2017-046 - Approving Addendum Nos. 1 and 2

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Santa Ana/Garden Grove Fixed Guideway Project Addendum As disclosed in the EIR, all severely impacted receivers would be reduced to moderate or no impact after the implementation of proposed mitigation. Eliminating the horn sounding at receptors R10 and R13 would reduce the noise impact from severe to moderate. Therefore, no barriers are recommended at those locations. Streetcar Vibration Analysis The proposed Project modifications would affect the vibration level results as presented in the February 2012 Noise and Vibration Technical Report provided as an appendix to the EIR. Beginning at Harbor Boulevard and ending at Raiff Street the proposed modifications would implement the following changes to the previously approved Project. • The proposed modification would increase the average train speed within the PE ROW from 35 to 45 mph • The proposed modification would shift the railroad alignment within the PE ROW to the north. Impact of Proposed Design Modifications Table L of the Supplemental Noise and Vibration Analysis lists the vibration levels calculated for the proposed alignment. This table reflects the change in vibration levels associated with the increase in speed and the change in centerline location. There are only Land Use Category 2 and Land Use Category 3 noise receptors located within the vicinity of the project modifications. Land Use Category 2 includes residences and buildings where people normally sleep. Land Use Category 3 includes institutional land uses with primarily daytime and evening use. The impact threshold for Land Use Category 2 is 72 VdB and for Land Use Category 3 is 75 VdB. As shown, the vibration levels are below the impact threshold at all receptor locations. Therefore, no minimization design features are required. Construction Vibration Analysis Construction of the proposed Project may require pile driving and has the potential to result in temporary vibration impacts to structures and humans. The potential use of pile driving is associated with the Project as evaluated in the EIR. However, the design modifications specifically do not trigger the need for the use of pile driving. The 2012 Noise and Vibration Technical Report (URS) determined that residences located within 100 feet of the Westminster Avenue overpass or the Santa Ana River Bridge would be exposed to vibration levels exceeding those listed in Table M of the Supplemental Noise and Vibration Analysis, therefore the design modifications do not increase the seventy of vibration impacts nor introduce new vibration impacts not previously analyzed. The residences located adjacent to the Santa Ana River Bridge would be exposed to vibration levels of up to 0.32 PPV, exceeding the 0.2 PPV threshold for standard residential construction. The Old Pacific Electric Santa Ana River Bridge would be exposed to vibration levels of up to 0.23 PPV, exceeding the 0.12 PPV threshold for historic structures. However, these levels are based on the use of impact pile drivers. Section 3.16.2.3 of the EIR included the following best management practices (BMPs) for bridge construction vibration: • Noise and Vibration Control Plan will be developed and implemented prior to construction that will include the following best management practices to minimize exposure to high levels of noise and vibration and ensure compliance with construction noise and vibration criteria listed in the FTA Transit Noise and Vibration Impact Assessment guidance document. This includes ensuring that vibration levels at historic structures do not exceed 0.12 inches per second peak particle velocity. • Where pile -driving operations are required, vibratory pile driving or pre -drilled pile insertion techniques shall be used whenever possible, rather than impact pile driving. Although perceptible at the residences these vibration levels would not exceed FTA's vibration damage criteria. The 2012 Noise and Vibration Technical Report (URS) determined the following distances for potential for vibration impacts due to the use of a piece of equipment such as a vibratory roller during construction: • Building damage to residential structure — 26 Feet • Building damage to institutional structure — 15 Feet 121P age 1170726.1