Metal toxicity evaluation of Savannah River Plant saltstone comparison of EP and TCLP test results

Saltstone is the waste treatment and disposal concept for low-level defense waste at the Savannah River Plant. The waste is a sodium salt solution which has about 230 5Ci/L in addition to the hazardous characteristics of corrosivity (pH > 12.5) and metal toxicity (Cr+6 > 100 ppm). The design objectives for a wasteform to stabilize this solution include: 1) eliminating hazardous characteristics of the waste; and 2) minimizing the release of potential contaminants, such as NO3- and radionuclides, so that drinking water standards are maintained for groundwater at the perimeter of the disposal site. Two EPA test procedures are routinely used at SRP to evaluate metal toxicity of wastes and wasteforms. These tests are: 1) the Extraction Procedure (EP) and; 2) the Toxicity Characterization Leaching Procedure (TCLP). The EP test is required by SCDHEC and EPA. The TCLP is used to evaluate the effect of increased surface area on metal leaching from the various SRP wasteforms