CHAPTER 5.0 ENVIRONMENTAL CONSEQUENCES

Transcription

1 CHAPTER 5.0 ENVIRONMENTAL CONSEQUENCES The potential environmental impacts resulting from the construction and operation of the No-Action Alternative and Build Alternatives 3 and 4 at Washington Dulles International Airport (IAD) are presented in this chapter. For this Draft Environmental Impact Statement (DEIS), the following study year and alternative scenarios are examined. Study Year Alternative Description No-Action Build Alternative 3 Build Alternative 4 No airside or landside improvements would be constructed under this alternative. Construction of a north-south oriented runway (1W/19W), approximately 9,473 feet in length, located 4,300 feet west of existing Runway 1L/19R; Construction of a new 10,500-foot east-west oriented runway (12R/30L) located 4,300 feet south of existing Runway 12/30; Construction and operation of a new full-length parallel taxiway on the east side of new Runway 1W/19W; Construction and operation of taxiway connectors between new Runway 1W/19W and existing Runway 1R/19L; Construction and operation of a new full-length parallel taxiway on the north side of new Runway 12R/30L; Construction and operation of taxiway connectors between new Runway 12R/30L and existing Runway 12/30; Construction and operation of crossfield taxiways between existing Runway 30 and Taxiway J5 ; Installation and operation of navigational aids (NAVAIDS) for new Runways 1W/19W and 12R/30L; Tier 3 Concourse development; Extension of the automated people mover (APM) to the Tier 3 Concourse; Support facility improvements; Relocation of National Oceanic and Atmospheric Administration (NOAA)/National Weather Service (NWS) facilities (NOAA will prepare separate National Environmental Policy [NEPA] documentation from this FAA Environmental Impact Statement [EIS] that will contain an evaluation of environmental impacts associated with relocated NOAA/NWS facilities), and property acquisition. Construction of a north-south oriented runway (1W/19W), approximately 9,218 feet in length, located 5,000 feet west of existing Runway 1L/19R; Construction of a new 10,500-foot east-west oriented runway (12R/30L) located 4,300 feet south of existing Runway 12/30; Construction and operation of a new full-length parallel taxiway on the east side of new Runway 1W/19W; Construction and operation of taxiway connectors between new Runway 1W/19W and existing Runway 1R/19L; Construction and operation of a new full-length parallel taxiway on the north side of new Runway 12R/30L; Construction and operation of taxiway connectors between new Runway 12R/30L and existing Runway 12/30; Construction and operation of crossfield taxiways between existing Runway 30 and Taxiway J5 ; Installation and operation of NAVAIDS for new Runways 1W/19W and 12R/30L; Tier 3 Concourse development; Extension of the APM to the Tier 3 Concourse; Support facility improvements; Relocation of NOAA/NWS facilities (NOAA will prepare separate NEPA documentation from this FAA EIS that will contain an evaluation of environmental impacts associated with relocated NOAA/NWS facilities), and property acquisition. X X X X W:\ _Dulles\DEIS\Ch_5\Ch_5.doc 5-1

2 The year 2010, examined for all the alternatives, is the threshold year used for the implementation of the alternatives. All environmental and social impact categories were evaluated for this study year. The potential impacts of the alternatives are identified in the following 23 impact categories. Each subsection begins with a brief overview of impacts (printed in bold), followed by methodology, impact analysis, and a discussion of whether mitigation measures are needed or not. Mitigation measures are presented in Chapter 6.0, Mitigation, of this EIS. 5.1 NOISE OVERVIEW OF IMPACTS FAA Orders E and A establish the Threshold of Significance for noise impacts to be a 1.5 Day-Night Average Sound Level (DNL) or greater increase in noise at any noise-sensitive areas within the 65 DNL contour (U.S. Department of Transportation [DOT], FAA, 1985, 2004). FAA Order E considers that if an increase in the DNL of 1.5 dba occurs at any noise-sensitive area within the 65 DNL contour, further analysis is warranted. To comply with FAA s guidance provided in E and the recommendations of the 1992 Federal Interagency Committee on Noise (FICON), noise-sensitive areas between 60 and 65 DNL should be evaluated for increases of 3.0 DNL or greater if an increase of 1.5 DNL occurs at any noise-sensitive area within the 65 DNL. To comply with guidance provided in FAA Order E, for proposed air traffic actions above 3,000 feet above ground level (AGL), potential noise impacts resulting from changes in airport arrivals and departures should be disclosed. Noise-sensitive areas between 45 and 60 DNL should be evaluated for increases of 5.0 DNL or greater. Off-airport aviation-related noise impacts are not anticipated with any of the alternatives. Off-airport acreage would consist of approximately 233, 206, and 216 acres of non-noise-sensitive land within the 65 DNL contour for the No-Action Alternative, Build Alternative 3, and Build Alternative 4, respectively. No residences in Loudoun or Fairfax County and no noise-sensitive receptors would exceed the 1.5 DNL Threshold of Significance within the 65 DNL contour. Even though no residences or other noise-sensitive facilities would exceed the 1.5 DNL Threshold of Significance within the 65 DNL contour, for the purposes of fully disclosing potential effects of the Build Alternatives, different contours were generated to identify noise-sensitive areas that would be exposed to increases of 3.0 db or greater between the 60 and 65 DNL, and 5.0 db or greater between the 45 and 60 DNL. Increases of 3 DNL or greater between 60 and 65 DNL, as well as increases of 5 DNL or greater between 45 and 60 DNL would occur for both Build Alternatives 3 and 4. These increases do not exceed FAA s Threshold of Significance for noise impacts. However, both FAA and Metropolitan Washington Airports Authority (MWAA) acknowledge that people may be adversely affected by these increases in aircraft noise levels associated with Build Alternatives 3 and 4. There are no improvements to local roads, highways, or railroads associated with the Build Alternatives that would not also occur under the No-Action Alternative. Therefore, the Build Alternatives would not result in non-aviation-related noise impacts when compared to the No-Action Alternative. W:\ _Dulles\DEIS\Ch_5\Ch_5.doc 5-2

