• • • • Tarban Creek Seawall • • Report MHL670 • November 1993 • • • • • • • • • • • • • • • • • J • • • • • • • TARBAN CREEK SEA WALL • • • • • • • • • • • NSW Public Works • Manly Hydraulics Laboratory • • Report MHL67i), November 1~93 • PW::> ReI'ort No. 93091. ISBN 0 73JO 2730 2 • • • • • • • • • • • • Foreword
• The work descnhed m thIs report was carned out by Manly HydraulIcs Laboratory for NSW • PublIc Work:., MetropolItar.. Northwest Branch, actmg on behalf cf the NSW Health Department The work was CarrIed out and r~port prepared by R A Cook The assIstance of • officer~ ·;f Survey and Land InformatIOn ServIces who carned out the SIte survey a;',d staff of Coffey Partners InteInatlOnal Pty Ltd who carned out the geotechnIcal mvestIgatlOn IS greatly • apprecIated The efforts of officers of Coast and Estuan:!s Branch who carned a prelImmary • appraIsal of the eXlstmg seawall, adrrunIstered the mvestIgatlon on behalf of MetropolItan • Northwest Branch and contr~'.)uted suggestIons dunng the project IS also apprecIated • • • • • • • • • • • • • • • • • • • • • • MHL670 - 2 '.• • • • • Summary • The grounds of Giadesvilic tIospltal contain an area of recldlmed land with a frontage to • ! arban Creek The reclaImeJ land IS retaIned by an old seawall, 'lpproxIn~dtely 580m long, constructed from dry ~tacked sandstone blocks The f.eawall has de ten orated over time and IS • now In poor condition Attempts have been made to reparr some failed scdJons of the seawall • but these repairs t1ave not been successful The owner of the Site, the NSW Health Department, wlshe~ to restore the seawall to a satisfactory slate or to replace It With a sUitable • alternative as port of the redevelopment of the site • Site inspections to deterrrune the Cor.dltIOn of the eXisting seawall and investigations to provide deSign parameters for the reconstruction of the seawall or constructIO!l of a • replncemcnt structure were carned out DeSign parameters Included water levels, wave • COnditIOnS, a strIP survey along the wall (lnd a geotechnical InvestIgctIon • It was concluded th3t the present seawall IS collapsing because of eroSIOn of fill from directly behind the wall and that the seawall IS beyond economic repair A number of options for • replacement structures were evaluated and indicative cost estlmate~ prepared It was found • that the cost of constructing a sandstone seawall to repldce the present wall would be prohibitive due to the high cost of bUYing sandstone blocks to brIng the dimenSIOns of the • seaw'lll up to current rock wall practice
• The optIOn recommended as mo~t SUitable was a composIte scheme comprIsing 250m of • seawall In the area most exposed to wave attack, a sandy beach ari1roxlmately 50m long to replace the eastern end of the present seawall and lining the creek section of the bank With • nplap The: seawall would be of dry r0ck constrloctJon Similar to the f"esent seawlll and ut':lse the sandstone blocks reco"ered from the eXisting wall suppkmented 'JY cast concrete • blocks In the .ear of the sea,vall where they wou!d not be vl31ble to mcrease the thlckne~s of • the sedwall The e'>tImated cost of thls option IS $309,000 • • • • • • • • • • • MHL670 - 3 • • • • • • Table of Contents • • 1. Introduction 6 2. Investigations 7 • 2 1 Condition of EXistmg Seawall 2 2 Site Survey • 2 3 Geotechmcal In vestIgat,ons • 2 4 Water Levels 25 Wave Climate • 20 Currents • 2 7 Construcnon Constramts 3. Options for R~.storation or Replacement of Seawall 14 • 3 2 OptlOn 1 - Rock Seawall 3 3 Option 2 - GablOn Seawall • 3 4 OptlOn 3 - Cnb Wall • 3 5 OptlOn 4 - Stable Beach 3 6 OptlOn 5 - Riprap Armoured Slope • 3 7 OptlOn 6 - Reno Mattress Armoured Slope • 4. Preferred Option 19 • 5. Conclusions and Recommendations 22 • 6. References 23 • • • • • • • • • • • • • • MHL670·4 • • • • • • List of Tables • 2 1 Seawall InspectIOn 22 Still Water Levels for Sydlley Harbour • 23 DeSIgn Wave CondItions 2'~ Boat Wave Measurements • 31 Umt Costs • 4 1 indIcative Co~ts of Seawall OptIOns • 4 2 RIprap Rock Gradmg • List of Plates
• 1 EXIstmg Seawall- Chamage 81m and 190m • 2 EXIstmg Seawall - Chamage 286m • List of Figures
1 1 SIte LocalIty Plan • 2 1 Key to SIte InspectIOn And Plates • 2 2 Conceptual FaIlure Mecharllsm 3 1 OptIon 1 - TypIcal Rock Seawall • 3 2 OptIOn 2 - TYPICal GabIOn Seawall 3 3 OptIon 3 - TypIcal Cab Wall • 3 4 Option 4 - Stable BeaCh • 3 5 OptIon 5 - RIprap Sk'pe 3 6 Option 6 - Reno Mllttress Armoureri Slope • 4 1 Plan of Preferred OptlOl1 4 2 Preferred OptIOn - Beach Cross-SectIOn • 4 3 Preferred Uption - Rock Seawall • 44 Preferred OptlOn - RIprap Il1 Creek SectIOn • Appendices • A Survey P.esults • B Geotechmcal InvestigatlOn • • • • • • • MHL670 -5 • • • • • • 1. Introduction • Tarban Creek IS a tnbutary of the Parramatta River, Jommg the nver Just downstream of the • GladesvIlle Bndge It IS re!atIveiy narrow for much of ItS length before broademng out mto an estuary approxImately 100m wIde and 800m long A footbndge over the creek effectIvely • marks the transItIOn from the narrow creek sectIOn to the wIder estuary sectIOll The seawall • WhICh 's the subject of thIS report lIes along the ~outhem sIde of Tarbar. Creek wlthm the • grouilds of Oiadesville HospItal. The locatIOn of the seawall IS shown m FIgure 1 The seawall, constructed from a smgle row of dry stacked ~andstone blocks, IS approXImately • 580,n long over?ll WIth approxImately half of ItS length bordenng the wIder part of 1 arban Creek and naIf bordenng the narrower creek sectIOn The upper lIrmt of the seawall IS near to • the tidal lIrmt of the creek The maxImum normal tidal range along the wall sectIOn IS I 8m • The pnmary purpose of the seawall IS to retaIn fill WhIch has been placed 0n estuarme mudflats to form a level area presently used a& playmg fields The section of seawall • bordenng the creek also protects the bank from flood scour while the sectIOn bordenng the • estuarIne sectIon of Tarban Creek protects the bank from wave actIOn • The seawall has detenorated over time and IS now m poor condition The owner of the Site, the NSW Health Department, WIshes to restore the seawall to a satisfactory state or to • construct other SUItable protectIOn as part of ItS redevelopment of the Gladesville HospItal site FollOWIng restoratIOn of the bank the Health Department WIshes to transfer the care and • maIntenance of the foreshore area to Hunters HIll Mumclpal CouncIl
• ThIs study was undertaken to deterrrune whether It would be feaSIble to restore the seawall to • a <;atI~facto~y state and to InvestIgate cptlons for replacement of the wall All levels ~n thos • r.:port have been :educed t') a datl1fE 100 Q.1m below Austrailan Height D<1tum CAHD) • • • • • • • • • • • • MHL670-6 • • • • • • 2. Investigations
• 2.1 Condition of Existing Seawall • The condition of the eXlstmg seawall was assessed followmg a !>Ite mspectlOn carned out by Manly BydraulIcs Laboratory (MHL) and from a site mspectIon and geotechmcal • mvestIgatlOns carned out by Ccffey Partners InternatIOnal
• The eXlstmg seawall IS constructed from dry stacked blocks of Hawkesbury Sandstone with • sizes rangmg between 600 x 400 x 200 and 1300 x 500 x 400 The surface of the playmg fields behind the wall IS uneven but IS at approximately RL 10 1 5m The crest of the seawall • apoears to have ongmally been at about RL 101 5m b'lt due to the detcnoratloll of the wallis now generally lower It appears that the or: gmal height of the wall vaned between ab(mt 1 6m • and 2 3m • The overall length of the eXlstmg wall IS approximately 580m A plan view of the site • showmg cham ages along the seawall IS shuwn as Figure 2 1 ThiS figure provides a key to the chamages referred to m the site mspectlOn and to the location of photos Chamages along the • bank have been measureC: from the return m the seawall at ItS eastern end The 10m length of • the return should be added to the chamage to get the overall wall length • A total of about 440m of the wall has collapsed or partially collapsed With matenal eroded away from behmd the wall for distances of up to 3m The concave (m plan) section of the • seawall from Chamage 0 to 140m appears to have sustamed less damage then the convex • seCllon between Chamage 140m and 270m, probably due to the- honzontal archmg actIOn of • the wall m the concave section and the less severe wave climate m thiS area The collapsed se::tlOns 'lf seaw,,:l could only be satIsfactonl) repaired by reconstructlO:' • bec&u~e a wall cross-sectIOn With a Wider base would be reqUired to comply With current rock witll practice It would also be necessary to backfill behind the wall with coarse graded • maten;li and to pro'. Ide a geotext: Ie filter layer between the retamed fill and the ba.;kftll • • Not~s made dunng the site mspxtlon carned out by MHL sraff are presented m Table 2 1 • fablt: 2.1 Seawall Inspection Chamage Comments • 0-19 Reasonable condltlon, !lee_is attentIon to crest F~ur cou~ses of rock Two bJttom courses approx 1300x5UOx400 h'gh, third course ~OOx500x2()() h'gh, top cocrse 'OOOx500x300 high • Bottom course straight on graveVmud 19 - 25 Coll~psed outwards • 25 - 34 Reasonable but bul,<>ng outwards 34 - 42 D'spiaG'!d out, erosion behmd • _-,-4=-2- 46 Collapsed outwards ______• continued! • • MHL670 -7 • • • Table 2.1 Seawall Inspection (continued)
