Method Statements For Shore Protection And Temporary Unloading Ramp

Method Statements For Shore Protection And Temporary Unloading Ramp_Method Statements for Method Statements For General Concrete Work Works and to details out the steps to be taken in meeting the technical requirements of Van Phong 1 thermal power plant project

Comment Response Sheet (CRS) Project Title Van Phong BOT Thermal Power Plant Project Document Title METHOD STATEMENTS FOR SHORE PROTECTION AND TEMPORARY UNLOADING RAMP Document No Document Type For Approval Returned Status AC Prepared by CRS Issued Date 19/02/2020 Engineer Construction Review Date Status O/C * Remarks 04/02/2020 O 19/02/2020 C 04/02/2020 O 19/02/2020 C ET Kim VP1-0-L4-C-GEN-10006 VP1-0-L4-C-GEN-10006-D-CRS CRS No No Section/ Page Owner’s Comment List documents with reference number The document with the reference number listed cannot be found Response to Comment DHI has been mention on MS (Rev D) and the Design document list for shore protection and Unloading Ramp will be submit separate document – Section I.3.1 The preparation for shore protection & unloading ramp should including site office, fabrication yard, stock yard for pre-cast block, heavy equipment parking area, rebar shop, maintenance shop, waste area and temporary access from yard to installation place and temporary jetty (if any) The general layout plant should be provided, indicate the location, necessary dimension and capacity, structure of those temporary facility Open See comment on page DHI h as r evised an d up d at ed o n MS (Rev D) in At t ach ed #06 Page of 13 Comment Response Sheet (CRS) - These BM was installed long time ago This data come from where? Who is the third party? - A new BM system shall be re-built for constructing permanence structure and to be used for all Lots - The controlling and calibration of project benchmarks should be stated Open, shore protection is not only stone works but also concrete works which show the finishing boundary line, please consider this is a permanent and exposed structure 04/02/2020 O 19/02/2020 C 04/02/2020 O 19/02/2020 C 04/02/2020 O DHI has mention on MS (Rev D)- Section 5.7.7 19/02/2020 C DHI has been done on MS (Rev D) 04/02/2020 O 19/02/2020 C The contractor has been mention clearly on MS (Rev D)- Section III.2 19/02/2020 Noted The temporary benchmarks should be set up during the construction and inspection stage The said plan should incorporate in this clause Open If so, kindly submit the survey plan, including survey monitoring plan separately for review and approval Provide calculation/ information when the blocks are enough required strength to remove bottom formwork and transportation Open the Contractor has not provided calculation yet The contractor has been mention clearly on MS (Rev D)Section III.2 Cover Mark clearly in the document parts that were revised, added or deleted between revisions This has not been done!! It is very time consuming to check a new revision if changes are not marked In the next revision mark clearly all revisions from A to B, B to C and any new ones from C to D Mark them clearly with the corresponding revision number (B, C, or D) 19/02/2020 Closed It would have been helpful to show changes from previous revisions as well Page of 13 Comment Response Sheet (CRS) Cover (2) DHI is strongly recommended to consider the settlement monitor works for ground settlement and settlement/movement of coffer dam itself during construction and operation of project If YES please show the detail arrangement and method (2) Not accepted settlement monitoring works to be shown in this method statement DHI has been mention and updated on MS (Rev D) (Section 5.4) 04/02/2020 O 19/02/2020 O 04/02/2020 O 19/02/2020 C 04/02/2020 O 19/02/2020 C 04/02/2020 O 19/02/2020 C 19/06/2020 DHI has explained with owner/consultant that under water Cover Cover 19/02/2020 (2): Arrangement not agreed In case of monitor the settlement, it is common practice to carry out the monitoring at elsewhere ground elevation in order to evaluate the settlement and stability during construction period, which is compared with design calculation Based on this record, timely propose solution/method statement if necessary and while dumping stone