Virginia Initiative Plant Nutrient Reduction Improvements
It is all in the approach
With sanitary sewer overflow (SSO) consent decree negotiations in progress, HRSD had to start planning for nutrient removal upgrades at its 40 million gallons per day Virginia Initiative Plant. We worked with HRSD to develop a plan that tackled multiple challenges head-on. Nutrient removal targets required effluent quality of 5 mg/l total nitrogen and 1 mg/l total phosphorus. Concurrently, uncertain plant hydraulic capacity requirements from developing SSO reduction goals had to be addressed. Together we performed analyses to compare the tradeoffs between each level of increased plant hydraulic capacity and develop a cost-effective approach. Other challenges included a tight site located over a closed municipal landfill and an aggressive completion schedule.
A phased delivery approach over the project lifecycle met the regulatory requirements and fast-tracked the construction schedule. Building information modeling (BIM) and interactive workshops facilitated informed decision-making, and an innovative design concept was developed. The design includes a new preliminary treatment facility with an influent pump station that is capable of discharging a portion of the peak flow to a new equalization tank and a new Versatile Bioreactor (VBR). With flexibility built into the design, these new facilities can operate in series or in parallel with the existing 3-stage nutrient removal processes, dependent on the priority of nutrient removal or hydraulic constraints.