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’) ...... 9 Table 2‐12: EK‐10 Field and Corrected SPT (N’) ...... 10 Table 5‐1: Results of the calculation for existing Slopes ...... 24 Table 5‐2: Case 1‐ 19 m river bed ...... 26 Table 5‐3: Case 2‐ 39 m river bed ...... 26 Table 5‐4: Results of calculation for designed slopes ...... 27
Figures
Figure 1‐1 (a&b): Typical Sections of Proposed Flood Embankment ...... 2 Figure 2‐1: Satellite Image of Project Location ...... 6 Figure 2‐2: Satellite Image of Bore‐Hole Location ...... 7 Figure 3‐1: Bore Hole Log of Koizuri‐Hurashagar (KH) ...... 12 Figure 3‐2: Bore Hole Log of Enayetpur‐Koizuri (EK) ...... 13 Figure 3‐3: Bore Hole Log of Chauhali‐Nagarpur (CN) ...... 14 Figure 3‐4: Bore Hole Log of Jafarganj‐Bachamara (JB) ...... 15 Figure 5‐1: Profile of the cross sections at the Jamuna River right bank ...... 22 Figure 5‐2: Profile of the cross sections at the Jamuna River left bank ...... 22 Figure 5‐3: Safety factor for 35m slopes Figure 5‐4: Safety factor for 15 m slopes ...... 23 Figure 5‐5: Dimensions of existing slopes ...... 24 Figure 5‐6: Typical slip circles at an existing slope ...... 25 Figure 5‐7: Slope dimensions of designed slopes ...... 26 Figure 5‐8: Safety factor for 35m slopes Figure 5‐9: Safety factor form 15 slopes ...... 26 Figure 5‐10: Typical slip circles at a designed slope...... 27 Figure 6‐1: Comparison designed slope to existing river profile ...... 30
Page viii September 2013 F1 Geotechnical Investigations
1 Introduction
1.1 Background The Asian Development Bank (ADB) is undertaking a feasibility assessment of a flood and riverbank erosion risk management program covering parts of the main rivers of Bangladesh financed by the Japan Fund for Poverty Reduction (JFPR). The objective of the Main River Flood and Bank Erosion Risk Management Program (MRP) is to reduce the riverbank erosion and flood risks to the adjacent flood plains while maximizing economic activities in a sustainable and environmentally acceptable manner. Existing flood embankments dominantly fail from riverbank erosion, and as such the stabilization of the river pattern is a cornerstone of reducing the flood risk. The MRP builds on and extends the activities of the Jamuna‐Meghna River Erosion Mitigation Project (JMREMP) (ADB, 2002), implemented in different phases from January 2003 until June 2011. In addition, a similar project, the Assam Integrated Flood and Riverbank Erosion Risk Management Investment Project (AIFRERMIP; ADB, 2010) provides important insight into a number of relevant project elements and processes especially integrating disaster risk management measures related to flood and riverbank erosion risk management under the dictate of the Integrated Water Resources Management (IWRM) framework.
Subsequent to the preliminary assessment of geo‐technical aspects certain analytical evaluations have been made in order to obtain important and relevant geo‐technical parameters. The presentation of these parameters is basically on the assumption of fairly uniform sub soil strata and their properties and characteristics generally observed in the locality.
The main objective of present study is to formulate parameters for feasibility design of stability of the proposed flood embankment/levy/ dykes with some hydraulic structures having regulatory functions.
The report also includes study and design (stability) for River Bank protection measures separately in the later section.
The following basic data/ information were used as guide line for preliminary analysis of stability – (a) HFL – 100 years frequency in Brahmaputra Jamuna 50 years frequency in Boral and Hurasagar (b) Ground level along the alignment of the proposed embankment (c) Geo‐technical data – i) Bore holelogs ii) Field‐lab test results iii) BWDB data iv) Results of PIRDP of JMREMP investigation and analysis (d) Proposed options for typical x‐sections of embankment as shown in Figure 1.1.
The comments and observation received from BWDB design office were answered through a note on Design Criteria as Appendix‐IV and Comments and Observance as Appendix‐V in Annex F2.
Page 1 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
Typical Cross section of Embankment ( Height- 5m)
Carriage width 1.5 Verge 1 Shoulder
1 2 3 0.75 1.5 5.5 Sand fill 1 3.5 2.5
Sand fill 60 cm excavated
15.0 3.2 3.0 10.0 8.75 39.95
Typical Cross section of Embankment ( Height- 5m)
Temporary Shelter 1.0 Carriage width 1.5 Verge 1 1 Shoulder 2 2 0.75 1.5 5.5 4.0 1 Sand fill 1 3.5 2 2.5
Sand fill 60 cm excavated
10.0 8.0 2.0 3.2 3.0 10.0 8.75 44.95
Figure 1‐1 (a&b): Typical Sections of Proposed Flood Embankment
1.2 Geo‐technical Investigation It is essential to understand the nature and behavior of the soil forming the river bank and also bed materials for the development of a bank protection work. In the present report relevant geo‐technical aspects are studied for analysis of flood embankment along the river bank, some distance apart from the existing bank. However, it is to be noted though that the anticipated failure modes of river bank are (a) erosion of soil due to wave and/or river current and sliding of slope due to instability induced by bed erosion or undercutting below water level. These modes of failure may take place where slope angle is not consistent with geo‐technical conditions prevailing at the site. A soil exploration program was therefore undertaken to investigate the sub soil condition at the selected project sites for main river flood embankment and bank erosion risk management program.
Accordingly, for the preliminary project formulation and feasibility study; a number of bore‐holes were explored through the Ground Water Hydrology Division of BWDB, during November 2011 to February 2012.
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2 Study sites with and Soil Data
2.1 Borehole Location At right bank of river Jamuna, 40 Bore Holes (BH) designated as KH‐1 to KH‐40, at Koizuri to Hurasagar and Bherakhola to Baghabari port in Sirajganj District. At right bank of river Jamuna, 14 BH designated as EK‐1 to EK‐14, from Enayetpur to Koizuri in Sirajganj district. At left bank of river Jamuna, 19 BH designated as CN‐1 to CN‐19 from Chouhali to Nagarpur, in Tangail District At left Bank of river Jamuna, 10 BH designated as JB‐1 to JB‐10 from Jafarganj to Bachamara in Manikganj District.
Depth of Bore‐hole, locations with co‐ordinates are shown in Table 2.1 and Bore Hole (BH) locations on Satellite image with co‐ordinates are shown in Figure 2.2.
Table 2‐1: Location, Bore‐hole depth & coordinate with ground and ground water elevations (Koizuri‐Hurasagar section) District Koizuri– Coordinates Upazila Depth Gr. Elv. GWT Hurasagar (KH) (m) PWD(m) PWD(m) KH1 N24°10´33.6´ E 89°41'28´´ Shajadpur 30 10.34 3.25 N673456 E468943 KH2 N24°10´21.8´´ E 89°41'17´´ Shajadpur 20 10.25 3.85 N673090 E468625 KH3 N24°10´04.0´ E 89°41'17´´ Shajadpur 30 10.16 2.87 N672550 E468627 KH4 N24°9´54.5´´ E 89°41'07´´ Shajadpur 20 10.12 2.998 N672252 E468333 KH5 N24°9´45.0´´ E 89°40'53´´ Shajadpur 30 10.35 3.28 N671963 E467922 KH6 N24°9´31.9´´ E 89°40'42´´ Shajadpur 20 9.94 2.64 N671558 E467628 KH7 N24°9´18.1´´ E 89°40'31´´ Shajadpur 30 10.17 3.28 N671136 E467305 KH8 N24°9´04.9´´ E89°40'23.5´´ Shajadpur 20 10.35 2.64
N670710 E467096 KH9 N24°8´52.6´´ E89°40'10.8´´ Shajadpur 30 10.15 3.28
Sirajganj N670348 E466732 KH10 N24°8´39.7´´ E89°40'0.7´´ Shajadpur 20 9.45 3.125 N669947 E466434 KH11 N24°8´26.9´´ E89°39'57.0´´ Shajadpur 30 10.27 2.64 N669550 E466428 KH12 N24°8´09.8´´ E 89°40'2.6´´ Shajadpur 20 10.25 2.69 N669044 E466490 KH13 N24°7´53.1´´ E89°39'58.3´´ Shajadpur 30 10.11 2.82 N668530 E466365 KH14 N24°6´37.6´´ E89°39'56.9´´ Shajadpur 20 10.05 2.52 N668043 E466328 KH15 N24°7´20.5´´ E89°39'55.9´´ Shajadpur 30 10.09 2.82 N667521 E466301 KH16 N24°7´03.7´´ E89°39'52.5´´ Shajadpur 20 9.81 2.52 N667010 E466215 KH17 N24°6´48.5´´ E89°39'46.9´´ Shajadpur 30 9.43 2.95
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District Koizuri– Coordinates Upazila Depth Gr. Elv. GWT Hurasagar (KH) (m) PWD(m) PWD(m) N666539 E466038 KH18 N24°6´33.0´´ E89°39'52.7´´ Shajadpur 20 10.03 2.69 N666063 E466191 KH19 N24°6´16.4´´ E89°39'01.6´´ Shajadpur 30 10.13 3.115 N665587 E466322 KH20 N24°6´01.5´´ E89°40'09.4´´ Shajadpur 20 10.06 2.69 N665098 E466464 KH21 N24°5´47.6´´ E89°40'14.0´´ Shajadpur 30 10.11 3.125 N664665 E466674 KH22 N24°5´33.3´´ E 89°40'.0´´ Shajadpur 20 10.07 2.62 N664196 E466808 KH23 N24°5´14.5´´ E89°40'12.0´´ Shajadpur 30 9.87 3.125 N663669 E466759 KH24 N24°5´04.0´´ E89°40'01.0´´ Shajadpur 20 9.68 2.69 N663313 E466428 KH25 N24°4´51.6´´ E89°39'55.4´´ Shajadpur 30 9.49 3.125 N662933 E466278 KH26 N24°4´36.3´´ E89°39'46.6´´ Shajadpur 20 9.56 2.515 N662476 E466023 KH27 N24°4´20.4´´ E89°39'39.4´´ Shajadpur 30 8.58 3.1 N663669 E466759 KH28 N24°4´30.4´´ E89°39'24.8´´ Shajadpur 20 7.72 3.4 N662300 E467148 KH29 N24°4´38.5´´ E89°39'15.1´´ Shajadpur 30 7.45 3.45 N662565 E465128 KH30 N24°4´45.6´´ E89°38'56.8´´ Shajadpur 20 7.51 2.49 N662763 E464624 KH31 N24°5´57.2´´ E89°38'33.7´´ Shajadpur 30 9.25 2.82 N663120 E464140 KH32 N24°5´08.1´´ E89°38'22.3´´ Shajadpur 20 7.95 3.1 N663461 E463652 KH33 N24°5´20.4´´ E89°38'04.0´´ Shajadpur 30 9.15 2.72 N663831 E463136 0KH34 N24°5´31.7´´ E89°37'46.9´´ Shajadpur 20 8.31 2.82 N664180 E462651 KH35 N24°5´44.2´´ E89°37'29.0´´ Shajadpur 30 9.05 3.15 N664568 E462148 KH36 N24°4´59.8´´ E89°37'11.5´´ Shajadpur 20 8.11 2.95 N665062 E461656 KH37 N24°4´09.2´´ E89°39'35.4´´ Shajadpur 40 9.07 3.18 N661642 E465689 KH38 N24°5´34.0´´ E89°39'58.5´´ Shajadpur 40 10.01 3.25 N662408 E466347 KH39 N24°5´01.2´´ E89°40'21.4´´ Shajadpur 40 10.12 3.10 N663225 E466960 KH40 N24°5´05.0´´ E89°40'26.1´´ Shajadpur 40 9.81 3.1 N664214 E465417
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Table 2‐2: Location, Bore‐hole depth & Coordinate with ground and ground water elevations (Chouhali‐Nagarpur section) District Chouhali‐ Coordinates Upazila Depth Gr. Elv. GWT Nagarpur (m) PWD(m) PWD(m) CN‐1 N24°18´07.3´´ E89°47´42.8´´ Omarpur 40 12.74 3.1 CN‐2 N24°17’38.2´´ E89°48´38.7´´ Norshinghopur 40 12.07 3.1 CN‐3 N24°17´08.9´’ E89°48´20.2´´ Dholabari 40 12.12 3.1 CN‐4 N24°16´44.2´´ E89°47´56.6´´ Kachua 40 11.63 3.1 CN‐5 N24°16´11.2´´ E89°47´51.4´´ Kachua 40 11.07 3.1 CN‐6 N24°15´42.5´´ E89°48´21.6´´ Degreehogra 40 12.14 3.1 CN‐7 N24°15´08.6´´ E89°48´19.5´´ Degreehogra 40 12.6 3.1 CN‐8 N24°14´32.2´´ E89°48´21.2´´ Alokdia 40 12.19 3.05 CN‐9 N24°14´00.0´´ E89°48´25.0´´ Alokdia 40 12.15 3.41
CN‐10 N24°13´29.4´´ E89°48´33.6´´ Ichapara 40 12.1 3.25
Tangail CN‐11 N24°12´56.6´´ E89°48´46.9´´ Rashidpur 40 12.07 3.56 CN‐12 N24°12’22.9´´ E89°48´55.3´´ Rashidpur 40 12 3.43 CN‐13 N24°12´14.2´´ E89°47´10.1´´ Chalchar 40 10.9 3.71 CN‐14 N24°11´40.7´´ E89°47´13.5´´ Misrogati 40 10.84 3.56 CN‐15 N24°11´07.6´´ E89°47´26.1´´ Dhalpakhla 40 11.11 3.25 CN‐16 N24°10´33.1´´ E89°47´33.1´´ Mahmoodpur 40 11 3.41 CN‐17 N24°09´58.8´´ E89°47´39.6´´ Mahmoodpur 40 11.02 3.1 CN‐18 N24°09´22.9´´ E89°47´42.7´´ Dolai 40 10.8 3.41 CN‐19 N24°08´45.7´´ E89°48´53.4´´ KhasKaulia 40 10.9 3.71
Table 2‐3: Location, Bore‐hole depth & Coordinate with ground and ground water elevations (Jafarganj‐ Bachamara section) Distric Jafarganj‐ Coordinates Upazila Depth Gr. Elv. GWT t Bachamara (m) PWD(m) PWD(m) JB1 N23°53´24.2´´ E89°45´42.3´´ Shibaloy 40 10 4.64 JB2 N23°53´58.4´´ E89°45´21.6´´ Shibaloy 40 9.2 3.71 JB3 N23°54´49´´ E89°45´43.2´´ Daulotpur 40 9 4.01 JB4 N23°55´40.2´´ E89°45´47.5´´ Daulotpur 40 8.5 3.76
JB5 N23°56´8.2´´ E89°46´4.1´´ Daulotpur 40 8.6 3.168 JB6 N23°57´8.4´´ E89°46´25.7´´ Daulotpur 40 10 3.84 Manikganj JB7 N23°57´56´´ E89°46´33.4´´ Daulotpur 40 8.8 3.86 JB8 N23°58´33.6´´ E89°46´33.8´´ Daulotpur 40 9.5 4.01 JB9 N23°59´17.4´´ E89°46´17.2´´ Daulotpur 40 10.2 4.47 JB10 N23°59´31.5´´ E89°45´29.8´´ Daulotpur 40 8 4.62
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Table 2‐4: Location, Bore‐hole depth & Coordinate with ground and ground water elevations (Enayetpur‐Koizuri section) Enayetpur‐ Gr. Elv. GWT District Co‐ordinates Upazila Depth Koizuri PWD(m) PWD(m) EK‐1 N24°11´28.2´´ E89°41´52.7´´ Enayetpur 40 10.35 3.48 N675136 E475667 EK‐2 N24°21´08.2´´ E89°42´02.7´´ Enayetpur 40 10.51 3.33 N676359 E469903 EK‐3 N24°12´43.9´´ E89°78´26.4´´ Enayetpur 40 10.19 3.61 N677461 E470567 EK‐4 N24°13´17.4´´ E89°71´48.8´´ Enayetpur 40 10.62 3.56 N678488 E471148 EK‐5 N24°13´58.7´´ E89°43´42.59´´ Enayetpur 40 10.81 3.56 N679750 E571495 EK‐6 N24°14´37.5´´ E89°43´20.3´´ Enayetpur 40 10.22 3.4045 N680954 E472095
EK‐7 N24°15´06.1´´ E89°44´47.9´´ Enayetpur 40 10.2 3.43 N682100 E473722 EK‐8 N24°15´14.8´´ E89°45´18.1´´ Enayetpur 40 10.83 3.1 Sirajganj N683100 E475306 EK‐9 N24°15´47.8´´ E89°45´14.1´´ Enayetpur 40 10.37 4.045 N684073 E475702 EK‐10 N24°16´19.2´´ E89°45´28.1´´ Enayetpur 40 10.45 3.15 N685034 E475907 EK‐11 N24°16´50.5´´ E89°45´35.2´´ Enayetpur 40 10.89 3.43 N686075 E476154 EK‐12 N24°17´24.2´´ E89°45´43.8´´ Enayetpur 40 11.17 3.56 N687047 E476074 EK‐13 N24°18´32.00´´ E89°45´34.8´´ Enayetpur 40 11.47 3.25 N688150 E475901 EK‐14 N24°19´21.8´´ E89°45´26.4´´ Enayetpur 40 11.64 3.125 N689701 E475667
Figure 2‐1: Satellite Image of Project Location
Page 6 September 2013 F1 Geotechnical Investigations
Figure 2‐2: Satellite Image of Bore‐Hole Location
2.2 Field and Laboratory Tests Sub‐soil investigation conducted in field presents bore‐hole logs with ground level (GL), Standard Penetration Tests (at every 1.5 meter) and stratification with lithological description. Laboratory test results include grain size distribution curves, atterberg limit tests, consolidation parameters, natural moisture contents, specific gravity, density test with OMC maximum dry density, unconfined compression (U.C) tests and unconsolidated undrained (U.U) triaxial compression tests. Very brief analysis has been made on the result of the above soil investigation reports and some salient feature are presented in Tables 2.5 ‐ 2.12. Observation and findings of previous investigations and study conducted under JMREMP in 1992, 1993 and also during 2001 and 2006 were reviewed in the present study.
Page 7 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
Soil constituents (with some parameters)
Table 2‐5: KH‐4 Field and Corrected SPT (N’)
Depth (m) C (%) M (%) S (%) Soil Types NMC 2 70 30 M+FS 0.045 0.009 5 58 42 CL/ML+FS 0.06 0.01 7.5 7 93 FS 0.14 0.008 9 7 93 FS 0.14 0.008 12.2 8 92 FS 0.135 0.09 15 8 92 FS 0.149 0.074 18.3 4 96 FS 0.147 0.085
Table 2‐6: KH‐9 Field and Corrected SPT (N’)
Depth (m) C (%) M (%) S (%) Soil Types NMC 2 66 34.1 SANDYSILT +NP+ML 0.04 0.005 3 56 44 VFS+MC+NP 0.08 0.006 7.5 11 89 FS 0.14 0.065 10 14 86 FS 0.125 0.060 15 6 94 FS 0.13 0.090 18.3 8 92 FS 0.125 0.08 23 6 94 FS 0.140 0.075 30 4 96 FS 0.149 0.090
Table 2‐7: KH‐40 Field and Corrected SPT (N’)
Depth (m) C (%) M (%) S (%) Soil Types NMC 2 88 12 CL+ML 0.01 0.0015 3 68 32 ML+CL 0.045 0.0092 5 48 52 ML+FS 0.08 0.0175 4 18 82 FS 0.10 0.04 11 16 84 FS 0.125 0.05 15 15 85 FS 0.125 0.06 23 8 92 FS 0.140 0.08 30 16 84 FS 0.12 0.06 40 2 98 FS 0.149 0.092
Table 2‐8: JB‐2 Field and Corrected SPT (N’)
Depth (m) C (%) M (%) S (%) Soil Types NMC 1.5 44 56 0.08 3 42 58 CH 0.085 5 30 70 FS+M 0.095 6 12.1 89 FS 0.15 6.7 14 86 FS 0.135 10 9 91 FS 0.163 24.16 2.66 12 9 91 FS 0.155 24.96 1.66 15 10 90 FS 0.155 18.6 9 91 FS 0.155 23 9 91 FS 0.155 26 9.5 90.5 FS 0.163 30 12 88 FS 0.149 36 12 88 FS 0.155
Page 8 September 2013 F1 Geotechnical Investigations
Table 2‐9: CN‐10 Field and Corrected SPT (N’)
Depth( m) C(%) M (%) S (%) Soil Types NMC 2 75 25 ML(NP) 0.045 0.01 3‐4 76 24 ML(NP) 0.037 0.007 5 72 28 ML+SP 0.04 0.01 20.43 2.665 6.5 76 24 ML+SP 0.045 0.01 12.1 2.663 10 14 36 ML 0.155 0.06 8 78 22 ML 0.0455 0.009 12.5 70 30 FS 0.052 0.009 15 10 90 FS 0.18 0.08 20 30 70 FS 0.12 0.025 23 28 72 FS 0.125 0.03 26 10 90 FS 0.18 0.075 30 9 91 FS 0.175 0.08 35 8 92 FS 0.18 0.085
Table 2‐10: CN‐13 Field and Corrected SPT (N’)
Depth (m) C (%) M (%) S (%) Soil Types NMC 2 74 26 ML 0.04 0.009 3.5 72 28 ML(NP) 0.052 0.012 4.5 76 24 ML 0.046 0.009 6.5 30 70 FS 0.13 0.025 10 25 75 FS 0.125 0.04 12 24 76 FS 0.125 0.04 15 24 76 FS 0.130 0.05 20 16 84 FS 0.12 0.055 25 4 96 FS 0.21 0.12 27 6 94 FS(SP) 0.2 0.10 30 18 82 FS(SP) 0.125 0.05 35 16 84 FS(SP) 0.14 0.05 38 18 82 FS(SP) 0.135 0.055
Table 2‐11: EK‐5 Field and Corrected SPT (N’)
Depth (m) C (%) M (%) S (%) Soil Types NMC 1.5 47 53 FS+M+NP 0.08 0.025 3 66 34 ML+FS 0.058 0.018 5 66 34 M+FS 0.058 0.018 6.5 14 86 FS 0.156 0.06 8 12 88 FS 0.152 0.10 10 10 90 FS 0.149 0.07 11 4 96 FS 0.14 0.092 12.5 6 94 FS 0.17 0.088 13.7 4 96 FS 0.125 0.088 15 2 98 FS 0.135 0.092 18.5 4 96 FS 0.149 0.085 22 6 94 FS 0.125 0.08 24.7 8 92 FS 0.155 0.085 30 2 98 FS 0.152 0.10 35 2 98 FS 0.149 0.093 38 2 98 FS 0.155 0.095 40 2 98 FS 0.149 0.095
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Table 2‐12: EK‐10 Field and Corrected SPT (N’)
Depth (m) C (%) M (%) S (%) Soil Types NMC 1.5 8 92 FS 0.22 0.09 4.5 2 98 FS 0.149 0.092 10.5 2 98 FS 0.175 0.10 12.5 6 94 FS 0.156 0.088 15 4 96 FS 0.149 0.095 20 4 96 FS 0.152 0.088 25 6 94 FS 0.154 0.085 30 4 96 FS 0.149 0.09 35 6 94 FS 0.140 0.083 40 4 94 FS 0.149 0.09
NOTE: C= Clay minerals M= Silt S= Sand VFC= Very fine sand FS= Fine sand NP= Non‐Plastic ML= Silt low plastic CL= Clay low Plastic CH= Clay High Plastic MH= Silt High Plastic
2.3 Discussion of Results The BWDB undertook fairly comprehensive sub‐soil investigation all along the proposed alignment for flood embankment and river bank protection works. The Geotechnical investigation performed by BWDB will time bound program (carried and hurriedly) resulting in some uncertainties about the accuracy of the findings. But as mentioned earlier, the sub soil composition in the project location is generally uniform. However, subsoil data obtained and used in the analysis appear to be reasonably consistent with the past reports and results. Further, it is expected the factor of safety provided would compensate for local and general uncertainties
Further due to large distances between the bore‐holes (300m to about 400m), it may be worthwhile to undertake a limited number of additional bore‐holes before finalizing the design of embankment for some specific locations only.
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3 Sub‐Soil Profile
Figure 2.2 shows the Bore‐hole from 4 (four) locations referred earlier. Detailed bore‐hole logs are shown in Figure 3.1‐3.4. In each location (KH, EK, CN, JB) It is seen that the upper part of the soil (i.e. generally on average above RL +4.00 m PWD) is mostly dsilt an clay (CL, ML) type with varying quantities of fine to very fine sand (Non‐cohesive). This strata is underlain by very fine to fine sand (non‐cohesive) with little to trace silt and mica. The above feature is also evident in Table 2‐1 from the plot of and against depth for different Bore‐holes (Presented in Tables 2.5‐2.12). The SPT"N" Values for different Boreholes with corrected “ ” values are presented in Appendix 2, Tables A2.1 to A2.4.
The following observation can be highlighted:
The sub‐surface soil formation consists of two layer system.
In general in all four section, the upper layer consists of fine grained soil of low to inter‐mediate plasticity with few exceptions where in it is referred to as plastic, semi‐plastic or even non‐ plastic (upto above EL+4 to+5m PWD). Broadly Classified as CL‐ML type soil
The lower part (i.e. below +4 to +5m PWD) mainly consists of very fine to fine to medium grained sands upto depth of exploration. Very thin films of mica mineral in traces were also encountered at varying depths.
Page 11 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
Figure 3‐1: Bore Hole Log of Koizuri‐Hurasagar (KH)
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Figure 3‐2: Bore Hole Log of Enayetpur‐Koizuri (EK)
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Figure 3‐3: Bore Hole Log of Chouhali‐Nagarpur (CN)
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Figure 3‐4: Bore Hole Log of Jafarganj‐Bachamara (JB)
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4 Embankment stability
4.1 Introductory Remarks The project areas are located in the delta of large rivers the Jamuna, a part of Brahmaputra river system, and the Padma. The terrain is formed by the river sediments of the flood plains. The channels frequently shift sideways due to erosion of the river banks or concentrate their discharge in other river channels. The river sediments consist of finely grained sand of medium compactness. The sand in all the project sites originate from the Himalayan Mountains and therefore consist of minerals, quartz, feldspar, rock fragments, trace heavy mineral and mica.
The amount of mica varies at different depths, which are rather inconsistent. Previous documents and study reports in the same region suggest mica content from 30% to 50% in some places. The recent BUET studies however put the figure between 7% to 11%, which seems to be reasonable [Special Report‐22 (Geotechnical) of Jamuna‐Meghna River Erosion Mitigation Project, Part‐B, November 2006]. These river sediments are more or less horizontally layered with a very small inclination of layers in downstream direction. The mica minerals and the others particles have a more stocky shape. The sedimentation of quartz, feldspar and heavy minerals is much faster than mica minerals. It is observed from previous studies; the mica minerals form a very thin film of impermeable layer above more compact minerals.
A generalized summary of drilling at the project locations show a upper clay‐silt or silt‐clay layers referred to in the this report as CL‐ML (often found to be CH‐MH) which consists of silt clay / clayey silt with low to medium plasticity. Below the upper clayey layer fine grained and poorly graded sand, referred to as SP/SM or FS, sometimes very fine sand, VFS of medium compactness are present. The sand strata has a general trend of mild increase in density from medium to dense becoming very dense at depth around 30m and below.(As evident from BH‐Logs showing SPT plots in Figure 3.1‐3.4.
Geo‐technical slope failure in clay is commonly calculated by circular failure planes. Which means during failure rotation takes planes. Sand, however, shows more ors les straight failure planes; therefore translation may take place in case of failure.
Due to cohesion, clay is able to stand vertically up to a certain depth, where as pure sand without cementation will not remain stable under normal condition. In a state of low humidity (slightly moist) the sand yma have a small cohesion due to capillary action which disappears when it is dry or saturation is above 70% or so. This apparent cohesion can therefore be considered for calculation of an existing slope, but surely not for new construction. It may be noted that this part of the report deals with new flood protection embankment fairly close to existing river banks. In the present study with regular flooding of the terrain apparent cohesion may be introduced in stability analysis. At lower levels (higher depth), due to lithification of salts cementation may result in a low effective cohesion.
The clay layer on the surface of the terrain is considered sufficiently resistant. In view of its effective shear strength (without any reduction factor) the clay is able to stand vertically up‐to a certain height (around 4m or so). It is to emphasize though that in the case of slope failure, the excess of the stability of clay cannot be transferred or related to improve the stability of the sand layer below.
The survey carried during previous study observed that the slopes for the upper clay layer was fairly steep and derived magnitude of unconfined compression strength was found to be Cu=30 ‐40 kpa. BUET study conducted during 2004 also appears to confirm this value.
The observed slope inclination at river in sand is found to be 1:2.5‐1:3 for about 50% of the project area which is expected with limit equilibrium condition. The angle of internal friction, which is the shear strength of sand in these case, are 28 ‐ 30 with very low effective cohesion estimated at c=2‐4 kpa.
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In view of the uncertainties associated with the effect of cohesion at this stage, it is ignored in the stability analysis as shown in the later illustrations. The lower strata below the fine grained clay silt formulation predominantly consist of sand (fine sand with little to trace silt) and occasional Mica. eTh layer generally is of medium density as evident from interpretation of standard penetration 'N' test values. There is mild trend of increase in density with increase in depth. Further below the density is found to be medium dense to dense becoming very dense usually below 30‐35m depth of exploration. The above observation appears to agree favorably with BUET Report including earlier reports of JMREMP and FAP (Halcrow Feasibility) Studies and those of Jamuna Bridge etc.
4.2 Stability Analysis On the basis of above information and geotechnical investigation carried out by BWDB, some preliminary stability analysis may be made for the proposed flood protection embankment and bank erosion. The slope protection and erosion control of the vulnerable river bank is not considered here and are addressed separately at a later stage.
For the purpose of analysis the following assumptions are made: Assume dredged fill material for embankment construction Embankment height 4m‐ 6m (i.e. 5m on average) Compacted fine sand with angle of internal friction =28 to 30_use 30 Embankment slope: 1:3 and 1:2.5 A factor safely fs≥ 1.4 has been considered as standard in line with previous project designs for river bank stability (PIRDP).
Assume: Dredged soil from river bed River bed material mainly fine sand/ very fine sand with silt/ silty fine sand/ silt with very fine sand occasional at shallow depths. The Feature of predominant fine particles is observed at shallow depths (5‐7m). Compacted fill material have angle of internal friction φ=28‐30 Slope angle , i.e. slope is 1:3, 1:2.5 and 1:2, considered for trial.
Under normal conditions: Factor of safety (f) against failure tan f tan , Dredged fill soil f = FS = Factor of Safety Ø 28° min. to 30°, use 30° β 5m
For Ø 28° For Ø 30° Slope 1:3, Slope 1:3, f = tan 28°/ tan 18.43° = 0.532/0.33= 1.6 f = tan 30°/tan 18.43° = 0.577/0.333 = 1.7 Slope 1:2.5, Slope 1:2.5, f = tan 28°/tan 21.80° = 0.532/0.40 = 1.33 f = tan 30°/tan 21.80° = 0.577/0.40 = 1.44 Slope 1:2, f = tan 30°/ tan 26.57° = 0.577/0.50 = 1.15
Under Submerged Condition
tan .0*8 577 f sub .0 778 .1 25 tan 18 .0* 33 sand
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Assumed: ɣ 10 /
ɣ 18 /
ɣ_ 8 / ^3
Therefore seepage will occur under submerged condition.
From the above analysis, it would appear that under normal conditions slope provision of 1:3 and 1:2.5 are adequate. Protective measure against seepage flow will be required for construction of embankment considering the fact that the only material available cheaply and in abundant quantity is very fine sand with little to some silt/clay. It may be mentioned that the upper layers of soil stratification consists of plastic to semi plastic silt or clay upto about 4m‐7m with same variation in some locations as can be seen in the sub‐soil profile. It may also be mentioned that most of the proposed project segments are fairly close to the river bank and some‐time even within (which is locally) known as char areas; Further check for any significant difference between the East bank and West bank was attempted. No significant difference was observed regarding sub‐soil and soil characteristic between east or west side locations being studied.
At this stage, under the circumstances discussed above the proposed embankment configuration considered from stability and safety consideration can be silty fine sand material with clay‐cladding all around as shown in Figure 1‐1.
It is also proposed to consider slope of the embankment as 1:3 as the preferred option. However, it is also possible to use different slopes at riverside at the second option for the flood embankment configuration as shown in Figure 1‐1.
Considering that seepage may occur under submerged condition, clay on both ends (river side and country side) should be used in order to protect the embankment from scour and erosion and also to retain the finer materials from the embankment. The thickness of the cladding be provided should not be less than 60cm (preferably 1m). The material shall be clay silt with very fine sand (trace/little) which should have a plasticity index of 10‐20% in accordance with AASHTO T90. The core material shall be spread in layers not exceeding 200mm loose and compacted by means of suitable equipment as specified (minimum 95% modified proctor).
A few other aspects of stability of the embankment are analyzed below:
4.3 Settlement (of foundation soil beneath embankment) Assuming an average height of embankment‐ 5m Slope: 1:2.5
Analysis from bore‐hole logs and field & laboratory test results tends to show susceptibility of settlement of the embankment sub‐soil formation. The upper layer generally consists of soft low plastic clayey‐silt upto a depth of about 4‐7m. Underlain by fine sand with little to no trace of silt which appear to continue below upto the depth explored (30m). Some typical geotechnical properties are considered
Page 18 September 2013 F1 Geotechnical Investigations for estimating probable settlement of the compressible layer underneath the proposed flood embankment.
Relevant properties:
° 0.85 (Initial void ratio) Saturated unit weight of soil,ɣ 17.5 / ≅18 / Submerged Unit weight of soil,ɣ 7.5 / ≅8 /
Specific gravity of Sand, 2.66 Compression Index, 0.28 Coefficient of compressibility, 4 10 / Depth of Compressible layer 6m 30%
18 x 6 108 / q at said‐height = 78 / ° 17.5 3 54 / 0.28 54 78 3.0 100 17.6 1 .85 54 If 1m of top soil is removed/ replaced by compacted: 0.28 54 78 2.5 100 14.5 1 .85 54
Case‐2 *
(0.15 2 2.74 100 ≅ 13.1
° 0.9 0.28 2.67 29.5%
17.5 5 87.5 ɣ 17.5 / ɣ 7.5 / 4 10 / Estimate for time for consolidation to and 0.197 2.5 100 1 35.63 4 10 60 60 24 0.848 2.5 100 .1157 153 50%, 0.195 4 10 3600 24 90%, 0.848
The estimated settlement in a condition (h=5cm) is found to be 17.8 cm (average) considering drainage from top and bottom (double drainage). But when about 1m of top soil is removed and replaced by quickly draining sand, the effective depth (thickness) of compressible layer is reduced where in the consolidation settlement becomes 14.4 cm (average).
Similarly with embankment height (including freeboard) of 6m and the thickness, if top compressible soil underneath is 7m, the gross settlement becomes 17.36 cm. Considering double drainage and
Page 19 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program replacement of 1m of top soil by compacted fine sand, settlement is reduced. These are elaborated in sample calculation presented. In addition time for consolidation i.e. and are also shown.
It would appear from analysis, that considering stage construction (2/3 stages), assuming an allowance (consolidation time, at least up‐to 35‐50 days), a total of maximum 150 days will be necessary for consolidation of full height of embankment over a given stretch of embankment. Important here to mention that the above assessment is based on the following considerations
a. Each stage compacted height is 2‐2.5 m b. For clay cladding method of construction will follow benching/key type technique at side slopes. c. Compressible layer below embankment base is 5‐7 m d. Settlement evaluation is based on parameters either assumed or guide line reference from limited Laboratory test results available.
4.4 Check for seepage flow Assuming, clay cladding is used as protection against erosion due to seepage, possibility of seepage through underneath the embankment base will be checked. As a first step it is proposed to remove 60 cm‐100 cm top soil to be replaced by sand (compacted).
According to Terzaghi, minimum width of base should be embankment height (H) times creep ratio (cw). The value of creep ratio is taken as 7, according to table 58.1 of Soil Mechanics in Engineering practice by Terzaghi, Peck and Mesri, 3rd edition, 1995.
Width minimum = 5m *7 =35 m Width provided in two options is greater than 35m.
Provision of compacted sand fill (100 cm) underneath the embankment is also expected to take care of seepage pressure substantially and induce flow line towards the toe.
4.5 Check for horizontal sliding/pore water pressure within the embankment Earth pressure developed (Drag force):F 0.5 18 6 K ≅120KN Frictional Resistance force at base along base of triangle “abc” R 0.5 6 2.5 6 17.5 0.42 ≅ 338KN ≫ 120KN
In order to assess the stability of the embankment for rapid draw down effect on the river side, a further detailed analysis will be made once more site specific hydrological data are available.
However, the provision of clay‐cladding along with sand fill underneath the base of the embankment should adequately bring down the flow (works) line towards the toe‐line. The overall total width of the embankment in expected to reduce significantly the little seepage force that may develop.
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4.6 Stability against Earthquake/Check for liquefactions The sand layer below the upper clay layer consists of fine and poorly graded (sp) sand. Sand of such composition is susceptible to liquefaction. Liquefaction is a phenomenon similar to flow sides, but usually it is related to shock, especially due to Earthquake.
The project location is situated at zone‐ 2 of Bangladesh Earthquake zone map where in 0.15 is recommended by BNBC as factor for maximum horizontal ground acceleration.
The liquefaction potential as estimated following Seed and Idriss method is found to be generally negligible or none (i.e. F=R/L ≥1). Sample calculation for estimating the factor ‘F’ is provided as annexure in this report. The simplified method using embankment over burden stress, material composition including average size of particle (D50), percentage of fines (f.c) and standard penetration test value 'N' etc. demonstrates that there is practically little risk of liquefaction under normal circumstances. However, risks cannot be ignored, particularly in cases of localized lenses of mica. With available data/test results, these locations cannot be identified specifically at this stage of study. Equations and sample calculation is presented in Appendix‐1
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5 Riverbank Stability
5.1 Data and calculation method 5.1.1 Slope angles and Soil characteristics Analysis of the Jamuna Cross Sections shows, that the river in the project area is very shallow with a maximal depth of approx. 18 m.
The angle of the existing riverbank reaches from 1:5 (11.31°) to 1:1 (45°). The cross sections are shown in Figure 5‐1. It shows that the most slopes have an angle of 1:2 or flatter. Considering slopes flatter than 1:3 as safe, the calculation will concentrate on the slopes with an angle from 1:2, 1:2.5 or 1:3.
Figure 5‐1: Profile of the cross sections at the Jamuna River right bank
Figure 5‐2: Profile of the cross sections at the Jamuna River left bank Figure 5‐1 and Figure 5‐2 show the profiles of the cross sections at the Jamuna River at the left and right bank. The exact location of the Boreholes and the corresponding cross sections is shown in . The profiles of the cross sections and the location of the boreholes rin othe areas are similar.
The soil strata were determined by boreholes near the riverbank. The analysis of these boreholes show that the first upper soil layer in most cases is clay. Under this clay, the subsoil consists of sand in different densities, but mostly loose.
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The thickness of the first layer (clay) ranges from 2 m to 7 m with an average of 5 m. In some cases, when the deposit is recent, the sand is not covered by clay. This leads to four different types of soil distributions:
1. First layer Clay 2m, sand underneath 2. First layer clay 5m, sand underneath 3. First layer clay 7m, sand underneath 4. No clay, complete soil consists of sand
For these soils, following properties were considered: Soil 1 Sand: γ = 18 kN/m3 Soil 2 Clay: γ = 18 kN/m3 3 3 γW = 10kN/m γW = 10kN/m φ = 30° φ = 0 c = 0 c = 25 kN/m3
5.1.2 Calculation method For the calculation of the safety factor in case of an earthquake, a coefficient of 1.5% g in horizontal and vertical direction was considered. This equals an acceleration of 0.15 m/s² and is based on the Bangladesh National Building Code (BNBC).
In addition, in the calculations an earthquake coefficient of 5%g is considered. This consideration is based on Herbert Fedinger’s Report (Fedinger, 2006) and on the paper of Md. Hossain Ali (Hossain, 1998). The coefficient equals an acceleration of 0.5 m/s² in horizontal and vertical direction. This correlates to an earthquake with a return period of 200 years, which has a 10% probability of exceeding in 50 years lifespan of a structure.
These additional calculations were performed, because although the Bangladesh National Building Code (BNBC) implies, to use an earthquake coefficient of 1.5%, the report of Herbert Fedinger (2006) uses a higher coefficient in PIRDP.
All calculations were performed with the software Visual Slope, developed by Visual Slope, Loveland, Ohio, USA. The software uses the modified bishop method and for the type of failure, a circular failure was assumed. For each case, three hundred failure surfaces were calculated, to find the most critical one.
In the calculations, two different scenarios were considered. In the first one, the existing river bank slope is analyzed, in the second one the final, designed one. In both scenarios, the most critical slip circle was assumed to be located in the upper 9 m. This 9 m will be the steepest part of the final river bank and, in addition every possible soil change will be located in this area.
2,500 2,000 2,000 2 m Clay 1,500 2 m Clay 1,500 5 m Clay 5 m Clay 1,000 1,000 7 m Clay 7 m Clay 500 500 Sand only Sand only 0 0 1:2 1:2.5 1:3 1:2 1:2.5 1:3
Figure 5‐3: Safety factor for 35m slopes Figure 5‐4: Safety factor for 15m slopes
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5.2 Calculated Scenarios 5.2.1 Existing Riverbank In the first scenario, the existing slopes of the river bank were analyzed, by considering three different, representative slope angles and four different, representative soil distributions. In each case, the angle of the slope does not change on the whole range of the slope. The slopes also consider deep cross sections.
This leads to two different depths of the riverbed and the water level. 1. 15 m water level, 19 m riverbed 2. 35 m water level, 39 m riverbed
This leads to 24 different cases, which include the extreme cases (minimum clay; sand only) as well as the average cases.
Figure 5‐5: Dimensions of existing slopes
The results of the calculations are found in Table 5‐1.
Table 5‐1: Results of the calculation for existing Slopes
No H HW S First Layer Factor of Safety Remarks [m] [m] Normal EQ (1.5% g) EQ (5% g) 1 19 15 1:2 2m Clay 1.171 1.130 1.026 Flat circle 2 19 15 1:2 5m Clay 1.457 1.412 1.319 Big circle, both layer 3 19 15 1:2 7m Clay 1.195 1.144 1.040 Big circle, both layer 4 19 15 1:2 Sand only 1.171 1.130 1.026 Flat circle 5 19 15 1:2.5 2m Clay 1.456 1.390 1.259 Flat circle 6 19 15 1:2.5 5m Clay 1.571 1.541 1.399 Big circle, both layer 7 19 15 1:2.5 7m Clay 1.189 1.155 1.079 Big circle, both layer 8 19 15 1:2.5 Sand only 1.470 1.404 1.271 Flat circle 9 19 15 1:3 2m Clay 1.737 1.653 1.479 Flat circle 10 19 15 1:3 5m Clay 1.635 1.570 1.433 Big circle, both layer 11 19 15 1:3 7m Clay 1.316 1.269 1.169 Big circle, both layer 12 19 15 1:3 Sand only 1.737 1.653 1.479 Flat circle 13 39 35 1:2 2m Clay 1.171 1.129 1.026 Flat circle 14 39 35 1:2 5m Clay 1.556 1.509 1.408 Big circle, both layer 15 39 35 1:2 7m Clay 1.456 1.417 1.334 Big circle, both layer 16 39 35 1:2 Sand only 1.171 1.129 1.026 Flat circle
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No H HW S First Layer Factor of Safety Remarks [m] [m] Normal EQ (1.5% g) EQ (5% g) 17 39 35 1:2.5 2m Clay 1.468 1.402 1.270 Flat circle 18 39 35 1:2.5 5m Clay 1.767 1.700 1.557 Big circle, both layer 19 39 35 1:2.5 7m Clay 1.670 1.611 1.484 Big circle, both layer 20 39 35 1:2.5 Sand only 1.456 1.390 1.259 Flat circle 21 39 35 1:3 2m Clay 2.011 1.915 1.713 Flat circle 22 39 35 1:3 5m Clay 1.976 1.894 1.695 Big circle, both layer 23 39 35 1:3 7m Clay 1.754 1.674 1.504 Big circle, both layer 24 39 35 1:3 Sand only 1.736 1.653 1.479 Flat circle
The results for existing river banks according to Table 5‐1 show, as expected, an increasing safety for flatter slopes. The Safety factors of both the 1:2.5 and 1:3 slopes are sufficient in both, normal and earthquake case. An exception is case number 7 (19m 1:2.5 7m clay). In this case the safety factor is below the minimum acceptable (normal and earthquake) limit, as it is below 1.2.
Figure 5‐6: Typical slip circles at an existing slope
The calculated failure mechanism shows, that the upper clay layer has nearly no effect, if it is just 2 m thick, for the critical surfaces and the safety factors are nearly the same as in case of no clay layer. For a slope angle of 1:2, the safety factor in most cases does not at is fy the minimum limit.
In these cases the combination of a 5m clay layer with sand underneath seems to be the ideal soil distribution.
The analysis of the different possible failure surfaces show that the upper clay layer has a stabilizing function on the entire slope, as long as the layer is thick enough. So the safety factor increases significantly, when the upper layer is 5 m clay, while a 2 m clay layer has no significant effect. If the clay layer is thick enough, the most critical failure surface shifts from near the surfacee of the slop to the inner part. Further analysis show that most of the critical failure surfaces (up to a safety factor of 1.4) lie near the surface of the slope. 5.2.2 Designed river bank For the second scenario, the proposed, designed river bank slopes were considered with 24 different, representative cases. These slopes also consider deep cross sections.
This leads to two different depths of the riverbed and the water level. 1. 5 m water level, 19 m riverbed 2. 35 m water level, 39 m riverbed
These slopes will not have the same angle everywhere and in addition, a berm will be built about 1.5 m below low water level.
Page 25 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
The slope angle in relation to the depth is shown in Table 5‐2 for case 1: 19m river bed and Table 5‐3 incase 2: 39m river bed:
Table 5‐2: Case 1‐ 19 m river bed Part Slope Angle Vertical distance from Horizontal distance from river bank river bank (toe) 1:2 1:2.5 1:3 5 10 12.5 15 2 m Berm 0 5 12 14.5 17 1:2 9 20 24.5 29 1:2.2 14 31 35.5 40 1:2.5 19 43.5 48 52.5
Table 5‐3: Case 2‐ 39 m river bed Part Slope Angle Vertical distance from Horizontal distance from river bank river bank 1:2 1:2.5 1:3 5 10 12.5 15 2 m Berm 0 5 12 14.5 17 1:2 9 20 24.5 29 1:2.2 24 53 57.5 62 1:2.5 39 90.5 95 99.5
Figure 5‐7: Slope dimensions of designed slopes
2 2 2 m Clay 2 m Clay 1.5 1.5 5 m Clay 1 5 m Clay 1
0.5 0.5
0 0 1:2 1:2.5 1:3 1:2 1:2.5 1:3
Figure 5‐8: Safety factor for 35m slopes Figure 5‐9: Safety factor for 15m slopes
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Table 5‐4: Results of calculation for designed slopes
No. H HW S First Layer Factor of Safety Remarks [m] [m] Normal EQ (1.5% g) EQ (5% g) 1 19 15 1:2 2m Clay 1.358 1.308 1.200 Flat circle under berm 2 19 15 1:2 5m Clay 1.725 1.670 1.546 Both layers crossed 3 19 15 1:2 7m Clay 1.379 1.342 1.258 Both layers crossed 4 19 15 1:2 Sand only 1.174 1.133 1.029 Flat circle at toe of upper slope 5 19 15 1:2.5 2m Clay 1.503 1.439 1.300 Flat circle under berm 6 19 15 1:2.5 5m Clay 1.638 1.579 1.453 Both layers crossed 7 19 15 1:2.5 7m Clay 1.455 1.405 1.301 Both layers crossed 8 19 15 1:2.5 Sand only 1.476 1.411 1.276 Flat circle at toe of upper slope 9 19 15 1:3 2m Clay 1.608 1.532 1.380 Flat circle under berm 10 19 15 1:3 5m Clay 1.707 1.633 1.478 Both layers crossed 11 19 15 1:3 7m Clay 1.462 1.407 1.292 Both layers crossed 12 19 15 1:3 Sand only 1.608 1.532 1.380 Flat circle at toe of upper slope 13 39 35 1:2 2m Clay 1.216 1.173 1.068 Flat circle under berm 14 39 35 1:2 5m Clay 1.748 1.689 1.563 Both layers crossed 15 39 35 1:2 7m Clay 1.635 1.583 1.462 Both layers crossed 16 39 35 1:2 Sand only 1.206 1.064 1.059 Flat circle at toe of upper slope 17 39 35 1:2.5 2m Clay 1.479 1.415 1.282 Flat circle under berm 18 39 35 1:2.5 5m Clay 1.813 1.747 1.602 Both layers crossed 19 39 35 1:2.5 7m Clay 1.759 1.694 1.555 Both layers crossed 20 39 35 1:2.5 Sand only 1.478 1.414 1.278 Flat circle at toe of upper slope 21 39 35 1:3 2m Clay 1.608 1.532 1.380 Flat circle under berm 22 39 35 1:3 5m Clay 1.795 1.718 1.540 Both layers crossed 23 39 35 1:3 7m Clay 1.892 1.817 1.658 Both layers crossed 24 39 35 1:3 Sand only 1.608 1.532 1.380 Flat circle at toe of upper slope
The results for the calculation of the designed slopes, as shown in Table 5‐4 show, that the safety factors of the slopes with an angle of 1:2.5 or 1:3 are sufficient in every case (soil combination, earthquakes). The slopes with an angle of 1:2 also appear to be stable, gas lon as the upper layer (clay) is big enough.
The results also show that the clay layer only has a supporting function, if it is thick enough. In the case of a clay layer of just 2m, the failure surface and the safety factor are nearly the same as in the case of no clay layer.
Figure 5‐10: Typical slip circles at a designed slope
Page 27 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
5.3 Summary and Conclusion The results for both scenarios show, that the soil combination is as important as the slope angle. In nearly all cases a slope angle of 1:2.5 or flatter is sufficient, while in case of an angle of 1:2, stability is only guaranteed, if the clay layer is big enough (about 5.0 m thick).
The comparison of the both scenarios show, that the designed slopes are an improvement to the existing slopes. On the one hand, this results from the berm, which has a supporting effect, and on the other hand, it results from the different angles of the slope.
The results show, that the calculated earthquakes have a very small effect on the safety factor. This is due to the very small coefficient of just 1.5%. Although this is in accordance with the Bangladesh National Building Code, the coefficient is so small, that the effect can be disregarded. In addition, Herbert Fedinger used in his study in 2006 a coefficient of 5%, so the calculations may need tobe should be adjusted.
