NIPSCO will start environmental remediation of the St. Marys River near a former manufactured gas plant located at the northwest corner of Superior and Lafayette streets, the company announced Friday.
The work will focus on the impact of manufacturing byproducts, mostly coal tar, which remains beneath the river. The top two feet of sediment will be dredged to isolate material that seeped from the riverbank on the west side.
Crews will also improve the city combined sewer and the surrounding riverbank to prevent any potential seepage. It’s expected to take three to four months to finish depending on the river levels.
The gas plant operated from 1851 to 1948. It was part of a common manufacturing process throughout the country in the early 1800s through the mid-1950s.
Gas was captured and cleaned of impurities before being stored in large structures. It was then distributed for lighting streets, homes and businesses.
NIPSCO contractors removed coal tar from the base of a gas holder and three underground structures at the plant in the 1990s.
In 2009, impacted soil was excavated from the 305 Superior Street parking lot for offsite disposal. Crews built a trench to prevent small amounts of coal tar along the St. Marys River. Cleanup options are under consideration for this area of the site.
Material that is pulled up will be put in a secure area at the Old Fort before it is moved offsite to an approved landfill. The Old Fort will stay open during the work.
The St. Marys Pathway will be marked with detours. Barr and Duck streets and the river channel access will be closed for a limited time. Closure signs will be posted for boat traffic and detour signs will be posted at Headwaters Park.