Att_5_TLHQ_Geotech__FINAL.pdf

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SUBMITTED TO:

DOWL

4041 B Street Anchorage, AK 99503

BY:

Shannon & Wilson, Inc.

1722 3rd Street, Ste 100 Sacramento, CA 95811

916-438-2300 www.shannonwilson.com

GEOTECHNICAL REPORT

Tulelake NWR Headquarters

TULELAKE, CA

October 20, 2020

Shannon & Wilson No: 104644-001

Final Geotechnical Report

104644-001 October 20, 2020

PAGE INTENTIONALLY LEFT BLANK FOR DOUBLE-SIDED PRINTING

10/20/2020-104644-001_R01 FINAL.docx i

Submitted To: DOWL

4041 B Street

Anchorage, AK 99503

Attn: Bradley Doggett, PE

Subject: FINAL GEOTECHNICAL REPORT, TULELAKE NWR HEADQUARTERS, TULELAKE, CA

Shannon & Wilson prepared this report and participated in this project as a subconsultant to

DOWL. Our scope of services was specified in Agreement Number ANC63163‐03 with

DOWL, dated June 25, 2020. We previously submitted a draft report on August 12, 2020.

This final report supersedes the draft report.

We appreciate the opportunity to be of service to you on this project. If you have questions concerning this report, or we may be of further service, please contact us.

Sincerely, SHANNON & WILSON, INC.

Debanik Chaudhuri, Ph.D., G.E.

Senior Associate

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CONTENTS

1 Introduction

1.1 General

1.2 Scope of Services

2 Site and Project Description

3 Subsurface Explorations

4 Laboratory Testing

5 Site Geology and Subsurface Conditions

5.1 Site Geology

5.2 Subsurface Conditions

5.3 Groundwater

6 Conclusions and Recommendations

6.1 General

6.2 Seismic Design

6.3 Liquefaction, Seismic Settlement, and Cyclic Softening

6.4 Expansive Soil Conditions

6.5 Soil Corrosion Potential

6.6 Foundation Design

6.6.1 Mitigation Measure

6.6.2 Allowable Bearing Pressure

6.6.3 Settlement

6.6.4 Lateral Resistance

6.7 Slab-on-Grade Floors

6.8 Pavement Design

7 Construction Considerations

7.1 General

7.2 Site Preparation

7.3 Subgrade Preparation

7.3.1 Building Subgrade

7.3.2 Subgrade for Pavement and Driveway

7.4 Materials for Fill

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7.5 Fill Placement

7.6 Pavement

7.6.1 Aggregate Base

7.6.2 Asphalt Concrete

7.7 Dewatering

7.8 Wet-Weather Considerations

8 Limitations

9 References

Exhibits Exhibit 6-1: 2019 CBC Seismic Parameters (Site Class E) Exhibit 6-2:: Corrosion Testing Results

Figures Figure 1: Vicinity Map Figure 2: Site Plan

Appendices Appendix A: Subsurface Explorations Appendix B: Geotechnical Laboratory Testing Important Information iv

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ACRONYMS

AB Aggregate Base ASTM American Society for Testing and Materials bgs below ground surface Caltrans California Department of Transportation CBC California Building Code psf pounds per square foot ks Modulus of subgrade reaction NWR National Wildlife Refuge pci pounds per cubic inch SPT Standard Penetration Test

104644-001 October 20, 2020

1 INTRODUCTION

1.1 General

Shannon & Wilson prepared this Final Geotechnical Report in support of the design and construction of proposed Tulelake National Wildlife Refuge (NWR) headquarters building located near Tulelake, California. The report presents our geotechnical recommendations in support of design of various project elements, including foundations, floor slab, and site grading. Our understanding of the project is based on information provided by DOWL, which includes a US Fish & Wildlife Services Statement of Work, dated November 15, 2019, ;

a schematic plan showing site layout; and a structural memorandum, dated July 23, 2020.

We understand that DOWL will prepare 35 percent design for the project. The final design will be prepared by a design-build contractor.

Our conclusions and recommendations are based on subsurface information collected from three exploratory borings drilled for the project, laboratory testing on selected soil samples from the borings, and our characterization of subsurface conditions at the site.

1.2 Scope of Services

The purpose of our study is to evaluate subsurface conditions and provide geotechnical conclusions and recommendations regarding design and construction of the project. Our scope of services is described in detail in our proposal dated January 6, 2020 and includes the following tasks:

Perform data review, perform subsurface explorations, perform geotechnical laboratory testing, perform engineering analyses, and prepare this report summarizing our findings and recommendations.

The limitations of our report are discussed in Section 8, Limitations.

2 SITE AND PROJECT DESCRIPTION

The proposed new Tulelake NWR Headquarters building will replace the existing headquarters facility located at 4009 Hill Road in Tulelake, California. The existing headquarters building was constructed in 1981. Although the building was upgraded over

104644-001 October 20, 2020 the years, it is currently considered seismically deficient and deemed beyond repair. The existing building will remain functional until the replacement building is constructed and occupied. The existing parking area will be used for visitor overflow.

The proposed building will be on the east side of Hill Road, across from the existing facility and will be a single-story structure with a footprint area of approximately 5,000 square feet.

The building will likely have a wood-truss framed roof supported on perimeter stud-bearing walls. The structural loads (dead + live) on the perimeter foundation are expected to be about 1,500 pounds per lineal foot. Additional at-grade parking area is proposed.

The site of the proposed building currently serves as a parking lot for the Discovery Marsh Trail and is relatively flat. As part of construction, the parking lot will be expanded to the west and north of the proposed building. An existing education center building is on the northeast portion of the site which, will likely be removed as part of the project scope. A drainage channel runs in an east-west direction approximately 40 feet south of the proposed building.

3 SUBSURFACE EXPLORATIONS

We completed three exploratory borings at the site. Borings designated B-1 and B-2 were drilled at the proposed location for the new headquarters building and boring B-3 at the proposed parking area expansion. The approximate locations of the borings are presented in Figure 2, Site and Exploration Plan.

