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Poole Bay & Harbour Coastal Group POOLE BAY & HARBOUR STRATEGY STUDY Assessment of Flood and Coast Defence Options POOLE BAY

Halcrow Group Limited

Poole Bay & Harbour Coastal Group POOLE BAY & HARBOUR STRATEGY STUDY Assessment of Flood and Coast Defence Options POOLE BAY

Halcrow Group Limited

Halcrow Group Limited Burderop Park Swindon Wiltshire SN4 0QD Tel +44 (0)1793 812479 Fax +44 (0)1793 812089 www.halcrow.com

Halcrow Group Limited has prepared this report in accordance with the instructions of their client, Poole Bay & Harbour Coastal Group, for their sole and specific use. Any other persons who use any information contained herein do so at their own risk.

Halcrow Group Limited Burderop Park Swindon Wiltshire SN4 0QD Tel +44 (0)1793 812479 Fax +44 (0)1793 812089 www.halcrow.com

Poole Bay & Harbour Coastal Group POOLE BAY & HARBOUR STRATEGY STUDY Assessment of Flood and Coast Defence Options POOLE BAY

Contents Amendment Record This report has been issued and amended as follows:

Issue Revision Description Date Signed

0 1 Draft of Management 24 Oct 03 LSBanyard Unit PBY1 to Borough of Poole and Bournemouth Borough Council via ftp site

0 2 Draft to Coastal Group 6 Nov 03 LSBanyard via ftp site

1 0 Final to Borough of 28 Jan 04 LSBanyard Poole and Bournemouth Borough Council for Web Sites

Contents

1 Introduction 1 1.1 What is a Coastal Strategy? 1 1.2 How does this Coastal Strategy relate to the Shoreline Management Plan? 1

2 Strategic Overview 5 2.1 The Need for Beach Recharge 5 2.2 Availability of Beach Recharge 5 2.3 Effect of Beach Recharge 6 2.4 Effect of the Hengistbury Head Long Groyne 6 2.5 Consultation on the Desirable Erosion Rate of PBY2 and PBY3 7

3 Poole Bay 9 3.1 Sandbanks Ferry Slipway to Point House Café – PBY 1 9 3.2 Point House Café to Warren Hill – PBY 2 40 3.3 Warren Hill to Hengistbury Long Groyne – PBY 3 49

4 References 57

Figures

1.1 Relationship between Strategy Study and SMP 1.2 Poole Bay Management Units

3.1 Residual Life of Existing Timber Groynes 3.2 Example of Timber Groynes 3.3 Example of Rock Groynes 3.4 Example of Rock Offshore Breakwaters 3.5 Example of Geotextile Bag Breakwaters 3.6 Addition of Rock Groynes – Year 0 3.7 Addition of Rock Groynes – Year 10 3.8 Addition of Rock Groynes – Year 20 3.9 Addition of Offshore Reefs – Year 0 3.10 Addition of Offshore Reefs – Year 10 3.11 Addition of Offshore Reefs – Year 20 3.12 Erosion Risk Areas

3.13 Shoreline Change 1978 – 2002 3.14 Location of Cross Sections – 3d view looking towards Hengistbury Head 3.15 Cross Section of Peninsular at Double Dykes 3.16 Location of Greatest Erosion between 1978 and 2002

1 Introduction

1.1 What is a Coastal Strategy? This document is part of the Poole Bay & Harbour Strategy, which defines methods by which coastal defence of the Hengistbury Head to Durlston Head (including Poole Harbour) should be managed in the next 50 years. The strategy builds on the work of the Poole and Christchurch Bays Shoreline Management Plan (SMP) Halcrow (1999)

1.2 How does this Coastal Strategy relate to the Shoreline Management Plan? The existing SMP defines the shoreline alignment policy (whether the existing alignment should be held, realigned or moved forward; or whether there should be only limited intervention or no action at all.)

The current study is not an SMP, but it develops the SMP policies by appraising ways of implementing them. The range of strategic options will vary according to the section of coastline under consideration.

The relationship between the SMP, Coastal Strategy and Scheme Development is shown in Figure 1.1.

Figure 1.1 Relationship between Strategy Study and SMP

The shoreline of Poole Bay has been divided into a number of management units, as shown in Figure 1.2:

• PBY1 – North Haven Point (Sandbanks) to Point House Café (Southbourne)

• PBY2 - Point House Café (Southbourne) to Double Dykes

• PBY3 – Double Dykes to Hengistbury Head Long Groyne

Figure 1.2 Poole Bay Management Units

This map is reproduced from the Ordnance Survey mapping with the permission of the Controller of Her Majesty’s Stationery Office (c) Crown copyright. All rights reserved. Unauthorised reproduction infringes Crown Copyright and may lead to prosecution of Civil proceedings. Bournemouth Borough Council. Licence no LA077232.2003

In developing the Strategy for Poole Bay, a wide range of studies have been undertaken. The following provides a brief summary of those parts of the study that are of relevance to the PBY frontage.

• Technical Annex 1 – Coastal Conditions – the coastal conditions affecting the shoreline have been assessed through modelling and calculations of wave conditions, extreme water levels, tidal cycles and joint probability between waves and water levels.

• Technical Annex 2 – Beach Modelling – modelling of wave and water levels has been used to drive models of longshore and cross-shore sediment transport. In particular the degree of beach draw-down under storm conditions has bee modelled to assess the degree of beach protection required along the frontage. The performance of different types of beach control structure (groynes and breakwaters) has been evaluated using calibrated models of the beach movement.

• Technical Annex 3 – Shoreline Evolution – the location of the shoreline between Point House Café and Hengistbury Head Long Groyne (Management Units PBY2 & PBY3 in Figure 1.2) in 1978 and 2001 has been compared using geo-rectified aerial photographs. This method provides a more accurate comparison than the use of Ordnance Survey Mapping or conventional aerial photographs. The geo-rectified photographs were “stretched” electronically to fit the 2001 Ordnance Survey Landline (electronic mapping) and the uncertainties in the method calculated.

• Technical Annex 5 – Coastal Processes – the sources of supply, movement and output of sediment within Poole Bay were identified using the computer modelling described in Technical Annex 2 and in HR Wallingford 2003 (tidal and wave modelling carried out for this Strategy Study). Where possible, the volumes of sediment movement were evaluated (with the measurement in cubic metres per year - m3/year). This information is essential to the assessment of why a particular shoreline may be eroding or accreting and in judging what the affect of any intervention on the coast may have.

• Technical Annex 7 – Implications of Climate Change – the potential effects of the following factors associated with climate change have been evaluated and the potential implications for each management unit of the shoreline have been assessed: (i) changes in sea level, incorporating global (eustatic) sea level rise and land-level (isostatic) change (ii) changes in storm surge, due to changes in extremes of barometric pressure and wind stress caused by changing weather patterns (iii) changes in wind climate affecting the height, periods and directions of wave conditions (iv) changes in rainfall intensities, durations, and event frequencies, particularly affecting cliff slippage and run-off flooding

• Technical Annex 8 – Flood and Coast Defence Benefits and Costs – the benefits and costs of strategy options have been estimated and presented in this report. Further details are included in Technical Annex 8.

• Technical Annex 9 – Sources of Beach Recharge – potential sources of marine aggregates for beach recharge have been identified and alternative sources have been briefly described.

• Technical Annex 10 – Strategic Environmental Assessment (SEA) – This document contains the background data on which the Strategic Environmental Assessment is based (known as the baseline), which describes how the environmental objectives of the Strategy have been selected. Each of the options in the Strategy are then compared against these objectives to assess their environmental implications.

2 Strategic Overview

2.1 The Need for Beach Recharge The on-going need for beach recharge was identified in the SMP. Work carried out to assess the inputs, transport and output of sediment along the whole Poole Bay frontage (Technical Annex 5) confirms that, with the exception of Sandbanks, the potential for sediment loss from this frontage is considerably greater than the potential for sediment gain. This situation arises primarily from the cessation of erosion that resulted from the construction of seawalls along the frontage over the course of the last century. The alternative course of action to beach recharge would be demolition of the seawalls and of the properties that they protect. This was considered and rejected by the SMP.

2.2 Availability of Beach Recharge The availability of sand for beach recharge is described in more depth in Technical Annex 9. It is limited at present to:

• Swash Channel and Middle Ship Channel (Entrance to Poole Harbour) – this could potentially supply 100,000m3 of suitable materials every 2 years through maintenance dredging • Swash Channel and Middle Ship Channel (Entrance to Poole Harbour) – this could potentially supply 1,000,000m3 (as a “one-off” supply) of suitable materials if a deepening of the shipping channels were to proceed • Licensed dredging sites located to the south-east and south-west of the Isle of Wight – these sites could provide suitable materials, but the costs would be higher than from the Swash Channel & Middle Shipping Channel since screening (large scale sieving) of the sediment would be required • For future recharges after 10 years, it is possible that a suitable materials might be available from a prospective licensed site at Dolphin Sand. A licence is being sought by a commercial aggregates company for the site. This is expected to hold suitable sediment which would not require screening and would be considerably closer than the alternative licensed sites.

2.3 Effect of Beach Recharge Sections of the beach in the PBY 1 have been recharged since 1970; more details of the past campaigns are given in Technical Annex 9. Since the predominant direction of longshore transport over much of the PBY1 frontage is from west to east, the recharge gradually feeds the beaches to the east, namely the Point House Café to Hengistbury Head frontage (PBY2 & PBY3) and beyond into Christchurch Bay (Technical Annex 5).

The feed of sediment to the adjacent shoreline will depend on the on-going beach recharge, but also on the efficiency of the beach control structures that are selected for the PBY1 frontage. If the rate of longshore transport along PBY1 were to be reduced considerably, this could have a detrimental effect on the PBY2 and PBY3 frontages. Over the period of 30 years 1970-2000 a total of 1,885,916m3 has been placed within this management unit. This means that a future recharge over the 50 year Strategy Period of some 3,000,000m3 will be required to avoid an acceleration of the existing rate of erosion in downdrift areas (management units PBY2 and PBY3).

2.4 Effect of the Hengistbury Head Long Groyne Since construction of the Hengistbury Head Long Groyne in 1938, the beach has shown a net accretion immediately to the west (although the affects of seasonal variation and storm events may have caused temporary erosion, the beach has subsequently recovered). The comparison of aerial photographs shows that the cliffline over a length of 500m to the west of the Long Groyne has not eroded due to wave action for the past 24 years (since 1978). Along the 300m immediately to the west of the Long Groyne this has resulted in the growth of sand dunes.

The protection of the cliff at the headland is essential for avoiding long-term erosion throughout Poole Bay and Christchurch Bay. If the Long Groyne were to become dilapidated or to be removed, the beach width would reduce and the cliff would start to erode at the headland. Subsequently, following the equilibrium bay principle of Silvester & Hsu (1993), the position of both bays would be subject to increased erosion as the shoreline would seek a position further landwards. Whilst the direct influence of the Long Groyne in stopping cliff erosion has been limited to the shoreline 500m to the west, the indirect result is a reduction in shoreline erosion extending possibly as far west as Branksome Dene and as far east as Milford on Sea.

2.5 Consultation on the Desirable Erosion Rate of PBY2 and PBY3 A meeting to discuss the problems of coast protection and possible options of was organised by Halcrow and held at Hengistbury Head Centre on 15 May 2003 between:

• English Nature • English Heritage • Dorset Regionally Important Geological Sites (RIGS) • Dorset County Council Archaeological Section • Hengistbury Head Centre • Bournemouth Borough Council • Christchurch Borough Council • New Forest District Council

(with observers from Bournemouth University and University of East Anglia and apologies from Dorset Geologist’s Association)

The work provided in Technical Annex 3 was presented at the meeting, and it was confirmed that two factors were not in question, since they are both integral to the Hold the Line policy of PBY1:

• beach recharge at Bournemouth/Southbourne would continue • the long groyne would not be removed

The consensus of the meeting, as recorded in minutes copied to all attendees on the 27 May, was:

(a) existing management practices to continue, to allow the existing rate of erosion to occur at Hengistbury Head.

(b) Halcrow to investigate and evaluate the probability of a full breach of the neck of land between Point House Café and Hengistbury Head, concentrating on: (i) the area to the east of Double Dykes, and (ii) the area known as White Pits. Should works be required English Nature has less concern over the conditions of the cliffs in this area compared to the high cliffs along the Hengistbury Head section as they are outside the designated GCR site,

though they are still of geological interest and consultation would be needed.

(c) monitoring through ortho-rectified photos to continue in future years though the Regional Monitoring initiative (being managed, by amongst others, New Forest District Council)

(d) English Heritage to investigate archaeology monitoring/excavations in the future prior to future cliff collapse, to allow records to be made

3 Poole Bay

3.1 Sandbanks Ferry Slipway to Point House Café – PBY 1

This map is based upon the Ordnance Survey mapping with the permission of the Controller of Her Majesty’s Stationery Office (c) Crown Copyright. All rights reserved. Unauthorised reproduction infringes Crown Copyright and map lead to prosecution or civil proceedings. Bournemouth Borough Council Licence No LA077232.2003

3.1.1 Existing Shoreline & Defences The shoreline comprise a sandy beach, with some shingle towards the eastern end, with seawalls behind. Between Poole Head and Point House Café the seawalls protect the toe of the cliffs that are no longer eroding due to wave action. From Sandbanks to Poole Head, the area behind the seawalls is low lying with some dunes. The beach is controlled by a number of different structures, principally

rock groynes (at Sandbanks), timber groynes and concrete groynes (west of Boscombe Pier)

The rock groynes at Sandbanks and at Solent Beach are expected to continue to perform adequately for the duration of the Strategy Period of 50 years.

The timber groynes (and the two concrete groynes) are expected to require replacement during the Strategy Period. The timing of the need for replacement is measured by the “residual life” of the structures. On the basis that hardwood timber structures in the marine environment will typically last for 25 years, the residual life of the existing timber groynes is shown in Figure 3.1. The existing strategy over past decades has been to replace between 2 and 5 groynes every winter.

Details of environmental issues, designations and objectives are provided in Technical Annex 10.

3.1.2 Flood and Coast Defence Problem The standard of coast protection at the frontage depends considerably on the level and width of the beach.

Computer modelling of the beach response under storm conditions (Technical Annex 2) shows that:

• the beach can be eroded by 7m under a 1:1 year condition (a condition that has 63% probability of occurring in any year) • the beach can be eroded by 12m under a 1:10 year condition (a condition that has 10% probability of occurring in any year) • the beach can be eroded by 17m under a 1:100 year condition (a condition that has 1% probability of occurring in any year) • collapses of the seawall at the Southbourne Zig-Zag in 1988 and again 1989 (Technical Annex 2) occurred under storm conditions that were less severe than a 1:1 year storm - the principal contributing factor was not the severity of the storm, but was the narrowness of the beach prior to the event

The assessment of Coastal Processes (Technical Annex 5) shows that:

• there is considerable onshore feed of sediment from Hook Sand to Sandbanks driven primarily by flood tidal currents into Poole Harbour, but also by wave action, particularly under south-easterly storms • the primary movement of sediment along the Sandbanks frontage is from east to west, primarily due to flood tide currents • to the east of Sandbanks (that is, to the east of the existing rock groyne scheme) the movement of sediment is primarily from west to east driven by wave action – the rate of transport increases from west to east

On the basis of these findings:

(a) the existing rock groynes at Sandbanks are sufficient to allow continued trapping of on-shore sediment movement (b) the existing beach at Sandbanks is sufficiently wide to provide a 1:100 year standard of protection and is not expected to require further recharge (c) the existing beach between Sandbanks and Canford Cliffs that was recharged in February March 2003 is sufficiently wide to provide a 1:100 year standard of protection, but is expected to require further recharge in future as the natural feed of sediment to this section is small (d) the existing beach between Canford Cliffs and Point House Café is not sufficiently wide to provide a 1:100 year standard of protection – the current standard is judged to be between 1:1 year and 1:10 year depending on the beach width at any particular location

3.1.3 Current SMP Policy (adopted 1999) Hold the Existing Line both in the Short Term and in the Long Term. The findings in Section 3.1.2 confirm the SMP policy that beach recharge is required to Hold the Line.

3.1.4 Strategic Options The principal decisions to be taken at Strategy Stage is the form of beach control structures and timing and placement of the recharge.

The following forms of beach control have been identified:

• Open Beach Recharge (no beach control structures) • Timber Groynes • Rock Groynes • Rock Offshore Breakwaters • Geotextile Bag Offshore Breakwaters

Generic examples of timber groynes, rock groynes, rock breakwaters and geotextile reef breakwaters are given in Figures 3.2 to 3.5.

Since many of the existing timber groynes along the PBY1 frontage were only recently constructed and therefore have a considerable residual life, it is not reasonable when considering other forms of control structure to replace all of the groynes immediately.

On the basis of Figure 3.1, the groyne field has been classified in 3 groups:

• Groynes that are already at the end of their residual life – this includes the 23No Borough of Poole groynes from the end of the 2001 rock groyne scheme to Branksome Dene and the 2No Bournemouth Borough Council groynes immediately to the east of Point House Café

• Groynes that will be at the end of their residual life by 2014 – this includes most of the groynes to the east of Boscombe Pier up to the rock groynes at Solent Beach

• Groynes that will be at the end of their residual life by 2024 – this includes most of the groynes to the west of Boscombe Pier up to Branksome Dene

The Strategic Options that have been considered are given in the following tables: Table 3.1 - . For the Rock Groynes options, Figures 3.6 – 3.8 illustrate how the transition from timber groynes might be achieved For the Offshore Breakwater options, Figures 3.9 – 3.11 illustrate how the transition from timber groynes might be achieved. To allow a transition between the PBY1 and PBY2 frontage, each option includes the replacement of the 4 timber groynes at the west end of PBY2.

Strategic Option Description No Active No action taken apart from fulfilling H&S requirements Intervention Table 3.1

Strategic Option Description Minimum Since Beach Recharge is essential to management of the frontage, it has not been Maintenance possible to devise a “minimum maintenance” option. Option Hold the Line B (Timber Groynes) (Table 3.4) is the closest approximation to this option.