for core rock the settlement plate is impossible to installation/monitoring, monitoring the settlement will be conducted above water level from top of core rock layer, it has got approved with ITP also (3) Content changed or modified should be revision cloud mark (3) Not done This requirement help to check the changed content quickly DHI has been done on MS (Rev D) 19/02/2020 (3) Closed Natural condition Update the latest data and unify the data in project The Contractor has not updated to MS Rev.C 2.1 This information is only for reference to proceed site work and referred from Met-ocean survey report Check the rainy season data from April to May? The Contractor has not replied yet 10 Figure General plan (P6) DHI has revised and updated on MS (Rev D) (Section I.2.1) DHI to provide the information of this structure Open, Please see comment on page DHI to provide the plan on new benchmark system for Shore Protection & U-ramp such as: location, number, distance, DHI has mention and updated on MS (Rev D) (Section 5.10) The contractor has been mention clearly on MS (Rev D)Section III.2 If so, please stated it inside this MS, page 10 Page of 13 Comment Response Sheet (CRS) 11 (P11) The number of excavator is not enough and DHI to clarify why no use excavator from Apr to Sep, even rock work is continuing until Oct Why trailer no need for transportation blocks during installation? The quantity should be considered Consider lifting work for transportation to site The suitable capacity of flat barge should be considered, to have stable working condition, and placing work can be done accurately why no crane barge for blocks installation mentioned in this table? Why no need dump truck during rock work? the number should be clarified According to your schedule, the average 670 m3/day rock materials should be provided by sea side It means barges is not enough to provide this quantity per day More detail information about capacity DHI has been consider and has plan to mobilize more equipment when necessary 04/02/2020 O DHI has revised and updated on Rev D (section III.3) 19/02/2020 C 04/02/2020 O 19/02/2020 C DHI has revised and updated on Rev D (section III.3) DHI has revised and updated on Rev D (section III.3) DHI has calculated with 02 barge (capacity about 1000T) is enough for transportation rock material In addition, stone can be delivered to sea side through temporary jetty Open The Contractor has not considered comments 12 V SHORE PROTECTION CONSTRUCTION 5.1 (P15) 5.1 (P15) - The sequence of work in sector L3 is shown as attached figure - Based on that sample, DHI should make similar to other Sector, and reflect to below chart (should be more detail) - For sector which done by marine work, please show separately off-shore work and on-shore work (elevation? what layer?) Open The Contractor has not considered comments It related to inspection on site, should make clear on this MS Seq uen ce o f w o r k alr ead y h as b een in clud ed o n MS an d w o r k m et h o d in sect o r 2,3,4,5 is sam e excep t d um p in g co r e lo ck f r o m t h e b ar ge f o r L3 Please f in d MS –Section 5.1, with drawing & ITP Inspection elevation has been explained on the interface check meeting with VPCL and detail elevation and location for inspection will be discussed with the Owner/Owner’s engineer when performance on site It conflicts with description in below chapter (offshore work for L5, L4, L3, L2-1) Open See comment on page 23 DHI has revised and updated on Rev D (section 5.6.1) Page of 13 Comment Response Sheet (CRS) 13 (P15) 5.2 (P16) (P16) Before start the work (from team 1) the temp work such as stone stock yard, temp access, temp yard should be done first Open Not updated yet Current design, L1, L6, L7 structure sector is different with another segment; therefore, it should be described separately Temporary work has been mention on attached #06, and all 04/02/2020 O 19/02/2020 C Met h o d st at em en t s can n o t co n t ain all in f o r m at io n DHI w ill 04/02/2020 O co n d uct t h e w o r k un d er h is r esp o n sib ilit y as EPC 19/02/2020 O temp access for work will be use current existing road Structure of structure L1, L6 and L7 are same so sequence of work is same Cannot find in the MS