Sludge Under Pressure

by Carl Sepponen, (M.ASCE), Sr. Engr.; Nolte & Associates, San Diego, CA,
F. Stuart Seymour, (M.ASCE), Project Manager; San Diego Clean Water Program, San Diego, CA,

Serial Information: Civil Engineering—ASCE, 1993, Vol. 63, Issue 1, Pg. 72-74

Document Type: Feature article


Few wastewater engineers ever have to deal with high-pressure pumping. In San Diego, however, city engineers will soon oversee a 100,000 ft long psi main that will transport sewage sludge to a new processing site. San Diego, like many U.S. cities, is faced with an increase in sludge as a result of population growth and higher solids-removal rates. The city's existing sludge processing facility (located 7 mi from the treatment plant) and the 8 in. diameter pipeline that fed it were inadequate. To solve the problem, a $200 million processing facility located 19 mi away is scheduled to open in late 1997. A single 1,500 gpm pump station serviced by a 12 in. diameter, 570 psi sludge force main, made from polyethlene-lined ductile iron pipe will deliver the sludge to the out-of-the-way location. From the beginning, the most logical route for the pipeline presented many problems for the design team. After crossing a military base, the alignment runs through a public park and an affluent neighborhood. The pipeline designers also had to contend with the impacts of construction on heavily traveled business corridors, an earthquake fault, internal and external pipeline corrosion, and a requirement that the pipeline run at least 5 ft away from existing utilities.

Subject Headings: Sludge | Pipelines | Pumping stations | Pipeline design | Pipe sizes | Wastewater management | Utilities

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