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Rimrock Mine Sediment Pond Certi£cation <br />The site inspection was conducted on June 30, 2001 It was a partly cloudy day of 88 <br />degree temperature; normal for this time of year. The pond was dry and there was no <br />evidence of recent rainfall. The pond itself was free of any type of problem with <br />stability or erosion. Engleville Gulch was also dry. The pond is to be left as a <br />permanent impoundment for use in the grazing operation. There was considerable dry <br />fanweed present on the dam and in the surrounding area during the inspection. <br />The following items were checked to see if they coincided with the design shown in <br />the mine permit application. I, Greg Lewicki, did the pond design in March of 1990. <br />1) Constructed Elevations: The elevations listed below were checked with a precision <br />level and stadia rod: <br />-Dewatering pipe inlet <br />-Dewatering pipe outlet <br />-Top of Dam <br />-Bottom of Emergency Spillway <br />-Toe of Dam (outside and inside) <br />-Bottom of Pond <br />-A number of points within the pond <br />All elevations were found to be acceptable. The inlet to the principal spillway was <br />placed at a slightly higher elevation to allow more sediment storage. The 10 year - 24 <br />hour runoff storage was still present above the principal spillway. <br />2) Width of Emergency Spillway Design: 12 feet. Measured: 12.2 feet. <br />3) Denth of Emergenc~Soillway Design: 1.55 feet. Measured: 1.60 feet. The spillway <br />showed no evidence of flow or any signs of erosion or other instability. <br />4) Width of top of Dam Design: ]0 ft. Measured: 10.2 ft - 10.6 feet. <br />5) Principal Spillwav Design: 4.0" pipe placed in compacted embankment. Measured: <br />4" steel pipe placed in compacted embankment. Extensions on this pipe were added to <br />both sides so that the embankment could be widened. Some black plastic hose was also <br />present near the spillway at the time of the inspection but was not functional. The <br />principal spillway pipe was completely free of debris and was functional during the <br />