20A - AA FIRST ST BRIDGE REPLACEMENT PROJECT

Home Browse Search

LSA ASSOCIATES, INC. JULY 2010 INITIAL STUDY/MITIGATED NEGATIVE DECLARATION FIRST STREET BRIDGE REPLACEMENT PROJECT CITY OF SANTA ANA C. Result in a change in air traffic patterns, including either an increase in traffic levels or a change in location that results in substantial safety risks? No impact. The proposed project is a bridge replacement and street widening project and will not alter air traffic patterns. The site is located approximately 8 miles from John Wayne Airport. No impacts are anticipated and no mitigation is required. D. Substantially increase hazards to a design feature (e.g., sharp curves or dangerous intersections) or incompatible uses (e.g., farm equipment)? Less than significant impact. The proposed project will replace a bridge over Santa Ana River and widen First Street 300 feet east and west from the bridge. The proposed project will require only minor changes to the roadway profile. The existing bridge deck width is about 80 feet, whereas under the proposed project conditions the bridge will increase by about 30.5 feet to the north and 7.5 feet to the south. The total width at First Street will increase from 53 feet to 80 feet. A new proposed vertical crest curve over the bridge will meet the 45 mph design speed requirements and will be in close relationship to the existing profile. In addition, a new approximately 410 foot long, 4 to 12-foot high retaining wall will be built in northeast quadrant to address the grade difference resulted from the First Street widening. The proposed project will not change the design of any local intersections. The new bridge will conform to current building standards and would not increase hazards to a design feature. Therefore, less than significant impacts are expected and no mitigation is required. E. Result in inadequate emergency access? Less than significant impact. The proposed project will not result in inadequate emergency access because it will improve operation of First Street. The proposed project is a bridge replacement and a street widening to match up the existing configuration at the east and west ends of the project limits. An approximate 30 foot widening will occur on the north side of the First Street, whereas the widening on the south side of the First Street would be minimal. The widening will not substantially impact the Santa Ana River Access/ Maintenance Road which is located on the project site because safe passage and minimum clearances will be maintained. The access from both sides of First Street to the maintenance road will require construction of new driveway approaches, and will result in minor realignment and asphalt paving to join the existing maintenance road. The widening on the north side may also require the westerly end of the retaining wall in the northeast quadrant to extend northerly along the Manufactoring Housing Park to support the access road and address grade differential in that areas. During the project construction, First Street will remain operational and one travel lane in each direction will be maintained. Therefore, less than significant impacts are expected and no mitigation is required. F. Result in inadequate parking capacity? No impact. The proposed project does not involve expansion of any dwelling units, and therefore, will not result in inadequate parking capacity. The proposed project will replace a bridge over Santa 07/25/10 «P:\DMJ0701\MND\4.0 Environmental Analysis.doc» 4-41 20A-92