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TABLE OF FIGURES Figure 1.1 Study area location plan. Segment of the NATMAP 1:1,000,000 International Map of the World, Sheet, showing the east coast of , Newcastle to Nowra area, including . Inset Map of Australia showing Study area...... 1-2 Figure 1.2 The Wollongong City Council Local Government Area. The general Study area is the escarpment slopes north of Wollongong. The 1:4000 Map area considered during this research project is shaded in grey. The Subject area, defined for a spatial analysis carried out during this research project is highlighted with a red border...... 1-3 Figure 1.3 Wollongong City Council 1:4000 map sheet index map. Map area for this research project is bordered by heavy black line. Table 1.1 relates these map names to co-linear Central Mapping Authority 1:4000 scale map names...... 1-9 Figure 2.1. Proposed Risk Management Process, an overview...... 2-19 Figure 2.2. Risk for selected engineering projects, Whitman (1984). Note slope stability at 10-2...... 2-20 Figure 2.3. Detailed view of the proposed Risk Management Process showing use of maps, spreadsheets and databases...... 2-23 Figure 2.4. Conceptual representation of the decrease of a slopes Factor of Safety with time (Popescu, 1996, after Terzaghi, 1950)...... 2-25 Figure 2.5. A classification system for landslide causal factors. For example, preparatory causes 1.4, triggering cause 3.1 (Popescu 1996, adopted by WP/WLI)...... 2-27 Figure 2.6. Definition of terrain units at different scales. With larger map scale contours are more accurate, and more land units are recognisable; (a) 1:25000 scale, (b) 1:5000 scale (after Shih- Chia Chang, 1992)...... 2-28 Figure 2.7. Anbalagan and Singh (1996), general procedure for risk assessment mapping developed in the Himalayas...... 2-37 Figure 2.8. Sukhidang area, Kumaun Himalaya, India. Hazard and Risk are assessed on the basis of factor maps, which are not shown. The slope facet map delineates the areas upon which assessments are based, Anbalagan and Singh (1996)...... 2-38 Figure 2.9. Damage potential tables and associated risk assessment matrices, Anbalagan and Singh (1996)...... 2-39 Figure 2.10. Landslide management strategy for the Undercliff, Isle of Wight, England. Strategy aims to reduce and limit the likelihood of future movement by adopting four approaches (South Wight Borough Council, 1995)...... 2-42 Figure 2.11. Railway Geotechnical Services, Railway Services Authority of New South Wales, Australia, Geotechnical Risk Assessment matrix, with definitions of terms and example assessments (Railway Geotechnical Services, 1995)...... 2-47 Figure 2.12 Simplified version of Fells flow chart probability procedure...... 2-55 Figure 3.1. Rainfall contours for the ; (a) Maximum annual rainfall, period unknown (Young 1976), (b) Annual average rainfall 1931-1960 (Young 1976), (c) Average annual rainfall Bureau of Meteorology records (Ghobadi 1994)...... 3-3 Figure 3.2. Dana’s Geological Map of the District of the Illawarra dated 1848 (Viola and Margolis, 1985) Yellow represents the ‘Sydney Sandstone Formation’, Purple the ‘Coal Formation’, Red the ‘Wollongong Sandstone Formation’ and brown is ‘Basalt’...... 3-5 Figure 3.3. Regional Structural Geology of the study area (Herbert and Helby, 1980). (a) Extent of Permian sedimentation over eastern Australia; (b) Sydney-Gunnedah-Bowen Basin within New South Wales; (c) Structural subdivisions within the Sydney Basin...... 3-7 Figure 3.4. A generalised stratigraphic column of the Illawarra Region (after Bowman 1974)...... 3-11 Figure 3.5 Portion of Bowmans original scale 1:6336 Geology maps. Scarborough Sheet. Only spatial reference is limited cadastre of main roads and the coastline...... 3-26

