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Home My WebLink AboutCUP 255; Villas de Carlsbad; Conditional Use Permit (CUP) (2)NOISE STUDY AND EVALUATION FOR VILLAS DE CARLSBAD Prepared For: Income Property Group 1060 Eighth Avenue, Suite 405 San Diego, California 92101 Prepared By: RBR & Associates, Inc. 233 "A" Street. Suite 904 San Diego, California 92101 RBR job\i!^to74 HscBlved APR 05 139) CITY OF CARLSBAD DEVELOP^ PROC, SERV. DIV TABLE OF CONTENTS I. INTRODUCTION II. METHODOLOGY III. ANALYSIS OF CONDITIONS IV. CONDITIONS OF DEVELOPMENT AND MITIGATION EXTERIOR V. CONDITIONS OF DEVELOPMENT AIJD MITIGATION INTERIOR VI. CONCLUSIONS VII. REFERENCES FIGURES 1. Project Vicinity 2. Preliminary Site Plan, Villas de Carlsbad 3. Current (1983) Noise Level Contours (Ldn) 4. Future (2005) Noise Level Contours (Ldn) TABLES Noise Analysis, Current Conditions, Southbound Lanes 1-5 Noise Analysis, Current Conditions, Northbound Lanes 1-5 Noise Analysis, Future Conditions, Southbound Lanes 1-5 Noise Analysis, Future Conditions, Northbound Lanes 1-5 11 ATTACHMENTS 1. The FHWA Noise Prediction Model 2. Noise Factors 3. Noise Element, San Diego County General Plan Policy 4b 111 I. INTRODUCTION The proposed Villas de Carlsbad project would be located immediately west of Interstate 5 in the City of Carlsbad and approximately one-half mile south of Buena Vista Lagoon (see Figure 1). Laguna Drive forms the southern boundary of the property and Knowles Avenue forms the northern boundary of the property. Both of these streets dead-end at the western right-of-way of Interstate 5. This continuing care for the elderly project consists of three three-story buildings. The 91 residential units are composed of 34 one-bedroom and 57 two-bedroom units on 4.63 acres of land. The proposed locations of the three buildings on the property are shown in Figure 2. The traffic flow along Interstate 5 would be the major noise generator to the project site. Traffic volumes on the freeway will increase about 19% over existing conditions. The most recent traffic counts conducted by Caltrans (1983) showed an average daily trip volume of 101,000. Caltrans estimates that the average daily trip volume will increase to 120,000 in the year 2005 (Stryker, 1984). Current and future noise level contours were determined in order to identify and mitigate these noise impacts. To ensure accurate future noise level forecasts, validation of the Federal Highway Administration (FH^JA) Noise Prediction Model at this site was deemed necessary. J"=2000' \ 1071 RBR and Associates PROJECT VICINITY (Source: Aerial Graphics, 1982) Figure 7 1074 KA/QWi,£S... -L^aon j» ^ in H -T-T •—'.j— r-*^ % RBR and Associates PRELIMINARY SITE MAP VILLAS DE CARLSBAD Figure 2 Several ten-minute traffic counts were conducted during peak hours on Interstate 5. Simultaneous noise level measurements were recorded at various locations on the property. The locations of the noise monitoring positions were betv^een 50 and 100 feet from the property's eastern boundary. Traffic speeds were assumed to be constant at 55 miles per hour. The actual traffic counts obtained and the existing site parameters were used in the FHVJA Noise Prediction Model to determine computational decibel levels. These decibel levels were then compared to the actual measurements recorded earlier at the designated noise monitoring positions. The computa- tional decibel levels were found to be 1.7 to 2.5 decibels higher than the actual recorded noise level readings; thus the noise levels predicted by the FHV7A Model are conservative. This difference is within statistically acceptable standard deviation units. The validation of the FH\7A Noise Prediction Model permitted an accurate estimate of current and future noise levels using Caltrans' most recent traffic counts and future projections for the section of 1-5 adjacent to the proposed Villas de Carlsbad project. II. METHODOLOGY The FHV7A Noise Prediction Model (FHWA-RD-77-108, 1978) was used in this study for all noise calculations. The FHV7A Model uses the A-weighted scale of noise measurement, as that most closely approximating