RICHLAND — Work could begin this summer to start building a cover over closed portions of private company US Ecology's waste disposal trenches at Hanford.
The Washington State Department of Ecology plans a public meeting at 7 p.m. Wednesdayto provide information about the plan and hear comments. It will be at the state office at 3100 Port of Benton Blvd., Richland.
US Ecology and its predecessors have been disposing of commercial waste since 1965 on 100 acres of land leased to the state of Washington and subleased to US Ecology.
During those 45 years, environmental regulations have changed significantly, said Larry Goldstein, contract manager for closure of the commercial low-level radioactive waste disposal site.
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For the first five years, chemical waste was accepted and certain encapsulated medical research waste with chemicals mixed with radioactive waste was accepted until 1985. Before 1980, waste could be disposed of in cardboard and fiberboard packaging. In 1987, wooden boxes were prohibited.
A study that will lead to a final decision on cleanup action is under way and a decision could be made by the end of the year.
But preliminary data shows that hexavalent chromium, trichloroethene, chloroform and arsenic are in ground water. Soil is contaminated with nitrate, nitrite, uranium, hexavalent chromium and methylene chloride. Vapors of other chemicals also have been detected in the soil.
The planned cap over most of the disposal trenches that already are filled is intended to prevent water from driving contamination deeper into the soil or to the ground water.
"It would reduce the future threat to human health and the environment," Goldstein said.
The design for the cover will not be final until the study now under way is completed.
But as an interim step the lower level of the cover is proposed to be built before final decisions are made to provide immediate protection.
The lower level would include layers of about five feet of sand and a plasticlike liner topped with more sand and soil. Material is available now to build it from excavation for an expansion of Hanford's massive landfill for the federal government's mixed low-level radioactive waste, the Environmental Restoration Disposal Facility.
The upper layer of the US Ecology cover would include silt loam and silt loam mixed with pea gravel that would be planted with vegetation.
The goal is to allow water to evaporate from the surface of the cover and also for vegetation to soak up moisture with its roots.
The cost of the cover would be paid for with disposal fees collected for a site closure fund from 1986 until the start of 1993. Current fees are collected for the perpetual care and maintenance of the site.
Waste comes from organizations such as universities, hospitals, biotech firms and electric utilities in western states.
Comments may be made at the meeting, e-mailed to firstname.lastname@example.org or mailed to Larry Goldstein, P.O. Box 47600, Lacey, Wash., 98504-7600. The deadline is May 12.
-- Annette Cary: 509-582-1533; email@example.com;