THE BEACH PROTECTION AUTHORITY OF QUEENSLAND
REPORT AND RECOMMENDATIONS ARISING FROM EXAMINATION OF REPORT R 257 - 1970
BY
DELFT HYDRAULICS LABORATORY, NETHERLANDS
ENTlilED
GOLD COAST I QUEENSLAND I AUSTRALIA COASTAL EROSION AND RELATED PROBLEMS
Photo: GOLD COAST JUNE 1967 / I . --,:...." lUP9B·:r~.DM':-;'.l:(W::l!'! 1'1lO.T.ECTIO:il.:.-AI)i.LUc.u,y_ 50, .iU) ON DELFT REPffiT R257-1S70 ----..
A summary of the Repor t and recommendations entitled "The Delft Report on Coastal Engineering Problems on the Gold Coast - An Introd\lction" has been prepared by officers of Harbours and Marine Dep"rt::.ent for the Authori ty and accompanies this repor t. (Appendix A)
The Board has reviewed the rocommenda tions o:f the I:el:ft Hydraulics Laboratory Repor t and t!1e estimated costs :for their implementation prepared by officers of Harbours and Marine I:epartment :for the Authori ty.
The work proposed in the Delft Reper t can be regarded as falling into two categories, one :fundamentally concerned with structures at the mouths o:f streams, and the other wi th restoration and preservation of the beaches, although these are inter-related. Chart 1 attached indicates the priori ties and order of vKlrks in general terms.
Proposals :for the stabilisation i~ ~osioion and depth o:f the entrances of Nerang River and Currc::.bl.. Creek can be regarded primarily as co~sta1 engineerir.~ projects which have an influence on the stabilisation of the beaches, whereas the rehabili tation and preserva tion o:f the beaches proper is considered to require direct nourishment with sand.
It woUld seem that the two categories of work, :from their general nature, would have to be finar.c ed from'different sources. That o:f the first mentioned CQuld reasonably be regarded as mainly a government responsibility, and o:f the second, a C-02:J. Coast Ci~y ) Council responsibili ty. l The Board cons~ders the Delft Repor~ to be realistic and the recommendations sound. It recognises that the works progrrunme pro posed will involve a high early capital cost and that its financing will be difficult, -but it also considers that postponement 0;: action would involve gambling wi th the future of the Gold Coast beaches, the unknown factor being the weather and sea oonditions which will be experienced in the near future. There are insufficisut his torical data available to establish statistic&l values which would enable an accUl:'ate and quantitative, evaluation cf the risks involved were a programme embodying a lesser rate of early capital expenditure embarked upon. The following quotation from the report is considered to particularly apposit~: " If the cos t of these works makes it impos sible to oarry out such large scale beach imprcvements in a short time, part of the works at least musy be done immediately although, at' COUl'aO, in that case the direct increase of' sat'e ty wi 11 be proportior.ately Jess." The programme of work proposed in the Delft Report is shown in Chart 3 attached, on which estimated costs of the work are also recorded. The major works have been PtQgrammed to be carried out over the first ten (10) years, but continued pumping to overcome long-term erosion ef'fects and for entrance by-passing, and maintenance of strUctures and dunes will be essen tial. Expenditure would be nearly $M20 in the ten year period, rial,ng to about ~M28 in a twenty year period. Of this amo~~t, restoration and msintennnee of the beaches by sand nourishment and dune stabilisation are eXj;e eted to amount to CM13.5 in the first five (5) years, *!.!15.4 in ten (10) years and $M19.6 in twenty (20) years if work essential for the restoration and maintenance of the beaches only is oarried out, but slightly le ss if both eategories are implemented. The Boa.rd ,,10hes to point Qut that -3- the boulder wall system, while giving a measure of pl>O tection to pl'vper lIy, cot1.lil nevPY" be regarded as capable of protecting the beaches in a form attractive to tourists in the event of adverse weather conditions, the rev~rse in fact being the case. The Laboratory says: " AI. though the boulder walls proved useful for temporary protection, it is not probable that they would wi thstand the Wave attack during a period of heavy cyclones. The walls do not serve for beach improvement; they even have a negative effect on the natural restoration of the beaches in front of them, due to increased turbulence as a result of the reflection of the waves against the relatively steep slopes of the walls. Eventually the walls mus t be cm ered by sand, especially because they lYere buil t on the very beaches . where severe erosion occurred in the past and may occur again. II It. l:'IoCnybS t'l1e rxrlr~".-,;:tWl.·Y·s cont.r:>ntiOJl g,!.'n):r;. in the folIowing quotation that there is no reasonable a) t.:a>native to beach nourishment, and that wi thout it, heavy damage will be encountered at some time in the future, and this could be any year, and with no prelimin ary warning. The Laboratory says: " Because of the touristic use of the beaches, s~up-o··IJi' gl'oynes at small distances will not be acceptable. Besides, such const~uctione do not influence the transverse tl>ansport, so that in this case still 0 the I' action is necessary. With a limited number of structures it takes a long time before there is sufficient accret1Gn at some distance from that Ht.ructure,.... To accelerate the increase of the ],,':£.cll width l'\G some distance from a structure, a se·",,,d one can be bull t south of the first one after some time. Obviously, much time is involved in this process, which means that no immed:.&to protection is obtained • • ~ .. o ... oo ••••••• o· •••••••••• o ...... Taking into account all these considerations, it will be clear that the most direct and 0 afest way of protection is direct placement of sand in the areas where sand is needed, Vlhi ch means almos t evenly spread along the coast." -4- RECOMMENDATIONS As the minimum requireaent for early action the Board recommends as folio VIS :- 1. THAT THB' DELFT REPORT AND THE ACTIONS RECOMiJENDBD THEREIN BB ADOPTED BY THE AUTHORITY AND THAT TOO -REPORT 21TH THIS RECOllYBl;'UU.TION BE TRANSMITTBD-TO THE_GCVERNMENT. ALSQ, THAT THE RECOMMENDATION INCWDE THAT THE REPCR T BE REIEASED. 