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the primary factor which initiated the slide was seepage water from the south. The <br />geometry and pond water availability were in-place for a significant period of time, only <br />when seepage developed during the spring was the slide triggered. <br />The slide occurred in a area with an unfavorable bedrock orientation. Seeps in <br />the area were noted previously and several other slides have occurred in the adjacent <br />valleys. Prior to the slide we did not observe any signs of imminent instability at the slide <br />location in our previous site visits. The development of a slide in this area can be due <br />to several factors and small variations in the slope geometry, bedrock dip, dip direction, <br />or seepage conditions can significantly change conditions. The undulations in the <br />bedrock surface make it difficult to predict on a local basis the slopes or slope directions <br />which are potentially least stable, although north facing slopes appear most vulnerable. <br />In our opinion, the topsoil stockpile was not constructed in a location which could have <br />reasonably been predicted as unstable. It is possible that a landslide could have <br />occurred at this location without the presence of the topsoil stockpile. <br />Based upon our observations, we believe earth movements associated with the <br />slide are confined to the visible area of the slide. The northern pond embankment does <br />not show any signs of distress or movement. In our opinion, the stability of the <br />embankment has not been reduced by the slide which has occurred. <br />REPAIR RECOMMENDATIONS <br />Repair of the slide should include removal of the failed soil mass, installation of <br />drainage to collect seepage water, removal of the topsoil stockpiles to reduce slope <br />heights, benching of the base of the excavation and re-filling of the area. Excavation of <br />the slide mass will result in an exposed shelf of soils above the slide which will be in a <br />borderline stability condition. This overhanging slope should be cut back as flat a <br />practical and observed to detect movement during the re-construction process. Access <br />of personnel to areas below this slope should be restricted, or protection provided until <br />filling is almost completed. Following are recommendations for repair of the slide area. <br />1. The topsoil stockpiled should be removed from the area and the slope <br />uphill from the slide area flattened as much as practical. The slide mass <br />should be excavated to the base of the slide. We anticipate this will be at <br />the intersection with the claystone layer, similar to conditions found during <br />previous excavations of the lateral subdrains. We recommend excavating <br />until undisturbed material is encountered and the seepage source is <br />exposed. <br />2. Prior to re-filling of the area, we recommend that the base of the <br />excavation be benched to key the new fill into the layer as much as <br />practical. The benches should consist of a consistent series of steps. <br />After benching, fill can then be placed and compacted to planned grades. <br />3 <br />