Preliminary Design of Tully Heads Seawall - Option ......2015/07/09 · Table 3-6 Peak inundation...

Tully Heads and Hull Heads Seawall Renewal Project

Preliminary Design of Tully Heads Seawall - Option Assessment Report

Cassowary Coast Regional Council

4 June 2015

Revision: 1

Reference: 243333

Project 243333 File OptionAssessmentReport.docx 4 June 2015 Revision 1

Tully Heads and Hull Heads Seawall Renewal Project

Date 4 June 2015

Reference 243333

Revision 1

Aurecon Australasia Pty Ltd

ABN 54 005 139 873

Level 1, 242 Mulgrave Road Cairns QLD 4870

PO Box 7625 Cairns QLD 4870 Australia

T

F

E

W

+61 7 4019 6400

+61 7 4051 2540

[email protected]

aurecongroup.com

Project 243333 File OptionAssessmentReport.docx 4 June 2015 Revision 1 Page I Page I

Tully Heads Seawall Background

Tully Heads Seawall includes 2 seawalls on the southern part of Googarra Beach. The southern

seawall is named Seawall 1 and the northern seawall named Seawall 2 as shown on the locality plan

below.

A detailed condition assessment was undertaken for both walls, as presented in Aurecon’s report

“Condition Assessment Report – Tully Heads Seawall”, recommending a series of short term and long

term considerations for management of the assets.

This report is aimed at presenting long term remediation options to address the issues identified in the

aforementioned Condition Assessment report.

Seawall 1

Various options exist to protect coastal foreshores. The selection of the most appropriate option

depends on the site and environmental conditions. Five options are proposed for the protection of

Tully Heads Foreshore. Indicative costs (exclusive of GST) associated with the construction of those

options are also estimated.

Option 1 – Rock armoured revetment

Variant A – Toe buried underneath beach surface - approx. $4,200,000

Variant B – Toe on existing beach surface - approx. $2,550,000

Variant C – New rock revetment - approx. $6,620,000

Option 2 – Geocontainer revetment - approx. $10,300,000

Option 3 – Reinforced concrete seawall - approx. $26,100,000

A Multi Criteria Analysis has been undertaken to compare the mentioned options above. These

options are evaluated against criteria such as impact, effectiveness, social value, government process

and economics. Following this analysis, the rock revetment repair with buried toe is found to be the

Executive summary

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best suited for Seawall 1 at Tully Heads, provided that sufficient armour stone can be procured

economically. These proposed works are however subject to relevant stakeholder feedback.

Ultimate replacement/upgrade of the seawall will trigger the requirement to obtain new development

approvals to support lawful construction of the works. Notwithstanding this, any interim management

works, or works carried out prior to the ultimate replacement should be cognisant of these existing

approvals.

Seawall 2

Seawall 2 is believed to be mostly buried under the existing beach. The rocks that can be seen are

assumed to be the crest rocks. It is assumed that the rest of the seawall structure is complete under

the existing beach. Reconstructing Seawall 2 will imply large excavation and is not considered as

critical works at this time. Regular monitoring inspections are recommended to remediate any scouring

issue or crest damage, especially after storm event.

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Contents Executive summary I

1 Introduction 1

1.1 Purpose 1

1.2 Methodology 1

1.3 Assumptions and limitations 1

2 Review of existing data 2

2.1 Locality and subject site 2

2.2 Land tenure 3

2.3 Project background 4

2.4 Previous studies 4

2.5 Desktop design review 5

2.6 Site conditions 6

3 Design basis 8

3.1 Design considerations 8

3.2 Design risk 10

3.3 Design parameters 11

4 Concept design option assessment 15

4.1 Proposed concept design layout 15

4.2 Seawall 1 upgrade/reconstruction options 15

4.3 Cost estimate of options 22

5 Multi-criteria analysis 26

5.1 Analysis criteria 26

5.2 Option analysis 28

6 Conclusion 30

7 References 31

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Appendices

Appendix A

Document register

Appendix B

Option Assessment Drawings

Appendix C

Approved Plans of Development – existing Seawall 1 and Seawall 2

Figures

Figure 2-1 Locality plan of the existing seawalls at Tully Heads 2 Figure 2-2 Project site land tenure 3 Figure 2-3 Bathymetry in the vicinity of Tully Heads (AUS 829 chart) 7 Figure 4-1 Example of geocontainer seawall 20 Figure 4-2 Example of concrete stepped seawall 21

Tables

Table 2-1 Summary of land tenure within the Project footprint 3 Table 2-2 Tully Heads Seawall chronology 4 Table 2-3 Tidal planes at Clump Point published by Maritime Safety Queensland (MSQ), 2014 6 Table 3-1 Key standards used in seawall design 9 Table 3-2 Risk of encountering various ARI events in 20 and 50 year period 10 Table 3-3 Wind speed conversion from m/s to km/h and knots 11 Table 3-4 Extreme wind recurrences at Tully Heads (10 m above sea level) 11 Table 3-5 Storm tide levels at Tully Heads (including wave set-up) from JCU 12 Table 3-6 Peak inundation levels at Tully / Hull Heads from the Cardwell Inundation Study project 12 Table 3-7 Design water levels 13 Table 3-8 Earthquake parameters for Tully Heads 14 Table 4-1 Indicative material quantity associated with Option1 - Variant A 17 Table 4-2 Indicative material quantity associated with Option 1 - Variant B 18 Table 4-3 Indicative material quantity associated with Option 1 - Variant C 19 Table 4-4 Indicative material quantity associated with Option 2 20 Table 4-5 Material quantity associated with Option 3 22 Table 4-6 Assumed material rates 23 Table 4-7 Proposed contingencies 23 Table 4-8 Indicative cost estimate for Option 1 – Variant A 24 Table 4-9 Indicative cost estimate for Option 1 – Variant B 24 Table 4-10 Indicative cost estimate for Option 1 – Variant C 24 Table 4-11 Indicative cost estimate for Option 2 25 Table 4-12 Indicative cost estimate for Option 3 25 Table 5-1 Multi-criteria analysis 29

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Acronyms and abbreviations

Abbreviation Explanation

ACH Act Aboriginal Cultural Heritage Act 2003

AHD Australian Height Datum

BCA Building Code of Australia

CCRC Cassowary Coast Regional Council

CHMP Cultural Heritage Management Plan

CMD Coastal Management District

D50 Median grain diameter

DAFF Department of Agriculture, Fisheries and Forestry

DEHP Department of Environment and Heritage Protection

DNRM Department of Natural Resources and Mines

DoE Department of the Environment

EIS Environmental Impact Statement

EPBC Act Environment Protection and Biodiversity Conservation Act 1999

FHA Fish Habitat Area

GPS Global Positioning System

GBRMPA Great Barrier Reef Marine Park Authority

GBRMP Act Great Barrier Reef Marine Park Act 1975

HAT Highest Astronomical Tide

IDAS Integrated Development Assessment System

LAT Lowest Astronomical Tide

MCA Multi-Criteria Analysis

MGA Map Grid of Australia

MHWS Mean High Water Springs

MHWN Mean High Water Neaps

MLWN Mean Low Water Neaps

MLWS Mean Low Water Springs

MSL Mean Sea Level

NDDRA Natural Disaster Relief and Recovery Arrangements

NES National Environmental Significance

SEMP Shoreline Erosion Management Plan

SPA Sustainable Planning Act 2009

SP Reg Sustainable Planning Regulation

TC Tropical Cyclone

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Glossary

Term Definition

Wave overtopping Wave overtopping of seawalls is caused by the direct (and often violent) impact of waves on a structure, which can result in structural damage. More importantly, the water discharged above the structure crest constitutes a hazard to not only the crest itself, but also to people and infrastructure located directly behind the seawall.

Overtopping can also cause saturation of the soil profile, increasing pore water pressure and the chance of failure from sliding, overturning or removal of retained soil.

Sea level rise Sea level rise is defined by an increase of the mean water level due to an increase of greenhouse gases in the atmosphere.

Storm surge A storm surge is a rise in water level due to an offshore low pressure system such as a cyclone.

Wave set-up

After incoming waves break, the average level of the water inside the surf zone to the beach is set up higher than the sea level offshore from the breaker zone

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1.1 Purpose Aurecon has been commissioned by Cassowary Coast Regional Council (CCRC) to complete Stage 1

of a preliminary design required for the replacement, extension and modification of the existing

seawalls at Tully Heads and Hull Heads. Stage 1 includes the development of risk management

solutions to manage both Tully Heads and Hull Heads seawalls in their existing conditions. Moreover

Stage 1 incorporates the review of permits and approvals for both seawalls and the preparation of a

preliminary design for the Tully Heads Seawall.

Tully Heads Seawall is an erosion protection structure but is not a flood control structure. Aurecon has

issued a condition assessment report for both Hull Heads and Tully Heads Seawall including risk

management solutions and review of existing permits and approvals.

This option assessment report is part of the preliminary design phase relating to the Tully Heads

seawall. An Environmental Design Report (EDR) has been prepared concurrently for this site.

1.2 Methodology In preparing this option assessment report for the Tully Heads seawall, it was necessary to:

Complete a desktop review of all existing information pertaining to the Tully Heads seawalls, including previous designs, regulatory approvals, studies and investigations

Establish design criteria associated with the seawall design

Undertake an option assessment of five coastal revetment options

Carry out a multi-criteria analysis to identify a preferred option

Once relevant stakeholders have reviewed and indicated any comments on this report, a

recommended option may be selected and detailed in the recommendation report.

1.3 Assumptions and limitations The following assumptions and limitations apply to this study:

The review and assessment undertaken, with respect to past works, design and investigations completed to date in relation to the Tully Heads seawalls has been limited to those documents listed in Appendix A which were provided to Aurecon by CCRC as part of this study.

In undertaking this assessment, Aurecon has made assumptions that the team could reasonably be expected to make in accordance with sound professional practice.

1 Introduction


2.1 Locality and subject site The project site is situated approximately 120 km south of Cairns and 160 km north of Townsville on

the Queensland eastern coast.

Located within the Cassowary Coast Regional Council Local Government area (LGA) (former Cardwell

Shire), Tully Heads seawalls are accessed via Carron Esplanade and Taylor Street. Tully Heads

seawalls are bounded by the coastline to the east and the mouth of the Tully River to the south. The

beach along Tully Heads township is named Googarra Beach. Within the immediate area to the west

are residential properties which form the township of Tully Heads.

The seawalls of interest are located from the southern end of Taylor Street to the junction of Taylor

Street and Carron Esplanade, as shown on Figure 2-1. For the purposes of this report, the larger

seawall located to the south-east of Taylor Street has been referred to as ‘Seawall 1’ and the smaller

seawall located to the north as ‘Seawall 2’.

Figure 2-1 Locality plan of the existing seawalls at Tully Heads

2 Review of existing data


2.2 Land tenure

The Project site is identified as a mixture of State reserve land and local government road reserve. A

summary of the land tenure, noting the parcels of land to which each wall section relates, is provided

in and illustrated in Figure 2-2. It should be noted that ownership details for portions of land other than

road reserve were obtained from the online database, RP Data and not through purchasing formal

Certificates of Title. As such, the information should be treated as preliminary reference only.

