surface drainage strategy

2 June 2017

SURFACE DRAINAGE STRATEGY

Ling Hall Landfill - PV Project

RE

PO

RT

Report Number 173593.500.A0

Distribution:

REG Ling Hall Solar Ltd - 1 pdf

Golder Associates (UK) Ltd

Submitted to:

REG Ling Hall Solar Ltd Telegraph House, Calenick Street, Truro, Cornwall, TR1 2SF

LING HALL LANDFILL - SURFACE DRAINAGE STRATEGY

2 June 2017 Report No. 173593.500.A0 i

Table of Contents

1.0 INTRODUCTION ........................................................................................................................................................ 1

2.0 SITE HYDROLOGICAL SETTING ............................................................................................................................. 1

2.1 Consented development details.................................................................................................................... 1

3.0 REVIEW OF FLOOD RISK ASSESSMENT (FRA) .................................................................................................... 1

4.0 REVIEW OF CURRENT AND CONSENTED DEVELOPMENT SURFACE WATER RUNOFF RATES AND

DISCHARGE RATES................................................................................................................................................. 2

4.1 Updated climate change allowances ............................................................................................................ 2

4.2 Existing surface water drainage scheme ...................................................................................................... 2

4.3 Surface water calculations and runoff volume increase ................................................................................ 3

5.0 CONCEPTUAL SURFACE DRAINAGE STRATEGY................................................................................................ 3

5.1 Design principles .......................................................................................................................................... 3

5.2 Design .......................................................................................................................................................... 4

5.2.1 Capacity check of current surface drainage scheme (consented for the landfill) .................................... 4

6.0 CONSTRUCTION RECOMMENDATIONS ................................................................................................................ 5

6.1 Maintenance ................................................................................................................................................. 5

7.0 CONCLUSION ........................................................................................................................................................... 6

TABLES

Table 1: Surface water runoff volume calculations (1% AEP + 20% climate change allowance) ........................................ 3

Table 2: Channel capacity check ........................................................................................................................................ 5

FIGURES

Figure 1: EA climate change allowances (Feb, 2016) ......................................................................................................... 2

APPENDICES

APPENDIX A SLR Consulting - Landfill surface water management plan

APPENDIX B Surface water calculation sheets

APPENDIX C BGS - SuDS report

APPENDIX D Drawings


2 June 2017 Report No. 173593.500.A0 1

1.0 INTRODUCTION

Golder Associates have been commissioned by REG Ling Hall Solar Ltd (REG) to develop a surface water

drainage strategy (SDS) for the consented photovoltaics (PV) development on a restored landfill. This report

details a Site specific SDS to discharge Condition 14 attached to planning permission RBC/14CM029 for a

frame mounted solar PV (panels) scheme with associated infrastructure (‘the consented development’) at Ling

Hall Landfill, Coalpit Lane, Rugby, CV23 9HH (‘the Site’). Condition 14 requires the following:

The development hereby permitted shall not be commenced until a suitable surface drainage strategy has

been submitted to and approved in writing by the County Planning Authority. Once approved, the strategy shall

be implemented in full prior the development's first use and maintained for the duration of the development’s

use.

The proposed methodology for our approach will include the following:

Review of the flood risk;

Review of current and consented development surface water runoff rates and discharge rates; and

Conceptual design/plan for the SDS;

2.0 SITE HYDROLOGICAL SETTING

The Site is located adjacent to Lawford Heath Industrial Estate, approximately 5 km west of Rugby. The Site

is accessed from Coalpit Lane, Lawford Heath, CV23 9HH. The nearest watercourse is a small stream located

approximately 700 m to the south east of the Site which discharges to the River Avon, the floodplain for which

does not encroach upon the Site.

The Site lies in an area of typically low relief and shallow surface gradients. Historically the Site was used as

an airfield and more recently as a sand and gravel quarry. Sand and gravel extraction has now ceased and

the Site is being progressively restored with a landfill. The area is characterised by an absence of surface

water features and reflects the presence of sand and gravel locally which readily promotes infiltration to

groundwater.

2.1 Consented development details

The consented development is on a restored landfill, on which fixed arrays of solar panels, inverter

transformers, two substations and fencing will be installed to provide delivery of power supply to the grid. The

foundation for each of the solar panels will be on raised concrete blocks 3.3 m long by 0.6 m wide by 0.36 m

high, constructed at ground level. Grassland will be retained between the panel foundation blocks.

3.0 REVIEW OF FLOOD RISK ASSESSMENT (FRA)

A review of the FRA (Ref: 13514970484.506/A.0 - Golder Associates UK Ltd, July 2014) highlights the

following key points in relation to this SDS:

The Site is shown on published Environment Agency maps to lie in Zone 1, (<0.1% annual probability of

fluvial flooding);

No evidence of historical groundwater flooding within the Site;

No Sewerage at the Site, so no foul water flooding; and

The changes to the surface water runoff regime due to the consented development on Site will require

management and any (minor) increase in volume of runoff during storm events will require attenuation

prior to controlled discharge to the environment to ensure no detriment to the existing drainage.


2 June 2017 Report No. 173593.500.A0 2

4.0 REVIEW OF CURRENT AND CONSENTED DEVELOPMENT SURFACE WATER RUNOFF RATES AND DISCHARGE RATES

The PV development has the potential to alter the rate and volume of surface water entering the existing

drainage system.

Rainfall will flow freely from the solar panels onto the ground or foundations beneath and therefore the panels

themselves will not directly affect the existing hydrological conditions. Finished ground levels across the Site

will be comparable to existing ground levels, however the raised solar panel foundation blocks have the

potential to alter flow paths immediately around the blocks.

The increase in impermeable ground surface cover due to solar panel foundation blocks and new access

tracks will require surface water management planning to ensure there will be no detrimental change to surface

water flood risk from the re-development. The increase in surface water runoff associated to any change to

ground cover can be estimated and attenuation offered on Site to manage post-development runoff volumes

and rates to those of the pre-development scenario. In planning terms (under the National Planning Policy

Framework, NPPF) the Site post-restoration may be considered to be ‘green field’. However, the Site retains

the physical characteristics of a capped landfill is not a green field Site in terms of surface water management.

As such, there is no requirement to manage discharge to a Greenfield rate.

4.1 Updated climate change allowances

The NPPF sets out how the planning system should provide resilience to the impacts of climate change.

Updated Environment Agency (EA) advice updates previous climate change allowances to support NPPF

(February 2016). The updated rainfall intensity in line with the new guidance are presented in Figure 1.

Figure 1: EA climate change allowances (Feb, 2016)

The design life of the project is expected to be 25 years. To understand the range of potential impacts from

climate chance, it is recommended that the full range of rainfall intensities are assessed. This means for this

project, the 1% AEP, plus an allowance of climate change (both 10% and 20%) rainfall intensities will be

explored.

4.2 Existing surface water drainage scheme

Golder understands that the consented landfill restoration profile has/will have a locally elevated profile and is

completed with an engineered low permeability capping system in accordance with best practice.

The landform will therefore readily shed incident rainfall. The landfill is currently active and surface water

runoff is managed using a network of informal drains, ditches and ponds. It is understood that a previous

discharge point to the west of the Site is no longer used.


2 June 2017 Report No. 173593.500.A0 3

As part of the landfill closure strategy, a consented surface water management scheme has been developed

by SLR consulting (2017). It is our intention to review this scheme in this report, and to test its functionality

against the PV development. This report is available for reference in Appendix A.

4.3 Surface water calculations and runoff volume increase

As the Site is a re-development and not a green field Site, there is no requirement to manage discharge to a

Greenfield rate (2.6 l/s/ha).

The pre development Site runoff coefficient is estimated as 60% (National Coal Board guidance); and

The estimated post-development runoff coefficient is 60.3% which is slightly greater due to the presence

of the solar panel foundation blocks.

Table 1: Surface water runoff volume calculations (1% AEP + 20% climate change allowance)

The maximum total increase in surface water runoff volume, for all the areas due to the addition of PV concrete

footings is 72 m3.

Surface water calculation sheets are provided in Appendix B.

5.0 CONCEPTUAL SURFACE DRAINAGE STRATEGY

5.1 Design principles

Containing or infiltrating water directly on the landfill area of the Site is not an option due to the underlying

engineered capping. In order to manage the slight increase in surface water runoff and ensure the

development does not negatively impact areas off Site, the currently consented perimeter infiltration drains

can be utilised and will not need to be enlarged.

A BGS SuDS report that details the surrounding underlying geology is provided in Appendix C. The report

suggests that the subsurface is likely suitable for free-draining infiltration SuDS. Infiltration areas will be away

from the engineered capping (locations of infiltration areas to be confirmed following test pitting (BRE 365) to

confirm subsurface conditions during the construction period).

Industry standard (CIRIA) surface water management guidance, promotes the adoption of SuDS to manage,

attenuate and treat surface water runoff before discharging into the water environment. There are four main

categories of SuDS which are referred to as the ‘four pillars of SuDS design’ as depicted in CIRIA Report

C753. It is proposed that a SuDS strategy is adopted for this Site as appropriate to satisfy the discharge of

conditions.

Area ID

Pre-development extent (m2)

Total PV cells Concrete footing

area (m2) Maximum Increase in

runoff volume (m3)

PV1 150 600 297 588 20

PV2 95 200 187 370 12

PV3 63 000 126 249 8

PV4 108 800 485 960 32

Totals 417 600 1095 2168 72


2 June 2017 Report No. 173593.500.A0 4

It is generally accepted that the implementation of SuDS as opposed to conventional drainage systems,

provides benefits by:

Reducing peak flows to watercourses or sewers and the risk of flooding downstream;

Reducing the volumes and frequency of water flowing directly to watercourses or sewers from developed

sites;

Improving water quality over conventional surface water sewers by removing pollutants from diffuse

pollutant sources; and

Replicating natural drainage patterns, including the recharge of groundwater so that base flows are

maintained.

5.2 Design

Golder estimates that the increase in surface water runoff due to the entire consented development (equivalent

to a volume of 72 m³) for all events up to and including the 1% Annual Exceedance Probability (AEP) plus 20%

climate change rainfall event can be attenuated on Site or within the existing landfill surface water management

scheme.

The approved restoration profile and drainage scheme is shown in Appendix A (SLR, 2017). It is proposed

that the open surface water swales are continued to be used to convey, under gravity, runoff shed from the

restoration slopes to a number of perimeter infiltration basins/ponds.

The proposed SDS for the Site consists of the following four key PV areas depicted in Drawing 1

(1001LH-0001). Appendix D:

1) Additional surface water storage requirements for the northern development (PV1) area will be provided

within the existing surface water attenuation pond (Pond E).


within the existing surface water attenuation pond (Pond A).


within the existing surface water attenuation pond (existing wetland).


within the existing surface water attenuation pond (Pond B).

5.2.1 Capacity check of current surface drainage scheme (consented for the landfill)

The landfill open channels’ carrying capacity have been specified in SLR’s report, 2017. A capacity check has

been completed to ensure that the increase in runoff from the PV development can be accommodated for by

adopting the current scheme.

The changes between the two design parameters are:

The currently consented SDS (SLR, 2017) is based on 1% AEP + 40% allowance for climate change

rainfall is adopted, and assumes a runoff co-efficient of 60%.

For the purposes of this report the 1% AEP + 20% allowance for climate change rainfall is required as

the PV design life is 25 years. A slightly elevated runoff co-efficient of 60.3% is used here to account for

the concrete foundations of the PV cells.


2 June 2017 Report No. 173593.500.A0 5

Table 2: Channel capacity check

Area ID Channel ID Consented Channel/swale

Capacity (m3/s) (SLR, 2017)

PV development Peak flow

to same channel (m3/s)

Capacity check

PV1 To Pond E 1.04 0.84 OK

PV2 To Pond A 3.63 2.22 OK

PV3 To existing wetland (Pond C)

1.55 1.26 OK

PV4 Pond B 2.01 1.8 OK

Table 2 illustrates that the currently consented channels have adequate capacity to convey the slightly

increased runoff (when compared to pre-development) as the consented landfill design has been designed

to the 1% AEP + 40% allowance for climate change rainfall.

Sufficient storage capacity for the anticipated increase in impermeable surfacing during the 1% AEP plus 20%

allowance for climate change rainfall event is available. It is therefore concluded, there will be no increase in

surface water flood risk to the currently consented off-site surface water drainage network as a result of the

consented PV development.

6.0 CONSTRUCTION RECOMMENDATIONS

Drawing 1 (SLR, Appendix 1) and Drawing 1 (Golder, 1001LH-0001, Appendix D) detail the type of swale that

is currently consented as part of landfill restoration. The grassland and shallow slope between the consented

solar panels and perimeter infiltration drains will act as a filter strip which will also likely reduce Total

Suspended Sediments (TSS) in the surface water runoff. Nevertheless, to manage the potential increase in

TSS during construction, temporary silt fences will be installed around the perimeter of the landfill, minimising

the risk of clogging the perimeter infiltration drains.

Gravel strips 300 mm wide will be constructed around the concrete foundation blocks to minimise the potential

development of concentrated flow paths and increased erosion. In addition, grass around the solar panels will

be kept as long as is practicable, which will reduce the velocity of surface water and therefore lessen the

potential for erosion.

6.1 Maintenance

During the design life, REG will be responsible for maintaining the infiltration drains. Routine inspection of the

perimeter drain system, checking for blockages or failure, will be undertaken annually and following any

significant rainfall event or observed surface water flooding. Should any issues arise, REG will investigate the

cause and implement remedial measures, such as cleaning and removing silt, as soon as practicable.

The grass in channels/swales should ideally retain grass lengths of 75 – 150 mm. On cessation of the

operation of the development, the Site will be returned to grassland/meadow. The drainage system will then

be managed by Veolia (or the landowner).


