The Corfe Mullen to Salisbury Transfer Environmental ......The Corfe Mullen to Salisbury Transfer...

The Corfe Mullen to Salisbury Transfer Scheme

5096140/Volume 1 - Non Technical Summary - FINAL 1


Environmental Statement, Volume I Non-Technical Summary

November 2012

Notice

This document and its contents have been prepared and are intended solely for Wessex Water’s information and use in relation to The Corfe Mullen to Salisbury Transfer Scheme.

Atkins Limited assumes no responsibility to any other party in respect of or arising out of or in connection

with this document and/or its contents.



Contents

Section Page

Introduction 5

Why is the Scheme Needed? 5

The Proposed Scheme 7

Description of Development 12

Environmental Impact Assessment Methodology 16

Planning Context 17

Ecology and Nature Conservation 18

Historic Environment 21

Landscape 22

Water Environment 24

Traffic and Transport 25

Noise and Vibration 26

Air Quality 27

Miscellaneous and Cumulative Impacts 28

Conclusions 29

List of Figures

Figure 1 - The Corfe Mullen to Salisbury Transfer Scheme 6

Figure 2 - Illustration of the key issues that will be resolved by the Scheme 7

Figure 3 - Options Identification and Assessment Process 8

Figure 4 - Illustration of the ‘long list’ alternatives and the two chosen ‘short-list’ alternatives 9 Figure 5 - Map of the Scheme showing route and Local Planning Authority boundaries 11

Figure 6 - Illustration of an example of a large pumping station, once constructed 12

Figure 7 - Illustration of a typical storage tank, once constructed 13 Figure 8 - Illustration of the construction of a typical water supply pipeline 15

Figure 9 - Construction of a recent water supply pipeline by Wessex Water 16

Figure 10 - The River Wylye SAC from Boyton Bridge 19

Figure 11 - The Landscape around Fontmell and Melbury Downs SAC 20



Introduction A planning application has been submitted by Atkins Ltd on behalf of Wessex Water Services Ltd for the

Corfe Mullen to Salisbury Transfer Scheme (the Scheme).

The Scheme consists of a large section of new buried water supply pipe, together with associated pumping

stations and water storage tanks located on a series of ten new or extended sites. It forms an essential part

of Wessex Water’s Integrated Water Supply Grid network that will distribute water from areas of surplus to

areas of need.

The planning application has been submitted to three planning authorities: Wiltshire Council, East Dorset

District Council and North Dorset District Council, as the Scheme crosses all three administrative areas. The

approximate route of the pipeline and the new development sites are illustrated in Figure 1 below.

This Non Technical Summary forms Volume 1 of the Environmental Statement, which has been prepared to

accompany the planning application and provides an overview of the need for the scheme and alternatives

considered, the environmental impacts of the Scheme and the measures proposed to mitigate those

impacts.

Why is the Scheme Needed? The Integrated Grid programme is a series of linked projects to allow Wessex Water to resolve a number of

issues with their water supply network. In simple terms, the Integrated Grid involves improving connections

within the existing water supply system to enable water to be moved from areas where it’s available to areas

where it’s needed.

In summary, the Integrated Grid is required to enable Wessex Water to meet the following legal and

regulatory obligations:

The legal obligations in National Environment Programme issued by the Environment Agency,

specifically associated with reductions in the amount of water that Wessex Water can extract from

certain underground water sources from 2018 onwards, as required under the EU Habitats Directive;

The legally binding undertaking agreed with the Drinking Water Inspectorate, to ensure compliance

with Water Supply (Water Quality) Regulations 2000, associated with high levels of nitrates in certain

untreated water sources largely from agricultural fertiliser;

The regulatory outputs set by Ofwat, associated with the security of water supply to their customers

served by a single source of water only; and

The statutory duty to balance the supply of and demand for water up to the year 2035 as set out in the

Water Resources Management Plan approved by Defra in 2010.

The Corfe Mullen to Salisbury Transfer Scheme is a key component within the Integrated Grid. It will provide

a new pipeline system that will link together the southern and central areas of the Company’s supply network

and enable the improved transfer of water between these different areas to help meet these obligations. An

illustration of the location of each of the sites where these issues will be resolved by the Scheme is shown in

Figure 2.

The Scheme will provide benefits from:

Reduced abstractions from four existing underground water sources leading to flow improvement in the

Rivers Wylye and Bourne;

Maintenance of drinking water quality for 140,000 water consumers; and

Provision of a more secure water supply for 88,000 water consumers.



Figure 1 – Schematic of The Corfe Mullen to Salisbury Transfer Scheme



Figure 2 - Illustration of the key issues that will be resolved by the Scheme

The Proposed Scheme

Alternatives Considered Wessex Water’s supply strategy for the future needs to satisfy a number of key objectives:

Meeting the demand for water over the next 25 years and enabling the reductions in groundwater

abstraction required by the Environment Agency to improve flows in some rivers and protect their

ecology.

Maintaining drinking water quality, when the quality of untreated water at certain underground water

sources is worsening, particularly due to increasing concentrations of nitrates largely from agricultural

fertiliser – as required by the Drinking Water Inspectorate.

Meeting customer expectations for a reliable water supply, established through customer research.

Specifically this involves improving the security of water supply to customers, even in the event of a

catastrophic failure of a water source or treatment works – as agreed with Ofwat.

In order to ensure that it meets Statutory, Regulatory and legal obligations, failing to resolve these objectives

(i.e. doing nothing) is not a viable option for Wessex Water.

Every five years water companies in the UK prepare a strategic Water Resources Management Plan

(WRMP). This plan outlines how Wessex Water intends to ensure a reliable water supply to their customers

over the next 25 years. The need and alternatives for the Integrated Grid, and hence for the Scheme, was

first considered within the WRMP.

