Wytch Farm Pipeline Refurbishment Project. Environmental Statement. Non-Technical Summary. November 2007

Transcription

1 Wytch Farm Pipeline Refurbishment Project Environmental Statement Non-Technical Summary November 2007

2 Location map kilometres Development area

3 Introduction BP Exploration Operating Company Ltd (BP) proposes to refurbish part of the underground pipeline system at the Wytch Farm Oilfield in Dorset to ensure that it meets future operational and integrity requirements for the remaining life of the Oilfield. Planning consent for the Wytch Farm Pipeline Refurbishment Project will be sought from Dorset County Council (DCC). The planning application will be accompanied by an Environmental Statement (ES) prepared and submitted in accordance with the Town and Country Planning (Environmental Impact Assessment) (England and Wales) Regulations 1999, as amended. The planning application will cover the route of the pipelines and the temporary works areas, including construction and storage compounds. An Environmental Impact Assessment (EIA) of the project has been carried out. EIA is a means of drawing together, in a systematic way, an assessment of a project s likely significant environmental effects. The process helps to ensure that the importance of the predicted effects, and the scope for reducing them, are properly understood by the public, other interested parties and the planning authority before the authority makes its decision. The findings of the EIA process are presented in the ES and are summarised here. The objectives of the EIA have been to: establish and review the existing environmental conditions in the vicinity of the pipelines; identify any potential environmental impacts that might arise during the construction and operation of the pipelines; assist in identifying appropriate measures to mitigate any adverse impacts; assess the significance of any environmental impacts that may remain after the implementation of the mitigation measures; and provide information to allow the compilation of the ES to accompany the Planning Application to DCC. The EIA involved a range of technical studies, the results of which are summarised below. The studies were supported by consultation with a range of organisations, including DCC, Purbeck District Council, the Environment Agency, Natural England and English Heritage. The full ES is available for the public to view at DCC s office during normal office hours. Copies of the ES and planning application will also be available to download from the Council s online planning website ( Project Overview The Wytch Farm Oilfield development comprises ninety-eight oil production and water injection wells sited at eleven wellsites. The wellsites are connected to a central Gathering Station by a network of underground pipelines. The main facilities are located around the southern shores of Poole Harbour. Regular internal inspection of the pipelines showed that parts of the existing pipeline system have experienced internal corrosion and a number of repairs have been carried out to reinforce the pipelines at these points. In some instances, the repairs have required excavations to take place within areas designated for their nature conservation value. BP now wishes to replace two pipelines between the Gathering Station and Wellsite 2B, a distance of approximately 250 m and three pipelines between the Gathering Station and Wellsite D, a distance of approximately 2 km. Options Considered Three initial options were considered to achieve BP s overall objective: To continue with the existing practice of inspecting and repairing corroded sections of pipeline. This was rejected as it could require further excavations to take place within areas designated for their nature conservation value; To internally line the pipelines affected by corrosion. This was rejected because the linings prevent examination of the pipeline integrity and therefore make the option unsuitable in the long-term; and To replace the corrosion-affected pipelines. This is the selected option. 1

4 A Route Selection Study was then carried out to determine the best route for the replacement pipelines. The study took account of environmental, technical and financial issues. The selected option, described below, was chosen because it minimises the impact on areas of environmental sensitivity while being technically feasible and commercially viable. Project Description The route of the pipelines runs parallel to that used by the existing pipelines and other Oilfield services. The pipelines will carry crude oil and other fluids, including water. The new pipelines from the Gathering Station to Wellsite D will cross Wytch Moor and Shotover Moor using the existing causeways to avoid excavation works in the sensitive areas. The pipelines will be manufactured from carbon steel and will be approximately 15 to 25 cm (6 to 10 inches) in diameter. The pipelines will typically be buried to a depth of 1.1 m, although the depth may need to be reduced across the Wytch and Shotover Moor causeways. The pipelines will be connected to existing above ground piping at the Gathering Station and the wellsites. No additional equipment will be installed on any of the wellsites as part of this work. Construction Construction is currently planned to take place between April and November Normal working hours for general construction activities will be from 0700 to 1900 from Monday to Friday, and between 0700 and 1300 on Saturdays. No works will take place on Sundays or Bank Holidays. Pipeline testing and commissioning, including inspection of the pipeline welding, may be carried out on night shifts or require a continuous 24-hour per day operation. The working area required during pipe laying will be 30 m wide, reduced where necessary, such as when crossing hedgerows and on the Wytch and Shotover Moor causeways. A 30 m working width is required in order to provide sufficient space to excavate the trench for the pipelines; to lay out, weld and inspect the pipelines; to temporarily store excavated soil; and to allow construction vehicles to move along the pipeline route. The working width will be enclosed by a temporary fence. A construction compound will be set up near to Wellsite X. Pipes and other materials will be stored here before being transported to the working width as required. The compound will also house temporary facilities including site offices, stores, workshops, messing facilities, toilets and car parking. Additional mobile facilities such as toilets, security huts and site offices will be located at strategic points along the working width where appropriate. The crossings of the Wytch and Shotover Moor causeways are the most sensitive elements of the construction phase because the causeways pass through areas designated for their nature conservation interest. These works will be defined in detail before construction commences to ensure that these interests are not affected. 2

