Biomethane (Castle Eaton) Limited Castle Eaton AD Plant Extension and Upgrade
Flood Risk Assessment
882120-R1(02)-FRA
DECEMBER 2020
RSK GENERAL NOTES
Project No.: 882120-R1(02)-FRA Site: Castle Eaton AD Plant upgrade and extension Title: Flood Risk Assessment Client: Biomethane (Castle Eaton) Limited Date: December 2020 Office: Wigan Status: Issue
Technical Author K Jackson reviewer C Whittingham
Signature Signature
Date: December 2020 Date: December 2020
Project manager C Whittingham Project Director D Conway
Signature Signature
Date: December 2020 Date: December 2020
Date Reviewed Approved Issue No Version/Details Author issued by by - Internal Review 23.09.20 KJ CW CW 00 Draft for client comment 25.09.20 KJ CW DC 01 Updated draft 01.12.20 KJ CW DC 02 Issue 17.10.20 KJ CW DC
RSK LDE Ltd (RSK) has prepared this report for the sole use of the client, showing reasonable skill and care, for the intended purposes as stated in the agreement under which this work was completed. The report may not be relied upon by any other party without the express agreement of the client and RSK. No other warranty, expressed or implied, is made as to the professional advice included in this report. Where any data supplied by the client or from other sources have been used, it has been assumed that the information is correct. No responsibility can be accepted by RSK for inaccuracies in the data supplied by any other party. The conclusions and recommendations in this report are based on the assumption that all relevant information has been supplied by those bodies from whom it was requested. No part of this report may be copied or duplicated without the express permission of RSK and the party for whom it was prepared. Where field investigations have been carried out, these have been restricted to a level of detail required to achieve the stated objectives of the work.
RSKThis Environmentwork has been undertaken in accordance with the quality management system of RSK LDE Ltd. Castle Eaton Farm AD Plant extension and upgrade Flood Risk Assessment 882120-R1(02)-FRA
CONTENTS
1 INTRODUCTION ...... 1 1.1 Context ...... 1 1.2 Scope of work ...... 2 2 SITE DESCRIPTION ...... 4 2.1 Existing Site ...... 4 2.2 Planning History ...... 7 2.3 The Proposed Development ...... 9 3 LEGISLATION, POLICY AND GUIDANCE ...... 10 3.1 National Policy ...... 10 3.2 Local Policy ...... 11 3.3 Area Guidance ...... 12 3.4 Site-specific consultation ...... 13 4 SOURCES OF FLOOD RISK ...... 16 4.1 Criteria ...... 16 4.2 Flooding from rivers (fluvial flood risk) ...... 16 4.3 Flooding from the sea (tidal flood risk) ...... 17 4.4 Flooding from the land (overland pluvial flood risk) ...... 18 4.5 Flooding from groundwater ...... 19 4.6 Flooding from sewers ...... 20 4.7 Other sources of flooding ...... 21 5 FLOOD MITIGATION MEASURES ...... 23 5.1 Overview ...... 23 5.2 Overland flood flow ...... 23 5.3 Finished floor levels ...... 23 5.4 Safe access/egress ...... 23 5.5 Environmental Permit/Ordinary watercourse easement and consents ...... 23 5.6 Groundwater ...... 24 6 PLANNING CONTEXT ...... 25 6.1 Application of planning policy ...... 25 6.2 Land use vulnerability ...... 25 6.3 Sequential Test ...... 25 7 SURFACE WATER DRAINAGE STATEMENT ...... 27 7.1 Scope ...... 27 7.2 Proposed surface water drainage strategy ...... 27 8 CONCLUSIONS AND RECOMMENDATIONS ...... 29
RSK Environment i Castle Eaton Farm AD Plant extension and upgrade Flood Risk Assessment 882120-R1(02)-FRA
APPENDICES APPENDIX A RSK GROUP SERVICE CONSTRAINTS APPENDIX B DEVELOPMENT PROPOSALS APPENDIX C SWINDON LLFA CORRESPONDENCE APPENDIX D CURRENT DRAINAGE ARRANGEMENT
RSK Environment ii Castle Eaton Farm AD Plant extension and upgrade Flood Risk Assessment 882120-R1(02)-FRA
1 INTRODUCTION
1.1 Context
1.1.1 This Flood Risk Assessment (FRA) has been prepared on behalf of Biomethane (Castle Eaton) Limited (the ‘client’). The assessment is in support of the full planning submission for the upgrade and extension of an existing Anaerobic Digestion (AD) facility, located at Castle Eaton, SN6 6JX (the ‘site’).
1.1.2 The assessment has been prepared in accordance with the National Planning Policy Framework (NPPF)1 and its accompanying Planning Practice Guidance2, the Interim Code of Practice for Sustainable Drainage3, BS 8533-2011 Assessing and Managing Flood Risk in Development Code of Practice4, BS 8582:2013 Code of practice for surface water management for development sites5 and the Non-statutory technical standards for sustainable drainage systems6, with site-specific advice where relevant from the Environment Agency, the Lead Local Flood Authority (LLFA), the Local Planning Authority (LPA) and the client.
1.1.3 The NPPF sets out the criteria for development and flood risk by stating that inappropriate development in areas at risk of flooding should be avoided by directing development away from areas at highest risk, but where development is necessary, making it safe without increasing flood risk elsewhere.
1.1.4 The key definitions within the PPG are:
• “Flood risk” is a combination of the probability and the potential consequences of flooding from all sources – including from rivers and the sea, directly from rainfall on the ground surface and rising groundwater, overwhelmed sewers and drainage systems, and from reservoirs, canals and lakes and other artificial sources; and • “Areas at risk of flooding” means areas at risk from all sources of flooding. For fluvial (river) and sea flooding, this is principally land within Flood Zones 2 and 3. It can also include an area within Flood Zone 1 which the Environment Agency has notified the local planning authority as having critical drainage problems.
1 Ministry of Housing, Communities and Local Government, ‘National Planning Policy Framework’, February 2019.
2 Ministry of Housing, Communities and Local Government, ‘Planning Practice Guidance - Flood Risk and Coastal Change, ID 7’, March 2014. http://planningguidance.planningportal.gov.uk/blog/guidance/flood-risk-and-coastal- change/ 3 DEFRA, ‘Interim Code of Practice for Sustainable Drainage Systems’ National SUDS Working Group, July 2004. 4 BSI, ‘BS 8533-2011 Assessing and managing flood risk in development Code of practice’, October 2011. 5 BSI, ‘BS 8582:2013 Code of practice for surface water management for development sites’, November 2013. 6 DEFRA, ‘Sustainable Drainage Systems - Non-statutory technical standards for sustainable drainage systems’, March 2015. Biomethane (Castle Eaton) Limited 1 Castle Eaton Farm AD Plant Upgrade and Extension Flood Risk Assessment 882120-R1(02)-FRA
1.1.5 For this site, the key aspects that require the assessment are:
• The Environment Agency’s indicative flood zone map shows that the site is located within Flood Zone 1 (Figure 1.1); and • The site boundary is approximately 5.5Ha therefore surface water drainage must be considered, and sustainable drainage systems (SuDS) should be incorporated where possible.
