At each mosasaur location, a representative of the S.D. School of Mines advised OE safety personnel on the area required for OE avoidance to preserve these ancient marine reptiles, and clear the way for additional environmental work at the site. During this recovery project, initial efforts of OE avoidance involved providing safe access for site workers to travel from the entrance to Burning Ground 2 to the mosasaur locations, as well as the OE avoidance work of clearing a suitable work area immediately surrounding each location. Throughout the project, continuing efforts of OE avoidance were required to safely remove the mosasaurs from progressive layers of soil. Rock Island and Omaha district personnel completed an investigation consisting of surface and subsurface soil sampling at soil boring locations, surface water and sediment sampling, and installation and sampling of monitoring wells. OE Investigators were looking for contamination from explosives, chemical warfare materiel, and hazardous and toxic waste left over from when munitions and other items were burned in trenches in these areas.
Archeologists work carefully to uncover the mosasaur bones.
During OE avoidance procedures, three small ordnance items were located which posed a potential threat to the site. The first of two live 40-millimeter shells was found on July 13 near the fossil dig. All ordnance items were detonated at Ellsworth Air Force Base, S.D., on July 29. Most ordnance items discovered during the mosasaur recovery project were surface debris. The second 40mm round was discovered in loose silt-like deposits two inches below the surface during surface clearance for the fossil recovery.