eric Cherniss Solargen Energy, Incorporated 2400 Stephen Creek Boulevard, Suite 700 Cupertino, CA 95014 Prepared by: ENGEO Incorporated March 26, 2010 Project No. 8924.000.000 .

Copyright © 2010 By ENGEO Incorporated. This Document May Not Be Reproduced In Whole Or In Part By Any Means Whatsoever, Nor May It Be Quoted Or Excerpted Without The Express Written Consent Of ENGEO Incorporated

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GEOTECHNICAL ENVIRONMENTAL WATER RESOURCES CONSTRUCTION SERVICES

Project No. 8924.000.000 March 26, 2010 Eric Cherniss Solargen Energy, Incorporated 2400 Stephen Creek Boulevard, Suite 700 Cupertino, CA 95014 Subject:

Panoche Valley Solar Farm San Benito County, California GEOTECHNICAL REPORT

Dear Mr. Cherniss: ENGEO prepared this geotechnical report for the Panoche Valley Solar Farm as outlined in our agreement dated February 19, 2010. We characterized the subsurface conditions at the site to provide the enclosed geotechnical recommendations for design. Our experience and that of our profession clearly indicates that the risk of costly design, construction, and maintenance problems can be significantly lowered by retaining the design geotechnical engineering firm to review the project plans and specifications and provide geotechnical observation and testing services during construction. Please let us know when working drawings are nearing completion, and we will be glad to discuss these additional services with you. If you have any questions or comments regarding this report, please call and we will be glad to discuss them with you. Sincerely, ENGEO Incorporated

Paul J. Cottingham, CEG Senior Geologist

Mark M. Gilbert, GE Principal

Jonathan C. Boland, GE Senior Engineer

2213 Plaza Drive Rocklin, CA 95765 (916) 786-8883 Fax (888) 279-2698 www.engeo.com

Solargen Energy, Incorporated Panoche Valley Solar Farm

8924.000.000 March 26, 2010

TABLE OF CONTENTS Letter of Transmittal 1.0

INTRODUCTION .........................................................................................1 1.1 1.2 1.3

2.0

FINDINGS......................................................................................................2 2.1

2.2

2.3 2.4 2.5 2.6 2.7

3.0

PURPOSE AND SCOPE .......................................................................................1 PROJECT LOCATION ........................................................................................1 PROJECT DESCRIPTION ..................................................................................2

FIELD EXPLORATION.......................................................................................2 2.1.1 Borings .........................................................................................................3 2.1.2 Electrical Resistivity Testing .......................................................................3 GEOLOGY.............................................................................................................3 2.2.1 Regional Geologic Setting ...........................................................................3 2.2.2 Geologic Mapping.........................................................................................4 SEISMICITY AND FAULTING..........................................................................5 SURFACE CONDITIONS....................................................................................5 SUBSURFACE CONDITIONS ............................................................................7 GROUNDWATER CONDITIONS......................................................................8 LABORATORY TESTING ..................................................................................8

CONCLUSIONS ............................................................................................8 3.1 3.2

3.3 3.4 3.5 3.6 3.7 3.8 3.9

FOUNDATION SUPPORT...................................................................................9 SEISMIC HAZARDS ............................................................................................9 3.2.1 Ground Rupture ...........................................................................................9 3.2.2 Ground Shaking ...........................................................................................9 3.2.3 Liquefaction ...............................................................................................10 3.2.4 Ground Lurching........................................................................................10 EXPANSIVE SOIL..............................................................................................10 2007 CBC SEISMIC DESIGN PARAMETERS...............................................11 SOIL CORROSION POTENTIAL....................................................................11 CLIMATE AND FROST/HEAVE CONDITIONS ..........................................12 EXCAVATABILITY...........................................................................................12 ON-SITE AGGREGATE SOURCES ................................................................12 HORIZONTAL DIRECTIONAL DRILLING .................................................12

4.0

CONSTRUCTION MONITORING ..........................................................12

5.0

EARTHWORK RECOMMENDATIONS ................................................13 5.1 5.2

GENERAL AREA CLEARING.........................................................................13 BUILDING AND EQUIPMENT PAD OVEREXCAVATION .......................14


5.3 5.4 5.5

5.6

6.0

6.2

7.2

INTERIOR CONCRETE FLOOR SLABS.......................................................20 7.1.1 Minimum Design Section ..........................................................................20 7.1.2 Slab Moisture Vapor Reduction.................................................................20 7.1.3 Subgrade Modulus for Structural Slab Design – Equipment Pads ............21 TRENCH BACKFILL.........................................................................................21

PAVEMENT DESIGN.................................................................................21 8.1 8.2 8.3 8.4

9.0

PILE FOUNDATIONS........................................................................................16 6.1.1 Lateral Pile Capacity..................................................................................16 6.1.2 Vertical Pile Capacity ................................................................................18 CONVENTIONAL FOOTINGS WITH SLAB-ON-GRADE .........................18 6.2.1 Footing Dimensions and Allowable Bearing Capacity..............................18 6.2.2 Reinforcement............................................................................................19 6.2.3 Foundation Lateral Resistance ...................................................................19 6.2.4 Settlement ..................................................................................................19

SLABS-ON-GRADE ...................................................................................20 7.1

8.0

ACCEPTABLE FILL..........................................................................................14 OVER-OPTIMUM SOIL MOISTURE CONDITIONS ..................................14 FILL COMPACTION .........................................................................................15 5.5.1 Grading in Structural Areas .......................................................................15 5.5.2 Underground Utility Backfill in Structural Areas ......................................15 5.5.3 Underground Utility Backfill in Non-Structural Areas..............................16 SLOPES GRADIENTS .......................................................................................16

FOUNDATION RECOMMENDATIONS ................................................16 6.1

7.0

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FLEXIBLE PAVEMENTS .................................................................................21 AGGREGATE ROADS.......................................................................................22 SUBGRADE AND AGGREGATE BASE COMPACTION ............................22 CHEMICALLY TREATED SUBGRADE ........................................................22

LIMITATIONS AND UNIFORMITY OF CONDITIONS......................23

FIGURES Figure 1: Figure 2: Figure 3: Figure 4: Figure 5: Figure 6:

Vicinity Map Regional Faulting and Seismicity Site Plan Franciscan Alluvial Fan Borings Panoche Alluvial Fan Borings Fluvial Deposit Borings

APPENDIX A – Exploration Logs APPENDIX B – Laboratory Test Data APPENDIX C – NORCAL Geophysical Test Data


1.0

INTRODUCTION

1.1

PURPOSE AND SCOPE

8924.000.000 March 26, 2010

ENGEO prepared this geotechnical report for design of the Panoche Valley Solar Farm in San Benito County, California. We prepared this report as outlined in our agreement dated February 19, 2010. Solargen Energy authorized ENGEO to conduct the scope of services outlined below: • • • • •

Service Plan Development Subsurface Field Exploration Soil Laboratory Testing Data Analysis and Conclusions Report Preparation.

For our use, we received the following: 1. RFQ, POWER Engineers, delivered via email on February 4, 2010. 2. Electronic site plan, POWER Engineers, delivered via email on March 2, 2010. 3. Panoche Valley Solar Farm Initial Study, POWER Engineers, dated August 2009. This report was prepared for the exclusive use of our client and their consultants for design of this project. In the event that any changes are made in the character, design or layout of the improvements, we must be contacted to review the conclusions and recommendations contained in this report to determine whether modifications are necessary. This document may not be reproduced in whole or in part by any means whatsoever, nor may it be quoted or excerpted without our express written consent. 1.2

PROJECT LOCATION

Figure 1 displays a Site Vicinity Map. The site is located in Panoche Valley situated in the Coast Ranges approximately 43 miles southeast of Hollister via Panoche Road and approximately 16 miles west of Interstate 5 via West Panoche Road. Figure 2 shows site boundaries, proposed improvement areas, geology, as well as our exploratory locations. The 5000-acre site occupies the majority of the Panoche Valley north of Panoche Road. Little Panoche Road trends north-south bisecting the site. The site Panoche Valley, looking northwest is generally bordered by mountains to the east and west. The southern portion of the site is generally bordered by flat cattle grazing land. -1-


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Panoche Creek cuts through the southern portion of the site. Los Aguilas Creek enters the western portion of the site and joins with Panoche Creek near the southern boundary. Additionally, an unnamed creek cuts through the very southeastern corner of the site. 1.3

PROJECT DESCRIPTION

We understand the proposed solar farm will include: • • • • •

140 to 230 Watt photovoltaic panel arrays Equipment pads including: 1000 kVA transformers and 500kW inverters Substation Electric Transmission Cable Access roads

We understand the photovoltaic arrays will likely be supported on steel pipe piles, H-Piles, or precast concrete piles. The photovoltaic panel arrays are divided into a total of 210 blocks. Each block will include photovoltaic panel strings, two transformers, and four inverters. The equipment pads with the transformers and inverters will likely be constructed on mat type foundation. The substation, also referred to as the switchyard, will house large transformers and switchgear and will also include an operation and maintenance facility. It is expected that grading will only be necessary for the substation, equipment pads for transformers and inverters within each block, and access roads.

2.0

FINDINGS

2.1

FIELD EXPLORATION

Our field exploration included two phases of drilling totaling 22 borings as well as performing 7 electrical resistivity surveys at various locations on site. We performed the first phase of our field exploration on March 8th and 9th 2010; the second phase of exploration occurred on March 16th and 17th 2010. We also performed geologic field mapping concurrently. The location and elevations of our explorations are approximate and were determined using a hand held GPS device; they should be considered accurate only to the degree implied by the method used. We describe our exploration techniques below.

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2.1.1

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Borings

We observed drilling of 22 borings and logged the subsurface conditions at each location. Boring locations are shown on Site Plan, Figure 3. We retained a Mobile B24 drill rig and crew to advance the borings using 4-inch diameter solid flight auger methods. Borings were advanced to depths ranging from 15 to 51½ feet below existing grade. Borings were backfilled with drill cuttings. We obtained soil samples at various intervals using standard penetration tests and a California Modified Sampler (3-inch O.D. split spoon with 2.5-inch I.D. liners). The blow counts were obtained by dropping a 140-pound hammer through a 30-inch free fall. The sampler was driven 18 inches and the number of blows were recorded for each 6 inches of penetration. Unless otherwise indicated, the blows per foot recorded on the boring log represent the accumulated number of blows required to drive the last 1 foot of penetration; the blow counts have not been converted using any correction factors. When sampler driving was difficult, penetration was recorded only as inches penetrated for 50 hammer blows. We used the field logs to develop the report logs in Appendix A. The logs depict subsurface conditions at the exploration locations for the date of exploration; however, subsurface conditions may vary with time. 2.1.2

Electrical Resistivity Testing

We retained NORCAL Geophysical Consultants to perform electrical resistivity testing to provide design recommendations for electrical grounding systems. Using a 2-person crew headed by a licensed California Professional Geophysicist, they tested in seven locations to evaluate the in-situ soil resistivity. At each location, a Wenner electrode array was used to obtain measurements oriented in roughly east-west and north-south directions. Electrode spacings of 2, 5, 7, 10, 20, and 40 feet were used to obtain electrical resistivity measurements to a depth of about 25 feet below grade. The data is recorded as apparent resistivity versus electrode spacing, and presented in a tabular format. The report, attached in Appendix C, describes the method used, field procedures, and a tabulation of the results. 2.2

GEOLOGY

2.2.1

Regional Geologic Setting

The site is located in the Coast Ranges geomorphic province, which includes many separate ranges, coalescing mountain masses, and many structural valleys. These mountain ranges are made up largely of marine sedimentary rocks that have been highly faulted, folded, and altered by orogenic processes. Panoche Valley is mapped as Quaternary Alluvium (Dibblee, Panoche Valley Quadrangle, 1975) consisting of sediments transported by creeks and alluvial fans from the surrounding mountains. -3-


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The mountains to the east and south of the site are mapped as Panoche Formation consisting of marine sandstone and shale. The mountains to the west are mapped as Franciscan Formation consisting of highly sheared marine sandstone, shale and volcanics. We have divided the Quaternary Alluvium into three major geologic units: Franciscan Alluvial Fans, Panoche Alluvial Fans, and Fluvial Deposits. We present a detailed discussion of these units below. 2.2.2

