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08O. Appendix OP.O. Boa 17 • Helena, Montana 59624 Tel: (406) 457-0407 • Fax: (406) 442-1296 www.bigskyacousaa.com Big Sky Acoustics, uc January 4, 2012 Mr. Jeff Walla Stelling Engineers, Inc. 1372 Airport Road Kalispell, MT 59901 Re: Kalispell City Airport Airport Noise Contours BSA Project #09139 Dear Jeff: Big Sky Acoustics, LLC (BSA) has completed the noise contour analysis for the Kalispell city Airport. The attached report provides the details and results of the noise study. Thank you for your continued confidence in BSA. If you have any questions or comments regarding the information presented in the report, please do not hesitate to call me at (406) 457- 0407, or email me at sean@bigskyacoustics.com. Sincerely, Sean Connolly, P.E. (OR) BIG SKY ACOUSTICS, LLC Attachment P.O. Box 21 • Helena. Montana 59624 Tel: (406) 451-0401 • Fax: (406) 442-1296 www.hi gskyacousti cs.coiu Big Sky Acoustics, uc KALISPELL CITY AIRPORT NOISE CONTOUR ANALYSIS January 4, 2012 1.0 INTRODUCTION The Kalispell City Airport (KCA) is a general aviation airport, and its Master Plan is being updated to evaluate the airport's capabilities and to provide guidelines for the airport's overall maintenance, development and operation (Stelling 2011 a). Three development alternatives were recommended for further study in the Update: • Alternative A: Constructing a new runway alignment. • Alternative B: Improving the existing runway. • Alternative C: Relocating the KCA to a new site northwest of Kalispell. The City of Kalispell requested that noise contours be developed for the KCA alternatives to determine the potential noise impact of predicted airport operations on adjacent properties. Airport noise contours are used for land use planning purposes to ensure that noise -sensitive development does not occur too close to an airport. The noise contour analysis was conducted by Big Sky Acoustics, LLC (BSA), in accordance with Federal Aviation Administration (FAA) Order 5050.4A, The Airport Environmental Handbook. 2.0 NOISE TERMINOLOGY Noise levels are quantified using units of decibels (dB). Noise levels can also be expressed as A - weighted decibels (dBA). Humans typically have reduced hearing sensitivity at low frequencies compared with their response at high frequencies, and the A -weighting of noise levels closely correlates to the frequency response of normal human hearing. By utilizing A -weighted noise levels in a study, a person's response to noise can be assessed. Decibels are logarithmic values, and cannot be combined using normal algebraic addition. For example, the combined noise level of two 50-dBA noise sources would be 53 dBA, not 100 dBA, and the combination of a 50 dBA noise level and a 40 dBA noise level would still be 50 dBA. The day -night average noise level, DNL, is a single number descriptor that represents the constantly varying sound level during a continuous 24-hour period. The DNL includes a 10 dBA penalty that is added to noises that occur during the nighttime hours between 10:00 p.m. and 7:00 a.m., to account for people's higher sensitivity to noise at night when the background noise level is typically lower. Page I of 5 Kalispell City Airport Master Plan Update Big Sky Acoustics, LLC Noise Contour Analysis Airport noise contours are normally presented in terms of DNL values in units of A -weighted decibels, in increments of 5 dBA. The contours are based on the annual number of flight operations at an airport and the airport fleet mix. The FAA considers the DNL metric useful for airport noise studies because it uses a single number to describe the constantly fluctuating noise levels at a receiver location during an average 24-hour day. The use of DNL contours is meant to provide a general indication of impact and is not intended to determine the reaction of people due to individual events, such as a single take -off or landing. 3.0 FAA REQUIREMENTS The Aviation Safety and Noise Abatement Act of 1979 required the FAA to establish a single system for determining noise exposure at properties in the vicinity of airports, and the FAA was required to set up a standardized airport noise and land compatibility planning program. With the adoption of FAR Part 150, Airport Noise Compatibility Planning, the FAA established that noise contour maps would be used as a planning tool to determine if land located near airports is compatible with the operation of the airport, and to determine if noise -sensitive locations near airports would be negatively impacted by changes to an airport or its operations. This document determined that residences and schools should not be located within the DNL 65 dBA contour associated with an airport. The FAA's Airport Environmental Handbook does not require a noise exposure contour analysis for the KCA since its projected 24,754 annual flight operations in the Design Year 2030 (Stelling 2011a) do not exceed 90,000 annual propeller operations. However, the City determined that an analysis of the KCA noise contours would be beneficial for the Project. Please note that the predicted DNL contours for any airport do not precisely define impacts. The purpose of the noise contours, and specifically the DNL 65 contour, is to highlight potential incompatibilities between an airport and surrounding development, assess relative noise exposure levels, and provide guidance for the development of land -use control devices, such as zoning ordinances, subdivision regulations and building codes. 4.0 ANALYSIS The intent of this noise analysis was to determine the noise contours for each of the development alternatives. Each alternative includes the construction of a 3,600 foot runway, and the land acquisition necessary for potential future improvements and runway extensions. For the analysis, the number of flight operations and the fleet mix were evaluated, and used to calculate the contours. The location of the DNL contours were then overlayed on to figures from the Master Plan Update to compare the locations of the contours to the location of the airport property lines and land uses in the vicinity of the airport. 