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HomeMy WebLinkAboutCT 90-31; AVIARA P8 28; Planning CommissionAIRPORT : ...... -= ............ • • • • • • • • • • • • • • • • • '. ......... :': ...... : • • • • • • • • -~ ~ -"oo ............ • • • • • • • • • • • • • • • • • • • • • • • -. • • • • -. ........... AVIARA PLANNING AREA 28 . ......... . • • ••• -,f ... ,:; • • ~ -! ......... : ~ : : ~ : : ~ : .... ~ • • •• City of Carlsbad c CT~ 90-31/' II: PUD 91-4 . . ... . " .. .. • • PRELIM:INARY EXTERIOR NOISE ANALYSIS FOR PLANNING AREA 28 CITY OF CARLSBAD Report # 90-267 December 6, 1990 Prepared For. Hillman Properties West, Inc. 2011 Palomar Airport Road Suite 206 Carlsbad, CA 92009 Prepared By: Vincent Mestre, P.E. :Milce Holritz MESTRE GREVE ASSOCIATES 280 Newport Center Drive Suite 230 NeWport Beach, CA 92660-7528 (714)760-0891 SUMMARY e Mestre Greve ASsociates Report # 90-267 Page 1 MINIMUM REQUIREMENTS TO MEET CITY OF CARLSBAD STANDARDS Report #90-267 December 6, 1990 EXTt:RIOR NOISE LEVELS The residences in tht;: project must comply with the City's 60 CNEL exterior noise standard. Without mitigation, exterior observers would experience a worst case traffic noise level of 69.1 CNEL at Lot 40. A number of outdoor living areas in the project will require mitigation to comply with'the 60 CNEL exterior noise standard. Those exterior areas which require mitigation are listed below in Table S 1. The data used in the noise barrier analysis are shown in the Appendix. Table Sl REQUIRED REAR YARD NOISE BARRIER HEIGHTS AND LOCATIONS TO MEET THE 60 CNEL EXTERIOR STANDARD LOT 38 39 through 42 43 through 48 49 through 53 I BARRIER HEIGHT (FT)* 7.5 8.5 8.0 7.5 * -Denotes height above top of slope With the noise barriers listed in Table S 1, the noise leyels at all exterior living areas in the project will. be reduced to below 60 CNEL. These noise barriers shall be located. at top of slope. The noise barriers must have a surface density of at least 3.5 pounds per square foot, and have no openings or cracks. The noise barriers may be a wall, berm, or a combination of the t'oiVO. The wall may be constructed of 1/4 inch plate glass, 5/8 inch plexiglass, any masonry material, or a combination of these materials. INTERIOR NOISE LEVELS The project must comply with the City of Carlsbad indoor noise standard. With the exterior noise mitigation listed above, buildings in the project will be exposed to a maximum noise level of 59.5 CNEL at the building on Lot 49. With standard construction practices in California, residential buildings achieve outdoor to indoor noise reductions of at least 20 dB assuming windows are closed. Therefore, the project will meet the 45 CNEL interior noise stand~d without building upgrades. • MECHANICAL VENTILATION REQUIREMENTS Mestre Greve Associates Report # 90-267 Page 2 The project consists exclusively of single story buildings. Therefore, with the exterior noise mitigation listed. in Table 51, all buildings in the project will be exposed to noise levels ofless than 60 CNEL Mechanical ventilation wiII not be required for Planning Area 28. • 1.0 INTRODUCTION .e PRELIMINARY EXTERIOR NOISE ANALYSIS FOR AVIARA PLANNING AREA 28 CITY 0 F CARLSB AD Mestre Greve Associates Repon # 90-267 Page 3 The purpose of this report is to show compliance of Planning Area 28 with the noise related 'Conditions of Approval' placed on the project by the City of Carlsbad. The project calls for the development of single Story homes. This repon incorporates the 60 CNEL exterior noise standard adopted by the City of Carlsbad. The project is located in the City of Carlsbad, east of Interstate 5, as shown in Exhibit 1. The project site will be impacted by traffic noise from Interstate 5. The project is not impacted uy railroad or aircraft noise. This srudy detennines the need for any mitigation measures to meet the 60 CNEL exterior noise standard, and addresses the 45 CNEL interior noise standard required by the City of Carlsbad. 