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Maintenance priorities - green or civil

Maintenance priorities - green or civil

The following is the copy from an article that I wrote for the January 2016 edition of the Stormwater Australia Bulletin.

Cheers, Jack Mullaly

I am so passionate about making this water sensitive urban design thing work. Seriously, it’s not funny how much I want this to work.

When I say water sensitive urban design, I mean the big picture dream. The environmental protection. The green leafy streets. The creeks you can play in, with the play equipment right there. The trees in the street for kids and adults alike to climb.

If we’re going to get this to work, we need to cherish that dream and share it widely, but we also need to get the fine details right. Today I’m going to talk fine details. But if you ever want to talk big picture then you know where to find me.

Recently I’ve been chatting with a few people about how to prioritise which stormwater treatment systems to maintain when you’re short on cash and you have many different types of system. Sounds like your local Council right?

In the past I have talked heaps about how to prioritise which bioretention systems to maintain. Simply put, you prioritise keeping the good ones in good condition before you spend money fixing the poor ones. What I haven’t talked about though is how this differs from grey stormwater treatment assets like GPTs, proprietary products, trash racks etc.

At the moment, many Councils have experience maintaining GPTs and are applying that experience to vegetated stormwater assets like bioretention systems and wetlands. That is a great idea. I applaud the Councils who are doing that. Keep up the good work. However, I want to bring a subtle difference to your attention so that we don’t accidentally trip ourselves up along the way.

Imagine a continuum that describes the condition of stormwater treatment assets. It runs:

  • Good condition
  • Routine maintenance required, but if you don’t maintain it, it will still treat the water
  • Routine maintenance required and it’s not treating water any more
  • Rectification required

Imagine a GPT. You construct it. It’s in good condition. It rains and it collects some sediment. You could do some maintenance now and give it a clean but it’s not full yet so there’s no point. It rains some more and at some point it fills up. You don’t notice so you don’t maintain it. That’s fine. It doesn’t collect any more sediment but it doesn’t suffer any damage. Eventually you give it a quick clean and it’s good to go.

Now imagine a bioretention system. You construct it. It’s in good condition. You leave it for a bit. Some weeds start to come in, but it still treats the water perfectly (weeds are plants too right). You leave it a bit longer. There are more weeds but it’s still treating the water. One day you realise that the weeds have taken over. A resident complains and you need to fix it. It’s no longer maintenance. You’re spending capital money on new plants.

There’s the difference. The GPT declines fairly rapidly in condition from good to moderate, but is unlikely to fail outright unless there is a freak event that causes structural damage. The GPT just fills up and starts bypassing. The bioretention system on the other hand shows some resilience early on. It can handle not being maintained for a bit and function 100%, but at some point it hits a threshold and suffers damage that needs a fair bit of money to fix.

Now this isn’t an argument for GPTs over bioretention or vice versa. There are pros and cons for either, but what it does highlight is that when you’re prioritising which assets to spend your money on, you can’t treat GPTs and vegetated assets the same. Imagine you have four assets:

  • 1 good bioretention basin
  • 1 failed bioretention basin
  • 1 good GPT
  • 1 failed GPT

Imagine you only have money to maintain the two good systems, but you receive a public complaint about the failed GPT so you need to spend money on it instead of one of the good assets. Which do you keep funding and which do you stop maintaining?

Take a minute to think about it.

You stop maintaining the good GPT, and keep maintaining the bioretention system. Correct. If you do it this way, the GPT will fill up and stop working, but it won’t suffer any damage. You can just clean it out at some point down the track. You invest a little in the bioretention basin and it rewards you with good performance.

Do it the other way round and the bioretention system stays resilient for a little but might eventually reach a threshold and suffer serious damage. This costs money to fix. You don’t want that.

Keep up the good work. I love hearing about people who are getting out there and making WSUD and stormwater management work. Keep using our experience maintaining GPTs and apply it to vegetated stormwater assets, but remember, there are some subtle differences. Make the adjustments as necessary and everything will work out perfectly. We will be able to have all our stormwater assets functioning properly regardless of whether they are GPTs, bioretention basins, wetlands, street trees or something else.

Did you like this article but wish there were some visuals to go with it? Check out the accompanying video.

The Cost of Our Opinions

The Cost of Our Opinions

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.