Reinstatement of the Thames & Severn Canal at Roundhouse Farm

Environmental Statement

Rev 1.2 9th November 2011

Environmental Statement - T&S Canal Roundhouse Farm Page 1 of 24 Reinstatement of the Thames & Severn Canal at Roundhouse Farm Marston Meysey

Environmental Statement

Contents Page

1. Introduction 3

2. Description of Development 5

3. Environmental Considerations 7

3.1 Flood Risk Assessment (including drainage strategy) 7

3.2 Archaeological Statement of Significance/Heritage Assessment 13

3.3 Landscaping Master-plan 16

3.4 Transport Statement 18

3.5 Ecology 21

3.6 Public Footpaths 22

Appendix 1: Pre-application advice and comment

Appendix 2: Report of Archaeological Evaluation

Appendix 3: Ecological Appraisal

Appendix 4: Roundhouse Farm Quarry Planning Conditions

Appendix 5: Cotswold Canals Restoration Phase 2 Environmental Impact Assessment

Environmental Statement - T&S Canal Roundhouse Farm Page 2 of 24 Environmental Statement - T&S Canal Roundhouse Farm Page 3 of 24 1. Introduction

The 36 mile canal link between the Rivers Thames and the Severn opened in 1789 and remained in use until other forms of transport caused its decline and closure. The eastern and central sections of the Thames & Severn Canal, which include the length at Roundhouse Farm, officially closed in 1927.

The land, which at the time was owned by County Council, was sold or given to the adjacent landowners. Although there were covenants protecting the integrity of water conveyance along the route, these were increasingly ignored and some sections became infilled. The section at Roundhouse Farm is thought to have been ploughed in (i.e. flattened) about 50 – 60 years ago.

The public interest in saving the nation's surviving but threatened canal system, which started in the 1940s, grew to the point that already closed canals started to attract enthusiasts which then formed canal restoration societies. The forerunner to the Cotswold Canals Trust started in the early 1970s and has become the largest canal restoration society in the UK.

The restoration of the Cotswold Canals (the T&S Canal and the Stroudwater Navigation) is now recognised as one of, if not the, most important canal restoration schemes in the UK. The Cotswold Canals Project Board comprises a wide range of organisations including all the riparian Local Authorities (including ), the Canal & River Trust (the successor to British Waterways), the Environment Agency, Natural , The Trust, The Cotswold Canals Trust, the Inland Waterways Association and many others.

Wiltshire County Council and North Wiltshire District Council along with Cotswold District Council, District Council and Gloucestershire County Council all put in place planning policies that protected the route and generally supported restoration. 's Core Strategy 53 is a current manifestation of this.

When proposals emerged for aggregate extraction at Roundhouse Farm, The Cotswold Canals Trust and many others successfully made representations that the canal should be reinstated at the end of any quarrying at the site and this was embodied in a S.106 requirement. This appeared as Condition 39 in the first (N.00.1105) minerals consent and subsequent ones relating to the site.

Condition 39 states:

“Unless otherwise agreed in writing by the minerals planning authority, within 12 months of the commencement of the development on site, details regarding the proposed programme of restoration works to be carried out in relation to the Thames & Severn Canal shall be submitted to the Director of Environmental Services for approval.”

The other conditions relating to planning consent N.00.1105 can be found in Appendix 4.

The pre-application advice provided by the Council in regard to this current application outlines the current rather unsatisfactory situation with regard to ongoing issues with Condition 39. See Appendix 1.

Environmental Statement - T&S Canal Roundhouse Farm Page 4 of 24 One of the reasons given why Condition 39 cannot currently be implemented is that a separate planning application would be needed to cover the reinstatement of the canal itself rather than it being a detail for the post quarrying restoration plan. This application seeks to overcome this issue.

An Environmental Impact Assessment (Appendix 5) has been undertaken for the section of the Cotswold Canals, known as Phase 2, which runs from the Thames at Inglesham in the east to Wildmoorway Lower Lock near the Gateway Centre in the west.

Environmental Statement - T&S Canal Roundhouse Farm Page 5 of 24 2. Description of Development

The development comprises the reconstruction of the Thames & Severn Canal across Roundhouse Farm; a distance of about 1km. For the most part, this follows the original line of the canal. There is a southern deviation to avoid the section which forms part of the Roundhouse residential property where development has been allowed which obstructs the original route.