2. That immedi ate effort be made by the Authori ty. to S;O" that an ini ti al programme of IV:> rk be approved and implemented wi th a minimum of delay. These wor-ks would include the following in the category of direot beach protection: (i) The nourishment of Greenmount and adjacent beaches as recommended in the RepOl:' t and at an estimated cost of ~],j1.1 over 20 years (present day prices) - in this context, that negotiations be opened at top level for discussions with the appropriate Hew Soutl:.. Ylales authori ties to explore the means of obtaining sand for the purpose from over t~3 Border. (li) The primary nourishment of the beaches from Burleigh to the Nereng Iliver mouth wi th sufficient quanti ties to combat the long-term erosion effects until the full programme (arising out or the study ment!oned below) can be implemented, together wi th the recommended pl''Ie-reqnisj te of' construction of the inshore (groyne) i, [,l'ucture ,,"t, the northern end of the Spi'" This wor-1: :.8 "'.ltimated to cost ~)M1.5 (prel3':.j~·!~ day prices) :)\TG~" ti.·i"ee years. A study bfJ immediately ins'!;i t,uted to ascertain the feE.sible level of: expendi ture on major nourishment restoration of these beaches and a recommended programme resulting therefrom. 3. That in ~he category of: ro astal works appropriate action be taken to initiate works as recommended for the Herang River Mouth, the first steps being to arrange as a matter of: urgency :for a model study -5- to be made by the state Government, with Delft Hydraulics Laboratory as consultants, and for working plans to be prepared. 4. That the Department of Harbours and Marine be requested to arl'tL'1ge for the incorporation in future testing of Currw.bin Creek entrance model at the University of Queensland of those recommendations made on that problem in the Delft Report with a view to determining the detailed layout of the re quir ed training walls. In thi s con tex t, that the Universi ty be advised that the Delft Report is confidential until such time as Recommendation 1 above relating to release of the Repor t is realised. To view charts refer to original document. Could not be scanned as the file is size Ai APp]C,mIX A The Delft Report on Coastal Engineering Problems on The Gold Coast - An Introduction 1 • In 1964, the Co-ordinator-General's Department commissioned the Delft Hydraulics Laborat ory, Netherlands, to examine the erosion problems of the beaches of the Ci ty of Gold Coa st and to recommend a programme of investigations. Following the receipt of their report: "Queensland Coa etal Erosion Recommendations for a Comprehensive Coastal Inve s tig a tion" in 1965, extensive investigations were carried out by the Co-ordinator-General's Department along the lines suggested by the Laboratory. During the investigation l?"riod, close contact was maintained between officElrs of the Department and of the J,oh~",,,'''',,,,,. ? In April, 1968, the Co-ordinator-General'p Department formally requested the Delft Hydraulics Laboratory to assist in the evaluation of the data collected ald to recommend solutions to certain engineering problems of the City of Gold Coast. The Laboratory agreed to the request in October, 1968. Their findings were presented in 1970 in a report enti-tled: "Gold Coast, Queensland, Australia. Coastal Erosion and Related Problems". This reper t Vias prepared in two volwnes: Volume I - Conclusions and Recommendations Volume II - Investigations - Part 1 Text and Tabl6c Part 2 Figures. 3. Vol ume II contains a comprehensive summary, not only of the data colle cted by the Co ordinator-General's Department in their investigation, but also information such as historical backgrou.'ld, physiography and geomorphology etc. obtained from other sources. Volume II is the basis for the conclus- -2- Following the eoming into force cf the Beach Protection Act of 1968, responsibility for investigation of and recommending solutions to beach erosion problems was assumed by the Eeach Protection Authori ty, and the Co-ordinator-Genera1' s Depal'tment contInued to provide engineering services to that Authori ty. 4. The coastal engineering problems on which the Laboratory WaS requested to advise wel'e: (a) The beach erosion. problem in general; (b) The beach erosion problem in particular areas; (c) The effect of the Tweed River training walls on the Gold Coast beach regime and the over'-coming of any detrimental aspects of their effect; (d) The stabilisation in position and depth of the Herang River entrance; (e) The stabilisation of the entrance to Currumbin Creek, combined with the deepening of the Creek and development of a small craft marina; (f) The stabilisation of The Spit, southport, with a view to utilising the area for recreational purpos es. 5. The Laboratory considered the Gold Coast as three semi-related sections, i.e. Pt. Danger to Tugun, Currumbin to Tallebudgera, and Burleigh Heaolsnil +0 'Php Rvi t. Each of the above six topics are dis cussed separately and in detail. However the prob- 1ems, and any works which may be carried out on beaches wi thin each of the three sections, sre inter related, and. the programme of VI) rks recommended talces full cognisance of this fact. If some of the recommended works are ~leted for any reason, sufficient background has been provided for local Engineers to determine a revised programme. 