By: Melissa Moody
Replacing more than 3 miles of badly deteriorated sewer lines beneath the streets of Los Angeles is no easy task. Particularly with high potential for ground contamination, adverse impact to surrounding neighborhoods and a web of underground utilities and oil lines in the area.
Originally bid for open-cut installation, contractors decided the optimal method to replace the sewer lines was to dig 14-ft below city streets to pipe burst decades-old vitrified clay pipe (VCP) and upsize sewer lines to high-density polyethylene (HDPE).
“This was the largest pipe-bursting project completed in Los Angeles to date,” said John Chammas, with ISCO Industries. “Using the trenchless pipe-bursting method we were able to replace the gravity sewer lines and upsize the existing lines with minimal excavation.”
Minimal excavation meant minimal disruption to city streets, traffic flow and surrounding businesses, including the industrial Port of Los Angeles area. The likely possibility of unforeseen conditions—the underground sewer lines were installed more than 50 years ago—would have created financial burdens and traffic delays.
ISCO Industries supplied project subcontractor Mocon Corp. with 8-in., 12-in. and 16-in. HDPE pipe to increase the sewer lines by two sizes—from 8-in. VCP to 12-in. HDPE and 12-in. VCP to 16-in. HDPE. The Los Angeles Bureau of Sanitation supported the use of pipe bursting because that method typically utilizes HDPE fused as a continuous piece of pipe—providing better protection from root damage and potential groundwater inflow and infiltration.
In addition to financial, contamination and traffic considerations, keeping the project on budget was another reason the city chose pipe bursting.
“This type of project was a first for the city,” said Robert Morrow, president of Mocon. “It took the cooperation of many people.”
