2017-05-31_HYDROLOGY - M1977342

• Permit No: M1977342
• IBM Index Class Name: Hydrology
• Doc Date: 5/31/2017
• Doc Name: Water Monitoring - Groundwater
• From: Climax Molybdenum
• To: DRMS
• Email Name: PSH
• Media Type: D
• Archive: No

CMC—Henderson Operations
DRMS 2016 Annual Water Monitoring Report
May 2017
MLGW-ACR to cease. In the past, Aspen Canyon Ranch has been operated year round resulting
in regular use of the well. The samples taken during the vacancy were noted as red in color and
resulted in significantly higher than usual dissolved iron and dissolved manganese
concentrations, which are not representative of typical conditions. Specifically, samples taken on
November 23, 2015 and February 3, 2016, during the vacated time period, produced results
containing outlier data for dissolved iron, at a value of 2920 ug/L and 3310 ug/L, and dissolved
manganese, at a value of 1100 ug/L and 770 ug/L, respectively. These outliers were established
using the Rosner's statistical method. There are currently no established NPLs for iron and
manganese at MLGW-ACR. Henderson intends to rehabilitate or replace the well using standard
practices upon the approval of the property owner. No other apparent trends, deviations or
exceedances were observed in 2016.
Tabular data for MLGW-ACR along with applicable NPLs is presented in Table 2.
Accompanying graphs are provided in Trend Evaluations 21-24.
2.2.3 Point of Compliance Sampling Location: MLGW-15
MLGW-15 is a deeper well nested with MLGW-7 located just downgradient of 1-Dam. No
apparent trends, deviations or exceedances were observed in 2016.
Tabular data for MLGW-15 along with applicable NPLs is presented in Table 2. Accompanying
graphs are provided in Trend Evaluations 25-28.
2.2.4 Point of Compliance Sampling Location: MLGW-17
MLGW-17 is a shallow alluvial well located downgradient of 3-Dam. No apparent trends,
deviations or exceedances were observed in 2016.
Tabular data for MLGW-17 along with applicable NPLs is presented in Table 2. Accompanying
graphs are provided in Trend Evaluations 29-32.
2.2.5 Surface Water Sampling Location: WFR-20
WFR-20 is located upgradient of the Henderson Mill in the Williams Fork River and serves as an
indicator of background surface water quality. No apparent trends or anomalies were observed
in 2016.
Tabular data for WFR-20 is presented in Table 2 with accompanying Trend Evaluations 33-36.
2.2.6 Surface Water Sampling Location: WFR-40
WFR-40 is located downgradient of the Henderson Mill in the Williams Fork River. No
apparent trends or anomalies were observed in 2016.
Tabular data for WFR-40 is presented in Table 2 with accompanying Trend Evaluations 37-40.
3.0 Conclusion
This report summarizing annual water monitoring data collected for each POC well and non-
POC long-term surface water monitoring location meets the conditions of the Henderson GWMP
reporting requirements. In accordance with the GWMP, Henderson has provided a summary of
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