Tfl land holdings drainage strategy & flood risk assessment addendum by Catherine Makegood

TfL Landholdings at Northwood Drainage Strategy & Flood Risk Assessment Addendum 034233 4 March 2016 Revision 00

Revision

Description

Issued by

Date

Checked

Submission to LBH

EAF

04/03/2016

DKP

O:\034233 Green Lane, Northwood Station Phase 2\F34 Water\03 Reports\Post_Submission_Design_Note\160303 EF 034233 Drainage Strategy & Flood Risk Assessment Addendum 00.docx This report has been prepared for the sole benefit, use and information of TfL for the purposes set out in the report or instructions commissioning it. The liability of Buro Happold Limited in respect of the information contained in the report will not extend to any third party. author

Edward Funnell

date

04/03/2016

approved

David Palmer

David Palmer I am approving this document 2016.03.04 15:45:38Z00'00'

signature

date

04/03/2016

Revision 00 4 March 2016 Page 3

Contents 1 Introduction

Appendix A Appendix B Appendix C Appendix D Appendix E Appendix F Appendix G Appendix H

Revision 00 4 March 2016 Page 5

Introduction

A planning application for the development of the TfL Landholdings at Northwood site (71083/APP/2015/4037) was th

submitted to the London Borough of Hillingdon (LBH) on the 28 of October 2015. This submission included a Flood Risk Assessment (FRA) and Drainage Strategy prepared by BuroHappold (BH). Following this submission, LBH requested that additional information be provided to support the application. Following a meeting with LBH, a list of requested information was confirmed with LBH in an email dated 23/02/2016. The list of requested information items consists of the following: 1. 2. 3. 4. 5.

Provide validation of the catchments shown in the planning application against the Thames Water (TW) drainage network. Provide details of the overland surface water run-off contributing to Station Approach. Produce a plan showing the expected direction of overland flow in the event that the drainage system proposed on Green Lane is exceeded. Produce an indicative plan showing the expected drainage direction of overland flow along Central Way, including the area around the carpark entrance. Send LBH the dimensions, total length, buried length, maintenance records and details of the planned maintenance, monitoring and repair work for the existing culvert to the south of the site. Planned maintenance, monitoring and repair works should be proposed with consideration of the impact that a blockage of this culvert would have to the proposed, more vulnerable users which will be located adjacent to the culvert. Produce a plan showing the phasing of the development and required enabling works for each phase. Enabling works should include the installation of the required utilities proposed on Central Way. On these plans show for each phase:  direction of proposed drainage;  the location of drainage outflow connections; and  the peak capacity/outflow from these connections. Provide commentary on the outflow from the proposed oversized pipes to the existing culvert at the south of the site. In this commentary provide a comparison of the pipe diameters of the outlet from the oversized pipes and the existing culvert at the south of the site. Demonstrate that opportunities to utilise sustainable urban drainage within the development have been explored. Where the development does not utilise the most sustainable drainage solution provide justification for this.

A series of Technical Notes have been prepared to provide the information requested by LBH for the eight items above. Technical Notes included in Appendix A – H respectively address items 1 to 8 listed above.

Revision 00 4 March 2016 Page 7

Appendix A

Revision 00 4 March 2016 Page 8

Design Note 

Pro ject

Subject Project no Date

TfL Landholdings at Northwood Response to LBH Queries, Item 1 of 8 034233 3 March 2016 Revision

Description

Issued by

Date

Response to LBH Query 1 of 8

EAF

03/03/2016

Introduction

Approved (signature) David Palmer I am approving this document 2016.03.04 15:53:34Z00'00'

A planning application for the development of the TfL Landholdings at Northwood site (71083/APP/2015/4037) was th submitted to the London Borough of Hillingdon (LBH) on the 28 of October 2015. This submission included a Flood Risk Assessment (FRA) and Drainage Strategy prepared by BuroHappold (BH). Following this submission, LBH requested that additional information be provided to support the application. Following a meeting with LBH, a list of requested information was confirmed with LBH in an email dated 23/02/2016. The list of requested information items consists of the following: 1. 2. 3. 4. 5.

This Technical Note provides the information requested by LBH for item 1 of the above.

This report has been prepared for the sole benefit, use and information of [Client] for the purposes set out in the Design note or instructions commissioning it. The liability of BuroHappold Engineering in respect of the information contained in the report will not extend to any third party. All concepts and proposals are copyright © March 2016. Issued in commercial confidence.

Validation of BH Catchments & TW Drainage Networks

The BH Drainage Strategy shows that there are two catchments that contribute flows to the Station Approach area of the proposed development. The extent of these catchments was identified using the Environment Agency’s 1m LiDAR data and GRASS software in GIS and are shown in Figure 2—1.

Figure 2—1: Plan showing external catchment areas contributing to the proposed levelled plaza area in place of Station Approach

TW provided details of the drainage assets and plans TQ0991NW and TQ0991SW were geo-referenced into GIS and the BH catchments superimposed on the TW plans to show how they relate to each other. A copy of the non-georeferenced asset plans as supplied by TW are included in Appendix A: TW Asset Plans for additional comparison. Figure 2—2 shows how the TW drainage is situated with the catchments identified by BH. The BH catchments have been derived from the EA 1m Lidar data and the edges of each catchment represent the high point between adjacent catchments. The plan shows the high point in the TW drainage run, indicated by a yellow circle. It can be seen that the high spot of each drainage run is within the BH catchment and therefore it is concluded that the BH catchments accurately reflect the TW drainage network. It should be further noted that, as the plan shows, the BH catchment extends some way beyond the indicated high point of the TW drainage sewers and it can be assumed that there is an acceptable degree of resilience in the catchment delineation carried out by BH. It is concluded that the asset plans provided by TW support the catchments plans shown in the BH Drainage Strategy.

Page 2 of 6

Figure 2â&#x20AC;&#x201D;2: Plan showing external catchments overlaid on the TW Drainage Network

Page 3 of 6

Design Note 3

Appendix A: TW Asset Plans

Page 5 of 6

Page 6 of 6

Appendix B

Revision 00 4 March 2016 Page 9

Technical Note Project

TfL Landholdings at Northwood

Subject

Response to LBH Queries, Item 2 of 8

Project no Date

034233 29 February 2016 Revision

Description

Issued by

Date

Response to LBH Query 2 of 8

29/02/2016

Approved (signature)

Introduction

This Technical Note provides the information requested by LBH for item 2 of the above.

Details of the Overland Surface Water Run-off Contributing to Station Approach

The overland surface water runoff contributing to the Station Approach is illustrated in the BH Drainage Strategy report and the catchment areas are identified using the Environment Agency’s 1m LiDAR data and GRASS software in GIS, shown in Figure 2-1

Figure 2—1: Plan showing external catchment areas contributing to the proposed levelled plaza area in place of Station Approach

Catchment area 1 = 0.933 ha and catchment area 2 = 0.140ha No detail survey data is available for catchment area above, therefore, the catchment area contributing to the Station Approach is then assessed based on the plan in Figure 2-1:  

the fraction of pervious area within catchment 1 is as per the tree canopy; and the assumption that only a portion of the runoff from Eastbury Road (Catchment 1) would flow across the intersection of Green Lane to Station Approach, with the remaining portion flowing west (downhill) along the Green Lane.

Based on the above it has been assumed that 50% of the runoff from catchment 1 and 100% of the runoff from catchment 2 would report to Station Approach. The existing sewers within Catchment 1 and 2 are assumed to have been designed to convey storm events up to and including the 1 in 30 year, without climate change event with no flooding. The runoff from Catchment 1 and 2 has been modelled in the MicroDrainage design suite for a number of storm events as follows:   

1 in 2 year; 1 in 30 year; and 1 in 100 year + 30% climate change. Page 2 of 5

In order to intercept the surface water flow safely from the 2 catchment areas a new kerb is proposed to be installed on the southern side of Green Lane. Refer to Appendix A for the overland runoff from these 2 catchment areas. As part of the diversion proposal the existing sewers along Green Lane are proposed to be diverted by installing a new surface water drainage system and connecting to a new drainage system in Central Way. At the southern end of the new Central Way surface water sewer, i.e. within the new townhouses, oversized pipes are introduced to attenuate the runoff to the same level that would have been experience from the site in its current stated. The flow from the oversized pipe will enter the existing culvert to the south of the development and the flow will not exceed the existing rate of runoff. The calculations indicated the surface water runoff from these 2 catchment area, i.e. area 1 and area 2, can be captured safely, i.e. no flooding on Green Lane and Central Way or any part of the site, within the proposed surface water drainage system for up to 1 in 100 year storm event + 30% climate change. Refer to Appendix B for the MicroDrainageâ&#x20AC;&#x2122;s output.

Page 3 of 5

Technical Note Appendix A: Overland Runoff for Phase 1 Surface Water Flow Based on Different Storm Events for Phase 1

+77.200m +77,200mm AOD

+77.321m +77,321mm AOD

A linear drain (as a cut drain) is proposed at the entrance/exit of the basement car parking. The road level is proposed to fall away from this entrance to prevent the surface water runoff to the basement entrance.

CUT OFF DRAIN

+77.196m +77,196mm AOD

+77,350mm AOD

BEANY KERB

+78.329m +78,329mm AOD

+77,350mm AOD

LINE INDICATES ROUTE THROUGH CAR PARK BELOW

+72.100m +72,100mm AOD

RG +72,300mm AOD

+74.050m

+76.850m +76,850mm AOD

+74,050mm AOD

+78.500m +78,500mm AOD

+72.000m

CUT OFF DRAIN

+78.864m +78,864mm AOD

ROAD GULLY

Overland runoff within this area, hatched in blue, will be captured by a linear drain as cut-off drain at the bottom of the Central Way and road gully at the sides of the road. JOB TITLE:

TfL Landholdings at Northwood

SKETCH TITLE: Overland Runoff for Phase 1

Overland runoff within this area, hatched in yellow, will be captured by the new beany kerb and existing road gullies at the edge of Green Lane .

