Southern Strategic Support Main Non-Technical Summary

Transcription

1 Southern Strategic Support Main Non-Technical Summary April 2016

2 Bristol Water SOUTHERN STRATEGIC SUPPORT MAIN NON-TECHNICAL SUMMARY Non-Technical Summary INTRODUCTION Bristol Water is applying for planning permission to install a new water trunk main in Somerset. The project is called the Southern Strategic Support Main (SSSM). An Environmental Impact Assessment (EIA) has been carried out to understand the effects that the new pipeline will have on the environment. The results of the EIA, including details of how to prevent or minimise negative environmental effects, are reported in an Environmental Statement. This Non-Technical Summary summarises the important findings of the EIA. THE LOCATION The proposed pipeline is approximately 31km in length, between Cheddar, Banwell and Barrow Gurney. Approximately 26km of this is located within the administrative boundary of North Somerset Council. The remaining 5km is located within Sedgemoor District Council. An outline of the proposed pipeline route is shown in Figure 1. Figure 1 SSSM Pipeline Route i

3 Bristol Water SOUTHERN STRATEGIC SUPPORT MAIN NON-TECHNICAL SUMMARY THE PROBLEM Banwell and Cheddar WTWs are currently ranked amongst Bristol Water s most high risk assets with limited resilience associated with them. Significant growth (in business and population) is expected in these areas by As such, the Southern Resilience Scheme has been developed to provide future security of supply to over 280,000 customers across the Bristol Water supply area, including Weston-super-Mare, Cheddar, Burnham, Glastonbury and the southern part of Bristol. The scheme will give Bristol Water increased flexibility and allow water to be moved from northern sources into the southern region in the event of loss of supply or water back up to Bristol if the northern supply is lost. THE SOLUTION The Southern Resilience Scheme will be delivered through a series of projects. The first of these is the SSSM project. This will be achieved by constructing a new pipeline linking Cheddar WTW, Barrow WTW and Banwell Riverside where there is an existing water main. Additional works required include the addition of a new pumping station within an existing building at Cheddar WTW and the construction of a small kiosk (approximately 2.55m x 2m x 2m high) at Banwell Riverside to control the flow of the pipeline. Bristol Water has been set a deadline of March 2018 to complete the works by the water regulator OFWAT. ALTERNATIVE SOLUTIONS CONSIDERED Ideally, the proposed pipeline route would avoid all environmental constraints, however the size, nature and location of the project is fundamentally controlled by technical requirements to meet demand and therefore this is not always possible (e.g. the three fixed end points at Barrow WTW, Cheddar WTW and Banwell Riverside had to remain the same). Detailed refinement of the route between these fixed points has been undertaken to help reduce environmental effects so far as possible from the outset. Initially 58 potential pipeline routes were shortlisted for consideration. These routes were subsequently evaluated and refined before the final proposed route was eventually chosen. The options appraisal took into account the following key constraints: Bristol Airport; Hydraulics (including the length and level of the pipeline); Major roads such as the A38 and A370; Rivers; Designated nature conservation sites and their associated species; Archaeology; and Geology. The primary reasons for the selection of the preferred option include: The route meets the requirements of the scheme at the lowest cost to Bristol Water customers. ii

4 Bristol Water SOUTHERN STRATEGIC SUPPORT MAIN NON-TECHNICAL SUMMARY The route avoids the need to lay pipeline along the A38 through Sidcot, which would lead to significant traffic impacts and disruption to Sidcot School. The route is at least 2km shorter than all other options which reduces the amount of resources required. The route offers significant long-term savings in operational cost and energy consumption. The route avoids all European-designated statutory nature conservation sites and Scheduled Monuments. The map below gives an indication of some of the initial options short-listed for consideration in comparison with the preferred route. There are still a small number of locations where short sections of alternative pipeline routes are being refined including Backwell Down Manor, Farleigh Combe Manor, Backwell, Pitt Lane, southwest of Meetinghouse Lane, and Mead Farm. In these locations landowners have been kept informed of the works and the route will be confirmed with the planning authority prior to construction. All remaining options are assessed within the Environmental Statement. Figure 2: Overview of alternative pipeline routes considered In addition to refinement of the pipeline route, consideration was also given to alternative construction methodologies to be used at various locations (see Proposed Construction Methods for more detail). iii

