FLOODING MANAGEMENT UPDATE
21 October, 2022
As many of you would be aware, the major flooding of the North Esk River on Thursday 13 and Friday 14 October led to a breach of the levy bank at Scotch Oakburn Park (SOP) in the early hours of Friday 14 October. The College has progressed a crisis management response to the flooding event, with the recovery process ongoing.
I note the following high-level comments in relation to the event and the recovery process, noting the early stage of the process and lack of clarity at this point regarding the playing surfaces restoration plan (due to the majority of the playing surfaces still being underwater, and the emergence of a significant silt layer on areas partly exposed):
- College preparations for the flood event were well coordinated, particularly when compared to the last major flood event at the Park in 2016. Significant notice/forecasting was provided prior to the event, which enabled the majority of vehicles, plant and equipment to be relocated prior to the event;
- The level of the flood at SOP was very similar to 2016. Whilst the river height at Corra Linn, the closest upstream guide on the North Esk River, peaked at 6.3m (compared to 6.5m in 2016) – the levels reached at the Park as measured by building markers were almost exactly as per 2016. A ‘major’ flood level for North Esk at Corra Linn is 4.9m. The levy banks at SOP were designed to withstand an estimated 1 in 100-year flood event. Unfortunately, we have had two of those events in the past six years;
- At the peak of the flood, the whole precinct, including access bridges, roads, and buildings (to a level of around 1.5m) were inundated;
- Within the first couple of days, the water had receded to form a lake within the levy bank system of the Park (approximately 7 hectares) over the playing fields, with the bridges/roads/buildings accessible;
- A preliminary engineering assessment was carried out on the pedestrian and vehicle bridges that access the Park on Monday 17 October, which indicated the structures are sound;
- The College released a large outlet pipe that drains water from the lowest point of the playing surfaces back to the river, on Monday 17 October. In addition, the College has been able to source a number of large capacity pumps to assist in draining the area. Water is being removed at approximately 700L per second via these processes (the equivalent of 2.5 megalitres per hour, which is roughly the volume of water in an Olympic-sized swimming pool that is being drained per hour). It was estimated on commencement that it would take 4-5 days to drain the Park. At the time of writing, this would seem to be a reasonable estimate – indicating that the Park contained around 200-250 megalitres of water after it receded naturally to be captured as a lake within the levy system;
- Once the Park has been drained, an assessment of the restoration activities required to restore the playing surfaces and the tennis/netball courts can be made;
- Whilst repairs to bridges are unlikely, repairs to the road network will be required. The majority of loose/small diameter gravel has been scoured from surfaces;
- A clean-up crew commenced cleaning the internals of the buildings on Monday 17 October which is estimated to take 2-3 weeks. There is some, but limited, damage to doors, joinery etc;
- Losses from a minor equipment perspective are being catalogued. This is likely to be limited predominantly to fridges and sporting equipment. Very few items within the Grounds Shed or Education Outdoors have been lost;
- The College maintains insurance for these circumstances. We will be working through the process over the coming weeks with an assessor appointed by the insurers to progress the process from here;
- At this preliminary stage, guidance is that the Park will not be operational for the rest of Term 4. This will be updated once matters, as outlined above, are further progressed. Unfortunately, similar to 2016, significant mud/silt levels are being observed underneath the receding water that will lead to challenges in the restoration of the playing surfaces;
- The College rowing pontoon infrastructure was also impacted as a result of the event. This is being assessed by an engineer with a resultant restoration plan pending. It is likely that this precinct will not be operational until mid-November; and
- From a co-curricular perspective, the main sports impacted as a result of the flood event are tennis, rowing and cricket. Alternative venues and arrangements are being progressed to manage these offerings during Term 4.
A common question this week has been “would it be possible to increase the levy banks at the Park to protect it from events like this?” The answer is “Yes – but it would be a very significant project. Our current levy system protects the Park well from minor and moderate flood events, but events of this magnitude are well outside current design parameters. A provisional estimate in 2018 was that increasing the height of the levy banks and bridges at the Park to protect against a 1 in 100 year flood event would be around a $15 million infrastructure project. A project of that scale would divert resources away from our main campus upgrades for a long period of time – perhaps 10 years or so – and so is likely unviable in the context of ensuring the College can continue to support and modernise its core teaching and learning facilities in the future”.
I’d like to acknowledge the significant work of the College Works and Grounds team over the course of the past week in their flood mitigation and recovery efforts. I’d also like to acknowledge the significant loss that these teams are feeling at the moment as they work to restore areas that were so well presented prior to the flood event and thank them for their resilience and positive attitude they bring to their roles.
Further reports will be available, including financial impacts to the College associated with the event, as these matters progress over the coming weeks.
The College is also closely watching weather forecasts over the coming days!