2014-06-09_HYDROLOGY - M1977342

• Permit No: M1977342
• IBM Index Class Name: Hydrology
• Doc Date: 6/9/2014
• Doc Name: Submittal of Annual Water Monitoring Report
• From: Climax
• To: DRMS
• Permit Index Doc Type: Hydrology Report
• Email Name: PSH
• Media Type: D
• Archive: No

CMC—Henderson Operations
DRMS 2013 Annual Water Monitoring Report
' June 2014
3.1.1 Point of Compliance Sampling Location: MNGW-1
' Deviations from NPLs of pH 6.5 - 8.5 were observed at the Mine POC well MNGW-1 during
monitoring events in December 2012 and May-August of 2013. These pH deviations ranged
from 5.9-6.4 standard units. A further summary of groundwater trends at MNGW-1 can be seen
' in the Groundwater Quality Assessment, Technical Memorandum (AJAX and Clear Creek
Associates, December 2013). No other trends, deviations or exceedances were observed in 2013.
Though within the NPL, the 2012 dissolved iron value of 603 ug/L has been identified as a
' statistical outlier based upon analysis via Rosner's method.
Tabular data for MNGW-1 is presented in Table 1, with accompanying Trend Evaluations 1-4,
' and provides a comparison to applicable NPLs.
3.1.2 Surface Water Sampling Location: BG-20
' BG-20 is located upgradient of the Henderson Mine in Butler Gulch and serves as an indicator of
background surface water quality. Data suggests no apparent anomalies were observed in 2013.
Tabular data for BG-20 is presented in Table 1 with accompanying Trend Evaluations 5-8.
3.1.3 Surface Water Sampling Location: CC-10
' CC-10 is also located upgradient of the Henderson Mine in the West Fork of Clear Creek and
serves as another indicator of background surface water quality. The limited data suggest a slight
increase in iron during the December 2012 and May 2013 monitoring event. Data suggests no
' apparent anomalies were observed in 2013.
The specific conductivity values for the December 2012 and November 2013 monitoring events
have been identified as a statistical outliers based upon analysis via Dixon's method.
' Tabular data for CC-10 is presented in Table 1 with accompanying Trend Evaluations 9-12.
' 3.1.4 Surface Water Sampling Location: CC-30
CC-30 is located downgradient of the Henderson Mine in the West Fork of Clear Creek. Data
suggests that no apparent anomalies were observed in 2013.
' The monitoring event on December 2012 produced four statistical outliers for manganese, iron,
specific conductivity, and sulfate. The latter three were determined outliers via Dixon's
methodology while manganese was identified using Rosner's method. Outlier methodologies are
determined based upon the number of data points available.
Tabular data for CC-30 is presented in Table 1 with accompanying Trend Evaluations 13-16
' 3.2 Henderson Mill
The Henderson Mill monitoring locations include POC well MLGW-7, as well as surface water
' locations WFR-20 and WFR-40. Graphical trends are presented as Trend Evaluations 17-28 of
this report. Baseline data for MLGW-ACR and newly proposed POC wells MLGW-15 and
MLGW-17 is presented in the 5-Quarters Water Quality Data and Baseline Monitoring Report
(Aquionix, 2014). It should be noted that for the purpose of trending the analytical data, results
reported as below the laboratory detection limit were included as a value of zero.
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