East Lyme — The Zoning Commission, satisfied that safeguards in place will protect the town's aquifer, has approved plans for a big-box Costco store, with a gas station, as the "anchor store" for Gateway Commons near Interstate 95.

The commission voted 5-1 Thursday to approve the Costco plans, which call for a 138,000-square-foot building, 644 parking spaces and an eight-pump gas station, with no diesel fuel, on a 14.7-acre parcel on Flanders Road.

The Costco project is part of a commercial and residential development on the south side of I-95 near exits 74 and 73 that Simon Konover of West Hartford and KGI Properties of Providence have been planning for about a decade.

During Thursday's meeting, the commission asked questions about the exact distance between the proposed gas station and the town's mapped aquifer protection zone and what safeguards would be in place, given the proximity to the protection zone.

Michelle Carlson of BL Companies in Meriden said the site's three 30,000-gallon underground tanks, which would be about 300 feet from the town's aquifer protection zone, would be double-walled with a monitoring system, and the piping would have three levels of protection.

She outlined a list of safety features for the gas station that she said are designed to meet or exceed federal standards for underground storage leak prevention and detection.

The site also will have three monitoring wells, at the request of the town.

The town had adopted updated aquifer protection zones in 2013, based on new state guidelines.

The Day reported that the proposed gas station, which would have fallen within the town's previously larger aquifer protection zone, is on top of the sandy soils of the aquifer but outside of the portion of the aquifer that directly supplies the town well.

On Thursday, Chairman Matthew Walker said that the location of the gas station was on many people's minds and was a "big consideration" for the public and the commission, but Thursday's presentation illustrated that it would be outside of the town's mapped, updated aquifer protection zone.

Walker said the system's safety features — such as alarms and surveillance — are impressive. 

Commission member Terence Donovan said that one of his concerns was the underground tanks, but he thought the double-walled tanks and the type of piping addressed those concerns.

Walker, William Dwyer, George McPherson, Donovan and Peter Lukas voted in favor, while John Manning was opposed.

Theodore Harris, an attorney for the developers, had said the Costco store will be the "catalyst" both for other retail stores in the commercial part of the development and for improvements to I-95.

The commission had approved in 2008 a Master Development Plan for Gateway Commons. Regulations for Gateway permit the developers to install up to 425,000 square feet of retail space, with an "anchor store" and up to five "junior anchor stores."

The commission approved last year an interim access road and interim on and off ramps for I-95 southbound's Exit 74 to allow the Costco to open.

John Mancini of BL Companies said that the developers are in the third and final stage in securing a certificate from the Office of the State Traffic Administration. He said one of the planned interim ramps terminates over one of the "non-access lines" for I-95, so they are working with the state, as well as the Federal Highway Administration, to get approval.

The process requires federal permits and environmental reviews, and he said "they are heading down a path of about six months of environmental reviews."

Once the developers have the approval, they will then reconvene with Costco to determine the best time of the year to open a business, so the exact date of opening is not yet known, he said.

He also said the state has met with town officials about plans to improve the entire interchange and replace the overpass.

k.drelich@theday.com