NIPSCO remediating St. Mary’s River
By Gwen Clayton | Greater Fort Wayne Business Weekly
Northern Indiana Public Service Co. has timed some environmental remediation work it just started on a Fort Wayne section of the St. Marys River to support the city’s riverfront redevelopment efforts.
The work undertaken in cooperation with the Indiana Department of Environmental Management’s Voluntary Remediation Program will clean up coal tar and other byproducts resulting from standard manufactured gas production processes used across the country for more than 100 years until the mid-1950s.
In Fort Wayne, a manufactured gas plant operated at the northwest corner of Superior and Lafayette streets between 1851 and 1948. Coal, coke and sometimes oil were heated in a closed vessel to make “town gas,” which was stored in large, round gas holders after it was cleaned of impurities. Dense, oily coal tar would condense out of the gas as it was made and distributed.
“No tests we have done say it has gotten into the ground water, but we’re remediating the property to make sure it never does,” said Dana Berkes, a NIPSCO spokeswoman.
Contractors removed coal tar during the 1990s from a former gas holder location at 320 E. Superior St., and from three underground structures at the 305 E. Superior St. location of the former gas plant, in the building that now houses the Hall’s Gas House restaurant.
Seepage over the decades of coal tar into some of the soil at the 305 E. Superior St. parking lot required its excavation for offsite disposal, which took place in 2009. The same year, similar soil was stabilized there and at a strip of land in Headwaters Park by mixing it with cement-based grout.
An interceptor trench was installed along the nearby river bank to keep any coal tar that could have been missed from seeping into the river.
For the remediation just starting, river channel access was closed Sept. 24-Dec. 24 so the top two feet of sediment could be dredged from a 400-foot stretch of the St. Marys near the old gas plant.
The intersection of Duck and Barr streets also is scheduled to close Oct. 1-Dec. 1 to accommodate the work. The city planned to post signs for a detour through an adjacent parking lot it owns in front of an ice-skating rink.
Contractors hired for the project will prepare the dredged material in a secured area of Fort Wayne’s Old Fort property, then move it to an approved landfill. The Old Fort will remain open while the work is underway, and the work will be halted for scheduled events at the local historic attraction.
Once the dredging is done, contractors will install over the related stretch of river bed a cap of clay along with a mat designed to capture and isolate any migrating material with tarry riverbank seepage. To protect it from river flow, the mat will be topped with gravel and rip-rap.
A decade’s worth of pilot testing has shown the mat’s isolation capabilities can reduce odors and water surface luster experienced occasionally on rivers, according to information NIPSCO has posted about the project at www.nipsco.com/fort-wayne-gas-plant.
Improvement of surrounding riverbanks and a combined-sewer outfall also will prevent migration of tarry seepage through the corridor as well as riverbank erosion.
The work is expected to take three to four months, but Berkes said the pace of the dredging could be slowed by water level fluctuations in the river.
“Whether NIPSCO did this project this year or next year doesn’t affect our workload too much, but we really moved this project to a priority place because it makes a lot more sense,” she said.
Riverfront development “is at a fantastic momentum point for Fort Wayne,” Berkes said. “Certainly, we’d never want to be holding back that project because we haven’t done river remediation yet. We want to get in and get out of the way as the city continues to push the riverfront to a peak.”