6. The basic solution of the erosion problems given in this Report is a scheme of exten sive sand nourishment combined wi th structlires at Currumbin Creek Entrance and Nerang River Entrance. Because of the touristic use of beaches, groups of groynes at small distances are not acceptable. Besides, such structures do not influence the -3- transverse transport of sand, So that in this case, still other action woUld be necessary. The method of restoration adopted will ensure the preservation of the Gold Coast's beauty and surf conditions for tourist use. The recommendations of Volume I can be summarised as: ( i) lni ti al pumping of 11 million cubi c yards of sand to re s tore all beaches to a level at which they shoUld be maintained, wi. th con struction of groyne structures at The Spit and Currumbin. The quanti ties given in the report are based on a maximisation of sand losses taking the 1967 Cyclone season as the design season. Quantities to be pumped are such that the present "normal" conditions would be the designed minimum conditions after a storm season equivalent to that of 1967. The source of the major portion of this sand will be the Broadwater. A further consider able amount shoUld acme from either the Tweed River, Letitia Spit, or offshore from the Greenmount-Coolengatta area, the Tweed River source being the most desirable of these alternatives. Other sources will be Currumbin Creek and Tallebudgera Creek. Part of this sand nourishment must be used to reform dunes. (ii) In addition to restorati~e pumping, continu ing pumping of 500,000 CUbic yards each year to offset the long term erosion trend is required, sources being the same &8 describeu in (i) Maintenance work to dune areaS by fencing r...'ld vegetation is also necessary. (iii) Construction of training walls for the Nerang River Entr!tlce will provide stabilisation of the entrance in position and depth. (iv) Construction of training walls for the Currumbin Creek Entrance will make it accept able for the propos ed small boa t marina. -4- Note: In both l!"~ts (iii) and (iv), the eo>nstructic:a of' training wallo mug+, qlR.P Qnt,Cl:ll cnna b;ir passing systems to ensure the stability of beaches to the north of the entrances and to maintain entrance channel depths. It is a question of economy and policy whether some erosion of South Stradbroke Island is accepted. Serious erosion will weaken the co astal pro tection han ever. (v) It is advised that certain surveys are con tinued in order to determine the accuracy of the predic ted effec ts, ano. to revise predio'"')G, sand quantities. ATTAPlIMENTS TO: REPORT BY BEACH PROTECTION ADVlffiR Y BOA P.D - OF DELFT REPORT R257-1970 The attachments are abridged versions of repar ts prepared for the Board, and which aided it in its deliberations. The ab ridging has been carried out wi th a view to making ret'erences etc. cont'orm to the Board's Report. Attachment 1. Comments on the Implementation of Recommendations contained in Delft Report R257-1970. Attachment 2. Listings of Costs of Individual Projects. Attachment 2' Benefi ts accruing from Beach Nourishment and Entrance Stabilization. ATTACHMENT 1 1 .0 Introduction 2.0 Sequence o,f Works 3.0 Priori ty of Works 4.0 Beach Replenishment and Dune Stabilisation 5.0 Construction at River Entrances 6.0 Sources of Sand 7.0 Additional Works 8.0 Limitations of These Comments 1.0 Introduction Volumes of sand required for ini tial bea"" replenishment, and for the offsetting of long term erosion have been calculated. Apprcximate break water configurations, material quanti ties and associ ated sand by-passing quanti ties for the Nerang River and Currumbin Creek Entrances ha¥e been calcula ted. Order of vo rles, priori ty of wo rks and a time-table of works is suggested. Estimated approximate costs of works, usjng Dresent daY prices, have been calculated. The calculations, estimates etc. are based on the premi se that all recommendations in the Report are carried out in full. These notes are the basis of Charts 1 and 3 in the Board's Report, eng SC~87 _ . ::.'. included in this attachment. 2.0 Sequence of Works (Reference Volume I Section 3.6) A simplified sequence of works is shown on Chart 1 and the detailed sequence of works on Chart 3. 2.1 Phase 1 On Oh.ar--(. :> :L t. OWl be seen that while work takes place on construction or Boct-to.n oj of the south wall at Nerang, simultaneously the final shape of the entrance works will be determined from a model study. Also sand sources at the Broadwater, Tallebudgera, Currumbin and Tweed River N.S.VI. can be located and secured. 2.2 Phase 2 Replenishment of beaches and dunes commences at the Spit and p)"Ogresses southward to Burleigh Heao p , ~. th~ same time replenish ment of Greenmount Beach will commence. These two sections are the only two where large scale dredging equipment will be necessary. It can be arranged that all other "first off" and oontinuing pumpings will be able to be handled wi th medi um sized equipment wi th pump rates of about 2 million yds ./year. Construction of the Currumbin Creek Entrance and associated replenishment of Pa).:J, Beach and Currumbin Beaches is commenced. 2.3 Phase 3 Constructioti of the Nerang River Entrance is comple ted. 2.4 Phase 4 Construction of Currumbin Creek training walls is comple ted. It is not desi.l"'ab2.e (f'ro~ 00(,,1"1 engineer ing and financial as];8 cts) to build the breakwaters at the maximum pes sible rate of construction. It has been programmed that ooncbnwtion ot: the Nerang and Currumbin Entrance Works will be spread over several years, and with the Currumbin Creek North breakwater being constructed during a break in construction of the Nerang Entrance walls. 2.5 Phase 5 Replenishment of beaches from Coolangatta Creek to Tugun. As this section will not commence for some time there will be ample opportunity to evaluate the feasibility of resuming beach front properties at Tugun in preference to beach replenishnent. 2.6 Phase 6 As soon as any""" rks are completed, either entrance improvements or beach nourishment, pumping must continue. While this is included here as phase 6 it must be considered that the pumping must commence immediately after completion of the individual works e.g. at -3- the Nerang Entrance, supply o~ sand to South Stradbroke Island shou-1iI commence after con struction of Section 1 of the South wall. A close watch on the Ial and will be requi red to accurately determine commencement date or physical sand supply. 