As mentioned in our Friday news story about the $150 million NRRRP (Northern Rivers Recovery and Resilience Program), the Lismore LGA has about $29.4 million to spend on seven projects, two of which have been completed.The two completed projects are the revitalisation of the South and East Lismore town drains, which allows for a clearer path for stormwater to reach the Wilsons River, and clearing community drains.That leaves five more projects for Lismore, into which we will gain detailed insight through Garon Clough, Lismore City Council's Project Director—Flood Resilience Program.Garon began by stating what the purpose of the NRRRP is for Lismore."It's addressing reliability and operational resilience to make sure that the infrastructure functions as best as it can during an event, and it brings the majority of the levy systems, all of its components, up to the same level of design, because some of the aspects of the levy system predated the 2002 installation and needed to be brought up to capacity."There were also some identified local catchments that weren't addressed from a stormwater management perspective in the initial design, and those deficiencies within the levee system are being addressed under this program.""One of the projects under the program is improving the control and the visibility of the sites. That's been done by connecting all the major sites with a fibre optic cable, which enables remote control, additional instrumentation, CCTV monitoring. Far more functionality than currently exists in the infrastructure.Previously, there was a manual component to some sites, and the visibility of each site was non-existent."When water starts to overtop a levee at that location, there's not that trigger immediately on the site we're relying on, I guess, gauges, which will improve the level of service after this. "Garon explained that each flood overtops the Lismore levee at different points because of varying hydraulic grades."There are different points of the levee system that could overtop in different events. There is an engineered spillway at Browns Creek, and that's the primary overtopping side for the levee or for the CBD side. There's another engineered overflow at Gas Works Creek, which is further downstream, but most floods would overtop at Browns Creek first on the CBD side. The South Lismore side is really flood-dependent. So it depends on whether it's a Lycester Creek dominated flow or a Wilson's River dominated flow.The total investment to upgrade Lismore's pumps and pump stations is $22.5 million. A significant sum of money because of age.BROWNS CREEK PUMP STATIONBrowns Creek Pump Station was constructed in the early 1970s, and the levee wall was constructed in 2005. Browns Creek Pump Station was not upgraded at that time."We've looked at the capacity of Browns Creek and the flow that we need to put through that pump station to install the infrastructure to enable that. It's not going to fit in the existing structure."So, at this point, the project will need to be a pump station constructed in parallel to that site. But there is still value in that building and the gate and some of that infrastructure, because it does house real estate above our design level, so it will be incorporated into the design, but the pumps won't be housed in that building anymore.For those worried about a potential flood while the new Browns Creek building is being constructed, Garon and his team have worked through the issue."The design approach is to maximise the amount of time that Browns Creek remains operational, including the flood and the pumps during construction, to make sure that Lismore isn't put at risk during the construction of that major project.""We currently have two pumps, and we're anticipating putting in a four-pump configuration. The multi-pump configuration gives a wider range of potential flow rates, so we can handle different local storm events. The order of magnitude is four to five times the current pumping capacity of that station."The pump's primary function is up until the levee overtopping. So they're managing stormwater behind the levee so that people can evacuate, and we're not getting premature flooding behind the levee prior to it overtopping. We're pumping from the Browns Creek catchment, so around the Square, areas where you'll first see that water starting to back up, we're pumping that into the river.Do the pumps help clear the water once the levee subsides?"They will help, but the volume of water that overtops the levee, the pumps make a marginal difference to the point of, it's not really measurable. The height behind the levee system after a flood will essentially be the same height in the river. So it's controlled by how quickly the river drops. So, having pumps running after an event doesn't really get people back to clean up afterwards.The pump's main objective is to keep evacuation routes open as long as possible and to limit stormwater damage during an event where all the floodgates are shut. It's not letting stormwater back up.As you would expect, the four pumps will be submersible and need to be ordered from overseas."In modern pumps, submersible is a better configuration, a more resilient configuration than the current axial drive pumps that are there. The pumps have been selected, and we're just going through market