Didcot a Prior Approval

DIDCOT A POWER STATION DEMOLITION

Prior Approval: Feb 2014 Supporting Information

Copyright © 2009 RWE npower Liability All pre-existing rights reserved. In preparation of this document RWE npower has made reasonable efforts to ensure that the This document is supplied on and subject to content is accurate, up to date and complete the terms and conditions of the Contractual for the purpose for which it was contracted. Agreement relating to this work, under which RWE npower makes no warranty as to the this document has been supplied, in particular: accuracy or completeness of material supplied by the client or their agent. Confidentiality This document is confidential. Other than any liability on RWE npower detailed in the contracts between the parties for this work RWE npower shall have no liability for any loss, damage, injury, claim, expense, cost or other consequence arising as a result of use or reliance upon any information contained in or omitted from this document.

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Didcot A Power Station Demolition Prior Approval: Supporting Information

Contents

PART A: Prior Approval

1 Introduction ...... 5 2 Purpose of this Document ...... 5 3 Prior Approval ...... 6 3.1 Legal Framework ...... 6 3.2 Prior Approval Process (and ongoing communication) ...... 7

PART B: Site and Site Works

4 Site Description ...... 9 5 Project Description ...... 9 5.1 Demolition Overview ...... 12 5.1.1 Asbestos Survey ...... 12 5.1.2 Drainage ...... 12 5.1.3 Site Set-up ...... 12 5.1.4 Temporary Fencing ...... 12 5.1.5 Site Compound ...... 12 5.1.6 Welfare and Site Offices...... 12 5.1.7 Delivery of Plant and Materials ...... 12 5.1.8 Permit to Work ...... 13 5.1.9 Plant Exclusion and Drop Zone ...... 13 5.1.10 Removal of Top Soil...... 13 5.1.11 Pre-soft Strip ...... 13 5.1.12 Asbestos Removal ...... 13 5.1.13 Soft Strip ...... 14 5.1.14 Scaffold/temporary supports ...... 14 5.1.15 Demolition – general ...... 15

5.1.16 Hand Demolition ...... 15 5.1.17 Mechanical Demolition ...... 15 5.1.18 High Reach Demolition...... 15 5.1.19 Processing Material ...... 16 5.1.20 Removal of Arisings ...... 17 5.1.21 Crushing ...... 17 5.1.22 Explosive Demolition: Blast Design ...... 17 5.1.23 Vibration air over pressure ...... 17 5.1.24 Pre weakening and drilling ...... 17 5.1.25 Temporary works ...... 17 5.1.26 Blast protection ...... 18 5.1.27 Test blast ...... 18 5.1.28 Security of site when charging building ...... 18 5.1.29 Main blast ...... 18 5.1.30 Blow-down day ...... 18 5.1.31 Safety Check following blow-down ...... 18 5.1.32 Civilise the Debris Pile ...... 19 5.1.33 Street Cleaning within Site ...... 19 5.1.34 Lifting of the Exclusion Zone ...... 19 6 Environmental Factors ...... 19 6.1 Traffic and Transport ...... 19 6.1.1 Introduction ...... 19 6.1.2 Heavy Goods Vehicles ...... 20 6.1.3 Vehicle Movements ...... 22 6.1.4 Abnormal Loads ...... 22 6.1.5 Personnel on Site ...... 23 6.1.6 Mitigating Proposals ...... 24 6.1.7 Previous Traffic Impact ...... 24 6.1.8 Potential Traffic impact – demolition ...... 25 6.1.9 Site Management ...... 26 6.2 Noise, Vibration, and Dust ...... 29 6.2.1 Baseline Noise Data ...... 29 6.2.2 Predicted Noise ...... 29 6.2.3 Summary of predicted noise impacts ...... 33

6.2.4 Noise Control Measures ...... 36 6.2.5 Ongoing Monitoring ...... 37 6.2.6 Vibration impacts ...... 38 6.2.7 Ground vibration ...... 39 6.2.8 Predicted Ground Vibration Levels ...... 39 6.2.9 Air over pressure ...... 41 6.2.10 Predicted Levels: Air over pressure ...... 42 6.2.11 Discussion of Vibration Predictions ...... 43 6.2.12 Control Measures (vibration and air over pressure)...... 43 6.2.13 Dust ...... 44 6.2.14 Dust Control Measures ...... 44 6.2.15 Dust monitoring ...... 46 6.3 Land Contamination ...... 46 6.3.1 Site history ...... 47 6.3.2 Site geology ...... 49 6.3.3 Storage and control of potentially polluting materials on site during operation ...... 50 6.3.4 Potentially polluting materials on site ...... 50 6.3.5 Ground contamination studies ...... 51 6.3.6 Environmental Permit application ...... 52 6.3.7 Decommissioning process for potentially contaminating materials ...... 52 6.3.8 Control Measures during Demolition ...... 53 6.4 Ecology ...... 56 6.4.1 Baseline Ecology ...... 56 6.4.2 Predicted Impacts and Mitigation ...... 62 7 Programme of Works ...... 66

FIGURES

1. Site Context 2. Demolition Boundary 3. Demolition Zones 4. Low Loader (21m) 5. Bulker Lorry (13m) 6. 8m wheeled vehicle 7. Parking area for personnel vehicles 8. Site access and on-Site transport routes 9. Control measures for transit routes below live cables

10. Example of rigid goal posts and barriers for sites where plant pass under a line 11. Noise Monitoring Locations 12. Noise Receptor Locations 13. Predicted Noise Levels at Receptor 1 and associated duration 14. Predicted Noise Levels at Receptor 2 and associated duration 15. Predicted Noise Levels at Receptor 3 and associated duration 16. Predicted Noise Levels at Receptor 4 and associated duration 17. Predicted Noise Levels at Receptor 5 and associated duration 18. Predicted Noise Levels at Receptor 6 and associated duration 19. Predicted Noise Levels at Receptor 7 and associated duration

APPENDICES

1. General Demolition Method Statement 2. General Site Logistics and traffic 3. Cooling Tower Explosive Demolition Method Statement 4. Chimney Stack Explosive Demolition Method Statement 5. Precipitators and Ducts Demolition Method Statement 6. Boiler House, Tank and Bunker Bay Demolition Method Statement 7. Turbine Hall De-planting and Demolition Method Statement 8. Auxiliary Buildings (Steel and Concrete framed) Demolition Method Statement 9. Auxiliary Buildings (Petrochemical and WTP) Demolition Method Statement 10. Explosive Demolition Management 11. Scrap Yard Method Statement 12. Screening Opinion 13. Traffic Management Plan 14. Noise Predictions - worked example 15. Vibrock Report: Feasibility of Explosive Demolition 16. Environmental Management Plan 17. Ecological Assessment 18. Programme

PART A: Prior Approval

1 Introduction 1. Didcot A is a coal fired power station which was previously capable of generating 2000MW of electricity. The power station was constructed during the 1960’s and commenced operation in 1970. It was originally constructed as a coal fired power station but also had the ability to burn natural gas and biomass. The Large Combustion Plant Directive (LCPD) of 2001 requires large combustion plants such as power stations to meet specific environmental standards by the end of 2015 and those that cannot meet these standards are required to close. Due to the age of the power station it was not considered economic to refit the plant in accordance with the requirements of the LCPD and therefore the station was required to close on completion of 20,000 hours of operation (from 1st January 2008), or by the end of 2015 at the latest. 2. The Didcot A power station site is approximately 204 acres in size. The site is generally open with grassed areas and hard standing separating many of the previously operational buildings. Various pipelines, cable routes and water ways cross the site under, on or above the ground. The power station was direct cooled and abstracted and discharged water to/from the River Thames. 3. Didcot A Power Station officially closed in March 2013 and then entered a period of decommissioning. Following the decommissioning the station and all ancillary structures will be demolished to ground level. It is estimated that approximately 114 acres of land will be declared surplus to operational requirement and released for development. The remaining land (90 acres) will be retained for possible future development of power generation. 4. The vast majority of Didcot A Power Station is located within the Vale of White Horse District, however, the site boundary for Didcot A Power Station abuts South Oxfordshire’s District boundary and the site access road falls within South Oxfordshire. 5. Although Didcot A power station is no longer generating, the site is still regulated by an Environmental Permit as issued by the Environment Agency.

2 Purpose of this Document 6. This document sets out to fulfil the requirements of the prior approval process by detailing the demolition methodologies and discussing the potential environmental consequences along with the need for control measures and appropriate monitoring where applicable. The subject areas highlighted within the Screening Opinion (referred to in paragraph 13) are: • Transport • Noise, Vibration , Air Quality (Dust)

• Land Contamination • Ecology 7. The potential impacts relating to each of these topics are covered and discussed in this report, along with associated control measures. Further detail regarding the demolition method statements are provided in Appendix 1-11.

3 Prior Approval 3.1 Legal Framework 8. Following a court of appeal judgement in March 2011 the types of demolition that need 'prior notification' has been broadened to include all demolition where planning consent has not already been granted for the redevelopment of a site. Development has always included 'demolition' within its definition and as such been subject to control under the Planning Act. 9. This judgement has quashed paragraphs 2(1)(a) to (d) of the Town & Country Planning (Demolition - description of buildings) Direction 1995 (contained in DOE circular 10/95). 10. As a result, demolition of the following is now classed as 'development' and brings them into line with the treatment of residential buildings: • demolition of a listed building • a building in a conservation area • building which is a scheduled monument • a building that is not a dwelling house • a building adjoining a dwelling house

11. Permitted development rights for the above forms of development now apply under Part 31 of the Town and Country Planning (General Permitted Development) Order 1995. As such, if the proposed development is not being undertaken in conjunction with a planning application for the redevelopment of a site, a prior notification application is required to be submitted to the Local Planning Authority to check whether the Council requires prior approval of the method of demolition. 12. In addition the court of appeal has also concluded that demolition works fall within the scope of the Environmental Impact Assessment (EIA) directive. The effect is that where demolition works are likely to have significant effects on the environment, the Local Planning Authority (LPA) must issue a screening opinion on whether an environmental impact assessment is required. 13. RWE npower received a Screening Opinion from the Vale of White Horse District Council in February 2012 confirming that the submission of an Environmental Statement in connection with the proposed demolition works was not required. The screening opinion assessment report concluded the following: 14. “In assessing the potential impacts of the proposed development, the relevant environmental impacts have been considered. Whilst these impacts may have some local significance, they can be suitably assessed and mitigated as part of the prior

approval process which has been adjudged as being able to provide the necessary level of control required based on legal advice and guidance. 15. Consideration has also been given to the regulatory powers of other bodies to avoid any duplication of control and resources in the control of the demolition process and the impact that this would have on the local and wider environment. 16. The Council is therefore satisfied that the prior approval process outlined under Part 31 of the Town and Country Planning (General Permitted Development) Order 1995 (as amended) will provide sufficient control to manage and mitigate the environmental impacts during the demolition works. 17. Overall it is considered that the proposal is not development that would generate the need for an EIA and taking into account other means of control by the council and other regulatory bodies it is considered therefore, an Environmental Statement is not required.” 18. The full Screening Opinion and supporting assessment report can be found at Appendix 12.

3.2 Prior Approval Process (and ongoing communication) 19. The following steps have been (or will be) followed as part of the prior approval process: • Screening Opinion - received from the Vale of White Horse District Council in February 2012 confirming that the submission of an Environmental Statement in connection with the proposed demolition works was not required. • Engagement of stakeholders – continued open dialogue with the Local Planning Authority in the run up to closure and throughout decommissioning. Meetings held, and site visits conducted with Planning officers and Environmental Protection officers. Regular updates/meetings to continue throughout the demolition process. • Community Liaison – Drop in sessions were held on 20/21st February 2013 and 24/25th September 2013 to inform local residents of the closure of the power station and the planned demolition activities. The sessions were advertised in the local press, via letter drop, and local radio. • A Prior Notification application was made on 23rd October 2013 for the demolition of the coal conveyors and associated structures (Reference P13/V2328/D). Approval was granted on 20th November 2013. • A letter to local residents was issued on 9th December 2013 notifying of the proposed start date for the coal conveyors. • Application to LPA - apply to the local planning authority for a determination as to whether the prior approval of the authority will be required to the method of demolition (as outlined under Part 31 of the

Town and Country Planning (General Permitted Development) Order 1995 (as amended)). • Provision of supporting information to the LPA - This document (Prior Approval: Supporting Information, February 2013) is submitted with the application for prior notification as supporting information detailing the demolition methodologies and environmental controls to be employed during the demolition process. • Certification / approval by the relevant authorities. • Provision of additional information to Vale of White Horse as required. • Ongoing communications: Notice boards will be erected to the external perimeter boundary displaying the Head Office telephone number for the demolition contractor and social media contact details. RWE will issue press office contact details with local paper publications and the demolition contractor will periodically issue contact details with local paper publications. • In the event of any concerns arising, members of the public will be able to contact the demolition contractor’s Head Office and speak with the demolition contractor. The concerns will be investigated and the member of the public will then be informed by the demolition contractor of the initial findings, which will also be provided to RWE. If further information is required or if the member of the public is not satisfied with the way the concern is being handled this would be escalated to the RWE Project Manager.

20. Part B of this supporting document, along with the attached appendices, details the planned methods of demolition along with the control measures which will be implemented to ensure that any associated environmental impact is minimised.

PART B: Site and Site Works

4 Site Description 21. The site of the Didcot A power station (the “Site”) is located at Didcot in Oxfordshire (OX11 7HA), National Grid Reference SU 512917 (coordinates of the central stack). The Site lies mainly within the Vale of White Horse District Council within the County of Oxfordshire. A small area in the south east corner of the Site lies within South Oxfordshire District Council (Figure 1).The Site is wholly owned by RWE npower and covers approximately 204 acres. 22. The Site is located to the north west of the town of Didcot. The immediate surrounds comprise Didcot B power station to the west, the National Grid substation to the north, a light industrial park and sewage treatment works to the east and the Great Western railway line and B4130 to the south. Prior to the construction of Didcot A power station, the Site was a Central Ordnance Depot which was originally constructed on agricultural land with open fields. 23. The nearest residential properties lie approximately 400m to the south east of the Site. A large high bay warehouse unit and landscape buffer lie between the Site and these residential properties. In addition to the main generating plant, the Site also contains a coal stockyard and rail facility where coal was delivered by rail and stored.

