Virginia Department of Environmental Quality - Chesapeake Bay Program
Water Quality Improvement Fund Match (Tappahannock Wastewater Treatment Plant Upgrade for Nutrient Removal)
Project Description as Proposed:
This project (WQIF Agreement #440-S-08-10; $4,710,623 grant) involves retrofit of Tappahannock’s existing 0.8 MGD oxidation ditch treatment process with enhanced nutrient reduction technology (NRT). $811,026 of this WQIF grant will be used as State General Fund match for Virginia’s Coastal Zone Management Program.
The Tappahannock WWTP is located in Essex County, on the south shore of the tidal Rappahannock. As a Rappahannock Basin “significant discharger,” this plant must comply with total nitrogen and total phosphorus waste load allocations as required in two State Water Control Board regulations: (1) Water Quality Management Planning Regulation (9 VAC 25-720); (2) Chesapeake Bay Watershed General Permit Regulation (9 VAC 25-820). The compliance period for the nutrient allocations begins on January 1, 2011, and limits this facility’s discharged loads to 9,746 lbs/yr of nitrogen and 731 lbs/yr of phosphorus. The retrofitted facility will reduce the nitrogen load by about 29,000 lbs/yr and the phosphorus load by about 1,700 lbs/yr at full design flow. This retrofit will be a major contributor to the overall nutrient reduction efforts in the Rappahannock Basin, along with several other wastewater plant upgrades and nonpoint source runoff control projects. More information about DEQ’s WQIF grant program is accessible at: http://
Match to Virginia CZM Program grant from NOAA Only - $816,026
John Kennedy, 804.698.4312; John Kennedy@deq.virginia.gov
10/1/2009 - 9/30/2010; Project Completed
Final Product Received:
Project Summary Provided by Grantee:
Retrofitting the Tappahannock wastewater treatment plant with enhanced nutrient removal (ENR) technology under Water Quality Improvement Fund (WQIF) Grant #440-S-08-10 was completed during this reporting period, with final grant reimbursement authorized 7/20/10. Construction began in April 2008 and the Certificate to Operate was issued 7/23/10.
The final grant amount was $4,551,827 in WQIF cost-share (original grant = $3,061,604; twice revised by contract modifications), which far exceeds the $768,311 in State General Funds needed for CZMP match.
The completed scope of work consists of the following:
- Activated Sludge Treatment: A new anoxic basin was constructed to include anoxic mixing, to serve as the first stage of a 4-Stage Bardenpho (nitrification/denitrification and phosphorus reduction) process. The existing oxidation ditch was converted into the other three stages. Retrofitting also included new nitrate recycle pumps, anoxic mixers, fine bubble diffusers and aeration blowers.
- Recycle Pump Station: A new recycle pump station was added to return nutrient rich streams to the equalization basin for bio-augmentation.
- Tertiary Filtration: Deep-bed tertiary filters were installed to achieve total suspended solids and particulate phosphorus removal.
- Aerobic Digestion and Sludge Dewatering System: A digester with associated blowers and coarse bubble diffusers and a new belt filter press were installed to handle the additional solids produced by the ENR process.
- Additional emergency/back up power was provided for the new equipment, and the existing Supervisory Control and Data Acquisition (SCADA) system was modified to aid in controlling the new ENR processes.
- Chemical Feed Systems: Including new sodium/magnesium hydroxide (supplemental alkalinity) storage; a new supplemental carbon storage and feed system; existing alum storage and feed systems were improved; aluminum salt addition provided prior to the secondary clarifiers for phosphorus removal; and, a new polymer system to aid sludge settling.
At full design flow (800,000 gallons per day), the retrofit project will reduce the annual nitrogen discharge from the Tappahannock plant by about 29,000 lbs/yr and the phosphorus load by 1,700 lbs/yr. Additional details on the retrofit project are accessible at this weblink: http://www.deq.virginia.gov/bay/wqif/Tappahannock.html
Disclaimer: This project summary provides the federal dollars initially awarded to the grantee. Due to underexpenditure or reprogramming of grant funds, this figure may change. For more information on the allocation of coastal grant funds, please contact Laura McKay, Virginia Coastal Program Manager, at 804.698.4323 or email: Laura.McKay@deq.virginia.gov
A more detailed Scope of Work for this project is available. Please direct your request for a copy to Virginia.Witmer@deq.virginia.gov