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  • James Howey

Meddling with MEDLI

The QLD Department of Environment and Science (DES) recently provided four days of very much anticipated training on the MEDLI program for modelling effluent disposal to land.

The course was excellent and included presenters such as Ted Gardner, Allison Vieritz, Sunil Tennakoon, Bernie Powell, Weijan Wang, Roger Shaw and Ian Ramsay. The course attendees also were also a great group of experienced water professionals including attendees from NSW, WA and NT, from consulting, soils, contaminated lands and regulation. It was great to see behind the model and get a better understanding of the science of effluent disposal, soils and cropping.

The course was divided into an introductory day, a science fundamentals day and two days of advanced modelling. It is a requirement of environmental approval applications in QLD for STPs that propose to dispose effluent to land, to undertake MEDLI modelling to demonstrate that the impacts to soil, groundwater, vegetation cover and waterways are mitigated and meet environmental objectives.

The model uses climate data, water quality data, soil data and crop characteristics to predict the likelihood of overflows from holding lagoons, the impact of water volumes, salts and nutrients on soil and the optimum irrigation regime to keep the crop alive.

Paired with risk assessment processes, MEDLI modelling provides a good indication of the land area required to dispose of effluent, the volume of the holding pond or lagoon and the shandying required to ensure the sustainability of the activity.

Viridis specialises in risk assessment for the environment and public health and developing our capability in MEDLI Modelling is seen as a way to provide better value to our clients and assist in improving environmental performance, gaining environmental approvals with conditions that reflect the achievable operational environment.

Thank you to the MEDLI team at DES for an excellent course and all of the presenters who gave their time.

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