Proposed Residential Development at Church Road, Killiney...

Proposed Residential Development at

Church Road, Killiney, Co. Dublin

Stage 1 Surface Water Audit

June 2019

Proposed Residential Development at Church Road,

Killiney, Co. Dublin


192201-PR0 Page i June 2019

Document Control

Document Number: 192-201-PR0

Revision Date Prepared Checked Approved

PR0 12.06.2019

K.O.Kelly

Design Engineer

Civil-Engineering

Management–Bsc

(Hons)

C. O’Shea

Senior Engineer

MSc BSc (Hons)

MCIWEM

D. Gallery

Technical Director

BEng (Hons) PGDipHSC

MIEI MIOSH

PR1 21.06.2019

K.O.Kelly

Design Engineer

Civil-Engineering

Management–Bsc

(Hons)

C. O’Shea

Senior Engineer

MSc BSc (Hons)

MCIWEM

D. Gallery

Technical Director

BEng (Hons) PGDipHSC

MIEI MIOSH

Report by: ______________________ Date: 12th June 2019

Kevin O Kelly

Design Engineer

PUNCH Consulting Engineers

Checked by: ______________________ Date: 12th June 2019

Ciaran O’Shea

Senior Engineer


Approved by: ______________________ Date: 12th June 2019

Donal Gallery

Technical Director





192201-PR0 Page ii June 2019

Table of Contents

Document Control ......................................................................................................... i

Table of Contents ......................................................................................................... ii

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

1.1 Purpose of Report .............................................................................................1

1.2 Site Details .....................................................................................................1

1.3 Report Details ..................................................................................................1

2 Stage 1 Audit Findings ...........................................................................................2

2.1 Church Road, Killiney .........................................................................................2

2.1.1 Filter Drains/Bio-Retention ...............................................................................2

2.1.2 Proposed Permeable Paving System .....................................................................2

2.1.3 Ponds .........................................................................................................2

2.1.4 Roads surfacing/Porous Asphalt .........................................................................3

2.1.5 Bypass Interceptor .........................................................................................3

2.1.6 Attenuation Storage Tanks ................................................................................3

2.1.7 Attenuation Storage Tank mitigation measures against flotation .................................3

2.1.8 Sump Manholes ..............................................................................................3

2.1.9 Road Gullies/Tree Pits .....................................................................................4

2.1.10 Water Table ..............................................................................................4

2.1.11 Typical Swale Details – Permeable Liner ............................................................4

2.1.12 Typical Details ...........................................................................................4

2.1.13 Utility Survey .............................................................................................5

2.1.14 Existing Natural Features on Site .....................................................................5

2.1.15 Gradients and ground modelling ......................................................................5

2.1.16 Hydrobrake ...............................................................................................5

2.2 Buildings/Residential Units ..................................................................................6

2.2.1 Green Roofs .................................................................................................6

2.2.2 Rainwater Harvesting Tanks ..............................................................................6

Appendix A Drawings and Documents Examined by the Auditor ............................................. A-I

Appendix B Site Layout with Stage 1 Audit Findings Highlighted ............................................ B-I

Appendix C Storm Water Audit Feedback Form .................................................................C-I




192221-PR0 1 June 2019

1 Introduction

1.1 Purpose of Report

This report presents a Stage 1 Surface Water Audit carried out for a proposed Residential development

and associated infrastructure at Church Road, Killiney, Co. Dublin. DBFL Engineers have carried out the

design for this development. The pre-panning file application number for this development is PAC SHD

17 19.

1.2 Site Details

The proposed Residential development site area is approximately 1.485 hectares. The existing site is

predominately undeveloped with three disused residences within the property which are to be

demolished as part of the new site works. The site is bordered by existing residential properties north

and west of the site with a school and church to the south/west of the site. On the north/east of the

site there is the Graduate Roundabout on the Church road. The land generally falls from the north to the

south at a gradient of approximately 1 in 25 across the site. The proposed road levels within the area

range from 49.27m to 50.0m OD Malin. The proposed residential finished floor level on site ranges from

53.1m to 53.5m OD Malin. The new development will consist of 210 no. units to be provided as follows:

• 27 no. 1 bed apartments



1.3 Report Details

The audit was carried out by Kevin O Kelly, Ciaran O Shea and Donal Gallery between the dates of June

6th and June 12th 2019.

This Stage 1 Audit has been carried out in accordance with the Dún Laoghaire-Rathdown County Council

(DLRCC) Stormwater Audit Procedure Rev 0 January 2012. The auditor has examined only those issues

within the design relating to surface water drainage implications of the scheme and has therefore not

examined or verified the compliance of the design to any other criteria.

Appendix A contains copies of drawings and documents examined by the auditor. The drawings in

Appendix B correspond to the Stage 1 Audit findings outlined in Section 2 of this report. Appendix C

contains the Surface Water Audit Feedback form.

All of the findings outlined in Section 2 of this report are considered by the auditor to require action in

order to improve the stormwater credentials of the scheme.




192221-PR0 2 June 2019

2 Stage 1 Audit Findings

2.1 Church Road, Killiney

2.1.1 Filter Drains/Bio-Retention

Problem: There is potential to reduce the surface water runoff directly to the surface water network,

to improve runoff quality, groundwater recharge and amenity opportunities by incorporating bio

retention systems or additional filter drains into the design.

Recommendation: Consider incorporating additional bio-retention systems or filter drains beyond the

road edge to increase infiltration and promote groundwater recharge in these areas before connection

to the surface water network. Details required on proposed filter drains design.

2.1.2 Proposed Permeable Paving System

Problem: It is not clear on the drawings provided whether there is geotextile as part of the permeable

paving system and furthermore is it suitable for hydrocarbon pollution treatment.

Recommendation: When utilising a permeable paving system, incorporating a geotextile with proven

capabilities for hydrocarbon pollution treatment in sustainable drainage systems (SuDS). The stone layer

within the build-up of the permeable system will have a dual effect of the cleaning the surface water

run-off from contaminants, and attenuating the flow, reducing the rate at which surface water would

flow from these areas. Please provide details on the purposed permeable.

2.1.3 Pond

Problem: There is potential to reduce the surface water runoff and to improve runoff quality from the

drainage output from the development by incorporating ponds.

Recommendation: Consider incorporating a pond instead of the water storage attenuation in catchment

A of the site. Incorporating a pond can provide both attenuation and treatment of surface water runoff.

It can support aquatic vegetation which further enhances the treatment process, enhances biodiversity

and offers aesthetic benefits to the site.




192221-PR0 3 June 2019

2.1.4 Roads surfacing/Porous Asphalt

Problem: The proposed roads surfacing has potential to increase the surface water runoff from the

development.

Recommendation: Consider utilising porous asphalt or porous concrete surfacing throughout the

development as a roads surfacing. This would allow surface water runoff from all areas subject to

vehicular traffic to achieve an enhanced environmental quality level as well as a greater opportunity for

infiltration.

2.1.5 Bypass Interceptor

Problem: Bypass Interceptor sizing details have not been included in the documents provided.

Recommendation: In drawing 180153-300 a Bypass Petrol interceptor is shown, can you provide details

on the proposed NSB010 to illustrate that it is the correct design for the catchment area.

2.1.6 Attenuation Storage Tanks

Problem: In drawing 180153-3000 there is two storage tanks shown. Is it possible to move the storage

tank out of catchment A into an area where flotation would not be an issue? Alternatively, if this is not

feasible it may be possible to incorporate a storage pond into this area as per comment 2.1.3.

Recommendation: Can details be provided on the water storage tanks.

2.1.7 Attenuation Storage Tank mitigation measures against flotation

Problem: It is noted that the attenuation tank will be partially constructed below the groundwater table.

The drawings provided indicate that a concrete slab be provided above the attenuation tank to mitigate

against flotation.

Recommendation: Please provide further details on the concrete slab over the attenuation tank. Will

this slab affect the structural stability of the attenuation tank?

2.1.8 Sump Manholes

Problem: Silt entering the surface water drainage system including the attenuation tanks has the

potential to cause blockages.

Recommendation: Consider utilisation of sump manholes upstream of both attenuation tanks to capture

any excess silt therefore preventing entry into the tanked systems.




192221-PR0 4 June 2019

2.1.9 Road Gullies/Tree Pits

Problem: There is potential to reduce the surface water runoff and to improve runoff quality from the

minor roads around the development by incorporating SuDS measures in lieu of road gullies.

Recommendation: In place of connecting the proposed gullies directly into the proposed surface water

network, consider connecting proposed gullies to a SuDS measure such as an infiltration drain, tree pits,

drainage ditch, bio-retention area, basin or soakaway with an overflow to the surface water network, as

a means to further reduce the quantity and improve the quality of surface water runoff from the site.

2.1.10 Water Table

Problem: Although no ground water is encountered, the hydrological report noted that the groundwater

flow follows the topography of the site and the monitoring wells suggest that the upgradient of the

proposed basements and attenuation structures will be partially constructed below the eater table. The

designer should ensure the formation level of the permeable paving is 1000mm above the highest ground

water level.

