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Home My WebLink AboutPIP 97-06; Carlsbad Crest Corporate Center; Planned Industrial Permit (PIP) (21)ACOUSTECH CONSULTANTS REPOm NO. 0597-P9 Acoustical Analysis Report for Two Proposed Buildings on Lots 41 Airport Business Center, Carlsbad July 7, 1997 Prepared For: Mr. Larry Woodward C.A.C.Associates, L.L.C, 9820 Willow Creek Road Suite 400 San Diego, California 92131 For Submittal To: City of Carlsbad Planning Department 2075 Las Palms Drive Carlsbad, California 92009-1576 Prepared By: Gary W. Hicks Acoustech Consultants Certified Acoustical Consultant - San Diego County 5 Report Number 059749 July 7, E97 EXECUTIVE SUMMARY An acoustical analysis was performed for two industrial buildings adjacent to Palomar Airport. The exterior noise levels are 75 dB CNEL at building 2 and 70 dB CNEL at building 1. Windows and roofs are critical noise transmission elements. Building 1 meets the 50 dB CNEL interior noise requirement with the proposed construction. No special building elements are required. Building 2, 1st floor meets the interior noise limit with the proposed construction. Building 2, 2nd floor, requires up-graded construction. The roof area of the mezzanine office space needs to have an added layer of gypsum board to reduce sound transmission from above. Both buildings require mechanical ventilation or air-conditioning providing at least 2 fresh air changes per hour. 10731 Old Saybrook Drive, San Diego, California 921 29 Telephone & Fax (619) 672-2043 ~ ~ ~~ ~ Report Number 0597-P9 July 7, 1997 1 1.0 BACKGROUND 1.1 Purpose This report provides an evaluation of the interior noise levels expected for two proposed industrial buildings to.be located on Lot 41 adjacent to McClellan- Palomar Airport in the Airport Business Center 1.2 Requirements SANDAG has reviewed proposals for industrial buildings on lot 41 and determined that the lots are within the Carlsbad Airport Center Specific Plan. The projected 75 dBA Community Noise Equivalent Level (CNEL) noise contour for McClellan-Palomar Airport overlaps a portion of this lot. Building 2 proposed for construction within the 75 dBA CNEL contour should be attenuated to an interior noise level of 50 dBA CNEL. Building 1 does not fall within the 75 dBA CNEL contour; however, for completeness, the interior noise levels this building will also be evaluated. 1.3 Mitigation Interior noise levels will be estimated based upon the proposed construction. If the 50 dBA CNEL limit is not achievable with standard construction, construction improvements will be recommended which will reduce interior noise levels no higher than 50 dBA CNEL. 2.0 DESCRIPTION OF SITE AND BUILDINGS 2.1 Site Location The proposed site is adjacent to the airport in the business center, north of Camino Via Roble and east of Palomar Oaks Way. Figure 2.1 illustrates the site plan and CNEL contours. 2.2 Existing Site Noise Conditions SANDAG has determined that airport traffic will result in a Community Noise Equivalent Level (CNEL) of between 70 and 75 dBA. A worst-case CNEL of 75 dBA will be assumed in evaluating Building 2; an average CNEL of 70 dBA will be assumed in evaluating Building 1. 10731 Old Saybrook Drive, San Diego, California 92129 Telephone & Fax (619) 672-2043 Report Number 0597-P9 2 I t“ Palomqr Airport _j July 7, 1997 Figure 2-1 Site Plan 10731 Old Saybrook Drive, San Diego, California 92129 Telephone 8, Fax (619) 672-2043 ” c Report Number 0597-F9 3 July 7, 1997 2.3 Building Characteristics Building 1 has a square footage of 33,700 square feet while Building 2 is approximately 33,000 square feet. Both buildings consist of tilt-up concrete walls and an office area with glass front. Key noise transmission features include the roof, a roll-up access door, and windows. Table 1 below provides the building elements and relevant areas. Table 1 Areas Sc STC's of Building Elements (Before Upgrades) Building Element Estimated STC Areas, ft2 B1-1st B1-2nd B2-1st B2-2nd (1) Roll-up Door (standard) 15 468 0 578 0 Access Door (standard) 26 138 0 90 0 (2) Fixed Glass 27 1810 1614 976 1841 (3) Roof 31 18700 7500 10061 6600 Concrete wall (4"-5") 46 9433 2034 9433 1935 (1) Est, 24 ga. sheet metal, minimal gasket (2) Fixed 1/4" thick single pane (3) steel bar trusses; rooftop 518" plywood with paper and waterproof coating The large area of the roof results in substantial noise transmission from aircraft noise. 