Design Guide Proposed Extension to the Allington Integrated Waste Management Facility

July 2020

Contents

 

1 Summary 2 Introduction

2.1 The Proposed Extension

2.2 Purpose of this Design Guide

2.3 Design Advice

2.4 Design Principles

3 Design Codes

3.1 Introduction

3.2 Location, Massing and Form of the Proposed Extension

3.3 Architectural Design

3.4 Materials

3.5 Colour

3.6 Integrated Biodiversity and Landscaping

3.7 Lighting

List of Figures

Front Cover Aerial view of illustrative design

2.1 Illustrative Site Layout for PEIR - Extract from Figure 1.6

3.1 Fourth Line - ‘Fixed‘ Massing - West Elevation - Extract from PEIR figure 5.6d

3.2 Fourth Line - ‘Fixed‘ Massing - South Elevation - Extract from PEIR figure 5.6c

3.3 Fourth Line - ‘Fixed‘ Massing - East Elevation Extract from PEIR figure 5.6b

3.4 Fourth Line - ‘Fixed‘ Massing - North Elevation - Extract from PEIR figure 5.6a

3.5 Fourth Line - Illustrative - East Elevation - Extract from PEIR figure 5.5b

3.6 Fourth Line - Illustrative - North Elevation - Extract from PEIR figure 5.5a

3.7 Fourth Line - Illustrative - South Elevation - Extract from PEIR figure 5.5c

3.8 Fourth Line - Illustrative - West Elevation - Extract from PEIR figure 5.5d

3.9 Proposed Extension - Illustrative - North Elevation - Extract from PEIR figure 5.7a

3.10 Proposed Extension - Illustrative - South Elevation - Extract from PEIR figure 5.7c

3.11 Illustrative Design - Eye Level View from the south east

3.12 Illustrative Design - Aerial View from the north east

3.13 Visualisation from Viewpoint 1: North Downs Way, Blue Bell Hill - Extract from PEIR figure 9.5a(i)

3.14 Illustrative Landscape Masterplan - Extract from PEIR figure 9.6b

 

1 Summary  

Page | 2  

This Design Guide sets out the purpose of the Design Codes and the design development process that the

Design Codes will inform, pursuant to a Requirement within the Development Consent Order (DCO).

This Design Guide contains 30 no. Design Codes which will be applied to the future design of the Proposed

Extension to ensure that the overall design approach is delivered. The Design Codes cover the following:

Location, Massing and Form of the Proposed Extension;

Architectural Design;

Materials;

Colour;

Integrated Biodiversity and Landscaping; and

Lighting.

2 Introduction 

Page | 3  

2.1 The Proposed Extension

FCC Environment (UK) Ltd (‘FCC’ or ‘the Applicant’) is applying for a Development Consent Order (DCO) to

construct, operate, and maintain a proposed extension (‘the Proposed Extension’) to the existing Integrated

Waste Management Facility IWMF (‘the Existing Station’) located at the former Allington Quarry, Laverstoke

Road, 20/20 Business Park, Allington, Maidstone, Kent (‘the Site’). This would include the development of an

additional waste treatment line (‘the Fourth Line’) and associated infrastructure.

The Existing Station has three waste processing lines, which in combination can manage up to 560,000 tonnes

per annum (tpa) of non-hazardous residual waste, generating up to 42 Megawatts of electricity (MWe), of which

34MWe is exported to the National Grid via a dedicated underground grid connection cable. The Proposed

Extension would be capable of processing approximately 350,000tpa of non-hazardous residual waste,

generating approximately 30MWe, of which 26MWe could be exported to the National Grid.

In combination, the Existing Station and the Proposed Extension (hereinafter referred to as ‘the Extended

Station’) would generate in excess of 50MWe at c72MWe. The Proposed Extension is therefore a Nationally

Significant Infrastructure Project (NSIP), requiring a DCO under the Planning Act 2008, with the process of EIA

governed by the Infrastructure Planning (Environmental Impact Assessment) Regulations 2017 (the ‘EIA

Regulations’). The DCO application will be submitted to the Planning Inspectorate (PINS) who will appoint

Inspectors to examine the DCO application and then make a recommendation on the application to the Secretary

of State for Business, Energy and Industrial Strategy (BEIS).

The Proposed Extension would also be capable of exporting heat to local users. Electricity would be generated

by way of a steam turbine connected to an electricity generator. The Proposed Extension would give rise to

incinerator bottom ash (IBA) which would require further treatment off-site at a suitably licensed treatment

facility.

The principal elements forming the Proposed Extension are set out below.

The Fourth Line Main Building

The Proposed Extension as is the case with the Existing Station, would be contained within a main building

consisting of a series of interconnected smaller buildings located to the immediate west of the Existing Station.

The new Fourth Line main building would be orientated in a north south alignment to be parallel with the Existing

Station.  

The Fourth Line main building would contain the elements listed below:

o Tipping Hall;

o Waste Bunker and cranes;

Fig. 2.1 Illustrative Site Layout for PEIR – Extract from PEIR figure 1.6

 

Page | 4   

o a combustion system housed within a Boiler Hall comprising a single combustion line and

associated boilers;

o a steam turbine and generator housed within a Turbine Hall;

o a bottom ash handling system, including storage hall and ash collection bay; and

o a Flue Gas Cleaning Plant, including residues and reagent storage silos and tanks housed

within a Flue Gas Treatment Hall.

