Appendix A Water Quality Memo - Laserfiche WebLink

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18 Traffic/Transportation Patterns The Santa Ana River is not used for transportation. Therefore, the proposed Project would not have an adverse effect on aquatic traffic/transportation patterns. Energy Consumption or Generation The Santa Ana River is not used for energy generation. Therefore, the proposed Project would not have an adverse effect on energy consumption or generation. Navigation The Santa Ana River within the Project area is not used for navigation. According to the NES(MI) prepared for the proposed Project, downstream of the Project area the channel has a direct nexus to the Pacific Ocean (a navigable water of the U.S.) and is tidally influenced at its mouth. However, the tidal influence does not extend to the Project area. Because the Santa Ana River is not used for navigation in the Project area, the proposed Project would not have an adverse effect to aquatic navigation. Safety As discussed previously, the proposed Project would improve the river hydraulics upstream of the bridge by lowering the water surface elevation and reducing the length of the subcritical flows by approximately 300 ft. Therefore, implementation of the proposed Project would have a beneficial effect on the flood control functions of the surface waters upstream of the Project area. Because the proposed Project would not increase flooding in the Project area, no safety impacts related to flooding would occur. 4.4 Short Term Impacts During Construction No Build Alternative Under the No Build Alternative, no improvements to Fairview Street between 9th Street and 16th Street would occur and the Fairview Street bridge over Santa Ana River would not be replaced. Therefore, no soil would be disturbed, and there would be no increase in the potential for soil erosion or sedimentation compared to existing conditions. Additionally, there would be no increased risk of spills from construction equipment or materials use. Build Alternative Pollutants of concern during construction include sediments, trash, petroleum products, concrete waste (dry and wet), sanitary waste, and chemicals. Each of these pollutants on its own or in combination with other pollutants can have a detrimental effect on water quality. During construction activities, excavated soil would be exposed and there would be an increased potential for soil erosion and sedimentation compared to existing conditions. According to the Draft Water Quality Management Plan (WQMP) (Civil Works Engineers 2019b) prepared for the proposed Project, the disturbed soil area during construction would be 1.15 acre. However, project construction may disturb additional area depending on any sound barriers incorporated into the proposed Project. In addition, there is a potential for chemicals, liquid products, petroleum products (such as paints, solvents, and fuels), and concrete- related waste to be spilled or leaked and transported via storm runoff into receiving waters. Construction activities within the Santa Ana River during bridge replacement have the greatest potential to impact water quality. However, construction within the river would not occur during the rainy season.