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III. ENVIRONMENTAL SETTING,IMPACTS AND MITIGATION MEASURES D. NOISE noise environmentP rovided the resultant noise level is within the limits of its noise/land use compatibility guidelines. The City considers a noise environment of up to 60 DNL to be acceptable for residential uses. A noise environment of up to 65 DNL is allowable provided the best practicable and available noise reduction features have been incorporated in the project design(i.e., a noise barrier). For residential areas where the resultant noise level would exceed 65 DNL,the City considers a 1.5-DNL increase in noise to be significant. In addition to the relative criteria described above, the City has exterior noise level standards for stationary sources located in close proximity to residential areas. Table III.D-1 summarizes these standards in terms of the hourly and maximum daytime and nighttime noise levels not to be exceeded by project operations at nearby residential properties. This analysis focuses on the potential for the project to exceed the City's hourly Leq standards. Temporary impacts during construction are considered significant if they would be substantially greater than existing ambient noise levels, would substantially interfere with affected land uses, would continue for a substantial period, or would affect noise-sensitive uses during the nighttime. METHODOLOGY Noise impacts of the project could include temporary construction noise,operational noise from increased transfer station activities at the site, and increased vehicle noise along local roadways providing access to and from the project site. Construction noise impacts were assessed based upon an assumed mixture of construction equipment and related noise levels. Noise levels of individual types of equipment are based on industry averages. Assumptions related to construction equipment mixture and industry noise averages were used to evaluate construction-related noise impacts. Operational noise impacts would primarily be related to on-site activities. In addition,noise associated with increased vehicle trips along selected haul routes would be expected to increase marginally. Traffic data presented in Section III.0(Traffic Circulation and Safety) were used for transportation noise impact modeling. To assess transportation related noise impacts, the Federal Highway Administration's (FHWA)Noise Prediction Model,after being adjusted to utilize California vehicle noise emission factors, was used to estimate roadside noise levels along the most impacted roadways. Traffic noise impacts were evaluated along roadway segments where sensitive receptors are located and where project-related peak-hour traffic volumes would double (or approach doubling) existing peak-hour traffic volumes, as shown in Section III.C,Traffic Circulation and Safety. Operational noise impacts with respect to the expanded transfer station activities were evaluated based on field survey and noise monitoring conducted at other similar facilities. Stockton Scavenger Transft r Station bpansion III.D.10 ESA 1990190