Minutes Nov 28

The committee had requested that the noise model results be available for review at this meeting. HMMH did not have the model completed.

Daren brought an aerial view of the Aurora Airport and surrounding area, expanded several miles to the north and south to better display the airport environment that might be affected by noise. The map will be used for an overlay of the noise model when it is completed to show the relationship of neighborhoods to the patterns and noise impact.

HMMH had requested that the committee review assumptions which they are making as inputs to the noise model. Daren passed out copies of this document and it was reviewed by the committee. Attached to the document was an aerial view with the departures and arrivals overlaid, giving a better idea of traffic over populated areas, however it was in black and white and difficult to analyze. We are expecting a color version to be provided which can be put onto the website.

HMMH is proposing a workshop in January to discuss the noise model and the results with the committee, then to conclude the study in February. Nick requested that we get the model results sooner, ideally by December 19th for the committee review at the next meeting. The committee agreed that we must have the data before the workshop is held.

On December 19th, the agenda will include reviewing the model, and generating questions and additional information to understand the model prior to the January workshop.

The assumptions in HMMH "Modeling Parameters and Assumptions" were discussed. The committee agreed that more Columbia Helicopter information be included. They challenged the number of GA helicopter operations as 60 per year seemed low. The number of Twin operation in winter seemed low and was proposed to be increased. Operational differences on weekends versus weekdays were discussed. For example, less corporate traffic on weekends, more training. The percent of touch and goes was listed as 7% - 23% of total operations. The committee asked for clarification from HMMH.

Daren made a list of the specific clarifications and changes requested as documented in the email exchanges below. HMMH responses are included.

Email from Daren to the Decibel Committee Friday, November 30, 2001 10:58 AM
To the Decibel Committee. Response from HMMH included

Greetings everyone,

Below is a response from HMMH regarding the questions that were raised at
our meeting Wednesday night. I think they adequately answered our questions
with number one being the exception. Technically, the Columbia Helicopter
facility is not on the airport. They do have a maintenance hangar on the
airport, but that is all. I think we can get operational data from Columbia
if we request it, however, we need to understand that the results of this
study will not impact how Columbia flies into and out of their facility.
Aside from the helicopters flying between their facility and the maintenance
hangar. And that activity does not likely create noise impacts beyond the
airport.

I would like further input from DECIBEL on the need to include Columbia
Helicopter off-airport activity in this study. Additionally, HMMH explained
how they reached their assumptions and advised us to make any changes now. I
think the group mainly wanted further clarification on how the assumptions
were reached and an acknowledgement that a three-day snapshot of activity
isn't necessarily a totally accurate depiction of traffic levels. I think
HMMH understands that, and has put together the most accurate estimate that
they can.

Aside from the Columbia Helicopter issue, I would like to advise HMMH to
proceed with the modeling unless there are any objections from DECIBEL.

Please respond to me on the Columbia Helicopter issue by the close of
business on Monday so I can advise HMMH.

Thanks,

Daren
-----Original Message-----
From: Eugene M. Reindel [mailto:ereindel@hmmh.com]
Sent: Friday, November 30, 2001 10:32 AM
To: GRIFFIN Daren A
Subject: RE: modeling

Daren,

Thanks for the response. The measurement report is likely to be to you
early next week. The report will summarize both measurement periods. I
think you and DECIBEL will get a lot of valuable information from it. As
far as the modeling and the modeling process, we will likely begin modeling
as soon as the three comments are addressed and you are satisfied with our
response. When we deliver the results of the modeling effort, we will
include what information went into the model, the model validation
(comparing measured levels - single event and cumulative), and explaining
the results. I hope that will satisfy your needs. We will also explain
what the model is and what it does.

Now to address the comments:

1. I understood (perhaps incorrectly) that Columbia Helicopters did not
operate at ASA and therefore were not to be considered as part of the ASA
activity. I understood this from our earliest conversations with you during
our first tour of ASA. If this is not the case, we can certainly add
Columbia Helicopters into our modeling, but we will need more information
from them in regards to their annual activities. Please direct us ASAP, so
that we can determine what information we need from them and how we are
going to get it.

2. We understand that we had only a snapshot of activity while we observed
the observations. We also understand that we still only had a snapshot of
activity during the weeklong measurements where we obtained operation counts
from the on-airport noise monitors. This is why the surveys went out. We
used all of the information obtained, including the Master Plan update, to
derive these counts. This is our "best" estimate. It is an estimate, which
is the reason for having you and DECIBEL review it. If you believe we need
to make changes to our assumptions, now is the time to do it.

3. The 7% to 23% for touch and go operations was what was observed during
our time there. It shows the high variability in the percent of touch and
go activity on a daily basis, which goes back to your first comment. Again,
we used more information than just our observations to derive the final
numbers. Of the 92,100 operations, we are estimating 25% are touch and go
operations. If our assumptions are wrong, then now is the time to change
them. This will not affect the number of operations (arrivals and
departures), it will only change how many go around the pattern and stay in
the local area of ASA.

Our modeling work will produce cumulative noise exposure contours and single
event noise contours overlaid on the aerial photo that the flight tracks
were presented. Please give us feedback ASAP and let us know if we are
directed to begin the modeling process. Eli and Bob are anxiously awaiting
approval to begin the modeling process that will produce the long-awaited
noise contours for years 2000, 2007, and 2017 (all unabated).

We are looking forward to hearing from you and proceeding with the modeling
effort on this project.

Gene Reindel

-----Original Message-----
From: GRIFFIN Daren A [ mailto:Daren.A.Griffin@state.or.us
<mailto:Daren.A.Griffin@state.or.us> ]
Sent: Friday, November 30, 2001 8:26 AM
To: Eugene M. Reindel
Subject: modeling

Good Morning Gene,

The DECIBEL meeting went fine. They liked the idea of a mitigation workshop
with HMMH. However, they want a chance to look over the data before getting
into that workshop.So we will be meeting in December. At that meeting I need

to have the measurement results from the November monitoring. Also, the
model and explanation of the modeling process. As much information as you
can give me for that meeting would be great.

Then, DECIBEL can come up with their list of questions and you can answer
them prior to our January workshop.

As far as the modeling assumptions go these were the comments:

1. There was general concern that Columbia Helicopter activity is not being
taken into account. It appears all their activity was removed from the
assumptions. Can you explain how their large helicopter activity is being
accounted for?

2. There was a lot of discussion over the assumed operational level.
Overall, your assumptions were accepted. However, there was concern that the
three day observation periods wouldn't fully represent actual activity
levels. Example being on the weekends there are increased touch and go's but
less corporate/business jet activity because that occurs on weekdays.
However, there is more overall traffic volume on the weekends because more
private pilots are flying. Can you explain how the modeling process takes
into account these factors?

3. On the bottom of page 3 Touch and Gos are indicated to be 7%-23% of
operations. It is unclear as to what that means. Can you clarify?

That was basically it for questions/concerns. The group expressed a desire
to have some visual aids to be able to look at and see noise impacts. Will
that be available as part of the model? Will you be using the aerial
photographs?

Thanks.

Daren