Table 3.2

Strategic Option Description Hold the Line A - Open Beach This option would include:

Recharge: (a) the dredging of sand of a similar grading to the existing beach from either the Swash Channel entrance to Poole Harbour or a licensed dredging site (b) pumping ashore of the sand from the dredger through a pipeline (either floating or sunken, depending on the contractor’s preferred plant and methods) (c) transportation of the sand along the beach either through the pipeline or by dumper truck (d) active monitoring and recycling of sediment levels on the beach (e) initial placement of 370,000m3 of sand by bulldozer to a similar slope gradient as the existing beach (f) subsequent recharges of approximately 500,000m3 anticipated to be required every 2 years. (g) allowing deterioration of the existing timber groynes (h) removal of timber groynes at the end of their residual life (i) maintaining the Hengistbury Head Long Groyne

Table 3.3

The following scenarios have been developed to test the sensitivity of the cost of this option:

• A1 – assuming that capital dredging of the Swash Channel is carried out and that this material is available for use in year 0 of the scheme • A2 – assuming capital dredging of the Swash Channel does not occur • A3 – assuming a 50% decrease in the volume of recharge required for subsequent beach recharge (indicating a measure of the uncertainty in managing an open beach) • A4 - assuming a 50% increase in the volume of recharge required for subsequent beach recharge (indicating a measure of the uncertainty in managing an open beach)

Strategic Option Description Hold the Line B – This option would include: Timber Groynes, 2 yearly recharge (a) –(d) as Open Beach Recharge 3 (Rock Groynes at (e) initial placement of 860,000m of sand by bulldozer to a similar slope gradient as Sandbanks) the existing beach (f) subsequent recharges of approximately 430,000m3 anticipated to be required every 2 years. (g) allowing deterioration of the existing timber groynes (h) in Year 2004: • removal of 21No timber groynes between Sandbanks and Branksome Dene and 2No at Solent Beach • construction of 18No 70m long timber groynes between Sandbanks to Branksome Dene and 2No at Solent Beach (i) from 2005, continuing programme of removal and replacement of 3No groynes per year allowing replacement of all 75No timber groynes between Sandbanks and Solent Beach on a 25 year programme (j) maintaining the Hengistbury Head Long Groyne

Table 3.4

The following scenarios have been developed to test the sensitivity of the cost of this option:

• B1 – assuming that capital dredging of the Swash Channel is carried out and that this material is available for use in year 0 of the scheme • B2 – assuming capital dredging of the Swash Channel does not occur

Strategic Option Description Hold the Line C – Timber Groynes, This option would include: 10-yearly recharge (Rock Groynes at (a)–(d) as Open Beach Recharge Sandbanks) (e) initial placement of 1,730,000m3 of sand by bulldozer to a similar slope gradient as the existing beach (f) subsequent recharges of approximately 1,730,000m3 anticipated to be required every 10 years. (g) allowing deterioration of the existing timber groynes (h) in Year 2004: • removal of 21No timber groynes between Sandbanks and Branksome Dene and 4No at Solent Beach • construction of 18No 70m long timber groynes between Sandbanks to Branksome Dene and 2No at Solent Beach (i) from 2005, continuing programme of removal and replacement of 3No groynes per year allowing replacement of all 75No timber groynes between Sandbanks and Solent Beach on a 25 year programme (j) maintaining the Hengistbury Head Long Groyne

Table 3.5

The following scenarios have been developed to test the sensitivity of the cost of this option:

• C1 – assuming that capital dredging of the Swash Channel is carried out and that this material is available for use in year 0 of the scheme • C2 – assuming capital dredging of the Swash Channel does not occur

Strategic Option Description

Strategic Option Description Hold the Line D – This option would include: 100m Rock Groynes (a)–(d) as Open Beach Recharge and 2 yearly Beach (e) initial placement of 580,000m3 of sand by bulldozer to a similar slope gradient as Recharge the existing beach (f) subsequent recharges of approximately 200,000m3 anticipated to be required every 2 years, decreasing to approximately 70,000m3 and 50,000m3 every 2 years after year 10 and 20, respectively. (g) allowing deterioration of the existing timber groynes (h) in Year 2004: • removal of 21No timber groynes between Sandbanks and Branksome Dene and 4No at Solent Beach • construction of 15No 100m long (200m spacing) rock groynes between Sandbanks to Branksome Dene and 3No at Solent Beach (i) in Year 2014: • removal of 4No timber groynes between Branksome Dene and Alum Chine and 25No between Boscombe Pier and Point House Cafe • construction of 2No 100m long (200m spacing) rock groynes between Branksome Dene and Alum Chine and 17No between Boscombe Pier and Point House Cafe (j) in Year 2024: • removal of 18No timber groynes between Alum Chine and Boscombe Pier • construction of 18No 100m long (200m spacing) rock groynes between Alum Chine and Boscombe Pier (k) maintaining the Hengistbury Head Long Groyne

Table 3.6

The following scenarios have been developed to test the sensitivity of the cost of this option: • D1 – assuming that capital dredging of the Swash Channel is carried out and that this material is available for use in year 0 of the scheme • D2 – assuming capital dredging of the Swash Channel does not occur

Strategic Option Description Hold the Line E – This option would include: 100mRock (a)–(d) as Open Beach Recharge Groynes and 10 e) initial placement of 820,000m3 of sand by bulldozer to a similar slope gradient as yearly Beach the existing beach Recharge f) subsequent recharge of approximately 320,000m3 anticipated to be required after 10 years, decreasing to approximately 245,000m3 every 10 years after year 20. (g) allowing deterioration of the existing timber groynes (h) in Year 2004: • removal of 21No timber groynes between Sandbanks and Branksome Dene and 4No at Solent Beach • construction of 15No 100m long (200m spacing) rock groynes between Sandbanks to Branksome Dene and 3No at Solent Beach (i) in Year 2014: • removal of 4No timber groynes between Branksome Dene and Alum Chine and 25No between Boscombe Pier and Point House Cafe • construction of 2No 100m long (200m spacing) rock groynes between Branksome Dene and Alum Chine and 17No between Boscombe Pier and Point House Cafe (j) in Year 2024: • removal of 18No timber groynes between Alum Chine and Boscombe Pier • construction of 18No 100m long (200m spacing) rock groynes between Alum Chine and Boscombe Pier (k) maintaining the Hengistbury Head Long Groyne

Table 3.7

The following scenarios have been developed to test the sensitivity of the cost of this option: • E1 – assuming that capital dredging of the Swash Channel is carried out and that this material is available for use in year 0 of the scheme • E2 – assuming capital dredging of the Swash Channel does not occur

Strategic Option Description Hold the Line F – This option would include: 150m Rock Groynes (a)–(d) as Open Beach Recharge and 2 yearly Beach (e) initial placement of 530,000m3 of sand by bulldozer to a similar slope gradient as Recharge the existing beach (f) subsequent recharges of approximately 200,000m3 anticipated to be required every 2 years, decreasing to approximately 70,000m3 and 80,000m3 every 2 years after year 10 and 20, respectively. (g) allowing deterioration of the existing timber groynes (h) in Year 2004: • removal of 21No timber groynes between Sandbanks and Branksome Dene and 4No at Solent Beach • construction of 7No 150m long (450m spacing) rock groynes between Sandbanks to Branksome Dene and 2No at Solent Beach (i) in Year 2014: • removal of 4No timber groynes between Branksome Dene and Alum Chine and 25No between Boscombe Pier and Point House Cafe • construction of 1No 150m long (450m spacing) rock groynes between Branksome Dene and Alum Chine and 8No at Boscombe Pier and Point House Cafe (j) in Year 2024: • removal of 18No timber groynes between Alum Chine and Boscombe Pier • construction of 8No 150m long (450m spacing) rock groynes between Alum Chine and Boscombe Pier (k) maintaining the Hengistbury Head Long Groyne

Table 3.8

The following scenarios have been developed to test the sensitivity of the cost of this option:

• F1 – assuming that capital dredging of the Swash Channel is carried out and that this material is available for use in year 0 of the scheme • F2 – assuming capital dredging of the Swash Channel does not occur • F3 – based on previous construction costs from the Sandbanks Groynes (& assuming that capital dredging of the Swash Channel is carried out and that this material is available for use in year 0 of the scheme) • F4 - based on previous construction costs from the Sandbanks Groynes (& assuming capital dredging of the Swash Channel does not occur)

Strategic Option Description Hold the Line G – This option would include: 150mRock Groynes (a)–(d) as Open Beach Recharge and 10 yearly Beach (e) initial placement of 800,000m3 of sand by bulldozer to a similar slope gradient as Recharge the existing beach (f) subsequent recharges of approximately 330,000m3 anticipated to be required after year 10, thereafter approximately 400,000m3 required every 10 years (g) allowing deterioration of the existing timber groynes (h) in Year 2004: • removal of 21No timber groynes between Sandbanks and Branksome Dene and 4No at Solent Beach • construction of 7No 150m long (450m spacing) rock groynes between Sandbanks to Branksome Dene and 2No at Solent Beach (i) in Year 2014: • removal of 4No timber groynes between Branksome Dene and Alum Chine and 25No between Boscombe Pier and Point House Cafe • construction of 1No 150m long (450m spacing) rock groynes between Branksome Dene and Alum Chine and 8No between Boscombe Pier and Point House Cafe (j) in Year 2024: • removal of 18No timber groynes between Alum Chine and Boscombe Pier • construction of 8No 150m long (450m spacing) rock groynes between Alum Chine and Boscombe Pier (k) maintaining the Hengistbury Head Long Groyne

Table 3.9

The following scenarios have been developed to test the sensitivity of the cost of this option: • G1 – assuming that capital dredging of the Swash Channel is carried out and that this material is available for use in year 0 of the scheme • G2 – assuming capital dredging of the Swash Channel does not occur • G3 – based on previous construction costs from the Sandbanks Groynes (& assuming that capital dredging of the Swash Channel is carried out and that this material is available for use in year 0 of the scheme) • G4 - based on previous construction costs from the Sandbanks Groynes (& assuming capital dredging of the Swash Channel does not occur)

Strategic Option Description Hold the Line H – This option would include: Rock Offshore (a)–(d) as Open Beach Recharge Breakwaters and (e) initial placement of 1,640,000m3 of sand by bulldozer to a similar slope gradient Beach Recharge as the existing beach (f) subsequent recharge of approximately 800,000m3 anticipated to be required after 10 years, decreasing to approximately 670,000m3 every 10 years after year 20. (g) allowing deterioration of the existing timber groynes (h) in Year 2004: • removal of 21No timber groynes between Sandbanks and Branksome Dene and 4No at Solent Beach • construction of 7No 100m long (300m spacing) rock breakwaters between Sandbanks to Branksome Dene and 2No rock groynes at Solent Beach (i) in Year 2014: • removal of 4No timber groynes between Branksome Dene and Alum Chine and 25No between Boscombe Pier and Point House Cafe • construction of 9No 100m long (300m spacing) rock breakwaters between Boscombe Pier and Point House Cafe (j) in Year 2024: • removal of 18No timber groynes between Alum Chine and Boscombe Pier • construction of 8No 100m long (300m spacing) rock breakwaters between Alum Chine and Boscombe Pier (k) maintaining the Hengistbury Head Long Groyne

Table 3.10

The following scenarios have been developed to test the sensitivity of the cost of this option:

• H1 – assuming that capital dredging of the Swash Channel is carried out and that this material is available for use in year 0 of the scheme • H2 – assuming capital dredging of the Swash Channel does not occur • H3 – assuming that the design of the structures could be refined such that the degree of sand loss from the beach under the 150m rock groyne options could be matched (this provides the minimum recharge requirement to ensure that Hengistbury Head and Christchurch Bay continues to receive the past rate of sediment supply) – 2 yearly recharge

• H4 – assuming that the design of the structures could be refined such that the degree of sand loss from the beach under the 150m rock groyne options could be matched (this provides the minimum recharge requirement to ensure that Hengistbury Head and Christchurch Bay continues to receive the past rate of sediment supply) – 10 yearly recharge

Strategic Option Description Hold the Line I – This option would include: Geotextile Bag (a)–(d) as Open Beach Recharge Breakwaters and (g) initial placement of 1,640,000m3 of sand by bulldozer to a similar slope gradient Beach Recharge as the existing beach (e) subsequent recharge of approximately 800,000m3 anticipated to be required after 10 years, decreasing to approximately 670,000m3 every 10 years after year 20. (g) allowing deterioration of the existing timber groynes (h) in Year 2004: • removal of 21No timber groynes between Sandbanks and Branksome Dene and 4No at Solent Beach • construction of 7No 100m long (300m spacing) geotextile reefs between Sandbanks to Branksome Dene and 2No rock groynes at Solent Beach (i) in Year 2014: • removal of 4No timber groynes between Branksome Dene and Alum Chine and 25No between Boscombe Pier and Point House Cafe • construction of 9No 100m long (300m spacing) geotextile reefs between Boscombe Pier and Point House Cafe (j) in Year 2024: • removal of 18No timber groynes between Alum Chine and Boscombe Pier • construction of 9No 100m long (300m spacing) geotextile reefs between Alum Chine and Boscombe Pier (k) from Year 2024: • renewal of 50% of geotextile bags as they come to the end of their design life of 20 years. (l) maintaining the Hengistbury Head Long Groyne

Table 3.11

The following scenarios have been developed to test the sensitivity of the cost of this option:

• I1 – assuming that capital dredging of the Swash Channel is carried out and that this material is available for use in year 0 of the scheme & that, due to deterioration of the geotextile, 50% of the bags will need to be replaced after 20 years (in line with Naue Fasertechnik’s guidance)

• I2 – assuming that capital dredging of the Swash Channel is carried out and that this material is available for use in year 0 of the scheme & that, due to deterioration of the geotextile, 100% of the bags will need to be replaced after 20 years (in line with Naue Fasertechnik’s guidance) • I3 – assuming that the design of the structures could be refined such that the degree of sand loss from the beach under the 150m rock groyne options could be matched (this provides the minimum recharge requirement to ensure that Hengistbury Head and Christchurch Bay continues to receive the past rate of sediment supply) – 2 yearly recharge • I4 – assuming that the design of the structures could be refined such that the degree of sand loss from the beach under the 150m rock groyne options could be matched (this provides the minimum recharge requirement to ensure that Hengistbury Head and Christchurch Bay continues to receive the past rate of sediment supply) – 10 yearly recharge • I5 – as I1, but assuming capital dredging of the Swash Channel does not occur • I6 – as I2, but assuming capital dredging of the Swash Channel does not occur

3.1.5 Strategic Environmental Assessment The specific objectives for this area have been established as part of the Strategic Environmental Assessment (see Technical Annex 10, Table 5.2). These have been summarised in Table 2.1.1.

All intervention options would meet the environmental objectives of avoiding interference with the earth science and nature conservation value, protecting properties and maintaining recreational resources.

Provided intervention is implemented through beach recharge and maintaining/installing suitable beach control structures, then works can be implemented in a manner that holds the line whilst minimising the effects on earth science and nature conservation, provided that additional sea walls are not constructed where there are currently none.

3.1.6 Additional Environmental Factors In addition to the Specific Environmental Objectives, which relate primarily to environmental designations there are a number of additional environmental factors that need to be considered relating to the choice of control structure. The selection of the form of scheme may be based on other factors such as (in alphabetical order) aesthetics, amenity, buildability, environmental sustainability, local economy benefits, maintenance, material sourcing and public safety. Conclusions relating to each issue are provided in italics at the end of each section.

(a) Aesthetics The visual impact of control structures is very much a personal preference.

As there are timber groynes within the frontage at present it is likely that the use of timber in a new scheme will be considered the least visually intrusive option. Timber groynes are generally considered to be a traditional part of the English urban seascape, but the “tradition” extends only over the past 150 years. This however, would most likely also be true of rock groynes if their use had been as common.

Where there have been no existing structures, the use of rock groynes with low crest levels can be less visually intrusive than timber groynes, depending particularly on the colour of the rock used. The Portland stone used at Sandbanks and on the east side of Hengistbury Head is pale in colour and therefore less intrusive than igneous rocks such as Larvikite and Granite. However, those parts of the structures below the high tide will tend to accumulate seaweed, which will rapidly change the colour of the structures from pale brown to dark green.

The use of offshore rock breakwaters would be more visually intrusive than the use of other types of control structure, since they would be located to seaward of the beach. Geotextile bag breakwaters would have a lower crest level than rock breakwaters and, would therefore be less obtrusive.

When comparing the change in visual appearance of the beach, the continued use of timber groynes would be less visually intrusive. When comparing the absolute visual intrusion of the all forms of construction, it is considered than rock groynes and offshore geotextile bag breakwaters would be less visually intrusive, provided that the crest lines are kept to a low level.

(b) Amenity As with visual intrusion, this factor is subjective. Some members of the public appreciate the presence of timber groynes for various reasons such as their use as a wind-break, clothes airer etc and as they serve to restrict the wandering of small children.

As rock groynes have a larger footprint than timber groynes a certain reduction in the amount of beach available for use by the general public is expected. However, if the groynes were constructed to allow the beach crest to cover the trunk this would be of lesser concern.

The use of rock breakwaters and geotextile breakwaters would increase the amenity area of the beach, since these structures would be located offshore.

Rock breakwaters and geotextile bag breakwaters would increase the amenity area of the beach, and from this perspective are preferred. It is difficult to provide an objective recommendation when comparing timber and rock groynes only.

(c) Buildability The construction of timber groynes tends to be more limited by tidal levels than rock groynes. The construction of the existing timber groynes has historically required the installation of temporary piers to assist with the piling, although the latest construction method of winter 2003/4 has avoided this.

At present there is no reason to believe that the ground conditions are unfavourable for piling (for timber groynes) and navigational access for barges for construction of rock groynes, rock breakwaters and geotextile bag breakwaters appears to be available within the tidal limits. With access to the beach via the promenade along a large section of the frontage, there is little obstruction to importing materials by road.

A further issue associated with piling for the timber groynes concerns noise levels. The driving of piles can cause noise pollution unless ‘silent piles’ or ‘quiet piling’ equipment is used. There would be considerably less noise disturbance involved in the construction of rock groynes, rock breakwaters and geotextile bag breakwaters, although offloading of rock barges is not usually restricted to daylight hours. Evidence from previous projects suggests that complaints are more likely to be received during night work.

