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INITIAL STDDV/MITIGATED NEGATIVE DECLARATION <br />MAY 2020 <br />FAIRVIEW BRIDGE REPLACE MENT AND STREET IMPROVEMENTS L S A <br />(9TH STREET TO 16TH STREET) PROJECT <br />SANTA ANAL CALL EORNIA <br />Table 3.13.13 shows the PPV and VdB values at 25 ft from a construction vibration source. As <br />shown in Table 3.13.D, bulldozers and other heavy -tracked construction equipment (except for <br />pile drivers and vibratory rollers) generate approximately 87 VdB of groundborne vibration <br />when measured at 25 ft, based on the Transit Noise and Vibration Impact Assessment. At this <br />level, groundborne vibration would result in potential annoyance to residents and workers but <br />would not cause any damage to the buildings. <br />Table 3.13.D: Vibration Source Amplitudes for Construction Equipment <br />Equipment <br />Reference PPV/Lv at 25 feet <br />PPV (in/sec) <br />Lv (VdB)1 <br />Pile Driver (Impact), Typical <br />0.644 <br />104 <br />Pile Driver (Sonic), Typical <br />0.170 <br />93 <br />Vibratory Roller <br />0.210 <br />94 <br />Hoe Ram <br />0.089 <br />87 <br />Large Bulldozer <br />0.089 <br />87 <br />Caisson Drilling <br />0.089 <br />87 <br />Loaded Trucks <br />0.076 <br />86 <br />Jackhammer <br />0.035 <br />79 <br />Small Bulldozer <br />0.003 <br />58 <br />Source: Transit Noise and Vibration Impact Assessment Manual (FTA 2018). <br />1 RMS in VdB is 1 µin/sec. <br />µin/sec= micro -inches per second PPV= peak particle velocity <br />FTA= United States Federal Transit RMS=root-mean-square <br />Administration VdB = vibration velocity decibels <br />in/sec = inches per second <br />Lv = velocity in decibels <br />Construction vibration, similar to vibration from other sources, would not have any significant <br />effects on outdoor activities (e.g., those outside of residences and commercial/office buildings <br />in the Project vicinity). Outdoor site preparation for the proposed Project is expected to include <br />the use of bulldozers and loaded trucks. The greatest levels of vibration are anticipated to occur <br />during the site preparation phase. All other phases are expected to result in lower vibration <br />levels. The distance to the nearest buildings for vibration impact analysis is measured between <br />the nearest off -site buildings and the Project boundary (assuming the construction equipment <br />would be used at or near the Project boundary) because vibration impacts occur normally within <br />the buildings. The formula for vibration transmission is provided below: <br />LvdB (D) = LvdB (25 ft) — 30 Log (D/25) <br />PPVequip= PPVref X (25/D)1.5 <br />For typical construction activity, the equipment with the highest vibration generation potential <br />is the large bulldozer, which would generate 87 VdB at 25 ft. The closest residences are located <br />approximately 50 ft from the Project construction areas. Due to distance attenuation, the <br />closest residences would experience vibration levels of up to 78 VdB (0.031 in/sec PPV), which is <br />below the FTA threshold of 94 VdB (0.2 in/sec PPV) for building damage. Although construction <br />vibration levels at the adjacent land uses would have the potential to result in annoyance, these <br />vibration levels would no longer occur once construction of the proposed Project is completed. <br />R:\WKE1702\ISMND\Fina1 ISMND\Fairview Street Bridge Final ISM,76SE3 117 3-83 <br />