03_140R2024R0017_16_of_19_0003.pdf

Appendix B - Figures

Figure 1 : Location of Test Pits and Cross Section Parallel to San Joaquin River at RM 182

Figure 2 : Location of Drill Holes and Cross Section Perpendicular to San Joaquin River at RM 183.5

Figure 3: Cross Section Parallel to the San Joaquin River at RM 182 Figure 4: Cross Section Perpendicular to the San Joaquin River at RM 183.5

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Appendix D - Drilling Logs at RM 183.5

MW-10-130

MW-10-131

MW-10-132

MW-10-80

20233893.001A/STO24R163917_R3 Page ii of v February 7, 2024 © 2024 Kleinfelder Revised August 9, 2024

A Report Prepared for:

Mr. Logan Howard, PE United States Department of Interior US Bureau of Reclamation 2800 Cottage Way, E-1815 Sacramento, CA 95825

GEOTECHNICAL DATA REPORT

ARROYO CANAL FISH SCREEN AND SACK DAM FISH PASSAGE PROJECT

SAN JOAQUIN RIVER RESTORATION PROGRAM

FRESNO AND MADERA COUNTIES, CALIFORNIA

KENALL PROJECT 8090

KLEINFELDER PROJECT 20233893.001A

Prepared by:

Victoria Tinoco, EIT Jay Zlotkowski, PG Project Engineer Senior Geologist

Jose Asyn, PE (TX) Principal Engineer

Reviewed by:

James A. Wetenkamp, PG, CEG Steven J. Wiesner, PE, GE No. 3027 Senior Engineering Geologist Senior Principal Geotechnical Engineer

Rajesh Tolikonda, PE (TX) Project Manager

KLEINFELDER KENALL

2001 Arch-Airport Road, Suite 100 2500 West City Boulevard, Suite 700 Stockton, CA 95206 Houston, TX 77042 Phone: 209-948-1345 Phone: 832-251-8200

February 7, 2024 Revised August 9, 2024

20233893.001A/STO24R163917_R3 Page iii of v February 7, 2024

TABLE OF CONTENTS

SECTION PAGE

1 INTRODUCTION

1.1 BACKGROUND

1.2 PROJECT DESCRIPTION

1.2.1 Operations and Maintenance Building

1.2.2 Fish Screen

1.2.3 River Bypass

1.2.4 Fish Ramp

1.2.5 Fish Ladder

1.2.6 Upstream Berm

1.3 PROJECT TEAM

1.4 PURPOSE

1.5 CURRENT INVESTIGATION SCOPE

1.6 STUDY DATUMS AND COORDINATE SYSTEM

2 GEOLOGIC SETTING

2.1 REGIONAL GEOLOGY

2.2 AREA AND SITE GEOLOGY

2.3 REGIONAL FAULTS AND SEISMICITY

2.3.1 Regional Seismotectonic Setting

2.3.2 Regional Faulting

2.4 GEOMORPHOLOGY AND STRATIGRAPHY

2.5 SUBSIDENCE

3 CURRENT INVESTIGATION AND LABORATORY TESTING

3.1 CURRENT SUBSURFACE INVESTIGATION

3.1.1 General

3.1.2 Pre-Exploration Activities

3.1.3 Explorations

3.2 CURRENT LABORATORY TESTING

3.2.1 Moisture Content and Dry Unit Weight

3.2.2 Specific Gravity

3.2.3 Atterberg Limits

3.2.4 Grain Size Analyses

3.2.5 One Dimensional Consolidation Tests

3.2.6 Pinhole and Crumb Dispersion Tests

4 GEOLOGIC INTERPRETATION

4.1 SOIL GROUPINGS

4.2 GROUNDWATER

5 GEOTECHNICAL AND CONSTRUCTION CONSIDERATIONS

5.1 Excavation

5.2 Slope Stability

5.3 Groundwater

5.4 Other Considerations

6 LIMITATIONS

20233893.001A/STO24R163917_R3 Page iv of v February 7, 2024

7 REFERENCES

TABLES

2.1 Nearby Late Quaternary and Younger Faults

3.1 Summary of Current Investigations

4.1 Summary of Groundwater Measurements in Observation Wells for the Sack Dam Study

Area

4.2 Summary of Groundwater Conditions Calculated from Pore Pressure Dissipation Tests in CPTs for the Sack Dam Study Area

FIGURES

1-1 Project Vicinity Map 1-2 Proposed Improvement Plans 1-3 Exploration Location Map 2-1 Geologic Map 2-2 Fault Map 3-1 Geologic Cross Section Legend 3-2 Subsurface Profile A- 3-3 Subsurface Profile B-

APPENDIX

A Logs of Borings B Hammer Energy Measurement Reports C Cone Penetration Test Report D Laboratory Test Data

20233893.001A/STO24R163917_R3 Page v of v February 7, 2024

REPORT ACRONYMS

ASTM ASTM International, Inc.