Recommendation: Consider further site investigation to ensure the ground water level is not less than

1000mm below the formation level of the permeable carpark build-up and attenuation tanks.

2.1.11 Typical Swale Details – Permeable Liner

Problem: Referring to drawing 180153-3000, there is no typical swale detail which specifies an

impermeable membrane or similar approved to be used below the topsoil substrate.

Recommendation: Consider incorporating a permeable liner for the swales, this will provide a more

efficient SuDS solution.

2.1.12 Typical Details

Problem: No details provided for proposed SuDS components including permeable paving, flow control

devices, swales, etc.

Recommendation: The above details to be provided.




192221-PR0 5 June 2019

2.1.13 Utility Survey

Problem: As per Chapter 29.3.6, Section E of The SuDS Manual, the location of all existing utilities and

other site infrastructure should be confirmed before locating proposed SuDS measures. In drawing

180153-3000 there appears to be an extensive topographical survey completed locating all above ground

services, no utility survey was undertaken as part of these works.

Recommendation: Existing underground services are particularly challenging to locate in construction

projects. Asset databases of buried infrastructure should not be considered as definite and should be

checked with appropriate utility surveys and on-site checks.

2.1.14 Existing Natural Features on Site

Problem: Existing natural features on site include trees, hedgerows, or habitats of ecological value. For

this proposed development, some of these features may potentially be affected.

Recommendation: Existing trees, hedgerows and habitats should be subject to pre-development surveys

in accordance with relevant standards and undertaken by a qualified and competent person. If required,

based on the relevant pre-development surveys, the construction of SuDS measures are to be co-

ordinated with the existing features of the site.

2.1.15 Gradients and ground modelling

Problem: As per Chapter 29.2, Section E of The SuDS Manual, successfully integrating SuDS measures

including swales, infiltration trenches and infiltration blankets require areas of ground modelling to

ensure proposed SuDS measures are located in appropriate areas to ensure adequate drainage of the site.

Recommendation: It is recommended that the integration of each SuDS component be considered, and

its contouring adjusted to allow the levels to flow towards to SuDS measure, in a naturalistic manner

that is visually attractive, and accords with the local surrounding landscape.

2.1.16 Hydrobrake

Problem: Provide additional details of the proposed Hydrobrake.

Recommendation: Please confirm that forward flow from both hydrobrake’s is a per the Greater Dublin

Strategic Drainage Strategy. Please also confirm size of hydrobrake orifice. We do not recommend use

of a flow control device with an orifice below 75mm diameter; and (b) the time of emptying of such a

large system will no doubt exceed the recommended duration of <24 hours to half empty after a storm

event.




192221-PR0 6 June 2019

2.2 Buildings/Residential Units

2.2.1 Green Roofs

Problem: Green roofs are proposed in drawing 180153-300 but they do not call off what type of green roof

is being used in each of the locations.

Recommendation: Where possible, consider changing the extensive green roof proposal to an intensive

green roof proposal, which would double as a roof garden. This would be in line with the philosophy of

SuDS providing additional benefits. The development’s end user would noticeably benefit from the addition

of intensive green roofs in the proposed development, as this would create additional useable spaces. This

also has the benefit of additional biodiversity potential.1

2.2.2 Rainwater Harvesting Tanks

Problem: In addition of utilising green roofs, there is potential to install a rainwater harvesting facilities

for the proposed units. The rainwater collected can be used for toilet flushing within the new units.

Recommendation: Consider incorporating rainwater harvesting tanks.




192221-PR0 A-I June 2019

Appendix A Drawings and Documents Examined by the Auditor

© COPYRIGHT OF THIS DRAWING IS RESERVED BY DBFLCONSULTING ENGINEERS. NO PART SHALL BE REPRODUCED ORTRANSMITTED WITHOUT THEIR WRITTEN PERMISSION.

ON ORIGINAL

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SCALE

DRG. NO.

FILE REF.

DRG. TITLE

PROJECT

REV. DATE DESCRIPTION BY CHKD.

DESIGNED

DATE

PREPARED

CHECKED

@A1

PLANNINGSVC

JUN 2019

KJL'E

PMF

PROPOSED RESIDENTIALDEVELOPMENT AT CHURCHROAD, KILLINEY, CO. DUBLIN

STANDARD DETAILSSHEET 3 OF 4

ARCHITECT

O'MAHONY PIKE ARCHITECTS

1:25 180153-3021

180153-3023 A

NOTE:ALL WORKS TO BE UNDERTAKEN INACCORDANCE WITH

· TII SPECIFICATION FORROADWORKS

· GREATER DUBLIN CODE OFPRACTICE FOR DRAINAGE WORKS

· RECOMMENDATIONS FOR SITEDEVELOPMENT WORKS

· IRISH WATER CODE OF PRACTICE


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DESIGNED

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@A1

PLANNINGSVC

JUN 2019

KJL'E

PMF


STANDARD SUDS DETAILSSHEET 1 OF 2

ARCHITECT


1:25 180153-3021

180153-3025 A


ON ORIGINAL

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DATE

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@A1

PLANNINGSVC

JUN 2019

KJL'E

PMF


STANDARD SUDS DETAILSSHEET 2 OF 2

ARCHITECT


1:25 180153-3021

180153-3026 A

NOTE:ALL WORKS & SPECIFICATIONS TO BE

UNDERTAKEN IN ACCORDANCE WITH· TII SPECIFICATION FOR

ROADWORKS· GREATER DUBLIN CODE OF

PRACTICE FOR DRAINAGE WORKS· RECOMMENDATIONS FOR SITE

DEVELOPMENT WORKS


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KJL'E

PMF


TYPICAL ROADCROSS-SECTIONS

ARCHITECT


1:25 180153-3021

180153-3027 A

SURFACE WATER CATCHMENT

VOLUME REQUIRED = 30.20m3

VOLUME PROVIDED = 13.5m3 *

MECHANISMS PERMEABLE PAVING, SWALES, GREEN ROOFS.

VOLUME REQUIRED = 90.50m3

VOLUME PROVIDED = 277.10m3 (+44.50m³ not included on SuDS summary calculation sheet)

REQUIRED No.OF STAGES

1st TREATMENT STAGE VOLUME PROV.ADDITIONAL TREATMENT

STAGEVOLUME PROV. COMPLIANCE

GREENROOFS

1 · GREEN ROOF 203.00m3 · PETROL INTERCEPTOR· ISOLATOR ROW

*ALL OK

ROOF TOTRADITIONAL

1 · ISOLATOR ROW 44.50m3 · PETROL INTERCEPTOR *ALL OK

ROADS +FOOTPATHS

TO SUDS2

· SWALES· PERMEABLE PAVING

74.10m3 · PETROL INTERCEPTOR· ISOLATOR ROW

*ALL OK

ROADS +FOOTPATHS

TO TRAD.2 · ISOLATOR ROW

ALREADYINCLUDED

· PETROL INTERCEPTOR *ALL OK

* VOLUME IS LOWER THAN REQUIRED DUE TO POOR INFILTRATION RATES

LEGEND:

ORDNANCE SURVEY IRELAND LICENCENo EN 0017919

© ORDNANCE SURVEY IRELANDGOVERNMENT OF IRELAND


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SCHEMATIC SUDS LAYOUTPLAN

ARCHITECT


1:500 180153-3070

180153-3070 .

N

S

EW

N

S

EW

Residential Development at Churchview Road, Killiney Dublin 18

DBFL Consulting Engineers 180153-rep-001

Engineering Services Report 1 May 2019

MAY 2019

Project

Residential Development at Churchview Road,

Killiney, Dublin 18

Report Title

Engineering Services Road




Job Title: Residential Development at Churchview Road, Killiney, Dublin

18

Report Title: Engineering Services Report

Job Number: p180153

Author: Laura McLoughlin

Checked by: Paul Forde

Date: May 2019

Distribution: Design Team

DBFL Consulting Engineers

DBFL Consulting Engineers Ormond House

Ormond Quay Upper

Dublin 7

Tel 01 4004000

Fax 01 4004050 Email [email protected]

Web www.dbfl.ie

Revision Issue Date Description Prepared Reviewed Approved

- 14 Mar 2019 Issued for Pre-Planning LMCL PMF PMF

A XX May 2019 Planning Submission LMCL SVC PMF

http://www.dbfl.ie/




TABLE OF CONTENTS

1. INTRODUCTION ........................................................................................................................................... 1

2. FOUL SEWERS ............................................................................................................................................... 3

2.1 EXISTING SERVICES .................................................................................................................................... 3 2.2 PROPOSED SERVICES ................................................................................................................................... 3

3. SURFACE WATER......................................................................................................................................... 6

3.1 EXISTING SERVICES .................................................................................................................................... 6 3.2 PROPOSED SERVICES ................................................................................................................................... 6

