Industry_Day_MS_Teams_PowerPoint_13JUN24_4.pdf

B.F. Sisk Safety of Dams Modifications

Industry Day Phase II Construction SVS, NVS, SW-165, Borrow Area Development

June 13 - 14, 2024

Presentation Outline

• Introduction - (Carlos Lopez)

• Location – (Henry Garcia)

• Background - (Henry Garcia)

• Site - (Henry Garcia)

• Geology – (Bryan Holmes)

• Purpose - (James Olsen)

• Modification Features / Components - (James Olsen)

• Schedule - (Henry Garcia)

Background

• San Luis Dam (now B.F. Sisk Dam)

• Constructed between 1963 and 1967

• Provides water for the Federal Project (CVP) and the California State Water Project (SWP)

• Provides power generation and recreational benefits

• Dam impounds San Luis Reservoir

• Provides over 2 million ac-ft of off-stream storage

• Hydraulic Height: 303 feet

• Structural Height: 382 feet

• Crest Length: 18,600 feet

• Embankment Volume: 78 million yd3

• Minimum Freeboard: 10 feet

The B.F. Sisk Dam dedication speech was given by President John F.

Kennedy during the groundbreaking ceremony for the San Luis Reservoir in California in 1962 while standing on Kennedy Hill

Existing Facility Components

• Dam (~3.5 miles long)

• Morning-glory spillway intake

• 90-foot vertical shaft

• 9.5-foot-diameter conduit through dam, founded on bedrock

• 1,000-foot-long open channel concrete chute leading to stilling basin

• Outlet Works

• Four (4) penstocks (17.5-foot-diameter) tunneled through bedrock leading from the intake towers to the Gianelli Pumping-Generating Plant

Dam

3.5 Miles Intake towers

Spillway intake

Phase II Feature Components

• South Valley Section (SVS) Construction of a zoned stability berm

• North Valley Section (NVS) Construction of a stability berm over the shear key

• Slopewash 165 (SW-165) Construction of a stability berm over the shear key

SVS

NVS

SW-165

State Route 152 haul road crossing

Phase II BA’s and Basalt Hill Quarry Locations

Phase 1 Status Update

• Completed 2023

• Spillway Extension

• Slopewash 36

• Slopewash 180

• Construction ongoing

• Slopewash 145

• Contract Completion January 2025

View looking SE at SW145 construction of berm and filter drains

Site Geology

• Dam constructed across 1-mile gap in the foothills

• Left/Right Abutments founded on

Panoche Formation marine sedimentary rocks

• Conglomerate

• Sandstone

• Shale (Interbedded Shale-Sandstone)

• Abutments veneered by clayey Slopewash soil

B.F. Sisk Dam - Geologic Map and Profiles (USBR, 1974)

• North Valley Section (NVS) founded on shallow alluvial deposits

• South Valley Section (SVS) founded on deeper (~160 ft.) fluvial and lacustrine deposits

• Upstream cutoff trench to bedrock, except in SVS

• SVS includes upstream and downstream foundation trenches, keyed into basal gravel

B.F. Sisk Dam - Geologic Map and Profiles (USBR, 1974)

• Basalt Hill Quarry

• Resistant cap of basaltic flows

• Source for all rockfill materials and 9C sand

• Borrow Area 6

• Predominantly clay to clayey sand with interbedded sand/gravel

• Source for Zone 1 and Zone 8

• Borrow Areas 12/14

• Panoche Interbedded Shale and

Sandstone

• Source for Zone 8

• Already in-use for Ph. I

• Borrow Areas 20/21

• Currently being investigated

• Anticipated to be similar to 12/14

B.F. Sisk Dam

Basalt Hill Quarry

Borrow Area 12/14

Borrow Area 6

Borrow Area 20/21

Left Abutment Section

Right Abutment section

Valley Section

NVS SVS

Slopewash Section with Existing Berm North Valley Section (NVS) South Valley Section (SVS)

SOD Modifications

• Embankment sections and nomenclature

• Based primarily on Geology

Why SOD Modifications?

• Seismic hazard at the site is very high

• High potential for liquefaction at the NVS section

• Fine-grained soils within the Slopewash and SVS sections indicate significant strength loss could occur during an earthquake.

• NVS, SVS and Slopewash section (SW-165) of the embankment could experience severe deformations and possibly fail due to reservoir overtopping caused by loss of freeboard or internal erosion during a large seismic event.

• The downstream floodplain contains a large population of people who would be subject to flooding from a dam failure.

