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CRUSHING AND SCREENING LEVEL FILL: • The stability of the fill which comprises the Crushing and Screening Level will be reduced substantially in the event of unanticipated infiltration. We recommend the following improvements be made to the drainage system in the vicinity of this fill: 1. All flows intended to reach Pipe M should be contained at that point. This would involve re-establishing the original ditch design cross sections up- stream o! the pipe inlet. This is necessary to insure that the storm flows can be channelized end controlled more efficiently downstream. 2. The ditch along the rear of the Crushing and Screening Level should be lined with an impervious material and steepened to a slope of at least 1%. This will prevent infiltration from entering the fill. The entire level should be graded toward the inlet near the middle oP the bench. We recommend a minimum overland slope of 1% to insure that there is a minimal amount of inadvertent ponding. Additionally, we suggest that the entire fill be surfaced with an impervious material which should also be sloped away from all structures. This will minimize infiltration and eliminate the possibility of piping along structural foundations. Geo-Hydro indicates that a surficial failure along the slope of this fill would be the most likely type of slide should any failure occur. This type of failure would have a limited impact on drainage near the slide. Damages, if any occurred, would be limited to pipes passing through the fill. We recommend the immediate • repair or replacement of any pipes damaged by a surficial failure of the fill. SHOP/WAREHOUSE/TIRE SHOP LEVEL: Our principle recommendation for this level is that the existing ditches be re- established and maintained regularly. As these ditches fill with debris and sediment, the normal flow of the ditch is inhibited and water ponds behind the constriction. If the ditch is unlined, infiltration is increased. If the ditch is lined, it is possible to overtop the ditch and saturate unprotected areas outside the ditch. The long pipe passing under this entire level may present problems in the future. Should this pipe become clogged, the backwater produced could saturate the entire fill and reduce the stability. Corrosion of this pipe could result in a situation similar to that of clogging. At the present time, this pipe is operating properly and should continue to do so if properly maintained end inspected.