Innovative Biological Filtration System Design and PFAS Removal
Tighe & Bond worked with the Littleton Water Department on a new water treatment plant and replacement wellfield at Whitcomb Avenue in Littleton, MA. The Town of Littleton’s Whitcomb Avenue Wells produce groundwater with iron and manganese concentrations at or above the standards for aesthetics. To mitigate iron and manganese in the Town’s wells, Tighe & Bond performed a pilot study that recommended treatment with traditional GreensandPlus Filtration as the primary treatment method.
When Littleton’s Well 5 tested positive for PFAS6 above the MA MCL a second pilot study was conducted using biologically active pressure filtration for the removal of iron and manganese ahead of PFAS treatment. The pilot studies determined biological filtration of iron and manganese works well with either IX or GAC filtration for PFAS6. The pilot study provided information for the Water Department’s Well No.1, Well No.3 wellfield, and Well No. 5. The project included the construction of a new wellfield to replace the existing wellfield at Well No. 3 in order to increase the capacity of the source and complete modifications to the existing Well No.1 pump station. Raw water from Well Nos.1 and 3 will be pumped to the new water treatment plant located across Whitcomb Avenue from the well site. Raw water from Well No. 5 was pumped to the new WTP through a new 3-mile transmission main.
The new 1.8 MGD water treatment plant design included chemical addition to the raw water for pH adjustment and the addition of air to increase the dissolved oxygen levels for the biological filtration process. Water is then disinfected using medium pressure UV lamps before filling the cast-in-place clearwell. High head centrifugal pumps will then pump the water from the clearwell through GAC filters for PFAS removal and receive additional chemical treatment including disinfection with chlorine and final pH adjustment before being conveyed to the distribution system.
Tighe & Bond provided pilot testing, design, permitting, bidding, and construction services for the Whitcomb Avenue Wells Water Treatment Plant.