Laserfiche WebLink
Demonstration of Compliance Climax Molybdenum Company <br /> With Regulation 41 Permit M-1977-493 <br /> subsequent to January 31, 1994 shall be presumed to be representative of existing quality as of <br /> January 31, 1994. <br /> Similar to the Arkansas River Watershed, data prior to 1994 is available from POC well GW#2, <br /> as well as the internal upgradient well GW#1, which provides an opportunity to evaluate such data <br /> relative to more recent water quality data. As discussed above, the data at these locations <br /> indicate generally stable or improving water quality since January 1994. Therefore, the use of <br /> data from the available period of record for both the shallow and deep well at the POC location is <br /> appropriate to determine existing ambient quality as of January 31, 1994 and for establishing <br /> appropriate NPLs to assure that conditions are not allowed to deteriorate for parameters that are <br /> higher than BSGW Table Values in such data representative of January 31, 1994. The use of the <br /> entire data set from these wells considers the variability in observed conditions over time in <br /> determining representative ambient quality. <br /> The deep POC well TM-MW-002D, constructed in 2012, is located adjacent to GW#2, and the <br /> record of recently improving quality in the shallow aquifer at this location relative to water quality <br /> in January 1994, establishes the adequacy and appropriateness of using data from the available <br /> period of record for estimating ambient quality as of January 31, 1994. In the context of estimating <br /> ambient quality as of January 31, 1994, the data trends demonstrate that there is no indication of <br /> new or increased sources affecting water quality or otherwise affecting the representation of <br /> ambient quality as of January 31, 1994. <br /> 5.2.2 Ambient-Based Manganese and pH Values for TM-MW-002D <br /> TM-MW-002D is a deeper bedrock POC well, constructed in September 2012 adjacent to shallow <br /> alluvial POC well GW#2. Sampling at this location has been conducted on a quarterly basis since <br /> December 2012, with additional monitoring for manganese and pH on a more frequent basis in <br /> 2014. As described previously, based on data trends there have been no new or increased <br /> sources of groundwater contamination initiated in the Tenmile Creek Watershed subsequent to <br /> January 31, 1994. When considering that the manganese variability observed in groundwater <br /> from this well are believed to be naturally occurring and unrelated to anthropogenic sources,these <br /> data are deemed suitable to determine existing ambient quality as of January 31, 1994. Table 5- <br /> 1 lists all results for manganese and pH from this well through the third quarter of 2016 and the <br /> calculation of the ambient values. For pH,the mean value represents the log transformed average <br /> of the hydrogen ion concentration (10-P"). <br /> Table 5.1: Ambient-Based Manganese and pH Calculations for TM-MW-002D <br /> Manganese, <br /> Site Number Sample Date Dissolved Field pH, <br /> standard units <br /> (mg/L) <br /> TM-MW-002D 12/19/2012 0.037 8.7 <br /> TM-MW-002D 03/18/2013 0.103 6.3 <br /> TM-MW-002D 06/26/2013 0.104 8.5 <br /> TM-MW-002D 08/13/2013 0.029 8.3 <br /> TM-MW-002D 11/12/2013 0.048 6.8 <br /> TM-MW-002D 01/29/2014 0.0298 8.2 <br /> December2016 23 <br />