2003-01-15_REVISION - M1983176 - Laserfiche WebLink

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: ~;~'EP-21-2000 a ~_ ,.r. ~~9 THU OB ~ 45 Att BAtdKS AND GESSO LLC FAX N0. 303 274 8329 measures as part of the permitting process. OMG also asked that the Applicant submit a copy of the Clean Up Completion Report upon completion of remediation activities at the site. Response: The Applicant has submitted a Voluntary Clean Up Plan to, and received approval from, Colorado Department of Public Health and Environment, Hazardous Materials and Waste Management Division. A copy of the letter indicating CDPHE's approval is attached to this correspondence. Also included with the letter is a copy of amendments made to the plan by the Applicant, at the request of CDPHE. Lastly, the Applicant commits to submitting a Clean Up Completion Report subsequent to completion of the remediation activities on the site. Exhibit G -Water Concerns 9. DMG Comment (1): The Division states that "a drop of three feet cannot be considered a 'significant drop' unless the five quarters of groundwater monitoring (still to be submiried) supports this decision." A request was made for the Applicant to submit the data that has been gathered so far. Spec cation was also requested concerning which of the five wells on the site will be used for groundwater monitoring. Response (1): Attached, please find the groundwater monitoring results gathered by the Applicant to date. Based on Current baseline monitoring, the average quarterly fluctuation in depth to groundwater of all monitoring wells has been 0.32 feet (3-7/B inches). Using these statistics, the Applicant assumes that a three foot drop in water levels is a reasonable threshold. 7o clarify, there are five wells located on the site and all of the wells will be monitored. DMG Comment (2): The Division also raised questions over the mitigation measures proposed by the Applicant pertaining to drops in well water levels. The Applicant was asked to identfy specific measures which would be taken, in order of precedence, and to identify points at which new measures would be attempted. Response (2): Specific mitigation measures, in order of precedence, are (A) a recharge ditch or other infiltration structure filled with water; (l3) water trucked into site or to location of wells affected by mining activity; and (C) drill affected wells deeper. Each successive measure will be attempted in the event the previous measure fails to restore water levels to within three feet of the baseline. DMG Comment (3): Lastly, the DMG commented that the Applicant's request to be permitted to expose groundwater after four quarters of groundwater monitoring is in conflict with the Division's policy that five quarters of monitoring take place. The Applicant was asked to commit to five quarters of groundwater monitoring before groundwater is exposed at the site. Response (3): The Applicant commits to exposing no groundwater until five quarters of groundwater monitoring data are compiled and submitted to DMG. Five quarters Of data will available in approximately January of 2001. P. 03