human perception of loudness. The Model calculations begin at reference noise levels which can then be adjusted for traffic speed, traffic volume and vehicle type, distance between noise source and receiver, length of roadway within direct sight of the receiver, and any barriers between the noise source and observer that affect noise transmittance. These factors are discussed in detail in Attachment 1. Current traffic counts of 101,000 ADT and future traffic projections obtained form Caltrans were used in order to calculate noise levels generated by vehicles utilizing Inter- state 5. The traffic flows were separated into the average number of vehicles per hour during the daytime hours (7 AM to 10 PM) and during the nighttime hours (10 PM to 7 AM) as shown in the foot of Tables 1-4. The distance separating a noise source from its point of interception is an important factor when determining noise levels. Interstate 5 was split into two separate roadways (northbound and southbound) for the purposes of this study. This permits a more accurate assessment of the noise levels generated by vehicular traffic. TABLE 1 Noise Analysis Villas de Carlsbad Current Conditions (1983) Southbound Lanes 1-5 CARS MEDIUM TRUCKS HEAVY TRUCKS VPH - Day 2683 108 138 VPH - Night 668 27 34 Speed (km/hr) 88.5 88.5 88.5 Distance (meters) 21 17 17 Reference Levels 71.8 82.4 86.4 Flow Adjust - Day 26.6 12.6 13.7 Flow Adjust - Night 20.5 6.6 7.6 Distance Adjust -1.5 -0.5 -0.5 Constant -25 -25 -25 dBA - Day 71.9 69.5 74.6 dBA - Night 65.8 63 .5 68.5 Leq Day [77.3] Leq Night Ldn at 50' [71.2] Leq Night Ldn at 50' 79.2 Computations of Vehicles Per Hour (101,000 ADT Counted) VPH Day = (0.87) (ADT) X 1^ = 2929 15 2 CARS MEDIUM HEAVY (91.6%) TRUCKS (3.7%) TRUCKS (4.7%) 2683 108 138 The 15 hours between 7 AM and 10 PM are designated "day' VPH Night = (0.13) (ADT) X _1 = 729 9 2 CARS MEDIUM (91.6%) TRUCKS (3.7%) HEAVY TRUCKS (4.7%) 668 27 34 The 9 hours between 10 PM and 7 AM are designated "night" TABLE 2 Noise Analysis Villas de Carlsbad Current Conditions (1983) Northbound Lanes 1-5 CARS MEDIUM TRUCKS HEAVY TRUCKS VPH - Day 2683 108 138 VPH - Night 668 27 34 Speed (km/hr) 88.5 88.5 88.5 Distance (meters) 32 35 35 Reference Levels 71.8 82.4 86.4 Flow Adjust - Day 26 .6 12.6 13 .7 Flow Adjust - Night 20.5 6.6 7.6 Distance Adjust -3.3 -3.7 -3.7 Constant -25 -25 -25 dBA - Day 70.1 66.3 71.4 dBA - Night 64.0 60.3 65.3 Leq Day [74.5] Leq Night [68.4] Ldn at 50' 76.4 Computations of Vehicles Per Hour (101,000 ADT Counted) VPH Day = (0.87)(ADT) X 1 = 2929 15 2 CARS MEDIUM HEAVY (91 .6%) TRUCKS (3.7%) TRUCKS (4.7%) 2683 108 138 The 15 hours between 7 AM and 10 PM are designated "day". VPH Night = (0.13) (ADT) X 1^ = 729 9 2 CARS MEDIUM (91.6%) TRUCKS (3.7%) HEAVY TRUCKS (4.7%) 668 27 34 The 9 hours between 10 PM and 7 AM are designated "night". TABLE 3 Noise Analysis Villas de Carlsbad Future Conditions (2005) Southbound Lanes 1-5 CARS MEDIUM TRUCKS HEAVY TRUCKS VPH - Day 3188 129 163 VPH - Night 794 32 41 Speed (km/hr) 88 .5 88.5 88 .5 Distance (meters) 21 17 17 Reference Levels 71 .8 82.4 86 .4 Flow Adjust - Day 27 .3 13 .4 14 .4 Flow Adjust - Night 21 .3 7.3 8 .4 Distance Adjust -1 .5 -0.5 -0 .5 Constant -25 -25 -25 dBA - Day 72 .6 70.3 75 .3 dBA - Night 66 .6 64.2 69 .3 Leq Day [78.0] Leq Night [72.0] Ldn at 50' 79 .9 Computations of Vehicles Per Hour (120,000 ADT Projected) VPH Day = (0.87)(ADT) X 1 = 3480 15 2 CARS MEDIUM HEAVY (91.6%) TRUCKS (3.7%) TRUCKS (4.7%) 3188 129 163 The 15 hours between 7 AM and 10 PM are designated "day" • VPII night = (0.13) (ADT) X 1 = 867 9 2 CARS MEDIUM HEAVY (91.6%) TRUCKS (3.7%) TRUCKS (4.7%) 794 32 41 The 9 hours between 10 PM and 7 AM are designated "night • -.J TABLE 4 Noise Analysis Villas de Carlsbad Future Conditions (2005) Northbound Lanes 1-5 CARS MEDIUM TRUCKS HEAVY TRUCKS VPH - Day 3188 129 163 VPH - Night 794 32 41 Speed (km/hr) 88.5 88.5 88.5 Distance (meters) 32 35 35 Reference Levels 71 .8 82.4 86.4 Flow Adjust - Day 27.3 13 .4 14.4 Flow Adjust - Night 21.3 7.3 8.4 Distance Adjust -3.3 -3.7 -3.7 Constant -25 -25 -25 dBA - Day 70.8 67 .1 72.1 dBA - Night 64.8 