2015-07-13_GENERAL DOCUMENTS - C1981014

• Permit No: C1981014
• IBM Index Class Name: General Documents
• Doc Date: 7/13/2015
• Doc Name: Email from Kent Gorham regarding MWNW
• From: Kent Gorham
• To: Rob Zuber
• Permit Index Doc Type: General Correspondence
• Email Name: RDZ
• Email Name: MPB
• Media Type: D
• Archive: No

EFCI Southfield Mine — 2012 Annual Hydrology Report
April 18, 2013
3.0 GROUNDWATER AND SURFACE WATER MONITORING RESULTS
3.1 Groundwater Monitoring Results
Mine Area
In the Mine Area, groundwater occurs in surficial alluvial/colluvial deposits and as water table
conditions in the sequence of sedimentary rocks corresponding to the Vermejo, Raton, and Poison
Creek formations. Due to semi -arid conditions and the limited extent and continuity of the
alluvial/colluvial deposits, these units do not store or transmit appreciable quantities of groundwater
in the general mine area. There is limited lateral or regional continuity of potential water -bearing
units due to variable lithology and significant cross -bedding and inter -bedding within the bedrock
units. As a result, there are no known aquifers in the mine area, and bedrock groundwater
occurrences are limited to isolated units and zones that have sufficient local recharge and
characteristics that allow it to store and transmit water. Therefore, only isolated shallow perched
groundwater zones may develop. Additional "minor" groundwater storage may occur in abandoned
and flooded mine workings, which serve as small collection and storage reservoirs as well as for
origination of fracture flows. Additional supporting information may be found in Section 2.04.7 of
the Southfield permit application.
In the mine area, the approved groundwater monitoring program includes the following monitoring
wells:
Well
MW -16
MW -23
MW -65
MW -NW
Location
E'/2NW'/4, Sec 30
r
E'/2SW'/4, Sec 19
Depth/Completion Zone Geologic Completion Zone
Jack O'Lantern Coal Seam
Red Arrow Coal Seam
Jack O'Lantern Coal Seam
Red Arrow Coal Seam (mine void)
136'/ 106-136'
179' / 149'-179'
W'/2SW'/4, Sec 24 1448' / 968'-988'
W'/2SW'/4, Sec 19 380'/ 360'-380'
Monitoring wells MW -7A, MW -713, MW -8, MW -10, and MW -22 were previously included in the
monitoring program, but have since been mined -through and eliminated from ongoing monitoring.
Of these wells, MW -7A, MW -7B and MW -22 were mined -through by Dorchester Coal Co. prior to
1985. EFCI later mined -through wells MW -8 and MW -10 during approved mining operations.
A former mine dewatering well known as the North Well was originally used to dewater abandoned
mine workings in the Red Arrow Coal Seam north of the main mine entries. EFCI discontinued its
use as a dewatering well in 1994, later removing the pump and associated equipment. In 2003, its
well casing was converted to and approved for use as a monitoring well designated MW -NW.
In Technical Revision 35 (TR -35), the approved groundwater monitoring schedule was reduced
from quarterly to semi-annually and is typically conducted in June and December at the four
monitoring wells. Field measurements and laboratory data for active monitoring wells are
summarized in the following discussions. Field and laboratory data for 2012 are provided in
Appendix A. Measured water levels for all wells are summarized in Table 3, Monitor Well Water
Levels, for years 2000-2012. Previous well water level data for all monitoring wells are
documented in AHR's on file at the Division. All historic water level data are presented graphically
for the four monitoring wells on Figures 1, 2, 3 and 4.
2012 AHR text.doc Page 5