2016-12-09_HYDROLOGY - M1977493

• Permit No: M1977493
• IBM Index Class Name: HYDROLOGY
• Doc Date: 12/9/2016
• Doc Name: Request for Demonstration of Compliance
• From: Climax Molybdenum
• To: DRMS
• Email Name: ECS
• Media Type: D
• Archive: No

Demonstration of Compliance Climax Molybdenum Company
With Regulation 41 Permit M-1977-493
3.0 ARKANSAS RIVER WATERSHED
Appendix A presents the data calculations for Climax POC wells in accordance with Section 5.1
of the WQMP. Data in Appendix B were reviewed in accordance with Section 5.2.1 of the WQMP.
Manganese has been observed at concentrations above the CBSG table values at POC wells
ARwell and ARK-MW-001 D, and pH measurements below the lower end of the CBSG range of
6.5 have been observed at ARwell. Given the Climax operating and reclamation history (Section
T-1.2 of the Environmental Protection Plan — EPP), there is no information that indicates new or
increased sources of groundwater contamination were initiated in the Arkansas River Watershed
subsequent to January 31, 1994. Rather, most of the mine-related disturbance in the watershed
has been reclaimed and, as a result, water quality in the watershed has improved with time.
Therefore, ambient levels for manganese and pH can be determined following a review of
available information referenced herein which show levels deemed representative of groundwater
quality as of January 31, 1994.
The following sections provide supporting information for application of the CBSG Interim
Narrative Standard to determine or estimate existing ambient quality as of January 31, 1994.
3.1 Potential Contaminant Sources, EPFs and Reclamation
As described in Section T-5.1 of the EPP, the upper Arkansas River Watershed includes historic
underground mining support facilities, most of which have been reclaimed subsequent to January
31, 1994. No new or increased sources of groundwater contamination have been initiated in the
area subsequent to January 31, 1994.
Prior to closure of the underground mine, the entrance to the underground operation at Climax
was through 5-Shaft and the Storke Portal at the Storke Yard just east of the hairpin turn on
Highway 91. The following potential sources of contamination and Environmental Protection
Facilities (EPFs) remain in the upper East Fork Arkansas River Basin:
■ Impacted water from the flooded underground workings, controlled by the 5-Shaft
Pump Station, which began operation after underground mining ceased in 1994;
■ Run-off and seepage from the Storke Yard, collected and pumped to the water
treatment system in the Tenmile Creek drainage by the Storke Wastewater Pump
Station, which was constructed around 1980; and
■ Run-off from the Ceresco Ridge haul road above the Storke Yard.
Underground mining ceased in 1994, and since that time several reclamation projects were
completed in the area, including the following:
■ Reclamation of the former gravel pit, along the Arkansas River to the south-southwest
of the Storke Yard and Highway 91 (late 1980s into the early 1990s);
■ Equipment removal and building demolition in preparation for final reclamation
(beginning in 1995);
• Reclamation of the Storke Yard, including removal and/or regrading and covering of
mine waste rock material used for construction fill (post 1995); and
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