45 6. Flood Risk to Planned Development 6.1 Introduction In line with development targets set by the regional plans and in line with the Council’s Local Development Scheme (LDS), Pendle Borough Council is currently considering allocations of land for future development. As outlined in Section 2, there are plans for regeneration and redevelopment of brownfield sites in urban areas throughout the Borough, and there may be a need for future growth in adjacent greenfield areas. The key areas of development are planned in Nelson, Brierfield and Colne based on areas of housing market decline identified for strengthening by the HMR Pathfinder programme (see Box 2.1). Most future development will be focused on the urban areas. Flood risk is an important consideration in guiding the location of new development in the Borough, highlighted by previous flood incidents that have caused the inundation of properties, some of which have been repeatedly affected. The key objective of this SFRA is to assess flood risk throughout the Borough, focussing in particular on areas at risk and where development is planned, to ensure informed planning decisions that reduce flood risk. In terms of assessing these areas, the emerging PPS 25 is the key policy driver. The PPS 25 Sequential Test provides a rigorous process for assessing and prioritising the location of planned development with respect to flood risk. It is primarily based on the Environment Agency’s flood zones defined by the probability of flooding from rivers and the sea, but also requires other sources of flooding to be considered, together with potential future flood risks (such as changes in land use or climate) and residual flood risks. The overriding aim of the Sequential Test is to steer all new development to the lowest flood risk zone (i.e. zone 1). Where this is not possible, depending on its vulnerability, development may be permitted in the higher risk flood zones if the criteria of the Exception Test are met (see Section 4.2.2). This section provides an assessment of the potential areas in the Borough in which development may occur in line with the objectives of the PPS 25 Sequential Test, with a view to informing planning decisions on the location of future development. The local flood risks identified in each area can then guide more detailed FRAs of sites selected for development. 6.2 Potential Development Areas Currently the areas which are likely to be the subject of future or re- development in Pendle Borough are based on the HMR Pathfinder programme (see Box 2.1) and are shown in Figure 2.1. Figures 6.1 to 6.3 show the areas in more detail for Nelson, Brierfield and Colne respectively. The following sections comprise an assessment of the local flood risks affecting each site. h:\projects\hm-250\18108 pendle sfra\docs\stage 2 report\rr057i3.doc © Entec UK Limited 30 October 2006 46 6.2.1 South Valley AAP South Valley AAP is a 154 hectare area situated approximately 4 kilometres northeast of Nelson Town Centre (see Figure 6.3 and Plate 6.1). The existing urban area of Colne forms the northern boundary, with Carry Bridge and Primet Bridge to the east and west respectively. To the south, land slopes up towards Deerstone Moor. The areas covers existing residential development, industry in the lower area of the site adjacent to Colne Water (Lenches), and a large area of predominantly open fields used for pasture, hedgerows and some wooded areas along the watercourses. Detailed proposals for the regeneration of the area are not yet available, though may involve some new development in the valley bottom along with environmental improvements to the existing landscape and townscape across the remainder of the area. Colne Water flows in a westerly direction through the site. Church Clough Brook and a number of other minor tributaries of Colne Water also flow through the southern part of the site in a northerly direction to Colne Water. Potential flood risks to consider with respect to the redevelopment of the South Valley site include: • Fluvial flooding from Colne Water. Figure 6.3 shows that parts of the site lie in the medium and high risk flood zones 2 and 3; • Fluvial flooding from Church Clough Brook and other minor tributaries of Colne Water. The Environment Agency has not derived flood zones for these small watercourses. Further investigations to assess the extent of the associated flood risks will be required; • Blockages and/ or insufficient capacity of any existing bridges/ culverts and/ or any new crossings proposed in association with new development; • Sewer flooding due to capacity exceedance, backing up or blockages of existing and/ or new surface water networks proposed in association with new development; • Overland flow from upslope fields to the south and urban areas to the north; • Possible groundwater flooding associated with springs near the heads of the minor tributaries. 