“DOVER — The city stopped using its most abundant source of drinking water after it found an increasing level of contaminates inside in one of its drinking water wells.
But city officials stressed drinking water wells were shut off well before it reached, and now exceeded, the EPA recommended advisory levels of safe drinking water. They also confirmed the city has an adequate supply of water for the near term.
The problem well draws from the Pudding Hill Aquifer located near the former Madbury Metals recycling site near Knox Marsh and Pudding Hill roads. Community Services Director John Storer said the aquifer has numerous monitoring wells, which he described as sentinels guarding the city’s drinking water, which picked up on the migration of the contaminants of PFOA and PFOS.
City officials and the consultants contracted to monitor the drinking water have been keeping watch on contaminant levels at the monitoring sites and in the drinking wells, Storer said. When the Ireland Well in the Pudding Hill Aquifer recorded a concentration of 48 parts per trillion of PFOA and PFOS parts per trillion on June 28, the decision was made stop drawing water from the well, Storer said.
On Monday, City Manager Michael Joyal informed the City Council that test results recorded earlier that day exceeded the EPA’s health advisory level of 70 parts per trillion, which the federal agency revised in 2016. According to the EPA, a level of 70 ppt provides ‘a margin of protection from a lifetime of exposure to PFOA and PFOS from drinking water,’ including ‘the most sensitive populations.’
‘We have notified and will be seeking assistance from N.H. Dept. of Environmental Services given these recent findings,’ Joyal wrote. ‘We will also be meeting with our aquifer consulting experts and water utility engineers to consider treatment options for expeditiously and safely returning the wells drawing from the Pudding Hill aquifer back into production.’
Joyal noted the city discontinued the use of the Griffin Well in late 2015 and has not restarted the well after monitoring confirmed the presence of perfluorinated compounds: PFOA, PFOS and PFHpA…
Storer said the Ireland Well had recently been recording levels of between 6-10 ppt. He said while he would love to have zero level, it is just not realistic. Even the rain would likely have a 6-10 ppt level of contaminants, he said.
Storer said a recently dug well, known as Dover Pudding Hill 1 (DPH1) in the Pudding Hill Aquifer, was shut off as a precautionary measure until hydrologists can confirm that using the well isn’t sucking the plume towards it.
The average daily water usage in the Garrison City is about 2.5 million gallons of water a day, with a maximum demand of nearing 4 million gallons a day. When online, the Pudding Hill Aquifer can provide about 1 million gallons of water per day, Storer said. Still, without Pudding Hill, the city has a supply capacity of approximately 5 million gallons of water a day, Storer said.
Dover is in the planning phase of bringing a well online at Willand Pond and creating interconnection system with Somersworth that would allow a sharing of water in times of need. The interconnection plan still needs approval from both Dover and Somersworth City councils, Storer said.”
Read the full article by Brian Early