DECEMBER 2018

Lidl GmbH UK

Lidl Mottingham

Drainage Assessment & Surface Water Drainage Strategy

133426-R1(1)-FRA

Lidl GmbH UK – 03rd December 2018

Lidl Mottingham

Drainage Assessment & Surface Water Drainage Strategy

133426-R1(1)

RSK GENERAL NOTES

Project No.: 133426-R1(1)-FRA

Site: Lidl Mottingham

Title: Drainage Assessment & Surface Water Drainage Strategy

Client: Lidl GmbH UK

Date: 03 December 2018

Office: Coventry

Status: Final

Author Tom Stock Technical reviewer Andrew Taylor

Signature

Signature

Date: 03rd December 2018 Date: 03rd December 2018

Project manager Andrew Taylor

Project Director Andrew Taylor

Signature Signature

Date: 03rd December 2018 Date: 03rd December 2018

Issue No Version/Details Date

issued Author

Reviewed by

Approved by

R1(0) Draft 26.10.18 TS APT APT

R1(1) Final 03.12.18 TS APT APT

RSK LDE Ltd (RSK) has prepared this report for the sole use of the client, showing reasonable skill and care, for the intended purposes as stated in the agreement under which this work was completed. The report may not be relied upon by any other party without the express agreement of the client and RSK. No other warranty, expressed or implied, is made as to the professional advice included in this report.

Where any data supplied by the client or from other sources have been used, it has been assumed that the information is correct. No responsibility can be accepted by RSK for inaccuracies in the data supplied by any other party. The conclusions and recommendations in this report are based on the assumption that all relevant information has been supplied by those bodies from whom it was requested.

No part of this report may be copied or duplicated without the express permission of RSK and the party for whom it was prepared.

Where field investigations have been carried out, these have been restricted to a level of detail required to achieve the stated objectives of the work.

This work has been undertaken in accordance with the quality management system of RSK LDE Ltd.

RSK Land & Development Engineering Ltd

Registered office

Spring Lodge • 172 Chester Road • Helsby • Cheshire • WA6 0AR • UK

Registered in England No. 4723837 www.rsk.co.uk

Lidl UK GmbH – 03rd December 2018

Lidl, Mottingham – Drainage Assessment

Ref: 133426-R1(1) Page 1 of 11

1 INTRODUCTION

RSK Land & Development Engineering Ltd were commissioned by the client, Lidl UK GmbH, to provide a

drainage assessment and indicative drainage strategy for redevelopment of the above site located at

Mottingham Road, London.

This drainage assessment has been produced in support of the planning submission for the proposed

demolition of the existing public house and construction of a new purpose built Lidl store, car parking and

soft landscaping.

The purpose of the report is to ensure that flood risk will not increase post-development, by providing a

drainage strategy to manage and dispose of surface water runoff. The drainage strategy must demonstrate

that runoff from the development will be controlled for its lifetime (in this case assumed to be 25 years)

taking account of the vulnerability of its users, without increasing flood risk elsewhere.

This report has been prepared in line with the National Planning Policy Framework (NPPF) (Ref. 1), its

corresponding Planning Practice Guidance (PPG) (Ref. 2), the London Plan (Ref. 3) and the Defra non-statutory

technical standards (Ref. 4).

The comments given in this report and opinions expressed are subject to RSK Group Service Constraints

provided in Appendix A.

Lidl UK GmbH – 03rd December 2018

Lidl, Mottingham – Drainage Assessment

Ref: 133426-R1(1) Page 2 of 11

2 SITE DETAILS AND PROPOSALS

The site is located on south east approach to the Mottingham Road and West Park roundabout, towards

the north of Mottingham. The site is bounded by Mottingham Road to the north and east, commercial

premises to the west and residential occupancy to the south, with site access currently off Mottingham

Road. The site can be located at National Grid Reference 542099, 172885 as shown in Figure 1 below.

The site is approximately 2500m2 in size and was previously occupied by a public house, comprising a car

park, existing building and associated rear garden.

Figure 1: Site Location Plan.

The development proposals for the site are for the demolition of the existing building and associated car

park located on the eastern part of the site, with construction of the new Lidl store spanning across the site

from west to east, constructing a relocated access off Mottingham Road. The proposed store will be 2

storey’s in height in parts, with the sales area and car park on the ground floor, and the warehouse at first

floor level.

The existing topographical survey of the site is included as Appendix B. Proposed site layout drawings are

included within Appendix C.

Lidl UK GmbH – 03rd December 2018

Lidl, Mottingham – Drainage Assessment

Ref: 133426-R1(1) Page 3 of 11

3 SITE CHARACTERISTICS

3.1 Topography

The topographical survey indicates that site levels vary from 39.89m above ordnance datum (AOD) to the

east of the site on the southern site boundary, to 39.08m AOD to the west of the site on the northern site

boundary. The site is relatively flat, but in general, the existing building and car park to the east of the site

are elevated in comparison to the existing garden area to the west. In the existing car park, the site falls

away from an approximate level of 39.75m AOD at the existing building, to levels ranging from 39.21m

AOD and 39.46m AOD at the eastern site boundary, where the site bounds Mottingham road. Adjacent

road levels in Mottingham Road fall from 39.41m AOD in the east down to 39.20m AOD at the roundabout

with Park Lane.

A copy of the topographical survey is included in Appendix B.

