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33 <br />the sedimentation pond in the refuse disposal from area MSHA. The MSHA <br />impoundment I.D. No. is 1211 -CO -9-0039. The sedimentation pond is an earthen <br />rolled dam with an embankment height of 28 feet. Exhibit 20, Refuse Pond Design <br />and Certification, contains all design information and as built certification for this <br />embankment. <br />This embankment (Sediment Pond 008) will control runoff from the refuse disposal <br />area. It has been sized to handle runoff for the life of the refuse disposal area. <br />During a previous permit term, the operator submitted design details for permanent <br />diversion of the Middle Fork of the Purgatoire River. This diversion was necessary <br />to accommodate coal storage and preparation plant operations. The Division <br />approved this permanent diversion and the operator completed the approximately <br />580 -foot diversion in the spring and early summer of 1985. Additional 220 feet of <br />diversion work maybe necessary when plant expansion becomes necessary to meet <br />market demands. Designs will be submitted and approved prior to construction <br />activities, although, the Division has approved the probable hydrologic consequences <br />evaluation of the entire 800 feet during the approval of the initial 580 feet. <br />Exhibit 21, Supporting Information for Permanent Diversion, contains the pertinent <br />design information resulting from the Division's review of the operator's plans and <br />specifications for this permanent diversion. Included in Exhibit 21 are the following <br />design specifications: <br />1. Estimates of a 100 -year storm event at the New Elk Mine, <br />2. Riprap revetment narrative and calculations for a 100 -year storm event, <br />3. Fill calculations for alluvial groundwater movement, <br />4. Final design prior to construction of the permanent diversion, <br />5. Diversion certification and as -built drawings, <br />6. Rip -rap material testing, and <br />7. Annual Surveys for Diversion. <br />In the final design, the Division stipulated that a lesser amount of rip -rap could be <br />placed providing the operator submitted a bond to cover additional rip -rapping <br />should the channel become unstable. In order to evaluate stability the operator <br />committed to an annual survey of the diversion with results submitted to the <br />Division. This survey was completed in February of each year. After 10 year <br />monitoring program, channel stability has remained stable. No further survey of this <br />diversion will be conducted. <br />In order for the operator to maintain Purgatoire River culvert C-89, the operator <br />submitted a revision to the Division during a previous permit term. Following is a <br />summary of this revision: The operator will clean the access road culverts <br />constructed in the Purgatoire River between September 1 through October 15 and <br />February 1 through March 15. The Division will be notified in the event the operator <br />requires emergency cleaning. Normal cleaning will be done during low flow <br />Section 2.05 RN -6 10/17/2016 <br />