5 CONSULTATION Key statutory and non-statutory consultees have been consulted to various degrees by Bristol Water in advance of the submission of the planning application. Examples of the groups consulted include: Sedgemoor District Council North Somerset Council Somerset County Council South West Heritage Trust Natural England Historic England Environment Agency The Wildlife Trusts The RSPB Directly affected residents Banwell Archaeology The Strawberry Line Society Local Highways Authorities Parish Councils Yatton and Congresbury Wildlife Action Group Mendip Hills Area of Outstanding Natural Beauty (AONB) Trust Generally consultation has not resulted in any fundamental changes to the scheme proposals but did highlight areas that needed to be considered in more detail, including additional requirements for the avoidance or reduction of potential environmental effects. The works will be subject to a planning application (see The Planning Process below) and therefore statutory and non-statutory consultees will have the opportunity to provide further comment during the determination period. Further consultation is proposed during construction, including: Continued engagement with affected landowners and the local community through letters, workshops, direct calls and press releases; Continued engagement with Parish Councils across the pipeline route; With Natural England with regard to protected species mitigation; and With statutory authorities, including Historic England and the County Archaeologists, with regard to archaeological mitigation. PROPOSED CONSTRUCTION METHODS Pipeline construction will be carried out in accordance with best practice techniques that have been developed through experience to mitigate environmental damage and to develop good relationships with local landowners during construction. The pipeline will be constructed using a spread method whereby crews responsible for different construction activities move forward, following each other at intervals of several days, along the route. All construction activities will take place within an agreed working strip. For the majority (176) of field crossings (hedges / walls / fences) the working widths will be restricted to 7m to ensure any bats possibly commuting along the linear crossings are not affected although there are 19 instances where a 10m width may be required.

6 Generally the proposed pipeline route has been designed to avoid trees wherever possible. In total however there will be a loss of approximately 160 trees. The majority of these form parts of hedgerows, however 15 are standalone trees although only one is considered to be mature. Additional trees may also require limb removal, for example, to facilitate construction access. Contractors will adhere to strict method statements to ensure works close to other trees do not cause further unnecessary damage (e.g. by avoidance of work over tree roots and installing exclusion fencing around trees). Where relevant, loss of vegetation has been assessed in relation to Flora and Fauna and Landscape Character and Visual Amenity (see below). A range of construction methodologies are required across the pipeline length. These are summarised below. Open Cut Construction Methodology (over land) The vast majority of the pipeline will be constructed using this method. Where present, topsoil will be stripped from the land within the working width and stored to one side in stockpiles up to 2m in height. The stored topsoil will be sealed and graded to prevent excessive ingress of water, prevent ponding and allow surface water to run off. A trench, generally no more than 1.7m deep, will then be excavated and the subsoil stored on the opposite side of the trench to the topsoil in piles up to 3m in height, with suitable supports if necessary. The lengths of pipe will be positioned along the route. The pipeline will be lowered into the trench, onto an appropriate bedding material (for example, depending on whether it is laid on rock or clay material), using excavators in continuous operation. After each section of pipeline is completed the pipeline will be pressure tested with water before the subsoil and topsoil is reinstated. Trees and hedges will be re-instated in the first growing season following completion. Open Cut Construction Methodology (over water) The Lox Yeo, Land Yeo and all other small water courses/ drainage ditches will be crossed using the above methodology, however the watercourse will be either stanked or flumed before works start. Stanking involves the placement of steel trench sheets either side of the working area to dam the ditch so that the pipeline can be laid in the dry. Water which collects in the area dammed off will be over-pumped as necessary into the water either side of the steel sheets. Measures will be implemented to avoid causing flooding upstream in the event of high water levels. For shallower, faster flowing watercourses temporary pipes (flumes) will be used to divert the flow so that the pipeline can be constructed underneath while normal flows are maintained. Once the pipeline has been installed temporary subsoil will be placed over the flumes to provide a platform to allow construction traffic to pass over the watercourse. Following completion of all works close to watercourses, the banks will be fully reinstated to their former condition. i

