The proposed monitoring and testing wells would be used to conduct hydrologic testing in Spring Valley. Information obtained from the testing would be used to assess aquifer characteristics, including storage parameters and hydraulic conductivity. Because there is limited hydrologic testing information available from this area, the data collected would benefit the Bureau of Land Management (BLM) and the public through a better understanding of the carbonate and alluvial aquifers in this area. Information collected during the testing could also be used in future groundwater modeling analyses and impact assessments.

Four well sites, each 2.5 acres in size, are requested. These test well sites were selected based upon proximity to hydrographic basin boundaries and geologic features, likely access to subsurface carbonate rocks, and the ability to use existing access roads. At each well site, an observation well and a test well would be constructed. The wells would be drilled to between 1,000 and 1,250 feet in depth, with the final depth dependant upon actual groundwater elevations. The observation wells would be up to 8-inches in diameter, and the test wells would be up to 20-inches in diameter. The observation and test wells would be spaced 100 to 300 feet apart, within the 2.5-acre well site.

Access to the sites would be from existing roads, and no new access roads would be required. If an existing road requires repairs or stabilization, any activities would be confined to the existing road boundaries. Stabilization, if needed, could include use of gravel, dirt, or straw fill of ruts or unstable surfaces. Grading of existing roads is not anticipated to be necessary, but if needed in localized areas would be confined to the existing road area.

At the completion of the well drilling, a 72-hour pump test would be conducted. A submersible pump would be lowered into the well, to approximately 100-150 feet below the groundwater elevation. Groundwater would be continuously pumped for 72-hours at a rate of up to 3,000 gpm. Water level measurements would be taken simultaneously in the adjacent observation well.

A step-down pump test would also be conducted at each of the test wells. This test involves pumping at different rates over several hour durations, while measuring water level changes. The groundwater discharge rate would be up to 3,000 gpm. The step-down pump test is anticipated to last about one day at each test well.

The pumps used for the hydrologic testing would be powered by a portable diesel engine generator, either trailer-mounted or on the bed of a truck. In addition to the drilling crew, a hydrologist would be present on-site for the duration of the hydrologic testing.

A temporary discharge permit(s) for the hydrologic testing would be obtained from Nevada Division of Environmental Protection, Bureau of Water Pollution Control. Water generated during the pump tests would be discharged into the natural drainage network around the site. A diffuser or other erosion control measures would be used to reduce discharge rates to prevent scouring. The discharged water would rapidly evaporate or percolate into the alluvial sediments in the area. No long-term ponding of water would result from the tests.

Hydrologic testing activities are anticipated to be completed by July, 2007.

Legal Location: see map below.
Date Posted: 8/08/2006