Table 2-1 Summary of land tenure within the Project footprint

Lot Plan Tenure Ownership/Lessee Wall Section

Carron Esplanade Local road reserve

State of Queensland (Represented by DNRM) Seawall 1 and Seawall 2

10 CWL802853 Reserve State of Queensland (Represented by DNRM) – Reserve for Local Government Purposes(Camping Park and Recreation)

Seawall 2

Figure 2-2 Project site land tenure


2.3 Project background

Various sections of Tully Heads Seawalls have been constructed, upgraded and repaired since the

1980’s. Table 2-2 summarises a chronology which has been drawn from various reports and

information provided during the Project inception meeting with CCRC.

Table 2-2 Tully Heads Seawall chronology

Date Event Comment

Late 1980s / Early 1990s

Main portion of Seawall 1 constructed by property owners

Constructed without relevant approvals and no design drawings available

Early 1990’s Investigation of Seawall 1 stability and recommendation on upgrade works

Mid 1990’s Upgrade of Seawall 1 (Stage 1- approximately 100 m of upgrade)

Approved under Section 86 of the Harbours Act 1955 on 10 December 1992, design drawings prepared by GHD on behalf of Cardwell Shire Council (refer Appendix F)

Late 1990’s Construction of the southern end of Seawall 1 Approved under Section 86 of the Harbours Act 1955 on 02 December 1996, design drawings prepared by Cardwell Shire Council (refer Appendix F)

2006 Damage to Tully Heads Seawall 1 as a result of Tropical Cyclone Larry in March 2006.

-

2006 Design and approvals of Seawall 2 Approved by EPA permit no: IPCC004199906CV, design drawings prepared by International Coastal Management on behalf of Cardwell Shire Council (refer to Appendix F)

2007 Reconstruction of Seawall 1 No formal design understood to be undertaken as part of these minor works

2009 Shoreline Environmental Management Plan (SEMP) developed by BMT WBM on behalf of CCRC

-

February 2011

Significant damage to both seawalls occurs as a result of Tropical Cyclone Yasi, especially on the upper sections and at the crest.

Displaced rocks were pushed back on the wall by property owners.

2011 Applications submitted to gain funds from the Natural Disaster Relief and Recovery Arrangements (NDRRA) in order to restore the seawalls to appropriate standard.

The applications were rejected on the grounds that the seawalls do not constitute an essential public asset (not seen as protecting a community thoroughfare or esplanade).

2.4 Previous studies

2.4.1 Tully Heads seawall stability investigation –1992

GHD undertook a stability and condition assessment of the original seawall constructed by property

owners. Recommendations and cost estimates of seawall upgrades were provided.

2.4.2 Shoreline erosion management plan (SEMP) - 2009

In 2009, BMT WBM were engaged by CCRC to undertake a review of coastal processes, and the

status of erosion impacts along the Tully Heads to Hull Heads shoreline. Key management measures

were proposed to address the identified impacts to develop a Shoreline Erosion Management Plan

(SEMP) for implementation. In preparing the SEMP, BMT WBM considered the options and feasibility

of engineering works and management actions that could be carried out.


Whilst it is noted that the SEMP was prepared before the Tropical Cyclone Yasi event in 2011, the

report recommended that, in relation to the Tully Heads seawall specifically, that the northern section

of the seawall at the southern end of Taylor Street to an approved and appropriate standard of

defence. It was also recommended taking no action in front of Council reserve, which creates a pocket

beach.

2.4.3 Restoration of Tully Heads and South Mission Beach Seawalls - 2011

J T Smith and Associated Pty Ltd prepared a seawall restoration report detailing the nature and costs

of works required to reconstruct the seawalls along South Mission Beach and Tully Heads following

Tropical Cyclone Yasi. This report was compiled to assist CCRC to plan the reconstruction of the

seawalls.

2.4.4 Post-Yasi cyclone inspection - 2011

GHD undertook a seawall damage assessment following TC Yasi and inspected Tully Heads Seawalls

in April 2011. Most of the observed damage was on the crest of the seawall, where numerous rocks

were displaced onto the Esplanade and private properties. In addition, severe erosion occurred at the

crest. Remediation works were recommended to restore the seawalls. This report was prepared to

support the funding application to NDDRA which was ultimately unsuccessful in securing funding.

2.5 Desktop design review

2.5.1 Seawall 1

Tully Heads Seawall 1 was built over several decades as described in Section 2.3. The existing

seawall, as shown on the Design Drawing 16566-1 dated 17 November 1992 and drawing BP 97.01

dated 13 November 1996 (refer to Appendix C) consists of a filled rock structure, approximately 410 m

in length, with the following details:

Armour rock mass of approximately 3t on top of existing armour (from the private owners’ construction)

1v:2h slope

Crest level at 3.5 m AHD and toe at approximately 0.5 m below AHD.

It is noted that the seawall was reconstructed and reshaped following storm events, in particular

following TC Larry and TC Yasi.

2.5.2 Seawall 2

Tully Heads Seawall 2 was designed and approved in 2006 as a partially buried two layer rock

seawall, approximately 160 m in length, with the following attributes:

Primary armour rock mass of 1t to 2t

Slope no steeper than 1v:1.5h

Crest level at 3.7 m AHD and toe at approximately -2.36 m AHD

Similarly to Seawall 1, Seawall 2 was reshaped following TC Yasi.


2.6 Site conditions

2.6.1 Tides

Maritime Safety Queensland (MSQ) doesn’t provide tidal planes at Tully Heads. However tidal planes

are published at Clump Point (approximately 20km north from the site). CCRC indicated that

information on tidal variance along the Cassowary Coast is provided in the Innisfail – Mission Beach

Storm Tide Study, Final Report, June 2009, GHD. A ratio of 1.080 and 1.088 is recommended to be

applied to the Mourilyan Harbour tidal planes to determine the tidal planes at Clump Point and Tully

Heads respectively. Since the variance in ratio between Clump Point and Tully Heads is minor, the

tidal planes at Clump Point have been used as tidal reference for this assessment. Table 2-3

summarises the tidal planes at Clump Point.

Table 2-3 Tidal planes at Clump Point published by Maritime Safety Queensland (MSQ), 2014

Tide Level (m to AHD)

Highest Astronomical Tide (HAT) 1.94

Mean High Water Springs (MHWS) 1.04

Mean High Water Neaps (MHWN) 0.33

Mean Sea Level (MSL) 0.05

Australian Height Datum (AHD) 0.00

Mean Low Water Neaps (MLWN) -0.19

Mean Low Water Springs (MLWS) -0.89

Lowest Astronomical Tide (LAT) -1.68

2.6.2 Bathymetry

Figure 2-3 indicates an approximate bathymetry in the vicinity of Tully Heads, sourced from the marine

chart AUS 829 – Brook Islands to Russell Island. Depths are referenced to Chart Datum,

approximately Indian Spring Low Water level (which is close to LAT).


Figure 2-3 Bathymetry in the vicinity of Tully Heads (AUS 829 chart)

It is understood that no bathymetric or topographic survey is available. Ground level data surveyed

during the existing seawall condition assessment at Tully Heads will be included in the concept

design.

2.6.3 Geotechnical conditions

No geotechnical information is available at the site. Laboratory testing of beach and dune material, as

part of a geotechnical investigation, would be recommended should CCRC progress investigations to

undertake the detailed design of a complete repair/replacement of the seawall.


3.1 Design considerations

3.1.1 Seawall functionality

The design of the seawall is driven by the following functional requirements:

Protect Carron Esplanade and adjacent residential properties from shoreline erosion;

Have reduced environmental and visual impact.

The seawall design purpose is to mitigate shoreline erosion along Carron Esplanade. It is important to

note that the seawall is not a flood control structure. During an extreme weather event, the area

behind the seawall (including Carron Esplanade and the private properties located behind) may be

inundated and damaged due to seawater flooding. It will be unsafe for pedestrian or vehicles to stand

behind the seawall at times. However, the seawall structure will protect the shoreline from ongoing

erosion threat during the design weather conditions.

The seawall is not designed to be a pedestrian access therefore is not suitable for pedestrians to

cross the structure. Warning signs, fencing, access points and other measures are recommended to

discourage the public from crossing the seawall.

3.1.2 Statutory requirements

The design work shall comply with the requirements of the following:

Acts of the Commonwealth of Australia

Statutory Laws and Regulations of the State of Queensland (QLD), Australia

Work Health and Safety Regulation 2011

Great Barrier Reef Marine Park Act, 1975

Environment Protection and Biodiversity Conservation Act (EPBC Act)

Relevant Commonwealth and State legislation (Acts and regulations)

Integrated Development Assessment System (IDAS) Code for Prescribed Tidal Work – Schedule 4A of the Coastal Protection and Management Regulation 2003

Relevant provisions of the Cardwell Shire Planning Scheme 2007 as called up by the Schedule 4A code

Consideration of any proposed new provisions under the Draft Cassowary Coast Regional Council Planning Scheme 2014

3 Design basis


Any relevant provisions of the State Development Assessment Provisions (SDAP) State Code and State Planning Policy

Far North Queensland Regional Organisation of Councils (FNQROC) Development Manual

Any other authority having jurisdiction over the site

Regarding public access, there is no standard that provide requirements for pedestrian access

associated with a seawall construction. However the State Development Assessment Provisions

(SDAP) Code for Tidal Works makes reference to public access in Performance Outcome (PO) 10,

with the following conditions:

AO10.1 Development adjacent to state coastal land or tidal water:

(1) demonstrates that restrictions to public access are necessary for:

(a) the safe or secure operation of development, or

(b) the maintenance of coastal landforms and coastal habitat

(2) separates residential, tourist and retail development from tidal water with public areas or public access facilities, or

(3) maintains existing public access (including public access infrastructure that is in the public interest) through the site to the foreshore for:

(c) pedestrians, via access points including approved walking tracks, boardwalks and viewing platforms, or

(d) vehicles, via access points including approved roads or tracks.

AO10.2 Development adjacent to state coastal land, including land under tidal water: (1) is located and designed to:

(a) allow safe and unimpeded access to, over, under or around built structures located on, over or along the foreshore

(b) ensure emergency vehicles can access the area near the development, or

(2) minimises and offsets any loss of access to and along the foreshore within two kilometres of the existing access points, and the access is located and designed to be consistent with (1)(a) and (b).

3.1.3 Design standards

Table 3-1 highlights the design documents and Australian Standards relevant to the Project that may

be relevant to the concept design of Tully Heads seawall.

Table 3-1 Key standards used in seawall design

Key Standards and Usage

Designation Title Typical Usage

AS 1000 The International System of Units (SI) and its application

Units to be used on the Project.

