Three years ago I had my house's septic tank replaced, and the guys put in new cleanouts because they couldn't find the original ones. Well, by chance I just found them: buried under about 6" of dirt and rocks about two feet away from the house.
What should I do with them? Abandon them because there are now new cleanouts? Or add some PVC risers to make them accessible at grade level? And if so, how should I make the connection between the old cast iron pipe to a new 3" PVC pipe? A no-hub coupler wouldn't work since the exposed cast iron pipe is flanged.
Best Answer
My personal style is to leave them 6" deep with carefully positioned annual flower beds on top of them - give those beds rock walls, if you like, and document the heck out of it. But if you'd rather extend them to surface:
Those plugs have pipe threads, so a PVC to MPT adapter in the correct size seems the obvious solution to connecting PVC to them.
I guess annual flower beds may not work so well in the desert - idea being to have a surface feature that maps to the subsurface feature of interest. You need a gazing ball right there, say. This method is subject to loss of documentation and/or memory.
A "hand-hole" would be another approach. Leave the plugs in place and extend access to the surface. You might know them as sprinkler-valve-boxes - a bottomless box with sides and a lid, in plastic or concrete.