7 Plates 1 and 2: Examples of open-cut methodologies over watercourses: Stanking (left) and fluming (right) No-Dig Construction Methodology In some instances to avoid environmental constraints a no-dig methodology will be used to ensure the lowest possible impact. This will be achieved by directional drilling or auger boring. It is proposed to use a no-dig construction methodology at the following locations: Through Church Wood, Barrow for a length of approximately 150m. At the Rhodyate Hill road crossing for a length of approximately 75m. At the Congresbury Yeo river crossing for a length of approximately 80m. Directional drilling involves the establishment of launch / receptor pits (approx. 2m x 2m x 1.5m deep) at either end of the section to be drilled. The pipeline will then be strung out and jointed within the defined working area. A hole will then be drilled beneath the obstacle from launch pit to receptor pit in a long arc beneath the ground. By repeated drilling using progressively larger drill bits, the hole will then be opened large enough for the pipeline to be pulled through the hole. Auger boring also requires launch /receptor pits. This method involves boring a horizontal tunnel beneath an obstacle and inserting a liner sleeve pipe in to the tunnel to prevent it collapsing. The proposed pipeline is then installed inside the liner pipe. The liner pipe will typically be steel and the launch pit will be long enough to accommodate the full length of liner pipe so that it can be welded together in the trench. Plate 3: Typical example of auger boring ii

8 THE PLANNING PROCESS Water companies, such as Bristol Water are often able to use Permitted Development rights to undertake works such as the installation of pipelines without the requirement for planning permission. However, in line with EIA procedure a screening opinion was sought from Sedgemoor District Council and North Somerset Council. In this instance, both authorities determined that the proposed works had the potential to give rise to significant environmental effects and as such a planning application is required for the works, supported by an Environmental Statement. PROGRAMME Upon submission of the planning application, the Local Planning Authorities (i.e. North Somerset and Sedgemoor District Councils) have 16 weeks to provide a decision. If a positive decision is received works will commence as soon as possible in certain sections, such as the establishment of construction site compounds. Subject to receiving planning and any other consents work are due to commence in August 2016 and continue for 19 months (excluding re-instatement). It is possible that some elements of the SSSM project may be subject to planning conditions; if this is the case these will be fully discharged before those elements of works commence. The pipeline must be in operation by 31 st OFWAT. March 2018 to meet the regulatory deadline set by THE ENVIRONMENTAL IMPACT ASSESSMENT In order to inform the content of the Environmental Statement a request for a scoping opinion was issued to both planning authorities. The request for scoping opinion stated Bristol Water s intention to only assess the following aspects of the environment in detail due to the projects potential to give rise to significant effects: Flora and Fauna including statutory designated conservation sites, locally designated wildlife sites, Local Nature Reserves, hedgerows, trees, grassland habitats, running water habitats and protected species including bats, dormice, badgers, birds and great crested newt. Traffic and Transport, including construction effects to the local road, cycle and footpath network. Historic Environment, including Listed Buildings and potentially archaeologically sensitive sites. Landscape Character and Visual Amenity including effects to the Mendip Hills AONB, Conservation Areas and views from dwellings, footpaths and cycle routes. Cumulative Effects that may arise from the SSSM project in-combination with the effects of other known plans and projects. In addition to the topics suggested above, Sedgemoor District Council also requested that the assessment consider the following issues: Flood Risk: This has been considered as part of the Flood Risk Assessment submitted in support of the planning application, the results of which are summarised in the Environmental Statement. iii