Geologic Mapping

An ENGEO geologist observed the geologic features at surface and reviewed aerial photographs. We mapped the geology and summarize our major findings on the Site Plan, Figure 3. The geomorphology of Panoche Valley suggest three major sources of alluvium: Franciscan Alluvial Fans, Panoche Alluvial Fans, and Fluvial Deposits. Additionally, we observed areas of young fluvial deposits in the Panoche Creek channel and young alluvial deposits in the Los Aguilas Creek channel. Alluvial fans are fan-shaped landforms formed by water-transported material generally deposited where steep terrain meets a valley. Material transported in a steep gradient creek reaches a flatter gradient and is deposited, commonly in braded streams. Material deposited in alluvial fans is often poorly sorted and is closely related to the material in the nearby parent terrain. Fluvial deposits are materials transported and deposited by river or creek systems. These systems generally deposit sediments as they meander through gentle terrain. As the river or creek bends, it erodes on its outer bank and deposits material on the inside of the bend. Material deposited in this manner is generally coarse-grained gravel and sand. Fine-grained material, such as silt and clay, typically get deposited when the river or creek overtops its banks and suspended fine grained material settles out over the flood plain. This process generally results in intermittent pockets of sand, silt, clay, and gravel. We observed a topographic feature near the western boundary of the site that could be fault related. This feature, shown on Figure 3, is a linear break in slope extending approximately 3,700 feet northeasterly. This feature abruptly slopes down from an upper terrace to a lower terrace; the vertical elevation difference between the two is approximately 10 feet. We describe, in detail, soils of each geologic region in Section 2.5, Subsurface Conditions. -4-

Possible fault related topographic feature, looking northeast downhill


2.3

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SEISMICITY AND FAULTING

California is an active seismic region with numerous active earthquake faults. We include a Regional Faulting and Seismicity Map as Figure 2. Nearby active faults include the Ortigalita to the north, Great Valley to the east, and the San Andreas to the west. An active fault is defined by the California Geologic Survey as one that has had surface displacement within the last 11,000 years (Hart, 1997). The site is not located within a currently designated Alquist-Priolo Earthquake Fault Zone. We used the software program EQFAULT Version 3.00b (Blake, 2000) to search a 100 km radius in order to locate the nearest known mapped active faults and summarize them in the table below. Table 1 Nearest Known Active Faults Fault Distance from Site (miles) Ortigalita 5.7 Great Valley 10 7.9 Great Valley 9 9.9 Great Valley 11 12.2 San Andreas (Creeping) 15.6

Moment Magnitude 7.1 6.4 6.6 6.4 6.2

Although there are no known mapped active faults crossing the site, as described in Section 2.2.2 we observed a topographic feature near the western boundary of the site that could be fault related. We provide recommendations regarding this possible fault in Section 3.2.1. 2.4

SURFACE CONDITIONS

According to the site plan provided by POWER Engineers site grades range from Elevation 1,500 feet (Datum: 0 feet = Mean Sea Level) in the southwest to Elevation 1,200 feet near the southern boundary. The majority of the site gently slopes toward the middle and southern portions of the site. We observed the following site features during our reconnaissance and aerial photograph review: •

The ground surface was generally covered with short grass and was being active used for cattle grazing. A multitude of fences divide up the site into separate cattle pastures.

•

Relatively few structures are located on the site. Most of the structures appeared related to livestock operations, however one residential dwelling was located near the southern boundary of the site.

•

Wells related to livestock operations are scattered throughout the site. -5-


8924.000.000 March 26, 2010

•

As described above, we observed a topographic feature near the western boundary of the site that could be fault related.

•

Existing overhead transmission lines cross the site trending approximately northwestsoutheast.

•

Panoche Creek – Panoche Creek meanders through the southern portion of the site. The creek generally appears confined to a relatively narrow channel and dense older deposit were frequently apparent in the creek banks. The banks were generally very steep or vertical and range from 6 to 10 feet tall and the creek bedload consists of cobble, gravel, and sand. Small terraces of younger deposits generally 1 to 4 feet tall were intermittently located inside the steep banks, generally on the inside of a bend Panoche Creek looking west in the channel. In a few locations, the geomorphology shows old creek channels outside of the current channel; this is likely due creek meanders that have been cut off. These old channel areas and the areas inside the creek banks are mapped as Young Fluvial Deposits (see Figure 3).

•

Los Aguilas Creek – Los Aguilas Creek enters the site on the western boundary as a main channel of a Franciscan Alluvial Fan and was dry at the time of our visit. In the western portion of the site the channel was generally broad, shallow, and braided in nature with gravel and cobble bedload. This channel then appeared subdued and then nonexistent toward the middle of the site. The drainage then reemerges to the south as a narrow erosional channel with little to no bedload and runs southeast, eventually meeting Panoche Creek. The Los Aguilas Creek deposits are mapped as Young Alluvial Deposits (see Figure 3).

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Los Aguilas Creek, looking east


8924.000.000 March 26, 2010

•

Unnamed Creek – An unnamed creek trends south through the very southeastern portion of the site and was dry at the time of our visit. This creek appeared erosive in nature and has little bedload. A pile of metal and wood debris was located along the bank in one area.

•

Small cattle ponds in the northern portion of the site. These appear to be relatively shallow excavations with the spoils making up a berm on the downhill side. These berms are shown on the Figure 3 as Pond Fill.

•

Small, 1- to 3-foot deep, channels trending southwest come out of the mountains and into the east side of the site. These channels are generally covered with grass and do no appear to have significant recent deposits associated with them.

•

We commonly observed animal burrows across the site. In some locations, these were extensive and significantly disturbed the ground surface.

•

We observed isolated areas with cobble and gravel at the ground surface throughout the Franciscan and Panoche Alluvial Fan geologic units.

Please refer to the Site Plan, Figure 3, for more information on site features. 2.5

Animal Burrows, Franciscan Alluvial Fan

SUBSURFACE CONDITIONS

The explorations encountered variable soil between borings, however soil was more consistent within individual geologic units we delineated on site. In general, soils were moist in the upper approximately 3 feet and decreased in moisture below 3 feet. We describe the subsurface conditions within each geologic unit below. Figures 4, 5, and 6 show borings logs grouped by geologic region. Franciscan Alluvial Fans In general, within this geologic unit, borings encountered very dense clayey or silty sand with gravel. In some areas, borings encountered very stiff silty clay with sand in the upper 3 feet. These deposits were generally reddish in color, poorly sorted, and appeared highly weathered with some easily-breakable gravel clasts.

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Panoche Alluvial Fans In general, within this geologic unit, borings encountered stiff to hard low to medium plasticity silty clay with limited areas of very dense silty or clayey sands. Soil was generally olive brown or yellowish brown in color frequently with carbonate and weak cementation. Fluvial Deposits In general, within this geologic unit, borings encountered variable pockets of sand, silt, clay and gravel. We encountered fine to medium grained loose silty sand in five borings generally in the upper 6 feet, however as deep as 13 feet in boring B-11. Deeper sand as well as gravel (boring B-9) was generally medium dense to very dense. Clay encountered was generally stiff to hard and low to medium plasticity. Silt encountered was generally stiff to hard and is some areas weakly cemented. Consult the Site Plan and exploration logs for specific subsurface conditions at each location. We include our exploration logs in Appendix A. The logs contain the soil type, color, consistency, and visual classification in general accordance with the Unified Soil Classification System. The logs graphically depict the subsurface conditions encountered at the time of the exploration. Appendix A also provides additional exploratory information in the general notes to the logs. 2.6

GROUNDWATER CONDITIONS

We did not observe static groundwater in any of our subsurface explorations. We observed minor perched water in boring B-20 at 39 feet below the ground surface. Based on available California Department of Water Resources data, groundwater is recorded within the central portion of the site approximately 60 to 100 feet below the ground surface. Fluctuations in the level of groundwater may occur due to variations in rainfall, irrigation practice, and other factors not evident at the time measurements were made. 2.7

LABORATORY TESTING

We performed laboratory tests on selected soil samples to determine their engineering properties. For this project, we performed moisture content, dry density, unconfined compression, plasticity index, expansion index, sieve, resistance value, thermal resistivity, and soil corrosion potential testing. We include the majority of the laboratory test results on the borelogs in Appendix A; we present individual test results in Appendix B.

3.0

CONCLUSIONS

From a geotechnical engineering viewpoint, in our opinion, the proposed project may be designed as planned, provided the geotechnical recommendations in this report are properly incorporated into the design plans and specifications. We summarize our conclusions below. -8-


3.1

8924.000.000 March 26, 2010

FOUNDATION SUPPORT

Based on our discussed with Solargen, we understand the desired foundation support type for the solar array panels is a single driven steel pipe, steel “H” beam, or precast concrete pile. Based on the site conditions, laboratory test data, and anticipated structural loading, it is our option that this foundation approach is feasible. Ancillary structures, including lightly loaded buildings, maintenance structures and offices can be supported on conventional shallow footings with slabson-grade. We recommend structural mat slabs for heavy equipment pads. Heavy loads associated with the substation can be supported on large spread footings or structural mat foundations. Detailed foundation recommendations for the solar arrays and lightly loaded structures are presented in Section 6.0. 3.2

SEISMIC HAZARDS

Potential seismic hazards resulting from a nearby moderate to major earthquake can generally be classified as primary and secondary. The primary effect is ground rupture, also called surface faulting. The common secondary seismic hazards include ground shaking, and ground lurching. The following sections present a discussion of these hazards as they apply to the site. Based on topographic and lithologic data, the risk of regional subsidence or uplift, soil liquefaction, lateral spreading, landslides, tsunamis, flooding or seiches is considered low to negligible at the site. 3.2.1

Ground Rupture

Although there are no known active faults crossing the property and the site is not located within an Earthquake Fault Special Study Zone, it is our opinion that the topographic feature described in Section 2.3 could possibly be fault related. Without performing additional exploration, we recommend a set back for improvements of 50 feet from this feature. If implementing a setback is undesirable, then trench exploration would be necessary to evaluate for evidence of faulting. 3.2.2

Ground Shaking

An earthquake of moderate to high magnitude could cause considerable ground shaking at the site. To mitigate the shaking effects, all structures should be designed using sound engineering judgment and the 2007 California Building Code (CBC) requirements, as a minimum. Seismic design provisions of current building codes generally prescribe minimum lateral forces, applied statically to the structure, combined with the gravity forces of dead-and-live loads. The codeprescribed lateral forces are generally considered to be substantially smaller than the comparable forces that would be associated with a major earthquake. Therefore, structures should be able to: (1) resist minor earthquakes without damage, (2) resist moderate earthquakes without structural damage but with some nonstructural damage, and (3) resist major earthquakes without collapse but with some structural as well as nonstructural damage. Conformance to the current building

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8924.000.000 March 26, 2010

code recommendations does not constitute any kind of guarantee that significant structural damage would not occur in the event of a maximum magnitude earthquake; however, it is reasonable to expect that a well-designed and well-constructed structure will not collapse or cause loss of life in a major earthquake (SEAOC, 1996). 3.2.3

Liquefaction

Soil liquefaction results from loss of strength during cyclic loading, such as imposed by earthquakes. Soils most susceptible to liquefaction are clean, loose, saturated, uniformly graded, fine-grained sands. The deep sands encountered in our borings were generally medium to very dense. In addition, groundwater was not encountered within the 51½ foot depth of our borings. For these reasons and based upon engineering judgment, it is our opinion that the potential for liquefaction at the site is low during seismic shaking. 3.2.4

Ground Lurching

Ground lurching is a result of the rolling motion imparted to the ground surface during energy released by an earthquake. Such rolling motion can cause ground cracks to form in weaker soils. The potential for the formation of these cracks is considered greater at contacts between deep alluvium and bedrock. Such an occurrence is possible at the site, but based on the site location, it is our opinion that the offset is expected to be very minor. 3.3

EXPANSIVE SOIL

We observed potentially expansive clay near the ground surface in some of the borings. Our laboratory testing indicates that these soils exhibit low to high shrink/swell potential with variations in moisture content. Expansive soils change in volume with changes in moisture. They can shrink or swell and cause heaving and cracking of slabs-on-grade, and structures founded on shallow foundations. To reduce the potential for damage to the planned improvements, we recommend that the upper 18 inches of the building and equipment pad extending at least 10 feet laterally beyond building areas, be underlain by non-expansive fill. Due to the relatively flat nature of the site, selective grading to mitigate expansive soil may not be a practical alternative and imported fill may be required. In lieu of importing non-expansive fill, it may be cost effective to lime treat the upper 18 inches of the building pad to reduce the expansion potential of the on-site soil.

