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HomeMy WebLinkAboutRS_Noise_Assessment_20201122_v1 (2).pdf Prepared for: Brent Planning Solutions On behalf of: Renton School District, King County, WA Prepared by: Ramboll US Corporation Lynnwood, Washington Date November 22, 2020 RENTON SCHOOL DISTRICT – ELEMENTARY SCHOOL NO. 16 NOISE ASSESSMENT Renton School District –Elementary School No. 16 Noise Assessment November 22, 2020 i Ramboll CONTENTS 1. Introduction ......................................................................................... 1 2. Noise Level Terminology and Human Hearing ...................................... 1 3. Affected Environment ........................................................................... 2 3.1 Applicable Noise Regulations ......................................................................... 2 3.2 Land Uses and Zoning .................................................................................. 3 3.3 Existing Sound Levels .................................................................................. 3 4. Operational Noise Impact .................................................................... 6 4.1 Noise Sources ............................................................................................. 6 4.1.1 On-Site Traffic .................................................................................. 6 4.1.2 Emergency Generator ........................................................................ 6 4.1.3 Chiller .............................................................................................. 7 4.2 Analysis Methods ........................................................................................ 7 4.3 Noise Assessment Results ............................................................................ 7 4.3.1 Compliance of On-Site Sources with Noise Limits .................................. 7 4.3.2 Increases Over Existing Noise Levels From All Project Sources ................ 8 5. Conclusions .......................................................................................... 9 TABLES Table 1: State Maximum Permissible Sound Levels (dBA) ............................................... 2 Table 2: Measured Existing Sound Levels (dBA) ............................................................ 4 Table 3: Calculated Sound Levels of On-site Sources (dBA) ............................................ 8 Table 4: Calculated Sound Level Increases during Morning Arrival (dBA) .......................... 9 FIGURES Figure 1. Sound Level Measurement and Receptor Locations ........................................... 5 APPENDICIES Appendix A: Sound Level Measurement Data Renton School District –Elementary School No. 16 Noise Assessment November 22, 2020 1 Ramboll 1. INTRODUCTION This report documents the noise impact assessment performed by Ramboll US Corporation (Ramboll) as part of the environmental review of Renton School District’s proposed Elementary School No. 16. The school is proposed to be located off Duvall Road, between NE 10th and NE 12th Streets in Renton, Washington. The nearest neighboring residential properties are adjacent to the northern and southern property boundaries. The analysis considered potential noise impacts at residences near the proposed project site from vehicles traveling on on-site roadways, an emergency generator, and an air-cooled chiller. The following report reviews noise terminology, regulatory and impact criteria applicable to the project, and the methods and findings of the analysis. 