61.0 66 .1 Leq Day [75.2] Leq Night [69.2] Ldn at 50' 77.1 Computations of Vehicles Per Hour (120,000 ADT Projected) VPH Day = (0.87)(ADT) X 1 = 3480 15 2 CARS MEDIUM HEAVY (91.6%) TRUCKS (3.7%) TRUCKS (4.7%) 3188 129 163 The 15 hours between 7 AM and 10 PM are designated "day" VPH Night = (0.13)(ADT) X 1 = 867 9 2 CARS MEDIUM HEAVY (91.6%) TRUCKS (3.7%) TRUCKS (4.7%) 794 32 41 The 9 hours between 10 PM and 7 AM are designated "night" Factors and assumptions used in the application of the FHVJA Model were: 1) Traffic volumes were split equally between the north- bound and southbound lanes; 2) Rate of vehicular speed would be constant at 55 mph; 3) Passenger cars would account for approximately 91.6 percent of the traffic flow, medium trucks 3.7 per- cent and heavy trucks 4.7 percent of the total traffic flow; 4) Direct line-of-sight to the freeway possible from all areas of the site; 5) The site was considered acoustically hard; and 6) Width of the noise pathlength between noise source and receiver was 180 degrees. Once the equivalent continuous sound levels (Leqs) were deter- mined, their values were transformed into day/night average noise levels (Ldn). This scale weights the nighttime Leq with an additional 10 decibels due to increased perception and annoyance associated v/ith noise generated between the hours of 10 PM and 7 AI-I. A summary of the existing conditions can be found in Tables 1 and 2. Anticipated future conditions are summarized in Tables 3 and 4. The results are discussed below in Analysis of Conditions. III. ANALYSIS OF CONDITIONS The following section discusses noise levels as theoretical projections on the vacant site. This is done in order to identify those buildings which lie within potentially signifi- cant noise contours. Conditions associated with construction of the project and specific mitigation measures are discussed in the next two sections. The current hourly equivalent sound levels 50 feet from the center of the traffic lane nearest the project will be ap- proximately 80 decibels (Ldn). The 75 decibel (Ldn) contour will lie approximately 120 feet from the centerline of the nearest traffic lane and the 70 decibel (Ldn) contour will lie approximately 280 feet from the centerline of the traffic lane nearest the project. These contours are illustrated in Figure 3. These are general estimates of distances to the noise contours, assuming only straight-line attenuation. The site is essentially level with the freeway. The future hourly equivalent sound levels 50 feet from the center of the traffic lane nearest the project will be ap- proximately 81 decibels. The 75 decibel contour will be located approximately 155 feet from the centerline of the nearest traffic lane and the 70 decibel contour will lie approximately 320 feet from the centerline of the traffic lane nearest the project. These contours are shown in Figure 4. The proposed units which would be closest to Interstate 5 % K%OWLES ^m£~ 1 1074 Centerline of neorest traffic -lane RBR and Associates VILLAS DE CARLSBAD 1983 NOISE LEVEL CONTOURS (Ldn) Figure 3 1074 mi x: ^ . t Centerline of nearest traffic lane -i^Mtn • 34 o—5 ' 7^1 ff v.-fiaja^t/-—<• u RBR and Associates VILLAS DE CARLSBAD 2005 NOISELEVEL CONTOURS (Ldn) Figure 4 would be a minimum of 100 feet from the centerline of the nearest traffic lane and located in a noise contour of 76 decibels. Recreation areas for the proposed project would be located within 15 feet of the property line adjacent to Inter- state 5. The noise levels at this location will be approxi- mately 77 decibels. IV. CONDITIONS OF DEVELOPMENT AND MITIGATION — EXTERIOR All of the units within this proposed project v/hich are directly adjacent to Interstate 5 would lie within current noise contours of 70 to 75 decibels. Noise levels at these same locations are anticipated to rise by 1 to 2 decibels by the year 2005. Most units located on the far side of the buildings away from the freeway v/ill be sufficiently shielded such that exterior noise levels will be below 70 decibels. Exterior use areas are shown in Figure 3 and v/ould lie within a current noise contour