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access road flattens near the intersection of Cedar Heights Drive. .Conversations with the guard house attendant indicated that runoff from basins HR-6 and HR-7 causes erosion damage and sedimentation on a fairly frequent basis. Eventually the sediments carried by the runoff are deposited in the Black Canyon Drainageway via the 5430 inch culvert. Erosion of the natural Swale downstream of the propose3 HR-6 culvert has caused sediment to be deposited within the Cedar Heights Drive street section. The runoff and sediments originating within basin HR-6 and the natural Swale are eventually deposited near the existing 24-inch culvert under Cedar Heights Drive approximately 400 feet south of the proposed culvert "A" identified in the Obering Wurth report. Sediment mainly consisting of rock chips oaring in size from 1/4- inch to 1/2-inch have been deposited along the quarry access road presumably by the operator of the quarry. This material can be found along the natural Swale downstream of the HR-6 basin and along the east side of the quarry access road. This material can also be found at several locations along Cedar Heights Drive. Runoff from the HR-6 basin will continue to carry this material to downstream areas until such time the material is removed or otherwise stabilized. This material has apparently been used to construct a truck ramp in the vicinity of the outfall point of the HR-6 basin. J Review of Alternative Options As a result of the preparation of the Obering wurth HR-6 Synder Quarry CAP and the subsequent review of this report by the MLRD, seven alternative drainage plans have been developed. A discussion of each follows. Option 1: This option consists.of the construction of a 24-inch culvert under the quarry access road at the outfall point of the HR-6 basin. This culvert has the capacity to convey the 5-year flow under the road and into the natural Swale. The overflow (i.e., the flows exceeding the 5-year discharge), are proposed to be conveyed in a roadside ditch aligned along the west side of the quarry access road and outfall to the existing 54/30-inch culvert. The total flow estimated to reach the 54/30-inch culvert in a 100-year event is 108 cubic feet per second (cfs). This exceeds the culvert capacity and would cause flow to overtop the roadway in the vicinity of the guard house. This option is in our opinion unacceptable since no provision for stabilization of the natural swale has been proposed. This concept implies that flow will be diverted from the historic flow path. This option would simply shift the existing concerns to another location. - The roadside Swale proposed for this option would have J 2