AWWA ACE63021

AWWA ACE63021 Morphological, Mineralogical, and Chemical Characterization of Three Iron Tubercles from an Iron Pipe
Conference Proceeding by American Water Works Association, 06/01/2006

Gerke, Tammie L.; Lytle, Darren A.; Schock, Michael R.; DeSantis, Michael K.; Maynard, J. Barry

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Water utilities adjust water quality treatment procedures to minimize corrosion and toremain in compliance with local, state, and federal regulations. Some treatmentchanges though can adversely affect tubercle stability and cause red water and/or otherrelated problems. Therefore, it is important for water quality managers and engineers tohave a conceptual model in place to reasonably predict how such changes will impactthe distribution system. Models require a comprehensive understanding of therelationships between corrosion of the iron pipe and the effects of the composition of thebulk waters on scale development and scale stability. Studies evaluating theseparameters are based on the assumption that one or two tubercle types arerepresentative of tuberculation in the given distribution system. This assumption thoughhas been based on a limited number of real observations and needs to be furthertested, so modeling predictions can be viewed with a high level of confidence.Therefore, the main objectives of this study were to perform a comprehensiveassessment of the physio-chemical properties of three iron tubercles from a single pipeand assess their extent of variability. These results could be utilized to refine samplingstrategies for assessing the effects of treatment changes on a distribution systemswater quality.One 0.11 m long iron pipe segment was obtained from Utility X. Threetubercles were removed from the pipe and allowed to air dry for 72 hours to threemonths. No visable obvious alteration occurred to the samples during drying. Thesamples were then encased in Buehler Epo Thin Low Viscosity Epoxy and then cut inhalf parallel to the length of the pipe with a band saw. One half of each sample waspolished with fine grit sand paper and flushed with distilled deionized water. Subsampleswere collected and ground with a mortar and pestle until they passed through a200 mesh sieve. Includes 25 references.