FLOOD RISK ASSESSMENT Proposed Development at Foster Street, Harlow, Essex, CM17 9HS C J Pryor Ltd & Anderson Design An

FLOOD RISK ASSESSMENT

for

Proposed Development at Foster Street, Harlow, Essex, CM17 9HS Grid Reference: 548850E,209000N

Prepared on behalf of C J Pryor Ltd & Anderson Design and Build

August 2014 Reference: ST2331/FRA-1408-Foster Street Revision 0

Flood Risk Assessment Foster Street, Harlow

This report has been prepared by Stomor Ltd. based upon information obtained from others. Stomor Ltd cannot be held responsible for inaccuracies in this information.

This report has been prepared for the Client for their sole and specific use. No professional liability or warranty shall be extended to other parties in connection with this report without the explicit written agreement of Stomor Ltd and payment of the appropriate fee.

Should the Client wish to pass copies of this report to others for information, the entire report should be copied.

Revision Author Checked by Issue Date 0 SJB NJM 11.08.14

Ref: ST2331/FRA-1408-Foster Street i

Flood Risk Assessment Foster Street, Harlow

CONTENTS

1. Introduction Page 1

2. Site Location Page 4

3. Site Background Page 6

4. Existing Drainage Page 8

5. Proposed Development Page 11

6. Proposed Site Drainage Page 12

7. Potential Sources of Flooding Page 19

8. Summary and Recommendations Page 22

APPENDICES

A Site Location Plan, ST-2331-20

B Thames Water Utilities Sewer Records

C Greenfield Runoff Calculations

D Indicative Drainage Strategies, ST-2331-18-A & ST-2331-19-A

E Pre-Development Enquiry & TWU Correspondence

Ref: ST2331/FRA-1408-Foster Street ii

Flood Risk Assessment Foster Street, Harlow

1.0 Introduction

1.1 Stomor Ltd. has been commissioned by C J Pryor Ltd and Anderson Design and Build to prepare a Flood Risk Assessment (FRA) associated with proposed development on Foster Street, Harlow. A Site Location Plan, Drawing ST-2331-20, is provided in Appendix A.

1.2 The proposed development is to be split across two sites located on the north and south sides of Foster Street. The southern site covers a total area of approximately 2.7ha which is under the ownership of C J Pryor Ltd and comprises two parcels of land; the operational brownfield western part, and the greenfield eastern part. The northern site covers an area of approximately 0.57ha and is currently under the ownership of C J Pryor Ltd.

1.3 For the purposes of this assessment, the northern site will be referred to as the Foster Street North and the southern site will be referred to as the Foster Street South.

1.4 The proposed development of the two sites will be assessed for up to 16 residential units on the Foster Street North site and up to 69 residential units on the Foster Street South site. Current proposals for the sites comprise a lower number of 9 and 65 units on the north and south sites respectively, but to provide a more robust assessment the higher figures will be used in the Flood Risk Assessment.

1.5 Policy Context

1.5.1 This FRA has been prepared in accordance with the relevant national, regional and local planning policy and statutory authority guidance as follows:

 National policy regarding flood risk as contained within the National Planning Policy Framework (NPPF) dated March 2012, issued by Communities and Local Government and the accompanying Planning Practice Guidance.

 The Environment Agency (EA) Flood Risk Standing Advice (FRSA) version 3.1 issued April 2012.

 Epping Forest District Council (EFDC) Combine Policies Local Plan (1998) & Alterations (2006), published in 2008; Policies U2A – Development in Flood Risk Areas, U2B – Flood Risk Assessment Zones, U3A - Catchment Areas and U3B - Sustainable Drainage Systems.

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 EFDC & Harlow Council (HC) Strategic Flood Risk Assessment (SFRA) issued April 2011.

1.5.2 Furthermore, the FRA follows the methodology prescribed in CIRIA document C624: Development and Flood Risk, Guidance for the Construction Industry.

1.6 Vulnerability and the NPPF Sequential Test

1.6.1 The NPPF follows a sequential risk based approach in determining the suitability of land for development in flood risk areas, with the intention of steering all new development to the lowest flood risk areas.

1.6.2 The Indicative Floodplain Map obtained from the EA website is provided in Figure 1.1, which shows that the site lies within Flood Zone 1 – Low Probability of Flooding.

Figure 1.1 - Environment Agency Indicative Floodplain Map (http://maps.environment-agency.gov.uk)

1.6.3 Flood Zones 1, 2 and 3 are described in the table below: Zone 1 Land assessed as having a less than 1 in 1000 annual probability of river or Low Probability sea flooding in any year (<0.1%) Zone 2 Land assessed as having between a 1 in 100 and 1 in 1000 annual Medium probability of river flooding (1% - 0.1%) or between a 1 in 200 and 1 in 1000 Probability annual probability of sea flooding (0.55% – 0.1%) in any year. Land assessed as having a 1 in 100 or greater annual probability of river Zone 3a flooding (>1%) or a 1 in 200 or greater annual probability of flooding from the High Probability sea (>0.5%) in any year.

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Land where water has to flow or be stored in times of flood. (Land which Zone 3b would flood with an annual probability of 1 in 20 (5%) or greater in any year The Functional or is designed to flood in an extreme (0.1%) flood, or at another probability to Floodplain be agreed between the LPA and the Environment Agency, including water conveyance routes).

1.6.4 The Flood Risk and Costal Change Category (ID 7) of the PPG and associated documents set out that for sites in Flood Zone 1, development proposals on sites comprising one hectare or above the vulnerability to flooding from other sources as well as from river and sea flooding, and the potential to increase flood risk elsewhere through the addition of hard surfaces and the effect of the new development on surface water run-off, should be incorporated in a flood risk assessment. This need only be brief unless the factors above or other local considerations require particular attention.

1.6.5 The Flood Risk and Costal Change Category of the PPG and associated documents identifies that site-specific flood risk assessments should identify and assess the risks of all forms of flooding to and from the development and demonstrate how these flood risks will be managed so that the development remains safe throughout its lifetime, taking climate change into account.

1.6.6 The proposed development will be situated within Flood Zone 1, as identified by Figure 1.1 above. PPG identifies that all uses of land are appropriate within this Flood Zone.

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2.0 Site Location

2.1 The sites are located in the hamlet of Foster Street, to the east of Harlow and the M11. As previously stated the proposed development is to be split across two sites; Foster Street North, on the north side of Foster Street, and Foster Street South, on the south side.

2.2 The nearest watercourse to the sites is Shonks Brook which is located approximately 860m to the south. However, the EA Indicative Flood Maps indicate that a tributary for Shonks Brook runs along the southern side of the Foster Street South site to connect to Shonks Brook near to the junction between Mill Street and Hastingwood Road. Shonks Brook runs from the M11 towards the south east to connect to Crispey Brook which in turn connects to the River Roding in Chipping Ongar.

2.3 Foster Street North Site

2.3.1 The Foster Street North site is brownfield and currently comprises several agricultural buildings which are generally surrounded by gravelled areas. The main access to the site is a gated access taken from Foster Street to the south east, although there also appears to be an additional access from the west of the site via a gravel track from Foster Street.

2.3.2 There are several drainage ditches in the vicinity of the site, with ditches in place along the north and north east boundaries. In addition, a drainage ditch runs through part of the south west side of the site.

2.3.3 An Affinity Water pumping station and electricity sub-station are currently located in the south west of the site, with associated overhead power lines running towards the north before heading east and west from the north west corner of the site.

2.3.4 Agricultural land surrounds the site to the north, east and west. Foster Street abuts the south of the site, while two residential properties known as ‘Old Farm Cottages’ abut the site to the south east. There is a parcel of land to the west of the site between the western boundary and properties No. 1 & 2 Shoe Lane.

2.3.5 The highest recorded level on the site is 97.26m Above Ordinance Datum (AOD) recorded on the north east side of the electricity sub-station. Excluding the drainage ditches, the lowest site level is 95.86m AOD located in the north eastern corner.

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2.4 Foster Street South Site

2.4.1 The southern site is formed of two parcels of land; the existing operational brownfield part on the western part of the site covering an area of approximately 1.3ha, and an area of greenfield land to the east which covers the remainder of the site which is sometimes used for the storage of vehicles and earth moving equipment.

2.4.2 The operational western part currently comprises a 2 storey office, associated car park and a large metal barn. To south of the offices is a large area of concrete where plant is currently stored and maintained.

2.4.3 Access to operational part of the site is currently taken from Foster Street to the north. Access to the greenfield part of the site appears to be taken from Foster Street via land to the east of the site, although a gated access is available from the western site.

2.4.4 A 35m high telephone mast is currently situated in the centre of the site, between the areas of brownfield and greenfield, access to this mast is taken through the western site.

2.4.5 Trees and hedges are present along the majority of the southern, eastern and western boundaries of the site. Raised bunds run along the western, southern and eastern boundaries of the southern part of the operational site. There are no raised bunds along the eastern or southern boundaries of the greenfield part of the site.

2.4.6 Drainage ditches run adjacent to the northern, eastern and southern boundaries of the site.

2.4.7 North Weald Bassett Public Footpath 201_61 runs from north east to south east through the south east corner of the site. This footpath originates from Foster Street and runs in a south westerly direction towards Mill Street. In addition, North Weald Bassett Public Byway 201_21 runs adjacent to the southern boundary of the site. The Byway runs from Green Lane to the east to Foster Street to the north west.

2.4.8 Foster Street runs along the northern boundary of the site, while the property known as Searles Farm abuts the site to the west. There are several residential properties which separate the site from Foster Street in the north eastern corner and a property with stables at the rear which abut the site to the east. Agricultural land neighbours the site to the south and south east, beyond the public highway.

