Groundwater will be restored to purity and about 40 cubic yards of soil contaminated by herbicides and pesticides at Defense Depot Ogden are to be cleaned up in a Superfund project expected to cost $676,000.

A cleanup plan adopted recently for the contaminated drain area north of Building 23 includes treating groundwater with an aeration device to strip organic chemicals and pesticides from it. Treated water will be pumped back underground."We are also considering using a carbon absorption process to further clean the water if the air stripping does not totally remove the pesticides and organics," said Del Fredde, environmental protection coordinator at the depot.

Soil laced with toxic chemicals will be taken to a hazardous-waste incinerator, where it will be destroyed. Back at the depot, the excavation will be filled with clean soil.

Defense Depot Ogden is the largest of six depots in the Defense Department, covering 1,139 acres. The depot supplies equipment to American armed forces worldwide; besides shipping material, DDO workers also work on material on site.

The drain area is just one of several "operable units" at the depot that need to be cleaned, said Kent Gray, director of the Utah Bureau of Environmental Response and Remediation. The cleanup plan was recently approved by the military, the state and the federal Environmental Protection Agency.

Originally, cleansing this unit was expected to take three years. Gray now believes the estimate is conservative, so it may take a bit longer.

Groundwater will be cleared to the level that it meets federal drinking water standards, he said. "We'll continue as long as it is necessary," Gray added.

One of the most important aspects of the cleanup is that the groundwater is to be treated, he said. It will be "restored to a good, usable condition again."

Asked about the cause of the contamination, Gray said he did not know the precise reason - "just past practices of the depot out there."