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HomeMy WebLinkAboutCDP 12-13; Zephyr Court Subdivision; Coastal Development Permit (CDP) (2)RECEIVED OCT 0 9 2007 CITY OF CARLSBAD PLANNING DEPT STRUCTURAL ACOUSTICAL ANALYSIS / CCR TITLE 24 SURVEY BLACK RAIL ROAD ESTATES CARLSBAD, CA Submitted to: Trans West Housing, Inc. Paul O'Boyle 10721 Treena Street, Suite 200 San Diego, CA92131 Prepared by: Investigative Science and Engineering, Inc Scientific, Environmental, and Forensic Consultants 16486 Bernardo Center Drive, Suite 278 San Diego, California 92128 (858) 451-3505 www.ise.us ISE Project #07-064 October 8, 2007 ACOUSTICS - VIBRA TION -AIR QUALITY-TRAFFIC IMPACT ASSESSMENTS - FORENSIC ENGINEERING EXPERT WITNESS - ENVIRONMENTAL ASSESSMENTS AND COMPLIANCE INTRODUCTION AND DEFINITIONS Existing Site Characterization The project site consists of approximately 5.6 acres located within the City of Carlsbad. The project site is located east of Interstate 5 (1-5) and approximately %-mile south of Poinsettia Lane along Black Rail Road. 1-5 via Poinsettia Lane provides regional access to the project area as can be seen in Figure 1 below. I y v^^_» \ r^i-\ ill I ' •» . ^ • u 0 % '/4 1 1% FIGURE 1: Project Vicinity Map (ISE 6/07) © 2007 investigative Science and Engineering, Inc. The leader in acoustics and vibration... Structural Acoustical Analysis / CCR Title 24 Survey Black Rail Road Estates - Carlsbad, CA ISE Report #07-064 October 8, 2007 Page 2 The site has a relatively constant downhill slope from west-to-east, with elevations ranging between approximately 380 feet above mean sea level (MSL) to roughly 320 feet MSL along the northeastern boundary as indicated in Figure 2 below. /// 0 400 800 1200 1600 2000 FIGURE 2: Project Site Location Map w/ Topography (ISE 6/07) ) 2007 investigative Science and Engineering, Inc. The leader In acoustics and vibration... structural Acoustical Analysis / CCR Title 24 Survey Black Rail Road Estates - Carlsbad, CA ISE Report #07-064 October 8, 2007 Page 3 Project Description The project proposes the construction of sixteen (16) new single-family residential lots within the aforementioned 5.6-acre project site. The project will have livable areas consistent with the above residential zoning requirements. The current site development plan is shown below in Figure 3 below. PROJECT SrrE PLAN If : ./ / X J / =^ il ; 1 (!' ew** 1 ,! [ f Ml 1 11 : 1 > ^ ^ tni' 1 1 «* 11 li<. f ^ < 1 i n' ' " 'S-Wvi, 1 ' ' "^1 III ->".•> 'ifit li i0rjj 'I' FIGURE 3: Proposed Black Rail Road Site Plan (Excel Engineering, Inc., 2006) Acoustical Definitions Noise is generally defined as unwanted or annoying sound that is typically associated with human activity and which interferes with or disrupts normal activities. Although exposure to high noise levels has been demonstrated to cause hearing loss, the principal human response to environmental noise is annoyance. The response of individuals to similar noise events is diverse and influenced by the type of noise, the perceived importance of the noise and its appropriateness in the setting, the time of day and the type of activity during which the noise occurs, and the sensitivity of the individual. © 2007 investigative Science and Engineering, Inc. The leader In acoustics and vibration... structural Acoustical Analysis / CCR Title 24 Survey Black Rail Road Estates - Carlsbad, CA ISE Report #07-064 October 8, 2007 Page 4 Airborne sound is a rapid fluctuation of air pressure above and below atmospheric pressure. Sound levels are usually measured and expressed in decibels (dB). Most of the sounds one hears in the environment do not consist of a single frequency, but rather a broad