This spring I had a muskrat tunnel down next to my vent and into my siphon pit. I had to dig it out and make sure the tunnels didn't cause any problems with my dam. Luckily it was just in the area of my pit. So while I was doing repair work, I decided to make some modifications. One of the problems with a single vent with 2 drain pipes was that at the start of siphon mode, my pipes would alternate the siphon until the water level raised a little more. It still went into full siphon mode, but probably allowed my water level to raise faster then it would have with two vents. So I modified it so each pipe has its own vent. I would recommend that if you go with dual pipes. I also made my pit with a concrete bottom and concrete blocks all the way to the surface as I never thought a muskrat would get into my system. I'll load some pictures of the finished product here soon.
