Cleaning up sediment from a 1-million-gallon oil spill near New Orleans and disposing of assorted debris across Louisiana and Mississippi make up some of the largest environmental challenges remaining in the wake of hurricanes Katrina and Rita, environmental officials said during an Oct. 10 briefing.

About 1,700 homes and many public areas have been contaminated in St. Bernard Parish, La., following a Sept. 4 oil spill at the Meraux Refinery of Murphy Oil USA Inc.

Some of the homes have only light contamination, but those closest to the plant are considered heavily contaminated. It remains to be seen whether some of the homes and properties can be inhabitable again, Environmental Protection Agency officials said.

They said they expect Murphy Oil to be responsible for the cleanup and restitution.

While Murphy Oil is taking the lead, the EPA is independently verifying the results for about 10 percent of the samples collected by the company. Murphy Oil has so far has collected about 1,500 sediment samples from 841 residences.

Several samples showed levels of polynuclear aromatic hydrocarbons, diesel and oil range organic chemicals, and arsenic at levels exceeding the amounts environmental officials consider protective for adults and children over a long-term basis.

The U.S. Environmental Protection Agency and Louisiana officials are recommending that residents returning to the area avoid contact with oil sediment, wear protective clothing, and thoroughly wash if they come in contact with any sediment. They also recommend that those with children and pets stay away from the area.

In terms of storm debris, cleanup may take several months yet. "The sheer volume is still staggering," EPA Administrator Stephen L. Johnson said.