External drainage solutions that protect building infrastructure from floods and storms

According to the Melbourne Climate Change Adaptation Strategy, significant changes in water systems are expected to result from climate change. Section 6 outlines that “the potential for storm drain inundation and flash flooding will likely increase with more intense rainfall events accompanied by sea level rise.”

Australians don’t take flooding or drought lightly, and with good reason. Not only does severe weather in Australia significantly impact upon our newsfeeds and TV bulletins, it can also impact on essential infrastructure like roads, rail, and communications, cause property damage and injury; and loss of productivity.

Exemplary of this was the damaging effects of floodwaters entering Brisbane’s CBD riverfront skyscrapers in 2011, where structural integrity was compromised and access cut off to offices, basements and power supplies. This event caused 23 tragic cases of drowning and 18,000 properties were damaged in metropolitan Brisbane. This is a prime example of how severe weather conditions can have a flow on effect, not just for businesses and transportation systems, but for public health and safety.

Poor water management: ramifications

Ponding or flooding is evidence of poor surface water management and/or excessive water runoff. This affects urban areas where sufficient drainage products aren’t put in place. This can compromise the integrity of our infrastructure and is associated with severe health risks and infections; contaminated water with sewage and debris; seeping oils and pollutant soil damage; waterborne diseases, electrical risks, and disruption to the communication, transportation and health care industries.

Poor water management can damage buildings and their contents, disrupt transport systems, interrupt business operations and result in lawsuits associated with injuries to individuals and communities. It can even severely impact upon those not in the immediate vicinity; interruptions can affect the flow of interconnecting railways and roads, as well as economic productivity, capacity and function. In other words, a business might not suffer the brunt of the consequences, but access to essential goods and services may be compromised.

On a less devastating scale, we are increasingly witnessing the ramifications of climate change. In fact, the Australian Rainfall & Runoff is a published set of guidelines for designers and planners dealing with water management across a wide range of projects. To take into account more relevant data due to climate change and other new methods of analyses, in 2016, the guideline was updated for the first time in nearly 30 years.

In Australia, our cities’ are particularly sensitive to storm water control against the backdrop of rapid urbanisation and the desire to preserve essential infrastructure and heritage buildings. Upgrading our drainage infrastructure must be integral to all planning. Intelligent drainage systems need to be integrated into urban designs to provide a robust defensive strategy to protect against water runoff.

The ACO solution: protecting people from water, and water from people

ACO Polycrete is an Australian company that designs and manufactures drainage products to ensure the longevity, serviceability and safety of the built environment.

ACO is a world leader in trench drainage and provides project specific design services to designers in a number of areas including hydraulics. Known within the industry for its competency in technical support, the company has had an ongoing involvement with the University of NSW (UNSW) in research and testing, specifically in the area of grate hydraulics.

Trench drain systems are used for surface water management to keep pedestrian and vehicular pavements safe and serviceable.  KlassikDrain, SlabDrain and PowerDrain systems are all grated modular trench drainage systems belonging to the ACO Drain Range. All systems have built-in falls making them easy to integrate into any project.

Properly located trench runs put grates in the direct path of surface water runoff but a grate has a finite capacity to capture flow (lateral inflow). Bypass occurs when this exceeds the grate’s hydraulic capacity.

The science of grate hydraulics is extremely difficult to model in fluid mechanics. This is because every unique situation is greatly influenced by subtle changes to either or both the grate and ground surface geometry. This can result in a variation of flow scenarios at the grate inlets, laminar or non-laminar, viscous or non-viscous, and rotational or irrotational, to name a few. Fluid flow can get very complex when it becomes turbulent.

As it is impossible to employ a theoretical approach to this science to achieve meaningful results, ACO have opted for full scale experimental research. Three reports (February 1998, April 2004 and September 2016) prepared by the Water Research Laboratory (UNSW) focus on the capture rates for a number of ACO grates recorded at various water flows discharging down a ramp at a set of longitudinal angles and some cross falls. The research and testing phase also included the documentation of the behaviour of the fluid entering the grate and the mode of failure (at bypass), giving excellent feedback for further product development.

The ACO difference

With details on the surrounding catchment surface type and geometry (on-grade or sag); rainfall intensity and preferred grate type, ACO can recommend a grate to suit projects’ unique hydraulic requirements. The impact of debris and leaves as well as the catchment surface characteristics can also be taken into account.

Thanks to the partnership spanning almost two decades with the Water Research Laboratory, UNSW and through the relationship with the universities key researcher, Brett Miller – Principle Engineer, ACO can confidently assert that grate capture is no longer just an art form – it is science working at its finest.

ACO also commissioned the Water Research Laboratory to develop an in-house Grate Intake Calculation (GIC) programme to complement its other hydraulic software. This programme is specifically built around the empirical results of its full scale grate testing, which allows ACO’s established Technical Services engineers to give accurate recommendations to engineers and architects with specific project requirements.

ACO’s Technical Services Department has many years’ experience advising on surface drainage. This free service is offered with no obligation and is supported with extensive high quality information, brochures and technical documentation. ACO is committed to, not only providing the best quality products, but also a technical support service that is second to none. This is part of ACOs unique and hands on value-add approach.

To learn more about or to request this service, contact ACO on 1300 765 226 or visit ACO’s technical pages.