Brief Project Description
The Waynesboro Sewage Treatment Plant (STP) uses trickling filters and rotating biological contactors to achieve secondary treatment of its wastewater. The plant was not designed for nitrogen or phosphorus removal. The existing process consists of mechanical screening, primary clarification, trickling filters, secondary clarification, rotating biological contactors, followed by chlorination, traveling bridge sand filters, dechlorination, and re-aeration prior to discharge to the South River. The waste solids are an-aerobically digested using a two stage process. The digested solids can be dewatered using a belt filter press, but are normally land applied in liquid form.
Under the proposal submitted for nutrient removal cost share, the existing WWTP will be upgraded to achieve state of the art (SOA) nutrient removal, and the plant capacity will be expanded from 4.0 MGD to 6.0 MGD. The proposed project will include the following:
- Construction of a new influent pump station consisting of two wet wells and four new submersible pumps, each with a 3,125 gallon per minute capacity (not grant eligible).
- Construction of a new preliminary treatment facility to accommodate the increased flows and to provide mechanical fine screening and grit removal. It will include two mechanical filter screens with 6 mm openings, one mechanical bar rack that will serve as a bypass, and two stirred vortex grit collectors (not grant eligible).
- Decommissioning of the existing trickling filters and rotating biological contactors.
- Construction of two new parallel 5-stage (anaerobic, anoxic, aerobic, anoxic, aerobic) treatment trains for biological nutrient removal (BNR).
- Installation of four new centrifugal blowers and new fine bubble membrane diffusers to provide the required air flow for the biological treatment.
- Construction of two 120 foot diameter final clarifiers and new return activated sludge (RAS) pump station.
- Construction of six deep bed denitrifying sand filters to provide additional nitrogen removal and particulate removal. Methanol will be used as a supplemental carbon source in the denitrifying filters.
- Installation of four new ultraviolet (UV) disinfection channels (not grant eligible).
- Construction of chemical storage and feed facilities for both alum and methanol. Alum will be added to the clarifier splitter box, the RAS pump discharge line, and upstream of the filters.
- Installation of two gravity belt filters. The belt filters will serve the dual purposes as both a gravity belt thickener to increase the waste activated sludge concentration prior to anaerobic digestion, and as a dewatering filter for the digested solids.
- Construction of a new administration building to house the laboratory, control room, operating and administrative functions
- Conversion of the old administration building into a maintenance shop (not grant eligible).
This grant has been prorated by 85% to account for the portion of the flow expansion considered to be reasonable and necessary by DEQ.