AS 1170 (Parts 0 to 4) Minimum design loads on structures (SAA Loading Code – Australian Standard)

General loadings including wind load and earthquake loads

Load combinations

AS 4997 Guidelines for the Design of Maritime Structures

General Design Requirements

Design Loads

Load combinations


Key Standards and Usage

Designation Title Typical Usage

AS 3600 Concrete Structures Design of concrete elements

AS 4678 Earth Retaining Structures Design of soil retaining structure

AS 3962 Guidelines for Design of Marinas Design of walkways, stairway and boat ramp

AS 1657 Fixed platforms, walkways, stairways and ladders – Design, construction and installation

Design of walkways and stairway

BS 6349 (Part 1 & 7) British Standard Code of Practice for Maritime Structures

Design wave loadings

Design of revetment

CEM (2006) Coastal Engineering Manual (USACE)

Design of seawall and rock armour unit

Rock Manual (2007) The Rock Manual. The Use of Rock in Hydraulic Engineering (2nd Edition)

Design of seawall and rock armour unit

SPM (1988) Shore Protection Manual (USACE) Design of seawall and design wave criteria

Coastal Engineering Guidelines for working with the Australian coast in an ecologically sustainable way

Coastal Engineering Guidelines for working with the Australian coast in an ecologically sustainable way, Engineers Australia, 2012

Design of coastal structures

3.2 Design risk According to “Coastal Engineering Guidelines for working with the Australian coast in an ecologically

sustainable way” (Engineers Australia 2012), there is approximately a 39% risk of encountering a 100

year ARI event in a 50 year period. Table 3-2 indicates the risk to encounter a 50, 100, 500 and 1,000

year ARI event in a 20 and 50 year period.

Table 3-2 Risk of encountering various ARI events in 20 and 50 year period

Average Recurrence Interval (ARI) 50 year 100 year 500 year 1,000 year

Annual Exceedance Probability (AEP) 2% 1% 0.2% 0.1%

Probability of encounter over 20 years 33% 18% 4% 2%

Probability of encounter over 50 years 63% 39% 10% 5%

The primary action on the seawall is wave impacts that affect:

Structural strength, undermining and stability of the revetment

Inundation risk due to overtopping (during extreme storms)

Changes to the surrounding environment (e.g. scour in front of and erosion at either end of the wall or

at the crest) may be ongoing over the design life of the seawall. This will involve ongoing maintenance

costs. Additional seawall and beach material may be required in the design life of the revetment.

CCRC should set a maintenance budget to carry out required repairs and monitoring investigations.


3.3 Design parameters

3.3.1 Design life and design event

According to the Department of Environment and Heritage Protection (DEHP) building and

engineering standards for tidal works operational policy, the minimum development standard for a

seawall is a 50 year ARI design standard for a design life of 50 years.

It is proposed to follow this recommendation for the Tully Heads Seawall.

3.3.2 Design wind

Winds play a dominant role in wave generation. While the ambient wind climate at Tully Heads is mild,

high wind speeds occur when storms and cyclones are in the vicinity of the area. Wind speeds are

mainly reported in m/s in this study. Table 3-3 indicates the conversion of m/s to km/h and knots.

Table 3-3 Wind speed conversion from m/s to km/h and knots

Wind speed in m/s Wind speed in km/h Wind speed in knots

5 18 9.7

10 36 19.4

15 54 29.2

20 72 38.9

25 90 48.6

30 108 58.3

35 126 68.0

40 144 77.8

Structural design wind conditions are given in from the AS/NZS 1170.2 standard. This wind code gives

3-second wind gust measured at 10 m above ground for all Australian regions. Tully Heads lies in

Cyclonic Region C. The Coastal Engineering Manual (CEM) Part II, Chapter 2, Figure II-2-1

relationship between a 3-second wind speed and an hourly averaged wind speed based on a large

sample of wind measurements 10 m above sea level was adopted to derive hourly winds. Table 3-4

presents the 3-second and hourly averaged wind speeds for a range of Average Recurrence Interval

(ARI) events for a Region C location.

Table 3-4 Extreme wind recurrences at Tully Heads (10 m above sea level)

Average Recurrence Interval (year)

3s gust wind (m/s)

Hourly wind (m/s)

1 23.0 15.5

5 33.0 22.0

10 39.0 26.0

20 45.0 30.0

50 52.0 34.7

100 56.0 37.3

200 61.0 40.7

500 66.0 44.0

1000 70.0 46.7

Those wind speeds would be used in the detailed design phase for any wave modelling and to design

structural elements affected by wind.


3.3.3 Design water levels

3.3.3.1 Sea level rise

According to the DEHP building and engineering standards for tidal works operational policy, it is

recommended allowing a minimum of 0.3m to take sea level rise into account in a seawall

development.

3.3.3.2 Storm tide level

Storm surge is an increase in water elevation due to the influence of wind shear (wind set-up) and

decreased atmospheric pressure associated with low weather systems such as tropical depressions

and cyclones. Storm tide is the combination of tide and storm surge. The extreme shoreline water

level includes both storm tide and wave set-up (due to breaking waves).

A comprehensive Monte Carlo storm tide model study was undertaken in 2004 by James Cook

University (JCU) for the Queensland East Coast region looking at the combined probability of

exceedance of storm surge and tide. This study proposed storm tide levels for extreme cyclonic events

at various locations, based on offshore cyclonic modelling. Table 3-5 indicates the extreme shoreline

water levels, inclusive of wave set-up, in the vicinity of Tully Heads for various extreme events

Average Recurrence Intervals (ARI) provided by the JCU study.

Table 3-5 Storm tide levels at Tully Heads (including wave set-up) from JCU

Average Recurrence Interval (ARI)

50 year 100 year 500 year

2004 storm tide level 2.02 m AHD 2.13 m AHD 2.66 m AHD

2064 storm tide level(*) 2.35 m AHD 2.46 m AHD 2.95 m AHD

(*) based on the 2004 JCU study - Greenhouse scenario, including 0.3m of sea level rise

In addition, BMT WBM carried out a coastal inundation investigation in 2007 during the Cardwell

Inundation Study project focusing on Tully and Hull Heads area. Table 3-6 provides peak inundation

levels for return period events greater than 100 year ARI assessed by BMT WBM.

Table 3-6 Peak inundation levels at Tully / Hull Heads from the Cardwell Inundation Study project


100 year 200 year 500 year

Peak inundation levels (including wave set-up)

2.70 m AHD 3.17 m AHD 3.79 m AHD

By extrapolation, a 50 year ARI peak inundation level is approximately 2.25 m AHD. It is understood

that no sea level rise or climate change effects were considered in the peak inundation levels given in

Table 3-6.

The Cardwell Inundation Study levels have been derived locally and seem slightly higher than the JCU

numbers. A storm tide level of 2.25 m AHD will be taken as the 50 year ARI design storm tide level for

the project.


3.3.3.3 Design water levels

Table 3-7 displays the total water level that will be considered in the design of the seawall elements

(includes sea level rise and wave set-up).

Table 3-7 Design water levels


50 year

Storm tide level (m AHD) 2.25

Sea level rise (m) 0.3

Total water level (m AHD) 2.55

3.3.4 Design waves

Ambient waves in the region are typically short period wind-waves generated from local winds blowing

across the fetch between the Great Barrier Reef and the site. According to the Tully Heads to Hull

Heads Shoreline Erosion Management Plan (SEMP) (BMT WBM, 2009), most ambient waves come

from the ESE direction and significant wave heights are less than 1m most of the time.

Extreme offshore significant wave heights are indicated in the SEMP for events greater than 100 year

ARI events and are not available for a 50 year ARI event.

To define a significant wave height in front of the seawall that may be used to design the seawall

elements, a depth-limited wave estimate was carried out.

From the SEMP storm erosion assessment, it is noted that the beach profile would be similar prior and

post storm around -1 m AHD. Therefore the water depth at -1 m AHD (located approximately 60 – 80m

of the existing seawall) was considered in the depth-limited wave assessment. Considering a water

level at 2.55 m AHD, a 50 year ARI significant wave height is estimated at approximately 2.75 m. This

significant wave height will be considered for the concept design phase. However it is recommended

undertaking wave modelling to support the determination of design waves for the detailed design

phase of the project.

Approximate peak period for a 50 year RI event would be in the range of 5 s to 7 s and this would

need to be confirmed during the wave modelling in the detailed design phase.

3.3.5 Design overtopping

There is no specific standard provision for overtopping rate for seawalls as these structures are not

designed to mitigate both erosion and flooding.

When constructing erosion protection revetments, the averaged overtopping discharges generally

dictate the revetment crest levels. Average overtopping rates may be assessed with the Eurotop

(2008) “Overtopping Manual”, the Coastal Engineering Manual and the online Overtopping Neural

Network (Deltares). Average overtopping rates acceptable to prevent damage to paved surface behind

a seawall are generally lower than 200 L/s/m. Yet those overtopping rates along the revetment crest

would be unsafe for pedestrians and vehicles. It is also important to note that individual wave

overtopping flows may be up to 100 times larger than the average overtopping rate. Moreover it is

noted that overtopping estimates are only used to provide an order of magnitude estimates and are

not precise estimates. If accurate estimates are required, site specific physical modelling is needed.


3.3.6 Long term beach erosion

Tully Heads to Hull Heads Shoreline Erosion Management Plan (SEMP), 2007, states that the area

has experienced periods of considerable erosion but that were followed by periods of accretion. This

document also mentions that there is no evidence that the coastal system has experienced persistent

sediment volume losses or progressive erosion.

3.3.7 Longshore sediment transport

The SEMP reported that the total annual longshore sand transport potential along Googarra Beach is

in the order of 25,000 and 30,000 m3 per year. The net sediment transport is small and on average

northwards. However the magnitude and direction of the net longshore sediment transport is not

constant through the year. In addition, cyclonic events may have a significant influence on the

magnitude of the net longshore sediment transport.

3.3.8 Sediment characterisation

From a visual assessment of beach material, it is noted that well sorted (uniform grain sizes) medium

sand (approx. D50 350 – 500 μm) is characteristic of Googarra Beach in front of Tully Heads existing

seawall.

3.3.9 Design scour level

According to the DEHP building and engineering standards for tidal works operational policy, the toe

of the seawall must be designed to accommodate potential long term erosion for at least 50 years and

the toe of the seawall needs to be located, as a minimum, at or lower than LAT.

Since the SEMP didn’t report any long term erosion trend, it is proposed to design the toe of the

seawall at LAT and to include a collapsible toe in front of the seawall. Maintenance might be required

over the life of the seawall to mitigate any scour that may appear overtime.

3.3.10 Tidal currents

No data is available regarding tidal currents in the area however it is not anticipated that tidal effects

will be significant. In addition, the seawall elements (i.e. rock, concrete unit, geotextile bags etc)

dimension will most likely be greater than what would be required to withstand tidal effects.

3.3.11 Density of seawater

The density of seawater will be adopted as 1026 kg/m3 (as per AS 4997).

3.3.12 Seismic condition

According to AS 1170.0-2002 and AS1170.4-2007, the earthquake return period of 500 years (1/500)

shall be applied for a marine structure with an importance level of 2 and a design life of 50 years.

Table 3-8 summarises earthquake parameters at the site assumed for the design.

