The first operation after drilling the hole (fig. 9-14)is to set the screens and casing (fig. 9-15). The casingprevents collapse of the drilled hole walls inunconsolidated formations. The screens preventcollapse of the drilled hole wall in the aquifer whileallowing water to enter the casing freely. After the casingis set, the well is gravel-packed (fig. 9-16). Gravelpacking is placing graded aggregate on the outside ofthe casing to allow for more production and prevent“fines” from entering the well pump, tanks, andsystems.When the screens, casing, and gravel pack havebeen completed, the well is ready for development.Development is accomplished by removing the drillingfluid from the aquifer and the employment of any meansthat induces an alternating flow of water in and outthrough the screens. This action stirs up theunconsolidated material in the aquifer and allowsremoval of the finer particles. Gradually, the coarsestparticles become stabilized around the screens, and thelast vestiges of drilling fluid are removed, permitting thewell to yield its maximum capacity.A variety of methods are used for setting screens,removing drilling fluid, and developing aquifers. Themethod used for either of these operations is oftendetermined by the tools and equipment available.When development of a well is complete, it isrequired to grout as a sanitary protective measure toprevent seepage of surface water or contaminated waterfrom water-bearing formations above into the aquifer.Grouting is accomplished by cementing from the top ofthe gravel pack to the annular space between the wellwall and casing (fig. 9-17).WELL DRILLING SAFETYSafetyisparamountin all construction operations.You must always be safety conscious and on the alertfor potential dangers to personnel and equipment. Safetyconsiderations cannot be overemphasized.1. Hardhats area must and should always be worn.2. Gloves should be worn to protect hands whenhandling wire rope.Figure 9-14.-Drilling the hole.Figure 9-15.-Casing the hole.9-16
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