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IRIS <br />MITIGATION AND DESIGN, INC. <br />Environmental Consulting <br />IRIS MITIGATION AND DESIGN, INC. <br />3450 W. 32nd Avenue, 2nd Floor <br />Denver, Colorado 80211 <br />Phone: 720 - 272 -1985 <br />bleisure@irismitigation.com <br />All planted trees shall be 1 " -2" caliper in size and planted shrubs shall be a combination of 50 <br />percent 1 gallon and 50 percent 5 gallon potted stock. Willow stakes shall be harvested on -site <br />or shall be purchased from an approved willow stake source. <br />Following your recommendation, I received direction from the USACE that the following tree <br />replacement ratios would be acceptable and you subsequently concurred that these ratios are <br />acceptable: <br />• Peachleaf willow and plains cottonwood trees greater than 15" in diameter would be <br />mitigated at 3:1 ratio with deciduous trees. <br />• Peachleaf willow and plains cottonwood trees between 6" and 15" in diameter would be <br />mitigated at a 2:1 ratio with deciduous trees or a 4:1 ratio with shrubs. <br />• Peachleaf willow and plains cottonwood trees between less than 6" in diameter would be <br />mitigated at a 1:1 ratio with deciduous trees or a 3:1 ratio with shrubs. <br />• All Russian olive and Siberian elm trees would be mitigated at a 1:1 ratio with <br />cottonwood poles. <br />Impacted trees (except for Russian olive and Siberian elm trees) will be mitigated at a 3:1 ratio if <br />greater than 15" dbh, at a 2:1 ratio if between 6 " -15" dbh, and at a 1:1 ratio if less than 6" dbh. <br />The Schwartzwalder Mine site was re- visited on September 29, 2011, whereby riparian and <br />upland trees that may be impacted during Phase 1 construction activities were re- calculated by <br />dbh. Calculated trees included 15 riparian trees greater than 15" dbh, 52 riparian trees between <br />6 " -15" dbh, and 105 riparian trees less than 6" dbh. The number of riparian trees to be planted at <br />the end of Phase 3 totals a maximum of 252 riparian trees (see Table 1). Riparian trees to be <br />planted will include the following: <br />Schwartzwalder Mine Phase 1 Page 6 October 2011 <br />Response to USFWS Comments <br />