By Shereen Siewert

The Wisconsin Department of Natural Resources is investigating the Wausau’s sewer collection system at an area along the Thomas Street corridor after city officials discovered the presence of a highly toxic carcinogen.

According to city documents, Wausau Water Works on Jan. 8 conducted “grab” samples at sewer mains at several points to have a better understanding of the Pentachlorophenol levels coming in to the city’s wastewater plant.  The grab samples were obtained by lowering a container mounted on a pole into the wastewater stream and scooping up a sample of wastewater, according to city documents. A Jan. 21 report shows the presence of Pentachlorophenol, or Penta, in four of six manholes dotting the neighborhood where residents have repeatedly expressed concerns over potential toxicity of the soil and groundwater.

On Feb. 15, Wausau Water Works Wastewater Superintendent Dave Erickson said the test results were submitted to the DNR for further review.

That discovery prompted the DNR to direct TRC, the consultants for Wauleco, to prepare a scope of service for further investigation of the collection system downstream of the Wauleco discharge point, which lies along the Thomas Street corridor and is part of a brownfield cleanup site. Matt Thompson, a hydrogeologist with the DNR, tells Wausau Pilot and Review the directive was given in a phone call.

A review of public records revealed that the city began allowing Wauleco to discharge its wastewater into the sanitary sewer system, which extends through Riverside Park and along the Wisconsin River before reaching the city’s wastewater treatment plant. City officials in 1991 requested a specific insurance policy from Sentry Insurance, Wauleco’s parent company, for doing so, according to city documents.

January’s test results are not the first instance of Penta contamination in manhole samples. In the mid-1990s, Wauleco collaborated with city officials to resolve contamination by installing seals in “wet zones” at sewer joint. It is not yet known if current Penta Wauleco contamination in neighborhood manholes stems from a similar problem.

Once a scope of work is defined, additional testing is expected to take place to verify the initial results, according to city documents.

Wauleco is also being asked to submit information about past burning practices at the property, which for decades was the site of wood manufacturing facilities. That request, dated Jan. 15, gave Wauleco two months to respond.

Penta, a highly toxic carcinogen, was once one of the most widely used biocides in the U.S. but it is now a restricted use pesticide and is no longer available to the general public. The chemical was regularly used for decades in wood treatment processes at former manufacturing facilities where a major road reconstruction project is planned to launch this spring.