Table 3-8 Earthquake parameters for Tully Heads

Earthquake Parameters (in general accordance with AS1170.0-2002 and AS1170.4-2007)

Annual probability of exceedance 1/500

Hazard Coefficient 0.07

Structural Importance factor 2

Ductility factor 1

Structural performance factor 0.77


4.1 Proposed concept design layout In 2009, the SEMP recommended upgrading the northern section of Tully Heads existing seawall

(seawall 1) but that no action is taken in front of Council’s Reserve, indicating that a pocket beach

would create between the two seawalls. It is proposed to follow the SEMP recommendation in this

concept design phase. The proposed works extent is presented in Drawing LA-002 in Appendix B.

4.1.1 Seawall 1

Seawall 1 is approximately 400m long and has been damaged during past severe storm events. It is

proposed to upgrade or replace Seawall 1. Conceptual options for this work are presented in the

following sections.

4.1.2 Seawall 2

Seawall 2 is believed to be mostly buried under the existing beach. The rocks that can be seen are

assumed to be the crest rocks. Those crest rocks have been displaced following storm and cyclone

events. It is proposed to relocate those rocks in an orderly manner and to add large 6,000kg rocks as

well to increase the crest stability. However it is assumed that the rest of the seawall structure is

complete under the existing beach. Therefore no other works is considered in this option assessment

report regarding Seawall 2. Reconstructing Seawall 2 will imply large excavation and is not considered

as critical works. Regular monitoring inspections are recommended to remediate any scouring issue or

crest damage, especially after storm event.

4.2 Seawall 1 upgrade/reconstruction options Various options exist to protect coastal foreshores. The selection of the most appropriate option

depends on the site and environmental conditions. Five options are proposed for the protection of

Tully Heads Foreshore.

Option 1 – Rock armoured revetment

Variant A – Toe buried underneath beach surface

Variant B – Toe on existing beach surface

Variant C – New rock revetment

Option 2 – Geocontainer revetment

Option 3 – Reinforced concrete seawall

4 Concept design option assessment


Other options such as irregular and regular concrete blocks, Seabees, masonry seawall, terraced

concrete blocks, timber and steel sheetpiles are other revetment options that have not be looked into

as they are not considered suitable for the site.

The following assumptions were made in the option assessment and material quantity estimate

described in the following sections:

No detailed survey was undertaken to obtain the dimensions of the existing seawall, therefore the actual volume of material required may increase once the detailed design and a survey is carried out.

It is assumed that the toe of the existing seawall is buried

No geotechnical information was available at the time of writing. A detailed geotechnical investigation will be required to confirm the selected option feasibility and details.

The concept design options are designed to a 50 year ARI event and would be damaged in severe weather events that would be similar to TC Yasi.

The seawall is not intended for pedestrian access. However consideration should be given to inclusion of a Building Code of Australia (BCA) compliant public access stair to provide a safe access to the beach, or alternate means of deterring unauthorised access on the wall. Such measures have been excluded from the quantity estimate but a unit cost has been included in the contingency table.

Warning signs, fencing and other public safety features have not been detailed in this assessment but are recommended to be implemented in the detailed design phase

Regular monitoring and maintenance is critical with any type of coastal protection revetment

4.2.1 Option 1 - Rock revetment

A conventional double layer rock armour seawall is generally the most economical and robust solution

if an appropriate rock quarry, able to produce the required rock sizes, is available near the site.

Advantages of a rock revetment include:

High degree of coastal protection

Durable structure with little maintenance

Adaptable revetment to beach erosion and sea level rise

Relatively cost-effective if material is available

Easily repaired, if damaged during a storm event

Reduced overtopping due to porosity of the slope

Disadvantages of a rock structure include:

Potential community concerns over visual amenity (although as the existing seawall is a rock structure, this may be minimal)

Reduction of beach or foreshore space – a sloping wall reduces foreshore space

Beach access restricted to stairways – the top of seawall should be fenced off for safety reasons

Additional environmental impacts relating to rock quarry


4.2.1.1 Variant A - Rock revetment repair with buried toe

This option consists of reusing the existing rock armour as secondary armour and adding a primary

layer of armour rock on a 1v:1.5h slope with a buried toe. A cross-section is presented on Drawing LA-

003 in Appendix B.

Structure shape

The existing rock armour shall be shaped to form a layer of at least 1m thick. Any gaps in the armour

shall be filled. A minimum 2.1 m thick armour layer of rocks of M50=3,000 kg shall be installed once the

layer of existing rocks is shaped.

To limit average overtopping rates lower than 200 L/s/m in the design event for a 50 year period, a

crest at 4m AHD is suitable. This is approximately 0.5 m higher than the existing foreshore level. It is

understood that Tully Heads community desires keeping the visual aspect of the current foreshore. A

crest at 3.5m AHD would be suitable for current climatic conditions but would eventually have to be

raised when sea level rises. It is proposed to increase the seawall height at a later date, therefore

keeping the current visual amenity at this stage.

The toe of the rock revetment shall be buried to LAT to mitigate scour issues. This assumes that the

existing seawall is also buried. This will have to be confirmed from a survey carried out to identify any

buried material at the site. Secondary armour rocks of M50=300 kg will have to be added to construct

the toe. The seawall toe will require monitoring and additional stones may be required to maintain the

seawall if and when scour develops.

Quantity estimate

Table 4-1 presents an indicative quantity estimate of material associated with this option.

Table 4-1 Indicative material quantity associated with Option1 - Variant A

Material type Unit Approximate quantity

Excavation/backfill m3 4,500

Primary and crest armour t 25,000

Secondary armour (toe) t 3,000

This quantity estimate excludes any additional material that may be required to repair and reshape the

existing rock layer.

Conclusion

The main advantages of the rock revetment upgrade with buried toe are:

Scour mitigation

No demolition of the existing seawall

The principal disadvantages associated with this option are:

Reuse of existing material (potentially of lower quality)

Geotextile layer presence unknown

4.2.1.2 Variant B - Rock revetment repair with toe on existing surface

This option is similar to Variant A and reuses the existing rock armour as secondary armour. An

additional primary rock armour layer is added and the toe is formed on the existing beach. A cross-

section is presented on Drawing LA-003 in Appendix B.


Structure shape

The existing rock armour shall be shaped to form a layer of at least 1 m thick. Any gaps in the armour

shall be filled. A minimum 2.1 m thick armour layer of rocks of M50=3,000 kg shall be installed once the

layer of existing rocks is shaped.







The toe of the rock revetment of this option shall be placed on the existing beach surface. Such a toe

may be subject to scour during larger wave events. The rocks placed on the seabed act as a sacrificial

apron but regular monitoring would be required to investigate any scouring issues. This toe shape

triggers a loss of beach space for recreational use.

Quantity estimate


Table 4-2 Indicative material quantity associated with Option 1 - Variant B



Secondary armour (toe) t 3,000

This quantity estimate excludes any additional material that may be required to repair and reshape the

existing rock layer.

Conclusion

The main advantages of the rock revetment upgrade with a toe on the existing surface are:

Limited excavation

No demolition of the existing seawall


Reuse of existing material (potentially of lower quality)

Geotextile layer presence unknown

Potential scour issues and increase in monitoring exercises

Loss of beach area

4.2.1.3 Variant C – Total rock revetment reconstruction

This option consists of demolishing the existing seawall and constructing a new seawall with new rock

material and a geotextile layer. A cross-section is presented on Drawing LA-003 in Appendix B.

Structure shape

The existing rock armour shall be demolished and a new profile of 1v:1.5h prepared. A geotextile

equivalent to 600R Elcomax geotextile shall be laid on the shaped profile. A secondary layer of

M50=300kg rock and a primary layer of rocks of M50=3,000kg shall be placed on the geotextile layer.








The toe of the rock revetment shall be buried to LAT to mitigate scour issues. The seawall toe will still

require monitoring and additional stones may be required to maintain the seawall if and when scour

develops.

Quantity estimate


Table 4-3 Indicative material quantity associated with Option 1 - Variant C




Secondary armour t 11,500

Geotextile m2 7,500

Conclusion

The main advantages of the total rock revetment reconstruction are:

Complete reconstruction of the seawall to current design standards

Scour mitigation


Demolition of the existing structure

4.2.2 Option 2 - Sand filled geotextile bags

An alternative sloping seawall option to the rock armoured seawall is a wall comprised of geocontainer

sandbags. This option consists of demolishing the existing seawall and constructing a new seawall

consisting of geocontainers (e.g. Elcorock) with the toe of the seawall being buried in the existing

seabed level. A cross-section is presented on Drawing LA-004 in Appendix B.

A geocontainer seawall can be used in less severe wave climates with design wave heights typically

less than 2m. The design wave height criterion is greater than 2m at the site. However, compared to

other options, the geocontainer wall provides better visual amenity and improved beach access as the

community can walk down and over the geocontainers.

The geocontainer seawall advantages include:

Relatively cost-effective, particularly if the sand is sourced from local beaches

Beach access friendly – the smooth, sloping wall would not require hand railing and may enable direct access to the beach

Adaptable to beach erosion and sea level rise

Limited trucking requirement if the sand can be sourced from the local beach(es)

Re-useable construction material, except geocontainers

The geocontainer seawall disadvantages include:


Durability – bags with constant UV exposure can typically deteriorate within 20 years, and would not meet the design life of 50 years

Reduction of beach or foreshore space – sloping wall reduces flat foreshore space

Vandalism potential – cutting of bags by vandals

Reduced erosion protection compared to the rock revetment in higher wave climate

Less repairable as compared to rock revetment

Higher overtopping due to smooth surface and less porosity

Figure 4-1 Example of geocontainer seawall

4.2.2.1 Structure shape

The geocontainer seawall design would require a double layer of 2.5 m3 geocontainer bags to

withstand the design wave with minimal damage. A slope of 1v:1.5h is proposed and a geotextile layer

would be required between the sloped profile and the geocontainer bags. A reinforced concrete wave

deflector structure is proposed at the crest, to mitigate overtopping damage to the seawall crest. This

structure would reduce the risk of overtopping failure and associated erosion immediately behind the

seawall.

The toe of the wall shall be buried to LAT to mitigate scour issues. The seawall toe will require

monitoring and additional material may be required to maintain the seawall if and when scour

develops.

4.2.2.2 Quantity estimate


Table 4-4 Indicative material quantity associated with Option 2



Geocontainers unit 4,100

Geotextile m2 9,200

Reinforced concrete m3 1,000

4.2.2.3 Conclusion

The main advantages of the geocontainer seawall are:


Visually and pedestrian friendly

Scour mitigation

Easily removed (bags can be cut open and the sand distributed on the beach)



Not appropriate for higher wave climate – containers will have to be replaced during the seawall design life

Not as robust as a rock structure

4.2.3 Option 3 - Reinforced concrete stepped seawall

This option consists of demolishing the existing rock structure and constructing a concrete stepped

seawall along Tully Heads foreshore. A cross-section is presented on Drawing LA-004 in Appendix B.

