CLIENT: Gold Coast Water
INDUSTRY: Water Utilities
TYPE OF PROJECT: Sewer Treatment Facility
WHEN: August 2020
In September of 2020, Gold Coast Water (a division of the City of Gold Coast) contracted Pipe Management Australia (PMA) to reinstate an overgrown irrigation ditch bioreactor at the Merrimac Wastewater Treatment Plant.
The irrigation ditch had not been used in some time, and was laden with silt, vegetation and some animal life. Gold Coast Water needed to conduct repairs on another asset at the Merrimac Wastewater Treatment Plant. This would require reinstating the irrigation ditch.
PMA was engaged for a three-day period. Their objective: to remove the waste in the ditch and return it to optimal working capacity.
Gold Coast Water selected PMA due to an existing working relationship, well equipped fleet and experienced operational staff.
There were a number of challenges for PMA to overcome as this project was taking place in an active wastewater facility.
Confined space: PMA staff would need to descend into the irrigation ditch, approximately five metres below ground level. There was no real level platform for a tripod or Davit arm to be put in place. PMA would need to come up with a solution for staff to safely clean the ditch.
Heavy vegetation growth: The cells of the irrigation ditch were overgrown with weeds and other vegetation. Recent rainfall had also left a decent amount of water at the bottom of the ditch.
Fauna: Due to the growth of vegetation, a number of small animals and birds had taken up residency within the irrigation ditch. These animals would need to be safely relocated before any work could commence.
To help crew members access the irrigation ditech, PMA utilised a towbar mounted Davit arm and man cage as a secondary solution for confined space entry. The Davit arm was used to enable the access ladder to be set in place on the cell wall which was at a 45-degree angle. All operators were attached to the retrieval winch and a large inertia reel during access and egress of the cell.
To remove the majority of vegetation and waste from the cells PMA utilised a large crane truck with an 8m3 skip. A clamshell bucket attachment was fitted to the long reach crane and used to remove 18m3 of solid vegetation prior to any washdown works. Additionally, PMA had three heavy vac combo units on site to remove liquid waste and wash down the asset.
In cooperation, Gold Coast Water and PMA staff safely relocated wildlife from the work zones.
PMA supplied the latest equipment and an experienced crew. The team showed innovative thinking when tackling tasks that were out of the ordinary from daily works.
PMA removed and disposed of 117m3 of waste at a regulated waste facility. A further 20m3 was disposed of at the council’s main treatment plant at Coombabah.
Although the project was scheduled to take three days, the PMA crew were able to complete the work in two 11 hour shifts. This resulted in considerable savings for the client.
Additionally, because PMA completed the works ahead of time, Gold Coast Water were able to bring the plant online earlier. This was timely as there were issues with another asset that could have shut the plant down resulting in a potentially harmful discharge of sewage.
Ultimately, the work was carried out and completed a full shift prior to client’s expectations. The cells were thoroughly cleaned with all waste removed.