ATTACHMENT 04 Geotechnical Data Report.pdf

Success Dam (On October 1, 2019 Success Dam was renamed to Schafer Dam within this report all references made to Success Dam refers to Schafer Dam.)

Tulare County, California

Tule River Spillway Enlargement Project Phase I

Geotechnical Data Report

Prepared for:

U.S. Army Corps of Engineers

Sacramento District

Prepared by:

17885 Von Karman, Suite 500 Irvine, California 92614

December 20, 2019

Success Dam Spillway Enlargement Project Geotechnical Data Report i

TABLE OF CONTENTS

1. INTRODUCTION

1.1 Project Overview

1.2 Disclaimer

1.3 Limitations

2. DESCRIPTION OF SITE AND PROPOSED CONSTRUCTION

2.1 Site Description

2.2 Proposed Construction

3. SUBSURFACE EXPLORATION PROGRAMS

3.1 Historic Subsurface Explorations and Studies

3.2 Geophysical Explorations

3.3 2019 Subsurface Exploration

3.4 Televiewer Surveys

4. LABORATORY TESTING

5. GEOLOGY AND SUBSURFACE CONDITIONS

5.1 Site Geology

5.2 Groundwater

LIST OF TABLES

No. Title Page

Table 1 – Success Dam Spillway – 2019 Boring Summary

Table 2 – Success Dam Spillway – Cerchar Test Results

LIST OF FIGURES

No. Title Page

Figure 4.1 – Direct shear test results (ϕ at in situ normal stress, ϕ at double the first)

Figure 4.2 – Unconfined compression strengths from 2003 and 2019 borings ii

APPENDICES

Appendix A – Project Plan View

Appendix B – Foundation Report Volumes 1 and 2, Original Project Design

Appendix C – Boring Locations and Logs of Borings, 2007 Exploration

Appendix D – Seismic Refraction Report

Appendix E – Boring Locations and Logs of Borings, 2019 Exploration

Appendix F – Rock Core Photographs, 2019 Exploration

Appendix G – Televiewer Reports

Appendix H – Cerchar Test Results

1. INTRODUCTION

1.1 Project Overview

Success Lake and Dam is a multi-purpose facility built on the Tule River. The dam was designed and built by the Corps of Engineers for flood control and storage of irrigation water. Construction of the zoned earth-filled dam and rock cut auxiliary spillway were completed in 1961. It spans 3,490 feet across the Tule River and is approximately 156 feet high. When at gross pool elevation

655.11 feet NAVD88 (652.5 feet NGVD29), the lake holds 82,300-acre feet of water with a surface area of 2,450 acres. The maximum length of the lake at this elevation is 3.5 miles with approximately 30 miles of shoreline.

Success Dam is located about 5 miles east and upstream of the City of Porterville, Tulare County, California. The Tule River drains about 390 square miles of the western slope of the Sierra Nevada mountain range into the reservoir created by the dam. The dam is capable of controlling releases within the downstream channel capacity, which is commonly referred to as a 0.0217 annual chance of an event (ACE) (i.e., a 46-year flood event). Events that are greater than the 46-year flood event would be routed (at least partially) through the auxiliary spillway via uncontrolled releases. The dam provides flood damage reduction benefits to the City of Porterville (pop: 52,000) and two other communities downstream of the dam. In addition, the dam helps protect several hundred thousand acres of valuable farmland west of the dam including the Tulare Lakebed from damaging winter and spring floods. Success Lake stores irrigation water late into the dry summer months in those years when there is sufficient water from the spring snowmelt to fill or partially fill the reservoir. A small privately-owned power plant was placed online in February 1990.

1.2 Disclaimer

Geotechnical Data Report (GDR) — This data report contains actual subsurface and other information that was collected at or adjacent to the Site by the Government, or for the Government, for use in preparing the Contract Documents. The Technical Data contained in this report upon whose accuracy the Contractor may rely are logs of borings, geophysical information, contractor-reported lab results, contractor-produced SPT hammer results, original construction photos, rock core photos, original construction-era documents, recorded measurements of subsurface water levels, and contractor-reported optical televiewer data. The GDR does not include any interpretation of the data. If opinions, or interpretive or speculative non-factual comments or statements appear in the GDR, such opinions, comments, or statements are not operative parts of the GDR and do not have contractual standing. Subject to that exception, the GDR is a Contract Document.

