Technical Assistance Consultant’s Report Project Number: 44167-012 December 2013 Bangladesh: Main River Flood and Bank Erosion Risk Management Program (Financed by the Japan Fund for Poverty Reduction) Prepared by Northwest Hydraulic Consultants, Canada In association with Resource Planning and Management Consultants Ltd., Bangladesh For Bangladesh Water Development Board This consultant’s report does not necessarily reflect the views of ADB or the Government concerned, and ADB and the Government cannot be held liable for its contents. (For project preparatory technical assistance: All the views expressed herein may not be incorporated into the proposed project’s design. Government of the People's Republic of Bangladesh Bangladesh Water Development Board Project Preparatory Technical Assistance No. 8054 BAN Main River Flood and Bank Erosion Risk Management Program Final Report, Annex F Design Issues September 2013 In association with Resource Planning & Management Consultants Ltd. Asian Development Bank Funded by the Japan Fund for Poverty Reduction Government of the People’s Republic of Bangladesh Bangladesh Water Development Board Project Preparatory Technical Assistance 8054 BAN Main River Flood and Bank Erosion Risk Management Program Final Report, Annex F Design Issues September 2013 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program Document Status Title: Designs Issues, Annex F Annex F1 Geotechnical Investigations Principal Author: Ahsanul Jalil Khan Contributions: Annex F2 Technical Designs for Tranch‐1 Work Principal Author: Mukhles uz Zaman Contributions: Final version: August 2013 Document Development Draft Final June 2013 Final R1, 15 August 2013 Justify and page setup R2, 21 August 2013 Combined F1 & F2 two doc files and page setup R3, 28 August 2013 Inserted Two Appendix R4, 01 September 2013 Format cover page and header and footer R5, 22 September 2013 Checked for final print R6, 30 September 2013 Added Annexures page R7, 28 February 2014 Reprinted R6 Reviewed by: Page ii September 2013 F1 Geotechnical Investigations MAIN REPORT ANNEXES Annex A Priority Sub‐reach Selection & Sub‐reach Descriptions Annex A1 Priority Sub‐reach Selection Annex A2 Sub‐reach Description Annex B Background Data Annex B1 National Water Resources Database Annex B2 Socio‐economic Data Annex B3 Surveys and Field Visits Annex C Institutional and Financial Assessment Annex D Hydrology and Flood Modelling Annex E River and Charland Morphology and River Engineering Annex F Design Issues Annex F1 Geotechnical Investigations Annex F2 Technical Designs Annex G Economic Feasibility Annex G1 Project Cost Annex G2 Economic Assessment Annex H Implementation and Procurement Planning Annex I Social Gender Equity Strategy & Action Plan Annex J Environmental Impact Assessment Annex K Involuntary Resettlement Annex K1 Resettlement Framework Annex K2 Resettlement Plan Page iii PPTA 8054: Main River Flood and Bank Erosion Risk Management Program Page iv September 2013 Asian Development Bank Funded by the Japan Fund for Poverty Reduction Government of the People’s Republic of Bangladesh Bangladesh Water Development Board Project Preparatory Technical Assistance 8054 BAN Main River Flood and Bank Erosion Risk Management Program Final Report, Annex F1 Geotechnical Investigations September 2013 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program Page vi September 2013 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program Table of Contents 1 Introduction ................................................................................................................................... 1 1.1 Background ........................................................................................................................................ 1 1.2 Geo‐technical Investigation ............................................................................................................... 2 2 Study sites with and Soil Data ........................................................................................................ 3 2.1 Borehole Location .............................................................................................................................. 3 2.2 Field and Laboratory Tests ................................................................................................................. 7 2.3 Discussion of Results ........................................................................................................................ 10 3 Sub‐Soil Profile ............................................................................................................................. 11 4 Embankment stability: ................................................................................................................. 16 4.1 Introductory Remarks ...................................................................................................................... 16 4.2 Stability analysis ............................................................................................................................... 17 4.3 Settlement (of foundation soil beneath embankment) ................................................................... 18 4.4 Check for seepage flow .................................................................................................................... 20 4.5 Check for horizontal sliding/pore water pressure within the embankment ................................... 20 4.6 Stability against Earthquake/Check for liquefactions ...................................................................... 21 5 Riverbank Stability ....................................................................................................................... 22 5.1 Data and calculation method ........................................................................................................... 22 5.1.1 Slope angles and Soil characteristics .................................................................................... 22 5.1.2 Calculation method ............................................................................................................... 23 5.2 Calculated Scenarios ........................................................................................................................ 24 5.2.1 Existing Riverbank ................................................................................................................. 24 5.2.2 Designed river bank .............................................................................................................. 25 5.3 Summary and Conclusion ................................................................................................................ 28 6 Summery RBP .............................................................................................................................. 29 6.1 General Geotechnical features ........................................................................................................ 29 6.2 Flood embankment stability ............................................................................................................ 29 6.3 Riverbank Protection ....................................................................................................................... 29 7 References ................................................................................................................................... 30 Page vii PPTA 8054: Main River Flood and Bank Erosion Risk Management Program List of Tables Table 2‐1: Location, Bore‐hole depth & coordinate with ground and ground water elevations (Koizuri‐ Hurasagar section) ....................................................................................................................................... 3 Table 2‐2: Location, Bore‐hole depth & Coordinate with ground and ground water elevations (Chouhali‐ Nagarpur section) ........................................................................................................................................ 5 Table 2‐3: Location, Bore‐hole depth & Coordinate with ground and ground water elevations (Jafarganj‐ Bachamara section) ..................................................................................................................................... 5 Table 2‐4: Location, Bore‐hole depth & Coordinate with ground and ground water elevations (Enayetpur‐Koizuri section) ......................................................................................................................... 6 Table 2‐5: KH‐4 Field and Corrected SPT (N’) .............................................................................................. 8 Table 2‐6: KH‐ 9 Field and Corrected SPT (N’) .............................................................................................. 8 Table 2‐7: KH‐40 Field and Corrected SPT (N’) ............................................................................................ 8 Table 2‐8: JB‐2 Field and Corrected SPT (N’) ............................................................................................... 8 Table 2‐9: CN‐10 Field and Corrected SPT (N’) ............................................................................................ 9 Table 2‐10: CN‐13 Field and Corrected SPT (N’) .......................................................................................... 9 Table 2‐11: EK‐5 Field and Corrected SPT (N’) ............................................................................................