Petroleum leak at Brookside affects neighboring well

WILTON — Cleanup for a petroleum leak in underground storage tanks at Brookside Mini Mart on Gibbons Highway — which affected the water supply of a neighboring business — is under way with a new water well scheduled to be drilled this month.

In the past six months, the state has allocated more than $200,000 in funds to help to clear the area of 626 Gibbons Highway of petroleum contamination caused by a malfunction in one of Brookside’s underground storage tanks.

The issue was first discovered in July, when Premier Concrete, a business to the Southeast of Brookside, notified the state’s Department of Environmental Safety of a petroleum odor in its well water and testing that showed petroleum compounds, according to DES Public Information Officer Jim Martin.

DES did confirmation sampling at the end of July, and confirmed there were several petroleum compounds that were above the ambient ground water quality standards.

In the beginning of September, DES began investigating the origin of the petroleum, starting with the neighboring store and attached gas station, Brookside Mini Mart. DES conducted an initial site characterization on the Brookside property, and determined it was indeed the store’s underground storage tanks that were causing the contamination. The cause was determined to be a faulty tank.

In November, DES removed the underground petroleum storage tanks, and 1,600 tons of petroleum impacted soil from the surrounding area, and then began to test other wells in the area to see if the contamination had spread beyond Premier Concrete’s well.

All wells within 1,000 feet of the contamination were tested, including five other wells to the southeast of Brookside, but Premier Concrete’s was the only well found to be affected.

One of the reasons for that could be that the Premier Concrete well was the only dug well, as opposed to drilled into the bedrock.

“Those are much more susceptible to surface contamination than bedrock well, which are drilled much deeper,” Martin said of dug wells. “They are much shallower wells.”

It was also the closest well to the contamination site.

In January, DES authorized the drilling of a replacement well for Premier Concrete, scheduled to be put in this month. The cost of both the installation of the well and the remediation costs of cleaning up the petroleum leak will be paid for by DES’s petroleum remediation fund, according to Martin. All gasoline imports pay a fee towards the fund, which is used as an insurance policy for these types of leaks or other accidents, he said.

Because the petroleum did not affect any other deep-drilled wells adjacent to the property, DES does not anticipate long-term affects to the area’s groundwater as a result of the leak, said Martin. DES will continue to drill monitoring wells in the upcoming months to continue to test for contamination.

Currently, Brookside is not subject to any fines or penalties concerning the leakage, said Martin, although investigation into the incident is still ongoing.

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