17132 / Hero of Switzerland, 142 Loughborough Road, SW9 ...

17132 / Hero of Switzerland, 142 Loughborough Road, SW9 7LL

April 2019 / Basement Method Statement

Rev Date Description

- 25 March 2019 Submission for inclusion in planning application

A 08 April 2019 Updated to unify application material

B 16 April 2019 Updated to incorporate Scott White and Hookins’ Capacity Assessment

Prepared by: Robert Dean BEng (Hons) CEng MIStructE

Authorised by: Michael Hadi BEng (Hons) CEng MIStructE

Issued by: Robert Dean BEng (Hons) CEng MIStructE

Non-Technical Summary

This note is a Basement Method Statement (BMS), as requested by Lambeth Council’s pre-application advice letter

dated 5/6/17.

The existing public house property has three storeys, including a basement level that does not cover the full site

footprint.

It is proposed the existing building be demolished and replaced by a 13-storey building (plus basement, mezzanine

floor levels and roof level access), with residential accommodation at levels 1 to 12, public house at ground floor

and mezzanine levels, a full basement level and a roof garden.

The construction of the basement is feasible and will not have an adverse impact on flooding, surface flow,

groundwater flow, ground stability or adjacent structures.

A safe method and sequence of construction has been identified and is presented in this document.

17132 / Hero of Switzerland – Basement Method Statement 2

Contents

Summary

1 Introduction

3

2 The existing site and structure

3

3 Nearby structures

4

4 Proposed Development 4

5 (a) Detailed site-specific analysis of hydrological and geotechnical local ground conditions 5

6 (b) Analysis of how the excavation of the basement may impact on the water table and any

ground water, and whether water perched is present

5

7 (c) Details of how flood risk, including risk from groundwater and surface water flooding has

been addressed in the design, including details of any proposed mitigation measures

6

8 (d) Details of measures proposed to mitigate any risks in relation to land instability

6

9 (e) Demonstration of how cumulative effects have been considered 8

Appendix A – Potential Sequence of Basement Construction

Appendix B – Extracts from Soil Consultant’s site investigation report, dated September ‘18

Appendix C – Scott White and Hookins’ Flood Risk Assessment and Drainage Strategy,

dated April 2019

Appendix D – Scott White and Hookin’s Capacity Assessment


1.0 Introduction The existing public house property has three storeys, including a partial basement. It is proposed the existing building be demolished and replaced by a 13-storey building (plus basement, mezzanine floor levels and roof level access), with residential accommodation at levels 1 to 12, a public house at ground floor and mezzanine levels, a full basement level and a roof garden. The information contained in this note is based upon: - Lambeth Council’s pre-application advice letter dated 5/6/17 - Site visits - Gensler Architect’s drawings. - British Geological Survey Maps - Nicholas Barton’s book, The Lost Rivers of London - LCC Bomb Damage Maps, 1939-1945 - URS’ Lambeth’s Strategic Flood Risk Assessment report, dated March 2013 - Arup’s Lambeth Residential Basement Study, Report of Findings, dated April 2016 - Soil Consultant’s Site Investigation Report, dated September 2018 - Scott White and Hookins’ Flood Risk Assessment and Drainage Strategy, dated April 2019 - K2 Consultancy Ltd’s Demolition & Construction Management Plan, dated June 2018. - RPS’ Tree Survey Report, dated August 2018. This report has been prepared for the benefit of the Client and others can take no reliance without written agreement from Michael Hadi Associates Ltd. For ease of reference, the relevant text from Lambeth Council’s pre-application advice letter of 5/6/17 under the heading ‘Basement Construction and Flooding’ is pasted below: Policy EN5 seeks to minimise the impact of flooding in the borough. Basement proposals shall incorporate appropriate mitigation measures to ensure the development is safe from all forms of flooding and does not increase flood risk elsewhere. Paragraph 9.33 of the Local Plan requires applications to demonstrate that the proposal would not cause harm to the built and natural environment and local amenity and would not result in flooding or ground instability. As a basement is proposed, a Flood Risk Assessment (FRA) and a Basement Method Statement will be required with full application. The basement method statement, along with the FRA, must contain the following details: a) Detailed site specific analysis of hydrological and geotechnical local ground conditions; b) Analysis of how the excavation of the basement may impact on the water table and any ground

water, and whether water perched is present; c) Details of how flood risk, including risk from groundwater and surface water flooding has been

addressed in the design, including details of any proposed mitigation measures; d) Details of measures proposed to mitigate any risks in relation to land instability; e) Demonstration of how cumulative effects have been considered; f) A comprehensive non- technical summary document of the assessments provided and information

submitted against (a) to (e) of this condition.

2.0 The existing site and structure The property is located on Loughborough Road, with Featley Road at the rear of the site. We understand the public house was constructed during the 1960s and utilises load-bearing masonry walls with concrete ground and basement floors. The basement footprint is less than the footprint of the ground floor level over and the retaining walls are presumably formed from masonry. The existing site is relatively level with the pavement level at approximately 11m AOD, taken from Arena Property Services measured survey drawing. The London County Council (LCC) record WW2 bomb damage maps show the site having been hit by a V1 flying bomb and buildings on the site were damaged beyond repair (refer to appendix D of Soil Consultants’ report in Appendix B). Thames Water’s records do not show their sewers to be running under the site (see their records contained within Scott White and Hookins document in Appendix C).


UK Power Networks records provided by the M&E engineer show some two high voltage cable running across the grassed area to the northwest of the site, however indicative CAT scan tracing and the viewing of inspection chamber locations suggested the cables do not immediately abut the site. A Wild Cherry tree approximately 9m high (ref. RPS’ Tree Survey Report) is located approximately 3m from the northwest corner of the site. RPS’ report this tree to be in poor condition and recommend it be removed.

3.0 Nearby Structures There are three buildings near the proposed basement. These are: 150-160 Loughborough Road (including 1-9 Featley Road) – approximately 2m away from the southwest corner of the site. Post WW2 construction of three storeys, presumably without a basement. Leicester House – approximately 10m away to the north of the site. Large residential building of eleven storeys above ground. 10 Featley Road – approximately 11m away to the southwest of the site. Large residential four storey building, presumably constructed within the last 20 years.

4.0 Proposed Development It is proposed the 13-storey tower be formed from reinforced concrete, utilising flat slabs supported on columns and core walls. The core walls provide the lateral stability to the superstructure. The proposed single storey basement is to be formed from perimeter contiguous piles and is to utilise a piled raft slab. The basement construction is discussed in detail in section 8 (d) and on the drawing in Appendix A.

Indicative 3D image of the structure


5.0 (a) Detailed site-specific analysis of hydrological and geotechnical local ground conditions

Ground investigations were undertaken by Soil Consultants Ltd (SCL) and Appendix B contains relevant

extracts from their report dated September 2018. The full report can be provided upon request. The

team interpreting the site findings include a Chartered Geologist (CGeol) and a Chartered Civil Engineer

(MICE).

The geotechnical ground conditions are summarised in section 5.0 and the hydrological conditions in

Appendix E (written by a hydrogeologist) of SCL’s report.

The site investigations included a 12m deep borehole and trial pits. Made ground was found to a depth

of between 0.9m and 1.4m below ground level, over Taplow Gravel to a depth of 5.9m, over London

Clay. Ground water was encountered during drilling within the Taplow Gravel at a depth of 4.2m and

during subsequent monitoring at a depth of 3.95m in the standpipe.

British Geological Survey (BGS) records suggest the interface of the London Clay and the underlying

Lambeth Group is likely to be at a depth in excess of 25m below ground level.

Non-technical summary:

The geology determined during site investigation works was in line with the expected geology based on

published British Geological Survey records.

The ground water level was found to be at around a depth of 4m below ground level.

6.0 (b) Analysis of how the excavation of the basement may impact on the water table and any ground water, and whether water perched is present

The hydrogeological assessment contained in Appendix E of SCL’s report states ‘The gradient of the water table appears to be approximately northwards (towards the Thames) but the exact groundwater flow direction is unknown. Typically, if the system were to be modelled, and if the basement fully penetrated the sand and gravel aquifer, the rise in groundwater level might be expected to be no more than perhaps 0.4 m on the upstream edge. Since the proposed basement extends only a very small distance below the water table (relative to the full saturated thickness) this assumed rise will be a considerable over-estimate. There are no basements upstream of the proposed basement at the Hero of Switzerland. Hence, even if there was to be a change in groundwater level there is no basement to be affected. It is unfeasible to imagine that the groundwater level might rise above ground surface in these conditions (i.e. starting at around 4.0 m below ground).’

They conclude ‘There are no basements up hydraulic gradient from the basement so there is no risk to adjacent basements even if groundwater levels were to rise slightly as a result of basement construction.’


The ground water level was found to be at around a depth of 4m below ground level and it is assumed

the water flows northwards towards the Thames. The basement construction may cause the local

upstream ground water level to rise, but no more than 0.4m.

Adjacent basements were not observed in the vicinity of the site and there is no risk of the potential small

elevation in local ground water level effecting neighbouring buildings.


7.0 (c) Details of how flood risk, including risk from groundwater and surface water flooding has been addressed in the design, including details of any proposed mitigation measures

Flood risk has been assessed and addressed under Scott White and Hookins Flood Risk Assessment

and Drainage Strategy contained in Appendix C.

The site is located within the Environment Agency (EA) Flood Zone 1 defined as land assessed as having

a less than 1 in 1,000 annual probability of river or sea flooding (<0.1%) and is therefore considered to

be at low risk of flooding. No flood mitigation measures are deemed to be required.

Surface water runoff from the proposed roof and hard landscaped areas will be attenuated by the

provision of a cellular water storage crates located at the Loughborough Road side of the site, before

discharging into the existing combined sewer. There will be no overall increase in man-made

impermeable area and therefore the amount of surface water runoff will not be increased by the

development and no water will flow to ground directly.

Lambeth Council’s Surface Water Management Plan indicates that the site is not within a critical area

for surface water flooding.

Groundwater flooding has also been assessed by the hydrogeological assessment contained in

Appendix E of SCL’s report (in Appendix B) and stated there are no cited records of groundwater flooding

on or near to Loughborough Road.


The site is located within an area considered to be at low risk of flooding (zone 1). No flood mitigation

measures are deemed to be required.

It is anticipated that the works will not increase the risk of surface water flooding. All surface water will

be discharged to the existing sewer, via underground attenuation storage tanks that will restrict the water

discharge to the sewer system during an extreme rainfall event.

The development of the site will not increase the area of impermeable surfaces and all surface water will

be discharged to the existing sewer, via underground attenuation storage tanks.

There are no cited records of groundwater flooding on or near to Loughborough Road.

8.0 (d) Details of measures proposed to mitigate any risks in relation to land instability

Geological and land stability issues have been assessed and addressed within section 7.0 of Soil

Consultant Ltd’s Report (Appendix B) using an impact assessment approach.

SCL state that the risk to ground stability from this development should be relatively low and that further

groundwater monitoring should be undertaken prior to construction to verify levels, particularly during

wet periods, as this may have an impact on the construction methodology. The expected peak elevation

of the ground water level during winter maybe around 0.3m above the summer level observed in the

standpipe. If the ground water level were found to be elevated before construction, then a secant piled

wall could be used for the basement perimeter to seal the excavation from water ingress (a cofferdam).

SCL conclude that for the proposed basement construction, it should be possible to design the

construction methods to ensure that ground movements do not adversely affect either adjacent

properties or infrastructure.

It is proposed that the basement structure be formed with a perimeter contiguous piled wall and a piled

raft slab. The formation level is expected to be at a depth of around 4m below ground level.

The head of the retaining wall is to remain propped at all times, to provide a rigid construction to keep

ground movements to an acceptable minimum. Temporary props and a reinforced concrete capping

beam waler are to be used during construction until the ground floor slab has been cast and is sufficiently

cured.

The depth of the existing foundations to 15-160 Loughborough Road are not know, but an appropriate

surcharge pressure is to be accommodated in the retaining wall and propping design. This property

does not immediately abut the site.


A potential, appropriate and safe sequence of construction has been identified and is shown on MHA’s

drawing 10 in Appendix A. The final temporary works scheme will be developed by the chosen main

contractor. The text from the sequence is repeated below:

1. Carefully demolish the superstructure of the existing Public House, top-down and front

(Loughborough Road side) to back (Featley Road side). Contractor is to note the basement footprint

and take care to avoid high surcharges onto perimeter retaining walls. Suitable material can be

crushed and stored for use in the future piling mat.

2. Using suitably battered excavations, carefully demolish the retaining walls to the basement

perimeter and then remove the basement slab and grub-out foundations.

3. Partially infill or wholly infill basement excavation using demolition material (or suitably prop to

support ground floor construction). Form an appropriate piling mat for the chosen CFA rig, in

accordance with BRE470 ‘Working platforms for tracked plant’. The contractor may decide to infill

the basement excavation in sections, if they decide it is more economic to form the piling mat in

sections, rather than across the whole site (borrowing material from elsewhere but retaining an

appropriate batter to the perimeter). Or set-down at a slightly lower level the central part of the site

(again depending on the chosen piling rig and the slope it can safely travel down to reach the lower

level).

4. Install the perimeter contiguous piling. Following immediately behind the piling works form the

reinforced concrete perimeter (RC) capping beam.

5. Install sleeves and install the piling for the central part of the site, under the ‘core’ region (contractor

may elect to not sleeve and break- down the piles later).

6. Install full-width props (probably hydraulic) onto appropriate bearing spreader blocks set just below

the capping beam (so the props do not interfere with the construction of the ground floor slab).

7. Excavate to basement raft formation level. Material is to be removed via a suitable slope near the

front of the site.

8. Break-down central piles and construct basement raft slab. Raft slab is to be connected to the all

the perimeter contiguous piles.

9. Provide a reinforced concrete lining to the perimeter contiguous piled wall (to suit chosen water-

proofing strategy).

10. Construct reinforced concrete walls and columns to underside of ground floor slab.

11. Construct the ground floor slab.

12. Once sufficiently cured, remove the props.

13. Construct and complete the superstructure.

14. Excavate and construct the external rainwater attenuation tank and rainwater booster set at the front

of the building. Prior to this, this site area can be used for the storage of materials and for welfare

facilities (& possibly a tower crane).


The risk to ground stability due to this proposed development should be low.

A safe and appropriate potential sequence of construction has been presented.


9.0 (e) Demonstration of how cumulative effects have been considered

There are no known existing basements in the vicinity of the site, thus cumulative effects are deemed to

be insignificant.

In terms of groundwater flow, Arup’s Residential Basement Study, Report of Findings, dated April 2016,

for Lambeth states ‘A solitary, isolated basement which intersects the groundwater table is unlikely to affect the groundwater flows in the wider area: the water will simply flow around the obstruction. The effects on water level are likely to be small and less significant than seasonal or other existing variations in the groundwater table.’

The hydrogeological assessment in Appendix E of Soil Consultant Ltd’s report (contained in Appendix

B) states ‘Typically, if the system were to be modelled, and if the basement fully penetrated the sand and gravel aquifer, the rise in groundwater level might be expected to be no more than perhaps 0.4 m on the upstream edge. Since the proposed basement extends only a very small distance below the water table (relative to the full saturated thickness) this assumed rise will be a considerable over-estimate. There are no basements upstream of the proposed basement at the Hero of Switzerland. Hence, even if there was to be a change in groundwater level there is no basement to be affected.’


The cumulative effects of multiple adjacent basements are not applicable, as there are no known

basements in the vicinity.

It should also be noted that an existing basement exists on the site, it is just being enlarged.


Appendix A – Potential Sequence of Basement Construction MHA’s drawing 10

SITE BOUNDARY

LEICESTER HOUSE

150-160 LOUGHBOROUGH ROAD

DEMOLISH EXG. BASEMENT RETAINING WALLS AFTER BATTERING EXCAVATIONS.

10 FEATLEY ROAD

SITE BOUNDARY

PERIMETER CONTIGUOUS PILING INSTALLED.

LEICESTER HOUSE


SITE BOUNDARY

LEICESTER HOUSE


SITE BOUNDARY

7

DENOTES PROPPING.

EXCAVATE TO BASEMENT RAFT LEVEL.

LEICESTER HOUSE


PILING, PROPPING & CAPPING BEAM

DESIGNED FOR POTENTIAL FOUNDATION SURCHARGE.

ACCESS RAMP TO ACTIVATION.

SSL 0,000GROUND LEVEL

SSL -3,500BASEMENT

DENOTES TEMPORARY PROPPING.

Status

Drawing No

Date

Drawing Title

Job Title

Checked

RevisionJob No

Scales

Drawn

Status

Drawing No

Date

Drawing Title

Job Title

Checked

RevisionJob No

Scales

Drawn

Copyright © 2019 Michael Hadi Associates Ltd. All rights reserved.

NOTES

1. This drawing is to be read in conjunction with all relevant architects’, engineers’, and specialists’ drawings, employer’s requirements, bills of quantities and specifications.

2. Do not scale off this drawing.3. All dimensions are to be confirmed on site by the contractor.4. Refer to drawing 80 for all general notes.

Michael Hadi Associates Ltd.Consulting Structural Engineers

14-18 Old Street,London, EC1V 9BH.0207 375 [email protected]

As indicated @A1

-

Hero of Switzerland

GM PD

17132 10

Potential Sequence of BasementConstruction

STAGE 2

March 2019

SW9 7LL

Status

Drawing No

Date

Drawing Title

Job Title

Checked

RevisionJob No

Scales

Drawn

Status

Drawing No

Date

Drawing Title

Job Title

Checked

RevisionJob No

Scales

Drawn


NOTES





As indicated @A1

-

Hero of Switzerland

GM PD

17132 10


STAGE 2

March 2019

SW9 7LL

Status

Drawing No

Date

Drawing Title

Job Title

Checked

RevisionJob No

Scales

Drawn

Status

Drawing No

Date

Drawing Title

Job Title

Checked

RevisionJob No

Scales

Drawn


NOTES





As indicated @A1

-

Hero of Switzerland

GM PD

17132 10


STAGE 2

March 2019

SW9 7LL

1 : 200

Stage 2S2

1 : 200

Stage 4S4

1 : 200

Stage 5S5

1 : 200

Stages 6 & 7S6

1 : 100

Stage 8S8

Sequence of Construction

The below method represents a feasible and appropriate preliminary method of construction for the substructure works at the Hero of Switzerland site.

This document is to be read in conjunction with the Demolition & Construction Management Plan dated June 2018 and prepared by K2 Consultancy Ltd. This document covers in greater depth on the structural matters regarding the substructure works.

The final temporary works scheme is to be developed and designed by the chosen contractor.

1. Carefully demolish the superstructure of the existing Public House, top-down and front (Loughborough Road side) to back (Featley Road side). Contractor is to note the basement footprint and take care to avoid high surcharges onto perimeter retaining walls. Suitable material can be crushed and stored for use in the future piling mat.

2. Using suitably battered excavations, carefully demolish the retaining walls to the basement perimeter and then remove the basement slab and grub-out foundations.

3. Partially infill or wholly infill basement excavation using demolition material (or suitably prop to support ground floor construction). Form an appropriate piling mat for the chosen CFA rig, in accordance with BRE470 ‘Working platforms for tracked plant’ . The contractor may decide to infill the basement excavation in sections, if they decide it is more economic to form the piling mat in sections, rather than across the whole site (borrowing material from elsewhere, but retaining an appropriate batter to the perimeter). Or set-down at a slightly lower level the central part of the site (again depending on the chosen piling rig and the slope it can safely travel down to reach the lower level).

4. Install the perimeter contiguous piling. Following immediately behind the piling works form the reinforced concrete perimeter (RC) capping beam.

5. Install sleeves and install the piling for the central part of the site, under the ‘core’ region (contractor may elect to not sleeve and break-down the piles later).

6. Install full-width props (probably hydraulic) onto appropriate bearing spreader blocks set just below the capping beam (so the props do not interfere with the construction of the ground floor slab).

7. Excavate to basement raft formation level. Material is to be removed via a suitable slope near the front of the site.

8. Break-down central piles and construct basement raft slab. Raft slab is to be connected to the all the perimeter contiguous piles.

9. Provide a reinforced concrete lining to the perimeter contiguous piled wall (to suit chosen water-proofing strategy).

10. Construct reinforced concrete walls and columns to underside of ground floor slab.

11. Construct the ground floor slab.

12. Once sufficiently cure, remove the hydraulic propping struts.

13. Construct and complete the superstructure.

14. Excavate and construct the external rainwater attenuation tank and rainwater booster set at the front of the building. Prior to this, this site area can be used for the storage of materials and for welfare facilities (& possibly a tower crane).

Rev Date Made by Amendments

- 22.03.2019 GM Stage 2 Issue






Appendix B – Extracts from Soil Consultant’s site investigation report, dated September 2018 76 pages, including appendices

Head Office Chiltern House, Earl Howe Road Holmer Green, High Wycombe Buckinghamshire HP15 6QT t: 01494 712 494 e: [email protected] w: www.soilconsultants.co.uk

Harwich Office Haven House, Albemarle Street Harwich, Essex CO12 3HL t: 01255 241639 e: [email protected]

Registered in England No 1814762 VAT No 491 8249 15

Cardiff Office 23 Romilly Road Cardiff CF5 1FH t: 02920 403575 e: [email protected]

SITE INVESTIGATION REPORT

PROPOSED REDEVELOPMENT:

HERO OF SWITZERLAND, 142 LOUGHBOROUGH ROAD, LONDON SW9 7LL

Client:

UDN PROPERTIES LTD 65 Delemere Road, Hayes, Middlesex UB4 0NN

Consulting Engineers:

MICHAEL HADI ASSOCIATES LTD

14-18 Old Street, London EC1V 9BH

Report ref: 10281/KOG/OT

Date: 25st September 2018

10281/KOG/OT Site Investigation Report – Hero of Switzerland, 142 Loughborough Road, London SW9 7LL

UDN Properties Ltd Michael Hadi Associates Ltd

25st September 2018 (Rev 0)

SITE INVESTIGATION REPORT

PROPOSED REDEVELOPMENT:

HERO OF SWITZERLAND, 142 LOUGHBOROUGH ROAD, LONDON SW9 7LL

DOCUMENT ISSUE STATUS:

Issue Date Description Author Checked/approved

Rev 0 25/09/18 First issue

Keith Gibbs

BSc, MSc, FGS

Opher Tolkovsky

BSc, MSC, DIC, FGS, CGeol

Alan Watson

BSc [Eng] CEnv CEng MICE

Soil Consultants Ltd (SCL) has prepared this Report for the Client in accordance with the Terms of Appointment under which our services were performed. No other warranty, expressed or implied, is made as to the professional advice included in this Report or any other services provided by us. This Report may not be relied upon by any other party without the prior and express written agreement of SCL.




TABLE OF CONTENTS

1.0 Introduction ..................................................................................................................... 1 2.0 Site description ................................................................................................................. 2 3.0 Phase 1 Preliminary Risk Assessment (Desk Study) ............................................................... 3

3.1 Review of historical information ....................................................................................... 3 3.2 Database information ..................................................................................................... 5 3.3 Other information .......................................................................................................... 7 3.4 Walk-over survey .......................................................................................................... 8 3.5 Potential pollution linkages and Initial Conceptual Site Model .............................................. 8 3.6 Recommendations for intrusive investigation .................................................................. 11

4.0 Exploratory work and laboratory testing ............................................................................. 12 4.1 Rotary auger borehole.................................................................................................. 12 4.2 Trial pits ..................................................................................................................... 12 4.3 Groundwater and gas monitoring ................................................................................... 12 4.4 Geotechnical laboratory testing ..................................................................................... 12 4.5 Chemical and contamination testing ............................................................................... 12

5.0 Ground conditions ........................................................................................................... 13 5.1 Made ground ............................................................................................................... 13 5.2 Taplow Gravel ............................................................................................................. 13 5.3 London Clay Formation ................................................................................................. 13 5.4 Groundwater ............................................................................................................... 14 5.5 Existing foundations ..................................................................................................... 14 5.6 Environmental observations .......................................................................................... 14

6.0 Geotechnical assessment ................................................................................................. 15 6.1 Basement excavation and retaining wall ......................................................................... 15 6.2 Piled foundations ......................................................................................................... 16 6.5 Foundation concrete .................................................................................................... 18

7.0 Basement impact assessment – land stability ..................................................................... 19 7.1 Stage 1 - screening ..................................................................................................... 19 7.2 Stage 2 – scoping ........................................................................................................ 21 7.3 Stage 3 – site investigation ........................................................................................... 22 7.4 Stage 4 – impact assessment ........................................................................................ 22 7.5 Conclusions ................................................................................................................ 23

8.0 Environmental assessment ............................................................................................... 24 8.1 Environmental setting and context ................................................................................. 24 8.2 Contamination sources and testing ................................................................................ 24 8.3 Ground gas/vapour monitoring ...................................................................................... 25 8.4 Disposal of excavated soils ........................................................................................... 26 8.5 Unexploded ordnance risks ........................................................................................... 26 8.6 Refined Conceptual Site Model ...................................................................................... 27

9.0 Additional investigation .................................................................................................... 28

General Information, Limitations and Exception




APPENDIX A

Fieldwork, in-situ testing and monitoring

Foreword Borehole record Standard Penetration Test results SPT hammer calibration certificate Trial pit record Groundwater and gas monitoring results

Laboratory testing

Index property testing Plasticity chart Unconsolidated undrained triaxial test results (QUT) Particle size distribution tests

Ground profiles

Plot of SPT ‘N’ value and undrained cohesion versus depth

Contamination and chemical testing

Foreword General soil suite WAC test results Sulphate/pH suite

Plans, drawings & photographs

Site photographs Proposed development plans and sections Site Plan Location Maps

APPENDIX B

GroundSure historical maps (Ref SCL-5320272) GroundSure EnviroInsight Report (Ref SCL-5320270) GroundSure GeoInsight Report (Ref SCL-5320271)

APPENDIX C

Lambeth Council Contaminated land and historical land use search report

APPENDIX D

GroundSure Preliminary Unexploded Ordnance Risk Report (Ref SCL–532073) RPS UXO Classification Email Report dated 24 September 2018

APPENDIX E

Stephen Buss Environmental Consulting Ltd, Hero of Switzerland, 142 Loughborough Road, Basement Impact Assessment. Report ref. 2018-003-050-001, September 2018

10281/KOG/OT Site Investigation Report – Hero of Switzerland, 142 Loughborough Road, London SW9 7LL Page 1



1.0 INTRODUCTION

The proposed redevelopment of the site will involve demolition of the existing public house and the

construction of a new 14 storey apartment building incorporating a full footprint single level basement. In

connection with the proposed works, Soil Consultants Ltd (SCL) were commissioned by Michael Hadi

Associates Ltd (MHA) on behalf of the Client UDN Properties Ltd, to carry out a site investigation to include

the following elements:

Phase 1 Preliminary Risk Assessment (PRA) including initial Conceptual Site Model (CSM)

Phase 2 intrusive investigation

Provision of advice on foundations, basement excavation, retaining walls and floor slab

Contamination risk assessment and refine Conceptual Site Model (CSM)

Basement Impact Assessment (BIA) – SCL have provided the Land stability element of the BIA.

