The state’s worst underground gas pipes could be replaced within two years.  Railroad Commissioner Michael Williams says there is a problem with old steel natural gas pipes.  “You have the largest number of leaks on the body of the pipe followed by leaks at the meter follwed by leaks at the riser followed by leaks at the couplings.”  He says there are over two million of them but his idea would mainly target utilities that have 25 percent of their lines leaking over a three year period.  Those utilities would have to replace those leaking steal lines with plastic ones within two years, with the idea of cutting down on leaks and explosive accidents.  The commission just heard a rough presentation of the idea.  It will look at more details next month.