5 Project Description 24. The Project is for the demolition of the former Didcot A Power Station. Buildings and structures to be demolished are listed below, and shown on Figure 2. Although included here for completeness, the coal conveyor, surge tower and reclaim hopper are covered by the prior notification application (P13/V2328/D) referred to in section 3.2 • Control Room (2) • Turbine House (Steam Turbines 1-4) and all ducts, ductwork and associated fans and equipment (3) • Boiler House (Boilers 1-4) and all ducts, ductwork, and associated fans and equipment (4) • Purge Coolers (5) • Precipitators (6) • CW Pump House (7) • Weighbridges (10) • Water Treatment Plant (11) • Coal Plant Control and Amenities Block (13) • Admin Offices (15)

• Welfare Block (16) • Store Building (18) • Station Restaurant (19) • Heavy Plant Garage (21) • Contractors Compound (22) • Stack (Grid Ref 451267, 191750) (23) • Cooling Towers (24) • Existing Biomass (25) • Biomass Store (26) • Workshop and Store (27) • Visitor Centre (28) • Ash Pits (30) • Outdoor Materials Store (31) • Conveyor (32) • Dosing Tanks and Plant House (34) • Boiler Lighting up House (36) • Lighting up Oil Tank (37, 38) • Dust Compressor House East (39) • Dust Compressor House West (39a) • Dust Bunker (40) • Switch and Compressor House (40a) • Hydrogen Store (42) • Chlorination Plant (43) • Garages, Drum Storage, Paint Store (44) • Coal Unloading House (46) • Surge Tower (47) • Reclaim Hopper (48) • Transfer Tower (49) • Tower 1 Substation (50) • Coal Store Effluent Treatment Plant (51) • Milton Road Foul Pump House (52) • Domestic Boiler and Oil Tanks (54) • Dirty Water Collection Tank (55) • Propane Tanks (56) • Heavy Oil Fuel Storage (57) • Pipe Culvert (59) • LP Pump House (60) • HP Pump House (61) • Coal Ash and Oil Services Sub Station (62)

25. It should be noted that the gas fired Didcot B power station lies immediately adjacent to the Site and this power station will remain operational. In addition, in the area of land between Didcot A and B power stations there are located four open cycle gas turbines and a stack (approximately 99m high). These structures lie outside the demolition boundary. The OCGT stack and turbines will remain. An area immediately to the north of the demolition boundary is leased to National Grid and contains a 400kv sub station. This substation will also remain. 26. The Site consists of numerous buildings of varying structure type and height. For the purposes of the demolition and to ensure a simplified approach to the overall site logistics the Site has been zoned into 7 distinct working areas (Figure 3). The building within each zone are listed below, note that zone 7 contains structures which have been demolished during the Early Works, as detailed in the previous Prior Approval Notification. • Zone 1: Southern Cooling Towers • Zone 2: Northern Cooling Towers • Zone 3: Control room (2) Turbine House, tank bay, coal hoppers (3), Boilers House (4) precipitators and ducts (6), lighting up oil tank (38), low level surrounding buildings • Zone 4: Water treatment plant (11), RFW tanks (12), Admin offices (15), Welfare block (16) Building 18 – Store Building (18), Station Restaurant (19), Workshop & Store (27), Lighting Up Oil Tank (38), Garage, Drums and Paint Store (44), Dirty Water Collection Tank (55), Other low level surrounding buildings • Zone 5: Building 13 – Coal Plant Control & Amenities Block (13), Heavy Plant Garage (21), Existing Biomass Store (25), Ash Pits (30), Outdoor material Store (31), Conveyor (32), Transfer Tower (49), Tower 1 Sub- station (50), Pipe Bridge (59), Other low level surrounding buildings • Zone 6: Lighting up oil tank (37), Lighting up oil tank (38), Dust bunker (40), Propane tanks (56), Heavy fuel storage (57), other low level surrounding buildings. • Zone 7: Coal store (13), Conveyor (32), Coal unloading house (46), Surge tower (47), Reclaim hopper (48).

27. Method statements for the demolition activities are provided in Appendix 1-11. Details of any control measures required to ensure that potential environmental impacts associated with the demolition are managed appropriately are provided in Sections 6 of this report. All work will be carried out in accordance with relevant Health Safety and Environmental regulations and standards including the Construction & Design Management (CDM) regulations.

5.1 Demolition Overview 28. A description of the proposed works is provided in the Demolition Method Statements (DMS) (Appendix 1-11). A summary of the generic demolition methods is provided below.

5.1.1 Asbestos Survey 29. Asbestos surveys have been conducted by suitably accredited bodies. The locations, extent and types of presumed or known Asbestos Containing Materials (ACM) have been identified and recorded prior to any intrusive works. Samples have been collected to determine the type and condition of asbestos present. The survey has been carried out by suitably qualified personnel and conducted in accordance with recommended guidance HSG264:2012.

5.1.2 Drainage 30. All drainage within and around the demolition site will be investigated prior to demolition and any live drainage will be afforded adequate protection prior to demolition works commencing. Live drainage will be maintained during the period of the demolition works. Any surface water drainage exiting the Site will continue to be managed and released in line with the Site Environmental Permit.

5.1.3 Site Set-up 31. A preliminary inspection of the Site will be undertaken. The Site will be fully secured at all times to prevent unauthorised access. Zone separations will be installed to facilitate the controlled process of the demolition works. Site access/egress will be prepared as well as lay-down areas for satellite welfare within each zone.

5.1.4 Temporary Fencing 32. The fencing to be used may include Heras fencing, wooden hoarding, chain-link fencing, metal palisade fencing and close board fencing. The most suitable option will be chosen depending on its purpose and the nature of the area being fenced. Where required the line of the fence/hoarding will be checked prior to installation, and a Cable Avoidance Tool (CAT) scan carried out prior to any excavation.

5.1.5 Site Compound 33. The site compound will be an area designated for welfare/plant/gas oil/tool store, located on existing temporary hard standing where appropriate.

5.1.6 Welfare and Site Offices 34. For satellite welfare and offices steel container units will be delivered and sited by HI-AB Lorry or delivered by low loader and lifted off by 360°excavator with tested and certified link and chains.

5.1.7 Delivery of Plant and Materials 35. The delivery of plant and materials will be co-ordinated by the demolition contractor’s Site Supervisor and the time of delivery will be timed so as not to

unduly inconvenience local residents. Where local residents may be affected, adequate liaison will take place.

5.1.8 Permit to Work 36. Permits to work are located within the Site Starter Pack (a set of forms and site induction information) which is provided by the demolition contractor. All Permits must be completed prior to and signed off following all permitted works by the Site Supervisor. These include the initial Permit to Work, Hot Work Permit, Permit to Remove Asbestos, Permit to Lift, Permit to Dig. Prior to any permit being issued checks will be undertaken to ensure that the works can be undertaken safely.

5.1.9 Plant Exclusion and Drop Zone 37. A suitable and site specific Traffic Management Plan shall be implemented on site to segregate pedestrians and site traffic. When in operation all plant and machinery regardless of size, will work in isolation from other works. Drop zone areas will be set up as and when required.

5.1.10 Removal of Top Soil 38. The machinery used for the removal of topsoil will include a 360°excavator, dozer, loading shovel (wheeled or tracked), and/or skidsteer with bucket attachment. Any topsoil required to be stripped during the works will be stockpiled on site, to be reused on site for bunding or site cover.

5.1.11 Pre-soft Strip 39. In order to minimise the amount of material sent to landfill any recyclable materials remaining within the site structures will be removed prior to demolition where possible. All asbestos containing materials (ACM) will be clearly identified as per the HSG264:2010 refurbishment /demolition survey. Precautions will be taken to eliminate the potential for the disturbance of ACM prior to the removal by a licensed contractor.

5.1.12 Asbestos Removal 40. Air Quality surveys will be carried out before, during, and after the removal of asbestos materials to monitor the presence or otherwise of asbestos in the areas where removal takes place. 41. The demolition contractor will assess whether the asbestos containing materials (ACM) are notifiable as licensed materials or Notifiable non-licensed under Control of Asbestos Regulations 2012 (CAR 2012). Prior to the removal of Notifiable Asbestos a Fourteen-Day Notice to the HSE (form ASB5) will be in place, and an ASBNNLW1 will be issued to the HSE for non-licenced notifiable asbestos removal. 42. A licensed sub-contractor will remove Notifiable Asbestos in accordance with the CAR 2012. Generally Non Notifiable Asbestos will be removed by competent individuals and methods used will be in line with the HSE ‘asbestos essentials’. All Notifiable non-licensed ACM will be notified to the HSE prior to works commencing.

43. All ACM’s (Notifiable licensed asbestos; Notifiable non-licensed; and non-notifiable asbestos) will be removed by suitably trained personnel equipped with the required Personal Protection Equipment (PPE) and Respiratory Protection Equipment (RPE) – Disposal overalls / Half face masks and P3 Filters which will be face fitted by a competent person to the specified model. 44. All Non-Notifiable Asbestos will be removed whole where possible. Typical methods include operatives using hand held scrapers e.g. for remove of floor tiles. The material will be kept damp using a fine water spray. Hepa vacuums will be used to control dust and fibre release. All areas which are notifiable asbestos will be deemed ‘designated areas’ with safety notices in place and access restricted. Work with licenced notifiable asbestos will typically use enclosures as per the Plan of Work. Medical surveillance and health records will be maintained for ALL notifiable asbestos work. 45. All Notifiable Asbestos will be stripped and removed as per the approved licensed contractor’s Plan of Work which will have been notified with the ASB5 to the HSE and the approved method statement and risk assessment. Any asbestos will be placed in red asbestos bags, tied securely and placed into a clear asbestos bag and tied securely. The bagged asbestos will loaded by hand into a sealed lockable container. The container once full will be removed from site in accordance with Duty of Care Regulations. 46. ACMs will be removed from the building at regular intervals ensuring that hazardous substances are not accumulating on site causing risk to operatives or trespassers. Non-Notifiable Asbestos will be removed, as far as possible, in isolation to other activities on site. There may be a potential to use the same transit route on site, depending upon the site layout. Where this is not possible, static air sampling will be undertaken prior to the route being cleared for use by others.

5.1.13 Soft Strip 47. Recyclable material within each of the structures will be identified, (i.e. wood, plastic, glass, copper, metals, bricks, blocks and tiles) in order into minimise the amount of materials being disposed of at landfill sites. 48. Using hand held tools, operatives will remove all deleterious material back to the bare structural fabric of the building. Materials will be separated where possible for recycling. The soft strip will take place in all rooms and communal areas and out buildings, all soft strip arisings will be removed from site. Properties that require roof removal by hand will be accessed by scaffold previously erected by a competent scaffolding contractor. Operatives wearing fall arrest equipment and attached to proprietary safety lines will systematically strip roof tiles, lath and felt, purlins, trusses and joists. All material will be separated at source for recycling and disposal.

5.1.14 Scaffold/temporary supports 49. All Scaffolding will be erected in accordance with BS EN12811 and the NASC's TG20; SG4. Scaffolding will be erected by scaffolders certified under the Construction Industry Scaffolders Record Scheme.

5.1.15 Demolition – general 50. All Demolition will be undertaken in a safe and controlled manner in accordance with BS 6187: 2011 Code of Practice for Demolition, Health & Safety Guidance Notes. • All material where viable will be recycled; • All Health & Safety Legislation will be complied with; • All access and egress routes will be kept clear at all times; • All leading edges will be afforded sufficient protection; • Traffic Management Plans will be adhered to and Pedestrians will be segregated from all works; • All Plant and Machinery to work in isolation of other works (Heras Fencing)

51. Generally demolition will be carried out taking full account of the structural make- up of the buildings/structures. For traditional demolition, the works will be carried out starting at the top of the structure, working within structural bays, bay by bay. No structures will be left in an unstable state overnight.

5.1.16 Hand Demolition 52. Operatives using Hand Held Mechanical Tools will ensure all tools are correct for the job. All Compressed Air Hoses will have Anti Whip Line Attachments fitted. Generally walls requiring hand demolition will be topped in working left to right top to bottom unless otherwise specified.

5.1.17 Mechanical Demolition 53. A 360o Excavator of adequate reach for the work will be used for roof removal. The type of Demolition Attachment will be dependent on the structural material of the roof- 1. Rotating Grapple for Timber Structure; 2. Concrete Demolition Attachment for Concrete Slab Roof; 3. Bucket Attachment for Bison Beam / Wood Wool Type Roof; 4. Shear Attachment for Steel Structures. 54. Generally roofs will be removed systematically in bays and all roof structure materials will be processed and separated at source for the purpose of recycling. Recyclable materials will be carefully separated at each stage of the demolition process.

5.1.18 High Reach Demolition 55. Ultra High Reach (UHR) and High Reach (HR) machines will be used for the demolition of tall structures where explosives are not used. 56. The risks and control measures associated with this method are: 57. Safe exclusion zone:

58. The structure will be demolished within a safe working area. The site boundaries will be established to create a secure perimeter, within which internal exclusion zones will be erected using Heras fencing. 59. The safe working area will be confirmed once the space available for both the high reach machine and also the falling debris has been checked and identified. 60. To ensure that demolition debris is contained the area in front of the high reach machine a void will be excavated to form a containment area. 61. Progressive collapse: 62. Structural demolition will be designed and assessed to ensure that all structural requirements are met in order to undertake safe deconstruction / demolition. The findings of the assessment will be used to ensure that the demolition sequence for removing the structural elements is correct. It will also be used to ensure that the structure will remain stable at all stages of the demolition. 63. The machine and its equipment will be erected on a prepared area of level ground. The high reach arm will be fitted and commissioned by qualified plant engineers. The machine operator will be in attendance at all times. 64. When the high reach machine has been completely assembled it will be tested by the plant engineer and certified fit for use. The working position will be as the project drawing. The plant will be under the control of the site manager and the guidance of a competent banksman who will be in radio contact with the operator. 65. Working methods: 66. The machine will be equipped with a hydraulic concrete cracker, which will pulverise the structure. Generally the block will be progressively reduced in height within structural bays. The block will be reduced in a top down manner working progressively across the building, bay by bay left to right removing a structural bay at a time within the structural walls of the building. 67. The arisings will be removed from the lower floors and allowed to drop in a controlled manner into the area of safety between the block and the machine. A separate 360°excavator on conventional demolition configuration will, using a concrete cracker, demolish the lower levels less than four storeys in height. 68. During this low level demolition a dedicated person will suppress dust emissions by means of a fire hose fed from a metered standpipe. All buildings will be demolished during the working day and made safe in that same day ensuring that the structure is left in a safe manner overnight. 69. Upon completion of the High Reach demolition, the UHR Machine will be de-rigged removed from site and replaced by a suitable sized 360°excavator, which will be used for the continuation of the works.

5.1.19 Processing Material 70. All concrete will be pulverised to a suitable size to allow loading onto lorries and suitable for further processing at a mobile crushing plant. Processed material will be stockpiled for future use on site in areas agreed with RWE.

5.1.20 Removal of Arisings 71. Load Log tickets for all arisings removed from site shall be recorded and input onto a database to produce quarterly Recycling KPIs.

5.1.21 Crushing 72. The Local Authority’s Environmental Health Department and the Environment Agency will be notified of the installation of Mobile Crushing Plant to ensure compliance with the Environmental Protection Act 1990. 73. Care will be taken to locate the plant on site to minimise the potential for impact on the environment. Where required, dust suppression will be supplied to the Crushing Plant.

5.1.22 Explosive Demolition: Blast Design 74. All works will be carried out in accordance with BS 5607 and a suitably qualified Explosives Engineer will be appointed. The Explosives Engineer will consult the structural drawings and propose a collapse mechanism, including areas of the number of blast floors, pre weakening, drilling, weight of charges, initiation sequence and primary (at source), secondary blast protection and any properties that may require protection

5.1.23 Vibration air over pressure 75. An independent Consultant who specialise in the assessment and recording of noise, vibration and Air over Pressure levels during a blow-down will be appointed. On the day of the Explosive Demolition (blow-down) the Consultant will place a number of seismographs around the area previously specified by the Consultant. The seismographs will record the vibration levels during the blow-down.

5.1.24 Pre weakening and drilling 76. Drawings and calculations indicating which structural elements (walls) of the building are to be removed will be provided by the Structural Engineer to enable the controlled explosive collapse of the building. The Explosives Engineer will mark out the walls with spray paint showing the extent of area of to be removed 77. All debris will be cleared on a regular basis to prevent overloading of the floor slabs. All re-bar will be cut back flush to the concrete. 78. Holes that require drilling will be marked out by the Explosives Engineer. To reduce Hand Arm Vibration Syndrome a 360°Excavator equipped with a drilling rig will be used where possible.