2 June 2017 Report No. 173593.500.A0 6

7.0 CONCLUSION

This report provides the necessary information to address the required additional detail as noted in

Condition 14. It has been demonstrated that there is sufficient storage capacity for the anticipated increase in

impermeable surfacing during the 1% AEP plus 20% allowance for climate change rainfall event for the PV

development. It is therefore concluded, there will be no increase in surface water flood risk to the currently

consented off-site surface water drainage network as a result of the consented PV development.

References

CIRIA Report C753 SUDS manual.

Ling Hall Landfill; Surface Water Management Plan. SLR, 2017.

DEFRA Non-statutory technical standards for SUDS.


2 June 2017 Report No. 173593.500.A0

Report Signature Page

GOLDER ASSOCIATES (UK) LTD

Matt Goode Freddy Brookes

Senior Hydrologist Project Manager

MG-EA/FB/kc

Company Registered in England No.1125149.

At Attenborough House, Browns Lane Business Park, Stanton-on-the-Wolds, Nottinghamshire NG12 5BL

VAT No. 209 0084 92

Golder, Golder Associates and the GA globe design are trademarks of Golder Associates Corporation.


2 June 2017 Report No. 173593.500.A0

APPENDIX A SLR Consulting - Landfill surface water management plan

Ling Hall Landfill

Coalpit Lane, Wolston, Rugby, CV23 9HH

Surface Water Management Plan

SLR Ref: 405.00156.00192 Version No: 2

April 2017 .Version

Veolia i 428.00156.00192 Ling Hall: Surface Water Management Plan April 2017

SLR

1.0 INTRODUCTION .......................................................................................................... 1 1.1 Context and Background ................................................................................. 1 1.2 Report Structure ............................................................................................... 1 1.3 Best Practice Design Guidance ....................................................................... 2

2.0 DESIGN PRINCIPLES ................................................................................................. 3 2.1 Sustainable (urban) Drainage Systems (SuDS) .............................................. 3 2.2 SWMP Design Principals: Water Quality ........................................................ 4 2.3 SWMP Design Principals: Design Storm Event .............................................. 4 2.4 SWMP Design Principals: Perimeter Swale Sizing ......................................... 6 2.5 SWMP Design Principals: Perimeter Swale Design ........................................ 7 2.6 SWMP Design Principals: Infiltration Rates and Basins ................................ 9

3.0 APPROVED RESTORATION SURFACE WATER MANAGEMENT SYSTEM .......... 11 3.1 Infiltration Pond Details .................................................................................. 11 3.2 Hydraulic Performance ................................................................................... 11

4.0 POTENTIAL MAINTENANCE REQUIREMENTS ...................................................... 13 4.1 Potential Maintenance Schedule – Swales .................................................... 13 4.2 Potential Maintenance Schedule – Infiltration Systems & Soakaways ....... 13

5.0 CONCLUSIONS ......................................................................................................... 15 6.0 CLOSURE .................................................................................................................. 16

TABLES

Table 3-1 Approved Restoration: Infiltration Pond Details ............................................ 11 Table 3-2 SuDS Site Control: Hydraulic Modelling Summary ........................................ 12

FIGURES Figure 1 Four Pillars of SuDS (after CIRIA Report C753) ................................................ 3 Figure 2 SuDS Management Train ..................................................................................... 3 Figure 3 Schematic Swale Design ..................................................................................... 7 Figure 4 Typical Stone Check Dam Arrangement ............................................................. 8

DRAWINGS

Drawing No.1 Approved Restoration – Proposed Layout

APPENDICES Appendix A Swale / Ditch Outline Design Calculations and Minimum Required Geometry Appendix B Approved MicroDrainage Pond Modelling Extracts

Veolia 1 428.00156.00192 Ling Hall: Surface Water Management Plan April 2017

SLR

1.0 INTRODUCTION

1.1 Context and Background

SLR Consulting Limited (SLR) has been appointed by Veolia to prepare a revised surface water management plan (SWMP) for Ling Hall Landfill, Rugby, Warwickshire.

This SWMP has been informed by a site walkover survey and has been prepared in consultation with Veolia. In addition a review of groundwater levels at site has been undertaken to ensure that the proposed surface water management elements are located above the local groundwater level. The site Hydrogeological Risk Assessment (HRA) should reflect the surface water scheme at site as it is developed and it is expected the routine site HRA review would incorporate the surface water management measures developed at site.

The site lies in an area of typically low relief and shallow surface gradients. Historically the site was used as an airfield and more recently was developed as a sand and gravel quarry. Sand and gravel extraction has now ceased and the site is being progressively restored with a containment landfill.

The area is characterised by an absence of surface water features and reflects the presence of sand and gravel locally which readily promotes surface water infiltration and groundwater recharge.

The consented landfill restoration profile has a locally elevated profile and is completed with an engineered low permeability capping system in accordance with best practice. The landform will therefore readily shed incident rainfall.

The landfill is currently active and surface water runoff is managed using a network of informal drains, ditches and ponds. It is understood that a previous discharge point to the west of the site was licensed to Ennstone sand and gravel, who have previously worked the sand and gravel deposits at site; it is understood the discharge consent licence has been surrendered. This discharge route is no longer used.

The SWMP therefore has been prepared to assess options for the management and control of surface water shed from site. It assesses the likely volumes of surface water runoff that might be shed from the fully restored and permitted site.

1.2 Report Structure

This report is structured as follows:

• Section 2 presents the design principles used in the assessment; • Section 3 details the proposed surface water management system; • Section 4 discusses best practice construction advice; and • Section 5 provides the report conclusions.


SLR

1.3 Best Practice Design Guidance

This SWMP has been prepared taking cognisance (where appropriate) of the following key policy guidance:

• CIRIA (2015) The SuDS Manual, Report C753, November 2015; • CIRIA (2004) Development and Flood Risk – Guidance for the Construction Industry,

Report C624; • CIRIA and National SuDS Working Group (2004) Interim Code of Practice for

Sustainable Drainage Systems, Report C704; • Environment Agency (2016) Flood Risk Assessments: Climate Change Allowances,

February 2016; • Environment Agency (2013) Rainfall Runoff Management for Developments. Report –

SC030219, October 2013; • National Coal Board (1982) Technical Management of Water in the Coal Mining Industry;

and • Environment Agency (2016) Sizing of Surface Water Management Systems at Landfill

Sites, February 2016 – Draft Guidance.


SLR

2.0 DESIGN PRINCIPLES

2.1 Sustainable (urban) Drainage Systems (SuDS)

Industry standard surface water management guidance, promotes the adoption of SuDS to manage, attenuate and treat surface water runoff before discharging into the water environment.

There are four main categories of SuDS which are referred to as the ‘four pillars of SuDS design’ as depicted in Figure 1.

Figure 1 Four Pillars of SuDS (after CIRIA Report C753)

The SuDS Manual identifies a hierarchy of SuDS for managing runoff, which is commonly referred to as a ‘management train’ as depicted in Figure 2.

Figure 2 SuDS Management Train

• Prevention – the use of good site design and housekeeping measures on individual sites to prevent runoff and pollution (e.g. minimise areas of hard standing);

• Source Control – control of runoff at or very near its source (such as the use of rainwater re-use, permeable paving and green roofs);

• Conveyance – routing of collected runoff from ‘Source Control’ features to ‘Site Control’ or ‘Regional Control’ measures;


SLR

• Site Control – management of water from several sub-catchments to one / several soakaways or attenuation ponds for the whole site; and

• Regional Control – management of runoff from several sites, typically in a retention pond or wetland.

It is generally accepted that the implementation of SuDS as opposed to conventional drainage systems, provides several benefits by:

• reducing peak flows to watercourses or sewers and the risk of flooding downstream; • reducing the volumes and frequency of water flowing directly to watercourses or sewers

from developed sites; • improving water quality over conventional surface water sewers by removing pollutants

from diffuse pollutant sources; • reducing potable water demand through rainwater harvesting; • improving amenity through the provision of public open spaces and providing biodiversity

and wildlife habitat enhancements; and • replicating natural drainage patterns, including the recharge of groundwater so that base

flows are maintained.

It is proposed that a SuDS strategy is adopted as appropriate to satisfy the requirements of the proposed final restoration SWMP and current industry design criteria.

2.2 SWMP Design Principals: Water Quality

Incident rainfall onto active areas of landfilling is managed by the site leachate management system.

The landfill is being progressively restored with a minimum 1m depth of soils above an engineered cap. The soils are then progressively seeded and vegetated. Runoff is considered to be ‘clean’ and thus requires a single level of treatment in accordance with best practice guidance.

Furthermore, the site is actively managed; routine site walkover surveys are completed and water monitoring is undertaken in accordance with the site Environmental Permit. If and when areas of site are identified as posing a potential pollution hazard or silt is recorded in the site drainage system, remedial works are undertaken.

The proposed SWMP measures discussed below (e.g. open swales and infiltration basins / soakaways) will provide two levels of water treatment e.g. more than that required by best practice guidance. An additional safeguard is provided by the active site management. It is proposed therefore that treatment of runoff and consideration of water quality requires no further assessment.

It is out of the scope of this assessment, but is recommended that the site management and operation procedures are amended to include monitoring and maintenance of the surface water management measures detailed in the Sections that follow.

2.3 SWMP Design Principals: Design Storm Event

Current best practice for surface water management and SuDS Design (CIRIA Report C753) states the following with respect to the control of post development ‘Peak Runoff Rates’ and ‘Runoff Volume’:


SLR

SuDS Manual (CIRIA Report C753) – Section 24.10.1: “Additional runoff volumes from developments can cause increases in flood risk downstream of the site, even where peak flows from the site are controlled to greenfield rates. Therefore, for extreme events, in addition to the standard for controlling the peak rate of runoff, there is also a standard that requires runoff volume control for the 1:100 year, 6 hour event. This is particularly critical for catchments that are susceptible to flooding downstream of the proposed development. The difference in runoff volume between the development state and the equivalent greenfield (or possibly pre-development state where this is considered to be acceptable) is termed the Long-Term Storage Volume. It is this volume that should be prevented from leaving the site (via rainwater harvesting and/or infiltration) or, where this is not possible, controlled so that it discharges at very low rates that will have negligible impact on downstream flood risk. Only the greenfield (or pre-developed) runoff volume should be allowed to discharge at greenfield (or pre-developed) rates. Where there is extra volume generated by the development that has to be discharged (because there are no opportunities for it to be infiltrated and/or used on site), this volume should be released at a very low rate (e.g. <2/l/s/ha or as agreed with the local drainage approving body and/or environmental regulator) and the 1:100 year greenfield allowable runoff rate reduced to take account of this extra discharge (Kellagher, 2002). An alternative approach to managing the extra runoff volumes from extreme events separately from the main drainage system is to release all runoff (above the 1 year event) from the site at a maximum rate of 2 l/s/ha or QBAR, whichever is the higher value (or as agreed with the drainage approving body and/or environmental regulator). This avoids the need to undertake more detailed calculations and modelling. Kellagher (2002) demonstrates that if discharges are not limited to less than 3 l/s/ha, the drainage system will generally not be effective at retaining sufficient water on the site to prevent an increase in flood risk in the receiving catchment. A discharge limit of 2 l/s/ha (or QBAR, which allows for higher discharge rates for specific soil types) has generally been accepted as an appropriate industry standard in the UK, unless alternative site or catchment specific limits are agreed based on local risk evaluation.”

It is noted that guidance is currently being finalised by the Environment Agency (EA) which is aimed at providing specific design basis guidance for the “sizing surface water management systems at landfill sites”. The draft guidance recognises the following with respect to design return periods: EA Sizing of Surface Water Management Systems and Landfill Sites – Section 2.6

“For existing sites it may be more appropriate to use an alternative return period dependent on the sensitivity of the site and local receptors. For example a reduced return period such as a 1 in 10

year event may be a more appropriate for an existing site with limited additional space for the construction of ponds.”

The design criteria in CIRIA Report C753 is the most robust and conservative approach for assessing / designing surface water management measures. It is recognised by the EA however, for existing landfill sites it may not be possible to adopt best practice drainage design standards – in these instances it is appropriate to use a lesser design standard.


SLR

2.4 SWMP Design Principals: Perimeter Swale Sizing

Peak Discharge Rates

To assess the hydraulic sizing and geometry of the proposed perimeter swales the peak flow in each swale is determined at the downstream point of the swale, using the industry standard Modified Rational Method, where:

𝑄𝑄𝑝𝑝 = 2.78𝐶𝐶𝑣𝑣𝑖𝑖𝑖𝑖

Qp = Peak Flow (l/s) Cv = Runoff Coefficient (dim) i = Rainfall Intensity (mm/hr) A = Contributing Area (ha) 2.78 = Unit Conversion Factor

Specification of the minimum hydraulic sizing of the proposed swales is necessary to ensure sufficient hydraulic capacity to convey the anticipated design flows from each landfill sub-catchment.

Rainfall Intensity (i) is extracted from the FEH Online Depth Duration Frequency (DDF) modelling within WINDES for a range of return periods plus climate change. A 40% increase on the rainfall intensities is applied to account of future climate change and is based on the Flood risk assessments: climate change allowances1 guidance.

With reference to the National Coal Board guidance the Runoff Coefficient (Cv) is estimated to be 0.60 for the site taking into account the various vegetated surfaces and restoration contours.

