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Conclusion. No sediment clean-out work is scheduled during 1991 for the sedimentation <br />• ponds at the Seneca 1I Mine. Sediment surveys are en approximate determination of <br />sediment eceumuletion in the pond. The survey is used to determine measurable differences <br />in pond capacities. Variability of surveys is caused by differing the location of the <br />survey shots from survey to survey end by the surveying rod inadvertently penetrating the <br />muddy pond bottom, thus causing en error in the reading. The 1990 survey of Pond 004 <br />showed en increase in volume over the 7987 survey due to these inevitable inaccuracies. <br />Due to the fact that most of the area above Pond 004 is now reclaimed, a large amount of <br />sediment inflow would not be expected between the 1987 end 1990 surveys. Pond 008 <br />sediment storage volume decreased by 1.0 sere-foot from the 1987 survey. This amount is <br />still less than that predicted (1.8 ac-ft/year). <br />The following schedule will continue to be followed regarding sedimentation surveys: <br />Sedimentation Pond Frequency Next Scheduled Survey <br />002 Once Every 5 Years 1992 <br />003 Once Every 5 Years 1992 <br />004 Once Every 2 Years 1992 <br />• 008 Once Every 2 Years 1992 <br />This schedule will provide a sediment yield history and allow advance warning to <br />operations personnel when sediment clean-out work is required. In accordance with Rule <br />4.05.6(11)(c), Peabody visually inspects each pond a minimum of quarterly each year. <br />During these inspections, any drastic change in sediment storage or sudden increased in a <br />sediment delta at the inlet to the pond Could he detected which would require mitigative <br />action. <br />1 ' <br />~J <br />9 <br />