3 Since none of the alternatives would result in significant noise impacts, mitigation measures are not required. However, mitigation could be considered for noise-sensitive areas that exceed the 3.0 DNL increase between 60 and 65 DNL. Fifteen residential parcels in Loudoun County would experience increases greater than 3.0 dba between the 60 and 65 DNL, relative to the No-Action Alternative. No residences in Fairfax County or any noise-sensitive receptors in Loudon or Fairfax County would exceed the 3.0 DNL criteria between the 60 and 65 DNL. Therefore, mitigation could be considered for the fifteen residential parcels in Loudon County. Mitigation is not warranted for noise-sensitive areas that exceed the 5.0 DNL increase between 45 and 60 DNL METHODOLOGY Appendices D-3 through D-6 describe in detail the sources and derivation of the Integrated Noise Model (INM) input data for future (2010) conditions including airport layout, weather, flight operations, runway use, flight tracks, track use, flight profiles, and run-up operations/profiles. Appendix D-3 contains information that is common to all scenarios for year 2010 (i.e., No-Action and Build Alternatives 3 and 4). Data that is specific to each scenario is presented in Appendices D-4 through D-6. INM Version 6.1 was used to model each of the alternatives. Sections through summarize the data in these appendices. Future flight tracks and their utilization were initially identified from the Potomac Consolidated Terminal Radar Approach Control (TRACON) Airspace Redesign Final Environmental Impact Statement (FEIS) (FAA, 2002). Through extensive consultation, coordination, and cooperation with the Potomac Consolidated TRACON (PCT), Dulles Airport Traffic Control Tower (IAD ATCT), FAA Washington Airports District Office, and MWAA and their consultants, details of projected future conditions were refined for the alternatives presented in this DEIS. Between May 2003 and June 2004, coordination included five meetings, three conference calls, and distribution of numerous data packages containing iterations of flight track locations and utilization, operational flows, and runway utilization. The final flight track locations, operational flows, and runway and flight track utilizations were all endorsed by the aforementioned coordinating agencies INM Input Data Common to All Alternatives Modeled weather conditions, flight operations, flight profiles, and run-up operations were common to all of the alternatives. Airport layout, runway use, flight tracks, and track use varied by each alternative because of the different runway configuration associated with each alternative. Weather - The INM default values for temperature (57.9 degrees Fahrenheit [ F]), pressure (29.92 inches of mercury), humidity (70 percent), and headwind (8 knots) were used to model noise levels for all alternatives at IAD in The default airport temperature is computed using the International Standard Atmosphere equation for standard-day temperature versus altitude. The International Standard Atmosphere temperature is 59 F at mean sea level and it gets progressively colder at higher airport elevations. The default airport pressure is inches of mercury at all airport elevations because atmospheric pressure is referred to sea level. The default average headwind is 8 knots, which is the value used in the SAE-AIR 1845 equations. INM uses temperature, pressure, and headwind when computing procedural profiles. Humidity is only used in calculating atmospheric absorption. W:\ _Dulles\DEIS\Ch_5\Ch_5.doc 5-3

4 Flight Operations - Annual operations for the future (year 2010) condition would total 568,411 1 as shown in Table and Appendix D-3, Table D-3.1. Jet operations would account for approximately 89 percent of the total while nighttime operations would account for 10 percent of the total. Appendix D-3, Tables D-3.2 through D-3.5 list the annual departure and arrival operations by representative INM aircraft type for air carrier/air taxi, cargo, general aviation, and military, respectively. Flight Profiles - Flight profiles model the vertical paths of aircraft during departure and arrival to determine the altitude, speed, and engine thrust or power of an aircraft at any point along a flight track. INM uses this information to calculate noise exposure on the ground. Profiles are unique to each aircraft type and are based on user (e.g., airline) operational procedures, temperature, and aircraft weight. Standard INM departure and arrival profiles were used for this analysis. Stage (or trip) length was derived from the destinations of forecasted departures, which determined the standard profile for departing aircraft. See Appendix D-2, Table D-2.10 for the definition of stage length. Departing aircraft were modeled beginning with takeoff roll and ending when the aircraft reached an altitude of 10,000 feet above field elevation. Arriving aircraft were modeled with a standard 3-degree descent angle for all approaches, beginning at an altitude of 6,000 feet above field elevation and ending with the aircraft touchdown and roll-out. Run-Up Operations - Prior to flight or during maintenance, aircraft engines are sometimes operated (i.e., run ) to check their performance. These engine operations, simply called run-ups, are typically cyclic, i.e., power/throttle is increased and decreased, and can last several minutes. Maintenance run-ups are often performed at nighttime. Annual maintenance run-ups are listed in Appendix D-3, Table D-3.6 for the Year 2010 future condition. The maintenance run-up operations modeled for the existing condition (Appendix D-2, Table D-2.11) were factored by the increase or decrease in flight operations of the associated aircraft types. Identical to the existing condition, maintenance run-ups would be performed at the hold-short areas of Runways 19L and 30 with the aircraft oriented at runway heading. High-power run-ups would last no more than 10 minutes each, but would occur primarily during the nighttime period. Approximately four high-power run-ups, on average, would be conducted every night INM Input Data Specific to the No-Action Alternative Airport Layout - The three existing runways at IAD would remain unchanged for the No-Action Alternative. These runways were described in Section and in Appendix D-4. Aircraft Operational Flows - IAD would operate in four primary aircraft operational flows, as shown on Figure These operational flows are influenced mainly by wind speed and direction, cloud ceiling, and visibility. To account for the differences in operational demand during an average annual 24-hour period where the activity forecast estimates 94 average hourly operations during the daytime (7:00 am until 10:00 pm) and only 17 average hourly operations during the nighttime (10:00 pm until 7:00 am), IAD ATC provided separate flow utilizations for daytime and nighttime periods. Overall, the Mixed, North, and South Flows would be in use 99 percent of the time. Northwest Flow occurs when high-speed winds from the northwest prevent aircraft from operating on the north-south runways, and accounts for the remaining one percent of operations. Appendix D-4, Table D-4.2 shows the percentage of operations assigned to each flow for the No-Action Alternative. 1 Differs by one operation with the forecast (568,410) due to rounding. W:\ _Dulles\DEIS\Ch_5\Ch_5.doc 5-4

