2021-05-06_REPORT - C1981044

• Permit No: C1981044
• IBM Index Class Name: Report
• Doc Date: 5/6/2021
• Doc Name: Annual Hydrology Report Adequacy Review
• From: DRMS
• To: Twenty Mile Coal, LLC
• Annual Report Year: 2019
• Permit Index Doc Type: Hydrology Report
• Email Name: RAR
• Email Name: JLE
• Media Type: D
• Archive: No

The Williams Fork Mines are located on Segment 13b of the Lower
Yampa/Green River Sub-basin of the Lower Colorado River Basin.
CWQCC lists numeric standards for Segment 13b in its regulation
37. The permitee monitors water in the Williams Fork River at a
site upstream of the mine (WF1), and a site downstream from the
9. Instream CWQCC mine (WF2).
Numeric Regulations 31 Data over time from the upstream site indicate the Williams Fork
Standards and 37 River naturally exceeds the numeric standard for iron frequently,
and occasionally lead and manganese standards.
Comparisons of the upstream and downstream data indicate mining
and reclamation operations at the Williams Fork Mines do not cause
the exceedances.
10. Interim CWQCC Not reviewed
Narrative
Standard for regulation
41.S.C.6
Ground Water
MCM monitors the Williams Fork river upstream of the mine site at
monitoring station WF 1 and downstream of the mine site at WF2.
These sites were monitored in accordance with the approved
sampling plan. Additional monitored surface water sites comprise
mine discharge points(NPDES 9003 and#024) and spoil spring
1SP(NPDES 9022).
11. Surface water Exhibit 29; MCM appears to be sampling the surface water NPDES discharge
monitoring CDRMS mining sampling permit C-1981-
monitoring sites in accordance with their permit.
frequency. 044 Terminology throughout the AHR, and DMR's for sample sites is
confusing because of inconsistent use of various terms. Sometimes
NPDES outfall is used,other times station name is used. Please in
the future use consistent terminology between water quality permit,
DMRs,Williams Fork monitoring location map and Williams Fork
Permit.
12. Surface water Exhibit 29 All required parameters appeared to be sampled.
required CDRMS mining
parameters permit C-1981-
sampled. 044
13. Prevention of Surface water features in the permit area consist of the Williams
impacts to Fork and Yampa Rivers. The postmining land uses of
surface water CDRMS rangeland/wildlife,pastureland and cropland can be expected to use
that adversely regulation water for watering of wildlife and livestock. Mining and
impact the 4.05.1(2) reclamation operations at the Williams Fork Mines do not appear to
postmining land have impaired surface water for these uses.
use.
14. Pond Report CDRMS All filing dates do not appear to have been met. The Division
filing frequency. regulation received only the Q3 Sediment Pond Inspection for 2019.
4.05.9(17)
15. Timely filing of CDRMS Inadequate, at a minimum a note to DRMS of no discharge is
pond reports regulation 4.05. required.
9(17)
16. Pond report CDRMS The sediment ponds associated with Williams Fork Mine in 2019
content regulation 4.05. comprise 5P1, 5P2, 5P3 (outfall 007); 5P5, 596, 5P7 (outfall 003);
9(17) 9AP1 (018); 9AP2 (019); 9AP3 (020; 9AP4 (021); 9P1 (024),
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