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Figure 3.6 Portion of Bowmans original scale 1:6336 Land Stability maps. Scarborough Sheet. The top of the escarpment crosses the upper left side of this segment, and Buttenshaw Drive diagonally crosses the page...... 3-27 Figure 3.7 Portion of Bowmans Geology maps enlarged and superimposed onto a 1:4000 scale orthophotograph map of the Balgownie area. A clear lack of correlation between the geology and contour lines is visible...... 3-29 Figure 3.8. Locality diagram of the Seafoam Avenue/Thirroul Public School Landslide, Adamson 1962...... 3-31 Figure 3.9. Shellshear (1890) discussed the treatment of slip land near the cliff edge on the Illawarra railway line at chainage 33 miles (now, approx 53.8km) south of Sydney; a) Location plan showing position of railway, road and subsurface drainage lines. Position of railway and road is now reversed, b) Cross sections of drainage trenches/drives 3 and 4...... 3-41 Figure 4.1. Example Borehole Data Sheet for borehole C0013, one of the 154 boreholes in the BOREHOLE database and the GIS based GEOWELLS ‘overlay’...... 4-6 Figure 4.2. GIS generated summary plan showing distribution of boreholes in BOREHOLE database and location of the major faults included in the ‘FAULTS’ overlay...... 4-7 Figure 4.3. Computer model of geology within area of ‘clipped contours’, bounded by boreholes in BOREHOLE database. Stratigraphic surface generated for the Base of the Wongawilli Seam. Surface examined by cross sections at 500m spacing, orientated approximately perpendicular to the escarpment. North is vertical, and the map is at a scale of 1:50,000. is situated within the area of closed contours on the right hand side of the map...... 4-12 Figure 4.4. Cross section WongC8 (fifth from the left hand side of Figure 4.3) of the computer model of the base of the Wongawilli Coal Seam. The interpolated intersection point with the face of the escarpment is digitised and plotted in plan, as shown by the blue crosses in Figure 4.3...... 4-13 Figure 5.1. 1:4000 scale E12 map segments from northeastern Stanwell Park. Irregular, non symmetrical contours within two sites of land instability. Sites 001 and 002; (a) Topographic base map with cadastre and ‘GEOWELLS’ borehole location overlay, (b) Geotechnical Landscape Map series...... 5-6 Figure 5.2. Site 128. a) Segment of Geotechnical Landscape Map J9 including Site 128, and b) Pitsis (1992) 1:25000 scale Sheet 3 “Guide to Land Instability Stanwell Park to Wollongong” map segment showing, amongst others, Site 128...... 5-7 Figure 5.3. The Microsoft Access v2.0 database window, with ‘Tables’ selected. This is the first window to open when the Land Instability Database file is opened. This window shows the four Tables that are available within the Land Instability Database file. Also accessible through this window in Microsoft Access v2.0 are lists of the Queries, and Forms available within the Land Instability Database file...... 5-12 Figure 5.4. Example Record/Site Data Form (SITEDATA) for the Land Instability Database...... 5-13 Figure 5.5. The database window, Queries selected, in Microsoft Access v2.0. This window shows the Queries that are available within the Land Instability Database file...... 5-14 Figure 6.1. Map Legend, Geotechnical Landscape Map Series, Version 2.1...... 6-4 Figure 7.1. Histogram of Landslide Volume class (Fell, 1994), defined in Table 2.4. All 328 sites within the Land Instability database. Note GIS plan area and approximate depth used to determine volume...... 7-4 Figure 7.2 Areas of geological subcrop within the subject area. Nomenclature of individual geological features is as discussed in Chapter 3. Qta denotes areas of quaternary alluvium and Fault denotes the area of a 100m wide shear zone within the boundary of map G11...... 7-4 Figure 7.3. Geotechnical Landscape Map E12 Geology and Landslide spatial summary ...... 7-5 Figure 7.4. Geotechnical Landscape Map G11 Geology and Landslide spatial summary...... 7-6 Figure 7.5. Geotechnical Landscape Map L8 Geology and Landslide spatial summary...... 7-6

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Figure 7.6. Stacked histogram showing total subject area by area of stratigraphic feature and area of each stratigraphic feature affected by land instability...... 7-8 Figure 7.7. Composite stacked histogram and line graph, showing; as vertical bars, total subject area by percentage of stratigraphic feature and percentage of stratigraphic feature affected by land instability scaled on the left hand side axis, and on the line graph slip affected area as percentage of the whole subject area, scaled on the right hand side axis...... 7-8 Figure 7.8. Summary of WP/WLI (1993) landslide velocity classes for all the landslide sites, with data in this field (178 out of 328), in land instability database...... 