2. NOISE LEVEL TERMINOLOGY AND HUMAN HEARING The human ear responds to a very wide range of sound intensities. The decibel scale (dB) used to describe sound is a logarithmic rating system which accounts for the large differences in audible sound intensities. This scale accounts for the human perception of a doubling of loudness as an increase of 10 dB. Therefore, a 70-dB sound level will sound about twice as loud as a 60-dB sound level. People generally cannot detect differences of 1 dB; in ideal laboratory situations, differences of 2 or 3 dB can be detected by people, but such a change probably would not be detectable in an average outdoor environment. A 5-dB change would probably be perceived under normal listening conditions. When addressing the effects of noise on people, it is useful to consider the frequency response of the human ear. Sound-measuring instruments are therefore often programmed to weight measured sounds based on the way people hear. The frequency-weighting most often used is A-weighting because it approximates the frequency response of human hearing and is highly correlated to the effects of noise on people. Measurements from instruments using this system are reported in "A-weighted decibels" or dBA. All sound levels in this evaluation are reported in A-weighted decibels. Distance from the source, the frequency of the sound, the absorbency of the intervening ground, obstructions, and duration of the noise-producing event all affect the transmission and perception of noise. The degree of this effect also depends on who is listening and on existing sound levels. Renton School District –Elementary School No. 16 Noise Assessment Ramboll 2 November 18, 2020 3. AFFECTED ENVIRONMENT 3.1 Applicable Noise Regulations The proposed school property is located in the City of Renton and is subject to the noise regulations established by the Renton Municipal Code (RMC). Section 8-7-2 of the RMC identifies noise performance standards for commercial and industrial activities to be those identified in Chapter 173-60 of the Washington Administrative Code (WAC). Although the project is a public use, not commercial or industrial, no other quantitative limits are identified in RMC, and the levels identified in WAC 173-60 are applied here. WAC 173-60 establishes limits on sounds crossing property boundaries based on the Environmental Designation for Noise Abatement (EDNA) of the sound source and the receiving properties. The WAC EDNA classifications are based on the following land uses: • Class A – Lands where human beings reside and sleep (e.g., residences hospitals, camps, etc.) • Class B – Commercial areas and community services not used for human habitation (e.g., retail services, offices, schools, churches, etc.) • Class C – Industrial and agricultural areas The applicable noise limits for each EDNA Class source and receiver combination are listed in Table 1. Table 1. State Maximum Permissible Sound Levels (dBA) EDNA of Sound Source EDNA of Receiving Property Class A Day/Night Class B Class C Class A 55 / 45 57 60 Class B 57 / 47 60 65 Class C 60 / 50 65 70 The limitations for noise received in Class A EDNAs are reduced by 10 dBA during nighttime hours, defined as between 10 PM and 7 AM. Source: WAC 173-60-40 The "maximum permissible" environmental noise levels in Table 1 may be exceeded for short periods by a total of not more than 15 minutes in any one-hour period. The allowed short-term increases are as follows: 5 dBA for no more than 15 minutes in any hour, or 10 dBA for no more than 5 minutes of any hour, or 15 dBA for no more than 1.5 minutes of any hour. Renton School District –Elementary School No. 16 Noise Assessment November 22, 2020 3 Ramboll 3.2 Land Uses and Zoning The proposed school site and the surrounding properties are zoned Residential (R8) and Residential Multi-Family (RMF). The use of the site for a school would classify the school as a Class B noise source according to WAC 173-60-030. The adjacent residential properties are classified as Class A receivers. The noise limits for a Class B noise source affecting a Class A receiver are 57 dBA during daytime hours (7 AM to 10 PM) and 47 dBA at night (10 PM to 7 AM). Allowable short-term increases to the above levels are as described previously. 