Reso PC17-07 0032 PC Reso Approving CEQA - 860 Charter St

Browse Search

LSA ASSOCIATES, INC. SEPTEMBER 2016 ROCKETSHIP REDWOOD CITY ELEMENTARY SCHOOL PROJECT INITIAL STUDY/ MITIGATED NEGATIVE DECLARATION P:\RWC1401B Rocketship School\PRODUCTS\IS-MND\Public\Rocketship Public Review 09-29-16.docx (09/29/16) PUBLIC REVIEW DRAFT 73 departing from the project site, especially during the demolition and site preparation phase of construction. The second type of short-term noise impact is related to the noise generated by heavy equipment operating on the project site. Construction is performed in discrete steps, each of which has its own mix of equipment and, consequently, its own noise characteristics. These various sequential phases would change the character of the noise generated on the site and, therefore, the noise levels surrounding the site as construction progresses. Despite the variety in the type and size of construction equipment, similarities in the dominant noise sources and patterns of operation allow construction-related noise ranges to be categorized by work phase. Table 5 lists typical construction equipment noise levels recommended for noise impact assessments, based on a distance of 50 feet between the equipment and a noise receptor. Demolition and construction activities at the project site are expected to require the use of earthmovers such as bulldozers and scrapers, loaders and graders, water trucks, and haul trucks. As shown in Table 5, the typical maximum noise level generated by each bulldozer on the project site is assumed to be 85 dBA Lmax102 at 50 feet from the operating earthmover. The maximum noise level generated by hydraulic backhoes is approxi- mately 86 dBA Lmax at 50 feet. The maximum noise level generated by haul trucks is approximately 88 dBA Lmax at 50 feet from these vehicles operating at full power. Pile drivers would not be used for construction of this project. Each doubling of the sound sources with equal strength would increase the noise level by 3 dBA. Assuming each piece of construc- tion equipment operates at some distance apart from the other equipment, the worst- case combined noise level at the nearest uses to the site during this phase of construction would be 91 dBA Lmax at 50 feet from the operating equipment. The nearest existing sensitive receivers in the vicinity of the project site are the residences located approximately 400 feet south of the project site. At this distance, construction- related noise levels from the use of heavy construction equipment would be expected to attenuate to approximately 73 dBA Lmax, which is well below the City’s 110 dBA noise ordinance threshold. Therefore, the project would not result in a significant noise impact related to construction noise. 102 Lmax is the maximum A-weighted sound levels measured on a sound level meter, during a designated time interval, using fast time averaging. Table 5: Typical Construction Equipment Maximum Noise Levels, Lmax Type of Equipment Range of Maximum Sound Levels (dBA at 50 feet) Suggested Maximum Sound Levels for Analysis (dBA at 50 feet) Pile Drivers 81 to 96 93 Rock Drills 83 to 99 96 Jackhammers 75 to 85 82 Pneumatic Tools 78 to 88 85 Pumps 74 to 84 80 Scrapers 83 to 91 87 Haul Trucks 83 to 94 88 Cranes 79 to 86 82 Portable Generators 71 to 87 80 Rollers 75 to 82 80 Dozers 77 to 90 85 Tractors 77 to 82 80 Front-End Loaders 77 to 90 86 Hydraulic Backhoe 81 to 90 86 Hydraulic Excavators 81 to 90 86 Graders 79 to 89 86 Air Compressors 76 to 89 86 Trucks 81 to 87 86 Source: Bolt, Beranek & Newman, 1987. Noise Control for Buildings and Manufacturing Plants. ATTY/RESO.0032/PC RESO APPROVING CEQA - 860 CHARTER ST. EXHIBIT A REV: 06-15-17 PR Page 81 of 124