The advantages of this type of revetment include:

High degree of coastal protection

Low maintenance

Less quantity of material required for construction

Re-usable construction material (after processing)

The disadvantages of this type of revetment include:

Reflection of large portion of the wave energy due to low porosity of the structure which may cause reduction in beach amenity

More expensive as compared to rock armoured revetment

Beach access restricted to stairways - the top of seawall should be fenced off for safety reasons

More difficult to repair as compared to rock revetment, if damage occurs during a storm event

Stability of this type of construction is sensitive to toe erosion (toe sheetpiling may be required for Tully Heads site conditions)

Figure 4-2 Example of concrete stepped seawall

4.2.3.1 Structure shape

The seawall is a stepped gravity earth retaining structure which is attached to a precast toe. The upper

stepped portion of the cross-section is cast in-situ reinforced concrete. Typically the seawall has


380mm rises to 710mm goings. Engineered fill and moisture barrier would be required to support the

seawall.

Heavy overtopping can cause the seawall rear side to scour and the backfill to lose resistance. A layer

of rocks is proposed to be installed behind the seawall crest. This rock layer will assist in maintaining

the soil at the back of the seawall and will mitigate any piping or scouring issue that may occur at the

back of the seawall crest due to potential seawater inundation. The concrete stepped seawall can be

raised in the future, if sea level rises and seawater inundation becomes permanent. An additional

reinforced concrete barrier can be cast on top of the existing crest and tied in using stainless steel

bars. This would require some preparation to the existing concrete surface and include core drilling

and chemical anchoring to set the stainless bars into place.

It is proposed to construct the toe of the seawall at LAT. The toe will consist of precast concrete units

and large rocks that will mitigate any potential scouring issue that may occur. Monitoring should still be

implemented to identify any scour issues that may occur.

4.2.3.2 Quantity estimate


Table 4-5 Material quantity associated with Option 3



Reinforced concrete t 6,500

Moisture barrier m2 4,000

Armour rock t 6,500

4.2.3.3 Conclusion

The main advantages of the concrete stepped seawall are:

Scour mitigation



Wave reflection

4.3 Cost estimate of options The following assumptions were made in the cost estimate

Estimate is preliminary only, and requires confirmation from Council’s preferred suppliers.

Detailed site survey (including buried material) and geotechnical investigation would also be required to confirm estimated quantities.

Assumed rates are assumed to be supply/install but are exclusive of GST

4.3.1 Assumed rates

Table 4-6 indicates the units rates assumed for the materials.


Table 4-6 Assumed material rates

Material type Unit Assumed rates

Excavation/backfill m3 $50

Crest and primary armour t $70

Secondary armour t $65

Reinforced concrete m3 $2,000

Geotextile m2 $35

Geocontainers (Vandal deterrent) unit $600

Moisture barrier m2 $60

4.3.2 Contingencies

Table 4-7 indicates contingencies proposed for the project.

Table 4-7 Proposed contingencies

Contingency and fees Typical range Proposed value

Contractor overheads [+5%, +30%], +15%

Contractor mobilisation and demobilisation [$30,000-$150,000] $100,000

Quarry risk (applicable to quarry material only) [0, +100%] +30%

Weather and program risk [0, +100%] +5%

Geotechnical risk (Acid Sulphate Soil, loose material)

[0, +30%] +10%

Escalation during detailed design (*) [-30% to +30%] +10%

Engineering, procurement, construction management

[+5%, +15%] +10%

Furniture / railing [$2,000, $10,000] $7,000

Pedestrian access stairs [$10,000, $40,000] $20,000

Tree clearing [$30,000, $60,000] $50,000

Re-vegetation [$20,000, $100,000] $50,000

Fees and surveys N/A $50,000

(*) Detailed design escalation covers features which may become required during the consultation and

detailed design process.

A risk assessment is recommended to be developed at the onset of the detailed design phase to

reduce the range of uncertainties on these contingencies.


4.3.3 Indicative cost breakdown

Table 4-8 to Table 4-12 present an indicative cost estimate for each proposed options.

4.3.3.1 Option 1 - Variant A - Rock revetment repair with buried toe

Table 4-8 Indicative cost estimate for Option 1 – Variant A

Material Unit Cost

Excavation/backfill m3 $250,000

Crest and primary armour t $1,750,000

Secondary armour t $200,000

Fees and contingencies (Table 4-7)

N/A $2,000,000

Total $4,200,000

4.3.3.2 Option 1 - Variant B - Rock revetment repair with toe on existing surface

Table 4-9 Indicative cost estimate for Option 1 – Variant B

Material Unit Cost




N/A $1,300,000

Total $2,550,000

4.3.3.3 Option 1 – Variant C – Total rock revetment reconstruction

Table 4-10 Indicative cost estimate for Option 1 – Variant C

Material Unit Cost




Geotextile m2 $270,000


N/A $3,100,000

Total $6,620,000


4.3.3.4 Option 2 - Sand filled geotextile bags

Table 4-11 Indicative cost estimate for Option 2

Material Unit Cost


Geocontainers unit $2,500,000

Reinforced concrete m3 $2,000,000

Geotextile m2 $350,000


N/A $4,700,000

Total $10,300,000

4.3.3.5 Option 3 - Reinforced concrete stepped seawall

Table 4-12 Indicative cost estimate for Option 3

Material Unit Cost


Reinforced concrete m3 $13,000,000

Moisture barrier m2 $150,000

Armour rock t $450,000


N/A $11,750,000

Total $26,100,000

Important note regarding cost estimates

The above opinions of cost have been prepared by Aurecon at the request of Council, solely for use in

connection with the Tully Heads Seawall Condition Assessment project. Aurecon does not accept any

legal liability or responsibility in respect of the use of this opinion of cost for any purpose other than the

purpose defined above. Aurecon has exercised due skill, care and attention in preparing the opinion of

cost. Since Aurecon has no control over the cost of labour, materials, equipment or services furnished

by others, or over contractors’ methods of determining prices, or over competitive bidding or market

conditions, any opinion of costs is made on the basis of Aurecon's experience and qualifications and

represents its best judgement as an experienced and qualified professional engineer, familiar with the

construction industry; but Aurecon cannot and does not guarantee that proposals, bids or actual

construction cost will not vary from Aurecon’s opinion of cost


A Multi Criteria Analysis has been undertaken to compare a range of options plausible to mitigate the

erosion problem at Tully Heads.

Multi Criteria Analysis is a tool that can be used for complex problems where multiple criteria need to

be assessed in the process of making decisions about proposals for future action. Multi Criteria

Assessments (MCAs) attempt to incorporate all criteria simultaneously within the analysis, to arrive at

a single conclusion or ranking. As such, those assessments can consider a range of complex issues,

impacts and opportunities and can therefore be applied to more complex situations than a Cost

Benefit Analysis. For these reasons, an MCA process is used to inform the selection of a preferred

seawall option at Tully Heads.

5.1 Analysis criteria

The seawall options are assessed on the following themes: impact, effectiveness, social value,

government process and economics. The following sections outline factors taken into consideration for

each theme.

5.1.1 Impact

The impact or influence of a proposed option is a key consideration and generally relates to the

degree to which an option may change conditions from the status quo (perceived or otherwise

defined). Impacts can occur to the environment and to the community.

Marine biodiversity – the degree to which the option may impact marine biodiversity at Tully Heads, considering the benthic species associated with the beach, intertidal flats and the sub-tidal areas

Beach/dune biodiversity – the degree to which the option may impact beach and dune biodiversity (those areas typically above high tide mark), considering suitability to promote dune vegetation (re-vegetation) and the opportunity for re-colonisation by dune animal species

Environmental impacts beyond Carron Esplanade – the impact of the option on areas farther afield, including the impact on materials source areas, and up/down coast impacts due to changes in sand supply or generation of plumes etc.

Construction impact – in relative terms, the area directly affected by the proposed option, both in terms of option footprint as well as construction impacts for the materials sourcing areas. This criteria may also capture issues relating to the degree to which construction works may interfere with beach use

Construction timing – the time and flexibility taken to undertake construction (i.e. the degree to which external influences may restrict the timing of works)

5 Multi-criteria analysis


Non-beach users – the degree to which the option may impact on non-beach users within the community. For example, nourishment options that use quarried sand may impact non-beach users by way of increased truck traffic on local roads

5.1.2 Effectiveness

The effectiveness of the option to address the erosion problem is assessed via a range of criteria.

Consideration is given to both the upside (addressing the problem) and downside risks (failure

consequence) of each option as well as to specific uncertainties.

Longevity of design – consideration of design life under typical conditions

Incident wave problem – degree to which a solution directly attenuates incident waves, creating a reduced wave energy condition at the beach

Sand budget imbalance – degree to which a solution ameliorates the recognized imbalance between longshore supply and storm sediment transport

Shoreline recession – degree to which a solution reduces or eliminates beach recession

Failure consequence – the downside risk of failure of the proposed option, perhaps due to exposure to conditions beyond design criteria, where consequences could include potential loss of life or damage to public/private property and/or infrastructure

Technology challenges – measure of the uncertainty associated with proven versus new technology, and considers options proven/suitable for conditions at Tully Heads through to new technology unproven along the Cassowary Coast

Integration/compatibility with existing – measure of the difficulty to integrate the proposed option with the existing infrastructure

Adaptation to short term cyclic variations – degree to which the option can accommodate short term (seasonal, storm) cycles in sand supply, wave climate, water levels

Adaptation to long term changes – degree to which the option can accommodate long term (annual, climate change, ENSO) cycles in sand supply, wave climate, water levels

5.1.3 Social value/community expectations

The local and extended community of beach users have expectations about Googarra Beach. An

important measure of the appropriateness of the proposed solution option is the degree to which the

values held by the community can be preserved.

Visual amenity – degree to which the option meets with the community’s expectation of what Googarra Beach should look like, and/or the degree to which an option may detract from such expectations about the beach. It is understood that Tully Heads residents wish to protect the visual amenity and may be resistant to a higher wall.

Beach safety – issues such as safe access to the beach, safe beach user area, safe swimming, or safe use of recreational water craft

Sense of place – degree to which the option may alter the sense of place, or community connectedness to Googarra Beach

Suitability of materials – degree to which the community may accept proposed materials, recognizing the materials’ adaptability for use (or not) for stairs, walkways, informal seating and an assessment of other material specific issues including user-friendliness, colonization of pests, litter, maintenance and odour


5.1.4 Government processes

This theme considers the governmental process challenges associated with each option.

Roles and responsibilities – degree to which various local, state and federal government roles and responsibilities are clearly defined, and one end of the scale requiring significant effort to resolve (perhaps outside the existing policy scope) to being clearly set out within existing arrangements

Compliance with Coastal Protection and Management Act (CPMA) and Marine Park Act (MPA) – as a guiding principal, the CPMA and MPA is a crucial reference for proposed actions at Googarra Beach. This measure captures the degree to which the option is consistent with the CPMA and MPA policies and objectives

Approvals process – considers the requirements of approving the proposed option, whether secured via existing well understood pathways or requiring significant additional levels of approval not typical of “business as usual”

5.1.5 Economics

Cost is a major factor in any infrastructure project. Once completed, the seawall will become part of

the Cassowary Coast Regional Council portfolio of coastal assets and accordingly, capital cost is not

the only consideration.