ROAD GULLY

JOB NUMBER:

034233

DATE:

29/02/2016

SKETCH NUMBER:

SKETCH 001

INITIALS:

+72,000mm AOD

SURFACE WATER FLOW BASED ON CATCHMENT AREA 1 & 2 AND PHASE 1 DEVELOPMENT Q2 = 97.7 L/s Q5= 121.0 L/s Q10= 210.7 L/s Q30= 265.6 L/s Q100= 280.3 L/s

SURFACE WATER FLOW BASED ON CATCHMENT AREA 1 AND 2 Q2 = 85.3 L/s Q5= 107.1 L/s Q10= 189.6 L/s Q30= 240.3 L/s Q100= 296.1 L/s CAPACITY OF A 375 DIAMETER PIPE AT 1:300 IS ESTIMATED TO BE 115L/s. WHEN THE SURFACE WATER FLOW EXCEED THE PIPE CAPACITY THE MICRODRAINAGE OUTPUT DOES NOT INDICATE THERE IS FLOODING BUT SURFCHARGED WITHIN THE DRAINAGE SYSTEM ALONG GREEN LANE. THIS IS DUE TO THE FLOW IS CONTINUOUS WITHIN THE DRAINAGE NETWORK SYSTEM AND THE FLOW IS BELOW THE HYDRAULIC GRADE LINE. JOB TITLE:

TfL Landholdings at Northwood

SKETCH TITLE: Surface Water Flow Based on Different Storm Events for Phase 1

JOB NUMBER:

034233

DATE:

29/02/2016

SKETCH NUMBER:

SKETCH 002

INITIALS:

CAPACITY OF A 900 DIAMETER PIPE AT 1:180 IS ESTIMATED TO BE 1484.2L/s

Appendix B: MicroDrainage Output

Page 5 of 5

Buro Happold Camden Mill Lower Bristol Road Bath BA2 3DQ Date 23.09.2015 File 160223 HIGHWAY DRAIN... Micro Drainage

Page 1 034233 Green Lane Northwood Station Phase 2 Highway Drainage System Designed by NP Checked by GL Network 2013.1 Time Area Diagram for Storm

Time Area (mins) (ha)

0-4 0.194

4-8 0.403

8-12 0.080

Time (mins)

Area (ha)

12-16 0.029

Total Area Contributing (ha) = 0.707 Total Pipe Volume (m³) = 139.760

Buro Happold Camden Mill Lower Bristol Road Bath BA2 3DQ Date 23.09.2015 File 160223 HIGHWAY DRAIN... Micro Drainage BASED ON 50% OF CATCHMENT AREA 1 AND 100% OF CATCHMENT AREA 2 CATCHMENT AREA 1 = 0.933 HA CATCHMENT AREA 2 = 0.140 HA

Page 2 034233 Green Lane Northwood Station Phase 2 Highway Drainage System Designed by NP Checked by GL Network 2013.1

Existing Network Details for Storm PN

P1.000 P1.001 P1.002 P1.003 P1.004 P1.005 P1.006 P1.007 P1.008 P1.009 P1.010 P1.011

Length Fall Slope I.Area T.E. Base k HYD DIA (m) (m) (1:X) (ha) (mins) Flow (l/s) (mm) SECT (mm) 21.892 35.312 12.299 34.072 33.958 22.753 20.752 33.821 42.172 53.856 54.782 4.470

0.073 0.118 0.041 0.681 1.698 1.896 0.138 0.188 0.211 0.269 0.274 0.022

299.9 299.3 300.0 50.0 20.0 12.0 150.4 179.9 199.9 200.2 199.9 200.0

0.200 0.200 0.207 0.000 0.000 0.000 0.050 0.000 0.000 0.000 0.050 0.000

10.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

0.0 0.0 0.0 0.0 0.0 0.0 5.0 1.0 0.0 0.0 3.0 0.0

0.600 0.600 0.600 0.600 0.600 0.600 0.600 0.600 0.600 0.600 0.600 0.600

Network Results Table PN

P1.000 P1.001 P1.002 P1.003 P1.004 P1.005 P1.006 P1.007 P1.008 P1.009 P1.010 P1.011

US/IL Σ I.Area Σ Base Vel Cap (m) (ha) Flow (l/s) (m/s) (l/s) 74.825 74.752 74.634 74.593 73.912 72.214 69.568 69.430 69.242 69.031 68.762 68.488

0.200 0.400 0.607 0.607 0.607 0.607 0.657 0.657 0.657 0.657 0.707 0.707

0.0 0.0 0.0 0.0 0.0 0.0 5.0 6.0 6.0 6.0 9.0 9.0

1.04 1.04 1.04 2.57 4.07 5.25 2.55 2.33 2.43 2.43 1.11 1.11

115.0 115.1 115.0 283.5 449.3 580.4 1624.1 1484.2 2107.7 2105.9 78.3 78.3

o 375 o 375 o 375 o 375 o 375 o 375 o 900 o 900 o 1050 o 1050 o 300 o 300

NEW PIPEs

OVERSIZED PIPE

Buro Happold Camden Mill Lower Bristol Road Bath BA2 3DQ Date 23.09.2015 File 160223 HIGHWAY DRAIN... Micro Drainage

Page 3 034233 Green Lane Northwood Station Phase 2 Highway Drainage System Designed by NP Checked by GL Network 2013.1 Manhole Schedules for Storm

MH Name

MH MH CL (m) Depth (m)

MH Connection

MH Diam.,L*W (mm)

Pipe Out Invert Diameter Level (m) (mm)

Pipes In Invert Diameter Backdrop Level (m) (mm) (mm)

MH1 77.200 2.375 Open Manhole

1500 P1.000

74.825

375

MH2 77.477 2.725 Open Manhole

1500 P1.001

74.752

375 P1.000

74.752

375

MH3 78.800 4.166 Open Manhole

1500 P1.002

74.634

375 P1.001

74.634

375

MH4 78.700 4.107 Open Manhole

1500 P1.003

74.593

375 P1.002

74.593

375

MH5 75.900 1.988 Open Manhole

1500 P1.004

73.912

375 P1.003

73.912

375

MH6 74.210 1.996 Open Manhole

1500 P1.005

72.214

375 P1.004

72.214

375

MH7 72.398 2.830 Open Manhole

2100 P1.006

69.568

900 P1.005

70.318

375

MH8 72.000 2.570 Open Manhole

2100 P1.007

69.430

900 P1.006

69.430

900

MH9 71.600 2.358 Open Manhole

2100 P1.008

69.242

1050 P1.007

69.242

900

MH10 71.600 2.569 Open Manhole

2100 P1.009

69.031

1050 P1.008

69.031

1050

MH11 71.600 2.838 Open Manhole

1200 P1.010

68.762

300 P1.009

68.762

1050

MH12 71.390 2.902 Open Manhole

1200 P1.011

68.488

300 P1.010

68.488

300

OUTFALL

P1.011

68.466

300

MHEXT 71.577 3.111 Open Manhole

1500

ÂŠ1982-2012 Micro Drainage Ltd

225

Buro Happold Camden Mill Lower Bristol Road Bath BA2 3DQ Date 23.09.2015 File 160223 HIGHWAY DRAIN... Micro Drainage

Page 4 034233 Green Lane Northwood Station Phase 2 Highway Drainage System Designed by NP Checked by GL Network 2013.1 PIPELINE SCHEDULES for Storm Upstream Manhole

Hyd Diam MH C.Level I.Level D.Depth Sect (mm) Name (m) (m) (m)

P1.000 P1.001 P1.002 P1.003 P1.004 P1.005 P1.006 P1.007 P1.008 P1.009 P1.010 P1.011

o 375 MH1 o 375 MH2 o 375 MH3 o 375 MH4 o 375 MH5 o 375 MH6 o 900 MH7 o 900 MH8 o 1050 MH9 o 1050 MH10 o 300 MH11 o 300 MH12

77.200 77.477 78.800 78.700 75.900 74.210 72.398 72.000 71.600 71.600 71.600 71.390

74.825 74.752 74.634 74.593 73.912 72.214 69.568 69.430 69.242 69.031 68.762 68.488

2.000 2.350 3.791 3.732 1.613 1.621 1.930 1.670 1.308 1.519 2.538 2.602

MH Connection Open Open Open Open Open Open Open Open Open Open Open Open

MH DIAM., L*W (mm)

Manhole Manhole Manhole Manhole Manhole Manhole Manhole Manhole Manhole Manhole Manhole Manhole

1500 1500 1500 1500 1500 1500 2100 2100 2100 2100 1200 1200

Downstream Manhole PN

P1.000 P1.001 P1.002 P1.003 P1.004 P1.005 P1.006 P1.007 P1.008 P1.009 P1.010 P1.011

Length Slope MH C.Level I.Level D.Depth (m) (1:X) Name (m) (m) (m) 21.892 35.312 12.299 34.072 33.958 22.753 20.752 33.821 42.172 53.856 54.782 4.470

299.9 MH2 299.3 MH3 300.0 MH4 50.0 MH5 20.0 MH6 12.0 MH7 150.4 MH8 179.9 MH9 199.9 MH10 200.2 MH11 199.9 MH12 200.0 MHEXT

77.477 78.800 78.700 75.900 74.210 72.398 72.000 71.600 71.600 71.600 71.390 71.577

74.752 74.634 74.593 73.912 72.214 70.318 69.430 69.242 69.031 68.762 68.488 68.466

2.350 3.791 3.732 1.613 1.621 1.705 1.670 1.458 1.519 1.788 2.602 2.811

MH Connection Open Open Open Open Open Open Open Open Open Open Open Open

ÂŠ1982-2012 Micro Drainage Ltd

Manhole Manhole Manhole Manhole Manhole Manhole Manhole Manhole Manhole Manhole Manhole Manhole

MH DIAM., L*W (mm) 1500 1500 1500 1500 1500 2100 2100 2100 2100 1200 1200 1500

Buro Happold Camden Mill Lower Bristol Road Bath BA2 3DQ Date 23.09.2015 File 160223 HIGHWAY DRAIN... Micro Drainage

Page 5 034233 Green Lane Northwood Station Phase 2 Highway Drainage System Designed by NP Checked by GL Network 2013.1

Setting Out Information - True Coordinates (Storm) PN

USMH Dia/Len Width US Easting US Northing Layout Name (mm) (mm) (m) (m) (North)

P1.000

MH1

1500

509235.799

191467.217

P1.001

MH2

1500

509256.507

191460.117

P1.002

MH3

1500

509291.268

191453.904

P1.003

MH4

1500

509292.008

191441.627

P1.004

MH5

1500

509297.878

191408.065

P1.005

MH6

1500

509305.634

191375.005

P1.006

MH7

2100

509311.413

191352.998

P1.007

MH8

2100

509317.623

191333.197

P1.008

MH9

2100

509326.423

191300.541

P1.009 MH10

2100

509339.677

191260.505

P1.010 MH11

1200

509357.536

191209.696

P1.011 MH12

1200

509375.425

191157.917

DSMH Dia/Len Width DS Easting DS Northing Layout Name (mm) (mm) (m) (m) (North)

