HRSD, the regional wastewater treatment utility that serves 18 cities and counties in southeast Virginia, had been experiencing high-pressures in their Williamsburg area force main network during wet weather events. These high pressure events caused operational trouble and, on occasion, resulted in SSOs in the collection system. Since the Regional Wet Weather Management Plan (RWWMP) of HRSD’s Federal Consent Decree to address these SSO issues was still years from finalization, HRSD staff studied the problem to come up with options to mitigate the issue. One option studied was to completely revamp and upgrade a number of pump stations with new pumps, piping and the necessary control equipment to address increased flow and pressures. Another option considered was to install a pressure reducing station (PRS) along the sewer force main system to reduce system pressures and thus increase capacity. After many options were considered, the preferred and the most cost-effective solution that could address the situation was an interim PRS. After HRSD’s procurement staff found the necessary purchasing mechanism to move forward with the solution, the local Xylem branch offered their support and assistance with the design, action plan, purchase, and equipment coordination.
HRSD developed a plan to integrate a pressure-reducing station (PRS) at a strategic location along the force main. Given HRSD’s dedication to regulatory compliance and environmental stewardship, and the need to align with long-term planned upgrades in their network, the new pressurereducing station was designed and implemented with the Godwin Dri-Prime Backup System (DBS). The Godwin DBS offered pumping equipment to provide additional capacity to handle wet weather flows and pressures and to minimize issues with sanitary sewer overflows (SSOs) during these events.
The short-term need was to get the PRS on-line as soon as possible, on Route 199 near Colonial Williamsburg. The HRSD design engineer provided design specifications to the Xylem team, and Xylem recommended two Godwin diesel-driven, critically silenced CD500M pumps with Final Tier 4 low-emission engines. The fuel supply was provided by two Godwin 250 gallon diesel fuel cubes with double-wall containment to ensure environmental safety.