EIS 827

AB019551

Proposed maintenance dredging of : review of

environmental factors I V uFH] OF /'\ :'tRGY I ABO 19551 I II I COUNCIL I I Li..] MAI1fl'ENANCE DREDGING OF PORT HACKING I I I REVIEW OF ENVIRONMENTAL FACTORS I I

S. MANWARR INC JANUARY, 1990

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I EIS 827 I have examined this environmental review report and agree that the project does not have a significant impact on the environment and that work can proceed.

E. Sang,(/ (Acting) Director - 1!'echnical Services.

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PROPOSED MAINTENANCE DREDGING H OF PORT RACKING REVIEW OF ENVIRONMENTAL FACTORS

Table of Contents I This report has been presented under the following headings: Purpose of the Report I Outline of the Proposal The Need for the Dredging Proposal I 3.1 The Existing Environment 3.2 Management Options I 3.3 Consultation with Relevant Authorities Local Planning Instruments and Zoning Assessment of Environmental Impact of the Proposal 5.1 Visual Amenity 5.2 Acoustic Environment 5.3 Air Quality 5.4 Water Quality I 5.5 Marine Flora and Fauna 5.6 Tidal Hydraulics 5.7 Public Amenity I' Consideration in Accordance with Clause 56 of the Environmental Plannning and Assessment Regulation I Conclusion References

Figures

Fig. 1. Nominal Areas of Proposed Dredging and Surrounding Environs I

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1. PURPOSE OF THE REPORT This report has been prepared to document the examination and consideration of matters likely to affect the environment arising from the proposed dredging of the navigation channels in Port Hacking from the Cronulla Peninsula to Gogerlys Point and into Gunnamatta and Burraneer Bays as required by Section 111 of the Environmental Planning and Assessment Act (as amended). A conclusion is reached as to whether the proposal is considered likely to significantly affect the environment, pursuant to Section 112 of the Act. 2. OUTLINE OF THE PROPOSAL It is proposed to dredge sections of the existing navigation channels in Port Hacking in order to maintain safe navigation along this waterway for boating access and improving boating safety. The movement of large quantities of sand within the under the action of tide and wave has caused infilling of these channels. For many years dredging has been undertaken in Port Hacking to alleviate this ongoing problem. Sutherland Shire Council is investigating possible long term solutions to this siltation problem. In the meantime, sections of the existing navigation channels have shoaled to the point where maintenance dredging is again required. This situation has been brought to the attention of Council by local residents and users of this estuary and the Department of Public Works has made funding available to carry out this urgent work. The proposal would involve dredging predominantly through sand at the locations depicted in Figure 1. Sites located within and south of , south of Burraneer Point and within are to be dredged to a depth of 2.5 metres below Indian Spring Low Water (ISLW) for a channel width of twenty five metres. Sites west of "Shiprock" at Little Turriell Point to Gogerlys Point are to be dredged to 2.0 metres below ISLW for a similar channel width. Dredging adjacent to Bundeena Wharf would be to a depth sufficient to accommodate the Cronulla to Bundeena Ferry Service. I

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The dredge would pump the sand spoil through a water-tight floating or submerged pipeline to the proposed disposal areas shown in Figure 1. Piping distances would be kept to a minimum and sand from a specific channel would be deposited in the closest convenient and suitable disposal area. The dredged material would be deposited in such I a manner that the reduced level of the top surface of sand is not above 6.0 metres below ISLW. The dredging operation is expected to commence at Burraneer Point progressing eastwards into Gunnamatta Bay and thence westwards to Gogerlys Point. The Bundeena Wharf area would be the last section of channel completed. The construction period is anticipated to extend for approximately six months commencing in early 1990. 3. THE NEED FOR THE DREDGING PROPOSAL 3.1 The Existing Environment Port Hacking is a highly silted estuary extending from the entrancesouth of the Cronulla Peninsula to Grays Point. During the last two million years the sea has fluctuated in level several times, each time drowning a large portion of the river valley with marine I water. The slow flooding was also accompanied by sedimentation as the marine waters, through wave and tidal currents, transported large volumes of sediment back into the drowned valley. At present, the waves and currents prevailing off Port Hacking do not favour the transport of sand into the estuary and the input of this material into the river valley is negligible. However,within the estuary, waves and tidal currents are providing sufficient energy for the redistribution of sediments in a 'continuous attempt to reach and maintain a condition of equilibrium. Shoals and tidal channels are formed and slowly change and shift in response to new conditions. The major elements of the aquatic environment within Port Hacking is dominated by three distinct vegetative habitats characterised by seagrasses, mangroves and saitmarshes. These habitats provide food within the estuarine environment and also sheltered and stable areas for juvenile and adult fauna. Of the three vegetation types seagrasses F Li I