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3.4

8924.000.000 March 26, 2010

2007 CBC SEISMIC DESIGN PARAMETERS

We provide the 2007 California Building Code (CBC) seismic parameters in 2 below. Table 2 2007 CBC Parameter

3.5

Design Value

Site Class 0.2 second Spectral Response Acceleration, SS 1.0 second Spectral Response Acceleration, S1 Site Coefficient, FA Site Coefficient, FV Maximum considered earthquake spectral response accelerations for short periods, SMS Maximum considered earthquake spectral response accelerations for 1-second periods, SM1 Design spectral response acceleration at short periods, SDS

D 1.49 0.48 1.0 1.52 1.49

Design spectral response acceleration at 1-second periods, SD1 Long period transition-period, TL

0.48

0.78 0.99 12

SOIL CORROSION POTENTIAL

We submitted select soil samples to an analytical lab for determination of pH, resistivity, sulfate, and chloride. The majority of the sulfate lab test results indicate the sulfate exposure may be categorized as “Negligible” in accordance with Table 19-A-4 of the California Building Code. For “Negligible” sulfate exposure, the CBC indicates that either Type I or Type II Portland Cement may be used for concrete mix designs. One sample from boring B-14 at a depth of 4 feet, indicates the sulfate exposure may be categorized as “Moderate” in accordance with Table 19-A-4 of the California Building Code. For “Moderate” sulfate exposure, the CBC indicates that Type II Portland Cement with a water content ratio of less than 0.50 may be used for concrete mix designs. The samples tested had low resistivities, indicating that they are moderately to highly corrosive to buried metal. We recommend further corrosion testing be preformed to better characterize the site. We present the analytical lab test results in Appendix B.

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3.6

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CLIMATE AND FROST/HEAVE CONDITIONS

The site is in the Coast Range, inland of the coast, but has some ocean influence that keeps temperatures from hitting more extreme highs and lows. Seasons are sharply defined with hot and dry summers with large daily temperature swings. Winters are cool, but not severe. The average summer high temperature in nearby Hollister is 82 degrees and an average winter high of 61 degrees. On average August is the warmest month and December is the coolest month. Average annual rainfall is approximately 10 inches. Snow is rare, except for the higher elevations. Due to the climate of the region and elevation of the site, we do not anticipate frost heave affecting the proposed improvements. 3.7

EXCAVATABILITY

Based on our exploration and the geologic setting of Panoche Valley, conventional grading and backhoe equipment will likely be able to excavate the soil deposits. 3.8

ON-SITE AGGREGATE SOURCES

We observed gravel and cobble that could potentially be suitable for on-site aggregate sources within the portion of Los Aguilas Creek channel mapped as Young Alluvial Deposits (see Figure 2). Borings near these deposits encountered sand with gravel within the Franciscan Alluvial Fan region, however due to the high fines content and highly weathered nature of the material, we do not consider this material suitable as an on-site aggregate source. 3.9

HORIZONTAL DIRECTIONAL DRILLING

We understand horizontal directional drilling may be considered for installation of underground electrical transmission lines. Based on our subsurface exploration program, it appears that directional drilling is a feasible construction method. For general planning purposes we recommend using our boring logs and geologic map in this report to anticipate subsurface conditions. However, for the purposes of developing a baseline of anticipated subsurface conditions for bidding, we suggest you consider additional subsurface exploration in the areas of proposed horizontal drilling.

4.0

CONSTRUCTION MONITORING

Our experience and that of our profession clearly indicates that the risk of costly design, construction, and maintenance problems can be significantly lowered by retaining the design geotechnical engineering firm to:

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8924.000.000 March 26, 2010

1. Review the final grading and foundation plans and specifications prior to construction to determine whether our recommendations have been implemented, and to provide additional or modified recommendations, if necessary. This also allows us to check if any changes have occurred in the nature, design or location of the proposed improvements and provides the opportunity to prepare a written response with updated recommendations. 2. Perform construction monitoring to check the validity of the assumptions we made to prepare this report. All earthwork operations should be performed under the observation of our representative to check that the site is properly prepared, the selected fill materials are satisfactory, and that placement and compaction of the fills has been performed in accordance with our recommendations and the project specifications. Sufficient notification to us prior to earthwork is essential. If we are not retained to perform the services described above, then we are not responsible for any party’s interpretation of our report (and subsequent addenda, letters, and verbal discussions).

5.0

EARTHWORK RECOMMENDATIONS

Earthwork recommendations are intended for use in structural areas that will support improvements such as the substation, equipment pads and roads. For the solar array areas, we understand the panels will generally follow existing topography with very little or no grading. We define “structural areas” as any area sensitive to settlement of compacted soil. These areas include, but are not limited to equipment pads, buildings, and pavement areas. Solar array areas where piles will be driven into undisturbed native soils are not considered structural areas for earthwork purposes. However, if minor grading is necessary within array areas and compacted fill will be used to support pile foundations, then these should be considered structural areas and the earthwork recommendations presented below would apply. The relative compaction and optimum moisture content of soil, rock, and aggregate base referred to in this report are based on the most recent ASTM D1557 test method. Compacted soil is not acceptable if it is unstable. It should exhibit only minimal flexing or pumping, as determined by an ENGEO representative. As used in this report, the term “moisture condition” refers to adjusting the moisture content of the soil by either drying if too wet or adding water if too dry. 5.1

GENERAL AREA CLEARING

Clear structural areas, of surface and subsurface deleterious materials including existing building foundations, slabs, buried utility and irrigation lines, pavements, debris, and designated trees, shrubs, and associated roots. Clean and backfill excavations extending below the planned

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8924.000.000 March 26, 2010

finished site grades with suitable material compacted to the recommendations presented in Section 5.5. Retain ENGEO to observe and test all backfilling. Following clearing, strip structural areas to remove surface organic materials. Strip organics from the ground surface to a depth of at least 1 to 2 inches below the surface. Remove strippings from the site or, if considered suitable by the landscape architect and owner, use them in landscape fill. It may also be feasible to mulch organics in place, depending on the amount and type of vegetation present at the time of grading as well as the proposed mulching method. If desired, ENGEO can evaluate site vegetation at the time of grading to determine the feasibility of mulching organics in place. 5.2

BUILDING AND EQUIPMENT PAD OVEREXCAVATION

In order to avoid expansive clay and mitigate possibly disturbed surface soil, we recommend overexcavation of building and equipment pads. These areas should be overexcavated a minimum of 18 inches. The excavation should be backfilled in accordance with Section 5.3 and 5.5. 5.3

ACCEPTABLE FILL

On-site soil material is suitable as fill material provided it is processed to remove concentrations of organic material, debris, and particles greater than 8 inches in maximum dimension. Fill within 18 inches of finished grade in building and equipment pad areas should be non expansive with a plasticity index less than 12, as determined by an ENGEO field representative. Imported fill materials should meet the above requirements and have a plasticity index less than 12. Allow ENGEO to sample and test proposed imported fill materials at least 72 hours prior to delivery to the site. 5.4

OVER-OPTIMUM SOIL MOISTURE CONDITIONS

The contractor should anticipate encountering excessively over-optimum (wet) soil moisture conditions during winter or spring grading, or during or following periods of rain. Wet soil can make proper compaction difficult or impossible. Wet soil conditions can be mitigated by: 1. 2. 3. 4.

Frequent spreading and mixing during warm dry weather; Mixing with drier materials; Mixing with a lime, lime-flyash, or cement product; or Stabilizing with aggregate, geotextile stabilization fabric, or both.

Options 3 and 4 should be evaluated and approved by ENGEO prior to implementation.

- 14 -


5.5

FILL COMPACTION

5.5.1

Grading in Structural Areas

8924.000.000 March 26, 2010

Perform subgrade compaction prior to fill placement, following cutting operations, and in areas left at grade as follows. 1. Scarify to a depth of at least 8 inches; 2. Moisture condition soil to at least 1 percentage point above the optimum moisture content; and 3. Compact the subgrade to at least 90 percent relative compaction. Compact the upper 6-inches of finish pavement subgrade to at least 95 percent relative compaction prior to aggregate base placement. After the subgrade soil has been compacted, place and compact acceptable fill (defined in Section 5) as follows: 1. Spread fill in loose lifts that do not exceed 8 inches; 2. Moisture condition lifts to at least 1 percentage point above the optimum moisture content; and 3. Compact fill to a minimum of 90 percent relative compaction; Compact the upper 6 inches of fill in pavement areas to 95 percent relative compaction prior to aggregate base placement. 5.5.2

Underground Utility Backfill in Structural Areas

The contractor is responsible for conducting all trenching and shoring in accordance with CALOSHA requirements. Project consultants involved in utility design should specify pipe bedding materials. Place and compact trench backfill as follows: 1. Trench backfill should have a maximum particle size of 6 inches; 2. Moisture condition trench backfill to at least 1 percentage point above the optimum moisture content. Moisture condition backfill outside the trench; 3. Place fill in loose lifts not exceeding 12 inches; and 4. Compact fill to a minimum of 90 percent relative compaction (ASTM D1557). - 15 -


8924.000.000 March 26, 2010

Jetting of backfill is not an acceptable means of compaction. We may allow thicker loose lift thicknesses based on acceptable density test results, where increased effort is applied to rocky fill, or for the first lift of fill over pipe bedding. 5.5.3

Underground Utility Backfill in Non-Structural Areas

Process, place and compact fill in accordance with Section 5.5.2, except compact to at least 85 percent relative compaction (ASTM D1557).

5.6

SLOPES GRADIENTS

Construct final slope gradients to 2:1 (horizontal:vertical) or flatter. The contractor is responsible to construct temporary construction slopes in accordance with CALOSHA requirements.

6.0

FOUNDATION RECOMMENDATIONS

We developed foundation recommendations using data obtained from our field exploration, laboratory test results, and engineering analysis. As previously mentioned, the alternatives proposed for solar array panes are use of a single driven steel pipe, H-pile, or precast concrete. Support for buildings and equipment include conventional footings with slabs-on-grade. 6.1

PILE FOUNDATIONS

The proposed solar arrays can be supported on piles (steel pipe, H beam, or precast concrete) driven into competent native materials. Pile depth and size should be determined based on the design criteria presented below. As a minimum, we recommend pile foundations for the solar arrays extend at lest 6 feet below lowest surrounding grade. 6.1.1

Lateral Pile Capacity

We developed soil profile criteria for use in design of pile foundations based on our boring logs and laboratory testing. These parameters are intended for use with the computer program LPILE5. Due to the large size of the site and the three generally distinct geologic units, we have placed lateral pile design criteria into three general categories corresponding to the least favorable conditions in each mapped geologic units shown on Figure 3. We tabulate recommended design parameters for these profiles in Tables 3 through 5 below.