band of frequencies differing in level. The intensities of each frequency add to generate sound. The method commonly used to quantify environmental sounds consists of evaluating all of the frequencies of a sound according to a weighting system that reflects the fact that human hearing is less sensitive at low and extremely high frequencies than at the mid-range frequencies. This is called "A" weighting, and the decibel level measured is called the A-weighted sound level (dBA). In practice, the level of a noise source is conveniently measured using a sound level meter that includes a filter corresponding to the dBA curve. Although the A-weighted sound level may adequately indicate the level of environmental noise at any instant in time, community noise levels vary continuously. Most environmental noise includes a conglomeration of noise from distant sources that create a relatively stable background noise in which no particular source is identifiable. A single descriptor called the Leq (or equivalent sound level) is used. Leq is the energy- mean A-weighted sound level during a measured time interval. It is the 'equivalent' constant sound level that would have to be produced by a given source to equal the fluctuating level measured. Another sound measure employed by the State of California and the City of San Diego is known as the Community Noise Equivalence Level (or CNEL) is defined as the "A" weighted average sound level for a 24-hour day. It is calculated by adding a 5- decibel penalty to sound levels in the evening (7:00 p.m. to 10:00 p.m.), and a 10- decibel penalty to sound levels in the night (10:00 p.m. to 7:00 a.m.) to compensate for the increased sensitivity to noise during the quieter evening and nighttime hours. Finally, a sound insulation parameter known as the Sound Transmission Class (or STC) of a wall, window, or ceiling assembly is defined as the acoustic transmission of a structural assembly at a frequency of 500 Hertz with respect to a reference transmission curve. The use of a single-number transmission rating (such as the STC) correlates in a general way with subjective impressions of sound transmission for speech, radio, television, and similar sources of noise in buildings. The "reference curve" to which the actual transmission is compared, is based upon the above noise sources. The STC rating can be used to compare the potential sound insulation of structural assemblies tested in a laboratory or between different rooms in a building. The rating for a partition built and tested in a building may be lower than that obtained for a partition tested in a laboratory because of flanking transmission and construction errors. Typical STC ratings and their effectiveness are shown in Table 1 on the following page. ' f •' ' /' i •' ® 2007 Investigative Science and Engineering, Inc. £. A* • tThe leader in acoustics and vibration... Structural Acoustical Analysis / CCR Title 24 Survey Black Rail Road Estates - Carlsbad, CA ISE Report #07-064 October 8, 2007 Page 5 TABLE 1: Common STC Ratings and Insulation Effectiveness STC Rating Privacy Afforded 25 Normal speech understood at close distances 30 Normal speech audible, but unintelligible 35 Loud speech understood 40 Loud speech audible, but unintelligible 45 Loud speech barely audible 50 Shouting barely audible 55 Shouting not audible GENERAL APPROACH AND METHODOLOGY The analysis methodology used to examine sound transmission and resultant interior noise levels is identified in the American Society of Testing and Materials (ASTM) guidelines Volume 04.06 entitled, "Thermal Insulation; Environmental Acoustics" Test Designation: E 413-87. Acoustical modeling of the project was