P1.011 MHEXT

1500

509378.675

191154.849

ÂŠ1982-2012 Micro Drainage Ltd

Buro Happold Camden Mill Lower Bristol Road Bath BA2 3DQ Date 23.09.2015 File 160223 HIGHWAY DRAIN... Micro Drainage

Page 6 034233 Green Lane Northwood Station Phase 2 Highway Drainage System Designed by NP Checked by GL Network 2013.1 Area Summary for Storm

Pipe PIMP PIMP PIMP Gross Imp. Pipe Total Number Type Name (%) Area (ha) Area (ha) (ha) 1.000 1.001 1.002 1.003 1.004 1.005 1.006 1.007 1.008 1.009 1.010 1.011

100 100 100 100 100 100 100 100 100 100 100 100

0.200 0.200 0.207 0.000 0.000 0.000 0.050 0.000 0.000 0.000 0.050 0.000 Total 0.707

Free Flowing Outfall Details for Storm Outfall Outfall C. Level I. Level Min D,L W Pipe Number Name (m) (m) I. Level (mm) (mm) (m) P1.011

MHEXT

71.577

68.466

69.500 1500

Simulation Criteria for Storm Volumetric Runoff Coeff Areal Reduction Factor Hot Start (mins) Hot Start Level (mm) Manhole Headloss Coeff (Global) Foul Sewage per hectare (l/s)

0.750 Additional Flow - % of Total Flow 1.000 MADD Factor * 10m³/ha Storage 0 Inlet Coeffiecient 0 Flow per Person per Day (l/per/day) 0.500 Run Time (mins) 0.000 Output Interval (mins)

0.000 2.000 0.800 0.000 60 1

Number of Input Hydrographs 0 Number of Offline Controls 0 Number of Time/Area Diagrams 0 Number of Online Controls 0 Number of Storage Structures 0 Number of Real Time Controls 0

Synthetic Rainfall Details Rainfall Model FSR Profile Type Summer Return Period (years) 2 Cv (Summer) 0.750 Region England and Wales Cv (Winter) 0.840 M5-60 (mm) 20.800 Storm Duration (mins) 30 Ratio R 0.438

Buro Happold Camden Mill Lower Bristol Road Bath BA2 3DQ Date 23.09.2015 File 160223 HIGHWAY DRAIN... Micro Drainage

Page 7 034233 Green Lane Northwood Station Phase 2 Highway Drainage System Designed by NP Checked by GL Network 2013.1

2 year Return Period Summary of Critical Results by Maximum Level (Rank 1) for Storm

Simulation Criteria Areal Reduction Factor 1.000 Additional Flow - % of Total Flow Hot Start (mins) 0 MADD Factor * 10m³/ha Storage Hot Start Level (mm) 0 Inlet Coeffiecient Manhole Headloss Coeff (Global) 0.500 Flow per Person per Day (l/per/day) Foul Sewage per hectare (l/s) 0.000

0.000 2.000 0.800 0.000

Number of Input Hydrographs 0 Number of Offline Controls 0 Number of Time/Area Diagrams 0 Number of Online Controls 0 Number of Storage Structures 0 Number of Real Time Controls 0 Synthetic Rainfall Details Rainfall Model FSR M5-60 (mm) 20.800 Cv (Summer) 0.750 Region England and Wales Ratio R 0.438 Cv (Winter) 0.840 Margin for Flood Risk Warning (mm) 300.0 DVD Status OFF Analysis Timestep Fine Inertia Status OFF DTS Status ON

Profile(s) Duration(s) (mins)

Summer and Winter 15, 30, 60, 120, 180, 240, 360, 480, 600, 720, 960, 1440 2, 5, 10, 30, 100 0, 0, 30, 30, 30

Return Period(s) (years) Climate Change (%)

PN P1.000 P1.001 P1.002 P1.003 P1.004 P1.005 P1.006 P1.007 P1.008 P1.009 P1.010 P1.011

Return Climate Period Change

Storm 15 15 15 15 15 15 15 15 15 15 15 15

PN P1.000 P1.001 P1.002 P1.003 P1.004 P1.005 P1.006 P1.007

Winter Winter Winter Winter Winter Winter Winter Winter Winter Winter Winter Winter

2 2 2 2 2 2 2 2 2 2 2 2

First X Surcharge

First Y First Z O/F Lvl Flood Overflow Act. Exc.

0% 10/15 Summer 0% 10/15 Summer 0% 5/15 Winter 0% 100/15 Summer 0% 0% 0% 0% 0% 0% 0% 2/15 Summer 0% 2/15 Summer

Water Flooded Pipe US/MH Level Surch'ed Volume Flow / O'flow Flow Name (m) Depth (m) (m³) Cap. (l/s) (l/s) MH1 MH2 MH3 MH4 MH5 MH6 MH7 MH8

75.003 74.979 74.927 74.743 74.029 72.318 69.760 69.620

-0.197 -0.148 -0.082 -0.225 -0.258 -0.271 -0.708 -0.710

0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000

0.27 0.53 0.96 0.34 0.21 0.17 0.10 0.10

0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

26.7 55.1 85.3 85.0 85.0 85.2 96.9 97.7

Status OK OK OK OK OK OK OK OK

Buro Happold Camden Mill Lower Bristol Road Bath BA2 3DQ Date 23.09.2015 File 160223 HIGHWAY DRAIN... Micro Drainage

Page 8 034233 Green Lane Northwood Station Phase 2 Highway Drainage System Designed by NP Checked by GL Network 2013.1

2 year Return Period Summary of Critical Results by Maximum Level (Rank 1) for Storm

PN P1.008 P1.009 P1.010 P1.011

Water Flooded Pipe US/MH Level Surch'ed Volume Flow / O'flow Flow Name (m) Depth (m) (m³) Cap. (l/s) (l/s) MH9 MH10 MH11 MH12

69.422 69.235 69.175 68.853

-0.870 -0.846 0.113 0.065

0.000 0.000 0.000 0.000

0.07 0.06 1.08 1.59

0.0 0.0 0.0 0.0

Status

97.2 OK 92.9 OK 80.2 SURCHARGED 80.0 SURCHARGED

Buro Happold Camden Mill Lower Bristol Road Bath BA2 3DQ Date 23.09.2015 File 160223 HIGHWAY DRAIN... Micro Drainage

Page 9 034233 Green Lane Northwood Station Phase 2 Highway Drainage System Designed by NP Checked by GL Network 2013.1

5 year Return Period Summary of Critical Results by Maximum Level (Rank 1) for Storm

0.000 2.000 0.800 0.000

Profile(s) Duration(s) (mins)

Summer and Winter 15, 30, 60, 120, 180, 240, 360, 480, 600, 720, 960, 1440 2, 5, 10, 30, 100 0, 0, 30, 30, 30

Return Period(s) (years) Climate Change (%)

PN P1.000 P1.001 P1.002 P1.003 P1.004 P1.005 P1.006 P1.007 P1.008 P1.009 P1.010 P1.011

Return Climate Period Change

Storm 15 15 15 15 15 15 15 15 15 15 15 15

PN P1.000 P1.001 P1.002 P1.003 P1.004 P1.005 P1.006 P1.007

Winter Winter Winter Winter Winter Winter Winter Winter Winter Winter Winter Winter

5 5 5 5 5 5 5 5 5 5 5 5

First X Surcharge

First Y First Z O/F Lvl Flood Overflow Act. Exc.

0% 10/15 Summer 0% 10/15 Summer 0% 5/15 Winter 0% 100/15 Summer 0% 0% 0% 0% 0% 0% 0% 2/15 Summer 0% 2/15 Summer

Water Flooded Pipe US/MH Level Surch'ed Volume Flow / O'flow Flow Name (m) Depth (m) (m³) Cap. (l/s) (l/s) MH1 MH2 MH3 MH4 MH5 MH6 MH7 MH8

75.090 75.070 75.016 74.763 74.043 72.332 69.780 69.640

-0.110 -0.057 0.007 -0.205 -0.244 -0.257 -0.688 -0.690

0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000

0.35 0.67 1.21 0.42 0.27 0.22 0.13 0.12

0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Status

34.4 OK 69.6 OK 107.1 SURCHARGED 106.9 OK 106.8 OK 107.1 OK 120.6 OK 121.0 OK

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5 year Return Period Summary of Critical Results by Maximum Level (Rank 1) for Storm

PN P1.008 P1.009 P1.010 P1.011

Water Flooded Pipe US/MH Level Surch'ed Volume Flow / O'flow Flow Name (m) Depth (m) (m³) Cap. (l/s) (l/s) MH9 MH10 MH11 MH12

69.448 69.303 69.282 68.879

-0.844 -0.778 0.220 0.091

0.000 0.000 0.000 0.000

0.09 0.07 1.21 1.78

Status

0.0 120.3 OK 0.0 110.4 OK 0.0 89.8 SURCHARGED 0.0 89.7 SURCHARGED

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10 year Return Period Summary of Critical Results by Maximum Level (Rank 1) for Storm

0.000 2.000 0.800 0.000

Profile(s) Duration(s) (mins) Return Period(s) (years) Climate Change (%)

PN P1.000 P1.001 P1.002 P1.003 P1.004 P1.005 P1.006 P1.007 P1.008 P1.009 P1.010 P1.011

Return Climate Period Change

Storm 15 15 15 15 15 15 15 15 15 15 15 15

PN P1.000 P1.001 P1.002 P1.003 P1.004 P1.005 P1.006 P1.007

Summer and Winter 15, 30, 60, 120, 180, 240, 360, 480, 600, 720, 960, 1440 2, 5, 10, 30, 100 0, 0, 30, 30, 30

Winter Winter Winter Winter Winter Winter Winter Winter Winter Winter Winter Winter

10 10 10 10 10 10 10 10 10 10 10 10

First X Surcharge

First Y First Z O/F Lvl Flood Overflow Act. Exc.

