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Environmental Consultants, Inc. <br />January 12, 2005 <br />Mr. Tom Kaldenbach <br />Environmental Protection Specialist <br />Colorado Division of Minerals and Geology <br />215 Centennial Building <br /> <br />JAi~ 2 ? 2~~5 <br />Division of Minerals and Gen4onY <br />1313 Sherman Street <br />Denver, CO 80203-2273 <br />RE: Minor Revision 53 -Protected Channel Armoring <br />Chimney Rock Mine (Permit C-81-023) <br />Deaz Mr. Kaldenbach: <br />Kaiser Ventures, LLC hereby submits this Minor Revision that provides the design for the protected <br />channels on the reclaimed areas of the Chimney Rock Mine. This plan provides the methodologies <br />and materials for the channels. The primary considerations will be to armor the channels while <br />minimizing disturbance to existing reclaimed vegetation. Map 8 of the permit identifies the location <br />of the 11 channels to be protected. Slope channels with widths exceeding 1.0 feet will be armored <br />with D50=1.0 foot durable and angular rock. Rock will be placed with a small track loader and hand <br />tools. <br />Attached to this request letter are the Minor Revision Application Form and Protected Channel <br />Information that should be placed in Exhibit 7 of the Permit Document. Rock armoring is sized <br />based on an assumed runoff area for each channel of approximately one acre and a 10-yeaz, 24-hour <br />storm event of 2.25 inches. Maximum runoff (CN=86) is estimated at 1.1 cfs. Riprap sizing curves <br />for steep slopes (Figure 5.3, OSM/TR-82/2) aze extrapolated to determine the D50 rock size of 1.0 <br />foot. Rock is placed to line channel widths exceeding one foot. <br />Should you have questions or need additional information concerning this sampling plan, please do <br />not hesitate to contact Mr. Mike Keegan or let me know. <br />Sincerely, <br />~~ ~ <br />Jerry H. Koblitz <br />Principal <br />Attachments <br />cc Mike Keegan -Kaiser Eagle Mountain <br />5231 South Quebec Street • Greenwood Village, Colorado 80111 <br />Phone (303) 850-0930 • Fax (303) 721-9298 <br />Web Site: www.greystone.as <br />