3.3 Existing Sound Levels On October 6 to 7, 2020, Ramboll measured day-long sound levels in the vicinity of the new school. Measurements were taken at three locations to determine the existing noise levels near adjacent residential property boundaries. Measurements were taken near the northwestern (SLM1), eastern (SLM2), and southeastern boundaries (SLM3) using Larson Davis Type I sound level meters (Model LxT). The meters had been factory certified within the previous 12 months and were field calibrated immediately prior to the measurement. The microphones of the meters were fitted with wind screens and set approximately 5 feet above the ground (at a typical listening height). The measured sound levels are summarized in Table 2, and the sound level measurement locations are depicted in Figure 1. Details of hourly sound level measurements are found in Appendix A. Renton School District –Elementary School No. 16 Noise Assessment Ramboll 4 November 18, 2020 Table 2. Measured Existing Sound Levels (dBA) Location Time of Day (a) Range of Sound Levels (dBA) (b) Leq Lmax L2.5 L8.3 L25 L90 SLM1 Day 50 - 60 62 - 80 54 - 60 51 - 57 50 - 55 45 - 50 Night 48 - 55 54 - 68 45 - 53 42 - 50 40 - 48 38 - 44 School Day 53 - 60 62 - 80 54 - 59 53 - 56 51 - 54 45 - 50 SLM2 Day 60 - 67 76 - 96 68 - 71 65 - 70 61 - 68 45 - 56 Night 50 - 63 70 - 81 60 - 69 50 - 67 39 - 65 33 - 48 School Day 64 - 67 76 - 95 70 - 71 68 - 69 65 - 67 49 - 54 SLM3 Day 47 - 62 61 - 100 52 - 69 50 - 62 48 - 56 39 - 47 Night 36 - 46 54 - 67 43 - 51 38 - 49 35 - 47 33 - 40 School Day 47 - 56 61 - 80 52 - 62 50 - 60 48 - 52 40 - 45 (a) "Day" refers to the hours between 7 AM and 10 PM. "Night" refers to the hours between 10 PM and 7 AM. “School Day” refers to the potential operating hours of the school, expected to fall between 8 AM and 4 PM. (b) The Leq is the "energy-averaged" sound level. The Lmax is the-highest measured sound level. The L90 is the sound level exceeded 90% of the time and is often considered representative of the background sound level. The L2.5, L8.3, and L25 County noise limit levels that are defined previously in this report in the discussion of the regulatory noise limits. These measurements were taken from October 6 to 7, 2020. Renton School District –Elementary School No. 16 Noise Assessment November 22, 2020 5 Ramboll Figure 1. Sound Level Measurement and Receptor Locations Renton School District –Elementary School No. 16 Noise Assessment Ramboll 6 November 18, 2020 4. OPERATIONAL NOISE IMPACT 4.1 Noise Sources Potential sources of noise associated with Elementary School No. 16 include buses and vehicles traveling on on-site roadways, operation of an emergency generator during power outages and monthly generator maintenance, and an air-cooled chiller. These noise sources are described more completely below. 4.1.1 On-Site Traffic On-site traffic would include school buses and parents and staff vehicles entering, traversing, and departing on the site. Traffic volumes were provided by Heffron Transpiration Inc. for the higher of the estimated AM and PM peak values of morning arrival/drop-off and afternoon departure/pickup. Because traffic volumes during the morning arrival hour are estimated to be greater than during afternoon departure, the focus of the noise assessment is on the morning arrival hour. For purposes of this assessment, peak morning arrival hour is assumed to occur between 8 and 9 AM, and the on-site traffic speed is assumed to