Sandwich Town Tidal Defences Environmental Statement Non Technical Summary

Transcription

1 Sandwich Town Tidal Defences Environmental Statement Non Technical Summary Environment Agency

2 Introduction The Environment Agency is proposing to construct a scheme to reduce the risk of tidal flooding within Sandwich, Kent. An Environmental Statement (ES), which describes the potential Environmental impacts of the scheme and how these are to be addressed, has been produced to support the planning application. The ES has been prepared in accordance with the Town and Country Planning (Environmental Impact Assessment) Regulations 1999 for England and Wales and the Environment Agency s own guidelines. This Non-Technical Summary (NTS) provides an overview of the ES. Background The town of Sandwich is located on the East Kent coast, National Grid Reference (NGR) TR The study area for the scheme comprises the Stonar Loop on both banks of the River Stour around Sandwich. The study area starts from the A256 road bridge north-west of Sandwich downstream through Sandwich, continuing past Stonar Lake and the Broad Salts area to the eastern end of the Stonar Cut, and on to the mouth of the river. A total of 8km of river front and 16km of river embankments are within the study area. The study area, together with the key environmental designations are shown in Figure 1. The primary risk to flooding in Sandwich is from a tidal surge moving up the river Stour and flooding properties. Computer modelling has determined that there are currently 409 residential properties and 94 commercial properties at risk of flooding during a 1 in 20 year flood event. Over the next 100 years, the number of properties at risk from flooding will increase to 863 and 165 respectively as a result of predicted sea level rises associated with climate change over the next 100 years. Other key assets currently at risk include Discovery Park (formerly the Pfizer Global Research facility), a number of Grade 1 and 2 listed buildings, Scheduled Monuments, and approximately 3km 2 of agricultural land. Key infrastructure such as the A256 and the railway line will also become exposed to flood risk in the future with sea level rise. Pegwell Bay to Kingsdown Coastal Strategy, produced jointly in 2008 by the Environment Agency and Dover District Council explored three different options for reducing flood risk in Sandwich town. The strategy held a series of public exhibitions in 2008 to consult on these options. The options considered were:- Option 1 : Do Nothing, this option was not considered as there would be progressive deterioration in the standard of protection as a result of climate change impacts on sea level rise. There would be increased frequency of flooding causing lasting damage to historic environment and health impacts as people have to live with the risk of flooding. Option 2: Maintain, this option was not considered as there would be a risk of flooding increasing over time due to climate change with increasing risk to public property and the environment. Option 3 (Improve 1) raising defences along the River Stour to increase the standard of protection. These defences will have to be raised again in 50 years to keep pace with sea level rises. This option was not considered further, when compared to the preferred option there were higher costs associated with this option and significant Landscape and Heritage visual impacts from a high wall >3 metres, in the town.

