EIS 531 ABOI 8625 Port Hacking tombolo : environmental ...

EIS 531

ABOI 8625

Port Hacking tombolo : environmental impact statement --

addendum, June 1988

NSW DEPT PDIMARY INDUSTRIES

II!III

A3018625

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WBLIC WRKS


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PORT HACKING TOMBOLO ENVIRONMENTAL IMPACT STATEMENT

Addendum, June 1988

prepared for PUBLIC WORKS DEPARTMENT NSW

by PLANNING WORKSHOP

in association with BRAYSHAW MACDONALD PTY LTD CHALLIS & ASSOCIATES PTY LTD COLSTON BUDD WARDROP & HUNT PTY LTD CONSULTING ENVIRONMENTAL ENGINEERS CONYBEARE MORRISON & PARTNERS MOUNT KING ECOLOGICAL SURVEYS PATTERSON BR1TTON & PARTNERS SCIENTFIC DIVERS MARINE STUDIES CENTRE, UNiVERSITY OF SYDNEY WILKINSON-MURRAY CONSULTING PTY LTD

PWD Report No. 87069 December 1987

87011 ISBN 07 30 546 187

Addendum: June 1988 Job No.8 8110

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I ENVIRONMENTAL IMPACT STATEMENT

PORT HACKING TOMBOLO

I ADDENDUM

I This addendum to the Environmental Impact Statement (EIS) has been prepared following the completion of physical modelling, and the finalisation of the design parameters of the tombolo concept as was foreshadowed in the original ElS. The

I addendum describes the amendments to the proposed works and, where relevant, assesses the impacts of the amended proposal upon the environment.

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I Planning Workshop June 1988

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CONTENTS

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INTRODUCTION

PART A: THE EXISTING ENVIRONMENT

DESCRIPTION OF THE SITE ............................... 1

DESCRIPTION OF THE MARINE ENVIRONMENT ............. 1

DESCRIPTION OF THE TERRESTRIAL ENVIRONMENT ........ 2

PLANNING CONTEXT ..................................... 2

PART B: DESCRIPTION OF TEE PROPOSAL

5. NEED FOR THE PROPOSAL ............................... 3

6. STATEMENTS OF THE OBJECTIVES OF THE PROPOSAL 3

7. GENERAL DESCRIPTION OF THE PROPOSAL ............... 3

8. PROPOSED DREDGING WORKS ............................ 4

9. PROPOSED CABBAGE TREE POINT TOMBOLO .............. 5

10. PROPOSED LILLI PILLI WORKS ............................ 8

11. CONSTRUCTION PROGRAMME AND ENERGY REQUIREMENTS 8

12. ALTERNATIVES TO THE CONSTRUCTION METHOD AND LANDSCAPE PLAN ....................................... 10

13. ENVIRONMENTAL PLANNING CONTROL ................... 10

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CONTENTS

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PART C: ENVIRONMENTAL IMPACT ASSESSMENT

14. PHYSICAL IMPACTS ON THE WATER BODY ................. 11

15. WATER QUALITY ........................................ 15

16. IMPACT ON THE MARINE ENVIRONMENT .................. 16

17. AIR QUALITY ............................................ 18

18. NOISE IMPACT ............................................ 18

19. VISUAL IMPACT ASSESSMENT ............................. 19

20. TRAFFIC AND PARKING .................................. 21

21. IMPLICATIONS FOR THE ROYAL NATIONAL PARK .......... 21

22. IMPACTS ON LAND AND WATERWAY USE .................. 22

23. SOCIO-ECONOMIC IMPACTS .............................. 24

24. SUMMARY OF ENVIRONMENTAL SAFEGUARDS ............. 24

25. CONCLUSIONS ........................................... 25

APPENDIX A: TABLES AND FIGURES

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INTRODUCTION

General

This addendum report has been prepared to incorporate into the Environmental Impact Statement the amendments resulting from detailed physical modelling of the tombolo as described in the initial EIS. In the normal progression of any engineering project from concept to detailed design, continual refinement is made to elements of the project. While the refinement of individual elements may be significant, it does not compromise the original concept. In the case of the Port Hacking tombolo, the original concept of the tombolo, dissipating wave energies and training tidal flows, remains. Section 9.4 of the EIS noted that the physical modelling was being used to finalise the detailed elements of the design, by ensuring that the position and orientation of the rock training wall and the alignment of the beach on the eastern side of the tombolo were optimised.

DEVELOPMENT OF THE MODIFIED PROPOSAL

Model Testing

Since finalisation of the EIS in 1987, work has proceeded on the detailed design of the tombolo. This work has principally involved the use of an undistorted 1:100 scale fixed bed hydraulic model of the lower estuary, constructed at the NSW Public Works Department's Manly Hydraulics Laboratory.

The modelling involved extensive testing of the existing (pre-tombolo) configuration, the tombolo configuration detailed in the EIS, and finally, the modified tombolo configuration as described in this addendum. The model reproduces a full range of wave directions, periods and amplitudes. During the model testing, spring and neap tide flows were simulated for both ebb and flood directions, and the effect of waves and tides were modelled both independently and concurrently. The ability of the physical model to combine wave action with tidal currents allowed further refinements of the earlier numerical modelling on which the EIS was based.

Prior to describing the modifications made to the design of the tombolo as a result of the model testing, it will be necessary to recapitulate on the manner in which the original dimensions of the tombolo and dredged channels were determined:

* The channel was fixed at a width of approximately 200 metres and a depth of four metres below ISLW. This ensured that tidal velocities were sufficient to achieve self-scouring but not so great as to present a hazard to navigation.

* As a result, the length of the tombolo sand mass was fixed at some 500 metres.

* The position of the tombolo eastern beach was determined by considerations of stability under storm-generated wave attack.

* The height and width of the tombolo sand mass was determined principally by storm demand but also by consideration of beach amenity.

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* The width of the tombolo sand mass and the nearshore zones determined

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the length of the rock training wall.

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I Model Testing Results

The principal results obtained from the physical model relate to water level

I variations at 13 fixed locations and current velocity vectors throughout the lower estuary. Water level variations were analysed using standard stochastic techniques. Velocity vectors were measured using standard laboratory techniques

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involving small paper drogues and time-lapse photography. The model testing highlighted several significant features of the hydraulic processes and these were used as a basis for refining the tombolo design. These were:

* A zone of flow separation was found to extend for some 50-80 metres north of the training wall and over its full length. This zone displaced

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tidal flows on to the northern side of the main channel with potentially adverse consequences for the stability of the southern margin of the Cunnamatta Bay shoal.

I * The physical model also revealed that between the training wall and the

northern extent of the zone of separation, there existed an area of low velocity within which negligible flow occurred. This effectively reduced the width of the channel for flow purposes. Consequently, peak

I velocities within the main channel increased to above the design level.

* The physical model generally confirmed the design wave climate on the

I seaward side of the tombolo and revealed substantial wave attenuation along the tombolo training wall.

' In light of the above findings, the tombolo and associated works have been modified as follows:

* The length of the tombolo sand body has been reduced from 500 metres

1 to approximately 400 metres. As a result, the northern end of the sand mass is some 140 metres south-west of its initial location.

I * A short spur wall will extend approximately 50 metres south-west from Hungry Point. The wall will have a crest elevation of approximately 1.0 metres above ISLW (ie, mid-tide level).

I * The dredging configuration has been varied. The channel between Hungry Point and the tombolo will be on average 240 metres wide at a depth of 4.0 metres ISLW. No dredging will be undertaken in the area

I south of Burraneer Point channel.

* The rock training wall at the northern end of the tombolo has been

I reduced in length by approximately 15 metres (to a length of 225 metres) and the crest height over the western-most 45 metres has been reduced from 4.5 metres above ISLW to 3.5 metres above ISLW).

I This addendum report has been prepared to assess the environmental effects of amending the proposal in this manner. To assist the reader in amalgamating the revised information about the proposal with the original ElS, the numbering of sections within the EIS has been retained.

An appendix has also been included, which contains amended tables and figures.

