2005-099 - Overriding Considerations for the Alton Avenue Overcrossing at the SR-55 Freeway Project

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Draft Findings of Fact and Mitigation Monitoring Reporting Program (applies to CEQA only) the No Build Alternative and under the Preferred Alternative. For Site 3, the existing noise level is 62 dBA, and the predicted noise level for year 2025 is 67 dBA under the No Build Alternative and under the Preferred Alternative. Site I (Carriage Stop Motel) would not be substantially impacted. For Site 1, the existing noise level is 59 dBA, and the predicted noise levels for year 2025 are 62 dBA under the No Build Alternative and 62 dBA under the Preferred Alternative. Where future noise levels exceed the applicable NAC, noise abatement must be considered for reasonableness and feasibility, based on 23 CFR 772 and the Caltrans/FHW A Protocol. According to this Protocol, the noise abatement must achieve a minimum of five dB of noise reduction at the impacted receptor in order to be considered feasible. Other factors may also affect feasibility, including topography, access requirements (driveways, ramps, etc.), local cross streets, other noise sources, and safety considerations. Noise abatement, in the form of a property line noise barrier, was evaluated for Site 2, the Adagio Apartments and for Site 3, the single-family residence located at 110 Aiton Avenue. A noise barrier is not considered reasonable at Site 2 because it would block both vehicle and pedestrian access to this property from Main Street. A property line noise barrier at Site 3 would be feasible because it would provide at least a five-dB noise reduction. Noise abatement, in the form of a property line noise barrier, was evaluated for Site 2, the Adagio Apartments and for Site 3, the single-family residence located at 110 Aiton Avenue. A noise barrier is not considered reasonable at Site 2 because it would block both vehicle and pedestrian access to this property from Main Street. A property line noise barrier at Site 3 would be feasible because it would provide at least a five-dB noise reduction. The recommended noise abatement for Site 3 is a noise barrier wall that would be located at the property line, and will be 2.4 m (8 ft) high and 22.8 m (75 ft) long. Temporary Impacts (Construction) . During the construction phases of the Alton Avenue Overcrossing project, noise from construction activities may intermittently dominate the noise environment in the immediate area of construction. Demolition and grading, which require removal of existing structures, would result in the highest noise levels. Construction noise is regulated by Caltrans' Standard Specifications Section 7-1.011, "Sound Control Requirements." These requirements state that noise levels generated during construction shall comply with applicable local, state, and federal regulations and that all equipment shall be fitted with adequate mufflers according to the manufacturers' specifications. Because construction activity would be conducted in accordance with Caltrans' standard specifications (and by extension with local state and federal regulations), and because the noise would be short- term, intermittent, and dominated by local traffic noise, no adverse noise impacts from construction are anticipated. Mitigation: The City shall implement the following mitigation measures: NOl-I All equipment shall have sound-control devices no less effective than those provided on the original equipment. No cquipment shall have an unmuffled exhaust. NOl-2 As directed by Caltrans or the Cities of Santa Ana and Irvine, the contractor shall implement appropriate additional noise mitigation measures, including, but not ResojIllWA.wo..2tlQ~ng at SR-55 Page 32 of 49 K-20 April July 2005