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Home , Barrowford, Colne Water, Pendle Water, River Brun, Trawden, Trawden Brook

Burnley Nelson and Flood Risk Management Strategy

Flood Risk Reach 1

Flood Risk Reach 2 Cotton Tree

Flood Risk Reach 3 Colne

Flood Risk Reach 4 Lower Colne

Flood Risk Reach 5 North Valley Stream

Flood Risk Reach 6 Swindon Clough

Flood Risk Reach 7

Flood Risk Reach 8 Nelson College, Barrowford

Flood Risk Reach 9 Lomeshaye

Flood Risk Reach 10 Nelson Central

Flood Risk Reach 11 Fulledge,

Flood Risk Reach 12 Plumbe Street, Burnley

Flood Risk Reach 13 Burnley Central

Flood Risk Reach 14

Flood Risk Reach 15 Burnley East

Flood Risk Reach 16 Green Brook Upper

Flood Risk Reach 17 Green Brook Lower

Burnley Nelson and Colne Flood Risk Management Strategy

Flood Risk Reach 1: Trawden

Throughout the last ten years, flooding to properties has occurred twice in Trawden village, in 2000 and in 2001. This flooding occurred as a result of high flows and blockages in the brook. Today, 79 properties are at risk of flooding in the village with a 1% (1 in 100) chance of occurrence in any one year. 64 of these properties are at risk from more frequent events. Flooding in Trawden is caused by water coming out of the channel when levels are too high. This is made worse when the channel becomes blocked by debris at bridge crossings.

Rainfall can flow very quickly through the catchment, which means there is a limited amount of time in which to warn people of flooding. Whilst there is currently no flood warning service in place for Trawden we are looking at the possibility of providing this service. This would mean residents in the village have enough time to be warned and to act prior to a flood.

New flood defence walls, constructed along the left bank (looking downstream) of the river, could provide protection against a 1.33% chance flood event in any one year. We also propose to enhance our maintenance activities and consult with other parties to see what can be done to reduce the risk of blockage from existing river crossings. Flood resilience/resistance measures could also be considered to individual properties.

Burnley Nelson and Colne Flood Risk Management Strategy

Flood Risk Reach 2: Cotton Tree

Cotton Tree is a small settlement at the confluence of and , situated a short distance upstream of Colne. Flooding was recorded here in 1947, and although we have no record of flooding in the area since then, there are 77 properties at risk from a 1% (1 in 100) flood, with 31 of these having a 2% chance of flooding. Flooding is caused by overtopping of the river channel from an event with a 4% chance of occurrence in any one year.

Development in the area is mostly set back from the watercourse, behind the B6250 (Cotton Tree Lane), although immediately upstream of the confluence with Trawden Brook there are some properties close to the banks of Colne Water.

A flood defence embankment in the park, upstream of Winewall Bridge, could reduce the chance of overland flows from Colne Water into Cotton Tree. Gaps in riverside walls, south of Cotton Tree Lane would also need to be filled. The alignment and location of this embankment is to be determined but it could be positioned so as to utilise the existing park area to store water during very high river levels. However more investigation is required to promote this scheme and the work would be dependent on funding.

Key

Location where new defences or wall improvements may be required.

Wall improvements

New embankment

Burnley Nelson and Colne Flood Risk Management Strategy

Flood Risk Reach 3: Colne

The Colne flood risk reach sits alongside Colne Water, which flows in a westerly direction through the South Valley area. Development in Colne is spread across the whole valley and there are a number of former textile mills situated alongside the river that are now mainly occupied by industrial units. Raised walls are in place along the banks of Colne Water, however they contain gaps so would not stop river flows coming out of the channel.

Much of the flood risk reach is covered by the South Valley Area Action Plan (AAP), being produced by to regenerate the area. 13 commercial properties in this area are affected during a flood that has a 1% (1 in 100) chance of occurring. There is no residential property identified at risk of flooding on our published flood map. As the current standard of protection is reasonably high, we propose to continue our existing inspection, maintenance and enforcement activities.

