CEFAS24-144 RFQ for Bathymetry Surveys at Hinkley Point C

Tender description

Request for Quotation for Bathymetry Surveys at Hinkley Point C Background: The Hinkley BEEMS (British EDF Estuarine and Marine Studies) programme is funded by New Nuclear Build Generation Company (HPC) Ltd. Through this programme, Cefas provide authoritative scientific information on the marine and transitional waters in the vicinity of potential new build nuclear power stations and require a competent supplier to deliver the element described below. Requirement: Bathymetric surveys in the Severn Estuary are required to be completed during the construction phase of the Hinkley Point C (HPC) build programme. A total of two surveys are required in 2025. The supplier will undertake two multibeam echo sounder (MBES) bathymetric surveys. The first survey is expected between January to March 2025 which will serve as a pre-disposal for the placement of dredged material survey at the Portishead dredge disposal site (LU070) and King Road and Avonmouth Harbour Approaches area in the Severn Estuary, Somerset (see Figure 1). The second survey will be completed within two months of completion of initial capital dredge works (estimated September / October 2025). The bathymetric survey area covers the entire Kings Road and Avonmouth Approaches area, which encompasses the dredge disposal site LU070 (Portishead). With regard to the Portishead disposal site, data is officially required for the disposal area plus a 100m buffer of the Northern, Eastern, and Southern boundary and a 250m buffer on the Western boundary (Figure 1). Figure 1 shows that the Southern ‘buffer’ boundary runs parallel with the edge of the Southern boundary of the wider Kings Road and Avonmouth Approaches area. This Southern boundary skirts the intertidal zone but it is important to gather data here if safe to do so. Table 1 gives the bounding coordinates for the Kings Road and Avonmouth Approaches Area. Given the presence of fluid mud in the area (causing false bed heights during low energy periods), and the proximity of the Southern boundary to the intertidal zone, the survey must be undertaken during a period of Spring tides. As the two survey datasets will be directly compared with each other, and used for volumetric analysis, suppliers who commit the same vessel to both surveys would be more favourable. Cefas require the vessel(s), vessel crew, hydrographic survey team, and suitable equipment to undertake the surveys described. Cefas also require a lead hydrographic surveyor, with at least 5 years industry experience, to be present on the vessel(s) for the duration of each of the above surveys. Suppliers should also be aware that a client representative may join for part, or all, of the surveys. This will be confirmed within the pre-survey meeting. Cefas requires the supplier’s survey team to manage the planning (including access), notifications (including liaison with the Marine Coordination Centre (MCC) and Notice to Mariners), and safe execution of the surveys. Should licences or consents be required (e.g. a Marine Licence) these will be obtained by Cefas and provided to the supplier’s survey team prior to the survey. Positioning equipment: For all surveys, horizontal control (with a minimum accuracy of 0.25m or less) should be achieved by using a Real Time Kinetic (RTK) Global Navigation Satellite System (GNSS) (either dual antenna or incorporating a gyro compass to provide heading solutions) with real time corrections supplied via continuous connection to a RTK correction service. The survey spread shall also include a fully integrated Inertial Measurement Unit (IMU). Preference will be given to more modern systems. Full verification of the Generalised Admiralty Model Service (GAMS) and GNSS positioning must be undertaken as part of mobilisation, and the results shared with Cefas before survey operations commence. Depth sounding equipment: For all surveys, vertical control (bathymetric data) shall be acquired using an appropriate MBES system which is capable of delivering a minimum of 10 hits per m2. The MBES shall be equipped with Sound Velocity measurement at the transducer head and integrated with an inertial measurement unit and configured such that all offsets/lever arms in the survey spread are properly accounted for. All depths should be reduced to Ordnance Datum Newlyn (ODN). Whilst Cefas is open to suggestion as to the system to be used, preference will be given to multifrequency / multispectral acquisition platforms. A patch test will be performed at mobilisation together with all appropriate verification checks required to demonstrate that required survey accuracy is met. Furthermore, Cefas is also willing to consider use of interferometric systems such as the Edgetech 6205. MBES Backscatter data is to be acquired for all survey extents. Efforts shall be directed to ensuring that the MBES settings (power, gain and pulse length) are optimised to produce consistency in the backscatter dataset collected. Sound Velocity Profiles (SVPs): Cefas expect SVP data to be acquired ‘as required’ during survey operations (i.e. with a new SVP collected at the start of day’s days operations and on each occasion that the Sound Velocity (SV) measured at the transducer head deviates by more than 2m/s from the near surface SV obtained from the most recent SVP). As such, Cefas expect multiple SVP to be collected during MBES operations. Cefas anticipate SVP deployments will be made during spring tides to capture variations in the SV profile over the water column at peak ebb and peak flood as a minimum. Online / survey acquisition and processing software: Cefas do not require any specific navigation / MBES acquisition packages to be used, however expect those proposed to be from industry standard developers (e.g. Qinsy, Hypack, SIS or Beamworx). The survey navigation package shall provide the means of continuously monitoring the performance of the survey spread and the instruments within it, as well as the quality of