In addition, the berm could be extended, for it has on the one side a supporting function, which leads to a higher safety of the entire slope. The calculated failure surfaces also show that the berm limits the slip circle in case of a slope of sand only.
Page 28 September 2013 F1 Geotechnical Investigations
6 Summery RBP
6.1 General Geotechnical features The general feature of the sub‐soil formation consists of a total terrain with formation consist of a flat terrain with an upper layer of clayey silt and silty clay with fine sand and trace mica underlying by fine sand up to the depth of about 40 m from the existing ground surface. The clay‐silt layer (mainly CL‐ML group) varies from 2m to 7m in general whereas in some locations clay layer was not encountered. The consistencies of cohesive layers are medium to stiff which is soft at upper sections. The non‐cohesive sand layer is found to be very fine to fine sand with density increasing from loose to very dense with increase in depth.
6.2 Flood embankment stability From this analysis and past experience of previous studies, under normal conditions embankment slope between 1:2.5 to 1:3 appears to be adequate.
Average embankment height considered is 5.00m from ground level. A typical section of the proposed embankment is shown in Figure 1‐1 (a&b) for two conditions (with and without shelter provisions). Considering availability of embankment material, it is proposed to use dredged material from the river bed. The dredge materials appear to be permeable and hence susceptible to seepage.
Clay cladding of minimum 60 cm thick (as shown in Figure 1‐1 (a&b)) all around the embankment is recommended.
For facilitating the seepage flow and consolidation settlement this following measure as suggested:
(a) The base width of the embankment should be at least 35 m. (b) Provision of the compacted sand (60cm‐100cm) fills underneath the embankment by removing the existing top soil. (c) In order to compensate for settlement stage construction of embankment is recommended. A minimum of 2/3 stages may be required, each stage compacted height should be 2 ‐ 2.5m. Consolidation time that is interval between each stage should be 35 to 50 days. (d) Embankment material shall be free from all grass roots or organic material. The dredge fill shall have clay‐silt with very fine sand which have a plasticity index of 10‐20% in according with AASHTO (e) Method of construction: The materials should be spread in layers not exceeding 200mm loose and compacted to a density complying with 95% modified proctor. The edges with clay cladding should be constructed using benching method for each layer.
6.3 Riverbank Protection The results of the calculations show that the angle and the soil distribution are equally important. ‐ A slope angle of 1:2.5 or flatter is sufficient in every case ‐ A thick upper clay layer has a stabilizing effect on the slope, a slope with a clay layer of 5m or more is stable even for an angle of 1:2 ‐ The berm has a stabilizing effect on the slope
The calculation also considered the effects of earthquakes on the slope stability. The results show that 5% acceleration, in both vertical and horizontal direction, significantly decreases the safety factor. The safety factors of the designed slopes are still high enough, as long as the slope angle is 1:2.5 or flatter.
Figure 6.1 shows the comparison of a designed slope to an existing river profile.
Page 29 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
Figure 6‐1: Comparison designed slope to existing river profile
7 References 1. ADB (2002), Jamuna‐Meghna River Erosion Mitigation Project (JMREMP). 2. ADB (2010), Assam Integrated Flood and Riverbank Erosion Risk Management Investment Project (AIFRERMIP). 3. Fedinger, H. (2006), JMREMP Part‐B, Special Report, Geotechnical Report. 4. Hossain, M. A. (1998). Earthquake Database and seismic zoning of Bangladesh. Dhaka: Department of Civil Engineering, BUET. 5. Bangladesh National Building Code (BNBC). 6. Terzagh, Peck & Mesre. 7. Soil Mechanics in Engineering Practice, 3rd Edition‐1995. 8. SOFTWARE: VISUAL SLOPE, LOVE LAW, OHIO, USA. 9. RHD Standard Road Specification.
Page 30 September 2013 F1 Geotechnical Investigations
Appendices
Appendix 1: Sample Calculations ...... 32 Appendix 2: Corrected N’ Values for 4 Locations ...... 34 Appendix 3: Standard Penetration Test ...... 38
Page 31 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
Appendix 1: Sample Calculations
Check for liquefaction: As discussed earlier, project site is located in zone2 according to National Seismic Zone map, referred to in the BNBC. Accordingly maximum possible horizontal ground acceleration co‐efficient 0.15 is used in the study.
The method used for assessment of liquefaction potential consists of soil resulting from earth quake ground acceleration and comparing it with the cycle resistance ratio(R). The liquefaction resistance is defined as . The soil is likely to liquefy if the value of ratio is less than unity(one). The method is popularly known as Seed Method ( Ref. seed &Idris, 1971 and Iwasaki &Tatsuka 1978)
The following Equations are used determination of When, 0.65 ´ 0.0882 0.7
0.19 0.02 0.05 . 0.225 0.05 0.06 0.05 0.6 2.0
0 0% 40% 0.004 . 0.16 40% 100% 1.0 0.015 ´
ɣ Stress reduction coefficient Maximum horizontal ground acceleration Average grain size Liquefaction Resistance ratio Cyclic resistance ratio Cyclic stress ratio Standard Penetration test Depth of soil element . . Fine particle content passing 200 seive ´
In most cases it was found that there is no possibility of liquefaction of the underneath the embankment. Although few location appear to show factor of safety either 1 or marginally less than one 0.95 .
Page 32 September 2013 F1 Geotechnical Investigations
SAMPLE CALCULATION FOR CHECK AGAINEST LIQUIFACTION FOR JB‐1
For layer A
1.0 0.015 7 0.895 0.15 2.25
4 0.0882 0.0703 .8 7 0.7 . . 0.225 0.254 0.484 0.004 80 0.16 0.16 2.2 1
Assume total clay layer table 7.5m
84%, 10, 0.026 1.0 0.015 3.75 0.854 25%, 15 0.1 0.65 0.15 2.25 0.854 0.187 21.9 18 0.0882 0.0957 .8 9.75 0.7 . . 0.225 0.25
0.004 84 0.16 0.176 0.52 2.38 1
For layer B 1.0 0.5 9 0.865 0.65 0.15 2.25 0.865 0.189 0219 15 0.0882 0.096 .8 15 0.7 . . 0.225 0.122 0 0.218 0.219 1
Page 33 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
Appendix 2: Corrected N’ Values for 4 Locations Table A2.1: Corrected N’ Values (Koizuri‐Hurasagar Section)
KH-1 KH-2 KH-3 KH-4 KH-5 KH-6 KH-7 KH-8 KH-9 KH-10 KH-11 KH-12 KH-13 KH-14 KH-15
´ ´ ´ ´ ´ ´ ´ ´ ´ ´ ´ ´ ´ ´ ´ Depth Conversion Factor 1.5 1.5 15 18 15 18 1 2 12 15 5 6 3 4 6 7 3 4 5 6 5 6 3 4 2 3 3 4 3 4 2 3 3. 1.5 19 23 18 22 6 7 15 18 4 5 5 6 8 10 4 5 8 10 9 11 6 7 3 4 4 5 7 9 3 4 4.5 1.44 21 26 19 23 5 6 18 22 7 9 7 9 10 12 10 12 18 22 10 12 8 10 4 5 4 5 2 3 3 4 6 1.25 19 23 21 26 6 7 19 23 22 27 14 17 15 18 18 22 28 35 12 15 13 16 12 15 4 5 5 6 9 11 7.5 1.12 18 20 24 27 6 7 22 24 24 27 18 20 14 15 19 22 30 34 18 20 13 14 17 19 3 3 4 5 16 18 9 1.02 40 41 27 27 24 24 23 23 26 26 20 20 16 16 28 29 29 29 18 18 16 16 24 24 11 11 12 12 20 20 10.5 0.945 41 39 31 29 25 24 24 23 27 26 22 21 20 19 30 28 23 22 19 18 16 15 22 21 12 11 15 14 22 21 12 1.105 38 42 34 37 27 30 23 25 27 30 24 26 21 23 40 44 27 30 21 23 18 20 25 27 18 20 17 19 24 26 13.5 1.04 40 41 34 35 27 28 25 26 21 22 26 27 23 24 50 52 29 30 23 24 18 19 25 26 22 23 18 19 24 25 15 0.988 41 41 41 40 29 28 24 24 23 23 28 27 25 24 52 51 30 30 24 24 20 20 29 29 22 22 19 19 26 26 16.5 0.942 42 40 43 40 34 32 26 24 25 24 31 29 27 24 55 52 31 29 27 25 20 19 31 29 25 23 21 20 27 25 18 0.912 43 39 46 40 40 36 31 28 26 24 35 31 31 24 54 49 35 32 29 26 24 22 38 34 28 25 23 21 28 25 19.5 0.866 45 39 47 40 40 35 36 31 26 24 40 32 33 29 57 49 35 30 32 28 25 22 42 36 30 26 26 23 30 26 21 0.834 47 39 43 36 27 24 34 29 37 30 29 24 30 26 29 24 34 28 22.5 24 25.5 27 28.5 30 N=Field Value
Table A2.1: (continued) Corrected N’ Values (Koizuri‐Hurasagar Section)
KH-16 KH-17 KH-18 KH-19 KH-20 KH-21 KH-22 KH-23 KH-24 KH-25 KH-26 KH-27 KH-28 KH-29 KH-30
´ ´ ´ ´ ´ ´ ´ ´ ´ ´ ´ ´ ´ ´ ´ Depth Depth Conversion Factor 1.5 1.5 8 10 4 5 4 5 4 5 4 5 3 4 4 5 3 4 3 4 5 6 3 4 2 3 2 3 02 3 4 5 3 1.5 6 7 6 7 4 5 3 4 4 5 3 4 6 7 4 5 5 6 12 15 12 15 7 9 6 7 5 6 4 5 4.5 1.44 13 16 9 11 7 9 5 6 5 6 7 9 12 15 5 6 7 9 18 22 14 17 10 12 7 9 7 9 8 10 6 1.25 18 22 18 22 12 15 7 9 21 26 12 15 26 32 15 18 12 15 18 22 18 22 14 17 9 11 6 7 12 15 7.5 1.12 13 14 18 20 13 15 16 18 22 25 15 17 28 31 18 20 14 16 21 23 18 20 18 20 12 13 8 9 14 16 9 1.02 8 8 18 18 16 16 18 18 23 23 18 18 29 30 20 20 16 17 22 22 22 22 21 21 15 15 7 7 15 15 10.5 0.945 15 14 21 20 16 15 21 20 24 23 23 22 29 27 22 21 18 18 25 24 24 23 23 22 18 17 10 9 18 17 12 1.105 18 20 25 27 18 20 23 25 26 28 24 26 30 33 24 26 21 23 29 32 26 28 26 28 22 24 12 13 25 27 13.5 1.04 23 24 25 26 25 26 26 27 29 30 27 28 31 32 26 28 24 25 31 32 30 31 29 30 23 24 15 16 30 31 15 0.988 25 25 27 26 27 26 27 27 30 30 29 29 34 34 29 29 25 25 33 33 34 34 32 32 26 26 17 17 34 34 16.5 0.942 25 24 28 26 33 31 30 29 31 29 34 32 37 35 33 32 26 24 38 36 36 34 34 32 28 26 21 20 38 36 18 0.912 27 25 30 27 36 33 31 28 34 31 35 32 42 38 35 32 29 26 42 38 40 36 36 33 30 27 24 22 41 37 19.5 0.866 28 24 33 28 40 34 32 28 41 36 33 28 45 39 36 31 36 31 46 40 42 36 38 33 36 31 28 24 48 41 21 0.834 35 29 36 30 38 33 37 31 48 40 38 32 32 27 22.5 24 25.5 27 28.5 30
Page 34 September 2013 F1 Geotechnical Investigations
Table A2.1: (continued) Corrected N’ Values (Koizuri‐Hurasagar Section)
KH-31 KH-32 KH-33 KH-34 KH-35 KH-36 KH-37 KH-38 KH-39 KH-40
´ ´ ´ ´ ´ ´ ´ ´ ´ ´ Depth Depth Conversion Factor 1.5 1.5 3 4 4 5 4 5 2 3 3 4 3 4 2 3 3 4 2 3 2 3 3 1.5 4 5 6 7 6 7 4 5 7 9 4 5 5 6 5 6 4 5 6 7 4.5 1.44 5 6 4 5 9 11 8 10 10 12 11 14 6 7 6 7 6 7 7 9 6 1.25 7 9 6 7 11 14 11 14 14 17 14 17 7 9 6 7 11 14 7.5 1.12 11 12 9 10 15 17 12 13 18 20 14 16 9 10 10 11 7 8 17 19 9 1.02 15 15 8 8 14 14 14 14 17 17 15 15 12 12 12 12 9 9 17 18 10.5 0.945 17 16 12 11 15 14 16 15 22 21 16 15 12 11 13 12 13 12 20 19 12 1.105 18 20 18 19 17 19 20 22 22 24 18 20 16 18 16 18 15 17 21 23 13.5 1.04 20 21 22 23 19 20 22 23 23 24 22 23 18 19 15 16 22 23 22 23 15 0.988 19 19 27 26 20 20 26 26 24 24 22 22 22 22 18 18 24 24 24 24 16.5 0.942 23 22 30 28 21 17 29 27 25 24 24 23 23 22 22 21 23 22 24 23 18 0.912 25 23 34 31 22 20 32 29 27 25 26 24 25 23 27 25 25 23 26 24 19.5 0.866 28 24 38 33 22 19 34 29 27 23 29 25 26 24 28 24 28 24 28 24 21 0.834 29 24 24 20 29 24 29 24 31 26 29 25 35 29 22.5 24 25.5 27 28.5 30
Page 35 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
Table A2.2: Corrected N’ Values (Chouhali ‐ Nagarpur Section)
CN-1 CN -2 CN -3 CN -4 CN -5 CN -6 CN -7 CN -8 CN -9 CN -10 CN -11 CN -12 CN -13 CN -14 CN -15
´ ´ ´ ´ ´ ´ ´ ´ ´ ´ ´ ´ ´ ´ ´ Depth Conversi on Factor 1.5 1.5 4 6 4 5 3 4 4 5 4 5 4 5 3 4 3 4 4 5 6 7 4 5 5 6 4 5 5 6 4 5 3 1.5 5 7 2 3 4 5 2 3 2 7 2 3 7 8 5 6 6 7 8 10 5 6 7 8 4 5 12 15 6 7 4.5 1.44 7 10 9 4 5 6 4 5 4 12 4 5 16 18 9 11 8 10 8 10 11 13 12 15 4 5 14 17 7 8 6 1.25 14 17 7 9 10 12 7 9 7 15 7 9 16 18 12 15 14 17 16 20 12 15 14 17 24 24 15 16 15 18 7.5 1.12 15 16 12 13 11 12 11 12 11 12 11 12 19 21 15 17 15 17 18 20 13 14 18 20 26 26 15 16 18 20 9 1.02 18 18 13 13 11 11 10 10 10 17 15 15 20 20 17 17 18 18 50 20 14 14 18 18 26 26 17 17 19 19 10.5 0.945 20 20 16 15 13 12 13 13 13 20 17 17 20 20 20 20 20 19 24 22 15 14 22 20 27 26 18 18 19 18 12 1.105 20 22 17 19 15 16 13 14 13 22 17 19 22 22 21 23 22 24 24 25 16 18 26 27 27 29 19 21 22 24 13.5 1.04 23 22 18 19 16 16 15 15 15 23 18 18 22 22 25 26 23 24 26 26 15 18 26 27 29 29 21 22 22 23 15 0.988 23 23 22 22 17 17 15 15 15 24 20 20 22 20 25 25 26 25 26 26 21 18 29 28 29 29 22 22 22 22 16.5 0.942 24 23 24 23 22 20 15 15 15 24 20 20 26 24 26 24 26 24 28 25 23 18 29 28 31 29 24 22 24 23 18 0.912 26 25 24 22 22 20 18 17 18 23 20 18 26 23 27 25 29 26 29 26 25 26 31 28 31 32 25 26 24 22 19.5 0.866 27 24 28 25 25 22 19 17 19 23 21 19 26 23 27 22 31 28 34 30 26 26 32 29 33 32 28 26 25 22 21 0.834 29 26 28 25 26 23 18 18 18 25 22 20 28 25 29 26 31 28 36 32 27 26 32 29 34 32 29 26 28 24 22.5 30 27 37 31 42 30 30 27 28 33 37 32 32 30 29 24 24 25.5 27 28.5 30
Table A2.2: (continued) Corrected N’ Values (Chouhali ‐ Nagarpur Section)
CN-16 CN -17 CN -18 CN-19
´ ´ ´ ´ Depth Conversion Factor 1.5 1.5 4 5 2 3 2 3 3 4 3 1.5 4 5 4 5 4 5 4 5 4.5 1.44 9 11 6 7 6 7 8 10 6 1.25 14 17 8 10 9 11 10 13 7.5 1.12 15 17 14 16 16 18 16 18 9 1.02 18 18 16 16 23 23 18 18 10.5 0.945 21 20 22 21 18 17 18 17 12 1.105 23 25 22 24 18 20 22 24 13.5 1.04 25 25 24 25 20 21 22 23 15 0.988 26 28 24 24 20 20 26 26 16.5 0.942 30 28 29 27 25 24 26 24 18 0.912 30 27 29 26 25 24 28 24 19.5 0.866 32 27 31 27 28 24 28 24 21 0.834 32 27 32 27 31 26 28 24 22.5 24 25.5 35 29 36 30 34 30 30 25 27 28.5 30
Page 36 September 2013 F1 Geotechnical Investigations
Table A2.3: Corrected N’ Values (Enayetpur – Koizuri Section)
v EK-1 EK-2 EK-3 EK-4 EK-5 EK-6 EK-7 EK-8 EK-9 EK-10 EK-11 EK-12 EK-13 EK-14 ´ ´ ´ ´ ´ ´ ´ ´ ´ ´ ´ ´ ´ ´ Depth Con ersion Facto 1.5 1.5 2 3 3 4 3 4 5 6 3 4 4 5 3 4 6 7 5 6 7 9 5 6 5 6 5 6 4 5 3 1.5 4 5 4 5 4 5 6 7 5 6 5 6 5 6 8 10 7 9 12 15 6 7 7 9 5 6 5 6 4.5 1.44 10 12 7 9 5 6 8 10 6 7 7 9 8 10 11 14 11 14 13 16 9 11 12 15 10 12 10 12 6 1.25 18 22 15 18 5 6 15 18 15 18 9 11 12 15 12 15 15 18 15 18 14 17 15 18 15 18 12 15 7.5 1.12 22 24 18 20 15 17 18 20 18 20 14 15 15 17 15 14 16 18 17 19 18 20 17 19 18 20 15 17 9 1.02 22 22 20 20 17 17 19 19 21 21 15 15 18 18 19 19 18 18 20 20 22 22 22 22 22 22 17 17 10.5 0.945 24 22 21 20 20 19 21 20 24 23 18 17 18 17 25 24 21 20 23 22 24 23 24 23 26 24 19 18 12 1.105 24 26 23 25 24 26 22 24 27 30 22 24 20 22 29 32 24 26 26 28 25 27 26 28 30 33 21 23 13.5 1.04 26 27 23 24 25 26 23 24 31 32 24 25 20 21 30 31 28 29 29 30 26 27 30 31 30 31 25 26 15 0.988 26 26 26 25 26 26 23 23 34 32 27 27 20 20 32 32 31 30 34 34 30 29 32 32 32 31 27 26 16.5 0.942 28 26 27 25 27 26 27 26 36 34 29 27 22 20 35 33 35 32 37 35 30 28 37 35 32 31 32 30 18 0.912 29 25 28 25 28 26 27 26 29 34 30 27 24 20 38 33 38 35 38 35 32 29 42 38 33 31 34 31 19.5 0.866 30 26 28 24 29 25 27 26 40 35 31 27 24 20 42 35 40 35 40 35 34 29 41 35 34 31 36 31 21 0.834 31 26 29 24 29 25 29 26 46 35 32 27 26 21 46 36 42 35 43 35 38 29 42 35 35 30 38 32 22.5 24 25.5 27 28.5 30
Table A2.4: Corrected N’ Values (Jafargonj – Bachamara Section)
JB-1 JB-2 JB-3 JB-4 JB-5 JB-6 JB-7 JB-8 JB-9 JB-10
´ ´ ´ ´ ´ ´ ´ ´ ´ ´ Depth Conversion Factor 1.5 1.5 4 5 8 10 2 3 4 5 5 6 6 6 7 5 6 4 5 5 6 3 1.5 2 3 12 15 2 5 2 3 10 12 8 12 15 7 9 2 3 10 12 4.5 1.44 3 4 13 16 4 3 4 5 13 15 15 14 17 8 10 9 11 14 17 6 1.25 5 6 15 19 6 7 14 17 17 16 20 13 16 13 16 7 9 7.5 1.12 19 21 17 19 3 4 12 13 15 17 22 18 20 14 16 13 15 8 9 9 1.02 24 24 16 16 3 4 15 15 22 22 25 21 21 16 16 15 15 13 13 10.5 0.945 10 9 20 19 4 4 17 16 24 23 27 22 21 18 17 18 17 14 13 12 1.105 24 26 7 8 17 18 26 29 27 26 28 22 24 24 26 22 24 13.5 1.04 27 28 26 27 15 16 20 21 28 29 27 26 26 22 23 30 31 25 26 15 0.988 31 31 29 29 22 22 18 18 30 30 29 26 26 26 26 34 34 29 29 16.5 0.942 33 22 30 28 28 26 22 21 32 30 296 29 27 27 25 38 36 29 27 18 0.912 34 31 31 28 28 25 23 21 34 31 30 30 27 30 27 40 36 29 26 19.5 0.866 34 32 32 28 33 28 24 21 36 31 31 31 26 32 28 42 34 32 28 21 0.834 37 33 33 287 34 28 27 22 38 33 32 32 26 36 30 48 40 34 28 22.5 24 25.5 27 28.5 30
Page 37 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
Appendix 3: Standard Penetration Test
As indicated earlier Standard penetration test (SPT) were carried out at an interval of 1.5 m. for the full depth of exploration of each bore hole.
The SPT field values are in number of blows/ 300mm penetration. The field results are affected by over burden stress, energy losses, non‐standard equipment and operators. In order to take this into consideration for assessments of liquefaction and stability analysis, corrected version of N‐values is used. The method of N value correction is in accordance with that described in bowels (1996) in the present report; corrected value has been evaluated using the following equation:
1.14 , , 1 96.76 .
The N‐ Value corrected values are estimated accordingly to the above equation. The values N’ are presented as annexure in table.
Page 38 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 F2 Technical Designs for Tranche‐1 Work
September 2013
PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
Page 40 September 2013 Technical Designs for Tranch‐1 Work
Table of Content 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 1 Introduction and Background ...... 45 1.1 PPTA Outline ...... 45 1.2 Physical Environment ...... 45 1.3 Design Issues and Principles ...... 46 1.4 Locations of selected interventions ...... 47 1.4.1 The Priority Works under Tranche‐1 ...... 47 1.4.1.1 Jamuna Right Bank‐1 (JRB‐1) ...... 47 1.4.1.2 Jamuna Left Bank‐2 & Padma Left Bank‐1 (JLB‐2 & PLB‐1) ...... 48 1.5 Components under the Planned Program ...... 48 2 Embankments ...... 49 2.1 Embankment Location ...... 49 2.2 Subsoil Conditions ...... 49 2.2.1 General Soil Characteristics in Bangladesh ...... 49 2.2.2 Subsoil Investigations Conducted by BWDB ...... 49 2.2.3 Sub‐soil Profiles ...... 51 2.3 Stability Analysis for Embankments ...... 51 2.3.1 Outline of Analysis ...... 51 2.3.2 Assumptions for Embankment Material ...... 51 2.3.3 Results of Analysis ...... 52 2.3.4 Embankment Alignment and Cross Sections ...... 52 2.3.5 Crest level of Embankment ...... 54 2.3.6 Set Back ...... 55 2.3.7 New Embankment ...... 55 2.3.8 Re‐Sectioning of Embankment ...... 55
Page 41 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
2.3.9 Road over the embankment ...... 56 3 Drainage Provisions ...... 57 3.1 Drainage Channels/Khals ...... 57 3.2 Drainage Structures ...... 57 3.3 Design Criteria for Hydraulic Structures ...... 58 3.3.1 General ...... 58 3.3.2 Design Flood Frequency ...... 58 3.3.3 Crest level of Structure ...... 59 3.3.4 Design of hydraulic structures (Drainage cum flushing Regulator) ...... 59 3.3.5 Setting out Invert Level of Structure ...... 59 3.3.6 Hydrological Design ...... 59 3.3.7 Fixation of Vent Size and Design Discharge ...... 60 3.3.8 Drainage capacity of regulators ...... 61 3.3.9 Hydraulic Design ...... 62 3.3.10 Energy dissipation arrangement ...... 63 3.3.11 Structural Design ...... 64 4 Riverbank Protection Works ...... 65 4.1 Proposed Works ...... 65 4.2 Hydrological Observations ...... 65 4.3 Data for Bank/Slope Protection ...... 66 4.4 Elements of Slope Protection ...... 67 4.5 Design Discharges ...... 67 4.5.1 Total River Discharges and Number of Channels ...... 67 4.5.2 Flow Distribution in anabranches ...... 68 4.6 Design Water Level ...... 69 4.7 Flow Velocity ...... 69 4.7.1 Requirements ...... 69 4.7.2 Brahmaputra‐Jamuna River ...... 70 4.7.3 Padma River ...... 70 4.8 Size of bed material ...... 71 4.8.1 Bed material for Brahmaputra‐Jamuna ...... 71 4.8.1.1 Scour at Brahmaputra‐Jamuna ...... 71 4.8.2 Bed material for Padma ...... 72 4.8.2.1 Scour at Harirampur ...... 72 4.9 Waves ...... 72 4.10 Design Cross Section ...... 72 4.11 Selection of Type of Bank Protection ...... 73 4.12 Size and thickness of protection element: ...... 73 4.13 Size of Elements for Bank Protection ...... 74 4.13.1 Slope Protection above av.LWL: ...... 74 4.13.2 Under Water Slope Protection: ...... 74 4.13.3 Launching Apron: ...... 74 5 Estimate ...... 75 6 Alternate Approach for Protection ...... 76 1 Design Criteria ...... 133 1.1 Design Life ...... 133 1.2 Standards and Design Guidelines ...... 313 1.3 General Approach ...... 134 1.4 Hydrology and Hydraulic Parameters ...... 134 1.4.1 River Discharge and Flood Level ...... 134 1.4.2 Flow velocity ...... 136 1.4.3 Wind‐Generated Waves ...... 136 1.4.4 Freeboard ...... 138 1.5 Scour ...... 138
Page 42 September 2013 Technical Designs for Tranch‐1 Work
1.6 Design of Erosion Protection Counter‐Measures ...... 138 1.6.1 Slope Protection – River Currents ...... 138 1.6.2 Scour Protection Apron ...... 138 1.6.3 Erosion Protection Waves ...... 139 1.7 Slope Stability...... 139 2 Drainage and Flushing Structures ...... 140 2.1 Draining Capacity ...... 140 2.2 Hydraulic and Structural Details ...... 140 1. General ...... 143 2. Generation of Waves: ...... 146 3. Transition zone (Shoaling and Refraction) ...... 152 4. Wind Conditions in Bangladesh ...... 153 4.1 General ...... 153 4.2 Previous Studies ...... 153 4.3 JMREMP Study ...... 154 5. Waves on Rivers ...... 165 6. Waves at PIRDP and IPMD ...... 166
Appendices
Appendix I: Sample Design Calculation for Bank Protection Works at Chouhali ...... 78 Appendix II: Sample Design Calculation for Regulator at Gala (4V‐ 1.5m x 1.8m) ...... 93 Appendix III: The Preliminary Estimates for Tranch‐1, Tranch‐2 and Tranch‐3 ...... 122 Appendix IV: Design Criteria ...... 131 Appendix V: Road on the Land‐Side of Rehabilitated or Reconstructed Embankment ...... 172 Appendix VI: Comment Matrix ...... 198 (In Separate Volume).
Page 43 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
Tables
Table 3‐1: Provides key design considerations for this feasibility level study: ...... 58 Table 3‐2: Conditions of flow ...... 60 Table 4‐1: Bankfull Discharge of Major Rivers ...... 67 Table 4‐2: The Simulated flow distribution along anabranches of the Jamuna under hydrological condition (a) & (b) ...... 68 Table 4‐3: Measured Velocity in Bahadurabad, Jamuna ...... 70 Table 4‐4: Limits of Standard Bank Protection Structures ...... 70 Table 4‐5: Empirical multiplying factors for maximum scour depth...... 71 Table 4‐7 Quantities adopted for the design ...... 75 Table 4-1: Wind speed and direction reported by Halcrow (1994)4: ...... 153 Table 4-2: Average Wind Speed from 1996-2005 ...... 155 Table 6-1: Wave height calculation for several wind speeds and fetch length ...... 166 Table 6-2: Wave estimation for PIRDP site ...... 168 Table 6-3: Wave estimation for MDIP site ...... 170
Figures Figure 2‐1 Location of BWDB boreholes ...... 50 Figure 2‐2: Embankment section with and without Temp Settlement area...... 54 Figure 2‐3 Long section of embankment alignment showing the 100 yr. HWL and embankment crest level ...... 54 Figure 3‐1 Showing the location of all proposed regulators under Tranch‐1 (JRB‐1) ...... 62 Figure 3‐2 Long section of Regulator showing water levels in R/S and C/S ...... 63 Figure 3‐3 Long section of Regulator showing basin and flexible protection at end ...... 64 Figure 4‐1 Showing Locations of Bank Protection Works under Tranch‐1 ...... 65 Figure 4‐2 Envelope cure of measured cross‐sections ...... 73
Page 44 September 2013 Technical Designs for Tranch‐1 Work
1 Introduction and Background
1.1 PPTA Outline The Asian Development Bank (ADB) is undertaking a feasibility assessment of a flood and riverbank erosion risk management program covering parts of the main rivers of Bangladesh, funded by the Japan Fund for Poverty Reduction (JFPR). The objective of the Main River Flood and Bank Erosion Risk Management Program (MRP) is to reduce the riverbank erosion and flood risks to the adjacent flood plains while maximizing economic activities in a sustainable and environmentally acceptable manner. Existing flood embankments dominantly fail from riverbank erosion, and as such the stabilization of the river pattern is a cornerstone of reducing the flood risk. The MRP builds on and extends the activities of the Jamuna‐Meghna River Erosion Mitigation Project (JMREMP) (ADB, 2002), implemented in different phases from January 2003 until June 2011. In addition, a similar project, the Assam Integrated Flood and Riverbank Erosion Risk Management Investment Project (AIFRERMIP) (ADB, 2010) provides important insight into a number of relevant project elements and processes especially integrating disaster risk management measures related to the flood and riverbank erosion risk under the dictate of the Integrated Water Resources Management (IWRM) framework.
1.2 Physical Environment The topography of Bangladesh is mainly comprised of the fertile alluvial floodplains of three large rivers namely Ganges, Brahmaputra and Meghna with over 92% of their catchments situated outside the country. These three rivers combine within the country to form the Lower Meghna, which drains into the Bay of Bengal via a constantly changing network of estuaries, tidal creeks and active deltaic coastline of the Bay. More than fifty other mid‐sized rivers also flow through Bangladesh and drain into the Bay of Bengal. Out of this river network the planned program envisages to cover the main rivers from Jamuna Bridge to Chandpur.
Past efforts to mitigate flood damages by building flood embankments along some of the main rivers had limited success. A major contributing factor to failure was the ongoing channel instability and river bank erosion that caused embankments to fail by breaching or required the embankments be retired. Brahmaputra Right Flood Embankment (BRE) built in late 1960s for a length of about 217 km (from Kaunia, Rangpur to Bherakhola, Pabna) needed retirement for about 70 km in different places. Even at present about 16.00 km of embankment is still open. Existing flood embankments failed due to riverbank erosion, and as such the stabilization of the river pattern is a cornerstone for reducing the flood risk. To add stability to the embankment an integrated approach, involving channel stabilization and flood mitigation, is required.
Riverbank erosion is one of the major natural disasters in Bangladesh causing untold miseries every year to thousands of people living along the banks of major rivers of Bangladesh. Bank erosion has rendered millions homeless and is a major social hazard. In 2011, the Brahmaputra‐Jamuna, the Ganges and the Padma eroded about 3600 ha of land, 400 ha of settlement, 2240 m of active flood embankment, 2070 m of district road, 115m m of upazila road and 4320 m of rural road (CEGIS, April 2012). Only along Jamuna about 2000 ha of land was eroded in 2011. Brahmaputra Right Embankment, originally built to provide flood control to 117,400 ha during the period 1963‐64 to 1967‐68 has failed to serve the intended goal due to erosion.
The need of river training and bank protection in Bangladesh arises from the fact that most rivers of the country are unstable, i.e. they are not in a state of equilibrium with the governing physical processes. Both, river training and bank protection measures have the objective to ensure a safe and efficient transport of water and sediments through a certain defined stretch of the river.
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In order to prevent or minimize the loss of valuable land, several stretches of the river banks might need suitable protection against erosion. In this context it has to be emphasized, that in case of planning local protection measures, the consequences must be taken into account, against a certain response of eth river, i.e. morphological changes in the vicinity or even further away from a countermeasure, are to be expected. Protection of one place will possibly influence erosion and bankline shifting at other locations. From that point of view, only absolutely necessary measures are considered.
In addition to loss of valuable land by erosion, the damages are caused to crops due to high flood depth and early flood in the lower flood plains, deposition of sand on the agricultural fields and sediment deposition on river route are the additional hazards due to erosion associated with flood.
1.3 Design Issues and Principles The project builds on and extends the activities of Jamuna‐Meghna River Erosion Mitigation Projects (JMREMP) (ADB, 2002), implemented from January 2003 to June 2011. In addition to taking account of the experiences from JMREMP, the project records the earlier efforts made by BWDB in controlling flood and takes account of experience gained under earlier and recent attempts for stabilizing the river and reducing the flood damages.
In the recent days flood damages are on the rise in Bangladesh due to increase in population density and increased infrastructure in vulnerable areas. It is observed that the reliable structural and non‐ structural measures reduces flood and erosion damages and retains benefit to the local population.
The experience gained under different projects through interventions on major rivers, documented in the Guidelines for River Bank Protection, 2010, also point to a vision to be chosen for stabilization of the river. Experience gained from different ongoing and past initiatives in this respect has also been and is being taken into consideration in formulating the design under this project.
BWDB, under JMREMP, has built 10.0 km of riverbank protection from Koizuri towards the Hurasagar River. JMREMP originally provided 7.0 km of protection along the bank of Brahmaputra‐Jamuna from Kaitala to Mohanpur. The executed bank protection along the two reaches has contributed to the stabilization of navigation channel towards Baghabari Port. Substantial reduction of the annual dredging volume for the channel access to the Baghabari Port may be due to the protection work executed under JMREMP.
The introduction of low cost and sustainable bank protection technology along with flood management applications in JMREMP (ADB, 2002) shall be the major tool for accruing benefit from the gift of nature i.e. the river.
The present project is intended to build on JMREMP designs, Guideline for Bank Protection, 2010 approved and lessons from Padma Bridge design.
Activities to date, have concentrated on arresting riverbank erosion along one bank, while future activities need to focus on river stabilization and consequently both banks at the same time. The systematic river stabilization provides Bangladesh also with the long cherished opportunity to regain some of the lost floodplain land, while at the same time providing additional natural zones to improve the stressed river habitats.
The PPTA consultant team assessed the vulnerability of each location along the major rivers and prioritized the work to be taken under the project. After collecting the data from the field the following criteria was prepared to rank the intervention for the priority investment program under tranch‐1. Embankment breach length and location
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Erosion length Existing rate of bank erosion Requirement of Bank Protection Work Location within a risk zone Drainage congestion area Flood area Opinion of stakeholder in terms of vulnerability Estimated Rehabilitation cost of each intervention
1.4 Locations of selected interventions The program will focus on the selected reaches of the main rivers‐Brahmaputra‐Jamuna, Ganges and Padma River. The primary focus of the program is riverbank erosion and flood risk management along the Jamuna River downstream of Bangabandhu (Jamuna) Bridge, Padma River from the Jamuna confluence to Upper Meghna confluence and eth Ganges River downstream of proposed Ganges Barrage. The data for the whole affected reaches (erosion, flood, sand casting etc.) were collected from primary and secondary sources. The activities under the project has been grouped under three tranches namely Tranch‐1, Tranch‐2 and Tranch‐3. Priority selection under tranch‐n1 has bee made on multi criteria analysis (MCA) conducted on all the problems identified on the whole reach.
1.4.1 The Priority Works under Tranche‐1 Right Bank of Brahmaputra‐Jamuna (JRB1) (i) Embankment from Koizuri to Hurasagar outfall (new): 12.50 km (ii) Embankment from Hurasagar outfall to Shahjadpur (rehabilitation): 16.50 km (iii) Bank protection near Hurasagar (Benotia) Outfall: 1.00 km
Left Bank of Brahmaputra‐Jamuna (JLB‐2) (iv) Bank Protection in Chouhali‐Nagarpur: 5.0 km (v) Bank Protection in Jafarganj‐Bachamara: 2.0 km
Left Bank of Padma (PLB‐1) (vi) Bank Protection in Harirampur area: 7.0 km
1.4.1.1 Jamuna Right Bank‐1 (JRB‐1) (right bank of Jamuna River downstream of Jamuna Bridge)
The Brahmaputra‐Jamuna flows as straight channel downstream of Jamuna Bridge for about 15 km along the left bank. As a consequence an about 15 km long and 5 km wide stable attached char has formed along the right bank. The channel bifurcates into a western and eastern branch near Enayetpur, the eastern one presently being dominant. This bifurcation appears to be stable.
The major area in the right bank downstream of Enayetpur was protected by the Brahmaputra Right Embankment (BRE), which has been eroded over a length of around 12 km at the downstream end. The breach has brought the once protected area back to the natural cycle of flooding, with substantial deposition of sand along the riverbanks.
In the study area the reach severely affected by flood and sand deposition is the zone from Koizuri to Hurasagar off take along Brahmaputra‐Jamuna River, where BRE is already eroded and the zone from Hurasagar off take to Shahjadpur along Hurasagar River, where the existing embankment is eroded in several reaches and in very bad shape in some other reaches. The embankment along Jamuna in this reach is to be reconstructed and the embankment along Hurasagar and Karotoa River need to be rehabilitated in some reaches and reconstructed in other reaches.
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The reconstruction and rehabilitation of the embankment along the area mentioned will lead to reconstruction of regulators already eroded and also meet the deficiency of drainage and flushing requirement felt during the project operation period.
A major portion of the bankline of this reach along Jamuna river is protected against bank erosion under JMREMP.
1.4.1.2 Jamuna Left Bank‐2 & Padma Left Bank‐1 (JLB‐2 & PLB‐1) (JLB2: left bank of Jamuna River downstream of Dhaleshwari offtake to Jamuna‐Ganges confluence; PLB1: left bank of Padma River just downstream of Jamuna‐Ganges confluence)
The other areas of interest are in the left bank of Brahmaputra‐Jamuna and left bank of Padma affected by erosion, flood and sand deposition. Bank protection in all these areas is given preference over flood management measures, which are planned to commence in Tranche‐2.
The remaining area affected by flood, sand deposition and erosion will likely be included under the project through studies conducted under different tranches and prioritization fixed through MCA.
1.5 Components under the Planned Program In general, the following works are involved in the project under tranche1:
Embankments: o Construction of embankment o Re‐sectioning of embankment o Repair of existing drainage structure (if repairable) o Replacement/Construction of drainage cum flushing regulators o Alternative drainage/flushing structures. Bank Protection and River Training works o Underwater works consisting of geobags o above water works (wave protection) consisting of concrete blocks/slabs o buoys for navigation purposes along the protected riverbanks and protection of fish
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2 Embankments
2.1 Embankment Location The embankment in the right bank of Brahmaputra‐Jamuna river from Koizuri to Hurasagar outfall will be reconstructed following a retired alignment. The embankment under Hurasagar sub‐project, from Bherakhola to Karotoa river also need to be rehabilitated and reconstructed as needed to serve the project requirement. The preliminary design of the embankment along Brahmaputra‐Jamuna is prepared to protect the area against flood with a free board of 1.5m on 100 year HF and that along Hurasagar is designed on 100 year HFL with 1.0m free board.
In designing the embankment emphasis on the impact of HWL as well as climate change scenario have been considered. During the design of embankments, due consideration on the causes of its failure has also been given.
2.2 Subsoil Conditions 2.2.1 General Soil Characteristics in Bangladesh Bangladesh consists primarily of deltaic alluvial sediments of the big rivers Ganges, Padma, Brahmaputra/ Jamuna, Meghna and their tributaries. The basins of the Brahmaputra/Jamuna and the Ganges are bounded to the tectonically highly active Himalayas mountain ranges, which are subject to severe erosion contributing to the heavy sediment load in the Ganges and the Brahmaputra/ Jamuna river. The entire country of Bangladesh is a part of the Bengal basin, filled in the tertiary quaternary geological period. The basin is an area of subsidence, which is balanced by the deposition of sediments supplied by its river system.
The floodplain of the main rivers consist of recently deposited sediments. The oscillation zone of these rivers consists of alluvial sand and is covered by alluvial silt or deltaic silt. In general, alluvial sediments ranges from fine silt to gravel, whereas a large part (about 60 to 85% of the total volume) of the sediment load in all rivers of Bangladesh consists of silty materials. The recent sediments near the present courses of the major rivers can physically be classified as: Alluvial sand, Alluvial silt, Alluvial silt and clay, Marsh and clay peat, Deltaic sand and Deltaic silt.
2.2.2 Subsoil Investigations Conducted by BWDB A soil exploration program was undertaken to investigate the sub soil condition at the selected project sites for Main River Flood and Bank Erosion Risk Management Program.
Accordingly, for the preliminary project formulation and feasibility study; a number of bore‐holes were explored through the Ground Water Hydrology Division of BWDB, during November 2011 to February 2012.
The locations of executed bore holes are (Figure 2‐1): At right bank of river Jamuna from Bherakhola to Baghabari port and Benotia Bazar to Bherakhola a total of 40BH designated as KH‐1 to KH‐40 in Sirajganj District. At right kban of Jamuna from Enayetpur to Koizuri, a total of 14 BH designated as EK‐1 to EK‐14 in Sirajganj District.
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At left bank of Jamuna in Chouhali‐Nagarpur, 19 BH designated as CN.1 to CN.19, in Tangail District At left Bank of Jamuna in Jafarganj ‐ Bachamara, a total of 10 BH designated as JB‐1 to JB‐10 under Manikganj District.
Figure 2‐1: Location of BWDB boreholes
Depth of Bore‐hole, locations with co‐ordinates and BH locations on satellite images are shown in Annex F1.
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2.2.3 Sub‐soil Profiles The general observation on soil strata is: The sub‐surface soil formation is a two layer system. In general in all four section, the upper layer consists of fine grained soil of low to inter‐mediate plasticity with few exceptions where in it is referred to as plastic, semi ‐plastic or even non‐ plastic (up‐to above RL+ 4 to+ 5m PWD). Broadly Classified as CL‐ML type soil The lower part (i.e. below + 4 to + 5m PWD) mainly consists of very fine to fine to medium grained sands up‐to depth of exploration. Very thin film of mica mineral in traces were also encountered at varying depths.
A generalized summary of drilling at the project locations show a upper clay‐silt or silt‐clay layers referred to in the this report as CL‐ML (often found to be CH‐MH) which consists of silt clay /t clayey sil with low to medium plasticity. Below the upper clayey layer fine grained and poorly graded sand, referred to as SP/SM or FS sometimes very fine sand, VFS of medium compactness. The sand strata has general trend of mild increase in density from medium to dense becoming very dense at depth around 30m and below. (As evident from BH Logs)
The observed slope inclination at river in sand is found to be 1:2.5‐1:3 for about 50% of the project area which is expected with limit equilibrium condition. The angle of internal friction, which is the shear strength of sand in these case are 28 ‐ 30 with very low effective cohesion estimated at c=2‐4 kpa.
2.3 Stability Analysis for Embankments 2.3.1 Outline of Analysis On the basis of the result of geotechnical investigation carried out by BWDB, some preliminary stability analysis was carried for the proposed flood protection embankment and bank slope. The slope protection and erosion control of the vulnerable river bank is not considered here and are addressed separately at a later stage. For the purpose of analysis the following assumptions are made: dredged fill material for embankment (core) construction embankment height 4m‐ 6m (i.e. 5m on average) compacted fine sand with angle of internal friction = 28 to 30; used 30
embankment slope: 1V:3H and 1V:2.5H a factor safely fs ≥ 1.4 has been considered as standard in line with previous project designs for river bank stability (PIRDP).
2.3.2 Assumptions for Embankment Material To ensure least usage of valuable land, specially the top soil, borrow pits are avoided. In this case bulk fill material is river sand. Because of scarcity of land, especially agricultural land, embankment core is proposed to be built with dredged river sand. Minimum 60 cm thick clay cladding over the core surface shall protect the embankment against weather action. The clay material is proposed to be collected from base excavation or from local selected soil or carried far away from construction area. So no borrow pits are proposed. Dredged soil from river bed River bed material mainly fine sand/ very fine sand with silt/ silty fine sand/ silt with very fine sand occasional at shallow depths. The feature of predominant fine particles is observed at shallow depths (5‐7m). Compacted fill material have angle of internal friction φ=28‐30 Slope angle , i.e. slope 1V:3H, 1V:2.5Hd an 1V:2H
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2.3.3 Results of Analysis tan Under normal conditions: Factor of safety against failure, fs = ; Ø 28° to 30°, use 30° tan For Ø 28° , F.S (for 1:3) = 1.6 and for Ø 30°, F.S (for 1:3) = 1.7 For Ø 28° , F.S (for 1:2.5) = 1.33 and for Ø 30°, F.S (for 1:2.5) = 1.44
From the analysis, it would appear that although under normal conditions slope provision of 1V:3H and 1V:2H are adequate, protective measure against seepage flow will be required for construction of embankment considering the fact that the only material available cheaply and in abundant quantity is very fine sand with little to some silt/clay.
At this stage, under the circumstances discussed above the proposed embankment configuration considered from stability and safety consideration can be silty fine sand materials with clay‐cladding all around as shown in fig.1 (a).
It is also proposed to consider slope of the embankment as 1:3 as the preferred option. However, it is also possible to use different slopes at riverside at the second option for the flood embankment configuration as shown in fig.1 (b).
2.3.4 Embankment Alignment and Cross Sections The alignment of an embankment is governed mainly by technical, economical and morphological considerations. Economically the best alignment is that, which can be built efficiently, requiring least land acquisition, causes minimum social impact, uses locally available suitable material and protects land area as much as possible. For this project, the following points have been kept in consideration while finalizing the alignment of the embankment: As far as possible, it has been kept in consideration that the existing alignment of embankment, wherever available, is followed to avoid additional land acquisition and relocation of existing infrastructure and settlements. Set back is carefully fixed considering available bank protection and erosion rate of the river bank. The alignment is preferred to pass over the area, where bulk of fill material/earth is available for construction of the embankment. Sharp corners (bends) in the alignment is avoided not at last for improved road communication. The minimum radius of curves shall be 250m. Due attention is given for avoiding blockage of the existing transportation system. Alignment is preferred to run as far as possible along the higher ground elevation and not across depressions.
The following technical aspects were considered for the embankments: e Along th protected bankline the setback distance is as minimal as possible. Minimum setback distance is 35m, in consideration of not to impose any additional load on the bank slope and to have sufficient setback distance if local failures occur. Mechanical compaction is proposed in embankment construction/ re‐construction. e Th core of embankment will be constructed with dredged sand/silt (dredged from the nearby river). The selection of dredged soil as fill material is made as per provision of BWDB Design Manual and Govt. decision. The section has been designed accordingly to save valuable agricultural land.
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A clay cladding (minimum 60 cm thick) around the exposed surfaces shall be provided to protect the embankment against rain cut and weathering action. The amount of clay for clay cladding shall be available from the base excavation of the embankment. 10m wide roadway to accommodate a 5.5 carriage way (2‐lane rural road) with paved shoulder and grass verge as per specification of RHD shall be constructed on embankment. an RCC road (2.8m wide) will be constructed on 3.2 m wide crest for plying non motorized vehicle (NMV). The RCC road will also be used for maintenance of the flood embankment. The crest allows raising of embankment height due to climate change without disturbing the normal traffic along the roadway.
Embankment section is designed to fulfill the following criteria: The side slope of embankment on country side should remain stable during steady seepage at design high water level The side slope of embankment on river side must be stable during rapid drawdown conditions, where these prevails Phreatic line i.e. top hydraulic gradient line should be well within the downstream face so that no sloughing of the slope takes place. Sufficient 'Free Board' must be provided to avoid the possibility of over topping during the design flood. The u/s and d/s slope should be flat enough, so as to provide sufficient base width at the foundation level, such that the maximum shear stress developed remains well below the corresponding maximum shear strength of the ssoil. For thi a suitable factor of safety should be provided. River side slope is stable against wave run up in case no treatment is anticipated
On the whole the embankment section itself shall be stable against imposed hydraulic, seismic and other anticipated external loads.
For comparison the recommended section in BRE is :
Fulchari‐Sirajganj: (top width; 24.0 ft = 7.3m, Side slope:1V: 3H both side); Sirajganj‐ Bherakhola (Sirajganj): top width: 14.0 ft (4.3m), Side Slope: 1V:3H. Very recently the crest width of embankment from Sirajganj to Enayetpur is extended to accommodate a two lane road with some provision of non‐ motorized vehicle (NMV).
The designed section shall also withstand toe scour and slope erosion due to incident waves during stormy weather. The climate computations are based on IPCC predictions for 2050; 0.50m sea levels rise.
The design has been carried out considering the technical feasibility, satisfying the requirements of economic viability, social and environmental acceptability. In selected locations a berm is provided at the river side of embankment allowing some provision of temporary shelter for erosion and flood victims. The selected cross sections are depicted in Figure 2‐2.
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Figure 2‐2: Embankment section with and without Temp Settlement area.
A long section showing the elevation (DEM) along the embankment alignment is shown in Figure 2.3.
Figure 2‐3: Long section of embankment alignment showing the 100 yr. HWL and embankment crest level
2.3.5 Crest level of Embankment The embankment is designed to keep selected flood heights (100 year HFL with incident waves) and overtopping water out of the project area.
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As per Design Manual (BWDB) the embankment along all the major rivers shall be constructed with 100 year HFL+ 1.5 m free board. Accordingly the embankments along Brahmaputra‐Jamuna and Padma is proposed with a crest level of 100 year HFL+1.5 m Free Board.