Drawings at page 16, 17 need to be updated in final approved design drawing DHI has updated drawings at page 16, 17 as same with design drawing submission Cannot find in the MS (P18) Provide execution method at each interface area Cannot find in the MS 14 5.5.1 (P22) The levelling work should be described detail in this MS (so far it does not show any levelling work in detail) Safety matter when combine diver and excavator also shall be clarified Communication method, safety control, how to combine action of diver and equipment when leveling big stone size We are still not convinced yet Similar comment on page 24 At least the Contractor should describe leveling under water by diver combine excavator as stated in MS 15 Figure 12 (P24) 19/02/2020 There is nothing improve from Rev.C, or no additional information regarding leveling work under water Please provide basis or calculation of this value, in order to remove bottom formwork Also provide the lifting method for review and approval in this MS We are still not convinced yet Similar comment on page 28 The interface check meeting with VPCL an d b een co n d uct ed o n Feb In t er f ace ar ea/co n n ect io n ar ea w ill b e d o n e b ase o n d esign af t er d r aw in g d iscussio n w it h r elat ed su b co n t r act o r s co n t r act o r , h o w ever DHI h as d escr ib ed o n MS (Rev D) (Sect io n 5.6) 19/06/2020 DHI has mention and updated on MS rev E (section 5.6) Met h o d st at em en t s can n o t co n t ain all in f o r m at io n DHI w ill co n d uct t h e w o r k un d er h is r esp o n sib i lit y as EPC co n t r act o r , h o w ever DHI h as at t ach ed t ech n ical guid in g f r o m Ko gaku (r akun a co n t r act o r ) in at t ach ed #2 Closed 04/02/2020 O 19/02/2020 C Page of 13 Comment Response Sheet (CRS) 16 6.6 (P34) 17 8.1.8.9 (P42) Provide stability check during block installation: when crane and trailer, blocks come together Not agree, it should be shown in the MS, please see comment on page 35 19/02/2020 Closed However, please describe clearly your sequence of setting crane for installation of concrete block to avoid slope sliding in Section 6,6 This is not response plan, this table only shows information, there is no response plan We are still not convinced if the Contractor prepare during execution stage, in case accident happen, how to response? Met h o d st at em en t s can n o t co n t ain all in f o r m at io n DHI w ill co n d uct t h e w o r k un d er h is r esp o n sib ili t y as EPC co n t r act o r Ho w ever , DHI has described on MS (Rev D) (Section V.5.8) and all safety execution will be complying with HSE detail manual for L4: VP1-0-L4-H-GEN-00003 04/02/2020 O 19/02/2020 C Closed 04/02/2020 O 19/02/2020 C DHI has revised and updated on MS (Rev D) (Section 8.1.9) 19/02/2020 Closed The response plan still need to be updated and provide sufficient information of contact number, person in charge 18 Progress S-Curve for Shore Protection Provide information in summary items (shore protection, and each sector) such as: q'ty, start, finish date, duration Closed DHI has described on MS (Rev D)-attached #01 If so, please change the chapter name and attachment name 04/02/2020 O 19/02/2020 C 04/02/2020 O 19/02/2020 C (P42) 19 Content (P2/51) Missing 5.2 DHI has corrected on MS (Rev D)- page Numbering is not correct DHI has corrected on MS (Rev D)- page Page of 13 Comment Response Sheet (CRS) 20 General (P3/51) 21 2.3.1 (P5/51) III (P9/51) Table 2.3 The temporary jetty is mentioned in this paragraph, figure & figure However, no drawing, no calculation or no construction method, no schedule stated on this MS DHI has updated on MS (Rev D) (Section 5.10) 19/06/2020 19/02/2020 Open Add parameters on Cross-Sections; Primary calculation on Stability of Gabion in operation condition; location on plan drawing kindly add relevant water level such as: Mean Sea Water Level… DHI has revised and updated on MS Rev.E (Section 5.10) In design drawings of Shore protection, WL = +1.910mÐWL = -0.980m Why are they different DHI has corrected on MS (Rev D) (Section I.2.3) Please attach the drawings of temporary facilities as attachment DHI has revised and updated on MS (Rev D)- Attached #06 Please update latest design if any Quantity on