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<br /> <br />Mr, Brent Anderson - 4 - April 24, 1991 <br />76. The contour ditch (No. 5, Figure 1, Attachment 1) is not mapped on the <br />Reclaimed Topography Map. Please map this ditch on a representation of <br />the topography at the site and size it fora T00-year 24-hour event per <br />Rule 4.05.4{2)(b). Revise its orientation as shown on figure 2 of <br />Attachment 1 to avoid a right angled turn to the east as such a sharp <br />angle would probably blow out prematu rely. <br />17. Please provide designs for the rock check dams proposed for the Pit 5 <br />access road ditch (Rule 4.05.3(6)(a)). Provide information on the <br />structure, the size of the rock to be used, its porosity and an analysis <br />of the flow velocities through the drainage. <br />18. The Division would prefer to see Ditches 2-1 and 2-2 reclaimed, but we <br />recognize that paragraph IV (3) of the June 26, 1990 Agreement allows the <br />retention of drainage structures supporting the pond, However, all <br />permanent drainages must be sized to handle the 100-year 24-hour event <br />per Rule 4.05 ,4 (2 )(b ). <br />19, Provide a schedule to install and reclaim to a 3:1 badcslope the area <br />east of Pond 4 this summer per the October 8, 1990 submittal. Document <br />the remaining material balance required to achieve reclamation of Pond 4, <br />. 20. The Reclaimed Topography (1990) and Bond Release Documentation Map <br />utilizes a solid line to designate the pit disturbance boundary for Pits <br />1, 2, 3, 5 and 6, At Pit 4, the solid line also encompasses the shop <br />area and stockpile storage area. Please distinguish between the pit <br />disturbance boundaries and the revegetated areas and include those <br />reclaimed areas where the stockpiles were located in Pits 2/3 and 5 as <br />well as 4. We a]so believe that the northwestern boundary of Pit 3 <br />should extend 350' - 400' further west. <br />V, The Division accepts the Rockcastle submittal for this issue. <br />VI. <br />21. The Division requested topsoil replacement depth sampling to conform the <br />uniform distribution of topsoil at Pit 4 and ensure compliance with the <br />agreement, MLRD sampling of the pit was limited last fall ~ <br />(see inspection report dated October 9, 7990) to six samples over the <br />134 acres. The results did not confirm a uniform distribution. Sample <br />depths ranged from 6" to greater than i4". Sample adequacy calculations <br />to the 90th percent confidence level suggest that a minimum of 32 samples <br />need to be taken to effectively evaluate uniform distribution at the <br />site. This information is necessary for us to adequately review <br />compliance with the Agreement and to make a decision concerning bond <br />reduction based on topsoil placement. <br />• <br />