3 Figure 1 Location map and Environmental Designations

4 Preferred option: Option 3 (Improve 2) Tidal storage and defences Construction of a tidal storage facility in the Broad Salts area. This includes the construction of a spillway, embankments and a drainage facility. A smaller tidal storage facility will also be created within Monks Wall Nature Reserve. The current defences will also need to be raised, but not as much as if defences were the only protection (Improve 1). This option was chosen as it improved the current standard of protection. The raising of defences through Sandwich will be kept to a minimum. It will provide protection of the historic environment and ecologically designated sites. There is potential for approximately 23ha of wetland habitat to be developed. It reduces flood risk to the residential properties of Sandwich. It protects local businesses from flooding, and was the leading economic solution. Option 3, Improve 3 Tidal barrier and defences A tidal barrier would be constructed on the River Stour near Richborough Port. The existing embankments on the eastern bank of the River Stour would be raised and strengthened and extended to the coast north of Sandwich Bay Estate. The defences will also need to be raised, but not as much as for option 3 (improve 1). This option was not considered further as there were higher costs associated with it, and there would be a Habitat Regulations impact to designated interest features from alteration of water levels. Therefore option 3 (Improve 2) was taken forward as the preferred option. Description of the scheme The preferred option, option 3, Improve 2 comprises: Raising and/or improving of the existing defences along the River Stour, including earth embankments, brick faced reinforced concrete flood walls and sheet piled flood walls. Improved quayside area and access in Sandwich along the banks of the river in place of the western part of the existing car park. The new quayside area will allow improved amenity with seating. A Tidal Flood Relief Area (TFRA) downstream of Sandwich in the area known as Broad Salts. The TFRA will include a reinforced spillway; borrow pits, outlet structures and new embankments. The borrow pits will be landscaped and surrounding area will be used to create new habitats, with grazing and wetland grazing. For design purposes the scheme has been divided into 16 reaches, which are shown on the scheme Location Map Figure 1. The 16 reaches are Reach 1- Richborough Road North (includes Reach 1A), Reach 2- Richborough Road South, Reach - 3 Gazen Salts, Reach 4 - Strand Street, Reach 5 - Sandwich Quay, Reach 6 - Sandwich Haven, Reach 7 - Black Sluice, Reach 8 Spillway, Reach 9 Flagstaff, Reach 10 - Princes Golf Course (North and South), Reach 11 - Princes Golf Course Tie-in, Reach 12 - Monks Wall Nature Reserve (includes Reach 12A), Reach 13 - Willowbank Development Site, Reach 14 - Sandwich

5 Industrial Estate, Reach 15 - Stonar Lake and Reach 16 - Discovery Park (formerly Pfizer Global frontage). The Existing Environment The scheme passes through a variety of land uses, including the industrial areas of Discovery Park in the north, the commercial and residential areas of Sandwich town, and areas of agriculture, recreation and nature conservation. The key infrastructure located close to the scheme is the A256 and A257 roads, with Ash Road/Strand Street through Sandwich town. The mainline railway is located adjacent to Reaches 1, 2 and 3 of the scheme. The River Stour itself is important for boating and leisure activities. The study area, in parts, is subject to international and national nature conservation designations. The river corridor of the Stour from the coastline to the town centre forms part of the Thanet Coast Sandwich Bay Special Protection Area (SPA) and Ramsar Site, Sandwich Bay Special Area of Conservation (SAC), as well as the Thanet Coast to Hacklinge Bay Site of Special Scientific Interest (SSSI). The locations of designated features are indicated on Figure 1. Sandwich town centre comprises a Conservation Area and several listed buildings and Scheduled Monuments are located within and in the vicinity of the study area, further details are provided in chapter 11 - Cultural Heritage in the Environmental Statement. Approach to Environmental Statement The scope of issues assessed within this EIA has been determined through a scoping stage, which included consultation with Dover District Council and the MMO, the purpose of the Scoping stage is to provide focus for the Environmental Report. The following environmental receptors or subjects were scoped in for detailed assessment within the Environmental Statement: Planning Policy; Flora and Fauna; Water Resources; Acoustics; Cultural Heritage; Traffic and Transportation; Soils, Geology and Hydrogeology; Landscape; Human beings; Health Impact Assessment; and Cumulative Assessment. Subjects that have been scoped out of the detailed assessment are: Air Quality

