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Design Evolution Statement Proposed Extension to the Allington Integrated Waste Management Facility
July 2020
Contents
1 Introduction 1.1 Introduction
1.2 Purpose of the Design Evolution Statement
1.2.1 Introduction
1.2.2 Planning Policy
1.2.3 Approach to Design Parameters
1.2.4 Design Advice
2 The Proposed Extension
2.1 Overview
2.2 Key Components of the Proposed Extension
2.2.1 The Fourth Line
2.2.2 Shared Infrastructure
2.2.3 Earthworks
2.3 Grid Connection
3 Site Overview
3.1 Site Location
3.2 Site Description
3.2.1 Surrounding Area
3.2.2 Site Opportunities and Constraints
3.2.3 Site Photographs
3.3 Site History
3.4 Site Analysis
3.4.1 The Site
3.4.2 Access
3.4.3 Site Opportunities and Constraints
4 Design Principles
4.1 Overview of the Design Principles to Date
4.2 Design Principles
5 Design Evolution
5.1 Introduction
5.2 Illustrative Site Layout
5.2.1 Initial Layout Studies
5.2.2 Developed Layouts
5.2.3 Refined Layouts
5.2.4 Final Illustrative Layout for PEIR
5.3 Building Massing
5.3.1 Initial Massing Study
5.3.2 Developed Massing Study
5.3.3 Final Massing Study
5.4 Landscape and Ecology
5.4.1 Landscape
5.4.2 Ecology
6 Design Parameters
6.1 Introduction
6.2 ‘Fixed’ Design Parameters
6.3 ‘Flexible’ Design Parameters
6.3.1 Works Plan
6.3.2 Design Parameters Table
6.3.3 Illustrative Parameters Drawings
7 Conclusion
List of Figures Front Cover Aerial view of illustrative design 1.1 Site Location Plan 2.1 Illustrative Site Layout for PEIR - Extract from PEIR figure 1.6 2.2 Illustrative Connectivity Diagram - Extract from PEIR figure 5.4 2.3 Illustrative Process Flow Diagram 3.1 Existing Site Layout - Extract from PEIR figure 1.2 3.2 Surrounding Area - Photograph Location Plan 3.3-12 Site Photographs A - I 3.13 Site Analysis and Site Photograph Locations 3.14-18 Site Photographs 1 - 5 3.19 Existing Station Layout – Extract from PEIR figure 1.2 5.1 Initial Layout 1 5.2 Initial Layout 2 5.3 Developed Layout 3 5.4 Developed Layout 4 5.5 Refined Layout 5 5.6 Refined Layout 6 5.7 Layout 6 - Connectivity Diagram 5.8 Layout 7 - Vehicle Tracking Diagram 5.9 Final update – Process Areas Adjustments 5.10 Illustrative Site Layout for PEIR- Extract from PEIR figure 1.6 5.11 Initial Massing Study - Longitudinal Section 5.12 Initial Massing Study - Eye Level Views 5.13 Initial Massing Study - Aerial View 5.14 Developed Massing Study - Eye Level View from the south east 5.15 Developed Massing Study - Longitudinal Section 5.16 Developed Massing Study - Aerial View from the north east 5.17 Illustrative Landscape Masterplan 6.1 Fourth Line - ‘Fixed‘ Massing - North Elevation - Extract from PEIR fig. 5.6a 6.2 Fourth Line - ‘Fixed‘ Massing - East Elevation - Extract from PEIR fig. 5.6b 6.3 Fourth Line - ‘Fixed‘ Massing - South Elevation - Extract from PEIR fig. 5.6c 6.4 Fourth Line - ‘Fixed‘ Massing - West Elevation - Extract from PEIR fig. 5.6d 6.5 Proposed Extension - Works Plan - Extract from PEIR figure 5.13 6.6 Parameters Table 6.7 Illustrative Parameters of Deviation - Extract from PEIR figure 5.12a 6.8 Illustrative North Elevation - Parameters of Deviation – Extract from PEIR figure 5.12b 6.9 Illustrative East Elevation – Parameters of Deviation – Extract from PEIR figure 5.12c 6.10 Illustrative South Elevation – Parameters of Deviation – Extract from PEIR figure 5.12d 6.11 Illustrative West Elevation – Parameters of Deviation – Extract from PEIR figure 5.12e 6.12 Illustrative East Elevation (inc. substation) – Parameters of Deviation – Extract from PEIR figure 5.12f
1 Introduction
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1.1 Introduction
This Design Evolution Statement (‘DES’) has been prepared on behalf of FCC Environment (UK) Ltd (‘FCC’ or
‘the Applicant’) to accompany the Development Consent Order (DCO) application to construct, operate, and
maintain a Proposed Extension (‘the Proposed Extension’) to the existing energy from waste (EfW) generating
station (‘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 and treatment lines, which in combination can manage up to
560,000 tonnes per annum (tpa) of non-hazardous residual waste, generating up to 45 Megawatts of electricity
(MWe), of which 38MWe is exported to the National Grid. The Proposed Extension would be capable of
processing approximately 350,000tpa of non-hazardous residual waste, generating approximately 32MWe, of
which 29MWe is proposed to be exported to the National Grid.
In combination, the Existing Station and the Proposed Extension (hereinafter referred to as ‘the Generating
Station’) would generate in excess of 50MWe at c77MWe. The Generating Station is therefore considered to be
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 as the Examining Authority who will assess the application and then make a recommendation
to the Secretary of State for Business, Energy and Industrial Strategy (BEIS) who will make the final decision.
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 comprises the following main elements:
An additional waste treatment line (‘the Fourth Line’) incorporating;
a waste reception area (tipping hall, storage bunker and cranes);
a combustion system housed within a boiler house comprising a single combustion line and
associated boilers;
a gas cleaning system, including residues and reagent storage silos and tanks;
a steam turbine and generator housed within a turbine hall;
a cooling system comprising air cooled condenser (ACC) units;
a bottom ash storage and collection bay;
offices, welfare accommodation, and localised control room;
fuel and ammonia tanks; and
fire water tank and pump house.
Fig. 1.1 Site Location Plan
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A range of elements to be shared with the Existing Station;
Shared Stack and associated emissions monitoring systems;
a shared control room and storage facilities located within the Existing Station;
a shared district heating centre;
a shared outage compound with associated contractor parking and permanent and temporary
cabins;
shared offices located within the existing main reception building;
a shared access from the public highway and part shared internal access arrangement;
a shared new gatehouse and weighbridge arrangement from the existing access off Laverstoke
Road;
new shared replacement sub-station next to the existing staff car park;
a new electrical grid connection to complement the existing connection;
new shared and extended surface water drainage infrastructure; and
new roads and vehicle circulation areas.
FCC is one of the UK’s leading waste and resource management companies. Its approach is to minimise the
amount of waste that ends up in landfill by transforming it into valuable resources wherever possible.
The Applicant came into being in 2012 when Focsa Services (UK) and Waste Recycling Group (both part of
global infrastructure, environmental services and energy group FCC Citizen Services) came together. The
Applicant employs around 2,400 people across the UK and operates a range of waste management sites
including material recycling facilities, energy from waste plants and landfill sites.
The Applicant is now progressing plans for the Proposed Extension to maximise the benefits of co-location and
use of its existing infrastructure and land holding at Allington, and to further meet the needs for resource recovery
and energy generation.
