Robe Community Waste Management Scheme Lagoons Upgrade

Duration: March 2019 – November 2019

Client: District Council of Robe

Location: Robe, South Australia

Project Value: $2 million

Project Description:

As the existing lagoon approached its design life this project required two new lagoons to be constructed to handle the rapidly expanding population of Robe during the tourist season. Given the space constraints of the Council owned land, the new lagoons were required to be overlaid on the existing lagoon. The following components were required for these works;

  • Decommissioning the existing effluent lagoon, creating a temporary bypass into the adjacent storage lagoon

  • Desludging the floor of the existing lagoon and stockpiling the material under EPA guidelines

  • Earthworks to reshape the existing lagoon to form two lagoons, approx. 6,000m3 to build the centre bank

  • Installation of the poly liner and fit out of the new lagoons, including state of the art floating aerators

Challenges:

Given the project had to be completed outside of the tourist season there were strict deadlines on program. This was also a unique project as there has not been many WWTP’s decommissioned in SA. In particular, handling of the sludge and the effective removal of the material was complicated and required several methodologies before an efficient process was found. Various trials were undertaken which included re wetting and pumping the material, injecting a polymer product into the pump cycle to coagulate and separate the water, leaving only bio-solids in specially woven bags for future removal. In the end, allowing it to dry out enough to become spade-able and cart to a nearby stockpile area was the optimal solution, due to both time and space constraints.

Final Outcome:

The project was completed on time and within budget, with additional scope added to facilitate the transition to convert the commercial buildings across to the scheme. A temporary irrigation system was also incorporated to handle outflows until the treatment plant operates at full capacity.