The construction of rock groynes is expected on balance to be easier to achieve than the other options. However, the selection of a competent contractor, experienced in coastal construction is of overriding importance. Noise disturbance during construction is likely to be greater during construction of timber groynes, but this has been accepted along much of the Bournemouth frontage over the past decades without difficulty.

(d) Environmental Sustainability Sustainability is difficult to quantify, but has been assessed in a comprehensive way using the methods detailed in “Sustainable use of new and recycled materials in coastal and fluvial construction; A Guidance Manual”. Alternative construction materials, sources and methods have been assessed in terms of a number of sustainability themes; Environment, Economy and Social, sub-themes; Global, Local and Internal and sub-issues. These sub-issues have each been weighted and a point system, “Ecopoints” devised. The system was devised by Building Research Establishment over three years and incorporates the views and expertise of many different individuals and organisations from both the private and public sectors. The Ecopoints method has been released as a spreadsheet estimator with the publication.

Suitable volumes of both rock and timber for a typical scheme were input into the Environmental Estimator spreadsheet along with the mode and distance of transportation. The Estimator produces a value of transportation energy (in GigaJoules - GJ) and also an environmental score in Ecopoints.

Assuming hardwood timber from Guyana and rock from a Portland quarry, both imported by sea, the transportation of the timber requires twice as much energy as that required for the rock groyne option.

When comparing equal volumes of rock and timber for this scheme, the environmental sustainability (scored in Ecopoints) of the use of rock is considered to be 10 times better. However, when taking into account the material volumes, the sustainability of the timber groyne option is 5 times better. This result is solely a reflection of the material volumes required for each (the rock option uses 50 times more material than the timber option).

Based on the comprehensive view of sustainability incorporated into the method (which balances many environmental impacts, rather than any single issue), the use of timber groynes is found to be more sustainable, solely because the volume of material is approximately 50 times less than that required for rock groynes.

(e) Local Economy Benefit It is expected that suitable rock can be obtained from Portland (although larger rock may also be required from other sources within the UK, such as the Mendips or potentially from outside the UK). The use of local resources would provide a market for quarries within Dorset and consequently would increase income to the regional economy.

Geotextiles of the construction of bag breakwaters would be manufactured in either England or in Continental Europe, although there are no manufacturers in Dorset. It is not known whether there are any suitable local timber sources available although it is suspected unlikely.

The use of rock groynes would be expected to be more beneficial to the local economy.

(f) Maintenance Structures on the shoreline at this frontage are exposed to wave action and to abrasion from sediments entrained by the waves.

Timber groynes have a life span of only 25 years, planks have to be replaced regularly and annual maintenance is required. The lifespan of Geotextile Bags is not known, as this form of construction is new to locations exposed to the degree of wave action that occurs at this frontage, but is estimated by manufacturers to be about 20 years. In addition, the use of geotextile bag breakwaters by surfers may also cause damage to the bags. The form of construction of a geotextile bag reef allows for the clearance of deteriorated bags and the placement of additional bags. Following discussion with geotextile manufacturer Naue Fasertechnik, it has been assumed that 50% of the bags would be required to be replaced after 20 years.

Rock groynes however should not require any maintenance over the 50-year design life and any minor movements should serve to lock the rocks in place. Maintenance and repair of rock groynes should only be required following storms in excess of the design standard.

Rock groynes and rock breakwaters will require less maintenance than timber or geotextile structures

(g) Material Sources The choice of wood for constructing timber groynes can be controversial and is considered here as a separate issue from overall environmental sustainability.

Hardwoods are generally preferred due to their durability in the maritime environment. Foreign species like Greenheart and Purpleheart from Guyana often take prevalence over other tropical hardwoods and over locally sourced oak. In the case of Greenheart and Purpleheart, the Forestry Stewardship Council FSC do not certify Guyana’s timber. However, Guyana’s government is committed to a policy of sustainable development and this is endorsed by the Guyana Forestry Commission and by the formation of the Guyana Environmental Protection Agency. Further details on the sourcing and environmental sustainability of timber is provided in the enclosed report “Assessment of Alternative Timbers for Groyne Replacement”.

The use of recycled timber is an option. This was pursued by Southend Borough Council for the construction of their Flood Defence Improvements in 2002. However, despite considerable efforts being made to obtain suitable recycled timber, new timber was required for the piling works due to size and strength issues.

Geotextiles and rock (aggregates) are used in considerable quantities in other forms of civil engineering, meaning that the use of additional materials for coast protection would represent a insignificant increase in use of such resources.

On balance, when considering the source of the material only, the use of rock and geotextiles tends to be less controversial than the use of hardwood timber.

(h) Public Safety – Trip Hazards Exposed rock is generally perceived to be unsafe due to the temptation to walk or climb on the structure and the risk of tripping or slipping. As the rocks chosen for constructing groynes and breakwaters are preferably angular, this can create a dangerous environment between the rocks; sharp surfaces are usually prevalent. Warning signs are generally installed to mitigate the hazard.

However, rock groynes can be constructed with low crests allowing the majority of the structure to be buried beneath the beach material. Provided that beach levels are maintained and regular beach recharges carried out, the bulk of the rock groynes should remain buried. A capping surface, i.e. a concrete walkway, can be provided along the visible crest if safety is still an issue, but this may increase the cost of construction.

Timber groynes are usually preferable in terms of public safety, although no figures relating to public injury are available to substantiate this. In certain circumstances, a build-up of beach material can leave a large drop on the leeward side of the groyne. This could have safety implications, as the beach on the exposed side would often be submerged. Structures for obtaining access along the beach (over the groynes) might have to be considered, although the use of the seawall and promenade may be deemed sufficient access. The temptation for the public to climb over the groynes of all types will remain a hazard.

Geotextile Bag Breakwaters would be located remotely from the beach and so would avoid creating a hazard close inshore. They would be likely to be used by surfers which could represent an increase in participation in a relatively dangerous activity.

Definitive research on the safety of different types of structure is, however, not currently available. It is understood that HR Wallingford is currently carrying out research into construction safety for the Department of Trade and Industry, and that it is hoped to extend this work into the area of public safety. There is no Defra or Environment Agency national policy on the use of different materals.

Limited research was undertaken by the National Rivers Authority (now Environment Agency) in 1996 on the basis of 31 incidents. The summary results (provided by HR Wallingford) are presented below. The results confirm that slips/trips are the most common form of hazard, but do not provide a conclusive indication that one form of construction is more dangerous. The small number of incidents available for this work means that these results are not definitive.

Views expressed on this matter are often based on perception since comprehensive studies of actual physical harm due to tripping/trapping are not available.

Summary of Accident Data from Environment Agency research project in 1996 based on 31 incidents (provided by HR Wallingford)

(i) Public Safety – Rip Currents A recent report by RNLI (Poole and Bournemouth Water Related Incidents Report – September 2003) has identified that: • the majority (88%) of water-based incidents were associated with groynes • the majority (72%) occurred whilst swimming

• the majority (66%) were due to rip currents (fast flowing, localised, seaward-going current normal to the shoreline associated with wave- induced longshore transport) • the majority (67%) occurred under wave action from the south-east • the majority (78%) involved children or teenagers under the age of 17

This report indicates that addressing the problem of young swimmers being caught in rip-currents would provide the greatest improvement in water-borne public safety. This would not, however, be achieved through removing groynes from the beach, since rip-currents are a naturally occurring coastal process. These are driven by the wave climate and occur on open beaches and on beaches with other forms of control structure such as offshore breakwaters. The removal of groynes would result in the location of rip currents being more variable and, therefore, less predictable, but would not stop them from forming. Since rip-currents have been identified as a problem, other solutions, such as public information and warning signs are recommended.

Hazards of rip-currents to swimmers will not be eliminated through the choice of beach management.

(j) Conclusion On balance, the assessment of environmental sustainability would encourage the selection of a timber groyne scheme. By contrast, the rock groyne option would be preferable on the grounds of buildability, local economic benefit, maintenance, and materials sources. A comparison of the aesthetics, amenity and public safety is more subjective and we do not believe provides a clear preference.

3.1.7 Economic Appraisal The benefits of providing coast protection have been calculated by assessing the damages to residential properties, commercial properties, utility services and amenity that would occur if the seawall was permitted to collapse.

The cash value of the assets at risk if the Do Nothing option were to be adopted would be £316million. When reduced to Present Value and taking into account the existing standard of protection provided by the beach and seawall, the damages would be £156million.

Information on the value of assets and properties was collated in an Geographical Information System. The total number of assets at risk is given in Table 3.1.

Asset Number Residential Properties 672 Utilities – Pumping Stations 12 Commercial Properties 99 Table 3.1 Numbers of Assets at Risk

A summary of the benefits and costs of the Strategy Options is provided in Table 3.2. The estimated costs of each option are stated in the table and the Optimism Bias (which is a contingency percentage required by Defra for the purpose of Grant Aid) has been calculated. The cost streams for each option are provided in the tables at the end of the report. Further details of the calculations are provided in Technical Annex 8.

A comparison of the costs of the options is provided together with the cost streams data. The volumes of recharge used in each of the option are as defined in the Technical Annex 2 – Beach Modelling, with the exception of:

• Given the uncertainty of the management of an open beach, an allowance of error of ± 50% has been applied to the modelling results. • Given the uncertainty in the performance of offshore reefs, which could improve as a result of more detailed modelling, the costs of the Rock Breakwater and Geotextile Reef options have been re-calculated on the basis that these could potentially be made to reduce losses to the same as the 150m Rock Groyne options. A reduction of losses below this level would not be strategically advantageous since this would be expected to increase downdrift erosion within PBY2, PBY3 and Christchurch Bay. An increase in erosion at Hengistbury Head could have the results of exacerbating erosion along much of the Poole and Christchurch Bays frontages as explained further in Section 2.3.

3.1.8 Preferred Strategy The 150m Rock Groyne and Beach Recharge option provides the highest benefit cost ratio of up to bcr=4.2 and the cost uncertainty is low when compared to the alternative options.

Included within the range of scenarios tested for each option is the potential for recharge material to be available from the Swash Channel. Whilst the cost of material from the Swash Channel and Middle Ship Channel is less than from a commercial source, the degree of beach erosion increases when a beach is recharged more frequently. Since both scenarios provide a very similar economic performance, either of them could be adopted. This will allow greater flexibility in the selection source and timing of the recharges.

The following strategy provides the highest benefit coast ratio, being bcr=4.2 and Defra Prioritisation Score of 9.2.

It is recommended that the SMP policy should remain as Hold the Line through Beach Recharge

The recommended way of achieving the SMP policy is by: (a) the dredging of sand of a similar grading to the existing beach from either the Swash Channel entrance (b) pumping ashore of the sand from the dredger through a pipeline (either floating or sunken, depending on the contractor’s preferred plant and methods) (c) transportation of the sand along the beach either through the pipeline or by dumper truck (d) active monitoring and recycling of sediment levels on the beach (e) initial placement of 530,000m3 of sand by bulldozer to a similar slope gradient as the existing beach (f) subsequent recharges of approximately 200,000m3 anticipated to be required every 2 years, decreasing to approximately 70,000m3 and 80,000m3 every 2 years after year 10 and 20, respectively. (g) allowing deterioration of the existing timber groynes (h) in Year 2004: • removal of 20No timber groynes between Sandbanks and Branksome Dene and 5No at Solent Beach • construction of 7No 150m long (450m spacing) rock groynes between Sandbanks to Branksome Dene and 2No at Solent Beach (i) in Year 2014: • removal of 3No timber groynes between Sandbanks and Branksome Dene and 26No at Solent Beach • construction of 1No 150m long (450m spacing) rock groynes

between Branksome Dene and Solent Beach and 8No at Solent Beach (j) in Year 2024: • removal of 18No timber groynes between Sandbanks and Solent Beach • construction of 8No 150m long (450m spacing) rock groynes between Branksome Dene and Solent Beach (k) retaining the existing rock groynes at Sandbanks

Flexibility in the Strategy Since the strategy includes replacement of the existing groynes in 3 phases, the strategy provides some degree of flexibility in the control structures that are used along the Bournemouth – Southbourne frontage. At present, it is considered that the most cost effective method of beach control will be with rock groynes. However, if, in the period up to 2014 when the second phase of rock groynes would be constructed, new evidence is available relating to the other types of structure then this part of the strategy could be updated. It is to be expected that there would be at least one Shoreline Management Plan and one Strategy Study completed for the Poole Bay & Harbour frontage during the intervening period.

3.1.9 Development of Preferred Strategy – Risks and Opportunities The following matters will need to be considered in the development of the scheme to implement the preferred option

(a) Benefit Cost Ratio & Prioritisation Score The Benefit Cost Ratio of the preferred option exceeds 4.0, indicating that the development of a scheme is recommended. However, the Defra Prioritisation Score that is has been calculated for the preferred option is 9.2, which is lower than the threshold required for approval of a scheme, which is currently between 10 – 22 depending on the timing of the approval and the works. This indicates that in the development of the scheme, including the Project Appraisal Report which justifies the application for Grant Aid, will need to focus on controlling and, if possible, reducing costs. At scheme stage, a further review of the benefits of the scheme may provide even greater economic justification particularly in: • the valuation of commercial properties, which has been calculated on a generic, rather than individual, basis

• the rate of increase of value of sea front property since Council Tax valuations in 1991 • the value of promenade assets, • early accelerated erosion higher than 1.0m/year once the sea wall has collapsed • the potential for adoption of standards of protection higher than 1:100 years which may provide considerably greater benefits with a small increase in cost

(b) Design of Rock Groynes The selection of control structures for the PBY1 frontage is recognised as contentious issue. The acceptance of the used of rock groynes will depend to certain degree on the final design. The groynes at Sandbanks have horizontal crest levels; these structures are efficient in trapping sediment and reducing the risk of erosion by forcing tidal flows away from the beach front. The trapping of sediment under wave action (rather than tidal flows) can be achieved with groynes of lower crest levels which slope seaward. A low-profile design, together with a wider groyne spacing would reduce the visual impact of the structures. The provision of pedestrian access over the groynes would also be an essential consideration.

(c) Availability of Recharge The preferred strategy depends on the availability of suitable sand beach recharge. At present it has been assumed that material will be available from the proposed one-off capital dredging and from ongoing maintenance dredging of the Swash Channel and Middle Ship Channel of Poole Harbour in the quantities stated. If such material is not available then other sand could be obtained on a 10 yearly basis from the commercial sources described at a marginal cost increase.

(d) Placement of Recharge The initial beach recharge is required to widen the beach along the whole frontage. After this work, the location of subsequent 2- yearly recharges would depend on 2 factors:

(i) The placement location should be based on the present understanding (Technical Annex 5) of longshore transport. There is a drift divide in the region of Poole Head – Branksome Dene (the location will move depending on the prevailing wave

and tidal conditions) with net longshore transport from Poole Head to Sandbanks being controlled by flood tide currents into Poole Harbour and net longshore transport from Branksome Dene to Point Café (and beyond) being controlled by wave action. It is to be expected that the beach recharge placed between Poole Head – Branksome Dene will feed the adjacent frontages and would provide the more benefit overall than beach recharge placed (for example) at the ends of the PBY1 frontage

(ii) The need to maintain the beach width based at all points along the frontage. The results of the previous year’s beach monitoring should be used to determine which locations have been subject to the most erosion.

It is not possible therefore to decide now where each recharge should be placed as this would be determined from feedback based on the beach performance over the pervious years.

DESCRIPTION No Active Hold the Hold the Hold the Hold the Hold the Hold the Hold the Hold the Hold the Intervention Line A Line B Line C Line D Line E Line F Line G Line H Line I PBY0.1 Maintain/enhance recreational N Y Y Y Y Y Y Y Y Y resources in the coastal zone, where environmental sustainable, practical, economic and financially viable. PBY1.1 Avoid constructing any new Y Y Y Y Y Y Y Y Y Y coastal defences that would be detrimental to the earth science or nature conservation value of Poole Bay Cliffs SSSI PBY1.2 Avoid constructing any new Y Y Y Y Y Y Y Y Y Y coastal defences that would be detrimental to the earth science or nature conservation value of Sandbanks SNCI, Flaghead Chine SNCI, Branksome Chine SNCI, Bournemouth Cliffs SNCI or Southbourne Cliffs SNCI PBY1.3 Protect properties of N Y Y Y Y Y Y Y Y Y architectural merit within Bournemouth Conservation Areas and other residential and commercial property along the frontage where technically feasible, environmentally sustainable and economically viable

Table 2.1.1 - Sandbanks Ferry Slipway to Point House Café Strategy Options

Notes: 1) Options have been assessed against the objectives with the following outcomes: Y = this option meets the objective N = this option does not meet the objective ? = uncertain whether this option meets the objective or not 2) Objectives in bold italics arise from legal obligations, including the Habitats Regulations and Water Resources Act 3) Other objectives do not represent legal obligations 4) Objectives that are underlined identify where there is potential conflict with another objectives

3.2 Point House Café to Warren Hill – PBY 2

3.2.1 Existing Shoreline & Defences The shoreline comprises: an open grassed amenity area, with car parks, low dunes along the seaward edge and a sand and shingle beach. At the east end of the management unit there are earth bunds which forms Double Dykes, part of the Hengistbury Head Scheduled Monument.

The beach is controlled by 7 groynes, 2 of which are timber and gabion basket construction, 2 are simple timber construction and the other 3 are rock. The rock groynes are not expected to require renewal or substantial maintenance within the 50 year Strategy Period.

The replacement of the 4 timber groynes with 3 rock groynes have been included within the PBY1 frontage to allow for the transition between the two management units.

The historic rate of erosion of the cliffs in this management unit over the period 1978 to 2001 was established in the course of this study through comparison of geo-rectified aerial photographs (see Technical Annex 3). The extent of shoreline change over the period 1974 to 2001 is shown in Figure 3.13. This includes intervention works following erosion events at White Pits, where the low cliff was filled and at Double Dykes, where a gabion wall was constructed.

Details of environmental issues, designations and objectives are provided in Technical Annex 10.

