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HomeMy WebLinkAbout1996-10-02; Planning Commission; ; CUP 93-02A - POINSETTIA COMMUTER RAIL STATIONf ne City of CARLSBAD Planning Departme! .. A REPORT TO THE PLANNING COMMISSION P.C. AGENDA OF: October 2, 1996 ltemNo.@ Application complete date: n/a Project Planner: Christer Westman Project Engineer: Ken Quon SUBJECT: CUP 93-02(A) -POINSETTIA COMMUTER RAIL STATION -Withdrawal of staffs request for a Conditional Use Permit Amendment and report on status of compliance with conditions of approval. I. RECOMMENDATION That the Planning Commission conduct the public hearing, note and file the staff report, and take no action regarding the proposed amendment of CUP 93-02. II. INTRODUCTION This item is a review of an existing Conditional Use Permit and the applicant's compliance with its conditions of approval. CUP 93-02 was discussed by the Planning Commission in May of 1996 because there were complaints regarding the operation of the commuter rail station and the unresolved issue regarding physical buffering of the noise and light generated by the project. Appropriate forms of physical buffers to soften those impacts were also discussed. The intention of this report is to apprise the Planning Commission that staff has determined the information provided by North San Diego County Transit Development Board (NSDCTDB) demonstrates compliance with the conditions of the CUP approval. III. PROJECT DESCRIPTION AND BACKGROUND The Poinsettia Commuter Rail Station was approved by the Planning Commission in May of 1994 by Conditional Use Permit 93-02 for a period of three years. Condition number eight of Planning Commission Resolution No. 3643 required NSDCTDB to prepare and submit a noise study to the City, and further to comply with the Planning Director's determination regarding the provision of "physical buffering, including noise walls if necessary" between the Lanikai Lane Mobile Home Park and the commuter rail platform. This item was heard by the Planning Commission on May 1, 1996 and was continued to August 7, 1996. The continuance was directed so that NSDCTDB could complete a noise study and discuss potential mitigation measures, if necessary, with Planning Staff. Staff requested that the item be further continued until the September 4, 1996 meeting because NSDCTDB submitted the noise study at a date that did not allow sufficient time to review the documents, discuss the issues with the Lanikai Lane residents, reach a conclusion with NSDCTDB and present the findings in a staff report to the Planning Commission. Staff requested an additional continuance to this ( ( CUP 93-02(A) -POINSET11A COMMUTER RAIL STATION OCTOBER 2, 1996 PAGE2 October 2 meeting because discussions were still ongoing with NSDCTDB and Lanikai Lane Mobile Home Park residents. Staff has concluded discussions with NSDCTDB and has determined that they are now in compliance with Condition No. 8 required by the CUP and consequently there is no need to amend the conditions of approval. Staff is, therefore, recommending withdrawal of CUP 93- 02(A) and has come before the Planning Commission with this status report. IV. ANALYSIS 1. Noise NSDCTDB was directed to prepare a noise study to determine if physical buffering should include a noise wall. A noise study, Exhibit "B", was completed by Mestre Greve Associates which identified the noise levels generated by the operation of the commuter rail as well as the operation of Amtrak and the freight service using the same rails. By calculating the Community Noise Equivalent Level (CNEL) attributable to the commuter rail operations, a baseline noise level of 61. 5 CNEL has been determined to have existed prior to the construction of the commuter rail station. This exceeds the City's accepted residential standard by 1.5 CNEL. The cumulative addition of the commuter rail operation, Monday through Thursday, increases the CNEL by 2.2. The addition of CNEL by the commuter rail station on Fridays, is 3.0 CNEL. The additional CNEL on Fridays is due to a greater number of train trips. So, as a worst case on Fridays, the CNEL has been raised from 61.5 to 64.5 CNEL. As stated in the Master Greve noise study, changes in noise levels greater than 3 dB are often identified as significant, while changes less than 1 dB will not be discernible to local residents. In the range of 1 to 3 dB, residents who are very sensitive to noise may perceive only a slight change. It should be noted that there is no scientific evidence available to support the use of 3 dB as the significance threshold. In laboratory testing situations, humans are able to detect noise level changes of slightly less than 1 dB. In a community noise