Water hammer issues in major horticultural developments.

Hello and welcome to Controlling Water, a space for us to talk valves, water meters, and interesting insights about the water industry. Each episode, we’re joined in conversation by industry professionals that specialise in all things valves, meters, and best practice knowledge in the water industry. We are here with Colin Kirkland, from BERMAD Australia, who is one of the engineers and air valve product managers in Australia.

With more than 30 years experience in the industry, Colin joins us today to talk about water hammer prevention in irrigation schemes. Previously, we’ve discussed methods of controlling water hammer. In this episode, we are going to talk about water hammer issues that occur in major horticultural developments that use water for irrigation purposes. Welcome back, Colin. It’s always great to have you here.

Thank you. Good to be here.

So let’s dive right in. Are you able to explain what sort of horticultural farms and crops we are talking about where these issues of water hammer may occur?

Sure. At Bermad, we have had many many years experience working in irrigation, in horticulture and in agriculture in Australia. And today we work with many of the very large corporate farms where they’re anywhere from 500 to 3000 hectares in size where they’re producing a whole variety of crops. It can be vines, olives, almonds and citrus.

And in Australia, of course, the water cost here is very substantial. And for a lot of these growers who are growing a lot of these crops, water security and the ability to provide this water for irrigation is critical for the farms to work. So we have a lot of experience where, in many instances, we have a lot of farms that are not necessarily located near their water supplies.

So for example, we have many rivers where a lot of growers will take their water source from, but their farms could be kilometers away from there. So there’s a lot of instances in these very large farms where they will take bulk amounts of water, transfer them through these major pipelines and put them to on farm storage, so that might be 2, 3, 4 kilometers away.

And the infrastructure we’re talking about is as big as what we see in water supply or in mining, it’s substantial and it’s reliability is everything because if we are irrigating these crops and we don’t have water, the crops are going to die. So security and the importance of getting water hammer right, especially in the country away from the big cities, where we’ve got lightning, minimal power or power problems in the grid, et cetera, it’s really important that we get it right, and we engineer these solutions well on these very big farms.

Absolutely. Colin you’ve mentioned in previous episodes that the reasons for water hammer is generally due to rapid change in water flow within a pipeline, and I’d encourage our listeners to jump into prior episodes and have a listen of those topics. Are there specific applications on these farms that generate this rapid change?

Yes. The applications of where we use these in irrigation, or very specifically for irrigation, are when we have a farm located some distance away from the water source. So, as I explained before, we have a very large pipeline transferring water at very high rates to the dams. Now we may have one or two days worth of irrigation water on the dam. So this transfer water pipeline and network is critical that it works well. If we have power outages and we have failures of pipelines there, that can be catastrophic, and we are talking about pipe sizes, 600 millimeters, 900 millimeters and bigger. So we’re talking about major infrastructure running over very undulating country with very varying water quality conditions coming from the river.

So the principles are somewhat the same. Yes, we go to the pump stations and we make sure we put in surge mitigating devices, et cetera, and stuff like that on there as well. So it’s really important that we follow the same principles that we’re doing for irrigation here as we do in every other application. One of the key problems a lot of these growers are having is that in the country typically they’re using electric power for a lot of the transfer of the water. And usually when the temperature is very high and lots of people are pumping, there’s a lot of stress on the electricity grid, and they have lots of problems where they have power outages, because they may have lightning strikes or the system could be overwhelmed, and we have dropouts all of the time.

Being able to put in really good solutions like surge anticipating valves, anti-slam air valves and a multitude of other types of products into these transfer schemes is really critical that we do this and we do it well. And the principles, as we’ve said in previous episodes, like getting good surge reports and getting good information and coming up with a good design is really appropriate.

The key thing is that when we’re working in irrigation, we’re dealing with different water quality conditions, and we need to make sure that although these products are all hydraulic and they work without power, they need to work if the water is good or bad, because that’s gonna vary through the year, depending on the river flows, et cetera.

Very true. Very true. Once the water is at the on farm dam storage, and the irrigation pumps are supplying the irrigation applications, are there other locations that allow for the prevention and mitigation of water hammer?

Yes, definitely. What most of the farms are doing once they’ve got the bulk water storage on farm, is they’re basically taking that water and they’re pumping it through usually a large filtration system. Because what they want to do is basically filter out a lot of the solids in the water so they can go into drip irrigation or micro sprinkler irrigation, or possibly into pivot irrigation schemes that are going to water the crops. So there are many things that are very specific that are going to generate rapid changes of flow, which generate that water hammer.