3.2.2 Flood and Coast Defence Problem The erosion of the shoreline could have a number of effects:

• A full breach of the peninsular at a point between Point House Café and Hengistbury Head could open a new entrance to Christchurch Harbour • The Scheduled Monument of Double Dykes and other features of archaeological value could be eroded

(a) Full Breach of the Peninsular The likelihood of breaching of the land between Pont House Café and Hengistbury Head can be judged from the comparison of: (i) computer modelling of beach draw-down under storm events (Technical Annex 2) and (ii) topographic cross sections of the peninsular produced in GIS using LiDAR surveys and Admiralty Chart surveys

The extent of beach erosion under storm conditions was simulated at Double Dykes using computer modelling of waves and cross-shore sediment transport (Technical Annex 3). Under the 1:100 year condition, which has 1% probability of occurrence in any year, the beach was eroded by 11m (Table 3.1)

Location 1:1 year 1:10 year 1:100 year condition condition condition Double Dykes (B5) 5m 8m 11m Table 3.1 Extent of beach erosion under storm conditions using COSMOS (extracted from Technical Annex 3)

For comparison, the cross-section of the land immediately to the east of Double Dykes (which is the narrowest and lowest point of the Hengistbury Head peninsular) is some 250m wide. Figure 3.14 shows an oblique image of the Headland with 4 cross-sections (A-A, B-B, C-C and D-D) which were analysed and compared. Of these cross-sections, Section C-C was found the be the lowest and narrowest part of the headland and is reproduced in Figure 3.15. Whilst it is not possible to evaluate the likelihood of a full breach of this land, it is expected from this comparison to be considerably less likely than 1% in any year. Since the highest indicative standard of protection under Defra guidance is 1:100-1:300 year

return period (which is equivalent to 0.3% - 1.0% probability of occurrence in any year), it is not expected that protection works against a more severe (“catastrophic”) event in excess of this standard would be justified.

Future erosion of the cliff line will reduce the width of the peninsular, but on the basis of the historical rates of up to 0.15m/year over the past 24 years, it is unlikely that this assessment would substantially change by 2054.

(b) Erosion of archaeological sites The rate of erosion locally at Double Dykes has been reduced by the construction of a gabion wall over a length of some 150m. This structure is not expected to last for the duration of the Strategy Period due to the deterioration of the wire baskets through corrosion. From comparison of geo-rectified aerial photographs from 1974 and 2001, the cliffline immediately to the east of this structure over a length of some 100-200m appears to have eroded marginally more than elsewhere (Figure 3.13). Protection of this monument may, therefore, have caused localised increase in erosion, but the consequences are considered to be insignificant. If the gabion wall is allowed to deteriorate and to fail, it is expected that the reclaimed land to the seaward side of Double Dykes would erode rapidly within 1-3 years. Subsequent erosion of the monument would be expected to be similar to existing erosion rates of up to 0.15m/year. Assuming a residual life of the gabion wall of some 10 years, approximately 5-10m of Double Dykes could be eroded in the course of the Strategy Period.

3.2.3 Current SMP Policy (adopted 1999) The current policy is Selectively Hold the Existing Line (maintenance of existing structures & implementation of new schemes at eastern end) in the Short Term and Selectively Hold the Existing Line (to coincide with the next phase of beach nourishment in PBY1) in the Long Term.

Following the change in the Defra guidance regarding the description of SMP policies, the policy “Selectively Hold the Line” is considered to be more accurately described as “Limited Intervention”.

3.2.4 Strategic Options The following options have been developed as ways of achieving the SMP Policy

Strategic Option Description No Active No action taken apart from fulfilling H&S requirements Intervention Limited This option would include: Intervention • replacement of the 4 timber groynes at the west end of the frontage and construction of 3 rock groynes (which is included as part of the PBY 1 strategy to allow a transition between the two management units) • allowing on-going feed of sediment from beach recharge in PBY1 and allowing maintenance of the Long Groyne in PBY3 • minimum maintenance of the rock groynes • remove the gabion baskets from Double Dykes as they fail, to reduce the safety risk to the public • regularly monitoring the cliff line change

Limited This option would include: Intervention • replacement of the 4 timber groynes at the west end of the frontage and (including Hold construction of 3 rock groynes (which is included as part of the PBY 1 strategy to the Line locally at allow a transition between the two management units) Double Dykes) • allowing on-going feed of sediment from beach recharge in PBY1 and allowing maintenance of the Long Groyne in PBY3 • minimum maintenance of the rock groynes • remove the gabion baskets from Double Dykes and replace with a more robust structure, such as a rock revetment • regularly monitoring the cliff line change

Table 3.12

The No Active Intervention option would not allow for removal of the existing timber groynes and construction of rock groynes, which is integral to the preferred option for the PBY1 frontage. Whilst these structures would be located within PBY2, their purpose would be to allow a transition between the active management of PBY1 and the Limited Intervention of PBY2. The option of No Active Intervention is therefore not recommended since it is inconsistent with the Hold the Line policy for PBY1.

To avoid increased erosion of the cliffline and to avoid incurring considerable demolition costs, it is reasonable to leave the existing 3 rock groynes in place and to provide minimum maintenance, such as replacement of rocks due to storm damage. This degree of intervention should only be required perhaps once per

decade and could be included in the construction works for the PBY1 frontage at marginal additional cost.

3.2.5 Strategic Environmental Assessment The specific objectives for this area have been established as part of the Strategic Environmental Assessment (see Technical Annexe 10, Table 5.2). These have been summarised in Table 2.2.1.

Limited Intervention (including Hold the Line locally at Double Dykes) is the preferred environmental option and would meet all the objectives. In particular, it would allow for protection of the Double Dykes, which is part of the Hengistbury Head Scheduled Monument. English Nature has indicated that it has less concern over the condition of the cliffs with regard to exposure of the geology in this area compared to the higher cliffs in PBY3.

3.2.6 Economic Appraisal There are no residential or commercial assets at risk up to the indicative standard of 1:100 – 1:300 years. It is recognised that there could be intangible benefits arising from protecting Double Dykes. However, current guidance on Economic Appraisal does not indicate that such benefits would be sufficient to justify Defra Grant Aid. As a result, the Limited Intervention (including Hold the Line locally at Double Dykes) option cannot be pursued unless funding from other sources can be identified.

3.2.7 Preferred Strategy

It is recommended that the SMP policy should be amended to Limited Intervention

The recommended way of achieving the SMP policy is by: • replacement of the 4 timber groynes at the west end of the frontage and construction of 3 rock groynes (which is included as part of the PBY 1 strategy to allow a transition between the two management units) • minimum maintenance of the existing 3 rock groynes • remove the gabion baskets from Double Dykes as they fail, to reduce the safety risk to the public

The frontage will benefit from:

• on-going feed of sediment from beach recharge in PBY1 • on-going maintenance of the Hengistbuty Head Long Groyne in PBY3

3.2.8 Development of Preferred Strategy – Risks and Opportunities

(a) Double Dykes Whilst the current strategy does not include the maintenance or improvement of the protection to Double Dykes, it does demonstrate that: • such protection would not cause a significant detrimental erosion downdrift of this point • English Nature would have less concern over the condition of the cliffs with regard to exposure of the geology in this area compared to the higher cliffs in PBY3.

In addition, the continuing presence of the rock groynes immediately to seaward of the monument and the on-going feed of beach recharge into this management unit should prolong the life of the existing gabions basket structure.

If sources of funding other than Defra Grant Aid can be obtained, it is recommended that a more robust structure be constructed to provide localise protection to Double Dykes. The provision of a rock revetment of 150m length would be expected to cost in the region of £150,000 - £300,000 depending on the design. Other forms of structure might allow lower construction costs, for example, the use of gabion baskets, but are unlikely to provide the same life span.

(b) Education Centre It is understood that an Education Centre is planned to be constructed by Bournemouth Borough Council at the Double Dykes Car Park. The benefit of protecting this building cannot be included within the present strategy, since it is not an existing asset.

It is recommended that the potential effects of erosion and flooding on the building be considered in the course of the design.

(c) Monitoring of cliffline and beach erosion Confidence in the results of historical erosion is reasonable as the images have been geo-rectified, the errors evaluated and the study covers an epoch of 24 years. However the following factors mean that the future rates may be different from the results found in this study:

(i) the recommended strategy is based on only 2 sets of aerial photographs. (ii) climate change factors, as described in Technical Annex 7, may mean that future cliff line erosion will not be the same as historic rates (iii) measurement of the cliffline does not indicate whether beach narrowing may lead to accelerated erosion in the future

The extent of erosion of the cliffline and the beach can be readily monitored in future through the Defra sponsored South Coast Regional Monitoring study which is expected to include the aerial photography and ortho-rectification on an annual basis. These photographs can be used for a regular comparison of the position of the cliffline using the same method as the present study (Technical Annex 3). This monitoring work can be reviewed as part of future Shoreline Management Plans and Strategy Studies, such that the strategy can be revised, if substantial changes in erosion rates are identified.

It is recommended that comparison of ortho-rectified photographs be carried out every five years to monitor the on-going erosion of this PBY2 management unit.

DESCRIPTION No Active Intervention Limited Intervention Limited Intervention (including Hold the Line at Double Dykes) PBY0.1 Maintain/enhance recreational N Y Y resources in the coastal zone, where environmental sustainable, practical, economic and financially viable. PBY2.1 Subject to natural coastal N Y Y processes, to maintain in favourable condition the habitat of, or where in unfavourable condition, to restore to favourable condition the habitat of Christchurch Harbour SSSI and Hengistbury Head from loss to erosion, or (to the extent that this is not possible), re-create such habitats on adjacent land: • Unimproved acid grassland • Grass/sedge/heath mosaic • Lagoonal habitat PBY2.2 Avoid constructing any new Y Y Y coastal defences that would be (English Nature has confirmed that detrimental to the earth science or localised protection to Double nature conservation value of Dykes would not be considered to Southbourne Cliffs SNCI be detrimental)

PBY2.3 Protect Hengistbury Head N N Y Scheduled Monument from loss to erosion or flooding, to the extent that this is technically possible and environmentally sustainable

Table 2.2.1 - Point House Café to Warren Hill Strategy Options

3.3 Warren Hill to Hengistbury Long Groyne – PBY 3

3.3.1 Existing Shoreline & Defences The shoreline comprises a mixed beach of sand and shingle, with cliffs of sands and muds behind. Hengistbury Head Long Groyne, which is constructed in concrete with rock reinforcement, is located at the eastern end of the frontage.

3.3.2 Flood and Coast Defence Problem As noted in Section 2 the Hengistbury Head Long Groyne has had direct effect on the cliffs for a distance of 500m to the west of the structure. The historic aerial photographs show that alignment of the cliffs within this part of the PBY3 frontage has effectively been held for at least the past 24 years. Wave attack has not been able to reach the base of the cliffs due to the increasing width of the beach and the building of the dunes. The only cliff erosion has been due to wind/rain weathering.

The lack of erosion has the indirect effect of helping to maintain the shoreline position in both Poole Bay and Christchurch Bays possibly as far as west as Branksome Dene to the west and as far east as Milford on Sea (see Section 2.4). It follows that the maintenance of the structure is an essential part of the Hold the

Line Policy in PBY1. Implicit in this is also the recognition that the policy for the shoreline over the 500m immediately to the west of the Long Groyne should also be to Hold the Line. This has been achieved over the past 24 years without any intervention other than maintenance of the Long Groyne and ongoing beach recharge in PBY1.

Over the remaining 500m of this frontage, the rate of erosion of the cliff was found to be on average 0.15m/year over the past 24 years. This rate is averaged both along the frontage and over time, with the result that at specific locations along the cliff the observed rate could be more than an order of magnitude (ten times) greater in a single year. However, when considering long-term erosion, the averaged rate is the most appropriate to consider.

This rate of erosion is lower than might normally be expected of soft cliffs that are at an exposed location. This is due to the feed of sediment from the west into this frontage which sustains the beach levels and reduces the degree of wave attack at the cliff base. If this feed were to stop, the rate of erosion would be expected to increase considerably, towards the rate of 1m/year which has been identified at locations of downdrift erosion elsewhere in the PBY frontage (Technical Annex 8).

Figure 3.16 Location of Greatest Erosion between 1978 and 2002

Over the 50 year strategy period, based on the assumption that this rate is sustained, the extent of cliff erosion at the west end of the PY3 frontage would be

7.5m on average. Given that the greatest erosion that occurred at any point on the cliff between 1978 and 2002 was approximately 10m (this occurred at two locations as shown in Figure 3.16), the degree of erosion at particular locations could be up to 20m during the Strategy Period. As described in Technical Annex 7, it is difficult to allow for all of the factors that will results from Climate Change, but an arbitrary allowance of 50% increase in erosion would only result in an average erosion of the order of 10m and the greatest erosion at any point of some 30m.

This degree of erosion will not put any properties at risk. There would however be some impact on Geological, Archaeological and Ecological interests of the site. This is discussed further in the Strategic Environmental Assessment.

3.3.3 Current SMP Policy (adopted 1999) The Short and Long Term policies are to Retreat the Line of the Landform, whilst Selectively Holding the Beach Width (with rock groynes to the west of the unit).

As a result of the work carried out in this strategy, it is now identified that the shoreline for 500m to the west of the Long Groyne has been held in place for the past 24 years and that this Hold the Line practice is critical to the Hold the Line policy for PBY1 (and for locations within Christchurch Bay not covered by this Strategy, but included within the Christchurch Bay Strategy Study). Consequently, it is recommended that the Management Unit be divided into 2 parts:

• PBY3a Warren Hill • PBY3b Hengistbury Head

Following the change in the Defra guidance regarding the description of SMP policies, the policy of “Retreat the Line” for PBY3a is considered to be more accurately described as “Limited Intervention”. The target intervention, as agreed through consensus (Section 2.4) is to maintain the current rate of erosion.

It is recommended that the SMP Policy for PBY3b be amended to Hold the Line, in view of the de facto strategy of the past 24 years and the importance of the headland to the Hold the Line Policy in PBY1.

3.3.4 Strategic Options

The following options have been developed as ways of achieving the SMP Policy

Strategic Option Description No Active Intervention No action taken apart from fulfilling H&S requirements PBY3a – No action taken apart from: Limited Intervention • fulfilling H&S requirements PBY3b – • holding the position of the headland by Hold the Line maintaining the Long Groyne • regularly monitoring the cliff line change

On the basis of historical erosion rates, the use of beach control structures, such as groynes, breakwaters or reefs would not appear to be required to achieve the objective of maintaining the existing rate of erosion.

3.3.5 Strategic Environmental Assessment The specific objectives for this area have been established as part of the Strategic Environmental Assessment (see Technical Annex 10, Table 5.2). These have been summarised in Table 3.3.1, together with the implications of adopting the No Active and Limited Intervention options.

Limited Intervention is the preferred environmental option and would meet all the objectives of preventing erosion or flooding damage, maintaining recreational resources through beach recharge and maintaining the Long Groyne, as well as maintaining dynamic coastal processes. Provided it is implemented through maintaining existing defences and beach recharge, then possible conflicts with the conservation and landscape value are likely to be avoided. This option is considered to be in-line with the views expressed by the various stakeholders during the consultation meeting described in Section 2.5.

3.3.6 Economic Appraisal There are no residential or commercial assets at risk up to the indicative standard of 1:100 – 1:300 years. Current guidance on Economic Appraisal does not indicate that such benefits would be sufficient to justify Defra Grant Aid. As a result, the Limited Intervention (including Hold the Line locally at Double Dykes) option cannot be pursued unless funding from other sources can be identified.

No economic appraisal was required. Since the maintenance of Long Groyne is beneficial to the Bournemouth-Southbourne frontage, the costs of maintenance have been included within the economic appraisal of PBY1.

3.3.7 Preferred Strategy

It is recommended that the SMP policy be amended to: • PBY3a - Limited Intervention • PBY3b - Hold the Line (only through maintenance of the Long Groyne and ongoing beach recharge in PBY1)

The recommended way of achieving the SMP policy is therefore by: • fulfilling H&S requirements • holding the position of the headland by maintaining the Long Groyne • monitoring the cliff line change every 5 years using ortho-rectified aerial photographs

3.3.8 Development of Preferred Strategy – Risks and Opportunities

(a) Monitoring of cliffline and beach erosion Confidence in the results of historical erosion is reasonable as the images have been geo-rectified, the errors evaluated and the study covers an epoch of 24 years. However the following factors mean that the future rates may be different from the results found in this study:

The extent of erosion of the cliffline and the beach can be readily monitoring in future through the Defra sponsored South Coast Regional Monitoring study which is expected to include the aerial photography and ortho-rectification on an annual basis. These photographs can be used for a regular comparison of the position of the cliffline using the same method as the present study (Technical Annex 3). This

monitoring work can be reviewed as part of future Shoreline Management Plans and Strategy Studies, such that the strategy can be revised, if substantial changes in erosion rates are identified.

It is recommended that comparison of ortho-rectified photographs be carried out every five years to monitor the on-going erosion of this PBY3 management unit.