5 TABLE SUMMARY OF ANNUAL AIRCRAFT FLIGHT OPERATIONS (2010) Aircraft Arrival Departure Total Grand Family Aircraft Category Day Night Total Day Night Total Day Night Total Air Wide-Body Jet 22,079 4,626 26,705 22,784 3,920 26,704 44,863 8,546 53,409 Carrier/ Narrow-Body Jet 71,558 8,422 79,980 73,904 6,077 79, ,462 14, ,961 Air Taxi Regional Jet 101,271 10, , ,610 6, , ,881 16, ,574 and Cargo Commercial Turboprop 20,551 2,232 22,783 21,226 1,556 22,782 41,777 3,788 45,565 Business Jet 26,704 4,346 31,050 26,704 4,346 31,050 53,408 8,692 62,100 General Twin-Engine Turboprop 3, ,099 3, ,099 7,048 1,150 8,198 Aviation/ Twin-Engine Air Taxi (Non-Turbo) Prop 2, ,250 2, ,250 5, ,500 Single-Engine Prop , ,902 Military Jet 2, ,550 2, ,552 5, ,102 Turboprop 1, ,550 1, ,550 3, ,100 Total Number 253,400 30, , ,467 23, , ,867 54, ,411 Day/Night Distribution 89% 11% 100% 92% 8% 100% 90% 10% 100% Day = 7:00 a.m. to 10:00 p.m. Night = 10:00 p.m. to 7:00 a.m. Minor differences between total arrivals and total departures may exist due to rounding. Source: URS Corporation, (See Appendix D-3) W:\ _Dulles\DEIS\Ch_5\Ch_5.doc 5-6

6 Runway Use - The modeled annual average daily utilization of the three existing runways at IAD are summarized in Table During the daytime, most of the arrivals (55 percent) would use Runway 19R and most of the departures (50 percent) would use Runway 19L. During the nighttime, most of the arrivals (38 percent) would use Runway 12 and most departures (61.5 percent) would use Runway 19R. The 2010 No-Action daytime and nighttime runway utilization is shown in Appendix D-4, Figure D-4.3. Overall runway utilization by equivalent operations is shown in Appendix D-4, Figure D-4.4. TABLE SUMMARY OF ANNUAL AVERAGE DAILY RUNWAY UTILIZATION (2010) FOR THE NO-ACTION ALTERNATIVE No-Action Alternative All Aircraft Daytime Nighttime Equivalent Operations** Runway Status Arrival Departure Arrival Departure Arrival Departure 1L Existing 9% 4% 11.5% 3% 10.5% 3.3% 19R Existing 55% 0% 28.6% 61.5% 40.3% 29.5% 1R Existing 14% 3% 11.5% 0.5% 12.5% 1.6% 19L Existing 11% 50% 9.4% 10% 10.3% 31.1% 12 Existing 10% 0% 38% 0% 25.4% 0% 30 Existing 1% 43% 1% 25% 1% 34.5% Total 100.0% 100.0% 100.0% 100.0% 100.0% 100.1% Note: **Equivalent operations equal daytime operations plus ten times nighttime operations (accounting for the DNL nighttime weighting factor). Source: PCT; Dulles ATCT, Flight Tracks - Flight tracks are the aircraft s actual path through the air projected vertically onto the ground. INM simulates the operation of the airport by flying the aircraft along relatively small numbers of flight tracks representing the large number of flight paths actually used by aircraft due to weather, traffic levels, pilot technique, and differing aircraft performance capabilities. These flight tracks do not represent the precise paths flown by all aircraft utilizing IAD. Instead, they represent the primary and average daily flight corridors for the airport. A flight corridor may be very wide. This characteristic of flight tracks to form a wide corridor is called dispersion. The modeled annual average daily departure and arrival flight tracks for the No-Action Alternative would remain effectively unchanged relative to the existing condition, except for the addition of high left downwind tracks on the west side of IAD. Appendix D-4, Figures D-4.5 through D-4.9 depict modeled departure and arrival flight tracks, with their associated dispersion, for each of the four operational flows described above. The primary flight tracks are shown in these figures as solid lines, while the dispersion tracks are shown as dashed lines. Areas not covered by either solid or dashed lines may or may not be subject to aircraft over-flights; flight tracks were not modeled in these areas due to their extremely infrequent or non-existent use. Track Use - Tables D-4.3 and D-4.4 of Appendix D-4 present utilization percentages of departure and arrival flight tracks, respectively, for the No-Action Alternative. 5-7

