The noise estimations in your first link show the estimated noise in Ens which is 18 miles out and directly below the approach path at 40 dB, and for a more pathological case in Wezep 20 miles out at 45 dB. For reference that's somewhere between "noise at the library" and "quiet suburb"[1].
If you search for "Projectie Route" you can see graphs showing that the estimated approach and departure paths, planes coming in for landing are at FL60 5-10 miles out, planes departing are climbing past FL30 10 miles out.
I'm not dismissing the fact that some people in close by bedroom communities are going to be hearing airplanes regularly, but this claim that it's going to be an issue for anyone even 20 miles out is nonsense, let alone 100 miles out.
Ghent in Belgium is around 100 miles from Amsterdam, planes just crossing the Dutch-Belgian border aren't at FL50 as if they were on their final approach to Schiphol.
1. http://www.industrialnoisecontrol.com/comparative-noise-exam...
Basically, Schiphol is getting too crowded so they are opening a second location (actually, it already exist but it's a small airport now which mainly services small private planes) in Lelystad. As the new location is relatively close to Schiphol (about 32 miles) the new inbound routes and holding patterns have to be below the existing routes for Schiphol because there simply is no other place for them to go.
Plenty of information about it available online but most of it's in Dutch. This report has a couple of maps and charts which may be useful for you: http://hoogoverijssel.nl/wp-content/uploads/2017/07/20170711...
Edit: and some more info: http://www.pbbo.info/documenten/Luchtruim%20Lelystad%20ACS.p...