3.2.1 SuDS ................................................................................................................................................... 7 3.2.2 Long Term Storage............................................................................................................................. 9 3.2.3 Greenfield Runoff – Pre-Development ............................................................................................... 9 3.2.4 Surface Water Runoff Coefficients ....................................................................................................11 3.2.5 Surface Water Attenuation - Site Investigation .................................................................................11 3.2.6 Surface Water Attenuation - Design..................................................................................................12

3.2.7 Interception Volume ..........................................................................................................................14 3.2.8 Treatment Volume .............................................................................................................................15 3.2.9 Surface Water Sewers .......................................................................................................................16 3.2.10 Amenity .............................................................................................................................................17

3.2.11 SuDS Maintenance ............................................................................................................................17

4 WATERMAINS ..............................................................................................................................................19

4.1 EXISTING SERVICES ...................................................................................................................................19 4.2 PROPOSED SERVICES ..................................................................................................................................19

5 ROADS ............................................................................................................................................................20

6 FLOOD RISK ASSESSMENT ............................................................................................................................20

6.1 APPROACH .............................................................................................................................................20

6.2 PLANNING SYSTEM & FLOOD RISK MANAGEMENT GUIDELINES ............................................20

6.2.1 General .............................................................................................................................................20

6.2.2 Flood Risk Assessment Stages ...........................................................................................................20

6.3 FLOOD RISK IDENTIFICATION STAGE .............................................................................................21

6.3.1 General .............................................................................................................................................21

6.3.2 Information Sources Consulted .........................................................................................................21

6.3.3 Source-Pathway-Receptor Model .....................................................................................................22

6.3.4 Source-Pathway-Receptor Model Results .........................................................................................24

6.3.5 Mitigation Measures .........................................................................................................................24

6.3.6 Residual Risks ...................................................................................................................................25

6.4 CONCLUSION .........................................................................................................................................25

APPENDIX A - Existing Drainage Records

APPENDIX B - Irish Water Pre-Connection Enquiry Response

APPENDIX C – Foul Sewer Calculations

APPENDIX D - Permissible Discharge Calculations

APPENDIX E - Surface Water Attenuation Calculations

APPENDIX F - Surface Water Interception Volume Calculations

APPENDIX G - Surface Water Treatment Volume Calculations

APPENDIX H - SuDS Summary




APPENDIX I - Surface Water Sewers Calculations

APPENDIX J – Watermain Calculations

APPENDIX K – Ground Investigation Report

APPENDIX L – Phase 1 Hydrogeological Site Assessment

APPENDIX M – Surcharge Analysis and Corresponding Microdrainage Results

APPENDIX N – Technical Note 180183/002




1. INTRODUCTION

This report relates to a proposed residential development at Churchview Road, Killiney, Dublin

18.

The existing site is mostly undeveloped with three disused residences located thereon which are

proposed to be demolished to facilitate the subject proposals. The site is bordered to the

northeast by Church Road and ‘the Graduate Roundabout’, on the southeastern boundary there

is an existing row of 8 houses, known as Fairhaven, fronting on to Churchview Road. There are

existing detached properties to the north and north-west and there are playing fields on the

southwestern boundary.

The site slopes at an approximate gradient of 1 in 25 from north-east to south-west away from

Church Road.

The associated site and infrastructural works include foul and surface water drainage, water

supply, internal roads and footpaths, car parking spaces and bicycle spaces, public open space,

landscaping, street lighting, walls and fences. The works also include the diversion of an

existing 12inch asbestos watermain which traverses the site at present.

The residential development consists of 210 no. units to be provided as follows:

• 27 no. 1-bed apartments;



The apartments are proposed to be provided within 3 no. apartment buildings (up to 6 no.

storeys in height), plus undercroft basements. The childcare facility has an area of 195 sq.m

and is located at the ground floor level of the southern apartment block within the south

eastern section of the site.

The aim of this report is to provide information on the calculations, estimates and assumptions

used to design the foul sewers, surface water sewers, surface water attenuation and SuDS

systems, watermains and road access for the proposed development.




Figure 1.1 – Site Location, Church Road, Killiney, Dublin 18 (Extract Google Maps)




2. FOUL SEWERS

2.1 Existing services

There is an existing 225mm diameter foul sewer located in Churchview Road approximately

200m to the south-west of the site at the entrance to Auburn Drive, as shown on Irish Water

records (see appendix A). A 225mm diameter foul sewer was extended from this sewer to

service the 8-house Fairhaven development. This sewer is located within Churchview Road

footpath adjacent to the site. Information regarding this recently laid sewer is not shown on

current Irish Water records, but has been identified by a topographical survey of the area and

Irish Water have been notified of its presence. A survey of this sewer will be undertaken at the

earliest opportunity.

There is no existing public foul sewage infrastructure within the proposed site.

2.2 Proposed services

It is proposed to discharge the proposed foul water drainage from the development to the

existing 225mm diameter foul sewer located in the footpath on Churchview Road.

A pre-application enquiry was made to Irish Water regarding the proposed development and

the response can be found in Appendix B. As noted above the existing 225mm diameter foul

sewer located in the footpath at the entrance to the proposed site is not currently on Irish

Water Records as it has been constructed recently. Irish Water has requested details of this

sewer so that they may update their records. The location of the existing sewer can be seen on

drawing 180153-3001. A cctv survey of the foul drainage sewers was also forwarded onto Irish

Water for their information. The existence of this extended 225mm diameter foul sewer serving

the Fairhaven development removes the concern expressed by Irish Water in its Pre-Connection

Enquiry response that “a suitably sized pumping station may be required to be installed”.

This existing 225mm diameter foul sewer connects to the 225mm sewer shown on Irish Water

records at the entrance to Auburn Drive and ultimately discharges to the Shanganagh

Wastewater Treatment Plant.

The applicant is aware that ABP have concerns over the capacity of the receiving foul sewers in

this area. We have met with Dun Laoghaire Rathdown County Council and received

confirmation that they have no issues with the foul drainage from the proposed development

entering the system. Also, as can be seen on the Pre-Connection Enquiry response, Irish Water




have raised no queries with the capacity of the existing network to accommodate the foul

drainage from the proposed development.

Extract from Irish Water response:

“Irish Water have reviewed your pre-connection enquiry in relation to water and

wastewater connections at Church Road, Killiney, Dublin. Based upon the details that

you have provided with your pre-connection enquiry, and the capacity currently

available in the network(s), as assessed by Irish Water, we wish to advise you that,

subject to a valid connection agreement being put in place, your proposed connection

to the Irish Water Network(s) can be facilitated.”

The foul drainage layouts have been submitted to Irish Water in order to obtain a Certificate of

Design Acceptance. Refer to Appendix B for the Certificate of Design Acceptance from Irish

Water. (TBC)

Foul sewage in apartment blocks will be drained on separate internal systems via 150mm

diameter pipes slung from the underside of basement roof slabs and adjacent to the basement

walls. Service pipes from individual apartments will drop through ground floor slabs and

connect into the slung drainage system which in turn will connect by gravity to the external

drainage system. For proposed foul drainage details see drawing 180153-3001.

Any surface water from the basement car parks generated by incidental run-off/spillage will

drain through an underground system of collector pipes, gullies and ACO drains which will drain

through a petrol interceptor prior to discharging into the proposed gravity foul drainage system

for the site at ground floor level in accordance with the requirements of the Greater Dublin

Strategic Drainage Study (GDSDS).

The proposed foul sewers have been designed and will be constructed in accordance with the

Irish Water’s ‘Standard Details for wastewater infrastructure’ and ‘Code of practice for

wastewater infrastructure’. In addition, foul sewers have been designed to Building Regulations

and specifically in accordance with the principles and methods set out in EN 752:2008 and DOE

‘Recommendations for Site Development Works’. In addition, HR Wallingford ‘Tables for the

hydraulic design of pipes, sewers and channels’ and Water UK/WRc ‘Sewers for Adoption – 6th

Edition’ have been applied. Values for roughness of uPVC pipes were obtained from Wallingford

“Tables for the Hydraulic Design of Pipes, Sewers and Channels” and Wavinsewer systems

catalogue.

Foul sewers were sized using the EN752:2008 method in MICRODRAINAGE where:




Q = DUkDU

The following design criteria have been applied in the design of foul sewers:

(i) Discharge units (DU) 3.0 per housing unit (6 litre cistern)

(ii) Unit Consumption Allowance 10% (ii) EN 752 Frequency

Factor (kDU) 0.5 (iv) Pipe Ks 1.5 mm (concrete)

0.6mm (uPVC for flow>0.5D)

0.15mm (uPVC for flow<0.5D)

(v) Minimum velocity 0.75 m/s (self-cleansing vel. Partial flow) 0.6m/s (full flow)

(vi) Maximum velocity 3 m/s (vii) Minimum gradients:

No. of Houses Minimum Pipe Gradient

1-9 150mm dia. @ 1:60 or self-cleansing gradient

10-20 150mm dia. @ self-cleansing gradient

>20 Min 225mm dia.; 1:DN or self-cleansing gradient

Using Irish Water parameters, the peak flow from the site is calculated as 6.5 l/s, however

using the EN752 method in MICRODRAINAGE the peak flow is 12.5 l/s, the latter value has

been used in the sizing of foul sewers and drains within the site.