3.0 INTERIOR NOISE ESTIMATION METHODOLOGY 3.1 Prediction Technique To estimate the interior noise in the buildings, we assume that the roof and exterior walls may receive up to 75 dBA CNEL (building 2) and up to 70 dBA CNEL (building 1). The interior noise (Lin) can be determined by: where Lout = the octave band exterior noise levels (total 75 dBA CNEL) TL = the octave band transmission loss of the individual building elements S = the surface area of the various building elements A = the room absorption in Sabins In practice, the composite transmission loss (TLJ for the building exterior 10731 Old Saybrook Drive, San Diego, California 92129 Telephone & Fax (619) 672-2043 Report Number 0597-F9 July 7, 1!397 4 elements is calculated based upon the individual transmission loss and areas. To calculate the composite transmission loss of a multi-element wall, the following equations are employed: TL, = 10 log,, (1hJ where TL, is the transmission loss of the multi-element wall or roof in dB. zc is the composite wall or roof transmission cgefficient. S,,S2, -ST are the areas of individual wall or roof elements. z,, z2, -- zn are the sound transmission coefficients of the individual elements. ST = total wall or roof area; C S, +S2 --- Sn The terms z,, z2, -- zn can be calculated from the element STC values or from octave-band single element transmission loss values by solving the equation: = l/antiloglo [STC/lO] OR, = t l/antiloglo PUlO] The details of the wall composite transmission loss calculations must be performed for exterior partitions which include elements other than bare stucco. 3.2 Noise Spectrum and Transmission Loss The exterior noise due to aircraft must reflect both nearby and distant aircraft. The 75 & 70 dBA CNEL is estimated to consist of the following octave band levels: - 125 - 250 - 500 1000 - 2000 4ooo dBA Linear Suectrum 80 78 70 66 64 62 75 75 73 65 61 59 57 70 - 10731 Old Saybrook Drive, San Diego, California 92129 Telephone 81 Fax (619) 672-2043 Report Number 0597-p9 July 7, 1997 5 The transmission loss of standard and upgraded building elements is as follows: Table 2 Transmission Loss of Building Elements - Item ( 1) Roll-up door (std) (2) Roll-up door (special) Access door (3) Fixed window, 3/16" (4) Fixed window, 114" (5) Tilt-up concrete wall, 4" thick (6) Standard roof (7) Enhanced roof - 125 10 13 19 19 22 42 20 29 Octave Band TL (dB) - 250 500 &l(JQ 2000 12 15 16.5 18 17 17 20 33 21 24 26 26 19 23 27 26 25 27 31 23 42 45 52 57 24 28 32 34 35 48 51 53 4ooo 20 36 30 28 31 62 33 46 Est. STC 15 22 26 25 27 52 31 45 (1) Assumes 1" air gap on sides and bottom (2% area), 24 ga sheet metal (2) Assumes gasket material top and sides, 24 ga sheet metal; est. STC = 22 (3) (4) Aluminum frame, sealed, single pane windows (5) Solid concrete wall, Harris HB Noise Control, Fig. 31-14 (6) 5/8" plywood over steel bar trusses, est. (CA HB 1.3.3.5.4.2 similar to built-up roof) (7) 5/8" plywood over steel bar trusses, 5/8" gypboard ceiling (CA HB 1.3.3.5.4.5 similar to built-up roof) 4.0 BUILDING INTERIOR NOISE LEVELS Appendix A provides the calculation details for determining the interior noise levels in the building. The estimated values are averages; certain locations within the building may be slightly higher or lower than predicted. Table 3 below provides a summary of results. 