Mixed Waste Landfill Annual Long-Term Monitoring & Maintenance Report, April 2014 -- March 2015 for Sandia National Laboratories/New Mexico, EPA ID Number NM5890110518

Sandia National Laboratories/NM
U.S. Department of Energy

646 pgs.

Department of Energy (DOE) and the National Nuclear Security Administration (NNSA)


he Department of Energy/National Nuclear Security Administration (DOE/NNSA) and Sandia Corporation submitted the Mixed Waste Landfill (MWL) Annual Long-Term Monitoring and Maintenance Report for the April 2014 through March 2015 reporting period to the New Mexico Environment Department (NMED). This report satisfies the requirements of Section 4.8.1 of the MWL Long-Term Monitoring and Maintenance Plan (LTMMP) for documentation of all monitoring, inspection, and maintenance/repair activities conducted during each reporting period. The annual reporting periods run from April 1 to March 31. The MWL is a 2.6-acre Solid Waste Management Unit (SWMU 76) which has undergone corrective action. The MWL is located in the north central portion of Sandia National Laboratories/New Mexico (SNL/NM) Technical Area III. During the operational period (March 1959 through December 1988), the MWL accepted low-level radioactive waste and minor amounts of mixed waste from SNL/NM research facilities and off-site DOE and U.S. Department of Defense generators. On May 26, 2005, the NMED issued the Final Order selecting a vegetative soil cover with biointrusion barrier (referred to as the ET Cover) as the final remedy for the MWL. Deployment of the MWL ET Cover was completed in September 2009. This is the second MWL Annual LTMM Report and the first to include a complete reporting period since NMED approved the LTMMP on January 8, 2014, and it includes information for monitoring, inspection, maintenance, and repair activities conducted during the reporting period. This report is comprised of 12 chapters that include monitoring results for radon in air, tritium in surface soil, biota, groundwater, and vadose zone soil-vapor and soil moisture at the MWL. Inspection, maintenance, and repair activities for monitoring well systems and equipment, the storm-water diversion structure, the MWL ET cover system, and perimeter fence are also presented. One chapter is devoted to a summary of regulatory activities pertaining to the MWL that occurred during the reporting period. The report includes five annexes with supporting field and analytical documentation for monitoring activities. Forms used to document inspection activities are provided in a sixth annex and a seventh contains the annual biology report. The monitoring and inspection results presented in the report indicate the final remedy, which includes the ET Cover and related physical and institutional controls, is performing as designed. No monitoring trigger levels were exceeded. Site conditions continue to be protective of groundwater, human health, and the environment. 646 pgs.