TECHNICAL PROPOSAL

BNPP DREDGING WORKS

Modelling CONSULTANCY ServicesTechnical and Commercial Proposal

ADEC/021/TCP/14/001 Rev.0May 2014

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REVISION RECORD

This cover page is a record of all revisions of the document identified above by number and title. All previous cover pages are hereby superseded and are to be destroyed.

Rev. No.DateByCheckedApprovalsDescription and Page Numbers of Revisions

013/05/2014MRKRMH1st Submission

Table of Contents1Introduction42objectives43Scope of works54REview and recommondation of data65Plume dispersion modelling65.1Hydrodynamic Modelling75.2Dredge Spill Dispersion Modelling76Exclusions87SCHEDULE88DELIVERABLES99ReferenceS9

LIST OF FIGURESFigure 1 Project Location4

IntroductionNMDC has contacted ADEC Consulting Engineers to study and recommend the safe distance required to avoid in impact of future dredging of cofferdam on the protection works being carried out recently by Hyundai Samsung joint Venture (HSJV). HSJV is currently placing a 500mm layer of rock revetment near the proposed dredging area, and NMDC has advised a minimum of 50m from the toe till the end of the revetment to avoid too much contamination during the dredging by sediment transport, the numerical modelling study sets as a base for the estimation of This Technical & Commercial Proposal has been prepared by ADEC Consulting Engineers in response to NMDC official inquiry by an email reference BNPP-Plume distance effect (Appendix A) to prepare a proposal for undertaking the required consultancy services. objectivesThe objective of the study is to investigate the safe distance required to avoid impact of future dredging of cofferdam on the protection works being carried out recently by HSJV.The following studies are required to be conducted: Dredge plume dispersion modelling

Figure 1 Project Location

Scope of worksTask 1: Dredge Plume Dispersion Modelling 1. Hydrodynamic modelling, provides basic conditions for Plume dispersion modelling2. Plume dispersion modelling: To investigate the recommended distance to avoid the impact of future dredging of cofferdam on the protection works.3. Report

REview and recommondation of dataReview of available data includes technical reports, bathymetry, previous study report near the project site and nearby marine projects, geotechnical data and survey results etc.The available data gives an insight to the project boundaries and limitations .The bathymetry survey provides the existing seabed levels at the location. The client will be advised for procuring/conducting the survey for any unavailable data required for the study.The data required for the numerical modelling study are: Bathymetry Data: Bathymetry is the key parameter for the numerical modelling, a high resolution bathymetry near the project site would give an accurate measure of results, for the areas outside project site and in the regional gulf models C-MAP bathymetry data will be used. Drawings: Information regarding the protection works and other information to be considered in the modelling works shall be provided by client in either electronic drawing format or ASCii data format to reflect them in the modelling. Geotechnical Data: Dredge plume dispersion study requires the Sieve analysis / grain size distribution profiles of the sediment to be dredged, these fractions will be made input to the model to assess the fate of plume dispersed or suspended in the water column or settled on the seabed. Dredging Plan or Activity: The client should provide the possible dredging and sediment spill rated due to the type of dredger/dredging activity is to be carried out. This includes but not restricted to dredging rate, spill rate, dredge track/location coordinates, dredging operational hours. Met-Ocean Data: (Optional) Availability of observational met-ocean data such as tides, currents and wind data near the project site will be useful for better calibration of model. Incase if there are no measurement available for the site, the model will be calibrated with Admiralty predicted tides from the nearest tidal station of project site.Plume dispersion modellingMIKE 21/3 Flow Model FM is a modelling system based on a flexible mesh approach. The modelling has been developed for applications within oceanographic, coastal and estuarine environments.ADECs plume dispersion modelling scope of work includes the following: Hydrodynamic modelling: To determine the normal flow conditions during different phases of tide, at the project site and provides hydrodynamic conditions for plume dispersion modelling. Dredge spill dispersion modelling: To investigate the safe distance required to avoid the impact of future dredging of cofferdam on the protection works being carried out recently by HSJV associated with the proposed BNPP site.Hydrodynamic ModellingThe Hydrodynamic Module is the basic computational component of the entire MIKE 21 Flow Model FM modelling system providing the hydrodynamic basis for the Transport Module, ECO Lab/Oil Spill Module, Mud Transport Module, Sand Transport Module and Particle Tracking Module.ADEC, will apply its existing calibrated and validated MIKE21 Flexible Mesh (FM) HD (DHI, 2012) flow model of the Arabian Sea to provide estimates of tide and wind driven water levels, as well as current speeds and directions throughout the area of interest. The model will be run in two-dimensional (depth averaged) mode and will provide the necessary boundary conditions for the local 2D hydrodynamic model. The model will be used to1. Define tide and wind driven currents at the project site ;2. Validate the local model with the available tidal and currents data (if provided by the client).3. Provide the basis for the 3D dredge plume dispersion modelling studies.Up to 4 conditions will be selected based on the tidal phase and available met-ocean conditions and initial runs. Each scenario will cover up a period long enough to ensure quasi stationary conditions are reached (the period to reach quasi stationary conditions normally varies between 15 and 30 days). Dredge Spill Dispersion ModellingADEC will also perform dredge plume dispersion modelling. Dredge plume modelling will investigate the fate of the dredge material during normal dredging operations of the proposed BNPP site, and will identify the safe distance for the revetment and also suggest the mitigation measures that should be considered by the contractor during dredging operations.Modelling will include 5% and 20% escape rates, which correspond to the contractor applying state of the art mitigation measures and no mitigations at all. The results will be compared against PIANC regulations for optimal dredging.A local 3D hydrodynamic model (MIKE 21/3 HD FM) is a multi-layered model used to derive the flow at various depth levels. The boundary data for the model will be extracted from the regional Arabian Sea model and will be set coupled with the MIKE 3 MT model. MIKE 3 MT -mud transport module (DHI, 2012d) calculates the resulting transport of cohesive materials based on the flow conditions found in the hydrodynamic calculations (MIKE 21/3 FM HD). The processes included in the Mud Transport module are kept as general as possible. The Mud Transport module includes the following processes: Multiple mud fractions Multiple bed layers Wave-current interaction Flocculation Hindered settling Inclusion of a sand fraction Transition of sediments between layers Simple morphological calculations The mud/ clay fractions are analysed during the Sieve analysis and the different fraction rations were considered and corresponding settling velocities were calculated and used in the model. The simulation considers different scenarios and will cover up to a period of 15 days to cover a tidal phase and attain quasi stationary condition. The Dredging operations will be considered for a period of 7 days and the plume fate will be assessed at the end of the 15 day simulation period. The simulation starts either from spring or neap phase of the tide to assess plume dispersion under 2 prominent conditions.The results of the simulations will be illustrated with the plots of Total Suspended Sediment Concentration (TSSC), Bed thickness change and Net accumulated deposition of the dredge spill in the domain. Exclusions 2D and 3D physical modelling Any environmental studies, approval or any related NOCs Surveys works, baseline, bathymetric geotechnical or any related soil sampling. Meetings with third parties other than ClientSCHEDULE

DELIVERABLESThe deliverables for this project includes consolidated results of both hydrodynamic modelling and dredge plume dispersion modelling in the form of a report.ReferenceSDHI. (2012). Hydrodynamic Module, User Guide. In MIKE 21 Flow Model FM (p. 120). Horsholm Denmark.DHI. (2012d). Mud Transport Module, User Guide. In MIKE 21 Flow Model FM (p. 62). Horsholm Denmark.