2007-07-30_GENERAL DOCUMENTS - C1981041

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i surrounding areal Upon completion of backfilling and grading operations, topsoil will be`redistributed to a minimum depth of six inches, with the exception of specified areas where topsoilwas not salvaged originally. These areas wily be covered with a suitable amount of plant growth material and amended as necessary. Prior to redistribution of the topsoil, the graded surface will be ripped to relieve compaction and limit surface slippage. P. ~, Based on the results of a study conducted on the Roadside Refuse Disposal Area over a period of 10 years, and associated physical and chemical analysis which demonstrated that requirements of Rule u, 4.15 can be met with less than four feet of cover material, the Division Itas approved a variance from the four foot refuse cover depth requirement of Rule 4.10.4(5). Techni~:al Revision 16, approved by the Division in January, 1994, approved minimum cover replacement depths of 18" on the RSRDA, CRDA-1 and CRDA-3, and a minimum of 24" on CRDA-2. Noti-tonic cover borrow areas, and topsoil and subsoil suitability levels and sampling plans were defined by TR-17, in April, 1994. Reclamation of refuse areas will entail replacement of a minimum 6" tc pdressing layer with SAR of 12 or less and EC of8 or less. The lower 12" to 18" ofcover, as applicable, will have maximum limits of 25 and 15, for SAR and EC, respectively. During adequacy review associated with RN-4 and TR-42, the Division requested that the operator submit soils data, evaluation, and mapping, pertinent to pre-salvage and post-spread sampling conducted in association with 2002 refuse area cover-soiling and top-soiling operations. The requested soils data and mapping were presented in new Appendix 9-%, with narrative evaluation on amended pages 9-4 through 9-%, and amended pages 14-6 through 14-8, and 14-I 1 of the reclamation plan ~, At CRDA-2, subsoil was obtained primarily from excavation within and adjacent to the Coal Creek channel and from construction of the new upper diversion; topsoil was from [ong-term stockpiles. At CRDA-1, the entire cover soil thickness (subsoil and topsoil) was obtained from the CBA-2 borrow area. At the RSRDA, the entire cover soil thickness was obtained from the RSRDA soil borrow area. Soil Stockpile No. 3 was the primary sous. of topsoil used in the North Portal Facilities Area reclamation project. 2002/2003 sample results for areas reclaimed in 2002 are summarized below. CRDA-2 ~~ Data indicates that CRDA-2 subsoil was relatively high quality, with only 1 minor exceedatice of the EC subsoil criteria out of 15 samples (avg. EC=8.0), and no exceedances of the SAR subsoil criteria (avg. SAR=6.9). Texture was silt loam or silty clay loam. Sample data for the 6 inch respread topsoil layer aii; CRDA-2 indicates that, in general, the topsoil was similaz or lower quality growth medium than the subsoil. There were 5 exceedances of the EC topsoil criteria out of 15 samples (avg. EC=%.1), and 4 exceedances of the SAR topsoil criteria (avg. SAR=10.8). CRDA-1 r CRDA-1~ respread soils data reflect sampling of the entire 18 inch cover soil thickness (subsoil and topdressing combined). The material in general [Heels the subsoil criteria (only three of 16 samples exceeded either EC or SAR criteria): However, ] 2 of the ] 6 samples exceeded the topsoil criteria for either or both parameters. Average EC value was Perini[ Revision No. 3 ~ Permit No. C-1981-041 July 30, 2007 ~ '~ Page 34 ~ ~. i i