DESCRIPTION PBY 3a – PBY 3a – No Active Limited Intervention A Limited Intervention B Intervention PBY 3b – PBY 3b – Hold the Line Hold the Line PBY0.1 Maintain/enhance recreational resources in the coastal zone, where N Y Y environmentally sustainable, practical, economic and financially viable. PBY3.1 Subject to natural coastal processes, to maintain in favourable condition the habitat of, or where in unfavourable condition, to restore to favourable condition the habitat of Dorset Heaths and Studland Dunes cSAC and Christchurch Harbour SSSI on Hengistbury Head from loss to erosion or flooding, or (to the extent that this is not N Y N possible), re-create such habitats on adjacent land: • Heathland • Unimproved acid grassland • Grass/sedge/heath mosaic • Lagoonal habitats PBY3.2 Protect Hengistbury Head Scheduled Monument from loss to erosion or flooding, to the extent that this is technically possible and environmentally N Y Y sustainable PBY3.3 Protect Hengistbury Head as a recreational resource from erosion, to N Y Y the extent that this is technically possible and environmentally sustainable PBY3.4 Maintain/manage dynamic coastal processes to maintain geological Y Y N exposures at Hengistbury Head Cliffs for access and study

Table 3.3.1 - Warren Hill to Hengistbury Long Groyne Strategy Options

4 References

Halcrow (1999), Poole and Christchurch Bays Shoreline Management Plan

HR Wallingford (2003), Poole Bay & Harbour Strategy Study, Computational Modelling Studies, EX4555

Silvester & Hsu (1993), Coastal Stabilisation: Innovative Concepts, Prentice Hall, Engelwood Cliffs, New Jersey

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A3 (Open Beach Recharge - assuming Capital A4 (Open Beach Recharge - assuming no Capital A1 (Open Beach Recharge - assuming Capital A2 (Open Beach Recharge - assuming no Capital Swash Channel Dredging) (minus 50% in Swash Channel Dredging) (plus 50% in recharge Swash Channel Dredging) TOTALS:Swash Channel Dredging) TOTALS: recharge volumes) TOTALS:volumes) TOTALS:

Control Beach Professional Control Beach Professional Control Beach Professional Control Beach Professional Cash PV Cash PV Cash PV Cash PV Structures Recharge Services Structures Recharge Services Structures Recharge Services Structures Recharge Services

cash sum 3,168,000 126,951,804 3,555,000 133,674,804 61,906,903 3,168,000 129,479,974 3,555,000 136,202,974 64,435,073 3,168,000 66,556,102 3,555,000 73,279,102 36,230,899 3,168,000 192,403,846 3,555,000 199,126,846 92,639,246 Discount year Factor 0 1.000 1,100,000 1,104,060 315,000 2,519,060 2,519,060 1,100,000 3,632,230 315,000 5,047,230 5,047,230 1,100,000 3,632,230 315,000 5,047,230 5,047,230 1,100,000 3,632,230 315,000 5,047,230 5,047,230 1 0.966 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0.934 0 3,632,230 135,000 3,767,230 3,516,750 0 3,632,230 135,000 3,767,230 3,516,750 0 1,816,115 135,000 1,951,115 1,821,387 0 5,448,345 135,000 5,583,345 5,212,112 3 0.902 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4 0.871 0 3,632,230 135,000 3,767,230 3,282,923 0 3,632,230 135,000 3,767,230 3,282,923 0 1,816,115 135,000 1,951,115 1,700,284 0 5,448,345 135,000 5,583,345 4,865,563 5 0.842 704,000 0 704,000 592,749 704,000 0 704,000 592,749 704,000 0 0 704,000 592,749 704,000 0 0 704,000 592,749 6 0.814 0 4,439,530 135,000 4,574,530 3,721,383 0 4,439,530 135,000 4,574,530 3,721,383 0 2,219,765 135,000 2,354,765 1,915,603 0 6,659,295 135,000 6,794,295 5,527,163 7 0.786 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 8 0.759 0 4,439,530 135,000 4,574,530 3,473,951 0 4,439,530 135,000 4,574,530 3,473,951 0 2,219,765 135,000 2,354,765 1,788,236 0 6,659,295 135,000 6,794,295 5,159,666 9 0.734 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 10 0.709 660,000 4,706,468 135,000 5,501,468 3,900,094 660,000 4,706,468 135,000 5,501,468 3,900,094 660,000 2,353,234 135,000 3,148,234 2,231,842 660,000 7,059,702 135,000 7,854,702 5,568,346 11 0.685 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 12 0.662 0 4,706,468 135,000 4,841,468 3,204,003 0 4,706,468 135,000 4,841,468 3,204,003 0 2,353,234 135,000 2,488,234 1,646,672 0 7,059,702 135,000 7,194,702 4,761,334 13 0.639 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 14 0.618 0 4,706,468 135,000 4,841,468 2,990,971 0 4,706,468 135,000 4,841,468 2,990,971 0 2,353,234 135,000 2,488,234 1,537,186 0 7,059,702 135,000 7,194,702 4,444,756 15 0.597 352,000 0 352,000 210,105 352,000 0 352,000 210,105 352,000 0 0 352,000 210,105 352,000 0 0 352,000 210,105 16 0.577 0 5,372,410 135,000 5,507,410 3,176,156 0 5,372,410 135,000 5,507,410 3,176,156 0 2,686,205 135,000 2,821,205 1,627,006 0 8,058,615 135,000 8,193,615 4,725,306 17 0.557 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 18 0.538 0 5,372,410 135,000 5,507,410 2,964,976 0 5,372,410 135,000 5,507,410 2,964,976 0 2,686,205 135,000 2,821,205 1,518,827 0 8,058,615 135,000 8,193,615 4,411,124 19 0.520 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 20 0.503 352,000 5,656,000 135,000 6,143,000 3,087,262 352,000 5,656,000 135,000 6,143,000 3,087,262 352,000 2,828,000 135,000 3,315,000 1,666,006 352,000 8,484,000 135,000 8,971,000 4,508,519 21 0.486 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 22 0.469 0 5,656,000 135,000 5,791,000 2,716,851 0 5,656,000 135,000 5,791,000 2,716,851 0 2,828,000 135,000 2,963,000 1,390,093 0 8,484,000 135,000 8,619,000 4,043,609 23 0.453 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 24 0.438 0 5,656,000 135,000 5,791,000 2,536,210 0 5,656,000 135,000 5,791,000 2,536,210 0 2,828,000 135,000 2,963,000 1,297,667 0 8,484,000 135,000 8,619,000 3,774,753 25 0.423 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 26 0.409 0 5,656,000 135,000 5,791,000 2,367,579 0 5,656,000 135,000 5,791,000 2,367,579 0 2,828,000 135,000 2,963,000 1,211,386 0 8,484,000 135,000 8,619,000 3,523,772 27 0.395 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 28 0.382 0 5,656,000 135,000 5,791,000 2,210,160 0 5,656,000 135,000 5,791,000 2,210,160 0 2,828,000 135,000 2,963,000 1,130,842 0 8,484,000 135,000 8,619,000 3,289,479 29 0.369 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 30 0.356 0 5,656,000 135,000 5,791,000 2,063,208 0 5,656,000 135,000 5,791,000 2,063,208 0 2,828,000 135,000 2,963,000 1,055,653 0 8,484,000 135,000 8,619,000 3,070,764 31 0.344 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 32 0.333 0 5,656,000 135,000 5,791,000 1,926,027 0 5,656,000 135,000 5,791,000 1,926,027 0 2,828,000 135,000 2,963,000 985,463 0 8,484,000 135,000 8,619,000 2,866,591 33 0.321 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 34 0.310 0 5,656,000 135,000 5,791,000 1,797,967 0 5,656,000 135,000 5,791,000 1,797,967 0 2,828,000 135,000 2,963,000 919,941 0 8,484,000 135,000 8,619,000 2,675,993 35 0.300 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 36 0.290 0 5,656,000 135,000 5,791,000 1,678,421 0 5,656,000 135,000 5,791,000 1,678,421 0 2,828,000 135,000 2,963,000 858,774 0 8,484,000 135,000 8,619,000 2,498,068 37 0.280 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 38 0.271 0 5,656,000 135,000 5,791,000 1,566,824 0 5,656,000 135,000 5,791,000 1,566,824 0 2,828,000 135,000 2,963,000 801,675 0 8,484,000 135,000 8,619,000 2,331,973 39 0.261 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 40 0.253 0 5,656,000 135,000 5,791,000 1,462,647 0 5,656,000 135,000 5,791,000 1,462,647 0 2,828,000 135,000 2,963,000 748,372 0 8,484,000 135,000 8,619,000 2,176,922 41 0.244 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 42 0.236 0 5,656,000 135,000 5,791,000 1,365,397 0 5,656,000 135,000 5,791,000 1,365,397 0 2,828,000 135,000 2,963,000 698,613 0 8,484,000 135,000 8,619,000 2,032,180 43 0.228 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 44 0.220 0 5,656,000 135,000 5,791,000 1,274,613 0 5,656,000 135,000 5,791,000 1,274,613 0 2,828,000 135,000 2,963,000 652,163 0 8,484,000 135,000 8,619,000 1,897,062 45 0.213 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 46 0.205 0 5,656,000 135,000 5,791,000 1,189,864 0 5,656,000 135,000 5,791,000 1,189,864 0 2,828,000 135,000 2,963,000 608,801 0 8,484,000 135,000 8,619,000 1,770,928 47 0.199 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 48 0.192 0 5,656,000 135,000 5,791,000 1,110,751 0 5,656,000 135,000 5,791,000 1,110,751 0 2,828,000 135,000 2,963,000 568,323 0 8,484,000 135,000 8,619,000 1,653,180 49 0.185 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 PV 2,547,644 57,512,407 1,846,852 PV 2,547,644 60,040,577 1,846,852 PV 2,547,644 31,836,403 1,846,852 PV 2,547,644 88,244,750 1,846,852 PV

A - COSTS Open Beach Client/Authority Bournemouth Borough Council / Borough of Poole Project name Poole Bay and Harbour Strategy Study Project reference WCPBHS Base date for estimates (year 0) Jun-2004 Scaling factor (e.g. £m, £k, £) £ Discount rate 3.5%

B1 (Timber Groynes 2-yearly Beach Recharge - B2 (Timber Groynes 2-yearly Beach Recharge - C1 (Timber Groynes 10-yearly Beach Recharge - C2 (Timber Groynes 10-yearly Beach Recharge - assuming Capital Swash Channel Dredging) TOTALS: assuming no Capital Swash Channel Dredging) TOTALS: assuming Capital Swash Channel Dredging) TOTALS: assuming no Capital Swash Channel Dredging) TOTALS:

cash sum 44,308,000 107,212,500 315,000 151,835,500 76,303,580 44,308,000 113,943,750 315,000 158,566,750 83,034,830 44,308,000 88,537,500 315,000 133,160,500 70,856,245 44,308,000 96,187,500 315,000 140,810,500 78,506,245 Discount year Factor 0 1.000 5,500,000 2,587,500 315,000 8,402,500 8,402,500 5,500,000 9,318,750 315,000 15,133,750 15,133,750 5,500,000 11,587,500 315,000 17,402,500 17,402,500 5,500,000 19,237,500 315,000 25,052,500 25,052,500 1 0.966 792,000 0 792,000 765,217 792,000 0 792,000 765,217 792,000 0 792,000 765,217 792,000 0 792,000 765,217 2 0.934 792,000 4,359,375 5,151,375 4,808,864 792,000 4,359,375 5,151,375 4,808,864 792,000 0 792,000 739,340 792,000 0 792,000 739,340 3 0.902 792,000 0 792,000 714,339 792,000 0 792,000 714,339 792,000 0 792,000 714,339 792,000 0 792,000 714,339 4 0.871 792,000 4,359,375 5,151,375 4,489,126 792,000 4,359,375 5,151,375 4,489,126 792,000 0 792,000 690,182 792,000 0 792,000 690,182 5 0.842 792,000 0 792,000 666,843 792,000 0 792,000 666,843 792,000 0 792,000 666,843 792,000 0 792,000 666,843 6 0.814 792,000 4,359,375 5,151,375 4,190,647 792,000 4,359,375 5,151,375 4,190,647 792,000 0 792,000 644,293 792,000 0 792,000 644,293 7 0.786 792,000 0 792,000 622,505 792,000 0 792,000 622,505 792,000 0 792,000 622,505 792,000 0 792,000 622,505 8 0.759 792,000 4,359,375 5,151,375 3,912,014 792,000 4,359,375 5,151,375 3,912,014 792,000 0 792,000 601,454 792,000 0 792,000 601,454 9 0.734 792,000 0 792,000 581,115 792,000 0 792,000 581,115 792,000 0 792,000 581,115 792,000 0 792,000 581,115 10 0.709 792,000 4,359,375 5,151,375 3,651,907 792,000 4,359,375 5,151,375 3,651,907 792,000 19,237,500 20,029,500 14,199,289 792,000 19,237,500 20,029,500 14,199,289 11 0.685 792,000 0 792,000 542,477 792,000 0 792,000 542,477 792,000 0 792,000 542,477 792,000 0 792,000 542,477 12 0.662 792,000 4,359,375 5,151,375 3,409,094 792,000 4,359,375 5,151,375 3,409,094 792,000 0 792,000 524,132 792,000 0 792,000 524,132 13 0.639 792,000 0 792,000 506,408 792,000 0 792,000 506,408 792,000 0 792,000 506,408 792,000 0 792,000 506,408 14 0.618 792,000 4,359,375 5,151,375 3,182,426 792,000 4,359,375 5,151,375 3,182,426 792,000 0 792,000 489,283 792,000 0 792,000 489,283 15 0.597 792,000 0 792,000 472,737 792,000 0 792,000 472,737 792,000 0 792,000 472,737 792,000 0 792,000 472,737 16 0.577 792,000 4,359,375 5,151,375 2,970,828 792,000 4,359,375 5,151,375 2,970,828 792,000 0 792,000 456,751 792,000 0 792,000 456,751 17 0.557 792,000 0 792,000 441,305 792,000 0 792,000 441,305 792,000 0 792,000 441,305 792,000 0 792,000 441,305 18 0.538 792,000 4,359,375 5,151,375 2,773,300 792,000 4,359,375 5,151,375 2,773,300 792,000 0 792,000 426,382 792,000 0 792,000 426,382 19 0.520 792,000 0 792,000 411,963 792,000 0 792,000 411,963 792,000 0 792,000 411,963 792,000 0 792,000 411,963 20 0.503 792,000 4,359,375 5,151,375 2,588,905 792,000 4,359,375 5,151,375 2,588,905 792,000 19,237,500 20,029,500 10,066,143 792,000 19,237,500 20,029,500 10,066,143 21 0.486 792,000 0 792,000 384,572 792,000 0 792,000 384,572 792,000 0 792,000 384,572 792,000 0 792,000 384,572 22 0.469 792,000 4,359,375 5,151,375 2,416,771 792,000 4,359,375 5,151,375 2,416,771 792,000 0 792,000 371,567 792,000 0 792,000 371,567 23 0.453 792,000 0 792,000 359,002 792,000 0 792,000 359,002 792,000 0 792,000 359,002 792,000 0 792,000 359,002 24 0.438 792,000 4,359,375 5,151,375 2,256,081 792,000 4,359,375 5,151,375 2,256,081 792,000 0 792,000 346,862 792,000 0 792,000 346,862 25 0.423 792,000 0 792,000 335,132 792,000 0 792,000 335,132 792,000 0 792,000 335,132 792,000 0 792,000 335,132 26 0.409 792,000 4,359,375 5,151,375 2,106,076 792,000 4,359,375 5,151,375 2,106,076 792,000 0 792,000 323,799 792,000 0 792,000 323,799 27 0.395 792,000 0 792,000 312,850 792,000 0 792,000 312,850 792,000 0 792,000 312,850 792,000 0 792,000 312,850 28 0.382 792,000 4,359,375 5,151,375 1,966,045 792,000 4,359,375 5,151,375 1,966,045 792,000 0 792,000 302,270 792,000 0 792,000 302,270 29 0.369 792,000 0 792,000 292,049 792,000 0 792,000 292,049 792,000 0 792,000 292,049 792,000 0 792,000 292,049 30 0.356 792,000 4,359,375 5,151,375 1,835,324 792,000 4,359,375 5,151,375 1,835,324 792,000 19,237,500 20,029,500 7,136,078 792,000 19,237,500 20,029,500 7,136,078 31 0.344 792,000 0 792,000 272,630 792,000 0 792,000 272,630 792,000 0 792,000 272,630 792,000 0 792,000 272,630 32 0.333 792,000 4,359,375 5,151,375 1,713,294 792,000 4,359,375 5,151,375 1,713,294 792,000 0 792,000 263,411 792,000 0 792,000 263,411 33 0.321 792,000 0 792,000 254,503 792,000 0 792,000 254,503 792,000 0 792,000 254,503 792,000 0 792,000 254,503 34 0.310 792,000 4,359,375 5,151,375 1,599,379 792,000 4,359,375 5,151,375 1,599,379 792,000 0 792,000 245,897 792,000 0 792,000 245,897 35 0.300 792,000 0 792,000 237,582 792,000 0 792,000 237,582 792,000 0 792,000 237,582 792,000 0 792,000 237,582 36 0.290 792,000 4,359,375 5,151,375 1,493,037 792,000 4,359,375 5,151,375 1,493,037 792,000 0 792,000 229,548 792,000 0 792,000 229,548 37 0.280 792,000 0 792,000 221,785 792,000 0 792,000 221,785 792,000 0 792,000 221,785 792,000 0 792,000 221,785 38 0.271 792,000 4,359,375 5,151,375 1,393,766 792,000 4,359,375 5,151,375 1,393,766 792,000 0 792,000 214,285 792,000 0 792,000 214,285 39 0.261 792,000 0 792,000 207,039 792,000 0 792,000 207,039 792,000 0 792,000 207,039 792,000 0 792,000 207,039 40 0.253 792,000 4,359,375 5,151,375 1,301,095 792,000 4,359,375 5,151,375 1,301,095 792,000 19,237,500 20,029,500 5,058,900 792,000 19,237,500 20,029,500 5,058,900 41 0.244 792,000 0 792,000 193,273 792,000 0 792,000 193,273 792,000 0 792,000 193,273 792,000 0 792,000 193,273 42 0.236 792,000 4,359,375 5,151,375 1,214,587 792,000 4,359,375 5,151,375 1,214,587 792,000 0 792,000 186,737 792,000 0 792,000 186,737 43 0.228 792,000 0 792,000 180,422 792,000 0 792,000 180,422 792,000 0 792,000 180,422 792,000 0 792,000 180,422 44 0.220 792,000 4,359,375 5,151,375 1,133,830 792,000 4,359,375 5,151,375 1,133,830 792,000 0 792,000 174,321 792,000 0 792,000 174,321 45 0.213 792,000 0 792,000 168,426 792,000 0 792,000 168,426 792,000 0 792,000 168,426 792,000 0 792,000 168,426 46 0.205 792,000 4,359,375 5,151,375 1,058,442 792,000 4,359,375 5,151,375 1,058,442 792,000 0 792,000 162,731 792,000 0 792,000 162,731 47 0.199 792,000 0 792,000 157,228 792,000 0 792,000 157,228 792,000 0 792,000 157,228 792,000 0 792,000 157,228 48 0.192 792,000 4,359,375 5,151,375 988,067 792,000 4,359,375 5,151,375 988,067 792,000 0 792,000 151,911 792,000 0 792,000 151,911 49 0.185 792,000 0 792,000 146,774 792,000 0 792,000 146,774 792,000 0 792,000 146,774 792,000 0 792,000 146,774 PV 23,935,039 52,053,541 315,000 PV 23,935,039 58,784,791 315,000 PV 23,935,039 46,606,206 315,000 PV 23,935,039 54,256,206 315,000 PV

