AttachmentE_CI5585_GeotechReports.pdf

ATTACHMENT E – GEOTECH REPORTS

MSC EXPANSION (2009) (69 PAGES)

SOLAR CARPORT (2016) (85 PAGES)

SOLAR CARPORT (2021) (40 PAGES)

CI 5585 – MUNICIPAL SERVICE CENTER MICROGRID AND BACKUP

POWER

GEOTECHNICAL ENGINEERING STUDY

Municipal Service Center

1993 Rancho Conejo Boulevard Thousand Oaks, CA 91320

February 25, 2021

Prepared for:

SiteLogiQ

Prepared By:

Geo-Engineering Solutions, Inc.

2570 San Ramon Valley Blvd, Suite #A102 San Ramon, California 94583

Project No. 72-1304

2570 San Ramon Valley Blvd., Suite A102 San Ramon, CA | 925-433-0450

February 25, 2021

Attention: Mr. Nathan Gustus, Project Manager

Subject: Geotechnical Engineering Study Municipal Service Center 1993 Rancho Conejo Boulevard Thousand Oaks, California 91320

Geo-Eng Project No. 72-1304

Dear Mr. Gustus:

In accordance with your authorization, Geo-Engineering Solutions, Inc. (Geo-Eng) has completed a Geotechnical Engineering Study at the Municipal Service Center located at 1993 Rancho Conejo Boulevard in Thousand Oaks, California. This report has been prepared in accordance with the requirements set forth in the 2019 California Building Code. Transmitted herewith are the results of our findings, conclusions, and recommendations for the design and installation of the proposed carport solar panels at the site. In general, the proposed development at the site are geotechnically and geologically feasible provided the recommendations of this report are implemented in the design and construction of the project.

Should you or members of the design team have questions or need additional information, please contact Mr. Haddad at 925-215-7789, nhaddad@geo-eng.net or Mr. Swenson at 925-433-0450, eswenson@geo-eng.net.

We greatly appreciate the opportunity to provide our services and to be involved in the design of this project.

Sincerely, GEO-ENGINEERING SOLUTIONS, INC.

Nicolas B. Haddad, PE Eric J. Swenson, GE, CEG Senior Geotechnical Engineer Principal Engineer and Geologist mailto:nhaddad@geo-eng.net mailto:eswenson@geo-eng.net

Geotechnical Engineering Study Municipal Service Center, Thousand Oaks

TABLE OF CONTENTS

1.0 INTRODUCTION

1.1 Purpose and Scope

1.2 Site Description

1.3 Proposed Development

2.0 PROCEDURES AND RESULTS

2.1 Literature Review

2.2 Field Exploration

2.3 Laboratory Testing

3.0 GEOLOGY AND SEISMICITY

3.1 Geologic Setting

3.2 Seismic Setting

4.0 SUBSURFACE CONDITIONS

4.1 Subsurface Soil Conditions

4.2 Groundwater

4.3 Corrosion Testing

5.0 GEOLOGIC HAZARDS

5.1 Seismic Induced Hazards

5.2 Expansive Soils

5.2 Consolidation Settlement

6.0 GEOTECHNICAL ENGINEERING CONCLUSIONS AND RECOMMENDATIONS

6.1 Conclusions

6.2 Seismic Parameters

6.3 Site Grading

6.4 Foundations Recommendations

6.5 Temporary Excavation Slopes

6.6 Utility Trench Construction

6.7 Validity of Report

7.0 LIMITATIONS AND UNIFORMITY OF CONDITIONS

8.0 REFERENCES

TABLE OF CONTENTS (cont’d.)

FIGURES

Figure 1 – Site Vicinity Map Figure 2 – Site Development Plan Figure 3 – Site Map and Boring Locations Figure 4 – Site Vicinity Geologic Map Figure 5 – Regional Fault Map

APPENDIX A

FIELD EXPLORATION

Boring Logs

APPENDIX B

LABORATORY TEST RESULTS

Atterberg Limit Results Grain Size Distribution Corrosivity Test Summary

1.0 INTRODUCTION

1.1 Purpose and Scope

The purpose of our work was to prepare a Geotechnical Engineering evaluation of the subsurface conditions at the site and prepare geotechnical recommendations for the proposed development. We have provided specific recommendations regarding suitability and geotechnical concerns relative to the proposed structural design.

The scope of this evaluation included the review of previous field explorations and laboratory testing conducted at the site, and preparation of this report. The conclusions and recommendations presented in this report are based on prudent engineering judgment and experience. This study did not include an in-depth assessment of potentially toxic or hazardous materials that may be present on or beneath the site.

1.2 Site Description

The proposed improvement project is located at the Municipal Service Center, 1993 Rancho Conejo Boulevard, Thousand Oaks, California, Figure 1 – Site Vicinity Map. The Municipal Service Center is bordered by undeveloped lands. The site consists of several buildings and parking lots. The site has relatively flat topography, with approximate elevations on the order of +634 based off Google Earth elevations.

1.3 Proposed Development

We understand that, based on information provided that the planned development project, as shown on Figure

2, Site Development Plan, will consist of the installation of new carport solar panel structures in the parking lot of the site. It is assumed there will be other associated site improvements such as minor grading and utilities.

2.0 PROCEDURES AND RESULTS

2.1 Literature Review

Pertinent geologic and geotechnical literature pertaining to the site area, and previous geotechnical studies performed by others for projects in the site vicinity were reviewed. These included United States Geological Survey

(USGS), California Geological Survey (CGS), other online resources, and other applicable government and private publications and maps, as included in the References section.

2.2 Field Exploration

A total of 3 borings were drilled at the site on February 2, 2021 at the approximate locations shown on Figure 3, Site Map and Boring Locations. The borings were drilled by Baja Exploration to a maximum depth of approximately

31.5 feet below existing ground surface in the vicinity of the proposed carport solar panel structures area, using a truck mounted B-57 drill rig equipped with eight-inch diameter hollow stem augers.