Swale Sizing

The swale geometry required to convey the anticipated peak flow has been determined through application of Manning’s Equation (as recommended by CIRIA C753):

𝑄𝑄 = 1𝑛𝑛𝑖𝑖5 3�

𝑃𝑃2 3�𝑆𝑆𝑂𝑂

12�

Where Q = Flow (m3/s) n = Manning’s coefficient (dim) A = Cross Sectional Area (m2) P = Wetted perimeter (m) SO = Slope (dim) The Manning’s ‘n’ coefficient of the proposed swales, established from experience and referenced to respected literature2, has been estimated to be 0.033.

Appendix A presents the design calculations and minimum required geometry to convey the estimated design peak flows.

1 Environment Agency, 2016. Flood risk assessments: climate change allowances 2 Chow, V.T. (1959). Open Channel Hydraulics


SLR

2.5 SWMP Design Principals: Perimeter Swale Design The proposed surface water swales have been designed with: • embankment side slopes of approximately 1:2 which is deemed shallow enough for

geotechnical stability but steep enough to minimise the width of the swales; • to be shallow so that they do not affect the integrity of landfill capping system; and • with a shallow longitudinal fall to minimise the potential for erosion and maximise the

potential for the deposition of any entrained suspended solids.

Figure 3 provides a schematic for the swale design that is proposed at the site.

Figure 3 Schematic Swale Design

Figure 3 above also includes the equation used to calculate the Cross Sectional Area [A] for the swales and should be used to verify [A] of each proposed swale on site and check this against the required minimum [A] as specified in Appendix A.

Erosion and Sediment Control

It is proposed that reaches of swales prone to silting are actively managed.

In-channel silt traps strategically placed across the channel width can be used to slow the rate of runoff, allow sediment deposition, and targeted locations for site maintenance.

A typical arrangement for in-channel silt control is presented in Figure 4. Other arrangements are available such as sand bag placement and silt curtains, and any measures to be implemented are at the discretion of Veolia.


SLR

Figure 4 Typical Stone Check Dam Arrangement

Erosion control within the proposed swales should be provided in the form of stone rip-rap (50-100mm diameter) or elsewhere erosion is recorded.

Photograph 1 shows a recently constructed swale on a landfill cap and is similar in design to that proposed at Ling Hall.

Photograph 1 – Recently Constructed Landfill Cap Swale

Photograph 2 also shows a recently constructed landfill cap swale, but with an upslope sacrificial ditch that affords protection of the swale while vegetation in the swale establishes (again, an approach that could be adopted at Ling Hall, see Section 4).


SLR

Photograph 2 – Sacrificial ‘Protection’ Ditch upslope of Landfill Cap Swale

2.6 SWMP Design Principals: Infiltration Rates and Basins

It is proposed that surface water collected by the perimeter swales is routed to specifically constructed infiltration basins. The basins will be used to further attenuate runoff, provide temporary storage of runoff and allow infiltration of runoff to the surrounding in-situ sand and gravels.

The proposed base of the infiltration ponds is above the highest recorded groundwater levels. The infiltration basins have been specified to be shallow and to have side slopes of 1V:3H. The inflow to the proposed basins should include erosion protection, such as a gabion mattress, to dissipate the inflow and to minimise erosion potential (see Photograph 3).

Photograph 3 – Pond Inflow with Gabion Mattress to Dissipate Inflow Velocity

Photograph 3 also shows an aggregate/discard brick lined access track on the pond site to facilitate access for routine maintenance.


SLR

On site soakaway tests were carried out on 21 April 2009 and 13 May 2009 by Veolia. The following trial pits were used to determine representative infiltration rates for the infiltration basins (trial pit locations are detailed on Drawing No. 1):

• trial pit TPS2/09 was used to determine an infiltration rate of 0.021276m/hr • trial pit TPS3/09 was used to determine an infiltration rate of 0.03924m/hr

The infiltration rates incorporated in the WinDES models are:

• Attenuation features A, B - 0.021276m/hr • Attenuation features C, D and E - 0.03924m/hr


SLR

3.0 APPROVED RESTORATION SURFACE WATER MANAGEMENT SYSTEM

The proposed surface water management system for the approved restoration profile is shown on Drawing No. 1. It is proposed that a number of open surface water swales are used to convey, under gravity, runoff shed from the restoration slopes to a number of perimeter infiltration basins.

3.1 Infiltration Pond Details

Table 3-1 presents the key parameters used to assess the hydraulic performance of proposed infiltration ponds.

Table 3-1 Approved Restoration: Infiltration Pond Details

Parameter Description Unit Pond A Pond B Pond C Pond D Pond E Total Catchment Area ha 23.875 27.099 18.186 14.972 1.300

Effective Impermeable Area ha 14.325 16.260 10.912 8.983 0.780 Crest Elevation mAOD 111 110 109 109 110

Min. Base Elevation mAOD 110 109 108.5 108.5 109.5 Max. Pond Depth m 1 1 0.5 0.5 0.5

Approximate Embankment Gradient 1 in X 3 3 3 3 3

Max. Pond Surface Area m2 18900 18300 27100 26200 7500

Inflow Swale Invert Level mAOD 110.35 (Swale A)

109.6 (North) 109.4

(South)

108.5 (South) 108.7

(North)

108.5 (North) 108.7

(South)

109.7 (South)

3.2 Hydraulic Performance

Using the infiltration basin geometry in Table 3-1, Table 3-2 summarises the hydraulic performance of the proposed infiltration basins using the MicroDrainage software suite. The proposed SuDS features have been modelled using MicroDrainage for a range of AEP events up to and including the design 1% plus 40% climate change event. The results are presented in Table 3-2. Each return period has been modelled for a range of storm durations from 15 to 10080 minutes for both summer and winter storm profiles. The data from the critical storm event, which generates the largest required storage volume / gives rise to the highest water level in the pond, is selected to report in the summary tables. A copy of the full MicroDrainage modelling extracts is included as Appendix B. Where the proposed infiltration basin can accommodate runoff shed from a storm with an annual exceedance probability of 1% + 40% (allowance for climate change) no further analysis has been undertaken, as it has been shown that the infiltration basin can constructed in accordance with current best practice storm intensity and return period guidance. If it has been shown that there is in-sufficient space to construct an infiltration pond in accordance with best practice guidance hydraulic standards, lesser storm return periods have been considered to assess what design standard can be accommodated.


SLR

Table 3-2 SuDS Site Control: Hydraulic Modelling Summary

Attenuation Feature Modelling Parameter Unit

Annual Exceedance Probability of Occurrence (%)

50 100 100+40%CC

POND A

Critical Storm Duration (Winter) mins - - 960 Max Attenuated Water Depth m - - 0.686

Max Water Level mAOD - - 110.686 Freeboard Allowance mm - - 0.314

Total Attenuation Storage Volume m3 - - 12061.2 Status - - - OK

POND B

Critical Storm Duration (Winter) mins - 960 1440 Max Attenuated Water Depth m - 0.556 0.824

Max Water Level mAOD - 109.556 109.824 Freeboard Allowance mm - 0.444 0.176

Total Attenuation Storage Volume m3 - 9441.8 14196.9 Status - - OK FLOOD RISK

POND C

Critical Storm Duration (Winter) mins - 240 360 Max Attenuated Water Depth m - 0.182 0.275

Max Water Level mAOD - 108.682 108.775 Freeboard Allowance mm - 0.318 0.225


POND D

Critical Storm Duration mins - 240 360 Attenuated Water Depth m - 0.143 0.217

Water Level mAOD - 108.643 108.717 Freeboard Allowance mm - 0.357 0.283


POND E

Critical Storm Duration mins - - 180 Attenuated Water Depth m - - 0.085

Water Level mAOD - - 109.585 Freeboard Allowance mm - - 0.415

Total Attenuation Storage Volume m3 - - 367.8 Status - - - OK

The hydraulic modelling results summarised in Table 3-2 confirms Pond A and E can readily accommodate a design 1% AEP plus 40% Climate Change storm event with an appropriate freeboard (minimum 300mm). Ponds B, C and D can accommodate a design 1% AEP storm event with an appropriate freeboard, but not with the addition of a 40% allowance for climate change. Given the space constraints at these locations it is considered that this optimisation is an acceptable and reasonably practical design taking cognisance of the EA’s draft guidance for surface water management at landfills.


SLR

4.0 POTENTIAL MAINTENANCE REQUIREMENTS

4.1 Potential Maintenance Schedule – Swales

Swales are shallow, flat bottomed, vegetated open channels designed to convey, treat and often attenuate surface water runoff. Swales can adopt a variety of profiles and can be uniform or non-uniform and can incorporate a range of different planting strategies. They can incorporate check dams or berms to slow the rate of flow within the swale.

The SuDS Manual identifies 3no. types of swale:

• conveyance and attenuation swale; • dry or enhanced swale (which incorporates a filter trench below the bed of the swale);

and • wet swale (design to maintain wet or marshy conditions in the base of the swale).

Conveyance and attenuation swales have been proposed at Ling Hall.

With regard to construction and maintenance, the following will affect the maintenance requirements of swales:

1. grass swales should be clearly marked out before site work begins and protected by

signage and silt fencing where appropriate to avoid their disturbance during construction;

2. where feasible swales should not receive any runoff until the vegetation is fully established and the contributing catchment to the swale is not producing sediment loads that might cause siltation of the swale (see Photograph 2);

3. maintenance of swales is relatively straightforward and typically there should be no

amount of extra work for a swale over and above what might be required for standard open space maintenance;

4. mowing of grass in swales should ideally retain grass lengths of 75 – 150mm across the

‘main treatment surface’; and

5. litter (including leaf) and debris removal should be undertaken routinely and materials collected removed from site.

4.2 Potential Maintenance Schedule – Infiltration Systems & Soakaways With regard to construction and maintenance, the maintenance requirements of infiltration systems and soakaways is particularly sensitive to the following factors: 1. the frequency of maintenance and the risk of sediment being introduced to the system

(and thereby reducing the available storage volume and infiltration capacity of the soils surrounding the infiltration system);

2. if maintenance is not undertaken for long periods sediment deposits can become hard-

packed and require considerably more effort to remove;

3. an easement should be included in the site design to allow long-term access to the infiltration systems for routine maintenance equipment (thereby reducing costs with difficult and costly mobilisation of maintenance equipment);


SLR

4. effective monitoring of infiltration features can provide important information with regard

to sediment build up and therefore of future maintenance requirements or measures that might be introduced upstream of the infiltration features to reduce sediment build up;

5. regular mowing of infiltration basins is only required along maintenance access routes and amenity areas (e.g. footpaths), the remaining areas can be managed as ‘meadows’ thereby reducing maintenance requirements; and

6. grass cutting of infiltration basins may need to accommodate specific sward mixes and thus may require specific a specific maintenance, which includes removal of invasive species.


SLR

5.0 CONCLUSIONS

SLR Consulting Ltd (SLR) has been appointed by Veolia to prepare an outline Surface Water Management Plan (SWMP) suitable for the final restoration of the Ling Hall Landfill Site located at Coalpit Lane, Wolston, Rugby, CV23 9HH

This SWMP has been informed by a site walkover survey and has been prepared in consultation with Veolia.

The Landfill is currently active and surface water runoff is managed using a network of informal drains, ditches and ponds.

The SWMP therefore has been prepared to assess the management and control of surface water shed from site. It assesses the likely volumes of surface water runoff that might be shed from the fully restored site.

This assessment takes due cognisance of current best practice for surface water management at development sites (i.e. CIRIA Report C753) and specific draft guidance by the Environment Agency relating to surface water management at landfill sites.

Hydraulic analysis / modelling of the SWMP features has been conducted to current design standards (taking account of the EA’s new climate change guidance) and demonstrates that the proposed system has adequate capacity to safely and sustainably manage surface water runoff.

It is recommended that a formal maintenance schedule is developed for the site to ensure that the performance of the surface water management system is maintained (i.e. inspection, cleaning and removal of debris etc. from ditches, culverts and hydraulic controls). Details of potential maintenance tasks and frequencies are given.


SLR

6.0 CLOSURE

This report has been prepared by SLR Consulting Limited with all reasonable skill, care and diligence, and taking account of the manpower and resources devoted to it by agreement with the client. Information reported herein is based on the interpretation of data collected and has been accepted in good faith as being accurate and valid.

This report is for the exclusive use of Veolia Environmental Services Ltd; no warranties or guarantees are expressed or should be inferred by any third parties. This report may not be relied upon by other parties without written consent from SLR.

SLR disclaims any responsibility to the client and others in respect of any matters outside the agreed scope of the work.

DRAWINGS

SLR

Weighbridges

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TPS1/09

TPS2/09

TPS3/09

TPS4/09

POND E

CREST LEVEL - 110

INVERT LEVEL - 109.5

POND B

CREST LEVEL - 110

INVERT LEVEL - 109

POND C

CREST LEVEL - 109


POND A

CREST LEVEL - 111

INVERT LEVEL - 110

POND D

CREST LEVEL - 109


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POND E -

SOUTH

POND D -

NORTH

POND D -

SOUTH

POND C -

NORTH

POND C -

SOUTH

POND B -

SOUTH

POND B -

NORTH

Existing Wetland

Area

Existing Wetland

Area

A

A

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MIN 1000mmMIN 2600mm

MIN 650mm

1

44

1

GRASS WITHIN SWALE TO BE

SEEDED UNLESS EARLY EROSION

CONTROL IS REQUIRED. IN WHICH

CASE TURF SHOULD BE USED.

