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PROPOSED DEVELOPMENT 3 Wrights Pit North PROPOSED DEVELOPMENT 3 Wrights Pit North SLR Consulting Limited SLR Consulting Limited
APPENDIX 3/1
Wrights Pit North
APPENDIX 3/1
Wrights Pit North SLR Consulting Limited SLR Consulting Limited
3.1 This section of the Planning Application & Environmental Statement (PA&ES) provides information on the development proposals, including the proposed method of infilling, the timescale required and a description of the restoration landform to be implemented.
3.2 It is proposed to continue waste disposal operations for a further 5 years plus 1 year for restoration beyond the currently permitted dates at a projected input similar to existing.
3.3 The Department of Infrastructure recognises that quantities of permitted material will require a disposal route during this period and the site exists as a contingency for this specific purpose. All imported material will remain within the conditions of the existing Waste Management License (WML) (i.e will comprise mixed inert and C&D wastes, including asbestos and plasterboard, and within the input limits specified) and waste operations and management of the site will remain as per existing. The continuation of a facility that has the capability and capacity to accept problematic wastes such as asbestos and plasterboard enables the Department of Infrastructure to continue to meet its obligations in provision of a disposal facility for wastes which cannot be recycled or incinerated.
3.4 The projected inputs and increased timescale will however necessitate an amended alternative restoration scheme and this is included within this planning application. On completion of the proposed development an additional area of land, previously impacted by mineral working, will have been restored to a beneficial after use.
3.5 This proposal therefore seeks the following:
3.6 The site, which currently receives inert and mixed construction and demolition waste (including asbestos and plasterboard), operates under planning permission Ref: PA09/02058 which requires landfill and restoration operations to cease by 31st December 2014 (refer to Appendix 1/1 for copy of planning consent). The proposed development seeks planning permission to allow for the continuation of landfilling operations at Wright's Pit North for a
further 3 years until the 31st December 2019, plus 1 year until 31st December 2020.
3.7 The proposals also seek implementation of an amended alternative restoration scheme to reflect the projected volume of imported materials over the amended life of the site.
3.8 The current proposals are for continuation of existing operations which includes importation of inert and mixed construction and demolition waste (including asbestos and plasterboard) over the proposed 5 year time period for operations to 2019.
3.9 The site does not, and will not, accept either household (black bag) waste or incinerator bottom ash.
3.10 The approved working plan for the site (under planning consent PA09/02058) divided the site into two phases, Cell 1 (on the west of the site) and Cell 2 (on the east).
3.11 Since landfilling operations commenced in 2004 the majority of waste has been placed in the eastern phase where levels have been restored to approximately 6.5m AOD. Infilling of the eastern phase was completed in 2006 and the area of the site graded into the surrounding contours to create sustainable slope profiles. The eastern phase of Wrights Pit North was subsequently restored in 2006 all in accordance with the approved scheme and no further working will take place within this area.
3.12 It is proposed that waste would continue to be deposited in the western area (Cell 1) of Wright's Pit North; the current base of the cell being approximately 3m AOD at its lowest point, as shown on the site survey (see Drawing WPN 2/2).
3.13 The additional waste would be deposited over a period of 5 years with material concentrated towards the northern part of Cell 1 as shown in Drawing WPN 3/1 – 'Top of Waste Profile' and tapering off to the south. This will ensure that site operations take place at a lower level and so benefit from the screening provided by the current landform; this would limit the visual impact of the operations on the surrounding area. As per the current permitted scheme it is proposed that the material contained in the bund on the western boundary will also be used in the restoration of the western phase to ensure that an acceptable final landform is achieved.
3.14 Condition 3 of the existing planning permission requires that the site be capped with layers of sand and gravel to allow for the free drainage of rainfall
and the free emission of landfill gas. This will remain the case for the proposed development. In addition Condition 5 of the current planning consent requires that no water or contaminants shall flow or be tracked by vehicle wheels on to the highway. Given the low lying nature of the site it is considered that any run-off will be retained within the site however, as per existing operations, vehicles will be monitored and action taken if material is being tracked to the site entrance and highway.
3.15 In all other respects site operations will remain as per the current planning consent and waste licence.
3.16 Hours of operation and access route will be as per those currently permitted.
3.17 In terms of the restoration landform, it is proposed that the final gradients and maximum heights reflect those found in the surrounding landscape. As a consequence, the majority of gradients on the alternative landform are similar to the permitted restoration scheme for the site and generally do not exceed 1:7. In terms of the maximum height of the restoration landform, Wrights Pit North would not exceed the level of neighbouring land. This is consistent with current planning consent and planning conditions for the site.
