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Sedimentation Pond Frequency ~ Next Scheduled Survey <br />002 Once Every 9 Years ~ 1998• <br />003 Once Every 5 Yeara 1998• <br />004 Once Every 2 Yeara 3997• <br />008 Onca Every 2 Years 1997* <br />SCC recommends the next survey for all four ponds be completed in 1997 <br />This schedule provides a sediment yield history and gives advance warning to operations <br />personnel when sediment cl ean-ou[ work is required. In accordance with Rule 4.05.6(11)(e), <br />SCC visually inspects each pond a minimum of quarterly each year. During these <br />inapecti ons, any drastic change in sedimentation storage or sudden increase in a sediment <br />delta at the inlet to the pond could be detected which would require mitigation. No <br />sediment clean-out work was conducted during 1995 for the sedimentation ponds at Seneca II <br />Mine. Sediment Ponds 002, 003, 004, and 006 were surveyed in July 1993 Eor sediment <br />de[erminati on. As std ted in the pas[, ponds containing water are very difficult to survey <br />• and obtain a high degree of accuracy. In 1993, Seneca adopted a new approach to sediment <br />surveys- That is, concentrating the survey shots in an area where the most sediment <br />deposition is likely to occur. <br />Rased on the 1993 survey, all sediment ponds have sufficient sediment storage. <br />Additionally, all ponds have been discharging in compliance with the approved NPDES permit <br />effluent limitations. Yearly sediment delivery estimates to the ponds is considerably lees <br />than originally calculated. <br />The following data shows the latest calculated annual sediment delivery and existing <br />capacity. <br />Sediment Survey Results <br /> Pond Year Surveyed Capacity (ac-f t) Avq. Yearly Sediment (ac-f t) <br /> 002 1993 186. 26 0.15 <br /> 003 1993 5. 06 0.003 <br /> 004 1993 8. 28 0.12 <br /> 008 1993 6. 98 0.05 <br /> <br />