3.2 Hydrology

The nearest Main River to the site (the Quaggy River) is approximately 1900m to the north west of the site,

with the nearest area of Flood Zone 3 (defended) also approximately 1900m north west of the site, to the

southern side of the Sidcup Road, immediately north west of Kippington Drive. There are no watercourses

within the site boundary.

3.3 Geology

British Geological Survey (BGS) records indicate that the site is likely to be underlain by the London Clay

Formation – Clay and Silt. No superficial deposits are recorded to be present beneath the site.

3.4 Hydrogeology

Reference to the Environment Agency's (EA’s) online maps indicates that the site is not underlain by any

significant aquifers, based on the presence of impermeable London Clay beneath the site. There are no

nearby BGS borehole records available to indicate possible site groundwater levels.

Lidl UK GmbH – 03rd December 2018

Lidl, Mottingham – Drainage Assessment

Ref: 133426-R1(1) Page 4 of 11

4 SOURCES OF INFORMATION

4.1 Environment Agency

4.1.1 Flood Zone Maps

The EA Flood Zone mapping study for England and Wales is available on their website at

http://maps.environment-agency.gov.uk/

The EA has produced Flood Zone maps for much of England and Wales. The current displayed map shows

the site lies wholly within Flood Zone 1, showing the site is at low risk of flooding from fluvial or tidal

sources.

In December 2013, the EA released an additional form of mapping ‘Risk of Flooding from Rivers and Sea’,

which is available at:

http://watermaps.environment-

agency.gov.uk/wiyby/wiyby.aspx?topic=floodmap#x=357683&y=355134&scale=2

The relevant guidance note from the EA is available online through the following link:

https://www.gov.uk/planning-applications-assessing-flood-risk

4.2 Drainage

4.2.1 Public Sewer

Thames Water sewer records have been obtained and show that there are both foul and surface water

public sewers within Mottingham Road. The existing foul sewer, flowing from east to west is a 300mm

diameter pipe with an invert level of 36.29m AOD recorded within the immediate vicinity of the eastern site

boundary at manhole 1905B. There is no manhole information for the existing surface water sewer within

the immediate vicinity of the site, it is assumed the sewer flows from east to west. The closest manhole with

information recorded is 0902, located within the Mottingham Road and Highcombe Close bellmouth, where

an invert level of 35.367m AOD has been recorded for the 300mm diameter pipe.

4.2.2 Private Drainage

From the topographical survey the current on-site drainage regime consists of the following:

• Combined foul and surface water drainage networks that serve the current building. The first sewer

serves the west of the existing building and flows from south to north, it then flows west to east along

the northern side of the building, before flowing south east. The second sewer serves the southern

side of the building where it then flows north east beneath the building footprint, before flowing from

south to north adjacent to the eastern face of the existing building. These sewers are connected and

combine in a location within close proximity to the north west corner of the building, at an invert level

of 38.24m AOD.

• From the topographical survey there is no evidence of any existing flow controls being installed, nor

any surface water attenuation systems being installed. As such it is assumed that the site in its

current form benefits from an unrestricted combined water discharge into the existing foul water

sewerage system found in Mottingham Road.

Lidl UK GmbH – 03rd December 2018

Lidl, Mottingham – Drainage Assessment

Ref: 133426-R1(1) Page 5 of 11

Sustainable Drainage Systems (SuDS)

NPPF states that Sustainable Drainage Systems (SuDS) should be considered wherever practical. The use

of SuDS is also encouraged by local policy. In accordance with the London Plan, the surface water

drainage strategy should seek to implement a SuDS hierarchy that aspires to achieve reductions in surface

water runoff rates to greenfield rates (Preferred Standard). As a minimum, the proposed surface water

drainage strategy should achieve the Essential Standard set out in the London Plan to reduce runoff to

50% of existing rates if the greenfield rate is not practicable.

4.3 Pre-development situation

The existing site areas are given in Table 5.1 below:

Table 5.1: Existing site land uses

Land use Area (m2) Percentage

Impermeable 1346 53%

Permeable 1194 47%

Total 2540 100%

The ICP method has been used to estimate the greenfield surface water runoff for the site. Calculations are

contained in Appendix D.

Table 5.2: ICP surface water runoff (greenfield) total site

As a developed site with a detailed drainage survey available, it has been possible to construct a drainage

model that reflects the hydraulic performance of the existing drainage network and accurately determine

the existing surface water flows from the site.

Topographical survey data suggests that whilst two existing gullies are present within the existing car park,

they are not strategically placed and therefore do not accommodate significant catchment areas. Blockages

are also likely as the site has been derelict without infrastructure maintenance for several years. It is

therefore assumed the surface water flows arising from the car park are not contained within the site and

instead discharge directly into the existing surface water sewer located in Mottingham road via road gullies.

Return period Peak flow (l/s)

Qbar 0.4

1 in 1 year 0.3

1 in 30 year 0.9

1 in 100 year 1.3

Lidl UK GmbH – 03rd December 2018

Lidl, Mottingham – Drainage Assessment

Ref: 133426-R1(1) Page 6 of 11

Only the catchment for the roof area of the existing building has been included within the hydraulic model.

Further pre-development run-off calculations have been carried out to determine the total existing surface

water flows.

