Final Kunia cleanup proposed

By Jan TenBruggencate
Advertiser Science Writer

The Environmental Protection Agency is proposing a two-tiered method for the final cleanup of the former Del Monte chemical-mixing station in Kunia and the contaminated groundwater beneath it.

The EPA concluded that the presence of agricultural chemicals in the water poses an unacceptable cancer risk for residents. The agency's proposed cleanup methods would cost Del Monte nearly $13 million and could last until 2010 or 2011.

The chemicals, used to treat nematodes in pineapple fields, are ethylene dibromide or EDB, dibromochloropropane or DBCP, and dichloropropane or DCP. There is also tricholoropropane or TCP, a solvent. They got into the soil from a 495-gallon spill in 1977 and from smaller spills in a pesticide-mixing area during the same time.

The chemical-mixing plant was adjacent to the plantation's housing camp, Kunia Village, and tests in 1980 found chemicals in the drinking water provided from the Kunia Camp well. The well was shut down, and Kunia Camp's water was provided from a nearby uncontaminated source.

Del Monte tried aggressively pumping the Kunia Camp well to get the chemicals out of the ground and irrigated a field with the water. In 1981 and 1983, it also excavated 18,000 tons of soil from contaminated areas and spread it on a field. New wells were dug to pump contaminated water out of the ground from 1980 to 1994.

The EPA designated the area a federal Superfund cleanup site in 1994 and ordered tests to determine the exact extent of the contamination and to find ways to clean it up. It concluded there is no direct threat of exposure to Hawai'i residents at this time, but that there could be if the contamination is allowed to spread underground into areas where there are other potable wells.

"We have been working closely with the EPA on this, and our concerns are included in their plan," said Eric Sadoyama, environmental health specialist with the health department's Hazard Evaluation and Emergency Response Office.

"It is a good plan," said Calvin Oda, director of research for the pineapple company. "Del Monte Fresh stepped up to the plate. We have cooperated fully."

The proposed cleanup addresses two different bodies of underground water: perched water that is found from 20 to 100 feet below the surface, and basal groundwater about 830 feet down. Basal groundwater is the source of much of Hawai'i's drinking water.

For the perched area, the $3 million EPA cleanup plan has a combination of features. Perched water would be pumped out of the ground and spread over an area for a process called phytoremediation, in which the water would irrigate compost-enriched soil growing haole koa trees. The trees and microorganisms in the soil break down the toxic chemicals.

Contaminants in the shallow soil would be removed using a soil vapor extraction system, which uses a vacuum to suck air out of soil that might have contaminants in it. The resulting contaminated air would be treated with activated carbon filters. A cap of clean earth, covered with growing plants, would be placed on top of the contamination area. This treatment would continue for eight years.

For the basal water, a $9.9 million, three- to five-year process would include aggressive pumping of the aquifer to prevent the chemicals from traveling underground with the flowing basal water. Contaminated water would be treated with carbon filtration and air stripping, which is a process in which air is forced against a water cascade, causing volatile compounds to be transferred from the water to the air.

The EPA believes this method of treatment could bring the pumped water to a quality that meets drinking-water standards, but the treated water would be used for irrigation only.

The basal water treatment alternative would include establishing monitoring wells to determine whether the contamination level is dropping or the contamination is moving, and whether additional extraction and treatment wells are needed.

Reach Jan TenBruggencate at jant@honoluluadvertiser.com or (808) 245-3074.