Project Location: Central Illinois
Project Fees: $240,000
Over 250,000 gallons of toxic run-off from firefighting operations at an agricultural chemical warehouse fire threatened water supplies for humans and livestock. Two drinking water valve stations containing contaminated run-off posed a potential direct cross - connection problem. The valve pits were immediately pumped off and water supplies were monitored for contamination. One mile of an adjacent creek was contaminated with pesticide runoff. A network of interceptor and containment structures was installed to restrict the spread of contamination. Residues at the burn site posed a chronic soil and water contamination threat.
The presence of numerous known and unknown complex organics required the pragmatic selection of physical/chemical and biological indicator decontamination levels. Six pesticides were selected as indicator chemicals based upon their high aqueous solubility's and aquatic and mammalian toxicities. Gas chromatography was used to track these six pesticides. Aquatic bioassays were performed to determine the presence of any unknown contaminants and to monitor detoxification progress. Five waste streams were identified and several detoxification alternatives were considered.
Detoxification selection criteria was based on bench scale pilot-tests showing the best treatment efficiencies and cost effectiveness. The five waste streams identified were:
1. contaminated stream waters,
2. concentrated leachates at burn site,
3. contaminated soil residues,
4. contaminated building materials, and
5. contaminated product residues.
Leachate Transfer from Stream into Carbon & Bentonite 300,000 Gallon Treatment Cell
Contaminated stream waters were isolated and pumped into a 300,000-gallon polyethylene-lined treatment cell. Bentonite and activated carbon were added at the pumping station inlet to eliminate odors. Pesticide degradation was achieved via solar oxidation, aeration, evaporation, and sorption. Powdered activated carbon was injected into the lagoon at a self-flocculating concentration of 1,000 ppm. A carbon contact period of four hours, followed by a 48-hour clarification period, was employed. The treated contents of the lagoon were then pumped behind a sandbag carbon/bentonite impoundment. The treated water was released after laboratory analysis and bioassays confirmed that all indicator chemical concentrations had been reduced below established decontamination levels.
The concentrated leachates at the burn site were removed for disposal. To lower disposal costs, uncontaminated building materials were segregated for disposal at a conventional sanitary landfill.
Contaminated product, soil residues, building materials, and leachates were drummed and shipped to an EPA approved hazardous waste disposal site. Soils containing traces of agricultural chemicals at the burn site were treated with activated carbon for odor control and soda ash for alkaline hydrolysis half-life reduction. This procedure was repeated several times to accelerate the destruction of the pesticide residues.
Five - hundred gallons of product were recovered in original containers. These materials were disposed of at a hazardous waste disposal facility to alleviate potential third-party liability problems.