Under a subcontract with Shannon & Wilson, Taber Drilling of West Sacramento, California, advanced the borings using solid-stem auger and mud rotary drilling methods. The borings B-1 through B-3 were drilled on July 1, 2020 to depths of 51.5 feet, 21.5 feet, and 11.5 feet, respectively below ground surface (bgs).

We performed Standard Penetration Tests (SPTs) at regular intervals and collected soil samples. We collected a single, larger diameter, relatively undisturbed sample using a Modified California sampler. A Shannon & Wilson field representative observed the drilling, penetration tests and soil sampling, and prepared field logs of the borings.

Appendix A, Subsurface Explorations, presents the boring logs and the drilling and sampling methods in greater detail.

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4 LABORATORY TESTING

Geotechnical laboratory tests were performed on selected soil samples collected from the borings. The laboratory tests included visual classification, natural moisture content determination, grain-size analysis, Atterberg limits, one-dimensional consolidation, R-value, expansion index, and soil corrosivity. Descriptions of laboratory test procedures and test results are presented in Appendix, Geotechnical Laboratory Testing. The moisture content, percent fines (particles finer than 0.075 mm), and Atterberg limit test results are incorporated into the boring logs presented in Appendix A, Subsurface Explorations.

5 SITE GEOLOGY AND SUBSURFACE CONDITIONS

5.1 Site Geology

The project site is located at the former edge of Tule Lake, near the base of a north-south trending ridge that lies to the west of the site. Our understanding of the geology of the area is based on our review of Gay and Aune (1958), and Donnelly-Nolan and Champion (1987).

Tule Lake is in a basin formed by volcanism and down-dropped blocks resulting from extensional tectonics. Portions of the lake were converted to agriculture fields before the US Fish and Wildlife Service converted the area to a wildlife refuge. The north-south ridge west of the site is underlain by Tertiary volcanic pyroclastic rock. Pleistocene to recent lacustrine (lake) deposits are mapped across the flat ground east of the ridge, which comprise silt and clay with some organic muck and diatom-rich deposits.

5.2 Subsurface Conditions

All three borings encountered near-surface sandy soil consisting primarily of loose to medium dense silty sand. This surficial layer extends 5 to 11 feet or more below ground surface. Boring B-1, which was drilled to a depth of about 51 feet bgs, encountered very soft to soft elastic silt underlying the surficial sandy soil between depths of 5 to 51 feet. Elastic silt was encountered in B-2 below 7 feet. Boring B-3 did not encounter the elastic silt layer to the depth explored, which was about 11 feet.

The elastic silt is highly plastic with natural water contents up to 172 percent. In some cases, the natural water content is greater than the Liquid Limit of the soil. The soil exhibits high compressibility. Some of these characteristics can be attributed to diatomaceous contents of the soil. For specific soil information, refer to the boring logs provided in Appendix A and laboratory results presented in Appendix B.

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5.3 Groundwater

The subsurface exploration encountered groundwater at a depth of 6 feet bgs in boring B-1 and 5 feet bgs in boring B-2. Due to the presence of fine-grained soils, the recorded groundwater depths may not represent the actual groundwater level. The groundwater depth is expected to vary depending on the season, rainfall, irrigation, and other factors.

6 CONCLUSIONS AND RECOMMENDATIONS

6.1 General

The presence of loose sandy soils and compressible cohesive soils beneath the site, present some geologic and geotechnical constraints to design and construction of the proposed building. Primary design issues include liquefaction of the loose sandy soils, liquefaction-induced ground settlement and loss of strength of the silt layer during a design seismic event, and consolidation settlement of the soft elastic silt layer.

These problems likely could be avoided by relocating the proposed building to west side of Hill Road near or at the location of the existing building. The available geologic and soils maps, and geomorphology indicate the subsurface condition are more favorable west of Hill Road. However, that would alter project planning and schedule.

In this section, we provide our conclusions and recommendations for designing and constructing the proposed building at the currently proposed location. Our conclusions and recommendations include engineering mitigation measures for the design issues outlined above. Construction considerations for successful implementation of our design recommendations are provided in Section 7.

6.2 Seismic Design

We assume the 2019 California Building Code (CBC) will be used as the basis of design on the project. The 2019 CBC seismic design parameters are based on a maximum considered earthquake that corresponds to ground motions with a 2% probability of exceedance in 50 years, or about a 2,500-year return period.

Based on the SPT blow counts obtained during our subsurface exploration and assumed soil properties below depths of explorations, we recommended the project site be classified as Site Class E, corresponding to a "Soft clay soil" profile. We used the SEAOC/OSHPD online tool to calculate seismic design parameters corresponding to Site Class E, which are presented in Exhibit 6-2 below.

Exhibit 6-1: 2019 CBC Seismic Parameters (Site Class E)

Seismic Parameter Peak Ground Acceleration

(g) Short Period

(g) Long Period

(g)

Mapped SRA PGA = 0.394 SS = 0.876 S1 = 0.332

Site Coefficients FPGA = 1.412 Fa = 1.3 Fv = 2.67

MCE SRA PGAM = 0.556 SMS = 1.139 SM1 = 0.886

Design SRA SDS = 0.759 SD1 = 0.585

NOTES:

SRA = site response acceleration; MCE = maximum considered earthquake; PGA = peak ground acceleration; FPGA = PGA site factor;

PGAM = maximum risk-adjusted PGA; SS = mapped short-period spectral acceleration; S1 = mapped long-period spectral acceleration;

Fa = short-period site coefficient; Fv = long-period site coefficient; SMS = adjusted short-period maximum spectral acceleration; SM1 = adjusted long-period maximum spectral acceleration; SDS = short-period design spectral acceleration; SD1 = long-period design spectral acceleration

We note that ASCE 7-16 requires site-specific ground motion analysis for Site Class E with certain exceptions, depending on the natural period of the structure. Based on the information provided by the structural engineer from DOWL, site-specific ground motion analysis in not needed for the proposed structure. We also note that the SEAOC/OSHPD online tool does not provide values of Fv and SM1. The values presented in Exhibit above are based on the information provided by the structural engineer.