• Chainage Comments 46 - 66 DIsplaced outwards, erosIOn behind • 66 - 84 DIsplaced out.... ards, top stones collapsed landward, level of crest low, extensIve erosIOn behind wall • 84 - 91 BU:r,lng outwards In mIddle, top fallen landward 91 - 99 Bulging outwards, top rocks hllen landward, some rocks In water, extensIve erosIOn behind • wall, crest low 99 - 111 Full heIght, reasonable condItion, top c')urse needs some attentIOn • 11: -128 badly collapsed outwards, f(Jcks In water, bad ~roslOn behind wall 120 - 126 Reasonable, top needs rebuIlding • 126-131 Bllapsed landward, extensIve erosIOn behind wall • 164 - 171 Wall bulging bc.dly, crest falhng landward 171 - 184 Wall bulging, e,tenslve landward collapsing of crest, crest low, exten31ve erosIOn SIX courses • Bottom and second courses 800x500x300 hIgh, thIrd course 600x500x300 hIgh, fourth course 600x500x300 hIgh, fifth and SIxth courses 900x500x300 hIgh Variable Irregular shape No • footing 184 - 196 Complete collapse, landward and outwards • 196-232 Crest rocks fallen landward, gIves bulging appearance, some crest rocks In mud 2m from wall 232 - 256 Wall reasonable, pronounced batter, crest a bIt low, some crest rocks In mud • 256 - 266 ExtensIvely collapsed, extensIve erosIon, rocks In mud but ~ome rocks must have been removed from site • 266 - 272 Reasonable, bIg VOIds between rocks • 272 - 27'( Reasonable but 20 % of crest rocks removed and In mud, top I')w Seven courses, 600x400x200 All courses SImIlar sIze SImIlar condition to Ch 353m 278 - 335 TC';> half of wall ~emoved and In mud, ext('nslve erosIOn A~pears to be flood scour, wall mu:t • have hen too lOW In thIs orea Bridge at 303m 335 - 353 Wall reasonable, large batter, top fallen landward, erosIOn/scour above wall • 353 - 358 Wall comr-letely collapsed, bank scoured 3m back Smaller rocks, 600x400x200 hIgh 358 - 364 Wall hulf collapsed • 3&- - 386 Wall :n reasonable condItion, crest low, scour above wall 386-417 Wall collapsed, roc"s In creek, bank scoured above remains of wall • 417 - 443 B0:t0l1l part of wall reasonable, some rocks removed 443 - <145 Culvert at Ch 1.. '4 Wall collapsed around culvert • 445 - 463 Wdl reru.anable, o"(.r~rown wIth vegetatlOll 468 - 472 Wall collapsed • 472 - 490 Wall .Iltact but has fallen landward, scour above wall 490 - 508 Wall collapseo, mangroves • 508 - 570 Oral'~e ~Jalnted naIl In pest at Ch 508 Wall low but reaso:lable condItIOn OVl!rgrown • Apprmamate end of wall at Ch 570 • The frulure mecham~m of the seawall appear~ to be that collapse has been brought about by the removal by erosion .)f fill matenal from directly behmd the wall Geotextile fabnc was • nut used behmd the wall when It was ongmally consu ueted and It IS rl)ssible for fill matenal • to escape thro loSh the gaps :)etween the roCk3 of the seawall ~/lSlhle remnants of geofabIH_ m • • MHL670 -8 • • • some sectIons of the seawall where repaIr work has been carned out mdlcate that geofabrIc has been used m repaIrs The repaIrs have however been unsuccessful f~b So,, ~ • ~-~ ~~~~ ~.JA1 • ErOSIon IS lIkely to have been caused by raInfall runof wave attack and seepage flow through the retaIned fill Because of ItS sandy nature the 1 WIll have a hIgh permeabIlIty and seepage • out of the fill WIll occur dUrIng and ImmedIately after raInfall events as well as dUrIng low tIde condItIons Dunng perIods of hIgh wave actIvIty wave~ wIll agItate the sandy materIal • behmd the seawall mcreasmg the rate of erosIOn At elevated harbour water levels waves wIll • be able to OV\!rtop the seawall causmg dIrect erOSIOn of the fill as well as mcreasmg sec-page • fiow back through the structure As fill IS removed tbe upper sandstone blocks progressIvely tIlt backwards applymg rotatIOnal • force or 'outward thrust' on t~e lower blocks ThIS mech.IDlsm IS shown m FIgure 2 2 aIld can be seen m Plate I The presence of rocks m the water m front of the wall as far away as 3m • may be due to wave actIOn or to vandalIsm WIth rocks havmg been removed from the wall and • thrown mto the water • Followmg IdentIficatIOn of the faIlure lnecham~m, more crItIcal mspectlOn showed that u: most cases even those sectIOns of the wall that appear to be In reasonahle condItIOn are • showmg early symptoms of faIlure WIth slIght landward dIsplacement of top rocks and a • bulgmg appearance of the wall • WhIle the eXlstmg seawall appears largely to have perfonned adequately from a structural vlewpomt, the present wall proportIOns are not adequate for current rock wall practIce It IS • therefore not practIcal to repaIr the present wall other than pOSSIbly by dumpmg rock on the outSIde of the seawall RepaIrIng the wall by thIS method would reqUIre the placement of a • geotextIle layer to prevent further removal of fill from behmd the eXIstIng wall Such a repaIr • would also probably encroach on the sIte boundary • 2.", Site Survey A strIP survey along the seawall to Chamage 500m (FIgure 2 1) was carned out by PublIc • Works Survey aIid Land InformatIOn SerVIces (SUS) The wall actually extf''lds to • ap;:-roxlmately Ch 570m, the last 70m bemg badly overgrown A plan of the seawall showmg the SIte boundaly and the alIgnment of the crest and toe of the eXlstmg seawall along WIth a • number of cross-sectIOns of the wall are shown In AppendIX A of thI~ repc,rt SUS holds large scale draWIngs 0'- the i>urvey whIch alSO show the locatIOn of survey marks that would • allow th .. set out of new ronstructIOE The ~urvey has heen catalogued by SUS a!: Plan Cat !.I No 9711 • Le :cls In the SUS survey and all levels m thu, report h:,ve been reduced to a datum 100 00r.l • below AustralIan Helgl.t Datum tAHD) • The ~urvey shows that the level of the !)laymg fieldo, behmd the seawall IS approXImately RL 101 5m , the level of the crest of the relatIvely undamaged sectIons of the wall vanes between • RL 101 Om ~l!Id RL 101 55m and the kvel of the toe of the seawall VaIleS between RL 99 2m and RL 99 9m The seawall lIes withm the SIte boundary wIth;} rmmmum clearance between • the seawall and the boundary of 0 4m at Ch 25 ~nd a maxImum cled.lance of about 3m at Ch • 165m • • • MHL670-9 • • • 2.3 Geotechnical Investigations Geotechmcal InvestigatIOns were carned out by Coffey Partners InternatIOnal Pty Ltd to • deterrmne the conditIOn of the eXistIng wall and footIngs, to determIne the soil profile behInd • the wall, to comment on the .>tabIlIty of the wall and to proVide foundation design parameters for wall reconstructIOn The full report descnbIng the Invest:gatlOns carned out IS presented • as Appendix B
• Geotechmcal InvestlgatlOn~ showed that the fill mateflal behInd the wall IS fine sand which has been placed rlirectly over recent allUVial sediments overlYIng Hawkesbury Sandstone to • form the reclaimed area The allUVIUm IS at least 2 2m thick Dynamic penetrometer • soundIngs were advanced up to 2 5m below th;: seawall footIngs Without encountenng t"~droGk The seawall appears to be founded on a var,ety of matenals l:J.cludIng allUVial • sediment" fine grmned fill ai1d coar2e blocky fill EXistIng beanng pressures are probably less than 50kPa Field observatlCns have not h,ghlighted any obVIOUS problems With the • beanng ('apaclty of the foundations, so wdll construclion along slUular lines to the- eXistIng • wall should not reqlare any sr'eclal fo:mdatlOn prepaf'ltlon • 2.4 Water Levels Design still water levels :or Sydney Harbour have been deternuned for other projects by MHL • based on Fort Deuson tide recurds for the peflod 1914 to 1990 (Austra:lan Water and Coastal • :-:tudles, 1991) The design still water level3 are ba~ed on the expected pt ak levels that are likely to occur over a designated return penod under the combined Influence of an • astrononucal tide and storm surge ThiS level does not Include wave set-up and wave run Up No allowance has been made for Greenhouse Effect The still water levels are shown In Table • 22 • • Table 2.2 Still Water Levels For Sydney Harbour Return Still Water Level • Period ReI. ISLW ReI. Survey Datum* • (Yrs) (m) (m) • 20 235 10143 50 239 10147 • 100 242 101 50 • * Survey Datum 100 OOm below Australian Helghc D1tu'll • The IT:axlmlJm :tormal L1d~ levd for Sydney Harbour (High High Water Solstl"e~ Spnngs) IS • applvx·mately 189m (rSLW) or 100 97m (Survey Datum) As notod ear!.er the g('nerallevel of t!->e playInt; field~ IS ~~ RL ; 01 5m whlc~ corresponds to the 100 year Retl,rn Penon still • water level There appears to be httle pOint In raISIng the "rest levd of the wall above chiS level as It Will .iffe::t surfacc" rur.off from the playmg fields However the wal: would be • o,ertopped by wave action dUIlng extreme conditIOns and measures need to be put In pla;:'e to • aVOid damage to the bank plotecilOn as well as to the fill matenal • Floods Will have no measllrable effect on the wate, levels of the e~tuarIne water body of T Mban Crcek beyond the entrancf.. to the actual creek due to ,he Width 0: the wale:- body • Dunn'_ site inspectIOns no IndlcNew South Wales, 1987) • PublIshed field mtasurements of boat geneiated waves are shown In T"ble 2 4 • Table 2.4 Boat Wave Measurements • Boat Type Maximum Wave Heighi Wave Period • (m) (seconds) • 15m Motor CHnsel 080 30 (Thackray, 1984) • 13m Tug 076 I 4 (Sorenson, (196~) • Speedboat 040 20 • (Leslelghter, 196:.lL) ____ • • • MHL670 ·11 • • • In addition, MHL staff have made a large number of observatIOns of boat generated waves on the Parramatta River Large vessel~ were observed to generate waves with penods between • 20 and 4 0 seconds with a large~t measured height of 0 5m and speedboats were observed to • generate waves With pen ods of less than 2 0 seconds With a largest measured height of 0 3m • The number of waves In a wave train was observed to generally number less than 10 Boat speeds wilhIn Tarban Creek wili be IIrruted by the 4 knm speed IIrrut within the • moonngs along both Sides of the waterway, by the narrow congested nature of the wa,erway • and by the Creek being a dead end for na'JlgatlOn • From the above informatIOn It IS e~t!mated that boat generated waves at thiS site Will be sIPalier than the largest Wind waves and Will have ~llrulm- wave penods to large Wind \\-aves • Boat waves ·.vIll, however, be able to approach the shore frcm a range of dlrecth)ns, mcludmg • normal to ~he shoreline • It IS oroposed that overtopp:ng of the seawall by waves be allowed for and that II concrete path 1500mm \~ Ide be constructed along the top of the' seawall [0 prevent scour Imm"dlately • behind the crest of the wall • 2.6 Currents Possible mechanisms for generatmg currents wlthm Tarban Creek are tidal circulatIOn, Wind • and flood flow from the creek Of these the only mechanism able to generate slgmficant • currents would be flood flow and then only m the area near the mouth of the creek InspectIOn of the bed near the creek entrance did not show any Significant scour of the bed which was of • slrrular composition to the bed near the toe of the seawall It was concluded that scour would • not pose a problem • 2.7 Construction Constraints Access to tb·;: site of the seawall IS through the grounds of the northern campus of Glad::sville • Hospital Some mmor Widening of the access track from the upper level of the site to the playing fiek!s Will be reqUired to allow large trucks to reach the site The area adpcen: to the • s;:awaJl proVides a large level site well s'uted to constructIOn of a site compound and the • stockpiling (If ma~enals aunng constructIOn wlthou~ major encroachment on the pi:lymg • fields E'lqUines were mude With the authonties listed below regarding the presence of services In • proximity to the seawall
