balancing fish passage with hydraulic and cost efficiency
TRANSCRIPT
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Balancing fish passage with hydraulic and
cost efficiency in structures
Louise Dutton, Principal Environmental Officer
Far North District, Northern Region
Department of Transport and Main Roads (TMR)
Institute of Public Works Engineering Australasia (IPWEAQ) Roads Symposium
11–13 June 2019
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Contents
1. Background
2. Constraints and challenges of the past
3. Collaborative approach with the Department of Agriculture and Fisheries (DAF)
4. Amendment of the accepted development requirements
5. Development of standard drawings
6. Research into the hydrodynamics of fish passage
7. Ongoing challenges.
Image courtesy of the Department of Agriculture and Fisheries.
IPWEAQ Cairns Symposium l 11–13 June 2019
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Background
Current science and engineering
• Fish move at all life stages and sizes in
Australia (7mm to 6000mm)
• Adults are dispersing after spawning
and juveniles are dispersing after
hatching
• Regular movements of freshwater fish
between rivers, floodplains or the sea
to breed and grow are critical for the
survival of native fish populations
• The ‘boom and bust’ cycle leads to
many unique migratory patterns among
our fish. IPWEAQ Cairns Symposium l 11–13 June 2019
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Key fish passage barriers
• Vertical drops greater than
100mm
• Flow velocity
• Changes from light to dark
• Depth of flow
• Turbulence
• Swimming ability:
Australian fish generally migrate upstream as juveniles
Swim less than 0.3m/s steady or 0.7m/s burst speed over short distances.
IPWEAQ Cairns Symposium l 11–13 June 2019
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Constraints and challenges
IPWEAQ Cairns Symposium l 11–13 June 2019 Image courtesy of the Department of Agriculture and Fisheries.
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Constraints and challenges
Waterway barrier works
• Applied to culverts since circa 2008
• Development approvals for constructing
new or modifying existing structures
• A number of iterations of self-assessable
codes
• Challenging requirements for hydraulics,
flooding, structural integrity, cost-efficiency
• Largely managed as an environmental
issue. Limited integration into hydraulic or
structural design processes.
Bridges24%
Major Culverts
38%
Minor Culverts
38%
TMR impacted structures
12,668 crossings
with DAF
waterways
Note: These numbers are estimated from TMR datasets and spatial
analysis.
IPWEAQ Cairns Symposium l 11–13 June 2019
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Example waterways for waterway barrier works
IPWEAQ Cairns Symposium l 11–13 June 2019 Image: Ten Mile Creek culvert works completed on the Peninsula Developmental Road, 2018.
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Constraints and challenges
Fish passage
challenges
Hydraulic and structural design
Constructability
Cost
Clarity of assessment requirements
IPWEAQ Cairns Symposium l 11–13 June 2019
Image courtesy of the Department of Agriculture and Fisheries.
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TMR – DAF collaboration
TMR
Hydraulic design
Structural design
Environmental process
DAF
Fish biology
Fish passage limitations
Fish habitat assessment
IPWEAQ Cairns Symposium l 11–13 June 2019
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Collaboration through mutual understanding
Hydraulics
• TMR interests = 10, 20, 50 year average recurrence interval (ARI)
• DAF interests = 1, 2 ,5 year ARI
• Average velocity is the peak not the entire event.
Site Assessments
• Mutually agreed methodology for fish habitat assessments.
Structural design
• Alternative design requirements for accepted development requirements (ADR) through understanding of TMR constraints
• i.e. depth of cover, reinforced concrete pipe (RCP) thickness.
Clarity of requirements
IPWEAQ Cairns Symposium l 11–13 June 2019
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Collaboration through mutual understanding
TMR
DAF
Amended ADR
Benefits
• Re-sleeving and inverts of existing culverts allowed
on structures not previously built under codes or
development approval (DA)
• Depth of cover restrictions not applicable if culvert
commences full flow at greater than or equal to two
year ARI
• Invert thickness increased from 100mm to 200mm
with the inclusion of ramped apron.
Residual constraints
• In order to re-sleeve, existing culverts need to
meet the requirements for ADR requirements for
new culverts
• Costly ‘jacking in’ of additional cells where
re-sleeving greater than 100mm thick
• Baffle design.
IPWEAQ Cairns Symposium l 11–13 June 2019
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Development of standard
drawings and functional
specification
IPWEAQ Cairns Symposium l 11–13 June 2019
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Development of standard drawings
Standard drawings provide potential benefits through:
• ease of implementation – no registered professional engineer (RPEQ)
• consistency and clarity of requirements
• confidence for suppliers to potentially develop pre-cast RCPs and reinforced
concrete box culverts (RCBCs).
IPWEAQ Cairns Symposium l 11–13 June 2019
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Functional specification – incorporation of assessment
for fish passage
Environmental assessment
• Existing fish habitat values
• Natural barriers to fish passage.
Hydraulic assessment
• Include one, two and five-year ARI
events
• Hydrograph to show lead and lag
flows
• Use ADR as the base case for design
• Inclusion of baffles and burial in
hydraulic assessment.
IPWEAQ Cairns Symposium l 11–13 June 2019
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Research into
hydrodynamics
for fish passage
in box culverts
IPWEAQ Cairns Symposium l 11–13 June 2019
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Research – box culvert hydrodynamics for fish passage
• Purpose to address knowledge gaps
• Funded in January 2019
• Research by University Queensland
(UQ) hydraulics engineer
• Focus on:
Low velocity zone characteristics
Mathematical relationship between
average velocity and low velocity zone
width and velocity
Alternative wall treatments to maximise
low velocity zone.
Source: Cabonce, J. Wang, H. & Chanson, H (2015) Ventilated Corner Baffles to Assist
Upstream Passage of Small-Bodied Fish in Box Culverts. IPWEAQ Cairns Symposium l 11–13 June 2019
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Research 0150 – Box culvert hydrodynamics for
fish passage
• Developing design methodology
for optimising fish passage for
less-than-design flows
• Comparative assessment of
baffles
Rectangular (ADR)
Triangular
Longitudinal beam.
Research outcomes expected end of July 2019
IPWEAQ Cairns Symposium l 11–13 June 2019
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Ongoing challenges
Fish passage
Pipe culvert designs
Cost effective rehabilitation of steel culverts
Pre-cast baffles /
rougheningEmbedding
fish passage in structural
design
Accurate mapping of fish
passage priority
waterways
IPWEAQ Cairns Symposium l 11–13 June 2019 Image courtesy of the Department of Agriculture and Fisheries.