Southwark HAPS C0478 Dulwich Upper Wood Retaining Wall

C0478 Dulwich Upper Wood Retaining Wall Supplementary Feasibility Study & Options Report for an Off-line Wall

000

Supplementary Feasibility Study & Options Report for an Off-line Wall

London Borough of Southwark

Document Number: 60493385-C0478-REP-0003-A

01 November 2019

C0478 Dulwich Upper Wood Retaining Wall Supplementary Feasibility Study & Options Report for an Off-line Wall

Quality information

Prepared by Checked by Verified By Approved by

Robert Jackson Stephen Glenfield Douglas Prince Douglas Prince Associate Director Engineer Principal Engineer Principal Engineer

Revision History

Revision Revision date Details Authorised Name Position

A 01/11/2019 First Issue DP Douglas Prince Principal Engineer

Distribution List

# Hard Copies PDF Required Association / Company Name

N/A Yes London Borough of Southwark

Prepared for: London Bourogh of Southwark CONWAYAECOM 60493385-C0478-REP-0003-A Offline Wall Options Report ii

C0478 Dulwich Upper Wood Retaining Wall Supplementary Feasibility Study & Options Report for an Off-line Wall

Prepared for: London Borough of Southwark

Prepared by: Robert Jackson Associate Director T: 020 3043 9368 E: [email protected]

CONWAY AECOM Limited Sunley House 4 Bedford Park Surrey Croydon CRO 2AP UK

T: +44 20 8639 3500 conwayaecom.com

This document has been prepared by CONWAY AECOM Limited for the sole use of our client (the “Client”) and in accordance with generally accepted consultancy principles, the budget for fees and the terms of reference agreed between CONWAY AECOM Limited and the Client. Any information provided by third parties and referred to herein has not been checked or verified by CONWAY AECOM Limited, unless otherwise expressly stated in the document. No third party may rely upon this document without the prior and express written agreement of CONWAY AECOM Limited.

Prepared for: London Bourogh of Southwark CONWAYAECOM 60493385-C0478-REP-0003-A Offline Wall Options Report iii

C0478 Dulwich Upper Wood Retaining Wall Supplementary Feasibility Study & Options Report for an Off-line Wall

Table of Contents

Executive Summary ...... 1 1. Introduction ...... 3 1.1 Scheme ...... 3 1.2 Summary of Survey Information ...... 3 1.2.1 Topographical Survey ...... 3 1.2.2 Summary of NRSWA C2 enquiries ...... 3 1.2.3 Geotechnical Investigation ...... 4 1.2.4 Ecology ...... 4 2. Options ...... 5 2.1 General ...... 5 2.1.1 Workshop ...... 5 2.1.2 Design life and maintenance ...... 5 2.2 Summary of on-line wall design ...... 5 2.3 Off Line Wall Option 1: Construct a new wall in front of the existing wall – raise the footway above existing wall ...... 6 2.4 Offline Wall Option 2: Construct a new wall in front of the existing wall with new footway – reduced carriageway ...... 7 2.5 Offline Wall Option 3: Construct a new wall in front of the existing wall reducing the footway width...... 7 2.6 Option 4: Construct Gabion baskets in front of the existing wall ...... 8 2.7 Option 5: Construct new wall in front of the existing wall, divert footway through Woodland...... 8 3. Conclusion & Recommendations ...... 9 Appendix A General Arrangement Drawing for On-line Wall ...... 10 Appendix B Drawings for Offline Wall Options 1 & 2 ...... 11 Appendix C Risk Register ...... 12

Prepared for: London Bourogh of Southwark CONWAYAECOM 60493385-C0478-REP-0003-A Offline Wall Options Report iv

C0478 Dulwich Upper Wood Retaining Wall Supplementary Feasibility Study & Options Report for an Off-line Wall

Executive Summary

The brick retaining wall on Farquhar Road in Crystal Palace SE19, bounding the Dulwich Upper Woodland is approximately 50 m long and is in a poor state of repair, with noticeable bulging of the wall and slippages of brick work. The wall is acting as a retaining wall, whereas the original design was almost certainly intended as free standing. It is assumed that the foundations are inadequate for the lateral earth pressure being applied to the wall. A Feasibility Study & Options Report (Document number 60493385-C0478-REP-0001) was prepared by AECOM on behalf of London Borough of Southwark (LBS) for an on-line replacement wall, such that there would be no encroachment of the new wall into the highway area and therefore a “stopping-up” order would not be required. A detailed design for the preferred option, a reinforced masonry cantilever wall, was prepared. This scheme required excavation behind the existing wall and the consequent removal of 34 trees within Dulwich Upper Woodland. Therefore, London Borough of Southwark have commissioned AECOM to investigate other possible designs for the scheme that do not require removal of the trees. These new designs would necessitate construction of the replacement wall off-line, in front of the existing wall. This report presents the findings of that investigation and is supplementary to the original Feasibility Study & Options Report. Five options for off-line construction of the replacement wall were presented to LBS at a workshop. Three options were dismissed:

