«LONDONWEST MIDLANDS ENVIRONMENTAL STATEMENT Volume 2 | Community Forum Area report CFA7 | Colne Valley November 2013 ES 126.96.36.199 VOL LondonWest Midlands ...»
9.3.17 Recreational receptors, also with a high sensitivity to change, are located on PRoW throughout the study area, including the Grand Union Canal PRoW as well as users of the Canal, Denham Waterski Club and HOAC. Views from the Grand Union Canal are generally channelled views along the canal corridor. Views from Denham Waterski Club and the HOAC are typically of large expanses of water enclosed by lakeside vegetation.
9.3.18 People travelling on main roads, particularly those using Harvil Road and Moorhall Road, have a low sensitivity to change. Views are characterised by glimpsed views CFA Report – Colne Valley/No7 | Landscape and visual assessment
Future baseline 9.3.19 A summary of the committed developments which are assumed to be built and occupied prior to either the construction or operation of the Proposed Scheme is provided below, along with the consequential effect on the character of LCA and nature of views. Developments which will introduce new visual receptors which may be significantly affected are also described. These developments are shown on Maps CT-13-011 to CT-13-013a (Volume 5, Cross Topic Appendix 1 Map Book).
Construction (2017) 9.3.20 A planning application has been granted for mineral extraction, infilling with waste and restoration to agriculture at Denham Park Farm, Denham Green, Buckinghamshire. The quarry will be most prominent from Old Shire Lane PRoW and Tilehouse Lane and will appear in more distant views from Harefield. The development will have a local influence within the agricultural landscape adjacent to the M25. A temporary road to Denham park farm quarry site will also be a prominent raised feature within the rural landscape. During construction therefore, there will be the potential for a combined visual influence of the Proposed Scheme and the quarry site, although the scale of the Proposed Scheme construction will be considerably larger.
Operation (2026) 9.3.21 The application at Denham Park Farm is for mineral extraction with a licence to operate for twenty years. Active extraction will still be underway by 2026. Proposed planting along the A412 Denham Way/North Orbital Road and Tilehouse Lane will help filter views from the east. The existing Nockhill, Juniper and Halings Woods and the proposed woodland planting will screen views from the south towards the quarry site. There will be potential views of the quarry from Old Shire Lane PRoW and Tilehouse Lane overbridge.
Temporary effects arising during construction 9.4 9.4.1 As is commonplace with major infrastructure works, the scale of the construction activities means that works will be visible in many locations and will have the potential to give rise to significant temporary effects which cannot be mitigated practicably.
Such effects are temporary and vary over the construction period depending on the intensity and scale of the works at the time. The assessment of landscape and visual effects has been based on the activities occurring during the peak construction phase, which is defined as the period during which the main civil engineering works will take place, including establishment of compounds, main earthworks and structure works.
The effects associated with the peak construction phase in this area will generally be considered to be long term given the construction programme (see Section 2.3).
Overall, civil engineering works in this area will be undertaken between the start of 2017 and the end of 2025. The Colne Valley viaduct main compound will be in place for
CFA Report – Colne Valley/No7 | Landscape and visual assessment this and the porous portal hood into the surrounding landscape and to provide noise and visual attenuation; and presence of construction compounds within this area as identified in Section 2.
Avoidance and mitigation measures 9.4.3 Measures that have been incorporated into the draft CoCP to avoid or reduce
landscape and visual effects during construction include the following (see Volume 5:
maximising the retention and protection of existing trees and vegetation where possible (draft CoCP Section 12.2);
use of well-maintained hoardings and fencing (draft CoCP Section 5.6);
designing lighting to avoid unnecessary intrusion onto adjacent buildings and other land uses (draft CoCP Section 5.4);
replacement of any trees intended to be retained which may be accidentally felled or die as a consequence of construction works (draft CoCP Section 12.2);
appropriate maintenance of planting and seeding works and implementation of management measures, to continue through the construction period as landscape works are completed (draft CoCP Section 12.4); and temporary bunds will be positioned to screen views to the route construction.