7 INM Input Data Specific to Build Alternative 3 Airport Layout - In addition to the three existing paved operational runways, 1R/19L, 1L/19R, and 12/30, Build Alternative 3 would add two new runways. The proposed north-south runway would be located on the western side of the airport and is referred to as Runway 1W/19W for the purpose of this DEIS only to minimize confusion with the existing runway designations. Ultimately, the proposed north-south runway would be designated Runway 1L/19R, while the existing Runway 1L/19R would be re-designated Runway 1C/19C. The proposed east-west runway would be located on the southern side of the airport and designated Runway 12R/30L. Existing Runway 12/30 would be re-designated as Runway 12L/30R. For Build Alternative 3, Runway 1W/19W would be 4,300 feet west of Runway 1L/19R and have a length of approximately 9,473 feet. The northern threshold of Runway 1W/19W would be parallel to the existing Runway 1L/19R. Runway 12R/30L would be 4,300 feet southwest of existing Runway 12/30 and have a length of 10,500 feet. Figure shows the Build Alternative 3 runway layout. The additional runways and their lengths, for Build Alternative 3 at IAD, are presented in Appendix D-5, Table D-5.1. Aircraft Operational Flows - IAD would operate in four primary aircraft operational flows, as shown on Figure Appendix D-5, Table D-5.2 shows the percentage of operations assigned to each flow for Build Alternative 3. Runway Use - A summary of the modeled annual average daily utilization of the runways at IAD for Build Alternative 3 is presented in Table Runway use among the Build Alternatives would be identical. During the daytime, most of the arrivals (30 percent) would use Runway 19W and the same proportion of departures (27 percent) would use Runways 19L, 30L, and 30R. During the nighttime, most of the arrivals (38 percent) would use Runway 12L and most departures (62 percent) would use Runway 19R. The 2010 Build Alternative 3 daytime and nighttime runway utilization is shown in Appendix D-5, Figure D-5.5. Overall runway utilization by equivalent operations is shown in Appendix D-5, Figure D-5.6. Flight Tracks - Appendix D-5, Figures D-5.7 through D-5.18 depict modeled departure and arrival flight tracks with their associated dispersion tracks for each of the operational flows described above. Track Use - Appendix D-5, Tables D-5.3 and D-5.4 present utilization percentages of departure and arrival flight tracks, respectively, for Build Alternative INM Input Data Specific to Build Alternative 4 Airport Layout - In addition to the three existing paved operational runways, 1R/19L, 1L/19R, and 12/30, Build Alternative 4 would add two new runways. The proposed north-south runway would be located on the western side of the airport and is referred to as Runway 1W/19W for the purpose of this DEIS only to minimize confusion with the existing runway designations. Ultimately, the proposed north-south runway would be designated Runway 1L/19R, while the existing Runway 1L/19R would be re-designated Runway 1C/19C. The proposed east-west runway would be located on the southern side of the airport and designated Runway 12R/30L. Existing Runway 12/30 would be re-designated as Runway 12L/30R. 5-8

8 TABLE SUMMARY OF ANNUAL AVERAGE DAILY RUNWAY UTILIZATION (2010) FOR BUILD ALTERNATIVES 3 AND 4 Runway Status Build Alternatives 3 and 4 All Aircraft Daytime Nighttime Equivalent Operations** Arrival Departure Arrival Departure Arrival Departure 1L Existing 16% 0.5% 12% 3% 13.5% 1.5% 19R Existing 23% 11% 29% 62% 26.2% 35.1% 1R Existing 16% 0.5% 12% 0% 13.5% 0.4% 19L Existing 8% 27% 9% 10% 8.6% 19.1% 12L Existing* 3% 0% 38% 0% 22.1% 0% 30R Existing* 0% 27% 0% 25% 0.6% 25.9% 1W Proposed 1% 7% 0% 0% 0.5% 3.8% 19W Proposed 30% 0% 0% 0% 13.4% 0% 12R Proposed 3% 0% 0% 0% 1.2% 0% 30L Proposed 0% 27% 0% 0% 0.4% 14.2% Total 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% Notes: * New designation. **Equivalent operations equal daytime operations plus ten times nighttime operations (accounting for the DNL nighttime weighting factor) Sources: PCT; Dulles ATCT, For Build Alternative 4, Runway 1W/19W would be 5,000 feet west of Runway 1L/19R and have a length of approximately 9,218 feet. The northern threshold of Runway 1W/19W would be parallel to existing Runway 1L/19R. Runway 12R/30L would be 4,300 feet southwest of existing Runway 12/30 and have a length of 10,500 feet. Figure shows the runway layout of Build Alternative 4. The additional runways and their lengths, for Build Alternative 4 at IAD, are presented in Appendix D-6, Table D-6.1. Aircraft Operational Flows - IAD would operate in four primary aircraft operational flows, as shown on Figure Appendix D-6, Table D-6.2 shows the percentage of operations assigned to each flow for Build Alternative 4. Runway Use - A summary of the modeled annual average daily utilization of the runways at IAD for Build Alternative 4 is presented in Table Runway use among the Build Alternatives would be identical. The 2010 Build Alternative 4 daytime and nighttime runway utilization is shown in Appendix D-6, Figure D-6.5. Overall runway utilization by equivalent operations is shown in Appendix D-6, Figure D-6.6. Flight Tracks - Figures D-6.7 through D-6.18 depict modeled departure and arrival flight tracks with their associated dispersion tracks for each of the operational flows described above. Track Use - Appendix D-6, Tables D-6.3 and D-6.4 present utilization percentages of departure and arrival flight tracks, respectively, for Build Alternative

9 IMPACT POTENTIAL The following sections present the noise exposure contours for the No-Action Alternative and Build Alternatives 3 and 4, as developed from the information described in Section The potential for impact was identified in four ways: 1) analysis of noise exposure contours, 2) noise levels at specific noise-sensitive receptors within the contours, 3) noise levels for affected land use, and 4) number of housing units and population exposed to various noise levels. FAA Orders E and A establish the Threshold of Significance for noise impacts to be a 1.5 DNL or greater increase in noise at any noise-sensitive areas within the 65 DNL contour (DOT, FAA, 1985, 2004). FAA Order E considers that if an increase in the DNL of 1.5 dba occurs at any noise-sensitive area within the 65 DNL contour, further analysis is warranted. To comply with FAA s guidance provided in E and the recommendations of the 1992 FICON, noise-sensitive areas between 60 and 65 DNL should be evaluated for increases of 3.0 DNL or greater if an increase of 1.5 DNL occurs at any noise-sensitive area within the 65 DNL. To comply with guidance provided in FAA Order E, for proposed air traffic actions above 3,000 feet AGL, potential noise impacts resulting from changes in airport arrivals and departures should be disclosed. Noise-sensitive areas between 45 and 60 DNL should be evaluated for increases of 5.0 DNL or greater. Noise-sensitive receptors, including schools, churches, day care centers, historic sites, parks, and recreation areas were identified using a Geographic Information Systems (GIS) database. Using the INM, the exposure from aircraft noise was calculated at these specific noise-sensitive receptors. The specific points were selected to represent noise-sensitive land use areas in close proximity to the airport that could be potentially located within the 60 DNL noise exposure area of a Build Alternative. The specific points are shown on Figure These noise-sensitive sites were evaluated in accordance with FAA Order E and the 1992 FICON recommendations, as described below: 1. Sites included in the 65 DNL contour of the Build Alternatives, if they are projected to receive increased noise levels of 1.5 dba or more, relative to the No-Action Alternative. Sites newly included in the 65 DNL contour of the Build Alternatives that are projected to receive increased noise levels of 1.5 dba or more, relative to the No-Action Alternative, are included in this analysis. 2. If sites identified in item (1) occur, the analysis will be expanded to include noise-sensitive areas within the 60 DNL contour that would experience an increase of 3.0 dba or more with the Build Alternatives, relative to the No-Action Alternative. In accordance with FAA Order E and the 1992 FICON recommendations, it is FAA policy that mitigation should be considered for areas that exceed the DNL 1.5 dba Threshold of Significance and the DNL 3.0 dba increase noted above (DOT, FAA, 2004; FICON, 1992). Mitigation is not warranted for noise-sensitive areas that exceed the 5.0 DNL increase between 45 and 60 DNL. A discussion of land use and population within the 65 DNL contour is contained in Section 5.2, Land Use, of this DEIS. Section presents a discussion of noise exposure in terms of metrics other than DNL. 5-11