The embankments along Hurasagar upto a length of 5.5km from the outfall of Hurasagar at Jamuna shall have 1.5m free board over 100 year HFL (100 year HFL in Jamuna is 13.30 and that at Baghabari in Baral is 13.60m PWD). The embankment along Hurasagar Baral at Baghabari shall have free board of 1.0 m over 50 year HFL (13.20m PWD) and the rest embankment along Karotoa river shall have a free board of 1.0 m over 50 year HFL (13.20m PWD). The crest level of embankment from 5500m to 9500 m along Hurasagar shall have smooth transition.
2.3.6 Set Back Set back is the distance between river bank and river side toe of the embankment. The setback has been determined considering the following criteria; At places where erosion has taken place over past years, a setback is based on the erosion rate. An extra margin equivalent to 10 years ofe th present erosion rate is added to the minimum setback to be applied, if immediate bank protection is not intended. At places where a bank protection is provided or already exists, set back selection takes account only to avoid surcharge due to embankment loading and allowance for emergency repair of protection works. Where embankments are to be provided on both sides of a river, the minimum setback should be determined from the floodway requirement to pass the design flood under confined conditions. If the above criteria cannot be attained, a minimum setback (as per standard norm) from the eroded bank are kept, but bank protection works are proposed to be provided.
2.3.7 New Embankment A new embankment run along a new track further inland from the old (damaged by erosion) embankment. The alignment of this embankment will merge smoothly with the existing portion of the old embankment. At certain locations of the existing embankment, where embankment has already got breached or threatened to be breached in near future due to river action, there is a need to construct a new embankment.
The new embankment proposed under the project (Tranche 1) is from Koizuri to Hurasagar outfall (about 12.5 km) along right bank of Brahmaputra‐Jamuna, and 6.0 km along left bank of Hurasagar at different stretches (already eroded) from Hurasagar outfall to Korotoa outfall. The embankment as described earlier accommodates a 5.5m carriage way plus 1.50m wide shoulders inside the protected area and a 2.8m RCC road along the crest for non‐motorized vehicle (NMV).
2.3.8 Re‐Sectioning of Embankment Due to lowering of embankment by weathering action or by wave erosion or due to settlement the existing embankment sections have become under designed section at many locations. Also due to various past natural calamities and non‐maintenance for a long time, the existing embankment sections have deteriorated at many locations. eTh consideration for global warming and climate change, added need to safeguard areas against selected flood events. In addition to create a provision for a 2‐lane carriage way the re‐design of embankments is necessary. Therefore, design for re‐sectioning of the existing damaged or deteriorated embankment has been tcarried ou to serve the present need and safe guard the project area.
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The re‐sectioning of embankment is proposed for a length of about 10.5 km along the left bank of Hurasagar and left bank of Karotoa. The re‐sectioning mostly follows the old Hurasagar sub‐project embankment. The embankment shall be rehabilitated to accommodate the 5.5m carriage way and NMV as provided for the new embankment.
2.3.9 Road over the embankment Rural Road: On the inner top of embankment a rural road having 5.5m carriage way plus 2x1.5m paved shoulder and 2x0.75m verge is proposed to be constructed. The rural road will have a flexible pavement with 0.2m sub‐grade, 0.2m sub‐base, 0.15m aggregate base type‐II and base course, prime coat and bituminous tack coat as per rural road standard specification.
NMV Road: On the crest of embankment a 2.8m wide RCC carriageway shall be built for non motorised vehicle (NMV). This road is proposed to be used also for maintenance of the embankment during emergency without disturbing the regular traffic.
Gras stone: This is a concrete slab (40x40x15cm) with 4 holes of size 12.5x12.5cm. The gras stone blocks will be placed along both the slope of the crest up to 1.2 m below crest in the country side and 1.5m below crest in the river side of the embankment. Thee gras ston will allow grass to grow through its holes but resist any damage attempt by the people.
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3 Drainage Provisions
3.1 Drainage Channels/Khals The main function of the drainage channel/ khal is to safely drain out the design discharge or the drainage basin runoff generated by 5‐day duration storm of 1 in 10 year frequency. In addition to that increase for precipitation (13% by 2040) for climate change need to be taken in to account.
The design of drainage channel leading to inlet structure is the design capacity of that structure. The design discharge of other channels is calculated as follows:
Design discharge: Catchment area of channel x unit discharge from drainage modulus. Capacity of Channel: The capacity of channel is computed using Manning’s formula.
3.2 Drainage Structures The objective of constructing flood embankment and associated structures is to protect agricultural lands from high flood and to drain out excess precipitation from the area through designed opening i.e. drainage sluices. The farmers use to take water into the project during winter and also during post‐ monsoon for irrigation. Inw vie of above need, the sluices are designed for both drainage and flushing. So a two way regulators for both drainage and flushing have been designed.
The total area under the Hurasagar sub‐project is 7895 Ha (R1 area = 10,882 acre, R2 area = 8618 acre, Total (R1+R2) = 19500 acre = 7895 Ha). Total drainage facility provided under the project was 12 vents‐ 1.5mx1.8m and 3 vents‐1.5mx1.5m. Out of total number of structures constructed under the project, 1V‐1.5mx1.8m, 2 nos and 1V‐1.5mx1.5m‐ 3 nos were totally damaged during 1998 and subsequent floods. The fixation of invert level was also higher in the opinion of local people. To compensate for the higher invert elevation, damaged structure and anticipated future climate change, the provision of additional 7 vents has been kept under the study. In addition to that a 6‐vent (1.5mx1.8 m) structure is proposed at the outfall of khal connecting Kadai Badla Bil to Jamuna with outfall at Koizuri hat.
The existing regulators of the Hurasagar sub‐project shall be repaired to serve the project. 3 regulators are assumed to be repaired to accommodate the project need. In addition 3 regulators shall be added to the project (1‐6 vent 1.5mx1.8m, at outfall of Hurasagar at Jamuna right bank, 1‐1 vent, 1.5mx1.8m at offtake of new Hurasagar, entering the project area and 1‐4vent, 1.5mx1.8m additional at Hurasagar outfall).
In using the existing regulators (repaired and rehabilitated) of Hurasagar sub‐project within the extended embankment as proposed under the project (MRP), the embankment may need to be re‐ designed at certain stretches to accommodate the proposed embankment section.
Runoff from the catchment area (runoff isohyets) under consideration is 30 mm/day. The runoff specified in IECO Master Plan (1964) plus 20% increase over that to account for climate change is considered for calculating the runoff volume of the area under consideration.
The following table provides key design considerations for regulators for this feasibility level study:
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Table 3‐1: Provides key design considerations for this feasibility level study: Location Catchment area (Ha/ventage) Location Outfall River [Northing and Easting] Lochna Existing (4 vent, add 2 vent); 1750 ha 461392E; 665068N Hurasagar/Boral Gala Existing (4 vent; add 4 vent) 3550 ha 465114E; 662557N Hurasagar/Boral Koizuri, Gopalpur 5570 (6 vent‐new) 468742E; 673594N Jamuna Gudhibari 850 (1 vent‐new) 467619E; 671008N Jamuna
3.3 Design Criteria for Hydraulic Structures 3.3.1 General For designing the new or rehabilitating damaged hydraulic structures falling along the alignment of an embankment or along the alignment of drainage canals/ khals, the Internationally accepted standard design criteria including the USBR standards and standard design manual formulated by BWDB (Volume ‐I: Standard Design Criteria) have been used.
Before starting the detail design of the hydraulic structures, a detail field survey and stakeholder consultation was carried out in order to find prevailing drainage problems and assess the effectiveness of drainage system under different hydrological condition. In addition, the information about the existing hydraulic/ water control structures are collected during field survey campaign which is very important for development of drainage model.
The various types of existing hydraulic structures under the project is given below: Drainage regulators Drainage‐cum‐flushing regulators Flushing inlets Bridges/Culverts
A drainage regulator in any basin area is generally designed to drain the excess runoff from the catchment area up to design drainage level. The dimension/ opening vent size of a drainage regulator is calculated based on the average design discharge. The maximum allowable storage level in the project area is assumed as 30 cm above the design drainage level. The drainage level is selected in consideration of the lowest level in the basin.
During certain period of the year, the drainage regulator is also used as flushing inlet to let in the river water into the project area as required for the crop field. The project water level during these stages is assumed to be lower than the design drainage level. All the regulators are therefore designed with the dual purpose of flushing and drainage.
3.3.2 Design Flood Frequency Generally for the normal flood protection works, the frequency of occurrence of floods that needs to be selected for the design of a particular embankment depends on the acceptable extent of damage by inundation in the locality. Considering likely agricultural damage to important installations and loss of human lives, the following flood frequencies are usually adopted in Bangladesh;
1:20 years flood, where agricultural damage is predominant. 1:100 years flood, where loss of human lives, properties and installations are predominant.
For the purpose of this feasibility level study, the crest level was set equal to the embankment crest level.
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3.3.3 Crest level of Structure All the structures i.e. the regulators are the integrated parts of the embankment system, the crest level of all the regulators are maintained same as the embankment crest at the location where it is placed.
3.3.4 Design of hydraulic structures (Drainage cum flushing Regulator) In general, the design of a hydraulic structure is carried out in three steps;
First step: hydrological analysis is carried out, which determines the design discharge of the hydraulic structure. Second step: hydraulic designs are carried out to determine the optimal location, configuration of components of the structure, waterway requirement, protection against scour, seepage and uplift pressures, energy dissipation arrangements etc. Third step: structural designs carried out for evaluating the forces/ stresses on each component of structures on account of dead loads, dynamic loads, seismic loads and earth pressures and each component is designed to resist the forces and bending moments caused by all these loads.
3.3.5 Setting out Invert Level of Structure The invert level of all the regulators are fixed mainly on the basis of drainage requirement and the retention level desired to be maintained within the catchment. In most of the cases the need for energy dissipation through a designed stilling basin at the both end of the structure dictates the invert level below av. LWL in the outfall river during the drainage period.
Generally, the invert level of the drainage‐cum‐flushing regulator structure is kept 0.30 to 0.60 m higher than the project side drainage channel/ Khal bed level. The consideration of slightly higher invert level will help to retain water in the polder area and also it will improve the structure operation conditions by reducing the possibility of sediment deposition in the structure conduit and secure tail water depth during the initial stage of flushing.
3.3.6 Hydrological Design For obtaining the design discharge of a drainage‐cum‐flushing regulator, a 5‐day duration storm of 1 in 10‐years return period expected over the catchment area has been considered, accounting the variable country side or river side water levels during considered period. The design discharge is computed on the basis of unit discharge for draining the catchment area with the set of drainage structures in anticipated climate change condition.
The preliminary design of drainage‐cum‐flushing regulator has been carried out on the basis of drainage and flushing requirement assumed for the project.
For the right bank of Jamuna, WL Gauges considered for the water level in the outfall rivers are Sirajganj (SW 49), records available from January 1945 to September 2012 and Mathura (SW50.3), records available from August 1964 to September 2012. The WL gauges are maintained by BWDB along the right bank of Brahmaputra‐Jamuna.
The interpolated 010 year HWL, HWL (observed), LLWL and Av. LWL in the area of interest (Koizuri‐ Hurasagar) along the Brahmaputra‐Jamuna is 13.30 m PWD,12.90 m PWD, 3.60 m PWD, 4.20 m PWD respectively.
Similarly for the left bank of Jamuna, WL Gauges considered for the water level in the outfall rivers are Bangabandhu Bridge, records available from October 1994 to January 2013 and Aricha (SW 50.6),
Page 59 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program records available from August 1964 to August 2012. The Bangabandhu Bridge WL gauge is maintained by BBA and Aricha gauge is maintained by BWDB.
The interpolated 100 year HWL, HWL (observed), LLWL and Av. LWL in the area of interest (Chouhali‐ Nagarpur) along the Brahmaputra‐Jamuna is 13.95 m PWD,13.10 m PWD, 4.50 m PWD, 4.95 m PWD respectively, and those in Jafarganj‐Bachamara is 11.80 m PWD, 11.25 m PWD, 2.50 m PWD and 3.00 m PWD respectively.
In selecting the details of drainage cum flushing regulators the av.LWL, av.HWL and average low level of the basin are the guiding factors.
3.3.7 Fixation of Vent Size and Design Discharge The opening size of the regulator for the drainage‐cum‐flushing regulator has been fixed in such way so that it can safely pass the design discharge computed from the hydrological analysis. The flow through a regulator is mainly dependent on the upstream and downstream water levels and invert level. The discharge through a vent or orifice depends on discharge coefficient and the discharge coefficient mainly depends on the entrance coefficient, Ke. The generalized formulae for calculating the discharge through the square ended entrance in the various types of flow conditions are presented in table below:
Table 3‐2: Conditions of flow Sl. No Flow Type Flow Conditions Discharge by the formula 1 Submerged/drowned orifice H1 > H2 > V ht Q = 0.802*(B*Vht)*(2*9.81*ΔH) (0.5) (Flow Type‐1) 2 Free orifice H1 ≥ 1.5 * V ht Q = 0.60*(B*Vht)*(2*9.81*h) (0.5) (Flow Type‐3) & H2 ≤ V ht 3 Submerged/drowned weir H1 < 1.5 * V ht Q = 0.816*(B*d)*(2*9.81*Δh) (0.5) (Flow Type‐4) & H2 > H c 4 Free over flow weir H1 < 1.5 * V ht Q = 0.305*(B*H1)*(2*9.81*H1) (0.5) (Flow Type‐5) & H2 ≤ H c Ref: Standard design manual (BWBD)
Where, H1 = Upstream water depth above invert level
H2 = Downstream water depth above invert level Hc = Critical water depth = (q2/g) (1/3) ; q is the discharge intensity (m3/s/m) Vht = Vent height of the barrel
ΔH = H1 – H2 h = Measured height at the orifice center line = H1 ‐ Vht / 2 d = Depth of flow within culvert
Δh = Difference between upstream and downstream water levels within culvert = H1‐d B = Total opening width of the barrel
For the drowned/ submerged weir type flow condition, the tail water rating curve for the outfall drainage canal may be developed and the upstream water depth H1 is known. The two unknowns ‘Q’ and ‘d’ can be calculated by trial and error.
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In the analysis, it is assumed that the only flow conditions Type‐3 and Type‐5 generate hydraulic jumps and that necessitate a stilling basin depending upon the Froude No. (F1).
3.3.8 Drainage capacity of regulators For computing the preliminary design capacity of a regulator the procedure followed are described below:
Assumed runoff (30mm/day) with 20% increase due to climate change a basin of 850 ha area produces a design discharge of 3.54 m3/sec. A regulator, 1V‐1.5mx1.8m, with invert at 7.00 m PWD and basin WL at 8.5m PWD can drain 4.30 m3/sec with a head difference of 1.0m. The Basin WL is the minimum WL to be drained. Under this condition the regulator can drain only 21.38% higher than the total discharge generated in the basin.
In another exercise under the similar topographic and hydrologic condition a 3600 ha basin produces a design discharge of 15.0 m3/sec. A regulator 4V‐1.5mx1.8m with invert at 7.00 m PWD and basin WL at 8.5 m PWD can drain 17.20 m3/sec with head difference of 1.0m. Under this condition the regulator can drain 14.64% higher than the generated discharge. The lowest basin level being at +8.0 m to +9.0 m PWD.
The outfall water level (average) being at 6.30 m PWD in April, 7.90 m PWD in May, 9.80 m PWD in October and 7.60 m PWD in November allows drainage in different period when necessitates.
The head difference is assumed to be 1.0m with basin WL and corresponding river WL during the drainage period. On the basis presented above a regulator of size 1V‐1.5mx1.8m is proposed for a basin area of 850 ha or less. Ventage of a regulator for a catchment area may be approximately calculated as 1V‐1.5mx1.8m for each 850 ha of catchment plus one vent for any part of 850 ha for the project under consideration.
The regulators proposed under the project on restored BRE, from Koizuri to Hurasagar (Bherakhola), and on the flood embankment of Hurasagar sub‐project (from Bherakhola to Shahjadpur) are:
i) 6V‐1.5mx1.8m‐2 nos at Koizuri (outfall at Jamuna) ii) 1V‐1.5mx1.8m‐1 no at Gudhibari (outfall at Jamuna) iii) 4V‐1.5mx1.8m‐ 1 no at Gala (outfall at Hurasagar/Boral) iv) 2V‐1.5mx1.8m‐1 no at Lochna (outfall at Hurasagar/Boral)
The locations of proposed regulators (JRB 1, Tranch‐1 ) are shown in Figure 3.1.
In addition to that 3 existing regulators at Bherakhola, Andermanik and Lochna shall be repaired and rehabilitated under the project.
However, the selection of size shall be finalized after detail survey conducted during detail design phase.
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Figure 3‐1: Showing the location of all proposed regulators under Tranch‐1 (JRB‐1)
3.3.9 Hydraulic Design The hydraulic design of a structure mainly fixes the profile/dimension of the structure, which can safely dissipate the hydraulic energy, counteract the seepage and uplift pressure, the scouring activity etc. Generally, hydraulic structures are subjected to seepage of water beneath the structures and the water seeping below the body of the structures that endangers its stability and may cause its failure, either by:
Piping or undermining by direct uplift by scour
The purpose of the hydraulic design is to provide necessary measures which will ensure its safety against failure caused due to the above reasons.
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Figure 3.2 below explains the basic assumption for calculating the exit gradient and creep.
C/S R/S ------
(1) (2)
(2) (1) 1 2 d d - - - Cutoff wall
b' b
Figure 3‐2: Long section of Regulator showing water levels in R/S and C/S
Total Floor Length (b): 57.90 m; Length of floor from u/s cutoff to d/s cutoff: 57.0 m (1) Drainage Condition: (a) C/S water Level: 8.50 m PWD (b) R/S water level: 7.5 m PWD; Exit Gradient: 0.029 < 1/7 = 0.143; OK
(2) Flushing Condition: (a) C/S Water Level: 8.00 m PWD (b) R/S water Level: 9.00 m PWD Exit Gradient: 0.033 < 1/7 = 0.143; OK
On operating allowable creep is 6.00, available creep is 27.87; again with the extreme condition generated during highest high flood the creep generated is 13.20, which is also much lower then the available value.
3.3.10 Energy dissipation arrangement The energy of flow through a regulator is normally dissipated through the formation of a hydraulic jump within a designed stilling basin. Whereas, the length of a stilling basin is generally determined from the length of hydraulic jump required to be confined within the length of the stilling basin.
An energy dissipation arrangement of a structure requires following components to be provided:
A sloping glacis, generally sloping downward at a slope of not steeper than 1V:3H. A stilling basin, with sufficient length for dissipation of energy A cutoff wall at the end of floor of stilling basin. hThe dept of cutoff wall is kept below the maximum possible scour level for the designed discharge intensity of flow. Protection work at exit end of the structure as flexible floor in graded inverted filter beyond the end of stilling basin Launching apron in two layers of loose cement concrete blocks beyond the end of flexible floor.
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A typical longitudinal section is given below in Figure 3.3 to explain the detail
Figure 3‐3: Long section of Regulator showing basin and flexible protection at end
3.3.11 Structural Design
The structural design of all the components of a structure shall be carried out following the standard code of practice, Standard Design manual of BWDB and using the specified type of materials.
(Typical design calculation and drawing for a 4V‐1.5mx1.8m flushing cum drainage regulator is enclosed in Appendix)
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4 Riverbank Protection Works
4.1 Proposed Works The bank protection work has been proposed at the location where there is active bank erosion. The stretches where the eroding bank is very near the existing valuable infrastructures or settlements, are also selected under Tranch‐1 for immediate bank protection.
The stretches considered for bank protection under Tranch‐1 are
(i) 1 km in Benotia at the right bank of Brahmaputra‐Jamuna (ii) 5 km at Chouhali at the left bank of Brahmaputra‐Jamuna (iii) 2 km at Jafarganj at the left bank of Brahmaputra Jamuna (iv) 7 km at Harirampur at the left bank of Padma.
Locations of all protection works under Tranch 1 (JRB1, JLB2 and PLB1) are shown in Figure 4.1.
In designing bank protection structures the experience gained and lessons learned from the protection works executed in JMREMP has been followed. In JMREMP revetment for a long reach using geobag under water and cc block above wlo water has proved to be very economic and sustainable. The same system and technology has been followed in designing the bank protection structures.
Figure 4‐1: Showing Locations of Bank Protection Works under Tranch‐1
4.2 Hydrological Observations The Brahmaputra/ Jamuna drains an estimated volume of 620 109 m³ of water per year into the Bay of Bengal with an annual average discharge of 19,600 m³/s. Each year the river reaches a bankfull discharge at about 48,000 m³/s. Maximum discharge of about 100,000 m³/s were observed during the 1988 flood. The Brahmaputra/ Jamuna shows the largest sediment grain sizesd an transports the largest sediment load. The median diameter of the bed material decreases from 220 mm near Chilmari to 165 mm near Aricha. The median diameter just downstream of Bangabandhu (Jamuna) Bridge is about 180 mm. The river stage varies by about 6.0 to 7.0 m.
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The Padma, which is draining the combined flow of the Brahmaputra/Jamuna and the Ganges and the lower reach of which is weakly influenced by the tide during the period from December to April, has an annual average discharge of about 28,000 m³/s. The seasonal water level variation is about 6 m. The bed material sediment of the Padma varies from 140 mm in the upper reaches to 90 mm in the lower reaches.
For the major rivers of Bangladesh the statistical return period of the bank full discharge is between one and one and a half years.
Bristow (1987) proposed a classification of river channels into different orders. The entire channel is the first order channel and comprises a number of smaller second order channels. The latter have slightly different characteristics and as a result they show a different behaviour in terms of water level slopes as well as the discharge and sediment capacities. The shifting characteristics of the river can be divided according to the order of the channel. The rate of shifting of the first order channel is 75 to 150 m per year. The second order channels change their course continuously. Larger channels are abandoned and new ones develop in a few years only. A bank erosion rate of the second order channels of 250 to 300 m per year is common, but in extreme cases it can be more than 800 m per year.
Bank erosion rates of the three main rivers are very similar. However, at Ganges dan Padma, the bank erosion is restricted to the boundary of the active corridor, which consists of alluvial and deltaic silt deposits, whereas the floodplain outside of it is more resistant to erosion. At the Brahmaputra/ Jamuna the flow attacks any of the banks and new channel courses outside the active flood plain are created frequently.
The driving forces for erosion are the high shear stresses by current flow, which exceed the shear strength of the soil. The bed erosion at the toe in vertical direction will cause bank erosion and a self‐ induced adaptation to a slope which is milder ethan th critical one. For the design of a protection structure, the importance of scouring is evident and consequently has to be taken into account in the design phase. The hydraulic design parameters, e.g. design water level and design flow depth, act as boundary conditions for the morphological parameters. The scouring to a certain scour depth is the decisive phenomenon and consequently the main parameter for the design. However, an estimation of the flow velocities is needed to optimise the size of protection element, construction phase of the protection work, placing of materials and protection elements.
4.3 Data for Bank/Slope Protection For designing the protection works, the following hydraulic parameters are required to be established/ obtained:
Water level corresponding to maximum/dominant discharge Maximum discharge / dominant discharge River cross sections Flow velocity Significant wave height Silt factor of river bed material Observed/anticipated maximum scour Wind speed and duration Wave characteristics (fetch length, wave height and wave period
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4.4 Elements of Slope Protection Slope protection consists of a layer of hard cover and a filter layer over the slope along the reach of embankment or river bank above LWL. The cover layer must be able to resist hydraulic impacts (current and waves) while the filter layer in between cover layer and core materials is responsible to prevent migration of subsoil particles out of the bank slope (retention criteria) and at the same time to allow movement of water through the designed filter (permeability criteria). The revetment used for bank protection works must have the following qualities and characteristics:
The surface of individual elements eof th cover layer should be sufficiently resistant against abrasion by wave and current attack The individual element should have sufficient weight so that it cannot be dislodged/ lifted by uplift forces The filter layer should prevent migration of soil due to seepage pressure typical in tidal condition. Should be stable to withstand the forces against sliding in low tide condition and residual pore pressure present in itself and other adverse hydraulic conditions. Bank slope and embankment slope constructed by earth need to be stable against seepage, drawdown under normal condition etc. for any type of protection to be applied.
Hand pitched cc blocks are the recommended protection system for the slopes of standard revetment structures above the average low water level (av.LWL). Concrete blocks are more durable than bricks and less attractive to pilferage. If well dimensioned, they are able to suit any flow condition. Sizes of 20‐ 40 cm have proven to be sufficient to withstand the hydraulic loads occurring at the Jamuna river.
4.5 Design Discharges 4.5.1 Total River Discharges and Number of Channels The protection work means protection of river bank itself and the protection of river side slope of embankment. The purpose of protection is to stabilize its slope and achieving protection against erosion and scour.
The discharge of a specific river is obtained from the analysis of hydrological data, especially through extrapolation of stage discharge relations at water level stations, where also discharge measurements have been executed regularly.
The bankfull discharge can be taken from Table below.
Table 4‐1: Bankfull Discharge of Major Rivers River Bankfull discharge Return period of bankfull Braiding Index (‐) (m3/s) discharge (years) Jamuna 48,000 1.0 4 – 5 Ganges 43,000 1.4 1 Padma 75,000 1.05 1
Discharge characteristics for major rivers of Bangladesh (Source: Guidelines and Design Manual for Standardized Bank Protection Structures (FAP‐21)
The design discharge Qch for a channel can be calculated by:
Qch = C1/Cb. 2. Qb and Bankful discharge for a canal can be calculated by
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Q b,ch = Qb/Cb
3 Where, Qch = design discharge, Canal (m /sec) 3 Q b.ch = bankful discharge, canal (m /sec) 3 Qb = bankful discharge, river (m /sec)
C1 = safety factor for extreme canal discharge (C1 =1.5)
Cb = Braiding Index (for Jamuna, Cb = 4 to 5, Padma, Cb =1.0)
The design discharge Qch for the left channel of Jamuna according to this approach is Qch = 1.5/4x2x48,000 m3/sec = 36,000 m3/se
4.5.2 Flow Distribution in anabranches (a) Brahmaputra‐Jamuna The forecasted flow distributions along the anabranches under hydrological condition (a) and (b) at the erosion vulnerable area at Chouhali are shown in Table below, [Source: Chouhali‐Nagarpur Feasibility Study, IWM]. Hydrological Condition (a) 2003 monsoon 2004 monsoon 2005 monsoon (assume that last three years monsoon will repeat for 2006, 2007 and 2008 respectively). Hydrological Condition (b) 2001 monsoon 1998 monsoon 2001 monsoon (assume that average dry year of 2001 for 2006 monsoon, extreme flood year of 1998 for 2007 monsoon and again average dry year of 2001 for 2008 monsoon respectively).
Table 4‐2: The Simulated flow distribution along anabranches of the Jamuna under hydrological condition (a) & (b) Channel Flow distribution in % Hydrological Condition (a) Hydrological Condition (b) 2006 2007 2008 2006 2007 2008 Right Channel 71% 65% 69% 75% 62% 60% Left Channel (Chouhali) 29% 35% 31% 25% 38% 40%
In this case the designer is mainly concerned with the left channel (Chouhali channel). In all cases the model has generated a maximum of 40% of flow through the left channel.
Under this condition (as per model Study, IWM),
3 with Q (100 yr) = 100,000 m /sec 3 Qch = 100,000 x 0.4 = 40,000 m /sec
In calculating the scour in the left channel (Chouhali) of Jamuna, the channel discharge (calculated by model study) used by IWM (Nagarpur‐Chouhali Project, FS) is 30,129 m3/sec.
Considering the different approach of calculating the discharge through the canal under consideration, 3 the Qdesign is taken as 36,000 m /sec
(b) Padma Discharge measurements conducted in Mawa by BWDB show that out of 321 observations from 1994 to 2012, maximum discharge (Qmax) is 116,000 m3/sec, average discharge (Qav) is 55,900 m3/sec, maximum velocity (Vmax) is 4.35 m/sec and average velocity (Vav) is 2.67 m/sec. Analysis conducted by Padma Bridge Study team recommends a bankful discharge of 70,000 m3/sec at about EL 5.5m PWD, but at higher elevation bankull discharge is higher.
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Using the Regime type relations derived for the major rivers of Bangladesh by different studies (Klaassen and Vermeer, 1988; Delft Hydraulics and DHI, 1996), related channel bankfull width (W) and section‐averaged bankfull depth (d) to bankfull discharge (Qb) is expressed as:
C W = aQb
Where a and c are the coefficient and exponent of Qb. Magnitude of 'a' varies in a very wide range, but the magnitude of 'c' is found to be very close to 0.5.
0.5 2 Thus, W aQb or Qb 1/a W
For preliminary assessment of bankfull discharge of any anabrach of a braided or anabranching channel bankfull discharge could be distributed based on the ratio of square of bankfull width of the channels.
The discharge in anabranch along the Harirampur can be maximum 70% of the total. To this effect the 3 Qdesign for dominant discharge is 52,500 m /sec.
4.6 Design Water Level A stage discharge relation (rating curve) established at the location of the planned structure from long term monitoring of daily averaged water levels and corresponding discharges can be used. For selected locations, data is available from the BWDB. From the average daily water level the average low water level (av.LWL), average high water level (av.HWL) and 100 yr HWL are calculated. The DWL (Design Water Level) is generally above the Flood Plain Level (FPL) and the return period of bankfull discharge for Jamuna, Ganges and Padma is between 1.0 and 1.4 years.
100 year HWL, Observed HHWL, Av. LWL and LLWL for Jamuna River at Koizuri, Benotia, Chouhali and Zafarganj are given in section 6.2.4 of this report.
For calculating Water level of Padma river at Harirampur, WL gauges considered are Baruria Transit (91.9L) and Mawa Transit (93.5L). The interpolated 100 year HWL at Harirampur is 8.70 m PWD, observed maximum HWL is 8.50 m PWD, average LWL is 1.50m PWD and LLWL is 1.00 m PWD.
An example of design water levels with respect to embankment crest levels is provided in Figure 2.3.
4.7 Flow Velocity 4.7.1 Requirements To get basic design data, also the prevalent flow velocities should be recorded, providing horizontal and vertical velocity profiles. If possible, velocity measurements should be done during monsoon season (bankfull discharge), otherwise extrapolation is needed, to estimate the design conditions.
It has to be taken into account that, maximum flow velocities occur a few days before the maximum water level is reached. Therefore, it is physically more accurate, to consider a peak flow instead of the design discharge for the evaluation of the design flow velocities.
The design flow velocities in the approach flow of a planned protection structure can be determined in various ways. It should not be estimated only for the deepest point of the approach channel cross section but also along the whole bank through:
Statistical analysis of observed flow velocities;
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Simulation in a 2D (depth averaged) mathematical model or in a physical model; Theoretical calculation methods.
4.7.2 Brahmaputra‐Jamuna River In the case of Brahmaputra‐Jamuna river the recorded measurements from BWDB and the recommendation from Guidelines and Manual for Standardized Bank Protection Structures (FAP‐21) is followed
Flow Velocity measured by BWDB at Bahadurabad Transit during: 1990 to 2009. Total number of observations: 1695
Table 4‐3: Measured Velocity in Bahadurabad, Jamuna Range of Velocity (m/s) nos % 0.0 to 1.0 187 11.03 1.0 to 2.0 1115 65.78 2.0 to 3.0 356 21.00 3.0 to 3.5 4 0.23
Maximum observed = 3.68 m/sec Minimum observed = 0.59 m/sec
The mathematical model study conducted under Chouhali‐Nagarpur FS shows that an erosive near bank velocity (> 1.2 m/s) would be generated at Chouhali bank under both hydrological condition (a) and (b). The strong eroding velocity (around 2 m/s) would occur in future due to confinement effect of the channel which might influence the river bed degradation and bank erosion.
Again the recommendation from the Guidelines and Manual for Standardized Bank Protection Structures (FAP‐21) is as follows:
Table 4‐4: Limits of Standard Bank Protection Structures Structure Category Depth Averaged Flow Design Wave Total Scour/Water Expected Impact Velocity, u [m/s] Height, Hs [m] Depth [m] Light <1 <0.25 <10 Moderate >1.0 ‐ 2.0 0.25 ‐ 0.5 10‐20 High >2.0 ‐ 3.0 0.5‐1.0 20‐30 Very High >3.0 >1.0 >30
From the above observations a flow velocity of 3.00 m /sec is selected for the design of straight to areas under medium bends, for acute bends and protrusions a velocity of 3.5 m/sec is considered for design.
4.7.3 Padma River Depth averaged maximum velocity varies from 2.1 to 2.7 m/ sec with an average of 2.5 m/sec. (USDR, Padma Bridge Design Report). Model study conducted by IWM on Haimchar Design states that, the simulated maximum near bank depth integrated speed appears near Haimchar within the range of 2.75 to 3.00 m/sec during moderate condition, 3.00 to 3.25 m/sec during extreme and longer‐term conditions. So in case of revetment design for Padma river at Harirampur, the design velocity is taken as 3.0 m/sec and for protrusions it is taken as 3.5 m/sec.
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In Chandpur adjacent to Puran bazar (Ibrahimpur Sakua) and in Haimchar in Lower Meghna river and in Sureswar in Padma River depth averaged highest design velocity considered is 3.0 m/sec. The executed work from 2007‐08 appear to be stable after several years of observation.
4.8 Size of bed material 4.8.1 Bed material for Brahmaputra‐Jamuna The Guidelines and Manual for Standardized Bank Protection Structures (FAP‐21) describes that the median diameter of the bed material of Brahmaputra‐Jamuna decreases from m220 mm near Chilmari to m165 mm near Aricha. The average size being about 0.20 mm. In Chouhali‐Nagarpur FS the size of average bed materiald use is 0.18 mm (IWM).
In this case average size of bed material used is 0.18mm (i.e. d50 = 0.18mm)
4.8.1.1 Scour at Brahmaputra‐Jamuna The scour depth has been assessed from Lacey’s formula by applying appropriate scour multiplication factor.
Lacey's Regime Equation
R = 0.47 (Q/f)1/3
Where: R = Regime scour depth (m) Q = Design discharge (m3/sec) f = silt factor = 1.76 (dm)1/2 dm = average diameter (d50)
3 3 Using the 100 yr maximum discharge (Q100 yr), Qch (design) and dm as 100,000 m /sec, 36,000 m /sec and 0.18mm respectively, the regime scour depth (R) is 17.11m
The eroding area being located in an moderate bend, total scour is 1.5*17.11 = 25.66 m Say 26.0 m HWL (High Water Level) at 13.10 m PWD
So the level (depth) of maximum scour at (13.10 m PWD‐26.00 D)m PW ‐12.90 m PWD. However, for additional safety, the scour is assumed at ‐16.00 m PWD
The computed scour shall be checked with the observed scour at similar locations and during different time period of the year. In general a long series of scour observations in similar locations is more representative of actual situation than the computed theoretical scour.
Table 4‐5: Empirical multiplying factors for maximum scour depth
Nature of Location Factor 1 Straight reach Straight reach of Channel 1.25 2 Moderate Bend 1.50 3 Severe Bend 1.75 4 Right angle or abrupt turn 2.00 5 Noses of piers 2.00 6 Alongside cliff and walls 2.25 7 Noses of Guide banks 2.75
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4.8.2 Bed material for Padma The bed material sediment of the Padma varies from 140 mm in the upper reaches to 90 mm in the lower reaches. The Updated Scheme Design Report (USDR) of Padma Bridge Study suggests 0.13mm as the size of bed material.
4.8.2.1 Scour at Harirampur 3 Using the design discharge, Qdesign = 52,500 m /sec and dm = 0.13 mm in Lacey's Regime equation: R = 0.47 (Q/f)1/3 , f = 0.63 R = Regime depth = 20.50 m.
The eroding area being located at moderate bend, the scour depth is 1.5x20.50m = 30.75 m
With WL at 5.75 m PWD, the scour level calculated is ‐25.00 m PWD. Observed bed levels in Four x‐ section measured (from 1971 to 2007) at Padma (RMP 2, 3,4 and 5) show maximum scour depth of ‐ 14.5 to ‐37.0 m PWD and an average lowest bed level of ‐9.60 to ‐16.90 m PWD. So a maximum scour at ‐30.00 m PWD is assumed for the design.
4.9 Waves The maximum wave heights are generally caused by maximum wind speed over the longest fetch length. From observations it is concluded that the maximum wave height with a return period of 100 years for the design of bank protection structures along the Brahmaputra‐Jamuna River should be about 1.3 m. For a return period of 25 years a design wave height of 1.0 m is commonly used for major rivers of Bangladesh. In this case a wave height of 1.3m is used. (Guidelines and Manual for Standardised Bank Protection Structures, FAP‐21)
4.10 Design Cross Section A morphological analysis of measured cross‐section serves as the best approach to derive information on the expected water depths and the cross sectional shape. The bankfull channel width and the bend curvature is also available from satellite images and planform analysis. Data of the Jamuna River consist of yearly measured standard cross sections recorded during the lean season.
To estimate the outer bank profile and the maximum water depth in the thalweg, an envelope curve of measured cross sections (with superimposed cross‐sections) is used. Figure 4.2 represents on envelope of x‐section measured along LB of Jamuna at Chouhali.
From surveyed cross sections of the respective channel a protection structure is planned/designed. Only representative cross sections, which are not affected by any river training structure has been used.
Page 72 September 2013 Technical Designs for Tranch‐1 Work
Figure 4‐2: Envelope cure of measured cross‐sections
4.11 Selection of Type of Bank Protection The stability of unprotected river banks depends on a number of factors which have to be assessed carefully in the process of selection and design of suitable protection measures. A reliable assessment of potential causes of bank failure is indispensable for the success of any measures, i.e. for the integrity of the selected bank protection system and thus the stability of the river bank.
Passive bank protection measures are primarily armored structures or armor layers preventing a bank line from erosion but which do not create significant interference with the flow. The hydraulic influence on the local flow condition is limited to changes in bed roughness. So, in this case the selection of a passive bank protection method is the primary choice.
Typical passive measures are revetment structures, which are built more or less parallel to the flow to form an artificial sloped river bank.
Hand pitched cc blocks are the recommended protection system for the slopes of standard revetment structures above the water line. If well dimensioned, they are able to suit any flow condition.
Geotextile sand containers (geobags), which can be tailored locally, are simple to be installed and proposed to be used for areal coverage below LLWL (Lowest Low Water Level) for protection of bank slope and revetment toe.
The experience gained from implementation and monitoring of the protection work executed in JMREMP has been followed in designing bank protection measures under the project.
4.12 Size and thickness of protection element: The size of cover layer material have been calculated by Pilarczyk formulae and checked with USACE and JMBA equation considering stability against velocity and wave.
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4.13 Size of Elements for Bank Protection The following various elements of revetment have been selected/calculated based on design criteria and design data. 4.13.1 Slope Protection above av.LWL: Top Level of Revetment: The top level of revetment is set at existing bank level or flood plain level where the flood embankment is not provided or the flood embankment is not affected by wave erosion. In case of any wave attack on flood embankment, slope protection is provided against anticipated wave. The bank slope above LWL and the river side of embankment is protected by CC blocks placed over a filter. The size of protection element is the higher size against wave and flow velocity. The top level of revetment works at Chouhali is at flood plain level i.e. at 11.00 m PWD.
Low Water Berm: At a level of about 2.00 m below av.LWL (about +3.5 m PWD in Chouhali) about 5.0 m wide berm is proposed to increase the stability of the bank slope.
The bank slope/Revetment slope from LWL berm to the top (Flood Plain Level) shall be 1V:3H.
Protection Element above av.LWL: For slope protection above av.LWL, two rows of cc blocks of size 400x400x200 mm, followed by one row of cc blocks of size 400x400x300 mm shall be placed on dressed and compacted bank slope.
Filter Materials: Minimum 3 mm thick needle punched geo‐textile filter is used over minimum100 mm compacted sand (FM≥1.5) fill. The geotextile filter shall be placed at least 1.0m beyond the outer edge of LW berm at lower end and at least 1.0 m extra beyond the cc block on flood plain, at upper end, and keyed to the ground. 4.13.2 Under Water Slope Protection: Protection Element on LW berm: The LW berm and slope from LW berm to av.LWL shall be protected with 2 layers of 300x300x300mm cc block laid on 1 layer of 125 kg geobag over the geotextile filter.
Protection element for areal coverage: The areal coverage shall extend from outer edge of LW berm towards deep river for a length of about 30.0 m. The areal coverage shall be composed of minimum 3 layers of 125kg geobags. The thickness of areal coverage shall be minimum 0.52 m. In protrussion 250 kg geobags has been proposed to be used in Jamuna and also in Padma.
Performance of 125 kg geobags used in Jamuna as protection element under normal condition and in moderate bends is quite satisfactory. 250 kg geobags used in Sureswar in Padma and Ibrahimpur‐Sakua and in Haimchar in Lower Meghna river is found to be quite effective as protection element.
However, dumping process followed in case of areal coverage executed through manual labour and properly positioned barge prefers 125 kg geobags as maximum unit size. 4.13.3 Launching Apron: Design scour level: The design scour levels of revetment is calculated on the basis of Lacey's regime theory. The scour calculated in Chouhali is ‐16.0 m PWD. (Ref. Appendix I for scour computation).
Apron Setting Level: The length of launching apron normally depends on the apron setting level and the maximum anticipated scour level. In case of construction in river proper apron setting level varies place to place depending on bed levels just before construction. However, in the present case the extent/ length of areal coverage is decided in a way that any scour at the end of areal coverage shall tno affect the slope immediately.
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Launching Apron: The length of launching apron at the end of areal coverage shall be 15.0 m. Thickness of launching apron is proposed to be minimum 3 layers of 125 kg geobags. In protrussions design proposes use of 125 kg and 250 kg geobags as protection element. The 15.0 m launching apron can protect a scour of 15.0 m with only 5‐7m of the apron is launched. In Brahmaputra‐Jamuna the scour in one season, in an area protected by revetment can be in general maximum 15.0 m.
(Design Calculation and Design drawings for revetment works at Chouhali is enclosed in Appendix‐I)
4.14 Summary Quantities The quantities adopted for key protection work and elements are provided in Table 4‐7.
Table 4‐6 General quantities adopted for Jamuna and Padma Jamuna Padma Under water Length of slope 30 m 35 m No. of 125kg geobags on slope 240 (in 3 layers plus 1) 280 (in 3 layers plus 1) Length of apron 15 m 15 No. of 125 kg geobags apron 120 (in 3 layers plus 1) 120 (in 3 layers plus 1)
Table 4‐7 Quantities adopted for the design JRB‐1 JLB‐2 Chowhali JLB‐2 Jaffarganj PLB‐1 Under water 125kg geobags [No] 379,000 1,760,000 684,000 1,449,000 250kg geobags [No] 0 102,300 51,000 1,169,000 Above water Earth cutting [m³] 143,900 544,700 258,000 460,000 Geotextile sheet [m²] 38,200 188,400 72,000 150,700 Filter sand [m²] 2,500 11,000 4,100 Tranche‐2 Loosely dumped blocks [No] 40x40x30 cm 43,000 215,000 80,000 40x40x20 cm 113,500 567,500 218,000 Tranche‐2 30x30x30 cm 190,000 950,000 380,000
5 Estimate The estimated cost for different interventions proposed under Tranch1 are formulated as per prevailing market rates of construction materials, skilled labour, unskilled labour and hire charge of equipments. In analysing the unit rate for items of works standard analysis format of BWDB has been used.
Estimate for embankment: For construction of embankment in JRB‐1, the rate used under Bogra Circle for construction of embankment by dredged sand/earth from the river has been used with a multiplying factor of 25%. The clay lining in embankment is also taken from Bogra Circle and is applied with 25% increase.
Estimate for Revetment works and structures: The estimate for the revetment works has been formed on the basis of analysed rate as per present market rate of cement, stone chips, geotextile fabrics, geobags, filling sand, hire charge of equipments and wage of unskilled and skilled labours. The unit rate
Page 75 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program for under water dumping of geobags for areal coverage and construction of launching apron is attained following the method and sequence of JMREMP.
Finally the rate per meter of protection in Jamuna river attained was 55% to 60% higher than the average cost incurred in case of JMREMP protection. The applied rate for Jamuna protection was 75% above the average rate achieved in JMREMP work in Kaitala‐Mohanpur (2003‐04). Again in consideration of additional scour the applied rate for Padma protection is considered 15% higher than that of Jamuna.
The estimated rate of regulator was taken from the analysed rate used in CEIP work presently (2013) under process.
Estimated cost for Total Physical Work is :
Total Physical Works BDT US$ Tranch‐1 4,668,390,449 58,354,881 Tranch‐2 7,183,026,277 89,787,828 Tranch‐3 7,998,558,187 99,981,977 Total 19,849,974,913 248,124,686
Note: For calculating cost of embankment construction in Tranch‐2 and Tranch‐3, 1m of excavation below embankment base is kept unchanged to accommodate any future change in drainage cost.
The Land Acquisition area has been calculated through the Land Acquisition and Resettlement plan. The total cost for the project will therefore be the amount adding the Land Acquisition and Resettlement cost plus engineering and investigation plus logistics.
The preliminary estimates for Tranch‐1, Tranch‐2 & Tranch‐3 and somee of th basic rates of elements used in the estimate is placed as Appendix‐III.
6 Alternate Approach for Protection
The embankment along Jamuna and also along Hurasagar/Boral might be affected by wave action at certain stretches. To take measure against wave erosion the stretches vulnerable to wave action shall need to be protected. In doing so two types of protection may be used from HWL+0.50m to toe+1.0m (Horizontal). The protection measure by 400x400x200mm and 400x400x300mm CC block over a geotextile filter (measure‐I) and by gras‐stone as used along embankment side slope (measure‐II) may be used from Tranch‐2 onwards to observe its affectivity. The cost under measure‐I is about BDT 2480.00 per m2 and that under measure‐II is about BDT 1700.00 per m2. In another alternative (measure‐III) grout filled mattress may be placed against wave protection. In that case the cost per m2 for a 0.20m thick grout filled mattress shall be about BDT 3420.00 per m2.
However, it is proposed to provide 2 km of protection under Tranch‐1 as per measure‐I in most vulnerable stretches and another 2 km is proposed under measure‐II to other vulnerable stretches to finalise the applicability of any of the measure under subsequent tranches.
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Appendices
Appendix I: Sample Design Calculation for Bank Protection Works at Chouhali ...... 78 Appendix II: Sample Design Calculation for Regulator at Gala (4V‐ 1.5m x 1.8m) ...... 93 Appendix III: The Preliminary Estimates for Tranch‐1, Tranch‐2 and Tranch‐3 ...... 122 Appendix IV: Design Criteria ...... 131 Appendix V: Road on the Land‐Side of Rehabilitated or Reconstructed Embankment ...... 172 Appendix VI: Comment Matrix ...... 198
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Appendix I: Sample Design Calculation for Bank Protection Works at Chouhali
Design of Bank and Slope Protection Works on left bank of Jamuna River
Name of the Project: Main River Flood and Bank Erosion Risk Management Program(FBERMP) Reach under consideratuin: Chouhali‐Nagarpur in Tangail District.
Note (i): The section of embankment (crest level, side slope, crest width) stated below is proposed as per frequency of hydrological data and stability analysis coducted on proposed embankment section.
Reach / Design under consideration Name of work : Bank protection work in Chouhali‐Nagarpur along the left bank of Brahmaputra‐Jamuna River.
Embankment Crest Level 15.50 m PWD HFL (100 yr): 14.00 m PWD Maxm flood level observed 13.10 m PWD Average HFL 12.20 m PWD LLW observed: 4.50 m PWD Average LWL 5.00 m PWD Average bank level: 11.00 m PWD (From Survey)
Note (ii): The WL (100yr, Highest observed, av.HWL, av.LWL and LLWL) are interpolated WL from the WL gauges at Bangabandhu (Jamuna) Bridge and Aricha. The Ground level is taken fron the survey conducted on the bore‐hole location along the left Bank of the River in the stretch mentioned. The bore‐holes for sub‐soil exploration were conducted by BWDB under the project from November 2011 to February 2012.
DESIGN DATA
Bankfull Discharge of the River (Qb) => 48,000 m3/sec [From FAP‐24, and Design guidelunes FAP‐21 ] 3 100 yr discharge of the River (Q100) 100,000 m /sec 3 Design Discharge of the Channel (Qch) 36,000 m /sec (Design Guidelines) Highest Water Level ‐ Observed (HWL) => 13.10 m PWD Average Low Water Level (LWL) => 5.00 m PWD Average Flow Velocity (V) => 3.00 m/sec Suggested flow velocity is 3.00 m/sec
The design discharge Qch for a channel can be calculated by: 3 Qch = C1/Cb. 2. Qb 36,000 m /sec with C1 = 1.5 (FAP‐21 Guidelines)
Cb = 4 (Braiding index)
Note (iii): Channel Discharge (Qch) is calculated from the 100 yr maximum discharge and the distribution of flow in a channel suggested by Design Guidelines and Manuals (FAP‐21). The ditribution of flow and the selection of design flow (Qch) in the channel is again checked through the results obtained by model study made by IWM in conducting the FS of Nagarpur‐Chouhali Project.
Water Surface Slope => 6.00 cm/km (assumed, WL Gauge record analysis) Average Bed level (near bank) 0.00 m PWD Maxm scour observed ‐3.00 m PWD Average size of river bed materials => 0.18 mm (FAP‐24, and Nagarpur‐Chouhali Protection, IWM)
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Existing Embankt slope River side (V:H) => ( 1 :3) (Field office data) Proposed Slope of Bank to Avg.LWL. => ( 1 :3) Bank slope below av.LWL (V:H) = > ( 1 :2)
Fetch Length => 7.00 km (From Model) Use = 7.00 km Wave Height => 1.30 m (100 yr wave in Jamuna, FAP‐21 Guidelines) Wave period = >2.45sec (Guidelines for River Bank Protection, BWDB‐BUET) Location of vulnerable area in the River => Moderate bend Proposed Length of slope + bank Protection => 5000 m (on the left bank of Jamuna River)
A. Design for size of Revetment Materials :
1.0 Against Velocity and Shear:
A‐1. Using Neill's method
D = 0.034 V2 0.306 m =306mm
Note: Neill's equation uses only the velocity. Other variables for a stream are not considered.
A‐2. Using JMBA equation
Data:
Flow Velocity ( V ) => 3.00 m/sec (Observed data and Guidelines Ratio of water depth and Revetment size (h/D) = 5FAP‐21)
Slope of Bank 1V:3H ( Θ ) => 18.43 ° Angle of Repose of Revetment Materials, CC Block (Φ ) 40.0 °
Sp.Gravity of Revt.Material, cc block ( Ss )=> 2.40 [‐] Acceleration due to gravity (g) => 9.81 m/sec2
2 v 27.0 D n 2 2 5.0 12 log Dhg /1./6 SinSin s s
0.241 m 241 mm
Note (iv): The JMBA equation is developed for cc blocks. In this case for slope protection cc blocks is pro[osed to be used. For bank protection several approach will be tried. However, for this project the JMREMP method, that uses sand filled geobags below LLWL, will be preferred.