• Construction of an L-shaped stabilising wall in reinforced concrete in front of the existing wall – this would require piles to stabilise the wall and would therefore be uneconomical and access for the piling rig would require cutting-back of the tress canopy at the front of the woodland; • Construction of a stabilising wall in front of the existing wall with gabion baskets is not recommended due to the risk of vandalism or theft and the reduced design life of such a structure; and • Construction of a path diversion through the woods is not recommended due principally to the risks to personal safety introduced by separation of the path from the highway.

The relative advantages and disadvantages of the two remaining technically feasible off-line wall options and on-line wall option designed previously are summarised in the table below:

On-line Wall Option Off-line Wall Option 1 Off-line Wall Option 2

Description Wall reconstructed on the Existing wall remains in Existing wall remains in line of the original. place, but a new off-line wall place, but a new off-line wall is constructed in front of the is constructed in front of the existing. Footway will be existing. Footway will be diverted onto top of the new diverted in front of new wall wall with a new ramp and & the carriageway width will stairs at north end of wall. be reduced.

Prepared for: London Bourogh of Southwark CONWAYAECOM 60493385-C0478-REP-0003-A Offline Wall Options Report 1

C0478 Dulwich Upper Wood Retaining Wall Supplementary Feasibility Study & Options Report for an Off-line Wall

Status of Design Construction design The current design is at the The current design is at the completed feasibility stage. Detailed feasibility stage. Detailed design of the new ramps and design of new wall is adaption of existing wall with required because this wall design of new wall will be design will be lower than the required. An additional on-line option. topographical survey will be required for the design and construction of the new

ramps.

Footway 2.0 m minimum, as existing 2.0 m width. The ramps and 2.0 m width. Small increase situation stairs at north end may in path length but no disincentivise use – alternative “short cut” particularly at night. available. Little potential for Possibility of pedestrians misuse. using cycleway as this is closer to pedestrian “desire line”.

Future cycleway 2.0 m 2.0 m 2.0 m width

Carriageway width 7.0 m 8.0 m 6.0 m (After cycleway introduced)

“Stopping-up” of No. No. Yes. highway required?

Trees affected 34 to be removed To be confirmed if option None required for (estimated) progressed to detailed construction but vegetation design but estimated to be will need to be managed less than 34. behind the proposed wall to prevent on-going damage.

Effect on utility Minimal – protection may Diversion of Openreach Diversion of Openreach company plant be required during works. cables, Thames Water Main cables, Thames Water Main and UKPN cables (street and UKPN cables (street lighting power) lighting power)

Existing wall Demolished Left in place and buried. Left in place and buried. Pilasters demolished. Pilasters demolished.

It is recommended that these options are reviewed by LBS, in conjunction with the cost estimates to be provided separately and a preferred solution identified.

Prepared for: London Bourogh of Southwark CONWAYAECOM 60493385-C0478-REP-0003-A Offline Wall Options Report 2

C0478 Dulwich Upper Wood Retaining Wall Supplementary Feasibility Study & Options Report for an Off-line Wall

1. Introduction

1.1 Scheme

The brick retaining wall on Farquhar Road in Crystal Palace SE19, bounding the Dulwich Upper Woodland is approximately 50 m long and is in a poor state of repair, with noticeable bulging of the wall and slippages of brick work. The wall is acting as a retaining wall, whereas the original design was almost certainly intended as free standing. It is assumed that the foundations are inadequate for the lateral earth pressure being applied to the wall. A Feasibility Study & Options Report (Document number 60493385-C0478-REP-0001) was prepared by AECOM on behalf of London Borough of Southwark (LBS) for an on-line replacement wall, such that there would be no encroachment of the new wall into the highway area and therefore a “stopping-up” order would not be required. A detailed design for the preferred option, a reinforced masonry cantilever wall, was prepared. This scheme required excavation behind the existing wall and the consequent removal of 34 trees within Dulwich Upper Woodland. Therefore, London Borough of Southwark have commissioned AECOM to investigate other possible designs for the scheme that do not require removal of the trees. These new designs would necessitate construction of the replacement wall off-line, in front of the existing wall. This report presents the findings of that investigation and is supplementary to the original Feasibility Study & Options Report. Cost estimates for the viable options are reported separately.

1.2 Summary of Survey Information

The results of the surveys undertaken for the original feasibility study and detailed design of the on-line wall are summarised below.

