Design and Construction Services for 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, 7, and 9. The Groundwater Treatment Plant treats 2,100 gallons per minute (gpm) with one filter out of service.
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 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 Supervisory Control and Data Acquisition (SCADA) system integration, site piping, and construction of a paved driveway and gravel access road along the perimeter of the residual filters.
Approximately 2,000 linear feet of 16-, 12- and 8-inch raw and finished water transmission main will be constructed based on the results of a routing study. These water mains connect Wells 6 and 7 to the new groundwater treatment facility and are sized for future flows from Well 9.