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
■ Restoration of a buried segment of the East Fork Arkansas River along the south side
of the Storke Yard (completed in 2008).
With the reclamation completed at present, issues related to run-off and seepage have been
significantly reduced and the following controls are designated EPFs to prevent potential impacts
to the Arkansas River Watershed:
■ 5-Shaft Pump Station (and associated Storke Pipeline);
■ Storke Wastewater Pump Station; and
■ Ceresco Ridge Haul Road Runoff Collection Ditch.
3.2 Data Evaluation
Groundwater data from monitoring well ARwell are available from September 1993. These data
indicate decreasing trends in concentrations of primary indicator parameters manganese, iron,
sulfate and TDS at this POC location over the period of record. Data for other indicator
parameters over this same period are dominated by results flagged as non-detect, and do not
indicate any type of trend.
Based on the general history of the area, and the review of data trends at ARwell, there is no
information indicating that new or increased sources of groundwater contamination have been
introduced in the upper Arkansas River Watershed subsequent to January 31, 1994. Therefore,
data obtained subsequent to January 31, 1994, are representative of existing quality as of January
31, 1994, in accordance with the CBSG Interim Narrative Standard (41.5(C)(6)(b)(iii)).
Consistent with the methodology approved by DRMS in Section 5.1 of the WQMP, the use of the
mean concentration plus two standard deviations of the baseline data set were used to compare
against monitoring data as the basis to demonstrate compliance with Regulation 41.
3.2.1 Analysis of Available Information to Determine or Estimate Ambient Quality
In accordance with the Interim Narrative Standard of the CBSG, data collected subsequent to
January 31, 1994 can be used to determine or estimate ambient quality as of January 31, 1994.
In all instances, DRMS is to exercise its best professional judgment as to what constitutes
adequate information to determine or estimate existing ambient quality, taking into account the
location, sampling date, and quality of all available data. In the situation where the available
information indicates that there have been no new or increased sources of groundwater
contamination initiated in the areas in question subsequent to that date, data generated
subsequent to January 31, 1994 shall be presumed to be representative of existing quality as of
January 31, 1994.
The long period of record at POC well ARwell provides an opportunity to evaluate data
representative of existing quality as of January 31, 1994 relative to more recent water quality data.
As discussed above,the data at this location indicates a clear decreasing trend from 1993 through
the third quarter of 2016. Therefore, the use of data from the available period of record for both
wells (ARwell and AR-MW-001 D) at this POC location is adequate to determine existing ambient
quality as of January 31, 1994 to assure that for such ambient values in excess of CBSG table
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