be 10 mph. In the bus loop east of the school building, 8 school buses would enter the northern driveway, drop off children, and depart south from the site during the peak morning arrival hour. In the parking area and parent drop-off loop south of the school building, 234 vehicles would enter the site via the eastern driveway during peak morning arrival and exit from the west driveway onto Chelan Ave NE. In addition, 53 vehicles would enter the eastern driveway and remain on site and park in the southern lot. 4.1.2 Emergency Generator An emergency generator is proposed to be located in a service yard on the west side of the building. The service yard is assumed to be enclosed by an 8-foot high wall, except for an access/opening. The emergency generator would not generally operate except in emergencies during power outages, and emergency operation of the generators is exempt from the noise limits. However, maintenance of the generator requires it be operated occasionally, typically for one hour or so once a month. Maintenance would occur during daytime hours only. At the time of this report, the exact make and model of the emergency generator was unknown, but it is expected to have a capacity of 100 kilowatts and use natural gas. The estimated sound level of the generator used in this analysis is 70 dBA at 23 feet. Renton School District –Elementary School No. 16 Noise Assessment November 22, 2020 7 Ramboll 4.1.3 Chiller A Daikin air-cooled screw chiller (chiller) is proposed to be located in the service yard on the east side of the building, near the generator. The chiller could operate anytime during the day and also potentially during early morning hour between 6 and 7 AM, and noise from the unit would be required to comply with both the daytime and stricter nighttime noise limits at the nearest residences to the school. The chiller was conservatively assumed to be running at 100% load, with a sound level of 70 dBA at 30 feet. Noise from chiller operations was included in the assessment of early morning hours before 7 AM, during peak morning arrival, and during daytime maintenance of the generator. 4.2 Analysis Methods Ramboll assessed sound levels associated with expected on-site sources of noise for the following three operating scenarios: • Chiller Operation Only – operation of the chiller between 6 and 7 AM • Peak Morning Arrival – operation of the chiller and on-site traffic between 8 and 9 AM • Generator Maintenance – operation of the chiller and maintenance/operation of the emergency generator during daytime hours Noise modeling of on-site sources was completed using the CadnaA noise model. CadnaA is a computer tool that calculates sound levels after considering the noise reductions or enhancements caused by distance, topography, varying ground surfaces, atmospheric absorption, and meteorological conditions. For point sources of noise, such as emergency generators, the model uses algorithms that comply with the international standards in ISO-9613-2:1996. For traffic noise emissions, the CadnaA model used for this analysis is equipped with the US Federal Highway Administration (FHWA) Traffic Noise Model (TNM) standard. The modeling process includes the following steps: (1) characterizing the noise sources, (2) creating 3-dimensional maps of the site and vicinity to enable the model to evaluate effects of distance and topography on noise attenuation, and (3) assigning equipment and activity sound levels to appropriate locations on the site. CadnaA then constructs topographic cross sections to calculate sound levels in the vicinity of a project site. 4.3 Noise Assessment Results 4.3.1 Compliance of On-Site Sources with Noise Limits Model-calculated results of the early morning chiller operation, morning