MS is on the newest drawing version table name from 2.5 to 2.8 please re-arrange DHI has revised and updated on MS (Rev D) 04/02/2020 O 19/02/2020 Closed O 04/02/2020 O 19/02/2020 C DHI has revised and updated on MS (Rev D) (Section I.2.3) (P10/51) Table 2.5 (P11/51) Page of 13 Comment Response Sheet (CRS) 22 V (P16/51) (P16/51) 5.3 (P17/51) After initial sections of Chapter V, as mentioned in Figure the sequence of work, in order to make MS's contents easy to understand, it should be separated into parts: -Part 1: described for sectors L1, L6, L7; -Part 2: described in sectors L2, L3, L4 and L5 (Because there are two different structures of shore protection construction) Noted, in order to avoid any lack of any information due to combination DHI will keep mention like this Re-check the applicable construction method In our opinion, installing core rock should be performed onshore Noted, DHI has corrected on MS (Rev D)- Section 5.1 There is a conflict with Figure Diagram of sequence of Shore protection construction DHI has corrected on MS (Rev D)- Section 5.1; 5.2 04/02/2020 O 19/02/2020 C Open, See comment at page 17 Figure (P19/51) (P21/51) Please show the stockpile area (location) for each construction direction There is only this quarry transport by marine method, and the capacity is limitted We understand that this quarry is mainly for sector L3 Please note that, quarry will supply not only for DHI, other customer also In case this quarry is over mining capacity (over 120,000 m3/year) or over supply capacity (not enough equipment, manpower, ), the Contractor should prepare back-up plan such as alternative quarry which can transport by marine, or temporary jetty to load rock materials to barge Currently we have plan for stock pile area for stone to cope with any shortage of delivery However, based on the progress of site leveling work, the Contractor will discuss with the Owner for this issue later, if required additional area Well Note, DHI did not only use this quarry but also additional quarry is available, also temporary jetty is considered to make sure amount stone’s delivery for marine work 5.6.1 (P23/51) Please confirm the offshore construction method for section L2-1? DHI has revised and updated on MS (Rev D) (Section V.5.6.1) Figure 11 (P24/51) Figure 13 (P25/51) (P25/51) Safety caution should be provide when vehicles and equipment operate on the top of rock mount (minimum safe distance to the slope) and diver's activities when the crane barge is under construction Please refer to previous comment for more detail DHI will provide Safety caution at site when start working Kindly confirm with Kogagu about the acceptance of removal of the Rakuna block’s bottom formwork and transport to stock yard when the minimum concrete strength is 5MPa! In our opinion, this criteria (5Mpa to remove bottom form and transport) shall affect quality of Rakuna Block! DHI has confirmed with Kogaku, refer to Attached #2 According to figure 6, installation of precast concrete component is onshore work, if so it should be removed Installation of precast concrete component is on-shore and off-shore work DHI has corrected on MS (Rev D) Page of 13 Comment Response Sheet (CRS) Kindly confirm with Kogagu about the acceptance of removal of the Rakuna block’s bottom formwork and transport to stock yard when the minimum concrete strength is 5MPa! DHI has confirmed with Kogaku, refer to Attached #2 According to clause 5.1 Sequence of the construction, onshore method shall be applied for precast components (Rakuna, stone block) Therefore, these components are transported to barge at temporary jetty is unnecessary DHI has revised and updated on MS (Rev D) (Section 5.8) DHI confirmed that it is on-shore and off-shore works (P30/51) According to clause 5.1 Sequence of the construction, onshore method shall be applied for precast components (Rakuna, stone block) Therefore, these components are transported to barge at temporary jetty is unnecessary 5.9 During re-bar arrangement and formwork, Nylon may be damaged by base stone Lean concrete is better Noted, DHI will monitor during work if Nylon is damaged during rebar and formwork installation, lean concrete will be replaced Review and revise the dimension of