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' Rimrock Mine Sediment Pond Certification The site inspection was conducted on May 9, 1998. It wa a clear day of 65 degree temperature and it had not rained in the previous few da s. The pond contained .approximately 1.5 feet of clear water, which was wey elow the principal spillway pipe. Engleville Gulch was flowing approximately 0.8-1.2 gallons per minute. The pond is to be left as a permanent impoundment for use in the grazing operation. The following items were checked to see if they coincided with the design shown in the mine permit application. I, Gieg Lewicki, did the pond design in March of 1990. 1) Constructed Elevations: The elevations listed below were checked with a precision level and stadia rod: -Dewatering pipe inlet -Dewatering pipe outlet -Top of Dam -Bottom of Emergency Spillway -Toe of Dam (outside and inside) -Bottom of Pond -A number of points within the pond All elevations were found to be acceptable. The inlet to the principal spillway was placed at a slightly higher elevation to allow more sediment storage. The 10 year - 24 hour runoff storage was still present above the principal spillway. 2) Width of Emergency Spillway Design: 12 feet. Measured: 12.2 feet. 3) Depth of Emergency Spillway Design: 1.55 feet. Measured: 1.60 feet. The spillway showed nb evidence of flow or any signs of erosion or other instability. 4) Width of top of Dam Design: 10 ft. Measured: 10.2 ft - 10.6 feet. 5) Principal S iIR~X Design: 4.0" pipe placed in compacted embankment. Measured: 4" steel pipe placed in compacted embankment. Extensions on this pipe were added to both sides so that the embankment could be widened. Some black, plastic hose was also present near the spillway at the time of the inspection but was not functional. The principal spil]way pipe was completely free of debris and was functional during the site visit.