Flood Risk Assessment

Project

Proposed Replacement Dwelling

Garside Street / Shelley Street | Worksop | Nottinghamshire |

S81 7BH

Tel: 01909 591871 E. [email protected] E. [email protected] www.yorkearchitecture.com M. 07828 789 651 M. 07929 456 125

Contents

0.0 Introduction 1.0 Development and Site Location 2.0 Sequential and Exceptions Test Statement 3.0 Definition of Flood Hazard 4.0 The Probability of Flooding 5.0 Climate Change Effect 6.0 Flood Risk Measures 7.0 Off Site Impacts 8.0 Residual Risks

Appendices

Appendix A – Site Location

Appendix B – Site Plan

Appendix C – Site Levels

Appendix D – Environment Agency and SFRA Information

Appendix E – Wastewater and Drains Map

Appendix F – Evacuation Plan

Appendix G – Glossary of Terms

1.0 Introduction

The assessment has been undertaken in accordance with the National Planning Policy Framework (NPPF). It uses information of the existing topography, existing surface water drainage systems, historical flood records and simulated flood maps.

This Flood Risk Assessment has been prepared in support for a proposed development of a 1No replacement dwelling located / accessed from Garside Street, Worksop, S80 2DD.

Relevant information was sought from the Environment Agency (EA) and the local flood authority (Nottinghamshire County Council). Possible sources of flooding will be evaluated to determine the risk they pose to the development site. The effect of climate change will also be considered, and any off-site impacts caused, by the development.

Should the risk of flooding prove to be significant, the report will endeavour to minimise the impact on the development and the local area throughout its design life to protect against the threat to life. In summary, this report confirms the proposal can be developed safely, with negligible impact on flood risk off-site.

In summary the finished floor level (FFL) of the proposed dwelling is to be a minimum of 30.96mAOD to protect the dwelling against flooding. Two bedrooms will be located on the first floor to provide a safe refuge for the occupants should evacuation not prove achievable, although evacuation from the development site is a quick and easy affair given the proximity to the flood zone 2/3.

Any dwelling within 8m of the top bank of the River Ryton will require permission from the Environment Agency.

2.0. Development and Site Location

2.1 Site Location The site is in the township of Worksop, 0.70km southeast of the city centre. Worksop is the principal town in the Bassetlaw district, lying on the River Ryton at the northern edge of the Sherwood Forest. The site is bordered by residential dwellings with Priorswell Recreational Ground along its east and southern borders. There is a large Morrison’s supermarket 120m north, which is part of a large commercial/services park. Grid reference E459450, N379107. Refer to Appendix A for the site location.

The nearest main watercourse, the River Ryton that runs adjacent to the sites southern border. The Chesterfield Canal runs a similar course to the River Ryton on its northern bank through Worksop. The canal passes over the River Ryton around 640m to the east where it continues to follow the river on its south bank for a distance before diverging at Ranby,

6.15km northeast. The site sits in between the River Ryton and the Chesterfield Canal as they flow east out of Worksop.

2.2 Site Description The proposed development is to demolish Rose Cottage and erect a new dwelling in approximately the same location. The new dwelling will benefit from the same large garden as the original. A rough site plan is attached in Appendix B. The gross site area is approximately 0.15Ha. The site ranges from 30.12 to 30.80 metres Above Ordnance Datum (mAOD). The topography is relatively level across the site, with a gentle gradient slope southeast towards the River Ryton. The site levels are provided by UK Map Centre, available in Appendix C. From BGS data the bedrock geology is noted as Lenton sandstone formation – sandstone with the potential for Alluvium superficial deposits - clay, silt, sand and gravel. Nearby BGS borehole data also indicates this and indicates the potential presence of groundwater at 3.00m below ground.

2.3 Classification of Vulnerability Table 2 of the Technical guidance to the NPPF, the classification of the proposed development is in the ‘More Vulnerable’ category.

2.4 Flood Zone Classification The Environment Agency’s flood map shows that the development site is located within a Flood Zone 2. This zone comprises land assessed as having between a 1 in 100 and 1 in 1,000 annual probability of river flooding (1% – 0.1%), or between a 1 in 200 and 1 in 1,000 annual probability of sea flooding (0.5% – 0.1%) in any year. (Appendix D).