1.2.1 Topographical Survey

A topographical survey of the wall and the surrounding area, according to the specification document 60493385-C0478-SPC-0001 has been undertaken. The mapping resulting from the survey has been used in the detailed design of the on-line wall option and in the preparation of the preliminary designs for off-line wall options 1 & 2. No additional topographical survey was undertaken as part of this supplementary options study. Locations where it would be necessary to undertake additional topographical investigations to complete detailed design of a particular option have been been identified in the relevant sections below.

1.2.2 Summary of NRSWA C2 enquiries

Thames Water responded that a 4” diameter water main is located in footway adjacent to the wall. UKPN reported the existence of a power cable suppling street lighting within the footway. BT Openreach reported the existence of their cables in the footpath.

Prepared for: London Bourogh of Southwark CONWAYAECOM 60493385-C0478-REP-0003-A Offline Wall Options Report 3

C0478 Dulwich Upper Wood Retaining Wall Supplementary Feasibility Study & Options Report for an Off-line Wall

1.2.3 Geotechnical Investigation

A ground investigation was undertaken for detailed design of the on-line replacement wall. This is considered adequate for design of the off-line options. Based on the findings of the GIR, the following soil profile is assumed:

Stratum Max. Depth (m BGL)

Made Ground 0.35 below pavement level

Head deposits 4.4

London Clay Formation Confirmed to 5m in recent GI

The following properties for the strata encountered at the site are as follows:

k c u ’ k ′ c v ’ k c′ ’k Stratum (kNm-3) (kPa) (º) (kPa)

Made Ground 18 40 20 0

Head deposits 18 40 22 0

London Clay Formation 20 75 23 0

The bottom of foundation level will be such that the base of the wall is within the Head deposits. The shallowest groundwater level encountered during the historic ground investigations was 0.8 m below ground level and this will be conservatively adopted for design purposes. The position of the utilities within the footway was confirmed by slit trenching during the site investigation; plant diversions were not required for the on-line wall scheme.

1.2.4 Ecology

A preliminary ecological assessment was made following a walk-over of the site. Three trees were identifies as offering low suitability to nesting bats. Therefore, Ivy at the base of the tress should be cut at least two weeks before felling to ensure die back and aid subsequent inspection of any potential roosting features present underneath the ivy. If features are found to be present, then they will require inspection by a tree climber under supervision of an ecologist. If no suitable features are present underneath the ivy the felling can proceed as usual. However, if a bat is found during works at any time, then works to that tree must stop immediately and a licensed bat worker consulted for further advice. Rhododendron ponticum was noted with the vegetation due to be cleared. It is recommended that the Level & Mulch technique is used to remove and dispose of this plant, if required.

Prepared for: London Bourogh of Southwark CONWAYAECOM 60493385-C0478-REP-0003-A Offline Wall Options Report 4

C0478 Dulwich Upper Wood Retaining Wall Supplementary Feasibility Study & Options Report for an Off-line Wall

2. Options

2.1 General

2.1.1 Workshop

A workshop was held at the Southwark Council Offices on 4th October 2019. The options presented in the workshop are discussed below. Attendees at the workshop were as follows:

Name Organisation Role

Tony Davis LBS Streets Structures Manager

Kalsuma Begum LBS Streets Apprentice Engineer

Adolpho Gonzalez LBS Parks Arboricultural Officer

Ionut Istrati ConwayAECOM Contract Manager

Douglas Prince ConwayAECOM Design Team Project Manager

Robert Jackson ConwayAECOM Project Lead Designer

2.1.2 Design life and maintenance

Options are required to achieve a 120-year design life and be robust against theft and vandalism. It is noted that there is not a problem with graffiti on the existing wall and therefore anti-graffiti coatings are not considered necessary. Options 1-5 presented below, as well as the on-line wall design, all require that vegetation is managed behind the structure in order to prevent future damage to the wall from invasive roots.

2.2 Summary of on-line wall design

This is shown on general arrangement drawing 60493385-C0478-DWG-0010, included in Appendix A. The wall would be constructed on the line of the existing 50 m long wall such that a stopping-up order is not required. This option would maintain the carriageway and footway at the current width and position. The wall would be a reinforced masonry cantilever wall with a reinforced concrete base slab – this was identified as the most economical option in the Feasibility Study and Options report. This has been developed to detailed design stage and a full set of construction drawings, bar-bending schedules, construction specification & works information was submitted to LBS on 24th May 2019. No utility diversions or works to the carriageway are required for construction of the on-line wall.