RUNOFF

MIN 1000mm

TOPSOIL

IN-SITU SAND

AND GRAVEL

EDGE OF

CONTAINMENT

LANDFILL

RUNOFF DEFLECTION

BUND

500mm

2

1

2

1

0.3m

GROUNDWATER TABLE IN

SAND AND GRAVEL

DETAIL AA - TYPICAL SWALE A CROSS SECTION

SCALE 1:50

LANDFILL SIDEWALL

LINING SYSTEM

N

Contains OS data © Crown copyright [and database rights] (2015) 0100031673.Contains public sector information licensed under Open government Licence v3.0© Crown copyright [and database rights] 0100031673 Expires

214 UNION STREET ABERDEEN AB10 1TL T: +44 (0)1224 517405

NO. 68 STIRLING BUSINESS CENTRE WELLGREEN STIRLING FK8 2DZ T: +44 (0)1786 239900

BUROCLUB 157/155 COURS BERRIAT 38028 GRENOBLE CEDEX 1 FRANCE T: + 33 4 76 70 93 41

www.slrconsulting.com

NOTES

LEGEND

Scale Date

TREENWOOD HOUSE ROWDEN LANE BRADFORD-ON-AVON WILTS. BA15 2AU T: 01225 309400 F: 01225 309401

LANGFORD LODGE 109 PEMBROKE ROAD CLIFTON, BRISTOL BS8 3EU T: 01179 064280 F: 01173 179535

FULMAR HOUSE BEIGNON CLOSE OCEAN WAY CARDIFF. CF24 5PB T: 0292 049 1010 F: 029 2048 7903

4 WOODSIDE PLACE CHARING CROSS GLASGOW G3 7QF T: 0141 353 5037 F: 0141 353 5038

4/5 LOCHSIDE VIEW EDINBURGH PARK EDINBURGH EH12 9DH T: +44 (0)131 335 6830

8 STOW COURT STOW-CUM-QUY CAMBRIDGE CAMBRIDGESHIRE. CB25 9AS T: 01223 813805 F: 01223 813783

65 WOODBRIDGE ROAD GUILDFORD SURREY GU1 4RD T:+44 (0)1483 889800

SUITE 1,JASON HOUSE KERRY HILL HORSFORTH LEEDS. LS18 4JR T: 0113 2580650 F: 0113 2818832

19 HOLLINGWORTH COURT TURKEY MILL MAIDSTONE KENT. ME14 5PP T: 01622 609242 F: 01622 695872

SAILORS BETHEL HORATIO STREET NEWCASTLE UPON TYNE TYNE AND WEAR. NE1 2PE T: 0191 261 1966 F: 0191 230 2346

ASPECT HOUSE ASPECT BUSINESS PARK BENNERLEY ROAD NOTTINGHAM. NG6 8WR T: 01159 647280 F: 01159 751576

7 WORNAL PARK MENMARSH ROAD WORMINGHALL, AYLESBURY BUCKS. HP18 9PH T: 01844 337380 F: 01844 337381

2ND FLOOR HERMES HOUSE HOLSWORTH PARK OXON BUSINESS PARK SHREWSBURY, SY3 5HJ T: 01743 239250

8TH FLOOR, QUAY WESTMEDIACITYUK

TRAFFORD WHARF ROADMANCHESTER

M17 1HH, UKT:+44 (0)161 872 7564

LEGEND

69 POLSLOE ROAD EXETER DEVON EX1 2NF T: +44 (0)1392 490152 F: +44(0)1392 495572

WATERHOUSE BUSINESS CENTRE UNIT 77, 2 CROMAR WAY CHELMSFORD ESSEX CM1 2QE T: 01245 392170 F: 01245 392171 SLR CONSULTING IRELAND 7 DUNDRUM BUSINESS PARK WINDY ARBOUR DUBLIN 14 T: +353-1-2964667 F: +353-1-2964676 8 PARKER COURT STAFFORDSHIRE TECHNOLOGY PARK, BEACONSIDE, STAFFORD ST18 OWP T: 01785 241755 F: 01785 241780 SUITE 1 POTTERS QUAY 5 RAVENHILL ROAD BELFAST BT6 8DN NORTHERN IRELAND T: +44 (0)28 9073 2493

42

8.0

01

56

.0

01

92

.1

8.0

01

.0

.d

wg

UNIT 2, NEWTON BUSINESS CENTRE THORNCLIFFE PARK ESTATE NEWTON CHAMBERS ROAD CHAPELTOWN SHEFFIELD, S35 2PW T:+44 (0)114 2455153 SUITE 5, BRINDLEY COURT GRESLEY ROAD SHIRE BUSINESS PARK WORCESTER WR4 9FD T: +44 (0)1905 751310 F: +44 (0)1905 751311 2 LINCOLN STREET LANE COVE NEW SOUTH WALES 2066 AUSTRALIA T: 61 2 9427 8100 F: 61 2 9427 8200 83 VICTORIA STREET LONDON SW1H 0HW T: 44 (0)203 691 58102

© This drawing and its content are the copyright of SLR Consulting Ltd and may not be reproduced or amended except by prior written permission. SLR Consulting Ltd accepts no liability for any amendments made by other persons.

© This drawing and its content are the copyright of SLR Consulting Ltd and may not be reproduced or amended except by prior written permission. SLR Consulting Ltd accepts no liability for any amendments made by other persons.

DRAWING 1

1:6000 @ A3 APRIL 2017

APPROVED RESTORATION -

PROPOSED LAYOUT

DRAWING_TITLE_3

SURFACE WATER MANAGEMENT

PLAN

PROJECT_TITLE_3

LING HALL LANDFILL

SITE_NAME_2

[DD/MM/YY]2015

OPEN SURFACE WATER

SWALES

SURFACE WATER CATCHMENT

BOUNDARY

INDICATIVE ATTENUATION AND

SOAKAWAY AREAS

é

TRIAL PITS

1. DRAWING IS BASED ON VEOLIA

ENVIRONMENTAL SERVICES SITE PLUS INFILL

CONTOURS DRAWING DATED AUGUST 2016.

2. DITCH ROUTING AND POND DIMENSIONS

ARE INDICATIVE AND SUBJECT TO DETAILED

DESIGN. ACTUAL LOCATIONS MAY VARY

FROM THOSE SHOWN TO FIT WITH LANDFILL

SERVICES AT TIME OF INSTALLATION.

APPENDIX – A Swale / Ditch Outline Design Calculations and Minimum Required Geometry

SLR

Veolia Environmental Services

Ling Hall Landfill

Ling Hall Surface Water Management Plan

Appendix A

428.00156.00192

December 2016

Summary Spreadsheet of Minimum Required Ditch Design Details - Approved Restoration Scheme

Modified Rational Method Parameters

Adopted landfill runoff coefficient [C] 0.6

1hr 1:100 + 40 CC year Rainfall Intensity [i] 61.9

Ditch ID(1)

Ditch Type(2)

Catchment

Area [A] in

(ha)(3)

Peak Flow

to Convey

[Qp] in

(m3/s)

(4)

Min. Base

Width [X] in

(m)

Min. Depth

[Y] in (m)

Side Width

[Z] in (m)

Min. Cross

Sectional Area

[A] (m2)

Ave.

Longitudinal

Gradient [So] in

(1 in X)(5)

Ave. Side Slope

Gradient in (1 in

X)

Calculated

Conveyance

Capacity [Qc] in

(m3/s)

(6)

Pond A-East (Swale A) Swale 23.87 2.47 1.00 0.65 2.60 2.34 100 4 3.63

Pond B-NORTH Swale 5.89 0.61 0.60 0.40 0.80 0.56 100 2 0.64

Pond B-SOUTH Swale 19.38 2.00 1.00 0.60 1.20 1.32 100 2 2.01

Pond C-SOUTH Swale 13.59 1.40 1.20 0.50 1.00 1.10 100 2 1.55

Pond C-NORTH Swale 1.88 0.19 0.20 0.30 0.60 0.24 100 2 0.21

Pond D-NORTH Swale 9.05 0.93 0.60 0.50 1.00 0.80 100 2 1.04

Pond D-SOUTH Swale 3.30 0.34 0.60 0.30 0.60 0.36 100 2 0.35

Pond E-SOUTH Swale 1.22 0.13 0.20 0.30 0.60 0.24 100 2 0.21

QP = 2.78CiA

SLR Consulting Ltd

APPENDIX - B Approved Restoration Scheme MicroDrainage Pond Modelling Extracts

SLR

SLR Consulting Limited Page 1

4/5 Lochside View

Edinburgh Park

Midlothian Edinburgh EH12 9DH

Date 07/12/2016 22:21 Designed by gfrisby

File POND_A_CATCHMENT_A.SRCX Checked by

XP Solutions Source Control 2015.1

Summary of Results for 100 year Return Period (+40%)

©1982-2015 XP Solutions

Half Drain Time : 1836 minutes.

Storm

Event

Max

Level

(m)

Max

Depth

(m)

Max

Infiltration

(l/s)

Max

Volume

(m³)

Status

15 min Summer 110.270 0.270 52.4 4629.2 O K30 min Summer 110.319 0.319 53.0 5488.4 O K60 min Summer 110.375 0.375 53.7 6474.3 O K120 min Summer 110.437 0.437 54.4 7580.0 O K180 min Summer 110.476 0.476 54.9 8263.7 O K240 min Summer 110.503 0.503 55.2 8752.9 O K360 min Summer 110.541 0.541 55.6 9424.8 O K480 min Summer 110.565 0.565 55.9 9864.7 O K600 min Summer 110.582 0.582 56.1 10168.3 O K720 min Summer 110.594 0.594 56.3 10380.3 O K960 min Summer 110.599 0.599 56.3 10470.6 O K1440 min Summer 110.589 0.589 56.2 10300.2 O K2160 min Summer 110.567 0.567 56.0 9889.6 O K2880 min Summer 110.544 0.544 55.7 9492.2 O K4320 min Summer 110.480 0.480 54.9 8337.7 O K5760 min Summer 110.426 0.426 54.3 7370.6 O K7200 min Summer 110.377 0.377 53.7 6514.7 O K8640 min Summer 110.334 0.334 53.2 5746.0 O K10080 min Summer 110.294 0.294 52.7 5047.1 O K

15 min Winter 110.302 0.302 52.8 5190.8 O K

Storm

Event

Rain

(mm/hr)

Flooded

Volume

(m³)

Time-Peak

(mins)

15 min Summer 174.644 0.0 2730 min Summer 103.973 0.0 4160 min Summer 61.900 0.0 70120 min Summer 36.852 0.0 130180 min Summer 27.209 0.0 190240 min Summer 21.939 0.0 248360 min Summer 16.198 0.0 368480 min Summer 13.062 0.0 486600 min Summer 11.053 0.0 606720 min Summer 9.644 0.0 724960 min Summer 7.683 0.0 9621440 min Summer 5.577 0.0 14002160 min Summer 4.048 0.0 17162880 min Summer 3.225 0.0 21044320 min Summer 2.263 0.0 29005760 min Summer 1.760 0.0 36967200 min Summer 1.449 0.0 44808640 min Summer 1.236 0.0 528010080 min Summer 1.080 0.0 6056

15 min Winter 174.644 0.0 27


4/5 Lochside View

Edinburgh Park







Storm

Event

Max

Level

(m)

Max

Depth

(m)

Max

Infiltration

(l/s)

Max

Volume

(m³)

Status

30 min Winter 110.357 0.357 53.5 6157.8 O K60 min Winter 110.420 0.420 54.2 7272.3 O K120 min Winter 110.491 0.491 55.1 8530.2 O K180 min Winter 110.535 0.535 55.6 9316.9 O K240 min Winter 110.566 0.566 55.9 9885.8 O K360 min Winter 110.610 0.610 56.5 10680.2 O K480 min Winter 110.640 0.640 56.8 11214.8 O K600 min Winter 110.661 0.661 57.1 11596.7 O K720 min Winter 110.676 0.676 57.3 11876.3 O K960 min Winter 110.686 0.686 57.4 12061.2 O K1440 min Winter 110.685 0.685 57.4 12037.1 O K2160 min Winter 110.659 0.659 57.0 11556.1 O K2880 min Winter 110.630 0.630 56.7 11045.5 O K4320 min Winter 110.546 0.546 55.7 9513.1 O K5760 min Winter 110.469 0.469 54.8 8139.6 O K7200 min Winter 110.399 0.399 54.0 6897.6 O K8640 min Winter 110.335 0.335 53.2 5778.1 O K10080 min Winter 110.278 0.278 52.5 4771.7 O K

Storm

Event

Rain

(mm/hr)

Flooded

Volume

(m³)

Time-Peak

(mins)

30 min Winter 103.973 0.0 4160 min Winter 61.900 0.0 70120 min Winter 36.852 0.0 128180 min Winter 27.209 0.0 186240 min Winter 21.939 0.0 244360 min Winter 16.198 0.0 362480 min Winter 13.062 0.0 478600 min Winter 11.053 0.0 594720 min Winter 9.644 0.0 710960 min Winter 7.683 0.0 9401440 min Winter 5.577 0.0 13862160 min Winter 4.048 0.0 19922880 min Winter 3.225 0.0 22524320 min Winter 2.263 0.0 31565760 min Winter 1.760 0.0 40327200 min Winter 1.449 0.0 48408640 min Winter 1.236 0.0 569610080 min Winter 1.080 0.0 6456


4/5 Lochside View

Edinburgh Park





Rainfall Details


Rainfall Model FEHReturn Period (years) 100

Site Location GB 444900 274600 SP 44900 74600C (1km) -0.027D1 (1km) 0.376D2 (1km) 0.334D3 (1km) 0.251E (1km) 0.300F (1km) 2.409

Summer Storms YesWinter Storms YesCv (Summer) 0.750Cv (Winter) 0.840

Shortest Storm (mins) 15Longest Storm (mins) 10080

Climate Change % +40

Time Area Diagram

Total Area (ha) 14.325

Time

From:

(mins)

To:

Area

(ha)

Time

From:

(mins)

To:

Area

(ha)

Time

From:

(mins)

To:

Area

(ha)

