Flood Risk Assessment

Consulng Civil, Structural & Geo‐Environmental Engineers

Site Address:

Residenal Development at Burnley Road Bacup

Paul Waite Associates Ltd Summit House Riparian Way The Crossing Report Ref: 13019/I/01 Cross Hills March 2013 BD20 7BW [email protected] www.pwaite.co.uk Report No.13019/I/01 Project Details. FRA – Residential Development at Burnley Road, Bacup Date. March 13

Flood Risk Assessment

Paul Waite Associates have been appointed by the RTB Partnership, to undertake a Flood Risk Assessment in support of a planning application for residential development on land located off Burnley Road in Bacup, Lancashire.

Clients Details

RTB Partnership

Documents Revision Status

ISSUE: DATE COMMENTS ‐ March 25, 2013 FINAL

Report No.13019/I/01 Project Details. FRA – Residential Development at Burnley Road, Bacup Date. March 13

Contents

Executive Summary 1

1.0 Introduction 4

2.0 Approach to the Flood Risk Assessment 5

2.1 Approach 5

2.2 Application of the Sequential and Exceptions Test 5

3.0 Site Details 7

3.1 Location 7

3.2 Former/Current Use 7

3.3 Proposals 8

3.4 Boundaries 8

3.5 Topography 9

3.6 Existing Drainage 10

3.7 History of Flooding 10

3.7.1 British Hydrological Society – Hydrological Events 10

3.7.2 Internet Search for Historical Flooding 10

3.7.3 Irwell Catchment Flood Management Plan (December 2009) 10

3.7.4 Rossendale Borough Council Level 1 SFRA (2008) 11

3.7.4 Lancashire PFRA (2011) 12

4.0 Flooding Mechanisms 14

4.1 Fluvial: River Irwell 14

4.1.1 Modelled Flood Level Data 15

4.1.2 Overtopping: 1 in 100 year Event 15

4.1.3 Overtopping: 1 in 100 year + Climate Change Event 15

4.1.4 Overtopping: Extreme 1 in 1000 year Event 16

4.1.5 Danger to People from Overtopping 17

4.1.6 Infrastructure Failure: Blockage or Structural Failure & Overland Flow 18

4.2 Fluvial: Unnamed Watercourse 20 Report No.13019/I/01 Project Details. FRA – Residential Development at Burnley Road, Bacup Date. March 13

4.2.1 Estimation of Flows within the Unnamed Watercourse 22

4.2.2 Capacity of the Upstream Channel 23

4.2.3 Capacity of Culverted Watercourse 24

4.2.4 Hydraulic Failure 28

4.2.6 Conclusion 31

4.3 Surface Water Runoff 31

4.3.1 Existing Drainage Regime 31

4.3.2 Existing Greenfield Runoff Rates 32

4.3.3 Proposed Drainage Regime 33

4.3.4 Sustainable Urban Drainage Systems (SUDS) 36

4.3.5 Residual Flood Risk 40

4.4 Groundwater 40

4.5 Overland Flow 40

4.6 Infrastructure Failure: Reservoirs 40

4.7 Ponding 40

5.0 Material Consideration In Respect of the National Planning Policy Framework 42

5.1 Climate Change 42

5.2 Environment Agency Flood Map 42

5.3 Finished Floor Levels 43

5.4 Emergency Access and Egress during Times of Flood 43

5.5 Flood Warning 43

5.6 Evacuation Plan 44

5.7 Culvert Diversion/Easement 45

5.8 Preliminary Drainage Strategy 45

5.8.1 General 45

5.8.2 Attenuation Requirement 46

5.8.3 Maintenance 46

5.8.4 Layout 46

5.9 Foul Drainage 47 Report No.13019/I/01 Project Details. FRA – Residential Development at Burnley Road, Bacup Date. March 13

6.0 Conclusions and Recommendations 48

Tables

Table 1 Flood Risk Vulnerability and Flood Zone Compatibility Table 2 Sources of Flooding Table 3 Environment Agency Modelled Flood Levels for the River Irwell at Bacup Table 4 Dangers to People from Overtopping Relative to Distance from Defence Table 5 Existing Greenfield Runoff Rates (Site Area = 0.52Ha) Table 6 SUDS Planner Results Table 7 Indicative Attenuation Details

Figures

Figure 1 Location Plan – Existing Development at Burley Road, Bacup Figure 2 Historical Map of the Development Site (Circa 1893) Figure 3 Existing Site Viewed South West along Burnley Road Figure 4 Summary of Significant Historic Floods in Lancashire Figure 5 Past Flood Event Locations (Lancashire) Figure 6 River Irwell Viewed Upstream from the Culvert Headwall at Cooper Street Figure 7 Anticipated Flood Conveyance Route South along Burnley Road Figure 8 River Irwell Viewed Upstream from the Culvert Headwall at Cooper Street Figure 9 Approximate Route of Culverted Watercourse Figure 10 Confluence of the Unnamed Watercourse with the River Irwell Figure 11 Sketch Illustrating Route of Unnamed Watercourse Upstream of the Site Figure 12 Estimated Catchment Area – Unnamed Watercourse Figure 13 Typical Cross Section through Open Channel Section of Unnamed Watercourse

Figure 14 Type 1 & Type 5 Culvert Flow Figure 15 Culvert Inlet under Type 1 Free Flow Conditions Figure 16 Culvert Inlet with 50% Blockage Figure 17 Possible Hydraulic Failure Modes Figure 18 Areas Susceptible to Groundwater Flooding (2011) Report No. 13019/I/01 Project Details FRA – Residential Development at Burnley Road, Bacup Date. March 13

Figure 19 Environment Agency Flood Map Figure 20 Environment Agency Flood Warning Coverage Map

Appendices

Appendix A Existing Site: Topographical Survey Appendix B Proposed Development Plan Appendix C Environment Agency Flood Level Data Appendix D IOH124 River Flow Calculation Appendix E IOH124 Existing Greenfield Runoff Appendix F Historic Borehole Logs & Soilscape Map Appendix G SUDS Planner Appendix H Catchment Area Plan Appendix I Attenuation Calculations – Outfall 1 Appendix J Attenuation Calculations – Outfall 2 Appendix K Attenuation Calculations – Outfall 3 Appendix L Preliminary Drainage Layout

Report No. 13019/I/01 Project Details FRA – Residential Development at Burnley Road, Bacup Date. March 13

Executive Summary

Paul Waite Associates have been appointed to undertake a Flood Risk Assessment in accordance with the National Planning Policy Framework (2012), to support a planning application for a proposed residential development located off Burnley Road in Bacup, Lancashire.

The development covers a gross area of 0.52Ha; and is currently undeveloped. The site is shown to lie predominantly within Flood Zone 1 of the Environment Agency Flood Map; which is defined as land assessed as having a less than 1 in 1000 annual probability (<0.1%) of river or sea flooding within any year.

However it is noted that the eastern boundary of the site is situated within Flood Zone 3 of the Environment Agency Flood Map, which is defined as the zone having a 1 in 100 year or greater annual probability of flooding (>1%) or a 1 in 200 year or greater annual probability of flooding from the sea (>0.5%) in any year.

The primary sources of flood risk to the proposed development are identified from the River Irwell, which is culverted as it flows southwards along the route of Burley Road near the site; an unnamed tributary of the River Irwell which flows in culvert along the south boundary of the site; overland flow from elevated agricultural land situated immediately to the west; and an increase to surface water runoff and volume following development.

The Environment Agency has provided modelled flood level data for the open channel sections of the River Irwell, immediately upstream and downstream of the existing culvert.

Undertaking a comparison of flood levels against existing road levels indicates that overtopping is likely to occur only during the extreme 1 in 1000 year flood event. However due to the limited information provided; and the poor condition of the channel walls upstream from the development; overtopping may occur during the more frequent flood events. This concurs with historical flood incidents within this area of Bacup.

During such an event; although the development site is elevated above potential flooding emanating directly from the River Irwell; it is noted that Burnley Road forms a conveyance channel, whereby flood water can flow southwards towards Bacup town centre.

The depth of flooding at the proposed site access is estimated to be 0.23 metres.

In conclusion, the River Irwell presents a low risk of fluvial flooding within the development area of the site; however the risk increases to medium to high at the site access.

To mitigate against this flood risk, it is recommended that residents are advised to sign up to receive flood warnings via the Environment Agency’s Free Flood Warnings Direct Service; and devise an evacuation plan, to enable safe escape from the site if required to do so.

Report No. 13019/I/01 Project Details FRA – Residential Development at Burnley Road, Bacup Date. March 13

It is further recommended that the Developer provides a suitable pedestrian route westwards away from Burnley Road, which can link in to established footpaths, directing residents towards Ash Street/Dale Street and into the town centre, along routes which are located outside of the flood plain.

An unnamed tributary of the River Irwell is culverted along the south boundary of the application site via a 525mm diameter culvert. The exact route and structural condition of the culvert are unknown at this time.

Evaluation of the culvert and upstream channel indicates that under normal flood conditions, both exhibit sufficient capacity to contain the 1 in 100 year plus 20% climate change flow.

Hydraulic failure within culverted watercourses may occur when flows exceed the design capacity of the structure; or blockage; sedimentation; or structural failure occurs.

In the event that the culvert barrel becomes blocked by up to 50% of its cross sectional area; calculations indicate that the headwater level will be elevated to such an extent that overtopping at the culvert inlet or headwall is likely to occur.

Due to the topography surrounding the development; flood water is likely to be directed downhill, overland across the site towards Burnley Road.

It is recommended that a CCTV/Trace survey is undertaken to map the route of the existing culvert through the site. If the route of the culvert needs to be diverted to accommodate the development; although the watercourse is riparian owned, proposed plans will need to be approved by the Local Authority.

Furthermore in order to ensure that the culvert maintains free flow throughout its length, it is recommended that inspection and maintenance is undertaken at regular intervals.

In the event that the culvert inlet is overtopped; it is recommended that a formal conveyance route is engineered into the proposed development; to steer flows across the site thereby reducing the risk of inundation of the properties via sheet flow.

Open agricultural land is located at an elevated position to the west of the proposed development. During extreme rainfall, where the ground is saturated, surface water is likely to flow overland, downhill towards Burnley Road.

In order to minimise the risk of flooding within the site caused by this mechanism, it is recommended that a field drainage system is constructed along the west boundary of the site. This drainage system may be discharged to the culverted watercourse.

Following development it is anticipated that the impermeable area within the site will be increased from 0Ha to an area approximating 66%, or 0.344Ha; hence there will be a corresponding increase in surface water runoff and volumes leaving the site.

Report No. 13019/I/01 Project Details FRA – Residential Development at Burnley Road, Bacup Date. March 13

The existing site is undeveloped; and as such, post development runoff must be maintained at greenfield runoff rates. Flows in excess of this will need to be attenuated within the site, prior to discharge.

Undertaking an assessment for disposal of surface water using the hierarchy outlined within Approved Document H of the Building regulations (2002) concludes that infiltration methods are liable to be unsuitable for this development.

As such it is proposed that surface water will discharge to the culverted watercourse located along the south boundary of the site.

The Environment Agency requires that surface water runoff should be controlled as near to its source as possible, through a sustainable drainage approach to surface water management (SUDs).

This approach involves using a range of techniques such as soakaways and swales to reduce flood risk by attenuating the rate and quantity of surface water runoff from a site.

Undertaking an assessment of suitable SUDs techniques indicates online/offline storage; green roof; and permeable paving solutions; along with rainwater harvesting are the most appropriate source control techniques for this development.

Rainwater harvesting may be implemented in order to assist in reducing the surface water runoff volume to pre‐development values.

The Preliminary Drainage Strategy incorporates 3No outfalls to the culverted watercourse; in order to minimise the depth of the pipework over the steeply sloping site.

Using MicroDrainage Source Control the initial design of the attenuation structures is:  Outfall 1: 51.4m of 0.8m(H) x 1.2m (W) box culvert, with 41mm diameter orifice flow control.  Outfall 2: 54.1m of 0.8m(H) x 1.5m (W) box culvert, with 44mm diameter orifice flow control.  Outfall 3: 39.8m of 0.8m(H) x 1.2m (W) box culvert, with 42mm diameter orifice flow control.

It is recommended that the calculations are revisited during the detailed design phase to accommodate the final development layout; contributing areas; existing and proposed runoff rates; and requirements imposed by the Environment Agency; Rossendale Council; and United Utilities.

Report No. 13019/I/01 Project Details FRA – Residential Development at Burnley Road, Bacup Date. March 13

1.0 Introduction

Paul Waite Associates have been appointed to undertake a Flood Risk Assessment in support of a planning application for a proposed residential development located on land off Burnley Road in Bacup, Lancashire.

The development covers an area approximating 0.52 Hectares and is shown to lie predominantly within Flood Zone 1 of the Environment Agency Flood Map; which is defined as land assessed as having a less than 1 in 1000 annual probability (<0.1%) of river or sea flooding within any year.

It is highlighted however that the eastern boundary of the site is situated within Flood Zone 3 of the Environment Agency Flood Map, which is defined the zone having a 1 in 100 year or greater annual probability of flooding (>1%) or a 1 in 200 year or greater annual probability of flooding from the sea (>0.5%) in any year.

The primary source of flood risk to the proposed development site has been identified as the River Irwell, however, other sources of flooding have been considered within this assessment.

It is usual for the Environment Agency to raise an objection to development applications within the functional floodplain or Zone 2 or 3 of the flood map until the question of flood risk has been properly evaluated. The Agency will also object to developments where the total site area is in excess of 1 Hectare until suitable consideration has been given to surface water runoff.

Report No. 13019/I/01 Project Details FRA – Residential Development at Burnley Road, Bacup Date. March 13

2.0 Approach to the Flood Risk Assessment

2.1 Approach

A topographical survey of the existing site was undertaken by Tricad Solutions in January 2013 and calibrated to Ordinance Datum. As such, the levels provided by the topographical survey have been utilised within this report.

The requirements for flood risk assessments are generally as set out in the ‘Technical Guidance to the National Planning Policy Framework’, published in March 2012; and in more detail from the Environment Agency’s ‘Standing Advice on Flood Risk’ available from http://www.environment‐agency.gov.uk/reasearch/planning/82584.aspx.

2.2 Application of the Sequential and Exceptions Test

The risk based sequential test should be applied at all stages of planning. Its aim is to steer new development to areas at the lowest probability of flooding, within Zone 1. The flood zones are the starting point for the sequential approach.

The development is shown to be situated predominantly within Flood Zone 1; however the east boundary of the appears to lie within Flood Zone 3 of the Environment Agency Flood Map, which is defined the zone having a 1 in 100 year or greater annual probability of flooding (>1%) or a 1 in 200 year or greater annual probability of flooding from the sea (>0.5%) in any year.

Proposals for the site incorporate construction of 20No residential properties, and as such Table 2 of the Technical Guidance to the National Planning Policy Framework (March 2012) indicates that the development is classified as ‘more vulnerable’.

Table 1: Flood Risk Vulnerability and Flood Zone ‘Compatibility’ Flood Risk Essential Water Highly More Less Vulnerability Infrastructure compatible Vulnerable Vulnerable Vulnerable Classification Flood Zone 1      Zone Exception Zone 2   Test   required Exception Exception Test Zone 3a   Test  required required Exception Test Zone 3b     required

 Development is appropriate  Development should not be permitted

Report No. 13019/I/01 Project Details FRA – Residential Development at Burnley Road, Bacup Date. March 13

In accordance with the vulnerability table above, the type of development proposed is appropriate for the majority of the site.

Report No. 13019/I/01 Project Details FRA – Residential Development at Burnley Road, Bacup Date. March 13

3.0 Site Details

3.1 Location

The site is centred on ordnance survey grid reference SD 662 233.

An Ordnance Survey plan, indicating the location of the property is presented below.

Figure 1: Location Plan – Existing Development at Burley Road, Bacup

Proposed Development

Image produced from the Ordnance Survey Get‐a‐map service. Image reproduced with kind permission of Ordnance Survey and Ordnance Survey of Northern Ireland.

3.2 Former/Current Use

From historical Ordnance Survey Maps as far back as 1852 the site previously accommodated a cotton mill known as Shepherds Mill. The mill was auctioned off in 1929 to Messer’s JH Schofield Ltd of Rochdale, who put forward a plan for housing at the site, which was rejected by the Council of the time.

Later the mill was utilised for the manufacture of ammunitions by Lumb Hall Engineering, and for storage for the Women’s Land Army during WWII and was finally demolished in the 1970’s to accommodate the Bacup Leisure Centre.

Report No. 13019/I/01 Project Details FRA – Residential Development at Burnley Road, Bacup Date. March 13

The proposed development site was part of the Holmes Mill site; and following demolition of the mill building has remained undeveloped.

The topographical survey of the site is provided for information within Appendix A.