Ancillary infrastructure required for the operation of the Proposed Extension includes:

o the ACC;

o a fire water tank; and

o fuel and ammonia tanks.

Shared Stack and associated monitoring system;

A new shared in and out gatehouse and weighbridge arrangement from the existing access off

Laverstoke Road to service the Extended Station;

An extension to the existing sub-station next to the existing staff car park;

A shared district heating centre;

A shared outage compound with associated contractor parking;

New shared surface water drainage infrastructure;

Shared silos for essential materials for the energy recovery process on the site;

A combined control room; and

Shared offices and visitors centre.

A shared security office

 

The Fourth Line main building of the Proposed Extension covers an area of approximately 6.9 ha. As set out

above, it would be housed within a single main building, divided into a series of distinct but interconnected

smaller buildings housing the various process areas as is the case with the Existing Station. The design and

massing of the Proposed Extension is very similar to the Existing Station in that the spatial requirements of each

process element are reflected in the dimensions of the building they are housed within.  

The main building would be approximately 145.6m in length, with the width varying but being approximately

114.2m at the widest point. The existing ground levels where the Proposed Extension is be constructed would

be landscaped and reshaped, creating a flat platform for development of +16 AOD, with the exception of the

Tipping Hall where the platform level would be +18 AOD. 

The height of the main Fourth Line building would differ depending on the various process that the respective

areas house. The highest section of the main building would be the Boiler Hall and would be 37m above the

+16m AOD development platform level. The Flue Gas Treatment Hall would be at a height of 30m above the

 

Page | 5   

+16m AOD development platform level. The Tipping Hall would be constructed at 21m above the +16m AOD

development platform.  

The height of the new Shared Stack has been determined through air dispersion modelling and would reach to

a maximum height of 90m above the +16m AOD development platform level. 

Shared Infrastructure

The Proposed Extension would include a range of components which would be shared with the Existing Station.

The key shared infrastructure elements include the following: -

Control Room

Car Parking

Shared Stack

Continuous Emissions Monitoring Platform

the District Heating Centre

the Outage Compound

Roads and Services Infrastructure

Drainage Infrastructure (all be it extended to cater for the Proposed Extension)

In and Out Weighbridges/Gatehouse complex

Internal Access Roads

Visitor Centre

Lighting

The Proposed Extension and Existing Station would also share managerial and administration Staff

Earthworks

To prepare the Site for the Proposed Extension a new development platform would need to be created. Directly

to the west of the Existing Station is a large bund created from the relocation of inert materials and re-engineering

of the former quarry. It enabled a level platform to be engineered and allowed the Existing Station to be built.

The Proposed Extension would be located, in part, on the location of the footprint of the current existing bund

structure, and part extend further west into the Nature Conservation Area (NCA).

The development of the Proposed Extension would require the NCA to be removed of vegetation, the soils

stripped and earth from the existing bund deposited on the western end of the Site. The eastern half of the NCA

would accommodate the main fourth line building. The western half of the Site would ultimately be restored, and

a new landscape scheme implemented that, whilst over a smaller area than the existing NCA, could offer some

improvements including the provision of public footpaths.

 

Page | 6   

The NCA has limited biodiversity or landscape value and is of little amenity benefit being closed to the public.

Nonetheless, the Applicant recognises that the Extended Generating Station would result in its loss (albeit the

western half can ultimately be brought back into biodiversity habitat and appropriately landscaped). Accordingly,

the loss of the NCA has been subject to assessment by the Applicant in order to determine the extent of any

off-site compensatory habitat that could be created. The aim of the Applicant was to try and identify and create

the opportunity for 10% net overall biodiversity improvement. The options for off-site compensation are detailed

in Chapter 11.0.

In order to create a level development platform, and to ensure that the Extended Generating Station is sufficiently

well screened from off-site viewpoints in much the same manner as the Existing Station, it would require the

movement and profiling of approximately 775,000m3 of inert materials within the Site.

Grid Connection

It would be necessary to provide an additional electrical connection from the sub-station to the National Grid

given that the Existing Station export cable is not sized to accommodate the increased export capacity. It is

proposed that this new cable would be routed via an underground grid connection (33kV) to the Maidstone

substation (located on Lenfield Avenue, approximately 3.5km southeast of the Site), to which the Existing Station

is currently connected. The connection to the National Grid would be undertaken by the DNO under their

statutory powers under the Electricity Act 1989 and permitted development rights as a statutory undertaker.

Accordingly, the works would not fall to be consented under the DCO process. Nonetheless, consideration has

been given within the Chapters of the PEIR to the likely impacts associated with the installation of the Grid

Connection because the connection to the network is a critical requirement for the Proposed Extension.