stone that is being incorrect with new & updated design version DHI has revised and updated on MS (Rev D) (Section 6.1) HWL=1.91m and this is only 0.09m higher Small waves can climb on dyke Higher is better Considering that this is temporary work, it has been considered only for actual short working period Based on tide table of 2020 published by center for oceanography, from Feb to July expected high water level is 0.5m only, also wave is mild on dry season (P32/51) That pumps water or reduces water level in the foundation for temp unloading ramp is very important The contractor need to calculate the amount of flow moving into foundation hole in order to carry out the feasibility method Provide the calculation of penetrated water flow and number & capacity of pump equipment DHI has revised and updated on MS (Rev D) (Section 6.2) and in Attached 06 Figure 24 From seaside, 1m width of stone ~Geotextile ~ Clay layer ~ 2m width of Stone dyke is better to prevent erosion and seepage (P28/51) 23 5.8 (P28/51) Figure 19 (P30/51) 6.1 04/02/2020 O 19/02/2020 C (P31/51) 6.2 (P32/51) (P32/51) (P32/51) 6.3 (P33/51) DHI designed: from seaside 3m width of stone ~nylon/geotextile ~ 2m width clay soil, total top width of dyke is 5m The cross-sectional structure of Temporary Dyke as shown in Figure 25, is it feasible to prevent the water flow through the temp dyke body when the maximum water level in front of the dyke is about 2.0 m? Based on tide table of 2020 published by center for oceanography, from Feb to July expected high water level is 0.5m only, also wave is mild on dry season Disposal of pumped up water should be stated Water will pump to existing aqua farm, and DHI has revised and updated on MS (Rev D) (Section 6.3) Page of 13 Comment Response Sheet (CRS) 24 6.3 (P33/51) Figure 26 (P33/51) Seepage volume of groundwater should be calculated with number/capacity of pump If crane access is not saved, the countermeasure for dewatering should be considered This statement should be written in MS Please refer to Attachment 05, and during construction time DHI will monitor and has countermeasure immediately if some happened Contractor need to provide the calculation and clarify the feasibility of maintaining the expected water level during construction period There is a big change from onshore construction in MS Rev A & B to offshore construction in MS Rev C Contractor is required to carefully check quality of underwater work such as foundation excavation, bedrock compaction and concrete block installation DHI shall calculate and arrange suitable pump before execution- Attachment 05 Using divers DHI has revised and updated on MS (Rev D) (Section VI.6.5) Please write down the numerical tolerance DHI has revised and updated on MS (Rev D) (Section VI.6.5) From experience, underwater (7m depth) work can be barely done by divers but safety/quality of work may be much less than dry work Unloading ramp is only temporary use, but the quality of structure should be solid and durable Well note, all will be control carefully Please specify compressive strength of concrete or curing period DHI has revised and updated on MS (Rev D) (Section 6.6) Contractor need to specify the safety distance of crane standing on slope and capacity of crane, working radius for concrete block installation of temp unloading ramp On the other hand, in the plan at figure 24, there is not enough space for crane and trailer after making open ditch All safety matter will be complied with HSE manual detail for L4: VP1-0-L4-H-GEN-00003, and please refer to table 2.8 for crane information How much thickness ? DHI has revised and updated on MS (Rev D) (Section 6.7) Is this : ? Yes, DHI has corrected information Organization chart of safety department Responsibility of each position DHI has corrected contain, organization chart has been mention on section Provide detailed internal safety plan DHI will comply with HSE detail manuals for L4(Vp1-0-L4-H- 04/02/2020 O 19/02/2020 C Well note and DHI will check it carefully during while working 6.5 (P34/51) Figure 28 (P34/51) 6.6 (P34/51) Figure 29 (P35/51) 6.7 (P35/51) VIII (P39/51) 8.1.2 (P39/51) 8.1.3 (P39/51) 8.1.5 (P40/51) Must be inspected daily, weekly and monthly (The Contractor should