A Geo-Eng Staff Engineer visually classified the materials encountered in the borings according to the Unified Soil

Classification System as the borings were advanced. Relatively undisturbed soil samples were recovered at selected intervals using a three-inch outside diameter Modified California split spoon sampler containing six-inch long brass liners. A two-inch outside diameter Standard Penetration Test (SPT) sampler was also used to obtain

SPT blow counts and obtain disturbed soil samples. The samplers were driven by using a 140-pound safety hammer with an approximate 30-inch fall utilizing N-rods as necessary. Resistance to penetration was recorded as the number of hammer blows required to drive the sampler the final foot of an 18-inch drive. All the blow counts recorded using Modified California split spoon samplers in the field were converted to equivalent SPT blow counts using appropriate modification factors suggested by Burmister (1948), i.e., a factor of 0.65 assuming an inner diameter of 2.5 inches. Therefore, all blow counts shown on the final boring logs are either directly measured

(SPT sampler) or equivalent SPT (MC sampler) blow counts. Bulk samples were obtained in the upper few feet of the borings from the auger cuttings as needed.

The boring logs with descriptions of the various materials encountered in each boring, the penetration resistance values, and the laboratory test results are presented in Appendix A. The ground surface elevations indicated on the soil boring logs were determined using project survey data. Actual surface elevations at the boring locations may differ slightly than indicated. The locations of the borings should only be considered accurate to the degree implied by the means and methods used to define them.

2.3 Laboratory Testing

Laboratory tests were performed on selected samples to determine some of the physical and engineering properties of the subsurface soils. The results of the laboratory testing are presented on the boring logs, and included in Appendix B. The following soil tests were performed for this study:

Dry Density and Moisture Content (ASTM D2216 and ASTM 2937) – In-situ dry density and/or moisture tests were conducted on various samples to measure the in-place dry density and moisture content of the subsurface materials. These properties provide information to assist in evaluating the physical characteristics of the subsurface soils. Test results are shown on the boring logs.

Particle Size Analysis (Wet and Dry Sieve) and Fines Content (ASTM D422 and D1140) - Sieve analysis or fines content (minus No. 200 sieve) tests were conducted on a selected sample to measure the soil particle size distribution. This information is useful for the evaluation of liquefaction potential and characterizing the soil type according to USCS. Test results are presented on the boring logs or in Appendix B.

Atterberg Limits (ASTM D4318 and CT204) – Liquid Limit, Plastic Limit, and Plasticity Index are useful in the classification and characterization of the engineering properties of soil, helps evaluate the expansive characteristics of the soil, and for determining the soil type according to the USCS. The test results are presented on the applicable boring logs and in Appendix B.

Soil Corrosivity, Redox (ASTM D1498), pH (ASTM D4972), Resistivity (ASTM G57), Chloride (ASTM D4327), and

Sulfate (ASTM D4327) – Soil corrosivity testing was performed to determine the effects of constituents in the soil on buried steel and concrete. Water-soluble sulfate testing is required by the CBC and IBC. Test results are presented in Section 4.3 and in Appendix B.

3.0 GEOLOGY AND SEISMICITY

3.1 Geologic Setting

The site is located in the Transverse Range Geomorphic province of California. This province extends from the southern by the California Coast Ranges and to its south are the Peninsular Ranges. The Transverse Ranges are a series of east-west trending mountain ranges due to being along a transverse fault. There is a wide range of geologic units with sedimentary rock in the west, volcanic rock in the Santa Monica Mountains, and metamorphic rock in the central and eastern region.

3.2 Seismic Setting

The regional east-west orientation was caused by rotation of the bedrock units by the series of transverse faults trending northwest in the area. This structural deformation occurred during periods of tectonic activity that began in the Pliocene and continues today. This part of Southern California is dominated by the San Jacinto Fault which bounds the northern and eastern end of the Transverse Range as well as sub parallel faults extending through the geomorphic province including the Elsinore as well as other faults.

The subject property is in a seismically active region with the Elsinor fault approximately 20 miles to the northeast.

The site location relative to active and potentially active faults in the Thousand Oaks area is shown on Figure 5, Regional Fault Map.

4.0 SUBSURFACE CONDITIONS

Subsurface conditions below the project site were interpreted based on the results of the test borings performed for this study, as well as the results of our laboratory testing. Detailed descriptions of the various subsurface soil units encountered during subsurface explorations are described in the following paragraphs.

4.1 Subsurface Soil Conditions

During our subsurface exploration program, we investigated the subsurface soils and evaluated soil conditions to a maximum depth of 31.5 feet below ground surface for this study. Based on our observations the site generally appears to be underlain by a layer of very stiff gravelly clay in the upper 5 feet, underlain by a layer of medium dense clayey sand to a depth of around 10 feet below ground surface, underlain by a layer of very stiff sandy clay to a depth of around 30 feet below ground surface, underlain by a layer of highly weathered siltstone to the maximum depth explored of 31.5 feet below existing ground surface.

Soil samples of the near surface fine grained material from Boring B-2 at 4 feet below ground surface was tested for Atterberg Limits, with measured Liquid Limit (LL) of 50, Plastic Limit (PL) of 25, and corresponding Plasticity

Index (PI) of 25. Based on these test results the near surface soil would be considered to be of moderate to high plasticity and have a moderate to high expansion potential.

Additional details of the soils encountered in the exploratory borings are included in the boring logs presented in

Appendix A.

4.2 Groundwater

No groundwater was encountered during the subsurface exploration. We note that the borings may not have been left open for a sufficient period of time to establish equilibrium groundwater conditions. Groundwater levels can vary in response to time of year, variations in seasonal rainfall, tidal influence, well pumping, irrigation, and alterations to site drainage.

