2016-06-02_HYDROLOGY - M1977342

• Permit No: M1977342
• IBM Index Class Name: Hydrology
• Doc Date: 6/2/2016
• Doc Name: Annual Watering Report - Groundwater Management Plan
• From: Climax Molybdenum
• To: DRMS
• Email Name: PSH
• Media Type: D
• Archive: No

CMC—Henderson Operations
DRMS 2015 Annual Water Monitoring Report
May 2016
MNGW-1 location. Once this evaluation is complete, a report will be submitted to DRMS with
recommendations to develop a successive plan
Tabular data for MNGW-1, along with applicable NPLs, is presented in Table 1. Accompanying
graphs are provided in Trend Evaluations 1-4.
2.1.2 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. No apparent trends or anomalies were observed in 2015.
Tabular data for BG-20 is presented in Table 1 with accompanying Trend Evaluations 5-8.
2.1.3 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. No apparent trends or anomalies
were observed in 2015.
Tabular data for CC-10 is presented in Table 1 with accompanying Trend Evaluations 9-12.
2.1.4 Surface Water Sampling Location: CC-30
CC-30 is located downgradient of the Henderson Mine in the West Fork of Clear Creek. No
apparent trends or anomalies were observed in 2015.
Tabular data for CC-30 is presented in Table 1 with accompanying Trend Evaluations 13-16.
2.2 Henderson Mill
The Henderson Mill monitoring locations include POC wells MLGW-7, MLGW-ACR,
preliminarily approved POC wells MLGW-15 and MLGW-17, as well as non-POC surface water
locations WFR-20 and WFR-40. Graphical trends are presented as Trend Evaluations 17-40 of
this report.
2.2.1 Point of Compliance Sampling Location: MLGW-7
MLGW-7 is a shallow alluvial well nested with MLGW-15 located downgradient of 1-Dam.
Monthly monitoring being conducted at MLGW-7 for an expanded parameter set as part of an
ongoing groundwater quality assessment concluded at the end of 2014. Field parameters
continued to be measured on a monthly basis until terminated in July, 2015 after DRMS granted
preliminary approval of revised NPLs for pH at Mill POCs. Sulfate continued a downward trend
in 2015 monitoring results at MLGW-7. No other apparent trends, deviations or exceedances
were observed in 2015.
Tabular data for MLGW-7 along with applicable NPLs is presented in Table 2. Accompanying
graphs are provided in Trend Evaluations 17-20.
2.2.2 Point of Compliance Sampling Location: MLGW-ACR
MLGW-ACR is the drinking water parameter POC well located in the Aspen Canyon Ranch
area. Baseline monitoring was performed over a period of five calendar quarters from the fourth
quarter of 2012 through the fourth quarter of 2013. NPLs were established for dissolved
selenium, dissolved zinc, pH and sulfate in the April, 2015 (DRMS, 2015). Results for iron and
5of8