2007-07-30_GENERAL DOCUMENTS - C1981041

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] 1.0, average SAR value was 11.7. Soil salvaged from CBA-2 and replaced on CRDA-1 appears to have been somewhat higher quality than the soil available in Soil Stockpile 2, marginally lower quality than than Stockpile 1, and comparable to the soil available from Stockpile 3 (see table below). Sampled Area EC (avgJ SAR (avg] CRDA-1 Cover Soil 11.0 Topsoil Pile l 7.8 11.72 11.54 Topsoil Pile 2 13.3 18.01 Topsoil Pile 3 8.0 14.0 There would appear to have been no appreciable benefit gained from using some combination of available topsoil stockpiles for topdressing, as opposed to use of the CBA- 2 borcow material. (Topsoil Pile 1 was marginally higher quality, but use of Topsoil Pile 1 would have "robbed" the material from the North Portal Reclamation project, and various other areas to be reclaimed). Original permit projections regarding the availability of sufficient material meeting "topsoil" criteria within approved stockpiles and designated borcow areas in the vicinity of the North Portal and CRDA refuse areas were appazently erroneous. RSRDA Roadside borrow area pre-salvage soils data indicated comparatively high quality soils, with all 16 sampled zones meeting subsoil quality criteria for both EC and SAR, and only 4 of the 16 marginally exceeding quality criteria for topsoil. Average values for EC and SAR were well below the permit specified criteria for topsoil. Re-spread sample data verify the generally high quality of the salvaged soils; EC and SAR levels were lower than the topsoil quality threshold in all 1 I samples. Based on review of the information provided, the Division concludes that permit compliance was demonstrated for CRDA-2 subsoil quality, CRDA-1 subsoil quality, and RSRDA subsoil and topsoil quality. Quality of topdressing material was marginal on CRDA-2, and did not meet the suitability criteria on CRDA-l. Should observation and monitoring of vegetative development on the refuse piles indicate problems potentially attributable to high levels of salinity or sodium in the surface soils (e.g. significant bare areas or stunted vegetation our ofchazacter with the native environment), appropriate assessmentand mitigative measures will be required. IV. Sealing of Drilled Holes and Underground Openings The method for sealing portals is depicted in Permit Figure 14-2. The South Mine Portals have been sealed with a 24" thick concrete seal, and will be backfilled with approximately 100 feet of dirt backfill extending out from the concrete seals. An underdrain will be installed in conjunction with final backfilling to drain portal area seepage away from the portal backfill. O[her mine area portal openings were backfilled with a minimum of 25 feet of incombustible backfill. Long term mine discharge (post reclamation) from the Roadside South Mine will be from a gravity discharge pipe installed by angled drilling in the vicinity ofthe North Decline area (Outfa11016); a back-up discharge Permit Revision No. 3 July 30, 2007 Permit No. C-1981-041 Page 35