Prepared for: London Bourogh of Southwark CONWAYAECOM 60493385-C0478-REP-0003-A Offline Wall Options Report 5

C0478 Dulwich Upper Wood Retaining Wall Supplementary Feasibility Study & Options Report for an Off-line Wall

2.3 Off-Line Wall Option 1: Construct a new wall in front of the existing wall – raise the footway above existing wall

This option is shown on drawing 60493385-C0478-DWG-0005, included in Appendix B. A new wall would be built in-front of the existing at 600 mm minimum offset behind the existing kerb line. The existing wall would be buried in imported fill behind the new wall. The footway would be diverted behind the new wall, at a raised level. The new wall increases in height from south to north, as does the existing wall. A short increase in the length of the wall at the south end is necessary for the footway to ramp up onto the raised level above the existing wall. At the north end, however, the raised footway would be approximately 1.50m above the existing footway level and stairs and a ramp would be provided to the existing footway. The ramp is shown on the plan at 1:12, the absolute maximum gradient permissible by BD 29/17, in order to minimise the land take in the woodland and consequent loss of vegetation, including some mature trees. As shown, the ramps would occupy an area approximately 5.45 m x 11.5 m in the woodland, with a minimum additional 2.0 m around the permanent works for construction; a greater width may be required during construction due to the need to excavate into the earth bank. The size of this cannot be calculated without additional topographical information. Reducing the gradient of the ramps to the desirable maximum of 1:20 would lengthen the ramps and intrusion into the woodland be significant. The existing topographical information does not cover the area in which the proposed ramps would be located. Therefore, if this option were developed further, an additional topographical survey would be necessary. From this, the required excavation can be determined and the number of trees to be removed can be estimated. It is expected that the number of trees to be removed to allow construction of the ramps will be less than that required for construction of the on-line wall option. The new wall would be a reinforced masonry cavity wall. The previous feasibility study found this to be the most economical form of construction, with acceptable aesthetics. As the height of the wall is similar in this case, this remains the preferred option for the wall construction. This scheme would not affect the width of the carriageway and the proposed Quietway 7 scheme could be implemented without alteration. It is understood that no “stopping up” order would be required for this option. The stairs and ramps at the north end may disincentivise use of the footway. It is proposed that deterrent paving be placed along the verge to discourage walking along the verge. It is explicated that some pedestrians may walk along the cycleway when this is constructed in preference to using the stairs, creating a potential conflict between cyclists and pedestrians. This behaviour is difficult to disincentivise without negatively affecting legitimate use by cyclists. The existing lighting column adjacent to the wall opposite to the end of Jasper Road would have to be relocated, possibly behind the footpath. The existing utilities in the footway would have to be diverted – it is likely that the water main and the telecom cables would be accommodated within the verge in front of the wall and the street lighting power cables diverted below the new footway.

Prepared for: London Bourogh of Southwark CONWAYAECOM 60493385-C0478-REP-0003-A Offline Wall Options Report 6

C0478 Dulwich Upper Wood Retaining Wall Supplementary Feasibility Study & Options Report for an Off-line Wall

2.4 Off-line Wall Option 2: Construct a new wall in front of the existing wall with new footway – reduced carriageway

This option is shown on drawing 60493385-C0478-DWG-0006, included in Appendix B. Similar to off-line option 1 above, a new wall would be constructed in front of the existing wall, however, in this case the footway would be diverted in front of the new wall. This would result in a reduced width of Farquhar Road carriageway. A 6.0 m wide carriageway has been shown on the plan with a 2.0 m wide lightly-segregated cycleway and a 2.0 m wide kerbed footway. A wider carriageway could be accommodated if required, but the width of the cycleway or footway would have to be reduced. For example, a 7.30 m carriageway with a combined footway and cycleway width of 2.70 m over the length of the wall could also be possible. Some reconstruction of the carriageway would be necessary to position the crown along the new centreline of the road. Traffic disruption during construction will be greater if this option is implementing instead of the others. It is understood that a “stopping up” order would be required for implementation of this option. This presents a risk to the project if a judge declines to approve the order. It is expected that removal of trees would not be required for construction of this option. The fill between the existing wall and new wall would be sloped at 2 horizontally to 1 vertically. This allows for a shorter wall, and therefore lower construction costs, whilst ensuring the stability of the existing wall and embankment behind. The existing embankment would not be modified. At the south end, a gate and path would be provided into the woodland which would then connect with the existing woodland walkway behind the existing wall. The existing lighting column adjacent to the existing wall, opposite the junction with Jasper Road, would have to be relocated in the new footpath. New highway drainage gullies would be constructed along the new kerb line and connected to the existing drainage pipe. The existing utilities in the footway; water main, telecom and street lighting power cables, would be diverted below the new footway in front of the wall. It is noted that cars park along Farquhar Road on the west side. If this option is implemented, consideration may need to be given to imposing a parking restriction adjacent to the wall, due to the reduced width of carriageway.