10 No-Action Alternative Noise exposure resulting from year 2010 operations (without any new runways) is depicted as contours of 65 DNL, 70 DNL, and 75 DNL, as shown on Figure DNL contours are a graphical representation of how the noise from IAD s annual average daily aircraft operations is distributed over the surrounding area. The estimated land area within each DNL contour interval is shown in Table Of the slightly over 5,100 acres of land exposed to DNL of 65 dba or greater, approximately 4,873 acres would be within the airport property. Off-airport acreage within the 65 DNL contour would total approximately 233 acres, all of which would be exposed to DNL between 65 dba and 70 dba. TABLE ESTIMATED LAND AREA WITHIN 2010 NO-ACTION ALTERNATIVE DNL CONTOURS Land Area (acres) Off-Airport Contour Interval On-Airport Fairfax Loudoun Grand County County Total Total , , , , , ,106.4 Total 4, ,106.2 Source: URS Corporation, Table includes values of DNL for each of the representative noise-sensitive receptors (shown in Figure ) in the vicinity of IAD for the 2010 No-Action Alternative. The No-Action Alternative would not result in significant impact to any of the individual noise-sensitive receptors, since noise levels are less than 65 DNL at all noise-sensitive receptors. FAA defines 65 DNL as the threshold of noise compatibility with residential land uses (FAA, 1995). Because no residential land use would be within the 65 DNL contour for the No-Action Alternative, there would be no residential population exposed to 65 DNL or greater. A detailed discussion of land use within the 65 DNL contour is contained in Section 5.2, Land Use in this DEIS Build Alternative 3 Noise exposure resulting from Year 2010 operations for Build Alternative 3 is depicted as contours of 65 DNL, 70 DNL, and 75 DNL and are shown in Figure The estimated land area within each DNL contour interval is shown in Table Of the approximately 5,926 acres of land exposed to DNL of 65 dba or greater, approximately 5,720 acres would be within the airport property. Off-airport acreage within the 65 DNL contour would total approximately 206 acres, all of which would be exposed to DNL between 65 dba and 70 dba. 5-12

11 TABLE DNL VALUES AT NOISE-SENSITIVE RECEPTORS FOR THE NO-ACTION ALTERNATIVE Receptor ID Receptor Name No-Action DNL (dba) C1 Pleasant Valley United Methodist Church 60.3 C2 Second Shiloh Church 55.3 C3 Church 57.0 C4 Heritage Baptist Church 44.9 C5 Christian Fellowship 62.6 C6 Guilford Baptist Church 49.6 C7 Oakton Baptist Church 62.2 C8 Oakton Baptist Church 60.6 C9 Chantilly Wesleyan Church 54.6 C10 Ox Hill Baptist Church 53.5 C11 Chantilly Baptist Church 60.8 C12 Arcola United Methodist Church 60.0 S1 Guilford Elementary School 42.6 S2 Ashburn Elementary School 46.8 S3 Dominion Trail Elementary School 48.4 S4 Arcola Elementary School 54.4 S5 Broad Run High School 45.9 S6 Little River Elementary School 58.1 S7 Westfield High School 56.4 S8 Hutchison Farms Elementary School 55.5 S9 Farmwell Station Middle School 50.5 S10 Bethesda Country Day School 56.3 S11 Chesterbrook Academy 56.1 S12 Stone Ridge Middle School 55.4 S13 Legacy Elementary School 55.4 S14 Mercer Middle School 55.5 S15 Rachel Carson Middle School 55.0 S16 Franklin Middle School 50.8 D1 Day Care 56.2 D2 Day Care 45.5 D3 Day Care 52.9 D4 Day Care 45.5 D5 Day Care 49.2 D6 Day Care 47.4 D7 Creative Adventures Preschool and Dance Academy 63.0 D8 Little Scientist Enrichment Center 60.2 D9 Chantilly Academy Gymnastics & Preschool 61.0 O1 Sully Plantation 60.6 O2 Pleasant Valley Subdivision/Community Park 59.0 O3 Frying Pan Park/Kidwell Farms 46.6 O4 Arcola Community Center 58.0 O5 Arcola Slave Quarters 59.4 O6 Sterling Annex Community Center 56.2 O7 Flatlick Stream Valley Park 56.8 O8 NOAA/NWS Sterling Research and Development Center 49.1 Source: URS Corporation,

