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Corrective action unit modeling approach for the underground test area, Nevada Test Site, Nye County, Nevada

Description: The modeling approach serves as a template for the development, application, and interpretation of the Corrective Action Unit (CAU) - scale saturated groundwater flow and transport model (herein called the CAU model) to be used for forecasting radionuclide migration in all Nevada Test Site (NTS) CAUs, consistent with the Federal Facility Agreement and Consent Order (FFACO) and Underground Test Area (UGTA) strategy. A summary of the project background, the FFACO and strategy, and the roles of participating agencies, is provided followed by a description of the contents of the document.
Date: March 1, 1998
Partner: UNT Libraries Government Documents Department

Evaluation of the Rulison drilling effluent pond as trout habitat

Description: The Rulison Site is located in Section 25, township 7 South, Range 95 West, Garfield County, Colorado. The site is approximately 19 kilometers (km) (12 miles [mi]) southwest of Rifle Colorado, and approximately 65 km (40 mi) northeast of Grand Junction, Colorado. Project Ruhson was an experiment conducted jointly by the U.S. Atomic Energy Commission and Austral Oil Company to test the feasibility of using a nuclear device to increase natural gas production in low permeability geological formations. The experiment was conducted on September 10, 1969, and consisted of detonating a 43-kiloton nuclear device at a depth of 2,568 meters (m) (8,426 feet [ft]) below the ground surface (DOE, 1994). The Rulison Drilling Effluent Pond (called `the pond`) is an engineered structure covering approximately 0.2 hectare (0.5 acre), which was excavated and used to store drilling fluids during drilling of the device emplacement well. The drilling fluids consisted of bentonitic drilling mud with additives such as diesel fuel and chrome lignosulfonate. Most of the drilling muds were removed from the pond when the site was decommissioned in 1976, and the pond was subsequently stocked with rainbow trout by the land owner and used as a fishing pond. In 1994 and 1995, the U.S. Department of Energy (DOE) conducted sampling of the pond to evaluate residual contamination from the drilling fluids. Based on the results of this sampling, the DOE conducted a voluntary cleanup action in order to reduce the levels of total petroleum hydrocarbons and chromium in pond sediments. The cleanup was conducted between August and mid-November of 1995. At the end of cleanup activities, the pond was lined with a clay geofabric and left dry. The geofabric was covered with sod to protect it. The pond has since been refilled by snowmelt and inflow from a spring. Prior to ...
Date: June 23, 1998
Partner: UNT Libraries Government Documents Department

Summary of micrographic analysis of fracture coating phases on drill cores from Pahute Mesa, Nevada Test Site. Revision 1

Description: The flow path between Pahute Mesa and the groundwater discharge area in Oasis Valley (approximately 18 miles to the southwest) is of concern due to the relatively short travel distance between a recharge area where underground nuclear testing has been conducted and the off-site water users. Groundwater flow and transport modeling by IT Corporation (IT) has shown rapid tritium transport in the volcanic rock aquifers along this flow path. The resultant estimates of rapid transport were based on water level data, limited hydraulic conductivity data, estimates of groundwater discharge rates in Oasis Valley, assumed porosities, and estimated retardation rates. Many of these parameters are poorly constrained and may vary considerably. Sampling and analytical techniques are being applied as an independent means to determine transport rates by providing an understanding of the geochemical processes that control solute movement along the flow path. As part of these geochemical investigations, this report summarizes the analysis of fracture coating mineral phases from drill core samples from the Pahute mesa area of the Nevada Test Site (NTS). Archived samples were collected based on the presence of natural fractures and on the types and abundance of secondary mineral phases present on those fracture surfaces. Mineral phases present along fracture surfaces are significant because, through the process of water-rock interaction, they can either contribute (as a result of dissolution) or remove (as a result of precipitation or adsorption) constituents from solution. Particular attention was paid to secondary calcite occurrences because they represent a potential source of exchangeable carbon and can interact with groundwater resulting in a modified isotopic signature and apparent water age.
Date: December 1, 1998
Partner: UNT Libraries Government Documents Department