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1.2 Purpose of the Design Evolution Statement
1.2.1 Introduction
The overall purpose of this DES is to provide information on the principles and approach that have guided the
design evolution process and it:
Sets out the Applicant’s requirements for the design of the Proposed Extension;
Describes how the design has been developed in line with current design guidance;
Demonstrates how the Site and its surroundings have been fully appraised to ensure that the Proposed
Extension is appropriately located and suitably designed;
Identifies the overarching design aims, design objectives and key design considerations which have
influenced the design; and
Describes and explains the design evolution process undertaken.
1.2.2 Planning Policy
The legislative framework for design and access statements is set out at Part 3, s.9 of the Town and Country
Planning (Development Management Procedure) (England) Order 2015 (the GDPO 2015). Such a statement is
not required for a DCO application submitted under the Planning Act 2008, however the Applicant has chosen
to prepare this Design Evolution Statement (DES) in response to policy and guidance requiring more sustainable
and better quality development. This DES illustrates the design evolution associated with the Proposed
Extension and explains the logic underpinning the design decisions taken.
The Overarching National Policy Statement for Energy EN-1 (‘NPS EN-1’) establishes the criteria for good
design for energy infrastructure. At paragraph 4.5.1, it makes the following overarching statement:
“The visual appearance of a building is sometimes considered to be the most important factor in good design.
But high quality and inclusive design goes far beyond aesthetic considerations. The functionality of an object –
be it a building or other type of infrastructure – including fitness for purpose and sustainability, is equally
important. Applying “good design” to energy projects should produce sustainable infrastructure sensitive to
place, efficient in the use of natural resources and energy used in their construction and operation, matched by
an appearance that demonstrates good aesthetic as far as possible. It is acknowledged, however that the nature
of much energy infrastructure development will often limit the extent to which it can contribute to the
enhancement of the quality of the area.”
The National Policy Statement for Renewable Energy Infrastructure (EN-3), taken together with EN-1, provide
the primary basis for decisions on applications it receives for nationally significant renewable energy
infrastructure. At Section 2.4 ‘Criteria for “Good Design” for Energy Infrastructure” it recognises that;
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“Proposals for renewable energy infrastructure should demonstrate good design in respect of landscape and
visual amenity, and in the design of the project to mitigate impacts such as noise and effects on ecology.”
At paragraph 2.5.50 it states that;
“Good design that contributes positively to the character and quality of the area will go some way to mitigate
adverse landscape/visual effects. Development proposals should consider the design of the generating station,
including the materials to be used in the context of the local landscape.”
EN-3 clarifies the use of parameters in DCO projects and how the ‘Rochdale envelope’ works in respect of
detailed design. It states at 2.6.43 that;
“Case law (for example Rochdale MBC Ex. Parte C Tew 1999) provides a legal principle that indicative sketches
and layouts cannot provide the basis for determining applications for EIA development. The “Rochdale
Envelope” is a series of maximum extents of a project for which the significant effects are established. The
detailed design of the project can then vary within this ‘envelope’ without rendering the ES inadequate.”
Given the importance that the Planning Act 2008 places on good design and sustainability, NPS EN-1 paragraph
4.5.3 states that the Secretary of State “needs to be satisfied that energy infrastructure developments are
sustainable and, having regard to regulatory and other constraints, are as attractive, durable and adaptable
(including taking account of natural hazards such as flooding) as they can be”. In so doing, the Secretary of
State should be satisfied that “the applicant has taken into account both functionality (including fitness for
purpose and sustainability) and aesthetics (including its contribution to the quality of the area in which it would
be located) as far as possible”.
It continues, recognising that “whilst the applicant may not have any or very limited choice in the physical
appearance of some energy infrastructure, there may be opportunities for the applicant to demonstrate good
design in terms of siting relative to existing landscape character, landform and vegetation”.
The purpose of this DES is, recognising the priorities within NPS EN-1 and NPS EN-3, to assist the SoS and
others in:
Understanding the Site, its neighbourhood and wider context;
Understanding the process that has led to the chosen design; and
How the proposals have been designed to be attractive, durable, adaptable, functional, and to minimise
visual intrusion.
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1.2.3 Approach to Design Parameters
The approach adopted for the Proposed Extension has accepted that while future flexibility in its design is
required, a level of detail has had to be developed in order to ensure that a robust assessment of the likely
significant environmental effects of the Proposed Extension could be undertaken.
The extent of detailed development has given the Applicant confidence that as a result of the pre-application
design development work there are some aspects of the Proposed Extension that do not require future flexibility
and can therefore be considered fixed. Further information detailing the ‘fixed’ and ‘flexible’ components is
contained within Section 6 of this DES and further detailed within Chapter 5 of the PEIR.
1.2.4 Design Advice
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 considered to be less suited in
assessing the specific design requirements associated with the Proposed Extension. For that reason, it was
decided to refer and draw upon the design guidance offered by the following document.
"A design-led approach to infrastructure": 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 a confident and well
considered architectural design can be achieved. The publication identifies Ten Design Principles which CABE/
Design Council suggest can be used to measure design quality. These are:
Setting the scene
Multi-disciplinary teamwork
The bigger picture
Site masterplan
Landscape and visual impact assessment
Landscape design
Design approach
Materials and detailing
Sustainability
Visitor Centre
How the design of the Proposed Extension has embraced these Design Principles is described in the Design
Guide.
2 The Proposed Extension
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2.1 Overview
The Fourth Line would be constructed on land to the west of the Existing Station, and whilst comprising an
extension to the Existing Station, it is proposed that the Fourth Line would utilise a different thermal treatment
technology to the existing treatment lines. It would include a moving grate combustion system, rather than the
fluidized bed system that operates within the three existing treatment lines, see Chapter 4 of the PEIR for further
details.
The Proposed Extension would complement the Existing Station and include shared infrastructure across the
Site. The illustrative proposed layout is shown on Figure 2.1.
The Proposed Extension does not include the proposed Household Waste Recycling Centre (Proposed HWRC)
which the Applicant is pursuing as a separate development and which is independent from the DCO application.
However, the location and footprint of the Proposed HWRC has had to be taken into consideration in the
development of the design of the Proposed Extension and for that reason is referred to in this DES.
2.2 Key Components of the Proposed Extension
2.2.1 The Fourth Line
The Fourth Line would be divided into several distinct but inter-connected process areas that would largely
mirror the Existing Station. The main spine of the building would be made up of the Tipping Hall, Waste
Bunker, Boiler Hall and Flue Gas Treatment Hall (Fig. 2.2).
The Tipping Hall would be located at the southern end of the building and is where vehicles would reverse into
designated bays, and once the external doors have been closed would tip the residual waste into the Waste
Bunker. From here overhead crane grabs would transfer the waste from the bunker and place it into the high
level hopper which would feed the moving grate located within the Boiler Hall which would sit North of the Waste
Bunker.
The Boiler Hall would represent the highest section of the building and would be where waste is passed along
a moving grate furnace and incinerated. The energy generation process is founded upon hot gases from the
furnace passing to a boiler which converts the energy from the gases into steam. Superheated steam would be
piped from the boilers to a turbine that would generate electricity.
Fig. 2.1 Illustrative Site Layout for PEIR - Extract from PEIR figure 1.6
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The Turbine Hall would be located to the east of the Boiler Hall. The electricity generated would route via
switch gear within the Turbine Hall and then onto a new on-site sub-station and transformers compound. Low
pressure steam exiting the turbine would then be piped to Air Cooled Condensers.
