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ENVIRONMENTAL CONSTRUCTION AND REMEDIATION Jet Grouting A chemical manufacturing plant in upstate New York had spilled cadmium and heavy metals from the Onsite Wastewater Treatment Plant. A facility wide remedial investigation was conducted under the purview of a consent order with the New York DEC. The Owner, the State, Woodward-Clyde and Geo-Con agreed to work in concert under a Design/Build contract to remediate this site.
Cadmium was found up to 38 ft deep in sands and gravels beneath the old Wastewater Plant, which was located in a narrow, blind alley in the plant. Excavation in the alley was too difficult and costly, so stabilization of the cadmium using jet grouting was selected as the remediation method. A treatability study was completed which showed that cement was effective in stabilizing the leaching potential of the cadmium-contaminated soils.
Woodward-Clyde and Geo-Con produced the necessary design, health and safety and quality control plans and made submittals to the State, within 3 weeks of Owner approval. The State cooperated with an expedited review of the submittals so that construction could be completed prior to winter weather.
Construction began with the demolition of the heavy foundations from the old Wastewater Treatment Plant. A grout plant was setup at a location remote from the site, due to limited space in the alley. Buried underground utilities were identified and jet grout columns were installed to ready the site for production grouting.
Grouting was performed at 6,000 psi to create soil-cement columns with a diameter of least 42 inches. Over 500 columns were installed and overlapped to treat over 4,000 cy of soil. Considerable effort was used to protect the underground utilities, which were encased in the soil-cement. Excess grout and treated soils from other areas on the site were blended and used to create an extended slope on the site and eliminate off site disposal.
The project was completed on schedule and under budget. The State approved the remediation within 60 days of the completion of the work.
The goal of remediation, which was accomplished, treated soils so that the TCLP criterion of 1 ppm for cadmium was met.
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