The Trouble With Conflicting Land Use

Australia's population increased 6% between the 2001 and 2006 Census, according to the Australian Bureau of Statistics. This growth carries numerous implications, some readily apparent and much talked about – such as traffic congestion – and others, equally important, though less visible to the general public.

As populations increase, cities and towns must accommodate the growth with additional residential development, which often leads to construction adjacent to rural and industrial areas on city outskirts. Urban encroachment upon these "remote" locations, which often include wastewater treatment facilities, poses possible consequences for both sides: potentially odorous emissions impacting the new residents and, on the other hand, potential litigation and costly upgrades for the facility owners.

Admittedly, residents do not want to wake up, throw open their windows on a warm summer's day and smell offensive odours; but common sense might seem that appropriate land use planning could enable smart development of land areas around existing plants that have been in place for dozens of years, if not decades. Surprisingly, that is not always the case.

In New South Wales, Section 129 of the Protection of the Environment Operations Act 1997 makes it an offence for offensive odours to be emitted from premises. While there is guidance available for determining the need for odour emission control at facilities, once the new residences are in place, there is no allowance for who settled first and residents have the right to request clean and odour-free air at the expense of the plant operators. This means that developers of new residential areas can buy less expensive land close to a facility and then insist that facility operators comply with odour impact limits. As Sydney, for example, continues to stretch beyond its existing north-western and south-western boundaries, this will become a more pressing issue for wastewater utilities and other odour emitting facilities in these types of areas. Similarly, this is an issue for other growing cities as well.

Industry, public utilities, their consultants and advisers deal with these issues every day. Sometimes the solution involves negotiation with regulators and developers. Sometimes the solution requires employing cost-effective odour control measures within the sewage transport and treatment processes. And other times, the solution involves employing odour capture and control systems. Often, it is a combination of all three options.

For a recent project in New South Wales, MWH used dosing of the incoming sewage to reduce the odour load released at the treatment plant, combined with a biofilter odour control system to capture and remove residual odours before discharging the treated air into the atmosphere. For this location, neighbours were located close to and overlooking the facility, yet, as one recent visitor to the facility said, "you can't smell the treatment plant at all".

Not all situations are suitable for biofilters, however, and other technologies such as chemical scrubbers need to be used. MWH has developed and implemented a new chemical scrubbing process that reduces chemical consumption, energy consumption and greenhouse gas emissions while delivering guaranteed odour emission levels.

Where odour control measures need to be implemented to minimise the impacts on new neighbours, whole-of-life costs are critical for the odour control measures. While "costs" used to just be about dollars, the community now expects public utilities to look at "climate change" and "greenhouse gas" costs as well. By incorporating these factors in the life cycle assessment, benefits for the facility owner, the local residents and the broader community can be achieved.

Innovative thinking and clever design can result in affordable and successful odour treatment and containment solutions, creating a win-win situation for plant owners and their neighbours.

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