The Existing Station is connected to the Maidstone Sub-Station via an underground connection that runs east

around the 20/20 business park and then south through a number of land uses and suburban areas on northern

Maidstone (Route A). The existing route is subject to a number of technical, environmental, physical and legal

constraints which led the Applicant (in consultation with the DNO) to consider whether an alternative route may

be preferable (Route B). Accordingly, there are two potential grid connection routes for the Proposed Extension,

as follows:

Route A: the existing route from the Existing Station, running through undeveloped and suburban

areas towards the northern edge of Maidstone;

Route B: an alternative route that follows the A20, and roads within Maidstone town centre.

For either Route it is anticipated that a working trench of 350mm would be required with a 1.5m-2.5m wide

running track and up to 6m width required for stockpiling of excavated materials and for access. Where feasible,

any vegetation lost to construction would be reinstated.

 

Page | 7   

In relation to Route A, the new trench would need to be located at least 1.5m from the existing cable easement

to avoid disturbing this, thereby increasing the required land take. In order to excavate the trench, some

temporary disturbance would be required to the woodland area in the north-eastern part of the Site itself, to the

woodland outside of the Site boundary north of the 20/20 Business Park, and to Lock Wood (located south of

Allington Lock). Further disturbance would be required to the area of public open space south of Allington Castle,

to undeveloped areas on either side of the River Medway (including the recreation ground off Dickens Road), to

Invicta Park, to recreation grounds off Sandling Lane and Penenden Heath Road, and to a residential area east

of the A249. In some cases, this may require tree removal, and/ or temporary restrictions to public access.

Route B would be buried within a trench located within the verge and / or carriageway of the A20 and town

centre roads. There would be some temporary disturbance of verge vegetation (grassland and small shrubs) to

excavate the route of the cable. There may be temporary restrictions to public access along the roads, or

temporary traffic restrictions required.

Route B has been subject to a walkover undertaken by a representative of the DNO (UK Power Networks -

UKPN), their construction and environmental contractors and representatives from the Applicant. The purpose

of the walkover was to identify and understand any potential environmental, operational and construction

constraints that may influence the final route selected. A record was taken of the constraints identified during

the walkover and the discussions held with UKPN representatives. The Applicant has held subsequent dialogue

with the UKPN which has culminated in an application having been made for grid connection. In advance of

receipt of this offer, the Applicant has requested that UKPN undertake a detailed desktop route assessment and

engage directly with KCC Highway Authority and other statutory bodies along the proposed route to confirm the

approach that could be followed in terms of temporary traffic control during the installation of any grid connection.

The assessment undertaken by UKPN will be used to support the submission of the DCO application.

Route B is the current preferred route and leaves the Site along Laverstoke Road and then turns west onto St

Laurence Avenue where it continues to the Coldharbour roundabout. The route then follows the A20 London

Road in a south easterly direction, under the Maidstone to Bromley railway line, towards Maidstone. There are

a number of Grade II listed buildings along this section of the route to the west of the A20. Just before the A20

/ A26 interchange the route leaves the public highway in an easterly direction to follow Buckland Road where it

crosses the Strood to Paddock Wood / Tonbridge railway line and past a Grade II Listed former church before

meeting St Peters Street. The cable route will then subject to the DNO review then pass over the Medway River

via either the Broadway Bridge or the St Peters Bridge[1] and then onto the A229. From here the route runs in

an easterly direction along the High Street where there are numerous Grade II listed buildings before following

Kings Street where there are again a number of Grade II listed buildings located to the south. The route then

 

 

Page | 8   

carries on over a gyratory roundabout, where a further two Grade II listed buildings are located to the south,

before heading onto the A20 Ashford Road. The cable route then crosses a railway line before turning north

onto Huntsman Lane, where there is a Grade II listed building. Finally, the cable route turns northwest onto

Lenfield Avenue where the substation is located.

Rigid corrugated cable ducts would be laid within a trench excavated to a minimum depth of 3m using a wheeled

excavator or similar. It is anticipated that hardstanding would be broken out using a hand operated or machine

mounted pneumatic breaking hammer and mechanical road saws. The cabling duct would be placed on a

blinding layer of sand or screened earth to prevent damage from sharp objects. A further blinding layer would

then be placed on the ducting. For the purposes of health and safety, marking tape or tiles would be laid

approximately 75mm above the duct to indicate the location of the duct. The trench would then be backfilled

with the previously excavated material. The electric cabling would be pulled through the ducting once the ducting

had been laid and secured in position.

2.2 Purpose of this Design Guide

As described within the Design Evolution Statement there are number of components forming the Proposed

Extension that due to the level of detail design that has been undertaken to date the Applicant considers to be

fixed and where future flexibility is not required. This covers the Fourth Line main building and the components

are recorded in a series of drawings which can be found in Chapter 5 of the PEIR and which define its fixed

massing in terms of its footprint; heights; roof forms and the overall spatial relationships of the functions forming

the Fourth Line.

The location of the Proposed Extension on the Site is also fixed, as are the AOD levels of its development

platforms.

However, the detailed design of a large part of the Proposed Extension has yet to be finalised. This design

process will continue and will not be concluded until after any grant of the DCO application. The Applicant is

therefore seeking consent for these components on the basis of them being defined within a ‘reasonable worst

case’ envelope, one which reflects the maximum possible parameters for each of the buildings, structures, plant

and equipment where future design flexibility is required. If the DCO is granted, the future detailed design of

these components will be developed within the defined Design Parameters, and (where applicable) in

accordance with the Design Codes contained within this document and where required by the DCO

requirements, will be submitted to the Local Planning Authority for approval prior to the commencement of

construction.

