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TABLE 3.7-1. EXISTING NOISE LEVELS AT THE PROJECT SITE (a) Locations are keyed to monitoring sites shown in Figure 3.7-1. (b) Peak hour derived by adding 1 dBA. (c) Calculated level (peak hour Leq (dBA) + 2 dBA = approximate Ldn). Source: Earth Metrics Incorporated, 1987. The existing 53 dBA Ldn sound level measured at Location 1 is below the 65 dBA Ldn limit which is designated by the Zoning Ordinance for residential areas. Locations 2 and 3 were measured to be above the Zoning Ordinance limit and were measured to be 70 dBA Ldn and 67 dBA Ldn, respectively. At Location 2, the high sound level was due to noise from trucks entering and exiting Tracy Defense Depot and gravel trucks traveling to and from nearby gravel pits. The sound level at Location 3 was also influenced by gravel trucks. In general, heavy trucks, like those used by the nearby gravel excavating companies, generate noise between 70 and 90 dBA at a distance of 50 feet when fully loaded. At the time of the measurements, railroad noise was not experienced. However, based on the noise study conducted for the San Joaquin County Council of Governments, a noise level of 65 dBA is estimated to occur approximately 206 feet from the center of the railroad track (San Joaquin County Council of Governments). IMPACTS. Initial noise impacts of the proposed project would result from construction operations. Project generated motor vehicle noise increases would follow with completion and occupancy of the project. The completed project also would be subject to noise impacts from increased traffic levels in the project area. Construction Noise. Increases in noise levels during the construction activities would occur as a result of direct construction noise in the construction area, and construction truck traffic along the haul routes. The direct construction noise on site would result from construction operations. The construction equipment identified as major sources of noise and typical sound levels (dBA) of this equipment at 50 feet are: dump trucks (88), portable air compressors (81), concrete mixer (truck) (85), jackhammer (88), scraper (88), bulldozer (87), paver (89), generator (76), piledriver (101), rock drill (98), pumps (76), pneumatic tools (85), and backhoes (85) (EPA, 1971). 3.7-3 PEAK HOUR LOCATION DISTANCE FROM CENTER Leq Ldn (a) TIME OF NEAREST LANE Leq(dBA) WBA)(b) (dBA)(c 1 1:11 - 1:31 P.M. 31 feet 50 51 53 2 1:414 - 2:04 P.M. 33 feet 67 68 70 3 2:20 - 2:40 P.M. 31 feet 64 65 67 (a) Locations are keyed to monitoring sites shown in Figure 3.7-1. (b) Peak hour derived by adding 1 dBA. (c) Calculated level (peak hour Leq (dBA) + 2 dBA = approximate Ldn). Source: Earth Metrics Incorporated, 1987. The existing 53 dBA Ldn sound level measured at Location 1 is below the 65 dBA Ldn limit which is designated by the Zoning Ordinance for residential areas. Locations 2 and 3 were measured to be above the Zoning Ordinance limit and were measured to be 70 dBA Ldn and 67 dBA Ldn, respectively. At Location 2, the high sound level was due to noise from trucks entering and exiting Tracy Defense Depot and gravel trucks traveling to and from nearby gravel pits. The sound level at Location 3 was also influenced by gravel trucks. In general, heavy trucks, like those used by the nearby gravel excavating companies, generate noise between 70 and 90 dBA at a distance of 50 feet when fully loaded. At the time of the measurements, railroad noise was not experienced. However, based on the noise study conducted for the San Joaquin County Council of Governments, a noise level of 65 dBA is estimated to occur approximately 206 feet from the center of the railroad track (San Joaquin County Council of Governments). IMPACTS. Initial noise impacts of the proposed project would result from construction operations. Project generated motor vehicle noise increases would follow with completion and occupancy of the project. The completed project also would be subject to noise impacts from increased traffic levels in the project area. Construction Noise. Increases in noise levels during the construction activities would occur as a result of direct construction noise in the construction area, and construction truck traffic along the haul routes. The direct construction noise on site would result from construction operations. The construction equipment identified as major sources of noise and typical sound levels (dBA) of this equipment at 50 feet are: dump trucks (88), portable air compressors (81), concrete mixer (truck) (85), jackhammer (88), scraper (88), bulldozer (87), paver (89), generator (76), piledriver (101), rock drill (98), pumps (76), pneumatic tools (85), and backhoes (85) (EPA, 1971). 3.7-3