2.4.9 Excluding the levels associated with raised bunds and drainage ditches, the highest recorded level is 99.02m AOD in the west of the site and the lowest recorded level is 96.80m AOD in the south east corner.

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3.0 Site Background

3.1 Foster Street North Site

3.1.1 Historical maps identify that from 1874 the majority of the site was greenfield apart from a single building in the south eastern corner. The site primarily appears to remain unchanged up until 1974 where several additional farm buildings are apparent across the site as well as the electricity sub-station and Affinity Water pumping station.

3.2 Foster Street South Site

3.2.1 Interrogation of historical maps identify that from 1874 the site was part of Seale’s Farm, which primarily comprised greenfield land apart from some farm buildings in the north west corner of the site. Additional buildings associated with the farm appear on historic maps from 1920 and 1940 as well as several buildings to the north east and east in 1974. At some point between 1960 and 1974, the name of Seale’s Farm has been changed to Searles Farm. In 1984 the historic maps show that several bunds were installed along some of the boundaries in the south west part of the site.

3.3 General

3.3.1 In addition to the above, the historic maps identified that from 1896 there were several large drains/ponds on both sides of Foster Street. By 1974 the large drains/ponds had become elongated to form the channels which are present today.

3.3.2 The Indicative Flood Plain Map from the EA identifies that the site lies within Flood Zone 1, within land assessed to have less than a 1 in 1000 annual probability of flooding from a fluvial source, and well outside of any flood plain associated with a main river.

3.3.3 The sites are not situated within, or near, an EA designated Groundwater Source Protection Zone.

3.3.4 A Level 1 SFRA for the area was prepared by EFDC and HC, in April 2011. The SFRA is used as a desk based study to map all forms of flood risk to provide an evidence basis to locate new development primarily within low risk areas. The information allows the planning authority to identify the level of detail required for site-specific Flood Risk Assessments.

3.3.5 The SFRA identified that the district has a history of flooding although the majority of incidents have either occurred within the vicinity of watercourses or in dense urban areas. Several major flooding events have been recorded in Harlow, although the SFRA

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identifies that these events were mostly confined to the functional flood plain and that the town’s development has ameliorated the potential flooding within urban areas.

3.3.6 The SFRA also identified that the majority of Epping Forest, including the site, is underlain by London Clay and would therefore preclude the use of infiltration as a sole method for discharging surface water. This is supported by interrogation of the British Geological Survey (BGS) website and borehole log data in the vicinity of the site which identifies that the ground conditions are generally London Clay overlain by silty clay with chalk fragments.

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4.0 Existing Drainage

4.1 Investigations into the existing drainage of the site have been carried out using the above information in conjunction with the topographical survey and site inspection. TWU public sewer records have also been obtained in order to identify the available public sewer networks in the vicinity of the site. A copy of the TWU sewer records is provided in Appendix B.

4.2 TWU sewer records show that there are no public surface water sewers in the vicinity of the site. A 150mm diameter public foul water sewer runs towards the east along Foster Street to a foul pumping station located at the junction between Foster Street and Green Lane. From here, an 80mm diameter rising main runs westbound along Foster Street to connect into a 100mm diameter rising main where Foster Street turns into Harlow Common, which in turn discharges into a 225mm diameter public foul water sewer on the west side of the M11.

4.3 Foster Street North Site

4.3.1 Inspection of the topographical survey indicates that surface water runoff associated with the northern part of the site generally falls towards one of the adjacent drainage ditches. Levels within the southern part of the site generally fall towards the east towards a drainage channel, although runoff in the south west corner of the site drains to the drainage ditch located within this area.

4.3.2 As previously mentioned, a drainage ditch has been identified in the south west of the site. The topographical survey identifies that the ditch originates from the west and runs adjacent to the north side of Foster Street before being culverted via a 300mm diameter pipe under the western site access, which also serves the electricity sub-station and clean water pump station. The ditch is re-established as it enters the site and runs towards the north, to a point just north of the clean water pump station. From here it is assumed that the ditch becomes culverted and discharges into the drainage ditch along the northern side of the site. The survey identifies that a 225mm diameter pipe and a 450mm diameter pipe currently discharge into the ditch within the site.

4.3.3 The drainage ditch to the north east of the site runs north then west, adjacent to the site boundary, to the north west corner of the site where flows continue along a 225mm diameter pipe towards the north west. On-site investigations have identified that a 225mm diameter outfall discharges into the drainage ditch at the north west corner, which may take flows from the ditch in the south west corner.

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4.3.4 Geological information and borehole log data for the area in the vicinity of the site has been obtained from the BGS website. This information identifies that the ground conditions in the vicinity of the site generally comprise silty clay with chalk fragments underlain by London Clay, which indicates that infiltration methods would not be suitable for the disposal of surface water from the site.

4.3.5 A calculation of greenfield runoff from the existing site has been undertaken based on The SuDS Manual C697 and EA/Defra Technical Report W5-074/A to assess flows up to 100 year + 30% Climate Change return periods, where:

Qbar = typical greenfield runoff generated from a 1 in 2 year event, AREA = area of whole site, SAAR = Standard Average Annual Rainfall, SPR = Soil Percentage Runoff.

4.3.6 Based upon the overall area of the development site of 0.57ha, this greenfield runoff calculation gives the following flow rates:

Storm Event Greenfield Runoff Rate 1 in 1 year 1.16l/s 1 in 30 year 3.01l/s 1 in 100 year 4.31l/s

4.3.7 A copy of the greenfield runoff calculation sheet is provided in Appendix C.

4.3.8 Foul flows from the site currently discharge to an on-site cesspit located on the eastern side of the site. No foul flows from the site appear to currently discharge into the public foul water sewer.

4.4 Foster Street South Site

4.4.1 Inspection of the topographical survey has identified drainage ditches run along the northern, eastern and southern boundaries of the site. Levels within the greenfield part of the site, and in the southern part of the brownfield area, generally fall towards the south east towards the drainage ditches. The survey has identified 3No. petrol interceptors in the centre of the southern boundary. In addition, a 450mm diameter outfall to the southern drainage ditch has also been identified in this location.

4.4.2 The topographical survey has identified that there is existing drainage infrastructure associated with the brownfield area of the site. Surface water within the developed area drains to a 150mm diameter drain, either via gullies or petrol interceptor, before discharging into the drainage ditch which runs along the northern boundary.

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4.4.3 As previously stated, BGS information has identified that the ground conditions in the vicinity of the site generally comprises silty clay with chalk fragments underlain by London Clay, which indicates that infiltration methods would not be suitable for the disposal of surface water from the site.

4.4.4 A calculation of greenfield runoff from the existing site has been undertaken based on The SuDS Manual C697 and EA/Defra Technical Report W5-074/A to assess flows up to 100 year + 30% Climate Change return periods, where:

Qbar = typical greenfield runoff generated from a 1 in 2 year event, AREA = area of whole site, SAAR = Standard Average Annual Rainfall, SPR = Soil Percentage Runoff.

4.4.5 Based upon the overall area of the site of 2.7ha, this greenfield runoff calculation gives the following flow rates:

Storm Event Greenfield Runoff Rate 1 in 1 year 5.53l/s 1 in 30 year 14.30l/s 1 in 100 year 20.48l/s

4.4.6 A copy of the greenfield runoff calculation sheet is provided in Appendix C.

4.4.7 With regard to foul flows, the topographical survey has identified that there is existing foul drainage infrastructure in the vicinity of the existing office building in the north east of the site. Foul flows drain via a 100mm diameter before discharging to the public foul water sewer in Foster Street. In addition, the topographical survey has identified 3No. 100mm diameter foul drains entering the site from the adjacent residential property to the west.

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5.0 Proposed Development

5.1 As previously stated, the proposed development is to be split across two sites. The Foster Street South site covers a total area of approximately 2.7ha and the Foster Street North site covers an area of approximately 0.57ha.

5.2 For the purposes of this assessment, the proposed development at the Foster Street South site will be assessed for up to 69 residential uses, while the Foster Street North site will be assessed for up to 16 residential units.

5.3 The new buildings, roads, hardstandings and other new impermeable areas on the site are assumed to cover 60% of the total site area which would equate to 1.63ha for the south site and 0.34ha for the north site.

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6.0 Proposed Site Drainage

6.1 Surface Water Drainage

6.1.1 As previously described, the developable site area of north and sites are 0.57ha and 2.7ha respectively. Assuming that 60% of the site is to be impermeable, development proposals could generate an impermeable area of up to 0.34ha on the Foster Street North site and 1.63ha on the Foster Street South site.

6.1.2 In order to meet Code for Sustainable Homes SUR1 requirements, the proposed development runoff should be equal to or less than the existing greenfield runoff associated with the 1 in 1 year and 1 in 100 year storm events.

6.1.3 The majority of the Foster Street North site is currently brownfield and surface water runoff drains to one of the drainage ditches which run along the boundaries of the site.

6.1.4 The Foster Street South site is split into two parcels; the western parcel is primarily developed and the eastern parcel is greenfield. Surface water from the eastern parcel and the south of the western parcel currently discharge to one of the drainage ditches along the east or south boundary. Runoff associated with the impermeable area in the north of the western parcel currently discharges to the drainage ditch to the north, via either a 100mm or 150mm diameter outfalls.

6.1.5 An enquiry was sent to the EA requesting confirmation that surface water runoff from the Foster Street North site can discharge at a rate of 5l/s into the adjacent drainage ditches, and surface water runoff from the Foster Street South site can discharge at a rate equivalent to greenfield runoff into the drainage ditch along the southern boundary. In their response dated 18th July 2013, the EA confirmed that the proposed discharge rates and locations would be suitable.