 

Page | 9   

This approach is common in large infrastructure projects and provides a degree of design flexibility within clearly

defined parameters. This flexibility ensures that a satisfactory and deliverable scheme can be implemented and

allows for adaptability and efficiency through the future design process.

This document provides Design Codes for elements of the Proposed Extension. The draft DCO will require

detailed design of these elements to be submitted to the local planning authority for approval and to be in

accordance with these Design Codes. The Design Codes will therefore guide the design development of the

specified above-ground works within the Site and ensure that opportunities to mitigate the visual and landscape

effects of the development are considered and implemented where practicable.

Further information about the design evolution of the Proposed Extension that has led to the development of the

Design Codes is presented in the Design Evolution Statement (DES) and this Design Guide should be read

alongside the DES.

The purpose of this Design Guide is:

To provide further design information for the purposes of the Environmental Impact Assessment (EIA) of

the Proposed Extension;

To provide stakeholders with an understanding of how the design of the Proposed Extension will be

developed following grant of DCO;

To set out design related issues raised in response to public consultation and to ensure that, where

practicable, these are addressed through detailed design;

To provide certainty that the Proposed Extension would be consistent with good design principles whilst

maintaining necessary flexibility on design details; and

To demonstrate an ongoing commitment to ‘good design’, as defined in National Policy Statements,

ensuring the Proposed Extension is sustainable, resilient and aesthetically appropriate.

The Illustrative Site Plans and Elevations submitted with the DCO will provide an indication of how a detailed

design developed in line with the Design Codes might appear.

2.3 Design Advice

During the design evolution process the use of the Kent Design Guide was initially considered as a way in which

the developing design of the Proposed Extension could be assessed against its wide range of ‘good design’

principles. However, while this is an excellent guide for the design of a wide range of building types it was found

to be less suited in assessing the specific design requirements associated with the Proposed Extension. For

that reason, it was decided that as part of the design evolution process we would refer to and draw upon the

design guidance offered by the following document.

 

Page | 10   

"A design-led approach to infrastructure" CABE/ Design Council: November 2012 Reference has been made to this CABE/ Design Council publication. It seeks to promote a design-led approach

to large infrastructure projects to ensure that the opportunity for these projects to offer a positive response to

their setting is not overlooked, and that without compromising their purpose and function deliver a confident and

well considered architectural design. This guidance was considered to be more appropriate for the design of the

Proposed Extension and how the design has embraced the Ten Design Principles is detailed below.

Setting the scene The Applicant has recognised from the outset that the Proposed Extension would require careful consideration

of its setting within the Site and that a typical ‘industrial shed’ design approach would not be appropriate. It was

also acknowledged that a creative design which did not conflict with the functional and operational requirements

of the Existing Station but would complement it and be an integral part of the design approach for the Proposed

Extension .

Multi-disciplinary teamwork In designing the Proposed Extension, the Applicant has embraced the principles of collaborative teamwork and

effective consultation. The architect and landscape architect have been key members of the project team and

working closely with the FCC technical team has allowed the technical and architectural design of the project to

be developed in parallel rather than in isolation from each other. Furthermore, the Applicant has selected a

design team that has a wealth of experience in the design of similar facilities but also with a successful track

record of working together. The team has also includes a wide range of consultants who, being specialists in

their fields, have influenced the design evolution process to ensure that the potential impacts of the development

could be identified, and appropriate mitigation and enhancement measures imbedded in the design. The layout

of the Site has, where possible, been developed to improve the Proposed Extension’s relationship with its

surroundings.

The bigger picture The project team are continuing to explore the opportunities for the Proposed Extension to have a broader

influence in the area. The Proposed Extension would be a significant investment within Kent and would offer job

opportunities in addition to those currently provided by the Existing Station.

The Applicant is fully aware of the benefits that district heating could offer the surrounding area. For that reason,

the potential for the Proposed Extension to provide district heating is currently being explored and the Heat

Plan submitted with the PEIR provides more information on this. Appendix 5-6 of the Chapter 5

Site masterplan The context and surroundings of the Site have heavily informed the layout of the Site. This has included the

location of buildings and external equipment and the layout of the road infrastructure required to serve these.

Minimising the overall footprint of the Proposed Extension has been a key feature of the design in order to

 

Page | 11   

maximise the areas within the Site that could be developed for landscaping and biodiversity enhancement, and

to use these landform areas to continue to contribute to mitigating the visual and noise impacts upon the

surrounding area.

Landscape and visual impact assessment Due to the scale of the Proposed Extension, assessments of the visual impact and landscape character were

instrumental in determining its layout and architectural design. The developed LVIA photomontages allowed

there to be careful consideration of the suggested cladding materials and colours.

Landscape design The landscape architect and ecologist have worked closely to develop a multi layered landscape design, one

which uses existing and re profiled perimeter earth bunding to best utilise the excavated material required to be

relocated for the Proposed Extension development platform and which will continue to provide visual and noise

mitigation around the Site’s perimeter.

