I went on an aerial search last night until about 0200 local. We were looking for an intermittent emergency signal (121.5 Mhz) which the Air Force satellites had been tracking most of the day without success. It was up and down the north west Washington area. Started in Skagit county and later was plotted in Semiahmoo - near Blaine and just north of my house. I had a concern that it might be one of mine but it wasn't. That would have been embarassing to say the least to get called to search for a signal at my own house. We started our search by flying to Blaine but got no signal there. We did pick up a signal on the way though. We then headed to the Bellingham marina area and the signal peaked and faded again as we arrived there. Then we looked at the hospitals in the area thinking that one of their helos had landed hard or something. Tried a small private airport near Ferndale. Sandy Point, Lummi Island, no dice. We finally located the signal as emanating from a local transfer station just north of Bellingham. We drove there to confirm it but were unable to get in to shut it off because of the hour. It is probably shut off now as the authorities were planning to find it this morning. We figure that someone had discarded an EPIRB or ELT without deactivating it and it got switched on in the garbage truck somehow by being jostled around. The garbage truck was probably tracked for a good part of a day as it travelled around giving the AFRCC fits. Moral of the story: Do not discard an EPIRB without deactivating it first. Remove the batteries and / or smash it real good first. If in doubt give the CG or local search and rescue folks a call (during the day, please) and they will no doubt help you. There were a dozen or more people working the one last night until the wee hours. I only spent four hours myself flying and driving around but it can be dangerous and difficult work for a lot of folks. EPIRBs do get attention regardless of what some people say.