_INSPECTION - C1982057 ‎(6)‎

• Permit No: C1982057
• 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-1982-057/Seneca II-W Mine MLT
(TRM) has been successful in areas where the channel gradient is more shallow, but that it
did not work as well in steeper reaches. This year, the steeper channels were being
reconstructed with regularly spaced rock check dams, and rock-lined channel segments in
between. The rock being used is an angular, red, heat-altered sedimentary material that has
been mined from nearby lands owned by SCC. Rock was hauled to the site using a fleet of
two articulated rock trucks. Placement of the rock was accomplished using a Hitachi
excavator (Photo 2). In these same drainages, the series of surge ponds, including stock tank
T-27 (Photo 3), were being cleaned out, and the bleeder and emergency spillway structures
maintained (Photo 4).
• At Pond 016, construction of the modifications approved under TR-73 has been essentially
completed (Photos 5 and 6). Mr. Karo said wet material in the former Pond 016A was
mucked out, and replaced with drier material excavated from the cut/slide slope to the north.
Weathered shale comprising the cut slope, which had exhibited instability for a number of
years, was removed from into the hillside, exposing more competent shale beneath. SCC has
"paved" the lower portion of the fresh cut slope with crushed rock (Photo 6). Mr. Karo said
this method has been used at Peabody's AZ mine sites, and it has encouraged the
establishment of shrubs on poor-quality soils. An underdrain with a perforated pipe was
installed beneath the toe of the cut slope, to intercept subsurface flow and carry it beneath
Road J to Pond 016. Road J has been realigned both horizontally and vertically, to
accommodate the modifications made to surface and subsurface drainage. The new road
alignment has been surfaced with crushed rock(Photo 7).
• The cluster of wells that was pinched off by slide motion in previous years continues to
create a seep (Photo 8)in the ditch above Pond 016, due to artesian flow from the wells. Mr.
Karo said that the landowner wishes to retain the flow as-is, as it provides an additional
source of water for his property.
• At the "shrub plot landslide", uphill of former Pond 016A, surface and subsurface drainage
was captured as approved with TR-73, and routed to the south before entering Pond 016.
During construction, SCC was able to locate a point source for the subsurface flow (a spoil
spring?) between the shrub plot and channel PM-2. This spot was excavated, and backfilled
with gravel, to provide a least-resistance flow path to the surface. The surface expression of
the spring is protected with rocks, and the water flows approximately 20 feet downhill into
PM-2 (Photo 9). Mr. Karo commented that elk seem to enjoy the availability of water at the
spring.
Pond 017 Watershed
• Mr. Karo and I visited the Pond 017 Watershed, where repair work on Stock Tank T-25
(Photo 10) and channel PM 1 (Photo 11) had been recently accomplished. Grading work that
had been done on the scarp uphill to the north was visible. T-25 had been cleaned out, and
riprap had been replaced in the channel upstream of the stock tank(Photo 12).
SLIDES and DAMAGE -Rule 4.12:
Pond 016 Slide
• Improvements made to this slide area are incorporated into the Hydrologic Balance section,
above.
Number of Partial Inspection this Fiscal Year: 3
Number of Complete Inspections this Fiscal Year: 1 Page 3 of 12