2020-12-21_PERMIT FILE - C1981010A ‎(11)‎

• Permit No: C1981010A
• IBM Index Class Name: Permit File
• Doc Date: 12/21/2020
• Doc Name: pages 2-425 to 2-478
• Section_Exhibit Name: 2.7 Hydrology Part 2
• Media Type: D
• Archive: Yes

TDS at site S-3 ranges between 286 and 2080 mg/I.The concentrations of TDS plotted versus discharge
for S-1 and S-3 indicate the expected negative relationship though there is plenty of scatter(see Figures
2.7-18g and 2.7-18h).
TDS exceeds the secondary drinking water limits of 500 mg/I in all but one sample.The iron limit of.3
mg/I for drinking water is exceeded at both sites S-1 and S-3 in many of the samples. Irrigation standards
are also exceeded for iron (sites S-1 and S-3) in a number of samples.
Continued sampling during operation (see Section 4.8) has shown that water in tributaries draining the
mine site is unavailable for use as drinking water under primary and secondary standards. Irrigation
standards for continuously used water are typically exceeded for molybdenum, iron and occasionally
manganese and lithium.
Surface Water Quality, Eastern Expansion Area (PR-07)
Trapper submitted PR-07 in May of 2013 with the intent to extend the perimeter boundary of the mine
to the Knez Divide road,otherwise known as Moffat County Road 33. The following discussion details
baseline sampling of the pre-existing spring complex located in this area.
Sampling began for the Jeffway Gulch drainage as part of the PR-07 expansion to the permit boundary.
Jeffway Spring @ County Road 33 is a sampling location to monitor the spring complex located in the
southeastern edge of the permit boundary and flows into Jeffway Gulch in the same vicinity as the
unnamed tributary (Figure 2.7-15f).The site lies on the west side of County Road 33 just inside the
permit boundary.
Baseline water quality sampling began in April of 2014 and seven samples have been collected since that
time.Water quality results are shown on Table 2.7-18b.The water quality of the spring shows the
dominant cations as magnesium and calcium, and the dominant anions as sulfate and bicarbonate. The
samples can generally be characterized as magnesium-calcium-sulfate-bicarbonate type waters. Little
variance is seen in the water quality over the time period of sampling.
The water quality was compared to the primary and secondary drinking water standards and water
quality standards for the Williams Fork River and its tributaries.The spring exceeds the secondary
drinking water standards for aluminum, iron, manganese, sulfate and TDS.The water quality meets the
Regulation#37 Stream Classifications and Water Quality Standards for the Lower Yampa/Green River
published by the Colorado Water Quality Control Commission.
During the baseline sampling period no overland surface water flows were observed or sampled in the
Eastern Expansion Area. Further observations of surface water flows are included in permit section
2.7.4.1 and Table 2.7-12c. Spring monitoring will continue on the same interval as the other spring
monitoring sites within the permit boundary. Any precipitation related surface water flows are
anticipated to have similar water quality characteristics to existing drainages within the permit area.
2-451s Revision:
Approved: cew 2L��S