Soil samples are used to establish background levels of radionuclides (both natural and those resulting from fallout from nuclear weapons-testing) and to detect any long-term buildup of radionuclides from the INL in offsite soils. Soil is taken from 12 offsite locations in even-numbered years. Each soil sample consists of a composite of five cylindrical cores of soil. One is taken at the center and four at the corners of a 1076-square foot square. Samples are taken at each of two depths, 0-2 inches and 2-4 inches, at each location. Sampling locations are undisturbed areas, as evidenced by the presence of mature native vegetation and sagebrush.

Soil is sampled at RWMC, Butte City, Birch Creek, Monteview, Rexburg, Mud Lake, FAA Tower, Aberdeen, Blackfoot, Atomic City, Carey, Arco, St. Anthony, and Howe.