Innerleithen Consultation Event #1

Borders Flood Studies

How is flood risk managed by the Scottish Borders Council? • The Flood Risk Management (Scotland) Act 2009 aims to prioritise flood mitigation across Scotland using a proactive and risk based process for assessing flood risk. • This approach led to the preparation of SEPA’s Flood Risk Management Strategies by SEPA and the Tweed Local Flood Risk Management Plan developed by the Scottish Borders Council as the Lead Local Authority for the Tweed Local Plan District. • These plans identified specific communities as being at risk and in need of a detailed flood study to help inform the management of flood risk in each community.

Which communities are being assessed? • Broughton, Peebles & Innerleithen • Newcastleton Borders Scheme • Earlston Flood considered Flood Risk Studies against Management (2017-18) national Strategy and priorities How will Flood Protection Potentially Local Flood (2018/19) Schemes be prioritised? Vulnerable Risk Areas Management • SEPA will prioritise nationally where National Plan (2016) funding should be allocated. Flood Risk • The reports and findings of our Assessment (2011) study will inform this process. Flood Risk Management (Scotland) Act 2009 What are the study objectives?

1) Develop better understanding of flood risk in the community • Create, update or develop new/existing flood model information; • Determine existing flood risk; Why choose a 200 year • Develop improved flood mapping; standard of protection? • Scottish Planning Policy 2) Develop recommendations for management of flood risk requires new build • Develop a range of options to manage flood risk, including structural and properties to have a 200 non-structural options; year standard of protection • Appraise actions to manage flood risk (consider the pros and cons and • This standard is an accepted economic viability for all proposed options); as low risk by the flood • Recommend options for the future management of flood risk; insurance companies. • A higher standard of 3) Select a preferred approach to manage flood risk in each protection will mean the community and identify recommendations that the Council will scheme will be considered take forward more favourably by SEPA’s • SEPA will prioritise nationally where funding should be allocated; scheme prioritisation • The reports and findings of our study will inform this process. making funding more likely

4) Engage partners and stakeholders • Today’s consultation. What has been done so far?

The studies aim to better assess current flood risks in the community by undertaking a review of past flood events; generating updated and detailed flood maps, determining the likely risk to different properties; and to propose a set of mitigation measures to reduce the flood risk to an acceptable level. Flood Review Topographic Asset The models developed form a basis for assessing surveys inspections future flood levels, flood mitigation options, detailed design of schemes and the costs to deliver.

Return periods and annual probabilities

doff •When a river floods the severity of the flood is known as a 1 in x year flood. This Hydrology Modelling Flood Mapping terminology represents the probability of that event occurring in any year. •For reference, the December 2015 event (Storm Frank) in Peebles had a 1 in 55 chance of occurring in any year. •This does not mean that the flood will occur once every 55 years; it could occur tomorrow and again next week, or not for another 200 years. But on average a flood of that severity will occur once every 55 years. Properties at Options Cost-Benefit •For example, there is a 1 in 100 (or 1%) risk Appraisal chance of a flood exceeding the 100 year flood in any one year. Flood Timeline

2002 Flooding on 2016 1948 Montgomery Large flood events “Torrential Street, at least downpours left on the River Tweed 2012 one house was several streets in in Peebles. River SEPA reported inundated. Innerleithen Tweed ‘17 feet flooding in the Flooding of Princes under a foot of above normal’. The Innerleithen Street from the water” Border low lying parts of Leithen Water. area. Peebles was Telegraph inundated. Photo courtesy of Margaret Maxwell via Border Telegraph

1940 1950 1960 1970 1980 1990 2000 2010 2020

2005 1994 SEPA commented 2015 Flooding at the general area was Walkerburn was Montgomery subject to flooding impacted by the flood Street, at least from the River event on the 5th and th one house was Tweed. Other 30 December with inundated sources of flooding various non-residential attributed to the properties located on Leithen Water. the floodplain flooded (E.g. Rugby Club and fishing hut).

Photo courtesy of M Mconnachie of SEPA Catchment & watercourses assessed

Innerleithen is at flood risk from the Leithen Water and Chapman’s Burn. Flood risk to properties from the River Tweed was assessed and found to be minimal. Innerleithen is the much larger of the two assessed watercourses with a catchment area of 58 km2. Chapman’s Burn, with a catchment area of just 0.7 km2, is a small watercourse which is culverted for the majority of its length. Chapman’s Burn is predicated to flood more frequently than the Leithen Water. The figures below shows the watercourses catchment’s and the length of modelled channel.

Return Chapman's Chapman's Burn Leithen Water at Period Burn FPS At Tweed Tweed (Years) inlet (m3/s) confluence confluence (m3/s) (m3/s) 2 0.18 0.99 25.90 50 2.39 3.18 62.39 200 3.32 4.42 84.97 Flood mapping – Leithen Water

Property Type Number at Risk (1 in 200 year flood) Residential 37 Commercial 11

How do we create these flood maps? • A physical survey captured the measurements of river channels, banks and structures along each watercourse. • These measurements were input into a computer model, along with calculated river flows for a range of storm events. • This model produced a flood level which was then applied to a 3D representation of the land surface and buildings. The outcome resulted in a detailed flood map of river flooding in Broughton

What do the maps show? • The mapping indicates the predicted flooding for a given flood magnitude. • The 1 in 10 year map shows what is expected to be inundated for a flood that is likely to occur once every 10 years (or with a probability of 10% in any one year). • The 1 in 200 year represents a flood event with a probability of 0.5% in any year. Flood mechanisms & key constraints on Leithen Water

Out of bank flow paths, key structures and constraints were identified. Flood flow from the Leithen Water is first seen along Princes Street, south of Chambers Street and proceeds to flow east along Montgomery Street. As the water level continues to rise flood water escapes from the west bank immediately upstream of the A72 Road Bridge. This water flows west along High Street and effects numerous properties.