9 Environmental Management: A scheme for the prevention of pollution during the construction phase has been included as part of a Construction Environmental Management Plan, included within the Environmental Statement. Public Rights of Way and National Cycleways: An assessment of potential effects has been included within the assessment of Traffic and Transport. Landscape Character; Views from the A38 looking north near the Old River Axe and views from the edge of Sandford Quarry have been included within the Landscape and Visual chapters of the Environmental Statement. Other aspects of the environment; e.g. noise and air quality, were scoped out of detailed assessment but mitigation has been included in a Construction Environmental Management Plan where required to minimise environmental effects. The EIA considered the existing condition of the environment and the way this may change as a result of construction and operation of the project. When negative effects were identified, ways of preventing or reducing the scale of the effects were considered. In some cases it was possible to alter the design of the project to avoid or minimise effects, for example by routing the pipeline around statutory designated sites or avoiding particularly sensitive trees or hedgerows. In other cases actions will need to be carried out during construction, for example measures to protect known bat roosts. All of the actions needed to minimise negative effects on the environment have been set out in a Construction Environmental Management Plan. This will be followed and updated as the project progresses. The key findings of the EIA are summarised in the following sections. HISTORIC ENVIRONMENT The Scheme route has been located to avoid designated heritage assets and known highly sensitive archaeological areas. A Desk-Based Assessment, geophysical survey of the route and archaeological watching brief of ground investigation works informed the assessment. Areas along the pipeline route have been found to have varying historic and archaeological value. Potential interest features include: Barrow Gurney and Long Ashton o Evidence of 19 th century field boundaries o Limited remains of unknown date and value Flax Bourton and Backwell o Evidence of the medieval occupation of Backwell o Evidence of agricultural and mining activity Brockley, Cleeve and Yatton o Medieval and post-medieval remains of agriculture and farmsteads Congresbury and Churchill o Archaeological remains near Cadbury Hillfort Scheduled Monument o Evidence of Romano-British occupation and industry near Congresbury and Brinsea o Post-Medieval and 19 th Century agricultural remains Banwell, Winscombe and Sandford o Prehistoric remains o Romano-British features o 19 th Century farming activities iv

10 Compton Bishop, Axbridge and Cheddar o Medieval or later agricultural remains Any construction works which require removal of the topsoil and subsoil may impact on archaeological deposits or features. This can include works associated with temporary compounds and haul roads as well as trenching/drilling undertaken along the pipeline itself. These works therefore have the potential to result in damage to or loss of any archaeological features present within their footprint, resulting in a total or partial loss of the heritage significance of these assets. Plate 4: An archaeological watching brief was undertaken during ground investigation works Mitigation strategies will be agreed with statutory authorities prior to works commencing. This is likely to include a mixture of the following: Targeted strip, map and sample of areas of high archaeological potential/known archaeological remains of moderate-high value; Targeted watching brief of archaeological remains of moderate-low or unknown value; and Watching brief on areas not covered by the geophysical survey With the implementation of mitigation there will be no significant effects on the historic environment. LANDSCAPE CHARACTER AND VISUAL AMENITY Within the Environmental Statement landscape character and visual amenity are assessed separately. Landscape character refers to a distinct, recognisable and consistent pattern of elements in the landscape that makes one landscape different from another. An assessment of the proposed works on landscape character concluded that with the implementation of mitigation, primarily in the form v

