REP11882

• Permit No: C1981044
• IBM Index Class Name: Report
• Doc Date: 4/16/1993
• Doc Name: 1992 AHR Text and water quality data tables
• From: CYPRUS EMPIRE CORP
• To: DMG
• Permit Index Doc Type: Hydrology Report 1992
• Media Type: D
• Archive: No

• The average discharge from the ql Strip Pit in 1992 was 25 gpm.
The discharge from the #1 Strip Pit increased significantly in
1989. This may have been due to seepage from the ditch that
conveys the 7 North Angle discharge. The 7 North Angle discharge
began in January of 1989. However, discharge rates from 1990
through 1992 are considerably lower and within the range observe
during 1982 through 1986. Nevertheless, snowmelt and ditch seepage
both appear to have some influence on the Strip Pit discharge, as
the discharge dropped to just a few gpm from January through May
while the 7 North Angle Well was not discharging with a small peak
in March coinciding with spring runoff.
WATER QUALITY
The summary of the water quality data for the spring is presented
in Tables 34 and 35. A plot of dissolved solids for the N1 Strip
Pit is presented in Figure 29. It indicates that the dissolved
solids level of the discharge has increased from an average of
approximately 900 mg/1 in 1982 and 1983 to almost 1,400 mg/1 in
1986, and then decreased to approximately 1,200 mg/1 since 1987.
PONDS
Sediment ponds did not discharge during 1991. Consequently Table
36, listing water quality monitoring results for the year is not
included.

HYDROLOGIC IMPACTS
No significant unpredicted adverse impacts were detected 1992. The
continued drawdown in the Middle Sandstone unit is determined to be
the most significant impact related to mining operations associated
with Mines 5 and 6. The Probable Hydrologic Consequences section
of the Permit predicted drawdown in the Middle Sandstone unit
associated with mining the F and E coal seams at Mines 5 and 6,
although the extent and magnitude of the drawdown were not
quantified. A worst case evaluation was, however, prepared for the
overlying Twentymile Sandstone.
The drawdown in Middle Sandstone Well TR-4 attributable to the
longwall mining in the E and F seams at a distance of approximately
one mile is determined to be between 50 and 60 feet. This is
comparable to the 60 foot drawdowns projected in the PHC for the
overlying Twentymile Sandstone at a distance of one mile from the
location of mine subsidence. No measurable drawdown has been
observed in the Twentymile Sandstone. The impacts observed in the
Middle Sandstone are comparable to the worst case projections
developed for the Twentymile Sandstone.
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