- 16 -


8924.000.000 March 26, 2010

Table 3 LPILE Parameters – Panoche Alluvial Fans (Clayey Soil Profile) Depth (feet)

Unit weight (pci)

Cohesion (psi)

K static (pci)

E50

Silty Clay (CL) (modeled as soft clay - Matlock)

0-2

0.063

2

50

0.02

Silty Clay (CL) (modeled as stiff clay w/o free water- Reese)

2-15

0.063

14

750

0.006

Layer

Table 4 LPILE Parameters – Franciscan Alluvial Fans (Sandy Soil Profile) Layer

Depth (feet)

Unit weight (pci)

Friction angle (degrees)

K static (pci)

Medium Dense Silty/Clayey Sand (SM/SC) (modeled as Reese Sand)

0-5

0.067

30

90

Dense Silty/Clayey Sand (SM/SC) (modeled as Reese Sand)

5-15

0.069

34

225

Table 5 LPILE Parameters – Fluvial Deposits (Loose Sand Profile) Depth (feet)

Unit weight (pci)

Friction angle (degrees)

Loose Sand (SM) (modeled as Reese Sand)

0-13

0.061

28

--

20

--

Silty Clay (CL) (modeled as stiff clay w/o free water- Reese)

13-20

0.063

--

14

750

0.006

Layer

Cohesion K static (psi) (pci)

E50

Depending on how the ground surface is prepared prior to driving piles, there is a potential for disturbance and loss of contact in the upper 1 foot of the pile. In addition, some areas of the site may be capped by a surficial expansive clay layer that can experience some desiccation during - 17 -


8924.000.000 March 26, 2010

seasonal dry periods. We recommend that you consider some loss of support in the upper 1 foot of the driven pile and include this in the overall structural design of the foundation system. 6.1.2

Vertical Pile Capacity

Piles should be designed to resist anticipated vertical dead and live loads. We developed vertical pile capacity criteria using both skin friction and end bearing for downward resistance and skin friction only for uplift resistance. We suggest the following average values be used in design for driven piles. For downward capacity, we recommend an average end bearing value of 3,000 psf and an average skin friction value of 400 psf. For resistance to uplift forces, we recommend an average skin friction value of 200 psf. Increase the above criteria by one-third for the short-term effects of wind or seismic. The upper 1 foot of the pile should be neglected in design when determining vertical capacity to account for surface disturbance or soil desiccation. 6.2

CONVENTIONAL FOOTINGS WITH SLAB-ON-GRADE

The proposed equipment structures and support buildings can be supported on continuous or isolated spread footings bearing in competent native soil or compacted fill. As described in Section 5.2 and 5.3, building and equipment pad areas should be underlain by at least 18 inches of non-expansive fill. 6.2.1

Footing Dimensions and Allowable Bearing Capacity

We provide minimum footing dimensions for lightly loaded structures as follows in the Table 6 below. Table 6 Minimum Footing Dimensions *Minimum Footing Type Depth (in.) Minimum Width (in.) Continuous 12 12 Isolated 18 24 *below lowest adjacent pad grade Minimum footing depths shown above are taken from lowest adjacent pad grade. The cold joint between the exterior footing and slab-on-grade should be located at least 4 inches above adjacent exterior grade.

- 18 -


8924.000.000 March 26, 2010

Design foundations recommended above for a maximum allowable bearing pressure of 2,500 pounds per square foot (psf) for dead plus live loads. Increase this bearing capacity by onethird for the short-term effects of wind or seismic loading The maximum allowable bearing pressure is a net value; the weight of the footing may be neglected for design purposes. All footings located adjacent to utility trenches should have their bearing surfaces below an imaginary 1:1 (horizontal:vertical) plane projected upward from the bottom edge of the trench to the footing. 6.2.2

Reinforcement

The structural engineer should design footing reinforcement to support the intended structural loads without excessive settlement. Reinforce all continuous footings with top and bottom steel to provide structural continuity and to permit spanning of local irregularities. At a minimum, design continuous footings to structurally span a clear distance of 5 feet. 6.2.3

Foundation Lateral Resistance

Lateral loads may be resisted by friction along the base and by passive pressure along the sides of foundations. The passive pressure is based on an equivalent fluid pressure in pounds per cubic foot (pcf). We recommend the following allowable values for design: Passive Lateral Pressure: 300 pcf Coefficient of Friction: 0.30 The above allowable values include a factor of safety of 1.5. Increase the above values by onethird for the short-term effects of wind or seismic loading. Passive lateral pressure should not be used for footings on or above slopes. 6.2.4

Settlement

Provided our report recommendations are followed, and given the proposed construction (Section 1.3), we estimate total and differential foundation settlements will be less than approximately ¾ and ½-inch, respectively.

- 19 -


8924.000.000 March 26, 2010

7.0

SLABS-ON-GRADE

7.1

INTERIOR CONCRETE FLOOR SLABS

7.1.1

Minimum Design Section

We recommend the following minimum design: 1. Provide a minimum concrete thickness of 5 inches. 2. Place minimum steel reinforcing of No. 3 rebar on 18-inch centers each way within the middle third of the slab to help control the width of shrinkage cracking that inherently occurs as concrete cures. The structural engineer should provide final design thickness and additional reinforcement, as necessary, for the intended structural loads. 7.1.2

Slab Moisture Vapor Reduction

When buildings are constructed with concrete slab-on-grade, water vapor from beneath the slab will migrate through the slab and into the building. This water vapor can be reduced but not stopped. Vapor transmission can negatively affect floor coverings and lead to increased moisture within a building. When water vapor migrating through the slab would be undesirable, we recommend the following to reduce, but not stop, water vapor transmission upward through the slab-on-grade. 1. Construct a moisture retarder system directly beneath the slab on-grade that consists of the

following: a) Vapor retarder membrane sealed at all seams and pipe penetrations and connected to all footings. Vapor retarders shall conform to Class A vapor retarder per ASTM E 1745-97 “Standard Specification for Plastic Water Vapor Retarders used in Contact with Soil or Granular Fill under Concrete Slabs”. The vapor retarder should be underlain by b) 4 inches of clean crushed rock. Crushed rock should have 100 percent passing the ¾-inch sieve and less than 5 percent passing the No. 4 Sieve. 2. Use a concrete water-cement ratio for slabs-on-grade of no more than 0.50. 3. Provide inspection and testing during concrete placement to check that the proper concrete

and water cement ratio are used.

- 20 -


8924.000.000 March 26, 2010

4. Moist cure slabs for a minimum of 3 days or use other equivalent curing specified by the

structural engineer. The structural engineer should be consulted as to the use of a layer of clean sand or pea gravel (less than 5 percent passing the U.S. Standard No. 200 Sieve) placed on top of the vapor retarder membrane to assist in concrete curing. 7.1.3

Subgrade Modulus for Structural Slab Design – Equipment Pads

Provided the site earthwork is conducted in accordance with the recommendations of this report, a subgrade modulus of 150 psi/in can be used for structural slab design. The project structural engineer should design thickness and reinforcement of structural slabs to accommodate the proposed loads. We recommend a minimum concrete compressive strength of 3,000 psi. 7.2

TRENCH BACKFILL

Backfill and compact all trenches below slabs-on-grade and to 5 feet laterally beyond any edge in accordance with Section 5.5.2.

8.0

PAVEMENT DESIGN

8.1

FLEXIBLE PAVEMENTS

We obtained bulk samples of the surface soil from the site and performed R-value tests to provide data for pavement design. The results of the test are included in Appendix B and indicate R-values of 10 and 7. Because surface soils vary across the site, and due to expansion pressure variability, we judged an R-value of 5 to be applicable for design. Using estimated traffic indices for various pavement loading requirements, we developed the following recommended pavement sections using Procedure 608 of the Caltrans Highway Design Manual (including the asphalt factor of safety), presented in Table 7 and 8 below. Table 7 Recommended Asphalt Concrete Pavement Sections Section Traffic Index Asphalt Concrete (in.) Class 2 Aggregate Base (in.) 5 2½ 11 6 3 14 7 4 16

- 21 -


8924.000.000 March 26, 2010

Table 8 Recommended Asphalt Concrete Pavement Sections, with 12 inches of Lime Treated Subgrade* Section Traffic Index Asphalt Concrete Class 2 Aggregate Lime Treated (in.) Base (in.) Subgrade (in.) 5 2½ 4 12 6 3 4 12 7 4 4 12 * See Section 8.4 for lime treatment recommendations

The project civil engineer should determine the appropriate traffic indices based on the estimated equivalent single axle load frequency at specific areas on site. 8.2

AGGREGATE ROADS

Aggregate base maintenance roads subject to occasional use by lightly loaded vehicles should consist of a minimum of 20 inches of Class 2 AB placed directly on prepared subgrade. If the structural section includes 12 inches of lime treated subgrade as outlined in Section 8.3, the AB section may be reduced to 10 inches. These recommendations are consistent with a TI of 6. 8.3

SUBGRADE AND AGGREGATE BASE COMPACTION

Compact finish subgrade in accordance with Section 5.4. Aggregate Base should meet the requirements for ¾ -inch maximum Class 2 AB per section 26-1.02a of the latest Caltrans Standard Specifications. Compact the Class 2 AB section to at least 95 percent relative compaction (ASTM D1557). Moisture condition aggregate base to or slightly above the optimum moisture content prior to compaction. 8.4

CHEMICALLY TREATED SUBGRADE

Chemical treatment of fine grained soils may be utilized to improve pavement subgrade performance. If selected, we recommend uniformly mixing the subgrade soil with 4 percent high calcium lime by dry weight. The soil should be moisture conditioned to at least 3 percentage points above the optimum moisture content before mixing. The mixing should be performed in accordance with the current version of Caltrans Standard Specifications with the following exceptions: 1. Following mixing, the treated soils should be allowed to fully hydrate prior to compaction. 2. Following hydration, the treated soil should be compacted according to ASTM D-1557 to not less than 95 percent relative compaction at a moisture content at least 2 percentage points above the optimum to a non-yielding surface. - 22 -


9.0

8924.000.000 March 26, 2010

LIMITATIONS AND UNIFORMITY OF CONDITIONS

This report presents geotechnical recommendations for design of the improvements discussed in Section 1.3 for the Panoche Valley Solar Farm project. If changes occur in the nature or design of the project, we should be allowed to review this report and provide additional recommendations, if any. It is the responsibility of the owner to transmit the information and recommendations of this report to the appropriate organizations or people involved in design of the project, including but not limited to developers, owners, buyers, architects, engineers, and designers. The conclusions and recommendations contained in this report are solely professional opinions and are valid for a period of no more than 2 years from the date of report issuance. We strived to perform our professional services in accordance with generally accepted geotechnical engineering principles and practices currently employed in the area; no warranty is expressed or implied. There are risks of earth movement and property damages inherent in building on or with earth materials. We are unable to eliminate all risks or provide insurance; therefore, we are unable to guarantee or warrant the results of our services. This report is based upon field and other conditions discovered at the time of report preparation. We developed this report with limited subsurface exploration data. We assumed that our subsurface exploration data is representative of the actual subsurface conditions across the site. Considering possible underground variability of soil, rock, stockpiled material, and groundwater, additional costs may be required to complete the project. We recommend that the owner establish a contingency fund to cover such costs. If unexpected conditions are encountered, notify ENGEO immediately to review these conditions and provide additional and/or modified recommendations, as necessary. Our services did not include excavation sloping or shoring, soil volume change factors, flood potential, or a geohazard exploration. In addition, our geotechnical exploration did not include work to determine the existence of possible hazardous materials. If any hazardous materials are encountered during construction, then notify the proper regulatory officials immediately. This document must not be subject to unauthorized reuse that is, reusing without written authorization of ENGEO. Such authorization is essential because it requires ENGEO to evaluate the document’s applicability given new circumstances, not the least of which is passage of time. Actual field or other conditions will necessitate clarifications, adjustments, modifications or other changes to ENGEO’s documents. Therefore, ENGEO must be engaged to prepare the necessary clarifications, adjustments, modifications or other changes before construction activities commence or further activity proceeds. If ENGEO’s scope of services does not include on-site construction observation, or if other persons or entities are retained to provide such services, ENGEO cannot be held responsible for any or all claims arising from or resulting from the performance of such services by other persons or entities, and from any or all claims arising

- 23 -


8924.000.000 March 26, 2010

from or resulting from clarifications, adjustments, modifications, discrepancies or other changes necessary to reflect changed field or other conditions. We determined the lines designating the interface between layers on the exploration logs using visual observations. The transition between the materials may be abrupt or gradual. The exploration logs contain information concerning samples recovered, indications of the presence of various materials such as clay, sand, silt, rock, existing fill, etc., and observations of groundwater encountered. The field logs also contain our interpretation of the subsurface conditions between sample locations. Therefore, the logs contain both factual and interpretative information. Our recommendations are based on the contents of the final logs, which represent our interpretation of the field logs.