6.3 Liquefaction, Seismic Settlement, and Cyclic Softening

Liquefaction is a phenomenon in which pore pressure in loose, saturated, granular soil increases during ground shaking to a level near the initial vertical effective stress, resulting in a reduction of shear strength of the soil (quicksand-like conditions). Typically, recent Holocene-age deposits with shallow groundwater table are susceptible to liquefaction.

Cohesive soils typically do not liquefy but can lose strength due to ground shaking under certain conditions.

We performed liquefaction analyses using the subsurface information collected from the exploratory borings. We assumed a groundwater depth of 5 feet in our analyses. Based on our analyses, the surficial loose to medium dense sand layer can potentially liquefy, and we estimate 1½ to 3 inches of seismically-induced settlement. We identified potential liquefiable layers in borings B-2 and B-3; however, these borings were drilled to only 16 and 11 feet bgs, respectively. Although we do not have the subsurface information below the boring depths, based on subsurface conditions encountered in boring B-1, the soil below the explored depth is expected to be primarily soft cohesive soils that are not liquefiable but have the potential for cyclic softening.

104644-001 October 20, 2020

The cohesive soils beneath the site is highly plastic and not susceptible to liquefaction.

However, because of high Liquidity Index (close to or greater than 1), soil can lose significant strength during a design seismic event. Liquidity Index (LI) is defined as

𝐿𝐿𝐿𝐿 =

𝑤𝑤𝑛𝑛 − 𝑃𝑃𝐿𝐿

𝐿𝐿𝐿𝐿 − 𝑃𝑃𝐿𝐿

where wn is the natural water content, PL and LL are plastic and liquid limits, respectively.

According to Idriss and Boulanger (2008), the shear strength of the soil can reduce by a factor of 8 to 10.

6.4 Expansive Soil Conditions

Some fine-grained soils undergo volume change when highly plastic particles interact with water. These expansive soils may swell when saturated with water and shrink when dried.

This phenomenon generally decreases in magnitude with increasing confining pressure.

These volume changes may damage lightly loaded shallow foundations and shallow improvements. The results of the Expansion Index test performed on one sample of elastic silt from the site indicate an Expansion Index (EI) of 101, indicating a high expansion potential. Based on the exploratory borings, this expansive soil layer occurs at a depth of 5 feet or more and below groundwater. For this condition we do not anticipate the building to be affected by the presence of expansive soil.

6.5 Soil Corrosion Potential

We submitted one soil sample to Sunland Analytical of Rancho Cordova, California, for analytical testing to evaluate the potential for corrosive attack on buried metals and reinforced concrete. Tests include pH, minimum resistivity, and chloride and sulfate concentrations. Results of the corrosion testing are included in Appendix B and summarized in Exhibit 6-2 below.

Exhibit 6-2:: Corrosion Testing Results

Boring No.

Sample Depth

(ft) pH Minimum Resistivity

(ohm-cm x 1,000) Chloride

(ppm) Sulfate (ppm)

B-2 5.8 7.42 2.04 1.6 2.6

NOTES:

ft = feet ohm-cm = ohm centimeter ppm = parts per million

The California Department of Transportation (Caltrans) considers a site to be corrosive to foundation elements if one or more of the following conditions exist: chloride concentration

104644-001 October 20, 2020 greater than or equal to 500 parts per million (ppm), sulfate concentration greater than or equal to 1,500 ppm, or pH of 5.5 or less (Caltrans, 2018a). The corrosivity test results suggest that the site soils are not corrosive to exposed buried metal or reinforced concrete.

6.6 Foundation Design

In our opinion, shallow continuous strip foundations should be suitable to support the proposed single-story structure provided mitigation measures described here are implemented. As described earlier, the site could experience seismically-induced settlement on the order of 1½ to 3 inches. The building is also likely to experience primary and secondary consolidation settlement under static condition. We evaluated the effect of potential loss of strength of the silt layer during a seismic event and concluded that bearing capacity of the footing will not be affected.

The mitigation measures described below would not reduce the magnitude of seismically-induced settlement or long-term secondary consolidation settlement but reduce the potential for differential settlement across the building. In the following sections, we provide our recommendations for foundation mitigation measure, allowable bearing pressure and lateral resistance for the foundation and our estimate for foundation settlement.

6.6.1 Mitigation Measure

We recommend the following mitigation measures to reduce differential settlement across the building arising from seismically-induced settlement or long-term secondary consolidation settlement:

Overexcavate the upper 2½ feet of soil below the proposed foundation subgrade elevation. The overexcvation should extend 3 feet beyond the exterior edge of the foundation.

Place a layer of geogrid (Tensar TX140 or equivalent) at the bottom of excavation.

If the excavated subgrade is disturbed, scarify upper six inches of the excavated surface and recompact to 90 percent of the maximum dry density determined by the ASTM D 1557 standard before placing geogrid.

Backfill over the first geogrid layer with a 1-foot-thick layer of aggregate base (AB) compacted to 95 percent of the maximum dry density determined by the ASTM D 1557 standard. AB should conform to Caltrans Class 2 AB as described in Section 26 of Caltrans Standard Specifications (Caltrans, 2018b).

Place a second layer of geogrid above the AB layer, 104644-001 October 20, 2020

Backfill to final footing and slab subgrade elevation with compacted AB as described above.

The proposed foundations and slab on grade could be supported on the compacted AB layer. A representative from Shannon & Wilson should be on site to observe the prepared subgrade before placing the first layer of geogrid, placement of geogrid and compaction of

AB.

6.6.2 Allowable Bearing Pressure

Allowable bearing pressure is a function of footing, shape, size, and tolerable settlement.

