Construction Complete at Littleton Water Treatment Plant
On September 19, the Littleton Electric, Water, & Light Departments (LELWD) hosted a ribbon cutting ceremony for the Whitcomb Avenue Water Treatment Plant (WTP). Tighe & Bond provided pilot testing, design, permitting, bidding, and construction services for the project, which recently finished construction.
When fully operational, the Whitcomb Avenue WTP will be the first in Massachusetts to utilize biologically active pressure filtration for the removal of iron and manganese ahead of granular activated carbon (GAC) for the removal of PFAS. The iron filters are now online, the manganese filters are expected to be online by the end of September, and the PFAS filters are expected online in November.
The Town-owned Whitcomb Avenue Wells produce water that is high in iron and manganese, which can affect the taste and appearance of tap water. In response to water quality concerns, Tighe & Bond initiated a comprehensive pilot study for the removal of these minerals. Their findings recommended the implementation of traditional GreensandPlus Filtration as the primary treatment method to address the elevated iron and manganese levels in the Town’s wells.
After Littleton’s Well 5 tested positive for PFAS6 above the Massachusetts Maximum Containment Level (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 will be pumped to the new WTP through a new 3-mile transmission main.
The new 1.8 Million Gallons per Day (MGD) water treatment plant design incorporated chemical addition for pH adjustment and air injection to enhance dissolved oxygen levels for the biological filtration process. The treatment process continued with water disinfection via medium-pressure UV lamps before entering the cast-in-place clearwell. The water is then transported through GAC filters designed to remove PFAS contaminants. The treated water then undergoes further chemical treatment, including chlorine disinfection and final pH adjustment, before being distributed to the community.
The project cost approximately $20.25 million to construct, finishing $4.2 million under budget. With the Whitcomb Avenue Water Treatment Plant complete, the Town of Littleton and its residents will benefit through improved quality of drinking water and the removal of iron, manganese, and PFAS.