FULL PACKET_2011-10-17 - Laserfiche WebLink

Home Browse Search

BENDER READY -MIX CONCRETE MANUFACTURING PROJECT Initial Study /Mitigated Negative Declaration Sensitive uses surrounding the project site include multi - family residential uses immediately to the west and single - family uses approximately 600 feet to the north. Uses to the east and south include industrial /manufacturing uses, which are not considered to be sensitive. As noted in Table 4.12 -5, construction noise associated with the proposed project would not expose surrounding sensitive uses to construction noise levels in excess of the Speech Interference Criteria (65 dBA) during construction, with the exception of demolition activities. However, demolition would only occur for one day, between the allowable construction hours, and would not be considered a significant impact. It should be noted that construction noise levels perceived by residences to the east would typically be lower than the levels presented in Table 4.12 -5, as the model does not account for attenuation due to the grade difference between the residences and the project site. Additionally, construction activities conducted within the allowable hours are exempt from the City's noise standards. Therefore, with adherence to the noise standards of the Municipal Code, construction noise impacts would be less than significant. Mitigation Measures: No mitigation is required. b) Exposure of persons to or generation of excessive ground -borne vibration or groundborne noise levels? Less Than Si_anifrcant Impact Project construction can generate varying degrees of ground -borne vibration, depending on the construction procedure and the construction equipment used. Operation of construction equipment generates vibrations that spread through the ground and diminish in amplitude with distance from the source. The effect on buildings located in the vicinity of the construction site often varies depending on soil type, ground strata, and construction characteristics of the receiver building(s). The results from vibration can range from no perceptible effects at the lowest vibration levels, to low rumbling sounds and perceptible vibration at moderate levels, to slight damage at the highest levels. Ground -bome vibrations from construction activities rarely reach levels that damage structures. The Federal Transit Administration (FTA) has published standard vibration velocities for construction equipment operations. In general, the FTA architectural damage criterion for continuous vibrations (i.e., 0.20 inch /second) appears to be conservative. The types of construction vibration impact include human annoyance and building damage. Human annoyance occurs when construction vibration rises significantly above the threshold of human perception for extended periods of time. Building damage can be cosmetic or structural. Typical vibration produced by construction equipment is illustrated in Table 4.12 -6, Typical Vibration Levels for Construction Equipment. Table 4.12 -6 Typical Vibration Levels for Construction Equipment _zA Loaded trucks LL 0.076 0.015 Small bulldozer 0.003 0.001 Notes: 1. Peak particle ground velocity measured at 25 feet unless noted otherwise. 2. Root mean square amplitude ground velocity in decibels (VdB) referenced to 1 micro - inch /second. Source: Federal Transit Administration, Transit Noise and Vibration Impact Assessment Guidelines, May 2006. JULY 2011 4.12 -6 NOISE 31A-80 1 f n 1 171