B & C - COSTS T groynes Client/Authority Bournemouth Borough Council / Borough of Poole Project name Poole Bay and Harbour Strategy Study Project reference WCPBHS Base date for estimates (year 0) Jun-2004 Scaling factor (e.g. £m, £k, £) £ Discount rate 3.5%

D1 (100m Rock Groynes 2-yearly Beach D2 (100m Rock Groynes 2-yearly Beach E1 (100m Rock Groynes 10-yearly Beach E2 (100m Rock Groynes 10-yearly Beach Recharge - assuming Capital Swash Channel Recharge - assuming no Capital Swash Recharge - assuming Capital Swash Channel Recharge - assuming no Capital Swash Dredging) TOTALS:Channel Dredging) TOTALS:Dredging) TOTALS:Channel Dredging) TOTALS:

cash sum 22,227,799 11,816,000 845,000 34,888,799 25,945,441 22,227,799 16,118,375 845,000 39,191,174 30,247,816 22,227,799 12,135,000 1,115,000 35,477,799 24,228,489 22,227,799 18,505,000 1,115,000 41,847,799 30,598,489 Discount year Factor 0 1.000 7,337,752 1,730,250 315,000 9,383,002 9,383,002 7,337,752 6,032,625 315,000 13,685,377 13,685,377 7,337,752 2,460,000 315,000 10,112,752 10,112,752 7,337,752 8,830,000 315,000 16,482,752 16,482,752 1 0.966 0 0 0 0 0 0 0 0 0 0 0000 00 2 0.934 0 1,708,625 1,708,625 1,595,020 0 1,708,625 1,708,625 1,595,020 0 0 0000 00 3 0.902 0 0 0 0 0 0 0 0 0 0 0000 00 4 0.871 0 1,708,625 1,708,625 1,488,968 0 1,708,625 1,708,625 1,488,968 0 0 0000 00 5 0.842 0 0 0 0 0 0 0 0 0 0 0000 00 6 0.814 0 1,708,625 1,708,625 1,389,968 0 1,708,625 1,708,625 1,389,968 0 0 0000 00 7 0.786 0 0 0 0 0 0 0 0 0 0 0000 00 8 0.759 0 1,708,625 1,708,625 1,297,550 0 1,708,625 1,708,625 1,297,550 0 0 0000 00 9 0.734 0 0 0 0 0 0 0 0 0 0 0000 00 10 0.709 7,860,294 209,250 265,000 8,334,544 5,908,515 7,860,294 209,250 265,000 8,334,544 5,908,515 7,860,294 3,022,500 265,000 11,147,794 7,902,881 7,860,294 3,022,500 265,000 11,147,794 7,902,881 11 0.685 0 0 0 0 0 0 0 0 0 0 0000 00 12 0.662 0 209,250 209,250 138,478 0 209,250 209,250 138,478 0 0 0000 00 13 0.639 0 0 0 0 0 0 0 0 0 0 0000 00 14 0.618 0 209,250 209,250 129,271 0 209,250 209,250 129,271 0 0 0000 00 15 0.597 0 0 0 0 0 0 0 0 0 0 0000 00 16 0.577 0 209,250 209,250 120,676 0 209,250 209,250 120,676 0 0 0000 00 17 0.557 0 0 0 0 0 0 0 0 0 0 0000 00 18 0.538 0 209,250 209,250 112,652 0 209,250 209,250 112,652 0 0 0000 00 19 0.520 0 0 0 0 0 0 0 0 0 0 0000 00 20 0.503 7,029,752 147,000 265,000 7,441,752 3,739,971 7,029,752 147,000 265,000 7,441,752 3,739,971 7,029,752 2,217,500 265,000 9,512,252 4,780,534 7,029,752 2,217,500 265,000 9,512,252 4,780,534 21 0.486 0 0 0 0 0 0 0 0 0 0 0000 00 22 0.469 0 147,000 147,000 68,965 0 147,000 147,000 68,965 0 0 0000 00 23 0.453 0 0 0 0 0 0 0 0 0 0 0000 00 24 0.438 0 147,000 147,000 64,380 0 147,000 147,000 64,380 0 0 0000 00 25 0.423 0 0 0 0 0 0 0 0 0 0 0000 00 26 0.409 0 147,000 147,000 60,099 0 147,000 147,000 60,099 0 0 0000 00 27 0.395 0 0 0 0 0 0 0 0 0 0 0000 00 28 0.382 0 147,000 147,000 56,103 0 147,000 147,000 56,103 0 0 0000 00 29 0.369 0 0 0 0 0 0 0 0 0 0 0000 00 30 0.356 0 147,000 147,000 52,373 0 147,000 147,000 52,373 0 2,217,500 135,000 2,352,500 838,145 0 2,217,500 135,000 2,352,500 838,145 31 0.344 0 0 0 0 0 0 0 0 0 0 0000 00 32 0.333 0 147,000 147,000 48,891 0 147,000 147,000 48,891 0 0 0000 00 33 0.321 0 0 0 0 0 0 0 0 0 0 0000 00 34 0.310 0 147,000 147,000 45,640 0 147,000 147,000 45,640 0 0 0000 00 35 0.300 0 0 0 0 0 0 0 0 0 0 0000 00 36 0.290 0 147,000 147,000 42,605 0 147,000 147,000 42,605 0 0 0000 00 37 0.280 0 0 0 0 0 0 0 0 0 0 0000 00 38 0.271 0 147,000 147,000 39,773 0 147,000 147,000 39,773 0 0 0000 00 39 0.261 0 0 0 0 0 0 0 0 0 0 0000 00 40 0.253 0 147,000 147,000 37,128 0 147,000 147,000 37,128 0 2,217,500 135,000 2,352,500 594,177 0 2,217,500 135,000 2,352,500 594,177 41 0.244 0 0 0 0 0 0 0 0 0 0 0000 00 42 0.236 0 147,000 147,000 34,660 0 147,000 147,000 34,660 0 0 0000 00 43 0.228 0 0 0 0 0 0 0 0 0 0 0000 00 44 0.220 0 147,000 147,000 32,355 0 147,000 147,000 32,355 0 0 0000 00 45 0.213 0 0 0 0 0 0 0 0 0 0 0000 00 46 0.205 0 147,000 147,000 30,204 0 147,000 147,000 30,204 0 0 0000 00 47 0.199 0 0 0 0 0 0 0 0 0 0 0000 00 48 0.192 0 147,000 147,000 28,196 0 147,000 147,000 28,196 0 0 0000 00 49 0.185 0 0 0 0 0 0 0 0 0 0 0000 00 PV 16,442,977 8,866,421 636,043 PV 16,442,977 13,168,796 636,043 PV 16,442,977 7,067,274 718,238 PV 16,442,977 13,437,274 718,238 PV

D & E - COSTS R groynes Client/Authority Bournemouth Borough Council / Borough of Poole Project name Poole Bay and Harbour Strategy Study Project reference WCPBHS Base date for estimates (year 0) Jun-2004 Scaling factor (e.g. £m, £k, £) £ Discount rate 3.5% F3 (150m Rock Groynes 2-yearly Beach F4 (150m Rock Groynes 2-yearly Beach F1 (150m Rock Groynes 2-yearly Beach F2 (150m Rock Groynes 2-yearly Beach Recharge - assuming Capital Swash Channel Recharge - assuming no Capital Swash Recharge - assuming Capital Swash Channel Recharge - assuming no Capital Swash Dredging) (based on existing contruction Channel Dredging) (based on existing Dredging) TOTALS:Channel Dredging) TOTALS:costs) TOTALS:contruction costs) TOTALS:

cash sum 16,386,154 13,004,325 1,385,000 30,775,479 22,550,115 16,386,154 16,904,438 1,385,000 34,675,592 26,450,228 12,364,200 13,004,325 1,385,000 26,753,525 19,527,228 12,364,200 16,904,438 1,385,000 30,653,638 23,427,340 Discount year Factor 0 1.000 5,675,515 1,588,275 315,000 7,578,790 7,578,790 5,675,515 5,488,388 315,000 11,478,902 11,478,902 4,283,300 1,588,275 315,000 6,186,575 6,186,575 4,283,300 5,488,388 315,000 10,086,688 10,086,688 1 0.966 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0.934 0 1,650,263 135,000 1,785,263 1,666,562 0 1,650,263 135,000 1,785,263 1,666,562 0 1,650,263 135,000 1,785,263 1,666,562 0 1,650,263 135,000 1,785,263 1,666,562 3 0.902 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4 0.871 0 1,650,263 135,000 1,785,263 1,555,753 0 1,650,263 135,000 1,785,263 1,555,753 0 1,650,263 135,000 1,785,263 1,555,753 0 1,650,263 135,000 1,785,263 1,555,753 5 0.842 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 6 0.814 0 1,650,263 135,000 1,785,263 1,452,312 0 1,650,263 135,000 1,785,263 1,452,312 0 1,650,263 135,000 1,785,263 1,452,312 0 1,650,263 135,000 1,785,263 1,452,312 7 0.786 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 8 0.759 0 1,650,263 135,000 1,785,263 1,403,200 0 1,650,263 135,000 1,785,263 1,403,200 0 1,650,263 135,000 1,785,263 1,403,200 0 1,650,263 135,000 1,785,263 1,403,200 9 0.734 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 10 0.709 5,851,515 217,800 265,000 6,334,315 4,490,515 5,851,515 217,800 265,000 6,334,315 4,490,515 4,459,300 217,800 265,000 4,942,100 3,503,548 4,459,300 217,800 265,000 4,942,100 3,503,548 11 0.685 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 12 0.662 0 217,800 217,800 144,136 0 217,800 217,800 144,136 0 217,800 217,800 144,136 0 217,800 217,800 144,136 13 0.639 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 14 0.618 0 217,800 217,800 134,553 0 217,800 217,800 134,553 0 217,800 217,800 134,553 0 217,800 217,800 134,553 15 0.597 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 16 0.577 0 217,800 217,800 125,607 0 217,800 217,800 125,607 0 217,800 217,800 125,607 0 217,800 217,800 125,607 17 0.557 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 18 0.538 0 217,800 217,800 117,255 0 217,800 217,800 117,255 0 217,800 217,800 117,255 0 217,800 217,800 117,255 19 0.520 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 20 0.503 4,859,124 248,400 265,000 5,372,524 2,794,549 4,859,124 248,400 265,000 5,372,524 2,794,549 3,621,600 248,400 265,000 4,135,000 2,150,844 3,621,600 248,400 265,000 4,135,000 2,150,844 21 0.486 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 22 0.469 0 248,400 248,400 116,537 0 248,400 248,400 116,537 0 248,400 248,400 116,537 0 248,400 248,400 116,537 23 0.453 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 24 0.438 0 248,400 248,400 108,789 0 248,400 248,400 108,789 0 248,400 248,400 108,789 0 248,400 248,400 108,789 25 0.423 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 26 0.409 0 248,400 248,400 101,555 0 248,400 248,400 101,555 0 248,400 248,400 101,555 0 248,400 248,400 101,555 27 0.395 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 28 0.382 0 248,400 248,400 94,803 0 248,400 248,400 94,803 0 248,400 248,400 94,803 0 248,400 248,400 94,803 29 0.369 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 30 0.356 0 248,400 248,400 91,597 0 248,400 248,400 91,597 0 248,400 248,400 91,597 0 248,400 248,400 91,597 31 0.344 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 32 0.333 0 248,400 248,400 82,615 0 248,400 248,400 82,615 0 248,400 248,400 82,615 0 248,400 248,400 82,615 33 0.321 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 34 0.310 0 248,400 248,400 77,122 0 248,400 248,400 77,122 0 248,400 248,400 77,122 0 248,400 248,400 77,122 35 0.300 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 36 0.290 0 248,400 248,400 71,994 0 248,400 248,400 71,994 0 248,400 248,400 71,994 0 248,400 248,400 71,994 37 0.280 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 38 0.271 0 248,400 248,400 67,208 0 248,400 248,400 67,208 0 248,400 248,400 67,208 0 248,400 248,400 67,208 39 0.261 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 40 0.253 0 248,400 248,400 62,739 0 248,400 248,400 62,739 0 248,400 248,400 62,739 0 248,400 248,400 62,739 41 0.244 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 42 0.236 0 248,400 248,400 58,568 0 248,400 248,400 58,568 0 248,400 248,400 58,568 0 248,400 248,400 58,568 43 0.228 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 44 0.220 0 248,400 248,400 54,673 0 248,400 248,400 54,673 0 248,400 248,400 54,673 0 248,400 248,400 54,673 45 0.213 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 46 0.205 0 248,400 248,400 51,038 0 248,400 248,400 51,038 0 248,400 248,400 51,038 0 248,400 248,400 51,038 47 0.199 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 48 0.192 0 248,400 248,400 47,645 0 248,400 248,400 47,645 0 248,400 248,400 47,645 0 248,400 248,400 47,645 49 0.185 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 PV 12,265,794 9,047,216 1,092,055 PV 12,265,794 12,947,328 1,092,055 PV 9,264,674 9,047,216 1,092,055 PV 9,264,674 12,947,328 1,092,055

F - COSTS R groynes Client/Authority Bournemouth Borough Council / Borough of Poole Project name Poole Bay and Harbour Strategy Study Project reference WCPBHS Base date for estimates (year 0) Jun-2004 Scaling factor (e.g. £m, £k, £) £ Discount rate 3.5%

G3 (150m Rock Groynes 10-yearly Beach Recharge - G4 (150m Rock Groynes 10-yearly Beach Recharge - G1 (150m Rock Groynes 10-yearly Beach Recharge - G2 (150m Rock Groynes 10-yearly Beach Recharge - assuming Capital Swash Channel Dredging) (based on assuming no Capital Swash Channel Dredging) (based on assuming Capital Swash Channel Dredging) TOTALS: assuming no Capital Swash Channel Dredging) TOTALS: existing contruction costs) TOTALS: existing contruction costs) TOTALS:

Control Professional Control Professional Control Professional Control Professional Beach Recharge Cash PV Beach Recharge Cash PV Beach Recharge Cash PV Beach Recharge Cash PV Structures Services Structures Services Structures Services Structures Services

cash sum 16,386,154 17,775,000 1,115,000 35,276,154 22,379,884 16,386,154 23,996,250 1,115,000 41,497,404 28,601,134 12,364,200 17,775,000 1,115,000 31,254,200 19,356,996 12,364,200 23,996,250 1,115,000 37,475,450 25,578,246 Discount year Factor 0 1.000 5,675,515 2,407,500 315,000 8,398,015 8,398,015 5,675,515 8,628,750 315,000 14,619,265 14,619,265 4,283,300 2,407,500 315,000 7,005,800 7,005,800 4,283,300 8,628,750 315,000 13,227,050 13,227,050 1 0.966 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0.934 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 0.902 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4 0.871 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 5 0.842 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 6 0.814 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 7 0.786 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 8 0.759 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 9 0.734 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 10 0.709 5,851,515 3,195,000 265,000 9,311,515 6,601,108 5,851,515 3,195,000 265,000 9,311,515 6,601,108 4,459,300 3,195,000 265,000 7,919,300 5,614,141 4,459,300 3,195,000 265,000 7,919,300 5,614,141 11 0.685 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 12 0.662 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 13 0.639 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 14 0.618 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 0.597 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 16 0.577 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 17 0.557 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 18 0.538 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 19 0.520 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 20 0.503 4,859,124 4,057,500 265,000 9,181,624 4,775,874 4,859,124 4,057,500 265,000 9,181,624 4,775,874 3,621,600 4,057,500 265,000 7,944,100 4,132,169 3,621,600 4,057,500 265,000 7,944,100 4,132,169 21 0.486 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 22 0.469 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 23 0.453 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 24 0.438 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 25 0.423 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 26 0.409 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 27 0.395 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 28 0.382 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 29 0.369 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 30 0.356 0 4,057,500 135,000 4,192,500 1,545,977 0 4,057,500 135,000 4,192,500 1,545,977 0 4,057,500 135,000 4,192,500 1,545,977 0 4,057,500 135,000 4,192,500 1,545,977 31 0.344 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 32 0.333 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 33 0.321 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 34 0.310 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 35 0.300 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 36 0.290 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 37 0.280 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 38 0.271 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 39 0.261 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 40 0.253 0 4,057,500 135,000 4,192,500 1,058,910 0 4,057,500 135,000 4,192,500 1,058,910 0 4,057,500 135,000 4,192,500 1,058,910 0 4,057,500 135,000 4,192,500 1,058,910 41 0.244 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 42 0.236 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 43 0.228 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 44 0.220 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 45 0.213 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 46 0.205 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 47 0.199 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 48 0.192 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 49 0.185 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 PV 12,265,794 9,182,069 718,238 PV 12,265,794 15,403,319 718,238 PV 9,264,674 9,182,069 718,238 PV 9,264,674 15,403,319 718,238 PV

G - COSTS R groynes Client/Authority Bournemouth Borough Council / Borough of Poole Project name Poole Bay and Harbour Strategy Study Project reference WCPBHS Base date for estimates (year 0) Jun-2004 Scaling factor (e.g. £m, £k, £) £ Discount rate 3.5%

H3 (Rock Offshore Breakwaters 10-yearly Beach Recharge - H4 (Rock Offshore Breakwaters 2-yearly Beach Recharge - H1 (Rock Offshore Breakwaters 10-yearly Beach Recharge - H2 (Rock Offshore Breakwaters 10-yearly Beach Recharge - assuming Capital Swash Channel Dredging) (assuming losses assuming Capital Swash Channel Dredging) (assuming losses assuming Capital Swash Channel Dredging) TOTALS: assuming no Capital Swash Channel Dredging) TOTALS: limited to those of 150m rock groynes) TOTALS: limited to those of 150m rock groynes) TOTALS:

