BANGOR — Maine is again seeking money from the federal government to clean up decades-old hazardous pollution at oil storage facilities.

In a lawsuit filed Aug. 9 in U.S. District Court in Bangor, Attorney General Janet Mills estimates it could cost Maine more than $10.8 million to clean up decades-old pollution at former Portland-Bangor Waste Oil Co. sites in Casco and Ellsworth.

The lawsuit seeks $413,433 and claims Department of Defense military bases disposed waste at the sites, which stored it in tanks that state investigations show leaked contaminants such as lead into the ground, contaminating nearby groundwater.

In 2010, Maine reached a $14 million settlement with non-federal actors who disposed waste at the company’s Plymouth site, including paper companies and municipalities. And in 2007, the state started a bond program to help groups that disposed waste at the company’s four sites pay response costs.

The Maine Attorney General’s office said the 2010 settlement did not include the federal government, and that the lawsuit seeks a settlement to finish recovering costs.

A Department of Defense spokesman said the agency does not generally comment on pending litigation.

The lawsuit says the federal government has violated the 1980 federal law that lays out a legal blueprint for addressing hazardous material removal. The law also created the Superfund, which pays for the cleanup of sites contaminated by hazardous pollutants.

Maine’s lawsuit seeks attorney’s fees, cleanup costs and damages for natural resources loss and destruction.

In May, the state won a $110,655 settlement from the federal government after arguing in a lawsuit that the agency shirked its duty to clean up hazardous waste from a South Berwick naval shipyard disposal site and left remediation up to Maine.

The Department of Defense didn’t admit to any wrongdoing in the settlement.

Both the Casco and Ellsworth sites were once owned and operated by Portland-Bangor Waste Oil, which transferred, stored, processed and disposed of oil from 1969 to 1980.

State and federal regulators investigated the sites from the 1980s to the early 2000s and found hazardous substances in soil, sediment and groundwater, according to the lawsuit. Substances included levels of trichloroethylene, tetrachloroethylene, lead and PCBs above state guidelines.

In Ellsworth, state investigators found contaminants likely from the site in two private water supplies and a public water supply used by a vocational center. The Department of Environment Protection treated the water and later extended a public water line while the city restricted the use of private wells in the potentially impacted area.

Remediation efforts at both sites already have cost the state $5.8 million, the lawsuit claims.

The department has removed roughly 8,800 tons of contaminated soils from the sites. It also is monitoring a 25-acre plume of groundwater contamination spreading out from the Casco site.