Watewater Treatment Facility Poised to Meet Future Nutrient Standards
Falmouth, Maine
Facility awarded the “2009 Engineering Excellence Award” from the Maine Chapter of the American Council of Engineering Companies.
As a long time consultant to the Town, Falmouth retained Wright-Pierce to upgrade their aging, 40-year water pollution control facility. The secondary treatment process had remained virtually unchanged since conception and demanded immediate attention. Consideration of future discharge standards requiring nutrient removal accelerated as the Maine Legislature tasked the Department of Environmental Protection to begin the long process of establishing nutrient standards for Casco Bay. The sensitivity of the current discharge required careful consideration of what those future standards may be, how they might be addressed by an upgrade, and what provisions should be made for even more stringent standards in the future.
Faced with significant site constraints, Wright-Pierce conceived a design which incorporated significant existing infrastructure into the new treatment scheme which aved the owner hundreds of thousands of dollars in construction costs and capitalized on past investments.
The new treatment system employed an Anaerobic-Anoxic-Oxic (A2O) process with a biological selector designed to improve present day water quality characteristics and provide for advanced nutrient removal. The result was a facility poised to serve the future sewered growth needs of the community and one that produces exceptional quality effluent. Removal of the conventional pollutants is improved by 40% and nutrient removal is meeting the design goals of 8 mg/L total nitrogen and 1 mg/L phosphorus. Space has been preserved within the process configuration to allow easy expansion should even more stringent requirements be established in the long term. Along with increased treatment efficiency and advanced nutrient removal, the upgraded facility has reduced monthly electrical consumption on average by 40%.
This $7M facility was constructed under the original contractors bid price, practically unheard of in a major retrofit project.
The upgraded facility is one of only a few advanced treatment facilities in Maine poised to meet future nutrient discharge standards. Saving energy, improved treatment efficiency and positioned for the future, the Town has become a state leader in environmental stewardship.
Nutrient Limits Are on the Horizon
Since the Clean Water Act of 1972, secondary wastewater treatment has been the norm of the industry. Over the past several years, state and federal regulators have been focusing on water quality-based standards and nutrient criteria. Phosphorous standards have become common for many fresh water discharges, and even more stringent standards are imminent for many facilities throughout New England. Nitrogen standards have been in effect for several years in Connecticut, due to Long Island Sound’s water quality problems; in Rhode Island due to water quality issues in Narragansett Bay; and in places like Cape Cod, due to many sensitive embayments. However, nitrogen standards are less common in the other New England states.
Looking ahead, every New England state is developing nutrient criteria, and more stringent nitrogen standards will likely be established for any discharge that impacts sensitive coastal estuaries and embayments, and more stringent phosphorus standards for any discharge that impacts fresh waters. In Connecticut, the state is in the process of implementing new phosphorus removal standards for facilities with fresh water discharges. In the near future, advanced wastewater treatment for nutrient removal will be as common place as secondary treatment has been since 1972.
The good news is that more stringent nutrient standards do not necessarily have to translate to more costly operations. Our lead newsletter article about the Falmouth Wastewater Treatment Facility illustrates how a progressive community met stringent nutrient criteria and at the same time reduced operation costs.
If you are facing stringent nutrient criteria, Wright-Pierce can help. Feel free to contact John Braccio, P.E. at 888.621.8156