The San Antonio Water System (SAWS) is considering using raw and desalinated brackish groundwater from the Wilcox Aquifer to supplement their current supplies. Introduction of a new water source into SAWS’ distribution system has the potential to generate changes related to corrosion, metal release, and aesthetics (i.e., color). Pipes within the distribution system have developed corrosion scales that are in equilibrium with the current water quality. Adding a new water source could disturb the scales, causing a release of corrosion products into the distribution system. This investigation assessed the potential for iron release from corrosion scales inside aged galvanized iron pipe when exposed to various blends of desalinated brackish groundwater and raw brackish groundwater. All of the pipes used in this study were collected from residences in the Alamo Heights area in north-central San Antonio. The results from the three rounds of pipe loop sampling indicated untreated blends of water had significantly higher release rates than treated water at the same blends. Also, at raw water blends of 20% or greater, iron release rates were high, and the Larson Index was a good indicator of the potential for corrosion release. At the water quality tested for this pipe loop study, a treated blend of water that contains no more than 10% raw water is recommended in order to minimize the corrosion release rates within the SAWS distribution system.
This presentation is available to AMTA Members only.
- Mark Graves, PE
- HDR Engineering, Inc.
- AMTA Annual Meeting, San Diego, CA
- San Diego Biennial
- Corrosion, Brackish Groundwater, Blending