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Rimrock Mine Sediment Pond Certification <br />The site inspection was conducted on June 30, 2002. It was a sunny warm afrernoon <br />of approximately 90 degree temperature. The pond was dry and there were no signs of <br />recent runoff. Vegetation was brown from the drought. The pond itself was free of any <br />type of problem with stability or erosion. The pond is to be left as a permanent <br />impoundment for use in the grazing operation. <br />The following items were checked to see i€ they coincided with- the design shown in the <br />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) Depth of Emergency Spillway 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: 10 fr. Measured: 10.2 fr - 10.6 feet. <br />5) Principal Spillway Design: 4.0" pipe placed in compacted embankment. Measured: 4" <br />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 site <br />