9.4.4 These measures have been taken account of in the assessment of the construction effects below.
Assessment of impacts and effects 9.4.5 Prominent changes to landscape character and viewpoints during construction will relate to the temporary presence of construction plant and the removal of existing landscape elements, such as trees, hedges and agricultural land. Changes will be most notable within and around the Colne Valley where the Colne Valley viaduct will be constructed. Extensive earthwork profiling adjacent to the M25 and Chiltern tunnel southern portal will result in a notable change in the landscape. The height of the construction plant and viaducts and the close proximity of construction activities coupled with the absence of intervening screening (apart from the site hoardings and temporary earthwork bunds) will result in significant visual effects during construction. The topography in certain locations and the retention of intervening hedgerows and trees will partially screen low level construction activity.
Landscape assessment 9.4.6 The following section describes the likely significant effects on LCA during construction. All LCA within the study area considered to experience a non-significant effect (minor adverse or negligible) are described, Volume 5 Appendix LV-001-007 Part 4.
Harefield Farmlands Valley Slopes LCA 9.4.7 The Colne Valley viaduct will be 3.4 km in length and approached by a 190m long section of embankment. These elements will introduce large scale construction activity and substantially alter the character area, within an otherwise relatively secluded environment. The proposed Colne Valley viaduct and south embankment satellite compound, Ickenham auto-transformer feeder station satellite compound, roadhead and associated plant will be located on the southern side of this embankment and will introduce prominent elements that will impact the setting of the area. Three of the buildings of HOAC which will lie directly beneath the viaduct, will be demolished. The access road from Harvil Road to Dew’s Farm will be used as a construction access road introducing higher frequencies of traffic. Dew’s Farm and associated outbuildings will also be demolished. The removal of the existing overhead power line, pylons and the erection of new diversion route will result in the removal of areas of vegetation. The Colne Valley will be improved by a large section of overhead power line and pylons being removed. To the east of Harvil Road across to Breakspear Road South within CFA6, a large area of land will be used for segment casting and a sustainable placement area. This will introduce prominent elements into the urban fringe. To the south of South Harefield, a substantial area will be used by National Grid as the construction compound for the overhead power line diversion and feeder station.
9.4.8 To the northern side of the Chiltern Main Line embankment sections of hedgerows and woodland block will be removed to accommodate the Proposed Scheme, weakening the enclosed character of the immediate area. The large scale of construction and associated plant and frequency of construction traffic will reduce the tranquillity within this area.
9.4.9 Taking the above into account, the introduction of new elements will markedly alter the tranquillity of the LCA. There will be the addition of new features and components that substantially alter the character and setting. Therefore the magnitude of change is considered to be high.
9.4.10 The high magnitude of change, assessed alongside the high sensitivity of the character area, will result in a major adverse effect.
Colne River Valley LCA 9.4.11 During construction of the Colne Valley viaduct, lakeside vegetation will be removed opening up the land between individual water bodies. In addition a jetty will be positioned within the lakes to enable the piers of the viaduct to be constructed. This construction activity will be at odds with existing land use and adversely affect the character of the valley. The construction of the viaduct spanning the Colne Valley will reduce tranquillity. The two Colne Valley viaduct jetty storage satellite compounds on Moorhall Road will be present within this area and accessed from it. The Colne Valley viaduct and south embankment satellite compound will be accessed from Harvil Road.
This will lead to an increase in construction traffic and plant activity within these areas. The overhead power line and pylons that currently traverse the Colne Valley will be temporarily diverted to the west of the existing alignment during construction.
Overall, construction activity will introduce large scale construction elements within CFA Report – Colne Valley/No7 | Landscape and visual assessment the landscape, markedly altering the tranquillity of the area and will result in a high magnitude of change.
9.4.12 The high magnitude of change, assessed alongside the high sensitivity of the character area, will result in a major adverse effect.
Colne Valley LCA 9.4.13 A short section of the viaduct and a 290m long embankment will be constructed in the north of the LCA where the Colne Valley viaduct laydown satellite compound, the Colne Valley viaduct north launch satellite compound and associated plant will all be located. This will result in large areas of vegetation and agricultural fields being lost and the introduction of construction activity. An access route will be formed from the A412 Denham Way/North Orbital Road to the Colne Valley viaduct north launch satellite compound. Vegetation removal will be required alongside waterways within the Colne Valley to accommodate the Colne Valley viaduct and Colne Valley north embankment. There will be the addition of prominent features such as the viaduct within the setting. The River Colne diversion will involve the removal of an area of vegetation and the introduction of construction activity. These activities will alter the tranquillity of the character area.