We commissioned a hydrogeological report from Environmental Consulting Ltd and this is included

as an Appendix to this report.




2.0 SITE DESCRIPTION

The site is located along the south-western side of Loughborough Road and along the north-eastern side

of Featley Road in the London Borough of Lambeth, with its centre at approximate NGR 531690E 175955N,

and with overall dimensions of approximately 15m x 35m. To the south is an adjacent 3- storey apartment

building with small shops at ground level, and associated hardstanding. To the north, between the site

and an 11-storey apartment block, is a grassed open area. Other apartment buildings comprising the

Loughborough Estates, together with areas of landscaped open space are present to the west and east on

the site in the wider surrounding area.

About two thirds of the site is occupied by a single/part 2 storey public house building of traditional

construction (“The Hero of Switzerland”) which was still in use at the time of the investigation. This building

also has a single level part basement or cellar. The external north-eastern part of the site next to

Loughborough Road comprises an asphalt covered beer garden which is partly bounded by a high brick

wall, and a paved area along its western and northern boundaries. Another small open courtyard area,

surfaced with concrete, is present along the south-western side of the main building, with a double gate

opening on to Featley Road and containing a cellar access hatch.

The ground surface of the site is sensibly flat. The Arena Property Services Ltd (APS Ltd) topographic plan

and existing ground and basement floor plans, (Ref 18019-13-T and 18019-13-B-G and 18019 B- B

respectively) indicate ground levels to range from about +11mOD along the south-western side to about

+10.7mOD along the north-eastern side of the site. The floor of the public house is raised by about 0.3m

above external ground level and the basement is about 2.5m deep; this basement level is approximately

+9.0m OD. The survey plans are included in Appendix A.

A Lime tree (17m tall) and a Cherry tree (9m tall) are presently growing on land to the north of the site.

Other smaller trees are present to the east and south.

The current site features are shown on the Site Plan and on photographs taken at the time of our fieldwork

all of which are included in Appendix A (and on the front cover of this report).




3.0 PHASE 1 PRELIMINARY RISK ASSESSMENT (DESK STUDY)

This assessment is generally based upon current UK guidance, primarily the combined DEFRA/EA

publication CLR 11 (Model Procedures for the Management of Land Contamination, 2004). The scope of

the assessment is as follows:

A review of historical and current land–use and potential contaminated land risks

Development of an outline conceptual model, identifying potential sources, pathways and receptors

Development of a strategy for Phase 2 intrusive investigation

3.1 Review of historical information

The following summary of the history of the site and surrounding area has been compiled from a series of

historical maps obtained from a commercially available database; these are included in Appendix B.

Historical development of site and surrounding area

Map date The site Significant development / features in

surrounding area

1870/1938 The site is mainly occupied by

a pair of semi-detached

residential properties and

associated gardens, on

Loughborough Road and just

N of Barrington Road which

trends to the SW.

The residential plots are

orientated in an approximate

E-W direction as opposed to

the current SW to NE

orientation.

The surrounding areas are developed with semi-

detached and terraced residential houses with

large rear gardens.

The earliest large-scale map of 1873-1874 shows a

public house is present about 25m N along

Loughborough Road. A Pump is shown about 40m

N along Loughborough Road and a standpipe about

55m S along Barrington Road.

E-W and N-S trending railway lines are present to

the E and S of the site. These lines intersect about

300m SE and with the nearest spur line (and

Loughborough Road station, later Loughborough

Junction) about 200m SE.

From 1894, nurseries are shown about 30m NW

and next to the public house previously noted

along Loughborough Road.

The 1916 edition shows the Head Quarters of the

6th London Brigade RFA Territorials to be present

some 90m E

The 1920 edition shows another nursey along the

E side of Loughborough Road about 300m N.

The maps in this series show a gradual increase in

the density of residential development.




Historical development of site and surrounding area

Map date The site Significant development / features in

surrounding area

1948 The site is shown as clear of

any development with all

traces of former houses now

absent. This absence may be

indicative of WW2 bomb

damage.

The immediate area around the junction of

Barrington Road and Loughborough Road is shown

as devoid of any structures which we attribute to

demolition following likely bomb damage in WW2

(see later discussion).

1950 - 1954 The site comprises gardens of

new houses constructed along

Barrington Road Gardens.

A Ruin (previously noted former public house) is

shown 20m to 25m N which is surrounded by

undeveloped open space. Similar open space is

shown to the S of Barrington Road Gardens and to

the SW of Angell Road.

New housing layouts are shown to the E and S.

Electricity substation is shown 170m E.

1958-1968 The site is again shown as

clear of any development with

the former houses along

Barrington Road Close now

absent.

Featley Road has been constructed and a block of

terraced houses is shown immediately to the S of

the site.

A new high-rise apartment building (Leicester

House) is shown about 10m N of the site. Other

similar tower blocks are shown to the N, W and S.

New terraced houses have been built along the NE

side of Loughborough Road.

Works identified 150m E of the site.

1973 to

present

The current site outline is

now present, with the

majority of the site occupied

by a public house building

and associated external

areas.

The surrounding areas have remained largely

unchanged and remain predominantly residential

in character.

An electricity substation is shown 30m S of the site

adjacent to a Child Health Centre (building

redeveloped in early 2000’s and substation not

currently observed from street).

Council Yard identified 100m E of the site.




3.2 Database information

The database report includes information of local activities encompassing a range of subjects related to

land use, pollution, and geological/hydrological conditions. Our assessment of contaminative uses and

other environmental issues relevant to the site and its surroundings is provided below. The full database

report is included as Appendix B and this should be read and understood fully in conjunction with this

summary.

Groundsure EnviroInsight Report (Ref SCL-5320270)

Historical Industrial Sites

Potentially contaminated uses (within 250m): Various nurseries are identified in the local area with

the nearest record for the 1894 map on-site. Our map review (see above) has, however, noted the

site to straddle two residential properties at this time. In this review the nearest nurseries were

identified about 20m N. The remaining entries within 250m relate to railway buildings/station.

Historical tank database (within 250m): Unspecified tanks noted 98m NE, 137m N, 178m NE and

196m S.

Historical energy features database (within 250m): Electricity substations noted 28m S, 84m N,

116m SW, 117m NW, 170m NW, 173m E, and 180m NW.

Historical petrol and fuel site database: No data present.

Historical garage and motor vehicle repair database: Nearest 388m W.

Potentially infilled land (within 250m): Nearest 422m S for unspecified heap.

Environmental Permits, Incidents and Registers

Records of Part A(2) and Part B Activities: 225m SE and 405m NW for dry cleaners, 409m SE

Waste oil burning, 429m SE for Petrol service station – Historical permit, 445 SE Herne Hill petrol

station – Current permit. No enforcements for any of these locations.

Records of Category 3 or 4 Radioactive Substances Licences: None.

Records of Licensed Discharge Consents: None within 500m.

Landfill and other Waste Sites

Waste treatment, transfer/disposal sites with 500m: 80m E for scrap yard – historical. 351m SE

for recycling facility – historical.

Records of Environment Agency waste sites within 500m: Nearest 180m E and 244m NE - vehicle

depollution facility, 274m SE for Tenmead Ltd for HCI waste TS and treatment, 461m SE London

Borough of Lambeth for a clinical waste transfer station.




Current Land Use

Potentially contaminative uses: 26m S, 94m N, 116m SW, 119m NW, 169m NW, 182m E -

electricity substations. Others notable entries include scrap metal merchants 175m NE, 192m E

and 241m NE, unspecified works or factories 180m E, vehicle repair 221m-234m SE and 237m-

248m NE, Loughborough Junction Rail Station 245m SE. A number of entries probably refer to

office premises and would not therefore be contaminative

Petrol and Fuel sites: 431m SE for Herne Hill Service Station – open.

Hydrogeology and Hydrology

Aquifer within superficial deposits: ‘Secondary A’ (Taplow Gravel).

Aquifer within bedrock deposits: ‘Unproductive’ (London Clay).

Groundwater Abstraction: None within 500m of site, the nearest being 646m E, Thames

groundwater borehole.

Surface Water Features: None identified within 250m.

Potable Water Abstraction: None within 1000m of the site, the nearest being 1976m SW.

Source Protection Zones: The site is not within any source protection zones.

River Quality: No data.

Detailed River Network: No data.

Flooding

No Zone 2 or 3 floodplains or flood defences within 250m of site.

Risk of flooding: Very low.

Groundwater Flooding Susceptibility Areas: Clearwater flooding of superficial deposits with potential

at surface (moderate confidence).

Designated Environmentally Sensitive Areas: None




Groundsure Geo Insight Report (Ref SCL-5320271)

Geology

Artificial /Made Ground: No records.

Superficial Deposits/Drift Geology: Taplow Gravel (high to very high permeability) on site.

Bedrock/Solid Geology: London Clay (very low to low permeability).

Radon: The property is not in a Radon Affected Area (<1% of properties are above action level) -

no protective measures required.

Historical Surface/Underground Workings: No records.

Mining, Extraction & Natural Cavities: Single record for chalk mining 903m NE (considered not

relevant to site). No other entries.

Natural Ground Subsidence: Very low to negligible risks for all categories where identified.

Borehole Records Map: 16no within 250m of site.

Estimated Soil Background Chemistry: No data

Railways and Tunnels: Historical tunnels 188m E and 224m E. Nearest Active railways 191m E.

3.3 Other information

Local Authority search

The London Borough of Lambeth hold a database of historical land uses which is not included in the

Groundsure database. A report was commissioned from Lambeth Council and this is incorporated as

Appendix C.

Their report concludes that their database search for the site and the surrounding area has found no records

of contamination. They also have no enforcement concerns relating to Part IIA of the Environmental

Protection Act 1990 and therefore do not intend to carry out any investigation under this legislation.

The report goes on to list various current and historical records for activities around the site. These are

broadly consistent with those outlined in the Groundsure review above.

Groundsure Unexploded Ordnance risk assessment reports

The preliminary Groundsure UXO threat assessment report (Ref SCL-5320271] noted a High Risk

classification for WWS2 related unexploded ordnance at the site. A subsequent review by RPS confirmed

a lower level ALARP (as low as reasonably practicable) classification with an allowance for a UXO clearance

engineer to be on call and to attend site if any suspicious objects were discovered during intrusive works.

Both the Groundsure and RPS reports are included in Appendix D.




3.4 Walk-over survey

A site walk-over survey was undertaken on 23rd August 2018. A description of the general features of the

site and the topography is provided in Section 2.0 above. From inspection of visible and accessible areas,

a summary of specific features relevant to the land quality assessment is as follows:

Feature

Commentary

Electricity substations and

transformers

None identified in proximity to site although the desk study review has noted a

substation 28m S

Fuel storage tanks None on site

Fuel interceptors None on site

General chemical

storage/waste

None noted in external areas

Storage contained in basement/cellar consistent with existing site usage as public

house

Invasive species None noted

Evidence of gas protection None noted

Surface water

contamination

No surface water present

Waste storage Site is reasonably tidy and in use as Public house

ACMs None noted but may be present in rooting/flooring and as lagging around pipes in

basement

Anecdotal information During fieldwork the pub landlord informed that the cellar has been known to

slightly flood in the past, though this flooding did not wholly coincide with

increased rainfall.

3.5 Potential pollution linkages and Initial Conceptual Site Model

The information in the preceding sections has been used to undertake the Preliminary Risk Assessment and

to compile the Initial Site Conceptual Model below. The assessment follows as risk-based approach, with

the potential risks determined qualitatively using the ‘source-pathway-receptor’ linkage concept; a risk of

harm may only exist where a plausible linkage is present. The assessment has been formulated based on

the following table:

Consequences

Severe Medium Mild Minor

Pro

bab

ilit

y

High likelihood Very high risk

High risk Moderate risk Moderate/low risk

Likely High risk

Moderate risk Moderate/low risk Low risk

Low likelihood Moderate risk

Moderate/low risk Low risk Very low risk

Unlikely Moderate/low risk

Low risk Very low risk Very low risk




Definitions of the risks are summarised as follows:

Very high: high probability that severe harm could occur, or there is evidence that it is currently

occurring. If realised, the risk could result in substantial liability. Urgent investigation/remediation

High: harm is likely to occur, realisation is likely to present substantial liability. Urgent

investigation required. Remedial works may be required in short-term, will be in long-term

Moderate: possible that harm could arise, but unlikely to be severe. Investigation normally

required to clarify risk and liability. Remedial works may be necessary in long-term

Low: possible that harm could occur, but this would at worst be mild

Very low: low possibility of harm, unlikely to be severe

The assessment has been carried out by identifying and evaluating the potential sources of contamination,

the potential receptors and the plausible pathways for contamination migration are summarised as follows:

Potential sources of contamination

Potential Source

Element/Compound potential

On site

Building built pre-2000 Asbestos

Made ground

Commercial public house usage

Hydrocarbons (TPH, PAH)

Heavy metals/semi metals

Inorganic or organic chemicals

Ground gas and VOCs

Off site

No significant potential sources identified

apart from historical record of nearby

substation

No significant risk of cross contamination

identified apart from possible relict PCB

contamination

Potential receptors

In the context of the proposed development, the following potential receptors have been identified:

Human health: inhabitants/users of building, construction workers, adjacent site users

Controlled waters: Secondary aquifer of the Taplow Gravel underlain by Unproductive London Clay.

The site is not located within a source protection zone and there are no relevant surface or

groundwater within a relevant distance of the site. The site is assessed as being of Low to

medium environmental sensitivity

Building fabric and services: buried foundations, basement wall, potable water pipes




Plausible pathways

Ingestion of soil, dust or water

Inhalation of dust, gas or vapours

Direct physical contact with contaminated soil/water

Vertical and lateral migration of contamination including leaching

Chemical attack of building infrastructure, including water supply pipes

Migration of ground gas/vapour through permeable soils or open pathways

The Initial Conceptual Site Model and an estimate of the risk associated with each potential linkage is shown

in the following table:

Source Pathway Receptor Assessed risk and commentary/justification

On-site:

contaminated soil

Ingestion, contact,

inhalation

End user,

construction

workers and

infrastructure

Low risk: no significant historical potential sources

identified on site and currently, the main potential source

is the anticipated made ground layer. Proposed basement

will remove bulk of made ground with hardstanding

proposed over remaining new beer garden so potential for

direct contact would be eliminated

Leaching from

contaminated soils

and migration in

groundwater

Aquifer and

surface water

Low risk: basement will remove bulk of made ground and

proposed scheme envisages 100% hard cover eliminating

any water infiltration. High permeability secondary

aquifer present above relatively impermeable London Clay

which would provide barrier above any deeper chalk

aquifer

Off-site:

contaminated soil

Lateral migration of

contaminants to site

in groundwater

End user

Low risk: main identified off-site sources are historical

commercial/industrial activities in the general area (none

identified in immediate vicinity of the site); however,

these were largely redeveloped into residential use

following WW2. Historical record of substation nearby.

On-site and off-

site: ground gas

and vapours

Lateral and vertical

migration of

gas/vapour

End-user and

buildings

Low risk: no significant potential gas/vapour sources

identified. The site is not in a radon affected area

The overall risk rating for the site is assessed as being Low to moderate.




3.6 Recommendations for intrusive investigation

The Initial Conceptual Site Model identified potential pollution linkages resulting in the overall assessed risk

rating of moderate. The following programme of intrusive investigation is recommended:

Suitable intrusive investigation to confirm the ground sequence, allow soil sampling and the

installation of monitoring pipes

No specific contamination sources were identified by the PRA so the investigation should provide

general suite of analysis with possible targeted PCB analysis in area closest to the location of the

substation noted in desk study review to the south of the site

Soil samples should be recovered where relevant and be analysed for a range of general

contaminants to include petroleum hydrocarbons, PAHs and asbestos screening

Groundwater and gas monitoring

The Initial Conceptual Site Model should then be revised to include complete pollution linkages and outline

mitigation/remedial measures should be identified, together with any requirements for additional

investigation.




4.0 EXPLORATORY WORK AND LABORATORY TESTING

The scope of the initial phase of ground investigation was devised by the structural engineer, and it was

carried out on 23rd August 2018. At this time only a limited area was available for investigation due to the

continued commercial operation of the public house; a further deep borehole is proposed at a later stage

to provide full pile design information. The investigation comprised the following elements.

4.1 Rotary auger borehole

A single borehole was carried out in the beer garden area using a tracked auger equipment under the

supervision of an experienced engineer. In-situ testing was carried out at appropriate intervals and

representative samples, both disturbed and relatively undisturbed U100s were taken for geotechnical and

environmental testing. PID headspace testing was also carried out. The borehole was taken to 12m depth

and a monitoring pipe was installed in the borehole to 6m depth upon completion. The hammer Energy

Ratio (Er) for the equipment used was 78%; the relevant test certificate is appended.

4.2 Trial pits

Two trial pits were undertaken using hand tools. TP1 which was positioned in the existing basement was

terminated when groundwater inflow occurred at shallow depth. TP2 was excavated along the

external/northern side of the pubic house.

4.3 Groundwater and gas monitoring

Water and gas monitoring was carried out on one occasion following completion of the site works on 4th

September 2018.

4.4 Geotechnical laboratory testing

The following geotechnical laboratory testing was completed:

Index properties tests (Atterberg Limits)

Particle size distribution tests

Unconsolidated, undrained triaxial tests

4.5 Chemical and contamination testing

Selected soil samples were delivered to a specialist laboratory (DETS Ltd) and the following testing was

carried out:

General soil suite - 3no samples

Asbestos screening - 3no samples

Waste Acceptance Criteria (WAC) - 1no sample

Soluble sulphate/sulphur/pH analyses - 8no samples

The engineering borehole and trial pit logs and the laboratory testing results are included in Appendix A




5.0 GROUND CONDITIONS

Published BGS information (1:50,000 and 1:10,000 scale maps) indicates that the site is underlain by the

Taplow Gravel which rests upon the London Clay Formation. There are no deep BGS registered boreholes

nearby, however, our research indicates that the interface of the London Clay and the underlying Lambeth

Group is likely to be in excess of 25m depth. The sequence confirmed by our investigation is summarised

as follows with detailed strata descriptions presented on the borehole record in Appendix A.

5.1 Made ground

At BH1, below a surface layer of asphalt and in TP2 below a surface layer of topsoil, made ground extended

to depths of 0.90m and 1.40m respectively, and comprised a mottled grey and brown gravel with a sandy

and silty matrix. The gravel comprised a mixture of brick and concrete rubble and occasional slate

fragments.

5.2 Taplow Gravel

The natural Taplow Gravel was met beneath the made ground and extended to a depth of 5.90m below

ground level (bgl), about +5.2mOD. Initially, this deposit occurs as a firm orange brown slightly gravelly

sandy clayey silt extending to about 1.85m depth. The result of an SPT test within this layer indicates a

medium strength classification and Atterberg limits testing indicates this cohesive layer to correspond to a

low plasticity silt (BS) with a PI value of 4%. The modified PI value [to take account of the proportion of

fines present} indicates this soil to be effectively non-shrinkable according to the NHBC guidance.

Below the initial clayey layer, a sequence of orange brown and brown variously clayey, silty and sandy

gravel or gravelly sand was met. The particle size analyses confirm between 23% and 51% gravel content,

23% to 36% sand content, 7% and 24% silt content and 11% and 17% clay content.

The results SPT testing indicate the sand and gravel to initially be in a medium state of compaction to about

2.50m (SPT ‘N’ value of 22), below which the soils occur in a very dense state (‘N’ values>50).

5.3 London Clay Formation

The London Clay was met at a depth of 5.90m with a thin brown weathered upper layer to 6.20m depth,

below which this grey fissured clay was present. Occasional silt partings were noted within the clay.

Laboratory triaxial testing and SPTs indicate the London Clay to be of a high strength - the measured

strength profile in included in Appendix A. This formation extended to the base of the borehole at 12m

depth (-0.90mOD).

Atterberg limits tests indicate the London Clay to correspond to a very high plasticity (BS) clay with PI

values ranging between 49% and 56% which corresponds to a high volume change potential in accordance

with the NHBC guidance.




5.4 Groundwater

In BH1, groundwater was encountered during drilling within the Taplow Gravel at about 4.2m depth, and

a rest level of 3.95m was measured during subsequent monitoring of the standpipe. A water inflow met

during the shallow excavation from basement level of TP1, we attribute to the local occurrence of trapped

water directly below the slab.

Groundwater levels can of course vary seasonally and with prevailing weather conditions.

5.5 Existing foundations

A detailed record of the trial pit is included in Appendix A. A summary of the findings of the internal trial

pits is as follows:

TP ref Location Foundation details

TP1 Basement of existing public house Slab estimated at 300mm to 400mm thick by pilot drilling. Water seepage at 0.05m. Pit not completed

TP 2 Wall along northern side of public house Masonry wall extends to 0.75m depth. Concrete footing underside possibly at 1.40m in dense

gravel (unable to fully confirm depth due to services)

5.6 Environmental observations

No obvious olfactory or visual signs of soil or groundwater contamination were encountered in the

boreholes. PID headspace testing (for VOC concentrations) has been undertaken and no elevated levels

were noted.




6.0 GEOTECHNICAL ASSESSMENT

The proposed works at this site include demolition of the existing structures and the construction of a new

14 storey tower building covering the central and south-western part of the site. The building will have a

full footprint single level basement. The Gensler proposed building section drawing (Ref 08.7369.000.

A1.300 dated 10 October 2016) indicates a basement FFL of about 3.5m below ground level to

accommodate plant equipment, and the ground floor will be partly occupied by a new pubic

house/restaurant and substation.

Details of the anticipated column loads were available at the time of compiling this report but we understand

that the total weight of the new building is likely to be about 75MN with an equivalent uniformly distributed pressure of around 230KN/m2. The Engineer’s current foundation options include either a raft foundation

with bored piles under the stabilising central core, or a fully piled solution. The basement retaining walls

may either be formed by a piled wall or alternatively by reinforced concrete walls connected to the raft

foundation.

Further exploratory work to greater depths is currently envisaged to provide full appropriate design

parameters, however, some preliminary conclusions can be drawn from the initial investigation undertaken.

Our investigation has revealed that made ground is present to about 1.5m depth overlying the competent

natural Taplow Gravel which rests upon the London Clay Formation at about 6m depth. Groundwater is

present close to the proposed basement formation level, which may rise above this level during wetter

periods. Both the combined raft/piled option and the fully piled option could be considered to support the

new structure. From the history of the site, buried obstructions may be present and thus obstructions in

the ground should also be anticipated.

6.1 Basement excavation and retaining wall

Below any surface layers of made ground the excavation for the proposed basement is expected to be

wholly within the Taplow Gravel. Groundwater is present in the gravel and based on the monitoring to

date is likely to occur at or immediately below the proposed basement formation (after allowing for the

floor slab construction thickness). Based on this water level either of the proposed options (ie, a reinforced

concrete retaining wall or contiguous piled wall) could be appropriate. The level of the groundwater will

clearly be critical and higher groundwater levels would be anticipated during the winter months. Before

the design is finalised, further investigation and groundwater monitoring must be undertaken to confirm

the worst case water levels, and if these are above the proposed excavation level, a water tight system

such as a secant piled wall design could be required. Whichever method is adopted a robust arrangement

of temporary internal bracings/props, including support elements near the top of the basement wall, will

be required to maintain wall stability and assist in controlling ground movements during construction.

Careful selection of the appropriate design parameters will be needed, incorporating allowances for factors

such as the presence of groundwater and the possibility of soil softening. The following table of coefficients

may be used for the preliminary design of the basement retaining wall:




Stratum Bulk density

(Mg/m3)

Effective cohesion, c’

(kN/m2)

Effective friction angle, I’

(degrees)

Made ground

1.80 0 22

Taplow Gravel

2.00 0 35

London Clay:

<5m below basement level

>5m below basement level

2.00

2.00

0

5

21

21

Eurocode 7 stipulates that partial material factors must be applied to the best estimates of geotechnical

soil properties during the design stage. The design engineer must ensure that the correct comparisons are

made between Design Actions and Design Resistances after the application of appropriate partial factors.

