Treating PFOA and PFOS at the Hatboro Wells
Advanced treatment facility supports strategic plan to protect water customers from long-term exposure to unwanted chemicals
Our Client’s Challenge
With an extensive service area covering 32 counties, Aqua Pennsylvania (Aqua) provides safe drinking water to an estimated 1.5 million customers across the state.
To maintain high-quality service, the utility undertook a strategic plan to proactively address the presence of unwanted per- and polyfluoroalkyl substances (PFAS) – in this case, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS). These manufactured chemicals can accumulate in the bodies of people repeatedly exposed to them over time, with unknown consequences.
Aqua’s Hatboro Wells #6 and #8, which produce a total flow rate of 420 gallons per minute, exhibited concentrations of PFOA and PFOS compounds that, although not above the then-current regulatory limits, required treatment to meet the company’s water quality goals.
Aqua selected Gannett Fleming to conduct water treatment process alternatives analyses and pilot testing and provide design, permitting, and bid- and construction-phase services for a new treatment facility that would remove PFOA and PFOS to levels below the detection limit.
Gannett Fleming performed technical evaluations comparing carbon contactors and ion exchange treatment units to determine an optimum solution for removing PFOS and PFOA compounds at the Hatboro wells. We also conducted other technical assessments to identify the preferred process wastewater disposal option, chemical disinfection alternatives, and single vs. double pumping arrangements.
Based on the results of the pilot testing, we designed a treatment facility equipped with ion exchange resin treatment units in a smaller building footprint and with lower capital, operating, and maintenance costs. It features:
- New pumps at the wells that allow for single pumping from the wells through the treatment units and then to the distribution system.
- Three separate chemical rooms.
- An external brine tank.
- Electrical and mechanical rooms.
Separate ammonium sulfate, sodium hypochlorite, and orthophosphate feed systems add necessary components to the treatment process in the required amounts. Additional large-diameter piping also was needed to provide adequate contact time for chlorine disinfection for both wells following treatment.
The project included demolishing the existing wells’ pumping and treatment stations and installing a pitless adapter at each, as well as conveyance infrastructure from the Well #8 supply to the proposed treatment facility at the Well #6 site. The two wells and proposed treatment station are situated in Blair Mill Park, home to the Hatboro Little League. Accordingly, the new raw water piping and treatment facility must respect five baseball fields and their related structures and parking areas.
Our firm detailed the demolition, designed the new treatment facility, and developed the construction sequencing for the project. Additional engineering services included:
Gannett Fleming also provided comprehensive permitting services for the project. Initially, this included developing a pilot testing protocol that required approval by the Pennsylvania Department of Environmental Protection (PADEP) before the one-year pilot test commenced.
The PADEP approved the pilot test report, which informed the basis of the design. We then prepared the Public Water Supply Permit Application, including design drawings and technical specifications, which led to the PADEP issuing the permit. We also addressed local Horsham Township permitting requirements for Aqua.
Finally, we assisted Aqua with project funding applications and provided support services during the bid and award phase of the project. Gannett Fleming is also providing construction-phase services for the project.
- Construction sequence staging maintains water service from one of the Hatboro wells during plant construction.
- New station structure houses ion exchange resin filters for PFOA and PFOS removal, required chemical feed systems, safety equipment, analyzers, and other appurtenances.
- Emergency generator provides backup power to maintain operations in the event of power failure.
Awards & Recognition
- Awards. Webpart is hidden
- Enhanced customer protection through the removal of PFOA and PFOS from the water.
- Optimized treatment and pumping processes to meet anticipated capacity requirements.
- Combined water treatment from two wells improves operational efficiencies.