Design approach From the outset it has been recognised that due to the scale and the setting of the Proposed Extension it will be

impossible for the Fourth Line main building to be ‘hidden’, and that while it would be important for it to be

designed in such a way as to best mitigate its visual impact, it would nevertheless be a large building and as

such it should make a positive and confident architectural statement, which at the same time gives due

consideration to its surroundings and context. The Proposed Extension embraces this design approach and

applies a clear architectural concept which when read alongside the Existing Station presents an integrated

family of buildings.

Materials and detailing Not surprisingly for a development of this nature, metal cladding is suggested as the predominant cladding

material to be used across the Proposed Extension. The suggested cladding systems are robust and of low

maintenance and their durability (i.e. colour retention and corrosion resistance) will ensure that the high quality

appearance of the Proposed Extension will be retained over time.

Sustainability Where possible the size and volumes of the fixed building components are designed to be as volumetrically

efficient as possible in order to minimise the use of materials, and materials have been chosen for their longevity

and/or robustness as well as their visual appearance. The need for rooflights has been balanced with the need

to mitigate the potential night-time visual impact of the Proposed Extension, and as a result have roof lights are

excluded from the design.

 

Page | 12   

Visitor Centre The Extended Station will still utilise the existing visitor centre facilities provided by the Existing Station and will

continue to be available for visits by local interested parties during normal opening hours. FCC has a history of

supporting education and research projects and specific provision will continue to be made for the presentation

of the facilities and operations as a resource for local schools and educational establishments.

2.4 Design Principles

From the outset it has been recognised that the Proposed Extension can be appropriately designed to fit well

within its setting while at the same time taking due consideration of the Existing Station, and a range of design

principles have influenced the design development process.

The principle architectural design objectives have been to:

Minimise the scale of the Fourth Line main building by adopting a ‘form follows function’ design approach

and avoiding more ‘sculptural’ designs which would stray from being volumetrically efficient;

Optimise the potential to share functions and infrastructure with the Existing Station; and

Where appropriate repeat the architectural principles of the Existing Station.

A wide range of other design principles were considered important in developing the proposed design and these

included:

Minimising the Fourth Line building footprint;

Minimising where possible the individual building sizes (heights and volumes);

Establishing a logical and efficient process arrangement in the layout of the Fourth Line main building;

Segregating as far as possible operational HGV access from staff and visitor vehicular access;

Ensuring intuitive, efficient and safe traffic management for all vehicles circulating within the Site and

integrating the new and existing traffic systems;

Ensuring HGVs have optimal right hand down reverse turning when manoeuvring around the Site;

Minimising the extent of external plant and equipment;

Providing adequate queuing and manoeuvring space for all vehicles within the Site;

Ensuring that the massing and scale of the development and the earthworks design are developed such

that they best mitigate the potential visual and noise impacts; and

Developing a successful landscaping strategy which ecologically and visually enhances the Site while at

the same time provides additional visual screening.

The design of the Proposed Extension has been developed to respond to both the key site constraints and the Design Principles identified above. Requiring the detailed design to be developed in accordance with the Design Codes will ensure these design objectives are met.

3 Design Codes 

Page | 13  

3.1 Introduction

The following Design Codes will be applied in developing the future detailed design of the Proposed Extension

and will be submitted to the Local Planning Authority for approval under the DCO Requirements.

The Design Codes cover aspects of the design which are considered ‘fixed’ as well as those aspects where

future ‘flexibility’ is required, and where applicable proposed mitigation measures are identified against each.

In determining the Design Codes consideration has been given to how the Proposed Extension might best relate

to the Existing Station to achieve a ‘family of buildings’ on the Site. We have also drawn upon an illustrative

design for the Proposed Extension which has been developed to:

test the maximum extent of design parameters;

establish a ‘fixed’ basic massing for the Fourth Line main building upon which the required environmental

assessments could be based; and

identify the required range of Design Codes.

 

Page | 14   

3.2 Location, Massing and Form of the Proposed extension

As a result of the extent of detailed design work undertaken during the pre-application stage it has been possible

to fix the design of some components of the Proposed Extension. These components relate to the Fourth Line

main building and are defined on the basic massing drawings (Figs 3.1; 3.2; 3.3 & 3.4) and on the Works Plan

drawing all of which are located within Chapter 5 of the PEIR.

The first series of Design Codes cover these ‘fixed’ design components.

The preferred north/south orientation of the Proposed Extension was chosen over an east/west

arrangement as it matched the linear process arrangement of the Existing Station;

Optimised the potential of shared infrastructure between the two;

Best mitigated visual and noise impacts on nearby receptors.

The arrangement of the Existing Station on the Site determined that the Proposed Extension would have

to be located on its western side to allow for the ongoing operation of the Existing Station during the

construction of the Proposed Extension and to minimise the impact upon existing roads and services

infrastructure.

DC 1.01

The Fourth Line main building will be designed to a north to south orientation to

match the alignment of the Existing Station and as defined on the Works Plan

drawing. 

DC 1.02

The Fourth Line main building will be located on the western side of the Existing

Station as defined on the Works Plan drawing. 