Beach Beach Professional Control Structures Professional Services Cash PV Control Structures Cash PV Control Structures Beach Recharge Professional Services Cash PV Control Structures Beach Recharge Professional Services Cash PV Recharge Recharge Services

cash sum 45,168,000 40,345,313 1,115,000 86,628,313 58,045,016 45,168,000 47,995,313 1,115,000 94,278,313 65,695,016 45,168,000 17,775,000 1,115,000 64,058,000 42,754,314 45,168,000 13,004,325 1,115,000 59,287,325 42,619,460 Discount year Factor 0 1.000 13,350,000 10,574,063 315,000 24,239,063 24,239,063 13,350,000 18,224,063 315,000 31,889,063 31,889,063 13,350,000 2,407,500 315,000 16,072,500 16,072,500 13,350,000 1,588,275 315,000 15,253,275 15,253,275 1 0.966 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0.934 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1,650,263 0 1,650,263 1,540,538 3 0.902 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4 0.871 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1,650,263 0 1,650,263 1,438,108 5 0.842 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 6 0.814 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1,650,263 0 1,650,263 1,342,490 7 0.786 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 8 0.759 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1,650,263 0 1,650,263 1,253,228 9 0.734 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 10 0.709 17,026,000 8,477,813 265,000 25,768,813 18,267,996 17,026,000 8,477,813 265,000 25,768,813 18,267,996 17,026,000 3,195,000 265,000 20,486,000 14,522,911 17,026,000 217,800 265,000 17,508,800 12,412,318 11 0.685 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 12 0.662 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 217,800 0 217,800 144,136 13 0.639 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 14 0.618 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 217,800 0 217,800 134,553 15 0.597 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 16 0.577 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 217,800 0 217,800 125,607 17 0.557 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 18 0.538 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 217,800 0 217,800 117,255 19 0.520 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 20 0.503 14,792,000 7,097,813 265,000 22,154,813 11,134,253 14,792,000 7,097,813 265,000 22,154,813 11,134,253 14,792,000 4,057,500 265,000 19,114,500 9,606,296 14,792,000 248,400 265,000 15,305,400 7,691,972 21 0.486 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 22 0.469 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 248,400 0 248,400 116,537 23 0.453 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 24 0.438 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 248,400 0 248,400 108,789 25 0.423 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 26 0.409 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 248,400 0 248,400 101,555 27 0.395 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 28 0.382 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 248,400 0 248,400 94,803 29 0.369 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 30 0.356 0 7,097,813 135,000 7,232,813 2,576,895 0 7,097,813 135,000 7,232,813 2,576,895 0 4,057,500 135,000 4,192,500 1,493,697 0 248,400 135,000 383,400 136,597 31 0.344 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 32 0.333 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 248,400 0 248,400 82,615 33 0.321 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 34 0.310 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 248,400 0 248,400 77,122 35 0.300 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 36 0.290 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 248,400 0 248,400 71,994 37 0.280 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 38 0.271 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 248,400 0 248,400 67,208 39 0.261 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 40 0.253 0 7,097,813 135,000 7,232,813 1,826,809 0 7,097,813 135,000 7,232,813 1,826,809 0 4,057,500 135,000 4,192,500 1,058,910 0 248,400 135,000 383,400 96,836 41 0.244 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 42 0.236 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 248,400 0 248,400 58,568 43 0.228 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 44 0.220 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 248,400 0 248,400 54,673 45 0.213 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 46 0.205 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 248,400 0 248,400 51,038 47 0.199 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 48 0.192 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 248,400 0 248,400 47,645 49 0.185 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 PV 32,854,006 24,472,771 718,238 PV 32,854,006 32,122,771 718,238 PV 32,854,006 9,182,069 718,238 PV 32,854,006 9,047,216 718,238 PV

H - COSTS R reefs Client/Authority Bournemouth Borough Council / Borough of Poole Project name Poole Bay and Harbour Strategy Study Project reference WCPBHS Base date for estimates (year 0) Jun-2004 Scaling factor (e.g. £m, £k, £) £ Discount rate 3.5%

I1 (Geotextile Offshore Breakwaters 10-yearly Beach Recharge - I2 (Geotextile Offshore Breakwaters 10-yearly Beach Recharge - I3 (Geotextile Offshore Breakwaters 2-yearly Beach Recharge - assuming I4 (Geotextile Offshore Breakwaters 10-yearly Beach Recharge - assuming assuming Capital Swash Channel Dredging) (50% renewal after 20 assuming Capital Swash Channel Dredging) (100% renewal after 20 Capital Swash Channel Dredging) (50% renewal after 20 years) (assuming Capital Swash Channel Dredging) (50% renewal after 20 years) (assuming years) TOTALS: years) TOTALS: losses limited to those of 150m rock groynes) TOTALS: losses limited to those of 150m rock groynes) TOTALS:

Control Control Structures Beach Recharge Professional Services Cash PV Beach Recharge Professional Services Cash PV Control Structures Beach Recharge Professional Services Cash PV Control Structures Beach Recharge Professional Services Cash PV Structures

cash sum 23,640,439 40,345,313 1,375,000 65,360,752 39,565,352 37,611,024 40,345,313 1,375,000 79,331,337 45,624,219 23,640,439 13,004,325 1,915,000 38,559,764 24,437,370 23,640,439 17,775,000 1,375,000 42,790,439 24,183,260 Discount year Factor 0 1.000 4,383,658 10,574,063 315,000 15,272,720 15,272,720 5,483,658 10,574,063 315,000 16,372,720 16,372,720 4,383,658 1,588,275 315,000 6,286,933 6,286,933 4,383,658 2,407,500 315,000 7,106,158 7,106,158 1 0.966 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0.934 0 0 0 0 0 0 0 0 0 1,650,263 135,000 1,785,263 1,666,562 0 0 0 0 3 0.902 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4 0.871 0 0 0 0 0 0 0 0 0 1,650,263 135,000 1,785,263 1,555,753 0 0 0 0 5 0.842 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 6 0.814 0 0 0 0 0 0 0 0 0 1,650,263 135,000 1,785,263 1,452,312 0 0 0 0 7 0.786 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 8 0.759 0 0 0 0 0 0 0 0 0 1,650,263 135,000 1,785,263 1,403,200 0 0 0 0 9 0.734 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 10 0.709 5,636,131 8,477,813 265,000 14,378,944 10,193,504 6,912,131 8,477,813 265,000 15,654,944 11,098,084 5,636,131 217,800 265,000 6,118,931 4,337,825 5,636,131 3,195,000 265,000 9,096,131 6,448,419 11 0.685 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 12 0.662 0 0 0 0 0 0 0 0 0 217,800 217,800 144,136 0 0 0 0 13 0.639 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 14 0.618 0 0 0 0 0 0 0 0 0 217,800 217,800 134,553 0 0 0 0 15 0.597 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 16 0.577 0 0 0 0 0 0 0 0 0 217,800 217,800 125,607 0 0 0 0 17 0.557 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 18 0.538 0 0 0 0 0 0 0 0 0 217,800 217,800 117,255 0 0 0 0 19 0.520 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 20 0.503 7,201,723 7,097,813 265,000 14,564,536 7,575,826 10,185,552 7,097,813 265,000 17,548,365 9,127,882 7,201,723 248,400 265,000 7,715,123 4,013,065 7,201,723 4,057,500 265,000 11,524,223 5,994,390 21 0.486 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 22 0.469 0 0 0 0 0 0 0 0 0 248,400 248,400 116,537 0 0 0 0 23 0.453 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 24 0.438 0 0 0 0 0 0 0 0 0 248,400 248,400 108,789 0 0 0 0 25 0.423 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 26 0.409 0 0 0 0 0 0 0 0 0 248,400 248,400 101,555 0 0 0 0 27 0.395 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 28 0.382 0 0 0 0 0 0 0 0 0 248,400 248,400 94,803 0 0 0 0 29 0.369 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 30 0.356 2,818,066 7,097,813 265,000 10,180,878 3,754,180 5,636,131 7,097,813 265,000 12,998,944 4,793,337 2,818,066 248,400 265,000 3,331,466 1,228,472 2,818,066 4,057,500 265,000 7,140,566 2,633,070 31 0.344 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 32 0.333 0 0 0 0 0 0 0 0 0 248,400 248,400 82,615 0 0 0 0 33 0.321 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 34 0.310 0 0 0 0 0 0 0 0 0 248,400 248,400 77,122 0 0 0 0 35 0.300 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 36 0.290 0 0 0 0 0 0 0 0 0 248,400 248,400 71,994 0 0 0 0 37 0.280 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 38 0.271 0 0 0 0 0 0 0 0 0 248,400 248,400 67,208 0 0 0 0 39 0.261 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 40 0.253 3,600,862 7,097,813 265,000 10,963,674 2,769,122 9,393,552 7,097,813 265,000 16,756,365 4,232,196 3,600,862 248,400 265,000 4,114,262 1,039,149 3,600,862 4,057,500 265,000 7,923,362 2,001,223 41 0.244 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 42 0.236 0 0 0 0 0 0 0 0 0 248,400 248,400 58,568 0 0 0 0 43 0.228 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 44 0.220 0 0 0 0 0 0 0 0 0 248,400 248,400 54,673 0 0 0 0 45 0.213 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 46 0.205 0 0 0 0 0 0 0 0 0 248,400 248,400 51,038 0 0 0 0 47 0.199 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 48 0.192 0 0 0 0 0 0 0 0 0 248,400 248,400 47,645 0 0 0 0 49 0.185 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 PV 13,912,052 24,472,771 797,389 PV 19,883,293 24,472,771 797,389 PV 13,912,052 9,047,216 1,253,401 PV 13,912,052 9,182,069 797,389 PV

I - COSTS Gtx reefs (1of2) Client/Authority Bournemouth Borough Council / Borough of Poole Project name Poole Bay and Harbour Strategy Study Project reference WCPBHS Base date for estimates (year 0) Jun-2004 Scaling factor (e.g. £m, £k, £) £ Discount rate 3.5% I5 (Geotextile Offshore Breakwaters 10-yearly I6 (Geotextile Offshore Breakwaters 10-yearly Beach Recharge - assuming no Capital Swash Beach Recharge - assuming no Capital Swash Channel Dredging) (50% renewal after 20 Channel Dredging) (100% renewal after 20 years) TOTALS:years) TOTALS:

Control Beach Professional Control Beach Professional Cash PV Cash PV Structures Recharge Services Structures Recharge Services

cash sum 23,640,439 47,995,313 1,375,000 73,010,752 47,215,352 37,611,024 47,995,313 1,375,000 86,981,337 53,274,219 Discount year Factor 0 1.000 4,383,658 18,224,063 315,000 22,922,720 22,922,720 5,483,658 18,224,063 315,000 24,022,720 24,022,720 1 0.966 0 0 0 0 0 0 0 0 2 0.934 0 0 0 0 0 0 0 0 3 0.902 0 0 0 0 0 0 0 0 4 0.871 0 0 0 0 0 0 0 0 5 0.842 0 0 0 0 0 0 0 0 6 0.814 0 0 0 0 0 0 0 0 7 0.786 0 0 0 0 0 0 0 0 8 0.759 0 0 0 0 0 0 0 0 9 0.734 0 0 0 0 0 0 0 0 10 0.709 5,636,131 8,477,813 265,000 14,378,944 10,193,504 6,912,131 8,477,813 265,000 15,654,944 11,098,084 11 0.685 0 0 0 0 0 0 0 0 12 0.662 0 0 0 0 0 0 0 0 13 0.639 0 0 0 0 0 0 0 0 14 0.618 0 0 0 0 0 0 0 0 15 0.597 0 0 0 0 0 0 0 0 16 0.577 0 0 0 0 0 0 0 0 17 0.557 0 0 0 0 0 0 0 0 18 0.538 0 0 0 0 0 0 0 0 19 0.520 0 0 0 0 0 0 0 0 20 0.503 7,201,723 7,097,813 265,000 14,564,536 7,575,826 10,185,552 7,097,813 265,000 17,548,365 9,127,882 21 0.486 0 0 0 0 0 0 0 0 22 0.469 0 0 0 0 0 0 0 0 23 0.453 0 0 0 0 0 0 0 0 24 0.438 0 0 0 0 0 0 0 0 25 0.423 0 0 0 0 0 0 0 0 26 0.409 0 0 0 0 0 0 0 0 27 0.395 0 0 0 0 0 0 0 0 28 0.382 0 0 0 0 0 0 0 0 29 0.369 0 0 0 0 0 0 0 0 30 0.356 2,818,066 7,097,813 265,000 10,180,878 3,754,180 5,636,131 7,097,813 265,000 12,998,944 4,793,337 31 0.344 0 0 0 0 0 0 0 0 32 0.333 0 0 0 0 0 0 0 0 33 0.321 0 0 0 0 0 0 0 0 34 0.310 0 0 0 0 0 0 0 0 35 0.300 0 0 0 0 0 0 0 0 36 0.290 0 0 0 0 0 0 0 0 37 0.280 0 0 0 0 0 0 0 0 38 0.271 0 0 0 0 0 0 0 0 39 0.261 0 0 0 0 0 0 0 0 40 0.253 3,600,862 7,097,813 265,000 10,963,674 2,769,122 9,393,552 7,097,813 265,000 16,756,365 4,232,196 41 0.244 0 0 0 0 0 0 0 0 42 0.236 0 0 0 0 0 0 0 0 43 0.228 0 0 0 0 0 0 0 0 44 0.220 0 0 0 0 0 0 0 0 45 0.213 0 0 0 0 0 0 0 0 46 0.205 0 0 0 0 0 0 0 0 47 0.199 0 0 0 0 0 0 0 0 48 0.192 0 0 0 0 0 0 0 0 49 0.185 0 0 0 0 0 0 0 0 PV 13,912,052 32,122,771 797,389 PV 19,883,293 32,122,771 797,389 PV

I - COSTS Gtx reefs (2of2) Client/Authority Poole Bay & Harbour Strategy Study Project name Poole Bay - PBY1 Project reference WCPBHS Base date for estimates (year 0) Jun-2004 Scaling factor (e.g. £m, £k, £) £ Discount rate 3.5% 1.0 m/yr (plus 10m buffer) 0.5 m/yr (plus 10m buffer) Residential Commercial Utilities Tourism TOTALS PV Residential Commercial Utilities Tourism TOTALS PV cash sum 204,899,149 3,476,660 2,698,000 129,600,900 340,674,709 175,452,208 113,368,066 2,805,661 1,403,000 129,600,900 247,177,628 130,088,748 Discount year Factor 0 1.000 22,837,846 1,779,551 1,378,000 2,592,018 28,587,415 28,587,415 22,837,846 1,779,551 1,378,000 2,592,018 28,587,415 28,587,415 1 0.966 955,368 0 0 2,592,018 3,547,386 3,427,426 0 0 0 2,592,018 2,592,018 2,504,365 2 0.934 1,546,786 61,329 0 2,592,018 4,200,133 3,920,869 955,368 0 0 2,592,018 3,547,386 3,311,523 3 0.902 1,355,713 3,433 0 2,592,018 3,951,163 3,563,723 1,273,824 0 0 2,592,018 3,865,842 3,486,768 4 0.871 1,041,806 0 0 2,592,018 3,633,824 3,166,668 272,962 61,329 0 2,592,018 2,926,309 2,550,109 5 0.842 896,226 0 0 2,592,018 3,488,244 2,937,008 0 3,433 0 2,592,018 2,595,451 2,185,300 6 0.814 14,275,928 0 0 2,592,018 16,867,946 13,722,085 1,355,713 0 0 2,592,018 3,947,731 3,211,482 7 0.786 318,456 0 0 2,592,018 2,910,474 2,287,606 495,882 0 0 2,592,018 3,087,900 2,427,061 8 0.759 0 33,563 0 2,592,018 2,625,581 1,993,896 545,925 0 0 2,592,018 3,137,943 2,382,990 9 0.734 6,346,373 0 0 2,592,018 8,938,391 6,558,375 177,425 0 0 2,592,018 2,769,443 2,032,026 10 0.709 15,103,914 0 0 2,592,018 17,695,932 12,544,979 718,801 0 0 2,592,018 3,310,819 2,347,102 11 0.685 5,773,153 0 0 2,592,018 8,365,171 5,729,688 7,956,851 0 0 2,592,018 10,548,869 7,225,403 12 0.662 3,089,023 0 0 2,592,018 5,681,041 3,759,618 6,319,077 0 0 2,592,018 8,911,095 5,897,214 13 0.639 545,925 5,340 0 2,592,018 3,143,282 2,009,828 318,456 0 0 2,592,018 2,910,474 1,860,969 14 0.618 864,381 585,825 0 2,592,018 4,042,224 2,497,212 0 0 0 2,592,018 2,592,018 1,601,302 15 0.597 4,522,075 0 0 2,592,018 7,114,093 4,246,336 0 0 0 2,592,018 2,592,018 1,547,151 16 0.577 3,139,066 0 0 2,592,018 5,731,084 3,305,150 0 33,563 0 2,592,018 2,625,581 1,514,188 17 0.557 4,863,278 0 0 2,592,018 7,455,296 4,154,119 1,433,052 0 0 2,592,018 4,025,070 2,242,784 18 0.538 2,606,790 32,037 25,000 2,592,018 5,255,845 2,829,543 4,913,321 0 0 2,592,018 7,505,339 4,040,583 19 0.520 1,087,300 0 0 2,592,018 3,679,318 1,913,818 13,193,178 0 0 2,592,018 15,785,196 8,210,759 20 0.503 9,342,135 144,931 0 2,592,018 12,079,083 6,070,535 1,910,736 0 0 2,592,018 4,502,754 2,262,931 21 0.486 0 0 0 2,592,018 2,592,018 1,258,609 5,227,228 0 0 2,592,018 7,819,246 3,796,798 22 0.469 45,494 18,536 0 2,592,018 2,656,048 1,246,086 545,925 0 0 2,592,018 3,137,943 1,472,168 23 0.453 864,381 0 0 2,592,018 3,456,399 1,566,736 1,501,293 0 0 2,592,018 4,093,311 1,855,439 24 0.438 8,493,677 0 0 2,592,018 11,085,695 4,855,059 1,587,731 0 0 2,592,018 4,179,749 1,830,551 25 0.423 3,771,429 141,117 0 2,592,018 6,504,564 2,752,387 545,925 5,340 0 2,592,018 3,143,282 1,330,070 26 0.409 7,688,438 0 0 2,592,018 10,280,456 4,203,038 0 0 0 2,592,018 2,592,018 1,059,715 27 0.395 3,628,124 247,145 0 2,592,018 6,467,287 2,554,658 318,456 0 0 2,592,018 2,910,474 1,149,673 28 0.382 6,733,070 0 0 2,592,018 9,325,088 3,558,960 545,925 585,825 0 2,592,018 3,723,768 1,421,192 29 0.369 1,314,768 0 0 2,592,018 3,906,786 1,440,620 545,925 0 0 2,592,018 3,137,943 1,157,111 30 0.356 2,791,039 0 0 2,592,018 5,383,057 1,917,867 3,976,151 0 0 2,592,018 6,568,169 2,340,097 31 0.344 177,425 0 0 2,592,018 2,769,443 953,326 864,381 0 0 2,592,018 3,456,399 1,189,797 32 0.333 3,389,282 11,900 0 2,592,018 5,993,199 1,993,276 2,274,686 0 0 2,592,018 4,866,704 1,618,616 33 0.321 1,205,583 0 0 2,592,018 3,797,601 1,220,332 2,406,618 0 0 2,592,018 4,998,636 1,606,275 34 0.310 9,687,887 83,907 0 2,592,018 12,363,812 3,838,668 2,456,661 0 0 2,592,018 5,048,679 1,567,494 35 0.300 2,413,442 7,292 1,135,000 2,592,018 6,147,752 1,844,183 1,660,521 0 0 2,592,018 4,252,539 1,275,663 36 0.290 5,017,957 0 0 2,592,018 7,609,975 2,205,620 946,269 32,037 25,000 2,592,018 3,595,325 1,042,043 37 0.280 13,097,641 99,392 160,000 2,592,018 15,949,051 4,466,238 1,087,300 0 0 2,592,018 3,679,318 1,030,325 38 0.271 177,425 0 0 2,592,018 2,769,443 749,306 0 0 0 2,592,018 2,592,018 701,301 39 0.261 673,307 4,043 0 2,592,018 3,269,368 854,654 1,332,966 144,931 0 2,592,018 4,069,915 1,063,927 40 0.253 1,437,601 46,149 0 2,592,018 4,075,768 1,029,427 8,009,169 0 0 2,592,018 10,601,187 2,677,568 41 0.244 2,229,192 7,170 0 2,592,018 4,828,380 1,178,276 0 0 0 2,592,018 2,592,018 632,534 42 0.236 3,764,605 15,942 0 2,592,018 6,372,565 1,502,518 0 0 0 2,592,018 2,592,018 611,144 43 0.228 1,473,996 144,931 0 2,592,018 4,210,945 959,278 0 0 0 2,592,018 2,592,018 590,477 44 0.220 1,530,864 3,127 0 2,592,018 4,126,009 908,144 45,494 18,536 0 2,592,018 2,656,048 584,602 45 0.213 7,656,592 0 0 2,592,018 10,248,610 2,179,462 545,925 0 0 2,592,018 3,137,943 667,312 46 0.205 4,210,443 0 0 2,592,018 6,802,461 1,397,687 318,456 0 0 2,592,018 2,910,474 598,009 47 0.199 5,254,524 0 0 2,592,018 7,846,542 1,557,693 318,456 0 0 2,592,018 2,910,474 577,786 48 0.192 1,214,682 0 0 2,592,018 3,806,700 730,150 8,175,221 0 0 2,592,018 10,767,239 2,065,226 49 0.185 4,444,736 0 0 2,592,018 7,036,754 1,304,053 3,452,973 141,117 0 2,592,018 6,186,108 1,146,411

