How to design an Australian stormwater treatment solution with BMPs in mind

A specialist partner can help engineers and designers to combine the right stormwater treatment solution with the right best practices. 

Designing stormwater solutions for industrial sites - such as mines, food processing facilities and manufacturing plants - that are focused around best management practices (BMPs) is a significant challenge in Australia. While the US and UK both have extensive and well-crafted legislation relating to industrial stormwater runoff, in Australia the regulations are often either over-prescriptive or vague.

Inexplicit regulation in the industrial sector opens the opportunity to engineer a wide variety of solutions, but this in itself can cause problems. Though engineers in these circumstances have more power and discretion than in (for example) the UK or USA, knowing where to start becomes problematic. This is often because of a general lack of awareness about the breadth and varying quality of the range of available solutions for different types of industrial sites.

One size doesn’t always fit all

Engineers may be naturally inclined to take a cautious “rubber stamp, black box” approach for sites where they are designing solutions. If an approach has been approved and has worked well on one site, there is a tendency to apply it across all others. However, for the industrial sector in particular, this type of approach is not necessarily appropriate or viable.

Off-the-shelf designs may not necessarily work, or may not provide and leverage the best mix of solutions for a particular site - in these cases they will inevitably fail to deliver the best possible value for money.

Adopting best management practices

It’s vitally important to challenge the precautionary “one size fits all” mindset, and to enable engineers to confidently consider BMPs as an important option for stormwater management. These innovative solutions allow pollutants to be filtered out or controlled at source, and can provide a cost-effective and environmentally friendly option.

The aim of these systems is to ensure that pollutants such as total suspended solids (TSS, or sediment), nutrients, oils, heavy metals and other environmentally damaging materials are removed from storwmater runoff and captured before they reach a body of water such as a river, lake or ocean. An effective treatment system combined with a flow control device can ensure that water flows into a drainage network and ultimately infiltrates naturally into the environment at a rate similar to that found when rain falls on natural, absorbent surfaces - minimising flood peaks and ensuring that pollutants are retained and properly treated.

Choosing the right solutions

Engineers need to consider solutions that combine the simplicity of BMPs with sophisticated, smart engineering. This will allow them to to ensure treatment for a range of coarse, fine, and dissolved pollutants, even during high flows. With few or no moving parts, these systems are ideally suited to tackle the challenges of pollution carried both in regular rainfall and by Australia’s cyclical flooding.

Existing examples of solutions provided in different areas include those chosen for the Tuloma river in Russia, which was suffering from coal dust pollution carried by stormwater runoff from local mines. The pollution was damaging important Atlantic salmon spawning grounds and therefore reducing coal dust levels was seen as a priority.

After laboratory testing of the local influent, an advanced stormwater treatment solution was proposed that comprised a chemically-dosed Downstream Defender® hydrodynamic separator and an Up-Flo® Filter advanced filtration system. A pilot trial proved that the system captured over 95% of the coal dust in the surface water runoff, and the concept was approved for a full-scale deployment.

These and other technologies can be integrated into BMPs as key parts of an overall solution alongside other low-impact elements such as swales, detention ponds, permeable paving and modular storage. Together, they enable managed infiltration of stormwater back into the environment.

Working with BMP and solution experts

Engineers should work with a partner whose experts work collaboratively with you to determine the best way in which environmentally-friendly, cost-effective solutions can be leveraged to suit the needs and restrictions of a particular site.

The aim should always be to ensure that an optimum solution is reached that benefits businesses, local residents, other stakeholders and the wider environment, as well as fulfilling the requirements of all applicable legislation.

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