STATE OF WASHINGTON PUGET SOUND REGIONAL COUNCIL
The Expert Arbitration Panel on Noise and Demand/System
Management Issues (the "Panel ") has carefully considered the
arguments and evidence with respect to what we have termed Phase I of
the Noise Issues. Written and oral submissions on these issues
have been presented to us by the Port of Seattle ("POS"), the Puget
Sound Regional Council ("PSRC"), the Washington State Department of
Transportation ("WSDOT"), the Federal Aviation Administration ("FAA"),
the Coordinating Committee and by a variety of groups and individuals
representing residents of communities affected by Airport noise,
including the Regional Commission on Airport Affairs ("RCAA"), the
Airport Communities Coalition ("ACC"), the Airport Noise Group ("ANG")
and many individuals who appeared before the Panel to offer their
comments to us. On December 2, 1994, we announced our decision
on the scope of the Panel's inquiry on Noise Issues and indicated that a
written order was soon to follow. Thereafter, we received some
additional written submissions by the POS, the RCAA, the Federal Way
Chapter of the RCAA, the ACC, the ANG and Air Washington.
This is the written order containing our decision on the scope of the
Panel's inquiry on Noise Issues.
We have concluded that our role under PSRC Resolution A-93-03 is
to determine whether the POS has scheduled, pursued and achieved a
reduction in measurable, real on-the-ground noise impacts. To meet its
burden under the Resolution, as we interpret it, the POS must offer us
reliable evidence, based upon actual measurements of on-the-ground
noise, that by 1996 there has been an objectively measurable,
meaningful reduction in aircraft noise impacts in the affected
communities surrounding the Airport.
Under the Resolution, it is not enough for the POS to show that it has
met the goals of the Noise Budget and the Nighttime
Limitations Program (or the goals of additional programs specified by the
Mediated Noise Agreement). Rather, the POS must establish that
through whatever means, it has reduced the impact of on-the-ground
noise in a way that residents of the affected communities could
appreciate. In our view, therefore, proof of compliance with the
Mediated Noise Agreement is useful, but not necessarily sufficient, to
establish that the noise reduction requirement of the Resolution
has been met.
[Page 2]
We are convinced that the Resolution was intended to condition the
approval of the third runway upon a showing that the noise impacts of
the existing Airport have been educed in a significant way. This means,
to us, that it is not enough only to show that there has been a
measurable reduction in average sound levels as determined by the
Day-Night Level (DNL) metric using the existing Airport Noise Monitoring
System. A measurable reduction of that sort might be so small, or have
such a character, that even by objective standards, it could not be
expected to make a material difference to the communities that surround
the Airport. The 11 remote monitoring sites (RMS) of the existing Noise
Monitoring System may also not be sufficiently representative of the
locations of significant on-the-ground noise impacts generated by
aircraft using the Airport.
The question we must decide is whether there has been a reduction
in real noise impacts that by objective measures is significant and
meaningful. We are not persuaded that the deletion of the words
"reasonable, meaningful" from the description in the PSRC's
Implementation Steps of the reduction in on-the-ground noise to be
validated is of any consequence. We do not believe
that either an "unreasonable" (i.e., unreachable or infeasible) or a
"meaningless" (i.e., inappreciable or trivial) reduction in noise was
contemplated by the Resolution, The POS has not demonstrated that the
Noise Validation Methodology (NVM) presented in Noise Validation
Methodology in Compliance with PSRC Resolution A-93-03 ("the NVM
Report"), as it exists today, would be a valid method of determining
whether the required reduction in on-the-ground noise has occurred
even if it were a valid method of measuring success in meeting the
ANEL goals of the Noise Budget. The Panel does, however, note
several important points about the proposed NVM:
* The proposed NVM is based, as it should be, on measured, not
predicted, on-the-ground sound levels.
* The proposed NVM, as it should, measures on-the-ground noise from
all Airport noise sources, not just landing and departing domestic
commercial aircraft that are subject to the noise budget. [Footnote 1]
* The proposed NVM, however, depends entirely upon sound levels
that have been and will be measured only at the I I existing RMS
around the Airport.
* The POS has not demonstrated that the I I RMS will adequately
reflect the levels experienced by a representative sample of the
impacted population. [Footnote 2]
[Page 3]
* The POS has not demonstrated that data from the I I monitoring sites
are sufficient to confirm whether the ANEL noise reductions
in the Noise Budget will be achieved. [Footnote 3]
* The POS has not demonstrated that the arithmetic average of a set
of monitored data (as used in the NVM) will give the same
target reduction as an energy summation of the same data (energy
summation is used in the Noise Budget). [Footnote 4]
As a result, a revised NVM will be required.
We recognize, however, that the Resolution contemplates that
objective measurements of on-the-ground noise will be
used. -this means that the POS will not be required to conduct surveys
of residents in the affected communities to ascertain their subjective
perceptions of Airport noise. This is not to say that such survey results
would not provide useful information to the POS and the public, and to
this Panel. We also acknowledge that the Resolution does not require
the POS to reduce Airport noise to "acceptable" levels, whatever they
may be. Rather, the Resolution only requires that the POS achieve a
significant reduction in the real noise impacts. Busy jet airports, such as
Sea-Tac, are inherently noisy, and it is unrealistic to expect that nearby
communities would ever find the noise impacts generated by such
airports to be "acceptable."
The question therefore becomes (a) what measures of noise impacts
should be used (that is, what noise "metrics" should be selected), (b)
where should the measurements of noise be made, and (c) how much
reduction in noise, by these measures, must be achieved, and over what
time period, to satisfy the requirements of the Resolution?
We turn first to the choice of metrics. We recognize, as the POS has
urged, that DNL is a valuable tool, and we intend to give significant
weight to reductions in DNL that are shown by the POS. However, we
have concluded that the use of the DNL metric, by itself, is inadequate
to show the required reduction in noise impacts because, taken alone,
as an aggregate value it does not permit us to review the intensity,
duration or frequency of single noise events or to consider when, during
the day or night, they occur (even though all of these attributes
contribute to the measured DNL). [Footnote 5] As a result, we
[Page 4]
encourage the POS to develop a method that supplements the use of
DNL observations with various additional metrics (including sound
exposure level (SEL), Time Above (TA) an appropriate sound level
threshold, and unweighted sound pressure levels). The revised method
should also explicitly report changes in the total number, as well as in
the composition and day/night mix, of aircraft operations at the
Airport. Unless the reduction in sound levels is more fully characterized
than the use of only DNL allows, we will be unable to find -that there has
been a meaningful reduction in real on-the-ground noise impacts, as
required by the Resolution. [Footnote 6]
We turn next to the location of noise monitors. We have concluded
that the use of measurements of on-the-ground noise from the existing
Noise Monitoring System at Sea-Tac is, without more evidence,
nsufficient to show the required reduction in noise impacts because
these measurements do not capture
[Page 5]
significant aircraft-generated on-the-ground noise beyond the immediate
periphery of the Airport. We encourage the POS to expand the Noise
Monitoring System so that it is capable of collecting on-the-ground noise
measurements at a variety of additional locations throughout the
affected communities. At a minimum, we would like to see the POS to
collect on-the-ground noise measurements at six additional remote
monitoring sites. "These should include sites beyond the boundaries of
the predicted 65 dB DNL contours (with the most recent available
Noise Exposure Map input data being a reasonable guide), both
farther out along major flight corridors and farther out to the east and
west of the Airport. [Footnote 7] As part of a revised NVM process, the
POS should propose a detailed measurement plan that demonstrates a
measurement sampling strategy which produces statistically acceptable
representations of the annualized DNL and any other descriptors
developed for the revised NVM. We feel that it is important for the POS
to show us that noise impacts have been reduced where the affected
population lives and where noise sensitive land uses, especially
schools, are located. [Footnote 8]
We turn last to the required reduction in noise impacts. This is the
most difficult question. We have determined that under the Resolution,
the POS has the burden of showing that whatever reduction it has
achieved by 1996 is significant and meaningful in the sense that
residents of the affected communities could, or should, appreciate it.
It is not for us to say exactly what metrics the POS should use, or
precisely how large a reduction in sound levels it must prove. Rather,
the POS must show us (i) that it has articulated an appropriate standard
for judging whether the reduction in noise impacts is sufficient, and (ii)
that by that standard, the POS has achieved the required reduction. We
do note, however, that we are not convinced that the FAA threshold for
considering increases in sound levels to be significant for certain
regulatory purposes (+ 1.5 dB increase in annual average DNL) is a
satisfactory benchmark for our use in judging whether the reduction in
real on-the-ground noise impacts achieved by the POS satisfies the
requirements of the Resolution. [Footnote 9]
[Page 6]
We have also determined that 1993 is the appropriate base year for
purposes of the measuring whether the reduction in noise impacts
required by the Resolution has been achieved. Nothing in the
Resolution speaks to noise reductions that occurred before the
Resolution was enacted. [Footnote 10] Thus, as we read it, the
Resolution requires the POS to show that there has been a significant
reduction in on-the-ground noise impacts from 1993 to 1996, when the
construction of the third runway may be authorized by the PSRC.
We are not insensitive, however, to the practical problems our
interpretation of the Resolution may create for the POS. Most
prominently, the requirements that the POS employ additional
noise metrics and monitoring stations, and that it show a reduction in
noise from 1993, will inevitably require the POS to back-
calculate or otherwise estimate some of the required inputs. While this
may introduce some imprecision into the exercise, we have concluded
that it is preferable to using only DNL data from the existing Noise
monitoring System for past years or limiting the analysis entirely to
future noise reductions. The Panel believes, however, that the
significance of the 1993-96 data will be best understood in the context of
as much earlier data as the POS can make available to us.
[Page 7]
As we have said, we do not believe that it is our responsibility to
specify exactly how the POS should meet its burden of showing that the
required reduction in on-the-ground noise impacts has occurred.
Rather, it is our role to indicate, in general terms, why the Noise
Validation Method, as it has been proposed by the POS, is not
adequate, and what sorts of additional Considerations should be taken
into account. We have attempted to do so in this Order. We leave it to
the POS, and its consultants, to develop and articulate a new method of
making the required showing to us.
We do not believe that we have any authority to compel the POS to
adopt any particular approach to the reduction of on- the-ground noise
impacts. We do feel, however, that it might be useful for the POS (in
conjunction with the FAA, where appropriate) to consider a variety of
measures for both noise abatement (reduction of total sound energy at
the source) and noise mitigation (reduction of noise impacts). With
regard to the programs that were deemed to be "responsive" in Part III.A
of the Implementation Steps adopted by the Executive Board of the
PSRC, we offer these comments:
* Acoustical insulation program: Based on testimony at the hearings
(and subject to our reevaluation after review of the data requested in the
Attachment to this order), we are concerned that the acoustical
insulation program does not appear to be meeting at least one of its
stated goals, which is a 5 dB reduction in A-weighted DNL in the treated
houses. The POS also appears not to be meeting its design goals for
each individual house for additional Noise Level Reduction after
nsulation. Additionally, a 5 dB reduction in overall A-weighted DNL may
be too modest a goal for meaningful reduction in interior noise due to
aircraft, especially in the lower frequencies. [Footnote 11] Meaningful
noise reduction due to sound insulation may need to address this low
frequency noise. Independent, periodic and statistically supportable
measurements of a representative sample of the insulated homes before
and after treatment would be useful.
* Run-up noise reduction program: Based on our review of the data
provided by the POS, we are concerned that the nighttime engine run-
ups may regularly violate the King County Noise Ordinance, and
perhaps by substantial amounts. Full POS compliance with the King
County
[Page 8]
Noise Ordinance for all run-up activities covered by the Ordinance would
seem to be appropriate. In addition, whatever abatement measures the
POS uses to reduce regulated run- up noise (such as a hush facility)
might usefully be applied to the exempt daytime and nighttime
operations as well. We would suggest that the POS demonstrate
compliance with the Ordinance through measured data at appropriate
measurement points in the residential areas surrounding the boundaries
of the Airport. We would further suggest that independent
measurements be made by trained County staff or by an independent
consultant hired by the PSRC. We would encourage the POS to include
in the revised NVM a plan to use measures other than mere compliance
with the Ordinance and the run-up noise reduction program, such as
sound level measurements and operational data, to demonstrate that
meaningful reductions in ground run-up noise have occurred.
With regard to other programs or measures that were not listed in Part
III.A of the Implementation Steps, we would suggest that the following be
considered:
* Evaluate and, if feasible, implement alternative flight paths designed
to minimize the population exposed to maximum noise levels or to
redistribute the burden of maximum noise levels throughout the
surrounding communities. [Footnote 12]
* Consider and, if feasible, implement revised flight operating
procedures to increase the angle of ascent/descent for jet aircraft at the
Airport, to reduce on-the- ground noise levels along the flight paths and
at the corner posts.
* Implement a high-priority program to install, by the end of CY 1996,
sound insulation in all elementary and secondary schools within the 65
dB DNL contour sufficient to reduce sound levels in classrooms due to
aircraft to a maximum level and duration that will eliminate speech
interference. [Footnote 13]
[Page 9]
* Further accelerate the residential sound insulation program.
[Footnote 14]
* Evaluate the feasibility of new technologies to reduce ground noise
generated by jet engine runups and, if feasible, adopt new methods of
doing so.
* Evaluate the feasibility of-setting a cap on total nighttime operations
and, if feasible, implement such a cap.
* Evaluate the feasibility of shifting nighttime operations to earlier in
the evening or later in the morning and banning all operations for a core
period in the middle of the night; and, if feasible, implement these
measures.
* Evaluate the feasibility of setting a maximum noise limit (SEL or
Lmax) for aircraft operating during the nighttime hours, and, if feasible,
implement such a limit. [Footnote 15]
We recognize that in its efforts to limit and reduce the impact of
aircraft-generated noise on its neighbors, the POS has been a leader
within the airport industry. The POS has expressed confidence that
through its innovative Noise Budget and Nighttime Limitations Program,
and various other efforts, it is in fact significantly reducing the impact of
on-the-ground noise. We invite the POS to show us why the community
should share the POS's confidence in the significance of its on-going
noise abatement and mitigation programs. [Footnote 16]
The POS should submit a revised noise validation method to the
PSRC, for delivery to us and for public inspection, by March 31, 1995.
Any member of the Coordinating Committee or of the public who wishes
to offer comments on the revised method submitted by the POS should
submit written comments to the PSRC, for delivery to us, by April 14,
1995. We expect to convene a public hearing, to consider the POS's
submission and responses from the Coordinating Committee and the
public, during the first week of in May 1995. We will, in due course,
issue an order specifying the time and place of such a hearing.
In anticipation of our review of a revised noise validation method, the
Panel believes that it would be helpful if the POS could provide us with
the technical information specified in the attached Information
[Page 10]
Request to the Port of Seattle by submitting the requested information to
the PSRC, for delivery to us, by February 28, 1995.
We want to reiterate here a final comment that we offered on those
issues at the conclusion of the hearing on December 2. Throughout this
proceeding, the public has attempted to draw to our attention the
consequences -- particularly the noise impacts -- that might occur if a
third runway were built at the Airport. We again observe that this Panel
cannot and will not undertake a review of the potential environmental
consequences of building the third runway. Our responsibility, with
respect to the Noise Issues, is limited to determining whether the
POS has scheduled, pursued and achieved a meaningful reduction in
real noise impacts at the existing airport.
We will soon issue a separate order laying out the next steps for our
consideration of Demand/Systems Management Issues.
Scott P. Lewis, Chair
William Bowlby
Martha Langelan
Date: January 9, 1995
[Footnote 1] These sources include nighttime
as well as daytime, flights, cargo flights,
international flights, military flights and
general aviation flights, plus all noises
made by aircraft or auxiliary
equipment while on the ground (including
taxiing and ground run-up during maintenance
and repair). Thus, the proposed NVM
measurements include actual noise that was
excluded from the Noise Budget calculations.
The proposed NVM measurements would also
likely include noise from aircraft operating
at nearby airports.
[Footnote 2] There are sites in areas where
no people live, and no sites are in areas
where the 1989-90 annual average DNL used in
the NVM baseline calculation was below 71 dB.
Sites would seem to be needed that are
representative of the impacted population,
not just the severely impacted population;
sites are needed where the DNL are in the 55-
70 dB ranges, as well as where the DNL
exceeds 70 dB. Because the current Noise
Monitoring System is limited to sites very
close to the Airport, the average NVM DNL of
74 dB, observed at the 11 RMS, does not
reflect the lower levels of noise that are
experienced bv most of the impacted
population.
[Footnote 3] The ANEL includes calculation
points at +60,000 and +90,000 fee from the
start of take-off roll (m well as +30,000
from take-off roll and -20,000 feet from
landing touchdown).
However, the most distant RMS is only 29,000
feet from the start of take-off roll, and
most of the 11 RMS are closer than the
shortest distance in the ANEL (20,000 feet).
Thus, assertions about differences among
aircraft in arrival or departure noise at
greater distances out from the Airport remain
untested.
[Footnote 4] The proposed NVM DNL goal is
the arithmetic average of the actual energy-
average DNL at the 11 RMS. The ANEL in the
Noise Budget is the level of the sum (not the
average) of the sound energies at four other
points. If the NVM were to use the sum of
the sound energies at the 11 RMS instead of
the arithmetic average, the results will
change slightly from what is currently shown
in the NVM Report. While the difference
would normally be of little consequence, the
POS is presenting its ANEL
goals with year-to-year reductions in the
range of 0.2 to 0.4 dB. Also, as previously
noted, the POS has not demonstrated that the
reductions at the relatively close-in 11 RMS
represent the reductions at more distant, yet
impacted, sites.
[Footnote 5] For example, a 3 dB reduction
in DNL would occur if either (i) there were a
50% reduction in the noise energy generated
by each aircraft using the Airport (but no
change in the
frequency of operations) or (ii) there were
no change in the noise energy generated by
each aircraft, but a 50% reduction in
operations in operations at the Airport.
While these two changes would be equivalent
in DNL terms, the impacts on
the surrounding communities would be very
different.
[Footnote 6] Additionally, we have concerns
over the manner in which DNL is currently
measured. The currently installed I I RMS
report a DNL attributable to aircraft alone
as well as a DNL capturing all the noise at a
site. The proposed NVM has left open the
option to use either of these levels. The
Panel believes that the NVM should include
both the total DNL and aircraft DNL, because
of the following concerns.
First, the "total DNL", by definition,
captures all noise at a site. Improper
placement of an RMS hydrophone (or loss of
its windscreen) could cause the RMS to
measure high levels of non-aircraft noise
that are not truly representative of what the
people are experiencing on the ground. It is
possible that the total DNL in the base
period could be slightly, artificially and
incorrectly high.
Elimination of this problem in a subsequent
evaluation year could result in a different
(and lower) measured level that is not due to
a reduction in aircraft noise. If nothing
else, the background level will appear to be
artificially high, making the increase over
background artificially low and making the
impact of aircraft noise seem less than it is
in reality. Our visits to several of the RMS
gave us the clear impression that some of the
"community DNL" measured by the Noise
Monitoring System and shown in
the NVM Report were too high. We have
already expressed concern in the hearings
that the hydrophone noise floors are too high
for accurate measurement of the background
levels, which is of particular importance
when computing the nighttime contribution to
DNL. We raise these issues because we note
that the difference between background and
aircraft levels has been cited in several
studies made by the public in the hearings as
one influence on annoyance.
Another concern is that placement of a
monitor could result in the capture of a high
level of actual non-aircraft noise. If this
noise is indeed representative of the ambient
noise experienced by
nearby residents, it should be measured.
However, the goal of the Resolution is to
show a reduction in aircraft noise. A very
high level of actual background noise would
make it difficult, if not impossible, for the
POS to demonstrate future reductions in
aircraft noise using the "total DNL" measure.
On the other hand, if the non-aircraft noise
measured by an RMS is not representative of
what the nearby residents hear, the "total
DNL" that is reported could be higher than
what the people actually experience. This
could occur, for example, if the RMS is on a
pole at a height that exposes it to traffic
noise from which residents at ground level
are shielded due to terrain features. As a
result, the POS might not be able to show the
full extent of the reduction that has
occurred where the people live.
A final concern is that we have not been
convinced that the algorithm used by the
Noise Monitoring System to assign noise to
the "aircraft" noise category rather than the
non-aircraft or "community" noise category
are sufficiently reliable. Of particular
concern is noise generated while the aircraft
are on the ground, such as from taxiing,
reverse thrust on landings and engine run-ups
of all
kinds. This problem would suggest that it is
more appropriate to base an evaluation on the
total noise measured at the RMS.
[Footnote 7] We note that the POS' FAR Part
150 Noise Compatibility Program Amendments of
1993 already call for evaluating the adequacy
of the monitoring system. This work was to
be initiated in 1994, yet we heard nothing
about its progress at the hearings. We note,
however, that both the POS and various
representatives of the public mentioned in
the hearings and in the written submittals a
variety of potential new sites that warrant
consideration.
[Footnote 8] We also feel that it would be
useful if the revised NVM included a plan for
periodic, independent spot-check sound level
monitoring and for more frequent visual
verification of RMS
condition. It would be useful if the spot
checking included comparisons with the RMS
data on an event-by-event-basis to determine
any discrepancies in the RMS measurements of
aircraft-only noise, background noise, and
maximum level or SEL of events. It would
also be useful if the spot-check equipment
was capable of accurately measuring the
minimum background noise levels at each site.
Additionally, it would be desirable for the
POS to file with the PSRC monthly monitoring
results reports, complete with statistics on
the data and annotation of all potentially
spurious data. Finally, an independent
review of the records of the past field
visits to the RMS that could identify the
extent and effect of any recorded problems,
as well as an evaluation of the current sites
and the RMS' condition, would also be useful.
[Footnote 9] The purpose of the FAA's
threshold (in areas where the DNL is already
above 65 dB) is to determine when further
analysis is necessary; not to deem that a
significant impact has automatically
occurred. A 1.5 dB DNL increase could result
from an imperceptible 1.5 dB increase in the
SEL of each aircraft or a very perceptible
40% increase in the number of operations.
Likewise, an introduction of operations to an
area previously without them could raise the
DNL by 1.5 or more dB and generate
substantial community reaction. A good local
example of the latter was the reaction to the
Four-Post Plan in areas beyond the 65 dB
contour, where 3 dB increases in DNL were
predicted by the POS noise consultant. The
FAA threshold for further analysis is a
signal to investigate the cause of the DNL
increase, and to ascertain whether that cause
has significant impact.
We also note that the 1992 FICON Federal
Agency Review of Selected Airport Noise
Analysis Issues submitted to us by the POS
compiles a variety of other thresholds
articulated by various people for various
purposes. FICON suggests that "percent of
people highly annoyed" (%HA) is a good
indicator of environmental quality, with
reference to Finegold's work and the revised
Schultz curve. In the hearings, the POS
noise consultant also referred to %HA citing
values from the curves in the 1992 FICON
review. He noted that the POS' proposed 4.4
dB reduction in average DNL by 2001 would
reduce %HA by 40 or 50 9.. We note somewhat
different values: a 50 % reduction in %HA
(such as from 20% to 10%) would actually
require a 6 dB reduction in DNL according to
the curves. The POS consultant also referred
the Panel to the 1991 Fidell article (JASA,
89/1, pp. 221-233), which presents the
"revised Schultz curve; * this curve shows
that a 4.4 dB decrease in DNL would reduce
the %HA by about 25 %; to achieve a 50 %
reduction in %HA, according to the revised
Schultz curve, a 9 dB decrease in DNL would
be required.
We also note that A. Harris in a
December 23, 1994, letter to the Panel and in
his 1990 Review of Community Responses to
Changes in Noise Exposure, submitted to us by
the ACC, suggests
that determination of differences in the
number of impacted people represented by each
study point is key to assessing the
effectiveness of a change in the noise
climate, coupled with changes in noise
exposure and single event levels.
Further, the POS consultant noted that
Fidell had reaffirmed the idea that the use
of a single curve representing all
transportation sources was valid. A. Suter,
in her review prepared for RCAA for the
hearings, disagreed, citing many recent
references not addressed by Fidell or by
FICON. She pointed to data that would raise
the %HA for 70 dB DNL from the 20-30% range
to over 70%.
Also, a second Fidell article provided to us
by the POS consultant (JASA, 89/1, pp. 234-
243) showed a 5 dB "shift" in tolerance of
aircraft exposure compared to non-aircraft
exposure (people being less tolerant of
aircraft noise, and so, more likely to be
highly annoyed by a given aircraft DNL than
by non-aircraft sources such as road
traffic).
We believe all of these references offer
insight into the significance of changes in
noise exposure and DNL.
[Footnote 10] It seems implausible to us the
Resolution would be satisfied if a meaningful
reduction in noise impacts occurred between
1989 and 1993, but noise impacts are
aggravated from 1993 to 1996.
[Footnote 11] Wyle Research notes on page 2-
5 of its Guidelines for the Sound insulation
of Houses Exposed to Aircraft Noise, provided
to the Panel by the POS, "Modest improvements
. . . (e.g., less than 5 dB) may not provide
a noticeable improvement to the homeowner and
hence are not cost effective." Further, on
page 2-6, Wyle Research notes, ". . . the
FAA has recognized that in order for a
homeowner to perceive any improvement . . .
there must be a minimum of 5 dB improvement
in noise reduction in each room" [our
emphasis]. Wyle Research also notes that
interior SEL goals of 60-65 dB may also be
appropriate in areas within the 65 dB
exterior DNL zone.
Additionally, as the POS noise
consultant indicated in the hearings, the
reduction in A-weighted DNL is caused solely
by a reduction in maximum A-weighted levels
(and SEL) of individual aircraft. We suspect
that this reduction is probably driven by a
reduction in the more easily attenuated
frequencies near and above 1000 Hz, with
perhaps little or no reduction in the more
difficult-to-reduce lower frequencies (which
are heavily attenuated in the A-weighted
calculation). It is these lower frequencies
that seem to be the cause of much of the
complaints about interior noise impacts
(including window rattle). A 5 dB reduction
in overall A-weighted level from an
individual flyover may not be sufficient to
be viewed by residents as a meaningful
improvement. Even an 8-10 dB reduction in
overall A-weighted level, which would
typically considered as substantial, may not
adequately solve the low frequency noise,
vibration and rattle problems.
Finally, POS data provided to the Panel
by the Pork Patrol (Final Project Report,
Summary of Test Results, AIP 3-53-0062-13)
shows many cases where the actual measured
"additional sound reduction after insulation"
was less than the "designed additional sound
reduction".
[Footnote 12] We note that in Resolution A-
93-03, the PSRC specifically requested
*consideration by the FAA of modifying the
Four-Post Plan to reduce noise impacts . . .
" We also make note of the discussions in the
December hearings that the FAA has invited
the local communities to be involved in the
process of evaluating flight path shifts.
While such involvement has the potential to
pit one community against another, we feel
that careful examination of shifting the
'posts" and perhaps narrowing the approach
and
departure corridors outside the posts could
produce a worthwhile net benefit in noise
exposure. It is clearly in the best interest
of the POS, the PSRC and the citizens to
pursue vigorously this option.
[Footnote 13] We note, according to the 1992
FICON airport noise analysis review, that 60
dB is given as the level above which "there
will be interference with speech
communication. "We also note that in the FAR
Part 150 Amendments of 1993, the POS called
for a planned pilot program on sound
insulation of two churches, one private
school, one convalescence home and one multi-
family structure. We suggest that there is
enough evidence nationwide of successful
noise insulation activities that a pilot
program is unnecessary and that full
implementation of a public use/multi-family
structure noise insulation program could
begin immediately. We also believe that
special emphasis should be put on schools and
convalescence facilities in this program.
At a minimum, we believe that it would
be very useful for the POS to complete the
pilot program by mid 1995, as the POS
anticipated in the Part 150 Amendments, and
that a regular public
use/multifamily structure insulation program
could be well underway by April 1996, with a
detailed schedule for completion, including
documentation of which facilities are
eligible, which are not (and why not) and the
insulation goals.
[Footnote 14] We note that the POS FAR Par(
150 Amendments of 1993 indicate that 7,500
single family residences are eligible for
sound insulation and that the POS has
accelerated the program to 100 houses per
month. Even with this acceleration,
completion of the program will take until
2001.
[Footnote 15] We note that Section 4.C of
the Nighttime Limitations Program calls for
the POS to specifically determine, after
1997, "with input from the carriers and the
public whether [such a limit] . . . is
appropriate and consistent with its
obligation as an airport proprietor." We see
no reason why this decision should be put off
so long.
[Footnote 16] We note that the data in Table
17b of the POS response to our September 1994
data request shows a 2.9 dB drop in measured
DNL at the 11 RMS from 1991 to 1994 YTD (and
a
corresponding 2.7 dB drop in the related
ANEL); which already exceeds the 1998 DNL
goal in the NVM Report (and the 1999 goal in
the Noise Budget). The NVM Report showed
that from 1991 to
1994, the DNL had to drop 1.0 dB,
corresponding to a 0.76 dB decrease in ANEL.
Attachment 1 to January 9, 1995 Order on
Phase I Noise Issues
INFORMATION REQUESTS TO THE PORT OF SEATTLE
The Panel respectfully requests that the Port
of Seattle (POS) and its consultants provide
the following information. We ask that each
item's information be provided when ready
rather than waiting until all items are
ready.
1. Please provide the following data on the
sound insulation program:
a. full details on the noise
measurement test program for sound insulated
homes, including how many have been tested,
how many are tested each quarter, how the
houses to be tested are chosen, and who
conducts the measurements and the data
analysis;
b. measured sound level data for all
insulated houses that have been tested;
please provide this data separately in terms
of sound exposure level (SEL) and maximum
level outdoor-to-indoor Noise Level Reduction
before and after treatment for these houses;
for a representative sample, please show
octave band (or 1/3 octave, if available)
sound pressure levels (SPL) and A-weighted
levels, plus overall SPL and A-weighted level
for the same data;
c. an explanation of the measurement
procedure and sampling strategy for each
test, including the number of samples, types
of aircraft and operations represented by the
data, aircraft positions relative to the
house during the test, and a map locating the
houses represented in the submitted data;
d. a sample actual calculation from
the field-measured data of the resultant Day-
Night Level (DNL) reduction;
e. the mean overall A-weighted sound
level change for all insulated houses, the
mean Noise Level Reduction for the houses,
and the mean cost per house (with plus/minus
one standard deviation for all means); please
indicate the number of samples used in the
calculation of the mean(s);
f. the total number of insulated
houses, the number yet to be treated, and the
schedule for treating the remaining houses
g. the total number of elementary and
secondary schools and convalescence
facilities within the existing noise
mitigation zone.
2. Please provide tables of statistics on
measured DNL at the I I remote monitoring
sites, showing for each site for each year
since (and including) 1989:
a. mean measured TOTAL DNL at a site
for the year (and the number of days in the
calculation), plus/minus one standard
deviation, 95% confidence limits, and
frequency distribution histogram (in one
decibel increments) for the year;
b. mean measured AIRCRAFT-ONLY DNL at
a site for the year (and the number of days
in the calculation), plus/minus one standard
deviation, 95% confidence limits, and
frequency distribution histogram (in one
decibel increments) for the year.
3. Please provide a table summarizing the
statistical significance (at the 5% level of
significance) of the differences in the means
in item 4 above (by site, separately for
TOTAL and AIRCRAFT-
ONLY) for 1989 compared to each year; please
indicate the statistical test used to test
significance and show the relevant calculated
evidence of significance.
4. Please provide a table summarizing the
statistical significance (at the 5% level of
significance) of the differences in the means
in item 4 above (by site, separately for
TOTAL and AIRCRAFT ONLY)for each year
(starting in 1989) compared to each
subsequent year; please indicate the
statistical test used to test significance
and show the relevant calculated evidence of
significance.
5. Please provide a table summarizing the
statistical significance (5% level of
significance) of the difference in the mean
DNL (averaged over the I I sites)for 1989
compared to each year; please indicate the
statistical test used to test significance
and show the relevant calculated evidence of
significance.
6. Please provide a table summarizing the
statistical significance (5% level of
significance) of the differences in the mean
DNL (averaged over the II sites) for each
year (starting in 1989) compared to each
subsequent year; please indicate the
statistical test used to test significance
and show the relevant calculated evidence of
significance.
7. Please provide corrections to Table C-78
et al. of the Flight Plan Project FEIS for
the population in the 80 dB SEL contour for
Alternatives 1, 33, 34 and 35. Please
provide an explanation of any differences in
the SEL population trends between Alternative
I and the other alternatives compared to The
DNL population trends in the same tables.
8. The December 14, 1994 letter from Mr.
Dunholter to Ms. Summerhays referred, on the
3rd page, 3rd full paragraph, last sentence,
to other current research that replicates the
British findings on sleep interference.
Please provide citations and
abstracts/conclusions from these works. The
12/7/94 letter to
the panel from Mr. Peter Townsend of the
Federal Way Chapter of the RCAA offered to
provide a critique of this British study. We
request that Mr. Townsend be asked to provide
the critique.
9. At the December hearing, Mr. Duriholter
showed a chart comparing DNL and complaints
received by the POS. Please send us a copy
of that chart and any relevant back-up
information.
10. At the December hearing, Mr. Wells of the
POS noted that 1-second data from the Noise
Monitoring System has been stored for about a
year. He also noted that, in the past, SEL
data was not generally recoverable unless the
system "was set to generate SEL numbers"
which "is not routinely done."
a. Please specify the times periods,
if any, in the past during which the system
was set to generate SEL data, perhaps for
special studies that were being conducted; to
the extent that such past SEE data is
available (regardless of whether or not it
can be correlated to specific events), please
provide tables summarizing this information
in 5 dB increments (number of events in each
5 dB range) for each period measured.
b. Please indicate the exact period(s)
for which the more recently collected 1-
second data is available.
c. Please use a sample of the 1-second
data to present the SEL for one departure
event that was measured at all (or a major
portion) of the RMS locations and the
correlated nonnoise data on the event,
describing briefly the process used to
identify the event and to then obtain both
the noise and nonnoise data.
d. Please use another sample of the 1-
second data to present the same information
for a maintenance or repair ground run-up for
a Boeing 727.
e. Please indicate how the
capabilities have changed since the recent
addition of the new software, and illustrate
the same type of event identification and
analysis.
f. Please provide a sample histogram
of SEL (in 2 dB increments) at RMS #5 for a
typical day using the new software's
capabilities and showing if and how ground
run-up events are included; please show the
corresponding operations data for that same
day, correlating events to SELS.
11. We ask the POS to request a letter from
King County giving the County's
interpretation of the, County Noise Ordinance
as it
relates to the Airport ground noise. In
particular, we are interested in the daytime
exemption from 7 a.m. to 10 p.m. and the
special exemption from 6 a.m. to 7 a.m. (as
mentioned in the March 1994 POS South
Aviation Support Area FEIS on pages 4-37, 4-
66 and 4-73).
We would like a response to the following
observations:
The fleet mix used in the ANEL-to-DNL
conversion in Noise Validation Methodology
iii Compliance with PSRC Resolution A-93-03
("the NVM Report") was said to represent a
mix designed to give the maximum possible DNL
reduction for a given ANEL reduction. The
report showed that from 1991 to 1994, the DNL
should drop 1.0 dB, corresponding to a 0.76
dB drop in ANEL.
Yet, Table 17c of the POS Response to
our September 1994 data request shows that,
based on the actual 1994 YTD (year-to-date)
operations, a 3.6 dB reduction relative to
1991 should have occurred using the NVM
formula. While ANEL is not shown in Table
17c, we would expect the related ANEL
difference from 1991 to 1994 YTD to be over 3
dB. Both the NVM DNL and the ANEL reductions
computed from the 1994 YTD operations data
are radically different from the forecast 1.0
and 0.78 dB reductions in the NVM Report.
At the December hearing, Mr. Bryant of
the POS attributed the larger decrease to the
nighttime Stage II limitations program phase-
in at the end of 1992. The Panel wonders why
this effect was not accounted for in the
calculations in the NVM Report if, as stated,
the Report used fleet mixes designed to give
the maximum DNL reduction. Is it simply the
fact that the airlines' Stage III conversion
was much more rapid than they were willing to
agree to in the Noise Mediated Agreement?
Also, the actual measured data in Table
17b of the POS Response to our data request
shows a 2.9 dB drop in measured DNL at the 11
RMS from 1991 to 1994 YTD (and a
corresponding 2.7 dB drop in the related
ANEL). Are we correct in interpreting this
result as meaning that the POS is already
exceeding the 1998 goal for DNL in the NVM
Report, as well as the 1996 goal upon which
the POS has proposed that we base our
decision. (It appears that the reduction also
exceeds the 1999 goat for ANEL in the Noise
Budget.) Should the Panel interpret these
results to mean that the goals in the NVM
were much too modest? Should we expect a
reduction through 1996 that follows the trend
from 1991 to 1994?
Please describe the procedures the POS
would use to determine (i) where additional
noise monitoring sites should be located, and
(ii) how many additional sites would be
appropriate, if the existing Noise Monitoring
System were to be expanded to
provide a better population emphasized basis
for evaluating on-the-ground noise impacts.
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