bgs Below the ground surface BOR Bureau of Reclamation CCID Central California Irrigation District CGS California Geological Survey CPT Cone Penetration Test El. Elevation GDR Geotechnical Data Report HMRD Henry Miller Reclamation District ID Inner Diameter Mw Moment Magnitude Nf Field measured blow count NAD83 North American Datum of 1983 NAVD88 North American Vertical Datum of 1988 NTU Nephelometric Turbidity Unit OD Outer Diameter PPDT Pore Pressure Dissipation Test QFR Qualified Field Representative ROE Right-of-Entry sCPT Seismic Cone Penetration Test SNGV Sierra Nevada-Great Valley SOW Statement of Work SPT Standard Penetration Test UD Undisturbed USA Underground Service Alert North 811 USACE United States Army Corps of Engineers USGS United States Geological Survey

20233893.001A/STO24R163917_R3 Page 1 of 38 February 7, 2024

1 INTRODUCTION

1.1 BACKGROUND

The San Joaquin River Restoration Program (SJRRP) is a comprehensive, long-term effort lead by the United States Department of the Interior Bureau of Reclamation (BOR) to restore flows to the San Joaquin River from Friant Dam to the confluence of the Merced River and restore a naturally reproducing and self-sustaining Chinook salmon fishery in the river while reducing or avoiding adverse water supply impacts from Restoration Flows. The SJRRP is the direct result of the Stipulation of Settlement in NRDC, et al. v. Kirk Rodgers, et al. (Settlement), reached in

September 2006 by the U.S. Departments of the Interior and Commerce, the Natural Resources

Defense Council (NRDC), and the Friant Water Users Authority (FWUA). The Settlement, which followed an 18-year lawsuit, received federal court approval in October 20061.

Federal legislation, the San Joaquin River Restoration Settlement Act, was passed in March 2009 authorizing federal agencies to implement the Settlement. Directed by Title X of Public Law 111-

11, and noted in Paragraphs 11(a)(6) and 11(a)(7), the Settlement requires modifications at Sack

Dam and the Arroyo Canal to screen Arroyo Canal and ensure fish passage at Sack Dam.

The Settlement is based on two goals:

of the San Joaquin River below Friant Dam to the confluence of the Merced River, including naturally-reproducing and self-sustaining populations of salmon and other fish.

Water Management: To reduce or avoid adverse water supply impacts to all of the Friant

Division long-term contractors that may result from the Interim Flows and Restoration

Flows provided for in the Settlement.

1 See References Section under United States District Court, Eastern District of California (Sacramento

Division) (2006).

2 See References Section under United States Department of the Interior, Bureau of Reclamation (2023).

20233893.001A/STO24R163917_R3 Page 2 of 38 February 7, 2024

1.2 PROJECT DESCRIPTION

Sack Dam is located on the San Joaquin River, approximately 18 miles southeast of the town of

Los Banos, California and approximately 22 miles downstream from the Mendota Dam. The aim of the project is to provide fish passage around the existing Sack Dam, and screen fish from flows going into the Arroyo Canal. To meet these objectives, the BOR has designed a fish screen and a fish passage channel. In addition, the proposed headwork structures maintain the pool water surface elevation and allows for an additional 5 feet of subsidence. The features conveying flow around Sack Dam include a fish ladder, a fish ramp and a river bypass. Additional project objectives also include flow measurement, flow control, and adaptability to changing site conditions.

The original Sack Dam was a small structure of piled sacks placed in the river. The dam was later constructed as a more permanent wooden structure in 1929, and later was built in concrete in

1946. The dam is currently 100 feet long and has anchored concrete wing walls on both sides of the river. The dam includes 20 bays separated by concrete piers. Since its construction, Sack

Dam has experienced regional subsidence. The differential subsidence experienced by the dam required a deeper impoundment, and sheet piles have been placed around the sides of the dam for structural stability. We understand that the estimated subsidence for the dam, and in the area, is in the range of 0.2 to 0.3 feet per year, up to the maximum design subsidence of 5 feet3, as mentioned above.

The Arroyo Canal is located just upstream of Sack Dam on the left bank of the San Joaquin River.

The canal was historically a natural waterway called Temple Slough. The canal conveys water approximately 20 miles to the northwest, where it becomes part of the Santa Fe Canal near Los

Banos. The Poso Canal is also located on the left bank of the San Joaquin River and crosses over the mouth of the Arroyo Canal by a flume structure.

We understand that the existing top elevation of the San Joaquin River Levees in the area are at approximately El. + 130 feet; the existing maximum operational water surface elevation of the

Sack Dam is at approximately El. +124.3 feet; and the top of the downstream concrete slab of

Sack Dam is at approximately El. +116.6 feet. The proposed design water surface elevation is at

El. +121.3 feet, with water upstream of the fish screen requiring an elevation of El. +121.8 feet.

The elevations are referenced to the Central California Irrigation District Datum. The arroyo Canal

3 See References Section under United States Department of the Interior, Bureau of Reclamation (2023).

20233893.001A/STO24R163917_R3 Page 3 of 38 February 7, 2024

Fish Screen design high and low water surface elevations are El. +127 and El. +122.5 feet, respectively.

