The URL can be used to link to this page

Home My WebLink AboutCT 02-07; EMERALD POINT ESTATES; ACOUSTICAL MONITORING SURVEY; 2000-05-05Investigative Science and Engineering 3545 Camino Del Rio South, Suite E San Diego, CA 92108-4003 May 5, 2000 Ms. Kristine Zortman Greystone Homes, Inc. 5780 Fleet Street, Suite 300 Carlsbad, CA 92008 PhonelFax: 619-640-9379/619-640-0763 www.investigative-science;cdm Re:. BCS Property Field Survey and Noise Assessment, Carlsbad, CA (ISE Report #00-023) Dear Ms. Zortman: At the request of Jack Henthorn & Associates, Investigative Science and Engineering (ISE) has performed an acoustical monitoring survey to ascertain potential noise impacts to the BCS property located in the City of Carlsbad due to flight operations from nearby McClellan Palomar Airport. Specifically, this study was performed to verify the location of the 65 dBA CNEL noise contour as it pertains to the current d~velopment configuration. The results of that survey are presented in this letter report. Introduction and Definitions Existing Site Characterization The BCS development is located within the City of Carlsbad approximately 1 mile southwest from the McClellan Palomar Airport (refer to Figure 1 below). Currently, the site resides as fallow agriculture/undeveloped open space and is bordered to the north by Palomar Airport Road, to the east and south by residential development, and to the west by residential development. The primary concern is the location ,of the 65 dBA CNEL noise contour as published in the Noise Element of the City of Carlsbad General Plan arid in the Federal Air Regulations (FAR) Part 150 Noise Compatibility Program for McClellan Palomar Airport. The current site configuration and location of the published 65 dBA CNEL noise contour is shown below in Figure 2. Ms. Kristine Zortman BCS Property Field Survey and Noise Assessment, Carlsbad, CA ISE Report #00-023 MayS, 2000 Page 2 Figure 1: Project Vicinity Map (Thomas Guide Page 1127, Grid, 83) 1 J c-Flight Activity Zone Existing Property J.-~ ~____ Une _---~ ---I __ .----.-~ ----\1 ----.-I r "", 1\ 5 Proposed Property Line ! -,_ 1\ I 65 CNEL Noise Contour ---., ;x. .. ~ ........... -........... ,,,,,,, ........... .. i ~.~ ..... i\~\l I _____ ! "-. I \ \ .................. ~ ....... y'/ / \"~:. . r-~-/\--\;..7t:"'-.~----------------\ ."".............. ;.. " (, :".'': -1'" /,' CUmlnt Proposed , ··· .. r .......... · ...... · .. ·· / " "-.. .' " Ii· Development Configuratior \ / / •... ,/ (' '. ' / \~ \. \ /./ \: .\ F /'-". E ~ \ :\ ",f ':::"," S ~\ Existing "''''. ~Z .. _ MarSrisa ~h ~, /'" .~". ~ -.~" ' 'S :.....z. / / ~-.--/-~~ '" , ! :' '~7 ,-'-.::.::--""'-...,, .? . / . Figure 2: 8CS Property Site Development Configuration Ms. Kristine Zortman BCS Property Field Survey and Noise Assessment, Carlsbad, CA ISE Report #00-023 MayS, 2000 Page 3 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 sensitivity of the individual hearing the sound. Airborne sound is a rapid fluctuation of air pressure above and below atmospheric levels. The loudest sounds the human ear can hear conformably are approximately one trillion (a one with 12 zeros following it) times the acoustic energy that the ear can barely detect. Because of this vast range, any attempt to represent the acoustic intensity of a particular sound on a linear scale becomes unwieldy. As a result of this, a logarithmic ratio known as the decibel (dB) is commonly employed. A sound level of zero "0" dB is scaled such that it is defined as the threshold of hearing and would be barely audible to a human of normal hearing under extremely quiet listening conditions and would correspond to a sound pressure level equal to the reference level. Most of the sounds we hear in the environment do not consist of a single frequency, but rather a broad band of frequencies differing in sound level. The intensities of each frequency add to generate the sound we hear. The method commonly used, to quantify environmental sounds consists of determining all of the frequenCies of a sound according to a weighting system that reflects the nonlinear response characteristics of the human ear. This is called "A" weighting, and the decibel level measured is called the A-weighted