Blandford

Shaftesbury

Existing network

Corfe Mullen to Salisbury Transfer Scheme

Sources with nitrate issues, directly resolved

by Corfe Mullen to Salisbury Transfer Scheme

Stand alone sources connected into wider supply

Network by Corfe Mullen to Salisbury Transfer Scheme

Groundwater abstraction licence reduction in 2018

Area of future predicted water supply-demand deficit

LEGEND

B R

E L

Bristol

Bath

Chippenham

Salisbury

Bournemouth

Poole

Dorchester

Taunton

Bridgwater

Yeovil

http://www.wessexwater.co.uk/WorkArea/linkit.aspx?LinkIdentifier=id&ItemID=136



Wessex Water considered over 100 options to meet the company’s key objectives and identified the best

solution in terms of ability to supply the water required, environmental impacts (including the carbon footprint

of each), cost and compliance with environmental law. This process is illustrated in Figure 3 below.

Figure 3 - Options Identification and Assessment Process

Using the best options for each area an integrated approach was compared with the traditional alternative of

providing individual solutions for each of the drivers.

The assessment showed that the benefits of the integrated approach were significantly greater than the

costs. Furthermore the environmental and social impacts of the integrated approach were less than the

alternative. Therefore, the Grid concept satisfied all of Wessex Water’s key objectives and had fewer

environmental and social impacts and hence was adopted.

Once the overall concept for the Grid had been established and consulted upon through Wessex Water’s

published WRMP and business plan, a series of more detailed alternative options were then investigated in

more detail to ensure that the chosen layout for the Scheme was the best. A staged approach was applied

in order to logically identify the best solution from a number of competing alternatives.

Stage 1 – ’The long list’: Consideration and assessment of eight regional Grid routes to move water

between the Poole and Salisbury areas. Two preferred routes were short-listed and are illustrated in

Figure 4 along with the eight original options.

Stage 2 – ’The short list’: Consideration of the details of the two short-listed alternatives from Stage 1,

using a range of criteria including environmental impacts, water quality, future and operational flexibility

and ease of construction. This resulted in the selection of a single preferred way to transfer water

between Corfe Mullen and Salisbury via Shaftesbury and Blandford.

The preferred option was found to have fewer environmental impacts, was considered cheaper and

safer to build and avoided the need for new water treatment works as it made better use of existing

groundwater sources.

Plan B

Individual solutions

• traditional approach

• each driver considered

separately

Plan A

Integrated approach

• align strategies

• maximise synergies

Options identification and

assessment

• to meet demand to 2035

• to accommodate low flows

reductions

Feasible options


assessment

• to deal with deteriorating

raw water quality


assessment

• to improve security of

supply to stand alone

sources

Feasible options Feasible options

Water resources Drinking water quality Security of supply

Option identification and assessment process

Water resources Drinking water quality Security of supply

Option identification and assessment process



Stage 3 – ’The best regional route’: Consideration and selection of different route options for the

pipeline and of different sites for the associated pumping stations and storage tanks in order to provide

the best engineering solution whilst avoiding, where possible, areas of environmental sensitivity.

Stage 4 – ’The best overall route’: Consideration and assessment of options to accommodate known

local ‘pinch-points’ in the preferred regional route identified from Stage 3.

Figure 4 - Illustration of the ‘long list’ alternatives and the two chosen ‘short-list’ alternatives

2

Existing network

Grid concept alternative options

LEGEND

B R

E L

Bristol

Bath

Chippenham

Salisbury

Bournemouth

Poole

Dorchester

Taunton

Bridgwater

Yeovil

16

34

5

7

8

2

Whitesheet storage tank

Existing network

Short-listed alternative concept 1

Short-listed alternative concept 2 – preferred option

Common new pipeline for both concepts

LEGEND

B R

E L

Bristol

Bath

Chippenham

Salisbury

Bournemouth

Poole

Dorchester

Taunton

Bridgwater

Yeovil

Salisbury

Shaftesbury



This extensive options appraisal process has resulted in the final Scheme that is presented and assessed

within the Environmental Statement. The environmental impacts that cannot be avoided due to engineering,

operational and flow requirements have been assessed through the Environmental Impact Assessment with

the intention to reduce the environmental effects from development as much as possible.

A map of the final Scheme that has been selected is shown in Figure 5 below, illustrating the pipeline route

and the location of each of the pumping stations and storage tanks. The local planning authority boundaries

are also shown to help illustrate the relative amount of the Scheme within each area.



Figure 5 - Map of the Scheme showing route and Local Planning Authority boundaries

SECTION 6



Description of Development

Sturminster Marshall to Summerslade Down The Scheme will use an existing pipeline to transfer water between Corfe Mullen Water Treatment Works

(WTW) and Sturminster Marshall WTW.

The water supply pipeline between Sturminster Marshall and Summerslade Down is approximately 44km

long, with connections to the existing Wessex Water storage tanks at Snowsdown and Littledown along the

route.

In addition to the new pipeline, a number of new pumping stations and storage tanks are required along the

route to ensure the effective operation of the water supply system. Indicative illustrations of what the storage

tanks and large pumping stations will look like once constructed are provided in Figure 6 and Figure 7. The

storage tanks will be partially buried and grass covered. Landscape planting is provided around the pumping

station, especially around the ancilliary equipment outside the building, to screen it from the site entrance.

Consequently, and to allow vehicle access to all areas, the access road is extended around the whole

pumping station building.

The storage tanks are required along the pipeline route to provide a store of water near to customers, which

can be used to balance variable customer demands throughout the day. The storage tanks along the

Scheme also help to maintain a safe and efficient water pressure in the pipeline.

Figure 6 - Illustration of an example of a large pumping station, once constructed



Figure 7 - Illustration of a typical storage tank, once constructed

The locations of these sites are primarily determined by the need to locate them adjacent to existing Wessex

Water sites along the route of the proposed pipelines, but also take account of engineering requirements,

topography and environmental sensitivity. The main sites along the southern section of the route are:

Corfe Mullen pumping station. A new pumping station, located within the existing operational site

boundary at Corfe Mullen Water Treatment Works (WTW). The temporary construction area on the

existing site will be between 1.5 and 2 hectares (roughly the size of 2 ½ football pitches) and the new

building will be approximately 17m long, 9m wide and 6.5m high.