2.5 Off-line Wall Option 3: Construct a new wall in front of the existing wall reducing the footway width.

This option would be similar to the solution proposed for the stabilisation of the Nunhead cemetery walls along Limesford Road. An L-shaped reinforced concrete wall would be constructed in front of the existing wall, with the toe constructed below the footpath. A brick facing would be constructed for aesthetic reasons. The utilities in the footway would have to be diverted. The width of the footway would be reduced by an estimated 500 mm. The loading on this wall would be more onerous than that on the Limesford Road walls due to the gradient of the ground behind the existing wall. Calculations have shown that at the south end, where the wall is at its highest, sufficient sliding resistance cannot be generated with a key below the toe of the wall. A line of bored piles would therefore be required to prevent sliding and the rig used for the piling would require a minimum of 8m headroom, as would the crane required to install the rebar cage. This would require removal of the tree

Prepared for: London Bourogh of Southwark CONWAYAECOM 60493385-C0478-REP-0003-A Offline Wall Options Report 7

C0478 Dulwich Upper Wood Retaining Wall Supplementary Feasibility Study & Options Report for an Off-line Wall canopy with a margin for safety which is considered not to be economical and would have a significant effect on the trees in Dulwich Upper Woodland. This option is therefore not recommended.

2.6 Option 4: Construct Gabion baskets in front of the existing wall

This option is similar to Option 2 but with Gabion baskets placed in front of the existing wall instead of constructing a reinforced masonry wall. As noted in the earlier options report, gabion baskets are not suitable for a structure with a 120-year design life and are prone to damage from either vandalism or theft of the rocks retained in the baskets. The aesthetics may not be suitable for the location. With all the above considerations in mind, this option is not recommended.

2.7 Option 5: Construct new wall in front of the existing wall, divert footway through Woodland.

This is similar to Option 2 above, but the footpath would be diverted through the woodland, rather than being constructed within the existing carriageway. The existing carriageway and proposed segregated cycleway would therefore be unaffected by the scheme. The new retraining wall would be constructed at a minimum 600 mm offset from the existing kerb line. It has been observed on site visits that the slope of the ground in the woodland would not be viable to construct a footpath off-line, compliant with current accessibility standards, without significant cut into the retained soil. This would inevitably result in the loss of a significant number of trees. Furthermore, the path would be remote from the carriageway and visibility of the footway would be obscured by the trees. Footway users may not perceive the footway as safe, particularly at night. The construction of such a path through the woodland would change the aesthetic character of the woodland significantly. For these reasons, this option is not recommended.

Prepared for: London Bourogh of Southwark CONWAYAECOM 60493385-C0478-REP-0003-A Offline Wall Options Report 8

C0478 Dulwich Upper Wood Retaining Wall Supplementary Feasibility Study & Options Report for an Off-line Wall

3. Conclusion & Recommendations

This report presents three technically feasible solutions to reconstruction of the wall, which is currently failing and in a dangerous condition: the on-line wall option developed previously and two possible off-line wall options. The relative advantages and disadvantages of the three options are summarised in the table below. It is recommended that these options are reviewed by LBS, in conjunction with the cost estimates to be provided separately, and a preferred solution identified.

On-line Wall Option Off-line Wall Option 1 Off-line Wall Option 2

Description Wall reconstructed on the Existing wall remains in Existing wall remains in line of the original. place, but a new off-line wall place, but a new off-line wall is constructed in front of the is constructed in front of the existing. Footway will be existing. Footway diverted to diverted onto top of the new front of new wall & wall with a new ramp and carriageway width will be stairs at north end of wall. reduced.

Future cycleway 2.0 m 2.0 m 2.0 m width

Carriageway width 7.0 m 8.0 m 6.0 m (After cycleway introduced)

“Stopping-up” of No. No. Yes. highway required?

Trees affected 34 to be removed To be confirmed if option None required for (estimated) progressed to detailed construction but vegetation design but estimated to be to be managed behind the less than 34 proposed wall to prevent on- going damage.

Existing wall Demolished Left in place and buried. Left in place and buried. Pilasters demolished. Pilasters demolished. Estimated costs for the above options are reported separately. The main on-going risks to the project are recorded in the Risk Register in Appendix C. Appendix A

Prepared for: London Bourogh of Southwark CONWAYAECOM 60493385-C0478-REP-0003-A Offline Wall Options Report 9

C0478 Dulwich Upper Wood Retaining Wall Supplementary Feasibility Study & Options Report for an Off-line Wall

Appendix A General Arrangement Drawing for On-line Wall

Prepared for: London Bourogh of Southwark CONWAYAECOM 60493385-C0478-REP-0003-A Offline Wall Options Report

NOTES

GENERAL 1. ALL DIMENSIONS IN MILLIMETRES UNLESS NOTED OTHERWISE. 171050 2. ALL LEVELS ARE IN METRES TO ORDNANCE DATUM NEWLYN. EXISTING TREES TOP BE FELLED N 171100 AS ENABLING WORKS PRIOR TO 3. DO NOT SCALE FROM THIS DRAWING. ! COMMENCEMENT OF THE WORKS.

