Scope

QMAX has been looking after a sewer pit in the Greater Sydney area for many years and it has always had crusting issues. This is mainly due to the shallow tank and large diameter giving a lot of surface area for stagnation. In late 2022, QMAX suggested the retirement village to install a sewer mixer to minimise the crust forming and keep the wet well clear of surface and sludge build-up, which was accepted and QMAX started the upgrades. This involved removing the existing lid opening, enlarging the wet well hole and installing a new gas-tight aluminium cover to accommodate the new equipment as well as a new control system to run the mixer on a timer throughout the day. The end result is a system which has experienced many issues over the years due to crusting, now operating seamlessly and efficiently.

Challenges

The major challenge was trying to make room for the mixer to be installed and removed for servicing with a very limited tank opening. QMAX was able to overcome this by removing and enlarging the lid opening and installing a new service-friendly gas-tight lid which allows for the service and removal of both pumps and the mixer on their own guiderail system. We also needed to upgrade the control system to allow the mixer to run periodically though the day and ensure the pit is kept clear of build-up on the surface and on the base. The upgrade needed to take place all in one day, so QMAX was able to work with a vacuum truck company to clean the wet well floor and keep the level down throughout the fit-out.