Only a few months ago there was a sediment lagoon at a large manufacturing plant in Grand Rapids, Michigan littered with a variety of contaminants. Nowadays, the pond is clean thanks to a group of innovative thinkers.

ORIN Remediation Technologies (ORIN), an environmental contractor out of Madison, Wisconsin, was approached by Environmental Quality of Detroit, Michigan to develop a solution to treat the contaminated lagoon sediments. The contaminant levels in the lagoon were approximately 6,000 ppm and consisted of chlorinated solvents (major constituents where 1,1,1- Trichlorethane, Tetrachloroethane, and Methylene Chloride) and low level PCB's. It was initially proposed, after analyzing the levels of the contaminants and calculating the volume of soil affected, that thermo desorption would be the most viable solution. Other solutions were investigated and ORIN was contracted to evaluate chemical oxidation as an alternative treatment approach.

The primary objective was to reduce the levels of chlorinated compounds to meet the waste disposal facility requirements, and in some cases, to meet the Toxicity Characteristic Leaching Procedure (TCLP) criteria. Although PCB's were present, the objective was to reduce the levels of chlorinated compounds only.

Various chemical oxidation treatments were tested with the most successful treatment being catalyzed persulfate. Catalyzed persulfate is a combination of peroxy compounds, acid solution and a metal catalyst. The catalyzed persulfate chemistry was designed for the oxidation of a wide range of contaminants such as chlorinated solvents (including ethanes) and aromatic hydrocarbons. Bench level testing showed catalyzed persulfate reduced the total chlorinated compound concentration from 6,052 ppm in soil to 122 ppm, a 98% reduction..

Catalyzed persulfate was applied to the contaminated soil via hand held nozzles, pump at a rate of 5 to 10 gallons per minute and mixed into the soil with an excavator until saturated. Soils were treated in 4-foot lifts and approximately 500 cubic yards of soil were treated per day. Evidence of oxidant influence was visually observed during the application. After mixing in the treatment chemical, the soil was allowed to react with the catalyzed persulfate for approximately 24-hours. Afterwards, samples were collected and analyzed to determine if the treatment reduced the levels below the disposal criteria. In highly contaminated areas, two or three treatments were required to effectively treat the contaminants.

ORIN successfully remediated approximately 4200 cubic yards of contaminated soils that were shipped off-site. To treat the 4200 cubic yards of soil, ORIN applied 469,727 pounds of chemical and water. Cleanup and coordination of the project took about six months from initial studies to final treatment and disposal.

The cost of the chemical oxidation process was under $750,000, including the treatability study and full-scale treatment. By way of comparison, the projected cost of thermo desorption for the whole site was estimated in excess of $3,000,000, thus saving the client over $2,000,000.

Phone: 608-838-6699
Fax: 608-838-6695
E-mail: lkinsman@orinrt.com
Web: www.orinrt.com
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