Figure 2: Historical Map of the Development Site (Circa 1893)

Image courtesy of www.oldmaps.co.uk

3.3 Proposals

Proposals for development at the site comprise construction of 20No residential dwellings; along with associated access road and off‐street parking.

The new properties are arranged into 6No terraced blocks; with vehicular access leading from Burley Road.

The proposed development layout plan has been provided within Appendix B of this report.

3.4 Boundaries

The subject site is situated near to the Lane Head area of Bacup; and is situated approximately 7 kilometres to the west of Todmorden; and 10 kilometres to the south of Burnley.

Report No. 13019/I/01 Project Details FRA – Residential Development at Burnley Road, Bacup Date. March 13

The northern boundary of the site is delineated by ‘The Bacup Hub’ an events venue which formerly housed the Bacup Leisure Centre. Existing residential property in the form of terraced cottages are located immediately to the south of the development.

Burnley Road forms the east boundary of the site; with further residential property located along the east side of the highway.

A small densely vegetated woodland forms delineates the west boundary of the site, with agricultural land associated with Holmes Barn Farm located beyond the woodland area.

Vehicular access into the site is available from Burnley Road.

Figure 3: Existing Site Viewed South West along Burnley Road

Source: D Metcalf

3.5 Topography

A topographical survey of the existing site indicates that a high point of 267.18mAOD is located along at the north west corner of the site; with a contrasting low point of 257.16mAOD at the south east corner.

The level of the proposed site access onto Burnley Road is recorded at 257.35mAOD.

Report No. 13019/I/01 Project Details FRA – Residential Development at Burnley Road, Bacup Date. March 13

3.6 Existing Drainage

The existing site is comprised of an undeveloped ‘greenfield’ plot, covering an area of 0.52 Hectares; and there is no positive drainage system currently serving the site.

It is evident from the topographical survey that there is a public sewer located within the carriageway of Burnley Road. Sewer records have been requested from United Utilities, however at the time of writing, the information had not been received.

3.7 History of Flooding

3.7.1 British Hydrological Society – Hydrological Events

A search on the British Hydrological Society Chronology of British Hydrological Events website (http://www.dundee.ac.uk/geography/cbhe) indicates no specific incidents of flooding within Bacup; however flooding within the upper reaches of the River Irwell was recorded in November 1901.

3.7.2 Internet Search for Historical Flooding

Undertaking an internet based search for flooding provided many recorded incidents of flooding within the lower reaches of the River Irwell near to Manchester and Salford; with the following incident recently recorded within the Bacup area:

 22nd June 2012 ‐ The River Irwell was reported to have caused flooding in Waterfoot, Rawtenstall, Stacksteads and Bacup after reaching its highest recorded level. The Environment Agency issued a flood warning at 7:25pm on 22nd June; which was no changed to ‘no longer in force’ by 10:22am on the 24th June. Video evidence indicates that Burnley Road to the front of the proposed application was flooded during this incident.

3.7.3 Irwell Catchment Flood Management Plan (December 2009)

The Irwell Catchment has a history of flooding with Salford near Manchester being the worst affected. In 1946 over 5000 properties were flooded from the River Irwell. A few years later Salford was flooded affecting 600 properties.

The area has settlements close to the banks of the rivers due in part to the industrialisation in the 19th century. This means communities are at risk of flooding from the Irwell and its many tributaries. Rochdale flooded in 1991 affecting over 80 properties and Crawshawbooth flooded in 1999 affecting over 50 properties. The main sources of flooding in the Irwell catchment are as follows:

Report No. 13019/I/01 Project Details FRA – Residential Development at Burnley Road, Bacup Date. March 13

 River flooding in the upper catchment affects the relatively small settlements and towns such as Littleborough, Rochdale, Bacup, Haslingden, Ramsbottom, Stubbins, Whitworth and Rawtenstall. There is a short time to peak in these generally narrow valleys, and the local population has insufficient time to react and reduce the consequences of flooding. The flooding regime in these areas is often described as “flashy”.  Surface water flooding is caused by water collecting or flowing over the surface before soaking into the ground or entering a watercourse. This type of flooding can occur throughout the catchment but usually only causes a low level of risk.  Sewer flooding is usually caused by an inadequate sewer capacity or blockages within the network. Sewer flooding is known to affect parts of Rawtenstall, Rochdale and Littleborough, as well as Bolton and Oldham and in part is thought to be due to run‐off surcharging the drainage systems. Sewers may also flood due to backing up as a result of high river water levels during times of flood. Areas within Salford and Manchester are known to be affected by this type of flooding, although there are limited records of this occurring in recent years. United Utilities have an ongoing programme of work to maintain and improve public sewers.  Even though the Irwell CFMP area contains areas of permeable bedrock at or near the land surface and some underlying aquifers groundwater flooding is not seen as a major issue in the area.

Specifically to the Rossendale Valley, the area has many culverts on the main river; some of these are collapsing or have low capacity. Build‐up of gravel and debris in the river might increase flood risk and gravel removal has been undertaken historically. Flood maps show around 650 properties are at risk of flooding in a 1% APE and by 2100 climate change is expected to increase this figure to 1,000 properties.

3.7.4 Rossendale Borough Council Level 1 SFRA (2008)

Historic incidents of flooding within the Rossendale area are listed within Appendix A of the Level 1 SFRA document, undertaken by Scott Wilson for Rossendale Borough Council, and published in May 2009.

Information obtained from the SFRA provides the following details of flooding along the route of the River Irwell at Bacup:

 1866; 1946; 1954; 1980 & 2007: Well documented cases of flooding caused by the River Irwell within the Rossendale Valley.  August 1849: River Irwell at Bacup.  July 1870: Fluvial. Heavy lightning storm and steep valley sides brought 'catastrophic' results.  July 1881: Fluvial. 'Catastrophic' results'. Mill properties along Burnley Road severely damaged.  August 1891: Fluvial. Streets flooded 2ft deep, mills were stopped.  November 1895: Fluvial. Quoted as 'greatest floods for 20 years'.  October 1998: Fluvial. Flooding in Weir.

Report No. 13019/I/01 Project Details FRA – Residential Development at Burnley Road, Bacup Date. March 13

 June 2002: Broad Clough ‐ Un‐named watercourse Burnley Road, Bacup ‐ Surface Water or Fluvial ‐ Flooded track to rear of Broad Clough Villas.  June 2002: Unnamed Non‐Main Watercourse ‐ Mill St & Holmes Lane, Bacup ‐ Fluvial ‐ Flooded Leisure Centre.  2006: River Irwell – Rossendale. Fluvial. Roads flooded.  January 2008: River Irwell – Bacup. Fluvial. House along Rochdale Road

3.7.4 Lancashire PFRA (2011)

Under the Flood Risk Regulations 2009, Lancashire County, Blackpool and Blackburn with Darwen Borough Councils are each designated as a Lead Local Flood Authority and as such, were required to undertake a Preliminary Flood Risk Assessment (PFRA).

An initial data collection exercise undertaken to inform the PFRA, revealed nearly 420 past flood incidents across the area from local authority records. In addition, interrogation of the United Utilities Sewer Incident Record System (SIRS) database uncovered a further 32 incidents of flooding due to the sewer system capacity being exceeded. The majority of the incidents identified related to flooding of minor roads or single properties.

Figure 4.1 and Table 4.1 extracted from the PFRA document, below and overleaf, illustrates a map and details relating to locally significant historic flooding incidents within the Lancashire area.

Figure 4: Summary of Significant Historic Floods in Lancashire

Extracted from Table 4.1 of the Lancashire PFRA Document (2011)

Report No. 13019/I/01 Project Details FRA – Residential Development at Burnley Road, Bacup Date. March 13

Figure 5: Past Flood Event Locations (Lancashire)

Extracted from Figure 4.1 of the Lancashire PFRA Document (2011)

Report No. 13019/I/01 Project Details FRA – Residential Development at Burnley Road, Bacup Date. March 13

4.0 Flooding Mechanisms

Table 2: Sources of Flooding Source/Pathway Significant? Comment/Reason Fluvial Yes River Irwell; Unnamed Watercourse. Tidal/Coastal No Canal No Pluvial (urban drainage) Yes Surface Water Runoff Management Groundwater No Overland flow Yes Located within a steep sided valley Blockage Yes Culverted watercourse Infrastructure failure Yes Culverted watercourse Rainfall Ponding No

4.1 Fluvial: River Irwell

The River Irwell is a 39‐mile (63 km) long river which flows through the Irwell Valley in North West England. Its source is at Irwell Springs on Deerplay Moor, approximately 1.5 miles (2.4 km) north of Bacup. The river forms the boundary between the cities of Manchester and Salford and empties into the River Mersey near Irlam.

Information from the Rossendale SFRA and River Irwell CFMP documents indicates that the fluvial flooding mechanism within the upper catchment is characterized by water levels within the streams and river rising rapidly in response to rainfall events. This is believed to be largely due to a combination of steep sided valleys, modified field drainage and impermeable geology and soils; and the time for flows to peak within the river network is typically less than 2 hours, often giving the local population insufficient time to react and reduce the consequence of flooding.

High up in the catchment, mixed moorland and blanket bog are characteristic of the landscape, whilst pasture land dominates the flatter hill slopes and valleys lower down in the upper catchment.

Urban development is confined to the narrow valley floors of the upper River Irwell. In the main urban areas of Rawtenstall, Haslingden, Bacup, Waterfoot and Stacksteads, rivers are constrained by culverts, retaining walls and weirs.

The River Irwell is culverted for a short distance adjacent to the development; and the Environment Agency has provided modelled flood level data for locations both upstream and downstream of the culverted section along Burnley Road.

As such, the impact of flooding at the application site due to overtopping of the open channel sections of watercourse; along with the consequence of inundation resulting from structural collapse or blockage within the culverted section of the river must be considered in more detail. 14

Report No. 13019/I/01 Project Details FRA – Residential Development at Burnley Road, Bacup Date. March 13

4.1.1 Modelled Flood Level Data

The information provided by the Environment Agency relating to modelled flood levels within the River Irwell near to the application site is tabulated below.

Table 3: Environment Agency Modelled Flood Levels for the River Irwell at Bacup Flood Level Flood Level Flood Level Flood Level Return Period Point Ref. 1 Point Ref. 2 Point Ref. 3 Point Ref. 4 1 in 10 years 257.8 257.56 255.52 255.40 1 in 20 years 257.91 257.69 255.59 255.46 1 in 75 years 258.22 258.08 255.71 255.58 1 in 100 years 258.32 258.19 255.74 255.60 1 in 100 years + 258.66 259.12 256.09 255.73 20% CC 1 in 1000 years 259.46 259.43 256.22 255.98

4.1.2 Overtopping: 1 in 100 year Event

Undertaking a review topographical and Ordnance Survey maps for the local area indicates that the level of Burnley Road adjacent to the watercourse at each of the modelled flood nodes is as follows:

 Point Ref. 1: 259.800mAOD  Point Ref. 2: 259.200mAOD  Point Ref. 3: 256.990mAOD  Point Ref. 4: 256.300mAOD

A direct comparison indicates that the resultant water levels anticipated during the 1 in 100 year event are lower than Burnley Road.

4.1.3 Overtopping: 1 in 100 year + Climate Change Event

Unfortunately modelled levels for the 1 in 100 year plus 20% climate change event within the River Irwell have not been provided.

In such cases it is considered acceptable to use modelled design flows to interpolate or extrapolate known flood levels, to estimate the effect of climate change within the watercourse.

Increasing the 1 in 100 year design flows by a factor of 20% is considered appropriate to estimate future climate change in accordance with the requirements of Table 5 of the NPPF Guidance Document (2012); and therefore extrapolating the modelled data provides a simple evaluation of the corresponding increase in flood level within the adjacent river.

The resulting values are provided for reference within Table 3 above.

Report No. 13019/I/01 Project Details FRA – Residential Development at Burnley Road, Bacup Date. March 13

Comparison indicates that the resulting water levels during the 1 in 100 year plus 20% climate change event are lower than Burnley Road.

4.1.4 Overtopping: Extreme 1 in 1000 year Event

During the extreme 1 in 1000 year event, the modelled flood level at Point Ref. 2, which is located at the head of the culverted section of watercourse, is shown to be elevated above the road level recorded for Burnley Road.

Figure 6: River Irwell Viewed Upstream from the Culvert Headwall at Cooper Street

Source: D Metcalf

Stone walls extend approximately 1 metre above the footpath along the open channel section of the River Irwell, upstream of Cooper Street, as illustrated within Figure 6 above; and provide some protection against flooding within Bacup.

However the condition of the stone wall is very poor, with large gaps visible between the stonework in places; which is liable to allow flood water to spill into the adjacent highway; where it will flow downhill in a southerly direction along Burnley Road towards Bacup centre.

Report No. 13019/I/01 Project Details FRA – Residential Development at Burnley Road, Bacup Date. March 13

The resultant depth of flooding at the location of the proposed site access into the development is difficult to predict; however for the purposes of this assessment it has been taken to be the difference between the flood water level at Point Ref. 2 and the adjacent road level i.e. 259.43 – 259.20 = 0.23 metres.

Figure 7: Anticipated Flood Conveyance Route South Along Burnley Road

Flood water will spill over or be forced through the stone wall into Burnley Road

Source: D Metcalf

4.1.5 Danger to People from Overtopping

Adopting a simple approach as recommended in DEFRA report FD2320/TR2 and utilising Table 12.1 of that report, the danger classification resulting from overtopping of the existing flood defence during extreme flood conditions, is considered to be ‘danger for some’, as the direct flow route from the watercourse to the site is approximately 100 metres away; and the head of flood water above the adjacent road has been taken to be 0.23m (see above).

The results are shown below within Table 4.

Report No. 13019/I/01 Project Details FRA – Residential Development at Burnley Road, Bacup Date. March 13

Table 4: Danger to People from Overtopping Relative to Distance from Defence1 Distance from Head Above Crest Level (m) Breach (m) 0.5 1 2 3 100  250 500 1000 1500 2000 Key Danger for none Danger for some e.g. young, elderly and infirm Danger for most e.g. general public Danger for all e.g. including rescue services

4.1.6 Infrastructure Failure: Blockage or Structural Failure & Overland Flow

The River Irwell is culverted intermittently along its route through Bacup.

Information obtained from the Rossendale Borough Council SFRA indicates that historical flooding within the Bacup and surrounding areas are generally caused by insufficient channel capacity; and numerous blocked culverts resulting from sedimentation and shoaling, which act to restrict flows and raise water levels which results in overtopping. It is further noted that the many culverts located within the Upper Irwell Catchment, are of varying condition.

The culverts within Bacup are predominantly of stone arch construction; however one section within Bacup town centre was replaced using concrete sections in 2008.

In the event of a blockage, flood water within the river will back up on the upstream side of the obstruction. If the water level should reach the culvert top it would most likely overtop the upstream headwall of the culvert structure. This is likely to cause flooding to nearby property; with nearby Burnley Road forming an overland flow route southwards towards Bacup town centre.

The capacity of the watercourse through the culverted section has not been provided by the Environment Agency, and as such it is difficult to calculate the probability of the culvert’s capacity being exceeded during flood conditions within the river.

However from the known route of the River Irwell, the headwall of the culverted section of watercourse is located a distance approximating 100 metres to the north boundary of the proposed development.

1 Note: Table copied from Table 12.1, Section 12, FD2320/TR2 18

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Figure 8: River Irwell Viewed Upstream from the Culvert Headwall at Cooper Street

Source: D Metcalf

Local topography of the area indicates that should blockage or collapse of the culverted watercourse occur upstream of the site; flood water overtopping the headwall structure, may be channelled downhill towards the site (see Figure 7).

Flood water is likely to spread out as it extends away from the route of the culvert; and therefore the depth of flooding at the proposed development, approximately 100 metres away, is likely to be shallower than at the location of initial flooding. However, due to the proximity of the upstream headwall to the application site it is considered that inundation at the proposed site access via this mechanism is a possibility.

The watercourse is classified as ‘Main River’ and is therefore the responsibility of the Environment Agency.

In consideration of the probability of flooding to the application site, it is highlighted that regular inspection and maintenance of the culvert is undertaken by the Environment Agency; and therefore whilst the condition of the culvert is unknown, it is anticipated that the probability of complete structural failure is deemed to be low.

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4.1.6 Conclusion

The application site is shown to lie predominantly within Flood Zone 1, and the location of the site access is shown to lie within Flood Zone 3 of the Environment Agency Flood Map.

The limited extent of the modelled flood data provided indicates that the site access is likely to be compromised during the extreme 1 in 1000 year event; thereby placing Burnley Road within Flood Zone 2.

However, due to the topography of the local area, the poor condition of the stone walls above ground level along the canalised banks of the river through Bacup; and the availability of a flood conveyance route along Burnley Road, it is possible that overtopping of the banks and walls along the west side of the River Irwell may occur during the more frequent flood events i.e. 1 in 100 year flood event; thereby concurring with the current Flood Map.