6.2.2 Bradley AAP The Bradley AAP site is a 32 hectare area situated just to the north of Nelson Town Centre (see Figure 6.1). Currently the area mostly comprises terraced housing together with two large mill complexes; Throstle Nest Mill and the now derelict site of the former Riverside Mill. Currently the proposals to regenerate the area includes the clearing of some areas for new build housing and open space, while other areas have been identified for possible environmental improvements or facelift. Walverden Water passes through the site including through the grounds of Riverside Mill (see Plate 6.2). It is culverted under part of the mill site, and from the mill to the Bradley AAP boundary. The NFCDD indicates capacities of 1 in 25 to 50 years for the Walverden Water culverts. Hendon Brook is also culverted under the site and joins the culverted Walverden Water on site. h:\projects\hm-250\18108 pendle sfra\docs\stage 2 report\rr057i3.doc © Entec UK Limited 30 October 2006 47 Plate 6.1 View of South Valley from Kiln Hill, looking north down towards Colne Plate 6.2 Riverside Mill, looking southeast from Charles Street Walverden Water flows in from the right behind the remains of the steel framed building, and then flows from the chimney stack towards the brick wall where it enters the culvert under Charles Street. h:\projects\hm-250\18108 pendle sfra\docs\stage 2 report\rr057i3.doc © Entec UK Limited 30 October 2006 48 Potential flood risks to consider with respect to the redevelopment of the Bradley site include: • Fluvial flooding from Walverden Water. Figure 6.1 shows that parts of the site lie in the medium and high risk flood zones 2 and 3; • Fluvial flooding from Hendon Brook. The Environment Agency has not derived flood zones for this small watercourse. Further investigations to assess the extent of the associated flood risks will be required; • Blockages and/ or insufficient capacity of the culverted sections of Walverden Water and Hendon Brook; • Sewer flooding due to capacity exceedance, backing up or blockages of the surface water network serving the area; • Overland flow from surrounding urban areas. 6.2.3 Brierfield Railway Street AAP The Brierfield Railway Street AAP is a 10 hectare area situated approximately 2.5 kilometres south of Nelson Town Centre (see Plate 6.3 and Figure 6.2). The Colne-Burnley Railway forms the western boundary, and the A682 the eastern boundary. Currently the area mostly comprises terraced housing, several shops and places of worship. Detailed proposals for the regeneration of these areas are not yet available, though they may include a mixture of clearance for new build housing and open space, facelifting, group repair and associated environmental improvements. The Sefton Street COW and Hollin Mill COW (both now enmained) are culverted through the south and north of the site respectively. Potential flood risks to consider with respect to the redevelopment of the Brierfield Railway Street site include: • Fluvial flooding from the Sefton Street and Hollin Mill COWs. The Environment Agency has not derived flood zones for these small watercourses. Further investigations to assess the extent of the associated flood risks will be required; • Blockages and/ or insufficient capacity of the culverted Sefton Street and Hollin Mill COWs; • Sewer flooding due to capacity exceedance, backing up or blockages of the surface water network serving the area; • Overland flow from surrounding urban areas. 6.2.4 Churchfields, Colne PAA Churchfields PAA is a 1.4 hectare area situated just west of Colne Town Centre (see Figure 6.3). Currently the area is predominantly terraced houses. Redevelopment proposals include group repair and garden extensions with some demolition to allow for a small housing development and a community garden. The North Valley Stream is culverted just to the north of the Churchfields area. h:\projects\hm-250\18108 pendle sfra\docs\stage 2 report\rr057i3.doc © Entec UK Limited 30 October 2006 49 Plate 6.3 View of the Railway Street Corridor Looking south down Cross Street, across Railway Street and up Sackville Street. The Sefton Street COW follows Montague Street, passes underneath Sackville Street, before passing down under Holden Street Mill (and the Brierfield Canal Corridor) and under the canal towards Pendle Water. Potential flood risks to consider with respect to the redevelopment of the Churchfields site include: • Fluvial flooding in the northern edge of the site from the North Valley Stream. The Environment Agency has not derived flood zones for this small watercourse. Further investigations to assess the extent of the associated flood risks will be required; • Blockages and/ or insufficient capacity of the culverted North Valley Stream; • Sewer flooding due to capacity exceedance, backing up or blockages of the surface water network serving the area; • Overland flow from surrounding urban areas.