• Water Board • MSB Waterway, Hunters Hill Council • Telecom NSW Health Department • Sydney Electnclty • Natural Gas Company • Replies were received from itll authontles No services were known to eXist In the Immediate • area of th-:: seawall The closest ~erv"e IS the W::ter Board sewag'! pumping statIO.) 0[1 the • • • MHL670 -12 • • • northern bank of the creek near the footbndge The locatIOn of the pumping station IS shown • In Figure 2 1 Because the seawall Ites wlthm the intertidal zone some components of constructIOn will be • affected by the tide Construct:on uSing lana based plant wIll be pOSSible when the water • level IS above the toe bl.t preparatIOn of the base and operatIOns uSing hand labour will not be • able to be carlled out at high water levels The seawall IS located In open space on ,he southern side of the creek but IS between 30m and • 170m from houses on the nvrthern bank of the creek Removal of the eXlstmg seawall and • constructIOn of a new seawall should not generate excessive nOIse levels No particular • advantage IS seen In any of the possible types of s'~av.all In terms of con~tmctlOn nOIse • • • • • • • • • • • • • • • • • • • • • • • • MHL670-13 • • • • • • 3. Options for Restoration or Replacement of • Seawall • 3.1 Introduction • The pnmary purt>o~e of the seawall IS to retam the fill underlymg the playmg fields It abo • protects the bank from damage by wave actIOn m the open area of Tarban Creek and from • flood scour m the creek sectIOn The design of the seawall will be affec~ed by the relatively poor foundatIOn conditIOns and the • reqUirement to allow dram age of groundw:::ter without the Icmoval of fi\: matenal It will also be necessary to protect the fooungs of the footbndge from scour by ensuring that the bank IS • protected from scour m thiS area The footmgs of the footbndge are approxImately 4m from • the toe 0f the bank • There are a number of seawall constructIOn options These may be broken down mto the baSIC claSSIficatIOns of slopmg and vertIcal (mcludmg steeply battered) structures and porous • or non-porou:> structures The SIte IS sUited to a porous structure because such structures • generally offer good dramage charactenstlcs and their mherent fleXIbIlity IS sUited to sites WIth relatIvely poor bearmg capacity A sUitable structure could be slopmg or vertical • (battered) although a slopmg structure Will encroach on the level area behmd the eXlstmg • seawall If ItS toe follows the alignment of the present seawall Beouse of t:le varIation m wave climate, WIth the bank only subject to substantial Nave • attack between Ch 80m and 230m (Figure 2 I), It IS ObVIOUS that the best solution may be a • composite scheme ... ,here the bank protection IS vaned along ItS length • POSSIVIe vertI~al structures mclude (I) gravity J.)ck seawall, • (II) gabIOn W111, • (III) cnb wall • Pos~lble SIO[lIng structures wlJuld mclude (I) stable beach, • (ll) np rap :.rmoured ~lope, • (lll) gabIOn mattress armoured slope • Detall~ of these pos~Ible or~IOns are listed below along With their advantages and dIsadvantages along WIth mdicative COStlIig to allow a comparison between the various • optIOns
• The mdlcatIv~ costs were developed assummg bank piOtectlOn 2m hlsh and 580m long • overall It was est.mated from the surveyed seitwall cross-sectloliS aed field measU"emcnts 01 • • • MHL670 ·14 • • • the seawall thickness that 380 m3 of sandstone rock could be recovered from the eXistIng • seawall, for re-use In some optIons and for disposal In others • Umt costs used m developmg mdlcatIve costIng are shown below Matenal costs shown • mclude cartage to site • Table 3.1 Unit Costs Bac!:fil:, granular $28/tonne, $50/m3 • 3 Backfill, plant and l.lbour costs, $3/m • Cnncrete, $ 120/m3 Concrete path, $50,1Inear m • Disposal of site mater, 11, $14/m3 (mcludm):\ excavdtlOn) ExcavatIOn, $2/m3 • Fill, for gablOns and r"no mattresses, $33/tonne, $60/m3 • GablOns, $47/m3 GablOn and reno) mattresses, plant and labour cosb, $60/m3 • GeotextIle fabnc for gablOns and reno mattJesses, supplIed and placed, $5/m2 GeotextIle fabnc for nprap, supplIed and placed, $7/m2 • Reno mattres~es, $52/m3 Sand, $ 19/torone, $30/m3 • 3 Sand, plant and labour costs, $3/m • Sarodstone blocks $1 I 501m3 Rlprap, $33/tonne, $60/m3 • R.Jprap, plant and labour costs, $5/m3 • It can be seen from the umt rates that two key Items that will have a large bearmg on the costs • of particular options arc the cost of sandstone blocks at $1 I 501m3 and the cost of disposal of • site matenals at $ 141m3 In additIon to the cost of the bank protectIOn a sum of $ j!) 000 has been allowed f('r site • establIshment a"d latel clean up, $30000 has been allowed for constructIOn of a C0n.rete p~th • and $t!0 000 has been allowed for supervIsIOn, survey tender GocumerltatJOn ,md contlngenc!(::s, a total of $80 000 for the total length of protectIon Thl~ amount has be("n • conver,ed to a rer metre pnce and mcluded m all costmg • 3.2 Option J - Rock Seawall • A seawall of sInular Cll IstructlOn to tbe eXlstmg seawall could he constructed However the proportIOns uf the present ~cawall are not adet;uate for current lOck wall practice ~nd a • replacement wall wOl.!d have t.) be wider at the base Two a!tematIve cross-sectlollS for a t'ry rock seawall are shov. n m Figure 3 I, one havmg a vertical front face: and the other a face • battered 1t a slope of 1 (hoflzo:1tal) to 2 (vertical) Both v. aIls have the s1Il1e cross sectlQn~1 area of 2m2 and hence reqUire .he same qU2'ltlty of rock It IS estImated that the present wall • 3 contaInS about 380m of rock The total quantity reqUired t'J reconstruct 580m of wall IS • '~stlmated at I 160m3 • Advantages Good dram -1 ~e • Inhere:1t fleXIbIlity • • • MHL670·15 • • • SlIrular appearance to present seawall and other seawalls m area Makes use of rock from eXlstmg wall • Does not take up extla space • MInimum excavatIOn • Mmlmurn dlspos;u of site matenals Disadvantages • Will reqUire additional (expensive) rock for adequate wall sectIOn • Re'-1U1res skilled labour • The Unit cost of a sandstone dry rock seawall Will vary With the krtgth of wall to be constructed For a length up to 190m It should be possible to CO:1struct the wall from rock • recovered from t:1e eXlstmg wall Beyond 190m It Will be necessary to either buy 111 sandstone blocks or to use concrete blocks behmd the face course of sandstone blocks • Beyond about 250m It would be necessary to buy sandstone blocks to proVide enougb • sandstone face blocks The cost of arty partlc'llar length of sandstone seawall Will therefore • have to be calculated lor that particular case Indicative costs for a full sandstore rock seawall are $495/m for a 190m wall and $20 10/m for • a 58Gm wall Costs for a sandstone roL.k faced seawall '-"Ith supplementary COl1crete blocks • are $585/m for u 250m wall and $ 1380/m for a 580m .vall • 3.3 Option 2 - Gabion Seawall • A typical gablOn seawall cross-sectIOn IS shown m Figure 3 2 • Advantages Good dramage • Inherent flexlblhty Could make use of rock from ex,stmg wall brc.ken down on site • Mamtams ex:stmg level area
• Disadvantages • Different appearance to other walls m mea Larger excavatlon than rock seawall • Prone to vandahsm(eg cutting of wires) • PossIble low,;r hfe expectancy due 'a corrosIOn • The mdt..1tlve cost of a gablOn seawalll~ $840/m • 3.4 Op!ion 3 - Crib Wall A typlc,,1 cnb wall coss-se,tlOn IS shown m rlgu.L ~ 3 A speCial cnb wall ~ystern for • milnne use IS aV
• The indicatIve cost of a reno mattress slope IS $442/m • • • • • • • • • • • • • • • • • • • • MHL670 -18 • • • • • • 4. Preferred Option • The. Indlcauve costs of the 0ptlonS considered In the last sectIOn are summansed In Table 4 1 • • Table 4.1 Indicative Costs of Seawall Options Option Length Cost/m Indicative Cost • (m) ($) ($) • Full Rock Seawall 190 495 94,000 580 2010 1,166,000 • Ro,;k Face Seawall 250 585 146,000 580 1,380 800,000 • GablOn Seawall 580 840 487,000 • Cnb Wall 5RO 629 365,000 Wide Beach 300 935 281,000 • Narrow Beach 300 675 203,000 Rlprap (creek) 330 450 149,000 • (wave area) 250 770 193,000 • 580 342,000 • Reno Mattress 580 442 256,000 The cheapest forms of bank protection are reno mattresses or nprap m the creek sectIOn at • basically the same cost of $450/m
• The next cheapest optIOn per metre, for a length of wall of 190m, IS the full rock ~eawall • constructed from rock recovered from the eXlstlr.g seawall, 2t a pnce of $495/m Above thiS length the pnce per metre mcred~e~ as It bc:comes I,~cessary to either buy rock for an all rock • wull or to use concrete blOCKS to st,pplemer!t a face row of rocks
• The preferred optIOn I~ " composlt,~ sd,t:-me compnsmg three types of bank protectIOn - • natural beach, rock seawall and nprap A plan vIew of the plOposal IS shown m FIgure 4 I The toe of the protectIOn would follow the aitgn'TIcnt of the toe of the eXlstmg seawalJ The • estimated total cost of protectIOn IS $309,000 • The detatls of the proposed protectIon IS outlIned bc:low
• Ch 0 - SOm • A n;:.tural bedch would r(!place the eastern end of the eXlstmg sea\Vall from Ch 0 to Ch SOl:' In thIS area the level area behInd the wallIS relatively narrow (approxImately 10 - ::!Om) and IS • not used as part of the playmg fieids ThIS part of the foreshore IS also relatl vely sheltered from wmd waves and adJo,ns a Sf'ct'on of shorelme to l~le east contaInIng pockc'_s of saI,dy • beach among area~ of roC! It IS envlsa2,ed tlJat the beach would form a contmualIOn m • appearance of thI~ shr/relme The beach to t~,e east backs onto large natural rocks nsmg • steeply from the slopIng beach The eont!OuatlOn of the Ime of rocks can he seen at the b:lck • • MHL670 - 19 • • • of the level area and It should be possIble to construct the beach wIthout a wall or pathway at the rear It wIll however be necessary to construct a draIn along the back of the beach to • replace an eXIstIng open dram The estimated total cost of the beach area IS $41 000 mcludmg • the dram at the back of the beach • A typIcal cross-sp-ctInn of the beach IS shown 10 FIgure 4 2 The beach should be constructed \vlth a ma>..Imum slope of approximately I 10, slflular to areas of beach to the eas. The dram • at th~ rear of the beach could be constructed from reno mattresses as shown 10 FIgure 4 2 WIth • rubble fillmg 10 the space between the mattresses and the natural bank The gradmg of ~and used In the beach shuuld ve chosen so that It IS not finer than sand 10 the areas of beach to the • east • Ch SOm - 300m A ~ ..mdstone seawall slIrular 10 appearance to the eXlstmg seawall IS pr'Jposed between Ch 50 • and the foutbndge at Ch 300 By lImiting the length of wall to less than 250m It ~hould be • pOSSIble to construe' It from sandstone blocks recovered from the eXlstmg 'icawall WIth concrete biocki' placed 10 the rear course of the wall to make up suffICIent blucks Pus • sectIon of seawall IS 10 the area subjected to the most adverse wave clImate and IS the most vISIble sectIOn of the seawall It IS also the area closest to the marked soccer fIelds and a • vertIcal seawall wIll maIO tam the present dIstance from the soccer field to the water's edge • The footbnd~e wIll proVIde a pomt of VISual demarcatIOn between the creek and estuanne • sectlcns of the bank protection The estImated cost of the seawall section IS $146,000 The rock wall should be constructed 10 the manner shown 10 FIgure 4 3 Rocks should be • placed 10 such a manner that they are stable and mterlockIng and laId roughly coursed and bedded on the broadest base Where rocks cannot be bedded 10 a swble manner because of • theIr shape they may be laId 10 a bed oi mortar However, the use of mortar should be lImIted • 10 order to mamtam the free drammg propertIes and fleXibilIty of the structure Rock IS to be of sound durable sandstone or other approved matenal With a mmlmum dlmen'IOn of 0 Sm • Backfil: IS to be granular, free dram 109 and ccmpacted Weepholes are to be prov!ded by SpaC1'1g blocks WIth 20-S0mm gaps A geofabnc combmmg hIgh tensIle strength and Stlffness • WIth good filtratIon capacIty, such as Propex 3220 (A.moco ChelllJcals) should be used under • and behmd the wali and b~tween the coarse free draIntng backfIll and the ~andy fIll of the • reclaImed area Ch 300m - Ch S70m • A f'prap slope 1S proposed fOi the creek section from Ch 300 to Ch 570 T;ll~ sectIOn IS .10t exposed to suhstantlal wave attack '1nd Its malO purpose IS to protect the bank from flood • t~le ~Iprap • scour The estImated cost of protectlcn IS $122 000 Based 0:1 thp ~e('ommendatIOns of Rural Water CommissIon of VlctOtla, 1991, the DSO :Ize ()f • nprap IS 200 mm The recommended gradmg of rock fO! the nprap protection IS shown 10 • T(lble 4 2 • • • • • • MHL670 - 20 • • • • Table 4.2 Riprap Rock Grading • Equivalent Sphere Diameter Rock Mass % Smaller by Mass (mm) (Kg)* • 400 77 100 200 10 50 • 60 08 10 • * Based on specific gravity of 2 3 • There should be no signIficant vOids 'n the rock nprap through which underlymg matenal • could be washed out and no llIdlVldual rock should be free to move by Itself • Rock used m the nprap shall meet the followmg reqUirements • I) All rock shall be hard, durable and clean rock from a quarry (or qllilrnes) approvf'd m wntmg as a supply source by the works supenntendent and be stnct~y m accordance with • any conditions of that approval The rock shall be resistant to abraSIOn dnd free from cracks, cleavage planes, seams and other defects mcludmg unstable mmerals which • could result I11lts breakdov,n under a manne environment ll) "II rock shall have a Los Angeles Value of not more than 25% • lll) All rock shall a sodium sulphate test result not exceedmg 12% loss • IV) All rock shall have a m!mmum speCific gravity of 2 3 v) All rock shall have a saturated unconfined compressive strength greater than 50MPa • VI) All rock shall have a mlmmum wet/dry strength ratio greater than 50% Vll) All rock shall be of such a shape that the maximum dlmen~lon does not exceed 2 5 times • the nummum dimenSIOn • A geotexttle underlayer shall be proVided between the embankment af'd the nprap ThIS • geotexttle IS to ha,,~ a umt mass greater than 350g/m2 (eg Bidim A64 or Terrafix 369R or slnular) and should be moved, Jomed and placed m accordance WIth the manufacturers • speCIficatIOns Care must be taken to ensure maXImum re~lstance between the nprap and the geotextlle ".0 ensu:e thIS It IS recommended that the bank not be prepared to a smootl, even • batter before placmg the geotextIle and that the geotextIle IS not ~tretchea tIghtly over the • bank Scour protectIOn should be proVIded at the toe by placmg extra rork a5 a 'self launchmg toe' ~hould tht: wall be uncier:ut Tne geotexttle fabnc should extend underneath all rock • plac;.:d at the toe such ,hat the as the rock IS 'launched' mto a new pOSitIOn It will contmue to • be underldm by the geotexule • The alIgnment of ti !(, toe of the nprap IS to ,emam wlthm the alIgnment of the toe of the • EXlstmg seawall The crest alIgnment shnuld be a ~mooth cune • • • • • • • MHL670·21 • • • • • • 5. Conclusions and Recommendations
• The eXistIng seawall has reached the end o. Its usefulhfe and IS beyond rep!'.1r To rebuild the • wall to modem deSign standards over Its present length would reqUlrr the purchase of addItIOnal rock to rruse the crest level and to thlc~~en the base of th(' wall Because of the high • C03t of sandstone blocks alternatIve structures were InvestIgated • FollOWIng assessment of alternative structures a c0mposlte deSign compnsIng a beach, a • sandstone seawall slfnIiar In appearance to the eXistIng seawall and nprap protectIOn IS proposed ThiS scheme Will IIllmrruse the cost of protectIOn while maIntaInIng a slllular • "ppearance In the area most exposed to publIc view • The crest of the prOtectIOn has been set at RL 10 I 5, the level of the plaYIng fields and the 100 year average recurrence Interval stIli water level for Sydney Harbour No prOVI::IOn has been • made for sea level flses associated With the Greenhouse Effect A concrete path, 1500mm • Wide should be constru~ted along the crest to proVide protectIOn from overtoppIng that could occur due to wave actIOn combIned With high water levels In the area of the seawall and from • the po-slbllIty of flood scour above the nprap protectIon In the creek area
• As the cost of the sandstone rock seawall sectIon of the proposed bank protectIOn IS highly • dependent upon recovenng suffiCient SUitable sandstone blocks from the eXistIng seawall to construct the VISible front face of the seawall It IS recommended that confirmatIOn of the • quantIty of blocks be made a condition of tendenng • It IS lIkely that the deSign of bank protection along Tarban Creek wIll be affected by the overall dral'1age deslgl' for the redevelopment area D, runage outlets wIll have to be • accomm0dated WithIn the bank protectIon and protectIOn from scour provlried at the toe of 'he • structl.,"e From the POInt (·f view of the bank protectIOn the best lecatlOns for dra,.lage outlets are In the Cleek upstream of the nprap protection and on the rocky beach area to the east of the • propo-ed beach It IS recommended that the overall site dramage be deSigned so that • discharges are diverted aw~y from the bank prote,;tIon • • • • • • • • • • MHL670 - 22 • • • • • 6. References
• Australian Water and Coastal Studies Pty Ltd, 1991, DeSign GUideLmes for Water Level and • Wave Cltl"'la!e at Plttwater, Report 89123 • Coast~! Engmeenng Research Centre (CERC), 1984, Shore ProtectIOn Ma:v.al, Fourth • EditlOn" DepartmeI!t of !he Army, Waterways Expenment StatiOn, Corps of Engmeers • Leslelghter E J, 1964, Hawkesbury River - The Effect of SpeedIJoat Activities on Bank • EroSIOn, Manly HydraulICS Laboratory, Report No 276 • Maritime Services Huard of New South Wales, 1987, Fore-and-Aft Moormgs Study • Melbollme W H, Extreme Wmd Gustsfor Sydney, Report to Ove Atup and Partners • Rural Water ComellsslOn of Vlctona, 1991, GUidelines For StabilISIng Waterways, Standmg • Comrruttee on Rivers and Catchments, Vlctona • Sorenson R M , 1967, InvestigatIOn of Ship Generated Waves • Thackray M A, 1984, FLoatmg Breakwater Performance, Master of Engmeenng SCience • ThesIs, Umverslty of New South Wales • • • • • • • • • • • • • • • MHL670 - 23 ·• .------~ • • • • • • • • • • • • • • Looking west. Trundle Wheel at Chainage 81m • • • • • • • • • • • • • • Looking east. Trundle Wheel at Chainage 190m • ~--~--~~~--.------~----~ • ~ State Projects Plate Manly Hydraulics Laboratory EXISTING SEAWALL 1 • Report No. 670 • • • • • • • • • • • • • • • • • • • • • • • • • Looking west. Trundle Wheel at Chain age 286m • • • • • •
• ~ State Projects Plate • Manly Hydraulics Laboratory EXISTING SEAWALL 2 • Report No. 670 ..
M.tr.s 0 100 200 100 400 500 SOD 700 aoo 900 1000 Metres .. ~~~~~~_:E3~::F3:~C~~~~~TO~uE3~R~IN~T~E~~V~Al:~~4~M~ET~RE~f3~~~~~~-~~~ __~~~~~~~~~~~~ .. State Projects Manly Hydraulics Laboratoryl SITE LOCALITY PLAN 1.1 .. No. 670 •.r------~------~------~ • • • • • , , , • , • \
• I • I I I • I U) I 0 I -' • w • I "e LL I tf • I c.!) I Z ~ • ~ >-
• 1 • Minor erosion of fill Backtlltlng block __ f-- ~ ,------• -=-..-:. .. ":;:...... • .' FILL Fill earned away by • groundwater flow
• SEDIMENT • • • • • 2 • FILL • • SEDIMENT • • • • 3
• FILL Eroded fill", • " •
• SEDIMENT • ----- • •• • • .~~~--=-~--~------. • ~ State Projects i Figure Manly Hydraulics Laboratory CONCEPTUAL FAILURE MECHANISM 22 • Report No 670 •
500 min
Concrete path RL 101 Sm 11 / .. "I I, Sandstone blocks /GO.,.,'" "'~~~~ 8o N r Granular backfill
Geofabnc I. 1500 min .1
VERTICAL FRONT FACE
Concrete path RL 101 Sm / f I __ Geofabnc 81 • ~I Sandstone blocks --..r-..:":=:=~~=~l I • I j • I • ~ Jf • • • RATTERED FRONT FAGE • • • •1--==------:------.----- • ~ State Projects OPTlm.. 1 - ALTERNATIVE TYPICAL ROCK SEAWALL I Figure • Manly Hydraulics Laboratory CROSS-SECTION VERTICAL FRONT FACE I 3 1
Report No 670 AND BATIERED FRONT FACE ' ___ 0 __ , __ •.,~------~ • • • • • • FI~er cloth • RL 101 Sm • • •
• Gablon Granular backfill • I • I
• !810 IN • I • I Gablon • Gablon • • ------• yI • • I • 2000 • I~ ---~ • • • • •
•~~=------~-----~------~-F~lg-u-re~ • ~ State Projects OPTION 2 - TYPICAL GABION SEAWALL 32 • Manly Hydraulics Laboratory CROSS-SECTION Report No 670 • • • • • • Concrete path • Filter cloth • \ • •.' • • • • • • • • • • .,• • • • • • •.1 .! ·1" • rl~·-:::;;;;;;;;;;;;;]~S;::-t-a-te--:P=-r-o-~e-c-ts-'------Figure • Manly Hydraulics Laboratory TYPICAL CRIB WALL CROSS-SECTION 33 LReport No 670 ·'~------I
10 PlaYing Fields
RL 101 Sm
~_---___- ______~20~m ______~
WIDE BEACH
• • RL 99 Sm
• I 1l'm • ~- • NARROW BEACH WITH WALL .'• ~I • • • • Figure ~ State Projects OPTION 4 - ALTERNATIVE STABLE BEACH • Manly Hydraulics Laboratory 34 Report No 670 CROSS-SECTIONS • 0'1 "'NG to> , fib .. "o~" •
Concrete path :iL 101 ------5m
"'Filter Clt)th
.~ State Projects • Manly Hydraulics Laboratory OPTION 5 - TYPICAL RIPRAP CROSS-SECTION Report No 670 •
Concrete path RL 101 Sm ------~==~~~~r------
Figure OPTION 6 - RENO MATTRESS ARMOURED SLOPE 36 •
-_oI-~~Z
, \
, I rJ) ,, 0 , -'w , ~ ~ LL a..
