In accordance to best-practice methodology, relevant standards, and/or applicable codes and guidelines, we apply innovative, efficient and accurate analysis of catchment rainfall and runoff to quantify the flood risk of interest areas. Critical flood information, such as peak levels, depths, velocities, hazard, rate-of-rise, time of inundation, damage estimates and scour potential can then be extracted and presented via effective mapping and/or GIS packages. Informed land-use planning and effective flood management can then be produced from this information.  Safety, environmental and development optimisation can also proceed, designing cost-effective mitigation and other structural and non-structural flood strategies to produce the best outcomes for the community.

Flood Impact Assessments (FIA) are typically required for Development Applications (DA) with local and/or state governments in order to demonstrate compliance with applicable flood development codes. Allan & Dennis are DA specialists, we:

• Have a long history with government DA officers and developers alike;
• Clarify jargon that can persist within development codes;
• Identify critical design and approval items relevant to the site;
• Provide pertinent recommendations to ensure a cost-effective and time efficient DA process;
• Cater our approach to a scope appropriate to the DA requirements
• Maximise development amenity, resilience and yield while satisfying risk, safety and drainage constraints;
• Effectively communicate with the design team to optimise integration with other site aspects and provide the best overall product; and
• Provide concise reporting and clear mapping suitable for DA submission.

Stormwater Management Plans (SMP) are typically required for Development Applications (DA) with local and/or state governments in order to demonstrate compliance with applicable stormwater development codes. These codes generally focus on the required Water Quality Objectives (WQOs) and reduction of stormwater runoff pollutants for both construction and operational phases of the project.  Evidence of compliance is generally achieved through the use of pollutant runoff modelling and the design of treatments devices such as bioretention, swales, wetlands and/or proprietary products. Some SMPs are completed as an afterthought, which can result in poor treatment design, unsightly areas and maintenance liabilities. Allan & Dennis have extensive experience in SMPs, from conceptual and detailed design, to overseeing construction, maintenance and handover.  Hence, we know what treatment devices can be practically designed, economically and readily constructed and maintained long-term. This construction and maintenance involvement has feedback into our stormwater design, which has led to much improved development outcomes, amenity and long-term WQO compliance.

Flood affected properties may be developed if a suitable Flood Emergency Management Plan (FEMP) and/or risk assessment is conducted.  Allan & Dennis can develop plans including evacuation procedures, time of closure analysis and the warning systems for effective and proactive flood management. We investigate innovative alternatives to address the flood risk of each specific site, such as:

• Flood Modification – by considering the way in which flood waters propagate through catchments, we design engineering solutions to modify the waterways, such as detention basins, augmentation of existing hydraulic structures, addition of hydraulic control structures, and the redirection of overland flows with levees and channels.
• Property Modification – we look at the way in which people live within floodplains, recommending options to reduce the social and economic impact of flooding. These options generally include the development controls within floodplain areas that either limit types of development, or make specifications on floor planning levels.
• Emergency Response – in the interest of public safety, we consider the way flood waters may affect existing roads and infrastructure within a catchment area, and the duration of flood inundation. This allows both the public and emergency organisations to better adapt and respond during flood events.  These options generally include public education and emergency response planning for relevant organisations.