Title
Approve Change Order No. 12 to the contract with Graniterock Company for Nacimiento Dam spillway repair work to increase the contract amount by $400,000; and authorizing the General Manager to execute the Change Order.
(Staff: Mark Foxworthy)
Report
RECOMMENDATION:
It is recommended that the Monterey County Water Resources Board of Directors:
Approve Change Order No. 12 to the contract with Graniterock Company for Nacimiento Dam spillway repair work to increase the contract amount by $400,000; and authorize the General Manager to execute the Change Order.
SUMMARY/DISCUSSION:
Graniterock Company has performed repair work at Nacimiento Dam spillway in 2017, 2018, 2019, 2020, 2021 and 2023 in accordance with Federal Energy Regulatory Commission (FERC) and California Dept. of Water Resources, Division of Safety of Dams (DSOD) approved Scopes of Work consisting of delaminated concrete removal and replacement, concrete spall repair, sealing concrete slab joints, grinding concrete slab joint offsets, assisting with borescope exploration under concrete chute slabs, and concrete crack repair. The original contract with Graniterock Company to begin emergency spillway repairs was executed in 2017. Eleven change orders have been executed to continue repair work over multiple fiscal years, paying $1,074,034.27 for spillway repair work since 2017.
The spillway chute is designed to be fully supported by the rock foundation. Non-destructive testing to evaluate concrete contact with the rock foundation was performed in 2018, and locations indicating possible void spaces under the spillway chute concrete were found. The FERC approved Spillway Repair Scope of Work included boring small diameter holes through the spillway chute concrete to visually observe concrete/foundation contact conditions. In 2019, 45 boreholes were drilled, and conditions documented. An area 5 feet x 40 feet under spillway chute concrete Panel 14R was found to be suspended above the r...
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