Further confirmation of this is provided via the large number of recorded incidents of flooding along Burnley Road, with the most recent event occurring in June 2012.

In conclusion, the River Irwell presents a medium to high risk of flooding at the proposed site access; and presents a low risk within the main development area of the site.

4.2 Fluvial: Unnamed Watercourse

The unnamed watercourse is a small tributary of the River Irwell, and flows generally in an easterly direction, within the vicinity of the proposed development.

The watercourse rises to the west side of Holmes Barns Farm and flows in open channel towards Albert Terrace, where it is culverted via a 525mm diameter pipe for its remaining route down the hillside towards the River Irwell.

It is likely that flow from this stream was used to power Holmes Mill which was formerly located at the site.

The structural integrity and the route of the existing culvert are currently unknown; however it appears that the culvert may follow the south boundary of the proposed development; discharging into the River Irwell immediately downstream of the culvert, as shown overleaf in Figures 8 and 9.

Due to the proximity of the unnamed watercourse to the proposed development and topography of the surrounding area, direct flooding via overtopping of the open channel section of watercourse, along with the impact of flooding via structural collapse or blockage within the culverted section must be considered in more detail.

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Figure 9: Approximate Route of Culverted Watercourse

Culvert

Figure 10: Confluence of the Unnamed Watercourse with the River Irwell

Culvert Exit

Source: D Metcalf

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4.2.1 Estimation of Flows within the Unnamed Watercourse

It is necessary to estimate the 1 in 100 year flow within the unnamed watercourse in order to evaluate the flood risk posed by the culvert and the small section of open channel within the development site.

IOH124 Method for Small Catchments

The catchment serving the unnamed watercourse is very small at 8.7 Hectares or 0.09 km2 and wholly rural in nature and therefore flow has been estimated using the IOH124 Method for calculation flows from small catchments.

QBAR is estimated using Equation 4‐1, outlined below:

Equation 4‐1 0.89 1.17 2.17 QBARRURAL = 0.00108AREA SAAR SOIL

Where QBAR RURAL = mean annual flood in the as‐rural state AREA = catchment area (km2) = 8.7Ha = 0.087km2 SAAR = standard average annual rainfall (mm) = 1400mm (from MicroDrainage Source Control) SOIL = soil type index = 0.50 (from MicroDrainage Source Control)

The full calculation results for QBAR rural obtained from the IOH124 method, is given in Appendix D of this report. A value of 108.1l/s has been estimated. The catchment is totally rural in nature and as such an adjustment to the QBAR calculation to account for urbanisation is not required.

The 1 in 100 year flow within the unnamed watercourse is estimated as 224.8l/s or 0.225m3/s.

Consideration has been given to take into account the potential effects of climate change and sea level rise over the next 100 years in accordance with the NPPF (2012). A 1 in 100 year plus climate change return period incorporating the precautionary sensitivity range of a 20% increase in peak river flows, provides a design flow of 0.270m³/s.

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Figure 11: Sketch Illustrating Route of Unnamed Watercourse Upstream of the Site

River Irwell

Proposed Development

Unnamed Watercourse

Source: Streetmap

4.2.2 Capacity of the Upstream Channel

The open channel section of the unnamed watercourse upstream of the culvert is generally trapezoidal in cross section.

Figure 12: Estimated Catchment Area – Unnamed Watercourse

Unnamed Watercourse Catchment Area = 8.7Ha

Observations made during a site visit in March 2013 indicate that the channel exhibits the following approximate dimensions; bed width of 0.5m; top width of 1.0m and a depth approximating 0.75m. 23

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Using Manning’s Equation (see Equation 4‐2 below) the bankfull capacity of the open channel is estimated to be 2.42m3/s.

Equation 4‐2 2/3 1/2 3 Flow Q = AR x S0 = 2.42 m /s n

Where A = Channel cross sectional area (m2) = 0.5625m2 R = hydraulic radius (m) = A/P = 0.270m P = Wetted perimeter of the channel (m) = 2.0811m S0 = Representative bed slope or gradient (m/m) = (325‐275)/294 = 0.170 n = Manning’s roughness coefficient = 0.04 (i.e. mountainous stream) Mountainous Streams: no vegetation in channel, banks usually steep, trees and brush along banks submerged during high water levels. Bed: cobbles with larger boulders.

In conclusion the open channel section of the watercourse has sufficient capacity to convey the 1 in 100 year plus 20% climate change flow.

Figure 13: Typical Cross Section Through Open Channel Section of Unnamed Watercourse

Furthermore, it is estimated that during the 1 in 100 year plus 20% climate change flood event, the depth of water within the channel approximates 0.191 metres.

4.2.3 Capacity of Culverted Watercourse

From observation and Chapter 6 of CIRIA 689 ‘Culvert Design and Operation Guide’; it has been identified that the culverted section of the unnamed watercourse exhibits Type 1 Flow or Free Flow Inlet Control.

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This is the type of flow is controlled by the culvert inlet with supercritical flow through some or the entire culvert barrel. The inlet causes a large energy loss and drop in water level; and the flow accelerates as it enters into the culvert.

If the tailwater depth is below the sequent depth for the formation of a hydraulic jump, then supercritical flow extends over the full length of the barrel. However, if the tailwater depth exceeds the sequent depth, a hydraulic jump will form in the barrel of the culvert and flow changes from supercritical to subcritical. The latter condition may cause the culvert to prime i.e. flow full throughout, if the tailwater level rises above the outlet soffit, changing the flow condition to Type 5.

Type 5 culvert flows represent full flow outlet control; where both the inlet and outlet of the culvert are fully submerged and the barrel flows full or surcharged. The tailwater is controlled by the downstream channel and the headwater is determined by the tailwater level and head losses within the culvert structure.

Depending on the elevation of water within the receiving River Irwell, both types of flow are considered possible within the existing culvert.

Figure 14: Type 1 & Type 5 Culvert Flow

Source: CIRIA C697

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Depending on the elevation of water within the receiving River Irwell, both types of flow are considered possible within the existing culvert.

Hydraulic Assessment for Type 1 Flow

Estimation of Discharge Intensity & Selection of Calculation Approach

Equation 4‐3

Discharge Intensity Qi = 1.811Q = 3.12 0.5 AbD

Where Q = Discharge (m3/s) = 0.27m3/s 2 2 Ab = Cross sectional area of the culvert barrel (m ) = 0.216m D = Height of the culvert barrel (m) = 0.525m 1.811 = dimensionless constant

Qi < 3.5: Free flow calculation Qi > 4.0: Submerged flow calculation 3.5 < Qi < 4.0: Transition between free and submerged flow calculation

Figure 15: Culvert Inlet under Type 1 Free Flow Conditions

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Calculation of Headwater Depth for Free Flow Inlet Control

Equation 4‐4 Inlet Control Equations: M Esh = Esc + k x [1.811Q] – 0.5S0 0.5 D D [ AbD ]

Where Esh = Specific energy of headwater (m) Esc = Specific energy at critical depth (m) k = constant = 0.0098 (Table A1.3 CIRIA 689) M = constant = 2.0 (Table A1.3 CIRIA 689) S0 = 18m/138m = 0.13

Esc = 3/2 x yc

2 Where yc = critical depth (m) represented by the equation: Q W = 1 3 gAc

3 For Q = 0.27m /s, by iteration the corresponding yc = 0.3515m

Therefore Esc = 3/2 x 0.3515 = 0.527

Esh = 1.0038 + 0.0957 – 0.065 = 1.0345 and Esh = 1.0345 x 0.525 = 0.543m D

The specific energy Esh is obtained by multiplying the headwater ratio by the barrel height; and the depth of water upstream of the culvert inlet yf is given by multiplying the barrel height and deducting the velocity head.

Equation 4‐5 Velocity Head Loss at Culvert Inlet: 2 2 hi = ki x [Vuc – Vb ] [ 2g ]

Where ki = inlet loss coefficient = 0.5 Vb = mean velocity in culvert barrel at outlet (m/s) Vuc = mean velocity in upstream channel (m/s)

2 Vb = Q/Ab, where Ab = cross sectional area of flow in culvert barrel = 0.1541m

Therefore Vb = 0.27 / 0.216 = 1.25

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2 And Vuc = Q/Auc, where Auc = cross sectional area of flow in upstream channel = 0.1078m

Therefore Vuc = 0.27 / 0.1078 = 2.50

And hi = 0.119

Headwater depth Yf = 0.543 – 0.119 = 0.424m

The overall depth of the upstream channel 0.75 metres and therefore during the 1 in 100 year plus 20% climate change flood event within the unnamed watercourse, and assuming free discharge into the River Irwell, it is anticipated that flood water will remain within the confines of the channel and culvert.

4.2.4 Hydraulic Failure

The culvert systems within the upper catchment of the River Irwell are documented to have flood issues resulting from sedimentation and other hydraulic issues.

In the event of a partial blockage within the culvert, upstream of the proposed development, reducing the cross sectional area for example by 50%, the capacity of the existing culvert will be severely reduced, resulting in increased headwater levels at the culvert inlet structure.

Figure 16 overleaf illustrates the possible hydraulic failure modes which may occur in association with the culverted watercourse.

Figure 16: Culvert Inlet with 50% Blockage

50% Blockage

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Figure 17: Possible Hydraulic Failure Modes

Source: CIRIA C697

Repeating the calculations from Section 4.2.3:

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Equation 4‐6

Discharge Intensity Qi = 1.811Q = 8.84 0.5 AbD

Where Q = Discharge (m3/s) = 0.27m3/s 2 2 Ab = Cross sectional area of the culvert barrel (m ) = 0.108m D = Height of the culvert barrel (m) = 0.2625m 1.811 = dimensionless constant

Qi < 3.5: Free flow calculation Qi > 4.0: Submerged flow calculation 3.5 < Qi < 4.0: Transition between free and submerged flow calculation

Equation 4‐7 Headwater Depth for Submerged Inlet Control: 2 Esh = c x [1.811Q] + Y – 0.5S0 0.5 D [ AbD ]

Where Esh = Specific energy of headwater (m) c = constant = 0.398 (Table A1.3 CIRIA 689) Y = constant = 0.67 (Table A1.3 CIRIA 689) S0 = 18m/138m = 0.13

Esh = 31.10 + 0.67 – 0.065 = 31.705 and Esh = 31.705 x 0.2625 = 8.322m D

Equation 4‐8 Velocity Head Loss at Blocked Culvert Inlet: 2 2 hi = ki x [Vuc – Vb ] [ 2g ]

Where ki = inlet loss coefficient = 0.5 Vb = mean velocity in culvert barrel at outlet (m/s) Vuc = mean velocity in upstream channel (m/s)

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2 Vb = Q/Ab, where Ab = cross sectional area of flow in culvert barrel = 0.108m

Therefore Vb = 0.27 / 0.108 = 2.50

2 And Vuc = Q/Auc, where Auc = cross sectional area of flow in upstream channel = 0.1078m

Therefore Vuc = 0.27 / 0.1078 = 2.50

And hi = 0

Headwater depth Yf = 8.322 – 0 = 8.322m

As such it is considered that under such conditions, the inlet to the culvert will become overtopped; and flood water will be conveyed along an overland flow route following natural topography towards Burnley Road; causing flooding along the south boundary of the development site.

4.2.6 Conclusion

In conclusion under normal flow conditions, the unnamed watercourse presents a low flood risk to the proposed development; however in the event of hydraulic failure such s blockage or structural collapse, then the risk of flooding within the proposed development is increased.

4.3 Surface Water Runoff

4.3.1 Existing Drainage Regime

The existing site is composed of a largely undeveloped area, with dense woodland located along the west boundary; and existing development along the north and south boundaries of the site. A building accommodating a gas governor is situated within the south east corner of the development site.

Vehicular access is currently available from Burnley Road.

The surfacing within the existing site is composed of short grass; with longer grass and shrubs along the perimeter.

In conclusion the site may be classified as greenfield development.

From observation and a review of the topographical survey; the site is fairly steep; with a fall approximating 10 metres in a south easterly direction across the site.

A culverted watercourse has been identified to run along the south boundary of the development; discharging into the River Irwell at Laurel Street.

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In the absence of a positive drainage system within the exiting site, it is envisaged that surface water runoff is currently allowed to flow overland, following the natural topography of the site towards Burnley Road.

4.3.2 Existing Greenfield Runoff Rates

Table 1 of the Joint DEFRA/EA R&D Technical Report ‘Preliminary Rainfall Runoff Management for Developments’ (W5‐074/A/TR/1) published in January 2012 provides the appropriate methodologies for calculating peak greenfield runoff rates.

For developments smaller than 50 Hectares in size, one of the two following approaches may be utilised:

 The Institute of Hydrology (IH) Report 124 Flood Estimation for Small Catchments (1994) method can be used to estimate the greenfield site flow rate, QBAR (the Mean Annual Flood).  The Index Flood, QMED (the median of the set of annual maximum flood peaks) regression equation that forms part of the FEH statistical method can also be used where the appropriate parameters are known or can be derived/ estimated.

Where developments are smaller than 50Ha, the analysis for determining the greenfield index flood flow rate should use 50Ha in the formula and linearly interpolate the flow rate value based on the ratio of the development area.

FSSR 14 can be used to convert QMED to QBAR.

FSSR 2 and 14 regional growth curve factors can be used to calculate the greenfield peak flow rates for 1, 30 and 100 year return periods.

For the purposes of this assessment, the IOH124 Method for Small Catchments has been adopted; utilising the Source Control Module of industry standard software known as MicroDrainage Windes.

A summary of the calculation results is tabulated below; with full output provided within Appendix E of this report.

Table 5: Existing Greenfield Runoff Rates (Site Area = 0.52Ha) Peak Flow Peak Flow Return Hydrometric Peak Flow Q (l/s) Rate 50Ha Rate Site Period Area BAR Rate (l/s/ha) (l/s) (l/s) 1 in 1 year 540.5 10.81 5.6 1 in 30 year 10 621.2 1053.2 21.06 11.0 1 in 100 year 1292.1 25.84 13.4

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4.3.3 Proposed Drainage Regime

The hierarchy for disposal of surface water from new development is outlined within The Building Regulations Approved Document H and specifies the following methods in order of preference:

 Infiltration via soakaway or other suitable infiltration device  Discharge to watercourse  Discharge to public sewer.

Infiltration

A site investigation report for the proposed development is not currently available. Therefore in order to assess the potential for infiltration methods to dispose of surface water from the development, an investigation of the general ground conditions within the Bacup area was undertaken.

Catchment wide data for the site was obtained from the FEH CD‐ROM (V3.0), which indicates that, the SPRHOST (Standard Percentage Runoff) for the site has a value of 33.4%; with a value of 50% indicated by MicroDrainage Source Control. These values are fairly high and are considered generally to represent ground which is not suited for dissipation of surface water flows into the ground.

To further investigate, a review of historical borehole logs within the general vicinity of the development from the British Geological Society records, indicates that ground is composed of clay overlying clayey shales; silty clays; or clayey gravels. The indication of clay suggests low permeability for infiltration purposes. Therefore the use of soakaways and other infiltration techniques have been discounted from the proposed drainage strategy for the development.

A copy of the borehole logs which have been reviewed is provided within Appendix F of this report.

Information from the National Soil Resource Institute: www.landis.org.uk/soilscapes details the development area as being situated on restored soils mostly from quarry and opencast spoil with highly variable drainage characteristics.

It is noted however that the large number of natural streams which emanate from the high areas surrounding Bacup do not provide a positive case for infiltration; as it is considered likely that most surface water drainage within the area is discharged to watercourse.

Furthermore in accordance with CIRIA 697 ‘The SUDS Manual’ infiltration methods should not be used on sites with steep slopes; such as the proposed development.

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Watercourse

The existing drainage regime at the site comprises overland flow directed via natural topography towards Burnley Road.

A culverted watercourse is located along the south boundary of the site; and as the disposal of surface water via infiltration methods is deemed unfeasible, it is recommended that the on‐site drainage system directs flows towards the culverted watercourse.

Sewer

In the event that discharge to watercourse is deemed impractical; and evidence can be provided to support this, then surface water from the site may be discharged to the public surface water sewer or combined sewer.

It is noted however that United Utilities do not have to accept surface water runoff from the development into the public sewer network; and as such in the event that this is the only viable solution for disposal of surface water from the site; then it is highly recommended that the Developer undertakes discussions with United Utilities at the earliest opportunity.

Surface Water Drainage Design Criteria

The following criteria for designing surface water drainage systems for new development have been extracted from the Joint DEFRA/EA R&D Technical Report ‘Preliminary Rainfall Runoff Management for Developments’ (W5‐074/A/TR/1) published in January 2012.