5.1.25 Temporary works 79. Various methods of protection may be required to facilitate the protection of structures, or services that could be in the immediate vicinity of the blow-down. These include: • Bunding to prevent debris splash • Anti-vibration trenches for protection to services

5.1.26 Blast protection 80. Blast protection will be subject to the findings of the test blast and may consist of Geotextile sheeting, Chain link fencing, Polypropylene rope and Hilti fixings. At source blast protection will be fixed to all sections of the structure that are displaced with explosive charges. Secondary blast protection (External) will be fixed to the external face of the structure to all blast levels 81. Chain link will be wrapped around the section of wall and secured by chain link tying wire. Ground floor level will have chain link fencing secured to the total perimeter of the structure. Geotextile sheeting will then be wrapped around the chain link fencing. All previously drilled holes will be clearly marked or exposed to facilitate the insertion of explosive charges

5.1.27 Test blast 82. A test blast will be undertaken to ascertain the sufficiency of the explosive charges and blast protection. This will be undertaken a minimum of 4 weeks prior to charging. Witness boards will be erected around the test blast section of structure, the boards will be painted white thus aiding the identification of projectiles which may result from the failure of at source protection.

5.1.28 Security of site when charging building 83. All explosives brought to site will be to fulfil the charging programme; at no time will insecure explosives be left on site overnight. 24 hour security will be in place from commencement of charging to the day of the blow-down. The Police will be notified of all activities involving the delivery and storage of all explosive equipment.

5.1.29 Main blast 84. The Explosives Engineer will insert the explosive charges in the previously drilled holes. All personnel will be evacuated from the building prior to the Explosive Engineer running out the firing line to the previously designated firing point. All non- essential personnel will be evacuated from the zone.

5.1.30 Blow-down day 85. The Consulting Engineer, Explosives Engineer and the Contract Manager will jointly agree a suitable and safe temporary exclusion zone prior to the day of the blow- down. This will be established by means of existing boundary fencing, Heras Fence panels, pedestrian barriers and fixed structures. All protection and temporary works will be carried out prior to blow-down. All unauthorised personnel will be instructed to leave the exclusion zone.

5.1.31 Safety Check following blow-down 86. The Explosives Engineer will return to the demolished structure and undertake a check to ascertain if all explosive charges have been initiated. The Explosives Engineer will then give the all clear to the control team. Personnel will be given restricted access within the exclusion zone to check on properties for damage, removal of monitoring equipment, inspection of services and to proceed with the clean-up operation

5.1.32 Civilise the Debris Pile 87. To prevent any uncontrolled slide or collapse of the material, 360°excavators will civilise the debris pile by reducing it in height, forming of batters and generally returning the site back to a safe working environment.

5.1.33 Street Cleaning within Site 88. Road sweepers and footpath sweepers will clean and jet wash all surrounding areas that have been significantly affected by the fallout of dust and minor debris.

5.1.34 Lifting of the Exclusion Zone 89. The instruction to lift the exclusion zone will be given by the control team. The area and site will be left in a safe and satisfactory condition before all personnel vacate the site and zone.

6 Environmental Factors 6.1 Traffic and Transport

6.1.1 Introduction 90. Traffic movements requiring consideration for the demolition of Didcot A will be associated with the removal of demolition material from the Site and journeys made by the demolition contractor. A copy of the traffic management plan is provided in Appendix 13. 91. Whilst operational there were approximately 300 people employed at Didcot A power station on a full time basis (including contractors). During outages which occurred every year for up to six months, at least 600 people could be present on site during a working day. In addition, Didcot A was formerly used as a training centre and meeting location by RWE npower with many staff from other locations visiting the Site on a regular basis. It can therefore been seen that when the station was operational there was a significant level of traffic servicing the station with cars and heavy goods vehicles. 92. During the operational running of the station access to the Site was to the south off A4130 Purchas Road and to the North off Margaret’s Road through Milton Park industrial Estate. Access during the demolition works will be from the south of the Site from A4130 Purchas Road, with all vehicular traffic arriving from A34, exiting at the Didcot Junction and travelling along the A4130 arriving at the station entrance. 93. It is expected that during the course of the demolition works traffic levels will rise during certain periods due to the activities on site, but attention has been drawn to these activities to distribute them across the length of the project to reduce any impact. 94. The existing station has a significant coverage of tarmac, concrete and hardstands that provide for all site traffic. The demolition works will retain these hard standing areas during the demolition phase to provide a suitable surface to travel all site vehicles upon. It is not envisaged that a wheel wash will be used regularly as the

existing wearing course is suitable and sufficient to sustain heavy traffic. The roads will be maintained to prevent impact noise from heavy vehicles, including ‘body slap’. The site speed limit will be set at 15mph.

6.1.2 Heavy Goods Vehicles

6.1.2.1 Vehicle Types 95. In order to execute a demolition project, there requires a certain level of heavy goods vehicles that have the capacity to remove heavy loads of steel and concrete; during the works at Didcot A, the following items of plant will be used (Figures 4-6):

Figure 4. Low Loader (21m) – Transport of excavators to and from the Site

Figure 5. Bulker Lorry (13m) – Transport steel off the Site

Figure 6. 8m wheeled vehicle – transport rubbish off the Site

6.1.3 Vehicle Movements 96. All vehicle movements will be pre-planned and scheduled to minimise any potential impact on the local road network. Access for vehicles will be from the A34 exiting at the Didcot Junction (Milton Interchange) and travelling along the A4130 arriving at the station entrance on Purchas Road. These roads are utilised daily by similar sized vehicles. 97. All vehicle movements will be controlled through the use of trained and competent banksmen when entering, exiting or moving around site. 98. All transport movements will be carried out between the hours of 08.00 – 18.00hrs, any movements outside of these times will require permissions from RWE, and local liaison with residents. There are no schools within the vicinity of the site or upon the access route to the road network for site traffic. Due to the use of the site access road, there will be no vehicles waiting on the public highway to enter the site. 99. Where possible, the movement of vehicles off site will be controlled to ease the volume of traffic during peak times. The route from site will use the arterial road network onto the motorway, and will not transit through any villages or industrial surrounding areas. All Coleman & Company vehicles will be fully compliant, road legal and will be compliant with FORS (Fleet Operator Recognition Scheme) 100. During the course of the demolition there will be no requirement for any road closures thus reducing any impact on traffic. However, there may be a requirement for traffic calming/rolling road block measures during the explosive demolition; these will be nominal impact. 101. Demolition arisings will be segregated into material type and processed at source prior to being loaded onto the transport. All carriers will enter the site by passing over a weigh bridge, be loaded and exit via the weigh bridge to give a net exported weight. A detailed, and traceable, record of all material being removed from site will be maintained at all times. Transfer Notes/Consignment Note must be completed, loads sheeted and vehicle inspected for any loose material prior to leaving site. 102. There shall be no waiting on the main or public roads or any bridges which may hinder access by members of the public or those accessing the live parts of the site. 103. All waste vehicles shall be enclosed or sheeted with debris netting depending upon the vehicle. 104. A competent banksman shall be utilised for traffic and plant movements within the demolition site and shall also ensure that the entrance gates to the demolition site remains secured at all times. 105. Designated traffic routes shall be established and maintained throughout and shall be reviewed as the project progresses to ensure the safest and most appropriate access is maintained.

6.1.4 Abnormal Loads 106. During the course of the works there will be a number of abnormal movements required. The movement of an abnormal load will be covered under the submission and approval of a movement order detailing the significant of the abnormal load.

The movement order will identify the route into the Site that the driver must take in order to arrive at the Site. All abnormal load notifications will be submitted to the Highways Authority 5 days prior to its arrival on site, and the designated route into the Site will take into account any bridges or roads that have any restrictions. 107. Many abnormal loads are accompanied to and from the Site with an “escort” vehicle that will assist the load through sensitive areas, built up areas, town centres or motorways. Transport of an abnormal load can be carried out to minimise the disruption to local communities or disruption on the local road network at times that can be determined. The route for abnormal loads will exit off the A34 southbound, exiting at Didcot Junction, travel along A4130, taking a left at roundabout arriving at entrance to station off Purchas Road. There is not envisaged any restrictions for this route and all bridges have been assessed for weight restrictions

6.1.5 Personnel on Site

6.1.5.1 Level of personnel 108. Over the course of the demolition project there will be fluctuations in the level of resources that will be required on site. It is known that year one of the project will yield the highest level of resources, whilst levelling off in years two and three. It is envisaged that in year one the maximum level of resources that will be required could amount to 150 people on site. This peak level of resource would be required from May 2014 and would be expected to last until October 2015. After October 2015 the level of resource required in year two and three will diminish to a sustainable level of 75 people.

6.1.5.2 Parking Arrangements 109. With any development there is often an issue for suitable off-site parking in order to reduce any impact to the road network. Car parking outside the main gate adjacent to security will be identified for the collective parking of all personnel vehicles. This facility allows all vehicles to park without impacting the surrounding road network and without interfering with the movement of vehicles in and out of site.

Off-site parking is provided for all personnel cars and is situated in front of the security gate

Figure 7. Parking area for personnel vehicles

6.1.6 Mitigating Proposals 110. Wherever possible alternative proposals will be considered to mitigate adverse impact resulting from any significant increase in traffic to the area. Car share schemes will be encouraged to help reduce the number of vehicles travelling to the Site and to reduce the associated carbon footprint. Efforts will be made to reduce the number of vehicles entering the road network by utilising coaches/mini- bus/shuttle services to transport large numbers of people with minimal impact. 111. Where personnel travel from outside the local area; they will be collected from their local accommodation and transported to Site by mini bus/coach/van. Where possible staff will be recruited from the local area to support the local economy, reduce travel times, and minimise impact on the wider road network.

6.1.7 Previous Traffic Impact 112. Prior to closure in March 2013 there was a considerable amount of traffic associated with the day to day operation of Didcot A power station. In order to establish the potential impact of the demolition works on the local road network it can be compared with the traffic generated during the operational period of the power station. 113. Daily logs have previously been recorded at the gatehouse and provide an indication of the traffic levels generated during the operational period. An extract of the log counts (one direction) are provided below (calendar month, October 2012). These counts identify the total number of vehicles (cars, vans, lorries and heavy goods vehicles) entering the Site on a daily basis. The data is significant as it indicates the impact that the operational station had on the local road network on a daily basis and was recorded over a 7 day working week. It is not envisaged that the demolition works will have near the level of impact that was recorded.

Date Traffic Count Monday 01 October 2012 448 Tuesday 02 October 2012 461 Wednesday 03 October 2012 449 Thursday 04 October 2012 421 Friday 05 October 2012 413 Saturday 06 October 2012 143 Sunday 07 October 2012 119 Monday 08 October 2012 427 Tuesday 09 October 2012 460 Wednesday 10 October 2012 445 Thursday 11 October 2012 435 Friday 12 October 2012 381 Saturday 13 October 2012 165 Sunday 14 October 2012 143 Monday 15 October 2012 410 Tuesday 16 October 2012 477 Wednesday 17 October 2012 473 Thursday 18 October 2012 412 Friday 19 October 2012 420 Saturday 20 October 2012 160 Sunday 21 October 2012 141 Monday 22 October 2012 397 Tuesday 23 October 2012 394 Wednesday 24 October 2012 422 Thursday 25 October 2012 414 Friday 26 October 2012 411 Saturday 27 October 2012 198 Sunday 28 October 2012 127 Monday 29 October 2012 418 Tuesday 30 October 2012 459 Wednesday 31 October 2012 437 Table 1. Extract of Recorded Data from Gate Logs – October 2013

6.1.8 Potential Traffic impact – demolition 114. The potential impact of the demolition works on the surrounding road network can be determined by reviewing the programme of activities planned on site. The following data has been extracted from the programme to demonstrate the level of impact in terms of number of additional vehicles on the local road network. When reviewing the demolition programme consideration was given to activities that would have an impact on local network; and efforts will be made to spread these activities over the duration of the works. The following data is based on calculating the overall weight of steel within the project, identifying the area within the project it derives from, and anticipating the removal of the material from the Site. The information is based on a load of steel removed from the Site being an average weight of 30t across all axils.

Total Weight of No. of Bulker Vehicles Contract Period Duration Material per week May 2014 – September 2014 5 months 5000t 6-10 October 2014 – April 2015 7 months 28000t 30-40 May 2015 – August 2015 4 months 0t September 2015 – August 2016 12 months 45000t 30-50 Table 2. Bulker Vehicle movements anticipated throughout the project duration. 115. During the course of the project other vehicle movements will include:- 1. Abnormal Loads – Anticipated levels 60 loads (over course of project) 2. Delivery/Collection of equipment – Anticipated levels 50 loads (over course of project) 3. Visitors to the Site – Anticipated 100 - 150 No. (over course of project) 4. Site Personnel – Anticipated levels 60 - 80 No. daily year 1, 40 - 60 No. daily Years 2 & 3

6.1.9 Site Management

6.1.9.1 Site Access routes 116. Primary access and on-site transport routes are shown in Figure 8

Figure 8. Site access and on-Site transport routes

117. During the demolition works all vehicles or persons entering the Site must be booked in advance. 118. All contractors’ access to the Site will be via the main gates – accessed off the A4130. All vehicles and persons entering the Site will report to the Security Gate and present their site pass for inspection. Infrequent or special deliveries will be

escorted to and from the area of works. Drivers will not be permitted to exit their vehicles whilst on site. If the driver is required to unload or assist in the delivery/collection they will attend a site induction prior to gaining access.

6.1.9.2 Working under Cables 119. There are High Voltage overhead cables on site that will remain live throughout the demolition project. As far as reasonably practicable transit routes and site activities will be designed to avoid the need to work near or pass below live services. All redundant services are scheduled to be removed; any cables not clearly identified as dead will be taken as being live until confirmed otherwise. Where transit routes pass below live cable the controls set out in the HSE Guidance NoteGS6 will be enforced.

Figure 9. Control measures for transit routes below live cables

120. All plant is required to have booms, masts or tipper bodies in the lowered position while passing below the live service. Access roads are required to be firm, level, and at right angles to the overhead service.

Figure 10. Example of rigid goal posts and barriers for sites where plant pass under a line

121. It is acknowledged that since the closure of the station in March 2013, a significant volume of traffic has been removed from the local road network. During the demolition of the station there will be an increase in traffic in the area, however the impact on the local road network is likely to be less than that during the operational phase. The maximum of people travelling to the Site during the demolition phase will be significantly less than during the operation phase of the power station. 122. It is proposed to retain as much of the demolition arisings on the Site as possible for re-use in the future site redevelopment. Any material removed from the Site during demolition (e.g. metals, asbestos) will be taken away by lorry. It is anticipated that transport movements during the demolition process are unlikely to be considered significant, as they will be less than those generated by the former operational power station. 123. The proposed mitigation measures such as staggering heavy goods vehicle movements off site throughout the working day as much as possible, off road parking, employment of local people, use of multi-people vehicles will ensure that any impact on the local road network is minimised. It is anticipated that there will be no significant impact to the surrounding road network during the demolition works.

6.1.9.3 Additional Controls during blowdown 124. During the demolition works there will be a number of explosive demolitions to structures. As part of this process there will be a need to implement specific Traffic Management Schemes to the surrounding road network. The demolition company will employ an accredited traffic management company to review, submit and

implement an approved traffic management plan for the works. The plan would include temporary road closures to surrounding roads to restrict or eliminate traffic. 125. A management plan will be submitted to Oxford County Council eight weeks prior to the planned works and will be subject to consultation and approval. On the day of the blow-down all of the traffic management will be managed & implemented by a competent traffic management company, and overseen by the demolition contractor.

