I wrote this article for the August 2015 edition of the Stormwater Australia bulletin.

Cheers, Jack


When the editor of the bulletin approached me to write this piece, my initial reaction was ‘wow that’s a good opportunity, but sorry I can’t. I’m sitting in Brisbane airport and won’t be back in the country for a month’

But then I had two more thoughts. I had an idea for an article that I feel is well and truly worth writing, and I thought of a challenge. Could I write a high quality article on a flight to Singapore before my laptop battery went flat? If you’re reading this then I certainly got the article done. I’ll let you tell me if you think its high quality.

I’m going to share something with you today that I touch on when running Healthy Waterways’ Managing and Maintaining Vegetated Stormwater Assets Course, but which I don’t think that I have talked about in such a public forum before. I’m going to share with you some thoughts on which Council departments are most suited to maintain vegetated stormwater assets, and how this affects perceptions of cost.

Before we get started, I’m going to add a couple of caveats to this.

The first is that this is a rapidly developing field. These are my opinions based on my experiences to date. They are not the definitive truth. Develop your own hypothesis, determine a way to test it, get the testing done and report back. I look forward to seeing your data so I can continue to develop my knowledge on this topic (or any other for that matter).

The second is that in the article I am talking solely about maintenance. To my mind, maintenance is when you take an asset in good condition and do the necessary works to keep it in good condition. It’s different to rectification, whereby you fix a dodgy asset. Rectification is also an important topic, but it’s one for another day.

When we do this in our training course, the first thing that we do is sit down as a group and brainstorm all the sorts of maintenance activities that we might need to undertake in order to keep a vegetated stormwater asset working.

Now that’s a pretty big task. Let’s make it a little easier by focussing on one technology. Let’s go with bioretention systems because they’re so common.

Take a moment and think. What sorts of maintenance activities do you think would need to be undertaken to maintain a bioretention system?

Wait... I know what you just did. You went to skip ahead to the part where I tell you what I think. How do I know that? That’s because that’s what I would have done. However there is value in taking the time to consider the question. So, thirty seconds. Have a think.

Ok. Got a list?

  • Here are some common ones that come up during our training courses:
  • Remove litter
  • Remove sediment
  • Fix scour
  • Manage weeds
  • Replace plants
  • Water
  • Remove debris from inlets and outlets

Did you have anything else to add?

Once we have the list, we consider ‘which activities are most common?’ Another way of looking at that is ‘which activities, if we don’t do them, are most likely to cause the asset to fail?’ At this point, opinions tend to diverge a bit. What do you think the most common activities should be?

Personally I think that managing weeds is most important. Why? Because if you don’t manage weeds, they outcompete the desirable vegetation. The desirable vegetation dies and then you spend lots of money replacing vegetation to fix the system.

Next we consider which departments in Council have the skills to undertake the above tasks. What departments do you know of who might have the skills?

Normally we arrive at three options. The names definitely vary from Council to Council and so do the organisational structures, but normally we arrive at three:

  • Parks (landscaping and horticulture)
  • Natural areas (bushland and other natural spaces)
  • Stormwater drainage (stormwater pits and pipes)

So at this point we have an opinion on what tasks need to be done, which might be most common and what departments might have the necessary skills. The appropriate question is therefore ‘what organisational structure is most suited to doing the maintenance?

We normally settle on a structure where one department owns the assets and has overall responsibility for maintenance. They do most of the regular maintenance as it fits within their core skillset, then contract the remainder out to either other council departments or to an external contractor.

But wait, who should be the lead department?

Opinions vary here. Mine happens to be that it should be natural areas, or someone from parks with a bushland management background. Why? Because I believe that weed control is most important, and that weed control without using herbicides is best. This fits best with the natural areas skill set.

But honestly, my opinion isn’t the most interesting thing about this story. What’s interesting is this! In my opinion, when a stormwater drainage team becomes responsible for maintenance, they tend to estimate maintenance as costing more than a natural areas team. Why does that happen? I think it’s because the different teams have different opinions on the priority of each maintenance activity, and this is turn effects costs.

So what’s the moral of the story?

Well I don’t think that it’s ‘you shouldn’t give maintenance responsibilities to stormwater drainage teams because they think it costs more.’ After all, perhaps they are right about those costs.

No, instead I think the moral is ‘when you are talking to people about maintenance costs, be aware of their background, and how that will affect their estimate of costs’. That includes when you’re talking to me. I’m as susceptible to cognitive biases as anyone else.

Enjoy maintaining your vegetated stormwater assets and I’ll speak to you soon.