The Department of Ecology is now considering options to clean up the site of a former cement manufacturing plant near the shore of the Spokane River that is still contaminated decades after production ceased in 1967.
Holcim Inc. owns the site, located in Spokane Valley across the river from Plantes Ferry Park. Tests show that neighboring parcels owned by the city of Spokane Valley and Neighborhood Inc. are also contaminated.
The primary contaminant is arsenic, but there is also gasoline, benzene and a few areas with higher than normal amounts of lead. The contaminants come from cement kiln dust stockpiled on the property, piled as deep as 25 feet in some areas.
The city’s land has a much smaller pile of kiln dust that isn’t as deep, but some of it comes into contact with groundwater during high-water periods, Jeremy Schmidt of the Department of Ecology said at an informational meeting Thursday evening. The arsenic on Neighborhood Inc.’s property is scattered and mixed in with the dirt and there are no large piles of kiln dust. The site was graded as part of the Coyote Rock development several years ago.
Two of 10 groundwater monitoring wells in the area have shown arsenic contamination during the past two years, but levels have been dropping for an unknown reason, Schmidt said.
One of the two contaminated wells is on Neighborhood Inc. land. “We might be at the end of the line where it rinsed out over the last 80 years, or it might be that we’ve had a couple of low-water years,” he said.
It’s important to note that an Irvin Water District well located south of the Holcim property has been repeatedly tested and no contamination has ever been detected, Schmidt said.
Cleanup options range from capping all three sites, capping one or two of the sites and removing contaminated areas from the others, or removing contaminated areas from all three sites. Cost estimates range from $1.6 million to $11.2 million.
Schmidt said Holcim prefers the alternative that would clean up land owned by the city and Neighborhood Inc., move the kiln dust and contaminated soil to the already contaminated Holcim land and cap it. The estimated cost is $2 million.
The city of Spokane Valley inherited its parcel from Spokane County when the city incorporated in 2003, said City Attorney Cary Driskell.
“Our understanding is that Holcim is paying for the entire remediation,” he said. “They have stood up for what occurred and are certainly being responsible.”