+30% 10/15 Summer +30% 10/15 Summer +30% 5/15 Winter +30% 100/15 Summer +30% +30% +30% +30% +30% +30% +30% 2/15 Summer +30% 2/15 Summer

Water Flooded Pipe US/MH Level Surch'ed Volume Flow / O'flow Flow Name (m) Depth (m) (m³) Cap. (l/s) (l/s) MH1 MH2 MH3 MH4 MH5 MH6 MH7 MH8

75.390 75.362 75.201 74.839 74.093 72.373 69.854 69.714

0.190 0.235 0.192 -0.129 -0.194 -0.216 -0.614 -0.616

0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000

0.58 1.13 2.14 0.75 0.47 0.38 0.22 0.22

0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Status

57.0 SURCHARGED 116.9 SURCHARGED 189.6 SURCHARGED 190.3 OK 190.2 OK 189.3 OK 210.1 OK 210.7 OK

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10 year Return Period Summary of Critical Results by Maximum Level (Rank 1) for Storm

PN P1.008 P1.009 P1.010 P1.011

Water Flooded Pipe US/MH Level Surch'ed Volume Flow / O'flow Flow Name (m) Depth (m) (m³) Cap. (l/s) (l/s) MH9 MH10 MH11 MH12

69.544 69.524 69.517 68.936

-0.748 -0.557 0.455 0.148

0.000 0.000 0.000 0.000

0.14 0.11 1.45 2.15

0.0 0.0 0.0 0.0

Status

203.6 OK 168.4 OK 107.8 SURCHARGED 107.8 SURCHARGED

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30 year Return Period Summary of Critical Results by Maximum Level (Rank 1) for Storm

0.000 2.000 0.800 0.000

Profile(s) Duration(s) (mins) Return Period(s) (years) Climate Change (%)

PN P1.000 P1.001 P1.002 P1.003 P1.004 P1.005 P1.006 P1.007 P1.008 P1.009 P1.010 P1.011

Return Climate Period Change

Storm 15 15 15 15 15 15 15 15 30 30 30 30

PN P1.000 P1.001 P1.002 P1.003 P1.004 P1.005 P1.006 P1.007

Summer and Winter 15, 30, 60, 120, 180, 240, 360, 480, 600, 720, 960, 1440 2, 5, 10, 30, 100 0, 0, 30, 30, 30

Winter Winter Winter Winter Winter Winter Winter Winter Winter Winter Winter Winter

30 30 30 30 30 30 30 30 30 30 30 30

First X Surcharge

First Y First Z O/F Lvl Flood Overflow Act. Exc.

+30% 10/15 Summer +30% 10/15 Summer +30% 5/15 Winter +30% 100/15 Summer +30% +30% +30% +30% +30% +30% +30% 2/15 Summer +30% 2/15 Summer

Water Flooded Pipe US/MH Level Surch'ed Volume Flow / O'flow Flow Name (m) Depth (m) (m³) Cap. (l/s) (l/s) MH1 MH2 MH3 MH4 MH5 MH6 MH7 MH8

75.640 75.605 75.351 74.885 74.121 72.397 69.891 69.751

0.440 0.478 0.342 -0.083 -0.166 -0.192 -0.577 -0.579

0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000

0.76 1.43 2.71 0.95 0.60 0.48 0.28 0.27

0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Status

74.3 SURCHARGED 147.9 SURCHARGED 240.3 SURCHARGED 241.1 OK 241.0 OK 240.0 OK 265.2 OK 265.6 OK

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30 year Return Period Summary of Critical Results by Maximum Level (Rank 1) for Storm

PN P1.008 P1.009 P1.010 P1.011

Water Flooded Pipe US/MH Level Surch'ed Volume Flow / O'flow Flow Name (m) Depth (m) (m³) Cap. (l/s) (l/s) MH9 MH10 MH11 MH12

69.717 69.710 69.702 68.981

-0.575 -0.371 0.640 0.193

0.000 0.000 0.000 0.000

0.15 0.10 1.62 2.39

0.0 0.0 0.0 0.0

Status

205.6 OK 159.1 OK 120.2 SURCHARGED 120.2 SURCHARGED

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100 year Return Period Summary of Critical Results by Maximum Level (Rank 1) for Storm

0.000 2.000 0.800 0.000

Profile(s) Duration(s) (mins) Return Period(s) (years) Climate Change (%)

PN P1.000 P1.001 P1.002 P1.003 P1.004 P1.005 P1.006 P1.007 P1.008 P1.009 P1.010 P1.011

Return Climate Period Change

Storm 15 15 15 15 15 15 30 30 30 30 30 30

PN P1.000 P1.001 P1.002 P1.003 P1.004 P1.005 P1.006 P1.007

Summer and Winter 15, 30, 60, 120, 180, 240, 360, 480, 600, 720, 960, 1440 2, 5, 10, 30, 100 0, 0, 30, 30, 30

Winter Winter Winter Winter Winter Winter Winter Winter Winter Winter Winter Winter

100 100 100 100 100 100 100 100 100 100 100 100

First X Surcharge

First Y First Z O/F Lvl Flood Overflow Act. Exc.

+30% 10/15 Summer +30% 10/15 Summer +30% 5/15 Winter +30% 100/15 Summer +30% +30% +30% +30% +30% +30% +30% 2/15 Summer +30% 2/15 Summer

Water Flooded Pipe US/MH Level Surch'ed Volume Flow / O'flow Flow Name (m) Depth (m) (m³) Cap. (l/s) (l/s) MH1 MH2 MH3 MH4 MH5 MH6 MH7 MH8

76.228 76.179 75.786 75.200 74.152 72.423 70.055 70.046

1.028 1.052 0.777 0.232 -0.135 -0.166 -0.413 -0.284

0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000

1.05 1.80 3.34 1.16 0.73 0.60 0.29 0.29

0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

102.8 186.5 296.1 295.3 293.9 294.9 280.8 280.3

Status SURCHARGED SURCHARGED SURCHARGED SURCHARGED OK OK OK OK

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100 year Return Period Summary of Critical Results by Maximum Level (Rank 1) for Storm

PN P1.008 P1.009 P1.010 P1.011

Water Flooded Pipe US/MH Level Surch'ed Volume Flow / O'flow Flow Name (m) Depth (m) (m³) Cap. (l/s) (l/s) MH9 MH10 MH11 MH12

70.034 70.025 70.005 69.053

-0.258 -0.056 0.943 0.265

0.000 0.000 0.000 0.000

0.18 0.11 1.86 2.74

0.0 0.0 0.0 0.0

Status

249.0 OK 176.2 OK 137.7 SURCHARGED 137.8 SURCHARGED

DRAINAGE NETWORK MODELLED IN MICRODRAINAGE MH1 P1.000 MH2 P1.001 MH3 P1.002 MH4

P1.003

MH5

P1.004

MH6

P1.005

MH7

P1.006

MH8

P1.007

MH9

P1.008

MH10

P1.009

MH11

Issues

P1.010

MH12 P1.011 MHEXT

Appendix C

Revision 00 4 March 2016 Page 10

Design Note Project

TfL Landholdings at Northwood

Subject

Response to LBH Queries, Item 3 of 8

Project no Date

034233 3 March 2016 Revision

Description

Issued by

Date

Response to LBH Query 3 of 8

EAF

03/03/2016

Introduction

Approved (signature) David Palmer I am approving this document 2016.03.04 15:54:21Z00'00'

Provide validation of the catchments shown in the planning application against the Thames Water (TW) drainage network. Provide details of the overland surface water run-off contributing to Station Approach. Produce an indicative plan showing the expected direction of overland flow in the event that the drainage system proposed on Green Lane is exceeded. Produce a plan showing the expected drainage direction of overland flow along Central Way, including the area around the carpark entrance. Send LBH the dimensions, total length, buried length, maintenance records and details of the planned maintenance, monitoring and repair work for the existing culvert to the south of the site. Planned maintenance, monitoring and repair works should be proposed with consideration of the impact that a blockage of this culvert would have to the proposed, more vulnerable users which will be located adjacent to the culvert. Produce a plan showing the phasing of the development and required enabling works for each phase. Enabling works should include the installation of the required utilities proposed on Central Way. On these plans show for each phase:  direction of proposed drainage;  the location of drainage outflow connections; and  the peak capacity/outflow from these connections. Provide commentary on the outflow from the proposed oversized pipes to the existing culvert at the south of the site. In this commentary provide a comparison of the pipe diameters of the outlet from the oversized pipes and the existing culvert at the south of the site.

This Technical Note provides the information requested by LBH for item 3 of the above.

Post-Development Drainage paths resulting from an Exceedance Event at Station Approach

LBH has requested that a plan be produced to show the flow paths that would result post-development during a storm water event greater than the Design Flood Event of 1 in 100 years plus climate change. It should be noted that there is no requirement under the NPPF or any other code or regulation to demonstrate events greater than the Design Flood Event and the information provided within this technical note is therefore indicative only. Figure 2â&#x20AC;&#x201D;1 illustrates the indicative drainage paths of overland flow exceeding the drainage system.

Page 2 of 4

Design Note

Figure 2â&#x20AC;&#x201D;1: Indicative drainage paths of overland runoff exceeding the Station Approach drainage system

Design Note It should be noted that the capacity of the proposed Station Approach drainage system (1 in 100 year + climate change) is considered to provide adequate protection from stormwater flooding to the development and is entirely consistent with current planning guidance.

Appendix D

Revision 00 4 March 2016 Page 11

Design Note Project

TfL Landholdings at Northwood

Subject

Response to LBH Queries, Item 4 of 8

Project no Date

034233 29 February 2016 Revision

Description

Issued by

Date

Response to LBH Query 4 of 8

29/02/2016

Approved (signature)

Introduction

This Technical Note provides the information requested by LBH for item 4 of the above.

Expected Drainage Direction of Overland Flow Along Central Way

The overland flow along the Central Way, including the area around the car park entrance, is illustrated in the Figure 2-1 below.

Figure 3â&#x20AC;&#x201D;1: Plan showing the expected drainage direction along the Central Way including the car park entrance.

The overland flow along the Central Way is expected to flow down the slope where the flow will be captured at the bottom by the proposed newly installed linear drain as cut off drain and road gullies. The road level at the top of the Central Way is proposed to be sitting at +78.864m. The level is then slope down to the bottom of the Central Way, where the car park entrance is located, at+72.000m. The road level is then raised by 100mm to reach the car park entrance so that the overland flow is flowing away from the entrance. A number of gullies are proposed at the Central Way to collect the surface water runoff including a linear drain at the downhill of the Central Way as a cut off drain. An additional linear drain is also proposed at the car park entrance as a secondary defence to intercept any surface water runoff.