4.3 Corrosion Testing

A representative soil sample collected within the upper 5 feet of boring B-3 was tested to measure sulfate content, chloride content, redox potential, pH, resistivity, and presence of sulfides. Test results are included in Appendix B and are summarized on the following table.

Table 1: Summary of Corrosion Test Results

Soil Description Sample Depth (feet)

Sulfate (mg/kg)

Chloride (mg/kg)

Redox (mV)

Resistivity (ohm-cm) Sulfide pH

Reddish Brown Sandy CLAY 1-3 67 280 320 630 Negative 8.38

Water-soluble sulfate can affect the concrete mix design for concrete in contact with the ground, such as shallow foundations, piles, piers, and concrete slabs. Section 4.3 in American Concrete Institute (ACI) 318, as referenced by the CBC, provides the following evaluation criteria:

Table 2: Sulfate Evaluation Criteria

Sulfate Exposure

Water-Soluble Sulfate in Soil, Percentage by

Weight or (mg/kg)

Sulfate in Water, ppm

Cement Type

Max. Water Cementitious Ratio by Weight

Min. Unconfined Compressive Strength, psi

Negligible 0.00-0.10 (0-1,000)

0-150 NA NA NA

Moderate 0.10-0.20 (1,000-2,000)

150-1,500 II, IP (MS), IS

(MS)

0.50 4,000

Severe 0.20-2.00 (2,000-20,000)

1,500- 10,000

V 0.45 4,500

Very Severe Over 2.00 (20,000) Over 10,000 V plus pozzolan

0.45 4,500

The water-soluble sulfate content was measured to be about 67 mg/kg (ppm) or 0.0067% by dry weight in the soil sample, suggesting the site soil should have negligible impact on buried concrete structures at the site. However, it should be pointed out that the water-soluble sulfate concentrations can vary due to the addition of fertilizer, irrigation, and other possible development activities.

Table 4.4.1 in ACI 318 suggests use of mitigation measures to protect reinforcing steel from corrosion where chloride ion contents are above 0.06% by dry weight. The chloride content was measured to be 280 mg/kg (ppm) or 0.028% by dry weight in the soil sample. Therefore, the test result for chloride content does not suggest a corrosion hazard for mortar-coated steel and reinforced concrete structures due to high concentration of chloride.

In addition to sulfate and chloride contents described above, pH, oxidation reduction potential (Redox), and resistivity values were measured in the soil sample. For cast and ductile iron pipes, an evaluation was based on the 10-Point scaling method developed by the Cast Iron Pipe Research Association (CIPRA) and as detailed in

Appendix A of the American Water Works Association (AWWA) publication C-105 and shown on Table 3.

Table 3: Soil Test Evaluation Criteria (AWWA C-105)

Soil Characteristics Points Soil Characteristics Points Resistivity, ohm-cm, based on single probe or water-saturated soil box.

Redox Potential, mV

<700 10 >+100 0 700-1,000 8 +50 to +100 3.5 1,000-1,200 5 0 to 50 4 1,200-1,500 2 Negative 5 1,500-2,000 1 Sulfides >2,000 0 Positive 3.5 PH Trace 2 0-2 5 Negative 0 2-4 3 Moisture 4-6.5 0 Poor drainage, continuously wet 2 6.5-7.5 0 Fair drainage, generally moist 1 7.5-8.5 0 Good drainage, generally dry 0 >8.5 5

Assuming fair site drainage, the tested soil sample had a total score of 11 points, indicating a high corrosive rating.

When total points on the AWWA corrosivity scale are at least 10, the soil is classified as corrosive to cast and ductile iron pipe and use of cathodic corrosion protection is often recommended.

These results are preliminary and provide information only on the specific soil sampled and tested. Other soil at the site may be more or less corrosive. Providing a complete assessment of the corrosion potential of the site soils are not within our scope of work. For specific long-term corrosion control design recommendations, we recommend that a California-registered professional corrosion engineer evaluate the corrosion potential of the soil environment on buried concrete structures, steel pipe coated with cement-mortar, and ferrous metals.

5.0 GEOLOGIC HAZARDS

5.1 Seismic Induced Hazards

Seismic hazards resulting from the effects of an earthquake generally include ground shaking, liquefaction and dynamic settlement (densification), lateral spreading, fault ground rupture and fault creep, and tsunamis and seiches. The site is not necessarily impacted by these potential seismic hazards. Applicable potential seismic hazards are discussed and evaluated in the following sections in relation to the planned construction.

5.1.1 Ground Shaking

The site may experience some ground shaking from a major earthquake originating from many significant faults, including the San Andreas fault. Earthquake intensities vary throughout California depending upon the magnitude of the earthquake, the distance of the site from the causative fault, the type of materials underlying the site and other factors.

In addition to shaking of the structure, strong ground shaking can induce other related phenomena that may influence structures, such as liquefaction or dynamic densification settlement; adjacent seismic slope failure, lurching or lateral spreading, or seismically induced waves (tsunamis and seiches).

5.1.2 Liquefaction Induced Phenomena

Research and historical data indicate that soil liquefaction generally occurs in saturated, loose granular soil

(primarily fine to medium-grained, clean sand deposits) during or after strong seismic ground shaking and is typified by a loss of shear strength in the affected soil layer, thereby causing the soil to flow as a liquid. However, because of the higher inter-granular pressure of the soil at greater depths, the potential for liquefaction is generally limited to the upper 40 feet of the soil. Potential hazards associated with soil liquefaction below or near a structure include loss of foundation support, lateral spreading, sand boils, and areal and differential settlement.

Lateral spreading is lateral ground movement, with some vertical component, as a result of liquefaction. The soil literally rides on top of the liquefied layer. Lateral spreading can occur on relatively flat sites with slopes less than two percent under certain circumstances, generally when the liquefied layer is in relatively close proximity to an open, free slope face such as the bank of a creek channel. Lateral spreading can cause surficial ground tension cracking (i.e., lurch cracking) and settlement.