No foul water flows were introduced into the drainage network; therefore, the actual existing rate is slightly

higher than the one shown in this report. Given that the proposed flows from the site are to be based on a

50% reduction of existing flows, this should be considered a conservative approach to the proposed

drainage design.

The existing surface water flows, totaling results from the hydraulic model and further run-off calculations

for the car park are shown in table 5.3 below.

These drainage calculations are shown in Appendix D.

Table 5.3: Existing off-site surface water discharge

4.4 Limiting discharge for design

As shown in Table 5.3 above, the current surface water discharge for the development ranges from 11.3

litres per second for the 2 year event, to 28.9 litres per second for the 100 year event.

The existing surface water sewer located in Mottingham Road that is assumed to flow east to west has no

existing manhole or pipe information. It will be necessary to submit a developer enquiry to Thames Water

to determine capacity and existing sewer information.

It is anticipated that the Local Planning Authority will require the proposed surface water run off rates to be

significantly reduced in accordance with the London Sustainable Drainage Action Plan’s requirement for

Delivering Sustainable Drainage through New Developments via the Planning System, which advises that

“…applications over recent years have included proposals to significantly reduce rainwater discharge.

These reductions are often to greenfield run-off rates but almost always achieve a 50 percent cut in the

sites previous peak run off.”

As such it is proposed that the peak surface water flow from the proposed redeveloped site be restricted to

5.6 litres per second for all storm events up to and including the 100 year event plus 20% climate change

flow.

This represents a reduction in flow of more than 50% when compared to the existing surface water

discharge for the 2 year event. The proposed rate of surface water discharge is significantly less when

compared to the existing 30 year and 100 year events.

Return period Peak flow (l/s)

1 in 2 year 11.3

1 in 30 year 22.2

1 in 100 year 28.9

Lidl UK GmbH – 03rd December 2018

Lidl, Mottingham – Drainage Assessment

Ref: 133426-R1(1) Page 7 of 11

4.5 Post-development situation

The proposed site areas are given in Table 5.4 below:

Table 5.4: Proposed site land uses

Land use Area (m2) Percentage

Impermeable 2540 100%

Permeable 0 0%

Total 2540 100%

The proposed development is approximately 100% impermeable, which would result in an increase in run

off rates when compared to the existing situation.

4.5.1 Offsite discharge options

4.5.2 Infiltration

Infiltration should be considered as the primary option to discharge surface water from the developed site.

The effectiveness of infiltration is completely dependent on the physical conditions at the site. Potential

obstacles include:

• It is understood from the local geology that the site is situated on an area of London Clay. This

stratum is considered impermeable, and as such, infiltration would not be considered suitable.

• Shallow groundwater table - For infiltration drainage devices, Building Regulation approved

document H2 (Ref. 5) states that these “should not be built in ground where the water table reaches

the bottom of the device at any time of the year”. Depth to groundwater beneath the site is

unconfirmed, however, given the location of the site, and the surrounding topography, groundwater

is expected to be a reasonable depth below the site.

• Source Protection Zones – From the Environment Agency records it would appear the site is not

located within a Groundwater Source Protection Zone.

From the information available, infiltration is not considered a viable option as part of the drainage strategy,

although this should be confirmed through site-specific ground investigation and soakage testing.

4.5.3 Discharge to watercourse

Discharging surface water directly to a local watercourse is not considered feasible as there are no suitable

watercourses within the immediate vicinity of the site.

4.5.4 Discharge to sewer

Lidl UK GmbH – 03rd December 2018

Lidl, Mottingham – Drainage Assessment

Ref: 133426-R1(1) Page 8 of 11

The topographical survey indicates that existing flows discharge into an existing Thames Water foul sewer

in Mottingham road. This arrangement would not be accepted post development, separate direct

connections are proposed to the adjacent surface and foul water sewers, subject to discharge approval.

The re-development proposals for this Lidl store do not illustrate a finished floor level at present, nor do

Thames Water records show manhole or pipe size information for the surface water sewer within the

immediate vicinity of the site in Mottingham road. It is assumed that the sewer will be deep enough to

provide a gravity connection point, based on an invert level of 35.367m AOD recorded at manhole 0902,

located within the Mottingham Road and Highcombe Close bellmouth. The proposed strategy contained in

Figure 2 is based on a gravity system. As previously mentioned, a developer inquiry is required to confirm

the invert level of the proposed surface water connection point in Mottingham Road.

The existing 300mm diameter foul sewer, located in Nottingham road is relatively deep and is assumed to

be able to accommodate a gravity system from the development. Based on the assumption that existing

flows from the site convey to the existing foul and surface water sewers, it is assumed capacity will not be

an issue for either sewer.

4.5.5 Storage estimates

To determine the approximate volume of attenuation storage that would be required on the site, the

WinDes 'Quick Storage' calculation has been used. WinDes ‘Quick Storage’ calculations provide a range of

volumes as an approximation of the storage requirement. These volumes can be later revised at detail

design stage by the introduction of specific flow control methods and full network design.

Calculations have been run using a discharge rate of 5.6l/s and an impermeable area of 2540m2. No

allowance is included in the calculations for infiltration and therefore the results illustrate a worst-case

scenario. A 20% increase in rainfall intensity has been included, based on a design life of 25 years.

Calculations can be found in Appendix E.