have internal inspection checklist) " Work under water " should be stated GEN-00003) DHI has revised and updated on MS (Rev D) (Section 8.1.3) DHI has revised and updated on MS (Rev D) (Section 8.1.6) Page 10 of 13 VAN PHONG BOT THERMAL POWER PLANT PROJECT ATTACHMENT 05: CALCULATION OF WATER ABSORBENT P a g e | 57 CALCULATION FOR WATER ABSORTENT TO FOUNDATION PIT OF TEMPORARY UNLOADING RAMP + Calculate the amount of water that penetrates to the foundation pit with high water level: +1.91m + Absorbent area of existing ground: soil layer 3-Clay sand with gravel: F1 = 3896.45 m2 + Absorbent coefficient of soil layer 3-Clay sand with gravel: K1 = 5x10-7m/s Reference to “Swiss Standard SN 670 010b, Characteristic Coefficients of soils, Association of Swiss Road and Traffic Engineers” + Absorbent area of existing ground: soil layer 6A-Coral rock: F2 = 2760.84 m2 + Absorbent coefficient of soil layer 6A-Coral rock: K2 = 4x10-6m/s Reference to:  Carter, M and Bentley, S (1991) Correlations of soil properties Penetech Press Publishers, London  Leonards G A Ed 1962, Foundation ENgineering McGraw Hill Book Company  Dysli M and Steiner W., 2011, Correlations in soil mechanics, PPUR + Absorbent area of filling soil of temporary dyke - Clay sand: F3 = 1342.35 m2 + Absorbent coefficient of filling soil - Clay sand: K3 = 5.5x10-9m/s Reference to:  Swiss Standard SN 670 010b, Characteristic Coefficients of soils, Association of Swiss Road and Traffic Engineers  West, T.R., 1995 Geology applied to engineering Prentice Hall, 560 pp + Due to formular (2) of TCVN 8731:2012 Absorbent coefficient: K = Q/F Where: K - Absorbent coefficient Q - Absorbent quantity F - Absorbent area  Absorbent quantity: Q = KxF + We have Absorbent quantity in to foundation pit of Temporary Unloading Ramp: Q = K1xF1 + K2xF2 + K3xF3 = 5x10-7x3896.45 + 4x10-6x2760.84 + 5.5x10-9x1342.35 = 0.013(m3/s) = 46.8 (m3/h) + Pump choice With the pump height is 9.1m, the pump length is about 45m (1m pump height is similar to 10m pump length) so total of pump height is 9.1 + 4.5 = 14.6m We choose type of pump with frequency 50Hz and curve No 3, free standing as below table: According to relationship chart between the height of water pumping and quantity of pumping as below: With the height of water pump is 17m we have quantity of pump is (m3/min) ~ 240 (m3/h) so we choose 01 pumps Tsurumi 250B622 (or other with similar capacity) Free standing Pump After finishing temporary dyke the contractor shall test absorbent quantity to verify the calculation VAN PHONG BOT THERMAL POWER PLANT PROJECT ATTACHMENT 06: PLAN OF FACILITY AREA P a g e | 58 VAN PHONG BOT THERMAL POWER PLANT PROJECT ATTACHMENT 07: CALCULATION FOR TEMPORARY JETTY P a g e | 59 CALCULATION STABILITY FOR TEMPORARY JETTY I Major external loads: Calculation for the most dangerous case when the water level is low : LWL = -0.98 (NDT) Soil Investigation Report of Bore hole BHO-2 - Layer 2: Loose, whitish grey, Sand with quartz gravel Model: Model Mohr-Coulomb Unit Weight 18.2 kN/m³ Cohesion 3.4 kPa Phi 28o - Layer 6B: Highly weathered rock zone IA2, blue grey Model Mohr-Coulomb Unit Weight 16.1 kN/m³ Cohesion 41.2 kPa Phi 15°15’ - Layer 5: Clay with Weathered rocks Model Mohr-Coulomb Unit Weight 19.5 kN/m³ Cohesion 41.2 kPa Phi 15°57’ - Back fill Model Mohr-Coulomb Unit Weight 18.0kN/m³ Cohesion 0.0 kPa Phi 28° - Core Rock Model Mohr-Coulomb Unit Weight 20.0kN/m³ Cohesion 0.0 kPa Phi 42° Live load The most dangerous case is to use a 250T crane as show Trailer Load Data for Crane 250T (9 axcels) Item Load A Load weight 380.0T B Beam weight 15.0T C Trailer weight 90.0T D Total weight A+B+C 485.0T E Load/axcel D : Axcels 53.9T F Load/Tire E : Tires 6.7T G Pressure Area (12.0x6.3)m 75.6 m2 H Ground Pressure D:G 6.42T/m2 - Uniformly distributed surcharge: 6.42 T/m2 - II Method: Bishop Calculation stability for vertical jetty: Sliding arcs diagrams: Figure Circular Slip of vertical jetty Conclution: According to work analysis of softwave GeoStudio 2012 (SLOPE/W), Stability coefficient of inclined temporary jetty is 1.394 > 1.0 so structure of vertical temporary jetty match requirements VAN PHONG BOT THERMAL POWER PLANT PROJECT ATTACHMENT 08: DETAIL DRAWING PRECAST FOR COPING LAYER P a g e | 60