I -4- I occupy the biggest area within the Port, decreasing current velocities, stabilising substrates and improving water clarity and oxygen content. Port Hacking is one of the four major waterways in , its environmental characteristics and location on the boundary of a I major city providing a recreational resource of regional importance. Use of the waters of the Port is almost totally confined to recreational 1 pursuits as the river valley is virtually closed to commercial fishing and there are no commercial shipping functions. A single commuter ferry I route traverses the waterway between Cronulla and Bundeena. General boating use, including fishing, sail and power cruising, waterskiing and so on, is likely to increase in line with the I general trends for greater outdoor leisure activity. If the shoaling problem of navigation channels is not rectified, the increasing I popularity and level of use of the Port will be restricted. 3.2 Management Options I As outlined in the draft "Port Hacking Management Plan ti (March, 1988), management of the shoaling within the Port is a key I element in maintaining an acceptable level of use for the waterway. The Public Works Department in its report on "Port Hacking Marine Delta - Management Options" (1985) outlined a number of options for dealing with [1 this problem involving: No adjustment to the natural process; fl Commercial sand extraction; Training works to stabilise navigation channels; and I Maintenance dredging of the navigation channels 3.2.1 No Adjustment to the Natural Process I This option would involve dredging only to maintain the ferry service between Cronulla and Bundeena. The long term effect of this option would result in the channels across Burraneer Bay and I Burraneer Point becoming nearly unnavigable and susceptible to sudden closure by sand slugs mobilised by wave action during a severe storm. I Fewer boats would be able to use the waterway and there would be no I incentive for development of the area facilities. The channel from I

I I U -5- Gunnamatta Bay to the ocean would be maintained because of the necessity I of the ferry service and there would subsequently be intensive development pressure on facilities within Gunnamatta Bay. I The waterway's existing tourist industry would diminish in the long term and the Port would be virtually unriavigable upstream of Burraneer Point. 3,2.2. Coiimercial Sand Extraction This option would involve the maintenance of navigation I channels either by a commercial sand extraction operation or the removal of large quantities of sand from the marine delta by heavy dredging I plant. The former operation would involve the continuous use of a I small dredge together with barges which would transport sand spoil to a land base somewhere in the estuary or, alternatively, a site external to I the Port. Based on annual dredging quantities of 100,000 cubic metres, a small scale operation may be economically viable however this situation would be subject to the vagaries of the sand market. I Although this type of activity would accommodate an increase in boating within the estuary, its long term profitability is questionable. To date, Sutherland Shire Council's investigations into this type of enterprise has revealed that it would be difficult to obtain a land base within the Port which would be environmentally acceptable to local residents and waterway users. Further, removal of I such a small quantity of sand to a land site outside the Port would more than likely result in unacceptably high production costs. Heavy dredging of the marine delta would involve pumping I or barging the sand to stockpiles in the existing pits at Kurnell. Kurnell is currently one of the main sources of general purpose concrete I and fill sand for the Sydney region. The sand is of a high quality and is easy to extract and for these reasons, no other source of sand in the I area would be economically exploitable until Kurnell closes. Therefore, transporting sand from this river valley to Kurnell is not expected to 1 be an economic proposition until the mid 1990's. (Council has recently called for expressions of interest to further investigate this latter I option.) L I I I

I In addition, untreated Port sands are unsuitable for use in concrete because of their high shell content and require blending I with river sands. Such treatment would further increase production costs. 3.2.3 Training Works to Stabilise Navigation Channels I Two options were proposed by the Public Works Department of for the stabilization of the channels both involving I the construction of permanent training works. One alternative consisted of the construction of a rock training wall projecting approximately one half of one kilometre eastward from the tip of Deeban Spit, together with associated dredging and channel stabilisation works at Lilli Pull. The second alternative also involved stabilisation works at Lull Pilli but replaced the rock training wall at Deeban Spit with a tombolo at Bonnie Vale, which would be formed with sand dredged from I nearby channels and shoals terminating with a rock wall. Works associated with either proposal would concentrate I flows in a restricted channel resulting in an increase in flow velocities causing, in turn, an increase in sand movement and scouring of the channel bed. Sand scoured from the channel would be deposited as terminal bars requiring dredging until equilibrium is reached. Once I this dynamic equilibrium is achieved, the rate of sediment movement and any further shoaling would be greatly reduced. A training wall at Deeban Spit would interrupt the I circulation of sand between the Burraneer Bay shoal and the middle ground shoal resulting in deepening of the area between Cabbage Tree and U Hungry Points and substantially building up Deeban Spit beach. Sand movements onshore and offshore during storms would also be amplified. I On the other hand, the tombolo would stop the sand circulation at Burraneer Point by eliminating waves and strong tidal 1 currents in Simpsons Bay. It would prevent continued erosion of the seaward face of the marine delta eliminating the net sediment feed towards Burraneer Bay over a period of years, thereby stabilising this shoal. The tombolo at Bonnie Vale, the Department's preferred option, Li was withdrawn by the Minister for Public Works following advice that I I I I -7-

