We helped Pittsburgh Water and Sewer Authority (PWSA) identify and implement a more effective corrosion control treatment approach to reduce lead levels in drinking water and are overseeing the replacement of more than 4,000 lead service lines per year.
As a result of increasing lead concentrations measured at customers’ taps, PWSA entered a consent order with the Pennsylvania Department of Environmental Protection (DEP) to complete a corrosion control study, prepare a service line inventory and replace lead service lines. Since 2017, we have worked with PWSA to reduce lead concentrations at their customers’ taps and improve water quality throughout the distribution system.
Our approach
A corrosion control study conducted by PWSA identified orthophosphate addition as a more effective corrosion control treatment (CCT) than its prior treatment. We assisted PWSA with the development of strategies to prepare the distribution system for the new CCT approach, including pre-conditioning of large water mains as an alternative to unidirectional flushing and introduction of orthophosphate at multiple facilities in the system to speed scale transition. We provided technical expertise to PWSA during the first 18 months of operation with orthophosphate and lead levels now consistently meet the EPA’s standards for drinking water.
We also serve as the construction manager for the lead service line (LSL) replacement program. In this role, we are responsible for verification of the LSL inventory and replacement of more than 4,000 lead service lines per year. Prior to implementation, we reviewed the proposed program plan to identify needs, gaps, and priorities.
We also conducted a comprehensive review of distribution system operations and water quality data to identify and remedy the cause of low chlorine residuals in the system despite the use of booster chlorination. Process control and automation improvements were recommended to improve chlorine residual maintenance and pH stability throughout the system.
Outcome
Water quality throughout the system has improved. PWSA is in compliance with the Lead and Copper Rule, and their customers are receiving safe drinking water on a consistent basis.