Laserfiche WebLink
In addition, in conversations with DBMS, WQCD has been made aware that tailings continue to <br />be deposited on site as a result of ongoing milling operations which resumed at the restart of the <br />Climax mine. These ongoing tailings depositions include both historic tailings areas (Tenmile <br />TSF) and newly improved/expanded areas (Mayflower TSF). It is our opinion that this activity <br />would meet the definition of a "new or increased sources of groundwater contamination", and <br />therefore not allow the presumption that data collected after January 31, 1994 would be <br />representative of existing ambient conditions prior to that date. <br />Regulation 41 contains manganese standards of 0.05 mg/L for domestic water supply use and <br />0.2 mg/L for agricultural use. The agricultural use standard only applies where there are acidic <br />soils. However, currently there is neither a domestic use or agricultural use of the groundwater <br />on the climax mine site so another use classification would be appropriate. Further study would <br />be required to set an appropriate concentration of manganese in the groundwater to insure this <br />classified use is protected. <br />Groundwater Quality Data <br />At the request of DRMS, WQCD examined the historic data provided by Climax. Since Climax's <br />permit encompasses three different drainage basins: Tenmile Creek, Eagle River, and Arkansas <br />River Basins, and because the data in each of these three basins vary in pattern, sample size, <br />and concentration. WQCD examined the data as three separate sets. <br />All of the plots in this memo use box and whisker plots. These plots allow us to visualize the <br />shape, distribution, variability, and central value of a data population. The box is drawn from the <br />25% to the 75%. The Bold line in the middle of the box represents the median value. The <br />whiskers are drawn to extend from the quartiles to the extreme values, and outliers are <br />represented as dots beyond the whiskers. <br />In this analysis all of the available data was broken up into 5-6 year populations. The date <br />ranges for the the populations are as follows: Data Pre -1994(A), 1995-1999(B), 2000-2005(C), <br />2006-2011(D), 2012-2017(E). Although for population E our data ended at various times in <br />2016. <br />Tenmile Creek Basin <br />In the Tenmile Drainage two wells have historic as well as modern data. These two wells are <br />GW#1 and GW#2. Both wells have the same median concentration for pre -1994 dissolved <br />manganese data of 0.02 mg/L with a sample size of 30. This historic concentration is well below <br />the domestic water supply standard of 0.05 mg/L. The current dissolved manganese data <br />shows a median concentration of .005 mg/L. <br />