2010-10-21_REVISION - C1982057 - Laserfiche WebLink

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PM-1A 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" 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 PM-3 3 1.1 6 in/TRM 2,735 4-10 1-3 9 in/TRM 2,655 PM-3A 3 1.3 Veg 1,450 3-5 2-3 TRM 659 PM-6 3 0.75 Veg/TRM 1,816 3-6 1-2 6 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 - PM-1 is a channel in the southern portion of the disturbance that basically runs east to west and discharges into Pond 017. Channel PM-1 has an as-built length of approximately 1,416 feet and a designed length of approximately 1,528 feet. The channel design specifies a bottom width of 3 feet, an overall depth of 0.7 feet and a lining of either 6 inch riprap or turf reinforcement mat (TRM). The observed channel bottom width was between 6 and 8 feet, its depth was between 3 and 5 feet and its lining was 9- 18 inch riprap and TRM. There is a slight deviation of the lower portion of the as-built channel, as it flows more to the south than the original design by approximately 75 feet. The difference in length (slightly shorter than designed) can probably be attributed to the change in the intersection location of Channel PM-lB, which is the dividing line between channels PM-1 and PM-1 A. There is some minor erosion in the channel bottom and there is some side-cutting along the north side of the channel at the top. There was also some under-cutting of the TRM in places, which has resulted in the channel not having vegetative cover in those locations. There was some erosion at the outfall of stock tank T-25, which has been repaired and armored with TRM. The measured channel profile is the same as the as-built channel profile and deviates only slightly ( approximately 15 feet lower in elevation in the lower 700 feet of the channel) from the approved design, which is probably due to the realignment of the lower portion of the channel. The following chart shows the GPS data for post-mining channel PM-l. GPS Height Northing Easting Z Corr. Correct Z Exh D Elev. Z Diff Exh 20- 5.9 Station 7400.3 4468739.1 309385.5 40.620 7440.928 7440 -0.928 7449 2+25 7446.9 4468779.6 309454.1 40.620 7487.485 7492 4.515 7505 4+86 7492.2 4468812.3 309524.9 40.620 7532.841 7532 -0.841 7536 7+42