0 4 4.775 4 8 4.775 8 12 4.775


4/5 Lochside View

Edinburgh Park





Model Details


Storage is Online Cover Level (m) 111.000

Infiltration Basin Structure

Invert Level (m) 110.000 Safety Factor 2.0Infiltration Coefficient Base (m/hr) 0.02100 Porosity 1.00Infiltration Coefficient Side (m/hr) 0.02100

Depth (m) Area (m²) Depth (m) Area (m²)

0.000 16900.0 1.000 18900.0


4/5 Lochside View

Edinburgh Park



File POND_B_CATCHMENT_B.SRCX Checked by


Summary of Results for 100 year Return Period



Storm

Event

Max

Level

(m)

Max

Depth

(m)

Max

Infiltration

(l/s)

Max

Volume

(m³)

Status


15 min Winter 109.251 0.251 50.8 4199.4 O K

Storm

Event

Rain

(mm/hr)

Flooded

Volume

(m³)

Time-Peak

(mins)


15 min Winter 124.746 0.0 26


4/5 Lochside View

Edinburgh Park







Storm

Event

Max

Level

(m)

Max

Depth

(m)

Max

Infiltration

(l/s)

Max

Volume

(m³)

Status


Storm

Event

Rain

(mm/hr)

Flooded

Volume

(m³)

Time-Peak

(mins)



4/5 Lochside View

Edinburgh Park





Rainfall Details






Climate Change % +0

Time Area Diagram


Time

From:

(mins)

To:

Area

(ha)

Time

From:

(mins)

To:

Area

(ha)

Time

From:

(mins)

To:

Area

(ha)

0 4 5.419 4 8 5.419 8 12 5.419


4/5 Lochside View

Edinburgh Park





Model Details






0.000 16500.0 1.000 18300.0


4/5 Lochside View

Edinburgh Park








Storm

Event

Max

Level

(m)

Max

Depth

(m)

Max

Infiltration

(l/s)

Max

Volume

(m³)

Status

15 min Summer 109.314 0.314 51.4 5262.2 O K30 min Summer 109.371 0.371 52.0 6241.4 O K60 min Summer 109.437 0.437 52.8 7370.9 O K120 min Summer 109.510 0.510 53.5 8647.5 O K180 min Summer 109.556 0.556 54.0 9446.4 O K240 min Summer 109.589 0.589 54.4 10024.7 O K360 min Summer 109.635 0.635 54.9 10833.5 O K480 min Summer 109.666 0.666 55.2 11379.1 O K600 min Summer 109.688 0.688 55.4 11770.0 O K720 min Summer 109.704 0.704 55.6 12056.6 Flood Risk960 min Summer 109.715 0.715 55.7 12248.4 Flood Risk1440 min Summer 109.713 0.713 55.7 12219.2 Flood Risk2160 min Summer 109.690 0.690 55.5 11801.5 O K2880 min Summer 109.666 0.666 55.2 11383.3 O K4320 min Summer 109.595 0.595 54.4 10128.7 O K5760 min Summer 109.536 0.536 53.8 9098.1 O K7200 min Summer 109.484 0.484 53.3 8193.0 O K8640 min Summer 109.436 0.436 52.7 7369.9 O K10080 min Summer 109.393 0.393 52.3 6617.2 O K

15 min Winter 109.351 0.351 51.8 5899.7 O K

Storm

Event

Rain

(mm/hr)

Flooded

Volume

(m³)

Time-Peak

(mins)


15 min Winter 174.644 0.0 27


4/5 Lochside View

Edinburgh Park







Storm

Event

Max

Level

(m)

Max

Depth

(m)

Max

Infiltration

(l/s)

Max

Volume

(m³)

Status

30 min Winter 109.415 0.415 52.5 7001.7 O K60 min Winter 109.489 0.489 53.3 8276.8 O K120 min Winter 109.572 0.572 54.2 9726.6 O K180 min Winter 109.624 0.624 54.8 10642.1 O K240 min Winter 109.662 0.662 55.2 11311.4 O K360 min Winter 109.715 0.715 55.7 12259.8 Flood Risk480 min Winter 109.752 0.752 56.1 12913.7 Flood Risk600 min Winter 109.779 0.779 56.4 13393.9 Flood Risk720 min Winter 109.799 0.799 56.6 13757.4 Flood Risk960 min Winter 109.816 0.816 56.8 14057.0 Flood Risk1440 min Winter 109.824 0.824 56.9 14196.9 Flood Risk2160 min Winter 109.805 0.805 56.7 13859.9 Flood Risk2880 min Winter 109.773 0.773 56.4 13289.1 Flood Risk4320 min Winter 109.684 0.684 55.4 11700.7 O K5760 min Winter 109.603 0.603 54.5 10274.5 O K7200 min Winter 109.529 0.529 53.7 8974.4 O K8640 min Winter 109.460 0.460 53.0 7779.8 O K10080 min Winter 109.397 0.397 52.3 6684.2 O K

Storm

Event

Rain

(mm/hr)

Flooded

Volume

(m³)

Time-Peak

(mins)



4/5 Lochside View

Edinburgh Park





Rainfall Details







Time Area Diagram


Time

From:

(mins)

To:

Area

(ha)

Time

From:

(mins)

To:

Area

(ha)

Time

From:

(mins)

To:

Area

(ha)

0 4 5.419 4 8 5.419 8 12 5.419


4/5 Lochside View

Edinburgh Park





Model Details






0.000 16500.0 1.000 18300.0


4/5 Lochside View

Edinburgh Park



File POND_C_CATCHMENT_C.SRCX Checked by





Storm

Event

Max

Level

(m)

Max

Depth

(m)

Max

Infiltration

(l/s)

Max

Volume

(m³)

Status


15 min Winter 108.614 0.114 132.9 2724.2 O K

Storm

Event

Rain

(mm/hr)

Flooded

Volume

(m³)

Time-Peak

(mins)


15 min Winter 124.746 0.0 25


4/5 Lochside View

Edinburgh Park







Storm

Event

Max

Level

(m)

Max

Depth

(m)

Max

Infiltration

(l/s)

Max

Volume

(m³)

Status


Storm

Event

Rain

(mm/hr)

Flooded

Volume

(m³)

Time-Peak

(mins)



4/5 Lochside View

Edinburgh Park





Rainfall Details






Climate Change % +0

Time Area Diagram


Time

From:

(mins)

To:

Area

(ha)

Time

From:

(mins)

To:

Area

(ha)

Time

From:

(mins)

To:

Area

(ha)

0 4 3.637 4 8 3.637 8 12 3.637


4/5 Lochside View

Edinburgh Park





Model Details






0.000 23600.0 1.000 27100.0


4/5 Lochside View

Edinburgh Park








Storm

Event

Max

Level

(m)

Max

Depth

(m)

Max

Infiltration

(l/s)

Max

Volume

(m³)

Status

15 min Summer 108.644 0.144 134.1 3430.6 O K30 min Summer 108.669 0.169 135.0 4031.7 O K60 min Summer 108.695 0.195 136.0 4668.7 O K120 min Summer 108.720 0.220 136.9 5269.8 Flood Risk180 min Summer 108.731 0.231 137.4 5545.1 Flood Risk240 min Summer 108.736 0.236 137.6 5672.5 Flood Risk360 min Summer 108.738 0.238 137.6 5713.6 Flood Risk480 min Summer 108.737 0.237 137.6 5685.2 Flood Risk600 min Summer 108.734 0.234 137.5 5625.8 Flood Risk720 min Summer 108.731 0.231 137.4 5547.2 Flood Risk960 min Summer 108.720 0.220 136.9 5267.0 Flood Risk1440 min Summer 108.697 0.197 136.1 4703.8 O K2160 min Summer 108.664 0.164 134.8 3924.0 O K2880 min Summer 108.636 0.136 133.8 3243.9 O K4320 min Summer 108.585 0.085 131.8 2029.4 O K5760 min Summer 108.556 0.056 130.7 1335.2 O K7200 min Summer 108.546 0.046 119.3 1080.8 O K8640 min Summer 108.540 0.040 103.6 941.8 O K10080 min Summer 108.535 0.035 91.8 835.6 O K

15 min Winter 108.662 0.162 134.7 3856.6 O K

Storm

Event

Rain

(mm/hr)

Flooded

Volume

(m³)

Time-Peak

(mins)


15 min Winter 174.644 0.0 26


4/5 Lochside View

Edinburgh Park







Storm

Event

Max

Level

(m)

Max

Depth

(m)

Max

Infiltration

(l/s)

Max

Volume

(m³)

Status

30 min Winter 108.690 0.190 135.8 4538.7 O K60 min Winter 108.720 0.220 136.9 5270.5 Flood Risk120 min Winter 108.749 0.249 138.1 5983.5 Flood Risk180 min Winter 108.763 0.263 138.6 6332.3 Flood Risk240 min Winter 108.771 0.271 138.9 6515.4 Flood Risk360 min Winter 108.775 0.275 139.1 6627.3 Flood Risk480 min Winter 108.773 0.273 139.0 6563.5 Flood Risk600 min Winter 108.769 0.269 138.8 6466.0 Flood Risk720 min Winter 108.764 0.264 138.6 6355.6 Flood Risk960 min Winter 108.748 0.248 138.0 5960.0 Flood Risk1440 min Winter 108.714 0.214 136.7 5119.9 Flood Risk2160 min Winter 108.665 0.165 134.9 3933.5 O K2880 min Winter 108.623 0.123 133.3 2916.9 O K4320 min Winter 108.557 0.057 130.8 1358.0 O K5760 min Winter 108.542 0.042 110.2 1001.5 O K7200 min Winter 108.535 0.035 91.8 830.1 O K8640 min Winter 108.530 0.030 78.7 711.6 O K10080 min Winter 108.527 0.027 69.6 626.7 O K

Storm

Event

Rain

(mm/hr)

Flooded

Volume

(m³)

Time-Peak

(mins)



4/5 Lochside View

Edinburgh Park





Rainfall Details







Time Area Diagram


Time

From:

(mins)

To:

Area

(ha)

Time

From:

(mins)

To:

Area

(ha)

Time

From:

(mins)

To:

Area

(ha)

0 4 3.637 4 8 3.637 8 12 3.637


4/5 Lochside View

Edinburgh Park





Model Details






0.000 23600.0 1.000 27100.0


4/5 Lochside View

Edinburgh Park



File POND_D_CATCHMENT_D.SRCX Checked by





Storm

Event

Max

Level

(m)

Max

Depth

(m)

Max

Infiltration

(l/s)

Max

Volume

(m³)

Status


15 min Winter 108.594 0.094 131.3 2226.9 O K

Storm

Event

Rain

(mm/hr)

Flooded

Volume

(m³)

Time-Peak

(mins)


15 min Winter 124.746 0.0 25


4/5 Lochside View

Edinburgh Park







Storm

Event

Max

Level

(m)

Max

Depth

(m)

Max

Infiltration

(l/s)

Max

Volume

(m³)

Status


Storm

Event

Rain

(mm/hr)

Flooded

Volume

(m³)

Time-Peak

(mins)



4/5 Lochside View

Edinburgh Park





Rainfall Details






Climate Change % +0

Time Area Diagram


Time

From:

(mins)

To:

Area

(ha)

Time

From:

(mins)

To:

Area

(ha)

Time

From:

(mins)

To:

Area

(ha)

0 4 2.994 4 8 2.994 8 12 2.994


4/5 Lochside View

Edinburgh Park





Model Details






0.000 23600.0 1.000 26200.0


4/5 Lochside View

Edinburgh Park








Storm

Event

Max

Level

(m)

Max

Depth

(m)

Max

Infiltration

(l/s)

Max

Volume

(m³)

Status


15 min Winter 108.633 0.133 132.4 3155.9 O K

Storm

Event

Rain

(mm/hr)

Flooded

Volume

(m³)

Time-Peak

(mins)


15 min Winter 174.644 0.0 26


4/5 Lochside View

Edinburgh Park







Storm

Event

Max

Level

(m)

Max

Depth

(m)

Max

Infiltration

(l/s)

Max

Volume

(m³)

Status

30 min Winter 108.656 0.156 133.0 3707.3 O K60 min Winter 108.680 0.180 133.7 4287.8 O K120 min Winter 108.702 0.202 134.4 4830.6 Flood Risk180 min Winter 108.713 0.213 134.7 5073.1 Flood Risk240 min Winter 108.717 0.217 134.8 5178.3 Flood Risk360 min Winter 108.717 0.217 134.8 5187.2 Flood Risk480 min Winter 108.714 0.214 134.7 5103.6 Flood Risk600 min Winter 108.710 0.210 134.6 5003.0 Flood Risk720 min Winter 108.704 0.204 134.4 4871.6 Flood Risk960 min Winter 108.688 0.188 133.9 4475.2 O K1440 min Winter 108.655 0.155 133.0 3677.0 O K2160 min Winter 108.610 0.110 131.7 2620.4 O K2880 min Winter 108.576 0.076 130.8 1798.4 O K4320 min Winter 108.544 0.044 115.0 1045.3 O K5760 min Winter 108.535 0.035 91.5 827.6 O K7200 min Winter 108.529 0.029 75.9 685.9 O K8640 min Winter 108.525 0.025 64.2 590.0 O K10080 min Winter 108.522 0.022 56.4 515.9 O K

Storm

Event

Rain

(mm/hr)

Flooded

Volume

(m³)

Time-Peak

(mins)



4/5 Lochside View

Edinburgh Park





Rainfall Details







Time Area Diagram


Time

From:

(mins)

To:

Area

(ha)

Time

From:

(mins)

To:

Area

(ha)

Time

From:

(mins)

To:

Area

(ha)