I this engineering solution would not have widespread community support irrespective of the outcome of a Public Inquiry. The Deeban Spit I alternative was not pursued further by the Department of Public Works. 3.2.4 Maintenance Dredging of the Navigation Channels The proposed maintenance dredging is expected to be a I "once-off" exercise to expeditiously open existing navigation channels for boating within Port Hacking. It is recognised that a long term I solution is necessary and Sutherland Shire Council has already instigated investigations into commercial dredging of the estuary. I However, it is not expected that any extraction work would be operational until the early to mid 1990's. Dredging of existing channels as outlined in Section 2 I would provide suitable navigational access to boating activity along this waterway for up to three years. Additional dredging may be I required across Burraneer Bay bi-annually and at more regular intervals at Burraneer Point. (The previous dredging of Burraneer Point in early [1 1989 remained open throughout the boating season and well into the latter part of that year.) The position of the bar between the middle I ground shoal and Burraneer Point is the reason for the recurring need to dredge this area because of the associated high levels of sand movement. This alternative is the preferred option at this time. It I will immediately remove the risk of vessels running aground on the sand shoals at low tide and the even more serious problem arising from one or more vessels running aground in an area blocking the way for other craft. Stormy weather exacerbates the risk and increases the danger to Ll vessels and their occupants. 3.3 Consultation With Relevant Authorities 1 Dredging operations to maintain navigable channels within Port Hacking have involved a number of public authorities being F approached in assessing the environmental effect of this type of activity. This consultation procedure has provided an opportunity for the various bodies to make early comment with a view to achieving a mutually acceptable outcome. ri I 11 I I

I These authorities are listed as follows: Department of Agriculture - Division of Fisheries Department of Land I Department of Minerals and Energy Department of Planning I Department of Public Works Maritime Services Board I State Pollution Control Commission Other Authorities I 3.3.1 lflepartment of Agriculture — Division of Fisheries The Department has previously advised that buffer zones are required around aquatic reserves, oyster leases, seagrass beds and I mangrove stands where dredging and disposal operations are conducted on adjoining land. One hundred metres is required to "Shiprock" Aquatic I Reserve, thirty metres to seagrass beds and ten metres to mangrove stands. Oyster leases require a minimum fifty metre buffer zone. Areas I of dredging and sand disposal iiiust be adequately located and policed to ensure that these sites are not significantly altered. Dredging should I also not generally exceed a depth of two metres at mean low water in shallow areas (approximately 2.5 metres below ISLW) to ensure the substrate remains in the euphotic zone to aid seagrass colonisation and I adequate water quality. Existing public access to the estuary foreshore should be provided and the natural undisturbed state of flora and fauna must be maintained. I The Department requires proponents to seek approval from the Division of Fisheries for the proposed maintenance dredging under I the Fish and Oyster Farm Act. According to this authority, large scale dredging is classified as "designated development" under the Environmental Planning and Assessment Act, 1979 and applicants are I required to consult with the Director of the Department of Planning. (As outlined in Section 4, this proposal does not require consent and I consequently falls within Part V of the abovementioned Act. It is I therefore not "designated development" as suggested by the Department). Li I I

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I 3.3.2 Department of Land The Lands Office supports dredging of navigation channels within Port Hacking. The authority recommended that any assessment of the proposal should include possible sale of dredging spoil, location of dispersion sites, affect on the recreational amenity of the Port, I quantity of dredged sand and the asociated alterations to water depths and, the impact of water pollution. I This authority has requested a copy of the review for further perusal and consent. (Council is aware that the sand is the I property of the Crown and as such it will require the permission of the Department of Land to dredge. At the time this permission is sought, a I copy of the review will be forwarded to this authority for its perusal). 3.3 .3 Department of Minerals and Energy The Department considers that the pre-tender estimate of I 74,000 cubic metres of dredged material is relatively insignificant by comparison with the total volume of sand present within the Port, which I probably exceeds one hundred million cubic metres. Although the Council should examine other uses for the dredged material, the Department I considers the quantity involved may not be sufficient to warrant vigorous examination.

