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DRMS CEMEX M1977-208 Quarterly Report <br />April 6, 2009 <br />Page 4 <br />Under TR-8 & 9, compliance wells were drilled into the Fort Hayes and St.Vrain alluvial aquifer <br />(CEM-005, CEM-004). Water was not present in CEM-005, which replaced CEM-001 as the <br />compliance well. The purpose of these wells in each TR is to detect the presence of a "plume" of <br />water migrating from C-Pit. While variations in water quality parameters are observable in both <br />CEM-001 and CEM-004, neither shows indication of a plume. Any detectable increase in <br />selenium is likely background selenium in the surrounding media and irrigation waters, <br />particularly in CEM-004 which is surrounded by grazing and heavy irrigation. The compliance <br />well, CEM-005, still shows no migration of water. The purpose of monitoring for seeps and <br />springs and measuring the water level in C-Pit was to ensure that there is no migration to the <br />alluvial formation. CEM-001 shows a delayed response in water level, but there is apparent <br />attenuation of water quality parameters between CPit and the well. <br />The purpose of the piezometers and CEM-003 was to help identify potential sources of water. To <br />date, it appears that the Boulder Feeder Canal was a large source of the inflow, which has been at <br />least partially mitigated. <br />Referring back to CEM-001, the past year's analytical trend does not seem to indicate any <br />migration of C-Pit water. Variation in water quality appears to be more tied to irrigation season <br />and the influence of localized groundwater tables. One of the constituents of interest, selenium, <br />is known to have elevated background levels in this regional area's irrigation supply and growing <br />media. These elevated background levels for selenium appear more consistent with the results <br />obtained here. <br />At this point, CEMEX recommends that the Division and CEMEX review the goals of this <br />monitoring program in order to establish the most prudent course of actions, determine if any <br />monitoring and/or remediation modification is required, and identify what course of action <br />should be taken related to closure of CEM-005 and reestablishment of compliance well. <br />If there are any questions on the above information or the attachments, please contact me at <br />(303) 823-2115. <br />Sincerely, <br /> <br />Monica Sowders <br />Environmental Manager <br />5134 Ute Hwy PO Box 529 <br />Lyon, CO 80540 <br />Encl.\ Analytical Laboratory Reports, Environmental Sciences Corporation <br />Cc: (via email) <br />Alan Notary, Brown & Caldwell