Rainfall can flow very quickly through the catchment, which means there is a limited amount of time in which to warn people of flooding in Colne. Whilst there is currently no flood warning service in place we are looking at the possibility of providing this service. This would allow residents enough time to be warned and to act prior to a flood. The area is planned for redevelopment and developers will need to demonstrate to the Environment Agency how they propose to mitigate future flood risk.

Burnley Nelson and Colne Flood Risk Management Strategy

Flood Risk Reach 4: Lower Colne

Lower Colne is situated alongside Colne Water, downstream of Primet Bridge and the railway crossing. Although the river begins to meander here, more so than further upstream, it is constrained by the proximity of former mill buildings which form much of the river channel sides. There are no formal flood defences in Colne.

There are four major crossings, over the river in this location, and they all have significantly large openings so are unlikely to block flows. Many of the larger mill buildings have been divided into smaller properties, as a result, 70 commercial properties are at risk of a flood with a 1% (1 in 100) chance of occurring in any year. There are no residential properties identified at risk of flooding on our published flood map. As the standard of protection is reasonably high we are proposing to continue our existing inspection, maintenance and enforcement activities in Lower Colne.

Burnley Nelson and Colne Flood Risk Management Strategy

Flood Risk Reach 5: North Valley Stream

North Valley Stream runs to the north of the major urban area of Colne. 2km in length, it runs mainly underground through culverts and flows in open channels for the last 500m, before it joins Colne Water. The area adjacent to North Valley Stream is heavily developed with several large commercial properties directly over the culverted watercourse.

North Valley Stream is relatively steep causing it to be very ‘flashy’ i.e. where flood levels can rise and fall rapidly with little or no warning time. The river is contained within several culverts of varying size and condition, and flooding could occur if these sections should block, collapse or spill out due to lack of capacity. In this situation flow could escape through manholes or back-up within pipes carrying surface water or wastewater that discharges into North Valley Stream. When the culvert is at full capacity, surface water will be unable to discharge into North Valley Stream possibly leading to flooding of low lying areas.

18 properties, 5 of which are residential, are at risk from a 1% (1 in 100) chance of flooding in any one year but flooding could occur with more frequent events (from a 10% probability). This would become even more frequent if culvert conditions deteriorated as it would ultimately lead to it becoming blocked.

Due to the nature and potential scale of flooding here, a flood defence scheme would be high in cost and could cause significant disruption to the area. At the moment we are focusing on opportunities to reduce the risk from the culverted sections, particularly in relation to new developments. Through the planning process our Development & Flood Risk team will take actions to ensure that the probability and consequences of flooding are reduced.

Approximate line of culvert

Burnley Nelson and Colne Flood Risk Management Strategy

Flood Risk Reach 6: Swinden Clough

Swinden Clough is a minor watercourse that flows northwards from Gib Clough Head and joins Colne Water downstream of Colne. The watercourse enters into culverts as it passes under the Whitewalls Industrial Estate and emerges downstream where it flows through an open channel to join Colne Water.

Development along this reach is industrial/commercial and sits immediately above the line of the culverted watercourse. There are a number of large modern industrial units and associated storage and parking sites too. There are 3 commercial properties are at risk from flooding.

The culvert itself does not pose a significant risk. Our river modelling indicates it can manage flows with a 0.5% (1 in 200) chance of occurring in any one year. However, without continued maintenance, the potential for a blockage is high. There are no records of flooding in Swinden Clough although the local authority has reportedly prevented flooding in recent years by removing debris build up at the culvert entrance.