sound level (or 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 sounds from distant sources that create a relatively steady background noise in which no particular source is identifiable. For this type of noise 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. For most environmental acoustical studies, the monitoring interval is generally taken as one-hour and is abbreviated as Leq-h. Finally, a sound measure employed by the State of California is known as the Community Noise Equivalence Level (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 I I Ms. Kristine Zortman BCS Property Field Survey and Noise Assessment, Carlsbad, CA ISE Report #00-023 May 5, 2000 Page 4 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. The published aircraft noise contours for the McClellan Palomar Airport are given in units of CNEL and are not a function of local topography. Ambient Noise Monitoring Methodology A single Larson Davis Model 700 ANSI Type \I integrating sound level meter was used as the data collection device. The meter was mounted to a tripod approximately five feet above the ground and was placed onsite at a location corresponding to the published crossing point of the 65 dBA CNEL noise contour. The location of the meter is shown below in Figures 3 and 4. The meter logged data and was operational from 3/17/00 through 3/27/00 (approximately two-weeks) in order to quantify actual existing community noise levels (Le., the site CNEL value). . All sound measurement equipment was calibrated before and upon completion of the testing. All sound measurement equipment was within the valid manufacturers calibration period. Figure 3: Two-week Noise Monitoring Setup -Bes Property Ms. Kristine Zortman BCS Property Field Survey and Noise Assessment, Carlsbad, CA ISE Report #00-023 May 5, 2000 Page 5 Palomar Airpor!~d .. --_. ----- Figure 4: Test Setup Relative to Existing 65 CNEL dBA Noise Contour ~ Findings The results of the two-week sound level monitoring are shown. graphically in Figure 5 (attached). Based upon the data collected during the monitoring period it was observed that the overall CNEL recorded at this site was 60.9 dBA. Based upon the ·field observations, the level observed was found to. be an aggregate of traffic noise along Palomar Airport Road and McClellan Palomar Airport. Due to the location of the monitoring equipment, the current traffic volume along Palomar Airport Road, and the observed headway between commuter aircraft, vehicular traffic noise along Palomar Airport Road was identified as the dominant noise source affecting the site. No unusual . traffic patterns were observed in the data from either the airport or Palomar Airport Road. The measured levels are consistent with the observed community setting. Since the aggregate of traffic and aircraft noise did not exceed 65 dBA CNEL, there is no physical way that the aircraft-only contribution could exceed this level. Thus, the measured project test location does not empirically reside within the 65 dBA CNEL contour of McClellan Palomar Airport. Ms. Kristine Zortman BCS Property Field Survey and Noise Assessment, Carlsbad, CA ISE Report #00-023 May 5, 2000 Page 6 Should you have any questions regarding the above conclusions, please do not hesitate to contact me at (619) 640-9379. Sincerely, R.ick Tavares, REA, INeE Project Principal Investigative Science and Engineering SPL in dBA ." ii' e .., CD (JI III n en -f » 3' 3 tD C" S' Q. 3/22100 2:30 PM (6' tD ~ >< .... Z 3/23/00 2:30 AM 0 '-, tn CD 3/23/00 2:30 PM "0 .. 0 .... _. 3/24/00 2:30 AM CD 3/24/00 2:30 PM 3/25/00 2:30 AM 3/25/00 2:30 PM 3/26/00 2:30 AM ,t 3/26/00 2:30 PM 3/27/002:30 AM 3/17'002:30 PM ~ 3/22100 2:30 AM 3' m S" 3/22'00 2:30 PM C-~ 3/23'00 2:30 AM 3/23/00 2:30 PM . 3/24/00 2:30 AM 3/24/00 2:30 PM 3/25'00 2:30 AM 3/25/00 2:30 PM 3i26/00 2:30AM 3/26'00 2:30 PM 3/27/002:30 AM ~ e ~ .jl. o SPL in dBA .jl. CJ1 C1I o C1I C1I C> o ~ <;.~- • ~"W' "'W~;:"'''' e C> C1I ....s o OJ 0 en » 3 C" _. CD ~ .... Z O _. en CD "'0 .., 0 ..... _. -CD "- 3117100 2:30 PM 3/18100 2:30AM 2:30 PM 3/19/00 2:30AM -I 3" CI) :l Q. 2:30 PM CI) ,)( 3120100 2:30AM 2:30 PM 3121100 2:30AM SPL in dBA OJ 0 en » 3 C-_., CD ::l .... Z 0 _. t/J CD -C .., 0 -It _. -CD