3.0 PrioritY of Works The priori ty of \\Q rks is no t 00 mple tel y detailed in Vol. 1 or the Report as the prioriti:3s for works will to some extent depend on existing beach condi tions at the time of s tart of works and on the funds available. The order of prior- i ties for works is not necessarily the same as the sequence of works. AS the sequence of "prks is governed mainly by the interaction of vari ous worl{s on one another the first priority work may not necessarily be the fir st section where work will commence. ~r:L~a--.:l.-t.j"""" .....- iI.o"''''.l''ihp.d. on r.h~rt 1. It should be noted that even if work on the Nerang River Entrance and Currumbin Creek Entrance is not carried out it will still be necessary to con struct sections of the south wall in both instances if beach replenishment is to be undertal 4.0 Beach Replenishment and Duns Stabilisation 4.1 Order of Pumping The general order of pumping to beaches is shown on Chart 1 and the de taile d pro gramme on Chart 3, which lists sources and quantities of sand. -4- Group 1 (see Chart 3) - After commencement 0:('. construction of Section 1 of Nerang River Entrance South Wall, pumping to the saddles on the dunes at The Spi t can commence. This is I"ollowed by pumping to be ache s from tile He rang Rive r to Narrow Neck. The quantity or sand required for this section is reduced by an allowance for the accretion in the sand fillet on the south side of the South Wall. On COffi- pIe tion of this section, pumping will continue southwards to South Nobby Headland. This total pump is for 10,740,000 cu. yds. and w:.:'.: require large dredges if it is to be completec in a short period of time. This discharge line. is a maximwn of 8 miles in length 8.01d thus it is considered that the reple nishment of Burleigh to South Nobby Headlend could best be done using Tallebudgera Creek as the sand source. This sand source is limited to relatively small quantities. (,,"UP 2 - Fbllowing the securing of a sand source (assumed to be the Tweed River) p'umping to Greenmount will commence. It is not considered necessary to pump to all beaches between Pt. Danger and Coolangatta Creek, only Greenmount Hill to Kirra Hill. As the amount of sand pwnped to this beach at anyone time should no~ be too great, three pumpings at 3 year intervals have been planned. It is expected that natural replenishment of Rainbow Bay and Kirra will occur from the sand pumped to Coolangatta Beach. This arrangement will allow regular surveys to be carried out to oheck the accuracy and necessi ty of replacing the 2.2 million cu. yls. withheld from these beaches by the Tweed Walls. The full 2.2 million cu. yds. will be 'placed on these beaches by year 17. Group 3 - After construction of the connecting wall anll wet,. Mction from the Mainland to Currumbin Rock, pumping to the Oe&~,00 -5~ between Plat Rock Greel> ,pncl Gurrumbin Creek, and Palm Beach can ~ommence. This involves pwuDing 1.79 million cu. yds. from Surrur,;bin Greek. The "",mal continuous pumping for Palm Beach has been reduced from 70,000 cu. yds./yea'r to 50,000 cu.. yds./year (Vol. 'I J)C1Yl""_ 3 .. 5 .. 5). TlJ.1S modification will l:av"e to be cont'irmed before the second maintenance pumping at year 11. GroUp 4- Replenishment cf beaches between Goolan~ gatta Greek and Fla t Rock Greek can be carriad out immediately prior to the 2nd pumping to Goolangatta Beach, thus utilising the same dredging equipment. A summary of initial and continuing sand quanti ties is shown in Table I. TABLE I Mnuf,l ~ Initial Rest~~ Continuous Fumuin.g Goolangatta Gk. 500,000 c,jil.yd. 50,000 eu.yd./yr. ~ Fla t IDe. Ok. (length 2.8 miles) Fl£I t Bl<. Gk. ~ 250,000 eu.yd. 24,000 eu.yd./yr. GUrrumbin Gk. (length 0.9 mile) Pl'lm Beach 800,000 cu.yd. 50,000 cu.yd./yr. ~length 2.5 miTes) Burleigh - 8th. 500,000 eu.yd. 32,000 eu.yd./yr. Nobby (length 1 mile). 8th. Nobby - 4,611,000 cu.yd. 194,000 cu.yd.!yr. Narrow Neck (leng;th 6 mile s ) Narrow Neck - 2,91 8,000 cu.yd. 123,000 cu.yd./yr. Nerang R. (length 3.8 miles) Greenmount 1,350,000 cu.yd. 8,900 eu.yd.!yr. Danger Point Ooolangatta Ok. (length 1.5 miles) TOTAL (Length 10,929,000 cu.yd. 481,900 cu.yd.!yr. 18.5 miles) -6- 4.2 Dredgipg Costs These are estimated at /.jOe/eu.yd. basic cost for discharge up to 6,000 ft., and \"Ii th an additional cost of 15c/cu.yd. for each additonal 5,000 ft. of discharge line and associated booster pump. The maximum cos t for s and is $1 .45/cu.yd. at NObby's Beach where seven boosters are required. It may be more economic to purchase a tract of land west of Nobby's Beach and pump from that source, leaving a lake connected to the proposed canal system in that area. It is likely that suitable sand oouJd be locatud in this inland area. The estimate of 40c/cu.yd. is based on a 24 hour pumping day. 4.3 Continuing Pumpi!l!; Vii th the exception of the ini tisl pumpings to the beac.l}es between Pt. Danger and Flat Rock Creek, all continuing pumping8 are bssed on a 10 year cycle. 4.4 Pumping Rates I t is mos t desirable that the time taken to supply sand to the beaches is kept to as short as pos sible. The maximum use of night Ill1IDDi ng. va 11 roi ni mi. f;A :i ru>ru\vG'oni.pnl1p. to '}:t;::. :=t.oh users. It is expected that localised dis colouration of the water will occur a t dis charge points. Thus it is rem lllJIlended that pumping rates in excess of 10 million cu.yds./ year be maintained for the initial pumpings for the Nerang River to South NobbY Headland beaches, and better than 2 million cu.yds/year for the other beach nourishment proj9 cts. Fbr the sand by-passing systems con tinuous dredging could be considered as it is expeoted that clean sood will be pumped and li ttle water disoolourstion will occur. 