Sturminster Marshall storage tank and pumping station. Two new storage tanks connected to a

new pumping station are required on land located directly to the west of the existing water treatment

works at Sturminster Marshall. The temporary construction area will be approximately 5 hectares

(roughly the size of 7 football pitches). The temporary construction area is relatively large at

Sturminster Marshall as it will also be used as a construction and material storage hub for the pipeline.

The new storage tanks will hold 5 million litres of water (equivalent to 2 Olympic swimming pools) and,

overall, the building for the new tanks and pumping station will be approximately 45m long and 65m

wide with a roof that is 9m high.

Snowsdown storage tank. A new storage tank is required at Snowsdown adjacent to the existing

Wessex Water storage tank. The temporary construction area will be just under 2 hectares (roughly the

size of 3 football pitches). The new storage tank will have a capacity of 3 million litres (equivalent to just

over 1 Olympic swimming pool) and will be approximately 55m long, 25m wide and 4 – 5m high.

Pimperne pumping station. A new pumping station is required to the west of Pimperne to allow water

to be pumped from Snowsdown storage tank to Littledown storage tank. The new pumping station will

be located adjacent to existing agricultural buildings, west of the village of Pimperne. The temporary

construction area for the new site will be a little less than 2 hectares (slightly greater than the size of 2 ½

football pitches) and the new building will be approximately 18m long, 18m wide and 7.5m high.

Littledown storage tank. A new storage tank is required at Littledown adjacent to the existing Wessex

Water storage tank. The temporary construction area will be between 1.5 and 2 hectares (roughly the



size of 2 ½ football pitches). The new storage tank will have a capacity of 2 million litres (equivalent to

about ¾ of an Olympic swimming pool) and will be approximately 20m long, 25m wide and 5m high.

Monkton Deverill pumping station. A new pumping station is required at Monkton Deverill to allow

water to be pumped between Littledown and the new storage tank at Summerslade Down. The new

pumping station will be located adjacent to existing agricultural buildings, south of the village. A new

cross connection to the existing water pipeline between Whitesheet storage tank and Codford WTW is

also required at Monkton Deverill. The temporary construction area will be just over 1 hectare (roughly

the size of 1 ½ football pitches) and the new building will be approximately 36m long, 15m wide and 8m

high.

Summerslade Down storage tank. A new storage tank is also required at Summerslade Down. The

temporary construction area will be approximately 4.5 hectares (roughly the size of 6 football pitches).

The temporary construction area is also relatively large at Summerslade, as at Sturminster Marshall, as

it will also be used as a construction and material storage hub for the pipeline. The new storage tank

will have a capacity of 8 million litres (equivalent to just over 3 Olympic swimming pools) and will be

approximately 43m long, 58m wide and 5m high.

Codford to Camp Hill The Scheme will use an existing pipeline between Summerslade Down and Codford WTW. This section will

comprise 19km of new water pipeline between the existing Codford WTW and the existing Wessex Water

storage tank at Camp Hill. The pipeline route runs along the Wylye valley running to the south of the River

Wylye and the Warminster to Salisbury railway line for the majority of its length. The following works are

also required as part of the Scheme:

Codford WTW. A new pumping station and storage tank is required at the existing Codford WTW. In

addition, improvements are also required to upgrade and extend the existing water treatment works.

The new pumping station, storage tank and water treatment facilities will be located on land directly to

the west of the existing Wessex Water site. Overall the temporary construction area for this site will be

approximately 2.5 hectares (roughly the size of 3 ½ football pitches). The pumping station building will

be approximately 30m long, 15m wide and 8m high. The new storage tank will have a capacity of 2

million litres (equivalent to about ¾ of an Olympic swimming pool) and will be approximately 25m long,

20m wide and 7m high.

Wylye WTW. An additional pump building will be constructed on an extended operational site at Wylye

WTW. The temporary construction area on the existing site at Wylye will be relatively small (40m x

20m) and the new building will be approximately 4m long, 3m wide and 2m high.

Camp Hill storage tank. A new storage tank is required at the existing Wessex Water site at Camp

Hill. The temporary construction area will be approximately 3 hectares (roughly the size of 4 ½ football

pitches). As for Sturminster Marshall and Summerslade, the temporary construction area is relatively

large here as it will also be used as a construction and material storage hub for the pipeline. The new

storage tank will have a capacity of 5.6 million litres (equivalent to just under 2 ½ Olympic swimming

pools) and will be approximately 42m long, 32m wide and 5m high.

Description of Construction Construction of the Corfe Mullen to Salisbury Transfer Scheme will commence in summer 2013 for

completion by 2018.

To build the pipeline, the width of the area affected will typically be 20 - 25m along the length of the Scheme,

but this may increase locally to around 30 - 35m where the pipeline crosses roads, watercourses, railways

and the like to facilitate safe working. At hedge crossings this will typically be reduced to 5m in order to

minimise the length of hedge affected.



Typically minor roads, byways, footpaths and other rights of way will be crossed using open cut construction

meaning that the pipeline will be laid in an open, excavated trench as shown on Figure 8. This means that

these rights of way will be subject to temporary closure whilst the pipeline is constructed across them.

Where hedges are crossed using open-cut techniques, a short length (5 – 10m) of hedgerow is typically

removed prior to the pipeline trench being excavated. Once the pipeline has been laid in the trench, it is

backfilled with soil and the hedge is reinstated with new planting to minimise impacts.

Smaller watercourses and ditches will also be crossed using open cut techniques where practicable and in

agreement with the regulatory authorities. Water flow will be maintained down the watercourse during

construction. After laying the pipe, trenches will be filled in with soil and normal water flow will be restored.