11 of reinstatement planting, no effects will be significant after five years. For example, at the southern end of Backwell Farleigh Conservation Area there may be adverse effects at a very local level due to replacement planting not fully re-establishing within five years to the height of the vegetation removed, however this is not assessed as significant. The only effect on landscape character after five years in the Mendip Hills AONB is as a result of two sections of mature tree removal however this is not considered significant. Plate 5: The SSSM will run within sections of the Strawberry Line Visual amenity assessment is concerned with the extent to which views, as experienced by specific groups of people (including from residential dwellings, Public Rights of Way (PRoWs) and visitors to heritage assets), are altered as a result of a development. The principal change that will be noticed by residents of private dwellings and users of PRoWs will be loss of hedgerows and in a small number of locations, loss of mature trees. As these effects are largely caused by hedgerow removal, the effect on these receptors will be reduced over time as replacement hedgerow planting establishes. It is considered that after five years, there will be no residual significant effects on visual amenity. FLORA AND FAUNA The assessment of effects on flora and fauna has been informed by detailed desk-based assessment and a comprehensive scheme of habitat and protected species surveys. The SSSM route has been designed not to pass directly through any European statutory nature conservation sites however it does pass close to some site boundaries including the North Somerset and Mendip Bats Special Area of Conservation (SAC) and Mendip Limestones SAC. Detailed assessment of potential impacts on the SACs and on species associated with them (lesser and greater horseshoe bats) has been undertaken in consultation with Natural England to inform the vi

12 planning application. This concluded the SSSM project will not result in any significant adverse effects (see bats below). A temporary diversion of the Strawberry Line adjacent to Cheddar Reservoir Site of Special Scientific Interest (SSSI) may lead to increased levels of disturbance to overwintering birds using the site. Public notices will be erected to inform the public of the overwintering bird interest and encourage them to reduce noise levels. Works will be required within Cheddar Valley Railway Walk Local Nature Reserve (LNR) as well as five North Somerset Wildlife Sites (NSWS). Where this is the case there will be a temporary loss of some vegetation and habitats but these will be fully reinstated upon completion of the works, informed by detailed pre-construction surveys. Church Wood will remain unaffected by the works through use of a no-dig construction methodology. Bat species, including horseshoe bats, may be present within the SSSM working areas. It is considered that any removal of linear features (walls / fences / hedges / waterbodies) as part of the project could therefore lead to the loss of flight lines for bats. In order to reduce such effects, wherever possible crossing widths have been reduced to 7m. In a small number of instances where this is not possible, the crossing width will be limited to a maximum of 10m. A programme of bat surveys is currently ongoing to determine which hedgerow crossings are used by horseshoe bats. Bat screens will be used in gaps across hedgerows found to be used by horseshoe bats during construction and kept in place until planting has established. A small number of roosting bats have been found in the Shute Shelve Tunnel. The tunnel will be temporarily blocked prior to hibernation season to prevent bats entering and looking for hibernation sites. The works will then commence in winter. Plate 6: Bats are known to roost in the Shute Shelve Tunnel. Cave spiders are also likely to be present Eight badger setts have been identified within 30m of the working corridor and could therefore be disturbed. The pipeline route also passes through suitable foraging habitat. No setts will be vii

13 destroyed by the work, although open trenches have the potential to trap badgers if left open overnight. All works within 30m of badger setts will be fenced off to prevent accidental damage, suitable egress will be left for any trenches left open overnight and open pipes will be capped at both ends each day to prevent badgers from entering. Licenses will be obtained from Natural England for any works likely to disturb a badger sett. There will be no significant impacts on overall breeding bird populations. There is potential to destroy nests when working during the breeding season however all vegetation clearance is designed to avoid this period. Kingfishers may nest on the banks of the Congresbury Yeo; if works fall within the nesting season at this location pre-construction checks will be undertaken by an ecologist. If nesting kingfisher are found an exclusion zone will be set up until the young have fledged. All hedgerows crossed by the pipeline have potential to support dormice. Surveys for dormice will be undertaken prior to works commencing. If nests are found a suitably qualified ecologist will carefully move the nest away from the section of hedge to be removed and replace it in a suitable location. The hedgerow will then be removed under an ecological watching brief prior to the hibernation period. A license will be sought from Natural England for any works to a hedgerow confirmed to support dormice. No ponds will be directly affected by the works however there is potential for individual great crested newts (GCN) to be present within 500m of any pond where they are present. Creating gaps in hedgerows can fragment routes which GCN use to travel between ponds. In addition, GCN may move in to stockpiles. Proposed mitigation includes fencing off working areas, the capture and translocation of any confirmed GCN within 250m of the route and watching briefs; all under a license from Natural England. Plate 7: GCN surveys are being undertaken at all potentially suitable ponds along the pipeline route viii

