2013-07-29_REPORT - C1996083 - Laserfiche WebLink

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Notes for site visit July 29. 2013: Jim Stover and I arrived on site around 1:00 pm and met with Bill Bear. Sunday, July 28, 2013 Bowie recorded an event of 2.2" with a rain gauge at the office level, so the event at the gob pile may have been larger than recorded. A 2.2" event is slightly greater than the 25 -year, 24 -hour event. For comparison, West Elk recorded 2.87" in a 23 hour period, with more than 1.14" of the storm occurring between 1 PM and 4 PM. All Sediment Ponds, other than Pond K, discharged through their emergency spillways during the rainstorm. Neither Bill, nor Jim have ever seen any of the ponds discharge through their emergency spillways. Our first stop was Pond C, which was full of water and prior to our arrival had been discharging over the emergency spillway. The water had dropped about a foot from full pool and had ceased discharging from the emergency spillway. Pond C was being dewatered through a pump. Next, we inspected Pond D, which also had discharged from the emergency spillway prior to our arrival. It was 2 -3 feet below full pool elevation and was being dewatered from the primary spillway. Culvert G3 inlets into Pond D, and had conveyed a substantial amount of sediment into the pond, likely a 3 -5' deep delta. Encouragingly, the culvert had not clogged with the sediment that had been conveyed, it functioned properly, as designed. At the gob pile, there was not much that could be inspected. We were only able to get out of the truck at one spot, and could not walk around very much due to extremely wet conditions. No compaction efforts were taking place while we were on site. Two track hoes were cleaning out ditches and culverts. The ditches overall had functioned according to design. The only areas noted with ponding water were in depressions likely caused by vehicle traffic prior to the rain storm. Riprap had been removed from old Ditch F20 Friday July 26 under sunny, clear and dry conditions. Unfortunately, with the large rain event, there was some erosion where the channel had been. Since that area is part of the expansion area, at this point, it becomes a maintenance issue and will continue to be until the piles are effectively combined. Management of drainage on the pile will continue to be a moving target in the expansion area. A substantial amount of effort goes into maintaining positive drainage on the gob piles. Pond F was still full and was continuing to discharge through the emergency spillway while we were on site. Ditch F4 had eroded during the storm event. Repair will be necessary and will begin next week. As a side note to the intensity of the storm, the Fire Mountain Canal had been drained due to a large mud slide entering into and clogging it. Repair was occurring on the Canal while we were on site. And, the UP was down for two days following the storm due to mud covering the rails. This truly was a historic event. At Gob Pile #3, water was still flowing in Ditch J9 -2, and discharging into Ditch J3. Pond J was full of water and still discharging through the emergency spillway. The photos of the upper diversion ditches were taken by the surveyor since it was too wet to walk while we were on site. By Wednesday, when the photos were taken, the ditch had already been cleaned out. I will walk this ditch section during the next on -site visit, it appears the outlet end may have eroded and may require some riprap. Carl Conner surveyed the rock wall near West Diversion Ditch #1 on Wednesday July 31.