6.1.6 As previously stated, the underlying ground conditions of the site indicate that infiltration methods would not be feasible. However, site specific soakage tests should be undertaken in order to determine the potential for infiltration.

6.1.7 Proposed drainage strategies for surface water have been prepared to identify potential SuDS measures which are considered feasible across the development sites. The strategy also demonstrates a proposed layout of flow control and attenuation features to enable maximum overall discharge rates of 5l/s and 10l/s during the 1 in 100 year storm event for the Foster Street North and Foster Street South sites respectively, with provision of sufficient storage to avoid flooding within the site during the 1 in 100 year +

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30% Climate Change event. Copies of the Indicative Drainage Strategy Parcel A, Drawing ST-2331-18-A, and Indicative Drainage Strategy Parcel B, Drawing ST-2331- 19-A, are provided in Appendix D.

6.1.8 The table below, shows the SuDS hierarchy and methods we would intend to promote

across the sites in accordance with the EA document “SuDS – A Practical Guide”:

SuDS Technique Remarks

Flood

Pollution

Reduction Reduction

Landscape andWildlife A living roof scheme is unlikely to Most be incorporated into the Living Roofs yes yes yes Sustainable masterplan due to cost and maintenance implications. Basins and Ponds Proposed on this scheme to cater -Constructed Wetlands for surface water storage. -Balancing Ponds yes yes yes Recommended in areas where -Detention Basins suitable in terms of health and -Retention Ponds safety and public amenity. Recommended in areas where Filter Strips and Swales yes yes yes suitable in terms of health and safety and public amenity. Infiltration Devices Underlying soil conditions suggest -Soakaways yes yes yes that infiltration devices would not -Infiltration Trenches and be feasible. Basins Permeable Surfaces and Filter Drains Proposed method of surface -Gravelled Areas yes yes - water source control from paved -Solid Paving Blocks areas. -Porous Paviors Cellular storage tanks or Tanked Systems oversized pipes have been Least -Oversized pipes/tanks yes - - proposed to cater for surface Sustainable -Storm Cells water storage during extreme storm events.

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6.1.9 Key features of the proposed SuDS scheme are as follows:

Foster Street North

i. Lined porous paving within private parking areas are to be considered, where appropriate, to control runoff at source and treat surface water runoff within the site. ii. Provision of a detention basin located in the south of the site to treat runoff from areas in the south of the site while also providing storage for all storm events up to and including the 1 in 100 year storm event + 30% allowance for Climate Change. iii. 450mm diameter pipework to transport water between the detention pond and the outfall, while also providing additional storage volume for attenuation.

Foster Street South

i. Lined porous paving within private parking areas and private roads where appropriate to control runoff at source and treat surface water runoff within the site. ii. Provision of swales/shallow depressions to provide storage for all storm events up to and including the 1 in 100 year storm event + 30% allowance for Climate Change. iii. Provision of 450mm diameter storage tanks and cellular crates under the internal road network, where appropriate, to provide storage for more frequent storm events.

6.1.10 The proposed SuDS solutions will need to have clear, enforceable maintenance regimes in place so that they provide effective flood protection and water treatment for the long term.

6.1.11 Sites within a Groundwater Protection Zones (GPZ) may require interceptors and/or other pollution control measures in order to discharge surface water from roads/car parks via soakaways. However, as this site is outside of any GPZ and the nature of the development is low risk, there should be no restrictions to the types of SuDS systems available for use.

6.1.12 In accordance with CIRIA and EA standards, certain levels of water quality treatment are required before surface water runoff from a proposed development can discharge into a receiving watercourse. The proposed use of the site would require a minimum of 1 level of treatment before discharging into the watercourse. The methods of treatment for the

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proposed development will be achieved by using SuDS techniques as detailed above and identified on the Indicative Drainage Strategies.

6.1.13 The CIRIA produced SuDS Manual (C697) identifies that porous paving and swales provide a high potential of water quality treatment associated with the removal of suspended solids, heavy metals and nutrients. In addition, porous paving also provides a high potential of treatment with regard to the removal of bacteria.

6.1.14 It is noted that the proposed site uses and SuDS systems will result in a significant improvement in the quality of surface water discharged from the two sites.

6.1.15 In accordance with EA policy, the drainage proposals should retain the 1 in 100 year storm within the site, without generating a flood risk to properties within or adjacent to the site. The EA Flood Risk Standing Advice requires the developer to also make provision for Climate Change, relating to a 30% increase in rainfall intensity.

6.1.16 Therefore, on-site attenuation will be required for additional flows generated by the development for all storms up to and including the 1 in 100 year plus 30% Climate Change critical storm, based upon an overall maximum discharge rate of 5l/s for the Foster Street North site and 10l/s for the Foster Street South site.

6.1.17 The storage volume required to accommodate the 1 in 100 year storm event plus a 30% allowance for Climate Change for the north and south sites would equate to the following:

 Foster Street North – 0.57ha total area of which 0.33ha assumed impermeable = 163m3.  Foster Street South – 2.7ha total area of which 1.7ha assumed impermeable = 1050m3.

6.1.18 The EA is a statutory consultee for Planning Applications in England. The above parameters for restricted runoff and storage volumes are actively encouraged by the EA at the planning stage of new developments. However, the adopting water authorities, i.e. TWU in this case, do not currently adopt piped systems which accommodate the 1 in 100 year storm event. Therefore, where surface water sewers are to be adopted, drainage systems need to be designed to accommodate the individual requirements of both the adopting authority (TWU) and the EA. Notwithstanding the above, SuDS schemes should be implemented as far as practicable.

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6.1.19 The above strategy must not be used for construction purposes and it is anticipated that the indicative proposals will be designed in detail to suit the proposed development layout. Storage volumes and drainage features must be confirmed by detailed design.

6.1.20 It is recommended that the developer considers the use of rainwater harvesting systems and water butts if practicable to intercept initial rainfall from roofs and reduce the overall volume of runoff.

6.1.21 Proposed buildings will need to be located away from any proposed public sewers; minimum distances will be in accordance with Sewers for Adoption 7th Edition. Man entry access points will be required at either end of a public sewer which passes through privately owned land. The access points should be sited within public areas with access availability at all times.

6.2 Foul Drainage

6.2.1 As previously stated, the nearest public foul water sewer is located within Foster Street, which runs between the two sections of the development site. This sewer runs eastbound to a pump station located adjacent to the junction between Foster Street and Green Lane which in turn pumps to the 225mm diameter public foul water sewer in Harlow Common.

6.2.2 Development of up to 16 residential units on the Foster Street North site would generate a peak foul flow of 0.74l/s, while a development of up to 69 residential units on the Foster Street South site would generate a peak foul flow of 3.19l/s, based upon 4000 litres/unit dwelling/day, in accordance with Sewers for Adoption 7th Edition.

6.2.3 A Pre-Development Enquiry was initially carried out with TWU based upon previous proposals for the Foster Street South site comprising a residential development of up to 86 units, which would generate a peak foul flow of 3.94l/s in accordance with Sewers for Adoption, and a development of 16 residential units on the Foster Street North site. The enquiry requested confirmation that foul water flows may be discharged to the public foul water sewer located in Foster Street, at a peak flow rate of 4l/s from the Foster Street South site and 0.75l/s from the Foster Street North site. In their response dated 5th August 2013, attached in Appendix E, TWU identified that the Foster Street foul water pump station is unlikely to be able to cope with the additional flows from the development and, therefore, an impact study would be necessary in order to determine if upgrades to the existing network would be required.

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6.2.4 The subsequent impact study was undertaken by TWU and concluded that the existing foul water sewer network does not have available capacity downstream of the proposed connection points to accept the proposed development flows and, therefore, improvements to the existing foul water system are required to enable the proposed connection to the sewer network.

6.2.5 Following TWU’s requirements for a proposed connection to the public network, a Section 98 application was submitted to determine the scope and cost of works associated with upgrading the public sewer infrastructure in order to agree to a connection from the development sites.

6.2.6 Strategies for the discharge of foul water from the Foster Street North and Foster Street South developments have been prepared and are shown in principle on Drawings ST- 2331-18-A and ST-2331-19-A, attached in Appendix D. These drawings show illustrative drainage layouts to demonstrate that the sites can be drained based upon the number of residential units to be developed. The drawings are strategies only and must not be used for construction purposes.

6.2.7 The Indicative Drainage Strategies identify the following:

Foster Street North

i. The strategy identifies a gravity connection to the 150mm diameter foul water sewer in Foster Street, with a proposed new manhole connection downstream of existing MH 8001.

Foster Street South

i. Foul flows from the development will drain to a pump station located in the north western corner of the site. From here, flows will be pumped to the public foul water sewer in Foster Street with a connection at MH 7901. It is noted that flows will be pumped to a new manhole on the site, with a gravity connection to the public sewer.

6.2.8 The topographical survey has identified that foul flows associated with Searles Farm, to the west of the site, currently drain through the site. Although not confirmed, it has been assumed that the flows discharge into the foul drainage system adjacent to the existing office building. Therefore, a connection from Searles Farm has been incorporated within the indicative drainage strategy which will need to be maintained through the on-site system as necessary.

Ref: ST2331/FRA-1408-Foster Street Page | 17 Flood Risk Assessment Foster Street, Harlow

6.2.9 Proposed buildings will need to be located away from any proposed public sewers; minimum distances will be in accordance with Sewers for Adoption 7th Edition. Man entry access points will be required at either end of a public sewer which passes through privately owned land. The access points should be sited within public areas with access availability at all times.