Capital Cost – in relative dollar terms the up-front cost of the option, including material costs, site construction activities, and any environmental (or other) monitoring linked to the option

Maintenance Cost – the cost of periodic routine maintenance

Lifecycle cost – the total cost of the asset each year, over its design life

5.2 Option analysis

Table 5-1 summarises the findings of a MCA, prepared as a desktop level. It is important to consider

that this is not a final assessment and is subject to feedback from relevant stakeholders.

Colour coded cells have been included for each criterion and for each option. A green cell indicates a

low impact, an orange cell shows a medium impact and a red cell means the option triggers a high

impact.

The geotextile seawall would require more intervention year on year than most other seawall types. A

reinforced concrete stepped seawall is typically expensive to build and difficult to repair.

The rock revetment repair with buried toe is best suited for Seawall 1 at Tully Heads, provided that

sufficient armour stone can be procured economically. It is recommended to investigate local quarries

to confirm what armour stones can be provided locally and economically.


Table 5-1 Multi-criteria analysis


Various options were assessed to upgrade/replace Seawall 1 at Tully Heads. It is proposed to

upgrade Seawall 1 by adding a primary rock armour layer and burying the revetment toe under the

existing beach surface. Repairs of the crest of Seawall 2 are also proposed. This however is subject to

relevant stakeholder feedback.

Both Seawall 1 and Seawall 2 are mitigating the shoreline erosion along Tully Heads foreshore

however they are not flood control structures. Overtopping may occur behind the seawall crest. In

addition, the seawalls are not pedestrian accesses to the beach. A BCA compliant pedestrian access

stair should be considered as part of detailed design, or an alternate system implemented to deter

unauthorised access across the wall.

Detailed geotechnical investigations and site survey (including buried material) are required to confirm

the concept option assessment details.

Detailed design, development approval consultations, project management, selection of an

appropriate contract for construction, contractor engagement and on-going construction management

are recommended to detail the cost estimates further and to provide control on future cost changes.

Physical model testing is recommended during the detailed design phase to optimise the seawall

structure and reduce capital costs.

6 Conclusion


1. Australian/New Zealand wind load standard AS/NZS 1170.2:2011

2. BMT WBM (2009) Tully Heads to Hull Heads Shoreline Erosion Management Plan – Final

Report

3. CIRIA (2007) The Rock Manual – The use of rock in hydraulic engineering

4. Coastal Engineering Guidelines for working with the Australian coast in an ecologically

sustainable way, Engineers Australia, May 2012

5. Department of Environment and Heritage Protection Operational Policies for Coastal

Development

http://www.ehp.qld.gov.au/coastal/development/operational_policies.html

6. Building and engineering standards for tidal works, DEHP, 2013

7. GHD (1992) Tully Heads Seawall, Report on Stability of Seawall

8. GHD (2011) Post Yasi Cyclone Inspections, Tully Heads Rock Seawall (portion of the report)

9. JT Smith and Associates Pty Ltd (2011) Restoration of seawalls and other works, South

Mission Beach and Tully Heads

10. Hardy T, Mason L, Astorquia A, Queensland Climate Change and Community Vulnerability to

Tropical Cyclones: Ocean Hazards Assessment Stage 3 – The Frequency of Surge Plus Tide

During Tropical Cyclones for Selected Open Coast Locations Along the Queensland East

Coast. Marine Modelling Unit, School of Engineering, James Cook University, August 2004

11. Overtopping Neural Network online calculator

http://www.deltares.nl/en/software/630304/overtopping-neural-network

12. Maritime Safety Queensland (2014) Tidal planes [online] www.msq.qld.gov.au/Tides/Tidal-

datam-information.aspx

13. Tully Heads Original Design Drawings

14. U.S. Army Corps of Engineers (2006) Coastal Engineering Manual – Part II, Chapter 2

15. U.S. Army Corps of Engineers (2006) Coastal Engineering Manual – Part VI, Chapter 5

16. Wave overtopping of sea defences and related structures: assessment manual, 2007,

EurOtop

7 References

http://www.ehp.qld.gov.au/coastal/development/operational_policies.html

http://www.deltares.nl/en/software/630304/overtopping-neural-network

Appendices

Appendix A Document register

Project 243333 File Appendix A - Document Register.docx 24 October 2014 Revision 1 Page 1

Title Description Prepared by Date

1992 Upgrade of Seawall 1

s.86 Harbours Act – Beach Protection Authority Assessment

Correspondence from the Beach Protection Authority to Cardwell Shire Council stating no objection letter to proposed upgrade of 370 m rock wall at Tully Heads.

Beach Protection Authority

20.11.1992

s.86 Harbours Act Correspondence from Queensland Transport to Cardwell Shire Council granting sanction – Tully Heads Rock Wall – Stages 1 and 2 (Ref 2-19-3396T)

Queensland Transport

10.12.1992

Drawing 16566-1 (in 4 prints)

Tully Heads Seawall, Seawall Plan and Details

GHD 1992

s.47 Approval of Rock Seawall at Tully Heads

Correspondence from the Beach Protection Authority to Cardwell Shire Council granting a s.47 approval.

Beach Protection Authority

11.01.1993

1996 Revetment Wall Extension (16 m) Seawall 2

Extension of Revetment Wall at Tully Heads

Correspondence from the Queensland Department of Environment – Sanction under s.86 of the Harbours Act – 16 m Revetment Wall Extension

Queensland Department of Environment

2.12.1996

Drawing BP97.01 Tully Heads Seawall Extension South End at Taylor Street, Site Plan and Details

Cardwell Shire Council

1996

2006 Construction of Seawall 2

Decision Notice Approval in Full with Conditions – Prescribed Tidal Works (Installation of a Rock Wall) Taylor Street, Tully Heads (Reserve) Lot 10 on CWL802853


15.12.2006

Concurrence Agency Response

Environmental Protection Agency to Cardwell Shire Council – Concurrence Agency Response – Granted in full with conditions

Environmental Protection Agency (ecoaccess)

30.10.2006

Plan 3811 Cross-Section Adjacent to Pocket Beach (Lot 9 T9483)

International Coastal Management (ICM)

2006

Drawing TH-A3-01 Location and Site Plan ICM 2006

Drawing TH-A3-02 Plan ICM 2006

Drawing TH-A3-03 X-Section ICM 2006

- Cardwell Shire Council – Prescribed Tidal Works – Application File 146/06

IDAS Forms and Design Drawings


-

- Correspondence from International Coastal Management (ICM) to the Department of Natural Resources and Mines (DNRM) requesting resource consent

ICM March 2006

April 2006

Project 243333 File Appendix A - Document Register.docx 24 October 2014 Revision 1 Page 2

Title Description Prepared by Date

Correspondence from International Coastal Management (ICM) to the Environmental Protection Agency (EPA) submitting application for assessment – extension of existing rock wall at Tully Heads

ICM November 2004

Officer Report DA 146/06 Report Number W655

Officer’s Recommendation Report – Development Application for Prescribed Tidal Works

John Pettigrew (Deputy Director Engineering Services)

November 2006

Contract T01/06-07 Construction of a Seawall at Tully Heads

Correspondence –Cardwell Shire Council to Jenkins Earthmoving

22 June 2007

Construction of Rock wall, Taylor Street, Tully Heads, at and adjacent to Lot 10 CWL802853

Correspondence – Condition A1C3 – Results of Site Inspection undertaken by EPA officer on Thursday 17 January 2008

1 February 2008

Reference

Report on Stability of Seawall, Tully Heads Seawall

- GHD 1992

Post Yasi Cylcone Inspections, Tully Heads Rock Seawall

Section of report GHD 2011

Restoration of Seawalls and other Works, South Mission Beach and Tully Heads

- J T Smith and Associates Pty Ltd

March 2011

Tully Heads and Hull Heads Shoreline Erosion Management Plan

Final Report BMT WBM April 2009

Other Documents Received (Outside Scope)

Drawing BP97.02 Installation of a Trial Groyne at Tully Heads Cardwell Shire Council

1997

Appendix B Option Assessment Drawings

CLIENT

DATE

TITLE

REVISION DETAILSDATEREV APPROVED

CHECKED

APPROVED

PROJECT

DRAWN

DESIGNED

PROJECT No. TYPE REVWBS DISC NUMBER

DRAWING No.

SCALE SIZE

A1

.

CONCEPT DESIGN SEAWALLTULLY HEADS

DRAWING SCHEDULE AND NOTES

243333 0000 DRG LA 0001 A

NOT TO SCALEPRELIMINARY

NOT FOR CONSTRUCTION

K.HADZIVUKOVIC

J.FARNES

A 15.12.14 ISSUED FOR CLIENT REVIEW GC

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243333-0000-DRG-LA-0001 DRAWING SCHEDULE AND NOTES

243333-0000-DRG-LA-0002 SITE LAYOUT

243333-0000-DRG-LA-0003 SEAWALL OPTION 1 - TYPICAL SECTIONS

243333-0000-DRG-LA-0004 SEAWALL OPTIONS 2 & 3 - TYPICAL SECTIONS

243333-0000-DRG-LA-0005 SEAWALL OPTIONS - PUBLIC ACCESS STAIR

CONCEPT DESIGNTULLY HEADS SEAWALL

SCHEDULE OF DRAWINGS

HAT 1.941.040.33

-0.19

-1.68

LEVEL AHD (m)

-0.89

TIDAL LEVELS *

MHWSMHWNMSLMLWNMLWSLAT

* - TIDAL LEVELS ASSUMED TO BE SIMILAR TO CLUMP POINT

50 2.55

AVERAGE RECURRENCEINTERVAL (A.R.I. YEAR)

STORM TIDE LEVELS **

PRESENT SEA LEVEL(m AHD)

2.25

** - BASED ON CARDWELL INUNDATION STUDY

2064 SEA LEVEL(m AHD)

50 34.7

AVERAGE RECURRENCEINTERVAL (A.R.I. YEAR)

DESIGN PARAMETERS

WATER LEVEL(m AHD)

2.55

# - WIND SPEED IS PER AUS STD AS1170.2 (HOURLY SPEED AT 10m/s)

WIND SPEED(m/s) #

2.75

SIGNIFICANT WAVEHEIGHT Hs (m)

5 to 7

DESIGN WAVE PEAKPERIOD Tp (s)

GREENHOUSE EFFECT

1. SEA LEVEL RISE = 0.3m (2064)

SCOUR ALLOWANCE

1. SEAWALL TOE IS BURIED TO LAT (-1.68m AHD)

GENERAL NOTES:

1. THE POSITION AND DIMENSIONS OF SEAWALL OPTIONSARE INDICATIVE ONLY.

2. DRAWINGS SHALL BE READ IN CONJUNCTION WITH TULLYHEADS SEAWALL OPTION ASSESSMENT REPORT

3. THE SEAWALL IS ONLY AN EROSION CONTROL STRUCTUREAND IS NOT DESIGNED FOR FLOOD CONTROL

4. EXISTING SOIL ELEVATIONS ARE APPROXIMATE ONLY

DRAWING No. DESCRIPTION

0.05

25T948624T9486 22RP846516 12T9486 11T9486 10T9486 9T9486

14T9486 15T9486 16T9486 17T9486 18T9486 19T9486 20T9486

1T9486

2T94861RP7381555T94866T94867T9486

8T9486

13T948514T9485 15T9485 16T9485 17T9485 18T9485

7T94858T94859T948510T948511T948512T9485

12T9487

11T9487 10T9487 9T9487 8T9487 7T9487

642T9484

39T9482

40T9482

1RP735394

43T9482 1RP738156

35T9482

36T948237T9482

38T9482

906T9482 905T9482 904T9482 903T9482 902T9482 901T9482 9T9483 1RP865399

4RP736730

3RP736730

2T9483 1T9483

10CWL802853

2RP865399

1AP5889

2AP5889

16T948222T948223T948224T948225T9482

26T9482

27T9482

28T9482

907T9482908T9482909T9482910T9482911T9482912T9482

13T9484

CLIENT

DATE

TITLE


CHECKED

APPROVED

PROJECT

DRAWN

DESIGNED


DRAWING No.

