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<br />,December 1986 <br />14 <br /> <br />863-2052 <br />all surface water around the excess spoil structures except for <br />direct precipitation. This should ensure that there is no signi- <br />ficant build up of water pressures within the excess spoil <br />structures during the intial mining operation when the excess <br />spoil structures are being constructed and reclaimed. There will <br />be no construction of valley fills for disposal of excess spoil <br />except where drainage of the valley has been intersected by the <br />box cut or has been diverted so that it does not enter the excess <br />spoil structure. As described in Section 5.0, underdrains will <br />be constructed at the base of all valley fills. <br />Three seeps were identified in the proposed excess spoil areas <br />during the field reconnaissance. These seeps are located i^ the <br />drainages immediately west of borings B-1 and B-3 (Figure 2). No <br />other surface flow was identified in the excess spoil areas at <br />the time of the reconnaissance. An underdrain will be con- <br />structed directly above each seep or spring present in the excess <br />spoil areas at the time of foundation preparation. Because the <br />seeps identified are located in drainages where underdrains were <br />previously planned (Golder, 1986), no additional underdrain <br />construction is anticipated due to these seeps. <br />4.5 Ground Water <br />The Little Middle Creek tract lies at the southern end of the <br />Eckman Park subbasin of the Twentymile Park structual and ground- <br />water basin. Regional ground-water conditions in the vicinity of <br />the tract are described in detail in other sections of the permit <br />application. For the stability of the excess spoil, only ground- <br />water conditions above the seam being mined are of importance. <br />Golder Associates <br />