PERMFILE45257

• Permit No: C1980005
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Doc Name: AVF RECONNAISSANCE
• Section_Exhibit Name: TAB 07 APPENDIX 7-7
• Media Type: D
• Archive: No

I

State Reg.
s
As shown quantitatively in Section 7-II and 7-III, "Surface Water Informo-
Lion" and "Probable Hydrological Consequences" respectively, the Sen-
eca II Mine comprises less than .3 percent of the Upper Yampa River
Basin and contributes less than .I percent of the total flow. This would
mean a 1000 fold of dilution once the effluent in Grassy Creek joins the
Yampa. A similar logic was used for Fish Creek which showed effluent
would be insignificant in the make-up of the flow.
In addition, both Grassy Creek and the unnamed tributaries of Fish Creek
are over 2 and 4 miles long respectively, and flow through lands contri-
buting agricultural runoff. From mass balances of total dissolved solids,
it was also shown that there would be significant dilution downstream
from the mine. It was therefore determined that both the Yampa River
and the main stream of Fish Creek were not within the adjacent area of
mining.
•.
In terms of ground water, it was shown in "Probable Hydrologic Consequ-
ences" that movement of a total dissolved solid contaminated plume will •
move very slowy down gradient into the Hayden Syncline. Moving at
worst case o little less than one-half mile from the site in twenty years
while being dispersed. Alluvial ground water will also be affected by
mining. However, cutting laterally across the valley north of the mine
are a series of faults which inhibit discharge of ground water to the
valley alluvium. These faults limit the distance of the mine's affect to
alluvial ground water to the north of the mine (see Exhibit 7-3).
The study area is therefore limited to Grassy Creek, Little Grassy, and
the unnamed tributaries of Fish Creek. Seneca Coals, Ltd. has been
mining along Grassy and Little Grassy Creek for over twelve years.
Mining of the coal is done in what is known as adip-slope, area mining
method. This technique of mining is used because of the steeply dipping
Wadge, Lennox, and Wolf Creek cool seams along the western flank of
the Tow Creek Anticline.
•!
7-7-2
Revised 5/27/81