The preferred option for this area is to provide debris screens at the entrance to the culverts to support the existing inspection and maintenance works. We will seek contributions from beneficiaries to implement these works. Key:

Location of potential new debris screens

Approximate line of culvert

Burnley Nelson and Colne Flood Risk Management Strategy

Flood Risk Reach 7: Barrowford

Barrowford is situated to the north of Nelson on the A682 and sits where and Colne Water join. The Barrowford flood risk reach covers the area adjacent to, upstream of the confluence on Pendle Water. Pendle Water flows southwards from through the centre of the village on the right bank and the historic Park Hill on the left bank.

Records show that flooding did occur in this area in 1967, when the bridge at Wilton Street was washed away. The walls adjacent to the A682, Rd, do provide a flood defence protecting Barrowford from a 0.5% (1 in 200) chance of flooding in any one year.

In Barrowford we propose to continue our inspections and monitoring of the channel deposits, and to undertake maintenance and enforcement action where necessary. This could include removing vegetation from sediment, and shoal build-ups if it restricts flows in the channel and leas to flooding problems in the future.

Burnley Nelson and Colne Flood Risk Management Strategy

Flood Risk Reach 8: Nelson College, Barrowford

The Nelson College flood risk reach is immediately downstream of the Barrowford flood risk reach and mostly includes residential properties. A flood alleviation scheme which included the construction of new flood walls and embankments, was completed here in 2006. Previously, the area had a long history of flooding, with the most recent event recorded in 2000.

The flood defences provide protection from a 1.33% (1 in 75 ) annual probability of a flood, from Pendle Water to over 650 properties in Barrowford. There are also over 660 properties covered by a flood warning service in this area.

We propose to continue our inspections in this area, monitoring the channel deposits and undertaking periodic maintenance and enforcement where necessary. This could include removing vegetation from sediment, and shoal build-ups if it restricts flows in the channel and leas to flooding problems in the future.

Key:

Area at risk of flooding but benefiting from defences constructed by the Environment Agency

Burnley Nelson and Colne Flood Risk Management Strategy

Flood Risk Reach 9: Lomeshaye

The Lomeshaye flood risk reach is downstream of Barrowford and Nelson College and is characterised by modern industrial units constructed on both sides of Pendle Water (which flows in a south westerly direction through this reach). There are also a number of residential properties close to older mill buildings. A flood alleviation scheme was completed along the industrial estate in 2000 providing protection against a 1.33% (1 in 75) chance of flooding in any one year.

There is a long history of flooding in this area with the most recent recorded event in 2000. There are over 186 properties covered by a flood warning service in this area.

We propose to continue with our inspection and maintenance works at this location. If the defences continue to be maintained, they will provide a standard of protection for a flood event with a 1% chance of occurring in any year.

Key:

Area at risk of flooding but benefiting from defences constructed by the Environment Agency

Burnley Nelson and Colne Flood Risk Management Strategy

Flood Risk Reach 10: Nelson Central

Walverden Water sits high up in the catchment. It flows 3.4km through a steep sided valley from Walverden Reservoir, through the town of Nelson in , to its confluence with Pendle Water. Hendon Brook is a tributary of Walverden Water and has a small, steep catchment.

The watercourses are heavily engineered with culverts and walls dating from the Victorian era. Walverden Water is culverted for 1.6km and Hendon Brook for 1.2km; approximately 50% of their total lengths. There is a long history of flooding in this area with the most recent recorded event in 2000. The culverts along both watercourses have been in a poor structural condition and are prone to blockage from the build up of debris.

We have investigated the level of flood risk in detail and we are in the process of constructing a scheme to reduce this risk. The first phase of the scheme, focussing on Hendon Brook, was completed in 2008. Works on Walverden Water are scheduled to be completed in 2011.

The scheme comprises of a number of different engineering elements, which includes hydraulic improvements and remedial works along each watercourse. The improvements will increase the existing standard of protection for Walverden Water from 10% (1 in 10) to a 1% (1 in 100) chance of a flood occurring each year. For Hendon Brook the existing 10% standard of protection has been increased to provide protection against an event with a 1.33% (1 in 75) chance of occurring in each year.