3.18 One of the key characteristics of the landscape surrounding the application site is the presence of the beach ridge topography. Similar features were constructed on top of the restored eastern phase of Wrights Pit North, thereby extending the adjacent natural beach ridge system. As the western phase of Wright Pit North will comprise low level restoration it is not proposed to include the 'beach ridge' features on the restoration landform design at this stage however this approach will be reviewed regularly as the site progresses towards completion. This was the same approach adopted for the current approved scheme and is therefore considered acceptable.
3.19 This section describes the proposed form and method of revised restoration of the landfill at Wrights Pit North. The overall design concept has evolved to achieve a number of key objectives:
3.20 In particular, it is envisaged that the existing landfill and excavation would be restored to a range of habitats including gallic heath, species diverse grassland and dune slack habitat in keeping with the surrounding landscape.
3.21 The design for the restoration of Wrights Pit North has been informed by the findings of the Landscape and Visual Assessment in Section 7 of the 2006 Environmental Statement and a recent visual assessment carried out as per of these proposals, and by experience obtained in the restoration of other landfills in the immediate vicinity including Ballacallow and Wrights Pit East.
3.22 Since landfilling operations commenced in 2004 the majority of waste has been placed in the eastern phase. In 2006 no further waste was placed in the eastern phase and that area of the site was graded into the surrounding contours to create sustainable slope profiles. The eastern phase of Wright's Pit North was subsequently restored in of 2006 in accordance with the approved scheme.
3.23 Levels in the western phase (Cell 1), where smaller quantities of waste have been placed, are approximately 3.5m AOD at the lowest point. As described above the cell is being progressively filled from north to south; it is proposed to continue this method of infilling for the waste which is the subject of this planning application.
3.24 Following completion of disposal operations existing site infrastructure would be removed in accordance with the approved programme (i.e. following completion of waste disposal operations) with the perimeter fence being removed and the underlying ground reinstated following the completion of restoration works in 2020.
3.25 The restoration substrate would comprise a suitable free-draining sandy substrate of low fertility. The restoration material would be imported from the neighbouring sites. In order to ensure their suitability, all restoration materials would be tested to verify their structure, organic content, pH and fertility.
3.26 Initially, restoration materials would be placed over the top of the covered waste to an average depth of 700mm. This means that the restoration substrate would be up to 1.2m thick. A thin layer (approximately 100mm) of
topsoil, stripped from adjacent land would then be placed on top of the restoration substrate.
3.27 "Topsoil materials" shall comprise of all that material which is deemed by the Landscape Architect / Engineer to be suitable. "Topsoil materials" shall be a Sandy loam of good crumb structure to pH 5-5.5 (BS 1377-3), Organic matter 15–20%, minimum index values for nitrogen, phosphorus, potassium and magnesium to be as for general purpose grade of BS 3882 including no stones over 50mm in any dimension. On visual inspection soils would be free of fragments and roots of aggressive weeds, sticks, straw, subsoil, pieces of brick, concrete, glass, wire, large lumps of clay or vegetation, and the like.
3.28 It is intended that the placement of topsoil materials would be undertaken in one lift to the finished thickness of 100mm; and that construction plant does not travel over areas where topsoil is placed and that placement operations do not compact or in some other way alter the nature of the topsoil materials.
3.29 The free draining nature of the substrate, coupled with the proposed restoration gradients would ensure adequate drainage and/or run-off of surface water across a large proportion of the site.
3.30 As identified in the Landscape and Visual Impact Assessment in Section 7 of this PA&ES, the existing landscape in the vicinity of the application site is exposed and typified by dunes and open undulating gallic heathland. The restoration proposals provides for the re-establishment of approximately 2.7 hectares of a grassland/heath/dune slack mosaic.
3.31 The restoration of Wights Pit North to a heathland / grassland mosaic will require the use of specialised techniques, which have been refined through practical experience of restoration at Ballacallow and Wrights Pit East. In addition, the site will need to be managed in the long term to ensure that the objectives for the restoration in terms of its visual appearance and ecology are realised.
3.32 The main elements can essentially be broken down into the following:
3.33 In order to stabilise the mineral substrate, and to provide a suitable microclimate for the germination of heather seedlings, around 4g/m2 of grass would be sown, before the heathland seed is applied, the nurse species will be mainly comprise of Deschampsia flexuosa; however, the precise species mix would be agreed with DEFA.