0 4 2.994 4 8 2.994 8 12 2.994


4/5 Lochside View

Edinburgh Park





Model Details






0.000 23600.0 1.000 26200.0


4/5 Lochside View

Edinburgh Park



File POND_E_CATCHMENT_E.SRCX Checked by





Storm

Event

Max

Level

(m)

Max

Depth

(m)

Max

Infiltration

(l/s)

Max

Volume

(m³)

Status


15 min Winter 109.561 0.061 25.1 264.7 O K

Storm

Event

Rain

(mm/hr)

Flooded

Volume

(m³)

Time-Peak

(mins)


15 min Winter 174.644 0.0 24


4/5 Lochside View

Edinburgh Park







Storm

Event

Max

Level

(m)

Max

Depth

(m)

Max

Infiltration

(l/s)

Max

Volume

(m³)

Status


Storm

Event

Rain

(mm/hr)

Flooded

Volume

(m³)

Time-Peak

(mins)



4/5 Lochside View

Edinburgh Park





Rainfall Details







Time Area Diagram


Time

From:

(mins)

To:

Area

(ha)

Time

From:

(mins)

To:

Area

(ha)

Time

From:

(mins)

To:

Area

(ha)

0 4 0.259 4 8 0.259 8 12 0.260


4/5 Lochside View

Edinburgh Park





Model Details






0.000 4230.0 1.000 7500.0

ABERDEEN 214 Union Street, Aberdeen AB10 1TL, UK T: +44 (0)1224 517405 AYLESBURY 7 Wornal Park, Menmarsh Road, Worminghall, Aylesbury, Buckinghamshire HP18 9PH, UK T: +44 (0)1844 337380 BELFAST Suite 1 Potters Quay, 5 Ravenhill Road, Belfast BT6 8DN, Northern Ireland T: +44 (0)28 9073 2493 BRADFORD ON AVON Treenwood House, Rowden Lane, Bradford on Avon, Wiltshire BA15 2AU, UK T: +44 (0)1225 309400 BRISTOL Langford Lodge, 109 Pembroke Road, Clifton, Bristol BS8 3EU, UK T: +44 (0)117 9064280 CAMBRIDGE 8 Stow Court, Stow-cum-Quy, Cambridge CB25 9AS, UK T: + 44 (0)1223 813805 CARDIFF Fulmar House, Beignon Close, Ocean Way, Cardiff CF24 5PB, UK T: +44 (0)29 20491010 CHELMSFORD Unit 77, Waterhouse Business Centre, 2 Cromar Way, Chelmsford, Essex CM1 2QE, UK T: +44 (0)1245 392170

DUBLIN 7 Dundrum Business Park, Windy Arbour, Dublin 14 Ireland T: + 353 (0)1 2964667 EDINBURGH 4/5 Lochside View, Edinburgh Park, Edinburgh EH12 9DH, UK T: +44 (0)131 3356830 EXETER 69 Polsloe Road, Exeter EX1 2NF, UK T: + 44 (0)1392 490152 GLASGOW 4 Woodside Place, Charing Cross, Glasgow G3 7QF, UK T: +44 (0)141 3535037 GRENOBLE BuroClub, 157/155 Cours Berriat, 38028 Grenoble Cedex 1, France T: +33 (0)4 76 70 93 41 GUILDFORD 65 Woodbridge Road, Guildford Surrey GU1 4RD, UK T: +44 (0)1483 889 800 LEEDS Suite 1, Jason House, Kerry Hill, Horsforth, Leeds LS18 4JR, UK T: +44 (0)113 2580650 LONDON 83 Victoria Street, London, SW1H 0HW, UK T: +44 (0)203 691 5810 MAIDSTONE 19 Hollingworth Court, Turkey Mill, Maidstone, Kent ME14 5PP, UK T: +44 (0)1622 609242

MANCHESTER 8th Floor, Quay West, MediaCityUK, Trafford Wharf Road, Manchester M17 1HH, UK T: +44 (0)161 872 7564 NEWCASTLE UPON TYNE Sailors Bethel, Horatio Street, Newcastle upon Tyne NE1 2PE, UK T: +44 (0)191 2611966 NOTTINGHAM Aspect House, Aspect Business Park, Bennerley Road, Nottingham NG6 8WR, UK T: +44 (0)115 9647280 SHEFFIELD Unit 2 Newton Business Centre, Thorncliffe Park Estate, Newton Chambers Road, Chapeltown, Sheffield S35 2PW, UK T: +44 (0)114 2455153 SHREWSBURY 2nd Floor, Hermes House, Oxon Business Park, Shrewsbury, SY3 5HJ, UK T: +44 (0)1743 239250 STAFFORD 8 Parker Court, Staffordshire Technology Park, Beaconside, Stafford ST18 0WP, UK T: +44 (0)1785 241755 STIRLING No. 68 Stirling Business Centre, Wellgreen, Stirling FK8 2DZ, UK T: +44 (0)1786 239900 WORCESTER Suite 5, Brindley Court, Gresley Road, Shire Business Park, Worcester WR4 9FD, UK T: +44 (0)1905 751310


2 June 2017 Report No. 173593.500.A0

APPENDIX B Surface water calculation sheets

Storage Volume Calculations

Hardstanding 0.9

Pre-Development

Site Areas:

Landscaping 150,600 m²

Hardstanding - m²

Combined Runoff Coefficient 0.600

Post-Development

Site Areas:


Hardstanding 588 m² Concrete foundations


Flow Rate Q (m3/s) = C i A

where C = coefficient of runoff; i = rainfall intensity; A = catchment area

then Runoff Volume = Q x Duration

150,600

0.601 0.600

Duration (mins) Rainfall (mm)

Volume of

Runoff (Post-

Development)

(m³)

Volume of

Runoff (Pre-

Development)

(m³)

Storage Required

to Retain to Pre-

Development

Rate (m³)

30 43 3,919 3,911 8

60 52 4,678 4,669 9

120 62 5,573 5,563 11

180 68 6,169 6,157 12

240 73 6,628 6,615 13

360 81 7,331 7,317 14

540 90 8,106 8,090 16

720 96 8,703 8,686 17

1080 104 9,451 9,432 18

1440 111 10,019 10,000 20

Maximum 20

100 year return period plus 20% Climate Change

Total Area m2

Combined Runoff Coefficient

Date: May 2017

Created by: M Goode


Hardstanding 0.9

Pre-Development

Site Areas:


Hardstanding - m²


Post-Development

Site Areas:







95,200

0.601 0.600


Volume of

Runoff (Post-

Development)

(m³)

Volume of

Runoff (Pre-

Development)

(m³)

Storage Required

to Retain to Pre-

Development

Rate (m³)

30 43 2,477 2,472 5

60 52 2,957 2,952 6

120 62 3,523 3,516 7

180 68 3,899 3,892 8

240 73 4,190 4,182 8

360 81 4,634 4,625 9

540 90 5,124 5,114 10

720 96 5,502 5,491 11

1080 104 5,974 5,963 12

1440 111 6,333 6,321 12

Maximum 12


Total Area m2


Date: May 2017

Created by: M Goode


Hardstanding 0.9

Pre-Development

Site Areas:


Hardstanding - m²


Post-Development

Site Areas:







63,000

0.601 0.600


Volume of

Runoff (Post-

Development)

(m³)

Volume of

Runoff (Pre-

Development)

(m³)

Storage Required

to Retain to Pre-

Development

Rate (m³)

30 43 1,639 1,636 3

60 52 1,957 1,953 4

120 62 2,332 2,327 5

180 68 2,581 2,576 5

240 73 2,773 2,767 5

360 81 3,067 3,061 6

540 90 3,391 3,384 7

720 96 3,641 3,634 7

1080 104 3,954 3,946 8

1440 111 4,191 4,183 8

Maximum 8


Total Area m2


Date: May 2017

Created by: M Goode


Hardstanding 0.9

Pre-Development

Site Areas:


Hardstanding - m²


Post-Development

Site Areas:







108,800

0.603 0.600


Volume of

Runoff (Post-

Development)

(m³)

Volume of

Runoff (Pre-

Development)

(m³)

Storage Required

to Retain to Pre-

Development

Rate (m³)

30 43 2,838 2,826 12

60 52 3,388 3,373 15

120 62 4,036 4,019 18

180 68 4,468 4,448 20

240 73 4,800 4,779 21

360 81 5,309 5,286 23

540 90 5,870 5,845 26

720 96 6,303 6,275 28

1080 104 6,845 6,814 30

1440 111 7,256 7,224 32

Maximum 32


Total Area m2


Date: May 2017

Created by: M Goode


2 June 2017 Report No. 173593.500.A0

APPENDIX C BGS - SuDS report

British Geological Survey N AT U" A L EN YlfltONH ENT ltESEA" CH COUNCIL

Karen Campbell Golder Associates Golder Associates Accounts Dept Attenborough House, Browns Lane Business Park Stanton-on-the-Wolds Nottingham NG12 SBL

Infiltration SuDS GeoReport:

This report provides information on the suitability of the subsurface for the installation of infiltration sustainable drainage systems (SuDS). It provides information on the properties of the subsurface with respect to significant constraints, drainage, ground stability and groundwater quality protection.

Report Id: GR_ 216084/1

Client reference: GAUK115143/145

British Geological Survey NATURAL ENVIRONMENT llESEARCH COUNCIL

..

This product includes mapping data licensed from Ordnance Survey. ©Crown Copyright and/or database right 2017. Licence number 100021290 EUL Scale: 1:5 000 (1cm = 50 m)

Contains Ordnance Survey data ©Crown Copyright and database right 2017 OS Street View: Scale: 1:5 000 (1cm = 50 m)

Date: 26 May 2017 © NERC, 2017. All rights reserved.

Site Address: VEOLIA,L/NG HALL QUARRY, COALPIT LANE, LAWFORD HEATH, RUGBY, CV23 9HH,GB

Point centred at: grid reference obtained from Ordnance Survey AddressPoint

Search location indicated in red

Page: 2 of25 BGS Report No: GR_ 216084/ 1

British Geological Survey NATUAAL EN VIR ONMENT AES EAR.CH COUNCIL

Assessment for an infiltration sustainable drainage system

Introduction

Sustainable drainage systems (SuDS) are drainage solutions that manage the volume and quality of surface water close to where it falls as rain. They aim to reduce flow rates to rivers, increase local water storage capacity and reduce the transport of pollutants to the water environment. There are four main types of SuDS, which are often designed to be used in sequence. They comprise:

o source control: systems that control the rate of runoff

o pre-treatment: systems that remove sediments and pollutants

o retention: systems that delay the discharge of water by providing surface storage

o infiltration: systems that mimic natural recharge to the ground.

This report focuses on infiltration SuDS. It provides subsurface information on the properties of the ground with respect to drainage, ground stability and groundwater quality protection. It is intended principally for those involved in the preliminary assessment of the suitability of the ground for infiltration SuDS, and those involved in assessing proposals from others for sustainable drainage, but it may also be useful to help house-holders judge whether or not further professional advice should be sought. If in doubt, users should consult a suitably-qualified professional about the results in this report before making any decisions based upon it.

This GeoReport is structured in two parts:

o Part 1. Summary data.

Comprises three maps that summarise the data contained within Part 2.

o Part 2. Detailed data.

Comprises a further 24 maps in four thematic sections:

o Very significant constraints. Maps highlight areas where infiltration may result in adverse impacts due to factors including: ground instability (soluble rocks, non-coal shallow mining and landslide hazards); persistent shallow groundwater, or the presence of made ground, which may represent a ground stability or contamination hazard.

o Drainage potential . Maps indicate the drainage potential of the ground, by considering subsurface permeability, depth to groundwater and the presence of floodplain deposits.

o Ground stability. Maps indicate the presence of hazards that have the potential to cause ground instability resulting in damage to some buildings and structures, if water is infiltrated to the ground.

o Groundwater protection. Maps provide key indicators to help determine whether the groundwater may be susceptible to deterioration in quality as a result of infiltration.

Date: 26 May 2017 Page: 3 of 25 © NERC, 2017. All rights reserved. BGS Report No: GR_ 21608411

British Geological Survey NATURAL ENVIRONMENT RESEARCH COUNCIL

This report considers the suitability of the subsurface for the installation of infiltration SuDS, such as soakaways, infiltration basins or permeable pavements. It provides subsurface data to indicate whether, and which type of infiltration system may be appropriate. It does not state that infiltration SuDS are, or are not, appropriate as this is highly dependent on the design of the individual system. This report therefore describes the subsurface conditions at the site, allowing the reader to determine the suitability of the site for infiltration SuDS.

The map and text data in this report is similar to that provided in the 'Infiltration SuDS Map: Detailed' national map product. For further information about the data, consult the 'User Guide for the Infiltration SuDS Map: Detailed', available from http://nora.nerc.ac.uk/16618/.

Date: 26 May 2017 Page: 4 of 25 © NERC, 2017. All rights reserved. BGS Report No: GR_216084/ 1

British Geological Survey NATURAL ENVIRONHENT RESEARCH COUNCIL

PART 1: SUMMARY DATA This section provides a summary of the data on the following pages. In terms of the drainage potential, is the ground suitable for infiltration SuDS?

· ·;,or~ , D Highly compatible for infiltration SuDS.

·~ The subsurface is likely to be suitable for free-draining

© Crown Copyright and/or database right 2017. All rights reserved. Licence number 100021290 EUL

infiltration SuDS.

D Probably compatible for infiltration SuDS.

The subsurface is probably suitable although the design may be influenced by the ground conditions.

II Opportunities for bespoke infiltration SuDS.

The subsurface is potentially suitable although the design will be influenced by the ground conditions.

D Very significant constraints are indicated.

There is a very significant potential for one or more hazards associated with infiltration.

Is ground instability likely to be a problem?


D Increased infiltration is very unlikely to result in ground instability.

