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<br />16 <br /> <br />around the perimeter of the fields and tennis court. The proposed project would not require pile <br />driving, which can cause excessive vibration. <br /> <br />For structural damage, the California Department of Transportation recommends a vibration limit of <br />0.5 in/sec PPV for buildings structurally sound and designed to modern en gineering standards, 0.3 <br />in/sec PPV for buildings that are found to be structurally sound but where structural damage is a <br />major concern, and a conservative limit of 0.08 in/sec PPV for ancient buildings or buildings that <br />are documented to be structurally weakened. No ancient buildings or buildings that are documented <br />to be structurally weakened adjoin the project site. Therefore, groundborne vibration levels <br />exceeding 0.3 in/sec PPV would have the potential to result in a significant vibration impact. <br /> <br />Table 5 presents typical vibration levels that could be expected from construction equipment at a <br />distance of 25 feet. Project construction activities, such as drilling, the use of jackhammers, rock <br />drills and other high-power or vibratory tools, and rolling stock equipment (tracked vehicles, <br />compactors, etc.) may generate substantial vibration in the immediate vicinity. Jackhammers <br />typically generate vibration levels of 0.035 in/sec PPV, and drilling typically generates vibration <br />levels of 0.09 in/sec PPV at a distance of 25 feet. Vibration levels would vary depending on soil <br />conditions, construction methods, and equipment used. The adjacent single-family residences range <br />from 40 to 430 feet from the project site; at these distances, vibration levels would be expected to be <br />0.2 in/sec PPV or less, below the 0.3 in/sec PPV significance threshold. Vibration generated by <br />construction activities near the common property line would at times be perceptible, however, <br />would not be expected to result in “architectural” damage to these buildings. This is a less-than- <br />significant impact. <br /> <br />TABLE 5 Vibration Source Levels for Construction Equipment <br />Equipment PPV at 25 ft. (in/sec) Approximate Lv <br />at 25 ft. (VdB) <br />Pile Driver (Impact) upper range 1.158 112 <br />typical 0.644 104 <br />Pile Driver (Sonic) upper range 0.734 105 <br />typical 0.170 93 <br />Clam shovel drop 0.202 94 <br />Hydromill (slurry wall) in soil 0.008 66 <br />in rock 0.017 75 <br />Vibratory Roller 0.210 94 <br />Hoe Ram 0.089 87 <br />Large bulldozer 0.089 87 <br />Caisson drilling 0.089 87 <br />Loaded trucks 0.076 86 <br />Jackhammer 0.035 79 <br />Small bulldozer 0.003 58 <br />Source: Transit Noise and Vibration Impact Assessment, United States Department of Transportation, Office of <br />Planning and Environment, Federal Transit Administration, May 2006. <br /> <br />Mitigation Measure 2: None required. <br />8.A. - Page 132