The Air Cooled Condensers (ACCs) would be located to the east of the main building, and is where the steam
would be circulated around a network of pipes that would run above a series of forced draft fans. The air from
the fans would pass over the pipes cooling and condensing the steam into condensate. The condensate would
then be recirculated for use in the boiler system. Gases generated during the combustion process would be
cleaned before being released into the atmosphere.
The Flue Gas Treatment Hall would sit North of the Boiler Hall and would treat the processes exhaust gases
to ensure the plant operates within the emissions limits set by the Industrial Emissions Directive (IED) before
being released to the atmosphere via the Shared Stack.
The Fourth Line would also include (amongst others) a Bottom Ash Hall, Technical Block, Electrical Building,
Fire Water Tank and Pump house, and ammonia and fuel tanks.
Step 1: Residual Waste (waste that cannot be economically or practically re–used or recycled) is delivered to the fourth line extension. This will include capability to process bulky waste using a shredder.
Step 2: From the waste bunker the waste is lifted and fed into a feed chute by overhead cranes.
Step 3: Using proven Energy from Waste moving grate technology, the waste is combusted under controlled conditions at a high temperature to generate heat which is used to raise steam in a boiler.
Step 4: The steam is then used to drive a steam turbine which generates electricity. At this point steam can be extracted to generate hot water to be exported to a district heating network or used for cooling in heat exchangers.
Step 5: Bottom ash is produced from this process. This will be taken off–site for processing.
Step 6: The gases produced by the combustion process are cleaned in the pollution control system using activated carbon and lime and are then filtered before being released into the atmosphere via the single stack shared with the existing facility. The gases from both the proposed extension and the existing three lines are continually monitored as required by the Environment Agency under the Environmental Permit which will regulate the operation of the extension.
Step 7: The residues filtered from the combustion gases are stored in dedicated silos, a specialist treatment facility.
Fig. 2.2 Illustrative Process Flow Diagram
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2.2.2 Shared Infrastructure
The Proposed Extension would also include components which would be shared with the Existing Station (Fig.
2.2).
The Shared Stack would be erected north of the Existing Station and would be shared by both the three
treatment lines of the Existing Station and that from the Fourth line Proposed Extension. The Shared Stack
(chimney) would be in the region of 90m in height above the development platform level and would be
approximately 5.4m in diameter.
The District Heating Centre would be located on the eastern side of the Proposed Extension and would be
where steam from the turbine from the Proposed Extension and the Existing Station would be used to generate
heat and the Site would include all of the necessary infrastructure to enable the heat generated to be supplied
via a potential district heating network to local homes and businesses.
The Existing Station includes existing accommodation, equipment and service infrastructure that would be
shared with the Proposed Extension. This would include its Control Room, Parts Store, and the reagent silos. It
would also include its detached Administration Building/Visitor Facilities located near the entrance to the Site.
The Outage Compound and associated vehicle parking would be located to the west of the Proposed Extension
and would be shared with the Existing Station. This area would also accommodate both permanent and
temporary contactors offices and welfare cabins during planned maintenance outages and provide areas for
laydown of equipment.
The Roads Infrastructure would include new roads systems and vehicle manoeuvring areas around the
Proposed Extension but would also include modification to the existing roads system. The Site’s main entrance
would be shared as would the new Gatehouse and extended weighbridge arrangement.
The Services Infrastructure would include new and shared drainage systems and include an additional
attenuation lagoon to the North West of the Proposed Extension which would be integrated with the existing
drainage and attenuation lagoon. A range of other new and shared services would include lighting; security;
communications etc.
The Sub-Station would be located adjacent to the existing sub-station on the East side of the Existing Station.
Fig. 2.3 Illustrative Connectivity Diagram - Extract from PEIR figure 5.4
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2.2.3 Earthworks
In order to create a level development platform, and to ensure that the Extended 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 undertaken in a phased
manner. Earthworks would generally be undertaken working from south to north over five phases. As a general
rule, topsoil would be stripped and placed on previously completed filling areas to avoid unnecessary double
handling. Where surplus topsoil exists due to minor discrepancy in the size of consecutive phases, it would be
stockpiled separately within a designated temporary stockpile area and managed accordingly. This temporary
stockpile area is located to the south of an existing on-site pond created for surface water management
purposes. The stockpiled topsoil would then be used within the restoration of the next consecutive phase.
The Proposed HWRC development, that would be located within the Site’s existing eastern bund, has been
incorporated into the Extended Station earthworks plan. In the event that the Proposed HWRC is consented and
implemented, the material removed from the Eastern bund to create the Proposed HWRC build platform, which
would be subsequently deposited to the south-west of the Existing Station, would subsequently need to be
transferred to the newly created western perimeter bund as part of the phased earthworks works, and would
then ‘tie-in’ and complete the final proposed landform in preparation for restoration. The movement of the soils
from the Proposed HWRC construction works in this way would then allow the area of the Site originally used
for the disposal of soil from the creation of the Proposed HWRC to be used for the deposit of sub-surface rock
and other material excavated from creation of the Waste Bunker, Bottom Ash Hall and Boiler House.
2.3 Grid Connection
In order to enable the power generated from Fourth Line to be exported to the national grid, a new underground
grid connection (33Kv) is required to the Maidstone substation located on Lenfield Avenue in central Maidstone.
The connection would be undertaken by the District Network Operator (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 to the likely
impacts associated with the installation of the grid connection, and the route that may be taken by the DNO.
Two routes have been considered; the existing route from the Existing Station, running through undeveloped
and suburban areas towards the northern edge of Maidstone (Route A); and an alternative route that follows the
A20, and roads within Maidstone town centre (Route B). For either Route it is anticipated that the grid connection
would be installed via excavating a trench (in a series of short sections). 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. If either route is selected
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it would not be considered likely to give rise to significant environmental effects, however FCC have concluded
that Route B would be preferable because it would offer a more direct route and would give rise to less
environmental impacts.
3 Site Overview
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3.1 Site Location
The Site for the Proposed Extension lies within the County administrative boundary of Kent County Council
(KCC). The location of the Site within its wider context is shown in Figure 1.1. The Site is located within a
former quarry, the vast majority of which is within the administrative boundary of Tonbridge and Malling Borough
Council (TMBC). A small portion of land in the south-western corner lies in the administrative boundary of
Maidstone Borough Council (MBC).
The main Fourth Line building of the Proposed Extension would be sited to the west of the Existing Station,
which is currently operated by Kent Enviropower Limited, a subsidiary of FCC. The extent of the Existing Station
is shown on the existing site layout (Fig 3.1).
The Proposed Extension would add to an already important and strategic site for sustainable energy recovery
and waste management and would make optimal use of a site already in use for waste management and further
increase the capability to recover renewable/low carbon energy. As demonstrated in the CHP Assessment there
are potential local heat demands as identified within the Heat Study in Chapter 5. The co-location of waste
management activities, established roads infrastructure, and local heat demands provide clear and unique
advantages in developing the Proposed Extension at this Site.
3.2 Site Description
The Site’s immediate surroundings and wider context can be summarised as follows:
The M20 Motorway (including slip road associated with Junction 5) is located directly to the north. Beyond
which are open fields, sports fields, offices and industrial units, woodland and a railway line. Further
north beyond the railway line is the River Medway;
Laverstoke Road is located to the east, beyond which is the 20/20 Business Park which includes a range
of commercial uses (including office space, industrial units and distribution units);
St Laurence Avenue is located to the south, beyond which is a mainline railway which is located on a
wooded embankment. Further to the south is a residential development known as ‘The Orchards’, which
forms the northern edge of Allington; and
To the south-west and west is the A20 London Road/Coldharbour Lane beyond which lies Coldharbour
Kent Police Station, a travellers’ site, Poppy Fields Public House, open fields and residential properties
(off East Park Road).
