ST. PAUL — The Minnesota Pollution Control Agency is asking Ford Motor Co. to examine a dump site at its former St. Paul plant this month to make sure it is free of troublesome contamination.

If anything is found to be a risk at the site, Ford will have to clean it up before the state agency will approve the land for sale for redevelopment.

Ford “really wants closure from the MPCA and they understand there’s a process to get there,” said Amy Hadiaris, a hydrogeologist who works for the state agency’s voluntary cleanup program.

Officials with Ford Land in Dearborn, Mich., said the company is voluntarily working with the state agency to investigate and clean up the site. Ford says tests so far show that groundwater and the river have not been impacted.

But members of the Friends of the Mississippi River are concerned. The group wants Ford to sift the entire mound, which sits 65 feet above the river and covers about 4 acres, for industrial waste, and to determine the feasibility and cost of removing the dump and returning the site to its original state.

Friends’ executive director Whitney Clark said he fears the site may contain more chlorinated solvents, which can pollute groundwater, than tests have shown. He’d like to see more wells drilled — some deep into the aquifer.

“The MPCA needs to be requiring a higher level of due diligence on this site,” he said.

Hadiaris said chlorinated solvents haven’t been found in the dump or in four drums on the site. Ford typically used paint solvents that were petroleum-based, which flush through groundwater aquifers.

She said Ford agreed to determine the degree to which groundwater has been contaminated and how far industrial waste extends throughout the dump. Both shallow and deep wells will be drilled, she said.

The dump between Mississippi River Boulevard and the river north of Hidden Falls Park was used by Ford from about 1945 to 1966. Since then, debris was left there by the U.S. Army Corps of Engineers from its reconstruction of the nearby lock and dam, and by a St. Paul contractor working on a paving project.

Groundwater monitoring wells were installed in the 1980s. Testing found no significant impact on groundwater. By 1993 the site was taken off federal and state priority cleanup lists.