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3.6 Suggested Modifications <br />• In any future permit, the lower limit of excavation at Bar D should be raised to be <br />consistent with the limit at other pits. Permission to lower the thalweg by as much as 6 ff <br />has given Baz-D an unfair business advantage by greatly reducing gravel transport to <br />downstream pits; it has also caused unacceptable impacts to the river channel and <br />potential damages for upstream landowners. <br />• The lower limit of excavation should be raised during any one-year extension (from <br />December 1, 2003 to November 30, 2004) to the water level at the time of mining, which <br />could be about 2 to 6 ft above the thalweg. This limit would still allow some mining in <br />the downstream part of the pit. <br />• The operator should develop and implement a plan to limit potential damage to properties <br />Located upstream from the pit, with input from USACE, qualified consultants, and the <br />property owners. <br />• Greg Lewicki has proposed that an unmined buffer zone be established at the pit <br />boundaries to limit impacts to adjacent properties. The buffer width being considered is <br />on the order of 150 ft (Greg Lewicki, oral statement to Mary Gillam, 11/11/03). Such a <br />buffer alone would be completely inadequate for protecting adjacent properties from <br />increased erosion that could result from previous thalweg incision at the Bar-D Pit. <br />• Because of channel migration, some of the east-west sections are now at acute angles to <br />existing channels. Greg Lewicki has suggested that all of the sections be relocated so <br />they aze more neazly perpendiculaz to the trend of the channel belt (oral statement to <br />Mary Gillam, 7/25/03). This change should provide better data in the future (less <br />affected by the geometrical problems mentioned above); however, this change should not <br />be approved unless a plan is implemented to provide continuity and compazability with <br />the 1996-2003 data. These objectives could be achieved by monitoring the old sections <br />for at least two years after the new sections are established. <br />• At least two cross sections should be established near the mouth of Hermosa Creek to <br />document any effects that may result from lowering the channel of the Animas River at <br />or near their junction in the lower part of the Bar D Pit. <br />• At least one complete survey of each section should be provided annually, in both <br />graphic and tabulaz numeric form, in a timely manner. <br />• Indicate "Iook direction" on cross sections, For example by labeling east and west <br />• Previous surveys should be provided in tabulaz numeric form. <br />• Information about the locations and depths of extraction azeas should be provided each <br />yeaz for comparison to mining impacts; it is not cleaz whether the operators have <br />followed the stated plan to rotate annual extraction among different parts of the pit, and <br />whether this strategy has shown merit for reducing erosion. <br />• The "2001 Bank Stabilization and Channel Survey" report says that software is used to <br />interpolate "consistent cross sections" from the survey data. Sugnet Environmental <br />should explain this process and include unadjusted data with its re-evaluation of the <br />quality of its survey data (Sean Moore to Lesley McWhirter, 8/25/03). <br />• The 1995 permit application for Bar-D shows 6 cross sections within the pit (CS-1 to CS- <br />6) but does not mention any survey data. If possible, the current operator should obtain <br />any data for these sites and provide it to USACE. <br />Gillam to Hellige, Nov. 28, 2003 page 7 <br />