4.5 Dune Stabilisation On all beaches establishment of a dune to RL20.00 on State Datum by the initial pumping of sand is necessary. After allowing six months for salt oontent in the fill to reaoh an aoceptable level, fenCing, planting ~ I •• and fertilising of the dunes will be carried out. The fertilising will be spread over 18 months. No dune work is programmed for South Stradbroke Island. 5.0 Construction at River Entrances 5.1 Nerang River Entrance The first stage of the Nerang ~iver Entrance, Section 1 of the south wall, is approximately 10 chains long perpendicular to the bench and flr:ts .,pt!lmRl"t.l.y f\~ a gl~oyne. This secticn is estimated to cost t\250,000. DUring this construction, a model study must be done to determine the best layout for the remaining sections of the walls for the purpose of training the entrance. Two years after commencing construction of the groyne section model results, designs and tendering for the remainder of the wall should be compJe ted so that further con struotion may commence at the beginning of year 3. The model study will show the urgency for beginning the Nor th wall from Stradbroke Island. Designs and tendering for this W) rk should be compJe ted by the end of year 3. The cost of .the North and South walls is estimated to be 01,000,000 each. Erosion -8- prevention revetment work j.1)~d1e the ent:.'ance is estim,::l+Q>3. qt. ~ -£,t.'(.rti.h...:).~ $100,0000 Also, there is 0.5-1% probabili ty th"t maintenance costs or $60,000 will occur in anyone year. Cos t of sand by-passing using a dredge in the deposi tion area is estimated at 40c/yd. (b) If the offshore breakWater design is adoD+.e>d, total ('leo t i.e oot.imat;o-d -a. t. ~7,800,Cr,1) with 0.5-1% probability of ;{)225,000 mainten ance in anyone year. Cost of by-passing sand using a land based dredge is not available at this stage. 5.2 Currumbin Creek Entrance ' I~"~'(9" AIi I :..~~"Weir ~"Ltll-'f1 '''1 {<.~, fen /1 Ifj \~~-} fjl',' ""-. (""'~hl" '2>~,.".\y-<",,~.\-. .--c; / 1/ IF J ~)L ~. J----- I'M", ~ \ I-I ) ~(h I \ "" ----=---\- \ \ ~ \ "\' ~rl~Q~ At the beginning of year 2 (see Chart 3) work should ccmmence on the South wall complex. First to be constructed is the section between the mainland and Currumbin Rock. Other sec tions seaward of the Rock snd wi thin the entrance are to be completed by th~ end of year '. -9- Cnnq ... .-..,qtit'l)"l.. of thp North weJ.l 3hould cvmrocnoe at year 4.5 (SOQ Chart 3). Total cost of the entrance is estimated at $1,500,000 of which $250,000 for the weir section is of' primary priori ty for beach restoration works. There is 0.5-1% probability of ~)30,000 maintenance in anyone year. 5.3 Maintenance to Structures Fbr costing purposes an annual maintenar.ce expendi ture has been allowed. The total maintenance costs are estimated to be required in ally one yesu> with a probabili ty 0"£ 1J{. Fbr estimating purpos es an annual maintenance of' 1% of the total maintenance cost is allowed each year. It is probable that 10~ of' the maintenance costs could be required in any one year. 5.4 Timing of Construction It is impor tan t the t the fir s t stages 01' construction of the walls commence when specified as these act as integral phases of the beach restoration programme. Extension of the walls for river entrance stabilisation may occur slowly so that expenditure in any year is not excessive. 6.0 Sources of Sand (Exclusive of By-passing) From Chart 3 the total volumes of clean sand required from the various sources in the 20 years conside red are:- Broadwater 14,790,000 cu. yds. Currumbin Creek 2,030 ,000 cu. yds. Tallebudgera Creek 1,140,000 cu. yds. Tweed River N.S.W. 4,120,000 cu. yds. The first priori ty is to lcc ate sui table areas of the streams where this s and may be obtained l and to secure these areas as II reserved for future beach nourishment" • I t may be necessary to carry out a am all pilot dredging operation, or observe a dredging operation in the Tweed River, to determine approx- imate dredge bole int'i.ll .""tes bot'o"" the large cc~le be.Qch reSJ-tor>.ati.Dn. .pumrd·~a ...... o1Jlll}ences at Greenmoun t. The required volumes should be available from the various sources, provided it is reserved strictly for use on besch restoration works. After this ini tial 20 year peri od a total of about 480,000 yds. will be required each and every year for protection of beaches against long term erosion. i.e. Broadwater 317 ,000 yds/year Currumbin Creek 74,000 yds/year Tallebudgera Creek 32,000 yds/year Tweed River N.S.W. 59,000yds/year "7.0 Addi tiQnal Works On chart 3 the following additional costs are included:- (a) In the first two years: Further investigations, model work (Nerang Entrance) and proving of sand sources $100,000 (b). Surveys $ 50,000/year 8.0 Limi ta tioillL.9f..j;hes/LQQmmen ts 8.1 All sand quanti ties quot~ Ah"""<1 r~ '!"-'- &" reliable, being all based on figures quoted in Vol. 1 of R257-1970. The Charts 1 and 3 are compiled on the assumption that all works as recommended in the Repor t will be carried out. If some sand pumping, or breakwater construction is deleted, recalculation of sand quantities will be necessary. 8.2 QUanti ties for materials in the break- waters are approximate only, as exact wall dimensions and shape will not be determined until the model studies are comple te. 8.3 Estimated costs are calculated on 1970 prices. i.e. costs at' all works are the cos ts of works if the works were carried out today. No interest f'igures, inf'lation coef'f'icients etc. were considered. Cos ts of' breakwater construction were estimated by comparison wi th cons truction cos ts c£ Tweed Walls and Gold Ccast Boulder Walls. Detailed construc tion Ire thods f'or weir sections, of'f'shore breakwaters and transporting mnterials across the Broadwater have not been considered. 