Sunshine Coast Regional Sand Sourcing Study

Presentation Outline

• Drivers - why Council needs access to sand sources for ongoing coastal management

• Overview of existing sand sources - challenges and constraints

• Using offshore sand sources and methods to place

• Framing a long term strategy

Sunshine Coast Sand Sourcing Study

Why does Council need sand?

• The Shoreline Erosion Management Plan (SEMP) is a 10-year action that outlines preferred management options to address priority erosion threats

• Beach nourishment is preferred option for a number of priority areas

• Current sand reserves are finite; expansion of current reserves constrained by legislative and environmental constraints

• Future climate change will only exacerbate the need for sand

Sunshine Coast Sand Sourcing Study

Why is this a preferred option?

• A wide sandy beach provides a buffer to severe weather events and reduces the erosion threat to land based assets

• The beach response to erosion mimics nature

• Helps to maintain recreational values associated with beaches

• Sunshine Coast social and economic values dependent on access to healthy beaches – SLSC

• Proven benefit, delays the need for hard structures

Beach Nourishment

Sources considered:

1) Estuarine reserves (MaroochyRiver Mouth and Northern Pumicestone Passage)

2) Purchasing and transporting commercially extracted marine sand (from Moreton Bay)

3) Identification and allocation of an offshore reserve

Sand Sourcing Options

Description

• Council is currently permitted to access up to 10,000 m3/year for shoreline management

• Recent approval to access an additional 40,000 m3 for shoreline nourishment between LameroughCanal and Bells Creek

• Highly constrained by environmental values - shorebirds, seagrass, marine megafauna, Fish Habitat Area, Ramsar

Northern Pumicestone Passage

Description

• Council is currently permitted to access up to 350,000 m3

over a four year period (works recently completed)

• Uncertain sand source for Maroochydore Beach beyond 2016

• Partially renewable - infilling rate estimated to be 50,000 m3/year

• Similarly constrained by environmental values -shorebirds, seagrass, marine megafauna, Fish Habitat Area

Lower Maroochy River

1 2

3 4

Description

• PBPL is permitted to extract sand from designated locations with Moreton Bay for port reclamation

• Sand from Spitfire Re-alignment Channel and north of Northwest Channel suitable for nourishment –but a finite resource under current allocation policy

• Sand placement via dredge bottom dumping offshore from the beach (noting draught restriction)

PBPL Commercial Sand Option

Operational considerations

• Sand placed close to the 8 m depth contour to create an offshore berm – no impact to beach use or amenity

• Slow migration landward under prevailing coastal processes

• Immediate “benefit” may not be recognised by the community

• In the medium term (up to a few years) the difference between offshore placement and direct placement on beach may be indistinguishable

• Trial proposed – placement with monitoring for 12 – 18 months

PBPL Commercial Sand

• Legal precedent - offshore sand reserves have provided approximately 6.4 million m3 of sand to Gold Coast Beaches since the mid-1980s

• Cost savings - closer proximity potentially reduces costs and time required for nourishment campaign

• Resource quality – previous surveys suggested areas of deep sand deposits fit for purpose

• Certainty – could provide a more permanent solution that will not depend on annual permits, timing of other projects and proponents

• Reduced social, amenity and environmental impacts - compared to estuarine options

Offshore Sand - Attractiveness

• Significant sand deposits throughout the southern half of the survey area (>9m in many locations)

• Generally thin layer of sand (0-3m thickness) over rock north of Point Cartwright

Offshore Sand Surveys

• Potential offshore sand source beyond the 20 m depth contour (i.e. seaward of the active littoral zone)

• Assuming a sand thickness of 4 m a total sand volume of 96 million m3

Offshore Sand Surveys

• Not constrained in the context of conservation planning

• Additional geotechnical survey required to confirm sand source quality and quantity

• Further environmental surveys (physical, chemical and biological) and impact assessment

• Allocation and approval

• Cost estimate to deliver 200,000 m3 of sand:o Offshore bottom dumping: $2.2 to $3.0 million o Nearshore “rainbowing”: $6.6 to $9.0 million

o Onshore pumping: $7.9 to $10.8 million

Approval for Offshore Sand

SCSSS - Strategy

Stage Timing Planned Activity

Stage 1 2015 - 2020 • Continue to utilise existing reserves• Trial of offshore placement with

commercial sandStage 2 By 2025 • Continue to utilise existing reserves

(if still available)• Supplement with use of commercial

sand (assuming trial successful)• Investigate/seek approval for offshore

reserves

Stage 3 Post 2025 • Continue to utilise existing reserves(if still available)

• Supplement/replace with offshorereserves