GENERAL39774

• Permit No: C1994082
• IBM Index Class Name: General Documents
• Doc Date: 8/3/2005
• Doc Name: Proposed Decision & Findings of Compliance for RN2
• Permit Index Doc Type: Findings
• Media Type: D
• Archive: No

Seneca Coal Company has devised a water monitoring plan that will enable
the Division to determine what, if any, impacts the operation will have on the
prevailing hydrologic balance. The plan is described in detail in Tab 15 ofthe
permit application, and summazized briefly in tables 1-4 in this document.
1. The applicant will conduct monitoring of ground water in a manner
approved by the Division. The ground water monitoring plan is listed
in Tables 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(2)).
F. Probable Hydrologic Consequences
Probable hydrologic consequences of the proposed Yoast mining operations
are discussed in Tab 17 of the permit 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 Tab 17 of the PAP.
The Theis equation, which was also used to predict drawdowns, consistently
predicted higher discharges for each aquifer with the 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, and
745 for the Wolf Creek Overburden, and 499 for the Wolf Creek Coal.
Variability in aquifer chazacteristics in the Grassy Creek and Sage Creek
drainages cause variation in the predicted drawdowns. The radial distance to
Yoast Mine 25 August 3, 2005