The current context of the Site itself is characterised by two major features.
The first is the Existing Station which together with its ancillary buildings, roads, car parking, access
arrangements, fencing, lighting and drainage infrastructure dominates the eastern portion of the Site.
Fig. 3.1 Existing Site Layout – Extract from PEIR figure 1.2
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The second is the landscaped landform which runs around most of the Site’s perimeter. Rising to a
maximum height of 39m it currently contributes to providing visual and acoustic screening of the Existing
Station from surrounding areas.
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3.2.1 Surrounding Area
Fig. 3.2 Surrounding Area – Photograph Location Plan Fig. 3.6 Site Photograph B – from North Downs Way, Kit's Coty House
Fig. 3.4 Site Photograph D – from A229 footbridge
Fig. 3.3 Site Photograph A – from North Downs Way, Blue Bell Hill
Fig. 3.5 Site Photograph G – Station Road bridge, Aylesford
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Fig. 3.7 Site Photograph K – from A20 London Road, near M20 junction Fig. 3.8 Site Photograph C – from Medway Valley Walk, M20 footbridge
Fig. 3.10 Site Photograph E – from Allington Sports Ground Fig. 3.9 Site Photograph F – from B2246, Hermitage Road
Fig. 3.11 Site Photograph J – from A20 London Road, near police station Fig. 3.12 Site Photograph I – from Laverstoke Rd, opp Site entrance
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3.2.2 Site Opportunities and Constraints
Fig. 3.13 Site Analysis and Site Photographs Locations
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3.2.3 Site Photographs
Fig. 3.17 Site Photograph 4 – Existing Gatehouse complex Fig. 3.16 Site Photograph 3 – Existing Station from SW Fig. 3.18 Site Photograph 5 – Existing Station from SE
Fig. 3.14 Site Photograph 1 - Existing Station from NE Fig. 3.15 Site Photograph 2 - Existing Station Stack & FGT
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3.3 Site History
A detailed history of the Site can be found in Chapter 5 within the PEIR.
Prior to the commencement of quarrying operations, the Site was formerly occupied by farmland and included
country roads and farmhouses.
In the late 19th Century quarrying operations commenced along the northern edge of the Site and in the first half
of the 20th Century the ‘Aylesford Quarry’ expanded south into the area directly adjacent to the north of the
Existing Station.
In the second half of the 20th Century the renamed ‘Allington Quarry’ expanded into the eastern and central
areas of the Site. It continued to increase in size westwards and ultimately encompassed the majority of the
Site. In 1995 the Site was granted a landfill permit and inert landfilling operations commenced.
In the 1990s, KCC adopted a waste strategy that demonstrated the key aim of reducing the County’s reliance
upon landfill, as landfills in the County had filled up rapidly and waste was being hauled by trucks to Essex for
disposal. This did not prove to be a sustainable solution, and in response a project was developed to reuse the
Allington Quarry as the home for a new sustainable waste management facility. In the year 2000, KCC granted
Kent Enviropower planning permission for the Existing Station.
Following the closure of landfilling operations, part of the inert landfilled waste was excavated from the east of
the Site and deposited on the western part of the Site to form a large screen bund, and in so doing cleared the
basin of the old quarry for construction of the Existing Station.
During 2005 and 2006, the landfilled area was restored to grassland and woodland, and the Existing Station
became operational in late 2008.
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3.4 Site Analysis
3.4.1 The Site
The site is already historically industrialised in terms of character and appearance with the Existing Station being
located within the eastern half of the Site. However, the overall extent of the Applicant’s landholding and the
area covered by the current planning consent extends further to the west up to Coldharbour Lane.
The Existing Station is located at the base of the former ragstone quarry and is surrounded by earth mounds
which have been planted with trees and shrubs as part of the landscape restoration scheme. As a consequence,
the Existing Station is largely screened in views from outside of the Site, with the exception of the stack.
The Existing Station comprises several distinct but inter-connected process areas within its main single building
which contains the Energy from Waste (EfW) facility. In addition, there is a range of external plant and subsidiary
buildings including an 80m high stack which would be replaced as part of the Proposed Extension.
The Existing Station and associated infrastructure are surrounded by areas of hardstanding and internal
circulation roads, and the Site is secured by 2.4m high palisade fencing and matching gates.
The layout and arrangement of the Existing Station is shown on Figure 3.19.
There are a number of advantages and opportunities in locating the Proposed Extension on this site:
It expands the existing onsite waste management use and in so doing provides additional sustainable
waste management capacity helping to drive waste management up the waste hierarchy and diverting
residual waste away from landfill. As a consequence, it avoids methane emissions from landfill disposal;
It provides the opportunity to deal with RDF that would otherwise be exported to the continent thereby
significantly reducing the greenhouse gas emissions resulting from transporting waste abroad;
It allows for the recovery of energy, the majority of which would be classified as renewable, thereby
reducing the reliance on fossil fuels and helping to ensure the UK has safe, secure and affordable energy;
It creates the opportunity to provide direct heat and power to major development sites located within a
growth area of the UK;
It avoids the need for the development of waste management facilities elsewhere in less appropriate and
less sustainable locations;
The sharing of existing and new infrastructure with the Existing Station minimises the extent of the
proposed development and offers improvements in efficiency; and
Existing road/footpath network would be used for access requirements.
Fig. 3.19 Existing Station Layout – Extract from PEIR figure 1.2
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There are also a number of factors that have been, and would continue to be, addressed as the design
progresses: -
Ensuring that operations at the Existing Station would remain ongoing during construction of the
Proposed Extension;
Mitigating the potential impacts of the Proposed Extension (i.e. visual; noise);
Integration with and the improvement of the existing internal roads system within the Site; and
Integration with and the improvement of the existing services infrastructure within the Site.
3.4.2 Access
The Proposed Extension and Existing Station would share the existing access from Laverstoke Road which
connects to St Laurence Avenue via a priority junction which in turn connects to the A20 via a roundabout. The
A20 London Road / Coldharbour Lane provides a direct connection to Junction 5 of the M20.
Both Laverstoke Road and St Laurence Avenue include a shared cycle / pedestrian footpath which provide
access to the Site and the wider 20/20 Business Park.
The existing access arrangement would be improved to allow for the free flow of commercial and private vehicles
internally within the Site. It would allow HGVs to access the Proposed Extension and the Existing Station
independently and would provide for additional internal queuing capacity.
The Proposed Extension would include:
vehicular access for waste vehicles, employees and visitors etc.;
parking spaces for cars and motorcycles;
pedestrian and cycle access;
covered cycle stands; and
a contractors’ parking and laydown area.
The Proposed Extension would be designed to comply with the requirements of the Inclusive Access and
Equality Act 2010 and a full access strategy would be developed during the development of the detailed design.
4 Design Principles
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4.1 Overview of the Design Principles to Date
This Design Evolution Statement and its accompanying Design Guide have been developed as part of the pre-
application design development process.
The Design Evolution Statement provides a summary of the design evolution of the Proposed Extension and
highlights the key decisions that have been taken through the design process. It identifies those components
which have achieved a fixed design. It also details those components that will require future design flexibility
and includes the maximum parameters within which they would be developed and upon which the environmental
assessments have been based.
The Design Guide describes how using the fixed and flexible design components established within the DES
might be developed within the given parameters. It includes an illustrative design of how the final design might
be realised, and this has informed the development of a series of Design Codes which will be used to guide the
completion of the design.
