Hydrogeology

Water Resources          Geophysical Mapping          Geotechnical Studies

NSN has been involved with developing water resources and the design of waste water disposal alternatives for 31 years. Our work experience has covered every aspect of surface and ground water development permitting and impact analysis.  The following is a listing of specific areas of expertise:

• Desalination Water Supply Development
• Sinkhole Investigations
• Monitoring of the fresh/saltwater Interface 
• Potable, agricultural, industrial water supply development and permitting 
• Hydrogeologic mapping and testing
• Aquifer analysis through pump testing and 3-D flow computer simulation modeling for impact evaluation of ground water withdrawal and permitting
• Geothermal well systems 
• Aerial photography interpretation 
• Well field design, testing and construction technology (municipal, industrial, agricultural) 
• Down-hole geophysical surveys
• Surface water flow measurement and water quality monitoring and modeling

• Expert Witness
• Environmental Site Assessments
• Geologic, Hydrologic and Water Quality investigation, mapping and interpretation 
• Evaluate impacts of ground water withdrawals on saltwater intrusion, wetlands, sinkhole formation
• Water use and Environmental Permitting
• Waste water disposal design and alternative evaluations, design and permitting (spray irrigation, groundwater injection, and wetlands)
• Mine Site geologic evaluation 
• Soils investigation 
• Ground water level and quality monitoring and mapping 
• Water resource assessment, hydrogeologic basin definition and water budget analysis 

Water Resources

Fort Yates, North Dakota - NSN conducted a study to locate sand and gravel deposits along the banks and mud flats of the Oahe Reservoir in North Dakota. The reservoir is located on the Missouri River NSN was approached to conduct a series of investigations using Multi-electrode Electrical Resisitivity (MER) surveys to locate potential sand and gravel deposits that could be tapped with horizontal wells for water supply. The depth of investigation of a survey is a function of the number of electrodes used and the distance between electrodes. In the Fort Yates study, gravel deposits at a gravel mine were investigated and used to “calibrate” the survey results to known deposits of gravel.  The results are then used to identify the occurrence of probable deposits based on the similarities in the response. The sand and gravel deposits are highly resistive compared to the silt dominated sediments surrounding the sand and gravel.

Site Map

MER Transect 8

Transect 8 - High resistivity sands and gravels in the known gravel deposit are evident with resistivities above 100 Ohm-m and are color coded spanning from yellow through red, with red indicating the most resistive materials. The low resitivities represented by the green to blue colors are primarily silty sediments with some clays. A second rendition of the cross sections are included where the color scale has been adjusted to emphasize the high resistivity sands and gravels.

MER Transect 10

MER Transect 9

MER Transect 10 was run parallel to the reservoir shoreline during low water on mud flats. The effective depth of the survey extends to greater than 100 feet in depth. The shallower sediments appear to be silty sands but extensive sands and gravels are suggested at depths below 80 feet.

MER Transect 9 identifies possible candidate sand and gravel deposits. Additional MER surveys coupled with a limited drilling and sampling or CPT sounding program will identify the extent and lateral continuity of gravel deposits.  MER surveys will be used to map the path of the sinuous sand and gravels so that horizontal wells may be properly designed and located.

Geologic, Hydrologic and Water Quality investigation, mapping and interpretation 

Eldridge-Wilde well field - Hydrogeologic testing, geologic mapping, water and soil quality sampling of three illegal solid waste landfills containing toxic chemical.  Pollutants originating from these below grade disposal sites entered the Eldridge-Wilde well field, resulting in the shut down of 13 production wells (20MGD).  Work included supervision of the clean-up of 30 acres of contaminated soil and extensive expert testimony over a four year period resulting in a 4.5 million-dollar settlement against the owners of the land fills.

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Desalination Water Supply Development

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