The Sydney Regional Environmental Plan No.9 - 'tExtractive I Industry" requires Council to seek the concurrency of the Secretary of the Department of Minerals and Energy. The authority considers that I this concurrency is likely to be granted given the nature of the proposal and the relatively small quantity of sand involved. (As I outlined in Section 3.2.2, the viability of a commercial use for this quantity of dredged sand is highly unlikely for this proposal. However, I should an environmentally acceptable use for this material become available within the duration of the contract, Council will endeavour to I ensure the resource is suitably utilised.) 3.3.4 Department of Planning The Department does not object to the dredging of Port I Hacking, however, several matters require consideration in assessing the I environmental effect of such activities. The review should include a I I I P - 10 -

programme for the proposed operation. Further, an assessment of the noise and visual impact on adjoining residential property should be as well as an investigation of dredging on seagrasses and considered other marine life. Consideration should also be given to alternatives for I disposal of sand spoil in terms of use and location. 3.3.5 Department of Public Works I The Department of Public Works has authorised and provided the funds for the proposed maintenance dredging of Port Hacking. This authority has also contributed to the draft "Port Hacking Management Plan" and has been responsible for reviews of management options within the Port Hacking Marine Delta. In addition, the Department has prepared reviews of environmental factors for dredging at Lilli Pilli Point and Burraneer 5 Point in 1979 and for Cunnamatta Bay and Bundeena Wharf in 1986. (This latter operation was abandoned by the Department.) I This environmental assessment of the latest maintenance dredging proposed within Port Hacking has incorporated relevant I information collated by the Department of Public Works in the abovementioned documentation. (A copy of the review will be forwarded 5 to the Department for its information in due course.)

3.3.6 Maritime Services Board The Board has raised no objection to dredging within Port Hacking provided the operations are carried out in compliance with the I Board's Acts and Regulations. Specifically, these require that the Contractor seeks approval from the authority for mooring arrangements. I Further, all vessels must display appropriate navigation markers and must remove all construction equipment upon completion of dredging. I Damage to existing structures must also be repaired or replaced as required. Regarding the deposition of material within a waterway, I the Board requires provision of details showing water depths before and after dredging to ensure the proposed activity is in accordance with the I submitted application. I I I I

3.3.7 State Pollution Control Commission The Commission has indicated that the disposal of spoil would require licensing under the State Pollution Control Commission Act. Dredging operations would be scheduled under the Noise Control Act and approval under Section 17K of the State Pollution Control Commission Act would be required. Noise control guidelines are contained in the Commission's

I Environmental Noise Control Manual, particularly Sections 20 and 21, which relate to noise level control. The application for approval under I the Noise Control Act should be accompanied by acoustic information and intended measures of control. 3.3.8 Other Authorities Although the adjoins the southern perimeter of the Port Hacking estuary, the National Parks and Wildlife I Service has previously indicated that it was not directly affected by dredging within the river valley. (See Reference 3.) I No other authority was considered sufficiently affected by this proposal for Sutherland Shire Council to seek their early comment. I 4. LOCAL PLANNING INSTRUMENTS AND ZONING The tidal waterway from Port Hacking Point to a point I aligned with Angle Road, Grays Point is zoned 7(a) "Waterways" under the Sutherland Planning Scheme, a deemed planning instrument under the 1 Environmental Planning and Assessment Act, as amended. This Planning Scheme Ordinance sets out the uses or activities which may be undertaken I with the consent of the responsible authority. ' However, pursuant to Clause 83 of this Ordinance, the proposed dredging is a development which does not require consent and consequently falls within Part V of the Environmental Planning and Assessment Act. Sutherland Shire Council is the determining authority I and is also the authority carrying Out the proposed activity. I I I I A