situation, however, noise exposures are over a long time period, and changes in noise levels occur over years, rather than the immediate comparison made in a laboratory situation. Therefore, the level at which changes in community noise levels become discernible is likely to be some value greater than 1 dB, and 3 dB appears to be appropriate for most people. Staffs recommendation not to require noise attenuation is based on the information provided in the noise analysis. Regardless of the results of the technical noise study, and the determination that noise decibels are within acceptable levels, NSDCTDB has stated that, to the greatest extent possible within safety norms, engineers of the commuter rail trains will be requested to minimize the use of bells and horns while approaching, standing and departing the station to reduce the noise effects. In addition Amtrak has been contacted regarding the use of horns in proximity to Lanikai Lane Mobile Home Park. It should be noted that as traffic ( commuter rail, Amtrak and freight) increases along this rail right-of-way, so will noise levels. It would be appropriate to monitor the frequency of events CUP 93-02(A)-POINSE;~;A COMMUTER RAIL STATION ( OCTOBER 2, 1996 PAGE3 along the rail right-of-way to determine at what point noise attenuation is appropriate and to include such a condition when the project is being reviewed for any future amendment. (See discussion below) 2. Light: The requirement for physical buffering, Condition No. 8 of Planning Commission Resolution No. 3643, was not only to address impacts but also to address light impacts. Lights within the station area have some overspill which in turn affects some residents within the Lanikai Lane Mobile Home Park. Staff has been at the park for evening meetings with the residents and has verified this fact. Staff has therefore determined that landscaping would be an appropriate physical buffer along the western most edge of the commuter rail property. With maturity of the trees, light overspill will be reduced. In addition to landscaping, adjusting and shielding the existing lights will further reduce light overspill. NSDCTDB has agreed to do both. Both planting and light standard shielding were discussed with the residents of Lanikai Lane Mobile Home Park. Most, but not all, of the affected residents along the eastern side of the park were interested in having landscape installed between Lanikai Lane and the commuter rail platforms. It was suggested that those interested residents along the eastern edge of the mobile home park have the opportunity to provide input into the landscape scheme along the eastern boundary of the park. A committee has been formed to include the City, residents of the park and representatives from NSDCTDB. There was no opposition to light shielding. 3. Future Amendment To Cup 93-02 Condition number 13 of Planning Commission Resolution No. 3643 required any increase to the number of train trips and any change to the facilities along the platforms be reviewed by the Planning Commission as a CUP amendment. NSDCTDB has increased its schedule of operations to include train trips on Friday nights and Saturdays and has also installed loudspeakers at the train platform. NSDCTDB has submitted an application for a CUP amendment to address these items. The amendment will be brought to the Planning Commission as a separate item at a forthcoming meeting. Any additional environmental impacts that may arise will be addressed at the time of the CUP amendment. 4. Summary The noise analysis provides evidence that the noise levels produced by the commuter rail station and measured as Community Noise Equivalent Level (CNEL) is within acceptable levels. The analysis also indicates that the cumulative increase in CNEL is below a significant level. Therefore, no noise mitigation is required. Tree planting will be required as a means of providing a physical separation from the train right-of-way as well as reducing the amount of light overspill to Lanikai Lane Mobile Home Park. CUP 93-02(A) -POINSET(~A COMMUTER RAIL STATION ( OCTOBER 2, 1996 PAGE4 IV. ENVIRONMENTAL REVIEW The project was reviewed previously and was approved in compliance with CEQA regulations through certification of an Environmental Impact Report and a notice of prior compliance. No action will be taken which requires any additi.onal review under CEQA. ATTACHMENTS: 1. Location Map 2. Noise Assessment Study dated August 26, 1996. CW:kr ( ( POINSETTIA COMMUTER RAIL STATION CUP 93-02 ( ( ~··--: /\ ")I':" ')')),,-<,0<8~ ,o.,··' .... >~ ~ i9~ 'e ~ m ~ co _. ... I ~ ~ ~ 14 4 o!'t o.,''> c?'ltto~G~l,. NOISE ASSESSMENT OF THE NCTD "COASTER" OPERATIONS AT THE LAN/KAI LANE MOBILE