Fig 1: Extract of the site location plan

Fig 2: Canal Route across Roundhouse Farm

Environmental Statement - T&S Canal Roundhouse Farm Page 6 of 24 The canal reinstatement will fall short of Meysey Brook at the western end of the site. This gap will provide plenty of flood conveyance pending a future separate plan for the canal crossing and reconnection with the extant canal towards Eysey.

The new canal bed will be formed of clay and the profile has been designed with gentle sloping sides so that it can use the type of clay found beneath the aggregate layer on site and in the surrounding area. Although the width of the central navigation channel will be the same as the original, the shallower sides will result in a wider overall width and, importantly, the resulting wider reed fringed edges will have greater value to wildlife. The use of a thicker clay lining will make the canal more secure from leakage if it becomes inhabited by water voles.

Due to the limited thicknesses of the natural gravels, the clay lining of the original canal may or may not have created blockages to groundwater flows in places. The new channel is designed not to block groundwater conveyance under the canal. This is achieved by either leaving a layer of the underlying aggregate in place or by replacing it by a permeable layer or by excavating into the underlying clay layer and replacing it with gravels or other permeable materials.

Fig 3: Canal design including groundwater conveyance

The southern canal bank will eventually carry the Thames & Severn Way, a long distance trail that will link the Thames Path with the Severn Way. On the northern side between the roundhouse and the C117 leading to Castle Eaton, the canal bank will carry the diverted Marston Meysey Footpath 10 Public Right of Way which formerly crossed the site prior to the quarrying.

The new canal bed cannot be re-watered immediately as an isolated stretch. This will occur when connectivity is achieved as part of the wider restoration of the canal. All aspects of this are covered in the accompanying Environmental Impact Assessment.

Environmental Statement - T&S Canal Roundhouse Farm Page 7 of 24 3. Environmental Considerations

3.1 Flood Risk Assessment (including drainage strategy)

3.1.1 Introduction

This is a study of the impact on flooding and on land drainage (surface water conveyance in ditches) of the proposed restoration of the profile of a canal across the Roundhouse Farm site. Note that it is not intended to restore a working canal at this stage, merely to demonstrate that the necessary earthworks do not pose a significant additional risk of flooding.

The site is currently a partially restored gravel working which was carried out by the Moreton C Cullimore Group. Before gravel extraction began in 2006 the site was almost flat agricultural land. The original Thames & Severn canal had largely been filled in and its banks destroyed, although parts would have been visible. West of the Meysey Brook, which forms the western boundary of the site, the canal is extant if somewhat dilapidated. East of the site the route of the canal is visible for a short distance but has largely been flattened and subsumed by agriculture.

One parcel of private property remains, roughly at the centre of the site, the eponymous Roundhouse. Development at this house precludes routing the canal entirely along its original line, and a deviation is necessary to the south of the property, as shown in attached drawing RFH-01

Drawings RFH-01, RFH-02 and RH-03 submitted with this application show the proposed route, sample cross-sections of the proposed restored canal and a long section along the line of the canal.

3.1.2 Groundwater

The original mineral extraction proposals proposed that the canal corridor would be preserved, thereby also preserving the band of gravel beneath the canal, allowing passage of groundwater. With the corridor revised to loop south of the Roundhouse, there may be some risk that the aquifer has become truncated here. Recent proposals from GWP Consultants1 show three 'transfer ditches' crossing the line of the canal. These would have to be formed as inverted siphons although the flow in them is likely to be so low that sediment traps will need to be incorporated at each end.

1 GWP Consultants LLP Updated Hydrological, Hydrogeological and Flood Risk Assessment for Roundhouse Farm, Marston Meysey. Prepared for Moreton C Cullimore Group 24 August 2017

Environmental Statement - T&S Canal Roundhouse Farm Page 8 of 24 3.1.3 Flood Frequency

The Environment Agency Flood Map shows that the site is mostly within Flood Zone 3, characterised by a flood risk of 1 in 100, an Annual Exceedance Probability, AEP, of 1% or greater. This is because of the proximity of the R. Thames and the Meysey Brook. Part of the north of the site is situated within Flood Zone 2, with a probability of flooding less than 1 in 100 years but greater than 1 in 1000 years (AEP of 0.1%).

