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~. ~~ <br />Memo -Grassy Gap File <br />-4- <br />April 16, 1997 <br />21, As the drainage submittals were partially prepared to satisfy the <br />Division's concerns associated with NOV C-89-034, it is pertinent to <br />review the status of the issues identified in that NOV. <br />lA, See Question 2 on page 2, above. <br />1B; See Question 1 on page 2, above. If you plan to make this a <br />permanent structure, note that the drainage divide on the Pit 6 <br />upper diversion ditch {6-2) differs from that shown on the map. <br />(See NOV C-89-034). <br />1C. It is not clear whether this ditch was reclaimed in conjunction <br />with reclamation of the shop. Please clarify this situation. <br />1D. This information has been provided. <br />2A. and 2B. These will be eliminated by a positive sedimentology <br />demonstration. <br />2C. The current design of Ditch 5-1 appears to exclude the area <br />disturbed by overburden and topsoil stockpiles. Ditch 5-1 needs to <br />be extended to the west and re-designed to respond to 2C. <br />2D. See question 11 on page 4, above. <br />2E. Accurate designs of Ditch 5-1 will provide sufficient information <br />to respond to this issue. <br />3A, and 3B. The California crossings address these items. <br />4A. The Division believes that significant downcutting was observed at <br />the identified inlets for Ponds 2, 3, 4 and 5/6. This issue was <br />not contested by Rockcastle as shown by their failure to attend the <br />assessment conference and payment of the civil penalty for this <br />violation. ACZ believes that there is no significant erosion on <br />4A-1, 4A-2, 4C-1, 4C-3 and 4D-1 and proposes no mitigative action <br />(October 18, 1990 letter). The abatement called for design <br />calculations. If Rockcastle/ACZ can prove that the velocity at the <br />inlets for a 10-year 24-hour event is non-erosive, then armoring <br />calculations would not be necessary. If not, we expect to see <br />designs and a schedule for construction. <br />46-1 and 48-2, Work on these inlets is not required since the pond is <br />being removed. <br />4C-2 .This inlet is associated with the ditch described in 1C above. <br />5A. The Division is still awaiting responses to the Division's adequacy <br />response date October 23, 1990. Pond specifications for Pond 2 <br />were requested at that time. <br />5B. This issue is no longer pertinent in light of plans to reclaim <br />Pond No. 3. <br />See Question 19 on page 4 above. <br />/ern <br />4806E <br />