The Chester River Hospital’s most recent attempt to clean up a 25-year-old heating oil spill may have caused the August 3 shutdown of the town’s newest drinking well on Horsey Lane, said Chestertown Utilities Manager Bob Sipes at Monday’s council meeting. He said redeveloping Well 9 could cost the town upwards of $55,000.
With approval from Maryland Department of Environment, the hospital injected 6,000 pounds of carbon dioxide, and later oxygen, into the Aquia Aquifer to grow anaerobic bacteria–in an attempt to degrade and break down any remaining heating oil.
The injections occurred between July and September of last year–but the town was only made aware of the injections this April.
Sipes said the presence of iron bacteria in the well, which caused Well 9 to malfunction, is a bi-product of introducing oxygen into the aquifer. He said the buildup of iron bacteria made the well pump inoperable.
“The purpose was to grow bacteria in the aquifer and convert the hydrocarbon (heating oil) into something else,” Sipes said. “They were trying to start a biological action in the aquifer.” He said the procedure “apparently didn’t work.”
Sipes said the town just learned of the injections in April when the town received a copy of a request the hospital made to MDE in March to end the hospital’s cleanup program, which entailed pumping contaminated groundwater into recovery wells, treating it, and discharging the treated water into the Chester River.
The town responded in June with a letter to MDE and the hospital—critical of ending the cleanup program and expressing concern of the potential unintended consequences of growing bacteria in the aquifer.
“We said “how dare you do this” because the oxygen injections put us at risk for iron and anaerobic bacteria being introduced into the aquifer and impacting our well field,” Sipes said. He also said it was the duty of MDE to inform the town of any possible impact from the oxygen injections before it was approved.
The hospital’s remediation program had been ongoing since 1991 when nearly 7,000 gallons of home heating oil spilled from an underground tank, forcing Well 8 to be shut down.
The hospital’s request to MDE this March cited a $50,000 annual cost that was reclaiming less and less heating oil. In the letter was a reference to the oxygen injections that occurred last year, Sipes said.
“That was the first we’d heard about the oxygen injections,” Sipes said in an interview with the Spy on Tuesday.
Sipes said it was not conclusive that the introduction of oxygen into the aquifer caused the buildup of iron bacteria in Well 9, but he said it was “suspicious” since it is the first time he’s ever known of a well in Chestertown to test positive for the two bacteria. He said anaerobic and iron bacteria can only be present if oxygen is introduced in the water.
He said a preliminary test on Well 9 showed resistance from 35 to 250 feet. “[We suspected] iron in the well,” Sipes said. A “Bart Test” was conducted and lab results came back positive eight days later for iron and anaerobic bacteria.
Sipes also couldn’t understand why the hospital ended the cleanup program after the hospital’s consultant, Earth Data, said that the “natural ground water flow is towards… Chestertown’s well field.”
Sipes said it is very possible the bacteria kept growing long after the oxygen injections stopped. He said vigilant testing will be needed to make sure the other wells have not been contaminated.
He said protecting Well 9 is made more difficult because it draws from an unconfined aquifer, the Aquia, where contaminated water from the hospital could potentially seep through or be drawn through permeable layers of sandy clay. The Magothy Aquifer, where the town also draws drinking water, is deeper and buffered by hard clay formations that better defend the aquifer against contamination.
The town now has to hire a geologist and a well driller to redevelop the well. Tests will have to be run every day during the redevelopment “so we can evaluate the well field,” Sipes said. He said the experts will be able to “determine if oxygen was introduced into the aquifer and caused the buildup of bacterial in Well 9.”
He said he hoped that the hospital was not responsible for the damage to Well 9 and was not looking for a scapegoat.
“We don’t want to know what we can put off on somebody else,” Sipes said. “If it’s most likely that this wasn’t caused by the hospital…we’re perfectly ok with that.”
“But a worst case scenario is [the hospital] established iron bacteria in the aquifer that stretches from the hospital to the well.”
If contamination did occur from the hospital, Sipes is concerned the problem could reoccur after the well is fixed. He said Well 9 originally cost $450,000 to install around six years ago.
The town has sent a letter to MDE and the hospital to request the hospital resume its cleanup program, which ended in July with approval from MDE.
Sipes assured the Council on Monday that the town’s drinking water is safe and was never affected by the shutdown of Well 9.