North Harbor Drive Gravity Sewer Project

Southwest San Diego is growing fast, and the rapid expansion threatened the region’s aging gravity sewer system, which had reached its full capacity. Stoppages and spills would be inevitable without action. The EPA, having found hazardous materials there, issued a Consent Decree for system upgrades—with a strict deadline to enforce it.

Residents can now relax, thanks to an upgraded system and expanded capacity. Harris helped meet the EPA’s deadline with the North Harbor Drive gravity sewer project.

Harris & Associates provided construction management services on this complex project, which included:

• Soil management and sampling
• Sewage by-passing, cleaning and televising
• De-watering to deal with soil variations and tide fluctuations
• Schedule management, despite delays caused by the discovery of an existing underground storm drain box, electrical conduits and water main
• Extensive traffic control

Core Elements

The $8.8 million project upgraded an old 39-inch pipeline to 48 inches and increased flow capacity to 25 million gallons per day. Harris managed numerous methods of construction to build the pipeline system, including:

• Open trench construction
• Horizontal directional drilling
• Jack and bore
• More than 1,5000 lineal feet of 48-inch pipe rehabilitation, using cured-in-place pipe (CIPP)
• Installing a 300 lineal foot double siphon using 30-inch HDPE pipe

In addition, two 66-inch steel jack and bore casing sections were installed, reducing construction conflicts below high-power conduits and railway right-of-ways.

Beyond the Blueprints

Soil monitoring was essential to success. There were EPA-designated hazardous materials from a nearby fuel farm and archeological, paleontological and Native American concerns, too—all of which required monitoring. Harris routinely collected and tested soil samples, with more than 100 hauls of soil exported from the site.

Traffic was equally tricky. The project’s location was in one of the city’s busiest industrial areas, home to the main port facility, a Naval station and fuel farm terminals. To accommodate human and vehicular traffic—which often included wide-load transports carrying wind-generator blades—Harris directed traffic with two shifts a day, seven days a week.

The result: The project completed on time, within budget and with client acclaim.