14 Other notable species present within the proposed working area include cave spiders within the Shute Shelve Tunnel and a rare horsefly within the verges of the Strawberry Line. Mitigation measures will be informed by further survey where required. Toolbox talks will be given to all site staff before starting works to inform them of the risks and action to take in the event that protected species are found. Following the implementation of mitigation the majority of effects to Flora and Fauna are not assessed as being significant. The exceptions to this are the loss of vegetation within the Cheddar Valley Walk LNR, disruption to commuting bats (non horseshoe bat species) from temporary severance of flight lines and fragmentation of GCN habitat; these will have significant effects in the medium-term until vegetation establishes. TRAFFIC AND TRANSPORT The proposed SSSM route will primarily pass through open countryside but will either cross or pass through a number of roads, PRoWs and sections of the Strawberry Line, which also forms part of the National Cycle Network. The majority of road crossings require temporary closure for a short period to facilitate construction. Diversions routes are proposed wherever possible, where not possible, every effort will be made to accommodate pedestrians and cyclists. All diversion routes will be clearly signed. For busier roads, two or three-way traffic signal control will be used, as appropriate, to control and maintain traffic flow without the need for closure. Sites where this is proposed include: Church Town A370 Main Road A368 Towerhead Road A371 Banwell Road A371 Woodborough Road A38 Bridgwater Road Cross Lane A371 Axbridge Bypass Where possible, works will be reduced during daily and seasonal peak time, such as during the school run or the A371 Axbridge Bypass during the school summer holidays. Crossings of PRoWs will generally be short-term and will require localised diversions, but will often be within the same fields. A number of temporary construction compounds are proposed in association with the works, including major compounds, minor compounds and temporary lay-down areas. The main compounds will provide the majority of car parking for construction staff and will accommodate temporary office and welfare facilities. The main compounds are proposed close to higher standards of road to provide good access for staff and delivery vehicles and minimise the strain on lesser roads. In general, where the pipeline runs through fields, construction plant will travel along the length of the pipeline easement. ix

15 A Construction Traffic Management Plan will be used to manage and mitigate potential impacts. There will be no significant effects to traffic and transport following the implementation of mitigation. CUMULATIVE EFFECTS The EIA considered whether changes to the environment caused by the SSSM could interact with other projects or plans to generate larger, more significant effects than would be caused by each project individually. Numerous developments and spatial plans have been identified through an online data search and consultation with the relevant Local Planning Authorities. The main potential for cumulative effects has been assessed as being the result of an overlap of construction programmes between the SSSM and the Hinkley Point C Connection project. A number of the effects identified as occurring as a result of the SSSM project may be exacerbated when considered in-combination with the Hinkley C Connection project. For example, habitat fragmentation and disturbance across the wider area may result in a more significant effect. There is also likely to be increased impacts upon the local road network if construction programmes overlap. Mitigation will continue to be implemented as described in previous sections, however consultation will be undertaken with all third party developers as necessary to reduce effects further. CONCLUSIONS The SSSM project is programmed to be delivered by Bristol Water prior to a regulatory deadline of March 2018 set by OFWAT. The project will have the major positive effect of providing security of water supply to approximately 280,000 customers. In summary, given the nature of the SSSM as an underground pipeline, there will be no effects to the environment once operational. Effects will therefore only be experienced as a direct result of construction activities until reinstatement has been completed and established. The EIA identified a number of potential negative effects on the environment and, where possible, measures to avoid or minimise these effects have been included into the project design. Measures to minimise the scale of effects that cannot be avoided have been developed and recorded in a Construction Environmental Management Plan, which is included within the Environmental Statement. FURTHER INFORMATION If you would like further information on the SSSM project, please contact: Caroline Glanville Bristol Water Stakeholder Liaison Officer Telephone: Caroline.Glanville@bristolwater.co.uk x