Appendix G: Noise Supporting Information

Transcription

1 City of Livermore Sunset Crossing Project/Catalina Crossing Project Draft EIR Appendix G: Noise Supporting Information FirstCarbon Solutions H:\Client (PN-JN)\1728\ \3 - Draft EIR\edit-wp\ Sec99-00 Appendix Dividers.doc

2 City of Livermore Sunset Crossing Project/Catalina Crossing Project Draft EIR G.1 - Sunset Office Plaza Sunset Crossing FirstCarbon Solutions H:\Client (PN-JN)\1728\ \3 - Draft EIR\edit-wp\ Sec99-00 Appendix Dividers.doc

3 13 June 2013 Chris Truebridge One Annabel Lane, Suite 201 San Ramon, CA Phone: (925) Subject: Sunset Office Plaza Sunset Crossing CSA Project: Dear Chris: As requested, we have conducted an environmental noise study for this project. The purpose of the study is to determine the noise environment at the proposed site, compare the noise environment with applicable standards, and propose mitigation measures as necessary. This report summarizes the results of our study. EXECUTIVE SUMMARY 1. To meet the State and City indoor noise standard, some windows and exterior doors will need STC ratings up to STC To meet the City s exterior noise goal, sound walls will be needed along Concannon Boulevard and Holmes Street. DESCRIPTION The project is located on the northeast corner of Concannon Boulevard and Holmes Street. Traffic along these two streets dominates the noise environment at the site. Residential single-family homes border the site to the north and east, and adjacent homes have sound walls of varying heights. The topography is such that the site is on grade with Holmes Street and approximately 5-feet lower than Concannon Boulevard. The 11 June 2013 site plan indicates that 38 townhomes and 49 single-family residences will be built on the site. The residences are one- and two-story. The exterior space consists of one central outdoor area in addition to backyards of single-family residences.

4 Sunset Office Plaza 13 June 2013 Page 2 PROJECT CRITERIA State Noise Standards Title 24, Chapter 12 of the California Building Code (CBC) requires that the indoor noise level in new multi-family housing not exceed DNL 1 45 db where the exterior noise level is greater than DNL 60 db. The CBC also states that if windows must be closed to meet the interior standard, the design must include a ventilation or air-conditioning system to provide a habitable interior environment. The CBC does not include interior noise standards for single-family residences. City Noise Guidelines The City of Livermore Noise Element of the General Plan is consistent with the State Standards in regards to interior noise levels for multi-family housing (Objective N-1.3, Action A1). Residential developments in the Downtown Area cannot exceed interior noise levels of up to 45 dba with windows closed (Objective N1.1, Policy 6). Similarly, habitable buildings located within 100-feet from the centerline of railroad tracks must also meet the 45 dba interior noise criteria (Objective N-1.2, Action A3). Though the site is neither downtown nor within 100-feet of railroad tracks, we understand that the single-family residences in this project are being held to this standard. The City requires that exterior noise in backyards not exceed CNEL 2 65 dba for multi-family development or CNEL 60 dba for single-family development (Objective N-1.4, Policy P4). Furthermore, Table 9-7 (below) in the Noise Element indicates that an exterior CNEL or DNL of 65 dba or less is normally acceptable in residential multi-family areas and that an exterior CNEL or DNL of 60 dba or less is normally acceptable in residential single-family areas. Table 9.7: Land Use Compatibility Guidelines for Exterior Noise (CNEL or DNL) Land Use Category Normally Conditionally Normally Clearly Acceptable Acceptable Unacceptable Unacceptable Residential Single-Family 60 dba dba dba > 75 dba Residential Multi-Family 65 dba dba dba > 75 dba 1 2 Day-Night Average Sound Level (DNL) A descriptor established by the U.S. Environmental Protection Agency to describe the average day-night level with a penalty applied to noise occurring during the nighttime hours (10 pm to 7 am) to account for the increased sensitivity of people during sleeping hours. Community Noise Equivalent Level (CNEL) A descriptor for the 24-hour A-weighted average noise level. The CNEL concept accounts for the increased acoustical sensitivity of people to noise during the evening and nighttime hours. Sound levels during the hours from 7 pm to 10 pm are penalized 5 db; sound levels during the hours from 10 pm to 7 am are penalized 10 db. A 10-dB increase in sound level is perceived by people to be a doubling of loudness. There is less than 1 db difference between DNL and CNEL.

