MEMORANDUM
The Aurora State Airport (ASA) DECIBEL Committee recommended three separate noise mitigation measures for the years 2007 and 2017. With the direction of the Oregon Department of Aviation (ODA), Harris Miller Miller & Hanson Inc (HMMH) completed the evaluations of these measures. This memorandum summarizes the results of this noise mitigation modeling and serves as the Statement of Work deliverable for a brief summary report.
NOISE MITIGATION MODELING
DESCRIPTION
This study used the Federal Aviation Administration’s (FAA) Integrated Noise Model (INM) to prepare noise contours for annual aircraft exposure, in terms of the Day-Night Average Sound Level (DNL). As in our previous modeling, HMMH used INM version 6.0c for this study. The inputs to the INM for forecast years 2007 and 2017 remained the same as in the base cases except as noted in each case description that follows. For each separate case and forecast year, HMMH developed DNL noise contours, made estimates of current housing units within the DNL contour intervals, and made comparisons of the modeled DNL values at four residential sites. Table 1 lists these sites, which correspond to the previous location of our residential noise measurement sites.
Table 1. Residential Site Locations for DNL
Comparison
|
Site
No. |
Location |
|
3 |
32575
SW Riviera Lane – Charbonneau Community |
|
4 |
14635
Kasel Court – Aurora Community |
|
5 |
Summer
- 21320 Main Street – Aurora Community |
|
Winter
- 21331 Main Street – Aurora Community |
|
|
6 |
22037
Carissa Avenue – Deer Creek Community |
Case 1 – Change Preferential
Runway from Runway 17 to Runway 35
The ODA obtained archived weather information for the past year and, in conjunction with the DECIBEL Committee, determined the runway use percentages of 20% for Runway 17 and 80% for Runway 35. Table 2 shows the runway use for the Base Case and for Case 1. The Base Case had used 90% for Runway 17 and 10% for Runway 35 when Runway 17 was modeled as the preferential runway. Therefore, HMMH changed the modeled runway use percentages for all fixed-wing aircraft operations to reflect the 20/80 split, which meant 80% of arrivals, departures, and traffic patterns were flown to/from Runway 35. All other INM inputs remained the same.
Table 2. Runway Use Change from Base Case
|
Case |
Runway 17 |
Runway 35 |
|
Base |
90% |
10% |
|
Case
1 |
20% |
80% |
Case 2 – Change Runway 17 Left Traffic Pattern to Right Traffic Pattern
HMMH changed the INM modeled traffic pattern for Runway 17 from a left traffic pattern with tracks to the east of ASA to a right traffic pattern with tracks to the west of ASA. The new traffic pattern flight tracks mirror the existing left traffic pattern flight tracks and are shown in Figure 1. HMMH redistributed all flight operations using the left traffic pattern to the comparable right traffic pattern flight tracks. In addition, flight arrivals that entered the traffic pattern were altered to accommodate the right traffic pattern. All other INM inputs remained unchanged.
Case 3 – Delete Left Turn
Departure from Runway 17
HMMH redistributed all modeled flight departure operations from Runway 17 that used the left-turn-after-takeoff departure to the other two modeled departure flight tracks—climb runway heading and climbing right turn. Table 3 shows the changes to affected flight track utilization rates from the Base Case to Case 3. All other INM inputs remained the same.
Table 3. Change in Flight Track Utilization Rates
from Base Case
|
Aircraft Categories and
Operations |
Base Case |
Case 3 |
||
|
Runway 17 |
Runway 17 |
|||
|
Track |
Use (%) |
Track |
Use (%) |
|
|
Non-Jet Departures (fixed-wing) |
17D1 |
25% |
17D1 |
70% |
|
17D2 |
25% |
17D2 |
30% |
|
|
17D3 |
50% |
17D3 |
0% |
|
|
Note: All other utilization rates remained the
same. |
||||
Figure 1. Case
2 Modeled Flight Tracks
NOISE EXPOSURE CONTOURS
For comparison purposes, the unmitigated (base case) DNL noise exposure contours for years 2007 and 2017 are included in the Appendix as Figures A1 and A2, respectively. For each case evaluated, Table 4 compares the DNL at the various site locations with the base case DNL values.
Table
4. Comparison of Unmitigated and Case
Specific DNL
Source: INM
6.0c, HMMH
|
Year |
Site |
Base Case |
Case 1 |
Case 2 |
Case 3 |
|||
|
DNL (dB) |
DNL (dB) |
Delta (dB) |
DNL (dB) |
Delta (dB) |
DNL (dB) |
Delta (dB) |
||
|
2007 |
Charbonneau |
49.7 |
48.1 |
-1.6 |
49.7 |
0.0 |
49.7 |
0.0 |
|
North Aurora |
55.5 |
51.6 |
-3.9 |
54.0 |
-1.5 |
54.5 |
-1.0 |
|
|
Central Aurora |
53.8 |
47.8 |
-6.0 |
51.3 |
-2.5 |
51.9 |
-1.9 |
|
|
Deer Creek |
57.6 |
56.2 |
-1.4 |
58.5 |
0.9 |
58.1 |
0.5 |
|
|
2017 |
Charbonneau |
50.1 |
48.5 |
-1.6 |
50.1 |
0.0 |
50.1 |
0.0 |
|
North Aurora |
55.9 |
52.0 |
-3.9 |
54.4 |
-1.5 |
54.9 |
-1.0 |
|
|
Central Aurora |
54.2 |
48.2 |
-6.0 |
51.7 |
-2.5 |
52.3 |
-1.9 |
|
|
Deer Creek |
58.1 |
56.6 |
-1.5 |
58.9 |
0.8 |
58.5 |
0.4 |
|
Case 1
Figures 2 and 3 show the modeled DNL noise exposure contours for the forecast years 2007 and 2017. In this case, the majority of departures, generally the loudest flight phase, switch to Runway 35 and the left traffic pattern for Runway 35 becomes the primary traffic pattern. Thus, as shown in Table 4, changing the preferential runway use reduces the noise exposure to the south and east of ASA and increases the noise exposure more noticeably to the northwest. The reduction at the Charbonneau site can be explained by the decline in approaches or arrivals to Runway 17, the flight operation having the most affect on this location.
