Boral has sought to avoid and minimise impacts to indigenous flora and fauna have as much as reasonably practicable; however, due to the nature of the site and extractive industry, the complete avoidance of native vegetation is not feasible.

Notwithstanding that, Boral has adopted an iterative design approach to the expansion to reduce the disturbance footprint and avoid significant environmental impacts. 

An independent biodiversity impact assessment was undertaken for the proposed expansion of the Montrose quarry. It identified the extent and type of vegetation present within the proposed disturbance footprint.

Biodiversity field assessments were undertaken to identify and characterise the flora and fauna values within the study area. The area was also visually assessed with active searching under and around ground debris for reptiles, frogs and small mammals was undertaken. The site was scanned for birds, nests, droppings and footprints. Potential habitat for fauna was assessed, with an emphasis on habitats that may provide shelter, food or other resources for significant species.

A total of 28.471 hectares of native vegetation was identified in the entire study area, with 323 large trees within or close to the proposed disturbance area. Of this, the project will result in the direct removal 8.779 ha of native vegetation including 262 large trees recorded within the patches of native vegetation.

The native vegetation impacted by the project is shown in Figure 1, and is based on the proposed extraction limit boundary extension area and the outer edge of the tree canopy that just falls outside this boundary

Of the vegetation to be removed, the Herb-rich Foothill Forest (EVC23) (listed as ‘least concern’ in the Highlands – Southern Fall bioregion) will be impacted.

Three State-significant flora species were observed within the proposed extraction boundary during the initial biodiversity assessment and will be affected by the project:

• one specimen of the Sticky Wattle (vulnerable)
• two specimens of Dandenong Wattle (endangered)
• 105 Mountain Bird-orchid plants (vulnerable).

It is not considered likely that the impacts to threatened flora would result in the potential loss of a significant portion of habitat or population.

Targeted surveys were undertaken for the following nationally significant species: 

• White Star-bush
• Gang-gang Cockatoo
• Southern Greater Glider

The nationally significant Gang-gang Cockatoo has the potential to forage opportunistically within the site and wider locality and are not expected to rely on vegetation present within the site for their needs. The targeted Gang-gang Cockatoo surveys recorded 60 trees within the proposed extraction boundary proposed for removal that are potentially suitable for nesting purposes.

The State-significant Powerful Owl has previously been recorded in the site, although was not found during field assessments undertaken for this project. There are 26 hollows that could be potentially suitable habitat for the Powerful Owl within the proposed extraction boundary proposed for removal.

Based on the findings of the biodiversity assessment, Boral refined the pit design to reduce the amount of native vegetation removal as far as reasonably practicable while still making the project viable. 

The projects footprint will result in forest loss that contains large trees with a variety of hollow sizes which are likely habitat for important fauna such as the Gang-gang Cockatoo, Southern Greater Glider, Powerful Owl, Barking Owl and Sooty Owl.

Boral has sought to minimise impacts to native vegetation as much as reasonably practicable with the proposed extraction area initially 10.798 hectares reduced to 8.779 hectares in this application. Additional measures to reduce impacts on biodiversity include engineering solutions to reduce run-off, waste water treatment, and rehabilitation works within the buffer areas and post extractive industry activities.

Given there is approximately 48 ha of mature forest outside of the project footprint within and directly adjoining the site, the loss of 8.779 ha within the project footprint is not considered to represent a large loss of critical habitat, comparatively. Furthermore, as the Dandenong Ranges National Park is situated approximately 1 km east of the site, there is considered ample contiguous mature forest in close proximity which could provide habitat for protected fauna.

The project is therefore unlikely to result in the potential loss of a genetically important or significant species, or the potential loss of critical habitat for significant species.

The potential for indirect native vegetation loss as a result of changes to the groundwater and surface water environment along Bungalook Creek have also been assessed as part of the project.  The Groundwater Dependent Ecosystem Assessment identified a further five ecological vegetation class’s (EVCs) present along Bungalook Creek. The potential for indirect impacts to these EVCs associated with the predicted groundwater drawdown and potential changes to Bungalook Creek streamflows were also assessed. The assessment of groundwater reliance of these species determined that the vegetation is not accessing groundwater and are preferentially utilising the higher nutrient soil moisture that is recharged by rainfall. The risk of indirect loss of EVCs along Bungalook Creek is therefore considered low.

The State-significant Dandenong Burrowing crayfish have previously been identified in Bungalook Creek. Potential changes to the streamflows of Bungalook Creek associated with the quarry extension may affect their habitat. The risk to burrowing crayfish may increase as quarry operations proceed, then decrease during decommissioning and manifest during dry periods when Bungalook Creek flows are low. Crayfish burrows will continue to benefit from being wetted by surface water runoff. Crayfish are also known to be extremely adaptive and mobile and are likely to adopt survival strategies such as relocating their burrows, reducing surface activity and sealing of burrows to maintain moisture.

To mitigate this potential impact on Burrowing crayfish, Boral is proposing to return the volume of groundwater captured at the quarry to Bungalook Creek to maintain the streamflow of Bungalook Creek and reduce potential impacts on burrowing crayfish, assuming they are present. With this mitigation and ongoing monitoring of the creek, the residual impact on the species is considered medium.