Figure 1.1: Environment Agency Flood Zone Map (accessed September 2020)
1.2 Scope of work
1.2.1 A key element of project development is to prepare a FRA to establish the flood risk associated with the proposed development and to propose suitable mitigation, if required, to reduce the risk to a more acceptable level.
1.2.2 The scope of work relating to a FRA is based on the guidance provided in Section 14 of the NPPF and its accompanying Planning Practice Guidance.
1.2.3 A site-specific FRA must demonstrate that the development will be safe for its lifetime taking account of the vulnerability of its users, without increasing flood risk elsewhere, and, where possible, will reduce flood risk overall. The scope of this assessment therefore comprises the following elements:
• To review architect plans, planning information and other studies to determine existing site conditions; • To obtain information on the hydrology and hydrological regime in and around the site;
Biomethane (Castle Eaton) Limited 2 Castle Eaton Farm AD Plant Upgrade and Extension Flood Risk Assessment 882120-R1(02)-FRA
• To obtain the views of the Environment Agency / LLFA including scope, location and impacts; • To determine the extent of new flooding provision and the influence on the site; • To assess the impact on the site from climate change effects and anticipated increases in rainfall over a 60 year period for commercial / agricultural uses; • To review site surface water drainage based on the proposed layout and, if necessary, to determine the extent of infrastructure required; and • To prepare a report including calculations and summaries of the source information and elements reviewed.
1.2.4 Reliance has been placed on factual and anecdotal data obtained from the sources identified. RSK cannot be held responsible for the scope of work, or any omissions, misrepresentation, errors or inaccuracies with the supplied information. New information, revised practices or changes in legislation may necessitate the re-interpretation of the report, in whole or in part.
1.2.5 The comments given in this report and opinions expressed are subject to RSK Group Service Constraints provided in Appendix A.
Biomethane (Castle Eaton) Limited 3 Castle Eaton Farm AD Plant Upgrade and Extension Flood Risk Assessment 882120-R1(02)-FRA
2 SITE DESCRIPTION
2.1 Existing Site
Location
Site Name and Address: Castle Eaton Farm, Castle Eaton, Swindon
Site National Grid Reference: (E) 414527; (N) 195066
2.1.1 The site boundary is approximately 5.8ha in size, and is located to the south of Castle Eaton. The site is currently used as an AD facility, and also encompasses some agricultural land and buildings, and an access track.
Table 2.1: Site setting
Direction Characteristic
The site is bounded to the north by agricultural fields and light North industrial units, with further agricultural fields, the village of Castle Eaton and the River Thames beyond.
East A farm access track with agricultural fields beyond.
Immediately bounded by agricultural fields with a large solar farm South beyond.
Immediately bounded by agricultural fields with wooded areas and West farmsteads beyond
2.1.2 Figure 2.1 shows a site location map.
Biomethane (Castle Eaton) Limited 4 Castle Eaton Farm AD Plant Upgrade and Extension Flood Risk Assessment 882120-R1(02)-FRA
Figure 2.1: Site location map
Land Use and Topography
2.1.3 The existing site is an existing AD facility and agricultural land, containing areas of hardstanding on the site with the inclusion of an access track.
2.1.4 The approximate land use of the site is as follows:
Table 2.2: Existing site land uses for the area outlined for development (5.5Ha)
Land use Area (Ha) Percentage (%)
Impermeable ~1.6 29
Permeable ~3.9 71
Total 5.5 100
2.1.5 From available LiDAR data (1m DTM 2019) the site is relatively flat with levels generally ranging from 81mAOD to 78mAOD. Due to the nature of the existing development, there are areas of raised ground in the northern section of the site above these levels associated with the stockpiles and the existing bunding. The southern site shows a gentle
Biomethane (Castle Eaton) Limited 5 Castle Eaton Farm AD Plant Upgrade and Extension Flood Risk Assessment 882120-R1(02)-FRA
fall from west to east from approximately 80.5mAOD on the western boundary to 78.9mAOD adjacent to the access track.
2.1.6 The LiDAR data for the site is shown in Figure 2.2 below.
Figure 2.2: Local ground elevations
Hydrology
2.1.7 Available OS mapping highlights an Ordinary watercourse originating approximately 220m to west of the development. The watercourse flows in a westerly / northerly direction towards the River Thames.
2.1.8 The River Thames / Isis (Main River) is located approximately 500m to the north of the site at its closest point, with the main channel approximately 620m to the north of the site.
2.1.9 The planning application (S/COND/12/1476) for the discharge of Condition 10 of the original approval (S/12/0317) for the anaerobic digestors noted a small drain running along the southern boundary of the existing site.
Geology
Desk Study
Biomethane (Castle Eaton) Limited 6 Castle Eaton Farm AD Plant Upgrade and Extension Flood Risk Assessment 882120-R1(02)-FRA
2.1.10 Based on the British Geological Survey7 online mapping for the area, the site exhibits the following geology:
• Superficial Geology: Summertown-radley Sand And Gravel Member - Sand And Gravel. Superficial Deposits formed up to 3 million years ago in the Quaternary Period. Local environment previously dominated by rivers (U). • Bedrock Geology: Oxford Clay Formation - Mudstone. Sedimentary Bedrock formed approximately 157 to 166 million years ago in the Jurassic Period. Local environment previously dominated by shallow seas.
2.1.11 BGS Borehole data records were searched for nearby borehole logs that may give relevant information regarding the on-site geology. No borehole records were located on- site. The closest borehole record available is located approximately 250m to the north of the site, BGS Reference: SU19NW31. The borehole record identified 0.2m of topsoil overlying mainly clayey sands and gravels of the Terrace Deposits to a depth of 1.7m. Beneath this lies strata of clays of the Oxford Clay formation to a maximum borehole depth of 3mbgl (below ground level). Groundwater was struck within the boreholes at depths of 1.2mbgl.
Hydrogeology
2.1.12 Hydrogeological information was obtained from the online Magic Maps service. Mapping shows the site is underlain by a ‘Secondary undifferentiated’ bedrock aquifer. The site is also underlain by a ‘Secondary A’ superficial aquifer.