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PART A: TEL EXISTING ENVIRONMENT

DESCRIPTION OF THE SITE

1.1 General

Unchanged from the EIS.

1.2 Site Description

Essentially unchanged from the EIS. The site for the proposed spur wall extends approximately 50 metres into Port Hacking from the base of Hungry Point in a generally south-westerly direction.

The site for dredging works in the lower estuary has been amended, and generally extends from the mouth of Burraneer Bay in the west, to the mouth of the estuary approximately opposite Salmon Haul Bay.

A revised site plan is shown in Figure 1.2a.

1.3 Site Tenure


1.4 Use of the Site


1.5 Services and Structures

Essentially unchanged from the EIS. A revised plan showing approximate locations of services and structures is shown in Figure 1.5a.

1.5.1 Services

Essentially unchanged from the EIS.

The exact location of the submarine cables at Hungry Point will be established to ensure that they are not affected by the construction of the spur wall.

1.5.2 Structures


The remains of a concrete wall exist towards the south-eastern end of the rock platform at the base of Hungry Point.

DESCRIPTION OF TEL MARINE ENVIRONMENT


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I DESCRIPTION OF TEE TERRESTRIAL ENVIRONMENT

Essentially unchanged from the EIS. Where necessary, some sections

I have been amended to include reference to the site at Hungry Point.

13.1 Topography

As described in the EIS.

I Hungry Point lies at the southern extremity of the Cronulla Peninsula and rises to some five metres above sea level. The base of Hungry Point consists of a rock shelf extending some five metres into Port Hacking,

Igenerally in a south-westerly direction.

3.11 Archaeology

1 3.11.3 Archaeological Environment at Hungry Point

The archaeological environment of Hungry Point has been investigated, ' following the amendment of the proposal to include part of Hungry Point

within the site for the proposed works. The investigation included reference to previous archaeological studies and a site visit.

Advice from the National Parks and Wildlife Service is that an Aboriginal midden (Site No. 52-3-186) exists at Hungry Point. The site was fully investigated (Haglund, 1977), and it was determined that the existing buildings (now occupied by the Fisheries Research Institute) extend over much of the area occupied by the midden. The 1977 investigation also included a search of the eastern rock face of Hungry Point for engravings reputed to be there, but none were discovered.

The site was again investigated on 21st June 1988, and no engravings or any other evidence of Aboriginal occupation on or near the rock platform to which the Hungry Point spur wall is to be attached were discovered. A midden deposit in the vicinity of the site had been determined in the 1977 survey as being recent and already disturbed, and not extending down onto the rock platform.

PLANNING CONTEXT


4.1 Existing Zoning and Local Planning

4.1.1 Sutherland Planning Scheme


The construction of the Hungry Point spur wall embraces the use of the site for reclamation and is therefore permissible within the Waterways 7(a) zone.

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PART B: THE PROPOSAL

NEED FOR THE PROPOSAL


5.6 Justification for the Proposal

Essentially as described in the EIS. However, in reference to the justifications listed in the EIS (Section 5.6), the decision not to dredge south of Burraneer Point channel will mean that the opportunity for creating berms in the outer part of Simpsons Bay to facilitate research into the establishment of seagrass beds will be foregone.

STATEMENTS OF THE OBJECTIVES OF THE PROPOSAL


GENERAL DESCRIPTION OF THE PROPOSAL

7.1 Proposed Dredging Works

The proposal remains generally as described in the EIS, except that the volume of material to be dredged from the lower estuary is reduced from 570,000 cubic metres to 422,000 cubic metres.

7.2 Method of Dredging and Means of Disposal


7.3 The Proposed Tombolo

The concept of the tombolo is unchanged. However, the sand body has been reduced in length from 500 metres to approximately 400 metres and the training wall at its northern end has been reduced in height from 4.5 metres to 3.5 metres over the western-most 45 metres. The training wall has been increased from 6.0 metres to 6.5 metres over the central 15 metres. The length of the wall has been reduced from 240 metres to 225 metres.

A spur wall will be constructed in a generally south-westerly direction from Hungry Point. The wall will have a length of approximately 50 metres and will be constructed using only primary armour similar to that used on the tombolo training wall. Material for construction of the wall will be delivered from the tombolo site by barge.

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The total rock quantity remains at 51,000 tonnes as the additional rock needed for the spur wall is available from reductions in the length and

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7.4 Proposed Lilli Pull Works

IUnchanged from the EIS.

I B. PROPOSED DREDGING WORKS

I 8.1 Dredging Proposals


I 8.1.1 General Requirements

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8.1.2 Dredging in the Lower Estuary

I The navigation channel at the mouth of Gunnamatta Bay has been widened to an average width of approximately 240 metres.

IDredging South of Burraneer Point.

The area of the middle ground shoal to the south of the navigation channel which was proposed to be dredged to a depth of 2.0 metres below

I ISLW has been deleted from the proposal.

8.1.3 Dredging at Lilli Phi

I Unchanged from the EIS.

I8.2 Dredging Plan

Dredging plans for the lower estuary have been modified (refer Figure 8.1a). The revised individual dredging quantities are depicted in Table 1

I of the Appendix. It should be noted that the total volume of dredging for the project has been reduced from 640,000 cubic metres to 493,000 cubic

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8.3 Method of Dredging

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8.3.1 Method of Dredging in the Lower Estuary

I Unchanged from the EIS. However, with the deletion of the dredging of the area south of Burraneer Point channel, the role of the small dredge would be confined to the trimming of dredged slopes and high spots after

Ithe large dredge had finished.

8.3.2 Method of Dredging at Lilli Phil


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I I 8.4 Means of Disposal of Dredged Material


8.4.1 Means of Disposal of Dredged Material - Lower Estuary

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8.4.2 Means of Disposal of Dredged Material for the Liii P1111 Spit


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9. PROPOSED CABBAGE TREE POINT TOMBOLO

1 9.1 Description of the Tombolo

I The length of the sand body has been reduced from 500 metres to 400 metres (refer Section 7.3).

9.1.1 Description of Tombolo Sand Body

I Tombolo East Beach

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Dune system

I Unchanged from the EIS, except that dune crest height will taper from 6.5 metres above ISLW at the northern end to 6.0 metres above ISLW at the southern end to reflect marginally greater exposure of the northern

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West beach

I Unchanged from the EIS, except that the beach berm north of the gabion wall will be of variable width up to 30 metres.

I The total estimated sand volume in the tombolo is reduced from 570,000 cubic metres to 420,000 cubic metres.

I 9.1.2 Description of Tombolo Training Wall, Rock Gabion Wall and Hungry Point Spur Wall

I Unchanged from the EIS, except that the clear navigation distance between the end of the tombolo and the Hungry Point spur wall is approximately 240 metres.

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Training Wall Plan Configuration


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I I Training Wall Sections

The crest level has been reduced to 3.5 metres above ISLW over the

I western-most 45 metres (refer Figure 9.1a). The central 15 metres of the training wall would be raised to a height of 6.5 metres above ISLW to match the dune height (refer Figure 9.3a).

I Rock Gabion Wall


Hungry Point Spur Wall

I A 50 metre-long wall is to be built in a generally south-westerly direction from Hunqry Point. The wall will have a crest level of 1.0 metres above ISLW (approximately half tide level) and will be built entirely of five tonne armour stone. The wall would have a crest width I of approximately four metres and side slopes of 1:1.5 (vertical: horizontal) (refer Figure 9.3a).

I Rock Quantities

5 tonne Primary Armour 22,000 tonnes *

I 0.5 tonne Underlayer 6,000 tonnes Quarry Run 21,000 tonnes Rock Gabion Wall 2,000 tonnes

I Total 51,000 tonnes

* includes 4,000 tonnes for Hungry Point spur wall

9.2 Method of Construction

1 9.2.1 Method of Construction of Tombolo Sand Body


9.2.2 Method of Construction of Tombolo Training Wall and Rock Gabion Wall

I Essentially unchanged from the EIS.