Table 5.5: Quick Storage estimates

Return period Quick Storage volume (m3)

Minimum Maximum

1 in 30 year 46 68

1 in 100 year 66 95

1 in 100 year + 20% CC 84 118

The maximum storage required on-site to accommodate the 1 in 100 year plus 20% climate change rainfall

event is approximately 118m3.

4.6 Proposed indicative drainage strategy

The proposed SuDS for the site includes the provision of a modular storage and permeable paving system

to be located within the car park, with a peak flow restricted to 5.6 litres per second.

It is proposed that parking spaces 01 to 16 are constructed with permeable paving, to provide water quality

treatment, as well as attenuation volume. Permeable paving will provide approximately 17m3 of storage.

Lidl UK GmbH – 03rd December 2018

Lidl, Mottingham – Drainage Assessment

Ref: 133426-R1(1) Page 9 of 11

The proposed attenuation tank will provide approximately a further 101m3 of storage required to retain the 1

in 100 plus 20% climate change event.

A bypass petrol interceptor is proposed to treat pollutants which arise from car park run-off prior to

discharge.

The SuDS measures are outlined in the Indicative Surface Water Drainage Strategy as attached in Figure

2.

The dimensions, volumes and location of the SuDS features will need to be revised as the masterplan

develops and during the detailed planning stage. Detailed design of individual features is not part of the

scope at this stage. Preliminary design criteria have been based upon guidance given in the CIRIA

publication ‘The SUDS Manual’ (Ref. 6).

In principle, the strategy contains the following features and criteria:

• Figure 2 illustrates a worst-case scenario in terms of the possible area for underground storage.

• Some proposed permeable paving could be incorporated in car parking bays and this is shown in

Figure 2.

The SuDS features have a preliminary design to accommodate the 1 in 100 year plus 20% climate change

event fully underground within the modular storage.

Maintenance of all proposed features would be under the same responsibility as those currently on-site. An

example SuDS maintenance schedule is included within Appendix F of this report, indicating the possible

maintenance of proposed SuDS features.

5 FLOOD MITIGATION MEASURES

Given the location of the site within Flood Zone 1 and the absence of significant overland flow routes

through the site, no further mitigation measures are recommended.

6 CONCLUSIONS AND RECOMMENDATIONS

The proposed development will increase the impermeable area by approximately 1194m2 but the proposed

peak surface water flow rate from the site will be significantly reduced to less than half the current rate of

flow seen for the existing 2 year storm events.

The strategy comprises of some permeable paving and modular storage within the car park of the

proposed store.

The existing lateral connection into the existing off-site foul water drainage network will be abandoned, as

the footprint of the proposed store extends over the existing pipe. A new lateral will be connected to surface

water sewer in Mottingham, with a restricted discharged of 5.6 litres per second. This will ensure that all

runoff is controlled and managed on-site up to the 1 in 100 year plus 20% climate change storm event.

We trust the above is useful, but should you require any additional information, please do not hesitate to

contact the undersigned.

Lidl UK GmbH – 03rd December 2018

Lidl, Mottingham – Drainage Assessment

Ref: 133426-R1(1) Page 10 of 11

APPENDICES Appendix A: Service Constraints

Appendix B: Topographical survey

Appendix C: Proposed site layout plans

Appendix D: Existing site Microdrainage calculations

Appendix E: Proposed Quickstore calculations

Appendix F: SuDS Maintenance Schedule

REFERENCES

1. Communities and Local Government, ‘National Planning Policy Framework’, 2012.

2. Communities and Local Government, ‘Planning Practice Guidance - Flood Risk and Coastal Change, ID 7’, March 2014.

http://planningguidance.planningportal.gov.uk/blog/guidance/flood-risk-and-coastal-change/

3. Mayor of London, ‘The London Plan: Spatial Development Strategy for Greater London – Consolidated

with alterations since 2011’, March 2016.

4. DEFRA, ‘Sustainable Drainage Systems - Non-statutory technical standards for sustainable drainage systems’, March 2015.

5. HM Government (2010 with 2013 amendments), ‘The Building Regulations 2010: Approved Document H - Drainage and Waste Disposal (2002 Edition incorporating 2010 amendments)’.

6. CIRIA, ‘The SUDS Manual – C753’, 2015.

FIGURE 2

Indicative surface water drainage strategy

Drawing Title

Scale

Chkd.

Project Title

Rev. Date Amendment Drawn Appd.

Client

Drawing File

Drawn Date

Orig Size Dimensions

Checked Date Approved Date

0

2 64

Scale 1:200

8

10m

Status

Project No. Originator Unit Site Area Series Number Sheet

Revision

FOR PLANNING

TS Oct 2018 APT Oct 2018 APT Oct 2018

1:200 A1 m P02

133426 RSK C ALL 01 01 01

P01 26.10.18 Preliminary Issue. TS APT APT

P02 03.12.18 Updated to suit revised site layout & client

comments

TS APT APT

APPENDIX A

Service Constraints

1. This report and the Drainage design carried out in connection with the report (together the "Services")

were compiled and carried out by RSK LDE Ltd (RSK) for Lidl UK GmbH (the "client") in accordance with

the terms of a contract between RSK and the "client" dated April 2017. The Services were performed by

RSK with the skill and care ordinarily exercised by a reasonable Civil Engineer at the time the Services

were performed. Further, and in particular, the Services were performed by RSK taking into account the

limits of the scope of works required by the client, the time scale involved and the resources, including

financial and manpower resources, agreed between RSK and the client.