6.3 Detailed Design and Approvals

6.3.1 The drainage strategy is subject to approval from the EA and TWU if any elements are offered for adoption.

6.3.2 During detailed design stage, and if any elements of the drainage systems are offered for adoption, discharge rates and connections will need to be approved by TWU via a Section 106 Agreement for a direct connection to the public sewer. All sewers within the site and the off-site connection to the public sewer will be subject to adoption by TWU under a Section 104 Agreement.

6.3.3 Proposed drainage systems will need to be modelled in MicroDrainage to confirm required pipe sizes and storage volumes. This detailed modelling is required to confirm that the proposed drainage systems do not increase flood risk within and around the site.

6.3.4 Overland flow routes within the site will be considered and final external levels should be designed to prevent overland flow routes from entering buildings during extreme rainfall events.

Ref: ST2331/FRA-1408-Foster Street Page | 18 Flood Risk Assessment Foster Street, Harlow

7.0 Potential Sources of Flooding

7.1 Flooding from Rivers or Sea

7.1.1 Excluding the levels associated with drainage ditches, the lowest recorded levels on the Foster Street North and Foster Street South sites are 95.86m AOD and 96.80m AOD respectively.

7.1.2 The Indicative Floodplain Map, shown in Figure 1.1, identifies that the site is located within Flood Zone 1.

7.1.3 The primary source of fluvial flooding on the site would be from Shonks Brook from the south, or the tributary of this watercourse which runs along the southern boundary of the site. However, the EA flood maps indicate that fluvial flooding will not occur from the tributary but rather from Shonks Brook itself at a distance of approximately 860m from the site.

7.1.4 Interrogation of the EA floodplain maps identifies that the extent of flooding associated with the closest section of Shonks Brook, to the south east of the site, reaches up to a level of approximately 70m AOD. The lowest recorded level within the site was 95.86m AOD. Therefore, the site is not considered to be at risk of flooding from fluvial sources.

7.1.5 As the site is located inland, there is no risk of flooding from the sea.

7.2 Flooding from Land

7.2.1 Flooding from land occurs when intense rainfall is unable to soak into the ground or enter drainage systems. Local topography and built form can have a strong influence on the direction and depth of flow.

7.2.2 The SFRA identifies that there have been no recorded historical surface water flooding events in the vicinity of the site. It did note that surface water flooding usually occurred within the urban areas of the district and that the lack of maintenance of drainage systems was recognised as contributing to this problem.

7.2.3 The EA Indicative Flood Maps indicate that the south east corner of the Foster Street North site and an area in the centre of the Foster Street South site are at a potential risk of surface water flooding along the line of natural drainage routes. TWU have also confirmed that the area in the vicinity of the site has a history of surface water flooding due to the relatively flat topography, heavy clay soils and lack of well-maintained ditches and watercourses.

Ref: ST2331/FRA-1408-Foster Street Page | 19 Flood Risk Assessment Foster Street, Harlow

7.2.4 Overland flow paths will be taken into account in design of levels for the proposed development. Proposed external levels at entrances into the building should generally fall away from the building or fall towards gullies. Natural drainage routes will be provided towards surrounding ditches to avoid the risk of surface water flooding.

7.2.5 In order to reduce incidents of flooding on the adjacent highway, the silted up grips between the road and existing ditches will be reinstated by the developer.

7.2.6 On-site drainage systems will be designed to accommodate runoff volume from a 1 in 100 year storm plus 30% Climate Change rainfall event. The proposed attenuation features are proposed to accommodate runoff from roads, car parking areas and roofs, and proposed outfalls to the adjacent drainage ditches will discharge at a rate which provides betterment over the existing greenfield runoff.

7.2.7 Drainage systems will be designed in accordance with Building Regulations and connection to the public sewer agreed with TWU where appropriate.

7.3 Flooding from Groundwater

7.3.1 Groundwater flooding occurs when water levels in the ground rise above surface elevations. Groundwater flooding events are most likely to occur in low lying areas underlain by permeable rocks.

7.3.2 As previously stated, borehole log data obtained from the BGS website for the area in the vicinity of the site has identified that the site is underlain by London Clay. In addition, the borehole data identified a water table to a depth of approximately 3.6m below ground surface level for the two nearest boreholes to the site.

7.3.3 The SFRA identified that groundwater flooding is not an issue within Harlow, and there has been no historical recorded groundwater flooding events within the vicinity of the site.

7.3.4 Based upon the information above, it is anticipated that groundwater flooding should not be an issue to the proposed development. However, overland flow routes will be taken into account in the design of levels for the proposed development and, should groundwater flooding occur on the site, flows will tend to be intercepted by the proposed SuDS features throughout the developments.

Ref: ST2331/FRA-1408-Foster Street Page | 20 Flood Risk Assessment Foster Street, Harlow

7.4 Flooding from Sewers

7.4.1 The SFRA has identified that there has been no historical recorded flooding events which can be related to sewers within the vicinity of the site.

7.4.2 An impact study carried out by TWU identified that they have no records of any historical flooding clusters associated with the public sewer network in the vicinity of the development, although off-site works are being considered by TWU to increase the capacity of their downstream foul sewer network.

7.4.3 The development layout will be designed with consideration of flood routing, to ensure that new dwellings and occupants of the site will not be subject to detrimental impacts in the event of flooding from infrastructure failure within or upstream of the site.

7.5 Flooding from Reservoirs, Canals and Other Artificial Sources

7.5.1 No non-natural or artificial sources of flooding, including reservoirs, canals and lakes where water is retained above natural ground level, operational and redundant industrial processes including mining, quarrying and sand and gravel extraction, are located in the vicinity of the site which may cause increased floodwater depths or velocities.

Ref: ST2331/FRA-1408-Foster Street Page | 21 Flood Risk Assessment Foster Street, Harlow

8.0 Summary and Recommendations

8.1 Stomor Ltd. has been commissioned by C J Pryor Ltd and Anderson Design and Build to prepare a Flood Risk Assessment (FRA) associated with proposed development at land on Foster Street, Harlow.

8.2 The sites are located in the hamlet of Foster Street, to the east of Harlow and the M11.

8.3 The proposed development is to be split across two sites which are located on the north and south sides of Foster Street; Foster Street North site, on the north of the road, and Foster Street South site, on the south side of the road. The Foster Street South site covers a total area of approximately 2.7ha and comprises two parcels of land; the operational brownfield western part and the greenfield eastern part. The Foster Street North site covers an area of approximately 0.57ha and is brownfield.

8.4 For the purposes of this assessment, development proposals of up to 16 residential units on Foster Street North site and up to 69 residential units on the Foster Street South site are to be considered.

8.5 The nearest watercourse to the sites is Shonks Brook located approximately 860m south. However, the EA Indicative Flood Maps indicate that a tributary for Shonks Brook runs along the southern side of the Foster Street South site and connects to Shonks Brook near the junction between Mill Street and Hastingwood Road. Shonks Brook runs from the M11 towards the south east to connect to Crispey Brook which in turn connects to the River Roding in Chipping Ongar.

8.6 There are drainage ditches currently in place along the northern, southern and eastern boundaries of the Foster Street South site. Drainage ditches are also in place along the northern and north eastern boundaries of the Foster Street North site, as well as within the south west corner of the site.

8.7 Inspection of the British Geological Survey (BGS) website indicates that the underlying ground condition of both of the sites generally comprises London Clay overlain by silty clay with chalk fragments. Therefore, it is likely that the use of infiltration as a sole method for discharging surface water would not be suitable.

8.8 Thames Water Utilities (TWU) sewer records have identified that there are no public surface water sewers in the vicinity of the site. A 150mm diameter public foul water sewer runs towards the east along Foster Street to a foul pumping station located at the junction between Foster Street and Green Lane. From here, an 80mm diameter rising

Ref: ST2331/FRA-1408-Foster Street Page | 22 Flood Risk Assessment Foster Street, Harlow

main runs westbound along Foster Street to connect into a 100mm diameter rising main where Foster Street turns into Harlow Common, which in turn discharges into a 225mm diameter public foul water sewer on the west side of the M11.

8.9 Enquiries carried out with the EA have confirmed that a discharge rate of 5l/s from the Foster Street North site and a rate equivalent to greenfield runoff from the Foster Street South site would be suitable into the respective adjacent drainage ditches. Epping Forest District Council has advised that the drainage strategies should provide betterment compared to existing greenfield runoff rates.

8.10 Proposed drainage strategies for surface water have been prepared to identify potential SuDS measures which are considered feasible across the development sites. The strategy also demonstrates a proposed layout of flow control and attenuation features to enable maximum overall discharge rates of 5l/s and 10l/s during the 1 in 100 year storm event for the Foster Street North and Foster Street South sites respectively, with provision of sufficient storage to avoid flooding within the site during the 1 in 100 year + 30% Climate Change event.

8.11 The indicative drainage strategies incorporate a variety of SuDS features including:

Foster Street North

i. Lined porous paving within private parking areas are to be considered, where appropriate, to control runoff at source and treat surface water runoff within the site. ii. Provision of a detention basin located in the south of the site to treat runoff from areas in the south of the site while also providing storage for all storm events up to and including the 1 in 100 year storm event + 30% allowance for Climate Change. iii. 450mm diameter pipework to transport water between the detention pond and outfall, while also providing additional storage volume for attenuation.

Foster Street South

Ref: ST2331/FRA-1408-Foster Street Page | 23 Flood Risk Assessment Foster Street, Harlow

iii. Provision of 450mm diameter storage tanks and cellular storage under the internal road network, where appropriate, to provide storage for the more frequent storm events.

8.12 The proposed SuDS solutions will need to have clear, enforceable maintenance regimes in place so that they provide effective flood protection and water treatment for the long term.

