The city of Fairhope, Ala., population 15,000, is nestled along Mobile Bay. Part of the fastest-growing county in Alabama—and one of the fastest-growing counties in the U.S.—it also receives more rainfall than any other U.S. metropolitan area and is located in an environmentally sensitive ecosystem: the Mobile Bay estuary. The growing population combined with environmental concerns make wastewater treatment in Fairhope a challenge.
While Fairhope’s inflow and infiltration program reduced groundwater intrusion into its sanitary sewer system, as well as peaks occurring during extreme rainfall events, over the past decade the biochemical oxygen demand at the 4-million-gal-per-day Fairhope Water Resource Recovery Facility (WRRF) had increased by 50%, and total suspended solids had increased by a similar amount during a three-year span. Increased loadings exceeded the facility’s original design parameters, reducing its available treatment capacity.
Fairhope Water and Sewer Superintendent Dan McCrory saw the need for a project that would address these issues. He advised the mayor of Fairhope and its city council to find a solution. As a result, Fairhope partnered with Volkert Inc., a Mobile, Ala.-based consulting firm, on a WRRF improvement plan to enhance the treatment of collected wastewater so it could be discharged into Mobile Bay. The project aimed to maintain permit compliance at the WRRF; address the reduced facility capacity; improve efficiencies; and enhance effluent quality through nutrient removal and filtration.
The WRRF’s screening removal and aeration systems were upgraded to foster nutrient removal. Clarification, ultraviolet disinfection and solids digestion systems also were upgraded. The project converted the WRRF’s biological treatment process from extended aeration to an aerated anoxic process. Modifications to the SCADA system also were necessary in order to incorporate new equipment and technology. Headworks screening efficiency was increased as well. Noise and odor reduction were considered, with the project team providing for equipment, such as noise-reducing sound enclosures, and odor-avoidance measures.
The upgrades are notable in that they went beyond current regulatory requirements—while some improvements were needed to address capacity issues at the WRRF, the decision to install a tertiary treatment system was a result of Fairhope’s dedication to maintaining the Mobile Bay estuary’s water quality.
The $11.8 million project began in June 2012 and was completed in August 2015. It came in more than $100,000 under the original construction contract amount. The city of Fairhope and Volkert Inc. were awarded the 2016 Partners for Environmental Progress Environmental Stewardship Award for their work on the project.
“The outstanding success of this project was due to the shared objectives and cooperative spirit of Fairhope Mayor Tim Kant and the city council members; Fairhope Water and Sewer Superintendent Dan McCrory, along with WRRF Manager Tim Manuel and his operations staff; the contractor J&P Construction Co. and its subcontractors; the equipment manufacturers and their representatives; and the Volkert design and construction team,” said Tim E. Patton, P.E., principal in charge and vice president for Volkert.
McCrory also was pleased with the project’s results: “I would like to thank the Volkert team for their efforts to successfully design and implement a plan for completing the desired treatment upgrades, while also maintaining existing operations and permit compliance to a facility that has limited space and is located immediately adjacent to a tourist downtown area,” he said.