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Mr. Michael Cunningham 3 <br />CDRMS <br />August 16, 2013 <br />Response: <br />Same response as "1 a" above. The perched aquifer was encountered during embankment <br />construction approximately 11 months ago. Over this time, it was observed that ponding <br />generated from inflows (which were initially flowing at a higher rate) remained the same size <br />indicating equilibrium to infiltration into the colluvium. Further, the amount of ponding has <br />deceased proportionally to the decrease of inflows experienced since September 2012. <br />High inflows prior to GDL installation will necessitate alternative methods (e.g. subdrain system) <br />of GCL installation. UMC will work with the Division to obtain permission to install an alternative <br />system, if required. <br />c) Provide a brief analysis in regard to how the extent of the seeps may be impacted by <br />increased inflow and describe how the installation of the geonet will be altered to accommodate <br />seeps with an increased surface area. <br />Response: <br />As stated above, UMC agrees with the Division that inflows from seeps will increase over time <br />with increased precipitation. <br />Inflows from the perched aquifer were much greater during the construction of the embankment <br />in late summer 2012. At that time, it was determined that a subdrain system would be required <br />to be in place prior to the installation of the GCL and was initially proposed by UMC. However, <br />this spring (after the snow melt) we had observed that inflows were materially lower, and a less <br />costly mitigative measure — GDL — was possible. <br />Should UMC experience high inflows prior to installation, a Technical Revision for a subdrain <br />system will be submitted to the Division. <br />d) Provide a drawing showing the approximate location of the seeps and the approximate <br />location of the geonet installation. <br />Response: <br />See attached drawing. The red shows areas affected by the seeps. The blue highlighted area <br />shows the proposed GDL. The GDL will be placed 5ft above the seep on the embankment and <br />5ft past the ponding in the embankment floor. Ponding occurs at the base of the embankment <br />and extends about 5ft onto the embankment floor; therefore the GDL will extend approximately <br />10ft from the base of the embankment. Note that the area affected by seeps is clearly defined. <br />e) Provide a detailed description of how the geonet will be installed, including any specifications <br />for anchoring. <br />Response: <br />The GDL will be of and installed by industry- standard specifications as summarized. <br />Specification: <br />The GDL shall be 220GN manufactured by US Fabrics, Inc. or equivalent. Any alternative GDL <br />material submitted for Engineer approval must demonstrate performance equivalency to the <br />property requirements and testing methods as shown in Tables 1 and 2. <br />