Table 3.11 Damages on Collapse of Seawall Damage Cost Calculation Sheet - Do Nothing (Linear) Client/Authority Poole Bay & Harbour Strategy Study Project name Poole Bay - PBY1 Project reference WCPBHS Base date for estimates (year 0) Jun-2004 Scaling factor (e.g. £m, £k, £) £ Discount rate 3.5% <>PV breach/failure £ 175,452,208 Year 0102049 Breach pb 0.100 0.630 1.000 1.000 PV Total Damage £ 156,374,425 (calculated below) Year Discount Prob of a Prob that breach/failure: PV damage due to: Other PV factor breach/ occurs in has not breach or failure over- damage total damage failure year occurred topping (specify) 0 1.000 0.100 0.100 0.900 17,545,221 0 17,545,221 1 0.966 0.153 0.138 0.762 23,342,772 0 23,342,772 2 0.934 0.206 0.157 0.605 25,720,019 0 25,720,019 3 0.902 0.259 0.157 0.449 24,807,556 0 24,807,556 4 0.871 0.312 0.140 0.309 21,395,215 0 21,395,215 5 0.842 0.365 0.113 0.196 16,638,073 0 16,638,073 6 0.814 0.418 0.082 0.114 11,690,143 0 11,690,143 7 0.786 0.471 0.054 0.060 7,407,081 0 7,407,081 8 0.759 0.524 0.032 0.029 4,211,849 0 4,211,849 9 0.734 0.577 0.017 0.012 2,132,966 0 2,132,966 10 0.709 0.630 0.008 0.004 951,806 0 951,806 11 0.685 0.667 0.003 0.001 360,243 0 360,243 12 0.662 0.704 0.001 0.000 122,334 0 122,334 13 0.639 0.741 0.000 0.000 36,825 0 36,825 14 0.618 0.778 0.000 0.000 9,675 0 9,675 15 0.597 0.815 0.000 0.000 2,174 0 2,174 16 0.577 0.852 0.000 0.000 406 0 406 17 0.557 0.889 0.000 0.000 61 0 61 18 0.538 0.926 0.000 0.000 7 0 7 19 0.520 0.963 0.000 0.000 1 0 1 20 0.503 1.000 0.000 0.000 0 0 0 21 0.486 1.000 0.000 0.000 0 0 0 22 0.469 1.000 0.000 0.000 0 0 0 23 0.453 1.000 0.000 0.000 0 0 0 24 0.438 1.000 0.000 0.000 0 0 0 25 0.423 1.000 0.000 0.000 0 0 0 26 0.409 1.000 0.000 0.000 0 0 0 27 0.395 1.000 0.000 0.000 0 0 0 28 0.382 1.000 0.000 0.000 0 0 0 29 0.369 1.000 0.000 0.000 0 0 0 30 0.356 1.000 0.000 0.000 0 0 0 31 0.344 1.000 0.000 0.000 0 0 0 32 0.333 1.000 0.000 0.000 0 0 0 33 0.321 1.000 0.000 0.000 0 0 0 34 0.310 1.000 0.000 0.000 0 0 0 35 0.300 1.000 0.000 0.000 0 0 0 36 0.290 1.000 0.000 0.000 0 0 0 37 0.280 1.000 0.000 0.000 0 0 0 38 0.271 1.000 0.000 0.000 0 0 0 39 0.261 1.000 0.000 0.000 0 0 0 40 0.253 1.000 0.000 0.000 0 0 0 41 0.244 1.000 0.000 0.000 0 0 0 42 0.236 1.000 0.000 0.000 0 0 0 43 0.228 1.000 0.000 0.000 0 0 0 44 0.220 1.000 0.000 0.000 0 0 0 45 0.213 1.000 0.000 0.000 0 0 0 46 0.205 1.000 0.000 0.000 0 0 0 47 0.199 1.000 0.000 0.000 0 0 0 48 0.192 1.000 0.000 0.000 0 0 0 49 0.185 1.000 0.000 0.000 0 0 0

Total 156,374,425 0 156,374,425

Notes Complete one spreadsheet for the 'do nothing' option The formulae assume that breach probability will be constant to the first year entered and after the last year with linear variation between It is assumed that breaches are not repaired and that once breach damage has occurred it will not recur. A separate check should be made to ensure that overtopping damages do not exceed write off values. These damage calculations assume that overtopping damage can reasonably be ignored once a breach has occurred. If these assumptions are not valid then appropriate adjustments need to be made. In this case the total damage is calculated as: PV damage in year=disc factor*((prob no breach damage in year*annual overtop damage)+(prob breach damage in year*breach damage))

Table 3.12 Damages under the Do Nothing scenario Damage Cost Calculation Sheet - Do Nothing (Linear) Client/Authority Poole Bay & Harbour Strategy Study Project name Poole Bay - PBY1 Project reference WCPBHS Base date for estimates (year 0) Jun-2004 Scaling factor (e.g. £m, £k, £) £ Discount rate 3.5% <>PV breach/failure £ 175,452,208 Year 0102049 Breach pb 0.010 0.010 0.010 0.010 PV Total Damage £ 35,982,524 (calculated below) Year Discount Prob of a Prob that breach/failure: PV damage due to: Other PV factor breach/ occurs in has not breach or failure over- damage total damage failure year occurred topping (specify) 0 1.000 0.010 0.010 0.990 1,754,522 0 1,754,522 1 0.966 0.010 0.010 0.980 1,678,239 0 1,678,239 2 0.934 0.010 0.010 0.970 1,605,272 0 1,605,272 3 0.902 0.010 0.010 0.961 1,535,477 0 1,535,477 4 0.871 0.010 0.010 0.951 1,468,717 0 1,468,717 5 0.842 0.010 0.010 0.941 1,404,860 0 1,404,860 6 0.814 0.010 0.009 0.932 1,343,779 0 1,343,779 7 0.786 0.010 0.009 0.923 1,285,354 0 1,285,354 8 0.759 0.010 0.009 0.914 1,229,469 0 1,229,469 9 0.734 0.010 0.009 0.904 1,176,014 0 1,176,014 10 0.709 0.010 0.009 0.895 1,124,883 0 1,124,883 11 0.685 0.010 0.009 0.886 1,075,975 0 1,075,975 12 0.662 0.010 0.009 0.878 1,029,193 0 1,029,193 13 0.639 0.010 0.009 0.869 984,446 0 984,446 14 0.618 0.010 0.009 0.860 941,644 0 941,644 15 0.597 0.010 0.009 0.851 900,703 0 900,703 16 0.577 0.010 0.009 0.843 861,542 0 861,542 17 0.557 0.010 0.008 0.835 824,083 0 824,083 18 0.538 0.010 0.008 0.826 788,254 0 788,254 19 0.520 0.010 0.008 0.818 753,982 0 753,982 20 0.503 0.010 0.008 0.810 721,200 0 721,200 21 0.486 0.010 0.008 0.802 689,844 0 689,844 22 0.469 0.010 0.008 0.794 659,850 0 659,850 23 0.453 0.010 0.008 0.786 631,161 0 631,161 24 0.438 0.010 0.008 0.778 603,719 0 603,719 25 0.423 0.010 0.008 0.770 577,471 0 577,471 26 0.409 0.010 0.008 0.762 552,363 0 552,363 27 0.395 0.010 0.008 0.755 528,347 0 528,347 28 0.382 0.010 0.008 0.747 505,376 0 505,376 29 0.369 0.010 0.007 0.740 483,403 0 483,403 30 0.356 0.010 0.007 0.732 462,385 0 462,385 31 0.344 0.010 0.007 0.725 442,282 0 442,282 32 0.333 0.010 0.007 0.718 423,052 0 423,052 33 0.321 0.010 0.007 0.711 404,659 0 404,659 34 0.310 0.010 0.007 0.703 387,065 0 387,065 35 0.300 0.010 0.007 0.696 370,236 0 370,236 36 0.290 0.010 0.007 0.689 354,139 0 354,139 37 0.280 0.010 0.007 0.683 338,741 0 338,741 38 0.271 0.010 0.007 0.676 324,013 0 324,013 39 0.261 0.010 0.007 0.669 309,926 0 309,926 40 0.253 0.010 0.007 0.662 296,451 0 296,451 41 0.244 0.010 0.007 0.656 283,562 0 283,562 42 0.236 0.010 0.007 0.649 271,233 0 271,233 43 0.228 0.010 0.006 0.643 259,440 0 259,440 44 0.220 0.010 0.006 0.636 248,160 0 248,160 45 0.213 0.010 0.006 0.630 237,371 0 237,371 46 0.205 0.010 0.006 0.624 227,050 0 227,050 47 0.199 0.010 0.006 0.617 217,178 0 217,178 48 0.192 0.010 0.006 0.611 207,736 0 207,736 49 0.185 0.010 0.006 0.605 198,704 0 198,704

Total 35,982,524 0 35,982,524

Table 3.13 Residual Damages under the 1:100 year Standard of Protection Client/Authority Poole Bay & Harbour Strategy Study Project name Poole Bay - PBY1 Project reference WCPBHS Base date for estimates (year 0) Jun-2004 Scaling factor (e.g. £m, £k, £) £ (used for all costs, losses and benefits) Principle land use band A (A to E) Discount rate 3.5% Costs and benefits of options Costs and benefits £ Open Beach Timber Groynes 100m Rock Groynes 150m Rock Groynes 100m Rock Offshore Breakwaters Geotxtile Offshore Breakwaters Do Nothing A3 (Open Beach A4 (Open Beach C1 (Timber Groynes B2 (Timber Groynes E1 (100m Rock E2 (100m Rock G3 (150m Rock G2 (150m Rock H3 (Rock Offshore H1 (Rock Offshore H2 (Rock Offshore I4 (Geotextile I1 (Geotextile I6 (Geotextile Offshore Recharge - assumingRecharge - assuming 10-yearly Beach 2-yearly Beach Groynes 10-yearly Groynes 10-yearly Groynes 10-yearly Groynes 10-yearly Breakwaters 10- Breakwaters 10- Breakwaters 10- Offshore Offshore Breakwaters 10-yearly Capital Swash no Capital Swash Recharge - assumingRecharge - assuming Beach Recharge - Beach Recharge - Beach Recharge - Beach Recharge - yearly Beach yearly Beach yearly Beach Breakwaters 10- Breakwaters 10- Beach Recharge - Channel Dredging) Channel Dredging) Capital Swash no Capital Swash assuming Capital assuming no Capital assuming Capital assuming no Capital Recharge - assumingRecharge - assumingRecharge - assuming yearly Beach yearly Beach assuming no Capital (minus 50% in (plus 50% in Channel Dredging) Channel Dredging) Swash Channel Swash Channel Swash Channel Swash Channel Capital Swash Capital Swash no Capital Swash Recharge - assumingRecharge - assuming Swash Channel recharge volumes) recharge volumes) Dredging) Dredging) Dredging) (based on Dredging) Channel Dredging) Channel Dredging) Channel Dredging) Capital Swash Capital Swash Dredging) (100% existing contruction (assuming losses Channel Dredging) Channel Dredging) renewal after 20 years) costs) limited to those of (50% renewal after (50% renewal after 150m rock groynes) 20 years) (assuming 20 years) losses limited to those of 150m rock groynes)

PV costs PVc (net of OB) 0 36,230,899 92,639,246 70,856,245 83,034,830 24,228,489 30,598,489 19,356,996 28,601,134 42,754,314 58,045,016 65,695,016 24,183,260 39,565,352 53,274,219 Optimism Bias 46% 46% 46% 46% 48% 48% 48% 48% 48% 48% 48% 49% 49% 49% PV costs PVc (including of OB) 52,897,113 135,253,299 103,450,117 121,230,852 35,858,163 45,285,763 28,648,355 42,329,678 63,276,384 85,906,623 97,228,623 36,033,057 58,952,375 79,378,586 PV damage PVd 156,374,425 35,982,524 35,982,524 35,982,524 35,982,524 35,982,524 35,982,524 35,982,524 35,982,524 35,982,524 35,982,524 35,982,524 35,982,524 35,982,524 35,982,524 Total PV benefits PVb 120,391,902 120,391,902 120,391,902 120,391,902 120,391,902 120,391,902 120,391,902 120,391,902 120,391,902 120,391,902 120,391,902 120,391,902 120,391,902 120,391,902 Net Present Value NPV 84,161,002 27,752,656 49,535,657 37,357,072 96,163,413 89,793,413 101,034,905 91,790,768 77,637,588 62,346,886 54,696,886 96,208,642 80,826,549 67,117,683 Average benefit/cost ratio 2.28 0.89 1.16 0.99 3.36 2.66 4.20 2.84 1.90 1.40 1.24 3.34 2.04 1.52 - ----Highest b/c ------

Note: The Incremental benefit/cost ratios for each 1:100 yr scheme have been calculated with respect to the "Maintain Existing Defences" option, not the 1:300yr option immediately to the left

Economic Score total Economic Score 3.55 0.00 1.33 0.00 5.71 4.32 7.40 4.69 2.81 1.80 1.48 5.68 3.08 2.03

Residential Properties 672 672 673 674 675 676 677 678 679 679 679 680 680 680 Base Score 0.95 0.37 0.49 0.42 1.41 1.12 1.77 1.20 0.80 0.59 0.52 1.42 0.87 0.64 People Score Public Safety Score 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Vulnerability Score 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

total People Score 0.95 0.37 0.49 0.42 1.41 1.12 1.77 1.20 0.80 0.59 0.52 1.42 0.87 0.64

SSSI protected area (ha): 8888888888888 8 Other designated areas (ha): 37 37 37 37 37 37 37 37 37 37 37 37 37 37 National BAP habitat gain (ha): 0000000000000 0 Environmental Score Total Habitat Score: 0.02 0.01 0.01 0.01 0.03 0.03 0.04 0.03 0.02 0.01 0.01 0.03 0.02 0.02 No of Grade 1 or SM: 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 No of Grade 2: 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

total Environmental Score 0.02 0.01 0.01 0.01 0.03 0.03 0.04 0.03 0.02 0.01 0.01 0.03 0.02 0.02

Total Priorisation Score TOTAL 4.5 0.4 1.8 0.4 7.2 5.5 9.2 5.9 3.6 2.4 2.0 7.1 4.0 2.7 0.54 0.71 0.61 2.09 1.66 2.62 1.78 1.19 0.88 0.96

Notes: 1) Benefits will normally be expressed either in terms of damage avoided or asset values protected. Care is needed to avoid double counting

2) PV damage avoided is calculated as PV damage (No Project) - PV damage (Option) PV asset protection benefits are calculated as PVa (Option) - PVa (No Project) PV benefits calculated as PV damage avoided + PV asset protection benefits 3) Incremental benefit/cost ratio is calculated as: (PVb(current option) - PVb(previous option))/(PVc(current option) - PVc(previous option))

Summary of Economic Appraisal 100,000,000

90,000,000

80,000,000

70,000,000

60,000,000

50,000,000 Cost (£)

40,000,000

30,000,000

20,000,000

10,000,000

0 Open Beach Timber groynes 100m Rock Groynes 150m Rock Groynes Rock Offshore Geotextile Offshore Breakwaters Breakwaters Options