AUGUSTA — Maine environmental regulators are demanding a strategy to reduce traffic drawn by what would become the state’s third-largest shopping mall as a condition for a crucial building permit.

Developers of the proposed $60 million Mall at Augusta have six months to submit their traffic plan to the Department of Environmental Protection.

If the developer, Northeast Simon & Associates, gets a final green light from the state and from the Army Corps of Engineers, it plans to begin ground preparation this fall and start construction of the 800,000-square foot mall in the spring. A fall 1992 opening is projected.

The DEP is imposing 22 requirements relating to traffic and water quality that must be met if it is to grant final approval of a site location of development permit. The permit was conditionally approved Friday by DEP Commissioner Dean Marriott.

“The only way I can approve this is for developers to mitigate the traffic impact,” said Marriott. He said he expects the developers to work with the state Transportation Department, the city and Kennebec Valley Transit to devise a plan that would have to be approved by the DEP.

It would include provisions for car pooling, van pooling and shuttle service, particularly for the 3,000 employees expected to be hired at the mall just off Interstate 95 near the Augusta Civic Center.

Traffic plans are unusual, although not unheard of, in Maine.

Because the Augusta mall would be built on 3 or 4 acres of wetlands, the Army corps must also approve the project.

In an effort to mitigate environmental damage, the developers recently bought nearby wetlands covering 120 acres, with plans to preserve them indefinitely.