2.0 NOISE CRITERIA The predominant rating scale now used in California for land-use compatibility assessment is the Community Noise Equivalent Level (CNEL). CNE.. is a 24-hour time weighted annual average noise level based on the A-weighted decibel. A-weighting is a frequency correction that correlates overall sound pressure levels with the frequency response of the human ear. Time weighting refers to the fact that noise that occurs during certain sensitive time periods is penalized for occuning at these times. The evening time period (7 PM to 10 PM) penalizes noises by 5 dB, while nighttime (10 PM to 7 AM) noises are penalized by 10 dB. These time periods and penalties were selected. to reflect peoples sensitivity to noise as a function of activity. The City of Carlsbad requires that outdoor living areas not exceed a noise level of 60 CNEL for a six-foot-tall observer located five feet mthm the property line. In addition, interior noise. levels may not exceed. 45 CNEL. The site plan for the projeCt (Exhibit 2) was prepared by P & D Technologies (''Tentative Map for Aviara Planning Area 28; October 19, 1990"). 3.0 METHODOLOGY The noise levels projected in the next section of this report were computed using the Highway Noise Model published by the Federal Highway Administration ("F1ffi' A Highway Traffic Noise Prediction Model", FRWA-RD-77-108, December 1978). The FHWA Model uses traffic volume, vehicle mix, vehicle speed, and roadway geometry to compute the "equivalent noise level". A computer code has been written which computes equivalent noise levels for each of the time periods ~sed in CNEL. Weighting these noise levels and summing them results in the CNEL for the traffic projections used. CNEL contours are found by iterating over many distances until the distance to 60, 65, and 70 CNEL contours are reached. . ~ . OCEANSIDE VISTA 76 • N ·' .. Exhibit 1 -Vicinity Map MESTRE GREVE ASSOCIATES . : ,. • Mestre Greve ASsociates Report # 90-267 Page 4 Mitigation through the design and construction of a noise barrier (wall, benn, or combination wa.J.llQenn) is the most common way of alleviating traffic noise impacts. The effect of a noise barrier is critically dependent upon the geometry between the noise source, the barrier, and the observer. A noise barrier effect occurs when the "line of sight" between the noise source and the observer is penetrated by the barrier. The greater the penetration, the greater the noise reduction. The FHW A model was also used here in computerized format to dete~e thp rCflulred barrier heights. ur~ 4.0 ROADWAY NOISE ~=r=.===-=--- The future traffic volwne for Interstate 5 was obtained from thCarlsbad Noise E~estre Greve Associates, July 7, 1990. The future average daily traffic between Poinsettia Lane and La Costa is 215,600. A vehicle speed of 60 miles per hour was utilized. Traffic distribution for each of the time periods used in the CNEL calculation is presented in Table 1. These traffic distribution estimates are based. upon traffic surveys, and are considered typical for freeways in Southern California. Table 1 TRAFFIC DISTRIBUTION. PER TIME OF DAY IN PERCENT OF ADT VEHICLE TYPE Automobile Medium Truck Heavy Truck DAY 65.83 2.92 2.10 l EVENrn'G NIGHT 17.98 0.20 0.23 9.49 0.50 0.75 Using the assumptions presented above, the future noise levels were computed. The results are reported here in Table 2 in terms of distances to the 60,6.5, and 70 CNEL contours. These represent the distances from the centerline of the roadway to the contour value shown. Note that the values given in Table 2 do not take into account the effects of intervening topography that may affect the roadway noise exposure. Topographic effects are included. in subsequent analyses to determine the actual noise exposure on the project site. In addition, these projections do not include any future vehicle noise reduction assumptions to take into account the effects of legislation requiring quieter vehicles in the furore . ". ." \~ \ ""~lt. ~ \ "" \ \ \ \ \ \\ \ .... 0: \ \ ~\ l.-", l( / \ \ \ \ ~ \ \ \\ _\ \ \ \ \ ... ~ \ \ \ \ I \ ;\ c.. ( ;', • Table 2 DISTANCE TO NOISE CONTOURS FOR FUTURE TRAFFIC CONDITIONS .: Mestre Greve Associates Report # 90-267 Page 5 FREEWAY SEGNtENT DISTANCE TO CNEL CONTOUR (FI) -70--65--60- Interstate 5 Poinsettia to La Costa 2,107 6,664 21,074 The results in Table 3 and the site plan (Exhibit 2) indicate that a number of exterior living areas in the project will be exposed to traffic noise levels in excess of 60 CNEL. Exterior observers facing Interstate 5 will experience a worst case traffic noise level of 69.1 CNEL at Loe 40. 