For design of the foundation, we recommend using an allowable bearing pressure of 600 pounds per square foot (psf) under static loading (dead plus live load) to limit foundation settlement to 1 inch or less, provided the footing width is 3 feet or less. For transient loading, the allowable bearing pressure may be increased by 30%.

Our additional recommendations related to footing design include the following:

According to Siskiyou County Building Department a minimum frost depth of 12 inches should be considered. We recommend a minimum footing embedment depth of 1.5 feet below adjacent grade. We do not recommend an embedment greater than 2 feet to avoid loading the underlying the soft soil.

Continuous footings should have a minimum width of 24 inches.

Continuous footings should be properly reinforced to allow the foundations to span isolated soil irregularities and anticipated differential settlement as described in the next section. The project structural engineer should determine the need for reinforcement based on anticipated structural loads.

6.6.3 Settlement

Foundation loading induces settlement in the underlying very soft to soft elastic silt. The magnitude of settlement will depend on the loading intensity and compressibility of the soil. Soil settlement is generated from three sources: immediate, primary consolidation, and secondary consolidation. Immediate settlement occurs by elastic deformation of the subsurface soil due to structure, embankment, or other imposed loading. Elastic settlement typically occurs rapidly as load is placed. Primary consolidation settlement consists of soil deformation that occurs in saturated fine-grained soils as excess porewater pressure generated by surface loading dissipates over time. Secondary compression settlement consists of long-term deformation of soil that is independent of the loading. This settlement extends over years or decades depending on soil properties.

104644-001 October 20, 2020

As mentioned earlier, we anticipate about 1 inch of settlement due to primary consolidation.

Primary consolidation settlement is expected occur over a period of 6 to 7 years. Additional secondary consolidation settlement on the order of 1 to 3 inches is anticipated over a building design life of 50 years. We recommend that the building be designed for a differential settlement of 1 inch across the building to account for consolidation settlement and additional 1 inch to account for liquefaction-induced settlement. We also recommend that utilities entering the building should accommodate up to 3 inches of relative movement.

6.6.4 Lateral Resistance

Resistance to lateral forces caused by wind, seismicity, unbalanced earth pressures, or other forces could be provided by passive earth pressures acting against the embedded portion of foundations and frictional resistance against the base of foundations.

We recommend a coefficient of friction of 0.6 be used between cast-in-place concrete and compacted AB for calculating the resistance to sliding at the base of the footings. Passive resistance on the embedded portion of the footing could be estimated using an equivalent fluid weight of 450 pounds per cubic foot. Passive resistance for foundations should be ignored in the upper 1 foot due to possible soil disturbance.

The estimated frictional and passive resistance values are ultimate value. These two modes of resistance should not be added unless the frictional component is reduced by 50%, because full mobilization of the passive resistance requires some horizontal displacement, which significantly decreases the frictional resistance.

6.7 Slab-on-Grade Floors

The slab-on-grade for the proposed building can be supported on compacted aggregate base prepared as described in Section 6.6.1. A capillary break should be provided under interior floor slabs, especially if moisture-sensitive floor coverings will be used. The capillary break should consist of at least 4 inches of clean, crushed rock or gravel placed beneath the slab.

The crushed rock or gravel layer should be graded such that all particles pass a 1-inch sieve with no materials passing the No. 4 sieve. A plastic water vapor retarder with a minimum 10-mil thickness should be placed directly over the gravel layer. The vapor retarder should meet the standards specified in ASTM E 1745.

Slab reinforcement and joint spacing should be designed by the structural engineer. We recommend using a modulus of subgrade reaction (ks) of 80 pounds per cubic inch for designing the interior floor slabs. Temporary loads exerted on the slab, such as construction

104644-001 October 20, 2020 vehicle traffic, cranes, forklifts, and storage of palletized construction materials, should be considered in the design of the slab.

6.8 Pavement Design

We understand the proposed parking area and access roads will be surfaced with asphalt concrete (AC) pavement. The proposed pavement will support passenger vehicles and tour bus traffic. Currently, we do not have traffic information. Based number of yearly visitors provided to us and certain assumptions on types of vehicles, we estimated a Traffic Index (TI) of 5 for a design life of 20 years.

Flexible pavement section design is based on the anticipated traffic loading, design life, and R-value of the subgrade. Blackburn Consulting, under subcontract to Shannon & Wilson, completed a R-value test (CTM 301) on a bulk sample of the subgrade soil. The test result indicates an R-value of 71. For pavement design, Caltrans limits the maximum R-value of subgrade to 50. We conservatively used a R-value of 40 in our analysis.

Based on a design R-value of 40 and a TI of 5, we recommend that the pavement structural section consist of 3 inches of AC over 4 inches of AB in accordance with Caltrans method for flexible pavement design. If the anticipated traffic loading is greater than our assumed value, we should be informed to revise our recommendations.

Long-term pavement performance will depend upon uniform and adequate compaction of soil subgrade, all fill within the pavement limits and AB. Additional recommendations for pavement construction are included in Section 7.3.2.

7 CONSTRUCTION CONSIDERATIONS

7.1 General

The applicability of the design recommendations presented in this report depends on the quality of construction practices used on this Project. The following sections present construction recommendations that should be considered and implemented

7.2 Site Preparation

Before fill is placed or foundations constructed, the site must be prepared. Prior to site grading, construction areas should be cleared of existing surface and subsurface structures, including foundations, concrete and pavement, utility poles, fence poles, underground utilities, vegetation, and other deleterious debris. Debris from the stripping should not be

104644-001 October 20, 2020 used as fill and should be disposed. Existing utilities that are not relocated will require protection against surface loads from construction equipment.