Has this flow mechanism been seen before? The only known flood which overtopped the Leithen Water banks’ is the 1948 flood, however the details on this event are limited. Since 1948 Innerleithen has developed considerably. The aim of the scheme is to be proactive and mitigate against floods like or in excess of the Complex out of Existing walls Bridges that 1948 flood. bank flows constrain flows Can we remove the gravel?

1) Is gravel causing a flood risk problem? In the past gravel in some watercourses in the Border towns was intermittently removed. Furthermore, in some locations it is believed that gravel and the bed level of rivers is rising as a result of a long term build up of gravel. Whilst gravel does build up locally, these deposits are not new and the formation and erosion of gravel in Innerleithen is a natural process balanced over thousands of years. 2) Why is sediment in rivers important? River sediment and their movements form important habitats for plants, fish and animals. The removal of sediment can lead to a loss of, or damage to these habitats. Sediment removal can disturb the natural equilibrium of a river which can cause serious problems with river stability, often leading to erosion downstream. 3) Would removal of gravel reduce the flood risk? While sediment removal appears a straight forward solution to flooding, evidence indicates that it does not work on large rivers moving at pace. Our assessment has shown that flood levels could be reduced if the bed level was lowered by 0.5m. However, during a flood, the water will move material downstream and deposit in any lowered sections, filling the section back to its original level very quickly. This was observed in the Bowmont Water in August 2009 when the river level was lowered by 1m; it was refilled after a flood by September. The reasons why wide-scale bed modification is not actively undertaken are as follows: • Any additional conveyance created by a lowered river channel is therefore very quickly lost. • It is not considered a sustainable option; expensive repeat works are required to maintain bed levels. • Additional bank stabilisation works may also be required. In many locations unsightly concrete walls may be needed or removal of riparian land (gardens) and extensive rock armour. • Lowering the bed level on the Leithen Water would require a significant and regular removal of sediment via the local road network. • Sediment removal carried out in watercourses requires regulatory legislation enforced by SEPA and would require sufficient evidence to support any such applications for removal. 4) What else could be done? We have looked at a number of other options to mitigate the flood risks on the Leithen Water, including options for natural flood management in the upper catchment that may help to manage the sediment transport into the downstream reaches. Further modelling is required to investigate the benefits of these options. Leithen Water Options appraisal – Long list of options

The process for selecting options assesses a wide range of possible options, which are narrowed down to a short list according to whether the options are technically, environmentally and socially acceptable. Those that are short listed are shown in the following posters. The full list of options assessed is provided below. • Relocation - Relocation or abandonment of properties not usually socially or politically viable. • Flood Warning – The existing flood warning system on the Leithen Water should be developed further. • Resilience Measures - Unlikely to be economically viable due to number of properties at risk. • Resistance Measures – Property level protection is well suited to defend against shallow flood depths • Diversion channel – Insufficient available space. • Watercourse Maintenance – Council should continue the scheduled maintenance regime. • Demountable Defences – A permanent wall is more suitable due to limited warning time. • Storage – Option investigated but discounted due to lack of a suitable location. • Natural Flood Management – NFM opportunities throughout the Leithen Water catchment have been identified. • Structure Modification – Bridges or culverts restrict flow on both watercourses which contributes to flood risk but removing the bridges is not sufficient to prevent flooding by itself. A coarse debris screen located upstream of the town could help to prevent future blockage of bridges from floating flood debris. • Direct Defences – A combination of walls and/or embankments can contain flow to the watercourse. • Channel Modification – Insufficient space to widen the channel, deepening the channel is unsustainable.

Least desirable options Good practice and partial solutions Most desirable options Leithen Water– Short Listed Options

Option 1: Option 2: Property Level Protection Construct flood walls (PLP) • This option provides a 200 year standard of protection to those properties who • Automatic property level protection would flood above floor level for the 200 year event. This keeps the wall to the installed in 47 properties (of 48) to minimum length and avoids placing a wall across numerous gardens. protect against the 200 year flood • Average wall height between 450 mm and 900 mm with freeboard. event. PLP shall involve surveying • Total combined wall length 450m. each property to identify entry • Raise footbridge by Montgomery Street by approximately 400 mm. points and recommend appropriate • Includes installation of in channel coarse debris PLP, but could include self sealing screen. door and air vents and non return • Climate change adaptation would require valves on plumbing. significantly longer walls and raising of road • Estimated cost £1.5m bridge. • Estimated damage avoided £5.1m • Estimated cost £1.2m • Estimated damage avoided £5.2m

Typical example of a flood wall

See adjacent technical drawings for Proposed flood wall plan Typical example of PLP further option details Option 1 - Property level Protection – Leithen Water

PLP is the last form of defence before water gets into the building. Automatic PLP is proposed for each residential property - 36 in total and 11 non Standard of protection map residential properties. It can protect these properties to the 200 year flood event. The standard of protection (SOP) map indicates the existing level of protection to each property in the flood study.

Option appraisal and first round of public consultation October 2018

Examples of how Property Level Protection can mitigate the risks of flood inundation (image courtesy of Whitehouse Construction Co. Ltd) B709 OPTION SUMMARY. Construction of direct defences along the PEEBLES ROAD length of the Leithen Water to the alignments shown. Defences to be set back where possible, but constrained by road and BOND STREET property boundaries. Option based on the 1 in 200 year flood. Innerleithen The current layout is the minimum wall length required to protect properties which currently flood to a depth above floor level. LEITHEN ROAD LEITHEN Flooding to gardens and depths below floor level are anticipated. HORSBRUGH TERRACE Option 2: Leithen Water LEITHEN WATER 200 Year Direct Defences HORSBRUGH STREET GEORGE STREET A72

APPROXIMATELY 120m LONG FLOOD WALL UPSTREAM OF A72 B709 ROADBRIDGE HEIGHT APPROXIMATELY 0.65m BRIDGEND

QUEEN STREET

A A BUCCLEUCH STREET

A72 HORSBRUGH STREET

PRINCESS STREET

LEITHEN CRESENT LEGEND A72 ROADBRIDGE WALL DEFENCE A72 ROAD BRIDGE FLOOD WALL WITH RAILING ON TOP EXISTING WATERCOURSE

BUCCLEUCH STREET CHAMBERS STREET SE

LEITHEN WATER

LEITHEN WATER HORSBRUGH STREET 200 YEAR WATER LEVEL

PRINCESS STREET

LEITHEN CRESENT BUCCLEUCH STREET

CHAMBERS STREET

SECTION A-A 1:50 APPROXIMATELY 70m LONG FLOOD WALL HEIGHT APPROXIMATELY 0.3m - 0.9m Comments Background mapping transparency reduced P02 PRINCESS STREET

