Brief Project Description
The existing New Kent County-Parham Landing wastewater treatment plant (WWTP) is a 0.568 MGD facility providing tertiary treatment with discharge to the Pamunkey River in the York River basin. As detailed in a September 2008 Preliminary Engineering Plan (PER) Amendment, the WWTP will be expanded to 2.0 MGD with installation of nutrient reduction technology (NRT) to achieve annual averages of 6.0 mg/L total nitrogen and 0.70 mg/L total phosphorus The County's Chickahominy WWTP (0.41 MGD design flow; James River basin discharge) will be taken offline and flows rerouted to the upgraded/expanded Parham Landing WWTP. Expansion to 2.0 MGD will accommodate the consolidated wastewater and also the projected flows for both service areas. In addition to providing centralized NRT at Parham Landing WWTP, the project includes provisions for reclaimed water to be supplied to the County's bulk irrigation users via a pump station and force main. When influent flow exceeds the reclaimed water demand, the facility will discharge to the Pamunkey River.
The original PER for the project, submitted in June 2006, called for a 3.0 MGD Parham Landing WWTP with NRT. Several biological treatment alternatives were evaluated, with a Sequencing Batch Reactor (SBR) system selected for NRT, along with tertiary filtration and chemical addition. Factors considered in this selection included reliability in meeting effluent limits, total present worth, accommodation of low flows during start-up, operator familiarity and adaptability to future conditions. Following submission of the original PER, the County became concerned about the lack of water for their bulk irrigation users and revised the expansion to just 2.0 MGD, saving funds that could be used for the reclaimed water system. The same treatment unit processes are planned for the 2.0 MGD plant, although many are now down-sized. Processes being installed, and their grant eligibility as NRT, are described as follows.
Primary Treatment (not grant eligible)
- Preliminary Fine Screens, Grit Removal, and Pre-Equalization.
- Biological Nutrient Removal (partially grant eligible) via the SBR process.
- Chemical Storage/Addition (not receiving cost-share) existing tankage for alum and magnesium hydroxide will be converted to carbon storage. Three additional tanks for alum storage will be installed in the existing sodium hypochlorite storage room of the existing chemical building. A new magnesium hydroxide tote will be made available in the new Administration/Storage/Chemical Building (converted existing Filter Building). New skid-mounted feed systems will be installed for all chemicals.
- Filtration (partially grant eligible) using two units, each containing ten disk filters.
- Final effluent UV Disinfection (not grant eligible) for surface discharge.
- A new Sodium Hypochlorite system (not grant eligible) will be installed in the existing non-potable water pump station structure to provide a chlorine residual in the reclaimed water sent back to the bulk users.
- Post Aeration and Metering (not grant eligible).
Solids Handling (not receiving cost-share)
- New Kent will continue to use the current solids handling plan where sludge is stored in aerobic tanks, then hauled to the Henrico County WWTP for dewatering and disposal. Future sludge holding capacity will be phased in as a function of influent flow, initially using the existing holding tank along with capacity in the converted secondary clarifiers and oxidation ditch.
Pumping Stations (not grant eligible)
- Plant Drain System and Non-Potable Water/Effluent Pump/Reclaimed Water Pump Station.
Reclaimed Water System (grant eligibility not applicable)
- For this portion of the project the County has been approved to receive $3.92 million under the FY 2009 Supplemental Stimulus Funding Loan Authorization (administered by DEQ's VA Clean Water Revolving Loan Fund Program). A 10.5-mile reclaimed water force main and improvements to the distribution system at the County's Chickahominy WWTP will be constructed to provide irrigation water to three end users with needs estimated at 82 to 123 million gallons per year.