Page 79 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
A‐3. Pilarczyk equation
2 0.035u φ K Kh sc Dn Δm g2 Ks Ψcr
Dn = Nominal thickness of protection unit D [m] = size of rock =[m] u = average flow velocity =3.00m/s
∆m = Relative density of submerged material = (ρs‐ρw)/ρw = [‐] 3 ρw = Density of water = 1000 kg/m 3 ρs = Density of stone boulders/Rocks = 2650 kg/m 3 ρs = Density of concrete (stone aggregate), cc block = 2400 kg/m 2 g = accleration due to gravity = 9.81 m/s
φsc = stability factor (for current) = [‐] θ = Angle of repose (rocks) = °
Ψcr = critical shear stress parameter (Shields)= [‐]
Kτ = Turbulance factor = 1.5, for mild outer bends of rivers 1.5 [‐] ‐0.2 Kh = depth factor = (h/Dn+1) = [‐] 2 1/2; Ks = Bank normal slope factor = [1‐(sinα/sinθ) ] (specific material) [‐] α = slope angle of bank structure = 1V:3H (above LWL) 18.43 ° α = slope angle of bank structure = 1V:2H (below LWL) 26.57 ° h/Dn = [‐] h= average water depth ( average depth of water at bankfull stage) 6.00 [m] Dn = Nominal size of protection unit (assumed) = [m] 2 1/2 Ks = [1‐(sinα/sinθ) ] = [‐]
Dn = mmm
Note: (v) Logarithmic velocity profiles exist for long stretches with constant bed roughness. For most engineering works on slope or bottom protection, non‐developed velocity profile is usually present, (Pilarczyk, 2000). (vi) In this case non‐developed velocity profile is considerd.
Non‐Developed Velocity Profile
(1) CC blocks, concrete with stone aggregate (multi‐layer): ‐0.2 Kh = depth factor (for non‐developed vel. profile) = (h/Dn+1) = 0.540 D = nominal size of protection element (assumed) = (cc block) n 0.29 m
Page 80 September 2013 Technical Designs for Tranch‐1 Work
h/Dn = 20.69
∆m = (ρs‐ρw)/ρw = 1.40 [‐] α = slope angle of bank structure = 1V:2H (below LWL) 26.57 ° α = slope angle of bank structure = 1V:3H (at or above LWL) 18.43 ° θ = Angle of repose (cc blocks) = 40 ° 2 1/2 Ks = [1‐(sinα/sinθ) ] = (below LWL) 0.718 [‐] 2 1/2 Ks = [1‐(sinα/sinθ) ] = (at or above LWL) 0.871 [‐]
φsc = stability factor (cc block, randomly placed, multi layer) = 0.80 [‐]
Ψcr = critical shear stress parameter (Shields) = 0.035 [‐]
Dn = 0.296 m = 296 mm (below LWL)
Dn = 0.244 m = 244 mm (at or above LWL)
(2) Rocks: ‐0.2 Kh = depth factor (for non‐developed vel. profile) = (h/Dn+1) = 0.529
Dn = nominal size of protection element (assumed) = (cc block) 0.26 m
h/Dn = 23.08
∆m = (ρs‐ρw)/ρw = 1.65 [‐] α = slope angle of bank structure = 1V:2H (below LWL) 26.57 ° α = slope angle of bank structure = 1V:3H (at or above LWL) 18.43 ° θ = Angle of repose (rocks) = 35 ° 2 1/2 Ks = [1‐(sinα/sinθ) ] = (below LWL) 0.626 [‐] 2 1/2 Ks = [1‐(sinα/sinθ) ] = (at or above LWL) 0.834 [‐]
φsc = stability factor (broken riprap and boulders) = 0.75 [‐]
Ψcr = critical shear stress parameter (Shields) = 0.035 [‐]
Dn = 0.264 m = 264 mm (below LWL)
Dn = 0.198 m = 198 mm (at or above LWL)
(3) CC blocks, concrete with stone aggregate, hand placed/single layer h = depth of water infront of hand placed cc blocks revetment =4.00m ‐0.2 Kh = depth factor (for non‐developed vel. profile) = (h/Dn+1) = 0.497
Dn = nominal size of protection element (assumed) = (cc block) 0.13 m
h/Dn = 32.00
∆m = (ρs‐ρw)/ρw = 1.40 [‐] α = slope angle of bank structure = 1:3 (above DLW) 18.43 ° θ = Angle of repose = 40 ° 2 1/2 Ks = [1‐(sinα/sinθ) ] = 0.871 [‐]
φsc = stability factor (application type) = 0.65 [‐]
Ψcr = critical shear stress parameter (Shields) 0.05 [‐] D = n 0.128 m = 128 mm
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(4) Geo‐textile bags (sand filled geobag) ‐0.2 Kh = depth factor (for non‐developed vel. profile) = (h/Dn+1) = 0.569
Dn = nominal size of protection element (assumed) = (A1‐type bag) 0.38 m h/Dn = 16 3 ρs = Density of sand bag = 1800 kg/m 3 ρw = Density of water = 1000 kg/m
∆m = (ρs‐ρw)/ρw = 0.80 [‐] α = slope angle of bank structure = 1:2 (below DLW) 26.57 ° θ = Angle of repose (geobags) = 30 ° 2 1/2 Ks = [1‐(sinα/sinθ) ] = 0.447 [‐]
φsc = stability factor = 0.50 [‐]
Ψcr = critical shear stress parameter (Shields), gabions 0.05 [‐]
Dn = 0.383 m = 383 mm
Recommendation: Recommended size against velocity is = 125 kg
Equivalent thickness of bags = (abc)1/3 3 Type Wt (kg) Vol (m ) Eq. Dn A3‐type 250 0.167 551 mm (Equivalent block size) A4‐type 175 0.117 489 mm (Equivalent block size) A5‐type 125 0.083 438 mm (Equivalent block size) B2‐type 78 0.052 373 mm (Equivalent block size)
Unit weight of sand= 1500 kg/m3
A‐4. Using Corps of Engineers Relationship (Maynord's Equation, 1991):
2 .1 25 D V Y CCCS TvSf 1 ygs k1
(the formula has been developed for rocks)
where;
D = nominal rock size = D30 = (m) V = Local depth averaged flow velocity = 3.0 m/s Y = local depth near the bank = 6.0 m
Sf = Safety factor = 1.2 (‐)
Cs = Stability coefficient = 0.30 (‐)
Cv = Vertical velocity distribution coeficient = 1.1 (‐)
CT = Thickness coefficient = 1.2 (‐) s = dry rock density =2.65(‐)
K1 = side slope factor = 1V:2H = 0.9 (‐)
K1 = side slope factor = 1V:3H = (above Low Water Level) 1.0 (‐) 2 g = accleration due to gravity = 9.81 m/s
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D =D30 = 0.166 m 166 mm (on 1V:2H slope)
D50 = 0.208 m 208 mm
D =D30 = 0.146 m 146 mm (on 1V:3H slope)
D50 = 0.182 m 182 mm
The nominal size D30 may be conveted to a mean diameter D50 by using the equation 1/3 1/3 D50 = D30x(D85/D15) , where (D85/D15) is equql to 1.25 for tyical well graded riprap.
Note (vii). (a) D50 is typically about 25% larger than D30,(b) V is the depth averaged velocity at a point inshore from the slope (c) Y is the local flow depth, rock size given by the formula is relatively sensitive to depth, it is more
conservative to underestimate the depth, (d) minimum value for safety factor (Sf) is 1.1, higher value is suggested
where there is ice or debris impact, (e) suggested values for Cv (vertical velocity distribution factor) for straight channels are 1, and 1.25 at downstream of concrete lined sections and at the end of dykes, (f) values for stability
co‐efficient Cs is 0.30 for angular rock and 0.36 for rounded rock. (g) basic value for thickness co‐efficient CT is
1xD100 or 1.5xD50, whichever is higher, (h) recommended values for side slope factor K1 is = 1, for slope 1V:3H or
flatter, K1 = 0.9 for slope 1V:2H, K1 = 0.8, for slope 1V:1.75H, and K1= 0.7 for slope 1V:1.5H.
2.0 AGAINST WAVE:
Fetch Length => 7.00 km Wave Height ( Hs ) => 1.30 m (Guidelines for Bank Protection, Wave Period (Tm) => 2.45 sec BWDB‐BUET) Slope of Bank 1V:3H ( θ ) => 18.43 ° Specific gravity of protection materials, rock (Ss)= 2.65 [‐] Specific gravity of protection materials, cc block (Ss)= 2.40 [‐]
A‐5. Using Pilarczyk Equation :
b Hs ξ z Dn cosα um ΦΨΔ sw
Dn = Revetment material size (single unit) [m] [m]
Hs = significant wave height [m] 1.30 m 3 ρw = Density of water = 1000 kg/m 3 ρs = Density of rocks = 2650 kg/m 3 ρs = Density of concrete (stone chips, cc block) = 2400 kg/m
∆m = Relative density of submerged material = (ρs‐ρw)/ρw = [‐] g = accleration due to gravity [m/s2]= 9.81 m/s2
Ψu = system specific stability upgrading factor = [‐]
Φsw = stability factor for wave loads, hard rocks [‐] = [‐] α = slope angle of bank structure = 1:3 = 18.43 °
Page 83 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
ξz = wave similarity parameter [ tanα.(1.25Tm/Hs^0.5) 0.90 [‐]
Tm = mean wave period [s] = 2.45 secs b = wave structure inter action coefficient =[‐]
Protection Element Dn = m ≈
(1) CC blocks with stone aggregate as protection element (CC blocks, cubical shape, hand placed in single layer)
Ψu = system specific stability upgrading factor [‐] = 2.00 [‐]
Φsw = stability factor for wave loads [‐] = 2.25 [‐] b = wave structure inter action coefficient [‐] =0.87[‐]
∆m = Relative density of submerged material = 1.40 [‐]
Dn = 0.198 m ≈ 198 mm
(2) CC blocks cubical shape, randomly placed multi layer
Ψu = system specific stability upgrading factor [‐] = 1.40 [‐]
Φsw = stability factor for wave loads [‐] = 2.50 [‐] b = wave structure inter action coefficient [‐] =0.50[‐]
∆m = Relative density of submerged material = 1.40 [‐]
Dn = 0.265 m ≈ 265 mm
(3) Broken rocks/boulders, randomly placed
Ψu = system specific stability upgrading factor [‐] = 1.33 [‐]
Φsw = stability factor for wave loads [‐] = 2.50 [‐] b = wave structure inter action coefficient [‐] =0.50[‐]
∆m = Relative density of submerged material = 1.65 [‐]
Dn = 0.236 m ≈ 236 mm
In using CC block (hand placed) for slope protection (above LLW), two rows of 400x400x200 mm cc blocks followed by one row of 400x400x300 mm cc blocks will be placed on slope alternately. In consideration of wave height the required block thickness (>198mm) can be satisfied with the size 400x400x200 mm. The minimum thickness used by BWDB is 200 mm. Recommended thickness of block is = 200 mm
The protection is considered seperately for (i) the embankment slope from toe to crest level or upto HHWL (ii) upper part; of bank slope (from Design low water level (DLWL) to the top of existing bankline or Flood Plain Level (FPL), and (iii) areal coverage of underwater slope and falling apron/launching apron to protect the lower portion of bank section against vertical scour induced by stream flow.
3.0 Size of Protection Element
3.1 Size of Protection Element for upper slope (above LWL)
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3.1.1 Size of Hard rock as Protection Element (above LWL)
The element size (hard rock) for the upper slope (above LWL) by Pilarczyk formula is 198 mm (at or above LWL) against flow velocity and 236mm againt anticipated wave (Hs = 1.30m). By USACE formula the element size on 1V:3H is 182 mm.
Recommended size :Dn =200mm
Approximate gradation of pitching stone shall be as below:
Minimum 40% of the stone shall be in the range of 200 mm to 300 mm, 60% will be 300 mm to 400 mm.
3.1.2 Size of CC block as Protection Element (above LWL)
Required thickness of hand placed cc block by Pilarczyk formula against velocity is 128 mm, and that against wave is 198mm. The dominant size in this case (hand placed cc block) is 198 mm.
Recommended (thickness) of cc block =200mm
3.2 Size of Protection Element for protection for lower slope (below av.LWL)
3.2.1 Size of Rock as Protection Element (below LWL)
The size of protection element for stability against stream flow velocity is 264 mm by Pilarczyk equation and 208 mm by USACE equation. so the higher size from both the equation is recommended for protection of lower slope (bank slope below av. LWL). D50 size of protection element is 264mm. Shall not be less than 260mm; recommended size is 260mm.
Dn =260mm Size of 40% of the rocks will be in the range of 200 mm to 300 mm and 60% of the rocks will be in the range of 300 mm to 400mm.
3.2.2 Size of CC Block as Protection Element (below LWL)
The size (thickness) of protection element, (randomly placed cc block) by Pilarczyk equation is 296 mm and that by JMBA equation is 241 mm. In this case the higher size of protection element through both the equation may be selected as protection element. Minimum size (thickness) of cc block is therefore, 296 mm.
The size with standardization is selected as =300mm
3.2.3 Size of geobag as protection Element (below LWL)
The size (thickness) of protection element, (randomly placed geobag) by Pilarczyk equation is 383 mm against flow velocity. The recommended size is 125 kg (geobag), equivalent thickness is 438mm.
Recommended size of geobags is 125 kg Equivalent thickness 438 mm
Page 85 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
4.0 Summary for Pitching Thickness (T):
A. Riprap thickness:
(i) U.S. Army Corps of Engineers (1991), recommends that thickness of protec on should not less then th spherica diameter of the upper limit W100 (percent finer by weight) stone or less than 1.5 times the spherical diameter of the
upper limit W50 stone, whichever results in greater thickness.
(ii) California Highway Division (1991) recommended that there should be at least twolayers of overlapping stones so that slight loss of materials does not cause massive failure.
(iii) ESCAP (1973) recommends that the thickness of protection should be at least 1.5D, where D is the diameter of the normal size rock specified.
(iv) Inglis (1949) recommended following formula to compare thickness of protection required on the slope of revetment:
Where, t (m) = thickness of stone riprap and Q (m3/s) is Discharge Note: the Inglis formula apparently gives excessive thickness for higher discharge.
(v) Indian Standard : (IS 14262 : 1996)
Minimum thickness of protection layer is required to withstand the negative head created by velocity. This may be determined by the following relationship:
Where, T = thickness of protection layer in m V = velocity in m/s g = accleration due to gravity (m/s2) and Ss = Specific gravity of stones
For safety purposes, two layers of stones according to the size obtained in 3.4 above should be provided.
The formula results in T= 0.278 m 278 mm
Since the thicknes should not be less than 2 layers, so the recommendation by Califotrnia Highway may be accdepted for the design i.e. T=> 2D.
Page 86 September 2013 Technical Designs for Tranch‐1 Work
(vi) Using Inglish formula : T= 0.06 Q1/3 = 7.120 ft = 2170 mm
(vii) According to Spring, on the basis of river slope & river bed Materials :
River bed Remarks materials Thickness in inches for river slope in classified inches per mile by Spring 9121824 Very coarse 19 22 25 28 Coarse 25 28 31 34 Medium 31 34 37 40 Fine 37 40 43 46 Very fine 43 46 49 52
River Bed Materials assumed=> Very fine River Slope considered => 3.80 inch/mile From Chart, Thickness T => 31 inch = 787.4 mm
(viii) According to Gales , on the basis of discharge:
River Discharge from 0.25 Q' from 0.75 to Q' from to 0.75 million 1.50 million cusecs 1.5 to 2.5 Body and Body and million Head Parts of Guide Bund Head tail tail Head Pitching Stone 3'‐6'' 3'‐6'' 3'‐6'' 3'‐6'' 3'‐6'' Thickness of soling bal 7'' 7'' 8'' 8'' 9'' Total thickness 4'‐1'' 4'‐1'' 4'‐2'' 4'‐2'' 4'‐3''
Discharge of the River ( Q ) => 1,270,352 Cusec From Chart, Pitching Thickness ( T ) => 3'‐6" 3.50 ft 1067 mm
A‐1. Thickness of Protection (Upper slope, slope above LWL)
(a) Based on Stone Size: (i) U.S. Army Corps of Engineers
T = 1.5xW50 = 300 mm (minimum)
(ii) California Highway Division T = 2xD = 400 mm
(iii) According to ESCAP T = 1.5xD = 300 mm
(iv) Indian Standard T = 2D = 400 mm
Page 87 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
(b) Based on Stream flow properties
As per Inglish, T = 2170 mm As per Spring, T = 787 mm As per Gales, T = 1067 mm A.1.1 Thickness of Rock as Protection Element (above LWL)
Considering major eroding forces and other characteristics of the river the minimum thickness suggested by size of protection element appears reasonable for pitching. As therel wil be filter below the pitching, so the thickness suggested by recent practices on size of protection material, appears to be justified.
the thicknes of prtection should not be less than 2 layers of protection element, so the recommendation by California Highway Division may be accdepted for the design i.e. T=> 2D.
Above LWL protection thickness, T= 400 mm
Filter: Under the pitching a filter fabric (minimum 3mm thick geotextile filter) shall be provided from top of bank to at least 1 m below LWL. Below the filter fabric 100 mm thick sand (FM≥1.0) shall be placed with proper compaction.
A.1.2 Thickness of CC block as Protection Element (above LWL)
The thicknes of cc block above low water is 128 mm (hand placed) against flow velocity and that against wave is 198mm. The higher thickness of the two i.e. the thickness required against wave is selected for the protection. Recommended thickness of cc block is. 200 mm
Thickness of stone (minimum 2 layers) on slope (1V:3H) above LWL, against significant wave is 400 mm. But against the same wave height, the thickness of hand placed cc block is 198 mm (Pilarczyk equation). The cc blocks can also be arranged in different sequence for breaking waves more eficiently.
So cc blocks of size 400x400x200 mm (2 rows) and 400x400x300 mm (1 row) is proposed to be placed over the slope up to bank level+1.50m horizontal on flood plan and keyed to the flood plain.
Protrussion on a slope is observed to be more efficient than a rough slopeg for breakin wave. In that consideration cc block can be more effectively arranged to create sudden protrussion. With that aim CC block, stable against anticipated wave height is recommended to be used on bank and embankment slope.
A‐2. Thickness of Protection (Lower slope, bank slope below LWL)
(a) Based on Stone Size: (i) U.S. Army Corps of Engineers
T = 1.5xW50 = 390 mm (minimum)
(ii) California Highway Division T = 2xD = 520 mm
Page 88 September 2013 Technical Designs for Tranch‐1 Work
(iii) According to ESCAP T = 1.5D = 390 mm
(iv) Indian Standard T = 2D = 520 mm
(b) Based on Stream flow properties
As per Inglish, T =2170mm As per Spring, T =787mm As per Gales, T =1067mm
A.2.1 Thickness of Hard Rock as Protection Element
Considering flow velocity as major eroding force and other characteristics of the river the minimum thickness suggested by size of protection element (hard rock) appears reasonable for dumping. As the protection material will be dumped under water, so the thickness of dumping need to be 50% more than that required for pitching. the thicknes of prtection should not be less than 2 layers of protection element, so the recommendation by Califotrnia Highway Division may be accdepted for the design i.e. T=> 2D.
Thickness of pitching required above water (placing) = 2D = 520 mm
Below LWL protection thickness, T= 780 mm (50% additional due to under water dumping)
For protection below LWL use of hard rock as protection element is the most sustainable solution. Being very costly and scarcity of stone in Bangladesh, cc block as protection element (below LWL) is calculated as alternative protection element.
A.2.2 Thickness of CC Block as Protection Element (below LWL)
Size of CC block (protection element) against flow velocity is Dn =300mm Considering minimum thickness of protection element below LWL (as in case of rock) as 2D+50% additional (for under water dumping), the thickness of protection becomes = 2.5D = 750 mm However, in case of using cc block the minimum thickness should be 3D (considering winnowing effect) +50%.
The suggested thickness is therefore, 4.5 D = 1350 mm
For protection below the LLWL project intends to use geobag as practiced in JMREMP. A LWL berm shall be made at El, +3.00 m PWD (width about 5.0 m). The slope from av LWL (+ 5.0 m PWD) to the river side end of LWL berm (+3.0m PWD) shall be protected with two layers of 300mm cube cc blocks over geotextile efilter and on layer of geobag (125kg).
A.2.3 Thickness of Geobag as protection Element (below LWL)
Size of geobag as protection element against flow velocity is 125 mm Equivalent thickness is =438mm
Actual size of 125 kg geobag is 930x530x170 mm, L =930mmB =530mmt =170mmArea =0.49m2 Suggested actual thickness is =0.17m
Page 89 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
5.0 Design of areal coverage and Launching Apron: Assumed: (1) Apron will launch in 1V: 2H slope. (2) A multiplication factor will be used as per river bend condition.
Table ‐B (Emperical multiplying factors for Data: maxm scoure depth) Design Discharge ( Q) => 36,000 m3/sec (Jamuna Left Channel) Highest Water Level (HWL) => 13.10 m new PWD Nature of location Factor Av. Low Water Level (av.LWL) =5.00m new PWD Straight reach of channel 1.25 River bed level at flatter slope 0.00 m new PWD Moderate Bend 1.50 (assumed av. River bed level) Severe Bend 1.75 Maximum Observed Scour = ‐3.00 m new PWD Right angle or abrupt turn 2.00 Size of av.Bed material (dm) 0.18 mm Noses and Piers 2.00 Silt factor, f = 1.76 (dm)1/2 0.75 Alongside Cliff and Walls 2.25 Noses of Guidebanks 2.75
Note: scour depth for the river is not available. Rather the channel discharge and size of bed material is available from different sources (FAP‐24 and Nagarpur‐Chouhali FS). So in this case theoretical scour calculation appear to be more reliable. The x‐sections are availabler fo only one observation, which is not completely dependable for scour calculation.
Scour 1/3 Regime Depth; R = 0.47 (Q/f) = 17.11 m The eroding area situated on a moderate bend, so scour depth = R*1.5 = 25.66 m Say 26.00 m Maximum depth of Scour (scour Level) = ‐12.90 m PWD Apply ‐13.00 m
Calculations: (materials for bank protection)
The areal coverage shall be placed from av.LWL (+3.0 m PWD) to a level of 0.00 m PWD. Length of areal coverage shall be 30.00 m. The falling apron/launching apron material is proposed to be placed at the end of areal/slope coverage. The length of launching apron shall be 15.00 m:
Ds = Depth of scour = Av. River bed level ‐ scour level = 13.00 m
Length of launching apron = 1.5xDs = 19.50 m say 20.00 m (Theoretical)
The falling apron is proposed to be placed at the end of areal coverage i.e. on reasonably flat bed. The areal coverage will be placed from av.LWL (+3.0m PWD) to av. river bed level (0.0m PWD). Length of areal coverage shall be 30.0m.
The length of slope surface from (+3.0m) to av. River bed (0.00 m PWD) is 6.71 m (bank slope below +3.00 is 1V:2H) The distance along the desired slope surface (slope 1V:2H) from LWL berm to average river bed level (from +3.0m to 0.0 m PWD) is 6.71 m The theoretical launching apron length is = 20.00 m Minimum coverage needed = 26.71 m
So the length of areal coverage (30 m) and additionally 15.0 m launching apron takes care of all uncertainties including abnormal scour. The 30.0 m areal coverage is proposed in line with work done under JMREMP in PIRDP area.
Page 90 September 2013 Technical Designs for Tranch‐1 Work
Recommended stretch of protection after the LWL Berm
Areal Coverage 30.0 m Launching Apron 15.0 m
I. Using hard rock as Protection element for Bank Protection
Thickness of hard rock (pitching) = T = 520 mm Thickness of hard rock below LWL = T1 = 1.5T= 780 mm Thickness at end of areal cover = T1 =1.5T = 780 mm
3 Volume of rock from av. GL (+11.0 m to 5.0 m PWD) to av. LWL 11.95 m /m Av. LWL to River side end of berm (5.0m berm) below LWL 8.83 m3/m Volume of rock from LWL berm to av. River bed level = 23.40 m3/m Volume of rock as apron (15.0m) 11.70 m3/m Total element for bank protection per m 55.88 say 56.00 m3/m
II. Using cc block above av.LWL, on Transition (LWL Berm to av.LWL) and geobag below LWL
Thickness of cc block (pitching) = T = 200 mm (above LWL, hand placed over a geotextile filter) Thickness of cc block (pitching) = T = 300 mm (above LWL, hand placed over a geotextile filter) Size of cc block below LWL = D = 300 mm (coverage, on LWL berm and slope above berm) Thickness of 125 kg beobag 0.17 m Thickness of areal cover (geobag)= 3t= 0.51 m (125 kg geobag, thickness = 0.17m)
Volume of cc blocks 3 From av. GL (+11.0 m to + 5.00 m PWD) to av. LWL 4.42 m /m (slope 1V:3H) 3 From av. LWL to berm (5.0 m) below LWL =6.79m /m (300 mm cube, 2 layers) 3 (200 mm and 300mm thick) on flood plain (2.4m +2.0 m below Flood plain) 0.88 m /m Total cc blocks (400x400x200 mm and 300 mm cube) 12.10 m3/m Adopt 12.10 m3/m
3 Volume of geobag (1 layer) on LW berm and slope from Berm to LWL 1.93 m /m Volume of geobags (3 layers) as areal coverage (30.0 m)+33% 20.35 m3/m Volume of geobags (3 layers) as launching apron (15.0 m)+33% 10.17 m3/m 3 3 Total geobags (125 kg) as areal covrage+ launching apron 32.45 m /m Adopt 32.40 m /m
Design Recommendation
(i) The section under considerstion shall be modified to create a LWL berm. A berm (5.0 m wide) shall be made at about El. 3.0 m PWD, the bank slope above that (about 3.00 m to 11.0m PWD) shall be prepared in a slope of 1V:3H.
Page 91 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
(ii) Bank protection (for about 5000m) with cc block (thickness 200 mm ) is recommended. The reach of protection mentioned shall be reviewed with cross‐section measured along the affected reach before execution of the protection work.
(iii) Geotextile filter (thickness>=3.0mm, needle punched) shall be placed below the cc block on slope, and LWL berm over minimum 100 mm thick compacted sand (FM>1.5) cushion (above LWL). The geotextile filter shall be extended at least 1.0 m beyond the LWL berm at the lower end and 1.5m beyond the cc block on flood plain.
(iv) The berm below LWL and the slope from berm to av.LWL (+3.00 m PWD to +5.0 m PWD) shall be protected with 2 (two) layers of cc block (300 mm cube) dumped over one (1) layer 125 kg geobag placed over the geotextile filter.
(v) The bank section from outer end of LWL berm (for an width of about 30m) shall be covered with minimum 3 (three) layers of 125kg geobags, dumped from a properly positioned and anchored barge.
(vi) At the outer end of areal coverage a launching apron (15.0 wide) shall be prepared with minimum 3 layers of 125 kg geobags dumped from a properly positioned and anchored barge.
(vii) The coverage of minimum 3 layers of geobag shall be ensured through provision of an additional one layer of geobags i.e. 33% extra over the designed thickness.
(viii) The protection work shall be performed in the sequence as (a) areal coverage, (b) LWL berm and slope preparation and coverage by designed element and filter, © Launching apron, and (d) flood plain cover as per design.
Page 92 September 2013 Technical Designs for Tranch‐1 Work
Appendix II: Sample Design Calculation for Regulator at Gala (4V‐ 1.5m x 1.8m)
Design Data Name Of Project: Main River Flood and Bank Erosion Risk Management Program Name of Sluice: Drainage Sluice at Gala, Kaizuri (Regulator # 3) Location: Gala Boral/Hurasagar Size: 4V‐1.5mx1.8m
3Embankment type: Composite Section with road at side (a) Crest Level: 15.60 m PWD (b) Road Level: 14.10 m PWD (b) Crest width: 16.20 m © Side Slope: R/S (1V:xH) 1 3.0 C/S (1V:xH) 1 2.5 4(a) Highest Water Level (100 yr): 14.10 m PWD (100 yr) (b) Highest WL (observed) 13.70 m PWD © Av. HWL 12.40 m PWD (d) Lowest Water Level (LLW) 4.50 m PWD (e) Av. Low Water level (av.LWL) 5.20 m PWD (f) Av. WL (April, 15‐30) 6.81 m PWD (g) Av. WL (May, 1‐15) 7.50 m PWD (h) Av. WL (October, 15‐31) 9.40 m PWD (i) Av. WL (November, 1‐15) 8.12 m PWD
5Drainage area: 3550 ha 6 Lowest Basin Level 8.50 m PWD 7Av. ground level around structure 10.50 m PWD 8Bottom Level of drainage channel m PWD (near outfall)
10 Angle of Internal Friction of soil (φ)20.00°
Page 93 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
SIZING OF REGULATOR/SLUICE (NON TIDAL)
Name of sub‐project : Main River Flood and Bank Erosion Risk Management Program Upazila : Shahzadpur District : Sirajganj Name of Regulator/Sluice : Drainage Sluice at Gala, Kaizuri (Regulator # 3) Size: 4V‐1.5mx1.8m
Flow Considerations: 0.5 When Hw > Hv and Htw > Hv , Flow Type IQI = 0.80xNxBwxHvx(2x9.81xh') 0.5 When Hw > 1.5Hv and Htw < Hv , Flow Type III QIII = 0.60xNxBvxHvx{2x9.81x(Hw‐Hv/2)} 0.5 When Hw < 1.5Hv and Htw >2Hv/3 , Flow Type IV QIV = 0.83xNxBvx(Hw‐h')x(2x9.81xh') 3/2 When Hw < 1.5Hv and Htw <2Hv/3 , Flow Type VQV = 1.56xNxBvxHw
Where: Hw = Upstream Water Depth N = Vent Nos.
Htw = Tail Water Depth h' = Head Difference
Hv = Vent Hieght Q = Flow through Regulator
Bv = Vent Width
Input Data: N = 4 nos. RWL 7.50 mPWD
BV = 1.50 mBasin WL = 8.50 mPWD 3 HV = 1.80 mDesign Q = 14.79 m /Sec Sill Level = 7.00 mPWD
RWL HW HTW h' Flow Type Q (mPWD) (m) (m) (m) m3/Sec
7.5 1.50 0.50 1.00 V 17.20 17.20 OK
Catchment Area = Subproject area : 3550 ha Drainage area outside 0ha
Total 3550 ha
Drainage rate ( Monsoon) =30mm/day Discharge = 12.33 cumec For structure dischage adding 20% 14.79 cumec
Total = 14.79 cumec
Capacity of Regulator to drain = 16.25%
Provide: 4Vent‐1.50m x 1.80m ; Sill Level: 7.00 m pwd
Page 94 September 2013 Technical Designs for Tranch‐1 Work
Name of Project: Main River Flood and Bank Erosion Risk Management Program Regulator/Structure: Drainage Sluice at Gala, Kaizuri (Regulator # 3) District: Sirajganj DRAINAGE MODE Size: 4V-1.5mx1.8m
OUTLET (D/S) STILLING BASIN DESIGN R/S REQUIRED INPUT DATA
Design U/S Water Level --> 8.50 m from field data 5 Design D/S Water Level --> 7.50 m from out fall river level analysis. (Mean low water Level/ tide level ) No. of Vents --> 4 Inside Barrel Height (Hb)--> 1.80 m [Pre-monsoon drainage is assumed Inside Barrel Width (Bb) --> 1.50 m for 1st fortnight of May] Barrel Invert Level --> 7.00 m PWD Distance between abutments (Ba) 7.80 m
D/S Basin Invert Level --> 6.00 m, PWD U/S Basin Invert Level --> 6.50 m, PWD Gate Clearance Side (Cs) --> 0.00 m Gate Clearance Bottom(Cb) -> 0.00 m Glacis Length (Gl) --> 3.00 m Basin Flare Angle (ø) --> 7.50 ° Pier Thickness 0.60 m Protective Apron Side Slope; (Ss) --> (1 : 2.00 ) Vertical:Horizontal Ground Level (near Structure) 10.50 m
U/S 8.50
D/S
7.50 1.80 7.00 0.00 6.00 //\\//\ //\\//\ 3.00 Barrel Glacis Basin
STRUCTURE SECTION
STRUCTURE PLAN Protective Appron side Slope1: 2.0
7.50 ° 0.00
1.50 Protective 7.80 Pier Glacis Basin Apron
Page 95 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
Final Result Drainage Sluice at Gala, Kaizuri (Regulator # 3) Size: 4V‐1.5mx1.8m DRAINAGE MODE
Total discharge = 17.20 m³/sec Flow Condition= 5
Basin Level adjacent to Barrel 7.00 m PWD Basin Level (D/S) 6.00 m PWD
Critical depth (dc) =0.94m Value of d1 =0.31m Subsequent d1 =0.31m
Froude no (F1) =3.78 Basin Type: Indian Standard Stilling Basin I
TWD (available) =1.50m TW min 1.49 m Value of d2 =1.49m
Length of Jump =6.85m Glacis Length (Gl) =3.00m Use basin length (L) = 8.50 mValue of X =1.48m Value of X used =1.50m Flaring angle 7.50 ° Height of Chute =0.31m Vale of B3 = 10.80 m Used value =0.50m Velocity V3 =0.83m/sec Value of A3 20.70 m²
Silt Factor =0.68 Scour depth (Regime) = 2.08 m
U/S scour depth =2.60m D/S scour depth =3.12m
U/S cut off wall= 0.60 m Use 3.00 m D/S Cut‐off wall= 1.63 m Use 4.00 m
C/S block Prot. = 3.00 m Use 5.00 m C/S Loose apron = 4.50 m Use 5.00 m
R/S Block Prot.= 6.00 m Use 6.00 m R/S Loose apron =6.00mUse 6.00 m
Page 96 September 2013 Technical Designs for Tranch‐1 Work
Name of Project: Main River Flood and Bank Erosion Risk Management Program Regulator/Structure: Drainage Sluice at Gala, Kaizuri (Regulator # 3) Size: 4V‐1.5mx1.8m District: Sirajganj FLUSHING MODE INLET (U/S) STILLING BASIN DESIGN C/S REQUIRED INPUT DATA
Design U/S Water Level ‐‐> 8.00 m from field data 5 Design D/S Water Level ‐‐> 9.00 m from out fall river level analysis. (Mean low water Level/ tide level ) No. of Vents ‐‐>4 Inside Barrel Height (Hb)‐‐>1.80m Inside Barrel Width (Bb) ‐‐>1.50m Barrel Invert Level ‐‐>7.00m PWD Dist.between box Abutments(Ba)‐>7.80m
D/S Basin Invert Level ‐‐>6.00m, PWD U/S Basin Invert Level ‐‐> 6.50 m, PWD Gate Clearance Side (Cs) ‐‐> 0.00 m Gate Clearance Bottom(Cb) ‐> 0.00 m Glacis Length (Gl) ‐‐>1.50m Basin Flare Angle (ø) ‐‐> 7.50 ° Thickness of pier 0.60 m Protective Apron Side Slope; (Ss) ‐‐> (1 :2.00) Vertical:Horizontal Ground Level (near structure) 10.50 m PWD
D/S 8.00
U/S
9.00 1.80 7.00 0.00 6.50 //\\//\ //\\//\ 1.50 Barrel Glacis Basin
STRUCTURE SECTION
STRUCTURE PLAN Protective Appron side Slope1: 2.0
7.50 ° 0.00
1.50 Protective 7.80 Pier Glacis Basin Apron
Page 97 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
Final Result Drainage Sluice at Gala, Kaizuri (Regulator # 3) Size: 4V‐1.5mx1.8m FLUSHING MODE
Total discharge (Qd)= 26.47 m³/sec Flow Type =5
Level Adjacent to Barrel 7.00 m PWD Basin Level (U/S) 6.50 m PWD
Critical depth (dc)= 1.25 m
Value of d1 = 0.54 m
Subsequent d1 = 0.52 m
Froude no (F1) = 2.76 Basin Type: Indian Standard Stilling Basin I
TWD (available) =2.00m TW min 1.78 m
Value of d2 = 1.78 m
Use co‐efficient= 1.00 Indian Standard Stilling Basin I
Length of Jump =6.80m Glacis Length (Gl) ‐‐> 1.50 m Use basin length (L) = 8.50 mValue of X =1.78m Value of X used =1.80m Flaring angle 7.50 ° Height of Chute =0.52m Vale of B3 = 10.40 m Used value =0.50m
Velocity V3 = 0.92 m/sec
Value of A3 28.80 m²
Silt Factor (f) =0.68
Scour depth (Regime) = 2.84 m
U/S scour depth =3.55m D/S scour depth =4.26m
U/S cut off wall= 1.05 m Use 3.00 m D/S Cut‐off wall= 2.47 m Use 4.00 m
C/S block Prot. = 3.00m Use 5.00m C/S Loose apron = 4.50m Use 5.00m
R/S Block Prot.= 6.00 m Use 6.00 m R/S Loose apron =6.00mUse 6.00 m
Page 98 September 2013 Technical Designs for Tranch‐1 Work
NANE OF PROJECT: Main River Flood and Bank Erosion Risk Management Program Name of Structure: Drainage Sluice at Gala, Kaizuri (Regulator # 3) Sirajganj Size: 4V-1.5mx1.8m 2.0 STRUCTURAL ANALYSIS OF BARREL
2.1 REQUIRED INPUT DATA
Embankment Crest Level --> 15.60 m PWD Road Level (inside) --> 14.10 m PWD Embankment Crest width 16.20 m Top slab level= Top Slab Level --> 9.25 m PWD = Invert levl+Vent ht+Top slab thick 9.25 m PWD Maximum Water Level (monsoon) - 14.10 m PWD Maximum Water Level --> 9.50 m PWD Operating Deck Level =Max WL+0.5 (maintenance period) 14.50 m PWD Operating Deck Slab level 14.50 m PWD Live Vehicle Loading(H10 or H20) -> H20
Unit Weight of Steel --> 77.00 KN/m³ Unit Weight of Concrete --> 23.60 KN/m³ Unit Weight of Soil --> 18.90 KN/m³ Unit Weight of Water --> 9.81 KN/m³
Angle of Internal Friction (ø) --> 20 ° Coeff. of Active Earth Pressure (Ca) = (1-sinø) = 0.66
Top Slab Thickness --> 450 mm Bottom Slab Thickness --> 500 mm Embankment side slope Abutment Top Thickness (Barrel)--> 450 mm (a) R/S, 1V:xH 1 2.5 Abutment Bottom Thickness (Barrel)- 500 mm (b) C/S; 1V:xH 1 3.0 Pier Thickness --> 600 mm
No. of Vents --> 4 Inside Height of Barrel --> 1.80 m Inside Width of Barrel --> 1.50 m Invert Level 7.00 m PWD Length of Barrel --> 20.00 m Length of Barrel = 20.00 m Barrel Ext.Length (C/S) --> 1.80 m Barrel Ext.Length (R/S) --> 1.80 m
STRUCTURAL DESIGN OF BARREL
Ultimate Flexural Strength of Steel (fy) --> 4.14E+05 KN/m² 60,044 psi Ultimate Flexural Strength of Concrete(fc') 2.20E+04 KN/m² 3,191 psi
Allowable Flexural Strength of Steel (fs) = 0.45* fy = 1.86E+05 KN/m² Allowable Flexural Strength of Concrete(fc) = 0.4* f'c = 8.80E+03 KN/m²
Allowable Shear Stress of Concrete(v) = 2.89*(fc')^0.5 = 4.29E+02 KN/m²
Modulus of Elasticity of Steel (Es) --> 1.96E+08 KN/m² Modulus of Elasticity of Concrete (Ec) --> 1.98E+07 KN/m²
Coverage + 1/2 Dia.Reinforcement (c) --> 75 mm
SCHEMATIC VIEW OF BARREL 15.60 m \\\///\\\///\\\/// 450 mm 9.25 m
450 mm
1.80 m
500 mm 500 mm 600 mm |:: 1.50 m
Page 99 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
Drainage Sluice at Gala, Kaizuri (Regulator # 3) Size: 4V-1.5mx1.8m STRUCT2 : DESIGN ABSTRUCTS
STRUCTURAL ANALYSIS OF BARREL
TOP SLAB Design Moment M = 48.83 KNm Reqd. depth dr(mom) = 197 mm Design Shear V = 138.87 KN Reqd. depth dr(shear) = 324 mm Reqd.Thickness tr = 399 mm Provided thickness ta = 450 mm
SHRINKAGE REINF (top slab).
Ast (reqd. exp.face) = 950 mm² Ast (provided) Bar dia. (ø) = 16 mm Bar spacing c/c = 200 mm Ast (Actual) = 1005 mm² Ast(reqd, earth face) 570 mm² Ast provided Bar dia. (ø) = 12 mm Bar spacing c/c = 175 mm Ast (Actual) = 646 mm²
TOP REINF (Top Slab).
Ast (mom.) = 782 mm² Ast (shrinkage) = 380 mm²
Ast (provided) 782 mm² Bar dia. (ø) = 16 mm Bar spacing c/c = 250 mm Ast (Actual) = 804 mm²
BOTTOM REINF.(Top slab)
Ast (mom.) = 391 mm² Ast (shrinkage) = 760 mm² Ast (provided) 760 mm² Bar dia. (ø) = 16 mm Bar spacing c/c = 250 mm Ast (Actual) = 804 mm²
BOTTOM SLAB
Design Moment M = 53.63 KNm Reqd. depth dr(mom) = 207 mm Design Shear V = 152.68 KN Reqd. depth dr(shear) = 356 mm Reqd.Thickness tr = 431 mm Provided thickness ta = 500 mm
Page 100 September 2013 Technical Designs for Tranch‐1 Work
SHRINKAGE REINF (Bottom Slab).
Ast (reqd. exp.face) = 950 mm² Ast (provided) Bar dia. (ø) = 16 mm Bar spacing c/c = 200 mm Ast (Actual) = 1005 mm² Ast (reqd.earth face) = 570 mm² Ast (provided) Bar dia. (ø) = 12 mm Bar spacing c/c = 175 mm Ast (Actual) = 646 mm²
TOP REINF.(Bottom Slab)
Ast (mom.) = 379 mm² Ast (shrinkage) = 760 mm² Ast (provided)= 760 mm² Bar dia. (ø) = 16 mm Bar spacing c/c = 250 mm Ast (Actual) = 804 mm²
BOTTOM REINF (Bottom Slab).
Ast (mom.) = 758 mm² Ast (shrinkage) = 380 mm² Ast (provided) 758 mm² Bar dia. (ø) = 16 mm Bar spacing c/c = 250 mm Ast (Actual) = 804 mm²
ABUTMENTS
Design Moment(Top) M = 44.37 KNm Reqd. depth dr(mom) = 188 mm Design Shear(Top) V = 114.53 KN Reqd. depth dr(shear) = 267 mm Reqd.Thickness tr = 342 mm Provided thickness ta = 450 mm
Design Moment(Bottom) M = 48.78 KNm Reqd. depth dr(mom) = 197 mm Design Shear(Bottom) V = 129.13 KN Reqd. depth dr(shear) = 301 mm Reqd.Thickness tr = 376 mm Provided thickness ta = 500 mm
Page 101 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
SHRINKAGE REINF (Abutment).
Ast (exp.face) = 950 mm² Ast (provided) Bar dia. (ø) = 16 mm Bar spacing c/c = 200 mm Ast (Actual) = 1005 mm²
Ast (earth face) = 570 mm² Ast (provided) Bar dia. (ø) = 12 mm Bar spacing c/c = 175 mm Ast (Actual) = 646 mm²
EXPOSED FACE REINF.(Abutment)
Design moment M = 22.72 KNm Top thickness ta(top) = 450 mm Bottom thickness ta(bot) = 500 mm Length of member l = 2.28 m Depth at zero shear d(zs)= 1.14 m Actual thickness ta(zs) = 475 mm
Ast (mom) = 341 mm² Ast (shrinkage) = 760 mm² Ast (provided) 760 mm² Bar dia. (ø) = 16 mm Bar spacing c/c = 250 mm Ast (Actual) = 804 mm²
EARTH FACE REINF (Abutment, contd).