Method of Construction of Hungry Point Spur Wall

I For the construction of the Hungry Point spur wall, armour rock would be placed directly from a barge which would be loaded from the tombolo site. No land-based plant or land access would be used on the Hungry

I Point site.

I 9.2.3 Truck Access

Unchanged from the EIS, except for minor adjustment to truck numbers (refer Table 11.1a), which does not affect the total number of truck movements during the construction period.

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9.3.1 Tombolo Sand Body


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9.3.2 Tombolo Training Wall and Rock Gabion Wall

Unchanged from the EIS. Note that the comments apply equally to the

I Hungry Point spur wall.

9.4 Physical Model

I The EIS indicated the use of a physical model to finalise elements of the detailed design of the tombolo. (Refer to the Introduction for further information on the model and model testing.)

1 9.5 Dune Stabilisation and Landscaping


I 9.5.1 The Tombolo Concept

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9.5.2 The Preferred Landscape Option

I The selection of the preferred option remains essentially as described in the EIS. However, this option has been modified after more detailed testing of the tombolo proposal. Whilst the concept of the tombolo

I remains unchanged, the physical and visual appearance of the tombolo has been altered as outlined in Sections 7.3 and 9.1.

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9.5.3 Landscape Masterplan

The Landscape Masterplan has been amended to take into account the

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revised tombolo plan (refer Figure 9.5a).

Planting

I Essentially unchanged from the EIS, although the final paragraph in this section should read:

"This succession of dune vegetation will be simulated on the I tombolo. In areas where the crest of the dune exceeds 12 metres in width, vegetation will consist of primary species and low secondary species on the seaward face and

I crest of the dune, with taller secondary species occurring on the leeward slope."

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Planting Programme


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I I Soil Enrichment

' Unchanged from the EIS.

Fencing


Paths


I Signposts

Unchanged from the EIS,

' Maintenance Road


Positioning of Rocks


I Tjmeframe for the Tombolo


PROPOSED LILLI PILL! WORKS


CONSTRUCTION PROGRAMME AND ENERGY REQUIREMENTS

1 11.1 Preliminary Staging and Constnjction Programme

11.1.1 General

Unchanged, except that Stage 3 of the lower estuary works would include construction of the Hungry Point spur wall.

11.1.2 Lower Estuary Works

I Stage 1 - Dredging

A large dredge and a small dredge would still be used, but with the deletion of the dredging south of the Burraneer Point channel, the role of

I the small dredge would be confined to the trimming of dredged slopes and high spots after the large dredge had finished.

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It is estimated that the large dredge will complete its work in 18 weeks and that the small dredge will be employed for a further six weeks on final trimming.

Stage 2 - Construction of Tombolo Sand Body

The time for construction of the sand body would be increased from 35 weeks to 39 weeks, due to phasing of activities of the large and small dredges (refer Figure 11.1a).

Stage 3 - Construction of Tombolo Training Wall

As per the EIS, except that the placement of 4,000 tonnes of 5 tonne rock to form the Hungry Point spur wall would be undertaken concurrently. The spur wall construction is estimated to take approximately four weeks. A revised preliminary construction programme is in Figure 11.1a.

Stage 4 - Tombolo Landscaping


11.1.3 Liii Pihi Training Works

Stage 1 - Dredging

Unchanged from the EIS, except that the small dredge would be available to undertake works at Lilli Pilli some eight weeks earlier than planned (refer Figure 11.1a).

11.2 Traffic Generation During Construction

Unchanged from the EIS (refer Table 11.1a).

11.3 Temporary Arrangements and Safeguards

Unchanged from the EIS, except that provision will need to be made for a navigation light on the spur wall.

11.4 Construction Workforce


Energy Requirements


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ALTERNATIVES TO THE CONSTRUCTION METHOD AND LANDSCAPE PLAN


12.1 Alternatives to the Landscape Plan


12.2 Alternative Access Routes


12.3 Alternative Dredging Methods


12.3.3 Dredging Alternatives: Conclusions

While the quantities to be dredged have been reduced, the conclusions regarding the use of either two small dredges or a single large dredge remain valid.

12.3.4 Training Wall Alternatives: Conclusions

It would be possible to construct the Hungry Point spur wall using land-based plant and this would be marginally less expensive than the proposed water-based method. The use of land-based plant would have a number of impacts including some 260 truck movements through suburban streets and possible disruption to operations of Fisheries Research Institute.

As water-based plant will be on site for the construction of the Lilli Pilli groynes, it will also be employed for the Hungry Point spur wall.

ENVIRONMENTAL PLANNING CONTROLS


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PART C: ENVIRONMENTAL IMPACT ASSESSMENT

14. PHYSICAL IMPACTS ON THE WATER BODY

14.1 Stability of the Proposed Works

14.1.1 Astronomical Tide Level and Extreme Elevated Ocean Water Levels


14.1.2 Currents


Tidal currents off Horderns Beach will be similar to pre-tombolo conditions and will be dominated by wave induced currents, as will currents off the tombolo beach.

14.1.3 Wind Climate


14.1.4 Wave Environment

Cabbage Tree Point Tombolo


Alignment of the Sand Body

The alignment has been slightly adjusted to ensure compatibility with the weighted mean inshore wave direction. Detailed examination of all available Port Hacking wave data as part of the physical model study has allowed the alignment of the beach to be accurately determined.

Height and Width of Tombolo

The height of the dune at the northern end of the tombolo has been increased from 6.0 metres above ISLW to 6.5 metres above ISLW.

The physical model also confirmed that:

* the 30 metre berm is sufficient to accommodate seasonal variations in wave direction, with a wave window of eight degrees;

* the combined effect of differential wave heights along the tombolo beach and angle of break creates limited littoral currents both north and south along the beach. Such currents are now evident to a similar degree along Horderns Beach.

Beach Profile

Unchanged from the EIS. The physical model confirms the design approach taken in the EIS.

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Rock Training Wall

Unchanged from the EIS, except that the inshore section of the wall has been reduced in length by 15 metres and in height by 1.0 metre. The central 15 metres of the wall has been increased in height by 0.5 metres.

Spur Wall

Design wave heights will be identical to that used for the training wall.

14.1.5 Sediment Movement


14.1.6 Maintenance Requirements

Unchanged from the EIS. Note that the spur wall will not require maintenance as it is also designed as a flexible structure and is therefore able to accommodate movement without adverse impact on its performance.

14.2 Impact of the Proposed Works on Physical Processes

14.2.1 Tides


14.2.2 Tidal Currents

The physical model provides additional information on currents in the lower estuary. The main points are:

* Entrance Channel - velocities will be about half those off Burraneer Point. For a spring tide range (10 per cent exceedance), average peak surface velocities in the order of 0.7 metres per second will occur. For a neap tide range (90 per cent exceedance), average peak surface velocities of 0.3 metres per second will occur.

* The model also shows the presence of a separation zone along the training wall for both flood and ebb tides. Velocities in the separation zone are very small.

* Simpsons Bay - velocities will be about half pre-tombolo values but will be greater than the velocities stated in the EIS.

* Cunnamtta Bay Mouth - tidal velocities across the shoal and in the Ounnamatta Bay navigation channel will be unchanged except that there will be an increase from the pre-tombolo condition in velocities at the southern margin of the shoal along the edge of the entrance channel under peak spring tides.

* off Horderns Beach - tidal velocities are small and unchanged (refer Section 14.1.2).

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14.2.3 Wind Climate

I Unchanged from the EIS, except that wind shadow of tombolo is reduced cosistent with the reduction in the length of the sand body.

14.2.4 Wave Environment

The physical model provides information on wave heights and their

I interaction with currents inshore of the tombolo which were not previously available.

Water level variations were measured at 13 fixed locations throughout

I the physical model (Figure 14.3a) for a range of conditions. Mean wave heights for a one year return period 12 hour storm are shown in Table 14.3a.

I Horderns Beach and Tombolo Beach

Wave heights and approach directions on Horderns Beach will be unchanged from the pre-tombolo condition. The wave heights on the tombolo beach will be slightly greater than at the northern portion of Horderns Beach. This is in accord with previous wave refraction analysis. The beach will be dissipative during major storm events, but reflective for the majority of time, similar to Horderns and Jibbon Beaches.

