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Annex 7 - Engineering Specifications
Attached to the e-mail DA Application - Noosa Oyster Project (2 of 3).
Annex 3: Engineering specifications and rectifications
A summary of the engineering specifications and substrate rectifications is given below for ease of
reading only. For detailed drawings refer to Annexes. The formatting of this section conforms to that
of the drawings but is inconsistent with that of other sections in this submission.
The specifications and rectifications have been certified by a Registered Professional Engineer of
Queensland (RPEQ).
NOTES FROM DRAWING 00
1. PURPOSE & PERFORMANCE
1.1. Works are to restore rock oyster ecosystems throughout the Noosa River estuary at sites that
meet site suitability criteria and positively interact with current human uses.
1.2. Works may provide some erosion protection; however, they have not been designed
specifically for this purpose.
1.3. As the works do not include geotextile underlayer, some settlement is to be expected and has
been factored into the design.
1.4. Module layouts have been developed to allow water flows through the structure to reduce
siltation, however some siltation is to be expected and has been factored into the design.
Module layouts are to be laid as reef patches and may be curved or shaped to reflect the local
bathymetry and specific constraints of each restoration site.
1.5. Inundation and overtopping of the oyster reef patches during higher tides and flood events is
to be expected.
2. SCOPE OF WORKS
2.1. Phase I. Deployment of restoration substrates in modular forms at 4 restoration sites.
2.2. Phase II. (SUBJECT TO SEPARATE APPROVAL) Deployment of restoration substrate at
additional sites and/or to augment or maintain existing sites throughout the estuary as
funding allows. Additional sites to be progressively selected from within the identified
Restoration Zones (refer Note 5).
2.3. Works may include seeding of substrate with oyster spat and/or live oysters. Oysters to be
sourced from brood stock within the Noosa River and/or culture stock from oyster gardening
within the Noosa River.
2.4. Works may be staged. Individual sites may be staged subject to engineer’s certification.
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2.5. Deployment of navigation buoy(s) at each site and signage in accordance with permit
conditions.
2.6. Works to be undertaken in accordance with the Project Restoration Plan.
2.7. Monitoring and Maintenance, as required (refer Note 4.)
2.8. Works may need to be adapted in response to climate change, depending on monitoring of
habitat health.
3. NOOSA RIVER FISH HABITAT AREA, MATTERS OF STATE ENVIRONMENTAL SIGNIFICANCE &
MARINE PLANTS
3.1. The objective of the works is to restore oyster-dominated ecosystems to the Noosa River
estuary including within the Noosa River Fish Habitat Area.
3.2. Two of the Phase I Restoration Sites, Tewantin and Goat Island, are within the Noosa River
Fish Habitat (A) Area. The Noosa Sound East and Noosa Sound West restoration sites occur
outside of the Noosa Fish Habitat Area. The Phase II Restoration Sites have not been selected
but will be within the Noosa River Fish Habitat Area (except for any further works in Noosa
Sound restoration sites).
3.3. Works to occur within the identified Restoration Zones, within 30m from shore, in water
depths less than 2m below MLWS. The exception to this is the Tewantin site where works are
proposed on existing rocky substrate, or in the future where otherwise approved in writing by
MSQ.
3.5. Phase 1 works results in temporary impacts to sparse marine plants at Tewantin site only.
3.6. Works are NOT to impact on existing terrestrial vegetation (including vegetation within
mapped MSES).
3.7. During construction, plume is to be minimised and monitored visually to ensure no impacts to
adjacent marine plants. Turbidity monitoring to be undertaken in the event that it extends
within 5m of mapped seagrass beds (Refer Project Restoration Plan Section 6.4).
4. MONITORING & MAINTENANCE
4.1. Restoration substrates to be monitored periodically and after major storm events in
accordance with the Project Restoration Plan.
