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Administrative Draft Environmental Impact Report Gill Medical Center Project Excessive groundborne vibration impacts result from continuously occurring vibration levels. Increases in groundborne vibration levels attributable to the Project would be primarily associated with short-term construction-related activities. Construction on the Project site would have the potential to result in varying degrees of temporary groundborne vibration, depending on the specific construction equipment used and the operations involved. Ground vibration generated by construction equipment spreads through the ground and diminishes in magnitude with increases in distance. Construction-related ground vibration is normally associated with impact equipment such as pile drivers, jackhammers, and the operation of some heavy-duty construction equipment, such as dozers and trucks. It is noted that pile drivers would not be necessary during Project construction.Vibration decreases rapidly with distance and it is acknowledged that construction activities would occur throughout the Project site and would not be concentrated at the point closest to sensitive receptors. Groundborne vibration levels associated with construction equipment are summarized in Table 4.15-14. Table 4.15-14.Representative Vibration Source Levels for Construction Equipment Equipment Type Peak Particle Velocity at 25 Feet(inches per second) Large Bulldozer 0.089 Caisson Drilling 0.089 Loaded Trucks 0.076 Hoe Ram 0.089 Jackhammer 0.035 Small Bulldozer/Tractor 0.003 Source: FTA 2018;Caltrans 2020 The County's Noise Policy of the General Plan, Goal PHS-9.4, states that the County shall require construction projects anticipated to generate a significant amount of vibration to ensure acceptable interior vibration levels at nearby vibration-sensitive uses based on FTA criteria. For the purpose of this analysis, the FTA's recommendation of 0.2 inches per second peak particle velocity with respect to the prevention of structural damage for non-engineered timber and masonry buildings is used as a threshold. This is also the level at which vibrations may begin to annoy people in buildings. It is acknowledged that construction activities would occur throughout the Project site and would not be concentrated at the point closest to the nearest structure. Consistent with FTA recommendations for calculating construction vibration, construction vibration was measured from the center of the Project site (FTA 2018).The nearest structure of concern is located on the adjacent residential property approximately 330 feet distant. Based on the representative vibration levels presented for various construction equipment types in Table 4.15-14 and the construction vibration assessment methodology published by the FTA (2018), it is Noise 4.15-33 October 2021