Entrance Channel

Wave heights in the channel are reduced for the post-tombolo condition. The most significant reductions are opposite the end of the Gunnamatta Bay channel.

Simpsons Bay

Ocean-generated waves will still reach the Bonnie Vale area but at a much reduced rate. Locally generated wind waves will dominate.

Gunnamatta Bay Mouth

Wave heights on the Gunnamatta shoal and in the channel into the Bay will be generally reduced. A marked decrease will occur on the lee of the spur wall in the vicinity of Hungry Point.

Off Burraneer Point

Wave heights will be reduced significantly.

14.2.5 Sediment Movement

Tombolo General

Essentially unchanged from the EIS, except that 420,000 cubic metres of sand will be removed directly from the channels.

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Lower Estuary Upstream of the Tombolo

I Unchanged from the EIS. Physical modelling indicates a potential for the formation of a linear bar on the edge of the main channel. However, after the initial settling down period, sediment supply will be very

I limited, and any significant development of the bar is unlikely.

Mouth of Gunnamatta Bay

I Tidal currents and wave heights will generally be reduced on the shoal and channel into the Bay and consequently, sediment movement will be

I greatly reduced. The potential for limited erosion along the boundary of the shoal and the main entrance channel during major storms remains, but can be mitigated by the adoption of flatter side slopes (1:10) along

I the main entrance channel.

Entrance Channel

Physical model testing confirms that there is no significant velocity I gradient along the main channel across the mouth of Cunnamatta Bay. The channel configuration will therefore be stable after an initial

I settling down period. particularly during this

One area where some accretion might occur, period, is in the separation zone along the

training wall.

Horderns Beach

As tidal currents, wave heights and directions will not be altered by the tombolo construction, sediment movement on Horderns Beach will remain unchanged.

14.3 Implications for Navigation

14.3.1 Lower Estuary

As stated in the EIS, except that the entrance channel will be some 240 metres wide, on average.

Mooring conditions at Hungry Point in the lee of the spur wall will be greatly improved because of the lower wave energy in this area.

14.3.2 Liii Pilli Area


14.4 Implications for Water-based and Foreshore Recreation

14.4.1 Altered Tidal Currents


14.4.2 Altered Wind Climate

Unchanged from the EIS, except that extent of the wind shadow has been reduced (refer Section 14.2.3).

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I 14.4.3 Altered Wave Climate

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14.5 Assessment of Impact

I These vary very little from the assessment, except the statement in relation to the northern side of the new entrance navigation channel can be taken as appying to all dredged channels - that is:

I "No adverse impacts on existing physical processes are envisaged as a result of the works. Localised changes will

I occur along the dredged channels, due to stirring action by waves and increases in tidal velocity. However, any such changes will be limited and will not affect the stability of the channels or the adjacent shoals."

I 1 15. WATER QUALITY

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15.2 Water Quality in Simpsons Bay

I The revised findings of the water quality report concluded that water particles would escape from Simpsons Bay in a single ebb tide, and wind-generated waves and local shoreline currents would provide rapid vertical

I mixing. Simpsons Bay would have a reasonably rapid flushing time of approximately one day, and therefore, would continue to have satisfactory water quality.

1 15.3 Effects of the Liii P1111 Spit


1 15.4 Water Quality Changes in the Bays of Port Hacking

I It was concluded that water quality in the upper estuary will be maintained and could even be enhanced as a result of the amended proposal.


Essentially unchanged from the EIS. It was concluded that the revised

I tombolo is satisfactory from a water quality viewpoint, and that the alterations to the tombolo may improve circulation and flushing in Simpsons Bay.

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I 1 16. IMPACT ON TEE MARINE ENVIRONMENT

I environment. The amended proposal was assessed for its impacts upon the marine

The results are as follows.

16.2 Nutrient Cycling and Planktonic Communities

1 16.2.1 Simpsons Bay Gunnamatta Bay and


16.3 Sandy Unvegetated Shoals

I The area of the revised tombolo occupies about 1.5 hectares less than the original design, thus reducing the loss of natural sea bed by about 15 per cent. The remaining conclusions of Section 16.3 of the EIS still apply.

1 16.3.1 Simpsons Bay and Gunnamatta Bay

The assessment of impact is largely the same as for the original appendix

I report. However, the wider channel under the revised tombolo design will require more dredging in the main entrance channel to the estuary and across Gunnamatta Bay, and will lead to the retention of the middle

I ground shoal in Simpsons Bay.

In the EIS studies, the benthic communities occupying the middle ground were relatively depauperate, compared with the entrance channel. In I particular, there were significantly more invertebrate species and a higher abundance of crustaceans in the channel site compared with the middle ground. Thus in the short term, increased dredging of the channel

I will cause a greater loss of benthos than under the original proposal. In the long term, however, recolonisation of the channel floor will occur, and the middle ground shoal will become stabilised. As a stable shoal, the middle ground may support seagrasses and associated fishes such as I leatherjackets, or it may remain unvegetated, supporting whiting, flathead and flatfishes.

1 The retention of the middle ground would probably restrict access of large powerboats and deep-keeled sailboats into Simpsons Bay. If this restriction reduced the likelihood of boats mooring in the Bay for long

I periods or overnight, it would also reduce the likelihood of boat discharges being disposed of in Simpsons Bay.

I The increased width of the channel entrance may have less impact on the movement of organisms into and out of the estuary than the narrower channel originally proposed. The entire channel would be less susceptible

Ito beach seining from Salmon Haul Bay. Moreover, the zone of separation along the training wall will provide an alternative passageway (with much reduced current velocities and slightly shallower water depth) along which fish may migrate.

I Ll

1 planning workshop 17

I

16.4 Rocky Shores and Reefs

16.4.1 Simpsons Bay and Gunnamatta Bay

As per the original report, with the following exceptions:

The tombolo training wall will be about 15 metres shorter, causing a small reduction in the amount of sea wall available for colonisation by intertidal and subtidal organisms.

The zone of separation detected in the physical model means that very slight currents will impinge upon the tombolo training wall. It is not possible to predict the effect of this on intertidal and subtidal community structure, although there may be some favouring of fragile or weak-swimming organisms, such as small juvenile fishes.

The spur now proposed at Hungry Point will rise only one metre above ISLW, and so will be covered during the upper half of the tidal cycle. The spur itself will support intertidal and subtidal organisms. It is also likely to reduce the degree of exposure to seas and swells along the rock platform to its north. This will, in turn, probably lead to a change in community structure, with species adapted to more sheltered conditions eventually predominating. It is noted that construction of the spur wall will be undertaken from barges rather than by land over the existing rock platform, so minimising the impact to the platform during the construction phase.

16.5 Mangroves, Saitmarshes and Seagrasses


16.5.1 Simpsons Bay and Gunnamatta Bay

Unchanged from the EIS, except that now the middle ground will not be dredged, with less chance of perturbation to the seagrasses now occurring in Simpsons Bay.

16.6 Aquatic Birds, Marine Mammals and Sharks


16.7 Commercial and Recreational Fishing

Unchanged from the EIS, except that if the rock spur at Hungry Point is accessible to shore anglers, signs should be erected, warning that the spur is covered at mid to high tide.



I I Li I Li I I [1 [1 LI [ i I I I I I I I


I 1 17. AIR QUALITY

No change.

18. NOISE

I The effects of the amended proposal upon the acoustical environment have been assessed as follows:

I 18.2 Assessment of Noise Impact from Construction Activities

18.2.1 Dredging

I The proposed changes in dredging activity associated with the construction of the tombolo will result in a 26 per cent reduction in volume of sand to be dredged and a significant reduction in associated

I noise impact. The level of noise generated will not change. However, the period of such exposure would be conservatively reduced by at least 15 per cent.

