An underground storage tank that was removed from the former Shell station at the corner of Madison and Harlem streets spilled potentially dangerous toxins into the soil and groundwater, according to state records, but there appears to be little threat to the public.

Records maintained by the Illinois Environmental Protection Agency show that regulators first became aware of a leaking underground tank at 7201 Madison St. in late 2005, though a spokeswoman for the office said pollutants may have been discovered as early as 2002. After the fueling station closed last year and the site was put on the market in May, the property owner removed the faulty underground tank. John Robbins, project manager for owner Equilon Enterprises in Naperville, said it was during that extraction that the company reported another contamination “incident” to the Illinois EPA, however, there’s no evidence that any additional toxins had been released.

“It does not indicate that a new release had occurred, but more a re-reporting of the 2005 incident,” Robbins said.

Scott McGill, the Illinois EPA official overseeing the cleanup, did not return a phone call seeking comment.

Maggie Carson, a spokesperson for the IEPA said it appears the cleanup efforts were successful and the contaminants pose no risk to the public.

“Everything seems to be under control and properly managed,” Carson said. “The IEPA is satisfied with the remediation.”

Soil and groundwater analysis of the site was turned over to the village and presented to commissioners March 24 as part of a discussion on whether to enter into an indemnification agreement with Equilon Enterprises. In part, the agreement allows Equilon to delay immediate groundwater remediation while the village prohibits the installation of wells for the purpose of collecting drinking water. Also, in the event that the contamination leached into the soil underneath roadways and sidewalks, the agreement allows the village to collect any cleanup costs from Equilon.

In voting unanimously to approve the agreement with Equilon, commissioners were assured by village staff that the municipality would be held harmless with respect to cleanup costs and other potential liabilities.

Equilon, a joint venture between Shell Oil Company and Texaco Inc., cleaned the site in compliance with environmental standards for residential property as opposed to the standards used to remediate industrial or commercial properties. This required a greater level of remediation and was not required of Shell, said Robbins, but the company is committed to doing a thorough job.

“It’s a stricter regulation. It has nothing to do with the potential development of the site,” Robbins said.

Records of state soil samples show unacceptable levels of benzene and methyl tertiary butyl ether, or MTBE, which is a gasoline additive, at the site. Groundwater analysis at the site between 2005 and 2007 also show elevated levels of benzene and MTBE.

However, said Carson, more recent samplings suggest Equilon has successfully removed the toxins.

Because the village receives its drinking water from the city of Chicago, Village Administrator Mike Sturino said there is no reason to believe the toxins will harm the local water supply. In a memo prefacing the indemnification agreement for council members, Sturino encouraged elected officials to vote in favor of what the state EPA office calls a “tiered approach” to hazardous waste cleanup, which accounts for various levels of remediation depending on the future use of the property.

“The village has previously entered into agreements with property owners regarding leaking underground storage tanks,” Sturino said in his memo. “Environmental remediation of [these] sites may be fashioned around the current or proposed uses; this agreement contemplates this tiered approach to remediation. The Illinois and U.S. EPA authorize and encourage such agreements.”

Equilon sought to reach this agreement with the village, and Sturino speculated it was part of a marketing effort to make the lot more attractive to potential buyers. Robbins confirmed he is in the process of lining up a buyer for the site, but declined to comment on the developer.