North City Pure Water Pipeline, Subaqueous Pipeline, and AC Water Group 1038
Client: City of San Diego
LOCATION: SAN DIEGO, CA
Project Value: $126M
Project Description: The W.A. Rasic Construction team installed approximately 7.4-miles of 48-inch welded steel pipeline and appurtenances that required six trenchless tunnel crossings along with a new cement mortar masonry de-chlorination facility that included two, 4,000-gallon chemical tanks, feed pumps, analyzers, forced air ventilation, fill and dosing piping, valves, and related elements. The six trenchless crossings required 60-inch diameter casings and varied from 150 to 645 linear feet. For one of the trenchless crossings, the tunnel boring machine (TBM) terminated its path in the Miramar Reservoir (below the lake surface), which required a wet retrieval, using a temporary bulkhead, balloons, and divers to recover the TBM. Eight shafts were constructed using beam and plate shoring at an average depth of 40 feet. The launch into Miramar Reservoir required us to construct a Secant pile shaft to a depth of approximately 100 feet. Rasic also constructed more than one mile of subaqueous HDPE pipeline. The project involved extensive traffic control efforts, in more than 20 distinct phases, and considerable asphalt paving restoration along with replacing curb ramps, sidewalks, curbs, and gutters.