1. Discharge Rate

The Environment Agency normally require that, for the range of annual flow rate probabilities, up to and including the 1% annual probability (1 in 100 year event) the developed rate of runoff into a watercourse should be no greater than the undeveloped rate of runoff for the same event based on the calculation of QBAR or QMED and the use of FSSR growth curves.

Exceptions only apply where it is not practical to achieve this due to either constraints on the size of the hydraulic control unit, or excessive storage volumes. The purpose of this is to retain a natural flow regime in the receiving watercourse and not increase peak rates of flow for events of an annual probability greater than 1%. Three annual probabilities are used to define discharge compliance limits though the critical criteria are for the lowest and highest frequency events; 100% (1 year), 3.33% (30 year) and 1% (100 year).

2. 1 in 1 year Design Event

The 1 in 1 year event is the highest probability event to be specifically considered to ensure that flows to the watercourse are tightly controlled for frequent events to provide good morphological conditions.

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3. 1 in 30 year Design Event

The 1 in 30 year event is of importance because of its linkage with the level of service requirement of Sewers for Adoption 7th Edition, which requires that surface water sewers should be capable of carrying the 1 in 30 year flows generated by a development within the system without causing flooding to any part of the site.

4. 1 in 100 year Design Event

The 1 in 100 year event has been selected since it represents the boundary between high and medium risks of fluvial flooding defined by the National Planning policy Framework (2012) and also recognises that it is not practicable to fully limit flows for the most extreme events. Also Sewers for Adoption 7th Edition recognises that, during extreme wet weather, the capacity of surface water sewers may be inadequate.

Sewers for Adoption 7th Edition requires that the site layout should be such that internal property flooding does not result, by demonstrating safe above ground flow paths.

The return period for this analysis is not specified, but it is recommended that 1% annual probability event (i.e. an event with a return period of 100 years) is used.

5. Flood Flows

Runoff up to the 1 in 100 year return period should preferably be managed within the site at designated temporary storage locations unless it can be shown to have no material impact by leaving the site in terms of nuisance or damage, or increase river flow during periods of fluvial flooding. Analysis for overland flood flows within the site will need to use appropriate duration events which may be different to critical events for designing surface water control storage structures.

6. Surface Water Runoff Volume

Theoretically the surface water runoff volume from a site should be limited to the greenfield runoff volume for all event frequencies. However this is technically extremely difficult to achieve and therefore compliance to two criteria on runoff volume is required. a. Interception: Where possible, infiltration or other techniques are to be used to try and achieve zero discharge to receiving waters for rainfall depths up to 5mm. b. Additional Runoff Due to Development: The difference in runoff volume pre‐ and post‐ development for the 100 year 6 hour event, (the additional runoff generated) should be disposed of by way of infiltration, or if this is not feasible due to soil type, discharged from the site at flow rates below 2 l/s/ha, unless Point 9 (See below) is applicable to the development.

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7. Climate Change

In accordance with Table 5 of the Technical Guidance for the NPPF (2012), a 20% increase to rainfall intensities should be applied for development with a lifetime up to 2085; and 30% for development with a prospective lifetime beyond this date.

Residential development is generally expected to have a design life of 100 years; and as such an additional 30% must be applied within the drainage design for the proposed development situated off Burnley Road in Bacup.

8. Urban Creep

Urban creep is now an acknowledged issue which results in an increase in runoff from an estate over time. An allowance should be made by factoring the impermeability percentage by 1.1 (10% increase) unless a more precautionary requirement is specified by the local planning authority.

9. Minimum Limit of Discharge Rate

A practicable minimum limit on the discharge rate from a flow attenuation device is often a compromise between attenuating to a satisfactorily low flow rate while keeping the risk of blockage to an acceptable level.

This limit is set at 5 litres per second, using an appropriate vortex or other flow control device.

Where sedimentation could be an issue, the minimum size of orifice for controlling flow from an attenuation device should normally be 150mm laid at a gradient not flatter than 1 in 150, which meets the requirements of Sewers for Adoption 7th Edition.

4.3.4 Sustainable Urban Drainage Systems (SUDS)

Due to the nature of the proposals, the impermeable area within the site will be increased following development. There will therefore be an increase in surface water runoff rates and volumes from the site when it is developed.

The Statutory Authorities will request that the runoff from the proposed development is restricted to existing greenfield runoff rates or a minimum of 5l/s.

Additionally, the Local Authority; United Utilities and Environment Agency will require that adequate pollution control is incorporated into the drainage system in order to prevent deterioration of the quality of the water environment.

To reduce the impact of surface water runoff from the development in accordance with the requirements of the Statutory Authorities, the employment of SUDS techniques to limit runoff volumes and rates from the site are recommended.

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This section provides an indication of the possible SUDS techniques which could be employed on the site to balance flows within the proposed development. SUDS techniques are also able to provide treatment to the runoff to remove a proportion of the pollution and protect the quality of the downstream watercourses. Following guidance from CIRIA Report C522 the following levels of treatment should be provided: • Roofs – 1 level • Driveways – 1 level • Roads and communal parking areas – 2 levels.

The level of treatment indicates the number of SUDS techniques that will be used to treat pollution. For example if two levels are required the runoff may enter a filter drain that leads to a basin or pond before outfall.

The implementation of source control techniques means in practice there will be little outflow for a 1 in 1 year storm as most of the rainfall will be held within the system and will disperse via evapotranspiration.

Undertaking an assessment using the SUDS Planner Module within MicroDrainage Windes revealed that a number of different methods would be suitable for inclusion within the proposed drainage strategy for the development. A summary of the results is tabulated below:

Table 6: SUDS Planner Results SUDS Criteria Rank 1 Rank 2 Rank 3 Infiltration Hydrological Permeable Paving Green Roof Trench/Soakaway Online/Offline Land Use Filtration Techniques Permeable Paving Storage Online/Offline Site Features Green Roofs Filtration Techniques Storage Community & Online/Offline Grassed Filter Strip Bioretention area Environment Storage Economics & Wet Ponds Grassed Filter Strip Dry Detention Maintenance Online/Offline Total Green Roof Permeable Paving Storage

It is noted that the precise combination of methods used will be dependent upon the site constraints identified at the final design stage.

1. Permeable Paving

As investigated within Section 3.3.1 of this report, groundwater recharge via infiltration is not a viable option for this site, due to underlying ground conditions within the area containing the site.

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However, permeable paving may be used to provide shallow attenuation of surface water runoff; prior to discharge into a receiving watercourse or on‐site drainage system.

It is unlikely that United Utilities will adopt a permeable paving drainage solution as part of a Section 104 Agreement; and an underground storage structure is their favoured method for providing attenuation volume within a drainage system which will become part of the public sewer network.

It is recommended therefore that permeable paving is restricted to car park areas, within the proposed development plan.

2. Online/Offline Storage

Due to the limited space available within the development to provide sufficient volume to attenuate flows to greenfield run off rates; online structures such as oversized pipes or box culvert sections may be easily placed within proposed road network within the development to provide ease of access for maintenance purposes.

3. Green Roof

Green roofs comprise a multi‐layered system that covers the roof of a building with vegetation cover, and/or landscaping over a drainage layer.

They are designed to intercept and retain rainfall thereby reducing the volume and attenuating peak surface water flows.

The following information regarding green roof technology has been extracted from CIRIA Document C697 ‘The SUDs Manual’.

Key Design Criteria:  Designed for interception storage.  Minimum roof pitch 1 in 80, maximum 1 in 3.  Structural roof strength must provide for the additional load of saturated green roof media.  Hydraulic design to BS EN 12056‐3.  Multiple outlets to reduce the risk from blockage.  Lightweight soil medium and appropriate vegetation.

Advantages:  Mimic pre‐development state of the building footprint (greenfield development).  Good removal capability if atmospherically deposited urban pollutants.  Can be applied in high density developments.  Can sometimes be retro‐fitted.  Provides ecological, aesthetic and amenity benefits.  No additional land take required.  Improves air quality.

Report No. 13019/I/01 Project Details FRA – Residential Development at Burnley Road, Bacup Date. March 13

 Helps to retain higher humidity levels in city areas.  Insulated buildings against temperature extremes.  Reduces the expansion/contraction of roof membranes.  Provides sound absorption.

Disadvantages:  Increased cost compared to traditional roof materials.  Inappropriate for steep sloping roofs.  Opportunities for retro‐fitting may be limited by existing roof structure.  Maintenance of roof vegetation.  Any damage to the waterproof membrane is critical, since water is encouraged to remain on the roof.

Maintenance Requirements:  Irrigation is required during establishment of vegetation.  Inspection for bare patches and replacement of plants.  Litter removal (depending on setting and use).

Whilst it is recommended that this SUDS technique is considered by the developer, it is noted that the cost of installation; along with the structural strength requirements of the proposed roof structures may be prohibitive for the inclusion of green roof technology for this development.

4. Rainwater Harvesting

Following development the volume of surface water runoff leaving the site is likely to be increased; owing to an increase in roof and hardstanding areas within the site.

It is therefore recommended that rainwater harvesting is considered for inclusion within the drainage strategy for the development to provide a source of non‐potable water for purposes such as car washing; and watering gardens etc…

This SUDS solution, like green roof technology, is also designed to provide interception storage i.e. acts to reduce the volume of surface water leaving the proposed development; thereby helping to alleviate the current pressures on the receiving field dyke.

In the event that the proposed development is to be assessed as part of BREEAM’s Code for Sustainable Homes; the inclusion of rainwater harvesting, will help to achieve the mandatory requirements set out for Category 4 SUR1 Surface Water, within the Code.

It is noted that collection of rainwater via water butts is not classed as a rainwater harvesting solution.

Report No. 13019/I/01 Project Details FRA – Residential Development at Burnley Road, Bacup Date. March 13

4.3.5 Residual Flood Risk

In order to prevent exacerbation of surface flooding along Burnley Road during extreme rainfall events, it is recommended that the proposed drainage system is designed such that there will be no residual risk from flooding due to surface water discharge for storms with a return period of 100 years or less (with a 30% increase for climate change);

4.4 Groundwater

The document Lancashire Area PFRA published in 2011 indicates that the Environment Agency and Local Authority have no record of any historical locally significant flooding incidences arising from groundwater within Bacup.

Figure 17 provides an indication of the probability of groundwater flooding throughout the East Lancashire area.

It is therefore concluded that groundwater presents a low risk of flooding at the application site.

4.5 Overland Flow

The site is located within a steep sided valley; with agricultural land located at a higher elevation to the west of the site.

Furthermore, as previously discussed within Section 4.2 of this report, in the event that blockage or structural failure of the culverted watercourse which traverses along the south boundary of the site was to occur, the culvert inlet is likely to become overtopped.

Water will follow the natural topography of the area, downhill through the site towards Burnley Road.

As such overland flows are considered to present a flood risk to the proposed development.

4.6 Infrastructure Failure: Reservoirs

Undertaking a check of the Environment Agency Flood Maps indicates that the proposed development is located outside of the area likely to be affected in the event that structural failure should occur at a nearby reservoir.

4.7 Ponding

The topographical survey of the proposed development does not highlight any existing pond systems or localised low points within the existing site, where ponding is likely to occur during heavy rainfall.

As such, this mechanism is deemed to present a low flood risk to the development.

Report No. 13019/I/01 Project Details FRA – Residential Development at Burnley Road, Bacup Date. March 13

Figure 18: Areas Susceptible to Groundwater Flooding (2011)

Burnley Road, Bacup

Image courtesy of Lancashire Area PFRA (2011)

Report No. 13019/I/01 Project Details FRA – Residential Development at Burnley Road, Bacup Date. March 13

5.0 Material Consideration In Respect of the National Planning Policy Framework

5.1 Climate Change

Research suggests that winters will become wetter over the whole of the UK, by as much as 20% by the year 2050. In making an assessment of the impact of climate change, flooding from rivers and land will give a peak flow allowance of up to 20% increase in rainfall for a given return period by 2050 and 30% by 2110. These considerations will provide an appropriate precautionary assessment for climate change impact on flood flows and rainfall intensities.

5.2 Environment Agency Flood Map

Figure 19: Environment Agency Flood Map

Proposed Development

Source: Environment Agency website (http://www.environment‐agency.gov.uk/subjects/flood)

Key

Flooding from rivers or sea without defences (Flood Zone 3)

Extent of extreme flood (Flood Zone 2)

Flood defences

Areas benefiting from flood defences

Main rivers

Report No. 13019/I/01 Project Details FRA – Residential Development at Burnley Road, Bacup Date. March 13

The Environment Agency flood zone map indicates that the site lies predominantly within Flood Zone 1, with the site access located within Flood Zone 3, being the zone comprising land as having less than the 1 in 1,000 annual probability of river or tidal/coastal flooding in any year (<0.1%).

5.3 Finished Floor Levels

Whilst the development is located primarily within a low fluvial flood zone; detailed assessment of the site indicates that there is a possibility of flooding caused via overland flow from the following sources:  Culverted unnamed watercourse in the event of hydraulic failure (See Section 4.2).  Surface water runoff from elevated ground to the west of the site.

It is therefore recommended that the internal ground floor level of the proposed dwellings are elevated a minimum of 150mm above the adjacent external finished ground level, to mitigate against any localised flooding which may be caused by heavy rainfall.

5.4 Emergency Access and Egress during Times of Flood

Access and egress from the application site is via Burnley Road; and historic flood data indicates that Burnley Road is susceptible to flooding.

It is estimated that the depth of flooding within Burnley Road during the 1 in 1000 year event could reach 0.23 metres; however with the addition of overland flows, depths of flooding may exceed this value.

Consequently dry access and egress from the development is not considered to be possible at all times.

It is therefore recommended that the property owners/occupiers sign up to receive Flood Warnings from the Environment Agency; and devise and practice a Flood Evacuation Plan; in the event that the site may become flooded.

5.5 Flood Warning

The proposed development is partially covered by the Environment Agency’s Flood Warning’s Direct Service, as shown below in Figure 19.

Due to the location of the site within close proximity to the River Irwell it is highly recommended that the residents are advised to register an interest in receiving such warnings from the Environment Agency.

This service enables the Environment Agency to send a flood warning message direct to people at home or at work by telephone, fax or pager using an Automatic Voice Messaging (AVM) Service. The aim is to give two hours' notice of flooding, either day or night, to enable people to take the necessary action to protect themselves and their properties.

Report No. 13019/I/01 Project Details FRA – Residential Development at Burnley Road, Bacup Date. March 13

The Environment Agency also provides the Floodline 0845 988 1188 service, where occupants can listen to recorded flood warning information for the area or speak to an operator for advice 24 hours a day.

Should a flood event reach the level where the development access is at risk of inundation, then the Environment Agency will issue a Severe Flood Warning.

Figure 20: Environment Agency Flood Warning Coverage Map Source: Environment Agency website (http://www.environment‐agency.gov.uk/subjects/flood)

PROPOSED DEVELOPMENT:

5.6 Evacuation Plan

For health and safety reasons there is a preference to evacuate, as failure to do so, would put the site’s residents; visitors and others (e.g. rescuers) at risk of injury.

Therefore, it is highly recommended that the a flood warning and evacuation plan from the site to a safe area away from the River Irwell is devised and practiced, should a severe flood warning be issued by the Environment Agency.

The evacuation plan should ensure that all residents, visitors and valuable possessions are relocated to a safe area above the flood water during flood conditions.

It is noted that during evacuation, all people should move towards Flood Zone 1, which lies outside of the flood plain. A footpath link to higher ground to the west could be provided by the Developer; which will allow pedestrian escape via established footpath routes towards Ash Street/Dale Street and into the town centre.

Report No. 13019/I/01 Project Details FRA – Residential Development at Burnley Road, Bacup Date. March 13

Further advice with regard to producing an effective evacuation plan can be obtained from the Environment Agency website: http://www.environment‐agency.gov.uk/homeandleisure/floods/31632.aspx

Due to the nature of proposals for the site i.e. residential, it is also recommended that the Developer undertakes liaison with Rossendale Borough Council’s Emergency Planning Team during development of the flood evacuation plan.

5.7 Culvert Diversion/Easement

The exact route of the culverted watercourse through the south part of the proposed development is currently unknown.

It is therefore recommended that a CCTV/Trace survey of the culverted watercourse is undertaken prior to the detailed design stage of the project.

The watercourse is riparian owned; however in the event that a minor diversion is required, it is likely that the Local Authority will require detailed plans of the proposed works for approval.

Furthermore in order to prevent the structural integrity of the culvert from being compromised; and provide sufficient space for inspection and maintenance purposes it is advised that a 3 metre easement either side of the culvert structure will be required.

5.8 Preliminary Drainage Strategy

5.8.1 General

Evaluation of the latest development plans provided by the Client indicates that the impermeable area attributed to roof, road and other hardstanding is increased from 0 Hectares to 0.344 Hectares. This equates to 66% of the total site area.

