Balancing fish passage with hydraulic and cost efficiency

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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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About us

IPWEAQ Cairns Symposium l 11–13 June 2019

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Queensland

Government’s

objectives for

the community


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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.


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Background


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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.


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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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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.


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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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Fish passage

challenges

Hydraulic and structural design

Constructability

Cost

Clarity of assessment requirements


Image courtesy of the Department of Agriculture and Fisheries.

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TMR – DAF

collaboration


13 |13 |

TMR – DAF collaboration

TMR

Hydraulic design

Structural design

Environmental process

DAF

Fish biology

Fish passage limitations

Fish habitat assessment


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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


15 |15 |

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.


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Development of standard

drawings and functional

specification


17 |17 |

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).


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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.


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Research into

hydrodynamics

for fish passage

in box culverts


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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


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Ongoing challenges


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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.

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For more information: Louise Dutton 4045 7320

Documents

Balancing fish passage with hydraulic and cost efficiency