What does MEDLI actually do?

MEDLI is the Model for Effluent Disposal via Land Irrigation


The reiterative simulation process will provide you with a clear set of:

  • Wet Weather Storage capacity (tanks to store your effluent while it’s raining);
  • Irrigation area required, and
  • Irrigation regime (how much effluent and how frequently it can be discharged)

How Does the Modelling Process Work:

When developing a MEDLI model we will take a set of known site data and look at a number of variables to come to the best operational practice (both environmentally & economically).

Typical inputs are:

  • Soil type and quality: either from your site’s soil investigation or from literature;
  • The vegetation over your irrigation areas (grass, native forest etc): either existing or planned;
  • Local climate data (we gather this information on your behalf)
  • Estimated effluent quality & quantity (this comes from your proposed treatment plant design)

The variables are then:

  • Wet Weather Storage capacity;
  • Irrigation area size,
  • Irrigation regime, and sometimes, when the variable are restricted, we would also look at the effluent quality.

So What?

The larger your irrigation area, the more irrigation depth you can apply on any one day, which means you will need less wet weather storage.

If land availability is low and you don’t want to ‘waste’ space for effluent irrigation, you can opt to have a higher level of treatment and a larger wet weather storage volume. This will save you some land area.

The value of being able to predict your operational requirements before the plant is built cannot be underestimated. Changes made at the planning stage will cost way less and are easier to implement than when you’ve already got a plant installed onsite and an EA in your hand!

Why Might You Need MEDLI:

Apart from the new site establishment, you will also likely to need a MEDLI model completed if:

  • A periodic assessment using MEDLI or equivalent is one of your licence conditions;
  • You are planning a site upgrade: increasing you site’s waste flows beyond you current EA threshold;
  • You have struggled to comply with the limits set in your current EA and, as a results, the administering authority ordered you to complete soils assessment and a MEDLI model on the historical effluent quality and quantity to demonstrate the environmental impacts.
  • You are looking to see what more your irrigation area can do to assimilate effluent and what more can it produce (cash for crop).