Iron Pot Creek Drainage and Erosion Plan
Purpose
Iron Pot Creek and associated tributaries have areas of extensive erosion, caused by a combination of historical land clearing, urban development and construction of infrastructure. Over time the creek channels have deepened and widened, generating an increase in flow volumes and velocities that has caused extensive bank erosion, massive mobilisation of sediment and potential damage to private property. The types of erosion present include head cuts, lateral bank erosion, bed lowering, tunnelling, and bank slumping.
AWC and Bligh Tanner Consulting Engineers collaborated in providing a holistic erosion and bank stability strategy. The team developed strategies to reduce the erosivity of catchment runoff and provided in-stream responses that are geomorphically and ecologically appropriate.
Objectives
- Geomorphic investigations, including erosion condition assessment. Assessment of creek condition was undertaken using a Level IV Rosgen stream assessment including: stream character, channel materials, sediment sampling and erosion potential, stream bank erosion index and soils.
- Ecological investigations. Assessment of vegetation within the streamline and work area was undertaken using a combination of Regional Ecosystem mapping by DEHP, recent aerial photography and ground-truthing the length of Iron Pot Creek on foot. All flora, targeted searches for threatened flora species and habitat features were recorded.
- Hydrologic and hydraulic modelling. Bligh Tanner undertook an analysis of flow rates, flow velocities and soil conditions.
- Provision of legislative approvals for in-stream works. A full review of relevant legislation and approvals required for the proposed works was undertaken.
- Liaison and consultation with Council and neighbouring property owners.
- Prioritisation of remedial work areas using a risk assessment approach. Priority locations for rehabiltiation were selected based on the degree of instability and proximity to private property.
- Development of erosion/bank stability mitigation designs as part of the Creek Rehabilitation and Management Plan.
- Detailed design drawings and supporting cost estimate.
Partners & Stakeholders
- Ipswich City Council
- Bligh Tanner Consulting Engineers
Outcomes
- Provision of a holistic Plan that is sensitive to ecological considerations, legislative requirements and Council’s maintenance requirements.
Project Facts
Project Value: $70,000
Challenges: Working with dispersive soils in a high energy creek in close proximity to private property in a high profile area.