Rev.: Date 02/10/18 Drawn BH Designed JG Checked Approved Client Approval

BUCCLEUCH STREET A - Approved LEITHEN CRESENT B - Approved with Revisions C - Do Not Use

LEITHEN WATER FLOOD WALL WITH Purpose of Issue Status B PRINCESS STREET RAILING ON TOP Suitable for Coordination S1 MONTGOMERY STREET

B 200 YEAR WATER Unit 2.1 LEVEL Quantum Court Research Avenue South Heriot Watt University Edinburgh EH14 4AP FLOODWALL TO TIE INTO RAISED United Kingdom FOOTBRIDGE.MONTGOMERY FOOTBRIDGE STREET APPROXIMATELY 120m LONG FLOOD www.jbaconsulting.com SOFFIT TO BE RAISED BY 0.385m WALL UPSTREAM OF FOOTBRIDGE t +44 (0)131 3192940 HEIGHT APPROXIMATELY 0.35m - 0.75m f +44 (0)845 8627772 e [email protected] LEITHEN MILLS PRINCESS STREET Offices at Coleshill, Doncaster, Edinburgh, Exeter, Glasgow, Haywards Heath, Isle of Man, Leeds, Limerick, Newcastle upon Tyne, Newport, Peterborough, Saltaire, Skipton, Tadcaster, Thirsk, Wallingford and Warrington

Project APPROXIMATELY 40m LONG FLOOD WALL DOWNSTREAM OF FOOTBRIDGE Borders Flood Studies HEIGHT APPROXIMATELY 0.45m

Title WAVERLEY MILLS Innerleithen Leithen Water: Option 2 200 Year direct defences APPROXIMATELY 40m LONG FLOOD for WALL DOWNSTREAM OF FOOTBRIDGE Client HEIGHT APPROXIMATELY 0.45m SECTION B-B 1:50

CRAIGERNE LANE The property of this drawing and design vested in Jeremy Benn Associates Ltd. It shall not be reproduced in whole or in part, nor disclosed to a third party, without the prior written consent of Jeremy Benn Associates Ltd.

Scale Drawn: B Henderson 20/09/18 This map is reproduced from Ordnance Survey material with the permission of the Ordnance Survey on behalf of the Designed: J Garrett 19/09/18 controller of Her Majesty's Stationery Office. Unauthorized reproduction infringes Crown Copyright and may lead to As Shown @ A1 prosecution or civil proceedings. © Crown copyright and database rights (2018) Ordnance Survey (100023423) Checked: Approved: PLAN Project Number: 2017s5526 Drawing Number Revision 1:1000 AEM-JBAU-IL-LW-IM-C-1401 P02 OPTION SUMMARY. Construction of direct defences along the length of the Leithen Water to the alignments shown. Defences to be set back where possible, but constrained by road and LEITHEN WATER Innerleithen property boundaries. Option based on the 1 in 200 year flood with an allowance for climate change. Reductions in wall heights would be possible if a lower standard was selected or if Option 2: Leithen Water the inclusion of climate change was omitted and addressed later LEITHEN ROAD through alternative measures.

NURSERY PARK A72 200 Year + Climate Change

STRAND DAMSIDE

B709 A72

LEITHEN WATER Direct Defences

DAMSIDE

LEITHEN ROAD

PEEBLES ROAD

CHURCH STREET WALL ON LEITHEN ROAD UPSTREAM OF A72 LEITHEN WATER ROADBRIDGE RIGHT BANK APPROX. 317m LONG. HEIGHT VARIES FROM 0.76m TO 1.6m

B709 CHURCH STREET

A72

LEITHEN ROAD LEITHEN CRAIG TERRACE

LEGEND

ST RONAN'S ROAD CRAIG TERRACE EXISTING GROUND LEVEL

APPROX. 0.9m APPROX. 1.6m 200 YEAR FLOOD LEVEL CHAPEL STREET B709 PEEBLES ROAD HIGH FLOODWALL HIGH FLOODWALL WITH STEEL 200+CC FLOOD LEVEL BOND STREET RAILINGS ON TOP WALL DEFENCE

PLORA CRES LEITHEN ROAD LEITHEN

HORSBRUGH TERRACE EXISTING WATERCOURSE

PLORA AVE

LEITHEN WATER

HORSBRUGH STREET GEORGE STREET A72

APPROX. 133m LONG. WALL PLORA AVENUE B709 UPSTREAM OF A72 ROADBRIDGE BRIDGEND HEIGHT APPROX. 1m QUEEN STREET BALLANTYNE STREET WALKER STREET

BUCCLEUCH STREET

A A A72 CHAPEL STREET HORSBRUGH STREET

CADDON COURT

PRINCESS STREET MATHIESON STREET

LEITHEN CRESENT

BALLANTYNE STREET A72 A72 ROADBRIDGE

GEORGE STREET SECTION A-A 1:200 MONTGOMERY STREET BUCCLEUCH STREET CHAMBERS STREET SE LEITHEN WATER

A72 LEITHEN WATER HORSBRUGH STREET PRIVATE CARAVAN PARK

WAVERLEY ROAD

PRINCESS STREET

GEORGE STREET

MONTGOMERY STREET

PRIVATE CARAVAN PARK LEITHEN CRESENT BUCCLEUCH STREET

MORNINGSIDE CHAMBERS STREET

WAVERLEY ROAD Comments Background mapping transparency reduced MONTGOMERY SQUARE P02 HORSBRUGH STREET

