The Longest Drive—Portland's CSO Microtunnels
Abstract
As part of the City of Portland, Oregon’s East Side Combined Sewer Overflow Tunnel Project, nine separate 2130 mm (84-inch) diameter reinforced concrete pipe microtunnel drives totaling approximately 2380 m (7,808 ft) are being constructed to divert flows from several of the existing outfalls to the main tunnel. The drives were constructed in challenging ground conditions that include soft soils under the groundwater table, large amounts of wood and metal debris, and close proximity to sensitive structures. While all of the drives will be addressed, the focus of the paper will be on the 931 m (3,055 ft) continuous drive connecting Outfall 46, currently the longest microtunnel driven in North America.
2009
Rapid Excavation and Tunneling Conference (RETC) Proceedings
Christa Overby
Bureau of Environmental Services, City of Portland, OR
Matt Roberts
Kiewit-Bilfinger Berger (KBB) J.V.
Craig Kolell
Jacobs Associates
