1. LT Creek Floodplain Risk Management Study & Plan
Community Consultation Meeting No 1
30th November 2016
Presented by: Richard Dewar, WMAwater Pty Ltd

2. Overview – NSW Floodplain Management Process
We are here

3. LT Creek Catchment 7km2

4. Floodplain Risk Management Study
Identify the magnitude of the flood problem
House floor levels v flood levels
How often are house floors inundated and what damages occur?
Measures to reduce the flood problem?
Flood Modification
Property Modification
Response Modification
Evaluate the Value of each Measure
Reduction in flood level
Cost
Environmental impact
Social impact
Levee
Raising
Warning
Raised floors

5. Community survey Mail-out and online version (Survey Monkey)
200 letters sent to residents and 20 to key stakeholders
Responses via post /Survey Monkey

6. Survey response summary

7. Survey response summary

8. Survey response summary

9. Survey outcomes 1 flood photo 1 person has flood debris marks
No above floor inundation
Concerns
Silt
Bluewater Avenue overflow & Croft Oval overflow
Suggestions
Dredging
Bluewater Avenue
Decrease insurance – individual inspections
Wetland containment area to limit sedimentation

10. Building Floors Inundated
Catchment Flood = rain over LT Creek catchment
1% AEP (100 year) nil
PMF 52
Lake Flooding = rain over Lake Macquarie catchment raising lake levels
1% AEP (100 year) 7
PMF 108
CONCLUSIONS
Very small tangible($) damages to buildings
Minor intangible damages – inconvenience, worry, risk to life
Hard to justify expenditure on flood mitigation measures

11. Flood Mitigation Measures
Flood Modification
Vegetation clearing – environmental impact
Levees – visual impact, cost
Dams, retarding basins – cost, no available space
Dredging – next page
Property Modification
House raising – little interest, cost
Flood proofing – only for commercial
New buildings – Development Controls
Response Modification
Flood warning – too quick response
Evacuation planning – infrequently used

12. Issues considered in the study report
Water Quality
Outside our Scope
Will be mentioned but cannot recommend measures
Dams in Newstan Colliery
Many there already
Will reduce peak flows and levels downstream
Risk of failure – subject to Dams Safety regulations
Will address in report
Mining Activities in Newstan Colliery
Unable to advise if affect flooding
Water quality outside our scope

13. Sea Level Rise & Lake Macquarie Flooding
Dredging
Suggested for water quality purposes
Nil benefit for flooding as no floors inundated
Environmental impact on flora and fauna
Not sustainable – must dredge forever
High cost – where to place spoil?
Dredging not permitted for flood mitigation in NSW
Sea Level Rise & Lake Macquarie Flooding
Addressed in separate FRMS
Council has initiated sea level rise adaptation plans
Flood warning for lake flooding being updated