Agenda Packet_2025-12-02 - Laserfiche WebLink

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City of Santa Ana California Environmental Quality Act Initial Study/Mitigated Negative Declaration - 37 - ➢ Sonic Pile Driving - At the upper range reference vibration for the sonic/vibratory pile driver, the risk for damage to nearby buildings begins when the equipment is 32 feet or closer to the structure. The nearest piling is expected to be 20 feet from the closest structure, so vibration limit exceedances would remain with use of a vibratory pile driver. ➢ Drilled Piles - Noise emission levels from bored/drilled pilling methods are approximately 15 dB lower and peak particle velocity (PPV) levels may be more than 15 times lower than those due to traditional impact piling. The use of these methods will eliminate the vibration impacts of all receivers. These methods will also substantially reduce the noise impacts and in most cases they will also be eliminated, with the use of a suitable noise barrier. ➢ Hammer Energy - A recommended way to reduce PPV is to lower the hammer energy since there is a direct relationship between hammer energy and the resultant ground vibration. Ground PPV generally follows a square root relationship with hammer energy (i.e. PPV ~ √Hammer Ene rgy). The degree of hammer energy reduction must be balanced against the likelihood/severity of expected exceedances, increase in total driving time, and ability to drive to required friction tolerances. ➢ Vibration Monitoring - It is recommended that vibration monitoring be conducted at any building where equipment is operating closer than the limits noted in Table 3-4. Table 3-4 Construction Equipment Vibration Reference Levels Equipment Description Minimum Separation Distance Pile Driver (impact) 52 feet Pile Driver (Vibratory) 32 feet Vibratory Roller 14 feet Compactor (Ground) 13 feet Large Bulldozer 8 feet City Council 15 – 90 12/2/2025