Chatham Groundwater Treatment Plant
The Town of Chatham selected Weston & Sampson to pilot, conduct a site selection study, design, and provide construction services for a new pressure filtration facility utilizing Greensand PlusTM filter media. The facility was designed to provide treatment for the removal of iron and manganese for the town’s existing groundwater Wells 6 and 7 and provide for future expansion of the water treatment plant to treat Well 9. The Groundwater Treatment Plant will treat 1,400 gallons per minute (gpm) with one filter out of service and ultimately be expanded to 2,100 gpm.
The treatment process chemicals include potassium permanganate, sodium hydroxide for pH adjustment of the treated water, an ortho/polyphosphate blend for a corrosion inhibitor and sodium hypochlorite for disinfection and oxidation. The plant includes a 60,000-gallon in-plant potable clearwell for contact time and backwash supply. The included forced draft steel aerator strips carbon dioxide in the raw water prior to pressure filtration; this aerator will reduce carbon dioxide from 115 mg/L to less than 48 mg/L in order to raise the raw water pH to approximately 7.0.
Design elements of the treatment facility include a bathroom, laboratory area, fully automated SCADA system integration with the existing distribution system including two other active wells, site piping, and construction of a paved driveway and gravel access road along the perimeter of the residual sand drying beds. MEP systems featured a multi-zone hydronic heating served by a high-efficiency gas fired condensing boiler, dedicated laboratory and chemical exhaust systems. The SCADA room has a dedicated cooling system and the main treatment hall is heated, ventilated and dehumidified to reduce condensation from forming in the water treatment pipes and equipment.