6.2 Noise, Vibration, and Dust

6.2.1 Baseline Noise Data 126. Prior to commencement of demolition a baseline noise survey will be conducted at a number of locations surrounding the Site. The proposed monitoring locations have been agreed with the Local Authority Environmental Protection Officers and are as follows (see Figure 11): • M1 High Street, Sutton Courtenay • M2 Harwell Road, Sutton Courtenay • M3 Appleford, Crossing Main Road, Appleford • M4 Mendip Heights, Didcot • M5 Foxhall Manor Park, Didcot

127. The baseline monitoring results will be made available to the LPA.

6.2.2 Predicted Noise 128. The works associated with the demolition of Didcot A Power Station will take place in zones across the Site and include use of large items of demolition and mobile plant that will have capacity to produce noise during operation. There is therefore potential for these works to provide a temporary noise impact on the existing environment around Didcot Power Station. Temporary vibration impacts may also arise from demolition works, particularly those associated with any required blasting operations. 129. Predictive noise calculations have been conducted in accordance with the requirements of BS 5228-1:2009. Information regarding the variety and numbers of equipment used for the demolition works, in addition to the ‘on times’ (i.e. % of time that each item will be in active use) has been used to inform the predictive calculations. Standard noise levels (as a sound power level), as presented in BS5228 have been used where relevant. In many cases the sound power levels for processes and equipment used during the demolition as reported are not stated within BS5228. Where this is the case estimations of the sound power have been made based on similar equipment/processes. 130. The receptor locations are listed below (see Figure 12): • R1 Sutton Courtenay Recreation Ground • R2 High Street, Sutton Courtenay (South End)

• R3 Appleford, Main Road • R4 Didcot Field (Great Western Park) • R5 Harwell • R6 Willowbrook Estate (Didcot) • R7 Foxhall Manor Park

131. Distances between the site of demolition and the sensitive receptors have been mapped using OS digital mapping software. 132. Barrier effects (full and partial), have been included within the calculations based on the schedule of works for demolition. Where a barrier has been removed during the progress of demolition, this has been considered within the calculations for subsequent zone and adjacent zone activities. 133. The results presented are LAeq over the duration of activity. 134. The results do not take into consideration the ‘bangs and clatters’ etc but are a representation of the constant noise generated as specified in BS 5228-1:2009. 135. Using the guidance within BS 5228-1:2009 for a residential area during daytime (i.e. 0700 - 1900 hrs), the predicted noise level of the activities combined with the ambient noise level should not be at or above 65 dBA. 136. The predicted noise results have been calculated using information provided regarding each of the activities taking place in the different zones. For each activity the number and type of plant was determined along with the duration of the activity and percentage ‘on time’ for the plant/equipment during the working day. The summary tables provided below therefore contain the final LAeq for, in most cases, a combination of activities. The single title associated with the various LAeq (the left hand column describing an activity), may therefore describe a number of activities taking place at the same time (see Appendix 14 for further explanation). 137. The predicted noise results at the seven receptors for the various stages of demolition within Zone 1 (Southern Cooling towers) are presented in Table 3 below. The zones referred to in the following tables are shown on Figure 3.

R1 R2 R3 R4 R5 R6 R7 ZONE 1- Activity (dBA) (dBA) (dBA) (dBA) (dBA) (dBA) (dBA) De-watering pumps 32.3 34.9 34.0 34.6 36.5 34.9 39.0 De-watering and drilling legs 32.7 34.8 34.4 40.7 36.9 35.6 38.0 Drilling shell 32.6 34.7 34.3 39.7 36.8 35.8 39.3 Excavation of ground 33.6 35.8 35.3 45.5 37.9 37.1 42.4 Excavator with muncher 35.6 37.8 37.3 50.4 40.0 39.9 46.4 Removal of wood &compactor 33.5 35.7 35.2 41.2 37.0 37.0 40.6 Drilling shell 32.6 34.7 34.3 39.7 36.8 35.8 39.3 Processing and crushing 35.4 37.6 37.0 45.0 39.8 39.6 46.0 Table 3. Zone 1 Predictive Noise Results

138. The most sensitive receptor in the example above is R4 (Didcot Field – Great Western Park) to the south and the closest receptor. The highest predicted noise

level is 50.4 dBA during processing and crushing activities. There is no barrier between the noise and the receptor in the calculation. 139. The predicted noise results at the seven receptors for the various stages of demolition within Zone 2 (Northern Cooling Towers) are presented in Table 4.

ZONE 2 - Activity R1 R2 R3 R4 R5 R6 R7 (dBA) (dBA) (dBA) (dBA) (dBA) (dBA) (dBA) De-watering pumps 30.0 33.6 18.6 29.9 13.8 17.9 20.6 De-watering and drilling legs 37.0 40.6 35.5 26.8 20.8 24.9 27.5 Drilling shell 31.0 34.3 29.6 31.1 19.8 23.9 26.6 Excavation of ground 42.0 45.6 40.6 31.9 25.8 29.9 32.6 Excavator with muncher 47.0 50.6 45.6 36.9 30.8 34.9 37.6 Removal of wood &compactor 37.1 40.7 35.7 32.0 25.9 30.0 32.7 Drilling shell 31.0 34.3 29.6 31.1 19.8 23.9 26.6 Processing and crushing 46.5 50.2 44.6 36.4 30.4 34.4 37.1 Table 4. Zone 2 Predictive Noise Results

140. The two main receptors here are R1 (Sutton Courtenay Recreation Ground) and R2 (High Street, Sutton Courtenay (South End)) to the north-east. The activity calculated to present the highest noise level is the use of the excavator with the muncher for both R1 and R2 (47.0 dBA and 50.6 dBA respectively). 141. The predicted noise results at the seven receptors for the various stages of demolition within Zone 3 Chimney Stack (B23) are presented in Table 5 below.

R1 R2 R3 R4 R5 R6 R7 ZONE3-Activity (dBA) (dBA) (dBA) (dBA) (dBA) (dBA) (dBA) Clearance/burning 23.3 25.9 25.2 41.0 31.7 27.8 32.6 Clearance/loading-excavator 24.4 27.0 26.3 42.2 32.8 28.9 33.7 Blast prep-drilling 20.9 23.5 22.9 38.7 29.4 25.5 31.6 Pre-weakening 20.3 22.9 22.2 38.1 28.7 24.8 27.5 Processing arisings 28.7 31.3 30.6 46.5 37.2 33.2 35.9 Crushing Arisings 29.3 31.9 31.2 47.1 37.8 33.8 36.5 Table 5. Zone 3 Predictive Noise Results (Chimney Stack)

142. The most sensitive receptor here is R4 (Didcot Field) to the south and the closest receptor. The highest predicted noise level is for the processing and crushing of arisings with results of 46.5 dBA and 47.1 dBA respectively. There is no barrier between the noise and the receptor in the calculation. 143. The predicted noise results at the seven receptors for the various stages of demolition within Zone 3 Hydrogen Stores and Nitrogen Tank (B42 & 43) are presented in Table 6 below.

R1 R2 R3 R4 R5 R6 R7 ZONE3-Activity (dBA) (dBA) (dBA) (dBA) (dBA) (dBA) (dBA) Cutting tanks with shears 36.4 37.6 36.8 46.0 45.5 39.6 46.2 Burning/breaking columns 31.4 34.0 33.1 27.6 35.6 33.9 36.7 Table 6. Zone 3 Predictive Noise Results (Hydrogen Stores)

144. The most sensitive receptor here is R4 (Didcot Field) to the south and the closest receptor and R5 Harwell (Didcot). The highest predicted noise level is for the cutting of the tanks using shears with results of 46.0 dBA and 45.5 dBA respectively. There is no barrier between the noise and the receptor in the calculation. 145. The predicted noise results at the seven receptors for the various stages of demolition within Zone 3 Turbine Hall are presented in Table 7 below

ZONE3-Activity R1 R2 R3 R4 R5 R6 R7 (dBA) (dBA) (dBA) (dBA) (dBA) (dBA) (dBA) Cladding removal 35.5 32.6 42.5 46.6 32.5 34.5 36.9 Processing arisings 30.0 27.1 36.9 41.1 27.0 29.0 32.7 Creation of hard corebed 31.4 28.5 38.4 42.5 28.4 30.4 34.1 Moving/processing material 42.3 39.4 49.3 53.4 39.3 41.3 45.0 Demoprep-burning 33.0 30.1 40.0 44.1 30.0 32.0 35.7 Crushing arisings 34.6 31.7 41.5 45.7 31.5 33.6 37.3 Structural preparation 42.8 39.9 49.8 53.9 39.8 41.8 45.5 Processing arisings 46.0 43.1 52.9 57.1 43.0 45.0 48.7 Table 7. Zone 3 Predictive Noise results (Turbine Hall)

146. The most sensitive receptor here is R4 (Didcot Field) to the south and the closest receptor. The highest predicted noise level is for the processing of arisings with results of 57.1 dBA. There is no barrier between the noise and the receptor in the calculation. 147. The predicted noise results at the seven receptors for the various stages of demolition within Zone 4 are presented in Table 8 below. R1 R2 R3 R4 R5 R6 R7 ZONE 4 - Activity (dBA) dBA) (dBA) (dBA) (dBA) (dBA) (dBA) Demolition of B11/18/12/55 37.4 29.5 39.4 33.5 24.4 31.5 35.2 Processing of arisings 39.0 31.1 40.9 35.1 26.0 33.0 36.8 Demolition of B14/16/44 37.4 29.5 39.4 33.5 24.4 31.5 35.2 Processing of arisings 38.8 30.9 40.7 34.9 25.8 32.8 36.5 Demolition of B15/19 37.4 39.5 39.4 43.5 34.4 41.5 45.2 Processing of arisings 38.9 40.9 40.7 44.9 35.8 42.8 46.5 Table 8. Zone 4 Predicted Noise impacts

148. The most sensitive receptor here is R4 (Didcot Field) to the south and the closest receptor. The highest predicted noise level is for the processing of arisings with a result of 44.9 dBA. There is no barrier between the noise and the receptor in the calculation.

149. The predicted noise results at the seven receptors for the various stages of demolition within Zone 5 are presented in Table 9 below.

R1 R2 R3 R4 R5 R6 R7 ZONE5-Activity (dBA) (dBA) (dBA) (dBA) (dBA) (dBA) (dBA) Structural prep 29.6 32.3 29.9 46.8 37.2 32.0 36.4 Demolition coal unload house 31.2 33.9 31.6 38.5 28.8 33.6 38.0 Processing and clearing 26.5 29.2 31.8 43.7 34.1 28.9 33.3 Structural Preparation 29.4 32.1 29.5 46.6 37.0 31.8 36.2 Demolition of B50/22 30.7 33.4 31.0 37.9 28.2 33.0 37.4 Processing and clearing 22.7 25.4 23.1 39.9 30.3 25.1 29.5 Table 9. Zone Predicted Noise Impacts

150. The most sensitive receptor here is R4 (Didcot Field) to the south and the closest receptor. The highest predicted noise level is for the structural preparation with a result of 46.8 dBA. There is no barrier between the noise and the receptor in the calculation. 151. The predicted noise results at the seven receptors for the various stages of demolition within Zone 6 are presented in Table 10 below.

ZONE6-Activity R1 R2 R3 R4 R5 R6 R7 (dBA) (dBA) (dBA) (dBA) (dBA) (dBA) (dBA) Removal of pipework 31.6 34.2 33.5 49.5 39.7 36.3 41.3 Shearing/processing 31.6 34.2 33.5 49.5 39.7 36.3 41.3 Breaking walls/processing 42.1 44.7 44.1 60.0 50.2 46.8 51.8 Table 10. Predicted Noise Impacts

152. The most sensitive receptor here is R4 (Didcot Field) to the south and the closest receptor. The highest predicted noise level is for the breaking of walls and processing with a result of 60.0 dBA. There is no barrier between the noise and the receptor in the calculation. This activity generates the highest predicted noise levels for all of the receptors.

6.2.3 Summary of predicted noise impacts 153. None of the predicted noise levels from the activities reported give rise to a level of noise at the various specified receptors above the threshold of 65 dBA as stated within BS 5228-1:2009. 154. In order to identify the periods of highest noise and the relevant sources, the information has been presented below to indicate the highest predictive noise calculated for each receptor for each zone of demolition and the time at which this will occur. 155. The highest predicted noise for each zone relative to the receptor only has been used. It should be noted that the highest noise generated in Zone 1 was for a 360° with the use of a ‘muncher’. This activity is programmed to last one day only. Processing of the arisings in all cases was the second highest predicted noise and programmed over an approximate 6 - 8 week period. Processing of arisings is the activity that has therefore been used for this zone for all receptors.

156. Additionally for Zone 4 there were several activities where the predicted noise would be around the same level at some receptors. In this case each activity has been included (Receptors 1 & 3). 157. In addition to the ongoing general demolition activities there will be a number of explosive demolition events. For example the three cooling towers situated to the south of the Site will be imploded during the course of a single blowdown event. A decision to implode all three cooling towers simultaneously (rather than as separate events) will significantly reduce the impact of noise. The initial impact will be during the initiation of the structures which is over a 2 second period; the collapse of the structures will then generate noise over a period of approximately 3 seconds. This culminates in a short impact over a period 5 seconds. As the noise is at a high level it will quickly be dissipated. The impact of noise during the implosion is unavoidable but minimal as it is over a significantly short period. Local businesses and resident will be notified in advance of planned blowdown events.

Receptor 1 – Sutton Courtenay Recreation Ground

Figure 13. Predicted Noise Levels at Receptor 1 and associated duration

Receptor 2 – High Sutton Courtenay (South End)

Figure 14. Predicted Noise Levels at Receptor 2 and associated duration

Receptor 3 – Appleford Crossing

Figure 15. Predicted Noise Levels at Receptor 3 and associated duration

Receptor 4 – Didcot Field

Figure 16. Predicted Noise Levels at Receptor 4 and associated duration

Receptor 5 – Harwell

Figure 17. Predicted Noise Levels at Receptor 5 and associated duration

Receptor 6 – Willowbrook Estate (Didcot)

Figure 18. Predicted Noise Levels at Receptor 6 and associated duration

Receptor 7 – Foxhall Manor Park

Figure 19. Predicted Noise Levels at Receptor 7 and associated duration

6.2.4 Noise Control Measures 158. Due to the nature of demolition activities, both general and explosive demolition, noise can be expected to be generated by a number of sources with more than one source active at any one time. Although the predicted noise levels given above do not exceed the recommended level there are good practice measures which will still be put in place during the demolition works. In line with the requirements of BS 5228-1:2009 noise impacts associated with the demolition activities will be minimised as far as reasonably practicable. The management of noise to suppress the levels shall be via a number of initiatives including: • Determining the location and orientation of plant as far as practical in order to minimise the impact upon sensitive receptors • Stock piles and arisings will be used (where practicable) to form noise barriers to provide noise attenuation for sensitive locations. For each crushing operation, the location and orientation of equipment, stockpiles and arisings will be determined following consideration of noise sensitive receptors and other barrier effects. • Maintaining plant and equipment in good condition, being checked daily before use and having undergone servicing and maintenance

• Noise assessments in terms of expected levels of noise from an environmental point and of view and the impact upon human health are undertaken • Noisy activities shall not commence prior to 7.30 am to prevent any adverse impact upon sensitive receptors

159. Where necessary ear defenders shall be worn if the above do not reduce noise to below the lower noise action level to minimise the impact on human health. 160. Super silenced generators are used to minimise the potential for noise. All plant and equipment is regularly serviced and undergoes a maintenance regime which aids in controlling noise levels. 161. The noise (and dust) mitigation measures will form an integral aspect of the safe method of work. It is noted however that bangs and clatters can have an impact and would be audible during site visits and monitoring periods. Controls will be identified and implemented at site level to minimise the impact or prevent the activities where appropriate. Details of the actions taken will be noted to provide a record for future reference. Follow up reviews and/or monitoring will be undertaken to determine whether any additionally implemented controls achieve the required reduction in noise level and noise characteristics such as bangs and clatters. 162. Mitigation measures include preventing revving and idling; no use of the plant/vehicle horn; maintenance of site roads to prevent ‘body slap’; no dropping of materials to prevent impact bangs and clatters; working only to agreed hours of work; use of buildings / material stockpiles and orientation of plant so far as possible to act as screens and barriers for noise and dust. All plant and vehicles are serviced on a regular basis and are inspected by the operator / driver prior to each usage. 163. The traffic management plan within the site boundary has been developed to minimise reversing (e.g. allowing for turning circles). The use of reversing alarms will be minimised, however reversing will be required when vehicles need to get into position for loading etc.

