2005-01-04_REVISION - M1999120 (2)

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Kate Pickford Division of Minerals and Geology Page 2 of 7 January 3, 2005 The typical process for stockpiling and use of topsoil and overburden in each phase is as follows: a) Within each phase, topsoil and overburden will be stripped from the pit perimeter to construct the slurry wall. Stripped topsoil and overburden will be mixed with fines from the sedimentation ponds and other waste material, if available, that has a high plasticity index (PI) to produce the backfill needed to complete the slurry wall construction. Some overburden will be used to construct the capping to be placed on top of the slurry wall to seal it. b) When slurry wall construction is complete, the perimeter will become the permanent topsoil stockpile area. Overburden will be stored either along the pit edges or within the pit area, and will be used to backfill mined areas as soon as possible. c) Only the required amounts of topsoil and overburden needed for slurry wall construction and reclamation will be kept on site. Excess quantities may be sold and transported off-site as they are generated. d) Stockpiles and berms will be used for reclamation purposes or sold and removed from the site, and their former locations will be top-soiled and seeded per the reclamation plan. 3) Dewatering Trenches, Sedimentation Ponds and Sump Areas: As noted above. the applicant has committed to sealing each mining area with a slurry wall prior to mining below the water table. Consequently, permanent dewatering trenches will not be required around the perimeter of the pit. Temporary dewatering trenches may be constructed within the limits of excavation to dewater the active working faces in areas where silt and clay lens impede drainage. In those cases dewatering trenches will be constructed to move water away from the working face to a temporary sump constructed within the limits of the sealed pit where it will be collected and used to supply the wash plant andlor discharged as per applicant's existing State discharge permit. Both the temporary dewatering trenches and temporary sump areas will be mined out as the pit face advances and/or the pit is excavated down through the sand and gravel zone to bedrock. Trench and sump locations are therefore subject to change as mining progresses. Temporary sedimentation ponds will be constructed within the limits of the pit being actively mined or within a portion of the previously mined pit before reclamation is completed. The size, number and location of these temporary ponds will depend on conditions found to exist during actual mining. Sedimentation settling ponds are used to store the fines from the wash plant until the material is dewatered and consolidated to a point where it can be mechanically handled. The amount of fines generated will vary widely from pit to pit and from year to year. It will depend upon the actual amount of silts and clays encountered in each pit, the percent of sand and gravel sold as a "washed" product during any year versus the amount sold as a "run- of-mine" product, as well as changing economic conditions which will dictate the size fraction which will be classified as waste. Typically, a series of three to five sedimentation ponds will be constructed and placed in active service at a time for a typical 40-acre pit. The effluent from the