I The dredging associated with the channels will be reduced by 600 cubic metres (-8 per cent) at the entrance to Gunnamatta Bay; will increase by 85,000 cubic metres (+48 per cent) across Gunnamatta Bay; decrease

I by 6,000 cubic metres (-10 per cent) south of Burraneer Bay; and result in a cumulative reduction of dredging of approximately 23 per cent overall.

I The acoustical variance of these activities is thus regarded as offering an overall environmental acoustical benefit, even though the dredging noise activities are not the most significant activity associated with the

I proposed Waterway Improvement Works.

18.2.2 Trucking Operations

1 No change from the EIS, as traffic volumes are essentially unchanged.

I18.2.5 Construction of Sand Tombolo

Essentially unchanged from the ETS. It should be noted that the construction period of the tombolo has been extended by four weeks, and

I the direction of dredging activity in the lower estuary has been reduced.

18.2.6 Construction of Hungry Point Spur Wall

I The proposed construction of the Hungry Point spur wall will involve the provision of 4,000 tonnes of five tonne rock utilising a barge-mounted

I crane to place the material. The rock will be delivered by truck to a barge which will operate between the end of the tombolo site and the proposed Hungry Point spur wall.

I I


I I These trucking operations are regarded as the most significant segment

of the spur wall construction phase, as the placement of rock from the barge will take place at a location which is relatively free of residential

I development and shielded from that residential development by parkland at the end of the point.

I The construction of the proposed spur wall will involve approximately four weeks of activity and based on the data provided, should not result in any significant increase in total vehicular traffic for rock haulage operations, when compared with the original rock haulage requirements

I specified for the original proposal.

The noise generated by the use of a tug and associated barge for the

I placement of the rock at Hungry Point will produce a "just audible" noise component at Hungry Point, and a generally inaudible increase in noise level at Burraneer Point.

1 18.3 Assessment of Impact

I The acoustical assessment of the revised works associated with the construction of the Port Hacking tombolo, associated dredging works and the revised proposal for the construction of a spur wall at Hungry Point should not result in any significant change in the level or duration of

I noise making activities which could give rise to an adverse acoustical impact.

I Based on the data received, it is considered that the conclusions drawn in the EIS remain unchanged as a result of the proposed revisions to the scheme, and that the noise generated by the revised proposal will also conform to the latest environmental criteria recommended by the State

I Pollution Control Commission for major public works.

I 19. VISUAL IMPACT ASSESSMENT

I Changes as outlined below.

19.1 The Impact of the Tombolo and Spit on the Physical Features of Port

I Hacking


1 19.2 Views, Viewpoints and the Visual Impact of the Tombolo and Spit


19.2.1 Lilli Pilli Spit


19.2.2 Cabbage Tree Point Tombolo


I


View 3 from Shiprock Road, Turriell Point


View 4 from Darook Park

Essentially unchanged from the EIS. It should, however, be noted that the structure is further away from Darook Park due to the amended proposal.

View 5 from Bundeena Point

View marginally altered. Visual impact remains as described.

View 6 from Cabbage Tree Point (see Figure 19.10a)

I

View marginally altered. Visual impact remains as described.

View 7 from Pacific Crescent (see Figure 19.11a)

I Essentially unchanged from the EIS. Due to the amendments, the tombolo will become an interesting middleground focus as it continues the sweep of Simpsons Bay enclosing and defining this body of water

I without isolating the Bay from the lower reaches of Port Hacking. The mass of water gives continuity to the view as it links the foreground to the horizon.

I Therefore, whilst the tombolo reduces the visual quality of the views from Pacific Crescent, the views will still hold great visual appeal.

IView 8 from Burraneer Point (see Figure 19.12a)


I The construction of the tombolo will not impact this background view but will change the way that the southern headlands of Cabbage Tree Point,

I Bundeena Point and Port Hacking Point gradually rhythmically and sequentially enclose this water body. Whilst maintaining an open body of water between Hungry and Bundeena Points (and therefore to the horizon), the tombolo will define two smaller bodies of water, Simpsons

I and Bundeena Bays and create a more detailed foreground and middleground view. From this position, the rock training wall is clearly visible, providing a rigid termination of the tombolo. This is offset by other features of the tombolo which are of visual merit, such as the I vegetation growing on the dune and the pocket beach on the western side of the tombolo.

I View 9 from Woolooware Reserve


I View 10 = Aerial View

View altered. Visual impact remains as described.

I I I] 1 I I I

I


I 19.2.3 Summary of Tombalo View Assessments

I


19.3 Temporal Changes




The construction of the Hungry Point spur wall will have an insignificant

I impact upon the visual environment.

I TRAFFIC AND PARKING

I 20.1 Construction Impact

Unchanged from the EIS. The traffic volumes during the construction

I period are unchanged.

20.2 Increased Attraction on Completion

I Essentially unchanged. There may be a marginal reduction in the number of visitors who would use the tombolo as a result of its reduced length. However, this reduction is unlikely to affect the overall increase in

I visitation to the Bonnie Vale area of between 5 and 10 per cent.

I IMPLICATIONS FOR TEE ROYAL NATIONAL PARK

1 21.1 Impact of Increased Road Traffic Upon the Flora and Fauna in the Royal National Park

I Unchanged from the EIS. The amount of traffic passing through the Royal National Park during the construction period is unchanged.

1 21.2 Effects on Park Visitors Generally


1 21.3 Effects on Bonnie Vale

I 21.3.1 Short Term Effects

Essentially unchanged, although it is to be noted that the construction period for the tombolo sand body is now 39 weeks.

I I


I 1 21.3.2 Long Term Impacts

Increased Visitation

I Essentially unchanged from the EIS, although the decision not to dredge Simpsons Bay may mean that fewer visitors arrive at the tombolo by

Iboat. Refer also to Section 20.2 above.

21.4 South West Arm

I No change.

21.5 Implications for the Plan of Management

I No change.

I

21.6 Tombolo Plant Species

No change.

I 1 22. IMPACTS ON LAND AND WATERWAY USE

22.1 Impacts on Adjacent Land Use

1 22.1.1 Cabbage Tree Point

Essentially no change in construction impacts, although the construction

I period for the tombolo sand body is now 39 weeks.

Essentially no change to visual impacts.

I It is expected that there may be a slight decrease in the visitation rate from the numbers stated in Section 20 of the EIS.

1 22.1.2 Hungry Point

The construction of the spur wall off Hungry Point will have no effect on

Iexisting land use at Hungry Point,

It was also determined from the archaeological survey that the proposed

I spur wall would have no significant effect upon the archaeological environment.

I 22.2 Impacts on Waterway Use

Essentially no change.

I22.2.1 Use of Foreshores

Essentially no change.

I I


I I 22.2.2 Informal Use of the Waterway Sailboarding and Surfing

I extend As a result of amendments to the design of the tombolo, it will now

some 400 metres into the waterway (as opposed to 500 metres), and will occupy an area of 8.5 hectares, as opposed to 12.0 hectares, as originally proposed.

I This will mean that the reduction in the area of the waterway available for recreational boating will be less than that originally proposed. It will also mean that there will be a minor reduction in the extent of wind I shadow in the lee of the tombolo, consistent with the length of the tombolo.

I There is now no proposal to extend the dredging into Simpsons Bay, and therefore, this Bay will remain inaccessible to deep draught vessels.

I The nett effect of these changes is that the existence of the tombolo will improve the potential of the foreshores to be utilised for passive recreational use, and whilst there will still be an impact upon the waterway for uses such as sailboarding and surfing, this impact will be I less than under the original proposal. Furthermore, the restriction of dredging to areas outside Simpsons Bay (thus excluding deep draught vessels) will ensure that there is no conflict of interest between active

I and passive recreational users in this part of the waterway.

22.2.3 Recreational Boating

No change.

I Simpsons Bay will be inaccessible to deep draught vessels.

22.2.4 Commercial Boating

I No change.

22.2.5 Demand for Additional Recreational Boating Facilities

I No change.

22.3 Recreational Use of the Proposal

I Essentially unchanged from the ElS.