The banks and bed of the watercourses will be returned to their original form.

Where more major or very sensitive obstacles are encountered, such as primary roads, railways, major

watercourses or ecologically valuable hedgerows it is possible to install pipes without digging a trench,

typically using directional drilling or auger boring, where a tunnel or passage is cut under the crossing and

the pipe inserted into this.

A typical illustration of a water supply pipeline being constructed is provided in Figure 8 below and an

example from a recent pipeline project undertaken by Wessex Water is shown in Figure 9.

Figure 8 - Illustration of the construction of a typical water supply pipeline



Figure 9 - Construction of a recent water supply pipeline by Wessex Water

Environmental Impact Assessment

Methodology Environmental Impact Assessment (EIA) is a procedure that ensures that the environmental implications of

decisions are taken into account before the decisions are made.

The planning application site for the Scheme has been drawn widely to incorporate the required construction

works and also the potential for minor route re-alignment (within a typically 50m wide corridor) to avoid

unforeseen environmental features as the Scheme progresses. It is also partially in outline with only the

maximum height, width and length of the new pumping station buildings defined – the details of their design

and appearance will be subject to further, more detailed planning approval. The design of all parts of the

Scheme has been developed to a stage, however, which can reliably inform the EIA process. In addition the

scope of the EIA has been agreed with the planning authorities.

The Scheme has been assessed in terms of the following environmental effects:

Direct, indirect and secondary effects;

Short, medium and long term effects;

Permanent and temporary effects;

Positive and negative effects; and



Cumulative effects with other projects, plans and policies;

The significance of potential impacts has been considered by taking account of the importance of the

environment that is impacted by the Scheme and the magnitude of any impacts. A summary of the main

findings of this assessment is provided below.

Planning Context Overall, the Scheme is consistent with national, regional and local planning policy and the conclusion of the

assessment is that the scheme provides a neutral, but marginally beneficial impact in respect of key

planning objectives.

The key findings of the assessment are:

Sustainable infrastructure to support the economy and society - Future growth is underpinned by

the provision of sustainable infrastructure such as water supply. The requirement for a resilient water

supply is in the public interest and essential to the local and regional economy. Accordingly, the

development is compliant with and beneficial to both national and regional growth policies.

Climate Change - The Scheme is considered compliant with and beneficial to national and local climate

change policies and objectives. Wessex Water provides 19% of its energy usage from renewable

sources and is taking active steps to increase this provision further.

Development on the Green Belt - The Scheme is considered to be consistent with the policies of

Green Belt protection. The water supply requirements of the Scheme cannot be satisfied by

development on land outside the Green Belt.

Development on the Area of Outstanding Natural Beauty (AONB) - Due to the regional nature of the

Scheme and the areas it connects, there is no scope for avoidance of the AONB. It is considered that

the exceptional circumstances demanded for development in the AONB are met and accordingly the

Scheme is considered to be consistent with policies on development in the AONB.

Protection of historic assets – Whilst the route of the new pipelines passes through various areas of

archaeological sensitivity, it has been located to avoid designated assets of historic importance. The

Scheme is considered to be consistent with the policies of heritage protection.

Protection of nature conservation assets - The measures employed during the design of the Scheme

and through mitigation during construction will ensure that any adverse impacts from the Scheme on

nature conservation assets can be avoided, mitigated or compensated for. Accordingly the Scheme is

considered to be consistent with national and local nature conservation policies.

Agricultural land – The Scheme is considered to be consistent with agricultural land policy, as only a

very small area of higher grade agricultural land is permanently lost, no agricultural businesses or

agricultural practices are compromised by the Scheme, and any temporary loss of crop during

construction will be compensated for.

Protection of residential and other amenities - With measures in place to mitigate the temporary and

permanent impacts, any local adverse impacts on public amenity as a result of the Scheme are

outweighed by the more widespread benefits from the provision of a reliable water supply for

communities. All public rights of way affected by the Scheme will be diverted temporarily. Therefore,

the Scheme is considered consistent with residential and amenity protection policies.



Ecology and Nature Conservation

Existing Environment The Scheme is located in open countryside. In the south, the Sturminster Marshall to Summerslade Down

section of the pipeline follows the relatively low lying River Stour Valley. The route steadily rises on

increasingly open chalk down to the top of Fontmell Hill south of Melbury Abbas, and then drops to flatter

ground to the east of Shaftesbury and drops again to an area of low lying heavy soils to the east of

Motcombe and Mere. To the north of the A303, the route rises again to higher chalk downs.

The Codford to Camp Hill section is largely situated in the River Wylye valley although it rises to higher chalk

downs at its eastern end.

Construction Impacts The largest potential for ecological impacts is during and immediately following the construction of the

pipeline, and relates to potential direct damage to habitats and potential disturbance or harm to species living

within them. The majority of habitat impacted by the Scheme comprises arable and agriculturally improved

pasture fields, both of which are of modest or limited ecological value. The most notable exceptions are

limited impacts on two sites designated for their nature conservation value and habitats including ditches

small rivers and hedges.

International Designations

The proposed pipeline section between Codford to Camp Hill crosses the River Wylye in two locations. This

river is part of the River Avon Special Area of Conservation (SAC) which is internationally designated for its

chalk stream habitats and species. The River Wylye from Boyton Bridge is illustrated in Figure 10. Potential

for impacts will be largely avoided here by use of directional drilling or auger boring (as discussed previously)

to install the pipe beneath the river bed. Residual pollution risks will be managed by careful management of

the construction works as defined by the Construction Environmental Management Plan.

The proposed pipeline route runs close to the Fontmell and Melbury Downs SAC. This area is internationally

designated for its population of a rare chalk flower (the Early Gentian) and also for chalk downland habitats.

