SECTION 7 LANDSCAPE RESTORATION

Transcription

1 SECTION 7 LANDSCAPE RESTORATION 27

2 7. Landscape and Restoration This section should be read in conjunction with Drawing No.CO8194/A010 Rev. B, Regeneration Strategy As Proposed which can be found at Section Design Mitigation proposals The restoration and ecological mitigation of Newbridge has commenced and will continue as progressive regeneration and mitigation measures throughout the projected 20 year working life of Newbridge and Twinyeo - where mitigation works have also commenced with the creation of new 5m wide planted bund hedges as mitigation for those to be removed as part of the works. Early ecological mitigation works across the site will include; provision of suitable bat and bird boxes and artificial otter holts and the ongoing management of existing retained hedges, woodland and grassland Following cessation of quarrying in year 20+, further significant enhancement and ecological regeneration / mitigation will take place to promote the local ecology, bio-diversity and in particular; bat foraging and flight routes, invertebrates and reptiles. In this period, it is proposed to create within the worked out Newbridge and Twinyeo pits a new Lake. The profile and shores of this lake to be created using exclusively existing Newbridge backfill, or Twinyeo site won material The Lake water level will be passively maintained at an 8m AOD level and will have an approximate total volume of 4.75Mm3.In conditions of flood, (assumed to be a once in 100 year flood plus 20% allowance for climate change), the proposed Newbridge Pit Lake will afford a degree of flood alleviation to both the River Bovey and the River Teign. A flood alleviation volume of approximately 531,000m3 / 117M Gallons may be achieved - giving a maximum temporary Lake water level of 10m AOD. Following recession of the event, there would be controlled release of flood waters downstream into the Bovey and Teign Sections of the rivers Bovey and Teign adjacent to Twinyeo and bisecting Newbridge have been highlighted by Natural England to be of SSSI quality for their invertebrate assemblage and as a potential river site to notify. An ecological site investigation has identified as the most important feature of the Twinyeo site, its hedges, forming bat flight corridors Where hedgerows and trees are to be lost to quarrying, suitable replacement bat flight routes, in the form of linear 5m wide planted 28

3 bund hedgerows, have been and will be provided to ensure alternative routes and foraging areas for both bats and badgers. In addition, retained existing boundary hedges and tree lines will be enhanced or "strengthened" to a minimum width of 5m in the form of bunds, to be densely planted with locally indigenous tree and shrub species Marginal aquatic habitat will be created; as gently sloped and stepped areas around the Lake edge and as a flooded plain to the south of the Lake. A wooded Island is to be created at +10m AOD level within the Lake's flooded plain to provide a safe wildfowl breeding ground and to promote reptiles. Wet grassland habitat will be enhanced and created on the existing wet grassland floodplain land between the Lake and the River Bovey to the south east. Localised shallow depressions will be used as a basis for ephemeral ponding and marshy grassland habitat. The intention would be to encourage the establishment of Culm grassland species Where possible grazing areas will be established around the edge of the proposed lake. The existing grazed and managed grassland areas are to be retained and incorporated into the overall site management provision. A further new hedge enclosed area of Culm grazing land is to be created on the proposed southern lake peninsular outcrop. Proposed grasslands are to be carefully managed to achieve a species rich sward An extension to the existing southern permissive route will be created with the intention to give; pedestrian, cyclist and horse rider access around the west and north of the proposed lake. 7.2 Restoration Techniques Site slopes are to be regraded using existing backfill or site won material to achieve long-term stable profiles. The restoration landform is to be constructed in accordance with the strategy plan Materials would comprise insitu materials to be re-graded. Consequently, the importation of material is not anticipated Restoration materials only to be handled whilst in a dry and friable condition, and during periods of dry weather. Care should be taken to avoid double handling. 7.3 Planting Operations Generally 29