2. Other than that expressly contained in paragraph 1 above, RSK provides no other representation or

warranty whether express or implied, in relation to the Services.

3. Unless otherwise agreed the Services were performed by RSK exclusively for the purposes of the

client. RSK is not aware of any interest of or reliance by any party other than the client in or on the

Services. Unless expressly provided in writing, RSK does not authorise, consent or condone any party

other than the client relying upon the Services. Should this report or any part of this report, or otherwise

details of the Services or any part of the Services be made known to any such party, and such party

relies thereon that party does so wholly at its own and sole risk and RSK disclaims any liability to such

parties. Any such party would be well advised to seek independent advice from a competent

environmental consultant and/or lawyer.

4. It is RSK’s understanding that this report is to be used for the purpose described in the introduction to

the report. That purpose was a significant factor in determining the scope and level of the Services.

Should the purpose for which the report is used, or the proposed use of the site change, this report may

no longer be valid and any further use of or reliance upon the report in those circumstances by the client

without RSK's review and advice shall be at the client's sole and own risk. Should RSK be requested to

review the report after the date hereof, RSK shall be entitled to additional payment at the then existing

rates or such other terms as agreed between RSK and the client.

5. The passage of time may result in changes in site conditions, regulatory or other legal provisions,

technology or economic conditions which could render the report inaccurate or unreliable. The

information and conclusions contained in this report should not be relied upon in the future without the

written advice of RSK. In the absence of such written advice of RSK, reliance on the report in the future

shall be at the client's own and sole risk. Should RSK be requested to review the report in the future, RSK

shall be entitled to additional payment at the then existing rate or such other terms as may be agreed

between RSK and the client.

6. The observations and conclusions described in this report are based solely upon the Services, which

were provided pursuant to the agreement between the client and RSK. RSK has not performed any

observations, investigations, studies or testing not specifically set out or required by the contract between

the client and RSK. RSK is not liable for the existence of any condition, the discovery of which would

require performance of services not otherwise contained in the Services. For the avoidance of doubt,

unless otherwise expressly referred to in the introduction to this report, RSK did not seek to evaluate the

presence on or off the site of asbestos, electromagnetic fields, lead paint, heavy metals, radon gas or

other radioactive or hazardous materials.

7. The Services are based upon RSK's observations of existing physical conditions at the site gained

from a walk-over survey of the site together with RSK's interpretation of information including

documentation, obtained from third parties and from the client on the history and usage of the site. The

Services are also based on information and/or analysis provided by independent testing and information

services or laboratories upon which RSK was reasonably entitled to rely. The Services clearly are limited

by the accuracy of the information, including documentation, reviewed by RSK and the observations

possible at the time of the walk-over survey. Further RSK was not authorised and did not attempt to

independently verify the accuracy or completeness of information, documentation or materials received

from the client or third parties, including laboratories and information services, during the performance of

the Services. RSK is not liable for any inaccurate information or conclusions, the discovery of which

inaccuracies required the doing of any act including the gathering of any information which was not

reasonably available to RSK and including the doing of any independent investigation of the information

provided to RSK save as otherwise provided in the terms of the contract between the client and RSK.

8. The phase II or intrusive environmental site investigation aspects of the Services is a limited sampling

of the site at pre-determined borehole and soil vapour locations based on the operational configuration of

the site. The conclusions given in this report are based on information gathered at the specific test

locations and can only be extrapolated to an undefined limited area around those locations. The extent of

the limited area depends on the soil and groundwater conditions, together with the position of any current

structures and underground facilities and natural and other activities on site. In addition chemical analysis

was carried out for a limited number of parameters [as stipulated in the contract between the client and

RSK] [based on an understanding of the available operational and historical information,] and it should

not be inferred that other chemical species are not present.

9. Any site drawing(s) provided in this report is (are) not meant to be an accurate base plan, but is (are)

used to present the general relative locations of features on, and surrounding, the site.

APPENDIX B

Topographical survey

APPENDIX C

Proposed site layout plans

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7

LIDL PARKING

Standard Parking: 29 Spaces

Disabled Parking: 2 Spaces

Parent & Child Parking: 2 Spaces

Total Parking for Store: 33 Spaces

CYCLE PARKING: 26 Spaces

Electric Car parking/

Charging point

0 10 20 30 40 50m5 15 25 35 45

50m Scale Bar

DESCRIPTIONDATEREV BY

JOB NO. :

DATE : SCALE :

PROJECT :

DRAWING TITLE :

DWG NO. :

DRAWN BY :

REV :

CAD REFERENCE:

THIS DRAWING SHOULD NOT BE SCALED.

IN CASE OF DOUBT OR DISCREPANCIES PLEASE REFER TO ARCHITECT

FOR INSTRUCTIONS.

THIS DRAWING IS COPYRIGHT.

