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• November 14, 1979 • Page 3 f. How will the permanent drop structures be constructed and where will the rip-rap to protect Picadilly Road be obtained? The reclamation plan (Exhibit E) and cost tabulation (Exhibit L) was predicated on the use of steel sheet piling driven to bedrock to construct the permanent drop structures shown in the channels of Murphy Creek and Coal Creek (Exhibit F -Reclamation Plan Map). It is recognized that there will be stream channel erosion into the pit which is formed from excavation of the sand, and it is intended to observe this action as it occurs periodically from surface flows. Although large drop structures are depicted on the reclamation map, it may be necessary to utilize several smaller drop structures in each channel to more effectively contain the scouring actions. The structure located on Murphy Creek will be determined and installed approximately eight years after the operation commences when Tract #3 is excavated (Exhibit C -Mining Plan Map), but it is anticipated that the two structures located on Coal Creek will not be required until after twenty years of operation. The conditions of Picadilly Road and its effect on the channel could change completely in that time period, e. g. abridge crossing structure could be built. At the present time the improved surface of Picadilly Road acts as a dam to the scouring effects of surface flows and must be cleared of sand after each occurrence. If rip-rap is determined to be necessary to protect Picadilly Road, it is anticipated that it will be obtained from broken concrete curbing or from a stone quarry. g. How big will the lake be? Exhibit F -Reclamation Plan Map depicts the affected area as it would appear upon completion of the masonry sand operation under conditions of maximum excavation. The eight exploratory borings drilled on the site and the analyses of the subsurface conditions encountered indicate a deposit of clean mortar sand, making it desirable to excavate to bedrock if possible. The groundwater level in the affected area fluctuates with local recharge and discharge conditions, so that the actual excavation depth which is attainable will not be known until the operation is begun and experience gained on the groundwater fluctuations and their effect on the sand deposits. Although the size of the water surface area will vary as the groundwater Ieve1 fluctuates, it is estimated that a normal pool area of approximately 43 acres will be formed upon completion of the operation. The site will continue to function as an open drainageway, however, and this area will diminish over the years by deposition of sand into the excavation area from upstream flows during periods of flooding. 3) Reclamation Map a. Outline in red where the pond will be. An additional copy of the Reclamation Map is enclosed with the estimated elevation of the lake surface outlined in red.