18.40.090   SOUND ATTENUATION FOR RESIDENTIAL DEVELOPMENTS.
   .010   Applicability.  Residential developments involving the construction of two (2) or more dwelling units, or residential subdivisions resulting in two (2) or more parcels, and located within six hundred (600) feet of any railroad, freeway, expressway, major arterial, primary arterial or secondary arterial, as designated by the Circulation Element of the General Plan, shall comply with the provisions of this section.  The construction of an Accessory Dwelling Unit or Accessory Dwelling Unit – Junior shall not constitute a residential development subject to the provisions of this section.
   .020   Study Required.  A noise level analysis shall be performed for any new residential development or subdivision to determine the projected interior and exterior noise levels within the development. The study shall include mitigation measures that would be required to comply with applicable City noise standards, as identified in this section. The study shall be provided by the applicant, at its sole expense, to the City at the time of application for development of the residential development or subdivision.
   .030   Attenuation.  Mitigation measures, without limitation, may include masonry walls, an earthen berm or a combination thereof.  Masonry walls must comply with the requirements of Chapter 18.46 (Landscaping and Screening).  The height of any proposed walls shall be determined by the approval authority based on the recommendation of a sound attenuation study prepared by a state-licensed acoustical engineer, unless a variance is granted by the approval authority, or City Council on appeal, in accordance with the procedures established in Chapter 18.60 (Common Procedures) for the processing of variances.
   .040   Single-Family Detached.  Exterior noise within the private rear yard of any single family lot and/or within any common recreation areas, shall be attenuated to a maximum of sixty-five (65) dB CNEL.  Interior noise levels shall be attenuated to a maximum of forty-five (45) dB CNEL, or to a level designated by the Uniform Building Code, as adopted by the City.
   .050   Single-Family Attached or Multiple Family.  Exterior noise within common recreation areas of any single family attached or multiple family dwelling project shall be attenuated to a maximum of sixty-five (65) dB CNEL.  Interior noise levels shall be attenuated to a maximum of forty-five (45) dB CNEL, or to a level designated by the Uniform Building Code, as adopted by the City.
   .060   Minor Deviations.  Notwithstanding any provision of this Code to the contrary, the Planning Commission may grant a deviation from the requirements imposed by subsections .040 and .050 of this section pertaining to exterior noise levels in accordance with the procedures established in Chapter 18.60 (Common Procedures) for the processing of variances except that the findings set forth in Section 18.74.060 (Findings) of Chapter 18.74 (Variances) shall not be required and provided that before any such deviation is granted by the Planning Commission, the evidence presented shows that all of the following conditions exist:
      .0601   The deviation from prescribed levels does not pertain to interior noise levels;
      .0602   The deviation does not exceed five (5) dB CNEL above the prescribed levels for exterior noise; and
      .0603   Measures to attenuate noise to the prescribed levels would compromise or conflict with the aesthetic value of the project.  (Ord. 6000 § 3; November 8, 2005:  Ord. 6101 § 33; April 22, 2008:  Ord. 6317 § 14; March 3, 2015:  Ord. 6419 § 10; August 29, 2017:  Ord. 6483 § 9; June 9, 2020.)