I 22.3.1 Benefits of the Tombolo

The benefits of the tombolo are essentially the same as under the original proposal. However, the impacts of the tombolo on the existing I users of Simpsons Bay will be slightly less than under the original proposal.

I I I


I 1 SOCIO-ECONOMIC IMPACTS

I 23.1 Public Participation in the Project

The PWD has been committed to complete community consultation and participation during the planning of this waterway improvement project.

I The amendments to the original proposal, as detailed in this addendum, have been devised firstly due to design considerations, but also having regard to the public responses to the various displays and exhibitions of I the proposal.

23.3.1 Community Responses

I Section 23.3.1 of the EIS lists the perceived disbenefits that the community feels would result from the tombolo.

I The proposed amendments would ensure that the resulting impacts of the proposal are less than originally proposed upon the following issues:

I * wind shadow in the lee of the tombolo; and * reduction in area of waterway;

I For these reasons, and the fact that the tombolo as amended is now a substantially smaller structure, the proposed amendments should result in the proposal being more acceptable to the community.

1 23.5 Economic Considerations


SUMMARY OF ENVIRONMENTAL SAFEGUARDS

I

Changes as outlined below.

24.1 Dredging

I The decision not to dredge south of the Burraneer Point channel will help ensure the preservation of existing seagrass meadows in Simpsons Bay.

I

24.2 Navigation

A navigation light should be attached to the Hungry Point spur wall to

I

ensure that it will not pose a hazard to vessels in this part of the estuary.

24.3 Air Quality


I

I


planning workshop

01

24.4 Water Quality


24.5 Road Traffic Through the Royal National Park

Unchanged from the ElS.

24.6 Effects on Bonnie Vale


24.7 Noise

Unchanged from EIS.

24.8 Marine Life

Unchanged from the EIS, except that in addition to the recommendations previously made, the possible utilisation of the zone of separation along the tombolo training wall by fish and invertebrates be examined as part of any monitoring programme on the effects of the tombolo. This should encompass the possible movement of fish into and out of the estuary via the zone; and the structure of communities living on and around the artificial reef of the training wall.

24.9 Visual Impacts


24.10 Facilities


25. CONCLUSIONS

Conclusions relating to all aspects of the environmental impacts of the proposal have not been significantly altered, following the amendments to this proposal. The overall conclusions of the EIS are therefore unchanged.

I planning workshop

I I I I I I I I

APPENDIX A

I

TABLES AND FIGURES

I I I I I I S I I I

Appendix A - Table 1: Changes to Tombolo Design

Principal Changes

Original

Amended

Tombolo Sand Body


planning workshop

Across Ounnamatta Bay

South of Burraneer Bay

Mouth of Burraneer Bay

- area - volume - width - depth




- area - volume

- area - volume

- 5 tonne - 0.5 tonne - quarry run Total

500 m 570,000 m3

6.0 m ISLW 10 ha

4.6 ha, 76,000 m

40 m 4.0 m ISLW

15.8 ha 175,000 m3

130 m 4.0 m ISLW

5.7 ha, 66,000 m

100 m 3.0 m

4.2 ha, 32,000 m >

100 m 3.0 m ISLW

45.3 ha, 5701000 m2'

51.9 ha, 640,000 m

240 m 70 m

6.0 m ISLW 4.5 m ISLW

20,000 tonnes 71000 tonnes

22,000 tonnes 49,000 tonnes

400 m 420,000 m3

6.5 m ISLW 8.5 ha

4.2ha, 70,000 m

40 m 4.0 m ISLW

24.2 ha, 260,000 m

240 m 4.0 m ISLW

5.5 ha, 60,000 m

100 m 3.0 m

4.2 ha, 32,000 m

100 m 3.0 m ISLW

38.1 ha3 422,000 m

44.7 ha, 493,000 m

225 m 70 m

6.5 m ISLW 3.5 m ISLW



Length Volume of sand Maximum height Area

Channel Dredging

Into Ounnamatta Bay

Total lower estuary

Total (lower estuary and Lilli Pilli)

Rock Supply

Tombolo Trainina Wall

Length Length of single faced wall Maximum height Minimum height Rock quantities:


planning workshop

Appendix A - Table 1: Changes to Tombolo Design (cont'd

Principal Changes Original Amended

Hungry Point Spur Wall

Length 50 m

Maximum height 1.0 m ISLW

Minimum height 0.0 m ISLW Rock quantities: - 5 tonne 4,000 tonnes

Total: (training wall, spur wall and Lilli Pilli)

Quantity - 5 tonne 20,000 tonnes 22,000 tonnes - 0.5 tonne 7,000 tonnes 6,000 tonnes - quarry run 22,000 tonnes 21,000 tonnes - gabion rock 2,000 tonnes 2,000 tonnes Total 51,000 tonnes 51,000 tonnes

Trucking

No. trips/week - 5 tonne 54 58 Duration 25 25

- 0.5 tonne & 62 58 - quarry run 25 25 - road base 12.5 12.5 - gabion rock 3 3 - 25 25 - peak 128 128 - 25 25

Construction Programme - Lower Estuary

Large dredge 18 17 Small dredge 26 6 Sand body profiling 35 17 Training wall construction 30 28 Spur wall construction 4 Landscaping 12 10

Total 50 48

Energy Consumption 15 x 106 MS 15 x 106 MS


planning workshop

Appendix A - Table 8.1: Port Hacking - Dredging in Lower Estuary - Dredge Depths, Plan Areas and Volumes

Location Dredge Depth

(metres below TSLW)

Estimated Dredge Plan

Area (hectares)

Estimated Dredge Volume

(cubic metres)

Navigation channel into 4.0 4.2 70,000 Ounnamatta Bay

Navigation channel at mouth 4.0 24.2 260,000 of Gunnamatta Bay

Burraneer Point channel 3.0 5.5 60,000

Navigation channel at mouth 3.0 4.2 32,000 of Burraneer Bay

Total 38.1 422,000

Source: Patterson Britton and Partners

I I I I I I I I I I I 1 I I I I I I I I

planning workshop

Appendix A - Table 11.1a: Anticipated Traffic Movements

Activity

Estimated Duration

(Weeks)

Estimated Number of

Vehicle Trips Per Week

Anticipated Vehicle

Type

Engineering Works

Establishment and 5 10 15 tonne flat bed disestablishment trucks

Delivery of site consumables 52 8.5 10 tonne trucks

Delivery of quarry rock: - Primary armour layer * 52 58 20 tonne trucks - Underlayer and quarry run * 25 58 20 tonne trucks - Lilli Pilli rock * 25 3 20 tonne trucks - Road base * 8 12.5 20 tonne trucks Workforce daily travel 52 100 Passenger vehicles

and light trucks

Landscaping Works **

Delivery of Botany Humus 12 30 15 tonne trucks

Delivery of landscape supplies 10 3.5 10 tonne and light trucks

Landscaping workforce 12 25 Passenger vehicles and light trucks

Source: Patterson Britton and Partners/Conybeare Morrison and Partners

Note: * Vehicle trips expressed as round trips ** Landscaping works to commence one or two months after completion

of engineering works, depending on soil conditions. Botany Humus to be delivered during year 2 of planting programme.

I I I I I I I I I I I I I I I I I 1 I I

Appendix A - Table 14.3a Port Hacking

MEAN WAVE HEIGHTS (m) FROM PHYSICAL MODEL

POSITION *

PRE- POST- N UMBER TOMBOLO TOMBOLO

1 2.9 2.9

2 1.8 2.2

3 1.7 1.8

4 2.7 2.5

5 1.7 1.8

6 1.8 1.0

7 1.2 0.8

8 0.6 0.4

9 0.6 0.1

10 0.7 0.4

11 1.3 0.1

12 0.4 0.6

13 0.7 0.4

* Refer to Fig. 14.3a for location of probes

extent of dredging

training walls I groynes

TP0RT HACKING TOMBOLO E.I.S.

I SITE PLAN 12C1

1km ,

I Note: This site plan shows the site for the proposed works as amended in this

addendum. It supersedes the site area shown on all plans in the EIS.