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I This 7(a) ItWaterways lt zoning is also incorporated within the Sydney Regional Environmental Plan No. 9 covering extractive I industries. Clause 11(2) of this Plan stipulates that consent shall not be given to development for purposes other than extractive industries within this zoning without the concurrence of the Secretary, Department I of Minerals and Energy. Therefore, prior to Council consenting to the carrying out I of this proposal, it will be necessary to obtain the concurrence of the aboveinentioned Secretary. I The successful tenderer will also be required to apply for all necessary licenses for this contract under existing legislation, I including the Fish and Oyster Farm Act, the Maritime Service Act, the Noise Control Act and the State Pollution Control Commission Act. 5. ASSESSME NT OF ENVIRONMENTAL IMPACT I OF THE PROPOSAL This section evaluates the likely environmental impacts of I the proposal and describes incorporated safeguards which would be employed during the dredging operation. I 5.1 Wisual Amenity There is an appreciation by the public that views from the I foreshores and from the waterway itself are important in the Port Hacking Estuary. According to the Shanahan Study of residential attitudes to this area (1985), residents considered that the Cronulla I end of Gunnamatta Bay was more built up and less attractive than the Gyinea Bay and Grays Point areas of the foreshore. This easterly portion I of the Port, although less attractive than the more western areas, is still visually prominent from a wide range of regional recreational and I residential locations. Further, both the eastern and western ends of the estuary do have landscaped elements that are appreciated by the I viewer, particularly along the National Park foreshore. The dredging operation of Port Hacking within this scenic environment is expected to last approximately six months and would be I progressively located at various sites within the estuary during this time. It is anticipated that only one dredge would be used in order to I minimise the impact of this proposal. Although the dredging plant would I I I

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I not be visible to a large portion of the Port at any one time, it would be within the vista of residential development predominantly located on I the northern foreshore and also to some areas of recreational use within the Royal National Park. This impact is ameliorated as a result of Port Racking being dredged since the turn of this century and therefore this I type of work is a periodic feature of the waterway's views and vistas. In addition, there appears to be little recorded adverse reaction to the I presence of dredging plant within the estuary. Further, all plant and equipment would be removed from the site and located to another area of I dredging as quickly as possible on completion of the particular channel. The sand spoil would be disposed by discharge into deep holes using a floating or submerged pipeline in accordance with the I requirements of the State Pollution Control Commission. These disposal areas are depicted in Figure 1 and it is noted that piping distances I would be kept to a minimum with sand from a channel being deposited, wherever possible, into a neighbouring disposal area. If in the I unlikely event excessive turbidity is created, screens would be erected around the pipe discharge outlet to suitably reduce this occurrence. Li The dredged material would be deposited in such a manner that the reduced level of the top surface of the material is not higher than six metres below ISLW. I The dredge and disposal pipelines would only incrementally impact on the visual amenity of the Port during the period that dredging I is being carried out. This impact is localised and once the operation is completed in a particular area and the dredging plant removed, the I area would not have been significantly altered visually from its original appearance. 1 5.2 Acoustic Environiint As previously mentioned, the lands adjacent to the sites of dredging and disposal comprise predominantly residential development with housing existing close to the northern shoreline of the Port and also at and Bundeena. It is expected that the acoustic I environment of these residential areas would be characterised by daytime I L90 background noise levels of approximately 45 decibels (dB(A)). I I I