arrival, and daytime generator maintenance operations are presented in Table 3. As shown in Table 3, expected activities on the site do not exceed the applicable daytime or nighttime noise limits. Renton School District –Elementary School No. 16 Noise Assessment Ramboll 8 November 18, 2020 Table 3. Calculated Sound Levels of On-site Sources (dBA) Receptor Chiller Only (a) Morning Arrival (b) Generator Maintenance (c) Noise Limit(d) R1 38 40 40 57 / 47 R2 40 46 43 57 / 47 R3 41 45 40 57 / 47 R4 44 48 47 57 / 47 R5 43 48 45 57 / 47 R6 39 46 41 57 / 47 R7 30 48 32 57 / 47 R8 27 48 29 57 / 47 R9 25 48 27 57 / 47 R10 25 48 24 57 / 47 R11 23 28 23 57 / 47 Notes: (a) Early morning operation of the chiller (i.e., prior to 7 AM) would be subject to the stricter nighttime noise limit. (b) Morning arrival includes traffic traveling on-site between 8 and 9 AM and operation of the chiller. (c) Generator maintenance includes operation of the generator and chiller during daytime hours. (d) The noise limits are presented as daytime/nighttime limits. Daytime hours are between 7 AM and 10 PM. Nighttime hours are between 10 PM and 7 AM. Source: Ramboll, 2020 4.3.2 Increases Over Existing Noise Levels From All Project Sources In addition to considering compliance with the applicable noise limits, Ramboll considered the potential for noise impacts due to project-related increases in sound levels compared to background levels. The assessment was conducted for peak morning arrival only, since this was the worst-case scenario considered. Project-related increases during both early morning chiller operation and midday generator maintenance are expected to be lower. Furthermore, potential increases during generator maintenance would be infrequent and short-term. Table 4 displays the calculated sound level increases expected during morning arrival. As shown, the highest calculated increase of 2 dBA could be expected at residences near the south parking lot. No increases are expected near residences primarily affected by traffic along Duvall Avenue Northeast. Increases of 0 to 2 dBA would not typically be discernable in an active, outdoor environment. Renton School District –Elementary School No. 16 Noise Assessment November 22, 2020 9 Ramboll Table 4. Calculated Sound Level Increases during Morning Arrival (dBA) Receptor Measured Existing Level(a) Modeled Morning Arrival (b) Cumulative Level(c) Increase Over Existing R1 52 40 53 0 R2 52 46 53 1 R3 67 45 67 0 R4 67 48 67 0 R5 67 48 67 0 R6 67 46 67 0 R7 67 48 67 0 R8 50 48 52 2 R9 50 48 52 2 R10 50 48 52 2 R11 50 28 50 0 Notes: The above values are rounded to the whole number, and apparent calculation errors are due to the rounding. (a) Existing sound levels are based on the hourly level between 8 and 9 AM (i.e., representing the AM peak traffic hour) (b) Model-calculated sound levels of all on-site traffic and chiller operation. (c) Overall levels include the existing measured levels plus all project-related noise. Source: Ramboll, 2020 5. CONCLUSIONS The proposed new Elementary School No. 16 would introduce traffic, an emergency generator, and cooling equipment to the project site. Model-calculated sound levels of chiller operation indicate compliance with both the daytime and nighttime noise limits. Model- calculated sound levels of on-site traffic and chiller operations during peak morning arrival indicate compliance with the applicable noise limits during daytime hours. Similarly, model- calculated sound levels of chiller operations simultaneously with generator maintenance indicates this activity would comply with the daytime noise limits at all receptor locations. Consideration of potential increases in noise due to morning arrival traffic and chiller operation results in estimated increases