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~ • • <br />Memo to Dan Mathews <br />Seneca II-W Comments <br />page 2 <br />The proposed site of Pond 005 is a large, currently active landslide complex. <br />I doubt that this area could be rendered capable of supporting the pond. <br />Unfortunately, few alternative areas present sufficient area to accommodate <br />the needed storage capacity. As one proceeds farther down the drainage the <br />increased source area increases the required pond capacity. Based upon my <br />cursory reconnaissance, I believe it may be necessary to erect multiple ponds <br />to accommodate the sediment capture and storage. A smaller pond could be <br />installed approximately half a mile downslope from the proposed Pond 005 <br />site. It may be possible to utilize an "in-pi t" pond to provide the <br />additional required storage, although this will significantly complicate the <br />operati on of the pi t. <br />Segments of Road G and Road H cross several active landslide depoisits. I <br />concur with Bruce's suggestion that these road segments will need careful <br />design or relocation in order to remain stable throughout the proposed life of <br />the operation. In many cases the location of these roads may be dictated by <br />requirements to achieve required maximum grades. I anticipate that careful <br />design to minimize disturbance of the slope or to retain the structure or <br />excavation may be required, Geotechnical analysis of representative slope <br />segments should be completed by the operator. <br />Tom Wainwright indicated that Peabody Coal has scheduled a site visitation by <br />Ground Engineering, Inc., which assisted the operator in the remedy of the <br />slope stability problems encountered at existing Pond 006. Peabody Coal <br />intends to solicit Ground Engineering to prepare a proposal for the required <br />geotechnical consul tation, <br />I have requested that Harry Ranney photograph the proposed permit expansion <br />area during his June 10/11 aerial reconnaissance flight. Low-altitude <br />stereographic aerial photography should significantly simplify the task of <br />identifying the landslide deposits within the proposed permit expansion area. <br />cc: Bruce Stover <br />Jim Stevens <br />Doc. Igo: 6140E <br />JP/jD <br />