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Horizontal directional drilling and fusible pipe provide a new discharge system while minimizing impact on a busy campus. The new system was not only less intrusive but more cost-effective in the long run.

The Scripps Institution of Oceanography at the University of California - San Diego has maintained a seawater system to support its research and teaching mission since 1910. The system currently draws 1 MGD of seawater from an intake pipe at the end of Scripps Pier. After filtration, the seawater is stored in holding tanks until used in experiments or aquarium life-support systems. Until recently, the water would then be commingled with stormwater before it was discharged back into the Pacific Ocean. State regulators began issuing discharge permit requirements for the institution's effluent in 1969. The permit was reissued in 1979, 1984, 1994 and 1999. Meanwhile, the State Water Resources Board designated the waters off the institute's coastline - the San Diego Marine Life Refuge - as an Area of Special Biological Significance, specifically ASBS 31.

Although the California Ocean Plan prohibits waste discharges into ASBSs, the State Water Board adopted a resolution that grants the institution an exception if it complies with all of its National Pollutant Discharge Elimination System (NPDES) permit requirements. The goal was to ensure that the seawater system's effluent would not alter ASBS 31's natural water quality. Separating seawater and stormwater flows was deemed essential, but reconfiguring the 80-year-old system was an arduous engineering task. Also, proposed modifications to the open-flow system had to be carefully evaluated to ensure that they would not jeopardize the marine life used in research and public exhibits.

Evaluation of possible solutions

The institution had six months to submit a report to the regional board. The report included an evaluation of the costs and feasibility of potential solutions, as well as partial or complete diversion of flows to the municipal sewer system, alternate treatment techniques, and pollutant minimization and source control.

The project team considered four alternatives:

* Separating the seawater and stormwater discharge systems,

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