Sewers and drains shall be laid to comply with the requirements of the Building Regulations

2010 in accordance with the recommendations contained in the Technical Guidance Documents,

Section H (revised 2005). Standard drainage details will be in accordance with the Greater

Dublin Regional Code of Practice for Drainage Works and Irish Water Standard Details for

Wastewater infrastructure.

Please refer to Appendix C for foul sewer calculations.

Please refer to Drawing No. 180153-3001 for foul water layout plan and drawing 180153-3020

for foul water longitudinal sections.




3. SURFACE WATER


There is an existing 225mm diameter concrete surface water sewer in Church Road to the east

of the site which discharges in a north-west direction. Additionally, there is another existing

225mm diameter concrete surface water sewer in Church Road which discharges in a

southernly direction and continues along Churchview Road.

There is no existing public surface water sewage infrastructure within the proposed site.


It is proposed to discharge the proposed surface water drainage from the development to the

existing 225mm diameter concrete surface water sewer located on Churchview Road

approximately 70m from the proposed site entrance.

The applicant is aware that ABP have concerns over the capacity of the receiving surface water

sewers in this area. We have met with Dun Laoghaire Rathdown County Council and received

confirmation that they have no issues with the proposed surface water drainage from the

proposed development entering their system.

Surface water management for the proposed development is designed to comply with the

‘Greater Dublin Strategic Drainage Study (GDSDS) Regional Drainage Policies Technical

Document – Volume 2, New Developments, 2005’ and the ‘Greater Dublin Regional Code of

Practice for Drainage Works, V6.0 2005’. CIRIA Design Manuals C753, C697 and C609 have also

been used to design the surface water drainage system within the site.

The GDSDS guidelines require the following 4 main criteria to be provided by the development’s

surface water design;

• Criterion 1: River Water Quality Protection – satisfied by providing interception storage

and treatment of run-off within the SuDS features e.g. green roofs, permeable paving,

swales and on-line cellular storage attenuation systems.

• Criterion 2: River Regime Protection – satisfied by attenuating run-off with flow control

device prior to discharge to the outfall.

• Criterion 3: Level of Service (flooding) for the site – satisfied by the site being outside

the 1000 year coastal and fluvial flood levels. Pluvial flood risk addressed by




development designed to accommodate a 100 year storm (plus climate change) as per

GDSDS. Planned flood routing for storms greater than 100 year level considered in

design and development run-off contained within site.

• Criterion 4: River flood protection – attenuation provided within the SuDS features e.g.

permeable paving construction, swales and on-line cellular storage attenuation

systems.

3.2.1 SuDS

It is proposed to use a sustainable urban drainage system (SuDS) approach to stormwater

management throughout the site. The overall strategy aims to provide an effective system to

mitigate the adverse effects of urban stormwater runoff on the environment by reducing run-off

rates, volumes and frequency, reducing pollutant concentrations in stormwater, contributing to

amenity, aesthetics and biodiversity enhancement and allow for the maximum collection of

rainwater for re-use where possible. In addition, SuDS features aim to replicate the natural

characteristics of rainfall run-off for any site by providing control of run-off at source and this

has been achieved by the current proposals.

Infiltration testing has been undertaken on the site and it has returned very poor infiltration

rates. Therefore none of the SuDS measures proposed for the scheme have been designed to

allow for infiltration to ground.

SuDS are a requirement of Dun Laoghaire Rathdown County Council under their ‘Regional Code

of Practice for Drainage Works’ and ‘The Greater Dublin Strategic Drainage Study’. Additionally,

these systems are recommended under the 2009 guidelines, ‘The Planning System and Flood

Risk Management’.

There are a number of SuDS features proposed which have been designed in accordance with

CIRIA documents C753, C697 and C609 as follows:

• Swales (wet): Broad, shallow drainage channels covered in grass which can treat, convey

and attenuate runoff, at source. It has been established that the existing subgrade does

not support infiltration to ground. Swales also can promote biodiversity. These are located

adjacent to the site access road.

• Permeable Pavement: Porous surfacing (paving block or open graded material) which can

treat rainwater, at source, and allow infiltration through to an underlying porous sub-base

where water can be stored within the voids of the sub-base before being slowly released to

the drainage collection system through natural flow via the porous medium.




Closed permeable paving systems are proposed to be used as the existing subgrade

(ground) is not capable of absorbing the water through infiltration. This type of permeable

paving system includes an impermeable geotextile at its base and includes an outlet to the

surface water system. These systems will allow some form of storage for small rainfall

events and will result in water evaporation and adsorption in small quantities, therefore

there will be less run-off from these areas in small rainfall events thus mimicking the

natural response for this catchment.

As well as reducing the amount of run-off from the surface, permeable paving will slow

down the rate of runoff from the pavement in extreme rainfall events contributing to

attenuation of flows. In addition, permeable paving will increase the quality of water which

is intercepted by the system through filtration, biodegradation, pollutant adsorption and

settlement and retention of solids, also the reduction in peak flows to the outfall will

enhance settlement and biodegradation of pollutants.

It is proposed to use these systems in private car-parking bays and surface water storage

within these systems will be further mobilised by providing a 100mm diameter pipe at the

outlet to the site drainage system.

• Green roofs: Green roofs provide ecological, aesthetic and amenity benefits and intercept

and retain rainfall at source, reducing the volume of runoff and attenuating peak flows.

Green roofs absorb most of the rainfall that they receive during ordinary events although

they will only contribute to attenuation of flows for larger events. Additionally, green roofs

treat surface water through removal of atmospherically deposited urban pollutants. Finally,

green roofs may reduce heating (by adding mass and thermal resistance value) and

cooling (by evaporative cooling) loads on a building. Green roofs will comply with Dun

Laoghaire Rathdown County Council Green Roofs Guidance document.

Extensive Green Roofs: A planted roof area with low growing, low maintenance plants

consisting of self-sustaining mosses, sedums, succulents, herbs or grasses over a drainage

layer and waterproofing membrane. Extensive green roofs provide ecological, aesthetic

and amenity benefits and intercept, treat and retain rainfall, reducing the volume of runoff

and attenuation peak flows. Extensive roofs are usually only accessed for maintenance.

Intensive Green Roofs: Planted, accessible roof areas with high amenity benefits which

include planters or trees over a drainage layer and waterproofing membrane which provide

similar benefits to extensive green roofs. Intensive roofs are usually accessible.

Green roofs will be provided on a minimum of 60% of apartment roof space. For

maintenance purposes, green roofs will be accessed from stairwells within the apartment

buildings.

http://en.wikipedia.org/wiki/HVAC

http://en.wikipedia.org/wiki/Mass

http://en.wikipedia.org/wiki/Evaporative_cooling




• Cellular Attenuation System: Proprietary modular block or arch structure with a

maintenance/inspection tunnel for providing underground surface water attenuation

storage. These will be closed systems as site investigations have indicated poor infiltration

rates within the site. These will be the primary attenuation systems for the site and will be

located adjacent to the south of the apartment blocks (see drawing 180153-3000).

Concrete slabs will be placed over these tanks to combat the risk of flotation.

• Petrol Interceptor: A proprietary oil/water separator which prevents hazardous chemical

and petroleum products from entering watercourses and public sewers. This is proposed at

the outfall from the site.

Please refer to Appendix H for SuDS calculations and summary.

Please refer to Drawing No. 180153-3000 for surface water layout plan.

Please refer to Drawing Nos. 180153-3015 to 3016 for standard SuDS details.

3.2.2 Long Term Storage

In addition to limiting the run-off rate through attenuation (see below), the GDSDS requires

that run-off volume from the site is limited in extreme events. The objective is to match the

run-off volume discharged to the downstream receiving watercourse/public sewer after

development to that which occurred prior to development. This volume is calculated by

comparing the 100 year 6 hour event for ‘pre’ and ‘post’ development and is referred to as

“Long-Term Storage”.

Where long-term storage is provided, this has a direct effect on the permissible site discharge

rate from the site, as explained further forward.

Due to the large extent of development within the site it is not proposed to provide long-term

storage, this effects the permissible site discharge and resulting attenuation volumes required

and will be explained in the following section.

3.2.3 Greenfield Run-off – Pre-Development

For informational purposes only, the existing pre-development greenfield runoff rate for the

development has been calculated and is compared to the rate discharged from the site post-

development.

According to the GDSDS section 6.6.1.2, the method used for determining peak flow rates for

small greenfield catchments is the UK ‘Institute of Hydrology Report 124, Flood Estimation for




small Catchments’. Where long-term storage can be provided, or is not necessary, surface

water can be discharged at a higher value than QBARrural, this discharge rate (QBARgrowth) is

dependent on the design return period and the corresponding growth factor from the GDSDS

Table 6.6. However, if long-term storage cannot be provided on-site the discharge rate from the

site should be kept to QBARrural. or 2 l/s/ha. This is the case for this development.

