_INSPECTION - C1982057 (50) - Laserfiche WebLink

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September 21,2010 C-1982-057/Seneca II-W Mine JRS Additionally, each as-built channel's width, depth and lining were compared with the approved designs contained in Tab 20,Exhibit 20-1. Finally,each channel's as-built location was compared with its approved location, as shown on Exhibit 20-2,approved with TR-59(engineer certified 28 August 2007), as these are the locations that correspond to the design profiles in currently approved Exhibit 20-5.9. -The permanent drainage channel design locations were field fit to correspond with the as-built post-mining topography. While there are some variations in the location of the channels,they are all constructed as designed and appear to be functioning as designed. See each individual channel description below for more detail. The location of the drainage channels along with the Division's elevation and channel construction observation points are shown on Inspection Map 2. The following chart shows the design requirements(D)versus the as-built measurements(M)for the permanent,post-mining drainage channels. Channel D width D depth D lining D length M width M depth M lining M length PM-1 3 0.7 6 inch 1,528 6-8 3-5 9-18 inch 1,416 PM-lA 3 0.8 Veg 1,616 5-8 2-4 9 inch 1,504 PM-113 3 0.9 Veg/TRM 1,931 2-7 2-5 TRM 1,656 PM-1C 3 0.8 TRM 376 4-6 3-5- TRM 501 PM-2A 3 1.25 6 inch 2,680 3-10 1-3 9-12 inch 2,730 PM-213 3 1.1 TRM 1,578 3-15 1-3 TRM 2,170 PM-2C 3 0.85 9 inch 1,500 PM-2D 3 1.2 6 inch 1,513 6-15 1-2 6-9 inch 1,680 PM-2E 3 0.6 6 inch 509 7-20 1-2 4-18 inch 497 9 PM-3 3 1.1 6 in/TRM 2,735 4-10 1-3 in/TRM 2,655 PM-3A 3 1.3 Veg 1,450 3-5 2-3 TRM 659 6 PM-6 3 0.75 Veg/TRM 1,816 3-6 1-2 in/TRM 1,162 D=Channel designs from Tab 20,Attachment 20-1—Post-mining Drainage Channel Design M=Measured and observed channel construction from SL-03 inspection Note: All width,depth and length measurements are in FEET;All width measurements are channel bottom width. -PM-1 is a channel in the southern portion of the disturbance that flows into Pond 017. The channel has been built to blend in with the regraded topography; there is a deviation of the lower portion of the as-built channel, as it flows more to the south than the original design. The difference in length(slightly shorter than designed)can probably be attributed to the change in the intersection location of Channel PM-1B,which is the dividing line between channels PM-1 and PM-1 A. There is some minor erosion in the channel bottom, some side-cutting along the north side of the channel at the top and some under-cutting of the TRM in places, resulting in little vegetative cover in those locations. Erosion at the outfall of stock tank T-25 was repaired and armored with TRM. The measured channel profile is the same as the as-built channel profile with small deviations. Channel PM-1 is stable overall and appears to be functioning as designed. -PM-lA is a channel in the southern portion of the disturbed area and is the upper portion of channel PM-1, above the intercept point with channel PM-1B. The as-built channel PM-lA follows the path of the designed channel Number of Partial Inspection this Fiscal Year: 3 Number of Complete Inspections this Fiscal Year: 2 Page 5 of 18