And one of the key locations for this water hammer sometimes comes at the pump station there and also at the filtration station. Because we’re talking about huge banks of media filters, disc filters or screen filters, and these usually all have a form of automatic cleaning or automatic back washing because there are usually very few people on these farms to do the work manually, everything is usually automated. So there’s lots of processes that go on on these farms that generate rapid changes in flow. So if the filters block, they are going to back wash and we get a quick change in flow in that situation, we’re seeing pressure spikes, and we’re seeing pumps ramping up and down. So there are several locations on these farms where this happens.

The other key area, which is quite problematic is, and this is where Bermad’s experience in irrigation really comes to the front. Is that, in a lot of these farms, the farm is usually broken down into smaller segmented blocks because it’s not practical to irrigate 500 or 3000 hectares at once. So they’ll take smaller blocks and they’ll incrementally water individual blocks for certain periods of time.

And each one of these blocks will have its own automated control valve, which will open and close depending through telemetry and through irrigation controllers. So constantly in this scheme that’s going through all of this filtration and then it’s going out into these blocks, the flows are changing all of the time because block one and two are gonna switch off, and the next blocks are gonna come on. So we’re gonna see a spike in flow, followed by a dropoff. And there’s many things that go on at once. It can be quite exciting when you’re there and you’re looking at these big schemes and you’re watching gauges doing some unusual things.

You know, the key things that’s so important for the growers though, is to ensure that infrastructure is safe and Bermad’s experience really comes to the front when we can really ensure that the scheduling for these change of shifts, when these blocks change from block A to B, we know how to make the valves work at a controlled rate with different dwells and to make sure that the filters work at the same time.

There’s years of experience, which Bermad has in irrigation here, which are very very specific in water hammer mitigation. So it could be as simple as, we want to ensure that every one of the block valves that opens, opens over 40 seconds and the other valves that shut, shut quickly, but we can get them to open slowly; so we don’t have too much flow going out in one case.

The problem is that when we have irregular flows in the pipelines, after we’ve filtered that water, if we get excessively high flows, we can get a lot of biofilms coming off the inside of the pipe, which might then block the drippers or the sprinklers, et cetera. So there’s lots of very specific things that are unique to irrigation that we’ve got a lot of good experience in really working with growers, designers and irrigation companies to ensure we keep the process and the water hammer to an absolute minimum.

Now it might include things like surge anticipating valves. It could be we’re using surge prevention air valves to ensure that we fill up sections of the pipe at a slow controlled rate. We basically like to do everything softly if that makes sense. The more we switch things on and off too fast and generate surges, we stress the whole network.

The importance for these growers is that they’re planting crops, which are really designed for the long term. You might be planting almonds that are going to be hopefully there for 20-30 years. You can go to olive groves in Europe and around Australia that have been there for decades. So you don’t want to be digging up the infrastructure after all the root zones have been generated by the plants and everything else, you want the infrastructure on the ground to be there long term. The importance is getting really good information from engineers to really understand what’s good, what’s effective and not always the cheapest, but the best for the farm long term, and that’s what we do pretty well at Bermad.

Let’s take a short break. If you have any questions that you would like answered during this podcast, feel free to get in touch with us through our website, https://www.bermad.com.au or send us an email at info.au@bermad.com, and Colin will be sure to answer them.

Now back to the show. Colin, it sounds like these techniques that you mention are quite specialised and specific in relation to water protection, and this requires really a vast amount of irrigation and hydraulic experience to achieve that desired result. Are the challenges of determining the best result compounded by the fact that you are using irrigation water as opposed to clean drinking water.

Yes, definitely. If I were to look at a lot of the locations where people take water source from, because our valves are hydraulic, it means that they are designed to operate with filtered acceptable water qualities that enable the pilots, the solenoids, and the other components to work reliably without too much regular maintenance.

Now, if you look at a lot of the channels that supply a lot of the rivers, et cetera, you’ll find at different times of the year, the level of suspended solids or the level of colloidal clay or solids in the water can vary enormously. And that has a huge impact on the product that we put in. And sometimes the suggestions that we have is that we may require different levels of filtration or different levels of specifications of products that are best suited to that.

So in many instances, not only are they using river water or dam water, but now in the days of recycling, we are using so much recycled effluent in irrigation for irrigating purposes, because we know it’s full of nutrients and it’s very good and it reduces the use of fertilizers and is great for growing crops.

But the net effect is that those water sources, unless you’ve had experience really understanding what they really mean to reliable products in the field, and you could be talking about a farm that has 2-300 of these valves over many kilometers. And it’s a lot of maintenance, so if they’re not properly configured and correctly filtered and the water is done and that’s taken into consideration, it can certainly have an effect on the amount of maintenance or the effectiveness of the irrigation. So again, Bermad’s experience is something that really comes to the forefront here in giving good advice on what to do.

Love that, always useful. This has been super insightful Colin. Thank you again for the chat.

It’s a pleasure. Thank you.

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