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• SURFACE WATER HYDROLOGY <br />Tlie CEC site drainage plan and facilities are presented in Appendix K of the Permit, <br />and can also be found in the technical revision, "Drainage Control Plan II," <br />submitted in June, 1994. Diversion and drainage ditches, and drainage swales that <br />have been constricted along the roads and around the north and east sides of the <br />CEC property presently serve to convey surface water nmoff to Sediment Pond 2. <br />Tlie existing drainage facilities, as well as existing site topographic features, are <br />shown on the Existing Surface Features Map. Total long-term sediment accumulation <br />in Sediment Pond 2 continues to be minimal, despite thirteen years of use. The <br />Dugout Pond is to remain widisturbed at site closure in order to provide a continued <br />wildlife habitat, in accordance with CDMG direction. In 1998, both the "East" and <br />"West" Peruneter Ditches, along with Sediment Pond 2 were also deemed permanent <br />facilities (technical revision no. 32). The permanent drainage facilities for final site <br />reclamation are sl~o~vn on the Reclamation Contour and Drainage Plan Map. <br />Standing water accumulation in the forn~er mining pit, except for surface water runoff <br />that soon evaporates, has been eliminated. The deep eolian sand deposits over the <br />mine site, and the sand's high infiltration characteristic, result in a significant loss of <br />• moisture to "deep percolation" of rainfall during major storm events. <br />CEC implemented a dewatering scheme for Sediment Pond 2 in 1997, in accordance <br />with the revised "Spill Prevention, Control and Countermeasures Plan" for the site. <br />When appropriate, CEC personnel will pump excess runoff water accumulated in thus <br />pond back to the Dugout Pond, which is located about 700 feet slightly upgradient <br />and to the south-southeast on CEC property. The Dugout Pond is designated as a~i <br />on-site permanent impoundment and has an available storage capacity exceeding the <br />total contributing runoff volume associated with a 100-year, 24-hour desi~i storm <br />(refer to "Technical Revision Drainage Control Plan ll," dated January, 1995). A <br />bank of pumps will be used, as needed, to evacuate the accumulated nmoff water in <br />Sediment Pond 2 back to the Dugout Pond within a maximum time frame of 72 hours, <br />thus meeting a reasonable evacuation time period for Sediment Pond 2 dewatering. <br />In this mamrer, CEC can also maurtain a continued lowered pond level in Sediment <br />Pond 2 during prolonged periods of excess rainfall and runoff at the site (similar to <br />that which was experienced during the Spring of 1995). CEC did not have occasion <br />to employ this scheme during 1998. <br /> <br />nHR-t~~s -sa- <br />