7-11 Figure 7.9. Annual landslide occurrence/recurrence, assessed from the Land Instability Database...... 7-13 Figure 8.1. Wollongong University and daily and daily rolling periods (7, 30, 60, 90 and 120 day) of antecedent rainfall curves for the 20 year period, 1/1/1977 to 31/12/1996...... 8-5 Figure 8.2. Antecedent Rainfall Percentage Exceedance with Time. Based on the 20 year, 1/1/1977 to 31/12/1996 composite rainfall record of the Wollongong University and Bulli Pass rainfall stations...... 8-7 Figure 8.3. Segments of the Geotechnical Landscape Maps E12 and F12, showing Site 26...... 8-15 Figure 8.4. Site 26 Land Instability database Site Data Record form...... 8-16 Figure 8.5. Site 26, RSA Project 464 at Coalcliff, chainage 58.600km. Inclinometer A Axis Profiles for Borehole 2...... 8-17 Figure 8.6. Site 26, RSA Project 464 at Coalcliff, chainage 58.600km. Inclinometer A Axis Profiles for Borehole 4...... 8-18 Figure 8.7. Site 26, RSA Project 464 at Coalcliff, chainage 58.600km. Inclinometer A Axis Profiles for Borehole 6...... 8-19 Figure 8.8. Site 26, RSA Project 464 at Coalcliff, chainage 58.600km. Inclinometer cumulative shear displacement, rate of shear per day and antecedent rainfall curves...... 8-22 Figure 8.9. Site 26, ARPET Curves with significant antecedent rainfall values related to shear displacement...... 8-23 Figure 8.10. Segment of Geotechnical Landscape Map H10 showing Site 80...... 8-25 Figure 8.11. Site 80 Land Instability database Site Data Record form...... 8-26 Figure 8.12. Site 80. RSA Project 1559, Inclinometer 12 cumulative shear displacement, rate of shear and daily and antecedent rainfall, 1988 to 1989...... 8-27 Figure 8.13. Segment of Geotechnical Landscape Map L8 showing Sites 140, 141 and 142...... 8-30 Figure 8.14. Segment of Geotechnical Landscape Map M8 showing Site 143...... 8-31 Figure 8.15. Site 140, Land Instability database Site Data Record form...... 8-32 Figure 8.16. Site 140, RTA Project G1860 Inclinometer I60 profiles...... 8-33 Figure 8.17. Site 140, RTA Project G1860 Inclinometer I1000 profiles...... 8-33 Figure 8.18. Mount Ousley Road, all sites (Sites 140, 141, 142 and 143) composite plot. Inclinometer cumulative shear displacement, rate of shear per day, daily rainfall and antecedent rainfall curves...... 8-34 Figure 8.19. Site 141, Land Instability database Site Data Record form...... 8-38 Figure 8.20a. Site 141, RTA Project G1766 Borehole Inclinometer 1 profiles...... 8-39 Figure 8.20b. Site 141, RTA Project G1766 Borehole Inclinometer 2 profiles...... 8-39 Figure 8.20c. Site 141, RTA Project G1766 Borehole Inclinometer 3 profiles...... 8-40 Figure 8.20d. Site 141, RTA Project G1766 Borehole Inclinometer 4 profiles...... 8-40 Figure 8.20e. Site 141, RTA Project G1766 Borehole Inclinometer 6 profiles...... 8-41 Figure 8.21. Site 142, Land Instability database Site Data Record form...... 8-44 3 11/06/2008, Table of Figures

Figure 8.22. Site 142, RTA Project G1767 Profiles of borehole inclinometers 101 and 102 recorded on 29th March 1989...... 8-46 Figure 8.23. Site 143, Land Instability database Site Data Record form...... 8-49 Figure 8.24. Site 143, RTA Project G1778 Profile of borehole inclinometer 103 recorded on 29th March 1989 (original RTA profiles reproduced with permission)...... 8-50 Figure 8.25. Segment of Geotechnical Landscape Map M8 showing Site 145...... 8-52 Figure 8.26. Site 145 Land Instability database Site Data Record form...... 8-53 Figure 8.27. Site 145, Some inclinometer monitoring displacement vector profiles recorded by Coffey Partners International and Wollongong University...... 8-55 Figure 8.28. Site 145, Inclinometer cumulative shear displacement and rate of shear, daily and antecedent rainfall curves...... 8-57 Figure 8.29. Site 145, ARPET Curves with antecedent rainfall values related to shear displacement. Line X-X’ represents a threshold line, above which landslide movement can be expected to accelerate. At this site, the writer considers that A90 and A120 periods and magnitudes of antecedent rainfall show the best correlation with periods of accelerating, high and peak rates of landslide displacement...... 8-59 Figure 8.30. ARPET Curves with selected antecedent rainfall values related to an inclinometer indicated increase, high and or peak rate of landslide shear movement...... 