Moment at top M(top) = 44.37 KNm Reinf.top Ast(top,mom) = 711 mm² Moment at bottom M(bot) = 48.78 KNm Reinf.botm. Ast(bot,mom) = 689 mm² Shrinkage reinf. Ast(sk) = 380 mm² Ast (provided) 711 mm² Bar dia. (ø) = 16 mm Bar spacing c/c = 275 mm Ast (Actual) = 731 mm²
PIERS
Design Moment M = 11.12 KNm Reqd. depth dr(mom) = 94 mm Design Shear V = 22.77 KN Reqd. depth dr(shear) = 53 mm Reqd.Thickness tr = 169 mm Provided thickness ta = 600 mm
Page 102 September 2013 Technical Designs for Tranch‐1 Work
REINFORCEMENTS (Pier)
Ast (mom.) = 127 mm² Ast (shrinkage) = 760 mm² Ast (provided) 760 mm² Bar dia. (ø) = 16 mm Bar spacing c/c = 250 mm Ast (Actual) = 804 mm²
Dimension of the Structure: Box bottom width (outside) 8.80 m
Length of Barrel i/c extensions: 23.60 m D/S Floor length i/c glacis 11.80 m U/S Floor length i/c glacis 10.30 m D/S Floor extension (Return wall toe) 1.80 m U/S Floor extension (Return wall toe) 1.60 m Total Floor Length: 49.10 m
Page 103 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
Name of Project: Main River Flood and Bank Erosion Risk Management Program Regulator/Structure: Drainage Sluice at Gala, Kaizuri (Regulator # 3) WINGWALL AND APRON (R/S) Sirajganj Size: 4V-1.5mx1.8m Structure details
Embankment Crest El 15.60 m PWD Elevation of Operating Deck 14.50 m PWD El of Wing top adjacent to Barrel Extension 13.90 m PWD El of Wing top just above Glacis End 12.80 m PWD El of wing wall at end (top)/GL(River side) 10.50 m PWD Barrel Invert Level/Sill Level 7.00 m PWD El of Wing bottom adjacent to Barrel Extension 7.00 m PWD El of wing bottom at glacis end 6.00 m PWD
Barrel Extension R/S" 1.80 m Barrel Extension C/S" 1.80 m
Length of wing wall from Op Deck end to GL 10.50 m Glacis length (1V:3H) 3.00 m Wing wall top surface slope to GL (1V:xH) 1 3 Length of wing wall (Lw)-total 11.80 m Flat /Horizontal floor adjacent to barrel extension 0.3 m
1.0 REQUIRED INPUT DATA
SECTION LENGTH WINGWALL APRON WINGWALL APRON from (S1)Thick(mm) Height Thick Width Height Width (m) (Top) (Bot) (m) (mm) (m) (m) (m) S L Tt Tb H Ta B H' B' 1-1 3.00 300 750 6.90 800 8.51 7.30 9.26 2-2 6.50 300 750 5.73 800 9.43 6.13 10.18 3-3 8.50 300 650 5.07 700 9.96 5.42 10.61 4-4 10.00 300 500 4.57 600 10.35 4.87 10.85 5-5 11.80 300 500 4.50 600 10.83 4.80 11.33
H' = Height of Wingwall from Apron c/l B' = Width of Apron from c/l of Wingwalls
Length of Wingwall = (L² + ((B - B1)/2)²)^0.5 = 11.86 m
3 Unit Weight of Steel (γst) --> 77.0 KN/m³ 490 lb/ft 3 Unit Weight of Concrete (γc) --> 23.6 KN/m³ 150 lb/ft 3 Unit Weight of Soil (γs) --> 18.8 KN/m³ 120 lb/ft
Angle of Internal Friction (ø) --> 20 ° Coeff. of Active Earth Pressure (Ca) = (1-sinø)/(1+sinø) = 0.490
Ultimate Flexural Strength of Steel (fy) --> 4.14E+05 KN/m² 60,044 psi Ultimate Flexural Strength of Concrete(fc') 2.20E+04 KN/m² 3,191 psi
Allowable Flexural Strength of Steel (fs) = 0.45*fy = 1.86E+05 KN/m² Allowable Flexural Strength of Concrete(fc) = 0.4*f'c = 8.80E+03 KN/m²
Page 104 September 2013 Technical Designs for Tranch‐1 Work
5.4 SUMMARY OF DESIGN INFORMATION Drainage Sluice at Gala, Kaizuri (Regulator # 3) WINGWALL AND APRON (R/S) Size: 4V-1.5mx1.8m DEPTH Of SECTION
Wing Wall Apron Member dr (req) tr (req) ta (Prov) dr (req) tr (req) ta (Prov)
1-1 635 710 750 672 747 800 2-2 481 556 750 512 587 800 3-3 399 474 650 425 500 700 4-4 342 417 500 365 440 600 5-5 334 409 500 357 432 600
REINFORCEMENT
SHRINKAGE REINFORCEMENT EXPOSED EARTH MEMBER Ast (req) φ (dia) Spacing Ast (act) Ast (req) φ (dia) Spacing Ast (act) (mm2) (mm) (mm) (mm2)(mm2) (mm) (mm) (mm2) WINGWALL 1-1 950 16 200 1005 570 12 200 565 2-2 950 16 200 1005 570 12 200 565 3-3 950 16 200 1005 570 12 200 565 4-4 950 16 200 1005 570 12 200 565 5-5 950 16 200 1005 570 12 200 565
APRON 1-1 950 16 200 1005 570 12 200 565 2-2 950 16 200 1005 570 12 200 565 3-3 950 16 200 1005 570 12 200 565 4-4 950 16 200 1005 570 12 200 565 5-5 950 16 200 1005 570 12 200 565
Main Reinforcement Top/Exposed Bottom/Earth Ast (req) φ (dia) Spacing Ast (act) Ast (req) φ (dia) Spacing Ast (act) (mm2) (mm) (mm) (mm2)(mm2) (mm) (mm) (mm2) Wingwall 1-1 760 16 250 804 4490 25 100 4909 2-2 760 16 250 804 2576 25 150 3273 3-3 760 16 250 804 2087 25 175 2805 4-4 760 16 250 804 2067 20 150 2094 5-5 760 16 250 804 1978 20 150 2094
Apron 1-1 950 16 200 1005 4694 25 100 4909 2-2 950 16 200 1005 2722 25 150 3273 3-3 950 16 200 1005 2175 25 175 2805 4-4 950 16 200 1005 1907 20 150 2094 5-5 950 16 200 1005 1827 20 150 2094
Page 105 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
MEMBER THICKNESS, BOND AND BAR CURTAILMENT WINGWALL AND APRON (R/S)
Member Thickness Bond Member Reqd. Act. Design Allowable Act Design. tr (mm) ta (mm) OK/Not OK (KN/m2)(KN/m2) OK/not OK WINGWALL 1-1 710 750 OK 673 463 OK 2-2 556 750 OK 673 480 OK 3-3 474 650 OK 673 513 OK 4-4 417 500 OK 841 604 OK 5-5 409 500 OK 841 587 OK
APRON 1-1 747 800 OK - - - 2-2 587 800 OK - - - 3-3 500 700 OK - - - 4-4 440 600 OK - - - 5-5 432 600 OK - - -
Bar Curtailment Height or Width (B/2) 1st curtailment 2nd Curtailment (m) Loc (m) Yes/No Loc (m) Yes/No Wing Wall 1-1 6.90 2.13 Yes 3.38 Yes 2-2 5.73 1.24 Yes 2.43 Yes 3-3 5.07 1.29 Yes 2.27 Yes 4-4 4.57 1.45 Yes 2.22 Yes 5-5 4.50 1.37 Yes 2.15 Yes
APRON 1-1 4.26 4.26 No 4.26 No 2-2 4.72 2.80 Yes 4.72 No 3-3 4.98 2.36 Yes 4.98 No 4-4 5.18 2.41 Yes 5.43 Yes 5-5 5.41 2.31 Yes 5.66 Yes
USER DEFINED REINFORCEMENT
MEMBER SHRINKAGE REINFORCEMENT EXPOSED FACE EARTH FACE Ast(req) φ (bar dia) spacing Ast(act) Ast(req) φ (bar dia) spacing Ast(act) (mm2) (mm) (mm) (mm2)(mm2) (mm) (mm) (mm2) WINGWALL 1-1 950 16 200 1005 570 12 200 565 2-2 950 16 200 1005 570 12 200 565 3-3 950 16 200 1005 570 12 200 565 4-4 950 16 200 1005 570 12 200 565 5-5 950 16 200 1005 570 12 200 565
APRON 1-1 950 16 200 1005 570 12 200 565 2-2 950 16 200 1005 570 12 200 565 3-3 950 16 200 1005 570 12 200 565 4-4 950 16 200 1005 570 12 200 565 5-5 950 16 200 1005 570 12 200 565
Page 106 September 2013 Technical Designs for Tranch‐1 Work
WINGWALL AND APRON (R/S) Size: 4V-1.5mx1.8m
MAIN REINFORCEMENT TOP/ EXPOSED BOTTOM/ EARTH Ast(req) φ (bar dia) spacing Ast(act) Ast(req) φ (bar dia) spacing Ast(act) (mm2) (mm) (mm) (mm2)(mm2) (mm) (mm) (mm2) WINGWALL 1-1 760 16 250 804 4490 25 100 4909 2-2 760 16 250 804 2576 25 150 3273 3-3 760 16 250 804 2087 25 175 2805 4-4 760 16 250 804 2067 20 150 2094 5-5 760 16 250 804 1978 20 150 2094
APRON 1-1 950 16 200 1005 4694 25 100 4909 2-2 950 16 200 1005 2722 25 150 3273 3-3 950 16 200 1005 2175 25 175 2805 4-4 950 16 200 1005 1907 20 150 2094 5-5 950 16 200 1005 1827 20 150 2094
Sec # Sec Dist Sec sec (m) Width (m) height (m) Sec 0-0, W0 0.00 7.80 6.90 Sec 1-1, W1 3.00 8.51 6.90 Sec2-2,W2 6.50 9.43 5.73 Sec3-3,W3 8.50 9.96 5.07 Sec4-4,W4 10.00 10.35 4.57 Sec 5-5,W5 11.80 10.83 4.50
Page 107 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
Name of Project: Main River Flood and Bank Erosion Risk Management Program Regulator/Structure: Drainage Sluice at Gala, Kaizuri (Regulator # 3) Size: 4V-1.5mx1.8m WINGWALL AND APRON (C/S) Sirajganj
Structure details Creset level of Embankment 15.60 m PWD Operation Deck Elevation 14.50 m PWD El of Wing Top adjacent to Barrel Extension 13.38 m PWD El of Wing Top just above Glacis End 12.66 m PWD El of wing wall at end (top)/GL (Country side) 10.50 m PWD Barrel Invert Level/Sill Level 7.00 m PWD El of Wing bottom adjacent to Barrel Extension 7.00 m PWD El of wing bottom at glacis end 6.50 m PWD
Barrel Extension R/S" 1.80 m Barrel Extension C/S" 1.80 m
Length of wing wall from OP deck end to Glacis end 7.50 m Glacis length (1V:3H) 1.50 m Embankment slope (C/S), 1V:xH 1 2.5
Length of wing wall (Lw) 10.30 m Flat /Horizontal floor adjacent to barrel extension 0.30 m
1.0 REQUIRED INPUT DATA
SECTION LENGTH WINGWALL APRON WINGWALL APRON from (S1)Thick(mm) Height Thick Width Height Width (m) (Top) (Bot) (m) (mm) (m) (m) (m) S L Tt Tb H Ta B H' B' 1-1 1.50 300 650 6.38 700 8.12 6.73 8.77 2-2 3.50 300 650 5.48 700 8.64 5.83 9.29 3-3 6.50 300 550 4.28 600 9.43 4.58 9.98 4-4 9.30 300 500 4.00 550 10.17 4.28 10.67 5-5 10.30 300 450 4.00 500 10.43 4.25 10.88
H' = Height of Wingwall from Apron c/l B' = Width of Apron from c/l of Wingwalls
Length of Wingwall = (L² + ((B - B1)/2)²)^0.5 = 10.36 m
3 Unit Weight of Steel (γst) --> 77.0 KN/m³ 490 lb/ft 3 Unit Weight of Concrete (γc) --> 23.6 KN/m³ 150 lb/ft 3 Unit Weight of Soil (γs) --> 18.8 KN/m³ 120 lb/ft Angle of Internal Friction (ø) --> 20 ° Coeff. of Active Earth Pressure (Ca) = (1-sinø)/(1+sinø) = 0.490
Ultimate Flexural Strength of Steel (fy) --> 4.14E+05 KN/m² 60,044 psi Ultimate Flexural Strength of Concrete(fc') 2.20E+04 KN/m² 3,191 psi
Allowable Flexural Strength of Steel (fs) = 0.45*fy = 1.86E+05 KN/m² Allowable Flexural Strength of Concrete(fc) = 0.4*f'c = 8.80E+03 KN/m²
Allowable Shear Stress of Concrete(v) =2.89*f'c^0.5 = 4.29E+02 KN/m²
Page 108 September 2013 Technical Designs for Tranch‐1 Work
Drainage Sluice at Gala, Kaizuri (Regulator # 3) 5.4 SUMMARY OF DESIGN INFORMATION WINGWALL AND APRON (C/S) Size: 4V-1.5mx1.8m DEPTH Of SECTION
Wing Wall Apron Member dr (req) tr (req) ta (Prov) dr (req) tr (req) ta (Prov)
1-1 564 639 650 597 672 700 2-2 449 524 650 477 552 700 3-3 310 385 550 330 405 600 4-4 280 355 500 298 373 550 5-5 280 355 450 297 372 500
REINFORCEMENT
MEMBER SHRINKAGE REINFORCEMENT EXPOSED EARTH Ast (req) φ (dia) Spacing Ast (act) Ast (req) φ (dia) Spacing Ast (act) (mm2) (mm) (mm) (mm2)(mm2) (mm) (mm) (mm2) WINGWALL 1-1 950 16 200 1005 570 12 200 565 2-2 950 16 200 1005 570 12 200 565 3-3 950 16 200 1005 570 12 200 565 4-4 950 16 200 1005 570 12 200 565 5-5 950 16 200 1005 570 12 200 565
APRON 1-1 950 16 200 1005 570 12 200 565 2-2 950 16 200 1005 570 12 200 565 3-3 950 16 200 1005 570 12 200 565 4-4 950 16 200 1005 570 12 200 565 5-5 950 16 200 1005 570 12 200 565
Main Reinforcement Top/Exposed Bottom/Earth Ast (req) φ (dia) Spacing Ast (act) Ast (req) φ (dia) Spacing Ast (act) (mm2) (mm) (mm) (mm2)(mm2) (mm) (mm) (mm2) Wingwall 1-1 760 16 250 804 4167 25 100 4909 2-2 760 16 250 804 2640 20 100 3142 3-3 760 16 250 804 1523 20 150 2094 4-4 760 16 250 804 1389 20 150 2094 5-5 760 16 250 804 1575 20 150 2094
Apron 1-1 950 16 200 1005 4285 25 100 4909 2-2 950 16 200 1005 2741 20 100 3142 3-3 950 16 200 1005 1559 20 150 2094 4-4 950 16 200 1005 1403 20 150 2094 5-5 950 16 200 1005 1558 20 150 2094
Page 109 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
WINGWALL AND APRON (C/S) MEMBER THICKNESS, BOND AND BAR CURTAILMENT Size: 4V-1.5mx1.8m
Member Thickness Bond Member Reqd. Act. Design Allowable Act Design. tr (mm) ta (mm) OK/Not OK (KN/m2)(KN/m2) OK/not OK WINGWALL 1-1 639 650 OK 673 465 OK 2-2 524 650 OK 841 429 OK 3-3 385 550 OK 841 475 OK 4-4 355 500 OK 841 463 OK 5-5 355 450 OK 841 525 OK
APRON 1-1 672 700 OK - - - 2-2 552 700 OK - - - 3-3 405 600 OK - - - 4-4 373 550 OK - - - 5-5 372 500 OK - - -
Bar Curtailment Height or Width (B/2) 1st curtailment 2nd Curtailment (m) Loc (m) Yes/No Loc (m) Yes/No Wing Wall 1-1 6.38 1.76 Yes 2.95 Yes 2-2 5.48 1.24 Yes 2.33 Yes 3-3 4.28 1.04 Yes 1.87 Yes 4-4 4.00 0.83 Yes 2.00 Yes 5-5 4.00 0.94 Yes 1.69 Yes
APRON 1-1 4.06 4.06 No 4.06 No 2-2 4.32 3.00 Yes 4.32 No 3-3 4.72 1.92 Yes 4.72 No 4-4 5.08 1.78 Yes 5.33 Yes 5-5 5.22 1.90 Yes 5.44 Yes
USER DEFINED REINFORCEMENT
MEMBER SHRINKAGE REINFORCEMENT EXPOSED EARTH Ast(req) φ (bar dia) spacing Ast(act) Ast(req) φ (bar dia) spacing Ast(act) (mm2) (mm) (mm) (mm2)(mm2) (mm) (mm) (mm2) WINGWALL 1-1 950 16 200 1005 570 12 200 565 2-2 950 16 200 1005 570 12 200 565 3-3 950 16 200 1005 570 12 200 565 4-4 950 16 200 1005 570 12 200 565 5-5 950 16 200 1005 570 12 200 565
APRON 1-1 950 16 200 1005 570 12 200 565 2-2 950 16 200 1005 570 12 200 565 3-3 950 16 200 1005 570 12 200 565 4-4 950 16 200 1005 570 12 200 565 5-5 950 16 200 1005 570 12 200 565
Page 110 September 2013 Technical Designs for Tranch‐1 Work
WINGWALL AND APRON (C/S)
MAIN REINFORCEMENT member TOP/ EXPOSED BOTTOM/ EARTH Ast(req) φ (bar dia) spacing Ast(act) Ast(req) φ (bar dia) spacing Ast(act) (mm2) (mm) (mm) (mm2)(mm2) (mm) (mm) (mm2) WINGWALL 1-1 760 16 250 804 4167 25 100 4909 2-2 760 16 250 804 2640 20 100 3142 3-3 760 16 250 804 1523 20 150 2094 4-4 760 16 250 804 1389 20 150 2094 5-5 760 16 250 804 1575 20 150 2094
APRON 1-1 950 16 200 1005 4285 25 100 4909 2-2 950 16 200 1005 2741 20 100 3142 3-3 950 16 200 1005 1559 20 150 2094 4-4 950 16 200 1005 1403 20 150 2094 5-5 950 16 200 1005 1558 20 150 2094
Section Sec dist width (m) Height (m) (m) Sec 0-0, W0 0.00 7.80 6.38 Sec 1-1, W1 1.50 8.12 6.28 Sec2-2,W2 3.50 8.64 5.48 Sec3-3,W3 6.50 9.43 4.28 Sec4-4,W4 9.30 10.17 4.00 Sec 5-5,W5 10.30 10.43 4.00
Page 111 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
Name of Project: Main River Flood and Bank Erosion Risk Management Program Regulator/Structure: Drainage Sluice at Gala, Kaizuri (Regulator # 3) RETURN WALL (D/S) Sirajganj Size: 4V-1.5mx1.8m 1.0 REQUIRED INPUT DATA
3 Unit Weight of Steel (γst) --> 77.00 KN/m 3 Unit Weight of Concrete (γc) --> 23.60 KN/m 3 Unit Weight of Soil (γs) --> 18.90 KN/m
Unit Weight of Water (γw) --> 9.81 m/sec/sec
Angle of Internal Friction (ø) --> 20 ° Coeff. of Active Earth Pressure (Ca) = (1-sinø)/(1+sinø) = 0.49 Coeff. of Friction (f) --> 0.50
Return Wall Top Level --> 10.50 m PWD Bottom Slab Level --> 6.00 m PWD
Return Wall Top Thick --> 300 mm Return Wall Bottom Thick -> 500 mm Bottom Slab Thickness --> 600 mm
Height of Return Wall (H) = 4.50 m Height of Return Wall i/c base (H') = 5.10 m
Length of Return Wall --> 9.50 m Length of Heel --> 2.00 m P1 = 70.36 Length of Toe --> 1.80 m P2 = 60.79 Total Length (width) of B.Slab = 4.30 m 84.31%
Ultimate Flexural Strength of Steel (fy) = 4.14E+05 KN/m² 60,044 psi Ultimate Flexural Strength of Concrete(f'c) = 2.20E+04 KN/m² 3,191 psi
Allowable Flexural Strength of Steel (fs) = 0.45*fy = 1.86E+05 KN/m² Allowable Flexural Strength of Concrete(fc) = 0.4*f'c = 8.80E+03 KN/m²
Allowable Shear Stress of Concrete(v) = 2.89* f'c1/2 = 4.29E+02 KN/m²
Allowable Bond Stress (bs(allow)) = 113.40*f'c1/2/d = 1.68E+04 /d KN/m2
(d = Bar Diameter, mm) OR --> 1103 KN/m² (whichever is less)
Modulus of Elasticity of Steel (Es) --> 1.96E+08 KN/m² Modulus of Elasticity of Concrete (Ec) --> 1.98E+07 KN/m²
Coverage + 1/2 Dia.Reinforcement (c) --> 75 mm
b = Unit Width of Member = 1.00 m n = Modular Ratio = Es / Ec = 9.90 r = fs /fc = 21.17 k = n/(n + r) = 0.319 j = Lever Arm Coefficient = 1 - k/3 = 0.894 R = Resisting Moment Coefficient = fc*j*k/2 = 1.25E+03 KN/m²
Page 112 September 2013 Technical Designs for Tranch‐1 Work
Drainage Sluice at Gala, Kaizuri (Regulator # 3) USER DEFINED REINFORCEMENT RETURN WALL (D/S) Size: 4V-1.5mx1.8m
MEMBER SHRINKAGE REINFORCEMENT EXPOSED EARTH Ast (req) φ (dia) spacing Ast (act) Ast (req) φ (dia) spacing Ast (act) (mm2) (mm) (mm) (mm2) (mm2) (mm) (mm) (mm2)
STEM 950 16 200 1005 570 12 200 565
HEEL 950 16 200 1005 570 12 200 565
TOE 950 16 200 1005 570 12 200 565
MAIN REINFORCEMENT TOP/EXPOSED BOTTOM/EARTH Ast (req) φ (dia) spacing Ast (act) Ast (req) φ (dia) spacing Ast (act) (mm2) (mm) (mm) (mm2) (mm2) (mm) (mm) (mm2)
STEM 570 12 200 565 1989 20 125 2513
HEEL 1425 16 125 1608 - - --
TOE -- - - 1279 16 125 1608
STABILITY
LOADS AND MOMENTS Total weight = 281.97 KN Resisting moment = 796.37 KNm Over turning moment = 204.87 KNm
F.S (over turning) = 3.89 Should be > 1.5 F.S (sliding) = 1.17 Should be > 1.5
FOUNDATION PRESSURE Resultant action point from toe = 2.10 m Ecentricity e = 0.05 m
Pressure at toe, P1 = 70.36 KN/m² Pressure at heel, P2 = 60.79 KN/m²
MEMBER THICKNESS Member thickness Member Moment Shear Required Provided dr(mom) dr(shear) tr(req) ta(act) (KNm) (KN) (mm) (mm) (mm) (mm) STEM 140.73 93.82 335 219 410 500 HEEL 124.55 126.03 315 294 390 600 TOE 111.82 123.04 299 287 374 600
Note: Heel: top tension and shear downward Toe : bottom tension and shear upward
Page 113 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
REINFORCEMENTS RETURN WALL (D/S)
Member Ast requird moment shrink Bar dia Spacing Ast ø @ provided (mm²) (mm²) (mm) (mm c/c) (mm²) STEM Ver exp face 570 12 200 565 Ver earth face 1989 - 20 125 2513 Hor exp face 950 16 200 1005 Hor earth face 570 12 200 565
HEEL Hor main(top) 1425 - 16 125 1608 Hor.top(long) 950 12 200 565 Hor botm(short) 380 12 300 377 Hor botm(long) 570 12 200 565
TOE Hor main(botm) 1279 - 16 125 1608 Hor.top(long) 950 16 200 1005 Hor top(short) 380 12 300 377 Hor botm(long) 570 12 200 565
BAR CURTAILMENTS
Member Curt. ht. Depth of Curt. pt. from top sectn.at 24ø above bot Ast Ast h curt.pt. slab, x momt. shrink (m) da (mm) (mm) (m) (mm²) (mm²) STEM 1st curtailment 3.76 392 480 1.22 1257 380 2nd curtailment 2.88 353 480 2.10 628 380
BOND Bar Bond Max(allow Design Total bar Bond Member dia. allowab able)bond shear perimeter develop ø bs(allow) stress V tp bs(ac.) (mm) (KN/m²) (KN/m²) (KN) (mm) (KN/m²)
STEM 20 841 1103 93.82 503 491 HEEL 16 1051 1103 -126.03 402 -668 TOE 16 1051 1103 123.04 402 249
Note: 0.00
Page 114 September 2013 Technical Designs for Tranch‐1 Work
Name of Project: Main River Flood and Bank Erosion Risk Management Program Regulator/Structure: Drainage Sluice at Gala, Kaizuri (Regulator # 3) RETURN WALL (C/S) Size: 4V-1.5mx1.8m Sirajganj 1.0 REQUIRED INPUT DATA
3 Unit Weight of Steel (γst) --> 77.00 KN/m 3 Unit Weight of Concrete (γc) --> 23.60 KN/m 3 Unit Weight of Soil (γs) --> 18.90 KN/m
Unit Weight of Water (γw) --> 9.81 m/sec/sec
Angle of Internal Friction (ø) --> 20 ° Coeff. of Active Earth Pressure (Ca) = (1-sinø)/(1+sinø) = 0.49 Coeff. of Friction (f) --> 0.50
Return Wall Top Level --> 10.50 m PWD Bottom Slab Level --> 6.50 m PWD
Return Wall Top Thick --> 300 mm Return Wall Bottom Thick -> 450 mm Bottom Slab Thickness --> 500 mm
Height of Return Wall (H) = 4.00 m Height of Return Wall i/c base (H') = 4.50 m
Length of Return Wall --> 8.50 m Length of Heel --> 1.80 m P1 = 60.08 psf Length of Toe --> 1.60 m P2 = 55.54 psf Total Length (width) of B.Slab = 3.85 m 85.56%
Ultimate Flexural Strength of Steel (fy) = 4.14E+05 KN/m² 60,044 psi Ultimate Flexural Strength of Concrete(f'c) = 2.20E+04 KN/m² 3,191 psi
Allowable Flexural Strength of Steel (fs) = 0.45*fy = 1.86E+05 KN/m² Allowable Flexural Strength of Concrete(fc) = 0.4*f'c = 8.80E+03 KN/m²
Allowable Shear Stress of Concrete(v) = 2.89* f'c1/2 = 4.29E+02 KN/m²
Allowable Bond Stress (bs(allow)) = 113.40*f'c1/2/d = 1.68E+04 /d KN/m2
(d = Bar Diameter, mm) OR --> 1103 KN/m² (whichever is less)
Modulus of Elasticity of Steel (Es) --> 1.96E+08 KN/m² Modulus of Elasticity of Concrete (Ec) --> 1.98E+07 KN/m²
Coverage + 1/2 Dia.Reinforcement (c) --> 75 mm
b = Unit Width of Member = 1.00 m n = Modular Ratio = Es / Ec = 9.90 r = fs /fc = 21.17 k = n/(n + r) = 0.319 j = Lever Arm Coefficient = 1 - k/3 = 0.894 R = Resisting Moment Coefficient = fc*j*k/2 = 1.25E+03 KN/m²
Page 115 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
Drainage Sluice at Gala, Kaizuri (Regulator # 3) USER DEFINED REINFORCEMENT RETURN WALL (C/S) Size: 4V-1.5mx1.8m
MEMBER SHRINKAGE REINFORCEMENT EXPOSED EARTH Ast (req) φ (dia) spacing Ast (act) Ast (req) φ (dia) spacing Ast (act) (mm2) (mm) (mm) (mm2) (mm2) (mm) (mm) (mm2)
STEM 570 12 200 565 380 12 300 377
HEEL 570 12 200 565 380 12 300 377
TOE 570 12 200 565 380 12 300 377
MAIN REINFORCEMENT TOP/EXPOSED BOTTOM/EARTH Ast (req) φ (dia) spacing Ast (act) Ast (req) φ (dia) spacing Ast (act) (mm2) (mm) (mm) (mm2) (mm2) (mm) (mm) (mm2)
STEM 570 12 200 565 1583 20 150 2094
HEEL 1288 16 150 1340 - - - -
TOE - - - - 1075 16 150 1340
STABILITY
LOADS AND MOMENTS Total weight = 222.58 KN Resisting moment = 563.59 KNm Over turning moment = 140.73 KNm
F.S (over turning) = 4.00 Should be > 1.5 F.S (sliding) = 1.19 Should be > 1.5
FOUNDATION PRESSURE Resultant action point from toe = 1.90 m Ecentricity e = 0.03 m
Pressure at toe, P1 = 60.08 KN/m² Pressure at heel, P2 = 55.54 KN/m²
MEMBER THICKNESS Member thickness Member Moment Shear Required Provided dr(mom) dr(shear) tr(req) ta(act) (KNm) (KN) (mm) (mm) (mm) (mm) STEM 98.84 74.13 281 173 356 450 HEEL 91.13 101.89 270 238 345 500 TOE 76.10 94.62 246 221 321 500
Note: Heel: top tension and shear downward Toe : bottom tension and shear upward
Page 116 September 2013 Technical Designs for Tranch‐1 Work
REINFORCEMENTS RETURN WALL (C/S) Size: 4V-1.5mx1.8m
Member Ast requird moment shrink Bar dia Spacing Ast ø @ provided (mm²) (mm²) (mm) (mm c/c) (mm²) STEM Ver exp face 570 12 200 565 Ver earth face 1583 - 20 150 2094 Hor exp face 570 12 200 565 Hor earth face 380 12 300 377
HEEL Hor main(top) 1288 - 16 150 1340 Hor.top(long) 570 12 300 377 Hor botm(short) 380 12 300 377 Hor botm(long) 380 12 300 377
TOE Hor main(botm) 1075 - 16 150 1340 Hor.top(long) 570 12 200 565 Hor top(short) 380 12 300 377 Hor botm(long) 380 12 300 377
BAR CURTAILMENTS
Member Curt. ht. Depth of Curt. pt. from top sectn.at 24ø above bot Ast Ast h curt.pt. slab, x momt. shrink (m) da (mm) (mm) (m) (mm²) (mm²) STEM 1st curtailment 3.41 353 480 1.07 1047 380 2nd curtailment 2.63 324 480 1.85 524 380
BOND Bar Bond Max(allow Design Total bar Bond Member dia. allowab able)bond shear perimeter develop ø bs(allow) stress V tp bs(ac.) (mm) (KN/m²) (KN/m²) (KN) (mm) (KN/m²)
STEM 20 841 1103 74.13 419 528 HEEL 16 1051 1103 -101.89 335 -800 TOE 16 1051 1103 94.62 335 237
Note: 0.00
Page 117 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
Name of Project: Main River Flood and Bank Erosion Risk Management Program Location: Kaizuri Name of Structure: Drainage Sluice at Gala, Kaizuri (Regulator # 3) Size: 4V-1.5mx1.8m
EXIT GRADIENT AND UPLIFT PRESSURE (Non Tidal Zone)
REQUIRED INPUT DATA
Maximum Water Level C/S & R/S Highest High Water Level (observed) 13.70 m PWD Maximum Water Level C/S 11.50 m PWD (Average ground level+ 1.0 m)
Drainage Mode (R/S Floor Thickness) Design C/S Water Level --> 8.50 m PWD Design R/S Water Level 7.50 m PWD
Flushing Mode (C/S Floor Thickness) Design C/S Water Level --> 8.00 m PWD Monsoon WL Design R/S Water Level --> 9.00 m PWD 1 in 20 year WL I L 4.45 U/S Apron Level --> 6.50 m PWD C/S Dr. 0.60 D/S Apron Level --> 6.00 m PWD R/S Dr. 0.60
Elevation at bottom of U/S Cutoff Wall --> 3.50 m Elevation at bottom of D/S Cutoff Wall --> 2.00 m
3.00 Cut off depth,c/s 4.00 Cut off depth,r/s
Elevation underneath apron at U/S Cutoff Wall-> 6.00 m PWD Elevation underneath apron at D/S Cutoff Wall -> 5.40 m PWD
Appron End Thickness Provided (U/S) 0.50 0.14 Required Provided (D/S) 0.60 0.17 Required
Total Floor Length (b) --> 49.10 m Distance between U/S and D/S Cutoff Walls (b')-> 48.20 m
Intermediate Points where Floor Thickness is Desired: Section Length (m) from Section 1 (U/S) ------1 (U/S) 0.00 2 10.05 3 11.85 SCHEMATIC VIEW OF STRUCTURE 4 35.35 5 38.65 Drainage Mode Water Levels ------6 (D/S) 48.20 Flushing Mode Water Levels - - - - -
1.00 9.90 1.40 1.40 12.40 1.00
8.50 m 8.50 9.00 m 0.70 -*------*------7.80 Barrel 7.80 =Bank 0.70 U/S D/S 8.00 m 7.50 m 1.30 -*------*------1.80 4.45 B3 = 4.00 6.50 m 0.00 6.00 m Apron 4.00 =B3 0.50 0.50 0.60 0.00 0.00 6.00 m 5.40 2 3 4 5 6 <-- Cutoff 3.00 1.00 9.50 1.80 23.50 3.30 10.50 1.00 Wall 4.00 3.50 m 2.00 48.20 m 49.10 m
EXIT GRADIENT
Page 118 September 2013 Technical Designs for Tranch‐1 Work
Exit gradient is calculated using Khosla's equation.
Drainage Mode
Ge = Exit Gradient = H/d*(1/pi*r^0.5)
H = Design Head = U/S Water Level - D/S Water Level = 1.00 m
d = Length (depth) of D/S Cutoff Wall = D/S Channel Level - Elevation at bottom of D/S Cutoff Wall 4.00 m
b = Total Floor Length = 49.10 m
a = b/d = 12.28
r = (1 + (1 + a^2)^0.5)/2 = 6.66
Ge = 0.031 <›_ Maximum Permitted Gradient (1/7)
Floor and D/S Cutoff Wall Length is O.K.
Flushing Mode
Ge = Exit Gradient = H/d*(1/pi*r^0.5)
H = Design Head = 1.00 m
d = Length (depth) of U/S Cutoff Wall = 3.00 m
a = b/d = 16.37
r = (1 + (1 + a^2)^0.5)/2 = 8.70
Ge = 0.036 <›_ Maximum Permitted Gradient (1/6 to 1/7) 0.143
Floor and D/S Cutoff Wall Length is O.K.
UPLIFT PRESSURE
The method used to determine the percentage uplift at various key points underneath the structure was developed by Khosla. The key points at the U/S and D/S cut-off walls are defined in the figure below.
U/S D/S
E1 C1 E6 C6
D1 D6
Drainage Mode
Upstream Cutoff Wall
b = Total Floor Length = 49.10 m d = Length (depth) of U/S Cutoff Wall = 3.00 m
a = b/d = 16.37 r = (1 + (1 + a^2)^0.5)/2 = 8.70
øE1 = 100%
øC1 = 100% - acos((r-2)/r)/pi = 77.98%
øD1 = 100% - acos((r-1)/r)/pi = 84.59%
øC1 must be corrected for the following conditions: c1 = correction due to effect of D/S Cutoff Wall c2 = correction due to thickness of floor
c1 = 19 * (d"/b')^0.5 * (d'+d")/b
b = Total Floor Length = 49.10 m
Page 119 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
b' = Distance between U/S and D/S Cutoff Walls = 48.20 m
d' = Elevation underneath apron at U/S Cutoff Wall minus Elevation at bottom of U/s Cutoff Wall 2.50 m
d" = Elevation underneath apron at D/S Cutoff Wall minus Elevation at bottom of D/S Cutoff Wall 3.40 m
c1 = 60.64% (+ve)
c2 = [(øD1 - øC1)*Tc1]/d1
Tc1 = Thickness of Concrete at Section 1 (U/S) = U/S Apron Level - Elev. underneath apron at U/S Cutoff Wall = 0.50 m
d1 = Depth of U/s Cutoff Wall = U/S Apron Level - Elevation at bottom of U/S Cutoff Wall = 3.00 m
c2 = 1.10% (+ve)
øC1 (corrected) = øC1 + c1 + c2 = 139.72%
Downstream Cutoff Wall
a = b/d = 12.28
r = (1 + (1 + a^2)^0.5)/2 = 6.66
øC6 = 0%
øE6 = acos((r-2)/r)/pi = 25.34%
øD6 = acos((r-1)/r)/pi = 17.67%
øE6 must be corrected for the effect of the U/S Cutoff Wall (c1) and thickness of floor (C2)
c1 = 19 * (d"/b')^0.5 * (d'+d")/b = 19.00 0.20 0.108 = 0.41% (-ve)
c2 = [(øE6 - øD6)* Tc6]/d6 1.15%
øE6 (corrected) = øE6 + c1 + c2 = 23.78%
Required Concrete Thickness
Design Head (H) = U/S Water Level - D/S Water Level = 1.00 m
u = submerged unit weight of concrete= unit weight of concrete / unit weight of water = 1.41
Concrete Thickness (m) = H* φ /u
Section Length from φ% Concrete Uplift Pressure Used (t) upstream end (m) Thickness (m) (Kn/m2) R/S (m) 1 U/S 0.00 139.72% 0.99 13.71 2 10.05 115.54% 0.82 11.33 3 11.85 111.21% 0.79 10.91 4 35.35 54.69% 0.39 5.36 0.80 5 38.65 46.75% 0.33 4.59 0.70 6 D/S 48.20 23.78% 0.17 2.33 0.60
Flushing Mode
Upstream Cutoff Wall
a = b/d = 16.37
r = (1 + (1 + a^2)^0.5)/2 = 8.70
øC1 = 0%
øE1 = acos((r-2)/r)/pi = 22.02%
øD1 = acos((r-1)/r)/pi = 15.41% øE1 must be corrected for the effect of the D/S Cutoff Wall (c1) and the thickness of floor (c2)
Page 120 September 2013 Technical Designs for Tranch‐1 Work
c1 = 19 * (d"/b')^0.5 * (d'+d")/b = 19.00 0.29 0.13 = 0.72%
c2 = [(øE1 - øD1)*Tc1]/d1 = 1.10% (-ve)
øE1 (corrected) = øE1 + c1 + c2 = 20.20%
Downstream Cutoff Wall
a = b/d = 12.28
r = (1 + (1 + a^2)^0.5)/2 = 6.66
øE6 = 100%
øC6 = 100% - acos((r-2)/r)/pi = 74.66%
øD6 = 100% - acos((r-1)/r)/pi = 82.33%
øC6 must be corrected for the effect of the U/S Cutoff Wall (c1) and thickness of the wall (c2)
c1 = 19 * (d"/b')^0.5*(d'+d")/b = 19.00 0.20 0.11 = 0.41%
c2 = ((øD6 - øC6)*Tc6)/d6 = 1.15%
øC6 (corrected) = øC6 + c1 + c2 = 76.22%
Required Concrete Thickness
Design Head (H) = U/S Water Level - D/S Water Level = 1.00 m
u = submerged unit weight of concrete= unit weight of concrete/ unit weight of water = 1.41
Concrete Thickness (m) = H*φ / u
Length from ø % Concrete Used section U/S end (m) thick (m) 1 U/S 0.00 20.20% 0.14 0.50 2 10.05 31.88% 0.23 0.60 3 11.85 33.97% 0.24 0.70 4 35.35 61.28% 0.44 5 38.65 65.12% 0.47 6D/S 48.20 76.22% 0.54
Checking of Total Floor Length Against Under Seepage:
C= 6.00 H = 1.00 C X H = 6.00 m, Required Creep Length Creep Length Provided = 27.87 m > 6.00 m OK
Considering HHWL (observed) River Side and Maximum Water Level inside project
C= 6.00 H = 2.20 C X H = 13.20 m, Required Creep Length Creep Length Provided = 27.87 m > 13.20 m OK
Page 121 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
Appendix III: The Preliminary Estimates for Tranch‐1, Tranch‐2 and Tranch‐3 Estimate for Tranch‐1
Estimate for proposed intervention (Tranch1) 05.08.2013 I. River: Brahmaputra‐Jamuna
A. Embankment (Composite section with provision of selected Settlement, wide mid part)
A1. Right Bank of Jamuna River (D/S of Jamuna Bridge) Length Ht of Embk Cost/m Est amnt (km) (m) BDT (i). Enayetpur‐Kaijuri (NS) 10.5 5.0 28,620 300,510,193 (Tranch‐1) (S) 2.0 5.0 33,962 67,924,037 Sub‐total 12.5 km BDT 368,434,230 US$ 4,605,428
(iii). Hurasagar‐shahzadpur (NS) 6.0 4.5 24,647 147,882,003 (Tranch‐1) (NS) 1.5 4.0 20,674 31,010,974 (NS) 3.0 3.0 13,712 41,136,137 Sub‐total 10.5 km BDT 220,029,113 US$ 2,750,364
Sub‐total‐(RB Embankment) 23.0 BDT 588,463,343 US$ 7,355,792
Note: (i) The embankment section [marked 'S'] includes a 10 m wide Road Section (5.5m carriage way+ 2x1.5m paved shoulder+2x0.75m verge) in C/S, 8.0 wide re‐settlement area in R/S , 3.2 m wide Crest (mid portion) and 1V:2.5H slope in both side (to GL) for section with Selllement. (ii) The othern sectio [marked 'NS'] includes a 10.0 m wide road section (5.5m carriage way+ 2x1.5m paved shoulder+2x0.75m verge) in C/S, 3.2m wide crest in R/S, no re‐settlement area and 1V:3H slope in R/S and 1V:2.5H in C/S.
B. Road (Enayetpur‐Kaizuri) 1. Rural Road (5.5m carriage way+2x1.5m Shoulder) 5.00 km 25,000,000 km 125,000,000 US$ 2. RCC road for VNM (2.8m, 100 mm thick) 5.00 km 4,500,000 km 22,500,000 US$ 3. Grass stone along the slope of crest of embankment (13 km) 5.0 6261 m2/km 39,131 nos/km each 270.00 52,827,106 US$
Total (Road) 200,327,106 US$ 2,504,089
C. Structures C1: Structures along the Right Bank (Jamuna) (i) RCC Regulators (1 vent) BDT BDT 1 no 19,700,000 19,700,000 (ii) RCC Regulator (2 vent) 1 no 26,300,000 26,300,000 (ii) RCC Regulators (4 vent) 1 nos 37,700,000 37,700,000 (iii) RCC Regulator (6 vent) 1 no 50,900,000 50,900,000
Cost of new structures: BDT 134,600,000 US$ 1,682,500
C2. Repair of Structures (i) RCC Regulators 3 nos LS 2,000,000 6,000,000 US$ 75,000
Total Cost of Structures (new & repair) BDT 140,600,000 US$ 1,757,500
Page 122 September 2013 Technical Designs for Tranch‐1 Work
D. Proposed Protection length (Jamuna River)
D1. Left Bank (i) Chouhali to Nagarpur 5.00 km 255,500,000 1,277,500,000 (ii) Zaffarganj‐ Bachamara 2.00 km 255,500,000 511,000,000
Sub‐total (LB pr work): 7.00 km BDT 1,788,500,000 US$ 22,356,250
C2. Right Bank (i) About 1.0 km around Benotia 1.00 km 255,500,000 255,500,000 US$ 3,193,750
Total Protection Work (both bank) BDT 2,044,000,000 US$ 25,550,000
D. Land Acquisition (D1) Embankment Length land/km T.land (km) (Ha) (Ha) (I). Right Bank (i). Enayetpur‐Kaijuri (NS) 10.5 4.50 47.25 (S) 2.0 5.00 10.00 57.25 ha
(ii) Hurasagar ‐Shahjadpr (NS) 6.0 4.23 25.35 ha
(Repair) (S) 1.5 1.19 1.78 (30% of required land to be acquired) (Repair) (NS) 3.0 1.02 3.06 (30% of required land to be acquired) 4.84 ha Land for RB Embankment 23.0 87.44 ha
Cost of land acquisition for RB embankment (Jamuna) 87.44 ha 7,400,000 BDT 647,037,500 US$ 8,087,969
(D2) Bank Protection (i) Left Bank (a) Chouhali‐Nagarpur 5.00 km 15.00 ha (b) Zaffarganj‐Bachamara 2.00 km 6.00 ha sub‐Total (LB) 7.00 km 21.00 ha
(ii) Right Bank (a). 1.0 km around Benotia 1.00 km 3.00 ha Total Land for LB & RB Protection 8.0 km 24.00 ha Land Acquisition (For Bsnk Protection): 24.0 ha 6,910,000.00 BDT 165,840,000 US$ 2,073,000
(D3) Structure no ha 1 Vent: 1 0.82 2 Vent 1 0.93 4 Vent 1 1.17 6 Vent 1 1.29 4.21 7,400,000 BDT 31,154,000 US$ 389,425
Page 123 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
E. Land Reclamation E1: Left Bank (i) Doulatpur‐Zaffarganj 30.0 km2
I. River: Brahmaputra‐Jamuna BDT (i) Embankment construction & repair BDT 588,463,343 (ii) Road Construction BDT 200,327,106 (iii) Structures,(new + repair) BDT 140,600,000 (iv) Bank protection (revetment) BDT 2,044,000,000 Sub‐total Physical work BDT 2,973,390,449 US$ 37,167,381
Land Acquisition (i) Embankment BDT (a)Kaizuri‐ Verakhola 57.25 ha 423,650,000 (b) Hurasagar‐Baghabari 25.35 ha 187,590,000 (c ) Baghabari 4.84 ha 35,797,500 (ii) Bank Protection 24.00 ha 165,840,000 (iii) Structures 4.21 ha 31,154,000 Sub‐Total for Land Acquisition 115.65 ha 844,031,500 US$ 10,550,394
II. River: Padma
1. Protetion work in Left Bank (Harirampur) Temp above LWL and Geobag below LWL 7.00 km 185,000,000 BDT 1,295,000,000 US$ 16,187,500 Total for Physical work (Revetment) = 7.00 km BDT 1,295,000,000 US$ 16,187,500
3. Land Acquisition for Bank Protection (i) Left Bank 7.0 km 24.5 ha
Cost of Land Acquisition 24.5 ha 6,910,000 BDT 169,295,000 US$ 2,116,188
III. Adaptation Work: Repair and strengthening 5.0 km LS BDT 400,000,000 US$ 5,000,000
Padma (i) Bank Protection Work BDT 1,295,000,000 US$ 16,187,500
(ii) Land acquisition 24.5 ha BDT 169,295,000 US$ 2,116,188
Grand Total Physical work I. Physical work for Brahmaputra‐Jamuna: BDT 2,973,390,449 II. Physical Works for Padma BDT 1,295,000,000 III. Adaptation Work and mass dumping BDT 400,000,000 Total Physical works BDT 4,668,390,449 US$ 58,354,881
Land acquisition I. For Brahmaputra‐Jamuna: (115.65 ha) BDT 844,031,500 II. For Padma (24.5 ha) BDT 169,295,000 Total Land acquisition BDT 1,013,326,500 US$ 12,666,581
Grand Total i/c land acquisition BDT 5,681,716,949 US$ 71,021,462
Exchange Rate (US$ to BDT) 1 US$ BDT 80.00
Note: (i) Temporary (Geobag) protection is assumed in upper slope (slope above LWL) of Padma (ii) The land acquisition cost estimated in this package has been superseded in the estimates for Land acquisition and resettlement.
Page 124 September 2013 Technical Designs for Tranch‐1 Work
Estimate for Tranch‐2
Estimate for proposed intervention (Tranch2) 29.05.2013
A. Embankment Length Ht of Embk Cost/m 1. Jamuna (i). Hurasagar‐Shahzadpur (km) (m) (Tranch‐2) (NS) 1.0 3.0 22,279 22,279,395 (NS) 1.0 3.0 22,279 22,279,395 (NS) 4.0 3.5 25,662 102,649,780 Sub‐total (Jamuna, RB) 6.0 BDT 147,208,570 US$ 1,840,107
(ii) Aricha‐Zionpur (Rehabilitation) (40% 0f 4.0 m high embankment) 12.0 4.0 10,361 124,327,584 Sub‐total (Jamuna, LB) 124,327,584 US$ 1,554,095 2. Padma (ii) Dhaka SW Project Embankment (Rehabilitation and strengthening), LB of Padma 17.00 km 10,361 176,130,744 (40% of new construction, 4.0m high embankment) (iii) Dhaka SW Project Embankment (New construction), LB of Padma 8.00 km 4.0 25,902 207,212,640 (4.0m high, wne embankment) Sub‐total (Padma) 383,343,384
B. Road 1. Rural Road (5.5m carriage way+2x1.5m Shoulder) BDT BDT 16.00 km 45,000,000 720,000,000 2. RCC road for NMV (2.8m, 100 mm thick) 16.00 km 4,500.00 72,000,000 3. Grass stone along the slope of crest of embankment (16 km) 16.0 6261 m2/km 39,131 nos/km 270.00 each 169,046,739 Total (Road) 961,046,739
C. Bank Protection Works 1. Bank Protection Works (Jamuna) (i) Enayetpur(Jamuna, Right Bank) 11.00 km 255,500,000 2,810,500,000 (ii) Chouhali, (Jamuna, Left Bank) 3.00 km 255,500,000 766,500,000 (iii) Zaffarganj (Jamuna, Left Bank) 2.00 km 255,500,000 511,000,000 Sub‐total (Jamuna, Protection) 4,088,000,000
2. Bank Protection Works (Padma) (iv) Harirampur (Padma, Left Bank), Protection above LWL and on Berm (cc blocs on filter) 7.00 km 145,000,000 1,015,000,000 Sub‐total (Padma Protection) 1,015,000,000
D. Adoptation Work 5.00 km LS 400,000,000 5,000,000
E. Structures
1. Structures along the left Bank of Padma (i) RCC Regulators (1 vent) 3 nos 19,700,000 59,100,000
Page 125 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
2. Repair of Structures (i) RCC Regulators 2 nos 2,500,000 5,000,000 Total Cost of Structures (new & repair) 64,100,000
E. Land Acquisition (E1) Embankment Length land/km T.land (km) (Ha) (Ha) (1) Jamuna (RB) (i) Hurasagar‐Shahzadpur 1.0 1.02 1.02 (30% land required) 1.0 1.02 1.02 (30% land required) 4.0 1.10 5.10 (30% land required) 7.14 ha (2) Jamuna (LB) (ii)Aricha‐Zionpur (100% of land considered for rehabilitation, Old FFW) 12.0 3.25 39.00 ha Land acquisition for embankment (Jamuna) 46.14 ha 7,400,000 341,454,500 (I). Left Bank (Padma) (i). SW embankment (Rehabilitation and strengthening) (40% of original land for 4.0m emb.) 17.00 1.30 22.10 (ii) SW Project embankment extension, new) 8.00 3.25 26.00 Land for embankment‐Padma 48.10 ha Land acquisition for embankment (Padma) 48.10 ha 7,400,000 355,940,000 (E2) Bank Protection (1) Right Bank (Jamuna) (i) Enayetpur 11.00 km 33.00 (2) Left Bank (Jamuna) (ii) Chouhali 3.00 km 9.00 (iii) Zaffarganj 2.00 km 6.00 Land for protection 16.00 km 48.00 ha
Land acquisition (Bank Protection, Jamuna) 48.00 ha 6,910,000 331,680,000 (3) Left Bank (Padma) (iv) Harirampur (already taken care under Tranch1)
(E3) Land for Structure RCC Regulator (1V) 3 nos 0.82 2.46 ha
2.46 ha 7,400,000 18,204,000
Page 126 September 2013 Technical Designs for Tranch‐1 Work
I. Brahmaputra‐Jamuna BDT US$ (i) Embankment (Hurasagar‐Shahzadpur) 147,208,570 (ii) Embankment Rehabilitation (Aricha‐Zionpur) 124,327,584 (iii) Road construction & ancillary works 961,046,739 (iv) Bank Protection Works 4,088,000,000 Sub‐total Physical work 5,320,582,893 66,507,286
Land Acquisition (Jamuna) (i) Embankment (jamuna) 46.14 ha 341,454,500 (ii) Bank Protection (jamuna) 48.00 ha 331,680,000 Land acquisition (Jamuna) 673,134,500 8,414,181
II. River: Padma (i) Embankment Rehabilitation 176,130,744 (ii) Embankment Construction (new) 207,212,640 (iii) Bank Protection work in Left Bank 1,015,000,000 (iv) Structure 64,100,000 Physical work for Padma 1,462,443,384 18,280,542
Land Acquisition (Padma) (i) Embankment 48.10 ha 355,940,000 (ii) Bank Protection (nil) (iii) Regulators 2.46 ha 18,204,000 Land for embankment (Padma) 374,144,000 4,676,800
III. Adoptation Work (Bank Protection) 400,000,000 5,000,000
Grand Total Physical work I. Physical work for Brahmaputra‐Jamuna: BDT 5,320,582,893 II. Physical Works for Padma BDT 1,462,443,384 III. Adoptation Work BDT 400,000,000 Total Physical works BDT 7,183,026,277 US$ 89,787,828
Land acquisition I. For Brahmaputra‐Jamuna: BDT 673,134,500 II. For Padma BDT 374,144,000 Total Land acquisition BDT 1,047,278,500 US$ 13,090,981
Total physical infrastructure + land BDT 8,230,304,777 US$ 102,878,810
Exchange Rate (US$ to BDT) 1 US$ BDT 80.00
Note: (i) The land acquisition cost estimated in this package has been superseded in the estimates for Land acquisition and resettlement.
Page 127 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
Estimate for Tranch‐3
Estimate for proposed intervention (Tranch3) 29.05.2013
A. Embankment Rate/BDT BDT (i) Dhaleswary‐ Aricha Embankment (New construction), Left bank of Jamuna 23.00 km 32,649 750,933,187 (5.0m high, new embankment) Total (Embankment) 750,933,187
B. Bank Protection Works 1. Bank Protection Works (Jamuna) (i) Chouhali, (Jamuna, Left Bank) 5.00 km 255,500,000 1,277,500,000 (ii) Zaffarganj (Jamuna, Left Bank) 2.00 km 255,500,000 511,000,000 Sub‐total (Jamuna, Protection) 1,788,500,000
2. Bank Protection Works (Padma) (iii) Protection works in Dohar (Padma, Left Bank) 5.00 km 293,825,000 1,469,125,000 (iv) Protection in Louhajang (Padma, Left bank) 2.00 km 293,825,000 587,650,000 (v) Protection in Sureswar (Padma, right Bank) 10.00 km 293,825,000 2,938,250,000 Sub‐total (Padma Protection)‐Padma 4,995,025,000
C. Structures
1. Structures along the left Bank of Jamuna (i) RCC Regulators (1 vent) 3 nos 19,700,000 59,100,000 2. Repair of Structures (i) RCC Regulators 2 nos 2,500,000 5,000,000 Total Cost of Structures (new & repair) 64,100,000
D. Adoptation and Strengthening 5.00 km 80,000,000 400,000,000
E. Land Acquisition (E1) Embankment Length and/km T.land (km) (Ha) (Ha) (i) Dhaleswary‐Aricha embankment extension, (new) 23.00 3.80 87.40 Land for embankment 87.40 7,400,000 646,760,000
(E2) Bank Protection (1) Left Bank (Jamuna) (i) Chouhali 5.00 km 15.00 (ii) Zaffarganj 2.00 km 6.00 Land for protection (Jamuna) 21.00 ha 21.00 6,910,000 145,110,000
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(2) Left and Right Bank (Padma) (iii) Dohar 5.00 km 17.50 (iii) Louhajang 2.00 km 7.00 (iv) Sureswar 10.00 km 35.00 Sub‐total (land)‐Padma Protection 59.50 ha Land for Protection (Padma) 59.50 6,910,000 411,145,000
(E3) Structure (i) RCC Regulator (1‐Vent) 3.00 nos 0.82 2.46 ha
2.46 ha 7,400,000 18,204,000
I. River: Brahmaputra‐Jamuna (i) Embankment 23.00 km 750,933,187 (ii) Protection Work 7.00 km 1,788,500,000 (iii) Structures 64,100,000 Sub‐total ‐Physical infrastructures 2,603,533,187 Land (i) Embankment 87.40 ha 646,760,000 (ii) Protection Work 21.00 ha 145,110,000 (iii) Structures 2.46 ha 18,204,000 810,074,000 II. River: Padma (i)k Ban Protection works 17.00 km 4,995,025,000
Land (i) Bank Protection works 59.50 ha 411,145,000
III. Adoptation 400,000,000
Total Estimated Cost for Tranch‐3 BDT US$ 1. Embankment (Jamuna) 750,933,187 2. (a) Bank Protection (Jamuna) 1,788,500,000 (b) Bank Protection (Padma) 4,995,025,000 3. Structure 64,100,000 4. Adotation & Strengthening 400,000,000 Sub‐total Physical Infrastructure 7,998,558,187 99,981,977 5. Cost of Land (i) Embankment (Jamuna) 87.40 ha 646,760,000 (ii) Bank Protection (Jamuna) 21.00 ha 145,110,000 (iii) Bank Protection (Padma) 59.50 ha 411,145,000 (iv) Structure/Regulators 2.46 ha 18,204,000 Sub‐total for land 170.36 ha 1,221,219,000 15,265,238 Total physical Infrastructure + Land 9,219,777,187 115,247,215
Exchange Rate (US$ to BDT) 1 US$ BDT 80.00
Page 129 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
Basic Element rates used for the estimate (Sample)
1. Base (embankment) Excavation BDT 166.00 m3
2. Dredged Sand/Earth from River for embankment construction BDT 191.00 m3
3. Clay lining BDT 238.00 m3
4. Supply, fill, sewing and staking geobags (125 kg) BDT 209.00 each
5. Supply, fill, sewing and staking geobags (250 kg) BDT 390.00 each
6. Dumping geobag from properly positioned barge BDT 387.00 m3
7. CC block (200x200x300mm) BDT 379.00 each
8. CC block (200x200x200mm) BDT 257.00 each
9. CC block (300x300x300mm) BDT 215.00 each
10. CC block dumping/ placing BDT 1395.00 m3
11. Structural Concrete (18 N/mm2) BDT 8200.00 m3
12. Gras‐stone (400x400x150mm with 4‐holes) BDT 270.00 each
13. 2 Lane Road (5.5m carriage way + 2 – 1.5 m paved shoulder) BDT 45,000.00 m
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Appendix IV: Design Criteria
Main River Flood and Bank Erosion Risk Management Program (MRP)
RIVER BANK PROTECTION, EMBANKMENT AND DRAINAGE WORKS
Design Criteria
September 2013
Page 131 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
Contents 1 Design Criteria ...... 133 1.1 Design Life ...... 133 1.2 Standards and Design Guidelines ...... 133 1.3 General Approach ...... 134 1.4 Hydrology and Hydraulic Parameters ...... 134 1.4.1 River Discharge and Flood Level ...... 134 1.4.2 Flow velocity ...... 136 1.4.3 Wind‐Generated Waves ...... 136 1.4.4 Freeboard ...... 138 1.5 Scour ...... 138 1.6 Design of Erosion Protection Counter‐Measures ...... 138 1.6.1 Slope Protection – River Currents ...... 138 1.6.2 Scour Protection Apron ...... 138 1.6.3 Erosion Protection Waves ...... 139 1.7 Slope Stability...... 139 2 Drainage and Flushing Structures ...... 140 2.1 Draining Capacity ...... 0 14 2.2 Hydraulic and Structural Details ...... 140
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1 Design Criteria
1.1 Design Life
The specified design life of the river bank protection, embankments and drainage and flushing works is 30 years. This does not mean the all the drainage structures and river training works will operate without maintenance over this period of time; periodic repair of drainage infrastructure and/or upgrading of protective works will be required. The definition of a design life pre‐supposes the establishment of a comprehensive monitoring and maintenance program.
