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T <br />t' <br />~ '~ <br />Breach Point #3 <br />Breach Point #3 on Perimeter Collector Ditch C17 is located 1300 feet west of Pond 007. At this <br />point, the ditch was approximately 190 inches wide by 7" deep. There was a good growth of <br />vegetation in the bottom of the ditch. It is suspected that this portion of the ditch had silted in over <br />the years and lost some capacity. A thick vegetation cover hinders erosion but also decreases <br />water velocity. Putting these two factors together, this portion of the ditch just could not carry the <br />fast impulse of runoff water from the storm. The distance from the ditch to the mine perimeter and <br />5`" Street is approximately 50 feet to the south. The untreated water flowed over 5'h Street and <br />was then intercepted by a poorly maintained ditch (non WFC;s) on the south side of 5~" Street <br />that flowed westward. Evidence showed the runoff water flowed an additional 125 feet to the <br />west, where it entered into a thicket of willows, Cat-Tails and other vegetation. It was estimated <br />the thicket of Willows, grasses and Cat-Tails extended another 200 feet before entering Calamity <br />Draw. It would be safe to assume this vegetation acted as a filter to the untreated water. No <br />significant off site damage was observed. WFC will mitigate this Breach Point #3 by enlarging the <br />ditch to exceed the design dimensions. The same contractor that started work on Breach Point <br />#1 at 7:OOam the next day will do the work here. <br />Breach Point #4 <br />Breach Point #4 on Perimeter Collection Ditch C11 is located approximately 250 feet do North of <br />Pond 008. The ditch dimension at the point of the breach was measured at 200 inches wide by 14 <br />inches deep and had a good vegetation cover. It was observed that Ditch C11 flowed into an 18- <br />inch CMP, which ran down the North West corner of Pond 008 embankment into the pool of the <br />pond. The actual outlet of the pipe could not be seen and it very well could have been obstructed <br />by sediment. The purpose of this culvert was to control erosion from the pond bank. It can be <br />theorized that the outlet controlled pipe was running at its maximum flow and the water in the <br />open channel leading to the culvert started backing up until it found the lowest point to breach, <br />which it did. The runoff water that did not enter into Pond 008 flowed south, down between 2700 <br />Road embankment and Pond 008 embankment, in a dense vegetated channel, until it got to the <br />low point of 2700 Road and flowed across(westward) to an adjoining ranch stock pond. The <br />runoff water entered into this stock pond, and was retained for some period of time before it <br />exited this ponds overflow structure. The discharge water of the stock pond then proceeded <br />another 800 feet across a grass pasture to another ranch stock pond. The discharge water from <br />the second ranch stock pond then flowed approximately 450 feet across another grass pasture to <br />Calamity Draw. Damage from the release of this runoff water is estimated to be minimal. WFC <br />will mitigate this Breach Point #4 by enlarging the entire length of ditch to exceed the design <br />F: \Eng\DATA\WP\dmg\2006\lOjuly06 off site water discharge with photos.doc <br />page 3 <br />