The Contractor may rely upon the general accuracy of the Technical Data contained in the GDR.

Except for such reliance on this Technical Data, the Contractor may not rely upon or make any Claim against the Government with respect to:

a. the completeness of this report for the Contractor’s purposes, including but not limited to, any aspects of the means, methods, techniques, sequences, and procedures of construction to be employed by the Contractor, and safety precautions and programs incident thereto, or

b. interpretations, opinions, and information contained in this report, or

c. any Contractor interpretation of or conclusion drawn from any Technical Data or any such other data, interpretations, opinions, or information.

1.3 Limitations

The Government does not represent that the boring logs, field and laboratory test results and other available geologic information show the conditions that will be encountered in performing the Work. The Government represents only that such information shows conditions at the locations of the borings, or other field data collection locations at the time that the data were collected. Each bidder must form their own opinion of the character of the work and of the materials to be excavated, make their own interpretations, and satisfy themselves by their own interpretations and research regarding all conditions affecting the Work to be performed. The Contractor must assume all responsibility for deductions and conclusions as to the nature or condition of all earth, rock and other materials to be excavated and the difficulties of making and maintaining the required excavations, and of performing other Work affected by the geology and subsurface conditions at the Site.

The Contractor must assume that any kind of rock and soil may be encountered in excavations, including mud, quicksand, very hard rock, or other materials that are difficult to handle.

2. DESCRIPTION OF SITE AND PROPOSED CONSTRUCTION

2.1 Site Description

The work consists of modifying the existing spillway along with additional grading downstream of the spillway and a new roadway alignment upstream of the spillway. A plan showing the project and the spillway on the right abutment of the dam is presented in Appendix A.

2.2 Proposed Construction

In 1999, a Feasibility Report was completed by the Corps of Engineers to support raising the spillway to increase the pool elevation and capacity of the lake.

The Tule River Spillway Enlargement Project consists of two separate construction phases. Phase 1 will consist of widening the spillway right abutment and realigning the access road. Phase 2 will consist of the remaining spillway widening, the construction of an ogee weir including the apron and abutments side walls, and erosion control for Highway 190 and Frazier Dike in addition to a recreation facility relocation and utility relocation.

The primary project improvements include blasting a wider spillway and constructing a new concrete ogee weir across the spillway approximately 167 feet upstream of the existing concrete sill, which will raise the gross pool elevation from 655.11 to 665.11 feet NAVD88, (652.5 to 662.5 NGVD29). Reservoir storage capacity will increase from 82,300 to 112,928 acre-feet (30,628 acre-feet increase), and reservoir surface area from 2,450 acres to 3,120 acres.

The proposed ogee weir will be a reinforced concrete structure approximately 350 feet wide across the spillway with a 20-foot-long horizontal section keyed into bedrock at each abutment. A 100-ft wide apron is to be placed immediately downstream of the ogee for erosion control. A 3-foot wide headcut wall at the upstream end of the ogee and a 3-foot wide cutoff wall at the downstream end of the apron are to be embedded 20 feet deep into the foundation.

An existing paved access road, which is along the northern side of the spillway (right abutment), will be realigned to accommodate the proposed ogee weir structure and will be partially relocated as a bench road in the spillway right abutment widening cut.

3. SUBSURFACE EXPLORATION PROGRAMS

The original foundation report for the project was completed in 1961 and included in Appendix B.

Since then, several historic subsurface explorations or studies have been performed in the spillway for various projects. In 2018 and 2019, geophysical explorations were performed on the existing rock cut on the right side of the spillway. In 2019, borings were drilled in the area of the project and downhole televiewer data was developed. Representative rock samples from the 2019 borings were tested for strength and other properties All of these explorations are discussed in more detail in the following sections.

3.1 Previous Subsurface Explorations

Borings were drilled in the spillway area in 1988, 2001, 2003, and 2007. The locations of pertinent borings from the 2007 exploration are shown on the boring location plan in Appendix C. Logs of the pertinent 2007 borings are also presented in Appendix C.