SCALE SIZE

A1

.


SITE LAYOUT

243333 0000 DRG LA 0002 A

1:1000PRELIMINARY


S.LEMON

J.FARNES


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TAYLOR ST

CARRON ESP

X

TULLY RIVER

GALM

AHRA

ST

LEGENDWARNING SIGN LOCATION (APPROXIMATE)READING: "ROCK WALL MAY BE UNSTABLE. TOAVOID INJURY DO NOT CLIMB OR CROSS WALLS"

TAYLOR ST

CARRON ESP

TOE OFEXISTINGSEAWALL

TOP OF EXISTINGSEAWALL

TOE OFEXISTINGSEAWALL

TOP OFEXISTINGSEAWALL

BEACH ACCESS(PRIVATELY BUILT)

SEAWALL 1 SEAWALL 2

HAT

MHWS

HAT

MHWS

NOTES1. AERIAL IMAGE CIRCA 2011

LOCATION OF EXISTINGSURFACE FOR CROSSSECTION PURPOSES

EPROPOSEDPUBLICACCESS STAIR

PROPOSEDSEAWALL EXTENT

PROPOSED CRESTREPAIR EXTENT.REFER TO SECTION 4OF THE OPTIONASSESSMENT REPORT

CLIENT

DATE

TITLE


CHECKED

APPROVED

PROJECT

DRAWN

DESIGNED


DRAWING No.

SCALE SIZE

A1

.


SEAWALL OPTION 1TYPICAL CROSS SECTIONS

243333 0000 DRG LA 0003 A

1:50PRELIMINARY


S.LEMON

J.FARNES


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1. REFER DRG. LA-0001 FOR NOTES.2. EXISTING SURFACE VARIES. REFER DRG.

LA-0002 FOR LOCATION OF EXISTINGSURFACE SHOWN ON OPTION SECTIONS.

3. ALL LEVELS IN METRES TO AHD.4. ALL DIMENSIONS IN MILLIMETRES UNO.

NOTES:

EXISTING ROCK ARMOUR TO BERELOCATED. LAYER THICKNESSSHALL BE GREATER THAN1000mm. ALL HOLES TO BE FILLED

ADDITIONAL ROCKSM 50 = 300kgTHICKNESS = 1000mm (MIN.)

OPTION 1 - VARIANT BREVETMENT REPAIR WITH SURFACE TOE

SECTION XB-1:50

OPTION 1 - VARIANT AREVETMENT REPAIR WITH BURIED TOE

SECTION XA-1:50

ARMOUR ROCKSM 50 = 3000kgTHICKNESS = 2100mm (MIN.)

RL 0.05 (MSL)

RL -1.68 (LAT)

RL -0.89 (MLWS)

RL 1.94 (HAT)

RL 1.04 (MHWS)

RL 0.00 (AHD)


ADDITIONAL ROCKSM 50 = 300kgTHICKNESS = 1000mm (MIN.)

EXISTING ROCK ARMOUR TO BERELOCATED. LAYER THICKNESSSHALL BE GREATER THAN1000mm. ALL HOLES TO BE FILLED

1.5

1

1

1RL 3.50(APPROX.)

RL 3.50(APPROX.)

1.5

1

RL 2.55DESIGN WATER LEVEL

RL 2.55DESIGNWATER LEVEL

RL 4.00 (NOM.)

CREST ROCKSM 50 = 6000kg APPROX.PATTERN PLACED

RL 4.00 (NOM.)

EXISTING ROCKPROTECTION/SEAWALL TO BECONFIRMED BY SURVEY

EXISTING SURFACE(REF. NOTE 2)

EXISTING SURFACE (REF. NOTE 2)

OPTION 1 - VARIANT CTOTAL ROCK REVETMENT RECONSTRUCTION

SECTION XC-1:50


RL 3.50(APPROX.)

RL 4.00 (NOM.)1.5

1

1

1

SECONDARY ARMOURM 50 = 300kgTHICKNESS = 1000mm (MIN.)


3200 (MIN.)1.5

1GEOTEXTILEELCOMAX 600R(OR EQUIVALENT)

NEW PROFILE


RL 0.05 (MSL)

RL -1.68 (LAT)

RL -0.89 (MLWS)

RL 1.94 (HAT)

RL 1.04 (MHWS)

RL 0.00 (AHD)



3200 (MIN.)

3200 (MIN.)

2400

600 18

00

CLIENT

DATE

TITLE


CHECKED

APPROVED

PROJECT

DRAWN

DESIGNED


DRAWING No.

SCALE SIZE

A1

.


SEAWALL OPTIONS 2 & 3TYPICAL CROSS SECTIONS

243333 0000 DRG LA 0004 A

1:50PRELIMINARY


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OPTION 2GEOCONTAINER SEAWALL

RL 0.05 (MSL)

RL -1.68 (LAT)

RL -0.89 (MLWS)

RL 1.94 (HAT)

RL 1.04 (MHWS)

RL 0.00 (AHD)


REINFORCEDCONCRETE CREST


NEW PROFILE

GEOTEXTILE ELCOMAX600R (OR EQUIVALENT)

2.5m³ ELCOROCKGEOCONTAINERS

1.5

SECTION A-1:50

1

OPTION 3REINFORCED CONCRETE STEPPED SEAWALL

SECTION C-1:50

ENGINEEREDFILL

TYP. 2.5m³ GEOCONTAINER DIMENSIONS

RL 3.50(APPROX.)

RL 4.00 (NOM.)

1.5

1


710TYP.

380

TYP.

REINFORCED CONCRETESEAWALL

ROCK SCOURPROTECTION

ENGINEEREDFILL

ROCK SIZE TO BECONFIRMED PENDINGGEOTECHNICALINVESTIGATION.

PRECAST REINFORCEDCONCRETE TOE


1

1

RL 3.50(APPROX.)

1

1


TURFSURFACING

NOTES:

MOISTUREBARRIER

CLIENT

DATE

TITLE


CHECKED

APPROVED

PROJECT

DRAWN

DESIGNED


DRAWING No.

SCALE SIZE

A1

.


SEAWALL OPTIONSPUBLIC ACCESS STAIR

243333 0000 DRG LA 0005 A

1:50PRELIMINARY


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PROPOSED PUBLIC ACCESS STAIRSECTION ELA-00021:50

RL 0.05 (MSL)

RL -1.68 (LAT)

RL -0.89 (MLWS)

RL 1.94 (HAT)

RL 1.04 (MHWS)

RL 0.00 (AHD)


RL 3.50(APPROX.)

REFER SECTION D ONDRG. LA-0003 FOR TYPICALROCK SEAWALL DETAILS.

ADDITIONAL ROCK ANDGEOTEXTILE BELOWCONCRETE STAIR BASE

RL 4.65 NOM.

DRIVEN PILES(8 TOTAL)

TIMBER ACCESS STAIRSAND HANDRAILING (TOB.C.A. STANDARDS)




NOTES:

EXISTING SURFACE(REF. NOTE 2)

Appendix C Approved Plans of Development – existing Seawall 1 and Seawall 2 C1 – Sanctioned Plans under Section 86 of the Harbours Act 1955 (repealed) prepared by GHD, dated 1992 – Seawall 1

C2 – Sanctioned Plans under Section 86 of the Harbours Act 1955 (repealed) prepared by the former Cardwell Shire Council, dated 1996 – Extension of Seawall 1

C3 – Sanctioned Plans under Development Permit for Operational Works that are Prescribed Tidal Works prepared by International Coastal Management, dated December 2006 (Permit IPCC00419906C11) – Seawall 2

15 December 2006

Decision Notice APPROVAL

Integrated Planning Act 1997 S 3.5.15

D/A146/06

John Pettigrew (Deputy Director, Engineering Services)

07 40439101


PO Box 401

TULLY QLD 4854

Dear Sir

RE: Application for Prescribed Tidal Works (Installation of a Rock Wall)

Taylor Street, Tully Heads (Reserve)

Lot 10 on CWL802853; Parish of Rockingham

I wish to advise that, on 14 December 2006, the above development application was -

� approved in full;

OR

� approved in part;

OR

� approved in full with conditions. The conditions relevant to this approval are attached.

These conditions are clearly identified to indicate whether the assessment manager or a concurrence agency imposed them;

OR

� approved in part with conditions.

416348:JWP/tn

Planning Services 4043 9101

4068 1772

1. Details of the approval -

The following type of approval has been issued - Development Permit

Preliminary Approval

• Carrying out building work (assessable against the Standard Building Regulation 1993)

• Reconfiguring a lot

• Material change of use made assessable by the planning scheme;

• Associated work made assessable by the planning scheme -

• building works

• operational works

• Material change of use for an environmentally relevant activity

• Material change of use for a licensed brothel

• Material change of use on strategic port land, inconsistent with an approved land use plan

• Making a material change of use for a major hazard facility or possible major hazard facility

• Planning scheme works -

• building works

• operational works

• Operational works for the clearing of native vegetation on land protected under the Vegetation Management Act

• Operational work for a referable dam or that will increase the storage capacity of a referable dam by more than 10%

• Operational work for tidal work or work within a coastal management district

�

• Development for removing quarry material from a watercourse or lake (if an allocation notice is required under the Water Act 2000)

• Operational work that allow taking, or interfering with, water (other than using a water truck to pump water)

• Development in a heritage registered place -

• Building work assessable against the Standard Building Regulation 1993

• Building work assessable against the planning scheme

• Material change of use

• Reconfiguring a lot

• Operational work

2. The relevant period -

�the standard relevancy periods stated in section 3.5.21 of IPA apply to each aspect of

development in this approval;

OR

� An alternative relevant period.

