TO: Board of Supervisors
FROM: Christopher Silke, District Engineer
REPORT BY: Annamaria Martinez, Assistant Engineer
SUBJECT: Award New Construction Contract and Approve Amendment No. 2 to Agreement No. 240306B to include Construction Administration and Inspection Service for the LBRID Wastewater Ponds Groundwater Inflow Mitigation Project, LB 18-01
RECOMMENDATION
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Award a Construction Contract to Benchmark Civil Construction of Napa, CA for Phase I of the Lake Berryessa Resort Improvement District Wastewater Ponds Groundwater Inflow Mitigation Project, LB 18-01; and approve Amendment No. 2 to Agreement No. 240306B with GHD, Inc. adding construction administration and inspection services for the project. (Fiscal Impact: $550,499 Expense; Lake Berryessa Resort Improvement District Fund; Budgeted; Discretionary)
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BACKGROUND
Persistent heavy rainfall, runoff, and saturated soil conditions in the winter of 2017 filled Lake Berryessa Resort Improvement District (LBRID) wastewater ponds. Stored treated wastewater in Pond 7 had to be removed through the irrigation pump station and onto the land disposal fields to avoid damage to the earthen berm. Uncontrolled overland runoff ensued. The District's Waste Discharge Requirements (WDRs) permit prohibits land application runoff beyond tailwater capture ditches that return flow back to the ponds. Central Valley Regional Water Quality Control Board (Regional Board) subsequently served the District with a Notice of Violation in April 2017. To address the violation, Regional Board ordered the District to complete a Revised Water Balance Evaluation and submit a Work Plan if it is found that there is insufficient storage and/or disposal capacity. The District authorized Agreement No. 170871B with GHD, Inc. in May 2017 to provide engineering study services. The scope of the investigation centered on Water Balance Update and Calibration Model tasks executed in conformance with the Regional Board guidelines. The review ...
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