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Project Overview

For there to be a risk associated with ingress there are three requirements

Contaminants

There must firstly be a source of contaminants in the local surroundings of the pipe.
Research studies [1,2] have shown, by taking samples of the ground water from the vicinity of leaks and during pipe repairs, that many biological and chemical contaminants are present.


Pathways

There must exist a pathway for the contaminant to get from the ground water into the pipe itself.  The are many different types of pathway that might exist, leaks, badly joined pipes, malfunctioning air valves etc.

Pipe Leak

Driving Force

Typically even though there may exists a contaminant and a potential pathway for into the potable water supply, the internal pressure means there s no possibility of ingress occurring.  It is only with an additional driving force to overcome the pressure gradient that ingress can occur.  One possible driving force is the creation of pressure transients in the pipe.  These short term fluctuations in the pressure are due to dynamic hydraulic conditions (changing of flow conditions) such as to valves opening and closing or power outages stopping pumps. 


Transient Schematic

Research Approach

We undertook a series of ambitious experimental studies, in a purpose built facility, to directly measure ingress volumes due to a broad range of transients and realistic ground water conditions. Alongside this a progam of of computer modelling was undertaken. The invesitgatory program utilised hydraulic pipe modeling and detailed ground water flow modeling. Hydraulic modeling was undertaken using the Aquis Water Network software produced by 7T, together with new ingress models produced through the project derived from Computational Fluid Dynamics (CFD) simulations. 

< 1,2 >

1.Karim, M, M. Abbaszadegan, and M.W. LeChevallier. Potential for pathogen intrusion during pressure transients,  JAWWA, 2001
2.LeChevallier,M. Gullick,R. Karim,M. The Potential for Health Risks from Intrusion of Contaminants into the Distribution System from Pressure Transients, USGov white Paper, 2002
 


 
Maintained and updated by Richard Collins, July 2009