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Water Well Rehabilitation
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Water Well Rehabilitation
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When well maintenance is deemed necessary the first thing you should do is refer to the design, construction and operational records of the well.
For more information, refer to the list of pages on the left.
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The first step requires removing the production pump. In the case where maintenance requirements are not severe, the contractor can temporarily replace the production pump and install a pump he uses for well maintenance. Then the well can be treated with relatively non-corrosive chemicals that can be introduced between the pump and the well casing. (Note: Because chemicals and sand may damage the pump, the well's regular pump should always be removed prior to maintenance.) The well is then surged by repeatedly stopping and starting the pump. After an appropriate detention time, the well is pumped to waste and returned to service. While this procedure is inexpensive, it is very limited in its effectiveness. Therefore, other methods are used in more severe cases.
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Water Flowing @ 1050 GPM from a 6" pipe |
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As soon as the pump is removed, the well should be sounded or checked for correct depth. This can be done with a weighted steel line or with the bailer of a workover rig. This depth should be compared to installation records, including geophysical logs, for evidence of holes or casing collapse or sediment accumulation in the well. If geophysical logs (gamma, resistively, spontaneous potential, or others) from the time of construction are not available, you will have to rely on other data such as the drillers log and a video survey. Utilizing the drillers log, casing and screened zones can be identified for the proper application of maintenance procedures. In many cases the use of a down hole video will aid in identifying problem areas in the well, often the most reliable means of obtaining specific information concerning the condition of the well. Both of these techniques have been successfully used in evaluating well problems. Television and photographic survey can pinpoint the location of casing problems, screen blockage of failure, and the location and nature of production zones in rock wells. When screens or zones are heavily encrusted, the television camera can help obtain a sample of the encrusting materials while performing the inspection. A sample can be taken by lowering a small bucket-shaped container ahead of the camera to scrape off a portion of the material in question. These samples can then be analyzed, and the results can be used to select the appropriate chemical treatment.
CHEMICAL TREATMENT
Due to constant changing regulations, with local and federal agencies, we are not addressing chemical treatments in this web site.
MECHANICAL REDEVELOPMENT
In conjunction with, or subsequent to chemical treatment, it is almost always necessary to mechanically redevelop the well. Redevelopment procedures are similar to the procedures used to develop new wells. The intent of these processes is to open the productive zones of the well, facilitating the movement of water into the well. In the case of a rock well, this entails opening fractures and bedding planes along which water moves toward the well. In screened wells, this involves opening the screen slots and the pore spaces in the aquifer outside the screen. In all cases, redevelopment procedures must assist in loosening the debris, scale, silt, clay and other materials treated by the chemicals employed. These processes must also make it possible for this loosened material to be pumped or bailed from the well.
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