March 7, Mr. Vincent Mellusi Warshauer Mellusi Warshauer Architects 7 Skyline Drive Hawthorne, NY 10532

Transcription

1 Founder Vito V. Cerami ( ) Executive Board Victoria J. Cerami John D. Longman Stephen G. Lindsey Partners Alan M. Bjornsen Patricia M. Scanlon March 7, 2012 Mr. Vincent Mellusi Warshauer Mellusi Warshauer Architects 7 Skyline Drive Hawthorne, NY Ref: Chappaqua Station Development Environmental Noise / Façade Evaluation C&A Project #20177 Dear Mr. Mellusi: We have reviewed site plans and exterior building elevations for the residential development of the property in Chappaqua bounded by Quaker Rd (CT120), Hunts Place, the Saw Mill Parkway Northbound exit 32 ramp, and Metro North Railroad. For the purposes of this report, the Saw Mill Parkway property line shall be considered the Northern orientation, as reflected on the site plan drawing A-1 dated February 7, Subsequent to our monitoring of the environmental noise for a 24 hour period between the 1 st and 2 nd of March 2012, we present the following findings, comments and recommendations with respect to the construction and performance of exterior walls and windows of this residential building. 1.0 EXECUTIVE SUMMARY Based on noise levels measured on site and our review of façade construction methods, we find that dwelling windows should be selected for a sound transmission rating of not less than OITC-28 in order to comply with Federal and State guidelines for noise impacts on residences. It is our finding that the Marvin Integrity double-hung windows identified as the basis-of-design will not meet this performance requirement, and should not be used unless in conjunction with a robust storm window system subject to our review. 2.0 ACOUSTIC CRITERIA NY SEQRA and FHWA guidelines establish that residential exterior constructions should provide an interior noise level of not greater than 45 dba, due to environmental noise sources such as highways and railways, based on the loudest hourly L 10 noise levels at the site. L 10 is a statistical parameter in a noise measurement reflecting the level exceeded only 10% of measurement period and commonly used to describe environmental activity noise levels. The A-weighted noise reduction can be calculated by octave-band noise data measured from the site and transmission loss values of building exterior components. Where octave band data are not available however, the use of an Outdoor-Indoor Transmission Class rating is typically accepted as a common and more conservative method of analysis. 404 Fifth Avenue New York NY T ceramiassociates.com

2 3.0 NOISE SURVEY During a 24 hour period from March 1 to 2, 2012, we monitored noise levels at two locations on the property. These locations were (1) at the southern edge of the proposed building footprint, 20 feet from the railroad tracks and 10 feet above grade, and (2) on top of the earthen embankment to the west of the northern edge of the proposed building footprint, 45 feet from the nearest traveling lane on Saw Mill Parkway and approximately 3 feet above the road surface elevation of Quaker Rd. A map showing these locations is provided in the image below. Our worst case measurement occurred during the 7-8 hour on the northern edge of the property with a level of 77 dba, indicating a minimum façade noise reduction requirement of 32 dba. See the attached Figure 1 for more detail. Noise Monitoring Locations # 1 # 2 Noise Test Results dba Loudest Hour Measured Warshauer Mellusi Warshauer Architects Page 2 of 4 Chappaqua Station Development Project #20177 March 7, 2012