The following sections provide additional information regarding some of the project elements. In addition to the features described below, a log boom would be placed upstream of the fish screen to protect the structure from debris and vegetation. There are other features that will interfere with the project that will be addressed by others before the project construction, including the installation of a bridge over Poso Canal, relocation of an existing 6-inch PG&E gas line, removal of low powerlines, installation of a stream gauge station downstream on the river, and other communication components.

1.2.1 Operations and Maintenance Building

The Operations and Maintenance Building (O&M) will be a pre-engineered metal building designed to contain equipment storage, restroom and control room. The building is planned as a metal panel clad with standing seam roof with the interior portioned into both conditioned and unconditioned interior finish sides. A masonry wall enclosure with shade structure would be built adjacent to the O&M building to enclose power generation equipment and water storage tank. In addition, a septic tank without a leach field is also planned at this location.

We understand that the facility also includes a gravel surface yard, fencing, gates and a 35-foot foldable radio tower. We also understand that a new bridge across Poso Canal to the proposed

O&M Building will be constructed by others.

1.2.2 Fish Screen

The proposed fish screen is comprised of stainless-steel screens installed in guide slots on steel supports consisting of W-sections and welded angles. The fish screen and its steel supports will be anchored to a concrete base that spans approximately 380 feet in length, 10 feet wide, and

2 feet thick. The structure consists of two screened sections with thirty-three 5-foot fish screen panels each and two relief panels in the middle of each section. The fish screen structure foundation concept consists of driven circular steel piles beneath the concrete slab. Based on historic geotechnical data, a high likelihood of liquefaction is expected on granular soil layers in response to the 2,500-yr return period ground motions at the site. The concrete base also includes a driven sheet pile cut-off wall to help mitigate seepage and potential failures during seismic events.

20233893.001A/STO24R163917_R3 Page 4 of 38 February 7, 2024

The sides of the fish screen structure will be connected to the existing grade through concrete retaining wall abutments. Retaining walls have been designed to tie into the south bank of the

Arroyo Canal inlet and the proposed fish ladder downstream of the fish screen. Driven sheet pile retaining walls were selected along the southern bank. In addition, a metal walkway will be installed at the top of the fish screen structure for access.

1.2.3 River Bypass

The headworks structure is planned on the right bank of the San Joaquin River and east of Sack

Dam. The headworks design is a concrete structure with two 10-foot by 13-foot bottom hinged overshot gates, two 4.5-foot by 13-foot slide gates, and four 10-foot by 13-foot slide gates. A concrete deck across the top of the headworks structure provides access to the gates and a way across the San Joaquin River. The fish ladder and fish ramp are adjacent to this structure.

The headworks structure foundation consists of driven 18-inch circular steel piles beneath the concrete slab. The foundation piles would be spaced at approximately 11.5 feet, such that they are located directly beneath the interior and exterior walls of the headworks structure. As mentioned previously, there is a high likelihood that piles in this area would encounter liquefiable granular soil layers.

The proposed sides of the river bypass channel are cantilever retaining walls approximately

15 feet in height. The lining between the walls is concrete slightly sloped downstream. Stoplogs, guides and lifting beams are planned for the gate bays of the river bypass.

1.2.4 Fish Ramp

The fish ramp consists of a concrete headworks, a concrete transition structure, and a riprap trapezoidal channel. The concrete fish ramp structure includes four 4.5-foot by 13-foot slide gates.

The fish ramp requires the headworks features and channel to be designed to be able to be raised in one-foot increments to accommodate future subsidence. Stoplogs, guides and lifting beams are planned for the gate bays of the fish ramp.

1.2.5 Fish Ladder

A vertical slot ladder will provide passage for fish from downstream of the new headworks structure to upstream. The fish ladder entrance will tie into the low-flow channel on the left side of

20233893.001A/STO24R163917_R3 Page 5 of 38 February 7, 2024 the river bypass. The fish ladder will consist of eleven rows of baffles. Initially, the fish ladder will be constructed with six fully completed baffles; while the remaining five baffles could be completed as the site subsides. Stoplogs, guides and lifting beams are planned for the entrance and exit of the fish ladder structure.

1.2.6 Upstream Berm

To direct flow of the San Joaquin River through the new headworks and the bypass channel, a berm will be constructed on the upstream side of the existing Sack Dam structure. The berm would also block fish from entering the Arroyo canal during high river flows. The alignment will extend from the west bank of the San Joaquin River to the east bank, tie west retaining wall, and terminate at the fish ladder. The top of the berm elevation will match the existing adjacent levee top elevation and will have 6 inches of gravel surfacing. Side slopes will be 3:1 (H:V) and be protected with 18 inches of riprap on 15 inches of bedding. Along the west wall of the bypass channel, the berm crest will generally be 20 feet wide with some wider areas to allow for an O&M staging area and vehicle turning near the fish ladder.

1.3 PROJECT TEAM

The project team included staff from Kenall, Inc., Kleinfelder, and Geo-Ex Subsurface Exploration.

Kenall, Inc. provided overall project management and provided a quality review of all deliverables.

