REP01431

• Permit No: C1980007
• IBM Index Class Name: Report
• Doc Date: 5/5/1995
• Doc Name: 1994 ANNUAL HYDROLOGY REPORT
• Annual Report Year: 1994
• Permit Index Doc Type: HYDROLOGY REPORT
• Media Type: D
• Archive: No

•

EXECUTIVE SUMMARY
This Annual Hydrologic Report (AHR} is
the thirteenth annual report submitted for the
West Elk Mine (formerly the Mt. Gunnison
No. 1 Mine) and covers the period from
1 October 1993 through 30 September 1994
(Water Year 1994). The report describes
and interprets hydrologic monitoring data
collected at the West Elk Mine during water
year 1994 and assesses hydrologic impacts.
The report is divided into two sections. The
first section describes monitoring activities
for Water Year 1994. The second section
interprets the hydrologic data collected
during the year and relates this information
to mining and reclamation activities at West
Elk to assess the impacts, if any, on the
hydrologic balance. This section also ad-
dresses hydrologic impacts that might be
expected to occur during Water Year 1995.
Data from Colorado State University
indicates that WY 1994 precipitation within
the North Fork of the Gunnison River
Valley was 85% of the 1961-1990 average.
Peak flows from snowmelt were observed
between mid-May and mid-June, with earlier
peaks in the smaller drainages.
MCC completed construction on MB-2R and
MB-3 in early 1994. Both ponds were lined
with ageotextile/clay liner. MB-1 was
cleaned and ageotextile/clay liner was also
installed later in 1994. Mine water discharge
was directed to MB-2-R or to MB-1. No
water was discharged from the Sylvester
Gulch underground sump nor from Portal
No. 5. Discharged water had no measurable
effect on the quality of the North Fork of
the Gunnison River.
Imported water during Water Year 1994 was
166.2 acre feet. The volume of water
discharged from the underground workings
R1.210/IOA/OS/OS/95(8~04am)
1
in 1994 was approximately 79 acre feet.
With the development mining under lone
Pine Gulch, areas being mined during Water
Year 1994 were somewhat wetter than
during 1993.
The cycling mechanism on the aerators at
the water treatment plant malfunctioned in
May, resulting in brief excursions of TSS
and BOD at Discharge Point 007A. Repair
of the mechanism resulted in compliant
discharges for the remainder of the year.
An extensive baseline monitoring data base
has been developed for the West Elk Mine.
Operational monitoring started in August
1981 with commencement of construction
activities at West Elk. Completion of one
year of Jumbo Mountain baseline data
collection occurred in Water Year 1994.
This effort involved monitoring twenty
springs and ponds, one surface water site
and one deep well.
Several deep bedrock wells exhibited
changes during Water Year 1994. The
historically dry E-seam well, SOM-23-H-2
had excessive casing moisture during the
three site visits, precluding water level
measurements. It is located one mile south
of any mining activity. Water levels in
SOM-2-H, an F-seam well, also located
south of any mining, dropped 20'. A B-
seam well, SOM-C-72-H was undermined.
Activities at the Lower Refuse Pile had an
insignificant effect on surface or
groundwater quality outside the permit area.
Underground mining activities did not
produce any significant effects on springs or
surface water monitoring stations during
water year 1994.