1.2 Standards and Design Guidelines The following design standards and guidelines are used for specific aspects of the RTW design, as listed below:
Hydraulic Design Standard Design Manual; Chief Engineer, Design, BWDB Guide Lines and Design Manual for Standardised Bank Protection Structures; Jamuna Test Work Consultants, December 2001 Bureau of Research Testing and Consultancy (BRTC), Bangladesh University of Engineering & Technology 2010: Guidelines for Riverbank Protection. Prepared for Bangladesh Water Development Board, financed through Jamuna‐Meghna River Erosion Mitigation Project (subsequent referred to as BRTC‐2010). US Army Corps of Engineers (USACE), 1994, Hydraulic Design of Flood Control Channels, Engineering Manual EM 1110‐2‐1601. Final report, Main Volume, River Survey Project, FAP‐24, November 1996 Flood Control Embankment and River Bank Protection of the Left Bank of Jamuna River at Nagarpur and Chouhali; Final Report; Directorate of Planning‐1, BWDB and IWM, June 2007 Brahmaputra Flood Embankment Project; (Phulchari to Sirajganj); Definite Project Report; East Pakistan Water and Power Development Authority; leedshill‐DeLeuw Engineers, November 1965. Jamuna Padma Left Bank Project; Final Report; Directorate of Planning‐1, BWDB, July 2007. Quality Control, Monitoring and Impact Assessment of Pilot Dredging of Jamuna River at two Locations, from Sirajganj Hard Point to Dhaleswary Offtake (20km) and near Nalin Bazar (2 km); draft Final Report; IWM.
Geotechnical Design Joseph E. Bowles, 1997: Foundation Analysis and Design, 5th edition, McGraw Hill. Stephen L. Kramer, 1996: Geotechnical Earthquake Engineering, Prentice Hall. . Terzaghi/Peck/Mesri, 1996: Soil Mechanics in Engineering Practice. 3rd edition, John Wiley & Sons. ASTM Standards (Status Dec. 2009): Soil and Rock
In addition, a range of specialized technical publications on scour and bank protection design were consulted including: Przedwojski, Błažejewski, R. and K. Pilarczyk 1995: River Training Techniques. A.A. Balkema, Rotterdam. Pilarczyk, K. 1990: Coastal Protection, Delft University of Technology. Maynord, S., Ruff, J.F. and Abt,, S.R., 1989: Riprap design. Journal of Hydraulic Engineering (ASCE), 115, 7, 937‐949.
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1.3 General Approach
The design flood for the river training works has a return period of 100 years. The RTW must be capable of experiencing the design condition without experiencing significant damage. Under design conditions, the stability of the cover layer and scour protection measures must meet or exceed the required factors of safety specified in US Army Corps of Engineers guideline EM 1110‐2‐1601 (USACE, 1994).
1.4 Hydrology and Hydraulic Parameters 1.4.1 River Discharge and Flood Level
(a) River Discharge
The design flood discharge was determined as the 100‐year discharge based on the historic record of maximum annual discharges at the Bahadurabad gauge for Brahmaputra‐Jamuna and Mawa gauge station.
In Main River Flood and Bank Erosion Risk Management Program (MRP),
The frequency analysis for discharge was calculated on observed discharge for Bahadurabad (Jamuna) and Mawa (Padma) for 1976‐2006.
Frequency Analysis of Maximum Discharge by Log 110 Pearson Method:Bahadurabad 105 100 RP-2 67,086 m3)
95 RP-5 79,835 90 RP-10 87,094 85 RP-20 93,391 80 RP-50 100,804 75 RP-100 105,936 70 Discharge(Thousand 65 60 0 20406080100120 Return Period
Discharge at Bahadarabad (Brahmaputra‐Jamuna)
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Frequency Analysis of Maximum Discharge by Log Pearson Method:Mawa 140
130 m3)
RP-2 88,732 120 RP-5 101,432 RP-10 108,875 110 RP-20 115,478 100 RP-50 123,445 RP-100 129,093
Dischage(Thousands 90
80 0 20406080100120 Return Period
Discharge at Mawa (Padma)
(b) Flood Level
The design flood level is based on the 100‐year estimate from frequency analysis of annual maximum water levels at Sirajganj (SW 49) and Mathura (SW 50.3) for left bank of Jamuna River and Bangabandhu Bridge and Aricha (SW 50.6) in thek right ban for Jamuna River. All levels are still water levels and do not account for wave runup.
WL from June 1945 to September 2012 for Sirajganj, April 1964 to September 2012 for Mathura, January 2000 to January 2013 for Bangabandhu (Jamuna) Bridge and April 1964 to August 2012 has been considered for calculating 100 year WL for different stations of Brahmaputra‐Jamuna River.
River: Brahmaputra‐Jamuna Station HWL LWL 2 year 10 year 50 year 100 year observed observed HWL HWL HWL HWL Sirajganj 15.11 6.05 14.57 13.85 15.20 15.46 Mathura 11.90 2.44 10.18 11.08 11.87 12.20 Bangabandhu Bridge 14.12 5.41 13.19 13.98 14.68 14.97 Aricha 10.76 1.94 9.47 10.26 10.95 11.25
Again WL from April 1965 to August 2012 for Baruria and April 1968 to September 2012 for Mawa stations has been considered for calculating 100 year WL for different locations along Padma River.
River: Padma Station HWL LWL 2 year 10 year 50 year 100 year observed observed HWL HWL HWL HWL Baruria 9.89 1.31 8.31 9.10 9.79 10.08 Mawa 7.09 0.78 6.03 6.68 7.25 7.49
The results are finally verified with the publications available.
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1.4.2 Flow velocity (i) Brahmaputra‐Jamuna Observed flow velocity in Brahmaputra‐Jamuna at Bahadurabad transit from 1990 to 2009 is 1695 numbers. Out of all these measurements of velocity in Bahadurabad the highest of 99.77% is selected as design velocity. The data are placed in the design report.
(ii) Padma The maximum velocity lfrom al the 339 discharge observation at Mawa from January2001 to March 2013 was selected. Out of all these maximum observed velocities the highest of 84.7% is selected as the design velocity for selection of the size of protection element.
The analysis is placed below.
1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 00.35 to 1.00 1.0 to 2.00 2.0 to 3.0 3.0 to 4.0 4.0 to 5.0
Observed velocity Number of % of each group Cumulative % (m/sec) observation 0.35 ‐1.00 107 31.6% 31.6% 1.00 ‐ 2.00 79 23.3% 54.9% 2.00‐ 3.00 101 29.8% 84.7% 3.00‐4.00 48 14.2% 98.8% 4.00‐5.00 4 1.2% 100.0% Total 339
1.4.3 Wind‐Generated Waves Slope protection at the river training works is designed to withstand the 100‐year significant wave condition.
The wave height was calculated by Dennis Grosser from hourly wind data recorded at Chandpur, Comilla, Bogra and Ishurdi in JMREMP.
The analysis of available wind data reveals that in Pabna Irrigation and Rural Development Project (PIRDP) the wave height do not exceed 0.6m. The expected wave period is 2.5 secs.
The available wind data indicate that wave heights at the Meghna‐Dhonagoda Irrigation Project (MDIP) would be in the order of 1 m. The expected wave period is then 3.9 s.
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In Padma Multipurpose Bridge Design Project, wave hindcasting was carried out using the simplified procedures described in the US Army Corps of Engineers Coastal Engineering Manual EM 1110‐2‐1100, 2008. The maximum wave heights at the site are limited by the available fetch. The fetch distance varies with bank location, water level and channel bank position which varies over time due to erosion and accretion of the adjacent chars. It was assumed that shallow vegetated floodplain areas will not contribute to wave generation.
Wave runup is the maximum elevation of wave uprush above the still water level and depends on the deep water wave climate, angle of approach, near‐shore topography, bank type and bank slope. Wave runup (Ru%) is described statistically as the runup level exceeded by i per cent of the incident waves. A value of 2% exceedance is generally used for design of coastal structures (USACE, 2008). This means that under a 100‐year storm condition, 2% of the incident waves would equal or exceed a value of Ru2%. Wave runup was computed for the case of irregular waves approaching to an impermeable 1V:3H bank slope using relations described in River Training Techniques; K.W.Pilarczyk, 1995
Effective Runup is given by
R = τrp. rβ . Rn where, τrp is the reduction factor due to slope roughness and permeability rβ is the reduction factor due to oblique wave attack and Rn is the runup on smooth plane slope defined as the vertical wave height above still water level.
Again, Rn 2% = (1.5‐1.75) ξp Hs for ξp < 2.5 Rn 2% = (3.0 ‐ 3.5) ξp Hs for ξp > 2.5 where, Rn 2% = runup which exceeds by 2% waves (for wind waves) ξp = Wave breaking parameter = 1.25 Tp.Tanα. Hs ‐0.5 Hs = significant wave height (m) Tp = wave period (sec) α = slope angle (°)
The Section of embankment
Crest Level : 14.80 m PWD 100 year HWL: 13.90 m PWD R/S slope: 1V:3H C/S slope: 1V:2.5H
In MRP
Wave height is assumed for a 7.5 km fetch, 20 m/sec wind speed [Guideline for River bank Protection; BRTC, BUET and BWDB] and checked with FAP 21 guideline and FAP‐1 documents. wave height = 1.3 m wave period = 2.3 sec
(Halcrow reported maximum wind speed of 18.0 m/sec in Faridpur, Sirajganj, Bogra and Mymensingh, 1994)
(In JMREMP Dennis Grosser analysed wave for the period 1996 to 2005. The maximum wind speed recorded was 18.0 m/sec. Record stations are Comilla, Bogra, Ishurdi and Chandpur.)
Page 137 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
The calculation showing the runup is enclosed as Appendix‐1 and the analysis conducted by Dennis Grosser is enclosed in Appendix‐2. 1.4.4 Freeboard The crest elevation of all embankments that are not intended to be overtopped were determined as follows:
Crest El. = Design maximum elevation of wave uprush (Ru2%) or 1.5 m freeboard whichever is higher. In all the calculation 100 year HWL has been used.
Note: (No flood in the past has attained the 100 year flood limit, 1988 flood attained a return period of 65 year in Jamuna and in Padma, again 1998 flood attained a return period of 40 year in Jamuna and about 50 year in Padma.)
1.5 Scour Scour was determined under a range of discharges and channel pattern scenarios in order to envelope the worst conceivable scour condition at the site. These channel pattern scenarios were based on a careful review of historical data spanning the last 1995‐2012 period and compared with standard literature.
MRP Activities sScour level were based partly on a record from 1995 to 2011/2012 and surveyed bed elevations in the general vicinity of the work site in October 2012 and March 2013.
Design Scour Scour was estimated for a range of discharges including bankfull discharge up to the 100‐year flood. Brahmaputra‐Jamuna being a braided river, attention is given to assess the flow along a particular channel. The Padma river near Baruria and opposite to Faridpur flowing in multiple channel is also assessed accordingly.
1.6 Design of Erosion Protection Counter‐Measures 1.6.1 Slope Protection – River Currents The bank slopes will be protected against erosion from river currents to prevent damage to the underlying fine material. The design of the slope protection (including cover layer, filter layer or geotextile) will be in accordance with accepted methods described in BRTC‐2008.
The stable size of protection element (cover layer) against river currents is determined using the Pilarczyk equation as suggested in Guideline for River bank Protection; BRTC, BUET and BWDB. 1.6.2 Scour Protection Apron Scour protection aprons will be provided at all river training structures to prevent undermining of the revetment slopes. The design approach will reflect general uncertainties associated with launching aprons and the lack of a complete understanding of the self launching of different scour protection elements. The size and type of materials used in the aprons will be determined using site conditions and design requirements on the Jamuna and Padma River in Bangladesh as prescribed in BRTC‐2008 and the additional experience gained at Jamuna Bridge and other major river training works in Bangladesh.
The nominal volume of geobags required in the apron is determined by assuming the geobags launch on a slope 1V:2H and provide single layer coverage after initial launching. Safety factors is applied to
Page 138 September 2013 Technical Designs for Tranch‐1 Work cover uncertainties. Therefore, the factor of safety for launching apron volumes will be 1.5 for selected design scour conditions. 1.6.3 Erosion Protection Waves The stable block size for slopes exposed to wave attack is determined by Pilarczyk’s relation (CIRIA 2007):
b Hsξz Dn Δm Ψu Φsw cosα
In which, Dn is the nominal thickness of the protection element [m], Hs is the significant wave height b 1/2 [m], is the wave similarity parameter (=tan α * 1.25Tm/Hs ), α is the slope angle, Tm is the mean ξz wave period [s], Δm is the relative buoyant density of the protection unit [‐], Ψu is the system specific stability upgrading factor [‐], and φsm is the stability factor for wave loads. The assumed design parameters for hand placed cc blocks over geotextile filter are as follows:
The system specific stability upgrading factor (Ψu) is 2.00. Stability factor (φsm) is 2.25 which is the low end of the range between 2.25 and 3.0.
1.7 Slope Stability Slope stability analysis is carried out at the main RTW structures to locate critical sections of the river banks and to ensure the RTW slope protection will be geotechnically stable under various loading scenarios. The slope stability analysis will distinguish two cases: (i) slopes formed by self launching aprons, (ii) overall slopes to deepest scour level.
Four loading cases (LC) on the RTW structures will be analyzed: LC1: dead load, traffic load, lateral earth pressure, hydraulic pressure (including regular percolation); LC2: Additional rare occurrences or temporary conditions during construction will be added to LC1;
The safety factors that will be adopted against failure for loading condition on the RTW slopes will reflect the importance and the risk of exposure of the upper dredged slopes and the deeper slopes formed by self‐launching aprons. For the upper dredge slopes and the overall slope stability safety factors are indicated below.
Table 1: Safety factors for geotechnical assessment of river training works
Loading Case LC1 LC2 Factor of Safety 1.4 1.3
The slopes formed by self‐launching aprons are commonly at the limit state of stability and consequently cannot be treated in the same way. The analysis of slope stability will determine the factor of safety and the limit conditions after which failure is expected. Limit state of stability means the factor of safety is close to 1 for the highest loading conditions. To prevent a slip plane encroaching into the slope section above, the apron have to leave wide berms after launching. The launched slopes need to be monitored regularly in order to be able to provide reinforcement (adaptation) in a timely manner.
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2 Drainage and Flushing Structures
2.1 Draining Capacity
The size of a regulator is fixed on the expected runoff 1 in 10 year. In the present case the runoff suggested in IECO publication has been used as check with 20% increase over the suggested runoff.
2.2 Hydraulic and Structural Details As per BWDB design Guidelines.
Attachments
Attachment‐1: Overtopping of Embankment Attachment‐2: Wave Analysis
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Attachment‐1: Overtopping of Embankment
Embankment Crest in Kaizuri‐Hurasagar Overtopping of embankment
Section of Embankment Crest Level :14.80m new PWD (suggested by Technical Committee, R/S Slope :1V:3H on recommendation of model study) C/S Slope: 1V:2.5H
Effective run‐up, R =τrp.rβ.Rn [River Training Techniques; KWPilarczyk, 1995] (Page‐446) where
τrp is the reduction factor due to slope roughness and permeability
rβ is the reduction factor due to oblique wave attack
Rn is the run‐up on smooth plane slope defined as the vertical wave height above still water level Again 2% Rn = (1.5 ‐ 1.75)ξp Hs for ξp < 2.5 and 2% Rn = (3.0 ‐ 3.5) Hs for ξp > 2.5 2% Rn = the run‐up which is exceeded by 2% waves (for wind waves) ‐0.5 ξp = Wave breaking parameter = 1.25xTp tanα Hs
Hs = Significant wave height [m]
Tp = Wave period [sec] α = side slope angle [°]
Data W =13.3m new PWD (still water level, Model generated)
Hs = 1.3 m (Wave height and Wave period from BUET‐BRTC)
Tp = 2.3 sec α = 18.43 ° For slope of embankment 1V:3.0H
‐0.5 ξp = 1.25xTp tanα Hs 0.834 [‐](slope 1V:3H) 2% Rn run‐up exceeded by 2% of waves
Therefore, (run‐up exceeded by 2% of waes) 2% Rn = (1.5 ‐ 1.75)ξp Hs = 1.63 m (with slope of 1V:3H) (higher numerical value is used for the calculation)
Considering smooth surface ( τrp = 1.0) and angle of wave attack (β = 30°):
R =τrp.rβ.Rn = 1.50 m (With slope of 1V:3H, and β =30°)
Page 141 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
Reduction Factor for Slope Surface Roughness and permeability (Table: 6.27, Page‐448, River Training Techniques; Pilarczyk)
Cover layer τrp Asphalt, smooth concrete 1.00 Concrete blocks, Open stone asphalt, grouted stone, grass mats 0.95 Pitched stone 0.9 Rough, permeable block mats, gravel, gabion mattress 0.7 ‐ 0.8
Riprap (minimum thickness 2Dn50)0.5 ‐ 0.6
Reduction Factor for oblique wave attack, after SNIP (1983) (Table: 6.28, Page‐448, River Training Techniques; Pilarczyk) Angle β° 0102030405060
rβ 1.00 0.98 0.96 0.92 0.87 0.82 0.76
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Attachment 2: Wave Analysis by Dennis Grosser
1. General
When wind blows over water the water surface starts to move and form waves. Waves are the result of shear stress between moving air (wind) and water surface. The energy of the moving air is transferred to water particles. These water particles start to move in the same direction the wind blows.
Waves are defined by wave height H, wave period T, wave lengths L, and direction (see Figure 1‐1). Waves are often generated far from the place where they are observed. However, related wind speed and duration can be derived from the observed wave height, wave period and wave direction. Uncertainties in the relationship between wind and waves result from the fact that waves can be transferred and reflected during travelling. If the waves are travelling through areas with shallow water they are in contact with the bottom and start changing direction and height called shoaling and refraction. The calculation remains simple as long as the waves travel in the deep‐water zone (d > 2 L, where d is the water depth and L the wave length). Due to refraction and shoaling the wave height is decreasing and the wavelength is changing. The wave period remains the same.
Figure 1-1: Definition of terms – elementary, sinusoidal, progressive wave (CEM Figure II- 1-9)
Waves observed in oceans, lakes, or rivers are not single regular waves. Observed waves in nature are the results of a superimposing process of different single waves generated on different locations with different wind speed and durations. They form a spectrum of waves with different wave height, wave periods and wavelength. sThi wave spectrum is described by a significant wave height Hs (the average of the upper third of all observed waves). The wave spectrum contains of different waves with different energy density (see Figure 1‐2).
Page 143 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
Figure 1‐2: Sketches of wave spectral energy and energy density(CEM Figure II‐1‐35, Chakrabarti 19871
The frequency at the peak is called the peak frequency fp. The wave peak period Tp is then 1/fp. The mean wave direction is then the mean value of the directions and describes the mean direction of the wave spectrum. Figure 1‐3 shows a schematic for a two‐dimensional wave spectrum.
JONSWAP (Joint North Sea Wave Project, Hasselmann et al., 19732) developed a wave spectrum for fetch‐limited seas, which can be expressed by the following formulae:
It can be assumed for observed waves with periods between 3 and 25 seconds that they are generated by wind. The following Figure 1‐4 shows some equations related to waves:
1 Chakrabarti, S.K., “Hydrodynamics of Offshore Structures”, WIT Press, Southampton, UK. 2 Hasselmann et al., 1973, „Measurements of Wind‐Wave Growth and Swell Decay During the Joint North Sea Wave Project (JONSWAP)”, Deutsche Hydrograph. Zeit., Ergänzungsheft Reihe A (8°), No. 12.
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Figure 1-3: A schematic for a two-dimensional wave spectrum (E(f, ) (CEM Figure II-1- 33))
Figure 1-4: Summary of linear (Airy) wave theory – wave characteristics (CEM Figure II- 1-9)
Page 145 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
Figure 1‐5 shows the different wave phases, the velocity and the acceleration of water particles of the waves for deep water conditions. If the waves are entering the transition zone they start to transform and become more elliptic because the particles are influenced by the bottom.
Figure 1-5: Wave phases
2. Generation of Waves:
The generation of waves depends on fetch length, wind speed and duration of wind event. The fetch length is the length of the water surface, for example of a lake or an ocean the wind is blowing across. It is the length of the water surface, where the wind can transfer energy to the water. Wave generation can be limited by (i) the duration of the occurring wind (duration limited) or (ii) the length of the water surface of ocean/lake (fetch limited). Wind must blow for a certain time to develop the full wave height for the given fetch length. Only after some time of blowing across the surface, sufficient energy is transferred into the water surface to generate the full wave height.
The time it takes for waves to travel the fetch length can be calculated with the following formulae (CEM, II‐2‐35): X 67.0 t 23.77 ,ux gu 33.034.0
where X is the fetch length and uw is the wind speed.
Figure 2‐1 shows the minimum time for different wavelength and different wind speeds. It shows for example that a two km wide water surface requires minimum 25 m/s wind speed for 30 min to generate the full wave height. For a five km wide water surface is requires about 55 minutes of 20 m/s wind.
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Figure 2‐1: Equivalent duration for wave generation as a function of fetch and wind speed (CEM figure II‐2‐3)
JONSWAP (Joint North Sea Wave Project, Hasselmann et al., 19733) gives formulas to calculate the have heights and wave period: ~ ~ 5.0 H s 00178.0 F ~ ~ 3.0 Tp 352.0 F where the non‐dimensional parameters are: ~ 2 s /UgHH Ws ~ 2 /UgFF W ~ 2 p /UgTT Wp where Uw is the wind speed, F is the fetch length, Hs the significant wave height, and Tp is the peak wave period.
Figure 2‐2 to Figure 2‐5 show the diagrams for estimating wave height and period for known wind speed and duration. Figure 2‐6 and Figure 2‐7 summarize these diagrams for some wave heights and wave periods for fetch and duration limited wave climates, while Figure 2‐8 gives some wave heights for fetch limited wave climate for six different wind speeds. It shows for example that the generated wave for a 5 km wide water surface and 15 m/s wind speed is 60 cm high. However, this wave only occurs if the wind blows for a minimum of 45 minutes (see Figure 2‐1).
3 Hasselmann et al., 1973, „Measurements of Wind‐Wave Growth and Swell Decay During the Joint North Sea Wave Project (JONSWAP)”, Deutsche Hydrograph. Zeit., Ergänzungsheft Reihe A (8°), No. 12.
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Figure 2-2: Fetch-limited wave heights (CEM Figure II-2-23)
Figure 2-3: Fetch-limited wave periods (CEM Figure II-2-24)
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Figure 2-4: Duration-limited wave heights (CEM Figure II-2-25)
Figure 2-5: Duration-limited wave periods (CEM Figure II-2-26)
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Figure 2-6: Wave heights and period for fetch limited waves
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Figure 2-7: Wave heights and period for duration limited waves
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Wave height fetch limited
35 m/s 3 30 m/s
2.5 25 m/s 20 m/s 2 15 m/s 10 m/s 1.5
1 Wave heightWave [m]
0.5
0 0 5 10 15 20 Fetch length [km]
Figure 2-8: Wave heights for fetch limited wave climate
3. Transition zone (Shoaling and Refraction)
As already mentioned above, the water depth influences waves. If the water depth becomes less than 0.5 H, wave height and wavelength are changing. If waves are not already running perpendicular to the bank line the wave direction will turn towards a direction perpendicular to the bank line. This change in direction is called refraction and is caused when waves come into contact with the bottom and consequently slow down their movement. At the same time and for the same reason the wave height will change. This is called shoaling. The formula for calculating the wave height is:
where Ks and Kr are the coefficient for shoaling and refraction. Both coefficients are smaller than unity and reduce the wave height. The wave period remains unchanged.
At a certain point the waves are breaking. The breaker criteria for shallow water conditions is:
It means that the wave particles at the crest are nfaster tha the wave itself and the wave becomes unstable. The angle of the wave crest is less than 120°.
However, waves can also break in deep water. The criteria are the same than for shallow water, but the water depth has no influence in the wave breaking. The formulae is
Wave breaking on deep water condition can also occur as white capping, where the wave itself remains stable and only the upper part of the wave breaks. This might happen with strong winds on high waves, where the wind accelerates only the upper part of the wave and this part is detached from the lower part of the wave.
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4. Wind Conditions in Bangladesh
4.1 General Figure 4‐1 shows the distribution of heavy thunderstorms around the world. It can be seen that Bangladesh is located in an area with a higher risk of thunderstorms. These thunderstorm can generate fast winds, but will only create high waves, if the duration of the storm is long enough and the direction is sufficient to have a long fetch to generate high waves.
Figure 4-1: Distribution of heavy thunderstorms around the world
4.2 Previous Studies Halcrow (1994)4 investigated wind data in 1994. The maximum wind speed equal to or exceeding 30 knots recorded was as followed:
Table 4-1: Wind speed and direction reported by Halcrow (1994)4: Location Wind speed [knots] Wind speed [m/s] Direction [°] Faridpur 35 18.0 340 Faridpur 30 15.4 150 Sirajganj 35 18.0 150 Bogra 30 15.4 200 Bogra 30 15.4 360 Bogra 30 15.4 130 Mymensingh 30 15.4 50
The following wind frequency chart (see Figure 4‐2) shows a 10‐hour wind measurement. It can be seen that wind of 30 knots (15 m/s) blows for 30 minutes. Halcrow estimated a maximum wave height of 1.0 m with a period of 3.0 s. Unfortunately Halcrow gives no information about the duration of the wind speed.
4 (Sir William Halcrow & Partner ltd., River Training Studies of the Brahmaputra River, Master Plan Report, 1994, Technical Annexes, Annex 4 Design and Construction)
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To generate wave heights of 1.0 m as reported by Halcrow a wind of 30 knots/15 m/s blowing over 20 km fetch length for about 3 hours is necessary. A wind of 15 knots/8 m/s is necessary for about 9 hours. The wave period is then 3.5 s.
Figure 4-2: Wind measurement recorded by Halcrow (1994)4
4.3 JMREMP Study We have received some wind data from the Bangladesh Meteorological Department for the four wind stations at Bogra, Ishurdi, Chandpur, and Comilla (see Figure 4‐3). The data sets contain 10 years of measurements. Measurements were taken 8 times a day for 10 minutes and the average was recorded.
We have analysed the data as follows: 1. In a first step we have divided the wind data for each side into 4 sectors: North, East, South and West. We have plotted the monthly measured wind speeds per sector in Figure 4‐4 to Figure 4‐ 7. The relevant JMREMP subproject is plotted in the centre. This allows relating wind direction and orientation of riverbank protection work build under JMRMEP. 2. In a second step the data were analysed for each 10°‐section. Figure 4‐8 to Figure 4‐11 shows the results with the number of samples for every section, the maximum wind speed in knots and the average of the upper third of the measurements (not taking the “0”‐measurements into account).
The findings are: 1. During the dry season the wind comes mainly from North‐Western directions, while the wind during the monsoon season comes from South‐Eastern directions. 2. e Th riverbank protection work at both sites is largely oriented in north‐south direction and would be directly hit only through westerly winds (MDIP) and easterly winds (PIRDP). 3. In general winds from northerly directions occur during the dry season from September to June. During this period water levels are mostly low. Winds from southerly directions normally can be observed during the monsoon seasons.
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4. The maximum observed wind speed for Comilla was 31 knots (15 m/s), for Bogra and Ishurdi 35 knots (18 m/s), and for Chandpur 36 knots (18 m/s). Table 4‐2 shows the average wind speeds for the four locations. 5. There are substantial periods when no wind was measured. These periods occur all over the year and are not limited to the monsoon or dry season. During the whole period of measurements (10 years) 61% of all measurements at Chandpur were measurements without wind, 33% at Comilla, 34% at Ishurdi and 51% at Bogra.
Table 4-2: Average Wind Speed from 1996-2005
Chandpur Comilla Bogra Ishurdi Average wind speed 1996‐2005 with zero‐values 16 May ‐ 31 October 1.15 3.22 1.97 2.39 1 November ‐ 15 May 0.95 1.97 1.52 1.89 Average wind speed 1996‐2005 without zero‐values 16 May ‐ 31 October 2.69 4.06 3.63 3.40 1 November ‐ 15 May 2.70 3.62 1.96 3.04
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Figure 4-3: Location of Wind Stations and Sites
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Figure 4‐4: Wind in Bogra from 1996 to 2005
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Figure 4‐5: Wind in Ishurdi from 1996 to 2005
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Figure 4‐6: Wind in Chandpur from 1996 to 2005
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Figure 4-7: Wind in Comilla from 1996 to 2005
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Bogr a, Wind Dir e ction 0 35012 0 0 0 10 340 20 Bogra 330 30 10 0 0 0 320 40 Direction Samples Percent aver(1/3) max 310 8000 50 0 530 2 5.06 18
300 6000 60 10 6 0 3.57 4
290 4000 70 20 6 0 7.00 9 30 21 0 4.29 6 280 2000 80 40 12 0 8.75 12 270 0 90 50 903 3 5.45 18 260 10 0 60 1 0 2.00 2 250 110 70 3 0 4.00 6
240 12 0 80 9 0 4.00 4
230 13 0 90 3,597 12 6.08 34 220 14 0 100 3 0 6.00 6 210 150 200 16 0 110 1 0 10.00 10 19 0 170 18 0 Samples 120 7 0 3.00 4
130 3,646 12 5.26 17 140 6 0 4.00 4 150 12 0 5.00 7 160 3 0 8.00 8 Bogra, Wind Speed 0 350 40 10 340 20 170 1 0 2.00 2 330 35 30 180 1,546 5 5.19 15 320 40 30 310 50 190 2 0 4.00 4 25
300 20 60 200 - - 0.00 0
290 15 70 210 60 0 4.95 8 10 220 23 0 4.25 6 280 80 5 230 991 3 5.73 23 270 0 90 240 1 0 2.00 2 260 10 0 250 1 0 3.00 3 250 110 260 1 0 2.00 2 240 12 0 270 1,284 4 4.27 25 230 13 0 280 - - 0.00 0 220 14 0 210 15 0 290 - - 0.00 0 200 16 0 19 0 17 0 aver(1/3) 300 - - 0.00 0 18 0 max 310 1,590 5 4.83 28
320 - - 0.00 0 330 10 0 4.00 5 340 4 0 3.00 4 350 10 0 2.00 2 360 530 2 5.06 18 Samples 14,290 49 Average/day 3.92 0-values 14,910 Figure 4-8: Wind Speed and Direction at Bogra 0-value % 51.1
(1996-2005)
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Ishurdi, Wind Direction 0 350 10 340 12 0 0 0 20 330 30 10 0 0 0 320 40 Ishurdi 310 8000 50 Direction Samples Percent aver(1/3) max 300 60 6000 0 2,407 8 4.36 16 290 4000 70 10 5 0 3.50 4 280 2000 80 20 3 0 2.00 2 270 0 90 30 32 0 9.13 14
260 10 0 40 122 0 4.21 12
250 110 50 512 2 4.77 17
240 12 0 60 11 0 5.00 7
230 13 0 70 4 0 2.00 2 220 14 0 80 9 0 2.67 4 210 150 200 16 0 90 1,448 5 6.16 17 19 0 170 18 0 Samples 100 1 0 10.00 10
110 - - 0.00 0 120 1 0 4.00 4 130 4,401 15 6.12 18 140 38 0 5.92 10 Ishurdi, Wind Speed 0 350 40 10 150 4 0 3.00 4 340 20 330 35 30 160 11 0 5.75 10 320 40 30 310 50 170 - - 0.00 0 25 180 4,807 16 5.45 15 300 20 60 190 4 0 8.00 8 290 15 70 10 200 3 0 4.00 4 280 80 5 210 94 0 5.28 10 270 0 90 220 406 1 5.24 12 260 10 0 230 998 3 5.42 35 250 110 240 6 0 8.00 8 240 12 0 250 6 0 2.00 2 230 13 0 260 5 0 5.00 6 220 14 0 270 1,793 6 5.05 25 210 150 200 16 0 19 0 170 aver(1/3) 280 27 0 4.11 10 18 0 max 290 1 0 2.00 2
300 15 0 4.50 5 310 1,691 6 12.50 16 320 239 1 5.36 14 330 162 1 5.78 15 340 6 0 3.50 4 350 1 0 2.00 2 360 2,407 8 4.36 16 Samples 19,273 66 Average/day 5.28 0-values 9,927 Figure 4-9: Wind Speed and Direction at Ishurdi 0-value % 34.0 (1996-2005)
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Comilla, Wind Direction 0 35012000 10 340 20 330 30 10000 320 40 Comilla 310 8000 50 Direction Samples Percent aver(1/3) max 300 60 6000 0 2,494 9 5.00 31 290 4000 70 10 6 0 5.50 6 280 2000 80 20 1 0 4.00 4 270 0 90 30 21 0 3.25 4 260 10 0 40 48 0 5.88 15
250 110 50 513 2 5.68 15
240 12 0 60 9 0 4.00 2
230 13 0 70 5 0 3.50 4 220 14 0 80 32 0 5.54 8 210 150 200 16 0 19 0 170 90 805 3 3.38 25 18 0 Samples 100 11 0 4.00 5 110 5 0 3.00 4 120 10 0 3.00 3 130 1,624 6 5.69 15 Comilla, Wind Speed 140 184 1 5.66 10 0 350 40 10 340 20 150 115 0 8.32 19 330 35 30 160 21 0 7.00 18 320 30 40 310 50 25 170 35 0 6.00 10 300 20 60 180 10,260 35 7.60 27 290 15 70 10 190 6 0 5.00 5 280 80 5 200 21 0 5.50 8 270 0 90 210 304 1 8.26 14 260 10 0 220 31 0 7.84 16 250 110 230 526 2 5.07 15 240 12 0 240 7 0 5.00 8 230 13 0 250 8 0 4.00 6 220 14 0 210 150 260 2 0 4.00 4 200 16 0 aver(1/3) 19 0 170 18 0 max 270 790 3 5.57 27 280 6 0 3.50 4 290 14 0 3.60 5 300 21 0 4.00 6 310 1,053 4 4.47 24 320 51 0 4.18 10 330 8 0 3.67 4
340 261 1 4.59 15
350 3 0 4.00 4
360 2,494 9 5.00 31 Samples 19,311 66 Average/day 5.29 0-values 9,889 0-value % 33.9
Figure 4-10: Wind Speed and Direction at Comilla (1996-2005)
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Chandpur, Wind Direction 0 35012000 10 340 20 330 30 10000 320 40 310 8000 50 Chandpur
300 6000 60 Direction Samples Percent aver(1/3) max
290 4000 70 0 1,146 4 3.65 16
280 2000 80 10 6 0 7.00 9
270 0 90 20 66 0 28.55 36 30 28 0 18.78 36 260 10 0 40 8 0 27.00 30 250 110 50 150 1 5.30 31 240 12 0 60 5 0 2.00 2 230 13 0
220 14 0 70 8 0 3.00 5 210 15 0 80 6 0 4.00 4 200 16 0 19 0 170 90 251 1 4.88 25 18 0 Samples 100 4 0 2.00 2 110 77 0 2.67 6
120 73 0 4.13 5
130 2,085 7 11.88 22 Chandpur, Wind Speed 0 140 247 1 6.32 15 350 40 10 340 20 150 28 0 3.60 5 330 35 30 320 40 30 160 166 1 3.36 6 310 50 25 170 7 0 2.00 2 300 20 60 180 3,794 13 4.49 20 290 15 70 10 190 5 0 3.00 3 280 80 5 200 29 0 3.82 8 270 0 90 210 316 1 3.35 11 260 10 0 220 129 0 3.67 9 250 110 230 565 2 4.90 12 240 12 0 240 - - 0.00 0 230 13 0 250 9 0 3.67 5 220 14 0 210 15 0 260 9 0 3.67 5 200 16 0 aver(1/3) 19 0 17 0 270 155 1 4.72 20 18 0 max 280 1 0 1.63 2 290 8 0 2.00 2 Note: The max for Chandpur 310° were taken out, because it 300 3 0 2.00 2 looked wrong (too high, max was 60 and the second highest 310 1,748 6 4.14 25 was 25). The max for Chandpur were taken out, because there 320 27 0 3.33 9 it looked wrong (too high, max was 90 and the second highest was 20) 330 5 0 3.00 4 340 143 0 2.33 6 350 - - 0.00 0 360 1,146 4 3.65 16 Samples 11,307 39 Average/day 3.10 0-values 17,893 Figure 4-11: Wind Speed and Direction at 0-value % 61.3 Chandpur (1996-2005)
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The Coastal Engineering Manual (CEM) provides a figure to transfer wind measurement from a 10 minutes measurement to a 1 hr measurement, which is used for calculation of wave heights (see Figure 4‐12). It shows that the wind speed measured for 10 min is 5% higher than the 1‐hr wind. The duration of winds still remains uncertain. Due to this it is very difficult to estimate the relevant design wave height and wave period. It would be very helpful to have frequency duration curves for both sub‐ projects.
Figure 4-12: Ratio of wind speed of any duration ut to 1-hr wind speed U3600 (Figure II-2-1)
5. Waves on Rivers
The flow velocity of rivers has to be taken into account for calculating the wave height. The wind is transferring energy into the water based on the sheer stress. If the wind speed and the flow velocity have the same direction the sheer stress becomes less, because the difference in velocity is less. To calculate the wave heights for these cases the flow velocity has to be deducted from the wind speed if they both have the same direction. If the direction is opposed to each other the velocities need to be summed up.
For the major rivers in Bangladesh the highest measured flow velocities over longer areas are 2 m/s close to the surface even though locally peaks of up to 4m/s can be observed. Assuming a fetch length of 5 km and a constant wind of 17 m/s acting for 20 minutes on the river surface, the generated wave will have a height of 0.7 m, a wave period of 2.8 s and a wavelength of 12.5 m. The transition zone begins at a depth of 6.25 m. Superimposing the flow velocity v = 17 m/s and the wind speed of w = 2 m/s and calculation the wave height result is a height of 0.8 m with a period of 3 s. The wave length is then 13.6 m and the transition zone starts at 6.8 m, which is a 0.1 m higher and 1 m longer wave. If the wind comes from the same direction then the current the wave height is 0.6 m with a period of 2.7 s. The wave length is 11.3 m.
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6. Waves at PIRDP and MDIP
The characteristics of the rivers on front of both sub‐projects are very different. The Jamuna River at PIRDP is dominated by chars and channels whereas the Meghna/Padma River at MDIP is a large channel, in places up to 5 km wide. The single channels of Jamuna River are 500 – 800 m wide and change width and depth during every monsoon season. Table 6‐1 summarizes our wave collection for different parameters.
Table 6-1: Wave height calculation for several wind speeds and fetch length Jonswap
Fetch [m] uw [m/s] tx,u [s] Hs [s] Tm [s] Tp Lo 150,000 7 918 1.5 4.8 5.5 47.2 100,000 7 700 1.3 4.3 4.9 37.0 100,000 5 785 0.9 3.7 4.3 28.3 50,000 6 464 0.8 3.3 3.7 21.6 20,000 16 180 1.3 3.7 4.2 27.3 20,000 14 188 1.1 3.5 4.0 24.5 20,000 12 198 1.0 3.3 3.8 21.7 20,000 10 211 0.8 3.0 3.5 18.7 20,000 9 219 0.7 2.9 3.3 17.2 20,000 7 238 0.6 2.6 3.0 14.1 20,000 5 267 0.4 2.3 2.6 10.8 20,000 4 288 0.3 2.1 2.4 9.0 20,000 3 318 0.2 1.9 2.2 7.2 15,000 16 148 1.1 3.4 3.9 23.0 15,000 9 180 0.6 2.7 3.1 14.5 10,000 17 111 1.0 3.0 3.5 18.9 10,000 8 143 0.5 2.3 2.6 10.3 5,000 19 67 0.8 2.6 3.0 13.6 5,000 17 70 0.7 2.5 2.8 12.5 5,000 15 73 0.6 2.4 2.7 11.3 5,000 10 83 0.4 2.0 2.3 8.2 2,000 17 38 0.4 1.9 2.2 7.2 2,000 14 40 0.4 1.7 2.0 6.2 2,000 10 45 0.3 1.5 1.7 4.7 2,000 8 49 0.2 1.4 1.6 3.9
Uw = wind speed, tx_u = necessary time needed for full wave height, Hs = significant wave height, Tm = Mean Period, Tp = Peak Period, L0 = Wave length (deep water conditions)
PIRDP:
Due to the occurrence of channels and chars the wave climate is characterized by cross‐seas. Waves are travelling through channels and interact. Observations have shown that waves are normally short and quiet steep and break (see Figure 6‐1). The maximum fetch length for northern and eastern winds is 5 km during the monsoon season and the water depth is then 7 m or more, depending on the morphological changes in the river from year to year (the location and size of the chars can vary). During the dry season the maximum fetch from these directions is 2 km. The maximum fetch for southern directions parallel to the bank can become 20 km depending on the water levels. During the dry season the fetch is 10 km.
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Figure 6-1: Fetch length PIRDP
Table 6‐2 shows the calculated maximum wave height for different direction for the dry and the monsoon season. The table also shows the time required for full energy transfer. The maximum wave height for the dry season is 0.45 m coming from South with a period of 2.3 s. The transition zone starts at a depth of 5.2 m. During monsoon season the wave height is 0.7 m with a period of 2.8 s also coming from South. The transition zone starts at a water depth of 6.3 m. The required wind duration for its generation is 92 minutes. This wind with a speed of 24 knots was only recorded one time within 10 years of data. The next lowest wind speed was 18 knots. This wind would generate a wave with a height of 0.4 m and a period of 2.3 s.
For a wind speed of 8 m/s and a fetch length of 2 km the calculation of the wave height is like the following bases an the formulae given in section:
2000 67.0 t 23.77 min49 ,ux 81.98 33.034.0 ~ 2 /UgFF W ~ 2 UgF W 6.306/2000 ~ 5.0 Hs 03.06.30600178.0 m
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~ ~ 3.0 0.3 Tp 352.0 F 0.2306.60.352 where the dimensional parameters are: ~ 2 2 Wss gUHH 2.081.9/803.0/ m ~ UTT Wpp 6.181.9/8281.9/ s
Table 6-2: Wave estimation for PIRDP site North East South West Dry season fetch length (km) 2 2 10 ‐ Max. 1 hr Wind Speed (knots(m/s)) 18 (8) 35 (17) 15 (8) 35 (17) Max. Wave height (m) 0.20 0.43 0.45 ‐
Wave Period Tp (s) 1.6 2.2 s 2.3 Wave Length Lo (m) 3.9 7.2 10.3 Time required for full energy transfer 49 min 38 min 143 min
Monson season fetch length (km) 5 5 20 ‐ Max. Wind Speed (knots (m/s)) 20 (10) 35 (17) 10 (5) 35 (17) Max. Wave height (m) 0.4 0.7 0.4 ‐
Wave Period Tp (s) 2.3 2.8 2.6 Wave Length Lo (m) 8.2 12.5 10.8 Time required for full energy transfer 23 min 19 min 2 h
The available wind data indicate that wave heights at PIRDP do not exceed 0.6 m. The expected wave period is then 2.5 s.
MDIP:
There are no chars in the Meghna and Padma River at the MDIP. The fetch length depends on the direction of the wind: If the wind is blowing from northern direction parallel to the bank the fetch is 20 km. The fetch from southern directions is more difficult to estimate. Although the Lower Meghna River is much wider than the upper Meghna River and the Padma River the Lower Meghna there is a bend south of Chandpur. A conservative estimate for the fetch would be 20 km. This is a reasonable fetch for waves from SSW. The fetch can also be assumed to be more than 50 km by assuming there will be defraction and refraction and the waves may travel all the way up towards Chandpur. However, for waves travelling all the way up from the south the waves will hit the bankline on the opposite site bank of the Meghna River. Observed waves were very uniform, long crested, non‐breaking and significant higher than in PIRDP. The highest waves seem to come from southern directions.
The confluence of Padma and upper Meghna could influence the development of waves. Figure 6‐3 shows ACDP (Acoustic Current Doppler Profiler) measurements with the flow velocity at the confluence of the Upper Meghna and the Padma River. It can be seen that the fast current of the Padma flows under the slower current of the Meghna. The water of the Upper Meghna is lighter than the water of the Padma, because it contains less sediment.
Another issue for the wave estimation for MDIP is the influence of tide. The highest waves will probable be generates during low tide with a high flow velocity and wind from southern directions. The sum of these two velocities (flow + wind) is the wind speed to be used for the wave height estimation.
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Figure 6-2: Fetch length MDIP
t = 3.26, 26 July 2001, Q = 22,000, Left Bank to Right Bank
Figure 6-3: Flow velocity at MDIP (confluence Meghna/Padma)
On 11 March the Chandpur Metrological Station measured 31 knots at 15:00 UTC and 18:00 UTC. On 13 March 1998 the station measured 31 knots at 03:00 UTC and 06:00 UTC. On 14 March 1998 they measured 31 knots at 03:00 and 06:00 UTC and 36 knots at 09:00 UTC, which indicated a wind of 16 m/s can be assumed for 6 h or more with all these winds coming from North (20°). The Upper Meghna is meandering very much with a main direction of 20°, but the characteristic of the river is changing about 20 km upstream of the project area. From thereon the river is not meandering anymore and if flows strait to the south. Due to this the fetch length has to be reduced to a very small amount. Taking a fetch of 2 km into account the wave height is 0.35 m, but in fact there will be no waves from this direction in front of the project. The highest observed wind from 360° is 9 m/s. The resulting wave is 0.55 m high with a period of 2.9 s. and a wave length of 13.2 m.
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Between 26 July 2003 at 09:00 UTC and 27 July 2003 at 03:00 UTC the Chandpur Metrological Station recorded 6 knots or more coming from 180° (see Figure 6‐4). Assuming a fetch of 150 km (the fetch reaches from the Bay of Bengal all the way up to Chandpur) and taking the flow velocity into account the generated wave is 1.1 m high with a period of 4.8 s and a wave length of 36 m. The wind would have to blow for 17 hours. This value is very high. The resulting wave would be 1 m/s at the eastern bank. There are no wave measurements available and it is suggested to verify this value by a numerical wave model and wave measurements. Table 6‐3 shows the calculated waves for the three sectors. The highest wave is 1.1 m high coming from South, but this calculation takes a fetch 0of 15 km into account and a wind for 17 h. A wave with a height of 1 m can be generated from western directions with a wind of 13 m/s for 3 hours.
Figure 6-4: Wind speed measured at Chandpur July 2003
Table 6-3: Wave estimation for MDIP site North East South West Dry season fetch (km) 15 ‐ 20 20 Max. 1 hr Wind Speed (knots (m/s)) 18 (9) 31(15) 9 (5) 25 (13) Adjusted wind speed (current) (m/s) 8 15 7 13 Max. Wave height (m) 0.55 ‐ 0.56 1
Wave Period Tp (s) 2.9 3.0 s 3.9 Wave Length Lo (m) 13 14 23.1 Time needed for full energy transfer 180 min 238 m 193 min
Monson season fetch (km) 15 ‐ 20 20 Max. Wind Speed (knots (m/s)) 18 (9) 35 (17) 4 (2) 6 (3) Adjusted wind speed (current) (m/s) 9 15 4 3 Max. Wave height (m) 0.63 ‐ 0.32 0.2
Wave Period Tp (s) 3.1 2.4 2.2 Wave Length Lo (m) 14.5 9 Time needed for full energy transfer 180 min 288 min 318 min
For a wind speed of 20 m/s and a fetch of 10 km it would need 105 minutes of wind to fulfil the conditions for a fetch limited wave climate. The wave would then have a height of 1.1 m with a wave period of 3.7 seconds. The wave length is then 21 m and the transition zone starts at a depth of 10.5 m, with is about 25 m in front of the bank line (slope: 1H : 2.5V). With a fetch of 20 km at the same wind speed it needs 167 minutes to generate a fetch limited wave climate. The generated wave would have a height of 1.6 m and a period of 4.6 seconds. The wavelength would be 32 m.
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During low water the waves will break close to the toe on the dumped cc‐blocks. During high water level the waves will break at the crest (see Figure 6‐5).
Figure 6-5: Water depth at PIRDP (A) and MDIP (B)
The available wind data indicate that wave heights at the MDIP would be in the order of 1 m. The expected wave period is then 3.9 s.
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Appendix V: Road on the Land‐Side of Rehabilitated or Reconstructed Embankment
BOQ of the Proposed Road cum Flood Embankment cum Road (As per Specification & Unit Rate of RHD)
Main River Flood and Bank Erosion Risk Management Program include construction of two roads r under tranche‐1 as shown in Table‐1: Table‐1: Roads under Trenche‐1 Serial Start point End point Length Location
1 Verakhola Kaijuri 13.00 KM Land‐side Bank of Jamuna River 2 Verakhola Baghabari 10.00 KM Land‐side Bank Hurasagar River
The proposed roads would have 5.5 meter bituminous pavement with 1.5 meter hard shoulder in each side. The road would be designed to function not only as part of flood embankment and shelter for flood effected population but would also provide connectivity to growth centers, river ports, local government institutions situated ein th adjoining area of the proposed flood embankments of Pabna, Sirajganj districts. It is obvious that the both roads would be connected to the nearby national highways to meet the growing demand of the traffic in future and to facilitate better connectivity of population.