Kleinfelder provided the field staff and general oversight in the field. In addition, Kleinfelder conducted the majority of the laboratory testing and provided oversight of the subcontracted laboratories. Finally, Kleinfelder prepared this geotechnical data report (GDR). Geo-Ex

Subsurface Exploration conducted all of the subsurface explorations, including Standard

Penetration Test (SPT), intact sampling borings referred to as undisturbed or UD borings in this report, Cone Penetration Test soundings (CPTs), and installed the observation wells.

1.4 PURPOSE

The purpose of this GDR is to summarize the available geotechnical data obtained by the project team for the current subsurface investigation. The current investigation included SPTs and UDs, as well as performing CPTs including seismic CPTs (sCPTs), installing observation wells, and laboratory testing. Geotechnical data provided herein are subject to the provisions outlined in

Section 6.

20233893.001A/STO24R163917_R3 Page 6 of 38 February 7, 2024

1.5 CURRENT INVESTIGATION SCOPE

The project team performed a geotechnical field investigation within the Sack Dam study area within Reach 3, supplementing existing data from previous investigations. The current investigation is detailed in Section 3. The field exploration program consisted of drilling four SPT borings, four UD borings (which are companion holes to the SPTs), five CPTs, one sCPT, and installing four observation wells within the Sack Dam study area. This GDR provides a summary of the field explorations, subsurface logs, laboratory test results, and CPT data, completed within the Sack Dam study area for the current investigation.

Previous investigations performed by others were conducted within the Sack Dam study area but are not included in this report.

1.6 STUDY DATUMS AND COORDINATE SYSTEM

The vertical datum used for this study is the North American Vertical Datum of 1988 (NAVD88) using the GEOID03 model. The horizontal datum used for this study is the North American Datum of 1983 (NAD83) (1991.35 epoch). All elevations are provided in feet and are positive unless a negative sign (-) is included.

20233893.001A/STO24R163917_R3 Page 7 of 38 February 7, 2024

2 GEOLOGIC SETTING

2.1 REGIONAL GEOLOGY

The Sack Dam site is located in the central portion of the San Joaquin Valley, California (Figure

1-1). The San Joaquin Valley comprises the southern part of the 725 km long, 65 to 95 km wide, and up to 9 km deep Great Valley geomorphic province of California. The Great Valley is an asymmetrical synclinal trough with a gently dipping eastern limb that has been filled with upper

Mesozoic and Cenozoic sediments onto crystalline basement rocks of the southwestward tilted

Sierran block (Bartow, 1991). These deep alluvial deposits thin and terminate as the boundaries of the basin approach bedrock units of the Foothills Metamorphic Belt and Sierra Nevada granitic basement on the east, and sedimentary and mélange bedrock of the Coast Ranges on the west.

The buried Stockton arch and associated Stockton fault separate the San Joaquin sedimentary basin from the northern Sacramento basin. Cenozoic strata in the San Joaquin basin thicken south-southeastward from about 800 m in the north to over 9,000 m in the south (Bartow, 1991).

The Great Valley province is bounded on the west by the Coast Ranges Great Valley fold and thrust belt. This system includes a series of east-directed blind thrust faults (i.e., low-angle reverse faults that do not extend to the ground surface) beneath the western margin of the valley, where rocks of the Coast Ranges are being thrust up over Great Valley sediments (Wakabayashi and

Smith, 1994). East-directed thrusting over ramps in the detachment surface, along with overlying west-directed backthrusts have created a zone of crustal shortening along the eastern range front of the Coast Ranges (Unruh and Moores, 1992). Regional structural features along the western

Great Valley consist of north to northwest trending broad folds and underlying blind reverse faults.

The San Joaquin River is the main drainage feature of the region, flowing generally west-southwestward from Friant, California to north of Mendota, California, then north-northwestward to its discharge point into Suisun Bay in the San Francisco Bay area. Within the project area, the

San Joaquin River has been diverted into canal systems upstream of the Sack Dam (Arroyo

Canal) and upstream of the Mendota Dam (Poso canal).

20233893.001A/STO24R163917_R3 Page 8 of 38 February 7, 2024

2.2 AREA AND SITE GEOLOGY

The San Joaquin Valley floor is underlain with a thick sequence of Quaternary clastic continental deposits that are composed primarily of alluvial fan detritus from rivers draining the glaciated

Sierra Nevada to the east and the non-glaciated Coast Ranges to the west and south (Lettis and

Unruh, 1991). The alluvial fan deposits thicken towards the valley axis, where they interfinger with flood basin and lacustrine sediments (Lettis and Unruh, 1991).

The regional Geologic Map of the Santa Cruz Sheet, California, 1:250,000 (Jennings and Strand, 1958), prepared by the California Department of Natural Resources, Division of Mines, as well as the Geologic Map of the San Joaquin Valley, California, 1:500,000 (Page, 1986), prepared by the

U.S. Geological Survey (USGS), were reviewed. These sources respectively depict the Sack

Dam site and vicinity as being covered with Holocene age stream channel (Qsc) sediments and river deposits (Qr), which are consistent with the sand, silt, and minor amounts of clay observed in the project subsurface explorations. These predominately coarse-grained fluvial sediments deposited along the San Joaquin River channel are flanked on the east and west with Holocene age flood basin deposits (Qb), which consist of clay and silt with some sand. Fill material is located at the east and west abutments of Sack Dam. Embankment fill is located along east and west banks of the Poso Canal west of the Sack Dam site, as well as along the north and south banks of the Arroyo Canal southwest of Sack Dam.

