Civil Engineering May 2022 | Vol 30 No 4

Civil Engineering May 2022 25 fit into the available space between the concrete encased sewer and the erf front boundary. The scour protection mattresses for the failed walls protruded onto the beach area beyond the erf boundary in accordance with previous agreements with local authorities, but this encroachment was no longer permitted for the new walls. DESIGN SOLUTIONS Jet probing was done to determine the bedrock levels and sand thicknesses above bedrock along the length of the walls. Beach sand was overlaying bedrock which varied in level from 1.2 m below MSL at the north end of the site to 2.1 m below MSL at the south end. The exposed bedrock on the beach immediately north of Erf 234 was identified as a metasedimentary hornfels rock, and being quite brittle. To prevent future scouring of the founding material of the new wall, and making the wall stability independent of the scouring in front of the wall, it was decided to construct a mass concrete SANDLEVELVARIES LEVELAPPROX. 0mMSL (SEPT2017) +4.10mMSL MLWS = -0.66mMSL MHWS =+0.84mMSL HAT =+1.12mMSL +0.48mMSL APPROX. +3.05mMSL R460 SECTION 1-1 SCALE 1:25 SAND SAND SEA +3.69mMSL +2.80mMSL 3000 450 1980 1360 810 APPROX. 230 450 350 3600ATSOUTHEND (VARIESNORTHWARDSALONGWALL) APPROX. 2210 ~460 1190 710 2460 125 125 75 550 137.5 250 800 300 40MPaMASSCONCRETE TOBEDROCK 75 150 5 5 1400 UNEVENANDROUGH EXISTINGBEDROCK APPROX. -1.7mMSL 340 340 APPROX.+1.35mMSL +0.89mMSL SAND PROPERTYERFBOUNDARY OLDEXISTINGRETAINING WALLTOREMAIN CONCRETEBULLNOSE/RECURVE EXISTINGCITYOFCAPE TOWN220Ø (ID)GRAVITY FOULSEWERPIPEENCASED IN1800 x500mm CONCRETE (INVERT LEVELVARIES) 75ØWEEPHOLE FILLEDWITHNO FINESCONCRETE (FREE DRAINAGEWITH 30%POROSITY) CONSTRUCTION JOINT (CJ) CAST INSITU 40MPA /19mm REINFORCEDCONCRETE CANTILEVERWALL STEELSHEETPILECOFFERDAM PERMANENTSHUTTERING 120mmTHICKCONCRETESLABWITH MESHREINFORCEMENTREFNo.395 SCABBLECONCRETE SURFACEFOREXPOSEDAGGREGATEFINISH EXISTINGSTOEP STRIPFOOTING EXISTINGBASEMENTWALL &STRIPFOOTING PERFORATEDSUBSURFACE DRAIN 100mmØWRAPPED IN 25mmSTONESURROUND Y32 INBEDROCK EDGINGPRECASTKERBE1 LOCALIZEDUNDERMININGTOBEFILLED WITH 20MPaMASSGROUT APPROX 830 350 75ØWEEPHOLE@ 2.1mC/CSPACING WITHNO FINESCONCRETE SAND C.J 120 250 50mmBLINDING 50mmBLINDING +1.9mMSL 200 30 +3.31mMSL 1000 DRILLANDGROUT (USING Fcu=40MPa@ 28DAYS -SIKAGROUT 212ORSIMILAR) Y32 350mm INTOBEDROCKAT 800mmSPACINGS. (27No.) HOLEDIAMETER=80mm 950 1650 SHEETPILESTRIMMED TOTHISLEVEL APPROX.500 350 350 150 1200 GEOTEXTILEATWEEPHOLE DRILL&GROUT ANCHORBARY20 100 100 3350 (TONEWWALLFACE) 1300 FINDRAINKAYTECHFLODRAIN 200 VARIES 250MIN +0.48mMSL +0.93mMSL TOPOF CONCRETE BASE +0.93mMSL +2.13mMSL +0.93mMSL 1 1 FRONT ELEVATION (FOUL SEWER PIPE NOT SHOWN FOR CLARITY) SCALE 1:50 NORTHWALLCORNER CORNER APPROX.1750 5400 205 250 500 500 500 500 210 BEDROCK LEVELAPPROX. -1.7mMSL SAND LEVEL (VARIABLE) 360 EXISTING NEIGHBOURING WALL SHEETPILES CONCRETESTEPS CONSTRUCTION JOINT R20BARS -SEEWALL JOINTDETAIL EXISTING DRAINAGE CHANNEL 170 5400 5400 5400 5400 5290 2190 360 540 540 JOINT 540 540 