Following granting of the DCO the design evolution process would continue and once the detailed design of the
flexible design components is finalised they will be submitted to the Local Planning Authority for approval.
4.2 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.
A key consideration has been the selection and configuration of the Fourth Line’s internal technology. While the
Proposed Extension is an extension to the Existing Station, the proposed Fourth Line would utilise a different
thermal treatment technology to that of the Existing Station. Alternative horizontal and vertical arrangements for
this technology were considered, and this exercise concluded that a horizontal arrangement would have to be
adopted in order to minimise the overall height of the Fourth Line main building. This decision also determined
the footprints upon which the development of the early layout studies was based.
Having selected the technology and its configuration the design development studies were commenced and a
range of design principles have been used to inform that design process.
The principal design objectives have been to:
Minimise the scale of the main Fourth Line building by adopting a ‘form follows function’ design approach
and avoiding more ‘sculptural’ designs which would stray from being volumetrically efficient;
Due to the process technology, the Proposed Extension would be taller than the Existing Station, and to
minimise its visual impact, careful consideration would need to be given to determining the levels of the
development platforms to best utilise the screening benefits of the existing and modified perimeter
landform;
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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 Extension design
and these included:
Minimising the Fourth Line main building footprint;
Minimising where possible the individual building sizes (heights and volumes);
Establishing a logical and efficient process arrangement in the layout of the main process 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 providing 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.
5 Design Evolution
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5.1 Introduction
The development of the Proposed Extension has been informed by a number of factors. This has included
working with the constraints and opportunities offered by the Site; meeting the stated design principles; ensuring
an operationally efficient state of the art energy recovery facility; optimising connectivity with the Existing Station;
and considering how to best mitigate the development’s impact within its setting.
As part of the design evolution process a range of alternative illustrative site layout studies were developed to
explore the potential distribution and orientation of the various process functions, but also to consider shared
infrastructure with the Existing Station, and to establish access and circulation strategies to ensure efficient and
safe traffic movements within the Site.
The arrangement of the Proposed Extension is dictated by the sequence of process spaces it houses and for
the initial layouts certain assumptions on footprint areas were taken from other reference facilities, and the area
available for the development is such that the preferred linear arrangement of these spaces could be adopted.
These early studies also tested alternative layouts for the location of the administration building and related car
parking as well as servicing and potential drive through arrangements.
The access to the Site determined that the Tipping Hall would have to be located at the southern end of the
Fourth Line main building as this was the only arrangement that allowed the required connectivity with the
existing access and weighbridge arrangements.
In accordance with the principles of the Rochdale Envelope maximum parameters have been applied to the
unfixed design components of the Proposed Extension to enable a worst case assessment to be undertaken.
Further detail on how the Rochdale Envelope has been applied can be found in Chapter 6 of the PEIR and the
final design will be completed under a set of Design Codes which would cover the following matters:
Location, Massing and Form of the Fourth Line;
Architectural Design
Materials;
Colour;
Integrated Biodiversity and Landscaping; and
Lighting.
Detail on the Design Codes can be found within the Design Guide.
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5.2 Illustrative Site Layout
5.2.1 Initial Layout Studies
This stage of design focussed on the location and orientation of the main components and their relationship with
the Existing Station, rather than the consideration of their detailed infrastructure. At this time an Anaerobic
Digestion (AD) facility formed part of the proposals, and it was considered that it would be best located alongside
the main building. As previously mentioned the proposed HWRC does not form part of the Proposed Extension,
however its potential development did have to be considered in developing early design studies, and at the time
of preparing the initial layout studies the Proposed HWRC was potentially being located to the south of the
existing access arrangement.
Layout 1 (Fig. 5.1) orientated the extension proposals in an east/west orientation with the stack at the western end of the site, and the AD facility to its north.
Advantages
The linear arrangement of the internal processes mirrored that of the Existing Station;
Located the tipping hall close to the site entrance and gatehouse and weighbridge arrangement;
Maintained sufficient stand off from the southern boundary to retain substantial landform screening.
Disadvantages
Layout presented a detached architectural arrangement with the Existing Station
The plan configuration reduced the opportunities to share components with the Existing Station (i.e.
stack; roads, drainage infrastructure etc.);
Noise generating components (ACC) located close to the nearest receptor to the south of the Site.
Layout 2 (Fig. 5.2) orientated the extension proposals north/south with its stack at the northern end of the site.
Advantages
Layout provided a balanced architectural arrangement with the Existing Station;
The linear arrangement of the internal processes mirrored that of the Existing Station;
Minimised the overall development footprint;
Located the Tipping Hall close to the site entrance and gatehouse and weighbridge arrangement;
Noise generating components (ACC) located far away from the nearest receptor to the south of the Site;
Maintained sufficient stand off from the southern boundary to retain substantial landform screening.
Disadvantages
Alignment with the Existing Station staggered.
The two options were reviewed with regard to landscape and visual effects and this concluded that there would
be little difference between either, as both were likely to give rise to relatively limited and localised effects due
Fig. 5.1 Initial Layout 1
Fig. 5.2 Initial Layout 2
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to the screening provided by the existing landform and vegetation around the Site perimeter. The Appraisal also
identified that a key consideration in limiting adverse effects would be the approach taken to design and phasing
of earthworks remodelling, and the associated effects upon the retention of mature tree cover.
5.2.2 Developed Layouts
The previous stage of design development concluded that a north/south alignment would be the optimum
orientation for the extension proposals as it was considered to offer the best balance between operational
requirements, the constraints of the Site, and mitigating anticipated visual and landscape effects.
Further assessment was undertaken into determining the footprint sizes required for the components making
up the extension and from these an updated masterplan was developed. Layout 3 (Fig. 5.3) orientated the
extension proposals in a north/south orientation with the stack at the northern end of the Site and incorporated
the following updates:
A shared contractor’s parking area located to the north of the extension proposals alongside a drainage
attenuation lagoon;
The Anaerobic Digestion facility on the western side of the extension proposals and which would share
its roads infrastructure;
The linear arrangement of the internal processes mirrored that of the Existing Station;
A weighbridge arrangement segregated from that serving the Existing Station;
The Proposed HWRC moved further west to sit south of the extension proposals in order to allow for the
creation of a longer queuing lane for residents using the Proposed HWRC, and to enable the design of
a more efficient operating roundabout at the existing site access .
The layout and surrounding infrastructure associated with the main building had undergone further design
development and included:
A one way clockwise perimeter roads system which provides access to staff and visitor car parking on
the west side of the building adjacent to the office and welfare accommodation;
Ash collection and other service access on its eastern side;
The Turbine Hall and ACC were located on the north western corner of the building;
A sub-station between the main building and the AD facility.
In principle the overall arrangement ‘mirrored’ the layout of the Existing Station and established a focus for
operational activities between the two on the eastern face for the extension proposals.
The final stages of the developed layout studies resulted in Layout 4 (Fig. 5.4) which incorporated:
Fig. 5.3 Developed Layout 3
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Alterations to the contractor’s parking compound;
Relocation of the surface water attenuation lagoon to allow for a larger and more efficient contractors parking
arrangement;
The addition of a District Heating Centre to the north of the Proposed Extension;
Adjustments to the perimeter roads infrastructure to better segregate HGV and cars;
Expansion and modification of the proposed weighbridges arrangement and associated roads infrastructure
for the extension proposals to address concerns over potential HGV queuing impacting upon the operations
of the Existing Station.