I - 14 - ri Additional incremental background noise can also be expected from weekday boating and other water based recreational activity. Dredging and associated land-based operations would only I be permitted between the hours of 7.00 a.m. and 6.00 p.m. on Monday to Friday inclusive. No work would be permitted on Public Holidays or on I weekends without the prior approval of Sutherland Shire Council. Further, sound created by dredging plant would be restricted to 50 dB(A) at any residential boundary adjacent to a site. Residences in the vicinity of each dredging site would be I subject to a temporary noise impact for short periods only, measured as a matter of weeks. For short term activities, the State Pollution Control Commission guidelines recommend that noise levels should not [ii increase above 20 dB(A) over background levels. It is not expected that this proposal would exceed this limit. I The sound emanating from a dredge may reach a maximum of 90 dB(A) and from a booster pump installation 80 dB(A). Noise is I transmitted clearly across open stretches of water and would be a noticeable but unavoidable aspect of the proposal. Passing water users [1 would experience a degree of this impact, however, it would be of a transient nature and would be significantly nullified by noise created by their own craft. Further, it is anticipated that by dredging I weekdays the impact on surrounding waterway users would be minimised. If justifiable complaints are received about the noise I level from dredging plant, Sutherland Shire Council will undertake to reduce this impact to acceptable limits wherever practicable. I There would be no long term effect on the acoustic environment. I 5.3 Air Quality The proposed work would not be a source of measurable air pollution. Exhaust fumes from dredging plant would quickly disperse and I would only be present during equipment operation. The requirements of the State Pollution Control Commission I would be met at all times. It is not expected that there would be any long term effects on the air quality of the surrounding environment as a I result of this proposal. I I F I - 15 - 5.4 Water Quality I There are two main aspects of water quality, these items being turbidity and salinity. Both types are affected by the I interchange of ocean and estuarine waters during the tidal cycle and by the level of urban stormwater runoff into Port Hacking. By not I undertaking this dredging operation, shoaling in the long term would impede tidal flows and so reduce tidal flushing. The salinity of the upper estuary would drop and increased turbidity would be prolonged I especially after urban runoff. The channel dredging operations should not adversely I affect Port turbidity because the spoil material is generally clean sand with only very small quantities of organic or clay particles. However, some localised turbidity may be created at Bundeena Wharf due to the presence of silt and mud in the estuary bed. It should be noted that the quantity being dredged at the wharf is relatively small and any temporary loss of water quality is considered acceptable in order to maintain the important community service provided by the ferry. I With the exception of Bundeena Wharf, water quality of the 'Port is not expected to be affected by the proposal. As outlined in Section 5.1 , the manner of spoil discharge would be controlled at the disposal areas and, at a dredging site, it should be emphasised that the I presence of sand and shell in suspension is a natural feature of flow within some of the navigation channels under strong tidal movement. Control would be maintained to ensure no spillage of oil 1 or other obnoxious or toxic substances from dredging plant occur within the Port. No rubbish or sewage would be allowed to be dumped from the I dredge and refuse would be c.ontained and disposed of in accordance with the relevant authority's requirements. I 5.5 Marine Flora and Fauna Although Port Hacking is undoubtedly a source of great I enjoyment to many amateur fishermen, there is no commercial fishing, prawn or oyster industry based on the waterway west of Hungry Point on the Cronulla Peninsula. This situation has resulted due to the I F I I I - 16 - relatively low coverage of marine plant life and the virtual sterility I of large areas of the Port. The mobile sand beds of the marine delta and the silty bottom of the mud basin between the marine delta and the I fluvial delta has made few contributions to the overall estuarine ecosystem. One important component of the marine environment in Port I Hacking is the rocky foreshore, particularly the "Shiprock" Aquatic Reserve at Little Turriell Point. It was the first aquatic reserve I declared in this State in 1982 and was established to preserve the site's recreational, educational and scientific value. The submerged I cliffs and pinnacles of weathered sandstone extend to a depth of twenty metres and are covered by a unique and diverse growth of marine I invertebrates and inhabited by a large variety of fish including some exotic tropical species. This Reserve extends for some two hundred metres along the I shoreline and projects sixty metres seaward. Dredging and sand disposal adjacent to this area would not infringe the minimum one hundred metre I buffer zone from the Reserve as requested by the Department of Agriculture - Division of Fisheries. Estuarine Protected Areas within I South West Arm and the Cabbage Tree Basin would also not be affected by this proposal, however, some works would occur adjoining the Carruthers Bay Artificial Reef as shown in Figure 1. It is not expected that this feature would be adversely affected by the proposal. Amongst the major elements of the limited aquatic I environment of Port Hacking are the habitats characterised by seagrasses, mangroves and saltmarshes. The latter two types are not I affected by the dredging operation. However, some seagrass of the Zostera capricorni species would be removed by dredging in the channels I located within Cunnamatta Bay and in the vicinity of South West Arm adjacent to Gogerlys Point. Both of these locations are within major I navigation channels for the waterway and are delineated by existing navigation markers. Since the contract dredged channel depth is approximately I 2.5 metres below ISLW, it is anticipated that the substrate would remain I I I I

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in a euphotic zone thus aiding seagrass recolonisation and a subsequent reduction in turbidity. With the exception of the two abovementioned areas, a minimum thirty metre buffer zone would be provided between the remaining beds and any proposed area of work. No defined beds of the more scarce seagrass species, Posidonia , would be affected by the proposal. I The impact of this proposal on the faunal and floral communities of Port Hacking is therefore expected to be minimal. The I Department of Agriculture (Division of Fisheries) has been consulted regarding the removal of seagrass at Gunnamatta Bay and Gogerlys Point and has not raised objection to this short term disruption to the Zostera capricorni community. 5.6 Tidal Hydraulics In the short term, maintenance dredging of Port Hacking of the scale envisaged would be no different to the present situation with no significant change to the existing tidal flows and levels or to wave action. In the long term, if no further maintenance is carried out or I an alternate solution found, channels across Burraneer Bay and at Burraneer Point would become unnavigable and subject to sudden closure I during severe storms. Conversely, continual maintenance of the navigation channels could gradually cause the middle ground shoal to contract and I ultimately disappear. Water depths on the seaward face of the marine estuary would continue to increase slowly due to the westward movement I of sand under the influence of the dominant flood tidal flow and continual maintenance dredging. I Burraneer Bay shoal would continue to build up and dredging would subsequently be required more frequently in the Burraneer Point channel as a result of this sand movement. 5.7 Public Amenity The dredge would partially obstruct the navigation channel in which is was operating. However, plant would be arranged in such a manner that there would be a clear passage for floating craft at all I I