DC 1.03

The Fourth Line main building will in both shape and area be as the footprint

defined on the Works Plan drawing. 

Fig. 3.1 Fourth Line - ‘Fixed‘ Massing – West Elevation – Extract from PEIR figure 5.6d

Fig. 3.2 Fourth Line - ‘Fixed‘ Massing – South Elevation – Extract from PEIR figure 5.6c

 

Page | 15   

As described in the DES the regular interface between the FCC technical team and technology supplier

during design development has allowed the design to be reviewed in detail and enabled the footprint and

shape of the Proposed Extension to be determined. around the process functions. As such the shape

and footprint of the Fourth Line main building is fixed .

A similar level of detail design has determined the volume requirements of each building and as such

the roof heights have been fixed. This has minimised its overall scale to best mitigate its visual impact;

Ensures it relates well with the Existing Station.

The combination of fixing the footprint and the roof heights of the various process areas has resulted in

its interlocking volumes and stepped profile. This has generated its overall massing and form which best

mitigates its visual impact;

Ensures that it reads well with the Existing Station.

From the outset there has been a desire to repeat some of the architectural features of the Existing

Station on the Proposed Extension. One of the features being repeated is the sweeping curved roof

forms which would minimise its overall massing;

Establishes a visual link with the Existing Station to help create a ‘family of buildings’ on the Site.

DC 1.04

The Fourth Line main building roof heights will be as defined on the basic massing

drawings. 

DC 1.05

The Fourth Line main building in its massing and form will be as defined on the

basic massing drawings. 

DC 1.06

The Fourth Line main building will have sweeping curved roof forms to match

those of the Existing Station and as defined on the basic massing drawings. 

Fig. 3.3 Fourth Line - ‘Fixed‘ Massing – East Elevation – Extract from PEIR figure 5.6b

Fig. 3.4 Fourth Line - ‘Fixed‘ Massing – North Elevation – Extract from PEIR figure 5.6a

 

Page | 16   

The platform levels have been determined through detailed assessment of the Site and relationship with

the Existing Station. As such the main platform level for the Fourth Line main building is set at +16 AOD.

This aligns with the northern end of the Existing Station keeping the tallest parts of the Fourth Line main

building on the lowest level thereby reducing its visual impact;

It also optimises operational connectivity and shared infrastructure with the Existing Station. Setting the

Proposed Extension’s Tipping Hall at +18 AOD reduces the extent of excavation and vehicle ramp

lengths between the southern and northern area of the Site;

Assists in reducing noise due to this arrangement by maximising the screening benefit from the existing

perimeter bund to the south.

To visually soften the roof edges and to ensure that the sweeping roof forms are achieved to add visual

interest;

To be in keeping with those on the Existing Station in order to support the design principle of a ‘family of

buildings’ across the Site.

DC 1.07

The Fourth Line main building will have development platform levels as defined

on the basic massing drawings. 

DC 1.08

The roof eaves for the Fourth Line main building will project beyond the facade

and be in ‘bull-nose’ profile to be in keeping with that on the Existing Station. 

 

Page | 17   

3.3 Architectural Design of the Fourth Line

The remaining ‘flexible’ design components of the Fourth Line main building are covered by design parameters.

In order that these worse case design parameters could be determined and to ensure that the ‘fixed’ basic

massing of the Proposed Extension was achievable, an illustrative design was developed for the Fourth Line

main building. This has informed our understanding of how the design may be developed in future and has also

enabled us to define the following Design Codes to guide that process.

To add visual interest and break up the scale of the building;

To be in keeping with those on the Existing Station in order to support the design principle of a ‘family of

buildings’ across the Site.

To add visual interest and break up the scale of the Fourth Line main building .

To maintain the clean lines and balanced appearance of the overall design.

DC 2.02

The location of ventilation louvres will be carefully considered and be flush

mounted to maintain the clean lines and visual balance of the overall design.  

DC 2.01

The location of windows will be carefully considered and will be of horizontal or

vertical ‘ribbon’ design to maintain the clean lines and visual balance of the overall

design and to be in keeping with the Existing Station.  

DC 2.03

The location of roller shutter doors will be carefully considered to maintain the

clean lines of the overall design and where in number should be equally spaced. 

Fig. 3.5 Fourth Line - Illustrative - East Elevation – Extract from PEIR figure 5.5b

Fig. 3.6 Fourth Line - Illustrative - North Elevation – Extract from PEIR figure 5.5a

 

Page | 18   

To assist in visually breaking up the overall scale of the Fourth Line main building to mitigate its visual

impact;

To be in keeping with those on the Existing Station in order to support the design principle of a ‘family of

buildings’ across the Site.

To best mitigate visual impact;

To maintain the visual quality of the overall design.

To visually differentiate the Technical Block from the rest of the Fourth Line main building ;

To mitigate the potential visual impact of rooftop plant;

To provide permanent roof edge protection for service personnel.

DC 2.04

Rainwater downpipes are to be circular in profile and surface fixed to the wall

cladding to add visual interest and break up the overall scale of the building. 

