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Bedrock Wells
Wells located at higher elevations above the valley bottoms in the British Columbia Southern Interior are often completed in solid bedrock. Wells drilled in bedrock are usually exploratory, since the presence, depth, and size of water bearing fractures, fissures and faults in bedrock are not easily predictable from the surface. While well yields in bedrock are sometimes substantial, most often they are only adequate for domestic use, and not much more. As in overburden, wells are drilled using welded steel casing, advanced through the overburden using air powered percussion methods, and cuttings are cleaned out of the casing as drilling progresses by air lifting. Once bedrock is reached, the upper and lower ends of the casing are sealed to prevent surface water contamination, as drilling proceeds into the bedrock, uncased and open hole. Water injection is frequently used with air lift to help clean the hole and reduce surface dust. Water production from water bearing fractures, fissures and faults in bedrock is seen very quickly at the surface, frequently from fractured water bearing quartz veins in surrounding rock. Wells are developed, using compressed air and water, a step which removes the loose material from the formation through the wellbore, enlarging water flow passages, maximizing production, while cleaning the wellbore. Occasionally PVC liners are set throughout the length of the wellbore if the submersible pump will require protection from loose material located uphole. Chlorination, capping, and tagging are the final steps in completing wells, ready for pumping. Cascade’s well logs are all entered into a computer database dating back to 1982 which provides rapid retrieval and access for well planning
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