7.3 Subgrade Preparation

7.3.1 Building Subgrade

As mentioned earlier in Section 6.6.1, we recommend overexcavating upper 2½ feet of soil below the footing subgrade elevation under the entire building footprint. Overexcavation should extend 3 feet beyond the exterior edge of the outer most foundation. The exposed subgrade should be examined and should be cleaned of all deleterious materials. We strongly recommend maintaining the excavated surface in an undisturbed condition. If the subgrade is disturbed, we recommend the upper 6 inches of exposed subgrade be scarified and compacted to at least 90 percent of the maximum dry density determined by the ASTM D 1557 standard. A Shannon & Wilson representative should evaluate the prepared subgrade to confirm suitable bearing conditions prior to placement of geogrid and AB backfill as described in Section 6.6.1. The presence of the underlying soft cohesive soil may pose some construction difficulties in which case we recommend placing a 4-inch thick layer of compacted AB over the first geogrid layer to provide a stable working surface.

7.3.2 Subgrade for Pavement and Driveway

The upper 12 inches of pavement subgrades should be processed and uniformly compacted after the completion of underground utility construction and prior to the placement of AB to a relative compaction of 95%, as determined by ASTM D1557. Pavement subgrades should be proof-rolled with a fully loaded water truck (or equivalent) to evaluate the stability of the subgrades in the presence of our representative.

7.4 Materials for Fill

The on-site sandy soil is suitable as backfill. However, due to the presence of soft, compressible elastic silt beneath sand, we do not recommend placing additional fills to raise the current grade because the fill loads would induce additional settlement.

7.5 Fill Placement

Any required fill should be placed in loose lifts not more than 8-inches-thick and compacted. The fill should be compacted to at least 95 percent relative compaction ASTM Designation D1557 method of compaction.

104644-001 October 20, 2020

7.6 Pavement

The following sections present recommendations for the pavement section materials.

7.6.1 Aggregate Base

Pavement Aggregate Base (AB) material should conform to requirements of Class 2 AB as described in Section 26 of Caltrans Standard Specifications (Caltrans, 2018b). The AB should be placed in 6- to 8-inch-thick loose lifts and uniformly compacted to a relative compaction of at least 95%, as determined in accordance with ASTM D1557.

7.6.2 Asphalt Concrete

We recommend that Asphalt Concrete (AC) mix design be in accordance with Type A hot-mix asphalt, as described in Section 39 of the Caltrans’ Standard Specifications (Caltrans, 2018b) with lift thickness between 2 and 3 inches. The binder selection should be based on the anticipated pavement temperatures, traffic patterns, and local availability. A tack coat should be placed between subsequent lifts if the underlying lift will be used for traffic or left uncovered.

7.7 Dewatering

Deep excavations are not anticipated for the project. However, based on available information, groundwater at the site could be within 5 feet bgs depending on the season and may require temporary dewatering. We anticipate that groundwater in shallow excavations can be controlled by sumps and sump pumps. Dewatering and maintaining a stable excavation should be the Contractor’s responsibility.

7.8 Wet-Weather Considerations

Wet weather generally begins about mid-October and continues through about May, although rainy periods may occur at any time of year. Saturated soil will require a period of drying and aeration to reduce the moisture content of the soil to allow for the proper degree of compaction. Construction activities performed during wet weather could be hampered by high soil moisture content. As the compaction of structural fill is important for the preparation of the building foundation and pavements, it is advisable to schedule earthwork in dry weather conditions. Most of the surface soil at the site contains sufficient fines that may become difficult or impossible compact if the moisture content exceeds the optimum.

Performing earthwork during dry weather would reduce these problems and costs associated with rainwater and handling of wet soil. However, should wet-weather/wet-condition earthwork be unavoidable, the following recommendations are provided:

104644-001 October 20, 2020

The ground surface in and surrounding the construction area should be sloped to promote runoff of precipitation away from work areas and to prevent ponding of water.

Work areas should be covered with plastic. The use of sloping, ditching, sumps, dewatering, and other measures should be employed as necessary to permit proper completion of the work.

Earthwork should be accomplished in small sections to reduce exposure to wet conditions. That is, each section should be small enough so that the removal of unsuitable soil and placement and compaction of clean structural fill could be accomplished on the same day. The size of construction equipment might have to be limited to prevent soil disturbance. It might be necessary to excavate soil with a backhoe, or equivalent, so that equipment does not traffic over the constructed area.

Thus, subgrade disturbance caused by equipment traffic will be reduced.

No soil should be left uncompacted and exposed to moisture. A smooth-drum roller, or equivalent, should roll the surface to seal out as much water as possible.

In-place soil or fill soil that becomes wet and unstable and/or too wet to suitably compact should be removed and replaced with clean, granular soil.

Excavation and placement of structural fill material should be observed on a full-time basis by Shannon & Wilson to evaluate if the work is being accomplished in accordance with the Project specifications and our recommendations.

Grading and earthwork should not be accomplished during periods of heavy, continuous rainfall.

The above recommendations apply for all weather conditions, but most important for wet-weather earthwork. They should be incorporated into the contract specifications.

8 LIMITATIONS

This report was prepared for the exclusive use of DOWL, the U.S. Fish and Wildlife Service, and other members of the design team for specific application to this Project. The data and report should be provided to the contractors for their information, but our report, conclusions, and interpretations should not be construed as a warranty of subsurface conditions included in this report. The analyses, conclusions, and recommendations contained in this report are based on site conditions as they presently exist and further assume that the explorations are representative of the subsurface conditions throughout the site; that is, the subsurface conditions everywhere are not significantly different from those disclosed by the explorations. If subsurface conditions different from those encountered in the explorations are encountered or appear to be present during construction, we should be advised at once so that we can review these conditions and reconsider our recommendations, where necessary. If there is a substantial lapse of time between the

104644-001 October 20, 2020 submission of this report and the start of construction at the site, or if conditions have changed because of natural forces or construction operations at or adjacent to the site, we recommend that we review our report to determine the applicability of the conclusions and recommendations.

Within the limitations of scope, schedule, and budget, the analyses, conclusions, and recommendations presented in this report were prepared in accordance with generally accepted professional geotechnical engineering principles and practice in this area at the time this report was prepared. We make no other warranty, either express or implied. The conclusions and recommendations were based on our understanding of the Project as described in this report and the site conditions as observed at the time of our explorations.