Page 2 of 2

Appendix E

Revision 00 4 March 2016 Page 12

Technical Note Project

TfL Landholdings at Northwood

Subject

Response to LBH Queries, Item 5 of 8

Project no Date

034233 29 February 2016 Revision

Description

Issued by

Date

Response to LBH Query 5 of 8

29/02/2016

Approved (signature)

Introduction

This Technical Note provides the information requested by LBH for item 5 of the above.

Existing Culvert Asset Information from TfL

m /s

Refer to Appendix A for further asset information. LBH has confirmed and agreed to condition the management and maintenance plan for all phases, and the plan will include the following:   

Thames Water adoption; adoption by others; and requirements to manage the existing culvert in the long run.

Page 2 of 3

Technical Note Appendix A: Existing Culvert Information from TfL

Uncontrolled Copy Confirm validity before use

SAIssue / Revision Description:

Date:

14/05/2012

First Issue Inspectorâ&#x20AC;&#x2122;s Declaration

Development:

Job Title

[Excludes A0g]

B&S Inspector

Name

Signature

SAVILL FREDERICK

Contact No.

07904834071

Date

24/08/12

To the best of my knowledge and belief, I have examined this asset fully in accordance with Engineering Standard E3701 and this report represents a faithful record of the examination with no omissions or misrepresentations (except where may otherwise be noted)

Report Review

1.1.1.3

Job Title

*Approved: [A0g added]

Inspection Engineer

*Approved:

Inspection Manager

Name

Signature

Jim Hughes

Date

19 March 13 /

* Excluding any entries in A0g entered by Maintenance Engineer, Asset Manager & Asset Engineer Document Status: Client:

Originator:

LUL Templar House 81-87 High Holborn London WC1V 6NU ď&#x20AC;¨ 020 7038 5000

Asset Location:

Line Location

Project:

Metropolitan NORTHWOOD/NORTHWOOD HILLS

Document Title:

CDU AP Bridges and Structures Inspection Programme

Principal Inspection of SFL:MR62 CULVERT (>600 MM) TRACKSIDE

LCS & Asset Number:

M066/MR62

Date Inspected:

14/05/2012

Format

A4/A3

Document Number

Revision

The original master of this document is retained on the Document Management & Collaboration Database. Copies produced from the master, by whatever means, are deemed uncontrolled. You must confirm that you hold the latest version, before using this document for its intended purpose.

CONTENTS Section 1 A0g Referral Sheet Sheet inserted by Inspection Engineer. (Excluding any entries in A0g entered by Maintenance Engineer, Asset Manager & Asset Engineer)

Section 2 A0a Bridge & Structure General Reference Sheet Section 3 A0b Inspection & Maintenance Summary Section 4 A0c Defect Description Section 5 A0d Inspection Details (Including annotated photographs, sketches, tunnel sheets etc)

Section 6 A1a â&#x20AC;&#x201C; A24a Inspection Report Summary (Appropriate scoring sheets selected to suit type of structure inspected)

To assist future inspection planning please provide the following information

Information about access:-

(Give details about keys, route & entry, contact personnel, specialist equipment used etc)

The North end of MR62 is accessible via a road which runs behind Northwood station car park. There is an S1 gate down the embankment to the immediate left of the road at the end of the car park, this S1 gate leads to a small fenced off area where the North end of the Culvert is visible. The South end was NOT accessible and was blocked off by a boundary fence and a construction site which was un-manned & locked. The South headwall was partly visible from the embankment behind the cable runs.

Bridges & Structures Principal Inspection Report Referral A0g M066

LCS code

MR62

Asset No

NORTHWOOD/NORTHWOOD HILLS

Line

Metropolitan

Location

Owner

Londn Underground Ltd

Maintainer

Structure

Culvert (over 600mm)

Asset subject to special inspections

PI Inspection frequency

4 YEARS

Date of last PI

Civils & Trk Mngr SSL

02/03/2010 Date of this PI

14/05/2012

Ellipse order number

51430823001

Summary position This structure has been examined in accordance with engineering standard E3701 and found to be: Headwalls Serviceable Element Invert North South Average condition Condition Score 81.25% 87.5% 50.0% 68.75% From Principal Inspection Report Assessment Rating from Structural Assessment Report Condition score

68.75%

Lowest Item score

No assessment

Pass



Capacity Ratio

Fail

2.12

Elements classified B2 or less (scoring 6 or less) Element No Element Invert 3 Open Fracture to the North end of culvert, 5mm- see photo 7. South side – Not visible 11 Minor areas of mortar loss and heavy water seepage to the wingwall at the north Training walls end of the culvert- see photo 4. South wingwall in poor condition, partially visible - see photo 11 27 water seepage & missing brickwork – See photos 6&7 N Headwall 26 Invert ring was showing signs of miss-alignment and displaced brickwork as S Headwall shown in a partial view of the headwall in photo 10 27 Partial view of the South headwall in Photo 10 shows the condition of the tunnel ring to be in poor condition, displaced and miss-aligned brickwork. Note, asset has not been assessed

Performance Rating to CED-ST-1111 Ideal Desirable



Essential minimum condition Unacceptable

General Condition Standard *Metronet (see asset condition assessment standard 2Information 01015-001) More Information required OR Failure to meet duty (Extra inspections or protection required)

Failure to meet duty

Failure

5% %

Immediate replacement, modification or overhaul required D Extraordinary operations or maintenance regime required

Major overhaul required after 1-5 years C

X2011806 scour X2013832 brickwork



(Withdrawn from duty)

*Asset Manager (AM) Information ACA Concerns etc

Grey

Major overhaul required after 6-10 B years No major overhaul required A Life > 10 years,



Indicate, tick as appropriate *Note: Metronet information to be completed by the Asset Manager (AM)

90% Total 100%

LCS code

M066

MR62

Asset No

Safety assessments

Yes



Immediate safety action was carried out by the inspector Asset recommended for a Special Inspection every work is complete Details of safety action taken :

weeks until inspections confirm

Follow Up

Report Referral :



Maintenance Engineer’s corresponding action

Inspection Review Engineer’s recommendations Item No

(including any work order details)

Inspector raised fault regarding fence line restricting access. Suggest this is considered when the LOT A scoping (WO 51699122) is undertaken. Raised after this inspection Brickwork repairs subject of work orders 08800858 & 50447856 see annotated Ellipse work order printout attached Vegetation removal subject of work order 51706310. Raised after this inspection

Report certified by Chartered Civil or Structural Engineer (excludes Asset Manager, Maintenance Engineer & Asset Engineer entries)

Name

Jim Hughes

Signed

Report addressed by Maintenance Engineer

Tracking Work Order Name 51531523

Date 19 March 13

Signed

Date

Follow up column for subsequent inspection use only. A copy of this A0g to be attached to subsequent inspection reports. Follow up inspector to initial column to confirm item was reviewed at follow up superficial / special inspections.

Asset Manager [optional]: Remarks:

Signed

Asset Engineer [optional]: Remarks:

Date

Signed

Date

5 LONDON UNDERGROUND LIMITED

FORM A0a

BRIDGE AND STRUCTURE GENERAL REFERENCE SHEET STRUCTURE TYPE LINE NEAR OWNER APPLICATION: * BRIDGE * STRUCTURE * DELETE AS NECESSARY

MINIMUM CLEARANCES MINIMUM HEADROOM TO

Culvert (over 600mm) REFNo M066/MR62 Metropolitan NORTHWOOD/NORTHWOOD HILLS Londn Underground Ltd

RIVER - NONNAVIGABLE * UNDER * OVER * ADJACENT

* LUL RAIL * ROAD * RIVER (NAVIGABLE/NON-NAVIGABLE) * CANAL * MAINLINE RAILWAY N.BOUND S.BOUND E.BOUND W.BOUND

* RAIL ROADWAY FOOTWAY

N.BOUND S.BOUND E.BOUND W.BOUND MINIMUM TRANSVERSE to * RAIL * DELETE AS NECESSARY ROADWAY RESRICTIONS: WARNING SIGNS LOADING YES / NO * HEADROOM YES / NO * * DELETE AS NECESSARY WIDTH YES / NO * STATUTORY UNDERTAKERS USING BRIDGE OR STRUCTURE LUL ONLY GENERAL PHOTOGRAPH

CONSTRUCTION DETAILS BRIDGES: SPANNING STRUCTURES (INCLUDES VIADUCTS, TUNNELS, SUBWAYS, CULVERTS AND ROOFS ETC) STANDING STRUCTURES (INCLUDES WALLING, LIGHTING, CHIMNEYS AND SUMPS ETC)

SITE PLAN

Description: General view of the track above MR62

NATIONAL GRID REF ROAD NAME/NUMBER BUS ROUTE Y/N - NUMBER LOCAL AUTHORITY/BOROUGH DECK MATERIALS TYPE OF CONSTRUCTION FORM OF DECK END SUPPORTS INTERMEDIATE SUPPORTS NATURE OF FOUNDATIONS BEARINGS TYPE BEARINGS MANUFACTURER PARAPETS WATERPROOFING WALL/FRAME TYPE OF CONSTRUCTION FORM FOUNDATIONS/FOOTINGS STRUTS/TIES/ANCHORS ANCILLARIES: FLOORS LADDERS LIGHTING UNITS PARAPETS MACHINERY

Construction bricks Circular brick barrel culvert North & South Headwall N/A N/V N/V N/V N/V N/V

Sheet updated

24/08/2012

TQ 09246 91453 Station approach N HILLINGDON PLAN ROOM DRAWING NUMBER (CURRENT DRAWINGS ONLY)

LCS: M066 ASSET NUMBER: M066/MR62

INSPECTION AND MAINTENANCE SUMMARY Construction details Were any unusual construction details noted on the records or during the inspection? e.g. Asset been altered/extended, unusual combination of construction materials such as cast iron with steel, carbon fibre, temporary or permanent propping If *yes, give details

*Yes

No X

Scour Is the asset identified as a Scour Risk in LUL Document, G-058 Manual of Good Practice

*Yes

If yes, what is the Scour Rating

Handbook 47

EX2502 Priority 3

If *yes, give details of any previously identified scour issues that require inspection. (Note :- Actual finding / results etc from this inspection to be recorded on the A0c form)

INSPECTION SUMMARY DATE

14/05/12

Construction Date : 1887 TYPE *

DEFECT AND ACTION RECOMMENDED **

SUP / PR / SP

-Arrange access to the south headwall within the next 3 months so that a full inspection can be completed.

