Full Description

Maintaining the integrity of the distribution system is of utmost importance in protecting public health. However, pressure surges in distribution systems can result in transient periods of low or negative pressures. During these periods contamination of the water supply may potentially occur due to intrusion of outside water into the distribution system. Previous sampling studies have shown that water surrounding distribution pipes can contain a variety of microbiological pathogens, thus suggesting that contamination of drinking water is possible through this route. This paper presents results from the field investigation phase of the American Water Works Association Research Foundation research project on "Field-Testing of Surge Modeling Predictions to Verify Occurrence of Distribution System Intrusion". Pressure monitoring data is presented from various distribution systems showing the occurrence of negative transient pressure events lasting as long as approximately 40-50 seconds (with one possibly as long as 2.75 minutes), and pressures were detected as low as negative 10 psi. Pump failure from power outages was the only known cause of the observed negative pressures. However, the cause of one negative pressure event was not identified but does not appear related to pump operation. Includes 4 references, figures.

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Edition: Vol. - No. Published: 11/01/2002 Number of Pages: 10File Size: 1 file , 300 KB