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REP42468
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REP42468
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Last modified
8/25/2016 12:44:21 AM
Creation date
11/27/2007 9:36:29 AM
Metadata
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Template:
DRMS Permit Index
Permit No
C1982056
IBM Index Class Name
Report
Doc Date
12/11/2001
Doc Name
2ND HALF 1993 FISH CREEK ALLUVIAL VALLEY FLOOR STUDY AREA
Permit Index Doc Type
SUBSIDENCE REPORT
Media Type
D
Archive
No
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subsidence. <br />• Fish Creek cross-sections A through F show the baseline survey <br />versus the latest survey. Cross-sections A, B and F are located <br />outside the subsided area and show the natural changes in the <br />stream channel. As noted on these cross-sections very little <br />change has occurred except for some minor movement of sandbars or <br />gravel bars within the specific sections. <br />Cross-sections C and D show the most subsidence impact, although <br />the there is very little difference between the pre and post <br />subsidence surveys except for the elevation change between the tow <br />surveys. Cross-section C dropped approximately 0.7', while cross- <br />section D dropped approximately 0.5'. Again, the general channel <br />geometry is similar between the pre and post subsidence surveys. <br />Cross-section E exhibited the least amount of impact due to <br />subsidence, and it is difficult to determine if the impact is due <br />to subsidence or the natural channel changes. Given the relatively <br />minor change in elevation difference between the pre and post <br />subsidence survey it does not appear any significant changes <br />occurred on this section. <br />5.0 VEGETATION STUDY <br />The 1992 vegetation survey for Fish Creek AVF was conducted before <br />active mining began near the Alluvial Valley Floor. There was no <br />• significant difference between the subsided portion and the <br />unsubsided portion as shown on the attached table. <br />The 1993 survey was conducted at approximately the same time of <br />year, and the cover numbers were slightly higher. These changes <br />can be attributed to the heavy snowpack and wet spring, not to any <br />subsidence activity. <br />The comparison between the subsided ground (A) and the <br />nonsubsided ground (B), shows no significant change from 1992 to <br />1993. Therefore it would be safe to assume the mining has had no <br />major affect on the vegetation in the AVF. <br />Table 57, Average Number of Species per Transect, shows that there <br />is no significant difference between the area that was subsided and <br />the area not subsided. The average number of total species between <br />the two areas did not differ by more than 1 species. The data does <br />show that Area A has fewer desirable species than Area B, but this <br />occurred both pre and post subsidence. Therefore, it does not <br />appear that the difference can be attributed to subsidence. The <br />1993 data does show an increase in desirable species for both <br />areas. <br />• <br />
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