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Flood Team Saves Significant Cost To Developers In Major Subdivision Project

Located close to Boondall Wetlands, our recent subdivision project for Heran Building Group was always going to present challenges when managing flood and stormwater, but through a combined approach involving our flood and civil team we saved the project over $750,000.

The project involved the creation of 82 lots at Stanworth Rd, a site that immediately raised a number of red flags when considering appropriately developing the site.

Inertia’s Senior Civil Engineer Nathan Green outlined the potential challenges, “To start with we were dealing with a greenfield site that was triggering 700,000 litres of onsite detention. The lawful point of discharge was through a Queensland Rail corridor, which required a non-worsening solution, and the area was prone to flooding due to inadequate existing stormwater provision which meant that in times of flood, the system backed up.”

But through an integrated approach and the collective talents of our civil and flood teams, we were able to design a solution that met the needs of all stakeholders, providing a more efficient drainage solution that enabled runoff to escape directly into the wetlands.

“The traditional approach in a situation like this would be to look at the runoff and simply factor in a detention tank to store and slow-release the water into the stormwater system. Typically, on a site like this that could cost around $750,000, a significant figure for any development.”

“Through the use of state of the art modelling, we were able to clearly map the site, where water would flow and fully analyse several scenarios that we could work through with the client. And thanks to our combined flood and civil experience we could ensure that each solution was thoroughly analysed and costed from a schedule, cost and risk perspective which meant that what we proposed could be immediately factored into the developer’s budget.”

The solution was to improve the efficiency of the existing local stormwater infrastructure, which negated the need for costly detention tanks and met the criteria of the client, Queensland Rail and Brisbane City Council.

“Our modelling showed that we could deliver a non-worsening solution for Queensland Rail through making improvements to local stormwater systems, at no cost to council or ratepayers. Flood design should be based on efficiency and practicality. On this site, we were able to make simple improvements to infrastructure that resulted in the more efficient run off of water into the neighbouring wetlands.”

Despite all of their work and diligence, approval for the development to the desired configuration and design was not guaranteed.

“You can never guarantee success with a DA. But we felt that this project had a great chance of being approved because of the combined approach we took across flood and civil engineering and the fact that we had undertaken significant work to ensure that the application was based on evidence and solid engineering.”

“We are delighted to say that we received approval for the development with no RFIs from the council. On such a complex site, this is a huge achievement and saved significant time, resources and costs in the development process. To receive a DA in such a way is testament to the hard work that our team undertakes when working on a complex project.”