260 CMS Report

Phase III RFI Report

The HEPS Team for Remedial Actions Field Site is responsible for RS/ECR project activities at Los Alamos National Laboratory (LANL) technical areas (TAs) 6, 8, 9, 11, 16, 22, 28, 37, 40, 58, 62, and 69. Each of these sites contains, or contained, facilities for high explosives (HE) research and development, detonator development, nondestructive and environmental testing of nuclear weapons components, HE storage, and HE firing. The potential release sites (PRS) include contaminated soils associated with

The principal constituents of concern at these sites are the HE--particularly RDX, TNT, and HMX--and inorganics, particularly barium.

The HEPS Team is responsible for characterizing and/or remediating 635 PRSs. As of October 2004, over 350 of these were proposed for no further action (NFA) based on human health concerns. These NFA proposals were based on (1) archival research that suggested the sites posed minimal risk or (2) environmental sampling that showed low levels of hazardous constituents. Over thirty sites have been cleaned up voluntarily, including HE sumps and drainlines at the 90s Line (320 cubic yards of soil removed), drainlines at Building 27 and V-Site (120 cubic yards of soil removed), and debris at Material Disposal Area (MDA) M (5460 cubic yards of soil removed). Evaluation of ecological risk and risk to surface waters are ongoing at most of these sites.

The most highly contaminated site within HEPS is PRS 16-021(c), the outfall from HE-machining building 260. Soils, surface waters, and groundwaters are all contaminated with HE and barium at high levels, and with many other constituents at low levels, due to discharge from the TA-16-260 outfall. HE levels ranged up to > 20 wt % in the most highly contaminated soils directly downstream from the outfall. Barium is at levels greater than 10,000 ppm for 600 ft downgradient from the outfall. These soils were cleaned up in an Interim Measure (IM) during FY 2000 and 2001. Surface waters and sediments in Canon de Valle are all contaminated with HE and barium. Nearby springs--SWSC spring, Burning Ground spring, and Martin spring -- are also contaminated with ppb levels of HE and above-background levels of barium. Parts-per-billion levels of HE have also been detected in ephemeral perched aquifers at a depth of ~100 ft in two boreholes, and in the well known as R-25 in deep perched aquifer at a depth of ~750-1500ft. PRS 16-021(c) is currently undergoing the first corrective measures study/corrective measures implementation (CMS/CMI) at LANL.

Two deep boreholes, CdV-R-15-3 and CdV-R-37-2 and three intermediate-depth boreholes, CdV-16-1(i), CdV-16-2(i), and CdV-16-3(i), have recently been drilled down gradient from TA-16-250 and R-25. No HE has been detected in one deep borehole during quarterly sampling to date. Two of the intermediate boreholes contain HE.

Material Disposal Area P (MDA-P) is also located at TA-16, although due to the significant scope of the cleanup at this site, it is administered separately from the HEPS Team. Approximately 55000 cubic yards of HE and barium contaminated soil and debris were cleaned up at this site. Due to the hazardous nature of the cleanup, most excavation was completed remotely.

Other HEPS PRSs that are known to be contaminated, or are likely to be contaminated, at high levels include the TA-16 Burning Ground, Material Disposal Area R (MDA-R), several HE waste ponds, and K-Site. Initial data suggest that these sites are contaminated with chunk HE and/or moderately high levels (thousands of ppm) of HE. MDA-R was also partially cleaned up in an IM cleanup following the Cerro Grande fire.