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HomeMy WebLinkAboutNewport_Beach_Noise_Element_Review_6.27.2024 15443 1 JUNE 2024 MEMORANDUM To: Ben Zdeba, Principal Planner, City of Newport Beach From: Elizabeth Dickson, AICP, Senior Project Manager, Dudek Dana Lodico, PE, INCE Bd. Cert., Senior Acoustician, Dudek Subject: Review of City of Newport Beach General Plan Noise Element Date: June 27, 2024 Noise is one of eight topics required by California Government Code 65300 et al to be addressed in General Plans. Noise Elements aim to quantify current and projected noise levels from various sources to help inform land use compatibility and identify ways to reduce existing and potential noise impacts. One of the primary tools used to implement the Noise Element is the California Building Code which enforces maximum allowable interior noise levels for new multifamily residential development. Dudek is currently supporting the City of Newport Beach (City) in preparing a comprehensive update to the General Plan. As part of this effort, we have reviewed the City’s adopted Noise Element for relevance, completeness, and consistency with the Municipal Code. As a result of this review, we offer the following recommendations and suggestions. Background Section The information included in the Background Section is relevant. We agree that use of the Leq and CNEL metrics are appropriate for a Noise Element. However, language should be added to clarify that the sound levels described in the Background Section (after the definitions of the Leq and CNEL metrics) are meant to be exterior sound level exposures and not interior levels. This includes the statement that sound levels above 45 dBA at night can disrupt sleep. The World Health Organization recommends a sound level of 30 dBA or less inside bedrooms; assuming a standard exterior to interior sound reduction with modern construction and open windows of 15 dB, an exterior sound exposure of 45 dBA would equate to an interior exposure of 30 dBA. Also, we recommend clarifying that the noise levels stated, other than those in second sentence are Leq levels. See suggested text updates in the Summary of Recommendations Section. Context The Context Section is also relevant and thorough. We recommend that the City review the sections describing noise sources within the city to identify any new noise sources that may have been developed since the release of the adopted Noise Element. In addition, depending on the extent of new noise sources, the Community Noise Contour Maps may need to be updated with the current Existing and Forecasted traffic volumes and aircraft contours from John Wayne Airport (JWA). Goals and Policies The noise standards provided are consistent with the Municipal Code limits. We have the following observations and recommendations with regard to completeness and consistency. Text suggestions are provided in the Summary of Recommendations Section of this memorandum. MEMORANDUM SUBJECT: REVIEW OF NEWPORT BEACH NOISE ELEMENT 15443 2 JUNE 2024 ▪ Tables N2 and N3: Due to the differences in metrics being used between the two tables (CNEL in Table N2 and Leq in Table N3), we recommend adding a footnote to Table N3 that newly developed residential uses must also meet the interior Building Code requirement of 45 dBA CNEL / DNL. ▪ Table N3: For land uses that do not include nighttime use, such as schools, museums, and most commercial and industrial uses, nighttime noise limits are unnecessary. We recommend that these are removed or footnoted to only apply to land uses with nighttime use. ▪ Table N3, Footnote a: Note that if the standard is raised to meet the ambient, then the standards are essentially allowing a proposed project to increase the ambient sound level by as much as 3 dB. This is in agreement with the Table under N 1.8 for the 55 dBA CNEL sound level, but not for sound levels exceeding 55 dBA CNEL. We recommend that this footnote is updated to be consistent with this table. ▪ N 1.8: We recommend that language be updated for clarity. It is unclear whether the CNEL column refers to the existing of future ambient level. N 2.6: The City may want to include mention of other alternative methods, such as quieter pavement, use of solid safety barriers, and other methods. See https://www.trb.org/Publications/Blurbs/182634.aspx for a list of some strategies and associated costs and context that may be appropriate for the City. Summary of Recommendations The following is a summary of our recommendations to the City for updates to the Noise Element: • Background Section: The following is a suggestion of revised text for the last paragraph on page 12-3 (suggested changes are in blue): Noise environments and consequences of human activities are usually well represented by median noise levels during the day, night, or over a 24-hour period. Environmental noise levels are generally considered low when the exterior CNEL is below 55 dBA, moderate in the 55 to 70 dBA range, and high above 70 dBA. Examples of low daytime Leq exterior levels are isolated natural settings that can provide noise levels as low as 20 dBA, and quiet suburban residential streets that can provide noise levels around 40 dBA. Exterior noise levels above 45 dBA Leq at night can disrupt sleep. Examples of moderate exterior level noise environments are urban residential or semi-commercial areas (typically 55 to 60 dBA Leq) and commercial locations (typically 60 dBA Leq). People may consider louder environments adverse, but most will accept the higher levels associated with more noisy urban residential or residential-commercial areas (60 to 75 dBA Leq) or dense urban or industrial areas (65 to 80 dBA Leq). Additional examples of sound levels and loudness in indoor and outdoor environments are shown in Table N1. • Context Section: We recommend that the City review the sections describing noise sources within the city to identify any new noise sources that may have been developed since the release of the adopted Noise Element. In accordance with California Government Code 65302 (f), the Noise Element shall analyze and quantify, to the extent practicable, as determined by the legislative body, current and projected noise levels. To meet the intent of State law, the City should consider if there are new noise sources that may influence adopted contours. Given the extent of new noise sources, the Community Noise Contour Maps may need to be updated with the current Existing and Forecasted traffic volumes and aircraft contours from John Wayne Airport (JWA). Assessing changes to the adopted noise contour maps can be approached in a MEMORANDUM SUBJECT: REVIEW OF NEWPORT BEACH NOISE ELEMENT 15443 3 JUNE 2024 number of ways depending on the availability of data and as noted in State law, “to the extent practicable, as determined by the legislative body.” • Goals and Policy: We recommend the following changes be made: o The following updates to Table N3 are recommended: ▪ A footnote added stating that “In addition to the standards given in Table N3, newly developed residential uses must also meet the California Building Code Title 21 requirement of 45 dBA CNEL / DNL inside homes. This standard may be met with windows in the closed position if the residences is supplied with forced-air ventilation, so as to allow residents to keep windows shut.” ▪ For land uses in Table N3 that do not include nighttime use, such as schools, museums, and most commercial and industrial uses, nighttime noise limits may be removed or footnoted to only apply to land uses with nighttime use. ▪ Footnote a be updated to “If the ambient noise level exceeds the resulting standard, the ambient shall be the standard, so long as the resulting sound level increases do not exceed the standard in the Table under Policy 1.8.” o N 1.8 Significant Noise Increases (text) be updated as follows: ▪ Require the employment of noise mitigation measures for existing sensitive uses when a significant noise increase is identified. A significant noise increase occurs when there is an increase in the ambient CNEL due to sound produced by new development impacting existing sensitive uses. The CNEL increase that would be considered an impact is shown in the table below for exterior use areas or exterior façades of residences or other existing sensitive uses. ▪ The table heading should be updated to either “Existing Ambient CNEL (dBA)” or “Future CNEL (dBA)” depending on the City’s intentions. o In Policy N 2.6, The City may want to include mention of other alternative methods, such as quieter pavement, use of solid safety barriers, and other methods. See https://www.trb.org/Publications/Blurbs/182634.aspx for a list of some strategies and associated costs and context that may be appropriate for the City.