Technical change to the work plan for the remedial investigation of the Salmon Site, Lamar County, Mississippi: Sampling and analysis plan background soil and groundwater study

The Salmon Site, formerly known as the Tatum Dome Test Site, is located in south-central Mississippi, southwest of the city of Hattiesburg, in Lamar County. Between 1964 and 1970, two nuclear and two non-nuclear gas explosions were conducted deep underground in the Tatum Salt Dome beneath the site. The tests were performed as part of the former US Atomic Energy Commission`s Vela Uniform Program which was conducted to improve the United States` capability to detect underground nuclear explosions. This document details technical changes to the existing work plan for the remedial investigation of the Salmon Site. A previously conducted Remedial Investigation for the Salmon Site involved the preparation of ecological and human health risk assessments. These risk assessments, which are incorporated into the Remedial Investigation Report, identified several constituents of potential concern (COPC) that could potentially have a negative impact on ecological and human health. These COPC are the primary risk drivers for the Salmon Site; they include arsenic and naturally occurring, gamma-emitting radionuclides. If it can be demonstrated that similar concentrations of these COPCs occur naturally in surrounding areas, they can be removed from consideration in the risk assessments. The purpose of this sampling effort is to collect enough data to prove that the COPCs are naturally occurring and are not a result of the explosives testing activities conducted at the site. This will be accomplished by collecting enough soil samples to have a statistically valid population that can be used to produce defensible comparisons that prove the concentrations identified on site are the same as the background concentrations in surrounding areas