Manly Hydraulics Laboratory

NSW Public Works

Manly Hydraulics Laboratory

Sewer Overflow Monitoring

The Environmental Protection Agency is requiring local councils the license all discharges from their sewerage systems and this includes previously uncontrolled overflows during wet weather. MHL was commissioned to record these. The number of sites and councils financial constraints meant that purchasing a conventional flow meter for each site was impossible, MHL conducted some tests on some pipework to see if these could be rated with sufficient accuracy for this project.


The shape of the 150mm pipework was chosen to trap water in the bottom to prevent the escape of noxious gases. The flow was recorded by a pressure transducer in the 'U' pipe and and compared to an electromagnetic flowmeter in the feed pipe.	The pressure to flow rating function had two modes of operation, here is weir behaviour at low flows.


At high flows, (50L/s) a jet mode was present.	Installation of the pipe flow system.


A completed installation with the pipe outlet and data logger enclosure.	At some sites the council had installed overflow outlets, these could be rated with standard calculations.


At some sites just adding a drain was easier.	The drain pipe in place.