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I times during the project. Where the discharge pipeline crosses an existing channel hindering traffic movement, it would be laid along the seabed, securely weighed down with all joints and seals watertight. The pipeline would be adequately marked and at a depth not to interfere with navigation. In other sections, the watertight discharge line would be I supported and suitably marked on the surface of the water by means of a system of floats. I To ensure minimal disruption to water based recreational activities, the dredging plant would be removed from areas of high water I traffic at weekends when peak use of the waterway is expected. Experience in previous dredging operations at Burraneer Point has demonstrated that dredging would cause minimal disruption to I public amenity during the contract period. Some disruption was experienced in launching the dredging plant at a suitable boat ramp, I however, this situation can be minimised by closing the ramp to the public at a time of low usage after prior notification has been [I publicised to the community. The proposal will not have any long term effect on public Li amenity and, in the short term, would improve navigational access of the Port until a more permanent long term solution can be enacted. 6. CONSIDERATION IN ACCORDANCE WITH CLAUSE 56 I OF THE ENVIRONMEW1AL PLANNING AND SSESSMENT REGULATION I "'or the purpose of Part V of the Environmental Planning and Assessment Act, the factors to be taken into account when I consideration is being given to the likely impact of an activity on the environment include that the activity may cause....." I (a) "Any Environmental Impact on the Communityt' It is expected that the surrounding residential community along the foreshores of Port Hacking would register only minor I incremental impacts from the proposal and that the community would not be adversely affected by dredging and disposal activities. The dredging I plant would be a localised short term visual impact on the surrounding I environment and generated noise is expected to be maintained within I I I

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acceptable limits and within the requirements of the State Pollution Control Commission. I The proposal is not anticipated to unduly disrupt waterway navigation. Moreover, maintenance dredging would improve boating safety and provide better access for pleasure craft. (b) "A Transformation of a Locality" The proposed dredging operation would not transform a I locality. Existing navigation channels would only be dredged and, on completion of the project, all equipment would be removed from the I estuary. It should be noted that Port Hacking has been dredged since the turn of this century and is a periodic feature of the Port. "Any Environmental Impact on the Ecosystems of the Locality" Port Hacking has a very low coverage of marine plant life I when compared with other major along the New South Wales coastline with large sections of the Port virtually sterile. The I communities of mangroves and saltinarshes within the river valley would remain untouched by this proposal as would the majority of seagrasses, I especially Posidonia Australia. Some isolated sections of Zostera Capricorni living within the existing navigation channels would be I removed by dredging, however, the contract dredged channel depth would allow recolonisation of these areas in the long term. It is considered the impact on the marine life within the estuary would be minimal. A minimum one hundred metre buffer zone would be maintained around the important "Shiprock" Aquatic Reserve and at least I thirty metres around defined bodies of seagrass communities, with the .exception of those previously mentioned isolated sections. I It is considered that the proposed work would not have a significant effect upon the ecosystems of the locality. Further, the I requirements imposed under the Fish and Oyster Farm Act would be met in carrying out this proposal. "A Diminution of the Aesthetic, Recreational, Scientific or Other Environmental Quality or Value of a Locality" The proposal would improve navigation along this waterway

