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INSPEC05755
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INSPEC05755
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Entry Properties
Last modified
8/24/2016 9:01:19 PM
Creation date
11/18/2007 8:23:22 AM
Metadata
Fields
Template:
DRMS Permit Index
Permit No
C1981023
IBM Index Class Name
Inspection
Doc Name
Inspection Report
Inspection Date
9/28/2004
Media Type
D
Archive
No
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bond release area appears suitable for wildlife habitat with Stollsteimer Creek's riparian zone bisecting <br />the area, and pinon/juniper cover on adjacent hillsides. <br />SLIDES AND DAMAGE <br />Gully erosion has occurred at the following four locations: 1) on the hil(slope on the southwest corner <br />of East Pit, 2) near the middle of the west slope of east pit, downslope from the permanent road, 3) <br />near the middle of the east slope of east pit, and 4) in the Revision 1 area upslope from culvert CS (a <br />black plastic pipe). The attached photos show the deepest gullies. Most gullies range between 1 and 2 <br />feet deep, and 20 to 100 fr long. The total azea covered by gullies in the bond release area is estimated <br />to be I.5 acres. The gullies originate as headcuts on the steeper parts of open hillslopes, and terminate <br />either at a ditch at the bottom of a slope or where a slope flattens out. Spoil backfill is exposed in the <br />gullies. The gullies have steep walls that appear to be fresh exposures, as they do not have vegetation <br />growing on them. The Division is evaluating the need for implementing additional erosion control <br />measures in the East Pit area on the slope immediately southeast of the drop structure. Other than the <br />four gullied areas, the reclaimed lands appeared erosionally stable. <br />Sediment fans exist at two locations below gullied hillslopes on the west side of the East Pit area. The <br />lazgest fan covers approximately 1,000 square feet north of the surface facilities/parking area. The fan <br />is on land that underwent final bond release in SL-4. Although the site was dry during the inspection, <br />the apparent source of this fan was discharge from the double-culvert drop structure immediately north <br />of the surface facilities/parking area, in the bond release area currently being reviewed. A smaller fan <br />covers a few hundred square feet, approximately 500 Feet north of the large fan, also in SL-4 bond <br />release area with an apparent source in the SL-5 bond release area. <br />Rills less than 9 inches deep are widespread on many of the hillslopes in the bond release area. Many <br />of the rills appear to have vegetation growing in them, indicating rill formation some time ago, and do <br />not appeaz to indicate excessive erosion. <br />Amos Martinez mentioned during the inspection that the larger sediment fan probably formed during <br />two recent rainstorms. I checked online rainfall records and the Pagosa Sun newspaper and found that <br />heavy rain fell in Archuleta County September 19-21, one week before this inspection. The newspaper <br />noted the rains were spawned by remnants of Hurricane Javier. Rain gauges nearest the mine showed <br />1.06 inch of rainfall at Durango on September 19, and 6.4 inches of rainfall on Wolf Creek Pass on <br />September 19-21. The USGS gauge in the Piedra River neaz Arboles showed discharge increased from <br />60 cfs on September 19 to 1800 cfs on September 20 and 21, and then receded. Based on the timing <br />and appearance of the gullies, and some of the rills, the erosion appears to have been caused by the <br />rainfalls on September 19-21, 2004. <br />No structural stability problems were evident on reclaimed slopes. Tension cracks were not found in <br />the upper parts of slopes; bulges were not evident at the bottoms of slopes. <br />At vazious times during the inspection, Amos Martinez expressed dissatisfaction with reclamation <br />work that has been done on the site. I understood his main concerns to be: <br />1) Gullying on the slope immediately southeast of the drop structure would have been prevented if <br />that slope had been shaped differently during initial reclamation. <br />5 <br />
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