REP22626

• Permit No: C1980007
• IBM Index Class Name: Report
• Doc Date: 1/13/1997
• Doc Name: 1996 ANNUAL HYDROLOGY REPORT COLORADO PN C-80-006
• Annual Report Year: 1996
• Permit Index Doc Type: HYDROLOGY REPORT
• Media Type: D
• Archive: No

' January 1997 Km Coal Company • 1996 Annual Hydrology Report " CO Permit No. G80~006 ~ 3
3.0 MINE AREA CONFINED GROUND WATER
1
Confined ground water occurs in two water-bearing zones at the mine site: Mine Area Coal
' Aquifer and Mine Area Overburden. The Mine Area Coal Aquifer is monitored at well 79-61.
This well is located just north of the historic Pit 1, along Bush Draw, in the undisturbed coal seam.
The Mine Area Overburden wells are designated 79-1 and 79-2. These wells aze located at the
' north and south ends of the historic 720 Pit, adjacent to what was historically the east crest of the
ptt. See Map 1, Mine Area Monitortng Sites, for general locations.
' Ground water levels were measured and samples taken from these wells during October 1995 and
April 1996, as designated in the Monitoring Plan. The field data from the Confined Ground Water
Wells aze contained in Exhibit A, 1996 Field Data. The individual analyses of samples collected
' are presented in Exhibit B, 1996 Coal Aquifer Water Quality Analyses and Exhibit C, 1996
Overburden Water Quality Analyses. The water quality data are summazized on Table 1, 1996
Ground Water Quality Statistics. Figure 1, Mine Area Aquifer Water Level, shows the relative
' ground water levels for the coal and overburden aquifers over the past five yeazs. The sample
analysis results from the Confined Ground Water wells collected under recommended revised
sampling methods starting in April 1996 vary from previous sampling episodes. The results from
' the revised methodology will be observed through the 1997 sampling year for any new trends.
3.1 MINE AREA COAL AQUIFER
' The mine area coal aquifer well (79-b1) was monitored and sampled in October 1995 and April
1996. Table 1, 1996 Ground Water Quality Statistics, presents the water quality summary for the
year. In general, [he coal aquifer, remains lower in total dissolved solids (TDS) than the
' overburden aquifer, suggesting little interaction between the aquifer systems. For companson
purposes, the mean field and laboratory parameter values for Well 79~i1 over the last five years aze
' presented in Table 2, Historic Mine Area Coal Aquifer Water Quality Data.
Figure 2, EC vs TDS, Well 79-61, presents a comparison of electrical conductance (EC) to TDS
concentrations aver the last five years. The values plotted represent actual levels measured rather
' than a mean value. As seen in Figure 2, EC vs TDS -Well 79-61, the quality of ground water in
the coal aquifer exhibits strong seasonal vaziability, probably related to infiltration of snow melt.
3.2 MINE AREA OVERBURDEN
Table 1, 1996 Ground Water Quality Statistic, also includes a summary of the field and lab resulu
' for the yeaz from wells 79-1 and 79-2.
For comparison purposes, the mean field and laboratory parameter values for the last five years
' aze presented in Tables 3 and 4, Historic Mine Area Overburden Water Quality Data. As shown,
there have been minor fluctuations in concentration values, but there have not been identifiable
trends on a yeazly basis. Figure 3, EC vs TDS, Well 79-1, and Figure 4, EC vs TDS, Well 79-2,
' show comparisons and trends over the past five years.
'~.~ti i eti rmunu.nrnrrvono rrrt TmaMatriz Inc. ' 1? O. Box 774078 'Steamboat Springs, Colorado 80477 "(970J 8796260