The preliminary drainage strategy incorporates the top ranked SUDS method resulting from the evaluation detailed within Section 4.3.4 of this report i.e. online surface water storage via large diameter pipework. The slope of the development negates the attenuation potential achievable through permeable paving solutions; and as such this method has been excluded from the preliminary drainage design. The suitability for utilising green roof technology and/or rainwater harvesting is to be determined by the Developer and Architect during the detailed design phase of the project.

The natural drainage path i.e. topography of the development; along with the drainage hierarchy set out within the Building Regulations; has determined that the discharge of surface water from the development to the culverted watercourse located along the south boundary of the site, is the most appropriate solution.

Report No. 13019/I/01 Project Details FRA – Residential Development at Burnley Road, Bacup Date. March 13

It is recommended that a review of the development layout is undertaken during the detailed design phase of the project to ensure that sufficient space is provided to accommodate the necessary pipework to achieve suitable outfalls into the culvert.

Due to the steep nature of the site, in order to prevent overly deep sewers, it is recommended that 3No outfalls to the watercourse are included within the design.

The surface water drainage modelling results indicate a total outflow from the proposed surface water drainage system of:  5.6l/s for the 1 in 1 year + 30% climate change event  11.0l/s for the 1 in 30 year + 30% climate change event  13.4l/s for the 1 in 100 year + 30% climate change event

Pro‐rated between the 3No proposed outfalls (for storms up to and including the 1 in 100 year plus 30% climate change event); or a minimum of 5l/s, whichever is the highest:  Outfall 1 – 5l/s  Outfall 2 – 5.7l/s  Outfall 3 – 5l/s

5.8.2 Attenuation Requirement

Using MicroDrainage Source Control, the following attenuation structures are considered suitable for storing surface water runoff exceeding greenfield runoff rates from the proposed residential development.

Table 7: Indicative Attenuation Details Contributing Outfall Ref Flow Control Attenuation Structure Area (Ha) 41mm diameter 51.4m of 0.8m(H) x 1.2m(W) 1 0.117 orifice plate Box culvert 44mm diameter 54.1m of 0.8m(H) x 1.5m(W) 2 0.147 orifice plate Box Culvert 42mm diameter 39.8m of 0.8m(H) x 1.2m(W) 2 0.08 orifice plate Box Culvert

5.8.3 Maintenance

Detailed design of the separate foul and surface water drainage systems will be undertaken in accordance with Sewers for Adoption 7th Edition and submitted to the Local Authority and United Utilities for adoption via a Section 104 Agreement.

5.8.4 Layout

The purpose of this report is to demonstrate that a surface water drainage strategy is feasible for the site given the development proposals and land available.

Report No. 13019/I/01 Project Details FRA – Residential Development at Burnley Road, Bacup Date. March 13

The site layout provides the opportunity for the inclusion of SUDS, ensuring that surface water runoff rates and volumes are maintained at pre‐development levels or a minimum of 5l/s whichever is the highest.

The report has been prepared to support a planning application; and as such it is highlighted that the drainage strategy presented within Appendix L of this report is indicative only; and the final decisions relating to surface water attenuation structures; rainwater harvesting and/or green roof technology will be made during the detailed design stage.

5.9 Foul Drainage

It is proposed that foul drainage from the proposed development will be directed to the public sewer system located within Burnley Road.

Report No. 13019/I/01 Project Details FRA – Residential Development at Burnley Road, Bacup Date. March 13

6.0 Conclusions and Recommendations

The development is shown to be located predominantly within Flood Zone 1 of the Environment Agency Flood Map. However the site access has been assessed to be located within Flood Zone 3.

The primary sources of flood risk to the development are identified to be from the River Irwell; a culverted unnamed tributary of the Irwell; overland flow; and an increase in surface water runoff and volume from the developed site.

Undertaking an assessment of flood risk from the River Irwell; indicates that overtopping of the banks upstream of the site is possible; with Burnley Road acting as a conveyance route, directing flood water towards Bacup town centre.

As such during flood conditions, it is likely that access and egress from the development will be compromised.

Proposals include the construction of 20No residential dwellings.

A small tributary of the River Irwell is culverted along the south boundary of the site. The exact route of the culvert is unknown at this time.

Under normal flood conditions, the capacity of the open channel upstream of the site; and the culvert are sufficient to easily convey the 1 in 100 year plus 20% climate change flow. The risk of flooding increases in the event of hydraulic failure such as blockage or collapse; when headwater upstream of the culvert is likely to become elevated above the culvert inlet.

Owing to local topography flood water overtopping from the culvert inlet is likely to be directed across the site towards Burnley Road.

A further overland flow mechanism can be attributed to the local topography. Open agricultural land is located at an elevated level immediately to the west of the site. During extreme rainfall, it is possible that the resulting surface water will be directed downhill towards then site.

I conclusion the River Irwell; unnamed watercourse and overland flow present a flood risk to the proposed development.

Recommended measures for inclusion within the development proposals to mitigate against residual flooding include the following:  Ground floor level of dwelling to be elevated 150mm above external ground levels.  Residents should be advised to sign up the Environment Agency’s Free Flood Warning’s Direct Service.  Residents should be advised to develop and practice a Flood Evacuation Plan.

Report No. 13019/I/01 Project Details FRA – Residential Development at Burnley Road, Bacup Date. March 13  Diversion to maximise development/ improve structural integrity of culverted watercourse.  Install a land drainage system along the west boundary to intercept overland flows.  Provide a flood conveyance route through the site to direct any flooding emanating from the culvert inlet.  Developer to provide a suitable pedestrian route to higher ground west of the development; to link up to existing footpaths; to provide a route to Bacup Town Centre which is located outside of the floodplain.  Culverted watercourse to have a minimum 3 metre easement either side of the barrel.

The existing site is classed as ‘greenfield’ development, and covers a gross area of 0.52 Hectares. An assessment indicates that impermeable area within the site will be increased from 0Ha to 0.344Ha following development.

Post‐development surface water runoff must be maintained at greenfield runoff rates; and flows in excess of this will need to be attenuated within the site, prior to discharge.

Disposal of surface water via infiltration is deemed unviable; and therefore it is proposed that flows will be discharged to the culverted watercourse which traverses the site.

Rainwater harvesting may be implemented in order to assist in reducing the surface water runoff volume to pre‐development values.

The Preliminary Drainage Strategy incorporates 3No outfalls to the culverted watercourse; in order to minimise the depth of the pipework over the steeply sloping site.

Report No. 13019/I/01 Project Details FRA – Residential Development at Burnley Road, Bacup Date. March 13

APPENDIX A Existing Site: Topographical Survey

Centre Notes

257.86257.98 All Dimensions to be checked on site. Walls shown on

plans are not to be assumed to be solid & should be

4 2 checked for thickness, construction, load bearing capacity BURNLEY ROAD RH266.33 & stability.

MH EH263.33 CL257.72

257.73

257.78

257.63 EH261.69 257.8m 257.70 EH263.88

257.79 DK

257.80

257.88257.95 TF259.23 EH261.08 258.19

257.60

BT 257.69

258.28 257.72

TW258.17

266.46 258.35 g 0.3 Pallisade Fence North CAR PARK 258.41

257.54 267.28

265.91 266.53 258.50 266.78 266.64 258.65 Kerb 266.91 258.71 267.06 266.75 259.99

257.58

258.06

267.32 260.15 12 257.79 267.48 GRASS 263.86 10 267.30

265.53 257.52 260.85 259.32 259.25 264.75 g 0.3 258.30

g 1.4 264.07 265.78 261.14 258.57 266.76 262.26 267.18 257.59 260.14 257.62 258.95 260.71 257.85 261.40 /GVTGU g 1.1 g 0.9 g 0.9 g 0.6 259.66 g 1.1

265.27 260.62 257.43 265.22 263.05 262.25 263.44 263.79

267.07 263.50

257.49

257.74 g 1.3 263.71 g 0.9 g 1.1

257.95

257.63

264.18 258.30

257.43 266.55 g 0.7

258.65 FENCE POSTS

g 0.6 264.03 259.23 ABBREVIATIONS

257.52

267.11 267.18 260.00 257.68 268.35 CL Cover Level

RH265.15 TW268.26 257.49 DK Drop Kerb 261.07 LP GU GU EH Eaves Height g 0.6 EH262.21

267.92 268.91 261.92 FH Fire Hydrant GU Gulley 262.67 FH 266.44 LP Lamp Post

257.53 257.35 257.31 MH Man Hole 264.04 267.92 g 0.8

268.80

257.56 RH Ridge Height

267.10 Kerb 257.80 TF Top of Fence 257.32 g 0.8 Kerb Telegraph Pole g 0.9 258.11 TP

TARMAC

TARMAC 270.00 TW Top of Wall g 0.5 WV Water Valve g 1.6 258.44 Kerb

257.41

g 0.9 263.99 259.13 257.51 g Tree Girth

269.63 263.51

260.07

g 0.6

24 261.03 257.38 22 261.69 MH

257.41 CL257.26 262.44 NOTE g 0.6 All levels relate to OSGB36 Coordinates using GNSS data.

257.25

269.28

257.41

257.70 257.20 Levels defining edge of carriageway are observed at channel (bottom of kerb).

263.93 GRASS 258.00

263.32 257.19 258.32 g 1.3 g 1.3

257.31 259.23

g 1.2 257.42

269.03 260.19 264.15

267.33 266.22 BT GU 261.11 257.23

g 0.9 257.32

257.08 261.62

g 0.6

g 0.9 262.39 257.40

257.58

263.00 257.93 g 1.3 GAS 266.06 264.12 267.42 GAS GRASS 258.18 257.07 257.25 g 1.2 257.19 257.10 g 1.3 259.33 WV 259.81

260.42

257.16 GAS 267.26 261.12 257.66 257.40 g 0.6 262.97 258.12 266.13 264.58 261.70 EH260.58 STREET 258.15 257.36 LAUREL

g 1.1 257.20

256.99 262.36 TW257.34 MH 258.11 CL256.93 Gas Govn 258.02 257.88 g 1.2 263.07 258.06 257.90 MH CONCRETE CL256.93 258.61 TW258.84 257.14

257.06

TW259.13 256.90 258.11 263.89 259.59 MH 260.09 CL258.15 257.83 264.47 260.60 265.90 258.10 g 1.2 TW259.27

266.75 263.43 261.24 258.49

261.61 EH263.39 g 0.9 258.75 78 264.41 g 1.0 265.42 262.79 g 0.6 Rev.0 Description. Issued 259.31 RH266.40 266.56 262.14

260.23 EH265.62 262.33 TP 261.06 g 1.6 g 0.9 260.82 266.53 SHRUBS RH267.95 10

265.80

TW262.32 EH265.57

263.63 g 1.3 261.25 266.95 Post & Rail Fence 266.97 Scout 261.57 262.48

g 1.3 TW262.56 261.58 EH266.03

264.32 261.93 HQ Site Address RH268.12

3 263.33 261.81 Burnley Road 262.65 TW262.77 TW266.42 TW263.30 Bacup 262.30

TW263.56

Project Description 1 Existing Site Survey STREET

68 STREET

EH267.27 Drawing Title 2 ST JOHN

EH271.58 BACK ST JOHN Site Survey

RH269.14 2

RH273.43 12 Scale Date Drawn By 22 256.3m 1:200@A1 28/01/2013 AD Drawing Number TERRACE TRI-0973-01 ALBERT 7KHFRQWHQWVRIWKLVGUDZLQJDQGHQWLWLHVXVHGDUHFRS\ULJKW7UL&$'6ROXWLRQV/WG Report No. 13019/I/01 Project Details FRA – Residential Development at Burnley Road, Bacup Date. March 13

APPENDIX B Proposed Development Plan

All dimensions to be as noted. Do not scale from this drawing. Report any discrepancies R to the Architect / CA immediately. All Areas are approximate and use of these Areas for commercial purposes should include due allowance for variations inherent in design development and building processes. This drawing is the copyright and property of B Hurd Rolland Partnership and must not be reproduced without prior written permission

A Rev Description By Chk Date

N - Initial Issue KHW IG 11.02.13

A Minor updates following Civil Engineer's comments KHW IG 05.03.13 K B Turning heads added. Semi-buried gas meter boxes KHW SD 19.03.13

indicated and footpaths adjusted to suit. Retaining

3 wall indicated to western boundary. 1

LB Sta Sub El C

Leisure L Centre O S

4 2 281.4m B

257.8m N

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+ PLANNING NOTES:

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6 1. Please read in conjunction with application drawings, documents and

L other supporting information.

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+ 2. Proposals are subject to Building Regulations approval.

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. 3. Landscape proposals indicative only and subject to detail design

2 o

+ approved under condition (by others).

l 8

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ST 4. All construction section/ details are indicative only and subject to 2

r 5 0 LAUREL

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d 5. Drawings based on existing measured data provided by TriCAD

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a 7 Solutions Ltd, 28th January 2013. e

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n 5 6. All party wall and ROL matters are subject to agreement.

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L 7. Boundary treatments are subject to ALO approval.

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l 8. External lighting is subject to detail design approved under condition

. S

. (by others).

S 5

S LEGEND:

S o

l 7

P 0 Permeable block paving to parking areas.

5 1 Soft landscaping. 0

Scout Raised block paving traffic calming to access road HQ N Proposed trees.

1 H T (Existing trees to be retained where possible). 8

5 O E l 423300 0 T J Indicative garden shed N E

0 e E T R H Indicative rotary washing line 1 w E T S

r O Site Boundary

S I R J K N

r House plot boundary

8 T C T

6 e S

A Sinks 2 S s v t c B e

Project t i i h c r d Rossendale A

R 2 Land Adjacent to Bacup Leisure Centre n BURNLEY ROAD, BACUP a l

12 Weir l 22 256.3m for RTB Partnership Valley o r Title p i h s

E r C e d n

A t r

R PROPOSED SITE PLAN a

R P

E r T d n a l l RT o R

B u d AL r u

Drawn:KHW Checked:GTC Approved: H C Scale: 1:500@A3 Date:11.02.2013 Project No:M7591 h 7th Floor Drawing No: Revision: 44 Peter Street Manchester M2 5GP

L(01)10 B Tel: 0161 832 5322

Fax: 0161 832 5245

1 1

1 9 1 Alderside Mill ISSUED FORINFORMATION Report No. 13019/I/01 Project Details FRA – Residential Development at Burnley Road, Bacup Date. March 13

APPENDIX C Environment Agency Flood Level Data

PROTECT_WAR7032 Response attached Page 1 of 2

From: NW South, External Relations ([email protected]) To: '[email protected]' ([email protected]) Date: Mar 15, 2013 15:35 Subject: PROTECT_WAR7032 Response attached

Attachments: Final Table.pdf PRRWAR7032 - HISTORICAL.PDF PRRWAR7032.pdf Development guidance.pdf STANDARD NOTICE.pdf

Our Ref: WAR7032 Date: 15/3/13

Dear Donna,

PUBLIC REGISTER AND ENVIRONMENTAL INFORMATION REQUEST Burnley Road, Bacup

Thank you for your email regarding the above site. Requests for recorded information are generally governed by the Freedom of Information Act 2000 (FOIA).The information you have requested is environmental and is therefore exempt from the provisions of FOIA by FOIA s.39(1). We have therefore considered your request under the Environmental Information Regulations 2004 (EIR). Please find our response below.

Please find the product 4 data attached as requested.

Rights of appeal

We hope that our response has addressed all of the questions that you have asked. However, if you are not satisfied with our response to your request for information, you can contact us to ask for our decision to be reviewed. If you are still not satisfied following this, you can make an appeal to the Information Commissioner, who is the statutory regulator for Freedom of Information. Their contact details are: Office of the Information Commissioner, Wycliffe House, Water Lane, Wilmslow, Cheshire SK9 5AF .

Tel: 01625 545700. Fax: 01625 524 510

email: [email protected].

