Blackwater Pump-Out and Approval Considerations

In this article published by the Marina Industries Association's 'Waterline' magazine, Jeremy Visser discusses some of the key considerations when discharging blackwater.

The operation of recreational and commercial vessels naturally generates sewage. While discharge of sewage/blackwater from any one vessel may not materially affect the environment, the discharge from multiple vessels has the potential to cause significant impacts to water quality and marine life.

This is of particular concern in areas where natural or built conditions prevent the regular flushing of water to disperse sewage. Blackwater is high in nutrients and can cause algal blooms and subsequent depletion of dissolved oxygen in the water. Additionally, blackwater carries a range of health risks (e.g. E. coli) which can make waters unsuitable for swimming and other recreational activities.

The two key options to prevent these impacts are:

  • Discharging blackwater offshore
  • Discharging blackwater to an onshore treatment system.

Under MARPOL (International Convention for the Prevention of Pollution from Ships), at sea discharges can generally only occur when beyond 3nm from nearest land (although in practice, the definition of ‘nearest land’ can push this discharge area much further offshore). While this may be practical for some boat operators, providing for blackwater discharge onshore presents the preferred alternative for many recreational boaters.

Blackwater pump-out at a marina effectively involves the pump-out of sewage from vessels, either into a holding tank for subsequent disposal, or into a system that connects directly into the municipal sewerage system. Depending on your location, the local council or port/harbour authority may already provide blackwater pump-out. However, across much of Australia, marinas provide the main opportunity for pump-out services. This not only prevents blackwater being intentionally discharged to the marine environment, it also reduces the risk of accidental discharges, in the event that a berthed vessel sinks or has a collision.

Blackwater pump-out directly to the sewerage system cannot be undertaken without a trade waste approval (or equivalent). Depending on your State, these may set strict limits on volumes and quality of discharges or may allow unlimited discharges, subject to an initial assessment on blackwater quality. Trade waste approvals can be obtained from your local wastewater utility provider, usually a government owned utilities corporation or a specialist branch of local council.

While trade waste approvals are typically straightforward applications, in some areas utility providers have been hesitant to connect marinas to sewerage systems. This has been due fear that the seawater within vessel blackwater will exacerbate rusting of sewerage infrastructure. While the risk of this is low, you need to be aware of your providers risk appetite and may need to investigate options to reduce salinity concentrations (e.g. mixing with rainwater collected on site).

The alternative to trade waste approvals is to dispose of blackwater as a regulated waste. This can be done through licenced environmental services providers. While typically more expensive, this removes the need to obtain connections to the existing sewerage system.

Different options will work for different marinas, depending on a range of factors, such as location, utility provider and demands of your customers. At the end of the day, the key is to come up with a solution that prevents the concentration of blackwater in your marina and surrounding area.

This article features in the current issue of Waterline (p.27), a quarterly magazine by the Marina Industries Association (MIA). Read the full publication here.


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