Lower Macleay Flood Levee Audit Report

Introduction

Cover of Lower Macleay Flood Levee Audit Report

The Lower Macleay Flood Levee system was designed and constructed in the 1960’s. Since this time, the condition of the levees has deteriorated due to a lack of maintenance.

In 2015/16 audits were conducted on all of the Lower Macleay levee systems to assess the current conditions of the levees and provide recommendations to remediate any issues found. This will enable the deficiencies to be identified and planning for remediation to commence.

Scope of audit

The scope of the audit included but was not limited to:

  1. Compilation of all the known reports and information available on the levee and a summary of their findings and recommendations.
  2. Comparison of the levee design crest levels, existing crest levels and flood levels. This was undertaken by:
    1. Obtaining the levee design crest levels and flood levels from either:
      1. The original design plans,
      2. Previous flood studies, or
      3. Previous experience with road designs in the areas.
    2. Completing a survey of the levee to confirm existing levels.
    3. A defects inspection (visual) of the levee to identify areas of anomalies, such as missing levees, low sections, localised depressions, and signs of erosion/scour or instability.
  3. Geotechnical testing and stability assessment of the urban levees (no assessment was completed on the rural levees).

The following items were not included in the scope of the audit although it is recommended they be carried out at a later date:

  1. Preparation of a cost estimate for the remediation of all identified defects and a total cost to repair the levee.
  2. Preparation of a condition rating for the levee based on the risk of failure and the likely consequence of failure.
  3. Preparation of an Operation & Maintenance Manual. It is proposed that one document for the entire Lower Macleay flood levee system be developed.

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