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 the human ear is most sensitive. The A -weighted sound level is the basis for a number of various sound level metrics, including the day/night sound level (Ldn) and the Community Noise Equivalent Level (CNEL), both of which represent how humans are more sensitive to sound at night. In addition, the equivalent continuous sound level (Leq) is the average sound energy of time -varying noise over a sample period and the Lmax is the maximum instantaneous noise level occurring over a sample period. Groundborne vibration consists of rapidly fluctuating motion through a solid medium, specifically the ground, which has an average motion of zero and in which the motion's amplitude can be described in terms of displacement, velocity, or acceleration. The effects of groundborne vibration typically only cause a nuisance to people, but in extreme cases, excessive groundborne vibration has the potential to cause structural damage to buildings. Although groundborne vibration can be felt outdoors, it is typically only an annoyance to people indoors where the associated effects of the shaking of a building can be notable. Groundborne noise is an effect of groundborne vibration and only exists indoors, since it is produced from noise radiated from the motion of the walls and floors of a room, and may also consist of the rattling of windows or dishes on shelves. Several different methods are used to quantify vibration amplitude such as the maximum instantaneous peak in the vibrations velocity, which is known as the peak particle velocity (PPV) or the root mean square (rms) amplitude of the vibration velocity. Because of the typically small amplitudes of vibrations, vibration velocity is often expressed in decibels —denoted as LV—and is based on the reference quantity of 1 microinch per second. To distinguish vibration levels from noise levels, the unit is written as WdB." Although groundborne vibration can be felt outdoors, it is typically only an annoyance to people indoors where the associated effects of the shaking of a building can be notable. When assessing annoyance from groundborne vibration, vibration is typically expressed as rms velocity in units of decibels of 1 microinch per second, with the unit written in VdB. Typically, developed areas are continuously affected by vibration velocities of 50 VdB or lower. Human perception to vibration starts at levels as low as 67 VdB. Annoyance due to vibration in residential settings starts at approximately 70 VdB. Existing Conditions The dominant noise sources in the project vicinity include traffic on local roadways, primarily from traffic on Santa Ana Freeway, which runs along the northern and eastern boundary of the project site. Regulatory Framework The project site is located in the City of Santa Ana and this analysis was performed using the City's noise regulations. The City addresses noise in its policies and regulations of the Noise Element of its General Plan and in Article VI Noise Control of City's Code of Ordinances. These policies and regulations are summarized below. FCS 77 Https://adecinnovations.sharepoint.com/sites/PubiicationsSite/Shared Documents/Publications/Client(PN-JN)/D327/03270D47/ISMND/0327D047 Santa Ana Rezone Project ISMND.docx