1998-02-01_REVISION - M1977215 - Laserfiche WebLink

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PHILLIPS MINING, GEOTECHNICAL 8 GROUTING, INC. 9360 Level with the lower workings. Thus, when the level of water behind the plug has risen to approximately 25 ft above the plug, i.e., the collar of the raise, the water will overflow down to a lower mining level. The maximum pressure on the plug is therefore limited to 11 psi. 4. PLUG CONSTRUCTION The plug will be constructed within the existing configuration of the adit. The existing sets, cribbing and blocking will have to remain in place to maintain the security of the drift. However, to optimize the plug construction, the loose rock that has accumulated behind the lagging around the periphery of the existing excavation should be removed so that, where possible, the plug is cast against the back, walls and floor of the adit. Therefore, where it is safe to do so, some of the lagging between sets should be selectively and carefully removed so that subsequently placed plug concrete will directly contact the ground around the drift. Where possible, long lengths of cribbing and spreaders, etc., that are aligned axially along the drift and would provide a potential leakage path through the plug, should have a section cut out of them. The length of the plug will be of the order of 24 feet. Its exact length will be determined by the appropriate placement of the forms within the existing sets such that the plug length is within the required length range. Atypical layout for the plug is shown in Figure 1. During the plug construction, any drainage water that is being produced in the adit will be controlled by a temporary dam located immediately upstream of the plug location, so that it does not enter the main work area. This dam can be constructed with sandbags, but these must be placed directly against the clean floor and base of the ribs to adequately control all the water flowing down the adit. The water will be piped through the plug Page 3