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iii iiiiiiiiniuiii Mathews, Dan 999 From: Mathews, Dan Sent: Monday, December 11, 2000 2:52 PM To: Berry, David; Boulay, Mike Subject: roadside TR-35 I have enclosed a draft TR-35 PAR for your consideration. I did not perform a detailed review of the hydrologic designs (that not being my forte), but I did try to make sure that the plan appeared to be functional, internally consistent and in compliance with regs. I asked Mike to look at a couple critical ditch sizing and riprap designs, and the proposed sed pond at North Portal, but to not spend the time to do a comprehensive review of sedcad demos and designs. Mike says that would take another couple days most likely, if he were to do such comprehensive review. Should we take the time to have Mike do that detailed review or not? One issue I would ask both of you to ponder: In the original design, the RDRDA upper diversion would have flowed to the north, and exited the disturbed area via the conveyor tube beneath I-70 (see Exhibit 6C). It was determined that the conveyor tube gradient was such that this option was not feasible. Stover's proposed solution in the revision is to route the RSRDA upland diversion to the South, which entails a very steep riprap segment along the south end of the pile. The ditch would be largely on refuse, because adjacent undisturbed land is a sandstone cliff face. The ditch is literally between "a rock and a refuse pile" as Boulay points out. The only alternative would be to run the upland ditch to the north, and wrap it around the refuse pile in a big circle. Which probably wouldn't make much sense. Mike says the riprap design for the steep south end ditch looks good, so I'm thinking that is probably the best approach, but I wanted to know your thoughts. As we discussed, Jim Stark will need to do cost estimate for both TR-35 and TR-33 (minewater discharge plan). The primary elements of TR-35 affecting the cost estimate would be excavation and haulage of material from the new borrow area, reclamation of the borrow area, and installation of french drains at the South Portals. Riprap sizing for various ditches may have changed, alghough I believe the extent of ditch segments with riprap is pretty much the same. Johanna does have a complete packet of amended pages and Exhibits associated with TR-32 Coal Creek channel riprap designs and CRDA-2 upper diversion reclamation changes which Stark will need to use. PS. Mike, can you give me the appropriate language regarding North Portal sed pond design deficiency for insertion in PAR Item 2? I didn't get that done. Thanks. T l:__.! iazooornas P~R,doc