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1 <br />PoWDERHORN coAL coMPArnr <br />NORTH DECLINE <br />POND NO. 7 <br />As a temporary drainage control measure during the reclamation <br />phase of the North Decline area, Powderhorn designed and <br />installed additional capacity to Pond No. 7. The design is <br />included in Powderhorn's Mining and Reclamation Permit <br />Application on pages ww-26 and ww-27, Appendix ww, Volume 7, <br />Revised 10-7-92. Pond 7 was originally designed as a below grade <br />pond for containment of a 10 year 24 hour storm event with an <br />emergency spillway capable of discharging the peak flow from a 25 <br />year 24 hour event. The pond was designed to use pumping as the <br />primary means of dewatering. <br />The pond enlargement started in the spring of 1982 but was not <br />completed to its final design size until October 23, 1992. <br />Material excavated from the pond was taken from below grade and <br />piled around the south and west edges for ease in backfilling in <br />the future. This material was not compacted as part of an <br />embankment. The attached diagram shows the capacities of the <br />pond as surveyed October 27, 1992. <br />Considering the design, observations during construction, and <br />measured capacity of the pond, I hereby certify that, to the best <br />of my knowledge and belief, this Pond No. 7 meets the pond <br />requirements of rule 4.05.6 of the Regulations of the Colorado <br />Mined Land Reclamation Board for Coal Mining. <br />., <br />M1lei., F4 ~~. <br />!Cy z~~ <br />~. <br />,d ,. i2-v-9Z <br />iL .v' ~ ' <br />oE~ `~ s ~9g2 <br />,..,:,~~ <br />~::. <br />V~WEFHt~. ~. ~- _ . <br />