AWWA ACE70834

This powerpoint presentation begins by providing a brief overview of pilot test protocols that included: constructed test loops at 5 sites; loops contained four 6 in. long segments of: 3/4 in. lead pipe, 3/4 in. copper tube with 5 in. long bead of 50/50 lead-tin solder, and 1/4 in. diameter bar of leaded brass in 3/4 in. PVC; water flow was 5 gpm (3.6 fps) in each of 3 parallel legs; fed identical phosphate doses (based on plant PO4 dose) in each leg with high zinc concentration (1:1 or 1:3 ZOP), low zinc concentration (1:10 ZOP), or no zinc (75% PO4); used a 10-hr stagnation period nightly; and, operated each loop for six months. A summary of corrosivity results is provided, along with a summary of water quality results. Study conclusions indicate that: overall, zinc does not appear to have a substantial impact on corrosivity of lead, copper or mild steel; zinc does not appear to play a role in protection of steady-state metal release from piping materials, its role in the release of particulates, especially lead is unclear; and, at locations where differences were statistically significant, no clear pattern emerged - sometimes zinc improved performance, sometimes it hindered performance. Includes tables, figures.