“Basically, it's just labor and materials,” says Dan Mathews, assistant superintendent for the department's Water Transmission and Distribution Division. “Our labor is a fixed cost, and the materials are small change compared to doing an open cut. Restoration is also minimal. And because we do it ourselves, we're experts. This means the crew is quick and efficient.
“Plus, they care. This is a dedicated crew, not only in that they just do this one job, but because they are also responsible professionals.”
The crew consists of five employees doing the job from beginning to end, including digging, running the machine to split the old pipe and feed in the new pipe, tying in the new service to the home, and replacing the soil, sod, and any other patching. On a typical day, the crew installs 300 to 500 feet of new pipe.
“Our largest pull was 550 feet,” Aguiar says.
When crews run into gas and other utility lines, they bypass the lines as easily as possible without disturbing them. “Because we're not in there with heavy equipment, we can control the path and the speed of the installation,” Aguiar says. “That gives us a real advantage.”
“Because it's being replaced in 500-foot coils, even long runs can be one, joint-free continuous piece,” says Bruce Kuffer, PE, manager of polyethylene market development for the Plastics Pipe Institute (PPI). “When connections are made to homes, or pipe sections added, they are literally fused together, which makes the system leak-free. This seamless, jointless system provides a longtime solution.”
The average temperature in Miami is in the mid to high 80s. With the coils sitting out in the supply yard exposed to intense sunlight for long periods of time, it's important that the pipe have proper UV protection.
Aguiar chose Endot Industries' Endo-Trace pipe because of its minimum five-year Florida Sunlife Ultraviolet Protection Rating and its tracer wire, which will make it easier for crews above ground to find the buried pipe. The product is supplied by HD Supply Waterworks of Thomasville, Ga.
According to PPI, splitting an old pipe and inserting HDPE pipe costs one-third to two-thirds less than traditional dig and replace, although Miami-Dade declined to disclose local figures. Because of the longevity of the new pipe, savings generally may be as much as 300%.
To fuse sections of the plastic pipe, the ends are inserted into the clamps of a fusion unit and trimmed. Then they're held against a heat plate, which is removed when the proper melting point is reached. The ends are then pushed together and held until the joint is cool.