2017-046 - Approving Addendum Nos. 1 and 2

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Santa Ana/Garden Grove Fixed Guideway Project Addendum • Human annoyance to residential land use — 145 Feet • Human annoyance to institutional land use — 115 Feet Any structures within the distances identified above would be considered impacted due to use of construction equipment such as a vibratory roller. The proposed modified alignment would reduce the minimum distance to a residential structure to 37 feet. While this distance is within the annoyance area it is outside of the potential damage area. Traction Power Substation Noise Analysis The noise sources on TPSS units are the transformer hum and noise from cooling systems. The wall mounted HVAC units are the primary noise source on the proposed TPSS units. TPSS units 1 and 4 are located in residential areas. Table N of the Supplemental Noise and Vibration Technical Analysis (see Appendix D) shows the predicted noise level at the TPSS sites. This table also lists the FTA noise impact criteria, in which a noise level above the specified dBA would be considered an impact. For TPSS unit 1, a noise level exceeding 54 dBA would be considered an impact. For TPSS unit 4, a noise level exceeding 59 dBA would be considered an impact. As shown in Table N, noise levels would be 42 dBA at TPSS unit 1 and 46 dBA at TPSS unit 4. These noise levels are less than the specified thresholds of 54 dBA (unit 1) and 59 dBA (unit 4), therefore, there would be no impact associated with the TPSS units. However, it is recommended that the following measures be implemented to ensure that the impact is below a level of significance: • Orient the TPSS unit so that the HVAC units, the primary source of noise, are pointing away from the nearest residence. At the residential locations, the TPSS units will be designed so as not to exceed a maximum noise level of 45 dBA at a distance of 50 feet from the unit or at the setback line of the nearest building, whichever is closer. The potential noise and vibration impacts associated with the construction and operation of the Project were evaluated in the EIR. Since the certification of the EIR, there have been some design modifications that have the potential to change the noise and vibration characteristics of the proposed Project as evaluated in the EIR. These design modifications have been evaluated as summarized above. Based on this supplemental evaluation, it has been determined that the proposed design modifications would not result in a new impact, increase in the seventy of an impact, or require the implementation of a new mitigation measure as evaluated in the EIR. No additional noise or vibration impact would occur and the conclusions and mitigation measures identified in the EIR remain accurate and applicable to the proposed Project. Air Quality The potential air quality and greenhouse gas emissions (global climate change) impacts associated with both the construction and operation of the proposed Project were evaluated in the EIR. There have been no changes to the air quality environment as evaluated in the EIR. The proposed miner design modifications would change some of proposed improvements within the corridor, however, the general Project constructions characteristics as described in EIR would not be altered in such a manner as to result in an increase in the daily construction emissions, and no new mitigation measures would be required. In terms of short-term, construction -related air quality impacts, as described in the EIR (and applicable to the Project with the proposed design modifications), construction activities would be completed in a segment by segment basis to minimize the disruption to local residents and businesses in the Study Area. As concluded in the EIR, there would be no exceedances of South Coast Air Quality Management District (SCAQMD) regional significance thresholds as a result of daily construction emissions. This conclusion would still apply with implementation of the proposed Project modifications as the construction parameters and characteristics would be the same, no new significant short-term air 131P age 1170726.1