Fig. 5.4 Developed Layout 4
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5.2.3 Refined Layouts
Following a decision by KCC to look at alternative locations for an AD facility within Kent there was no further
need for an AD facility to form part of the development proposals, and its removal allowed for the contractor’s
compound to be expanded to include laydown areas for equipment and temporary storage during outages. The
layout had to be revisited to reflect this but also to improve car/HGV segregation and traffic flow patterns around
the Site and between that serving the Proposed Extension and the Existing Station. The updated Layout 5 (Fig.
5.5) included the following updates:
Anaerobic Digestion proposal removed and replaced with Contractor’s Laydown area;
Main access and entrance roundabout revisited, and an alternative more compact design arrangement
adopted to leave the northern road/car park and the north east kerb line and footpaths as existing;
Staff car park segregated from perimeter HGV roads system;
Improved segregation between outbound and inbound accessing the Existing Station;
Improved segregation of inbound and outbound traffic flows serving the extension proposals;
Adjustments to the development platform levels and detail development of vehicle ramps between the
different platform levels.
The next stage of design sought to refine the site layout to further develop connectivity with the Existing Station
and the vehicle flows around the Site, and the building’s footprint requirements were also updated. As a result
the updated Layout 6 (Fig. 5.6) incorporated a number of fundamental changes including:
The Fourth Line main building plan was updated and mirrored around its north/south axis and moved
further north on the Site to better align its northern extents with that of the Existing Station;
To make way for the northwards movement of the Fourth Line main building the shared contractor’s car
parking area was relocated to the west of the extension proposals to form an enlarged shared Outage
Compound with the contractor’s laydown area, and the District Heating Centre relocated to the eastern
side of the Fourth Line main building to improve shared connectivity; and
In response to the above changes the location and shape of the attenuation lagoon was adjusted to
make more efficient use of the Site and better relate to the base of the perimeter landform.
The changes offered a range of improvements including:
Improved connectivity between the Existing Station and the extension proposals;
Allowed the Proposed Extension to share (via pipe bridge) a new Shared Stack with the Existing Station
as being located adjacent to the Existing Station’s stack removed the need for a separate stack to serve
the Proposed Extension;
Allowed the District Heating Centre to be centred between the Existing Station and extension proposals
for shared use;
Fig. 5.5 Refined Layout 5
Fig. 5.6 Refined Layout 6
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Enabled the extension proposals to share (via pipe bridge) the silos of the Existing Station;
Relocated the sub-station to be adjacent to the existing sub-station located to the east of the Existing
Station;
Moved the Fourth Line main building away from the Site’s southern boundary thereby reducing the extent
of modification required to the landform bunding and assisting in reducing noise impact to southern
receptors;
Located the Turbine Hall and ACC on the eastern side such that they would be better acoustically
screened by the Fourth Line main building from nearby sensitive receptors to the south west of the Site;
Lowered the northern platform level for the Proposed Extension from +20 AOD to +16 AOD which aligned
the levels with the Existing Station at the northern end of the Site which had several benefits, not least
the overall lowering of the building visually but also in improving operational connectivity;
Lowered the manoeuvring apron to the Tipping Hall from +20 AOD to +18 AOD – this set it as an
intermediate platform between the +20 site entrance level and the +16 AOD building level and reduced
the extent of excavation and vehicle ramp lengths between the southern and northern area of the Site.
This also reduced the excavation required for the Waste Bunker due to the higher level of the Tipping
Hall and assisted with reducing noise due to the screening benefit from the existing earth mounding to
the south;
Rationalised the roads infrastructure and the associated ramps to access the different platform levels.
Having established a developed site layout a series of reviews were held with the site based FCC operations
team to consider how the layouts might be further refined to improve integration with the existing traffic patterns
on the Site. A range of studies of alternative vehicle tracking patterns were carried out (Fig. 5.8). This was a
very productive exercise and one which allowed the roads infrastructure to be adjusted to better reflect the day
to day requirements of the ongoing and future operations of the Existing Station as well as that of the extension
proposals.
The main changes that resulted from this stage of design focussed on the access control and weighbridge
arrangement and the traffic routeing for cars and HGVs to maximise their segregation and to avoid congestion
at the Site’s main HGV entrance.
Layout 7 shown in Figure 5.8 included the following updates:
The Gatehouse/Weighbridge arrangement was rationalised and moved further west into the Site to
increase queuing capacity to avoid congestion on the entrance roundabout;
The new arrangement when combined with variable overhead directional signage would ensure optimal
segregation of the Existing Station and the Proposed Extension’s HGV routeing around the Site;
The southern site access via the weighbridge gatehouse would be dedicated to HGV and other service
traffic to ensure efficient operations of this arrangement;
Fig. 5.7 Layout 6 - Connectivity Diagram
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Cars accessing the Site would use the existing northern spur from the entrance roundabout. This would
segregate them from the HGVs and weighbridge arrangement and would allow them to enter via the
current security-controlled gate operated form the existing administration building on the east side of the
Existing Station;
On passing security, cars would either access the updated existing staff car park to the east of the
Existing Station or use a widened two-way road around the north of the Existing Station to access the
car park for the Proposed Extension. Exit from the Site would follow the same route.
Fig. 5.8 Layout 7 - Vehicle Tracking Diagram
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5.2.4 Final Illustrative Layout for PEIR
Following a technical review with a technology supplier a final iteration of the layout was undertaken and this
incorporated a number of changes to the plan arrangement of the main process building to better fit the
technology requirements and to improve operational efficiency (Fig. 5.9). The changes to the design included:
An overall reduction in footprint area of the FGT Hall; the Admin/Technical Block; and the Tipping Hall;
A slight increase in the footprint area of the Workshop and Bottom Ash areas;
The reconfiguration of the ACC layout and an increase from 4 no. to 6 no. cells to improve efficiency;
The previously proposed excavation for the FGT was omitted;
A number of revisions to the smaller components of external equipment/plant.
The resulting final Proposed Extension design is illustrated in Figure 5.10.The development of the final iteration
of the Proposed Extension offers one illustrative approach on how it might be arranged on the Site and includes
the following components:
The location and footprint of the Fourth Line main building;
The location and footprints of those ancillary components which will be covered by design parameters
in order to ensure flexibility in their future design development;
The range of components to be shared with the Existing Station include:
- Shared Stack and associated emissions monitoring systems;
- a shared district heating centre;
- a shared outage compound with associated contractor parking and permanent and temporary
cabins;
- a shared access from the public highway and part shared internal access arrangement;
- a shared new gatehouse and weighbridge arrangement from the existing access off
Laverstoke Road;
- a shared extended sub-station next to the existing staff car park; and
- new roads and vehicle circulation areas.
Fig. 5.9 Final update – Process Areas Adjustments
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Fig. 5.10 Illustrative Site Layout for PEIR – Extract from PEIR figure 1.6
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5.3 Building Massing
5.3.1 Initial Massing Study
In parallel with developing the site layout designs the architectural design of the Fourth Line main building was
being developed in outline both 2D and 3D CAD in order to assess how best to mitigate its impact and how it
might relate to the Existing Station (Fig 5.12 & 5.13).
While comprising an extension to the Existing Station, the proposed Fourth Line would utilise a different thermal
treatment technology to the Existing Station. This determined the footprints upon which the development of the
early layout studies was based, but it also generated a different sectional profile to that of the Existing Station.
Therefore a key principle was the need to ensure that the highest roof areas of the Fourth Line main building
were kept as low as possible to best mitigate its visual impact, but also utilise its lower roof plates to allow the
main building’s profile to step down and be more in keeping with the scale of the Existing Station.