9.4.14 As this construction activity will be confined to the northern edge of the LCA and will be largely screened by existing surrounding woodland, the overall magnitude of change is assessed as medium.
9.4.15 The medium magnitude of change, assessed alongside the high sensitivity of the character area, will result in a moderate adverse effect.
Colne Valley Gravel Pits LCA 9.4.16 This LCA setting will not be directly affected by the construction of the Proposed Scheme, with activities taking place within the adjoining Maple Cross, Colne River Valley and Colne Valley LCA. The addition of new features that will impact landscape character will include extensive earthworks in Maple Cross Slopes South LCA, the construction of the viaduct and removal of lakeside vegetation within Colne River Valley LCA and the removal of vegetation, earthworks and construction of the Heathrow spur within the Colne Valley LCA. Aspects of these construction works will be perceptible in neighbouring LCA from within the Colne Valley Gravel Pits LCA.
9.4.17 Construction activity in adjacent LCA will noticeably affect the existing tranquillity of this LCA. Taking this into account, the magnitude of change is considered to be medium.
9.4.18 The medium magnitude of change, assessed alongside the high sensitivity of the character area, will result in a moderate adverse effect.
Maple Cross Slopes South LCA 9.4.19 Construction activities within the southern part of this LCA will include the Colne Valley viaduct north embankment satellite compound and construction of the Tilehouse Lane overbridge and the temporary access road to Denham Park Farm quarry site. The Colne Valley viaduct north embankment satellite compound and associated plant will be a prominent feature to the north, close to the M25. The CFA Report – Colne Valley/No7 | Landscape and visual assessment compound will be accessed from the A412 Denham Way/North Orbital Road. The Colne Valley viaduct main compound will also be located in the LCA, with access from Chalfont Lane and via the temporary M25 slip roads for HGV traffic. The Chiltern tunnel main compound will also be accessed from Chalfont Lane. Lighting will be used throughout the night at these construction compounds, contributing to a reduction in the tranquillity of the LCA. Temporary overnight workers accommodation will be located within the Colne Valley viaduct main compound.
9.4.20 Removal of sections of hedgerow will result in a change to the character of the landscape as field boundaries will become more open, although the majority of Old Shire Lane mature hedgerows will be retained. The construction of the access track to Denham Park Farm quarry will reduce impacts to the mature Old Shire Lane hedgerow as far as practicable.
9.4.21 The Denham Park Farm quarry will have a cumulative effect on the LCA during construction.
9.4.22 The topography of agricultural fields will be substantially altered with the introduction of material associated with the tunnel excavation. Earthworks profiling will be prominent with material graded between 3m and 5m high.
9.4.23 Construction will cover a large part of the LCA reducing both visual and audible tranquillity. The addition of these construction elements will substantially alter landscape character through the introduction of elements that will markedly alter the tranquillity of Maple Cross Slopes South LCA. Therefore the magnitude of change is considered to be high.
9.4.24 The high magnitude of change, assessed alongside the medium sensitivity of the character area, will result in a major adverse effect.
Chalfont St Peter South LCA 9.4.25 Direct impacts upon the LCA will be confined to the distribution of excavated material adjacent to the M25. Elements of construction will be audible and visible from the northern edge of the LCA, introducing unfamiliar elements at odds with existing landscape character and decreasing levels of tranquillity.
9.4.26 Construction works within the LCA and the adjoining Maple Cross Slopes South LCA will be audible. Whilst woodland blocks in the south of the LCA will isolate much of the construction activity to the north, there will still be a notable reduction in tranquillity as a result of the works. The future development at Denham Park Farm quarry site and the associated temporary access road will further reduce tranquillity in the vicinity of the works. The Proposed Scheme will be set within the context of these mineral workings.
9.4.27 Given the presence of general construction activity, cranes and significant earth moving activities relating to the earthworks this will result in the introduction of elements which substantially alter the character of the setting. Therefore the magnitude of change is considered to be high.
9.4.28 The high magnitude of change, assessed alongside the medium sensitivity of the character area, will result in a major adverse effect.