The route of the pipeline in this area has been carefully designed to minimise, where possible, impacts upon

the important designated habitats and features. The high quality of the grassland environment in this area is

illustrated in Figure 11.

However, the pipeline in this area does impact grassland habitat adjacent to the designation, including two

areas designated at the county level which is considered to have some ‘buffering’ effect on the internationally

designated habitats. Works in these areas will be undertaken and managed using specialist techniques to

minimise the chances of accidental damage and to allow rapid recovery of that habitat which is directly

impacted by the construction works.

Overall, the Scheme is assessed to have a short term but moderate adverse effect on these two habitats

prior to mitigation works.

National Designations

There will be a direct and unavoidable impact on Ebsbury Down Site of Special Scientific Interest which is

nationally designated for its chalk grassland habitats. The impacted area represents around 0.1% of the

designation and comprises very degraded habitat of neutral ecological value.



County Designations

The entire route will have direct impacts on a five county designated sites. In all instances careful

construction management and restoration are proposed and impacts are considered be minor. As a result of

these impacts Wessex Water will facilitate nature conservation orientated habitat management works on

these sites or similar sites in the wider countryside.

Figure 10 - The River Wylye SAC from Boyton Bridge



Other Habitats and Species

All of the proposed surface sites fall within areas of less valuable (non-designated) habitat, largely

comprising arable or improved pasture or existing Wessex Water operational land. There will be a

requirement to remove a small amount of hedge at the Sturminster Marshall and Littledown sites and some

trees at the Camp Hill storage tank site. This will be compensated by on site planting.

During construction, the effects on non designated habitats and species include potential impacts on hedges,

ditches and rivers. As for the Wylye, on other major watercourse crossings, the impacts will be avoided

through directional drilling or auger boring below the river bed. However, other features will predominantly

be crossed by using open trenches into which the pipeline will be laid. This will lead to a requirement for the

removal of hedges and hedge vegetation, which will be kept to a minimum, and where possible removal of

trees will be avoided. Hedgerow habitats will restored and replanted where appropriate and in agreement

with landowners.

Particular consideration has been given to impacts on protected species including nesting birds, great

crested newts and dormice as these species have the highest potential to be affected. The overall impacts

on these species are considered to be temporary during construction and their subsequent recovery should

give rise to no permanent impact on populations. To further mitigate impacts Wessex Water proposes to

assist in the continued funding of the existing South Wiltshire Farmland Bird project officer covering the area

and to encourage the undertaking of enhancement works in habitats across the wider countryside.

Overall, the Scheme is assessed to have a short term, minor adverse effect on the national and local

designated areas and on local protected species prior to mitigation works.

Figure 11 – View east from Fontmell and Melbury Downs SAC



Operational Impacts For the most part, the Scheme will have no operational impacts on ecological features. The one exception

will be the need to discharge treated water into watercourses including the River Wylye, from storage tanks

typically at 5 year intervals and approximately once every 10-20 years for washouts along the pipeline for

routine cleaning and maintenance. Any such water would be subjected to de-chlorination before discharge,

and wherever possible particularly sensitive times of the year would be avoided. Consequently, these

operational impacts are considered to be minor.

Overall Where moderate or minor adverse impacts are identified, these effects will be mitigated through careful

habitat re-instatement and enhancement will be sought wherever possible in both designated and

undesignated areas. Ecological monitoring during construction and species disturbance licenses will further

mitigate impacts. As a result of these habitat reinstatement and enhancement mitigation measures, in

combination with the temporary nature of the majority of the impacts identified and the lack of significant

operational impacts, the scheme is assessed to have a negligible to slight adverse impact on ecology and

nature conservation.

Historic Environment

Existing Environment The Historic Environment encompasses cultural heritage from as early as the Palaeolithic period through to

the modern era. These heritage assets include designated and non-designated archaeological remains,

historic buildings and structures and historic landscapes.

In view of the known archaeological potential of the area traversed by the Scheme, a desk study was

augmented by preliminary field investigations in the form of geophysical surveys (radar based surveys to

highlight interesting buried features) covering all infrastructure sites and targeted sections of the pipeline

route where archaeological potential was considered high. Based on these results further targeted trial

trenching was then undertaken to help determine the nature, extent, date and condition of buried remains to

inform the Environmental Statement and any recommendations to mitigate and reduce impacts.

It has been determined that the pipeline has the potential to affect archaeology remains dating anywhere

between the Prehistoric and Modern periods. However, the geophysical surveys and evaluation undertaken

suggests an overall low density of archaeological features, which in part is due to the sensitive design of the

Scheme in which significant known settlement, built heritage and historic landscape features have been

avoided (during Stage 3 of the consideration of alternative routes for the Scheme outlined earlier).

Construction Impacts The Scheme will have a direct physical impact on a limited number of significant known landscape and

archaeological features and a number of significant previously unknown buried archaeological remains

discovered during the preliminary investigations. Following appropriate mitigation the overall effect on these

assets will be as follows:

Moderate Adverse impacts on:

Sturminster Marshall WTW extension - suspected Prehistoric burnt mounds, Bronze Age settlement

activity;



Codford WTW extension - Bronze Age settlement evidence and possible 17th century water meadow

systems;

Camp Hill storage tank site - suspected Prehistoric enclosure and field system associated Iron Age

settlement; and

Pipeline section between Sturminster Marshall and Littledown storage tank, adjacent to Bishops Court

Farm - Prehistoric settlement, possibly associated with round barrow.

Slight Adverse impacts on:

Pimperne Infrastructure site - Iron Age settlement activity associated with enclosure;

Various features along the pipeline route including strip lynchet associated with scheduled cross dyke,

Bronze Age/Iron Age linear dyke, Bronze Age/Iron Age linear dyke associated with scheduled cross

dyke, Roman activity and possible metal working site, Roman road; and Bronze Age/Iron Age ditch

associated with scheduled cross dykes.

