GENERAL33508

• Permit No: C1994082
• IBM Index Class Name: General Documents
• Doc Date: 3/6/2001
• Doc Name: PROPOSED DECISION & FINDINGS OF COMPLIANCE FOR RN1
• Permit Index Doc Type: FINDINGS
• Media Type: D
• Archive: No

The applicant will conduct monitoring of ground water in a manner
approved by the Division. The ground water monitoring plan is listed
in "fables 1 and 3 of this document. (4.05.13(1)).
2. The applicant will conduct monitoring of surface water in a manner
approved by the Division. The monitoring plan was submitted under
2.05.6(3)(b)(iv) and is listed in Tables 2 and 4 of this document.
(4.05.13(3)).
F. Probable Hydrologic Consequences
Probable hydrologic consequences of the proposed Yoast mining operations
are discussed in Tab 17 of the pemtit application package. A summary of that
discussion is presented here.
Groundwater
The probable hydrologic consequences to groundwater resulting from coal
extraction at the Yoast Mine include drawdowns to aquifers from pit inflows.
and subsequent pit dewatering and production well pumping as well as
impacts to groundwater quality resulting from flow through mine spoil.
Seneca's predictions of the magnitude of these impacts are discussed below.
Groundwater Inflows to Pits and Associated Drawdowns
The Yoast Mine will intercept the following hydrologic units: the Wadge
Overburden, Wadge Coal, Wolf Creek Overburden, and Wolf Creek Coal.
Seneca Coal Company used two models to predict pit inflows as a result of
mining activities. The models were the McWhorter (1982) method and the
Theis equation, both of which aze described in detail in 7'ab 17 of the PAP.
The Theis equation, which was also used to predict drawdowns, consistently
predicted higher discharges for each aquifer with [he exception of the Wolf
Creek Coal than did the McWhorter method.
The more conservative estimates of pit inflows from each aquifer in cubic
feet per day are 365 for the Wadge Overburden, 160 for the Wadge Coal, 745
for the Wolf Creek Overburden, and 499 for the Wolf Creek Coal. Variability
in aquifer characteristics in the Grassy Creek and Sage Creek drainages cause
variation in the predicted drawdowns. 1'he radial distance to a one foot
drawdown in the Wadge Overburden was predicted to be 401 feet in the
Grassy Creek drainage and 564 feet in the Sage Creek drainage. The one foot
drawdown radius in the Wadge Coal was predicted to be 369 feet in the
Grassy Creek drainage and 468 feet in the Sage Creek drainage. Radial
distances to the one foot drawdowns in the Wolf Creek Overburden and Wolf
Creek Coal in the Sage Creek drainage were predicted to be 452 and 491
Yo>,i Mine ~4, March 6, ?001