5 The pipelines will be cleaned and tested prior to commissioning. The working width will be restored to its previous condition. Soil will be replaced and areas reseeded or planted as appropriate. Land drainage and fences will be reinstated and hedges replanted. Operation and Maintenance BP will operate the pipelines as part of the existing Oilfield. The pipelines will be subject to BP s established pipeline protection and inspection procedures. The Oilfield has an Emergency Response Plan to deal with emergency and abnormal conditions. This will be revised in consultation with the appropriate authorities and emergency services to incorporate the new pipelines. Decommissioning This project will result in some of the existing pipelines becoming redundant. These pipelines will be flushed clean, left full of water and sealed. The exception to this is where they need to be removed to create space to lay the new pipelines, e.g. across the Wytch Moor and Shotover Moor causeways. All of the pipelines will be decommissioned at the end of their useful life in a manner that will comply with the requirements and best practice at the time. The current proposal is for the pipelines to be cleaned, filled with water and sealed. Allowing the majority of the buried pipelines to remain in place will avoid the environmental disturbance that would result from their complete removal. The pipelines within the causeways will, however, be removed. 3

6 Ecology The most valued features within, or adjacent to, the development area are the designated sites, namely Poole Harbour Special Protection Area (SPA) and Ramsar site, Dorset Heathlands SPA and Ramsar site, Dorset Heaths (Purbeck and Wareham) Studland Dunes Special Area of Conservation (SAC), Poole Harbour Site of Special Scientific Interest (SSSI) and Rempstone Heaths SSSI. Overall, the proposed pipelines are predicted to have no significant adverse effect on these sites or their associated features of interest. The saltmarsh, wetland and heathland habitats surrounding the development area support internationally important populations of waders, wildfowl and heathland birds. The route of the proposed pipelines avoids the most important areas for these populations. In addition, the major construction works are programmed for the summer, prior to the arrival of the majority of waders and wildfowl. The predicted impacts on these species are considered to be negligible. Two small areas of heathland will be directly affected but these areas are not in the designated areas. The habitat affected will be restored following construction. The route itself supports a small population of reptiles, including slow-worms and common lizards. Any reptiles found within the working width will be relocated to suitable sites. Overall, the impact on reptiles is predicted to be minor. No significant cumulative impacts have been identified on protected or notable species, habitats or designated sites. Landscape and Views The development area is located within the Dorset Area of Outstanding Natural Beauty and Purbeck Heritage Coast. These areas are noted for their landscape and amenity value and are protected through planning policy. The effects of the project on landscape character and visual amenity during the construction phase will not be significant. The pipeline route avoids the most significant landscape features and measures will be implemented to limit impacts upon valued landscape features, such as trees and hedgerows. Only short sections of the route, and the temporary loss of parts of the wellsite tree screens and earth mounds, will be visible to a small number of people, including cyclists and users of public rights of way and private roads. Four hedgerows crossed by the works will be replanted on completion. The effects of the scheme will be minor and temporary, although hedgerows and tree screens will take a few years to regrow. Archaeology and Cultural Heritage Comprehensive archaeological surveys were undertaken when the Oilfield was first developed. The area contains a series of archaeological settlements, funerary sites and evidence of farming activity. These date principally from the Mesolithic (c. 6000BC) to the late Roman period (c. AD400), but with more localised areas of Medieval (c. AD1066 AD1500) and post-medieval activity (AD1500 AD1800). No significant archaeological impacts are anticipated as a result of the project because areas of interest have been avoided. Any archaeological features encountered during the construction work will be recorded. Agriculture, Land Use, Soils and Ground Conditions Land within the vicinity of the development area is agricultural, forestry, heathland, saltmarsh or used by BP as part of the Oilfield. The impacts of the project on agriculture, land use, soils and ground conditions will be negligible. Construction will be managed to minimise disruption. The project will resolve the present minor disturbance arising from repeated pipeline inspection and investigations. Water There are a number of surface water features within the vicinity of the development area. These include ponds, ditches, drains and inlets from Poole Harbour. Some of the features are man-made and associated with BP s wellsites. The nearest river is the River Corfe, located approximately 500 m east of the Gathering Station. Most of the development area falls outside areas at risk from flooding. With the 4