MAINTENANCE WORKS SUMMARY

-Provide a gate so the south headwall can be accessed. 02/03/10

SUP / PR / SP

Provide proper entrance to south headwall

02/03/10

SUP / PR / SP

Brickwork repair

19/04/01

SUP / PR / SP

Brickwork repair

*INSPECTION TYPE: SUP = Superficial PR = Principal SP = Special (Delete as Applicable) ** ACTION RECOMMENDED: See Inspection Report for Details

DEFECT DESCRIPTION LCS/Structure No: M066 / MR62

A0c

Number of ID Plates present: 0

Name of Inspector: SAVILL FREDERICK

Inspection Date: 14/05/2012

Location: NORTHWOOD/NORTHWOOD HILLS Item Scoring Ref Sheet

Description

Type

General

Defects Description (please state if defects are above 2m height)

Recommendation & Approx Quantity

MR62 is a masonry barrel single span culvert which runs underneath the track between Northwood and Northwood Hills stations on the Metropolitan line. The North end of the asset is accessible from a road which runs behind the station car park. The embankment to the left of this road leads down to an S1 gate which can be opened to gain access to the North end of the asset. The South end of the asset was NOT ACCESSIBLE and a full inspection was not able to be completed on this part of the asset. A boundary fence and a locked, un-manned construction site was restricting access. In the previous report it was noted that “there should be a proper gate installed at the south end to provide access to the south headwall” this is still the case.

Defects Non inspection of South side of asset

Due to the access issue above, the south headwall, south wing wall & south side invert was unable to be fully inspected. From looking through the fence at site, photo 10, the condition of the south side was poor. Missing bricks and miss-aligned brickwork were noted. The previous reports, assessment history and W/O’s s show that this has been the case since 1994. Combining the fact that what was visible of the asset is in poor condition and that access was restricted I was unable to assess the condition of the South side in full so I have submitted this as a partial inspection with only 50% of the asset completed. The scores are based on what I have seen in photos 3, 10 & 11.

Recommend access be granted within the next three months so that a full Pi can be completed and/or a special inspection can be completed on the areas that aren’t visible & remedial works can begin. A proper gate also needs to be installed so that it can be accessed in the future.

A5a

No. 03

Condition of invert

The North end of the culvert has a fracture which was Monitor the fracture at the measured to be open by 5mm and 500mm in length – see next general inspection. photo 7

A5a

No. 11

Condition of Wing walls

The Wing wall to the North end of the asset was 50% Monitor at next inspection covered by moss growth. There was water running down the wall from an inlet pipe and isolated spalling – see photo 4. South end of the asset was only partially visible but heavy spalling to the base of the concrete wing wall was noted – see photo 11

A5a

No. 27

Condition of headwall – North

Missing brickwork was noted to the barrel ring of the Monitor at next inspection North headwall – see photos 6 & 7

No. 26 & Condition of headwall 27 - South

Photos 3, 10 & 11 show the partial views of the south side Arrange access so that a full of the asset. It shows the displacement and miss-aligned inspection or special brickwork to the invert ring on the headwall. inspection can be completed.

A5a

Headwall repairs

Pipe presents circumferencial fractures at 4 locations and a hole at 9m from MH of M066. Clean and repair culvert. Ref:RPT-BAS-M066-5000336 Related W/O all closed:V1317311, 00702986, 00800857 PM.15/10/09

Outstanding brickwork repair W/Oâ&#x20AC;&#x2122;s since 2006 & 2009

10 Snapshot taken from assessment report

From: Savill Frederick Sent: 14 August 2012 11:04 To: Fahey Sean; Crawley Ingrid Subject: M066-MR62

Sean, Ingrid, Whilst inspecting Culvert MR62 between Northwood & Northwood Hills I was unable to gain access to the South headwall as there was a fenced off construction site preventing Access. There was no work going on at the time and no security to speak to. The South headwall was in bad condition, brickwork displacement & scour is visible in the photos I have attached. I was only able to get photos of the south headwall from over the boundary fence and I was unable to get a picture looking directly into the culvert. Access needs to be allowed so a full inspection can be undertaken and works to rectify the defects can begin. If you need any more info on this fault please let me know cheers Freddie Freddie Savill| Bridges and Structures Inspector London Underground | Templar House 2nd floor Eagle Wing 81-87 High Holborn London WC1V 6NU Mobile +44 (0) 07904 834071

Frederick.savill@tube.tfl.gov.uk

ď ? Please consider the environment before printing this document ď &#x160;

12 A0d

2 LCS / STRUCTURE No. M066 / M066/MR62 2.1.1 INSPECTION DETAILS (Including annotated photographs, sketches, tunnel sheets etc)

2.1.2 General Photo 1:

General view of the North side of the culvert looking South Photo 2: General view of the tracks above the culvert looking North

13 Photo 3:

General view of the South side of the culvert, which was only partially visible due to a boundary fence and a locked, un-manned construction site.

2.1.3 DEFECT PHOTOGRAPH & Description Photo 4: A view of the

wingwall to the North side of the culvert. Minor spalling is visible along with moss growth covering 50% of the wall.

Vegetation

Build up of debris

Photo 5: A view of the stream running away from the north end of the culvert underneath a boundary fence and into the back gardens of the houses opposite. A build up of debris can be seen and vegetation growing the fence.

Photo 6: Shows a section of missing brickwork to the invert at the North end of the culvert.

Photo 7: An open fracture just inside the North end of the culvert. The missing brickwork in photo 6 is visible to the bottom left of this photo (green outline) The fracture was measured and it was found to be open by 5mm.

Photo 8: The embankment above the culvert headwall is being retained by a timber which has become rotten and allowing the embankment to slip into the culvert below. Photo 9:

Another view of the embankment and the rotten timbers retaining the earth above the headwall. The metal spikes that have been driven into the ground to stop the timbers from displacing have also become loose and are showing signs of movement.

17 Photo 10: A view of the South

headwall and invert entrance which was only partially visible, taken by holding the camera over the fence. A boundary fence was restricting access along with an un-manned, locked constrcution site. What was visible of the culvert made it clear that it was in poor condition. A Fault was raised regarding Access to allow the inspection to be completed.

Photo 11: View

showing the concrete wing wall and inlet pipe to the south side of the asset. Heavy spalling to the base of the concrete wing wall was noted and a hairline fracture is also visible. I was unable to take any measurements of the spalling due to access issues.

19 CULVERT INSPECTION REPORT SUMMARY Structure No / Location: Date of Inspection:

M066 / M066/MR62

14/05/2012

A5a (Form 1 of 2)

Inspector's Name:

SAVILL FREDERICK

Weather / Temp:

RAIN / 13 deg C

SUBSTRUCTURE DETAILS ITEM INVERT, APRON, ABUTMENTS REF

WING

WALLS, COMMENT AND CONSTRUCTION MATERIAL

PRINCIPAL

DEFECTS

ITEM

SCORE

* 6 Alignment

* 7 Condition

* 15 Alignment (Wall 1 - Specify)

* 16 Condition (Wall 1 - Specify)

* 17 Alignment (Wall 2 - Specify)

* 18 Condition (Wall 2 - Specify)

Invert: 1 Arrangement

cirular brick culvert

* 2 Alignment

North end – As constructed South end – Not visible Open Fracture to the North end of culvert, 5mm- see photo 7. South side – Not visible South side of the culvert was NOT visible due to the boundary fence and locked, unmanned construction site. Recommend Immediate access so that a full PI or special inspection can be completed.

* 3 Condition

4 Other Comments ...............

Apron: 5 Arrangement

8 Other Comments ............... Wing Walls (River Training Walls): 9 Arrangement

Masonry wingwalls

* 10 Alignment

North side - as constructed. South side serviceable condition partially visible (photo 10) Minor areas of mortar loss and heavy water seepage to the wingwall at the north end of the culvert- see photo 4. South wingwall in poor condition, partially visible - see photo 11

* 11 Condition

12 Other Comments ............... Abutments (Side Walls): 13 Foundations 14 Arrangement

19 Drainage 20 Other Comments Service Pipes / Cables by Culvert

Carried

Indicate items not applicable (N/A) or not visible (N/V) * Items to receive an 'Item Score' if item is applicable

(X)

No. of ITEMS SCORED (Y)

TOTAL ITEM SCORE

OVERALL ELEMENT RATING (X ÷ Y) x 12.5 =

81.25%

CULVERT INSPECTION REPORT SUMMARY Structure No / Location: Date of Inspection:

M066 / MR62

A5a (Form 2 of 2)

Inspector's Name:

SAVILL FREDERICK

Weather / Temp:

RAIN / 13 deg C

14/05/2012

SUPERSTRUCTURE DETAILS ITEM ROOF, HEADWALLS / REVETMENTS, COMMENT AND PARAPETS CONSTRUCTION MATERIALS REF

PRINCIPAL

DEFECTS

ITEM

SCORE

* 22 Alignment

* 23 Condition

Roof: 21 Arrangement

n/v

24 Other Comments ................ Headwalls / Revetments: 25 Arrangement

North headwall - brick

* 26 Alignment

as constructed

* 27 Condition

water seepage & missing brickwork – See photos 6&7 Earth directly above north headwall needs to be stabilized. Timber & metal rods used as a retaining wall has become rotten and loose and needs replacing – see photos 8&9

* 30 Alignment

* 31 Condition

28 Other Comments ................

Parapets: 29 Arrangement

32 Other Comments ................ Embankment / Surfacing Over: 33 Condition

tracks

34 Other Comments ................

Indicate items not applicable (N/A) or not visible (N/V) * Items to receive an 'Item Score' if item is applicable

(X)

No. of ITEMS SCORED (Y)

TOTAL ITEM SCORE

OVERALL ELEMENT RATING (X ÷ Y) x 12.5 =

1. A B C

EXTENT (E) Less than 5% Between 5% and 10% Between 10% and 20%

2. 1 2 3

Greater than 20%

RECOMMENDED (R) Replace Paint Repair Monitor Inspect

C P R M I

ACTION

EXTENT/SEVERITY RATING ITEM SCORE

87.5%

SEVERITY (S) No ‘significant defect’ ‘Minor’ – defect of a non – urgent nature ‘Heavy’ – defects of an unacceptable nature which shall be included for attention within the next two annual maintenance programmes ‘Severe’ – defects where action is needed (these shall be reported immediately to the supervisor). These defects shall require action within the next financial year. PRIORITY (P)

I H M L R

Immediate High (within 12 months) Medium (within 2 years) Low (before next principal inspection) Review (for assessment at next principal inspection)

CULVERT INSPECTION REPORT SUMMARY Structure No / Location: Date of Inspection:

M066 / MR62

14/05/2012

A5a (Form 2 of 2)

Inspector's Name:

SAVILL FREDERICK

Weather / Temp:

RAIN / 13 deg C

SUPERSTRUCTURE DETAILS ITEM ROOF, HEADWALLS / REVETMENTS, COMMENT AND PARAPETS CONSTRUCTION MATERIALS REF

PRINCIPAL

DEFECTS

ITEM

SCORE

* 22 Alignment

* 23 Condition

* 30 Alignment

* 31 Condition

Roof: 21 Arrangement

n/v

24 Other Comments ................ Headwalls / Revetments: 25 Arrangement

South headwall – partially visible

* 26 Alignment

Invert ring was showing signs of missalignment and displaced brickwork as shown in a partial view of the headwall in photo 10. Partial view of the South headwall in Photo 10 shows the condition of the tunnel ring to be in poor condition, displaced and miss-aligned brickwork.