HOME PARK, CITY OF CARLSBAD July 10, 1996 Revised August 21, 1996 Report #96-106,A Prepared For: North County Transit District 311 South Tremont Street Oceanside, CA 92504 Prepared By: Fred Greve, P.E. Mike Holritz Mestre Greve Associates 280 Newport Center Drive, Suite 230 Newport Beach, CA 92660 (714) 760-0891 ( ( Lanikai Lane Noise Study Mestre Greve Associates Page 1 NOISE ASSESSMENT OF THE NCTD "COASTER" OPERATIONS AT THE LANIKAI LANE MOBILE HOME PARK, CITY OF CARLSBAD Summary Noise measurements were made at two sites at the La.nikaiMobileHome Parkover a24 hour period. The measurements indicate that the maximum sound levels are greater for the Amtrak trains than for the Coaster trains. However, the total acoustic energy for the Coaster trains is higher at the xx end of the mobile home park, while the Amtrak has a higher total acoustic energy when measuring at the opposite end of the park. For the measurementperiod, the Coaster trains added between 0.7 and 2.2 dBA to the total CNEL noise level. During this periodfreight train operations did not occur. If freight train operations had occurred, then the contribution attributable to the Coaster trains would be even less. The noise levels at the LanikaiMobile Home Park are above the City's criteria limit for new development of 60 CNEL. The noise levels during the measurement period were in the 64 to 65 CNEL depending on the location in the park. In summary, the noise levels in the mobile home park are above what is normally considered acceptable in the City of Carlsbad, however, the Coaster trains are only contributing a small amount to these levels. Introduction Noise measurements of train noise were made at the LanikaiLane Mobile Home Park in-the City of Carlsbad. The purpose of the measurements and subsequent analysis was threefold: 1) Present measured train noise for each type of train 2) Determine change in noise level due to "coaster" operations 3) Determine if overall noise levels are acceptable The following report provides background information on noise scales and standards. It then addresses the three issues identified above. Noise Definitions and Assessment Criteria Sound is technically described in terms of the loudness (amplitude) of the sound and the frequency (pitch) of the sound. The standard unit of measurement of the loudness of sound is the decibel (dB). Since the human ear is not equally sensitive to sound at all frequencies, a special frequency-dependent rating scale has been devised to relate noise to human sensitivity. The A-weighted decibel scale (dBA) performs this compensation by discriminating against frequencies in a manner approximating the sensitivity of the human ear. Decibels are based on the logarithmic scale. The logarithmic scale compresses the wide range in sound pressure levels to a more usable range of numbers in a manner similar to the Richter Scale used to measure earthquakes. In terms of human response to noise, a sound 10 dBA ( ( Lanikai Lane Noise Study Mestre Greve Associates Page2 higher than another is judged to be twice as loud; and 20 dB A higher four times as loud; and so forth. Everyday sounds normally range from 30 dBA (very quiet) to 100 dBA (very loud). Noise level increases of less than 3 dBA are usually not considered significant. A noise level increase of 5 dBA will be readily noticeable to the human observer, although it will not be perceived as dramatically as a 10 dB A change. Examples of various sound levels in different environments are shown in Exhibit 1. Noise has been defined as unwanted sound and it is known to have several adverse effects on people. From these known effects of noise, criteria have been established to help protect the public health and safety and prevent disruption of certain human activities. This criteria is based on such known effects of noise on people as hearing loss (not a factor with community noise), communication interference, sleep interference, physiological responses and annoyance. Each of these potential noise impacts on people are briefly discussed in the following narratives: HEARING LOSS is, in general, not a concern in community noise problems. The potential for noise induced hearing loss is more commonly associated with occupational noise exposures in heavy industry or very noisy work environments with long term exposure. The Occupational Safety and Health Administration (OSHA) identifies a noise exposure limit of 90 dBA for 8 hours per day to protect from hearing loss. Noise levels in neighborhoods, even in very noisy airport environments near major international airports, are not sufficiently loud to cause hearing loss. COMMUNICATION INTERFERENCE is one of the primary concerns in environmental