In order to achieve this, alternative horizontal and vertical arrangements for the boiler were tested and it was
concluded that a horizontal arrangement would best achieve the lowest overall height. Furthermore it was
decided that the floor level of the Boiler Hall would have to be dropped approx. 18m below ground level, and
that also a large part of the FGT Hall would need to be lowered by 5m below ground level to minimise its overall
height (Fig. 5.11).
As an extension it is important to replicate some of the architectural features of the Existing Station in order to
establish a ‘family of buildings’ on the Site. While many of these features would be categorised as design
parameters of the building in order to retain flexibility for future design development, the design of some features
could be developed. This included incorporating the following architectural features:
Adopting a ‘form follows function’ design approach in order to minimise the overall scale of the building,
and be in keeping with the Existing Station by being volumetrically efficient;
Adopt refined and visually clean cubic forms which step down and interlock with each other to form the
building’s overall massing/shape; and
Incorporating sweeping shallow curved roof plates with oversailing eaves to keep the height of the
building as low as possible and below the sight lines of the earth bund surrounds, but also to soften it
visually and to add visual interest.
Fig. 5.11 Initial Massing Study - Longitudinal Section
Fig. 5.13 Initial Massing Study – Aerial View
Fig. 5.12 Initial Massing Study – Eye Level Views
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5.3.2 Developed Massing Study
The architectural design of the Proposed Extension was revisited in order to reflect the revised arrangement
and location being determined by the layout design work. Again, this was developed in both 2D and 3D (Fig.
5.14) and the design principles to repeat a similar design approach to that of the Existing Station was adopted.
This included the use of sweeping curved roof forms and refined ‘form follows function’ cubic forms for the main
Fourth Line main building.
One of the other design developments was that following further technical review the section profile through the
Fourth Line main building was adjusted to reflect a small reduction in the height of the boiler. This resulted in a
reduction in the below ground level of the floor of the Boiler Hall which was then raised from -18m to -16.8m and
the previous -5m drop in part of the FGT Hall floor was also removed as this was no longer required (Fig 5.15).
Reviewing the updated design, it was clear that the layout changes and the relocation of the main building made
in Layout 6 (Fig. 5.16) had improved its relationship with the Existing Station.
Fig. 5.14 Developed Massing Study – Eye Level View from the south east
Fig. 5.15 Developed Massing Study – Longitudinal Section
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Fig. 5.16 Developed Massing Study – Aerial View from the north east with Existing Station shown in the foreground
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5.4 Landscape and Ecology
5.4.1 Landscape
The landscape proposals for the Proposed Extension (Fig 5.17) 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.
5.4.2 Ecology
The construction of the Proposed Extension requires the current development platform to extend west into the
existing Nature Conservation Area (NCA). The NCA does not benefit from any statutory or non-statutory status;
however, a commitment was made within the Section 106 to which the Existing Station’s planning permission is
required to retain the NCA in its current state. The result of the Proposed Extension is that the NCA will be lost
in its entirety, albeit following completion of the earthworks and construction works, part of the site formally
identified as the NCA would be restored and landscaped as illustrated in the proposed soft landscaping (Fig.
5.17). The landscape scheme has been developed with the aim of maximising the on-site biodiversity and
landscape benefits by providing a scheme which broadens the scope of ecology across the remaining area,
increases native planting which would improve the quality of screening and importantly seeks to deliver public
access to the restored landscaped areas through a network of permissive public footpaths.
Chapter 11.0 (Ecology and Biodiversity) has concluded that the removal of the NCA would result in limited
biodiversity harm, albeit not significant in EIA terms. This is irrespective of the fact that the land that remains
following construction of the Proposed Extension can be restored to a high level and provide opportunities for
improved nature conservation. To quantify that loss, when compared with the proposed restoration and
landscaping, an assessment has been carried out using the Natural England Biodiversity Metric (BM2.0).
Whilst not necessary in order to make the proposals at Allington acceptable, the Applicant is keen to ensure that
any proposal at the Site ultimately delivers net gain in terms of biodiversity. The Applicant recognises that an
opportunity exists to provide additional compensatory habitat off-site to achieve the net gain they ultimately wish
to deliver.
The Applicant has identified a site under their ownership located within the same District as the Allington Site,
known as the former Stangate landfill near Borough Green, at which biodiversity enhancements can be
delivered. Therefore, in addition to the improved landscape restoration scheme at the Allington site, they are
Page | 36
proposing the submission of an application for planning permission at Stangate that will deliver an improved
final landform and increased biodiversity (the Stangate Ecological Enhancement Scheme). The extent and value
of the biodiversity benefits that would be delivered at Stangate have been quantified using BM2.0. In the event
that planning permission cannot be secured, the Applicant is committing an alternative scheme at Stangate that
does not require express planning consent. The Applicant is committed to delivering one or other of the Stangate
Ecological Enhancement Schemes through a new Section 106 agreement or undertaking.
Fig. 5.17 Illustrative Landscape Masterplan - Extract from PEIR figure 9.6b
6 Design Parameters
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6.1 Introduction
While flexibility in design is required, a level of detail appropriate to the submitted application has been set out,
assessed and presented within the PEIR, in order that a robust assessment of the likely significant environmental
effects of the Proposed Extension could be undertaken.
Furthermore while design flexibility is required, the design development process has been steered throughout
by the FCC technical team who themselves have regularly sought input from energy from waste technology
providers to ensure that the major components making up the Proposed Extension are adequately sized and
essentially fixed. Therefore, in relation to Design Parameters the Proposed Extension can be broken down into
two categories:
Fixed Design - those components that have been fixed in their footprint, height and location; &
Design Parameters – those components where it has not been possible to fix at this stage and where future
flexibility in their size is required to allow for changes in technology and process requirements during the design
process.
6.2 ‘Fixed’ Design
There are a 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 main Fourth Line process building and includes the following components:
Tipping Hall;
Bunker;
Boiler Hall;
Flue Gas Treatment Hall;
Turbine Hall;
Bottom Ash Storage and Collection bay;
Electrical Rooms;
Workshops;
Technical Block (inc. offices; welfare & Crane Control Room.)
These components are recorded in a series of drawings (Fig. 6.1; 6.2; 6.3; & 6.4) which define the fixed massing
of the Fourth Line in terms of footprint; height; roof forms and their spatial relationships in forming the Fourth
Line.
The location of the Fourth Line main building on the Site is also fixed as are the AOD levels of its development
platforms.
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Fig. 6.4 Fourth Line - ‘Fixed‘ Massing – West Elevation – Extract from PEIR figure 5.6d Fig. 6.3 Fourth Line - ‘Fixed‘ Massing – South Elevation – Extract from PEIR figure 5.6c
Fig. 6.1 Fourth Line - ‘Fixed‘ Massing – North Elevation – Extract from PEIR figure 5.6a Fig. 6.2 Fourth Line - ‘Fixed‘ Massing – East Elevation – Extract from PEIR figure 5.6b
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6.3 Design Parameters
Through the design development work a number of design parameters have been identified and cover those
components of the Proposed Extension, including the relocated screen bank, but specifically for the Proposed
Extension where flexibility needs to be retained for future design development. In all cases they are defined by
the anticipated ‘worse case’ dimensional parameters. However, where they relate to the larger scale
components of the Proposed Extension the design parameters have been further refined to minimise the scope
of flexibility being sought in recognition of the sensitivities of their potential scale and form. In all instances it is
these ‘worse case’ parameters that have then been taken into consideration in the assessments undertaken in
the EIA.