APPROX. 600m LONG LEFT BANK WALL Rev.: Date 02/10/18 Drawn BH Designed TF Checked AP Approved B DOWNSTREAM OF A72 ROADBRIDGE HEIGHT PRINCESS STREET VARIES APPROXIMATELY FROM 1m TO 1.5m Client Approval MONTGOMERY STREET A - Approved

BUCCLEUCH STREET APPROX. 490m LONG FLOOD WALL LEITHEN CRESENT B - Approved with Revisions

DOWNSTREAMWAVERLEY PLACE OF A72 ROADBRIDGE B LEITHEN WATER C - Do Not Use TO RIGHT BANK HEIGHT VARIES PRINCESS STREET FOOTBRIDGE MAY NEED RAISING MONTGOMERY STREET FROM APPROXIMATELY 1m TO 2m AS DECK LEVEL IS REACHED IN Purpose of Issue Status DEFENDED SCENARIO APPROX. 1.45m HIGH APPROX. 0.9m HIGH Suitable for Coordination S1 MILLER STREET FLOODWALL FLOODWALL WITH STEEL RAILINGS ON TOP MONTGOMERY STREET Unit 2.1 Quantum Court LEITHEN MILLS PRINCESS STREET Research Avenue South Heriot Watt University Edinburgh EH14 4AP United Kingdom www.jbaconsulting.com WAVERLEY MILLS t +44 (0)131 3192940 f +44 (0)845 8627772 e [email protected] TIE IN TO EXISTING DEFENCE Offices at Coleshill, Doncaster, Edinburgh, Exeter, Glasgow, Haywards Heath, Isle of Man, Leeds, Limerick, GATE/SLOPED ACCESS POINT (BRICK WALL) Newcastle upon Tyne, Newport, Peterborough, Saltaire, Skipton, Tadcaster, Thirsk, Wallingford and Warrington WAVERLEY MILLS

CRAIGERNEREQUIRED LANE FOR FOOTPATH ALONG LEITHEN WATER Project Borders Flood Studies APPROX. 52m WALL LEITHEN SECTION B-B CRESCENT / PRINCES STREET WALL LEITHEN CRESCENT / DOWNSTREAM RIGHT BANK 1:200 Title PRINCES STREET Innerleithen DOWNSTREAM LEFT BANK Leithen Water: Option 2 LEITHEN WATER

TWEEDBANK LEY 200 + CC Year direct defences for Client

TRAQUAIR ROAD

Scale Drawn: B Henderson 15/03/18 This map is reproduced from Ordnance Survey material with the permission of the Ordnance Survey on behalf of the Designed: T Fletcher 12/02/18 controller of Her Majesty's Stationery Office. Unauthorized reproduction infringes Crown Copyright and may lead to As Shown @ A1 prosecution or civil proceedings. © Crown copyright and database rights (2018) Ordnance Survey (100023423) Checked: A Pettit 16/07/18 TWEEDBANK LEY Approved: PLAN Project Number: 2017s5526 Drawing Number Revision 1:2000 AEM-JBAU-IL-LW-IM-C-1300 P02 Flood mapping – Chapman’s Burn

Property Type Number at Risk (1 in 200 year flood) Residential 23 Commercial 8

Out of bank flow paths, key structures and constraints were identified. Flood flow from Chapman’s Burn emerges from The culvert on St Ronan’s Terrace and at the entrance to the existing FPS culvert. Soon after the culvert’s manholes are surcharged in numerous places, starting with the manholes on Hall Street.

Improved flood estimation We are aware that flooding from the Chapman’s Burn watercourse or culvert has not been observed, therefore, we recommend the following short term options: • Installation of a flow gauge to provide a better flow estimates • Installation of telemetry to monitor water level • Improved channel Complex out of Culvert Culverts that conveyance bank flows condition constrain flow Chapman’s Burn options appraisal – long list of options

The process for selecting options assesses a wide range of possible options, which are narrowed down to a short list according to whether the options are technically, environmentally and socially acceptable. Those that are short listed are shown in the following posters. The full list of options assessed is provided below. • Relocation - Relocation or abandonment of properties not usually socially or politically viable. • Flood Warning – Flooding from Chapman’s Burn happens too quickly to provide sufficient warning. • Resilience Measures - Unlikely to be economically viable due to number of properties at risk. • Resistance Measures – Property level protection is well suited to shallow flood depths from both watercourses • Diversion channel – Insufficient available space. • Watercourse Maintenance – Council should continue the scheduled maintenance regime. • Demountable Defences – A permanent wall or embankment is more suitable than demountable defences. • Storage – Victoria Park could be utilised to temporally store water in a flood event. • Natural Flood Management – No additional NFM opportunities were identified in Chapman’s catchment. • Structure Modification – Upgrading the existing Flood Protection Scheme culvert can significantly reduce flood risk. • Direct Defences – A combination of walls or embankments can contain flows on the watercourses. • Channel Modification – Chapman’s Channel can be deepened to help contain the flow.

Least desirable options Good practice and partial solutions Most desirable options Chapman’s Burn– Short Listed Options

Option 1: Option 3: Property Level Protection Improve channel and culvert (PLP) conveyance • Automatic property level protection • 200 year standard of protection installed in 24 properties (of 31) to • Replacement of St Ronan's Terrace protect residential properties against culvert and deepening of Chapman’s the 200 year flood event. PLP shall Burn channel. involving surveying each property to • Replacement of existing Flood identify entry points and recommend Protection Scheme culvert with appropriate PLP, but could include enlarged culvert from inlet to outlet. self sealing door and air vents and • Approximately 1.1 km of culvert will be non return valves on plumbing. replaced running along Hall Street and • Estimated cost £0.6m Traquair Road. • Estimated damage avoided £2.4m • Estimated cost £6.5m Typical example of a new culvert • Estimated damage avoided £4.3m Option 4: Improve channel conveyance and off-line storage • 200 year standard of protection. • Replacement of St Ronan's Terrace culvert and deepening of Chapman’s Burn channel • Convert Victoria Park into a temporary storage basin during flood flows • Install non-return value on existing culvert and seal each manhole Estimated cost £3.4m • Estimated damage avoided £4.3m

Typical example of PLP See adjacent technical drawings Typical example of off-line storage for further option details Option 1 - Property level Protection – Chapman’s Burn

PLP is the last form of defence before water gets Standard of protection map into the building. Automatic PLP is proposed for each residential property - 23 in total and 1 non residential property. It can protect these properties to the 200 year flood event. The standard of protection (SOP) map indicates the existing level of protection to each property in the flood study.

