Nutrient Reduction Program and Wastewater Treatment Plant Improvements
Greeley and Hansen, A TYLin Company, partnered with the City of Richmond Department of Public Utilities to develop the Nutrient Reduction Program for the Wastewater Treatment Plant to meet the required nitrogen and total phosphorus waste load allocations.
In collaboration with Greeley and Hansen, the City negotiated with Virginia DEQ to set favorable nutrient WLAs that are based on total nitrogen and total phosphorus concentrations of 8.0 mg/L and 0.5 mg/L, respectively. The Nutrient Reduction Program (NRP) consists of major upgrades of existing processes and construction of new facilities grouped into five major construction contracts. Overall the NRP maximized existing assets by upgrading existing facilities and dovetailed new and innovative processes into existing structures.
The upgrades and processes designed for Richmond were proposed to achieve higher levels of treatment without simply multiplying the existing treatment system. The NRP focused on balancing growth, resource management, and capital investments by maximizing the existing facilities, rehabilitating existing assets where feasible, and applying innovative processes to fit Richmond’s unique challenges. Greeley and Hansen also coordinated the NRP with the Richmond’s Phase III Combined Sewer Overflow (CSO) Controls. It was crucial to integrate the plant upgrades with the existing and new plant processes required to treat future increases in wet weather flows associated with the Richmond Combined Sewer System. The typical flow pattern at the Richmond WWTP is that the plant experiences a rapid increase in flow during a CSO event and a rapid decrease back to dry weather flow (DWF) conditions after CSO conditions cease to exist. The existing secondary treatment process was upgraded to meet nutrient reduction limits and to remain stable during these frequent and rapid increases and decreases in flow as the plant adjusts from DWF to CSO conditions and back to DWF conditions.
The approach to dive the NRP into five individual projects helped the City of Richmond meet their new permitted discharge requirements early on while managing their annual capital investment. By spreading the construction work out over several years, the construction bids were kept competitive.
Project Highlights:
- Favorable regulatory negotiation
- Integration of plant upgrades with existing and new plant processes required to treat future increases in wet weather flows
- Cost-effective sequencing to managing capital project investments and competitive bidding