A geologic map for the project (Figure 2-1) has been modified from Page (1986). Descriptions of the soils encountered are discussed in the Geologic Interpretations section below (Section 4.1) and detailed logs of borings are presented in Appendix A.

2.3 REGIONAL FAULTS AND SEISMICITY

2.3.1 Regional Seismotectonic Setting

The Sack Dam site is located in the Western United States in the transform plate boundary region between the Pacific Plate (relative northwest translation) and the North American Plate (see

Exhibit 1). The site lies within the Sierra Nevada-Great Valley (SNGV) block (also known as the

Sierra Nevada microplate), which generally is thought to act as an independent block that has tilted westward. The SNGV block is bounded on its eastern edge by a zone of faults known as the Walker Lane Belt beyond which is the crustal extensional region of the Basin and Range.

Further afield in the northwestern portion of the state and extending northward to the pacific

20233893.001A/STO24R163917_R3 Page 9 of 38 February 7, 2024 northwest, the Juan de Fuca plate is currently subducting beneath the North American plate in a region known as the Cascadia Subduction Zone (Humphreys and Coblentz, 2007; Unruh et al., 2003; Unruh and Humphreys, 2017).

Exhibit 1 Regional relative motions (GPS) and tectonic plate boundaries (UNAVCO.org, accessed 2019)

Regional stress buildup due to the northwestern movement of the Pacific Plate is primarily released through displacement along faults within the San Andreas fault system (e.g., San

Andreas fault, Hayward fault, etc.) and to a lesser extent by displacements along faults within the

Walker Lane Belt. East-west directed extensional stress due to the Pacific Plate wrenching on the

North American Plate has caused regional crustal thinning and the development of north-northwest trending normal faults within the Basin and Range (Fey and Humphreys, 2008; Field et al., 2013).

2.3.2 Regional Faulting

There are no active or potentially active faults in the immediate vicinity of the Sack Dam site, as evidenced by the lack of historic seismicity. The closest Quaternary age fault to the site is the inferred Kings Canyon lineament located approximately 14.5 miles to the north-northeast

(Jennings, 2010). The closest active fault to the site (i.e., showing evidence for fault displacement within the past 11,000 years, as defined by the California Geological Survey (CGS)), is the

Ortigalita fault zone located approximately 27.9 miles to the west-southwest (Jennings, 2010).

Site

20233893.001A/STO24R163917_R3 Page 10 of 38 February 7, 2024

Other significant active fault systems within proximity to the site include faults to the west within the San Andreas system (San Andreas fault zone, Quien Sabe fault, and Calaveras fault zone) and can be seen on Figure 2-2.

Significant Quaternary age faults within the Great Valley system of blind thrust faults located along the western edge of the San Joaquin Valley, and in proximity to the Sack Dam site, include the inferred and undifferentiated Quaternary age Laguna Seca section of the Great Valley fault (about

17.5 miles west-southwest), the Late Quaternary age San Joaquin fault (about 17.9 miles west-southwest) (USGS, 2023).

East of the site, active fault systems include the Kern Canyon fault, the Independence fault, the

Owens Valley fault zone, the White Mountains fault zone, the Round Valley fault, the Hilton Creek

Fault, as well as faults associated with crustal extension of the Basin and Range. Much further afield, the Cascadia subduction zone (northwest corner of the state) can generate very large magnitude events and may have potential to impact long period ground motions at the site.

Based on the Fault Activity Map of California (Jennings, 2010), prepared by CGS, as well as the

USGS Quaternary Fault Database (USGS, 2023), the nearest Late Quaternary faults, or younger, within a 50-mile radius from the site with evidence for fault displacement within the past 130,000 years are provided in Table 2.1. Estimated moment magnitude (MW) is provided by the USGS

Earthquake Scenario Map (BSSC, 2014). Additional fault sources with significant seismogenic sources should be considered for seismic source models used in future, site-specific seismic hazard evaluations.

Table 2.1 Nearby Late Quaternary and Younger Faults

Name Distance (mi) Magnitude (MW)

Great Valley Thrust Fault System2 17.5 W-SW 6.57

San Joaquin Fault1 17.9 W-SW -

1 20.2 W-SW -

Ortigalita Fault Zone1 27.9 W-SW 7.01

Great Valley Thrust Fault System3 37 W-NW 6.92

20233893.001A/STO24R163917_R3 Page 11 of 38 February 7, 2024

Name Distance (mi) Magnitude (MW)

Quien Sabe Fault1 42 W-SW 5.61

Great Valley Thrust Fault System4 44 S-SE 7.03

San Benito FZ-Paicines Flt-Calaveras Flt1 45.1 W-SW 7.26

San Andreas Fault System1 46.4 W-SW 7.15

Bear Valley Fault1 46.9 SW - 1 Closest distance to mapped surface trace of Late Quaternary and younger faults from the Fault Activity Map of California (Jennings, 2010).