10731 Old Saybrook Drive, San Diego, California 92129 Telephone & Fax (619) 672-2043 Report Number 0597-P9 c 6 July 7, 1997 Table 3 Predicted Interior Noise Levels Predicted Interior Noise Building Features JCNELl l-1st floor standard roll-up door 46.1 (standard) std roof 1/4" fixed glass 1-2nd floor standard roll-up door 46.7 (standard) std roof 1/4" fixed glass 2-1st floor standard roll-up door 49.6 (standard) std roof 1 1/4" fixed glass 2-2nd floor standard roll-up door 51.9 (standard) std roof 114" fixed glass 2-2nd floor standard roll-up door 46.3 (upgrade) upgraded roof (see below) 1/4" fixed glass Our findings based upon the analysis are as follows: 1. 2. 3. 4. 5. Required Interior Noise JCNEL) PasslFail 50 Pass 50 Pass 50 Pass 50 Fail 50 Pass Building 1 requires no upgrades to meet interior noise limits. First floor of Building 2 also requires no upgrades to meet interior noise limits. To comply with the 50 dBA CNEL limit, the standard roof construction must be upgraded in building 2, 2nd floor mezzanine office space to include 5/8" gypsum board or 5/8" plywood attached to underside of trusses. Standard 1/4" or similar, single glazed. fixed windows (with a minimum STC rating of 27) are sufficient in both buildings to meet average interior noise levels. Mechanical ventilation or air-conditioning is required in all buildings per UBC requirements. Air intake ducts must be designed in such a manner as to not degrade the acoustic integrity of the walVroof system. 10731 Old Saybrook Drive, San Diego, California 921 29 Telephone & Fax (619) 672-2043 Report Number 0597-F9 July 7, 1997 7 6. Localized sound fields in the 2nd floor office space may impact conversation and telephone use during noisy aircraft takeoff periods, even though the 50 dBA CNEL limit is met on average. The CNEL descriptor is a 24 hour average noise level. Exterior noise exceeding 75 dBA may occur during aircraft departures or flyovers. We strongly - recommend a layer of R-19 batt insulation be placed above the office dropped ceiling in the 2nd floor of Building 2, although this is not rewired. 10731 Old Saybrook Drive, San Diego, California 921 29 Telephone & Fax (61 9) 672-2043 Report Number 059749 July 7, 1993 APPENDIX A Interior Noise Level Prediction Calculations 10731 Old Saybrook Drive, San Diego, California 92129 Telephone & Fax (619) 672-2043 ~~ ~~ ’* Acoustech Consultants c Lot 41 Palomar Airport Centre I Project: I Lot 41 Palomar Airport Centre I Building: 1 IROOM Lindoor 46.1 I 1st hr 1/4” fixed glass 9433.00 62 concrete 18700.00 33 roof 25.8 24.8 0.7 32.9 1810.00 31 0.00 0.00 Building 1,lst Floor Standard Roof and Doors Acbustech Consultants - Lot 41 Palornar Airport Centre 1 I Project: /Lot 41 Palomar Airport Centre I Building: 1 IROOM Lindoor 46.7 2nd floor concrete 2034.00 42 0.00 0.00 I 500Herb ~ ~ roll-up door 36.1 39.3 3.0 28.7 1614.00 27 114" fixed glass 0.00 24 access door 0.00 15 roof 28 7500.00 concrete 45 2034.00 I nm 1 1OOOHerb roll-up door 0.00 26 access door 0.00 17 114" fixed glass roof 2034.00 52 concrete 7500.00 32 ~ ~~ 31 30.1 30.1 1.7 32.7 1614.00 "" 0.00 1/4" fixed glass 2034.00 57 concrete 7500.00 34 roof 31.9 30.7 1.7 30.0 1614.00 23 0.00 0.00 Building 1.2nd Floor Standard Roof 'a Acckrstech Consultants - Lot 41 Palornar Airport Centre I Pmject: lLot 41 Palomar Airport Centre I Building: 2 [ROOM Lindoor 49.6 lst lloor I Floor Area 26400 Building 2,lst Floor Standard Roof and Doors : Acoustech Consultants Lot 41 Palomar Airport Centre L I Project: lLot 41 Palomar Airport Centre I Building: 2 ]ROOM Lindoor 51.9 2nd floor Floor Ana 6600 i Building 2,hd Floor Staudard Roof ; ' Acwstech Consukants - - Lot 41 Palomar Airport Centre I Project: I Lot 41 Palomar Airport Centre 1 Building: 2 ]ROOM Lindwr 46.3 2nd floor Floor Area 6600 Building 2.2nd Floor Enhanced Roof J .’ * b THE CURRIE PARTNERS INC. A Real Estate Development Company 9820 Willow Creek Road, Suite 400 San Diego, California 9213 1 (619) 271-7050 Telephone (619) 578-4419 Fax FAX COVER LETTER DATE: FAX: Number of pages including cover sheet: 1 & If you do not receive a complete transmission, please call (619) 271-7050 ~ MESSAGE: