Minutes Exhibit C
Minutes Exhibit C
Port Commission Special Meeting
March 12, 2019
STATE OF WASHINGTON
PUGET SOUND REGIONAL COUNCIL
Inthe Matter of
Expert Arbitration Panel's Review ofNoise and
Demand/SystemManagement Issues at Sea-Tac
International Airport
FINAL DECISION ON NOISE ISSUES
March 27, 1996
This is the Final Decision on Noise Issues by the Expert Arbitration Panel on Noise and Demand/System
ail ofthe
Management issues (the "Panel"). After making a thorough and independent evaluation of
evidence andarguments that have been presented to us with respect to the reduction in noise impacts
required by Resolution A-93-03 as a condition for the Puget Sound Regional Council's approval ofa third
ofProfessor William Bowiby
runway at Sea-Tac International Airport, a majority ofthe Panel, consisting
and Ms. Martha Langelan, has reached the following conclusion:
Although the Port of Seattle has scheduled pursued, and achieved an impressive array ofnoise abatement
and mitigation programs, the Pori has not shown a reduction in real on-the- ground noise impacts
sufficient fo satisfy the noise reduction condition imposed by Resolution A-93-03.
Mr.Scott P. Lewis, Chair of the Panel, would find that the Port has satisfied the requirements ofthe
Resolution,anddissentsfromthisDecision
We offer below a-statement ofthe background and history ofthe Panel's consideration ofNoise Issues
under Puget Sound Regional Council ("PSRC") Resolution A-93-03, a summary ofthe basis ofthe
majority's decision,recommendations about firture efforts that couid be taken to reduce the burden of
aircraft-generatednoiseonthecommunitiessurroundingthe Airport, astatement ofthe dissent, and
someclosingcomments.Inthemajority's findings and conclusions, we have assumed the Port's
compliancewith the Noise Mediation Agreement (including the reliability ofthe Noise Validation
Method),svaluatedthe effectivenessofthe Port's noise abatement and mitigation efforts with respect to
on-the-ground noise impacts,andaddressed the natureofthe ‘meaningfil” and “reasonable” reductions inreal
noiseimpacts’ requiredbyResolution A-93- 03.
iS
[PAGE 1
(BY THE PANEL)
TrasporationpsE inted in
June 1994 byritofthe Panel followed the adoption ofResolution A-93=the Secretary ofthe Washington State Departmentof
by the Puget Sound Regional Sound, the PSRC's promulgation ofimplementation Steps" for the Panel,
and the execution ofa Memorandum ofUnderstanding ("MOU") among the PSRC, the Federal Aviation
Administration ("FAA"), the Port of Seattle ("Port” or "POS") and the WSDOT.
The Resolution, which appears to us to be unique, provides that the region should pursuevigorously a
major supplemental airport and a third runway at Sea-Tac and that the third runway shall be authorized
by April 1, 1996:
a. Unless shown through an environmental assessment, which shall include financial and market feasibility
, Studies, that a supplemental site is feasible and can eliminate the need for the third runway; and
b. After demand management and system management programs are pursued and achieved, or determined
to be infeasible, based on independent evaluation; and
¢. When noise reduction performance objectives are scheduled pursued and achieved based on
independent evaluation, and based on measurement ofreal noise impacts.”
In October 1994, the Executive Board ofthe PSRC determined that within the meaning ofthe Resolution
there was no "feasible" site for a major supplemental airport that could eliminate the need for the third
. runway. See Resolution EB-94-01. It was the Panel's responsibility to make "independent evaluations” to
determine whether the demand/system management and noise conditions ofthe Resolution had been
satisfied and, hence, whether the PSRC should authorize construction ofthe thirdTunway.
After conducting several rounds ofhearings on Demand/System Management Issues, the Panel concluded
in December 1995 that within the narrow meaning ofthe Resolution, the demand andsystem
management programs that had been presented to Panel (including "high-speed" rail, congestion pricing
and, gate controls) were not "feasible’ and, therefore, that this condition ofthe Resolution had been
satisfied. We stress, however, that we did not find "high speed” rail (or interim improvements
in sxisiing
rail service), congestion pricing or gate controls to be infeasible in the
sense that they could not be
reaiized or were unworthy ofpursuit. In fact, based
upon the extensive evidence that was offered to us, it
is apparent to the Panel that acoherent, intermodal, cost-effective and environmentally
sensitive regionai
plan for accommodating the rapidly growing need for transportation infrastructure in the Pacific
Northwest
would include interimimprovements ofthe existing rail service in anticipation ofthe construction ofa
high speed rail system in the Portland-Seattle-Vancouver corridor, and the introduction
maeat28Sven designed to improve the efficiency ofuse ofscarce airport capacity. The Panel'sconsideration o ofregulatory
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Demand/System Management Issues is laid out in three separate orders: the February 24, 1995
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Preliminary Order on Demand/System Management Issues; the July 27, 1995 Final Phase I Order on
Demand/System Management Issues; and the December 8, 1995 Final Order on Phase 11
Demand/System Management Issues.
As a result ofthese two determinations, the only remaining condition for PSRC authorization ofthe third
runway project has been the noise impact reduction condition established by the Resolution.
Throughout our consideration ofNoise Issue, the Port, the Airport Communities Coalition ("ACC") and
the Regional Commission on Airport Affairs ("RCAA") have participated actively. They offered the Panel
volumes of evidence and distinguished expert testimony on the difficult questions posed by the
Resolution. We received thousands of pages of noise measurements, analysis, and interpretation, and
many informative statements ofposition from the Port, the ACC and the RCAA, as well as from the
FAA, the Airport Noise Group, the Pork Patrol, Air Washington and many individual members ofthe
public. The lead witnesses for the Port were Dianne Summerhays, from the Port's staff, and Paul
Dunholter, a noise expert with Mestre Greve Associates. The Port has, from time to time, called upon
other members ofits staff and outside experts to support its position. The ACC has offered the expert
testimony of Sanford Fidell ofBolt Beranek and Newman Systems and Technologies, and the RCAA has
offered exert testimony by Alice Suter.
We held our first round of hearings on Noise Issues in August 1994, and on September 22, 1994 the
Panel issued a "Procedural Order." We summarized the Resolution, the Implementation Steps and the
MOU in the Procedural Order, and ther acknowledged "that questions have been raised" about the scope
ofthe Panel's inquiry on Noise Issues. As a result, we announced that we would consider Noise Issues in
two phases. In Phase 1, the Panel would address three distinct questions:
Has the Panel been asked to determine- whether the goals ofthe- Noise Budget and the Nighttime
Limitations Program, if achieved, would produce a significant reduction in real noise impacts
on-the-ground?
If so, would achievement ofthe noise reduction performance objectives ofthe Noise Budget and
Nighttime Limitations Program produce a significant reduction in real noise impacts on-the- ground"?
Is the Noise Validation Methodology proposed by the Port a reliable method for determining, on the basis
ofmeasurements of actual on-the-ground noise using the existing noise monitoring system at Sea-Tac,
whether the noise reduction performance objectives ofthe Noise Budget and Nighttime Limitations
Program have been achieved? 3
If the Panel determined, in its Phase I decision, that the Noise Validation Methodology proposed by the
Port is a reliable method for determining whether appropriate noise reduction performance objectives
have been met, the Panel would turn in Phase II of its deliberations to the question ofwhether the Port
had demonstrated that it had achieved the noise reduction required by the Resolution. We noted in the
September 1994 Procedural Order that the Port has the burden of showing the Panel that it has satisfied
the noise reduction performance objectives imposed by the
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Resolution. Our Procedural Order was accompanied by extensive requests for information from the Port,
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the FAA and the public.
We returned to Seattle in December 1994 for two days of hearings, including an extended evening
session near the Airport devoted to testimony from residents ofthe affected communities. We then issued
our January 9, 1995 Order on Phase I Noise Issues. In our January 1995 Order, we summarized what we
consider to be our responsibility under the Resolution with respect to the reduction in noise impacts that
must be shown before the PSRC should approve construction of a third runway at the Airport. We held
that to meet its burden under the Resolution as we interpret it, "the Port must offer us reliable evidence,
based upon actual measurements ofon-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." As we said then, "the POS must establish that through whatever means, it has reduced the
impact of on-the-ground noise in a way that residents ofthe affected communities could appreciate.”
We noted, however, that because the Resolution contemplates that objective measurements of
on-the-ground noise should be used, the Part would not be required to conduct surveys of residents in the
affected communities to ascertain their subjective perceptions of Airport noise, even though such survey
results could provide useful information to the Port, the public and this Panel. We recognized that the
Resolution does not require the Port to reduce Airport noise to levels "acceptable" to the residents ofthe
surrounding communities, but rather requires only that the Port achieve a significant reduction in the real
noise impacts. We observed that "[bJusy 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 'acceptabie.' "
Finally, both during the December 1994 hearings and in our January 1995 Noise Order, we cautioned the
- particularly the noise impacts - that might occur if a third runway were
. public that "the con- sequences
built at the Airport" were outside our jurisdiction. As we put it then, "this Panel cannot and will not
undertake a review ofthe potential environmental consequences ofbuilding 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."
In anticipation of later hearings. in our January 1995 Noise Order we determined (a) that a showing that
the Port had performed its obligations under the Noise Mediation Agreement was necessary, but not
sufficient, to show compliance with the Resclution; {b} that the Noise Validation Method then proposed
by the Port was not a valid method of establishing the required reduction in noise impacts, and (c) thai
1993 should be used as the "base year" for purposes ofthe measuring whether the reduction in noise
impacts required by the Resolution has been achieved (because nothing in the Resolution spoke to
reductions in noise impacts that had already been achieved), but that the significance ofthe 1993-1996
data would ‘be best understood in the context of as much earlier data as the Port can make available to
us.’
We said that we would address three sets of subsidiary questions before resolving whether the Port had
met its burden: "(a) what measures of noise impacts should be used (that is, what noise ‘metrics’ should be
selected), (b) where should the measurements ofnoise be made, and (c) how much reduction in noise, by
these measures, must be achieved, and over what time period?" We recognized that ofthese, the
articulation ofthe required reduction in noise impacts presents "the
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to this
most difficult question." We did not presuppose that we could provide a satisfactory answer
Noise
question without the benefit of input from the Port and the community. So, in our January 1995
Order, we asked the Port to "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 Port has achieved
the required reduction."
Our January 1995 Noise Order led to a useful discussion ofnoise metrics that could be used to
supplement the information provided by DNL and precipitated the collection of on-the-ground noise
that better
measurements by the Port at six supplemental monitoring sites, farther out from the Airport,
represented significant portions ofthe affected population. In addition, the ACC subsequently submitted
usefulness of survey data, the ACC
new information. Taking up the Panel's suggestion about the potential
commissioned Dr. Fidell to conduct a social survey to determine whether residents ofthe affected
communities had perceived an improvement in their noise environment. Dr. Fidell conducted a telephone
affected by Sea-Tac-related noise.
survey of over 1,400 residents in six neighborhoods
When we reconvened in May 1995, the Port did not provide us, as we had asked that it should, with any
workable standard that we could use to assess whether the reduction in noise impacts is adequate to
the
demonstrate compliance with the Resolution. We were, as a result, unable to complete "Phase I" of
hearings on Noise Issues with a clear understanding ofhow the Port or the community advocates thought
noise or the information about
we should interpret the voluminous measurements of "on-the ground"
noise mitigation efforts that we had asked the Port to provide to us. To accommodate the Port's schedule,
in
we called for a preliminary round of hearings on Phase 11" Noise Issues
November 1995 that was focused upon the question ofwhat standard the Panel should use to make its
decision and how the accumulating information about noise levels and mitigation efforts should be
interpreted for Purposes Ofresolving whether the Port had satisfied its burden under the Resolution.
Following those hearings, we issued on December 18, 1995, our Preliminary Order on Phase II Noise
issues.
We noted in our December 1995 Noise Crder that these hearings had led to a resolution ofthe first two
questions we had posed for Phase II: There was no significant dispute about what noise measures should
be compiled or where the measurements ofnoise should be made. The most difficult, third question,
however, remained controversial: "How much reduction in noise, by these measures, must be achieved,
the
and over what time period?" The Panel was unwilling to accept the standard proposed by the Port or
standard proposed by the ACC. We noted that the selection of either ofthose competing standards for
judging compliance with the Resolution would itself determine the outcome ofthese proceedings.
We felt strongly that it would be premature to decide then whether the Port had met its obligation under
the Resolution and said that we would not make that determination until we had reviewed all the data to
be offered to us early this year on reductions in noise impacts from 1993 through 1995 and on reductions
in noise impacts following the 1990 Noise Mediation Agreement and leading up to the enactment ofthe
Resolution in 1993.
In anticipation of a final round ofhearings in February 1996, we provided some guidelines for what the
Port should show in its "Compliance Report.' We acknowledged that, as both the Port and the ACC had
recognized during the course ofthe hearings, ultimately the Panel would have to rely upon our ‘best
professional judgment taken as a whole, the pattern
... to determine whether,
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[PAGE 5]
ofchange in noise impacts is sufficient, in our judgment, to meet the requirements ofthe Resolution." We
realized that the PSRC General Assembly, in adopting Resolution A-93-03, was seeking an impartial,
objective assessment of a complex technical question. We said that, while we have always understood
that our decision would have a ‘social or political character," we have felt strongly that "our exercise of
judgment should reflect the best insights we can gain from established scientific sources about the
significance of changes in various noise metrics as indicators of changes in the impact of noise on the
people in the communities surrounding the Airport."
We asked the Port, and the community advocates, to address the following essential issues in written
Position Statements:
‘What reductions in on-the-ground noise impacts are shown by the various measurements and evidence
compiled by the Port?
How should the Panel interpret the significance ofthe reductions in noise impacts shown by the Port?
Why should the Panel find that the noise reduction condition established by the PSRC's Resolution has
been satisfied?
The Port responded to our December 1995 Noise Order by compiling- and distributing a vast array of
noise measurements and related information about its noise abatement and noise mitigation program. In
its Position Statement, which was supported by the expert testimony ofPaul Dunhoiter, the Port argued
that the Panel shouid find that it had satisfied the requirements ofthe Resolution because, based upon the
measurements of noise and modeling assumptions used by the Port, thousands of people no longer live in
areas judged by the FAA to be incompatible with residential use; thousands of people are no longer
"highly annoyed" by aircraft noise; high and medium speech interference has been reduced; the potential
for awakenings re- suiting from loud aircraft events has been reduced; and thousands of homes have been
relocated or insulated. In fact, the Port urged the Panel to conclude that its standard had been met
"without a detailed review ofthe data" because noise "must have been" reduced because noisy planes
have been greatly reduced overall and virtually eliminated at night; because the insulation ofhomes and
schools has been "aggressively pursued and achieved," and because people outside the Port have said that
its noise programs have. been successful.
The ACC submitted an opposing Position Statement, based upon the expert testimony ofDr. Fidel, that
made three principal assertions: (i) that the estimates of population benefits used by the Port were not
reliable because the tools used to derive them were not sufficiently precise to accurately predict benefits
from small changes in noise levels; (ii) that, in any event, the reductions in noise relied upon by the Port
were not
"significant' in the sense that they could be appreciated as reductions in noise impacts for the affected
populations; and (iii) that the Port could have scheduled, pursued and achieved a "meaningful" reduction
in noise impacts if it had not rested upon the Noise Mediation Agreement. The RCAA also submitted an
opposing Position Statement, and many members ofthe public wrote to the Panel to express their view
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that the Port had not reduced the impact of airport noise on their communities. Air Washington submitted
a statement in support ofthe Port.
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FINDINGS AND CONCLUSIONS (BY THE MAJORITY)
Because this has been a lengthy and complex proceeding, we believe it may be useful to set forth our
reasoning and the technical bases for our conclusions. Our findings and conclusions follow the general
structural framework ofthe Port's argument.
Tn brief, the Port contends (a) that the overall noise level at the Airport has shown a consistent downward
trend since 1989/1990, and has continued to decline (albeit at a lesser rate) since 1993; (b) that it has
complied with the 1990 Noise Mediation Agreement with respect to both noise abatement and noise
mitigation programs; {c) that the appropriate base year for comparative purposes should be 1989/1990
(or, alternatively, 1992), rather than 1993, the year Resolution A-93-03 was adopted; (d) that by a variety
ofnoise metrics, the Port has shown reductions in the actual, measured on-the-ground A-weighted sound
levels produced by the Airport since 1989/1990, 1992 and 1993; (e) that those reductions translate,
through a modeling and estimation process, into reductions in speech interference, sleep disruption,
number ofpeople "highly annoyed" by airport noise, and other "real noise impacts” on the ground, and (t)
that the change in 'noise impacts" can be translated, in turn, into reliable estimates ofthousands ofpeople
who have received non- trivial benefits from the noise reductions. Proceeding from that logic, the Port
. proposed the following standard for our decision:
Compliance with Resolution A-93-03 will be found ifthe entire record of reductions, taken as a whole,
shows a pattern of reductions for several thousand people, counting for each measure only people for
Whom the reduction is neither inappreciable nor meaningless. The determination will focus on the
reduction in noise impacts from 1993, but will not ignore improvements achieved before Resolution
A-93-03 was enacted.
At the Panel's request, -the Port measured changes in noise with two metrics in addition to DNL
(Day/Night Average Sound Level), an overall measure of daily A-weighted sound levels, which weights
nighttime noise more heavily than daytime noise and is commonly used in the industry to assess the total
level of airport noise. They are SEL (Sound Exposure Level), a standard measure ofthe level and
duration of single noise events, e.g., an aircraft flyover, and TA (Time Above), a standard measure ofthe
total time in seconds, minutes, or hours that aircraft noise exceeds a 65, 75, or 85 dB level in a 24-hour
period. Together with changes in the number and distribution of aircraft operations, these metrics provide
DNL alone. The
a more complete picture of changes in the airport noise environment than is given by
Port also reported the progress of its noise mitigation (building insulation) programs.
The Port has presented its noise data and conducted its analysis on the basis ofthe actual number of
operations at Sea- Tac Airport and the specific fleet mix of aircraft serving the Airport during the relevant
time period. Air carriers account for almost 60 percent of operations at the Airport (e.g., 54.0 percent in
1989/1990, and 58.5 percent in 1995), while commuter airlines represent about 40 percent (42.6 percent
in 1989/1990, and 38.7 percent in 1995). Air carrier operations have
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been increasing, and total operations at Sea-Tac Airport have fluctuated over the past eight
years as
follows:
TOTAL AIRCRAFT OPERATIONS SEA-TAC AIRPORT, CY 1988-1995 (IN THOUSANDS)
YEAR 1988 1989 [89/90* [1990 [1991 [1992 [1993 |1994 1995
TOTAL |
OPERA- 316 335 354 355 339 346 339 387
TIONS 353
i
AIR i
Hirer
CARRIER
177 182 Free \O med 193 187 196
OPERA- 200 212 226
TIONS i
|
i
“Operations for combined 1989/1990 base "year," per Port Compliance Report.
Source: Sea-Tac International Airport, Traffic and Operations Report
In some cases, the Panel's request for time-series data on the various noise metrics required the Port to
back-calculate certain airport data. For example, the Port calculated DNL
- values for earlier periods using the fleet mix at the time and the aircraft SEL data measured in 1995 at the
11 permanent Remote Monitoring Station ("RMS") sites and the six supplemental monitoring sites.
The Panel's task under Resolution A-93-03 is to evaluate the result.,; of, first, the Port's noise abatement
efforts (the impact of reductions in aircraft noise), and second, the Port's noise mitigation
programs (the
impact ofbuilding insulation). The Resolution itself speaks to overall reduction of "real noise impacts"
and the Port has presented a substantial body ofinformation on its efforts with respect to both noise
abatement and mitigation. Accordingly, we have taken both aspects ofnoise control - abatement and
mitigation -- into account in our assessment ofthe reduction of noise impacts.
We address the threshold points first, including the direction of change in noise levels since 1993, the
Port's compliance with the Noise Mediation Agreement, and the issue ofthe base year; turn next to our
evaluation ofthe results ofthe Port's actions with respect to (i) noise abatement and (ii) noise mitigation;
discuss the concept of "meaningful" and "reasonable" reductions in noise-, then summarize our findings
with respect to the overall reduction in noise impact.-, the Port has "scheduled, pursued, and achieved."
1. OVERALL DIRECTION OF CHANGE
As a result ofthe abatement and mitigation programs instituted by the Port under the 1990 Noise
Mediation Agreement, the general direction of aircraft noise levels (measured objectively by noise
monitors) has been downward since the PSRC General Assembly enacted Resolution A-93-03 in April
1993. The amount of change may be small, but it is not zero. When we rendered our January 1995 Noise
Order, however, the Panel determined that the Port had the burden of showing that the reductions in
noise impacts were "significant" or "meaningful," we held that some reductions, while desirable and
beneficial, might be too small to be sufficient to satisfy the Resolution. Accordingly, we find that the
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the mere existence of a slight
noise reduction condition ofResolution A-93-03 is not satisfied by
downward trend in DNL and SEL since 1993.
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II. COMPLIANCE WITH THE NOISE MEDIATION AGREEMENT
(NMA" or
Throughout this proceeding, the Port has relied on the. 1990 Noise Mediation Agreement
was the
"Agreement") as the cornerstone of its noise abatement and mitigation programs. The Agreement
the Noise
culmination of a long public process and includes many important components (principally
It was in 1990, an
Budget, the Nighttime Limitations Program and the Noise Remedy Program,,).
reduce the adverse environmental impacts
important milestone in the use of Stage 2 aircraft restrictions to
numbers of residents were
of airport operations. The Port was aware, however, that substantial
unsatisfied with the noise mediation process and the results it produced; many were extremely upset
Four Post Plan also introduced a
when, hard on the hells ofthe Agreement, the FAA's adoption ofthe
there has been vigorous
major realignment of flight tracks (and resulting noise impacts). In addition,
that many citizens apparently believe
opposition to the prospect of a third runway in the face ofpromises
In light ofthat ongoing history ofvocal opposition and
were made when the second runway was built.
A-93-03 in April 1993 should have served
concern about airport noise, the enactment ofResolution
its programmatic obligations
notice to the Port that it would not only be held accountable for meeting
that its noise programs were, in fact,
under the Noise Mediation Agreement, but would also have to show
reductions in noise impacts.
producing results in the form of meaningful, measurable, on-the-ground
stated that compliance with the Port's
‘Pursuant to the Resolution, the Panel's January 1995 Noise Order
of satisfying Resolution
obligations under the Agreement was a necessary, but not sufficient, element
A-93- 03.
whether the Port is currenily
We have reviewed the Noise Mediation Agreement in detail, to ascertain
the Noise Budget, the
satisfying the noise abatement and mitigation commitments it made under
other elements ofthe Agreement.
Nighttime Limitations Program, the Noise Remedy Program, and the
of 3.4 dB at the eleven permanent
With respect to the Noise Budget, given a measured reduction in DNL
the Budget have thus far
monitoring sites as ofthe end of 1995, we can be Confident that the goalsof
better than the stated goal for 1996
been met. The 3.4 dB reduction realized by 1995 is already 1.8 dB
ofthe Noise Budget
and is only 1.0 dB under the goal for 2001. According to the Port, the complexity
3
calculations apparently also encouraged certain airlines to opt for the simpler phased Stage
conversion option, which we believe to be a plus.
also requested
In connection with the Noise Budget, the PSRC Executive Board's Implementation Steps
which is used to
the Panel to review the validity ofthe Port's Noise Validation Method ("NVM")
We find that the NVMis a
translate measured DNL into the ANEL metric used in the Noise Budget.
of actual
sufficiently reliable method for purposes of determining, on the basis ofmeasurements
in the
on-the-ground noise, whether the Port has met the current noise reduction objectives (expressed
the 1995/1996 goal for
ANEL metric) ofthe Noise Budget, but we reach that finding only because
convinced that the ANEL goal
reduction in ANEL has been exceeded by more than a decibel. We are not
of aircraft operations; the change
for the year 2001 will be achieved, because ofthe growth in the number
in the conversion to
in DNL by 2001 may be considerably smailer, thus necessitating greater accuracy
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ANFEL We find that the Port's Noise Validation Method would only be a reliable method for determining
whether the firture ANEL goals have been met if it is revised to incorporate the input from the six
supplemental monitoring sites, as indicated
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in our January 9,1995 Noise Order, and any additional monitoring sites the Port may establish, with a full
accounting for statistical uncertainty in the measured data at all sites.
With respect to the Nighttime Limitation Program, the aircraft operation data compiled by the Port show
that its current goals have been met. We note that the number of exemptions is small and the number of
variances issued has dropped substantially over the past few years. The Port's expressed attitude about
continuing to minimize Stage 2 nighttime operations is encouraging.
Most ofthe elements in the Ground Noise Control Program have also been accomplished. Power backs
have been prohibited and are not occurring. The need for use of auxiliary power units has been reduced.
The Port is on record that it will pursue a "hush house' if an additional maintenance base is developed at
the Airport. We did not hear, however, about actions to reduce reverse-thrust noise upon aircraft landing,
as stipulated in the Noise Mediation Agreement.
We find that the improvements to the Duwamish/Elliott Day Corridor Noise Abatement Procedures
anticipated in the Noise Mediation Agreement have not been fully developed or implemented, especially
with regard to periods of "low activity" as called for in the Agreement. We also note that the current
nighttime departure corridors over Elliott Bay/Puget Sound have a low compliance rate.
The Moise Management System component has been implemented. There is some question about the
status ofthe program to Control Noise from Most Annoying Operations, which is intended to "control or
eliminate particular single event operations that occur on a continuing basis and that are the object of
community complaints.” That program has three elements: (i) improvement ofthe Port's Aircraft Noise
Hotline procedures to cross-check noise complaints; (ii) use ofthe Noise Management System, and/or
assistance from the FAA to identify the specific operation or event that prompted the complaints; and
(iii) a commitment that the Port will contact the airline or the FAA "to make the parties aware ofthe
specific noise concern and to attempt to reach a solution." From the record before us, it appears that the
Port is carrying oui that commitment with respect to initial departure only; in addition, it is not clear how
cooperative the airlines and the FAA have been in taking action to adjust or discontinue the
operations/events that provoke complaints, or how effective the program has been in actually conirolling
or eliminating such operations and events.
Turning to the NMA's Noise Remedy/Mitigation Program, our review indicates that, with the exception
ofthe insulation of public buildings (most notably public schools in the Highline School District), most of
the Port's essential milestones have been reached thus far, and additional mitigation has been scheduled
and pursue as described below.
The planned Acquisition/Relocation Program, a major element ofthe Noise Remedy Program, was
largely completed by 1993; the Port purchased the last few properties by 1995, accomplishing a total
buy-out of some 1,400 properties in the most severely noise impacted areas.
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Prior to the NMA, the Port was insulating 175 houses a year. At that rate, it would have taken more than
50 years (to the year 2040) to complete the insulation ofthe 10,000 homes now deemed eligible for
insulation treatment. The Residential Insulation Program adopted as pari ofthe NMA called for the Port
to insulate 350 houses per year, at that rate it would still have taken about 27 years to complete the
needed
work. In mid-1993, the Port greatly accelerated the
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residential program, and it is now proceeding rapidly (at a rate of about 110 homes per month). By
December 1995, the Port had insulated 3,647 houses.
The Audit Procedures for the insulation program have been implemented. The Cost Share Program has
been replaced by the standardized insulation program, as approved in the 1993 Part 150 Update.
However, the Mobile Home Program has seen little activity, and we have not been told ofthe existence
ofthe report on possible mitigation actions for mobile homes called for in the Agreement. For reasons
thax are not entirely clear, there has also been relatively little activity with respect to the Transaction
Assistance Program. We are not convinced that the Port is pursuing this program as effectively as it
could.
Our chief concern with the Noise Remedy Program involves the insulation of sensitive-use public
buildings, including the public schools (where progress has been delayed due to an impasse with the
Highline Public School District). In addition, the Noise Mediation Agreement envisioned an insulation
program that would cover a broad range of public buildings; it called for the Port to "[expand [the]
existing program to provide insulation for additional types of public buildings (e.g., auditoriums, private
schools, churches, day care centers, libraries, etc.).! At present, this component is limited to insulation of
classrooms at Highline Community College, now underway, and pilot projects at two churches, one
private school, one condominium and one convalescent home. For reasons that are more fully discussed
below (in the section ofthe Decision dealing with noise mitigation actions), we find that the Port's
compliance with this portion of the Noise Remedy Program is incomplete.
Although the insulation of sensitive-use public buildings is a critical aspect of noise mitigation and we
have very serious concerns about the lack ofprogress in this area, we have concluded, on the basis ofthe
Port's successful efforts to meet or exceed the requirement; ofmost ofthe other abatement and
mitigation measures stipulated in the Agreement, that the Port is in substantial compliance with the Noise
Mediation Agreement. Accordingly, we find that, on balance, the Port has met its burden under the
Resolution to show that it is satisfying its basic obligations under the Agreement. We note that this
finding does not necessarily imply that the programs pursued under the Agreement have been effective in
reducing "real noise impacts."
11. APPROPRIATE BASE YEAR
For the reasons stated in our January 1995 Noise Order and reiterated during the hearings in May 1995,
the Panel found that it was appropriate to use 1993 as the base year for purposes of the noise reduction
condition imposed by Resolution A-93-03. The Resolution does not by its terms establish a base year, and
in the absence of any expression in the Resolution that the General Assembly itselfmeant to look to the
11 0f50
past for reductions in noise impacts, it would be highly irregular to interpret the Resolution to establish a
retrospective test. The Panel said, however, that we would consider improvements in noiseimpacts
achieved before the Resolution was enacted in assessing the significance ofthe reductions scheduled,
pursued and achieved since 1993.
The Port has consistently maintained that 1989/1990 - the "year" immediately preceding the Noise
Mediation Agreement - shouid be used as the base year for purposes of comparison. We have not
accepted this position. In its February 1996 Position Statement, however, the Port offered for the first
time a new argument that even ifthe Panel was correct when we concluded in January 1995 that the
Resolution should be interpreted to require a meaningful reduction in noise impacts
[PAGE 11]
after it was enacted, the Panel should have used 1992, rather than 1993, as the base
year because the
Resolution was passed in April 1993. By taking 1993 as the base year, the Port claimed, the Panel
gave it
no credit for improvements realized during 1993.
The Port contends that the consequences ofthe Panel's interpretation were magnified by the coincidence
of a significant but transitory reduction in operations at the Airport and a resulting drop in
airport-generated noise during 1993 - a distortion which was then compounded, the Port argues, by a
sizable increase in operations at the Airport in 1995. As a result of these aberrations, the Port maintains,
the use of 1993 as the base year for comparison with 1995 made it very difficult to show a significant
. change in noise impacts. Accordingly,
while reserving its claim that 1989/1990 is the proper base year, the Port urged the Panel to consider the
reductions in noise impacts achieved since 1992, rather than 1993. The ACC responded that the Port's
argument came too late, that the Port should have offered April-to-April, rather than calendar vear,
estimates (to reflect exactly the timing of enactment ofthe Resolution), and that in
any event, the changes
in noise impacts since 1992 relied upon by the Port are not sufficient to satisfy the requirements ofthe
Resolution.
We have examined the Port's new argument carefully. We find that, although total Airport operations
declined in 1993, air carrier operations did not -- and air carrier operations are the driving force behind
the noise generated at Sea-Tac. The air carriers account for the majority ofthe Airport's operations, and
the aircraft they use are noisier than commuter aircraft: 2 dB to 12 dB (SEL) louder on arrival, and
up to
23 dB (SEL) louder on departure. Air carrier operations have declined in only one ofthe past seven
years: 1991, not 1993. Decreases in air carrier operations do affect airport noise, but no such decrease
affected the Sea-Tac Airport noise levels in 1993. In addition, the sharp increase in carrier operations in
the first few months of 1995 (instigated by the introduction of Southwest Airlines’ new service)
subsequently settled back to levels more consistent with the long-term rate ofgrowth.
However, the Port's persistent objections to the selection of a 1993 base year (which were echoed by
some members ofthe PSRC's Executive Board), and our own serious concerns about the potential
distortions that could be introduced by the selection of short-term intervals for examination, have led us
to review Airport noise levels over the entire ten-year period from 1986 to 1995, using data provided by
the Port.* These data show that the 1989/1990 base period preferred by the Port was the single loudest
'year' in the past ten years, as measured by the Port's 11 permanent remote monitoring station (RMS)
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and the 1996 Port
sites and reported in the 1991 Noise Mediation Committee Technical Report
would exaggerate the
Compliance Report. Consequently, selecting 1989/1990 as the base period
long-term effects of noise abatement on the neighboring communities.
the Port, show a
During that ten-year interval, the sound level changes at the Airport, as reported by
and 2.8 dB
reduction in aircraft DNL of 0.9 dB since 1993, 2.3 dB since 1992, 3.4 dB since 1989/1990,
fluctuations in the
since 1986. The overall change since 1986 (-2.8 dB DNL) masks some substantial
sites in the
actual rate of change; there was no reduction in average DNL at the 11 permanent RMS
from 1993 to
five-year period between 1986 and 1991, for example, and there was very little change
1995.
*Data on aircraft DNL in 1987 was not available to the Panel.
[PAGE 12]
To avoid biasing our analysis by overstating or understating the trend in noise changes over time, we
of a base year --
have decided to take a comprehensive approach. We do not wish to permit the selection
to prejudice the outcome ofthis proceeding, and
a choice that is inevitably arbitrary in some respects --
and mitigation programs over all
we have therefore examined the results ofthe Port's noise abatement
three periods: since 1993, since 1992, and since 1989/1990.
Resolution was
As this Panel stated in the January 1995 Noise Order, "We are convinced that the
ofthe
intended to condition the approval ofthe third runway upon a showing that the noise impacts
evaluated all of
existing Airport have been reduced in a significant way." Accordingly, we have carefully
whether the Port has, in
the evidence presented to us, for each base-year period, in order to determine
reduction in real,
fact, successfully "scheduled, pursued, and achieved” a meaningful and perceptible
on-the-ground noise impacts for the people in the communities surrounding the Airport. We present our
ofthe
detailed evaluation below, reporting the specific results of our analytical work for the benefit
PSRC, the Port, the communities affected by airport noise, and other interested parties.
IV. EFFECTIVENESS OF NOISE ABATEMENT PROGRAMS
The Port argues that its noise data shown- reductions in actual, measured, on-the-ground A-weighted
and
sound levels are accurate; that the measured reductions can reliably be converted, through modeling
estimation, into reductions in numbers ofpeople "highly annoyed" by airport noise, speech interference,
be then converted
sleep disruption, incompatible land use, etc.; and that the change in "noise impacts" can
from the noise
into credible estimates that several thousand people have received non-trivial benefits
reductions, thus demonstrating that the
Port has successfully met the requirements ofthe Resolution.
The ACC has urged that the Panel reject the Port's claim to have achieved a significant or meaningful
reduction in noise impacts since 1993 for two related reasons: (i) the analytic tools used to derive the
from small
Port's estimates have not been shown to be accurate in measuring changes in noise impacts
have been
changes in noise levels; and (ii) the reported reductions in measured noise levels and impacts
the Airport.
too small to be appreciated by the residents ofthe communities surrounding
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Reliability ofEstimates
The Port presents various estimates ofthe changes in noise impacts associated with the measured and
computed changes in DNL, SEL, and TA since 1993, 1992, and 1989/1990, in terms of numbers of
people experiencing annoyance, sleep interference, sleep disturbance, and other on the-ground noise
impacts. These estimates are subject to several layers of potential measurement and estimation error: (i)
in the initial calculation ofthe chances in aircraft DNL based on measured SEL data from the permanent
and supplemental monitoring sites; (h) in the application ofthe revised dose-response Schultz Curve
recommended by FICON ("FICON Curve") to estimate noise impacts; and (iii) in the adjustment and
application ofthe Integrated Noise Model "(INM") to estimate DNL contours and the numbers of people
benefited by reductions in noise impacts.
The Panel acknowledged, when we requested the Port to expand its monitoring sites, to supplement its
DNL analysis with the additional SEL and TA metrics, and to document its estimates of changes in
on-the-ground noise impacts, that the process would "inevitably require the Port to
[PAGE 13]
oack-caiculate or otherwise estimate some ofthe required inputs” and that this "would introduce some
imprecision into the exercise."
We did not, however, excuse the Port from the burden of addressing the extent and impact ofthat
- imprecision. We expected the Port (i) to present information on confidence intervals to support the
statistical reliability of its data, (ii) to document the assumptions and adjustments it made when it applied
the FICON Curve and the INM to estimate changes in DNL contours, numbers of people benefited and
other noise impacts, and (iii) to perform sensitivity tests, where appropriate, to evaluate the effects of
those assumptions. In the December 18, 1995 letter that accompanied our Preliminary Order on Phase 11
Noise Issues, for example, we asked the Port to "clearly and completely document every assumption and
adjustment it has made in calibrating the INM as used in its Compliance Report.” We repeatedly
requested confidence intervals and sensitivity tests in the course ofthe hearings. The Port did not supply
that information.
in response to the Panel's questions at the February 1996 hearing, the Port presented some partial details
on the confidence intervals for its 0.9 dB reduction in aircraft DNL since 1993. The Port stated that, for
the DNL measurements at the permanent RMS sites, the 95 percent confidence intervals were plus or
minus 0.2 to 0.4 dB. At the supplemental monitoring sites, the intervals were much wider: "in the
neighborhood ofplus or minus 1.5 dB, according to the Port's noise consultant. In other words, the
actual change in aircraft DNL since 1993 (per the Port's permanent monitoring sites only)
may be as large
as - 1.3 dB Or as small as -0.5 dB; and the change in aircraft DNL at the supplemental sites is not known.
This risk ofDNL measurement error is a function of several factors: the possibility ofvery smail
inaccuracies in the measurement system calibration over time; the more important fact that noise impacts
can vary considerably with slight changes in topography and distance from the, noise source; the accuracy
with which the system can separate aircraft noise from other sources; and, for the supplemental
monitoring sites, the use of data from sample weeks rather than 365 days ofmeasurements to compute
measured DNL at the sites.
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The principal analytical tools the Port used to translate its measured DNL reductions into on-the-ground
noise impacts were the FICON Curve and the Integrated Noise Model.
The FICON Curve, based on the noise dose-response relationships reported from
many surveys, is an
accepted "model" or method, of estimating noise impacts on populations from changes in measured noise
levels (DNL). In making use ofthe FICON Curve, however, the Port did
not take account ofthe margin
of error inherent in the curve. The
surveys on which the FICON Curve is based are subject to two kinds
ofmeasurement error in the physical measurement ofthe noise (i.e., whether the instruments registered
the same levels of noise experienced by
the population), and error in the
survey reports. Green and Fidell address these issues in an article
accompanying the widely accepted 1991 update ofthe original Schultz Curve by Fidell, Barber and
Schultz.* Green and Fideil estimate that the measurement error in the noise variable is I
to 3 dB, and that
the measurement error in the survey reports translates into
a 4 dB range in the noise
* D. Green and S. Fidell, Variability in the CriterionJor ReportingAnnoyance in Community Noise
Surveys, J. Accous. Soc. Am. 89 [1], January 1991.
,
PAGE 14]
variable. They estimate that these errors, together, amount to approximately 5 d]B. In other
words, DNL
differences ofless than 5 dB fall within the FICON Curve's margin of
error and therefore cannot be used
to make reliable estimates of differences in the percentage ofthe population which is "highly
annoyed' by
aircraft noise impacts.
Neither the -0.9 dB DNL change reported at Sea-Tac since 1993,
nor the -2.3 dB or -3.4 dB DNL
changes since 1992 and 1989/1990, approaches the 5 dB margin of error in the FICON Curve. Thus, the
estimates ofthe population effects which the Port derived from the FICON Curve Thus, the
estimates of
the population effects which the Port derived from the FICON
curve are not statistically reliable. The
model is simply not sensitive enough to produce dependable estimates ofreductions in noise impacts
from
such small changes in DNL.
Another way to understand this point is to examine the 95
percent confidence interval around the FICON
Curve, which Fidell, Barber and Schultz (1991) calculate. Although the width of the confidence interval
varies along the Curve, at the mid-range ofthe FICON Curve, for
a given DL, the 95 percent confidence
interval is nearly 20 percentage points wide. For example, at a DNL of 70 dB
on the FICON Curve, we
can be 95 percent certain only that the percentage ofthe population "highly annoyed" by aircraft noise is
somewhere between 15 and 35 percent.
The Integrated Noise Model is a complex FAA-approved
computer model used to calculate the land
areas impacted by aircraft noise (DNL contours in square miles), and the corresponding numbers of
people affected by aircraft noise within various DNL contours. The INM is a standard analytical too], but
the outputs ofthe INM depend on the specific values the analyst assigns to the input
variables. Despite
the Panel's specific requests, the Port failed to supply detailed information
on the assumptions and
adjustments it used when it applied the INM to compute changes in (i) DNL contours and (ii) the
population adversely affected by noise, from the measured SEL data for each aircraft type. It was not
enough for the Port to present for the first time, at the final hearings in February 1996, tables comparing
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measured and modeled DNL differences at each Monitoring site, with no analysis ofthe potential effects
ofthese differences on the population estimates and noise impact reductions the Port had derived.
Without clear documentation of all the adjustments the Port made to its INM input files, it is very difficult
to assess the reliability ofthe Port's estimates ofreduced noise impacts and corresponding population
benefits.
Noise analysts frequently must make assumptions in running- the INM computer program or otherwise
estimating the impacts of noise exposure on an affected population. In such cases, one can use sensitivity
value or
tests, in turn, to evaluate how much a change (or a measurement error) in a key input
assumption might affect the outcome. The Port presented no reports on the results of any sensitivity tests
it may have conducted In short, we do not know what assumptions the Port used in this application ofthe
INM or how much difference it might have made ifthe Port bad decided to usea slightly different set of
assumptions to compute its estimated changes in noise impacts and benefits.
These various types ofmeasurement and estimation error can cascade through the modeling and
estimation process, compounding the uncertainty ofthe final results. Small changes in estimated noise
impacts may be a product ofthe degree of error incorporated in the modeling process, rather than any
actual change in on-the-ground noise impacts. Absent the kind ofinformation that would permit us to
independently assess the reliability ofthe Port's estimates, we are left with the possibility that the noise
impact results the Port is estimating may very well be smailer than the cumulative measurement error in
the Port's methodology.
PAGE 15]
Our concern about the propagation of error in the Port's analysis does not reflect a normative judgment
shat the Port made a mistake or did something wrong in its analysis {other
than its failure to document the uncertainty in its data and the effects of that uncertainty on its results).
Rather, our concern reflects (i) the fact that analytic tools like the FICON Curve cannot provide robust
sstimates ofthe population impacts ofthe small reductions in DNL that were measured by the Port, and,
its data, the INM
more specifically, (ii) the fact that the Port did not specify the confidence intervals on
inputs, assumptions, and adjustments it made, or the sensitivity test resuits that would allow us to place
reasonable confidence in the Port's conclusions about noise impacts.
The Port argues, with some force, that the Panel should at least accept the approximate magnitude ofthe
results it has derived even ifwe reject the appearance of precision as unjustified. The Port claims that in
order to control for the risk of error, it has systematicaily biased its assumptions and adjustments to
minimize the apparent reduction in noise levels, and associated noise impacts, over time. This claim,
however, is difficult to accept without a complete description ofthe actual assumptions and adjustments
the Port made. More persuasively, the Port emphasized that the direction and pattern of changes in noise
levels and noise impacts that it has estimated are consistent with the relatively reliable measurements
taken at the Port's permanent monitoring sites and with common understanding ofthe two underlying
phenomena that have caused the most significant changes in the Airport's noise environment in recent
at night, during the years
years: the dramatic reduction of Stage 2 aircraft operations, especially
1989/1990 to 1995, and the marked growth in Stage 3 aircraft operations since 1993.
The Port points out that one would expect, in these circumstances, to see a continuous reduction in DNL
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with a corresponding
over those years; a reduction in the loudest aircraft events, measured by SEL,
Above 65
reduction in average SEL and Time Above 85 dB; and, beginning in 1994, an increase in Time
14
dB caused by the increase in flight operations (now running at more, than 1,000 flights per day, up
the Port's noise measurements
percent from 1993). Since this is exactly the pattern that emerges from
should be
(and back-calculations), the Port argues that its analysis of noise benefits "makes sense" and
credited by the Panel. While these arguments have some intuitive appeal, they were ultimately not
benefits.
convincing, in light of our detailed analysis of the Port's noise metrics and estimated population
noise
We have examined with great care each ofthe Port's specific arguments about on-the- ground
impacts and its calculations as to numbers of people benefitted by noise reductions. Wherever possible,
find that the underlying data show no
we have reviewed and analyzed the underlying data. In general, we
serious internal inconsistencies across the various noise metrics; for purposes of analysis, therefore, we
reflective ofthe actual
accept the Port's DNL, SEL, and Time Above data as generally (if not precisely)
data
changes in fleet mix and pattern of operations at the Airport. The critical question is what those
actually demonstrate, in terms ofmeaningful or significant reductions in real on-the-ground noise impacts.
the
The Port urges us to accept its interpretation of the data with regard to noise impacts. The ACC and
RCAA urge us to reject that interpretation. We have conducted an independent evaluation, as Resolution
the
A-93-03 explicitly requires. We present, below, our analysis and findings with respect to each of
major types of "noise impacts" addressed in the Port's Compliance Report.
[PAGE 16]
Percentage Highly Annoyed
Noise impacts are often evaluated in terms of changes in the number and percentage ofpeople "highly
annoyed" by a given noise source. In its Compliance Report the Port estimated that some 28,000 people
of a total popuiation of250,000 to
were "highly annoyed" by Sea-Tac Airport noise in 1989/1990, out
reductions in
300,000 people within the 55 dB DNL contour at the time. The Port asserted that the
aircraft DNL at Sea-Tac have produced a 11 percent decrease since 1993 -- and a 33 percent decrease
since
since 1989/1990 -- in the overall number of people "highly annoyed" by aircraft noise: 2,100 fewer
1993, and 9,900 fewer since 1989/1990, by the Port's estimates.
the
At the end ofthe final day of the February 1996 hearing, in response to the Panel's questions about
fewer
basis for those statements, the Port supplied the following table to substantiate its estimates of
people "highly annoyed."
PORT ESTIMATES: PERCENTAGE OF PEOPLE HIGHLY ANNOYED
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'DNL CONTOUR BAND 1989/90 11993 [1995
75 dB and above
} 45 36 [34
70-75 dB 129 2 20
65-70dB 17 12 nn
60-65 dB io 6 l6
55-60-dB 's 3 13
‘OVERALL PERCENT HIGHLY ANNOYED 1 7 l6
(Note: The overall percentage highly annoyed reflects a weighted average ofthe number of people
affected by airport noise in each DNL contour band; there are
very few people in the 75 dB DNL
contour, but many in the 55, 60 and 65 dB contours. 1992 is not included because the Port supplied
no
estimates on percent highly annoyed in 1992.)
We were then able to trace the logic behind the claim. The Port had placed its reported changes
in aircraft
DNL on the FICON Curve, calculated a corresponding overall
percentage of people "highly annoyed" in
1989/1990, 1993, and 1995 9, 7, and 6 percent, respectively, ofthe population within the
55-dB-and-above DNL contour then multiplied those percentages by its INM population estimates
and
compared the results with the original estimate of 28,000 people "highly annoyed” in 1989/1990, in order
to arrive at its figure of 9,900 fewer people "highly annoyed" in 1995.
That would have been a positive benefit, ifwe could reasonably conclude that it had actually
occurred.
Unfortunately, the entire calculation was based on very small movements along the FICON Curve: a shift
of -0.9 dB DNL since 1993, and -3.4 dB DNL since 1989/1990, along
a curve that does not accurately
predict changes in annoyance for DNL changes of less than 5 dB. There is a very large potential for error
when one uses the FICON Curve to estimate the, percentage of "people benefited’ from
very small
reductions in DNL; as noted earlier, the 95 percent confidence interval is about 20
percentage points
wide. Because the percentage changes the Port computed in its table
-- the shifts from 9 to 7 to 6 percent
ofthe overall population -- have no solid basis, one cannot conclude that there has been
any change at all
since 1993 in the actual number or percentage of people highly annoyed’ by aircraft noise,
or more than
an insignificant change since 1989/1990.
[PAGE 17]
Consequently, we cannot find that the Port has demonstrated any significant "noise impact" benefits on
the basis of its "highly annoyed" population analysis. Contrary to the Port's assertions in the Compliance
Report, the actual data are, instead, consistent with the findings ofthe ACC's 1995 social survey that the
majority of residents do not perceive a reduction in annoyance due to aircraft noiseimpacts.
The ACC social survey results, covering six communities in the vicinity ofthe Airport, indicated
that (i)
people in the Sea- Tac area are generally more tolerant of aircraft noise than people elsewhere in the
country where such surveys have been done, and (ii) an average of 30 percent ofthe respondents were.
more annoyed by aircraft noise over the past two years (February 1993 to February 1995), while
an
average of 9 percent were less annoyed. The Port criticized the survey technique (which asked
respondents to remember a noise situation two years prior and to compare it to the current time period)
and offered expert testimony by Dr. Ward discounting the reliability of
memory. On review, we find the
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survey a useful device, conducted by a leading expert on such surveys. Because the technique differed
from the usual methodology of asking respondents to describe the
then-current situation at two different
times and then independently comparing the
answers (no such prior survey was available for the Sea-Tac
area), we accept the survey's results on the change in annoyance as illustrative rather than
definitive. We
note that the ACC's survey results are consistent with the relationship between
DNL and Percentage
Highly Annoyed expressed in the FICON Curve for noiseimpacts.
Loudest Aircraft: SEL Analysis
The Port also presents data on individual aircraft noise
events in terms of Sound Exposure Levels (SEL).
There has been a reduction in the highest-noise-level aircraft
events, as measured by the Port's SEL data
and the aircraft operational data for the changing fleet mix
at the Airport.
From 1993 to 1995, the total number of Stage 2 flight operations
at Sea-Tac declined from 132 per day
to 93. Moreover, by 1995 the majority ofthe remaining Stage
2 planes were F28s, which arc measurably
quieter (by 5-7 dB SEL) than the Stage 2 Boeing 727s that dominated the noise
profile in 1990 and were
still the dominant Stage 2 aircraft in 1993. At night, the
average number of Stage 2 operations dropped
from 20 in 1993 to 9 in 1995; only a handful remained by the
end of 1995 (due to the October 1995
deadline in the Nighttime Limitations Program).
In recent years, however, the change in
average SEL has been small. We find that the overallfleet-wide
average SEL reduction of2.0 dB since 1993 is too small to produce a meaningful change in
on-the-ground noise impacts, especially when coupled with more flight operations.
Further,any
assessment ofthe reliability of that figure is complicated, in
part, by the range ofvariation in measured
SEL values over various aircraft types and
even within individual aircraft categories. We also find that
there was relatively little reduction in the number ofpeak aircraft
noise events with a SEL over 95 dB
(averaged over the 11 RMS sites) from 1993 to 1995.
Moreover, the Port's data show an increase since 1993 in aircraft noise events with
an average SEL over
85 dB at the 11 RMS sites (with only
a slight decrease at the supplemental sites). There has also been
an
increase in the number of aircraft events with an
average SEL over 75 dB at both sets of sites. The Port
did not supply 1992 average SEL data for the Panel'sanalysis.
[PAGE 18]
Since 1989/1990, there has been an overall 4.5 dB reduction in
average SEL for individual aircraft
events. ‘Mat change, which reflects the early phase-out of Stage 2 aircraft
at Sea- Tac, would appear to
be "significant" and "appreciable," in the
sense that people should be able to notice a difference ofthat
magnitude and perceive some benefit. The extent to which residents actually do
perceive a difference of
4.5 dB SEL in the average level of individual aircraft
events over the course of a six-year period
may be
tempered, however, by the unreliability ofmemory (as the Port noted in its criticism of the social
and by the countervailing effects ofan increase in the number survey),
ofdaily aircraft operations over the same
period.
Federal regulations require the phase-out of all Stage 2 operations
by 2001. The Port produced earlier
benefits for the Puget Sound Region by accelerating the phase-out of
Stage 2 aircraft in the early 1990s;
86 percent ofthe fleet was Stage 3 by 1995. In effect, residents obtaingdshe
benefits of the drop in peak
19 of 50
SEL (aircraft events above 95 dB) sooner than they otherwise would have, as Sea-Tac outpaced the
national phase-out of Stage 2 aircraft. While that early improvement was certainly beneficial, we find that
the gains the Port achieved (reflected in reductions in average SEL) arc now being eroded by the growth
in operations, as the following evaluation ofthe Time Above (TA) data indicates.
Speech and Activity Interference: Analysis of Time Above
One ofthe most useful and illuminating- ways to assess changes in noise impacts is the Time Above (TA)
metric. The Port uses this measure to estimate chances in speech and activity interference (and
corresponding numbers of people benefited) from data on the changes in daytime TA 85, 75 and 65 dB
outdoors, and changes in daytime TA 60 dB and 45 dB indoors. While the TA metric is measured directly
from the Port's RMS and supplemental monitoring sites, the Port's estimates of the number of peoplebenefited
must be viewed with the same cautions raised previously about the
accuracy ofthe
INM-estimated population data.
Because the Port provided no Time Above data for 1992, our analysis is limited to the 19931995 and
1989/1990-1995 time periods. Except where noted below, the Port presented data on TA "per day" based
on a 15-hour daytime "day."
We evaluated the significance ofthe reported reductions in Time Above in terms ofminutes
per day, as
well as percent change. For example, in the 1993-1995 time period, the large percentage reductions in
daytime TA 85 that the Port cites in its Compliance Report actually represent decreases of less than two
minutes per day in noise exposure above 85 dB, while the small percentage increases shown in TA 65
amount to as much as an additional 44 minutes per day of noise exposure above 65 dB.
When we examined the longer 1989/1990-1995 intervals we found a similar pattern. The
average daytime
Time Above 85 dB at the reported monitoring- sites fell from about five and a half minutes a day in
1989/1990, to just under two minutes a day in 1995. The average Time Above 65 dB remained much the
same: 2 hours and 53 minutes in 1989/1990, compared to 2 hours and 38 minutes six years later.
It is difficult to conclude that such small reductions in average TA 85 constitute a meaningful reduction in
"real noise impacts.." How much weight should one give to the decreases in Time Above 85, in
evaluating population exposure to aircraft noise? Removing a large share ofthe loudest
[PAGE 19]
aircraft noise does make a difference in on-the-ground noise
impacts. But recent increases in Time Above 65 dB are now partially offsetting the reduction in the peak
aircraft noise (TA 85).If one takes the "equal energy principle" at face value -- a ten to one noise-energy
tradeoff for a 10 dB difference one hundred to one for a 20 dB difference, etc. -- then as of 1995, with
respect to operations at Sea-Tac, the decreases in TA 85 still outweigh the increases in TA 65, implying
an overall net benefit (as the small but continuing reduction in DNL suggests). We view that tradeoffwith
some circumspection, however, especially as TA 65 grows further into the "several hours per day" range.
At that point, the real-world relationship between aircraft noise levels and number of operations comes
into play. The pattern of aircraft noise at a site in the community has fewer
very loud peaks but becomes
far more continuous, and a steady stream of aircraft noise above 65 dB has noise impacts of its own.
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For the three RMS sites where the Port presented 24-hour (rather than daytime)
measured TA data from
the Port's noise monitoring system - RMS sites 5, 10, and II
-- the Time Above 65 dB in 1995 was 5
hours per day at RMS 5; 3 hours and 51 minutes
per day at RMS 10; and 9 hours and 49 minutes per day
at RMS 11. At all three sites, Time-Above 65 dB is
now higher than it was in 1993, and at RMS 11, TA
65 is also higher than it was in 1989/1990.
Moreover, at one site -- RMS I 1 -- TA 85 was no higher in 1995 than it was in 1993. The increase in TA
85 from 9.5 to 10.4 minutes
per day at RMS 11 indicates an increase in the loudest aircraft events,
perhaps as a result of increased aircraft around noise.
Our examination ofthe TA data suggests that the Port
may have already obtained most ofthe net benefit
it can expect from the reductions in TA 85 produced by its
current noise abatement programs. It appears
to the majority ofthe Panel that the Airport
may have reached a plateau in net noise reduction or will do
so shortly, because TA 65 is now increasing steadily, and the earlier downward trend in TA
75 has
apparently bottomed out as well. With the rising number of flight operations, the number ofminutes (or
hours) of Time Above both 65 dB and 75 dB is likely to -rise in future years, soon overtaking- the real
benefits ofthe Port's reductions in TA 85.
We note that Time Above 65 dB - not to mention 75 dB
- does more than merely cause "low levels" of
speech interference; it disrupts a wide variety of everyday activities (relaxation, thinking, reading,
learning, and listening) and is correlated with increased levels of stress, tension, and annoyance. The Port
cites the 1992 FICON Report discounting such effects; however, since that FICON
Report was issued, a
considerable body of medical literature has been developed, documenting the adverse effects
of exposure
to noise levels in the 65 to 75 dB range, including psychological distress, loss of concentration
and
reading comprehension, and other physiological effects. In short, increases in outdoor TA 65 can produce
serious on-the- ground noise impacts.
We also evaluated the Port's estimates of indoor speech and activity effects based
on changes in interior
TA 45 in single- family residences. The Port's data
support a finding of substantial improvement in
interior TA 45 for insulated buildings with the windows shut, but that is primarily
a function of the
insulation, not a result ofimprovements in the outdoor TA. (The data results do demonstrate the
significance of achieving an average A-weighted sound level reduction of 7 dB for insulated houses, with
windows closed.) For the open-window case, however, it appears that interior TA 45 -- a benchmark for
the threshold of speech interference -- has increased, based
on the trends in the outdoor TA 75 and TA
65. The Port did not specifically show the interior, open-window TA 45 dB data.
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Changes in classroom speech and activity interference were assessed using interior TA60 and TA 45. In
examining the underlying data, we find that the large percentage improvements the Port shows in
‘medium level" speech interference from 1993 to 1995 amount to actual reductions of
just two to three
minutes per day. The data also show almost no improvement in the
amount oftime above the 45 dB
threshold for speech interference. Most important, our analysis revealed the striking
fact that for the four
schools the Port cites, even with the windows closed, the interior noise levels
are above the threshold for
speech interference (45 dB) for an hour to an hour and a halfper day.
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Once again, marked improvement is shown when insulation is added. When the Port adjusts its estimates
to reflect a 5 dB reduction in A-weighted sound level due to insulation, the number
of classroom hours above that threshold noise level of45 dB are cut in half - still disruptive to the
learning process, but much better. These results underscore the critical need for schoolinsulation,
because a continued increase in aircraft operations in the future will only increase the number ofminutes
(or hours) over the threshold for speech interference.
Nighttime Noise Improvements
The Port also presented data and analysis on the change in the potential for sleep disturbance. We note
that because the method of analysis is new and untested the Port's results should be viewed with caution,
especially in light ofthe concerns outlined above about the reliability of the Port's INM-estimated
population benefits. The method does seem plausible in its approach and its use ofthe USAF curve on
probability of awakenings.
The reported 1.9 dB reduction in the average SEL ofnighttime events since 1993 is not
a meaningful
indication of changes in real on-the ground noise impacts, and the reliability ofthat figure is complicated
by the range ofvariation in the measured SEL data across and within aircraft categories. The reported
decreases in nighttime L. in recent years are small as well: -0.9 dB since 1993, -1.9 dB since 1992. and
-3.6 dB since 1989/1990. It appears to the majority ofthe Panel that the small size of the reductions may
be due to a combination of three factors: (i) the increase in the number of nighttime flight operations; (ii)
the fact that the wide-body Stage 3 aircraft, with the exception of the Boeing 767, have the highest
A-weighted sound levels on arrival -- greater than a Stage 2 Boeing 727; and (iii) the fact that, on
departure, the wide-bodies and the hushkitted/reengined 727s and DC8s are within 3 to 6 dB (SEL) of
the Stage 2 Boeing 727. Although there are now far fewer Stage 2 flights at night, the total number of
nighttime flight operations is not declining. The Port's data show an average of 133 flights per night in
1989/1990, 120 per night in 1993, and 138 per night in 1995 (data on 1992 nighttime operations were
not reported).
The Port's analysis shows a modest decrease in the overall potential for awakenings since 1993, which is
attributed mostly to the home-insulation program (discussed later in this Decision). With the windows
closed, insulation does work. Our analysis ofthe data, however, shows an increase in the number of
potential awakenings for the open-window case, which suggests that the increase in totalnighttime
operations is overriding the decrease in average aircraft SEL produced by the nighttime Stage 2 phaseout.
Moreover, we are concerned about the Port's decision to use a 5 percent open-windows assumption in its
analysis (i.e., the Port estimated the overall rate of nighttime awakenings on the assumption that residents
keep their windows closed 95 percent ofthe time). We are not sure of
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the factual basis for that assumption, or the extent to which it may have affected the Port's results. No
sensitivity analysis was presented, although we would expect that the difference in noise exposure with
open v. closed windows has an important bearing on the rate ofnighttime awakenings.
The effectiveness ofthe Port's nighttime noise abatement programs is being undermined to
some degree
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by poor air-craft compliance rates on the North Flow Noise Abatement Departure Corridors. We
commend the Port for its actions in implementing these corridors; it is clear that such flight track
procedures can havea significant impact on population noise exposure. But they produce results only if
they are enforced. While compliance with the nighttime Corridor procedures is fairly high on initial
departure, we find that the compliance rates are unacceptably poor outside the immediate vicinity ofthe
Airport. In December 1995, for example, significant numbers of aircraft failed to comply with the North
Flow Corridors at night: 29 percent on the Elliott Bay Departure, 25 percent on the Puget Sound
Departure North, and 27 percent on the Puget Sound Departure South. For the third quarter of 1995,the
failure rates for those three Departure Corridors were 21 percent, 19
percent, and 40 percent,
respectively. By comparison, the noncompliance rates for the nighttime South Flow Puget Sound Arrival
Corridor were 1.4 percent in December 1995 and 0.6 percent in the third
quarter of 1995.
Primary responsibility for this problem rests with the FAA, which has operating authority over the more
distant sections ofthe Corridors. In light ofthe specific language in Resolution A-93-03 requesting the
FAA to do more to reduce the noise impacts associated with the Four Post Plan,
we find it troubling that
the FAA would hinder the Port's noise reduction efforts by failing to
enforce the existing abatement departure procedures. The Port and the residents ofthe Region deserve
better.
We are also concerned that Alaska Airlines has shifted its two nighttime Stage 2
cargo arrivals and
departures to Boeing Field ("King County International Airport" or 'KCIA') in -order to sidestep, rather
than comply with, the Port's nighttime limitations on Stage 2 flights - a move which,
we recognize, is
outside the Port's jurisdiction (but perhaps not outside its influence). Taking advantage of the fact that
KCIA is an unregulated general aviation airport, not subject to the controls that
govern commercial
airports, the carrier continues to operate these flights. These very loud aircraft events have generated
many complaints, and this action by Alaska Airlines weakens the effectiveness ofthe Port's Nighttime
Limitation Program.
In light ofthe small reductions in nighttime SEL and Leg, the greater likelihood of awakenings in
recent
years in the open- window case, and the factors undermining the Port's efforts to reduce nighttime noise
exposure, we do not find that the Port has made a convincing case that there is a significant overall
reduction in sleep disruption due to aircraft noise.
Airline decisions to shift Stage 2 aircraft operations out of the nighttime period to the "shoulders" ofthat
period -- that is, 8-10 p.m. and 7-8 am. -- also have implications with respect to noise impacts (the Port
has acknowledged the likelihood of such shifts in the timing of Stage 2 operations). The 8-10
p.m.
interval covers the bedtime hour for many children and the period of evening relaxation and early bedtime
for many adults. The Apogee survey ofpeople near Dallas/Ft. Worth Airport (which the RCAAsupplied
for the Panel's review) showed high levels of
annoyance with aircraft noise before 10:00 p.m., due to
interference with normal evening activities.
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Noise Contour Analysis
Another series ofmeasures presented by the Port relates to the "change in DNL land
use and population
impact.” The Port asserts that the population within the high noise contour (75 dB DNL) has now
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dropped from 3,100 to nearly zero. From the information we have seen, it is not clear that such a
reduction actually occurred in the stated 1993-1995 time frame (for example, the 1993 DNL contour map
shows virtually no residential land use within the 75 dB zone). Nevertheless, the ability to say that no one
is residing inside a DNL contour of 75 dB is an important marker for an abatement program; in keeping,
with our decision to include earlier time periods, we give the Port full credit for this accomplishment no
matter when it occurred.
Similarly, sizable reductions in the number ofpeople inside the 65 and 55 dB DNL contours are
important. The Port states that 8,000 fewer people are inside the 65 dB DNL contour since 1993, and
that the population inside the 55 dB DNL noise contour is 19,000 lower since 1993, an 8 percent
reduction. Both of these estimates carry with them an unknown but potentially large degree of
uncertainty due to the undocumented differences between the modeled and measured DNL levels the Port
used in its DNL contour calibration process in the Integrated Noise Model. As we previously explained,
we are concerned about the effects of propagating errors in translating noise measurements to noise
models to population benefits. Given the size (-0.9 dB) ofthe 1.9931995 change in DNL and the
uncertainty of any appreciable change in noise impacts at that level,. it is not clear that the Port's
estimated changes in the 65 and 55 dB DNL contours reflect anything more than a marginal shift in levels
for houses on the border ofthe respective contours. If, as the other measures we have examined suggest,
the DNL contours have moved only marginally (or not at all) since 1993, the changes are not meaningful,
and the estimates of 8,000 and 19,000 people benefited are laden with uncertainty.
The Port also calculates the change in population exposed to indoor noise levels in excess of 45 dB DNL,
reporting data for both open- and closed-window conditions, and closed-window data for both insulated
and uninsulaied houses. We find that the population noise exposure change resulting from the insulation
program is real and undebatable in the closed-window case: These people experienced an average of
about 7.9 dB reduction in interior DNL {(uninsulated, 1993, compared to insulated, 1995). There is no
question about the significance of a change ofthai magnitude (although the benefits accrue only to the
residents of insulated houses and then only when they are indoors with the windows closed).
With respect to the Port's overall indoor-population- exposure estimates, however, we have the same
concerns as we did with the results for the 55 and 65 dB DNL contour analyses: the propagation of error
in the population projections due to uncertainties in the underlying data and in the estimation procsss,
coupled with a very small change in mean DNL, as discussed below. Since the Port provided no
information that would permit us to judge the accuracy ofits population estimates, we cannot give full
weight to the Port's reported results.
Summary: DNL Reductions
The DNL metrics provide a very useful -- and widely accepted -- way to characterize overall changes in
airport noise. As a summary measure based on the average noise levels ofhundreds ofthousands offlight
operations over time, the annual DNL values incorporate, but mask, the particular variations in sound
exposure and noise impacts that are illuminated by the various other
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measures discussed above. Total and aircraft DNL metrics are the principal tools used to summarize the
overall changes in environmental sound levels associated with airport operations; total DNL reflects the
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tracks the changes in noise
changes in noise around the Airport from all noise sources, while aircraft DNL
attributed to aircraft operations.
since
We find that the reported reductions of 0.9 dB and 0.6 dB in aircraft and total DNL, respectively,
that there is
1993 - sven ifthey were accepted as statistically reliable ~ are too small to justify any finding
the
likely to have been a meaningful or appreciable reduction in speech interference, sleep disruption,
number ofpeople or percentage ofthe population "highly annoyed’ by aircraft noise, land use effects, or
from DNL
other noise impacts. The principal analytical tool used to calculate such population effects
conclusions about population benefits on the basis of
exposure levels ~- the FICON Curve -- permits no
base period for
such a small shift in measured DNL levels. If one accepts 1993 as the legally-mandated
comparison, the 0.9 dB reduction in aircraft DNL is clearly too small to produce even a reliably
measurable -- let alone "meaningful' reduction in on-the-ground noise impacts.
conclusion
Likewise, we find that the use of 1992, rather than 1993, as the base year would not alter our
Resolution
that the Port has not shown a significant or meaningful reduction in noise impacts since the
dB in aircraft DNL, -1.8 dB in total
was enacted. Given the small size ofthe change being measured (-2.3
reduction as
DNL), uncertainty remains a concern. Moreover, we are unconvinced that a sound level
small as 2.3 dB in DNL, over a four-year period, can reasonably be expected to produce an appreciable
reduction in the on-the-ground noise impacts experienced by the population surrounding a busy airport
with rapidly growing operations.
in aircraft DNL as
Over the past ten years as a whole (1986-1995), there has been a change of only -2.8
the "base year"
measured by the Port's RMS sites. For the reasons addressed above in our discussion of
of actual DNL
issue, we believe the ten-year change in aircraft DNL provides the most unbiased measure
for any base,
reductions at the Airport. The maximum change in aircraft DNL that the Port can show,
the single worst year
'vear’ within that ten-year time frame, is the -3.4 dB change in aircraft DNL from
(1989/1990) to date.
for measuring
The scientific literature does not establish any specific figure as a definitive DNL threshold
in aircraft
meaningful airport noise reductions. There is debate about how important a 3.0 dB change
of
DNL really is. While a -3.0 dB change in DNL will shift noise contours, and thus, by some measures
that is not much more
effectiveness, give an appearance of importance, it reflects a change in sound levels
noise
than barely perceptible -- and certainly not "appreciable." In terms of generating real, on-the-ground
-3.0 dB change in DNL would
impact reductions that people in their yards or houses would appreciate, a
for highway or rail noise
not generally be considered "significant;" it would not be considered a goal
abatement programs, for example.
DNL the cumulative
Consequently, ifwe were to use the more representative -2.3 dB change in aircraft
would conclude that the Port
improvement the Port has actually achieved over the past ten years -- we
the requirements ofResolution
has not demonstrated a sufficient reduction in real noise impacts to meet
A-93-03.
the majority ofthe
Based on our experience, the scientific literature and our best professional judgment,
over
Panel aiso finds that the maximum reduction the Port has shown (-3.4 dB in aircraft DNL, averaged
the 17 monitoring sites) - although it is certainly a laudable achievement for
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any airport with more than 300,000 operations a year -- is below the threshold of ‘meaningfulness' in
terms ofproducing a real, appreciable, "on-the-ground" reduction in airport noise impacts for
an affected
population -- especially when that DNL change occurs in conjunction with an increase in operations that
now produces a rising trend in Time Above 65 dB. In short, even over the six-year period the Port has
urged the Panel to consider, the majority ofthe Panel is not convinced that the Port's noise abatement
efforts have produced a sufficient reduction in real, on-the-ground noise impacts to satisfy the noise
condition ofResolution A-93-03.
This finding will no doubt be controversial. ‘The literature does not precisely define what constitutes
a
meaningful reduction in DNL, largely because there are so many acoustical and non-acoustical variables
that can affect people's responses. (An increase in aircraft operations is one such variable that has been of
concern to us here.) Addressing aircraft noise abatement, A. Harris commented indirectly
on the
meaningfiliness of different amounts ofnoise reduction when he noted, ‘How effective a noise abatement
tool is a displaced [landing] threshold? Not very -- a 4,000 foot displacement is required to obtain
a
reduction of 5 dB.... Even the 3,019 foot displaced runway... produces only a 3.2 dB reduction in landing
noise..." (A- S. Harris, "Relative Effectiveness of Options for Reduction of Aircraft Noise Exposure
around airports," INTER- NOISE '80 Proceedings, p. 814, emphasis added). Both the FAA and the Wyle
insulation program report for Sea-Tac note that at least 2 5 dB reduction in interior noise is needed, to be
noticeable, Should a 5 dB decrease in outdoor noise be viewed any differently? In highway traffic noise
analyses, most State Departments ofTransportation consider a 10-15 dB increase in "worst hour
equivalent sound level" a substantial increase, with a 5 dB increase being noticeable (trends in DNL-
track trends in’ worst hour equivalent sound level" to a large degree); when they consider high-way traffic
noise abatement, they aim for a "substantial reduction” that is at least 5 dB and typically 7 to 10 dB.
FICON illustrates the debate on the subject, quoting a conversation with W. Galloway at one point ("... in
a community noise environment, the majority ofa group ofpersons exposed to a 3 dB change in DNL
as
a result of a change in aircraft noise exposure would characterize the change as ‘clearly noticeable™
[p.3-15]) -- but FICON then goes on to say: ‘Although a 3 dB change may not represent a significant
impact on human health or welfare, particularly below DNL 55 dB, a change ofthis magnitude is
considered as an indicator ofthe need for additional analysis" (p.3-16). The FAA has established no
criterion for airport noise decreases or analysisofthe community effects of small reductions in aircraft
noise.
The recently issued Federal Transit Administration manual, Transit Noise and Vibration Assessment
(FTA, April 1995), cites the conclusion "by EPA and others" that a 5 dB increase in DNL is the minimum
required for a "change in community response.’ It also notes that a two percentage-point increase in
people highly annoyed’ (e.g., from 10 percent to 12 percent) is the minimum measurable change in
community reaction, and that the goal of abatement efforts should be to "gain substantial reduction... not
simply to reduce the predicted levels to just below the severe impact threshold" (p. 6-34). Typical rail
transit noise mitigation strategies seek reductions ofDNL 5 dB or greater.
Some members ofthe acoustical community suggest that there may be a real difference in the appropriate
standard to be used to evaluate the significance of noise decreases, as opposed to noise increases. It is
possible that there is a quality of downward insensitivity" associated with small reductions in already-high
noise levels -- that is, people may be more sensitive to increases than to decreases, and once sound
exposure levels are high enough to create annoyance and interfere with
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and
routine activities, it may take more than a marginal decrease in noise to "un-stick" that perception
produce an appreciable reduction in noise impacts.
As noted above in our SEL and TA analysis, the evidence at Sea-Tac also suggests that the additional
be
DNL improvements which the Port anticipates from its current noise abatement programs are likely to
over-taken by the effects on DNL ofthe continuing increase in operations. For that reason, we are not
confident that the abatement programs the Port has "scheduled and pursued” to date will generate even
small reductions in future DNL - or produce noticeable reductions in future on-the-ground noise impacts.
V. EFFECTIVENESS OF NOISE MITIGATION PROGRAMS
However, noise abatement is not the only tool in the Port's tool kit. Noise mitigation measures canalso
noise impacts. We turn now to our
generate important and meaningful benefits in terms of a reduction in
finding and conclusions about the significance ofthe benefits attributable to noisemitigation.
four
Under the Noise Mediation Agreement, the Port made Noise Remedy Program commitments in
major areas: residential acquisition and relocation; a transaction assistance/special purchase program,
residential noise insulation; and sensitive-use public building noise insulation.
1400
The Acquisition/Relocation Program has been completed as planned, with the buy-out of some
properties in the worst noise-impacted areas. The buy-out was essentially completed prior to enactment
with the purchase ofthe last few properties in 1995, the Port has declared the
_ of Resolution A-93-03;
acquisition program closed. A buy-out ofthis size is a major accomplishment for any airport, and
unquestionably constitutes a meaningful noise reduction benefit to the families who have been
successfully relocated. (However, the buy-out has also had some negative economic and social
repercussions for the adjacent neighborhoods. The comments in the 1993 AIRTRAC Final Report:
Mitigating the Environmental and Social Impacts of Air Transportation in Washington (p. 3-35)
residents..."
regarding "...'dead zones' ofboarded up houses and ill-maintained streets that frighten
ofthe buy-out.)
suggest the need for additional action to mitigate the effects
available to 3,000
With respect to the Transaction Assistance Program, we note that, while it is ostensibly
the Port for assistance
homeowners, only 254 - fewer than 10 percent ofthose eligible - have applied to
is not structured in a waythat
to date. The low utilization rate invites the suggestion that the program
that the Port has
homeowners find useful or equitable, or that such assistance is not widely needed, or
been less aggressive than it might be in making this assistance easily available.
Residential Insulation
The Port has done an impressive job of residential noise mitigation since 1993. The
A- 93-03, and it is now
Program was accelerated during 1993, shortly after adoption ofResolution
the Port had
proceeding rapidly (at a rate of about 110 homes per month). As ofDecember 1995,
noise reductions
insulated 3,647 homes including 2,888 completed since the end of 1992. The interior
interior DNL levels of
achieved - an average of 7 dB in the most seriously impacted homes, resulting in
and meaningful for the
45 dB or less in post-modification audits -- clearly appear to be both noticeable
evidenced by the
people affected, as one would expect from the magnitude of the reductions and as
The benefits are not in
positive reactions ofthe owners of insulated homes in the worst-impacted areas.
question; they are partial - indoor,
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closed-window relief only -- but they are directly measurable. We conclude that the indoor,
closed-window noise impact benefits are significant for most, and perhaps all, of the 8,570 people
residing in the homes insulated to date.
The Port has defined 10,000 homes (with approximately 23,500 residents) as eligible for noise insulation,
and has made a commitment to complete its full residential insulation program before beginning
construction of a third runway. However, the Port's Compliance Report shows 14,000 "housing units"
within the 65 dB DNL contour in 1995, and more than 17,000 within that contour in 1993. As noted
above, with a DNL change as small as - 0.9 dB, we are not convinced that the DNL contours have
changed more than marginally since 1993. Ifthe 65 dB DNL contour is not decreasing in size, expansion
ofthe residential insulation program may become necessary, since the Port expected a decrease in the
contour when it defined the present insulation eligibility criteria. We also note that Port Resolution 3125
places certain requirements on the Port staffwith regard to residential insulation prior to construction of
the proposed new runway and prior to its opening.
Turning to the longer periods of evaluation which the Port has advocated, we observe that, had the Port
accelerated its Residential Insulation Program just 18 months sooner - in January 1992, rather than in
mid-1993 - it couid have insulated an additional 2,000 homes by December 1995: 50 percent more than it
did, in fact, complete by the end of 1995. Had the Port accelerated the program three years sooner, in
mid-1990, an additional 4,000 homes could have been insulated by now. Doing so would have more than
doubled the number ofhomes insulated by December 1995, from 3,647 to approximately 7,600. The
number of people benefiting from that reduction in indoor sound levels would have also more than
doubled, from 8,570 to about 18,000. Instead of a Residential Insulation Program about one-third
completed, the Port would have presented this Panel with an important mitigation program that was
approximately 75 percent completed. We also note that the residents ofthose homes would have received
the benefits sooner and would be enjoying them today.
We give the Port a great deal of credit for "scheduling and pursuing” the residential insulation program
vigorously since 1993, but when the insulation is achieved does make a difference in how the benefits are
weighed. By the Port's own standard, the fact that it chose to apply substantial resources to this program
in mid-1993, rather than in 1990 or 1992, represents a missed opportunity to provide demonstrated,
meaningful, and continuing noise reduction benefits to several thousand people. Taken alone, this
increase would not satisfy the Resolution (substantial progress is needed on public buildings and multi-
family dwellings as well), but it will be an essential source of firture noise benefits.
The "Sensitive-Use' Public Buildings Insulation Program, another key component ofthe 1990 NMA
Noise Remedy Program, has been partially scheduled, is being pursued, and has had some achievements.
Here, the Port cites its progress on various pilot projects: two churches (2,080 people), the SeaToma
Convalescent Center (515 residents), the Soundridge Condominium project (134 peopie), and one private
school. The Port has also begun insulation work at Highline Community College. We note that the NMA
did not call for insulation of multi-family dwellings, and we commend the Port for this important addition.
The pilot programs are behind schedule, however. The two churches and the convalescent home are not
currently scheduled for completion until mid to late 1996. While the Compliance Report lists the
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completion date as April 1996, the 1993 Part 150 Update set mid-1995 as the
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expected time of completion. We also note that the Port has overstated the current benefits ofthe
community college project, by counting every person at the college (4,000 people) as receiving benefits
even though the Port has completed only 22 rooms in four out of 17 college buildings.
The 1990 Noise Mediation Agreement specifically envisioned an insulation program that would include
etc."
many types ofpublic buildings: "auditoriums, private schools, churches, day-care centers, libraries,
The Agreement also called for field and feasibility studies for public buildings bordering the 65 dB DNL
contour. The Port has not reported appreciable progress in these areas,
Tn addition to 23 schools, Table 1-7 ofthe Port's Compliance Report lists 15 hospitals or rest homes, 10
churches, and 2 libraries within the 65 dB DNL contour in 1993. The NMA did not call for the two-step
approach the Port is currently using to implement the Public Buildings Insulation Program (pilot projects,
followed at some point by a full program); that approach resulted from the 1993 Part 150 Update. While
we respect the Part 150 process, we are not sure that pilot studies were necessary, especially for private
schools. Different types of buildings do have their own peculiarities with respect to noise insulation work,
bur there would seem to be enough experience in the field of sound insulation for the Port to have
proceeded into a fuil program. It appears that the larger issue holding up progress on insulation of
sensitive-use public buildings and multi-family housing units may be the cost. As ofthe Panel's February
1996 hearing, Port staff said that they had developed a proposed budget, but funding was still "an issue."
Because insulation of public buildings and multi-family dwellings can reduce indoor DNL substantially, it
offers the promise of meaningful, long-term indoor noise reliefto a potentially very large number of
people in the vicinity of the Airport. The pilot projects are important, but, absent a timetable for the full
conclude that this component ofthe Port's
program and a funding commitment from the Port, we cannot
Noise Remedy Program is being effectively "scheduled and pursued" per Resolution A-93-03.
Finally, throughout this proceeding we have repeatedly expressed our concern about the delays in school
insulation. We find it difficult to conclude that there has been a "meaningful" reduction in on-the-ground
noise impacts as long as the majority of classrooms in the airport vicinity remain uninsulated and heavily
impacted by aircraft noise. The record provides ample evidence of speech interference in local schools,
and with the continuing increase in the number of daytime flight operations, classroom disruption can
only increase. We recognize that responsibility for the failure to move forward with school insulation
projects tests primarily with the Highline School District; the Port has made its commitment to funding
school
insulation projects clear. The factors cited by the School District - general rehabilitation costs, lack of
funds, and policy questions concerning noise insulation for older, inadequate school facilities - are
legitimate issues, but do not excuse years of inaction on this critical aspect of noisemitigation.
On balance, we strongly commend the Port for its efforts in the buy-out and residential insulation
have had a limited effect in reducing real
programs, but find that the Port's mitigation programs
on-the-ground noise impacts. For the population directly benefited, relocation and residential insulation
have provided real reductions in noise exposure (at least indoors, with the windows closed), but the
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number of people benefited remains relatively small, compared to the number ofpeople affected in the
Region. In our view, both the Noise Mediation Agreement and Resolution A-93-03 clearly contemplated
a broader reach ofnoise mitigation effects -- especially with
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regard to reducing noise impacts in schools and other sensitive- use buildings -- than the Port has
scheduled, pursued, and achieved to date.
V1. "MEANINGFUL AND REASCNABLE" REDUCTIONS IN NOISE IMPACTS
In our January 1995 Noise Order, the Panel stated, ""To meet its burden under the Resolution... the [Port]
must offer us reliable evidence, based on 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." We expressed our belief that the PSRC General Assembly, in
enacting the Resolution, "intended to condition approval ofthe third runway upon a showing that the
noise impacts ofthe existing Airport have been reduced in a significant way." And we set the parameters
of this proceeding by stating that neither an "unreasonable" (i.e., unreachable or infeasible) nor a
"meaningless" (i.e., inappreciable or trivial) reduction in noise was contemplated by the Resolution.
At the simplest level, we intended that particular wording to send a balanced, dual message, signaling the
Port that this Panel would not be persuaded by insignificant changes in noise levels or noise impacts, and
simultaneously signaling the community that we would not impose an unrealistic standard ofnoise
reduction (for example, requiring a 10 dB DNL reduction). Our choice ofwording echoed the language
used by varicus members ofthe PSRC Executive Board in the legislative debate surrounding Resolution
A-93-03, and reflected the extensive discussion at the Panel's August 1994 hearing. With our respected
colleague's dissent, however, that language has taken on added weight in this proceeding.
Meaningful Reductions in Noise
In view ofthe plain language ofResolution A-93-03, we cannot accept our colleague's interpretation of
the PSRC General Assembly's intent. That resolution, the governing document in this proceeding, sets a
specific test that must be met before the PSRC will approve the third runway: Based on "independent
evaluation" and on the 'measurement of real noise impacts," are ‘noise reduction performance objectives”
being scheduled pursued and achieved? In our view, it speaks to the purpose ofthe Port's noise programs
-- the objectives and the results. The Resolution does not ask whether the Port is performing its
ofthe publicimpact of
programs, but whether those programs are producing meaningful resultsin terms
airport noise. The fundamental goal of all of the Port's noise abatement andmitigation programs, from the
Stage 2 aircraft phase-out to the noise insulation at Highline Community College, is to reduce exposure
to airport noise in a meaningful way -- the "real noise impacts" stated in Resolution A-93-03. The PSRC
General Assembly and the executive Board did not require the services of a panel of outside experts
merely to read noise meters at the Airport, or to conduct an administrative audit to determine whether the
Port was implementing the noise programs it had promised the residents ofthe Region.
The Resolution explicitly requires the ‘measurement of real noise impacts" -- not measurement of
A-weighted sound levels, DNL, or SEL values, but measurement ofnoise impacts on real people and real
communities. In essence, the Resolution compels the Port to document the effectiveness of its programs:
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the real, on-the-ground results it is achieving as it works to reduce noise impacts.
[PAGE 29]
the Port to
We take the Resolution's wording at face value. The use ofthe term "measurement" required
scientific methods to
use a combination ofmeasured noise data and established
in turn,
document its noise reduction results in terms of "noise impacts." The phrase ‘real noise impacts,"
implies a standard based on meaningful results --a scientifically sound, persuasive showing that the
reach at
reductions in public exposure to airport noise (i) are actually occurring and (ii) are sufficient to
noticeable effects
least a threshold of significance, in terms ofproducing documented, appreciable, and
that the Port had
for the affected communities. And the requirement for "independent evaluation" meant
in fact accomplishing meaning
to demonstrate to an independent body - the Expert Panel -- that it was
and achieved."
results from the noise abatement and mitigation programs it has "scheduled, pursued
Executive Board
At the Panel's initial August 1994 hearing, PSRC Counsel stated that the PSRC
believe the
intended its "Implementation Steps" to be consistent with the Resolution. Accordingly, we
noise" not
Implementations Steps also call for results, i.e, "a reduction in measurable on-the-ground
form of a measurable,
merely in terms of a measurable change in aircraft SEL or airport DNL, but in the
PSRC explicitly
appreciable, meaningful change in the public impact ofairport noise. Counsel for the
reduction
confirmed this interpretation, when the Panel asked, in August 1994, "Is any measurable
examine the question of
enough to satisfy the requirements ofthe governing instruments? Or, are we to
within the meaning
whether the measured reduction in on-the-ground noise represents a real noise impact
ofthe Resolution?" PSRC Counsel replied "The latter.’
"should reflect the best
In the Panel's December 1995 Noise Order, we emphasized that our judgment
of changes in various noise
insights we can gain from established scientific sources about the significance
communities surrounding the
metrics as indicators of chances in the impact of noise on the people in the
record indicates.
Airport." That has been our approach throughout this proceeding, as the hearing
believe that Resolution
In light of the enormous importance of this issue for the Puget Sound Region, we
substantive question before us:
A-93-03 requires an impartial and scientifically accurate judgment on the
in public exposure to airport
the effectiveness of the Port's programs in producing a meaningful change
noise. That is the judgment we have presented in EMS Decision.
Reasonable Reductions in Noise
At a fundamental level,
In reaching our findings, we have also considered the issue of "reasonableness."
"unreasonable" in expecting the Port to demonstrate
we do not believe that the General Assembly was
in ‘real noise impacts’ for the
that its noise programs were actually producing a meaningful reduction
We believe
communities surrounding the existing Airport, before launching a major airport expansion.
noise -- real results in
that meaningful, appreciable improvements for the population exposed to Airport
achievable at Sea-Tac.
terms of on-the-ground noise impacts on real communities -- are
of "reasonableness" in this
More specifically, we examined two broad interpretations ofthe concept
We asked: Was this a reasonable effect
context: reasonableness of effort, and reasonableness of results.
We considered: Is the amount of
by an airport? Was the Airport reasonable in deciding to do what it did?
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noise reduction required by the Resolution reasonable? Would a reasonable observer say that this Airport
has done enough? Could the Airport reasonably have done more? We address each ofthese aspects in the
discussion below.
[PAGE 30]
Was this a reasonable effort by an airport? As the ACC argued in its October 1995 submittal: "[I]t is
results, not good- faith efforts, which the General Assembly Resolution requires." In our view, the issue is
not whether the Port has made an effort, even a great effort; the issue is whether there has been a
meaningful reduction of impacts.
Although many ofthe citizens we heard from over the course ofthis proceeding give the Port little credit
for what it has done, we fully recognize that the Port has made a serious effort in many areas, and we
strongly applaud the Port for doing so. The Noise Mediation Agreement, while important to the Region,
was not revolutionary in terms of the strategies it contained: nighttime operational restrictions had been in
place at Washington National, Minneapolis, and San Francisco; residential acquisition and residential and
public building insulation were being done by many airports. Flight track changes (and preferential
took the initiative in
runway use) had produced major benefits at Los Angeles and Boston. But the Port
the late 1980s to develop substantial noise abatement and mitigation programs at Sea-Tac and has
continued them through the 1990s. Although the Noise
Mediation Agreement process did not satisfy everyone, and ended rather abruptly just before the FAA
implemented the Four Post Plan, it did establish major programs -- particularly the Noise Budget and the
Nighttime Limitations Program -- that would be difficult or impossible to institute today, after passage of
the Federal Aviation Noise and Capacity Act. In addition, the Port implemented nighttime run-up
restrictions at Sea-Tac which helped to curtail that problem, and the power-back ban has answered
citizens' demands, even if, as the Port admits, the later did not appreciably reduce overall aircraft noise
levels. We also commend the Port for completing an extensive Part 150 Update in 1993 and for
scheduling a major effort on the next Part 150 Update in the summer of 1996. On the noisemitigation
side, the Port's residential insulation program is very large, and its current rate of residential insulation
work is exceptional.
We have nevertheless concluded, on the basis of all the evidence before us, that the ultimate results of
these efforts, in terms of real on-the-ground noise impacts for the communities affected by Airport noise,
have not been sufficient to satisfy Resolution A-93-03. Many people at the Port, including its noise
consultants, have labored long and hard to develop and implement abatement and mitigation programs;
substantial resources have been dedicated to the effort; yet many people in the Region remain severely
impacted by airport noise.
Was the Airport reasonable in deciding to do what it did? The Port is viewed by many people, including
noise control. The steps it has taken to date
every member ofthis Panel, as a leader in the field of airport
and few have
are perhaps more than "reasonable" in the sense that many other airports are doing less,
undertaken the type of coordinated effort the Port did in the Noise Mediation Agreement. However, the
bottom line under the Resolution is results.
Is the amount ofnoise reduction implied by Resolution A-93- 03 reasonable? Our colleague suggests that
the, noise reduction required by Resolution A-93-03, as we have interpreted it, is so large that it would
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be impossible to achieve. We disagree. For Sea-Tac, given the nature ofthe noise-sensitive development
around the airport, a 10 dB in outdoor DNL, for example, would probably be an unreasonable reduction.
This is not to argue whether 10 dB would be a desired goal, because in many instances, it is. Many
highway agencies use 10 dB as a goal for their traffic noise abatement projects. Dr. Suter, serving as an
make a difference.
expert for the RCAA, Stated that 12 dB would be desirable, if one really wanted to
A.S. Harris reported a 13 dB reduction in aircraft DNL in South Boston after the implementation ofthe
departure rerouting plan at Logan Airport, with a 76 percent reduction in people over a DNL of 65 dB
(Harris, INTER-NOISE '80
[PAGE 31]
Proceedings, P. 815). For Sea-Tac and for many airports, however, a goal of 10 dB DNL would probably
be unachievable or infeasible without major structural changes in operations, flight tracks, or land uses,
and hence would be interpreted in this sense as unreasonable.
But would, for example, a 5 dB DNL reduction be reasonable? Without endorsing 5 dB DNL as a
benchmark, per se, our answer is: yes, it might very well be achievable, and thus "reasonable."
Accomplishing a 5 dB reduction in DNL might be possible only with great difficulty, given the growth of
operations, the nature of the Four Post Plan, and the Port's current programs. But that does not mean that
the Port could not or cannot achieve real impact reduction through a variety of measures.
For examples insulation can be highly effective. A 10 dB reduction in indoor DNL appears both
reasonable and achievable around Sea-Tac Airport. Ofthe houses the Port has insulated, 70 percent
received an average reduction of about 8 dB since 1993 (7 dB inside and 0.9 dB outside) and 10 dB over
the longer period from 1989/1990 (7 dB inside and 3.4 dB Outside). Was chat a reasonable noise
able to
reduction goal? Yes; and the magnitude ofthe change was precisely the-reason why the Port was
show, for residents ofthose homes, a reduction on the order of 90 percent in time lost to speech
interference as well as great reductions in the potential for sleep disruption. Were those meaningful
insulated and
reductions in noise impacts? Yes. Were they enough, in the context of the number ofhomes
indoors with
the entire population adversely affected by airport noise both indoors and outdoors (and
the majority of the Panel that the Port had met the test of
open windows), to tip the balance and persuade
Resolution A-93-03? They were not.
Would a reasonable observer say that this Airport has done
has been
enough? The Port argues that "[a) reasonable observer would conclude that the Resolution
established
satisfied because thousands of people have received noise reduction benefits as measured by
But who is
scientific methods.” We have addressed benefits and methodology elsewhere in this Decision.
a day waiting for planes to pass by? A
a reasonable observer? A schoolteacher who loses 40 minutes
under the flight
business executive whose livelihood depends on airport growth? The mayor of a town
There is no
path? A General Assembly member who believes the runway should be vigorously pursued?
ofthis Panel, as
definable, completely unbiased "reasonable observer" in this situation. Even the members
ofnoise impacts,
observers charged with making an independent, objective evaluation ofthe reductions
have come to differing conclusions.
have found) the
Could the Airport reasonably have done more? Mr. Lewis suggests that, even if (as we
the Resolution,
Port failed to demonstrate the meaningful reduction in "real noise impacts" required by
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we should nevertheless find in favor of the Fort on grounds that there was no evidence that the Port
could have taken other measures that would have been expected to make a significant difference in
overall noise impacts.
That is not the view we take. The Noise Mediation Agreement established a basic set of commitments; it
did not preclude the Port from taking additional action. Airport noise has been an extremely contentious
issue in this Region for more than 25 years, dating back at least to the construction ofthe second runway.
As we observed earlier, the Port has long known that many people were dissatisfied with the Noise
Mediation Agreement process, the FAA's introduction ofthe Four-Post Plan, the prospect of a third
runway, and other Airport actions. Controversy, distrust, and pressure for additional action are not new.
As the consultants representing the Fort in this proceeding stated in their 1993 AIRTRAC Final Report
(p. 3-35): "There is sometimes a difference
[PAGE 32]
of opinion about what constitutes a commitment. For example, Sea- Tac did not complete planned land
acquisition and home and school insulation programs for areas impacted by the second runway built in
1970, and this has led to a perception by some in the community ofbroken promises. Apparently, the
airport did not consider itselfbound by this plan." In 1993, by contrast, the Port took the initiative not
only to meet its obligations for residential insulation but to proceed with the insulation work at a rate far
faster than the pace stipulated in the 1990 Noise Mediation Agreement. That was a wise decision, in our
view, and one that clearly reflects the Port's understanding that, at least in this respect, the Noise
Mediation Agreement is not a limiting document: there was more the Port could and should do.
We are uncomfortable with the notion of a ruling that would turn on a speculative interpretation ofwhat
more the Port could (or could not) have done, rather than on the merits ofthe case. The Port did what it
did - an exceptional effort in many ways, but one that fen short of generating meaningful, real reductions
in on-the-ground noise impacts for the people of the communities subjected to aircraft noise. Our task is
to render an informed and objective judgment on the efficacy of the Port's programs in reducing actual
noise impacts, not to speculate on what else the Port might have, or could have, or should have done.
Because ofthe way the logic ofthis case has developed, however, we are now compelled to address that
speculative question. Mr. Lewis believes that any additional efforts the Port might have made would not
have amounted to enough to make any difference in meeting the test ofResolution A-93-03 as we
interpret it. We believe that the Port could have done more, and that, had it done so, the additional
improvement probably would have made a material difference in real, on-the-ground noise impacts,
turned a marginal improvement into a meaningful one, and therefore affected the final outcome ofthis
proceeding.
The issue of "what else” the Port could have done was addressed at some length in the course ofthe
Panel's bearings. Our colleague suggests that the community groups have not met "their threshold
burden" of showing how the Port could have taken additional action to produce "significantly more
meaningful reductions in noise impacts." We believe that primary responsibility for proposing and
developing significant noise abatement and mitigation programs rests with the Port, not with the
community advocates. In this context, we note, however, that the ACC has suggested a number of
additional actions including the concept of a tradeofflinking a Federal Part 161 program that
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with
proposes some new noise abatement restrictions on aircraft operations (some capacity limits)
approval of a third runway (capacity enhancement), as a combination package to produce both improved
noise relief and a net capacity gain.
The Port contends -- and the entire Panel agrees -- that the measures it has taken to date are the ones that
were most likely to produce significant benefits, because they addressed airport noise at the source.
Those measures were easier to implement than some other strategies -- for example, flight track changes,
which can also be highly effective in producing significant noise- impact reduction. Moreover, programs
that produce smaller benefits to a large group ofpeople or significant benefits to a smaller group of
people can have a cumulative impact. Based on the discussions during the hearings, as well as the analysis
in the Noise Mediation Committee Technical Report, it is clear that more could have been done before
1990, since 1990, and since 1993.
We list below several abatement and mitigation strategies that we believe had the potential to be
meaningful, feasible and reasonable. We are not suggesting that the Port had to pursue every
[PAGE 33]
conceivable strategy; we merely note that some additional -- and potentially very effective -- actions were
possible.
With respect to noise abatement, for example, the Noise Mediation Agreement could have set a faster
Stage 2 phase-out schedule in its alternative process to the complex Noise Budget calculation; ifthe
transition to Stage 3 had been completed in 1995, there would have been, by both the Port's and our
estimates, an additional 1.5 dB reduction in DNL (such a faster phase-out, if part ofthe NMA, would
have pre-dated the Aviation Noise and Capacity Act and the Part 161 process). Implementation of
minimum population exposure flight tracks could have had an important effect; the Port noted in the
February 1996 hearing that its consultant had developed "useful" flight track changes for Four Post Plan
noise abatement back in 1990 (as described in the 1991 Noise Mediation Committee Technical Report),
and Resolution A-93-03 has called for efforts to reduce the noise impacts ofthe Four-Post Plan since
April 1993. The Port might also have considered adopting a preferential runway plan during "low
periods" of activity to reduce population exposure to Airport noise.
have
In addition, the Noise Mediation Agreement contemplated the following abatement activities which
not yet been achieved (which is, in part, why we found the Port to be in substantial but incomplete
compliance with the NMA: enforcement ofthe North Flow Elliott Bay/Puget Sound nighttime noise
abatement departure procedures (which could have been scheduled, pursued, and achieved at any time
after these procedures were first implemented); use ofthe North Flow Elliott Bay/Puget Sound departure
of
procedures or South Flow Arrival Corridor procedures whenever feasible (e.g., during daytime periods
the
lower activity); and, finally, implementation of controls on engine thrust reversals, to reduce noise in
immediate vicinity of the airport.
On the mitigation side, the single-family residential insulation program could have been accelerated
earlier, as we have previously discussed and the public buildings and multi- family residential insulation
In light ofthe Part's lack of progress on
programs could have been pursued much more vigorously.
insulation projects after construction ofthe second runway, we believe it would have been in the Port's
best interest to move as decisively as possible in carrying out its commitments under the 1990 Noise
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Mediation Agreement.
These lists are by no means comprehensive, but they do persuade the majority ofthe Panel that the Port
could have taken at least some additional steps to increase the total amount of benefit (in terms of
demonstrated, real reductions of noise impacts) in a manner that cumulatively could have shown us
enough objective evidence of on-the-ground results to meet the intent of the Resolution. These strategies
would have, in different ways, reduced DNL, reduced mean SEL reduced the Time Above the various
levels, decreased speech interference, reduced sleep disturbance, reduced annoyance, and reduced
incompatible land uses in the various DNL contour zones.
Accordingly, we conclude that a straightforward interpretation ofResolution A-93-03 does not impose
an unrealistic standard ofnoise reduction on the Port, as Mr. Lewis contends. We do not believe that the
amount ofnoise abatement and mitigation necessary to produce an objectively meaningful or significant
reduction in "real noise impacts" within the meaning ofResolution A-93-03 was infeasible, unreachable,
or unreasonable.
[PAGE 34]
VII. CONCLUSIONS ON THE EFFECTIVENESS CF THE NOISE ABATEMENT AND
MITIGATION PROGRAMS This Decision represents our best professional judgment, based on many
years of experience, many days ofpublic hearings, many months ofreview and analysis ofthousands of
pages of data, evidence, and argument, and countless hours of deliberation and debate among the
members ofthe Panel. It was not an easy decision, and it is not a political decision. It is the independent
evaluation required by Resolution A-93-03.
How much abatement of aircraft noise is necessary to generate "enough" reduction in on-the ground
noise impacts to satisfy Resolution A-93-03? The ACC, relying on the expert testimony of Dr. Fidell,
suggested that a DNL reduction on the order of 4.5 dB -- presumably in conjunction with vigorous action
on the mitigation front -- is the minimum needed to produce a meaningful change in noise impacts for the
affected population and to support reliable findings of significant benefits in terms of reductions in speech
interference, awakenings, and other noise disruption. "To be meaningful," the ACC said in its October
1995 submittal, "a reduction (measured in Ldn), must be at least 4.5 dB." Without necessarily endorsing
4.5 dB DNL as a benchmark for determining a meaningful reduction in airport noise, a majority of the
Panel has found after reviewing a very large array of specific evidence at Sea-Tac Airport, that at this
Airport, under these particular circumstances, a 3.4 dB DNL reduction over a six- year period has not
been sufficient to produce a demonstrated and "meaningful" reduction in real, on-the-ground noise
impacts.
We have also carefully reviewed the extensive documentation the Port and other parties provided on the
size, nature, and effectiveness of the Port's noise mitigation projects under the Noise Remedy Program.
We have found that the Port's mitigation work is effective in producing real indoor (closed-window)
noise relief for the residents of insulated homes, but that the scope ofthe Port's scheduled insulation
program remains incomplete with respect to schools, other sensitive-use public buildings, and
multi-family dwellings. The Port's mitigation efforts, while substantial, have not yet reached, or been
"scheduled" to reach in any concrete sense (i.e., with an explicit timetable and commitment of resources),
a large enough portion ofthe affected population to allow us to conclude that, in combination with the
abatement results, the resulting overall reduction in noise impacts has been "enough" to meet the test
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imposed by Resolution A-93-03.
Accordingly, a majority ofthe Panel finds:
1. That despite the Port's impressive, good-faith efforts to implement effective noise abatement and
mitigation programs, the demonstrated results ofthe programs it has scheduled, pursued, and achieved
since Resolution A-93-03 was adopted (1993-1995 and, alternatively, 1992-1995) do not constitute a
"meaningful" reduction of real, on-the-ground noise impacts sufficient to satisfy the noise condition of
Resolution A-93-03;
2. That the demonstrated results of the noise abatement and mitigation programs the Port has "scheduled,
pursued, and achieved’ since 1989/1990 do not provide evidence strong enough to establish, with any
degree of confidence, that there has been a "meaningful" reduction of real, on-the-ground noise impacts
sufficient to satisfy the noise condition ofResolution A-93-03; and
[PAGE 35]
3. That the Port is not likely to achieve significantly more reduction in real, on-the-ground noise impacts
in the near future with the abatement and mitigation measures it has scheduled to date and is currently
pursuing.
We reach these conclusions for a number of reasons, including:
(i) the absolute size ofthe changes in measured DNL (we cannot conclude that the Port has met its
affirmative burden under the Resolution on grounds as weak as a maximum DNL change below the
threshold of significance),
(ii) our analysis of the meaning of the small average decrease in Time Above 85 dB at the Port's
monitoring sites (2-3 minutes per day), the increase in Time Above 85 dB at RMS 11 since 1993, and the
current trends in Time Above 65 d]3 and 75 dB, in terms of real on-the-ground noise, impacts;
(iii) our analysis of the corresponding size and direction ofthe changes in average SEL, nighttime Leg,
DNL contours, number and percentage ofpeople "highly annoyed," and other measures discussed above;
(iv) the importance of the factors that are offsetting the improvements the Port has realized to date, such
as the increase in the total number of nighttime operations and the unacceptably low rate of compliance
with the nighttime noise abatement
corridors;
(v) the limited degree of confidence we place in the reliability ofthe Port's analysis of noise abatement
benefits in the absence ofneeded information on confidence interval documentation ofINM assumptions
and adjustments, and sensitivity analyses, as well as the estimation difficulties inherent in using the
available analytic tools to extrapolate significant benefits from very small changes in DNL; and
(vi) the incomplete range of noise mitigation programs the Port has "scheduled, pursued, and achieved"
to date, particularly with respect to the sensitive-use public buildings included in the 1990 Noise
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Mediation Agreement.
On the preponderance ofthe evidence, we cannot conclude that there has been, as ofDecember 1995, a
meaningful or appreciable reduction in the real, on-the-ground noise impacts experienced by a large
portion ofthe population affected by Sea-Tac airport noise, since 1993, since 1992, or since 1989/1990.
There is little doubt that, absent important new initiatives, the Port's current noise abatement efforts will
have little additional effect. The steady growth in aircraft operations expected by the Port - which
provides the essential justification for constructing the new runway - is already slowing the smail DNL
improvements the Port has achieved in recent years, and is likely to undermine any additional noise
reduction the Port may achieve in the future. In this context, the Port's noise mitigation efforts will
become increasingly important; insulation is one area where the Port can readily take additional action.
But even a substantially expanded mitigation program can ultimately provide only partial. indoor relief.
[PAGE 36]
Although the Port's ability to substantiate the validity ofits estimates of real, on-the-ground noise impacts
was weakened by its failure to supply documentation on the statistical reliability of (i) its data and (ii) its
modeling and estimation processes, the Port has nevertheless provided an enormous amount ofuseful
information and analysis. The Port has complied with the Panel's request to provide time-series data on
many different aspects of aircraft noise at Sea-Tac, from the basic DNL trends to the distribution of SEL
peaks, the minutes per day above 65, 75, and 85 dB, and many other measures. This multifaceted
.approach to the evaluation of airport noise -- a combination ofmany different ways oflooking at aircraft
noise levels and the associated noise impacts on the community -- has been valuable for a number of
reasons. It provides a better picture ofwhat is actually happening with Sea-Tac Airport noise levels than
DNL alone can convey, it permits the Panel, the PSRC General Assembly, the Port, and the community
to assess the actual noise exposure changes and on-the-ground noise impacts more fully; it supplies
much-needed detail on critical aspects ofthose noise impacts (such as the actual amount oftime that
classrooms are subject to noise levels above the threshold for speech interference); and last but not least,
ifthe results show an internally consistent pattern across a variety of different types of measures (as they,
in fact, do in this case), it provides all parties with a considerable degree of added confidence in the
robustness of conclusions about the reductions in noise impacts - - the on-the-ground changes in public
exposure to Airport noise - - which the Port's current noise abatement and mitigation programs have
produced and are likely to produce.
RECOMMENDATIONS (BY THE MAJORITY)
In the course ofthis proceeding, the Pane! has had the benefit ofthe creative, analytical thinking of many
different parties regarding additional noise abatement and mitigation measures that may, alone or taken
together, reduce the future noise impacts associated with Sea-Tac airport. The Port has invited the Panel
to offer our recommendations as to what the next steps should be regarding noise abatement and
mitigation. The majority of the Panel accepts that invitation.
On the one hand, we do not think that many easy actions remain; the major programs on Stage 2
phase-out and nighttime Stage 2 restrictions are already in place. On the other hand, there are some
additional actions that can be implemented relatively quickly and, in some cases, at relatively low cost.
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As Mr. Lewis has noted, noise abatement and noise mitigation are not simple. Externalities abound that
make an airport proprietor's job difficult. The Port generally gets all the blame (and the credit) for
changes in the aircraft noise environment in the Region. The reality is that actions by the FAA, the
airlines, local organizations, and State and local political entities all affect the situation. However, while
many actions are not within the Port's legal authority, they are nor
necessarily beyond its range of influence. (Indeed, the Port has been portrayed by many ofthe people
from whom we have heard, and by a number ofthe submittals that we have read, as a major force in the
Region.) That influence should be brought to bear, wherever possible, to reduce on-the-ground noise
impacts.
[PAGE 37]
In the spirit ofResolution A-93-03, we offer the following specific recommendations:
1. That the PSRC and the "Coordinating Committee" established by MOU pursuant to Resolution
A-93-03 (the PSRC, the Port, WSDOT, and the FAA) promptly take steps to mediate and resolve the
impasse between the Highline School District and the Port on the issue of noise insulation for schools, to
enable the Port to move forward rapidly on its commitment to insulate the schools and significantly
reduce classroom speech interference.
2. That the Port implement its stated plan to upgrade its noise monitoring system, with no fewer than 25
.permanent monitoring stations located throughout the affected communities; and that the results be
publicly disseminated, at regular intervals, in the form of aircraft DNL, SEL, and Time Above metrics.
3. That the Port and the organizations representing the affected communities jointly sponsor social
surveys at regular intervals to assess the effectiveness of future noise abatement and mitigation measures
in terms ofperceived noise impacts. We concur with the view expressed by the Port's noise consultants in
the 1993 AIRTRAC Final Report (p. 3-33): "The way to avoid incorrect predictions of community
response to a ... [noise reduction] action is to ask the community directly how it feels about a particular
airport action and the proposed mitigation program connected to it."
4. 'That the Port address the impact of ground-related aircraft noise by (i) implementing the
thrust-reversal noise impact reduction activities called for in the Noise Mediation Agreement; and (ii)
working to minimize the number, level, and duration of daytime engine run-ups, which are likely to
increase as operations grow. (We note that the increases in TA 65, 75, and 85 dB at RMS site 11 in
recent years may be a consequence ofground- related noise.)
5. That the Port take the following actions to improve the on- the-around reduction of nighttime noise
impacts:
a. Negotiate and obtain a public commitment from the FAA for full cooperation in rigorously and
aggressively enforcing compliance with the current North Flow Nighttime Departure Noise Abatement
Procedures. The Port, at a minimum, should notify airlines of violations ofthese nighttime noise
abatement procedures. Better, the Port should institute procedures to apply pressure, through
enforcement penalties and/or the power of public opinion in the media, to reduce violations (for example,
publishing fines and performance scorecards in the Region's newspapers).
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b. Work closely and aggressively with KCIA and Alaska Airlines to eliminate the carrier's two nighttime
Stage 2 cargo flight arrivals and departures, which weaken the effectiveness ofthe Port's nighttime Stage
avoid
2 ban; and develop, in conjunction with KCIA and local government officials, a strategy to
additional Stage 2 nighttime flights to and from KCIA in the future.
in the middle of the night (e.g., 1:30 a.m.
c. Work with the airlines to minimize the total number of flights
to 5:30 am.).
[PAGE 38]
d. Continue to minimize the number ofvariances issued for the Nighttime Limitations Program through
aggressive persuasion with the airlines, including the use ofthe media.
3 aircraft continue to be used for nighttime
e. Work with foreign air carriers to ensure that Stage
international flights.
from
f Work with owners/operators of Stage 2 aircraft under 75,000 pounds (which are currently exempt
the use of
the Nighttime Limitations Program) to secure their cooperation in minimizing or eliminating
such aircraft during the nighttime period. (There were, on average, 13 exempt Stage 2 nighttime flights
of 1995.)
per month in the second and third quarter
minimize nighttime engine run-ups; we note that, although many
g. Continue to work with the airlines to
have levels higher
ofthe events are exempt from the King County Code, the exempted nighttime events
than the code permits. Existence of an exemption does not mean elimination ofthe impacts on people.
and
6. That the PSRC, the FAA, and the communities affected by airport noise participate actively
in implementing
constructively in the Port's upcoming Part 150 review, to propose, evaluate, and assist
that will maximize the net benefits for the region and provide
any feasible noise reduction measures
but not be
meaningful noise mitigation for the impacted area. The Port's Part 150 process should include,
limited to, the following actions:
and enforce the North Flow Daytime Departure
a Evaluate the actions needed to apply, monitor
Mediation Agreement.
Duwamish/Elliott Bay Noise Abatement Procedures specified in the Noise
ofperiods of lighter activity
Investigate, and, if possible,. implement, use ofthis corridor during periods
during the day such as mid-morning and mid-afternoon.
the North Flow Nighttime
b. Evaluate the feasibility of extending the "nighttime" hours of use for
the evening " shoulder” (8 to 10
Departure Noise Abatement Procedures (currently 10 p.m. to 6 a.m.) to
p.m.), and, ifpossible, to the early morning "shoulder" (6 to 7 a.m.) as well.
use of "minimum population exposure" flight tracks,
c. Reevaluate, with FAA and community input, the
of arrival noise as Stage
in light ofthe increase in flight operations and the shift in the overall importance
track changes for Four Post
2 aircraft are phased out. The Port had studied, and identified "useful" flight
ofthe following options would be
Plan during the development ofthe Noise Mediation Agreement. Any
expected to reduce overall population exposure to aircraft noise: (i) over-water southern corridors for all
or
south departures where the east turn does not occur until the aircraft reach Commencement Bay
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beyond; (ii) north-flow arrival procedures that route aircraft over the water (with a turn in the
Four-Postarrival stream); or (iii) the use of a north-flow stream more often at night, coupled with tightly
enforced, high-compliance nighttime departure routes. There are some difficult trade-offs in this process,
but we do not accept the contention that all possible changes in flight tracks simply shift noise
among
communities, with no net reduction
[PAGE 39]
in number of people impacted. Flight track changes offer the Potential for abatement of aircraft noise
impacts once the Port has exhausted the benefits ofthe Stage 2 phase-out; we note again that Resolution
A-93-03 explicitly requested the FAA to consider modifications to the Four Post Plan to reduce noise
impacts.
d. Evaluate, with FAA and community input, the potential net benefits of a noise abatement departure
profile employing a steeper angle of climb, coupled with an expanded residential acquisition and
insulation program if; as a result of a steeper departure profile, the 75 dB DNL contour expands in the
immediate vicinity of the airport while areas farther out receive benefits.
e. Evaluate, with FAA and community input, the potential net benefits of preferential runway use during
"low activity" periods (would more use ofthe east runway, for example, result in reduced overall
population noise exposure?) -- coupled with an expanded residential insulation and acquisition program,
as needed.
7. That, with respect to the Noise Remedy Program, the Port take the following, actions:
a. Begin a rapid, full-scale program of school insulation as soon as the impasse with the Highline School
District is resolved, with the maximum feasible commitment ofre-sources and the earliest possible
completion schedule.
b. Compiete the "sensitive-use" public buildings insulation pilot studies and fund the full program
envisioned in the Noise Mediation Agreement, as well as a program for insulation of multi- family
dwellings, with an aggressive schedule to allow completion as soon as possible. The Port Commission is
on record as committed to these programs.
c. Evaluate the possibility of an expanded residential acquisition program offering more ofthe most
severely impacted people the buy-out option, even if no additional Federal money is made available for
this purpose. While relocation is riot desired by all (nor easy for anyone), the environs of a major airport
are plainly not the best location for residential neighborhoods.
d. Work with the PSRC and the affected communities to design and implement alternative,
noise-compatible uses ofthe land within the current acquisition zone. We note that the acquisition
program has some very strong critics because of its adverse effects on the quality ofneighborhoods for
the remaining houses and businesses.
e. Further accelerate, if possible, the rate of insulation for homes now included in the residential noise
insulation program, and consider expanding the area eligible for noise insulation ifthe Airport's 65 dB
DNL contour remains at or near the 1993 contour boundaries.
41 0f 50
f Investigate possible modifications to the insulation program to mitigate the impacts of low frequency
noise and vibration (a concern the public raised repeatedly during the Panel's hearings).
[PAGE 40]
8. That the PSRC and the Coordinating Committee take the lead in addressing the difficult, controversial
task ofreducing
present and future noise impacts, with the following actions:
Port are
a. Recognizing the degree to which parties and factors outside the direct authority of the
undercutting the effectiveness of the Port's current efforts to reduce noise impacts, initiate and coordinate
remedial action. Such coordination may include facilitating the use of mediation, marshalling [sic] State
and local public resources where needed, providing public information via the media, or otherwise
addressing the roadblocks that now prevent the residents ofthe Region from realizing the full benefits of
the Port's existing abatement and mitigation programs. The PSRC and the Coordinating Committee are
the principal entities in a position to take effective action to resolve the local problems caused by the
"balkanization" of responsibility among the Port, the FAA, KCIA, the Highline School District, and other
parties.
b. Create guidelines or other equitable procedures for dealing fairly with the conflicting views and needs
of different communities when a proposed noise reduction strategy results in a net improvement but
causes a transfer of noise impacts.
of incompatible land uses and to
c. Take effective action on land use issues to minimize the introduction
facilitate compatible redevelopment of currently incompatible land uses, including implementation ofthe
recommendations on land use issues in the 1993 AIRTRAC Final Report.
d. Investigate creative ways of linking noise reduction objectives with airport demand and system
needs.
management strategies, including intermodal solutions to local and regional transportation
DISSENT (BY MR. LEWIS)
that ‘noise
[ would find that the Port has met its obligation to show under PSRC Resolution A-93-03
reduction performance objectives’ have been "scheduled, pursued and achieved measurement
... based on
has failed to
ofreal noise impacts." As a result, I cannot join my colleagues in concluding that the Port
I am
satisfy the noise reduction condition ofthe Resolution and must dissent from their Decision.
the
convinced that my colleagues have imposed upon the Port a burden that was never contemplated by
General Assembly.
noise
The Port showed us that it has scheduled, pursued and achieved the objectives of the two major
and the
abatement programs contemplated by the Noise Mediation Agreement -- the Noise Budget
aircraft at
Nighttime Limitations Program -- by significantly reducing the use of the loudest, Stage 2
level of real noise measured
Sea-Tac, and virtually eliminating them at night. The resulting impact on the
on-the-ground has been captured by an extensive array of noise
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[PAGE 41]
measurements compiled by the Port that shows a consistent pattern and continuous reduction in DNL
since these Programs began, associated with the reduction in the loudest aircraft events (which, as the
majority concedes, does make a difference in on- the-ground noise impacts)- The Port also showed that
its residential noise mitigation program has insulated several thousand homes, producing noticeable and
meaningful reductions in measured interior noise levels. After carefully considering all ofthe evidence, it
is my judgment that these achievements, confirmed by the measurement of real on-the-ground noise,
should be sufficient to satisfy the noise reduction condition of the Resolution.
The majority ofthe Panel, unfortunately, does not agree. Their determination that the Port has not shown
a sufficiently meaningful reduction of noise impacts to satisfy the noise condition ofthe Resolution
ultimately depends, as I understand it, upon two essential points: (i) that as to its noise abatement
programs, the Port has not established through the use of "established scientific methods" that the
reductions in measured noise levels it has shown signal a "meaningful" reduction in noise impacts; and (ii)
that as to its noise mitigation programs, the Port has missed an "opportunity" to provide insulation
benefits to thousands of additional residents ofthe affected community.
I do not believe that the General Assembly required a reduction in measurable on-the-ground noise that
would cross an undefined technical threshold of "meaningfuiness" so high that doubts about the
significance ofthe resulting reductions in noise impact would be resolved to the satisfaction ofthe
scientific community. The majority places too much emphasis on measurements ofnoise impacts that
could not be made by the Port and were not expected by the General Assembly, and on the failures,
rather than the successes, ofthe Port's insulation program.
It seems unlikely to me that the PSRC would decide not to authorize the third runway simply because: (i)
the Fort cannot prove through the use of established scientific methods that a measured reduction in DNL
of 3.4 dB since the Noise Mediation Agreement was implemented, with continuing reductions since 1993
when the Resolution was enacted, reflects a "meaningful" reduction in noise impacts; (ii) the Port was
unable to eliminate the unavoidable uncertainty associated with the extrapolation of noise impacts from
incremental changes in measured noise and did not document the assumptions and adjustments it made
when using the Integrated Noise Model; (iii) the number of aircraft operations has increased, as the
General Assembly assumed it would when it determined that a new runway should "vigorously" be
pursued; (iv) significant reductions in the loudest noise events associated with the greatest interference
with speech and disturbance with sleep have, in recent years, been offset to some extent by increases at
lower sound levels that inevitably accompanied the recent, expected growth in the number of aircraft
operations; and (v) the Port's noise mitigation programs have not yet reached their full potential. Yet this
appears to me to be why the majority has ruled against the Port. In my judgment, based upon all the
evidence, there has been a sufficient reduction in real, on-the-ground noise impacts to satisfy the
requirements ofthe Resolution.
In recognition of increasing capacity problems at the Airport, the General Assembly declared in the
Resolution that "the region should pursue vigorously ... a third runway at Sea- Tac" and determined that,
under present circumstance the third runway shall be authorized by April 1, 1996 "[w]hen noise reduction
performance objectives are scheduled, pursued and achieved based on independent evaluation, and based
on measurement ofreal noise impacts."
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[PAGE 42]
The Resolution was adopted by the PSRC three years after the Port implemented the Noise Mediation
Agreement. The Agreement was, as the majority observes, an "important milestone" in the reduction of
adverse environmental impacts from airport operations. It scheduled three bold initiatives: the Noise
Budget, the Nighttime Limitations Program and the Noise Remedy Program. Unfortunately, the
precipitous conclusion ofthe noise mediation, the disturbing introduction of the Four Post Plan, and
lingering doubts about the motives ofthe Port left many in the community unconvinced that the Port
would meet its commitments, that these programs would make any difference, and that the Port's
sophisticated computer models had anything to do with the real "on-the-ground" noise they perceived.
The General Assembly therefore called for an "independent evaluation" ofwhether the Port had
scheduled pursued and achieved 'noise reduction performance objectives ... based on measurement of real
noise impacts.’ The enactment ofResolution A-93-03 manifested the General Assembly's apparent desire
for independent, objective answers to several basic questions:
Did these programs establish significant noise reduction objectives?
Has the Port done what it said it would do to reduce on-the- ground noise?
Do actual measurements of on-the-ground noise confirm that the noise reduction objectives ofthe Port's
programs arc being achieved?
1 believe the correct answer to all ofthese questions is "yes."
The Port's Noise Budget and Nighttime Limitations Program established ambitious noise and access
restrictions under the Noise Mediation Agreement that were, as the majority acknowledges, most likely
to produce significant benefits because they addressed airport noise at the source: the use of loud Stage 2
aircraft, especially at night. These restrictions were farmore stringent than the national rules established
by Congress when it later enacted the Airport Noise and Capacity Act of 1990, requiring a phase-out of
Stage 2 aircraft. In fact, if the Noise Mediation Agreement had not been negotiated before November
1990, and therefore exempted from the Act, the Port would have been unable to reduce or limit Stage 2
aircraft operations as it has under its noise abatement programs.
All of the members ofthe Panel have found that the Port is in substantial (if incomplete) compliance with
the Noise Mediation Agreement and that the scheduled noise reduction objectives ofthe Noise Budget
and Nighttime Limitations Program have been pursued and have achieved a reduction in measured "on-
the-ground" noise captured by DNL at the Port's permanent monitoring sites both since the Agreement
was made in 3990 and since the Resolution was enacted in 1993.
In our January 9, 1995 Noise Order, however, the Panel determined that the Resolution required the Port
to show more than just compliance with the Noise Mediation Agreement and a resulting measurable
reduction in noise levels; the Fort, we felt, had to show a "meaningful" or "significant' reduction in noise
impacts on the community. In retrospect, it seems to me that the Panel may have been mistaken. The
subsequent hearings, our protracted deliberations and the split on this Final Decision
all reflect the difficulty of determining how the "meaningfulness" of noise reductions should be assessed
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for the purposes ofthe Resolution.
[PAGE 43]
When we issued our Order in January 1995, the Panel reasoned that the General Assembly did not need
to obtain an "independent evaluation" by a panel of outside experts ifthe only question was whether any
reduction in noise impacts evidenced by actual on-the-ground sound measurements had been "scheduled,
pursued and achieved" by the Port, and so we held that the reduction in noise impacts had to be
"meaningful." At the same time, however, we explained that the Resolution did not impose upon the Port
a standard of performance that it could not possibly meet. The General Assembly, after all, had voted to
pursue construction ofthe third runway "vigorously" if the stared conditions were satisfied, and it would
have made little sense to impose an "unreachable" or 'infeasible" condition in those circumstances. I
thought that our consideration ofthe Noise Issues required the Panel to assess the significance of the
reductions in noise impacts scheduled, pursued and achieved by the Port given what it was reasonable to
expect (from the General Assembly's perspective) that the Port could do to reduce the impact of
airport-generated noise on the surrounding community by the time the third runway was to be authorized
by the PSRC.
The "meaningfulness" and "reasonableness" standards we imported to the Resolution do not provide a
definitive benchmark or prescribe the use of established scientific methods to assess the adequacy ofthe
reductions in noise impacts achieved by the Port. We acknowledged in our December 1995 Preliminary
Order on Phase II Noise Issues, in fact, that the Resolution called upon the Panel to use our "best
professional judgment as a whole, the pattern of change in noise impacts
... to determine whether, taken
is sufficient In my view, the Panel's assessment should
... to meet the requirements ofthe Resolution."
reflect both 'the best insights we can gain from established scientific sources about the significance of
changes in various noise metrics as indicators of changes in the impact of noise on the people in the
communities surrounding the Airport,’ and our knowledge and experience in dealing with the institutional,
operational, and regulatory constraints that limit an airport owner's ability to reduce the noise impacts of
a busy, growing jet airport. Based upon these considerations, I am confident that the pattern of change in
measured real on-the-ground noise levels shown by the Port is sufficient show a reduction in noise
impacts that satisfies the requirements of the Resolution.
Noise Abatement. The Port showed that its noise abatement programs have produced reductions in
on-the-ground noise measured by a variety of different metrics that are related to adverse impacts for
many people throughout the region.
The Port stressed the reduction in aircraft DNL over the years because the relationship between DNL and
human "annoyance' is well accepted in the airport industry and the scientific world as the best aggregate
indicator of adverse noise impacts. As the majority puts it, "[a]ircraft and total DNL metrics are the
principal tools used to summarize the overall changes in environmental sound levels associated with
airport operations.’ Measured aircraft DNL around the Airport has fallen by 2.8 dB since 1986, 3.4 dB
since 1989/1990, 2.3 dB since 1992 and 0.9 dB since 1993. These reductions can be expected to be
related to significant reductions in the numbers ofpeople "highly annoyed’ by aircraft noise, on an
aggregate basis, even ifthe difference in sound levels, occurring over time, might not be distinguished by
an individual observer.
The Port supplemented its analysis ofDNL with a review of on-the-ground measurements using the TA
45 of 50
reduction in the
and SEL metrics that confirm that there has been, as enacted, a significant
and adverse noise
highest-noise-level aircraft events. While the relationship between these metrics
in the loudest events,
"impacts" is less well understood, the Port has shown that reductions
[PAGE 44]
reductions in both "high level"
which are segregated by these metrics, can be expected to be related to
speech interference and, possibly, sleepdisturbance.
Port's noise abatement efforts have not
The majority ofthe Panel has nevertheless concluded that the
ofthe
produceda sufficient reduction in real, on-the-ground noise impacts to satisfy the requirements
I do not believe that the
Resolution. While I greatly respect their thorough review and technical analysis,
General Assembly intended us to apply a standard so exacting as
ofthe significance ofthe noise
they have used and, therefore, I cannot accept their ultimate assessment
reductions the Port has shown.
the population exposed to different sound
The reliability ofthe Port's technique ofimputing estimates of
incremental changes in noise exposure into
environments over time, and the methods it used to convert
to serious
estimates ofreduced annoyance, speech interference and sleep disturbance, are subject
real noise impacts," the General
reservations. But when it called in the Resolution for "measurement of
scientific proofthat
Assembly did not require, and could not reasonably have expected, rigorous
be related to particular
incremental, measured improvements in on- the-ground noise levels can
to be "meaningful."
reductions in noise "impacts" that could be said by some objective measure
established scientific methods" for
Based upon the evidence offered to us, I would find that the
estimates ofthe significance of
assessing the impact of aircraft noise are not designed to provide precise
definitive DNL threshold for
incremental changes in noise exposure over time and do not establish a
measuring meaningful aircraft noise reductions.
the 3.4 dB reduction in aircraft DNL shown by the
The majority ofthe Panel has nevertheless found that
in terms of producing a real, appreciable reduction in
Port is "below the threshold of 'meaningfulness'
when that DNL change occurs over a period
airport noise impacts for an affected population," especially
The majority concluded, therefore, that the
of six years and is coupled with an increase in operations.
sufficient reduction in real, on-the- ground noise
Port's noise abatement efforts have not produced a
A-93-03.
impacts to satisfy the noise condition ofResolution
reduction” on the Part. When the Resolution was
This approach imposes an "unrealistic standard of noise
reductions in noise levels would
enacted, it was to be expected by the General Assembly that (i) any
that at the same time, aircraft operations would
occur incrementally over a period ofmany years; (ii)
tools like the FICON Curve ‘cannot provide
increase; and (iii) that, as the majority recognizes, analytic
reductions in DNL" that could be expected to be
robust estimates ofthe population impacts ofthe small
it is unreasonable to impute
realized by the Port's noise abatement programs. Under these circumstances,
measured
that the Port should show a reduction in noise levels,
to the General Assembly an expectation
resolve scientific doubts about its meaningfulness,
by DNL or otherwise, so significant that it would
I cannot accept my colleagues’ conclusion that
before the third runway would be authorized. Accordingly,
reduction in noise impacts.
the Port's noise abatement programs have not achieved a meaningful
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Noise Mitigation. I must also distance myself from their assessment ofthe Port's insulation program. As
they acknowledge, the Port has done an "impressive job" on its residential noise mitigation programs
since the Resolution was enacted and has provided appreciable benefits to thousands of residents ofthe
Region. The Port has already insulated 3,647 homes and is continuing
[PAGE 45]
its accelerated program of insulating about 110 homes each month. There is no dispute that this program
provides noticeable and meaningful indoor noise reductions.
While the majority applauds the success ofthe Port's noise mitigation program, it focuses on the Port's
failure to accelerate the pace ofthe residential insulation program before the Resolution was enacted and
to implement a coniprehensive program for the insulation of public buildings. I share their concern,
especially about the public schools, but for me the determinative facts are (i) that thousands of residents
have benefited from residential insulation; (ii) that since 1993, when the Resolution was enacted, the pace
ofthe Port's residential insulation program has accelerated to an "exceptional" rate, as the majority puts
it, that is almost four times faster than the rate contemplated under the Noise Mediation Agreement; (iii)
that in recent years the number of sensitive-use public facilities (schools, hospitals, churches, and
libraries) within the loudest noise contours has been markedly reduced, and (iv) that the Port's failure to
insulate the many primary and secondary schools in the Highline School District cannot Properly be
charged to the Fort's account in this proceeding, because the Port has agreed for some time to fund the
insulation ofthese schools and its offer has been refused.
The Port's noise mitigation program has provided significant benefits to thousands of residents ofthe
neighborhoods most adversely affected by airport noise and has contributed to, not detracted from, the
achievement ofa meaningful reduction in noise impacts.
Reasonableness. The significance ofthe noise reductions
scheduled, pursued and achieved by the Port has properly been the focus ofthe Panel's hearings, its
deliberations and this Final Decision. But as the Panel previously interpreted it, the Resolution has both a
"meaningfulness" requirement and a "reasonableness" constraint. I believe that the General Assembly did
not intend to give up its plan "vigorously" to pursue the runway, even if the Port's noise reduction was
not sufficiently "meaningful" to satisfy a majority ofthis Panel, unless there was clear and convincing
evidence that the Port could reasonably have been expected to have been able to schedule, pursue and
achievea significantly more meaningful reduction in noise impacts than it has shown.
The community advocates (and at various times, each ofthe members ofthe Panel) have raised questions
about noise abatement and mitigation measures that have not been scheduled, pursued or achieved. But
the opponents ofthe runway have not met their threshold burden to show that in spite ofwhatever legal,
operational and practical constraints it faced, the Port could have undertaken additional noise abatement
or mitigation programs that could reasonably have been expected to produce a material change in noise
impacts during the pertinent time frame (that is, they would have made an otherwise insignificant
reduction meaningful), given the approach to assessing "meaningfulness" adopted by the majority.
While a rigorous analysis ofthe impact of potential alternative noise measures would have been desirable,
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to "schedule,
the evidence presented to the Panel does not show that the Port squandered opportunities
reductions in noise impacts after the Resolution was
pursue or achieve' significantly more meaningful
that it would
enacted in 1993 and, in the words ofthe majority, "served notice to the Port ... have to
ofmeaningful, measurable,
show that its noise programs were, in fact, producing results in the form
on-the-ground reductions in noise impacts."
reduction in DNL they imply would be
I take little comfort from the majority's speculation that the 5 dB
well be achievable." The Port has
necessary to satisfy the Resolution "might very
[PAGE 46]
that have been most
scheduled, pursued and achieved the objectives ofthe noise abatement programs
and should, continue to
likely to produce a meaningful reduction in noise impacts. ‘While the Port can,
there was no evidence before
find creative ways to reduce the burden of aircraft noise on its neighbors,
reduction in DNL without imposing
the Panel that the Port could have caused a significantly greater
federal policy and with the
artificial capacity constraints at the Airport that would be inconsistent with
of regional airport capacity.
core objective ofthe PSRC Resolution: the expansion
decision to authorize the third
Conclusion. I doubt that the General Assembly contemplated that its
the success of the Port's unprecedented efforts to use
runway under the Resolution would depend upon
of measured
established scientific methods to convince a panel of experts exactly how the impacts
the Panel had to
reductions in on-the-ground noise can be expected to benefit the community. Ultimately,
Fidell (for the ACC) recognize is a
resolve what both Dr. von Gierke (an expert for the Port) and Dr.
" scientifically accurate" judgment,
social economic, or political question, not a search for an elusive,
to satisfy the
about whether the noise reductions shown by the Port were sufficiently "meaningful"
ofthe Port's noise abatement
Resolution. I am convinced that given the achievement ofthe objectives
measured on-the-ground noise shown by the Port that resulted from the
programs; the reductions in
the insulation ofthousands ofhomes,
accelerated reduction in Stage 2 operations, especially at night; and
the Port has met its burden.
meet its obligation to reduce the
The Panel's focus has been on what the Port has done in the past to
ofthe Panel ultimately reached different
impacts of aircraft noise on the community. While members
the need to find new ways
conclusions about the Port's success, we all recognize that in the future,
number of aircraft operations at Sea-Tac
effectively to reduce aircraft noise impacts will intensify as the
continues to grow, with or without the new runway.
reduction in noise impacts in the past by
The Port was able, in my judgment, to achieve a significant
In the future, that approach is
reducing noise levels at their source: the aircraft that use the airport.
control the noisiness of aircraft, the number of
unlikely to be effective. The Port has little, if any, ability to
must seek creative approaches to
operations, or the flight tracks they use. The Port and the community
controversial than reductions in aircraft noise
noise reduction that take new forms, even ifthey are more
that come at the expense of commercial airlines.
the Fort, the FAA and the WSDOT --
The members ofthe "Coordinating Committee the PSRC itself,
work together to achieve future reductions
have, it seems to me, both an obligation and an opportunity to
confident that I speak for the entire Panel in
in noise impacts that have not been realized in the past. I am
institutional barriers between the Port and local
urging the Coordinating Committee to overcome the
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