of 0 to 2 dBA at all residences near the site. Such increases in an active, outdoor environment would be difficult to discern, and the project is not expected to result in substantial noise impacts. Renton School District –Elementary School No. 16 Noise Assessment A-1 Ramboll APPENDIX A: SOUND LEVEL MEASUREMENT DATA Ramboll A-2 SLM1 - Near Northern Property Boundary Date/Time Leq Lmax L2.5 L8.3 L25 L90 10/6/20 14:00 53.2 76.2 57.1 55.2 53.4 49.7 10/6/20 15:00 53.5 74.5 57.0 55.8 54.1 49.5 10/6/20 16:00 53.3 67.6 57.4 55.8 54.2 49.6 10/6/20 17:00 56.1 79.8 60.3 56.6 54.8 50.0 10/6/20 18:00 52.9 71.7 56.7 55.2 53.4 48.8 10/6/20 19:00 52.4 77.3 56.8 54.6 52.4 47.7 10/6/20 20:00 49.9 63.3 54.5 52.5 50.6 45.9 10/6/20 21:00 49.5 73.8 54.5 52.3 49.7 45.4 10/6/20 22:00 46.0 64.7 51.3 48.4 46.2 42.9 10/6/20 23:00 44.5 59.2 50.1 47.2 44.6 41.0 10/7/20 0:00 42.4 59.6 47.8 44.9 42.3 39.3 10/7/20 1:00 41.7 59.5 46.4 44.2 41.9 38.6 10/7/20 2:00 40.3 56.2 44.7 42.3 39.9 38.4 10/7/20 3:00 42.3 60.7 48.9 44.5 41.0 38.2 10/7/20 4:00 41.8 54.0 46.3 44.2 42.2 39.0 10/7/20 5:00 46.2 65.8 51.5 48.7 46.5 41.4 10/7/20 6:00 48.3 67.8 53.4 50.2 48.1 44.1 10/7/20 7:00 49.0 65.7 53.7 51.3 49.5 45.5 10/7/20 8:00 52.4 75.9 55.8 53.6 51.5 46.0 10/7/20 9:00 52.5 79.6 55.7 53.9 51.9 45.8 10/7/20 10:00 49.8 61.8 54.2 52.6 50.8 45.3 10/7/20 11:00 52.8 74.1 58.6 56.4 53.2 46.7 10/7/20 12:00 53.7 78.6 57.4 56.0 53.3 47.5 10/7/20 13:00 51.3 68.0 56.1 54.1 51.9 46.7 Renton School District –Elementary School No. 16 Noise Assessment A-3 Ramboll SLM2 - Near Eastern Property Boundary Date/Time Leq Lmax L2.5 L8.3 L25 L90 10/6/20 14:00 64.1 81.3 69.9 68.2 65.5 53.1 10/6/20 15:00 65.2 77.9 70.7 69.1 66.8 53.3 10/6/20 16:00 65.8 78.9 71.1 69.7 67.4 55.0 10/6/20 17:00 66.0 77.4 71.3 69.9 67.7 56.0 10/6/20 18:00 65.4 86.7 71.1 69.5 66.8 54.8 10/6/20 19:00 65.3 95.7 69.9 67.8 65.0 50.9 10/6/20 20:00 62.1 82.5 69.0 66.9 63.3 47.0 10/6/20 21:00 60.2 77.1 67.7 65.2 61.0 45.0 10/6/20 22:00 58.1 76.9 66.7 63.6 57.2 41.0 10/6/20 23:00 56.2 76.2 65.9 61.5 51.6 37.7 10/7/20 0:00 53.7 74.6 63.8 57.2 46.1 34.1 10/7/20 1:00 50.9 72.0 61.6 50.4 39.5 32.7 10/7/20 2:00 49.8 73.6 60.2 49.5 39.4 32.6 10/7/20 3:00 52.1 70.0 63.1 55.0 42.7 33.5 10/7/20 4:00 53.9 72.9 63.9 59.4 47.9 36.5 10/7/20 5:00 59.3 74.9 67.5 64.8 59.7 41.7 10/7/20 6:00 63.1 81.1 69.1 67.4 64.8 48.4 10/7/20 7:00 64.6 79.2 70.3 68.5 66.1 52.8 10/7/20 8:00 66.6 95.1 70.8 69.1 66.7 51.3 10/7/20 9:00 64.1 75.8 70.0 68.4 65.9 48.9 10/7/20 10:00 63.6 77.6 69.8 67.7 65.0 49.1 10/7/20 11:00 64.0 77.0 69.7 68.0 65.5 51.5 10/7/20 12:00 64.6 76.9 70.1 68.3 66.0 53.9 10/7/20 13:00 64.3 82.3 70.1 68.1 65.6 51.7 Ramboll A-4 SLM3 - Near Southern Property Boundary Date/Time Leq Lmax L2.5 L8.3 L25 L90 10/6/20 14:00 55.8 80.5 61.6 60.4 52.3 45.4 10/6/20 15:00 49.8 60.8 54.4 52.8 50.9 44.8 10/6/20 16:00 53.0 74.8 60.6 54.0 51.6 45.5 10/6/20 17:00 62.4 100.5 68.5 62.4 55.8 47.1 10/6/20 18:00 50.2 72.9 54.8 52.9 50.8 44.9 10/6/20 19:00 50.3 74.0 55.4 53.0 50.4 43.5 10/6/20 20:00 46.8 64.5 52.4 50.4 47.7 39.6 10/6/20 21:00 46.8 61.7 53.3 50.6 47.5 39.2 10/6/20 22:00 43.8 59.3 50.3 48.0 44.4 37.0 10/6/20 23:00 41.5 58.4 49.0 45.6 40.9 34.8 10/7/20 0:00 39.2 60.5 46.3 42.8 37.2 33.4 10/7/20 1:00 36.3 58.9 43.7 38.9 35.0 32.6 10/7/20 2:00 36.0 58.1 43.0 38.4 34.7 32.7 10/7/20 3:00 40.3 60.2 47.5 41.8 36.3 33.2 10/7/20 4:00 39.3 53.6 45.4 43.1 39.2 34.7 10/7/20 5:00 44.0 64.0 50.1 47.3 44.5 38.2 10/7/20 6:00 46.2 66.7 51.0 49.3 47.2 39.8 10/7/20 7:00 48.1 73.6 53.1 50.7 48.5 41.5 10/7/20 8:00 49.9 78.7 53.3 51.1 48.9 41.3 10/7/20 9:00 46.9 70.7 51.8 50.2 48.1 39.5 10/7/20 10:00 46.7 63.0 51.8 49.9 47.8 40.4 10/7/20 11:00 47.1 65.9 52.4 50.1 47.8 41.5 10/7/20 12:00 47.8 72.0 52.6 50.4 48.2 42.1 10/7/20 13:00 48.4 68.3 53.8 50.9 48.2 41.5