So I finally got a chance yesterday to look at the tank. Thanks for all the responses guys, I really appreciate it. I'm not the contractor, I'm just providing the crane to lift the pipe up, but the welder doing the pipe work, just calls me and says "hey, how we gonna do this?" I just charge by the hour while I'm there with the crane.
The tank is actually closer to 80' tall (by my rusty trusty eyeball), and the pipe we're replacing is actually the overflow pipe. If they are pumping into the tank, and the shut offs don't work, this releases the water back out of the tank onto the ground. The tanks get inspected as public water systems, and if the pipe is rusty, it needs to go. The bad part is the inside inspection and painting of the tank. I'm sure they scaffolded it when they built it years ago, but they're gonna have a fit on what it will cost now.
The ladder starts about 30' up the side-no cage- no rest platforms-so I didn't climb it to look for roof hatches, but from a distance I can see no hatches directly above the overflow pipe. The one picture shows the bottom access hole, thats my 2AA mag lite setting on it for a reference of size. I don't think my 11year old boy could fit through it. In the third picture, the pipe we're replacing is on the right, the ladder is on the left.
Its also kind of handy having the power lines close for working. Thanks for the confined space comments too Tiny- that had slipped my mind also.
I think the best option right now is welding/installing a new 3'x3' roof access hatch right above the overflow. Weld it in first, replace pipe, manbasket through hatch to inspect welds and paint, and paint underside of new hatch from on the roof.