DC 2.05

The location of rooftop equipment will be carefully considered with the size of

individual pieces of equipment being minimised and their setting out is to be

balanced in order to avoid where possible ‘visual clutter’ and to maintain the clean

lines and visual balance of the overall design.  

DC 2.06

Parapet roof edges are to be applied to the Technical Block and set to a height to

visually conceal any rooftop plant/equipment.  

Fig. 3.7 Fourth Line - Illustrative - South Elevation – Extract from PEIR figure 5.5c

Fig. 3.8 Fourth Line - Illustrative - West Elevation – Extract from PEIR figure 5.5d

 

Page | 19   

To maintain the cubic forms of the overall design approach;

To mitigate its visual impact;

To be in keeping with the Existing Station in order to support the design principle of a ‘family of buildings’

across the Site.

DC 2.07

The upper part of the Air Cooled Condensers are to be clad in vertical cladding. 

Fig. 3.9 Proposed Extension - Illustrative - North Elevation – Extract from PEIR figure 5.7a

 

Page | 20   

3.4 Materials

The materials used to construct the Proposed Extension will be high quality, robust and consistent with the

Existing Station, and to minimise visual impact, the use of highly reflective materials will be avoided to minimise

glare.

Where appropriate the materials on the Proposed Extension should match the materials used on the Existing

Station in order to establish a ‘family of buildings’ across the site.

The following Design Codes will inform the future selection of cladding materials.

To ensure that the cladding will maintain its visual appearance over time.

To establish a ‘family of buildings’ across the Site.

To ensure that cladding is appropriately robust and if damaged can be easily replaced.

To ensure that the cladding will maintain its visual appearance over time.

To ensure that the sweeping roof forms are achieved and that they will be in keeping with those on the

Existing Station.

To maintain overall design approach and establish a ‘family of buildings’ across the Site.

DC 3.01

The wall cladding systems will employ robust, easily maintainable, and

replaceable materials appropriate for the industrial environment. The cladding is

to be predominantly twin skin construction and in keeping with the Existing Station

it will have a horizontally orientated trapezoidal profiled steel outer skin.

DC 3.02

The roof cladding systems will be robust and easily maintainable. On the Fourth

Line main building they should be able to ‘self-form’ to achieve the shallow roof

curves and will have a standing seam profile in keeping with the Existing Station.

DC 3.03

The cladding used for ancillary buildings (i.e. District Heating Centre; Pump

House; Gatehouse etc.) will match those being used on the Fourth Line main

building.

Fig. 3.10 Proposed Extension - Illustrative - North Elevation – Extract from PEIR Figure 5.7c

 

Page | 21   

3.5 Colour

In developing the illustrative design of the Proposed Extension, it has been necessary to review how colour

might contribute to mitigating its visual impact. It was initially considered that the most appropriate approach for

selecting the colours of the Fourth Line main building would be to match those used on the Existing Station and

to maintain the principle of the common architectural approach and family of buildings across the Site. In

matching the colours, the cladding on drawings and visuals was coloured to best match those of the Existing

Station (Figs. 3.11 & 3.12):

Roof Cladding - Natural aluminium Standard Stucco-embossed finish will weather to provide over time a mid-

grey patina over the whole roof area.

Wall Cladding - Pastel Green: RAL 6019

Fig. 3.12 Illustrative Design – Aerial View from the north east

Fig. 3.11 Illustrative Design – Eye Level View from the south east

 

Page | 22   

However, when these colours were tested in a key photomontage view from the Area of Outstanding Natural

Beauty (ANOB) lying to the north of the Site (Fig 3.13), the pre- application consultation with the AONB unit

established that there was distinct preference for a darker roof colour than that on the Existing Station. The

montage views were revisited to include a darker grey on the roof of the main building and also tested a darker

green for the wall cladding as it was considered that the Pastel Green tended to stand out more against the

backdrop and this would be emphasised even more when read with a darker grey roof. This concluded that the

cladding of the Fourth Line main building should not match the Pastel Green walls and natural aluminium finish

roof of the Existing Station. For those reasons the following colours were considered in order to best mitigate its

visual impact when viewed from the AONB and to complement those of the Existing Station.

Roof Cladding - Merlin Grey: RAL 180 40 05

Wall Cladding - Moorland Green: RAL 10 60 20

Fig. 3.13 Visualisation from Viewpoint 1: North Downs Way, Blue Bell Hill - Extract from PEIR figure 9.5a(i)

 

Page | 23   

These colour studies have informed the following Design Codes which will guide the future selection of colours

for the Proposed Extension.

To mitigate its visual impact from distant elevated viewpoints.

To complement the colour of the Existing Station.

To assist in visually breaking up the overall scale of the Fourth Line main building to mitigate its visual

impact.

To mitigate its visual impact from distant elevated viewpoints.

To add visual interest and break up the overall scale of the buildings.

To repeat the design approach adopted on the Existing Station.

DC 4.02

The colour of the cladding to the facade of the Technical Block and to the Air

Cooled Condensers will contrast with that on the Fourth Line main building to

generate visual interest and to break up the scale of the Proposed Extension.  

DC 4.01

The colour of the wall cladding of the Fourth Line main building is to be darker in

colour than that of the Existing Station to mitigate its visual impact.  