4.2. Maintenance to be undertaken as required. This may include:
· Reprofiling and/or placement of additional rock on oyster reef patches to reinstate design
levels and profiles after expected settlement has occurred. Ideally this would occur 12
months after deployment but may be subject to timing of other works. Where limited
natural settlement of oysters is experienced (nominally <200mm) and the crest remains
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within the target depths for oyster growth, maintenance works are not required. Additional
rock only to be placed on existing oyster reef patches where monitoring indicates that this
will enhance the habitat (not where existing habitat is established and healthy).
· Placement of additional oyster cultch (seeded or unseeded) and/or live oysters, onto a
oyster reef patch is not to exceed 10kg/m2 to maximise interlocking of the cultch or oysters
with the rock.
· Removal of displaced rock and or oyster shell, if found more than 5m outside the
restoration site, as part of monitoring, and if resulting in negative impacts, is required.
5. RESTORATION ZONES, RESTORATION SITES, RESTORATION FOOTPRINTS
5.1. Restoration Zones have been identified as listed below. For more detailed images of each
zone, refer drawing NROR-2021-01. The Restoration Zones have been developed based on
Habitat Suitability parameters and Restoration Suitability parameters as detailed in the
Project Restoration Plan.
Zone 1. Main Channel
Zone 2. Noosa Sound
Zone 3. Weyba Creek
Zone 4. Lake Weyba
Zone 5. Lake Donella
5.2. Restoration Sites are identified within each Restoration Zone based on mapping of site-
specific constraints, knowledge of past oyster bed occurrences (where possible) and adoption
of minimum distances outlined in Table 1.
Table 1: Constraints and minimum distances to determine restoration sites
Existing Feature or Habitat Constraint or Minimum Preferred Proximity to Existing
Required Distance Habitat
Landward extent water depth MHWS -
Seaward extent water depth 1m seaward of selected depth -
(1 below MLWS preferred; 2m
below MLWS maximum)
Rocky reef 2m* Within 500m
Extant oyster ecosystem 2m Within 250m
Historical oyster ecosystem - Within 250m
Restoration on historic sites
where known and practical.
Terrestrial Vegetation 0m -
(including mapped MSES)
Mangroves including 2m -
pneumatophores
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Fallen trees and timber in 2m -
waterways
Other marine plants (including 10m** Within 500m of seagrasses
seagrasses)
Mobile seabed 0m -
Distance from MHWS Less than 30m*** -
Small craft channels (MSQ 10m -
beacon to Beacon Centreline)
Tidal works 30m -
Moorings 30m from mooring (providing -
minimum 5m from vessel on
mooring)
Foreshore access 10m -
In-water urban utilities 5m -
(submarine cables & pipelines)
In-water transport 30m -
infrastructure (cross river cable
barges, ferry terminals etc)
*Substrate may be placed on existing rocky reef where the substrate is not supporting significant
habitat.
**Unless approval is granted for enhancement of significantly degraded areas.
***Except with written agreement of MSQ to extend further offshore (e.g. Tewantin Site).
5.3. The Restoration Footprints are the area of riverbed encompassed by a group of restoration
substrate reef patches. Restoration Footprints are to be within the selected Restoration Sites.
Phase I Restoration Sites are listed below and detailed on drawing NRN-2021-03, -04, -05 & -
06.
• Goat Island Restoration Site
• Tewantin Restoration Site
• Noosa Sound West Restoration Site
• Noosa Sound Easts Restoration Site
NOTES FROM DRAWING 02
1. MODULE LAYOUT OF RESTORATION SUBSTRATE:
1.1. Restoration footprints (i.e. collection of oyster reef patches within a restoration site) are to be
defined by constraint mapping and minimum required distances to protect marine plants and
public/private assets as per Table 1 on NROR-2021-00.
1.2. Rock substrate is to be laid as reef patches, as per the drawings for each restoration footprint
and consistent with the design module requirements. Reef patches may be curved or shaped
to reflect the local bathymetry and specific conditions and constraints for each restoration
site.