DRAWING STATUS :

04. PRODUCTION INFORMATION

06. TENDER

01. DESIGN

05. BUILDING REGULATIONS

07. CONSTRUCTION

02. DESIGN CONCLUSION 08. FINAL CONSTRUCTION

03. PLANNING

OTHER :

09. SPARE

02. FOR COMMENT01. PRELIMINARY 03. FOR APPROVAL

N:\01 Projects\4974 LIDL

Mottingham\40_Architectural\42_Planning\02_Titled

Drawings\Proposed Site Plan 4974 AL 02 rev 2.dwg

Tel: 029 2055 8900 Fax: 029 2039 9592

4th Floor, Greyfriars House

Greyfriars Road,

Cardiff CF10 3AL

www.boyesrees.co.uk

Registered office. As above Reg No. 295 1683 ( England & Wales )

@

03. PLANNING

03. FOR APPROVAL

PROPOSED DEVELOPMENT FOR

LIDL UK GmbH AT

MOTTINGHAM

PROPOSED SITE PLAN

22.11.2018 1:500 A3

4974 ADT

4974 AL 02 D

clients logo

FOR REVIEW & COMMENT 09.11.18- EC

ADDED SCHEDULE & CYCLE PARKING16.11.18- MJA

ELECTRIC CHARGE LEGEND ADDED20.11.18B SR

SITE BOUNDARY AMENDED

GOODS LIFT UPDATED21.11.18 MJC

GOODS LIFT UPDATED22.11.18 MJD

APPENDIX D

Existing site Microdrainage calculations

ICP SUDS Mean Annual Flood

Input

Return Period (years) 2 Soil 0.300

Area (ha) 0.254 Urban 0.000

SAAR (mm) 620 Region Number Region 6

Results l/s

QBAR Rural 0.4

QBAR Urban 0.4

Q2 years 0.4

Q1 year 0.3

Q30 years 0.9

Q100 years 1.3

RSK Ltd

18 Frogmore Road

Hemel Hempstead

Herts, HP3 9RT

Date 09/10/2018 11:08

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©1982-2010 Micro Drainage Ltd

Existing Network Details for Existing

PN Length

(m)

Fall

(m)

Slope

(1:X)

Area

(ha)

T.E.

(mins)

DWF

(l/s)

k

(mm)

HYD

SECT

DIA

(mm)

1.000 14.527 0.250 58.1 0.006 5.00 0.0 0.600 o 150

1.001 11.760 0.300 39.2 0.007 0.00 0.0 0.600 o 150

1.002 10.680 0.510 20.9 0.001 0.00 0.0 0.600 o 150

2.000 2.625 0.030 87.5 0.010 5.00 0.0 0.600 o 150

2.001 12.618 0.580 21.8 0.002 0.00 0.0 0.600 o 150

2.002 4.000 0.090 44.4 0.002 0.00 0.0 0.600 o 150

1.003 11.960 2.114 5.7 0.002 0.00 0.0 0.600 o 150

Network Results Table

PN US/IL

(m)

Σ Area

(ha)

Σ DWF

(l/s)

Vel

(m/s)

Cap

(l/s)

1.000 39.300 0.006 0.0 1.32 23.4

1.001 39.050 0.013 0.0 1.61 28.5

1.002 38.750 0.014 0.0 2.21 39.1

2.000 38.940 0.010 0.0 1.08 19.0

2.001 38.910 0.012 0.0 2.17 38.3

2.002 38.330 0.014 0.0 1.51 26.7

1.003 38.240 0.030 0.0 4.27 75.4

RSK Ltd

18 Frogmore Road

Hemel Hempstead

Herts, HP3 9RT

Date 10/10/2018 16:38

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©1982-2010 Micro Drainage Ltd

Manhole Schedules for Existing

MH

Name

MH

CL (m)

MH

Depth

(m)

MH

Diam.,L*W

(mm)

PN

Pipe Out

Invert

Level (m)

Diameter

(mm)

PN

Pipes In

Invert

Level (m)

Diameter

(mm)

Backdrop

(mm)

1 39.900 0.600 1200 1.000 39.300 150

2 39.810 0.760 1200 1.001 39.050 150 1.000 39.050 150

3 39.680 0.930 1200 1.002 38.750 150 1.001 38.750 150

3 39.770 0.830 1200 2.000 38.940 150

4 39.730 0.820 1200 2.001 38.910 150 2.000 38.910 150

5 39.570 1.240 1200 2.002 38.330 150 2.001 38.330 150

7 39.560 1.320 1200 1.003 38.240 150 1.002 38.240 150

2.002 38.240 150

39.180 3.054 0 OUTFALL 1.003 36.126 150

RSK Ltd

18 Frogmore Road

Hemel Hempstead

Herts, HP3 9RT

Date 10/10/2018 16:38

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©1982-2010 Micro Drainage Ltd

PIPELINE SCHEDULES for Existing

Upstream Manhole

PN Hyd

Sect

Diam

(mm)

MH

Name

C.Level

(m)

I.Level

(m)

D.Depth

(m)

MH DIAM., L*W

(mm)

1.000 o 150 1 39.900 39.300 0.450 1200

1.001 o 150 2 39.810 39.050 0.610 1200

1.002 o 150 3 39.680 38.750 0.780 1200

2.000 o 150 3 39.770 38.940 0.680 1200

2.001 o 150 4 39.730 38.910 0.670 1200

2.002 o 150 5 39.570 38.330 1.090 1200

1.003 o 150 7 39.560 38.240 1.170 1200

Downstream Manhole

PN Length

(m)

Slope

(1:X)

MH

Name

C.Level

(m)

I.Level

(m)

D.Depth

(m)

MH DIAM., L*W

(mm)

