Protecting Anchorage’s Costal Wildlife Refuge by Sliplining 16,000 feet of Sanitary Sewer Force Main

摘要

The Anchorage Water and Wastewater Utility provides water and sewer service to the Anchorage Bowl which is one of three service regions within the Municipality of Anchorage (MOA). The Anchorage Bowl is further subdivided into five municipal planning areas. The southeast region including the Hillside District which is also commonly known as South Anchorage and/or Anchorage Hillside. The AWWU sewer infrastructure is configured to collect sewage from South Anchorage at Pump Station 31 (PS31), pump the sewage to Pump Station 30 (PS30) and pumped again to the gravity system in DeArmoun Road.PS31 and PS30 and the associated force mains (FMs) between PS31 and PS30 are reaching the end of its useful life. In addition to the aging infrastructure no sewage is collected at PS30 other than that pumped from PS31. There are no defined plans to expand the AWWU sewer infrastructure to collect sewage from South Anchorage to PS30. AWWU has also experienced sanitary sewer overflows and complaints from the public of undesirable odors emitted to the neighborhoods at and adjacent to the Alaska Costal Wildlife Refuge including Potter’s Marsh.Therefore, AWWU has elected to upgrade PS31, mothball PS30, and rehabilitate the force mains (FMs) from PS31 to PS30. The project presented significant challenges associated with the mitigation of construction impacts to the Coastal Wildlife Refuge, Potter’s Marsh and a State-owned roadway, the Old Seward Highway. Other significant challenges included redesigning infrastructure originally intended to function as a system by removing pumping equipment within PS30. This paper discusses how AWWU overcame those challenges through the design and construction of the Pump Station 31 and Pump Station 31 Rehabilitation Project.