(!J , -Z I ~ >- « , a.-' I
E a W S > :.c lU w If, f- W ":2 co: X 0 ([ a. CL
W" -' 0 (/j"
I J
Figure Laboratory PREFERRED OPTION - PLAN LAYOUT 4 1 .~------~
Maximum slope
10 Natural bdnk
Min 500
Na~ bed ll~::~ ____ --~lm:p:o:rt3ed~s~an~d~======~======-
~==~~------~----'r------Figure ~~.. State Projects PREFERRED OPTION - TYPICAL BEACH Ma:lly Hydraulics Laboratory CROSS-SECTION 42 Report No 670 .~------~
Concrete path RL 101 Sm . . /
o o o _'7--Coarse. free dralnln,] N granular baddlll
'. ~O'~~~~o==;:o~~o:==;;;==:;;:=:===~~~ Concrete blocks where necessary ° 00 ° 0
Cravel footing
lS0Gmin ~
• • ~ State Proje~ts PREFERRED OPTION - TYPICAL ROCK SEAWALL Manly Hydraulics Laboratory CROSS-SECTION CHAINAGE 50 TO 300m • Report No 670 ___h:c'"'~" .~,-~g,~. .~------~
RL 101 Sm, ______--- Rlprap minimum thickness 400m ---
"Geotextlle underlayer
• •, • • • • • , •.1 '----====------,------1 Figure • ~ State Projects PREFERRED OPTION - TYPICAL RIPRAP I 4 4 Manly Hydraulics Laboratory CROSS-SECTION CHAINAGE 300 TO 570m I • Report No 670 • • • • • • • • • • •
, • i.I • • •
• Appendix A '.• Site Survey • • • • • • • • • • • • • • • 0 1 00-- • .'• • ~~ • ~'V • G~ 0("\
• OS, • -Y-J ,
• 0 • 2 V1 w M) if) n: • @ "- ,- @§ w ~ ::;: • i@ @, 01 • @ Lf) ~ yo w ~ ...J • if) « © N U • d V1
• 0 • • • • • • • , , : I , I • I I • I I I • I • I
~ ~ -~~~ ~ .... ~ ~ ~ • ~ www.... > 1ft VI VI ~ • 10200 -~------, I , 1 I 1 I 1 • I 1 I • 1 rL-I 1 1 Z ,0100 +------1------j------t-"l • 0- 1 1 I 1 f- 1 1 1 1 • 0 0 0 o ex;, • 0 0 0<-0 0 Lf) • 0 0 Lf) Lf) • CHAINAGE 00 • I • • • • • • • ~State Projects Figure • Manly Hydraulics Laboratory CROSS SECTION - CHAINAGE 00 A2 Report No 670 • ORA-..:I .... T-.oowo • • • • • • • • • • • 10200 ,------1------1- --- -1---- -1-1 I IJ I I I : I • 1 I I I I I , , ---1 _____ --1J • 10100 1------1------I I I : : I II • Z I , 0 j I I ! I - I I I I I • I- o o o o ON • o o 0<0 o o o UI o UI 00 • NN • CHAINAGE 50 • • • • • • • • Figure ~ State Projects • Manly Hydraulics Laboratory CROSS SECTION - CHAINAGE 50 A3 • Report No 670 • • • • • I • • • 10200 ------1------'I - - - - -, • r 1 I I 1 1 --, • 1 __ ------r- I i I I • 10100 ~------!-- - -I------! -- ---I 1 I: • 1 I, I 1 ,: • Z 10000 C' - ~l· -----~------1----~ • '- « • ~.-- W 9900 --.J -----i- ---~-----~----~ I 1 I i • W 1 I I : • 1 I 1 I 1 ill • 9800 ------1------1- - - - -1- - - -I 1 I I I • I I I 1 I I I I I 1- 1 ill • 9700 0 en -..1 " -..1 '"<.D (J1 '" I'- "" - 0 0 • (J1 ""(J1 S? 0 0 0 0 0 • 0 0 0 "- 0 0 en • S? '!2 ~ • CHAINAGE 100 • • • • • • • • ~State Projects Figure • Manly Hydraulics Laboratory CROSS SECTION - CHAINAGE 100 A4 • Report No 670 • • • • • • • • • • 10200 r------1------1 • I i 1 I • I 1 1 1 • 10100 i------I------iJ------~ I 1 1 • I 1 1 z 1 0 1 1 - I 1 1 • f- « 10000 f------I- --- f--j------i • > ! 1 1 I w I 1 1 --.J • w I 1 1 1 1 1 • 9900 ------1- ---1------1 I 1 I 1 • I I I 1 I I I I I I • 9800 I -..r ro 0 r-- N ill- ro ro - (J) 0 • (J) SO 0 0 0 0 .:> • 0 0 0 0 -..r 0 If) • 0 '!: ~ • CHAINAGE 120 • • , • • • • • • Figure ~State Projects • Manly Hydraulics Laboratory CROSS SECTION - CHAINAGE 120 AS Report No 670 • ~""T-...rwtM • • • • • •., • • • • 10200 • r-----~----1----1-----~-, 1 1 1 1 I ______1 _ ____ ~______---l ___~ __ -L_J • 1C100 1 1 1 1 1 • 1 ! 1 1 I Z , 1 Iii 0 - 1 1 1 1 • f- o o o ("1 • o o o 0 o 0 o en o '"_ • 9 l£2 N N • CHAINAGE 1S0 • • • • • • • • ~ State Projects Figure • Manly Hydraulics Laboratory CROSS SECTION - CHAINAGE 150 A6 • Report No 670 • • • • • • • ·1• • • • • 182 DC ~ ------p ------I I I I I I • I I I I _ I -I , I I I I I • i I I I 1 1 Z 10100 1-----1------1-t-----+ ------+--1 o • I I I : 1 1 f I 1 I I 1 1 0 0 0 0 0 co • a 0 0 0 0 ill Lfl a Lfl a S' N- • " • C'HAIN,lI,GE 200 • • • • • • • • ~State Projects Figure • Manly Hydraulics Laboratory CROSS SECTION - CHAINAGE 200 A7 • Report No 670 • • • • • • • • .'• • • • 10200 1------,------,---1 • 'I ~ 1 J • I ,-/V :: Z 10100 f------1- --- -/------T -- -, • o ! ! I f-- 1 ! I « I : I • > t I ~ 10C 08 -f------,------, - --1 • w ' II • 1 I I ~I I I I I I 9908 • N U1 U1 0"1 N l.O N ~ U1 0"1 en a a a • O"l en a a a a "- • a a a a a a U1 • 2 'D S!'! • CHAINAGE 250 , • • • • • • • • • ~State Projects Figure Manly Hydraulics Laboratory CROSS SECTION - CHAINAGE 250 A8 • Report No 670 • • • • • • • • • • • • • 10200 • • rn--r----T ,:--1 --I Z 101 DC ~-----I-----~-~---~---~ o • 1 1 1 I f I (\ ! .) I I 0 0 0 0 ~ • 0 0 0 0 ~ 0 ~ • 0 '!2 S? • CHAINAGE 260 • • • • • • • • Figure ~ State Projects • Manly Hydraulics Laboratory CROSS SECTION - CHAINAGE 260 A9 • Report No 670 • • • • • • • • • • • 10200 ~------I --1------1 I 1 1 • 1 ' I • 10100 • z t-----~----~-----~--~ o • I I 1 ~ 10000 ------1------1------' -- -j • > 1 1 1 W 1 I 'I ---.J • W I ,I II! 1 • 9900 • J1V- --- T---- r----l --I • 98 C8 . I I I I • 0 0 0 o o • o o 0 0 U) 0 0 -.r o U) • S' '!! " • CHAINAGE 300 • • • • • • • • Figure ~State Projects • Manly Hydraulics Laboratory CROSS SECTION - CHAINAGE 300 A10 • Report No 670 • • • • • • • • • • • • 102 Ole • • z 10100 o • f-- • 9900 (J) co CJ ~ " CJ 0 • 0 0 0 0 0 0 • Figure ~ State PrOjects • Manly Hydraulics Laboratory CROSS SECTION - CHAINAGE 350 A11 • Report No 670 • • • • • • • • • • • • 10200 ~------, I 1 1 1 • 1 1 1 1 • : /: :: z 10100 ------1------j------j-- --I • o 1 1 1 1 1 1 1 1 • 1 1 1 1 • 10000 t------: ----~-----~---: 1 1 1 • 1 1 1 1 1 I • 9900 I I I co :::> • 0' :::> :::> :::> 0' :::> :::> :::> :::> r-- • :::> :::> :::> :::> co U) • :::> :::> U) s::: • CHAINAGE LOO • • • • • • • • ~State Projects Figure • Manly Hydraulics Laboratory CROSS SECTION - CHAINAGE 400 A12 • Report No 670 • • • • • • • • • • • ,0200 1------1- -- -: 1 1 1 • , 1 -j 1 1 I___ J • 10100 1----- 1 1 • z 1 1 0 1 1 - 1 1 • f--- f------<1: 100 00 --1-----1 • > 1 1 w ---.J • w • 9900 LI~~i~~~- 1 1 • 1 ! 1 1 • 98 00 1 0 0 • 0 0 0 • 0 en ao • CHAINAGE L50 • • • • • • • • Figure ~State Projects • Manly Hydraulics Laboratory CROSS SECTION - CHAINAGE 450 A13 Report No 670 • 1lfU, ..."" .... t_D'IW • • • I • • • • • • • • • • • 10200 • T-----;--- ~-~ z ' 1 l • 0 - f- 10100 ~ • • Figure ~State Projects • Manly Hydraulics Laboratory CROSS SECTION - CHAINAGE 500 A14 Report No 670 • """ ...... _1~ • • • • • • • • • • • • • • • • • AppendixB • Geotechnical Investigation • • • • • • • • • • • • • • • • • • • • • • • • • • • • Public Works - State Projects • MANLY HYDRAULICS LABORATORY • GLADESVILLE HOSPITAL SEA WALT~ • GEOTECHNICAL INVESTIGATION • S9986/l-AB September, 1993 • • • • • • • • • • • • • • COffEY • • Coffey Partners International Pty Ltd Consulting Engineers • In the Geotechnical SCIences • • • • COfflY • Coffey Partners International Fty Ltd C(>"sultln9 EII9lneers .-- A C N 003 692 019 In Ihe Geolechmcal SCiences • 12 Waterloo Road "Jorth Ryde Sydney 2113 • PO Box 125 Your Reference North Ryde New South Wales ~9986/l-AB NSM LM Au,:raila 2113 • Our Pderence Dat£' 15 September, 1993 Fax (02) 888 9977 • Telephone (02) 888 7444 • • The Manager • Pubhc Works - State Projects Manly Hydrauhcs Laboratory • I lOB King Street • MANLY V ALE NSW 2093 • • ATTENTION MR BOB COOK • Dear Sir, • • RE: GLADES VILLE HOSPITAL SEA WALL • Attached IS our report on geotechnical Investlgatlons for the Giadesvllie Hospital sea wall on the • southern bank of Tarba\n Creek • Please don't heSitate to contact me If you need to diSCUSS any aspects of thIS work • For and on b:::half of • COFFEY PARTNERS INTERNATIONAL PTY LTD • • • • N S MATIES • • • Soli and rock engmeerlng EnVironmental technology Engmeenng geology Offices and NATA RegIStered Laboratones • Groundwater hydrology Adelaide Albury·WOOonga Aistonvllie Foundation englneenng Bnsbane Canberra Gostord Logan City Mmmg geolechmcs Melbourne Newcastle Pennth Perth Dam engmeenng Sydney Townsville Wollongong • Computer applications • ConstruCtion control & momtonng Bangkok Kuala lumpur Manila • • CoU",y Part"ers International Pty L:d • S9986/l-AB • J 5 September, 1993 • ------• • CONTENTS • PAGE • INTRODUCTIOl" 3 • l.0 • 2.0 FIELD WORK 3 • 3.0 SITE CONDITIONS 4 3 1 Surface CondItIOns 4 • 3 2 Subsurface CondItIOns 4 • 4.0 DISCUSSION AND RECOMMENDATIONS 5 • 4 I Site Model 5 • 42 Failure Mechamsm 6 43 Footing ReqUIrements 6 • 44 Sea Wall ReconstructIOn 6 • • Important Information About Your Geotechmcal Engmeenng Report • Drawmg S9986/1-1 Details of InvestigatIOn • Photographs 1 and 2 • • AppendIX A - GeologIcal Logs of Dnll Holes • • • • • • • • • • • • • Coffey Partners Internutlonal Pty Ltd • S9986/1-AB .---• 15 September, I q93 3 • • 1.0 INTRODUCTION • This report descnbes geotechnical studies caflled out for the NSW T)epaltment of Health on tlJe • proposed recsnstructIon oj a sea v,all along Tarban Creek at Gladesvtlle Hospital, Sydney • This work was c.ommlsslOned by Mr Bob Cook of Manly Hydraulics Laboratory, Public Works • Department - State Projects on 31 August, 1993 • The purpose of the ~tudles 'vas to Investigate the conditIOn of the eXistIng wall and footIngs, determIne the sOil profile behInd the wall, comment on stability of the wall, and provide • foundatIOn design parameters for wall reconstruction • PrelimInary informatIOn consisted of a scope of work statement and survey plan of the sea wall • provided by Mr John Murtagh of Public Works • • 2.0 FIELD WORK • Field work consisted of • • logging of 4 power auger boreholes together with dynamic penetrometer testIng, to • maximum depths of up to 2 7m for augered boreholes and 3 9m for penetrometer tests • • a detailed walkover inspectIOn by one of our Pnnclpal EngIneers • ThiS work was carned out between the 2nd and 13th of September, 1993 The log are presented • In Appe,ldlx A, together with explanatIOn sheets definIng the terms and symbols lIsed In their • preparatIon • LocatIOn of boreholes are shown In DrawIng N0 S9986/ I-I They were obtaIned by paced • measurements from eXistIng surface features shown on the supplied plan Ground surface levels • were not measured • Water level readIng have been made In auger hole before backfilling, and levels ale shown on tbe logs It must be noted that fluctuations m groundwater level Will occur due to vanatlon In tides, • rainfall, temperature and other factors • • • • • • • Coffey Partners International Ply Ltd • S9986/l-AB .