Pendle Water

Hendon Brook

Walverden Water

Key Open Channel

Culverted Channel

Burnley Nelson and Colne Flood Risk Management Strategy

Flood Risk Reach 11: Fulledge, Burnley

Fulledge is a suburb of Burnley situated to the southeast of the town centre. Development in Fulledge consists mainly of terraced housing with some light industrial units. A new school, Unity College, has been constructed on the right bank of the River Calder to replace the existing Towneley High School currently situated on the opposite bank, further downstream.

The majority of houses are set back from the river, which allows some protection from the wide area of low lying, undeveloped floodplain provided by Towneley Park. However, nearly 150 properties are at risk from a flood with a 1% (1 in 100) chance of occurring in any one year. Over 30 of these properties are at risk from a 4% (1 in 25) annual flood. There are no formal flood defences in this area although the raised walls and embankments provide some flood protection during high river flows.

The area is covered by a flood warning system and provides approximately 2 hours warning to an area covering 885 properties.

New flood defence embankments with ramped footpaths along the edge of the recreation ground could provide protection during a 1.33% (1 in 75 year) annual flood, to 143 residential properties. Use of the old Towneley High School site, on the left bank (looking downstream), could also be sufficient to store some excess flood flows. Funding will be sought to promote this scheme but will be dependent on its priority against other schemes across the country.

Key: Location where new defences or wall improvements may be required.

Area highlighted for potential flood storage.

Burnley Nelson and Colne Flood Risk Management Strategy

Flood Risk Reach 12: Plumbe Street, Burnley

Plumbe Street is an urban area near the centre of Burnley directly upstream and to the east of the and Liverpool Canal. Development in Plumbe Street is situated on both sides of the watercourse and is a mixture of residential properties and industrial units, the latter mainly being former textile mills.

There are no formal flood defences in this area although there are many building sides and boundary walls that act as flood defences. Flooding could occur in the area during a 1.33% (1 in 75 year) event but property would not be affected until a more extreme event occurred. There are over 185 properties covered by a flood warning service in this area.

We propose to continue our inspection and maintenance works at this location. If our inspections indicate that there are particular problems within the culvert or other structures, we would undertake repairs to maintain the standard of protection.

Burnley Nelson and Colne Flood Risk Management Strategy

Flood Risk Reach 13: Burnley Central

The Burnley Central flood risk reach covers the majority of the town centre of Burnley from the Leeds Liverpool canal down to where the Calder and Brun meet. The Brun joins the Calder from the east, as the Calder flows northwards through the town. Sections of this river are very steep and in some places in a very deep channel.

There are numerous raised walls and buildings that form the channel sides through Burnley which make it very difficult to inspect and maintain the channel. They are not formal defences but do provide some level of protection.

There are several culverted sections of watercourse along both rivers. The longest section of culvert is the Charter Walk Culvert (300m long) on the , which is constructed under the shopping centre and access roads. Three other culverts pass under buildings and local roads, but are significantly shorter than the Charter Walk Culvert. The remaining culverts all pass under roads. St James road bridge would be most likely to block if left unmaintained.

This area is generally protected to a 0.5% standard of protection (1 in 200 chance of occurring in any one year) because the restricted culvert size under the canal holds back high river flows. However, 22 properties upstream of St James road bridge are affected by a 2% (1 in 50) chance of occurrence and 11 of these by more frequent flooding. There are over 185 properties covered by the Burnley Town Centre flood warning service.

We propose to continue our inspection and maintenance works at this location. If our inspections identify particular problems within the culvert or other structures we would look to undertake repairs to maintain the standard of protection.

Burnley Nelson and Colne Flood Risk Management Strategy

Flood Risk Reach 14: Padiham

Development in the centre of Padiham is spread across both sides of the River Calder and a number of properties back immediately onto the watercourse. Flood risk is mainly located on the north side and right bank of the river where development is predominantly commercial.