Website: http//www.ico.gov.uk We would be really grateful if you could spare five minutes to help us improve our service. Please click on the link below and fill in our survey – we use every piece of feedback we receive: http://www.surveyshack.com/link/d5ea8 Yours sincerely,

Anne

Anne Ball Customer Services Officer Direct dial: 01925 54 2937

E-mail: [email protected]

https://webmail.one.com/email/?get=msg&xslt=print&intent=print&inline&sp&folder... 20/03/2013 Detailed map centred on Site near River Irwell, Bacup . Created on 14th March 2013 [Ref. PRRWAR7032]

Scale 1:10,000 ¯

Legend I R

E )" Model_measurements L K O L O R B ^ Site location H G U O L Historic Flood Event Outline C ")1 E V A Main River ")2 E R G Flood Zone 3 ^")3 Flood Zone 2 ")4

© Environment Agency copyright and / or database rights 2013. All rights reserved. © Crown Copyright and database right. All rights reserved. Environment Agency, 100026380, 2013. Contact Us: National Customer Contact Centre, PO Box 544, Rotherham, S60 1BY. Tel: 08708 506 506 (Mon-Fri 8-6). Email: [email protected] Historic Flood Event Outline map centred near River Irwell, Bacup . Created on 14th March 2013 [Ref. PRRWAR7032]

Scale 1:5,000 ¯

")1

")2 Legend )" Model_measurements ^ Site location Historic Flood Event Outline ^ Main River ")3

")4

I R K W O O E R L B H L G U LO C E V EA R G

ea013_0140

Map Reference Model Node Reference Easting Northing Data 10 % AEP (1 in 10 year) 5 % AEP (1 in 20 year) 1.33 % AEP (1 in 75 year) 1 % AEP (1 in 100 year) 0.1 % AEP (1 in 1000 year)

Modelled Water Level (m aod) 257.8 257.91 258.22 258.32 259.46 1 ea0140IRWE09_2938d 386700 423518 Modelled Flow (cumecs) 7.46 8.28 9.92 10.28 17.24

Modelled Water Level (m aod) 257.56 257.69 258.08 258.19 259.43 2 ea0140IRWE09_2894u 386714 423473 Modelled Flow (cumecs) 7.46 8.27 9.92 10.28 13.03

Modelled Water Level (m aod) 255.52 255.59 255.71 255.74 256.22 3 ea0140IRWE09_2732d 386746 423322 Modelled Flow (cumecs) 7.46 8.27 9.91 10.27 13.05

Modelled Water Level (m aod) 255.4 255.46 255.58 255.6 255.98 4 ea0140IRWE09_2700u 386743 423285 Modelled Flow (cumecs) 7.45 8.27 9.91 10.26 16.3

Model data taken from The River Irwell and Limy Water Study 2011 Historical Flood Event Outline Attributes

Notes: Flood Event Code Name Start Date End Date Source of Flooding Cause of Flooding

AEP - Annual Exceedence Probability 209 IRWE 14/06/2002 15/06/2002 Unknown Channel capacity exceeded m aod - metres above ordnance datum cumecs - cubic metres per second Report No. 13019/I/01 Project Details FRA – Residential Development at Burnley Road, Bacup Date. March 13

APPENDIX D IOH124 River Flow Calculation

Paul Waite Associates Page 1 Summit House Burnely Road, Bacup Riparian Way Unnaamed Watercourse Keighley BD20 7BW Flows Date 22 March 2013 Designed By DM File Checked By Infrasoft Source Control W.12.4

ICP SUDS Mean Annual Flood

Input

Return Period (years) 1 Soil 0.500 Area (ha) 8.700 Urban 0.000 SAAR (mm) 1400 Region Number Region 10

Results l/s

QBAR Rural 108.1 QBAR Urban 108.1

Q1 year 94.0

Q1 year 94.0 Q30 years 183.3 Q100 years 224.8

APPENDIX E IOH124 Existing Greenfield Runoff

Paul Waite Associates Page 1 Summit House Burnley Road, Bacup Riparian Way Greenfield Runoff Keighley BD20 7BW 50 Hectares Date 22 March 2013 Designed By DM File Checked By Infrasoft Source Control W.12.4

IH 124 Mean Annual Flood

Input

Return Period (years) 1 Soil 0.500 Area (ha) 50.000 Urban 0.000 SAAR (mm) 1400 Region Number Region 10

Results l/s

QBAR Rural 621.2 QBAR Urban 621.2

Q1 year 540.5

Q1 year 540.5 Q2 years 578.6 Q5 years 739.2 Q10 years 857.3 Q20 years 976.7 Q25 years 1018.8 Q30 years 1053.2 Q50 years 1149.2 Q100 years 1292.1 Q200 years 1466.1 Q250 years 1522.0 Q1000 years 1888.5

APPENDIX F Historic Borehole Logs & Soilscape Map

Page 1 | Borehole SD82SE13 | Borehole Logs Page 2 of 2

http://scans.bgs.ac.uk/sobi_scans/boreholes/30898/images/10043899.html 24/03/2013 Page 2 | Borehole SD82SE65 | Borehole Logs Page 2 of 2

http://scans.bgs.ac.uk/sobi_scans/boreholes/30950/images/10043938.html 24/03/2013 Page 1 | Borehole SD82SE47 | Borehole Logs Page 2 of 2

http://scans.bgs.ac.uk/sobi_scans/boreholes/30932/images/10043937.html 24/03/2013

Report No. 13019/I/01 Project Details FRA – Residential Development at Burnley Road, Bacup Date. March 13

APPENDIX G SUDS Planner

Paul Waite Associates Page 6 Summit House Riparian Way Keighley BD20 7BW Date 25/03/2013 08:35 Designed By Donna Metcalf File outfall 1.srcx Checked By Infrasoft Source Control W.12.4

SUDS Planner

Results

Ordered By Total

Quick Rank Hydrological Land Use Site Total Community Economics View Features and and Environment Maintenance

Online / Offline Storage (1, 4, 8) 18 (10th) 38 (1st) 36 (2nd) 92 (1st) 22 (4th) 20 (8th) Green Roofs (2, 7, 2) 26 (2nd) 20 (12th) 40 (1st) 86 (2nd) 20 (7th) 24 (2nd) Pervious Pavements (2, 7, 5) 28 (1st) 28 (3rd) 30 (4th) 86 (2nd) 20 (7th) 22 (5th) Filtration Techniques (4, 7, 13) 16 (12th) 30 (2nd) 34 (3rd) 80 (4th) 20 (7th) 14 (13th) Infiltration Trench / Soakaway (5, 10, 8) 24 (3rd) 28 (3rd) 24 (8th) 76 (5th) 18 (10th) 20 (8th) Filter Drains (6, 10, 11) 20 (8th) 28 (3rd) 26 (5th) 74 (6th) 18 (10th) 18 (11th) Grassed Swales (7, 4, 5) 22 (6th) 26 (10th) 24 (8th) 72 (7th) 22 (4th) 22 (5th) Bioretention Area (7, 1, 11) 18 (10th) 28 (3rd) 26 (5th) 72 (7th) 26 (1st) 18 (11th) Dry Detention (9, 10, 2) 20 (8th) 28 (3rd) 16 (11th) 64 (9th) 18 (10th) 24 (2nd) Wet Ponds (9, 4, 1) 24 (3rd) 28 (3rd) 12 (13th) 64 (9th) 22 (4th) 26 (1st) Stormwater Wetlands (9, 2, 5) 22 (6th) 28 (3rd) 14 (12th) 64 (9th) 24 (2nd) 22 (5th) Infiltration Basin (9, 13, 8) 24 (3rd) 20 (12th) 20 (10th) 64 (9th) 16 (13th) 20 (8th) Grassed Filter Strip (13, 2, 2) 12 (13th) 24 (11th) 26 (5th) 62 (13th) 24 (2nd) 24 (2nd)

APPENDIX H Catchment Area Plan

Report No. 13019/I/01 Project Details FRA – Residential Development at Burnley Road, Bacup Date. March 13

APPENDIX I Attenuation Calculations Outfall 1

Paul Waite Associates Page 1 Summit House Burnley Road, Bacup Riparian Way Outfall 1 Keighley BD20 7BW 1 in 1yr + 30%CC Date 25/03/13 Designed By Donna Metcalf File outfall 1.srcx Checked By Infrasoft Source Control W.12.4

Summary of Results for 1 year Return Period (+30%)

Storm Max Max Max Max Status Event Level Depth Control Volume (m) (m) (l/s) (m³)

15 min Summer 259.788 0.188 1.4 6.2 O K 30 min Summer 259.818 0.218 1.6 8.0 O K 60 min Summer 259.845 0.245 1.7 9.6 O K 120 min Summer 259.868 0.268 1.7 11.1 O K 180 min Summer 259.878 0.278 1.8 11.7 O K 240 min Summer 259.881 0.281 1.8 11.9 O K 360 min Summer 259.879 0.279 1.8 11.7 O K 480 min Summer 259.874 0.274 1.8 11.4 O K 600 min Summer 259.867 0.267 1.7 11.0 O K 720 min Summer 259.860 0.260 1.7 10.6 O K 960 min Summer 259.845 0.245 1.7 9.6 O K 1440 min Summer 259.817 0.217 1.6 7.9 O K 2160 min Summer 259.785 0.185 1.4 6.0 O K 2880 min Summer 259.761 0.161 1.3 4.6 O K 4320 min Summer 259.726 0.126 1.1 2.8 O K 5760 min Summer 259.703 0.103 1.0 1.9 O K 7200 min Summer 259.686 0.086 0.9 1.3 O K 8640 min Summer 259.673 0.073 0.8 1.0 O K 10080 min Summer 259.664 0.064 0.7 0.7 O K

Storm Rain Time-Peak Event (mm/hr) (mins)

15 min Summer 32.700 17 30 min Summer 22.858 31 60 min Summer 15.709 52 120 min Summer 10.691 86 180 min Summer 8.523 122 240 min Summer 7.209 156 360 min Summer 5.673 226 480 min Summer 4.788 292 600 min Summer 4.200 358 720 min Summer 3.775 424 960 min Summer 3.186 550 1440 min Summer 2.509 796 2160 min Summer 1.981 1164 2880 min Summer 1.668 1524 4320 min Summer 1.306 2244 5760 min Summer 1.095 2944 7200 min Summer 0.950 3672 8640 min Summer 0.846 4400 10080 min Summer 0.766 5136

©1982-2010 Micro Drainage Ltd Paul Waite Associates Page 2 Summit House Burnley Road, Bacup Riparian Way Outfall 1 Keighley BD20 7BW 1 in 1yr + 30%CC Date 25/03/13 Designed By Donna Metcalf File outfall 1.srcx Checked By Infrasoft Source Control W.12.4

Summary of Results for 1 year Return Period (+30%)

Storm Max Max Max Max Status Event Level Depth Control Volume (m) (m) (l/s) (m³)

15 min Winter 259.802 0.202 1.5 7.0 O K 30 min Winter 259.837 0.237 1.6 9.1 O K 60 min Winter 259.868 0.268 1.7 11.1 O K 120 min Winter 259.893 0.293 1.8 12.6 O K 180 min Winter 259.902 0.302 1.9 13.2 O K 240 min Winter 259.902 0.302 1.9 13.2 O K 360 min Winter 259.892 0.292 1.8 12.6 O K 480 min Winter 259.880 0.280 1.8 11.8 O K 600 min Winter 259.866 0.266 1.7 11.0 O K 720 min Winter 259.853 0.253 1.7 10.2 O K 960 min Winter 259.829 0.229 1.6 8.6 O K 1440 min Winter 259.789 0.189 1.4 6.2 O K 2160 min Winter 259.748 0.148 1.3 3.9 O K 2880 min Winter 259.720 0.120 1.1 2.5 O K 4320 min Winter 259.685 0.085 0.9 1.3 O K 5760 min Winter 259.667 0.067 0.8 0.8 O K 7200 min Winter 259.657 0.057 0.7 0.6 O K 8640 min Winter 259.652 0.052 0.6 0.5 O K 10080 min Winter 259.649 0.049 0.5 0.4 O K

Storm Rain Time-Peak Event (mm/hr) (mins)

15 min Winter 32.700 17 30 min Winter 22.858 31 60 min Winter 15.709 58 120 min Winter 10.691 92 180 min Winter 8.523 132 240 min Winter 7.209 170 360 min Winter 5.673 242 480 min Winter 4.788 312 600 min Winter 4.200 380 720 min Winter 3.775 448 960 min Winter 3.186 578 1440 min Winter 2.509 824 2160 min Winter 1.981 1188 2880 min Winter 1.668 1528 4320 min Winter 1.306 2208 5760 min Winter 1.095 2936 7200 min Winter 0.950 3672 8640 min Winter 0.846 4400 10080 min Winter 0.766 5072

©1982-2010 Micro Drainage Ltd Paul Waite Associates Page 1 Summit House Burnley Road, Bacup Riparian Way Outfall 1 Keighley BD20 7BW 1 in 30yr + 30%CC Date 25/03/13 Designed By Donna Metcalf File outfall 1.srcx Checked By Infrasoft Source Control W.12.4

Summary of Results for 30 year Return Period (+30%)

Storm Max Max Max Max Status Event Level Depth Control Volume (m) (m) (l/s) (m³)

15 min Summer 259.948 0.348 2.0 16.0 O K 30 min Summer 260.037 0.437 2.3 21.6 O K 60 min Summer 260.122 0.522 2.5 27.0 O K 120 min Summer 260.184 0.584 2.6 30.8 O K 180 min Summer 260.206 0.606 2.7 32.2 O K 240 min Summer 260.214 0.614 2.7 32.7 O K 360 min Summer 260.214 0.614 2.7 32.7 O K 480 min Summer 260.203 0.603 2.7 32.0 O K 600 min Summer 260.188 0.588 2.6 31.1 O K 720 min Summer 260.172 0.572 2.6 30.1 O K 960 min Summer 260.138 0.538 2.5 28.0 O K 1440 min Summer 260.075 0.475 2.4 24.0 O K 2160 min Summer 259.998 0.398 2.2 19.2 O K 2880 min Summer 259.939 0.339 2.0 15.5 O K 4320 min Summer 259.858 0.258 1.7 10.5 O K 5760 min Summer 259.807 0.207 1.5 7.3 O K 7200 min Summer 259.771 0.171 1.4 5.2 O K 8640 min Summer 259.748 0.148 1.3 3.9 O K 10080 min Summer 259.729 0.129 1.2 2.9 O K

Storm Rain Time-Peak Event (mm/hr) (mins)

15 min Summer 79.865 18 30 min Summer 56.172 32 60 min Summer 38.009 60 120 min Summer 24.918 100 180 min Summer 19.161 134 240 min Summer 15.849 168 360 min Summer 12.112 238 480 min Summer 9.991 306 600 min Summer 8.597 376 720 min Summer 7.599 442 960 min Summer 6.248 576 1440 min Summer 4.731 836 2160 min Summer 3.574 1208 2880 min Summer 2.930 1560 4320 min Summer 2.216 2292 5760 min Summer 1.819 3000 7200 min Summer 1.562 3744 8640 min Summer 1.381 4408 10080 min Summer 1.245 5144

©1982-2010 Micro Drainage Ltd Paul Waite Associates Page 2 Summit House Burnley Road, Bacup Riparian Way Outfall 1 Keighley BD20 7BW 1 in 30yr + 30%CC Date 25/03/13 Designed By Donna Metcalf File outfall 1.srcx Checked By Infrasoft Source Control W.12.4

Summary of Results for 30 year Return Period (+30%)

Storm Max Max Max Max Status Event Level Depth Control Volume (m) (m) (l/s) (m³)

15 min Winter 259.981 0.381 2.1 18.1 O K 30 min Winter 260.083 0.483 2.4 24.5 O K 60 min Winter 260.184 0.584 2.6 30.8 O K 120 min Winter 260.257 0.657 2.8 35.4 O K 180 min Winter 260.280 0.680 2.9 36.8 O K 240 min Winter 260.287 0.687 2.9 37.3 O K 360 min Winter 260.278 0.678 2.8 36.7 O K 480 min Winter 260.255 0.655 2.8 35.3 O K 600 min Winter 260.227 0.627 2.7 33.5 O K 720 min Winter 260.199 0.599 2.7 31.8 O K 960 min Winter 260.144 0.544 2.5 28.3 O K 1440 min Winter 260.050 0.450 2.3 22.5 O K 2160 min Winter 259.946 0.346 2.0 15.9 O K 2880 min Winter 259.875 0.275 1.8 11.5 O K 4320 min Winter 259.790 0.190 1.4 6.3 O K 5760 min Winter 259.742 0.142 1.2 3.6 O K 7200 min Winter 259.713 0.113 1.1 2.2 O K 8640 min Winter 259.694 0.094 0.9 1.5 O K 10080 min Winter 259.680 0.080 0.9 1.1 O K

Storm Rain Time-Peak Event (mm/hr) (mins)

15 min Winter 79.865 18 30 min Winter 56.172 32 60 min Winter 38.009 60 120 min Winter 24.918 112 180 min Winter 19.161 142 240 min Winter 15.849 180 360 min Winter 12.112 256 480 min Winter 9.991 332 600 min Winter 8.597 404 720 min Winter 7.599 474 960 min Winter 6.248 610 1440 min Winter 4.731 868 2160 min Winter 3.574 1252 2880 min Winter 2.930 1612 4320 min Winter 2.216 2332 5760 min Winter 1.819 3000 7200 min Winter 1.562 3680 8640 min Winter 1.381 4408 10080 min Winter 1.245 5136

©1982-2010 Micro Drainage Ltd Paul Waite Associates Page 1 Summit House Burnley Road, Bacup Riparian Way Outfall 1 Keighley BD20 7BW 1 in 100yr + 30%CC Date 25/03/13 Designed By Donna Metcalf File outfall 1.srcx Checked By Infrasoft Source Control W.12.4