--• 15 Septe mber, J991 4 • • 3.0 SITE CONDITIONS • 3.1 Surface CondltlOn~ • The sea wall IS approximately J to 2m high, with face b~tter ranging from vertlcdJ to about • 2V IH, and runs for about 600m 210ng the southern bank of Tarban Cleek An uneven, b.1t • approximately honzontal grassed playing field lies between the sea wall and the flanking slope • leading up to Victona Road The wall IS constructed of dry stacked Hawkesbury Sandstone blocks, with dllnenslOns of about • o 7m X 0 5m x 0 3m Several parts of the wall have collapsed or partially coll~psed, and matenal • has been eroded away from behind the wall for distances of up to 3m • 3.2 Subsurface ConditIOns • The site IS Situated on recent allUVial sediments overlYing Hawkesbury Sandstone and tYPically has • a subsurface profile consisting of • TOPSOIL SAND fine gravel, dark grey, some slit, root fibres • o 15 to 0 2m thick • • - above - • FILL SAND fine to coarse grained, grey and brown grey. some slit, some I 2m to 185m fine thick gravel Very loose to very dense consistency • Note coarse fill generally found Within I-2m of the sea wall and at • about 0 8m depth In the area of borehole TC2 • - above - • ALLUVIUM CLA YFY SAND fine grained, dark grey, trace of shell and wood • greater than 2 2m thick fragments • Minor amounts of SANDY CLAY medIUm plastiCity. dark grey, shell fragments and root fibres • Generally very loose consistency, With a medium dense layer at the • FILL! ALLUVIUM Interface • • • • • • Coffey Partners International Pty t td • S9986/i-AB • 15 September, 1993 5 • • • The profile IS based on power auger holes drilled on the plaYing field approx!mately 4m b~hlnd the sea wall Observation of eroded faces Immediately behind the wall suggests that coarse fill, • Includl.lg sandstune cobbles, has been used Immediately hehlnd thi> wall but It IS possible thi!, thl~ • IS matenal whIch has been placed to repair areas subject to erosIOn froll' surface run-of;, and • hence may not eXist for the full length of the wall • Groundwater was encoul'tered at j I to I 2m below ground level, which IS approximately 02 to o 5m above the sea wall footIngs The tIde was nSIng dunng the penod of field work, water • levels In Tarban Creek were estImated to be between low and mldwater Dunng a subsequent • inspectIon at low tIde after a rain penod, Significant seepage flows were observed to be c0mlng from the toe of the wall at numerous locatIons There IS also a concentrated subsurface draInage • outlet In an eroded area about 50m west of the footbndge, which was flOWIng freely after the rain • penod • 4.0 DISCUSSION AND RECOMMENDA TIONS • 4.1 Site Model • Fill matenal consisting mostly of fine sand has been placed directly over alluvial sediments to • create a reclaimed area presently utilIzed as a playing field The sea wall was built around the fill • to protect It from erosIOn and probably to InitIally retain the fill matenal • AllUVIUm IS at least 2 2m thick DynamiC penetrometer soundings were advanced up to 2 5m • below the sea wall footings wIthout encountenng bedrock • The sea wall 'lppears to be founded on a vanet) of matenals, IncludIng • • allUVial sediments (e g TC4) • • fine grained fill (e g Tel & TC3) • • coarse blocky fill (e g TC2) • The sea wall IS constructed of a Single row of sandstone blocks, stacked I m to 2m high EXisting • beanng pressure, are probably less than 50 kPa • • • • • • • • Coffey Partners International Pty' Ltd • S9986/1-AB • 15 Septerr'bE:.r 1993 6 • • • 4.2 Failure Mechamsm • Tb'! sea wall appears to be collapsing because of removal by en.3lOn of fill malenal from clrectly • behind the wall As fill matenal IS removed :he upper sand~tone blocks progressively tilt backwards applYing rotatIOnal fOice or 'outwards thrust' on the lower blocks This mechanism IS • sketched on Drawing S9986/1-1 The noslOn IS probably caused b/ both wave effects from Tarban • Creek, and seepage flows out of the retained sandy fill, the latter would occur particularly after extended penods of rainfall, when an elevated groundwater table can be expected to develop In the • fill, which because of ItS sandy nature Will have a relatively high infiltratIOn capacity Photographs • I and 2 show typical eXdmples of early and late stages of wall detenoratlon • Failure may also occur because of undermining of the footing blocks by erosion of foundation • matenals, but this mechanism can not be canfirmed or discounted without inspection of footing • blocks exposed at low tide Nevertheless. there IS no obVIOUS eVidence of any problems With the footings, either from erosIOn or beanng capacity viewpoints • It would also appear that the wall has suffered Significantly from vandalism over the years, With • rocks being removed from the top of the wall and thrown Into the creek, (to either splash or splat, • depending on the state of the tide) I • 4.3 Fooling ReqUirements • The eXisting wall beanng pressures are probably about 50 kPa Field observations have not • highlighted any obvIOUS problems With beanng capacity of the foundations, so wall reconstructIOn • along Similar hnes to the eXisting wall should not require any speCial founddtlOn preparation • 4.4 Sea Wall ReconstructIOn • In reconstruction of the seawall, the fC'llowlng pOints should be noted • • while the eXisting wall appears largely to have performed adequately frOlil a • structural VieWpOint, the present wall proportions are not adequate for current rock • wall practice For a 2m high wall a base Width of at least I m, and preferably 15m, should be adopted, while for a 1m high wall, a base Width of at least 075m • IS reqUired A top Width of 0 5m will be sallsfactory For walls of these • • • • • • • Coffey Partr>ers International Pty Ltd • S9986/l-AB • 15 ~eptember, 1993 7 .------• • proportions the front face can be either vertical, or battered no flatter than 2V IH • • geof:tbnc should be used to prevent the erosIOn of matenal from the base of th~ • In In wall, to assist bndglng over localised soft spots the foundation, ar.d to prevent • the erosIOn of the retained sandy fill A geofalmc combining high tensile strength and stiffness with good filtratIOn capacity, such as Propex 3220 (Amoco Chemicals) • should be used at the base of the wall In particular Any backfill between the wall • and the geofabnc-protected sandy fill should be coarse, free-draining granular • matenal • • It would be pOSSible to use some other form of retaining wall to prOVide the physical constraint, with the sandstone blocks being used as a facade A wall • system with Inherent fleXibility, such as a cnb wall, would be preferable, given the • relatively poor foundation conditIOns for a reinforced concrete structure Alternatively, the heights are such that a Simple cantilevered sheet pile wall could • be feaSible, but In this case care would need to be taken to ensure that the retained • fill could drain, to aVOid budding up an elevated water table For and on behalf of • COFFEY PARTNERS INTERNATIONAL PTY LTD • • • • DR N S MATTE'S • • • • • • • • • • • • • • • • As the client of a consulting geotechnical engineer you MOST GEOTECliNICAL FINDINGS ARE • should know that sl:e ~ubsurface conditions cause more PROFESSIONAL JUDGM!;:NTS construction problems than any other factor ASFElfhe Site exploration Identifies actual subsurface conditions • ASSOCla'lOn c' Englneenng Firms PractiCing In the only at those points where samples are taken The data GeosCiences offers the follOWing suggestions and were extrapolated by your geotef hmcal enf,'neer W'10 obser,atlons to help you manage your nsks then applied I'Jdgment to render an opinion about • overall subsurface conditions The actuallnterfcce A GEOTEC:1NICAL ENGINEERING REPORT IS BASED between matenals may be far more grad'lal or ablupt • ON A UNIQUE SET OF PROJECT-SPECIFIC FACTORS than your report Indlca,es Actua: conditions In areas Your geotechnICal englneenng reoort IS based on a not sampled mal differ from those predICted In your • subsurface explorat'op plan deSigned to consider a report Wh,:e nothing can be done to prevent such unique set of prolect-speClflc faclOrs These factors sltuatloPs you and your geotechnical engineer can 'hork typically Include the general nature of the structure together to help minimize their Impact Retaining vour • geotechnical engineer observe construction can be Involverl ItS size and configuration the location of the to structure on the site 0ther Improvement'; such as particularly beneficial In thiS respect • access roads parking fots and underground utilities and the additional nsk created by scope-of-servlce A REPORT'S RECOMMENDATIONS • limitations Imposed by the client To help avoid costly CAN ONLY BE PRELIMINARY problems ask your geotechnICal engineer to evaluate The construction recommendations Included In lour • how factors that change subsequent to the date of the geotechnical engineer s report are preliminary because report may affect the report S recommendatlon<; they must be based on the assumption that conditions • revealed through selective exploratory sampling are Unless your geotechnical engineer ,nd,cates otherwise indicative of actual conditions throughout a site do not use your geotechnical englneenng report Because actual subsurface conditions can be discerned • only dunng earth" ork you should retain your geo • when the nature of the proposed structure IS technical engineer to observe actual conditions and to • changed for example If an office bUilding will be finalize recommendations Only the geotechnical erected Instead of a parking garage or a refngerated englnee' who prepared the report IS fully familiar With • warehouse will be built Instead of an unrefngerated the background information needed to determine one whether or not the report S recommendations are valid • • when the Size elevation or configuration of the and whether or not the contractor IS abiding by appli proposed struc.ture IS altered cable recommendations The geotechnical en(;lneer who • wh~n the location or orientation of the proposed developed your report cannot assume responsibility or • structure I~ modified liability for the adequacy of the report s recommenda • when there IS a change of ownership or tions If another party IS retained to observe construction • • for application to an adlacent site GEOl ECHNICAL SERVICES ARE PERFORMED • Grotechmcal engineers cannot accept responsibility for FOR SPECIFIC PURPOSES Ai'llD PERSONS problems that may occur If they are not consulted after Consulting geotechnical engineer; prepare reports to • factors conSidered In their report s development have meet the speCific needs of speCific indiViduals A report changed prepared for a Civil engineer may not be adequate for a constru "boll' the potential for haz3rnous materials eXl3tlng at mates was not one of the sp.