| Alleghany County - Lower Jackson River Regional WWTP
|| Blue Ridge Regional Office
Brief Project Description
Grantee: Alleghany County
Alleghany County has proposed to build and operate a new regional wastewater treatment plant (WWTP), which will take the existing 2 million gallon per day (MGD) Clifton Forge treatment plant offline. The proposed Lower Jackson River Regional WWTP will serve Alleghany County, the Town of Clifton Forge, and the Town of Iron Gate. Under new nutrient discharge control regulations for the Chesapeake Bay and its tributaries, the County received a combined, “bubbled” waste load allocation for nitrogen and phosphorus for its two treatment plants discharging within the James watershed. In addition to far reaching concerns for nutrient removal to meet tidal water quality standards, the Jackson River is the subject of a TMDL being developed by DEQ with the driver being lower total phosphorus concentrations for local water quality protection.
A Preliminary Engineering Report (PER) for a 3.5 MGD Lower Jackson River Regional WWTP was submitted to DEQ in February 2007, which evaluated three alternative biological processes for the new facility. Based on the capital and annual cost comparisons along with expected treatment performance, it was recommended that the proposed Lower Jackson River Regional WWTP, now sized with a design flow of 2.6 MGD, utilize the 5-stage Bardenpho activated sludge process.
Processes being installed, and their grant eligibility as Nutrient Reduction Technology (NRT), are described as follows:
A new Preliminary Treatment Facility (not grant eligible) will be constructed to provide raw wastewater influent screening, pumping, grit classifier/removal, and residuals handling. An odor control (biofilter) facility is also proposed.
Biological nutrient removal (partially grant eligible) via the Bardenpho process which includes parallel train, concrete aeration basins with fiberglass partitions and diffused aeration. A combined return activated sludge (RAS) and waste activated sludge (WAS) pump station is proposed.
Internal nitrified mixed liquor recycle (grant eligible) for denitrification will be provided.
Clarifiers (partially grant eligible): Two circular concrete tanks are proposed, each with an average design capacity of 1.3 MGD.
Effluent Polishing Filters (grant eligible): Two 10-disk cloth media filters in steel tanks mounted on a concrete pad; each filter is proposed for a peak capacity of 5 MGD.
UV Disinfection and Post-Aeration (not grant eligible).
Solids Handling and Dewatering (partially grant eligible): Two aerated sludge digesters and one centrifuge are proposed for the project.
Chemical Feed (grant eligible): Bulk chemical storage and feed facilities are proposed for alum to precipitate phosphorus and magnesium hydroxide for alkalinity control.
Electrical System Improvements (partially grant eligible): The plant will include a new onsite standby generator and switchgear building, in the event electrical service is disrupted.
Distributed Control System (partially grant eligible): A new plant-wide distributed control system will be provided to improve treatment plant automation and control.