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1 <br />Rimrock Mine Sediment Pond Certification <br />The survey and site inspections were conducted on December 7 and <br />22, 1992. <br />The following items were checked to see if they coincided with <br />the design shown in the mine permit application. I, Greg Lewicki, <br />did the pond design in March of 1990. <br />1) Constructed Elevations: The elevations listed below were <br />checked with a precision 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 <br />principal spillway was placed at a slightly higher elevation to <br />allow more sediment storage. The 10 year - 24 hour runoff storage <br />was still present above the principal spillway. <br />2) Width of Emeraencv Spillway Design: 12 feet. Measured: 12.2 <br />feet. <br />3) Depth of Emeraencv Spillway Design: 1.55 feet. Measured: 1.60 <br />feet. <br />4) Width of toa of Dam Design: 10 ft. Measured: 10.2 ft. <br />5) Principal Spillway Design: 4.0" pipe placed in compacted <br />embankment. Measured: 4" steel pipe placed in compacted <br />embankment. <br />