2.1.13 The site is not located within a Groundwater Source Protection Zone (SPZ). The closest Groundwater SPZ is a ‘Zone II – Outer Protection Zone located approximately 850m north of the site.
2.2 Planning History
2.2.1 The planning history of the site and immediate surrounds are summarised in the below table:
Table 2.3: Planning History
Application no. Status Project Description
S/12/0317 Approved Construction of 2no. The development of an (Discharge of anaerobic digesters, plant Anaerobic Digestion Conditions room, feed and liquor tanks, Plant, which processes S/COND/12/1476) silage clamps, digestate purpose grown energy lagoon, amended entrance crops via digestion and hardstanding on Land at technologies into biogas Castle Eaton Farm Castle and agricultural Eaton Wiltshire SN6 6J. fertilisers.
7 British Geological Survey online mapping, available at http://mapapps.bgs.ac.uk/geologyofbritain/home.html?location=&gobBtn=go
Biomethane (Castle Eaton) Limited 7 Castle Eaton Farm AD Plant Upgrade and Extension Flood Risk Assessment 882120-R1(02)-FRA
Application no. Status Project Description
S/12/1515 Approved Variation of approved plans, Regularisation of ‘as under condition 11 of built’ elements of the previous permission Caste Eaton AD Plant. S/12/0317, for minor revisions to include replacement of feed hopper with a low sealed tank (2.3m high) and re-siting of technical building and associated plant.
S/AGRI/13/1081 Approved Prior Approval Notification for The installation of a the installation of a bunded digestate storage lagoon liquid slurry/fertiliser lagoon on land south of the for the storage of digestate on approved AD Plant to Land at Castle Eaton Farm facilitate the plant Castle Eaton Wiltshire SN6 processes. 6J.
S/14/1308 Approved Erection of an anaerobic The installation of a third digester and a grain storage digestor to increase the building on Land at Castle capacity of the existing Eaton Farm Castle Eaton Castle Eaton AD Plant. Wiltshire SN6 6J.
S/14/1309 Approved Installation of an anaerobic The installation and digestor gas conditioning and operation of a gas compression plant on Land at conditioning and Castle Eaton Farm Castle compression plant to Eaton Wiltshire SN6 6J. facilitate export of biomethane into the National Transmission System.
S/17/0717 Approved Retention of earth bund and Regularisation of 2m. high security fencing on landscaped earth bund Land at Castle Eaton Farm and security fencing Castle Eaton Wiltshire SN6 already installed at the 6J. Castle Eaton AD Plant.
S/17/0718 Approved Erection of carbon capture Installation of machinery plant and tanker filling point, for the purpose of retention of site office and capturing, storing and relocation of approved gas re-using carbon dioxide conditioning plant on Land at byproducts of the AD Castle Eaton Farm Castle processes. Machinery Eaton Wiltshire SN6 6J. includes cleaning and liquification equipment, 2no. storage cylinders and loading bay.
Biomethane (Castle Eaton) Limited 8 Castle Eaton Farm AD Plant Upgrade and Extension Flood Risk Assessment 882120-R1(02)-FRA
2.2.2 As demonstrated above, the primary planning permissions relating to the operation of the AD plant are S/12/0317, S/12/1515, S/14/1308 and S/14/1309 issued by Swindon Borough Council.
2.3 The Proposed Development
2.3.1 The proposed development seeks to incorporate the following additional main elements and modifications to the approved AD Plant. These proposed changes fall predominantly within the application boundary of the earlier permission (S/12/0317), with some areas extending southward onto adjacent land.
• Erection of 1no. additional digestor; • Removal of existing silage clamps and installation of replacement clamps; • Construction of an effluent lagoon for run off from the new silage clamps; • Construction of a rainwater lagoon; • Establishment of a new separation area and digestor offtake; • Upgrading and relocating 2no. existing feed hoppers; • Construction of a welfare/office building; • Erection of a flare stack; • Construction of a weighbridge; and, • Construction of a replacement gas upgrader unit/ network entry facility/ Carbon Dioxide (CO2) sequestration area.
2.3.2 The proposed development is driven by the need to upgrade the existing facility to meet current industry standards as well as to meet Environment Agency (EA) operational requirements. Furthermore, these improvements would make more efficient use of the available area, allowing for increased retention time of substrate in the digestion process and therefore increased gas yield, and enable future gas to grid connectivity.
2.3.3 Additionally, the incorporation of the gas upgrade plant will allow for the plant to export biogas into the NTS, thereby displacing natural gas. Fuel substitution in this way supports the de-carbonisation of the hard-to-reach sector of domestic cooking and heating, therefore supporting the UK’s legally binding target of achieving net zero by 2050.
2.3.4 Export to grid is also cleaner than the alternative of burning gas to generate electricity.
2.3.5 The proposed site layout is included in Appendix B.
Biomethane (Castle Eaton) Limited 9 Castle Eaton Farm AD Plant Upgrade and Extension Flood Risk Assessment 882120-R1(02)-FRA
3 LEGISLATION, POLICY AND GUIDANCE
3.1 National Policy
Table 3.1: National legislation and policy context
Legislation Key provisions
The aims of planning policy on development and flood risk are to ensure that flood risk is taken into account at all stages in the planning process to avoid inappropriate development in areas at National Planning risk of flooding, and to direct development away from areas at Policy Framework highest risk. (2019) Where new development is, exceptionally, necessary in such areas, policy aims to make it safe without increasing flood risk elsewhere and where possible, reducing flood risk overall.
Planning Practice The NPPF is supported by an online Planning Practice Guidance, Guidance (2014) which provide additional guidance on flood risk.
The Flood and Water Management Act (FWMA) aims to implement the findings of the 2007 Pitt Review and co-ordinate control of drainage and flood issues. Flood and Water There are a number of increased responsibilities within the Act Management Act that affect adoption of SuDS features and the role of the 20108 Environment Agency to expand on the mapping data they provide. The implementation of SuDS features has many beneficial impacts on the treatment of surface water during remediation works.
Section 24 – The Environment Agency is empowered under this Act to maintain and improve the quality of ‘controlled’ waters Water Resources Section 85 – It is an offence to cause or knowingly permit pollution Act 19919 of controlled waters Section 88 – Discharge consents are required for discharges to controlled waters
The Water Framework Directive (WFD) requires all inland and coastal waters to reach ‘good’ chemical and biological status by 2015. Flood risk management is unlikely to have a significant impact on chemical water quality except where maintenance works disturb sediment (such as de-silting) or where pollutants are Water Framework mobilised from contaminated land by floodwaters. Directive (2000)10 The main impact of the WFD on flood risk management, both now and in the future, relates to the ecological quality of water bodies. Channel works, such as straightening and deepening, or flood risk management schemes that modify geomorphological processes can change river morphology. The WFD aims to protect conservation sites identified by the EC Habitats Directive and
8 Flood and Water Management Act, 2010 9 Water Resources Act, 1991 10 EU Water Framework Directive, 2000 Biomethane (Castle Eaton) Limited 10 Castle Eaton Farm AD Plant Upgrade and Extension Flood Risk Assessment 882120-R1(02)-FRA
Legislation Key provisions
Birds Directive that have water-related features, by designating them as ‘protected sites’.