Cullimores commissioned a study by GWP consultants2 in 2014 which concludes that the band of ground between the canal and the R. Thames is liable to flood with a frequency of 20% AEP, and that the flood risk to the north of the restored canal remains at an AEP of 1%.

3.1.4 Flood Storage

The new available storage on this site is 117,239m3 (GWP 2014 Report, Table 1) following extraction and restoration to a series of ponds and reed beds. The volume 'lost' to the canal banks, raised to a suitable operating level of +77.2mAOD, is 61,700m3, giving a net gain in flood storage over the situation before mineral extraction began equal to 117,239 - 61,700 = 55,539m3.

3.1.5 Flood Conveyance

Two north to south drainage ditches currently cross the line of the canal. It appears from old maps that this was the original arrangement, and because of the relative canal and ground levels it is likely that, historically, they ran beneath the canal in inverted siphons.

The western ditch, known as the Village Drain, currently crosses the line of the canal in a 450mm diameter culvert. This ditch will be diverted parallel with the canal on its northern side, to discharge into the Meysey Brook.

Similarly, the eastern ditch currently crosses the line of the canal in a 450mm diameter pipe which will be replaced by a new siphon pipe.

The additional inverted siphons to be provided for groundwater transfer (see the Groundwater paragraph above) will also provide connectivity of the flood plain north and south of the canal, assisting with drainage of the northern area.

3.1.6 Flood Flows within the Canal

Excess water within the finally restored canal would be discharged at an existing overflow weir just west of the Marston Mesey Brook, which the canal would cross by an aqueduct.

2 GWP Consultants LLP Hydrological, Hydrogeological and Flood Risk Assessment Assessment for Roundhouse Farm, Marston Meysey 24 October 2014

Environmental Statement - T&S Canal Roundhouse Farm Page 9 of 24 3.1.7 Conclusions

There will be net increase in the available floodplain storage within both the northern and southern site areas compared to the situation before mineral extraction began.

The conveyance capacity and elevation of the two existing ditches will be maintained

Three additional culverts will be provided to mitigate any possible aquifer truncation for: Cotswold Canals Trust J Beatty MSc Ceng MCIWEM

Environmental Statement - T&S Canal Roundhouse Farm Page 10 of 24 Environmental Statement - T&S Canal Roundhouse Farm Page 11 of 24 Environmental Statement - T&S Canal Roundhouse Farm Page 12 of 24 Environmental Statement - T&S Canal Roundhouse Farm Page 13 of 24 3.2 Archaeological Statement of Significance / Heritage Assessment

3.2.1 Historic Environment

This chapter considers the potential effects of the restoration of the Thames & Severn Canal across the Roundhouse Farm site. These are considered in sufficient detail to address the pre-application advice provide by Wiltshire Council regarding the Archaeology and Impact to Heritage Assets.

3.2.2 Background to the Site

The site has a long history of human activity as evidenced within the extensive Archaeological Field Study carried out by the Oxford Archaeological Unit prior to the site gaining permission for the extraction of aggregates (see Appendix 2). This study covers the whole area where it is intended to restore the canal including the short diversion away from the original route which will pass to the south of the Roundhouse property.

The archaeological investigations found evidence of human activity from early prehistoric periods onwards.

The Archaeological Field Study focuses on the early history of the site with little focus on the canal which is the subject of this application.

The Thames & Severn Canal was was constructed between 1783 and 1789 and formed the first inland waterway link between the Rivers Thames and Severn. The route followed at Marston Meysey is typical of the eastern section in that it runs parallel with the local rivers with banks sufficiently high to protect the canal from frequent flooding.

The alignment would have been chosen to enable the banks to be created from the material excavated between them. The banks of the canal are therefore usually raised above the surrounding ground with the base of the channel below it. The canal at Roundhouse Farm was constructed in the gravel beds and was clay lined to prevent leakage.

The canal operated from its opening in 1789 until the early part of the twentieth century. Although the last known through passage took place in 1911, it is thought that the eastern section was still navigable into the 1920s, although poorly maintained. This section was formally abandoned in 1927.

