anderson dam seismic retrofit project
TRANSCRIPT
Anderson Dam SeismicRetrofit Project
Joint SCVWD/City of San Jose Meeting | April 28, 2017
Attachment 1Pg. 1 of 11
| Joint SCVWD/City of San Jose Meeting 4-28-2017
Project Overview
Anderson Dam Existing Configuration
Spillway Outlet Pipe Dam Embankment Crest of Dam
Attachment 1Pg. 2 of 11
| Joint SCVWD/City of San Jose Meeting 4-28-2017
Project Overview
Problem Definition
► Magnitude 7.2 Earthquake on the Calaveras Fault or M6.6 on the Coyote Creek Fault► Embankment slumps up to 25 feet due to
liquefaction of lower fine fill and alluvium► Outlet conduit buckles up to 4 feet due to fault
rupture on the Range Front Fault
► Changes in Regulatory Requirements (DSOD and FERC)► Outlet works does not meet current emergency
drawdown criteria► Spillway undersized for Probable Maximum Flood
Attachment 1Pg. 3 of 11
| Joint SCVWD/City of San Jose Meeting 4-28-2017
2013 Project: Liquefaction, New Intake and Outlets, Spillway / Crest Modifications
New sloping intake
10 feet high cofferdam (drained reservoir)
Spillway modifications New High Level Outlet conduit
Upstream embankment buttress
Downstream embankment buttress
New lower level conduitright abutment alignment
Abandon existing outlet pipe
Attachment 1Pg. 4 of 11
| Joint SCVWD/City of San Jose Meeting 4-28-2017
June 2016: Dam Failure by Fault Rupture
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Shown: Mapped traces of Coyote Creek Fault
Attachment 1Pg. 5 of 11
| Joint SCVWD/City of San Jose Meeting 4-28-2017
2016 Modified Project
Cross-Section: 2013 Recommended Project
Cross-Section: 2016 Modified Project
New Gravel FillNew Gravel
Fill
New Filter & Transition ZonesNew Transition Zone
Bedrock
“ ““ “
Core
Core Remnant
Attachment 1Pg. 6 of 11
| Joint SCVWD/City of San Jose Meeting 4-28-2017
2016 Modified Project Footprint
Existing dam clay core
Remnant dam clay core to remain
Post Project dam footprint
Existing dam footprint
Attachment 1Pg. 7 of 11
8 Joint SCVWD/City of San Jose Meeting 4-28-2017
Retrofit Includes High-Level and Low-Level Outlets
10% of Storage90% of Storage
Low-Level Outlet – 6-foot diameter
High-Level Outlet12-ft diameter
Spillway Invert
Max Water Surface EL 628 ftDam Crest
Anderson Dam Cross-Section
Attachment 1Pg. 8 of 11
| Joint SCVWD/City of San Jose Meeting 4-28-2017
2016 Modified Project Construction Sequence
Year 1:
Lower Dam to Interim Height
(El 570 ft)
Lower Dam to remnant core;
Dry Season*Year 2:
Dry Season Year 3:
Dry Season Year 4:
Winter Year 4:Reservoir begins
to re-fill
Full Height Over Winter
(El 647 ft)Interim EL
(570 ft)Winter 1
Interim EL (570 ft)
Winter 2
Complete Construction
(El 656 ft)
Build Dam to Full Elevation
(El 656 ft)
Dewatering, OutletTunnel Construction
* Dry Season = April to October
re-build to Interim Height
(El 570 ft)
Attachment 1Pg. 9 of 11
| Joint SCVWD/City of San Jose Meeting 4-28-2017
Project Schedule
2017 2018 20192013 2014 2015 2016
We are here
2020
Design
Construction
NEPA/CEQA/Permitting
Original Baseline
Legend
NEPA / CEQA / Permitting
Design
Construction through 2024
2021 2022
December, 2016
Attachment 1Pg. 10 of 11
Summary
► 2016 Modified Project
► More extensive embankment retrofit
► Increases total cost of Project from $200M to $400M
► Start of Construction extended to 2020
► Supported by dam regulators and Board of Consultants
Attachment 1Pg. 11 of 11