Brief Project Description
The Augusta County Service authority (ACSA) owns and operates the Fishersville Regional STP which has an existing design flow of 2.0 million gallons per day (MGD). As a result of increasing flow and service demands, ACSA has identified possible expansion options and process performance enhancements. Based on forecasted growth rates within the service area ACSA has committed to the expansion of the facility to 4.0 MGD.
The Bay regulations for nutrient discharge control and waste load allocations for total nitrogen and total phosphorus adopted by the State Water Control Board have been incorporated into the design and expansion of the facility. To maintain capacity needs and meet waste load allocations, the facility design includes Enhanced Nutrient Removal technology to achieve discharge concentrations not to exceed 0.30 mg/l total phosphorus and 4.0 mg/l total nitrogen, along with annual loadings under the WQMP Regulation assigned to the Fishersville facility.
In summary, a 5-stage process configuration (i.e., Bardenpho) with polishing filters following the secondary clarifiers was selected for the 4.0 MGD Expansion and ENR Upgrade Project and will consist of the following:
- Installation of additional grit removal equipment in the existing aerated grit channel;
- Installation of a new mechanical bar screen;
- Installation of one new influent pump and modifications to the three existing pumps to provide additional peak flow capacity;
- Construction of pre-anoxic zone to mix return activated sludge with digester decant and belt filter press filtrate to remove excess nitrogen from the return flow;
- Modification of the two existing aeration basins to BNR basins;
- Construction of two new BNR basins;
- Installation of four new aeration blowers;
- Installation of secondary clarifier equipment in an existing tank to provide additional capacity;
- Construction of new tertiary filters (cloth disk filters);
- Installation of additional ultraviolet (U.V.) disinfection lamps in existing channels;
- Construction of methanol and alum storage and feed facilities;
- Construction of new belt filter press dewatering facilities; and
- Construction of two aerobic digesters including blowers.