Reso PC16-23 PC 0116 Reso CEQA - Sandpiper

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Section 4.0 — Environmental Setting and Discussion of Irn pacts The City's noise standards are contained in the General Plan and the Municipal Code. Per the General Plan, the maximum noise level considered normally acceptable for the siting of residential uses within the City is 55 dBA (refer to Table 4.12-1). A three dBA increase is considered the minimum increase that is perceptible to the human ear. Typically, permanent, project -generated noise level increases of three dBA Ldn or greater are considered significant where exterior noise levels will exceed the normally acceptable noise level standard with the project. Where noise levels remain at or below the normally acceptable noise level standard with the project, a noise level increase of five dBA Ldn or greater is considered significant. The City regulates noise in the Noise Ordinance (Chapter 24 of the Redwood City Municipal Code). Section 24.32 establishes that noise generated by construction is prohibited between the hours of 8:00 p.m. and 7:00 a.m. weekdays, or at any time on Saturdays, Sundays, and holidays. In addition, Section 24.31 prohibits noise levels from exceeding 110 dBA for any item of machinery, equipment, or device used during construction in a residential district. Section 24.21 prohibits noise increases of six decibels above local ambient measured noise at any point within a residential district during the hours of 8:00 PM and 8:00 AM. 4.12.3.2 Vibration Thresholds The California Department of Transportation recommends a vibration limit of 0.3 in/see PPV for buildings that are found to be structurally sound but where cosmetic damage is a major concern, such as those buildings in the project area. Therefore, groundborne vibration levels exceeding 0.3 in/sec PPV would have the potential to result in a significant vibration impact. 4.12.3.3 Noise and Vibration Impacts from the Proposed Project (Checklist Questions I — 4) Short -Term Construction Noise The proposed two-story modular classroom building and adjacent restroom would be constructed on the central portion of the project site approximately 130 feet north and 330 feet south of the existing residences south and north of the site, respectively. The proposed modular Kindergarten classroom would be constructed approximately 45 feet south of the nearest residence to the north. The new classroom and Kindergarten building would be modular and, therefore, major components would be constructed off-site prior to being moved and erected on-site. On-site grading and excavation would be necessary to construct building pads and set foundations. The construction will be scheduled to occur during spring and summer school breaks, when the school is mostly unoccupied, and students are not present on the campus. Due to the proposed modular construction process, on-site construction activities would be completed faster than compared to traditional construction techniques and would take approximately five months to complete. The shorter construction period would reduce the duration of the project's construction noise impacts. As shown in Table 4.12-2, maximum noise levels from construction equipment at a distance of 45 feet are all below 90 dBA, except for pile drivers. The proposed project would not require the use of pile drivers; therefore, construction equipment noise levels would not exceed the City's 110 dBA noise limit at the nearest residential property. City of Redwood City 75 Initial Study/Mitigated Negative Declaration Sandpiper Elementary School Facilities Expansion November 2016