Florence Lake Dam Fish Water Release

The Project comprised the installation, testing, and commissioning of the Florence Lake Dam Fish Water Release 36-inch Low Level Outlet Valve (LLOV) Upgrade.  Primary tasks include work area dewatering, discharge pipe modifications, waste management, excavation and backfilling, installation of new knife gate valves, piping, and underwater work to permanently open two existing sluice gates.

The scope included the following items of work:

Site Setup

• Setup Best Management Practices (BMPs)
• Setup cofferdam and pump downstream and dewater work area

Phase 1 East Outlet Work

• Continue 27 cubic feet per second (cfs) bypass through West Outlet
• Place new 36-inch diameter spool,Depend-O-Lok coupling, and valve on East Outlet
• Place new concrete anchor block
• Place operating platform and ladder at new 36-inch valve
• Paint and test new pipe
• Install 300 linear feet (lf) of 30-inch diameter corrugated metal discharge pipe (CMP)
• Perform East Inlet exploratory dive
• Partially remove East Intake screen to gain access for divers to East Inlet Gate
• Free-up/raise/weld-up or demolish East Gate, as required
• Replace East Intake screen to original condition
• Demolish East Gate shaft and operator
• Establish 27 cfs discharge through East Outlet by opening east downstream knife gate valve

Phase 2 West Outlet Work

• Partially remove West Inlet screen to gain access to West Inlet gate
• Weld West Gate into existing open position
• Remove existing 36-inch valve and 18-inch gate valve and replace with owner-furnished 36‑inch knife gate valve and 18-inch gate valve
• Remove and replace 8-inch diameter steel piping
• Paint new piping
• Demolish East Gate shaft and operator
• Remove West Inlet bulkhead
• Open west downstream knife gate valve and reestablish 27 cfs flow through West Outlet
• Remove temporary 30-inch diameter CMP

The contractor was required to manage and comply with specified water release turbidity requirements established by regulatory agency permit conditions.