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_INSPECTION - C1982057 (67)
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_INSPECTION - C1982057 (67)
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Entry Properties
Last modified
11/8/2020 12:02:32 PM
Creation date
6/17/2009 10:06:25 AM
Metadata
Fields
Template:
DRMS Permit Index
Permit No
C1982057
IBM Index Class Name
INSPECTION
Doc Name
Inspection Report
Inspection Date
5/26/2009
Email Name
DTM
Media Type
D
Archive
No
Tags
DRMS Re-OCR
Description:
Signifies Re-OCR Process Performed
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Permanent Channel Erosion <br /> Extensive permanent channel repairs will be necessary in the 016 watershed, which appears to have been <br /> subject to a high intensity rainfall event over the weekend of May 23-26. Numerous channel repair locations are <br /> delineated in this watershed on the 2009 R&G map. Permanent channel repair locations are also properly noted <br /> in various other locations on the map. <br /> The operator had recently initiated rill and gully and channel repairs, but progress was delayed and set back by <br /> the recent rainfall, and associated erosion and muddy conditions. <br /> 005 Gulch "Minimal Disturbance"Drainage Segment <br /> During the inspection, a segment of the 005 drainage channel in the northern part of the permit area was <br /> walked. The channel segment is downstream from the"D" Pit reclaimed spoils, and the specific section <br /> inspected extends from the riprapped outlet of Stock Pond T-20 at the upper end, down to a riprapped segment <br /> just above Stock Pond T-22 at the lower end. The segment was not directly disturbed by mining, but disturbed <br /> area runoff from the reclaimed "D" Pit area flows through the channel to Sediment Pond 005, lower in the <br /> watershed. Stabilization grading and riprap installation has been conducted along certain reaches of the channel <br /> subject to erosive flows in the past. The following excerpt is from a DRMS inspection report dated August 7, <br /> 2007, describing observations made on an inspection of July 31, 2007. <br /> A couple of permit designated"minimal disturbance"native drainage channels were walked <br /> during the inspection...The 005 drainage is deeply incised along most of its length, and <br /> inspection several years ago had noted indications of recent down-cutting in several locations. <br /> At present, the channel appears to be relatively stable, and vegetation is becoming established <br /> along and within the channel along most of its length;likely due to maturing vegetation cover <br /> and reduced runoff from the reclaimed`D"pit portions of the watershed. There is:some <br /> apparently recent minor down-cutting along a 150 foot segment toward the lower end of the <br /> reach, immediately upstream of the point where a riprapped road outlet drain enters the <br /> channel. Stabilization measures may be warranted along this segment prior to sediment <br /> pond removal, if it does not stabilize within the next few years. There is a heavy <br /> infestation of Canada thistle along the drainage within the minimal disturbance area and <br /> spraying is warranted. <br /> Photos#1 through#8, attached to this report, provide comparison of particular channel reaches as they <br /> appeared in July 2007 and in May 2009. The photo sequence progresses in an upstream direction along the <br /> segment. The photos do not provide exactly the same"repeat photography' perspective in each case, but do <br /> depict the same approximate locations. Photos 1 and 2 show the lower reach, immediately upstream of the <br /> riprapped road ditch downdrain; the channel has not cut deeply through this segment since 2007, but there has <br /> been recent scour and the segment does not appear to be healing. Grasses are becoming established along <br /> the banks, where Canada thistle previously dominated. <br /> Photos 3 and 4 are of an incised segment immediately downstream from a pasture fence. There appears to <br /> have been recent bank erosion and sloughing along this reach. Photos 5 and 6 show the channel segment at <br /> the pasture fence crossing. There appears to have been further scour along this reach, and the headcut <br /> associated with the incised segment shown in#3 and#4 appears to have progressed upstream. Photo#7 <br /> depicts an apparently stable, grass lined reach of channel in 2007, which is the site of an active headcut and <br /> side-slope sloughing in 2009(Photo#8). <br /> On the 2009 Rill and Gully map, the operator has indicated a proposed drop structure, to be located in the <br /> approximate location of the active headcutting depicted on Photo#8. The Division concurs that measures are <br /> warranted in this location to prevent progression of the headcut and associated bank slouglhage and erosion <br /> (armored drop structure or a riprapped grade transition zone). Similar measures would appeared to be <br /> warranted for the headcut at the fence crossing, (and other potentially unstable nickpoints, if they occur <br /> along the segment). Low keyed check structures would appear to be warranted along the scoured <br /> section depicted in Photo#2, to reduce flow velocities and minimize further incision. <br /> 5 <br />
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