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WILSON IHRIG <br />Arroyo Lago Residential Project <br />Review and Comment on Noise Report <br /> <br /> <br />Page 4 <br /> <br />Figure 1: Project Site and Off-Site Infrastructure <br />Construction Prediction Contains Errors <br />The DEIR states that construction noise levels of 78 dBA were predicted 35 feet from the “acoustic <br />center of construction activity” and include shielding from the existing 6-foot-high sound wall located <br />along the western boundary [DEIR, pg. 3.12-19]. The DEIR compares this to the Federal Transit <br />Administration Noise Assessment Manual (FTA Manual) construction noise threshold of 80 dBA. <br />Appendix H shows that the calculations for grading and site preparation used 35 feet for the grader and <br />85 feet for the rest of the equipment [App. H, pg. 3]. If the predictions used the distance specified in the <br />DEIR, construction noise levels at nearby residences would be over the FTA 80 dBA threshold, as shown <br />in Table 1. Further, the report provides no evidence in the form of measurement data, or even photos of <br />the walls, showing that the existing barriers can provide 8 dB of shielding. Therefore, construction levels <br />may be higher than those shown below. The Project should address this error. <br />Table 1: Corrected Estimated Construction Noise Levels for Grading and Site Preparation <br />Equipment <br />Lmax at <br />50 ft. <br />(dBA) <br />Usage <br />(%) <br />Distance <br />(feet) <br />Shielding <br />(dB) Ground <br />Leq at <br />Residence <br />(dBA) <br />Over <br />Ambient <br />(dBA)1 <br />grader 85 40 35 8 1 78 <br />excavator 85 40 35 8 1 78 <br />front end loader 80 40 35 8 1 73 <br />backhoe 80 40 35 8 1 73 <br />TOTAL: 82 23 <br />PARCEL B <br />(future <br />development)