The determination of appropriate earth pressure coefficients and the pattern of earth pressure distribution

should be carried out by the geotechnical designer; these will depend upon the type/geometry of the wall

and the overall design approach. If a piled perimeter wall is adopted then these piles may of course also

be used to provide vertical load capacity subject to the necessary allowance being made for interaction

effects. We recommend that a specialist contractor is consulted to confirm the most appropriate type of

wall and to provide the final wall design.

6.2 Piled foundations

The final design of piled foundations will need to be informed with data from greater depths than that

currently achieved. For the ground conditions encountered to date, with groundwater being present within

the Taplow Gravel and likely present as minor inflows within the deeper lying London Clay/Lambeth Group,

we consider that CFA piles will present the optimum type.

If piles need to be extended into the Lambeth Group strata then some modification of the pile parameters

or downgrading of the pile capacities may be warranted to mitigate the possible risk of clay softening,

although this should be minimal with well-installed CFA piles. In this situation consideration could be given

to designing the piles to achieve the required capacity wholly within the more uniform London Clay.

A piling specialist must be consulted at an early stage to advise on the most appropriate pile type and to

ultimately provide the final pile design. This should address issues such as the potential clay softening and

the relative performance of the probable clay and sand layers within the Lambeth Group. If pile testing is

undertaken it will be possible to apply lower partial factors, resulting in increased pile resistances, however,

this may not be economical given the relatively small scale of this project.




6.3 Basement slab [non-raft] and heave

If a fully piled foundation is to be adopted to support he structural loads, then a conventional basement

floor slab will be constructed. The basement excavation will involve the removal of up to 4m [allowing for

basement slab thickness) of soil below the proposed building footprint, resulting in unloading of about

80kPa. This stress reduction will theoretically result in an element of heave in the London Clay.

The potential long-term effect of this heave in the London Clay as it recovers should be considered during

slab design. The slab could be designed as a fully suspended structure, supported on the main foundations,

and incorporating an effective void beneath to accommodate future heave movement. Assuming a worst-

case situation of the maximum reduction in overburden (up to say 4m) over the maximum basement area

(14m x 20m), preliminary analysis indicates that a total unrestrained heave of between about 20mm to

30mm could occur as a result of the unloading. Approximately 50% of this heave movement is likely to

occur during a typical construction programme, leaving a maximum possible post-construction heave of

10mm to 15mm to be accommodated.

In reality the amount of heave will also be affected by other factors such as the fact that a basement

already exists to about 2.5m depth over part of the site, therefore some unloading of the London Clay

would already have occurred in this area. Also the length of the construction programme and the

restraining effect of the basement slab stiffness and not least the presence of the remaining Taplow Gravel

below the basement slab can all have significant impacts.

The alternative to a fully suspended voided slab would be to use a ground bearing slab which is designed

to withstand potential heave forces/movements. If it is (reasonably) assumed that the relationship

between heave movement and pressure is linear, the maximum heave pressure for an infinitely stiff slab

could therefore be about 35kPa for the fully constrained condition. However, this will not occur in reality

and the heave pressure beneath a more flexible slab will clearly be less (due stress dissipation as the slab

deflects); we anticipate that an ‘average’ stiffness slab would experience heave pressures of the order of

15kPa with heave movements of <10mm.

It will be necessary to consider uplift of the slab due to potential hydrostatic pressures and in this respect

the guidelines incorporated in BS8102:2009 should be followed. The slab design will need to take account

of potential seasonal fluctuations and/or accidental and flood conditions. We recommend that a design

water level at 1m depth below current ground level is adopted for preliminary purposes and this would

result in a hydrostatic uplift pressure of about 25kPa on the basement slab; this design water level may

need to be agreed with the local building control.

6.4 Basement raft foundation

If the layout and configuration of the new loads permit, a reinforced concrete basement raft could be

considered (subject to acceptable stresses/settlements). This would be a significantly more robust

structure than the basement slab and would be designed to effectively distribute the loads over the whole

new basement footprint.




Initial calculations indicate at the design pressure the raft foundation would experience a total settlement

of up between 100mm and 150mm. This settlement is likely to be excessive and it is considered that a

hybrid piled-raft foundation will be required to control settlements. The number and configuration of the

piles would be need to be determined following further investigation and finalisation of the loads. A detailed

Ground Movement Analysis (GMA) will probably be required to address potential settlements in detail,

particularly along the site boundaries and to determine soil/structure interactions for the piled raft structural

design.

6.5 Foundation concrete

Low concentrations of water soluble sulphates (2:1 water/soil extract) were measured in selected soil

samples, with slightly alkaline pH values. The results fall into Site Design Class DS-1 of Table C2 given in

BRE Special Digest 1 (2005). We assess the site as having ‘mobile’ groundwater and this would result in

an ACEC Site Class of AC-1.

Consideration should also be given to the potential oxidation of pyritic soils. Following the procedure

recommended in the BRE digest, the amount of oxidisable sulphides is seen to be >0.3% in two of the

samples of London Clay, suggesting that pyrite is probably present. The characteristic value of Total

Potential Sulphate is 1.05%, which equates to Class DS-3 with a resultant classification of ACEC AC-3. If

it is deemed unlikely that the piles and basement raft/slab will be exposed to disturbed ground which might

be vulnerable to oxidation, this more onerous classification may not be required; this must be determined

by the pile/raft designer who should provide the final classification.




7.0 BASEMENT IMPACT ASSESSMENT – LAND STABILITY

This section of the report assesses the potential impact relating to the proposed subterranean development

in terms of ‘Land Stability’ as required by Lambeth Council’s ‘Basement Development SPD’, October 2017.

This guidance requires the impacts of the proposed development to be adequately considered using

appropriate professional expertise, and that the structural stability of neighbouring buildings and

infrastructure will not be put at risk.

The hydrological/hydrogeological aspects of the basement impact assessment have been assessed

separately by a specialist hydrogeologist (Stephen Buss – Environmental Consulting Ltd), which is attached

as Appendix E.

7.1 Stage 1 - screening

The proposed development involves the replacement of the existing public house with a multi-storey

apartment building. The new building will have single level basement extended beneath the whole footprint

which will require some deepening below the existing part basement. The ground investigation reported

above provides site-specific information on the ground and groundwater conditions at this site to allow an

informed assessment to be made.

The following section addresses the key geological/land stability issues upon which the construction method

statement (usually reported by the project Structural Engineer) needs to be based.

The purpose of the screening stage is to determine whether a full Basement Impact Assessment is required.

In the absence of specific questions raised in the Lambeth Council document, we have based our

assessment on Camden Council’s comprehensive CPG4 which provides flowcharts for this purpose,

identifying a series of questions. An answer of ‘Yes’ or ‘Unknown’ will require progression to Stage 2 of the

CPG4 categories. Answers of ‘No’ indicate that no further investigation is generally required - these answers

require written justification. The purpose of this section is to present the screening stage for the Land

Stability discipline as follow;

Impact question Answer Justification Reference

1) Does the existing site include

slopes, natural or man-made

greater than 7° (approximately 1

in 8)?

No x The site does not contain significantly sloping ground and is sensibly flat and level

x Observations during site visit and topographic plans

2) Will the proposed re-profiling of

landscaping at site change slopes

at the property boundary to more

than 7°?

No x No re-profiling or landscaping proposed

x Proposed development plans/architectural drawings

x Discussions with engineer

3) Does the development

neighbour land, including railway

cuttings and the like, with a slope

greater than 7°?

No x No significant slopes present in neighbouring land

x OS mapping and observations during site visit





4) Is the site within a wider

hillside setting in which the

general slope is greater than 7°?

No x Surrounding areas have slopes of <7° x OS mapping indicates approximate

slope angles of 1v:50h in the wider area

x OS mapping

5) Is the London Clay the

shallowest stratum at the site?

No x Made ground and Taplow Gravel are present above the London Clay (see SCL report above)

x BGS mapping x This site investigation report

6) Will any trees be felled as part

of the proposed development

and/or any works proposed within

any tree protection zones where

trees are to be retained?

No x Trees are not present on the site

x Observations during site visit x RPS tree survey report (Ref JSL

3129- 770, dated 20th August 2018)

7) Is there a history of seasonal

shrinkage/swelling subsidence to

the local area, and or evidence of

such effects at the site?

Not as far

as known

x Shrinkable clay soils are not present at shallow depth and we are not aware of any issues with seasonal shrinkage/swelling subsidence in the local area

x This site investigation report x It is recommended that

insurance claim data are checked in this regard

8) Is the site within 100m of a

watercourse or a potential spring

line?

No x No surface water features/spring lines identified within 100m of site in the desk study information Nearest watercourse shown on Lost Rivers of London map is River Effra, 500m west.

x Groundsure desk study information

x Lost Rivers of London by Nicholas Barton

9) Is the site within an area of

previously worked ground?

No x None identified


x BGS mapping

10) Is the site within an aquifer?

If so will the proposed basement

extend beneath the water table

such that dewatering may be

required during construction?

Yes

x The site is underlain by bedrock classified as ‘Unproductive’ and a ‘Secondary A’ superficial aquifer There is a possibility that dewatering may be required during construction and this should be checked by future additional ground investigation and groundwater monitoring.


x This site investigation report

11) Is the site within 5m of a

highway or pedestrian right of

way?

Yes x The site borders Loughborough Road to the north-east and Featley Road to the south-west (the main proposed basement work only borders Featley Road)

x Site plans and proposed scheme drawings

12) Will the proposed basement

significantly increase the

differential depth of foundations

relative to neighbouring

properties?

Unknown x The proposed basement will require foundations at about 3.5m depth. The depth of foundations to neighbouring properties is unknown. There are however no neighbouring structures directly abutting the site

x Site observations





13) Is the site over (or within) the

exclusion zone of any tunnels, e.g.

railway lines?

No x Nearest known active railway line is located 190m east of the site

x TfL Property Asset Register (Public Access) indicates the nearest exclusion zone is located along the Victoria Underground Line at Brixton Station some 600m SW of site

x OS mapping x TfL Property Asset Register

(Public Access) website

Responses of note are as follows:

Question 7 (Shrink/swell) is answered ‘Not as far as known’.

We are not aware of any insurance claims at the neighbouring properties but the shrink/swell risk is

considered very low for this site based on the lack of current observed significant vegetation and the

presence of non-shrinkable soils to 5.9m depth on site. The database of insurance claims in this regard

should be consulted to verify this assumption

Question 10 is answered ‘Yes’. A groundwater inflow as also noted during the exaction of TP1 at about

2.14m depth on 23rd August 2018, which is within the depth of the proposed basement excavation but

may be indicative of trapped water below the existing basement slab. We consider a more reliable

indicator of the groundwater level would be that measured in BH1 at a depth of 3.95m, on 4th

September 2018 which would be just at or just below the likely basement formation. In any event

the potential for seasonal fluctuations in groundwater conditions indicates that further investigation

and monitoring is recommended.

Question 11 (is the site within 5m of a highway or pedestrian right of way?) is answered ‘Yes’: this is

considered further in the following stages.

Question 12 (Will the proposed basement significantly increase the differential depth of foundations

relative to neighbouring properties?) is answered ‘Unknown’: There are however no neighbouring

buildings immediately adjacent to the site and the risk of the proposed construction significantly

affecting neighbouring buildings is considered to be low.

7.2 Stage 2 – scoping

The purpose of the Scoping Stage is to assess the potential impacts of the proposed scheme that Stage 1

has indicated require further consideration.

As identified above, the slopes within influential distance of the site are all shallow (<7°) and no significant

impact is anticipated on sloping ground in terms of land stability.

Groundwater conditions may be subject to seasonal variations and may be a significant construction issue

(Question 10) as seepages were noted at existing basement level in the investigation and the main water

level within the Taplow Gravel may be at or very close to the basement excavation formation. Additional

monitoring will be required to verify seasonal variation. If water levels rise above basement level then the

construction methodology will have to be re-assessed. Any groundwater control should utilise screened




pumps to prevent loss of fines. The hydrology/hydrogeology aspects are further discussed by Stephen

Buss Environmental Consulting Ltd (see Appendix E and Section 7.4 below).

With regard to the proximity of a highway or pedestrian right of way (Question 11), whilst Loughborough

Road is located north-east of the site, the basement excavation will be set back from this thoroughfare by

the retention of a ground level hardstanding area. To the south-west the basement would be immediately

adjacent to Featley Road. A pedestrian area and car park are also present along the south-eastern side.

A carefully-designed and constructed retaining structure will ensure that no adverse effects occur due to

the construction; the movement expected from a properly constructed and supported wall should be very

small.

There are no party walls to the proposed basement however an assessment of the effect on the differential

depth of foundations for adjacent properties within the zone of influence of the basement should be

undertaken (Question 12).

7.3 Stage 3 – site investigation

A preliminary ground investigation has been conducted by SCL at the site in order to provide information

on ground/groundwater conditions and so allow the Stage 4 (Impact Assessment) to be conducted.

7.4 Stage 4 – impact assessment

The purpose of Stage 4 is to assess the potential impacts of the proposed scheme that the preceding stages

have indicated require further consideration. These are summarised below

Potentially impacting

attribute

Assessed Impact Mitigation measures required and further notes

Ground movement/

stability

Exposure in excavation

and support for new foundations

Both made ground and natural Taplow Gravel are expected

to be present within the excavation depth and the latter stratum should form the bearing soil for any new foundations. Settlements/ground movements should be

assessed based on the results from the ground investigation already conducted and any future investigations




Potentially impacting

attribute

Assessed Impact Mitigation measures required and further notes

Groundwater

Question 10

Unlikely impact subject

to further monitoring

The current investigation indicates that groundwater may

be subject to seasonal variation and there may be periods

when groundwater is within the proposed basement

excavation depth.

The hydrology BIA by SBEC indicates that winter levels may

peak about 0.3m above summer levels, however, should

future monitoring indicate a significant rise in groundwater

level, above the proposed basement excavation, then the

construction methodology will have to be re-assessed and a

water-tight embedded piled solution (such as a secant wall)

will likely have to be considered. In this scenario, pumping

will be required as part of the construction process,

following installation of the retaining wall

Ground Stability

Questions 11 & 12

Likely impact A retaining wall will be required to form the new basement.

This work must be undertaken following careful design and

construction methods that provide both short- and long-

term support to neighbouring land and minimise any ground

movements

Initial and final condition surveys should be undertaken for the neighbouring buildings; monitoring to be undertaken during construction and a plan of action to be instigated in

response to any departures from appropriately set limits

7.5 Conclusions

From the available information, we consider that the risk to ground stability from this development should

be relatively low. Most ground movement problems occur due to construction issues thus the works must

be undertaken by reputable experienced specialists and the temporary and permanent works are

adequately designed, with due consideration to the geology and hydrogeology of the site and surrounding

areas. Further groundwater monitoring will need to be undertaken prior to construction to verify levels,

particularly during wet periods, as this may have a significant impact on the construction methodology.

We conclude that for the proposed basement construction, it should be possible to design the construction

methods to ensure that ground movements do not adversely affect either adjacent properties or

infrastructure. A ground movement analysis should be undertaken to quantify the degree and extent of

movement anticipated.




8.0 ENVIRONMENTAL ASSESSMENT

This appraisal is generally based on the DEFRA/EA publication CLR 11 (Model Procedures for the

Management of Contaminated Land, 2004), adopting current UK practice which uses the

Source-Pathway-Receptor methodology to assess contamination risks. For a site to be designated as

contaminated a plausible linkage between any identified sources and receptors must be identified, ie

whether significant pollution linkages (SPLs) are present. In considering the potential for contamination to

cause a significant effect, the extent and nature of the potential source are assessed and

pathways/receptors identified; without an SPL there is theoretically no risk to the receptors from

contamination. The assessed risks to the various potential receptors are summarised in the tabulated

Conceptual Site Model which forms Section 8.6 of this report.

8.1 Environmental setting and context

The Site is underlain by the Taplow Gravel which has a Superficial Aquifer Designation of ‘Secondary

Aquifer – A’. The underlying London Clay has an ‘Unproductive’ Bedrock Aquifer Designation. The site

does not lie within a Source Protection Zone and there are no surface water features nearby. Environment

Agency records indicate that the nearest water abstraction point is about 650m distant.

The site is assessed as being of Low to Moderate Environmental Sensitivity.

8.2 Contamination sources and testing

The Preliminary Risk Assessment presented in Section 3.5 identified the following potential contaminative

sources:

Potential Source

Element/Compound potential

On site

Building built pre-2000 Asbestos

Made ground

Commercial public house usage

Hydrocarbons (TPH, PAH)

Heavy metals/semi metals

Inorganic or organic chemicals

Ground gas and VOCs

Off site

No significant potential sources identified

apart from historical record of nearby

substation

No significant risk of cross contamination

identified apart from possible relict PCB

contamination

Laboratory testing of three soil samples has been carried out at this stage from BH1 & TP2 to identify

whether contamination is present. The analysis was for a general range of contaminants to determine the

presence of any contamination within the made ground and top of natural soil. Possible relict PCB

contamination related to the substation noted to the south of the site will need to be addressed by further

investigation once closer access on site is available.




The results have been assessed where relevant against the DEFRA Soil Guideline Values (SGV) and

Category 4 Screening Levels (C4SLs), together with the LQM/CIEH Suitable 4 Use Level (S4UL) for Human

Health Risk Assessment in which Generic Assessment Criteria (GACs) have been derived from the current

CLEA Model (2nd Edition, 2009). For Extractable/Total Petroleum Hydrocarbons, the results have been

compared with the frequently used EA remedial target of 1,000mg/kg. The contamination testing was

carried out specifically for the purpose of providing a general guidance evaluation for the proposed

development. Reference should be made to the foreword to the appended contamination test results in

order to fully understand the context in which this discussion should be viewed.

The redevelopment will include 100% of hard cover by the new building/basement and external (beer

garden) area. We have used, where relevant, the trigger levels for a residential without home grown

produce development to assess the results of the contamination testing.

Using these criteria the following results are of note:

Lead: elevated concentrations of lead of 543mg/kg and 378mg/kg were measured in both of

the samples of made ground tested in BH1 and TP2 at 0.50m depth, when compared to the

C4SL threshold level of 310mg/kg. We note that these results were below the BGS published

‘Normal background concentrations of contaminants in England’ of 820mg/kg

Petroleum hydrocarbons: generally low in all samples

Polycyclic Aromatic Hydrocarbons (PAH): all below relevant thresholds

Asbestos: not detected in any samples

Notwithstanding these test results, the proposed scheme does not involve any effective change in usage

and thus end user contact with soil is expected to be negligible If the scheme is amended to include new

landscaped areas then we recommend that a layer of certified clean imported topsoil is placed to create a

capping layer and hence a barrier between end users and the made ground.

The implications of these results are addressed in the revised Conceptual Site Model below.

Although Asbestos-containing materials (ACM) were neither observed on site nor identified in the samples

examined, we note that buildings (especially those constructed before 2000) are a potential source of ACM.

Furthermore, any made ground, construction or demolition materials on site may also contain ACM. These

matters should be addressed in the Pe-construction H&S plan prior to any demolition or earthworks.

8.3 Ground gas/vapour monitoring

No specific gas generating uses/risks were identified by the PRA, but with ‘made ground’ being identified

as a possible source. Gas monitoring was undertaken on a single occasion following completion of the

borehole. No elevated levels of methane, carbon dioxide, carbon monoxide or hydrogen sulphide were

measured. PID readings in the borehole installations were generally <1ppm, with one measurement of

2.1ppm in BH1 on the monitoring visit. On the basis of these results, we consider that Characteristic




Situation 1 (very low risk) is appropriate (as described in CIRIA C665 “Assessing risks posed by hazardous

ground gases to buildings”, 2007) and this suggests that no gas protection measures will be required; this

should be re-assessed following any further monitoring.

8.4 Disposal of excavated soils

A rigorous hazard assessment of the results was not within the scope of our investigation, but our

preliminary conclusion from the contamination and WAC testing (where antimony was slightly elevated) is

that the made ground will probably classify as ‘non-hazardous industrial waste’ with an ‘inert’ classification

for natural soils. The localised elevated lead/PAH/antimony levels may, however, result in a more onerous

classification and early consultations should be made with appropriate waste facilities or regulators to

confirm the off-site disposal requirements.

8.5 Unexploded ordnance risks

As discussed in Section 3.3, a preliminary UXO assessment has been carried out (Ref SCL–532073) and

this identified the site to be in a high-risk area. On further research (see RPS email Appendix D) this

classification has been downgraded to an ALARP (as low as reasonably practicable) classification. A

specialist EOD engineer was therefore not required during our fieldwork but should be on call if further

intrusive work is carried out. The preliminary UXO risk report is included in Appendix D.




8.6 Refined Conceptual Site Model

Taking into account the above discussion, the assessed risks to potential receptors identified in the PRA

are summarised in the refined Conceptual Site Model (CSM) below. This includes recommendations for

appropriate mitigation measures to render any SPLs inactive and reduce the risks to receptors to acceptable

levels:

Source

Pathway Receptor Assessed risk, justification and measures to mitigate the risk

to acceptable levels

On site:

contaminated

soil/water

Ingestion &

direct contact

End user Low

Elevated concentrations of lead detected in the made ground.

The near-surface soils were free from visual/olfactory evidence

of volatile compounds/vapours; this was corroborated by

analysis (TPH, PID readings). The SPL to human health will be

inactive.

Made ground will be removed from proposed building footprint

during basement excavation. Beer garden at NE side of site will

remain as hardstanding. The SPL to human health will be

significantly reduced or rendered inactive. If scheme is amended

to include landscaped areas, then all made ground must be

removed, say to 0.60m depth, and replaced with certified clean

imported topsoil with a geofabric separator. The source and

pathway will be removed so the SPL to human health will then

be inactive.

A careful watching brief should be kept during construction and if

obvious or suspected contamination is encountered this should

be dealt with prescriptively.

Ingestion,

contact &

inhalation

Construction

workers and

third parties

Low:

Elevated Lead in made ground identified as SPL to human health.

Any residual risks to these receptors will be managed through

health & safety procedures and CDM regulations

Leaching from

contaminated

soils and

migration in

groundwater

Aquifer and

surface water

Low

100% hard cover expected by the redevelopment which will

prevent any contaminant leaching into the aquifer

100% of made ground will be removed within the building

footprint during basement excavation

Direct contact

with soil/water

Building fabric

and

infrastructure

Low:

The effects of soluble sulphates and alkali/acidic ground are

discussed in Section 6.5 of this report

Detailed assessment of soil/groundwater contamination with

respect to water supply pipes is outside the scope of this report.

See the relevant water authority requirements and UKWIR

‘Guidance for the selection of water supply pipes to be used in

brownfield sites’, 2010.




Source

Pathway Receptor Assessed risk, justification and measures to mitigate the risk

to acceptable levels

Off site:

contaminated

soil/water

(see 8.2

above)

Lateral

migration of

contaminants in

groundwater

End-user and

buildings

Low:

No contamination measured in soils which may be associated

with off-site sources.

Further testing including PCB analysis is recommended from site

area closest to recorded substation to south of site

On-site and

off-site:

ground gas &

vapour

Lateral

migration

through strata,

service runs and

cracks in

buildings

End-user and

buildings

Very Low

No significant potential gas sources were identified by the PRA.

Bulk of made ground as potential on-site source will be removed

during basement excavation.

Subsequent monitoring has revealed no elevated levels of

ground gases. The SPL from ground gas is therefore considered

to be inactive.

Radon gas protection measures not required according to

Groundsure report.

In conclusion, based upon the information reviewed and the results of the investigation, our assessment is

that the with appropriate mitigation measures, it should be possible to reduce the risks to acceptable levels.

The required mitigation measures identified above include the replacement of any made ground with

imported topsoil in landscaped areas if these are proposed outside the proposed basement area.

Limited access to the site was available and it is self-evident that there may be zones of contamination

within the site which were not encountered. A careful watching brief should be kept during construction to

ensure that any potentially contaminated soil encountered is disposed of in a safe and controlled manner.

Site workers should observe normal hygiene precautions when handling soils and if material suspected of

being contaminated is identified during construction, this should be set aside under protective cover and

further tests undertaken to verify the nature and levels of contamination present. If contamination is

present, a full site re-assessment may be required and a contingency should be in place in this regard.

9.0 ADDITIONAL INVESTIGATION

Piled foundations or a piled-raft foundation options are the likely options. In this situation additional

investigation to greater depth will be required to provide the appropriate pile design parameters. Further

contamination testing should form part of this additional work to provide additional site coverage for a

more comprehensive assessment.

i i i i i i i i i i i i i i i i i




GENERAL INFORMATION, LIMITATIONS AND EXCEPTIONS

Unless otherwise stated, our Report should be construed as being a Ground Investigation Report (GIR) as defined in BS EN1997-2. Our Report is not intended to be and should not be viewed or treated as a Geotechnical Design Report (GDR) as defined in EN1997-2. Any ‘design’ recommendations which are provided are for guidance only and are intended to allow the designer to assess the results and implications of our investigation/testing and to permit preliminary design of relevant elements of the proposed scheme.

The methods of investigation used have been chosen taking into account the constraints of the site including but not limited to access and space limitations. Where it has not been possible to reasonably use an EC7 compliant investigation technique we have adopted a practical technique to obtain indicative soil parameters and any interpretation is based upon our engineering experience and relevant published information.

