July 12, 2001

Studies sniff out Tacoma smelter plume

  • For Ecology, the biggest issue with the Tacoma smelter plume site is how to address widespread soil contamination in the most populated center of the state without unnecessarily triggering public alarm bells from University Place to Bellevue.
    Department of Ecology

    It has been more than a year since King County Executive Ron Sims announced that soil testing in forested, undisturbed areas throughout Vashon and Maury islands and in eight coastal parks in southwest King County revealed elevated levels of arsenic and lead above state cleanup standards.

    The most likely source of the contamination was Asarco’s copper smelting plant in Ruston, near Tacoma. From 1890 to 1986, emissions from the plant, which included arsenic, lead and other heavy metals, were probably carried by wind and deposited over Vashon and Maury islands as well as mainland King and Pierce counties.

    The widespread soil contamination left by the smelter is called the Tacoma Smelter plume site.

    The state cleanup standard for arsenic contamination in residential soils is 20 parts per million (ppm). The cleanup standard for lead in residential soils is 250 ppm.

    In relatively undisturbed areas on Vashon and Maury islands, the Department of Ecology and Public Health — Seattle & King County found one soil sample with an arsenic contamination level at 460 ppm. The highest single soil sample for lead was 1,100 ppm. Of the approximately 450 soil samples taken, many were above state cleanup standards but at levels lower than the extreme cases.

    For Ecology, the issue is how to address widespread soil contamination in the most populated center of the state without unnecessarily triggering public alarm bells from University Place to Bellevue.

    “You start by building partnerships — with other state and local agencies, city governments, home and property owners, residents, businesses — everyone who is affected by potential contamination,” said Ecology’s Marian Abbett, environmental engineer and project manager for the Tacoma Smelter plume site.

    Since Sims’ April 2000 press conference, Ecology has awarded a $1.7 million grant to Public Health — Seattle & King County to help address a myriad of contamination issues. For example, two health surveys were conducted to determine if residents on Vashon and Maury islands have experienced an increase in cancer and non-cancer health problems related to arsenic and lead.

    Health officials found no statistically significant increases in the number of cancer-related deaths but they did discover a higher-than-normal level of prostate cancer. The health department is working on the results of the non-cancer health study. Preliminary results indicate that the study may not be sensitive enough to detect non-cancer health effects.

    Since children are most at risk of being exposed to arsenic- and lead-contaminated soils, Ecology and the Seattle-King County health department have been working closely with a resident committee to identify and test child-use areas on Vashon and Maury islands.

    Last fall, soil samples were taken at 34 different island schools, daycare centers, campgrounds, parks and beaches to determine contamination concentrations. The sampling results, released in May, showed that while some child-use properties had average levels of arsenic and lead contamination above state cleanup standards, Ecology announced that none of the properties required immediate cleanup action.

    “None of the child-use properties had averaged levels of contamination that would cause us to require that immediate cleanup action be taken,” said Ecology’s Norm Peck, site manager for Tacoma Smelter plume activities in King County. “Although some properties had averaged levels of arsenic and lead a bit above the state cleanup standard, we felt most risks could be best addressed in the short-term by helping property owners put good, solid protection measures in place.”

    The protection measures include covering bare dirt in play areas, having everyone wash his hands when they come in from outside and avoid letting anyone eat or drink outdoors in a contaminated area.

    Peck said child-use properties with arsenic and lead contamination above the state standard will be addressed as part of the long-term cleanup plan for the entire plume site.

    One of the big questions about the Tacoma Smelter plume is just how large an area has been contaminated with arsenic and lead. This past winter, Ecology and local health officials began looking at the rest of King County to figure out the best way to determine how big the “footprint” of the plume may be.

    In February, the two agencies took soil samples at 60 different sites in mainland King County. To get the best baseline information, samples were collected at parks and other undisturbed areas in more than 12 different communities in King County, including Auburn, Bellevue, Burien, Des Moines, Federal Way, Kent, Mercer Island, Newcastle, Normandy Park, Renton, Seattle, SeaTac and Tukwila.

    The results should be completed in late summer.

    Ecology and Seattle-King Co. health staff have also been meeting with various city and community leaders in mainland King County to discuss the sampling program as well as help coordinate education and information needs for those communities.

    In March, Ecology released a report outlining the extent of arsenic soil contamination in Pierce County’s University Place. University Place was chosen as a starting point in the daunting task to look for arsenic and lead in residential soils in the whole of Pierce County and other neighboring counties.

    Ecology first learned of arsenic in University Place three years ago. Back in 1985, two water tanks in University Place had been sandblasted. In a routine inspection of the tanks, Tacoma’s water department discovered the sandblast grit (including lead paint chips) remained in the tank area and had also been carried into neighboring yards and a greenbelt when the tanks had flooded.

    In its investigation of the water-tank problem, the water department discovered arsenic and lead in places well beyond where the particles would have landed from the sandblasting. The data prompted utility officials to believe the contamination came from another source, and Ecology stepped in.

    Ecology and the Tacoma Water Department developed a strategy to assess whether there were elevated area-wide background concentrations of arsenic and lead throughout University Place. The resulting Tacoma Water Department study indicated that background conditions in undeveloped, wooded lands were indeed elevated.

    In 2000, soil samples were taken from 59 residential yards. The average arsenic concentration was 26.4 ppm, slightly above the 20-ppm cleanup standard. In 60 percent of the yards sampled, average arsenic concentrations were over 20 ppm. However, in 80 percent of the yards sampled, arsenic was below 40 ppm.

    Joyce Mercuri, Ecology site manager for Tacoma Smelter plume activities in Pierce County said the public announcement of the contamination is just the start of Ecology’s work in Pierce County. She said the most important message so far has been to tell people what they can do to protect themselves and their children.

    “We’ve gotten great assistance from the local health department to do this,” said Mercuri.

    While the levels of lead and arsenic contamination do not constitute an imminent public health threat, Marian Abbett said the agency is concerned about the public’s persistent exposure to low levels of arsenic and lead over a long period of time.

    “Normally, Ecology deals with cleaning up sites that are measured in feet, yards or even acres, but the Tacoma Smelter plume literally encompasses hundreds of square miles,” said Abbett. “This site is unprecedented in its scope and complexity. It will take years to properly address.”

    For more information about the health effects of arsenic and lead as well as to learn more about community protection measures check out the Web site at

    Ecology’s Web site is at

    Curt Hart is the public information officer for Ecology’s Activities in Northwestern Washington.

    Sandy Howard is the public information officer for Ecology’s Activities in Southwestern Washington.

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