6.2.5 Ongoing Monitoring 164. Noise monitoring will be undertaken throughout the project following the requirements of BS5228: 2009 Part 1: Code of Practice for noise and vibration control on construction and open sites. 165. Monitoring will be undertaken by independent competent consultants on behalf of the demolition contractor using a Type I noise monitor. The noise monitor will be calibrated before and after each one hour monitoring period. The noise levels will be measured as LAeq and LA90. All Noise monitoring will be undertaken during the working day. 166. Noise monitoring will be undertaken throughout the phases of work and will take into consideration the activities which are active to ensure that they are included in

the monitoring regime. Typically more than one activity will be included in the monitoring period. Not all monitoring locations will be in use at any one time; it will depend on the activities taking place and safe access to the monitors. The monitoring locations will all be positioned within the Site and will include positions close to the boundary of Didcot A and National Grid such that levels which may be experienced beyond the site boundary can be determined. 167. The positions for noise monitoring will change as the activities on site vary but will be undertaken at positions which are in the ‘free field’ at a height of approximately 1.3m from the ground. The positions chosen will typically be located close to the Site boundary with sensitive receptors and / or within the demolition Site boundary, surrounding active zones of demolition work. The frequency of noise monitoring will be dependent upon the length of the programmed work activities within one or more zone to obtain the worst case scenario for the noise levels. 168. The results obtained will be used to determine whether the predictions given in section 6.2.2 are correct. The data collected will be reviewed to determine any peaks or additional noise sources which may occur, and to ascertain whether the noise control measures implemented are successful. Where the predicted levels are exceeded, or the measured levels are higher than expected, the cause(s) will be investigated. The noise level at which this process is initiated will be agreed with the LPA. Additional controls may be implemented to reduce the noise at source where possible or determine and acoustic controls which may be required. 169. In the event that exceptionally high noise levels are recorded due to an incident, unforeseen act or an underestimation of the expected noise levels the Environmental Protection Officer at the Vale of White Horse District Council will be contacted to explain the events or circumstances regarding a peak in noise levels. This is a pre-emptive measure that will forewarn Vale of White Horse DC prior to recording any public complaints that may occur as a result of the incident.

6.2.6 Vibration impacts 170. In general, the use of explosives for the demolition of structures is liable to give rise to both ground and airborne vibration. Detonation of the explosive itself may generate ground vibration, although it is usual for the majority of explosive to be located within the structure and above ground level and hence this source of vibration is generally minimised. 171. It is usually the airborne vibration or air overpressure generated by the explosive that is of most significance owing to the fact that the individual charges, albeit relatively small, are often not able to be totally confined and may also be associated with exposed lengths of detonating cord. Once detonation occurs, the structure itself as it impinges on the ground will be a further source of vibration. In this case the vibration will be predominantly generated within the ground with any air vibration of a minimal magnitude. 172. The structures to be demolished by explosive means include; • Cooling towers - each approximately 105 metres in height and 8500 tonnes in weight.

• Stack - approximately 200 metres in height and 28700 tonnes in weight. For the purposes of the predictive calculations it was assumed that the chimney would be demolished in a south westerly direction towards the coal storage area. More recent investigations suggest that a north westerly direction may be preferred, and as such the predictive calculations will be updated prior to demolition. • Boiler numbers 1 to 4 - each approximately 50 metres in height and 12000 tonnes in weight. The demolition of boilers 1 to 4 has been considered as separate discrete events for the predictive calculations presented in Appendix 15.

173. The main vibration sensitive locations in the vicinity of the Site are:- i. Didcot B CCGT ii. Gas Receiving Facility iii. 400 KV Substation iv. Digipress Limited/Warehousing v. Gas Turbine House vi. Cold Water Pump House vii. Railway Line

6.2.7 Ground vibration 174. Ground vibration can be expected from a number of sources including general movement of plant and vehicles and mechanical demolition of structures; through to ground vibration resulting from explosive demolition. 175. The explosive demolition can be expected to give rise to vibration levels which may cause no damage through cosmetic hairline cracks up to minor and major / structural damage. In addition the impact of falling demolition debris will give rise to ground vibration. 176. When defining damage to residential type structures the following classifications are used (further information can be found in Appendix 15):- • Cosmetic or threshold - the formation of hairline cracks or growth of existing cracks in plaster, drywall surfaces or mortar joints. • Minor - the formation of large cracks or loosening and falling of plaster on drywall surfaces, or cracks through bricks/concrete blocks. • Major or structural - damage to structural elements of a building.

177. The level of ground vibration may be limited or enhanced by the ground conditions and geology of the area.

6.2.8 Predicted Ground Vibration Levels 178. A typical ground vibration record for structures is likely to comprise of a complex series of waveforms. The first event is generated by the detonation of the explosives

and this is followed by a series of events generated by the structures collapse upon the ground. The first event is usually characterised by its higher frequency content and shorter time duration, with the second and subsequent events being of greatest magnitude. 179. From the weight and height of the structures together with details regarding the collapse mechanism, the maximum potential energy available upon impact has been calculated for the structures at Didcot. The vibration predictions have been undertaken using empirical relationships derived from previously acquired data from the demolition of similar structures taking into account the specific ground conditions. This has allowed the best estimate and worst case scenarios to be made of ground vibration levels. These predictions make appropriate allowances for the collapse mechanism, the ground conditions, the distance from the impact, the mass of the structure, energy of impact and energy of explosive initiation.

Single Tower Two Towers Ground Vibration Level Ground Vibration Level Location (mms-1) (mms-1) Worst Case Worst Case Most Likely Most Likely Scenario Scenario 1. Didcot B CCGT 0.4 1.0 0.5 1.5 2. Gas Receiving Facility 0.2 0.5 0.3 1.0 3. 400kV Substation 0.4 1.0 0.5 1.5 4. Digipress 3.0 6.5 3.5 8.0 Limited/Warehousing 5. Gas Turbine House 0.6 1.5 0.7 2.0 6. Cold Water Pump House 0.7 2.0 0.9 2.5 7. Railway Line 1.4 3.5 1.8 4.5 Table 11. Predicted Ground Vibration Levels: Southern Cooling Towers

Three Towers Ground Vibration Level Location (mms-1) Worst Case Most Likely Scenario 1. Didcot B CCGT 3.5 8.5 2. Gas Receiving Facility 7.0 14.0 3. 400kV Substation 4.0 9.0 4. Digipress Limited/Warehousing 0.3 1.0 5. Gas Turbine House 1.5 4.0 6. Cold Water Pump House 1.5 4.0 7. Railway Line 0.3 1.0 Table 12. Predicted Ground Vibration Levels: Northern Cooling Towers

180. Further predictions for ground vibration levels associated with the main stack and boiler house are presented in Appendix 15. 181. Table 11, details the predicted ground vibration levels associated with the demolition of the southern cooling towers for (i) a single cooling tower and (ii) two cooling towers. 182. Since the initial vibration assessment was completed the proposed approach for demolition of the southern cooling towers has been further assessed. It is now considered likely that all 3 towers will be demolished on the same day rather than conducting a ‘test blast’ on a single tower in the first instance. Given there is a minimum two second delay between the initiation of consecutive cooling towers and with sight of historical data; the increase in vibration levels for all three cooling towers compared to two cooling towers is unlikely to be significant. Similarly, demolition of the boiler house is likely to take place as a single event rather than in phases. An updated vibration assessment will be completed in advance of demolition taking place and the subsequent report will be made available to the LPA.

6.2.9 Air over pressure 183. Whenever an explosive is detonated, airborne pressure waves are produced from five main sources:- i. Material displacement. ii. Ground induced airborne vibration. iii. Release of gases through fissures. iv. Release of gases through stemming. v. Insufficiently confined explosive charges.

184. Meteorological factors over which an operator has no control can influence the intensity of air overpressure levels at any given location. Thus, wind speed and direction, temperature and humidity at various altitudes can have an effect upon air overpressure. 185. Air over pressure is caused by air waves during explosive demolition which may be felt and heard depending upon the frequency. This may be increased due to the air displacement caused by buildings as they collapse and the direction in which the structure falls. 186. The levels depend upon the quantity and volume of the explosives used and can be affected by the meteorological conditions such as wind speed; wind direction; air temperature and humidity and temperature inversions. The levels may also be influenced by the presence of other buildings and other explosive demolition taking place concurrently. 187. Comprehensive investigations into the nature and effects of air overpressure with particular reference to its damage potential have been undertaken by the United States Bureau of Mines who have also reviewed all other published data on this subject (R.I. 8485, 1980). The weakest parts of most structures that are exposed to air overpressure are windows. Poorly mounted, and hence pre-stressed windows

might crack at around 150 dB (0.1 p.s.i.) with most cracking at 170 dB (1.0 p.s.i.). Structural damage can be expected at 180 dB (3.0 p.s.i.).

6.2.10 Predicted Levels: Air over pressure 188. The maximum air overpressure levels are generated by the initiation of the explosives with the amount of energy dissipated based on the explosive charge weight together with its location, degree of confinement and method of initiation. 189. For the demolition of any structure the charges can be considered to have limited confinement as their sole function is to break the material in which they are confined. 190. The air overpressure predictions are derived from an extensive database taking into account the conditions specific to this demolition. Predictions for the southern and northern cooling towers are provided in the tables below, with further predictions provided in Appendix 15.

Single Tower Two Towers Air Overpressure Level (dB) Air Overpressure Level (dB) Location Worst Case Worst Case Most Likely Most Likely Scenario Scenario 1. Didcot B CCGT 120 130 122 132 2. Gas Receiving Facility 115 125 117 127 3. 400kV Substation 120 130 122 132 4. Digipress 135 145 137 147 Limited/Warehousing 5. Gas Turbine House 125 135 127 137 6. Cold Water Pump House 125 135 127 137 7. Railway Line 130 140 132 142 Table 13. Predicted Air Overpressure Levels: Southern Cooling Towers

Single Tower Air Overpressure Level (dB) Location Worst Case Most Likely Scenario 1. Didcot B CCGT 135 145 2. Gas Receiving Facility 140 150 3. 400kV Substation 135 145 4. Digipress Limited/Warehousing 112 125 5. Gas Turbine House 130 140 6. Cold Water Pump House 130 140 7. Railway Line 115 125 Table 14. Predicted Air Overpressure Levels: Northern Cooling Towers

6.2.11 Discussion of Vibration Predictions 191. The worst case predicted vibration level at the operational Didcot B CCGT station is 8.5 mms-1 associated with the demolition of the three northern cooling towers. Such a level is considered to be safe with respect to safeguarding the operational requirements of this facility. 192. The worst case predicted vibration level at the gas receiving station is 14 mms-1 associated with the demolition of the three northern cooling towers. Such a vibration level is below the guide value given within BS 5228-2: 2009 for pipework of 30 mms-1. 193. The 400 KV substation is situated to the north east of the Site. The predicted worst case vibration level at the 400 KV switchgear compound is 9 mms-1 associated with the demolition of three northern cooling towers. Previous studies of vibration sustained by electrical substation relays have been guided by an acceleration limit of 0.5 g for single component transient excitation. With a predominant frequency of 20 Hertz, the predicted maximum vibration level at the 400 KV switchgear compound corresponds to an acceleration of 0.17 g which is well below the 0.5 g limit. 194. The worst case predicted vibration level at the industrial buildings including Digipress Limited and warehousing to the south east of the Site is 8 mms-1 associated with the demolition of the two southern cooling towers. Such a vibration is safe with respect to safeguarding the structural integrity of an industrial type building. 195. The worst case predicted vibration levels at the gas turbine house and the cold water pump house are 5.0 mms-1 associated with the demolition of the main stack. Such a level is considered to be safe with respect to safeguarding the operational requirements of such facilities. 196. With regard to the railway line to the south, the worst case vibration level prediction is 4.5 mms-1 associated with the demolition of the three southern cooling towers, which is considered to be a safe level. 197. The air overpressure predictions are all relatively high but this is usual and generally accepted for demolitions involving explosives. Levels of this order and higher have been monitored for many other demolitions with no damage being occasioned. The maximum predicted air overpressure level is 150 dB at the gas receiving facility associated with the demolition of the three northern cooling towers. 198. The maximum predicted air overpressure at the operational Didcot B CCGT station is145 dB associated with the demolition of the three northern cooling towers. Such levels are considered to be safe with respect to safeguarding the integrity of such structures.

6.2.12 Control Measures (vibration and air over pressure) 199. In summary, the following control measures will be implemented: • Dilapidation surveys to be undertaken prior to demolition

• Ground borne and air over pressure measurements during explosive demolition • Protection of sensitive structures where appropriate • Explosive demolition to fall in specified direction as far as possible away from vibration sensitive receptors without causing other safety issues • Protection from air over pressure for windows as appropriate • Location and processing associated with general demolition in terms of proximity to sensitive receptors shall be taken into consideration • Plant and machinery shall be serviced and well maintained to minimise the likelihood of vibration with daily inspections • Where appropriate, protection for underground services shall be afforded utilising road plates or similar to spread the load

200. From the predictions and previous experience of demolitions such as this the following conclusions can be drawn:- 1. The levels of ground vibration predicted are of magnitudes that are considered safe with respect to the integrity of the structures considered. 2. The air overpressure levels predicted are relatively high but are considered to be entirely safe with respect to the possibility of damage at the locations of concern. 201. The predictions are based upon out-line demolition method statements and therefore the predicted vibration levels are indicative. Further predictions will be made when detailed method statements are available, the results of which will be provided to the Local Authority. Vibration recordings will also be undertaken during the demolition at locations representative of those identified in the above tables.

6.2.13 Dust 202. Dust can be expected to be created as a result of general demolition techniques and through explosive blow-down. 203. The management of dust will take account the impact of dust for occupational health reasons and from an environmental point of view in terms of sensitive receptors including National Grid sub-station, Didcot B power station, local industrial/ commercial and residential properties which may be sensitive to dust. 204. Dust will include both fine and light fraction particles, the lighter fraction remaining airborne for longer and potentially travelling further afield. 205. In order to manage dust formation at source and manage dust created, the demolition techniques shall be used as far as possible to minimise the dust, with the exception of explosive demolition where this is not possible.

