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SEP-05-2003 FRI 09127 AM BANK5 AND GESSO LLC FAX N0. 303 274 8329 <br />• Page 3 September 4, 2D03 <br />were drilled in early spring of 2003, prior to initiation of irrigation, this data represents a point in time <br />measurement of the natural conditions in this area. <br />The groundwater level certainly changes throughout the year as well as from year to year, depending <br />on the prevailing Gimadc and ircigatlon conditions. Because of this, a pit that is dry in December may <br />become wet in July. The proposed-plan indigtes that K water is encountered excavation will stop and a <br />twofoot layer of fill material will be placed over the area. This development plan virtually assures a dry <br />pit. <br />If at some point the applicant decides that it is feasible to mine below the groundwater level, a <br />monitodng system should be developed to gain an understanding of the water levels and gradients in <br />the area. At that time I would recommend that a set of groundwater observation piezometere be <br />Installed and data routinely collected to monftor the location and fluctuation of the water surface. <br />As discussed above, even if the pit is operated as a wet pit, with the appropriate augmentation plan, it <br />will have very IiWe effect on down-gradient springs, ponds or drainages. The extent tc which a pond <br />could alter the groundwater hydraulics responsible for transport of water through the aquifer would be <br />proportional to the amount of drawdown created by wntinuously pumping the ponds to a level lower <br />than the prevailing surrounding level. It Is hard to imagine pumping down a gravel pit pond by more <br />than a couple of feet resulting in a very small cone of depression in the worst-case scenario. In this <br />case, the continued supply of groundwater flow to the nearby springs is more directly related to the <br />inflow and storage components of the hydrologic balance. <br />4. Storm water runoff <br />The State Engineers policy requires that impounded storm water runoff be released to the stream <br />system within 72 hours of impoundment. Because of the historic agricultural nature of this site there are <br />no natural drainages. Storm water from the fields is collected 6y a system of wastewater ditches and <br />moves offstte in this manner, For the proposed project, storm water directed toward the excavation <br />area and impounded will need to be pumped or gravity piped to a stream or wastewater ditch in order <br />to meet this requirement. <br />5. Water quality <br />Two possible water quality issues should be addressed. The first is sediment contamination from storm <br />water runoff released to a downstream ditch or steam channel. The nature of the proposed gravel <br />mine mandates that all surface How toward the pit is confined wtthin the pit. The impoundment of storm <br />water runoff in a detention pond is designed to allow time for settling of sediments prior to release. <br />Tha second issue is contamination of surface and/or groundwater from chemicals such as petroleum <br />products used in the operation. All pertinent Slate of Colorado health and environmental regulations <br />regarding the transport, use and storage of chemical and petroleum products should be smcny adhered <br />to. <br />6. Hydrologic Impacts <br />The previous discussion Identifies issues and' hydrologic impacts of the proposed project. Those that <br />have received the most attention by project opponents and those that I feel are significant are <br />summarized here. <br />• The act of digging a pit and operating a dry mine will not impact downstream water rights or <br />flows to other springs, ponds or drainages. <br />If at some point in the future the applicant modifies the application to allow ponds, I do not <br />foresee any significant impact on the flowrate or volume to downstream water rights, etc., if <br />done according to plans and state regulations including; <br />o no pumping of pit water outside of the project area <br />o no rerouting o1 flow from one end of projad to the other <br />o appropriate augmentation to account for evaporation and seepage losses <br />• The elimination of applied inttiation water may have a significant ett'ect It should 6e noted <br />however, that this could occur with or without the proposed project, <br />N. U4 <br />