Overview of SWMU 6 Sampling Program

Soil Sampling Program - Objectives
The specific objectives of soil sampling and reporting at SWMU 6 were (1) to collect and chemically analyze composite and discrete subsurface soil samples from overburden soils; (2) to perform an evaluation of the data
with respect to RCRA hazardous waste characteristics; and (3) to provide data that can be used to evaluate residual risk through comparison to USEPA Region III Residential and Industrial RBCs and background concentrations.

Soil Sampling Program - Methods
To achieve these objectives, twelve soil borings were advanced. One representative composite sample was collected from the overburden soil, and one representative discrete sample was collected of the soils at depth from each of the twelve soil borings. The composite overburden samples were analyzed for full Toxicity Characteristic Leaching Procedure (TCLP) compounds including TCLP Metals, TCLP Volatile Organic Compounds (VOCs), TCLP Semi-volatile Organic Compounds (SVOCs), TCLP Pesticides, and TCLP Herbicides, plus corrosivity, ignitability, and paint filter liquids in accordance with SW-846 Test Methods. Results were compared to 40 Code of Federal Regulations (CFR) 261 Subpart C to assess the appropriate disposal methods for soil excavated as part of the PBS project. Reactivity was analyzed using the site laboratory methods for energetic material. RFAAP considers soils with less than 10 percent energetic material to be non-hazardous.

Discrete samples were collected from below the planned excavation depth of 25 feet below ground surface (bgs), or at probe refusal (if less than 25 feet bgs). Each of the twelve discrete samples was analyzed for
Target Compound List (TCL) VOCs, TCL SVOCs, TCL Pesticides/ Aroclors, Target Analyte List (TAL) Metals, and Explosives following SW-846 Test Methods. Soil analytical results were compared to USEPA Region III Residential and Industrial RBC Tables (hazard quotient adjusted to 0.1 for non-carcinogens) to evaluate the residual risk of compounds detected in the discrete samples. Although, exposure at depths of 25
feet bgs is not anticipated and the area is not likely to be developed residentially, the Residential RBCs were used as the initial screening levels.