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I providing better access for pleasure craft. Some minor disruption to boating within a channel undergoing dredging may occur, however, this inconvenience would be removed on completion of work. "Shiprock" I Aquatic Reserve, established to preserve this site's recreational, educational and scientific value would not be affected by this I activity. See also Section 5.5 - "Marine Flora and Fauna". "Any Effect upon a Locality, Place or Building Raving Aesthetic, I Anthropological, Archaelogical, Architectural, Cultural, Historical, Scientific or Social Significance or Other Special I Value for Present or Future Generations" There are no known localities, places or buildings possessing any of the above qualities which would be affected by this I proposal. As mentioned in Section 6(d) the "Shiprock" Aquatic Reserve would not be affected by this activity. See also Section 5.5 - "Marine I Flora and Fauna". "Any Endangering of any Species of Fauna or Flora" I There are no known endangered species of fauna or flora within the estuary which would be affected by this dredging operation. I "Any Long Term Effects on the Environment" This "once-off" maintenance dredging of Port Hacking is a relatively short term proposal. (See Section 3.2.4 - "Maintenance I Dredging of the Navigation Channels".) This proposal would immediately remove the risk of vessels running aground on sand shoals providing I "lead-time" for Sutherland Shire Council to investigate longer term solutions to this siltation problem. I "Any Degradation of the Quality of the Environment" The environmental impact of the proposed dredging I operation is expected to be minimal. The dredge and disposal pipelines would only incrementally impact on the visual amenity of the Port and would be localised to a particular area being dredged. Once the I dredging plant is removed, the area would not have been significantly altered visually from its original appearance. I It is not expected that the proposed dredging of Port Hacking would cause significant degradation of the quality of the I environment. I I I 1 -21- (i) "Any Risk to the Safety of the Environment" I Temporary channel markers and navigation signals would be used to direct traffic flow around dredging plant to the satisfaction of the Maritime Services Board and approval would also be sought from this body for mooring arrangements. In addition, where the discharge pipeline crosses navigational channels it would be submerged to a depth I sufficient not to interfere with boating movement. In other areas, the watertight discharge line would be supported and adequately marked on I the surface of the water by means of a system of floats. Dredging would also be limited to weekdays, a time of I minimum waterw ay usage. It is not considered that the proposal would add measureable risk to the safety of the environment. I (j) "Any Curtailment of the Range of Beneficial Uses of the Environment" On completion of dredging, safer navigation along this I waterway would be provided for boating and better access for pleasure craft. The risk of vessels running aground on sand shoals would be I removed as well as the even more serious problem arising from vessels running aground and blocking the way for other craft. I The proposed work is not expected to produce any curtailment of the range of beneficial uses of the environment. On the I contrary, the proposal would assist in meeting the increasing recreational demands being placed on Port Hacking. (k) "Any Pollution of the Environment" I It is not considered the proposed dredging would be a measurable source of pollution to the environment. Noise during the I construction period is expected to be within the guidelines of the State Pollution Control Commission and lasting for only short periods of I time. See Section 5.2 - "Acoustic Environment". The requirements of the Commission would also be met I regarding air pollution. Exhaust fumes from dredging plant would be subject to this authority's control. I F I I I

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I Water quality would be maintained as outlined in Section 5.1 - "Visual Amenity" and it is anticipated that the level of turbidity I would be confined to acceptable limits. (See also Section 5.4 "Water Quality".) (1) "Any Environmental Problems Associated with the Disposal of L Waste" During the dredging period, control would be maintained to I ensure no spillage of oil or other obnoxious or toxic substance from dredging plant would occur within the Port. No rubbish or sewage would I be allowed to be dumped from the dredge and refuse would be disposed of in accordance with the relevant authority's requirements. I "Any Increased Demands on Resources, Natural or Otherwise, Which are, or are Likely to Become, in Short Supply" Resources to be used in the proposed work are in I reasonable supply. The activity would not cause any undesirable shortage of fuels or oils arising from machine or plant operation. I Once a channel is dredged it becomes a passive element within the estuary, neither using raw materials nor producing I effluent. The relocated sand could subsequently be used in a future n commercial sand extraction operation as outlined in Section 3.2.2 and in accordance with the Sydney Regional Environmental Plan No. 9 - "Extractive Industries". (See also Section 3.3.3.) "Any Cumulative Environmental Effect With Other Existing or Likely ri Future Activities" The proposed dredging of Port Hacking is not expected to I result in any cumulative environmental effect. The proposed work would provide suitable navigation access for boating in the short term and I channels would more likely resort to their present arrangement in the longer term if no further management option is adopted. I 7. CONCLUSION It is considered that the proposed dredging of the navigation channels in Port Hacking from the Cronulla Peninsula to I Gogerlys Point and into Gunnamatta and Burraneer Bays is not likely to I significantly affect the environment. I I I

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I 8. REFERENCES "Draft Port Hacking Management Plan" - Port Hacking I Planning and Advisory Committee. March, 1988. "Fisheries Resources and Management Guidelines for the Port Hacking Estuary" - Fisheries Research Institute. I April, 1988. "Port Hacking Maintenance Dredging. Review of I Environmental Factors" - Public Works Department of N.S.W. April, 1986. I "Port Hacking Marine Delta Management Options" - Public Works Department of N.S.W. 1985, I "Review of Environmental Factors For the Proposed Dredging at Lilli Pilli and Burraneer Point in Port Hacking" - I Public Works Department of N.S.W. April, 1979 I I I I I I I I I I I I I LEcENc I' JF'ioPo3e' cINci I Pg0pc5Ep t713o L

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