_INSPECTION - C1994082 ‎(8)‎

• Permit No: C1994082
• IBM Index Class Name: Inspection
• Doc Name: Inspection Report
• From: DRMS
• To: Roy Karo
• Inspection Date: 9/18/2012
• Email Name: MLT
• Email Name: SB1
• Media Type: D
• Archive: No

September 18,2012 C-1994-082/Yoast Mine MLT
• Channel YPM-6-3 connects Pond 012A with Pond 012. Mr. James said that Pond 012A had
a high-volume discharge earlier in the season, as a result of a significant storm event. The
emergency spillway was utilized in that event, but appeared to be in good condition. We
observed that channel YPM-6-3 was affected by the discharge from 012A. At the outlet for
the primary spillway (an extended corrugated metal pipe), a scour pool had developed, but
the pool was still lined with rock.
• Downstream, the YPM-6-3 channel had been constructed with riprap placed upon a spun or
woven geotextile. In some areas, the riprap had slid from the surface of the fabric under the
force of the water's flow, exposing the geotextile (Photo 4). Mr. James and Mr. Len
commented that the rock appears to slide more easily on a woven fabric than on spun fabric,
and inferred that the coefficient of friction for the spun geotextile is higher than that of the
woven style. In other segments of the channel, it was clear that the water had shifted the rock
and gravel around, but the channel was still essentially riprap-lined (Photo 5).
• At the YPM-6-3 inlet to Pond 012, a wedge of coarse granular material had been deposited
by the storm event. The outlet end of the channel's perforated pipe underdrain was buried
beneath the sediment (Photo 6).
REVEGETATION—Rule 4.15
Vegetative Cover; Timing:
• The cluster of shrub plots immediately southeast of Pond 012 appeared to be healthy, and the
aspen leaves were beginning to change color (Photo 7).
SLIDES and DAMAGE -Rule 4.12:
Pond 012 Landslide
• The slide area located northeast of Pond 012 had passed the 2012 season well, with little to
no adverse impacts due to the precipitation events. Surface flow is directed along the
channel at the bottom of the cut face, from which the unstable weathered shale has been
excavated. The exposed slope appeared to be stable (Photo 8). A large berm of material has
been constructed to separate the slide area from the remainder of the Pond 012 drainage.
Surface flow from the slide area collects into a single short channel which bisects the large
berm and leads to Pond 012. There was evidence (damp soil and surface alkali deposits)in
the short channel (Photo 6)that groundwater seepage continues to occur from the slide area.
Mr. Len pointed out three groundwater monitoring wells that are installed near the eastern
end of the former slide area. Mr. James explained that the Pond 012 slide repairs have not
yet been topsoiled or seeded; SCC is waiting to make sure that the area is stabilized before
commencing those operations.
Pond 013 Slide
• This slide is much larger in size than what I observed during a previous site visit, in July
2009. The cluster of wells above the slide has not been affected by the slide. Mr. James said
that the top of the slide mass has been graded so that surface drainage is directed to either
side. No additional work on the slide is planned at this time.
Number of Partial Inspection this Fiscal Year: 4
Number of Complete Inspections this Fiscal Year: 1 Page 3 of 8