Trenchless in San Diego

by William J. Swallow, III, Associate Civil Engineer; San Diego Metropolitan Wastewater Department,

Serial Information: Civil Engineering—ASCE, 1995, Vol. 65, Issue 5, Pg. 78-79

Document Type: Feature article


The Middletown Trunk Sewer is located near downtown San Diego. Sewage backups prompted a study, recommending construction of a larger replacement pipeline. The City of San Diego prepared construction plans and specifications for both open trench and microtunneling options to install the new pipeline. The lowest bid to construct the project was an open trench option, and a microtunneling option was the second lowest bid. The city justified the selection of microtunneling because its social cost (in terms of street disruption and inconvenience to commuters and businesses) was much lower and construction was safer. Construction of the Middletown Trunk Sewer Project behan in February 1993 making it the first microtunneling project in San Diego and the second in California utilizing clay jacking pipe. Construction involved the installation of 460 m of 500 mm diameter direct clay pipe between 12 jacking/receiving pits. During construction a petroleum hydrocarbon plume was mitigated along a portion of the project, and the tunneling machine did get stuck during one drive and had to be removed through open-trench excavation. The pipeline was successfully completed in early 1994.

Subject Headings: Project management | Microtunneling | Construction management | Pipelines | Trenches | Social factors | Sewers | California | United States

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