noise problems. Communication interference includes speech interference and activities such as watching television. Normal conversational speech is in the range of 60 to 65 dBA and any noise in this range or louder may interfere with speech. SLEEP INTERFERENCE is a major noise concern in community noise assessment and, of course, is most critical during nighttime hours. Sleep disturbance is one of the major causes of annoyance due to community noise. Noise can make it difficult to fall asleep, create momentary disturbances of natural sleep patterns by causing shifts from deep to lighter stages and cause awakening. Noise may even cause awakening which a person may or may not be able to recall. Extensive research has been conducted on the effect of noise on sleep disturbance. Recommended values for desired sound levels in residential bedroom space range from 25 · to 45 dBA with 35 to 40 dBA being the norm. The National Association of Noise Control Officials has published data on the probability of sleep disturbance with various single event noise levels. Based on experimental sleep data as related to noise exposure, a 7 5 dBA interior noise level event will cause noise induced awakening in 30 percent of the cases. PHYSIOLOGICAL RESPONSES are those measurable effects of noise on people which are realized as changes in pulse rate, blood pressure, etc. While such effects can be induced and observed, the extent is not known to which these physiological responses cause harm or are a sign of harm. Generally, physiological responses are a reaction to a loud short term noise such as a rifle shot or a very loud jet overflight. ANNOYANCE is the most difficult of all noise responses to describe. Annoyance is a very individual characteristic and can vary widely from person to person. What one person considers tolerable can be quite unbearable to another of equal hearing capability. The level of annoyance, of course, depends on the characteristics of the ( ( Lanik:ai Lane Noise Study Mestre Greve Associates Page3 noise (i.e., loudness, frequency spectra, time, and duration), and how much activity interference (e.g. speech interference and sleep interference) results from the noise. However, the level of annoyance is also a function of the attitude of the receiver. Personal sensitivity to noise varies widely. It has been estimated that 2 to 10 percent of the population is highly susceptible to noise not of their own making, while approximately 20 percent are unaffected by noise. Attitudes are affected by the relationship between the person and the noise source. (Is it our dog barking or the neighbor's dog?) Whether we believe that someone is trying to abate the noise will also effect our level of annoyance. Noise Assessment Scales The description, analysis and reporting of community noise levels is made difficult by the complexity of human response to noise and the myriad of noise scales that have been developed for describing noise impacts. Each of these scales attempt to quantify noise levels with respect to community response. Community noise is generally not steady state and varies with time. Under conditions of non-steady state noise, some type of statistical metric is necessary in order to quantify noise exposure over a long period of time. Several rating scales have been developed for describing the effects of noise on people. They are designed to account for the previously described known effects of noise on people. Several rating scales have been developed for measurement of community noise. These account for: (1) the parameters of noise that have been shown to contribute to the effects of noise on man, (2) the variety of noises found in the environment, (3) the variations in noise levels that occur as a person moves through the environment, and ( 4) the variations associated with the time of day. They are designed to account for the known health effects of noise on people described previously. Based on these effects, the observation has been made that the potential for a noise to impact people is dependent on the total acoustical energy content of the noise. A number of noise scales have been developed to account for this observation. The predominant noise scale is the Community Noise Equivalent Level (CNEL). CNEL, Community Noise Equivalent Level, is the predominant rating scale now in use in California for land use compatibility assessment. The CNEL scale represents a time weighted 24 hour average noise level based on the A-weighted decibel. Time weighted refers to the fact that noise that occurs during certain sensitive time periods is penalized for occurring at these times. The evening time period (7 p.m. to lQ p.m.) penalizes noises by 5 