2021-12-02_REPORT - C1981044

• Permit No: C1981044
• IBM Index Class Name: Report
• Doc Date: 12/2/2021
• Doc Name: Annual Hydrology Report Adequacy Review Response
• From: DRMS
• To: Moffat County Mining, LLC
• Annual Report Year: 2020
• Permit Index Doc Type: Hydrology Report
• Email Name: RAR
• Email Name: JLE
• Media Type: D
• Archive: No

Three aquifers exist beneath the site: Trout Creek Sandstone
(No 5 Mine well),Middle Sandstone(Wells TR4,TR7a, 81-01,
83-02, 83-03),and Twenty Mile Sandstone(Wells 259, 84-01,
9 Mine well).
The groundwater monitoring wells were sampled at the
required frequency; quarterly for flow and field parameters,
and annually for the full suite of water quality parameters.
Groundwater well,the No. 5 Mine Well(Trout Creek
Sandstone),had power cut to it in July 2013. The well was
sampled over three quarters and not sampled in 2020 quarter 4
due to a well obstruction.
Table 1- Exhibit Exhibit 29 Table 3A Ex29-8A of the Williams Fork
17. Sampling frequency (pg. ),
29 of CDRMS Permit indicates that YAW 1 2 and 5 or 6 are alluvial wells
of groundwater ,
monitoring wells mining permit C- requiring sampling. These wells do not appear to have been
1981-044 sampled in 2020. These wells are missing from the Table 1B in
the AHR.
The shallow alluvial wells AVF-3, 5, and 6 indicates analyte
sampling occurred on a quarterly basis. According to Ex 29
Table 1 of the permit(. 29-6),the wells only require sampling
on an annual basis(revised in 2000). In the AHR report Table
I shows the wells are to be sampled quarterly.
Well 913F listed on Ex 29 Table 1 (pg. 29-6),of the Williams
Fork Permit,was not monitored. Also,according to Note 5 of
Table 1 the well is required to be sampled on a quarterly basis
if the No. 9 Mine waste rock backfill area has undergone final
grading.
All groundwater monitoring wells that were sampled during
2020 had their respective samples analyzed for the correct
constituents.
In Table 3B of the 2020 AHR the groundwater analyte suite
does not match Ex 29 Table 8 of the permit. Table 3B lists
hydroxide and omits hardness. Hydroxide monitoring and
reporting were removed as part of TR94-23 as indicated on
page Ex 29-4a. Hardness was monitored in 2020.
Although sampled for 2020,according to the Williams Fork
18. Parameters to be Table 1;Exhibit permit sampling of analytes for well 84-01 is not required.
analyzed in 29 of CDRMS DRMS notes that analytes were measured for well 259. Table
groundwater mining permit C- 1B of the AHR indicates annual analyte monitoring.
samples 1981-044
No. 5 Mine Well,has not been sampled since July 2013,
although Ex 29 Table 1 (pg. 29-6),of the Williams Fork Permit
indicates it should be sampled annually.
DRMS notes that analytes were measured for well 259. Table
IB of the AHR indicates annual analyte monitoring.
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