95 properties are affected by flooding with between a 4% and 1.33% probability in any one year (1 in 25 to a 1 in 75 chance of occurrence). There are no formal flood defences in the town but flood protection is provided by walls running behind the council offices and river banks upstream along the playing fields. There are 141 properties covered by a flood warning service in the town.

New flood defence walls and embankments could provide protection against at least a 1.33% flood (1 in 75 chance of occurrence). Whilst this scheme is economically viable it must be considered against other scheme across the country. Contributions from developers and existing businesses affected would enable us to promote this scheme. With sufficient contributions, there would be an opportunity to deliver wetland habitat in the area.

Key:

Location where flood defence improvements may be required.

Burnley Nelson and Colne Flood Risk Management Strategy

Flood Risk Reach 15: Burnley East

The Burnley East flood risk reach covers the area at risk of flooding from the River Brun to the east of Burnley town centre. Development in the area is confined to the lower parts of the reach with small areas of dense housing on the left and right bank and some commercial properties. The largest development in the area is the former Burnley College of Arts, which is set on the inside of a meander on the left bank of the Brun.

Upstream of the college, through , the River Brun has a relatively natural channel. However, around the College of Arts the watercourse has been contained within a deep, walled channel with masonry sides and a stone bed. There are no formal flood defences in this area. There are numerous raised walls, but due to the depth of the channel the sections above ground level do not act as flood defences.

Flooding could occur of this channel overtops in Thompson Park. The low lying park area fills with flood water which then spills over and flows overland through the Burnley College site. None of the bridges along this reach restrict high flows. The Burnley College site is at risk from flood events with a 4% (1 in 25) chance of occurring in any given year.

The College site is due for redevelopment, therefore we do not propose to undertake any works. The developer will undertake an appropriate flood risk assessment as part of the planning process. We will continue with our current inspection, maintenance and enforcement works in the Burnley East area.

Burnley Nelson and Colne Flood Risk Management Strategy

Flood Risk Reach 16: Green Brook Upper

Green Brook is a minor tributary of the River Calder on the southern outskirts of the town of Padiham. The area comprises mainly new residential development but it also includes a number of properties that existed beforehand. Another small watercourse, a tributary of Green Brook called Sweet Clough, sits within this reach.

There are no formal raised flood defences but garden walls form channel sides in most locations. As a result there are very few access points into the channel to undertake inspections and repairs. There are five road crossings which, if left to block with debris, would lead to flooding. Assuming these constrictions do not block, the majority of houses are not at risk from a 1.33% annual probability flood (1 in 75 chance of occurrence). There are 239 properties covered by a flood warning service in this location.

We propose to continue our inspection and maintenance works at this location. If our inspections indicate that there are particular problems within the river channel, we would undertake repairs to ensure the standard of protection is maintained.

Burnley Nelson and Colne Flood Risk Management Strategy

Flood Risk Reach 17: Green Brook Lower

In its lower reach Green Brook passes through the southern portion of Padiham which is heavily developed. Development is now predominantly residential although there remain a number of large industrial units, the sites of former textile mills.

57 properties are at risk from a flood with a 1% (1 in 100) chance of occurring each year. Flooding from the river begins at a 10% probability flood (1 in 10 chance of occurrence) but the flood depth is so low that most properties would not flood until a 1.33% (1 in 75 chance) event.

The area at highest risk is the Palmerston Street area, on the right hand bank of the channel. Just upstream of this location the Shakespeare Street road bridge constricts flow and water can back up and overtop the channel walls flowing overland into a wide flat area occupied by residential properties. There are 239 properties covered by a flood warning service in this location.

We have considered maintenance to reduce blockages of the channel and two options to raise the standard of protection (raised walls and an upstream storage pond). As the cost to raise the standard of protection is greater than the total cost of the flood damage, our preferred option is to continue with our inspection and maintenance works at this location. If our inspections indicate that there are particular problems within the river channel, we would undertake repairs to maintain the standard of protection. We may also promote flood resilience/resistance measures to individual properties.