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Mr. Michael Cunningham 2 <br />CDRMS <br />July 16, 2013 <br />into the colluvium through the floor of the TSF. The geonet is an HDPE drainage <br />material intended to transmit fluids. This material will protect the GCL during the <br />installation process and will allow the continuation of inflow infiltration into the colluvial <br />soils. <br />2. The Applicant has provided a detail drawing for the sub - surface drain. Specify' the <br />average flow of groundwater which has been observed in the seep. In addition, please <br />explain how the dimensions of the sub - surface drain were selected. <br />Response: Please see response to Question 1. UMC proposes the installation of a geo <br />liner below the GCL in groundwater seepage areas. <br />3. The Applicant has stated the leak detection system will be tested after it has been <br />installed. Please describe the testing process. <br />Response: The leak detection system is not tested during installation. It is a secondary <br />system, to the polypropylene primary system which is installed simultaneously with the <br />GCL. The contractor installing the GCL, leak detection and polypropylene liners will <br />certify that the installation was performed according to the engineer's specification. <br />Testing will only be done on the polypropylene liner as required for certification. <br />4. The Applicant has stated the Division will be notified if a leak is detected in the <br />composite liner. Please commit to notifying the Division in writing within 48 hours of <br />detecting a leak. <br />Response: UMC commits to notifying the Division in writing within 48 hours of detecting <br />a leak. <br />5. The proposed leak detection system appears to cover less surface area of the CGL than <br />the currently approved leak detection system. Will the proposed leak detection system <br />be installed in strips, or will the entire surface of the GCL be covered by the leak <br />detection system? <br />Response: The original design called for the leak detection system to be installed in <br />strips. This design has since been modified. The current plan calls for the entire surface <br />of the GCL to be covered by the leak detection system. <br />6. According to the manufacturer's recommendations the liner material contractor must <br />have prior experience installing GCL's. Please confirm that the liner material contractor <br />has prior experience installing GCL's and briefly describe his experience. <br />Response: UMC has not yet selected a liner installation contractor. However, last <br />summer we sent RFQ's to qualified contractors and have narrowed our selection to two <br />potential installers. Both contractors are Colorado -based companies with experience in <br />liner installation, are supplied directly by CETCO, our GCL manufacturer, and are <br />approved by the manufacturer to install their product. <br />