3. The approved plans -

The approved plans and / or documents for this development approval are listed in the following table -

Plan / Document

Number

Plan / Document Name Date

TH-A3-01 Location & Site Plan – Erosion Protection Works prepared by

International Coastal Management

1/3/2006

TH-A3-02 Plan – Erosion Protection Works prepared by International Coastal

Management

1/3/2006

TH-A3-03 X-Section – Erosion Protection Works prepared by International Coastal

Management

1/3/2006

4. Other necessary development permits – Nil.

5. Codes for self-assessable development – Not applicable.

6. Superseded planning scheme – Not applicable.

7. Preliminary approval overriding the planning scheme – Not applicable.

8. IDAS referral agencies -

The IDAS referral agencies applicable to this application are –

A. Referrals - triggered by building work assessable against the Standard Building Regulation 1993 – Nil.

B. Referrals – triggered by other assessable development under schedule 8 of the IPA

OPERATIONAL WORK

Operational work… Name of agency Status Address

1. For filling or excavation (not associated with reconfiguration) impacting on a State-

controlled road

Dept. of Main Roads � Concurrence

� Advice

2. For clearing native

vegetation

Dept. of Natural

Resources & Mines

Concurrence


3. That allows taking or interfering with water

under the Water Act 2000

Dept. of Natural Resources & Mines

Concurrence

4. Controlling the flow of water in drainage and

embankment areas

Dept. of Natural Resources & Mines

Concurrence

5. For a referable dam or that

will increase the storage of a referable dam by more than

10%

Dept. of Natural

Resources, Mines & Energy

Concurrence

� 6. That is tidal work other than

Prescribed Tidal Work in a Canal.

Environmental Protection Agency

�Concurrence Cairns District Office

(EPA)

PO Box 2066

CAIRNS QLD 4870

7. Within a coastal management district, that

is the disposing of dredge

spoil or other solid waste material in tidal water, other

than under an allocation notice under the Coastal Protection and Management Act 1995

Environmental Protection Agency &

Qld Transport

Concurrence

8. Within a coastal

management district, for draining or allowing drainage

or flow of water or other matter across State coastal

lands above high water mark

Environmental

Protection Agency

Concurrence

9. Within a coastal management district, in a

watercourse and not assessable under schedule 8,

part 3, items 3B and 3C of the IPA


Concurrence

10. Within a coastal management district, that is reclaiming

land under tidal water


and Qld Transport

Concurrence


is constructing an artificial waterway associated with

reconfiguration


and Qld Transport

Concurrence



is constructing an artificial waterway not associated with

reconfiguration, on land other

than State coastal land, above high water mark if the

surface area of water in the waterway is at lease 5 000m2


Concurrence


is constructing a bank or

bund wall to establish a ponded pasture on land,

other than State coastal land, above high water mark


Concurrence


is removing or interfering

with coastal dunes on land other than State coastal land,

that is in an erosion prone area and above high water

mark.


Concurrence

15. That is tidal work that involves a marina with

more than 6 vessel berths

Queensland Fire and Rescue Service

Advice

ALL ASPECTS OF DEVELOPMENT

Development… Name of agency Status Address

16. Below high water mark and within the limits of a port

The Port Authority for the land

� Concurrence

� Advice

17. For the removal of quarry material if an allocation

notice is required under the

Water Act 2000


Concurrence

18. In a heritage registered

place

Queensland Heritage

Council

Concurrence

19. For a mobile and

temporary environmentally relevant

activities (ERA)

Environmental

Protection Agency

Concurrence

C. Referrals – triggered by the assessment of the application against a local government planning instrument – Nil.

9. Submissions -

The application was not subject to public notification and therefore no submissions were received.

10. Appeal rights -

Attached is an extract from the Integrated Planning Act 1997 which details your appeal rights regarding this decision.

11. When the development approval takes effect -

This development approval takes effect -

• from the time the decision notice is given, if there is no submitter and the applicant does not appeal the decision to the court

OR

• when the submitter’s appeal period ends, if there is a submitter and the applicant does not appeal the decision to the court

OR

• subject to the decision of the court, when the appeal is finally decided, if an appeal is made to the court.

This approval will lapse unless substantially started within the above stated currency periods (refer to sections 3.5.19 and 3.5.20 of IPA for further details).

If you wish to discuss this matter further, please contact Council’s Deputy Director, Engineering Services, Mr John Pettigrew, on the above telephone number.

Yours faithfully MARK KELLEHER CHIEF EXECUTIVE OFFICER cc: Referral agency Environmental Protection Agency Cairns District Office PO Box 2066 CAIRNS QLD 4870

ASSESSMENT MANAGER’S CONDITIONS:

1. Works are to be performed generally in accordance with plans dated 1 March 2006 and documentation submitted to Council on 15 May 2006 by International Coastal Management all relating to Development Application No. 146/06.

2. Prior to the commencement of any construction, the Design Engineers must submit certification that the design complies with all requirements of the “IDAS Code for Development Applications for Prescribed Tidal Works”.

Concurrence Agency Conditions:

Prescribed Tidal Work Agency Interest: Coastal - structures

EPA Permit Number: IPCC00419906C11

Assessment Manager reference: 146/06 Date application received by EPA: 02-JUN-2006 Permit Type: Concurrence Response for Operational

Work

Decision: Granted in full with conditions Relevant Laws and Policies: Coastal Protection and Management Act

1995 and any subordinate legislation.

Jurisdiction: Item 9 in Table 2 of Schedule 2 of the

Integrated Planning Regulation 1998.

Development Description

Property Lot/Plan Aspect of Development

Carron Esplanade, Lot 10 Plan CWL802853 Prescribed Tidal Work -

Tully Heads and adjacent to Lot 1 and Rock Revetment 2 RP865399.

CONDITIONS OF APPROVAL: (A1C1) All works are to be constructed in accordance with the attached

approved drawings listed in the approved plans section in the notice

attached to this concurrence agency response. (A1C2) Record, compile and keep all monitoring results required by this

document and present this information to the Environmental Protection

Agency upon request. (A1C3) Sand nourishment to cover the rock revetment must be

commenced immediately following the completion of the rock revetment and must be completed within thirty (30) days. The sand nourishment to

be undertaken to cover the rock revetment must be to a minimum level of RL2.0 metres (Australian Height Datum), and maintained to this level, with a profile slope 1 on 4.

(A1C4) If the erosion scarp at the pocket beach adjacent to the Public

Park Reserve (Lot 9 on T9483) advances onto this Reserve, sand nourishment must be immediately undertaken and maintained to the

profile as shown on Cardwell Shire Council drawing 3811, Sh. 2 of 2, and be completed within thirty (30) days. The end walls (wings) of the rock

revetment must be covered with sand at all times to ensure erosion does not progress in behind the rock revetment.

(A1C5) Monitoring (beach profile surveying) must be undertaken at a

distance of 25 and 50 metres north of the northern end wall of the revetment. Such monitoring must be undertaken annually, and this

monitoring information be made available to the EPA upon request.

(A1C6) All temporary works associated with the construction of the revetment wall are to be removed from the site at the completion of the

works and all wastes shall be collected from the site by the permittee and

disposed of at a licensed waste facility. (A1C7) All reasonable and practicable measures must be taken to

prevent contamination of the beach and coastal waters as a result of silt run-off, oil and grease spills from machinery and concrete truck washout.

Concrete agitator wash out must only be conducted in a specified area to facilitate the removal of waste concrete from the area to landfill.

Wastewater from cleaning equipment must not be discharged directly or in-directly to any watercourses or stormwater systems.

(A1C8) No sand is to be removed from the coastal dune system within the erosion prone area or coastal management district. Material identified

as untreated Potential or Actual Acid Sulfate Soil is excluded from this

requirement provided the material is sufficiently treated to prevent the release of contaminants to water.

(A1C9) All organically enriched sand removed from the top layer

(topsoil) within the proposed development area must be stockpiled separately prior to excavation and used landward of the crest of the revetment wall. On completion of the works any excess organically

enriched sand material may be removed from the site. The area landward from the crest of the revetment wall must be maintained as a pedestrian

and maintenance access.

(A1C10) Acid sulfate soils must be managed such that contaminants are not directly or indirectly released from the works to any waters.

(A1C11) The sand being placed on the beach shall be clean and free of silt, clay, organic material or any other deleterious substance and must be of a grain size compatible with the existing beach sand.

(A1C12) The Cardwell Shire Council shall be responsible for the ongoing

maintenance of the revetment wall and the removal of any debris from the beach as a result of any damage to the wall.

DEFINITIONS:

Words and phrases used throughout this permit are defined below. Where a definition for a term used in this permit is sought and the term is not defied within this permit the definitions provided in the relevant legislation shall be used.

“administering authority” means the Environmental Protection Agency or its successor.

“approval” means ‘notice of development application decision’ or ‘notice of

concurrence agency response’ under the Integrated Planning Act 1997. “approved plans” means the plans and documents listed in the approved plans

section in the notice attached to this development approval. “artifical waterway” means an artificial channel, lake or other body of water.

Artificial waterway includes –

• An artificial channel that is formed because the land has been reclaimed from

tidal water and is intended to allow boating access to allotments on subdivided land;

• Other artificial channels subject to the ebb and flow of the tide; and

• Any additions or alterations to an artificial waterway. “canal” means an artificial waterway surrendered to the State. A canal is an artificial

waterway connected, or intended to be connected, to tidal water; and from which

boating access to the tidal water is not hindered by a lock, weir or similar structure. “coastal dune” means a ridge or hillock of sand or other material on the coast and

built up by the wind.

“dredge spoil” means material taken from the bed or banks of waters by using dredging equipment or other equipment designed for use in extraction of earthen material.

“Environmental Protection Agency” means the department or agency (whatever called) administering the Coastal Protection and Management Act 1995 or the Environmental Protection Act 1994. “erosion prone area” means an area declared to be an erosion prone area under section 70(1) of the Coastal Protection and Management Act 1995.

“high water mark” means the ordinary high water mark at spring tides.

“ponded pasture” means the ordinary high water mark at spring tides.

“quarry material” means material on State coastal land, other than a mineral within the meaning of any Act relating to mining. Material includes for example

stone, gravel, rock, clay, mud, silt and soil, unless it is removed from a culvert, stormwater drain or other drainage infrastructure as waste material.

“site” means land or tidal waters on or in which it is proposed to carry out the

development approved under this development approval. “tidal water” means the sea and any part of a harbour or watercourse ordinarily

within the ebb and flow of the tide at spring tides.

“watercourse” means a river, creek or stream in which water flows permanently or

intermittently –

• In a natural channel, whether artificially improved or not; or

• In an artificial channel that has changed the course of the watercourse.

“waters” includes river, stream, lake, lagoon, pond, swamp, wetland, unconfined surface water, unconfined water natural or artificial watercourse, bed and bank of any waters, dams, non-tidal or tidal waters (including the sea), stormwater

channel, stormwater drain, roadside gutter, stormwater run-off, and groundwater and any part thereof.

“works” or “operation” means the development approved under this development

approval.

“you” means the holder of this development approval or owner/occupier of the land which is the subject of this development approval.

APPROVED PLANS:

Plan/Document No.

Plan/Document Name Date

TH-A3-01 Location and Site Plan 1/03/06

TH-A3-02 Rev.B Plan 1/03/06

TH-A3-03 Rev.A X-Section 1/03/06

3811 Cross Section Adjacent to pocket beach (Lot 9 T9483)

Showing Profile to be

maintained by council.

Aug 06

End of Conditions.

Aurecon Australasia Pty Ltd

ABN 54 005 139 873

Level 1, 242 Mulgrave Road Cairns QLD 4870

PO Box 7625 Cairns QLD 4870 Australia

T +61 7 4019 6400

F +61 7 4051 2540

E [email protected]

W aurecongroup.com

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