2017-046 - Approving Addendum Nos. 1 and 2

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0� OCTA I Santa Ana/Garden Grove Fixed Guideway Project Noise and Vibration Technical Analysis Re-evaluation in Support of Minor Design Modifications Table M: Construction Vibration Damage Criteria Building Category I PPV (in/sec) Approximate Lv Lv: Root mean square (RMS) velocity in decibels (VdB) re 1 micro-inch/second Construction of the proposed project may require pile driving and has the potential to result in temporary vibration impacts to structures and humans. 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. Although there would continue to be no sensitive locations within 100 feet of the Westminster Avenue overpass, with the proposed modified alignment pile driving activities associated with the Santa Ana River Bridge could occur within 50 feet of the historic Old Pacific Electric Santa Ana River Bridge and within 40 feet of residences and other structures. 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 May 2014 EA/DEIR 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. FTA estimates that vibration/sonic pile driving generates PPV vibration levels of 0.17 in/sec at a distance of 25 feet. Distance attenuation would reduce this level to 0.08 in/sec at the closest residences and 0.06 in/sec at the Old Pacific Electric Santa Ana River Bridge. Although perceptible at the residences these vibration levels would not exceed FTA's vibration damage criteria. In addition to pile driving, a road roller (sometimes called a roller -compactor or just roller) is a compactor type engineering vehicle that is often used to compact soil, gravel, concrete, or asphalt in the construction of roads and foundations. Road rollers use the weight of the vehicle to compress the surface being rolled (static) or use mechanical advantage (vibrating). While smaller in size as compared to the pile driving equipment, a vibratory roller would potentially be employed along the length of the streetcar alignment. 13