6 Environmental Statement - Methodology In order to assess the impacts to the receiving environment, the Environmental Statement has assigned values to environmental receptors according to the relative importance of the feature, i.e., whether it is of international, national, regional, local or less than local importance (for example, in the assessment of flora and fauna a protected species or habitat might be of national or international importance) or by the sensitivity of the receptor (for example, in the assessment of noise, generally humans are more sensitive to noise at night or birds during breeding season). This means that the Environmental Statement can then concentrate on the more significant impacts and assign a value to them, Major, Moderate, Minor or Negligible. It s important to note that significance can be both beneficial as well as adverse. Table 1 below shows how these values have been assigned. Table 1 Impact Significance based on sensitivity or value of receptor and magnitude of impact Magnitude Sensitivity/Value High Medium Low High Major significance Moderate significance Minor significance Medium Moderate significance Minor significance Negligible significance Low Minor significance Negligible significance None Negligible Negligible significance None None In order to conclude the significance to the environmental receptors, as series of baseline collection, surveys and studies were completed prior to the Environmental Statement. Environmental Impact and Mitigation Measures Using the methodology above the Environmental Statement has assigned significance to a range of environmental receptors. Due to the size of the scheme this non technical summery will only concentrate on the Major significant effects. The following issues have been assigned as major environmental significance as a result of the schemes implementation:

7 Major Environmental impacts and Residual impact post mitigation Key Major adverse significance Moderate adverse significance Minor adverse significance Negligible significance Minor beneficial significance Major beneficial significance. Receptor Description of Impact Significance of predicted effect prior to mitigation Flora and Fauna (adverse/ beneficial) Mitigation Measures/ Compensation Significance of residual effect (adverse/ beneficial) Thanet Coast and Sandwich Bay Special Protection Area, designated for assemblage of rare overwintering, breeding and migrating birds. Habitat clearance/ site preparation including tree clearance, construction of Tidal Flood Relief (TFR) spillway, embankment raising and sheet piling/ flood wall, embankment backwall construction Major adverse at international level Generic mitigation measures to minimise footprint of construction activities. Specific bird mitigation measures, in particular managing works to avoid disturbance of high tide roosts. Negligible Thanet Coast and Sandwich Bay Ramsar Site, designated for assemblage of rare birds, invertebrates and habitats Habitat clearance/ site preparation including tree clearance, construction of TFR spillway, embankment raising and sheet piling/ flood wall, embankment backwall construction Major adverse at international level Generic mitigation measures to minimise footprint of construction activities. Site management to prevent pollution of water. Creation of new wetland area, combined with measures to transport material from in-filled ditch to inoculate new ditches. Net beneficial impact significant at Parish/District level (minor)

8 Receptor Flora and Fauna Description of Impact Significance of predicted effect prior to mitigation (adverse/ beneficial) Mitigation Measures/ Compensation Significance of residual effect (adverse/ beneficial) Sandwich Bay to Hacklinge Marshes Site of Special Scientific Interest designated for assemblage of rare birds, invertebrates and habitats Habitat clearance/ site preparation including tree clearance, construction of TFR spillway, embankment raising, sheet piling, flood wall, embankment construction Major adverse effect on grassland, inter-tidal habitats and bird species at national level Generic mitigation measures to minimise footprint of construction activities. Creation of new wetland habitats and translocation receptor sites (for reptiles) will increase the overall area of semi-improved grassland and benefit the assemblage of bird species. Negligible impact on all features Inter-tidal mud, Inundation vegetation, open water & Saltmarsh Sheet piling and working close to water Major adverse at national level Site management to prevent pollution of water. Creation of approximately 5ha of intertidal habitat due to the construction of a set-back embankment arrangement in Reaches Negligible Net beneficial impact significant at Parish/District level (minor) Semi-improved grassland Habitat clearance/ site preparation, Construction of TFR spillway, sheet piling, flood wall, and online embankment raising Major adverse at national level as SSSI feature Generic mitigation measures to minimise footprint of construction activities. Botanical survey to identify value of translocation of turves. Protection of topsoil and re-use of seed bank. Negligible Birds Habitat clearance/ site preparation including tree clearance Major adverse at up to national level Sensitive working practices to minimise disturbance. Creation of new wetland habitats (and translocation sites for reptiles) will enhance habitat biodiversity and provide suitable habitat for the assemblage of bird species. Negligible