3.2 Local Policy
Table 3.2: Local policy legislation and policy context
Legislation Key provisions
‘Policy EN6: Flood Risk
A. The risk and impact of flooding will be minimised through: • directing development to areas with the lowest probability of flooding; • ensuring that all development addresses the effective management of all sources of flood risk; • ensuring that development does not increase the risk of flooding elsewhere including on adjoining and surrounding land; and • ensuring wider environmental benefits of development in relation to flood risk.
B. The suitability of development proposed in flood zones will be assessed using the Sequential Test, and, where necessary, the Exceptions Test. A sequential approach should be used at site level.
C. A site specific flood risk assessment will be required for Swindon Borough development proposals of one hectare or greater in Flood Zone 1 Local Plan (2026) and for all proposals for development (including minor adopted 201511 development and change of use) in Flood Zones 2 and 3 and Critical Drainage Areas, and also where proposed development or a change of use to a more vulnerable class may be subject to other sources of flooding. Appropriate mitigation and management measures must be implemented.
D. All development proposals must be assessed against the Local Flood Risk Management Strategy to address locally significant flooding including that affecting neighbouring authorities. Appropriate mitigation and management measures must be implemented.
E. All development shall be required to provide a drainage strategy. Developments will be expected to incorporate sustainable drainage systems and ensure that run-off rates are attenuated to greenfield run-off rates. Higher rates would need to be justified and the risks quantified. F. Sustainable drainage systems should seek to enhance water quality and biodiversity in line with The Water Framework Directive.
11 Swindon Borough Council (2015), Swindon Borough Local Plan 2026 Biomethane (Castle Eaton) Limited 11 Castle Eaton Farm AD Plant Upgrade and Extension Flood Risk Assessment 882120-R1(02)-FRA
3.3 Area Guidance
Table 3.3: Area Guidance
Study Overview of key provisions and policies
SFRA: The principle aim of the SFRA was to map all forms of flood risk in Swindon Borough order to provide an evidence base to locate new development. It Council Strategic also aims to provide appropriate policies for the management of Flood Risk flood risk and identify the level of detail required for site-specific Assessment Level FRAs. The SFRA contains information and maps detailing flood 1 sources and risks. Information relevant to the site is detailed in 201912 Section 4 of this report.
Preliminary Flood Risk Assessments are produced by Lead Local Flood Authorities (LLFAs) in England and Wales. A Preliminary Flood Risk Assessment (PFRA) is the first part of the planning cycle for flood risk management as set out in the Flood Risk Regulations (2009), which implement the requirements of the European (EU) PFRA: Floods Directive (2007). The EU Floods Directive aims to provide a Swindon Borough consistent approach to managing flooding across Europe. Council Preliminary The PFRA is organised by the River Basin District (in this case the Flood Risk Thames River Basin District) and produced by the LLFA (in this Assessment case Swindon Borough Council). The PFRA considers local 201113 sources of flooding that the LLFA is responsible for: ordinary watercourses, surface water, groundwater and sewers where flooding is wholly or partially caused by rainwater or other precipitation entering or affecting the system. Information is gathered from existing sources on past floods and flood models to identify Flood Risk Areas.
12 AECOM, Swindon Borough Council Strategic Flood Risk Assessment Level 1, May 2019 13 Swindon Borough Council, Preliminary Flood Risk Assessment Report, July 2011 Biomethane (Castle Eaton) Limited 12 Castle Eaton Farm AD Plant Upgrade and Extension Flood Risk Assessment 882120-R1(02)-FRA
Study Overview of key provisions and policies
Catchment Flood Management Plans (CFMP) give an overview of the flood risk from inland sources across each river catchment and recommend ways of managing those risks now and over the next 50-100 years. The EA is responsible for producing CFMPs. The site falls within the ‘Towns and villages in open floodplain (north and west)’ sub-catchment and the policy applicable to this site is Policy Option 6 which states “Areas of low to moderate flood risk where we will take action with others to store water or manage run-off in locations that provide overall flood risk reduction or environmental benefits.”. The CFMP provides the following key proposed actions: • We want to maintain the existing capacity of the river systems in developed areas that reduces the risk of flooding from more frequent events. CFMP: • We will identify locations where the storage of water could Thames benefit communities by reducing flood risk and providing Catchment Flood environmental benefits (by increasing the frequency of Management Plan flooding) and encourage flood compatible land uses and management. For example in the Roding catchment, 201114 planned flood storage will reduce the risk to local communities and larger urban areas downstream. • We will work with Local Planning Authorities to retain the remaining floodplain for uses that are compatible with flood risk management and put in place polices that lead to long-term adaptation of urban environments in flood risk areas. • We will continue to increase public awareness, including encouraging people to sign-up for the free Floodline Warnings Direct service. • We will help communities and local authorities manage local flood risk. This could include flood resilience (for example in Witney and Bampton), community flood plans that identify vulnerable people and infrastructure and community based projects (for example in East Hanney).’
3.4 Site-specific consultation
3.4.1 As part of this assessment, the following authorities have been contacted to obtain relevant data/guidance and establish key site constraints:
Table 3.4: Key site-specific consultations
Consultee Date Comments
Product data Environment September Agency 2020 Pre-application enquiry submitted, due to the site’s location in Flood Zone 1, no data has been provided.