8.4 Estimated costs of' pumping sand are approx- imate only, as coo ts depend on many f'c.ctors other than discharge line length fu,d yardage, not the least being the dredges available i;, Australian waters at the time of' calling te;:de' and the .Commonweal th Gov ernment condi tiona on bringing in f'o~eign dredges. Plli~ping costs are on the assumption that the sources of' sand, as specif'ied in Section 6, are available. 8.5 No consideration of' pumping f'rom of'f'shore sources Vias given as with existing equipment, these pumping costs f'ar exceed costs of' conventional dredging. If' of'f'shore mining is commenced then it may be f'easible if' sand .c:rt.ill size is suitable, to purchase the silioa sand tailings f'rom this operation f'or placement on the beach. 8.6 The start of' Vlorks as year zero is taken as the datum f'or Chart 3. This year zero could be January 1, 1972. This would allow documentation of' Section 1 of' Nerang River South Wall to be comp1e ted. It would also allow slightly more than 18 months f'or model investigations. -----*"''',*----- , I ! , I I i ! ,• i ! I ! I ; , , ! , .. • I I ; j.:;:;;; ! , ! I : I i ; ! i /' L' ; , i ! ! I , I , I 1/ 0, , , I : , .",;" , , ! .... I i___ '~ ... ' . I 24 , I ",,' o· , / i I , I I I ! I 21 i' , Vl i L. , c ~ k': ~ i .... ' ; o 19 I "C i ! ._. . -. ,/ b 18 -r-- ' . ! Vl 17 / . -'. e 1/ i : .2~ " ~ , )/ : J. ! E 15 I I I I I ! I 14 / .;- L7 i Ul /' : l- ~- ·1 Ul V I 0 I I u ; 'i--- Ii v I I / ! 0 / 1 . Vi I • W 10 /! --I' ~ .- : , ~ 7' , I / • ~ I I V , l-- I Ul ! J ---- ... --'-_. --- , f- : W i I ! 71----1 / .. ; f- .. ! -- .-•• l----.. ,I i I 6 I ,i i .. ' -- .. 1- 5 I r 1--" . 1---. __ ~'r~ du:rin~ ye~r. 4 I J~ 3 2 ~ 1 I- 0 1 2 3 4 5 6 7 8 9 ,lE,~ ~~ ·"Jl'\-'\~n~lE.~ YEARS COSTS/YEAR CUMULATIVE COSTS II Initial Costs - Alternat ive A. Initial Costs - Alternative A. l\\ll "Total Costs - Alternotive 't{. ------"rotal Costs - Alternat ive X. NOTE:* Tatol ~ Initial + maintenance + further investigations etc. Appendix to report prepared by Beach Protection Advisory Board Of! Delft Report, R 257-1970 SC 887A ATTACHMENT 2 The following data sheets are included: I Sununary of Individual Pro j'! c t Cos ts. II Total Estimated Cos ts of - (a) Entrance Stabiil.sati01l only (b) Beach Stabilisation only Taken as two unrela ted projects.. III Estimated cos ts of Necessary Warks - Coolangatta- Pt. Danger. IV Estimated 00 st at' Groyne, Dune Works at Spi t and Limited Pumping to Beadles, Nerang River to Burleigh Heads. SUMMARY OF INDIVIDUAL PROJECT COSTS - TAKEN FROM CliJillT 3 1970 pm CES IN DOLLARS PROJECT IN! TIicL COS TS CONTINUING COSTS* SUB-TOTALS 1. Breakwaters (a) Nerang River Entrance (including reve tmen ts) 2,100,000 9,750 (b) Currumbin Creek Entrarce 1,500,000 $ 3,600,000 5,250. 15,000 3,615,000 $ 3615,000 * I 29 Sand By-passing Nerang -. 5,040,000 Currumbin - 1,920,000 $ 6,960,000 6,960,000 $10~75,000 3. Sand Pumping Nerang River - Narrow Neck 1,298,684 839,396 Narrow Neck - South Nobby Headland 4,945,000 4,171,000 South Nobby Headland - Burleigh Hoad!" 275,000 352,000 Palm Beach 46y"OOO 580,000 Currumbin Creek - Flat Rock Creek 100,000 192,000 Flat Rock Creelc - Coolan:;atta Creek 419,643 1,007,141 Coolangatta Creek - Pt. Danger 872,000 $ 8,374,327 96,000 $ 7,237,537 15,611,864 ~)26 ,15 ,864 .. - PROJECT INITIAL COSTS CONTINUING COSTS" SUB-TOTAL II I 4. Dttne Stabilisation I I Nerang River -Narrow Neck 60,000 . Narrow Neck - South Nobby Headland 96,000 South Nobby Headland - Burl~igh 16,000 Palm Beach 40,000 Currurnbin Creek - Fla t Rock Creek 14,400 Flat Rock Creek - Cool~~gatta Creek 44,800 Coolangatta Creek - Pt. Danger 24,000 ~) 296,QOO ) $ 277,500 573,500 $26,760,364 5. Miscellaneous l.\ode]Jl 100,000 - Surveys - 1,000,000 Speci al Dredging - 4~ 100,Oeo 15,000 $ 1,015,000 1,115,000 $27,875,364 I --: $12,370,:'1:7 $15,505,037 $27,875,364 ~~27 ,875,364 I , I - o· '. Continuing Costs: Include, continuing pumping, sand by-pass'ng, maintenance o:f works, and surveys. Xl TOTAL .lli2TI:.:A~~D_.QCS.TS..ill:' ( a) EN'TR/J.lCE STABILISATIQN IN DEPTH ],1':) r,xn~=:" (b) SEACH STABIU&l.ATION. . TAKEn AS TWO UNRELATED PROJECTS All estimated costs are at 1970 figures. Cos ts for each proje ct are estimated assuming the other project is not done. Cos t totals are calcula ted from est!. mates on Chart 3 and are totals for the 20 year period. Limitatio~s on accuracy of cost estimates are as for Chart 3 estimates. (a) Costs for Stabilisation of River Entrances On1U This excludes costs of works within the entrances such as construction of Marinas etc. Cos ts are listed: Nerang River Walls 2,000,000 .. The Spit - Stabilisation &: maintenance 275,000 Sand by-passing 5,040,000 Models and Investigations 70 ,000 Maintenance to Walls 9,750 Revetments 100,000 Spec:f.n1 n~o.;l5j.~'1gtl SUb-Total $ 7,504,750 CurrUlIlbin Creek Walls 1,500,000 Maintenance to Walls 5,250 Sand by-passing 2,160,000 Special Dredging 5,000 SUb-Total $ 3,670,250 Surveys at ~10,000/yr. 200,000 Sub-Total (y200,000 Total $1'l,375,OCO -2- (b) Baach Stabilisation The basic figures, and timetable and costs, are taken from Chart 3. Additional cos ts are also incurred in several instances, e.g. some by-passing of sand will be required at both Nerang and Currumbin, in addition to the beach nourishment. The by-passing will be for a limited period only. It is assumed that 600,000 yards will be by-passed at CUrrumbin, all in the first 5 years. It is assumed that 4,445,000 yards will be by-passed at Nerang, one half of this in the first 5 years and the remainder in the neAt 5 years. -3- ------~----~~~------~~----~-' ESTIMATED COST I~l $ (1970 PRICES) PROJIDJT In First In First In ]lirst : 5 Years 10 Years 20 Years Ini tial Cos ts Groynes (Currumbin & Nerang) 500,000 500,000 500,000 Reve tmen ts (Nerang) 50,000 50,000 50,000 Further Investigations 30,000 30,000 30,000 Dune Stabilisation 279,200 296,000 296 ,00°1 Sand Pumping - Nerang R. - Narrow Heck 1,298,684 1,298,684 1 ,298,6b!,: i I Narrow Neck - Sth. NobbY 4,945,000 4,945,000 4,945,000 - I