2 Inferred Laguna Seca section of the Great Valley thrust fault system (USGS, 2023).

3 Inferred Orestimba section of the Great Valley thrust fault system (USGS, 2023).

4 Inferred Coalinga section of the Great Valley thrust fault system ruptured historically during the 1983 Coalinga earthquake (USGS, 2023).

2.4 GEOMORPHOLOGY AND STRATIGRAPHY

Within the project area, the late Quaternary geomorphology of the San Joaquin River is consistent with a graded river system, which is characterized by more side-to-side movements than down-cutting erosion. The lateral energy of a graded river causes synchronous erosion and deposition in sweeping bands commonly referred to as meanders. The outside of the meander is a zone of erosion. Material removed by the river at this zone is then deposited downstream as point bars in zones of decreased velocity on the inside of the subsequent meanders. In this way, the river migrates laterally across the flood plain. Point bar deposits tend to be composed of coarse-grained sediment as the flow velocity decreases and drops the larger particles of the load.

Often the erosion on the outside of a meander is slowed where the river encounters more resistant materials in the flood plain. This allows the next closest upstream meander to catch up and process as the higher energy flows can more easily cut a new thalweg (base of the active channel). The result of the conjoining meanders is the straightening of the river across the opening of the neck and the creation of an abandoned bend in the river, commonly referred to as an oxbow lake.

Flooding also results in the deposition of natural levee, overbank, and basin deposits, which are generally characterized by progressively finer grained sediments. Natural levee deposits are located adjacent to a main river channel and receive the first sediments deposited by an overflow event. Overbank deposits are located adjacent to the natural levee and are generally composed of fine sand and silt as the flood waters decrease in velocity as they progress further from the

20233893.001A/STO24R163917_R3 Page 12 of 38 February 7, 2024 main river channel. Basin deposits are generally composed of silt and clay as the flood waters slow to a stand-still and drop their remaining fine-grained load.

As discussed in Section 2.2, the mapped surficial geologic deposits consist of late Quaternary age river channel sediments consisting of sand, silt, and some clay. Similar deposits were encountered during the current subsurface investigation. The recent channel deposits in the near-subsurface generally consist of interbedded lenses and beds of coarse- and fine-grained sediments that pinch-out and grade into each other.

Details regarding the subsurface investigation are discussed in Section 3. The geologic interpretation of near-subsurface is discussed in the Section 4. Figure 2-1 provides a regional geologic map of the study area and vicinity. Figures 3-1 through 3-3 present subsurface profiles across the project area based on the current explorations.

2.5 SUBSIDENCE

within the San Joaquin Valley has caused groundwater levels to lower, aquifer-system compaction, and subsequent regional land subsidence and permanent aquifer-system storage loss (Brandt, 2018). By 1970, subsidence of more than 1 foot had affected more than 5,200 square miles of irrigable land within the San

Joaquin Valley, with the maximum subsidence of approximately 28 feet measured near Mendota, California (Poland et al., 1975). Since 1970, the regions with the most subsidence have shifted from the west San Joaquin Valley to the south portion of the valley near the towns of Pixley, Corcoran and Tulare, California (Smith, 2023).

To address future subsidence impacts to the proposed Arroyo Canal Fish Screen and Sack Dam

-Pacific Region Surveys and Mapping

Branch have implemented a subsidence monitoring program that aims to delineate the occurrence of subsidence, as well as establish relative rates of subsidence.

20233893.001A/STO24R163917_R3 Page 13 of 38 February 7, 2024

3 CURRENT INVESTIGATION AND LABORATORY TESTING

3.1 CURRENT SUBSURFACE INVESTIGATION

3.1.1 General

This section summarizes the subsurface investigation completed by the project team within the

Sack Dam study area. The investigation was completed to supplement previously obtained data and to support geotechnical analysis and design of project features.

The subsurface investigation program was performed as outlined in the Statement of Work (SOW) included with each task order and in general accordance with Chapters 3 and 11 of the BOR

Engineering Geology Field Manual (USBR, 1998). The SOW outlined the approximate exploration locations, sampling intervals, sample types, and exploration depths. The BOR developed the exploration program based on a review of proposed project features, previous explorations, reports, maps, geomorphologic data, topographic data, and other historical information.

3.1.2 Pre-Exploration Activities

Prior to drilling, Kleinfelder prepared a Health and Safety Plan (HASP) and obtained all necessary approvals as discussed below.

3.1.2.1 Health and Safety Plan

The project team prepared a site-specific HASP dated December 8, 2022. The HASP covered the subsurface explorations for the Mendota Pool Bypass and Reach 2B study area and was later applied to the Sack Dam study area.

3.1.2.2 Right-of-Entry

Right-of-Entry (ROE) for the Sack Dam study area explorations was obtained by BOR. To access the left bank (west side of the river) ROE was obtained from the Central California Irrigation District

(CCID) and the Poso Canal Company through a non-Federal CCID Entry Permit. The right bank of the river (east side) was The project

20233893.001A/STO24R163917_R3 Page 14 of 38 February 7, 2024 team coordinated with BOR and a Clayton Farms representative to obtain the required permits and approvals to access the planned subsurface exploration locations.