dBA, while nighttime (10 p.m. to 7 a.m.) noises are penalized by 10 dBA. These time periods and penalties were selected to reflect people's increased sensitivity to noise during these time periods. A CNEL noise level may be reported as a "CNEL of 60 dBA," "60 dB A CNEL," or simply "60 CNEL." Typical noise levels in terms of the CNEL scale for different types of communities are presented in Exhibit 2. State laws require that cities develop their Noise Elements in terms of the Ldn or CNEL scales. Both of these scales represent time weighted 24 hour average noise, and correlate much better to how people perceive their noise environment. The California Department of Health has established guidelines for assessing the compatibility of community noise environments and land uses in terms of CNEL. The City of Carlsbad has adopted noise standards which require that new residential construction should be noise insulated so that the interior noise levels do not exceed 45 CNEL and that private outdoor living areas ( e.g., rear yards and patio areas) do not exceed 60 CNEL. These noise criteria are designed to minimize the impacts from transportation noise (i.e.; ( ( Lanikai Lane Noise Study Mestre Greve Associates Page4 traffic, aircraft, and trains) on residential land uses. Note that these noise standards do not necessarily apply to the mobile home park because they apply only to new residential developments. However, the standards are useful in evaluating the impact of the railroad noise on the mobile home park. It should be noted that the City's standard of 60 CNEL is 5 d.BA more stringent than the vast majority of communities. Most communities use 65 CNEL as their outdoor noise standard for residential development. There are no noise standards that are based solely on. the loudness of a single event. The Federal Aviation Administration (FAA) and some local communities have considered single event standards for aircraft noise. However, there are many technical reasons why these standards are not feasible, and none have been adopted. It should also be noted that there are no State, Federal, or City noise standards which apply specifically to train noise. Noise Measurement Survey Noise measurements were conducted from 2:00 p.m. on Tuesday, July 2 until 2:00 on Wednesday, July 3. Noise monitors were set up at both ends of the mobile home park. One monitor was located a Space 32 (Site B ), while the other was located at the playground area (Site A). The monitors used were Bruel & Kjaer Model 2236. These are ANSI Type 1 monitors and are the most accurate available for community noise measurements. The monitors were calibrated at the beginning and end of the measurement period with a calibrator which had current certification that is traceable to the National Bureau of Standards. The monitors were connected to "palmtop" computers to store the data acquired. Two types of measurements were of concern. The first category was the noise levels associated with individual train pass-bys. For these measurements a person had to be on site to identify what type of train passed by. For these events the monitor recorded the maximum sound level (Lmax), and the sound exposure level (SEL). The Lmax-is simply the instantaneous maximum sound level that is reached as the train passes by. The SEL represents the total acoustic energy of the train pass by compressed into one second. A loud, short train can have the same SEL value as a long, but quieter train. The SEL value is important because it is the value used for the calculation of the CNEL level due to the trains. The second type of measurement was the hourly noise level (often abbreviated as Leq). The hourly Leq noise levels are used to calculate total CNEL noise levels experienced at the mobile home park. Measured Train Noise for Each Type of Train Table 1 below shows the measured noise levels for each type of train. The manned noise measurements started at about 2:00 p.m. on Tuesday and went until about 8:00 p.m. They resumed on Wednesday at about 7:00 a.m. and went until 2:00 p.m. The monitor at Site A had some technical difficulties. The data stopped being recorded during the middle of the night. The monitor was revived for a couple hours in the morning and then failed again. Therefore, more train pass by data is available for Site B than for Site A. Twelve (12) Amtrak trains were visually identified, and fourteen (14) coaster trains. The measurement data for both sets of trains are fairly consistent, and therefore, the number of trains measured represent a good indication of their loudness. It should be noted that the monitors were not manned for the trains scheduled for 5:40 a.m., 6:22 a.m., and 6:48 a.m., and therefore