The IH 124 method calculates QBARrural which is the mean annual flood flow from a rural

catchment. As the subject site area is less than 50 hectares, the calculated QBAR is to be

linearly interpolated from the calculated value to produce a reduced available outflow based on

the actual site area, as per GDSDS section 6.6.1.

QBARrural = 0.00108 x (Area)0.89(SAAR)1.17(SOIL)2.17

where:-

QBARrural = Mean Annual Flood (m3/s)

Area = Catchment Area (km2)

SAAR = Standard Average Annual Rainfall (mm)

SOIL = SOIL index from Flood Studies Report

GDSDS Table 6.6 defines the growth curve for the Dublin region that should be used to factor

the mean annual greenfield peak flow to obtain flows for other return periods.

Return Period Growth Curve Factor

1 0.85

QBARrural 1.0

30 2.1

100 2.6

Table 3.1 – Growth Curves for QBAR for Dublin from GDSDS

Using data received from Met Eireann for Irish Grid co-ordinates E 324000, N 225000 (centre of

site co-ordinates are: E 324437, N 225534), the SAAR is determined as 813 mm.

The existing greenfield site consists of a SOIL type 4 as defined using the Flood Studies Report

- Winter Rainfall Acceptance Maps (WRAP). A more accurate approach is to use the ‘The

Classification of Soils from Winter Rainfall Acceptance Rate, Flood Studies Report Table 4.5’ if

more information is available relating to the site. This approach is used for this development as

ground investigations have been undertaken on the site and this information has been used in

the calculations. These investigations indicate a very low infiltration rate for the site and that

‘rainfall is not anticipated to infiltrate to the underlying groundwater body with ease’.




Appendix D shows how the SOIL Value for the site was determined as being Type 4.

Permissible site discharge for the site has been determined as follows:-

Total Site Area (red-line boundary) = 1.48 Ha

SAAR = 813mm

SOIL = Type 4

Therefore the permissible site discharge for the development (QBARrural ) is 7.7 l/s.

Permissible site discharge calculations are included in Appendix D of this report.

3.2.4 Surface Water Runoff Coefficients

As a large proportion of runoff is routed through SuDS features these will have an attenuating

effect which reduce the rate of stormwater runoff for every rainfall event. Also, SuDS features

would reduce the runoff volume through evaporation, transpiration, infiltration and depression

storage of the water within each system.

Runoff coefficients have been agreed with DLRCC and have been applied as follows:

Roofs - Type 1 (Draining to traditional gullies) = 1.0

Roofs – Type 2 (Draining to SuDS features) = 0.75

Green Roofs = 0.85 (150mm deep extensive, greater depth for intensive)

Roads and Footpaths - Type 1 (Draining to gullies) = 0.95

Roads and Footpaths - Type 2 (Draining to SuDS features) = 0.70

Paved Areas = 0.95

Permeable Paving = 0.50

Bioretention Areas = 0.70

Grassed Areas = 0.47 (soil type 4 - Flood Studies Report)

Public Open Space = 0.47 (soil type 4 - Flood Studies Report)

3.2.5 Surface Water Attenuation - Site Investigation

A Site Investigation of the lands was carried out by Ground Investigations Ireland (GII) Ltd in

January 2019, the results of which were described in an interpretive report. A Phase 1

Hydrogeological Site Assessment was also undertaken in May 2019.

Refer to appendix K & L for a copy of these reports.




In summary, the existing ground consists of topsoil to an average depth of 0.4m below ground

level across the site. The subsoil can be described as soft to firm brown sandy gravelly CLAY to

an approximate depth of 1.0m below ground level. Below this level the cohesive deposits can

be described as stiff with cobble and boulder content. The maximum depth of cohesive deposits

encountered was 2.45m. The depth of bedrock encountered varied from 0.6m to 2.45m below

ground level.

Soil infiltration rates were assessed as part of the site investigation, the assessment was

undertaken by excavating trial pits based on the requirements of BRE Digest 365 and CIRIA

SuDS Manual C753. The FSR (Winter Rain Acceptance) SOIL value determined was used to

calculate the pre-development characteristics of the in-situ soil and the corresponding

greenfield run-off of the site, mentioned previously.

The infiltration tests were carried out at 3 locations to determine the infiltration rate applicable

to SuDS features for the calculation of interception storage (see 3.2.7 further forward).

Infiltration rates of 4.527x10-6 m/s and 1.221x10-5 m/s were calculated for two of the

soakaway locations with the water level in the third dropping too slowly to allow calculation of

‘f’ the soil infiltration rate. These tests illustrate the locations are not suitable for soakaway

design and construction.

The hydrogeological report noted that the groundwater flow follows the topography of the site

and generally flows in a southwesterly direction. However, regionally groundwater is expected

to flow in an east to southeasterly direction towards the sea. The monitoring wells suggest that

the upgradient or eastern sides of the proposed basements and attenuation structures will be

partially constructed below the water table. However, the depth of penetration is not

anticipated to be significant. The report suggests a drainage layer/blanket be positioned around

the attenuation structures to facilitate the movement of groundwater.

3.2.6 Surface Water Attenuation - Design

The GDSDS requires flood waters for a 100 year return period to be managed on-site, therefore

this return period is adopted for attenuation calculations. In addition a further 10% increase

has been added for climate change.

The site will be divided into two catchments, northern and southern. The catchments will work

in series. They will have a separate attenuation storage systems but one discharge outfall

location to the public surface water network. The final surface water run-off will outfall to an




existing surface water manhole located on Churchview Road. Surface water attenuation for the

site will be provided within underground ‘Stormtech’ proprietary modular arch systems.

Furthermore, the attenuation system will be surrounded in an impermeable geomembrane

(plastic liner or a bentonite liner) to ensure that the surrounding water in the soil (if present)

does not infiltrate to the system. As this proposed attenuation system is designed with no

allowance for infiltration for surface water management purposes, there will be no impact on

the capacity of the proposed systems. A concrete slab will also be placed over the tank to

mitigation against flotation.

The configuration of the development drainage infrastructure system, including Sustainable

Drainage System features (SuDS) with underground attenuation, is designed such that there is

one overall catchment draining to the outfall. Within this overall catchment, there are two sub-

catchments draining to attenuation systems, each with a hydrobrake to restrict the flow

discharging to the downstream drainage network and mobilise (activate) storage within each

system. These sub-catchments work together in series where the controlled flow from one

system connects to the next system. In this case the downstream attenuation system receives

flow from the upstream hydrobrake as well as flow from the surface water runoff generated in

its own sub-catchment drainage system.

This surface water system has been hydraulically modelled in MICRODRAINAGE to ensure that

the overall discharge at the end of the hydraulic system (i.e. the outlet to the public sewer) is

at, or below, the greenfield rate that discharges from the site at present. A MICRODRAINAGE

Simulation model has been created for the entire site accordingly.

MICRODRAINAGE Simulation uses the Wallingford Procedure, time/area full hydrograph

methodology, including energy and momentum equations for dynamic analysis of surface water

networks. The site drainage network is modelled as one system where all flows, capacities,

water levels, surcharged manholes etc are determined throughout the network for each critical

storm duration.

Therefore, the final combined discharge rate to the sewer from the outlet will be

kept at (or below) the total permissible discharge rate defined above.

Maximum rainfall data from Extreme Rainfall Return Period values produced by Met Eireann

was used to input into MICRODRAINAGE to determine maximum flood volumes. Rainfall data

for the site was sourced from an Annual Average Rainfall (AAR) Grid (1981-2010) and a Depth

Duration Frequency model produced by Met Éireann (Available from:




http://www.met.ie/climate/products03.asp). This data was input into MICRODRAINAGE to

determine the maximum flood volume for the 1 in 100 year rainfall event.

AAR = 813 mm

Ratio M560/M52d = 15.7

M560 = 0.28 mm

As required under the GDSDS the above data was increased by a factor of 10% for the

hydraulic analysis.

The volume of attenuation provided within the site is as follows:-

Northern Attenuation system = 232 m3

Southern Attenuation system = 132 m3

It should be noted that attenuation volumes required are based on the results of the

MICRODRAINAGE hydraulic simulation summary of Critical Results by Maximum Level.

Hydrobrake maximum head and discharges are based on results of MICRODRAINAGE hydraulic

simulation summary of Critical Results by Maximum Outflow.

It should also be noted that within the site overland flowpaths will be provided to direct run-off

from high intensity, short duration storms which might fail to enter the drainage system. Drop

kerbs will be provided at road edges at low spots in order to allow overland flow to enter open

space areas or discharge to watercourses. Additionally, a minimum freeboard of 500mm has

been provided above the 1 in 100 year flood levels to all building floor levels.

