REP13825

• Permit No: C1980007
• IBM Index Class Name: Report
• Doc Date: 4/8/1991
• Doc Name: 1992 Annual Hydrology Report
• Annual Report Year: 1992
• Permit Index Doc Type: HYDROLOGY REPORT
• Media Type: D
• Archive: No

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the 1991 water year (probably by local subsidence).
In addition, both wells are appazently in contact
with the mine ventilation system.
Mine Water Monitoring
Mine water inflows in areas being actively mined
were mapped during water year 1991. Areas of
previous mine inflows were monitored by oarsion-
al visits. Exhibits II and Ili show ]options of
inflows and estimated amounts of mine inflows in
the "F" seam and "B" seam, respectively. Areas of
standing water are also shown.
During 1991, samples of mine discharges were
taken hom the MB-1, MB-2, and MBS sediment
ponds. They were tested for pH, electrical conduo
tivity, total suspended solids, total dissolved solids,
and total iron. Results of the analyses are shown
on Table 5. The quality of water sampled was good
and posed no problem for direct discharge to a
stream or other surface feature.
The mine water balance, based on actual and
estimated flows, is shown in Table ti. The quantity
of water discharged or pumped from the mine was'_,
approximately 39 awe feet. Water unaccounted for
is lost through seepage and evaporation into the
ventilating air. Both of these losses can be large,
depending on conditions.
"F" Seam
Average flows in the "F" seam were estimated for
the spring runoff season and the low-flow time of
year (Exhibit II). Inflows into previously mined
areas along Sylvester Gulch and near the main
portals continued to be responsive to the spring
runoff season. However, the duration and amount
of inflow were less than in years previous to water
year 1991 because of low precipitation and runoff.
Areas along the Sylvester Gulch Main Mine Fan
entries produceA measured flows ranging hom 0.25
to 0.5 gpm during low flow conditions. Spring
runoff bows ranged hom 3 to 5 gpm. The old
Sylvester Gulch area (entries 14 through 21, main
intakes) produced estimated flows ranging from 0
gpm during low flow conditions to 1 gpm during
spring runoff conditions.
Flows in the main portal area (entries 1 through 5)
were similar to those o[ the 1990 water year. Esti-
mated flows ranged from 0 to 0.25 gpm during low
Oowconditions. Spring runoff conditions produced
flows of 1 to 3 gpm. Entry 1 on the east side of the
main intake hom crosscut 1 to crosscut 7 bad
standing water year•round. Flows in this area were
estimated at 0.0 to 0.5 gpm during low flow condi-
tions and 2 to 5 gpm during the spring runoff.
Entry 9 on the west side of the southwest main
intakes from portal entry 5 to crosscut 7 produced
flows estimated at 0 to 0.75 gpm during low flow
conditions and 0.5 to 1.0 gpm during spring runoff
conditions.
New areas mined in 1991 produced minor damp
and wet areas with no associated measurable flows.
Wet areas occurred in Panels NW1S and NW2S
which were developed hom the 1 Northwest and 2
Northwest Submains. The bleeder in the 1 North-
west Submain continued.
"B" Seam
Small quantities of water (< 1 GPM) were
encountered during development mining in 1991.
Bepuse dripping and water inflow generally
subsided within 24 hours, the water appears to be
contained within fractures and found in association
with roof joints, minor faults, or rock spars. Areas
o[ damp top persisted loplly along the more
pronounced fratture trends.
Water inflows were greatest along the more highly
hactured canes. Initial water inflows were estimat-
ed as high as 20 gpm. After fractures were dewa-
tered, inflows dropped substantially. However, a
few ]options continued to produce water at an
estimated 1 to 3 gpm (Exhibit III). No seasonal
variation in flows was observed.
'=.