Here's the deal. I called Scott Stroud and he told me that he would show me where the full pipes were located. I was stoked. Scott was excited just to have someone come out and ride the pipe. He said that no one rides them anymore. I encourage you to call him if you go.
The pipe I rode looked to be about 20 foot in diameter. Scott said they are ridable from December through March sometime. The pipes aren't smooth like a grindline park. Nope. They are very rough like worn concrete, with a little algae dust thrown in. So, road wheels are a must. Second thing is that they slope down, about 200 foot long. And at the bottom is water. So, if someone skates, another ought to stay near the bottom to catch a loose board. Otherwise the board is lost in the water. Oh, it echo's as one skates, and it's loud.
Follow I 90 to Moses Lake
Take the second exit.
North on the "I-90 loop"
Right turn at Wheeler Road, which becomes 3rd street.
Left turn at "N" NE
Right turn at 6th NE (becomes a Gravel Road)
Left turn before Bridge.
Follow dirt road next to canal, north until you see it stops, that's where the pipe is.