6.2.14 Dust Control Measures 206. The following management methods shall be employed: 207. General demolition:

• Air monitoring will be undertaken and the results evaluated and recorded throughout the demolition period. • Dust suppression techniques will be used to control the formation of dust and control fumes and sparks from the hot works. Due to the nature of the demolition, with many structures being of steel construction, the amount of dust and particles created is expected to be low. • Vehicles and machinery are to be turned off when not in use, be well maintained and have clean exhaust emissions. • Damping down with a fine mist the areas to be demolished, where required • Damping materials which are being or are awaiting processing, whilst controlling the level of water used in terms of silt formation and run off which could cause an environmental issue and whilst the use of resources is managed to prevent over use of water resources (drains are protected with G3 filter / bung or similar) • Roadways are maintained to minimise the formation of dust • Control of traffic movement including speed to prevent / minimise the formation of dust • Use of road sweeper where necessary

208. Additional controls for high reach equipment: • On board dust suppression - pumped water is pressured along the length of a water pipe which runs the length of the machines high reach arm. This water is then atomized over the attachment and the working area of the concrete cracking. • Additional dust suppression at height – Water is pumped from a holding tank that is filled over night from a metered main. The hose that is used for the water is tied and secured to a ‘cherry picker’ spraying water at basket level. The hose head is directed in the working area of the demolition work adjusted to suit the height of the demolition works. This ensures that the concrete and brickwork is damped down as it falls from the area of the attachment. • Additional dust suppression at ground level – A Dust Boss will be used which atomizes the water by placing it within a propeller type blower. The blades to the propeller spilt the water into minute particles whilst at the same time blowing the fine mist over the base of the demolition area. • Site control wind speed monitoring – If high wind speed present’s an environmental concern. Where possible the operation will cease until such time that the wind speed has reduced to an acceptable level.

209. Additional Controls for Explosive demolition:

• Take account of the direction the structures will fall and protect any sensitive receptors, this may include inlets to air conditioning units; drains etc which may need prior protection with G3 or similar filters • Washing / cleaning of areas affected by dust following the demolition (where required) which may include buildings and vehicles in addition to roadways.

6.2.15 Dust monitoring 210. Depositional dust monitoring will be undertaken throughout the phases of work and will take into consideration which demolition activities are taking place to ensure that they are included in the monitoring regime. Typically more than one activity will be included in the monitoring period. The depositional dust monitoring will not be undertaken during the early works or for background readings. 211. The dust monitoring will be undertaken by independent external consultants on behalf of the Demolition Contractor following the guidelines in the Beaman & Kingsbury Method (Beaman & Kingsbury - Assessment of Nuisance from Deposited Particulates Using a Simple and Inexpensive Measuring System - in Clean Air, Vol 11 No 2 pp77-81, 1981) which uses a simple method of assessing the level of deposited dust or other articles on a vertically positioned cylinder with a sticky pad attached to its outer surface. The level of deposition is measured using a calibrated light meter and is assessed against calibrated scale of deposition. The level of deposition indicates the likelihood of complaint being received and can be compared between locations/ against time. Due to the vertical position of the cylinder it can be assessed against points of the compass to indicate from which direction the dust has been blown. The final monitoring locations, methodologies and frequencies for dust monitoring will be agreed with the LPA. 212. The positions for depositional dust monitoring will change as the activities on Site vary but will be undertaken at positions which are in the ‘free field’ at a height of approx 1.3m from the ground surface. The positions chosen will typically be located close to the Site boundary with sensitive receptors and / or within the demolition Site boundary, surrounding active zones of demolition work. The frequency of dust monitoring will be dependent upon the length of the programmed work activities within one or more zone to obtain the worst case scenario for the dust levels. 213. Dust monitoring will be undertaken over a one week period to prevent loss due to precipitation or over-soiling of the pad.

6.3 Land Contamination 214. Didcot A power station operated under the terms of an Environmental Permit (YP3030LR) issued by the Environment Agency (EA) to ensure it did not cause pollution of the air, water or land. This Permit remains in force and only when the

EA are satisfied the Site no longer presents a pollution hazard may the Permit be surrendered 215. Since withdrawing from service in March 2013 the power station has been through a period of decommissioning to make it safe and remove as many potentially polluting materials as possible. All bulk chemicals and fuel stocks have been removed from Site during the decommissioning period. As a result the Didcot A site is no longer classed as a lower tier site under COMAH. 216. The information presented below provides a summary of the ground conditions at the Didcot A power station Site, and identifies previous uses of the Site and potential contamination sources.

6.3.1 Site history

6.3.1.1 On-Site Land Use 217. A review of historical maps provides the following information on the development of the Site. 1883 -1913 The Site at one time formed part of an orchard associated with the nearby Durnell's Farm in the early 1900's. The railway ran to the south. 1915 – 1932 The Site and surrounding area was developed as a Central Ordnance Depot. Swimming baths and a recreation ground are labelled to the north and east, but Ordnance Survey maps of 1932 have the southern part of the Site is blanked out. 1933 – 1964 The Site operated as the MoD Central Ordnance depot, with substantial number of rail connected workshops across the southern half of the Site. There were a number of smaller buildings across the central and eastern area, identified as Guards Depot Camp, Officers Canteen, Swimming Bath and yard areas. There is a larger workshop building in the north west but the northern half of Site, although still within the depot boundary, is largely unoccupied by depot buildings. The old channel of Moor Ditch crosses the Site. Recreation land lies to north of the ditch within the Site boundary. 1964 - 1970 Construction of Didcot A Power Station. The southern area of the Site was used as a contractor’s compound and construction area. 1975 – date The Site was occupied by Didcot A power station. The northern part of the Site houses the main operational buildings, including the Open Cycle Gas Turbines. The power station developed as per existing layout with Moor Ditch realigned. An effluent treatment plant is shown on the maps from 1986 to 2006, replaced by a lagoon system on southern boundary of coal yard. The area of the effluent treatment plant is now occupied by ash storage mounds which had been relocated from the land now occupied by Didcot B power station. The southern part of the Site was an area to store both coal and (PFA). During power station construction material was imported to correct the Site contours and much of the Site comprises made ground. 1990 - date The western part of the Site was prepared for the development of Didcot B Combined Cycle Gas Turbine power station. This included the emptying and removal of three above ground tanks on the north eastern area of the Site. At this time, an intrusive investigation was carried out at the Site. Construction work on Didcot B subsequently commenced. Table 15. Historical overview of land use (on-site)

6.3.1.2 Surrounding Land Use 218. In terms of historic contaminative uses, the following summarises the development of surrounding land: 1883 – date Great Western railway line located 120m south of the Site 1932 - 1975 Gravel pits are shown as present 70m north-west and 400m west north-west of the Site 1970s- date Milton trading estate was built on land adjacent to the western boundary of the Site in the late 1970's occupying many of the former ordnance depot buildings. The barracks to the south east had been replaced by residential properties. In addition, a large landfill was present 220m north east of the Site, extending west. Southmead Industrial Park had been developed 750m east south east of the Site. Table 16. Historical overview of land use (surrounding area)

6.3.1.3 Potential for soil or water contamination 219. Potential historic contamination of the Site might have resulted from its use as an MoD storage depot, including the extensive railway sidings which serviced the depot. 220. The Site’s use as a power station may have resulted in potential contamination from: • coal and ash storage • lubricating oil storage • operational chemical storage • site drainage system • railway sidings • fuel tanks and coal plant vehicles • deposition of road sweepings and rubble • contractors area

221. Areas of interest for potential soil and groundwater contamination therefore include the coal stock handling area, ash storage areas, reserve coal stock area, ash conditioning site, major chemical and fuel storage areas, National Grid sub-station (although this is not in RWE’s ownership) and equipment storage at Didcot A. 222. Off-site land uses with the potential to cause soil and groundwater contamination at the Site by on-Site migration include • landfill Sites to the north of the Site • Southmead Industrial Estate • Milton Trading Estate • Railway infrastructure.

6.3.2 Site geology 223. BGS data indicate the geological sequence beneath the Site is as follows: 1. The ground contours indicate that the surface was modified during power station construction and contains areas of made ground and landscaped ground of uncertain thickness and composition across the Site. Depth of these deposits is believed to be up to 6 m. 2. Beneath the surface, the northern part of the Site is underlain mainly by river terrace deposits of both the Summertown-Radley member (second terrace of the River Thames) and the Northmoor member (first terrace of the River Thames). These deposits comprise sandy gravel, and include thin sand or clayey silt layers. Their thickness is up to 5m, but is very variable. Running east-west across the centre of the Site are a band of river alluvium believed to be about 2 m thick, comprising slightly gravely clayey silt or silty clay and a band of Gault. The southern extremity of the Site is underlain by Head, a grey stony sandy clayey silt, again with variable thickness, but typically about 2m thick. 3. The entire Site is underlain at rockhead (typically 0 – 5m below the surface) by the Gault formation, comprising pale to dark-grey or blue-grey mudstone which is at least 40 m thick. The Gault Clay is further underlain by Lower Greensand (sand, gravel and clay of up to 60m in thickness), Kimmeridge Clay (shale and clay up to 90m in thicknesses of up to 30m) and Oxford Clay (predominantly clay with thicknesses ranging from 120 - 175m). 224. The Environment Agency Thames Region has classified both the Alluvium and River Terrace Gravels underlying the Site as minor aquifers whilst the Gault Clay further underlying the Site has been classified as a non-aquifer. Given the depth and impermeable nature of the clay, any groundwater present in the overlying permeable deposits (i.e. alluvium, river terrace gravels and fill material) constitutes a distinct aquifer. 225. The Lower Greensand (comprising sands, gravels and clays) and the Corralian Beds (comprising sands, silts, clays and limestone) are also classified as minor aquifers whilst the Kimmeridge Clay and Oxford Clay have been classified as non-aquifers. Any groundwater present within the Lower Greensand and Corralian Beds will likely be confined as a result of the impermeability of the overlying and underlying strata. 226. There is likely to be a shallow water table present beneath the Site (<5m bgl) which rests within the fill and the Alluvium and River Terrace Gravel drift deposits. The shallow groundwater is likely to be in hydraulic continuity with nearby surface water bodies, for example Moor Ditch, and is likely to flow in a northerly direction towards the River Thames, located 2.5km north of the Site. 227. The relative permeability of the underlying drift geology means mobile contaminants present on the Site could potentially migrate laterally off-Site. However, the deeper Gault Clay is of low permeability and would act to retard the vertical migration of such contaminants entering the deeper water bearing strata (Lower Greensand).

6.3.3 Storage and control of potentially polluting materials on site during operation 228. Didcot A power station was built by the former Central Electricity Generating Board. The Site was constructed to very high standards, and all potentially polluting materials were stored in bunded areas. The Site incorporates large areas of hardstanding. The operation of the Site has been to a similar high standard with no significant instances of accidental releases or pollution recorded. The Site operated a formal system of environmental management accredited to ISO 14001. All activities involving potentially polluting materials were undertaken by trained personnel using agreed procedures to minimise the risk of pollution incidents. The integrity of bunds and other containment measures was maintained through the life of the Site.

6.3.4 Potentially polluting materials on site

6.3.4.1 Liquids 229. The main potentially polluting liquids which were used and stored on the Site were: 230. Heavy fuel oil; Gas oil; Paraffin; Lubricating oils; Caustic soda; Sulphuric acid; Hydrazine; Ammonia; Sodium hypochlorite; Sulphur; Methanol (discontinued 1998); Waste water; Waste oil. 231. All bulk tanks were above ground, maintained in sound condition, and free of evidence of leakage. 232. Tank and bund integrity was assured by regular inspections by operations staff, backed up by scheduled detailed examination carried out in accordance with the company’s technical procedures, based upon their contents, risk of corrosion etc. Some smaller quantities of materials were stored in manufacturer supplied containers such as steel drums or Intermediate Bulk Containers (IBCs). 233. All tanks, drums and IBCs containing potentially polluting materials and all oil- containing transformers were enclosed in sealed concrete or masonry bunds. Rainwater and any leakage were removed by gully sucker on a routine basis by station staff. Material removed was dealt with as required by its condition, with any potentially oil contaminated water being passed through separators before discharge. 234. Waste water from the Site was dealt with in lagoons and oil separators in the drainage system. The main station lagoons received the drainage run-off from the Site road drains, drainage lagoons and various separators on the Site. The construction of the sides and bases of these lagoons is pre-cast concrete slabs resting on stabilised ash. There is no evidence of subsidence, and the base shape profile remains sound.

6.3.4.2 Solids 235. The main solids which were used and stored on the Site were: 236. Coal; Pulverised fuel ash (PFA); General solid waste; Plant and maintenance waste; Scrap metal; Oil contaminated waste.

237. The main coal stock was located in the southern part of the Site. The majority of the coal stock was underlain by a reinforced concrete slab. Where the slab was absent at the western end of the coal yard and to the east including around the cooling towers the ground conditions comprise up to 1 metre of made ground over a geotextile layer and compacted concrete rubble. All wastes were segregated and stored in skips located on areas of hard standing. Licensed contractors were employed to remove them from Site.

6.3.5 Ground contamination studies

6.3.5.1 2008/9 investigation 238. Prior to the construction of Didcot A station in the 1960s no contamination investigations were undertaken. A report was prepared by Jacobs in 2008/2009 when they were commissioned to review the options for a proposed Didcot C Power Station, with part of the new power station’s footprint on the coal stock yard. Ten trial pits excavated to 4.5m and three boreholes to 10m were drilled on the coal stockyard. The soil samples from these came back with relatively low levels of contamination. No metals were detected above the commercial/industrial Soil Guideline Values (SGVs) and no asbestos was identified. Slightly elevated Total Petroleum Hydrocarbons was recorded in one sample to the south of the coal stockyard but none detected in groundwater samples. Slightly elevated concentration of Benzo(a)pyrene was identified in soil samples in two trial pits and boron and selenium concentrations in groundwater were detected above drinking water standard but below freshwater EQS for boron (there is no EQS for selenium but concentrations only slightly exceeded DWS).

6.3.5.2 2013 investigation 239. The main power station site was subject to a pre-demolition intrusive investigation in 2013 by ESG. 27 boreholes were drilled down to a maximum of 6 metres below ground level. Ground conditions were recorded and groundwater monitoring and sampling was undertaken. 11 hand dug pits were also attempted, restricted to a maximum of 1 metre due to concrete obstructions. The borehole locations were chosen to be in areas where, due to the site operations, there was a possibility of contamination. The following samples were taken and analysed: 240. Metals suite – arsenic, boron, cadmium, chromium, cobalt, copper, mercury, manganese, molybdenum, nickel, lead, antimony, selenium, tin, thallium, uranium, vanadium, zinc 241. Hydrocarbon suite – BTEX (benzene, toluene, ethylbenzene and xylenes) plus MTBE, PAHs by GCMS, 16 priority pollutant PAHs, TPH by GCFID (C8 to C40) with aliphatic and aromatic class separation and carbon banding 242. Core suite – asbestos screening and identification, pH 243. No unexploded ordnance survey has been undertaken on the Site, but there have been no recorded encounters of any such materials during the construction of Didcot A or during the investigations or works undertaken for the construction of Didcot B.

244. The summarised results of the investigation works are: • No significantly elevated concentrations of metals or BTEX were recorded, with, where applicable, levels well below the commercial soil guideline values and generally below those for residential use. • Elevated hydrocarbons were found at shallow depth in close proximity to some above ground tanks (Mobil Oil Storage Tanks (up to 1595 mg/kg) and vehicle fuel tanks near the coal stockyard (up to 1182 mg/kg), adjacent to the rail loop (471 mg/kg) and also in the made ground below the coal stockyard (up to 605mg/kg). The hydrocarbons were predominantly in the C21-C25 range. The hydrocarbons identified in the made ground below the coal stockyard are possibly as a result of the former MoD depot use as the borehole was situated on the historic rail sidings. • No asbestos has been detected. • pH range 8.6 to 9.3 (except BH26, 0.3m where pH 11.9 recorded) • A groundwater sample from the made ground below the coal stockyard recorded concentrations above Drinking Water Standards for arsenic, manganese, nickel, selenium and benzo(a)pyrene. There are a couple of other occurrences of concentrations slightly above Drinking Water Standards of manganese, selenium and benzo(a)pyrene. 245. The original line of Moor Ditch was considered a possible pathway for contaminant migration, as part of the ESG investigation a borehole was drilled in proximity of the old channel. There is no evidence that the channel was infilled with demolition debris from the former MoD depot and there is no evidence of contamination, there was also no evidence of groundwater flow along the old channel.