Sth. Nobby - Burleigh 275,000 275,000 275,.)00 Palm Beach 464,000 464,000 464,000 Curro Ck. - Flat Rk. Ck. 100,000 100,000 100,COO Flat Rk~ Ck. - Coolangatta Ck. 419,643 419,643 419,643 Coolangatta Ck. - Pt. Danger 464,000 668,000 872,000 /-c------$ 8,825,527 \/ 9,046,327 ij 9,250,3:::; ; ~tont,j DUi..ng cos ts Maintenance of: Groynes - Nerang (incl. revetments) 500 1 , 5l"v-J I Currumbin 333 1,OCL Surveys 200,000 400,000 800,oeo Sand By-passing - Nerang 889,000 1,778,000 1 ,778,000 CUrrumbin 240,000 240,000 240,000 Dune Repai rs 92,500 277,500 Sand FUmping - Ne rang R. - NarroVi Neck 527,370 527,370 839,396 I, Narrow Neck - Sth. HobbY 2,085,500 2,085,500 4,171,000 Sth. Nobby - Burleigh Heads 176 ,000 176 ,000 352,00e I Palm Beach 290,000 290,000 580,000 Curro Ck. - FIa t _R!e. Ck. 96,000 96,000 192,000 Flat Rk. Ck. -, C'gatta Ck. 167,857 587,499 1,007,14-1 I Coolangatta Ck. - Pt. Danger 24,000 60,000 95,000! I Sub-Totel if 4,695,727 $ 6,333,702 i $10,335,5371 Total $13,521,254 $15,380,029 I$19,585~64! J .! lIT ESTIMATED COOT OF NECESSARY WORKS DURING 20 YEAJl!l: FOR_:eT ... DANG'RR " CC.0~I!i\fGATTlL...9.nE:&l). 1.0 These calculations are based on the fieures on Chart 3. 2.0 Initial Cos ts 2.1 Investigations (say 10% of total) for location and proving of sand sources $ 10,000 2.2 S.and Pumping $872,000 2.3 Dune Stabilisation $ 24,000 Total $906,000 3.0 Continuing.Costs Continuing costs are those expended during the 20 years considered on Chart 3 3.1 Sand Pumping. After pumping at year 7 continuous pumping will be on a 10 year cycle. i.e. the next pumping after year 17 would be at year 27 ~ 96,000 Dune Stabilisation MaintenaHce $ 13,500 3.3 Surveys (say 10% of $50,000 per year) $100,000 $209,500 20 year TOTAL $1,115,000 . ,;. E~TTIiATED EXPENDITURE IN $A < ••CA!!! 1970 PRICES) ExP..'!pci t tlll~'L. \>y ye aI's, for Pt. Danger to Coolangatta Cr~ Year Cos t/year . Cumula ti ve Cos t . 1 15,000 15,000 2 293,000 308,000 3 24,500 332,500 4 9,500 342,000 5 205,000 547,000 I I 6 5,900 552,900 7 5,900 558,800 8 245,900 804,700 9 5,900 810,600 10 5,900 816,500 11 5,900 822,400 12 5,900 828,300 . 13 ~,9DO 034,200 14 5,900 840,100 15 5,900 846,000 16 5,900 851,900 17 5,900 857,800 18 245,900 1,1 03,700 19 -5,900 1,109,600 20 5,900 1,115,500 f- TOTAL ~1 ,115,500 J1,115,500 I , ~ Note: All pumping is to Greenmount - Coolangatta Beach. ESTI].!!<.;rED COST~"r """.L,",". DUNE ';lOFKS AT THE SPIT MID LIMITED PUMPING TO BEACHES, i'TERANG RIVER TO BURLEIGH HEF~S Cost of Works for first three (3) years. No maintenance provision for any works is included. Dune stabilisation of the beaches, Nerang River to Burleigh Heads (with the exception of the Sp1 t) wi 11 not commence until after the large ini tial pumping 1s completed. 1 • Grolme Estimated cos t of the Groyne. No main tenElnCG -o<:c -to a.L'e 11l.V v.i. de 0. ~ 290,OGJ 2. Reve~ments Estimated cost of revetment works for the Spit is 050,000. These revetments are necessary to ensure stability of the Groyne. No allowance has been made for revetment works on South Stradbroke Island. $ 50,000 Filling of the Saddle s, The Spi t $ 200,000 4. Stabilisation of the Dunes, at the Spit only. No maintenance of dunes is required J.u bld.a po%'ind 40,000 Surveys and Investigations $25,000/year $ 75,000 6. Pumping to Beaches, Nerang River to Burleigh Heads to offset 3 years long term erosion (to maintain status quo) $ 900,000 Three Year TOTAL $1,515,000 ATTACHHENT 3 Quali tative Id~lL9;L.]mportance. of J.;r~d.amag~ i This last quotati. on Ls \)nQq~:l;i:...... -voet1. .;I.:u· -reJ,:-a-b:Lr'--€)_ +..f:lp economy of the area to the continuing ensured safety of the coastline. A telephone enquiry of Hr. A. Stenders of Clarke, Gazzard and Partners resulted in his informing the Vlri tel- that the firm had no detailed figtITGS \'Ihich could be used to quantify these statements. Damage Occasioned by 1967 blrents The darnage occasioned by the 1967 events are a reliable indication of the tangible benefit which \'Iould be conferred on the area \'Iere the nourishment proposals proceeded with. -2- The damage costs fall into tirreecategories (i) Damage to public property (ii) Damage to private property (iii) Loss of revenue to the community caused by the public reaction to the events rosultin~ in fewer tourists visiting the area in the post-June 1967 per·iod. (i) Immediate damage to public property during the severe storm of 27th/28th June 1967 lias estimated at SHO.6 (See: "Erosion of Gold Coast Beaches, 1967" by B.L. ~\cGrath Jour. I.E. Aust. July-August 1968). Damage (to actual development) in eat'lier storms that year was less. Thus a figure of $MO. 75 is adopted as the dar,lage to pul)lic property. (ii) No figures are available for damage to private property. However the proportion of the length of beach most serioccsly affected backed by private development is greater t~"'n the proportion backed b.1' public development. Thus an assumpti en of an equivalent amount of dana:<;e to (1) above seems justifiable. (iii) The Gold Coast City Council, throug.'1 ths jl]ayor and City Engineer, supplied their estiwates of gross loss of revenue to the local cownunity due to the events in question. Of course, one cannot say for sure that the falling off in tourist numbers after June 1967 ~/aS due solely to the erosion scare and bad press, but no other factors, apart from the western Que ens land drought, spring easily to mind as likely causes. The Council estimate, supplied by phone, is as follo\ls: Total value of tourlst trade to the area if e.ll accommodation fully utilized throughout whole year, Le. a 100% occupancy rate, b $H80 (for conditions immediately pre-1967). Occupancy rate in normal year is 80% - val,,? $1164. OC~upancy rate in year June 1967-June 1968 fell to 45% - value $M36. Thus loss in year subsequent to erosion compared to normal year is $M28. Assume that 701> Le. $1120, of this is attributable to erosion damage. -3- The figures of course are not