The site is not mapped within the local liquefaction hazard zone as defined by the Ventura County General Plan.

The soils encountered in the subsurface investigation included layers of medium dense clayey sand and very stiff sandy clay. These soils are expected to be generally less susceptible to liquefaction due to their relatively high fine-grain content and high density. Additionally, groundwater is anticipated to be at depths greater than 40 feet below the ground surface. Therefore, the potential for liquefaction of the site subsurface soils is judged to be low.

The site is not considered to be susceptible to lateral spreading due to the lack of a nearby free slope face.

Therefore, the potential for future seismic settlement due to lateral spreading is judged to be very low.

5.1.3 Dynamic Densification (Settlement)

Dynamic compaction is a phenomenon where loose, relatively clean, near-surface sandy soil located above the water table is densified from vibratory loading, typically from strong seismic shaking or vibratory equipment. The site soils above the water table generally consist of layers of very stiff to hard sandy clay. Therefore, in our opinion, dynamic settlement and/or any potential effect of dynamic settlement on the proposed construction is not expected to be significant.

5.1.4 Fault Ground Rupture and Fault Creep

The State of California adopted the Alquist-Priolo Earthquake Fault Zone Act of 1972 (Chapter 7.5, Division 2, Sections 2621 – 2630, California Public Resources Code), which regulates development near active faults for the purpose of preventing surface fault rupture hazards to structures for human occupancy. In accordance with the

Alquist-Priolo (A-P) Act, the California Geological Survey established boundary zones or Earthquake Fault Zones surrounding faults or fault segments judged to be sufficiently active, well-defined and mapped for some distance.

Structures for human occupancy within designated Earthquake Fault Zone boundaries are not permitted unless surface fault rupture and fault creep hazards are adequately addressed in a site-specific evaluation of the development site.

The site is not currently within a designated Earthquake Fault Zone as defined by the State (Hart and Bryant, 1997) or any local zone. Based on our evaluation, the potential for fault ground rupture or creep at the site is very low to nil.

5.2 Expansive Soils

The near surface soils observed and/or sampled during the exploration program generally consisted of a thick layer of moderate to high plastic and moderate to high expansive fine-grained sandy clay. We did not encounter any potentially highly expansive soil. However, we are still including recommendations to mitigate expansive soil conditions, consisting of combinations of moisture conditioning of the subgrade for this site. Specific measures to mitigate the potential effects of moderate expansive soils on foundations and concrete are presented herein.

5.2 Consolidation Settlement

Consolidation is the densification of soil into a denser arrangement from additional loading, such as from new fills or foundation loads. Consolidation of clayey soils is usually a long-term process, whereby the water is squeezed out of the soil matrix with time. Sandy soils consolidate relatively rapidly with an introduction of a load.

Consolidation of soft and loose soil layers and lenses can cause settlement of the ground surface or buildings.

Based on dense subsurface site soils, the near-surface soils are considered to have a minimal potential for consolidation settlement.

6.0 GEOTECHNICAL ENGINEERING CONCLUSIONS AND RECOMMENDATIONS

The following Geotechnical engineering conclusions and recommendations are based upon the analysis of the information gathered during the course of this study and our understanding of the proposed improvements.

6.1 Conclusions

The site is considered suitable from a geotechnical and geologic perspective for the proposed development provided the recommendations of this report are incorporated into the design and implemented during construction. The predominant geotechnical and geological issues that will need to be addressed at this site are summarized below.

Seismic Considerations – The site is located within a seismically active region and expected to be subjected to moderately strong shaking during the life of the new structures. As a minimum, the solar panel structure designs should consider the effects of seismic activity in accordance with the latest edition of the California Building Code

(CBC).

Corrosivity – The site soil is classified as corrosive to cast and ductile iron pipe and use of cathodic corrosion protection is often recommended. For specific long-term corrosion control design recommendations, we recommend that a California-registered professional corrosion engineer evaluate the corrosion potential of the soil environment on buried concrete structures, steel pipe coated with cement-mortar, and ferrous metals.

6.2 Seismic Parameters

The subject site is located within a seismically active region and should be designed to account for earthquake ground motions as described in this report. Based on the subsurface conditions encountered and our evaluation of the geology of the site, Site Class “D”, representative of stiff and dense soils averaged over the uppermost 100 feet of the subsurface profile would be appropriate for this site.

For seismic analysis of the proposed site in accordance with the seismic provisions of the 2019 California Building

Code (CBC), we recommend the following seismic ground motion values be used for design shown in Table 4, which are based on procedures outlined in ASCE 7-16 Section 11.4 and Table 11.4-2 of Supplement 1. ASCE 7-16

Section 11.4.8 states that a site-specific ground motion hazard analysis should be performed for all structures on

Site Class D soils with S1 greater than or equal to 0.2, unless the exceptions outlined in Section 11.4.8 are followed and the seismic response coefficient is properly modified during design. A site-specific ground motion hazard analysis was not performed for this site and is outside the scope of this report. If a site-specific ground motion hazard analysis is required for this project or if the project is designed under a different building code than CBC

2019, we should be notified so that we may properly update the seismic design parameters.

Table 4: Seismic Design Parameters Based on 2019 CBC (per ASCE 7-16)

Item Value 2016 CBC SourceR1 ASCE 7-10 Table/FigureR2

Site Class D Table 1613A.3.2 Table 20.3-1 Mapped Spectral Response Accelerations Short Period, SS 1-second Period, S1

1.522 g

0.555 g

Figure 22-1 Figure 22-2

Site Coefficient, Fa 1.2 Table 1613A.3.3(1) Table 11.4-1 Site Coefficient, Fv * 1.8 Table 1613A.3.3(2) Table 11.4-2 MCE (SMS) 1.827 g Equation 16A-37 Equation 11.4-1 MCE (SM1) 0.999 g Equation 16A-38 Equation 11.4-2 Design Spectral Response Acceleration Short Period, SDS 1-second Period, SD1**

1.218 g

0.666 g

Equation 16A-39 Equation 16A-40

Equation 11.4-3 Equation 11.4-4

Peak Ground Acceleration (PGAM) 0.649 g - Equation 11.8-1

R1: California Building Standards Commission (CBSC), “California Building Code,” 2019 Edition.