2.5 Local Development Plan The Bassetlaw Local Development Plan (BLDP) is intended to address the district’s housing and economic needs, taking into consideration other social and environmental policies, by 2037. The BLDP calls for 9087 homes by 2037, by making best use of available land. The local plan covers the whole of Bassetlaw (Figure 1). Paragraphs 3.23, 3.24 of the BLDP identify and need for additional housing in the district to meet the issues for an expanding population. Also identified is the regeneration and renewal that an increase in housing has spearheaded, acting as a catalyst for investment. By increasing housing in the district, it is the hope to attract new industry and national chains.

Figure 1 - Bassetlaw District

Worksop, where the development site is located is planned to grow in a sustainable manner, with new roads and infrastructure. It is an area where infill housing developments are actively encouraged, as the towns principal district. Paragraph 5.1.16 of the BLDP identifies Worksop as the most sustainable location for significant growth and the best location to deliver the goals of the spatial strategy. Worksop is a priority development site, due to its ability to expand. Worksop will deliver some 2180 new dwellings over the plan period. The other major towns for renewal are Retford and Harworth, although the approach to renewal is different to that of Worksop. Policy ST1 actively encourages the use of greenfield sites to bring change about as part of the spatial strategy. Although the development site is greenfield it is

infill and does not increase the urban footprint. The settlement can be seen in Figure 2 below.

Figure 2 - BLDP Settlement Hierarchy

3.0 Sequential and Exceptions Test

In accordance with the Department for Environment, Food and Rural Affairs and the Environment Agency’s published guidance on the sequential and exceptions tests (developments that don’t need a sequential test)

‘You don’t need to do a sequential test if one has already been carried out for a development of the type you’re planning (eg a residential development) for your site’

A sequential test has already been carried out for this site on a previous application, however, more importantly, this is an application for a replacement dwelling and as such there is no increase in dwelling numbers and no increase in flood risk or the number of households at risk from flooding.

4.0 Definition of the Flood Hazard

The sources of flooding that could potentially affect the site are the following: -

• Flooding from water courses o River Ryton o Chesterfield Canal o Chesterfield Canal Feeder o Sandhill Lake • Flooding from land • Flooding from sewers • Flooding from ground water • Flooding from reservoirs

A Main River Map is attached in Appendix D.

4.1 The River Ryton

In the case of the River Ryton it is considered that fluvial flooding represents the worst- case scenario rather than tidal flooding, and therefore fluvial flooding is considered over tidal flooding.

The development sites south border abuts the north bank of the River Ryton. The EA information includes modelled water level results for various defended storm events of the River Ryton. Table 1 below details a summary of the information most relevant to the site. Refer to Appendix D for EA data. The EA have not provided any floodplain heights or crest levels for this model.

Table 1; - Defended modelled results of the River Ryton at the points closest to the site.

From table 1 the levels for a 0.1% (1 in 1000 year event) from the relevant node points is 30.36mAOD. With a minimum finished floor level (FFL) of 30.96mAOD, 600mm above the 1 in 1000 year event, adequate protection against flooding is provided for the lifetime of the development. The 30.96mAOD FFL is 730mm above the predicted flood level for a 1 in 100 year event, with climate change taken into consideration.

The Bassetlaw District Council 100 year with climate change flood depth (Appendix D) predicts the southern half of the site would be the worst affected, inundated with water to a maximum depth of 0.5m in such an event. Interpolating the flood depth against the ground levels from the UK Map Centre data (Appendix C), the flood depth is 30.80mAOD. The minimum FFL of 30.96mAOD is 160mm above the 1 in 100 year +CC event SFRA scenario.

A source of flooding is identified as overtopping Priorswell Road that flows into Shelley Street during a 1 in 100 year storm event (Appendix D). This is confirmed in the Bassetlaw council Dynamic Map which shows the flow moving along Shelley Street from Priorswell Road (Appendix D). For a 1 in 100 year flood event the indicated flood heights are only 0.08m. Also identified is the possibility of bank overtopping, but only as far as the gardens to the rear of those on Shelley Street.

The Bassetlaw District council Hazard Map identifies the southern part of the site is ‘Danger for most’. This

‘Danger for most’ area or zone is the same area identified as being flooded to a depth of 0.5m by the Bassetlaw flood depth map. Coincidentally, interpolating the EA modelled flood levels with the ground levels, this area is indicated to flood in a 1 in 100 year +CC storm event. The rest of the site is graded as danger for some and very low hazard moving north away from the River Ryton.

The proposed FFL of 30.96mAOD is circa 300mm above the existing ground levels to the north and around 760mm to the south, therefore providing a significant level of protection against flooding.

The risk to the dwelling is therefore considered to be medium to low.

