Job No. PECS2016001 Doc No. PECS/201601/APPROACH JETTY/007 Rev. No.0 Survey, Design, Construction, Supply, Erection & Commissioning of Raw Water Intake Structure (Fixed type), Pump House on Intake structure Project Title including Pumping Machineries with all related Accessories, Raw Water Transmission Main for drawing 35 MGD Raw Water from The River Hooghly and Delivering to Water Treatment Plant on EPC Turnkey Basis Owner Superintending Engineer, Eastern Circle, Public Health Engineering Dte., Govt. of WB Design of Approach Jetty for Intake WAPCOS LIMITED (A Govt. of India Undertaking) Pump House (Habra Gaighata Intake Owner's Consultant Executing Agency Simplex Infrastructures Limited Consultanct to EA Projectscape Engineering Consultancy Services Private Limited Project) Name of Unit Structural Analysis & Design of Approach Jetty (Calculation of Scour Depth) Drawing Ref. Designed by: Shubhajit Barik Checked by: G Chakraborty Approved by: G Chakraborty Date: 9/6/2016 Reference CALCULATIONS CALCULATION OF MAXIMUM SCOUR DEPTH VIS-A-VIS SCOUR DEPTH CALCULATED BY KoPT FOR HABRA-GAIGHATA INTAKE PROJECT : CALCULATION OF SILT FACTOR ( Ksf ) : Ksf = 1.76√dm ( As per clause No. 703.2.2 of IRC:78-2014) dm = weighted mean diameter of bed material in millimetre (The recommendation of KoPT as per letter no: Hyd/ 12029/Jubilee bridge/PHED/862 on Dated: 02.08.2016 the value of dm along the region has been considered as 0.119 mm for the purpose of scour depth calculation.) dm = 0.119 mm So, Ksf = 0.607 CALCULATION OF SCOUR DEPTH 40.0M FROM HIGH BANK LINE W.R.T.HHWL (for 1000Ø Pile) High Bank line has been considered (Refer Sketch No. PECS/SIL/1601/003/SK-01 as wetted line where HHWL merges with the River Bed profile near bank Maxm Discharge Velocity, V = 1.50 m/sec (Recommendation of KoPT as per Letter No. Hyd/ 12029/Jubilee bridge/PHED/862) Discharge per M width of waterway (Db) =(A x V) = 3.76 cumecs Depth of Water considered for unit discharge from HHWL = 2.508 m (at centre of farthest pile nearly 40.0 m away from High Bank Line, 4.67m - 2.162m) So, Design Discharge per M width of waterway = 4.89 cumecs Increase of 30% over Design Discharge, as per clause No. 703.1.1 of IRC:78-2014, Catchment area less than 3000 km2 MEAN SCOUR DEPTH (dsm): As per IRC: 78-2014 the mean scour Depth below Hight Flood Level (HHWL) can be calculated theoritically from the following equation: dsm = 1.34 (Db /Ksf) 1/3 dsm= Mean depth of Scour Db = The design discharge for foundation per metre width of effective Waterway Ksf = Silt factor for a representative sample of bed material obtained uptothe level of anticipated deepest scour. Here, Mean Scour Depth, dsm= 2.686 m (From HHWL) Maxm Deoth of Scour from HHWL (2dsm) = 5.372 m ( As per clause No. 703.3.1.1 of IRC:78-2014) 1.a) Maxm Scour Depth From HHWL = 5.372 m (As calculated above) 1.b) Max Scour Depth From river Bed Level = m 2.180 m (The recommendation of KoPT as per Letter No. Hyd/ 12029/Jubilee bridge/PHED/862 on Dated: Calculated Maxm Scour Depth From HHWL (2.18+2.508) = 4.688 m 02.08.2016 So, for Design purpose we would consider the Maximum Value = 5.372 m from HHWL Page 1 of 2 Job No. PECS2016001 Doc No. PECS/201601/APPROACH JETTY/007 Rev. No. 0 Survey, Design, Construction, Supply, Erection & Commissioning of Raw Water Intake Structure (Fixed type), Pump House on Intake structure Project Title including Pumping Machineries with all related Accessories, Raw Water Transmission Main for drawing 35 MGD Raw Water from The River Hooghly and Delivering to Water Treatment Plant on EPC Turnkey Basis Owner Superintending Engineer, Eastern Circle, Public Health Engineering Dte., Govt. of WB Design of Approach Jetty for Intake WAPCOS LIMITED (A Govt. of India Undertaking) Pump House (Habra Gaighata Intake Owner's Consultant Executing Agency Simplex Infrastructures Limited Consultanct to EA Projectscape Engineering Consultancy Services Private Limited Project) Name of Unit Structural Analysis & Design of Approach Jetty (Calculation of Scour Depth) Drawing Ref. Designed by: Shubhajit Barik Checked by: G Chakraborty Approved by: G Chakraborty Date: 9/6/2016 Reference CALCULATIONS CALCULATION OF SCOUR DEPTH BEYOND 40.0M HIGH BANK LINE W.R.T.HHWL (for1200Ø Pile) High Bank line has been considered (Refer Sketch No. PECS/SIL/1601/003/SK-01 as wetted line where HHWL merges with the River Bed profile near bank Max Discharge Velocity, V = 3.00 m/sec m ( Recommendation of KoPT as per Letter No. Hyd/ 12029/Jubilee bridge/PHED/1597) Discharge per M width of waterway (Db) =(A x V) = 15.41 cumecs Depth of Water considered for unit discharge from HHWL = 5.138 m (at centre of farthest pile nearly 40.0 m away from High Bank Line, 4.67m + 0.468m) So, Design Discharge per M width of waterway = 20.04 cumecs Increase of 30% over Design Discharge, as per clause No. 703.1.1 of IRC:78-2014, Catchment area less than 3000 km2 MEAN SCOUR DEPTH (dsm): As per IRC: 78-2014 the mean scour Depth below Hight Flood Level (HHWL) can be calculated theoritically from the following equation: dsm = 1.34 (Db /Ksf) 1/3 dsm= Mean depth of Scour Db = The design discharge for foundation per metre width of effective Waterway Ksf = Silt factor for a representative sample of bed material obtained uptothe level of anticipated deepest scour. Here, Mean Scour Depth, dsm= 4.298 m (From HHWL) Maxm Deoth of Scour from HHWL (2dsm)= 8.597 m ( As per clause No. 703.3.1.1 of IRC:78-2014) 2.a) Maxm Scour Depth From HHWL= 8.597 m (As calculated above) (The recommendation of KoPT as per Letter No. 2.b) Max Scour Depth From river Bed Level= m 8.400 m Hyd/ 12029/Jubilee bridge/PHED/1597 on Dated: Calculated Maxm Scour Depth From HHWL (8.400+5.138)= 13.538 m 11.12.2015 So, for Design purpose we would consider the Maximum Value = 13.538 m from HHWL Page 2 of 2