Please refer to Drawing No. 180153-3000 for surface water layout plan.

Please refer to Drawing No. 180153-3015 for stormtech attenuation details.

Please refer to Appendix E for attenuation calculations.

3.2.7 Interception Volume

The GDSDS requires that no run-off should directly pass to the receiving watercourse for rainfall

depths of 5mm, therefore interception should be provided at source where practicable. The

volume of interception required is based on 5mm of rainfall depth from 80% of the runoff from

impermeable areas as defined in the GDSDS (Appendix E section E2.1.1).




The interception volume attributable to each SuDS feature (swale, green roof etc.) consists of

the volume of water that can infiltrate to the ground, what will evaporate into the atmosphere

and what can transpirate through plants and vegetation. Additionally, there will some losses of

water due to absorption and wetting of stone and soil media.

Not all SuDS features will be able to achieve infiltration, evaporation, transpiration and losses

due to absorption/wetting, for example green roofs will have no infiltration capacity. The limits

for each SuDS feature type are taken into account when calculating interception volumes.

Additional evapotranspiration volume will be available in each of the SuDS features whereby a

50mm nominal depth storage reservoir will be provided below the invert of the outgoing pipe or

control within each feature. This storage will be additional to the attenuation and interception

storage required and will allow long-term evapotranspiration (over minimum 24 hours) of run-

off to ensure that a minimum of 5mm interception volume is achievable.

The total interception volume required for the site is 30.2 m3, the volume provided for the site

is 13.5 m3. This volume is lower than that required is due to the poor infiltration qualities of the

existing ground and only takes into account infiltration to the existing stratum.

It is anticipated that the actual interception storage achievable for the site will far exceed what

is required as the interception storage attributable to the losses in stone and soil media, such as

the stone media used in filter drains, was not included in the calculations which is considered to

be conservative.

Please refer to Appendix F for Interception Volumes.

Infiltration tests were undertaken throughout the site to determine the infiltration rate

applicable to SuDS features for the calculation of interception storage. These tests showed that

the minimum infiltration rate applicable for SuDS features is 8.37x10-5 mm/hr.

Refer to appendix K for a copy of The Ground Investigation Report.

3.2.8 Treatment Volume

The GDSDS requires that a “treatment volume” (Vt) be provided in order to prevent any

pollutants or sediments discharging into river systems, additionally a ‘treatment train’




stormwater runoff management system is required. According to CIRIA document C697 the

following treatment train approach is necessary:

Roofs – 1 Treatment Stage

Road Areas – 2 Treatment Stages

Paved Areas excluding Roads - 1 Treatment Stage

The treatment volume is based on treatment 15mm of rainfall depth from 80% of the runoff

from impermeable areas as defined in the GDSDS (Appendix E section E2.1.2).

All run-off areas will pass through the required number of treatment stages prior to discharging

to the downstream outfall. Treatment methods include swales, permeable paving, ‘Stormtech’

attenuation system and petrol interceptor.

The total treatment volume required for the site is 30.2 m3, the volume provided for the site is

277.1 m3.

Please refer to Appendix G for treatment Volumes.

3.2.9 Surface Water Sewers

Surface water from the proposed development will be discharged after attenuation to the

existing surface water sewer located in Churchview Road to the south of the site.

Surface water sewers are designed in MICRODRAINAGE using the Modified Rational Method.

The return period for sizing pipes is based on the following:-

• Department of Environment – Recommendations for Site Development Works for

Housing Areas (1998), Table 3.1;

• GDSDS – Regional Drainage Policies – Volume 2 – New Development (2005), Section

6.5;

• IS EN 752:2008 - Drain and Sewer Systems Outside Buildings, Table 2;

• Building Regulations (2005) – Section H - Drainage and Wastewater Disposal, Section

1.5.7.

In addition, the pipe system was checked for the 30 year return period where no flooding from

manholes was encountered. The following parameters applied:




Return period 2 year (flooding check for 30 year event)

Time of entry 4 minutes

Pipe Ks 0.6mm (concrete); 0.15mm (uPVC)

Minimum velocity 0.75 m/s

Maximum velocity 3.0 m/s

Effective runoff coefficients for each pipe catchment have been determined based on the runoff

characteristics for each surface contributing to flows within the catchment.

The minimum pipe diameter for public surface water sewers is 225mm.

Surface water in apartment blocks will be drained on a separate system via 150mm to 225mm

diameter pipes slung from the underside of the basement roof slab, the slung surface water

system will then discharge into the external drainage network and attenuation system.

Rainwater downpipes from roofs will project through the ground floor slab and connect into the

slung drainage system.

Values for roughness of uPVC pipes were obtained from Wallingford “Tables for the Hydraulic

Design of Pipes, Sewers and Channels” and Wavinsewer systems catalogue.

A surcharge analysis was performed for the proposed surface water sewer network for a 1 in

100 year storm event and further analysis to determine the impact of a 50% blockage in the

system. The surcharge analysis and blockage analysis did not return any significant issues with

the proposed system. Where flooding was expected as a result of this analysis suds features

and overland flow paths would direct the water away from the buildings to ensure the

residential development were unaffected. A full commentary on the returned results can be

found in Appendix M.

Finally, it should be noted that a Stormwater Audit on the above proposals will be undertaken

prior to full submission. The Stormwater Audit and designer’s response will be submitted under

separate cover.

Please refer to Drawing No. 180153-3000 for surface water sewer layout plan and Drawing No.

180153-3031 for surface water longitudinal sections.

Please refer to Appendix H for summary of SuDS calculations.

Please refer to Appendix I for surface water sewer calculations.




3.2.10 Amenity

SuDS features should be designed to replicate a natural environment with a visual appeal,

promote both public and wildlife usage and promote biodiversity within urban environments. In

addition, SuDS features should aim to use water as a resource where possible.

Substantial amenities, biodiversity and water usage provision has been included in the proposed

site which includes extensive and intensive green roofs and swales. Please refer to landscape

documentation for further detail.

3.2.11 SuDS Maintenance

The SuDS features proposed above for the site will require the following maintenance:

Permeable Surfacing: Regular brushing and removal of leaves, removal of weeds as necessary.

Stabilise and mow contributing and adjacent landscaped areas regularly. Repair any

depressions, rutting, cracked or broken blocks considered detrimental to the structural

performance or a hazard to users.

Wet Swales: Requires regular inspection of inlets and outlets, vegetation, mulching and the

removal of nuisance plants and rubbish as necessary. Trees and vegetation should be trimmed

every 2 years. Swale surface should be spiked, scarified and removed of ‘thatch’ every 3 years

with regular inspection of surface infiltration to avoid areas of ponding. Repair erosion at inlets

and outlets and re-turf surfacing as required. Wet swales will be maintained from adjacent

access roads.

Hydrobrake Manhole: Normally little maintenance is required as there are no moving parts

within a hydrobrake, however, after installation, hydrobrakes should be inspected to ensure the

hydrobrake orifice is not blocked on a monthly basis for three months and thereafter at six

monthly intervals and hosed down if required. Remove rubbish or debris from hydrobrake if

present. Hydro-Brake Flow Controls are fitted with a pivoting by-pass door, which allows the

manhole chamber to be drained down should blockages occur.

Petrol Interceptor: Systems should be visually inspected for every rainfall event for 30 days

after installation and the amount of sediment measured to give the operator an idea of the

expected rate of deposition. Systems should then be inspected every 6 months to verify the

appropriate level of maintenance. Floating debris and solids should be removed and the sump




cleaned with a conventional sump vacuum cleaner. Filter media should be replaced and

sediments, oils and grease should be removed where required.

4 WATERMAINS


There are existing 9inch and 150mm diameter public watermains located on Church Road

adjacent to the site. There are also existing 800mm diameter and 9inch watermains located in

Chuchview Road to the south of the site.

In addition, there is an existing 12inch watermain traversing the site from east to west (see

appendix A for existing watermain locations).


A pre-application enquiry was made to Irish Water regarding the proposed development and the

response can be found in appendix B.

The proposed watermain layouts have also been submitted to Irish Water in order to obtain a

Certificate of Design Acceptance. Refer to Appendix B for the Certificate of Design Acceptance

from Irish Water. (TBC)

In addition, Irish Water’s dedicated diversion section were contacted to co-ordinate the diversion

of the existing 12inch watermain traversing the site as it is proposed to divert this main within

the site and replace the diverted section with a 300mm diameter pipe. The diversion will be

carried out between existing joints of the 12inch main as shown on drawing 180153-3002. A 10m

wide wayleave will be placed over the diverted public watermain in accordance with Irish Water

requirements.

An application has also been lodged with Irish Water to obtain a Permanent Works Services

Agreement for the watermain.

A new connection will be made to the diverted 300mm diameter watermain at the southern end

of the site. A survey has been undertaken to verify the location of the existing watermain as

requested by Irish Water.




A proposed 150mm diameter watermain and new fire hydrants will be provided throughout the

site to service the new development.