3 4.0 Analysis & Façade Requirements We understand that the standard exterior façade is intended to be built upon 6 wood framing with R19 fiberglass insulation, 5/8 gypsum board interior walls, and exterior cladding comprising sheathing board, minimum 1 Styrofoam insulation, and either HardiePlank fibre-cement siding or 4 brick exterior finish. We anticipate this assembly to have a Sound Transmission Class of approximately STC-43 and an Outdoor-Indoor Transmission Class of OITC-36 for the HardiePlank façade, which will be less resistant to sound transmission than 4 thick brickwork. We further understand that window glazing shall comprise not more than 25% of any exterior face. Based on these factors, we find that the window selections should be selected for a minimum rating of OITC-28 to comply with the noise requirements and achieve a composite overall noise rating of OITC-32 or better. We understand that the current basis-of-design window assembly is a Marvin Integrity double-hung window, which uses an insulated glazing nominally ¾ thick utilizing annealed glass on each side 3.1mm thick. The manufacturer provides a sound rating of OITC-23 for the fiberglass framed IFDH double-hung window. We advise that these windows will not comply with the noise requirements unless they are provided with storm windows at least using ¼ thick glass and an air gap of not less than 2 from the double hung window glass. As examples, we have noise test data on file for the following window types, which have acceptable noise ratings. Example Acceptable Double Hung Window Products Manufacturer Model Total Glazing Glass Air Gap Glass OITC Skyline /4 3/16 7/8 3/16 28 Marvin CUDH 11/16 3/16 3/8 1/8 28 Harvey Acoustic Vinyl DH 3 * 1/8 1/2 1/4 33 *Harvey Acoustic window includes integral 5/32 storm window opposite min 2 air gap We will be glad to review any alternate window selections upon request. Any windows rated at less than OITC-28 must include a full test report with 1/3 octave band transmission loss values. Warshauer Mellusi Warshauer Architects Page 3 of 4 Chappaqua Station Development Project #20177 March 7, 2012

4 This concludes our comments at this time. Please do not hesitate to contact us with any further questions, comments, or concerns. Very truly yours, Thomas E. Kaytt Senior Associate J:\ \20177\correspondence\Environmental Noise-Facade Study_AC_TEK_001.doc Warshauer Mellusi Warshauer Architects Page 4 of 4 Chappaqua Station Development Project #20177 March 7, 2012

5 Chappaqua Station Development C&A Project # March 7, 2012 Figure 1: Measured Noise Levels, LAS10 Measured Outdoor Noise Levels at Roof Edge of 508 West 24th Street (6/21/2011-6/22/2011) ' from Overpass Elevation 20' from Train Tracks, 10' Above Grade 90 Sound Pressure Level (dba re 20 μpa) :00 6:00 7:00 8:00 9:00 10:00 11:00 12:00 1:00 2:00 3:00 4:00 5:00 Time Period 6:00 7:00 8:00 9:00 10:00 11:00 12:00 1:00 2:00 3:00 4:00 Cerami & Associates, Inc. 24-hour Time History.xls, Time History Chart

6 Sound Insulation Prediction (v6.4) Program copyright Marshall Day Acoustics 2010 Cerami & Associates - Key No Margin of error is generally within STC +/- 3 db Job Name: Job No.: Date: 5 Mar 12 File Name: insul.ins 7.47 in Page No.: Initials:tkaytt Notes: STC 43 OITC in System description Panel 1 Outer layer: 1 x 0.63 in Type X Gypsum Board- (m=2.24 lb/ft2, fc=2511 Hz, damping=0.01) Cavity: Timber 16 in, Infill 3" fiberglass (0.6 lb/ft3) Thickness 3 in Panel 2 Inner layer: 1 x 0.59 in OSB (Oriented Strand Board)- (m=1.74 lb/ft2, fc=1651 Hz, damping=0.03) Panel 2 Outer layer: 1 x 0.25 in Fibre Cement (m=2.03 lb/ft2, fc=4724 Hz, damping=0.01) Mass-air-mass resonant frequency =59 Hz Panel Size 8.9x13 ft frequency (Hz) TL(dB) TL(dB)

7 Sound Insulation Prediction (v6.4) Program copyright Marshall Day Acoustics 2010 Cerami & Associates - Key No Margin of error is generally within STC +/- 3 db Job Name: Job No.: Date: 7 Mar 12 Page No.: Initials:tkaytt Notes: File Name: exterior wall - 4inch brick face.ins in STC 53 OITC in System description Panel 1 Outer layer: 1 x 0.63 in Type X Gypsum Board- (m=2.24 lb/ft2, fc=2511 Hz, damping=0.01) Cavity: Timber 16 in, Infill 3" fiberglass (0.6 lb/ft3) Thickness 3 in Panel 2 Inner layer: 1 x 0.59 in OSB (Oriented Strand Board)- (m=1.74 lb/ft2, fc=1651 Hz, damping=0.03) Panel 2 Outer layer: 1 x 4.33 in Brick (m=36.04 lb/ft2, fc=250 Hz, damping=0.00) Mass-air-mass resonant frequency =48 Hz Panel Size 8.9x13 ft frequency (Hz) TL(dB) TL(dB)