AWWA WSC70035

This powerpoint presentation begins by providing a brief overview of microbial contamination of distribution systems and pipe surface sampling. Defining the problem included the following: studies in measuring contaminant adhesion and decontamination must reliably load the pipe surface with a known quantity of contaminant, and measure the surface after decontamination to evaluate the effectiveness of the decontamination; method efficiency reflects the combined losses throughout the process of sampling and analysis; and, measure contaminant adhesion and decontamination in pilot scale facility. The experimental approach included the following: Bacillus endospores used as contaminant; evaluated pipe surface sampling techniques included three types of pipe material (PVC, cement-lined, iron) and two sampling techniques (scraping and brushing); and, determined percent adhesion of three types of pipe material (PVC, cement-lined, iron). Test protocols are presented, along with a summary of the mass balance approach, a sample recovery comparison, percent adhesion, and relative proportions of spores collected. Presentation conclusions indicate the following: recommended sampling method derived from this study; no one sampling method is optimal for all pipe surfaces; pipe material and the condition of the surface must be taken into account; and, precision is an important consideration when selecting the sampling technique. Includes tables, figures.