Phase II Modifications

• Downstream shear keys and berms to stabilize the embankment at

“weak” foundation areas

• Excavation and placement of shear key material and stability berm and toe drains at SW-165

• Construction of a zoned stability berm over the South Valley Section (SVS) and

North Valley Section (NVS) with subsequent zoned backfill

• Development of existing Borrow Areas 6, 12, and 14

• Development of future Borrow Areas 20 and 21

• Future Work

• SOD Crest Raise and filter placement on the downstream face of the dam

• Inclusion of Dam Raise and Expansion Project Crest Raise and filter components

• Site Restoration, access roads, and install final instrumentation

NVS and SVS Berms – Plan View

• Why differentiated? Legacy of past design concepts and differing geology

• Depth to bedrock is shallower at NVS (30 to 40ft at toe of dam)

• Depth to Rock at SVS is great (up to ~200ft)

North Valley Section

• Main features: large stability berm and blanket drain (higher than SVS)

• Blanket drain material produced on site: Zone 11 (#57) and Zone 9C

South Valley Section

• Similar to NVS but…

• Lower, wider stability berm needed to limit deformation

• Transverse (‘finger’) drains every 200 feet

• Material produced on site at Basalt Hill (i.e., Zone 11 and 9C)

Zone 11 and 9C Materials

• Zone 9C produced during test production

• Similar to C33 sand

• Up to 10% fines

• Zone 11 (i.e., ASTM C33 No. 57 stone)

• Produced on site during current phase of construction

Test production of Zone 9C from Basalt Hill

Slopewash 165

2000 ft long

Minimal excavation below existing toe. Anticipated 1- to 2-month duration

60 gpm or less anticipated

• 2000 ft long

• Minimal excavation below existing toe

• Weak Slopewash interrupted by existing Zone 6

Slopewash 165

• Completed berm includes Zone 10 shear key material (15-inch minus, produced on site)

• Also includes Zone 11, 9C, and 9A

• 9A is imported filter sand (C33, 3% fines max)

• New Drains and extension of existing toe drains not shown

Approximate Material Requirements

State Route-152 Haul Road – Borrow Area 6 to and from Project Site

Proposed Haul Road

2024 2025 2026 2027 2028 2029 2030 2031 2032

Contract-2 Solicitation and Construction

Future Work

• Contract-2:

• SW-165

• NVS

• SVS

• BA’s

• Future Work

• 10-foot Crest Raise for the BF Sisk SOD Project.

• Additional 10-foot Crest Raise for BF Sisk Dam Raise and Expansion Project

Contracting Plans

Contracting Plans (cont.)

• Pre-solicitation: Summer 2024

• Solicitation: Fall 2024

• Award: Spring 2025

Phase II SOD Modifications

• Quarry production of granular materials at Basalt Hill

• Production of all granular embankment materials EXCEPT Zone 9A (commercially sourced C-33 fine aggregate)

• Zone 8 (Miscellaneous Material) can utilize minus 8-inch waste material from Basalt Hill

• Developing means to move material to the site from the Quarry and Borrow Area 6 (located across State Route-152).

• The scope of Contract-2 is to construct shear key/berm at Slopewash-165 and drainage features/berm at the NVS, SVS.

Borrow Areas 6, 12, and 14 will be developed to provide materials for use as part of this contract along with future development of Borrow Areas 20 and 21.

Construction & Schedule Challenges

• Material processing from Basalt Hill and development and distribution at Borrow Areas

• Quarry Mining and Restoration

• Haul Roads development/maintenance

• Environmental Compliance

• Labor Market

• Safety

BF Sisk Phase 2 Industry Day Site Visit Agenda

• Meet at Borrow Area 14 "Meeting Location" (Identified on Map) …………. 8:30 am

• Assign Tour Guides, Break into Groups, Review JHA ……………… 8:30 am - 9:00am

• Site Visit, SW165, NVS, SVS, Basalt Quarry, Borrow Areas ……… 9:00am - 12:00pm

• PPE - Please wear appropriate clothing for active construction site. Access Roads are rough/rocky and cars and or lower ground clearance vehicles are not recommended.

• Sign-in Sheet will be shared on sam.gov.

No questions will be addressed at either the site visit or virtual meeting. All questions shall be emailed to the Contracting Officer (Carlos Lopez at aclopez@usbr.gov) and Contract Specialist (Roxana Ahola at rahola@usbr.gov) for consideration.