6.3.6 Environmental Permit application 246. As part of the Permit re-application process in 2007, RWE undertook a review of the pollution potential of the Site. The Environment Agency was provided with a Site Condition Report as part of the application and subsequently a Site Protection and Monitoring Programme. These provided the EA with details of the environmental management systems and operational procedures that were in place. The EA did not require any intrusive site investigation work and the Permit was issued.

6.3.7 Decommissioning process for potentially contaminating materials 247. As part of the decommissioning process the majority of liquids have been drained from the plant. Boiler dust and PFA have been removed and the coal stock has been cleared. 248. The site records show that there have been no significant incidents of pollution on the Site, nor any long term leakage of any stored materials. With such a large industrial site, it is inevitable that there may be some isolated occurrences of limited pollution. These will be dealt with to the satisfaction of the EA during the demolition process.

249. Preventing pollution from residual material remaining in plant items will be a key requirement of the demolition process. Surrender of the Environmental Permit may only occur when the EA are satisfied that the Site is returned to its condition at the time of Permit issue.

6.3.8 Control Measures during Demolition 250. There are no below ground works proposed as part of the demolition activities at Didcot A. However, in the event of contamination being identified the works shall be paused whilst advice is sought and samples will be taken if required. In the event of contamination being encountered site specific risk assessment and associated procedures for working with poor ground conditions will be developed. 251. COSHH assessments shall be undertaken in the event of contamination being encountered and methods for managing contaminated material developed accordingly with associated risk assessments. It is anticipated that minimal direct handling of contaminated materials will be required. Due to the previous contaminated land assessments which have taken place on the Site the location and type of contamination which could be encountered are well understood. 252. Throughout the duration of the demolition works due care and attention will be taken in ensuring all measures are taken to prevent the spillage of hazardous substances into the environment. All substances stored on the Site (including those brought onto the Site by the demolition contractor and those located on Site as a result of the previous site operation) will be bunded or contained as per COSHH Regulations. An emergency procedure will be made known to all site personnel and sub-contractors and shall include the provision of a fully stocked spill kit including the required storage and disposal of used absorbent materials. All existing substances will be identified and the necessary action taken to contain these during the demolition process. 253. The demolition contractor will adopt a four tiered system of approach to dealing with the removal of oils or lubricants that remain within pipework or machinery on site: 254. Stage One – Flush Pipework 255. The first stage will be to try and remove the oil under controlled conditions with specialist contractors. A contractor would contain & remove the oil from plant, machinery or pipework with trained & competent operatives by approved techniques. This approach may prove difficult due to the extent and length of pipework, with either flushing or cleaning techniques. 256. Stage Two – Contamination Area 257. This would involve the cutting of pipework or plant and removing it to a “contamination area” where it can then be dealt with. The contamination area will be sheeted & bunded off to prevent uncontrolled leaks, and the oil would be removed from the equipment through gravity and the equipment removed from the area once classed as clean. The oils will then be removed from the contamination area by trained & competent operatives using approved techniques. 258. Stage Three – Local Spill

259. This stage would deal with an un-controlled release of oils or lubricants onto the ground. The containment procedure would be to deal with the immediate incident with absorption mats to contain, limit the spread of oil and to clean the area. Any spillage or un-controlled release of oil within the Turbine Hall will be dealt with separately. The first operation will be to contain the oil so it does not pollute any drains or water course and to limit the spread of the oil. 260. Dedicated spill kits will be positioned within each working area and will contain the follow items of equipment: • Absorption Socks • Absorption Mats • Drain blocker/bungs • Disposal Bags 261. A ring of socks will be placed around the perimeter of the oil and a series of absorption mats will be placed over the spillage to absorb as much of the oil as possible. The mats or granules will be allowed to soak for a short period of time and then will be removed with operatives wearing the appropriate P.P.E. The mats will be placed into the Disposal bags, sealed and placed into a Hazardous waste bin. If during the course of the works a spillage was to occur, then the Site Supervisor would compile a report of the incident and submit to RWE. 262. Stage Four – Final Containment 263. The final stage for containment would be if there was a release of oils into the existing drainage system, this would be retained within the existing catch pits. Once within the catch pits the oils would be separated from the water and the oils cleared from the top with oil mops and suitably disposed of through a licenced contractor. Water could then be released into the water lagoon before entering the water course 264. Mercury Switches 265. Due to the age of the station it has been identified that there is mercury contained within the switches of the Turbine Hall. Prior to any hard demolition works the switches containing mercury will be physically identified ready for removal from Site. A specialist contractor will be employed to review and determine the approved means of removal. A safe system of work will be developed, compiled and submitted for approval, and this method & sequence will be covered under a separate method statement. A mercury spill kit will be present on site and will be held with the sub-contractor whilst removing the mercury containing devices including switches and indicators. 266. All waste mercury and mercury spill kit will be disposed of off-site and be accompanied by a Consignment Note. 267. All vehicles used on the Site will be maintained and inspected on a regular basis to ensure there are no leakages or emissions of non-standard materials into the environment. Any necessary repairs shall be undertaken in a controlled manner in a location so as to prevent contamination from entering the ground or watercourses.

268. Visual inspections shall be undertaken of the stream and water treatment plant on a regular basis to determine any potential contamination as a result of the works. The inspections shall be recorded. Any noticeable contamination will be immediately reported to the Site Supervisor – to the Project Manager and to RWE’s Environmental Chemist. It must also be immediately reported to the HSEQ Department. 269. The demolition contractor will identify and seal any drains as necessary to undertake the demolition so as to prevent contamination by rubble, waste, silt or other contamination. As appropriate, drains may be sealed or protected typically using sandbags. The type of filters (G3) will not protect against oils etc. 270. Waste will be handled in accordance with the demolition contractors Environmental Management System (EMS) procedures (see Environmental Management Plan, Appendix 16). All waste materials removed from the Site will be disposed of at suitably licensed landfill sites by registered waste carriers. A waste transfer / consignment ticket system will be maintained to record the designation and destination of each load of waste material from the works. 271. All materials that are deemed hazardous will have an MSDS and COSHH assessment associated with them which will detail the risks of each material, first aid action and fire precautions and shall also include proposals for controlling their use / contact, storage and disposal. Where possible, the introduction and use of hazardous substances shall be eliminated or substituted for less hazardous materials. 272. All fuel will be stored on the Site in a double skinned bunded tank. All storage and refuelling will take place away from sensitive receptors (surface and foul drains) and be undertaken on hard standing areas. Oils and lubricants brought to the Site will be stored either in the back of the bunded tank or on a drip tray inside a locked metal store. Spill kits will be positioned around the Site at designated refuelling points. 273. No bulk contaminations are considered present on the Site following removal prior to the commencement of demolition. The former bulk storage materials included heavy fuel oil, oil and sulphuric acid. It is anticipated that whilst the former bulk storage tanks and associated pipework has been emptied, residual materials including material within bunds are likely to be encountered. The bund structures are also likely to be contaminated over years of use. Additionally, various 205 litre and smaller containers of oil etc are present on the Site and require controlled storage and disposal. There is associated contamination with bulk and smaller containment of materials, particularly of brick and concrete which will require segregation in terms of prevent direct handling and for waste disposal purposes. 274. By implementing the control measures detailed above, and ensuring that all employees follow the required procedures for dealing with potentially contaminated materials, the potential impact on the surrounding environment will be minimised.

6.4 Ecology

6.4.1 Baseline Ecology

6.4.1.1 Introduction 275. There is a significant amount of existing ecological survey data for the Didcot A Site and this has been used to summarise the baseline ecological conditions. This section provides - an overview of the methodologies employed in the baseline surveys; - identification , description and evaluation of the existing (baseline) ecological resource within the study site; - identification of the potential impacts upon the ecological resource within the likely zone of influence of the demolition works and related activities; - proposed mitigation and enhancement works

276. Further detailed information can be found in Appendix 17.

6.4.1.2 Relevant Legislation 277. Conservation of Habitats and Species Regulations 2010 (as amended). The Conservation Regulations enact both EC Directive 92/43/EEC on the Conservation of Natural Habitats and of Wild Fauna and Flora (the Habitats Directive) and EC Directive 2009/147/EC on the Conservation of Wild Birds (the Birds Directive). Specifically, they provide for the protection of European Sites - Special Areas of Conservation (SAC) and Special Protection Areas (SPA) – and also those European Protected Species (as listed in the Annexes to the Habitats Directive) that occur naturally in the United Kingdom. 278. Wildlife and Countryside Act (WCA) (1981) (as amended). The WCA remains one of the principal pieces of legislation relating to wildlife in the United Kingdom (UK). Contained within it are lists of species of flora and fauna subject to statutory protection, with the Act detailing the level of protection attributed to each, which in some instances extends to the habitats or structures they use or in which they are found. The WCA is also the primary piece of legislation relating to the designation and protection of Sites of Special Scientific Interest (SSSIs). 279. Protection of Badgers Act (1992). This Act, as the title suggests, affords a high level of protection to both badgers and their setts, with the intention of combating persecution. The legislation was introduced primarily for reasons of animal welfare as opposed to any concern over the conservation status of what is one of the UK’s more common larger mammals. 280. Countryside and Rights of Way (CRoW) Act (2000). 281. The CRoW Act strengthens the provisions of the WCA in several key areas, in particular: - in respect of SSSI protection; and - in the inclusion of ‘reckless’ in addition to the intentional nature of offences listed within parts of the WCA 1981.

282. The CRoW Act also imposed for the first time a ‘statutory duty’ on Government bodies to ‘have regard’ to the conservation of biodiversity in the exercise of their functions, a duty later reinforced and extended to all public bodies by the Natural Environment and Rural Communities (NERC) Act 2006. This provided a statutory basis for the Biodiversity Action Plan (BAP) system put in place by the UK Government in response to its commitments as a signatory of the 1992 Convention on Biological Diversity (the ‘Rio Treaty’). The UKBAP, first published in 1994 but subject to periodic review, identifies species and habitats considered to be important to the UK biodiversity resource and/or threatened in the UK context. These now correspond with lists of species and habitats of ‘Principal Importance’ drawn up by the government in response to the obligations levied by the CRoW and NERC Acts. 283. Natural Environment and Rural Communities Act (NERC) (2006). The NERC Act reinforces the requirements originally set down in the CRoW Act on the Government (and extending to all public bodies), to have regard to biodiversity and to identify and take steps to conserve species and habitats of ‘principal importance’. This requirement has been addressed through the drawing up and maintenance of lists of species and habitats which are considered of ‘principal importance’ to biodiversity in the UK. These lists equate to the priority species and habitats under the UKBAP. 284. The National Planning Policy Framework. The National Planning Policy Framework (NPPF) sets out current applicable central Government policy on planning, including how national policy on nature conservation should be delivered through the planning system. Together with its supporting Circular 06/2005, it details how the protection of statutory and non-statutory sites is to be pursued through the forward planning and development control frameworks and also sets out how local authorities are expected to approach decisions affecting protected species. The NPPF contains a core aim to maintain, and enhance, restore or add to biodiversity and geological conservation interests in planning policies and planning decisions. There is also the aim within NPPF that there should be no net loss of biodiversity as a consequence of development projects, and that net gain should be sought and delivered wherever possible. 285. The regional and local planning documents, and the relevant specific policies, are presented in Appendix 17.

6.4.1.3 Baseline Data Collection 286. The Site encompasses the entirety of the ‘A’ Station demolition site, which was the subject of a programme of ecological surveys between November 2007 and December 2008, with further update surveys undertaken throughout 2011. Survey information is also available for the ‘wider study area’ which encompasses the entirety of RWE npower’s landholdings at Didcot. The ecological character of the wider study area has been used to place the ecological character of the demolition site in the local context. 287. The survey methodologies employed for each of the species/habitats present on the Site are presented in Appendix 17.

6.4.1.4 Baseline Description

General Ecological Context 288. The Site falls within Natural Area 63; Thames and Avon Vales (English Nature undated). Defining characteristics of this Natural Area include relatively flat river valley land on heavy clays, with key nature conservation features including localised significant survivals of neutral grassland, damp grassland of value to wintering birds, woodlands and flooded gravel pits as well as the major river systems. 289. The soils of the wider study area are mapped predominantly as loamy argillic and somewhat calcareous brown earths of the Sutton 1 Association, with calcareous alluvial gley soils of the Fladbury 1 Association occurring in the southern part, south of the Moor Ditch. The overall site topography is broadly level. 290. No Sites of Special Scientific Interest (SSSI), Special Protection Areas (SPA’s) or Special Areas of Conservation (SAC) lie within the proposed demolition site and there are none in the immediate surrounding area. The closest SSSI is Culham Brake which lies approximately 5.1km to the north of the Site. The nearest SAC is Little Wittenham, which lies 6.3km to the north east of the study area. Little Wittenham is designated as a SAC for its population of great crested newts. There are no SPA’s within 15km of the proposed development site. There are no non-statutory designated sites within the demolition site, or wider study area; the closest such site occurs 2.5km away, Hulgrove Farm Meadow (Local Wildlife Site).

Existing Species Records 291. Records of noteworthy species provided by Thames Valley Environmental Records Centre (TVERC) in 2011, i.e. those included on the various Schedules of the WCA, listed as of Principal Importance further to Section 41 of the NERC Act 2006, or listed in the schedules to the Habitats Regulations 2010, and recorded within 1km of the demolition site since 2000, are presented in Table 17.

Species Conservation Status A mouse eared (Myotis) bat species Sch. 5 – all Parts EPS Black Redstart Sch. 1 Common Frog Sch. 5 Parts 5(a) and (b) Galingale Scarce (VP) Great Crested Newt Sch. 5 – all Parts EPS/SPI/BAP Hobby Sch. 1 Kingfisher Sch. 1/Annex 1 Little Egret Annex 1 Little Ringed Plover Sch. 1 Peregrine Falcon Sch. 1/Annex 1 Pipistrelle bat species Sch. 5 – all Parts EPS Red Kite Sch. 1/Annex 1 Smoot Newt Sch. 5 Parts 5(a) and (b) Toothed Medick Scarce (VP) West European Hedgehog BAP/SPI KEY: Sch.5 – Schedule 5 of WCA; Sch.1 – Schedule 1 WCA; EPS – European Protected Species; SPI – Species of Principal Importance; BAP – Biodiversity Action Plan; Annex 1 of Birds Directive. Table 17.Noteworthy Species recorded within 1km of the demolition site since 2000

Habitats and vegetation 292. A total of 20 distinct habitat types have been identified from within the proposed demolition site. The location and extent of each habitat is depicted on Figure 2, Appendix 17. 293. A large proportion of the habitats within the Site are man-made and of relatively recent origin, so are of limited intrinsic ecological value. However, in the areas where more established grassland or other vegetation occurs, a relatively large proportion has some features of interest. 294. This is principally due either to the influence of PFA, or (very locally) coal dust, on the chemical and nutrient status of the substrate, or, in some cases is due to the habitats having been developed and managed relatively non-intensively (e.g. by annual mowing) for a period of several decades. Such continuity of management has created a locus of non-agricultural grassland against a backdrop where most such habitats in the locality have been subject to some form of agricultural ‘improvement’ or, conversely, neglect. 295. The relatively diverse suite of conditions created by the juxtaposition of highly artificial habitats with those reflective of a continued period of consistent management, and those that have developed through neglect is reflected in a relatively high species-total for wider study area. In total, well over 300 plant species were recorded form a total of 20 distinct habitat types within the confines of the wider study area, and this is very unlikely to be a comprehensive list. 296. Within the demolition site itself, the plant species of more note recorded include the following:

• Those associated with and indicative of unimproved mesotrophic grasslands, here occurring in semi-natural assemblages on neutral to slightly calcareous clay. Prominent amongst these are forbs such as greater knapweed, agrimony, fairy flax, yellow-wort, hoary plantain, bee orchid and pyramidal orchid. • Those associated with the particular conditions created on PFA substrates – including narrow-leaved bird’s-foot trefoil and annual beard grass, both being species more normally associated with coastal regions. • Species typical of disturbed ground, including in particular corn parsley and common cudweed. 297. Several of the plant species recorded are rare in the Oxfordshire context, and a few are uncommon nationally. The first of these is common cudweed, recorded from eight 10km squares in Oxfordshire during the period 1987 through to 1999 (Preston et al. 2000), was found at a disturbed path edge in the south-eastern part of the demolition site. This species is declining nationally, and was given the status ‘Near Threatened’ by the JNCC in 2005 (Cheffings and Farrell 2005). 298. Dittander, which is normally associated with creeks and ditches near salt marshes, was recorded within a tall herb and sedge community adjoining one of the northern cooling towers of A-station. This perennial herb is expanding its range in the UK, being now found in a variety of habitats such as waste ground and railway sidings. It is currently known from only three 10km squares in Oxfordshire and is therefore locally rare. Two other locally rare species of Lepidium were also recorded in disturbed ground habitats on the Site: Smith’s pepperwort and narrow-leaved pepperwort. 299. Other species recorded on the demolition site that qualify as locally rare include naturalised species such as tall rocket and annual beard grass. Again these habitats were associated with disturbed ground on the demolition site, the latter particularly in areas influenced by PFA.

