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� 111 Pressure Cats Method. In the pressure cap method, the grouting is done with the hole drilled about 2 feet I (0.6 metre) below the bottom of the. conductor casing and the remainder of the well drilled after the grout is in place and W set. The grout is placed through a grout pipe set inside the iz conductor casing. +� 1. The casing is suspended about 2 feet 0 u m w (0.6 metre) above the bottom of the drilled hole and filled ❑ with water. O 2. A pressure cap is placed over the conductor F 11 casing and grout pipe extended through thecap and casing to the bottom of the hole. CE L, x 3. The grout is forced through the pipe, up - - =4.- - - into the annular space around the outside of the conductor I < w 4 if casing, to the ground surface. 4. When the grout has set, the pressure cap and the plug formed during grouting are removed and drilling J LL of the rest of the well is continued. o x 0 Because there is the possibility that coarse aggre- o Z gate will "jam" the grout pipe, concrete cannot be used as a ,4 sealant when this method is used. # UJ Continuous Injection. This method, called the Normal Displacement M thod in the oil industry (which developed 6W 2 it), involves pumping grout through a tube or pipe centered in � 'w" ' ' m c the casing via a "float shoe" fitted at the bottom of the '� LL,}_ _ # 3 casing. The grout is forced up into the annular space to the ground surface as is the case with the pressure cap method J o z O (above). The tube is detached and flushed. The float shoe, � - M = which has a back pressure valve, is drilled out. Because '" F there is the possibility that coarse aggregate will "jam" the w i LU grout pipe, concrete cannot be used with this method. Ag yr 0 1 ac — x �w a Sealing-off Strata x ' m rc r When the hole for a well is drilled, a strata may be found that produces water of undesirable quality. To prevent =W # # the movement of this water into other strata and to maintain i 1i the quality of the water to be produced by the well, such = i r strata must be sealed-off. Also, where a highly porous non- water producing strata is encountered, it too must be sealed- off to prevent the loss of water or hydraulic pressure from the well. } . The following methods can be used in sealing-off u � strata or zones (see Figure 11). In addition, several of the methods described for sealing the upper annular space can Q also be used. W Pressure-Grouting Method. This method can be employed where a substantial annular space exists between the well casing and the wall of the drilled hole.