8-61 Figure 9.1. Segment of the Geotechnical Landscape Map G11, including Sites 63, 64 and 65. Figure 6.1 contains the legend information...... 9-3 Figure 9.2. Site 63 Land Instability database Site Data Record form...... 9-8 Figure 9.3. Site 64 Land Instability database Site Data Record form...... 9-9 Figure 9.4. Site 65 Land Instability database Site Data Record form...... 9-10 Figure 9.5. Site 64, RSA Project 1569 at Scarborough, chainage 63.650km. Inclinometer A Axis Profiles for Borehole 3...... 9-18 Figure 9.6. Site 64, RSA Project 1569 at Scarborough, chainage 63.650km. Inclinometer A Axis Profiles for Borehole 7...... 9-19 Figure 9.7. Site 64, RSA Project 1569 at Scarborough, chainage 63.650km. Inclinometer Monitoring cumulative shear displacement, rate of shear, stand pipe and vibrating wire piezometric levels, antecedent rainfall curves and daily rainfall for the period 1988 to 1996...... 9-21 Figure 9.8. Site 64, RSA Project 1569 at Scarborough, chainage 63.650km. Inclinometer monitoring cumulative shear displacement, rate of shear antecedent rainfall curves and daily rainfall, 1989 to 1993...... 9-23 Figure 9.9. Site 65, RTA landslide near the intersection of Drive and Fifth Avenue, Project G1782, 1782/1, 2117 and 2117/1. Inclinometer A/B and C/D Profiles for Borehole 5 for the period 30th June 1989 to 12th May 1992 (reproduced from RTA reports with permission)...... 9-26 Figure 9.10. Site 065, RTA Project G1782, landslide near the intersection of Lawrence Hargrave Drive and Fifth Avenue. Inclinometer 5 cumulative shear displacement, rate of shear, antecedent and daily rainfall curves...... 9-28 Figure 9.11. Site 64 and 65, ARPET curves with significant antecedent rainfall values related to shear displacement...... 9-30 Figure 9.12. SLOPE/W model used for the stability assessment of Site 64, RSA Project 1569 at Scarborough, chainage 63.650km...... 9-32 Figure 9.13. SLOPE/W peak strength sensitivity analysis (assuming c = 5), for Site 64 using the Morgenstern Price method...... 9-33 Figure 9.14. SLOPE/W Back Analysis sensitivity (assuming c = 0), for Site 64 using the Morgenstern Price method...... 9-35 4 11/06/2008, Table of Figures

Figure 9.15. SLOPE/W Back Analysis sensitivity (assuming c = 5), for Site 64 using the Morgenstern Price method...... 9-36 Figure 9.16. Segment of the Geotechnical Landscape Map G11, including Site 77. Figure 6.1 contains the legend information...... 9-41 Figure 9.17. Site 77 Land Instability database Site Data Record form...... 9-42 Figure 9.18. Site 77, Borehole MA1, selected inclinometer displacement vector profiles...... 9-51 Figure 9.19. Site 77, Borehole MA2, selected inclinometer displacement vector profiles...... 9-52 Figure 9.20. Site 77, Borehole MA3, selected inclinometer displacement vector profiles...... 9-53 Figure 9.21. Site 77, Borehole MA5, selected inclinometer displacement vector profiles...... 9-54 Figure 9.22. Site 77, Inclinometer monitoring cumulative shear displacement, rate of shear, standpipe water levels, antecedent rainfall curves and daily rainfall totals for 1990 to 1996...... 9-57 Figure 9.23. Site 77, Inclinometer monitoring cumulative shear displacement, rate of shear, standpipe water levels, antecedent rainfall curves and daily rainfall totals for 1995 and 1996...... 9-60 Figure 9.24. Site 77, ARPET Curves with significant antecedent rainfall values related to shear displacement...... 9-62 Figure 9.25. SLOPE/W model used for the stability assessment of Site 77, the Morrison Avenue landslide...... 9-64 Figure 9.26. SLOPE/W peak strength sensitivity analysis (assuming c = 5kPa), for Site 77 using the Morgenstern Price method...... 9-66 Figure 9.27. SLOPE/W residual strength sensitivity analysis (assuming c = 0kPa), for Site 77 using the Morgenstern Price method...... 9-69 Figure 9.28. Segment of the Geotechnical Landscape Map J9, including site 134. Borehole WH2, WH10 and WH14 have been manually added to this figure by the writer. Figure 6.1 contains the legend information...... 9-72 Figure 9.29. Site 134 Land Instability database Site Data Record form ...... 9-73 Figure 9.30. Site 134 Borehole WH2, selected inclinometer displacement vector profiles...... 9-80 Figure 9.31. Site 134 Borehole WH10, selected inclinometer displacement vector profiles...... 