Union Pacific Drying Beds Council Bluffs, Iowa The former treatment facility consists of a Surface Impoundment Pond (SIP) and three rectangular drying beds. A previous report (Remedial Options Analysis Report, USPCI, 1991) stated that the SIP was used by Union Pacific Railroad (UPRR) as a catch basin for collecting fluids from the cleaning of rail cars. Other references report that the SIP was used for disposal of wastewater treatment sludge generated in the Council Bluffs, IA, Omaha, NE and North Platte, NE shop facilities. The site was first assessed by U.S. Pollution Control, Inc. (USPCI) in January 1990. The initial investigation analyzed the drying beds and SIP sludge for volatile organic compounds (VOCs), base neutral acids (BNAs), metals, and pesticides. Additional fieldwork was performed by USPCI in 1991 whereby sludge samples from the SIP were analyzed for Toxic Characteristic Leaching Potential (TCLP) and Fuels Placement. A Site Investigation Work Plan was generated by EPOCH Environmental Group, LLC and submitted to the Iowa Department of Natural Resources (IDNR) in October 2000. Collection of soil samples from the drying beds and sludge samples from the SIP were conducted, in addition to installation of 4 monitoring well pairs. Subsequent investigation activities were conducted in July 2001 and May 2002 to provide horizontal delineation of soil impact around the perimeter of the SIP. During August and September 2003, Delta Environmental Consultants, Inc (Delta) conducted additional sampling within the SIP to determine waste classification and to assist in estimating disposal costs. In August, sludge and clay liner samples were collected and analyzed in each of the twenty-four 40-feet by 40-feet grids. Generally, the sludge layer extended from the ground surface to a depth of 3 feet, while the clay liner layer extended from a depth of 3 feet to 8 feet bgs. Slight variations to these intervals were reported. Results from the August grid sampling event were utilized during the September quadrant sampling event to further delineate waste characterization. Quadrant sampling was conducted within selected grids to assist in further refining the volume of soils that exhibited hazardous characteristics. Results of the assessment activities at the site were presented in the Soil Investigation Report dated September 27, 2004. Concentrations of vinyl chloride, tetrachloroethene, trichloroethene, 1,1-dichloroethene, lead, and selenium were reported above EPA TCLP standards at locations in the SIP. An average Total Extractable Hydrocarbons concentration of 328,000 mg/kg was calculated from three sludge sample locations. A Total Extractable Hydrocarbons concentration of 5,010 mg/kg was reported for a sample from the clay liner. A Remedial Action Plan (RAP) has been developed that incorporates soil excavation, on-site stabilization, and disposal to reduce future leaching of impacted materials in the SIP to the groundwater.