3.34 The location of the heathland donor site and methodology of harvesting would be agreed with DEFA prior to commencement. The brash and seed would be collected between late October and January of the following year; the donor site will be monitored in order to determine when there is sufficient viable seed available on the plants. The brash and seed would be collected from the donor site using specially adapted equipment to reduced damage to retained heathland and underlying soils. The work will be carried out by an experienced contractor.
3.35 The area from which the brash will be cut from is estimated at 1.7 hectares, while the restored area on the western section of the application site is approximately 2.7 hectares. This will allow a ratio of donor area to restored area of at least 1:2, allowing for some contingency should ground conditions restrict access. The heathland brash will be cut in radial bands; potentially between previously cut areas leaving adequate strips of undisturbed heathland between. The strips of undisturbed heathland would serve to shelter the adjacent areas to assist regeneration.
3.36 Heathland brash may be ‘chopped’ using specialist equipment to improve its suitability for distribution. In order to accelerate the germination of heather seedlings the seed will be milled to break the testa.
3.37 The seed would be sown using a specialised drill. Seeding work will be carried out in the week following seed collection, at a rate of approximately 20g/m2. The seed will be positioned at a depth of between 5 and 15mm below the surface, and were possible rolled to ensure good contact between the seed and the substrate. After sowing, the brash material will be spread across the site to provide an additional seed source and microclimate for establishment.
3.38 The heathland brash will be applied to the restored area at a 1:2 ratio (i.e. for every sq.m cut from the donor site this will be applied to a 2 sq.m area on the restored area). Where possible the brash would be then compressed into the surface with a light weight roller
3.39 A Soil Stabilisation Blanket (SSB) has been included not only to protect the side slopes of the restored area but also hold the heathland brash in place. Use of SSBs will also assist the re-vegetation of these areas, reducing the need for future operations where surface traffic would be to the detriment of establishing plants. The SSB will be placed immediately following the application of heathland brash so as to ensure that consistent coverage is maintained.
3.40 The SSB would only be placed on steeper slopes within the restored area i.e. those which exceed 1:7 however such slopes are not typical. The SSB would be held in place by being buried in an anchor trench of at least 200mm depth at the top and bottom of the slope, with a series of 8mm gauge 300mm length pins driven in at 0.5m centres along overlapping joins (overlap to be at least 10cm). Some cutting of the material may be required to allow the material to follow the curved corners of the side slopes.
3.41 Post and wire boundary fencing would be installed to protect the new heathland during the initial period of its establishment. This fencing will be maintained in good order throughout the aftercare period, and will only be removed once the heathland has become fully established.
3.42 The success of the proposed restoration would rely, to a large extent, on the continued management of the site and establishing habitats. Consequently, the restored site would be subject to a ten year aftercare period during which time the key aftercare priorities would include:
3.43 Aftercare operations would be undertaken over a series of four visits per year, and would be informed by the findings of the annual ecological monitoring regime.
3.44 In order to ensure the highest standards of implementation the landscape works and maintenance programme would be undertaken by a competent specialist landscape contractor and would be managed using JCLI landscaping and maintenance contracts¹. Both contracts would be managed by a Chartered Landscape Architect with experience of similar projects.
3.45 Baseline surveys of the site, previously restored areas and adjacent undisturbed gallic heathland have been undertaken (refer to Section 8 and Appendix 8/1) and these would be compared with surveys on newly restored land on an annual basis. In this way it will be possible to see how the diversity of the new heathland gradually increases. It will also be possible to assess any management problems – such as the presence of certain invasive weeds – in detail, so that an appropriate management regime can be put in place.
3.46 The proposed development is essential to ensure that the Government can demonstrate that it is making adequate provision to manage waste that cannot be recycled or incinerated. The amendment to the time period for operation of Wright's Pit North landfill is therefore considered to be in accordance with the requirement of the Island's Waste Management Plan to ensure that adequate landfill capacity is provided on a regular and contingency basis.
3.47 Whilst it has been necessary to revise the permitted restoration landform to take account the proposals for additional material being placed in the western half of Wrights Pit North, the proposed landform will enable the restoration works at the site to be progressed and the void infilled towards original levels. The proposed restoration landform follows the approved principals for the site, as does the restoration scheme and methodology, and when implemented, will allow opportunities for enhancing the anticipated ecological
¹ JCLI Agreements for Landscape Works and Maintenance Works, February 2002 revisions of 1998 edition) Wrights Pit North 3-8 SLR Consulting Limited
value of the site through the incorporation of a broader range of ground conditions and habitats.
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