BOARD AGENDA MEMORANDUM
Government Code ? 84308 Applies: Yes ? No ?
(If "YES" Complete Attachment A - Gov. Code ? 84308)
SUBJECT:
Title
Receive an Update on the Anderson Dam Tunnel Project.
End
RECOMMENDATION:
Recommendation
Receive an Update on the Anderson Dam Tunnel Project.
Body
SUMMARY:
Background
The Anderson Dam Tunnel Project (ADTP), Project No. 91864006, is currently being constructed and includes building a diversion system to augment the existing outlet, consisting of a new diversion tunnel, an outlet structure, a micro-tunnel lake tap, and modifications to Coyote Creek just downstream of the base of the dam. Once completed, the ADTP will serve as the Stage 1 Diversion System to divert inflows from the reservoir to Coyote Creek during the beginning of the Anderson Dam Seismic Retrofit Project (ADSRP). All of the ADTP elements, except for the micro-tunnel lake tap portion, will be incorporated into the final configuration of the ADSRP.
On April 27, 2021, Valley Water's Board of Directors awarded the construction contract for the ADTP to the top-ranked best-value proposer, Flatiron West, Inc. (Contractor), in the sum of $161,140,321 and approved a contingency amount of $40,000,000 (25% of the contract price).
On January 28, 2025, the Board of Directors approved an increase of $40,000,000 to the construction contract contingency sum, bringing the total construction contract contingency to $80,000,000.
Project Construction
Several major elements of the ADTP construction have been completed to date, including:
* Tunnel Excavation and Initial Lining
Tunnel excavation and initial lining of the tunnel were completed in April 2024. The Contractor used conventional mining methods, including drilling and blasting the rock to complete the excavation. The initial lining installed to support the excavation consists of an 8-inch thick layer of fiber-reinforced shotcrete (spray-applied concrete) and steel support arches spaced every 3 to 5 feet.
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