of 75-77 decibels. The City of Carlsbad has not as yet adopted a set of its own noise standards (Krem, 1984). Carlsbad essentially follows the guidelines set forth in the Noise Element of the San Diego County General Plan. Section 4b of the County Noise Element states that when noise sensitive areas (i.e., bedrooms, out- door use areas) in a new development will be subjected to noise levels greater than 60 decibels, one of two findings must be made prior to project approval. Specifically, modifi- cations to the development have been or will be made which reduce the exterior noise level below 60 decibels or, if it is infeasible to reduce exterior noise levels to 60 decibels, then modifications to the development have been or will be made which reduce interior noise to 45 decibels or below. The use of site planning and buffer areas to reduce noise impacts between noise sources and sensitive receivers should be considered for this project. The construction of a noise wall 6 to 8 feet high between the freeway and the project would aid in reducing noise levels for first-story units, but would not mitigate noise levels below a level of significance. Other means that could be employed to reduce noise impacts are as follows: o Reverse the orientation of buildings B and C such that the buildings themselves will act as a noise barrier and place exterior use areas within these noise shadows; o Site non-sensitive areas (parking) close to the freev/ay and set buildings back from the freeway as far as possible. V. CONDITIONS OF DEVELOPMENT AND MITIGATION — INTERIOR The exterior environment for units located adjacent to Inter- state 5 (see Figure 3) would be subject to current noise levels of 60 decibles or greater. Title 25, Section 1092, Article 4 of the California Adminis- trative Code, a standard which the City of Carlsbad must enforce at the Villas de Carlsbad site, regulates maximum allowable interior noise levels for new construction projects. This noise standard requires new multiple family dwelling units that are constructed within a noise exposure of 60 decibels CNEL or greater to be designed such that interior noise levels do not exceed 45 decibels CNEL with windows closed. If exterior noise levels cannot be reduced to accept- able levels, specific design and construction techniques must be utilized to assure the 45 decibel CNEL interior standard is met. Protection of the receiver principally involves installing noise-reducing materials and equipment into a new building, such as wall and ceiling insulation, double-glazed or extra thick windows, nondirect vents and solid-core doors in order to reduce the intrusion of outside noise into a building. It is often preferable to reduce exterior noise at a new dwelling or other building. If this is not possible, however, then the use of appropriate insulation and other materials in building construction can effectively mitigate a potential noise im- pact. This method of noise attenuation is appropriate in areas where exterior exposures cannot feasibly be mitigated. VI. CONCLUSION Mitigation of exterior noise levels below a level of signifi- cance for all portions of the site are not feasible. Some reduction in noise levels can be achieved through the use of site planning, a larger buffer zone between the freeway and the proposed units and the construction of a noise vi/all along the eastern property boundary. A noise wall 6 to 8 feet in height would reduce noise levels only for the first story units of the project. Mitigation of anticipated interior noise level impacts can be achieved through the use of acoustical treatments such as mechanical ventilation, double-glazed windows and wall and ceiling insulation. An analysis of the reduction of interior noise levels provided by acoustical construction for specific units within each building may be required. Detailed architectural drawings showing room sizes, locations of noise sensitive rooms, window sizes and construction materials would be needed to perform a more exact acoustical analysis. VII. REFERENCES California Administrative Code, Title 25, Chapter 1, Sub- chapter 1, Article 