7 appropriate construction management measures in place, no significant impacts on ground or surface water quality, water resources or flood risk are anticipated. Pollution control measures will be in accordance with the requirements of the Environment Agency. These include storage of potentially polluting substances within bunded areas, keeping plant and vehicles out of watercourses and providing spill kits at all appropriate work locations. Traffic and Transport Construction traffic from outside of the area will use the A35 to the Bakers Arms roundabout and then the A351. The A351 runs through Sandford, around the Wareham bypass and then south towards Corfe Castle. The volumes of traffic associated with the construction of the project will be relatively low, peaking at eight movements per hour, two or three of which will be HGVs. The increase in traffic along the A351 through Sandford and along the Wareham bypass will not be significant. A Traffic Management Plan will be prepared in consultation with local highways authorities to minimise the impact of construction traffic on the local highway network. During construction activities on the Wytch and Shotover causeways there may be disruption to the few people who need to travel to the Ower peninsula and Cleavel Point. The Wytch Moor causeway will remain open to traffic, with some minor restrictions during working hours. The Shotover Moor causeway will, however, need to be closed for a period of up to 3 months. During this time, alternative access will be via the original estate track, now a bridleway, which runs across Rempstone Heath. In advance of the construction work, the Rempstone Estate will carry out maintenance work to the bridleway and bridge which will allow the passage of light vehicles and emergency services. Noise and Vibration Noise from the construction works will sometimes be audible at the residential properties at Wytch Farm and Ower Farm. However, periods of highest noise levels will only arise during the limited periods when plant is operating nearby. Activities associated with the causeways and the wellsites will be relatively fixed. They will, therefore, be present for a longer period of time (approximately eight weeks in each case). Given the separation distances between these works and the residential properties, noise levels will remain relatively low. Noise levels will be within the limits set by DCC. Measures to reduce noise impacts will be agreed with DCC and the Environmental Health Department of Purbeck District Council. Levels of vibration will be well below the limits set to protect sensitive buildings and will not give rise to building damage, cosmetic damage or disturbance to occupiers. Emissions and Waste Established BP waste management procedures will be applied to the project and incorporated into an Environmental Management Plan. The procedures will cover the disposal of all types of waste and emissions generated during the construction and operational activities. Wastes generated could include redundant sections of pipeline and general construction waste (including packaging and surplus excavated material). No significant residual impacts are predicted to arise from the generation of waste. There is the possibility that, as a result of conveying untreated crude oil, the redundant pipelines may be contaminated with Naturally Occurring Radioactive Material (NORM). The redundant pipeline sections that are to be removed from the causeway crossings or other locations will be checked prior to removal. If found to be NORM contaminated they will be subject to treatment and disposal as per existing BP Wytch Farm procedures, namely removal to a prepared area for specialist cleaning and transportation off-site to a licensed disposal site. The effects of construction plant and equipment emissions are considered to be negligible. Dust will be controlled using standard techniques such as dampening down working areas in dry conditions and providing wheel washing and road cleaning facilities. No emissions will be released from the pipeline during operation. 5

8 Socio-Economics The project will play an important part in sustaining the future operation of the Oilfield, a major employer and element in the local economy. There is likely to be a positive impact to the local economy as a result of the construction activities, although it is unlikely to be significant. During construction it is estimated that the workforce numbers will peak at around 40. Of these, the majority are likely to be experienced pipeline personnel, whom the Contractor will bring from previous projects. However, local labour may be employed through contracts that would be let on a sub-contract basis. Indirect employment opportunities could also arise through local firms providing services, goods and materials for the construction phase. Environmental Management An Environmental Management Plan (EMP) will be prepared by BP to cover the detailed design, construction, restoration, operation and eventual decommissioning of the project. The purpose of the EMP is to provide a means of delivering the measures proposed to avoid or reduce potentially adverse impacts. The EMP will ensure that standards of good practice are adopted and will allow any unforeseen or unidentified impacts to be dealt with appropriately. The EMP will include details on environmental awareness and training, communication and consultation, further studies required, monitoring and auditing activities and emergency/incident planning. No adverse impacts are predicted on other local economic activities such as agriculture, forestry, tourism and recreation. For further details of the project or to request copies of the Environmental Statement ( for a paper copy or 5.00 on CD) or further copies of this NTS (free) please contact: Dr Suzie Baverstock BP Exploration Operating Company Ltd Gathering Station Thrashers Lane Corfe Castle Wareham Dorset T: BH20 5JR E: suzie.baverstock@uk.bp.com