Non-Technical Summary

Transcription

1 Non-Technical Summary Introduction and Background The Environment Agency owns Rye Harbour Farm in East Sussex and has developed a scheme to enhance the nature conservation value of the Farm, which lies adjacent to Rye Harbour Nature Reserve (Figure 1.1). The proposed scheme comprises creation of intertidal saltmarsh, saline lagoon, wet grassland, lowland meadow and shingle ridge restoration totalling approximately 31 ha. The works require planning permission and fall under the Town and Country Planning (Environmental Impact Assessment) (England and Wales) Regulations SI99/293. A statutory Environmental Statement (ES) has been prepared to accompany the planning application for the proposed scheme to be submitted to Rother District Council. This covers the implications of the project for all aspects of the natural and human environment. The ES was prepared following the collection of baseline data for the study area through consultation with statutory and non-statutory bodies, specialist surveys, site visits and desktop studies. It presents the results of an Environmental Impact Assessment (EIA) of the preferred option for the site. The EIA ensures that the preferred scheme is environmentally acceptable and sustainable. Description of Scheme The scheme to create habitat would involve the following works: (a) (b) (c) (d) Creation of approximately 10.8 ha of intertidal habitat in Field 6 (Figure 2.1) by means of three culverted openings to the River Rother to allow controlled flow of tidal water in and out of the site. The culverts will have an invert level of 2.25mOD which is above the level of neap tides in the Rother estuary, so the site will only flood on spring tides. All three culverts will be provided with penstocks to enable flows of water to be controlled, for example during large surge events. One of the culverts will be fitted with a flap valve to act as an outflow but not an inflow. Construction of a new outfall through the sheet piling that presently bounds the western side of the River Rother to enable water discharged from the intertidal area to drain to the estuary. Excavation of a creek network within Field 6 to encourage the formation of saltmarsh, generating some 6,000m 3 of spoil. Field 5 will be connected to the drainage network in Field 6 by means of a single culvert with an invert level of 2.75mOD. This will allow inflow but not outflow, creating a further 2.6 ha of intertidal habitat. This may be increased in future years by opening up all of Field 5 to tidal inflow, creating a total of 4.9 ha of intertidal habitat. A penstock will be fitted to allow the rate i

2 (e) (f) (g) (h) (i) of saline water inflow to be controlled. The resulting habitat will drain mainly by seepage and evaporation and form a saline lagoon and pan that will tend to dry out during periods of neap tides, low rainfall and high evaporation. Retention in situ of an area of landfilled waste within Field 6, including protection from erosion by saltmarsh creeks using a buried rock revetment, covering with 7,000m 3 of clay material (depth 600mm) to prevent disturbance by burrowing animals and landscaping with a further 2,000m 3 of material. Infilling of the southern borrow pit in Field 6 (16,000m 3 ) and the northern borrow pit in Field 6 (40,000m 3 ) to reduce the tidal prism of the site and protect landfilled waste from erosion. This will be done using locally sourced material and up to 1,500m 3 of imported clean sandy clay fill. Stripping of an estimated 26,000m 3 of topsoil from approximately 7.8 ha of partly buried shingle ridges in Fields 4, 5 and 6 to expose shingle and restore vegetated shingle habitat in the long term, with careful management and grazing practices. Excavation of an estimated 32,000m 3 of soil and clay (to a typical depth of 500mm) from an area of approximately 5.3 ha in Fields 1 and 2 to create wet grassland, ponds and ditches, together with enhancing a further 3 ha of former borrow pits for nature conservation. Lowland meadow creation on areas of low fertility not used for creating intertidal, shingle, lagoon or wet grassland habitat. It is expected that the scheme would be split into two phases with earthworks done between 1 August and 28 February (to avoid the bird nesting season) and construction of the culverts and outfall subsequently. The following options were considered during the development of the scheme but were eliminated on environmental, technical or cost grounds: (a) Do Nothing (b) Managed Realignment (unconstrained breach) (c) Different culvert configurations (d) Different ways of passing water through the Western Sheet Piling (e) Partial or complete removal of landfilled waste from the site (f) Complete infilling of both borrow pits in Field 6 Consultation Consultation has been undertaken with internal Environment Agency functions and external stakeholders. Issues identified by consultees as being of concern include: Optimising habitat creation Archaeological potential ii

3 Sediment eroded from the site Navigability of the River Rother Consent requirements Waste handling and encapsulation Site management including grazing Avoiding disturbance to breeding and wintering birds Enhancing recreational amenity Implications for Pett Frontage sea defences Saline intrusion Environmental Impacts and Mitigation Geology, Soil and Hydrogeology Soil stripping may affect the structure of shingle ridges but overall the impact will be positive. There is likely to be an impact on the salinity of groundwater locally and possible change to the salinity of surface water features such as Nook Drain and adjacent water bodies. Increased salinisation of groundwater is unlikely to affect water bodies north of Nook Drain such as Long and Narrow Pits, which are used as fishery lakes, firstly because groundwater within the site is not in direct contact with tidal surface water and secondly because Nook Drain will intercept landward flows from the new saltmarsh area. Monitoring of water level and salinity change within both surface water and groundwater will be undertaken before, during and after the schemes implementation to confirm this. The existing waste landfill will be protected and covered in situ to prevent contact by people or animals. Geomorphology The proposed managed realignment will restore the intertidal character of part of Rye Harbour Farm that existed prior to There is unlikely to be a significant effect on the tidal flows in the Rother Estuary. The scheme will be managed to avoid an increase in flood risk to adjacent areas. Water The main potential impacts on water quality arise from creek erosion. Creek erosion will increase volumes of sediment entering the estuary, but the worst case estimate amounts to only 5% of the volume already in the estuary which is unlikely to have any significant effects. In the long term, saltmarsh creation will act as a sediment sink. Air, Noise and Climate Piling will be required for outfall construction which will have a temporary noise impact on visitors to Rye Harbour Nature Reserve. No other significant impacts are anticipated. iii