TREE STUMPS AND ROOTS WILL 95.297 trunk 0.3 spread 8

ISO FULL BLEED A1 841 X 594 MM 4. THIS DRAWING IS BASED ON TOPOGRAPHICAL SURVEY UNDERTAKEN

EXIST WITHIN THE EXCAVATION. BY ABSOLUTE SURVEYS LTD DATED 01/11/2018. trunk 0.3 spread 8

95.343 533700 1300 533700 CONCRETE 94.787 94.095 95.200 trunk 0.3 spread 8 SOP 17 SOP 7 95.311 SOP 16 trunk 0.2 spread 6 5. CONCRETE FOR THE FOUNDATIONS AND THE COPING SHALL BE A 95.315 trunk 0.3 spread 8 EXISTING BRICK WALL TO BE 930 300 930 DESIGNED MIX IN ACCORDANCE WITH BS 8500 AND APPENDIX 17/1 OF DEMOLISHED OVER FULL 107.745 Canopy Height THE SPECIFICATION.

trunk 0.3 spread 8 WALL 13 WALL 14

LENGTH 94.487 trunk 0.3 spread 8

93.632 SOP 14 SOP 4

94.739 STEEL RAILING 94.476

1 IN 2 92.827 SOP 15 Approved: 93.541 94.351 BLINDING SHALL BE PRESCRIBED MIX ST2. 93.660 SOP 12 FALL FENCE 1000 SOP 11 SOP 21 PIPE BEDDING SHALL BE PRESCRIBED MIX ST2. ABOVE COPING. 300 SOP 6

96.566

FALL

2240 1 IN 2 IN 1 94.835

93.302 SOP 13 WALL 1 93.313 6. EXPOSED ARISES ON COPING SHALL BE FORMED TO A 10mm. RADIUS.

92.403 trunk 0.3 spread 8 92.545 92.766 93.501 93.014 93.266 93.404

TOW

93.421 93.892

91.786 93.570 94.765

92.880 93.030 93.019 93.175 93.174 trunk 0.2 spread 6

94.377 92.304

92.569 92.715 92.729 92.876 TOW 93.578

92.555 93.993

93.374 92.383 TOW 92.408

93.851

trunk 0.3 spread 8 94.230 93.845

91.857 92.085 94.250 91.672 93.835

93.992

91.395 TOW SOP 20

94.887 7. ALL BURIED BRICK AND CONCRETE SURFACES GREATER THAN 93.982

94.141

91.099 92.730

90.785 94.439

94.143

trunk 0.6 spread 8 94.712

94.545 94.203

94.807

iron fence 92.952

93.105

94.796

94.525

WALL 2 WALL 3 WALL 4 WALL 5 WALL 6 93.327 100mm BELOW FINISHED GROUND LEVEL SHALL BE PAINTED WITH

94.528 94.811

94.811

93.640 WALL 7 94.952

1677

94.943 SOP 2 93.845

94.820 SOP 19 TWO COATS OF A BELOW GROUND BITUMINOUS EMULSION 95.495

92.065 WALL 8 92.307

SOP 1 94.020

94.914 92.267 trunk 0.3 spread 8 SOP 9 94.259 92.636

91.350 WALL 9 92.899 91.826

91.611

92.139 WATERPROOFING. SEALING WITH PRIMER IS REQUIRED FOR ALL

90.837

91.001 WALL 10 94.379

SOP 8 fence iron 93.029 94.625 IC WTR 92.466 WALL 11

93.233 WALL 12 SURFACES TO RECEIVE TAR OR BITUMEN WATERPROOFING PRIOR TO IC BT 92.369 93.551 Lp 94.231 93.755 IC WTR APPLICATION. 93.968

SOP 3 94.224 SOP 5 94.338

TOK 92.000 94.608 90.853 91.598 92.401 SOP 10 SOP 18

TOK 300

capping stone 92.837 broken brick wall 91.465 BOK 91.870 92.268 TOK 93.295 8. CONCRETE FINISHES ARE TO SPECIFICATION CLAUSE 1708 AND ARE