* 27 Condition

28 Other Comments ................ Parapets: 29 Arrangement

32 Other Comments ................ Embankment / Surfacing Over: 33 Condition

Tracks

34 Other Comments ................

Indicate items not applicable (N/A) or not visible (N/V) * Items to receive an 'Item Score' if item is applicable

(X)

No. of ITEMS SCORED (Y)

TOTAL ITEM SCORE

OVERALL ELEMENT RATING (X ÷ Y) x 12.5 =

1. A B C

EXTENT (E) Less than 5% Between 5% and 10% Between 10% and 20%

2. 1 2 3

Greater than 20%

RECOMMENDED (R) Replace Paint Repair Monitor Inspect

C P R M I

ACTION

EXTENT/SEVERITY RATING ITEM SCORE

50.00%

I H M L R

Immediate High (within 12 months) Medium (within 2 years) Low (before next principal inspection) Review (for assessment at next principal inspection)

Appendix F

Revision 00 4 March 2016 Page 13

Technical Note Project

TfL Landholdings at Northwood

Subject

Response to LBH Queries, Item 6 of 8

Project no Date

034233 29 February 2016 Revision

Description

Issued by

Date

Response to LBH Query 6 of 8

29/02/2016

Approved (signature)

Introduction

This Technical Note provides the information requested by LBH for item 6 of the above.

Ordnance Survey, (c) Crown Copyright 2015. All rights reserved. Licence number 100022432 All Rights reserved. Buro Happold and its group companies assert (unless otherwise agreed in writing) their rights under s.77 to 89 of the Copyright, Designs and Patents Act 1988.

DO NOT SCALE THIS DRAWING.

HEALTH AND SAFETY INFORMATION IN ADDITION TO THE HAZARDS/RISKS NORMALLY ASSOCIATED WITH THE TYPES OF WORK DETAILED ON THIS DRAWING, NOTE THE FOLLOWING CONSTRUCTION.

MAINTENANCE/CLEANING/OPERATION.

DECOMMISSIONING/DEMOLITION.

Notes 1.

THIS DRAWING TO BE READ IN CONJUNCTION WITH DRAWINGS: 034233_C3110 TO C3112.

THIS LAYOUT PLAN IS BASED ON: FLETCHER PRIEST ARCHITECTS DRAWINGS RECEIVED ON 19th FEB 2016. THAMES WATER ASSET LOCATION SEARCH SEWER MAP.

EXISTING SEWER INFORMATION IS INDICATIVE ONLY.

LEGEND

EX (LIN IST E ING AS C CA SU UL VE PA ME VE LO CIT D) RT CIT Y Y = 25 =3 2 .96 3 l/s 5m /s

Q restricted = 0.9 l/s

PROPOSED SURFACE WATER CONNECTION TO EXISTING CULVERT Q - 2YR = 75.9 l/s Q - 10YR = 105.5 l/s Q - 30YR = 117.7 l/s Q - 100YR = 134.8 l/s *FROM WINDES CALCULATION INCLUDING WIDER CATCHMENT

INITIAL ISSUE

Rev Description

26.02.16

Date

Drn

Ch'd

INFORMATION Status of drawing

NEW DRAINAGE WORKS AT GREEN LANE TO CONNECT INTO CENTRAL WAY THROUGH PHASE 4 TO THE SOUTH OF THE SITE ARE TO BE CARRIED OUT IN PHASE 1.

Camden Mill Lower Bristol Road Bath BA2 3DQ UK Architect

Tel:

+44 (0)1225 320600

Fax:

+44 (0)870 787 4148

Email: 034233@burohappold.com Web: www.burohappold.com

FLETCHER PRIEST ARCHITECTS

Project Drg Title

Scales@A1

Job No.

Drawn by Checked by

Drawing No.

Date

Rev

034233 C3120

DO NOT SCALE THIS DRAWING.

HEALTH AND SAFETY INFORMATION IN ADDITION TO THE HAZARDS/RISKS NORMALLY ASSOCIATED WITH THE TYPES OF WORK DETAILED ON THIS DRAWING, NOTE THE FOLLOWING CONSTRUCTION.

MAINTENANCE/CLEANING/OPERATION.

DECOMMISSIONING/DEMOLITION.

Notes 1.

THIS DRAWING TO BE READ IN CONJUNCTION WITH DRAWINGS: 034233_C3110 TO C3112.

THIS LAYOUT PLAN IS BASED ON: FLETCHER PRIEST ARCHITECTS DRAWINGS RECEIVED ON 19th FEB 2016. THAMES WATER ASSET LOCATION SEARCH SEWER MAP.

EXISTING SEWER INFORMATION IS INDICATIVE ONLY.

LEGEND

EX (LIN IST E ING AS C CA SU UL VE PA ME VE LO CIT D) RT CIT Y Y = 25 =3 2 .96 3 l/s 5m /s

PROPOSED SURFACE WATER CONNECTION TO EXISTING CULVERT Q - 2YR = 75.9 l/s Q - 10YR = 105.5 l/s Q - 30YR = 117.7 l/s Q - 100YR = 134.8 l/s *FROM WINDES CALCULATION INCLUDING WIDER CATCHMENT

INITIAL ISSUE

Rev Description

26.02.16

Date

Drn

Ch'd

INFORMATION Status of drawing

EXISTING DRAINAGE IS TO BE REMOVED / ABANDONED / DIVERTED TO MAKE WAY FOR THE BASEMENT EXCAVATION WORKS

Camden Mill Lower Bristol Road Bath BA2 3DQ UK Architect

Tel:

+44 (0)1225 320600

Fax:

+44 (0)870 787 4148

Email: 034233@burohappold.com Web: www.burohappold.com

FLETCHER PRIEST ARCHITECTS

Project Drg Title

Scales@A1

Job No.

Drawn by Checked by

Drawing No.

Date

Rev

034233 C3121

DO NOT SCALE THIS DRAWING.

HEALTH AND SAFETY INFORMATION IN ADDITION TO THE HAZARDS/RISKS NORMALLY ASSOCIATED WITH THE TYPES OF WORK DETAILED ON THIS DRAWING, NOTE THE FOLLOWING CONSTRUCTION.

MAINTENANCE/CLEANING/OPERATION.

DECOMMISSIONING/DEMOLITION.

Notes 1.

THIS DRAWING TO BE READ IN CONJUNCTION WITH DRAWINGS: 034233_C3110 TO C3112.

THIS LAYOUT PLAN IS BASED ON: FLETCHER PRIEST ARCHITECTS DRAWINGS RECEIVED ON 19th FEB 2016. THAMES WATER ASSET LOCATION SEARCH SEWER MAP.

EXISTING SEWER INFORMATION IS INDICATIVE ONLY.

LEGEND

EX (LIN IST E ING AS C CA SU UL VE PA ME VE LO CIT D) RT CIT Y Y = 25 =3 2 .96 3 l/s 5m /s

Q restricted = 0.9 l/s

Q restricted = 3.9 l/s

PROPOSED SURFACE WATER CONNECTION TO EXISTING CULVERT Q - 2YR = 78.5 l/s Q - 10YR = 107.0 l/s Q - 30YR = 119.3 l/s Q - 100YR = 136.7 l/s *FROM WINDES CALCULATION INCLUDING WIDER CATCHMENT

INITIAL ISSUE

Rev Description

26.02.16

Date

Drn

Ch'd

INFORMATION Status of drawing

INSTALL BEANY KERB ALONG THE NEW KERBLINE AT GREEN LANE AND ATTENUATION TANK AT PODIUM LEVEL

Camden Mill Lower Bristol Road Bath BA2 3DQ UK Architect

Tel:

+44 (0)1225 320600

Fax:

+44 (0)870 787 4148

Email: 034233@burohappold.com Web: www.burohappold.com

FLETCHER PRIEST ARCHITECTS

Project Drg Title

Scales@A1

Job No.

Drawn by Checked by

Drawing No.

Date

Rev

034233 C3122

DO NOT SCALE THIS DRAWING.

HEALTH AND SAFETY INFORMATION IN ADDITION TO THE HAZARDS/RISKS NORMALLY ASSOCIATED WITH THE TYPES OF WORK DETAILED ON THIS DRAWING, NOTE THE FOLLOWING CONSTRUCTION.

MAINTENANCE/CLEANING/OPERATION.

DECOMMISSIONING/DEMOLITION.

Notes 1.

THIS DRAWING TO BE READ IN CONJUNCTION WITH DRAWINGS: 034233_C3110 TO C3112.

THIS LAYOUT PLAN IS BASED ON: FLETCHER PRIEST ARCHITECTS DRAWINGS RECEIVED ON 19th FEB 2016. THAMES WATER ASSET LOCATION SEARCH SEWER MAP.

EXISTING SEWER INFORMATION IS INDICATIVE ONLY.