R2: U.S. Seismic “Design Maps” Web Application, https://seismicmaps.org/ *Fv are based off Table 11.4-2 from the ASCE 7-16 Supplement 1 **The above design spectral response acceleration parameters may only be used provided that the exception outlined in section 11.4.8 of ASCE 7-16 is met.

6.3 Site Grading

6.3.1 General Grading and Material Requirements

Site grading is generally anticipated to consist of finish grading to establish site grades, or additional mass grading for improved foundation bearing capacities if desired; utility trench excavation and backfills, preparation of supporting subgrades for site pavements and hardscape; and placement of aggregate base (baserock) sections for hardscape and pavements.

On-site soils having an organic content of less than three percent by weight and Plasticity Index of less than 15 can be reused as fill as approved by the Geotechnical Engineer. Imported soil should be non-expansive, having a

Plasticity Index of 15 or less, an R-Value greater than 40, and contain sufficient fines so the soil can bind together.

Imported materials should be free of environmental contaminants, organic materials and debris, and should not contain rocks or lumps greater than three inches in maximum size. Import fill materials should be approved by the

Geotechnical Engineer prior to use on site.

https://seismicmaps.org/

6.3.2 Project Compaction Recommendations

The following table summarizes the recommended minimum compaction requirements for this project. Not all soils, aggregates, and scenarios listed below may be applicable for this project. Specific grading recommendations will be discussed individually within applicable sections of this report.

Table 5: Project Compaction Recommendations

Description Percent Relative

Compaction Minimum Percent Above Optimum

Moisture Content AC or Concrete Pavement, Subgrade, Upper 6” 95 3 to 5 AC or Concrete Pavement, Onsite Soil or Fill 90 2 AC or Concrete Pavement, Class 2 Baserock 95 2 AC or Concrete Pavement, Treated Soil, Subgrade 93 2 Concrete Flatwork, Class 2 Baserock 90 2 Concrete Flatwork, Subgrade Soil 90 3 to 5 Underground Utility Trench Backfill 90 2 Underground Utility Trench Backfill - Landscape Areas (not including areas below flatwork) 85 2

Underground Utility Trench Backfill, Clean Sand 95 4 Underground Utility Trench Backfill, Upper 3’ Feet below Existing Pavement Sections or 6” below New Pavement Sections 95 2

Engineered fill materials should be properly moisture conditioned in accordance with Table 5 as determined using

ASTM D-1557 and placed in uniform loose lifts not to exceed eight inches. Smaller lifts may be necessary to achieve the minimum required compaction using lighter weight compaction equipment. It should be noted that the use of on-site soils for fill will require moisture conditioning (drying or wetting). Moisture conditioning may be difficult to achieve during cold, wet periods of the year, or during extreme temperatures and after precipitation events.

6.4 Foundations Recommendations

6.4.1 Drilled Pier Foundations

The foundation for the proposed solar panel structures may consist of drilled pier foundations, deriving their vertical supporting capacity through skin friction between the side surfaces of the foundations and the adjacent soil. For design purposes, soil Class Z (precheck design by 4Steel structural engineering) could be used and the allowable skin friction for gravity loads may be assumed to be 425 psf for the portion of pier embedded in native soils, with the upper two foot of the pier to be neglected. If the drilled piers are within a paved area, this reduction can be reduced to 1-foot. This value may be increased by one-third for seismic or transient loads. Uplift loads should be limited to 0.8 times these values.

Lateral resistance for drilled pier foundations may be determined for onsite soils using an allowable passive resistance equal to an equivalent fluid weighing 400 pounds per cubic foot (pcf) acting against the foundation for lateral load resistance against the sides of foundations perpendicular to the direction of loading where the foundation is poured neat against undisturbed material (i.e., native soils, engineered fills or existing fills). For pier foundations, passive pressure can be assumed to act across two times the pier diameter. Geo-Eng personnel should be retained to observe and confirm that soil or bedrock encountered during footing excavations, prior to formwork and reinforcing steel placement, is consistent with the assumptions of this report. If unsuitable soil or bedrock is present, the excavation should be deepened until suitable supporting material is encountered.

Although the near surface soils were generally cohesive, isolated sand layers can be encountered requiring casing or use of drilling mud if encountered. Any pier constructed below groundwater should either be pumped dry or use the tremie method of concrete placement as part of the pier construction. All piers should be poured the same day as drilling if groundwater is encountered.

6.4.2 Spread Footing Foundations

We anticipate that the carport solar panel structures can also be supported on continuous and/or isolated spread footings bearing on undisturbed very stiff to hard native soil or engineered fill. Where over excavations below design footing depth is required, the over excavated portion of footing excavation should be backfilled with structural or lean concrete or a Controlled Low Strength Material (CLSM). Footings should be founded a minimum of 24 inches below lowest adjacent finished grade. Continuous footings should have a minimum width of at least

18 inches, and isolated column footings should have a minimum width of at least 24 inches. In addition, footings located adjacent to other footings or utility trenches should bear below an imaginary 1.5:1 (horizontal to vertical) plane projected upward from the bottom edge of the adjacent footings or utility trenches. Footing reinforcement should be determined by the project Structural Engineer.

Footings should be designed for the following allowable bearing pressures, assuming design Factors-of-Safety of

3.0, 2.0 and 1.5 for dead loads, dead plus live loads, and total loads, respectively, from the calculated ultimate bearing pressure.