HMMH estimated the housing unit counts within the DNL contour intervals for Case 1 using the aerial photo provided by ODA and compared those with the base forecast years’ data in Table 5.
Table 5. Estimated Housing
Units within DNL Contour Intervals for Case 1
Source: ODA Aerial Photo, 19 October 1998
|
Year/Case |
55-60 dB DNL |
60-65 dB DNL |
65-70 dB DNL |
70-75 dB DNL |
Total (within 55 dB DNL) |
|
2007/Base |
150 |
141 |
25* |
0 |
316 |
|
2007/Case 1 |
128 |
49 |
19* |
0 |
196 |
|
2017/Base |
195 |
146 |
37* |
0 |
378 |
|
2017/Case 1 |
150 |
52 |
22* |
0 |
224 |
* Note: Incompatible land use according to FAA
Guidelines
Figure 2. Case
1 Modeled DNL Noise Exposure Contours for Year 2007
Figure 3. Case
1 Modeled DNL Noise Exposure Contours for Year 2017
Case 2
Figures 4 and 5 show the modeled DNL noise exposure contours for Case 2 in the forecast years 2007 and 2017. In this case, with the right traffic pattern for Runway 17, all local traffic pattern operations are now to the west of the airport thereby increasing the noise exposure to the west and southwest while reducing the noise exposure to the east and southeast. Thus, as shown in Table 4, changing the direction of the Runway 17 traffic pattern reduces the noise exposure to the east and southeast of ASA over the city of Aurora and increases the noise exposure over the housing developments to the west and southwest of ASA. The Charbonneau site is unaffected by the change in direction of the Runway 17 traffic pattern.
HMMH estimated the housing unit counts within the DNL contour intervals for Case 2 using the aerial photo provided by ODA and compared those with the base forecast years’ data in Table 6.
Table 6. Estimated Housing
Units within DNL Contour Intervals for Case 2
Source: ODA Aerial Photo, 19 October 1998
|
Year/Case |
55-60 dB DNL |
60-65 dB DNL |
65-70 dB DNL |
70-75 dB DNL |
Total (within 55 dB DNL) |
|
2007/Base |
150 |
141 |
25* |
0 |
316 |
|
2007/Case 2 |
169 |
149 |
25* |
0 |
343 |
|
2017/Base |
195 |
146 |
37* |
0 |
378 |
|
2017/Case 2 |
186 |
165 |
32* |
0 |
383 |
* Note: Incompatible land use according to FAA
Guidelines
Figure 4. Case 2 Modeled DNL Noise Exposure Contours
for Year 2007
Figure 5. Case 2 Modeled DNL Noise Exposure Contours
for Year 2017
Case 3
Figures 6 and 7 show the modeled DNL noise exposure contours for the forecast years 2007 and 2017. All Runway 17 departures either climb out on runway heading and turn left after passing the City of Aurora or initiate a climbing right turn to the west and northwest. As Table 4 shows, the effect is to reduce the noise exposure to the City of Aurora environs and slightly increase the noise exposure to the west. The Charbonneau site is unaffected by the change in departure flight track utilization of Runway 17.
HMMH estimated the housing unit counts within the DNL contour intervals for Case 3 using the aerial photo provided by ODA and compared those with the base forecast years’ data in Table 7.
Table 7. Estimated Housing
Units within DNL Contour Intervals for Case 3
Source: ODA Aerial Photo, 19 October 1998
|
Year/Case |
55-60 dB DNL |
60-65 dB DNL |
65-70 dB DNL |
70-75 dB DNL |
Total (within 55 dB DNL) |
|
2007/Base |
150 |
141 |
25* |
0 |
316 |
|
2007/Case 3 |
134 |
142 |
32* |
0 |
308 |
|
2017/Base |
195 |
146 |
37* |
0 |
378 |
|
2017/Case 3 |
183 |
134 |
50* |
0 |
367 |
* Note: Incompatible land
use according to FAA Guidelines
Figure 6. Case 3 Modeled DNL Noise Exposure Contours
for Year 2007
Figure 7. Case 3 Modeled DNL Noise Exposure Contours
for Year 2017
APPENDIX
Figure A1. Base
Case Forecast 2007 DNL Noise Exposure Contours
Figure A2. Base Case Forecast 2017 DNL Noise Exposure
Contours