5 Sunset Office Plaza 13 June 2013 Page 3 ANALYSIS AND RECOMMENDATIONS To quantify the existing noise environment, we conducted two 72-hour noise measurements near the property lines of the project site between 16 and 19 May The meters were attached to poles along Concannon Boulevard and Holmes Street at a height of approximately 12 feet. Table 1 (below) and Figure 1 (enclosed) show the measurement locations and measured DNL around the project site. A future traffic analysis was provided for this project, so we have added 1 db to the measured noise levels to account for future traffic increases. We used the 21 May 2013 plans and elevations with the 11 June 2013 site plan as the basis of our analysis. Table 1: Summary of Noise Measurement Results Monitor Location Noise Level (DNL) L1 L2 45 south from Concannon Boulevard 740 east from Holmes Street 12 above grade 40 west from Holmes Street 950 north from Concannon Boulevard 12 above grade 70 db 74 db Interior Noise To meet the interior Code requirement of DNL 45 db, it will be necessary for exterior window and door assemblies to be sound-rated with STC 3 ratings up to STC 38. We have assumed carpeting in the bedrooms and hard-surfaced floors in all other rooms for our calculations. Minimum required STC ratings are shown on Figures 2 and 3 (enclosed). For our calculations, we have also assumed that the recommended sound walls (see Figure 4 and below) will be incorporated. Some of the single-family residences would need increased STC ratings if the recommended sound walls are not incorporated into the design. Typical construction-grade dual-pane windows achieve an STC rating of 28. One-inch assemblies (two 1/4-inch thick panes with a 1/2-inch airspace) typically achieve an STC rating of approximately 32. It is important to note that the recommended STC ratings are for full window assemblies (glass-andframe) rather than just the glass itself. Tested sound-rated assemblies should be used. If non-tested assemblies were to be used, the STC rating of the glass would likely need to be increased. The California Building Code (CBC) requires that where windows need to be closed to achieve an indoor DNL of 45 db, an alternative method of supplying fresh air (e.g., mechanical ventilation) must 3 Sound Transmission Class (STC) A single-figure rating standardized by ASTM and used to rate the sound insulation properties of building partitions. The STC rating is derived from laboratory measurements of a particular building element and as such is representative of the maximum sound insulation. Increasing STC ratings correspond to improved noise isolation.

6 Sunset Office Plaza 13 June 2013 Page 4 be provided. This applies to all of the multi-family residences with sound-rated window assemblies. We recommend applying this to all of the single-family residences with sound-rated windows also. This issue should be discussed with the project mechanical engineer. Exterior Noise To meet the City s exterior noise goal of DNL 65 db for the central open area associated with the multifamily portions of the site, no mitigation is needed. The new residences are expected to provide enough shielding to this open area to reduce the noise level to DNL 65 db or below. To meet the City s exterior noise goal of DNL 60 db for homes along Concannon Boulevard, a 10-foot tall sound barrier (measured from the finished pad elevation) is needed along Concannon Boulevard, as shown in Figure 4. The existing topography already provides approximately 5-feet of the sound barrier, so an additional barrier approximately 5-feet tall is needed along the crest of the terrain. The portions of the sound wall that are perpendicular to Concannon Boulevard can step down to 7 feet. A 5-foot tall sound barrier is also needed along the southern property line of Lot 7. To meet the City s exterior noise goal of DNL 60 db for the home along Holmes Street (Lot 25), an 11- foot tall sound barrier is needed along Holmes Street, as shown in Figure 4. Alternatively, a 7-foot tall sound barrier is calculated to reduce the noise level to DNL 65 db, if the noise goal can be relaxed. Both of these mitigation measures assume that a 6-foot tall fence spans between Lots 24 and 25. The sound barriers must be continuous from grade to top with no cracks or gaps in the face and have a minimum surface density of three pounds per square foot. Earth berms or wooden fences with this density would be appropriate. These exterior noise mitigation measures are consistent with neighboring residential developments along Concannon Boulevard and Holmes Street. * * * This concludes our environmental noise study for the Sunset Office Plaza. Should you have any questions, please give us a call. Sincerely, CHARLES M. SALTER ASSOCIATES Shanna M. Sullivan Consultant Jeremy L. Decker Principal Consultant

7 L2: DNL 74 db L1: DNL 70 db

8 = STC 28 = STC 29 = STC 30 = STC 32 = STC 34 = STC 36 = STC 38

9 = STC 28 = STC 29 = STC 30 = STC 32 = STC 34 = STC 36 = STC 38

10 ASSUMING 6' FENCE SOUND WALL (11'- 0" HIGH) SOUND WALL (5'- 0" HIGH) SOUND WALL (7'- 0" HIGH) SOUND WALL (10'- 0" HIGH)

11 City of Livermore Sunset Crossing Project/Catalina Crossing Project Draft EIR G.2 - Livermore Financial Center Catalina Crossing FirstCarbon Solutions H:\Client (PN-JN)\1728\ \3 - Draft EIR\edit-wp\ Sec99-00 Appendix Dividers.doc

