Seismic-Prone Project Area Requires HDPE

September 2008 Vol. 63 No. 9

For the Big Bend project, new water mains for the project area were specified to be HDPE DR11 DI OD and were 460 meters in length. Laterals to the site structures accounted for an additional 800 meters of pipe ranging from 150 to 250 mm diameters. Sanitary sewer lines were all low pressure force mains and constructed using 400 meters of HDPE DR26 along the main road and site right-of-ways. Included were four flush out chambers on the main and three additional flush out chambers on the laterals to the site structures adjacent to the right-of-way. Sanitary servicing to the remainder of the site, not adjacent to the right of ways, required an additional 165 meters of HDPE DR26, and PE series 75, including the laterals to the individual units.

The building construction program was on going throughout the $730,000 utility installation, creating an even more challenging work environment for the installation crew. In order to ensure access to the site for other contractors, only certain lengths of pipe string could be pre joined. This meant that some of the HDPE fusion welds had to be done in the trench, requiring a fusion machine that could perform complicated ditch welds and fusion of fittings.

In addition, the flush out chambers on the sanitary lines required a riser that could be accessed by a flush truck for maintenance purposes, creating a space problem. Some of the HDPE fittings had to be customized and re welded in order to fit inside the specified 1,500 mm diameter barrel of the chambers. A Connectra Fusion 14 inch hand pump machine was used both in and out of the trench to perform all of the 230 required fusion welds for the project. “There is no question this was a complicated job when it came to joint fusion,” said Warning. “The fusion machine was perfect for the job because of its adaptability and ease of use in tight spaces.”

In total, 2,800 meters of pipe ranging from 2 inch to 10 inch DIPS were fused. All the water and sanitary mains were installed by standard trenching with a depth of cover of approximately 1.5 meters and imported bedding and granular backfill were used.

FOR MORE INFORMATION:
Utility contractor: TAG Construction, (604) 534 2685, www.tagconstruction.com
Fusion equipment: Connectra Fusion, (877) 776 7100, www.connectrafusion.com
HDPE pipe supplier: Prolite Systems Inc., (604) 460 8250, www.prolitepiping.com