AWWA WQTC64083

This study focuses on the capability of corrosion inhibitors to mitigate the adverse effects of changing water quality in distribution systems that receive blended finished waters that are produced from ground, surface and saline sources. The inhibitors used are Orthophosphate (OP), Blended ortho and polyphosphate (BOP), Zinc Orthophosphate (ZOP) and Silicate (Si). Data is collected from a large field facility, which includes 14 pilot distribution systems (PDS), 14 copper Corrosion Loops that contain one each Pb/Sn coupon, 14 Cradles that contain metal coupons that are used for chemical and biofilm study and were taken from the pipes used to construct the PDSs, and finally 14 Nadles that are used to collect EN data from Fe, Cu and Pb/Sn electrodes. The PDSs, Corrosion Loops, Cradles and Nadles are paired such that each paired group receives the same water quality. Preliminary metal release models using EN parameters are presented. The study began in February 2006 and data through June 2006 is discussed. Corrosion monitoring is conducted by Linear Polarization, Electrochemical Impedance Spectroscopy and Electrochemical Noise techniques. The current data indicates that iron release correlates with general corrosion while copper and lead release correlates localized corrosion (pitting). Particulate release is correlated with pitting and uniform corrosion. Includes 4 references, tables, figures, appendix.