Preliminary investigations have also identified significant archaeological remains within a further ten localised

sections mainly along the Codford to Camp Hill pipeline route. Field evaluations are currently being

undertaken at these sites, and mitigation recommendations will be confirmed following completion of this

work. The Scheme will also affect the setting of the scheduled medieval strip lynchets at Monkton Deverill,

although careful design of the site and screen planting in keeping with the modern landscape will reduce the

effect to a slight adverse impact only.

Grade II listed Dover House near Codford WTW will have very limited views affected looking out across the

river at Boyton towards the proposed infrastructure site at Codford. Screen planting in keeping with the

landscape character of the area will neutralise the impact.

Operational Impacts The impacts on heritage assets from operational activity will be negligible. Operational traffic movements

(which may affect the amenity experience of historic features) will be minimal and maintenance works are

likely to take place in already disturbed ground such that there is little potential for further disturbance of

archaeological features.

Overall In conclusion, there will be a limited number of significant archaeological sites that will be physically

impacted by the Scheme. The route chosen avoids most of the known heritage features along the route and

the narrow width of the pipeline trench and small number of intermediate sites minimises the scale of any

potential impacts. Additionally, an archaeologist will be present during the construction of the highest risk

areas to minimise the risk of impacts occurring. Where impacts are unavoidable, these will be mitigated

through targeted archaeological excavation and recording, reducing the overall adverse effect of the

Scheme. Twelve sites are still undergoing preliminary investigations; however, considering the Scheme will

have a moderate adverse effect on just four sites at this time and given the great length of the Scheme, the

Scheme overall is assessed to have a slight adverse effect on the historic environment.

Landscape

Existing Landscape Character The proposed Scheme crosses Wiltshire, North Dorset and East Dorset, each of which has an extremely rich

geological, ecological and cultural landscape. This diversity contributes to a distinct landscape character



resulting in nationally designated areas including the Cranborne Chase and West Wiltshire Downs Area of

Outstanding Natural Beauty (AONB), the principal protected landscape affected by the Scheme and covering

approximately two thirds of the overall Scheme area.

Corfe Mullen to Summerslade Down Section

The Scheme passes through rural landscapes within East Dorset, North Dorset and Wiltshire. The pipeline

passes close to rural villages, hamlets and scattered farmsteads which have various historical features,

some of which are classified as Conservation Areas.

The scheme environment comprises open countryside with undulating and steep scarps. The fields are

large-scale offering extensive views across the surrounding landscape. Land cover includes arable and

pasture fields with dense hedgerow boundaries to fields. The area has a rich history with many Scheduled

Ancient Monuments located along the route including historic churches within settlements. Figure 11

illustrates the landscape of the area around Fontmell and Melbury Downs SAC, to the south of Shaftesbury.

Codford to Camp Hill Section

The Scheme passes through rural landscapes within west and south Wiltshire. The Salisbury to Winchester

railway line defines much of the built landscape along this section as it runs along the valley floor to the north

of the pipeline. The Scheme passes close to rural villages, hamlets and scattered farmsteads.

The development has a rural setting with open, undulating and steep scarps rising from the river valley.

Where the land rises, fields become more large-scale offering extensive views across the surrounding

landscape. Where the land falls the landscape is more enclosed and increasingly vegetated with woodland

copses and scattered tree belts.

Construction Impacts The new pipeline gives rise to temporary impacts. Whilst there will be ground disturbance and vegetation

loss along the pipeline route within the construction area, the route is located within predominantly open

agricultural landscapes which will quickly return to arable use or pasture. The route has been carefully

selected to avoid woodland areas and lengths of important, mature hedgerow.

The proposed pumping station and storage tank sites are generally well contained from the surrounding rural

landscape due to dense vegetation screening or by nature of the surrounding landscape. The proposed

building style at the pumping stations are generally in keeping with the wider landscape character and

features associated with the local area in terms of scale, land use, visual balance, colour, interest and

texture. In general, existing vegetation and/or new boundary planting screens the interior of the sites. There

are generally few nearby properties or amenities, therefore the sites generate limited impacts upon the wider

landscape character. The planning of the Scheme has sought to achieve two landscape and visual

objectives, first to minimise the visual impacts of the proposals and second to enhance the natural

environment.

The majority of temporary and permanent impacts will occur during the construction phase. In respect of the

pipeline route, the main changes that have the potential to affect the landscape are where the pipeline route

causes loss of boundary hedgerows, mature trees, arable land and areas of pasture/grassland. On the

surface sites, an increase in size and visual prominence of the structures will have a potential effect on the

landscape.

The Scheme proposals include mitigation measures such as replanting and in sensitive areas, techniques

such as translocation of hedgerows and trees. It is likely that the replanted hedge and trees will be notably

younger and less effective as a visual screen until they have fully established and matured which may take

several years.



Operational Impacts Generally the additional surface sites will increase the visual intrusion into the wider landscape. The severity

of the impact will be offset by the distance from nearby properties and people and mitigation measures such

as planting to help screen the sites.

The proposed developments are considered to be of the scale and type which can be accommodated with

limited harm to the local and wider landscape setting. Subject to the implementation of measures to

enhance local biodiversity and visual amenity, the landscape and visual impact of development can be

minimised to an extent which is compliant with the aims of landscape policy, protection of the countryside

and, in particular, conformity with AONB aims and objectives.

Overall With the implementation of sensitive building design and appropriate landscape planting and mitigation,

overall, the proposed development of the Corfe Mullen to Salisbury Transfer Scheme is anticipated to have

slight adverse impact on the landscape resources and visual amenity of the local area.

Water Environment

Existing Environment The water environment in the study area is very diverse and includes features, such as the River Avon, River

Wylye, River Lodden and the River Stour, that are of very high quality. These rivers and the habitats around

them are home to important species and their quality and extent need to be protected.

