1977-09-29_PERMIT FILE - M1977315

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1 Projected Land and water Use As indicated earlier in this report, the proposed mining plan contemplates a sequence of pits of several acres in extent. The overburden material would be first removed, and the gravel extracted. The next pit in the sequence would be uncovered by placing the overburden material in the bottom of the previous pit. In this way overburden material will need to be handled only once and pit development would proceed in a "leap frog" manner. In the process of extracting the gravel , it is clear that the volume of space available in the pit that will be occupied by the next pit' s overburden is considerably greater than the volume of overburden to be placed therein. Consequently, it is anticipated that a general lowering of the ground surface within the mined area will result. Although it would be advantageous to bring additional fill material to the site in t order to compensate for the gravel removed, it cannot be E anticipated that such material will always be available when required. Consequently, the mining' plan takes into considera- tion only the material present on the site. As a result of the removal of the gravel and its replace- ment with the overburden material , a pond will be created near the center of the site. Based upon engineering computations of. the material. volumes . involved, it is estimated that the surface area of the pond will be approximately 14 acres . Creation of the pond places an additional burden upon the water supplies of the river system inasmuch as the evaporation rate from an exposed water surface is substantially greater than the water loss through soil moisture evaporation and consump- tion by irrigated crops . As a result,. future land use within the 75-acre parcel will require a substantially reduced acreage devoted to cultivation of an irrigated crop, such as corn. Commensurate with this reduction will be an increase in the -14