Summary of Results for 100 year Return Period (+30%)

Storm Max Max Max Max Status Event Level Depth Control Volume (m) (m) (l/s) (m³)

15 min Summer 260.026 0.426 2.2 20.9 O K 30 min Summer 260.150 0.550 2.6 28.7 O K 60 min Summer 260.276 0.676 2.8 36.6 O K 120 min Summer 260.370 0.770 3.0 42.4 O K 180 min Summer 260.401 0.801 3.1 44.2 O K 240 min Summer 260.413 0.813 3.1 44.9 O K 360 min Summer 260.414 0.814 3.1 44.9 O K 480 min Summer 260.399 0.799 3.1 44.1 O K 600 min Summer 260.378 0.778 3.1 42.8 O K 720 min Summer 260.355 0.755 3.0 41.5 O K 960 min Summer 260.309 0.709 2.9 38.6 O K 1440 min Summer 260.224 0.624 2.7 33.4 O K 2160 min Summer 260.120 0.520 2.5 26.8 O K 2880 min Summer 260.041 0.441 2.3 21.9 O K 4320 min Summer 259.933 0.333 2.0 15.1 O K 5760 min Summer 259.864 0.264 1.7 10.8 O K 7200 min Summer 259.818 0.218 1.6 8.0 O K 8640 min Summer 259.784 0.184 1.4 5.9 O K 10080 min Summer 259.761 0.161 1.3 4.6 O K

Storm Rain Time-Peak Event (mm/hr) (mins)

15 min Summer 102.866 18 30 min Summer 73.221 32 60 min Summer 49.937 62 120 min Summer 32.721 108 180 min Summer 24.983 140 240 min Summer 20.537 172 360 min Summer 15.556 242 480 min Summer 12.742 312 600 min Summer 10.901 380 720 min Summer 9.587 448 960 min Summer 7.817 580 1440 min Summer 5.843 838 2160 min Summer 4.351 1212 2880 min Summer 3.532 1584 4320 min Summer 2.636 2296 5760 min Summer 2.144 3008 7200 min Summer 1.829 3744 8640 min Summer 1.609 4416 10080 min Summer 1.446 5144

©1982-2010 Micro Drainage Ltd Paul Waite Associates Page 2 Summit House Burnley Road, Bacup Riparian Way Outfall 1 Keighley BD20 7BW 1 in 100yr + 30%CC Date 25/03/13 Designed By Donna Metcalf File outfall 1.srcx Checked By Infrasoft Source Control W.12.4

Summary of Results for 100 year Return Period (+30%)

Storm Max Max Max Max Status Event Level Depth Control Volume (m) (m) (l/s) (m³)

15 min Winter 260.068 0.468 2.3 23.6 O K 30 min Winter 260.210 0.610 2.7 32.5 O K 60 min Winter 260.358 0.758 3.0 41.7 O K 120 min Winter 260.539 0.939 3.4 48.6 O K 180 min Winter 261.377 1.777 4.6 49.5 Flood Risk 240 min Winter 261.600 2.000 4.9 49.8 Flood Risk 360 min Winter 261.290 1.690 4.5 49.4 O K 480 min Winter 260.627 1.027 3.5 48.8 O K 600 min Winter 260.457 0.857 3.2 46.8 O K 720 min Winter 260.407 0.807 3.1 44.5 O K 960 min Winter 260.332 0.732 3.0 40.0 O K 1440 min Winter 260.206 0.606 2.7 32.2 O K 2160 min Winter 260.065 0.465 2.3 23.4 O K 2880 min Winter 259.969 0.369 2.1 17.3 O K 4320 min Winter 259.850 0.250 1.7 10.0 O K 5760 min Winter 259.785 0.185 1.4 6.0 O K 7200 min Winter 259.745 0.145 1.2 3.7 O K 8640 min Winter 259.719 0.119 1.1 2.5 O K 10080 min Winter 259.701 0.101 1.0 1.8 O K

Storm Rain Time-Peak Event (mm/hr) (mins)

15 min Winter 102.866 18 30 min Winter 73.221 32 60 min Winter 49.937 60 120 min Winter 32.721 114 180 min Winter 24.983 134 240 min Winter 20.537 172 360 min Winter 15.556 248 480 min Winter 12.742 332 600 min Winter 10.901 410 720 min Winter 9.587 482 960 min Winter 7.817 620 1440 min Winter 5.843 884 2160 min Winter 4.351 1272 2880 min Winter 3.532 1640 4320 min Winter 2.636 2336 5760 min Winter 2.144 3056 7200 min Winter 1.829 3744 8640 min Winter 1.609 4408 10080 min Winter 1.446 5144

APPENDIX J Attenuation Calculations Outfall 2

Paul Waite Associates Page 1 Summit House Burnley Road, Bacup Riparian Way Outfall 2 Keighley BD20 7BW 1 in 1yr + 30%CC Date 25/03/13 Designed By Donna Metcalf File outfall 2.srcx Checked By Infrasoft Source Control W.12.4

Summary of Results for 1 year Return Period (+30%)

Storm Max Max Max Max Status Event Level Depth Control Volume (m) (m) (l/s) (m³)

15 min Summer 257.183 0.183 1.6 7.9 O K 30 min Summer 257.214 0.214 1.8 10.3 O K 60 min Summer 257.241 0.241 1.9 12.5 O K 120 min Summer 257.266 0.266 2.0 14.5 O K 180 min Summer 257.278 0.278 2.0 15.5 O K 240 min Summer 257.282 0.282 2.1 15.8 O K 360 min Summer 257.282 0.282 2.1 15.9 O K 480 min Summer 257.279 0.279 2.0 15.6 O K 600 min Summer 257.274 0.274 2.0 15.2 O K 720 min Summer 257.268 0.268 2.0 14.7 O K 960 min Summer 257.255 0.255 1.9 13.6 O K 1440 min Summer 257.230 0.230 1.8 11.6 O K 2160 min Summer 257.199 0.199 1.7 9.1 O K 2880 min Summer 257.174 0.174 1.6 7.2 O K 4320 min Summer 257.139 0.139 1.4 4.6 O K 5760 min Summer 257.115 0.115 1.2 3.1 O K 7200 min Summer 257.097 0.097 1.1 2.2 O K 8640 min Summer 257.084 0.084 1.0 1.7 O K 10080 min Summer 257.074 0.074 0.9 1.3 O K

Storm Rain Time-Peak Event (mm/hr) (mins)

15 min Summer 32.700 17 30 min Summer 22.858 31 60 min Summer 15.709 54 120 min Summer 10.691 88 180 min Summer 8.523 124 240 min Summer 7.209 158 360 min Summer 5.673 228 480 min Summer 4.788 296 600 min Summer 4.200 362 720 min Summer 3.775 428 960 min Summer 3.186 558 1440 min Summer 2.509 808 2160 min Summer 1.981 1172 2880 min Summer 1.668 1528 4320 min Summer 1.306 2248 5760 min Summer 1.095 2944 7200 min Summer 0.950 3672 8640 min Summer 0.846 4408 10080 min Summer 0.766 5136

©1982-2010 Micro Drainage Ltd Paul Waite Associates Page 2 Summit House Burnley Road, Bacup Riparian Way Outfall 2 Keighley BD20 7BW 1 in 1yr + 30%CC Date 25/03/13 Designed By Donna Metcalf File outfall 2.srcx Checked By Infrasoft Source Control W.12.4

Summary of Results for 1 year Return Period (+30%)

Storm Max Max Max Max Status Event Level Depth Control Volume (m) (m) (l/s) (m³)

15 min Winter 257.196 0.196 1.7 8.9 O K 30 min Winter 257.232 0.232 1.9 11.7 O K 60 min Winter 257.265 0.265 2.0 14.4 O K 120 min Winter 257.292 0.292 2.1 16.6 O K 180 min Winter 257.303 0.303 2.1 17.6 O K 240 min Winter 257.305 0.305 2.2 17.7 O K 360 min Winter 257.299 0.299 2.1 17.2 O K 480 min Winter 257.289 0.289 2.1 16.4 O K 600 min Winter 257.278 0.278 2.0 15.5 O K 720 min Winter 257.266 0.266 2.0 14.5 O K 960 min Winter 257.244 0.244 1.9 12.7 O K 1440 min Winter 257.205 0.205 1.7 9.6 O K 2160 min Winter 257.164 0.164 1.5 6.4 O K 2880 min Winter 257.135 0.135 1.4 4.3 O K 4320 min Winter 257.098 0.098 1.1 2.2 O K 5760 min Winter 257.077 0.077 0.9 1.4 O K 7200 min Winter 257.064 0.064 0.8 1.0 O K 8640 min Winter 257.058 0.058 0.7 0.8 O K 10080 min Winter 257.055 0.055 0.7 0.7 O K

Storm Rain Time-Peak Event (mm/hr) (mins)

15 min Winter 32.700 17 30 min Winter 22.858 31 60 min Winter 15.709 58 120 min Winter 10.691 94 180 min Winter 8.523 134 240 min Winter 7.209 172 360 min Winter 5.673 246 480 min Winter 4.788 318 600 min Winter 4.200 386 720 min Winter 3.775 456 960 min Winter 3.186 588 1440 min Winter 2.509 838 2160 min Winter 1.981 1208 2880 min Winter 1.668 1556 4320 min Winter 1.306 2248 5760 min Winter 1.095 2936 7200 min Winter 0.950 3648 8640 min Winter 0.846 4320 10080 min Winter 0.766 5072

©1982-2010 Micro Drainage Ltd Paul Waite Associates Page 1 Summit House Burnley Road, Bacup Riparian Way Outfall 2 Keighley BD20 7BW 1 in 30yr + 30%CC Date 25/03/13 Designed By Donna Metcalf File outfall 2.srcx Checked By Infrasoft Source Control W.12.4

Summary of Results for 30 year Return Period (+30%)

Storm Max Max Max Max Status Event Level Depth Control Volume (m) (m) (l/s) (m³)

15 min Summer 257.337 0.337 2.3 20.4 O K 30 min Summer 257.425 0.425 2.6 27.5 O K 60 min Summer 257.511 0.511 2.8 34.7 O K 120 min Summer 257.576 0.576 3.0 40.0 O K 180 min Summer 257.600 0.600 3.1 41.9 O K 240 min Summer 257.611 0.611 3.1 42.8 O K 360 min Summer 257.616 0.616 3.1 43.2 O K 480 min Summer 257.609 0.609 3.1 42.6 O K 600 min Summer 257.597 0.597 3.1 41.7 O K 720 min Summer 257.583 0.583 3.0 40.5 O K 960 min Summer 257.554 0.554 2.9 38.1 O K 1440 min Summer 257.496 0.496 2.8 33.4 O K 2160 min Summer 257.423 0.423 2.6 27.4 O K 2880 min Summer 257.365 0.365 2.4 22.6 O K 4320 min Summer 257.283 0.283 2.1 15.9 O K 5760 min Summer 257.229 0.229 1.8 11.5 O K 7200 min Summer 257.192 0.192 1.7 8.6 O K 8640 min Summer 257.165 0.165 1.5 6.5 O K 10080 min Summer 257.146 0.146 1.4 5.0 O K

Storm Rain Time-Peak Event (mm/hr) (mins)

15 min Summer 79.865 18 30 min Summer 56.172 32 60 min Summer 38.009 62 120 min Summer 24.918 106 180 min Summer 19.161 138 240 min Summer 15.849 172 360 min Summer 12.112 242 480 min Summer 9.991 310 600 min Summer 8.597 380 720 min Summer 7.599 448 960 min Summer 6.248 580 1440 min Summer 4.731 838 2160 min Summer 3.574 1212 2880 min Summer 2.930 1584 4320 min Summer 2.216 2296 5760 min Summer 1.819 3008 7200 min Summer 1.562 3744 8640 min Summer 1.381 4416 10080 min Summer 1.245 5144

©1982-2010 Micro Drainage Ltd Paul Waite Associates Page 2 Summit House Burnley Road, Bacup Riparian Way Outfall 2 Keighley BD20 7BW 1 in 30yr + 30%CC Date 25/03/13 Designed By Donna Metcalf File outfall 2.srcx Checked By Infrasoft Source Control W.12.4

Summary of Results for 30 year Return Period (+30%)

Storm Max Max Max Max Status Event Level Depth Control Volume (m) (m) (l/s) (m³)

15 min Winter 257.369 0.369 2.4 22.9 O K 30 min Winter 257.469 0.469 2.7 31.2 O K 60 min Winter 257.571 0.571 3.0 39.5 O K 120 min Winter 257.650 0.650 3.2 46.0 O K 180 min Winter 257.674 0.674 3.3 48.0 O K 240 min Winter 257.685 0.685 3.3 48.9 O K 360 min Winter 257.684 0.684 3.3 48.8 O K 480 min Winter 257.667 0.667 3.2 47.4 O K 600 min Winter 257.644 0.644 3.2 45.5 O K 720 min Winter 257.619 0.619 3.1 43.5 O K 960 min Winter 257.569 0.569 3.0 39.4 O K 1440 min Winter 257.481 0.481 2.7 32.2 O K 2160 min Winter 257.379 0.379 2.4 23.8 O K 2880 min Winter 257.306 0.306 2.2 17.8 O K 4320 min Winter 257.215 0.215 1.8 10.4 O K 5760 min Winter 257.163 0.163 1.5 6.3 O K 7200 min Winter 257.131 0.131 1.3 4.0 O K 8640 min Winter 257.109 0.109 1.2 2.8 O K 10080 min Winter 257.093 0.093 1.1 2.0 O K

Storm Rain Time-Peak Event (mm/hr) (mins)

15 min Winter 79.865 18 30 min Winter 56.172 32 60 min Winter 38.009 60 120 min Winter 24.918 114 180 min Winter 19.161 144 240 min Winter 15.849 184 360 min Winter 12.112 260 480 min Winter 9.991 336 600 min Winter 8.597 410 720 min Winter 7.599 482 960 min Winter 6.248 618 1440 min Winter 4.731 882 2160 min Winter 3.574 1272 2880 min Winter 2.930 1640 4320 min Winter 2.216 2336 5760 min Winter 1.819 3056 7200 min Winter 1.562 3744 8640 min Winter 1.381 4408 10080 min Winter 1.245 5144

©1982-2010 Micro Drainage Ltd Paul Waite Associates Page 1 Summit House Burnley Road, Bacup Riparian Way Outfall 2 Keighley BD20 7BW 1 in 100yr + 30%CC Date 25/03/13 Designed By Donna Metcalf File Checked By Infrasoft Source Control W.12.4

Summary of Results for 100 year Return Period (+30%)

Storm Max Max Max Max Status Event Level Depth Control Volume (m) (m) (l/s) (m³)

15 min Summer 257.412 0.412 2.5 26.5 O K 30 min Summer 257.534 0.534 2.9 36.5 O K 60 min Summer 257.660 0.660 3.2 46.9 O K 120 min Summer 257.758 0.758 3.5 54.8 O K 180 min Summer 257.791 0.791 3.5 57.4 O K 240 min Summer 257.806 0.806 3.6 58.5 O K 360 min Summer 257.813 0.813 3.6 59.1 O K 480 min Summer 257.804 0.804 3.6 58.4 O K 600 min Summer 257.787 0.787 3.5 57.1 O K 720 min Summer 257.767 0.767 3.5 55.5 O K 960 min Summer 257.727 0.727 3.4 52.3 O K 1440 min Summer 257.649 0.649 3.2 45.9 O K 2160 min Summer 257.550 0.550 2.9 37.8 O K 2880 min Summer 257.473 0.473 2.7 31.5 O K 4320 min Summer 257.364 0.364 2.4 22.6 O K 5760 min Summer 257.292 0.292 2.1 16.7 O K 7200 min Summer 257.243 0.243 1.9 12.7 O K 8640 min Summer 257.207 0.207 1.7 9.8 O K 10080 min Summer 257.180 0.180 1.6 7.6 O K

Storm Rain Time-Peak Event (mm/hr) (mins)

15 min Summer 102.866 18 30 min Summer 73.221 32 60 min Summer 49.937 62 120 min Summer 32.721 116 180 min Summer 24.983 146 240 min Summer 20.537 178 360 min Summer 15.556 246 480 min Summer 12.742 316 600 min Summer 10.901 386 720 min Summer 9.587 454 960 min Summer 7.817 588 1440 min Summer 5.843 852 2160 min Summer 4.351 1232 2880 min Summer 3.532 1588 4320 min Summer 2.636 2332 5760 min Summer 2.144 3056 7200 min Summer 1.829 3752 8640 min Summer 1.609 4488 10080 min Summer 1.446 5152

