Reso PC16-23 PC 0116 Reso CEQA - Sandpiper

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Section 4.0—Envirownental Setting and Discussion oflmpacts to interfere with the enjoyment of life; these two concerns are evaluated against different vibration limits. Studies have shown that the threshold of perception for average persons is in the range of 0.008 to 0.012 in/See PPV.28 Human perception to vibration varies with the individual and is a function of physical setting and the type of vibration. Persons exposed to elevated ambient vibration levels, such as people in an urban environment, may tolerate a higher vibration level. Structural damage can be classified as cosmetic (e.g., minor cracking of building elements), or may threaten the integrity of the building. Safe vibration limits that can be applied to assess the potential for damaging a structure vary by researcher and there is no general consensus as to what amount of vibration may pose a threat for structural damage to the building. Construction -induced vibration that can be detrimental to a building is very rare and has only been observed in instances where the structure is at a high state of disrepair and the construction activity occurs immediately adjacent to the structure. The California Department of Transportation recommends a vibration limit of 0.3 in/sec PPV for buildings that are found to be structurally sound but where cosmetic damage is a major concern. Therefore, groundborne vibration levels exceeding 0.3 in/sec PPV would have the potential to result in a significant vibration impact. 4.12.1.3 Applicable Plans, Policies, and Regulations Redwood City General Plan The City's noise/land use compatibility guidelines are included in the Public Safety chapter of the General Plan. Based on the City's General Plan, Table 4.12-1 shows the noise levels considered consistent with the land uses located on and adjacent to the project site. For public facilities/schools, such as those located existing project site, outdoor noise levels of up to 55 decibels are normally acceptable and up to 70 decibels are permitted only after a detailed analysis of noise reduction requirements are made. For residential uses, such as those located adjacent to the project site, outdoor noise levels of up to 55 decibels are normally acceptable and up to 75 decibels are permitted only after a detailed analysis of noise reduction requirements are made. Table 4.12-1: Redwood City Noise/Land Use Compatibility Guidelines Noise and Land Use Compatibility (Ldn) Land Use 55 60 65 70 75 80 85 Residential — Medium/Medium High Density Public Facilities/Schools Normally Acceptable Conditionally Acceptable Normally Unacceptable Clearly Unacceptable 28 Caltrans. Transportation and Construction cribration Guidance Manual. September 2013. City of Redwood City 72 Initial Study/Mitigated Negative Declaration Sandpiper Elementary School Facilities Expansion November 2016