Water Treatment Plant Phase 1 and 2
Mountain House Community Services District

West Yost provided construction management and inspection services to Mountain House Community Services District (CSD) for Phase 1 and 2 of their water treatment plant construction and expansion. Phase 1 of the new water treatment plant, included two Trident filters with a 2.5 mgd treatment capacity, expandable to 20 mgd. Two miles of 36-inch diameter steel pipe were installed to transmit the water from the pump station to the treatment plant. The project included a 4 MG steel raw water tank that was constructed to hold an emergency supply of water and a 4.3 MG steel finished water tank that was constructed for storage capacity and fire protection. The new treatment plant used free chlorine as the disinfectant. A 5 mgd booster pump station was also constructed to deliver water to the community.

Phase 2, the plant upgrade project, consisted of pumping and process additions to the original treatment plant as an interim capacity project, followed by substantial replacement and expansion of the original plant with a larger plant having a reliable production capacity of 15 mgd. The interim capacity project consisted of additional pumping capacity, a third high-rate clarifier-filter package, an ultraviolet light disinfection system, and ammonia storage and feed facilities.

The new 15 mgd treatment plant included jet mixers, flocculators, inclined plate settlers, settled sludge collectors, granular media filters containing activated carbon, and an ultraviolet light disinfection system. Solids handling facilities for the pretreatment sludge and filter backwash wastewater included equalization basins and dewatering lagoons. Related improvements included additional pumps, standby power, and an integrated SCADA system.

Project featured the following: 

  • Raw Water Intake Structure, Pump Station, and Raw Water Pipeline
  • Water Storage Tank, Clearwell Tank and Pump System
  • Filter pumps and pre-engineered Trident Water Treatment Absorption Clarifier/Filters
  • Booster Pump Station
  • Administrative, Office and Laboratory Facilities
  • Filter Pump Station
  • Earthen Backwash Ponds
  • Reclaimed Water Pump Station, and Two Backwash Pump Stations
  • Miscellaneous Support Structures – Sludge Drying Bed, Stormwater & Overflow Retention Basin, and Sewage Lift Station and Pipeline To the Wastewater Treatment Plant