CANON CITY, Colo. -- The managers of a uranium mill are asking state regulators to let them stop testing a leaking radioactive pond because conditions are too dangerous for workers.

Cotter Corp. managers said wooden pallets leading into the pond near Canon City have sunk into muck, and it's dangerous to keep measuring the acidity of the pool.

Cotter also notified department regulators that the company will also investigate a recently discovered plume of the industrial solvent trichloroethene after it was detected in groundwater at levels exceeding federal health limits.

The mill was built in 1958 with federal support to process uranium for weapons and power plants. Cotter dumped waste in 11 unlined ponds, leading to contamination of groundwater for local communities.

Travis Stills, an attorney opposing the use of pallets to access the ponds, said it was a "gross error."

Public health department officials said Wednesday they are still considering Cotter's request to suspend testing.

"It seems like a reasonable request," department radiation control unit manager Steve Tarlton told the Denver Post.

Tarlton also said Cotter's proposed approach to investigating TCE contamination is a good tactic, but he said further testing and remediation might be necessary.

Cotter is in the process of dismantling its uranium mill.

The company has been moving 90,000 gallons of radioactive sludge and solvents into the impoundment, even though regulators know it is leaking.

State health regulators believe underground clay barriers will keep new contamination in the impoundment and prevent TCE from reaching residents of Canon City.

Federal Environmental Protection Agency officials in 1984 declared the mill and surrounding area a Superfund environmental disaster, then asked state authorities to supervise the cleanup.