PVC Pipe Meets Stringent Rules, Harsh Conditions of Aquariums

SAN DIEGO, Calif., March 7, 2008 (VNS) — PVC piping has long been used in aquariums to ensure the purity of the water circulating through the tanks, and it also proved the best choice for disposing discharge water at the Scripps Institution of Oceanography at the University of California, San Diego.

Anka Fabian, P.E., the university’s principal civil engineer, chronicled the project in the February 2008 issue of Pollution Engineering.  In a recent interview, Fabian explained that Scripps had to change its 80-year-old pipe system because in 2005 the State of California imposed additional requirements, beyond those in Scripps’ National Pollutant Discharge Elimination System permit. (NPDES was created to meet the requirements of the Clean Water Act.)  These extra measures were to ensure that effluent from Scripps’ seawater storage and research tanks would not alter the natural water quality of the biologically significant San Diego Marine Life Refuge off the coastline. Scripps had five years to meet these new requirements—or else the operation would be closed down.

The old pipe, which included concrete sections, had combined stormwater discharge with Scripps’ seawater discharge. The first step was to separate the two streams by laying a new PVC pipe for the high-volume, high-velocity seawater discharge of 1.2 million gallons a day. (Given the climate, there’s little stormwater overflow, Fabian explained, so, for the time being, what little stormwater discharge there is will remain in the original piping.)

 “I love PVC,” Fabian declared.  Seawater is highly corrosive, she explained, but PVC is impervious to it, unlike other materials from concrete to clay to metals.  “It’s durable and very smooth,” she said. “The low friction on the inside surface means there’s less chance of biological growth.” Algae, crabs and mussels tended to live in the old piping, which had to be cleaned out every six months, she said, “but PVC is low maintenance.”

For the new pipe, Scripps chose a patented and trademarked fusible PVC pipe produced by Poway, Calif.-based Underground Solutions. Contractors used a special drill to bore a path for the pipe, and then pulled the pipe through. This trenchless installation method caused minimal disturbance on campus.  Contractors also found the PVC was just flexible enough to allow them to thread the pipe through underground areas that were crowded with utilities. The project, completed last year, used more than 4,000 feet of Underground Solutions’ Fusible PVC™ pipe.

Fabian reported that, thanks largely to the PVC project, the State of California is satisfied with the substantial progress Scripps has made toward meeting the new requirements.