Option appraisal and first round of public consultation October 2018

Examples of how Property Level Protection can mitigate the risks of flood inundation (image courtesy of Whitehouse Construction Co. Ltd) LEITHEN ROAD OPTION SUMMARY. Improve conveyance of open channel and upgrade existing FPS culvert to provide a 1 in 200 year standard. DAMSIDE Innerleithen

CHURCH STREET In this case the small culvert under St Ronans Terrace needs to LEITHEN WATER be upgraded to a 850 mm culvert.

B709 MAXWELL STREET CHAPEL STREET Upper headwall (ST Ronans Terrace) could be raised slightly to REPLACED HEADWALL CHURCH STREET Option 3: Chapmans Burn TO BE LEVEL WITH 170.77 mAOD + freeboard from 170.51 mAOD and low section TOP OF BANK on right and left bank filled to the same level. 200 Year Culvert Upgrade Drop channel over 10m on approach to FPS culvert inlet, raise FILL 5m LONG LOW RAISE 10m LONG right bank by approximately 150mm + freeboard in the region of LOW SPOT ON RIGHT ROAD LEITHEN SPOT ON RIGHT BANK A BANK BY 0.45m section Chap_009. UP TO 170.77mAOD Upgrade FPS culvert as shown in the table provided. NT32368901 B DROP CHANNEL BY & Improved Channel 0.59m AT CULVERT FACE AND TIE BACK A Inlet_0000 INTO EXISTING B XXX1 CHANNEL LEVEL 10m UPGRADE CULVERT CHAPEL STREET B709 Conveyance TO Ø825mm AND UPSTREAM

LOWER CULVERT BOND STREET INLET BY 0.87m TO

ACCOMMODATE ROAD LEITHEN

LARGER CULVERT HORSBRUGH TERRACE

LEITHEN WATER REPLACEMENT CULVERTS

HORSBRUGH STREET Manhole Existing Culverts Proposed Culverts XXX3 A72

ID Number Diameter (mm) Diameter (mm) B709 NT32368901 280 850 BRIDGEND Inlet_0000 300 1200 XXX5 XXX4 UPGRADE CULVERT BUCCLEUCH STREET XXX1 300 900 1138m TOTAL LENGTH A72 CHAPEL STREET XXX3 450 900

PRINCESS STREET LEITHEN CRESENT XXX4 450 900 A72 LEGEND XXX5 450 900 EXISTING GROUND LEVEL

XXX6 BUCCLEUCH STREET XXX6 450 900 FINISHED GROUND LEVEL XXX7 600 900 REPLACE EXISTING CULVERT WITH 200 YEAR FLOOD LEVEL XXX7 NEW CONCRETE UNITS SIZED ASA72 LEITHEN WATER XXX8 600 900 XXX8 SHOWN IN TABLE WAVERLEY ROAD UPGRADED CULVERT PRINCESS STREET XXX9 UTR 600 1200

XX10 600 1350 RAISED EMBANKMENT

PEEBLES ROAD XXX9 UTR XX11 UTR 600 1350 STORM WATER SEWER

LEITHEN CRESENT MORNINGSIDE HALL STREET XX12 UTR 600 1350 EXISTING WATERCOURSE

WAVERLEY ROAD XX13 UTR 600 1350 A72 MANHOLE / CULVERT INLET XX14 UTR 600 1350

XX15 600 1350 XX10 PRINCESS STREET

ST RONAN'S TERRACE XX11 UTR XX16 600 1500 LEITHEN CRESENT XX17 600 1500

WAVERLEY PLACE

A72 XX12 UTR XX18 600 1500

MILLER STREET XX19 UTR 675 1500

XX20 675 1500

XX21 675 1500 XX13 UTR LEITHEN MILLS

TRAQUAIR ROAD

MILLER STREET WAVERLEY MILLS XX14 UTR RIGHT BANK REPROFILED AND Comments Background mapping transparency reduced and manhole / culvert inlets altered

COWFORD COURT RAISED BY 0.45m P02 200 YEAR WATER LEVEL PEEBLES ROAD WAVERLEY MILLS Rev.: Date 02/10/18 Drawn BH Designed JG Checked AP Approved CRAIGERNE LANE BED LOWERED TO ACCOMMODATE WAVERLEY MILLS Client Approval XX15 LARGER CULVERT A - Approved XX16 B - Approved with Revisions C - Do Not Use

BUCHAN PLACE Purpose of Issue Status Suitable for Coordination S1 ANGLE PARK XX17

TWEEDBANK LEY XX18 Unit 2.1 ANGLE PARK Quantum Court Research Avenue South Heriot Watt University Edinburgh EH14 4AP United Kingdom

TRAQUAIR ROAD www.jbaconsulting.com XX19 UTR t +44 (0)131 3192940 f +44 (0)845 8627772 e [email protected]

SECTION A-A Offices at Coleshill, Doncaster, Edinburgh, Exeter, Glasgow, Haywards Heath, Isle of Man, Leeds, Limerick, 1:50 Newcastle upon Tyne, Newport, Peterborough, Saltaire, Skipton, Tadcaster, Thirsk, Wallingford and Warrington Project XX20 TWEEDBANK LEY Borders Flood Studies XX21