-'Clfic purposes for which It : the site The equipment techniques and personnel was prepared In othe, words while a contractor may used to pertorm a geoen~ironmental exploration differ gain Important kllowledge from a report prepared for substant'lily from those applied In geotechnICal another party the contractor would be well-adVised to engineering Contamination can create malor risks II diSCUSS the re[X)rt With your geotechnical engineer and you have no In:orrr'3tlor, about the potential for your to perform the additional or alternative worr that the jlte being contaminated you are advised to ~peak with contractor believes may be needed to obtain the data your geotechnical consultant for information relating to specifically appropriate for construCllon (ost estlmdtlng geoe,w,ronmental,ssues pl.rposes ) Some clients believe t,.,at It IS unwise or unnecessary to give contractors access to their geo A GEOTECHNICAL ENGINEERING REPORT IS technical engineering report, because .ney hold the SL,B)ECT TO MISINTERPRETATION mlstdken ImpreSSion that Simp'y dlscldlmlng responsI Costly problems can occur when other deSign profes bility lor the accuracy of subsurface Informat.on alwavs Sionals develop their plans based on misinterpretations IfIsulates them from attendant liability PrOViding the of a geote,hnlcal engineering repon To help aVOid best available information to contractors hf'lps prevent miSinterpretations retain your geotechnical engineer to costly construction problems It also helps reduce the work With Other prOled deSign prolesslonals who are adversarlal attitudes that can aggravate problems to affected by the geotechnical repon Have your geotech disproportionate scale nlCd ' engineer explain report Implications to deSign profeSSionals affected by them and then reView tho,e READ RESPONSIBILITY ClAUSES CLOSELY G~slgn prcfesslonals plans and speCifications to see Because geotechnical engineering IS based extenSively how they have Incorporated geotechnical fadors on ludgment and opinion It IS far less exact tha,., other Although tertaln ot'1er deSign profeSSionals may be fam deSign diSCiplines ThiS Situation has resulted In wholly iliar With geotechnical concerns none knows as much unwarranted claims being lodged against geotechnICal about them as a competent ~eotechnlcal engineer engineers To help prevent thiS problem geotechnical engineers have developed a number of clauses for use In BORING LOGS SHOULD NOT BE SEPARATED their contracts reports and other documents ResponSI FROM THE REPORT * bility clauses are not exculpatory clauses deSigned to Geotechnical engineers develop final boring logs based transfer geotechnical engineers liabilities to other upon their interpretation of the field logs lassembled by parties Instead they are definitive clauses that Identify site personnel I and laboratory evaluation of field where geotechnical engineers responslbllltlE'S begin and samples Geotechnical engineers customarily Include end Their use helps all parties Involved recognize their only final boring logs In their reports Final boring logs indiVidual responSibilities and take appropriate action should not under any CIrcumstances be redrawn for Some of these definitive clauses are likely to appear In inclUSion In archltedural or other deSign draWings your geotechnICal engineering report Read them because drafters may commit errors or omisSions In the closely Your geotechnical engineer will be pleased to transfer process Although photographiC reprodudlon give full and frank answers to any questions eliminates thiS problem It does nothing to minimize the POSSiblllt, of contractors misinterpreting the logs dUring RELY ON THE GEOTECHNICAL ENGINEER bid preparation When thiS occurs delays disputes and FOR ADDITIONAL ASSISTANCE unantiCipated costs are the all-too-frequent result Most ASFE-member consulting geotechnical engineer Ing firms are famll'ar with a variety of techniques and To 1I1lnirTIIZe the likelihood of boring log mlslnterpreta approaches that can be used to help rednce riSks for all (Ion give contractors ready access to the complete parties to a construction prolect from deSign through geotechnical engineering report prepared or authOrized construction Speak With your geotechnical engineer not for their use Ilf access IS prOVided only to the report only about geotechnical Issues but others as well to prepared for you you should adVise contractors of the learn about approaches that may be of genuine benefit report s limitations assuming that a contractor was not You may also Wish to obtain certain ASFE publications one of the speCifiC persons for whom the repert was Contact a member of ASFE of ASFE for a complimentary prepared and that developing construction cost estl- directory of ASFE publications * For further information on thiS aspect referellce should be made to "GUidelines for the • PrOVISion of Geotechnical Information In Construction Contracts" publIshed by the Institution • of Engineers Austlalla. National Headquarters. Canberra, 1987 THEASSOCIATION OF ENGINEERING FIRMS • A5FEPRACTICING IN THE GEOSCIENCES 8811 COLESVILLE ROADISUITE G 10000ILVER SPRING MD 20910 • TELEPHONE 3011565-2733 FACSIMILE 301/589-2017 Copyneht 19Q] by ASFE Inc Unless ASF'E grants specifIC permlSSlon to do so duplication ot thiS document by any means whatsoever IS expressly ploh,blted • Re use Qt the wordm& In thiS document In whole or 10 part also IS expressly prohibited and may be done only With the express permiSSion 01 ASFE or lor p"rposes 01 review or scholarly research • BPCO~Q2AIJ 5M • Repnnted WIth penmSSlOn by Coffey Partners internatIOnal Pty Ltd 1993 • • • • • View towards <:astern end of w ~JI , • showing erosion of • fill behind wall, back-toppling of • blocks in • foreground • • • • • • • • Photograph I • • Advanced deterioration , with • wall fully collapsed due to loss of • support from • retained fill • • • • • • • • • • Photograph 2 • • • • • • MINOR EROSION OF FILL • /... BACKFILLED BLOCK FILL -~~SHED OUT CENTRAL BlOCK • _____ FOOT BLOCK IN PLACE CD ~_.'~> • SEDIMENTS • • EROOfD FILL • • ~ 1PROGRESSIVELY BACK nLTING BlDCKS FILL ~ • ______BLOCK THRUST OOT ~OT • ® SEDIMENTS • • • • FILL -~~-APPROX MID WATER • ® SEDIMENTS • • FAILURE DETAILS • PUMPING • STATION • • • • • • • • PLAN • 1'2000 APPROX • Pty Ltd eoosultio9 Engineers in the geotechnical sciences Coffey Partners Internat " A .C.N 003 692 019 • drawing no. drawn BMD/SW PUBLIC WORKS DEPt.RTMENT • ------GLADESVIUE HOSPITAL SEA WALL COffEY 9986/1-1 scale (metres) DETAILS OF INVESTIGATION • job 00. • S9986/1 • • • • • • .,------~------• • • • • • • ., • • • • • • • • • .-.- " . • .' • .- '. ~ - ~';~t;:;~ ,- .. ~< ~"'.i"'1-"'_ ~ - L ~- ') • ~ • , " • '. • " • -- • • • Coffey P,ortners International Pty Ltd • ACI\I 003 692 019 COfFEY Explanation • descriptive t&rms Sheet 1 • soil and rock IBBI • • SOIL DESCRIP110NS ClaSSification of Mate"JI oased on UntfledClassdtcatlon System {refer SAA Site If''Ivestigation Code AS1726-197S "dd • No 1 Tabl!:: 011 • Mc:sture Condition based on ~p!learance of ~I)II dry looks Ilnd feels dry coh'~ 'Je sOils u:oually hard powdery or friable granular salls run freely through hands • mOist Sod feels cool darkened In colour cchest .... e sods usually weakened by mOlstl.ore granular sOils tend to cohere but one gets no free water on hands on remouldlnfJ • WC'tt Sod feels coot darkened In colour cohesive sods weakened granular SOliS tend to cohere free water collects on hands when remouldLng • Consistency based on unconhned compressive strength (Qu) (Qenerally estimated or meaSLI~ed by hand penetrometer) term • I very soft I soft I firm I stiff I very stiff! hard I Qu kPa l5 50 100 200 400 • If sod crumbles on test without meaningful result It IS described as friable DenSIty Index (generally estimated or baSE'd on penetrometer reSults) • term I very loose I loose I medium dense I dense I very dense I • densltv Index! 0 % 15 35 65 85 ROCK DESCR IPTIONS • Weathering based on visual assessment term criterIOn • Fresh Rock substance unaffected by wearhenng Slightly Wea,hered Rock substance affected by weathering to the extent that partial stalOing or partial • discolouratlon of the rock substance usually by limonite has taken place The colour and texture of the fresh rock IS recogntsable strength properties are essentially those of the fresh rock substance • Moderately WeatherPd Rock substance affected by weathen.,g to the extent that stamlng extends throughout whole of the rock substance and the anginal colour of the fresh rock IS no lor.ger recog • nlsable Highly Weathered hock substance affected by weathering to the extent that IImontte staining or bleaching affects the whole of the rock substance and signs of chemical or phYSical decomposition • of IOd ..... ldual mlOerals are usually eVident Porosity 3nd "trength may be Increased or decreased when compared to the fresh rock substance. usually as ,I result of the leachmg or depOSition of .ron The colour and strength of th~ orlgmal fresh rock substance IS • no longer recognisable Extremely Weathered Rock substance affected by weathenng to the extent that the rock e ... hlblts SOIl properties I e It can be remoulded and can be claSSified according 10 the Unified ClaSSification System, • but the texture of the original rock IS stili eVident Strength based on pOIOt load strength Index corrected to 50 mm dlamf'ter lsi 50) Irefpr I S R M ,Commission on Standardisation of Laboratory and Field Tests Sugge~ted MethodS for Determtnlng the Uniaxial Compressive Strength of Rock Matenals and the POint Load Strength Index Committee on Laboratory rosts Document No 1) 'Generally estimated x indicates test result) claSSIficatIon lextremely low I very IOw'-;,-JI';-_....::lo"V:.:,'-_-;;~um high I very hIgh I extremely hlslJ Is (50) MPa _ 003 01 03 3 10 The unconfined compreSSive strength IS tYPically about 20 x 'S50 but the multiplier may range, for different rock types from as low as 4 to as high as 30 Defect Spacing claSSification spacing m lextremely close I very close I close I medium I Wide I very Wide I extremely Wide I 003 01 03 3 10 Defect deSCription uses terms contatned on AS1726 table 02 to deSCribe nature of defect (fault JOlOt crushed zone clay seam (etc) and character (roughness extent coating etc) • • Coffey Partrors 1r.:ernallOnal Ply Ltd • ACN 003 692 019 COffEY ExplanatIon • graphic symbols Sheet :2 • soil and rock • • SOIL • :\sphaltlc Conuete or Hotr.1lx Gravelly C,ay (ll. CHI • Concrete Sandy Silt (M L) Topsoil Clayey Sand (SC) • Silty Sand (SM) • Peat Organic Clays and S,lis (Pt, OL. OH) Sand (SP. SW) • Clay (CL. CHI Clayey Gravel (GC) • Silt (ML. MH) Silty Gravel (GM) Sanely Clay (CL. CHI Gravel (GP. GW) • Silty Clay (CL. CHI • • • ROCK • Claystone (massIve) L,mestone Schist Siltstone (massive) Coal Gneiss • Shale (laminated) Dolente. Basalt QuartZite • Sandstone (undifferentIated) Tuff Talus • Sandstone. fine grained Porphyry Alluvium • Sandstone. coarse gramed Granite • Conglomerate Pegmatite • ~t------'------i .