Mountain House Water Reclamation Facility Expansion

Mountain House, CA

PACE, as the Engineer of Record, provided design, permitting, construction, and startup services for the Phase III expansion of the Mountain House Water Reclamation Facility. The Phase III expansion brings the facility to a build-out capacity of 5.4 million gallons per day (MGD). The secondary treatment process was converted from a sequencing batch reactor (SBR) to a membrane bioreactor (MBR) to meet the existing waste discharge requirements and comply with California Title 22 recycled water requirements for unrestricted reuse. As part of the conversion, PACE designed the facility around the use of existing infrastructure. This included repurposing and subdividing the existing SBR process tanks into anoxic, oxic, and post-anoxic tanks prior to feeding the new MBR facility. The design also incorporated the expansion of the existing ultraviolet (UV) channel system for tertiary treatment with the modified and expanded facility. Previously, PACE was the Engineer of Record of the Phase II expansion, which replaced the 0.45 MGD aerated lagoon wastewater treatment plant with a 3.0 MGD advanced SBR water reclamation facility.

Key Features:

• Phase II 0.45 MGD aeration lagoon to 3.0 MGD advanced SBR conversion with construction of a two-tank hybrid SBR process for biological oxidation of organics and secondary clarification
• Phase III SBR to MBR conversion from 3 MGD to 5.4 MGD
• Large-scale six-train MBR system with wet weather peaking
• Permitted for unrestricted reuse and effluent discharge
• Energy-efficient aeration and low-energy mixers
• Underground treatment tanks minimize land use and aesthetic impacts
• Operational during construction – development of sequence of construction
• Performance specifications developed for major process equipment