WASILLA — The Matanuska-Susitna Borough's booming growth and minimal zoning left a legacy of dumpsites, mine pollution and dairy contamination.

Now $550,000 in EPA "brownfield" grants will start the process of identifying sites around Mat-Su that could be good candidates for cleanup and future development, borough officials say.

Another $200,000 from the agency will go toward cleaning up historic petroleum hydrocarbon contamination at the Tesoro-Olson Site/Alpina Auto Repair Shop site on Spenard Road in Anchorage. The site has been used as a gas station since 1964 and as an auto repair facility, car wash and detail shop, woodlot, and rental car business since the mid-1990s, according to an U.S. Environmental Protection Agency press release.

The Mat-Su funding will be spent in partnership with the cities of Palmer and Wasilla, the relatively urban centers of a sprawling borough bigger than West Virginia.

Mat-Su is the fastest-growing borough in Alaska, ballooning from just 7,500 people in 1970 to nearly 100,000 today, according to an application for the funding. Unemployment rates can measure up to 2.5 times the national average.

A preliminary survey suggests at least 900 commercial or industrial sites in the Valley have potential environmental concerns, the application says. That's holding the borough back even as residents struggle to recover from the Great Recession and officials try to build tourism.

Palmer suggested focusing on the old Matanuska Maid complex and a 20-acre parcel near the Matanuska River, according to borough planner Frankie Barker. The Mat Maid dairy block, established in 1935, formed the heart of the New Deal farm colony around which Palmer sprang up. The dairy functioned for more than 60 years. Contamination includes diesel fuel, pesticides and heavy metals. The riverside property was used as a community dump in the 1940s and '50s, with refuse reportedly bulldozed into the river, then mined down to bedrock for gravel, according to the borough's application.

Wasilla's priority is the old railroad depot in a gravel pit along the Parks Highway, and below Home Depot, where the city hopes to install a new transit facility.

Piles of historic coal mine tailings in Sutton and Chickaloon could also fall under the program, as could the old Talkeetna Library, where petroleum contamination has been linked to railroad operations.

The borough is just at the identification stage now, Barker said. "I'm not sure how far into prioritizing we'll get but we'll certainly identify and pick out a couple key ones for the cleanup," she said.

Going through this phase of the brownfields process allows communities to apply for individual cleanup grants through EPA.