9 Receptor Flora and Fauna Description of Impact Significance of predicted effect prior to mitigation (adverse/ beneficial) Mitigation Measures/ Compensation Significance of residual effect (adverse/ beneficial) Invertebrates Habitat clearance/ site preparation Major adverse at national level within Ramsar site Creation of new wetland area, combined with measures to transport material from in-filled ditch to inoculate new ditches Net beneficial impact significant at Parish/District level (minor) Seals Installation of sheetpiling vibration disturbance Major adverse at national level Monitoring of river channel prior to and during any works carried out within the river Stour (Reaches 4 & 14) Negligible Reptiles Habitat clearance/ site preparation Major adverse at up to national level Translocation programme/ creation of new habitat as receptor site in reach 12. Negligible in short term. Net beneficial impact in long term significant at Parish/District level (minor) Water voles Construction of TFR spillway, sheet piling, flood wall, & embankment raising Major adverse at up to national level Mitigation strategy including displacement techniques or relocation by trapping (if required).. Negligible

10 Receptor Noise and Vibration Description of Impact Significance of predicted effect (adverse/beneficial) Mitigation Measures/ Compensation Significance of residual effect (adverse/beneficial) Properties along Strand street. Noise increases due to piling activities Major adverse Ensure that the number of days that receptors are subjected to high levels of noise is kept to a minimum. This will be addressed in the construction programme Community liaison to identify key sensitive times & avoid noisy activities if possible. Monitor noise levels & adjust working methods/times to reduce noise impacts if they are found to be greater than predicted Moderate adverse It is possible that for the nearest receptor properties and the noisiest activities there may be durations of a number of days when the mitigated noise levels exceed 75 db (A), in which case a short term major impact could result.. The noise monitoring and action feedback will address this risk. Traffic and transport Residential roads Strand Street, St George s Road, Manwood Road, Paradise Row, St Barts Road and certain areas of Dover Road Increased traffic levels due to construction related vehicles Major adverse Consultation and liaison with the local authority and Kent Highways. Comply with speed and weight restrictions. Signage to direct construction traffic to working areas Visibility for other road users to maintained. Minor adverse Contractors to be made aware of any passing points. Working areas provide enough space for parked construction vehicles and turning of HGV

11 Receptor Description of Impact Significance of predicted effect (adverse/beneficial) Mitigation Measures/ Compensation Significance of residual effect (adverse/ beneficial) River network Boating access restrictions, reduction in facilities available including mooring areas. Major adverse Construction activities affecting the River Stour will be timed where possible outside of the peak boating season of spring and summer. Liaison with Harbourmaster throughout construction. Moderate/minor adverse Safe systems of work to control river traffic during construction operations. PRoW network surrounding the works areas Diversion or closure of PRoW during construction period Major adverse Any temporary closures and diversions to be discussed with Kent Highways Services. Plans for diversions will be clearly advertised prior to construction. Moderate/minor adverse Diversion of affected routes will be clearly signed and have appropriate safe access. Human Beings Business Users Reduced flood risk to commercial properties once the scheme is completed Loss of agricultural land in Reaches 8 to 11 during construction Major beneficial None Major beneficial Major adverse Financial compensation arrangements Moderate adverse

12 Receptor Description of Impact Significance of predicted effect (adverse/beneficial) Mitigation Measures/ Compensation Significance of residual effect (adverse/ beneficial) Residents Reduced flood risk to residential properties once the scheme is completed Major beneficial None Major Beneficial Disruption and disturbance during construction activities Major/moderate adverse Community liaison officer to be appointed to oversee and feedback concerns. Moderate/minor adverse

