ENVIRONMENTAL STATEMENT BARDOLINO DEVELOPMENT

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Bardolino Development Environmental Statement 6.2 THE PHYSICAL PRESENCE OF THE DRILLING RIG AND SUPPORT VESSELS (INCLUDING ANCHORING OF THE DRILLING RIG) 6.2.1 Likely magnitude and duration Shell proposes to drill the Bardolino development well with Transocean’s semi-submersible drilling rig, the Arctic IV. The presence of the semi-submersible rig and support vessels during the drilling operations might result in some interference with commercial fishing or shipping in the area adjacent to the Bardolino location. A temporary safety exclusion zone with a radius of 500m centred on the semi-submersible drilling rig would be established for the duration of drilling operations, a period of 3 months. This would exclude commercial and fishing vessels from an area of approximately 0.8 km 2 . The semi-submersible drilling rig would be positioned over the drilling location with the aid of the three AHTVs, and would maintain its station by eight anchors in a pre-determined ‘anchor pattern’. In such a system, the anchors are attached to the drilling rig with a chain and cable combination; for each anchor line approximately 300m of chain would be in contact with the seabed, providing additional holding power. The use of anchors to position and moor the semi-submersible drilling rig would result in the physical disturbance of seabed sediments and benthic fauna in localised areas around the anchors (chains and wires) during deployment and retrieval. Depending on the nature of the seabed, anchors can create mounds up to 1 m high, and anchor chains lying on, and sweeping over, the sediments can create gouges and scour marks. Anchor mounds can form on clayey sediments, and because of the stiffness of clay they have the potential to become long-lived seabed features that may represent obstructions to mobile fishing gear deployed on the seabed. The anchoring conditions survey undertaken for the Bardolino well location indicated that seabed sediments comprise a veneer of sand with outcrops of clay (Gardline Geosurvey Limited, 2007). The shallow soils comprise soft to firm slightly sandy clay with occasional gravel, ranging from 25 m thickness in the west to being locally absent in the east (Gardline Geosurvey Limited, 2007). It is possible that persistent anchor mounds would be created on this type of sandy clay sediment. 6.2.2 Impact on sensitive receptors and proposed or designated sites The presence of the semi-submersible drilling rig at the Bardolino location would result in a temporary loss of access to fishing grounds and a temporary inconvenience to commercial shipping in the area. The overall relative value of fisheries in the Bardolino development area is classified as “very low” to “low” for ICES rectangles 44F1 and 43F1 (SEERAD, 2008b) (Section 4.5.1). The relative fishing effort for demersal species, pelagic species, Nephrops and shrimp and shellfish is “very low” (SEERAD, 2008b). Demersal pair and otter trawling has dominated fishing effort in the Bardolino area between 2002 and 2006, with fishing activity occurring throughout the year (Section 4.5.1). The potential disturbance to commercial fishing from the drilling programme would be of a small-scale and would be very unlikely to impact on the economic value of the overall fishing activity in this area. The timing and nature of operations would be notified to other users of the sea and a dedicated guard vessel would be on location at Bardolino to ensure that all traffic was aware of the presence of the drilling rig. The distribution and abundance of benthic organisms in the North Sea is determined largely by latitude, water depth and sediment type. Results from biological surveys carried out in the general vicinity of the Bardolino development show that the infauna is typically dominated by polychaete worms, while epibenthic species include the shrimp Crangon allmanni and the hermit crab Anapagurus laevis (Section 4.4.2). The macrofaunal communities of the proposed development area are largely homogenous and typical of sandy sediments in the central North Sea. No sensitive, rare or threatened benthic communities are known to exist in the vicinity of Bardolino. Anchor mounds and scours have the potential to cause disruption to benthic communities. The deployment and retrieval of anchors from the semi-submersible drilling rig would cause Page 6-2 April 2008
Bardolino Development Environmental Statement some direct impact on invertebrates living on and in the sediments, and such disturbance would occur within a relatively small area of seabed defined by the extent of the anchor pattern (approximately 1 km 2 ). This disturbance, however, will be small in comparison to the seabed disturbances already created by the fish trawling activities occurring with the area. Benthic communities in the development area are similar to those found throughout the surrounding area of the central North Sea and no rare species are known to occur in this area. The drilling rig would be anchored to the seabed for about 3 months, and the area of seabed that would be directly physically affected will be very small. If fish were to be displaced by the anchoring activities this would be temporary, and fish would be expected to rapidly return to the area once the initial installation of the semi-submersible drilling rig had been completed. The proposed drilling location coincides with spawning areas for mackerel, lemon sole, Norway pout and Nephrops. Spawning and nursery areas are widely dispersed across the North Sea, and the spawning and nursery phases for most fish species are dynamic features of their life history, which shift and change in accordance with prevailing temperatures and prey availability. Consequently, spawning and nursery grounds are rarely fixed in the same location from one year to the next (CEFAS, 2001). As a result, it is considered that the localised effects associated with the installation and presence of the drilling rig would not have a significant impact on fish spawning or nursery areas. The drilling period would last approximately 3 months, and during this time there would be restrictions on commercial shipping and fishing in the immediate area of the rig. These are not considered to be significant, however, because the restrictions would be short-term, fishing effort in the area (Section 4.5.1) is very low, and shipping activity in the area (Section 4.5.2) is moderate overall for this area of the central North Sea. 6.2.3 Contribution to transboundary, cumulative or global impacts The presence of the drilling rig would cause temporary inconvenience to commercial fishing and shipping. Fishing activity is regulated by quota, and the loss of access to fish in this small area would not significantly reduce the ability of fishermen to achieve their quotas, given the large area of available fishing grounds in the rest of ICES rectangles 44F1 and 43F1. The presence of the drilling rig would therefore not represent a cumulative impact on fishing or shipping. The proposed Bardolino development is approximately 40 km from the UK/Norway median line. The deployment and retrieval of anchors for the semi-submersible drilling rig would cause localised temporary disturbance and interference over an area of seabed estimated to be
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13 th March 2008 Dear Sir or Madam,
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To: Paul Wood Shell U.K Limited, Se
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What risks to marine mammals do pil
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Noise propagation modelling. Noise
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If, for any reason, piling operatio
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APPPENDIX 1 MARINE MAMMAL RECORDING
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ENVIRONMENTAL STATEMENT BARDOLINO DEVELOPMENT

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