The Report is issued on the condition that Soil Consultants Ltd will under no circumstances be liable for any loss arising directly or indirectly from ground conditions between the exploratory points which differ from those identified during our investigation. In addition, Soil Consultants Ltd will not be liable for any loss arising directly or indirectly from any opinion given on the possible configuration of strata both between the exploratory points and/or below the maximum depth of the investigation; such opinions, where given, are for guidance only and no liability can be accepted as to their accuracy. The results of any measurements taken may vary spatially or with time and further confirmatory measurements should be made after any significant delay in using this Report.

Comments made relating to ground-water or ground-gas are based upon observations made during our investigation unless otherwise stated. Ground-water and ground-gas conditions may vary with time from those reported due to factors such as seasonal effects, atmospheric effects and and/or tidal conditions. We recommend that if monitoring installations have been included as part of our investigation, continued monitoring should be carried out to maximise the information gained.

Specific geotechnical features/hazards such as (but not limited to) areas of root-related desiccation and dissolution features in chalk/soluble rock can exist in discrete localised areas - there can be no certainty that any or all of such features/hazards have been located, sampled or identified. Where a risk is identified the designer should provide appropriate contingencies to mitigate the risk through additional exploratory work and/or an engineered solution.

Where a specific risk of ground dissolution features has been identified in our Report (anything above a ‘low’ risk rating), reference should be made to the local building control to establish whether there are any specific local requirements for foundation design and appropriate allowances should be incorporated into the design. If such a risk assessment was not within the scope of our investigation and where it is deemed that the ground sequence may give rise to such a risk (for example near-surface chalk strata) it is recommended that an appropriate assessment should be undertaken prior to design of foundations.

Where spread foundations are used, we recommend that all excavations are inspected and approved by suitably experienced personnel; appropriate inspection records should be kept. This should also apply to any structures which are in direct contact with the soil where the soil could have a detrimental effect on performance or integrity of the structure.

Ground contamination often exists in small discrete areas - there can be no certainty that any or all such areas have been located, sampled or identified.

The findings and opinions conveyed in this Report may be based on information from a variety of sources such as previous desk studies, investigations or chemical analyses. Soil Consultants Limited cannot and does not provide any guarantee as to the authenticity, accuracy or reliability of such information from third parties; such information has not been independently verified unless stated in our Report.

Our Report is written in the context of an agreed scope of work between Soil Consultants Ltd and the Client and should not be used in any different context. In light of additional information becoming available, improved practices and changes in legislation, amendment or re-interpretation of the assessment or the Report in part or in whole may be necessary after its original publication.

Unless otherwise stated our investigation does not include an arboricultural survey, asbestos survey, ecological survey or flood risk assessment and these should be deemed to be outside the scope of our investigation.

We will identify tree and plant species if possible, but a suitably qualified arboriculturalist/botanist should be consulted to provide definitive identification




APPENDIX A

Fieldwork, in-situ testing and monitoring

Foreword Borehole record Standard Penetration Test results SPT hammer calibration certificate Trial pit record Groundwater and gas monitoring results

Laboratory testing

Index property testing Plasticity chart Unconsolidated undrained triaxial test results (QUT) Particle size distribution tests

Ground profiles

Plot of SPT ‘N’ value and undrained cohesion versus depth

Contamination and chemical testing

Foreword General soil suite WAC test results Sulphate/pH suite

Plans, drawings & photographs

Site photographs Proposed development plans and sections Site Plan Location Maps

Progress & Observations

Rotary augered hole commenced: 23/08/18

RH diameter 125mm

50 mm ID monitoring pipe installed to 6.00m

Samples & Tests

Type Depth(m)

FieldTest

Results

Strata

Depth(m)

Level(m)

10.80

10.20

9.25

8.60

7.90

6.90

5.20

4.90

Legend Strata Descriptions

MADE GROUND: asphalt (0.05m) over brick rubble (0.15m) over concreteMADE GROUND: dark brown and grey concrete rubble with sandy matrix

Firm orange brown slightly gravelly sandy clayey SILT. Gravel is fine to coarse subrounded flint

Medium dense orange brown clayey very silty gravelly SAND. Gravel is fine to coarse subrounded flint

Very dense orange brown clayey silty very sandy GRAVEL. Gravel is fine to coarse subrounded flint

Very dense brown clayey gravelly SAND. Gravel is fine to coarse subrounded flint

Very dense brown clayey silty very sandy GRAVEL. Gravel is fine to coarse subrounded flint.

Stiff brown fissured CLAY

Stiff grey fissured CLAY with occasional silt partings

Continued on next sheet

Backfill / Installation

1

2

3

4

5

6

7

8

9

PID 0.50 0.3

D 1.00PID 1.00 0.2

SPT/S 1.20 N=11

D 1.85PID 1.85 0.1

SPT/C 2.00 N=22

D 2.75PID 2.75 0.2

SPT/C 3.00 N=63

D 3.75

SPT/C 4.00 N=55

D 4.75

SPT/C 5.00 N=51

D 5.75

U 6.50

SPT/C 7.00 N=13

D 7.75

U 8.00

D 8.75

SPT/C 9.00 N=24

D 9.75

0.30

0.90

1.85

2.50

3.20

4.20

5.90

6.20

Site &Location:

Hero of Switzerland

142 Loughborough Road, London SW9 7LLBorehole No: BH1

Client: UDN Properties Ltd Coordinates: 531695E, 175965N Sheet 1 of 2

Engineer: Michal Hadi Associates Ltd Ground Level: +11.10mOD Report No: 10281/KOG

Key: U = Undisturbed B = Bulk D = Small disturbed W = Water ES = glass jar & plastic tub E = glass jar SPT/S = split spoon SPT/C = solid cone PP = Pocket Penetrometer [kg/cm²]HV = Hand Vane [kPa] PID = Photo Ionisation Detector [ppm - Isobutylene Equivalent, PhoCheck Tiger, 10.6eV lamp] * = full SPT penetration not achieved - see summary sheet

Borehole type:

Remarks: Borehole No:

BH1

Progress & Observations

RH complete: 23/08/18 RH depth: 12.00m Casing installed to 6.00m Water depth: 4.20m

Samples & Tests

Type Depth(m)

FieldTest

Results

Strata

Depth(m)

Level(m)

1.10

-0.90

Legend Strata Descriptions

Stiff grey fissured CLAY with occasional silt partings

End of hole at 12.00m

Backfill / Installation

10

11

12

13

14

15

16

17

18

19

U 10.00

D 10.75

U 11.00

D 11.55SPT/C 11.55 N=29

10.00

12.00

Site &Location:

Hero of Switzerland

142 Loughborough Road, London SW9 7LLBorehole No: BH1

Client: UDN Properties Ltd Coordinates: 531695E, 175965N Sheet 2 of 2

Engineer: Michal Hadi Associates Ltd Ground Level: +11.10mOD Report No: 10281/KOG

Key: U = Undisturbed B = Bulk D = Small disturbed W = Water ES = glass jar & plastic tub E = glass jar SPT/S = split spoon SPT/C = solid cone PP = Pocket Penetrometer [kg/cm²]HV = Hand Vane [kPa] PID = Photo Ionisation Detector [ppm - Isobutylene Equivalent, PhoCheck Tiger, 10.6eV lamp] * = full SPT penetration not achieved - see summary sheet

Borehole type:

Remarks: Borehole No:

BH1

Site & Hero of Switzerland Report

Location 142 Loughborough Road, London SW9 7LL No:

STANDARD PENETRATION TEST SUMMARY

BH Depth Test N value Blow-counts and penetration Casing Water Remarks

ID (m) type (Note b) Seating blows Test blows depth (m) depth (m)

BH1 1.20 S N=11 1 1 2 2 3 4 0.00 Dry

BH1 2.00 C N=22 3 4 4 5 5 8 0.00 Dry

BH1 3.00 C N=63 7 15 18 20 18 7 0.00 Dry

BH1 4.00 C N=55 10 14 14 12 15 14 0.00 Dry

BH1 5.00 C N=51 9 10 10 12 15 14 0.00 4.20

BH1 7.00 C N=13 3 3 3 3 4 3 6.00 Dry

BH1 9.00 C N=24 3 4 5 6 6 7 6.00 Dry

BH1 11.55 C N=29 6 6 7 7 7 8 6.00 Dry

a) Standard Penetration Test : BS EN ISO 22476:2005 Part 3

b) Where full penetration was not achieved, the total test blow-counts are reported

c) Hammer Energy Ratio, Er = 78%

10281/KOG

Site & Location Hero of Switzerland,

142 Loughborough Road, London SW9 7LL

Report No:

10281/KOG

SPT hammer energy test report

SiteLocation Hero of Switzerland


Trial Pit No:

TP 01[1 of 1]

Client:

Engineer:

UDN Properties Ltd

Michael Hadi Associates Ltd

Report No:

10281/KOG

D = small disturbed sample, B = bulk sample, HV = hand shear vane test [kPa], pp = pocket penetrometer [kg/cm2]

Date: 23rd August 2018 Groundwater details Samples

Equipment: Excavated with hand tools and breaker • Groundwater seepage met, excavation halted

Stability: Stable

Remarks: Basement level +9.0mOD Logged by: OT

PHOTOGRAPHS:

SiteLocation Hero of Switzerland


Trial Pit No:

TP 02 [1 of 1]

Client:

Engineer:

UDN Properties Ltd

Michael Hadi Associates Ltd

Report No:

10281/KOG

D = small disturbed sample, B = bulk sample, HV = hand shear vane test [kPa], pp = pocket penetrometer [kg/cm2]

Date: 23rd August 2018 Groundwater details Samples

Equipment: Excavated with hand tools • Dry D 0.50

Stability: Stable

Remarks: Ground level +11.0mOD Logged by: OT

SECTION: A – A’

PHOTOGRAPHS:

GL

0.35

Wall of Public House

TOPSOIL

Concrete

1.40

NW SE

MADE GROUND: brown silt/sand with brick rubble, occasional slate, concrete, mortar, glass and occasional flints

0.75

Unable to penetrate base of pit (due to presence of very dense gravel) or probe underneath concrete with Mackintosh probe (possible natural stratum). Foundation base not proven

Black pipe @ 50mm dia. At abut 0.70m

Pipe

0.15

Date: Monitoring equipmentInstrument: GA5000. Serial No. G505055

Barometric pressure: Calibration check details:a) Trend (24hrs): Falling Next calibration date: b) At start (mB): 2022c) At end (mB): 2022 Notes:

1)

Recorded by: TBH2)

Surface ground conditions: Dry

Weather conditions: Cloudy 3)

Ambient air temp (oC): 17

Results

Max Steady Max Steady Min Steady CO H2S10:40 0.2 0.2 1.8 1.0 16.9 18.3 0.0 0.0 2.1

(mb)5.50 0.0704/09/2018 BH1 3.95 0.10

Date Time (24hr)

Borehole ID GW depth Depth to base CH4 (%) CO2 (%) O2 (%) Highest (ppm) Emission rate Relative pressure PID (m) (m) (l/hr)

Site &Location

Results of groundwater/gas monitoring

04 Sep 18

12 Jan 19

Hero of Switzerland, 142 Loughborough Road, London SW9 7LL 10281/OT

Report No:

Barometric pressure trend and ambient air temperature is recorded from metoffice.gov.uk website on the day of the monitoring visit

Calibration check is performed at start of monitoring against ambient air and also periodically with a 5% CH4, 5% CO2 and 6% O2 gas mixture

CH4 = methane; CO2 = carbon dioxide; CO = carbon monoxide; O2 = oxygen; H2S = hydrogen sulphide

See note 2 below

Site & Report

Location No:

SUMMARY OF UNDRAINED SHEAR STRENGTH TEST RESULTS

BH ID Depth (m)

Moisture content (%)

Bulk density (Mg/m3)

Dry density (Mg/m3)

Cell pressure (kPa)

Deviator stress (kPa)

Failure strain (%)

Failure mode

Undrained cohesion (kPa)

Remarks

BH1 6.50 29 1.94 1.50 130 180 10.00 B 90

BH1 8.00 28 1.89 1.48 160 159 9.00 B 80

BH1 10.00 28 1.93 1.51 200 214 6.00 B 107

BH1 11.00 29 1.93 1.50 220 193 3.00 B 97

Testing in accordance with BS EN ISO 17892. UU = unconsolidated, undrained; MUU = multistage, unconsolidated, undrainedDate: 04 September 18

Unless stated otherwise: a) Rate of strain = 2mm/min and b) Standard latex membrame used with thickness = 0.5mm

Failure modes: B = brittle, I = intermediate, P = plastic

Hero of Switzerland10281/KOG


(Triaxial Sheet 1 of 1)

Site & Report

Location No:

SUMMARY OF CLASSIFICATION TEST RESULTS

BH ID Depth (m)

Type w (%)

wL

(%)wP

(%)Pass 425 (%)

IP

(%)Mod IP

(%)

IL

(%)LOI (%)

BH1 1.00 D 12 19 15 77** 4 3 -0.75

BH1 6.50 U 29 76 20 >95 56 0.17

BH1 8.00 U 28 76 20 >95 56 0.15

BH1 10.00 U 28 78 29 >95 49 -0.03

BH1 11.00 U 29 83 29 >95 54 0.00

Testing in accordance with BS EN ISO 17892 unless specified otherwise Date: 13 Sep 18

Modified Plasticity Index calculated in accordance with NHBC Standards Chapter 4.2 (reported if %passing 425mm <95%)

Percent passing 425mm: by estimation, by hand* or by sieving**



Description

Orange brown slightly gravelly sandy clayey silt

Grey CLAY

Grey CLAY

Grey CLAY

Grey CLAY

(Classification Sheet 1 of 1)

Site & Report

Location No:

M - SILT [plots below the A-Line}

C - CLAY [plots above the A-Line]

Classification in accordance with BS5930:2015 "Code of practice for site investigations"



Plasticity Chart

0

10

20

30

40

50

60

70

0 10 20 30 40 50 60 70 80 90 100 110 120

Pla

stic

ity

Ind

ex (

%)

Liquid Limit (%)

London Clay Terrace gravel

L - Low I - intermediate H - High V - Very high E - Extremely high

CL

CI

CH

CE

ML

MI

MV

ME

MH

Upper Plasticity range

CV

London Clay Formation Taplow Gravel

Site Report

Location No:

PARTICLE SIZE DISTRIBUTION

Hole ID: BH1 Description:Depth (m): 1.85

Sieving Sedimentation Sample proportions %Size (mm) % passing Size (mm) % passing Cobbles 0

75 100.0 32.0 26.7 Gravel 2363 100.0 23.0 26.4 Sand 3650 100.0 15.0 24.7 Silt 24

37.5 100.0 11.0 23.7 Clay 1728 100.0 7.0 2220 97.5 5.0 21 Grading analysis

14 92.8 4.0 20.1 D60 mm 0.2610 89.6 3.0 19.2 D30 mm 0.0376.3 0.0 2.0 17.5 D10 mm N/A5 0.0 1.0 17

3.35 17.5 0.3 13.9 Uniformity Coefficient2 19.2 Curvature Coefficient

1.18 20.10.6 21.0 Test method and date

0.425 22.0 Testing in accordance with BS EN ISO 17892:0.3 23.7 - Wet sieving method

0.212 24.7 - Hydrometer method0.15 26.40.063 26.7 Reporting date:



Orange brown clayey very silty very gravelly SAND

10 Sep 18

SILT

Fine Medium Coarse

SAND

Fine Medium Coarse

GRAVEL

Fine Medium CoarseCLAY COBBLES BOULDERS

0

10

20

30

40

50

60

70

80

90

100

0.001 0.01 0.1 1 10 100 1000

Perc

en

tag

e P

assin

g

%

Particle Size mm

Site Report

Location No:


Hole ID: BH1 Description:Depth (m): 3.75

Sieving Sedimentation Sample proportions %Size (mm) % passing Size (mm) % passing Cobbles 0

75 100.0 32.0 25 Gravel 4263 100.0 22.0 24.8 Sand 3050 100.0 15.0 23.4 Silt 14

37.5 100.0 11.0 22.9 Clay 1428 100.0 8.0 21.220 95.5 5.0 20.1 Grading analysis

14 84.7 4.0 18.6 D60 mm 2.8010 75.7 3.0 17.7 D30 mm 0.0896.3 0.0 2.0 15.6 D10 mm N/A5 0.0 1.0 14.4

3.35 15.6 0.3 11.1 Uniformity Coefficient2 17.7 Curvature Coefficient

1.18 18.60.6 20.1 Test method and date

0.425 21.2 Testing in accordance with BS EN ISO 17892:0.3 22.9 - Wet sieving method

0.212 23.4 - Hydrometer method0.15 24.80.063 25.0 Reporting date:



Brown clayey silty very sandy GRAVEL

10 Sep 18

SILT

Fine Medium Coarse

SAND

Fine Medium Coarse

GRAVEL


0

10

20

30

40

50

60

70

80

90

100

0.001 0.01 0.1 1 10 100 1000

Perc

en

tag

e P

assin

g

%

Particle Size mm

Site Report

Location No:


Hole ID: BH1 Description:

Depth (m): 5.75

Sieving Sedimentation Sample proportions %

Size (mm) % passing Size (mm) % passing Cobbles 0

75 100.0 25.0 16 Gravel 60

63 100.0 18.0 15.7 Sand 23

50 100.0 12.0 15 Silt 7

37.5 90.7 9.0 14.3 Clay 11

28 83.5 6.0 13.8

20 78.0 4.0 13.1 Grading analysis

14 62.9 3.0 11.9 D60 mm 12.15

10 56.0 2.0 11.2 D30 mm 0.378

6.3 0.0 1.0 10.5 D10 mm 0.001

5 0.0 0.9 9.55

3.35 0.0 0.2 7.5 Uniformity Coefficient

2 11.2 Curvature Coefficient

1.18 11.9

0.6 13.1 Test method and date

0.425 13.8 Testing in accordance with BS EN ISO 17892:

0.3 14.3 - Wet sieving method

0.212 15.0 - Hydrometer method

0.15 15.7

0.063 16.0 Reporting date:



Brown clayey silty very sandy GRAVEL

10 Sep 18

SILT

Fine Medium Coarse

SAND

Fine Medium Coarse

GRAVEL


0

10

20

30

40

50

60

70

80

90

100

0.001 0.01 0.1 1 10 100 1000

Perc

en

tag

e P

ass

ing

%

Particle Size mm

Site & Report No:

Location



Undrained cohesion and SPT-N vs depth

0 10 20 30 40 50 60 70 80 90 100

0

2

4

6

8

10

12

14

0 50 100 150 200 250 300 350 400 450 500

SPT N

Dep

th (

m)

Undrained cohesion - triaxial (kPa)

Undrained cohesion SPT 'N' value

London Clay Formation

Taplow Gravel

Made ground

Proposed basement formation

Rev: August 2009

Foreword to: CONTAMINATION TESTING AND ASSESSMENT The following statements are designed to inform and guide the Client and other potential parties intending to rely upon this report, with the express intent of protecting them from misunderstanding as to the extent and thus the potential associated risks that may result from proceeding without further evaluations or guidance. 1) Unless otherwise stated in this report, the testing of soils and waters is based on a

range of commonly occurring potential contaminants for the specific purpose of providing a general guidance evaluation for the proposed form of development. Thus, the range of potential contaminants is neither exhaustive nor specifically targeted to any previous known uses or influences upon the site.

2) The amount and scope of the testing should not be assumed to be exhaustive but has

been selected, at this stage, to provide a reasonable, general view of the site ground conditions. In many cases this situation is quite sufficient for the site to be characterised for the purposes of development and related Health and Safety matters for persons involved in or directly affected by the site development works. It must be understood, however, that in certain circumstances aspects or areas of the site may require further investigation and testing in order to fully clarify and characterise contamination issues, both for regulatory compliance and for commercial reasons.

3) The scope of the contamination testing must not automatically be regarded as being

sufficient to fully formulate a remediation scheme. For such a scheme it may be necessary to consider further testing to verify the effectiveness of the remedial work after the site has been treated. It must be understood that a remediation scheme which brings a site into a sufficient state for the proposed development (“fit for purpose”) under current legislation and published guidance, may result in some contamination being left in-situ. It is possible that forthcoming legislation may result in a site being classified by the Local Authority and assigned a “Degree of Risk” related to previous use or known contamination.

4) The scope of the environmental investigation and contamination testing must not be

automatically regarded as sufficient to satisfy the requirements in the wider environmental setting. The risks to adjacent properties and to the water environment are assessed by the regulatory authorities and there may be a requirement to carry out further exploration, testing and, possibly monitoring in the short or long term. It is not possible to sensibly predict the nature and extent of such additional requirements as these are the direct result of submissions to and liaison with the regulatory authorities. It is imperative, therefore, that such submissions and contacts are made as soon as possible, especially if there are perceived to be critical features of the site and proposed scheme, in this context.

5) New testing criteria have been implemented by the Environment Agency to enable a

waste disposal classification to be made. The date of implementation of this Waste Acceptance Criteria (WAC) testing was July 2005. It is this testing that will be used by the waste regulatory authorities, including waste disposal sites, to designate soils for disposal in landfill sites. In certain circumstances, to satisfy the waste regulations, there may be the necessity to carry out additional testing to clarify and confirm the nature of any contamination that may be present. If commercial requirements are significant then this process may also necessitate further field operations to clarify the extent of certain features. Thus, the waste classification must be obtained from the waste regulation authorities or a licensed waste disposal site and we strongly recommend that this classification is obtained as soon as possible and certainly prior to establishing any costings or procedures for this or related aspects of the scheme.

Site &

LocationHero of Switzerland140 Loughborough Road, London SW9 7LL

Report No:

10281/KOG

Site Plan

Tree information interpolated from Tree survey report Ref JSL 3129-770

Dynamic sampler borehole

Key

0 5m

Scale = 1:200@A4

3 storey block of flats

Adjacent multi-storey block of flats

Approximate outline of existing building

Grassed area

Beer Garden

Approximate outline of existing basement

TP2 BH1

Lime tree 17m

Cherry 9m

Trial pit

TP1

Paving

Concrete

Asphalt

Paved pedestrian area

Gardens

Car park/access

Site &

LocationHero of Switzerland140 Loughborough Road, London SW9 7LL

Report No:

10281/KOG

Location Plan

(Contains Ordnance Survey data © Crown copyright and database right 2018)

SITE LOCATION

~

~




APPENDIX B

GroundSure historical maps (Ref SCL-5320272) GroundSure EnviroInsight Report (Ref SCL-5320270) GroundSure GeoInsight Report (Ref SCL-5320271)




APPENDIX C

Lambeth Council Contaminated land and historical land use search report

Our Ref: ESH_CONTLAND_167 Your Ref: FAO Opher Tolkovsky Chiltern House, Earl Howe Road, Holmer Green High Wycombe, Bucks HP15 6QT 15th August 2018 Dear Mr Tolkovsky, Re: Contaminated land and historical land use search for Hero of Switzerland, 142 Loughborough Rd, SW9 7LL. Thank you for your request for information regarding records of entry in our Contaminated Land Database in respect of the above location.

We have searched our database for records we have on Hero of Switzerland, 142 Loughborough Rd, SW9 7LL and the surrounding area and there are no records of contamination. Please note that we have no enforcement concerns relating to Part IIA of the Environmental Protection Act 1990 and we do not intend to carry out any investigation under this legislation.

We have also searched information we have containing historical use and activity for the land surrounding the subject location. In light of the information provided I confirm we have no enforcement concerns relating to Part IIA of the Environmental Protection Act 1990 and we do not intend to carry out any investigation under this legislation.

Search Address Address Post Code Date Description Grid X Grid Y Grid Ref: Start

Date End Date

105 Minet Road, Camberwell

sw97uh 0

Listers Geotechnical Consultants, Lovell Ground investigation. 531850 176050A tq318760

LBL Depot 105 Minet Road, London

SW97UH 2001

planning approval granted for the change of use of industrial land currently used as a car breakers yard and artists studio into

531900M 176000M TQ318760




APPENDIX D

GroundSure Preliminary Unexploded Ordnance Risk Report (Ref SCL–532073) RPS UXO Classification Email Report dated 24 sept 2018

5 Risk of UXO based on WWII German bombing density

Crown Copyright 2018. All rights reserved. Licence Number 1000047514

Dynasafe BACTEC Limited

NEGLIGIBLE

LOW

MEDIUM

HIGH

1:20000

0 800400

Metres

Dynasafe BACTEC Limited and FIND Mapping Limited 09 Report reference: 502963

https://bombrisk.com

http://www.bactecuxo.com

http://builtby.findmaps.co.uk

http://www.ordnancesurvey.co.uk

6 Risk of UXO based on WWII German bomb strikes


Dynasafe BACTEC Limited BOMB STRIKESWITH BUFFER

1:5000

0 200100

Metres






7 Risk of UXO based on 250m gridded bomb damage


Dynasafe BACTEC Limited

LOW

MEDIUM

HIGH

V1 STRIKE

V2 STRIKE

1:5000

0 200100

Metres






8 Conclusions

Risk Levels and Recommendation

Indicative British / Allied UXO Risk

HIGHThere are significant potential sources of British / Allied UXO recorded in Dynasafe BACTEC’s historicaldatabase in proximity to the site. It is recommended that further research is undertaken to determinemore about these sources and to what degree they may have affected the site. Given the proximity andsignificance of these sources, the risk on site from UXO is considered to be High.