Table 6: Allowable Bearing Pressures for Spread Footings

Load Condition Allowable Bearing Pressure (psf)

Dead Load 3,000

Dead plus Live Loads 4,000

Total Loads (including wind or seismic) 5,000

These allowable bearing pressures are net values; therefore, the weight of the footing can be neglected for design purposes. Footings should be designed with sufficient reinforcing to provide structural continuity and permit spanning of local irregularities.

If site preparation and foundation observation services are conducted as outlined in the Geotechnical Study report, vertical static settlement is expected to be less than one inch for footings bearing within the materials described in the report and designed to the allowable bearing pressures. Differential settlement across the structure is not expected to exceed about ½ this value within a 30-foot span.

6.4.3 Lateral Resistance

Shallow foundations can resist lateral loads with a combination of bottom friction and passive resistance. An allowable coefficient of friction of 0.35 between the base of the foundation elements and underlying material is recommended. In addition, an ultimate passive resistance equal to an equivalent fluid weighing 350 pounds per cubic foot (pcf) acting against the foundation may be used for lateral load resistance against the sides of footings perpendicular to the direction of loading where the footing is poured neat against undisturbed material. The top foot of passive resistance at foundations not adjacent to pavement or hardscape should be neglected. To fully mobilize this passive resistance, a lateral footing deflection on the order of one to two percent of the embedment of the footing is required. If it is desired to limit the amount of lateral deflection to mobilize the passive resistance, a proportional safety factor should be applied. The friction between the bottom of a slab-on-grade floor and the underlying soil should not be utilized to resist lateral forces.

6.4.4 Construction Considerations

Geo-Eng personnel should be retained to observe and confirm that footing excavations prior to formwork and reinforcing steel placement bear in soils suitable for the recommended maximum design bearing pressure. If unsuitable soil is encountered, the excavation should be deepened until suitable supporting material is encountered. The over excavation should be backfilled using engineered soil or lean concrete (or a sand-cement slurry mix acceptable to the Geotechnical Engineer) up to the bottom of the footing concrete.

Footing excavations should have firm bottoms and be free from excessive slough prior to concrete or reinforcing steel placement. Care should also be taken to prevent excessive wetting or drying of the bearing materials during construction. Extremely wet or dry or any loose or disturbed material in the bottom of the footing excavations should be removed prior to placing concrete. If construction occurs during the winter months, a thin layer of concrete (sometimes referred to as a rat slab) could be placed at the bottom of the footing excavations. This will protect the bearing material and facilitate removal of water and slough if rainwater fills the excavations.

6.5 Temporary Excavation Slopes

The Contractor should incorporate all appropriate requirements of OSHA and Cal OSHA into the design of any temporary construction slopes used during construction. Excavation safety regulations are provided in the OSHA

Health and Safety Standards for Excavations, 29 CFR Part 1926, Subpart P, and apply to excavations greater than five feet in depth.

The Contractor, or his specialty subcontractor, should design temporary construction slopes to conform to the

OSHA regulations and should determine actual temporary slope inclinations based on the subsurface conditions exposed at the time of construction. For pre-construction planning purposes, the subsurface materials in the areas of the site where excavation may take place may be assumed to consist of granular soils categorized as OSHA Type

B with temporary slope inclination of no steeper than 1:1 (horizontal to vertical). This maximum slope ratio is assumed to be uniform from top to toe of the slope. The type of slope material and actual temporary construction slopes should be confirmed during construction by a competent engineering geologist responsible to the grading contractor.

If temporary slopes are left open for extended periods of time, exposure to weather and rain could have detrimental effects such as sloughing and erosion on surficial soils exposed in the excavations. We recommend that all vehicles and other surcharge loads be kept at least 10 feet away from the top of temporary slopes, and that such temporary slopes are protected from excessive drying or saturation during construction. In addition, adequate provisions should be made to prevent water from ponding on top of the slope and from flowing over the slope face. Desiccation or excessive moisture in the excavation could reduce stability and require shoring or laying back side slopes.

6.6 Utility Trench Construction

Utility trenches may be backfilled with approved native soil above the utility bedding and shading materials compacted to the recommended compaction presented in Table 5. If rocks larger than four inches in maximum size are encountered, these should be removed from the fill prior to placement in the utility trenches. Utility bedding and shading compaction requirements should be in conformance with the requirements of the local agencies having jurisdiction and as recommended by the pipe manufacturers. Jetting of trench backfill is not recommended.

Pea gravel, rod mill (pea gravel with sand), or other similar self-compacting material should NOT be utilized as trench backfill at the site. This material may act as a conduit for subsurface moisture migration. Utility trenches ideally should be completely sealed/cut-off with concrete, clayey soil, sand-cement slurry, or controlled density fill (CDF) where the utility enters the building under the perimeter foundation. This would reduce the potential for migration of water beneath the building through the shading material in the utility trench.

If rain is expected and the trench will remain open, the bottom of the trench may be lined with one to two inches of gravel. This would provide a working surface in the trench bottom. The trench bottom may have to be sloped to a low point to pump the water out of the trench.

6.7 Validity of Report

This report is valid for three years after publication. If construction begins after this time period, Geo-Eng should be contacted to confirm that the site conditions have not changed significantly. If the proposed development differs considerably from that described above, Geo-Eng should be notified to determine if additional recommendations are required. Additionally, if Geo-Eng is not involved during the geotechnical aspects of construction, this report may become wholly or in part invalid since Geo-Eng’s geotechnical personnel need to verify that the subsurface conditions anticipated preparing this report are similar to the subsurface conditions revealed during construction. Geo-Eng’s involvement should include foundation and grading plan review;

observation of foundation excavations; grading observation and testing; testing of utility trench backfills and retaining wall backfill as applicable to the project; and subgrade preparation in flatwork areas.

7.0 LIMITATIONS AND UNIFORMITY OF CONDITIONS

The recommendations of this report are based upon the soil and conditions encountered in the field explorations

(i.e., borings). If variations or undesirable conditions are encountered during construction, Geo-Eng should be contacted so that supplemental recommendations may be provided.