DC 4.03

The colour of the roof cladding of the Fourth Line main building is to be ‘grey’ in

colour but be darker than that of the Existing Station to mitigate its visual impact.  

DC 4.04

The colour of roller shutter doors and personnel doors are to be in a contrasting

colour to the surrounding cladding.  

 

Page | 24   

To maintain the clean lines and balanced appearance of the overall design.

To add visual interest and break up the overall scale of the buildings.

To repeat the design approach adopted on the Existing Station.

To add visual interest and break up the overall scale of the buildings.

To repeat the design approach adopted on the Existing Station.

To mitigate their visual impact from distant elevated viewpoints.

DC 4.05

The colour of ventilation louvres is to match that of the surrounding cladding.  

DC 4.06

The colour of rainwater downpipes is to match that of the roller shutter and

personnel doors.  

DC 4.07

The colour of window frames is to match that of the roller shutter and personnel

doors.  

DC 4.08

The colour of rooftop plant and equipment is to be consistent and is to match that

of the roof cladding upon which it is located.  

 

Page | 25   

To repeat the design approach adopted on the Fourth Line main building ;

To establish a ‘family of buildings’ across the Site.

To mitigate its visual impact.

DC 4.09

The colour of cladding on ancillary buildings (i.e. District Heating Centre; Pump

House; Gatehouse ACC etc.) will match that of the Fourth Line main building.  

DC 4.10

The Shared Stack will use a neutral light colour to best blend it when read against

a backdrop of sky.

 

Page | 26   

3.6 Integrated Biodiversity and Landscaping

The illustrative landscape proposals for the Proposed Extension (Fig 3.14) have been developed to achieve a

number of key objectives, these being to maximise biodiversity within the Site, to reinforce the screening of

views of the Existing Station and Proposed Extension from outside, and to improve recreational and amenity

benefits through new public access of the land to the west of the Proposed Extension. The proposals would

comprise the retention of existing woodland, scrub and grassland vegetation in the eastern part of the Site,

together with the creation of new habitats in the areas that would be physically disturbed as a result of the

Proposed Extension. New habitats would include new native woodland, species-rich grassland, native scrub,

open mosaic habitat and native hedges. The western part of the Site would be publicly accessible, via St

Laurence Avenue.

 

 

 

 

 

Respecting operational requirements - opportunities would be explored to maximise the extent of low

level landscaping in order to screen low-level ‘clutter’ which would include personnel and vehicle

movements around the site;

Landscaping would be designed with regard to security fencing and CCTV infrastructure;

Appropriate treatment and control of invasive non-native species to prevent spread and contamination

of the Site;

Use of native planting species wherever appropriate in accordance with an Authority agreed planting

schedule;

Hard landscape materials will be selected for visual appearance, ease of maintenance and high

durability;

Wherever appropriate links would be sought with adjacent habitats, and thereafter retained and

enhanced where possible.

DC 5.01

The planting design will contribute to improved nature conservation and

biodiversity benefits, visual amenity and screening, and to help define the public

access routes through proposed permissive footpaths. It would support the

wayfinding strategy and help connectivity with the built and natural structures.

Fig. 3.14 Illustrative Landscape Masterplan – Extract from PEIR figure 9.6b

 

Page | 27   

3.7 Lighting

The Proposed Extension would require additional external lighting to compliment the lighting already on site to

ensure the safe movement of vehicles and pedestrians, for any external amenity areas and for the security of

employees and visitors. The lighting would be the same or similar to that used for the rest of the Site. 

The draft lighting design for the Proposed Extension is described in Appendix 5-2. The appendix assesses light

intrusion, glare, light spillage and ‘sky-glow’ resulting from the Existing Station and the Proposed Extension, and

provides an indicative lighting design that would provide for safe and well-lit external spaces and pedestrian

walkways in accordance with the principles outlined in the guidance documents set out above. Lighting levels

would be designed to accord with best practice and to minimise the generation of obtrusive light beyond the

Site. 

 

 

 

 

 

 

Intelligently designed low-glare fully shielded fittings pointing downwards will be used;

The lighting design relevant to the Existing Station would be designed to meet the specification and

requirements set out within the Landscape & Visual and Ecological Lighting Assessment July 2020;

The lighting design would employ the use of baffles where necessary and appropriate;

Subject to meeting the operational and safety requirements, lighting will be designed to reduce the

brightness and spread of light during operation;

The lighting design will be determined by operational requirements for both day-time and night-time

lighting of buildings and external areas whilst mitigating impacts on local amenity;

The lighting design will provide adequate lighting for vehicular, pedestrian and cyclist movements;

The lighting design will deliver robust and efficient lighting which creates an attractive and safe

environment for staff and visitors;

Building façades will not be lit for architectural purposes above its operational and safety requirements;

The permissive footpaths would not be lit and not open to the public during hours of darkness.

DC 5.02

Lighting will be appropriate to the local context and will mitigate lighting impacts

(‘glare’, ‘light intrusion’, sky-glow’ etc.). It will ensure safe operation of the

Extended Generating Station in accordance with British Standard, Health and

Safety Legislation and Best Practice Guidance.