- 24 -

FIGURES Figure 1: Figure 2: Figure 3: Figure 4: Figure 5: Figure 6:

Vicinity Map Regional Faulting and Seismicity Site Plan Franciscan Alluvial Fan Borings Panoche Alluvial Fan Borings Fluvial Deposit Borings

F I G U R E S

N SA

S RA VE LA CA

RIO EGO GR

K EE CR

E I LL NV EE GR

ER LV SI

S AN

SE JO

N SA

RR

Santa Clara AL OC

TA LI GA TI OR

BE

ES EL RG VE

EN UI

BE SA

Y RE

Y BA

SA

S ITO RC LA TU

RIO EGO GR

-

N

TO

R

IZ EL

N SA

S EA DR AN

RI

A AD ON NC

N SA

S EA DR AN

RI

O NC

DA NA

NIC EA OC

San Benito NI BE

S S EA RE DR VA AN LA N CA SA

Fresno RE L IZ

TA LI GA TI OR

Q

E NT MO

SAN

RA DO LO CO PA LO

AS AN DR E SA N

Santa Cruz

Madera Merced S EA DR AN

SA

RG EN T

AN TE ZAY

SH AN NO N

ST A VI ON TE M

Mariposa Stanislaus UI N JO AQ SA N

Monterey

Kings

B-14 B-4 ER-3 B-3

B-15

B-10 ER-1

B-5

B-2 ER-5

ELECTRICAL RESISTIVITY SURVEY

B-13

B-1

B-16 B-10 ER-1

B-6

B-11A B-11

B-12

B-21 B-9 ER-4

B-22

B-8

B-20

B-17

B-7 ER-2 B-18 B-19

B-3

B-3

B-2

B-1

B-12

B-13

B-2

B-13

B-1

B-12

B-15

B-4

B-14

B-5

B-16

B-4

B-15 B-5

B-16

B-6 B-17

B-7 B-18

B-6

B-17

B-7

B-18

B-22

B-9

B-11

B-11A

B-10 B-11 B-21 B-9

B-22

B-8

B-20

B-19

B-10

B-21

B-8

B-20

B-19

APPENDIX A Key to Boring Logs Exploration Logs

A P P E N D I X A

KEY TO SOIL LOGS COARSE-GRAINED SOILS MORE THAN HALF OF MAT'L LARGER THAN #200 SIEVE

MAJOR TYPES GRAVELS MORE THAN HALF COARSE FRACTION IS LARGER THAN NO. 4 SIEVE SIZE

DESCRIPTION GW - Well graded gravels or gravel-sand mixtures

CLEAN GRAVELS WITH LESS THAN 5% FINES

GP - Poorly graded gravels or gravel-sand mixtures GM - Silty gravels, gravel-sand and silt mixtures

GRAVELS WITH OVER 12 % FINES

SANDS MORE THAN HALF COARSE FRACTION IS SMALLER THAN NO. 4 SIEVE SIZE

GC - Clayey gravels, gravel-sand and clay mixtures SW - Well graded sands, or gravelly sand mixtures

CLEAN SANDS WITH LESS THAN 5% FINES

SP - Poorly graded sands or gravelly sand mixtures SM - Silty sand, sand-silt mixtures

FINE-GRAINED SOILS MORE THAN HALF OF MAT'L SMALLER THAN #200 SIEVE

SANDS WITH OVER 12 % FINES

SC - Clayey sand, sand-clay mixtures ML - Inorganic silt with low to medium plasticity

SILTS AND CLAYS LIQUID LIMIT 50 % OR LESS

CL - Inorganic clay with low to medium plasticity OL - Low plasticity organic silts and clays MH - Elastic silt with high plasticity

SILTS AND CLAYS LIQUID LIMIT GREATER THAN 50 %

CH - Fat clay with high plasticity OH - Highly plastic organic silts and clays PT - Peat and other highly organic soils

HIGHLY ORGANIC SOILS

For fine-grained soils with 15 to 29% retained on the #200 sieve, the words "with sand" or "with gravel" (whichever is predominant) are added to the group name. For fine-grained soil with >30% retained on the #200 sieve, the words "sandy" or "gravelly" (whichever is predominant) are added to the group name.

GRAIN SIZES U.S. STANDARD SERIES SIEVE SIZE 200 SILTS AND CLAYS

10

40

CLEAR SQUARE SIEVE OPENINGS 4

3/4 "

SAND FINE

3"

MEDIUM

COARSE

FINE

COARSE

VERY LOOSE LOOSE MEDIUM DENSE DENSE VERY DENSE

COBBLES

BOULDERS

CONSISTENCY

RELATIVE DENSITY SANDS AND GRAVELS

12"

GRAVEL

SILTS AND CLAYS

BLOWS/FOOT (S.P.T.) 0-4 4-10 10-30 30-50 OVER 50

VERY SOFT SOFT MEDIUM STIFF STIFF VERY STIFF HARD

STRENGTH* 0-1/4 1/4-1/2 1/2-1 1-2 2-4 OVER 4

MOISTURE CONDITION SAMPLER SYMBOLS Modified California (3" O.D.) sampler

DRY MOIST WET

Dusty, dry to touch Damp but no visible water Visible freewater

California (2.5" O.D.) sampler

LINE TYPES S.P.T. - Split spoon sampler Solid - Layer Break Shelby Tube ______

Dashed - Gradational or approximate layer break

Continuous Core Bag Samples Grab Samples

NR No Recovery

GROUND-WATER SYMBOLS Groundwater level during drilling Stabilized groundwater level

(S.P.T.) Number of blows of 140 lb. hammer falling 30" to drive a 2-inch O.D. (1-3/8 inch I.D.) sampler * Unconfined compressive strength in tons/sq. ft., asterisk on log means determined by pocket penetrometer

LOG OF BORING B-1 Geotechnical Exploration Panoche Valle Solar Farm San Benito County, California 8924.000.000

DATE DRILLED: 3/8/2010 HOLE DEPTH: Approx. 16 ft. HOLE DIAMETER: 4.0 in. SURF ELEV (msl):

LOGGED / REVIEWED BY: DRILLING CONTRACTOR: DRILLING METHOD: HAMMER TYPE:

P. Cottingham / MMG West Coast Exploration Solid Flight Auger 140 lb. Rope and Cathead

CLAYEY SAND (SC), dark reddish brown, medium dense, moist, fine- to coarse-grained sand, trace gravel, 30% fines, weather rock fragment in sampler shoe Soil corrosion: pH 5.97; minimum resistivity 4.82 ohm-cm (x1000); chloride 7.0 ppm; sulfate 0.3 ppm. 1 Very dense, with rust staining

12.1

23

76/8"

23

5

2

10

Grades to tan, slightly moist

65/3"

Clay coating on gravel

54/6"

3

LOG - GEOTECHNICAL 8924.000.000 EXPLORATION DATABASE.GPJ ENGEO INC.GDT 3/26/10

4

15 91/11"

Boring terminated at approximately 16 feet. No groundwater encountered.

6.8

Unconfined Strength (tsf) *field approx

Dry Unit Weight (pcf)

Moisture Content (% dry weight)

Fines Content (% passing #200 sieve)

Plasticity Index

Plastic Limit

Liquid Limit

Blow Count/Foot

Water Level

DESCRIPTION

Log Symbol

Sample Type

Depth in Meters

Depth in Feet

Atterberg Limits





1 Clay coating on gravel

8.5

120.7

76

5.9

84/9"

3.2

5

2

10

Grades to tan, slightly moist

3 75/10"


4

15

Increasing gravel; mottled with reddish-brown, moist matrix Boring terminated at approximately 16 feet. No groundwater encountered.

77/12"




Plasticity Index

Plastic Limit

Liquid Limit

Blow Count/Foot 13


CLAYEY SAND (SC), reddish brown, medium dense, moist, medium- to coarse-grained sand, trace gravel, maximum gravel size 1.25 inches

Water Level

DESCRIPTION

Log Symbol

Sample Type

Depth in Meters

Depth in Feet

Atterberg Limits





SANDY CLAY (CL), dark brown, stiff, moist, low plasticity, trace gravel, 40% medium- to coarse-grained sand Resistance value: 7

5

10.3

Grades to brown, stiff 1

CLAYEY SAND (SC), light reddish brown, dense, damp Soil corrosion: pH 7.46; minimum resistivity 5.63 ohm-cm (x1000); chloride 8.0 ppm; sulfate 5.0 ppm.

26

Grades to very dense

67

5

2

10

3 63


4

15

Increasing gravel

83

5

20

6 73/12"


4.5





Plasticity Index

Plastic Limit

Liquid Limit

Blow Count/Foot

Water Level

DESCRIPTION

Log Symbol

Sample Type

Depth in Meters

Depth in Feet

Atterberg Limits

1.5* 2.25*


DATE DRILLED: 3/8/2010 HOLE DEPTH: Approx. 16½ ft. HOLE DIAMETER: 4.0 in. SURF ELEV (msl):




13.9

107.3




Plasticity Index

Plastic Limit

Liquid Limit

Blow Count/Foot

Water Level

DESCRIPTION

Log Symbol

Sample Type

Depth in Meters

Depth in Feet

Atterberg Limits

SILTY SAND (SM), brown, loose, moist, fine- to coarse-grained sand, trace gravel, with rust staining 5

SANDY SILT (ML), brown, hard, moist, 45% fine-grained sand 1 Grades to damp, light brown

4.5*

7

5

2

10

3

Trace vessicles, (old roots), weak cementation, carbonate

20

SILTY CLAY WITH SAND (CL), light brown, hard, damp, low plasticity, 40% fine-grained sand, carbonate 40


4

4.5*

29

19

10

7.3

4.5+*

Hard drilling

15

Increasing sand 5

Boring terminated at approximately 16.5 feet. No groundwater encountered.

29

4.5+*





1

12.6


17


18


Plasticity Index

35


Plastic Limit

Blow Count/Foot 8

Liquid Limit

SILTY CLAY (CL), olive brown, stiff, moist, low to medium plasticity, with fine-grained sand Expansion Index: 59.1 (medium expansion potential) Grades to decreasing moisture

Water Level

DESCRIPTION

Log Symbol

Sample Type

Depth in Meters

Depth in Feet

Atterberg Limits

3.0*

Carbonate and rust staining, trace medium-grained sand Soil corrosion: pH 7.67; minimum resistivity 0.67 ohm-cm (x1000); chloride 59.2 ppm; sulfate 675.8 ppm.

23

4.5+*

5

2

10

27

11.7

96.4

4.5+*

3 30

13.1

4.5+*


4

15

Increasing carbonate

75

4.5+*

5

20

6 74

Boring terminated at approximately 21.5feet. No groundwater encountered.

4.5+*




P. Cottingham / MMG West Coast Exploration Solid Flight Auger 140 lb. Rope and Cathead Unconfined Strength (tsf) *field approx




Plasticity Index

Plastic Limit

Liquid Limit

Blow Count/Foot

Water Level

DESCRIPTION

Log Symbol

Sample Type

Depth in Meters

Depth in Feet

Atterberg Limits

SILTY CLAY (CL), dark olive brown, stiff, moist, low plasticity, trace fine-grained sand 55

2.0* 4.5+*

Grades to hard, weakly cemented, white angular clasts 1 With carbonate

79/12"

13.2

104.8 4.5+*

5

2

10

41

4.5+*

3 76/12" 4.5+*


4

Gravel lense at 12 1/2 feet

15 84/11"

5

20

6 68/12"


4.5+*





14

18.9 19.1


18


Plasticity Index

4


Plastic Limit

32

SILTY CLAY (CL), dark olive brown, stiff, moist, low to medium plasticity, with 10% fine-grained sand


Liquid Limit

Blow Count/Foot

Water Level

DESCRIPTION

Log Symbol

Sample Type

Depth in Meters

Depth in Feet

Atterberg Limits

92.7 1.25*

1 Grades to light brown, abundant small vessicles (old roots)

13

10.9

82.3

4.5*

5

2

10

3

SANDY CLAY (CL), light brown, hard, moist, 40% fine-grained sand 22

4.5+*

SILTY CLAY (CL), yellowish brown, hard, moist, low plasticity, trace carbonates, with fine-grained sand 21

9.7

4.5+*


4

15

Grades to medium plasticity, weakly cemented

25

4.5+*

5

Gravel at 18 feet

20

6 Grades to with sand and gravel

41

9.5

81.2

4.5+*

7

25

Grades to with no gravel, carbonate Boring terminated at approximately 26 feet. No groundwater encountered.

82/9"

4.5+*





SANDY CLAY (CL), dark olive brown, very stiff, moist, 40% fine-grained sand SILTY SAND (SM), brown, medium dense, moist, fine- to medium-grained sand Grades to damp, weakly cemented

16

Grades to clayey

8





Plasticity Index

Plastic Limit

Liquid Limit

Blow Count/Foot

Water Level

DESCRIPTION

Log Symbol

Sample Type

Depth in Meters

Depth in Feet

Atterberg Limits

3.5*

47

1

5

SILTY CLAY (CL), brown, very stiff, moist, medium plasticity, with fine-grained sand 2

10

22

3.75*

3 Grades to cemented, carbonates Soil corrosion: pH 7.98; minimum resistivity 1.13 ohm-cm (x1000); chloride 118.4 ppm; sulfate 762.3 ppm.