8.13 Enquiries carried out with TWU identified that the Foster Street foul water pump station is unlikely to be able to cope with the additional flows from the development without upgrades to the foul water pump station and lengths of infrastructure downstream of this. A Section 98 application was subsequently submitted to determine the scope and cost of works associated with upgrading the public sewer network. In their response, TWU have confirmed a project estimate of £453,600.00 to upgrade their system as required, with a developer contribution of £370,559.00.

8.14 Indicative Drainage Strategies for the discharge of foul water from the Foster Street North and Foster Street South sites have been prepared and identify the following:

Foster Street North

ii. The strategy identifies a gravity connection to the 150mm diameter foul water sewer in Foster Street, with a proposed new manhole connection downstream of existing MH 8001.

Foster Street South

ii. Foul flows from the development will drain to a pump station located in the north western corner of the site. From here, flows will be pumped to the public foul water sewer in Foster Street with a connection at MH 7901.

8.15 During detailed design stage, the foul water connections to the public sewer will need to be approved by TWU. Proposed foul and surface water drainage systems will need to be modelled in MicroDrainage to confirm required pipe sizes and storage volumes.

8.16 The drainage strategy is subject to approval from the Environment Agency (EA).

8.17 The indicative floodplain map obtained from the EA website shows that the sites lie within Flood Zone 1, with a low probability of flooding. The primary source of fluvial flooding on the site would be from Shonks Brook. However, the extent of flooding associated with Shonks Brook is unlikely to affect the site.

Ref: ST2331/FRA-1408-Foster Street Page | 24 Flood Risk Assessment Foster Street, Harlow

8.18 The EA indicative flood maps, as well as discussions with TWU, have identified that both sites are potentially at risk of surface water flooding along the line of natural drainage routes.

8.19 Overland flow paths will be taken into account in design of levels for the proposed development. Proposed external levels at entrances into the building should generally fall away from the building or fall towards gullies.

8.20 Other potential sources of flooding including from groundwater, sewers and artificial sources are considered unlikely to affect the site.

Ref: ST2331/FRA-1408-Foster Street Page | 25 APPENDIX A

CHELSEA GARDENS

93 120

110 All Saints Cottage

124 SHOE LANE 101

111 Threeways 105 Path (um) GP

104 86

94.5m 70

118 65

122 61

DAVENPORT 81

39 55

80 Grave Yard

47 50

Foster Street Home Straight 19 Wain End 26 Cottages STREET

39 Cottage 1 27 30 32 34 20

M 11 FOSTER 24 2

56 51

14 Potter's Cottage CR

96.3m GREEN

M11 Old Farm

CP & ED Bdy 47 46 Foster Street Cottages 75 62 96.3m

LANE

154 155 Foster Street

Pond 2 1 TCB 144 Pond 149 Amber Cottage

MALKIN DRIVE 73 Foster Street

96.6m Ivydene

143 150 140 Northdene Farm Site May's Wish

139 160 Pond Foster Street Jubilee

Farm 67

68 94 El Sub Sta

133 165 Kenris

The Willows

Drain

STREET Bramleys

97 129

FOSTER

170 Drain

Drain

108

123 Drain 175

109 The Rigg 97.5m Foster's Croft Catkins Cottage Pond Thatched MALKIN DRIVE Tinkers Drain Cottage

Rose Cottage 1

118 Primrose Cottage 3 181 113

Cottages Sunnyside

1 The Lotus

190 Travellers Croft 186 Oak Cottage Cottages Cottage Cecil House

CR El Sub Sta Depot Works CB

Searles Farm Und Drain Hoggs Mast FOSTER STREET Farm Foster Street

95.4m Drain

Cattle Grid Cecil House Site

Dorsley House Rev Description Date Drawn Checked Revisions Pond Registered Office: 32 Beehive Lane, Welwyn Garden City, Hertfordshire, AL7 4BQ

Design Office: Drain Track 19 Walsworth Road, Hitchin, Herts, SG4 9SP Pond Tel 01462 615433 Fax 01462 615425 Email [email protected] www.stomor.com

LB Drain Project 99.1m Harlow, Foster Street Ponds The Horns and Horseshoes(PH) Track

CP & ED Bdy Cattle Grid Drawing Description Pond 98.5m Drain CF Brent House Site Location Plan HARLOW COMMON Harlow Common Farm Pig and Poultry Houses Und The Links

Scale Date Drawn By Checked By Pond Greenways 1:2500@A3 10.02.14 BID DGS Drain Pond Client Architect Track

Crabbs Farm

Notes Drawing Number Mill Street Do not scale off the drawing. Only written dimensions should be taken. Any discrepancies or errors should be brought ST-2331-20 to the attention of the engineer immediately. APPENDIX B

Asset Location Search Sewer Map - ALS/ALS Standard/2013_2505474 TL4808NE

50 ? 1 ?

ain

Dr ? ? 80

The Rigg 97.5m Foster's ?

7901 ? Croft ! ? Pond

a Ti nke rs ? T tk

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o a g t l 0 ? tt le 5 k e

a r 1 Cecil House s

g s C e ? o

t % t ? a

e ? ? Works

Depot 6901 ?

? ? Searles Farm n

ai r ? D

T E ? E Mast R 0

T 5 S 1 ? ER

T % 0 S ? 8

? ?

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i n

6801! ?

? Cattle Grid ?

? Dorsley House

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Pig and Poultry Houses 5701!

Greenways

% 1 5 0

5601 ! % 0 15

! 5501 150

in a r D

Waterlees

Works

T ra c k

The width of the displayed area is 500m and the centre of the map is located at OS coordinates 548750,208750 The position of the apparatus shown on this plan is given without obligation and warranty, and the accuracy cannot be guaranteed. Service pipes are not shown but their presence should be anticipated. No liability of any kind whatsoever is accepted by Thames Water for any error or omission. The actual position of mains and services must be verified and established on site before any works are undertaken.

Based on the Ordnance Survey Map with the Sanction of the controller of H.M. Stationery Office, License no. WU298557 Crown Copyright Reserved.

Page 7 of 14

NB. Levels quoted in metres Ordnance Newlyn Datum. The value -9999.00 indicates that no survey information is available

Manhole Reference Manhole Cover Level Manhole Invert Level 5501 n/a n/a 5601 97.82 96.42 5701 98.42 97.1 6801 98.6 97.56 6901 97.72 96.65 7902 97.64 96.03 - - - 7901 97.48 95.46

The position of the apparatus shown on this plan is given without obligation and warranty, and the accuracy cannot be guaranteed. Service pipes are not shown but their presence should be anticipated. No liability of any kind whatsoever is accepted by Thames Water for any error or omission. The actual position of mains and services must be verified and established on site before any works are undertaken.

Page 8 of 14

Asset Location Search Sewer Map - ALS/ALS Standard/2013_2505474 TL4809SE

R C y d B

D E

P C

1 1

S H

L A N ) E um ( th Pa

9103 ! !

Potter 's Cotta

O C ld

o F

tt a a ? Foster Street ge r 0 m 15 s

% ? 9102 ?

! 9101

Pond 2 TCB! ? ? ? 1 ?

Am ber

? Cottage ? 96.6m

0 ?

1 ? Pond Foster Street J

% u

0 b ??? 8 i Farm le e

El Sub Sta ?

K 8001 ? e 2 ! T nr h i e s ? 1 W T i in E ll ra RE B o D ? r ws T a S m ER ST le

8002 y O ? F ! s

15 ?

rain % ? D ? 0

in 8 8003ra ?

D! ?

? The width of the displayed area is 500m and the centre of the map is located at OS coordinates 548750,2092500 The position of the apparatus shown on this plan is given without obligation and warranty, and the accuracy cannot be guaranteed. Service pipes are not shown but their presence should be anticipated. No liability of any kind whatsoever is accepted by Thames Water for any error or omission. The actual position of mains and services must be verified and established on site before any works are undertaken.

Based on the Ordnance Survey Map with the Sanction of the controller of H.M. Stationery Office, License no. WU298557 Crown Copyright Reserved.

Page 9 of 14

NB. Levels quoted in metres Ordnance Newlyn Datum. The value -9999.00 indicates that no survey information is available

Manhole Reference Manhole Cover Level Manhole Invert Level 8003 n/a n/a 8001 n/a n/a 8002 97.26 94.22 9102 96.45 93.4 9101 96.43 93.3 - - - 9103 96.25 95.18

Page 10 of 14

ALS Sewer Map Key

Public Sewer Types (Operated & Maintained by Thames Water) Sewer Fittings Other Symbols A feature in a sewer that does not affect the flow in the pipe. Example: a vent Symbols used on maps which do not fall under other general categories Foul: A sewer designed to convey waste water from domestic and is a fitting as the function of a vent is to release excess gas. / Public/Private Pumping Station industrial sources to a treatment works. Air Valve Change of characteristic indicator (C.O.C.I.) Surface Water: A sewer designed to convey surface water (e.g. rain Dam Chase water from roofs, yards and car parks) to rivers or watercourses. Invert Level Fitting Summit

M Meter Combined: A sewer designed to convey both waste water and surface water from domestic and industrial sources to a treatment works. Areas Vent Column Lines denoting areas of underground surveys, etc. Trunk Surface Water Trunk Foul Operational Controls Agreement A feature in a sewer that changes or diverts the flow in the sewer. Example: A hydrobrake limits the flow passing downstream. Operational Site Storm Relief Trunk Combined Control Valve Chamber PPVent Pipe Bio-solids (Sludge) Drop Pipe Tunnel Ancillary

Proposed Thames Surface Proposed Thames Water Weir Conduit Bridge Water Sewer Foul Sewer

Gallery Foul Rising Main End Items Other Sewer Types (Not Operated or Maintained by Thames Water) End symbols appear at the start or end of a sewer pipe. Examples: an Undefined End at the start of a sewer indicates that Thames Water has no Foul Sewer Surface Water Sewer Surface Water Rising Combined Rising Main knowledge of the position of the sewer upstream of that symbol, Outfall on a Main surface water sewer indicates that the pipe discharges into a stream or river. Combined Sewer Gulley Proposed Thames Water Sludge Rising Main Rising Main Outfall W Culverted Watercourse Proposed

Vacuum Undefined End Abandoned Sewer Inlet

Notes: 1) All levels associated with the plans are to Ordnance Datum Newlyn. 6) The text appearing alongside a sewer line indicates the internal diameter of 2) All measurements on the plans are metric. the pipe in milimetres. Text next to a manhole indicates the manhole reference number and should not be taken as a measurement. If you are 3) Arrows (on gravity fed sewers) or flecks (on rising mains) indicate direction of unsure about any text or symbology present on the plan, please contact a flow. member of Property Insight on 0845 070 9148. 4) Most private pipes are not shown on our plans, as in the past, this information has not been recorded. 5) ‘na’ or ‘0’ on a manhole level indicates that data is unavailable.

