I hope the Assembly and areawide residents will take to heart this vital sentence from the Baker "Alternative Heliport" study: "A proposed solution that reduces noise for 1,000 people, but does so by inflicting an increased noise level on 600 others, would not be a solution at all."
As the Assembly pursues alleviating flightseeing noise, that statement will need close attention, or it could become a prophesy for the Montana Creek site.
While Dupont's issues seem few so far, there are many serious concerns about a Montana Creek site.
Most importantly: More sound tests are needed. Baker tested with only one helicopter. One helicopter does not create the sound levels squadrons of three to five impose. Plus the Baker readings were on a high ceiling day so the readings don't reflect low-ceiling impacts.
Sound test science shows when two helicopters fly together decibel (dB) readings increase about 3dB and a 3dB increase is actually twice as much sound power. What will the accumulated sound power feel like when five helicopters fill subdivisions and recreation areas with their accumulated reverberations?
Per Baker: If the result is "inflicting an increased noise level ... it would not be a solution at all."
A common misstatement is that the Montana Creek flight paths have no homes in the noise corridor. Not so. Even with only one helicopter in flight, Baker says: "We estimate the noise levels at the edges of the 3,000-foot corridor to be about 65 dBA [the level that starts to interfere with conversation] and at the edges of the 6,000-foot corridor, it is estimated that the noise level ... would be about 55 dBA [the level where aircraft are clearly audible]."
At the "edges" of those corridors are the residential subdivisions of Montana Creek. Hundreds of people - easily 600 - live there. To them, add other residents and tourists who frequent the trails, glacial hikes, campgrounds, and water activities on the lake side of McGinnis.
If all flights could go on the back side of McGinnis (and if the heliport itself were far enough from residences), then concerns would diminish. But airport records indicate ceiling height requirements will limit back side trips to only about 50 percent of summer days. The other 50 percent would have to be on the residential-recreational lake side. Plus, unless regulations prohibited circular routes, tours might choose the lake side for half their flights even on good days, bumping lake-side sound impact up to 75 percent of all flights.
With the "edges" of just one helicopter's noise at the 65dB level (conversations interrupted), flights 50-75 percent of the time on the lake side of McGinnis would certainly be unacceptable. But even 55 dB may be too much for constant day and night flights.
Another concern is the heliport ground site location. One proposal is just past the pedestrian bridge at end of the road. From there, Community Garden readings were 50-56 dB. With the garden less than one-half mile to subdivision homes, that puts all takeoffs and landings with only one helicopter clearly audible for many residents.
Already Realtors disclose that rifle range noise may be objectionable to some buyers. What might happen to quality of life, and property values, if the heliport site itself crowds acceptable sound levels at residences?
Relief of noise impacts within the borough is a necessary goal. Doing it well without simply shifting the problems to another location is equally necessary.
Before proceeding, many well-advertised squadron flight tests must be done, day and night, at all flight elevations.
And if, after all the tests, many residents say "no" to a Montana Creek site, then it must not be built.
If Dupont has readily solvable concerns, I'd recommend this: Build Dupont first. Operate it several years with all southern helicopter and float plane flights out of it. For northern routes alleviate sound as best as possible from existing sites: Vary flight paths, heights, etc., so various neighborhoods each share a bit of the noise (instead of compounding all noise at Montana Creek alone). Integrate quieter helicopters as possible.
Then, after several years, reconsider. Resurvey. See if the public wants to spend what it takes to build another site. Only then do squadron sound tests at Montana Creek to see, then, if residents' results deem it a possible site or not.
Perhaps by getting the channel corridor quieter via Dupont for southern routes, and amelioration efforts alone for northern routes, a northern heliport could become unnecessary.
Sara Boesser lives near Skater's Cabin and cherishes the area's natural beauty and quiet.