At some point about 60 years ago, the canal was effectively levelled by reversing the original method of construction and returned to land to agricultural use. There is no evidence that material from elsewhere was imported to infill the canal.

Following representation by the Canal Trust and many others, a planning condition of the Minerals planning consent for aggregate quarrying at Roundhouse Farm was that:

“Within one month of this permission being implemented details regarding the proposed programme of restoration work to be carried out in relation to the shall be submitted for approval. Development shall be carried out in accordance with the approved details.”

Environmental Statement - T&S Canal Roundhouse Farm Page 14 of 24 This Condition 39 has never been properly enforced and remains extant. The main motivation for this current application is to remove the constraint that the reconstruction of the canal cannot proceed due to it not having a planning consent.

The route of the canal has been protected from aggregate extraction and the diversion route around the Roundhouse property passes through the area designed to prevent quarrying close to that dwelling.

3.2.3 Baseline Assessment

A significant proportion of the route of the canal was used for one of the haul roads used to move aggregates around the site.

The original construction of the canal would have disturbed any older artefacts along its route.

Some of the original puddle clay forming the base of the original canal is expected to be found still in place but is likely to have been badly damaged by tree roots and/or burrowing animals. It has minimal heritage value.

The only section of potentially undisturbed ground is the area through which the reconstructed canal is proposed to pass south of the Roundhouse property.

3.2.4 Archaeological Survey

The Archaeological Field Study carried out by the Oxford Archaeological Unit (see Appendix 2) was carried out in anticipation of the whole of the Roundhouse Farm site being quarried. This detailed investigation covered the area where the canal deviates from its original course south of the roundhouse.

Quarrying has subsequently taken place over the vast majority of the Roundhouse Farm site.

Following such an extensive survey, it is suggested that any further investigations are unnecessary.

Environmental Statement - T&S Canal Roundhouse Farm Page 15 of 24 3.2.5 Eisey Copse Field Scheduled Ancient Monument

The presence of the Eisey Copse Filed Scheduled Ancient Monument ref: 1003255 has been flagged in the pre-application advice. This is located to the south west of the Roundhouse Farm site (see plan below).

At its closest point, the reconstructed canal will be following more or less its original route to eventually meet up with the extant canal which follows the edge of, but outside, the SAM. A physical connection across Meysey Brook is not included in this application.

The reconstruction of the canal is assessed to have a negligible impact on the SAM.

3.2.6 Post Development Assessment

The reconstructed canal will eventually form an important part of the restored Cotswold Canals link between the rivers Thames and Severn.

In doing so, it will help further the objectives of Wiltshire Council's Core Strategy 53, which encourages canal restoration, as well an enabling the sustainable future for all of the heritage assets associated with the canal.

It will improve public access into the area and through this, a greater appreciation of the historic environment.

Environmental Statement - T&S Canal Roundhouse Farm Page 16 of 24 3.3 Landscaping Masterplan

The post development landscaping included within this ES applies to the reconstructed canal only. All of the surrounding land forms part of the Roundhouse Farm Quarry site which has its own Landscaping Masterplan. That Masterplan has not generally taken into the account the landscaping of the canal itself even though its reinstatement is covered by Condition 39.

It is therefore likely that the presence of the reinstated canal will require changes to that plan in order to be consistent, or were that plan to be implemented in the absence of the canal, further changes will be required along the route of the reinstated canal.

During the reconstruction works, machines will be present on site to carry out the work but this will be temporary and the impact small compared with the much wider spread and intense quarrying that has been undertaken at Roundhouse Farm and indeed other nearby sites over a period of many years.

The reinstated canal will form a linear feature in the landscape in its own right, as it did previously for almost two centuries before it was destroyed. It will form a continuation of the surviving canal landscape feature to the west and, in due course will be continued east of the site towards Kempsford and beyond.

A seasonally dry section of the T&S Canal bed at Latton

Environmental Statement - T&S Canal Roundhouse Farm Page 17 of 24 The canal cannot be re-watered until further canal restoration takes place including the provision of an all year round reliable water supply. In the meantime, the canal bed is likely to remain largely empty but with a variable and generally quite low water level within it. This is likely to more or less dry up in the summer months but is likely to be sufficiently damp to support reed growth. This is a similar situation to much of the surviving original canal bed within the area.

