Resilient Asset Management: Provide

These case studies show how a asset management strategy can save money by proactively protecting critical infrastructure.

Kyogle Flood Mitigation Works and Water Supply Augmentation 

Kyogle is a town located in the headwaters of the Richmond River in the Northern Rivers region of northern New South Wales. It is located 758km north of Sydney and 32km north of Casino on the Summerland Way, close to the Queensland border. It falls within the local government area of Kyogle Council. Cattle grazing, dairy farming and forestry are the primary industries.
 
The Kyogle Town Water Supply services approximately 3,500 people and growth up to 4,500 people is anticipated over the next 20 years.  At the start of the Millennium, Kyogle Council participated in a pilot project for small councils to undertake an Integrated Water Cycle Management Process which helped Council consider their future requirements using a catchment wide approach. Council realised that the solution to the flooding problem in Kyogle and the solution to the water supply were integrated and needed to be considered holistically.
 
After decades of planning and more than two years of construction works, the Kyogle Flood Mitigation and Water Supply Augmentation was completed in 2018. The project value was $9.4 million, with $7.2 million combined funding from the NSW Government. The project improves drought and flood resilience, reduces water treatment and operational costs, increases treatment capacity and allows for more consistent water quality. The project's major elements included:

  • Modification of the existing in-stream weir and construction of an award winning, innovative fish-way.
  • Upgrade of the existing river extraction pumping station
  • Construction of a 200ML off-stream storage (OSS) dam, preliminary treatment and pumping facility.
  • Upgrade of the Water Treatment Plant to meet current water quality standards and increased capacity for growth.
  • Flood modification works combined with the OSS civil works contract.
Above: Kyogle Flood Mitigation and Water Supply Augmentation

In March 2017, a severe weather event meant that the flood modification works got their first real test. The off-stream storage ensured that the water supply raw water source was not affected by flood waters, making the water supply itself more resilient to natural disasters and climate change impacts by protecting the raw water source from contaminants that are contained in flood waters. The flood way opened a relief channel early which meant the peak of the flood was lower in town. The levee bank also provided protection to the low lying areas which still flooded but with more warning and reduced impact as it was not fast flowing water as in previous events.

Above: Kyogle is more resilient to flood now.

This case study demonstrates how resilience can be integrated into the planning phase of the asset management lifecycle to deliver quality outcomes, provide resilient water supply and solve a range of issues faced by Local Government in delivering critical infrastructure resilience. 

Upper Hunter Shire’s Resilient Bridges

Upper Hunter Shire is a local government area located in the Hunter Region of NSW, approximately 250km north of Sydney. The local government area covers approximately 8000km² of rich agricultural land and has a population of approximately 14,500 people.

Several communities within the Upper Hunter Shire are at risk of flooding. Upper Hunter Shire Council understands that taking steps to prevent flood damage may cost more money in the short term but could save a lot in repair and replacement costs for decades to come.

Upper Hunter Shire’s cohesive asset management strategy identifies their assets, the hazards they are vulnerable too and the level of risk. This has led Council to adopt a strategy of building both high and low bridges. 

The high bridges are designed to have high decks above flood level and a clear span so that logs and debris during a flood event can easily pass through without causing structural damage. The low level bridge height is set so that when larger debris and logs are being carried by the higher velocity floodwaters, they pass over the structure rather than under or into it. This means that critical and non-critical assets can be inspected and reopened as soon as possible following a flood.

Above: The Upper Hunter Shire Council's has high and low bridges builds resilience to flooding.
  
This case study demonstrates how resilience can be integrated into the design aspect of the asset management lifecycle to provide engineered protection for bridges from flood-related damage and destruction. 

Improving Capability of Infrastructure to Withstand Flooding

The City of Wagga Wagga, the largest inland city in NSW, has been subjected to large-scale flood events throughout its history. Risk sources include the Murrumbidgee River and overland flooding from stormwater runoff.

In December 2010, with the Murrumbidgee River already at 7m, 65mm of rain fell within 3 hours overnight. The new predicted peak for the river was 9.7m, and the stormwater runoff overflowed the catchments of Wollundry and Tony Ireland Lagoons, with subsequent flood damage to the adjacent council buildings, including the library, art gallery and basement of the civic centre.
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Above: Public spaces in Wagga Wagga and the basement of the civic centre were under water in the 2010 floods.

With the assistance of Riverina Water County Council, Wagga Wagga Council installed a temporary pump and pipeline within 10 hours to pump from the lagoon directly into the river.

Above: A pump and pipline was set up to lower the water level of the lagoon and pipe the flood water directly to the Murrumbidgee River.
    
Although the temporary solution worked, a better permanent solution was needed.

The council have implemented improvements including:

  • Increasing the capacity of the largest catchment lagoon; 
  • additional floodgates between the catchment lagoons and the river;
  • additional bidirectional pumps; and
  • additional outflow pipelines.
Above: This bidirectional pump is part of a permanent solution for Wagga Wagga.

The new system of pumps and weirs allows the council to reduce lagoon level during flood events, but also ahead of expected flooding in preparation for stormwater runoff. 

A planned green-space levee between the buildings and the lagoon will create a last line of defence, and will also incorporate seating, artwork and natural features.

This is a picture og the Kyogle Council's logo.