are not included in Table 1. Similarly, the four additional trains scheduled for Friday are not included in Table 1. ( ( Lanikai Lane Noise Study Mestre Greve Associates Page5 The primary purpose of the data reported in Table 1 was to detennine the average noise levels for the Amtrak and Coaster trains. A sufficient number of trains were monitored during the manned periods to accomplish this goal. In all calculations of CNEL presented later in this report, the additional trains not observed during the manned periods are included in the CNEL noise levels. No freight trains were observed during the manned periods. Table 1 Noise Measurement Results for Individual Trains Site A Site B Time SEL LMAX SEL LMAX Amtrak Trains 2:42PM 89.4 83.6 93.3 87.0 3:20PM 90.5 83.8 95.3 87.9 4:34PM 90.0 84.9 93.9 88.5 5:15PM 87.7 81.2 91.8 84.6 6:57PM 91.6 84.1 93.1 85.0 7:16AM 87.3 80.2 92.7 84.9 8:29AM 92.9 86.3 9:16AM 95.0 88.7 10:50AM 93.3 87.3 11:17 AM 95.9 91.6 12:45PM 93.9 87.9 1:11 PM 93.2 87.1 Average 89.7 83.0 93.8 87 .2 Coaster Trains 3:07PM 90.6 76.4 85.3 76.2 3:51 PM 91.5 75.3 91.0 82.2 4:32PM 90.3 75.3 85.2 75.3 5:09PM 94.8 91.6 84.6 75.3 5:12PM 94.8 91.6 85.5 74.4 5:38PM 90.8 79.6 89.3 81.2 5:40PM 90.8 79.6 89.3 81.2 6:08PM 93.0 79.2 89.2 80.9 6:58PM 91.9 76.4 84.2 74.5 7:23PM 92.2 79.1 84.4 75.7 7:29AM 93.0 76.9 92.0 81.3 8:00AM 91.0 74.5 93.0 82.6 8:40AM 90.9 82.6 11:17 AM 93.6 89.4 Average 92.3 79.6 89.6 78.4 ( ( Lanikai Lane Noise Study Mestre Greve Associates Page6 The average Lmax and SEL values are presented for both sites for both types of trains. The Lmax represents the simple arithmetic average. SEL values must be average on a logarithmic basis. For Site A the SEL values are higher for the Coaster trains than for the Amtrak trains. For Site B this is reversed, with the Amtrak trains having higher SEL values than the Coaster trains. This is because Site A is directly across from the train station. The Coaster train events last much longer at Site A, and result in higher noise levels. For both sites the maximum sound levels were always higher for the Amtrak trains compared to the Coaster trains. The Amtrak trains usually used their horn near the mobile home park, and this was the cause of the Lmax values for the Amtrak trains. It should also be noted that the Coaster train makes extensive use of its bell. In talking with one resident, the bell on the Coaster train was his biggest complaint. Trains coming into the station ring the bell. No ringing of the bell occurs while the train is stopped at the station. Most Coaster trains also ring their bell as they depart the station. The North County Transit District should review the use of the bell, and if safety concerns allow, minimize the use of the bell. In summary, the instantaneous maximum sound level was much higher for the Amtrak trains than for the Coaster trains. This was due primarily to the fact that the Amtrak train usually used the whistle. The total acoustic noise as indicated by the SEL measurements were higher for the Coaster at Site A, and higher for the Amtrak at Site B. No freight trains were observed . . What is Change in Noise Level Due to Coaster Operations? The CNEL noise levels were determined for the 24 hour period lasting from 2 p.m. on Tuesday to 2 p.m. on Wednesday. The hourly noise levels are presented in Table 2. A weighting factor of 5 dBA is added to the evening hourly noise levels, and a factor of 10 p.BA is added to the nighttime levels, these values are then logarithmically added to determine the CNEL noise level. It should be noted that the monitor at Site A failed during the 2 a.m. hour, and the the hourly noise level from 2 a.m. on is estimated for Site A. ( Table 2 Hourly Noise Levels Hour Site A Site B Starting @ Hourly LEQ Hourly LEQ 2:00PM 55.7 58.6 3:00PM 60.5 61.8 4:00PM 58.9 59.8 5:00PM 64.1 60.9 6:00PM 61.7 60.1 7:00PM 59.0 58.8 8:00PM 63.9 67.1 9:00PM 53.1 52.3 10:00PM 44.8 47.8 11:00PM 43.8 47.4 12:00AM 54.6 57.4 1:00AM 43.4 45.9 2:00AM 45.1* 46.3 3:00AM 44.9* 46.1 4:00AM 62.5* 63.7 5:00AM 55.7* 56.9 6:00AM 58.0* 59.2 7:00AM 59.5* 60.7 8:00AM 61.1 * 62.3 9:00AM 59.6* 60.8 10:00AM 59.4* 60.6 11:00AM 61.7* 62.9 12:00PM 58.0* 59.2 1:00PM 57.7* 58.9 Total CNEL 63.7 65.1 CNEL due to Coast. 5 9. 