Phosphate-induced metal stabilization (PIMS™) using Apatite II™
-- Apatite II™ uses a natural, benign material derived from processing fishbone waste products to treat soil contaminated with heavy metals.
-- In August 2002, a full scale application was conducted by treating 3,000 cubic yards of lead (Pb)-contaminated firing range soil at Solid Waste Management Unit (SWMU) B-20 at the CSSA. Apatite II™ binds Pb into Pb-pyromorphite, an insoluble phase that is stable. Pb-pyromorphite has an extremely low solubility and will remain insoluble under most environmental conditions.
-- Approximately 3% by weight of Apatite II™ material was mixed with Pb-contaminated soil at a rate of about 500 yd3 per day.
-- Soil, groundwater and leachate samples were collected for chemical analysis.
Demonstration conducted under the Department of Defense (DoD) Environmental Security Technology Certification Program (ESTCP).
Dr. Judith Wright
UFA Ventures, Inc.
403 West Riverside Dr.
Carlsbad, NM 88220
Dr. James Conca
Carlsbad Environmental Monitoring & Research Center
Carlsbad, NM 88220
1408 Moore Place, SW
Leesburg, VA 20175
8000 Centre Park, Suite 200
Austin, TX 78754
Pb-containing bullets used at the firing range
Type/Quantity of Media Treated:
Soil (3,000 cubic yards)
Purpose/Significance of Application:
The purpose of the full scale application was to determine suitable emplacement methodologies for the treatment of Pb-contaminated soils using PIMS™ and to determine actual field implementation costs.
Regulatory Requirements/Cleanup Goals:
Three cleanup goals were established for the site:
-- Cleanup goal for leachate from amended soils - Maximum contaminant level (MCL) for Pb in drinking water (0.015 milligrams per liter [mg/L])
-- The State of Texas class 2 nonhazardous waste classification criterion for Pb (1.5 mg/L for soil) in leachate using the Toxicity Characteristic Leaching Procedure (TCLP)
-- Reduce the bioavailability or bioaccessibility of the Pb in the soil
The untreated soil contained an average total Pb concentration of 1,942 mg/kg and did not meet State of Texas class 2 nonhazardous waste classification criterion of 1.5 mg/L Pb in leachate. After treatment with PIMS™, the treated soils met the TCLP criterion with an average TCLP Pb concentration of 0.46 mg/L. Analytical results of the field leachate from the site after treatment indicted an average of 0.0065 mg/L Pb concentration, well below the 0.0150 mg/L EPA standard for Pb in drinking water. Bioaccessibility data showed that treatment reduced the bioavailability of lead. A U.S. patent (#6,217,775) was awarded for PIMS using Apatite II™ during the course of this application.
The total costs for this demonstration was $63,775 which includes $8,100 in start-up costs and $55,675 in operational costs.
Lead-contaminated soils at Department of Defense (DoD) range sites are widespread. These soils pose one of the costliest environmental issues facing the DoD. CSSA was chosen as the test site because it is representative of many other DoD sites, both in contaminant type and field characteristics.
The PIMS™ technology is an in situ stabilization or sequestration technology that uses a natural, benign material, Apatite II™. During treatment, Apatite II™ is mixed into the contaminated soil using nonspecialized equipment such as a front-end loader and a maintainer. The Apatite II™ causes the Pb to form Pb-pyromorphite, which immobilizes the Pb without changing the basic nature of the soil. This technology allows the soil to be reused or disposed as a nonhazardous material.