Unanticipated soil conditions are commonly encountered and cannot be fully determined by merely taking soil samples from test borings. Such unexpected conditions frequently require that additional expenditures be made to attain a properly constructed project.

Therefore, some contingency fund is recommended to accommodate such potential extra costs.

The scope of our present work did not include environmental assessments or evaluations regarding the presence or absence of wetlands or hazardous or toxic substances in the soil, surface water, groundwater, or air on, below, or around this site or for the evaluation or disposal of contaminated soils or groundwater should any be encountered.

Shannon & Wilson has prepared the document, “Important Information About Your Geotechnical/Environmental Report,” to help you and others in understanding the use and limitations of this report.

9 REFERENCES

American Society of Civil Engineers, 2016, Minimum Design Loads and Associated Criteria for Buildings and Other Structures, Version 7-16.

ASTM International (ASTM), 2019, Annual book of standards, construction, v. 4.08, Soil and Rock (I): D 420 – D 5876: West Conshohocken, Penn., ASTM International.

ASTM International (ASTM), 2019, Annual book of standards, construction, v. 4.11, Building Constructions (I): E 72 – E 2166: West Conshohocken, Penn., ASTM International.

California Department of Transportation (Caltrans), 2018a, Corrosion guidelines (ver. 3.0):

Sacramento, California.

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California Department of Transportation (Caltrans), 2018b, Standard Specifications:

Sacramento, California.

California Department of Transportation (Caltrans), 2017, Highway Design Manual:

Sacramento, California, 6th ed.

California Building Code, Title 24, California Code of Regulations, California Building Standards Commission, 2019.

Donnelly-Nolan, J.M., and Champion, D.E., 1987, Geologic Map of Lava Beds National Monument, Northern California: U.S. Geological Survey Miscellaneous Investigations Series Map I-1804, 1 sheet, scale 1:24,000.

Gay, T.E., and Aune, Q.A., 1958, Geologic Map of California—Alturas sheet: California Division of Mines and Geology Regional Geologic Map GAM-001, scale 1:250,000.

Idriss, I. M. and Boulanger, R. W., 2008, Soil Liquefaction During Earthquakes, EERI Publication, Monograph MNO-12, Earthquake Engineering Research Institute, Oakland.

Sacramento

CALIFORNIA

Project

Location

Los Angeles

San Francisco

VICINITY MAP

PROJECT

LOCATION

(SEE INSET)

US Fish and Wildlife

Tulelake NWR

Tulelake, California

Aerial imagery downloaded from Google Earth Pro on 7-14-20.

October 2020 104644-001

F i l e n a m e

F

J S

A C

F i g

V i c i n i t y

M a p d w g

D a t e o g i n

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A C

20,000 40,000

Scale in Feet

FIG. 1

Tulelake

Klamath Falls

Midland

Dorris

Tulelake

Hatfield

Merrill

Canby Cross

Altamont

Pine Grove

M a t n e y

R d

K l a m a t h

F l l s

M a i n

H y

State Line Rd

C a l i f o r n i y

L a v

B e d s y

T e l l e s

S o u th s id e E x p y

K l a m a

F l l s

L a k e v i e

H w y w

H a t f i e l y

H i l l

R d

N Dike Rd West Side

H i l l

R

1" = 1000 Ft.

B-3

B-2

B-1

SITE AND EXPLORATION PLAN

US Fish and Wildlife

Tulelake NWR

Tulelake, California

October 2020 104644-001

60 120

Scale in Feet

FIG. 2

B-1

Boring Designation and

Approximate Location

LEGEND

NOTE

Figure adapted from client file 2020-06-19 -

USFWS-HQ - Tutlelake CA - Concept 1C.pdf .

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Appendix A: Subsurface Ex plorations

Appendix A

Subsurface Explorations

CONTENTS

A.1 General

A.2 Drilling

A.3 Soil Sampling

A.3.1 Standard Penetration Tests

A.3.2 Modified California (MC) Sampler

A.3.3 Bulk Samples

A.4 Groundwater Observations

A.5 References

Figures Figure A-1: Soil Description and Log Key (3 sheets) Figure A-2: Log of Boring B-1 (3 sheets) Figure A-3: Log of Boring B-2 (2 sheets) Figure A-4: Log of Boring B-3 (1 sheet)

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A.1 GENERAL

The subsurface exploration program for the Project consisted of the drilling and sampling of 3 borings, designated B-1, B-2, and B-3. Figure 2 of the main report shows approximate boring locations. Boring logs are presented in Figures A-2 through A-4. A key to soil descriptions and boring logs is presented in Figure A-1.

A.2 DRILLING

We retained Taber Drilling of West Sacramento, California to perform the borings. Prior to drilling, we marked each boring location and notified Underground Service Alert for utility conflicts. We obtained permits from the Siskiyou County Environmental Health Division.

Borings were drilled on July 1, 2020 with a truck-mounted drill rig. Solid-stem auger was used until groundwater was encountered, after which mud-rotary equipment was used to complete the boring. Boring B-1, B-2, and B-3 were drilled to depths of 51.5 feet, 21.5 feet, and 11.5 feet below ground surface, respectively.

A representative from Shannon & Wilson (S&W) observed drilling operations, logged the borings, retrieved representative soil samples for laboratory testing, and prepared logs of the explorations. On completion of drilling, the borings were backfilled with neat cement grout. John Fitzgerald of Siskiyou County observed backfilling of Boring B-1.

A.3 SOIL SAMPLING

Soil samples were collected during the subsurface explorations at selected depths using Standard Penetration Test (SPT) split-spoon sampler. A Modified California (MC) sampler was used at a select location to collect relatively undisturbed samples. The type and depth of the sampling are indicated on the boring logs.