3.2 Geophysical Explorations

Seismic refraction testing was performed in the spillway and abutments in December 2018 to aid in determining bedrock quality for structure placement and excavatability. In the summer of 2019, two additional seismic lines were evaluated on the hillside above the largest cut. A report of the seismic refraction exploration is presented in Appendix D.

3.3 2019 Subsurface Exploration

For this project, 30 borings were drilled across the site in 2019. The locations of these 2019 borings are shown on a boring location plan in Appendix E and a table summarizing the 2019 boring information is shown on the following page. Logs of the 2019 borings are also presented in Appendix E.

During the drilling operations, photos were taken of the rock cores obtained in each 2019 boring.

These rock core photographs are presented in Appendix F. Please note that a photograph of Box 3 from boring 1F-19-25 is not provided. However, the contents of Box 3 consist of Core Runs 7, 8, and 9. Photos of Core Runs 7, 8, and 9 are provided in the appendix.

Table 1 – Success Dam Spillway – 2019 Boring Summary

BORING

DESIGNATION

DATE

DRILLING

COMPLETE

LOCATION (1)

(FEET) ELEVATION (1)

(FEET) EASTING NORTHING

1F-19-01 03/01/2019 6,583,841 1,906,305 723

1F-19-02 09/19/2019 6,583,625 1,906,187.5 794

1F-19-03 08/25/2019 6,583,539.9 1,906,188.7 780

1F-19-04 03/22/2019 6,583,525 1,906,897 765

1F-19-05 03/27/2019 6,583,238 1,906,732 795

1F-19-06 04/01/2019 6,583,069 1,906,577 750

1F-19-07 02/09/2019 6,583,756 1,906,430 655

1F-19-07A 02/19/2019 6,583,745.7 1,906,422.9 655

1F-19-08 02/26/2019 6,583,767 1,906,573 653

1F-19-09 02/20/2019 6,583,648 1,906,419 653

1F-19-10 02/27/2019 6,583,692 1,906,509 653

1F-19-11 02/25/2019 6,583,608 1,906,607 655

1F-19-12 02/28/2019 6,583,550 1,906,409 653

1F-19-13 02/06/2019 6,583,510.1 1,906,519.7 653

1F-19-14 02/08/2019 6,583,279 1,906,385 653

1F-19-15 02/23/2019 6,583,550 1,906,593 652

1F-19-16 02/16/2019 6,583,169 1,905,836 648

1F-19-17 08/07/2019 6,584,076.5 1,906,842.3 692

1F-19-18 08/06/2019 6,584,446.8 1,906,981.7 681

1F-19-19 08/09/2019 6,583,017.1 1,906,013.6 693

1F-19-20 02/14/2019 6,584,630 1,907,377 665

1F-19-21 02/15/2019 6,584,608 1,907,706 677

1F-19-22 04/02/2019 6,583,049 1,906,252 690

1F-19-23 02/21/2019 6,583,193.4 1,906,108.4 651

1F-19-24 08/10/2019 6,583,165.9 1,905,868.8 649

1F-19-25 08/13/2019 6,583,143.8 1,905,999.2 650

1F-19-26 10/04/2019 6,583,637.7 1,906,133.8 796

1F-19-27 09/22/2019 6,583,645.3 1,906,037.0 784

1F-19-28 08/08/2019 6,584,049.9 1,906,988.4 747.6

1F-19-29 10/05/2019 6,583,747.1 1,906,259.5 750

(1) Coordinates and elevations provided by USACE, NAD 83, CA State Plane Zone 4, Vertical datum

NAVD88

3.4 Televiewer Surveys

Two televiewer surveys were performed as part of the 2019 subsurface explorations. The first survey, completed in May 2019, was performed on borings 1F-19-4 through -6, 1F-19-8 through -10, 1F-19-12, 1F-19-15, and 1F-19-22. The second survey was completed in November 2019 and was performed on borings 1F-19-19 and 1F-19-24 through -29. Reports for both televiewer surveys are presented in Appendix G.