Invertebrates 300. Approximately a quarter of the invertebrate species recorded in the three compartments across the wider site targeted for survey have an elevated conservation significance, suggesting that the invertebrate assemblage of the wider study area as a whole is of significant value at least in the Oxfordshire context. As expected, given experience of other PFA sites both locally and nationally, the greater proportion of this interest appears to be associated with aculeate Hymenoptera, for which the presence of PFA in conjunction with flower-rich, successional stage habitats, provides a particular suite of conditions of high value for nectaring and foraging. Significant areas of habitat likely to be of value to this invertebrate assemblage fall within the southern part of the demolition site. Of the total invertebrate species found in the targeted sample area at the southern edge of the demolition site, 22% have an elevated conservation status, including one former Red Data Book species (the bee wolf Philanthustraingulum) and four Nationally Scarce species including the bee Lasioglossumpauxillum.

301. In consideration of the particular requirements of the species of conservation interest found in the wider study area, a significant degree of inter-dependence between the ‘hotspots’ of the sampled compartments is likely. Consequently, areas of successional habitat and/or PFA within the demolition site may contribute to the wider site’s overall interest.

Great Crested Newts 302. The various water bodies surveyed within the wider study area are assessed as supporting a ‘medium’ population of great crested newts with a maximum count across the Site of 33. Due to the proximity of the water bodies to one another, it is likely that this is acting as a single meta-population, in conjunction with adjoining areas including the Sutton Courtenay Environmental Education Centre. Although the UK population of great crested newts is important in a European context, they are relatively widespread in a local context. No great crested newts have been recorded within the demolition site itself, however, they have been recorded within 100m of the Site boundary. The northernmost part of the demolition site provides both suitable foraging habitat for this European Protected Species and is connected to areas known to support them by suitable habitat links, so there is a likelihood that small numbers of the species range into this area during their terrestrial phase.

Birds 303. The bird species found during the five months of wintering bird surveys of the wider study area make up an assemblage which, with certain exceptions, is generally similar to that which may be found within any urban fringe setting. The smaller size and relative paucity of vegetation within the demolition site further suppresses the breeding assemblage there, and only 17 species are associated with this area. Given the demolition site’s size and location the number of species recorded and their relative abundance are considered to be lower than may otherwise be expected. Of more elevated conservation importance is the presence of peregrine Falco peregrinus; a species most likely to be present due to the Site containing suitable elevated nesting sites, as well as a resident population of feral pigeons. Overall the demolition site forms part of wider area with a breeding and wintering bird assemblage assessed as being of Local value, with exception of the presence of a long-eared owl winter roost, which is a feature of County importance but is outside the demolition site.

Bats 304. While some potential roost sites have been identified within the demolition site; no bat roosts have been confirmed to date. Activity surveys of the demolition found common pipistrelle to be by far the most frequently detected bat species, with soprano pipistrelle detected to a much lesser extent. Soprano pipistrelleis a UK BAP species and is a Species of Principal Importance (SPI) and is Britain’s second most common bat species. Nathusius’ pipistrelle was recorded much less frequently than the other two pipistrelle species, with all the records occurring in August 2011. This species is still considered rare in the UK, although records have significantly increased in recent years, and there are a scattering of recent records in central and southern Oxfordshire, many associated with the Thames. Noctule, a national BAP

species and SPI, was the only larger bat species to be recorded at the Site. The only record of a Myotis species from the demolition site (in 2009) has been identified to genus level only. Overall, bat activity within the demolition site was low; albeit with some sites displaying slightly higher bat usage. The presence of Nathusius’ pipistrelle raises the interest of the wider study site in terms of the site’s bat value, however the nature of the habitats within the demolition site is such that relatively limited opportunities for roosting and foraging are present. Therefore, the demolition site’s value to bats has been evaluated to be measurable at local level at best.

Water Voles 305. Water voles have undergone a dramatic decline in the UK since the 1950’s; so much so that changes were made to the legislation in 1998 and 2007 to raise their level of protection. However, due to ongoing work by conservation organisations, the species distribution is beginning to improve. 306. Water voles were found to be present, at apparent low density, along some sections of the Moor Ditch in 2008, but no recent signs were detected during the 2011 survey.

Badgers 307. A main badger sett was identified in the 2008 studies to be present on land within the wider study area (but outside the demolition site) to the north-west. The importance of the wider study site to badgers, which remain a common and widespread species, can be assessed as of value at local (i.e. Parish) level. However, no evidence of badger use was found within the demolition site itself, so the demolition site is likely to have negligible value for this species.

6.4.2 Predicted Impacts and Mitigation 308. The following information presents the current understanding of the predicted impacts and mitigation requirements associated with the demolition project. This has been updated and revised since completion of the Demolition Ecology Assessment (Appendix 17).

6.4.2.1 Statutory and non-statutory designated sites 309. There would be no direct negative impact upon any statutory or non-statutory designated nature conservation site. A certain amount of noise and dust may be created as a result of normal demolition activities, but due to the distances involved this would not impact upon any statutory or non-statutory sites. In fact, the decommissioning process may result in an indirect, long term, positive impact upon the wider area, and hence nearby statutory and non-statutory designated sites, through lowering of emissions into the local atmosphere. As no significant negative impacts are predicted upon any European designated site, the need for a Habitats Regulation Assessment is not deemed necessary.

6.4.2.2 Habitats – buildings 310. With the exception of providing limited bird breeding and possible bat roosting opportunities, the buildings themselves have negligible ecological value, so their removal would result in a negligible direct impact upon the ecological resource, both within the Site and in the surrounding area.

6.4.2.3 Habitats – vegetation 311. Much of the vegetation within the demolition site is species-poor plantation or sown grassland with a high degree of artificiality and limited species interest, but there are areas with unusual floristic assemblages as well as the occasional uncommon species. The assemblages have been created, in the main, as a result of long term persistent management of manmade habitats, although a very few areas may represent ‘fossilised’ fragments of historical landcover. Of particular note are areas of unimproved, mesotrophic grassland and those grasslands which have developed on a predominantly PFA based soil profile. 312. Some similar habitats are present within Didcot B station, so any loss of these grassland types due to the demolition process is not comprehensive and even in the absence of any mitigation, the impact arising is not as high as it could potentially be. The vegetation on the Site will only be removed where it is required to allow safe access of the demolition vehicles, it is not the intention to strip vegetation where direct access is not required. 313. An area of land adjacent to the coal loop, to the south east of the main stack has been defined as one of the most biodiverse areas on the Site. This area has been fenced and will not be accessed during the demolition period. Information regarding the importance of this area is included in the site induction.

6.4.2.4 Invertebrates 314. The invertebrate community identified within the mosaic of habitats present within the wider study area has been assessed of being of County value. Whilst only a part of the habitat incorporated within the invertebrate survey area would be lost as a result of the demolition, it is nevertheless important as it forms part of wider network used by a population of insects reliant on habitats (and thereby different parts of the Site) at different stages of their life cycle. That being said, other areas within the wider study area will also offer similar niches that will be exploited by the key invertebrates, and in this context the likely worst case scenario is an overall denudation of local carrying capacity and/or population size of scarcer species, rather than local extinction.

6.4.2.5 Great crested newts 315. Although no great crested newts have been recorded within the demolition site boundary, it contains suitable terrestrial newt habitat within 100m of a known breeding pond (see Figure 4, Appendix 17). As newts spend a significant amount of their time away from the pond, there is a possibility that some newts may utilise terrestrial habitat within the northernmost part of the demolition site. Due to the high level of protection afforded to great crested newts a detailed mitigation

strategy will need to be licensed by Natural England prior to works beginning. A licence application was made to Natural England on 24th July 2013. The proposed mitigation is based on the premise of excluding all newts from the demolition site prior to works through a capture, translocation and exclusion scheme, this will ensure that no harm or injury would come to any individual great crested newt. In addition to ensuring that newts are absent from the demolition zone prior to works being undertaken, habitat enhancement measures have been undertaken within the range of the same metapopulation to ensure there is no negative effect on local or wider conservation status and to offer scope for significant gain. In June/July 2013 works were completed to enhance 2 existing ponds within the SCEEC site and create one additional pond to improve breeding opportunities. Delivering these enhancements ensures that the SCEEC site is able to offer an appropriate receptor area for any great crested newts moved from the demolition site, as well as securing overall net gain in metapopulation terms. 316. Mechanisms would be put in place to ensure the long term management and maintenance of these new and/or enhanced features. Overall, it is predicted that there will be a significant positive benefit on the local great crested newt population arising as a consequence of the mitigation proposals.

6.4.2.6 Bats 317. Survey work to date has identified no bat roosts within any trees, nor in any of the buildings due for demolition. The activity surveys undertaken have demonstrated that there is a minimal amount of bat activity on the Site, and that such activity that occurs is overwhelmingly dominated by species that are common and widespread. Those species (and indeed the scarcer Nathusius’ pipistrelle that has also been recorded) do roost in industrial buildings, but generally they do not offer the conditions favoured for maternity or hibernation/winter roosting. It is therefore proportionate and reasonable to predict that any roosts affected by the demolition works in due course are likely to be at the lower end of conservation value. 318. The presence or absence of roosts within specific buildings will be established prior to the demolition of the buildings in question. Any minor roosts encountered (e.g. non-breeding and non-wintering roosts of small numbers of common species) would be dealt with through the normal licensing route using proportionate and tried and tested mitigation solutions (e.g. bat boxes on retained trees or built structures under RWE npower control) to ensure no change in the favourable conservation status of the species concerned. In the unlikely event that more significant roosts (e.g. maternity/breeding roosts) are encountered, or roosts of the scarcer Nathusius’ pipistrelle are found, a more bespoke approach to mitigation would be taken, up to and including the design and provision of purpose-built structures on RWE npower controlled land. 319. In all scenarios however, because of the nature of the roosting opportunities offered by the Site and the generally common status of the species likely to exploit those opportunities, a high degree of confidence can be attached to the conclusion that any impacts on bats can be adequately mitigated in accordance with international and national regulatory requirements. The habitats within the Site currently provide extremely low quality foraging bat habitat as identified through

the paucity of bat registrations recorded throughout the study period. The loss of this habitat is assessed to be not significant in terms of the wider bat population. Corridors of habitat would be retained adjacent to Moor Ditch and along the northern side of the Site, ensuring the retention of a certain amount of habitat for any commuting bats.

6.4.2.7 Birds 320. With the exception of peregrine, the breeding bird population within the demolition site has been assessed as of local value at best. Very few of the features within the buildings have been identified as being utilised by nesting birds; this is in part due to the design of the buildings, as well as the moderately high disturbance resulting from the 24 hour operation of the station. The installation of a number of nest boxes of different designs within the trees that are to be retained, as well as within the neighbouring Sutton Courtenay Environmental Education Centre should ensure the loss of nest sites within the demolition area can be adequately compensated. 321. Peregrine, which is included on Schedule 1 of the WCA, regularly nests on structures associated with Didcot A, although an alternative nest location has also been used within Didcot B in some years. During 2013 Peregrines were found to be nesting at the top of the coal conveyors. For this reason, the coal conveyors were removed at an early stage in the demolition works such that the nest site was removed well outside of the breeding season. To minimise the scope for disturbance or loss of nest site to impact on this species it is planned to install a specifically designed peregrine nesting platform on the OCGT stack. The platform will be installed following completion of the main demolition works to avoid potential disturbance issues. This will provide an alternative nest site location to compensate for the removal of habitually used sites at Didcot A. Such platforms have been successfully installed elsewhere, such as Derby Cathedral. 322. Under Section 1 of the WCA 1981, all birds and their nests receive a certain amount of protection in so far as it may be considered an offence to intentionally damage or destroy an active birds’ nest. Due to the timeframe involved in the demolition process, it will be necessary to undertake some demolition activities during the breeding bird season. Prior to any of these works commencing, an inspection for breeding birds will be undertaken. In the unlikely situation that active bird nests are discovered, works will not be allowed to be undertaken in that specific area until the young have fledged. Overall, with the mitigation and avoidance strategies in place, the residual impact of the demolition process on the local bird population would be negligible.

6.4.2.8 Disturbance to retained habitats 323. The demolition process can be likened to any normal development or construction process in terms of producing disturbance impacts that may impact on surrounding retained habitats. In this instance, impacts from this source also have to be considered in the context of a significant amount of disturbance already resulting from the normal day to day operation of the power station. Whilst the predicted disturbance sources from the demolition process may be different in origin, the impact upon the retained habitats and communities is likely to be similar to the

current disturbance levels. The principal exception would be where explosives are used. Explosives are being proposed for the demolition of the cooling towers and other large structures. Whilst the exact extent of the resultant impacts is difficult to predict due to the unique nature of this process, some broad assumptions can be drawn. The two most significant likely impacts would be the release of dust into the atmosphere and subterranean vibrations. 324. The release of a significant amount of particulate matter into the atmosphere could have a significant impact on any nearby vegetation that is of high value. In accordance with standard practice relating to protecting human health and avoiding nuisance, every effort would be made through a controlled explosion to limit the range of the particulate matter dispersal. Clearly such effects will be most severe in the immediate vicinity of the tower bases. The majority of the surrounding land further afield (e.g. up to 100m) that may be affected is largely industrial; hence the impact upon semi-natural vegetation would be limited. 325. The subterranean vibrations have the potential to impact upon the main badger sett located to the west of the northern cooling towers. However the sett is several hundred metres away on the other side of a major building. It is believed that due to the distance between the source of the blast (if explosive methods are used), in conjunction with the muffling effects of the intervening building’s foundations, that the risk of a significant impact upon the badger sett from the vibrations as a result of the explosions would be negligible.

7 Programme of Works 326. The programme of works is provided in Appendix 18. This will be revised as the demolition project develops and regular updates will be provided to the LPA.

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