12 TABLE ESTIMATED LAND AREA WITHIN 2010 BUILD ALTERNATIVE 3 DNL CONTOURS Land Area (acres) Off-Airport Contour Interval On-Airport* Fairfax Loudoun Grand County County Total Total , , , , , ,289.1 Total 5, ,926.2 Note: *On-Airport Land Area includes land to be acquired for construction of Build Alternative 3. Source: URS Corporation, Table includes values of DNL for each of the representative noise-sensitive receptors (shown on Figure ) in the vicinity of IAD for the 2010 Build Alternative 3 compared to the No-Action Alternative. Build Alternative 3 would not result in significant impact to any of the individual noisesensitive receptors, since noise levels are less than 65 DNL at all noise-sensitive receptors. FAA defines 65 DNL as the threshold of noise compatibility with residential land uses (FAA, 1995). Because no residential land use would be within the 65 DNL contour for Build Alternative 3, there would be no residential population exposed to 65 DNL or greater. A detailed discussion of land use within the 65 DNL contour is contained in Section 5.2, Land Use, of this DEIS. Section presents a discussion of noise exposure in terms of metrics other than DNL. For the purposes of fully disclosing potential effects of Build Alternative 3, difference contours were generated to identify noise-sensitive areas that would be exposed to increases of 3.0 db or greater between the 60 and 65 DNL, and 5.0 db or greater between the 45 and 60 DNL. Figure illustrates the noise-sensitive area that would be exposed to increases of 3.0 db or greater between the 60 and 65 DNL with Build Alternative 3. Table identifies the number of acres of residential land use, number of residential parcels, and estimated population that would be exposed to increases of 3.0 db or greater between the 60 and 65 DNL with Build Alternative 3. Appendix D-10 contains information regarding areas that would be exposed to increases of 5.0 db or greater between the 45 and 60 DNL with Build Alternative

13 TABLE DNL VALUES AT NOISE-SENSITIVE RECEPTORS FOR BUILD ALTERNATIVE 3 Receptor ID Build Alternative 3 DNL (dba) No-Action Receptor Name DNL (dba) C1 Pleasant Valley United Methodist Church C2 Second Shiloh Church C3 Church C4 Heritage Baptist Church C5 Christian Fellowship C6 Guilford Baptist Church C7 Oakton Baptist Church C8 Oakton Baptist Church C9 Chantilly Wesleyan Church C10 Ox Hill Baptist Church C11 Chantilly Baptist Church C12 Arcola United Methodist Church S1 Guilford Elementary School S2 Ashburn Elementary School S3 Dominion Trail Elementary School S4 Arcola Elementary School S5 Broad Run High School S6 Little River Elementary School S7 Westfield High School S8 Hutchison Farms Elementary School S9 Farmwell Station Middle School S10 Bethesda Country Day School S11 Chesterbrook Academy S12 Stone Ridge Middle School S13 Legacy Elementary School S14 Mercer Middle School S15 Rachel Carson Middle School S16 Franklin Middle School D1 Day Care D2 Day Care D3 Day Care D4 Day Care D5 Day Care D6 Day Care D7 Creative Adventures Preschool and Dance Academy D8 Little Scientist Enrichment Center D9 Chantilly Academy Gymnastics & Preschool O1 Sully Plantation O2 Pleasant Valley Subdivision/Community Park O3 Frying Pan Park/Kidwell Farms O4 Arcola Community Center O5 Arcola Slave Quarters O6 Sterling Annex Community Center O7 Flatlick Stream Valley Park O8 NOAA/NWS Sterling Research and Development Center Source: URS Corporation, Difference DNL (dba) 5-19

14 TABLE NOISE-SENSITIVE LAND USES EXPOSED TO 3+ db INCREASES BETWEEN 60 AND 65 DNL FOR BUILD ALTERNATIVE 3 Contour Interval Residential Land Use (acres) Number of Residential Parcels Estimated Population Although increases of 3 DNL or greater between 60 and 65 DNL, as well as increases of 5 DNL or greater between 45 and 60 DNL do not exceed FAA s Threshold of Significance for noise impacts, both FAA and MWAA acknowledge that people may be adversely affected by these increases in aircraft noise levels associated with Build Alternative Build Alternative 4 Noise exposure resulting from Year 2010 operations for Build Alternative 4 is depicted as contours of 65 DNL, 70 DNL, and 75 DNL as shown on Figure DNL contours are a graphical representation of how the noise from IAD s annual average daily aircraft operations is distributed over the surrounding area. The estimated land area within each DNL contour interval is shown in Table Of the slightly over 5,900 acres of land exposed to DNL of 65 dba or greater, approximately 5,687 acres would be within the airport property. Off-airport acreage within the 65 DNL contour would total approximately 216 acres, all of which would be exposed to DNL between 65 dba and 70 dba. TABLE ESTIMATED LAND AREA WITHIN 2010 BUILD ALTERNATIVE 4 DNL CONTOURS Land Area (acres) Off-Airport Contour Interval On-Airport* Fairfax County Loudoun County Total Grand Total , , , , , ,286.9 Total 5, ,902.9 Note: *On-Airport Land Area includes land to be acquired for construction of Build Alternative 4. Source: URS Corporation, Table includes values of DNL for each of the representative noise-sensitive receptors (shown on Figure ) in the vicinity of IAD for the 2010 Build Alternative 4 compared to the No-Action Alternative. Build Alternative 4 would not result in significant impact to any of the individual noise-sensitive receptors, since noise levels are less than 65 DNL at all noise-sensitive receptors. 5-20