4 LOG - GEOTECHNICAL 8924.000.000 EXPLORATION DATABASE.GPJ ENGEO INC.GDT 3/26/10

9.7

77

SILTY SAND (SM), light brown, very dense, moist, medium- to coarse-grained sand, with rust-staining

15

50/5"


4.5+*






13

94.1




Plasticity Index

Plastic Limit

Liquid Limit

Blow Count/Foot

Water Level

DESCRIPTION

Log Symbol

Sample Type

Depth in Meters

Depth in Feet

Atterberg Limits

SANDY SILT (ML), dark brown, stiff, moist, 45% fine- to medium-grained sand 7

2.5*

1 22

51

5

2

Grades to with coarse-grained sand and subangular gravel

74/12"

4.9

SILTY GRAVEL (GM), gray and brown, dense, damp

10

3 Weathered sandstone fragments

50/1"


4

15

Subangular gravel (from cuttings), maximum 1 inch 5

20

SILTY CLAY (CL), olive brown, hard, moist, low plasticity, 10% fine-grained sand

6 25

7

25

8

POORLY GRADED GRAVEL WITH SILT (GP-GM), gray, dense, moist, subangular to subrounded gravel, maximum size 1 inch

30/1"

23.5

4.25*





POORLY GRADED GRAVEL WITH SILT (GP-GM), gray, dense, moist, subangular to subrounded gravel, maximum size 1 inch 9 30

10

35

11 SILTY SAND (SM), brown, very dense, damp, medium- to coarse-grained sand, with gravel, weak cementation, with rust staining 12


40 81/12"

8.3

84/12"

12.1

13

45

14

15 50

Grades to tan, fine- to medium-grained sand Boring terminated at approximately 51 feet. No groundwater encountered.





Plasticity Index

Plastic Limit

Liquid Limit

Blow Count/Foot

Water Level

DESCRIPTION

Log Symbol

Sample Type

Depth in Meters

Depth in Feet

Atterberg Limits





1

5

2

SANDY CLAY (CL), olive brown, stiff, moist, low to medium plasticity, 20% fines Expansion Index: 48.5 (low expansion potential); Resistance value: 10 SILTY CLAY (CL), light olive brown, hard, moist, low plasticity, trace fine-grained sand Increasing silt, trace rust staining, grades to tough, medium plasticity, less silt, olive-brown Soil corrosion: pH 7.97; minimum resistivity 0.99 ohm-cm (x1000); chloride 32.7 ppm; sulfate 134.6 ppm.




9

2.5* 4.5+*

12.6

18

75 4.5+*

SILTY SAND (SM), olive brown, very dense, moist, fine- to medium-grained sand, with gravel 85/9"

49

Grades to coarse-grained sand

10


Plasticity Index

Plastic Limit

Liquid Limit

Blow Count/Foot

Water Level

DESCRIPTION

Log Symbol

Sample Type

Depth in Meters

Depth in Feet

Atterberg Limits

3 Medium dense, fine- to medium grained sand, with gravel

23

24


4 SILTY CLAY WITH SAND (CL), brown, hard, moist, low plasticity, 20% fine-grained sand 15 62

26

16

10

4.5+*

12.3

5 Notably softer at 17 feet

20

6 Increasing silt and fine-grained sand, low plasticity 23

7

25

8

POORLY GRADED SAND WITH SILT (SP-SM), grayish brown, dense, moist, fine- to coarse-grained sand, trace gravel, well rounded sand

38

15.3

103.7 4.0*








Plasticity Index

Plastic Limit

Liquid Limit

Blow Count/Foot

Water Level

DESCRIPTION

Log Symbol

Sample Type

Depth in Meters

Depth in Feet

Atterberg Limits

SILTY SAND (SM), brown, medium dense, moist, fine- to medium-grained sand, 20% silt

9 30

POORLY GRADED SAND WITH GRAVEL (SP), gray, dense, moist, coarse-grained sand, 5% silt

47

Grades to medium dense, some rust staining

24

10

35

11

4.5+*

SANDY CLAY (CL), olive brown, hard, moist, fine-grained sand, with rust staining

12


40

Grades to with coarse-grained sand SILTY CLAY (CL), olive brown, medium stiff, moist, with rust staining, 10% fine-grained sand

1.75* 4.0*

20

13 SILTY SAND (SM), brown, medium dense, moist, fine- to coarse-grained sand, with gravel, 15% silt 45

14

23

5.4

40

14.4

Grades to fine-grained sand, 40% silt, trace clay

SANDY CLAY (CL), reddish brown, medium stiff, wet, fine- to medium-grained sand, trace gravel 15 50


0.75*






6.8

90.2




Plasticity Index

Plastic Limit

Liquid Limit

Blow Count/Foot

Water Level

DESCRIPTION

Log Symbol

Sample Type

Depth in Meters

Depth in Feet

Atterberg Limits

CLAYEY SAND (SC), brown, loose, moist, fine- to medium-grained sand, 35% fines Soil corrosion: pH 7.76; minimum resistivity 2.28 ohm-cm (x1000); chloride 17.3 ppm; sulfate 19.7 ppm. 1

5

SANDY SILT (ML), light brown, medium stiff, damp, fine- to medium-grained sand, trace vessicles

10

49

SILTY SAND (SM), light brown, loose, damp, fine- to medium-grained sand, 30% fines 2

10

8

7

9.1

3 7


4

SANDY CLAY (CL), brown, hard, moist, low plasticity, trace carbonates, 40% fine- to medium-grained sand

15 18

5

20

6 59

7

Gravel lense

25 31

8 Boring terminated at approximately 26.5 feet. No groundwater encountered.

10.8

4.5*

LOG OF BORING B-11A Geotechnical Exploration Panoche Valle Solar Farm San Benito County, California 8924.000.000




SILTY SAND (ML), light brown, medium stiff, damp, fine- to medium-grained sand, 25% silt

1 8

49

17

72

5

2

Gravel lense 10

3

SANDY CLAY (CL), brown, very stiff, moist, low plasticity







Plasticity Index

Plastic Limit

Liquid Limit

Blow Count/Foot

Water Level

DESCRIPTION

Log Symbol

Sample Type

Depth in Meters

Depth in Feet

Atterberg Limits





1

5

2

73/11"

With rust staining

3 87


4

15

Increasing clay, moist

32

Completely weathered, 1.5-inch diameter siltstone fragments, subrounded 2.5-inch diameter gravel

40

5

20

13.5

6

7

25

67


4.4



14


14


Plasticity Index

28

CLAYEY SAND WITH GRAVEL (SC), yellowish red, very dense, damp, 35% fines 63

10

Plastic Limit

Blow Count/Foot 9

Liquid Limit

SILTY CLAY WITH SAND (CL), reddish brown, very stiff, moist, low to medium plasticity, trace gravel, 15% medium- to coarse-grained sand

Water Level

DESCRIPTION

Log Symbol

Sample Type

Depth in Meters

Depth in Feet

Atterberg Limits

2.25*





SILTY SAND (SM), brown, loose, moist, medium- to coarse-grained sand, with gravel, 25% fines 12

5.3

1 Grades to 15% fines, fine- to coarse-grained sand

13

3.5

CLAYEY SAND (SC), light brown, medium dense, damp, fine-grained sand, 40% fines

5

2

POORLY GRADED SAND WITH GRAVEL (SP), light brown, dense, damp, medium- to coarse-grained sand

66

SILTY SAND WITH GRAVEL (SM), light olive, dense, damp, fine- to coarse-grained sand 10

3 44


4

15

Grades to fine-grained sand, dark reddish-brown, trace gravel

32

5

CLAYEY SAND (SC), light brown, very dense, damp, fine- to coarse-grained sand, with gravel 20

6 72

7

25 76/12"


17





Plasticity Index

Plastic Limit

Liquid Limit

Blow Count/Foot

Water Level

DESCRIPTION

Log Symbol

Sample Type

Depth in Meters

Depth in Feet

Atterberg Limits








Plasticity Index

Plastic Limit

Liquid Limit

Blow Count/Foot

Water Level

DESCRIPTION

Log Symbol

Sample Type

Depth in Meters

Depth in Feet

Atterberg Limits

SILTY CLAY (CL), dark brown, very stiff, moist, medium plasticity, trace fine-grained sand 28

Grades to hard, with carbonates

1

Grades to dark yellowish-brown, damp, 20% sand and gravel

2

58

3

71

POORLY GRADED SAND WITH SILT AND GRAVEL (SP-SM), yellowish brown, medium dense, damp, fine- to coarse-grained sand, 30% gravel, 8% fines 27

SILTY SAND (SM), light reddish brown, medium dense, damp, fine- to medium-grained sand, 40% silt


4

15

Grades to with coarse-grained sand and gravel

34

Grades to trace coarse-grained sand and gravel, trace carbonates

48

5

20

3.0* 4.5+*

Soil corrosion: pH 7.65 minimum resistivity 1.13 ohm-cm (x1000); chloride 176.3 ppm; sulfate 653.7 ppm.

5

10

16.2

6

7

25

8

Grades to with coarse-grained sand and gravel, trace clay, 20% fines Boring terminated at approximately 26.5 feet. No groundwater encountered.

59

7.6 4.5+*








Plasticity Index

Plastic Limit

Liquid Limit

Blow Count/Foot

Water Level

DESCRIPTION

Log Symbol

Sample Type

Depth in Meters

Depth in Feet

Atterberg Limits

SANDY SILT (ML), dark brown, stiff, moist, fine-grained sand, trace rootlets 5

1.5* 4.0*

Grades to yellowish-brown, no rootlets, very stiff

1

SILTY CLAY (CL), yellowish brown, very soft, moist, low plasticity, trace carbonates, 10% fine-grained sand, trace vessicles

14

3.5*

5

2

10

25% fine-grained sand, vessicles continue

15

7.2

97

4.5+*

3 19

8.4

4.5+*

7.8

4.5+*


4

15 45

5

20

6 Increasing carbonates, weak cementation Boring terminated at approximately 21.5 feet. No groundwater encountered.

75

4.5*








Plasticity Index

Plastic Limit

Liquid Limit

Blow Count/Foot

Water Level

DESCRIPTION

Log Symbol

Sample Type

Depth in Meters

Depth in Feet

Atterberg Limits

SANDY CLAY (CL), dark brown, very stiff, moist, low plasticity, trace rootlets, 40% fine-grained sand 8

Hard, no rootlets

1 Trace vessicles, 45% fine-grained sand, damp

10

14.6

2.25* 4.5*

8.3 3.75* 4.5+*

5

2

10

12

10

78.7

4.5+*

3 Vessicles continue, increase carbonates, medium plasticity

19

Trace gravel

21

Grades to moist

36

4.5+*


4

15 4.5+*

5

20

6

24

7


4.5*





1

SILTY CLAY WITH SAND (CL), dark yellowish brown, very stiff, moist, trace gravel Grades to damp, light yellowish-brown, trace vessicles and carbonate Soil corrosion: pH 7.51; minimum resistivity 1.96 ohm-cm (x1000); chloride 58.7 ppm; sulfate 8.5 ppm. Cobble encountered at 2.5 feet maximum dimension

23

22

Grades to with gravel (2-inch maximum diameter)





Plasticity Index

Plastic Limit

Liquid Limit

Blow Count/Foot

Water Level

DESCRIPTION

Log Symbol

Sample Type

Depth in Meters

Depth in Feet

Atterberg Limits

3.5* 4.5+*

7.3

3.5*

5

2

10

With carbonates, trace fine-grained sand, no gravel

32

Grades to low plasticity

29

Trace gravel

53

4.5+*

3 7.4

4.5+*


4

15

5

SILTY SAND (SM), yellowish brown, dense, damp, fine- to medium-grained sand, trace carbonates 20

6 40


4.5+*








Plasticity Index

Plastic Limit

Liquid Limit

Blow Count/Foot

Water Level

DESCRIPTION

Log Symbol

Sample Type

Depth in Meters

Depth in Feet

Atterberg Limits

SILTY SAND (SM), brown, loose, moist, fine- to medium-grained sand, 30% fines 8

SANDY CLAY (CH), brown, hard, moist, low plasticity, 35% fine- to medium-grained sand

4.5*

1 Grades to medium plasticity, with carbonates, weak cementation, trace vessicles, yellowish-brown

76/12"

54

22

32

12.6

5

2

10

CLAYEY SAND (SC), yellowish brown, very dense, damp, fineto medium-grained sand, trace carbonates, 30% fines

80/9"

Trace gravel

50/6"

Abundant carbonate, moderate cementation Boring terminated at approximately 15.5 feet. No groundwater encountered.