13 Landscape and Heritage The Environmental Statement also includes the impacts to designated heritage and landscape features. These were assessed in the Environmental Statement as being of high sensitivity, however, prior to mitigation being in place, these features were considered to be only moderately impacted on by the proposed works, so were not included in the table above. Landscaping will be incorporated into the design, especially as the works will have a moderate effect on the historical and landscape setting of Sandwich Town. Cladding of the new walls in appropriate local brick types, and a new public area in Sandwich Quay to include new seating, will be incorporated into the design. We will work with the conservation officer and local consultees to offset any impacts to the historic listed buildings and the heritage landscape of Sandwich. An example concept of how Sandwich Quay might look post scheme is shown in figure 2 below. Figure 2 Indicative landscape detail for Sandwich Quay Please note that this design is likely to be amended during the planning permission and consultation process. There will be a slight reduction in car parking of 15 spaces to accommodate the flood defences and open space with seating, the majority of the car parking spaces will be left in place. The scheme will be implementing a series of embankment, wall and steel sheet pile raising. Levels will be raised greater in the current low spots, therefore the height of the new defences will range from 0.1 metres to 2.6 metres above current levels. The highest raising will be in Reach 8-11 outside the town. Within the town, reach 4 - Strand Street will be raised to a maximum of 0.45 metres above the current level, which is roughly the height of an average chair and at reach 5 - Sandwich Quay, the wall and embankment will be raised to a maximum of 0.9 metres above current height, which is roughly the height of the average kitchen worktop. It s anticipated that these heights will not adversely affect the town s character or connection to the river setting. There will be an impact to trees from the scheme. In places, there are a large number of trees and shrubs growing on the current flood defences, these will need to be removed prior to the works. Reach 3 Gazen Salts and Reach 12 Monks wall, particularly the area behind Highway Marine, will be most affected by tree removal. Trees cause a hazard to flood defences, if large trees are allowed to grow on defences during storms they could fall, creating significant weakening. The scheme has

14 been designed to avoid most areas of trees, however where they do need to come out, trees will be replanted away from the defences to mitigate for the loss. Environmental Opportunities Sandwich Quay Reach 5 Figure 2 shows indicative details of the new open plan seating area in Sandwich Quay. This will enhance the existing area for people to enjoy the river views. New Downs Farm Reach 8 to 11 Within New Downs Farm an area of approximately 58ha will be used to win material to create the flood defence embankments and spillway, as part of the scheme approximately 23ha will be excavated to enhance the biodiversity. Ground levels will be generally lowered to near groundwater; this will create an area of wetland during the winter only, and some areas of ponds. During the winter months, rare over wintering birds can utilise islands within the fields for roosting and wetland areas for feeding. In the summer the area can be sensitively farmed to provide a hay crop and cattle grazing, along with an area for lapwing. Example of newly created winter wetland area at Rye Harbour Farm, April A similar wetland habitat will be created at New Downs Farm. Monks Wall Reach 12 Part of reach 12 West of Highways marine, the current embankment will be formalised to create a small spillway and tidal flood relief area, this will allow the river eventually, with sea level rise, to reconnect to its natural flood plain. The main flood defence embankments will be setback towards Monks Way Road and the area between the river and Monks Way road will become a wetland nature reserve over time.

15 Conclusions The main environmental impacts of the scheme will be during construction and will be temporary in nature. The key residual environmental effects will be noise and vibration from the construction in the town centre; this will be controlled and monitored. Traffic could be impacted, including footpaths, boat users and roads; this will be temporary in nature and will be timed to avoid peak periods and the key summer season. Mitigation such as diversions or traffic lights might have to be in place temporarily whilst the works are carried out. The new walls in Sandwich town will be keyed in sensitively to the surrounding historic landscape. There will be lasting long term benefits as a result of the scheme. The town of Sandwich will be defended from a 1 in 200 year flood event, the new defences will protect an area of significant job creation at Discovery Park The scheme will create a new public space at Sandwich Quay and as a by product of excavating material at New Downs Farm, a large area of wetland habitat will be created further enhancing the areas unique range of habitats and creating a new biodiversity resource on Sandwich Towns doorstep. Subject to planning approval and receipt of the necessary funding for the work, the tidal defence works in Sandwich is anticipated to commence in winter (January) 2013 and to be completed by spring The assessments presented in this ES are based on this programme.