©1982-2010 Micro Drainage Ltd Paul Waite Associates Page 2 Summit House Burnley Road, Bacup Riparian Way Outfall 2 Keighley BD20 7BW 1 in 100yr + 30%CC Date 25/03/13 Designed By Donna Metcalf File Checked By Infrasoft Source Control W.12.4

Summary of Results for 100 year Return Period (+30%)

Storm Max Max Max Max Status Event Level Depth Control Volume (m) (m) (l/s) (m³)

15 min Winter 257.453 0.453 2.7 29.8 O K 30 min Winter 257.592 0.592 3.1 41.3 O K 60 min Winter 257.739 0.739 3.4 53.2 O K 120 min Winter 257.889 0.889 3.8 63.0 O K 180 min Winter 258.525 1.525 5.0 64.8 O K 240 min Winter 258.988 1.988 5.7 65.2 Flood Risk 360 min Winter 258.882 1.882 5.5 65.1 Flood Risk 480 min Winter 258.325 1.325 4.6 64.6 O K 600 min Winter 257.888 0.888 3.8 63.0 O K 720 min Winter 257.834 0.834 3.6 60.4 O K 960 min Winter 257.762 0.762 3.5 55.1 O K 1440 min Winter 257.644 0.644 3.2 45.5 O K 2160 min Winter 257.506 0.506 2.8 34.2 O K 2880 min Winter 257.408 0.408 2.5 26.2 O K 4320 min Winter 257.283 0.283 2.1 16.0 O K 5760 min Winter 257.211 0.211 1.8 10.1 O K 7200 min Winter 257.167 0.167 1.5 6.6 O K 8640 min Winter 257.138 0.138 1.4 4.5 O K 10080 min Winter 257.117 0.117 1.2 3.2 O K

Storm Rain Time-Peak Event (mm/hr) (mins)

15 min Winter 102.866 18 30 min Winter 73.221 32 60 min Winter 49.937 60 120 min Winter 32.721 116 180 min Winter 24.983 140 240 min Winter 20.537 174 360 min Winter 15.556 248 480 min Winter 12.742 330 600 min Winter 10.901 416 720 min Winter 9.587 490 960 min Winter 7.817 628 1440 min Winter 5.843 898 2160 min Winter 4.351 1280 2880 min Winter 3.532 1648 4320 min Winter 2.636 2376 5760 min Winter 2.144 3064 7200 min Winter 1.829 3752 8640 min Winter 1.609 4488 10080 min Winter 1.446 5144

APPENDIX K Attenuation Calculations Outfall 3

Paul Waite Associates Page 1 Summit House Burnley Road, Bacup Riparian Way Outfall 3 Keighley BD20 7BW 1 in 1 year + 30%CC Date 25/3/13 Designed By Donna Metcalf File Checked By Infrasoft Source Control W.12.4

Summary of Results for 1 year Return Period (+30%)

Storm Max Max Max Max Status Event Level Depth Control Volume (m) (m) (l/s) (m³)

15 min Summer 255.851 0.151 1.3 4.0 O K 30 min Summer 255.873 0.173 1.4 5.1 O K 60 min Summer 255.893 0.193 1.5 6.0 O K 120 min Summer 255.907 0.207 1.6 6.7 O K 180 min Summer 255.911 0.211 1.6 6.8 O K 240 min Summer 255.910 0.210 1.6 6.8 O K 360 min Summer 255.903 0.203 1.6 6.4 O K 480 min Summer 255.894 0.194 1.5 6.0 O K 600 min Summer 255.885 0.185 1.5 5.6 O K 720 min Summer 255.877 0.177 1.5 5.2 O K 960 min Summer 255.862 0.162 1.4 4.5 O K 1440 min Summer 255.837 0.137 1.3 3.4 O K 2160 min Summer 255.813 0.113 1.1 2.3 O K 2880 min Summer 255.795 0.095 1.0 1.6 O K 4320 min Summer 255.772 0.072 0.8 1.0 O K 5760 min Summer 255.759 0.059 0.7 0.6 O K 7200 min Summer 255.754 0.054 0.6 0.5 O K 8640 min Summer 255.750 0.050 0.6 0.5 O K 10080 min Summer 255.747 0.047 0.5 0.4 O K

Storm Rain Time-Peak Event (mm/hr) (mins)

15 min Summer 32.700 16 30 min Summer 22.858 29 60 min Summer 15.709 46 120 min Summer 10.691 82 180 min Summer 8.523 116 240 min Summer 7.209 150 360 min Summer 5.673 218 480 min Summer 4.788 282 600 min Summer 4.200 344 720 min Summer 3.775 408 960 min Summer 3.186 530 1440 min Summer 2.509 768 2160 min Summer 1.981 1128 2880 min Summer 1.668 1476 4320 min Summer 1.306 2204 5760 min Summer 1.095 2936 7200 min Summer 0.950 3664 8640 min Summer 0.846 4328 10080 min Summer 0.766 5064

©1982-2010 Micro Drainage Ltd Paul Waite Associates Page 2 Summit House Burnley Road, Bacup Riparian Way Outfall 3 Keighley BD20 7BW 1 in 1 year + 30%CC Date 25/3/13 Designed By Donna Metcalf File Checked By Infrasoft Source Control W.12.4

Summary of Results for 1 year Return Period (+30%)

Storm Max Max Max Max Status Event Level Depth Control Volume (m) (m) (l/s) (m³)

15 min Winter 255.863 0.163 1.4 4.6 O K 30 min Winter 255.889 0.189 1.5 5.8 O K 60 min Winter 255.911 0.211 1.6 6.8 O K 120 min Winter 255.924 0.224 1.7 7.5 O K 180 min Winter 255.924 0.224 1.7 7.5 O K 240 min Winter 255.919 0.219 1.6 7.2 O K 360 min Winter 255.903 0.203 1.6 6.5 O K 480 min Winter 255.888 0.188 1.5 5.7 O K 600 min Winter 255.874 0.174 1.4 5.1 O K 720 min Winter 255.861 0.161 1.4 4.5 O K 960 min Winter 255.839 0.139 1.3 3.5 O K 1440 min Winter 255.809 0.109 1.1 2.2 O K 2160 min Winter 255.782 0.082 0.9 1.2 O K 2880 min Winter 255.766 0.066 0.8 0.8 O K 4320 min Winter 255.753 0.053 0.6 0.5 O K 5760 min Winter 255.748 0.048 0.5 0.4 O K 7200 min Winter 255.743 0.043 0.4 0.4 O K 8640 min Winter 255.740 0.040 0.4 0.3 O K 10080 min Winter 255.738 0.038 0.4 0.3 O K

Storm Rain Time-Peak Event (mm/hr) (mins)

15 min Winter 32.700 16 30 min Winter 22.858 30 60 min Winter 15.709 48 120 min Winter 10.691 88 180 min Winter 8.523 126 240 min Winter 7.209 162 360 min Winter 5.673 230 480 min Winter 4.788 298 600 min Winter 4.200 362 720 min Winter 3.775 426 960 min Winter 3.186 548 1440 min Winter 2.509 780 2160 min Winter 1.981 1128 2880 min Winter 1.668 1472 4320 min Winter 1.306 2204 5760 min Winter 1.095 2912 7200 min Winter 0.950 3664 8640 min Winter 0.846 4352 10080 min Winter 0.766 5088

©1982-2010 Micro Drainage Ltd Paul Waite Associates Page 1 Summit House Burnley Road, Bacup Riparian Way Outfall 3 Keighley BD20 7BW 1 in 30 year + 30%CC Date 25/3/13 Designed By Donna Metcalf File Checked By Infrasoft Source Control W.12.4

Summary of Results for 30 year Return Period (+30%)

Storm Max Max Max Max Status Event Level Depth Control Volume (m) (m) (l/s) (m³)

15 min Summer 255.990 0.290 1.9 10.6 O K 30 min Summer 256.060 0.360 2.1 14.1 O K 60 min Summer 256.120 0.420 2.3 17.0 O K 120 min Summer 256.162 0.462 2.4 19.0 O K 180 min Summer 256.172 0.472 2.5 19.5 O K 240 min Summer 256.171 0.471 2.5 19.4 O K 360 min Summer 256.158 0.458 2.4 18.8 O K 480 min Summer 256.140 0.440 2.4 17.9 O K 600 min Summer 256.121 0.421 2.3 17.0 O K 720 min Summer 256.102 0.402 2.3 16.1 O K 960 min Summer 256.067 0.367 2.2 14.4 O K 1440 min Summer 256.008 0.308 2.0 11.5 O K 2160 min Summer 255.944 0.244 1.7 8.4 O K 2880 min Summer 255.900 0.200 1.6 6.3 O K 4320 min Summer 255.846 0.146 1.3 3.8 O K 5760 min Summer 255.815 0.115 1.1 2.4 O K 7200 min Summer 255.795 0.095 1.0 1.6 O K 8640 min Summer 255.780 0.080 0.9 1.2 O K 10080 min Summer 255.770 0.070 0.8 0.9 O K

Storm Rain Time-Peak Event (mm/hr) (mins)

15 min Summer 79.865 17 30 min Summer 56.172 31 60 min Summer 38.009 56 120 min Summer 24.918 88 180 min Summer 19.161 124 240 min Summer 15.849 158 360 min Summer 12.112 228 480 min Summer 9.991 296 600 min Summer 8.597 362 720 min Summer 7.599 426 960 min Summer 6.248 556 1440 min Summer 4.731 796 2160 min Summer 3.574 1168 2880 min Summer 2.930 1528 4320 min Summer 2.216 2244 5760 min Summer 1.819 2944 7200 min Summer 1.562 3672 8640 min Summer 1.381 4400 10080 min Summer 1.245 5136

©1982-2010 Micro Drainage Ltd Paul Waite Associates Page 2 Summit House Burnley Road, Bacup Riparian Way Outfall 3 Keighley BD20 7BW 1 in 30 year + 30%CC Date 25/3/13 Designed By Donna Metcalf File Checked By Infrasoft Source Control W.12.4

Summary of Results for 30 year Return Period (+30%)

Storm Max Max Max Max Status Event Level Depth Control Volume (m) (m) (l/s) (m³)

15 min Winter 256.018 0.318 2.0 12.0 O K 30 min Winter 256.100 0.400 2.3 16.0 O K 60 min Winter 256.173 0.473 2.5 19.5 O K 120 min Winter 256.218 0.518 2.6 21.7 O K 180 min Winter 256.226 0.526 2.6 22.1 O K 240 min Winter 256.219 0.519 2.6 21.7 O K 360 min Winter 256.191 0.491 2.5 20.4 O K 480 min Winter 256.159 0.459 2.4 18.9 O K 600 min Winter 256.127 0.427 2.3 17.3 O K 720 min Winter 256.098 0.398 2.3 15.9 O K 960 min Winter 256.046 0.346 2.1 13.4 O K 1440 min Winter 255.967 0.267 1.8 9.5 O K 2160 min Winter 255.892 0.192 1.5 5.9 O K 2880 min Winter 255.847 0.147 1.3 3.8 O K 4320 min Winter 255.799 0.099 1.0 1.8 O K 5760 min Winter 255.775 0.075 0.9 1.0 O K 7200 min Winter 255.761 0.061 0.7 0.7 O K 8640 min Winter 255.756 0.056 0.7 0.6 O K 10080 min Winter 255.752 0.052 0.6 0.5 O K

Storm Rain Time-Peak Event (mm/hr) (mins)

15 min Winter 79.865 17 30 min Winter 56.172 31 60 min Winter 38.009 58 120 min Winter 24.918 94 180 min Winter 19.161 134 240 min Winter 15.849 172 360 min Winter 12.112 244 480 min Winter 9.991 316 600 min Winter 8.597 384 720 min Winter 7.599 450 960 min Winter 6.248 580 1440 min Winter 4.731 826 2160 min Winter 3.574 1188 2880 min Winter 2.930 1532 4320 min Winter 2.216 2244 5760 min Winter 1.819 2936 7200 min Winter 1.562 3632 8640 min Winter 1.381 4376 10080 min Winter 1.245 5136

©1982-2010 Micro Drainage Ltd Paul Waite Associates Page 1 Summit House Burnley Road, Bacup Riparian Way Outfall 3 Keighley BD20 7BW 1 in 100 year + 30%CC Date 25/3/13 Designed By Donna Metcalf File Checked By Infrasoft Source Control W.12.4

Summary of Results for 100 year Return Period (+30%)

Storm Max Max Max Max Status Event Level Depth Control Volume (m) (m) (l/s) (m³)

15 min Summer 256.057 0.357 2.1 13.9 O K 30 min Summer 256.158 0.458 2.4 18.8 O K 60 min Summer 256.251 0.551 2.7 23.3 O K 120 min Summer 256.319 0.619 2.8 26.3 O K 180 min Summer 256.340 0.640 2.9 27.0 O K 240 min Summer 256.339 0.639 2.9 26.9 O K 360 min Summer 256.316 0.616 2.8 26.2 O K 480 min Summer 256.289 0.589 2.8 25.0 O K 600 min Summer 256.263 0.563 2.7 23.8 O K 720 min Summer 256.237 0.537 2.6 22.6 O K 960 min Summer 256.189 0.489 2.5 20.3 O K 1440 min Summer 256.109 0.409 2.3 16.4 O K 2160 min Summer 256.022 0.322 2.0 12.2 O K 2880 min Summer 255.962 0.262 1.8 9.3 O K 4320 min Summer 255.888 0.188 1.5 5.8 O K 5760 min Summer 255.845 0.145 1.3 3.7 O K 7200 min Summer 255.819 0.119 1.2 2.6 O K 8640 min Summer 255.800 0.100 1.0 1.8 O K 10080 min Summer 255.786 0.086 0.9 1.4 O K

Storm Rain Time-Peak Event (mm/hr) (mins)

15 min Summer 102.866 18 30 min Summer 73.221 32 60 min Summer 49.937 60 120 min Summer 32.721 92 180 min Summer 24.983 126 240 min Summer 20.537 162 360 min Summer 15.556 230 480 min Summer 12.742 300 600 min Summer 10.901 366 720 min Summer 9.587 434 960 min Summer 7.817 560 1440 min Summer 5.843 810 2160 min Summer 4.351 1172 2880 min Summer 3.532 1532 4320 min Summer 2.636 2248 5760 min Summer 2.144 2944 7200 min Summer 1.829 3672 8640 min Summer 1.609 4408 10080 min Summer 1.446 5136

©1982-2010 Micro Drainage Ltd Paul Waite Associates Page 2 Summit House Burnley Road, Bacup Riparian Way Outfall 3 Keighley BD20 7BW 1 in 100 year + 30%CC Date 25/3/13 Designed By Donna Metcalf File Checked By Infrasoft Source Control W.12.4

Summary of Results for 100 year Return Period (+30%)

Storm Max Max Max Max Status Event Level Depth Control Volume (m) (m) (l/s) (m³)

15 min Winter 256.094 0.394 2.2 15.7 O K 30 min Winter 256.211 0.511 2.6 21.4 O K 60 min Winter 256.330 0.630 2.9 26.6 O K 120 min Winter 257.321 1.621 4.7 29.0 Flood Risk 180 min Winter 257.480 1.780 4.9 29.2 Flood Risk 240 min Winter 257.260 1.560 4.6 29.0 Flood Risk 360 min Winter 256.649 0.949 3.5 28.4 O K 480 min Winter 256.334 0.634 2.9 26.8 O K 600 min Winter 256.285 0.585 2.8 24.8 O K 720 min Winter 256.244 0.544 2.7 22.9 O K 960 min Winter 256.173 0.473 2.5 19.6 O K 1440 min Winter 256.065 0.365 2.2 14.3 O K 2160 min Winter 255.961 0.261 1.8 9.2 O K 2880 min Winter 255.897 0.197 1.5 6.2 O K 4320 min Winter 255.829 0.129 1.2 3.0 O K 5760 min Winter 255.795 0.095 1.0 1.7 O K 7200 min Winter 255.776 0.076 0.9 1.0 O K 8640 min Winter 255.764 0.064 0.8 0.7 O K 10080 min Winter 255.757 0.057 0.7 0.6 O K

Storm Rain Time-Peak Event (mm/hr) (mins)

15 min Winter 102.866 17 30 min Winter 73.221 31 60 min Winter 49.937 60 120 min Winter 32.721 88 180 min Winter 24.983 126 240 min Winter 20.537 162 360 min Winter 15.556 240 480 min Winter 12.742 320 600 min Winter 10.901 392 720 min Winter 9.587 458 960 min Winter 7.817 590 1440 min Winter 5.843 840 2160 min Winter 4.351 1208 2880 min Winter 3.532 1560 4320 min Winter 2.636 2252 5760 min Winter 2.144 2944 7200 min Winter 1.829 3672 8640 min Winter 1.609 4344 10080 min Winter 1.446 5136

APPENDIX L Preliminary Drainage Layout