9-81 Figure 9.32. Site 134 Borehole WH13, selected inclinometer displacement vector profiles...... 9-82 Figure 9.33. Site 134 Borehole WH14, selected inclinometer displacement vector profiles...... 9-83 Figure 9.34. Site 134 Borehole WH15, selected inclinometer displacement vector profiles...... 9-84 Figure 9.35. Site 134, Inclinometer monitoring cumulative shear displacement, rate of shear, standpipe water levels, daily rainfall totals and antecedent rainfall curves for the period 1990 to 1996...... 9-87 Figure 9.36. Site 134, Inclinometer monitoring cumulative shear displacement, rate of shear, standpipe water levels, daily rainfall totals and antecedent rainfall curves for the period December 1990 to March 1992...... 9-89 Figure 9.37. Site 134, Inclinometer monitoring cumulative shear displacement, rate of shear, standpipe water levels, daily rainfall totals and antecedent rainfall curves for the period March 1995 to May 1996...... 9-90 Figure 9.38. Site 134, ARPET curves with significant antecedent rainfall values related to shear displacement...... 9-92 Figure 9.39. SLOPE/W model used for the stability assessment of Site 134, the Woonona Heights landslide...... 9-94 Figure 9.40. SLOPE/W peak strength sensitivity analysis (assuming c = 5kPa), for Site 134 using the Morgenstern Price Method...... 9-96

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Figure 9.41. SLOPE/W residual strength sensitivity analysis (assuming c = 0kPa), for Site 134 using the Morgenstern Price Method ...... 9-97 Figure 9.42. ARPET curves and combined ‘peak, high and accelerating’ data for all sites...... 9-102 Figure 9.43. ARPET curves and combined ‘failure’ data for the three case study sites...... 9-103 Figure 9.44. ARPET curves and combined ‘slow, slowing and stopped’ data for all sites...... 9-104 Figure 10.1. The Proposed Risk Management Process...... 10-2 Figure A4.1. Geotechnical Landscape Map B13 Geology and Landslide spatial summary...... A-36 Figure A4.2. Geotechnical Landscape Map C12 Geology and Landslide spatial summary...... A-36 Figure A4.3. Geotechnical Landscape Map C13 Geology and Landslide spatial summary...... A-37 Figure A4.4. Geotechnical Landscape Map B13 Geology and Landslide spatial summary...... A-37 Figure A4.5. Geotechnical Landscape Map D13 Geology and Landslide spatial summary...... A-38 Figure A4.6. Geotechnical Landscape Map E11 Geology and Landslide spatial summary...... A-38 Figure A4.7. Geotechnical Landscape Map E12 Geology and Landslide spatial summary...... A-39 Figure A4.8. Geotechnical Landscape Map E13 Geology and Landslide spatial summary...... A-39 Figure A4.9. Geotechnical Landscape Map F11 Geology and Landslide spatial summary...... A-40 Figure A4.10. Geotechnical Landscape Map F12 Geology and Landslide spatial summary...... A-40 Figure A4.11. Geotechnical Landscape Map G11 Geology and Landslide spatial summary...... A-41 Figure A4.12. Geotechnical Landscape Map G12 Geology and Landslide spatial summary...... A-41 Figure A4.13. Geotechnical Landscape Map H10 Geology and Landslide spatial summary...... A-42 Figure A4.14. Geotechnical Landscape Map H11 Geology and Landslide spatial summary...... A-42 Figure A4.15. Geotechnical Landscape Map I9 Geology and Landslide spatial summary...... A-43 Figure A4.16. Geotechnical Landscape Map I10 Geology and Landslide spatial summary...... A-43 Figure A4.17. Geotechnical Landscape Map J9 Geology and Landslide spatial summary...... A-44 Figure A4.18. Geotechnical Landscape Map J10 Geology and Landslide spatial summary...... A-44 Figure A4.19. Geotechnical Landscape Map K9 Geology and Landslide spatial summary...... A-45 Figure A4.20. Geotechnical Landscape Map L8 Geology and Landslide spatial summary...... A-45 Figure A4.21. Geotechnical Landscape Map L9 Geology and Landslide spatial summary...... A-46 Figure A4.22. Geotechnical Landscape Map M7 Geology and Landslide spatial summary...... A-46 Figure A4.23. Geotechnical Landscape Map M8 Geology and Landslide spatial summary...... A-47 Figure A4.24. Geotechnical Landscape Map M9 Geology and Landslide spatial summary...... A-47 Figure A4.25. Geotechnical Landscape Map N7 Geology and Landslide spatial summary...... A-48 Figure A4.26. Geotechnical Landscape Map N8 Geology and Landslide spatial summary...... A-48

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