The estimated peak demand from the development will be 6.15 l/s with the average daily

demand being 85.05 m3.

A bulk water meter will be provided at the connection to the site. The supply arrangements will

be carried out to the requirements of Irish Water.

Please refer to Appendix J for watermain calculations.

5 ROADS

Refer to Traffic and Transport Assessment Report included as part of the planning application

pack.

6 FLOOD RISK ASSESSMENT

6.1 Approach

This section of the report considers ‘The Planning System & Flood Risk Management –

Guidelines for Planning Authorities’ as they relate to the proposed application.

6.2 Planning System & Flood Risk Management Guidelines

6.2.1 General

“The Planning System and Flood Risk Management Guidelines for Planning Authorities”,

November 2009 and its technical appendices outline the requirements for a site-specific flood

risk assessment.

This type of development is classified as “highly vulnerable development” according to Table

3.1 of the Guidelines. Table 3.2 of the Guidelines indicates that this type of development is

appropriate and compatible with flood zone C i.e. outside the 1000 year flood extents.




6.2.2 Flood Risk Assessment Stages

This site specific flood risk assessment will use existing flood risk information to determine the

flood zone category of the site i.e. to check if the Guidelines Sequential Approach has been

applied, see Figure 2 below for details.

Figure 2 – Sequential Approach mechanism in the Planning Process

Flood risk is normally assessed by a flood risk identification stage followed by an initial flood risk

assessment. The Greater Dublin Strategic Drainage Study (GDSDS) states that if the risk of

flooding is found to be low, there are no restrictions to development. However, if the risk is

found to be medium or above, a more detailed flood impact assessment stage must be

approved which includes an assessment of surface water management, flood risk and

mitigation measures to be applied.

6.3 Flood Risk Identification Stage

6.3.1 General

The flood risk identification stage uses existing information to identify and confirm whether

there may be flooding or surface water management issues for the lands in question that may

warrant further investigation.




6.3.2 Information Sources Consulted

Information sources consulted for the identification exercise and an assessment are outlined in

Table 1 below.

Information Source Comments Assessment

Predictive and historic flood

maps, and benefiting lands

maps, such as those

available on

http://www.floodmaps.ie;

OPW www.floodmaps.ie

website consulted.

There were no OPW land

commission schemes or

benefitting land zones

within the subject site’s

boundary.

Predictive fluvial, coastal,

pluvial and groundwater

flood maps.

ECFRAMS The proposed site is

located 1.75Km from the

Irish Sea and

approximately 1km from

the Kill-O-Grange

Stream. There is no

ECFRAMS mapping for

this area available.

Topographical maps, in

particular digital elevation

models produced by aerial

survey or ground survey

techniques;

OSI Maps consulted, site

topographic survey undertaken

and analysed.

No evidence of flood risk

due to topography.

Information on existing

public sewerage condition

and performance;

GDSDS performance maps for

existing sewerage in the vicinity

of the subject site examined.

GDSDS flood mapping

does not extend to this

area.

Alluvial deposit maps of the

Geological Survey of

Ireland. These maps, while

not providing full coverage,

can indicate areas that

have flooded in the past.

GSI maps consulted. No karst features are in

this area. The site

consists primarily of

made ground in the

topsoil and the subsoil.

Groundwater

vulnerability is Moderate.

The site is located on a

poor aquifer, generally

unproductive except for

local zones. The site

consists of poorly

productive bedrock.

Bedrock comprises of

granite.

Phase 1 Hydrogeological

Site Assessment

Report and recommendations

reviewed.

Report notes that the

proposed basements will

be partially constructed

below the water table.

However, the depth of

http://www.floodmaps.ie/




Information Source Comments Assessment

penetration is not

anticipated to

be significant.

Table 1 - Information sources consulted

6.3.3 Source-Pathway-Receptor Model

A Source-Pathway-Receptor model was produced to summarise the possible sources of

floodwater, the people and assets (receptors) that could be affected by potential flooding (with

specific reference to the proposals) and the pathways by which flood water for a 0.1%AEP

(Annual Exceedance Probability) and 1%AEP storms could reach the receptors, see Table 2. It

provides the probability and magnitude of the sources, the performance and response of

pathways and the consequences to the receptors in the context of the post primary

development proposal.

Source Pathway Receptor Likelihood Impact Risk

Tidal Tidal flooding from

coast 1.75km

away.

Residents (people)

development, visitors,

buildings and other

property such as

vehicles located in car

park areas and

basement.

Remote High Low

Fluvial Flooding from

nearest

watercourse (Kill-

O-Grange Stream)

approximately 1km

away.

Residents (people)


buildings and other

property such as


park areas and

basement.

Remote High Low

Surface Water

Drainage

(Pluvial)

Flooding from the

surcharging of the

development’s

drainage systems.

Residents (people)


buildings and other

property such as


park areas and

basement.

Possible High Moderate

Surface Water

- Pluvial

Flooding from

internal sources –

overland flows.

Residents (people)


buildings and other

property such as


park areas and

basement.


Surface Water Flooding from Residents (people) Possible High Moderate




Source Pathway Receptor Likelihood Impact Risk

– External external sources. development, visitors,

buildings and other

property such as


park areas and

basement.

Groundwater

flooding

Rising GWL on the

site.

Residents (people)


buildings and other

property such as


park areas and

basement.


Human or

Mechanical

Error (Pluvial)

Restricted Pipe,

Petrol Interceptor

and hydrobrake.

Residents (people)


buildings and other

property such as


park areas and

basement.


Table 2 – Source-Pathway-Receptor Analysis

6.3.4 Source-Pathway-Receptor Model Results

It is clear from the above flooding analysis that the proposed site is not at risk from tidal or

fluvial flooding due to its geographic location and topography. Due to proposed levels, if

flooding of proposed roads occur, any water will be kept within the road reservation or directed

to an area of open space. It will avoid all buildings.

However, there is a moderate risk of pluvial flooding of the drainage infrastructure, a moderate

risk of flooding of the site due to the potential surcharging and blockage of the new drainage

network and a moderate risk due to groundwater flooding caused by the below ground

construction. These risks can be mitigated as noted in the section below.

Therefore the type of development proposed is appropriate for this flood zone category which is

Zone C. The Guidelines Sequential Approach is therefore met and the ‘Avoid’ principal achieved

and an initial flood risk assessment is not required.

6.3.5 Mitigation Measures

Proposed mitigation measures to address residual flood risks are summarized below;




M1. To ensure that the proposed buildings have sufficient flood protection against future

extreme pluvial flood events then the proposed finished floor levels and external site

levels have been designed to be 500mm above the maximum flood level for the 1:100

year return period for the site attenuation.

M2. A ramp and channel gully system will serve to prevent any surface water from entering

the undercroft of the building. Refer to drawing 180153-3000.

M3. The drainage network is designed in accordance with the recommendations of the

GDSDS and provides attenuated outlets and associated storage up to the 100 year

event.

M4. Overland flow routes for pluvial events should not be built on or become blocked off.

Overland flow routes should be designed to direct to open space areas away from

dwellings. Refer to drawing 180153-3000.

M5. The location of all dropped kerbs and side inlet gullies will ensure all overland flow

paths are not impeded.

M6. Sustainable Urban Infrastructure: the proposed development will include SUDS features

e.g. permeable paving, filter drains, green roofs etc.

M7. All mechanical plant used in the surface water network will be maintained and cleaned

regularly. A surcharge analysis of the system was undertaken to determine the impact

of a 50% blockage in the network and returned no significant issues.

M8. A gravel drainage layer/blanket should be installed surrounding the upgradient sides of

the basement and the attenuation tank to facilitate the movement of groundwater

across the site and reduce the risk of groundwater flooding.

6.3.6 Residual Risks

Remaining residual flood risks, following the detailed assessment and mitigation measures

include the following;

1. Pluvial flooding from the drainage system related to a pipe/culvert blockage or from

flood exceedance.

2. Pluvial flooding from the development’s drainage system for storms in excess of the

100 year design capacity.




6.4 Conclusion

The proposed flood mitigation measures outlined above should be implemented, including the

use of drainage layer/blanket around the basements and attenuation tanks as highlighted in the

Phase 1 Hydrogeological Site Assessment. It is considered that the flood risk mitigation

measures, once fully implemented, are sufficient to provide a suitable level of protection to the

proposed development and will not cause an increased risk of flooding to external properties.

A regularly maintained drainage system will ensure that the network remains effective and in

good working order should a large pluvial storm occur. In the event of extreme pluvial flooding

then overland flood routes will direct water towards the open space areas. A surcharge analysis

was performed for the proposed surface water sewer network for a 1 in 100 year storm event

+ 10% climate change to determine the impact of a 50% blockage in the system. The

surcharge analysis and blockage analysis did not return any significant issues with the proposed

system. Should extreme pluvial flooding occur in excess of the development’s drainage capacity

i.e. exceeding 1%AEP or assuming significant blockage of the system, then overland flood

routes towards the on-site open spaces will protect the development. The results of this

analysis can be found in Appendix M.

