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Water Quality Data
STANDARD GUIDELINES FOR DESIGN
AND PROPER CONSTRUCTION
OF A WATER WELL
By Roy F. Senior, Jr.*
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SITE SELECTION
Site selection should be made with consideration being given to probable water quality and volume, followed by location of a power source and then transportation of water to the desired area.
Available driller and electric logs of the surrounding area should be obtained, including oil and gas logs. (The probability of locating a successful, deep well below the Corcoran Clay may often be as high as 90%, based on research and review of existing logs.)
After the site location has been determined, specifications that follow accepted industry standards should he obtained and used as a basis for the well contract and construction. (Specifications are available from many sources, such as the Bureau of Reclamation, various governmental agencies, and geologist or engineering firms. All employ similar industry standard procedures that have- been developed and proven successful over the years.)
PILOT HOLE (TEST HOLE)
Pilot holes should always be drilled and water samples collected and analyzed if water quality is of a questionable nature.
A pilot hole should be drilled, samples of drill cuttings taken at 10' intervals (or at formation changes) and sieve analysis performed on the sands. An electric log of the pilot hole should then be performed to identify footage and characteristics of the producing sands with some indication of water quality. Based on a review of this information, a proper well design can be achieved.
After sands and electric log analysis, the pilot hole should be properly abandoned, if the pilot hole indicates the formation will not support a well of sufficient capacity or water quality.
A word about shallow pilot holes…. It may be necessary to drill a shallow pilot hole, analyze sands and the electric log of the proposed well site above the Corcoran Clay to determine water quality and production capacity. Water samples may be taken above the Corcoran Clay in a standard rotary test hole by installing a small diameter, 2" pipe, and pumping water samples from the target zone.
* Note: These remarks were presented by the author at a District
workshop in 1992.
Roy can be reached
at (559) 233-6131. Last updated January
2001