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Summary of Impacts <br />Geology, Soils, and Seismic Conditions <br />The new courthouse would be constructed according to the Uniform Building Code seismic <br />zone 3 design specifications with consideration of the Oregon Structural Specialty Code (1997). <br />No unusual soils or foundation conditions are likely to occur on any of the alternative sites. <br />Nonetheless, a geotechnical study would be conducted as part of the design process. <br />Water Resources <br />Construction Impacts <br />During construction of the proposed facility, it may be necessary to dewater the foundation <br />construction areas to prevent ground water or stormwater from ponding at the bottom of the <br />excavation. Dewatering in excavation areas would increase the flow volumes discharged from <br />the site during construction and increase the transport of solids offsite, which could increase the <br />turbidity of runoff entering receiving waters such as the Willamette River. Without proper <br />controls, receiving water quality impacts could result from dewatering activities. <br />Operation of heavy equipment requires fueling and engine maintenance activities that involve <br />oil, grease, solvents, and other toxic engine fluids. These materials can be entrained in <br />stormwater runoff from leaks, accidents, and improper handling or disposal. Soils that become <br />contaminated can carry the adsorbed contaminants offsite into receiving waters. Damage to <br />aquatic life in the Willamette River could occur if an uncontrolled spill of fuel or other toxic <br />material occurs on the construction site and stormwater runoff or dewatering carries the material <br />offsite. Heavy equipment used for construction could increase the potential for spills of fuel or <br />other related products. Spilled material could also contaminate ground water beneath the <br />construction site. Lesser impacts could be caused by the cumulative effects of miscellaneous <br />leaks and drips of fuel, antifreeze, solvents, concrete curing compounds, asphalt emulsifier, <br />paints, and other materials used during construction. <br />Removal of any existing structures could result in short-term impacts from dust and debris <br />associated with demolition activities. Water quality impacts typically associated with demolition <br />activities include increased debris loadings to stormwater conveyance systems and increased <br />particulate loadings in runoff entering receiving waters. Proper controls are needed to prevent <br />water quality impacts resulting from demolition activities. <br />Operational Impacts <br />Currently, the alternative sites are fully developed and covered almost entirely by impervious <br />surfaces, including mostly rooftops and parking lots. The Alternative 1 site (the Riverfront site <br />New Federal Courthouse 7 Final E1S <br />