Page 13 - Winter 2009

Table 2. Daytime Measurement Results
Measurement Number
Total Noise
MSP
Non -Airport
Noise
Measured Non -Airport
Noise
Difference in non -airport noise
L90
Measured Non-airport noise minus
L90
3112
61.5
56.9
53.7
3.2
50.9
2.8
3116
62.3
49.9
43.6
6.3
39.1
4.5
3117
67.9
53.9
46.9
7.0
45.2
1.7
3118
66.1
54.7
50.8
3.9
45.9
4.9
3119
62.9
52.7
51.6
1.1
45.1
6.5
3120
61.8
51.2
47.0
4.2
44.5
2.5
3121
63.3
56.9
52.1
4.8
49.4
2.7
3211
56.4
54.6
51.5
3.1
48.5
3.0
3214
64.9
56.1
48.0
8.1
46
2.0
3215
63.6
53.7
52.7
1.0
49.6
3.1
4151
55.8
53.3
46.3
7.0
43.9
2.4
4152
57.4
53.7
53.5
0.2
42.4
11.1
4153
59.0
51.7
49.2
2.5
48.2
1.0
4154
56.9
52.0
52.0
0.0
44.8
7.2
4155
58.6
49.6
46.7
2.9
43.5
3.2
4156
66.1
52.3
46.9
5.4
41.8
5.1
4157
54.9
54.4
50.4
4.0
48.7
1.7
4158
56.7
51.8
46.0
5.8
42.8
3.2
Average
60.9
53.3
49.4
3.9
45.6
3.8
STDEV
4.0
2.1
3.0
2.4
3.1
2.5
This table shows our total measured noise, “MSP calculated” non-Airport noise, the actual measured non-Airport noise, and the difference between the two (dB). This table also shows the L90 and the difference between the measured MSP non- Airport noise and the L90.
to show that the monitored results that we developed with our sampling methodology were much more valid predic- tions of the community noise than the “community levels” measured by the airport’s noise monitoring system.
(3) Quantify the impacts
The three impacts quantified were annoyance, speech interference, and sleep disturbance. Our noise criterion level for “quietude” was a DNL in the range of 50–55 dB. Our speech interference criterion was an indoor Leq less than 45 dB for indoor communication and a similar level for outdoor communication. Our sleep disturbance criterion was a single event level (SEL) greater than 50 dB. There was not great contention in the lawsuit on the
speech interference criterion or the
methodology and levels of sleep dis-
turbance. For sleep disturbance, the
methods of the new ANSI/ASA S12.9
Part 6 were used1 by all parties to the
lawsuit. (Details of the sleep distur-
bance methodology can be found in
the July 2009 issue of Acoustics Today.)
The most contentious issue was the annoyance criteria. Airports and the Federal Aviation Administration
ignoring annoyance and ignoring the outdoor level. They were not sustained by the court in this attempt.
The conclusions on this point are clear. The EPA criteria are jointly outdoors and indoors. Moreover the primary cri- terion is 55 dB outdoors since the 45 dB indoor criterion pro- tects only speech communication and in no way protects from sleep disturbance, and in no way establishes a level for indoor noise annoyance.
The next point was to show that the annoyance from air- port noise in the 60–65 DNL zone is not low or insignificant. Here again it was necessary to show that the criteria present- ed by MSP were biased and misleading. The FAA uses a pre- diction curve (Fig. 6) for the percent “highly annoyed” versus
(FAA) have relied on a 45 dB indoor criterion citing the Environmental Protection Agency (EPA) as their source. However, we felt that the Airport (and the FAA) were misinterpret-
2
ing the EPA document. Specifically they cited the 1974 EPA “Levels Document” which established “levels of environ- mental noise requisite to protect health and welfare with an ade- quate margin of safety.” That doc- ument establishes indoor and outdoor noise criteria used by most federal agencies. It clearly states that the indoor criterion, 45 dB, is necessary and sufficient for protecting speech communi- cation. The EPA presents indoor and outdoor numbers as a pair using the conjunction “and” in several places. Never do they use the conjunction “or.” Examples citing this pair of criteria can be found on page 22 of the “Levels Document,” on page D-34, and page D-36. It is the 55 dB outdoor criterion that protects from annoyance and the 45 dB indoor criterion that protects just indoor speech communication. But MSP sought to establish just the 45 dB indoor criterion as sufficient,
Table 3. Nighttime Measurement Results
Site
4849 13th Ave. S
4525 Pillsbury S
4525 Pillsbury S
300 Elmwood Pl.
300 Elmwood Pl.
Date
20 June 2006
20 June 2006
21 June 2006
20 June 2006
21 June 2006
Non-Airport/ Community LEQ(dB)
39.4
43.4/37.9
39.3
39.7
35.8
Total LEQ (dB)
50.0
50.0
48.5
49.0
48.1
Difference (dB)
10.6
6.6
9.2
9.3
16.3
12 Acoustics Today, October 2009