Indicative German UXO Risk

HIGHHistorical records indicate an overall high bombing density for the borough in which the site lies, highlevels of damage ascribed to structures in the area (serious damage to total destruction), and a bombstrike(s) recorded within 50m of the site on the London ARP Bomb Census Maps.

Where high bomb damage and bomb strikes are recorded, there is a likelihood that rubble and debris waspresent which could have obscured entry holes of UXBs.

As a result, this preliminary assessment has identified a High risk from German UXBs at this site.

ConclusionThis preliminary assessment has resulted in an overall High risk from UXO. Dynasafe BACTEC wouldrecommend that a Detailed UXO Threat Assessment Desk Top Study is undertaken for this site.

Detailed assessments are conducted offline by Dynasafe BACTEC’s researchers and use informationsuch as historical mapping, WWII-era aerial photography, written air-raid precaution records and wherenecessary local archive research to fully qualify the risk on site. Land use, changes to building layoutduring WWII and post war redevelopment will also have an impact on any remaining level of risk fromUXO. It is often possible to ‘zone’ sites into different risk categories. The lead time for a detailedassessment will vary between 3-10 working days dependent upon the complexity of the site and theadditional site specific information required.

For a quotation, or more information, please contact Dynasafe BACTEC on 01322 284 550.


1

cardiff

From: Rhys Pearson <[email protected]>

Sent: 24 September 2018 16:21To: cardiffSubject: RE: Hero of Switzerland

Good afternoon, apologies for the delayed response. Upon review of the information provided and a review of construction and intrusive works completed on site (post WWII), RPS considered the risk on site to be ALARP. As such suitable and sufficient UXO mitigation would be an on‐call Explosives Engineer. In the event that a suspect item being encountered by the workforce, RPS would have provided an Engineer to review the item and if necessary provided UXO Support. I hope the above is suitable for your report but if you need further info, please let me know. Kind Regards, Rhys

Rhys Pearson Explosives Safety Consultant RPS Energy, Explosives Engineering Services iversi e ourt eau ort ar e sto onmout s ire .nite in om

T F




APPENDIX E

Stephen Buss Environmental Consulting Ltd, Hero of Switzerland, 142 Loughborough Road, Basement Impact Assessment. Report ref. 2018-003-050-001, September 2018

Client: UDN Properties Ltd

Dated: September 2018

www.hydro-geology.co.uk

32 Port Hill Road, Shrewsbury SY3 8SA

Registered in England and Wales number 08595273

Stephen Buss Environmental Consulting Ltd

Hero of Switzerland: Basement Impact Assessment, hydrology and hydrogeology

Version control log

Document number Date Issued by Issued to Comments

2018-003-050-001 21 September 2018 Steve Buss Soil Consultants First draft


Page i

DISCLAIMER

This report has been prepared by Stephen Buss Environmental Consulting Ltd (SBEC) in its

professional capacity as hydrogeologist, in a manner consistent with the level of care and skill

ordinarily exercised by members of the geological and engineering professions practising at this

time, within the agreed scope and terms of contract, and taking account of the manpower and

resources devoted to it by agreement with its client.

The advice and opinions in this report should be read and relied on only in the context of the

report as a whole. As with any environmental appraisal or investigation, the conclusions and

observations are based on limited data. The risk of undiscovered environmental impairment of

the property cannot be ruled out. SBEC cannot therefore warrant the actual conditions at the

site and advice given is limited to those conditions for which information is held by SBEC at the

time. The findings are based on the information made available to SBEC at the date of the report

(and will have been assumed to be correct) and on current UK standards, codes, technology and

practices as at that time.

This report is provided to the client addressed above. Should the client wish to release this report

to any other third party for that party’s reliance, SBEC accepts no responsibility to any third party to whom this report or any part thereof is made known. SBEC accepts no responsibility

for any loss or damage incurred as a result, and the third party does not acquire any rights

whatsoever, contractual or otherwise, against SBEC except as expressly agreed with SBEC in

writing.

The findings do not purport to include any manner of legal advice or opinion. New information

or changes in conditions and regulatory requirements may occur in future, which will change the

conclusions presented here.


Page ii

TABLE OF CONTENTS

1. Introduction ........................................................................................................................................ 1

1.1 Background ................................................................................................................................. 1

1.2 Basement Works ......................................................................................................................... 1

1.3 Scope of Report .......................................................................................................................... 3

1.4 Authorship of Report ................................................................................................................ 3

2. Physical Setting, Hydrology and Hydrogeology ............................................................................. 4

2.1 Site History .................................................................................................................................. 4

2.2 Local Basements ......................................................................................................................... 4

2.3 Drainage and Topography ........................................................................................................ 4

2.4 Flooding ....................................................................................................................................... 6

2.5 Local Geology and Hydrogeology ........................................................................................... 7

2.6 Site Geology and Groundwater................................................................................................ 8

3. Site Conceptual Model and Impact Assessment .......................................................................... 10

3.1 Current Groundwater Conditions ......................................................................................... 10

3.2 Risk of Groundwater Flooding .............................................................................................. 10

3.3 Impact Assessment .................................................................................................................. 11

4. Conclusions ....................................................................................................................................... 12

Figures Figure 1.1 Location of Hero of Switzerland ........................................................................................... 1 Figure 1.2 Section of the proposed development .................................................................................. 2 Figure 2.1 The rivers Effra (west) and Peck (east) and Earl’s Sluice (centre) near Brixton ............. 5 Figure 2.2 Risk of surface water flooding................................................................................................ 6 Figure 2.3 Geological section NE of the Hero of Switzerland ............................................................ 8 Figure 2.4 Schematic borehole log ........................................................................................................... 9


Page 1

1. Introduction 1.1 Background This report presents the hydrology and hydrogeology components of a basement impact

assessment, to be submitted in support of a planning application for the development of the

Hero of Switzerland, Brixton, London SW9 7LL (Figure 1.1, national grid reference

TQ 3169 7595). The local planning authority is Lambeth Council.

Figure 1.1 Location of Hero of Switzerland

1.2 Basement Works The site is located between the Loughborough Road and Featley Road, in Brixton. Its

dimensions are approximately 15 m by 35 m. The Hero of Switzerland is a pub that comprises a

part two-storey building, with a cellar beneath part of the building footprint.

The site is surrounded by apartment blocks: a three-storey block with shops on the ground floor

is to the south (150-160 Loughborough Road), and to the north is an eleven-storey block

Hero of Switzerland


Page 2

(Leicester House). The front of the three-storey block is tarmacked while ground around the

eleven-storey apartments is grassed.

The ground around the site is flat. The topographic plan (by Arena Property Services Ltd)

indicate that the ground along the south western edge of the pub is at 11.0 m above Ordnance

Datum (AOD) and along the north eastern side (being the beer garden) is at 10.7 m AOD.

Internal ground floor level is about 0.3 m above the external level and the cellar is about 2.5 m

deep.

The plan for site redevelopment is to demolish the building and construct a new 13-storey

mostly residential building, with the lower two storeys under commercial use, with one basement

level. Figure 1.2 shows a section of the lower floors of the proposed building. Finished floor

level of the basement will be 3.5 m below that of the ground floor, so at a level of approximately

7.2 m AOD.

Figure 1.2 Section of the proposed development


Page 3

1.3 Scope of Report This report presents the hydrology and hydrogeology basement impact assessment development

for the development. It answers the following issues highlighted in Lambeth Council’s Draft

Basements Supplementary Planning Document1, dated October 2017:

9.16 The BIA should include:

• Detailed site specific analysis of hydrological… conditions; • Analysis of how the excavation of the basement may impact on the water table and and groundwater

flow, and whether perched water is present; • Details of how flood risk, including risk from groundwater and surface water flooding has been addressed

in the design, including details of any proposed mitigation measures; • Demonstration of how cumulative effects have been considered; • Identify the location of the development in relation to an aquifer or a water course; • Explain how it will impact on flooding and drainage including measures to reduce the risk of flooding to

the proposed basement and neighbouring properties;

This report relies on factual geological and geotechnical information presented by Soil

Consultants (2018) in report number 10281/KOG/OT.

1.4 Authorship of Report Stephen Buss Environmental Consulting Ltd was instructed in September 2018 to complete this

report.

This report has been prepared by Dr Stephen Buss MA MSc CGeol.

Dr Buss is a UK-based independent hydrogeologist with more than

18 years’ consulting experience in solving groundwater and flooding

issues for regulators, water companies and other private sector

organisations. He has completed in excess of eighty basement impact assessments, including the

surface water aspects. Dr Buss is a Chartered Geologist with the Geological Society of London. Dr Buss’s CV and publications list is available at www.hydro-geology.co.uk.

1 https://moderngov.lambeth.gov.uk/documents/s91400/

Appendix%201%20Draft%20LAMBETH%20BASEMENTS%20SPD%202017.pdf

http://www.hydro-geology.co.uk/

https://moderngov.lambeth.gov.uk/documents/s91400/Appendix%201%20Draft%20LAMBETH%20BASEMENTS%20SPD%202017.pdf

https://moderngov.lambeth.gov.uk/documents/s91400/Appendix%201%20Draft%20LAMBETH%20BASEMENTS%20SPD%202017.pdf


Page 4

2. Physical Setting, Hydrology and Hydrogeology 2.1 Site History According to historical maps (presented by Soil Consultants, 2018) the site was already built on

in 1871, and there was a small row of houses on the site off Loughborough Road. There is a pub

building a few metres north of the site. The row of houses and pub are marked on the 1938 map

but not on the 1948 map. (UXO mapping indicates a nearby V1 bomb strike.) The former pub is

mapped as a ruin on later maps.

Some smaller houses were built on the site by 1950, but these were quickly demolished and are

not shown on the 1958 map. The apartment blocks to the north and south of the site are on the

1958 map. The present pub building was built some time between 1968 and 1973-74.

There is no indication in the historical maps of the presence of springs or watercourses near the

site.

2.2 Local Basements It is believed that neither of the apartment blocks adjacent to the pub site have basements.

Planning applications for buildings adjacent to the Hero of Switzerland have been reviewed to

identify the likelihood of there being deeper basement structures. None were identified.

2.3 Drainage and Topography Elevation of Loughborough Road outside the site is 10.6 m AOD according to Environment

Agency LIDAR data at 50 cm resolution. Ground surface in the vicinity of the road slopes north

north-westwards (gradient from LIDAR data, along Loughborough Road, is about 0.007).

The site location is between the former courses of the ‘lost’ River2 Effra and the Earl’s Sluice

(Figure 2.1). These rivers have been culverted beneath the city: the River Effra beneath the

Brixton Road 500 m to the west, where ground elevation is about 8.0 m AOD; and Earl’s Sluice

probably about 550 m to the east.

The closest current surface water body (that is marked on a modern map) is the River Thames,

about 2.5 km north west of the site. There are a few isolated ponds within local parks that are

closer, but none are closer to the site than 500 m.

2 Barton, N. and Myers, S., 2016. The Lost Rivers of London. Revised and Extended Edition, Historical

Publications, Whitstable.


Page 5

Figure 2.1 The rivers Effra (west) and Peck (east) and Earl’s Sluice (centre) near Brixton

Hero of Switzerland

EARL’S SLUICE


Page 6

2.4 Flooding

2.4.1 Flooding from Rivers and Seas According to the Environment Agency’s map of flood risk for planning purposes, the site is in

flood zone 1, and therefore a flood risk assessment is not necessary on the basis of risk of river

flooding.

2.4.2 Surface Water Flooding The Lambeth Council Surface Water Management Plan

3 (SWMP) indicates that the site is not

within a critical drainage area for surface water flooding. The map of surface water flood risk

from the Environment Agency (Figure 2.2) indicates that there is a part of Featley Road that is at

high risk but this does not extend to within site boundaries. The site itself is at negligible risk of

surface water flooding (with an annual probability of less than 0.001).

Figure 2.2 Risk of surface water flooding

3 https://www.lambeth.gov.uk/sites/default/files/rr-surface-water-management-plan.pdf

https://www.lambeth.gov.uk/sites/default/files/rr-surface-water-management-plan.pdf


Page 7

2.4.3 Sewer Flooding According to the SWMP the site is not in one of the postcode areas with significant history of

sewer flooding, so the risk of sewer flooding can be considered to be negligible.

2.4.4 Groundwater Flooding The site is in an area listed as having ‘increased potential for elevated groundwater in permeable

superficial deposits’ by the SWMP. The likelihood of this hazard being realised is discussed in

Section 3.2. There are, however, no cited records of groundwater flooding on or near

Loughborough Road.

2.5 Local Geology and Hydrogeology Geological mapping indicates that bedrock at the site comprises London Clay which locally

isolates the main drinking water supply aquifer of the London Basin from the surface. The depth

of the chalk aquifer here is about 50 m based on data from a deep borehole at King’s College Hospital

4, 650 m to the east.

Geological mapping shows that superficial deposits comprise sands and gravels of the Taplow

Gravel Member. A line of boreholes5, constructed in 1968 roughly along the line of Minet Road,

150 to 200 m north east of the site, shows a geological section that can be assumed to be

representative of site conditions (Figure 2.3).

The cross-section shows the gravel deposit reaching a thickness of about 4.0 m but thinning

southwards. A near-surface layer of sandy clay / clayey sand overlies the sand and gravel. The

water table is within the sand and gravel unit, about 4.0 m below ground level where present.

4 http://scans.bgs.ac.uk/sobi_scans/boreholes/597849

5 http://scans.bgs.ac.uk/sobi_scans/boreholes/597569

http://scans.bgs.ac.uk/sobi_scans/boreholes/597569


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Figure 2.3 Geological section NE of the Hero of Switzerland

2.6 Site Geology and Groundwater A ground investigation was completed on site in August 2018. The investigation is reported in

full in Soil Consultants report number 10281/KOG/OT.

One borehole (BH1) was advanced, from the beer garden north east of the building, by rotary

auger, to a depth of 12.0 m. The log shows that below 0.9 m of made ground there was a layer of

sandy clayey silt to 1.85 m depth. A layer of alternating sandy gravel and gravelly sand was found

beneath this and was 4.05 m in thickness. Therefore, London Clay was identified at a depth of

5.2 m. A schematic log is shown in Figure 2.4.

A standpipe was installed in the boreholes to 6.0 m depth, i.e. to the base of the sand and gravel

layer. Groundwater was encountered during drilling, within the sand and gravel, at about 4.2 m

depth. A rest level of 3.95 m was measured during subsequent monitoring.

Clayey sand, becoming

sandy clay to the north

Sand and gravel

London Clay

Water table

BH 504:

dry


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Figure 2.4 Schematic borehole log

Depth BH10

1

2

3

Basement FFL

Formation level Rest water 3.95 m(assumed) Water strike 4.2 m

5

6

7

11

12

Sandy GRAVEL

LONDON CLAY

MADE GROUND

Sandy clayey

SILT

Gravelly SAND

Sandy GRAVEL

Clayey gravelly

SAND


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3. Site Conceptual Model and Impact Assessment 3.1 Current Groundwater Conditions Ground beneath the development site comprises a water-bearing layer of sand and gravel, over

low permeability London Clay. When measured in August 2018, groundwater level was observed

in a standpipe at a level close to the expected formation level (Section 2.6).

At the end of a very dry summer, this measurement can be expected to be lower than peak

winter levels. By comparison with typical groundwater level ranges for West London gravels in

CIRIA (1993)6, the peak groundwater level might be expected to be perhaps 0.2 to 0.3 m above

the August 2018 level.

With one borehole, the hydraulic gradient beneath the site cannot be reliably estimated except

that it is probably roughly in the direction of the northward regional slope of the ground.

3.2 Risk of Groundwater Flooding The Lambeth SFRA presents an extract from the groundwater flood susceptibility dataset, by the

British Geological Survey (BGS), as an indication that the site is susceptible to groundwater

flooding at surface. The dataset is a useful tool for highlighting regional areas that are potentially

at risk of groundwater flooding, but at a site scale the dataset is not reliable. The following

section summarises the assumptions behind the dataset7.

The dataset represents two types of groundwater flooding: ‘clearwater’ and ‘PSD’ (permeable superficial deposits). Clearwater flooding is mapped to the outcrop areas of permeable bedrock,

such as the Chalk, much further south of Loughborough Road. The London Clay is not

considered to be permeable bedrock so the modelled groundwater flooding along the

Loughborough Road is PSD flooding.

PSD flooding arises when a river level (or the sea level for coastal sites) rises within its banks, but

there are areas behind the banks that are lower than the crest of the bank. Groundwater may

then flow through the permeable sub-surface to emerge in these hollows that are not connected

to the river by an overland flow path. This is a common phenomenon on the gravels next to the

River Thames, with PSD flooding occurring in south Oxford and in the Maidenhead area.

In creating the PSD flooding dataset the BGS did not use a) a real river dataset, and b) modelled

flood levels (e.g. Environment Agency modelled levels). Instead the survey developed a bespoke

national model of river network and flood elevations at a 50 m resolution. Topography data that

was used to compare ground level with the flood level was also at 50 m resolution (originally OS

Panorama was used, but perhaps now the more modern OS Terrain 50 is used). This resolution

is suitable for regional studies but not site-specific studies.

Loughborough Road runs roughly along the watershed between two former watercourses (the

River Effra and Earl’s Sluice) that both lie more than 500 m from the site (Section 2.3). It is not,

therefore, reasonable to expect that high river levels in either watercourse (which have, of course,

been culverted into the sewer system) will lead to groundwater levels above ground surface at

Loughborough Road.

6 CIRIA, 1993. A Study of the Impact of Urbanisation on the Thames Gravels Aquifer. CIRIA report 129

7 https://www.bgs.ac.uk/research/groundwater/datainfo/GFSD_methodology.html

https://www.bgs.ac.uk/research/groundwater/datainfo/GFSD_methodology.html


Page 11

Furthermore, the site is not in a hollow - it is on a gentle slope that falls northwards. So if

flooding was to reach the site it will be river flooding, not groundwater flooding. Environment

Agency flood risk mapping shows that this is not expected (Section 2.4.1).

3.3 Impact Assessment The highest likely groundwater level (including seasonal variation) may be c. 0.3 m, or a little

more, above formation level (Section 3.1). Typically, when a basement constructed with

impermeable material (e.g. the concrete floor slab) is placed into a permeable aquifer with

flowing groundwater, the head of groundwater rises upstream of the basement and drops

downstream of the basement. It appears likely that this will be the case.

The gradient of the water table appears to be approximately northwards but the exact

groundwater flow direction is unknown. Typically, if the system were to be modelled, and if the

basement fully penetrated the sand and gravel aquifer, the rise in groundwater level might be

expected8 to be no more than perhaps 0.4 m on the upstream edge. Since the proposed

basement extends only a very small distance below the water table (relative to the full saturated

thickness) this assumed rise will be a considerable over-estimate.

There are no basements upstream of the proposed basement at the Hero of Switzerland. Hence,

even if there was to be a change in groundwater level there is no basement to be affected. It is

unfeasible to imagine that the groundwater level might rise above ground surface in these

conditions (i.e. starting at around 4.0 m below ground).

The site entirely comprises impermeable surfaces (tarmac, paving and roof), so no water goes to

ground at present. The proposed development does not intend to change this so there will be no

downstream flooding impact from the development.

8 For example, in the ARUP (2010) guidance for subterranean development for Camden Borough Council

(paragraph 172), it is stated that: ‘The change in water levels is in proportion to the increase in the length of the

flow path. In the case of a site measuring 10 m in the direction of groundwater flow, the natural difference in

groundwater level might be one or two centimetres.’


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4. Conclusions Potential environmental impacts of basement construction at the Hero of Switzerland have been

considered. The following summary conclusions are made:

• There will no overall increase in man-made impermeable area. Therefore, the amount,

timing and quality of surface water runoff will not be reduced by the development. No

water will go to ground as a result of the basement development.

• Available geological and hydrogeological information indicates that there is a permeable

aquifer beneath the site that is water bearing. Groundwater has been detected in one site

borehole roughly at formation level of the proposed basement.

• There are no basements up hydraulic gradient from the basement so there is no risk to

adjacent basements even if groundwater levels were to rise slightly as a result of

basement construction.

• Construction methods and materials will have to take account of the likelihood of

groundwater being present just above formation level.

These conclusions are considered to be robust and no further investigations are needed to satisfy

the screening criteria for groundwater risk or flooding risk.


Appendix C – Scott White and Hookins’ Flood Risk Assessment and Drainage Strategy, dated April 2019 47 Pages including appendices

Scott White and Hookins LLP Harman House Andover Road Winchester Hampshire SO23 7BS T +44 (0)1962 844855 [email protected]

Prepared by: .............................................. Harry Hunter BEng (Hons) GMICE Reviewed by: .............................................. Richard Hemming BEng MEng CEng MICE

Flood Risk Assessment and Drainage Strategy Hero of Switzerland Loughborough Junction, London

Structural and Civil Engineering Services W02047 Hero of Switerland, Loughborough Junction, London 1 www.swh.co.uk

London Bedford

Winchester

Issue and Amendment Record:

Revision Comment/Amendment Prepared Reviewed Date 01 Preliminary for Comment Harry Hunter Richard Hemming 05/09/18 02 Minor Revisions Harry Hunter Richard Hemming 24/09/18 03 General Updates Harry Hunter Richard Hemming 26/02/19 04 Site Plan Updated Harry Hunter Richard Hemming 04/04/19 05 Drainage Strategy Updated Claire Lang Richard Hemming 05/04/19 06 Site Plan Updated Harry Hunter Richard Hemming 16/04/19


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Contents

1.0 Introduction 3 2.0 Government Policy on Flood Risk and Drainage of Development 4 3.0 Existing Site 11 4.0 Potential Flood Risks 12 5.0 Flood risk mitigation and SUDS proposals 13 6.0 Surface Water Drainage Maintenance Schedule 15 7.0 Summary and Conclusions 18 8.0 Appendices 19


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Introduction

1.1 Scott White and Hookins LLP have been instructed by Macniven Quays Ltd to undertake a

flood risk assessment of a proposed development at The Hero of Switzerland,

Loughborough Junction, London. This flood risk assessment has been produced as a

supporting document for a planning application and takes the form of a desk study.

1.2 The proposed development comprises the demolition of the existing public house, and

erection of a 13-storey building (plus basement and mezzanine floor levels and roof level

access) including a replacement public house with residential units above. The existing site

currently comprises a public house with associated external hardstanding. The development

is classed as More Vulnerable Development under the National Planning Policy Framework

(NPPF) Table 2: Flood Risk Vulnerability Classification. As such it is deemed to be an

Appropriate development for Flood Zone 1 under the NPPF Table 3: Flood Risk Vulnerability

and Flood Zone ‘Compatibility’.

1.3 A location plan is provided in Appendix A. This report considers the flood risk to the

proposed development and the impact that the development will have in relation to

flooding of adjacent areas and watercourses. It also considers any limits relating to flooding

that are likely to be imposed to allow the development to be undertaken and recommends

Sustainable Urban Drainage systems (SUDS) to control surface water runoff.

1.4 This report takes into account the requirements of NPPF, the London Development Plan,

Lambeth Borough Local Plan and is based on information received from the Environment

Agency (EA) web site.

1.5 This report is for the private and confidential use of the client and its agents and may not

be copied in whole or in part without the written permission of Scott White and Hookins

LLP.


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Government Policy on Flood Risk and Drainage of Development

2.1 The frequency and severity of river flooding is perceived to have increased in recent years

and in an attempt to mitigate the flood risk the Government published Planning Policy

Statement Note 25: Development and Flood Risk (PPS25) in December 2006. PPS25 details

the importance of the effective management and reduction of flood risk in the land use

planning process and attempts to address the issue of climate change. This has since been

updated and is set out in The National Planning Policy Framework and the supporting

technical guidance.

2.2 Traditionally surface water run-off from developments has been conveyed by pipe systems

to the nearest watercourse or sewer. This tends to increase the rate and volume of the run

off often leading to flooding downstream of the new development. Latest policy promotes

the use of sustainable urban drainage systems (SuDS) whereby the control of run off is to

be as close to source as possible. This can be achieved by utilising techniques which mimic

the natural drainage processes, the use of direct infiltration for example. The Environment

Agency will, in general, seek to restrict the allowable discharge from a new development to

that previously expected form the undeveloped land.

2.3 The requirements of the revised Building Regulations which came into force on 1st April

2002 are that adequate provision should be made for dealing with rainwater form the roofs

of buildings and certain paved areas providing access to the buildings. Run off from such

drainage systems are to be discharged to one of the following systems listed in order of

priority: -

▪ A soakaway or other infiltration system

▪ A watercourse

▪ A sewer or drain

2.4 The revised Building Regulations were drafted to reinforce the requirements for SuDS

wherever possible.

2.5 The Requirements of a Flood Risk Assessment:

A Flood Risk Assessment is required in order to ascertain whether a development will

exacerbate the risk of flooding elsewhere in the catchment or is at risk of flooding itself.

A site specific FRA is required for: -

▪ Proposals of 1 Hectare or greater situated in Flood Zone 1.

▪ New development (including minor development and change of use) located in

areas of Flood Zone 1 that have critical drainage problems

▪ New development (including minor development and change of use) located in

areas of Flood Zones 2 & 3.


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2.6 The Department for Environment, Food and Rural Affairs (DEFRA) Non-Statutory Technical

Standards for Sustainable Drainage Practice Guidance also provides guidance for the

sustainable design of drainage.