~ SE:AMS ~ Seam >0 1 m thick .t (on a scale 1 50) Seam 0 01 m to 0 ' m thick (on a ~cale 1 50) ·1.~_r------~ z INCLUSIONS (SpecIal purposes only) .rg ~ Rock Fragments Ironstone Gravel, Latente .if Swomp Shale Breccia In Sandstone .1 @t------~ • ~ Water Level .§ Surfaces Known Boundary ______Probable Boundary __ , --___ , Possible Boundary • • • Coffey Partners Internallonal Pty Ltd • AC N 003 69~ 0'9 COffEY sounding no .engineering log Tll sheet 1 01 1 .hand auger & dynamic penetrometer imlI S9986/1 • office af oj ph no chent PUb1.1C Works Department dale 10/9 /93 pn-c1oal • projSct Tarban Creek Seawall • location 4m lnslde seawall, upstream end field work by BMcD rJ.ot ho:~ diameter 100= hammer mass 9kg hamme· drop 510= RL sur:aC8 measured'd8tum • I c c matenal and structure - 9 0 Q ~~ blow (.ount Q)C <.I'D ;;; t: £ mo .... 0 C Cx u 0.0 soli type plasticity or panicle charactenstlc";, I ~ ~~ ~; blowsli • Ii depth ~ "E0"- colour secondary and minor components SOmm samoles '"~ " I ~ metres ~ 00 fissures roots, residual structure o C i u; (ij '"_ '" 0 ~ E 8 g ~ o c t 23 U - N 2 4 6 8 10 12 14 0" °1°...l._ ~I • :;, I I en <'"Tn S" ~ M n -' I 1 1 , ._1. I ~ --- • I 5" , 0 -J i '.In 3 3 3 ~ , .~ , • 158= --- 3 2 2 • MJ) 2 1 1 I VI, 1 Changes to grey colour I • 1 1 • 10 1 ~ 1 • = 1r approxlmat:e Dase or • seawall 1 1 Change to dark erey coloul • 1 • -.-- , 20-,-- 3 2 2 SC rT.AVFV ~ANn' finp graln_ed MD • rl"rk orpv hi oh 1 2 1 nl"cr;C'-Ir" C'l"" r .... "C'P "f 2 1 1 • "h"ll F. ",,,,,rl fY~n '0"1",, , C'''~nno ~nrr;n<> c~pl 1 lIT 1 AT T Tn;~TTM • I 1 I ? 7~ "rnnnpn hnlp hpC'""cp • 1 - ""np~ ,r" 0"""', ·0, -' I 1 , 30 ... .n~ • 1 , • 1 1 f-- f.. • I I 1 I' , , • r ! J -- I- 1 • J 40 I I penetrometer c'-lncatlon COl ...... oc:tM! I!Ity IndP ~I'e!!!! !!!1!!! ...... !I~ • uncMI~ sample 50mm VS "1!" '*""< U50 - __m En10m."... I!!!!!508mm_ pe"ebattoli 2 3 ~~~ S '""~n "'" • F ,~ ) 0 dlslurbed-- e.emp6e SI ".. ~~ VSi .." om • m-"~ H ..... ) ~ !!!!!! -0--"" Fb b_ """ 600mm_ 10 J&/'I 86 _ ...... on cse. shown M _. Vl -. >0000 • Y W l ""'- ~ MO ~ 0 ) 4~ 305mm drop - • -H>I 1 J • orhce and JOb no S9986/1 chent Publ~c Works Department dale 10-9-93 • pnnolJrl pw)I>Ct Tarban Creek Seawal] klcatlOn downstream of plJmp~ng stat~on field work by EMcD • ------.. hole diameter hammer ma~s hammer Clrop c 0 c matenal and structure I x 0 0 >-~ blow count -' o _ 9 c u" ~ Cc • ~ U soil type plmlclty or pa··tlcle characteristics I g " m fi:3 ~ - ~ E' i3 0 0 0 depth ~ "E colour secondary and minor components blows/1 SOmm :!l a~ samplas ~>- c "0z- metres ~ ww 0 "' "' "' 0 ~ fissures roots residual structure u g~ )'j c "E 1 23 "N 14 • U u~ '" 2 • 6 8 10 12 WI -- I ~ .SAND· f~na_to coarse M VD 2 2 2 pr:'linprl dar k J?r.eY- some 1 .. .raol:.-...£i.b.r.e.a --ton. 3 2 2 ~ , 'l1ll1mm- Mn1 1 1 ---"I.LL • 1 1 1 J - 1------, -r-GW SANDY GRAVEL: Sandstone - 1 1 2 • 4 >1~ blocks., FlU • 10 , ~...a.t:..t..e=1...mad.e.....tQ • - • - • I • 30 I • -- • . • - - -- - , - r- • I 40 L COi ___ penetrometer • ,.,.. a.np"'IInd_ ~llo.. .,1'I"Ibc* IC)!I6eMI!y IndeII C~ng U;O ~1.Ift«I ..~5Omm .nd toll $_,""""'. w" ,.,. Enttm Statu perwtmion I 2 , ..... ~ ...... '"S ... ."..., 508mm "'" F • 0 ...... - SI '"".~ VSI ~ D&:l~ m_~ .... -- H ..... ~ ".,., 0--"" Fb .- BDkg 600mm drop • y 1OJa/'l86_ .... oodm~ U Vl w """" l ...... uo - - 0 ""'~4.521<0 305mm dl"OQ VO -,_. • ~ --- -- • --- - • • _COffey Partner':.. International Pty lid AC N 003692019 COfFEY I sound -'I. no ·engineering log I IC3 ~Of 1 ·hand auger & dynamic penetrometer DmJ • office and JOb no S9':186/1 chent· PublJ.c Works Department dale 10-9-93 • pnnClpal p!O)I>et Tarban Creek Seawall location 4m l.nsl.de seawall. NE Facing sectl.<:n hale work by BMcD •I-~ - - • hole dIameter nammer mass hammer drop RL surface datum c - - x -- 0 I matenal and structure Q g_ >- • 1 10 1 • 1"11 1 W • 1 -- • MD 1 Aooroxl.ma te base of L ._-- 1 • "pm"" 11 ., VT 1 3 3 c:r CLAYEY SAND: fl.ne. dark 1 of shells & ..l, 20 "rev trace c-1 ve»etation clav hi»h 1 • nl""r""1rv AT.T .TTVTlTM 1 - • 1 • 1 1 • 1 Auger pulll.ng down , 1 30 stron"lv c0uld not I • MD ._-1- ,..nnrrnl ' ' , _.- - 2 2 1 • VL 1 I I • 1 - ---1 • , 1 i - • 1 I 40 i , _ond ..... COl ...... Indo • penetrometer "".. c;:a...tnc.Don !r:1T'It:Ioa "e6wi ttl c~ undoc..wd ..amPe 50mm __,nd d dot..:ripOorjm vs W"I "'" U'O ~O'I ;;;;&Id S ~ , , , .....- ...... F - 0 s, "',"'" • W.!-~ .-. "'""""- «mz.r.retu..r VSI ...-... H -'"'" -""""'- 0--", F. ~.... 600mm_ '!!!!! .""'"..- 10Ja/l86_ ...... ono.r:e~ ~. VL Y "w L .....-,- • "0 fIk:!:!!1R!!!~ - 0 "..sao 305mm "roo ..... • - "x;alton 4m ~ns~de seaHal!, down stream end flSId NOrte: by BMcD • >-~ - - • hole diameter hammer mass hammer drop R L surlace datum ~_-2 -.,...... ,---r-- --,--;-;:----:---==;::;;::-..;;::;:::---..,.-r-!>-~,,~-.--- • ~ c malonal and structure ... , Q Q blow count ~ g ~ ~ ~ sOIl typo plastiCity or particle charactenstlCS ~ Q I ~ ~ J ~ §: ~ sampl,'Is depth ~ ~ E colour secondary and minor components ~ iSJ iii;' ~ ~ ~ hlows/lSOmm • CI. .... metres ~ ~ ~ fissures roots residua! stnJcture ~ g ~ ~ "U "0 1 2 3 C. ~ 0 0 f5 iii ~ ~ 2 4 6 8 10 12 14 .~~.==~=*'~~~~==~~==~~U~~~~~rrnTrrrR SAND- ~~+-+---~--__ +-~~~~~~~~~~~~~~~~+-ll~SW "~ne grained some M vn ~? .slit root f~bre", "'''1>''''TT r.l <;AND - -{~ne to coarse 'J 2 It hrnwn Orf'V dark I!rev some shells & • H-t-t++-+------+--+-j- ' VP oP r-" t 1 on ALT • • ~~~--~--+-r--+------~-+~-+~#H~~+HH++Hrl ~ ~~~=l=====l=====t==t====tL~~~m~~~t=oQIf~a~u~gle~r~c~o~n~t~r~o~I====j===j===j-~-+~+tt+i1-tt+i1-tt+i1~ ~ H-H-+-t-+--..~- 3 0 -'I---+__ +,u,,-u=t-=t-=in=-l=.g_d=-o=-wn=:...:i:::n;:.t=-o=--.=sc:oc:i:::l=-_-t __ t-_+---+-+_+t1H--HH-+-H-+-H-' +-t-t-H ~~q=~~r~~======~~~~~ttrr~ I .HTTr~,·----r---:'--+--~------~-~~-+-+1*~HH~++ I - I I .mn~,~t=~~======j=~~~~~:! I l i I I I .~======~4=O~======r======~====~~~~~~~==~u penetrometer note. .-npIM 8nd ,.., eon.lst. pM ttl IncSa u~o ~~ ump6e SOmm VS w" "'" J -.- 5 ~. F .... 51 • --om"'" ""H ....., ~ ...... i' " "l ""- •r_::-:------1 MO ----...- -3 • .5.2Iq;j 30Smm drop 0 --- YO ...,- • -- -- • • • • COlley Par,~e'5 ,nlernal'on", Ply Lta ACN 003 &970''1 • COFFEY so... .nd,ng no • engineering log TC4 s.hoot '" ] • hand auger & dynamIC penetrometer '»HI S99b6/l 1--- otflce and ,00 no ----- PulllC ...... orks Deparlnenl 10-9-93 • I ctlent nate I r""Clpal Tarb~~ Creek Seawall • I poo,ec1 BHcD Ioc>""n 4m l~slde sea ...... all, down stream end ------• hole dIameter "~mmef mass hammer drop A l s""r1ace oarum ~_.,T--~-.__r-_r---=_~~-~--_r-.__.------c: malenat and struaure I >-0; !. 1 o boo>oo count • j,e , I 9 ~ :g !>Col type otashcrry 01' partICle charaCl6nshcs :: g ~ ~ f-r-: [.--,,-1------I ~ s.amplf''Io OE!plt'I ~ ;, ~ cotour secondar., and mmo components II ~ ~ ! ~ ~ ; ~ i b~.J15Omm • , J, mel as. 0. ~ .,. Iossu'es roots reSidual S1rvc1ure E e 3~ ;, H • ~l 2 .. 6 8 10 12 14 ~~~~==~~~======1 _1_~_~~_--5AND hue HalOed. some ~~I-'lDt 3 3 I I_I 1 I s • f+trl-H------4--l-~-3L~~JJbJQQJ fJbre JOPSO~--! - - I I-! J _ 1_ _ __ SAND flue to co~__ -j 2 2 1 __ -- II -i-- ~------_bEam gr~? • some fh'"~" _. -!= "-'I ' '1- - '-'- - -- • ---,- ,---- -graye) =,anasroneeuuUlg 1--' HD; I I ' ' II - --'--1-- -- HI_l 1--- '-D I --r-1- l • ff------'--'--1-- - -- 1-, I 3 I I • -'----t---~~1--' -=--~ -- Jj==~-~:_I;~~ -t-:- -: -II, ,~~ -~-10 +~i -- 1=--- -,=--::-;=!-il- f --- -- 1 • ~ l-w ,----1 1------T-r-1-T-1 -- - - 1-- --I --f-- -r i - -I f-'-1rH+--f- h L __ ~ ___ L -- • - u - u-,_==_ n,_~C _~YEY SAND hoe grawed:1-::-~ MDJ-f-.l ~L uW - - J ---j--l--t-- rfi~~eI,SaudstoUegravel l-- - I-~\~~\- - I -_--_---, I'! • H-l++-+_- -~~_-__ I- __ -1- -til SANDY CLAY med1um i- -~-=-~ ~_~ _~ 11_ I H-t-t+-t-t--]~--~-=- plast1oty, black, root f -1=-- : 2 1,1 • ______20l--!- f1bres • wood ,_ .-=---:;-t--j --- HcH-l-f---1----- _ 1__ __ (-lAYEr SAND hue gra.u~ __ ,_'0- ~~ __ 1 f+t+t-+-f - --~- -1--- da~y some shells 1.--1- :- I II i 1 • --j --1--+ - --"e.geLa.llOn AJ J IIVIJ[H =J--' '1 -- I - -- -i ' • ,-~I--=j=J-l------{::::-j-:::- -i~i~~r L - - \- • -+ ---1-- -+ -- '::1::: --;-l+[, \- -- 1 , H-tl-h-t-__-l_:-:: __ ~ J~-= :~~ l1mH of auger control - -l---;-::- -~ ~I - -- -' - 0 putt1ng dol"ffi lntO SOlI I I • ':; f+t+H--j- - 30 ,------\-- 1- I t H-t-t++--t----r-~------j-- -, I ;! z • 0 ------~ z ~ ------• :': ~ '"~ • wz __ _=__=__=__=_::_-=--=--=--_-_-_-_-__ -__ -- Ii ~tt::~:f-~:t--1---ti---=-=--~=·~~:4="o=--1:=---~tl':::----~~~------ri"' i F~_- ---~ • ·> ~:~==~~~d===~======~~~~~~~~~tiJ~-~~ w • penetrometer C_":y_ ",0 .... ~ '~~ ... " (; ~,,.-,---~ -0-~. u ~") ~ -~1-.;;-n--':';::';~ D -~ , --o. I ::/.£L-~- ~ ~O' • " _ ...... I ,-~ - 0 _. "., .-- ~ " ~- > " • ~ - ., ~ • , -~-- [;; 8 --~- • ~ "" • • • • • • • • • • • • • • • • • • • • • • • • • • • •