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ARCOSA The placement method for these off-spec materials is as follows: Off-spec material is trucked from the plant site in a relatively dry state (15% moisture) at an estimated rate of approximately 50 to 70 tons per day. The material is placed along the contours of the sidewalls of the portion of the quarry that is undergoing contemporaneous reclamation. The material is placed along the sidewall via dozer pushing the solid waste material over the edge of the quarry sidewall allowing the material to slope down the side of the quarry. Since the material is placed within the impervious Pierre Shale Formation, potential leachates are expected be contained to within the quarry. More recently, the placement of off-spec material into the quarry has been completed by end-dumping the materials into the mined-out portion of the quarry. This practice was added to the mine plan after the 2013 floods caused water to pool in the main quarry, which limited the ability for back-fill to be placed along the contours of the quarry walls. The practice of end-dumping off-spec materials directly into the quarry has ceased. Currently, the off-spec materials are being stockpiled at the processing facility until the quarry can be dewatered. Once dewatering is complete, the back-fill material will be recontoured to reclamation specifications and new material will be placed in lifts as originally planned. To verify that leachate from the off-spec material (and in particular the lime scrubber sludge) will not impacted local groundwater conditions, the following considerations are made: 1. As summarized in the Engineering Design and Operations Report prepared by Sergent, Hauskins & Beckwith in 1992 for the Western Aggregates, Inc (former owner) proposed Shale Mine Ash Backfill Project; the Pierre Shale formation hydraulic conductivity ranges from approximately 10-6 cm/s to 10-7 cm/s. The results presented for hydraulic conductivity packer test and laboratory hydraulic conductivity of the Pierre Shale indicate the quarry area consists of very low- permeability material with low potential for migration of water through the formation. a. Table D-1 and Table D-2 present information on insitu and laboratory hydraulic conductivity testing performed on Pierre Shale and Pierre Shale fines. 2. Historic groundwater monitoring wells were used at the site. These groundwater monitoring wells were used previously by Western Aggregates Inc. in the Engineering Design and Operations Report discussed above; however the wells have since been abandoned, decommissioned, or are no longer present or usable. From that report, groundwater was found to be isolated within a seam of sandstone within the Pierre Shale formation. This groundwater was at elevation 5800 a.m.s.l., which is approximately 60 feet below the proposed bottom of quarry elevation. Furthermore, the sandstone lenses within the Pierre Shale formation are discontinuous and small and would not be a reliable source of groundwater. 3. As discussed above, the regional and site-specific geologic information suggest the Pierre Shale formation is approximately 8,000 feet thick in this area. 4. As discussed in Exhibit G, the regional groundwater hydrology indicates the nearest groundwater aquifer is likely contained in the Fox-Hills Formation. This formation has an outcrop close to the affected lands; however the formation dips awau from the Pierre Shale formation at the Site. Given the hydraulic conductivity of the Pierre Shale formation, water quality impairment of the Fox Hills formation from the quarry ponds is unlikely. 5. The alluvial deposits overlaying the Pierre Shale within the quarry area are removed during mining operations. The mining operations are performed in the Pierre Shale formation at lower