2.7 Flood Risk Outside the Development

S1 - Where the drainage system discharges to a surface water body that can

accommodate uncontrolled surface water discharges without any impact on flood risk

form that surface water body (e.g. the sea or a large estuary) the peak flow control

standards below (S2 and S3) and volume control technical standards (S4 and S5) need not

apply.

2.8 Peak Flow Control

S2 - For greenfield developments, the peak runoff rate from the development to any

highway drain, sewer or surface water body for the 1 in 1 year rainfall event and the 1 in

100 year rainfall event should never exceed the peak greenfield runoff rate for the same

event.

S3 - For developments which were previously developed, the peak runoff rate from the

development to any drain, sewer or surface water body for the 1 in 1 year rainfall event

and the 1 in 100 year rainfall event must be as close as reasonably practicable to the

greenfield runoff rate from the development for the same rainfall event, but should never

exceed the rate of discharge from the development prior to redevelopment for that event.

2.9 Volume Control

S4 - Where reasonably practicable, for greenfield development, the runoff volume from

the development to any highway drain, sewer or surface water body in the 1 in 100 year, 6

hour rainfall event should never exceed the greenfield runoff volume for the same event.

S5 - Where reasonably practicable, for developments which have been previously

developed, the runoff volume from the development to any highway drain, sewer or

surface water body in the 1 in 100 year, 6 hour rainfall event must be constrained to a

value as close as is reasonably practicable to the greenfield runoff volume for the same

event, but should never exceed the runoff volume from the development site prior to

redevelopment for that event.

S6 - Where it is not reasonably practicable to constrain the volume of runoff to any drain,

sewer or surface water body in accordance with S4 or S5 above, the runoff volume must

be discharged at a rate that does not adversely affect flood risk

2.10 Flood Risk Within the Development

S7 - The drainage system must be designed so that, unless an area is designated to hold

and/or convey water as part of the design, flooding does not occur on any part of the site

for a 1 in 30 year rainfall event.


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S8 - The drainage system must be designed so that, unless an area is designated to hold

and/or convey water as part of the design, flooding does not occur during a 1 in 100 year

rainfall event in any part of: a building (including a basement); or in any utility plant

susceptible to water (e.g. pumping station or electricity substation) within the

development.

S9 - The design of the site must ensure that, so far as is reasonably practicable, flows

resulting from rainfall in excess of a 1 in 100 year rainfall event are managed in

exceedance routes that minimise the risks to people and property.

2.11 Structural Integrity

S10 - Components must be designed to ensure structural integrity of the drainage system

and any adjacent structures or infrastructure under anticipated loading conditions over the

design life of the development taking into account the requirement for reasonable levels

of maintenance.

S11 - The materials, including products, components, fittings or naturally occurring

materials, which are specified by the designer must be of a suitable nature and quality for

their intended use.

2.12 Designing for Maintenance Considerations

S12 - Pumping should only be used to facilitate drainage for those parts of the site where

it is not reasonably practicable to drain water by gravity.

2.13 Construction

S13 - The mode of construction of any communication with an existing sewer or drainage

system must be such that the making of the communication would not be prejudicial to

the structural integrity and functionality of the sewerage or drainage system.

S14 - Damage to the drainage system resulting from associated construction activities

must be minimised and must be rectified before the drainage system is considered to be

completed.

2.14 London Local Plan Policy 5.12

Policy 5.12 of the London Local Plan seeks to address current and future flood issues and

minimise risks in a sustainable and cost-effective way.

Development proposals must comply with the flood risk assessment and management

requirement set out in the NPPF and the associated technical guidance on flood risk over the


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lifetime of the development and have regard to measures proposes in Thames Estuary 2100

(TE2100) and catchment Flood Management Plans

Developments which are required to pass the Exception Test set out in the NPPF and the

Technical Guidance will need to address flood resilient design and emergency planning by

demonstrating that:

x The development will remain safe and operational under flood conditions

x A strategy of either safe evacuation and/or safely remaining in the building is

followed under flood conditions

x Key services including electricity, water etc will continue to be provided under

flood conditions

x Buildings are designed for quick recovery following a flood

Development adjacent to flood defences will be required to protect the integrity of

existing flood defences and wherever possible should aim to be set back from the banks

of the watercourses and those defences to allow their management, maintenance and

upgrading to be undertaken in a sustainable and cost effective way.

In line with the NPPF and the Technical Guidance, boroughs should, when preparing LDFs,

utilise Strategic Flood Risk Assessments to identify areas where particular flood risk issues

exist and develop actions and policy approaches aimed at reducing these risks, particularly

through redevelopment of sites at risk of flooding and identifying specific opportunities

for flood risk management measures.

2.15 London Local Plan Policy 5.13

Development should utilise sustainable urban drainage systems (SUDS) unless there are

practical reasons for not doing so, and should aim to achieve greenfield run-off rates and


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ensure that surface water run-off is managed as close to its source as possible in line with the

following hierarchy:

x Store rainwater for later use

x Use infiltration techniques, such as porous surfaces in non-clay areas

x Attenuate rainwater in ponds or open water features for gradual release

x Attenuate rainwater by storing in tanks or released water features for gradual

release

x Discharge rainwater direct to a watercourse

x Discharge rainwater to a surface water sewer/drain

x Discharge rainwater to the combined sewer.

Drainage should be designed and implemented in ways that deliver other policy objectives of

this Plan, including water use efficiency and quality, biodiversity, amenity and recreation.

Within LDFs boroughs should, in line with the Flood and Water Management Act 2010,

utilities Surface Water Management Plans to identify areas where there are particular surface

water management issues and develop actions and policy approaches aimed at reducing

these risks.

2.16 Lambeth Borough Council Local Plan

EN 5 Flood Risk

The council will seek minimise the impact of flooding in the borough through:

x Applying a sequential, risk based approach to the location of the development to avoid

where possible, flood risk to people and property and manage any residual risk, taking

account of the impacts of climate change over the lifetime of the development;

- Steering development towards areas of lowest flood risk, both across Lambeth and

within the development site boundary, through the application of the Sequential Test in

accordance with the NPPF, taking the vulnerability of the proposed uses into account, as

set out in the Lambeth Strategic Flood Risk Assessment (SFRA);

- Ensuring development does not increase flood risk and where possible reduces flood

risk for all forms of flooding;

- Permitting appropriate development in Flood Zones 1, 2, 3a and 3b subject to meeting

the criteria set out in Annex 5; and

- Taking account of the flood risk management measures identified by the Thames

Estuary 2100 Plan.


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x All development in Flood Zones 2, 3a and 2b defined in the SFRA, or identified as at risk

of flooding from other sources, should contribute positively to actively reducing flood

risk though avoidance, reduction, management and mitigation.

x A Flood Risk Assessment will be required for major development proposals within Flood

Zone 1, all development within Flood Zones 2, 3a and 3b, or where the development

may be subject to other sources of flooding. The FRA should be proportionate with the

degree of flood risk posed to and by the proposed development; consider the impact of

climate change on flood risk to and from the development using the latest government

guidance; and take account of the advice and recommendations set out in the SFRA and

Local Flood Risk Management Strategy (LFRMS).

x FRAs must consider the risk of both on and off-site flooding to and from the

development for all sources of flooding including fluvial, tidal, surface run-off,

groundwater, ordinary watercourse, sewer and reservoir.

x For all developments, it must be demonstrated that the development will be safe, and

where required, it will reduce fluvial, tidal, surface run off and groundwater flood risk

and manage residual risks through appropriate flood risk measures, including the use of

sustainable drainage systems (SuDS) in accordance with Policy EN6. Measures to

mitigate flooding from sewers should be discussed with Thames Water Utilities Ltd. And

be included in development proposals for which this is a risk.

x Basement proposals (excluding self contained dwellings in FZ3) shall incorporate

appropriate mitigation measures to ensure the development is safe from all forms of

flooding and does not increase flood risk elsewhere.

x For developments adjacent to the River Thames, and River Graveney, maintenance,

remediation and improvements to the flood defence walls will be required where

necessary. Developments adjacent to defences and culverts should demonstrate that

their development will not undermine the structural integrity of detrimentally impact

upon its intended operation.

EN 6 Sustainable Drainage Systems and Water Management

Development proposals should:

x Maximise opportunities for restoring river channels, flood flow pathways and

floodplains to their natural state and managing surface run-off above ground and as

close o the source as possible to reduce flood risks downstream; and implement

sustainable water management through water sensitive urban design (WSUD).

x Provide compensatory storage to ensure that there is no loss in flood storage capacity

where flood storage is removed, as set out in the Strategic Food Risk Assessment

(SFRA);

x Ensure that the layout and design does not have detrimental impact on floodwater flow

routes across the site;

x Demonstrate that there will be a net decrease in both the volume and rate of run-off

leaving the site by incorporating sustainable drainage systems (SUDS) in line with the

London Plan drainage hierarchy and National SuDS Standards to maximise amenity and

biodiversity benefits and improve the quality of water discharges, Details submitted to

the council to demonstrate compliance with this policy should follow the design

principles within the National SuDS Standards and the current SuDS manual and


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guidance identified within the councils SFRA or Local Flood risk Management Strategy

(LFRMS).

x Seek to improve the water environment in line with the requirements of the European

Water Framework Directive 2000 and its associated legislation, and the Thames River

Basin Management Plan;

x Minimising water consumption and the pressure on the combined sewer network,

through incorporating water efficiency measures including rainwater harvesting, grey

water recycling and other innovative technologies where practical; and

x Demonstrate that the local water supply and public sewerage networks have adequate

capacity both on and off site to serve the development; where there is a capacity

problem and improvements in off site infrastructure are not programmed, the

developer will need to demonstrate that the necessary improvements will be completed

prior to occupation of the development.


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Existing Site

3.1 The site is located on land off Loughborough Road, Loughborough Junction, London. The

site is centred on grid reference TQ 31690 75951 and is approximately 0.04 hectares in size.

A location plan is given in Appendix A.

A copy of the Existing Site Layout is present in Appendix C.

3.2 The site is a Brownfield site comprising a public house and associated hard landscaping. The

developed area of the site is largely flat. Currently the site slopes from the high point of

11.62mAOD to 10.71mAOD.

3.3 A collection of high-rise residential tower blocks with associated hard and soft landscaping

are located to the north of the site. Loughborough Road is located to the east of the site,

with medium rise residential flats beyond. To the south of the site is Hero Square with

associated retail units and hard landscaping in the form of a highway layby and pedestrian

paving. Further high-rise residential tower blocks lie beyond. Medium rise residential flats

with associated hard and soft landscaping are to the west of the site. The site is accessed

from Featley Road on the western boundary of the site.

3.4 The nearest significant watercourse to the site is the River Thames approximately 2.6km

away to the north west.

3.5 Thames Water records indicate there is a public combined sewer to the east of the site

within Loughborough Road. There is another combined sewer to the south of the site within

Featley Road. Sewer record mapping can be found in Appendix B.

3.6 Currently the site is understood to drain to the public combined sewer via a gravity drainage

network.

3.7 British Geological Survey (BGS) maps indicate the site to be underlain by the London Clay

Formation with Sand and Gravel superficial deposits. On this basis it is not likely that

drainage by infiltration techniques would be possible.

3.8 The Environment Agency online groundwater mapping uses the same BGS mapping base

information and classifies the site as an Unproductive Aquifer, which is described as “These are geological strata with low permeability that have negligible significance for water supply or river base flow.”.


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Potential Flood Risks

4.1 Flood plain mapping provided by the Environment Agency (EA) indicates that the site lies in

Flood Zone 1.

Flood Zone 1 is defined as comprising ‘land assessed as having less than 1 in 1000 annual probability of river flooding (0.1%)’.

On this basis the site is considered to have a low risk of flooding and therefore does not

have to pass the Sequential or Exception Tests. See extract of Flood Map in Appendix D.

Minor flood risks to the site are considered as follows:

4.2 Fluvial

The nearest significant watercourse is the River Thames which is approximately 2.6km to

the north west of the site.

4.3 Localised flooding caused by ground water

There is no known history of flooding of the site from groundwater sources.

4.4 Localised flooding caused by overland surface water runoff

The general topography of the site is flat with levels varying by 0.91m between 10.71mAOD

to 11.62mAOD. The areas surrounding the site are at similar levels or lower and therefore

surface water runoff is not likely to affect the site. The EA ‘Risk of Flooding from Surface Water’ indicates that the site is at very low risk of flooding from surface water although both

Featley and Loughborough Road are both at risk of surface water flooding (see Appendix D). This means it has a chance of flooding of less than 1 in 1000 annual probability of river

flooding (0.1%).

The site currently drains as a brownfield site with runoff draining towards the low point

situated to the east of the site. This runoff finds its way to the low point via overland

runoff.

4.5 Other sources of flooding

There are not any canals, reservoirs or other forms of watercourse upstream of the site to

be a potential source other than those already mentioned.

Our assessment of the above flood risks indicates that the site is not within a flood risk area

and flood mitigation measures will not be required.


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Flood risk mitigation and SUDS proposals

5.1 The development is indicated as being in Flood Zone 1 on the Environment Agency Flood

map and therefore has a low risk of flooding.

5.2 The proposed development comprises the demolition of the existing public house, and

erection of a 13-storey building (plus basement and mezzanine floor levels and roof level

access) including a replacement public house with residential units above. The proposed

site layout can be found in Appendix E.

The site has a total area of 0.045ha and its development would mimic the construction

impermeable areas and result in an increase of surface water run-off.

The existing predevelopment flows are as follows: -

▪ Existing 1 in 1 year flow = 6.2 l/s

▪ Existing 1 in 30 year flow = 16.9 l/s

▪ Existing 1 in 100 year flows = 22.0 l/s

Existing run-off rates can be found in Appendix F.

In order to limit run off from the site and mitigate flood risks to areas downstream, offsite

flow rates should be limited to greenfield rates and SuDS should be used. If a ground

investigation confirms that infiltration techniques alone are feasible then these should be

adopted.

The existing average foul water discharge rates have been calculated at 0.36l/s based on

discharge units in accordance with BS EN 12056-2:2000.

It is proposed to connect the foul water network to the existing combined water manhole

on site. The foul water flows for the proposed development are approximately at 1.67l/s in

accordance with Sewers for Adoption 6th edition.

The basement is to be tanked completely to prevent any ground water ingress. Foul water

discharge from the basement is to be pumped to the proposed gravity foul water network

on the ground floor.

On the basis of the above, the following is proposed: -

▪ Surface water runoff from roof and hardstanding areas to discharge the existing

combined sewer manhole via a cellular storage attenuation tank before discharging

to the public combined sewer.

▪ Foul water network is to discharge to the existing public combined water sewer

located within Loughborough Road via the existing combined sewer manhole.


London

Bedford

Winchester

Surface Water treatment is to be provided by the various SuDS devices proposed.

Filtration Absorption Biodegradation Sedimentation Volatilisation

Piped

Network

▫

Silt Removal

Devices

▪

At a detailed design stage, other SuDS drainage features such as filter strips, rainwater

harvesting, rainwater butts, and bio retention areas could be considered.

A Proposed Drainage Strategy showing the above outline proposals is presented in

Appendix G.

5.3 To ensure drainage elements are maintained, maintenance of drainage should be covered

by a suitable management company and subject to a regular maintenance regime.

Maintenance of SuDS to be in accordance with CIRIA SuDS manual C753 where specific

intervals are advised within the document as per element type.


London

Bedford

Winchester

Surface Water Drainage Maintenance Schedule

6.1 This section sets out the inspection and maintenance requirements for long term

management of the developments surface water drainage strategy. This work is to be

undertaken by private maintenance company.

6.2 All those responsible for maintenance should take appropriate health, safety and welfare

precautions for all activities including lone working, if relevant, and risk assessments should

always be undertaken. The sites infrastructure Health and Safety File should be consulted

before carrying out any works either inside or outside of the developments boundary and

information regarding the location of existing utilities passed on to operatives.

6.3 The requirements of the Health and Safety at Work Act 1974 and The Construction (Design

and Management) Regulations 2015 should be adhered to and any residual risks identified

in the Health and Safety File should be managed and information passed on the

maintenance operatives through task specific risk assessments.

There are three types of maintenance activities associated with surface water drainage

systems.

The SuDS Manual, CIRIA C753, defines these as:

▪ Regular Maintenance – ‘basic tasks undertaken on a frequent and predictable schedule’ including vegetation management, litter and debris removal, and inspections.’

▪ Occasional Maintenance – ‘tasks that are likely to be required periodically, but on a much less frequent and predictable basis than the routine tasks (sediment removal

is an example).’ ▪ Remedial Maintenance – ‘intermittent tasks that may be required to rectify faults

associated with the system, although the likelihood of faults can be minimised by

google design. Where remedial work is found to be necessary, it is likely to be due

to site-specific characteristics or unforeseen events, and as such timings are difficult

to predict.


London

Bedford

Winchester

6.4 SuDS Components Operation and Maintenance Activities

Operation and Maintenance Activity

SuDS Component Piped Network / Inspection Chambers

Cellular / Modular Storage

Regular Maintenance Inspection ▪ ▪ Litter and Debris Removal ▪ ▫ Grass Cutting ▫ Occasional Maintenance Sediment Management ▪ ▪ Remedial Maintenance Structure Rehabilitation/

Repair ▫ ▫ ▪ Will be required ▫ May be required Extract from The SuDS Manual Table 32.1 : Typical key SuDS components

operation and maintenance activities

6.5 Piped Network / Chambers

Piped Network/Chambers Maintenance Schedule

Required Action Typical Frequency

Regular Maintenance

Inspect and identify any features that are

not operating correctly. If required take

remedial action

Monthly for three

months, then six

monthly Debris removal from catchment surface /

gratings (where may cause risks to

performance)

Monthly (and after

large storms)

Remove sediment from trapped sumps,

manholes and catchpits. Annually or as

required Remedial Maintenance Repair / rehabilitation of gratings, inlets

and outlets As required

Monitoring Inspect / check all gratings, trapped

sumps, manholes and catchpits to ensure

that they are in good condition and

operating as designed

Annually and after

large storm events

Structure Rehabilitation /

Repair

Regular Maintenance and Monitoring to

identify if repair and / or replacement of

features or pipework is required.

As required


London

Bedford

Winchester

6.6 Cellular/modular Storage

Cellular Storage Maintenance Schedule

Required Action Typical Frequency

Regular

Maintenance

Inspect and identify any features that are

not operating correctly. If required take

remedial action

Monthly for three

months, then

annually. Remove debris from catchment surface

(where may cause risks to performance)

Monthly

Remove debris from catchment surface

(where may cause risks to performance)

Annually or as

required Remedial

Maintenance

Repair / rehabilitate inlets, outlets,

overflows and vents As required

Monitoring

Inspect / check all inlets, outlets, vents

and overflows to ensure that they are in

good condition and operating as

designed

Annually and after

large storm events

Survey inside of tank for sediment build-

up and remove if necessary

Every 5 years or as

required

Structure Rehabilitation /

Repair

Regular Maintenance and Monitoring to

identify if repair and / or replacement of

storage units is required.

As required

The SuDS Manual Table 21.3: Operation and maintenance requirements for attenuation storage

tanks


London

Bedford

Winchester

Summary and Conclusions

7.1 The development lies within Flood Risk Zones 1 as indicated on the Environment Agency

flood map. On this basis the site is considered to be at a low risk of flooding.

7.2 The flood mitigation considerations in section 4.0 of this report indicate that no increase in

flood risk, either on site or downstream, has been introduced as a result of the development

and no flood risk reduction measures are required.

7.3 Surface water runoff from the proposed roof and hard standing areas will discharge to the

existing combined sewer via cellular storage crates and an existing combined sewer

manhole.

7.4 Foul water drainage is to discharge to the existing public foul water sewer located within

Loughborough Road via an existing combined sewer manhole.


London

Bedford

Winchester

Appendices

Appendix A. Site Location Plan Appendix B. Thames Water Sewer Record Mapping Appendix C. Existing Site Layout Appendix D. Environment Agency Flood Mapping Appendix E. Proposed Site Layout Appendix F. MicroDrainage Existing Site Discharge Rates Appendix G. Proposed Drainage Strategy Appendix H. MicroDrainage Storage Calculations


London

Bedford

Winchester

Appendix A Site Location Plan

(C) Openstreetmap

Site


London

Bedford

Winchester

Appendix B Thames Water Sewer Record Mapping

Thames Water Utilities Ltd, Property Searches, PO Box 3189, Slough SL1 4W, DX 151280 Slough 13 T 0845 070 9148 E [email protected] I www.thameswater-propertysearches.co.uk

Page 6 of 14

Asset Location Search Sewer Map - ALS/ALS Standard/2018_3859399

The width of the displayed area is 500 m and the centre of the map is located at OS coordinates 531669,175938 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. 100019345 Crown Copyright Reserved.

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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 871D 871C 70BH 70BI 70BJ 70DC 70DH 70DI 70DJ 71BD 70EC 71BE 71BF 70EB 71BG 71BH 70EA 70ED 71BI 70BF 70BG 70EE 8001 8101 8103 8102 8002 9104 871B 871E 871A 7701 881A 881B 981D 981B 981C 8801 8805 9902 871F 60BJ 60DD 60BH 70CC 70CB 70CA 60BI 61BB 60DH 71CD 71CF 61BA 71CC 71CE 61BJ 61BC 71CB 71CA 71BJ 6101B 61BD 61BF 61BE 61AJ 60CE 60BB 70DE 60CF 60CG 60BA 70CI 70DF 60CJ 60CH 60AJ 70CJ 70DG 60AI 60BC 60DA 60BE 70DA 60BF 60DB 70DB 60DF 70CF 70CE 60DC 60BG

n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a 10.37 9.98 9.93 9.97 10.27 n/a 10.46 n/a n/a n/a 10.71 n/a 10.51 n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a

n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a 6.76 6.24 5.68 7.1 7.45 n/a 9.79 n/a n/a 8.99 9.37 n/a 9.36 n/a n/a n/a 9.73 9.87 n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a


Page 8 of 14

Manhole Reference Manhole Cover Level Manhole Invert Level 70CD 69CA 69BJ 69CE 6905 69DD 69BI 69DC 69DB 69BH 69CD 69DA 69DF 69BG 69CC 69CJ 791A 69CI 69DE 69CH 60AC 60AD 60AB 70CG 50AE 70DD 60CI 70CH 51BI 51BJ 51BH 50BB 51BG 51CB 50AH 51BF 50BC 51CD 51BE 51BD 50BD 51BC 51AE 50AG 50AJ 51BB 51AF 50BE 51BA 61AI 61BI 60DE 6801 581C 58AJ 78AD 78AB 59BC 79BG 59BF 59BD 59BE 59CD 79BF 79BE 79BD 59CC 6903 69BD 7901 69BC 59BH 69BB 6904 69BA 69AJ 59BJ 69CF 69CB 571A 411B 411D 411C 4003 4102 4103 4004 4101 5002 4801 581A 581B 481A

n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a 11.6 n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a 12.46 n/a n/a n/a 8.15 n/a n/a 8.31 8.15 9.02 n/a n/a n/a n/a

n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a 7.89 n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a 8.69 n/a n/a n/a 6.79 6.58 6.25 6.93 6.16 7.21 7.97 n/a n/a n/a


Page 9 of 14

Manhole Reference Manhole Cover Level Manhole Invert Level 58AH 58AI 59BB 59BI 5902 5901 501B 501C 501A 4701

n/a n/a n/a n/a n/a 10.83 n/a n/a n/a 12.29

n/a n/a n/a n/a n/a 8.76 n/a n/a n/a 8.93

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 10 of 14

ALS Sewer Map Key

Foul: A sewer designed to convey waste water from domestic andindustrial sources to a treatment works.

Surface Water: A sewer designed to convey surface water (e.g. rainwater from roofs, yards and car parks) to rivers or watercourses.

Combined: A sewer designed to convey both waste water and surfacewater from domestic and industrial sources to a treatment works.

Trunk Surface Water

Storm Relief

Vent Pipe

Proposed Thames SurfaceWater Sewer

Gallery

Surface Water RisingMain

Sludge Rising Main

Vacuum

Public Sewer Types (Operated & Maintained by Thames Water)

Notes:1) All levels associated with the plans are to Ordnance Datum Newlyn.2) All measurements on the plans are metric.3) Arrows (on gravity fed sewers) or flecks (on rising mains) indicate direction of

flow.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.

Trunk Foul

Trunk Combined

Bio-solids (Sludge)

Proposed Thames WaterFoul Sewer

Foul Rising Main

Combined Rising Main

Proposed Thames WaterRising Main

Sewer FittingsA feature in a sewer that does not affect the flow in the pipe. Example: a ventis a fitting as the function of a vent is to release excess gas.

Operational ControlsA feature in a sewer that changes or diverts the flow in the sewer. Example:A hydrobrake limits the flow passing downstream.

Air Valve

Dam Chase

Fitting

Meter

Vent Column

Control Valve

Drop Pipe

Ancillary

Weir

End ItemsEnd symbols appear at the start or end of a sewer pipe. Examples: anUndefined End at the start of a sewer indicates that Thames Water has noknowledge of the position of the sewer upstream of that symbol, Outfall on asurface water sewer indicates that the pipe discharges into a stream or river.

Outfall

Undefined End

Inlet

Other SymbolsSymbols used on maps which do not fall under other general categories

Summit

Public/Private Pumping Station/

Invert Level

Change of characteristic indicator (C.O.C.I.)

Other Sewer Types (Not Operated or Maintained by Thames Water)

AreasLines denoting areas of underground surveys, etc.