14 Environment Agency, Great Ouse Catchment Flood Management Plan, January 2011 Biomethane (Castle Eaton) Limited 13 Castle Eaton Farm AD Plant Upgrade and Extension Flood Risk Assessment 882120-R1(02)-FRA
Consultee Date Comments
• Any proposals should be designed in accordance with the Non-statutory technical Standards for sustainable drainage systems and the latest SuDS Manual (C753) • Existing Greenfield Runoff rates for the site. • A detailed plan showing the existing drainage features on the site and how the proposed drainage strategy will be implemented; • A detailed topographical Survey that clearly identifies the existing drainage features on the site as well as level contours to show how the site falls; • Calculations to demonstrate the attenuation requirements for the 1 in 100 year plus climate change event to support the proposed strategy; • Consent for any outfalls from the proposed drainage systems into a public sewer or other drainage system not owned by the applicant. • Proposed flows from the site will discharge at or below greenfield runoff rates, or as close as practical for any areas that have been previously developed; • The impact upon the existing drainage systems is mitigated by discharging the flow throughout the management train rather than relying upon a single Local Planning point of discharge; Authority / Lead • SuDS Source Control measures to manage water Local Flood September quantity and maintain water quality have been Authority – 2020 implemented wherever possible and throughout the Swindon Borough management train so the development is not reliant Council upon large attenuation features close to the points of discharge; • Proposed SuDS have been selected to provide a wide range of benefits including amenity, biodiversity and maintaining water quality. • During construction, adequate measures are proposed to control pollution to existing watercourses and groundwater. • The strategy mimics the existing drainage characteristics of the site by retaining and utilising any existing drainage features; • If any existing drainage features such as existing watercourses (including ditches) are proposed to be removed or culverted, the applicant has agreed this with the LLFA by obtaining Land Drainage Consent or the Environment Agency (EA) for any main rivers; • Existing flood flow routes through the site (check the EA surface Water flood maps here) have been maintained or where they will be affected, adequate measures to intercept and safely control flows through the site have been provided to ensure flood risk is not increased elsewhere; • If infiltration is proposed, it is implemented in manner that does not create an offsite impact
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Consultee Date Comments
particularly if there are reports of groundwater flooding in the area, soakage tests have been carried out in accordance with DG 365 to demonstrate infiltration is feasible; • All proposed drainage features are outside flood zones 2 and 3 and where they are adjacent to an ordinary watercourse, they are not located within the EA surface water flood maps. Where drainage features are located adjacent to flood zones 2 and 3, they must be above the 1 in 100 year plus climate change flood level. This information can be provided by the EA and the applicant should have obtained this. • Details have been provided of how the proposed and existing drainage features on the site will be maintained and managed after completion with confirmation from the relevant authority that they will adopt any systems that are being offered for adoption; • The applicant should use green, shallow/above ground SuDS measures wherever feasible.
Full response included in Appendix C
3.4.2 Key findings are referred to in the relevant part of Section 4.
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4 SOURCES OF FLOOD RISK
4.1 Criteria
4.1.1 In accordance with the NPPF and advice from the Environment Agency, a prediction of the flood sources and levels is required along with the effects of climate change from the present for the design life of the development (in this case assumed to be 60 years).
4.1.2 Changes to climate change guidance in February 2016 indicate that increased allowances in peak river flow and rainfall intensity should now be incorporated within any assessment. The appropriate allowance for peak river flow is based on the site location in the country, the lifetime of development, the relevant flood zone and the vulnerability of the proposed end use.
4.1.3 The flood risk elements that need to be considered for any site are defined in BS 8533 as the “Forms of Flooding” and are listed as:
• Flooding from rivers (fluvial flood risk); • Flooding from the sea (tidal flood risk); • Flooding from the land; • Flooding from groundwater; • Flooding from sewers (sewer and drain exceedance, pumping station failure etc); and • Flooding from reservoirs, canals and other artificial structures.
4.1.4 The following section reviews each of these in respect of the subject site.
4.2 Flooding from rivers (fluvial flood risk)
Main river
4.2.1 The Environment Agency Flood Zone mapping study for England and Wales is available on their website at: https://flood-map-for-planning.service.gov.uk.
4.2.2 The latest published flood zone map (Figure 1.1), which does not take into account the effects of flood defences, shows the site to be located in Flood zone 1 (land assessed as having a less than 0.1% (1 in 1000 year) or probability of river flooding).
4.2.3 In December 2013, the Environment Agency released an additional form of mapping ‘Risk of Flooding from Rivers and Sea’, which is available at: https://flood-warning-information.service.gov.uk/long-term-flood-risk.
4.2.4 The latest ‘Risk of Flooding from Rivers and Sea’ flood map (Figure 4.1), which shows the Environment Agency’s assessment of the likelihood of flooding from rivers and the sea at any location and is based on the presence and effect of all flood defences,
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predicted flood levels, and ground levels, indicates that the site is considered to be at ‘very low’ risk of flooding.
Figure 4.1: Environment Agency ‘Flood risk from rivers or the sea’ map (accessed September 2020)
Climate change
4.2.5 Fluvial flooding is likely to increase as a result of climate change. A greater intensity and frequency of precipitation is likely to raise river levels and increase the likelihood of a river overtopping its banks; however, as the site is set above areas at risk from flooding then at present climate change is not considered to increase risk to the site.
4.3 Flooding from the sea (tidal flood risk)
4.3.1 The site is not considered to be at risk from tidal flooding due to its inland location.
Climate change
4.3.2 Climate change is not considered to result in an increased risk of tidal flooding to the site.
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4.4 Flooding from the land (overland pluvial flood risk)
4.4.1 If intense rain is unable to soak into the ground or be carried through manmade drainage systems, for a variety of reasons, it can run off over the surface causing localised floods before reaching a river or other watercourse.
4.4.2 Generally, where there is impermeable surfacing or where the ground infiltration capacity is exceeded, surface water runoff can occur. Excess surface water flows from the site are believed to drain naturally to the local water features, either by overland flow or through infiltration.
4.4.3 The Environment Agency’s surface water flood map (Figure 4.2) shows the site is predominantly at very low risk from pluvial flooding. A small number of short linear areas of surface water flood risk are mapped in the southern section of the site, which correlates with the orientation of the ploughed southern field.
4.4.4 An area of low to high surface water flood risk is mapped on the eastern boundary of the site associated with a localised topographical low adjacent to the access track. From the available plans, the rainwater and effluent lagoons are proposed in the vicinity of this location, however due to the nature these facilities, it is unlikely they will have an adverse impact on the surface water flood risk in the area.
Figure 4.2: Environment Agency ‘Flood risk from surface water’ map (accessed September 2020)
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4.4.5 The proposed development is not likely to generate additional quantities of on-site surface water runoff. This is discussed further in Section 7 and in the associated Detailed Drainage Assessment.
4.4.6 The risk of surface water flooding at the site is considered to be low.
Climate change
4.4.7 Surface water flooding is likely to increase as a result of climate change in a similar ratio to fluvial flooding. Increased intensity and frequency of precipitation is likely to lead to reduced infiltration and increased overland flow. Climate change guidance for rainfall intensity was updated by the Environment Agency in late February 2016. Revised allowances for climate change have been included in the indicative drainage strategy below.