4.2 Chesterfield Canal

The Chesterfield Canal is situated approximately 120m north of the development site. It is owned, operated and managed by the Canal and River Trust. The water level in the canal is controlled and maintained to allow navigation.

During extreme storm events it is possible the canal may overtop, although this is unlikely. Large amounts of water entering the canal would cause the water levels to rise between lock gates and there is a small possibility of the lock gates then being overtopped, especially if sluices become blocked. Canals have mechanisms in place to control the water level between lock gates, and rising water levels tend to spread themselves over the length of the canals. As such, they are much less prone to changing water levels.

The Bassetlaw SFRA states that canals do not generally pose a direct flood risk as a regulated waterbody. However, there is a residual risk and the SFRA calls for an analysis of these potential risks.

Overtopping is the more likely to occur than a breach, although ultimately is still unlikely occurrence. If water entering the canal caused overtopping the flood water would first meet the rear gardens and houses on Garside Street. As the gradient is shallow the flood water would move slowly around the dwellings. If the flood water were to make it around the houses on the north side of the Garside Street, then the water would enter the road channel. It is likely at this point that much of the water would be conveyed along the road channel to the east/southeast. If the water managed to surpass the road and flow further south, then it would meet the dwellings on the south side of the street. Again, this provides a barrier against the flow of water and the velocity at this point would be very low. Should the floodwater manage to overcome these obstacles then it would be spreading out at low velocities. At the point it met the development site would not have the required depth or speed to pose much risk to the site.

There have been historic incidences of breach and overtopping in the Bassetlaw District. Canals that follow natural contours can act as conduits for flood waters and carry floodwater from one area to another. In 2009 specific canal breaches were mapped in Worksop and Retford (Figure 3).

Figure 3 – Worksop Canal Breach

From the breach analysis pictured in figure 3, the water could reach the site with a maximum potential depth of up to 0.5m. If the flood water were to achieve this maximum depth then the maximum interpolated flood depth at the northern border of the site is 30.76mAOD + 0.5m = 31.26mAOD, 300mm above the recommended site FFL.

Due to the addition of bedrooms at first floor level the occupants are safe in the event of a breach. From Table 1 below, the hazard level is ‘danger for some’, with a floodplain height of around 100mm, and a distance from the site of approximately 120m.

Table 1 – The Defra R&D Technical Report FD2320/TR2 – Table 12.2

It is considered extremely unlikely that the breach will occur, with no formal defences that could fail as the canal is cut into the ground with the crest almost at the same level as the ground adjacent to it. Given there is no habitable accommodation to be at ground level and that the development employs flood risk measures it is considered that the development is safe for its lifetime and the risk of flooding from the canal very low.

4.3 Chesterfield Canal Feeder

The Chesterfield Canal Feeder is around 70m away to the south if the River Ryton. A feeder canal is a canal that carries water to a larger main canal. The site is not considered at risk from flooding from the feeder canal as it is extremely unlikely to cause flooding much like the Chesterfield Canal is not considered a risk. Furthermore, flood water from the feeder canal, however unlikely to occur, would be intercepted by the River Ryton.

The risk of flooding to the site is very low from the feeder canal.

4.4 Sandhill Lake

Sandhill Lake is a small fishing lake 0.95km north west of the site. There are no recorded instances of flooding arising from the lake and it is not identified as a risk of flooding in

the EA flood maps (Appendix D). The site is not considered at risk of flooding from the lake.

4.5 Flooding from Land

Surface water (pluvial) flooding is defined as flooding caused by rainfall-generated overland flow before the runoff enters a watercourse or sewer. In such events, sewerage and drainage systems and surface watercourses may be entirely overwhelmed. Pluvial flooding will usually be the result of extreme rainfall events, though may also occur when lesser amounts of rain falls on land which has a low permeability and/or is already saturated, frozen or developed. In such cases overland flow and ‘ponding’ in topographical depressions may occur.

The topography naturally indicates a general decline towards the River Ryton which is an even gradient on both banks. The river follows the overall decline from west to east. The Surface water flooding is likely to be contained within the highways and channelled into the local sewer network. Some overland flows may flow towards and enter the river.

The site has a gentle decline towards the south, towards the River Ryton, from 30.80mAOD at the north of the site to the river circa 30.12mAOD. Flood water will naturally flow towards the River Ryton, away from the site. The EAs surface water flood risk map indicates there is some risk to surface water flooding in a 1 in 100 year storm event (Appendix D).