performed in accordance with the above guidelines and included corrections for the following parameters: o Exterior noise level adjustment in front of each building element, o Extenor noise spectrum placement in front of each building element, o Correction for building facade reflection (per ASTM E 966-84). o Incident angle source correction (per ASTM E 966-84). o Room absorption correction. o Building element correction and adjustment (per ASTM E 413-87). o Geometric (sizing) and workmanship (construction error) corrections. The exterior noise level at the proposed structures are calculated in terms of decibels A-weighted (dBA) and converted to six octave band sound pressure levels at: 125, 250, 500, 1000, 2000 and 4000 Hertz. The interior noise level is a function of the sound transmission loss qualities of the construction material and the surface area of each element (wall, window, door, etc.). The interior noise level also depends upon the room's sound absorption characteristics (in Sabins). '::'•'/ i ® 2007 Investigative Science and Engineering, Inc. >[ ' " / The leader in acoustics and vibration... Structural Acoustical Analysis / CCR Title 24 Survey Black Rail Road Estates - Cadsbad, CA ISE Report #07-064 October 8, 2007 Page 6 Mathematically, this can be expressed in the form of Equation 1 below: L.=L-TL.-mog,JS)-mog^JA.) + F -A +Q (1) intj ext. I '^10^ 1-' corr corr ^corr ^ ' where, L.^^ is the interior A-weighted sound level at the i"^ octave band, L^^ is the exterior A-weighted sound level at the i"^ octave band, TL. is the sound transmission loss at the i* octave band, S is the size of the room fagade in square feet, A. is the total room absorption in Sabins at the i"' octave band, and, F .A ,0 are correction factors for the building facade reflection, incident corr' corr' ^corr ^ ' angle, and construction quality. ISE assumed that the exterior noise levels were calculated for free-field conditions with no interaction between existing structures. A 3-dBA building facade reflection correction was applied to the as-built structure to simulate local reflection effects. The necessary calculations were performed using the ISE STC-Calc 5.7 interior noise computation program. APPLICABLE NOISE STANDARDS The California Code of Regulations (CCR), State Building Code, Part 2, Title 24, Appendix Chapter 35; "Noise Insulation Standards for Multifamily Housing requires that multi-family dwellings, hotels, and motels located where the CNEL exceeds 60 dBA require an acoustical analysis showing that the proposed design will limit interior noise to less than 45 dBA CNEL. Worst-case noise levels, either existing or future, must be used. Future noise levels must be predicted at least ten years from the time of building permit application. The City of San Diego has adopted the CCR Title 24 regulations for all types of residential dwellings. PREDICTED EXTERIOR NOISE LEVELS The primary source of future noise at the project site would be from vehicular traffic associated with Adams Avenue and Marlborough Drive. The worst-case exterior noise levels were identified in the projects acoustical site assessment prepared by Investigative Science and Engineering (ISE Report #03-065 Acoustical Site Assessment). Based upon the findings of the earlier assessment, identified future worst-case traffic related noise levels at the project site could be as high as 62.5 dBA for second floor areas on either Lots 1 or -16 for second floor areas only. First floor areas on these lots were less then 60 dBA and would not require special windows to comply with CCR Title 24. , /; . '/ i '—y © 2007 Investigative Science and Engineering, inc. / ,v 'J )( c::/ The leader In