Laserfiche WebLink
Page 4 of 9 <br />The Division has no further concerns. The November 29, 2011 submittal contained a revised Appendix <br />2.05.3(4) -1 as requested. <br />F) The certified pond cross sections in the Arcadis report in Appendix 2.05.3(4) -1 show that the pond <br />embankment inslopes and outslopes for sediment ponds NHN -002 and NHN -003 are both 2H: 1 V. <br />However, Rule 4.05.9(7)(e) requires that the combination of the inslope and outslope of a pond <br />embankment not be steeper than 5H: 1 V unless a demonstration is provided to show that the steeper <br />slopes will be stable. Please provide such a demonstration for ponds NHN -002 and NI-N -003 or revise <br />the ponds' embankment slopes accordingly. <br />The Division has no further concerns. The pond designs in Appendix 2.05.3(4) -1 were revised <br />appropriately in the submittal dated November 29, 2011. <br />G) The Division requests that clearer and larger scale figures of plan views and cross sections for the three <br />sediment ponds in Appendix 2.05.3(4) -1 be provided. Also, please provide plan views with a contour <br />interval smaller than the current five feet. The current figures do not show enough detail. <br />New Appendix 2.05.3(4) -1 drawings were provided in the November 29, 2011 submittal. <br />However, referring to the existing topographic contours shown on Figure 2: Pond NHN -001 Layout and <br />on Map 2.05.3(4) -1, it appears that a portion of the Overburden Stockpile area to the northeast of the <br />pond will be inundated when the water level in the pond exceeds 5680 feet in elevation. Since the <br />elevation of the principle spillway riser for pond NHN -001 is 5682.5 feet and the elevation of the <br />emergency spillway is 5683.5 feet, inundation of this area is possible. Please ensure that the northeast <br />section of pond NHN -001 is built up and compacted sufficiently so that the pond water cannot inundate <br />the Overburden Stockpile area. The cost for the additional backfilling and grading work in this area will <br />be accounted for in the reclamation cost estimate. <br />H) In the 3' complete paragraph on page 4 of the Arcadis report in Appendix 2.05.3(4) -1, there are two <br />sentences in which it is stated that the primary discharge structure will be a drop inlet. However, the <br />certified pond cross sections in the same report show that the primary discharge structure is a straight, <br />18 inch or larger diameter pipe with a 6 inch diameter gated valve. Please revise this paragraph <br />accordingly. <br />Pond designs were revised in the November 29, 2011 submittal to show primary discharge drop inlets <br />on all three ponds. <br />However, in the same revised appendix, the horizontal cross section drawings for all three proposed <br />sediment ponds show a primary discharge structure that has a 6 inch diameter vertical principle spillway <br />riser connected to a horizontal 18 inch diameter cmp principle pipe. However, Figure 5 in the same <br />appendix shows a picture of a vertical 18 inch diameter cmp pipe, with no smaller diameter vertical riser <br />attached. Please explain this apparent discrepancy and revise if appropriate. Also, there is no notation in <br />the pond design horizontal cross - sections for the gated valve on the 18 inch diameter cmp pipe, which <br />appears to be shown in Figure 5. Please explain and revise, if appropriate. <br />I) The certified pond cross sections in the Arcadis report in Appendix 2.05.3(4) -1 show that the gates on <br />the primary discharge pipe are on the inside of the pond embankment. How does Western Fuels propose <br />to open the discharge gates if the water level is well above the gated valve? <br />Revised text and a digital image were included in Appendix 2.05.3(4) -1 of the November 29, 2011 <br />submittal. In the same revised appendix, the profile drawing for each of the three proposed sediment <br />