3.1.2.3 Utility Clearance

The project team visited each proposed exploration location and visually observed the presence of overhead utilities. Each proposed exploration location was marked with a wood stake as required by Underground Service Alert North 811 (USA). Kleinfelder notified USA a minimum of

48 hours in advance of drilling. In addition, Geo-Ex Subsurface Exploration of Dixon, California

(Geo-Ex) also notified USA, as required by state law. A USA ticket number, clearance date, expiration date, and extension date were obtained by both Kleinfelder and Geo-Ex.

In addition to the USA clearance activities, the project team utilized 1st Call Utility Locating of

Richmond, California to scan each proposed exploration location with ground penetrating radar equipment. Possible underground utilities were noted with spray paint and exploration locations were adjusted within the USA delineations to avoid conflict, as necessary.

3.1.2.4 NEPA, Biological, and Cultural Survey and Clearance

All required NEPA, biological, and cultural surveys were conducted by BOR and clearances obtained prior to subsurface exploration activities.

3.1.3 Explorations

A total of 18 subsurface explorations were completed as part of current exploration program. Five CPTs and one sCPT were advanced, four SPT and four companion

UD borings were drilled, and four observation wells were installed, as shown in Table 3.1 below.

Two CPTs and one sCPT were performed along the left bank of the river and advanced to depths between approximately 57.5 and 76 feet. Three CPTs were performed along the right bank of the river and advanced to depths between approximately 29 and 72 feet. Advancement of the CPTs was completed between August 28 through August 31, 2023. CPT plots are included in Appendix

C.

Two SPT borings were drilled along the left bank of the river to depths between approximately

71.5 and 76.5 feet. Two companion UD borings were advanced to depths of approximately 64.5

20233893.001A/STO24R163917_R3 Page 15 of 38 February 7, 2024 and 70 feet. Two companion observation wells were installed to depths of approximately 20 and

33 feet. Two SPT borings were drilled along the right bank of the river to a depth of approximately

76½ feet each, along with two companion UD borings advanced to depth of 70 and 75 feet, and two companion observation wells to depths between 15 and 26 feet. Observation well OW-23-

13a was initially installed with the screen at a depth of 20 to 40 feet below ground surface. A replacement observation well was installed as OW-23-13b with the screen interval at a depth of

5 to 10 feet below ground surface. SPT borings for the Sack Dam area were completed between

July 6 and August 21, 2023. UD borings were completed between July 10 and August 22, 2023, observation wells were installed between July 11 and August 23, 2023, and observation wells were developed between July 12 and August 25, 2023. Logs of the SPT and UD borings, along with well construction and development records can be found in Appendix A.

The Sack Dam study area exploration locations are shown on the Exploration Location Map

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20233893.001A/STO24R163917_R3 Page 18 of 37 February 7, 2024

3.1.3.1 Drilling Method

The SPT and UD borings and observation wells were drilled by Geo-Ex using a Diedrich D-70

Turbo track-mounted drill rig. The SPT and UD borings were drilled using solid stem auger and mud rotary methods. In general, the solid stem auger method was used until switching over to mud rotary methods around 5 feet below the ground surface. Observation wells were installed using hollow stem auger methods. Drilling was performed as outlined in the provided SOW.

The solid stem auger method used augers wrapped with spiral flights resulting in a 6-inch outer diameter (OD), and a cutting head on the lead auger. The SPT and UD borings were advanced by rotating the auger into the ground. Additional segments of the augers, typically 5 feet long, were attached to advance the borings. When sampling, lead auger and any connecting augers making up the drill string were removed entirely, and the sampler was lowered down to the sampling depth.

The drilling method for SPT and UD borings switched to mud rotary methods around a depth of about 5 feet below the ground surface. The solid stem augers were removed and 6-inch diameter, 5-foot-long casing segments were placed to act as casing during the mud rotary drilling. The casing was placed to reduce the potential for hydraulic fracturing and to help maintain stable side walls. The casing was advanced incrementally during drilling until a good seal was achieved. The mud rotary method used a 4½-inch-diameter drill bit (drag or tricone) and drill rods (N-size). As the boring was advanced, drilling stopped at selected intervals where the sampler was inserted inside the casing to the bottom of the borehole and a sample was retrieved. As the bit was advanced, drilling fluid consisting of water mixed with bentonite powder was pumped through the drill rod string and out the drill bit. The drilling fluid carried cuttings to the surface and discharged the cuttings from a collar into a tub. The drill cuttings were removed from the drilling fluid by shovel and discharged into 55-gallon drums for disposal. The drilling fluid was re-circulated down the borehole and provided pressure to put a positive head on the bottom of the borehole and support the open side walls of the borehole below the casing.

The hollow stem auger method used for the observation wells consisted of a seamless tube that is wrapped with spiral flights (8-inch OD), a center plug, and a cutting head on the lead auger.