6 56.9 CNEL w/o Coaster 61.5 64.4 Delta 2.2 0.7 * Noise levels estimated based on measurements at Site B. ( Lanikai Lane Noise Study Mestre Greve Associates Page? Near the bottom of Table 2 is the CNEL for both Sites A and B. The CNEL for Site A was 63.7 dBA, and 65.1 dBA for Site B. Since we measured the average SEL value for the Coaster operations, and we know how many and when the Coast operations occur, we can calculate the contribution of the Coaster to the CNEL noise levels. For the 24 .hours that were measured, the Coaster CNEL was 59.6 dBA for Site A, and 56.9 dBA for Site B. These values can be subtracted out from the total CNEL values to give the CNEL noise levels that are due to the Amtrak operations and the other noise sources in the area. (Please note that decibels are added and subtracted using a logarithmic scale.) The CNEL for this particular 24 hour ·' ( ( ( Lanikai Lane Noise Study Mestre Greve Associates Page8 period without the Coaster operations would be 61.5 dBA for Site A, and 64.4 dBA for Site B. In other words, the Coaster operations added 2.2 dBA to the CNEL values at Site A, and 0.7 dBA to the CNEL levels at Site B. It should be noted that during our measurement period no freight trains were observed. Also a review of the nighttime data when no person was present, would seem to indicate that no freight train operations occurred during the unattended time periods either. Freight train operations normally have a very long time duration, and none of the nighttime events had such a duration. If normal freight train operations (i.e., one freight during the day, one during the evening, and 2 during the night) were added to the mix, the CNEL noise levels at Sites A and B ~ould be about 70 CNEL. If this were the case, the Coaster operations would add less than 0.5 dBA to the total CNEL level. In community noise assessment, changes in noise levels greater than 3 dB are often identified as significant, while changes less than 1 dB will not be discernible to local residents. In the range of 1 to 3 dB, residents who are very sensitive to noise may perceive a slight change. Note that there is no scientific evidence is available to support the use of 3 dB as the significance threshold. In laboratory testing situations, humans are able to detect noise level changes of slightly less than 1 dB. In a community noise situation, however, noise exposures are over a long time period, and changes in noise levels occur over years, rather than the immediate comparison made in a laboratory situation. Therefore, the level at which changes in community noise levels become discernible is likely to be some value greater than 1 dB, and 3 dB appears to be appropriate for most people. Therefore, it does not appear that the addition of the Coaster trains could be ranked as significantly increasing the noise level. The increase in CNEL levels ranges from less than 0.5 dBA up 2.2 dBA. Are Overall Noise Levels Acceptable? The City's noise standard is 60 CNEL and this is the primary criteria by which acceptability of noise should be evaluated. Using this criteria it is clear that the noise levels at the mobile home park exceed the60 CNEL criteria. The measured CNEL values ranged from 63.7 to 65.1 dBA when apparently no freight train operations were_ operating. With freight train operations the CNEL values could e~sily be as high as 70 dBA. Therefore, the overall noise levels at the mobile home park would have to be classified as unacceptable. What are the Impacts of the Friday Coaster Operations? According to our information there are four more Coaster operations on Friday than during the rest of the week. These four operations are distributed as follows: 1 during the day period, 1 during the evening, and 2 during the night time period. The increased Friday operations cause the CNEL due to the Coaster alone to increase by 1.8 dBA over its normal weekday CNEL. If the Coaster noise levels were adjusted accordingly the Friday CNEL would be 61.4 dBA at Site A and 58. 7 at Site B. The delta increase in total noise levels due to the Friday Coaster operations would be 3.0 dBA at Site A and 1.0 dBA at Site B. The table below summarizes the results. ,I ) ( Table 3 Effect of Friday Coaster Operations CNEL w/o Coaster Friday Coaster CNEL TotalCNEL Delta due to Friday Coaster Ops. Site A 61.5 61.4 64.5 3.0 Site B 64.4 58.7 65.4 1.0 / \ Lanikai Lane Noise Study Mestre Greve Associates Page9 Finally, it should be noted that the CaliforniaDepartment of Aeronautics, by law, has defined CNEL as annual noise scale. The U.S. EPA, the California Department of Health Services, and other agencies also view the CNEL scale as an annualized noise measurement. The point is, that looking at a single day of the week is interesting, but it should not be used to make the final determination on the significance of the impact. The Coaster operations on Friday increase the CNEL noise levels by less than 3 dBA, and this generally is not considered a significant increase. However, as stated in our report, the noise levels at the mobile home park are higher than the City's criteria of 60 CNEL and this would have to be classified as unacceptable.