Role of the water main in lead service line replacement: A utility case study

The objective of this study was to understand the role of water mains in a lead service line (LSL) replacement program conducted in Halifax, N.S. Water samples from an LSL replacement program were collected from the tap water of 28 homes. In full replacement sites, average lead concentrations in service lines connected to cast-iron water mains with three maintenance conditions pigged, pigged and lined, and not pigged or lined were 31.5 +/- 11.0, 3.3 +/- 2.3, and 3.7 +/- 2.7 mu g/L, respectively, compared with 0.58 +/- 0.2 mu g/L for service lines connected to ductile-iron water mains. In partial replacement sites, average lead concentrations were 63.09 +/- 30.9, 14.60 +/- 2.9, and 6.82 +/- 3.3 mu g/L, respectively, for the three cast-iron main conditions, compared with 8.5 +/- 3.1 mu g/L for ductile-iron mains. Adsorption of lead on iron corrosion scales from tuberculated water mains was suspected for the higher lead release observed.