The north end of West Seattle (Alki, North Admiral) is experiencing a constant cycling droning sound that sets up a vibration in some homes. Does anyone Know what is causing this droning? It is a 24/7 noise/vibration so it is not coming from a daytime construction project and is not aircraft noise. Ear plugs don’t help because of the vibratory aspect of this noise. It is hard to hear outside but causes humming, droning in sructures. Help. Thanks