Project Overview
The City of San Diego needed to replace a region of sewer infrastructure in the Pacific Beach and Mission Bay areas. A total of 3,700-lf. was identified for pilot tube guided boring trenchless installation to minimize tourist traffic disruption. This area is home to many beaches, aquatic sports and the Sea World theme park, so continuous highway traffic was a challenge.
The project included the replacement of existing sewer mains applying the following construction methods:
• Rehabilitate approximately 3,700-lf. using pilot tube guided boring trenchless technology
• 4-21-ft. depths through the median of the main arterial 4-lane roadway and neighborhood
• Replace-in-place and realign approximately 11,645-lf. within existing trench alignments via open trenching
The work also included replacement of 50 existing manholes, pedestrian curb ramps, new sewer laterals, and re-plumbing of existing sewer laterals.
The project was initially bid as open-cut construction. In the first 700-lf., the soils were so unstable that trench widths reached 15-ft. The soil was also contaminated which required a significant amount of disposal. As costs and social impacts mounted, the owner re-bid the project with the pilot tube guided boring trenchless solution encouraged wherever possible.