This report is issued with the understanding that it is the responsibility of the owner or his representatives to see that the information and recommendations contained herein are called to the attention of the other members of the design team and incorporated into the plans and specifications, and that the necessary steps are taken to see that the recommendations are implemented during construction.

The findings and recommendations presented in this report are valid as of the present time for the development as currently proposed. However, changes in the conditions of the property or adjacent properties may occur with the passage of time, whether by natural processes or the acts of other persons. In addition, changes in applicable or appropriate standards may occur through legislation or the broadening of knowledge. Accordingly, the findings and recommendations presented in this report may be invalidated, wholly or in part, by changes outside our control. Therefore, this report is subject to review by Geo-Eng after a period of three (3) years has elapsed from the date of issuance of this report. In addition, if the currently proposed design scheme as noted in this report is altered, Geo-Eng should be provided the opportunity to review the changed design and provide supplemental recommendations as needed.

Recommendations are presented in this report which specifically request that Geo-Eng be provided the opportunity to review the project plans prior to construction and that we be retained to provide observation and testing services during construction. The validity of the recommendations of this report assumes that Geo-Eng will be retained to provide these services.

This report was prepared upon your request for our services, and in accordance with currently accepted geotechnical engineering practice. No warranty based on the contents of this report is intended, and none shall be inferred from the statements or opinions expressed herein. The scope of our services for this report did not include an environmental assessment or investigation for the presence or absence of wetlands or hazardous or toxic materials in the soil, surface water, groundwater or air, on, below or around this site. Any statements within this report or on the attached figures, logs or records regarding odors noted or other items or conditions observed are for the information of our client only.

8.0 REFERENCES

United Soil Engineering, Inc., Geotechnical Investigation & Pavement Design, March 2011, Proposed R&D Building, Southwestern Corner of Cushing Parkway and Fremont Boulevard, Fremont California.

American Concrete Institute, 2008, Guide for Design and Construction of Concrete Parking Lots: ACI Publication 330R-08.

American Society of Civil Engineers, 2010, Minimum Design Loads for Buildings and Other Structures; ASCE/SEI Standard 7-10.

Association of Bay Area Governments (ABAG), September 2003, Liquefaction Susceptibility maps, based on William Lettis and Associates and USGS mapping, website: http://www.abag.ca.gov

Blake, Thomas F., EQSearch version 3.00, EQFault1 version 3.00, FriskSP version 4.00, software and manuals with 2004 CGS fault model updates.

California Department of Transportation (Caltrans), Memorandum: Foundation Report for Laurel Curve Soil Nail Wall

California Department of Transportation (Caltrans), ARS Online Website: http://dap3.dot.ca.gov/ARS_Online/ (Accessed May 2018)

California Division of Mines and Geology (CDMG), Digital Images of Official Maps of Alquist-Priolo Earthquake Fault Zones of California, Central Coast Region, DMG CD 2000-004, 2000.

California Division of Mines and Geology (CDMG), 1996, Probabilistic Seismic Hazard Assessment for the State of California: CDMG Open-File Report 96-08.

California Geological Survey, 2008, Guidelines for evaluating and mitigating seismic hazards in California: California Geological Survey Special Publication 117A, 98 p.

California Geological Survey, 1996, Probabilistic seismic hazard assessment for the state of California, DMG Open- File report 96-08 (USGS Open-File Report 96-706), and updated Appendix A, Appendix A – 2002 California Fault Parameters.

Cao, T., Bryant, W.A., Rowshandel, B., Branum, D., and Wills, C.J., The Revised 2002 California Probabilities Seismic Hazard Maps, June 2003.

Wagner, D.L., Bortugno, E.J., and McJunkin, R.D., 1991, Geologic map of the San Francisco-San Jose quadrangle, California, 1:250,000: California Division of Mines and Geology, Regional Geologic Map 5A, scale 1:250,000.

Hart, E. W., 1983, Summary Report: Fault Evaluation Program, 1981 – 1982, Area-Northern Coast Ranges region, California, California Department of Conservation, Division of Mines and Geology, Open-File Report 83-10.

Hart, E.W., and Bryant, W.A., 1997, Fault-rupture hazard zones in California: California Geological Survey Special Publication 42, revised 1997 with Supplements 1 and 2 added 1999, 38 p.

http://www.abag.ca.gov/ http://dap3.dot.ca.gov/ARS_Online/

Jennings, C.W., and Bryant, W.A., compilers, 2010: 2010 Fault activity map of California: California Geological Survey, Geologic Data Map No. 6, scale 1:750,000, with 94-page Explanatory Text booklet.

Page, B.M., 1966, Geology of the Coast Ranges of California: in Bailey, E.H., Jr., editor, Geology of Northern California: California Geological Survey Bulletin 190, p. 255-276.

Thrust Fault Subgroup 1999, Report to the Working Group on Northern California Earthquake Probabilities, 15 p.

plus tables.

Tokimatsu, K. and Seed, H.B., 1987, Evaluation of Settlements in Sands due to Earthquake Shaking: ASCE Journal of Geotechnical Engineering, Vol. 113, No. 8, pp. 861-878.

University of California, Berkeley, Bancroft Library: Historic Maps of California – San Francisco Bay Area:

http://sunsite.berkeley.edu/histopo/

U.S. Department of Agriculture, Natural Resources Conservation Service, Web Soil Survey;

http://websoilsurvey.nrcs.usda.gov/app/WebSoilSurvey.aspx

U.S. Geological Survey, 1999, Earthquake probabilities in the San Francisco Bay region: 2000 to 2030 – A summary of findings, by Working Group on California Earthquake Probabilities, Open File Report 99-517, Online Version 1.0.

