MANAGING CHANGE TO AVOID UNINTENDED CONSEQUENCES RELATED TO THE LEAD AND COPPER RULE CORROSION CONTROL PRACTICES

摘要

The Lead and Copper Rule (LCR) requires utilities to maintain optimal corrosion control to prevent the dissolution of lead and copper into drinking water without compromising other health-related water quality goals. Maintaining optimal corrosion control treatment (CCT) has become increasingly difficult as new regulations with competing water quality objectives become effective. As utilities implement changes to meet these new objectives, they are increasingly at risk of jeopardizing compliance with existing requirements and water quality goals, particularly in the areas of CCT and LCR compliance. When making a change in source, treatment, or distribution operations to meet a new water quality objective, it is important to assess the potential impact on corrosion and, when necessary, re-optimize CCT. The water quality factors that most directly impact lead and copper corrosion are pH, alkalinity, and orthophosphate concentration (when a corrosion inhibitor is used). Changes that impact these parameters are most likely to impact lead and copper solubility, and require re-optimization of CCT. However, there are other parameters (e.g., total dissolved solids, chloride-to-sulfate mass ratio, and secondary disinfectant) that can also impact lead and copper corrosion. As such, it is always good practice to assess the potential corrosion impacts of any change and re-establish optimal CCT, if necessary. It is perhaps inevitable that utilities will take all of the necessary precautions prior to implementing a change and still experience negative unintended consequences. In such cases, a review of historical data, expanded baseline monitoring, and other tools are available to help identify the cause of the unintended consequence. It is also good practice to increase monitoring or use other tools, such as harvested pipe loop studies, to monitor the impacts of a change on CCT effectiveness. The State or primacy agency should be contacted prior to implementing any change to confirm utility requirements related to corrosion control and prevent project delays.