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reservoir. It is estimated that approximately 664,778 cubic yards of material will be required to <br />construct and compact the embankment slope. <br />Dewatering may not be necessary during the installation of the slurry wall. However, it is assumed <br />that during the installation, some water will be present in the pit. In addition, the site currently has <br />exposed water that will need to be pumped out. As a result, it is assumed that dewatering will only <br />be required for one month. <br />Seeding and mulching will be required for the release from the MLRB permit. It was assumed that <br />only the top of the backfilled embankment would need to be seeded and reseeded. It is estimated <br />that approximately 3.4 acres will require seeding. <br />Based on the stated assumptions and our calculations, the cost to install a slurry wall is estimated to <br />be approximately $3,300,000. A summary of the costs associated with the slurry wall option are <br />included as an attachment to this report. <br />OPTION 2: ZONED CLAY LINER <br />Costs associated with the zoned clay liner option are based on a typical clay liner configuration and <br />installation. A typical zoned clay liner cross section is included at the end of this report. According <br />to the operator at the site, a zoned clay liner may take up to 30 years to complete. This is based, in <br />part, on the fact that current mining will only be feasible to a depth of approximately 40 feet below <br />grade. The clay liner will be keyed into the bedrock and utilize the bedrock as the floor of the <br />reservoir. Other options may be available to avoid excavating the additional material present above <br />the bedrock, but those options are more costly than excavating undesired material above the <br />bedrock. It is assumed that the unwanted material will have no resale value and therefore will be <br />viewed as an excavation cost. <br />The clay core material will be keyed into the bedrock. This configuration assumes a 12 foot top <br />width and a 2:1 slope. This configuration also assumes that the mining highwall adjacent to the <br />installed clay core will have a 0.5:1 slope. It is estimated that approximately 567,886 cubic yards of <br />material will be required to construct and compact the clay core. <br />The embankment shell will be placed over the clay core with a 20 foot top width and a 3:1 <br />embankment slope. It is estimated that approximately 378,590 cubic yards of backfill material will <br />be required to construct and compact the embankment slope. <br />Seeding and mulching will be required for the release from the MLRB permit. It was assumed that <br />only the top of the backfilled embankment would need to be seeded and reseeded. It is estimated <br />that approximately 3.4 acres will require seeding. <br />Based on the stated assumptions and our calculations, the cost to install a zoned clay liner is <br />estimated to be approximately $21,100,000. A summary of the costs associated with the zoned clay <br />liner option are included as an attachment to this report. <br />Loloff Pit Engineer's Opinion of Probable Cost I Option 2: Zoned Clay liner <br />2 <br />