15 Receptor ID TABLE DNL VALUES AT NOISE-SENSITIVE RECEPTORS FOR BUILD ALTERNATIVE 4 Build Alternative 4 DNL (dba) No-Action Receptor Name DNL (dba) C1 Pleasant Valley United Methodist Church C2 Second Shiloh Church C3 Church C4 Heritage Baptist Church C5 Christian Fellowship C6 Guilford Baptist Church C7 Oakton Baptist Church C8 Oakton Baptist Church C9 Chantilly Wesleyan Church C10 Ox Hill Baptist Church C11 Chantilly Baptist Church C12 Arcola United Methodist Church S1 Guilford Elementary School S2 Ashburn Elementary School S3 Dominion Trail Elementary School S4 Arcola Elementary School S5 Broad Run High School S6 Little River Elementary School S7 Westfield High School S8 Hutchison Farms Elementary School S9 Farmwell Station Middle School S10 Bethesda Country Day School S11 Chesterbrook Academy S12 Stone Ridge Middle School S13 Legacy Elementary School S14 Mercer Middle School S15 Rachel Carson Middle School S16 Franklin Middle School D1 Day Care D2 Day Care D3 Day Care D4 Day Care D5 Day Care D6 Day Care D7 Creative Adventures Preschool and Dance Academy D8 Little Scientist Enrichment Center D9 Chantilly Academy Gymnastics and Preschool O1 Sully Plantation O2 Pleasant Valley Subdivision/Community Park O3 Frying Pan Park/Kidwell Farms O4 Arcola Community Center O5 Arcola Slave Quarters O6 Sterling Annex Community Center O7 Flatlick Stream Valley Park O8 NOAA/NWS Sterling Research and Development Center Source: URS Corporation, Difference DNL (dba) 5-22

16 FAA defines 65 DNL as the threshold of noise compatibility with residential land uses (FAA, 1995). Because no residential land use would be within the 65 DNL contour for Build Alternative 4, there would be no residential population exposed to 65 DNL or greater. A detailed discussion of land use within the 65 DNL contour is contained in Section 5.2, Land Use, of this DEIS. Section presents a discussion of noise exposure in terms of metrics other than DNL. For the purposes of fully disclosing potential effects of Build Alternative 4, difference contours were generated to identify noise-sensitive areas that would be exposed to increases of 3.0 db or greater between the 60 and 65 DNL, and 5.0 db or greater between the 45 and 60 DNL. Figure illustrates the noise-sensitive area that would be exposed to increases of 3.0 db or greater between the 60 and 65 DNL with Build Alternative 4. Table identifies the number of acres of residential land use, number of residential parcels, and estimated population that would be exposed to increases of 3.0 db or greater between the 60 and 65 DNL with Build Alternative 4. Appendix D-10 contains information regarding areas that would be exposed to increases of 5.0 db or greater between the 45 and 60 DNL with Build Alternative 4. TABLE NOISE-SENSITIVE LAND USES EXPOSED TO 3+ db INCREASES BETWEEN 60 AND 65 DNL FOR BUILD ALTERNATIVE 4 Contour Interval Residential Land Use (acres) Number of Residential Parcels Estimated Population Although increases of 3 DNL or greater between 60 and 65 DNL, as well as increases of 5 DNL or greater between 45 and 60 DNL do not exceed FAA s Threshold of Significance for noise impacts, both FAA and MWAA acknowledge that people may be adversely affected by these increases in aircraft noise levels associated with Build Alternative SUPPLEMENTAL NOISE METRIC ANALYSIS The FICON report, Federal Agency Review of Selected Airport Noise Analysis Issues, dated August 1992, concluded that the DNL is the recommended metric and should continue to be used as the primary metric for aircraft noise exposure. However, DNL analysis may optionally be supplemented on a case-bycase basis to characterize specific noise effects. The type and nature of activity potentially impacted should be considered. The FICON report identified sleep disturbance and speech interference as two areas where it is appropriate to consider supplemental metrics (FAA, 2004). 5-23

17 This analysis was proposed to determine whether or not these phenomena might occur and, if so, how frequently such interference/disturbance could potentially occur on an average daily/nightly basis. The supplemental metrics Maximum Sound Level (L max ), Time Above (TA), and Number-of-events Above (NA) provide information about the number, level, and duration of the aircraft noise events that comprise the average daily noise exposure expressed by the DNL metric. The frequency of occurrence is described by contours of the number of events that would exceed the selected interference/disturbance threshold, known as NA contours. There are no established criteria for noise exposure measured by the L max, TA, or NA metrics. They are used to supplement DNL analysis. DNL is the only aviation noise metric with a widely established and accepted criterion for determining which project alternatives, if implemented without mitigation, would result in significant impact. As used in this analysis, these metrics help communicate noise exposure in terms that help the public better understand the DNL metric and what metric is used in determining if a proposed action will have a significant noise impact. The L max analysis shown in Appendix D-11, Table D-11.1 identifies the loudest maximum instantaneous sound level modeled for each noise-sensitive receptor point, shown on Figure It does not reveal if more than one event at this level is predicted to occur at these receptor points. The purpose of the analysis with the L max metric is to identify the loudest predicted event at each receptor point. The L max analysis indicates there will be a slight increase relative to the No-Action Alternative in the predicted L max at most receptor sites under either Build Alternative. No increase in L max is predicted at two receptor points for Build Alternative 3 and at ten receptor points for Build Alternative 4. A decrease in L max is predicted at three receptor points for Build Alternative 4. For Build Alternative 3, increases between 0.1 and 2.0 dba are predicted for 31 of the 45 receptors while Build Alternative 4 is predicted to have 26 of the 45 receptors increase between 0.1 and 2.0 dba. Six receptors would have increases between 2.1 and 4.0 dba for Build Alternative 3 and two receptors for Build Alternative 4. Increases between 4.1 and 8.1 dba are predicted for six sites in Build Alternative 3 and four sites for Build Alternative 4. Appendix D-11, Table D-11.2 compares values of TA70 for each of the individual noise-sensitive receptors (shown on Figure ) in the vicinity of IAD for each alternative. Of the 45 receptor points analyzed in Appendix D-11, Table D-11.2, the TA 70 would decrease relative to the No-Action Alternative at 23 of the points and increase at 20 points if either Build Alternative is implemented. The average TA70 increase at the 20 points, considering both Build Alternatives, is 2.0 minutes and the average TA70 decrease at the 23 points is 2.4 minutes. The average change at all 45 points if Build Alternative 3 is implemented is 0.3 minutes (4.9 percent decrease based on 6.1 minute average in the No-Action Alternative) and 0.4 minutes if Build Alternative 4 is implemented (6.6 percent decrease based on 6.1 minute average in the No-Action Alternative). There is little difference between the TA70 values for each receptor point when comparing the Build Alternatives. At 34 out of the 45 points, there is no difference between the Build Alternatives. Only 4 points differ by over one minute between the Build Alternatives, so the TA70 variation between the Build Alternatives is only a fraction of a percent, and only varies by 1.2 to 1.9 percent at 4 out of the 45 receptor points. 5-25

