O6 ENV was contracted by Cedar Falls Utilities to provide project management, field resources, equipment and transportation and disposal of approximately 3,500 cubic yards of soil impacted with coal tar that was identified during construction activities at the plant. The source of the coal tar contamination was discovered to have originated from the gas holder tanks that remained in place from the former manufactured gas plant that operated on the site.
The impacted soil was excavated with an 80,000 lb. hydraulic excavator and loaded into end dump trailers and transported to Belleville, Michigan for disposal at a Sub-Title C Landfill. Source Material (Coal Tar) that was encountered and deemed not suitable for direct load was mixed with other non-impacted soil in order to pass paint filter and be suitable for transportation. The coal tar impacted soil manifested as Non-RCRA Regulated Waste under 40 CFR Section 262.34(a) which provides a RCRA Exemption for certain wastes generated from former manufactured gas plant activities.
The backfill utilized was from an on-site site borrow source. The borrow material was transported by tandem truck and placed with an excavator and compacted to the levels recommended in the scope of work.