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COLORADO OPERATIONS ® Climax Molybdenum Henderson Mill A Freeport-McMoRan Company 19302 County Road 3 Parshall, CO 80468 Phone(303)569-3221 June 8, 2021 RECEIVED UPS Tracking# 1Z 804 641 03 9362 4158 JUN '' 0 2011 Mr. Peter Hays DIVISION OFRE-CLAMATION Division of Reclamation, Mining and Safety MININGAND SAFETY 1313 Sherman St., Rm. 215 Denver, CO 80203 Re: Follow-up Notice for 3-Dam Seep Water Collection System Overflow, Permit No. M-1977-342 Dear Mr. Hays.- Pursuant to Rule 8.2.3 of the DRMS Rules and Regulations, Henderson Mill is providing this written follow- up notice to a phone call made to you on June 4, 2021. This notice is regarding water originating from the 3-Dam seepage collection system, which overflowed from an engineered overflow into a downgradient area where the water had once flowed and accumulated prior to construction of the collection system in 2010. The incident was discovered on June 3, 2021 at approximately 3:00pm. While driving by the area, personnel noticed surface water draining from the overflow pipe. Upon further investigation, the seep collection system was found to be overflowing from the upper vault into the above described area. The cause of this issue was due to a clogged pipeline between the upper dosing vault and the lower pump station. A sump pump and water truck were mobilized on June 4 to pump water out of the upper dosing vault, thereby stopping the overflow water. At this time, pumping water from the dosing vault continues until the pipeline can be cleaned and returned to normal operation and water is no longer overflowing from the vault. The following paragraphs correspond to the elements of the follow-up written notice set forth in Rule 8.2.3, paragraphs (a) through (e), of the DRMS Rules and Regulations: (a) After discovering the issue, Henderson employees immediately began investigation into the cause of the system overflow and began cleaning and pumping the water from the vault. (b) The overflowed water did not adversely impact human health, property or the environment. This is based on the known chemistry of the water and the location of the event. Water ran from the overflow to an area where the material had once flowed prior to system construction. At no time did any impacted water flow from the property or impact waters of the United States. (c) The contact person for this event is: Geoff Niggeler 19302 County Road 3 Parshall, CO 80468 Phone: 720-942-3631 (d) No monitoring or analyses were performed for this situation since the water from the 3- Dam seepage collection system was contained on-site and did not impact any natural water body.