Agreement

Chamber

Operational Site

Conduit Bridge

Foul Sewer

Combined Sewer

Culverted Watercourse

Surface Water Sewer

Gulley

Proposed

Abandoned Sewer

Tunnel

6) The text appearing alongside a sewer line indicates the internal diameter ofthe pipe in milimetres. Text next to a manhole indicates the manholereference number and should not be taken as a measurement. If you areunsure about any text or symbology present on the plan, please contact amember of Property Insight on 0845 070 9148.

P P

M

W


Page 11 of 14

Asset Location Search Water Map - ALS/ALS Standard/2018_3859399

The width of the displayed area is 500 m and the centre of the map is located at OS coordinates 531669, 175938. 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. 100019345 Crown Copyright Reserved.

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31

2

6

94

8

7

5

PH

Youth

Court

Viaduct

toEl

Wyck Gardens

Elmore House

Harris House

Secker House

Kemble House

St John's Church

Woolley House

Ashby House

Nevil H

ouse

Howard House

New

ark House

11

ANGELL ROAD

Hopton H

ouse

Kettleby House

Edgehill House

Newbury House

Langport House

Barrington Lodge

BARRINGTO

N ROAD

Eldon House

Games Courts

LOUGHBOROUGH ROAD

Harper H

ouse

Leicester House

9.8m

9.4m

9.9m

10

63

14

57

26

46

61

37

382842

31

32

51

2a

24

16

23

19

30

36

82

12

5043

53

17

40

18

49 41

15

71

22

54

70

6639

65

33

62

34

5245

78

13

1a

56

27

20

67

25

60

92

88

21

94

48

44

59

47

55

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8179

13.2m

12.4m 12.3m

10.1m

13.3m

LB

SL

Ps

Works

113

CLO

SE

Yard

ELA

M

Sta

165

169

167

166

173

214

244

158

156

218

227

103

239

223

213

228

142

234

150

148

215217

242

189

152

155

210

226

102

236240

168160

181

101

237

Station A

venue

HINTON ROAD

BELINDA

ROAD

167a

169a

RUPERT GARDENSM

INET R

OAD

MA

JOR

CLO

SE

RIDGW

AY R

OAD

RAT

HG

AR R

OAD

GORDON GROVE

FEATLEY RO

AD

HILDA LOCKERT WALK

STYLES GARDENS

SWINFORD GARDENS

WIC

KW

OO

D S

TRE

ET

ANGELL PARK GARDENS

6 to 9

1 to 8ST JAMES'S CRESCENT

FIV

EW

AYS

RO

AD

TCB

TCBs

Surgery

1 to 12

4 to

16

9 to 20

1 to 78

9 to 25

5 to

10

1 to 13

11 to

22

26 to 42

21 to 32

32 to 35

1a to 1h 3a to 3h

41 to

52

28 to 31

20 to 23

33 to 44

28 to

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14 to 2627 to 39

Sub Sta

House

219

to 2

23

150 to 160

Playground

St John's Angell Town

El Sub S

ta

Games Court

Primary School

Adventure Playground

Hughes Terrace

16

25

51

26

10

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12

36

46

12

46

1

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6

9

TCBs

LB

50

18

31

21

36

1

10

25

4

3

26 to 42

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17

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1

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2

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El Sub Sta

3626

38

26

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103

18

1

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21

8

5043

LB

20

25

60

14

17

10

37

78

2

6

1024

22

19

Games Courts

9

10.1mCentre

Amberley

74

35

86

25

73

225

153

154

151

238

209

63

War

rior C

ourt

Sub

Scrap

TON ROAD

1 to 3

1 to

4

1 to

4

1 to 5

MALLAM

S MEW

S

1 to 53

1 to 53

1 to 53

1 to 53

1 to 88

1 to 88

1 to 78

1 to 10

1 to 80

1 to

14

1 to 18

Mar

ston

Hou

se

Church of England

Hughes Terrace

Schoolkeepers

Henry House

59

83

reatment

12

to

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10

2

44

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71

E

to

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to

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446

28

18

1

16

to

to

38

18

15


Page 12 of 14

ALS Water Map Key

PIPE DIAMETER DEPTH BELOW GROUND

Up to 300mm (12”) 900mm (3’)

300mm - 600mm (12” - 24”) 1100mm (3’ 8”)

600mm and bigger (24” plus) 1200mm (4’)

DistributionMain: The most common pipe shown on water maps.With few exceptions, domestic connections are only made todistribution mains.

Trunk Main: A main carrying water from a source of supply to atreatmentplant or reservoir, or from one treatmentplant or reservoirto another. Also a main transferring water in bulk to smaller watermains used for supplying individual customers.

Supply Main: A supply main indicates that the water main is usedas a supply for a single property or group of properties.

Fire Main: Where a pipe is used as a fire supply, the word FIRE willbe displayed along the pipe.

Metered Pipe: A metered main indicates that the pipe in questionsupplies water for a single property or group of properties and thatquantity of water passing through the pipe is metered even thoughthere may be no meter symbol shown.

Transmission Tunnel: A very large diameter water pipe. Mosttunnels are buried very deep underground. These pipes are notexpected to affect the structural integrity of buildingsshown on themap provided.

ProposedMain: A main that is still in the planningstages or in theprocess of being laid. More details of the proposed main and itsreference number are generally included near the main.

Water Pipes (Operated & Maintained by Thames Water)

HydrantsSingle Hydrant

MetersMeter

ValvesGeneral PurposeValve

Air Valve

End ItemsٞSymbol indicating what happens at the end of

a water main.

Blank Flange

Capped End

Undefined End

Manifold

Customer Supply

Fire Supply

Emptying Pit

Operational SitesBooster Station

Other

Other (Proposed)

Pumping Station

Service Reservoir

Shaft Inspection

TreatmentWorks

Unknown

Other Symbols

Other Water Pipes (Not Operated or Maintained by Thames Water)

Data Logger

Other Water Company Main: Occasionally other water companywater pipes may overlap the border of our clean water coveragearea. These mains are denoted in purple and in most cases havethe owner of the pipe displayed along them.

Private Main: Indiates that the water main in question is not ownedby Thames Water. These mains normally have text associated withthem indicating the diameter and owner of the pipe.

3” SUPPLY

3” FIRE

3” METERED

L

CF

4”

16”

Water Tower

?

Pressure ControlValve

CustomerValve


London Bedford

Winchester

Appendix C Existing Site Layout

!

UNIDENTIFIED

HEATING PIPESSERVICE DUCTS

VAPOUR RECOVERYGAUGE LINEOFFSET FILL PIPEVENT PIPEFUEL PIPEPUMPING MAINCOMBINED DRAINAGESURFACE DRAINAGECONTAMINATED SURFACEFOUL DRAINAGEGAS PIPEWATER PIPECOMMUNICATION CABLECABLE TELEVISIONTELECOMS CABLE

ELECTRIC CABLE

UTILITY KEY

ELECTRIC & COMMS CABLE

TRAFFIC SIGNAL CABLE

SURVEY BOUNDARY

TRENCH SCARGROUND DEPRESSION

EARTHING ROD / CABLE

END OF TRACECABLE / PIPE RISER

BACKDROP / TRAPPED EXIT HEAD OF RUN / CAPPED

PIPE INLET / OUTFALLDRAINAGE VALVE


London Bedford

Winchester

Appendix D Environment Agency Flood Mapping

Flood Risk from Rivers or the Sea

Flood Risk from Surface Water


London Bedford

Winchester

Appendix E Proposed Site Layout

UP

UP

UPDN

ResidentialStaircase

flue riser

PublicHouse

dumbwaiter

1500

StoreStore

ResidentialBin Store

ResidentialLobby

Sliding doors

WC

Sliding doors

PublicHouse Bin

StoreSubstation

WORK IN PROGRESS

date revision note drawn checkedrev

N

© Gensler All rights reserved, including but not limited to The Copyright, Design and Patents Act 1988

key plan

category

project

client

2016

number rev

rev drawn checkedscale

family

project number

notes:Do not scale from drawings. All discrepancies to be reported to Gensler architect immediately.All dimensions to be verified by contractor on site prior to any works

lead consultant

consultant

title

ISSUED DATE: 13/08/18

Tel +44 (0)20 7073 9600Fax +44 (0)20 7539 1917

Aldgate House33 Aldgate High StreetLondon, EC3N 1AHUnited Kingdom

UDN Properties65 Delamere Road, HayesMiddlesex UB4 0NNUKTel 020 3726 9801

1 : 100

15/0

4/20

19 1

4:19

:31

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sler .a

d\Pr

ojects

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CA1.201

PROPOSED GROUND FLOOR PLAN

08.7369.000

Hero of SwitzerlandSW9 7LL

1 GENERAL ARRANGEMENT

200-299 ENLARGED PLANS PARTITION

02/04/19 NLLA

A 06/03/19 Draft Issue LA NLB 02/04/19 Planning Issue LA NLC 15/04/19 Planning Issue LA NL

SCALE: 1 : 100PROPOSED GROUND FLOOR1


London Bedford

Winchester

Appendix F MicroDrainage Existing Site Discharge Rates

Scott-White & Hookins Page 142 West Street W02047London House Hero of SwitzerlandCarshalton SM5 2PR Existing Runoff RatesDate 03/09/2018 16:13 Designed by HHFile W0247 Existing runoff Rates.MDX Checked byMicro Drainage Network 2018.1

STORM SEWER DESIGN by the Modified Rational Method

Design Criteria for Storm

©1982-2018 Innovyze

Pipe Sizes STANDARD Manhole Sizes STANDARD

FSR Rainfall Model - England and WalesReturn Period (years) 100 PIMP (%) 100

M5-60 (mm) 20.100 Add Flow / Climate Change (%) 0Ratio R 0.436 Minimum Backdrop Height (m) 0.200

Maximum Rainfall (mm/hr) 50 Maximum Backdrop Height (m) 1.500Maximum Time of Concentration (mins) 30 Min Design Depth for Optimisation (m) 1.200

Foul Sewage (l/s/ha) 0.000 Min Vel for Auto Design only (m/s) 1.00Volumetric Runoff Coeff. 0.750 Min Slope for Optimisation (1:X) 500

Designed with Level Soffits

Time Area Diagram for Storm

Time(mins)

Area(ha)

Time(mins)

Area(ha)

0-4 0.043 4-8 0.002

Total Area Contributing (ha) = 0.045

Total Pipe Volume (m³) = 0.532

Network Design Table for Storm

PN Length(m)

Fall(m)

Slope(1:X)

I.Area(ha)

T.E.(mins)

BaseFlow (l/s)

k(mm)

HYDSECT

DIA(mm)

Section Type AutoDesign

S1.000 22.772 0.500 45.5 0.023 4.00 0.0 0.600 o 150 Pipe/ConduitS1.001 7.313 0.320 22.9 0.022 0.00 0.0 0.600 o 150 Pipe/Conduit

Network Results Table

PN Rain(mm/hr)

T.C.(mins)

US/IL(m)

Σ I.Area(ha)

Σ BaseFlow (l/s)

Foul(l/s)

Add Flow(l/s)

Vel(m/s)

Cap(l/s)

Flow(l/s)

S1.000 50.00 4.25 10.500 0.023 0.0 0.0 0.0 1.49 26.4 3.1S1.001 50.00 4.31 10.000 0.045 0.0 0.0 0.0 2.12 37.4 6.1


Area Summary for Storm


PipeNumber

PIMPType

PIMPName

PIMP(%)

GrossArea (ha)

Imp.Area (ha)

Pipe Total(ha)

1.000 - - 100 0.023 0.023 0.0231.001 - - 100 0.022 0.022 0.022

Total Total Total0.045 0.045 0.045

Free Flowing Outfall Details for Storm

OutfallPipe Number

OutfallName

C. Level(m)

I. Level(m)

MinI. Level

(m)

D,L(mm)

W(mm)

S1.001 S 10.740 9.680 7.320 0 0

Simulation Criteria for Storm

Volumetric Runoff Coeff 0.750 Additional Flow - % of Total Flow 0.000Areal Reduction Factor 1.000 MADD Factor * 10m³/ha Storage 2.000

Hot Start (mins) 0 Inlet Coeffiecient 0.800Hot Start Level (mm) 0 Flow per Person per Day (l/per/day) 0.000

Manhole Headloss Coeff (Global) 0.500 Run Time (mins) 60Foul Sewage per hectare (l/s) 0.000 Output Interval (mins) 1

Number of Input Hydrographs 0 Number of Offline Controls 0 Number of Time/Area Diagrams 0Number of Online Controls 0 Number of Storage Structures 0 Number of Real Time Controls 0

Synthetic Rainfall Details

Rainfall Model FSR Profile Type SummerReturn Period (years) 100 Cv (Summer) 0.750

Region England and Wales Cv (Winter) 0.840M5-60 (mm) 20.100 Storm Duration (mins) 30

Ratio R 0.436


1 year Return Period Summary of Critical Results by Maximum Outflow (Rank 1) for Storm


Simulation CriteriaAreal Reduction Factor 1.000 Additional Flow - % of Total Flow 0.000

Hot Start (mins) 0 MADD Factor * 10m³/ha Storage 2.000Hot Start Level (mm) 0 Inlet Coeffiecient 0.800

Manhole Headloss Coeff (Global) 0.500 Flow per Person per Day (l/per/day) 0.000Foul Sewage per hectare (l/s) 0.000


Synthetic Rainfall DetailsRainfall Model FSR M5-60 (mm) 20.000 Cv (Summer) 0.750

Region England and Wales Ratio R 0.432 Cv (Winter) 0.840

Margin for Flood Risk Warning (mm) 300.0 DVD Status OFFAnalysis Timestep Fine Inertia Status OFF

DTS Status ON

Profile(s) Summer and WinterDuration(s) (mins) 15, 30, 60, 120, 180, 240, 360, 480, 600, 720, 960,

1440Return Period(s) (years) 1, 30, 100

Climate Change (%) 0, 0, 0

PNUS/MHName Storm

ReturnPeriod

ClimateChange

First (X)Surcharge

First (Y)Flood

First (Z)Overflow

OverflowAct.

Water Level(m)

SurchargedDepth(m)

FloodedVolume(m³)

S1.000 S1 15 Winter 1 +0% 10.537 -0.113 0.000S1.001 S2 15 Winter 1 +0% 10.045 -0.105 0.000

PNUS/MHName

Flow /Cap.

Overflow(l/s)

PipeFlow(l/s) Status

LevelExceeded

S1.000 S1 0.14 3.5 OKS1.001 S2 0.19 6.2 OK











DTS Status ON




PNUS/MHName Storm

ReturnPeriod

ClimateChange

First (X)Surcharge

First (Y)Flood

First (Z)Overflow

OverflowAct.

Water Level(m)

SurchargedDepth(m)

FloodedVolume(m³)

S1.000 S1 15 Summer 30 +0% 10.561 -0.089 0.000S1.001 S2 15 Winter 30 +0% 10.077 -0.073 0.000

PNUS/MHName

Flow /Cap.

Overflow(l/s)


LevelExceeded

S1.000 S1 0.35 8.6 OKS1.001 S2 0.53 16.9 OK











DTS Status ON




PNUS/MHName Storm

ReturnPeriod

ClimateChange

First (X)Surcharge

First (Y)Flood

First (Z)Overflow

OverflowAct.

Water Level(m)

SurchargedDepth(m)

FloodedVolume(m³)

S1.000 S1 15 Winter 100 +0% 10.570 -0.080 0.000S1.001 S2 15 Summer 100 +0% 10.092 -0.058 0.000

PNUS/MHName

Flow /Cap.

Overflow(l/s)


LevelExceeded

S1.000 S1 0.45 11.2 OKS1.001 S2 0.69 22.0 OK


London Bedford

Winchester

Appendix G Proposed Drainage Strategy

UP

UP

UP

DN

Residential

Staircas

e

flue riser Public

House

dumbwaiter

1500

Store

Store

Residential

Bin Store

Residential

Lobby

Sliding doors

WC

Sliding doors

Public

House Bin

Store

Substation

FEATLEY

ROAD

150 to 160

21

1 to 53

Leicester House

Key

Proposed FW Sewer

Proposed SW Sewer

Proposed Combined Sewer

Existing Combined Sewer

Existing FW Sewer

Existing SW Sewer

Proposed Attenuation Tank

Sewer to be Abandoned

CP004-01_FM_ST_008_D

Drn.Rev.Project

Drawing

Amendment Chkd. Appd. Date

Scale at A1 -

Client

The Hero of SwitzerlandBrixton, London

Proposed Drainage Strategy

1:

DO NOT SCALE FROM THIS DRAWING

Notes

Harman House, Andover Road, Winchester, Hampshire SO23 7BST: +44 (0)1962 844855 W: www.swh.co.uk E: [email protected]

StructuralEngineering

CivilEngineering

Sustainabilityand BREEAM

CDMConsultancy

PRELIMINARY - NOT FOR CONSTRUCTION

W02047-SWH-XX-XX-DR-C-0500-P04100

Macniven Quays Ltd

Preliminary

Project Originator Zone Level Type Role Number Rev.

P01 Preliminary HH HJH RH 04.09.18

DRAINAGE

x Any information given on this drawing regarding existing servicesis believed to be correct. The contractor must check thisinformation and determine the nature and location of other existingservices from the various statutory authorities before commencingexcavation works.

x Drainage works to be constructed in accordance with BS EN 752and Approved Document H

x All soft spots and unacceptable material encountered in drainageexcavations is to be removed and replaced with granular materialto the requirements of the building control officer.

x Pipes to be installed to manufacturers recommendations.

x Pipes under buildings to be laid to a fall of 1:40 minimum unlessnoted otherwise.

x Plastic plain wall pipes to be PVC-U to BS EN 1401-1, class SN4,with flexible joints, Kitemark certified. Structured wall plastic pipesto be to WIS 04-35-01, Kitemark certified

x Clay pipes to be vitrified clay to BS EN 295-1, with flexible joints,Kitemark certified. Clayware pipes must be extra strengthclassification protected in accordance with the specified details.

x Concrete pipes to be precast concrete to BS 5911-1 and BS EN1916, with flexible joints.

x Bedding of pipes to be in accordance with approved document H1.

x Rocker pipes with flexible joints are to be provided at a distance of150mm and 750mm from the face of construction to manholes,where pipes pass above, below or through ground beams orfoundations; at gully connections and soil stack ends.

x Manhole access covers are to be located at the outgoing side ofmanholes.

x Cover levels are to be fixed on site to suit finished levels. Coversand frames to BS EN124, Grade D to be used in areas subject toheavy vehicular loading, Grade C in areas subject to lightvehicular loading and Grade B to be used elsewhere.

GENERAL

x This drawing is to be read in conjunction with all relevantEngineers and Architects drawings and with the Specification.

x For setting out refer to Architects drawings.

x All dimensions are in millimetres and levels are in metres unlessnoted otherwise.

x Contractor to take all relevant dimensions on site. Anydiscrepancies to be advised to the Engineer.

x Contractor to check/scan for services prior to construction to avoidany damage during works.

P02 Updated To Suit Latest Site Layout HH HJH RH 26.02.19

P03 Updated To Suit Latest Site Layout CLL HJH RH 05.04.19

P04 Updated To Suit Latest Site Layout CLL HJH RH 15.04.19


London Bedford

Winchester

Appendix H MicroDrainage Attenuation Calculations

Scott-White & Hookins Page 142 West Street W02047London House Hero of SwitzerlandCarshalton SM5 2PR Attenuation CalcsDate 03/09/2018 17:45 Designed by HHFile W02047 Attenuation Calcs.SRCX Checked byMicro Drainage Source Control 2018.1

Summary of Results for 100 year Return Period (+40%)


Half Drain Time : 20 minutes.

StormEvent

MaxLevel(m)

MaxDepth(m)

MaxInfiltration

(l/s)

MaxControl(l/s)

MaxΣ Outflow(l/s)

MaxVolume(m³)

Status

15 min Summer 10.297 0.297 0.0 5.0 5.0 9.0 O K30 min Summer 10.336 0.336 0.0 5.0 5.0 10.2 O K60 min Summer 10.331 0.331 0.0 5.0 5.0 10.1 O K120 min Summer 10.266 0.266 0.0 5.0 5.0 8.1 O K180 min Summer 10.203 0.203 0.0 5.0 5.0 6.2 O K240 min Summer 10.157 0.157 0.0 5.0 5.0 4.8 O K360 min Summer 10.114 0.114 0.0 4.6 4.6 3.5 O K480 min Summer 10.097 0.097 0.0 3.8 3.8 2.9 O K600 min Summer 10.086 0.086 0.0 3.3 3.3 2.6 O K720 min Summer 10.079 0.079 0.0 2.8 2.8 2.4 O K960 min Summer 10.069 0.069 0.0 2.3 2.3 2.1 O K1440 min Summer 10.057 0.057 0.0 1.7 1.7 1.7 O K2160 min Summer 10.048 0.048 0.0 1.2 1.2 1.4 O K2880 min Summer 10.042 0.042 0.0 1.0 1.0 1.3 O K4320 min Summer 10.035 0.035 0.0 0.7 0.7 1.1 O K5760 min Summer 10.031 0.031 0.0 0.5 0.5 0.9 O K7200 min Summer 10.028 0.028 0.0 0.5 0.5 0.9 O K8640 min Summer 10.026 0.026 0.0 0.4 0.4 0.8 O K10080 min Summer 10.024 0.024 0.0 0.3 0.3 0.7 O K

15 min Winter 10.340 0.340 0.0 5.0 5.0 10.3 O K30 min Winter 10.380 0.380 0.0 5.0 5.0 11.5 O K60 min Winter 10.364 0.364 0.0 5.0 5.0 11.1 O K120 min Winter 10.261 0.261 0.0 5.0 5.0 7.9 O K180 min Winter 10.170 0.170 0.0 5.0 5.0 5.2 O K

StormEvent

Rain(mm/hr)

FloodedVolume(m³)

DischargeVolume(m³)

Time-Peak(mins)

15 min Summer 141.917 0.0 12.0 1530 min Summer 91.958 0.0 15.5 2560 min Summer 56.713 0.0 19.1 42120 min Summer 33.812 0.0 22.8 74180 min Summer 24.675 0.0 25.0 104240 min Summer 19.628 0.0 26.5 134360 min Summer 14.150 0.0 28.6 188480 min Summer 11.224 0.0 30.3 248600 min Summer 9.372 0.0 31.6 308720 min Summer 8.084 0.0 32.7 370960 min Summer 6.399 0.0 34.5 4901440 min Summer 4.596 0.0 37.2 7342160 min Summer 3.296 0.0 40.0 11002880 min Summer 2.602 0.0 42.1 14684320 min Summer 1.862 0.0 45.2 21885760 min Summer 1.467 0.0 47.5 28647200 min Summer 1.219 0.0 49.3 36488640 min Summer 1.047 0.0 50.9 440010080 min Summer 0.921 0.0 52.2 5024

15 min Winter 141.917 0.0 13.4 1630 min Winter 91.958 0.0 17.4 2660 min Winter 56.713 0.0 21.4 46120 min Winter 33.812 0.0 25.5 80180 min Winter 24.675 0.0 28.0 108




StormEvent

MaxLevel(m)

MaxDepth(m)

MaxInfiltration

(l/s)

MaxControl(l/s)

MaxΣ Outflow(l/s)

MaxVolume(m³)

Status

240 min Winter 10.121 0.121 0.0 4.8 4.8 3.7 O K360 min Winter 10.094 0.094 0.0 3.7 3.7 2.8 O K480 min Winter 10.080 0.080 0.0 2.9 2.9 2.4 O K600 min Winter 10.072 0.072 0.0 2.5 2.5 2.2 O K720 min Winter 10.066 0.066 0.0 2.1 2.1 2.0 O K960 min Winter 10.057 0.057 0.0 1.7 1.7 1.7 O K1440 min Winter 10.048 0.048 0.0 1.2 1.2 1.4 O K2160 min Winter 10.040 0.040 0.0 0.9 0.9 1.2 O K2880 min Winter 10.035 0.035 0.0 0.7 0.7 1.1 O K4320 min Winter 10.030 0.030 0.0 0.5 0.5 0.9 O K5760 min Winter 10.026 0.026 0.0 0.4 0.4 0.8 O K7200 min Winter 10.024 0.024 0.0 0.3 0.3 0.7 O K8640 min Winter 10.022 0.022 0.0 0.3 0.3 0.7 O K10080 min Winter 10.021 0.021 0.0 0.3 0.3 0.6 O K

StormEvent

Rain(mm/hr)

FloodedVolume(m³)


Time-Peak(mins)

240 min Winter 19.628 0.0 29.7 132360 min Winter 14.150 0.0 32.1 190480 min Winter 11.224 0.0 33.9 250600 min Winter 9.372 0.0 35.4 310720 min Winter 8.084 0.0 36.7 370960 min Winter 6.399 0.0 38.7 4921440 min Winter 4.596 0.0 41.7 7342160 min Winter 3.296 0.0 44.8 11002880 min Winter 2.602 0.0 47.2 14324320 min Winter 1.862 0.0 50.7 22005760 min Winter 1.467 0.0 53.2 29047200 min Winter 1.219 0.0 55.3 35768640 min Winter 1.047 0.0 57.0 440010080 min Winter 0.921 0.0 58.5 5072


Rainfall Details


Rainfall Model FSR Winter Storms YesReturn Period (years) 100 Cv (Summer) 0.750

Region England and Wales Cv (Winter) 0.840M5-60 (mm) 20.000 Shortest Storm (mins) 15

Ratio R 0.432 Longest Storm (mins) 10080Summer Storms Yes Climate Change % +40

Time Area Diagram

Total Area (ha) 0.045

TimeFrom:

(mins)To:

Area(ha)

0 4 0.045


Model Details


Storage is Online Cover Level (m) 11.200

Cellular Storage Structure

Invert Level (m) 10.000 Safety Factor 2.0Infiltration Coefficient Base (m/hr) 0.00000 Porosity 0.95Infiltration Coefficient Side (m/hr) 0.00000

Depth (m) Area (m²) Inf. Area (m²) Depth (m) Area (m²) Inf. Area (m²) Depth (m) Area (m²) Inf. Area (m²)

0.000 32.0 32.0 0.400 32.0 41.1 0.401 0.0 41.1

Hydro-Brake® Optimum Outflow Control

Unit Reference MD-SHE-0114-5000-0400-5000Design Head (m) 0.400

Design Flow (l/s) 5.0Flush-Flo™ CalculatedObjective Minimise upstream storage

Application SurfaceSump Available YesDiameter (mm) 114

Invert Level (m) 10.000Minimum Outlet Pipe Diameter (mm) 150Suggested Manhole Diameter (mm) 1200

Control Points Head (m) Flow (l/s) Control Points Head (m) Flow (l/s)

Design Point (Calculated) 0.400 5.0 Kick-Flo® 0.312 4.5Flush-Flo™ 0.169 5.0 Mean Flow over Head Range - 4.0

The hydrological calculations have been based on the Head/Discharge relationship for the Hydro-Brake®Optimum as specified. Should another type of control device other than a Hydro-Brake Optimum® beutilised then these storage routing calculations will be invalidated

Depth (m) Flow (l/s) Depth (m) Flow (l/s) Depth (m) Flow (l/s) Depth (m) Flow (l/s) Depth (m) Flow (l/s)

0.100 4.0 0.800 6.9 2.000 10.6 4.000 14.8 7.000 19.50.200 5.0 1.000 7.7 2.200 11.1 4.500 15.6 7.500 20.20.300 4.6 1.200 8.3 2.400 11.6 5.000 16.4 8.000 20.90.400 5.0 1.400 9.0 2.600 12.0 5.500 17.3 8.500 21.50.500 5.5 1.600 9.6 3.000 12.9 6.000 18.0 9.000 22.10.600 6.0 1.800 10.1 3.500 13.9 6.500 18.8 9.500 22.7


Appendix D – Scott White and Hookins’ Capacity Assessment

26 pages including appendices

Scott White and Hookins LLP Harman House Andover Road Winchester Hampshire SO23 7BS T +44 (0)1962 844855 [email protected]

Capacity Assessment Hero of Switzerland, Loughborough Junction, London Prepared by: .............................................. Harry Hunter BEng (Hons) GMICE Checked by: .............................................. Ian Llewellyn MEng (Hons) CEng MICE MIStructE

Structural and Civil Engineering Services W02047 Hero of Switzerland

London Bedford

Winchester

Contents 1.0 Introduction 2 2.0 Existing Conditions 3 3.0 Proposed Conditions 5 4.0 Summary & Conclusions 6 Appendices 7

London Bedford

Winchester


1.0 Introduction

1.1 Scott White and Hookins (SWH) have prepared this Capacity Statement for a proposed

development at The Hero of Switzerland, Brixton, London. This statement has been produced as a supporting document for a planning application and takes the form of a desk study.

