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III. Environmental Setting, Impacts,and Mitigations <br /> K. Hydrology, Geohydrology,and Water Quality <br /> For the proposed project,these guidelines are also interpreted such that potential violations of <br /> State and Federal regulations regarding hydrology,geohydrology, and water quality are <br /> considered significant impacts. This interpretation dictates that any potential degradation of the <br /> ground water quality from present conditions,regardless of existing contamination,would be a <br /> significant impact. <br /> Impact K.I. Reconfiguration and relocation of Little Johns Creek could alter the flow <br /> regime and affect flow velocity,erosion and sedimentation on the site or in the adjacent <br /> downstream reach of the stream. (ADVERSE) <br /> The existing channel of Little Johns Creek would be reconfigured and relocated in the initial <br /> construction period. The creek would be realigned to the north and west of the existing landfill <br /> (Figure II.3). This realignment would increase the overall channel length by three percent(with <br /> an associated small decrease in bed slope). The new creek channel would have a geomembrane <br /> liner,covered with dirt and rip rap. <br /> Changes in the channel length,eliminating sinousity, and lining the channel would change <br /> channel parameters: bed slope and configuration,bed roughness (friction)and the amount of <br /> seepage loss. <br /> The existing curvilinear stream channel crossing the site would straightened, and the <br /> straightening, along with the decrease in bed slope,would change the number and location of <br /> areas with relatively higher and lower velocity. These factors would influence the location of <br /> potential erosive action and deposition on the site and at the downstream margin of the project. <br /> The project would be required to comply with the County storm drainage master plan design <br /> guidelines for the final configuration of the outfall. <br /> The decreased sinousity and replacement of natural bed materials would decrease roughness and <br /> friction loss,which could increase velocities,but the decrease in slope would tend to lower <br /> velocities. Decrease seepage loss through the bed would maintain higher total flow volume in <br /> the channel and could contribute to higher velocities. <br /> The net effect of these changes has not been quantified,but would not be expected to cause <br /> significant impacts to erosion and deposition on the site or in receiving waters. <br /> III.K.11 <br />