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<br />From the survey results and comparison of these results with the river location shown on the Mine Base <br />Map, a meander bend is also beginning to form upstream at Section 4 as shown on Drawing I. This <br />developing meander is also e~~dent in the channel profile shown in Drawing 2-2. Bank protection is <br />designed to extended upstream along this developing meander to prevent the future migration of this <br />meander from threatening either the rock veins installed downstream or the railroad embanlanenC. <br />The width of the normal flow channel at Section 4 appears to be about 50 feet. The meander is not <br />well developed so the radius of curvature now appears to be somewhat greater than 115 feet. Given <br />these dimensions it is appropriate to continue the average rock vein length of 13 feet and average <br />spacing of 30 feet that was developed for the target meander segment and to make field adjustments in <br />spacing based on the observations by the field engineer during construction. <br />Using an average spacing of 30 feet, 22 rack veins would be sufficient to stabilize the meander bend <br />that is threatening the railroad embankment and the segment upstream that could potentially threaten <br />• the railroad embankment. At a 50 foot spacing, only 14 rock veins would be needed. However, the <br />more distant spacing would increase the likelihood that stream bank toe stabilization would also be <br />required. <br />Since the rock vein length, L, is the distance the rock vein extends into the channel as shown in Figure <br />2-1, the actual vein length (AVI.) needed for volume calculations is actually longer and can be <br />determined as: <br />AVL = L/cos(45~ <br />For a rock vein length of 13 feet, the AVI, is 18 feet. An average AVL of 18 feet and average <br />spacing of 30 feet was used to determine the required volume and tonnage of rock needed for <br />construction as described in Section 2.5. This should result in a slightly lazger volume of rock than <br />may be required. However, the conservative volume estimate is appropriate if a closer spacing is <br />deemed appropriate based on observations during construction. Also, any excess rock material <br />remaining following construction of the rock veins and smaller rock fragments that are not used in the <br />L J <br />N IA F~lenvnc EmpveDesi~doc 1~ 07/30/99 <br />