The proposed works will have a number of long lasting positive impacts on the water environment including

indirect benefits for both river flows and groundwater levels. This is particularly true as the Scheme enables

Wessex Water groundwater abstraction to be reduced in the upper River Avon catchment, without the need

for additional new sources of water, to the direct benefit of the flows and ecology of the Avon river

catchment.

Construction Impacts The potential negative water related impacts that have been identified primarily result from the construction

phase; particularly where works are in proximity to a river or over vulnerable groundwater aquifers

(vulnerable because the soil over it easily lets pollutants soak through). The main anticipated adverse

impacts relate to:

The risks associated with construction works over groundwater aquifers that are used for public water

supply;

The risks associated with sediment or pollution runoff from construction compounds;

The risks associated with completing the pipeline river crossings during the construction phase; and

The construction of new structures and buildings where they could be at risk of flooding.

These potential negative impacts upon water quality will be minimised through careful construction practices

as defined in the Construction Environmental Management Plan.



Operational Impacts Operational impacts are limited to water quality impacts to the local watercourses from washouts operated

typically at 5 year intervals for storage tanks and approximately once every 10-20 years for washouts along

the pipeline for routine cleaning and maintenance. Any such water would be subjected to de-chlorination

before discharge, and wherever possible particularly sensitive times of the year would be avoided. The flow

and water quality of the discharges are designed to meet the Water Quality Standards and minimise

potential impacts upon the environment. Consequently, these operational impacts are considered to be

minor.

Overall With the implementation of suitable construction techniques in accordance with the Environment Agency’s

Pollution Prevention Guidelines and techniques such as directional drilling beneath major watercourses, the

potential minor / moderate adverse construction impacts can be significantly reduced. Operationally, the

scheme has a major beneficial impact as it will allow the long term permanent improvements in quality and

flow of the River Avon watercourses through reduced abstraction, which will also help to improve

groundwater levels in the catchment. Overall, the Scheme is assessed to have a major beneficial impact

on the water environment.

Traffic and Transport

Traffic Environment For the construction phase, the potential impacts of the Scheme on traffic and transport result from road

closures and diversions, increases in construction traffic and access arrangements to temporary pipe store

compounds and new pumping station or storage tank sites. For the operational phase sources of impacts

include trip generation and permanent access for operational vehicles to the permanent surface sites.

Construction Impacts For the construction phase transport impacts can be summarised as follows:

The predicted movement of vehicles (construction traffic) to the surface sites is assessed to be of

neutral / minor adverse significance. The impact will be minimised by ensuring that construction

vehicles deliver / remove from the sites outside of peak hours and that construction traffic journeys are

minimised where possible.

There will need to be a temporary closure and traffic diversion at Spread Eagle Hill over a three week

period, and the impact on access to National Trust land in the area is an acknowledged disturbance for

local users. This road closure cannot be avoided due to the sensitivity of the surrounding environment

and factors associated with the safety of the construction works.

All direct impact on major traffic routes is avoided through directional drilling of the pipeline crossing

under the main roads.

Routes for construction vehicles have been provided and mitigation measures have been identified

where necessary.

Some of the highway accesses to pipe store compounds and new surface sites will require mitigation

measures in order to improve the access visibility, such as hedgerow lowering. One of the new surface

water sites, at Camp Hill storage tank will require a new access from the highway to ensure safety.



The significance of the impact on footways and cycle routes is negligible.

The potential adverse impact on bus routes will be avoided through mitigation measures in terms of the

timing of open cut construction and resultant road closures.

These impacts are collectively considered to have a negligible / minor adverse effect on traffic and transport.

Operational Impacts For the operation phase impacts can be summarised as follows:

The trip generation impacts associated with the operational phase of the Scheme are considered to be

negligible as the sites are unmanned.

Access arrangements will be improved at a number of existing sites.

The operational impacts are considered negligible.

Overall With the implementation of suitable mitigation works, including the timing of works to avoid or minimise

adverse effects on road users, temporary diversions to public rights of way and creation of site accesses

during construction, the Scheme is considered to have a negligible to slight adverse effect on traffic and

transport.

Noise and Vibration

Noise Environment The Scheme environment is predominately rural where the principal noise sources are bird song, normal

farming activities, occasional aircraft, and road traffic noise. The road traffic noise typically originates from

local roads with little traffic and in some cases from distant, faster roads. The noise levels at some areas in

the northern section are also influenced by railway noise. In the more populated areas, additional noise

sources include general residential activities.

Construction Impacts The main construction impacts due to noise and vibration are as follows:

At most residential locations, the noise impact associated with installation of the pipeline is insignificant.

The assessment indicated that there would be a slight adverse noise impact at a very small number of

residential properties which are within 100m of the construction works. The impact would be expected

to last for approximately 4 days and will be mitigated through temporary noise reduction barriers during

construction.

Vibration resulting from the use of a directional drill at a major crossing point may be perceptible at

dwellings within 20 - 30m. However it is unlikely to cause damage to buildings within this distance

range. There are only 4 properties at or within 30m of the pipeline works.

During the construction of the pumping stations and storage tanks, a slight adverse noise impact is

predicted for the nearest properties to Wylye, Sturminster Marshall and Snowsdown. The nearest

residential property to Corfe Mullen WTW would be subject to a moderate adverse impact during

construction.



To minimise construction impacts, it will be necessary to employ construction best practice. In addition,

noise bunds/barriers and enclosures may need to be considered. Local residents will be kept informed

of the progress of the works.

The assessment of the temporary traffic diversion in the vicinity of Spread Eagle Hill indicated that a

minor to moderate adverse impact may occur for the three week diversion period.

No significant noise impacts are expected from construction vehicle movements to the surface sites or

temporary construction compounds.

Overall, without mitigation, the potential construction impacts are considered to be slight adverse.

Operational Impacts There are no substantive noise sources at the proposed storage tanks, and significant noise impacts are not

expected.

The daytime noise assessment at the pumping station sites indicated that at all but one location (one

property close to the Corfe Mullen site) the noise from the pumping stations is expected to be below the

existing noise levels.

