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Noise from localized point sources(such as construction sites)typically decreases by approximately 6 dBA with each doubling of distance between the source and receptor.Given this noise attenuation rate and assuming no ` noise shielding from either natural or human-made features(e.g.,trees,buildings,fences),noise-sensitive uses (residential)within approximately 900 feet of construction sites could experience maximum instantaneous exterior noise levels of greater than 65 dBA when on-site construction-related noise levels exceed approximately 90 dBA(at a distance of 50 feet). As indicated above,project construction activities could result in instantaneous exterior noise levels greater than 65 dBA within approximately 900 feet of the loudest anticipated construction operations.However,because daytime construction activities are exempt from County noise standards per Section 1025.9(c)(3)of the County's Development Title, a less-than-significant impact would occur with respect to daytime construction noise. Nighttime construction activities under College Park could exceed the applicable L.,and Ld„construction-noise thresholds at nearby existing residential dwellings, including at Grant Line Village,the four residences in the central portion of the project site,the one residence on the south side of Grant Line Road between Mountain House Parkway and the Alameda County line,the seven residences on the north side of Grant Line Road between Mountain House Parkway and the Alameda County line,and the four residences on the east side of Mountain House Parkway between the I-205 interchange and Mascot Road(Figure 4.13-2).Nighttime construction activities associated with the College Park project could also exceed the applicable L.,and Ldn thresholds at proposed on-site residential dwellings.Therefore, a significant impact could occur. Mitigation Measure 4.13-1: Nois"eneration of Temporary Construction Noise. ► Limit project construction activities to the hours between 6:00 a.m. and 9:00 p.m. ► Comply with the San Joaquin County Development Title for all construction activities. Equip all construction vehicles or equipment,fixed or mobile,with properly operating and maintained mufflers and acoustical shields or shrouds,in accordance with manufacturers' recommendations. ► Arrange all construction equipment and truck routes to minimize travel adjacent to occupied residences. Locate stationary construction equipment and staging areas as far as possible from sensitive receptors. Temporary acoustic barriers may be installed around stationary equipment, if necessary. Implementation of the above mitigation measure would reduce temporary construction-related noise impacts on sensitve receptors to a less-than-significant level. IMPACT Noise--Generation of New Stationary-Source Noise. The proposed project would result in new 4.13-2 stationary-source noise(specifically, noise from commercial/of6celndustrial uses and landscape maintenance)that could exceed applicable County noise standards at existing and proposed nearby noise- sensitive land uses.A significant impact could occur. The proposed College Park land use concept(see Figure 3-6b in Chapter 3,"Project Description") features a mix of land uses,including residential,neighborhood commercial,commercial,office, limited industrial,schools, community parks, and community college campus uses.The sources and levels of stationary-source noise typically associated with these land uses are discussed below. Residential Land Uses Occupancy of proposed residential dwellings would expose nearby residences,including occupants of nearby existing and planned residential development,to minor increases in ambient noise levels.Noise typically College Park at Mountain House Specific Plan III Draft EIR EDAW San Joaquin County 4.13-17 Noise