12 11 June 2013 Chris Truebridge One Annabel Lane, Suite 201 San Ramon, CA Phone: (925) Subject: Livermore Financial Center Catalina Crossing CSA Project: Dear Chris: As requested, we have conducted an environmental noise study for this project. The purpose of the study is to determine the noise environment at the proposed site, compare the noise environment with applicable standards, and propose mitigation measures as necessary. This report summarizes the results of our study. EXECUTIVE SUMMARY 1. To meet the State and City indoor noise standard, some windows and exterior doors will need STC ratings up to STC No mitigation is necessary to meet the City s exterior noise goal. DESCRIPTION The project is located south of Catalina Drive, between Catalina Court and Barcelona Street. Traffic along Concannon Boulevard (approximately 350-feet south of the site) and Catalina Court dominate the noise environment at the site. Residential multi-family homes border the site to the north and west, and commercial buildings are south and east of the site. The 7 March 2013 site plan indicates that 31, two-story townhomes will be built on the site. The exterior space consists of one central outdoor area along Catalina Court. PROJECT CRITERIA State Noise Standards Title 24, Chapter 12 of the California Building Code (CBC) requires that the indoor noise level in new multi-family housing not exceed DNL 1 45 db where the exterior noise level is greater than DNL 60 db. 1 Day-Night Average Sound Level (DNL) A descriptor established by the U.S. Environmental Protection Agency to describe the average day-night level with a penalty applied to noise occurring during the nighttime hours (10 pm to 7 am) to account for the increased sensitivity of people during sleeping hours.

13 Sunset Office Plaza 11 June 2013 Page 2 The CBC also states that if windows must be closed to meet the interior standard, the design must include a ventilation or air-conditioning system to provide a habitable interior environment. City Noise Guidelines The City of Livermore Noise Element of the General Plan is consistent with the State Standards in regards to interior noise levels for multi-family housing (Objective N-1.3, Action A1). The City requires that exterior noise in backyards not exceed CNEL 2 65 dba for multi-family development (Objective N-1.4, Policy P4). Furthermore, Table 9-7 (below) in the Noise Element indicates that an exterior CNEL or DNL of 65 dba or less is normally acceptable in residential multifamily areas. Table 9.7: Land Use Compatibility Guidelines for Exterior Noise (CNEL or DNL) Normally Conditionally Normally Clearly Land Use Category Acceptable Acceptable Unacceptable Unacceptable Residential Multi-Family 65 dba dba dba > 75 dba ANALYSIS AND RECOMMENDATIONS To quantify the existing noise environment, we conducted two 72-hour noise measurements near the property lines of the project site between 16 and 19 May The meters were attached to poles along Catalina Drive and Barcelona Street at a height of approximately 12 feet. Table 1 (below) and Figure 1 (enclosed) show the measurement locations and measured DNL around the project site. A future traffic analysis was provided for this project, so we have added 1 db to the measured noise levels to account for future traffic increases. We used the 21 May 2013 plans and elevations with the 7 March 2013 site plan as the basis of our analysis. Table 1: Summary of Noise Measurement Results Monitor Location Noise Level (DNL) L1 L2 30 north from Catalina Drive 830 west from Holmes Street 12 above grade 20 east from Barcelona Street 370 north from Concannon Boulevard 12 above grade 63 db 65 db 2 Community Noise Equivalent Level (CNEL) A descriptor for the 24-hour A-weighted average noise level. The CNEL concept accounts for the increased acoustical sensitivity of people to noise during the evening and nighttime hours. Sound levels during the hours from 7 pm to 10 pm are penalized 5 db; sound levels during the hours from 10 pm to 7 am are penalized 10 db. A 10-dB increase in sound level is perceived by people to be a doubling of loudness. There is less than 1 db difference between DNL and CNEL.

14 Sunset Office Plaza 11 June 2013 Page 3 Interior Noise To meet the interior Code requirement of DNL 45 db, it will be necessary for exterior window and door assemblies to be sound-rated with STC 3 ratings up to STC 28. We have assumed carpeting in the bedrooms and hard-surfaced floors in all other rooms for our calculations. Minimum required STC ratings are shown on Figure 2 (enclosed). Typical construction-grade dual-pane windows achieve an STC rating of 28. One-inch assemblies (two 1/4-inch thick panes with a 1/2-inch airspace) typically achieve an STC rating of approximately 32. It is important to note that the recommended STC ratings are for full window assemblies (glass-andframe) rather than just the glass itself. Tested sound-rated assemblies should be used. If non-tested assemblies were to be used, the STC rating of the glass would likely need to be increased. The California Building Code (CBC) requires that where windows need to be closed to achieve an indoor DNL of 45 db, an alternative method of supplying fresh air (e.g., mechanical ventilation) must be provided. This applies to all of the multi-family residences with sound-rated window assemblies. This issue should be discussed with the project mechanical engineer. Exterior Noise To meet the City s exterior noise goal of DNL 65 db for the outdoor open space, no mitigation is needed. The new residences and existing structures surrounding the site are expected to provide enough shielding to this area to reduce the noise level to DNL 65 db or below. * * * This concludes our environmental noise study for the Sunset Office Plaza. Should you have any questions, please give us a call. Sincerely, CHARLES M. SALTER ASSOCIATES Shanna M. Sullivan Consultant Jeremy L. Decker Principal Consultant 3 Sound Transmission Class (STC) A single-figure rating standardized by ASTM and used to rate the sound insulation properties of building partitions. The STC rating is derived from laboratory measurements of a particular building element and as such is representative of the maximum sound insulation. Increasing STC ratings correspond to improved noise isolation.

15 L1: DNL 63 db L2: DNL 65 db

16