4 Flora and Fauna The project will create significant ecological enhancements in the form of new salt marsh (approximately 10.8 ha), brackish to saline lagoons (approximately 2.6 ha, possibly increasing to 5 ha subsequently), ponds and wet grassland (approximately 8.3 ha), lowland meadow (approximately 1.5 ha) and restored shingle ridge habitat (approximately 7.8 ha). Species that will benefit include breeding birds such as yellow wagtail, redshank, oystercatcher and little tern; wintering birds such as whimbrel and other waders, twite, shore lark, snow bunting and corn bunting; reptiles and amphibians; water voles; and invertebrates. The possibility of adverse impacts during construction on birds, badgers, reptiles and water voles has been identified and mitigation measures identified. The future management of the site will be integrated with that of Rye Harbour Nature Reserve to form an integrated ecological system. Fisheries Rye Bay is an important commercial fishery and the main fishing fleet is based at Rye Harbour. The ecological productivity of the new intertidal habitat will benefit fisheries as saltmarsh provides a good fish nursery habitat. Any adverse effects during construction and creek erosion following realignment are expected to be minor. Land Use Rye Harbour Farm was formerly in agricultural use until it was acquired by the Environment Agency in 2003, since when it has been managed for nature conservation. Defra classifies the land as Grade 3 (good to moderate quality). Surrounding land uses are residential, tourism (including a caravan park and car park), recreation (including angling lakes and a sailing club) and nature conservation (Rye Harbour Nature Reserve). There will be disruption to recreational access during construction but footpaths on the Farm will be kept open (with management of vehicle crossings by banksmen) or diverted, rather than being closed. The main long-term impact is the conversion of about 31 ha of former farmland to intertidal and other coastal habitats and the enhancement of recreational amenity. These are beneficial impacts. Landscape and Visual Amenity The scheme will be beneficial to the landscape as a whole as it will replace improved grassland with seminatural features. This will allow the site to link better with local and regional natural characteristics. The new outfall structure does create a negative effect on the landscape, though this can be minimised through design; i.e. avoiding vertical elements that can be seen from a long distance. The impact of the outfall structure is minimal, relative to the whole site and the benefits of the scheme. Changes in view from properties will be minor. The most significant negative effect is that caused by the construction period. This particularly impacts the properties along The Ridge and on Frenchman s Beach Caravan Park. This effect is temporary yet substantial. A number of mitigation measures have been identified. iv

5 Human Beings There will be some disruption during construction, principally temporary footpath closures during earth moving. The most extensive works will take place during the period August to February. Safety measures such as fencing will be put in place to avoid risk to the public. Permanent effects will include the creation of new recreational assets and footpath enhancement. Overall the project will represent a significant benefit. Archaeology and Cultural Heritage No known archaeological features or deposits would be adversely impacted by the proposed works. In view of the site history, the potential for discovering unknown sites is considered to be limited. In case any are found, an archaeological tool box talk will be conducted before the contractor starts excavation work and archaeologists will be brought in to examine any finds that are made. Traffic and Transport Access to the site during both construction and operation will be via the road through Rye Harbour village. The project will achieve a balance of excavated and required material, so large numbers of vehicle movements outside the site during construction will be avoided. The traffic impact on the surrounding network will be for a short period of time and the adverse impacts would be minor. After construction, the existing car park at Rye Harbour will serve the site. Rye Harbour Nature Reserve already receives about 200,000 visitors per year. It is not known whether this number will increase in response to habitat enhancement on Rye Harbour Farm but it is unlikely that there would be a substantial impact of traffic on the road to Rye Harbour, which is a heavily trafficked road serving industrial estates as well as the village. No effects are anticipated on navigability in the River Rother. Natural Resources The re-use of excavated material within the site to fill borrow pits will minimise waste, quarrying and road transport. Environmental Enhancements The scheme provides the following enhancements: Contribution towards the Environment Agency s achievement of non-statutory Biodiversity Action Plan targets. Contribution towards recreation and access targets. v

6 In addition to the core projective objectives, a number of additional enhancements have been identified. These all involve earth moving and it will be cost-effective to undertake then while earth moving equipment is on site for soil stripping and filling the borrow pits: The footpath between Fields 5 and 6, between Quarry and Ternery Pools and the secondary defence bund, will be enhanced by widening and levelling it to make it wheelchair accessible. Features such as gently sloping banks and shallow berms will be created along Nook Drain to make it more interesting as a habitat, especially to water voles. Enhancement works may include creation of areas of wet reedbed attached to Nook Drain and planting of suitable marginal species, providing additional suitable habitat of benefit to water vole. This will only be undertaken in areas where existing water vole burrows would not be disturbed. The old pond at the end of Nook Drain will be re-created. A new ditch will be created, replacing an existing fence line. Pits in Fields 2 and 3 will be enhanced to have locally deeper water and islands. Ditches in Field 2 will be reprofiled. Reedbed in Field 3 will be extended. The landfill cover will not be topsoiled but retained as low fertility subsoil and seeded with a wild flower meadow mix. Soil will be stripped from the interface of shingle ridges and the intertidal area in order to create a saltmarsh / vegetated shingle ecotone, which is a particularly rare habitat for which considerable potential exists at Rye Harbour Farm. vi