AWWA ACE63095

The 37th Street Water Treatment Plant is one of two water treatment plants owned and operated by the City of Norfolk, Virginia. It was constructed originally in 1920, and serves the citizens in the western half of the city, as well as U.S. Naval Station Norfolk. The treatment plant is served by two 36-inch raw water mains, each approximately 16 to 20 miles long. These mains originate from the City of Norfolk's Western Branch Pumping Station, located in Suffolk, Virginia, and traverse through the cities of Chesapeake, Portsmouth, and into Norfolk. One main, installed originally in the 1920s, includes some of the original reinforced concrete bar-cylinder pipe with lead joints. The other main was installed originally in 1943, and contains large portions of 1940s vintage reinforced concrete (steel) cylinder pipe. Both of these mains have undergone varying degrees of upgrades and repairs during the past 30 to 40 years, including several emergency repairs in recent years. Based on the age(s) of these mains, fear of other future catastrophic failures, and because the two mains are the only sources of water supply to the 37th Street plant, the City of Norfolk determined it was necessary to conduct a condition assessment of the two pipelines. Since these water mains are located in several cities, and lie within limited right-of-way/ easement corridors, it was more prudent and cost effective to conduct a condition assessment of the mains up front, rather than opt for wholesale replacement. The condition assessment helped determine the structural integrity, pressure capacities, and overall condition of the existing water mains, as well as the capability to rehabilitate and/or need to replace these pipelines. It included analysis of the existing conditions of the raw water mains, evaluation of the frequencies of repairs and causes of failure, as well as thorough investigation and inspection of representative segments of each pipeline. This paper presents the components involved in the condition assessment program, including: records research and compilation of data; site selection for field investigations; coordination with neighboring jurisdictions; evaluation and prioritization of pipeline deficiencies; public outreach; and, recommendations for rehabilitation or replacement of the water mains, plus a few of the repair projects currently under design. It summarizes the existing conditions of pipe joints, associated appurtenances, aerial crossings, special structures and other facilities along each pipeline, along with environmental conditions and other factors that will impact the usefulness of these water mains. In addition, the paper describes the development of a data/document management file system utilizing digital aerial photography, which was used to organize existing as-built record drawings, property and deed information, and other important documents, into a single environment. Includes table, figures.