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Services: Water Well Siting

    Several methods can be used for water well siting. The method chosen depends on a number of factors including the type of aquifer present at the site (i.e. water-saturated alluvium or water-bearing fractures in bedrock), size of the area of investigation, anticipated depth to groundwater, desired resolution of water-bearing features, geology and structural features in the area of investigation, expected competence of bedrock (i.e. sedimentary vs. igneous) if present, expected composition of water-bearing features (i.e. fractures in bedrock or coarse sands, gravels, cobbles etc.), and cultural features/sources of interference in the area of investigation. Spectrum commonly utilizes the following methods for water well siting:



  • Electrical Resistivity
  • Seismic Refraction
  • VLF  
  • Frequency Domain Electromagnetics  
  • Time Domain Electromagnetics 


  • A geophysical investigation was conducted at a property in Lake Perris, California to identify the center of a buried stream channel in granitic bedrock for placement of a municipal water well. Although 3 previous wells had been drilled into the estimated center of the buried channel (where both high water quality and high groundwater flow rates were anticipated), these wells had all yielded low water quality and poor groundwater flow rates. Spectrum was hired to provide an image of this paleochannel to a depth of at least 400 feet below ground surface.

    • Spectrum collected pole-dipole DC resistivity data along 4 transects using AGI’s R8/IP SuperSting unit, six-meter cable and overlapping arrays of 56 electrodes. The transect shown (image to right) was approximately 6000 feet long; subsequent transects were each approximately 2000 feet long. The electrical resistivity data revealed a broad low resistivity anomaly, (interpreted as the buried stream channel) at a depth of 124 meters (407 feet). Using the interpreted resistivity sections, a top-of-bedrock topo map was then generated to better illustrate the vertical and lateral extent of the buried stream channel. Subsequently, the Client placed a successful 4th well in the center of the interpreted buried stream channel and obtained high-quality water and 800 gpm of water flow.
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