4, Noise Insulation Standards (Section T25-1092). Harris, Cyril M., Ph.D., (editor), 1979, Handbook of Noise Control, Second Edition. Lipscomb, David M., Ph.D. and Taylor, Arthur C., Jr., Ph.D., (eds.), 1978, Noise Control Handbook of Principles and Practices. May, Daryl N., Ph.D., 1978, Handbook of Noise Assessment. National Association of Homebuilders, 1978, Acoustical Manual. U.S. Department of Transportation, Federal Highway Administra- tion, 1976, Highway Noise, a reprint of: The Audible Landscape: A Manual for Highway Noise and Land Use (1974). U.S. Department of Transportation, Federal Highway Administra- tion, 1978, FHWA Highway Traffic Noise Prediction Model, FHWA RD-77-108. ATTACHMENT 1 THE FHV/A MODEL A. Reference Mean Energy Emission Level Each representative type of vehicle, while moving at a con- stant rate of speed past a particular point, produces a measurable level of sound. This sound level is termed the reference energy mean emission level, L^„ Noise levels increase with an increase in vehicle's weight or speed. For example, one car (i.e., passenger vehicle or light truck having 2 axles and 4 wheels) passing by at a distance of 15 meters and at a speed of 35 miles per hour (56.3 kilometers per hour) will produce a single event noise level measuring approximately 64.3 decibels. A medium truck (i.e., 2 axles, 6 wheels, gross weight between 4,500 kilograms and 12,000 kilo- grams), under identical conditions will produce a single event noise level of 76 decibels; a heavy truck (3 or more axles, gross weight greater than 12,000 kilograms) under identical conditions will produce a single event noise level of 82 decibels. B. Traffic Flow Adjustment As the number of vehicles passing a particular point in- creases, noise levels are no longer a series of single events, but rather become cumulative. That is, there is a sustained level of noise punctuated with brief periods of noticeable increase or decrease. The reference energy mean emission level must be adjusted for traffic flow rates. By making the time period under consideration equal to one hour, the refer- ence energy mean emission level (a peak value) is converted to an hourly equivalent sound level. C. Distance Adjustment ^rtien the distance between the roadway under study and the observer is not exactly 15 meters, an adjustment for noise level rates is necessary. As an observer moves away from a noise source, sound level decreases, although not in a linear fashion. This lessening of sound levels with increased dis- tance from the noise source is referred to as the drop-off rate and is expressed in terms of decibels per doubling of distance. VJhen the ground between the observer and the road- way is acoustically hard (i.e., covered by pavement or other non-absorptive surface), the site is considered to be sound reflective. The drop-off rate for this situation is three decibels per doubling of distance. IThen the intervening ground is covered by grass or other forms of vegetation, the site is absorptive. The drop-off rate under this condition is 4.5 decibels per doubling of distance. ^' Finite Length Roadway Adjustment In many cases, the roadway is not infinitely long in both directions relative to the observer, as is assumed in the FH17A Model. Freeway ramps, buildings and hillsides can decrease the area of a road that is visible to the observer. It then becomes necessary to adjust the reference energy level to account for the energy contributions of the visible path- length of roadv/ay. The computational problems associated with finite length roadways is complicated by the fact that ground effects must be taken into consideration. ATTACHMENT 2 NOISE FACTORS Noise, defined as unwanted or excessive sound, is now broadly recognized as a form of environmental degradation. Urban noise is a composite of undesirable sound created by transpor- tation, industrial and miscellaneous sources. The most far- reaching noise source today stems from transportation opera- tions with highway vehicular noise clearly the most pervasive transportation noise source. Although many of the findings related to noise lend themselves to a variety of interpretations, there is general scientific agreement on a number of factors: 1. Noise of sufficient intensity has caused irreversible hearing damage. 