1.000 14.527 58.1 2 39.810 39.050 0.610 1200

1.001 11.760 39.2 3 39.680 38.750 0.780 1200

1.002 10.680 20.9 7 39.560 38.240 1.170 1200

2.000 2.625 87.5 4 39.730 38.910 0.670 1200

2.001 12.618 21.8 5 39.570 38.330 1.090 1200

2.002 4.000 44.4 7 39.560 38.240 1.170 1200

1.003 11.960 5.7 39.180 36.126 2.904 0

Free Flowing Outfall Details for Existing

Outfall

Pipe Number

Outfall

Name

C. Level

(m)

I. Level

(m)

Min

I. Level

(m)

D,L

(mm)

W

(mm)

1.003 39.180 36.126 0.000 0 0

Simulation Criteria for Existing

Volumetric Runoff Coeff 0.750 Foul Sewage per hectare (l/s) 0.000

PIMP (% impervious) 100 Additional Flow - % of Total Flow 0.000

Areal Reduction Factor 1.000 MADD Factor * 10m³/ha Storage 2.000

Hot Start (mins) 0 Inlet Coeffiecient 0.800

Hot Start Level (mm) 0 Run Time (mins) 60

Manhole Headloss Coeff (Global) 0.500 Output Interval (mins) 1

Number of Input Hydrographs 0 Number of Offline Controls 0

Number of Online Controls 0 Number of Storage Structures 0

RSK Ltd

18 Frogmore Road

Hemel Hempstead

Herts, HP3 9RT

Date 10/10/2018 16:38

File 133426.MDX

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©1982-2010 Micro Drainage Ltd

Simulation Criteria for Existing

Number of Time/Area Diagrams 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) 20.000 Storm Duration (mins) 30

Ratio R 0.442

RSK Ltd

18 Frogmore Road

Hemel Hempstead

Herts, HP3 9RT

Date 10/10/2018 16:38

File 133426.MDX

Micro Drainage

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©1982-2010 Micro Drainage Ltd

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

Existing

Margin for Flood Risk Warning (mm) 450.0

Analysis Timestep 2.5 Second Increment (Extended)

DTS Status OFF

DVD Status ON

Inertia Status OFF

Profile(s) Summer and Winter

Duration(s) (mins) 15, 30, 60, 120, 240, 360, 480, 960, 1440

Return Period(s) (years) 2, 30, 100

Climate Change (%) 0, 0, 0

PN

Storm

Return

Period

Climate

Change

First X

Surcharge

First Y

Flood

First Z

Overflow

O/F

Act.

Lvl

Exc.

1.000 15 Winter 2 0%

1.001 15 Winter 2 0%

1.002 15 Winter 2 0%

2.000 15 Winter 2 0%

2.001 15 Winter 2 0%

2.002 15 Winter 2 0%

1.003 15 Winter 2 0%

PN

US/MH

Name

Water

Level

(m)

Surch'ed

Depth (m)

Flooded

Volume

(m³)

Flow /

Cap.

O'flow

(l/s)

Pipe

Flow

(l/s)

Status

1.000 1 39.322 -0.128 0.000 0.05 0.0 1.1 OK

1.001 2 39.080 -0.120 0.000 0.09 0.0 2.2 OK

1.002 3 38.776 -0.124 0.000 0.07 0.0 2.4 OK

2.000 3 38.982 -0.108 0.000 0.17 0.0 1.8 OK

2.001 4 38.934 -0.126 0.000 0.06 0.0 2.2 OK

2.002 5 38.366 -0.114 0.000 0.13 0.0 2.5 OK

1.003 7 38.267 -0.123 0.000 0.08 0.0 5.2 OK

RSK Ltd

18 Frogmore Road

Hemel Hempstead

Herts, HP3 9RT

Date 10/10/2018 16:38

File 133426.MDX

Micro Drainage

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©1982-2010 Micro Drainage Ltd

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

for Existing

Margin for Flood Risk Warning (mm) 450.0

Analysis Timestep 2.5 Second Increment (Extended)

DTS Status OFF

DVD Status ON

Inertia Status OFF

Profile(s) Summer and Winter

Duration(s) (mins) 15, 30, 60, 120, 240, 360, 480, 960, 1440

Return Period(s) (years) 2, 30, 100

Climate Change (%) 0, 0, 0

PN

Storm

Return

Period

Climate

Change

First X

Surcharge

First Y

Flood

First Z

Overflow

O/F

Act.

Lvl

Exc.

1.000 15 Winter 30 0%

1.001 15 Winter 30 0%

1.002 15 Winter 30 0%

2.000 15 Winter 30 0%

2.001 15 Winter 30 0%

2.002 15 Winter 30 0%

1.003 15 Winter 30 0%

PN

US/MH

Name

Water

Level

(m)

Surch'ed

Depth (m)

Flooded

Volume

(m³)

Flow /

Cap.