A.3.1 Standard Penetration Tests

SPTs were performed in the borings at selected depths in general accordance with ASTM Designation: D 1586, Standard Method for Penetration Testing and Split-barrel Sampling of Soils (ASTM, 2019). The SPT consists of driving a 2-inch outside diameter, split-spoon sampler a distance of 18-inches into the bottom of the borehole with an automatic 140-pound hammer falling 30-inches. The number of blows required to achieve each three 6-inch increments of sampler penetration is recorded and the number of blows required for the last 12-inches of penetration is termed the Standard Penetration Resistance (N-value).

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The N-value is an empirical parameter that provides a means for evaluating the relative density, or compactness, of granular soils and the consistency, or stiffness, of cohesive soils.

The N-values are plotted on the boring logs.

The SPT samplers used during the penetration testing recovered disturbed samples of the soil, which were field classified and recorded on the logs by our field representative. The samples were collected in plastic jars and sealed to preserve the moisture in the sample. At the completion of our subsurface exploration, samples were taken to our laboratory for review and testing. Refer to Appendix B for laboratory testing and results.

A.3.2 Modified California (MC) Sampler

One MC sample was collected in general accordance with ASTM Designation: D 3550, Thick Wall, Ring-Lined, Split Barrel, Drive Sampling of Soils (ASTM, 2019). The MC is similar to the SPT but with larger outer (3-inch) and lined inner (2.4-inch) sampler diameters. Similar to SPT, the sampler is driven 18-inches using a 140-pound hammer falling 30 inches. The lined MC sample collected in the field was classified and sealed with plastic caps by our field representative and returned to our laboratory for review and testing. Refer to Appendix B for laboratory testing and results.

A.3.3 Bulk Samples

In addition to SPTs and MC, bulk samples were collected drill cuttings of near surface soils.

The approximate depth range that the samples were retrieved was estimated and noted on the boring logs. The bulk soil samples were field described and recorded on the logs by our field representative and returned to our laboratory for testing. Refer to Appendix B for laboratory testing and results.

A.4 GROUNDWATER OBSERVATIONS

We observed groundwater in borings B-1 and B-2 during drilling at depths of 6 and 5 feet below ground surface, respectively. Groundwater observations are noted on our boring logs. Please see main text for additional discussion.

A.5 REFERENCES

ASTM International, 2019, Annual Book of Standards, Construction, v 4.08, Soil and Rock (I); D 1586: West Conshohocken, PA, ASTM International, 1 v.

October 2020 104644

US Fish and Wildlife Tulelake NWR

Tulelake, California

1Gravel, sand, and fines estimated by mass. Other constituents, such as organics, cobbles, and boulders, estimated by volume.

2Reprinted, with permission, from ASTM D2488 - 09a Standard Practice for Description and Identification of Soils (Visual-Manual Procedure), copyright ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428.

A copy of the complete standard may be obtained from ASTM International, www.astm.org.

140 pounds with a 30-inch free fall.

Rope on 6- to 10-inch-diam. cathead 2-1/4 rope turns, > 100 rpm

NOTE: If automatic hammers are used, blow counts shown on boring logs should be adjusted to account for efficiency of hammer.

10 to 30 inches long Shoe I.D. = 1.375 inches Barrel I.D. = 1.5 inches Barrel O.D. = 2 inches

Sum blow counts for second and third 6-inch increments.

Refusal: 50 blows for 6 inches or less; 10 blows for 0 inches.

RELATIVE

CONSISTENCY

N, SPT,

BLOWS/FT.

5% to 12% fine-grained:

with Silt or with Clay 3

15% or more of a second coarse-grained constituent:

with Sand or with Gravel 5

< 5%

5 to 10%

15 to 25%

30 to 45%

50 to 100%

Surface Cement Seal

Asphalt or Cap

Slough

Inclinometer or Non-perforated Casing

Vibrating Wire Piezometer

N, SPT,

BLOWS/FT.

< 4 4 - 10

10 - 30 30 - 50

> 50

DESCRIPTION

< #200 (0.075 mm = 0.003 in.)

#200 to #40 (0.075 to 0.4 mm; 0.003 to 0.02 in.)

#40 to #10 (0.4 to 2 mm; 0.02 to 0.08 in.)

#10 to #4 (2 to 4.75 mm; 0.08 to 0.187 in.)

SIEVE NUMBER AND/OR APPROXIMATE SIZE

#4 to 3/4 in. (4.75 to 19 mm; 0.187 to 0.75 in.)

3/4 to 3 in. (19 to 76 mm)

3 to 12 in. (76 to 305 mm)

> 12 in. (305 mm)

Fine Coarse

Fine Medium Coarse

BOULDERS

COBBLES

GRAVEL

FINES

SAND

Sheet 1 of 3

CONSTITUENT2

SOIL DESCRIPTION

AND LOG KEY

SHANNON & WILSON, INC.

Geotechnical and Environmental Consultants

Absence of moisture, dusty, dry to the touch

Damp but no visible water

Visible free water, from below water table

FIG. A-1

Shannon & Wilson, Inc. (S&W), uses a soil identification system modified from the Unified Soil Classification System (USCS). Elements of the USCS and other definitions are provided on this and the following pages. Soil descriptions are based on visual-manual procedures (ASTM D2488) and laboratory testing procedures (ASTM D2487), if performed.

STANDARD PENETRATION TEST (SPT)

SPECIFICATIONS

Hammer:

Sampler:

N-Value:

Dry

Moist

Wet

MOISTURE CONTENT TERMS

Modifying (Secondary)

Precedes major constituent

Major

Minor Follows major constituent

1All percentages are by weight of total specimen passing a 3-inch sieve.

2The order of terms is: Modifying Major with Minor.

3Determined based on behavior.

4Determined based on which constituent comprises a larger percentage.

5Whichever is the lesser constituent.

COARSE-GRAINED

SOILS

(less than 50% fines)1

NOTE: Penetration resistances (N-values) shown on boring logs are as recorded in the field and have not been corrected for hammer efficiency, overburden, or other factors.

