By Shereen Siewert

WAUSAU — The State Department of Health Services is recommending further testing for potential dioxin contamination in soils in Riverside Park and along the Thomas Street corridor, according to a letter sent Feb. 7 to city officials.

The letter, along with the results of a Phase I Environmental study completed this month on the Riverside Park property, are included in the public packet for Monday’s meeting.

Toxicologist Clara Jeong, who wrote the letter, will appear Monday at a public meeting to discuss the department’s findings after her department’s initial analysis was sharply criticized by a nationally recognized toxicologist who called the report “inadequate and incomplete.” Stephen Lester, a scientist formerly with the Environmental Protection Agency, blasted the state’s report for failing to take into consideration potential cancer risks associated with dioxin. Lester is now the director of the Center for Health, Environment and Justice.

In her letter, Jeong outlines new cancer hazard calculations for the park based on existing data and concluded that exposure to dioxin in surface soil at Riverside Park for occasional recreational park users  and for Thomas Street residents “does not cause an unacceptable increased risk of cancer.”

But Jeong cautioned, however, that the park report is based on a single set of samples taken 13 years ago from a culvert at the top of a steep hill in the park. Dioxin levels in other areas of the park have not been characterized, Jeong stated, and there is a possibility that tainted water from the culvert’s outfall could have migrated into the park by rolling downhill.

An appendix to the letter shows soil samples at the culvert inlet are between 17 and 26 times the EPA’s residential regional screening level.

Based on the limited amount of data, the state is recommending further assessment to fully understand the potential health impact in the community. Jeong specifically points to the location of the park, which is adjacent to a former wood treatment facility that used Penta, or PCP, for decades. Those products, Jeong pointed out, contain dioxin and impurities.

“Considering the amount and length of PCP use during the operation, it is important to assess the levels and extent of dioxin on-site as well as the potential of dioxin migration to off-site locations,” Jeong wrote.

Jeong did not explain in her letter why cancer risks were not included in the state’s initial report, which led city leaders to declare the park safe.

The Phase I Environmental Study, which was conducted by local engineering firm REI, points to several areas of concern. REI points out that the investigation of the nearby wood manufacturing site, a property now owned by Wauleco, is still ongoing and being monitored by the Wisconsin Department of Natural Resources.

“This site clearly has impacted groundwater which has migrated off the Wauleco site and onto adjacent properties including Riverside Park,” the assessment states.

Groundwater contamination would not be encountered by park-goers. But investigation for aerial deposition, something which could have had an impact in soils in Riverside Park, is still being scoped. The DNR has requested a scope of work to address the aerial deposition associated with the combustion of wastes generated at the facility by March 16.

That scope will identify additional sampling to be performed by Wauleco and will be under DNR review.

Based on the initial assessment, REI is also recommending additional investigation to better understand the health risks in the area.