Explanation of Significant Difference (ESD) for the A-Area Burning/Rubble Pits (731-A/1A) and Rubble Pit (731-2A) (U)

The A-Area Burning/Rubble Pits (731-A/1A) and Rubble Pit (731-2A) (ABRP) operable unit (OU) is located in the northwest portion of Savannah River Site (SRS), approximately 2.4 kilometers (1.5 miles) south of the A/M Area operations. Between 1951 and 1973, Pits 731-A and 731-1A were used to burn paper, plastics, wood, rubber, rags, cardboard, oil, degreasers, and solvents. Combustible materials were burned monthly. After burning was discontinued in 1973, Pits 731-A and 731-1A were also converted to rubble pits and used to dispose of concrete rubble, bricks, tile, asphalt, plastics, metal, wood products, and rubber until about 1978. When the pits were filled to capacity, there were covered with compacted clay-rich native soils and vegetation was established. Pit 731-2A was only used as a rubble pit until 1983 after which the area was backfilled and seeded. Two other potential source areas within the OU were investigated and found to be clean. The water table aquifer (M-Area aquifer) was also investigated