U. S. Geological Survey Earthquake Information Center, 2003, website earthquake.usgs.gov.

U. S. Geological Survey, Earthquake Hazards Program website eqhazmaps.usgs.gov.

2007 Working Group on California Earthquake Probabilities (WGCEP), 2008, The Uniform California Earthquake Rupture Forecast, Version 2 (UCERF 2): U.S. Geological Survey Open-File Report 2007-1437.

Wagner, D. L., and others, compilers, 1991, Geologic map of the San Francisco – San Jose quadrangle: California Geological Survey, Regional Geologic Map 5A; scale 1:250,000.

Youd, T.L., and Hoose, S.N., 1978, Historic ground failures in northern California triggered by earthquakes: U.S.

Geological Survey Professional Paper 993, 177 p., 5 pls. in pocket.

Youd, T.L., Idriss, I.M., Andrus, R.D., Arango, I., Castro, G., Christian, J.T., Dobry, R., Finn, W.D.L., Harder, L.F. Jr., Hynes, M.E., Ishihara, K., Koester, J.P., Liao, S.S.C., Marcuson, W.F. III, Martin, G.R., Mitchell, J.K., Moriwaki, Y., Power, M.S., Robertson, P.K., Seed, R.B., and Stokoe, K.H. II, 2001, Liquefaction Resistance of Soils: Summary Report from the 1996 NCEER and 1998 NCEER/NSF Workshops on Evaluation of Liquefaction Resistance of Soils:

ASCE Journal of Geotechnical and Environmental Engineering, Vol. 127, No. 10, October 2001, p. 817-833.

Publications may have been used as general reference and not specifically cited in the report text.

http://sunsite.berkeley.edu/histopo/ http://websoilsurvey.nrcs.usda.gov/app/WebSoilSurvey.aspx

FIGURES

Figure 1 – Site Vicinity Map Figure 2 – Site Development Plan Figure 3 – Site Map and Boring Locations Figure 4 – Site Vicinity Geologic Map Figure 5 – Regional Fault Map

SiteSiteSite

N

Map Scale

Figure 1Site Vicinity Map

February 2021

72-1304Municipal Service Center 1993 Rancho Conejo Blvd, Thousand Oaks, California

Source: USGS, Newbury Park Quadrangle, California-Ventura County, TNM Geospatial, 2018

D

P.L. 104.54' P.L. 25.44'

P .L

.7

P .L

.7

90.41'51.50'

P.L. 109.96'

(E

R E

S

ID

E N

C E

P.L. 90.00'

P.L. 78.50'

P .L

.7

.0

North

R

0.

(P

R E

S

ID

E N

C E

A

(P

R E

S

ID

E N

C E

B

P .L

.0

.9

1'

.5

28.00'

PONY LANE

P A

L M

S D

R

IV

E

P.L. 110.00'

FRONT

S.B.

20' - 0"

SI

D

E S.

B.

2ND

15' - 0"

SI

D

E S.

B.

5'

0"

S

5' - 0"

2N D

F R

O N

T S.

B.

FR

O

N T

S.

B.

R

0"

R

0"

2N D

F R

O N

T S.

B.

2N D

F R

O N

T S.

B.

ONT S.B.

S

5' - 0"

P.L. 84.57'

STREETDEDICATION

25' - 5"

P .L

.0

- Proposed Parking Lot Footprint

E lliot R oad

A

A'

- Geologic Cross-Section

- Proposed Building Footprint

- Proposed Solar Arrays

A

A’

- Approximate Fence Location Areas

- Approximate Fault Trench Location

B-1

- Approximate Soil Boring Locations, Fugro 2005 and 2007 - Approximate Soil Boring Locations, MWH 2001

- Approximate Soil Boring Locations, Geosphere 2009 - Approximate Soil Boring Locations, Fugro 2005

B-2 B-3

B-4

Figure 2Site Development Plan

B-6

B-5

B-8B-7 A

B-2

B-4

Approximate boring location

Geologic contact

B-1 B-3

A’

Cross section path

A A’ n

A

A’

B-1

B-5

A

B’

0' 10' 20' 40' 80'

1" = 20'-0"

Site Plan, Proposed

B-2

B-3

A’

B-2

B-3

B-4

CPT-1

B-2

CPT-4

CPT-3

CPT-2

B-1

B-3

B-5

B-6

B-4 B-8

B-9

CPT-1CPT-2

CPT-4

CPT-3

B-2

B-6

B-4

B-3B-8

B-9

HA-1

KB-1 KB-2

Approximate CPT location

Approximate hand auger location

Approximate previous boring location (Krazan 2009)

HA-2

B-2

B-1

CPT-1

N

B-1

B-2

B-3

CPT-2 CPT-3

CPT-1

Approximate boring location

Approximate CPT location

B-4

B-5 B-6

February 2021 72-1304

B-4

B-5B-6

Municipal Service Center 1993 Rancho Conejo Blvd, Figure 3Site and Boring Location Plan

Qha

Base Map Reference: Google Earth

Qha

B-1

B-2

B-3

N

Approximate boring location

Kp: Panoche Formation, Clay shale or Claystone, Cretaceous

Qha

Qha

B-2

B-1

Qha

Geologic Cross Section

B-2

B-3

B-1

Kp

Qha

A

A’

Kp

Kp

CPT-1

B-1

CPT-4

CPT-3

B-2

B-1

B-4

B-3

B-8

B-9

Approximate CPT location

Approximate hand auger location

Approximate previous boring location (Krazan 2009)

HA-1

KB-1 KB-2

HA-2

A

A’

Approximate property line

B-4

B-5 B-6

B-2

B-3

B-4

CPT-3

CPT-2

CPT-1

February 202172-1304

B-1

B-4

B-5

B-2

B-3

B-6

Municipal Service Center

Qt fsr - Franciscan Complex Melange, Eocene, Paleocene &/or Late Cretaceous Kfs - Franciscan Sedimentary Rock, Cretaceous

Figure 4Site Vicinity…