Using Design-Build Procurement for a Deep Water Marine Outfall Pipeline

King County Washington Wastewater Treatment Division (WTD) is building a new wastewater treatment plant (36 MGD average wet weather flow, membrane bioreactor or MBR) to serve the northeast portion of its service territory around the Seattle, Washington metropolitan area. The project includes an associated 13 mile long conveyance system (four tunnel segments) that will discharge effluent to Puget Sound, a marine estuary in western Washington. The discharge for the conveyance system is a 5,435 foot long marine outfall placed from shore out to –600 feet of water. This paper will cover the use of design-build as a procurement method for the marine outfall including: (1) Advantages of using design-build versus design-bid-build. (2) Design-build procurement precautions. (3) Pre-design studies. (4) Permit procurement process. (5) Request for Qualifications / Request for Proposal Development. (6) Evaluation of proposals. (7) Geotechnical risk sharing. (8) Material price escalation risk sharing. (9) Negotiation of terms and conditions. (10) Partnering. The project was a success for the WTD and the design-build team. It was finished 22 months ahead of the required date for 8 million dollars (20%) less than engineer's estimate. The project won 10 regional, national and international peer awards including Engineering News Record's Best of the Best Projects for 2009 in the Heavy Civil/Public Works category.