63/6"

3


4

15

7.9

4.5+*








Plasticity Index

Plastic Limit

Liquid Limit

Blow Count/Foot

Water Level

DESCRIPTION

Log Symbol

Sample Type

Depth in Meters

Depth in Feet

Atterberg Limits

SILTY CLAY (CL), dark brown, stiff, moist, low plasticity, trace fine-grained sand 14

Grades to damp, brown

21.9 2.0*

1 Hard, trace vessicles

24

Grades to medium plasticity

18

Grades to moist

23

Grades to low plasticity

19

Increasing carbonates

13

12.2

84.1

2.25* 4.5+*

5

2

10

4.5+*

3 4.5+*


4

15 4.5+*

5

20

6

7

25 25

8 Boring terminated at approximately 26.5 feet. No groundwater encountered.

4.5*








Plasticity Index

Plastic Limit

Liquid Limit

Blow Count/Foot

Water Level

DESCRIPTION

Log Symbol

Sample Type

Depth in Meters

Depth in Feet

Atterberg Limits

SILTY SAND (SM), brown, very loose, moist, fine- to medium-grained sand, 25% fines 3

1

SILTY CLAY WITH SAND (CL), yellowish brown, hard, damp, trace carbonates, 15% fine- to medium grained sand Soil corrosion: pH 7.67; minimum resistivity 1.02 ohm-cm (x1000); chloride 25.3 ppm; sulfate 86.8 ppm.

17

4.5+*

5

2

10

CLAY (CH), yellowish brown, hard, damp, high plasticity, with carbonates, 5% find-grained sand 79

23

30

14.7

4.5+*

3 15% fine- to medium-grained sand

4 LOG - GEOTECHNICAL 8924.000.000 EXPLORATION DATABASE.GPJ ENGEO INC.GDT 3/26/10

53

15

82/9" 4.5+*

SILTY CLAY WITH SAND (CL), yellowish brown, hard, damp, low plasticity, 15% fine- to medium grained sand

Weak cementation, abundant carbonates

57/6"

5

20

6 Very stiff, mottled with olive-brown, medium plasticity, moist, 15% fine-grained sand

25

7 SILTY SAND (SM), light brown, dense, damp, fine- to medium-grained sand, trace gravel, 25% fines 25 38

8

19.2

3.25*








Plasticity Index

Plastic Limit

Liquid Limit

Blow Count/Foot

Water Level

DESCRIPTION

Log Symbol

Sample Type

Depth in Meters

Depth in Feet

Atterberg Limits

SILTY SAND (SM), light brown, dense, damp, fine- to medium-grained sand, trace gravel, 25% fines

9 30

Grades to with silty clay lenses, olive-brown with rust staining

68

10

35

11

Increasing moisture 12


40

Gravel lense, perched groundwater Grades to 45% fines Grades to 12% fines, trace, gravel, very dense

80/12"

13

45

14

SANDY CLAY (CL), olive brown, hard, moist, medium plasticity, 35% sand, with rust staining

15 50 56

Boring terminated at approximately 51.5 feet. Perched groundwater encountered at approximately 39 feet.

4.5*








Plasticity Index

Plastic Limit

Liquid Limit

Blow Count/Foot

Water Level

DESCRIPTION

Log Symbol

Sample Type

Depth in Meters

Depth in Feet

Atterberg Limits

SILTY CLAY (CL), dark brown, very stiff, moist, trace fine-grained sand 13

SILTY SAND (SM), dark brown, loose, moist, fine- to medium-grained sand

3.75*

1 8

43

5

2

10

SILTY CLAY (CL), yellowish brown, hard, damp, low plasticity, trace sand

14

Grades to medium plasticity, trace vessicles, trace carbonates

18

4.5+*

3 4.5+*


4

15

Mottled reddish-brown and olive-brown

80/12" 4.5+*

5

20

6 Grades to low plasticity Boring terminated at approximately 21.5 feet. No groundwater encountered.

62

4.5+*








Plasticity Index

Plastic Limit

Liquid Limit

Blow Count/Foot

Water Level

DESCRIPTION

Log Symbol

Sample Type

Depth in Meters

Depth in Feet

Atterberg Limits

SANDY SILT (ML), dark brown, stiff, moist, fine- to medium-grained sand

1

Grades to with 15% fine- to medium-grained sand

14

SILTY CLAY (CL), yellowish brown, hard, moist, medium plasticity, trace carbonates

13

2.0* 4.5+*

5

2

16

9

92.1

4.5+*

12

10

3


4

15

Grades to very stiff 5


16

3.25*

APPENDIX B LABORATORY TEST DATA Liquid and Plastic Limits Test Report Unconfined Compression Test Particle Size Distribution Report R-Value Test Reports Analytical Results of Soil Corrosion Thermal Analysis

A P P E N D I X B

#200

#140

#100

#60

#40

#30

#20

#10

#4

3/8 in.

½ in.

¾ in.

1 in.

1½ in.

2 in.

3 in.

6 in.

Particle Size Distribution Report 100 90

80

PERCENT FINER

70

60

50

40

30

20

10 0 100

10

1

0.1

0.01

0.001

GRAIN SIZE - mm. % Gravel Coarse Fine

% +3"

0.0

19.3

Coarse

20.2

13.3

PERCENT

SPEC.*

PASS?

SIZE

FINER

PERCENT

(X=NO)

1-1/2" 1" 3/4" 1/2" 3/8" #4 #8 #16 #30 #50 #100 #200

100.0 91.0 80.7 74.0 70.3 60.5 49.4 41.8 37.6 33.0 27.4 23.4

SIEVE

% Sand Medium

11.7

% Fines Fine

Silt

12.1

Clay

23.4 Soil Description

Clayey Sand

PL= D85= 21.5585 D30= 0.2091 Cu= USCS=

Atterberg Limits LL=

PI=

Coefficients D60= 4.5934 D50= 2.4582 D15= D10= Cc = Classification AASHTO= Remarks

* (no specification provided) Sample No.: [email protected]' Source of Sample: GEX Location: Panoche Valley Solar Farm

ENGEO, Inc. Rocklin, CA

Date: Elev./Depth: 3.0'

Client: Solargen Energy Inc. Project: Panoche Valley Solar Farm Project No: 8924.000.000

Figure

#200

#140

#100

#60

#40

#30

#20

#10

#4

3/8 in.

½ in.

¾ in.

1 in.

1½ in.

2 in.

3 in.

6 in.


80

PERCENT FINER

70

60

50

40

30

20

10 0 100

10

1

0.1

0.01

0.001


% +3"

0.0

0.0

Coarse

0.0

0.1

PERCENT

SPEC.*

PASS?

SIZE

FINER

PERCENT

(X=NO)

1-1/2" 1" 3/4" 1/2" 3/8" #4 #8 #16 #30 #50 #100 #200

100.0 100.0 100.0 100.0 100.0 100.0 99.9 99.8 99.4 94.1 72.3 47.1

SIEVE

% Sand Medium

1.5

% Fines Fine

Silt

51.3

Clay


Silty Sand

PL= D85= 0.2143 D30= Cu= USCS=


PI=






Figure

#200

#140

#100

#60

#40

#30

#20

#10

#4

3/8 in.

½ in.

¾ in.

1 in.

1½ in.

2 in.

3 in.

6 in.


80

PERCENT FINER

70

60

50

40

30

20

10 0 100

10

1

0.1

0.01

0.001


% +3"

0.0

0.0

Coarse

2.4

1.4

PERCENT

SPEC.*

PASS?

SIZE

FINER

PERCENT

(X=NO)

1-1/2" 1" 3/4" 1/2" 3/8" #4 #8 #16 #30 #50 #100 #200

100.0 100.0 100.0 100.0 100.0 97.6 96.4 95.7 94.7 89.2 71.8 51.0

SIEVE

% Sand Medium

3.0

% Fines Fine

Silt

42.2

Clay


Silty Sand

PL= D85= 0.2435 D30= Cu= USCS=


PI=

Coefficients D60= 0.1010 D50= D15= D10= Cc = Classification AASHTO= Remarks





Figure

#200

#140

#100

#60

#40

#30

#20

#10

#4

3/8 in.

½ in.

¾ in.

1 in.

1½ in.

2 in.

3 in.

6 in.


80

PERCENT FINER

70

60

50

40

30

20

10 0 100

10

1

0.1

0.01

0.001


% +3"

0.0

0.0

Coarse

11.4

7.2

PERCENT

SPEC.*

PASS?

SIZE

FINER

PERCENT

(X=NO)

1-1/2" 1" 3/4" 1/2" 3/8" #4 #8 #16 #30 #50 #100 #200

100.0 100.0 100.0 97.3 93.9 88.6 82.8 77.4 72.3 65.9 57.1 48.5

SIEVE

% Sand Medium

12.0

% Fines Fine

Silt

20.9

Clay


Silty Sand w/Gravel

PL= D85= 3.0586 D30= Cu= USCS=


PI=






Figure

#200

#140

#100

#60

#40

#30

#20

#10

#4

3/8 in.

½ in.

¾ in.

1 in.

1½ in.

2 in.

3 in.

6 in.


80

PERCENT FINER

70

60

50

40

30

20

10 0 100

10

1

0.1

0.01

0.001


% +3"

0.0

0.0

Coarse

10.3

15.2

PERCENT

SPEC.*

PASS?

SIZE

FINER

PERCENT

(X=NO)

1-1/2" 1" 3/4" 1/2" 3/8" #4 #8 #16 #30 #50 #100 #200

100.0 100.0 100.0 100.0 93.7 89.7 77.8 64.2 49.5 38.4 29.8 22.8

SIEVE

% Sand Medium

31.1

% Fines Fine

Silt

20.6

Clay


Silty Sand w/Gavel

PL= D85= 3.3678 D30= 0.1527 Cu= USCS=


PI=






Figure

#200

#140

#100

#60

#40

#30

#20

#10

#4

3/8 in.

½ in.

¾ in.

1 in.

1½ in.

2 in.

3 in.

6 in.


80

PERCENT FINER

70

60

50

40

30

20

10 0 100

10

1

0.1

0.01

0.001


% +3"

0.0

0.0

Coarse

1.1

0.5

PERCENT

SPEC.*

PASS?

SIZE

FINER

PERCENT

(X=NO)

1-1/2" 1" 3/4" 1/2" 3/8" #4 #8 #16 #30 #50 #100 #200

100.0 100.0 100.0 100.0 100.0 98.9 98.5 98.0 97.0 93.2 82.3 49.0

SIEVE

% Sand Medium

2.9

% Fines Fine

Silt

46.5

Clay


Silty Sand

PL= D85= 0.1644 D30= Cu= USCS=


PI=






Figure

#200

#140

#100

#60

#40

#30

#20

#10

#4

3/8 in.

½ in.

¾ in.

1 in.

1½ in.

2 in.

3 in.

6 in.


80

PERCENT FINER

70

60

50

40

30

20

10 0 100

10

1

0.1

0.01

0.001


% +3"

0.0

0.0

Coarse

0.0

0.1

PERCENT

SPEC.*

PASS?

SIZE

FINER

PERCENT

(X=NO)

1-1/2" 1" 3/4" 1/2" 3/8" #4 #8 #16 #30 #50 #100 #200

100.0 100.0 100.0 100.0 100.0 100.0 99.9 99.8 99.5 97.7 88.0 72.1

SIEVE

% Sand Medium

0.7

% Fines Fine

Silt

27.1

Clay


Sandy Clay

PL= D85= 0.1297 D30= Cu= USCS= SP


PI=

Coefficients D60= D50= D15= D10= Cc = Classification AASHTO= Remarks





Figure

#200

#140

#100

#60

#40

#30

#20

#10

#4

3/8 in.

½ in.

¾ in.

1 in.