I I

Prepared by PLANNING WORKSHOP

For PUBLIC WORKS DEPARTMENT

A I I I I I I I I I I 1 I I I I I

Sydney County Council Submarine Cable (11 kv)

Sydney County Council Overhead Cable (11 kv)

Telecom Australia Submarine Cables

Public Works Dept. Data Collecting Equipment:

submersible current meter A wave I tide pole & current meter

N.S.W. Maritime Services Board Channel markers

r PORT HACKING TOMBOLO E.I.S.

SER VICES 1.5a AND STRUCTURES

0 1km%

Prepared by PLANNING WORKSHOP For PUBLIC WORKS DEPARTMENT


Uj

WuHg LILLI

KSHlRAV , Point 80

BA R :T~H ACKl9 z

GROYNE-

\ I)

Simpsons

\ Bay

\ L —

I/v

CONSTABLES POINT

BONNIE VALE

ROYAL NATIONAL PARK

j5 t ALL DIMENSIONS ARE IN METRES UNLESS NOTED OTHERWISE

2 ALL DEPTH CONTOURS AND DREDGE LEVELS ARE IN METRES BELOW INDIAN SPRING LOW WATER (ISLW)(FORI DENISON) HEIGHTS ABOVE ISLW ARE PRECEDED BY A PWS SIGN

I DEPTH CONTOURS ARE BASED ON 1978 PUBLIC WORKS DEPARTMENT PORT HACKING HYOROGRAPHIC SURVEY

. ALL DREDGE SLOPES ARE 1.5 (VERTICAL HORIZONTAL) MAX. EXCEPT AS NOTED

LEGEND

DREDGE RL.--O

DREDGE RL.-30

DREDGE RL.20

NAVIGATION CHANNEL DREDGE RL-l.O -

Gunnamatta Bay

/ 2

f1

BURRANEER

BASS & FLINDERS POINT ._•-

' HUNGRY Wa SPUN w*JL POINT

J

IANNL

0 A GFRONTO 1RAINIG WALL IS I VERT 1)AiL

Haut Bay

/

(epared by PLANNING WORKSHOP For PUBLIC WORKS DEPARTMENT

'N

Lt,-

Bundeena Bay

/ PORT HACKING TOMBOLO E.I.S.

DREDGING PLAN 8.1a SHEET 1

•1

CABBAGE TREE POINT

I

I

L I MO I ~51

L

\Oo(an.'\

C) I

BAH'r

LITTLTLRRIELL

CARING

I —•-- POINT

I A7 i ...

NNJIGATION CHANl\ DREDGE RL -30 T.

I ,1

'L 'r\\

NAVATION CHANNEL DREDGE RL30

BURR ANEER POINT

Iz

2

j A

UN A

Cb/

_ 24

/1 1 ?) L(

1LJ \\ I

/J 2

( BURRANEER

GOGERLYS POINT POINT ——o---

0 Dee oan I \ 0,

soit Ad i \ /

\ C4 \

\ CONSTABLE'S POINT I COSTENS

POINT

I Simpson's

Boy

I NOTES - 1 FOR CROSS SECTIONS SEE FIGURES

I 2 ALL DEPTH CONTOURS AND DREDGE LEVELS ARE IN METRES

TO INDIAN SPRING LOW WATER (ISLW) (FORT DENISON) UNDERLINED FIGURES ARE DRYING HEIGHTS ABOVE ISLW

I 3 DEPTH CONTOURS ARE BASED ON 1978 PUBLIC WORKS

DEPARTMENT PORT HACKING HYDROGRAPHIC SURVEY AND LEGEND 1979 AND 1984 PUBLIC WORKS DEPARTMENT HYDROGRAPHIC SURVEYS BWEEN LILLI PILL) POINT AND GOGERLYS POINT DREDGE AREAS

I TRAINING WORKS

0 250 50Dm

I

CABBAGE TREE POINT

Bundeena Boy

N 2

PORT HACKING TOMBOLO E.I.S.

CROSS SECTION 8.3a LOCATION PLAN

(epared by PLANNING WORKSHOP PUBLIC WORKS DEPARTMENT

I I I I I I I I [1 I

3URRANEER

MT

I I I I I I I I I I I I 1 I I I I I I 1

+

+15 CABBAGE TREE POINT PROPOSED TOMBOLO CREST VARIES LINEARLY

ISLW 0

50 100 150 200m -10 I

SECTION 4-CABBAGE TREE POINT TOMBOLO AND NAVIGATION CHANNEL AT MOUTH OF GUNNAMATTA BAY

IDIST0RTED SCALE (Si VH1

+15

+10

BU RRANEER

+5 CHANNEL PROPOSED NAVIGATION

MEAN WATER LEV

ISLW 0

-5

0 100 150

Om -10

SECTION 5 - NAVIGATION CHANNEL INTO GUNNAMATTA BAY IDIST0RTED SCALE (5:1 V:HI]

SOURCE:PATTERSON BRITTON AND PARTNERS

SECTION 3-EXISTING NAVIGATION CHANNEL AT DEEBAN SPIT

[DISTORTED SCALE (5:1 V:H)I

PROPOSED NAVIGATION CHANNEL

HUNGRY POINT

EAN WATER LEVEL

1

CR0 NULL A

NOTES FOR LOCATION OF SECTIONS SEE FIGURE

ALL DIMENSIONS ARE IN METRES UNLESS NOTED OTHERWISE.

ALL ELEVATIONS ARE TO INDIAN SPRING LOW WATER (ISLW)

r PORT HACKING TOMBOLO E.I.S.

TYPICAL CROSS SECTIONS 8.4 a OF LOWER ESTUARY WORKS

Prepared by PLANNtNG WORKSHOP For PUBLIC WORKS DEPARTMENT

I

I

I ROCK ARMOURED ---

I ijRAINING

I /

/

WALL-

ROCK GABION GROIN

I

I NOTES 1. ALL DIMENSIONS ARE IN METRES UNLESS

2 ALL DEPTH CONTOURS AND DREDGE LEVELS \ NOTED OTHERWISE

ARE H METRES TO INDIAN SPRING LOW

I

WATER (IsLw) FORT DENISON 3 DEPTH CONTOURS ARE BASED ON 1978

PUBLIC WORKS DEPARTMENT PORT HACKING HYDRODRAPHIC SURVEY

4. FOR TRAINING WALL CROSS SECTIONS REFER \ \ FIGURE 9.3.

1 0 50 lOOm

\ SCALE

I BOARD AND CHAIN WALKING TRACKS (TYPICAL)

I /1

TOMBOLO SAND BODY--- /

DREDGE AREA

/ j,'OMAPOORARY

ACCESS /

I

EXISTING TREES

EXISTING RANGERS RESIDENCE

1

L\ \ \\\ \\\\\\

\ \ rn

\\ r I \ \\ \ \

\\ \

\\\

& \\ \

CABBAGE TREE POINT

CRAMMOND UEf

.

PORT HACKING TOMBOLO E..I.S.

9.la TOMBOLO AND TRAINING WALL PLAN CONFIGURATION

Prepared by PLANNING WORKSHOP :1 \\ C SOURCE

For PUBLIC WORKS DEPARTMENT PATTERSON, BRITTON & PARTNERS PTY LTD.

___________________________________________________________ /1

TYPICAL SECTION THROUGH RUBBLE MOUND WALL

CREST EL .65

—E-

QUARRY ~6N

7FILTER J FABRIC

QUARRY RUN

5 TONNE ROO< ARMOUR

UNDER L A YE R

05 TONNE

TYPICAL SECTION THROUGH ARMOURED SLOPE

i

4-Om

EL .1.0

5 TONNE ROCK ARMOUR

TYPICAL SECTION THROUGH SPUR WALL

NOTES

ALL DIMENSIONS ARE IN METRES UNLESS NOTED OTHERWISE.

ALL ELEVATIONS AE IN METRES TO INDIAN SPRING LOW WATER (ISLW).