O'flow

(l/s)

Pipe

Flow

(l/s)

Status

1.000 1 39.332 -0.118 0.000 0.10 0.0 2.1 OK

1.001 2 39.094 -0.106 0.000 0.18 0.0 4.7 OK

1.002 3 38.788 -0.112 0.000 0.14 0.0 5.1 OK

2.000 3 38.999 -0.091 0.000 0.32 0.0 3.5 OK

2.001 4 38.945 -0.115 0.000 0.12 0.0 4.2 OK

2.002 5 38.383 -0.097 0.000 0.26 0.0 4.9 OK

1.003 7 38.280 -0.110 0.000 0.16 0.0 10.6 OK

RSK Ltd

18 Frogmore Road

Hemel Hempstead

Herts, HP3 9RT

Date 10/10/2018 16:38

File 133426.MDX

Micro Drainage

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©1982-2010 Micro Drainage Ltd

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

for Existing

Margin for Flood Risk Warning (mm) 450.0

Analysis Timestep 2.5 Second Increment (Extended)

DTS Status OFF

DVD Status ON

Inertia Status OFF

Profile(s) Summer and Winter

Duration(s) (mins) 15, 30, 60, 120, 240, 360, 480, 960, 1440

Return Period(s) (years) 2, 30, 100

Climate Change (%) 0, 0, 0

PN

Storm

Return

Period

Climate

Change

First X

Surcharge

First Y

Flood

First Z

Overflow

O/F

Act.

Lvl

Exc.

1.000 15 Winter 100 0%

1.001 15 Winter 100 0%

1.002 15 Winter 100 0%

2.000 15 Winter 100 0%

2.001 15 Winter 100 0%

2.002 15 Winter 100 0%

1.003 15 Winter 100 0%

PN

US/MH

Name

Water

Level

(m)

Surch'ed

Depth (m)

Flooded

Volume

(m³)

Flow /

Cap.

O'flow

(l/s)

Pipe

Flow

(l/s)

Status

1.000 1 39.336 -0.114 0.000 0.13 0.0 2.7 OK

1.001 2 39.100 -0.100 0.000 0.24 0.0 6.1 OK

1.002 3 38.794 -0.106 0.000 0.19 0.0 6.6 OK

2.000 3 39.008 -0.082 0.000 0.42 0.0 4.6 OK

2.001 4 38.950 -0.110 0.000 0.16 0.0 5.5 OK

2.002 5 38.391 -0.089 0.000 0.34 0.0 6.4 OK

1.003 7 38.286 -0.104 0.000 0.20 0.0 13.8 OK

RSK Ltd

18 Frogmore Road

Hemel Hempstead

Herts, HP3 9RT

Date 10/10/2018 16:38

File 133426.MDX

Micro Drainage

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©1982-2010 Micro Drainage Ltd

TeleconFile NotesMeeting NotesMemorandumCalculations

withreretoChecked by

Job No.:

Date:

Author/Calc by:

PROJECT NAME:

SUBJECT:

Page ofInternal Admin SheetIssue 1

APPENDIX E

Proposed Quickstore calculations

Windes quick storage estimate – Proposed discharge rate 5.6 litres per second Quickstore variables

1 in 30 year rainfall

1 in 100 year rainfall

1 in 100 year + 20% flow rainfall

APPENDIX F

SuDS Maintenance Schedule

The following section describes the required maintenance for each feature in turn, based on information outlined in CIRIA C697 The SuDS Manual. The SUDS maintenance requirements listed below should be reviewed after the first 5 years, with a view to agreeing a new regime for the ongoing maintenance.

Notwithstanding the routine inspections and maintenance requirements, after severe storm events all features shall be inspected to clear debris and repair damaged structures or features. Records of the maintenance carried out shall be prepared by those responsible for ownership.

Permeable Paving

Maintenance schedule

Required action Typical frequency

Regular maintenance Brushing and vacuuming (standard cosmetic sweep over whole surface)

Once a year, after autumn leaf fall, or reduced frequency as required, based on site-specific observations of clogging or manufacturer’s recommendations – pay particular attention to areas where water runs onto pervious surface from adjacent impermeable areas as this area is most likely to collect the most sediment

Occasional maintenance

Stabilise and mow contributing and adjacent areas

As required

Removal of weeds or management using glyphospate applied directly into the weeds by an applicator rather than spraying

As required – once per year on less frequently used pavements

Remedial Actions

Remediate any landscaping which, through vegetation maintenance or soil slip, has been raised to within 50mm of the level of the paving

As required

Remedial work to any depressions, rutting and cracked or broken blocks considered detrimental to the structural performance or a hazard to users, and replace lost jointing material.

As required

Rehabilitation of surface and upper substructure by remedial sweeping.

Every 10 to 15 years or as required (if infiltration performance is reduced due to significant clogging)

Monitoring

Initial inspection Monthly for three months after installation

Inspect for evidence of poor operation and/or weed growth – if required, take remedial action

Three monthly 48h after large storms in first six months

Inspect silt accumulation rates and establish appropriate brushing frequencies

Annually

Monitor inspection chambers Annually

Modular Storage

Maintenance schedule Required action Typical frequency

Regular maintenance Inspect and identify any areas that are not operating correctly. If required, take remedial action

Monthly for 3 months, the annually

Remove debris from the catchment surface (where it may cause risks to performance)

Monthly

For systems where rainfall infiltrates into the tank from above, check surface of filter for blockage by sediment, algae or other matter; remove and replace surface infiltration medium as necessary.

Annually

Remove sediment from pre-treatment structures and/or internal forebays

Annually, or as required

Remedial actions Repair/rehabilitate inlets, outlet, overflows and vents As required

Monitoring Inspect/check all inlets, outlets, vents and overflows to ensure that they are in good condition and operating as designed

Annually

Survery inside of tank for sediment build-up and remove if necessary

Every 5 years or as required