Low Risk (0.1%(1 in 1000yr) - 1%(1 in 100yr) chance of flooding): - The depth is noted to between 300mm and 900mm with a potential velocity greater than 0.25m/s. The maximum interpolated flood water level would be around 31.29mAOD at the centre of the site if the extent of flood water is as shown.

Medium Risk (1%(1 in 100yr) – 3.3%(1 in 30yr) chance of flooding): - The depth is noted to be <300mm with a potential velocity greater than 0.25m/s. The maximum interpolated flood water level would be around 30.59mAOD at the centre of the site if the extent of flood water is as shown.

High Risk (greater than 3.3%(1 in 30yr) chance of flooding): - No flooding noted.

In respect to the low risk scenario, the probability that surface water flooding would reach the indicated height is very low. Once site levels are fixed at 30.96mAOD it is likely surface water would flow away from the site to the lower lying land of the Priorswell Recreational Ground.

From local knowledge it is known that Garside Street flooded during the 2007 floods, meaning Garside Street may be prone to flooding. The flood water was carried along Garside Street east to lower elevations and flooding is reported to have occurred east of Garside Street where the River Ryton and Chesterfield Canal cross. This is the beginning of a natural flood plain.

At present there is a medium risk during an extreme storm event of flooding from surface water on the site at current given site levels. Post development the risk of surface water flooding to the site would be low.

4.6 Flooding from Sewers

There is a 375mm diameter combined gravity/lateral drain running from west to east through the centre of the site, from Shelley Street. The drain connects with a 1125mm and 500mm combined gravity/lateral drains that runs south to north under the River Ryton. The connection point is around 7m east under Priorswell Recreational Ground and a larger 1275mm combined carries the wastewater away. The combined drain heads east/southeast. The invert depth of the connection point is 3.2m below ground or 27.28mAOD.

A 100mm foul water gravity/lateral drain servicing the houses of Shelley Street runs under houses of both sides of the street. Both drains combine into the previously mentioned combined drain.

A little further away, there is a 300mm combined sewer and a 225mm surface water sewer running under Garside Street from west to east. 150mm foul water sewers service the dwellings along Garside Street and connect into the combined sewer. The combined sewer continues along Garside Street while the surface water drain connects to a larger 600mm surface water drain that heads south empties into the River Ryton, circa 100m east of the site.

The mains and services maps and associated documentation can be seen in Appendix F.

Should any blockages occur or suffer from exceedance of the sewers flood water would follow the road channel. It is unlikely that such water would encroach onto the site from Garside Street due to the relative distances between the road channel and the site. Should the same occur on Shelley Street the flood water would likely follow the road channel or eventually flow south towards the River Ryton. The recommended minimum FFL would result in flood water from passing around the dwellings.

There is some history of sewer flooding in the surrounding area, the closest being on Garside Street (Appendix D). There is a medium risk of flooding from sewers, although at 30.96mAOD FFL the risk posed to the site itself is low.

4.7 Flooding from Ground Water

Groundwater flooding is the emergence of water from beneath the ground, either at a specific point or at different locations. The effect is usually local and does not usually pose a significant risk to life. Groundwater flooding can, however, cause significant property damage and lead to ground instability.

There are several factors that can lead to groundwater flooding including prolonged rainfall, high in bank river levels, artificial structures, groundwater rebound and mine water rebound. Developments that are in areas susceptible to groundwater will not always be suited to SuDS, dependent on a detailed site investigation and risk assessment.

According to the Bassetlaw SFRA the site is in an area of >25%<50% susceptibility to groundwater flooding. The SFRA groundwater susceptibility is only an indicator of where water might emerge, not the chance that it will emerge. There are no known records of ground water flooding in the vicinity of the site. The risk of groundwater flooding is considered low.

4.8 Flooding from Reservoirs

The EA have mapped the potential area for flooding should any flooding occur originating from reservoirs. The flood maps simulating such an occurrence are available in Appendix D. Should such an event occur the water is modelled to be below 0.3m with a velocity less than 0.5m/s, hence the risk to the site is very low. Moreover, flooding occurring from reservoirs is a rare occurrence due to the level of inspection and maintenance required under the Reservoir Act 1975.

5.0 The Probability of Flooding

5.1 Probability of Flooding

According to the Environment Agency the site is located within Flood Zone 2: land assessed as having between a 1 in 100 and 1 in 1,000 annual probability of river flooding (1% – 0.1%), or between a 1 in 200 and 1 in 1,000 annual probability of sea flooding (0.5% – 0.1%) in any year (land shown in lighter blue on the Flood Map). Refer to Appendix D.

