DEC addresses South Hill toxins

The difficult geology on Ithaca's South Hill makes it virtually impossible to actually remove toxic contamination from beneath neighborhoods, according to staff from the state Department of Environmental Conservation.

The DEC hosted a public meeting Thursday night at Ithaca Town Hall, attended by roughly 25 people, to present and answer questions on the agency's Proposed Remedial Action Plan for the neighborhood north and downhill from Emerson Power Transmission.

Emerson's predecessor, Morse Chain, used trichloroethylene (TCE) and other industrial solvents to degrease metal parts, and those solvents leaked out of the factory's fire water reservoir and were dumped directly into the city sewer system.

The DEC long believed that contamination in the neighborhoods came from the reservoir and moved downward. But they now believe the contamination came from toxic vapors in the sewer system and are moving upward, said DEC Geologist Carl Cuipylo. TCE is considered a likely human carcinogen.

DEC Project Manager and engineer Karen Cahill said that unfortunately, there's really no source of contamination to dig out and remove because the contamination is in vapor, not soil or groundwater. The vapor seems to have moved along sewer lines and through bedrock fractures "the size of a hair," she said.

The DEC's proposed remedy is to replace 300 feet of sewer pipe on East Spencer Street, and in the same sewer trench to install a perforated piping system that would, it is hoped, attract toxic vapors, which could then be vented out in the air, she said. The proposed system may be the first of its kind used for compounds like TCE, though similar systems have been used successfully to remove methane, Cahill said.

Questions by South Hill residents focused on whether the DEC would do follow-up testing on mitigated homes, and on the venting system, to see whether it's actually working.

"What if your theory is wrong?" asked Alderwoman Jennifer Dotson, I-1st.

Cuipylo said follow-up testing had not been considered by the DEC, but would be a good idea.

Ithaca Toxics Targeting President Walter Hang said re-testing is crucial, especially because the DEC's first cleanup decision for Emerson -- pumping and treating contaminated water from the fire water reservoir -- turned out to be "totally ineffective."

"They never came back to verify that the plan was working," Hang said.

Copies of the DEC's plan are available in the Tompkins County Public Library. The DEC is accepting public comment on the plan until July 9. Send comments to Karen Cahill at 615 Erie Blvd. W., Syracuse, NY, 13204, or email kacahill@gw.dec.state.ny.us.