Training Field Road Groundwater Treatment Plant chatham, massachusetts The Town of Chatham selected Weston & Sampson to pilot, conduct a site selection study, and provide construction services for a new pressure filtration facility using Greensand Plus™ and granular activated carbon (GAC) filter media. The facility was designed to provide treatment for the removal of iron, manganese, and PFAS from the town’s existing groundwater Wells 5 and 8. The groundwater treatment plant will treat a maximum flow rate of 1.44-million gallons per day (mgd) using four ten-foot diameter greensand pressure filters and four (4) twelve-foot diameter GAC pressure filters. The treatment process chemicals include potassium hydroxide for pH adjustment, zinc pyrophosphate for corrosion control, sodium hypochlorite for oxidation and disinfection, and sodium thiosulfate for dechlorination. The oxidation and removal of iron and manganese will precede PFAS removal in the GAC pressure filters. This requires the addition of sodium thiosulfate to dechlorinate the greensand filter effluent, preventing the accelerated exhaustion of GAC media from high free chlorine concentrations. Design elements of the treatment facility include a bathroom, laboratory area, fully automated Supervisory and Data Acquisition (SCADA) system integration, site piping, and construction of a paved driveway. The bottom floor contains a pipe gallery and two 100,000-gallon backwash basins used for the retention of filter backwash waste which will be recycled into the plant’s raw water intake. The existing Well 5 and 8 buildings will remain in place, with new well pump motors installed to overcome the increased head loss of the treatment process and supply adequate system pressure. The new water treatment plant will produce PFAS-free water, with reduced levels of iron and manganese.

The Town of Chatham selected Weston & Sampson to pilot, conduct a site selection study, and provide construction services for a new pressure filtration facility using Greensand Plus™ and granular activated carbon (GAC) filter media.

The facility was designed to provide treatment for the removal of iron, manganese, and PFAS from the town’s existing groundwater Wells 5 and 8. The groundwater treatment plant will treat a maximum flow rate of 1.44-million gallons per day (mgd) using four ten-foot diameter greensand pressure filters and four (4) twelve-foot diameter GAC pressure filters.
The treatment process chemicals include potassium hydroxide for pH adjustment, zinc pyrophosphate for corrosion control, sodium hypochlorite for oxidation and disinfection, and sodium thiosulfate for dechlorination. The oxidation and removal of iron and manganese will precede PFAS removal in the GAC pressure filters. This requires the addition of sodium thiosulfate to dechlorinate the greensand filter effluent, preventing the accelerated exhaustion of GAC media from high free chlorine concentrations.

Design elements of the treatment facility include a bathroom, laboratory area, fully automated Supervisory and Data Acquisition (SCADA) system integration, site piping, and construction of a paved driveway. The bottom floor contains a pipe gallery and two 100,000-gallon backwash basins used for the retention of filter backwash waste which will be recycled into the plant’s raw water intake.

The existing Well 5 and 8 buildings will remain in place, with new well pump motors installed to overcome the increased head loss of the treatment process and supply adequate system pressure. The new water treatment plant will produce PFAS-free water, with reduced levels of iron and manganese.

Location

Chatham, MA

Services

Water