assessment at the moment. They haven't been ordered."Major construction for that project is 2026; it was always planned for that stage. There's been a lot of work to go into Browns Creek in understanding and trying to maximise the benefit from this upgrade. If we could have tried to stay within the bounds of the existing building, we wouldn't have got the benefits realisation. We've grown that project to get the most benefit from this pump upgrade.Garon explained the work that has happened and will happen at Browns Creek to assess the best outcome for the community."There's been a number of site works, geotechnical investigations, drilling, a 3D scan of the existing structure so that we can design the new structure in 3D. The pumps will be ordered, and they'll be in manufacture. Then there'll be early works, such as probably realignment of that levee to give us enough construction room and digging the well. Those are the activities that will happen first, before the pumps get installed.GAS WORKS, CBD AND SOUTH LISMORE PUMP STATIONSWhile Browns Creek is bespoke proprietary equipment, the other pump stations are on a much smaller scale, and manage a smaller catchment."Those pump stations, I guess, are not as large and can be delivered a little quicker. They're all moving into the construction phase. So, the investigation has been completed. We're just going through the procurement of pumps and contractors at the moment.The Gas Works pumps will be the same; they'll just be modified. They were sized correctly in the initial build because that pump station was constructed as part of the levee system. So they'll be maintained."Hollingsworth and CBD are a quarter of the size of a pump at Browns Creek. So, the type of pump is slightly different just due to the capacity."Construction will start on those in 2025 and continue throughout the rest of the year."Once Garon gets his contractors on board, he will be able to give a completion date for the smaller pump stations more accurately.During the 2022 March Flood, many people in the CBD would notice the tractor pump at work. That will be a thing of the past."That will be a new, modern pump station with submersible pumps and electric drive. So, that pump station will essentially be remote controlled like everything else. It won't need that operator intervention to be physically on site, running that pump station, which is safer for the operator.""The advantage of having a modern pump station is that you can adjust operation levels. You can change the flow rate during an event to manage it and reflect the stormwater that you're seeing."One issue that Garon and his team have is testing the pumps once they are installed. You have to have a lot of water to achieve this because they are designed to pump high volumes of water. That is something that is being discussed at the moment.The other challenge is stopping debris from entering the pumps or creating an impediment that will lower the flow of water."That's the design challenge with installing them. But Debris Management for these pump stations is really important. Pump stations that don't currently have screens will be getting screens at the pump stations themselves."The main trash racks are being designed in a way that's both operationally friendly but very conscious of not creating any localised storm water issues."It is a challenge to install that infrastructure in an area that has a ground level of six metres, and we need to protect all the infrastructure.WIDENING BROWNS CREEKAll the Lismore projects are around managing stormwater during an event where the levee system is within its design capacity. Lismore City Council will be managing stormwater by keeping roads open longer, making sure the pumps operate where they're not going to be impacted by debris, and if we do get a large event similar to 2022, the infrastructure is not going to be damaged like it was previously.In terms of widening Browns Creek along Brewster Street, we all know that it quickly inundates with stormwater during heavy, continuous rainfall, cutting off the road prematurely."We're going to try and increase the capacity and reduce the frequency of that occurring," Garon said.NOT MITIGATIONThe NRRRP has nothing to do with flood mitigation. It is all about making Lismore more flood resilient."It's protecting properties from stormwater inundation. So when the floodgates get shut and the river rises, the capacity of your stormwater is reduced because now it's got to be pumped uphill. It's no longer flowing under gravity. So we've got to manage stormwater as best we can in an event where the floodgates are closed."So, it's stopping property damage, keeping evacuation routes open, and then also doing it in a reliable way that it's going to stay operational for an extended duration of time."Flood mitigation for Lismore sits under the Flood Risk Management Plan, and they're always looking at mitigation options for Lismore. This program is targeted at bringing up the entirety of the levee system and fixing gaps within that, to bring it up to a functioning level system."If the levee is raised or something occurs into the future, all these upgrades would have had to be done anyway. So it is improving the function of the levee system. It's about providing resilience to the existing levee system where it operates."