PERMFILE46234

• Permit No: C1994082
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Section_Exhibit Name: TAB 07 HYDROLOGIC DESCRIPTION
• Media Type: D
• Archive: No

Eg = mean basin elevation minus 5,000 per 1,000 feet (tt)
Sg = mean basin slope (ft/ft)
end,
e, b1, b2, b3, and b4 are regression coefficients.
Using this repression model, the mean annual discharge end peek discharges for the 2-, 5-,
10-, 25-, 50-, end 100-year recurrence intervals were predicted for each drainage at the
following locations: 1) 011 tributary et its confluence with Grassy Lreek; 2) Y-1
tributary et its confluence with Sage Creek; 3) T-2 tributary at fts confluence with Sage
Creek; 4) Y-3 tributary et its confluence with Sege Creek; 5) Annend Draw et its
confluence with the wofstger Zeigler Reservoir outlet; 6) Sage Lreek approximately one
mile below Sage Lreek Reservoir; and 7) Grassy Creek at Site YSGFS. Table 7-30 presents
the repression equations end coefficients assigned for each discharge characteristic based
on the northwestern region regression model (Kircher et el., 1985). Table 7.31 shows the
results of the calculations for each drainage. In eLl cases, the annual mean end various
regression model recurrence interval discharges increase with increasing watershed area,
irrespective of mean basin elevations.
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snovmelt. Significant accumulations of snow can be expected to occur in the watersheds
draining the Toast mining area. A very significant portion of the annual runoff to
streamflow is from snovmelt. A sAries of snow surveys were conducted during winter and
early spring, 1980 in a similar watershed at the Seneca II-Y Mine, which is located
approximately two mites west and at comparable elevations to the Yoast Mine. The details
of the snow surveys are described and documented in the Seneca II-Y mining permit
application (Peabody Yestern Coal Company, 1991). The effects of snovmelt are not
strictly limited to the melting of the accumv(ated snowpack. Bank storage, frozen ground,
end saturated coil conditions ell contribute to changing the response of the watersheds to
rainfall events during a portion of the spring season, extending beyond the visible
snovmelt period. For the purposes of this tab, the use of the term snovmelt shall include
runoff responses to rainfall during snovmelt influenced periods following the melting of
the snowpeck.
Streamt low. Thie section presents discussions of ctreamf low data (both instantaneous end
continuous) collected et stream monitoring sites associated with the Yoest Mine (ell site
IDs starting with a Y) and two (site IDs start with a Y) associated with the Seneca f2-Y •
Mine, but located on Sege Creek. The discussions are grouped according to the drainage in -
which the sites have been located. Thus, Sites YgSF3, Y552, YssF 1, wssF3, end wSS4 ere
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