REDUCING RISK BY INCORPORATING LESSONS LEARNED INTO THE PLANNING OF THE OUTFALL TIE?INS ON THE EAST SIDE CSO TUNNEL PROJECT IN PORTLAND, OREGON

摘要

Construction on the East Side Combined Sewer Overflow Tunnel Project in Portland, Oregon will span from 2006 through 2011. During this time, a total of thirteen existing outfalls will be intercepted and diverted into the new tunnel. All of the outfall diversion structures are located near the Willamette River at or near the groundwater table. As such, construction must be completed in the “dry” summer months when the river level is down and the chance of rainfall is reduced. Three outfalls have been excavated and tied-in each of the past four summers. This paper will present the unique considerations for each outfall tie-in, the construction methods employed and the lessons learned each summer; showing how risks were reduced during the planning of the later outfall tie-ins.