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--~. <br />UEPAR fNlu+i OF NATURAL Rf_SOURCES <br />D Ido nle Faseoe Eeecolmq pirn[I O~ <br />MINED LAND RECLAMATION DIVISION <br />DAVID C. SHELTON Director <br />Ric M1artl D Lamm <br />Go.ernor <br />III III III III IIII III <br />December 29, 1982 <br />T0: Dan Mathews <br />FROM: Jerry Zilnpfer ~~~~. <br />RE: Grand Mesa Findings - Backfilling and Grading, Stream Channel <br />Reconstruction <br />Stream Channel Reconstruction <br />The applicant has provided a plan for the reconstruction of an ephemeral <br />stream channel (watershed < 1 sq. mile) through the surface facilities <br />area followng the cessation of mining activities. (See Section <br />2.05.4(2)(cj of the permit application as revised November 30, 1982.) <br />The plan contains some design details. However, additional information <br />is necessary to dete rnline the adequacy of the plan. <br />Stipulation <br />WITHIN 90 DAYS OF THE PERMIT ISSUING, THE APPLICANT SHALL SUBMIT A <br />REVISED STREAM CHANNEL RECONSTRUCTION PLAN TO THE DIVISION FOR <br />REVIEW. IN ADDITION TO THE INFORMATIOIV PREVIOUSLY SUBMITTED, THE <br />STREAM CHANNEL RECUNSTRUCTION PLAN SHALL IDENTIFY THE WIDTH OF THE <br />NATURAL STREAM CHANfJEL DOWNSTREAM OF THE DISTURBANCE, THE MAXIMUM <br />WIDTH OF THE RECUNSTRUCTED CHAIJNEL, THE DEPTH OF THE RECONSTRUCTED <br />CHANNEL, AND THE NATURE OF THE BED AND BANK MATERIAL TO BE USED FOR <br />CHANNEL RECONSTRUCTION. THE APPLICANT SHOULD PROVIDE CALCULATIONS <br />FOR THE DESIGN EVENT ANU FOR FLOW VELOCITIES IN BOTH THE 5 FT. WIDE <br />AND 10 FT. WIDE CHANNEL SEGMENTS. THE APPLICANT SHOULD IDENTIFY <br />STREAM SEGMENTS WHERE RIPRAP OR OTHER EROSION PROTECTION WOULD BE <br />USED. <br />IF RIPRAP IS USED, THE PLAN SHALL INCLUDE A DISCUSSION CONCERNIIJG <br />THE SIZING, GRADATION, AND PLACEh1ENT OF RIPRAP. IN ADDITION, IT <br />SHOULD DISCUSS HOW THE DURABILITY OF THE MATERIAL USED FOk RIPRAP <br />WOULD BE DETERMINED. <br />/mt <br />cc: Jim Pendleton <br />Brian Munson <br />e,c, # as8 <br />423 Cenlcnnial Building, 13 t7 Sherman Slreet Denver, Colorado 80203 Tel (3031 866-3561 <br />