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1.3. Footprint of reef patches to consider construction practicality and tolerances. This includes:
1.3.1. Allowance for a minimum distance from MHWS sufficient to allow for placement of
design rock grading.
1.3.2. Minimum distance of 1m from seaward extent to allow for construction tolerances in
deeper water.
1.4. Crest width to be minimum 1m in any direction. Larger crest widths (up to nominal 10m) are
more desirable as they provide a larger area for oyster growth.
1.5. Access space between reef patches to nominally be 1m - 4m although larger spaces may be
desirable depending on site configuration or expected sediment transport or siltation.
1.6. Final layout of reef patches to be determined by certifying coastal engineer prior to
construction and take into consideration local bathymetry, geometry of Restoration
Footprint, adjacent land uses, presence of erosion, existing infrastructure, wave action, water
flows, sediment type, expectation of siltation and any other relevant factors.
2. MATERIALS
2.1. Rock
2.1.1. Grading to be stable for individual locations and provide voids, rugosity and habitat
complexity suitable for habitat growth as per design reef patches in drawings.
- Phase I sites. Rock grading to be 150 - 500mm diameter with 50% over 300mm.
- Phase II sites. Rock grading for individual sites to be determined by coastal engineer
for stability and suitability prior to construction
- Individual larger rocks may add to rugosity and may be incorporated provided that it
fits within the profile of the reef patch and achieves good interlocking.
2.1.2. Rock to be igneous or metamorphic rock suitable for use in the marine environment.
Rock to be sound, hard, durable and angular. Rock to be clean and free of topsoil and
organic matter.
2.1.4 Rock characteristics to be in accordance with the Table 2.
Table 2: Rock characteristics
Parameter Standard Requirement
Density AS1141.6.1 >2600kg/m3
Water absorption AS1141.6.1 <1.5%
Abrasion resistance (Los Angeles) AS1141.6.23 <25%
Wet Strength AS1141.6.22 >170kN
Salt Attack (Sodium Sulphate Soundness) AS1141.6.24 <6%
2.2. Cured Oyster Shell
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2.2.1. Shells to be sourced from Mooloolaba Fish Market and local seafood restaurants.
Shells to be cured (by desiccation) in accordance with Queensland End of Waste Code
– Oyster shells (ENEW07278317) as per the Waste Reduction and Recycling Act 2011.
2.2.2 Shells to be whole not fragments.
2.2.2. Shells may be washed in freshwater prior to deployment as composite substrate or as
cultch (unseeded or seeded with oyster spat).
2.3. Seeded Oyster Cultch
2.3.1. Cured oyster shell to be seeded with local oyster spat to enhance oyster growth and
recruitment locally.
2.3.2. Live oyster brood stock to be grown in oyster bags within the Noosa River as part of
oyster gardening project (with permit).
3. OYSTER REEF SUBSTRATE
3.1. A rock only substrate or a composite substrate of rock (as specified) mixed with cured oyster
shell may be used as a restoration substrate.
3.2 The composite substrate to be up to 10% shell to ensure substrate stability is maintained.
3.3 Oyster shell volume in composite may be increased to 20% shell subject to certifying
engineer's approval. A higher component of shell may be considered subject to constructability
and monitoring outcomes.
3.4. Shell to be evenly mixed through the rock, when used as a composite, to achieve good
interlocking and not placed in alternating layers. Mixing to occur in small volumes on the
barge immediately prior to placement to avoid shell damage due to rehandling.
4. CONSTRUCTION:
4.1. Reef patches expected to be constructed using an excavator mounted on a shallow-draft
barge. Excavator to be fitted with GPS position control (or have equivalent system in place to
enable accurate placement).
4.2. Substrate Placement
4.2.1. Rock shall be placed to be well interlocked and stable.
4.2.2. Rock shall be placed to provide an irregular, organic finish (within nominated
tolerances). This will assist in enhancing the stability of the seeded oyster cultch.