0 5 10


TOMBOLO TRAINING WALL 9.3a TYPICAL CROSS SECTION

SOURCEPUBLIC WORKS DEPARTMENT


U N DERL AY ER 0 5 TONNE

EST EL.L.5

L.2O I QUARRY RUN

rIv

CORE

I I I I I I I I I I I I I I I

I 1 I I I

5 TONNE

7

6

5

4

3

2

JSLW 0

-2

-3

4

10 20 30 40 50m

Simpsons Bay

10 20 30 40 50m


Simpsons Bay 45m 30m 15m 25m

EL. .6.5

MEAN HIGH WATER LEVEL

EXISTING SEA BED

(EL. VARIES)

TOMBOLO TRAINING WALL

LONGITUDINAL SECTION

DISTORTED SCALE VEP. 1:200 HOR, 1:1000f

TOMBOLO TRAINING WALL

LONGITUDINAL SECTION

UNDISTORTED SCALE 11000

EL. .3.5

Bundeena Bay

EL. • 4.5

N OTES

ALL DIMENSIONS ARE IN METRES UNLESS NOTED OTHERWISE ALL ELEVATIONS ARE IN METRES TO INDIAN SPRING LOW WATER(ISLW) TRAINING WALL UNDERLAYER AND QUARRY RUN CORE OMITTED FOR CLARITY. SECTION SHOWN IS MAXIMUM CREST ELEVATION

Bundee na Bay

PORT HACKING TOMBOLO E.I.S. 1 TRAINING WALL 9.4 a LONGITUDINAL SECTION

I'** j


NOTES

Gunnamatta Bay

I

I .. . PORT HACKING

I' ":.'-. IIINCRY POINT

Hungry Point

SPUR WA!.!

VANTAGE POINT Tl.Om vt tends into the bay.

:7. Flat viewing platform

:'• ,,' .•. BEACH 'N

sandstone rocks (3.5-6.Sme*res

I ' . Small. enclosed sandy beach. mis gives the tornboi Tom bob above ISLW) which simulate iwrowiding iaadstoue cliffs.

-,---

.

,.. .

,, . extra interest, and provides the visitor with a sense of - Dotted lines indicate rocks which fraits pat of theVaáiag wail SUT)flSC and discovery. but extend up to ISLW oedy. The rocks form an imposla.( focal

- :'; ' ROCKY POINT point from Hordens Beach, Hungry Point and Burraaccr Point

I .. D a -' Spit Retains the beach, and crcatesafocal point from . 5 . Simpsons Beach. (Arouses curiosity). '•' S

BEACH • : ,, EvenFy graded (150) protected sandy beach : getated d inkcnuc

SPI

Timber paths 1iWk the beaches over e dune.Sceda<T

TEMPORARY ROAD Road to be used for '. BEACH

. Evenly graded (150) sandy beach. SIGNPOST

' \\ Timber signpost erected at entry to tombolo a (no structures or services) Endemic

\\ The existing pathway is rened at the base of the cliffs

.ANDS704E WALL 7 5 Timber signpost erected at entry point Ic, tombolo. The smooth hoe of the beach begins at the existing

CONCEPT The torsbo&o shall be constructed tt appear as though it was pal of Port Hacking landscape. it will look le a vegetated itlind which has been oined to the mainland by a spit which has

assumed the shape of a foredun

USI The tombolo shall be used for swimming, sunbaking, wailing, fishing and picknicking. it also provides unsurpassed views up and down Port Hacking. The tombolo extends the cun'ent recreational use of Simpsons and Hordens Beaches.

PLANTING The tip of the tombolo shall be vegetated with trees and shrubs to give the effect of an island. The height of the trees will provide a visual link back to Cabhsge Trme Point, at the same time providing the kaaboto with a focal point adding isisaresit to the soinbolo. 1 dune will be planted with grasses and which will protect it from erosion. Trees will be planted at the base of Cabbage Tree Point, providing visual continuity between the nsanIand and the tombolo. All sboabs and Bee species shall be coastal vegetation, native to the area Planting shall be staged over 3 years, allowing 2-3 years for establishment of pnmary species (grasses and creepers), 2 years of secondary species (shrubs and short-lived trees) with tertiary species (trees) being planted in the third year. Planting shall be fcrtilised and regularly maintained.

PROTECTIVE FENCING Fencing shall be erected arounti all planted areas, providing protection to the dune and the plants. Fencing shall be treated pine posts and rails with hinge joint wire between posts.

PATHS Paths over dunes shall be timber slatted boards bolted to galvpsised chain.

Isandstone

- •:

.. , wall - -

1

"

ON beach extended past clff to run full Nin ibito of the tombolo.

Gunyah c

pson's Beach Hordens Beach

2

i

Bonnie ae $ / 1 7/

a

1 N '•\

S - S

-, \ • N '\ \\

':'\

N ROY


9.5a

/ LANDSCAPE MASTER PLAN

75 #1%

Piopared by COY8€AE MQRSON & PAS For PUBLIC WOflXS OEPAATMEHT

I

5 .-,.

MONTHS

TASK 1 2 3 4 5 6 7 8 9 10 11 12 13 14

LOWER ESTUARY TRAINING WORKS

DREDGE NAVIGATION CHANNELS AND WATERWAY AREAS:

LARGE DREDGE OPERATIONS

CONSTRUCT TOMBOLO ROCK WALLS

LANDSCAPE TOMBOLO

LILLI PILLI TRAINING WORKS

DREDGE NAVIGATION CHANNELS

CONSTRUCT LILLI PILLI SPIT

SAND BODY

GABION WALLS

SMALL DREDGE OPERATIONS

CONSTRUCT TOMBOLO SAND BODY

-

—

I I I

PORT HACKING TOMBOLOE.I.S.

1 PRELIMINARY I I.ICI CONSTRUCTION PROGRAMME

fepared by PLANNING WORKSHOP (For URUC WORKS DEPARTMENT

P

I I I I I 1 I I I I I I I

I ENGINEERING WORKS: Distribution of Traffic Movements over Construction Period

Truck Movements

Establishment and 2.5weeks

disestablishment 2.5 weeks

Delivery of site 52 weeks

consumables

Delivery of Quarry Rock

Primary armour layer 25 weeks_ - 25 weeks Underlayer and quarry run - - 25 weeks Lull Phil rock Road base S weeks

Light Truck Movements and Passenger Vehicles

Workforce Daily 52 weeks Travel

1 I LANDSCAPING: Distribution of Traffic Movements

over Initial Landscaping Period

I Months Activity

1 2 3

I I

INote: Landscaping works commence 1-6 months after engineering works are completed.

1 I


DISTRIBUTION OF 1 i.2a TRAFFIC MOVEMENTS

Prepared by PLANNING WORKSHOP

For PUBLIC WORKS DEPARTMENT

Activity Months

1 2 3 4 5 6 7 8 9 10 11 12

I I

I I

Truck Movements

Delivery of Landscape Supplies 1 weeks - Light Truck and Passenger Vehicles

Landscaping workforce

12 weeks

7-7

1 1 I

- - - - - - - - - - - - - - - - - - - - rn

I

(i1 / ir rn

rn

\BURRAEERNT HUNORY POINT _ • - 13 12 1 . 7

----- ------ 6

11 1 CD I - -

1 - REFERENCE - POSI ION pom cl

7 rn

__ —1 . \ - (,1 -r-----&------ \ \H

CD

(D

REFERENCE PHOTOGRAPH

1I&.

&t.•

'IL...

If •. irJ&

t•;P.; '

3: * I,

h

2JL 1 -, --------..--

/

1 yi

VIEW 6: View to Gunnamatta Bay from Cabbage Tree Point.

f•',' .'-•

'4T'

I VIEW 8: View to Cabbac Tree Point from Burraneer Point. LF,rParedbYGONYBEAMORON & PARTNERS1 9.1 2aj

NEW SOUTH WALES PUBLIC WORKS EI5

53 11

Part Hc L. kr Tbio addndw

4LS LBLiC W r5 E TS

Port Hackrq Toinboic ddendui

Errowers nd

MCOO

EIS 531 ABOI 8625 Port Hacking tombolo : environmental ...

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