4.5 Flooding from groundwater
4.5.1 Groundwater flooding tends to occur after much longer periods of sustained high rainfall. Higher rainfall means more water will infiltrate into the ground and cause the water table to rise above normal levels. Groundwater tends to flow from areas where the ground level is high, to areas where the ground level is low. In low-lying areas the water table is usually at shallower depths anyway, but during very wet periods, with all the additional groundwater flowing towards these areas, the water table can rise up to the surface causing groundwater flooding.
4.5.2 As noted in section 2.1.4, the BGS Borehole located 250m to the north of the site recorded groundwater at a depth of approximately 1.2m (perched above the Oxford Clay formation).
4.5.3 Within the Swindon Borough Council SFRA, notes that it is the southern areas of the borough (located above the chalk strata) where groundwater flooding is most likely to occur, with the risk of groundwater flooding in the northern areas of the borough categorised as low. The SFRA mapping however does show that the area of Castle Easton (including the northern section of the site) is shown to lie in an area where groundwater flooding could occur at the surface. The southern section of the site is not shown to lie within this area.
4.5.4 Based on the available information, the resultant Groundwater flood risk is considered to be low-medium, with any excavations or foundations to be monitored during the construction phase and dewatered if applicable.
4.5.5 Climate change
4.5.6 Climate change could increase the risk of groundwater flooding as a result of increased precipitation filtering into the groundwater body. If winter rainfall becomes more frequent and heavier, groundwater levels may increase. Higher winter recharge may however be balanced by lower recharge during the predicted hotter and drier summers. This is less likely to cause a significant change to flood risk than from other sources, since groundwater flow is not as confined. It is probable that any locally perched aquifers may
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be more affected, but these are likely to be isolated. The change in flood risk is likely to be low.
4.6 Flooding from sewers
4.6.1 Flooding from artificial drainage systems occurs when flow entering a system, such as an urban storm water drainage system, exceeds its conveyance capacity, the system becomes blocked or it cannot discharge due to a high water level in the receiving watercourse. A sewer flood is often caused by surface water drains discharging into the combined sewer systems; sewer capacity is exceeded in large rainfall events causing the backing up of floodwaters within properties or discharging through manholes.
4.6.2 Most adopted surface water drainage networks are designed to the criteria set out in Sewers for Adoption15. One of the design parameters is that sewer systems be designed such that no flooding of any part of the site occurs in a 1 in 30 year rainfall event. By definition a 1 in 100 year event would exceed the capacity of the surrounding sewer network as well as any proposed drainage.
4.6.3 When exceeded, the surcharged pipe work could lead to flooding from backed up manholes and gully connections. This could lead to immediate flooding within highways surrounding the site. As described above, surface water would most likely follow the topography of the site and flow away from the site to the south towards the watercourse.
4.6.4 The Swindon District Council SFRA does not highlight any records of sewer flooding within the area. In line with this and the agricultural setting of the site, flood risk from this source is considered low.
4.6.5 Development has the potential to cause an increase in impermeable area, an associated increase in surface water runoff rates and volumes, and a consequent potential increase in downstream flood risk due to overloading of sewers, watercourses, culverts and other drainage infrastructure.
4.6.6 To ensure that sewer and surface water flooding is not exacerbated; surface water must be considered within the design of the site. Due to the nature of the site, the surface water management is considered within the overall operations of the AD Plant.
Climate change
4.6.7 The impact of climate change is likely to be negative regarding flooding from sewers. Increased rainfall and more frequent flooding put existing sewer and drainage systems under additional pressure resulting in the potential for more frequent surcharging and potential flooding. This would increase the frequency of local sewer flooding but would not be significant in terms of the proposed development.
15 WRC, ‘Sewers for Adoption’ 8th Edition, 2020 Biomethane (Castle Eaton) Limited 20 Castle Eaton Farm AD Plant Upgrade and Extension Flood Risk Assessment 882120-R1(02)-FRA
4.7 Other sources of flooding Reservoirs
4.7.1 Flood events can occur from a sudden release of large volumes of water from reservoirs, canals and artificial structures.
4.7.2 The Environment Agency reservoir flood map (reproduced as Figure 4.4) shows the largest area that might be flooded if a reservoir were to fail and release the water it holds. Since this is a prediction of a worst-case scenario, it is unlikely that any actual flood would be this large. According to the Environment Agency Reservoir flood maps the site is not at risk of flooding from reservoirs.
Figure 4.4: Environment Agency ‘Flood risk from reservoirs’ map (accessed September 2020)
4.7.3 Reservoir flooding is also extremely unlikely. There has been no loss of life in the UK from reservoir flooding since 1925. Since then reservoir safety legislation has been introduced to ensure reservoirs are maintained.
4.7.4 The site is not shown to lie with the reservoir flood area and the resultant flood risk is considered to be very low.
4.7.5 Reservoirs can be managed over time, controlling inflow/outflow of water and therefore there is the capacity to control the effects of climate change. Increased rainfall has the
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potential to increase base flow, but this should be minimal. It is unlikely that there will be a substantial change to the risk of flooding for this site.
Canals
4.7.6 There are no Canal & River Trust owned canals within the area of the site.
Blockages of artificial drainage systems
4.7.7 There is a possibility that flooding may result due to culverts and/or sewers being blocked by debris or structural failure. This can cause water to backup and result in localised flooding, as well as placing areas with lower ground levels at risk.
4.7.8 It is noted that as part of the site operations, surface water is pumped via a series of pipes to the rainwater / effluent lagoon located in the south section of the site prior to being utilised in the fertilisation process. There is the potential that these could become blocked, however these pipes will be maintained under the everyday operations of the existing and future site. As a result, flood risk from the blockages of these systems is considered low.
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5 FLOOD MITIGATION MEASURES
5.1 Overview The site is currently proposed to be a commercial development. As a result, this end use is considered to be Less Vulnerable. The site lies wholly within Flood Zone 1. Provided that the developable area is kept located within Flood Zone 1 and outside of the risk from surface water it is not proposed that additional mitigation measures should be incorporated into the design. There are elements of best practice which should be considered at an early stage as outlined below. 5.2 Overland flood flow
5.2.1 As the Environment Agency’s online mapping suggests there is low risk from overland pluvial flow across the site (Figure 4.3), this should be factored into the design of the site. No further overland flow control measures are proposed as all surface water runoff up to the 1 in 100 year climate change storm will be stored on-site and discharged in line with Section 7 and the accompanying Detailed Drainage Assessment / Strategy. 5.3 Finished floor levels
5.3.1 As the proposed developable area will not be affected by fluvial flooding there is no need to incorporate any freeboard levels into the finished floor levels of the design. Low lying areas that could lead to ponding of surface flows will be avoided by careful design of finished levels. 5.4 Safe access/egress
5.4.1 As the proposed site access lies outside of the 1 in 1000 year climate change flood extent, safe access and egress will be available up to this storm event. For extreme events above this, it is considered appropriate that site users should be able to safely escape to an area away from the watercourse. 5.5 Environmental Permit/Ordinary watercourse easement and consents
5.5.1 Under the Water Resources Act 1991 and associated byelaws, works in, over, under or adjacent to main rivers require the consent of the Environment Agency and works in, over, under or adjacent to ordinary watercourses will require IDB, Local Authority or LLFA consent. This is to ensure that they neither interfere with the IDB/Environment Agency
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/LPA/LLFA’s work nor adversely affect the environment, fisheries, wildlife and flood defence in the locality.