2. Noises have produced physiological changes in humans and animals that in many cases have not resulted in adaptation. 3. The effects of noise are cumulative, and even rela- tively unobtrusive noise over a lifetime can result in physical deterioration. 4. Noise can interfere with speech and other communica- tion. 5. Noise can be a major source of annoyance by disturb- ing sleep, rest and relaxation. 6. Psychological stress can result from noise. Three factors of noise which affect human response are inten- sity (i.e. loudness), frequency and time. Any scheme for predicting the effects that noise might have on human response (i.e. the impact of noise), must in some way account for each of the three parameters. The first factor is adequately accounted for in the case of traffic noise by measuring or calculating the noise in terms of sound levels. Sound levels are usually measured and expressed in decibels (dB). The "frequency" or "pitch" of a sound refers to the complete pressure fluctuation per second in the sound. Most sounds we hear do not consist of a single frequency but of a broad band of frequencies differing in relative level. The quantitative expression of the frequency and level content of sound is its spectrum. Many rating methods have been devised to permit comparison of sound having quite different spectra. The measurement scale that has been found to approximate a human's perception of sound is the "A" scale. Therefore, the descrip- tor of loudness as perceived by people is expressed dBA. Although the dBA measurement may adequately describe environ- mental noise at any instant in time, the fact is that noise levels vary continuously. Most environmental noise includes a conglomeration of background noise in which no particular source is identifiable. These sources may be relatively con- stant or vary slowly from hour to hour. This is caused by the change of natural forces or of human activity as it follows its daily cycle. Superimposed on this background noise is a succession of identifiable noisy events of brief duration. These may include nearby activities or single vehicle pas- sages, aircraft flyovers, etc., which cause the environmental noise level to vary from instant to instant. These factors may be accounted for by use of various noise measurement methodologies. The day-night average noise level scale, L^^^^^ ^as used in this analysis. Three reasons for the choice of this noise scale are as follows: 1. The scale includes corrective factors for both event duration and the number of events in a 24-hour period. 2. The scale can be used for the analysis of noise from diverse sources including vehicular traffic, aircraft, rail operations, and stationary sources. 3. The scale is used by the San Diego Association of Governments (SANDAG), the Environmental Protection Agency (EPA), Caltrans and the County of San Diego. •'^dn noise rating scale is a measure of the cumulative noise exposure in a community, with weighted factors being applied to noise occurring during nighttime periods. The L^^j^ scale is roughly the same as the Community Noise Equivalent Level (CNEL). Transportation noise has been identified as the most signifi- cant source of projected noise impacts. A better understand- ing of traffic related noise is possible when various factors which affect transportation noise levels are known. These include: 1. Given the same roadway and traffic conditions, trucks generate more noise than automobiles. 2. Increases in travel speeds increase the noise level for automobiles. 3. Sound levels decrease as one moves away from the noise source. 4. The noise of diesel trucks increases significantly with gradient; however, gradient has little influence on the noise of automobiles. 5. Noise level for trucks is inversely proportionate to their speeds. 6. Noise level for trucks increases significantly in stop-and-go traffic. 7. Shielding by roadside barriers attenuates sound. 