REP47560

• Permit No: C1980007
• IBM Index Class Name: Report
• Doc Date: 5/1/1989
• Doc Name: ANNUAL HYDROLOGY REPORT MT GUNNISON NO 1 MINE WATER YEAR 1988
• Permit Index Doc Type: HYDROLOGY REPORT
• Media Type: D
• Archive: No

•
EXECUTIVE SUMMARY

This annual hydrologic report is the seventh
annual report submitted for the Mt. Gunnison
No. 1 Mine and covers the period from 1 October
1987 through 30 September 1988 (water year
1988). The report describes and interprets hydro-
logic monitoring data collected at the Mt. Gun-
nison No. 1 Mine during water year 1988 and
assesses hydrologic impacts.
discharged from the underground workings in
1988 was 16.8 acre feet versus an estimated
33.8 acre feet in 1987. Areas being mined during
water year 1988 were drier than during 1987.
Precipitation was slightly higher in 1988 than
in 1987. Spring runoff and stream flow rates
reflected this difference.
The report is divided into two sections. The
first section describes monitoring activities for
water year 1988. The second section interprets
the hydrologic data collected during the year and
relates this information to mining and reclamation
activities at Mt. Gunnison to assess the impacts,
if any, on the hydrologic balance. This section
also addresses hydrologic impacts that might be
expected to occur during water year 1989.
An extensive baseline monitoring data base
has been developed for the Mt. Gunnison No. 1
Mine. Operational monitoring started in August
1981 with commencement of construction ac-
tivities at Mt. Gunnison.
Monitoring data for the period 1 October
1987, through 30 September 1988 show no sig-
nificant adverse impacts to the hydrologic balance
from mining activities at the Mt. Gunnison No. 1
Mine.
Mine inflows during water year 1988 were less
than during water year 1987. The volume of water
The quality of mine water sampled in 1988
was good and all discharges were well within
NPDES effluent limitations without treatment.
Mine water discharge in 1988 was from Portal
No. 2 into pond MB-1. No water was discharged
from the Sylvester Gulch underground sump.
Discharged water had no measurable effect on the
quality of the North Fork of the Gunnison River.
Activities at the Lower Refuse Pile also had
no measurable effects on surface or groundwater
quality during water year 1988.
Underground mining activities did no[ pro-
duce asignificant eC(ect on any springs, ground-
water wells, or surface water monitoring stations
during water year 1988.
Water year 1989 is expected to be similar to
1988 with respect to hydrology at the mine. No
significant impacts are expected.
C 1