INSPEC15838

• Permit No: M1980244
• IBM Index Class Name: Inspection
• Doc Name: DMG MINERALS PROGRAM INSPECTION REPORT
• Inspection Date: 10/14/1994
• Media Type: D
• Archive: No

(Page 2)
NINE ID / OR PROSPHCTING ID / M-80-964
INSPECTION DATE 10-14-94 INSPHCTOR'S INITIALS BM
OBSERVATIONS
This was a partial inspection of the leach pad construction area and a follow up on some
items noted in previous inspection reports.
The first area inspected was the lower swale caused by the groin juncture of the south elopes
and toe berm where soil liner material was being compacted. The lower ewale had become too
soft from runoff onto the liner material. Soft liner material had been excavated and stored
just south of the "impromptu sump" (above the toe berm) and other suitable soil liner
material had been placed and was being compacted. Compaction techniques were observed and
it appeared that compaction was successful in this area.
A nuclear moisture/density teat of the liner material in another area of the soil liner for
the pregnant solution pond was observed. Following the one minute reading (which was similar
to other readings taken to verify that specifications were being met), a sample of the liner
material was taken to verify nuclear moisture readings. The hole used for the nuclear
moisture/density teat was filled with bentonite chips and tamped to reseal the soil liner.
The pregnant pond anchor trench (9360 anchor trench) was checked with a measuring tape to
verify soil liner thickness. The soil liner below the anchor trench was found to be ae thin
ae four inches next to the anchor trench in the thalweg of Arequa Gulch. Before the plastic
liner can be installed in this area, the operator must ensure that adequate soil liner
material ie installed and that adequate quality control sampling ie undertaken to verify soil
liner thickness in this area.
The "impromptu sump" standpipe was checked and it was found that water from the sump was
still entering the standpipe and, it was assumed, entering the underdrain since water was not
ponding in the standpipe.
The main northwestern surface water diversion ditch construction was inspected. It appears
that the operator ie salvaging topsoil from this area and excavation of material was
proceeding. .Material ie excavated with trackhoee and loaded into Cat 773 35 ton off road
haul trucks.
The lower Arequa Gulch discharge outlet for this diversion was inspected. Topsoil hoe been
pushed to one aide and not completely salvaged yet in this area. The straw bale sediment
control structure was inspected and appears that water could bypass the structure to the
west. This ie a maintenance item that the operator needs to correct soon.
The pipe outlet to Arequa Gulch just below the old Carlton Mill tailings impoundment was
inspected. Erosion and sedimentation in this area was a subject of a problem noted in the
inspection report of 10/03/94. New straw bales have been put in this area and appear to have
been functioning to control erosion and sedimentation. This area hoe not yet received
archaeological clearance yet eo the balsa cannot be keyed into the natural ground. Some of
these new bale structures have been bypassed to the side and underneath the bales. The water
below these structures in Arequa Gulch was found to exhibit a cloudy appearance. The source
of this cloudy appearance could not be readily determined. The water in the sump below the
toe berm did not appear cloudy and the operator was actively pumping water from this sump to
the outlet in Arequa Gulch. Strategies were discussed to try, without excavation, to make
the straw bale structures work as planned to control erosion and sedimentation. This ie a
maintenance item that the operator needs to pay close attention to since this ie the last
chance to control erosion and sedimentation from the project area before water flows on down
Arequa Gulch. This area will~be checked frequently in upcoming inspections to ensure that
proper attention ie being exercised to maintain these structures.
A meeting was held with the new archaeological consultant, Harcue Grant-Paragon Consulting,
and the type of monitoring that would be done was discussed. In the opinion of Nr. Grant,
only spot checks would be needed at night instead of continuous monitoring of surface
disturbances. This ie acceptable to the Division.
Several soil liner density checks were performed through the geomembrane liner on Panels 70
and 68. The types of testa run were back scatter nuclear density and moisture taste. These
testa were correlated by several checks on sections of the soil liner where 10 inch depth