200 YEAR WATER LEVEL REPROFILED Title CHANNEL Innerleithen: Option 3 Chapman's Burn GEOMETRY 200 Year Culvert upgrade with improved channel conveyance

for Client

The property of this drawing and design vested in Jeremy Benn Associates Ltd. It shall not be reproduced in whole or in part, nor disclosed to a third party, without the prior written consent of Jeremy Benn Associates Ltd. This map is reproduced from Ordnance Survey material with the permission of the Ordnance Survey on behalf of the Drawn: A Coad 13/02/18 controller of Her Majesty's Stationery Office. Unauthorized reproduction infringes Crown Copyright and may lead to Scale prosecution or civil proceedings. © Crown copyright and database rights (2018) Ordnance Survey (100023423) Designed: J Garrett 12/02/18 As Shown @ A1 Checked: A Pettit 12/07/18 Approved: PLAN SECTION B-B Project Number: 2017s5526 1:2000 1:50 Drawing Number Revision AEM-JBAU-IL-CB-IM-C-1100 P02 OPTION SUMMARY. Option aims to acheive a 1 in 200 year DAMSIDE standard through the combination of upstream channel/culvert LEITHEN ROAD Innerleithen improvements, upgrading of existing FPS culverts from the culvert entrance to Hall Street, the creation of a flood storage

DAMSIDE area to minimise culvert upgrades in the downstream section.

CHURCH STREET LEITHEN WATER Option 4: Chapmans Burn Manholes would also need to be sealed. Option to open up upper section of the culvert.

B709 MAXWELL STREET CHAPEL STREET CHURCH STREET REPLACED HEADWALL TO BE LEVEL WITH TOP OF BANK 200 Year Storage with Channel

FILL 5m LONG LOW SPOT ON RAISE 10m LONG

RIGHT BANK UP TO 170.7m AOD ROAD LEITHEN LOW SPOT ON RIGHT A Reprofiling, Sealed Manholes BANK BY 0.45m NT32368901 B DROP CHANNEL BY 0.56m AT CULVERT FACE AND TIE BACK INTO EXISTING A CHANNEL LEVEL 10m UPSTREAM and New Upgraded Culvert Inlet_0000 B XXX1

UPGRADE CULVERT B709 CHAPEL STREET TO Ø825mm AND PEEBLES ROAD AS PART OF THIS OPTION THE CULVERT LOWER CULVERT BOND STREET INLET BY 0.87m TO COULD BE CONVERTED TO OPEN CHANNEL AS FAR AS THE NORTHERN END OF THE

ACCOMMODATE ROAD LEITHEN

LARGER CULVERT RESERVOIR HORSBRUGH TERRACE

LEITHEN WATER REPLACEMENT CULVERTS

HORSBRUGH STREET Manhole APPROX. 185m LONG GEORGE STREET Existing Culverts Proposed Culverts XXX3 A72 Sealed UPGRADED CULVERT Manhole SURCHARGING FROM CULVERT IS ID Number Diameter (mm) Diameter (mm)

MANHOLES SEALED AND COLLECTED BY OFF-LINE STORAGE B709 Inlet_0000 300 1200 No NON RETURN VALVES BRIDGEND FITTED TO INLETS FROM EMBANKMENT TIES INTO QUEEN STREET XXX1 300 900 No THIS MANHOLE DOWN TO EXISTING GROUND XXX5 XXX4 BUCCLEUCH STREET OUTLET WITH THE RIVER XXX3 450 900 No LEGEND

TWEED A72 STORAGE AREA WATER LEVEL CHAPEL STREET HORSBRUGH STREET 144.86m AOD XXX4 450 600 No EXISTING GROUND LEVEL

PRINCESS STREET LEITHEN CRESENT XXX5 450 600 Yes A72 FINISHED GROUND LEVEL XXX6 450 600 Yes 200 YEAR FLOOD LEVEL

XXX6 XXX7 600 600 Yes BUCCLEUCH STREET NEW CULVERT CONNECTION TO STORAGE AREA XXX8 600 600 Yes UPGRADED CULVERT XXX7 A72 LEITHEN WATER PRESSURE BUILD UP IN THE CULVERT IS XXX9 UTR 600 600 Yes XXX8 WAVERLEY ROAD RELEASED INTO THE STORAGE AREA, SEALED CULVERT PRINCESS STREET XX10 600 N/A Yes THE WATER IS STORED SAFELY UNTIL THERE IS CAPACITY IN THE CULVERT TO XX11 UTR 600 N/A Yes RAISED EMBANKMENT

RELEASE THEPEEBLES STORED ROAD WATER INTO THE XXX9 UTR RIVER TWEED XX12 UTR 600 N/A Yes CULVERT ALIGNMENT

LEITHEN CRESENT BUCCLEUCH STREET

MORNINGSIDE CHAMBERS STREET HALL STREET XX13 UTR 600 N/A Yes NEW STORAGE AREA

MAXIMUM ANTICIPATED DEPTH FOR WAVERLEY ROAD XX14 UTR 600 N/A Yes A72 200 YEAR FLOOD EVENT IS 1m MANHOLE / CULVERT INLET XX15 600 N/A Yes EXISTING WATERCOURSE XX16 600 N/A Yes XX10 PRINCESS STREET

ST RONAN'S TERRACE XX11 UTR XX17 600 N/A Yes LEITHEN CRESENT XX18 600 N/A Yes

WAVERLEY PLACE EXISTING CULVERT TO BE RETAINED LEITHEN WATER A72 XX12 UTR PRINCESS STREET XX19 UTR 675 N/A Yes AND 17 Nr MANHOLES TO BE SEALED AND INLETS FITTED WITH NON XX20 675 N/A Yes RETURN VALUES WHICH DRAINMILLER STREET INTO THIS CULVERT. XX21 675 N/A Yes

NT32368901 280 900 No XX13 UTR LEITHEN MILLS PRINCESS STREET Cha_0049BU 850 N/A No

TRAQUAIR ROAD

MILLER STREET WAVERLEY MILLS Comments Background mapping transparency reduced and manhole / culvert inlets altered XX14 UTR P02

COWFORD COURT Rev.: Date 02/10/18 Drawn BH Designed JG Checked AP Approved RIGHT BANK REPROFILED AND Client Approval RAISED BY 0.45m PEEBLES ROAD WAVERLEY MILLS CRAIGERNE LANE A - Approved WAVERLEY MILLS 200 YEAR WATER LEVEL XX15 B - Approved with Revisions BED LOWERED TO ACCOMMODATE C - Do Not Use XX16 LARGER CULVERT Purpose of Issue Status Suitable for Coordination S1