data being captured throughout each day of survey operations. Any variations in configuration or performance of the survey spread, as well as factors impacting on the quality of data acquired, shall be recorded in the surveyor’s online logs which will form part of the deliverables for the survey. Survey reporting shall provide details of the processing workflow applied to the data including any compensation/adjustments made to the data which may be applied either online or offline as part of the post processing of acquired data. The supplier shall provide details of their proposed survey system together with the hit count and other appropriate quality metrics (Total Vertical Uncertainty, Total Horizontal Uncertainty) indicating the accuracies they expect to achieve in the nearshore and offshore survey areas, and shall anticipate inclusion of such quality metrics in the survey deliverables with a discussion of the survey accuracy achieved provided as part of survey reporting. Data standard: The data must comply with the International Hydrographic Organization (IHO) s-44 Special Order, edition 6.1.0 (IHO, 2022) as outlined in Table 2 above. This standard specifies Total Horizontal Uncertainty (THU) horizontal accuracy of 2m and Total Vertical Uncertainty (TVU) of 0.25m plus 0.0075% of water depth. A proposed line plan should be supplied that will meet the requirement of 100% in sonification of the survey area. With an overlap of at least 15% between adjacent swathes. A suitable number of cross lines are required. Data is to be reduced vertically to ODN using or Chart Datum (CD) by utilising the Vertical Offshore Reference Frame (VORF) model and shall either be a RTK or post-processed methodology. Processed raster, vector and charting products are to be produced using the Ordnance Survey OSTN15 / OSGM15 transformation models. Where possible, this information shall be embedded into any digital file formats or provided with a suitable ESRI ArcMap projection (.prj) file. Weather and equipment downtime: The supplier should include an indication of the vessel(s) weather limits and provide for a reasonable “Day rate for weather downtime or client standby for vessel and crew” and separate “Day rate for weather downtime or client standby for vessel only (if applicable)”. It is expected these bathymetric survey’s will be completed over a Spring-tide window, and it is the responsibility of the supplier to schedule the survey to meet forecast and predicted weather and tidal conditions, confirming these with Cefas. Costs supplied should include any charges payable by Cefas in the event of poor weather affecting operations or in the event that client standby is required. The expectation is that the survey campaigns will vary in duration. Preference will be given to responses which emphasise flexibility in mobilisation to achieve the highest data quality; for example, adapting each survey where required (e.g. into two phases due to weather) to ensure the highest possible data quality. Any permission to accrue weather downtime costs given must be in writing or by email from Cefas to the supplier. Any charges for weather downtime where no evidence of prior approval exists will not be approved and will not be reimbursed. Communications: Daily Progress Reports (DPRs) alongside representative screenshots of raw/ unprocessed data, are to be sent to the Cefas representative via email at the end of each survey day from commencement of the survey work. These progress reports should detail any weather or equipment related down-time, plus any incidents or near misses. Quality control: The supplier’s survey team will be expected to inspect the bathymetric data in the field or immediately after (at the end of each working day) to ensure that high quality data are acquired. It is expected that where weather conditions or equipment malfunction result in compromised data (i.e.>10m along track / line keeping error) the affected lines will be “re-run”. Cefas have the right to request re-runs after review of the data presented along with the DPRs. The supplier shall ensure integrity of data at all times, on a system that is secure and regularly backed up. Acquired imagery and metadata are to be delivered to Cefas (Lowestoft) on completion of the survey work via an encrypted hard drive or a shared server space which will be made available for data delivery by Cefas. Health and Safety: A Risk Assessment and Method Statement (RAMS) document will be required, which will require sign off from Cefas and NNB Generation Company (HPC) Limited prior to the survey. Typical review periods are around two weeks, therefore RAMS should be made available at least two weeks before the planned survey date. Cefas will provide a template for the supplier to complete if required. It is expected that the supplier complies with the review and administrative processes imposed by Cefas and NNB Generation Company (HPC) Limited. Please note there may be several rounds of review and update required prior to sign off. A completed Vessel Safety Assessment and Inspection Document (VSAID) and vessel inspection will be required prior to survey commencement; a copy of which is included in the Bidder Pack for information, please note this can take up to one month to complete. This may not be required if the vessel has an in date CMID inspection. Cefas requires that the vessel and the crew are able to undertake the contracted activity in the stated waters, in line with the requirements of the Maritime and Coastguard Agency (MCA). This relates to having suitable vessel registration and licencing plus vessel owners’ standards for complying with regulations on crew competency (including survival at sea) and their meeting of medical standards plus current training to support first aid in the event of an accident. Suitable lifesaving equipment is to be on board, suitably maintained and worn in line with maritime best practice Please see RFQ Part 1 Technical document included in the Bidder Pack for full list of deliverables