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attempt to minimize the amount of additional background variability in the water . <br />quality data. With the installation of downgradient surface site HGSD3, HGTI <br />abandoned monitoring at HGSD2. <br />In addition, Colorado Wastewater Discharge Permit System (CDPS) monitoring is <br />conducted on a weekly basis ,as appropriate, at two pond outfalls (001 and 002) <br />associated with the spillways of the two sedimentation ponds located at the Loadout <br />(Truck Loop Pond and Rail Loop Pond). Locations of each surface water monitoring <br />site and NPDES outfalls are presented on Exhibits 12-1, Facilitea Map, 12-2, <br />Surface Water Control Plan Map, and Figure 13-1, Monitoring Site Location Map, in <br />Tabs 12 and 13. Discharge and water quality data collected at the five surface <br />water monitoring sites are presented in Tab 7, Hydrologic Description of this PAP. <br />Groundwater Monitoring. Groundwater monitoring was initiated at the Loadout <br />facility by HGCC in 1967 and utilized two shallow monitoring wells. The wells were <br />installed to monitor shallow groundwater in alluvial/colluvial deposits and shallow <br />bedrock (Lewis Shale). The wells (upgradient shallow well [HGDALI] and <br />downgradient shallow well[HGDAI,2]) were located proximate to the facilities area; <br />however, upon examination of the monitoring program as part HGTI's facility <br />permitting effort, HGTI determined the wells were not positioned above and below <br />all disturbance associated with the facilities area (see Exhibit 12-2). Figure 13- <br />2, Completion Report for Downgradient Shallow Well, presents a well completion <br />sketch for the downgradient shallow well (HGDAL2), which was completed in 1987 -(by <br />HGCC). HGTI is unable to locate a well completion report for upgradient shallow <br />well, HGDALI, however, it is HGTI's understanding that this monitor well was <br />completed in a similar manner and at a similar depth as depicted in Figure 13-2. <br />Monitoring for levels and water quality was conducted semiannually (spring and <br />fall) beginning in 1987, excepting 1988 and 1990, when an additional sampling round <br />was performed at both wells during the summer. Since monitor wells HGDALI and <br />HGDAL2 were partially completed in the Lewis Shall, HGTI and CDMG have concarna the <br />data from the wells may not be representative of Dry Creak alluvial chemistry. <br />As a consequence, a third well, HGDAL3, was installed approximately 800 feet <br />downgradient of the facilities area and associated disturbance on October 28, 1993. <br />Well completion and aquifer test information for HGDAL3 are presented in Tab 7, <br />Attachment 7-2. <br />TR-06 2 Revised OS/OS <br />