1. What is the mitigation hierarchy?

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There is a 3-step process to mitigating impacts on ecology, biodiversity, and cultural heritage sites –

Step 1 - AVOID


Step 3 - OFFSET


The key provisions from most modern environmental legislation is sustainable development and the use of the mitigation hierarchy. The Hierarchy states that if a biodiversity value is to be impacted, then you should first attempt to avoid the impact altogether. If that is not possible, then the impact should be minimised (such as reducing the construction footprint or redesigning to make an impact smaller). Finally, if the impact cannot be avoided or minimised then the impact should be mitigated. Mitigation can mean different things and relates to how the impact can be lessened by employing other measures. A good example is the use of rope bridges to allow koalas to cross a new road. Finally, after all that is done, there still may be residual impacts from the development. In these cases, the impact on biodiversity values can be compensated through the use of offsets.

The BAM is also used on other properties to assess potential offset sites to compensate for those impacts, which gives you ‘credits’. By finding the right offset site and generating the right kind of credits, we can compensate for the impacts from the project. There is also a whole range of guidelines and other documents that ecologists follow to detect threatened species and assess the presence of their habitats on both the project site and the offset site.

Watch and take notes on the video below, to gain a better understanding of what exactly these terms mean for an environmental planner.

Consider whether you’ll need to change the alignment to bypass sacred sites or endangered species, and the repercussions of that change: this could include more studies, possible impacts on residents, and land resumptions. 


Alternatively, as we've already heard from our mentor, Vanessa, mitigation strategies could include constructing dedicated culverts, glider poles and barrier poles for impacted fauna, as well as monitoring and reporting requirements. 


Scarred trees can be photographed and catalogued prior to removal in consultation with registered Aboriginal parties, and by a qualified archaeologist, whereas artefact scatters can be salvaged prior to construction.

As a last resort, you’ll want to offset the impacts you can’t avoid. This is where impacts can’t be avoided. Developers might, for example, allocate funds to compensate for impacts on the environment and cultural heritage along the alignment route. This could look something like this:

Check out more about offset management here.