LEGEND

EX (LIN IST E ING AS C CA SU UL VE PA ME VE LO CIT D) RT CIT Y Y = 25 =3 2 .96 3 l/s 5m /s

Q restricted = 0.9 l/s

Q restricted = 0.9 l/s Q restricted = 0.9 l/s Q restricted = 0.9 l/s

Q restricted = 3.9 l/s

PROPOSED SURFACE WATER CONNECTION TO EXISTING CULVERT Q - 2YR = 80.0 l/s Q - 10YR = 107.8 l/s Q - 30YR = 120.2 l/s Q - 100YR = 137.8 l/s *FROM WINDES CALCULATION INCLUDING WIDER CATCHMENT

INITIAL ISSUE

Rev Description

26.02.16

Date

Drn

Ch'd

INFORMATION Status of drawing

NEW DRAINAGE WORKS AT THE SOUTHERN END OF THE SITE

Camden Mill Lower Bristol Road Bath BA2 3DQ UK Architect

Tel:

+44 (0)1225 320600

Fax:

+44 (0)870 787 4148

Email: 034233@burohappold.com Web: www.burohappold.com

FLETCHER PRIEST ARCHITECTS

Project Drg Title

Scales@A1

Job No.

Drawn by Checked by

Drawing No.

Date

Rev

034233 C3123

Appendix G

Revision 00 4 March 2016 Page 14

Technical Note Project

TfL Landholdings at Northwood

Subject

Response to LBH Queries, Item 7 of 8

Project no Date

034233 29 February 2016 Revision

Description

Issued by

Date

Response to LBH Query 7 of 8

29/02/2016

Approved (signature)

Introduction

This Technical Note provides the information requested by LBH for item 7 of the above.

DO NOT SCALE THIS DRAWING.

HEALTH AND SAFETY INFORMATION IN ADDITION TO THE HAZARDS/RISKS NORMALLY ASSOCIATED WITH THE TYPES OF WORK DETAILED ON THIS DRAWING, NOTE THE FOLLOWING CONSTRUCTION.

MAINTENANCE/CLEANING/OPERATION.

DECOMMISSIONING/DEMOLITION.

Notes 1.

THIS DRAWING TO BE READ IN CONJUNCTION WITH 034233_C3111 AND 034233_C3112.

THIS LAYOUT PLAN IS BASED ON: FLETCHER PRIEST ARCHITECTS DRAWINGS RECEIVED ON 19th FEB 2016. THAMES WATER ASSET LOCATION SEARCH SEWER MAP.

EXISTING SEWER INFORMATION IS INDICATIVE ONLY.

REVISED ISSUE

26.02.16

SECOND ISSUE

16.12.15

MCD NP

INITIAL ISSUE

06.10.15

MCD NP

Date

Drn

Rev Description

INFORMATION Status of drawing

Camden Mill Lower Bristol Road Bath BA2 3DQ UK Architect

Tel:

+44 (0)1225 320600

Fax:

+44 (0)870 787 4148

Email: 034233@burohappold.com Web: www.burohappold.com

FLETCHER PRIEST ARCHITECTS

Project Drg Title

80 1 : 1000

SCALE BEFORE REDUCTION

Scales@A1

Job No.

Drawn by Checked by

Drawing No.

Date

Rev

034233 C3110

Ch'd

DO NOT SCALE THIS DRAWING.

HEALTH AND SAFETY INFORMATION IN ADDITION TO THE HAZARDS/RISKS NORMALLY ASSOCIATED WITH THE TYPES OF WORK DETAILED ON THIS DRAWING, NOTE THE FOLLOWING CONSTRUCTION.

MAINTENANCE/CLEANING/OPERATION.

DECOMMISSIONING/DEMOLITION.

Notes 1.

THIS DRAWING TO BE READ IN CONJUNCTION WITH 034233_C3110 AND 034233_C3112.

THIS LAYOUT PLAN IS BASED ON: FLETCHER PRIEST ARCHITECTS DRAWINGS RECEIVED ON 19th FEB 2016. THAMES WATER ASSET LOCATION SEARCH SEWER MAP.

EXISTING SEWER INFORMATION IS INDICATIVE ONLY.

REVISED ISSUE

26.02.16

SECOND ISSUE

16.12.15

MCD NP

INITIAL ISSUE

06.10.15

MCD NP

Date

Drn

Rev Description

INFORMATION Status of drawing

Camden Mill Lower Bristol Road Bath BA2 3DQ UK Architect

Tel:

+44 (0)1225 320600

Fax:

+44 (0)870 787 4148

Email: 034233@burohappold.com Web: www.burohappold.com

FLETCHER PRIEST ARCHITECTS

Project Drg Title

40 1 : 500 Scales@A1

SCALE BEFORE REDUCTION

Job No.

Drawn by Checked by

Drawing No.

Date

Rev

034233 C3111

Ch'd

DO NOT SCALE THIS DRAWING.

HEALTH AND SAFETY INFORMATION IN ADDITION TO THE HAZARDS/RISKS NORMALLY ASSOCIATED WITH THE TYPES OF WORK DETAILED ON THIS DRAWING, NOTE THE FOLLOWING CONSTRUCTION.

MAINTENANCE/CLEANING/OPERATION.

DECOMMISSIONING/DEMOLITION.

Notes 1.

THIS DRAWING TO BE READ IN CONJUNCTION WITH 034233_C3110 AND 034233_C3111.

THIS LAYOUT PLAN IS BASED ON: FLETCHER PRIEST ARCHITECTS DRAWINGS RECEIVED ON 19th FEB 2016. THAMES WATER ASSET LOCATION SEARCH SEWER MAP.

EXISTING SEWER INFORMATION IS INDICATIVE ONLY.

THE EXISTING CULVERT INVERT LEVEL REFERS TO AN OLD RECORD AND THE DATUM USED IN THE RECORD MAY NOT BE THE LATEST.

REVISED ISSUE

26.02.16

SECOND ISSUE

16.12.15

MCD NP

INITIAL ISSUE

06.10.15

MCD NP

Date

Drn

Rev Description

INFORMATION Status of drawing

Camden Mill Lower Bristol Road Bath BA2 3DQ UK Architect

Tel:

+44 (0)1225 320600

Fax:

+44 (0)870 787 4148

Email: 034233@burohappold.com Web: www.burohappold.com

FLETCHER PRIEST ARCHITECTS

Project Drg Title

40 1 : 500 Scales@A1

SCALE BEFORE REDUCTION

Job No.

Drawn by Checked by

Drawing No.

Date

Rev

034233 C3112

Ch'd

Appendix H

Revision 00 4 March 2016 Page 15

Design Note Project

TfL Landholdings at Northwood

Subject

Response to LBH Queries, Item 8 of 8

Project no Date

034233 29 February 2016 Revision

Description

Issued by

Date

Response to LBH Query 8 of 8

29/02/2016

Approved (signature)

Introduction

This Technical Note provides the information requested by LBH for item 8 of the above.

Sustainable Drainage System Opportunities

In accordance with the London Plan Policy (5.13), the development’s surface water run-off is to be managed as close as possible to the location where it is generated i.e. at source and it is to be controlled and disposed of in line with the SUDS hierarchy. 

surface water re-uses;



infiltration into the natural ground;



attenuation of surface water in open water features and ponds for slow release;



attenuation of surface water in underground tanks for slow release;



discharge of surface water run-off to a watercourse;



discharge of surface water run-off to a surface water sewer; and



discharge of surface water run-off to a combined sewer.

There are a number of SUDS devices that can be employed but not all are suitable for high density urban developments. Those considered suitable for this development are shown below: Table 2—1: Sustainable Drainage Systems

Green Roofs

Filter trenches*

Permeable surfaces*

Swales

Ponds/basins

Attenuation tanks

Rainwater harvesting

Full Application Outline Application

The London Plan requires the design of surface water runoff management to be carried out following a sustainable drainage hierarchy. Further details on the consideration of the following are requested by the LBH, as part of the assessment of the drainage hierarchy and there are: Green roofs: The reasons why Green Roofs have not been incorporated are primarily for Architectural Reasons and the aesthetics of the development. The design and appearance of the development has been the subject of discussion between the Project Architects and the Planning Officers at Hillingdon Council. These discussions included the potential incorporation of green roof construction in the development. Green Roofs have not been chosen for the following reasons : 1) There is no precedent for green roof construction in this area of Northwood . 2)

The predominant architectural style is to use gable roof construction, this roof form precludes the use of green roofs.

As part of the energy strategy it is proposed to install solar panels on the roofs where appropriate, to improve the energy efficiency of the development.

Green roof construction will increase the massing and bulk of the buildings, the designers have had to reduce the mass of earlier deign to satisfy the planners on this aspect.

Green roof constructions tends to be more expensive that traditional construction and will impact on the viability of the development.

Rainwater Gardens : The open area within the detailed element of the proposed schem provides a child’s play area with play equipment, which fulfils the function of contained square which provides an amenity for residents as well as children to use. The size of the open area has been determined to meet the needs of these users ,any loss of area would severely compromise its use as intended. There are no others area within the detailed element suitable for accommodating a rainwater garden.

Page 2 of 4

Infiltration devices : The geology of the area of Northwood Station is shown as being predominantly London Clay with intrusions to the south of Green Lane of the Lambeth Group, indicated on the Strategic Flood Risk Assessment (Figure 12.1) for Hillingdon to be at the southern end of the site .

Figure 2—1: Extract from London Borough of Hillingdon’s Surface Water Management Plan Fig 12.1

Enquiries made of the British Geological Survey’s records has produced details of a borehole at the Northwood Station site collected in 1880, details are shown below :

Figure 2—2 Extract from British Geological Survey for borehole record at TQ09SE15

Page 3 of 4

Figure 2â&#x20AC;&#x201D;3 Borehole record at TQ09SE15

The drainage strategy took into account the above soil conditions, and concluded that the underlying soils would not be suitable for sustainable drainage systems relying on infiltration devices to dispose of storm water runoff from the development. In the post planning stage of the development site investigations will be required and within this process testing can be carried to test the permeability of the soil, to confirm the drainage design strategy.

Swales/Ponds/Basins: The configuration of the development does not support the use of swales or ponds on site.

Page 4 of 4

Click here to enter text.

Revision 00 4 March 2016

Edward Funnell Buro Happold Limited 17 Newman Street London W1T 1PD UK T: +44 (0)207 927 9700 F: +44 (0)870 787 4145 Email: edward.funnell@burohappold.com