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WILSON IHRIG Arroyo Lago Residential Project Review and Comment on Noise Report Page 5 Potentially Significant Construction Noise Impacts As stated above, the DEIR compares estimated construction noise levels to the FTA Manual threshold of 80 dBA. The cited FTA document is a guidance document, and it discourages projects against using its absolute noise criteria values without consideration of local conditions [FTA page 179, see Figure 1 below]. Figure 2: FTA Noise and Vibration Impact Assessment, Section on Construction Noise and Vibration (page 179) California Environmental Quality Act Guidelines cited in the DEIR state that impacts to noise would be significant if the proposed project would result in “generation of a substantial temporary or permanent increase in ambient noise levels” [DEIR, pg. 3.12-18]. The DEIR lacks a significance threshold for “substantial increase” for Project noise. As shown in Table 1 above, corrected estimated construction levels are 23 dBA above the measured ambient CNEL at LT-1. The Project must properly evaluate construction noise impacts, including the noise increase over ambient levels at sensitive receptor locations. If the increase is significant the Project must properly evaluate mitigation measures to reduce the impacts to less than significant. Baseline Noise is Not Properly Established The manner in which the DEIR has determined the existing noise environment at sensitive receivers is unsupported. Three short-term measurements and one long-term measurement were conducted within the Project site. The report provides no evidence or discussion that these measurements are representative of levels at sensitive receivers near the Project. Table 3.12-5 of the DEIR describes the short-term locations (approximated in Figure 2 below), but the report does not provide a figure showing the measurements (Appendix H includes a sketch of ST-1). The DIER states that dominant noise sources in the project vicinity are vehicular traffic on Busch Road, the Fire Department training facility, trucks from industrial use to the south, and the Pleasanton Garbage Station and that the long-term measurement was taken on the southwest corner of the site, approximately 20 feet off Busch Road [DEIR, pg. 3.12-9]. The report does not discuss how the measurement locations relate to sensitive receivers adjacent to the site. As shown in Figure 1, the residences along Chatham Place are 835 feet from Busch Road. The Fire Department training facility is adjacent to the homes, but the activities from the facility are not well documented. Ambient levels at residences are likely between levels at ST-1 (45 dBA) and LT-1 / ST-3 (59 CNEL / 55 dBA).