Page 11 of 14

APPENDIX C

ST 2321 Harlow Foster Street Project Name Harlow Date 11th July 2013

Greenfield Runoff Calculation Based upon The SuDS Manual C697 and EA/Defra Technical Report W5-074/A

Site Area: 2.71 ha Soil Type SPR SAAR 600 mm 1 0.1 Soil Type 3 2 0.3 SPR (see table) 0.37 3 0.37 Hydrological Area 6 4 0.47 5 1

Use Area = 0.5km² for calculation

QBARrural 1.08 x 0.54 x 1780.1 x 0.1156 = 119.93 l/s for 50ha site = 2.3987 l/s/ha

From Growth Curves obtained from DEFRA report (see tabs)

Q1 QBARrural x 0.85 = 2.04 l/s/ha Q30 QBARrural x 2.20 = 5.28 l/s/ha Q100 QBARrural x 3.15 = 7.56 l/s/ha

For site specific flows

Q1 2.038875 x 2.71 = 5.53 l/s Q30 5.277089 x 2.71 = 14.30 l/s Q100 7.555832 x 2.71 = 20.48 l/s ST 2321 Harlow, Foster Street Project Name Harlow Date 11th July 2013

Greenfield Runoff Calculation Based upon The SuDS Manual C697 and EA/Defra Technical Report W5-074/A

Site Area: 0.57 ha Soil Type SPR SAAR 600 mm 1 0.1 Soil Type 3 2 0.3 SPR (see table) 0.37 3 0.37 Hydrological Area 6 4 0.47 5 1

Use Area = 0.5km² for calculation

QBARrural 1.08 x 0.54 x 1780.1 x 0.1156 = 119.93 l/s for 50ha site = 2.3987 l/s/ha

From Growth Curves obtained from DEFRA report (see tabs)

Q1 QBARrural x 0.85 = 2.04 l/s/ha Q30 QBARrural x 2.20 = 5.28 l/s/ha Q100 QBARrural x 3.15 = 7.56 l/s/ha

For site specific flows

Q1 2.038875 x 0.57 = 1.16 l/s Q30 5.277089 x 0.57 = 3.01 l/s Q100 7.555832 x 0.57 = 4.31 l/s APPENDIX D

FWS

FWS FWS LEGEND FWS

FWS

FWS EXISTING PUBLIC FOUL WATER SEWER FWS

FWS FWS EXISTING FOUL RISING MAIN FWS

FWS

FWS EXISTING DITCH

FWS

FWS PROPOSED FOUL WATER SEWER

FWS FWS PROPOSED FOUL RISING MAIN FWS

MH 7901 FWS IL 95.46 FWS PROPOSED PRIVATE FOUL WATER SEWER FWS

FWS PROPOSED PRIVATE SURFACE WATER SEWER FWS

FWS DRAINAGE CHANNEL FWS

FWS

FWS PROPOSED CELLULAR CRATES

FWS

FWS PROPOSED SWALE or SHALLOW DEPRESSION FWS

FWS

FWS PROPOSED GROUND LEVELS, BUILD UP FWS XXXXX

FWS AND FLOOD ROUTING INFORMATION

FWS Site Area = 2.71ha FWS Impermeable Area = 1.7ha (approx) MH 7902 FWS IL 96.03 FWS Discharge Rate = 10l/s IL 97.67 FWS Storage required for 1 in 100 year + 30% Climate Change event = Pò (approx) FWS Maximum Water Level = 97.80m FWS IL 96.08 FWS (150mm freeboard to lowest cover level of 97.95m)

FWS

1/110 FWS FFL 98.35

FWS

FWS -01-

FWS POROUS PAVING Storage Provided in Indicative Drainage Strategy:

-02- FWS 2Bed_A $5($ Pð IL 97.365 EX 880837 EFFECTIVE DEPTH = 300mm

FLOOD -03- 2Bed_A VOID RATIO 30% FFL 98.35 +200mm POROUS PAVING IL 97.14 ROUTE 92/80( Pñ v

FWS $5($ Pð 2Bed_A Swales: Pñ 3Bed_B2-04- EFFECTIVE DEPTH = 300mm FWS FFL 98.35 01p 23p VOID RATIO 30% Cellular Crates: 125m x 2.0 x 0.5 x 0.95 Pñ FWS 92/80( Pñ 18p FWS IL 97.09 22p 3Bed_B2-05- +200mm 01p PP3LSHV 280m x 0.159 Pñ

FWS 03p 18g 17p

02p 21p Porous Paving: Pñ FWS 03p

Build3Bed_A3 Up 150mm Car Park Level 98.35 04p 17p FWS 02p IL 97.95 20p 7RWDO Pñ

Allocated space for FWS -06- 04p +100mm

sub-station and pumping LINED POROUS PAVING TO Existing station parking and access. 15p

05p -17- PROVIDE 2 LEVELS OF 20p FWS OVERFLOW

Pumping

Building WATER TREATMENT: +200mm

06p v -16- 3Bed_B1 16p

FWS INTERCEPT RUNOFF FROM Plus higher level storage within porous paving to be controlled at source: MH 6901 StationPUMP 1/450 2Bed_A1 -18-

Ground Level 98.20 STATION LINED POROUS PAVING TO ADJACENT BUILDINGS -15- bins

FWS PROVIDE SOURCE IL 96.65 Build Up 240mm 2Bed_A1

CONTROL AND 2 LEVELS11p IL 97.58 22p PñPñPñPñ Pñ

FWS Cover to pipe = 660mm OUTLET 14g

OF WATER TREATMENT 2Bed_A1 sub ACO 13g IL 97.035 IL 97.41 12p 21p st. 3Bed_A1 19g FFL 98.55 -07- FWS IL 97.27 07p IL 97.35 3Bed_B2 FFL 98.55 19g FWS

Road Level 98.40 -13- -14-

06g 08p 14p

FWS Build Up 250-350mm -12- 1/450 13p KERB DRAINAGE (BEANY BLOCK OR 2Bed_A1 OUTLET 97.70

SIMILAR) MAY BE REQUIRED TO KEEP Cover to05g pipe = 855mm v FWS (concrete protection required) 2Bed_A1 ROAD RUNOFF AT HIGH LEVEL

-08- 3Bed_A1 FWS FFL 98.50

07g 16p -19- IL 97.02 3Bed_B2 FWS 08g 3Bed_B1

V -11- 15p

FWS 09g 2Bed_A1 10g IL 96.80 -20- FWS 09g

FWS FLOOD Road Level 98.4 2Bed_A1 FWS Cover to Pipe 1110mm

3Bed_C1ROUTE -21-

-10- 10g FWS IL 96.85 IL 97.15 -09- IL 97.075

FWS 12p 2Bed_A1 3Bed_C1 45p -22-

FWS 11p 21p

FWS FFL 98.80 2Bed_A1 IL 97.22 46p FWS -23-IL 97.69

CELLULAR CRATES 2m x 0.5m 1in500 (min 700mm cover)

1in450 FWS 22p

FWS FFL 98.50 3Bed_A1 FFL 98.35 -24-

3Bed_C1 24g -45- 23p EXTENT OF EXISTING

24p 25g DITCH TO BE CONFIRMED 46g BY SURVEY 3Bed_B2 25p

IL 96.94

47g -46- IL 97.42 26g -44- 26p

3Bed_C1 IL 97.06 3Bed_C1 bins

Road Level 98.62 -47- 47g LOCATION AND EXTENT

Build Up 50-250mm OF EXISTING DITCH TO BE -25- CONFIRMED BY SURVEY

Cover to pipe = 1200mm 45g SWALE - EFFECTIVE STORAGE AREA

-43- IL 96.85 7:/ P$5($ 3Bed_B1 Pð

v %(' $5($ Pð

Road Level 98.20 44g 3Bed_B2 ())(&7,9(92/80( DSSUR[Pñ

Build Up 70-120mm -48- 3Bed_A1 Cover to pipe 900mm 44g

(concrete protection required) -26- 3Bed_C1

51g 43g FLOOD ROUTE v REQUIRED FFL 98.30 3Bed_A1

48g 43g -42- -27- 49p

48pRoad Level 98.52 4Bed_B1 EX 736882 Build Up 100mm 42g SWALE

Cover to pipe = 1200mm 41p CHANNEL 27p

-49- 97.1 42g

1/450 41g MOVE THIS PART OF -28- 3Bed_B2 5Bed_B1

3Bed_B3 50g -34- DEVELOPMENT TO WEST

27p 3Bed_B2 TO ALLOW BUILD UP

-65- IL 96.87 3Bed_A1 28g 5Bed_A1

-41- 65g -33-

-50- IL 97.10 65g FLOOD ROUTES

28p

62g 4Bed_A1 29g FFL 98.15

64p REQUIRED 40g

OUTLET 98.2 33g 50p 3Bed_A1 BETWEEN 29p 5Bed_A1 POROUS PAVING -51- 3Bed_C1 -32- $5($ Pð BUILDINGS-40- IL 96.65 POROUS PAVING

