Project Scope

The Jenny Lind Water System Tank A-B Transmission Pipeline Project is located in Rancho Calaveras near Valley Springs in western Calaveras County, CA.

The Project involves construction of a new, dedicated transmission main from the existing Tank A booster pump station to the existing Tank B. The Project is designed to remove the hydraulic bottleneck and improve conveyance to Tank B. The replacement transmission main is sized at 14-inch diameter for the first 13,600 linear feet from the Tank A pump station and 12-inch diameter for the last 6,500 linear feet before Tank B. The pipe material for the entire transmission main will be ductile iron.

From Tank A the transmission line follows Hartvickson Lane to its intersection with Baldwin Street, then along Baldwin Street, Usher Drive, and Wind River Road to the existing Tank B site. The new transmission pipeline will be in a separate open-cut trench parallel to the existing distribution system lines. The trench and new transmission pipeline will be located within the existing road ROW and established utility easements. All construction work will be conducted within the travel lanes or within the adjacent ROW (where feasible). Partial lane closure will take place during construction activities.

The new transmission pipeline will be isolated from the existing water distribution mains and only connected at five locations along its alignment with tie-in connections being made via Pressure Reducing Valve (PRV) stations at five locations along the pipeline. The transmission main will allow flow in both directions including forward pumping from Tank A to fill Tank B and, when the pump station is idle, gravity flow in the reverse direction allowing Tank B to supply water system demands when peak flow exceeds the pumping capacity.

While the new transmission pipeline is under construction, the existing distribution system will continue to operate in its current configuration and will continue to transfer water from Tank A pump station to fill Tank B. The existing distribution system will also continue to supply customer water demands along the existing route. However, upon completion of the new transmission pipeline, the existing distribution system will no longer be necessary for Tank A to B transmission and will be isolated and divided into smaller service zones. Each service zone will be supplied via dedicated PRV stations, Each pressure zone will be served by at least two PRV stations or each zone will be served by looping from multiple directions. A dead-end run, e.g. residential cul-de-sac, will be served by a single dedicated PRV station.

The existing Tank B inlet and outlet pipes are small and will be up-sized, replaced and reconfigured to comply with California waterworks standards. The new transmission main will discharge directly into Tank B, removing the inlet hydraulic constraint. The existing outlet will be retained with valve additions and modifications to allow for flow into the distribution system when the Tank A booster pump station is both operating and not operating (reverse gravity flow).