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ARROYO LAGO RESIDENTIAL PROJECT ADDENDUM 154 FCS Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/2148/21480036/Addendum/21480036 Arroyo Lago Residential Project Addendum.docx General Plan Noise Element identifies that an increase of 4 dBA over existing ambient conditions is considered a threshold for significance. The proposed project would result in substantially the same mechanical ventilation equipment compared to the County Project albeit with a nominal decrease given the slight reduction in units. Based on noise measurements, ambient noise levels are documented as being 59 dBA CNEL near the southwest portion of the project site, with daytime short-term ambient noise measurements ranging from 45.2 dBA to 57.1 dBA Leq across the site. Based on the proposed site plan, none of the mechanical systems would be located closer to off-site receptors than what was previously analyzed as the reasonable worst-case scenario. The modeled noise level for mechanical equipment was 44 dBA L eq as measured at the exterior of the nearest sensitive receptor. This reasonable worst-case stationary source operational noise level would not result in an increase of more than 4 dBA over documented existing ambient noise conditions identified above and is therefore consistent with the noise performance standard of Program 1.3. Therefore, consistent with the impact conclusions of the Prior FEIR, the proposed project’s mechanical ventilation equipment operational noise impacts would be less than significant. The proposed project’s construction and operational noise impact would continue to be less than significant, and the proposed project would not introduce any new significant impacts or create substantially more severe significant impacts than those previously identified in the Prior FEIR. No additional analysis is required. b) Groundborne Vibration Would the project result in: Generation of excessive groundborne vibration or groundborne noise levels? Prior FEIR Conclusions The Prior FEIR evaluated vibration impacts using FTA criteria because the County does not have any quantitative applicable standards for construction or operational vibration thresholds. As detailed more fully therein, the nearest residences are not expected to experience vibration levels exceeding the thresholds for structural damage or annoyance. Construction equipment such as graders and trucks would operate at distances sufficient to avoid excessive vibration. Therefore, the Prior FEIR concluded that groundborne vibration impacts would be less than significant. (Draft EIR, pp. 3.12-24, 6-17). Proposed Project Analysis and Conclusion Construction Vibration Impacts Pleasanton General Plan Noise Element Program 1.6 requires preparation of a vibration study by a qualified vibration consultant, with a site-specific engineering assessment for any proposed construction project that would require pile driving or similar vibration causing impacts. The assessment would minimize potential vibration impacts through such measures as pre-drilling pile hoses, driving piles hydraulically or enclosing sheet piles with rubber aprons. The City Engineer would review and approve all vibration studies. However, the proposed project would not include use