Page 9 - Winter 2009

MINNEAPOLIS, EAGAN, AND RICHFIELD VS.
THE METROPOLITAN AIRPORTS COMMISSION
Paul Schomer
Schomer and Associates, Inc. Champaign, Illinois 61821
and
Jack Freytag
Freytag and Associates, LLC Newport Beach, California 92660
Introduction
“The outcome of the litigation was a negotiated settlement of $128 million for sound insulation in the 60–65 DNL zone.”
The Minneapolis–St. Paul Airport
(MSP) is situated adjacent to older
residential areas of the city of
Minneapolis and bordered on other
sides by newer suburbs including Eagan
and Richfield. MSP opened a new run-
way in October 2005. Local communi-
ties surrounding the airport agreed not
to fight the new runway with the prom-
ise that the airport would provide sound
within the 60–65 day-night average sound level (DNL) zone. After making this promise to the communities, the airport reinterpreted its commitment and several lawsuits ensued from those affected. This paper describes one of two major lawsuits brought by the affected cities against the Metropolitan Airports Commission (MAC), the commission that runs the commercial airports in the Minneapolis–St. Paul area including MSP. There also was another lawsuit brought by citizens of Minneapolis that dealt with the effica- cy of the environmental impact analysis.
This law case pits the city of Minneapolis and two sub- urbs, Eagan and Richfield, against the Metropolitan Airports Commission. There are two main technical issues to this case. First, MSP noise adversely and significantly affects the “quietude” in residential areas that are in the DNL zone of 60–65 dB. Second, a 5-dB noise insulation package for homes in this DNL zone will ameliorate the situation.
To provide the technical foundation for this law suit, Schomer and Associates, Inc. and Freytag and Associates, LLC were asked to develop the technical background and arguments requisite for the city of Minneapolis to prevail. Four general tasks were established for the consultants—(1) define “quietude,”(2) show that, absent MSP noise, the resi- dential areas in the 60–65 DNL zone generally enjoyed qui- etude, (3) quantify the impacts of MSP noise on annoyance, speech interference, and sleep disturbance throughout this zone, and (4) quantify the benefits of a 5 dB noise insulation package. Both consultants worked on all parts of this study, 1–4, with Paul Schomer taking the lead for tasks 2 and 3 and Jack Freytag taking the lead for task 4.
Major points to be established: (1)Define “quietude”; (2) Show “quietude” exists absent MSP noise; (3) Quantify the impacts; (4) Show that a 5dB package of noise mitigation in homes would ameliorate disruption of “quietude.”
Major points
(1) Define “quietude”
We first established a definition of “quietude,” the term used by the Minnesota State Legislature in develop- ing a law protecting the natural noise environment in land areas of Minnesota. Initially, the law was used primarily in parks and wilderness set- tings but for this case the law was used
in residential areas. Thus, we had to establish a definition of quietude for the court. The definition established was the fol- lowing—(1) The DNL is in the range of 50–55 dB, (2) Rarely are there noises at night with the potential to awaken some- one, (3) One can use the indoor and outdoor areas of their home without any noise annoyance issues, and (4) One can have the windows open or closed as they wish without envi- ronmental noise problems.
(2) Show “quietude” exists, absent MSP noise
Having established the definition of quietude it was then necessary to show that, absent MSP aircraft noise, quietude exists in the residential communities surrounding the airport that were the subject of this lawsuit. To do this we had to do two things. First, we had to separately measure the day time and night time residential noise environment in these com- munities without including airport noise. Second, MSP has an environmental noise monitoring system in the DNL 60 – 64 dB zone that reports total noise—airport noise and what they term non-airport (or community) noise. It was neces- sary for us to explain to the court why this airport noise mon- itoring system generally overstates the true community noise contribution (i.e., without airport noise) frequently and sub- stantially.
(a) The measurement sampling strategy.
Obviously it is impractical to measure throughout the large, residential, DNL 60–65 dB areas continuously for long periods of time. A sampling technique was required. Thus it was necessary to show that the random sampling procedure employed would serve to demonstrate the community noise without the airport noise included. To do this, we chose to perform random time- and spatial-sampling within the study area—the residential area defined to be in the 60–65 DNL zone and not already noise-insulated. We selected twenty five
8 Acoustics Today, October 2009
insulation to homes