Floodplain engineering services

Council's flood mitigation assets are valued at a replacement cost of over two hundred million dollars.

Ulmarra Rock ArmouringFlood Mitigation Infrastructure

Council currently has under its control:

  • 110 km of levee 
  • 18 km rock protection 
  • 50 bridges 
  • 500 floodgates 
  • 250 flood mitigation drains

Council's flood mitigation assets are valued at a replacement cost of over two hundred million dollars.

Council carries out regular inspections of its infrastructure to monitor their condition and ensure proper maintenance. The outcome of these inspections is entered into Council's Total Asset Management System as part of Council's development of its annual Maintenance Program.

Recently completed major projects include:

  • Ulmarra riverbank rock armouring
  • Grafton levee rehabilitation near the Crown Hotel
  • Farlows Drain bridge and floodgates
  • Maclean levee near the old rowing club site
  • Blaxland Creek rehabilitation projects

The 2001 floods - the worst in fifty years - February 2001

With the onset of heavy rain and the receipt of flood warnings for the Clarence River from the Bureau of Meteorology, Council staff implemented flood preparation procedures on Thursday, 1 February 2001. The following peak flood levels were attained:

  • Grafton: 6.66 metres at 1900 hours on 3 February 2001.
  • Ulmarra: 5.30 metres from 1800 hours on 3 February to 0700 hours on 4 February.
  • Maclean: 2.68 metres from 2100 hours to 2200 hours on 4 February.

The outstanding feature of this flood was the excellent benefit derived from the South Grafton levee, where the usual evacuations were no longer necessary and considerable flood damage to private property was avoided.

However as the flood waters receded, it became apparent that significant damage had occurred to our levee system. Areas of concern were listed for further investigation, and an assessment of all damage was carried out once river levels were back to normal.

The event was declared a natural disaster, thus enabling Council access to the natural disaster relief program to fund the cost of repairs. Council’s assets performed their function well during this event and the benefits to the community were significantly enhanced by the now completed South Grafton levee.

 

Lawrence March 2001 Grafton March 2001

Lawrence March 2001

Grafton March 2001

 

March 2001

Although the Valley was still recovering from the impact of the February flood, heavy rainfall was again experienced on 8 and 9 March 2001. The Bureau of Meteorology issued several flood warnings including a predicted peak level of 8.1 metres on Saturday, 10 March 2001.

Damage from the February 2001 flood had not yet been repaired as the process of seeking funds from the state and federal government Natural Disaster Relief Program naturally takes time. Significant damage to some levees in rural areas meant that nearby property owners no longer had the protection normally provided by our flood mitigation infrastructure.

However the condition of levees in the urban areas of the Clarence Valley remained sound, but close monitoring was important throughout the weekend. Council's staff carried out all of the usual preparatory measures to ensure floodgates were sealed off prior to the weekend. Clarence River County Council staff maintained close contact with response teams from Grafton City Council and Maclean Shire Council.

With the peak flood level forecast of 8.1 metres, the SES decided to commence voluntary evacuation of Grafton as this flood height would have been close to the crest level of the levee. Fortunately the situation eased during the afternoon of 10 March, and the flood peaked at 7.7 metres without threatening to overtop the levee at Grafton.

 

Maclean March 2001 Brushgrove March 2001

Maclean March 2001

Brushgrove March 2001

 

A peak of 3.26 metres was experienced at Maclean on Sunday, 11 March and again the levee did its job in protecting the town without overtopping.

However overtopping did occur at the Ulmarra levee during the night of 10 March and also on Sunday, 11 March 2001.The earth levee north of the Ulmarra ferry suffered considerable scouring and one section was completely washed away. The levee still provided valuable protection to the town by shielding properties for some considerable time.

This was the largest flood since 1950 in terms of peak flood level at the Prince Street gauge.

Flood Damage Restoration Program

With State and Federal funding assistance Council has since completed a $5.2 million dollar works program to restore infrastructure damaged during the February and March 2001 floods.

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