4.1 The Integrated Noise Model (INM) The FAA developed the Integrated Noise Model (INM) software to predict noise contours for airports. BSA used INM Version 7.0 for the KCA analysis. INM is designed to estimate the Page 2 of 5 Kalispell City Airport Master Plan Update Big Sky Acoustics, LLC Noise Contour Analysis average annual noise levels due to the operations at an airport. Therefore, differences between predicted and actual noise levels may vary on any given day because certain specific occurrences, such as number of flight operations, specific aircraft type, etc., may not be explicitly modeled in INM. To compute noise contours, INM uses the number of average annual flight operations, the type of aircraft using the airport, and the time of day that flight operations occur. The elevation of runway endpoints, the overall length of a runway, and the width of the runway to define the beginning and endpoint of flight operations on the runway were also entered into the model. The flight operations at an airport include approach, departure and touch-and-go operations that occur during an average day associated with a certain type of aircraft. Since the calculation of the DNL metric is based on the time of day when a noise -producing event occurs, flight operations are separated into those that occur during the daytime hours (7:00 a.m. to 10:00 p.m.) and nighttime hours (10:00 p.m. to 7:00 a.m.) for a 24-hour period. 4.2 Flight Operation Data The noise contours developed by BSA are based on the fleet mix and forecast flight operations stated in the the Master Plan Update (Stelling 2011 a). Based on additional information, 5% of operations occur at night, and the preferred runway at the existing KCA is Runway 13 (Stelling 2011b). Aircraft using Runway 13 take off to the southeast and arrive from the northwest. BSA assumed that 60% of all flight operations would use the Runway 13 orientation for Alternative B, and that 50% of those operations were departures and 50% were arrivals. Since the runway orientation of each alternative is similar, BSA assumed that Runway 12 would be the preferred orientation for Alternative A, and Runway 14 would be preferred for Alternative C. In the Master Plan Update, Table 4-9 included the estimated number of operations for each type of aircraft in the fleet mix for the current year 2011. Using the data in the table, BSA calculated the percentage of the total operations for each aircraft type. Since the length of the runway for each alternative is the same as the existing KCA runway (3,600 feet), BSA assumed the percentages would be similar in the Design Year 2030 for each alternative. Table 4-1 indicates the forecasted data that was input into the INM model to calculate the noise contours. The alternatives do not include extending the runway at this time, and operation data for aircraft that could utilize a longer runway, such as jets, were not provided (Stelling 2011 a). The Design Year of the project is 2030. Page 3 of 5 Kalispell City Airport Master Plan Update Noise Contour Analysis Table 4-1: Estimated KCA Fleet Mix and Operations Big Sky Acoustic, LLC "ClPercentage Percentage of Percentage of Design of Total Daytime Nighttime GroUV2 Tvpes of AircraftZ Operations Operations Operations A -I Single engine aircraft, such as 85% 95% 5% Cessna 172. B-I Twin engine aircraft, such as 0.4% 95% 5% Cessna 340 B-II Twin engine turboprop aircraft, 0.4/o 0 95% 5% such as Beechcraft Kine Air C90. Rotorcraft Helicopter, such as the Bell 206 14.2% 95% 5% series. Notes 1. Airport Reference Code. 2. Stelling 2011a. 5.0 RESULTS The predicted noise contours for each of the development alternatives are shown on Figures 1 through 4. As shown for each alternative, the DNL 65 contour will be located within the proposed airport boundary for Alternatives A and C in the Design Year 2030, and within the existing airport boundary for Alternative B in the Present Year 2011 and Design Year 2030. Therefore, the DNL 65 contour is not predicted to extend onto adjacent properties, and negative noise impacts should not occur on properties in the vicinity of the airport according to the FAA criteria. Although the FAA criteria is predicted to be met in the area surrounding Alternative C, noise annoyance in a community may be much greater than predicted when a new, unfamiliar noise source is introduced to an area. DNL adjustments or +10 to +15 dBA may be necessary to assess the true impact of the proposed Alternative C location (ISO 2003). Therefore, the predicted DNL 50 dBA contour shown on Figure 4 would be adjusted to DNL 60 to 65 dBA. Although several houses are shown just outside the DNL 50 (adjusted DNL 60-65) contour, the aircraft operations may still generate a negative community reaction. 6.0 STANDARD OF CARE To complete this report, BSA has endeavored to perform its work in a manner consistent with that degree of care and skill ordinarily exercised by members of the same acoustical profession currently practicing under similar circumstances. BSA makes no warranty, either express or implied, as to the professional services it has rendered to complete this report. For the completion of this report, BSA has used data provided by Stelling Engineers in performing services and is entitled to rely upon the accuracy and completeness thereof. Therefore, if the information (i.e., flight operation data, proposed runway configurations, aircraft Page 4 of 5 Kalispell City Airport Master Plan Update Noise Contour Analysis Big Sky Acoustics, LLC type, etc.) and assumptions used to create this report change, then the predicted noise contours may need to be reevaluated. 7.0 REFERENCES International Organization for Standardization (ISO). 2003. Acoustics — Description, measurement and assessment of environmental sound — Part 1: Basic quantities and assessment procedures. Standard Designation: 1996-1. Stelling Engineers (Stelling). 2011a. Kalispell City Airport Master Plan Update — Draft. Dated December 12, 2011. Viewed at City of Kalispell website htt://www,kalis ell.com/ma or and cily council/Ci A' ortInforrnation. h . December 27. Stelling Engineers (Stelling). 2011b. Email from Mike Beckhoff indicating percentage of night usage and preferred runway usage. November 23. Page 5 of 5 ;jr� -( K � • � r � 47 y� ��; a d ar � c a Y J J 4 . S * r uj a d ■ �1 4yip9J � _.. f eLe N uj CD LL r CD CV L QD Co a O Z Y V J J ry jut � � � a a■ v �W, ,per y J ' a� O M O N c Q C � m CO L C N i a0 0 in CD- 0 ¢„ a U O U aD •N Q Z Y _! Z 0 V J J -• c =) U cu aD a L N L Cc d Q 0 O Q �a o U U d CL (A N Z Y V J J L�!Iel