The well was advanced by rotating the auger into the ground with the center plug in place to reduce the potential for soil cuttings entering the center of the auger and remaining within the well. Additional segments of the augers, typically 5-foot long, were attached to advance the well to the desired depth.

20233893.001A/STO24R163917_R3 Page 19 of 37 February 7, 2024

3.1.3.2 Sampling and Classification

A Qualified Field Representative (QFR) employed by Kleinfelder logged the SPT and UD borings in the field by visually identifying and classifying soils in general accordance with ASTM

International, Inc. (ASTM) D2488.

For the SPT borings, soil samples were typically collected at 2.5-foot depth intervals starting from about one foot below the ground surface and extending to the termination depths in accordance with the SOW.

Disturbed soil samples were obtained from the SPT borings using a Standard Penetration Test

(SPT) split spoon sampler (2-inch OD and 1 -inch inner diameter (ID)) with no liners in general accordance with ASTM D1586. The SPT sampler did not have space for liners and liners were not used.

The SPT samplers were driven 18 inches (unless refusal was encountered) into undisturbed soil using a calibrated automatic hammer having the equivalent energy of a 140-lb. hammer falling 30 inches. Refusal was defined as 50 blows for any penetration distance up to six inches. Blow counts were recorded at 6-inch depth intervals for each sample attempt and are reported on the boring logs in terms of uncorrected blows per six inches of penetration. Refusal blow counts are noted on the boring logs as 50 blows per the fraction of penetration in inches. The field measured blow count (Nf) is defined as the addition of the last two 6-inch blow count drives added together

(or the blow count required to drive the sampler the last 12 inches). Blow counts were also recorded at 0.1-foot depth intervals for the length of the driven sample Uncorrected blow counts recorded at 6-inch intervals are reported on the SPT logs presented in Appendix A. Blow counts recorded at 0.1-foot intervals are not presented on the SPT borings logs, but are presented in tabulated form in Appendix A. Densities of coarse grained soils were approximated using uncorrected SPT field blow counts (Nf) and consistencies of fine grained soils were approximated using field pocket penetrometer test values, as indicated on the Soil Description Key presented on Figure A-2 in Appendix A.

The SPT samples were collected in sealable plastic bags and bagged again in another sealable plastic bag to reduce loss of field moisture.

Intact soil samples were obtained from the UD borings using open-end-type thin wall Shelby tube samplers (5-inch outer diameter and typically 30-inches long) to target fine-grained soils at

20233893.001A/STO24R163917_R3 Page 20 of 37 February 7, 2024 intervals provided by BOR. The Shelby tube samplers were capped with plastic caps and sealed with tape to retain the field moisture. Shelby tubes were maintained in an upright position and secured during transport to minimize disturbance. Expansion packers were used when Shelby tubes were not entirely full of material to ensure that material was not allowed to move within the tube.

Stockton, California for further review and assignment of laboratory testing. Selected SPT and Shelby Tube samples remained in Stockton, California for dispersion, specific gravity, and other associated index tests. Selected Shelby Tube samples were transported to laboratories in Sacramento, California, and Dallas, Texas, or Cooper Testing Laboratory in Palo Alto, California for consolidation testing.

Upon completion of laboratory testing, field soil classifications were reviewed and updated based on available laboratory data as appropriate, in general accordance with ASTM D2487. The boring logs prepared for this study are presented in Appendix A.

3.1.3.3 Hammer Energy Report

Abe Construction Services, Inc. performed hammer energy measurement tests on the drive hammer used for the Sack Dam study area borings in general accordance with ASTM D4633.

The measured average hammer energy ratio for the Diedrich D-70 Turbo track-mounted drill rig was 92 percent. The hammer energy measurement report is presented in Appendix B.

3.1.3.4 CPT Soundings

CPT is an in-situ test that consists of pushing a cone penetrometer into the ground at a standard rate while recording data at regular intervals during penetration. Geo-Ex used an 18-ton rig to advance a 1.4-inch-diameter cone penetrometer vertically into the ground. The tip of the cone penetrometer has a conical tip and is the same diameter as the steel rod. The cone tip area is approximately 2.4 square inches, and the sleeve surface area is approximately 34.9 square inches. The cone penetrometer has sensors on the side sleeve which measure sleeve friction and on the conical tip which measure tip resistance. The cone penetrometer also includes a porous stone to measure pore pressures which can be used to estimate groundwater elevations. The sleeve friction and tip resistance measurements are collected at approximately 2-inch intervals.

The CPT plots present the cone tip resistance, sleeve friction, and pore pressure measured during advancement of the CPT and the soil behavior type which are derived from the data collected

20233893.001A/STO24R163917_R3 Page 21 of 37 February 7, 2024 during advancement of the CPT. CPT data can be correlated to equivalent USCS soil classifications. CPT correlations were used within the geologic interpretation discussions within this report.

At least one pore pressure dissipation test (PPDT) was conducted in each of the CPTs, with as many as up to five PPDTs performed within a single sounding. The PPDTs were performed below the water table to determine approximate water levels and provide estimates of hydraulic conductivity.