Item 22 - Public Hearing Ordinance Second Reading - General Plan Amendment, Zoo Overflow Parking Rezone

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SANTA ANA REZONE PROJECT INITIAL STUDY/MITIGATED NEGATIVE DECLARATION This section analyzes both construction and operational groundborne vibration and noise impacts. Groundborne vibrations consist of rapidly fluctuating motions within the ground that have an average motion of zero. Vibrating objects in contact with the ground radiate vibration waves through various soil and rock strata to the foundations of nearby buildings. Groundborne noise is generated when vibrating building components radiate sound, or noise, generated by groundborne vibration. In general, if groundborne vibration levels do not exceed levels considered to be perceptible, then groundborne noise levels would not be perceptible in most interior environments. Therefore, this analysis focuses on determining exceedances of groundborne vibration levels. Short-term Construction Vibration Impacts Of the variety of equipment that would be used during construction, small vibratory rollers would produce the greatest groundborne vibration levels. Impact equipment such as pile drivers would not be used during construction of this project. Large vibratory rollers produce groundborne vibration levels ranging up to 0.201 inch per second (in/sec) PPV at 25 feet from the operating equipment. The nearest building structure to the project construction footprint is the cement block structure located east of the project site. This structure is located approximately 40 feet from the nearest construction footprint where small vibratory rollers would potentially operate. At this distance, groundborne vibration levels would range up to 0.099 in/sec PPV from operation of the types of equipment that would produce the highest vibration levels. This is below the FTA's construction vibration damage criteria of 0.2 in/sec PPV for this type of structure, a building of nonengineered timber and masonry construction. As a result, construction of the proposed project would not expose nearby buildings to groundborne vibration levels in excess of their applicable FTA damage criteria and this impact would be less than significant. Operational Vibration Impacts Implementation of the project would not include any new permanent sources that would expose persons in the project vicinity to groundborne vibration levels that could be perceptible without instruments at any existing sensitive land use in the project vicinity. Additionally, there are no active sources of groundborne vibration in the project vicinity that would produce vibration levels that would be perceptible without instruments within the project site. Therefore, there would be no impact related to operational groundborne vibration. c) For a project located within the vicinity of a private airstrip or an airport land use plan or, where such a plan has not been adopted, within two miles of a public airport or public use airport, would the project expose people residing or working in the project area to excessive noise levels? No impact. The airport nearest to the project site is John Wayne International Airport, located approximately 4.28 miles south of the project site. While aircraft noise is occasionally audible at the project site, because of the distance from the airport and the orientation of runways and flight patterns, the project site does not lie within the established noise contours of John Wayne International Airport and is not close enough to any other airports to be affected by aviation noise. Furthermore, the proposed project is not a noise -sensitive land use; it is a parking lot that would not FCS 83 Https://adecinnovations.sharepoint.com/sites/PubiicationsSite/Shared Documents/Publications/Client(PN-JN)/D327/03270D47/ISMND/0327D047 Santa Ana Rezone Project ISMND.docx