  Pipe-welding scenes in 21st Street water-line project.. ABOVE, LEFT: Dave Dunn of Global Underground with the McElroy T900 machine. ABOVE, RIGHT: Global Underground foreman Bryan Southard uses the weight of his backhoe bucket to help line up a section of the 20-inch-diameter HDPE pipe into the T900. Westside Pioneer photos
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Bryan Southard, project foreman for Global Underground, announced the specific target date this week. A tentative mid-December time frame had been set previously for the work between Lower Gold Camp Road and Villa de Mesa Drive.
Starting in early September, the work has allowed the normal two-lane traffic most of the time, but the resultant narrowing has temporarily eliminated the street's center lane.
A highlight of the current work is the fusing of 40-foot segments of 20-inch-diameter high density polyethylene (HDPE) pipe into lengthy spans for installation under 21st Street. Passersby could view this operation this week alongside 21st, just south of Lower Gold Camp.
A hydraulic fusion machine allows the pipe ends to be matched up exactly, shaved to allow a clean connection (this is aided by hand-applied isopropyl alcohol) and heated to well over 400 degrees. The heat expands the molecules at the pipe ends, rendering the HDPE temporarily gelatinous at that point. “We squeeze both molten ends of the pipe together in a giant smush, and it thinks it's one pipe,” explained Dave Dunn of Global Underground.
   Pipe-welding scenes in 21st Street water-line project.. ABOVE, LEFT: A preparatory step is removing the rough edges and oxidation at the pipe ends (note shavings at side). ABOVE, MIDDLE: A heating unit is placed between the two pipe ends for about 10 minutes, until their temperatures rise above 400 degrees and they (the ends) become gelatinous. ABOVE, RIGHT: The extremely hot ends are pressed together to make a watertight weld. Westside Pioneer photos
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The machine, a T900 model made by the McElroy company of Oklahoma, would sell for nearly $200,000, “bare bones,” Dunn said.
Once the sections of fused pipe total the right distance, that segment will be installed under 21st, using a “pipe-bursting” technique that allows the 20-inch line to replace a 42-year-old, ductile iron 16-incher without the expense of having to dig the old one up. (See Nov. 24 Westside Pioneer for details.)
Westside Pioneer article