River Islands Water, Wastewater, and Recycled Water Master Plan

Lathrop, CA


River Islands, located within the Stewart Track in the City of Lathrop, is a 5,000-acre master-planned community located southwest of the San Joaquin River. PACE was hired to provide master planning and design services for the development’s potable water, recycled water, and sanitary sewer infrastructure. PACE worked with the developer’s general civil engineer to analyze and model all wet utility infrastructure and verify each system’s performance under average, maximum, and peak operating conditions. For the potable water distribution system model, peak conditions included verifying the performance of the system to meet fire flow requirements under maximum and peak hour potable water demands. PACE was also responsible for determining the design requirements for all infrastructure improvements, such as the pumping capacity of lift stations and booster pump stations and size and height requirements for storage tank sites.


The potable water distribution model was analyzed using WaterGEMS and includes approximately 325,000 linear feet of distribution piping, 20,000 gallons per minute of pumping capacity across two booster pump stations, and 10.8 million gallons of storage. The sanitary sewer model was created and analyzed within ArcGIS and includes approximately 390,000 linear feet of collection piping and six sewer lift stations. All model results were summarized in individual master plan reports submitted to and approved by the City of Lathrop.


Key Features:

  • Sanitary Sewer Model – Recommended the installation and provided the design requirements of recycled water flushing stations for the trunk lines as well as chemical dosing systems at the lift stations
  • Sanitary Sewer Model – Determined the velocity and corresponding Froude numbers of all the sewer lines within the development
  • Potable Water Distribution Model – Inputted isolation valves into the distribution model allowing for emergency conditions such as pipe maintenance to be simulated

River Islands at Lathrop

Wastewater Infrastructure, Water Infrastructure