Independence takes on unique remediation job for Northeast Ohio Regional Sewer District

In April, Independence Excavating was awarded a contract by the Northeast Ohio Regional Sewer District (NEORSD) to remove approximately 15,000 cubic yards of digested sludge from the Southerly Waste Water Treatment Plant and then perform a complete demolition of the six 90' diameter digester tanks and control chamber. At first glance, it seems like a fairly normal demolition and site work contract, but throw in the fact that the sludge was previously contaminated with low level radioactive particles, and the job takes a whole new direction.

The story begins over thirty years ago when a local medical equipment manufacturer contaminated the sewers with Cobalt 60 from their facility. The contamination was discovered and traced back to the company and the operation was shut down. The impacted sewage ended up in the digesters at the sewer district’s Southerly Waste Water Treatment Plant. The digesters were taken offline and have been sitting idle for close to 30 years due to the contamination. The Cobalt 60 has a half-life of approximately 5 ½ years and a good deal of the material is already spent.

The Northeast Ohio Regional Sewer District is currently performing expansion and an upgrade of facilities at the Southerly Treatment Plant and needs to remove the sludge and the digesters to make way for a new incinerator facility. Our portion of the contract is to remove the sludge, scan it for any radioactive particles, perform grab sample tests and haul it to a municipal waste facility once it is cleared. The task is not easy since the sludge has to be dried, run across a belt at a uniform depth for scanning and then loaded into trucks for disposal. A very detailed plan had to be compiled by T.G. Adams & Associate, the Sewer District’s radiological consultant for approval by NEORSD and the Ohio Department of Health. The plan had to cover all aspects of the process from drying to removal and handling to cleaning and decontamination of equipment. Everything in the digesters, including all piping and concrete, will have to be scanned, tested and cleared prior to being removed or demolished.

Once we have removed the digesters, we will install wick drains and a surcharge to help consolidate the soils in that area in preparation for the new incinerator facility. We will also be installing sheeting test piles so the new foundations can be designed and eventually built. The new facility is to be constructed on the digester site and is expected to be a 100 million dollar construction project. Independence is pleased to be working with the Northeast Ohio Regional Sewer District on this unique project.