A large power supplier undertook the site remediation of a 14-acre legacy property in Northern Illinois, formerly a manufactured gas plant from the late 19th century through 1947. Above ground structures were demolished and removed. The site had a variety of contaminants in the soil and groundwater. The remedial action plan required excavation of contaminated soil for offsite disposal. Excavation depths required lowering the water table below the lowest excavation points. Site investigation and characterization activities projected dewatering flows up-to 1,000 gpm for contaminated groundwater that would need to be treated prior to discharge.
Clear Creek provided a treatment and filtration system for groundwater pumped from a well point dewatering system and excavation sumps. Water was directed into a series of weir storage tanks as a primary clarifying step in retaining gross solids and sediment. An ORP sensor and controlled in-line chemical injection were used to catalyze oxidation of the metals components in the raw water. Primary-treated raw water was directed to clarifier trailers, which incorporated micro-sand, polymers and coagulants to further clarify the water. Clarified effluent was then pumped through a bag filtration, hydrocarbon removal, and anionic exchange systems. Throughout the project, over 76 million gallons of contaminated groundwater was treated and discharged directly into a local waterway in full compliance with the NPDES permit requirements for the site. Clear Creek installed and operated the system 24 hours a day.