The geometric features and function of the roads are similar to regional roads. Roads having 3.6 meter pavement width with 1.5 meter hard shoulders are zilla road under Roads and Highways Department connecting District HQ with Upazila HQ and Feeder Road‐Type B Under Local Government Engineering Department connecting Upazilas and Growth Centers. The functions and the specification of the proposed roads are not similar to Zilla Road and Feeder Road‐B. The geometric features of the road particularly, pavement width of 5.5 meter with 1.5 meter hard shoulder on each side and projected traffic on completion of the road are similar to the specification of regional road. Hence the roads would be built as regional roads to meet the growing of projected traffic of the future
Geometric Features and Pavement Components of the Proposed Roads The following standards and specifications, also applicable for regional roads have been followed in designing of geometric and structural components of proposed roads:
Table‐2: Standards and Specifications of Regional Roads Serial Item Value 1 AADT 1500 2 Traffic Growth rate 7% per annum 3 Axle load considered for Pavement Design 4‐5 million axle Load 4 Pavement width 5.5 meter 5 Pavement Type Bituminous 6 Pavement Life 20 years 7 Bituminous Carpeting 40mm 8 Seal oat 12 mm 9 Base 200mm 10 Sub base 200mm 11 Improved Sub Grade 200mm Source: Pavement Design Guide for Roads & Highways Department, April 2005
The feasibility level design of the pavement and geometric elements of the road have been proposed as per minimum requirement of standards and specifications of the Regional Roads. The cross‐section of pavement of the proposed road showing the thickness of different layer of pavement components is given in figure‐4.
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U‐shaped surface drain of 350.00mm wide along with storm water catch pit of 900.00 X900.00mmX1000.00 at 200.00mm apart have proposed to drain off storm/rain water from road surface. In addition, 500.00.mm diameter RCC pipe has been proposed to provide cross‐ wise underneath the pavement for each catch pit to drain off the water to the outer side of the road crest.The plan ofdrain,The cross‐section of the drain, storm water catch pit, have been shown in Figure‐ 1 ,Figure‐2 , Figure‐3 and Lay out Plan of R.C. C Pipe, Embankment Slope Drain and Spill Way are shown in Figure‐5.ely.
Bill of Quantities for the Construction of Proposed Roads The standards and speculations and the rate schedule of regional roads of RHD have been primarily used in preparation of Bill of Quantities (BOQ) items of pavement works. In case of R.C.C and Brick works, standards and speculations of and schedule of rates of LGED have been used. The BOQ cost of Verakhola ‐ Kaijuri road and Verakhola – Baghabari road are TK. 29, 73, 65,474.51 and TK. 22, 93, 07,128.89 respectively. The BOQ of Verakhola ‐ Kaijuri road and Verakhola – Baghabari road are annexed as Annexure‐A and Annexure‐B
Verakhola‐ Verakhola‐Kaijuri Baghabari Road Total SL Description of Items Road (in Taka) (in Taka) (3+ ‐4)
1 2 3 4 5
1 Construction of Pavement 22,37,82,260.00 17,21,40,200.00 39,59,22,460.00
2 Protection of the Slope of the Embankment 2,46,48,000.00 1,89,60,000.00 4,36,08,000.00
3 Surface Drain and Cross Drain
3.1 Construction of 400 mmX550mm Surface Drain 3,73,50,274.49 2,87,30,908.38 6,60,81,254.87
Construction of 750mmX750mm X 750mm Storm 3.2 9,29,279.62 7,18,079.72 16,47,359.33 Water Catch Pit at 200.00 Meter Apart Supplying and Fitting and Fixing of 500.mm R.C.C 3.3 Pipe at 200 meter Apart along the Alignment of 33,48,162.88 31,11,166.17 64,59,329.05 the Drain Construction of RCC Drain on the Slope of the 3.4 73,07,497.52 56,46,702.63 1,29,54,200.15 Embankment
Total Cost of Two Roads 29,73,65,474.51 22,93,07,128.89 52,66,72,603.40
Verakhola-Baghabari Road Length: 10 Kilometer
Bill of Quantities
…………………………..Annexure-B……………………….. Rate Item Code Amount Item Description Measurement Quantity Unit (in No (in Taka) Taka) Construction of Pavement 02/07/02‐ Preparation of Sub‐grade 10000.00m x 5.50m Sqm 85.00 46,75,000.00 RHD (450mm depth) =55,000.00 Sqm
Page 173 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
02/08/01‐ 10000.00m x 5.50m x0.200m Improved Sub‐Grade Cum 804.00 88,44,000.00 RHD =11,000 .00 Cum
02/11/01‐ 2 x10000.00m x1.50m x0.200m Construction of Hard Shoulders Cum 4068.00 2,44,08,000.00 RHD = 6000.00 Cum
03/02/01‐ Sub ‐ base 10000.00m x 5.50m x0.200m Cum 3953.00 4,34,83,000.00 RHD =11,000.00Cum 03/03/02‐ Aggregate base 10000.00m x 5.50m x0.200m RHD Cum 4275.00 4,70,25,000.00 = 11,000.00 Cum
03/06/01(b Bituminous Prime coat (Hand 10000.00m x 5.50m ) ‐RHD Sqm 87.00 47,85,000.00 place) =55,000.00 Sqm
03/07/01(b Bituminous Tack coat 10000.00m x 5.50m ) ‐RHD Sqm 22.00 12,10,000.00 (Labor intensive work) =55,000.00 Sqm
03/11/01(a Premixed Bituminous Carpeting 10000.00m x 5.50m x0.040m 13191.0 Cum 2,90,20,200.00 ) ‐RHD 40mm thick (Av.) =2,200.00 Cum 0
03/12/02‐ 2mm compacted‐ premix 10000.00m x 5.50m Sqm 126.00 69,30,000.00 RHD Bituminous Seal Coat. =55,000.00 Sqm
03/13/01‐ 2 x 10000.00m Lin. Brick on end edging 88.00 RHD =20,000.00 Lin. M M 17,60;000,00.00 Sub Total= 17,21,40,200.00 2.Protection Work of the Slope of the Embankment * 600mm thick blanket of earth cladding with 10,000.00mX12.00 specified cohesive soil on the side slope of m Sqm 110.00 1,32,00,000.00 embankment =1,20,000.00 Sqm ** Supplying and planting vertiver (Binna) grass in 10,000.00mX12.00 bunch of 2 to 3 stem @ of 225 mm all over the m Sqm 48.00 57,60,000.00 side slope =1,20,000.00 Sqm Sub Total= 1,89,60,000.00
3.Surface Drain and Cross Drain 3.1 Construction of 400 mmX550mm Surface Drain
1.15 X 0.7X Earthwork in excavation of drains etc. by 10,000.00 5.02.01‐ excavating earth to the lines, grades and = 0.8050X10,000 Cum 78.42 6,31,281.00 LGED elevation as per drawing, carrying and = 8,050.00 cubic disposing of all excavated materials; meter
Single brick flat soling with 1st class/ PJ bricks, true to level, camber, super elevation and 5.03.01‐ 1.15mX 10,000.00 grade in/c filling the joints with sand (FM Sqm 251.04 28,86,960.00 LGED =11,500.00 Sqm 0.50) in/c cost of all materials complete as per direction of the Engineer‐in‐Charge Brick work with 1st class bricks with 6mm (2X0.375mX0.25m thick cement mortar (1.4) for guard wall of X1.m+2X drain, foot path and median, filling the 0.30mmX0.250mX interstices tightly with mortar, raking out 5.02.03‐ 1m )X 10,000.00 joints, cleaning and soaking bricks at least for Cum 4665.16 1,92,43,785.50 LGED =0.4125X10,000.0 24 hours before use, washing of sand, curing 0 for requisite period, costl of al materials, etc. =4,125.00 Cubic all complete as per direction of the Engineer‐ Meter in‐ Charge. (Minimum F.M. of sand:
Page 174 September 2013 Technical Designs for Tranch‐1 Work
Cement concrete (1:2:4) with Portland cement, coarse sand (F.M 1.80), First class/ 1.15mX075mX PJ brick chips (25mm to 5mm down‐ graded), 10,000.00 5.03.05‐ cost of materials and shuttering, mixing by =0.08625X10,000. Cum 6362.15 54,87,354.38 LGED concrete mixer machine, casting, laying, 00 curing for the requisite period, etc. as per = 862.50 Cum direction of the Engineer‐in Charge 12 mm thick cement plaster (1:4) in drain (0.300m+0.250m+ including cost of materials, washing of sand, 0.550m+0.600m+0 curing for requisite period, maintaining .250m+0.850m)X1 5.12.01‐ proper curvatures of corners, side wall and 0,000.00 Sqm 172.00 4,81,600.00 LGED bottom, costs of all materials, etc. complete, =0.280m X as per direction of the Engineer‐in‐charge. 10,000.00 (Minimum F.M. of sand: 1.2 = 2,800.00Sqm Sub Total= 2,87,30,908.38 3.2 Construction of 750mmX750mm X 750mm Storm Water Catch Pit at 200.00 Meter Apart 1.050m X 1.050mX Earthwork in excavation of drains etc. by 0.975m X 51 5.02.01‐ excavating earth to the lines, grades and =1.0749X51 Cum 78.42 4,299.13 LGED elevation as per drawing, carrying and =54.82 Cubic meter disposing of all excavated materials;
Single brick flat soling with 1st class/ PJ bricks, 1.050m X 1.050mX true to level, camber, super elevation and 5.03.01‐ 51 grade in/c filling the joints with sand (FM Sqm 251.04 14,115.35 LGED =1.1025 SqmX51 0.50) in/c cost of all materials complete as per =56.227 Sqm direction of the Engineer‐in‐Charge Reinforced Cement Concrete in drain work Portland cement , sand (minimum F.M 1.80) 20mm down well graded crushed 1st class brick/picked brick chips (LAA value not exceeding 40) including shuttering, mixing by concrete mixture machine casting , laying, compacting, curing for 28 days, breaking Ist 0.325 Cubic meter class/ picked brick chips etc complete in all RCC in each catch 4.1.10.02.2 respect as per design drawing, design and pit X 51 Cum 7270.00 1,20,314.87 LGED drawing , and direction of Engineer in Charge” = 16.55 Cubic and cylinder crushing strength of concrete meter should not be less than 170 kg/cm2 (suggested mix proportion 1:2:4) excluding reinforcement and fabrication, but including cost of all materials, reinforcement, and its fabrication shuttering, casting curing for 28 days and all incidental charges , 6.051‐ Supplying and Fabrication of M.S high LGED strength deformed bar/Twisted bar reinforcement of size and length for all types of RCC work including straightening the rod, removing ruts, cleaning, cutting, hooking, bending, binding, with supply of 22 B.W.G. GI wire, placing in position, including lapping, spacing and securing them in position by concrete blocks (1:1), metal chairs, etc. 167.97kg of MS complete including cost of all materials, labor, road in each catch kg 67.63 5,79,,350.37 local handling, laboratory test, incidentals pit X51 necessary to complete the work as per =8,566.47 kg specifications, drawings and direction of the Engineer. Laboratory test for physical, strength, elongation % & bend to be performed as peer ASTM. (Measurement will be based on standard weight of 490 lbs./ft3 Chairs, laps and separators will be measures for payment. The cost of these will be included in the unit rate).
Page 175 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
Sub Total= 7,18,079.72 3.3 Supplying and Fitting and Fixing of 500.mm R.C.C Pipe at 200 meter Apart along the Alignment of the Drain Supplying precast RCC pipes(500 mm internal dia,50mm thick) with 12mm downgraded dust free 1st class brick chips (1:2:4)including 12 meter long RCC 6.096‐ pipe joint gap filling in neat cement slurry pipeX51 =792.00 meter 2910.83 23,05,377.36 LGED casting, curing, laying in position, from meter finished type by steel form works as per design , specifications complete as per direction of Engineere‐in Charg Single brick flat soling with 1st class/ PJ bricks, true to level, camber, super elevation and 3.00 m X 1.50mX.6 5.03.01‐ grade in/c filling the joints with sand (FM =4.5 SqmX51 Sqm 251.04 57,613.68 LGED 0.50) in/c cost of all materials complete as per =229.50 Sqm direction of the Engineer‐in‐Charge Cement concrete (1:2:4) with Portland cement, coarse sand (F.M 1.80), First class/ PJ brick chips (25mm to 5mm down‐ 3.00mX1.50mX0.0 5.03.05‐ graded)in the foundation of guide wall, cost 75m X51 Cum 6362.15 1,09,,508.58 LGED of materials and shuttering, mixing by =0.3375 SqmX51 concrete mixer machine, casting, laying, = 17.212Cum curing for the requisite period, etc. as per direction of the Engineer‐in Charge Brick work with 1st class bricks with 6mm thick cement mortar (1.4) for guide wall of R.C.C pipe filling the interstices tightly with 2.00mX2.50mX0.5 mortar, raking out joints, cleaning and 0m X 51 5.02.03‐ soaking bricks at least for 24 hours before = 2.50 CumX51 Cum 4665.16 5,94,806.63 LGED use, washing of sand, curing for requisite =127.50 Cubic period, cost of all materials, etc. all complete Meter as per direction of the Engineer‐in‐ Charge. (Minimum F.M. of sand: 12 mm thick cement plaster (1:4) in guide wall including cost of materials, washing of (2X1.00mX2.00m+ sand, curing for requisite period, maintaining 2X 0.25mX1.00m+ 5.12.01‐ proper curvatures of corners, side wall and 0.25m X2m)X51 Cum 172.0015 43,860.00 LGED bottom, costs of all materials, etc. complete, =5.00 CumX51 as per direction of the Engineer‐in‐charge. = 255.00 Cum (Minimum F.M. of sand: 1.2 Sub Total= 31,11,166.17 3.4 Construction of RCC Drain on the Slope of the Embankment 0.7 m X 0.675mX Earthwork in excavation of drains etc. by 11m X51 5.02.01‐ excavating earth to the lines, grades and =5,197X51 Cum 78.42 20,784.99 LGED elevation as per drawing, carrying and =265.07cubic disposing of all excavated materials; meter
Single brick flat soling with 1st class/ PJ bricks, true to level, camber, super elevation and 0.70m X 11X.51 5.03.01‐ grade in/c filling the joints with sand (FM =7.7 SqmX51 Sqm 251.04 98,583.41 LGED 0.50) in/c cost of all materials complete as per =392.70 Sqm direction of the Engineer‐in‐Charge Reinforced Cement Concrete in drain with Portland cement , sand (minimum F.M 1.80) 20mm down well graded crushed 1st class 0.2310 Cubic brick/picked brick chips (LAA value not meter RCC in per exceeding 40) including shuttering, mixing by running meter of . 4.2.04.02. concrete mixture machine casting , laying, drain X 11m X51 Cum 7270.00 9,42,126.57 LGED compacting, curing for 28 days, breaking Ist = 2.541X51 class/ picked brick chips etc complete in all =129.591 Cubic respect as per design drawing, design and meter drawing , and direction of Engineer in Charge” and cylinder crushing strength of concrete
Page 176 September 2013 Technical Designs for Tranch‐1 Work
should not be less than 170 kg/cm2 (suggested mix proportion 1:2:4) excluding reinforcement and fabrication, but including cost of all materials, reinforcement, and its fabrication shuttering, casting curing for 28 days and all incidental charges ,
Supplying and Fabrication of M.S High strength deformed bar/Twisted bar reinforcement of size and length for all types of RCC work including straightening the rod, removing ruts, cleaning, cutting, hooking, bending, binding, with supply of 22 B.W.G. GI wire, placing in position, including lapping, spacing and securing them in position by 119.57 kg of MS concrete blocks (1:1), metal chairs, etc. road in per running 6.051‐ complete including cost of all materials, labor, meter of R.C.C kg 67.63 45,36,537.22 LGED local handling, laboratory test, incidentals drain X11mX51 necessary to complete the work as per =1315.27kgX51 specifications, drawings and direction of the =67078..77 kg Engineer. Laboratory test for physical, strength, elongation % & bend to be performed as peer ASTM. (Measurement will be based on standard weight of 490 lbs. /ft3 Chairs, laps and separators will be measures for payment. The cost of these will be included in the unit rate). Cement concrete (1:2:4) in Spill way with Portland cement, coarse sand (F.M 1.80), First class/ PJ brick chips (25mm to 5mm 1.00mX1.00mX0.1 5.03.05‐ down‐ graded), cost of materials and 50m.X 51 Cum 6362.15 48,670,.45 LGED shuttering, mixing by concrete mixer =0.150CumX51 machine, casting, laying, curing for the = 7.65 Cum requisite period, etc. as per direction of the Engineer‐in Charge Sub Total= 56,46,702.63
Total= 22,93,07,128.90 Verakhola-Kaijuri Road Length: 13 Kilometer
Bill of Quantities Annexure-A Rate Item Code Amount Item Description Measurement Quantity Unit (in No (in Taka) Taka) Construction of Pavement 02/07/02‐ Preparation of Sub‐grade 13,000.00m x 5.50m Sqm 85.00 60,77,500.00 RHD (450mm depth) =71,500.00 Sqm
02/08/01‐ 13,000.00m x 5.50m x0.200m Improved Sub‐Grade Cum 804.00 1,14,97,200.00 RHD =14,300 .00 Cum 2 x13000.00m x1.50m 02/11/01‐ Construction of Hard Shoulders x0.200m Cum 4068.00 3,17,30,400.00 RHD = 7800.00 Cum 03/02/01‐ Sub ‐ base 13,000.00m x 5.50m x0.200m Cum 3953.00 5,65,27,900.00 RHD =14,300.00Cum
Page 177 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
03/03/02‐ Aggregate base 13,000.00m x 5.50m x0.200m RHD Cum 4275.00 6,11,32,500.00 = 14,300.00 Cum
03/06/01(b Bituminous Prime coat (Hand 13,000.00m x 5.50m ) ‐RHD Sqm 87.00 62,20,500.00 place) =71,500.00 Sqm
03/07/01(b Bituminous Tack coat 13,000.00m x 5.50m ) ‐RHD Sqm 22.00 15,73,000.00 (Labor intensive work) =71,500.00 Sqm
03/11/01(a Premixed Bituminous Carpeting 13,000.00m x 5.50m x0.040m 13191.0 Cum 3,77,26,260.00 ) ‐RHD 40mm thick (Av.) =2,860.00 Cum 0
03/12/02‐ 2mm compacted‐ premix 13,000.00m x 5.50m Sqm 126.00 90,09,000.00 RHD Bituminous Seal Coat. =71,500.00 Sqm
03/13/01‐ 2 x13,000.00m Brick on end edging Lin. M 88.00 22,88,000, 00 RHD =26,000.00 Lin. M Sub Total= 22,37,82,260.00 2. Protection of the Slope of the Embankment * 600mm thick blanket of earth cladding with 13,000.00mX12.0 specified cohesive soil on the side slope of 0 m Sqm 110.00 1,71,60,000.00 embankment =1,56,000.00 Sqm ** Supplying and planting vertiver (Binna) grass in 13,000.00mX12.0 bunch of 2 to 3 stem @ of 225 mm all over the 0 m Sqm 48.00 74,88,000.00 side slope =1,56,000.00 Sqm Sub Total= 2,46,48,000.00
3.Surface Drain and Cross Drain 3.1 Construction of 400 mmX550mm Surface Drain 1.15 X 0.7X Earthwork in excavation of drains etc. by 13000.00 5.02.01‐ excavating earth to the lines, grades and = 10,465.00 cubic Cum 78.42 8,20,,665.30 LGED elevation as per drawing, carrying and meter disposing of all excavated materials;
Single brick flat soling with 1st class/ PJ bricks, true to level, camber, super elevation and 5.03.01‐ 1.15X 13,000.00 grade in/c filling the joints with sand (FM Sqm 251.04 37,53,048.00 LGED =14,9500.00Sqm 0.50) in/c cost of all materials complete as per direction of the Engineer‐in‐Charge Brick work with 1st class bricks with 6mm thick cement mortar (1.4) for guard wall of (2X0.375mX0.25 drain, foot path and median, filling the mX1.m+2X interstices tightly with mortar, raking out 0.30mmX0.250m 5.02.03‐ joints, cleaning and soaking bricks at least for X 1m )X 13,000.00 Cum 4665.16 2,50,16,920.50 LGED 24 hours before use, washing of sand, curing =0.412513,000.00 for requisite period, cost lof al materials, etc. =5,362.50 Cubic all complete as per direction of the Engineer‐ Meter in‐ Charge. (Minimum F.M. of sand: Cement concrete (1:2:4) with Portland cement, coarse sand (F.M 1.80), First class/ 1.15X0.075X PJ brick chips (25mm to 5mm down‐ graded), 13,000.00 5.03.05‐ cost of materials and shuttering, mixing by =0.08625X13000. Cum 6362.15 71,33,560.69 LGED concrete mixer machine, casting, laying, 00 curing for the requisite period, etc. as per = 1121.25 Cum direction of the Engineer‐in Charge 12 mm thick cement plaster (1:4) in drain (0.300m+0.250m including cost of materials, washing of sand, +0.550m+0.600m 5.12.01‐ curing for requisite period, maintaining +0.250m+0.850m Sqm 172.00 6,26,080.00 LGED proper curvatures of corners, side wall and )X13,000.00 bottom, costs of all materials, etc. complete, =0.280m X as per direction of the Engineer‐in‐charge. 13,000.00
Page 178 September 2013 Technical Designs for Tranch‐1 Work
(Minimum F.M. of sand: 1.2 = 3,640.00Sqm
Sub Total= 3,73,50,274.49 3.2 Construction of 750mmX750mm X 750mm Storm Water Catch Pit at 200.00 Meter Apart 1.050m X 1.050mX 0.975m Earthwork in excavation of drains etc. by X 66 5.02.01‐ excavating earth to the lines, grades and =1.0749X66 Cum 78.42 5,563.58 LGED elevation as per drawing, carrying and =70.946 Cubic disposing of all excavated materials; meter
Single brick flat soling with 1st class/ PJ bricks, 1.050m X true to level, camber, super elevation and 5.03.01‐ 1.050mX 66 grade in/c filling the joints with sand (FM Sqm 251.04 18,266.93 LGED =1.1025 SqmX66 0.50) in/c cost of all materials complete as per =72.765 Sqm direction of the Engineer‐in‐Charge Reinforced Cement Concrete in drain work Portland cement , sand (minimum F.M 1.80) 20mm down well graded crushed 1st class brick/picked brick chips (LAA value not exceeding 40) including shuttering, mixing by concrete mixture machine casting , laying, 0.325 Cubic compacting, curing for 28 days, breaking Ist meter RCC in class/ picked brick chips etc complete in all 4.1.10.02.2 each catch pit X respect as per design drawing, design and Cum 7270.00 1,55,701.59 LGED 66 drawing , and direction of Engineer in Charge” = 21.42 Cubic and cylinder crushing strength of concrete meter should not be less than 170 kg/cm2 (suggested mix proportion 1:2:4) excluding reinforcement and fabrication, but including cost of all materials, reinforcement, and its fabrication shuttering, casting curing for 28 days and all incidental charges , 6.051‐LGED Supplying and Fabrication of M.S high strength deformed bar/Twisted bar reinforcement of size and length for all types of RCC work including straightening the rod, removing ruts, cleaning, cutting, hooking, bending, binding, with supply of 22 B.W.G. GI wire, placing in position, including lapping, spacing and securing them in position by concrete blocks (1:1), metal chairs, etc. 167.97kg of MS complete including cost of all materials, labor, road in each kg 67.63 7,49,,747.53 local handling, laboratory test, incidentals catch pit X66 necessary to complete the work as per =11,086.02 kg specifications, drawings and direction of the Engineer. Laboratory test for physical, strength, elongation % & bend to be performed as peer ASTM. (Measurement will be based on standard weight of 490 lbs./ft3 Chairs, laps and separators will be measures for payment. The cost of these will be included in the unit rate). Sub Total= 9,29,279.62
3.3 Supplying and Fitting and Fixing of 500.mm R.C.C Pipe at 200 meter Apart along the Alignment of the Drain
Page 179 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
Supplying precast RCC pipes(500 mm internal dia,50mm thick) with 12mm downgraded dust free 1st class brick chips (1:2:4)including 12 meter long pipe joint gap filling in neat cement slurry 6.096‐LGED RCC pipeX66 meter 2910.83 23,05,377.36 casting, curing, laying in position, from =792.00 meter finished type by steel form works as per design , specifications complete as per direction of Engineere‐in Charg
Single brick flat soling with 1st class/ PJ bricks, 3.00 m X true to level, camber, super elevation and 5.03.01‐ 1.50mX.6 grade in/c filling the joints with sand (FM Sqm 251.04 74,558.88 LGED =4.5 SqmX66 0.50) in/c cost of all materials complete as per =297.00 Sqm direction of the Engineer‐in‐Charge
Cement concrete (1:2:4) with Portland cement, coarse sand (F.M 1.80), First class/ PJ brick chips (25mm to 5mm down‐ 3.00mX1.50mX0. 5.03.05‐ graded)in the foundation of guide wall, cost 075m X66 Cum 6362.15 1,41,716.8 LGED of materials and shuttering, mixing by =0.3375 SqmX66 concrete mixer machine, casting, laying, = 22.275.5Cum curing for the requisite period, etc. as per direction of the Engineer‐in Charge Brick work with 1st class bricks with 6mm thick cement mortar (1.4) for guide wall of R.C.C pipe filling the interstices tightly with 2.00mX2.50mX0. mortar, raking out joints, cleaning and 50m X 66 5.02.03‐ soaking bricks at least for 24 hours before = 2.50 CumX66 Cum 4665.16 7,69,749.75 LGED use, washing of sand, curing for requisite =165.00 Cubic period, cost of all materials, etc. all complete Meter as per direction of the Engineer‐in‐ Charge. (Minimum F.M. of sand: 12 mm thick cement plaster (1:4) in guide (2X1.00mX2.00m wall including cost of materials, washing of + 2X sand, curing for requisite period, maintaining 5.12.01‐ 0.25mX1.00m+ proper curvatures of corners, side wall and Cum 172.0015 56,760.00 LGED 0.25m X2m)X66 bottom, costs of all materials, etc. complete, =5.00 Cum as per direction of the Engineer‐in‐charge. = 330.00 Cum (Minimum F.M. of sand: 1.2 Sub Total= 33,48,162.88 3.4 Construction of RCC Drain on the Slope of the Embankment 0.7 m X 0.675mX Earthwork in excavation of drains etc. by 11m X66 5.02.01‐ excavating earth to the lines, grades and =5,197X66 Cum 78.42 26,898.22 LGED elevation as per drawing, carrying and =343.02cubic disposing of all excavated materials; meter
Single brick flat soling with 1st class/ PJ bricks, true to level, camber, super elevation and 0.70m X 11X.66 5.03.01‐ grade in/c filling the joints with sand (FM =7.7 SqmX66 Sqm 251.04 1,27,578.53 LGED 0.50) in/c cost of all materials complete as per =508.20 Sqm direction of the Engineer‐in‐Charge Reinforced Cement Concrete in drain with Portland cement , sand (minimum F.M 1.80) 20mm down well graded crushed 1st class 0.2310 Cubic brick/picked brick chips (LAA value not meter RCC in per exceeding 40) including shuttering, mixing by running meter of . 4.2.04.02. concrete mixture machine casting , laying, drain X 11m X66 Cum 7270.00 12,19,222.62 LGED compacting, curing for 28 days, breaking Ist = 2.541X66 class/ picked brick chips etc complete in all =167.706 Cubic respect as per design drawing, design and meter drawing , and direction of Engineer in Charge” and cylinder crushing strength of concrete
Page 180 September 2013 Technical Designs for Tranch‐1 Work
should not be less than 170 kg/cm2 (suggested mix proportion 1:2:4) excluding reinforcement and fabrication, but including cost of all materials, reinforcement, and its fabrication shuttering, casting curing for 28 days and all incidental charges ,
Supplying and Fabrication of M.S High strength deformed bar/Twisted bar reinforcement of size and length for all types of RCC work including straightening the rod, removing ruts, cleaning, cutting, hooking, bending, binding, with supply of 22 B.W.G. GI wire, placing in position, including lapping, 119.57 kg of MS spacing and securing them in position by road in per concrete blocks (1:1), metal chairs, etc. running meter of complete including cost of all materials, labor, 6.051‐LGED R.C.C drain kg 67.63 58,70,812.87 local handling, laboratory test, incidentals X11mX66 necessary to complete the work as per =1315.27kgX66 specifications, drawings and direction of the =86807.82 kg Engineer. Laboratory test for physical, strength, elongation % & bend to be performed as peer ASTM. (Measurement will be based on standard weight of 490 lbs. /ft3 Chairs, laps and separators will be measures for payment. The cost of these will be included in the unit rate). Cement concrete (1:2:4) in Spill way with Portland cement, coarse sand (F.M 1.80), First class/ PJ brick chips (25mm to 5mm 1.00mX1.00mX0. 5.03.05‐ down‐ graded), cost of materials and 150m.X 66 Cum 6362.15 62,985.29 LGED shuttering, mixing by concrete mixer =0.150CumX66 machine, casting, laying, curing for the = 9.90 Cum requisite period, etc. as per direction of the Engineer‐in Charge Sub Total= 73,07,497.52
Total= 29,73,65,474.51
Page 181 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
Figure-1: Section and Plan of Drain
Section of 400 mmX550 mm Drain
250mm
300mm 250mm
300mm 400mm 300mm 550mm 700mm 700mm
375mm 375mm 250mm 75mm 75mm
1150mm
Figure‐2: 400mmX400mmX500mm RCC Drain of the Side Slope of Plan of 400mmX550mmEmbankment Drain
Section of 450mmX400mmX400mm RCC Drain
125mm 250mm 400mm 250mm 125mm 1000.00mm 150mm 700mm 150mm 400mm
1150mm
mm 675
Page 182 September 2013 Technical Designs for Tranch‐1 Work
Plan of 700mmX400mmX400mm RCC Drain
700mm
150mm 400mm
150mm
700mm 400mm
Quantity of R.C.C and Reinforcement in R.C.C Drain of the Embankment Slope SL Description Item Measurement Quantity 0.2310 Cum Reinforce Cement 2X525mX150mm+700mmX700mmX150mm 1 = 8.134 cubic Concrete(RCC) = 0. 2310Cum; 0.2310 X35.218= 7.87Cubic feet feet 2. Amount of Reinforcement and Fabrication considering 8.134Cubic feet X0.03X490=119.57 kg 119.57 kg 3% of 19.792 Cum of R.C.C
Figure-3: Section and Plan of 750 mmX750mmX750mm RCC Storm Water Catch Pit
Section of 750 mmX750mmX750mm RCC Storm Water Catch Pit
150mm 1050mm 150mm
750mm
600.00mm Diameter 75mm thick R.C.C Pipe
750 mm 750
mm 975
Page 183 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
Plan of 1000mmX900mmX900mm RCC Storm Water Catch Pit
1050mm 750mm 150mm
150mm
1050 mm 1050 750 mm 750
Quantity of R.C.C and Reinforcement in Each Storm Water Catch PIT SL Description Item Measurement Quantity 2X750mmX150mm+1050mmX1050mmX150mm ‐ Reinforce Cement 3.14X(375mm)2X150mm 0.3245 Cum 1 Concrete(RCC) =0.390.75 ‐0.06624= 0.3245 Cum; 0.3245X35.218= 11.427 = 11.427 cubic feet Cubic feet 2. Amount of Reinforcement and Fabrication considering 11.427 Cubic feet X0.03X490=167.97kg 167.97 kg 3% of 19.792 Cum of R.C.C
Figure-4: Pavement Details
SHOULDER CARRIAGEWAY SHOULDER 1.5 5.5 1.5 3% 3% 5% 5%
SURFACING (SEAL COAT (0.12M)+ BITUMINOUS CARPEIING (0.40M) BASE 0.200 M BRICK ON END EDGING SUB-BASE 0.200 M IMPROVED SUB-GRADE 0.200 M
Page 184 September 2013 Technical Designs for Tranch‐1 Work
Figure-5: Lay out Plan of R.C. C Pipe, Embankment Slope Drain and Spill Way
600mm Cladding Layer 2000mmX2500mmX500mm Guide Wall 2000m
700mmX400mmX400mm RCC Drain 12 meter X600mm diameter, X50mm thick R.C. Pipe 1000mm
700mmX400mmX400mm RCC Drain 2500mm 3000mmX1500mm Embedded in Cladding Layer Cement Concrete (C.C) 1500mm
3000m
1000mmX1000mmX75mm CC Spill way
Page 185 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
Main River Flood Embankment and Erosion Risk Management Program Road on the Land‐Side of Rehabilitated or Reconstructed Embankment
BOQ of the Proposed Road cum Flood Embankment cum Road (As per Specification & Unit Rate of LGED)
Main River Flood and Bank Erosion Risk Management Program include construction of two roads r under tranche-1 as shown in Table-1:
Table‐1: Roads under Trenche‐1 Serial Start point End point Length Location
1 Verakhola Kaijuri 13.00 KM Land‐side Bank of Jamuna River 2 Verakhola Baghabari 10.00 KM Land‐side Bank Hurasagar River
The proposed roads would have 5.5 meter bituminous pavement with 1.5 meter hard shoulder in each side. The road would be designed to function not only as part of flood embankment and shelter for flood effected population but would also provide connectivity to growth centers, river ports, local government institutions situated ein th adjoining area of the proposed flood embankments of Pabna, Sirajganj districts. It is obvious that the both roads would be connected to the nearby national highways to meet the growing demand of the traffic in future and to facilitate better connectivity of population
The roads may be designed as Upazila road of Type design ‐4 of LGED as road classification system of LGED approved by The Planning Commission of Bangladesh which define ownership and responsibilities of the road system of the country. According to the classification LGED will be responsible for construction, development and maintenance of three classes of roads, which has been named as Upazila Road, Union Road and Village Road in collaboration with Local Government Institution (LGI). Road type with definition and the ownership and responsibility are furnished in Table 2. below:
Table‐2: Road Network Classification with Definition
Serial Type Definition Ownership and Number Responsibility
1. National Highways connecting National capital with Divisional HQs or sea ports or RHD Highway land ports or Asian Highway 2. Regional Highways connecting District HQs or main river or land ports or with each RHD Highway other not connected by national Highways. 3. Zilla Road Roads connecting District HQ/s with Upazila HQ/s or connecting one RHD Upazila HQ to another Upazila HQ by a single main connection with National /Regional Highway, through shortest distance/ route. 4. Upazila Roads connecting Upazila HQ/s with Growth Center/s or one Growth LGED/LGI** Road Center with another Growth Center by a single main connection or (UZR) connecting Growth Center to Higher Road System,* through shortest distance/route. (Former Feeder Road Type‐B) 5. Union Road Roads connecting union HQ/s with Upazila HQs, Growth Centers or local LGED/LGI (UNR) markets or with each other. (Former Rural Road Class‐1 (R1) 6. Village Road a) Roads connecting Villages with Union HQs, local markets, farms and LGED/LGI (VR) ghats or with each other. (Former Rural Road Class‐2 (R2)
b) Roads within a Village. (Former Rural Road Class‐3 (R3)
Page 186 September 2013 Technical Designs for Tranch‐1 Work
* Higher Road System‐ National Highway, Regional Highway, and Zila Roads; ** LGI‐ Local Government Institutions;. The design standards relate the width of the road (geometric design) and thickness of various layers (pavement) to the classification of the road. It has been recommended that there should be 6 basic geometric design stype for Zilla, Upazila and Union Roads all based on traffic criteria. Design types 5 ‐ 8 have been based primarily on forecasts/ survey of commercial vehicles (applicable for LGED). Design types 3 and 4 are based primarily on forecasts of peak hour passenger car units (pcu’s). The approved geometric design for each type of road is summarized in Table 3
Table 3: Approved Geometric Design Standards
Road Class Design Type Carriageway (m)/(ft) Hard Shoulder Verge Crest Width (m)/(ft) (m)/(ft) (m)/(ft)
Union Road 8 3.0/10 0/0 1.25/4 5.5/18 7 3.7/12 0/0 0.90/3 5.5/18 Upazila Road 6 3.7/12 0/0 1.8/6 7.3/24
5 3.7/12 0.9/3 0.9/3 7.3/24 4 5.5/18 0/0 2.15/7 9.8/32 Zila Road 5 3.7/12 0.9/3 0.9/3 7.3/24
4 5.5/18 0/0 2.15/7 9.8/32 3 5.5/18 1.2/4 0.95/3 9.8/32
For Types 8, 7, 6 and 5 the criterion should be daily commercial vehicles. For Types 4 and 3 the criterion should be peak hour pcu’s. Traffic criteria for each design type are shown in Table 4 below:
Table: 4 Traffic Criteria for Design Purposes Design Type Daily Commercial Vehicles (CVD)
8 Up to 50 7 51‐100 6 101‐200 5 201‐300 4 301‐600
It been mentioned in Road Design Standards, Standard Designs and Costing for Zilla, Upazila and Union Roads, Bridges and Culverts of LGED that Design type‐4 of Upazila roads of LGED is suitable traffic of 4300 ‐ 600 commercial vehicle per day or traffic of 290‐530 pcu.. The widened (18ft) carriageway allows a better distribution on the pavement for this high level of traffic, increasing the design life of the pavement.
Page 187 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
Table-5: Pavement of Different Layers of Type Design-4 of Upazila Road of LGED
The feasibility level design of the pavement and geometric elements of the road have been proposed as per standards and specifications of Upazila Road of LGED‐Type‐4. The cross‐section of pavement of the proposed road showing the thickness of different layer of pavement components is given in figure‐1. U‐shaped surface drain of 350.00mm wide along with storm water catch pit of 900.00 X900.00mmX1000.00 at 200.00mm apart have proposed to drain off storm/rain water from road surface. In addition, 500.00.mm diameter RCC pipe has been proposed to provide cross‐ wise underneath the pavement for each catch pit to drain off the water to the outer side of the road crest. The cross‐section of the road side drain, storm water catch pit, Cross drain, have been shown in Figure‐ 2, Figure‐3, Figure‐4 and Figure‐5.
