I am building a pond. Hope to start moving dirt in about 4 weeks. I've been told I need a drain. Looks like with pipe and valve that could cost $3000 or more. Is it worth it? Do I need the drain at the bottom? I'm impounding 19ft of water. Valve suppliers are telling me they have 12 ft stands or so - not 19.Should I be using steel or PVC? I will need about 180 ft of pipe if I put it at the bottom. Years from now will I want to just draw it down or why might I want to completly drain it?