Tampa-The Mosaic Co. was in the process of replacing the last four miles of a 12-mile-long water pipeline that runs from Lithia Springs, which the company owns, to the Riverview plant. The company said the original steel pipe was placed in the 1940s and had been repaired at various times over the past several decades. The new pipe is made of PVC and should last for several decades. The project will take 14 to 18 weeks to complete.