4 7.3.1 Plant handling and planting techniques would be in accordance with the relevant clauses of the CPSE guidelines (Horticultural Trades Association,1985). The upper layers of the restoration substrate would be loose tipped and graded using a back actor or similar plant to avoid compaction/tracking of the restoration surface Plant species and stock to be in accordance with those specified in Table 1 and the following specifications Wet / Damp Woodland Planting Proposed trees shall be 45 to 60cm bare root transplants and shall be notch planted into the substrate at nominal 1.5m centres on an irregular grid to achieve a more natural appearance. A slow release fertiliser would be incorporated into the substrate around the base of each plant Hedgerow Planting Proposed trees/shrubs shall be notch planted into previously constructed hedgebanks - "bunds". Plants to be arranged in two alternate rows approximately 450mm apart at a rate of 5 plants per linear metre. Care to be taken to ensure a thorough mix of species throughout each hedgerow. As with woodland planting, a slow release fertiliser would be incorporated into the substrate within the planted rows Seeding The use of commercially available seed is not intended. Rather, grassland seed would be collected from existing grassland within the site. Such donor swards would receive prior management to ensure maximum diversity and to eradicate unwanted weed species. In the absence of a suitable sward at the site, an alternative donor sward would be sought locally. Collected seed to be broadcast across all newly restored areas at a rate of 25g/m to ensure early vegetation and protection of the open substrate from surface erosion Establishment of Marginal Aquatic & Wetland Habitat Natural regeneration of marginal gently sloping edges of newly established Lake would be encouraged. To augment this process, seed popogules from existing areas of Culm grassland within the site and/or 30

5 in the immediate vicinity would be harvested and utilised during the restoration and subsequent aftercare period Fencing Permanent stock-proof fences to surround all newly planted / seeded areas to prevent incursions Establishment of Grassland/Scattered Scrub Habitat In order to maximise potential ecological interest at the site some areas of grassland would be permitted to gradually become colonised by coarse grassland/herb/scattered scrub species. However, care would be taken during the aftercare period to maintain an open sward with a diverse physical structure Establishment of Damp/Culm Grassland In low-lying areas and around the rim of the Lake, Culm species would be encouraged to colonise areas of flat terrain and/or damp hollows. To aid this process, seed popogules from existing areas of Culm grassland within the site and/or in the immediate vicinity would be harvested and utilised during the restoration and subsequent aftercare period 7.4 Aftercare Woodland All newly established woodlands to be subject to a five year aftercare period, during which time plants would be maintained at around 95% of their original planted numbers. All planting positions to be treated with a suitable herbicide and/or strimmed to control emergent weed growth to establish a competitor free zone of 0.5m radius around the base of each plant Grasslands All grasslands would be inspected for signs of surface erosion and emergent weed problems and any necessary remedial measures undertaken. In open grassland habitats colonisation of the sward by scrub/tree seedlings would be controlled by grazing and/or hand pulling/cutting. In coarse grasslands where scattered scrub is to be allowed to establish, a program of rotational cutting would be implemented to ensure the sward develops a diverse structure Hedgerows As with newly established woodlands, hedgerows to be subject to a five year aftercare period, during which time plants would be maintained at around 95% of their original planted numbers. Planted rows to be treated with a suitable herbicide and/or strimmed to control emergent 31

6 weed growth. Hedgebanks / bunds to be inspected and any necessary remedial measures / repairs undertaken Marginal Aquatic & Wetland Habitats Lake to be maintained free of tree and scrub species, and any emergent weed problem controlled by cutting and/or the application of a suitable aquatic herbicide. Established reeds to be cut to the ground every two years, and any silting of proposed ponds or marginal habitats to be remedied by limited rotational dredging during winter months to avoid excessive disturbance of the wetland flora and fauna Slopes Table 1 The site to be monitored for indications of slope instability and any remedial necessary measures undertaken. WOODLAND AND HEDGEROW SPECIES Wet / Damp Woodland Species %mix Oak (Quercus robur) 20 Ash (Fraxinus excelsior) 15 Alder (Alnus glutinosa) 20 Willow (Salix caprea) 15 Hawthorn (Crataegus monogyna) 10 Hazel (Corylus avellana) 10 Blackthorn (Prunus spinosa) 10 Hedgerows Species %mix Oak (Quercus robur) 20 Ash (Fraxinus excelsior) 15 Hawthorn (Crataegus monogyna) 15 Hazel (Corylus avellana) 15 Blackthorn (Prunus spinosa) 10 Guelder Rose (Viburnum opulus) 5 Dog Rose (Rosa canina) 5 32