Hi springhillflyer
I have been flying RC planes for about 38 years. I do not believe the Hydro lines are causing radio interference. All of th planes I fly now are made of COROPLAST corrugated plastic sheets. Many are built with aluminum structural tubes. I make certain the receiver antenna wires are at least 1 inch away from the aluminum pieces. I have heard of radio signals bouncing off metal buildings and causing some interference. At our field we have metal buildings that we fly over during the landing approach and there has been no reported problems. Make sure you ALWAYS do the recommended radio range check prior to takeoff. Make certain your batteries are well charged. Make certain your radio gear is up to date. I use Futaba 2.4 equipment. Never a problem.