Proceedings of the Pipelines 2011 Conference, held in Seattle, Washington, July 23-27, 2011. Sponsored by the Pipeline Division of ASCE. This collection contains 135 peer-reviewed technical papers that discuss new solutions to some of the most critical infrastructure issues involving pipelines. The U.S. water and wastewater infrastructure systems are continuing to deteriorate. The recent economic downturn has increased the gap between current and required levels of funding. These serious financial constraints highlight the urgent need for creative and innovative solutions to improve our water and wastewater infrastructure systems. From the technical perspective, cost effective materials, proper planning, new design methods, innovative construction technologies, and advanced condition assessment technologies must be more aggressively developed, tested, and introduced to the industry. From the management perspective, optimal use of financial resources, smart and carefully crafted decision making processes on maintenance, rehabilitation and replacement activities must be made available, applied by and used by water and wastewater infrastructure agencies.