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Winchester


2.0 Existing Conditions

2.1 Existing Site

2.1.1 The existing site comprises a public house with a residential flat above. Drainage serving the existing site is comprised of a combined drainage network serving both foul and surface water discharge.

2.1.2 The existing foul water drainage loadings have been calculated in accordance with BS EN 12056-2:2000.

2.1.3 A copy of the existing site layout is located in Appendix A.

2.2 Foul Water Network

2.2.1 The existing foul water loading has been calculated as follows:

The existing building use can be considered as frequent, which gives a peak foul water discharge rate of 3.00l/s.

2.3 Surface Water Network

2.3.1 The existing surface water discharge rates have been calculated by modelling the existing drainage network in MicroDrainage with the existing impermeable areas.

2.3.2 The proposed site has an area of 0.045ha, of which 100% is impermeable. Based on this, the existing brownfield runoff rates from the site are as follows:-

1 in 1 year: 6.2 l/s 1 in 30 year: 16.9 l/s 1 in 100 year : 22.0 l/s

MicroDrainage calculations for the existing surface water network are located in Appendix B.

London Bedford

Winchester


2.4 The total existing peak off site discharge for the site to the combined sewer for a 1 in 100yr storm event is therefore 25.0 l/s.

London Bedford

Winchester


3.0 Proposed Conditions

3.1 Proposed Site

3.1.1 The proposed site comprises the reconstruction of the existing public house with 36 residential apartments above over 14 stories. Drainage for the proposed site will be separated into a separate foul and surface water network before discharging into an existing combined manhole on site.

3.1.2 The proposed foul water drainage loadings have been calculated in accordance with BS EN 12056-2:2000 and Sewers for Adoption 6th Addition.

3.1.3 A copy of the proposed site layout is located in Appendix C.

3.2 Foul Water Network

3.2.1 The existing foul water loading has been calculated as follows: It is assumed the loading from the proposed public house will mimic the existing conditions and will therefore have a peak discharge rate of 3.00l/s. The foul water discharge rate for the 36 residential apartments based on SfA6, at 4000l/dwelling/day, is 1.67l/s.

3.3 Surface Water Network

3.3.1 It is proposed to restrict the surface water discharge rate from the proposed site to better the existing rates as reasonably possible. In order to avoid the risk of blockage of the flow control, it is proposed to restrict the surface water discharge rate to 5.00l/s for all storm events up to and including the 1 in 100yr storm event + 40% climate change allowance.

3.3.2 With the restricted surface water outfall, the extra volume of water is to be attenuated on site in cellular storage crates. The attenuation volume is approximately 12.8m3. MicroDrainage calculations for the proposed surface water network are located in Appendix D.

3.4 The total proposed peak off site discharge for the site to the combined sewer is therefore 9.67 l/s. This provides a betterment over the existing condition of 15.33 l/s.

London Bedford

Winchester


4.0 Summary & Conclusions

4.1 The total existing peak off site discharge for the site to the combined sewer is 25.0 l/s, comprising

3.00l/s for the peak foul water discharge and 22.0l/s for the surface water network for the 1 in 100yr storm event.

4.2 The total proposed peak off site discharge for the site to the combined sewer is therefore 9.67 l/s. This is comprised of 4.67l/s from the foul water network, and 5.00l/s from the surface water network for the 1 in 100yr storm event including 40% allowance for climate change.

4.3 This proposed development therefore provides a reduction in peak off-site surface and foul water discharge of 15.33 l/s.

4.4 The figures provided in this report were provided to Thames Water for a Pre-Planning enquiry. Thames Water have subsequently confirmed that there is sufficient capacity in the existing network to accommodate the foul and surface water discharge from the proposed development. The Pre-Planning Capacity confirmation letter is located in Appendix E.

London Bedford

Winchester


Appendices

London Bedford

Winchester


Appendix A Existing Site Layout

!

UNIDENTIFIED

HEATING PIPESSERVICE DUCTS

VAPOUR RECOVERYGAUGE LINEOFFSET FILL PIPEVENT PIPEFUEL PIPEPUMPING MAINCOMBINED DRAINAGESURFACE DRAINAGECONTAMINATED SURFACEFOUL DRAINAGEGAS PIPEWATER PIPECOMMUNICATION CABLECABLE TELEVISIONTELECOMS CABLE

ELECTRIC CABLE

UTILITY KEY

ELECTRIC & COMMS CABLE

TRAFFIC SIGNAL CABLE

SURVEY BOUNDARY

TRENCH SCARGROUND DEPRESSION

EARTHING ROD / CABLE

END OF TRACECABLE / PIPE RISER

BACKDROP / TRAPPED EXIT HEAD OF RUN / CAPPED

PIPE INLET / OUTFALLDRAINAGE VALVE

London Bedford

Winchester


Appendix B MicroDrainage Existing Surface Water Calculations


STORM SEWER DESIGN by the Modified Rational Method

Design Criteria for Storm


Pipe Sizes STANDARD Manhole Sizes STANDARD

FSR Rainfall Model - England and WalesReturn Period (years) 100 PIMP (%) 100

M5-60 (mm) 20.100 Add Flow / Climate Change (%) 0Ratio R 0.436 Minimum Backdrop Height (m) 0.200

Maximum Rainfall (mm/hr) 50 Maximum Backdrop Height (m) 1.500Maximum Time of Concentration (mins) 30 Min Design Depth for Optimisation (m) 1.200

Foul Sewage (l/s/ha) 0.000 Min Vel for Auto Design only (m/s) 1.00Volumetric Runoff Coeff. 0.750 Min Slope for Optimisation (1:X) 500

Designed with Level Soffits

Time Area Diagram for Storm

Time(mins)

Area(ha)

Time(mins)

Area(ha)

0-4 0.043 4-8 0.002

Total Area Contributing (ha) = 0.045

Total Pipe Volume (m³) = 0.532

Network Design Table for Storm

PN Length(m)

Fall(m)

Slope(1:X)

I.Area(ha)

T.E.(mins)

BaseFlow (l/s)

k(mm)

HYDSECT

DIA(mm)

Section Type AutoDesign

S1.000 22.772 0.500 45.5 0.023 4.00 0.0 0.600 o 150 Pipe/ConduitS1.001 7.313 0.320 22.9 0.022 0.00 0.0 0.600 o 150 Pipe/Conduit

Network Results Table

PN Rain(mm/hr)

T.C.(mins)

US/IL(m)

Σ I.Area(ha)

Σ BaseFlow (l/s)

Foul(l/s)

Add Flow(l/s)

Vel(m/s)

Cap(l/s)

Flow(l/s)

S1.000 50.00 4.25 10.500 0.023 0.0 0.0 0.0 1.49 26.4 3.1S1.001 50.00 4.31 10.000 0.045 0.0 0.0 0.0 2.12 37.4 6.1


Area Summary for Storm


PipeNumber

PIMPType

PIMPName

PIMP(%)

GrossArea (ha)

Imp.Area (ha)

Pipe Total(ha)

1.000 - - 100 0.023 0.023 0.0231.001 - - 100 0.022 0.022 0.022

Total Total Total0.045 0.045 0.045

Free Flowing Outfall Details for Storm

OutfallPipe Number

OutfallName

C. Level(m)

I. Level(m)

MinI. Level

(m)

D,L(mm)

W(mm)

S1.001 S 10.740 9.680 7.320 0 0

Simulation Criteria for Storm

Volumetric Runoff Coeff 0.750 Additional Flow - % of Total Flow 0.000Areal Reduction Factor 1.000 MADD Factor * 10m³/ha Storage 2.000

Hot Start (mins) 0 Inlet Coeffiecient 0.800Hot Start Level (mm) 0 Flow per Person per Day (l/per/day) 0.000

Manhole Headloss Coeff (Global) 0.500 Run Time (mins) 60Foul Sewage per hectare (l/s) 0.000 Output Interval (mins) 1


Synthetic Rainfall Details

Rainfall Model FSR Profile Type SummerReturn Period (years) 100 Cv (Summer) 0.750

Region England and Wales Cv (Winter) 0.840M5-60 (mm) 20.100 Storm Duration (mins) 30

Ratio R 0.436











DTS Status ON




PNUS/MHName Storm

ReturnPeriod

ClimateChange

First (X)Surcharge

First (Y)Flood

First (Z)Overflow

OverflowAct.

Water Level(m)

SurchargedDepth(m)

FloodedVolume(m³)

S1.000 S1 15 Winter 1 +0% 10.537 -0.113 0.000S1.001 S2 15 Winter 1 +0% 10.045 -0.105 0.000

PNUS/MHName

Flow /Cap.

Overflow(l/s)


LevelExceeded

S1.000 S1 0.14 3.5 OKS1.001 S2 0.19 6.2 OK











DTS Status ON




PNUS/MHName Storm

ReturnPeriod

ClimateChange

First (X)Surcharge

First (Y)Flood

First (Z)Overflow

OverflowAct.

Water Level(m)

SurchargedDepth(m)

FloodedVolume(m³)

S1.000 S1 15 Summer 30 +0% 10.561 -0.089 0.000S1.001 S2 15 Winter 30 +0% 10.077 -0.073 0.000

PNUS/MHName

Flow /Cap.

Overflow(l/s)


LevelExceeded

S1.000 S1 0.35 8.6 OKS1.001 S2 0.53 16.9 OK











DTS Status ON




PNUS/MHName Storm

ReturnPeriod

ClimateChange

First (X)Surcharge

First (Y)Flood

First (Z)Overflow

OverflowAct.

Water Level(m)

SurchargedDepth(m)

FloodedVolume(m³)

S1.000 S1 15 Winter 100 +0% 10.570 -0.080 0.000S1.001 S2 15 Summer 100 +0% 10.092 -0.058 0.000

PNUS/MHName

Flow /Cap.

Overflow(l/s)


LevelExceeded

S1.000 S1 0.45 11.2 OKS1.001 S2 0.69 22.0 OK

London Bedford

Winchester


Appendix C Proposed Site Layout

UP

UP

UPDN

ResidentialStaircase

flue riser

PublicHouse

dumbwaiter

1500

StoreStore

ResidentialBin Store

ResidentialLobby

Sliding doors

WC

Sliding doors

PublicHouse Bin

StoreSubstation

WORK IN PROGRESS

date revision note drawn checkedrev

N

© Gensler All rights reserved, including but not limited to The Copyright, Design and Patents Act 1988

key plan

category

project

client

2016

number rev

rev drawn checkedscale

family

project number

notes:Do not scale from drawings. All discrepancies to be reported to Gensler architect immediately.All dimensions to be verified by contractor on site prior to any works

lead consultant

consultant

title

ISSUED DATE: 13/08/18

Tel +44 (0)20 7073 9600Fax +44 (0)20 7539 1917

Aldgate House33 Aldgate High StreetLondon, EC3N 1AHUnited Kingdom

UDN Properties65 Delamere Road, HayesMiddlesex UB4 0NNUKTel 020 3726 9801

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PROPOSED GROUND FLOOR PLAN

08.7369.000

Hero of SwitzerlandSW9 7LL

1 GENERAL ARRANGEMENT

200-299 ENLARGED PLANS PARTITION

02/04/19 NLLA

A 06/03/19 Draft Issue LA NLB 02/04/19 Planning Issue LA NLC 15/04/19 Planning Issue LA NL

SCALE: 1 : 100PROPOSED GROUND FLOOR1

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Winchester


Appendix D MicroDrainage Proposed Surface Water Calculations




Half Drain Time : 20 minutes.

StormEvent

MaxLevel(m)

MaxDepth(m)

MaxInfiltration

(l/s)

MaxControl(l/s)

MaxΣ Outflow(l/s)

MaxVolume(m³)

Status

15 min Summer 10.297 0.297 0.0 5.0 5.0 9.0 O K30 min Summer 10.336 0.336 0.0 5.0 5.0 10.2 O K60 min Summer 10.331 0.331 0.0 5.0 5.0 10.1 O K120 min Summer 10.266 0.266 0.0 5.0 5.0 8.1 O K180 min Summer 10.203 0.203 0.0 5.0 5.0 6.2 O K240 min Summer 10.157 0.157 0.0 5.0 5.0 4.8 O K360 min Summer 10.114 0.114 0.0 4.6 4.6 3.5 O K480 min Summer 10.097 0.097 0.0 3.8 3.8 2.9 O K600 min Summer 10.086 0.086 0.0 3.3 3.3 2.6 O K720 min Summer 10.079 0.079 0.0 2.8 2.8 2.4 O K960 min Summer 10.069 0.069 0.0 2.3 2.3 2.1 O K1440 min Summer 10.057 0.057 0.0 1.7 1.7 1.7 O K2160 min Summer 10.048 0.048 0.0 1.2 1.2 1.4 O K2880 min Summer 10.042 0.042 0.0 1.0 1.0 1.3 O K4320 min Summer 10.035 0.035 0.0 0.7 0.7 1.1 O K5760 min Summer 10.031 0.031 0.0 0.5 0.5 0.9 O K7200 min Summer 10.028 0.028 0.0 0.5 0.5 0.9 O K8640 min Summer 10.026 0.026 0.0 0.4 0.4 0.8 O K10080 min Summer 10.024 0.024 0.0 0.3 0.3 0.7 O K

15 min Winter 10.340 0.340 0.0 5.0 5.0 10.3 O K30 min Winter 10.380 0.380 0.0 5.0 5.0 11.5 O K60 min Winter 10.364 0.364 0.0 5.0 5.0 11.1 O K120 min Winter 10.261 0.261 0.0 5.0 5.0 7.9 O K180 min Winter 10.170 0.170 0.0 5.0 5.0 5.2 O K

StormEvent

Rain(mm/hr)

FloodedVolume(m³)


Time-Peak(mins)

15 min Summer 141.917 0.0 12.0 1530 min Summer 91.958 0.0 15.5 2560 min Summer 56.713 0.0 19.1 42120 min Summer 33.812 0.0 22.8 74180 min Summer 24.675 0.0 25.0 104240 min Summer 19.628 0.0 26.5 134360 min Summer 14.150 0.0 28.6 188480 min Summer 11.224 0.0 30.3 248600 min Summer 9.372 0.0 31.6 308720 min Summer 8.084 0.0 32.7 370960 min Summer 6.399 0.0 34.5 4901440 min Summer 4.596 0.0 37.2 7342160 min Summer 3.296 0.0 40.0 11002880 min Summer 2.602 0.0 42.1 14684320 min Summer 1.862 0.0 45.2 21885760 min Summer 1.467 0.0 47.5 28647200 min Summer 1.219 0.0 49.3 36488640 min Summer 1.047 0.0 50.9 440010080 min Summer 0.921 0.0 52.2 5024

15 min Winter 141.917 0.0 13.4 1630 min Winter 91.958 0.0 17.4 2660 min Winter 56.713 0.0 21.4 46120 min Winter 33.812 0.0 25.5 80180 min Winter 24.675 0.0 28.0 108




StormEvent

MaxLevel(m)

MaxDepth(m)

MaxInfiltration

(l/s)

MaxControl(l/s)

MaxΣ Outflow(l/s)

MaxVolume(m³)

Status

240 min Winter 10.121 0.121 0.0 4.8 4.8 3.7 O K360 min Winter 10.094 0.094 0.0 3.7 3.7 2.8 O K480 min Winter 10.080 0.080 0.0 2.9 2.9 2.4 O K600 min Winter 10.072 0.072 0.0 2.5 2.5 2.2 O K720 min Winter 10.066 0.066 0.0 2.1 2.1 2.0 O K960 min Winter 10.057 0.057 0.0 1.7 1.7 1.7 O K1440 min Winter 10.048 0.048 0.0 1.2 1.2 1.4 O K2160 min Winter 10.040 0.040 0.0 0.9 0.9 1.2 O K2880 min Winter 10.035 0.035 0.0 0.7 0.7 1.1 O K4320 min Winter 10.030 0.030 0.0 0.5 0.5 0.9 O K5760 min Winter 10.026 0.026 0.0 0.4 0.4 0.8 O K7200 min Winter 10.024 0.024 0.0 0.3 0.3 0.7 O K8640 min Winter 10.022 0.022 0.0 0.3 0.3 0.7 O K10080 min Winter 10.021 0.021 0.0 0.3 0.3 0.6 O K

StormEvent

Rain(mm/hr)

FloodedVolume(m³)


Time-Peak(mins)

240 min Winter 19.628 0.0 29.7 132360 min Winter 14.150 0.0 32.1 190480 min Winter 11.224 0.0 33.9 250600 min Winter 9.372 0.0 35.4 310720 min Winter 8.084 0.0 36.7 370960 min Winter 6.399 0.0 38.7 4921440 min Winter 4.596 0.0 41.7 7342160 min Winter 3.296 0.0 44.8 11002880 min Winter 2.602 0.0 47.2 14324320 min Winter 1.862 0.0 50.7 22005760 min Winter 1.467 0.0 53.2 29047200 min Winter 1.219 0.0 55.3 35768640 min Winter 1.047 0.0 57.0 440010080 min Winter 0.921 0.0 58.5 5072


Rainfall Details


Rainfall Model FSR Winter Storms YesReturn Period (years) 100 Cv (Summer) 0.750

Region England and Wales Cv (Winter) 0.840M5-60 (mm) 20.000 Shortest Storm (mins) 15

Ratio R 0.432 Longest Storm (mins) 10080Summer Storms Yes Climate Change % +40

Time Area Diagram

Total Area (ha) 0.045

TimeFrom:

(mins)To:

Area(ha)

0 4 0.045


Model Details


Storage is Online Cover Level (m) 11.200

Cellular Storage Structure

Invert Level (m) 10.000 Safety Factor 2.0Infiltration Coefficient Base (m/hr) 0.00000 Porosity 0.95Infiltration Coefficient Side (m/hr) 0.00000

Depth (m) Area (m²) Inf. Area (m²) Depth (m) Area (m²) Inf. Area (m²) Depth (m) Area (m²) Inf. Area (m²)

0.000 32.0 32.0 0.400 32.0 41.1 0.401 0.0 41.1

Hydro-Brake® Optimum Outflow Control

Unit Reference MD-SHE-0114-5000-0400-5000Design Head (m) 0.400

Design Flow (l/s) 5.0Flush-Flo™ CalculatedObjective Minimise upstream storage

Application SurfaceSump Available YesDiameter (mm) 114

Invert Level (m) 10.000Minimum Outlet Pipe Diameter (mm) 150Suggested Manhole Diameter (mm) 1200

Control Points Head (m) Flow (l/s) Control Points Head (m) Flow (l/s)

Design Point (Calculated) 0.400 5.0 Kick-Flo® 0.312 4.5Flush-Flo™ 0.169 5.0 Mean Flow over Head Range - 4.0

The hydrological calculations have been based on the Head/Discharge relationship for the Hydro-Brake®Optimum as specified. Should another type of control device other than a Hydro-Brake Optimum® beutilised then these storage routing calculations will be invalidated

Depth (m) Flow (l/s) Depth (m) Flow (l/s) Depth (m) Flow (l/s) Depth (m) Flow (l/s) Depth (m) Flow (l/s)

0.100 4.0 0.800 6.9 2.000 10.6 4.000 14.8 7.000 19.50.200 5.0 1.000 7.7 2.200 11.1 4.500 15.6 7.500 20.20.300 4.6 1.200 8.3 2.400 11.6 5.000 16.4 8.000 20.90.400 5.0 1.400 9.0 2.600 12.0 5.500 17.3 8.500 21.50.500 5.5 1.600 9.6 3.000 12.9 6.000 18.0 9.000 22.10.600 6.0 1.800 10.1 3.500 13.9 6.500 18.8 9.500 22.7

London Bedford

Winchester


Appendix E Thames Water Capacity Confirmation Letter

Thames Water Utilities Limited – Registered Office: Clearwater Court, Vastern Road, Reading RG1 8DB Company number 02366661. VAT registration no GB 537-4569-15

Mr. Harry Hunter Scott White and Hookins LLP Harman House Andover Road SO23 7BS

DS6052898

30 October 2018

Pre-planning enquiry: Confirmation of sufficient capacity

Dear Mr. Hunter,

Thank you for providing information on your development at Hero of Switzerland, 142 Longhborough Road, Stockwell, London, SW9 7LL. Existing site is 300sqm of public house, foul discharge via gravity, existing SW rates 1 in 1: 6.2l/s, 1 in 30 16.9l/s, 1 in 100: 22l/s via existing chamber which discharges into 1140x760 combined sewer. Development proposal for retaining existing public house and proposed 36 flats, foul discharge by gravity, proposed SW rates at 5l/s via existing chamber which discharges into 1140x760 combined sewer.

We have completed the assessment of the foul water flows and surface water run-off based on the information submitted in your application with the purpose of assessing sewerage capacity within the existing Thames Water sewer network.

Foul Water

If your proposals progress in line with the details you’ve provided, we’re pleased to confirm that there will be sufficient sewerage capacity in the adjacent combined sewer network to serve your development. This confirmation is valid for 12 months or for the life of any planning approval that this information is used to support, to a maximum of three years.

You’ll need to keep us informed of any changes to your design – for example, an increase in the number or density of homes. Such changes could mean there is no longer sufficient capacity.

Surface Water

We confirm that there will be sufficient capacity in our sewerage network to accept the surface water discharge rate provided as part of the enquiry, however this does not preclude the requirement as set out by the Policy 5.13 of the London Plan.

Management of surface water from the site should follow policy 5.13 of the London Plan, development should ‘aim to achieve greenfield run-off rates’ utilising Sustainable Drainage and where this is not possible information explaining why it is not possible should be provided to both the LLFA and Thames Water.

Typically greenfield run off rates of 5l/s/ha should be aimed for using the drainage hierarchy. The hierarchy lists the preference for surface water disposal as follows; Store Rainwater for later use > Use infiltration techniques, such as porous surfaces in non-clay areas > Attenuate rainwater in ponds or open water features for gradual release > Discharge rainwater direct to a watercourse > Discharge rainwater direct to a surface water sewer/drain > Discharge rainwater to the combined sewer.

No green/blue roof proposed so could possibly restrict further.

What happens next? Please make sure you submit your connection application, giving us at least 21 days’ notice of the date you wish to make your new connection/s. If you’ve any further questions, please contact me on 0203 577 9018 / 07747 640 273.

Yours sincerely

David Stamateris

Adoptions Engineer

Thames Water

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