540 540 JOINT 540 540 540 540 JOINT 540 540 540 540 JOINT 540 540 540 540 JOINT 540 540 540 CORNER 540 540 540 540 570 VARYINGTOPEDGEOFSHEETPILE NOT INDICATEDFORSIMPLICITY 1300 WALL JOINT PLAN DETAIL SCALE 1:10 400 300 300 SCABBLECONCRETE SURFACEFOREXPOSED AGGREGATEFINISHOR USERETARDERON SHUTTERS R20GALVANIZED 600mm LONGBAR (Fy=250MPa) DEBONDINGDENSOTAPE ORSIKABLACKSEAL LASTICWITHFABRIC VOIDFORMER JOINTEX ORSIMILARAPPROVED 20 2500 2500 VERTICALSTRAIGHT JOINT EDGEONEXPOSEDSIDE SEASIDE 340 400 TYP. SECTION PLAN 5-5 SCALE 1:25 450 SAND VARIES Ø220 (ID) 340 1640 Y32DRILLED INTOBEDROCK SHEETPILING VERTICAL OUTERFACE EXISTINGFOULSEWER PIPEENCASED IN CONCRETE CAST INSITU 40MPA/19 REINFORCEDCONCRETEWALL 400 TYP. APPROX 1000 EDGEOFEXISTING CONCRETEENCASEMENT OFSEWERPIPE 800 TYP. 30 800 TYPICAL DRILLANDGROUTY32 INTOBEDROCK 350 FILL 20MPaMASSCONCRETE INVOIDBETWEENSHEET PILEANDEXISTING CONCRETEENCASEDSEWER 800 TYPICAL 200 200 CADFILENAME:P:\23997 -HartwigHouseWall\33CM\02-CADD\03-AsBuilt\02-Drawings\Drawings\K2000RevZ.dwg NOTES: 1. ALLDIMENSIONSARE INmmUNLESSOTHERWISESPECIFIED. 2. LEVELS TOMEANSEA LEVELS (MSL)DATUM. 3. DIMENSIONSAND LEVELSOFEXISTINGWALLANDSCOUR APRONTOBECONFIRMEDBYCONTRACTORONSITE. 4. BEDROCK LEVELS INFERREDFROM JETPROBINGBY WELLCORE INOCTOBER2017. 5. SAND LEVELS FROMSURVEY INNOVEMBER2017 6. CONCRETETOSPECIFICATIONPSG REFERENCEDRAWINGS: K1002 K2001 K2003 K2004 7. CONCRETEEDGESSHALLHAVEA25x25mmCHAMFER. DRAWINGSTATUS: CLIENT: ARCHITECT: TITLE: SCALE@A1: CHECKED: APPROVED: DRAWN: DATE: PROJECTNo: DRAWINGNo: REV: PROJECT: DESIGN: F.DEROUBAIX A.VANTONDER L.KILIAN 2019/02/20 F.DEROUBAIX THEHARTWIGTRUST - REPLACEMENTOFSEAWALLERF234, BLOUBERGSTRAND WESTWALLELEVATIONANDSECTION 23997 K2000 Z REV DATE BY DESCRIPTION CHK APD 1:100 COPYRIGHTRESERVED C The content of this document is privileged and confidential andmay not be disclosedor reproduced without the express authorisation of the author, being "WSPGROUPAFRICA (PTY)LTD" If drawing status= construction, a signed copy of thisdrawing (either inhardcopyor electronic format) is available at the officeof origin andat the office of issue. AS-BUILT PRNo.: TEMPLATEVERSION1.1 P.O.Box 413,Stellenbosch, 7599,SouthAfrica Tel: +27(0)21-883-9260Fax: +27(0)21-883-3212 www.wsp.com WSPGroupAfrica (Pty)Ltd Coastal andPortEngineering 980530 0 14-03-2018 LK ISSUEDFORCONSTRUCTION FDR AVT 1 29-03-2018 LK FOOTINGWIDTHREVISED,WALLLENGTH FDR AVT REDUCED, INTAKEWELLDIASIZEREDUCED 2 06-04-2018 LK BOUNDARYAMENDED,DIMENSIONSCHANGED FDR AVT SECTIONSAMENDED 3 18-04-2018 LK SECTIONAMENDED,SEECLOUDING FDR AVT 4 25-04-2018 LK ASPERCLOUDING FDR AVT Z 25-02-2019 LK ASBUILT FDR AVT Digitally signed byDeRoubaix, Francois DN: cn=DeRoubaix,Francois, ou=Stellenbosch (SteinHse), email=Francois.DeRoubaix@wsp.com Date: 2019.02.26 17:44:47+02'00' DeRoubaix, Francois Figure 9 Design solution of mass concrete foundation onto bedrock with cantilever concrete wall at Erf 234 Powerful Interface User-defined Beam Creep and Shrinkage Reinforcement Design Polka Engineering Software (Pty) Ltd Cell: (083) 675 5666 Email: coombes@polka.co.za