AWWA ACE69102

Although much work has been conducted on the effect of phosphate corrosion inhibitors on lead and copper, surprisingly few studies have been conducted on the role of phosphate inhibitors in protecting concrete or cement-lined pipe as a function of water quality. Likewise, corrosion of concrete and associated lime dissolution might either benefit or hinder a utility's corrosion control strategy. That is, if pH and alkalinity are too low, leaching of lime to water would be beneficial for lead and copper corrosion, but if pH and alkalinity are at their upper range of effectiveness, lime dissolution would be detrimental. This paper provides an overview of AwwaRF 4033, Impact of Phosphate Corrosion Inhibitors on Cement-based Pipes and Linings. The project is divided into three tasks. Task 1 includes gathering data and information from a number of water treatment utilities to examine current practices regarding phosphate and silicate corrosion inhibitors. As part of that evaluation, water quality data, information concerning concrete or cement-lined pipe failures, and compliance with the U.S. Environmental Protection Agency (USEPA) Lead and Copper Rule has been collected. Task 2 utilizes bench-scale testing to provide insight into mechanisms of phosphate and silicate interactions with cement. Task 3 incorporates field sampling of utilities identified in Task 1. Includes tables, figures.