Serene Lakes Sewer Pump Stations Rehabilitation

The Sierra Lakes County Water District (SLCWD) operates and maintains the sanitary sewer system and water system serving the community located approximately one mile south of Soda Springs, California (Figure 1). SLCWD is seeking California Clean Water State Revolving Fund (CA CWSRF) financing assistance for sewer pump station upgrades in their sanitary sewer system. SLCWD is proposing rehabilitation and upgrades to sewer pump stations (SPS) -02 and SPS-03, located in Placer County along Soda Springs Road, Dulzura Road, and Serene Road within Assessor’s Parcel Number 069-020-036-000 (Township 17 North, Range 14 East, Section 2 of Mount Diablo Meridian; Figure 2). Improvements include pump station infrastructure upgrades, installation of new valve vaults, wet well rehabilitation, pipeline replacement and abandonment, electrical enhancements, and surface restoration. All work will occur within existing roadways, pump station sites, and utility easements, with temporary disturbances limited to excavation areas, staging zones, and access routes. The proposed activities incorporate higher-efficiency pumps and motors, improved flow control, new force mains and optimized wet-well operation, which collectively reduce energy consumption and lifecycle operation and maintenance costs over the 30-year planning period. In addition, the upgraded stations offer safer access for maintenance, and advanced monitoring which improve system reliability and reduce the risk of service interruptions or sanitary sewer overflows. At SPS-02, a new 12-by-6-foot concrete valve vault will be installed, requiring excavation approximately 14 feet wide, 8 feet long, and 9 feet deep. The existing wet well will be rehabilitated with a 5-foot polymer concrete insert, a new access hatch, replacement of internal metals and pump components, and selective removal of portions of the existing structure, with an excavation of about 8 by 8 feet and 5 feet deep. Force main improvements include open-trench replacement of approximately 975 linear feet of 4-inch PVC C900 pipe and slip-lining of about 1,325 linear feet of 4-inch HDPE pipe into the existing 8-inch force main, requiring four temporary pits. A shallow discharge manhole will also be replaced. Approximately 500 linear feet of the existing 8-inch force main crossing a meadow will be abandoned, capped, and grout-filled, and all disturbed areas, including about 3,900 square feet of pavement, will be restored. Electrical upgrades include installation of approximately 40 linear feet of 1-inch PVC conduit between the new flow meter and the existing SPS-02 building. At SPS-03, a new 12-by-6-foot valve vault will be installed with a similar excavation footprint. The wet well will be rehabilitated using a 4.5-foot polymer concrete insert, new access hatch, replacement of piping and guide rails, pump replacement, and selective removal of the existing structure, requiring excavation of roughly 8 by 8 feet and 5 feet deep. Force main improvements include open-trench installation of approximately 565 linear feet of 4-inch PVC C900 pipe and replacement of a 5-foot-deep discharge manhole. A 50-foot drainage crossing will be rehabilitated by CIPP lining or slip-lining, with small excavations at each end. Approximately 450 linear feet of existing 6-inch force main will be abandoned, capped, or removed as needed, and disturbed pavement, estimated at 2,250 square feet, will be restored. Electrical improvements include installation of 25 linear feet of 1-inch PVC conduit between the new flow meter and an existing pull box. Construction activities will include excavation, trenching, underground infrastructure installation, equipment staging, and access for workers and machinery. All disturbed areas will be restored, and work will be confined to previously developed or disturbed corridors to minimize impacts on natural, biological, and cultural resources.