GEOPHYSICS AND SITE CHARACTERIZATION AT THE HANFORD SITE THE SUCCESSFUL USE OF ELECTRICAL RESISTIVITY TO POSITION BOREHOLES TO DEFINE DEEP VADOSE ZONE CONTAMINATION - 11509

Conference · Fri Jan 14 00:00:00 EST 2011

OSTI ID:1004616

MJ, GANDER; KD, LEARY; MT, LEVITT; CW, MILLER

Historic boreholes confirmed the presence of nitrate and radionuclide contaminants at various intervals throughout a more than 60 m (200 ft) thick vadose zone, and a 2010 electrical resistivity survey mapped the known contamination and indicated areas of similar contaminants, both laterally and at depth; therefore, electrical resistivity mapping can be used to more accurately locate characterization boreholes. At the Hanford Nuclear Reservation in eastern Washington, production of uranium and plutonium resulted in the planned release of large quantities of contaminated wastewater to unlined excavations (cribs). From 1952 until 1960, the 216-U-8 Crib received approximately 379,000,000 L (100,000,000 gal) of wastewater containing 25,500 kg (56,218 lb) uranium; 1,029,000 kg (1,013 tons) of nitrate; 2.7 Ci of technetium-99; and other fission products including strontium-90 and cesium-137. The 216-U-8 Crib reportedly holds the largest inventory of waste uranium of any crib on the Hanford Site. Electrical resistivity is a geophysical technique capable of identifying contrasting physical properties; specifically, electrically conductive material, relative to resistive native soil, can be mapped in the subsurface. At the 216-U-8 Crib, high nitrate concentrations (from the release of nitric acid [HNO{sub 3}] and associated uranium and other fission products) were detected in 1994 and 2004 boreholes at various depths, such as at the base of the Crib at 9 m (30 ft) below ground surface (bgs) and sporadically to depths in excess of 60 m (200 ft) bgs. These contaminant concentrations were directly correlative with the presence of observed low electrical resistivity responses delineated during the summer 2010 geophysical survey. Based on this correlation and the recently completed mapping of the electrically conductive material, additional boreholes are planned for early 2011 to identify nitrate and radionuclide contamination: (a) throughout the entire vertical length of the vadose zone (i.e., 79 m [260 ft] bgs) within the footprint of the Crib, and (b) 15 to 30 m (50 to 100 ft) east of the Crib footprint, where contaminants are inferred to have migrated through relatively permeable soils. Confirmation of the presence of contamination in historic boreholes correlates well with mapping from the 2010 survey, and serves as a basis to site future characterization boreholes that will likely intersect contamination both laterally and at depth.

• Research Organization: Hanford Site (HNF), Richland, WA (United States)
• Sponsoring Organization: USDOE Assistant Secretary for Environmental Management (EM)
• DOE Contract Number: DE-AC06-08RL14788
• OSTI ID: 1004616
• Report Number(s): CHPRC-01168-FP Rev 0; TRN: US201103%%410
• Resource Relation: Conference: WM2011 WASTE MANAGEMENT CONFERENCE DOE 03/07/2011 THRU 03/11/2011 PHOENIX AZ
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
58 GEOSCIENCES
BOREHOLES
CESIUM 137
CONTAMINATION
ELECTRIC CONDUCTIVITY
FISSION PRODUCTS
GEOPHYSICAL SURVEYS
GEOPHYSICS
NITRATES
NITRIC ACID
PHYSICAL PROPERTIES
PLUTONIUM
PRODUCTION
RADIOISOTOPES
SITE CHARACTERIZATION
SOILS
STRONTIUM 90
TECHNETIUM 99
URANIUM
WASTE MANAGEMENT
WASTES