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Home My WebLink AboutPIP 95-09; Homes for Industry Lot 40; Planned Industrial Permit (PIP) (9)ACOUSTECH CONSULTANTS REPOW NO. 1295-P33 Acoustical Analysis Report for Two Proposed Buildings on Lots 39 & 40 Airport Business Center, Carlsbad Lot 39 - MS95/05~UD95/0~1P95/08 Lot 40 - CT95/04/PUD95/03/PIP95/09 December 18, 1995 Prepared For: Mr. Dennis Glaser St. Georges Holdings 2223 Avenida de la Playa La Jolla, California 92037 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 ST Report Number 1295-P33 December 18,1995 1.0 BACKGROUND 1 1.1 Purpose This report provides an evaluation of the interior noise levels expected for two proposed industrial buildings to be located adjacent to McClellan-Palomar Airport in the Airport Business Center 1.2 Requirements SANDAG has reviewed proposals for manufacturing buildings on lots 39 and 40 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 is forecasted to increase and cover portions of these lots. The buildings proposed for construction within the 75 dBA CNEL contour should be attenuated to an interior noise level of 50 dBA CNEL. 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 Kellogg Avenue. 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. 2.3 Building Characteristics The "large" building has a square footage of 10,OOO square feet while the "small" building is approximately 5OOO square feet. Both buildings consist of tilt-up concrete walls and an offidreception area with glass front. Key noise transmission features include the mf, a roll-up access door, and windows. Table 1 below provides the building elements and relevant areas. 10731 Old Saybrook Drive, San Dm, California 92129 Telephone & Fax (619) 672-2043 Report Number 1295433 December 18,1995 3 Table 1 Areas & STC's of Building Elements (Before Upgrades) Building Element Estimated STC Areas, ft2 B1 B2 (1) Roll-up Door (standad) 15 AccessDoor (standad) 26 (2) Fixed Glass (office &walls) 27 (3) Roof 29 Concrete (4"-57 46 168 168 21 21 47 1 576 5029 9987 5180 7501 (1) Est. 24 ga. sheet metal, minimal gasket (2) Fixed 1/4" thick single pane (3) 2"x6" joists; rooftop 38" plywood with paper and waterproof coating Building elements which have the greatest impact on sound transmission, in descending order are: 1. roll-up door 2. roof 3. windows The roll-up door, though small in area, generally provides poor sound insulation due to leakage at the perimeter. A higher-quality "cold weather" door may be required. The large area of the roof results in substantial noise transmission. 3.0 INTERIOR NOISE ESTIMATION METHODOLOGY 3.1 Prediction Technique To estimate the interior noise in the building, we assume that the roof and exterior walls may receive up to 75 dBA CNEL. The interior noise (Li,) 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 surfam area of the various building elements A = the room absorption in Sabins In practice, the composite transmission loss (TLJ for the building exterior elements is calculated based upon the individual transmission loss and areas. 10731 Old Saybrook Drive, San -0, California 92129 Telephone 81 Fax (619) 672-2043 9. Report Number 1295433 December 18,1995 4 To calculate the composite transmission loss of a multi-element wall, the following equations are employed: where TL, is the transmission loss of the multi-element wall or roof in dB. zc is the composite wall or roof transmission coefficient. S,,S2, -ST are the areas of individual wall or roof elements. zl, z2, -- zn are the sound transmission coefficients of the individual elements. ST = total wall or roof area; S, +S2 --- Sn The terms zl, z2, -- zn can be calculated from the element STC values or from octave-band single element transmission loss values by solving the equation: = l/antilog,, [STC/lO] OR, = t l/antiiog,o [Tu101 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 dBA CNEL is estimated to consist of the following octave band levels: Octave Band CF Est. Linear Spectrum Est. A-Wtd Spectrum 125 250 500 1000 2000 4Ooo 81) 78 70 66 64 62 64 68 67 66 65 63 10731 Old Saybrook Drive, San Diego, CdRmia 92129 Telephone & Fax (619) 672-2043 .. Report Number 1295-P33 December 18,1995 5 The transmission loss of standard and upgraded building elements is as follows: Table 2 Transmission Loss of Building Elements Octave Band TL (dB) - 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 - 2s - 500 10 12 15 13 17 17 19 21 24 19 19 23 22 25 27 42 42 45 15 22 27 30 37 42 - 1006 16.5 20 26 27 31 52 32 46 - 2000 18 33 26 26 23 57 35 49 - 4Ooo 20 36 30 28 31 62 30 52 Est. STC 15 .* 22 26 25 27 52 29 44 (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 2"x6" joists, est. (7) 5/23" plywood over 2"x6" joists, R-19 insulation, 38" gypboard on resilient channels (Cal. HB 2.1.2.2.1.2, degraded at LF for 6" v. 8" joists) 4.0 BUILDING INTERIOR NOISE LIMITS 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, Cdifmii 92129 Telephone & Fax (619) 672-2043 -. Report Number 1295P33 December 18,1995 6 Table 3 Predicted Interior Noise Levels Building Features Small-5000ft~ standard roll-up door (StatldWtl) with air gaps std roof Small upgrade roll-up door (UPgndL.) with seals upgraded roof (seebelow) Large- I 0,000 ft' standard roll-up door (SmdTd) with air gaps Large upgrade roll-up door (qm-~) with seals std roof upgraded roof (seebelow) Predicted Interior Noise JCNEL) 58.3 48.9 60.9 50.0 Required Interior Noise JCNEL) PasslFaiI 50 Fail 50 Pass 50 Fail 50 Pass Our findings based upon the analysis are as follows: 1. The roll-up door and roof design have the greatest affect on the interior noise levels. 2. Whdows and standard doors have only a small affect on the overall interior noise levels in the building. 3. Standard 1/4" or similar, single glazed, fixed windows are sufficient to meet average interior noise levels. 4. Upgraded roll-up doors and substantially upgraded roofs are required to comply with the 50 dBA CNEL limit. 5. The roll-up door should have no visible air gaps. A cold weather, high- qr~al itv door is required. Alternatively, a special custom edge seal for a standard door will be necessary. 6. The standard roof construction must be upgraded to include R-19 batt insulation between joists and 5/8" gypsum board on 1/2" resilient channels attached to the joists and spaced 24" O.C. 7. We recommend a layer of R-19 batt insulation be placed above the office/entry dropped ceiling. 10731 Old Saybrook Drive. San Dqo, California 92129 Telephone & Fax (619) 672-2043