The night time assessment indicated that the noise impact will be insignificant at the closest residential

properties.

A design requirement will be placed upon all of the pumping stations buildings, in order to limit the external

ambient noise level to avoid any noise impacts at nearby residential properties.

The assessment of additional vehicle movements indicated that there will be a negligible impact on noise

levels when the Scheme is operational.

Overall With the implementation of suitable construction mitigation measures, such as consultation with those

potentially affected, daytime working along the pipeline and noise reduction fencing on the sites, along with

adherence to design requirements to reduce operational noise emissions from buildings, overall the Scheme

will have a negligible effect on the noise environment.

Air Quality

Existing Environment The air quality within one kilometre of the pipeline route is considered to be relatively good. Air quality could

be affected during construction of both the pipelines and the surface sites by excavation and by the

movement of construction vehicles.

Construction Impacts The assessment showed that dust emissions could increase during excavation of the pipeline trench or at

surface sites and through vehicle movements along the pipeline route. However, the potential significance of

such dust emissions would be neutral if best practice mitigation measures are applied and Pollution

Prevention Guidelines adhered to.

Changes in air quality as a result of additional construction vehicles travelling to and from construction sites

would be negligible as would those resulting from any road diversions. Both would be temporary and cease

on the completion of the construction works.



Operational Impacts There would be no significant effect on air quality during the operation of the Scheme.

Overall Overall, with the implementation of best practice construction techniques, there will be a negligible impact

on air quality from the Scheme.

Miscellaneous and Cumulative Impacts A number of other issues are commonly addressed within Environmental Impact Assessments. They include

impacts upon geology and soils (contamination, land stability and Geo-environmental designations) and land

use and have been included briefly in the ES for completeness. However, these factors were effectively

scoped out from further consideration at the scoping stage of the EIA process, by agreement with the three

affected Local Planning Authorities.

The majority of these assessments conclude a negligible impact. The impact on land use is considered to

be a minor adverse effect due to the temporary loss of agricultural land during construction and the

permanent loss of only a relatively small area (<5ha) of high quality agricultural land due to the construction

of the surface sites. The loss has been minimised and no farm businesses will be compromised.

Cumulative Development Impacts Analysis of coincident projects to be undertaken by Wessex Water within or near to the Scheme’s proposed

development area has confirmed that the timing and location of other planned projects will, where possible,

minimise coincidence of works with the installation of the proposed transfer main, thus not exacerbating the

environmental and amenity impacts predicted by the ES. The overall cumulative impact of development is

not considered to be significant.

Overall Overall, the scheme will have negligible impacts on contaminated land, ground stability and geo-

environmental designations and there are no significant cumulative impacts with other plans or projects.

There is a minor adverse effect on land use due to the permanent loss of a small area of agricultural land.



Conclusions In summary, the Scheme is required to enable Wessex Water to meet the following legal and regulatory

obligations:

The legal obligations in National Environment Programme issued by the Environment Agency,

specifically associated with reductions in the amount of water that Wessex Water can extract from

certain underground water sources from 2018 onwards, as required under the EU Habitats Directive;

The legally binding undertaking agreed with the Drinking Water Inspectorate, to ensure compliance

with Water Supply (Water Quality) Regulations 2000, associated with high levels of nitrates in certain

untreated water sources largely from agricultural fertiliser;

The regulatory outputs set by Ofwat, associated with the security of water supply to their customers

served by a single source of water only; and

The statutory duty to balance the supply of and demand for water up to the year 2035 as set out in the

Water Resources Management Plan approved by Defra in 2010.

The benefits of the Scheme include reduced abstractions from four existing underground water sources

leading to flow improvement in the Rivers Wylye and Bourne, the maintenance of drinking water quality for

140,000 water consumers, and the provision of a more secure water supply for 88,000 water consumers.

The Environmental Impact Assessment has reviewed potential impacts and concludes that the majority of

impacts are temporary during construction and of negligible or minor significance. Best practice site

construction techniques will minimise these impacts during construction.

Residual permanent impacts from the Scheme are limited to minor adverse impacts on ecology (from

washout discharges to watercourses), the historic environment and the landscape.

The permanent impacts on ecology can be managed through controlled use of the pipeline and storage tank

washouts. The temporary impacts on ecology can all be managed through suitable construction techniques,

habitat re-instatement and enhancement where possible. To further mitigate impacts Wessex Water

proposes to assist in the continued funding of the existing South Wiltshire Farmland Bird project covering the

area and to encourage the undertaking of enhancement works in habitats across the wider countryside.

The proposed above ground developments are considered to be of the scale and type which can be

accommodated with limited harm to the local and wider landscape setting. Subject to a high quality of

sensitive design and implementation of measures to enhance local biodiversity and visual amenity, the

landscape and visual impact of development can be minimised.

The impacts that have been identified on the historic environment will be managed through targeted

excavation and cataloguing at the four identified sites, along with careful routeing of the pipeline within the

50m planning corridor to accommodate unforeseen areas of archaeological significance.

There are major positive benefits from the Scheme in terms of a long term improvement in the security of

regional water supply and reduced groundwater abstractions for public supply, which will increase river flows

and help improve in-river ecology.

With measures in place to mitigate the temporary and permanent impacts, any adverse impacts identified as

a result of the Scheme are outweighed by the more widespread benefits from the provision of a reliable

water supply for the future and the improvements to river flows in the River Avon catchment.



Document Purchase Hard copies of the entire Environmental Statement and all associated appendices can be purchased from

Atkins.

Copies cost £350 each, inclusive of package and posting.

If you would like a copy, then please contact Atkins at the address shown below, enclosing a cheque made

payable to “Atkins Limited”:

Mark Jordan,

Atkins Limited,

Chilbrook Oasis Business Park, Eynsham, Oxford, Oxfordshire, OX29 4AH

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