REP50515 - Laserfiche WebLink

Home Browse Search

I Sedimen[a[i on Pond Frequency Next Scheduled Survey 002 Once Every 5 Years 1999 003 Once Every 5 Years 1999 009 Once Every 2 Yeats 2000 000 Once Every 2 Years 2000 This schedule provides a sediment yield history and gives advance warning to operations personnel uh en sediment clean-out work is required. In accordance with Rule 4.05.6111)1[), SCC visually inspects each pond a minimum of quarterly each year. During these inspections, any drastic change in sedimentation storage or sudden increase in a sediment delta at the inlet to the pond could be detected which would require mitigation. No sediment clean-out cork was conductetl during 1999 for the sedimentation ponds at Seneca iI Mine. Sediment Ponds 002, 003, 004, and 008 were surveyed in July 1993 for sediment determination. As stated in the past, ponds containing water are very dif ti cult to survey and obtain a high degree of accuracy. In ]993, Seneca adopted a new approach [o sediment surveys. That is, • concentrating [he survey sho cs in an area where [he most sediment deposition is likely to occur. Based on [he 1993 survey, all sediment pontls have sufficient sediment storage. Additionally, all ponds have been discharginy in compliance with the approved NPDES permit effluent limi [a Irons. Yearly sediment delivery estimates to the ponds are considerably less than originally calculated. The following da [a shows Che latest ca Lculated annual sediment delivery and exis[i ng capacity. Sedi men[ Survey Results Pond Year Surveyed Capacity lac-fU Avq. Yearl y Sediment lac-ftl 002 1993 186.26 0.15 003 1993 5.06 0.003 U04 1597 8.28 0.12 Uue 1993 Fi. b9 0.05 From [he pas[ history of sedim ent d=1:very [o all of these ponds [here should still be more • that aUequace sediment storage ava: :.,l:e. SrC rid survey ponds U 04 and 008 in 1998, but was unabl e to Lora to the 1'~i evi ous su r:~y :nto una [ion. Based on the infc nnation provided above, 6