The Lower Molonglo Water Quality Control Centre (LMWQCC) is the main treatment facility for Canberra and is the largest inland treatment facility in Australia.
Sewage is treated and released into the Molonglo River. It then flows into the Murrumbidgee River and drains into the Murray- Darling Basin river system, ultimately discharging into the ocean south of Adelaide. Icon Water’s treatment process ensures that the water that is discharged into the Molonglo River has minimal impact on the environment and downstream users.
To improve plant performance, Icon Water Lower Molonglo Water Quality Control Centre (LMWQCC) replaced an isolation gate. The single isolation gate manages flows across two grit removal tanks, located inside their Raw Wastewater Channel. The arrangement was upgraded to include two new penstocks with built-in stoplogs. Six stopboards were also installed to increase plant process reliability, reducing operational disruptions and maintenance.
Operators require the ability to isolate and control flow into grit removal tanks. Installation of actuated penstocks at the entrance to each of the two grit removal tanks facilitates the ability to isolate penstocks without manual handling. Penstocks also allow partial closure of one or both gate structures to manage flow rates through one or both grit removal tanks.
AWMA custom designed and manufactured a pair of penstocks, one between the diversion gate and each of the two grit tanks. Each penstock was supplied with a stop-board frame and stop-board to facilitate double isolation to each of the grit tanks. This provides improved isolation of the grit tanks during maintenance activities, thereby reducing the likelihood of a significant safety incident. It is anticipated that SCADA connection will provide remote actuation of the penstocks.
The inclusion of six aluminium stopboards, provides secondary isolation between the Primary Distribution Channel and the flocculation/Grit Tanks.
Specifications included the ability to clean the penstock guides without the need to enter the channel or any confined space. Location of the penstock actuation was required to be above the water level to facilitate future maintenance. No moving parts fixed to permanent elements were to be located below ground level. Adhering to the strictly limited and scheduled planned operational shutdown periods and managing exclusion zones, under confined space conditions, were the challenges of this project that AWMA successfully resolved.
Upon final inspection of the infrastructure AWMA was commended on the manufacturing processes; ‘AWMA’s welding in aluminium and stainless steel was exceptional and the best ever seen’.