Water Quality Study and Professional Engineering Services
Town of Medfield • Medfield, MA
Solution Overview
Client:
Town of Medfield
Business Challenge:
- The municipality wanted to take a proactive and holistic approach to water quality management while keeping an eye on the emerging contaminant of per- and polyfluoroalkyl substances (PFAS)
Solution:
- Chemical pre-treatment
- Peak filter loading rate
- 2.2 million gallons per day (MGD) WTP design
- Provisions to integrate future PFAS treatment
Results:
- Initial PFAS screenings completed
- PFAS concentrations above 10 parts per trillion (ppt) at Wells 1 and 2 and lower levels of PFAS at Wells 3, 4, and 6
- Approved feasibility study of PFAS treatment at Wells 1, 2, and 6
Challenge
The Town of Medfield needed to conduct water quality studies at several of its public water supplies, and based on results, would likely need professional engineering services for the design and construction phases of a water treatment system in a proactive approach to PFAS management.
Solution
The Town of Medfield engaged Environmental Partners (EP), Apex Companies’ Infrastructure Solutions platform to assist with both a water quality study and engineering services. The study focused on establishing the source water levels of iron and manganese to develop the scope for a pilot treatability study. During the study, it was found that Well 3 had higher source concentrations of iron and manganese. A chemical pre‑treatment of sodium hypochlorite and sodium hydroxide, GreensandPlus, or LayneOx for filter media, and a peak filter loading rate of up to 9 gallons per minute per square foot (gpm/sf) was proposed. Upon acceptance, a design for the 2.2 MGD WTP for Wells 3 and 4 was completed in March of 2021. The layout includes chemical storage rooms, process area for the pressure filter vessels and air scour blower, a below grade filter backwash waste tank, a backwash waste pump system to pump residuals to the municipal sewer system, a laboratory/control room, and electrical/mechanical rooms. Provisions were made to integrate future PFAS treatment, if needed.
Results
In February 2021, the Town of Medfield completed their initial PFAS screenings of Wells 1, 2, 3, 4, and 6. Results indicated PFAS concentrations above 10 ppt at Wells 1 and 2 and lower levels of PFAS at Wells 3, 4, and 6. As the designs for these wells accounted for future PFAS treatment, the Town approved a feasibility study of PFAS treatment at Wells 1, 2, and 6. The findings and recommendations are currently being evaluated by the Town.