Distribution of moisture and radioactivity in the soil and tuff at the contaminated waste pit near Technical area 21, Los Alamos, New Mexico

Abstract

The contaminated waste pit near Technical Area 21 was investigated to determine if waterborne radioactive contaminants had migrated from the pit into the adjacent soil and tuff. Thirteen test holes, ranging in depth from 25 to 50 feet, were drilled through the soil into the underlying tuff in the vicinity of the waste pit. No holes were drilled through the base of the pit as only the surface of the pit and adjacent land is considered for commercial use. The distribution of moisture in the soil and tuff penetrated by the test holes was determined by a neutron-scattering moisture probe. Samples of drill cuttings of the soil and tuff were analyzed for gross alpha and gross beta-gamma radioactivities, and plutonium and uranium.The moisture content of the tuff adjacent to the test holes indicated that the tuff was not saturated. Radiochemical analyses of soil and tuff indicated no radioactive contamination.

History and environmental setting of LASL near-surface land disposal facilities for radioactive wastes (Areas A, B, C, D, E, F, G, and T). A source document

“…The thickness of the Bandelier Tuff beneath the disposal pits is estimated to exceed 243.8 m (800 ft). 200 The tuff is in the zone of aeration with the zone of saturation (water table) at a depth of approximately 365.8 m (1200 ft) below the surface of the mesa. 300…”

“…The area was free from radioactivity (sic) contamination until we reached the fenced area, where 2000 c/m was recorded. The dirt in the area showed a count of 20,000 elm with bits of wood going as high as 200,000 c/m. Bits of twisted metal from the room were found in the shot area.…”

Environmental surveillance of low-level radioactive waste management areas at Los Alamos during 1985

“…It was concluded from this study that plutonium had penetrated to a depth o f a t least 8.8 m in the tuff beneath the pits and that penetration took place mainly along fractures in the tuff. In 1967 several test holes drilled outside the pits showed no alpha, beta, or gamma contamination but tritium was found in the pore water (Purtymun and Kennedy, 1966).…”

Radiochemical analyses of samples from beneath a solid radioactive waste disposal pit at Los Alamos, New Mexico

“…Disposal records identified the presence of 3 H, "Sr, mixed activation and fission products, 23t -"°Pu, "'Am, and uranium as contaminants in the waste.…”