2020-06-08_HYDROLOGY - M1977493

• Permit No: M1977493
• IBM Index Class Name: HYDROLOGY
• Doc Date: 6/8/2020
• Doc Name: Water Controls
• From: Climax Molybdenum
• To: DRMS
• Email Name: DMC
• Media Type: D
• Archive: No

m Climax Molybdenum Climax Mine
�R ® Highway 91 - Fremont Pass
Climax,CO 829
A Freeport-McMoRan Company Phone[phone]
Fax[phone]
Sent by Email
June 4, 2018 RECEIVED
Mr. Dustin Czapla,Environmental Protection Specialist JUN 0 8 2020
Colorado Division of Reclamation, Mining and Safety
1313 Sherman St.,Rm. 215 DIVISION OF REcWIATION
Denver,CO 20203 MINING AND SAFETY
Re: McNulty Water Controls—Climax Mine Permit No.M-1977-493
Dear Mr. Czapla:
On Tuesday,June 2, 2020,Climax completed the first inspection for the year of the Phase I McNulty
Water Controls that were installed in the summer of 2019. During the inspection, it was discovered that
the overburden stockpile facility (OSF) underdrain system had failed to convey water as intended
resulting in a failure of an Environmental Protection Facility (EPF) as defined in Rule 8.The underdrain
system was designed to collect the contact water from the McNulty OSF and convey it in a pipe to the
McNulty Ditch which takes it to the Sludge Densification Plant (SDP) for first stage water treatment.
There is a secondary system that collects other incidental contact water from the area,coveys it to the
bottom of McNulty Gulch and finally through a culvert under Highway 91 and into Tenmile Tailings
Pond.
During the inspection, it was determined that the contact water from the McNulty OSF was bypassing the
underdrain system and was instead reporting to the bottom of McNulty Gulch and into the Tenmile
Tailings Pond.This incident did not result in adverse impacts to human health,property or the
environment.The immediate actions taken to correct the situation was to dig a small trench to redirect
flow back into McNulty Ditch.After evaluation with the design engineer, it was determined that inlet to
the underdrain was not adequate for surface flows and instead was designed for when the OSF was in
place and flows would be subsurface in nature.
This area is expected to experience surface flow for the next year or two due to Climax's reduced
production and stripping so an interim solution has been identified.When runoff is complete and flows
decrease,the inlet pipe for the underdrain will be excavated and graded riprap will be placed around the
inlet pipe to allow the surface flows to enter the pipe directly. A trash rack will also be utilized to ensure
the inlet stays free of debris and rocks.In the interim,the area will be inspected daily to ensure the water
continues to report to McNulty Ditch and the East Inspector remains unimpacted.
Please feel free to contact me at [phone] or at [e-mail] if you need any further
information regarding this matter.Thank you for your continued assistance with Climax Mine.
Sincerely,
A d&7
Diana Kelts
Environmental Manager