18 In this case, the TA70 analysis helps confirm there is no significant increase in noise exposure among any of the modeled Build Alternatives relative to the No-Action Alternative. DNL is the average noise level (weighted for nighttime events) for the average annual day. TA70 communicates how many minutes out of the 900 minutes in the daytime hours (7:00 a.m. to 10:00 p.m.) that aircraft noise exceeds the selected threshold level of 70 db, which for the No-Action Alternative is about 1 percent of the time. NA contours for a criterion level of 70 dba (L max ) were generated for purposes of assessing the potential for indoor speech interference. As discussed in Appendix D-11, an outdoor L max of 70 dba pertains to an indoor sentence intelligibility of 99.9 percent. Appendix D-11, Figures D-11.2 through D-11.4 illustrate contours of daytime events at or above 70 dba Outdoor L max (NA70) for the No-Action Alternative and Build Alternatives 3 and 4, respectively. Appendix D-11, Table D-11.3 compares the NA70 at each of the individual noise-sensitive receptors (shown on Figure ) in the vicinity of IAD for the No-Action Alternative and Build Alternatives 3 and 4. The results are presented in ranges of numbers of events, i.e., less than 15 events, 15 to 29 events, 30 to 59 events, 60 to 119 events, and 120 events or greater. Of the 45 receptor points analyzed in Appendix D-11, Table D-11.3, the NA70 would remain the same relative to the No-Action Alternative at 18 of the points if either Build Alternative is implemented. The NA70 would decrease at 13 of the points and increase at 14 points if either Build Alternative is implemented. Two sites would experience 120 or more daytime events at or above 70 dba Outdoor L max (NA70) if either Build Alternative is implemented. Christian Fellowship Church would experience 120 or more events for the No-Action Alternative and Build Alternatives 3 and 4. Sully Plantation would experience an increase from 60 to 119 events to 120 events or greater if either Build Alternative is implemented. Nighttime NA contours for a criterion level of 90 dba (sound exposure level [SEL]) were generated for purposes of assessing the potential for indoor sleep disturbance. As discussed in Appendix D-11, an outdoor SEL of 90 dba correlates to an indoor maximum percent awakening of less than 10 percent. Appendix D-11, Figures D-11.6 through D-11.8 illustrate contours of nighttime events at or above 90 dba outdoor SEL (NA90) for the No-Action Alternative and Build Alternatives 3 and 4, respectively. The contours for all three alternatives are identical, since the nighttime number of operations, runway use, and flight track use are the same for each of the three alternatives. Therefore, neither of the Build Alternatives would result in an increase in potential incidents for sleep disturbance when compared to the No-Action Alternative NON-AVIATION-RELATED NOISE There are no improvements to local roads, highways, or railroads associated with the Build Alternatives that would not also occur under the No-Action Alternative. Therefore, the Build Alternatives would not result in non-aviation-related noise impacts when compared to the No-Action Alternative. Increased noise from construction vehicles is expected as a result of constructing either Build Alternative. These impacts would be temporary and would be minimized through the establishment and use of environmental controls, such as Best Management Practices (BMPs), and Federal, state, and local construction mitigation guidelines. Construction noise impacts are discussed in Section

19 5.1.6 MITIGATION MEASURES It is FAA policy that mitigation should be provided for noise-sensitive areas that exceed the 1.5 DNL Threshold of Significance within the 65 DNL. No residences or noise-sensitive receptors in Loudoun or Fairfax County would exceed the 1.5 DNL Threshold of Significance within the 65 DNL. Therefore, no mitigation is required. It is FAA policy that mitigation should be considered for noise-sensitive areas that exceed the 3.0 DNL increase between 60 and 65 DNL. Fifteen residential parcels in Loudoun County would experience increases greater than 3.0 dba between the 60 and 65 DNL, relative to the No-Action Alternative. No residences in Fairfax County or any noise-sensitive receptors in Loudon or Fairfax County would exceed the 3.0 DNL criteria between the 60 and 65 DNL. Therefore, mitigation could be considered for the fifteen residential parcels in Loudon County. It is FAA policy that mitigation is not warranted for noise-sensitive areas that exceed the 5.0 DNL increase between 45 and 60 DNL. Potential mitigation measures are discussed in Section of this DEIS. 5.2 LAND USE OVERVIEW OF IMPACTS No property acquisitions would be required for the No-Action Alternative. The No-Action Alternative year DNL contour covers a total of 5,106.2 acres of which 95.4 percent is located over IAD. The remaining 4.6 percent consists of acres of land that is being used for commercial, industrial, office, governmental, or agricultural purposes or is vacant. All of these land uses are compatible with aircraft noise levels. There are no noise-sensitive receptors located within the 65 DNL contour. Fairfax and Loudoun counties recognize the importance of IAD to their local economy and support the airport s expansion in their Comprehensive Plans and land use ordinances; therefore, the No-Action Alternative is inconsistent with land use policies of both counties. Although most of the development would occur on existing airport property, both Build Alternatives would result in off-airport land use impacts. For Build Alternative 3, a combined total of 448 acres would be acquired for construction and buffer purposes. This area consists of 40 acres of the NOAA/NWS Sterling property, a 95.9-acre sod farm, and portions of 3 tracts owned by corporations. No residential properties would be acquired. The year DNL contour for Build Alternative 3 covers 5,926.2 acres of which nearly 96.5 percent is located over IAD. The remaining 3.5 percent consists of acres that predominantly is being used for commercial, industrial, governmental, or agricultural purposes or is vacant. Build Alternative 3 is consistent with land use policies of Fairfax and Loudoun counties. 5-27