5.5.2 Any consent works usually take place post planning, prior to construction; however, the principals of any development within the appropriate easements should be agreed at the planning stage. 5.6 Groundwater
5.6.1 Due to potentially high groundwater levels in the area, groundwater monitoring is recommended to be undertaken and any excavations should be monitored for groundwater ingress and dewatered if required.
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6 PLANNING CONTEXT
6.1 Application of planning policy
6.1.1 Section 14 of the NPPF includes measures specifically dealing with development planning and flood risk using a sequential characterisation of risk based on planning zones and the Environment Agency Flood Map. The main study requirement is to identify the flood zones and vulnerability classification relevant to the proposed development, based on an assessment of current and future conditions. 6.2 Land use vulnerability
6.2.1 Planning Practice Guidance (PPG) includes a list of appropriate land uses in each flood zone dependent on vulnerability to flooding. In applying the Sequential Test, reference is made to Table 6.1 below, reproduced from Table 3 of PPG.
Table 6.1: Flood risk vulnerability and flood zone ‘compatibility’
Flood Risk Essential Water Highly More Less Vulnerability Infrastructure Compatible Vulnerable Vulnerable Vulnerable Classification
Flood Zone 1 Appropriate Appropriate Appropriate Appropriate Appropriate Zone Zone 2 Appropriate Appropriate Exception Appropriate Appropriate Test Required
Zone 3a Exception Appropriate Should not Exception Appropriate Test Required be Test permitted Required
Zone 3b Exception Appropriate Should not Should not Should not functional Test Required be be be permitted floodplain permitted permitted
6.2.2 With reference to Table 2 of the PPG, the proposed development, based on its commercial / agricultural use, is classed as 'Less Vulnerable'. This classification of development is appropriate for areas within Flood Zone 1. 6.3 Sequential Test
6.3.1 The Sequential Test is required to assess flood risk and the Planning Practice Guidance recommends that the test be applied at all stages of the planning process to direct new development to areas with the lowest probability of flooding (Flood Zone 1).
6.3.2 According to the NPPF, if there is no reasonably available site in Flood Zone 1, the flood vulnerability of the proposed development (see Planning Practice Guidance Table 2) can be taken into account in locating development in Flood Zone 2 and then Flood Zone 3.
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Within each Flood Zone new development should be directed to sites at the lowest probability of flooding from all sources.
6.3.3 The development proposal is for a ‘Less Vulnerable’ commercial / agricultural use. With reference to Table 6.1 above, this development would be appropriate for areas within Flood Zone 1, subject to the implementation of an appropriate surface water drainage strategy. Therefore, the Sequential Test has been passed as the development has been situated within the lowest possible designated risk area available and therefore does not require the Exception Test to be satisfied.
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7 SURFACE WATER DRAINAGE STATEMENT
7.1 Scope
7.1.1 As development is greater than 1ha in size, the Environment Agency requires such development to focus on the management of surface water run-off. This section discusses the potential quantitative effects of the development on both the risk of surface water flooding on-site and elsewhere within the catchment, as well as the type of potential SuDS features that could be incorporated as part of the masterplan.
7.1.2 In accordance with the Defra Non-Statutory Technical Standards, the surface water drainage strategy should seek to implement a SuDS hierarchy that aspires to achieve reductions in surface water runoff rates to greenfield rates. Where a reduction to the greenfield rate is not practicable, the proposed surface water drainage strategy should not exceed the existing runoff rate.
7.1.3 In addition, Building Regulations Part H16 requires that the first choice of surface water disposal should be to discharge to an adequate soakaway or infiltration system, where practicable. If this is not reasonably practicable then discharge should be to a watercourse, the least favourable option being to a sewer (surface water before combined). Infiltration techniques should therefore be applied wherever they are appropriate. 7.2 Proposed surface water drainage strategy
7.2.1 The planning application (and this Flood Risk Assessment) will be accompanied by a Detailed Drainage Assessment / Strategy which is currently in preparation and will detail the surface water management principles of the development and its operations.
7.2.2 In principle, the strategy will likely contain the following features and criteria:
• Discharge from the AD facility will be captured within a network of perforated filter drains, leachate water drainage, process water drainage and surface formed channels as per the existing scenario; • Discharge will be pumped to a digestate lagoon within the southern section of the site and utilised within the AD process in line principles outlined in discharging Condition 10 (S/12/0317 (Discharge of Conditions S/COND/12/1476)) and the current site operations; • The digestate lagoon is proposed to be emptied during the spreading season and spread to land under the digestate management plan within the EMS governed by the EA; and
16 HM Government (2010 with 2013 amendments), ‘The Building Regulations 2010: Approved Document H - Drainage and Waste Disposal (2002 Edition incorporating 2010 amendments)’ Biomethane (Castle Eaton) Limited 27 Castle Eaton Farm AD Plant Upgrade and Extension Flood Risk Assessment 882120-R1(02)-FRA
• Engagement with a digestate contractor who has sufficient capacity to store digestate during the closed spreading season off-site should be sought if there is insufficient storage capacity in the existing lagoon. • The current drainage drawing is included in Appendix D.
7.2.3 Construction Drainage
7.2.4 Temporary drainage should be established for the construction phase of development to prevent silt mobilisation, potentially impacting on flow regimes and silt pollution downstream. These aspects will be covered by the Construction Environmental Management Plan which will be prepared and submitted with the Planning Application.
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8 CONCLUSIONS AND RECOMMENDATIONS
8.1.1 This FRA complies with the NPPF and Planning Practice Guidance and demonstrates that flood risk from all sources has been considered in the proposed development. It is also consistent with the Local Planning Authority requirements with regard to flood risk.
8.1.2 The proposed development site lies in an area designated by the Environment Agency as Flood Zone 1 and is outlined to have a chance of flooding of less than 1 in 1000 (0.1%) in any year.
