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5.0 Environmental Analysis 5.6 Noise Avion Project SEIR Page 5.6-1 5.6 Noise This section evaluates potential noise impacts associated with the project. The following discussion is based upon the Noise Analysis (RECON 2019e) prepared by RECON and included as Appendix E. 5.6.1 Relationship to the Black Mountain Ranch (Subarea I) Subarea Plan The analysis in this section updates the noise analysis in the 1998 Environmental Impact Report (EIR), with an emphasis on effects that were not addressed in the previous report. Because no site- specific design was proposed at the time the 1998 EIR was prepared, impacts relative to construction noise, including blasting impacts, could not be analyzed in detail for the perimeter properties, including the project site. Construction-related noise impacts, including impacts to the adjacent Multi-Habitat Planning Area (MHPA) from development of the Southeast Perimeter properties, were considered to be potentially significant. The Noise Analysis addresses anticipated construction noise associated with land preparation activities, including blasting, which was not considered in the 1998 EIR analysis. Operational noise impacts were adequately analyzed as part of the 1998 EIR, to which this Supplemental Environmental Impact Report (SEIR) is tiered. Those impacts are summarized in Chapter 9.0. 5.6.2 Existing Conditions The project site is located in a developing area that consists primarily of residential development and open space. A majority of the project site is surrounded by open space. The nearest circulation element roadway is Carmel Valley Road, which is approximately 2,800 feet to the north. Local residential streets are located in the newly constructed single-family residential neighborhood to the northeast. However, these local streets only provide access to the neighborhood and do not carry a significant amount of traffic. Existing noise levels on the project site would be similar to an open space and single-family residential neighborhood, which are relatively quiet. Distant vehicle traffic on Carmel Valley Road is the main transportation-related noise source. The existing traffic volume and speed for Carmel Valley Road were obtained from the San Diego Association of Governments Traffic Forecast Information Center (SANDAG 2019). Based on an existing traffic volume of 26,800 and a speed of 50 miles per hour on Carmel Valley Road, using Federal Highway Administration (FHWA) algorithms, it was calculated that the existing vehicle traffic noise level on the project site is approximately 57 CNEL (Appendix E). 5.6.2.1 Fundamentals of Noise Sound levels are described in units called the decibel (dB). Decibels are measured on a logarithmic scale that quantifies sound intensity in a manner similar to the Richter scale used for earthquake magnitudes. Thus, a doubling of the energy of a noise source, such as doubling of traffic volume, would increase the noise level by 3 dB; a halving of the energy would result in a 3 dB decrease. However, human perception of noise has no simple correlation with acoustical energy. A change in