PARTICLE SIZE DEFINITIONS

RELATIVE DENSITY / CONSISTENCY

Sand or Gravel 4

30% or more coarse-grained:

Sandy or Gravelly 4

More than 12% fine-grained:

Silty or Clayey 3

15% to 30% coarse-grained:

with Sand or with Gravel 4

30% or more total coarse-grained and lesser coarse-grained constituent is 15% or more:

with Sand or with Gravel 5

Very soft Soft Medium stiff Stiff Very stiff Hard

Very loose Loose Medium dense Dense Very dense

RELATIVE

DENSITY

FINE-GRAINED SOILS

(50% or more fines)1

COHESIVE SOILS

< 2 2 - 4 4 - 8

8 - 15 15 - 30

> 30

COHESIONLESS SOILS

Silt, Lean Clay, Elastic Silt, or

Fat Clay 3

PERCENTAGES TERMS 1, 2

Trace

Few

Little

Some

Mostly

WELL AND BACKFILL SYMBOLS

Bentonite Cement Grout

Bentonite Grout

Bentonite Chips

Silica Sand

Perforated or Screened Casing

S&W INORGANIC SOIL CONSTITUENT DEFINITIONS

S O

IL

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Tulelake NWR

Tulelake, California

GC

SC

Inorganic

Organic

(more than 50% of coarse fraction retained on No. 4 sieve)

MAJOR DIVISIONS GROUP/GRAPHIC

SYMBOL

CH

OH

ML

CL

TYPICAL IDENTIFICATIONS

Gravel

Sand

Silty Sand; Silty Sand with Gravel

Clayey Sand; Clayey Sand with Gravel

Clayey Gravel; Clayey Gravel with Sand

Sheet 2 of 3

Gravels

Primarily organic matter, dark in color, and organic odor

SW

(more than 12% fines)

Silts and Clays

Silts and Clays

(more than 50% retained on No.

200 sieve)

(50% or more of coarse fraction passes the No. 4 sieve)

(liquid limit less than 50)

(liquid limit 50 or more)

Organic

Inorganic

FINE-GRAINED

SOILS

SM

Sands

Silty or Clayey Gravel

Silt; Silt with Sand or Gravel; Sandy or Gravelly Silt

Organic Silt or Clay; Organic Silt or Clay with Sand or Gravel; Sandy or Gravelly Organic Silt or Clay

HIGHLY-

ORGANIC

SOILS

COARSE-

GRAINED

SOILS

OL

(less than 5% fines)

GW

Geotechnical and Environmental Consultants

SHANNON & WILSON, INC.

(less than 5% fines)

PT

FIG. A-1

(more than 12% fines)

MH

SP

GP

GM

Silty or Clayey Sand

Silty Gravel; Silty Gravel with Sand

(50% or more passes the No.

200 sieve)

SOIL DESCRIPTION

AND LOG KEY

Elastic Silt; Elastic Silt with Sand or Gravel; Sandy or Gravelly Elastic Silt

Fat Clay; Fat Clay with Sand or Gravel;

Sandy or Gravelly Fat Clay

Organic Silt or Clay; Organic Silt or Clay with Sand or Gravel; Sandy or Gravelly Organic Silt or Clay

Poorly Graded Sand; Poorly Graded Sand with Gravel

Well-Graded Sand; Well-Graded Sand with Gravel

Well-Graded Gravel; Well-Graded Gravel with Sand

Poorly Graded Gravel; Poorly Graded Gravel with Sand

Lean Clay; Lean Clay with Sand or Gravel; Sandy or Gravelly Lean Clay

Peat or other highly organic soils (see

ASTM D4427)

NOTES

1. Dual symbols (symbols separated by a hyphen, i.e., SP-SM, Sand with Silt) are used for soils with between 5% and 12% fines or when the liquid limit and plasticity index values plot in the CL-ML area of the plasticity chart. Graphics shown on the logs for these soil types are a combination of the two graphic symbols (e.g., SP and SM).

2. Borderline symbols (symbols separated by a slash, i.e., CL/ML, Lean Clay to Silt; SP-SM/SM, Sand with Silt to Silty Sand) indicate that the soil properties are close to the defining boundary between two groups.

IGNEOUS ROCK

SEDIMENTARY

ROCK

METAMORPHIC

ROCK

S O

IL

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NOTE: No. 4 size = 4.75 mm = 0.187 in.; No. 200 size = 0.075 mm = 0.003 in.

UNIFIED SOIL CLASSIFICATION SYSTEM (USCS)

(Modified From USACE Tech Memo 3-357, ASTM D2487, and ASTM D2488)

Tulelake NWR

Tulelake, California

SHANNON & WILSON, INC.

Geotechnical and Environmental Consultants

FIG. A-1

Sheet 3 of 3

SOIL DESCRIPTION

AND LOG KEY

Interbedded

Laminated

Fissured

Slickensided

Blocky

Lensed

Homogeneous

ATD

Diam.

Elev.

ft.

FeO gal.

Horiz.

HSA

I.D.

in.

lbs.

MgO mm

MnO

NA

NP

O.D.

OW

pcf

PID

PMT

ppm psi

PVC

rpm

SPT

USCS

qu

VWP

Vert.

WOH

WOR

Wt.

Crumbles or breaks with handling or slight finger pressure.

Crumbles or breaks with considerable finger pressure.

Will not crumble or break with finger pressure.

PLASTICITY2

CEMENTATION TERMS1

GRADATION TERMS

STRUCTURE TERMS1

ACRONYMS AND ABBREVIATIONS

Alternating layers of varying material or color with layers at least 1/4-inch thick;

singular: bed.

Alternating layers of varying material or color with layers less than 1/4-inch thick;

singular: lamination.

Breaks along definite planes or fractures with little resistance.

Fracture planes appear polished or glossy; sometimes striated.

Cohesive soil that can be broken down into small angular lumps that resist further breakdown.

Inclusion of small pockets of different soils, such as small lenses of sand scattered through a mass of clay.

Same color and appearance throughout.

Narrow range of grain sizes present or, within the range of grain sizes present, one or more sizes are missing (Gap Graded).