Outfall Pipeline Lines, Tutuila AS, 2009, US EPA Region 9
Description
The outfalls extend from coastal points, originating from canneries and sewage treatment plants.Tafuna Outfall: This polyethylene pipeline installed in 1996, is 24” in diameter, 1500’ in length and extends from the shoreline to a depth of 95’. The pipeline is anchored along its entire length for protection against frequent hurricanes and the large waves and strong currents that accompany them. The anchoring systems used were a combination of rock bolts and Manta Ray sand embedment anchors. Utulei Outfall: This was a very challenging pipeline design and installation because of the extreme slope that existed along the course of the pipeline. The outfall pipeline is 24” in diameter, 350’ in length, and it begins at the reef edge at a depth of 5’ and plunges to a depth of 165’. The pipeline has a free floating catenary section that spans the steep slope, and it is heavily anchored at the bottom in deep water.