Tests show high radiation levels in Poolesville well
More testing needed to determine federal compliance
One of Poolesville's wells may need to be taken out of use due to elevated levels of radiation-emitting elements, according to preliminary test results.
The town has been testing its water since the Maryland Department of the Environment detected elevated alpha-emitting radionuclide levels in three of Poolesville's nine wells — 4, 7 and 9/10 — in November 2005. All community water systems were tested to ensure compliance with new U.S. Environmental Protection Agency standards.
Alpha-emitting radionuclides, such as plutonium, polonium, radon, radium and uranium, are naturally occurring compounds that emit alpha radiation when they decay, according to Kathy Mihm, a geologist with S.S. Papadopoulos and Associates, which has been independently testing the town's water. Adjusted gross alpha is a measurement of all alpha activity except for uranium and radon, which are measured separately.
Alpha radiation is not radioactive, although those who drink water with high levels of alpha emitters over an extended period of time may develop an increased risk of cancer, according to the EPA.
Well 10 averaged 15.22 picocuries per liter (pCi/L) of adjusted gross alpha activity based on three quarterly samples taken in 2008, according to Mihm. The maximum contaminant level for adjusted gross alpha is 15 pCi/L.
"If you are over you have a slight increase in risk, but it's still a very low risk," Nancy Reilman, chief of MDE's Safe Drinking Water Act Implementation Division, said at Poolesville's Monday night commissioners meeting.
Preliminary annual averages for Wells 7 and 9 and combined Well 9/10 were below the maximum contaminant level, Mihm reported at the meeting. Well 4 was found to be in compliance in 2006.
"They [the EPA] change the requirements frequently, and we've been taking a very, I believe, proactive approach in the town," Commission President Eddie Kuhlman said. "This is hopefully the beginning of the culmination of these tests."
A fourth quarterly sample is still needed to determine whether Well 10 is in compliance, Mihm said. MDE is expected to make its final determination based on its own sampling early next year, she said.
The elevated levels in Well 10, which was taken out of use in August 2007, could be the result of an analytical error, Mihm said. If MDE finds that the well is not in compliance, it could be permanently taken out of service or its water blended with Well 9, she said.
About 30 residents attended the meeting, and several expressed concerns that the town's water could be dangerous to residents.
"We're not supposed to have any of this in our water," said Stephanie Skenderis of Poolesville.
The wells were all under the maximum limit of 30 micrograms per liter (µg/L) for uranium based on four quarterly samples, according to Mihm. Well 10 had the highest average, 27.17 µg/L. Poolesville has the highest uranium levels of all of the state's community water systems, Reilman said.
Radium was also under the maximum of 5 pCi/L, Mihm said.
Radon in the town's 10 wells ranged from 400 to 2,700 pCi/L, Mihm said. The EPA's proposed standards for radon in drinking water would set maximum contaminant limit of 4,000 pCi/L for towns that implement an effective radon public outreach program and a maximum limit of 300 pCi/L for towns that do not.
Mihm said she did not recommend that the town take any action until the EPA establishes radon standards.