The design parameters fall into three categories.
6.3.1 Works Plan
The Works Plan document identifies the range of works required to deliver the Proposed Extension into a series
of Work packages the design of which will be completed as part of the DCO. The work packages comprise the
following:
Work No. 1 — Works to construct an Extended Station including:
1A - An extended station (and defined as being fixed in footprint and scale in Section 6.2);
1B - A series of buildings with and without roof enclosing and/or supporting all or part of Work Nos. 1A;
1C - Works to address the interface elements between the Existing Station and the Proposed Extension;
1D - Infrastructure and utilities supporting the development and functioning of all or part of the elements
described in 1A, 1B and 1C.
Work No. 2 Weighbridge Infrastructure
Work No. 3 Earthworks
Work No. 4 Works to construct and install combined heat and power equipment
Work No. 5 Works to construct temporary construction compounds and permanent shutdown maintenance
offices and associated parking
Work No. 6 Works to extend the existing substation and electrical housing as detailed for all electrical
underground cables and associated telemetry
Work No. 7 Shared Stack including associated equipment works, structures, ducting and platforms
Work No. 8 In connection with and in addition to Work Nos. 1 – 7 and, to the extent that it does not otherwise
form part of those Work Nos.
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The design parameters covering the above Work No. items are illustrated on the Works Plan site layout (Fig.
6.5) which defines their maximum extents across the Site and in their relationship to each other.
Fig. 6.5 Proposed Extension - Works Plan – Extract from PEIR figure 5.13
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6.3.2 Design Parameters Table
The Design Parameters Table included below (Fig. 6.6) covers the main Works Packages and in recognition of
the sensitivities of their potential scale and form, details the maximum heights and scope of flexibility being
sought for each.
PROPOSED EXTENSION ‐ PARAMETERS TABLE
Proposed Extension
Work Plan
Description Item Maximum number
Maximum height (metres)
Maximum height (AOD)
1A
An Extended Station (and defined as being fixed in footprint and scale)
Fixed Massing n/a 37.00m 53.00m
(AOD)
Rooftop equipment
(Boiler Hall roof)
n/a 43.77m 59.77
(AOD)
Rooftop equipment
(intermediate roofs)
n/a 33.50m 49.50m
(AOD)
Rooftop equipment
(lower roof)
n/a 17.70m 33.70m
(AOD)
1B A series of buildings with and without roof enclosing and/or supporting all or part of Work Nos. 1A
Air cooling system comprising air‐cooled condensers and all ancillary pipework and pipe bridges
6 24.00m 40.00m
(AOD)
Diesel and ammonia storage tanks including all necessary bunding structures, pumping and distribution equipment
1 + 1 8.00m 24.00m
(AOD)
Fire water tank, pump room(s) and fire protection facilities
1 + 1 13.70m 31.70m
(AOD)
Foundations and underground substructure to support the buildings, platforms, bunding structures, tanks and the enclosing building(s) structures and finishes
Various n/a n/a
1C Works to address the interface elements between the Existing Station and Proposed Extension
All Various 11.00m 27.00m
(AOD)
1D Infrastructure and utilities supporting the development and functioning of all or part of the
All Various n/a n/a
Page | 42
elements described in 1A, 1B and 1C
2 Weighbridge Infrastructure All Various 8.00m
30.00m
(AOD)
3 Earthworks
All
Various n/a 42m
(AOD)
4 Works to construct and install combined heat and power equipment
All
1 18.00m 34.00m
(AOD)
5 Works to construct temporary construction compounds and permanent shutdown maintenance offices and associated parking
5A ‐ Temporary works Various n/a n/a
5B ‐ Permanent works Various 14.00m 32.00m
(AOD)
6 Substation Works to extend the existing substation and electrical housing as detailed for all electrical underground cables and associated telemetry
Various 9.00m 25.00m
(AOD)
7 Extended Station Shared Stack 7A ‐ Emission stack inc. surrounding wind shield and maintenance access ladder
1 90.00m 106.00m
(AOD)
7B ‐ CEMS platform and connecting ducting and support structures to existing station
Various 44.00m 60.00m
(AOD)
8 Additional Works In connection with and in addition to Work Nos. 1 – 7 and, to the extent that it does not otherwise form part of those Work Nos., further associated development
Various n/a n/a
Fig. 6.6 Parameters Table
Page | 43
6.3.2 Illustrative Parameters Drawings
In order to visually communicate the extent of flexibility defined within the Design Parameters Table an illustrative
Parameters of Deviation site plan (Fig. 6.7) and illustrative Parameters of Deviation elevation drawings (Figs 6.8
to 6.12) have been developed to cover the main components of the Proposed Extension. This includes:
Air Cooled Condensers;
Rooftop equipment (inc. vents);
Fire Water Tank and Pump House;
Pipe Bridges;
Shared Stack (inc. the Shared Stack itself; ladder; CEMS platform; ductwork alterations from the Existing
Station);
Substation and switchyard;
Earthworks to adjust landform.
The design parameters table covers the key elements of the Proposed Extension and where the principle of the
Rochdale Envelope has been applied. Smaller process elements required for the function of Proposed Extension
and the detail design of the building envelope of the Fourth Line would be designed in accordance with the
Design Codes detailed within the Design Guide.
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Fig. 6.7 Illustrative Parameters of Deviation – Extract from PEIR figure 5.12a
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Fig. 6.8 Illustrative North Elevation – Parameters of Deviation – Extract from PEIR figure 5.12b
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Fig. 6.9 Illustrative East Elevation – Parameters of Deviation – Extract from PEIR figure 5.12c
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Fig. 6.10 Illustrative South Elevation – Parameters of Deviation – Extract from PEIR figure 5.12d
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Fig. 6.11 Illustrative West Elevation – Parameters of Deviation – Extract from PEIR figure 5.12e
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Fig. 6.12 Illustrative East Elevation (inc. substation) – Parameters of Deviation – Extract from PEIR figure 5.12f
7 Conclusion
Page | 50
This Design Evolution Statement (DES) has been prepared to explain how the design of the Proposed Extension
has been developed and highlights the key decisions that have been considered through the design process.
The evolution of the design has been informed by the opportunities and constraints offered by the site and its
surroundings. The illustrative design of the Proposed Extension is appropriately located and designed to best
mitigate its visual and other impacts has been developed in line with current design guidance. The relationship
with the Existing Station has also been carefully considered with shared functions and infrastructure optimised
to create an Extended Station.
The early involvement by FCC of a process technology supplier has allowed a range of components making up
the Fourth Line main building to be fixed in terms of their overall massing and form.
The principle of the Rochdale Envelope has been applied to those components where future design flexibility is
required and defining these components by a set of worse case Design Parameters ensures that the likely
significant effects of the Proposed Extension have been robustly assessed.
Future detailed design development of the Proposed Extension will be guided by the Design Guide. This
separate document describes how the fixed and flexible design components established within the DES might
be developed within the given Design Parameters. It also includes an illustrative design of how the final design
might be realised, and this has informed the development of a series of Design Codes which will be used to
guide the completion of the detailed design to ensure it will be appropriately designed to further mitigate its
visual impact and to relate it architecturally with the Existing Station.
It is considered that overall the design of the Proposed Extension is well-considered and has been developed
in accordance with current design guidance applicable to energy infrastructure development and offers an
appropriate design in line with the policies set out in the relevant National Policy Statements.
