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TECHNOLOGY EVALUATION REPORT: SILICATE TECHNOLOGY CORPORATION - SOLIDIFICATION/STABILIZATION OF PCP AND INORGANIC CONTAMINANTS IN SOILS - SELMA, CA
Citation:
U.S. EPA. TECHNOLOGY EVALUATION REPORT: SILICATE TECHNOLOGY CORPORATION - SOLIDIFICATION/STABILIZATION OF PCP AND INORGANIC CONTAMINANTS IN SOILS - SELMA, CA. EPA/540/R-92/010 (NTIS 95-255709), 1992.
Impact/Purpose:
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Description:
This Technolgy Evaluation Report evaluates the solidification/stabilization process of Silicate Technology Corporation (STC) for the on-site treatment of contaminated soil The STC immobilization technology uses a proprietary product (FMS Silicate) to chemically stabilize and microencapsulate organic and inorganic wastes, and to physically solidify contaminated soils. The STC demonstration was conducted under EPA's Superfund Innovative Technology Evaluation (SITE) Program in November, 1990, at the Selma Pressure Treating (SPT) wood preserving site in Selma, California. The SPT site was contaminated with both organics, predominantly pentachlorophenol (PCP), and inorganics, mainly arsenic, chromium, and copper. Extensive sampling and analyses were performed on the waste both before and after treatment to compare physical, chemical, and leaching characteristics of raw and treated wastes. STC's contaminated soil treatment process was evaluated based on contaminant mobility measured bv numerous leaching tests; and structural integrity of the solidified material, measured by physical, engineering, and morphological examinations. This report provides a comprehensive description of the SITE demonstration and its results including a description of data collection activities, testing procedures, and quality assurance and quality control (QA/QC) results. Conclusions resulting from this SITE demonstration evaluation are that: (1) the STC process chemically stabilized contaminated soils containing both inorganic and semivolatile organic contaminants; (2) PCP concentraions were reduced by 91 to 97 Percent as determined by total waste analysis (SW-846, Method 8270); (3).arsenic and copper were immobilized based on various leach-test criteria (4) chromium concentrations were very low prior to and after treatment, but showed slight to moderate increase in leachability after treatment; (5) PCP concentrations remained above California state regulatory threshold levels after treatment; and metal concentrations in the treated waste were not consistently below California state regulatory thresholds; (6) the short-term physical stability of the treated waste was good, with unconfined compressive strengths well above landfill solidification standards; (7) due to the addition of reagents, treatment resulted in a volume increase of 59 to 75 percent (68 percent average) and a slight bulk density increase; (8) six-month monitoring showed increased concentrations of the contaminants released from the treated waste; (9) eighteen-month monitoring showed improved percent reductions for arsenic and PCP relative to 6-month cured sample test results; (10) thirty-two-month monitoring showed comparable percent reductions for PCP relative to 18-month results, but arsenic leachability more closely resembled 6-month results; (11) chromium and copper showed slight to moderate increases in leachate concentrations over time although copper concentrations at 32 months more closely resembled 28-day results than either 6-month or 18-month results; and (12) unconfined compressive strengths increased an average of 145 and 245 percent for 32-month and 18-month samples, respectively, relative to 28-day values.