It is considered that the River Ryton poses a medium risk of flooding to the site. The section of the River Ryton immediate to the site does not have any active flood defences, other than the embankment leading to the rear gardens of the dwellings on Shelley Street. The potential source of flooding identified is flood water overtopping the banks at Priorswell Road and overland flows towards the site down Shelley Street from drainage exceedance. The site would be 120mm clear should the flood water reach the maximum indicated height of 30.84mAOD at any point of the site. The nearest node point to the site indicates flood water would reach 30.36mAOD, giving 600mm freeboard. It is considered that the minimum FFL of 30.96mAOD mitigates the flood risk to the development site.

It is considered unlikely that overtopping of the Chesterfield Canal would occur as any additional water would be managed by the overtopping of the lock gates, dissipating flood waters further downstream before overtopping the banks. In the event that overtopping should occur flood water would spread at low velocities. Surface water ponding may occur in the vicinity of the site for a short period and is not seen to be a significant risk to the development. Flood water originating from the feeder to the Chesterfield Canal is a similarly low risk. In both cases flood water would likely be retained within the road channels.

Based on previous recorded sewer flooding to a maximum depth of 300mm it is considered there is a low to medium risk of flooding at present.

The site is not considered to be at significant risk of flooding from other local watercourses or from ground water emergence.

5.2 Surface and Foul Water Discharge

Rose Cottage is currently on the north part of the site and is a serviced building. There is a combined sewer running from west to east through the site in line with Shelley Street. There are foul sewers running from the dwellings on Shelley Street into the combined sewer. The combined sewer connects to other combined sewers to the west of the site under Priorswell Recreation Ground which flow away to the east/southeast. There are several combined and surface water drains in the nearby roads, please consult Appendix F for location, flow direction and depths.

It is recommended that for any proposed site, surface water discharge from the site be via soakaways and other infiltration systems where possible. However, a detailed ground investigation and percolation testing will be required to determine the suitability of any infiltration systems. It is noted that water has been struck at 3m below ground but boreholes are recommended to confirm this as data is not recent or immediately close by. Soakaways must be designed in accordance with British Research Establishment (BRE Digest 365) or another recognised method.

Should infiltration structures not be possible then surface water should be attenuated on site and a discharge rate agreed with either the Environment Agency or the Nottinghamshire County Council Drainage Board as required to allow surface water

discharge into a water course. Should this not be viable a connection to the public sewer may be permitted by the local water authority, however, consultation is advised.

Any foul water would be expected to discharge into the nearest public sewer, reported to running under Shelley Road and the site itself. The depth of the foul water pipe is 2.35m – 3.02m. The location can be seen in the Severn Trent Mains and Sewer Map (Appendix F). A gravity system to the point of connection should be viable.

6.0 Climate Change Effect

National Planning Policy Framework (Technical Guidance) (NPPF-TG) Table 5 suggests that a 20% increase in peak river flows will result from climate change in the period to 2115. The design model data provided is up to a 1 in 200 year event which estimates flooding to 2190, thus takes into account climate change beyond the required 2115 period.

The rise in water levels represents a marginally increased risk of the occurrence of a breach or overtopping. Such an event would likely to take place at the Priorswell Road and the rear gardens of Shelley Street, as identified by 100 year Physical Features Map.

A breach does not represent much risk in respect to flooding of the site. The embankments on the river Ryton maintained and constantly improved by the Environment Agency. The breach scenario on the River Ryton in the SFRA does not encroach onto the development site (Appendix D). A breach from the Chesterfield Canal is extremely unlikely with a low hazard rating. Danger is mitigated by prohibiting bedrooms at ground floor level.

The Chesterfield Canal is actively managed by balancing water levels between lock gates, and as such, are only affected by climate change via overland flow entering the locks. Lock gates have inbuilt maximum water level control mechanisms and should such mechanisms fail then lock gates overflow through the gate itself rather than the banks. Should overtopping still manage to occur the depth and velocity of water will cause little risk to the development site.

NPPF-TG suggests that a 30% increase in rainfall intensity will result from climate change in the period to 2115. Levels should be fixed so surfaces fall away from buildings or dwellings and any temporary surface water ponding does not pose a risk of flooding adjacent to the other nearby buildings. It is likely the Lead Local Flood Team, Environment Agency, Local IDB and the Water Authority will continue to monitor the surface water, drainage networks and rivers to mitigate any surface water flooding that may occur as a result.