Bill of Quantities for the Construction of Proposed Roads The standards and speculations and the rate schedule of regional roads of RHD have been primarily used in preparation of Bill of Quantities (BOQ) items of pavement works. In case of R.C.C and Brick works, standards and speculations of and schedule of rates of LGED have been used. The BOQ cost of Verakhola ‐ Kaijuri road and Verakhola – Baghabari road are TK. 28, 33, 75,736.50 and TK. 21, 60, 72,756.90 respectively. BOQ cost of two roads is TK. 49, 94, 48,493.40. The BOQ of Verakhola ‐ Kaijuri road and Verakhola – Baghabari road are annexed as Annexure‐A and Annexure‐B
Verakhola‐ Verakhola‐Kaijuri Baghabari Road Total SL Description of Items Road (in Taka) (in Taka) (3+ ‐4)
1 2 3 4 5
1 Construction of Pavement 20,97,92,522.00 15, 89,05,900.00 36,86,98,422.00
2 Protection of the Slope of the Embankment 2,46,48,000.00 1,89,60,000.00 4,36,08,000.00
3 Surface Drain and Cross Drain 3.1 Construction of 400 mmX550mm Surface Drain 3,73,50,274.49 2,87,30,908.38 6,60,81,182.87
Construction of 750mmX750mm X 750mm Storm 3.2 9,29,279.62 7,18,079.72 16,47,359.33 Water Catch Pit at 200.00 Meter Apart 3.3 Supplying and Fitting and Fixing of 500.mm R.C.C 33,48,162.88 31,11,166.17 64,59,329.05
Page 188 September 2013 Technical Designs for Tranch‐1 Work
Pipe at 200 meter Apart along the Alignment of the Drain Construction of RCC Drain on the Slope of the 3.4 73,07,497.52 56,46,702.63 1,29,54,200.15 Embankment
Total Cost of Two Roads 28,33,75,736.50 21,60,72,756.90 49,94,48,493.40
Based on Specification and Rate Schedule of LGED Verakhola‐ Verakhola‐Kaijuri Total SL Description of Items Baghabari Road (in Road (in Taka) (3+ ‐4) Taka) 1 2 3 4 5
1 Construction of Pavement 20,97,92,522.00 15, 89,05,900.00 36,86,98,422.00
2 Protection of the Slope of the Embankment 2,46,48,000.00 1,89,60,000.00 4,36,08,000.00
3 Surface Drain and Cross Drain
3.1 Construction of 400 mmX550mm Surface Drain 3,73,50,274.49 2,87,30,908.38 6,60,81,182.87
Construction of 750mmX750mm X 750mm Storm 3.2 9,29,279.62 7,18,079.72 16,47,359.33 Water Catch Pit at 200.00 Meter Apart Supplying and Fitting and Fixing of 500.mm R.C.C 3.3 Pipe at 200 meter Apart along the Alignment of 33,48,162.88 31,11,166.17 64,59,329.05 the Drain Construction of RCC Drain on the Slope of the 3.4 73,07,497.52 56,46,702.63 1,29,54,200.15 Embankment
Total Cost of Two Roads 28,33,75,736.50 21,60,72,756.90 49,94,48,493.40
Based on Specification and Rate Schedule of RHD Verakhola‐ Verakhola‐Kaijuri Baghabari Road (in Total SL Description of Items Road (in Taka) Taka) (3+ ‐4)
1 2 3 4 5
1 Construction of Pavement 22,37,82,260.00 17,21,40,200.00 39,59,22,460.00
2 Protection of the Slope of the Embankment 2,46,48,000.00 1,89,60,000.00 4,36,08,000.00
3 Surface Drain and Cross Drain 3. Construction of 400 mmX550mm Surface Drain 3,73,50,274.49 2,87,30,908.38 6,60,81,254.87 1 3. Construction of 750mmX750mm X 750mm Storm 9,29,279.62 7,18,079.72 16,47,359.33 2 Water Catch Pit at 200.00 Meter Apart Supplying and Fitting and Fixing of 500.mm R.C.C 3. Pipe at 200 meter Apart along the Alignment of 33,48,162.88 31,11,166.17 64,59,329.05 3 the Drain 3. Construction of RCC Drain on the Slope of the 73,07,497.52 56,46,702.63 1,29,54,200.15 4 Embankment
Total Cost of Two Roads 29,73,65,474.51 22,93,07,128.89 52,66,72,603.40
Page 189 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
Verakhola‐Baghabari Road Length: 10 Kilometer Bill of Quantities Annexure‐B Rate Amount Item Code No Item Description Measurement Quantity Unit (in (in Taka) Taka) Construction of Pavement 3.1.08 of Schedule of Rate, Preparation of Sub‐ 10000.00m x 5.50m Pabna and, Serajganj districts grade (450mm Sqm 74.08 40,74,400.00 =55,000.00 Sqm of LGED, July’2012 depth) 3.1.086 of Schedule of Rate, 10000.00m x 5.50m Improved Sub‐ Pabna and, Serajganj districts x0.200m Cum 558.98 88,44,000.00 Grade of LGED, July’2012 =11,000 .00 Cum 3.2.02.01 of Schedule of Rate, 10000.00m x 5.50m Sub ‐ base Pabna and, Serajganj districts x0.200m Cum 2887.84 3,17,66,240.00
of LGED, July’2012 =11,000.00Cum 3.2.03.02 of Schedule of Rate, 10000.00m x 5.50m Aggregate base Pabna and, Serajganj districts x0.200m Cum 4717.36 5,18,90,960.00
of LGED, July’2012 = 11,000.00 Cum 3.2.25.01 of Schedule of Rate, Bituminous Prime 10000.00m x 5.50m Pabna and, Serajganj districts Sqm 112.04 61,62,200.00 coat (Hand place) =55,000.00 Sqm of LGED, July’2012 Bituminous Tack 3.2.24.05 of Schedule of Rate, coat 10000.00m x 5.50m Pabna and, Serajganj districts Sqm 52.45 28,84,750.00 (Labor intensive =55,000.00 Sqm of LGED, July’2012 work) Premixed 3.2.30.2 of Schedule of Rate, Bituminous 10000.00m x 5.50m Pabna and, Serajganj districts Sqm 702.10 3,86,15,500.00 Carpeting 40mm =55,000.00 Sqm of LGED, July’2012 thick (Av.) 3.1.08 of Schedule of Rate, 2mm compacted‐ 10000.00m x 5.50m Pabna and, Serajganj districts premix Bituminous Sqm 228.91 1,25,90,050.00 =55,000.00 Sqm of LGED, July’2012 Seal Coat. 3.2.15.01 of Schedule of Rate, 2 x 10000.00m Lin. Pabna and, Serajganj districts Brick on end edging 73.89 14,77,800.00 =20,000.00 Lin. M M of LGED, July’2012 15,89,05,900.0 Sub Total= 0 2.Protection Work of the Slope of the Embankment * 600mm thick blanket of earth cladding with 10,000.00mX12.00 m specified cohesive soil on the side slope of Sqm 110.00 1,32,00,000.00 =1,20,000.00 Sqm embankment ** Supplying and planting vertiver (Binna) grass in 10,000.00mX12.00 m bunch of 2 to 3 stem @ of 225 mm all over the Sqm 48.00 57,60,000.00 =1,20,000.00 Sqm side slope Sub Total= 1,89,60,000.00
3.Surface Drain and Cross Drain 3.1 Construction of 400 mmX550mm Surface Drain 1.15 X 0.7X 10,000.00 Earthwork in excavation of drains etc. by = 0.8050X10,000 5.02.01 excavating earth to the lines, grades and = 8,050.00 cubic Cum 78.42 6,31,281.00 ‐LGED elevation as per drawing, carrying and disposing meter of all excavated materials;
Single brick flat soling with 1st class/ PJ bricks, true to level, camber, super elevation and grade 5.03.01 1.15mX 10,000.00 in/c filling the joints with sand (FM 0.50) in/c cost Sqm 251.04 28,86,960.00 ‐LGED =11,500.00 Sqm of all materials complete as per direction of the Engineer‐in‐Charge
Page 190 September 2013 Technical Designs for Tranch‐1 Work
Brick work with 1st class bricks with 6mm thick cement mortar (1.4) for guard wall of drain, foot (2X0.375mX0.25mX1. path and median, filling the interstices tightly m+2X with mortar, raking out joints, cleaning and 0.30mmX0.250mX 5.02.03 soaking bricks at least for 24 hours before use, 1m )X 10,000.00 Cum 4665.16 1,92,43,785.50 ‐LGED washing of sand, curing for requisite period, cost =0.4125X10,000.00 of all materials, etc. all complete as per direction =4,125.00 Cubic of the Engineer‐in‐ Charge. (Minimum F.M. of Meter sand: Cement concrete (1:2:4) with Portland cement, coarse sand (F.M 1.80), First class/ PJ brick chips 1.15mX075mX (25mm to 5mm down‐ graded), cost of materials 5.03.05 10,000.00 and shuttering, mixing by concrete mixer Cum 6362.15 54,87,354.38 ‐LGED =0.08625X10,000.00 machine, casting, laying, curing for the requisite = 862.50 Cum period, etc. as per direction of the Engineer‐in Charge 12 mm thick cement plaster (1:4) in drain (0.300m+0.250m+0.5 including cost of materials, washing of sand, 50m+0.600m+0.250 curing for requisite period, maintaining proper 5.12.01 m+0.850m)X10,000.0 curvatures of corners, side wall and bottom, costs Sqm 172.00 4,81,600.00 ‐LGED 0 of all materials, etc. complete, as per direction of =0.280m X 10,000.00 the Engineer‐in‐charge. (Minimum F.M. of sand: = 2,800.00Sqm 1.2
Sub Total= 2,87,30,908.38 3.2 Construction of 750mmX750mm X 750mm Storm Water Catch Pit at 200.00 Meter Apart 1.050m X 1.050mX Earthwork in excavation of drains etc. by 0.975m X 51 5.02.01 excavating earth to the lines, grades and =1.0749X51 Cum 78.42 4,299.13 ‐LGED elevation as per drawing, carrying and disposing =54.82 Cubic meter of all excavated materials;
Single brick flat soling with 1st class/ PJ bricks, 1.050m X 1.050mX true to level, camber, super elevation and grade 5.03.01 51 in/c filling the joints with sand (FM 0.50) in/c cost Sqm 251.04 14,115.35 ‐LGED =1.1025 SqmX51 of all materials complete as per direction of the =56.227 Sqm Engineer‐in‐Charge Reinforced Cement Concrete in drain work Portland cement , sand (minimum F.M 1.80) 20mm down well graded crushed 1st class brick/picked brick chips (LAA value not exceeding 40) including shuttering, mixing by concrete mixture machine casting , laying, compacting, curing for 28 days, breaking Ist class/ picked brick 0.325 Cubic meter 4.1.10. chips etc complete in all respect as per design RCC in each catch pit 02.2 Cum 7,270.00 1,20,314.87 drawing, design and drawing , and direction of X 51 LGED Engineer in Charge” and cylinder crushing = 16.55 Cubic meter strength of concrete should not be less than 170 kg/cm2 (suggested mix proportion 1:2:4) excluding reinforcement and fabrication, but including cost of all materials, reinforcement, and its fabrication shuttering, casting curing for 28 days and all incidental charges ,
Page 191 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
6.051‐ Supplying and Fabrication of M.S high strength LGED deformed bar/Twisted bar reinforcement of size and length for all types of RCC work including straightening the rod, removing ruts, cleaning, cutting, hooking, bending, binding, with supply of 22 B.W.G. GI wire, placing in position, including lapping, spacing and securing them in position by concrete blocks (1:1), metal chairs, etc. complete 167.97kg of MS road including cost of all materials, labor, local in each catch pit X51 kg 67.63 5,79,,350.37 handling, laboratory test, incidentals necessary to =8,566.47 kg complete the work as per specifications, drawings and direction of the Engineer. Laboratory test for physical, strength, elongation % & bend to be performed as peer ASTM. (Measurement will be based on standard weight of 490 lbs./ft3 Chairs, laps and separators will be measures for payment. The cost of these will be included in the unit rate). Sub Total= 7,18,079.72 3.3 Supplying and Fitting and Fixing of 500.mm R.C.C Pipe at 200 meter Apart along the Alignment of the Drain Supplying precast RCC pipes(500 mm internal dia,50mm thick) with 12mm downgraded dust free 1st class brick chips (1:2:4)including pipe 12 meter long RCC 6.096‐ mete joint gap filling in neat cement slurry casting, pipeX51 =792.00 2910.83 23,05,377.36 LGED r curing, laying in position, from finished type by meter steel form works as per design , specifications complete as per direction of Engineere‐in Charg
Single brick flat soling with 1st class/ PJ bricks, true to level, camber, super elevation and grade 3.00 m X 1.50mX.6 5.03.01 in/c filling the joints with sand (FM 0.50) in/c cost =4.5 SqmX51 Sqm 251.04 57,613.68 ‐LGED of all materials complete as per direction of the =229.50 Sqm Engineer‐in‐Charge
Cement concrete (1:2:4) with Portland cement, coarse sand (F.M 1.80), First class/ PJ brick chips 3.00mX1.50mX0.075 (25mm to 5mm down‐ graded)in the foundation 5.03.05 m X51 of guide wall, cost of materials and shuttering, Cum 6362.15 1,09,,508.58 ‐LGED =0.3375 SqmX51 mixing by concrete mixer machine, casting, = 17.212Cum laying, curing for the requisite period, etc. as per direction of the Engineer‐in Charge Brick work with 1st class bricks with 6mm thick cement mortar (1.4) for guide wall of R.C.C pipe filling the interstices tightly with mortar, raking 2.00mX2.50mX0.50m 5.02.03 out joints, cleaning and soaking bricks at least for X 51 Cum 4665.16 5,94,806.63 ‐LGED 24 hours before use, washing of sand, curing for = 2.50 CumX51 requisite period, cost of all materials,. etc all =127.50 Cubic Meter complete as per direction of the Engineer‐in‐ Charge. (Minimum F.M. of sand: 12 mm thick cement plaster (1:4) in guide wall including cost of materials, washing of sand, (2X1.00mX2.00m+ 2X curing for requisite period, maintaining proper 0.25mX1.00m+ 5.12.01 172.001 curvatures of corners, side wall and bottom, costs 0.25m X2m)X51 Cum 43,860.00 ‐LGED 5 of all materials, etc. complete, as per direction of =5.00 CumX51 the Engineer‐in‐charge. (Minimum F.M. of sand: = 255.00 Cum 1.2 Sub Total= 31,11,166.17 3.4 Construction of RCC Drain on the Slope of the Embankment 0.7 m X 0.675mX 11m Earthwork in excavation of drains etc. by X51 5.02.01 excavating earth to the lines, grades and =5,197X51 Cum 78.42 20,784.99 ‐LGED elevation as per drawing, carrying and disposing =265.07cubic meter of all excavated materials;
Page 192 September 2013 Technical Designs for Tranch‐1 Work
Single brick flat soling with 1st class/ PJ bricks, true to level, camber, super elevation and grade 0.70m X 11X.51 5.03.01 in/c filling the joints with sand (FM 0.50) in/c cost =7.7 SqmX51 Sqm 251.04 98,583.41 ‐LGED of all materials complete as per direction of the =392.70 Sqm Engineer‐in‐Charge Reinforced Cement Concrete in drain with Portland cement , sand (minimum F.M 1.80) 20mm down well graded crushed 1st class brick/picked brick chips (LAA value not exceeding 40) including shuttering, mixing by concrete 0.2310 Cubic meter mixture machine casting , laying, compacting, RCC in per running curing for 28 days, breaking Ist class/ picked brick . 4.2.04. meter of drainm X 11 chips etc complete in all respect as per design 02. X51 Cum 9,42,126.57 drawing, design and drawing , and direction of 7270.00 LGED = 2.541X51 Engineer in Charge” and cylinder crushing =129.591 Cubic strength of concrete should not be less than 170 meter kg/cm2 (suggested mix proportion 1:2:4) excluding reinforcement and fabrication, but including cost of all materials, reinforcement, and its fabrication shuttering, casting curing for 28 days and all incidental charges , Supplying and Fabrication of M.S High strength deformed bar/Twisted bar reinforcement of size and length for all types of RCC work including straightening the rod, removing ruts, cleaning, cutting, hooking, bending, binding, with supply of 22 B.W.G. GI wire, placing in position, including lapping, spacing and securing them in position by 119.57 kg of MS road concrete blocks (1:1), metal chairs, etc. complete in per running meter 6.051‐ including cost of all materials, labor, local of R.C.C drain kg 67.63 45,36,537.22 LGED handling, laboratory test, incidentals necessary to X11mX51 complete the work as per specifications, drawings =1315.27kgX51 and direction of the Engineer. Laboratory test for =67078..77 kg physical, strength, elongation % & bend to be performed as peer ASTM. (Measurement will be based on standard weight of 490 lbs. /ft3 Chairs, laps and separators will be measures for payment. The cost of these will be included in the unit rate). Cement concrete (1:2:4) in Spill way with Portland cement, coarse sand (F.M 1.80), First 1.00mX1.00mX0.150 class/ PJ brick chips (25mm to 5mm down‐ 5.03.05 m.X 51 graded), cost of materials and shuttering, mixing Cum 6362.15 48,670,.45 ‐LGED =0.150CumX51 by concrete mixer machine, casting, laying, curing = 7.65 Cum for the requisite period, etc. as per direction of the Engineer‐in Charge
Sub Total= 56,46,702.63 Total= 21,60,72,756.80
Verakhola‐Kaijuri Road Length: 13 Kilometer Bill of Quantities Annexure‐A Rate Amount Item Code No Item Description Measurement Quantity Unit (in (in Taka) Taka) Construction of Pavement
3.1.08 of Schedule of Rate, Preparation of Sub‐ 13,000.00m x 5.50m Pabna and, Serajganj grade (300mm Sqm 74.08 52,96,420.00 =71,500.00 Sqm districts of LGED, July’2012 depth)
Page 193 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
3.1.086 of Schedule of Rate, 13,000.00m x 5.50m Pabna and, Serajganj Improved Sub‐Grade x0.200m Cum 558.98 1,14,97,200.00 districts of LGED, July’2012 =14,300 .00 Cum
3.2.02.01 of Schedule of 13,000.00m x 5.50m Sub ‐ base Rate, Pabna and, Serajganj x0.200m Cum 2887.84 4,,12,90,964.00
districts of LGED, July’2012 =14,300.00Cum
3.2.03.02 of Schedule of 13,000.00m x 5.50m Aggregate base Rate, Pabna and, Serajganj x0.200m Cum 4717.36 6,74,58,248.00
districts of LGED, July’2012 = 14,300.00 Cum 3.2.25.01 of Schedule of Bituminous Prime 13,000.00m x 5.50m Rate, Pabna and, Serajganj Sqm 112.04 80,10,860.00 coat (Hand place) =71,500.00 Sqm districts of LGED, July’2012
3.2.24.05 of Schedule of Bituminous Tack coat 13,000.00m x 5.50m Rate, Pabna and, Serajganj (Labor intensive Sqm 52.45 37,50,175.00 =71,500.00 Sqm districts of LGED, July’2012 work)
3.2.30.2 of Schedule of Rate, Premixed Bituminous 13,000.00m x 5.50m Pabna and, Serajganj Carpeting 40mm Sqm 702.10 5,02,00,150.00 =71,000.00 Sqm districts of LGED, July’2012 thick (Av.) 3.1.08 of Schedule of Rate, 12mm compacted‐ 13,000.00m x 5.50m Pabna and, Serajganj premix Bituminous Sqm 228.91 =71,500.00 Sqm 1,63,67,065.00 districts of LGED, July’2012 Seal Coat. 3.2.15.01 of Schedule of 2 x13,000.00m Lin. Rate, Pabna and, Serajganj Brick on end edging 73.89 19,21,140.00 =26,000.00 Lin. M M districts of LGED, July’2012 20,97,92,522.0 Sub Total= 0
* 600mm thick blanket of earth cladding with 13,000.00mX12.00 m specified cohesive soil on the side slope of Sqm 110.00 1,71,60,000.00 =1,56,000.00 Sqm embankment ** Supplying and planting vertiver (Binna) grass in 13,000.00mX12.00 m bunch of 2 to 3 stem @ of 225 mm all over the Sqm 48.00 74,88,000.00 =1,56,000.00 Sqm side slope 2,46,48,000.00
3.Surface Drain and Cross Drain 3.1 Construction of 400 mmX550mm Surface Drain
Earthwork in excavation of drains etc. by 1.15 X 0.7X 13000.00 5.02.01 excavating earth to the lines, grades and = 10,465.00 cubic Cum 78.42 8,20,,665.30 ‐LGED elevation as per drawing, carrying and disposing meter of all excavated materials; Single brick flat soling with 1st class/ PJ bricks, true to level, camber, super elevation and grade 5.03.01 1.15X 13,000.00 in/c filling the joints with sand (FM 0.50) in/c cost Sqm 251.04 37,53,048.00 ‐LGED =14,9500.00Sqm of all materials complete as per direction of the Engineer‐in‐Charge Brick work with 1st class bricks with 6mm thick cement mortar (1.4) for guard wall of drain, foot (2X0.375mX0.25mX1. path and median, filling the interstices tightly m+2X with mortar, raking out joints, cleaning and 0.30mmX0.250mX 5.02.03 soaking bricks at least for 24 hours before use, 1m )X 13,000.00 Cum 4665.16 2,50,16,920.50 ‐LGED washing of sand, curing for requisite period, cost =0.412513,000.00 of all materials, etc. all complete as per direction =5,362.50 Cubic of the Engineer‐in‐ Charge. (Minimum F.M. of Meter sand:
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Cement concrete (1:2:4) with Portland cement, coarse sand (F.M 1.80), First class/ PJ brick chips 1.15X0.075X (25mm to 5mm down‐ graded), cost of materials 5.03.05 13,000.00 and shuttering, mixing by concrete mixer Cum 6362.15 71,33,560.69 ‐LGED =0.08625X13000.00 machine, casting, laying, curing for the requisite = 1121.25 Cum period, etc. as per direction of the Engineer‐in Charge 12 mm thick cement plaster (1:4) in drain (0.300m+0.250m+0.5 including cost of materials, washing of sand, 50m+0.600m+0.250 curing for requisite period, maintaining proper 5.12.01 m+0.850m)X13,000.0 curvatures of corners, side wall and bottom, costs Sqm 172.00 6,26,080.00 ‐LGED 0 of all materials, etc. complete, as per direction of =0.280m X 13,000.00 the Engineer‐in‐charge. (Minimum F.M. of sand: = 3,640.00Sqm 1.2
Sub Total= 3,73,50,274.49 3.2 Construction of 750mmX750mm X 750mm Storm Water Catch Pit at 200.00 Meter Apart 1.050m X 1.050mX Earthwork in excavation of drains etc. by 0.975m X 66 5.02.01 excavating earth to the lines, grades and =1.0749X66 Cum 78.42 5,563.58 ‐LGED elevation as per drawing, carrying and disposing =70.946 Cubic meter of all excavated materials;
Single brick flat soling with 1st class/ PJ bricks, 1.050m X 1.050mX true to level, camber, super elevation and grade 5.03.01 66 in/c filling the joints with sand (FM 0.50) in/c cost Sqm 251.04 18,266.93 ‐LGED =1.1025 SqmX66 of all materials complete as per direction of the =72.765 Sqm Engineer‐in‐Charge Reinforced Cement Concrete in drain work Portland cement , sand (minimum F.M 1.80) 20mm down well graded crushed 1st class brick/picked brick chips (LAA value not exceeding 40) including shuttering, mixing by concrete mixture machine casting , laying, compacting, curing for 28 days, breaking Ist class/ picked brick 0.325 Cubic meter 4.1.10.0 chips etc complete in all respect as per design RCC in each catch pit 2.2 Cum 7270.00 1,55,701.59 drawing, design and drawing , and direction of X 66 LGED Engineer in Charge” and cylinder crushing = 21.42 Cubic meter strength of concrete should not be less than 170 kg/cm2 (suggested mix proportion 1:2:4) excluding reinforcement and fabrication, but including cost of all materials, reinforcement, and its fabrication shuttering, casting curing for 28 days and all incidental charges , 6.051‐ Supplying and Fabrication of M.S high strength LGED deformed bar/Twisted bar reinforcement of size and length for all types of RCC work including straightening the rod, removing ruts, cleaning, cutting, hooking, bending, binding, with supply of 22 B.W.G. GI wire, placing in position, including lapping, spacing and securing them in position by concrete blocks (1:1), metal chairs, etc. complete 167.97kg of MS road including cost of all materials, labor, local in each catch pit X66 kg 67.63 7,49,,747.53 handling, laboratory test, incidentals necessary to =11,086.02 kg complete the work as per specifications, drawings and direction of the Engineer. Laboratory test for physical, strength, elongation % & bend to be performed as peer ASTM. (Measurement will be based on standard weight of 490 lbs./ft3 Chairs, laps and separators will be measures for payment. The cost of these will be included in the unit rate). Sub Total= 9,29,279.62 3.3 Supplying and Fitting and Fixing of 500.mm R.C.C Pipe at 200 meter Apart along the Alignment of the Drain
Page 195 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
Supplying precast RCC pipes(500 mm internal dia,50mm thick) with 12mm downgraded dust free 1st class brick chips (1:2:4)including pipe 12 meter long RCC 6.096‐ mete 2910.8 joint gap filling in neat cement slurry casting, pipeX66 =792.00 23,05,377.36 LGED r 3 curing, laying in position, from finished type by meter steel form works as per design , specifications complete as per direction of Engineere‐in Charg
Single brick flat soling with 1st class/ PJ bricks, true to level, camber, super elevation and grade 3.00 m X 1.50mX.6 5.03.01 in/c filling the joints with sand (FM 0.50) in/c cost =4.5 SqmX66 Sqm 251.04 74,558.88 ‐LGED of all materials complete as per direction of the =297.00 Sqm Engineer‐in‐Charge
Cement concrete (1:2:4) with Portland cement, coarse sand (F.M 1.80), First class/ PJ brick chips 3.00mX1.50mX0.075 (25mm to 5mm down‐ graded)in the foundation 5.03.05 m X66 6362.1 of guide wall, cost of materials and shuttering, Cum 1,41,716.8 ‐LGED =0.3375 SqmX66 5 mixing by concrete mixer machine, casting, = 22.275.5Cum laying, curing for the requisite period, etc. as per direction of the Engineer‐in Charge Brick work with 1st class bricks with 6mm thick cement mortar (1.4) for guide wall of R.C.C pipe filling the interstices tightly with mortar, raking 2.00mX2.50mX0.50m 5.02.03 out joints, cleaning and soaking bricks at least for X 66 4665.1 Cum 7,69,749.75 ‐LGED 24 hours before use, washing of sand, curing for = 2.50 CumX66 6 requisite period, cost of all materials,. etc all =165.00 Cubic Meter complete as per direction of the Engineer‐in‐ Charge. (Minimum F.M. of sand: 12 mm thick cement plaster (1:4) in guide wall including cost of materials, washing of sand, (2X1.00mX2.00m+ 2X curing for requisite period, maintaining proper 0.25mX1.00m+ 5.12.01 172.00 curvatures of corners, side wall and bottom, costs 0.25m X2m)X66 Cum 56,760.00 ‐LGED 15 of all materials, etc. complete, as per direction of =5.00 Cum the Engineer‐in‐charge. (Minimum F.M. of sand: = 330.00 Cum 1.2 Sub Total= 33,48,162.88 3.4 Construction of RCC Drain on the Slope of the Embankment 0.7 m X 0.675mX 11m Earthwork in excavation of drains etc. by X66 5.02.01 excavating earth to the lines, grades and =5,197X66 Cum 78.42 26,898.22 ‐LGED elevation as per drawing, carrying and disposing =343.02cubic meter of all excavated materials;
Single brick flat soling with 1st class/ PJ bricks, true to level, camber, super elevation and grade 0.70m X 11X.66 5.03.01 in/c filling the joints with sand (FM 0.50) in/c cost =7.7 SqmX66 Sqm 251.04 1,27,578.53 ‐LGED of all materials complete as per direction of the =508.20 Sqm Engineer‐in‐Charge Reinforced Cement Concrete in drain with Portland cement , sand (minimum F.M 1.80) 20mm down well graded crushed 1st class brick/picked brick chips (LAA value not exceeding 40) including shuttering, mixing by concrete 0.2310 Cubic meter mixture machine casting , laying, compacting, RCC in per running curing for 28 days, breaking Ist class/ picked brick . meter of drainm X 11 4.2.04.0 chips etc complete in all respect as per design X66 Cum 12,19,222.62 2. LGED drawing, design and drawing , and direction of 7270.00 = 2.541X66 Engineer in Charge” and cylinder crushing =167.706 Cubic strength of concrete should not be less than 170 meter kg/cm2 (suggested mix proportion 1:2:4) excluding reinforcement and fabrication, but including cost of all materials, reinforcement, and its fabrication shuttering, casting curing for 28 days and all incidental charges ,
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Supplying and Fabrication of M.S High strength deformed bar/Twisted bar reinforcement of size and length for all types of RCC work including straightening the rod, removing ruts, cleaning, cutting, hooking, bending, binding, with supply of 22 B.W.G. GI wire, placing in position, including lapping, spacing and securing them in position by 119.57 kg of MS road concrete blocks (1:1), metal chairs, etc. complete in per running meter 6.051‐ including cost of all materials, labor, local of R.C.C drain kg 67.63 58,70,812.87 LGED handling, laboratory test, incidentals necessary to X11mX66 complete the work as per specifications, drawings =1315.27kgX66 and direction of the Engineer. Laboratory test for =86807.82 kg physical, strength, elongation % & bend to be performed as peer ASTM. (Measurement will be based on standard weight of 490 lbs. /ft3 Chairs, laps and separators will be measures for payment. The cost of these will be included in the unit rate). Cement concrete (1:2:4) in Spill way with Portland cement, coarse sand (F.M 1.80), First 1.00mX1.00mX0.150 class/ PJ brick chips (25mm to 5mm down‐ 5.03.05 m.X 66 graded), cost of materials and shuttering, mixing Cum 6362.15 62,985.29 ‐LGED =0.150CumX66 by concrete mixer machine, casting, laying, curing = 9.90 Cum for the requisite period, etc. as per direction of the Engineer‐in Charge
Sub Total= 73,07,497.52 28,33,75,736.5 Total= 0
Page 197 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
Appendix VI: Comment Matrix Comments from BWDB and Observance Summary • JMREMP Manual should be followed for design of Protective Work. • Data & Information of Design Manual of FAP21/22 was not authenticated by its author. So, Designer should be careful in using Data & Information of this manual. • Actual & current Data should be used for design instead of assumed & old data. • All Calculation sheet including Hydrological & Metrological analysis should be enclosed with Design Report. • Design Criteria should be selected carefully. • The River Section at Chouhali, Zafargonj & Harirampur used in this Design Report does not represent the actual River Section. Actual Section should be used for design of Protective Work. • River Sections are not drawn correctly from data printed in Technical Drawing. River Section should be drawn correctly as per field survey data. • Before implementation of Harirampur Protective Work, the adjoining area should carefully be studied. It should be checked, whether there are any conflicts between Harirampur Protective Work & Regulator (proposed) at Kaishakhali Closure point. • Drainage Discharge of Regulators of Hurasagar FCD Project should be determined carefully. Because there are no proposal of embankment was found on the northern & western side in this report. • All Design Report & computation sheet should be clear & self‐explanatory with reference (where required). These Reports should be preserved in Design Library for ready reference. • "Annex B Data & Survey", "Annex D : Hydrology & Flood Modeling" and "Annex E River Hydraulics & Morphology" should be send to this office Article or item wise comments are given below 1. Annex F2 Chapter 4 : River Bank Protection Work(Page 21‐30) In this report, in most cases Design Data are collected from FAP21/22 Manual & some other sources which are not updated with up‐to‐date Hydrological & Metrological Data. Design calculation should be done considering up‐to‐date Hydrological & Metrological Data and respective design calculation should incorporate in Design Report
COMMENT REPLY • HFL, LWL & Discharge ( Art 4.5 & 4.6, Page 23‐25): Current HFL, LWL and Discharge were analysed. The In this report, all data of HFL, LWL & Discharge are assumed results are shown in the design criteria, section .1.4. or collected from some previous report. As those reports are very old, they do not contain current data. e,g Q of Jamuna (1:100 year ) =1,00,000cumec was mentioned in this report. But if we consider current data then Q of Jamuna at Bahadurabad (1:100 year) will be 1,12,865 cumec. For effective design, analyses with current Hydrological Data are required. Current primary data are available in Hydrology Directorate of BWDB. So, to address current hydrological scenario primary Hydrological Data (including current Data upto 2013) should be collected and analyze it for Design .HFL, Design LWL & Design Discharge. These Hydrological Calculations should be enclosed in Design Report • Flow Velocity (Art 4.7, Page 25) Flow velocity collected from BWDB measurement is Flow Velocity is a key factor to determine stability & size of presented in the design criteria section 1.4. Flow protection clement. In this report, Velocity data are velocity measured at Bahadurabad in Brahmaputra‐ assumed or collected from some previous old report. Flow Jamuna River and that at Baruria in Padma have Velocity of Padma at Harirampur was determined on the been used. The selection criteria is explained in the basis of velocity of Meghna at Haimchar & Chandpur. For Design note. effective design, site specific velocity is essential and Designer should be more careful in selecting Design Velocity. Some Velocity Data are given below for information
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COMMENT REPLY
Hydrology,BWDB Padma Bridge Velocity (m/s) Bahadurabad Baruria Transit Mawa Mawa (1:100) Max = 3.68 Max =4.23 Max =4.35 Max = 4.60 June To Min =3.00 Min =3.00 Min =3.02 Min = September Average=3.28 Average =3.37 Average=3.45 Average =
Maximum Velocity: JMREMP Manual, P‐122: (as per FAP 24) Jamuna: Kamarjani = 3.2 m/s Bahadurabad = 3.7 m/s
Ganges: Gorai offtake = 4.0 m/s • Bed Material Size & Silt Factor ( Art 4.8, Page 27) Size of bed material has been taken from FAP24 and Bed Material Size, D50 is a Key factor to determine Scour FAP 1 report, checked with FAP‐21 Design Manual Depth. For effective design site specific & correct D50 and IWM report on Flood Control Embankment and should be used. But in this report, some assumed value River Bank Protection of the Left Bank of Jamuna from previous report has been used. So, site specific & River at Nagarpur and Chouhali; There are no recent actual D50 should be used. D50 for each site may be measurements. determined from field sample. • Waves ( Art 4.9, Page 28) Wave height has been taken from the Special Waves i.e. Wave Height & Wave Period is a Key factor to Report 23, design brief for Riverbank Protection determine size of protection element. In this report, implemented under JMREMP (update),Dec 2006 and assumed Data of Wave Height & Wave Period are copied verified with JMREMP Design Manual and FAP‐21 from FAP 21 Manual (2001). That report is also an older design Manual. Finally the highest wave suggested one. Instead of assuming Design Data, primary Data by FAP‐21 Design Manual for 100 year return period (including current Data upto 2013) from Metrological is selected. The baser pape prepared by Dennis Department can be collected and analyzed it for Design Grosser is enclosed as Appendix‐IV (Attachment‐2). Wind Speed & Design Wind Duration. Design Wave Height & Wave 'Period can be calculated from Wind Speed. Wind Duration and Fetch Length. These Calculations should be enclosed in Design Report • Scour Depth (Art 4.811, Page 27) The scour value has been assumed from the survey Discharge, bed material size & Lacey's Factor are key data conducted under the project. The selection of element for calculation of Scour Depth. in this report Scour data is site specific. The design being a feasibility Level at Chouhali was calculated as ‐12.90m(PWD) by level one, generalised data received from the survey considering Q= 36000 m3/s, (D50 =0.18mm & Lacey's has been used. The general scour has also been Factor = 1.5. But observed Lowest Scour level at. Chouhali verified with the historical data taken from BWDB is ‐31.34 m(PWD) as per BWDB Field data. It reveals that cross‐section. value of Discharge, Bed material size & Lacey's Factor are In using the Lacey's scour formula attention is given not considered properly. In this report Q= 36000 m3is has on the share of discharge carried by the particular been considered instead of actual discharge of Jamuna is channel. Limitation of applying Lacey's formula is 1,12,865 cumec (100year). Near Chouhali Upazila Complex, also considered in applying in a braided channel. tere is a right angle turn in river bank. In this case Lacey's Factor will be 2.00. If we :x.‐aisider Q= 1.12,865 m3/s, d50 During the detail design the specific area has to be =0.18mm & Lacey's Factor = 2.00 then Scour Level comes to addressed with the scour measured in that area plus ‐36.07 m(PWD) which is closer to observed one. an allowance. From this report it is also found that Calculated Scour Level at Harirampur is ‐ 25.00 m(PWD), but observed lowest Scour Level is ‐37.00 m(PWD). Some .more Observed Scour Level are described as below
Location Sirajgonj Sailabari Mawa Observed scour level(m PWD) -33.00,-44.00 -40.00 -50.33
Moreover during design it may be found that there is Moderate Bend in River bank and flow is parallel to Bank.
Page 199 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
COMMENT REPLY Under this situation Designer may consider Lacey's Factor = 1.5. But during or after execution, it may happen that there is an oblique flow due to formation of a char or change in river bank from moderate bend to severe bend or right angle. In this changed situation Lacey's Factor will be5 1.7 or 2.00. So, Discharge, Bed material size & Lacey's Factor should carefully be selected during design. • Size & thickness of protection Element (Art 4.12, Page 29) In calculating geobag size and thickness Pilarczyk It is to be noted here that USACE Equation & JMBA equation and JMREMP manual has been followed. Equation is not applicable for Geobag • Khoa Filter ( Art 4.13.1, Page 29) Geotextile filter has a filter quality both along and From this report and Drawing it is found that Geotextile & across the fabric. Moreover geotextile is laid on a sand has been used as filter. But Khoa Filter does not used. 50mm thick sand bed which will act as additional BWDB Manual, JMREMP Manual and other manual filter as well as it will protect gotextile against suggested for using Khoa Filter. So, explanation is needed clogging. for not using Khoa Filter above Geotextile. In JMREMP work in general no khoa filter was used. Khoa Filter does not comply with the Terzaghi Filter rule. • Size of Geobag ( Art 4.13.2 & 4.13.3, Page 30) Flow velocity considered for selecting size of From this report it is found that 125kg Geobag will be used protection element (geobag) is sufficient for the in Area Coverage & Launching Apron, 250kg Geobag will be stability of 125 kg geobag. 250 geobag shall be used used in protrusion. But JMREMP Manual recommended for only if there is higher velocity, which normally is not using of single size of Geobag. Moreover supporting expected during execution of the work. It is required calculation for 250 kg Geobag has not been furnished. only to meet the emergency. Supporting calculation should be enclosed for 250 kg Geobag • Sequence of Implementation The active erosion zone and its extent at present Sequence of Implementation of Protective Work for a large has been selected for providing protection under the reach like 5.00km in Chouhali and 7.00km in Harirampur project. The probability of continued erosive attack may be discussed here has nalso bee considered through morphological studies. Annex F2: Appendix ‐1 Sample Calculation for Chouhali (Page 79‐93) • HFL, LWL & Discharge (Page 35) : Response placed above Comments same as above in Sl no. 1 • Velocity (Page 35) Selection of velocity is explained above here Average Flow Velocity has been considered as 3.00 m/s. But there is no supporting explanation for determination of such velocity. From JMREMP Manual Velocity of Jamuna at Kamarjani is 3.20m/s & Bahadurabad is 3.70 m/s, Moreover according to Data of Hydrology Directorate, Velocity of Jamuna is as below Velocity (m/s) Bahadurabad Baruria Transit June Max= 3.68 Max= 4.23 To Min= 3.00 Min= 3.00 September Average=3.28 Average=3.37 Velocity of Jamuna at Chouhali can also be measured at site. Velocity is a very important Design Data, because it determines the size of protection element. So, Design Velocity should be carefully selected. In page 26, Art 4,7.2, it is mentioned that 3.00 m/s velocity has been considered in straight reach and 3.50 m/s velocity has been considered for acute bend and protrusion. But 3.50 m/s velocity has not been used during calculation of size of CC block or Geobag. • Bed Material Size, D50 (Page 35) Bed material selection is explained above
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COMMENT REPLY As it was discussed in Art 4.8, Page 27 of this report, Bed Material Size 0,18mm is assumed from some previous report. For effective design, site specific & actual D50 should be used. Actual D50 Data are essential for correct Scour Depth. D50 for each site should be determined from field sample
Padma Halcrow jamuna,jmremp manual JMREMP Manual
Bridge For Jamuna 1:100 1:25 PIRDP MDIP
Hs(m)= 1.40 1.00 1.30 1.00 1.00 1.25
Tm(sce)= 3.40 3.00 3.40 4.20
• Wave Data (Page 36) Wave data and its method of calculation is Here Wave Height = 1.30 m has been used from FAP21 explained above and reference appended. Manual (200l). This is an old data. Wave Period 2.45sec used has been used from JMREMP Manual (2010). Updated Metrological Data should be used for determination of Design Wind Speed & Design Wind Duration and subsequently Wave Height & Wave Period. Calculation sheet in this regard should be enclosed with Design Report. Some Data of Wave height & Wave Period from previous manual are given below for information • Lacey's Factor (Page 36) Explained above Here River Bank has been taken as Moderate Bend. Some part of River Bank may be have Moderate Bend at U/S Location. But at present, at Chouhali Upazila Complex, there is a sharp right angle turn. At D/S of Chouhali Upazila Complex, there is severe Bend. So, Lacey's Factor should carefully be selected. Moreover Drawing of this Protective Work should contain a Plane Table Survey & current Satellite Image showing Bank Line • Scour Level (Page 35,47) Selection of scour depth explained above. Here it is mentioned that maximum observed Scour Level is ‐3.00m(PWD). Calculated maximum Scour Level is ‐ 12.90m(PWD). But in the attached Technical Drawing, maximum observed Scour Level is ‐9.87 m(PWD). Moreover according to Data supplied from field office to Design Circle ‐1 , maximum observed Scour Level is ‐31.34m(PWD). So, Discharge, Bed material size & Lacey's Factor should carefully be considered during calculation of Scour depth. • JM BA Equation (Page 36) JMBA equation suggests to use h/d = 5. Here h/d= 5 has been assumed. Valid justification should be For geobag size selection JMBA equation has not provided for this assumption. It is to be noted that ,JMBA been used. Equation is not applicable for Geobag • Dn in Pilarezyk Equation (Page 37) Geobag is not a cubical element, so equivalent In.1 JMREMP Manual Dn has been defined as "Equivalent cubical size is used as an unit of size. Finally Diameter". But in this report Dn has been defined as equivalent diameter has been used in calculation. "Nominal thickness of protection unit". This matter Should he clarified. • Average Water Depth in Pilarczyk Equation (Page 37) 6.0 m being the average depth over the protection Here average Water Depth, h = 6.00 m has been element used for areal coverage and launching considered. How h = 6.00m has been selected, supporting apron. The lower depth is chosen as it provides a calculation should be given. In JMREMP Manual h' defined moderately higher size of protection elements. And as "water level at toe of slope". But in this report h' has therefore is on the safer side. been defined as "Average Water Depth". This matter
Page 201 PPTA 8054: Main River Flood and Bank Erosion Risk Management Program
COMMENT REPLY should be clarified • Angle of Repose used in Pilarczyk Equation (Page 37‐39) The protection element in areal coverage and Value of Angle of Repose for different protection element is launching apron is not supported by any type of mentioned in FAP21 Manual & JMREMP Manual. But in this filter. Hand placed cc blocks proposed for slope report those values are not used in all cases. Some protection above LWL is placed on filter. examples are given Below Considering all these factors the angle of repose
Protection Used in FAP21 Manual JMREMP Manual suggested by Pilarczyk for Geobag, Inglish for rocks Element this Report Geotextile Granular and worked out example in FAP‐21 Manual for CC CC 40° 30° 35° - - Block,multi block has been consulted for selection of angle of -layer Rock 35° 20° 25° Riprap 40° repose of a protection element and its use. 40° 20° 25° - - CCblock hand placed Single layer Geobag 30° Sand filled 30°-40° system
Source of value of Angle of Repose used in this report should be mentioned • Thickness of protection above LW L(Page 44‐45) Protection thickness was decided in consideration In this report, Maximum Thickness of Protection was of 2 layers of dominant size of protection element. calculated as 400mm from stone size consideration and This is already explained in the design sheet. Maximum Thickness of Protection was calculated as 2170mm from stream flow consideration. But Protection thickness was selected as 400 mm. The explanation for selecting lower thickness is not clear • Thickness of CC Block Protection Below LWL (Page 46) ‘BERT te Slaa’ in ”River Training Works for In art A.2.2 it is mentioned that Thickness of Protection by a Bridge acrossthe Brahmaputra River, CC Block should be 3D to accommodate winnowing effect. that the total thickness of Basis of such assumption or source should be mentioned Bangladesh”, stated here. an "all in" filter should be approximately five In writing, it is mentioned Thickness of Protection by CC times the diameter of a single rock which can just Block should be 3D +50%. But calculation was made as withstand the current forces. Thickness = 4.5D. So, Clarification or correction is needed. Moreover this calculated thickness i.e. 3.5D or 4.5D has not 3D+ 50% additional shall be (3+1.5)D = 4.5D, no been used in drawing. drawing has been produced with cc blocks in areal In calculation, it is written that 2 layer of CC block should be coverage or in launching apron. dumped over Geobag. For 2 layer,2 22.2 nos/sqm CC Block should be dumped. But in drawing it is written as The statement is made to cover the eroding 16nos./sqm. So, Clarification or correction is needed surface by material of uniform size on a geobag filter. Under this state the cover by minimum 2 layers of cc block has been made on top of a filter layer. The void in this case will be around 40%, but in this case a very conservative assessment has been made with a void of about 28% percentage.
All other inconsistencies will be taken care during detail design. • Flatter slope in River Bed Level (Page 47) Slope after ‐3.00 is slightly flatter than 1V:5H Here it is considered that after 0.00 m(PWD), River Bed is Flat. From Section it is prevails that it is not correct • Areal Coverage & Falling Apron(Page 47) Length of areal coverage is the main factor. It is Here Length of Areal Coverage & Falling Apron selected selected in a way that any scour cannot occur near arbitrarily. Areal Coverage are considered from 3.00 the bank to induce any slope failure. 15 m apron is m(PWD) to 0.00 m(PWD) & Length of Areal Coverage was proposed to take care of any scour that can occur in selected as 30m. But as per enclosed cross section of a season. Chouhali, inclined length from 3.00 m(PWD) to 0.00 In Jamuna river it is observed that a maximum of in(PWD) tis abou 12.37m & 4.42m. Length of Falling Apron 15,0 m of scour can occur in front of a revetment in
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COMMENT REPLY was selected as 15m. Selection of Length & Description of 90 days i.e. in one monsoon season. Please Refer to Apron written here does not comply with section & Padma Bridge Design Report, Annex E. calculated of Scour Depth of this report. So, Clarification or correction is needed. • Volume of Rock above LWL(Page 48) The material is calculated on 1V:3H slope, this also From Page 45, Thickness of Protection above LWL = 400 accounts for 1,5m horizontal cover on the flood mm So, Volume of Rock above LWL = (11‐5) V 10 x 0.4 = plain. 7.59 m3/m But this Volume is written here as 11.95 m3/m. So, Clarification or correction is needed • Volume of Rock in Falling Apron In Page 47‐ 48, it is written that Launching takes place normally in single layer. This o Areal Coverage will be provided from LWL (+3.00 in, has to be upgraded in subsequent stages. Proper PWD) to 0.00 m(PWD) monitoring and follow up is needed to take care of further upgrading after initial launching of material. o Falling Apron/Launching Apron is proposed to be placed at the end of Areal Coverage. o Calculated Scour Level is ‐13.00 m(PWD). o Thickness of Protection (pitching), T = 520mm o Thickness of Protection, 1.5T = 780mm o Volume provided in Falling Apron = 15 x 0.78 = 11.70m3/m o D = 0.00‐ (‐13.00) = 13m o Apron will be Launch in 1V:2H slope. Launched slope Length ( if it Launched in IV:2H slope ) =13 x 2.24 = 29.12m. In that case, thickness of protection after launching will be =11.70 / 29.12 = 0.402 m. This thickness is less then Design thickness (0.520 m). Whether this thickness is acceptable. Clarification or correction is needed • Volume of Geobag in Falling Apron In addition to above, in Page 48, it is written that Placed apron thickness is 510mm i.e. 3 layers of o Thickness of Protection by Geobag, 3 Layer = 510 m/m 125kg geobags. o To ensure 3 layer, additional 1 layer should be used. o Volume provided in Falling Apron = 15 x 0.51 x 1.33 = Explained above 3 10.17 m /m Launched slope Length ( if it Launched in 1V:2H slope ) =13 x 2.24 = 29.12m. In this case, thickness of protection after launching will be =10.17 / 29.12 = 0.349 m. This thickness is less then Design thickness (0.510 m). Whether this thickness is acceptable. JMREMP Manual recommended that, "Systematice coverag by minimum 3 layer Geobag may provide a dependable protection." Clarification or correction is needed. • Extra Volume of Geobag In Page 48‐ 49, 33 % extra Geobag has been considered in Areal Coverage & Falling Apron. Basis of such assumption or source should be mentioned hare. In JMREMP Manual it was recommended that o Systematic coverage by minimum 3 layer Geobag may provide a dependable protection. o To ensure 2 layer at least 4 layer Geobag needed to be placed systematically So, by logic, from the above recommendation it reveals The recommendation is given as per achieved in that to ensure 3 layers, at least 5 or 6 layer geobag needed JMREMP. 3 layers of geobag if properly placed can
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COMMENT REPLY to be dumped systematically. It will be helpful, if the matter serve the purpose. No need of extra coverage. so is clarified. provision of 4 layers is made to take care of any uncertainty. Reference is available in Padma Bridge Final Design Report Annex E • End Termination The work is proposed to be extended in next tranch. End Termination at both ends of Protective Work has not So end termination is not proposed. In JMREMP also been considered. How both end will be protected against no end termination has been provided, rather the out flanking. It will be helpful, if the matter is clarified. protection limit is extended beyond the critical zone. From the Design Computation of Chouhali‐Nagarpur following question arises • How Areal Coverage & Falling Apron will be differentiate Already explained above. Moreover, designers or identified in judgment shall be applied in case of varying the different River Section. width of areal coverage. • How Length of Areal Coverage will be determined. Explained • How Length of Falling Apron will be determined. Explained • How Volume of material in Falling Apron will be Explained determined. Does this volume will be calculated on the basis of Lowest Scour Level. • JMREMP suggested 3 layer of Geobag. How this 3 layer Explained will be ensured during dumping at different depth, different flow condition etc 3. Annex F2: Appendix VI : Technical Drawing Chouhali‐Nagarpur • In the Drawing LWL = 5.50m(PWD) has been used. But in Shall be taken care in detail design. This has been calculation LWL = 5.00m (PWD) has been used (Page 35,46). corrected in the report. It should be corrected • Original River sections are not visible • Drawing of Chouhali‐Nagpur, Section‐1 & Section‐2 does These are Feasibility level designs. Shall be taken not match with the RL, written there (copy enclosed). It care after a detail survey during final design stage. should be corrected. Moreover these section are incomplete, Because Elevations are written from 0.00 m (PWD) to towards River Bed. In the design sheet (Page 35), Average Bank level was Written as 11.00 m(PWD). So, Elevation should be written at least from Average Bank level i.e. 11.00 m(PWD) to towards Lowest River Bed and section should be drawn correctly in 1H: 1V scale. • The Section‐1 & Section‐2 enclosed in Technical Drawing The sections are based on river surveys in 2011 and does not represent the actual River section. Design & 2012 flood season. Drawing should be made on the basis actual section. Estimate should be prepared on the basis of that drawing • At Chouhali Upazila Complex, different buildings are The Buildings are currently eroding. situated just at the bank line. If during design, it was attempt to make a 1:3 slope line above LWL then this building have to be demolished. But it will be very difficult to demolish those building. This critical matter should be addressed carefully during design & implementation Zafargonj: Original River sections are not visible. Moreover The river bank will be surveyed during the detailed these section are incomplete, elevations are written from design. 0.00 m(PWD) to towards River Bed. Elevation should be written at least from Average Bank level to towards Lowest River Bed In Section‐3 it was found that 2 layer 250kg Geobag will be The base layers consisting of smaller sizes dumps dumped over 1 layer 125kg geobag. During dumping, how, assures that there are less gaps in the critical area. position of 2 layer 250kg Geobag will be ensured over I layer 125kg Geobag. Moreover ,IMREMP Manual suggested
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COMMENT REPLY for using Single Size of geobag, The Section‐I, Section‐2 & Section‐3 enclosed in Technical The sections are based on river surveys in 1201 and Drawing does not represent the actual River section. Design 2012 flood season & Drawing should be made on the basis actual section Estimate should be prepared on the basis of that drawing. Al Zafargonj Bazar, different shops are situated just at the bank line. If during design, it was attempt to make a 1:3 slope line above LWL then this shops have to be demolished. But it will be very difficult to demolish those shops. This critical matter should be addressed carefully during design & implementation Benotia The sections are based on river surveys in 2011 and Original River sections are not visible. Drawing of Benotia, 2012 flood season Section‐1 does not match with the RL written there. In the Drawing, Elevation of Flood Plane is 9.60 m(PWD). But in the drawing, RL is written from 4.78 m(PWD) to ‐0.86 m(PWD). So, Elevation should be written at least from Average Bank level to towards Lowest River Bed. Design & Drawing should be made on the basis actual section. Estimate should be prepared on the basis of that drawing Harirampur The sections are based on river surveys in 2011 and Original River sections are not visible. Drawing of 2012 flood season Harirampur, Section‐1 does not match with the RL written there (copy enclosed). Elevation should be written at least from Average Bank level to towards Lowest River Bed. From the section it is found that LWL= +2.00 m(PWD). But Existing RL ism written fro ‐1.39 m(PWD) to ‐2.74 m(PWD). These RL does not reflect a section. Design & Drawing should be made on the basis actual section. Estimate should be prepared on the basis of that drawing In Section‐I it was found that 2 layer 250kg Geobag will be See earlier explanations. dumped over 2 layer 125kg Geobag. During dumping, how, position of 2 layer 250kg Geobag over 2 layer 125kg Geobag will be ensured. Moreover JMREMP Manual suggested for using Single Size of Geobag From Index map, it was found that location of protective There are no plans to close the offtake. work at Harirampur is at the oftake of Ichamati River. From Index map in Technical Drawing, it seems that Harirampur Protective Work will close the oftake. It is to be mentioned here that previously Ichamati River was closed by Kaishakhali Closure. Kaishakhali Closure is approximately 7.00 to 8.00 km D/S of Harirampur Protective Work. Presently people of Dhohar & Nawabgonj are demanding for opening the Kaishakhali Closure and they demand for a regulator at that point. So, before implementation of Harirampur Protective Work, the adjoining area should carefully be studied. It should be checked, whether there are any conflicts between Harirarnpur Protective Work & Regulator at Kaishakhali Closure, point and some other 3 Flushing Gate in that area. I, Annex F2: Chapter 2 Embankment (Page 49‐56) In Art 2.3.1, Page 7, Factor of Safety =1.4 has been The FS has been considered in line with the considered for slope stability. But normally this Factor of standards followed in JMREMP. Safety is considered as 1.5. Moreover Bishop Method or Jamboo Method is used for calculating Slope Stability • 5.30 in Carriage way has been provided on C/S slope of Road section as per type‐5, (minimum width of 2 embankment. In page 9, it was mentioned that lane carriage way, Ref: Geometric Design of RHD
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COMMENT REPLY specification of Rural Road of RHD has been used for this Roads‐2005) is 5.5m carriage ay + 2x1.2 m shoulder Carriage way. According to a Praggapan of Road Transport + 2x0.95m verge, in total 9.8m; this has been made Wing of planning Commission, Road Class : Rural Road‐1 10.0m with 2x1.5m paved shoulder and 2x0.75 m has been replaced by Design Type 8. But the Drawing of verge. Carriage way (Detail 'D') as enclosed in Technical Drawing does not match with Design Type 8, So, Clarification or correction is needed. • As the fill material of embankment is dredge fill soil, The seepage issue has been addressed in the attention should be given to Seepage analysis. In some geotechnical assessment Book Slope of seepage line for sand was mentioned as 1:15, • In Annex Fl, Page 25, value or initial void ratio eo, The values were taken from the laboratory analysis Compression Index, Cc, Sp gravity Gs & Unit Weight etc. has on the selected sample. As a feasibility study been assumed for settlement calculation. But these values analysis selected area has been analysed. Further, of each layer of foundation soil should be obtained from elaborate study will be made during detail design laboratory test report or field soil sample stage. Annex F2: Appendix VI Technical Drawing (Embankment) • Details of 10cm RCC at Crest of Embankment has not RCC road detail will be shown during detail design been shown. This RCC Work may be avoided. This work is stage. duplication with US carriage way. Embankment can be monitored by this carriage way. Moreover if RCC was road was constructed over crest then it will be difficult to rise the embankment height in future (if needed). • Details or Verge & Shoulder (Detail ‘D') have not been The drawings have been expanded with these shown. Moreover same item has been shown for Shoulder details. & Road. • C/S Slope has been considered as 1:2 when height is 4.00 River side slope is 1V:3H and country side slope is m and 1:2.5 when height is 3.00 m. So, Clarification or 1V:2.5H correction is needed Crest width of Embankment (3.20m or 3.21m), Width of R/S 3.20 m is the crest width, width of slope shall be as slope (10m or 8 m) should be corrected per slope provided. • At the bottom of embankment 1.00 base stripping has The cladding will reach to the bottom of the been considered. This 1.00 m will be filled by dredge fill excavation to avoid this. soil. If the embankment and & WS end of base cannot be covered properly by clay cladding (Detail E) or other similar method, then there is a possibility of seepage through this base. This may be a cause of failure of embankment Annex F2: Appendix II: Gala Regulator (Page: 94‐122) • In page 51, it is mentioned that Drainage area outside the The Hurasagar subproject (proposed to be restored) catchment Area is 0.00. But from the project map (Page 18) is protected against flood by embankment along it is found that there are embankment on eastern side & Brahmaputra‐Jamuna, Hurasagar‐Baral and part of southern side, no embankment on northern & western Karotoa river. side. How intrusion of flood water from northern & western side will be prevented. So, Catchment area as well as Discharge should be considered carefully • For Drainage & Flushing condition inside WL & outside WL As a feasibility level design the selection of runoff is should be selected carefully from Hydrological Analysis. described. Hydrological Analysis should be incorporate in this report • Foundation Design has not been enclosed here. Will taken care of in detail design stage. Based on Foundation Design is very important for correct estimation survey analysis. Annex Fl: Chapter 5: River Bank Stability (Page 22‐28) • In Page 28, here it is mentioned that maximum river Statement made on cross‐section surveyed under depth is 18 m and river slope is 1:5 to 1:1. But at some the project and the observation is site specific. places river depth is more than 18 m. In many case side slope is very steep and slope less than 1:1.
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COMMENT REPLY In Slope Stability Analysis, pure Clay & pure Sand have been With the presence of cohesive properties the soil considered. But from the Bore log in Table 2‐5 to 2‐12, Clay sample is considered as clayee material. The mixed with Fine Sand was found in 2 (two) Bore hole. In properties are assumed from the laboratory most bore hole, soil is a mixture of Fine Sand & Silt. In no analysis. Bore log there are pure Sand or pure Clay. Moreover in all Bore log, Soil Type Was defined mostly as Fine Sand Soil Type describes in Table 2‐5 to 2‐12 should match with Noted, shall be taken care in the detail design stage. Bore Log shown in Fig 3‐1 to 3‐4. Moreover Soil Type describes in Table 2‐5 to 2‐12 should match with soil composition stated there • In Page 29, Unit Weight, Angle of Internal Friction & Explained above Cohesion for each layer has been assumed for pure Sand & pure Clay for Slope Stability analysis. But value of Unit Weight, Angle of Internal Friction & Cohesion for each layer should be obtained from laboratory test of field soil sample. In Page 29, ordinate of Fig 5.3 & 5.4 is not clear Ordinate shows the safety factor
• Here. two depths (19m, 39m) of River Bed have been One low and one high (i.e. two extremes) are considered for Slope Stability. It will helpful for design, if analysed. some more depth such as 25m, 30m, 50m etc may he analyzed for Slope Stability. • Here Allowable Factor Safety for Slope Stability was not Explained earlier clearly mentioned. According to BWDB Manual & other literature, Allowable Factor Safety is 1.5. • It is not clear how FS = 1.5% g and FS = 5% g has been Earthquake impact is calculated as per calculated. A sample calculated may be attached. recommendation of BNBC and also a higher factor like 5%g in line with JMREMP • It will he better to understand, if Range of Starting Point noted & Range of End Point i.e. limit of different Slip Circle are mentioned in this Report. • Findings from Table 5‐1 & 5.4 may be described in a noted bullet form, some are mentioned as below. o FS increases with the increase of River Depth o FS increases with the increase of thickness of top clay layer upto 5.00m. If thickness of top clay layer exceeds 5.00m, then FS decreases. o When side slope is 1:2, then FS cannot meet the minimum limit o When side slope is 1:3, then FS satisfies the allowable limit, during design condition Moreover it will be helpful for designer, if this report can make a strong recommendation regarding the design side slope in Protection work • An analysis may be incorporate here, regarding the Will be addressed in Detail Design Stage stability of Slope when it builds with local earth or gunny bag or synthetic bag. This is a common phenomenon in River Bank Protection Work. • In Page 29, it was mentioned that Slope Stability analysis Software was down loaded from internet was done by software Visual Slope, developed by Loveland, Ohio, USA. As a part of Technology Transfer this software may be supplied to Design Office. N It is to be mentioned here that Only "Annex F" has been These annexes were handed over during the
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COMMENT REPLY sent for comment. Data & Information of "Annex B Data & meeting with the design team, in the office of the Survey", "Annex D : Hydrology & Flood Modeling" and Project Director on 28 July 2013. "Annex E : River Hydraulics & Morphology" are required for better understanding of "Annex F", So, "Annex B : Data & Survey", "Annex D : Hydrology & Flood Modeling" and "Annex F; : River Hydraulics & Morphology" should be send to this office, Comments on Draft Final Report of Technical Design and Drawings for "Main River Flood and Bank Erosion Risk Management Program"
The stretch from Sirajganj to Enayetpur is already 1. The proposed embankment is designed with under extension. The top width is 6.0m and has a carriage way and short top width e.g.3.21m, 3.5m additional carriage way for NMV. and a berm of 5.2m for a length of 12.5km. On the other hand the total length of embankments on right bank of Brahmaputra is about 220km (designed by BWDB) and the designed cross section is top width‐ 5.00m and side slopes 1:3. As the new embankment is to be connected with the old embankments and the old embankment section is enough to withstand the water pressure and seepage, hence the embankment section may be provided which is compatible with the embankment implemented by BWDB.
2. In the design, standard and extended section is The point is not clearly understood. mentioned, which is not clear. The basis of extended section is not specified in the design
3. Statistical analysis and simulation of 2D model result 2D model results have not been used, as the design is not clearly discussed. was based on observed river condition.
4. The analysis for the sea level rise is not In BRE sea level rise has not been considered. It is incorporated in the calculation. This should be rather left with 1.5m free board on 100 year HFL. incorporated in the Draft Final Report
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