4.2.3. Rock placement to be clear of any existing vegetation and minimum required
distances (NROR-2021-00 Note 5.2).
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4.3. Placement tolerances
4.3.1. ± 0.5m horizontal tolerance
4.3.2. ± 0.2m vertical tolerance (except crest)
4.3.3. Crest level to be no higher than MHWS and not more than 0.2m below MHWS at
time of construction. Crest height to be adjusted, as required, to match oyster
recruitment heights at a given site.
4.3.4. Settlement of rock is expected to lower the reef patch profile over time.
4.4. Anchoring of construction vessel not to impact on marine plants. No anchoring within 100m
of submarine cables.
5. SEEDED CULTCH, UNSEEDED OYSTER CULTCH, LIVE OYSTERS
5.1. Seeded oyster cultch, unseeded oyster cultch and/or live oysters are to be placed across the
crest of the oyster reef patches and would typically extend down the batters of the rock
substrate. Seeding of areas in close proximity to the seabed is to be avoided.
5.2. Seeded Oyster Cultch and/or Live Oysters are to be placed as a single layer. Stacking or
layering of cultch is to be avoided. (Target placement volume of 5kg/m2/ with maximum
10kg/m2).
5.3. Seeded Oyster Cultch and/or Live Oysters are to be placed by hand into voids within rock
substrate and interlocked as far as possible to limit loss from the structure.
5.4. Placement to target more protected areas (less exposed to wave and current) preferentially.
6.0 RECTIFICATIONS
6.1 Rectifications, where needed, are to be undertaken as per Table 3.
Table 3: Rectifications
Issue Rectification Response Specific Rationale
Requirements
Settlement No rectification required Settlement of rock into
of where: sandy substrate is
Restoration - settlement is limited expected. The design
Substrate (nominally <200mm) and targets a crest height of
the reef patches at
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crest remains within target MHWS such that
oyster growth depths settlement may result in
OR final crest heights that
- oyster habitat is established remain within the target
and healthy range for oyster growth.
The objective of the
structure is to enhance
oyster growth. As such,
rectification is
undertaken only as
required to achieve
these objectives.
Reprofile and/or place Reinstate design Maintain substrate
additional rock if required. levels. Works to be profile as required to
undertaken in ensure structure
accordance with achieves optimal habitat
design requirements. potential.
Target works ~12 months
after initial deployment if
possible to optimise
benefit and reduce
potential for impacts to
developed habitat.
Siltation In the event that significant Final structure to be Siltation is expected. The
siltation results in burial of consistent with the design facilitates water
significant portions of oyster design principles, flows through the
habitat growth zones, profiles and structure to minimise
modification of the structure requirements. siltation and crest at
may be considered. MHWS reduces potential
for siltation to impact on
Sediment not to be target growth zones.
disturbed.
Rock Rock found >5m outside Rock to be placed Rock grade is stable if
displaced Restoration Site to be within design profile. applied as per module
from reinstated onto structure (or design and specifications
structure removed). of design wave and
current conditions.
Individual rocks may be
displaced in response to
design wave event.
Slumping of rock may be
experienced along the
seaward edge of reef
patches.
Shell Shell found >5m outside Shell is not inherently
displaced Restoration Site to be stable in design
from reinstated onto structure (or conditions. Design
structure removed) if required. enhances stability as
much as possible
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(including through interlocking with
shell, seeded rocky substrate.
shell clutch
or live
oysters)
Oyster Placement of additional Total volume of loose Benefit of placement of
growth is oyster cultch (seeded or shell (including additional oyster shell
lower than unseeded), and/or live existing shell) not to subject to monitoring
target oysters to enhance local exceed 10kg/m2. results and ecological
densities recruitment. Placement to be in assessment.
accordance with
design requirements.
Total loose shell
volume in areas
where composite
substrate is used not
to exceed 10%.