Chemical Oxidation

RECON frequently uses chemical oxidation to solve soil and sludge contamination problems. Chemical oxidation converts hazardous contaminants to non-hazardous compounds. Typical oxidizing agents include hydrogen peroxide, chlorine dioxide, potassium permanganate, and sodium percarbonate.

RECON combines chemical oxidation with a variety of technologies to achieve the best solution for a project. Chemical agents can be mixed into the soil or sludge by:

• Surface Mixing
• Deep Soil Mixing
• Shallow Soil Mixing
• Jet Grouting

Each of these technologies is discussed in detail elsewhere on our web site.

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Case Studies UNION PACIFIC RAILROAD Pine Bluff, Arkansas Remedial Construction Services, L.P. (RECON) was contracted to remediate approximately 1,150 cubic yards of soil impacted with acrylic acid and butyl acrylate from the location of a former train derailment. The soil acrylic acid concentrations ranged from 2 mg/kg to 400 mg/kg and the soil butyl acrylate concentrations ranged from 2 mg/kg to 400 mg/kg. Groundwater concentrations were 170 mg/kg for acrylic acid and 22 mg/kg for butyl acrylate. The objective of the project was to reduce the acrylic acid and butyl acrylate levels to less than 2 mg/kg in the soil and groundwater. Excavation and Treatment The lateral extent of the contamination was assessed to be approximately 40 square feet with a maximum depth of 16 feet. Treatment of the soil consisted of applying hydrogen peroxide and water to enhance the mixture. To treat each cubic yard of soil 1.8 pounds of 30% peroxide was used. The soil was mixed with a long-stick excavator to ensure a completely homogeneous mass of treated soil. After the soil oxidized for 48 hours, soil and groundwater samples were collected and analyzed. The treated soil was compacted back into the excavation and the area seeded with a fast-growing grass to provide erosion control. An additional concern on the project was an active rail line approximately 50 feet from the excavation. To ensure ground stability, sheet piling extended along the excavation wall and to a depth of 30 feet. H-beams were strategically placed to support the sheet piling and to aid in excavation of the soil. The sheet piling was left in the ground after completion of treatment and backfilling operations.

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GOODYEAR TIRE & RUBBER COMPANY Cartersville, Georgia When soils in one area of Goodyear´s Cartersville facility were determined to have been contaminated with significant levels of formaldehyde, Terra Constructors, an acquisition of Remedial Construction Services, L.P. (RECON), was retained to perform soil remediation using insitu chemical oxidation. In this process, an oxidant slurry is delivered to the target soils using the Single Auger Mixing (SAM) process. As the oxidant is brought into contact with the formaldehyde, a chemical reaction takes place that breaks down the contaminant into carbon dioxide and water both harmless compounds. Single Auger Mixing Method The SAM technique utilizes a specially designed, hollow-stem mixing tool with carbide cutting teeth. The tool is advanced and rotated into the soil by means of a crane-mounted turntable. Concurrently, the reagent is pumped through ports in the mixing tool and blended with the in situ soil as the mixing tool is lowered and raised through the target zone. A grid treatment pattern designed to achieve overlapping "columns" ensures uniform mass treatment. Production Work For this project, a 60-ton crane supported the drilling platform, which was capable of producing as much as 100,000 foot-pounds of torque. Torque was transferred to the 6-foot-diameter mixing tool. The oxidant, an adduct of sodium percarbonate, was blended with water in a high shear mixer to produce a pumpable suspension. Treatment of the 500 cubic yards of contaminated soil successfully reduced formaldehyde concentrations from as high as 42,000 mg/kg to below the specified cleanup level of 100 mg/kg.

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