90.977 BOK

6N/6P FILL WITH 150 TOPSOIL 92.714 93.711 NEW STEEL FENCE PANEL

BOK 93.147 2300 *

94.048 INDICATED THUS:

TO BE DRESSED AROUND NOTE PRESENCE OF UTILITIES IN FOOTWAY: 93.637

TOK 1400 LONG IN POST-IN-HOLE 94.490

94.021 F_ CLASS OF FORMED FINISH

Checked: BOK

RETURN WALL AT MAX. SLOPE EXISTING STEEL RAILING UK POWER NETWORKS MASS CONCRETE STAIRS. 94.368 FOUNDATION TO LINE UP gul 93.823 U_ CLASS OF UNFORMED FINISH 1 IN 2. FENCE TO BE REINSTATED ! BT OPENREACH FOR DETAILS SEE WITH EXISTING FENCE. AT COMPLETION OF WORKS. THAMES WATER DRG. No. -0011. CONTRACTOR SHALL LOCATE AND MASONRY MARK THE UTILITIES ON SITE AND PROVIDE PROTECTION TO PLANT 9. BRICKS IN THE REPLACEMENT WALLS SHALL BE BLUE HD TYPE TO BE AGREED WITH OWNERS. B CLAY ENGINEERING BRICKS CONFORMING TO BS EN 771-1 AND APPENDIX 24/1 OF THE SPECIFICATION. PLAN VIEW DIMENSION * BETWEEN FACES OF BRICK WALLS. Scale 1:100 @ A1 10. STRETCHER BOND SHALL BE USED THROUGHOUT.

11. MORTAR SHALL BE DESIGNATION (i) IN ACCORDANCE WITH TABLE 24/1 OF THE SPECIFICATION. JOINTS SHALL BE 10mm WIDE. C C C C C C C C C C L L L L L L L L L L 12. ALL JOINTING SHALL BE FLUSH OR BUCKET-HANDLE.

Designer: JOINT JOINT JOINT JOINT JOINT JOINT JOINT JOINT JOINT JOINT MASS CONCRETE STAIRS 4045 4725 4725 4725 4725 4725 4725 4725 4725 4725 1570 2300 * 13. CAVITY INFILL CONCRETE SHALL BE A DESIGNED MIX IN 300 GOING /150 RISE. ACCORDANCE WITH SPECIFICATION APPENDIX 25/3. 2000 STEEL RAILING PRECAST CONCRETE 330 THK. REINFORCED CLEAR NEW STEEL FENCE 14. CONSTRUCTION OF THE GROUTED-CAVITY WALLS SHALL BE IN FENCE 1000 COPING. MASONRY CAVITY WALL. PANEL 1400 LONG ACCORDANCE WITH CLAUSE 2503 AND APPENDIX 25/3 OF THE A ABOVE COPING. 94.905m IN POST-IN-HOLE SPECIFICATION. 0010 FOUNDATION TO LINE 6N/6P FILL WITH 150 TOPSOIL UP WITH EXISTING TO BE DRESSED AROUND 93.925m 15. WALL TIES BETWEEN THE LEAVES OF BRICKWORK SHALL BE 6mm. 93.700m FENCE. RETURN WALL AT MAX. SLOPE LINK BARS AS SHOWN IN DETAIL 3 ON 1 IN 2. DRAWING No.60493385-C0478-DWG-0011, FORMED OF STAINLESS STEEL DESIGNATION 1.4429 TO BS EN 10088. WALL TIES SHALL BE 92.655m ! PLACED AT MAXIMUM 450mm. CENTRES HORIZONTALLY AND MAXIMUM 600mm. CENTRES VERTICALLY. WALL TIES SHALL BE PLACED AT 300mm. CENTRES VERTICALLY WITHIN 200mm. OF THE MOVEMENT STEPPED REINFORCED JOINTS ON EARTH SIDE. 90.700m CONCRETE FOUNDATION. 75 THK. BLINDING. 16. WALL INFILL CONCRETE SHALL NOT BE PLACED UNTIL THE MORTAR AT THE TOP OF THE WALL HAS ATTAINED A MINIMUM OF 60% OF THE SPECIFIED 28 DAY CHARACTERISTIC STRENGTH.

17. HIGH BOND DAMP PROOF MEMBRANE BELOW COPING SHALL COMPLY WITH THE REQUIREMENTS OF SPECIFICATION APPENDIX 25/3. Project Management Initials: DEVELOPED ELEVATION ALONG WALL STEEL RAILING FENCE. Scale 1:100 @ A1 18. STEEL RAILING FENCE TO BE IN ACCORDANCE WITH SPECIFICATION APPENDIX 3/1. CL CL STEEL RAILING FENCE JOINT JOINT TO BS 1722-9 1000 HIGH ABOVE WALL 4725 HEALTH AND SAFETY, WELFARE OR ENVIRONMENTAL CORED AND GROUTED HAZARD - SEE HAZARD REGISTER IN PRE-CONSTRUCTION MIN 400 INTO WALL ! INFORMATION PACK DOCUMENT 60493385-C0478-PC1-001. PRECAST CONCRETE 1000 COPING 430 WIDE STEEL RAILING x MIN 125 THK./MAX 145 FENCE 1000 ABOVE THK. WITH HIGH BOND DPC COPING. BELOW COPING. SEE SETTING OUT POINTS (m) DETAIL 1 ON DRG. No.-0011. SOP EASTING NORTHING 1 533695.711 171107.478 1 2 533695.887 171089.259 75 3 (MIN) 3 533694.506 171059.371 PRECAST CONCRETE 4 533696.182 171059.294 75 1000 ! COPING SEGMENTS 5 533694.400 171057.073 1190 LONG WITH 330 THK. REINFORCED REINFORCED MASONRY 6N / 6P BACKFILL 6 533696.076 171056.996 10 THK. MORTAR MASONRY CAVITY WALL. CAVITY WALL 330 THK