8.1.3 This flood risk assessment demonstrates that the requirements of the Sequential Test have been met, with the location of the site within land assessed as being outside of the 1 in 100 year (1%) event and ‘Less Vulnerable’ classification of the development.
8.1.4 This flood risk assessment has considered multiple sources of flooding and concluded the following:
Table 8.1: Flood risk summary
Source Level of risk Overview / Mitigation
The proposed development is shown to be within Fluvial Negligible Flood Zone 1 and elevated above the closest significant watercourse.
The site is not at risk of tidal flooding due to its inland Tidal Very Low location
The site is at a low risk of surface water ponding; however, a surface water flow path extends along Surface water Low - High the existing access road, with another flow path to the west of the site of which follows the route of the existing ditch.
There are no known records of sewer flooding within this area, with the only on-site sewer being an Sewer Low abandoned foul water sewer as detailed within available sewer records.
The closest borehole to the site (250m north) indicated groundwater at approximately 1.2mbgl. in line with the Swindon SFRA, the northern section of Groundwater Low-Medium the site is in an area classed as being in an area at risk of groundwater flooding at the surface, however the southern section of the site is not included within the mapping.
Any pumped drainage network from the AD plant to Artificial sources Low the lagoon will be monitored and maintained as part of the everyday operations of the site.
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8.1.5 The proposals will follow best practice regarding site drainage to ensure that any surface water runoff from the development is managed, ensuring flood risk is not increased elsewhere. The proposed development will only result in a negligible increase to the impermeable area on-site, with the resultant runoff from the site containing pollutants. As such, it is proposed that surface water will be captured and utilised on-site within the AD process.
8.1.6 Discharge from the AD facility will be captured within a network of perforated filter drains, leachate water drainage, process water drainage and surface formed channels as per the existing scenario and discharged to the rainwater / effluent lagoons in the southern section of the site.
8.1.7 A Detailed Drainage Assessment / Strategy is in production and will accompany this Flood Risk Assessment once completed.
8.1.8 Overall, taking into account the above points, the development of the site should not be precluded on flood risk grounds.
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APPENDIX A RSK GROUP SERVICE CONSTRAINTS
1. This report and the drainage design carried out in connection with the report (together the "Services") were compiled and carried out by RSK LDE Ltd (RSK) for the client (the "client") in accordance with the terms of a contract between RSK and the "client". The Services were performed by RSK with the skill and care ordinarily exercised by a reasonable civil engineer at the time the Services were performed. Further, and in particular, the Services were performed by RSK taking into account the limits of the scope of works required by the client, the time scale involved and the resources, including financial and manpower resources, agreed between RSK and the client. 2. Other than that expressly contained in paragraph 1 above, RSK provides no other representation or warranty whether express or implied, in relation to the Services. 3. Unless otherwise agreed in writing, the Services were performed by RSK exclusively for the purposes of the client. RSK is not aware of any interest of or reliance by any party other than the client in or on the Services. Unless expressly provided in writing, RSK does not authorise, consent or condone any party other than the client relying upon the Services. Should this report or any part of this report, or otherwise details of the Services or any part of the Services be made known to any such party, and such party relies thereon that party does so wholly at its own and sole risk and RSK disclaims any liability to such parties. Any such party would be well advised to seek independent advice from a competent environmental consultant and/or lawyer. 4. It is RSK’s understanding that this report is to be used for the purpose described in the introduction to the report. That purpose was a significant factor in determining the scope and level of the Services. Should the purpose for which the report is used, or the proposed use of the site change, this report may no longer be valid and any further use of or reliance upon the report in those circumstances by the client without RSK's review and advice shall be at the client's sole and own risk. Should RSK be requested to review the report after the date of this report, RSK shall be entitled to additional payment at the then existing rates or such other terms as agreed between RSK and the client. 5. The passage of time may result in changes in site conditions, regulatory or other legal provisions, technology or economic conditions which could render the report inaccurate or unreliable. The information and conclusions contained in this report should not be relied upon in the future without the written advice of RSK. In the absence of such written advice of RSK, reliance on the report in the future shall be at the client's own and sole risk. Should RSK be requested to review the report in the future, RSK shall be entitled to additional payment at the then existing rate or such other terms as may be agreed between RSK and the client. 6. The observations and conclusions described in this report are based solely upon the Services, which were provided pursuant to the agreement between the client and RSK. RSK has not performed any observations, investigations, studies or testing not specifically set out or required by the contract between the client and RSK. RSK is not liable for the existence of any condition, the discovery of which would require performance of services not otherwise contained in the Services. For the avoidance of doubt, unless otherwise expressly referred to in the introduction to this report, RSK did not seek to evaluate the presence on or off the site of asbestos, electromagnetic fields, lead paint, heavy metals, radon gas or other radioactive or hazardous materials. 7. The Services are based upon RSK's observations of existing physical conditions at the site gained from a walk-over survey of the site together with RSK's interpretation of information including documentation, obtained from third parties and from the client on the history and usage of the site. The Services are also based on information and/or analysis provided by independent testing and information services or laboratories upon which RSK was reasonably entitled to rely. The Services clearly are limited by the accuracy of the information, including documentation, reviewed by RSK and the observations possible at the time of the walk- over survey. Further RSK was not authorised and did not attempt to independently verify the accuracy or completeness of information, documentation or materials received from the client or third parties, including laboratories and information services, during the performance of the Services. RSK is not liable for any inaccurate information or conclusions, the discovery of which inaccuracies required the doing of any act including the gathering of any information which was not reasonably available to RSK and including the doing of any independent investigation of the information provided to RSK save as otherwise provided in the terms of the contract between the client and RSK. 8. The phase II or intrusive environmental site investigation aspects of the Services is a limited sampling of the site at pre- determined borehole and soil vapour locations based on the operational configuration of the site. The conclusions given in this report are based on information gathered at the specific test locations and can only be extrapolated to an undefined limited area around those locations. The extent of the limited area depends on the soil and groundwater conditions, together with the position of any current structures and underground facilities and natural and other activities on site. In addition, chemical analysis was carried out for a limited number of parameters [as stipulated in the contract between the client and RSK] [based on an understanding of the available operational and historical information,] and it should not be inferred that other chemical species are not present. 9. Any site drawing(s) provided in this report is (are) not meant to be an accurate base plan but is (are) used to present the general relative locations of features on, and surrounding, the site. Features (boreholes, trial pits etc) annotated on site plans are not drawn to scale but are centred over the appropriate location. Such features should not be used for setting out and should be considered indicative only.
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APPENDIX B DEVELOPMENT PROPOSALS
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APPENDIX C SWINDON LLFA CORRESPONDENCE
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APPENDIX D CURRENT DRAINAGE ARRANGEMENT
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