Combined sewer overflows (CSOs) are taking place when the combined sewer network is overloaded. Sewage is then released to the receiving waters at outfalls that are equipped with flapgate that prevents the receiving waters to enter the system. The CSO monitoring is important for municipalities in order to establish priorities and find solution to reduce the frequency and volume of overflows.
This research looks at the efficiency of three methods to determine CSO volume: the flow meter, hydraulic model and Bernoulli equation. The overflow volumes computed from the flow meter are used as the experiment’s reference volumes for comparison with the other two methods. A total of 12 rainfall events were selected during one recreational season. The precision of each event, the global performance and the life cycle costs of each method was analyzed. For the hydraulic model, the average difference for the total overflow volumes is 7.2% with the monitored data. The 95th confidence interval is at 83%. The Bernoulli equation method gives an average difference of 14.7% with a 91% 95th confidence interval.
In conclusion, the method that provides the best results is the use of a hydraulic model. Furthermore, this method has the lowest life cycle cost in the long term and requires less maintenance. With this method, the cities can quantify the overflow volume and respect their CSO limitations engagements, thus helping protecting the receiving waters.
| Date | 9 Jan 2012 |
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| Original language | French |
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| Awarding Institution | - École de technologie supérieure
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| Supervisor | Robert Hausler (Supervisor) |
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Nantel, A. (Author),
Hausler (Supervisor),
9 Jan 2012Student thesis: Master's thesis › Master in Engineering: Engineering