CASE STUDIES
UPAS ST. PIPELINE
World Fair Site Line Replacement
PROJECT SUMMARY
San Diego is one of many American city’s replacing aging infrastructure at the end of its lifecycle. The metal lines providing drinking water to Balboa Park were installed for the World Fair in 1915, and were scheduled for replacement after a century of service.
Fusible PVC® pipe was selected for the line, as a thinner alternative to HDPE pipe (requiring less space to store and assemble onsite). The new line would run beneath Upas St. – a major highway intersecting San Diego’s most important park.
KEY CHALLENGES
Horizontal Directional Drilling (HDD) was deemed to be best construction method due to challenging topography than involved a rising elevation and a constrained work space.
The California Department of Highways (Caltrans) required protective casing for the section of line running under the highway. Once the pilot hole and reaming were completed, The HDD Company pulled the 762 mm (30 in) casing and 609.6 mm (24 in) line simultaneously. The line was ballasted by water to minimize frictional drag as the pipe was pulled.
Construction was planned to allow continued access to a park trail, a school, Boy and Girl Scout facilities and an off ramp. The only closures occurred over a single weekend while pipe was being pulled.