BUCHAN PLACE

ANGLE PARK XX17 Unit 2.1 Quantum Court TWEEDBANK LEY Research Avenue South XX18 Heriot Watt University ANGLE PARK Edinburgh EH14 4AP United Kingdom www.jbaconsulting.com t +44 (0)131 3192940

TRAQUAIR ROAD f +44 (0)845 8627772 e [email protected] XX19 UTR Offices at Coleshill, Doncaster, Edinburgh, Exeter, Glasgow, Haywards Heath, Isle of Man, Leeds, Limerick, Newcastle upon Tyne, Newport, Peterborough, Saltaire, Skipton, Tadcaster, Thirsk, Wallingford and Warrington

SECTION A-A Project 1:50 Borders Flood Studies

XX20TWEEDBANK LEY Title XX21 Innerleithen: Option 4 Chapman's Burn 200 Year SoP Storage with Channel Reprofiling, 200 YEAR WATER LEVEL REPROFILED CHANNEL Sealed Manholes and New Upgraded Culvert Plan GEOMETRY for Client

The property of this drawing and design vested in Jeremy Benn Associates Ltd. It shall not be reproduced in whole or in part, nor disclosed to a third party, without the prior written consent of Jeremy Benn Associates Ltd. Drawn: A Coad 13/02/18 LEITHEN WATER Scale Designed: J Garrett 12/02/18 This map is reproduced from Ordnance Survey material with the permission of the Ordnance Survey on behalf of the As Shown @ A1 controller of Her Majesty's Stationery Office. Unauthorized reproduction infringes Crown Copyright and may lead to Checked: A Pettit 12/07/18 prosecution or civil proceedings. © Crown copyright and database rights (2018) Ordnance Survey (100023423) Approved: Project Number: 2017s5526 PLAN SECTION B-B Drawing Number Revision AEM-JBAU-IL-CB-IM-C-1200 P02 1:2000 1:50 OPTION SUMMARY. Work to the open channel upstream of the culvert to increase conveyance of burn and culverts and

DAMSIDE Innerleithen alleviate flood risk to nearby houses.

CHURCH STREET LEITHEN WATER

B709 MAXWELL STREET CHAPEL STREET CHURCH STREET Option 5: Chapmans Burn REPLACED HEADWALL TO BE LEVEL WITH TOP OF BANK

FILL 5m LONG LOW SPOT ON UPGRADE CULVERT Improved Upstream Channel

RIGHT BANK UP TO 170.7m AOD TO Ø825mm ROAD LEITHEN A

SW DROP CHANNEL BY 0.56m AT CULVERT B SW SW SW FACE AND TIE BACK INTO EXISTING Conveyance CHANNEL LEVEL 10m UPSTREAM A SW

SW B SW SW

CHAPEL STREET B709

SW PEEBLES ROAD

SW FILL 10m LONG LOW SPOT ON BOND STREET RIGHT BANK UP BY 0.45m SW SW EXISTING CULVERT

SW ALIGNMENT ROAD LEITHEN

SW HORSBRUGH TERRACE

LEITHEN WATER

SW HORSBRUGH STREET

SW A72

SW B709

SW BRIDGEND

SW QUEEN STREET

SW BUCCLEUCH STREET

SW A72 CHAPEL STREET HORSBRUGH STREET

SW LEGEND

PRINCESS STREET

LEITHEN CRESENT

SW A72

SW EXISTING GROUND LEVEL

SW SW FINISHED GROUND LEVEL SW

SW BUCCLEUCH STREET

SW 200 YEAR FLOOD LEVEL

SW UPGRADED CULVERT

LEITHEN WATER SW A72

SW WAVERLEY ROAD RAISED EMBANKMENT SW

SW PRINCESS STREET SW

SW CULVERT ALIGNMENT

SW EXISTING WATERCOURSE PEEBLES ROAD

BUCCLEUCH STREET SW LEITHEN CRESENT MORNINGSIDE SW CHAMBERS STREET HALL STREET

WAVERLEY ROAD

SW A72

SW SW RIGHT BANK REPROFILED AND SW

SW PRINCESS STREET RAISED BY 0.45m

ST RONAN'S TERRACE SW

SW 200 YEAR WATER LEVEL

SW LEITHEN CRESENT BED LOWERED TO ACCOMMODATE

WAVERLEY PLACE

SW LARGER CULVERT LEITHEN WATER

A72 SW PRINCESS STREET

SW MILLER STREET

SW LEITHEN MILLS

TRAQUAIRSW ROAD

SW MILLER STREET SW WAVERLEY MILLS

SW Background mapping transparency reduced

COWFORD COURT Comments SW P02

SW WAVERLEY MILLS PEEBLES ROAD SW Rev.: Date 02/10/18 Drawn BH Designed JG Checked AP Approved SW SECTION A-A CRAIGERNE LANE

SW WAVERLEY MILLS SW 1:50 Client Approval

SW A - Approved

SW B - Approved with Revisions

SW C - Do Not Use

BUCHAN PLACE SW

SW Purpose of Issue Status

ANGLE PARK SW Suitable for Coordination S1

SW TWEEDBANK LEY

SW Unit 2.1 ANGLE PARK SW Quantum Court SW

SW Research Avenue South

SW Heriot Watt University

SW Edinburgh SW EH14 4AP SW United Kingdom SW TRAQUAIR ROAD SW www.jbaconsulting.com

SW t +44 (0)131 3192940

SW f +44 (0)845 8627772 SW e [email protected]

SW SW Offices at Coleshill, Doncaster, Edinburgh, Exeter, Glasgow, Haywards Heath, Isle of Man, Leeds, Limerick, SW

SW Newcastle upon Tyne, Newport, Peterborough, Saltaire, Skipton, Tadcaster, Thirsk, Wallingford and Warrington