8. Other factors that influence sound are median land- scaping and type of road surface. Noise Measurement All noise measurements were made with a Bruel and Kjaer, type 2205 precision sound level meter. The Bruel and Kjaer 2205 conforms with AtJSI sl.4-1971 Type 1 for precision sound level meters. It is equipped with a piezoelectric microphone Type 4148 with a frequency response from 30Hz to 10,000Hz and dynamic range from 30dB-140dB. The instrument was calibrated before and after application with the Bruel and Kjaer type 4230 sound level calibrator. The A-weighting scale was used for measurement and climatological conditions were noted. ATTACHMENT 3 POLICY kb Because exterior community noise equivalent levels (CNEL) above 55 to 60 decibels and/or interior CNEL levels above ^5 decibels may have an adverse effect on public health and welfare, it is the policy of the County of San Oiego that: 1. Whenever possible, development in San Diego County should be planned and constructed so that noise sensitive areas are not subject to noise in excess of CNEL equal to 55 decibels. 2. Whenever it appears that new development will result in any (existing or future) noise sensitive area being subjected to noise levels of CNEL equal to 60 decibels or greater, an acoustical study should be requi red. 3- If the acoustical study shows that noise levels at any noise sensi- tive area will exceed CNEL equal to 60 decibels, the development should not be approved unless the following findings are made: A. Modifications to the development have been or will be made which reduce the exterior noise level below CNEL equal to 60 decibels; or 8. If with current noise abatement technology it is infeasible to reduce exterior CNEL to 60 decibels, then modifications to the development have been or will be made which reduce interior noise below CNEL equal to '•5 decibels. Particular attention shall Jje given to noise sensitive interior spaces such as bedrooms. And, C. If finding "8" above is made, a further finding is made that there are specifically identified overriding social or economic considerations which warrant approval of the development without modification as described in "A" above. k. If the acoustical study shows that noise levels at any noise sensitive area will exceed CNEL equal to 75 decibels» the development should not be approved. Oefinitions (applicable to paragraph I through 4 of Policy kb) "Development" means any physical development including but not limited to residences, commercial, or industrial facilities, rdads, civic buildings, hospitals, schools, airports, or similar facilities. Vll I-I8 "Noise Sensitive Area" means the building site of any residence, hospital, school, library, or similar facility where quiet is an important attribute of the environment. Exempt ion 1. For the rooms in "Noise Sensitive Areas", which are usually occupied only a part of the day (schools, libraries, or similar), the interior one-hour average sound level, due to noise outside, should not exceed 50 decibels. 2. For County road construction projects, the exterior noise level due to vehicular traffic impacting a noise sensitive area should not exceed the Following values: A. Federally funded projects shall comply with applicable Federal Highway Administration Standards. 3. Other projects - CNEL » 60 dBA, except if the existing or pro- jected noise level without the project is 58 dBA or greater a 3 d8A increase will be allowed, up to the maximum permitted by Federal Highway Administration Standards. Action Program ^bl. Recommend programs to soundproof buildings or redevelop areas where it is impossible to reduce existing source noise to acceptable I eve Is. ,^ Action Program kbZ. Study the feasibility of extending the application of Section 1092, California Administrative Code dealing with noise insulation standards to single-family dwellings, and incorporating higher standards for reduction of exterior noise intrusion into structures. Action Program kb3- Require present and projected noise level data to be included in Environmental Impact Reports. Designs to mitigate adverse noise impacts shall also be used. VI I I-I5