too firmly based except the 45% occupancy value. Air traffic fi&;ures fell also in the year succeeding June 1967, but increased by 220 the next year, 37)1, the following and by last year \lere 72% of the 1967-68 year values . . Because of the growth rate of the area - populati on increase 8.81; compound and general development 10-15;_ per annum compound - cos'cs of a similar occurrence with similar public reacti on novl would be of the order of $/126. However a second repetition in the near future of the damage of 1967 might have a more serious and more lasting effect on public reaction by giving the Gold Coast a "reputation for erosion disasters" and shaking public investment and tourism confidence e.g. witness the effect of even the '\,;eather Bureau publicity re cyclones on tOl.;\:rism in the Barrier Reef Islands. Updating the costs of actual damage to public and private property to to-day's values, the repetition of 1967 events on the Gold Coast in 1971 could cause a loss of $1'128 to the community, beina $lIi? FI"+'l1,,,l (l~mp(to ..... ~a ¢J>!I:O.(: .f ..... r",~ .... ~~i~l .1A ...... u£ 'tUrnover. Even if the latter figure is "inflated", the loss will be considerable. Damage to Various Areas of the Coast Information to split the above amounts as applicable to various areas of the coast is not available. HOliever it is reasonable to assume, because of developmen":; patterns, that more than half the above $H28 would apply to the area north frOM Burleigh. Dama~e to Business in Coolangatta Region due to Loss of Greenmount and Kirra Beaches In response to a telephone request, the Yresident of Coolangatta Chamber of ComDlerce }.Jr. T. ilatt supplied the following information: "The writer has made a survey among a select~on of business proprietors in Coolangatta in e.n effort to determine the extent to which businesses have been affected by reason of the loss of beach at Coolangatta. It is most evident that the loss of the beach has had a serious effect on the takings of almost all bClslnesses in the town. Those busine.sses l;hich are nearest to the beach are the worst affected ru1d the effect seems to reduce on a sliding scale as the distance from the beach increases. -4- Certainly thQ loss in money w,"m'~ hI=> 0. ~,~8ry considerable sum, but th" Wrj tar f.p',,1 ~ no Ivould be ur.able to give any accurate figure. The proprietors estimate the loss of business Vlhich they attribute to the lack of beach to be "50% or more" for beach front kiosks, "at least 25,;" for beach front hotels and 25% for milk bars and the li){e in the main shopping area. All business oVlners intervieVled by the writer indicated that there had been a loss in takings. It seems more than reasonable to accept that the lack of the beach is the reason for these losses in income particularly when one con sid ers that GreenIilount Beach, for example, used to accoJllifrodate 3,000/4,000 people on a normal day in holidays or at week-ends, Vlhereas now there would be insufficient beach for 300/400. The whole economy of this tOl'iIl depends on tourists and most tourists come to the town with the idea of spending their time on the beach. It is obvious that so long as Ice have no beach our tourist numbex's Vlill be greatly reduced and the prosperity of the tovm adversely affected. Yours faithfully, COOLAHGATTA OHAN-"2R (\" <;Oi~P' :t;. (Sgd.) T.J. 'ilatt. 22nd January, 1971." Detailed figures are available for one Coolangatta business - the G.A. Robinson NSl-lSagency. Gross turnover has increased each year since 1947/48, except 1967/68. Fi~!res for the last fel'l years are: Financial Year % Increa,fH;L.c'U.9·'· l)c.d"ase (-) r p1:a ti ve .to preceding year 1963/64 +4.5 1964/65 +18.8 1965/66 +15.4 1966/67 +0.8 1967/68 1968/69 +4.2 1 Of-.".?J' fU +7.5 Sales of such a business arc related to "eathe::- as well as the number of tourists in the s.rea, but tuo facts are apparent, the drop-off in business in 1967/68 and the failure of growth rates in latter years to reach those rates of pre-1967, probably due to the lack of beach in the Greenrl0uLt-Xirra Area. -.5- Unimproved Value o~ Land. Oity or Gold Coast At the last major re-evaluation or land within the city, June 1965, the total unimproved real-property valuation was $M88+. In particular areas, val uations are as rollows: Mal.nBeach -$1.1 1.8 Surfers Paradise 27.0 Broadbeach 4.0 Mermaid Beach 4.5 North Burleigh 2.5 Burleigh 7.5 Palm Beach 3.5 Currurnbin 4.5 Bilinga 2.0 Coolangatta 10.0 Total $M67.3 being 7;1%± o~ the total Oi ty vaLuation (which includes Southpcr t WId the Islands Capri and Chevron). A A new valuation is in progress and is expected to be comp1e ted in June this year. Values overall are certain tc r'LL. A Senior 'Illaluer rrom Valuer-General t s Orfice inrormed the writer that, rcr example, Sur.Cers Paradise valuations would rise by about 50f'0, but areas such as. Palm Beach would rise by a lesser percentage. Assuming that, for the coastal areas listed above, valuations will increase by 20% on the average, the total present unimproved valuation or coastal areas listed is $1.180.8, of which $1.156.8 or 70% is north or Burleigh. Val ue or Improvemen ts No detailed estimate o~ the value or property on the Gold Coast is possible in the time available. However the Editorial or The Gold Coast BuHetin of' 21/1/71 S'lYS that buildings approvals ror the period 1961-70 totalled $M162. This being the case, it would seem l:'easonable to double this / rigure ror the total value or buiMings in the area = $11324. Assuming bui~dlngs values split in the same ratio as unimproved property values, the value or buildings in the coastal strip mentioned above 1s 324 x 7;1% '" #M243, or which I 70% us assumed to be north or Burleigh. -9- The amounts quoted above are in the nature of preliminary estimates only and require more detailed checkil'.g and analysis before being accepted as accurate. In ·elle present form they give an idea as to the order only.