2016-09-27_REVISION - C1982056

• Permit No: C1982056
• IBM Index Class Name: Revision
• Doc Date: 9/27/2016
• Doc Name: Adequacy Review Response
• From: DRMS
• To: Twentymile Coal, LLC
• Type & Sequence: TR85
• Email Name: JLE
• Email Name: DIH
• Media Type: D
• Archive: No

Twentymile Coal, LLC.
Page 3
September 27, 2016
10. On proposed revised page 14.4 of Exhibit 14, when site 115 is discharging, TC indicated
additional weekly monitoring of site 69, 115, 1003 and 1005 will be conducted. The paragraph
indicates that flow and electrical conductivity will be monitored at site 69, 115, and 1003 while
only electrical conductivity will be monitored at site 1005. The "Mine Discharge Calculator" on
Table E49-26, needs the flow rate from site 1005 as a required variable. Please revise this page to
indicate flow rate and electrical conductivity will be measured at site 1005 or explain in detail and
revise all applicable mine discharge calculator tables to justify not monitoring flow at this point.
11. The proposed revision indicated site 16 will be monitored and used for the Fish Creek Calculator,
approved Table EX49-25 also indicated data from site 16 will be used. Currently Exhibit 14
indicates site 16A will be used. Please clarify this discrepancy. If site 16Awill be used please
revise this in the narrative proposed for Exhibit 14. If not, please update Table A, Surface Flow
of Exhibit 14 to indicate Site 16 will be monitored when pumping is occurring at Site 109 and
115.
12. Please update Table A, Hydrologic Monitoring Sites and Frequency for Bedrock Groundwater to
include the two new Wadge/Wolf Creek Interburden monitoring wells WC -008B and WC -013A
approved with PR10 and PRl 1.
13. Please update Table A, Hydrologic Monitoring Sites and Frequency for Bedrock Groundwater to
change the site number for the Fish Creek Sandstone monitoring wells as 91M001 and 91M004
as they are currently designated and shown on Map 13A.
14. Please update Table A, Surface Flow April — May to include monitoring site 900A for Foidel
Creek.
15. Please revise Table A, Surface Flow April — May to indicate water quality will be sampled once
in April instead of March for the applicable monitoring sites.
16. Please revise Table A, Surface Flow June — September, to include monitoring site 304 and 900A
for Foidel Creek, site 1002 for Fish Creek, MC -1 and USGS 09243700 for Middle Creek.
17. Proposed Revised Table A, Surface Flow October — March currently is approved for a
monitoring schedule October— February. Please confirm that TC is proposing to update the
monitoring plan for monitor through March and not February.
18. Currently Table A, Surface Flow October — February requires monitoring for SW -13, proposed
revised Table A, Surface Flow October - March indicates that no monitoring will be conducted
at site SW -13. Please revise this to comply with the currently approved plan or provide detailed
justification for elimination of monitoring or this well.