The Geiger (C & M Oil) Superfund Site is the first US Army Corps of Engineers managed soil remediation project which utilized the in-situ stabilization/solidification technique to remediate the soil. This project involved the remediation of approximately 23,000 cubic yards of contaminated soil. Contaminants of concern included chromium, lead, PCB’s, toluene, benzene, and other organic compounds. Clean-up criteria for the stabilized material was equal to the National Primary Drinking Water Regulations, when tested using the TCLP leachate extraction method. Chromium, lead, and toluene were the main contaminants of concern, with TCLP clean-up goals of 150, 15 and 1,000 parts per billion (ppb), respectively.
This National Priorities List (NPL) site is located near Charleston, SC and was an abandoned old waste oil facility that utilized unlined shallow trenches for the storage of waste oil. As part of an interim remedial action at the site, the trenches were filled and covered with native soil. The soil profile consists primarily of sands and silts, with groundwater located at a depth of 3 to 7 feet below the ground surface. The site is surrounded on two sides by ponds and wetlands.
Stabilization work was performed at this site using a two-pass injection process. The first pass involved the injection of a reagent solution to chemically fixate the metals within the contaminated soil. The second pass involved the injection of a cement based reagent to physically stabilize and solidify the contaminated soil into a soil-cement. These reagents were blended in-place using a 12 foot diameter mixing auger attached to a crane-mounted drill rig. Approximately 700 overlapping columns were utilized over the entire treatment area to stabilize the soil to a depth of 10 feet.
This paper summarizes the initial testing programs and the final production work at the site. Extensive testing was performed throughout all phases of the project. This testing was performed for the purpose of mix optimization, quality assurance, and verification testing. Specific parameters tested included: TCLP testing of organics, metals and PCBs, permeability testing, and unconfined compression strength.