D Ground instability problems may be present or anticipated, but increased infiltration is unlikely to result in ground instability

II Ground instability problems are probably present. Increased infiltration may result in ground instability.

D There is a very significant potential for one or more geohazards associated with infiltration.

Is the groundwater susceptible to deterioration in quality?

.... \ ~\ ,, ,,



D The groundwater is not expected to be especially vulnerable to contamination.

D The groundwater may be vulnerable to contamination.

D

The groundwater is likely to be vulnerable to contaminants.

Made ground is present at the surface. Infiltration may increase the possibility of remobilising pollutants.

Page: 5 of 25 BGS Report No: GR_216084/ 1

British Geological Survey NATUllltAL ENVllltONHENT RESEAlllCH COUNCIL

PART 2: DETAILED DATA This section provides further information about the properties of the ground and will

help assess the suitability of the ground for infiltration Su OS.

Section 1. Very significant constraints Where maps are overlain by grey polygons, geological or hydrogeological hazards

may exist that could be made worse by infiltration. The following hazards are

considered:

• soluble rocks • landslides

• shallow mining

• shallow groundwater • made ground

For more information read 'Explanation of terms' at the end of this report.

Soluble rock hazard


Landslide hazard

© Crown Copyright and/or database right 201 7. All rights reserved. Licence number 100021290 EUL


D Very significant soluble rock hazard.

Soluble rocks are present with a very significant possibility of localised subsidence that could be initiated or made worse by infiltration. The site investigation should consider whether the potential for or the consequences of subsidence as a result of infiltration are significant.

D Very significant soluble rock hazards are not present; however this hazard may still need to be considered. See Part 3.

D Very significant landslide hazard.

Slope instability problems are almost certainly present and may be active. An increase in moisture content as a result of infiltration may cause the slope to fail. The site investigation should consider whether the potential for or the consequences of landslide as a result of infiltration are significant.

D Very significant landslide hazards are not present; however this hazard may still need to be considered. See Part 3.

Page: 6 of 25 SGS Report No: GR_216084/ 1

British Geological Survey N ATURAL ENVIRONMENT RESEA RCH C OUNCIL

Shallow mining hazard


D Very significant mining hazard.

Shallow mining is likely to be present with a very significant possibility of localised subsidence that could be initiated or made worse by increased infiltration. Also, infiltration may increase the possibility of remobilising pollutants. The site investigation should consider whether the potential for or consequences of subsidence and/or remobilisation of pollutants as a result of infiltration are significant.

D Very significant mining hazards are not present; however this hazard may still need to be considered. See Part 3.

Persistent shallow groundwater

©Crown Copyright and/or database right 2017. All rights reserved. Licence number 100021290 EUL

Made ground



D Very high likelihood of persistent or seasonally shallow groundwater.

Persistent or seasonally shallow groundwater is likely to be present. Infiltration may increase the likelihood of soakaway inundation, or groundwater emergence at the surface. The site investigation should consider whether the potential for or the consequences of groundwater level rise as a result of infiltration are significant.

D See Part 2 for the likely depth to water table.

D Made ground present.

Made ground is present at the surface. Infiltration may affect ground stability or increase the possibility of remobilising pollutants. The site investigation should consider whether the potential for or consequences of ground instability and/or pollutant leaching as a result of infiltration are significant.

D None recorded

Page : 7 of 25 BGS Report No: GR_216084/ 1


Section 2. Drainage potential

The following pages contain maps that will help you assess the drainage potential of

the ground by considering the:

• depth to water table

• permeability of the superficial deposits

• thickness of the superficial deposits

• permeability of the bedrock

• presence of floodplains

Superficial deposits are not present everywhere and therefore some areas of the

superficial deposit permeability map may not be coloured. Where this is the case, the

bedrock permeability map shows the likely permeability of the ground. Superficial

deposits in some places are very thin and hence in these places you may wish to

consider both the permeability of the superficial deposits and the permeability of the

bedrock. The superficial thickness map will tell you whether the superficial deposits

are thin(< 3 m thick) or thick (>3 m). Where they are over 3 m thick, the permeability

of the bedrock may not be relevant.


Depth to groundwater table



D Groundwater is likely to be more than 5 m below the ground surface throughout the year.

D Groundwater is likely to be between 3 and 5 m below the ground surface for at least part of the year.

II Groundwater is likely to be less than 3 m below the ground surface for at least part of the year.

Page: 8 of 25 . BGS Report No: GR_216084/ 1

British Geological Survey NATURAL ENVtRONHENT RESEARCH COUNCIL

Superficial deposit permeability


These maps show the permeability range that is summarised above.

Overy Low DLow D Moderate

DHigh EJ Very High

Superficial deposit thickness


Date: 26 May 201 7 © NERC, 2017. All rights reserved.

D Superficial deposits are likely to be free-draining.

D The superficial deposit permeability is spatially variable, but likely to permit moderate infiltration.

II Superficial deposits are likely to be poorly draining.

Minimum



D The thickness of superficial deposits is < 3 m and hence the permeability of the ground may be dependent on both the superficial deposits (where present) and underlying bedrock (see below).

II The thickness of superficial deposits is > 3 m and hence the permeability of the superficial deposits is likely to determine the permeability of the ground.

Page: 9 of 25 BGS Report No: GR_ 216084/ 1

British Geological Survey NATURAL ENVIRONHENT 1u:sEA9'CH COUNCIL

Bedrock permeability


These maps show the permeability range that is summarised above.

Key

Overy Low DLow D Moderate DHigh Overy High

D Bedrock deposits are likely to be free-draining.

D The bedrock permeability is spatially variable, but likely to permit moderate infiltration.

II Bedrock deposits are likely to be poorly draining.

Minimum



Geological indicators of flooding



II Superficial floodplain deposits or low-lying coastal areas have been identified. Groundwater levels may rise in response to high river or tide levels, potentially causing inundation of subsurface infiltration SuDS.

Page: 1 O of 25 BGS Report No: GR_ 216084/ 1

British Geological Survey NATURAL ENVlltONHENT AESEAACH COUNCIL

Section 3. Ground stability

The following pages contain maps that will help you assess whether infiltration may

impact the stability of the ground. They consider hazards associated with :

• soluble rocks

• landslides

• shallow mining

• running sands

• swelling clays

• compressible ground, and

• collapsible ground

In the following maps, geohazards that are identified in green are unlikely to prevent

infiltration SuDS from being installed, but they should be considered during design.


Soluble rocks



D Increased infiltration is unlikely to result in subsidence.

D Increased infiltration is unlikely to cause localised subsidence, but potential impacts should be considered.

II Increased infiltration may result in localised subsidence. The potential for or the consequences of subsidence associated with soluble rocks should be considered.

D Very significant possibility of localised subsidence that cou ld be initiated or made worse by infiltration.

Page: 11 of 25 BGS Report No: GR_ 216084/1


Landslides


Shallow mining


Running sand


Date : 26 May 2017 © NERC, 2017. All rights reserved.

D Increased infiltration is unlikely to lead to slope instability.

D Slope instability problems may be present or anticipated, but increased infiltration is unlikely to cause instability

Ill Slope instability problems are probably present or have occurred in the past, and increased infiltration may result in slope instability.

D Slope instability problems are almost certainly present and may be active. An increase in moisture content as a result of infiltration may cause the slope to fail.

D Increased infiltration is unlikely to lead to subsidence.

D Shallow mining is possibly present. Increased infiltration is unlikely to cause a geohazard, but potential impacts should be considered.

II Shallow mining could be present with a significant possibility that localised subsidence could be initiated or made worse by increased infiltration.

D Shallow mining is likely to be present, with a very significant possibility that localised subsidence may be initiated or made worse by increased infiltration.

D Increased infiltration is unlikely to cause ground collapse associated with running sands.

D Running sand is possibly present. Increased infiltration is unlikely to cause a geohazard, but potential impacts should be considered.

Significant possibility for running sand problems. Increased infiltration may result in a geohazard.

Page: 12 of 25 BGS Report No: GR_ 216084/ 1


Swelling clays


Compressible ground


Collapsible ground



D Increased infiltration is unlikely to cause shrink-swell ground movement.

D Ground is susceptible to shrink-swell ground movement. Increased infiltration is unlikely to cause a geohazard, but potential impacts should be considered.

II Ground is susceptible to shrink-swell ground movement. Increased infiltration may result in a geohazard.

D Increased. infiltration is unlikely to lead to ground compression.

II Compressibility and uneven settlement hazards are probably present. Increased infiltration may result in a geohazard.

D Increased infiltration is unlikely to result in subsidence.

D Deposits with potential to collapse when loaded and saturated are possibly present in places. Increased infiltration is unlikely to cause a geohazard, but potential impacts should be considered.

II Deposits with potential to collapse when loaded and saturated are probably present in places. Increased infiltration may result in a geohazard.


British Geological Survey NATURAL ENVt RONHENT RESEARCH COUNCIL

Section 4. Groundwater quality protection

The following pages contain maps showing some of the information required to

ensure the protection of groundwater quality. Data presented includes:

• groundwater source protection zones (Environment Agency data)

• predominant flow mechanism

• made ground


Groundwater source protection zones

D Groundwater is not within a source protection zone.

" ·' l1 ' ~

D t Source protection zone IV / "" ,

-~ ~\'.\ d1 D Source protection zone Il l \ " I>.' r;i

'~. D Source protection zone II ?7?t::.rn ~

.... D Source protection zone I.

AAAJ:;nn :ui:;nnn ©Crown Copyright and/or database right 2017. All rights reserved. Licence number 100021290 EUL

Derived in part from Source Protection Zone data provided under licence from the Environment Agency© Environment Agency 2017.

Predominant flow mechanism "< ' D Water is likely to percolate through the unsaturated

' ~~ '!'> ( II~ \\ zone to the groundwater through either the pore space \\ u ?00

?7~nrn /f / in granular media or through porespace and fractures; •' '\

J-these processes have some potential for contaminant

~ A~~' - removal and breakdown.

D Water is likely to percolate through the unsaturated ,, , zone to the groundwater through fractures, a process

·~ which has little potential for contaminant removal and

~A A.r::.nn AA.t::.nnn breakdown. ©Crown Copyright and/or database right 201 7. All rights reserved. Licence number 100021290 EUL

Date: 26 May 2017 Page: 14 of 25 © NERC, 2017. All rights reserved. BGS Report No: GR_216084/1

British Geological Survey NATURAL ENVIRONMENT lltESEARCH COUNCIL

Made ground



D Made ground is present at the surface. Infiltration may increase the possibility of remobilising pollutants.


British Geological Survey NATUl'A.L ENVI RON'1ENT AESEA.RCH COUNCIL

Section 5. Geological Maps

The following maps show the artificial, superficial and bedrock geology within the area of interest.


---- Fault

----


Coal, ironstone or mineral vein

Bedrock

Note: Faults and Coals, ironstone & mineral veins are shown for illustration and to aid interpretation of the map. Not all such features are shown and their absence on the map face does not necessarily mean that none are present

Key to Artificial deposits: No deposits recorded by BGS in the search area

K t S ey o upe rfi . I d 1c1a epos1 s:

Map colour Computer Rock name Rock type Code

D BOSW-XCZ BOSWORTH CLAY MEMBER CLAY AND SILT

D DMG-XSV DUNSMORE GRAVEL SAND AND GRAVEL



K t B d k ey o e roe geo oov:

Map colour Computer Rock name Rock type Code

D CHAM-MOST CHARMOUTH MUDSTONE MUDSTONE

FORMATION

D RLS-MDLM RUGBY LIMESTONE MEMBER MUDSTONE AND LIMESTONE, INTERBEDDED

D SASH-MOST SAL TFORD SHALE MEMBER MUDSTONE


British Geological Survey NATURAL ENVIRONMENT flESEARC H COUNCIL

Limitations of this report:

• This report is concerned with the potentia l for infiltration-to-the-ground to be used as a SuDS technique at the site described. It only considers the subsurface beneath the search area and does NOT consider potential surface or subsurface impacts outside of that area.

• This report is NOT an alternative for an on-site investigation or soakaway test, which might reach a different conclusion.

• This report must NOT be used to justify disposal of foul waste or grey water.

• This report is based on and limited to an interpretation of the records held by the British Geological Survey (BGS) at the time the search is performed. The datasets used (with the exception of that showing depth to water table) are based on 1 :50 000 digital geological maps and not site-specific data.

• Other more specific and detailed ground instability information for the site may be held by BGS, and an assessment of this could result in a modified assessment.

• To interpret the maps correctly, the report must be viewed and printed in colour.

• The search does NOT consider the suitability of sites with regard to: o previous land use, o potential for, or presence of contaminated land o presence of perched water tables o shallow mining hazards relating to coal mining . Searches of coal min ing

should be carried out via The Coal Authority Mine Reports Service: www.coalminingreports.co.uk.

o made ground, where not recorded o proximity to landfill sites (searches for landfill sites or contaminated land

should be carried out through consultation with local authorities/Environment Agency)

o zones around private water supply boreholes that are susceptible to groundwater contamination.

• This report is supplied in accordance with the GeoReports Terms & Conditions available separately, and the copyright restrictions described at the end of this report


British Geological Survey NATURAL ENVUlONHENT RESEARCH COUNCIL

Explanation of terms

Depth to groundwater In the shallow subsurface, the ground is commonly unsaturated with respect to water. Air fills the spaces within the soil and the underlying superficial deposits and bedrock. At some depth below the ground surface, there is a level below which these spaces are full of water. This level is known as the groundwater level, and the water below it is termed the groundwater. When water is infiltrated, the groundwater level may rise temporarily. To ensure that there is space in the unsaturated zone to accommodate this, there should be a minimum thickness of 1 m between the base of the infiltration system and the water table. An estimate of the depth to groundwater is therefore useful in determining whether the ground is suitable for infiltration.

