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<br />Mr Mark V.tnoiu <br />Sr Lnwronnu•nt.ll i,r ?,??1?n,?t;,r <br />F'Iuise 4 Qr<n amec <br />?1u(Ji.isl 11 :. <br />As part of the 4" POPE installation, a windrow should be constructed along the entire length of <br />the pipe using the same detail as presented in Figure 3. <br />Figure 5 presents a plan layout of shallow trenches to be excavated along the internal access <br />road/bench. The trenches are to be excavated to a maximum depth of 8 inches below the existing <br />DCF surface and spaced approximately 100 feet along the access road. The trenches should span <br />the entire width of the access road. Prior to excavation of the shallow trench, the area should be <br />scarified a minimum of 2 feet from the centerline of each trench to improve percolation. The <br />trenches are to be excavated after the area has been scarified. Once the trench has been <br />excavated, a PCPE pipe should be placed in the trench and backfilled with DCF and a windrow <br />formed above the pipe (see Figure 6). Since these are simple collection trenches, any size PCPE <br />pipe may be used in the trenched. <br />Btddins ff PCFE <br />_ _.P rr. <br />_ 7 <br /> <br />figure 5 Shallow <br />Cut a nuruinum of 6 trenches <br />t perpendicular to access road <br />Trench spacing approv- 100 <br />'. <br />Place PCTE pipe in trench and <br />_.r backtill <br />r <br />. ` . <br />Solution application header pipes <br />..r <br />A ^? <br />K <br />'L ~ <br />Figure 7 presents a general plan showing the area of the DCF that should be scarified. The <br />purpose of scarifying the DCF is to create a zone of enhanced percolation so that leach solutions <br />will enter the nearby Tertiary pipes. The DCF should be scarified to a depth of 4 to 8 inches. In <br />addition, windrows should be constructed upgradient of any new and existing solution collection <br />pipes within the area to be scarified. <br />It is important to note that the DCF should only be scarified prior to installation of any new <br />solution collection pipes to avoid damaging the pipes. Windrows would need to be constructed <br />after installation of new pipes. <br />SAPROJECTS1/ 193 ccdv gold mining phase 4 drainageW - desigMphase 4 drainage lelter.doc <br />4