EFFECTIVE DEPTH = 300mm

63p $5($ Pð

VOID RATIO 30% 51g bins -29- EFFECTIVE DEPTH = 300mm

92/80( Pñ 32g

Road Level 98.10 33g VOID RATIO 30%

51p FFL 98.25

40g Cover to pipe 900mm 34g 92/80( Pñ

52g 4Bed_B1

-64- (concrete protection required)

62p 52p 34g FFL 98.75 FFL 3Bed_B1

IL 96.76 -52-

30g 32g

33p

64g 34p

EX 704932 & LEASEHOLD EX 8757963Bed_B1 63g V Strategy amended to suit latest layout 30g 35g A 06.08.14 SJB NJM

IL 61p IL 96.75 Rev Description Date Drawn Checked Road Level 98.10

97.98 30p 35g -30-

3Bed_A1 No Build Up 32p Road Level Revisions -63- Cover to pipe 890mm V 98.00 35p

(concrete protection required) 53p 4Bed_B1 (+350mm) -39-

60p Registered Office: Road Level 98.45 CELLULAR CRATES 2m x 0.5m 1in500 (min 700mm cover) LOCATION AND EXTENT

39p 3Bed_A2 Build Up 150-400mm 4Bed_B1 31g OF EXISTING DITCH TO BE 32 Beehive Lane, Welwyn Garden City, -62- Cover to pipe 1200mm V 1in450 CONFIRMED BY SURVEY Hertfordshire, AL7 4BQ 53g 39g SWALE - EFFECTIVE STORAGE AREA 53g 31g

v FLOOD ROUTE39g 7:/ P$5($ Pð Design Office: -53- &+$11(/ $5($ Pð 3Bed_A2 REQUIRED ())(&7,9(92/80(31p DSSUR[Pñ LINED POROUS PAVING TO 19 Walsworth Road, Hitchin, Herts, SG4 9SP

-61- FFL 98.60 PROVIDE-31- 2 LEVELS OF New Ditch IL = 96.125 4Bed_B1 FFL 98.15 Tel 01462 615433 Fax 01462 615425

WATER TREATMENT:

38p

INTERCEPT4Bed_B1 RUNOFF FROM Email [email protected] www.stomor.com 54g -38- 3Bed_A1 ADJACENT BUILDINGS

IL -60- 54g 4Bed_B1 5Bed_B1 97.65 38g -35- Project Road Level 98.10

No Build Up 54p 36p -59- 38g Cover to pipe 900mm 37g 97.85

-54- 96.85 36g

37p

3Bed_B2 IL 96.77

59g FLOOD ROUTE

4Bed_B1 37g 36g IL 97.07 56g OUTLET 97.35 Harlow, Foster Street

60g OUTLET 98.10 REQUIRED IL 97.34 FLOOD ROUTE 58p SWALE IL 97.29 4Bed_B1 REQUIRED CHANNEL POROUS PAVING 5Bed_B1 -56- 96.85 $5($ Pð -55- 1/1000

59p -37- EFFECTIVE DEPTH = 300mm 56g 1/1000

VOID RATIO 30% Drawing Description FFL 98.25 5Bed_B1 New Ditch IL = 96.10

1/450

92/80( Pñ 55g 55g

-58- 57p IL 96.85

IL 96.53 5Bed_B1 Indicative Drainage Strategy

56p

4Bed_B1 -36-

58g

57g 55p Parcel A 61g

Road Level 98.10 55p V 57g Cover to pipe 950mm V (+450mm) 97.80 97.80 CL 97.95 REGRADE DITCH AS NECESSARY TO ACHIEVE PROPOSED IL 96.51 Drawn By Checked By

96.85 SWALE INVERT LEVEL AT OUTFALL, WITH 1 IN 1000 FALL ALONG DITCH Scale Date -57- CHANNEL 96.85 IL 96.70 96.85 IL 96.85

4Bed_B1 INFILTRATION TRENCH IL 96.55 1:500@A1 07.01.14 NJM DGS LINKING SWALES New Ditch IL = 96.20 Flow Control 10l/s 300mm freeboard to incoming connection Client Architect REGRADE DITCH UPSTREAM OF OUTFALL TO PROVIDE Existing Freeboard MAX 1 in 40 GRADIENT TO PROPOSED INVERT LEVEL SWALE - EFFECTIVE STORAGE AREA 7:/ P$5($ Pð &+$11(/ $5($ Pð ())(&7,9(92/80( DSSUR[Pñ

SWALE - EFFECTIVE STORAGE AREA 7:/ P$5($ Pð New Ditch IL = 96.05 &+$11(/ $5($ Pð ())(&7,9(92/80( DSSUR[Pñ

Notes Drawing Do not scale off the drawing. Number Only written dimensions should be taken. New Ditch IL = 96.03 Any discrepancies or errors should be brought ST-2331-18-A to the attention of the engineer immediately. Bushes/Trees upto10h

B/W 1h

96.88 Electric Fence 1h Fence Electric 96.89 96.74 96.98 96.82 97.48

OHL Grass 96.61 97.03 96.63 95.91 96.67 96.61 96.77 96.45 97.07 97.60 96.77 96.85 96.64 96.19 97.40 Acer 10h 96.96 96.92 96.61 96.60 96.65 97.03 Acer 10h 97.35 96.71 Acer 10h 97.47 97.36 GG 96.85 Grass 96.63 96.03 97.36 97.11 96.81 96.65 96.85 97.34 96.33 Willow 12h 97.02 96.86 97.53 97.44 Acer 10h 96.75 96.92 97.08

96.05 548840.00mE 96.75 97.19 96.60 97.48 97.05 Ash Multi10h 97.51 96.89 FLow ControlChamber 5l/s maximumdischarge 97.09 97.19 96.84 Electric Fence 1h Arable Field Top ofTP105.04 TP B/W 1h 95.87

97.05 OHLs 97.53 97.38 95.17 96.82 96.47 Acer 10h 96.80 96.61 Ash 10h 96.88 96.64 97.51 97.57 97.54 Bushes/Trees upto10h Unable toSurveycontinuationofDitchdueDenseBushes 96.96

B/W 1h Grass 96.73 Top ofEP104.98 97.48 Arable Field 96.02 Bushes/Trees upto10h POSSIBLE FUTURE CONNECTION 95.69 97.05 EP 96.68 Container 96.12 95.10 96.79 94.28 97.57 96.30 Indicative ProposedIL=94.33 (300mm clearancetobedlevel of ditch) 96.73 96.94 96.82 96.16 97.01 96.85

96.15 95.24

95.91

Grass 96.47 OHLs Unable toSurveycontinuationofDitchdueDenseBushes Willow 12h 97.62 96.38 97.55 97.04 IL 95.73 96.38 97.30

96.68

Grass FWS 97.52 96.98

Electric Fence 1h Fence Electric UK 7h 97.00 94.52 IL

97.41 548860.00mE 96.81 UK 7h

95.98 96.33

FWS -8- 94.70 IL 96.83 97.27 CL 96.3min 97.06 97.13

97.12 (+0mm) Ash 12h 96.93 96.19 BU 97.55 96.26 96.36 Grass 96.22 97.73 95.22 Arable Field 97.16 Bushes 3h 97.22 96.41 96.83

FWS 96.07 97.11 97.41 Ash 12h 97.02 96.50 ST04 96.84 96.32 97.21 Top ofEP104.99 96.39

96.44 96.46 97.56 97.23 95.83 FWS 97.17 96.51 96.55 96.21 DP 97.09 97.54 96.35 97.47

Grass Acer 10h 97.19 -9-

97.08 96.11 96.89 Tank Acer 10h 2YHUIORZ 97.26 -7- EP 97.45 97.10 96.34 Grass 97.22 Acer 15h 97.50 97.17 97.11 97.48 Bushes/Trees upto10h 96.63 Gravel FWS Gravel Acer 10h 96.77 96.86 Grass 97.18 97.55 Asphalt

97.52 IL 95.99

3LSH OHLs 96.67 Gravel 97.11 Ash 12h 97.03 97.16 96.98 Gravel 97.43 97.53 96.82 FWS Ash 10h 97.52 97.06 97.05 96.71 97.06 96.71 96.84 97.18 96.79 Grass 96.16 DP IL 95.29min

IL 94.72 97.17 97.58

C/L 2h 96.90 97.51 96.79

97.07 OHLs 96.76

FWS 97.02

96.74 SI 97.06 2h C/L 97.55

95.28 96.34 97.49 97.57 96.79 Flat RoofLevel Sub-Station 96.75 No AccesstoSub-station 100.70 Top ofTP104.65

97.52 CL 96.20

BU 1.03m cover 3LSH

FWS Concrete 97.09 BO 96.77 DP 95.90 Area Locked to pipe 97.06

IL 96.57

97.09 EGL 95.9 TP 97.47

97.33 96.80 97.54 (+250mm) 3LSH -6- 97.13 94.96 IL 97.51 98.20 96.85 IL 96.57 BU 97.54 PO 97.11 Gravel FWS UK 8h 96.77 96.47 Grass 96.90 548880.00mE 95.52