SW Project

SW TWEEDBANK LEY

SW SW Borders Flood Studies SW

SW SW Title SW SW 200 YEAR WATER LEVEL REPROFILED Innerleithen: Option 5 Chapman's Burn SW SW CHANNEL SW Improved upstream channel conveyance SW GEOMETRY SW

SW for SW Client SW

EXISTING CULVERT SW

OUTFALL SW

SW LEITHEN WATER The property of this drawing and design vested in Jeremy Benn Associates Ltd. It shall not be reproduced in whole or in part, SW nor disclosed to a third party, without the prior written consent of Jeremy Benn Associates Ltd. SW RIVER TWEED This map is reproduced from Ordnance Survey material with the permission of the Ordnance Survey on behalf of the Drawn: A Coad 13/02/18 controller of Her Majesty's Stationery Office. Unauthorized reproduction infringes Crown Copyright and may lead to Scale prosecution or civil proceedings. © Crown copyright and database rights (2018) Ordnance Survey (100023423) Designed: J Garrett 12/02/18 As Shown @ A1 Checked: A Pettit 13/02/18 Approved: PLAN SECTION B-B Project Number: 2017s5526 1:2000 1:50 Drawing Number Revision AEM-JBAU-IL-CB-IM-C-1300 P02 Preferred Option for Innerleithen

Summary of short listed options

Option Properties Environmental Working Constraints/ limitations Mitigating residual Improved public Best use (Standard of protected implications with natural risks awareness of public Preferred Options and protection) processes money 1) Property Level 47 of 48 No impact Natural flood Intrusive into people’s homes, will require All properties protected with Option should be presented BCR 3.4 recommendations Protection (PLP) - management reinstallation every 25 years. PLP will also be protected to public for comment. Leithen Water opportunities Some flood damages are associated with under the 200 year climate Signage relating to flooding (0.5% AP - 200 have been each flood event, as well as clean up cost. change event, additional and sand bag stores should If taken forward and selected by year) identified and Roads and gardens are not protected. properties will require PLP as be erected. Ensure could be the 200 year climate change Innerleithen residents are SEPA’s Prioritisation process then the incorporated flood extent is larger. aware of the Resilient within the Community Programme preferred option for the Leithen scheme to 2) Direct Defences 48 of 48 Minimal direct provided In order to avoid excess wall lengths only This option will not protect BCR 4.3 – Leithen Water impact additional properties who are anticipated to suffer properties from flood events in Test reliability of flood Water is Option 2 - Direct Defences flood damages above floor level have been excess of the 200 year event. warning system and consider (0.5% AP - 200 environmental targeted for protection. The minimum Designing to the 200 year plus improving it by installing an year) benefits. With an in channel debris screen required wall length is 450 m with a wall climate change event is additional gauge further up height of between 450mm to 900mm. requires a wall length of the catchment upstream of the A72 Road Bridge. Gardens and low level damage to homes approximately 800 to 1000m will still be experienced by several and would require raising of the properties A72 Road Bridge to avoid wall This could be implemented alongside heights in excess of 2.5 m. natural flood management. The short term recommendations for the Chapman’s Burn is:

1) Property Level 24 of 31 No impact No suitable Intrusive into people’s homes, will require All properties protected with Installation of a flow gauge BCR 4.3 Protection (PLP) - additional NFM reinstallation every 25 years. PLP will also be protected on the Chapman’s Burn for • Improved channel conveyance Chapman’s Burn measures Some flood damages are associated with under the 200 year climate flood warning, calibration and (0.5% AP - 200 each flood event, as well as clean-up cost. change event, additional flow estimates. • Flow gauging for improved flow year) Roads and gardens are not protected. properties will require PLP as the 200 year climate change flood extent is larger. estimates

3) Culvert Upgrade 31 of 31 Replacement of culverts shall be disruptive Channel and culvert could be BCR 0.7 • Telemetry on FPS screen – Chapman’s Burn to the community for access and noise. made larger now to accommodate further increase in flows.

4) Offline Storage – 31 of 31 A portion of the Offline storage embankment peak height is Channel, storage culvert could BCR 1.3 In the long term, depending on the Chapman’s Burn existing culvert approximately 1.3m at street level so be made larger now to (0.5% AP - 200 could be replaced should not be too much of a visual impact. accommodate further increase collected gauge data, a flood year) with an open The offline storage is utilising an existing in flows. channel instead of a playing field, the playing field is to be larger culvert maintained but will require some protection scheme should be redevelopment. 5) Channel 3 of 28 No impact Effect of flood water after upgrade needs to Channel could be made larger BCR 32 progressed for Chapman’s Burn Upgrade – be assessed in greater detail now to accommodate further Chapman’s Burn increase in flows. (50% AP - 2 year) What can we do in terms of natural flood management?

Location and type of What is natural flood management? suggested measures for the Natural flood management (NFM) is when natural processes are used Leithen Water catchment to reduce the risk of flooding by slowing flows and storing water within the catchment. It is however difficult to quantify the reduction in flow that these types of measures can deliver. NFM also offers additional wider benefits by restoring habitats and improving water quality. NFM opportunities were first identified by examination of aerial photography and was confirmed with a site visit at sample locations. The NFM measures which have been proposed for the Leithen Water include: • Improved and management practices • Working within the banks (buffer strips, debris dams) • Woodland planting • Wetland creation and leaky barriers The Council will need to investigate the potential benefits before working with other parties on developing these options further.

Typical example of Typical example of in- Typical example of wetland creation channel debris barrier young woodland What happens next?

The following sets out the Council wide steps required to progress preferred options to a Flood Protection Scheme

Option appraisal and first SBC Council review and Selected Flood round of public decision to enact Protection Schemes consultation preferred options taken forward to outline • October 2018 • January 2019 design stage • 18 months

Schemes prioritised for Further consultation on Issue proposed and 2021 FRM cycle outline design selected schemes to SEPA for prioritisation • December 2019

Scheme approval by Carry out detailed design Produce tender Council, stakeholders of flood protection documents and procure and public measures contractor