Groundwater flooding Groundwater flooding occurs when a rise in groundwater level results in very shallow groundwater or the emergence of groundwater at the surface. If infiltration systems are installed in areas that are susceptible to groundwater flooding, it is possible that the system could become inundated. The susceptibility map seeks to identify areas where the geological conditions and water tables indicate that groundwater level rise could occur under certain circumstances. A high susceptibility to groundwater flooding classification does not mean that groundwater flooding has ever occurred in the past, or will do so in the future as the susceptibility maps do not contain information on how often flooding may occur. The susceptibility maps are designed for planning; identifying areas where groundwater flooding might be an issue that needs to be taken into account.


British Geological Survey NATURAL ENVIRON MENT RESEARCH COUNCtl

Geological indicators of flooding In floodplain deposits, groundwater level can be influenced by the water level in the adjacent river. Groundwater level may increase during periods of fluvial flood and therefore this should be taken into account when designing infiltration systems on such deposits. The geological indicators of flooding dataset shows where there is geological evidence (floodplain deposits) that flooding has occurred in the past.

For further information on flood-risk, the likely frequency of its recurrence in relation to any proposed development of the site, and the status of any flood prevention measures in place, you are advised to contact the local office of the Environment Agency (England and Wales) at www.environment-agency.gov.uk/ or the Scottish Environment Protection Agency (Scotland) at www.sepa.org.uk.

Artificial ground Artificial ground comprises deposits and excavations that have been created or modified by human activity. It includes ground that is worked (quarries and road cuttings), infilled (back-filled quarries), landscaped (surface re-shaping), disturbed (near surface mineral workings) or classified as made ground (embankments and spoil heaps). The composition and properties of artificial ground are often unknown. In particular, the permeability and chemical composition of the artificial ground should be determined to ensure that the ground will drain and that any contaminants present will not be remobilised.

Superficial permeability Superficial deposits are those geological deposits that were formed during the most recent period of geological time (as old as 2.6 million years before present). They generally comprise relatively thin deposits of gravel, sand, silt and clay and are present beneath the pedological soil in patches or larger spreads over much of Britain. The ease with which water can percolate through these deposits is controlled by their permeability and varies widely depending on their composition. Those deposits comprising clays and silts are less permeable and thus infiltration is likely to be slow, such that water may pool on the surface. In comparison, deposits comprising sands and gravels are more permeable allowing water to percolate freely.

Bedrock permeability Bedrock forms the main mass of rock forming the Earth. It is present everywhere, commonly beneath superficial deposits. Where the superficial deposits are thin or absent, the ease with which water will percolate into the ground depends on the permeability of the bedrock.

Date: 26 May 2017 Page: 20 of 25 © NERC, 2017. All rights reserved. BGS Report No : GR_216084/ 1

British Geological Survey NATURAL ENV IRONM ENT ft ES EAR.CH COUNCIL

Natural ground instability Natural ground instability refers to the propensity for upward, lateral or downward movement of the ground that can be caused by a number of natural geological hazards (e.g. ground dissolution/compressible ground). Some movements associated with particular hazards may be gradual and of millimetre or centimetre scale, whilst others may be sudden and of metre or tens of metres scale. Significant natural ground instability has the potential to cause damage to buildings and structures, especially when the drainage characteristics of a site are altered. It should be noted, however, that many buildings, particularly more modern ones, are built to such a standard that they can remain unaffected in areas of significant ground movement.

Shrink-swell A shrinking and swelling clay changes volume significantly according to how much water it contains. All clay deposits change volume as their water content varies, typically swelling in winter and shrinking in summer, but some do so to a greater extent than others. Contributory circumstances could include drought, leaking service pipes, tree roots drying-out the ground or changes to local drainage patterns, such as the creation of soakaways. Shrinkage may remove support from the foundations of buildings and structures, whereas clay expansion may lead to uplift (heave) or lateral stress on part or all of a structure; any such movements may cause cracking and distortion.

Landslides (slope stability) A landslide is a relatively rapid outward and downward movement of a mass of ground on a slope, due to the force of gravity. A slope is under stress from gravity but will not move if its strength is greater than this stress. If the balance is altered so that the stress exceeds the strength, then movement will occur. The stability of a slope can be reduced by removing ground at the base of the slope, by placing material on the slope, especially at the top, or by increasing the water content of the materials forming the slope. Increase in subsurface water content beneath a soakaway could increase susceptibility to landslide hazards. The assessment of landslide hazard refers to the stability of the present land surface. It does not encompass a consideration of the stability of excavations.

Soluble rocks (dissolution) Some rocks are soluble in water and can be progressively removed by the flow of water through the ground. This process tends to create cavities, potentially leading to the collapse of overlying materials and possibly subsidence at the surface. The release of water into the subsurface from infiltration systems may increase the dissolution of rock or destabilise material above or within a cavity. Dissolution cavities may create a pathway for rapid transport of contaminated water to an aquifer or water course.


British Geological Survey N AT URAL EN VIRONM EN T RESEARCH COUNCtl

Compressible ground Many ground materials contain water-filled pores (the spaces between solid particles). Ground is compressible if a building (or other load) can cause the water in the pore space to be squeezed out, causing the ground to decrease in thickness. If ground is extremely compressible the building may sink. If the ground is not uniformly compressible , different parts of the building may sink by different amounts, possibly causing tilting, cracking or distortion. The compressibility of the ground may alter as a result of changes in subsurface water content caused by the release of water from soakaways.

Collapsible deposits Collapsible ground comprises certain fine-grained materials with large pore spaces (the spaces between solid particles). It can collapse when it becomes saturated by water and/or a building (or other structure) places too great a load on it. If the material below a building collapses it may cause the building to sink. If the collapsible ground is variable in thickness or distribution, different parts of the building may sink by different amounts, possibly causing tilting, cracking or distortion. The subsurface underlying a soakaway will experience an increase in water content that may affect the stability of the ground. This hazard is most likely to be encountered only in parts of southern England.

Running sand Running sand conditions occur when loosely-packed sand, saturated with water, flows into an excavation, borehole or other type of void. The pressure of the water filling the spaces between the sand grains reduces the contact between the grains and they are carried along by the flow. This can lead to subsidence of the surrounding ground. Running sand is potentially hazardous during the drainage system installation. During installation, excavation of the ground may create a space into which sand can flow, potentially causing subsidence of surrounding ground.

Shallow mining hazards (non coal) Current or past underground mining for coal or for other commodities can give rise to cavities at shallow or intermediate depths, which may cause fracturing, general settlement, or the formation of crown-holes in the ground above. Spoil from mineral workings may also present a pollution hazard. The release of water into the subsurface from soakaways may destabilise material above or within a cavity. Cavities arising as a consequence of mining may also create a pathway for rapid transport of contaminated water to an aquifer or watercourse. The mining hazards map is derived from the geological map and considers the potential for subsidence associated with mining on the basis of geology type. Therefore if mining is known to occur within a certain rock, the map will highlight the potential for a hazard w ithin the area covered by that geology.


British Geological Survey N ATU llt AL EN VI RO NMEN T RESEA RC H COUN CIL

For more information regarding underground and opencast coal mining, the location of mine entries (shafts and adits) and matters relating to subsidence or other ground movement induced by coal mining please contact the Coal Authority, Mining Reports, 200 Lichfield Lane, Mansfield, Nottinghamshire, NG18 4RG; telephone 0845 762 6848 or at www.coal.gov.uk. For more information regarding other types of mining (i.e. non

coal), please contact the British Geological Survey.

Groundwater source protection zones In England and Wales, the Environment Agency has defined areas around wells, boreholes and springs that are used for the abstraction of public drinking water as source protection zones. In conjunction with Groundwater Protection Policy the zones are used to restrict activities that may impact groundwater quality, thereby preventing pollution of underlying aquifers, such that drinking water quality is upheld. The Environment Agency can provide advice on the location and implications of source protection zones in your area (www.environment-agency.gov.uk/)


British Geological Survey NATURAL ENVIRONM ENT ftE SEARCH COUNCIL

Contact Details

Keyworth Office British Geological Survey Environmental Science Centre Nicker Hill Keyworth Nottingham NG12 5GG Tel: 0115 9363143 Fax: 0115 9363276 Email: [email protected]

Wallingford Office British Geological Survey Maclean Building Wallingford Oxford OX10 8BB Tel: 01491 838800 Fax: 01491 692345 Email: [email protected]

Edinburgh Office British Geological Survey Lyell Centre Research Avenue South Edinburgh EH14 4AP Tel: 0131 6671000 Email: [email protected]



British Geological Survey NATUl'lAL ENVIRONMENT RESEARCH COUNCIL

Terms and Conditions General Terms & Conditions

This Report is supplied in accordance with the GeoReports Terms & Conditions available on the BGS website at https://shop.bQs.ac.uk/georeports and also available from the BGS Central Enquiries Desk at the above address.

Important notes about th is Report

The data, information and related records supplied in this Report by BGS can only be indicative and should not be taken as a substitute for specialist interpretations, professional advice and/or detailed site investigations. You must seek professional advice before making technical interpretations on the basis of the materials provided.

• Geological observations and interpretations are made according to the prevailing understanding of the subject at the time. The quality of such observations and interpretations may be affected by the availability of new data, by subsequent advances in knowledge, improved methods of interpretation, and better access to sampling locations.

• Raw data may have been transcribed from analogue to digital format, or may have been acquired by means of automated measuring techniques. Although such processes are subjected to quality control to ensure reliability where possible, some raw data may have been processed without human intervention and may in consequence contain undetected errors.

• Detail , which is clearly defined and accurately depicted on large-scale maps, may be lost when small-scale maps are derived from them.

• Although samples and records are maintained with all reasonable care, there may be some deterioration in the long term.

The most appropriate techniques for copying original records are used, but there may be some loss of detail and dimensional distortion when such records are copied.

Data may be compiled from the disparate sources of information at BGS's disposal, including material donated to BGS by third parties, and may not originally have been subject to any verification or other quality control process.

Data, information and related records, which have been donated to BGS, have been produced for a specific purpose, and that may affect the type and completeness of the data recorded and any interpretation. The nature and purpose of data collection , and the age of the resultant material may render it unsuitable for certain applications/uses. You must verify the suitability of the material for your intended usage.

• If a report or other output is produced for you on the basis of data you have provided to BGS, or your own data input into a BGS system, please do not rely on it as a source of information about other areas or geological features, as the report may omit important details.

• The topography shown on any map extracts is based on the latest OS mapping and is not necessarily the same as that used in the original compilation of the BGS geological map, and to which the geological linework available at that time was fitted.

• Note that for some sites, the latest available records may be quite historical in nature, and while every effort is made to place the analysis in a modern geological context, it is possible in some cases that the detailed geology at a site may differ from that described.

Copyright: Copyright in materials derived from the British Geological Survey's work, is owned by the Natural Environment Research Council (NERC) and/ or the authority that commissioned the work. You may not copy or adapt this publication, or provide it to a third party, without first obtaining NERC's permission, but if you are a consultant purchasing this report solely for the purpose of providing advice to your own individual client you may incorporate it unaltered into your report to that client without further permission, provided you give a full acknowledgement of the source. Please contact the BGS Copyright Manager, British Geological Survey, Environmental Science Centre, Nicker Hill , Keyworth, Nottingham NG12 5GG. Telephone: 0115 936 3100. © NERC 2017 All rights reserved .

This product includes mapping data licensed from the Ordnance Survey® with the perm1ss1on of the Controller of Her Majesty's Stationery Office. © Crown Copyright 2017. All rights reserved. Licence number 100021290 EUL

-~~Ordna~ · .. · ~!::d Survey

Report issued by BGS Enquiry Service



2 June 2017 Report No. 173593.500.A0

APPENDIX D Drawings

118.25

118.27

120.06

121.16

122.12

122.51

121.33

122.93

118.01

117.37

110.46

PV1PV2

PV3

PV4

POND A

POND B

POND E

EXISTINGWETLAND

EXISTINGWETLAND

TOPSOIL

GRASS WITHIN SWALE TOBE SEEDED UNLESS EARLYEROSION CONTROL ISREQUIRED IN WHICH CASETURF SHOULD BE USED

RUNOFF

EDGE OFCONTAINMENTLANDFILL

LANDFILL SIDEWALLLINING SYSTEM

IN-SITU SANDAND GRAVEL

MIN0.65 m

MIN 1 mMIN 2.6 m

MIN

1 m

41

41

GROUNDWATER TABLEIN SAND AND GRAVEL

TYPICAL SWALE/CHANNEL CROSS SECTION

025

mm

1773596CONTROL1001-LH-0001

DRAWING

1A

YYYY-MM-DD

ECS

MG

MG

FB

SURFACE DRAINAGE STRATEGYREG LING HALL SOLAR LTD

PLANNING CONDITION DISCHARGE TITLE

PROJECT NO. REV.

PROJECTCLIENT

CONSULTANT

DESIGNED

PREPARED

REVIEWED

APPROVED

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No. PVCELLS

PV1 15.06 297

PV2 9.52 187

PV3 6.30 126

PV4 10.88 485

RED LINE BOUNDARY

PHOTOVOLTAIC CELL

LEGEND

INDICATIVE ATTENUATION AND SOAKAWAY AREAS

OPEN WATER CHANNELS AND INDICATIVE FLOW DIRECTION - (SLR,2017)

Golder Associates (UK) Ltd

Sirius Building, The Clocktower

South Gyle Crescent

Edinburgh

EH12 9LB

UK

T: [+44] (0) 131 314 5900

Caption Text

surface drainage strategy

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