20A - AA FIRST ST BRIDGE REPLACEMENT PROJECT

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LSA ASSOCIATES, INC. INITIAL STUDYIMITIGATED NEGATIVE DECLARATION JULY 2010 FIRST STREET BRIDGE REPLACEMENT PROJECT CITY OF SANTA ANA No impact. The proposed project is a bridge replacement and street widening in an urban and built- out environment. Because the project would not affect any existing structures (the project occurs in existing right-of-way) no historic properties will be affected according to the Historic Property Survey Report (LSA, July 2010). First Street Santa Ana Bridge was initially built in 1937, widened in 1959 and seismically retrofitted in 2005. The existing bridge is listed as Category 5 in the Caltrans Historic Highway Bridge Inventory: Bridge Number 5500022 and is not eligible for listing on the National Register. The construction activities will be also conducted along First Street with no off-site construction activities or staging. The shoulders of the First Street are highly unlikely to contain significant historical resources within the project limits. The shoulders of the road were previously disturbed, and the soil was graded and compacted. Therefore, minor excavation, grading, and other construction activities that will occur within the street shoulders are not expected to result in the discovery of previously unknown historical resources. Therefore, no impacts to historic resources as defined in Section 15064.5 are anticipated. B. Cause a substantial adverse change in the significance of a unique archaeological resource pursuant to define Section 15064.5? No impact. The proposed project is located in a completely built-out area and construction will occur on previously disturbed lands. The site was previously graded, and covered with concrete or asphalt. In addition, the depth of excavation for the bridge foundations (4 feet maximum) is not expected to exceed the previously prepared soils under the bridge foundation. The widening of First Street will also occur in previously disturbed soils, where no archaeological resources are expected to be found. The proposed project is not anticipated to impact archaeological resources, and no mitigation is required. C. Directly or indirectly disturb or destroy a unique paleontological resource or site? Less than significant impact. The area of the project site is already built out and completely covered with impervious surface (paved). The soils were previously disturbed and compressed, so the sensitivity of the area for paleontological resources is low. The project site may contain unknown subsurface fossil remains below grade or in the alluvium of Santa Ana River. Implementation of the project will require excavation of up to 4 feet and some trenching for the bridge piles, and foundations under the surface in the Santa Ana River Channel. Excavation deeper than 10 feet bgs may result in encounter of Pleistocene sediments (greater then 10,000-year-old) which are rich in paleontological resources. Since no excavation deeper than 10 ft bgs will occur during the project construction there is very low potential to encounter Pleistocene aged sediments. The First Street widening will occur on both sides of the street and will result in addition of one through lane in each direction. The shoulders of the First Street within the right-of-way were previously disturbed, compacted, and graded and the likelihood of finding known or unknown paleontological resources is low. The construction activities will not likely affect paleontological resources since none of them exist on the site. Therefore, impacts to paleontological resources are not anticipated to occur as a result of the project, and no mitigation is required. D. Disturb any human remains, including those interred outside of formal cemeteries? 07/25/10 «PA\DMJ070l\MND\4.0 Environmental Analysis.doc» 4-14 20A-65