5.0 EXTERIOR NOISE MITIGATION For the exterior living areas which are exposed to noise levels greater than 60 CNEL, some form of noise mitigation is required. An effective method of reducing the traffic noise levels to acceptable levels is with a noise bamer. Representative cross-sections along the roadway (see Appendix for analysis data) were analyzed. utilizing the FHW A Model to determine the necessary noise barrier locations and heights. The results of the analysis indicate that in order to meet the 60 CNEL exterior noise standard, noise bamers are required. for a number of exterior living areas facing Interstate 5. Required noise barrier locations and heights to meet the 60 CNEL exterior noise standard are listed in Table 3, and shown in Exhibit 3. The noise barriers shall be located. at top of slope as shown in Exhibit 3. Table 3 REQUIRED REAR YARD NOISE BARRIER HEIGHTS AND LOCATIONS TO MEET THE 60 CNEL EXTERIOR STANDARD LOT 38 39 through 42 43 through 48 49 through 53 * -Denotes height above top of slope BARRIER HEIGHT (FI)* 7.5 . 8.5 8.0 7.5 .' c.n t:: -....., 0 s... .-c::: ..... -", c::: ....., ~ C .z 0 c::: ~ ~ CI') ~ :.... ~ ~ ~ .-~ :.... Z ~ :.... ..... c::: U ... \ ,~ '\, 0 \\ \0 Y ~ ~ I CJ jt ..... ~ . -~ ,CJ .- ;~ ,... -0 X ~ ~ i ! I .. 1 ,) r ["" t It / I ; { UJ I I '~ / Z I 0 t \~ -.... :,.~ < (.,) \~ 0 ,,~lt. ..J ~ a: '.:' , \ w -~~ \. 0:: 0:: \ < m \ '- ;\ ( -" J ... 1 l .. ~ '\ • • ... , . t.: • • • (, • • • • • • • • • • • Mestre Greve Associates Report # 90-267 Page 6 The noise barriers may be a walL berm. or combination wal1/berm. The noise barriers are required to have a surface density of at least 3.5 pounds per square foot. and have no openings or cracks. They may be constructed of wood studs with stucco exterior, 1/4 inch plate glass, 5/8 inch plexiglass, any masonry material, or a combination of these materials. 6.0 INTERIOR NOISE MITIGATION The project must comply with the City of Carlsbad indoor noise standard. The project consists exclusively of single Story buildings. With the exterior noise mitigation described in section 5.0, building faces in the project will be exposed to a maximum noise level of 59.5 CNEL at the building on Lot 49, therefore requiring at least 14.5 dB outdoor to indoor noise reduction to meet the interior standard. With standard construction practices in California, residential buildings achieve outdoor to indoor noise reductions of at least 20 dB assuming windows are closed. Therefore, all buildings in the project will meet the 45 CNEL interior noise standard without building up grades. 7.0 MECHANICAL VENTILATION REQUIREMENTS Since the noise attenuation of a building falls to abOut 15 dB with windows open, any buildings exposed to noise levels greater than 60 CNEL would meet the 45 CNEL interior noise standard only with windows closed. The project consists exclusively of single story buildings. Therefore, with the exterior noise mitigation described in section 5.0, all building faces in the project will be exposed to noise levels of less than 60 CNEL. Mechanical ventilation win noe be reguired for Planning Area 28. '. • lot 38 39 40 41 43 45 47 49 51 53 55 57 • APPENDIX Mestre Greve Associntes Report # 90-267 Page 7 DATA USED TO DESIGN NOISE BARRIERS ALONG INTERSTATE S Road Distance BaSe Of Dist. To Pad Observer Elevation To Wall Wall Observer Elevation Height 21.5 1500 75 1555 75 5 21.5 1590 75 15S5 75 5 , 21.5 1500 74 1505 74 5 21.5 1720 70.5 1725 70.5 5 21.5 1880 53.9 1885 53.9 5 21.5 2020 41.3 2025 41.3 5 21.5 2140 38.5 2145 38.5 5 21.5 2260 35.7 2255 36.7 5 21.5 2390 40 2395 40 5 21.5 2S2O 52.9 2525 52.9 5 21.5 / 2750 54.1 2755 54.1 5 21.5 2770 54.1 2950 59.3 5 5· "" ",'\ . \ '. \ \ \ \ \ ~ AflPORT ............. ." . • • • • • • · .. • • ----------------------------------~:--------~1~----------• • • • . , . • • • • • • • • :u.u,: : : ......... :: .. . · ,...... : •• • •• • • • · ._.; • • • • • • • • ........... City of ,CaMsud ..