7.0 Flood Risk Measures

The proposed development is deemed to be in the ‘More Vulnerable’ category of NPPF Table 2. Therefore, flood resilient construction in the lower parts of any permanent buildings should be considered where appropriate, in accordance with the document “Improving the Flood Performance of New Buildings – Flood Resilient Construction” (ISBN 9781 85946 2874).

Such measures may include:-

a) All services to be routed in the ceiling void and brought down walls to terminate at least 0.6m above floor level. b) Water sensitive apparatus such as boilers, water heaters and their controllers, to be mounted at least 1.2m above ground floor level. c) Ground floor construction to be solid concrete slab with floor insulation to be water resistant. d) Wall insulation to be of a closed cell water resistant material up to at least 900mm above ground floor level. e) If brickwork is proposed, then up to at least 0.9m above ground floor level should be of a low porosity (e.g. engineering brick) in order to minimise water absorption. f) Where possible chipboard and Medium Density Fibreboard should be avoided within 900mm of ground floor level. g) Openings in walls are to be minimised below 900mm above floor level. h) The building should be registered on the Environment Agency’s Flood Warning scheme. i) The finished floor level (FFL) of the proposed dwellings is to be a minimum of 30.96mAOD. j) All bedrooms to be located at 1st floor only to ensure the safety of the occupants.

The above minimum floor level will ensure that flood risk at the site arising from the identified sources of flooding is minimized during the lifetime of the building.

8.0 Off Site Impacts

8.1 Increase of Flood Risk Elsewhere

The development proposal will not increase the impermeable area of the site. Correctly designed there will likely be a decrease in surface water run-off, although, as this proposal is for a single replacement dwelling, it is likely that the potential for wider off site improvement will be negligible. As is currently the case, diverted flood water would likely flow into the adjacent empty field and back towards the River Ryton.

As the site is a very small area the change of storage from the dwelling will be insignificant and will have no overall effect on the flood levels within the flood zone 2, should such an extreme event occur to the indicated extent.

8.2 Management of Remaining Risks Over the Lifetime of the Development

Infiltration structures should be used wherever possible. Should infiltration structures not be viable then surface water should be attenuated on site on site and a discharge rate agreed with either the Environmental Agency, Canal and Rivers Trust or Nottinghamshire County Council Internal Drainage Board as required to allow surface water discharge into a water course.

Given that a watercourse is within economical distance of the development, discharge to the surface water sewer would most likely not be required. The peak rate will be required to be agreed with the local water authority, but consultation is advised to confirm this. Such consideration will serve to reduce the impact of the development upon the local area.

Any new surface water sewers and attenuation storage could to be offered for adoption by Severn Trent. Thereby the drainage system will be maintained over the life of the development by a statutory authority. Should the system be within the site boundary it will likely remain in private ownership, placing the onus on the owner of the dwellings to maintain the system for the life of the development.

9.0 Residual Risks

9.1 Remaining Flood Risks After Implementation of Protection Measures

It is inevitable that rare and extreme rainfall events will involve volumes of water that exceed the design standard of the surface water drainage which will lead to temporary surface ponding around the site. The final site levels of the proposed dwelling will be fixed so that in extreme conditions surface water flows away from them towards low lying landscaping. This will ensure to reduce the flood risk to the development during extreme rainfall events.

In an extreme event it is possible that the River Ryton may overtop. Should such an event occur then the topography indicates flow would be back towards the River Ryton, thus directing flood water away from the site. The Chesterfield Canal is considered a very low risk to the site.

It is proposed to raise the floor levels to 30.96mAODm. Combined with flood resilient construction the residual risk will be managed for the lifetime of the development. It is proposed that all bedrooms are at first floor height only to ensure the safety of the occupants. The first-floor level will also provide a place of safe refuge, should occupants not be able to leave the property in time from receiving a flood warning.

Access and egress to higher ground for the proposed development will be immediately north onto Garside Street which is outside of the flood zone 2/3 area. As Garside Street has been known to flood due to the sewer flooding it is advised to head north along Kilton Road towards Kilton. Safety is also available at first floor level in the unlikely event evacuation is not possible.

9.2 Management of Remaining Risks Over the Lifetime of the Development

The residual risk should be managed by the designers and the construction team for the development, who should ensure that its design and construction incorporate the points and recommendations contained within this assessment.

The development should be registered for automated flood warnings from the Environment Agency as soon as the development is in use.

A copy of the flood evacuation will be provided to all occupants on the site. Refer to Appendix F.

Appendix A – Site Location

Appendix B – Site Plan

Appendix C – Site Levels