Great Western Highway, Lithgow – May 2016

Lithgow Council recently installed a Sewer Rising Main which empties into a discharge maintenance shaft on a busy highway. A small diameter vent shaft running off the shaft was located on the footpath of a residential area. Due to local design restrictions Council weren’t permitted to install a vent shaft taller than 4m (instead of, for example, 18m x 300mmDN) with an e-duct cowl.

Not surprisingly, local residents began to complain once the works was commissioned and commence operation. As the vent shaft was not tall enough, the odour from the manhole was travelling straight into front yards of the local residents.

The solution, collect data and information in the form of an odour log testing for Hydrogen Sulphide (H2S). Lithgow Council collated an odour log of the discharge from the manhole in question together with nearby manholes. The results of the gas testing was negligible as minimal H2S gases were found.

SVSR then made the decision to block the line of the vent shaft, to then ascertain whether the problem and odour complaints ceased, no further complaints, issue solved.

If the odour complaints continued, then an odour filter would need to be installed on the vent shaft. The cartridge in the odour filter soaks up the odour using activated carbon.

To further investigate the source of the leak a smoke machine can be placed down the manhole or even at the Sewer Pump Station (SPS) and then watch as to where the smoke appears.