4. LABORATORY TESTING

The laboratory testing program consisted of unconfined compression tests, direct shear tests, and Cerchar abrasion testing. The results of the Cerchar testing are summarized below and the individual Cerchar abrasion test results are presented in Appendix H.

Table 2 – Success Dam Spillway – Cerchar Test Results Abrasive Index - ASTM D7625 - 1 test per sample

Borehole # Depth ft Rock Type Weathering

Results Corrected

CAI

1F-19-04 65.2 Quartzite - Very Hard Slightly 4.49

1F-19-06 60.8 Quartzite - Hard Slightly 4.50

1F-19-22 34.5 Granodiorite - Hard Slightly 3.96

1F-19-05 92.0 Granodiorite - Mod. Hard Moderately to Slightly 2.87

1F-19-06 33.1 Granodiorite - Mod. Hard Moderately 2.21

1F-19-05 13.0 Granodiorite - Mod. Soft Moderately to Highly 1.69

Tests completed 14 June 2019 CAI - CERCHAR Abrasive Index Corrected CAI - corrected for saw cut samples

The results of the direct shear testing are shown on Figure 4.1 below. The results of the unconfined strength testing from the 2003 and 2019 explorations are shown on Figure 4.2.

Figure 4.1 – Direct shear test results (ϕ at in situ normal stress, ϕ at double the first).

CAI – Cerchar Abrasion Index

Figure 4.2 – Unconfined compression strengths from 2003 and 2019 borings.

5. GEOLOGY AND SUBSURFACE CONDITIONS

5.1 Site Geology

The geology on the right abutment of the dam is characterized by granitic and metamorphic bedrock locally underlying alluvium and colluvium. Metamorphic rocks, predominantly quartzite and meta-volcanic rocks, comprise a large portion of the top of the right abutment hill. These rocks represent the older rock that was intruded by younger granitic rocks. The granitic rocks range from diorite to granodiorite and are exposed in the cut slopes and much of the floor of the spillway.

Brief descriptions of the rock and soil on the right abutment of the dam are presented below in order from youngest to oldest.

Colluvium: Colluvium observed near the right abutment of the dam is generally dark brown-to-brown clay and gravelly clay, that typically contains subangular to angular rock fragments. The clay ranges from low to medium plasticity. Lower flanks of hillslopes often include accumulations of stiff clayey colluvium with shrink-swell polishing that may be more than 5 feet thick. The age of the colluvium is estimated to be Holocene/Recent (≤ 11,000 years old).

Alluvium: Undifferentiated: Alluvium underlies terraces on both sides of the spillway channel and is exposed at several locations along the channel. It is believed this alluvium originated within the local natural drainages on the west side of the spillway excavation. The alluvium generally consists of loose to dense sandy and silty gravel with cobbles that range from 3-inches to about 8-inches.

Most of alluvium is likely Holocene (less than 11,000 years old). However, certain exposures may be as old as late Pleistocene (11,000 to 1 million years old).

Alluvial Terrace Deposit: The lower flanks of the dam's right abutment hill are underlain by alluvial terrace and channel deposits consisting of alluvium carried downstream by the Tule River or a tributary. Subsequent stream incision abandoned the terrace which protected the deposits from erosion or burial. Consequently, these deposits weathered in place. These deposits consist of yellowish red sandy and clayey gravels, are well consolidated, dense to very dense, locally cemented with carbonate, and highly weathered. The upper sections of terrace deposits (i.e., near the existing ground surface, especially near the back edges of the terraces) are often finer grained, lacking much of the gravel and cobbles that generally comprise the Alluvial Terrace Deposits.

These finer grained sections are composed of reddish brown to yellowish red clay, gravelly clay, and sandy clay. The age of the alluvial terrace deposit is estimated to be Pleistocene (11,000 to 2 million years old).

Pegmatites, Aplites, and Quartz Veins: Dikes of both pegmatite and aplite are found cutting the various metamorphic and igneous rocks at the right abutment hill of the dam and in the spillway.

