Banksia – Flood Impact Assessment

Banksia Flood Impact Assessment Map



DPM Consulting Group recently contributed to the development of Banksia in Armstrong Creek, conducting flood impact assessments, and creating a stormwater management plan. Encompassing various aspects of the project, our work ensured the safety and sustainability of the estate.

Review of prior documentation and new regulations

One of the key tasks undertaken by our team was the preparation of a stormwater management strategy for the site. This involved a meticulous review of prior documentation and studies related to the area of interest. We recognised the importance of staying up-to-date with the latest standards and regulations, particularly the Australian Rainfall and Runoff 2019 guidelines.

Hydrological and hydraulic modelling

We took into account factors like updated rainfall intensity, climate change considerations, and pre-burst conditions to ensure the most accurate and reliable data for our stormwater management plan. In order to effectively manage stormwater, we developed a hydrological model using the software RORB. While previous modelling had been conducted for the site, our approach was forward-thinking, integrating the latest standards and data to create a more accurate representation of the site’s hydrology.

Our dedication to precision extended to hydraulic modelling as well. We prepared a preliminary one-dimensional hydraulic model in HEC Ras to simulate the proposed constructed waterway, which would convey flows from the upstream catchment and the proposed development. This model allowed us to visualise how water would flow from west to east within the site, ensuring effective flood mitigation.

Furthermore, we engaged in continuous modelling, evaluating various strategies for volume management. This included designing a temporary retarding basin to attenuate post-developed peak flows and maintain pre-developed conditions. We also considered the increased runoff downstream and the design and construction of infrastructure further downstream to accommodate it.

Design and function in waterway design

Our involvement didn’t stop at technical aspects; we collaborated with landscape architects and other stakeholders to enhance the design of the waterway proposed within the site. This ensured that the waterway not only served its functional purpose but also contributed to public amenity, offering opportunities for community engagement and enhancing the natural features of the site.

Compliance and assessment

Finally, our flood impact assessment was crucial for obtaining statements of compliance for the first seven stages of the project. This assessment demonstrated that flood-prone areas of the site could be safely developed, highlighting our commitment to both safety and regulatory compliance. Utilising TUFLOW HPC, our flood impact assessment provided valuable insights into the estate’s flood risk and mitigation strategies.

Achieving long term success

Our work at Banksia in Armstrong Creek showcased our dedication to comprehensive stormwater management and flood risk assessment. Our use of advanced modelling techniques, adherence to the latest standards, and collaboration with other stakeholders were instrumental in ensuring the success and sustainability of the development.

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