Editor’s Note: This version corrects the approval process for a future application.

East Lyme — The Inland Wetlands Agency approved a permit Monday for the construction of a Costco at the Gateway Commons site near Interstate 95.

The agency's approval is the first step as the developers seek permits from the town to install the big-box store for the retail phase of the commercial and residential development.

An application from Gateway Development and Costco Wholesale Corp. would next proceed to the Zoning Commission.

The developers are proposing to build an approximately 138,000-square-foot Costco building, along with a gas station, parking area and access drives, according to their application.

They intend to develop roughly 12.5 acres of a 14.7-acre site on Flanders Road.

The application includes an operations and maintenance plan for the gas station and a storm sewer system with two stormwater management basins.

Most of the site currently drains to the Pattagansett River, according to a project summary prepared by the project engineer. 

Another portion, on the northeast side, drains to a wetlands system along I-95, which takes water under the highway through a culvert, according to the document.

In response to questions from the commission on Monday, soil scientists for the developers and a representative for Costco outlined the infrastructure to collect stormwater and the monitoring system for the tanks.

The commission listed conditions on the permit that the developers must comply with, including that the hydrodynamic separator be inspected every six months and that a copy of each inspection report for the stormwater basins be supplied to the town.

Silt fences and other erosion-control measures shall be inspected by the town's engineer and Inland Wetlands agent before construction begins, among other measures.

The permit also includes an erosion and sedimentation control bond and a bond for landscaping.

k.drelich@theday.com