Sampling and Analysis Plan (SAP) for Assessment of LANL-Derived Residual Radionuclides in Soils within Tract A-16-d for Land Conveyance and Transfer

Abstract

A-16-D Los Alamos Canyon DP Canyon Additional AOCs and PRSs include:  C-00-006 (Los Alamos Canyon)  C-00-021 (DP Canyon) DP Canyon enters TA-21 and continues until it joins Los Alamos Canyon along the boundary between TA-21 and TA-73 at an elevation of approximately 6620 feet. Previous environmental investigations at AOC C-00-021 include regular environmental monitoring that has been conducted in DP Canyon since the 1970s as part of the LANL Environmental Surveillance Program. Sediment samples containing elevated levels of Cesium-137, Plutonium-238/-239, Strontium-90, Thorium-230/-232, and Uranium-238 have been detected. Some concentrations exceeded screening levels. In addition, the Environmental Restoration Project has conducted numerous investigations in and around TA-21 in association with SWMUs/AOCs at TA-21. One of the most significant historical contamination sources at TA-21 is SWMU 21-011(k), which is an outfall that discharged effluent from the Radioactive Liquid Waste Treatment Facilities into DP Canyon from 1956 to 1985. SWMU 21-011(k) is upgradient of Tract A-16-D. Other potential contaminant sources at TA-21 include MDA A (SWMU 21-014), MDA T [consolidated unit 21-016(a)-99], MDA U [consolidated unit 21-017(a)-99], septic tanks and outfalls, and a petroleum product tank farm (SWMU 21-029).  21-013(a) (see Figure 4) Disposal area for sand from the drying beds of the sanitary waste treatment plant.  21-013(c) (see Figure 4) Former location of a surface disposal area located at the eastern end of DP Mesa. The site consisted only of construction debris, including piles of fill, asphalt, and concrete, an excavated trench, an earthen berm that contained scattered concrete, asphalt, and metal debris, and four large concrete pylons. Other surface debris included glass, scrap metal, wood, cans, paper, and plastic. It is not known when the materials were disposed of at this site. During a 1995 cleanup, all debris was removed.  21-026(a) (see Figure 4) The sewage treatment plant 21-026 (a) treated sanitary waste and non-contact cooling water from TA-21 facilities.  21-026(b) (see Figure 4) Treated effluent was discharged to sand filter/sludge drying beds.  21-026(c) (see Figure 4) Chlorine contact chamber located next to the sewage plant.  21-026(d) (see Figure 4) Outfall from Building 21-227. Recreational SAL [pCi/g] 15 mrem/yr (150 µSv/yr) Construction SAL [pCi/g] 15 mrem/yr (150 µSv/yr