NS-3092 - Zone Change for 1801 East Chestut Ave

Home Browse Search

SANTA ANA REZONE PROJECT INITIAL STUDYIMITIGATED NEGATIVE DECLARATION center of construction activity where multiple pieces of heavy construction equipment would potentially operate simultaneously at the project site. This was measured from the project boundary line to the residential property line to provide a conservative approach.At this distance, with minimal shielding from an existing concrete wall, worst-case construction noise levels could range up to approximately 72 dBA Lmax, intermittently, and could have an hourly average of up to 66 dBA Leq at the fagade of the nearest single-family residential home. The calculation spreadsheet with detailed modeling assumptions is provided in Appendix D. These reasonable worst-case construction noise levels would only occur periodically throughout the day as construction equipment operates along the nearest project boundaries.Additionally, these noise levels would drop off at a rate of 6 dBA per doubling of distance as the equipment moves over the project site. Therefore, the calculated reasonable worst-case 8-hour average noise level for construction assuming construction equipment moves over the project site would be 61 dBA Leq(8-hour) as measured at the nearest residential receptor. These calculated conservative worst-case construction noise levels would not exceed the FTA's threshold of 80 dBA Leq(B-hour)as measured at the nearest residential receptors. Furthermore, the proposed project will be required to comply with the City's permissible hours for construction (7:00 a.m. and 8:00 p.m. Monday through Saturday; construction activities are prohibited on Sundays and federal holidays)which would ensure that construction noise would not result in a substantial increase in nighttime noise levels in the project vicinity. Therefore, the analysis demonstrates that the proposed project's construction noise would not result in a substantial increase in excess of established standards and the impact would be less than significant. OperationaUStationary Source Noise Impacts Less than significant impact.A significant impact would occur if operational noise levels generated by stationary noise sources at the proposed project site would result in a substantial permanent increase in ambient noise levels in excess of any of the noise performance thresholds established in the City Municipal Code. The City has established an exterior noise limit of 55 dBA Leq hourly average during daytime hours and a noise limit of 50 dBA Leq hourly average during nighttime hours for receiving residential land uses. However, the City notes that if the existing ambient noise level exceeds these standards, the ambient noise level shall be considered the standard. The proposed project would include parking lot activities, similar to the project site's existing parking lot activities. Parking Lot Activities Typical parking lot activities include people conversing, doors shutting, and vehicles idling, which generate noise levels ranging from approximately 60 dBA to 70 dBA Lmax at 50 feet. These activities are expected to occur sporadically throughout the day as visitors and staff arrive and leave parking lot areas at the project site. FCS [(�� 81 Https://ad¢cinnovatio-ns.sharep9int.t9mfsil¢5/Publicatiuns5itefSba red Document,/PubHi t10n5/C1ient(PN-JN)/03 7 7/0 3 7 7004 7/13MN0/03Z7004752nte And Rezone P,,Qrdkowce No. NS-3092 Page 93 of 118