acoustics and vibration... Structural Acoustical Analysis / CCR Title 24 Survey Black Rail Road Estates - Carlsbad, CA ISE Report #07-064 October 8, 2007 Page 7 CONSTRUCTION ASSUMPTIONS The following general construction assumptions were applied to each of the units to determine their sound insulation characteristics: o The roof/ceiling construction should have a minimum STC rating of 46. o All living spaces examined (i.e., living rooms and bedrooms) were assumed to have carpet and pad (i.e.. Floor Multiplication Parameter or FMP = 0.8) for the purposes of STC calculation. o Bathroom, kitchen, and closet areas were not examined and thus have no construction limitations. The surface areas and materials for the proposed project were obtained from architectural drawings prepared by The McKinley Associates dated 8/07. When the interior noise level was found to be greater than 45 dBA CNEL, the value was recalculated for a closed window condition. Further recalculation was done to determine the minimum window-glazing requirement. Construction practices may degrade the calculated acoustical performance of walls and window assembles. The interior noise levels have been predicted in accordance with generally accepted acoustical methods and assume good construction techniques. FINDINGS Based upon the model results, the estimated interior noise levels would be as high as 58.0 dBA CNEL with the windows open and would require a closed window condition to comply with the CCR Title 24 requirements. Mechanical ventilation (i.e. HVAC Equipment) would be required (per the confines of CCR Title 24) and would be required to meet specific City of Carlsbad building requirements. The acoustical treatments (STC ratings) for the proposed Black Rail Road Estates development are summarized in Table 2 below and would be applicable with all units. The complete modeled results are provided as an attachment to this report. TABLE 2: Structural Acoustical Requirements - Commercial and Penthouse Floor Areas Room Building Element STC Rating All Rooms/All Units Roof/ Wall Assembly 46 All Glass Doors 20 All Glass Window Assemblies 20 Source: ISE STC-Calc 5.7 ) 2007 Investigative Science and Engineering, Inc. The leader in acoustics and vibration... Structural Acoustical Analysis / CCR Title 24 Survey Black Rail Road Estates - Carlsbad, CA ISE Report #07-064 October 8, 2007 Page 8 CERTIFICATION OF ACCURACY AND QUALIFICATIONS This report was prepared by Investigative Science and Engineering, Inc. (ISE) located at 16486 Bernardo Center Drive, Suite 278, San Diego, CA 92128. The members of its professional staff contributing to the report are listed below: Rick Tavares B.S. Aerospace Engineering / Engineering Mechanics (rtavarest^ise.us) M.S. Mechanical Engineering M.S. Structural Engineering Ph.D. Civil Engineering Andre Estrada B.S. Mechanical Engineering (aesfrada@;se.us^ ISE affirms to the best of its knowledge and belief that the statements and information contained herein are in all respects true and correct as of the date of this report. Should the reader have any questions regarding the findings and conclusions presented in this report, please do not hesitate to contact ISE at (858) 451-3505. Content and information contained within this report is intended only for the subject project and is protected under 17 U.S.C. §§ 101 through 810. Original reports contain non-photo blue ISE watermark at the bottom of each page. Approved as to Form and Content: Rick Tavares, Ph.D. Project Principal Investigative Science and Engineering, Inc. Attachments to this report: Interior Noise Calculation Spreadsheet I ©2007 Investigative Science and Engineering, Inc. }\ The leader In acoustics and vibration... 