From a canal restoration perspective, it is important that trees are not allowed to grow in the canal bed as their roots would damage and eventually breach the canal lining. The canal lining is thick enough to tolerate reeds and grasses. When the canal is re- watered to its operation depth, it may well be possible to transfer reeds growing in the centre of the empty bed to the upper parts of the banks which would then become permanently wet.

When viewed from a distance from either the adjacent roads or from the Thames Path which runs on the southern bank of the river which itself runs along the southern boundary of the Roundhouse Farm site, the canal will only form a subtle feature within the landscape and will tend to blend in with the adjacent reedbeds which are a legacy of quarrying.

Users of the diverted Marston Meysey Footpath 10 public right of way, which runs along the northern bank of the canal, will have a good view of both the largely empty canal bed and eventually the fully restored canal. The heavy use of the canal towpath between Latton and South Cerney demonstrates that the use these types of paths is valued by the public.

The eventual establishment of the Thames & Severn Way in the form of a multi-user trail along the towpath following the southern bank of the canal will provide a linear link running right across the Cotswold Water Park from Lechlade through to Siddington near and beyond to , Stroud and the Severn.

The residual impacts of the restored canal are considered to be positive in a Local context.

Environmental Statement - T&S Canal Roundhouse Farm Page 18 of 24 3.4 Transport Statement

The section of canal to be restored on the site of the remediated gravel workings is 1km in length.

The actual work to reinstate the canal, will require: 1. Removal of material from the line of the canal to form the canal bed 2. Placement of excavated material along either side of the canal channel to form the towpath and retaining banks 3. Disposal of surplus excavated material 4. Lining of the canal channel with clay to produce a water tight channel

There are several potential techniques for achieving the above and the amount of material that needs to be transported depends on which is used.

The method requiring least material movements would involve excavating out all of the material above the underlying clay, which largely comprises gravel and sand but with potentially some of the remains of the original canal bed mixed in with it, and place it to one side. The quantity of clay needed to line the canal would be excavated from the top of the underlying clay. The excavated shallow hole in the top of the clay layer would be backfilled with the material previously excavated from above the clay. The outer canal banks would be formed from the same material, locally derived clay or imported inter fill material. The canal would be lined with the excavated clay derived previously mentioned to form a water tight canal bed with the gravel layer placed under the canal providing groundwater conveyance. This technique is expected to result in a relatively small deficit of available material which would need to be supplemented with imported inert fill or surplus material from elsewhere on site. (See diagram on page 12).

The more likely technique would involved the removal of the overlying aggregates but either retaining or placing a layer for groundwater conveyance. The surplus aggregate would then be removed from site and the canal reconstructed using a combination of clay for the lining and imported inert fill and/or more clay for the outer banks. This technique or a slight variation of it, is the most likely option if the canal is to be reinstated under Condition 39 of the Roundhouse Quarry consent.

Environmental Statement - T&S Canal Roundhouse Farm Page 19 of 24 The following is considered to represent the worst case:

Impact of construction works

Activity Quantity m3 1. Excavate canal channel 51,000 2. Construct retaining banks and towpath 13,600 3. Surplus material to be removed from site (1-2) 37,400

4. Clay to line canal channel brought to site 48,500

Total material to be moved to/from site (3+4) 85,900

These materials will be moved on/off site via the current (and to be retained) access point to the site on the C124 Kempsford road, approx. 500m east of the junction with The Street (to Marston Meysey).

If this option has been lost due to events subsequent to the quarrying activity ceasing at Roundhouse Farm, access to the road network would be at the site of Crooked Bridge where the line of the canal meets the C117 Castle Eaton Road which connects to the C124.

To put this into perspective, the consented quarrying works at the Roundhouse Farm site, comprehended total material movements an order of magnitude larger than those generated by the worst case proposed canal restoration as shown below.

Consented quarry works 3 Quantity m3 1. Extracted mineral from quarry 687,842 2. Imported fill for restoration 227,848

Total material to be moved to/from site (1+2) 915,690

Construction Works Summary

The total vehicle movements on the public highway to restore the canal, represent a 9 percent increase over those currently consented for quarry working at the Roundhouse Farm site, and present only minimal impact over current or recent site activity and that at neighbouring mineral quarrying sites.