1½ in.

2 in.

3 in.

6 in.


80

PERCENT FINER

70

60

50

40

30

20

10 0 100

10

1

0.1

0.01

0.001


% +3"

0.0

0.0

Coarse

1.0

0.9

PERCENT

SPEC.*

PASS?

SIZE

FINER

PERCENT

(X=NO)

1-1/2" 1" 3/4" 1/2" 3/8" #4 #8 #16 #30 #50 #100 #200

100.0 100.0 100.0 100.0 100.0 99.0 98.2 97.5 95.6 87.6 75.2 49.0

SIEVE

% Sand Medium

5.9

% Fines Fine

Silt

43.2

Clay


Silty Sand

PL= D85= 0.2469 D30= Cu= USCS=


PI=






Figure

#200

#140

#100

#60

#40

#30

#20

#10

#4

3/8 in.

½ in.

¾ in.

1 in.

1½ in.

2 in.

3 in.

6 in.


80

PERCENT FINER

70

60

50

40

30

20

10 0 100

10

1

0.1

0.01

0.001


% +3"

0.0

11.7

Coarse

20.8

13.5

PERCENT

SPEC.*

PASS?

SIZE

FINER

PERCENT

(X=NO)

1-1/2" 1" 3/4" 1/2" 3/8" #4 #8 #16 #30 #50 #100 #200

100.0 90.8 88.3 85.4 78.0 67.5 56.6 45.9 36.6 27.6 20.7 16.8

SIEVE

% Sand Medium

22.0

% Fines Fine

Silt

15.2

Clay


Silty Sand w/Gravel

PL= D85= 12.4611 D30= 0.3627 Cu= USCS=


PI=






Figure

#200

#140

#100

#60

#40

#30

#20

#10

#4

3/8 in.

½ in.

¾ in.

1 in.

1½ in.

2 in.

3 in.

6 in.


80

PERCENT FINER

70

60

50

40

30

20

10 0 100

10

1

0.1

0.01

0.001


% +3"

0.0

0.0

Coarse

0.5

0.6

PERCENT

SPEC.*

PASS?

SIZE

FINER

PERCENT

(X=NO)

1-1/2" 1" 3/4" 1/2" 3/8" #4 #8 #16 #30 #50 #100 #200

100.0 100.0 100.0 100.0 100.0 99.5 99.0 98.7 98.3 90.8 65.1 43.1

SIEVE

% Sand Medium

2.3

% Fines Fine

Silt

53.5

Clay


Silty Sand

PL= D85= 0.2487 D30= Cu= USCS=


PI=






Figure

Unconfined Compression Test ASTM Test Method D2166 1400

1200

Axial pressure (psf)

1000

800

600

400

200

0 0

2

4

6

8

10

12

Percent Strain

Unconfined Compressive Strength:

1250 psi

0.6 tsf

Sample Description: (ML) Brown Sandy Silt

Initial Diameter: Initial Height: Strain Rate: Total Strain:

EN GEO INCORPORATED

2.42 4.41 1.15 2.49

in. in. %/min %

Sample Number: Boring Number: Dry Unit Weight: Moisture Content: Depth of Sample:

Panoche Valley Solar Farm

Panoche Valley, CA

B4-6.5 B4 89.8 pcf 7.4 % 6.5 ft.

Job No.: 8924.000.000 Sample B4-6.5 Number: Date:

3/11/2010

Figure No.


1200


1000

800

600

400

200

0 0

2

4

6

8

10

12

Percent Strain


1160 psi

0.6 tsf

Sample Description: (ML) Brown Sandy Silt


EN GEO INCORPORATED

2.42 5.50 0.72 4.18

in. in. %/min %



Panoche Valley, CA

B9-1 B9 98.4 15.2 1.0

pcf % ft.

Job No.: 8924.000.000 Sample B9-1 Number: Date:

3/11/2010

Figure No.



2000

1500

1000

500

0 0

2

4

6

8

10

12

Percent Strain


2200 psi

1.1 tsf

Sample Description: (ML) Dark Brown Sandy Silt


EN GEO INCORPORATED

2.42 4.20 1.27 5.71

in. in. %/min %



Panoche Valley, CA

B15-1.5 B15 99.7 pcf 14.3 % 1.5 ft.

Job 8924.000.000 No.: Sample B15-1.5 Number: Date:

3/19/2010

Figure No.

Unconfined Compression Test ASTM Test Method D2166 2000 1800 1600


1400 1200 1000 800 600 400 200 0 0

2

4

6

8

10

12

Percent Strain


1750 psi

0.9 tsf

Sample Description: (CL) Dark Brown Sandy Clay


EN GEO INCORPORATED

2.42 4.95 2.00 3.64

in. in. %/min %



Panoche Valley, CA

B16-4 B16 91.7 pcf 7.3 % 4.0 ft.

Job 8924.000.000 No.: Sample B16-4 Number: Date:

3/19/2010

Figure No.

LIQUID AND PLASTIC LIMITS TEST REPORT 60

O H

Dashed line indicates the approximate upper limit boundary for natural soils

CH

or

50

O

L

30

or

20

CL

PLASTICITY INDEX

40

10 CL-ML

4 7

0

0

10

ML or OL

20

30

40

MH or OH 50 60 LIQUID LIMIT

70

80

90

100

110

SOIL DATA SYMBOL

NATURAL WATER CONTENT (%)

PLASTIC LIMIT (%)

LIQUID LIMIT (%)

PLASTICITY INDEX (%)

1.5'

10.3

13

25

12

CL

[email protected]'

11.0'

7.3

19

29

10

CL

GEX

[email protected]'

1.5'

12.6

18

35

17

CL

GEX

[email protected]'

1.5'

19.1

18

32

14

CL

GEX

[email protected]'

16.0'

12.3

16

26

10

CL

SOURCE

SAMPLE NO.

DEPTH

GEX

[email protected]'

GEX

ENGEO, Inc.

Client: Solargen Energy Inc. Project: Panoche Valley Solar Farm

Rocklin, CA

Project No.: 8924.000.000

Figure

USCS

LIQUID AND PLASTIC LIMITS TEST REPORT 60

Dashed line indicates the approximate upper limit boundary for natural soils 50

PLASTICITY INDEX

CH

OH or

40

30

L rO o CL

20

10 CL-ML

ML or OL

4 7

MH or OH

0 0

10

20

30

40

50 60 LIQUID LIMIT

70

80

90

100

SOIL DATA NATURAL WATER CONTENT (%)

PLASTIC LIMIT (%)

LIQUID LIMIT (%)

SOURCE

SAMPLE NO.

DEPTH

GEX

[email protected]'

1.5'

13.5

14

28

14

0.0

CL

GEX

[email protected]'

4.0'

12.6

22

54

32

-0.3

CH

GEX

[email protected]'

7.0'

14.7

23

53

30

-0.3

CH


PLASTICITY LIQUIDITY INDEX INDEX (%)

Client: Solargen Energy Inc. Project: Panoche Valley Solar Farm Project No.: 8924.000.000

Figure

USCS

110

R VALUE TEST REPORT CAL-301 90 85 80 75 70 65 60 55

45

R-Value

50

40 35 30 25 20 15 10 5 0 900

800

700

600

500

400

300

200

100

0

Exudation Pressure (psi)

Date: Project Name: Project Number: Sample: Description:

3/19/10 Panoche Valley Solar Farm 8924.000.000 B3 (0-1') (CL) Brown Sandy Clay w/gravel

Specimen Exudation Pressure, p.s.i. Expansion dial (.0001") Expansion Pressure, p.s.f. Resistance Value, "R" % Moisture at Test Dry Density at Test, p.c.f. "R" Value at 300 p.s.i., Exudation Pressure

A 743 5 22 38 8.6 140.3

B 311 0 0 8 10.8 134.4

7

C 208 0 0 0 12.1 131.2

R VALUE TEST REPORT CAL-301 90 85 80 75 70 65 60 55

45

R-Value

50

40 35 30 25 20 15 10 5 0 900

800

700

600

500

400

300

200

100

0

Exudation Pressure (psi)

Date: Project Name: Project Number: Sample: Description:

3/19/10 Panoche Valley Solar Farm 8924.000.000 B10 (0-1') (CL) Brown Sandy Clay

Specimen Exudation Pressure, p.s.i. Expansion dial (.0001") Expansion Pressure, p.s.f. Resistance Value, "R" % Moisture at Test Dry Density at Test, p.c.f. "R" Value at 300 p.s.i., Exudation Pressure

A 795 178 771 48 15.1 117.9

B 677 120 520 33 16.9 111.6

10

C 287 0 0 10 20.6 104.4

GeothermUSA http://www.geotherm.net

6354 Clark Ave. Dublin, CA 94568 Tel: 925-999-9232 Fax: 925-999-8837 [email protected]

March 20, 2010

ENGEO 2213 Plaza Drive Rocklin, CA 95765 ATTN: Dana Tolar Re: Thermal Analysis of Native Soil Samples Panoche Valley Solar Project – Job No. 8924.000.000

The following is the report of thermal dryout characterization tests conducted on the two (2) native soil samples from the referenced project. These were undisturbed tube samples.

Test Procedure and Equipment: The tests included the measurement of moisture content, density and thermal dryout characterization (thermal resistivity as a function of moisture content). A laboratory type thermal probe was installed central and vertical in each samples and a series of measurements were made in stages, with moisture contents ranging from the ‘natural’ to the totally dry condition. The tests were conducted in accordance with the IEEE standard. The results are tabulated below and the thermal dryout curves are presented in Figure 1.

Sample ID, Description, Moisture Content, Dry Density and Thermal Resistivity Thermal Resistivity (°C-cm/W) Wet Dry

Location #

Depth (ft)

Visual Description

B-3

4

Clayey Sand with gravel

79

B-10

6.5

Silty Sand with trace gravel

88

Moisture Content (%)

Dry Density (pcf)

147

6

112

189

6

109

COOL SOLUTIONS FOR UNDERGROUND POWER CABLES THERMAL SURVEYS, CORRECTIVE BACKFILLS & INSTRUMENTATION

Serving the electric power industry since 1978

GeothermUSA Comments The thermal characteristic depicted in Figure 1 will apply only if the soils are at dry densities of not less than the test values.

Please contact us if you have any questions, wish to discuss any part of this report or if we can be of further assistance.

Geotherm USA

Nimesh Patel

Please Note: All samples will be disposed of after 5 days from date of report

2

GeothermUSA

3

GeothermUSA http://www.geotherm.net

6354 Clark Ave. Dublin, CA 94568 Tel: 925-999-9232 Fax: 925-999-8837 [email protected]

March 24, 2010

ENGEO 2213 Plaza Drive Rocklin, CA 95765 Attn: Dana Tolar Re: Thermal Analysis of Native Soil Sample Panoche Valley Solar Project – Job No. 8924.000.000

The following is the report of thermal dryout characterization tests conducted on the one (1) native soil sample from the referenced project. This was an undisturbed tube sample.

Test Procedure and Equipment: The tests included the measurement of moisture content, density and thermal dryout characterization (thermal resistivity as a function of moisture content). A laboratory type thermal probe was installed central and vertical in the sample and a series of measurements were made in stages, with moisture contents ranging from the ‘natural’ to the totally dry condition. The tests were conducted in accordance with the IEEE standard. The results are tabulated below and the thermal dryout curve is presented in Figure 1.

Sample ID, Description, Moisture Content, Dry Density and Thermal Resistivity Location #

Depth (ft)

Visual Description

B-15

4

Silty CLAY with trace fine sand

Thermal Resistivity (°C-cm/W) Wet Dry 151

288

Moisture Content (%)

Dry Density (pcf)

7.3

94

COOL SOLUTIONS FOR UNDERGROUND POWER CABLES THERMAL SURVEYS, CORRECTIVE BACKFILLS & INSTRUMENTATION

Serving the electric power industry since 1978

GeothermUSA Comments The thermal characteristic depicted in Figure 1 will apply for the soil at dry density of not less than the test values.

Please contact us if you have any questions, wish to discuss any part of this report or if we can be of further assistance.

Geotherm USA

Nimesh Patel

Please Note: All samples will be disposed of after 5 days from date of report

2

GeothermUSA

3

APPENDIX C NORCAL Geophysical Electrical Resistivity Test Data

A P P E N D I X C

geotechnical report - San Benito County

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