Pudding Hill Water Treatment Plant begins operation

posted 5/13/2024

The new Pudding Hill Water Treatment Plant has pumped its first million gallons of water into the city’s drinking water system since it came online earlier this month, utilizing the Pudding Hill aquifer for the first time since 2019. Once fully operational, which could be as early as next week, the treatment plant is capable of adding a million or more gallons of water daily into the city’s water system, providing 40% of the city’s daily water needs.

“Pudding Hill puts us back where we need to be with plenty of water,” said Community Services Director John Storer. “Unless we have a substantial region-wide massive drought, we should be fine meeting all city demands moving into the future.”

The city will be providing tours of the new water treatment plant during its Open House on Saturday, May 18, from 11 a.m. to 2 p.m.

Some of the mandatory water restrictions in recent years were due to the Pudding Hill aquifer being offline, where the city had to rely on other aquifers during periods of drought. The re-utilization of the Pudding Hill aquifer will allow the city’s other drinking water aquifers to rest and recharge. Last week, the city’s groundwater consultant provided an overview of Dover’s aquifers, which can be viewed here.

The city voluntarily took the Pudding Hill aquifer offline in 2019 when its sentinel monitoring wells detected plumes of PFAS contaminants; however, no PFAS were ever detected in the drinking water pumped from the wells. PFAS seeped into the ground from the former auto recycling plant off Knox Marsh Road that Schnitzer Steel Industries Inc. now owns. As a responsible party, the firm is paying a significant portion of the costs to construct the new treatment plant, with the balance funded by a state PFAS grant.

The Pudding Hill Water Treatment Plant meets and exceeds the U.S. Environmental Protection Agency’s new drinking water standards released last month that lowered the threshold of actable limits for PFAS class chemicals.

The plant utilizes granular activated carbon (GAC) to remove all observed PFAS levels. The plant was designed to add additional filtration should there be an issue with a specific PFAS compound or other chemicals. PFAS are perfluoroalkyl and polyfluoroalkyl substances, which have been used in products like Teflon, Goretex, and firefighting foam. The city had begun testing GAC filters in 2018 on about 10 different PFAS compounds, and all were brought down to non-detect levels, noting that GAC is also robust with emerging PFAS chemicals now being investigated.

“The new water treatment plant will be able to treat all PFAS compounds from the Pudding Hill Aquifer to EPA’s target goal of zero, or non-detectable per current laboratory standards,” Storer said. “Outside of Pudding Hill, the city has not experienced any PFAS issues requiring treatment, highlighting the importance of protecting our aquifers through land conservation or zoning protections.”

Groundwater from the Pudding Hill aquifer will be pumped to the treatment plant and treated with caustic soda (sodium hydroxide) and chlorine (calcium hypochlorite). The pretreated water will be filtered through three Greensand Plus filters to remove iron and manganese. Next, hydrogen peroxide is added to the filtered water entering the two ultra-violet light reactors for the advanced oxidation process (AOP) to remove 1,4-dioxane and MTBE (methyl tert-butyl ether). After AOP, the water will be filtered through three pairs of GAC filters to remove PFAS.

For more information, contact Community Services at 603-516-6450