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u Sept. 20, 1984 Project No. 391.2 Mr. Tim DeWitt Grand County Planning Department Grand County Courthouse 308 Byers Ave. Hot Sulphur Springs, CO 80451 RE: Grand County Gravel Pit #201 MLRD File N M-84-156 engineering pr~e~onals inc. RE~E~UE~ SFp ,~ ~ I,, , MINED LAND Colo. Dept. of NaAMa~lRe~o~rcest OPI Dear Tim: Attached is a copy of our cross sections and calculations for the proposed gravel pit located in Section 8, T1N, R79W. The following information should address your concerns: Excavation and Topsoil Visual inspection of the exposed face and your test pits indicate a topsoil depth on top of the ridge of 24", and a depth of 12" on the face of the ridge; except where previously excavated. It will be necessary to remove topsoil not only from the pit proper, but also from the temporary work area and gravel storage areas in order to provide a firm working area for equipment and to prevent contamination of the stockpiled gravel. Total topsoil volume to be removed and replaced is 12,800 CY. The area you have indicated for topsoil storage is adequate. Our calculations are based upon a 4:1 finished slope for the pit walls, and a 1~ slope on the pit floor, sloping to the county road. Total estimaCed volume of gravel available is 41,500 CY. The amount of topsoil removed will allow you to replace topsoil over the entire disturbed area to an average depth of 18". Drainage Protection Temporary drainage improvements during mining and crushing operations should consist of a simple V ditch graded parallel and adjacent [o the county road to intercept onsite runoff from creating problems on the road, or depositing sediment in the creek. This ditch should be one foot deep, and sufficiently wide to allow equipment to cross easily. The ditch should culminate in a small sedimentation basin on the downhill end (west end). The basin should be approx- 377 FACT Cna1o GIIIIG 9!1'1 P (1 Rnv 6M ~ /`..... ~... /+.. i.. ~..~~ e.ni~r nnnrnn~. rrr.