1 Room Type: Roor Area: Ceiling Height: Room Volume: FMP: Room Absorption (Sabins): Noise Source: Level e Fagade (dBA CNEL): Incident Angle Correction: Building Facade Comsction: Quality Correction: Assembly « 1 2 3 Plan 3 - Master Bedroom - Roor 2 441 8 3528 0.8 352.8 Traffic (NBS Spectmm, 1978) 62.5 -3 3 1 Construction Stucco Wall (NBS W-50-71) Window • 3'32 Glass (NBS W-23-72) Window - 3^ Glass (NBS W-23-72) STC Rating 46.0 20.0 20.0 Operable % 0.0 50.0 50.0 Area <sq-ft) 345.5 25.0 10.0 Contribution (dBA) (Closed) (Open) 26.7 42.0 38.0 26.7 50.7 46.7 Sliding Glass Door - 3/16 Glass (Monsanto) 20.0 50.0 37.5 35.9 46.2 Construction Stuooo Wall (NBS W-50-71) Window - 3/32 Glass (NBS W-23-72) Window - 3/32 Glass (NBS W-23-72) 125 Hz 27.0 15.0 15.0 250 Hz 42.0 14.0 14.0 Sum (Z): 44.2 53.1 500 Hz 44.0 17.0 17.0 1000 Hz 46.0 19.0 19.0 2000 Hz 49.0 23.0 23.0 4000 Hz 54.0 21.0 21.0 Sliding Glass Door - 3/16 Glass (Monsanto) 16.0 18.0 21.0 22.0 23.0 24.0 2 Room Type: Roor Area: Ceiling Height: Room Volume: FMP: Room Absorption (Sabins): Noise Source: Level @ Facade (dBA CNEL): Incident Angle Correction: Building Fa^de Conectlon: Ouality Con^ction: Assembly* 1 2 3 Plan 3 - Master Bedroom Opt 2 - Floor 2 441 8 3528 0.8 352.8 Traffic (NBS Spectmm, 1978) 62.5 -3 3 1 Construction Stucco Wall (NBS W-50-71) Window - 3/32 Glass (NBS W-23-72) Window - 3/32 Glass (NBS W-23-72) Contribution (dBA) STC Rating Operable % Area(sq-n) (Closed) (Open) 46.0 0.0 345.5 26.7 26.7 20.0 50.0 25.0 42.0 50.7 20.0 50.0 10.0 38.0 46.7 French Door - 3/32 Glass (NBS W-94-71) 20.0 100.0 37.5 37.3 56.8 Construction Stucco Wall (NBS W-50-71) Window - 3/32 Glass (NBS W-23-72) Window - 3/32 Glass (NBS W-23-72) 125 Hz 27.0 15.0 15.0 250 Hz 42.0 14.0 14.0 Sum (S): 44.4 58.0 500 Hz 44.0 17.0 17.0 1000 Hz 46.0 19.0 19.0 2000 Hz 49.0 23.0 23.0 4000 Hz 54.0 21.0 21.0 French Door - 3/32 Glass (NBS W-94-71) 15.0 18.0 21.0 21.0 18.0 22.0 3 Room Type: Roor Area: Ceiling Height: Room Volume: FMP: Room Absorption (Sabins): Plan 3 - Bedroom 3 - Floor 2 232.5 8 1860 0.8 186 Noise Source: Level e Facade (dBA CNEL): Incident Angle Conectlon: Building Facade Correction: Quality ConecUon: Traffic (NBS Spectmm, 1978) 62.5 -3 3 1 Contribution (dBA) AssemtMy * Construction STC Rating Operable % Area (sq-tt) (Closed) (Open) 1 Stucco Wall (NBS W-50-71) 46.0 0.0 220.5 27.6 27.6 2 Window • 3/32 Glass (NBS W-23-72) 20.0 50.0 7.5 37.7 46.4 3 Window - 3/32 Glass (NBS W-23-72) 20.0 50.0 4.5 37.3 46.0 4 Window - 3/32 Glass (NBS W-23-72) 20.0 50.0 15.0 37.7 46.4 1 Sum (I): 42.5 51.1 1 Construction 125 Hz 250 Hz 500 Hz 1000 Hz 2000 Hz 4000 Hz Stucco Wall (NBS W-50-71) 27.0 42.0 44.0 46.0 49.0 54.0 Window - 3/32 Glass (NBS W-23-72) 15.0 14.0 17.0 19.0 23.0 21.0 Window - 3/32 Glass (NBS W-23-72) 15.0 14.0 17.0 19.0 23.0 21.0 Window - 3/32 Glass (NBS W-23-72) 15.0 14.0 17.0 19.0 23.0 21.0 4 Room Type: Roor Area: Ceiling Height: Room Volume: FMP: Room Absorption (Sabins): Noise Source: Level e Facade (dBA CNEL): Incident Angle Correction: Building Facade Correction: Quality Connection: Assembly # 1 2 3 Plan 3 - Bedroom 2 - Floor 2 168 8 1344 0.8 134.4 Traffic (NBS Spectmm, 1978) 62.5 -3 3 1 Construction Stucco Wall (NBS W-50-71) Window - 3/32 Glass (NBS W-23-72) Window - 3/32 Glass (NBS W-23-72) Contribution (dBA) STC Rating Operable % Area(sq-n) (Closed) (Open) 46.0 0.0 133.5 26.8 26.8 20.0 50.0 15.0 42.2 50.9 20.0 50.0 4.5 33.9 42.6 Construction Stucco Wall (NBS W-50-71) Window - 3/32 Glass (NBS W-23-72) Window - 3/32 Glass (NBS W-23-72) 125 Hz 27.0 15.0 15.0 250 Hz 42.0 14.0 14.0 500 Hz 44.0 17.0 17.0 Sum g): 1000 Hz 46.0 19.0 19.0 42.9 2000 Hz 49.0 23.0 23.0 51.5 I 4000 Hz 54.0 21.0 21.0