PASCO -- A system performing the cleanup work on a portion of Pasco's toxic waste site is getting a $1 million upgrade this fall.
Work has already begun at the Pasco Sanitary Landfill, just east of city limits at Dietrich Road and Commercial Avenue, to add to a vacuum system that is removing contaminated air from the ground.
Cleanup on the 250-acre site began more than 15 years ago and is focused on a 50-acre former municipal landfill and five zones of about an acre each -- called A through E -- where industrial waste was dumped in the early 1970s.
Investigation in the 1990s revealed water and soil at the landfill had been contaminated with volatile organic compounds from waste dumped there -- including paint, resins and herbicide and pesticide manufacturing waste. But no one knows the volume of contaminants at the site.
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The landfill was listed in 1990 as a Superfund site, targeted by a federal program for toxic waste cleanup. The state Department of Ecology is leading the effort, but the bill is being paid by those considered liable for the contamination.
The soil vapor extraction system being upgraded removes contaminants in Zone A before they reach the ground water.
The system in Zone A, where about 35,000 drums of industrial waste were dumped, reaches 60 feet deep and uses a vacuum to suck up contaminated air so a nearby flare system can burn the contaminants.
Six wells used to extract contaminants will be added in Zone A at graduated depths, said Chuck Gruenenfelder, Ecology's site manager for the landfill. The wells will be added in areas that don't have drums and will be under a dirt cap system that covers the buried waste and keeps water from infiltrating and spreading the contamination.
The idea is to capture the contaminants closer to the source, Gruenenfelder said. The existing system is removing contaminants from the perimeter of the zone, while the upgraded one will remove them from within the zone.
The work also will add about 10 testing wells to monitor conditions underground, he said.
The first phase of the upgrade will be finished this year, said Barbara Smith, president of Seattle's Harris & Smith Public Affairs, which represents those considered liable for the cleanup. The upgrades to Zone A will cost about $1 million.
The 40 companies and groups considered liable for the landfill contamination -- including Boeing, PACCAR, Freightliner and Weyerhaeuser Co. -- have spent more than $20 million on cleanup so far.
An underground plume of contaminants stretches southwest from the cleanup site to A Street. The ground water plume has shrunk in the last 10 to 15 years.
The technology used to catch contaminants before they enter ground water has been successful, Smith said. However, the parties want to make sure they improve the use of that technology to be even more efficient in removing contamination.
"It's a good idea to improve what is already a good system," she said.
In addition to work at Zone A, the upgrades include a new cover for Zone B, a half-acre where about 5,000 drums of herbicides were dumped. The drums and some contaminated soil were removed in 2002, but some pollutants remain.
The new cap system will cover the interim cap. Soil will be added on top with layers of plastic, and paths for runoff to flow out of the site will be covered with more soil and vegetation, Gruenenfelder said.
The goal is to minimize the amount of water that infiltrates the contaminated ground, he said.
The potentially liable parties are interviewing contractors now, so the cost isn't determined, Smith said. The work should start in 2011.
The upgrades are part of Ecology's process to determine the final cleanup solution for the zones, Gruenenfelder said. The information gathered will help them make the decision.
The ultimate goal is to have a final cleanup plan to address the contamination at the site for human health and the environment, Smith said. And upgrading the extraction unit and adding a new cap will help get there.
"We are removing contaminants and working toward cleanup," she said.