7 533697.951 171107.500 JOINTS. 225 BITUMINOUS BELOW GROUND 8 533695.408 171107.775 WATERPROOFING, SEE NOTE 7. 9 533695.587 171089.265 225 C 23/05/19 FOR CONSTRUCTION DT RAJ SRM DRAINAGE LAYER TO 10 533694.193 171059.085 B 09/05/19 FOR APPROVAL DSF RAJ SRM CLAUSE 513 11 533696.468 171058.980 A 08/03/19 APPROVAL IN PRINCIPLE VF RAJ DP 12 533696.511 171059.909 FOR DETAIL OF JOINT SEE DRN CHKD APRVD REV DATE REVISION DESCRIPTION / DETAILS 13 533695.534 171059.954 DETAIL 2 ON DRG. No. -0011. BY BY BY EXISTING GROUND LINE. 14 533696.887 171089.241 10 FOOTPATH TO BE 300 150 DIA PORUS PIPE LAID REINSTATED TO 15 533696.721 171106.488 JOINT TYP TO 1:100 MIN FALL ON MATCH EXISTING 16 533698.260 171106.503 CONCRETE BEDDING 10 17 533698.248 171107.803 JOINT U1

18 533694.115 171057.387 100 19 533694.072 171056.458 MINIMUM EXTENT OF 160 TOOLEY STREET LONDON SE1P 5LX 20 533696.347 171056.353 300 6N/6P BACKFILL 21 533696.390 171057.282 F1 F1

250 (60° MAX) CJ PROJECT: 300 250 300 C0478 DULWICH UPPER WOOD CJ

300 RETAINING WALLS 250 75 THK. BLINDING 75 THK. BLINDING. 250 250 1300 500 TITLE:

250 250 STEPPED REINFORCED CONCRETE FOUNDATION. GENERAL ARRANGEMENT SHEET 1

SECTION A-A CONTRACT NO: DRAWN VF 60493385-C0478 DESIGNED NR Scale 1:20@ A1 TYPICAL PART ELEVATION ON WALL SCALE: PURPOSE: CHECKED RAJ Scale 1:25 @ A1 AS SHOWN @ A1 FOR CONSTRUCTION 1m 0 1 2 3 4 5m APPROVED DP DRAWING NO: REV: 60493385-C0478-DWG-0010 C Scale 1:100 @ A1 DATE DRAWN: DATE ISSUED: MARCH 2019 MARCH 2019 F:\PROJECTS\TRAFFIC - SOUTHWARK HAPS 201415\06. LOT C PROFESSIONAL SERVICES\PROJECTS\C0478 DULWICH WOOD RW\09 CAD\SHEETS\60493385-C0478-DWG-0010 & 0011.DWG

BASED UPON THE ORDNANCE SURVEY 1:1250 MAPPING WITH THE PERMISSION OF THE CONTROLLER OF HER MAJESTY'S STATIONARY OFFICE © CROWN COPYRIGHT 2018. UNAUTHORISED REPRODUCTION AND ANY CROWN COPYRIGHT INFRINGES MAY LEAD TO PROSECUTION OR CIVIL PROCEEDINGS. ON BEHALF OF LONDON BOROUGH OF SOUTHWARK. LICENCE NO. 0100019252. C0478 Dulwich Upper Wood Retaining Wall Supplementary Feasibility Study & Options Report for an Off-line Wall

Appendix B Drawings for Offline Wall Options 1 & 2

Prepared for: London Bourogh of Southwark CONWAYAECOM 60493385-C0478-REP-0003-A Offline Wall Options Report

C0478 Dulwich Upper Wood Retaining Wall Supplementary Feasibility Study & Options Report for an Off-line Wall

Appendix C Risk Register

Prepared for: London Bourogh of Southwark CONWAYAECOM 60493385-C0478-REP-0003-A Offline Wall Options Report

C0478 Dulwich Upper Wood Retaining Wall Supplementary Feasibility Study & Options Report for an Off-line Wall

No Risk Probability Impact Mitigation Action By 1 Stopping up order not Medium High Option 1 or on-line wall option do not carry this risk. LBS granted (Off-line wall option 2 only)

2 On-going damage to Medium High LBS to devise and implement management plan for LBS replacement wall from vegetation in zone behind replacement wall. trees

Prepared for: London Bourogh of Southwark CONWAYAECOM