96.78 Grass 97.06

Top ofEP105.36 Grass

EP 1/60 96.80 C/L 2h C/L 96.41 96.15 95.32 FWS 95.86

Foster Street 96.23 PO 97.10 PO

97.16

101.28

Asphalt 40 mph. Hawthorn 8h 97.06 97.39 EL 95.73 IL 95.69 96.75 96.80 Ash 10h Concrete Cladded Barn

97.30

97.48 LOCATION AND 96.24

96.78

97.41 DEPTH OF EXISTING

FWS PIPE TO BE DP protection Concrete

CONFIRMED 2YHUIORZ 96.76

97.38 97.40 97.03 96.34 97.06 94.42 IL 95.33 96.73 Bushes 5h 97.26 Bushes/Trees upto10h 96.82

FWS 96.50 96.82 Wall

SV Sett

96.36 97.38 97.43 94.62 Concrete Grass

MP -4- -5- C/L 1.8h C/L 95.98 Store 96.00 IL TBC MH 8001 94.06 Assumed Top ofRS99.60 97.50 Ash 10h FWS IL 96.03 97.35 96.80 Top ofSI99.88 SV SI(Pub.Path) 96.39 96.37 96.69

Store 104.76 95.45 95.33 97.21 96.55 96.43

97.28 97.48 RS 1/60 RL 96.83 97.31 Grass 96.85 96.67

FWSIL 96.44 98.71 EL 3LSH 96.36 94.71 96.87 97.04 IL 94.22 MH 8002 IL 96.30 97.14 -1- 96.79 96.91 96.61 96.85 PO

FWS 96.76 95.45

96.79

Gravel 96.48 Unable to Survey continuation of Ditch due to Dense Bushes Dense to due Ditch of continuation Survey to Unable 96.85 96.51

96.26 MP

Gravel

96.32 Land DrainageConsent required foranystructure within 8mofditch 96.50 IL 94.01 IL DP

Canopy of Store 96.70 Arable Field

FWS 95.50 96.74 PO UK 8h

IL 96.30 Grass 96.82 MP 96.71 96.63 Low levelvegetation

FWS Sheltered Store IL 95.3 Sapling

1/132 AV. FWS 97.24 Ash Multi8h

FWS 96.10 96.81

FWS FWS 97.38 102.30

FWS PO

96.22 under electricitycables.Alternative Drainage willneedtobeconstructed

FWS design dependentuponfinallayout. arrangements tobeconsideredatdetailed SAFETY NOTE: 96.98 1/150 96.35

UTL CL 97.37 IC EL FWS PO Long grass 97.40

96.69 IL94.93

Grass 96.74 2YHUIORZ 96.72

96.30 548900.00mE 96.25 97.23 96.86 FWS LOCATION AND DEPTH OF ANY EXISTING -2- 96.07 CL 96.7 96.15

DRAINAGE IN THIS AREA TO BE IDENTIFIED PO (+0mm) 95.64

IL 96.25 Grass

96.06 96.41

Acers 6h

FWS 95.28 IL UTL (Bolteddown) CL 96.77 MH BU

FB Canopy of Store of Canopy PO Container 96.81 96.11 99.09 PO Grass EL UK 6h Bushes/Trees upto10h PO 97.28 PO 97.15 96.04 96.06 96.04

FWS 96.56 96.09 96.32 96.44 96.09 PO 96.11 96.05

ST03

96.43 96.95 96.43 96.12 FB

96.90 95.82 97.29 96.76

96.39

2YHUIORZ IL 93.90 IL Arable Field

BU FWS 96.73 96.09 Paved 96.05 Greenhouse 96.95 UC Flat RoofLevel 96.32 97.07 Brick Garage 97.00

102.10 99.57

RL 102.16 BU 96.97 -3- C/L 1.8h RL RL 96.29 99.13

96.37

Cladded Barn 96.68 FWS 96.61 95.10 IL 96.23 Willow 10h 96.18 97.43 96.19 97.15 97.05 96.36

100.78 IL 95.10 IL Grass

RL IL 95.20 IL 96.36 96.95

99.72 Gravel Willow 12h Area ofContainers C/L 1.8h C/L EL 96.19 97.20

FWS 98.87 98.41 DP EL EL 96.34 FB 97.17

96.22

96.17

Hedge 2h Hedge 1/150 96.20 Grass

FWS 96.12 96.80 96.33 96.86 Top ofTP105.11 96.12 96.77 97.33

96.51 96.67 Shed 96.65

96.77 Cladded Barn 96.25 96.36 Soffit Level DC 97.14 TP 96.90

FWS 96.24 97.06 96.78 96.53 209060.00mN 209100.00mN 96.72 Concrete 97.01 96.29 96.20 96.32 96.79 96.75 96.67 Gravel 209080.00mN

FWS Oil Tank 96.31 97.03 96.71 96.40 96.27

IL 95.93 96.25 96.57 FWS Grass

96.52

Impermeable Area=0.33ha(approx)plus0.02haallowancefor Maximum WaterLevel=96.10m Discharge Rate=5l/s (150mm freeboardtolowestcoverlevelof96.25m) = Storage requiredfor1in100year+30%ClimateChangeevent Site Area=0.55ha IL 93.76 IL future connectiontowest 96.19 UK 4h 96.41 WM 96.63 Picket 1.5h 548920.00mE

FWS 96.40 Pò

Wooden Arch 96.68 Hedge 2h 95.10 IL 96.00 3LSH 96.73 Gravel 96.20 96.68 FWS 96.31 SV 96.51 96.31

209020.00mN 209040.00mN 96.63 96.39 96.10 Private Garden 96.33 96.44 96.38 Picket 1h (approx)(or

FWS Gravel 96.31

96.44 96.68 1h Picket 96.37 96.52

96.05

96.49 GL 96.6 1.8h Pan 96.47 96.45

96.52 (+300mm) 96.30

96.47 96.34 FWS 1h Picket

96.37

Paved 96.31 Pan 1.2h Pan 96.49 DP 96.43 96.47 Rev 96.37 Notes Client Drawing Description A FWS Project FB DP Step Up EL 98.90 96.51 96.54 XXXXX 1:500@A3 96.22 KO 96.19 96.36 101.17 EL to theattentionof the engineerimmediately. Only writtendimensionsshouldbetaken. Do notscaleoffthedrawing.

Any discrepanciesorerrorsshould be brought 96.19 Description Strategy amendedtosuitlatestlayout

Concrete ())(&7,9(92/80( DSSUR[Pð BASIN -EFFECTIVESTORAGEAREA 287)$// P$5($Pð 7:/ P$5($Pð

96.55 96.40 IL Assumed93.71 FWS 1.8h Pan be divertedifnecessary. pipe tobeconfirmed.Existingdrainage Location ofpossibleexistingunderground

96.29 103.77 96.07 96.22 (+130mm) 96.50 Scale RL DP Gravel

FWS 96.45 96.09 Pò 96.47 LEGEND 2 StoreyCladdedDwelling 95.85 96.36 ST02 96.24 104.10 96.20 RL 96.50 Grass 106.00 RL WM Concrete 101.72 95.85 EL 95.75 101.31 SV 96.30

FWS 96.51 EL Indicative DrainageStrategy 2 StoreyCladdedDwelling ) 101.14 96.51 1/132 AV. EL 96.43 AND FLOODROUTINGINFORMATION PROPOSED GROUNDLEVELS,BUILDUP PROPOSED SWALEorSHALLOWDEPRESSION

PROPOSED CELLULARCRATES DRAINAGE CHANNEL

PROPOSED PRIVATE SURFACE WATER SEWER PROPOSED PRIVATEFOULWATERSEWER PROPOSED FOULRISINGMAIN PROPOSED FOULWATERSEWER EXISTING DITCH EXISTING FOULRISINGMAIN EXISTING PUBLICFOULWATERSEWER FWS 96.53 96.53 Harlow, FosterStreet Flat RoofLevel 06.01.14 106.07 DP 96.53 RL 99.66 96.58 96.22 548940.00mE

96.60

FWS 98.93 EL Date Wall 1h FB 96.27 99.86 RL 96.53 96.61 UC 96.35

FWS 96.52 Parcel B 96.57 96.61 UC FWS Private Gardens Revisions Grass 96.35 96.68 96.31 96.51

96.34 C/L 1h FWS Architect 96.12 96.56 Number Drawing 96.55 96.49

95.48 FWS 2h Hedge 96.22 CL 96.25 IC UTL (Bolteddown) 96.38 Drawn By 96.50 NJM Tel 01462615433Fax615425 19 WalsworthRoad,Hitchin,Herts,SG49SP 32 BeehiveLane,WelwynGardenCity, Email [email protected] Hertfordshire, AL74BQ MP 96.24 FWS 96.37 Foster Street 96.47 100.18 EL 96.31 96.37 96.43 Asphalt 40 mph. Gravel Grass 96.11 ST-2331-19-A OHANGWIL 7H FWS

95.58 96.44 96.31 Registered Office: 101.87 RL Design Office: 96.28 96.39 Grass 96.36 FWS 96.18 96.46 06.08.14 96.56 96.35

2 StoreyCladdedDwelling Wall 0.6h 96.49 Date 96.41 UC 96.47 Hedge 2h 96.33 FWS Asphalt 96.45

95.65 Checked By 96.31 96.48 DGS 96.37 GG Drawn 96.51 SJB 96.41 96.37 96.43

548960.00mE FWS Unmade Ground IL 93.40 MH 9102 H 96.54 96.37 FH Checked 96.50 NJM 96.60

96.52 FWS Bushes/Trees upto10h 96.55 APPENDIX E