AWWA WQTC62372

This paper discusses the planning, implementation and results of Washington Aqueduct's Pipe Loop Study that is designed to complement the ongoing lead research work being performed by the District of Columbia Water and Sewer Authority (WASA), the US Environmental Protection Agency (USEPA), and associated members of the Technical Expert Working Group. The primary purpose of the proposed flow-through, lead pipe loop testing is to evaluate the effectiveness of alternate corrosion control strategies on reducing lead concentrations in District of Columbia drinking water. Secondarily, the results obtained during the testing period will be disseminated to the water industry at large as a good will offering. Based on the results and recommendations of Washington Aqueduct's 2004 Desktop Evaluation, a comparison of the effectiveness of two alternate corrosion inhibitors (phosphoric acid and zinc orthophosphate) will be conducted. Filtered and finished water produced at Washington Aqueduct's Dalecarlia treatment plant is used as source water for the testing. Additional treatment chemicals are added to the filtered water flow stream to "simulate" finished water quality under a variety of conditions. Samples of lead service lines excavated from the Washington D.C. water distribution system were used to construct the pipe loops to ensure that the test results replicate actual full-scale conditions to the greatest degree possible. Includes 2 references.