Post Construction Traffic Assessment

Upon completion of the construction works, the road traffic generated by visitors to this section of canal or in connection with its maintenance is expected to be minimal.

The reinstated canal bed initially resulting from the proposed development will be isolated at its western end by Meysey Brook. The footpath, Marston Meysey 10, on the north bank east of the roundhouse is the diversion of a right of way that pre-existed and is primarily of local value.

3 Source: David Jarvis Associates report for M C Cullimore Ltd dated 22.1.2010

Environmental Statement - T&S Canal Roundhouse Farm Page 20 of 24 The aspiration is for this section of canal to form part of the wider restoration of the canal from the Thames at Inglesham to South Cerney and eventually beyond. As part of this, the Thames & Severn Way would pass along the southern bank and boating traffic will be generated.

The diversion of the the Thames and Severn Way is expected to increase pedestrian visits to the area as they use the towpath. This will have consequential benefits for establishments that cater for their needs such as the public houses at Kempsford and Castle Eaton and the wider range of facilities in and Lechlade.

However the amount of additional local road traffic generated by such activities is expected to be small with a negligible impact.

It is not anticipated that the the canal at Roundhouse Farm would, of itself, generate boating related road traffic as boat users will be visiting the area by boat having started from elsewhere.

The implications of the of the wider canal restoration project are addressed in the Environmental Impact Assessment.

3.5 Ecology

An Ecological Appraisal undertaken by AD Ecology Ltd is provided in Appendix 3.

It concludes that the proposed canal restoration if implemented without appropriate mitigation could have adverse impacts on nesting birds, and if habitats develop further before construction commences could adversely impact upon Roman Snails. These adverse impacts, if they occur, are considered to be ‘significant’ in a Local context.

Mitigation is proposed to address nesting birds and Roman Snails; the matters of concern. The nesting bird mitigation is standard practice. In the case of the Roman Snails, it may prove difficult to maintain a 5m wide strip of bare earth to prevent them entering the affected area. However, the alternative mitigation approach using surveys and, if necessary, licensed removal to nearby suitable habitat can be undertaken.

With regard to residual effects, the Appraisal concludes that the proposed canal restoration does not affect any designated nature conservation sites or protected/notable habitats. The restoration of the canal can be implemented in such a way to protect nesting birds and Roman snail.

The restored canal and adjacent corridor will support a range of habitats, including local biodiversity priority habitat, which expand and complement habitats currently found in the restored quarry. The habitats will allow a variety of wildlife, including notable species already present on-site, to use the canal corridor post-restoration. The residual impacts of the restored canal are considered to be positive in a Local context.

Environmental Statement - T&S Canal Roundhouse Farm Page 21 of 24 3.6 Public Footpaths

A diversion to the former route of the Marston Meysey 10 public footpath forms part of the works associated with the Roundhouse Farm quarrying activities and its site restoration. Part of the new route will follow the northern bank of the canal to form east of the Roundhouse property to the C117 Castle Eaton road (see map on next page).

It is likely that the vertical elevation of the ground will be raised to form the canal bank. The level top of the bank itself will be wide enough to carry a 2m wide footpath and will be surfaced with a layer of gravel or other suitable self draining material to provide surface over the underlying bank which may be comprised of clay or other materials prone to cause a muddy surface if not treated.

At present, there is no right of way along the route of the southern canal bank of the canal, unfortunately that was extinguished many years ago. However, it is hoped that this will eventually be used to carry the Thames & Severn Way, a long distance trail that will link the Thames Path with the Severn Way. It may become heavily used once established. It is also likely to be a multi-user trail as has happened where the canal has been restored towards its western end. Here the towpath has been surfaced with a 2m wide and quite substantial hard wearing stone based surface to cater for the high levels of use now encountered. The use of the towpath around Ebley near Stroud is only exceeded by the Cotswold Way in the .

Environmental Statement - T&S Canal Roundhouse Farm Page 22 of 24 Environmental Statement - T&S Canal Roundhouse Farm Page 23 of 24 A section of the resurfaced towpath east of Stroud - work carried out by volunteers

The Appendices are provided as separate documents.

Compiled by:

Ken Burgin BSc.

Cotswold Canals Trust [email protected]

Environmental Statement - T&S Canal Roundhouse Farm Page 24 of 24