MEDLI (Model for Effluent Disposal using Land Irrigation) for Sustainable Effluent Management

Relevant Projects:

Effluent Reuse – Council Sewage Treatment Plants:

• Toowoomba Regional Council Clifton STP: supported the design and EA amendment for a new irrigation scheme. MEDLI was used to determine irrigation area requirements and application regimes, informing the design of the Clifton Effluent Disposal Project and supporting a Recycled Water Management Plan and Surface Water Impact Assessment.
• Gladstone Regional Council Calliope STP: conducted an overflow risk assessment by developing a combined GoldSim and MEDLI model to simulate the existing and potential performance of the effluent irrigation system currently supplying the adjacent golf course. The assessment evaluated system reliability, identified potential future land sizing options to reduce overflow risks from the existing dam, and provided cost estimates for the infrastructure required to manage these risks effectively.
• Western Downs Regional Council Wandoan STP: investigated long-term effluent options and compliance challenges to provide potential solutions. The project involved MEDLI modelling to determine land requirements, and explore a range of operational scenarios and plant species nutrient uptake rates to the determine the maximum sustainable irrigation rate and frequency and most efficient crop selection while avoiding effluent runoff and excessive deep drainage. Different scenarios were compared along with the cost estimates to determine the most sustainable effluent reuse strategy.

Effluent Reuse – Mining Sewage Treatment Plants:

• Mine camp STP in Queensland: modelled and quantified the environmental risks associated with nutrient and salt ingress to groundwater and impacts on soil health from effluent irrigation on adjacent cropland, identifying improvement actions.

Effluent Reuse – Leachate Water:

• Composting facilities (long-list of clients and sites): options assessments for composting facilities, identifying strategies to reduce and manage leachate to support environmental amendments and/or in response to environmental regulatory action. This has included developing combined Water Balance Models with Goldsim and MEDLI to evaluate land application capacity for various grass types based on detailed soil characterisation. The assessments addressed environmental risks by minimising surface runoff and deep drainage and verifying long-term nutrient and salt balances through modelling.