Quartz veins were also observed filling fractures in bedrock. In general, these units are less weathered than the surrounding rock, and protrude slightly from the outcrops/cuts. Where observed, pegmatite dikes range from about 2 to 10 inches thick. The few aplite dikes observed range from <1 to about 2 inches thick. Quartz veins are commonly discontinuous and range from <1 to a few inches thick. The age of the pegmatites, aplites, and quartz veins is estimated to be Cretaceous - Jurassic (67 to 208 million years old).

Granites (diorite to granodiorite): Rock exposed in most of the spillway consists of granitic lithologies commonly referred to as granite. These rocks include diorite, quartz diorite and granodiorite that grade into each other with no clear-cut intrusive contact. The granites are generally light to medium gray and fine to coarse grained. The granites show more differential weathering than the other igneous rocks present at the dam site. Fresh exposures are hard and strong to very strong. However, near the natural ground surface, the granites are commonly weathered and moderately soft and weak. Where completely weathered, the granites are a brownish tan sandy soil. The age of the granite is estimated to be Cretaceous - Jurassic (67 to 208 million years old).

Gabbro: A body of gabbro is found near the top of the dam' right abutment hill. The gabbro is fine grained with few coarse crystals, generally medium to dark gray, slightly fractured, hard to very hard, strong to extremely strong, and slightly weathered.

Meta-basalts and Related Rock Types: There are isolated outcrops and small bodies of metavolcanic rock (most commonly meta-basalt) at various locations along the eastern flank of the right abutment of the dam. These rocks are sometimes included within igneous intrusions and as dikes and sills associated with the metasedimentary rocks. Much of the meta-basalt at the site can be considered amphibolite petrographically but is generally classified as meta-basalt at most locations. The meta-basalt is generally moderately hard to hard, greenish to dark gray and black with an aphanitic to medium grained texture. Weathering is variable. The age of the meta-basalts and related rock types is estimated to be Jurassic – Triassic (144 to 245 million years old).

Quartzite: The south side of the dam's right abutment hill is dominated by quartzite. Smaller bodies of quartzite are found elsewhere throughout the dam's right abutment hill and the spillway, either as xenoliths within granitic intrusions, or as country rock intruded by dikes and/or sills of variable lithology. The quartzite ranges from light green to brown, gray, olive, and black and generally is fine to medium grained. Where observed, fracturing in quartzite is generally highly variable, from very closely spaced to widely spaced. The quartzite ranges from hard to very hard, and moderately strong to extremely strong. Weathering is generally slight.

The quartzite at the dam site is derived from quartz-rich sandstone which includes various pelitic impurities. Quartz predominates and biotite is common. These impurities are aligned in wavy bands within the rock, presenting a moderately well-developed metamorphic foliation. The foliation (or banding), creates preferential zones of weakness and jointing within the quartzite. The age of the quartzite is estimated to be Pre-Cretaceous to Permian (144 to 320 million years old).

Quartz-Mica Schist: Small to medium-sized bodies of quartz-mica schist are found with quartzite in the spillway. The schist is generally soft to moderately hard, dark gray to gray, and generally fine grained with a schistose texture. The schist was derived from impure sandstones by a dynamothermal metamorphic process which includes high temperatures and pressures, similar to what is expected during mountain building phases. The schist is generally closely to very closely foliated, moderately to closely fractured and moderately to severely weathered. The age of the quartz-mica schist is estimated to be Pre-Cretaceous to Permian (144 to 320 million years old).

5.2 Groundwater

Groundwater observations during the drilling operations were noted on the boring logs. However, since water was used to core the rock, these observations may not be reliable nor reflective of the groundwater levels at the site.

APPENDIX A – PROJECT PLAN VIEW

APPENDIX B – FOUNDATION REPORT VOLUMES 1 AND 2, ORIGINAL

PROJECT DESIGN

APPENDIX C – BORING LOCATIONS AND LOGS OF BORINGS, 2007

EXPLORATION

APPENDIX D – SEISMIC REFRACTION REPORT

APPENDIX E – BORING LOCATIONS AND LOGS OF BORINGS, 2019

EXPLORATION

APPENDIX F – ROCK CORE PHOTOGRAPHS, 2019 EXPLORATION

APPENDIX G – TELEVIEWER REPORTS

APPENDIX H – CERCHAR TEST RESULTS