While the development constitutes ‘highly vulnerable’ development, it is appropriate for this

flood zone and the scheme is designed to ensure that the risk of flooding of the development is

reduced as far as is reasonably practicable. The development does not increase the risk of

flooding to adjacent areas and roads once mitigation measures are implemented.

DBFL CONSULTING ENGINEERS MAY 2019




APPENDIX A

Existing Drainage Records

Roche s town Ave nue Are a Dra ina g e

Le g e ndStormwater Gravity Mains (Irish Water Owned)

Surfa ceStormwater Gravity Mains (Non-Irish Water Owned)

Surfa ceStorm Manholes

Ca s ca d eCa tchpitHa tchboxLa m pholeSta nd a rdO the r; Unknown

Storm InletsGullySta nd a rdO the r; Unknown

Storm FittingsVe nt/ColO the r; Unknown

Storm Discharge PointsO utfa llO ve rflowSoa kawayO the r; UnknownStorm Culve rtsStorm Cle a n O uts

Sewer Gravity Mains (Irish Water owned)Com bine dFoulO ve rflowUnknown

Sewer Gravity Mains (Non-Irish Water owned)Com bine dFoulO ve rflowUnknown

Sewer Pressurized Mains (Irish Water owned)Com bine dFoulO ve rflowUnknown

Sewer Pressurized Mains (Non-Irish Water owned)Com bine dFoulO ve rflowUnknown

Nove m be r 20, 2017

0 0.1 0.20.05 m i

0 0.15 0.30.075 km

1:5,000

© O rd na nce Survey Ire la nd | © O rd na nce Surve y Ire la nd |

Iris h Wa te r g ive s this inform a tion a s to the pos ition of itsund e rg round ne twork a s a g e ne ra l g uid e only on the s trictund e rs ta nd ing tha t it is ba s e d on the be s t a va ilableinform a tion provid e d by e ach Loca l Authority in Ire la nd . Its hould not be re lie d upon in the e ve nt of exca va tions or othe rworks be ing ca rrie d out in the vicinity of the ne twork. Theonus is on the pa rtie s ca rrying out the works to e ns ure thee xact loca tion of the ne twork is id e ntifie d prior to m echa nica lworks be ing ca rrie d out. Se rvice pipe s a re not g e ne ra llys hown but the ir pre s e nce s hould be a nticipa te d .

Re prod uce d from the O rd na nceSurvey O f Ire la nd by Pe rm is s ion of theGove rnm e nt. Lice ns e No. 3-3-34

“Ga s Ne tworks Ire la nd (GNI), the ir a ffilia te s a nd a s s ig ns , a cce pt nore s pons ibility for a ny inform a tion conta ine d in this d ocum e nt conce rningloca tion a nd te chnica l d e s ig na tion of the g a s d is tribution a nd tra ns m is s ionne twork (“the Inform a tion”). Any re pre s e nta tions a nd wa rra ntie s expre s s orim plie d , a re exclud e d to the fulle s t exte nt pe rm itte d by law. No lia bility s ha ll beacce pte d for a ny los s or d a m a g e includ ing , without lim ita tion, d irect, ind irect,s pecia l, incid e nta l, punitive or cons e que ntia l los s includ ing los s of profits ,a ris ing out of or in connection with the us e of the Inform a tion (includ ing m a ps orm a pping d a ta ). NO TE: DIAL BEFO RE Y O U DIG Phone 1850 427 747 or e-m a ild ig @g a s ne tworks .ie – The a ctua l pos ition of the g a s /e lectricity d is tribution a ndtra ns m is s ion ne twork m us t be ve rifie d on s ite be fore a ny m echa nica lexcava ting ta ke s pla ce. If a ny m echa nica l exca va tion is propos e d , ha rd copym a ps m us t be re que s te d from GNI re g a s . All work in the vicinity of the g a sd is tribution a nd tra ns m is s ion ne twork m us t be com ple te d in a ccord a nce withthe curre nt e d ition of the He a lth & Sa fe ty Authority publica tion, ‘Cod e ofPractice For Avoid ing Da ng e r From Und e rg round Se rvice s ’ which is a va ila blefrom the He a lth a nd Sa fe ty Authority (1890 28 93 89) or ca n be d ownloa d e dfre e of cha rg e a t www.hs a.ie.”

´

S u b j e c t t o C o n t r a c t / C o n t r a c t D e n i e d – F o r I d e n t i f i c a t i o n P u r p o s e s o n l y

Roche s town Ave nue Are a Wate r

Le g e ndFlow Control Valves

Non-returnHyd roO rifice Pla tePRVPSVO the r

Boundary ValvesO pe nClos e dPa rt Clos e d

Boundary MeterDis trict (Bound a ry Me te r)Tre a tm e nt Pla nt

ReservoirPota bleRaw Wate rPum p Sta tions

Water Mains(Irish Water Owned)Untre a te dPota ble Wate r

Water Mains(Non Irish Water Owned)Untre a te d

Pota ble Wate rWater Lateral Lines

Iris h Wate rNon IWWate r Aba nd one d Line s

Nove m be r 20, 2017

0 0.1 0.20.05 m i

0 0.15 0.30.075 km

1:5,000

© O rd na nce Survey Ire la nd | © O rd na nce Surve y Ire la nd |

Iris h Wate r g ive s this inform ation a s to the pos ition of itsund e rg round network a s a g e ne ra l g uid e only on the strictund e rs ta nd ing that it is ba s e d on the be s t a va ilableinform a tion provid e d by e ach Loca l Authority in Ire la nd . Its hould not be re lie d upon in the e ve nt of exca vations or othe rworks be ing ca rrie d out in the vicinity of the network. Theonus is on the pa rtie s ca rrying out the works to e ns ure theexact loca tion of the network is id e ntifie d prior to m echa nica lworks be ing ca rrie d out. Se rvice pipe s a re not g e ne ra llys hown but the ir pre s e nce s hould be a nticipate d .

Re prod uce d from the O rd na nceSurvey O f Ire la nd by Pe rm is s ion of theGove rnm e nt. Lice ns e No. 3-3-34

“Ga s Networks Ire la nd (GNI), the ir a ffiliate s a nd a s s ig ns , a cce pt nore s pons ibility for a ny inform a tion conta ine d in this d ocum e nt conce rninglocation a nd te chnica l d e s ig na tion of the g a s d is tribution a nd tra ns m is s ionnetwork (“the Inform a tion”). Any re pre s e ntations a nd wa rra ntie s expre s s orim plie d , a re exclud e d to the fulle s t exte nt pe rm itte d by law. No lia bility s ha ll beacce pte d for a ny los s or d a m a g e includ ing , without lim itation, d irect, ind irect,s pecia l, incid e nta l, punitive or cons e que ntia l los s includ ing los s of profits,a ris ing out of or in connection with the us e of the Inform ation (includ ing m a ps orm a pping d a ta). NO TE: DIAL BEFO RE Y O U DIG Phone 1850 427 747 or e-m a ild ig @g a s ne tworks .ie – The a ctua l pos ition of the g a s /e lectricity d is tribution a ndtra ns m is s ion network m ust be ve rifie d on s ite be fore a ny m echa nica lexcavating ta ke s pla ce. If a ny m echa nica l exca vation is propos e d , ha rd copym a ps m ust be re que s te d from GNI re g a s . All work in the vicinity of the g a sd is tribution a nd tra ns m is s ion ne twork m ust be com ple te d in a ccord a nce withthe curre nt e d ition of the He a lth & Sa fe ty Authority publica tion, ‘Cod e ofPractice For Avoid ing Da ng e r From Und e rg round Se rvice s ’ which is a va ila blefrom the He a lth a nd Sa fe ty Authority (1890 28 93 89) or ca n be d ownloa d e dfre e of cha rg e at www.hs a.ie.”

´

S u b j e c t t o C o n t r a c t / C o n t r a c t D e n i e d – F o r I d e n t i f i c a t i o n P u r p o s e s o n l y




APPENDIX B

Irish Water Pre-Connection Enquiry Response & Certificate of Design Acceptance




APPENDIX D

Permissible Discharge Calculations

Discharge and Long-Term Storage

PROJECT JOB REF.

Proposed Residential Development at Church Road, Killiney 180153

SUBJECT Calc. Sheet No.

Surface Water Calculations - Permissible Site Discharge 1

Drawing ref. Calculations by Checked by Date

180153-3000 LMCL SVC 31.05.2019

PERMISSIBLE SURFACE WATER DISCHARGE CALCULATIONS

Site Area

What is the overall catchment area? 1.48 Hectares (ha) Site is Less than 50 Hectares

Pre-Development Catchment Soil Characteristics

Are there different soil types present on the pre-developed site? No

Catchment This refers to the entire site area 1 SOIL SOIL Value SPR

Area 1.48 Hectares (ha) 1 0.15 0.10

Drainage Group 2 Class 2 0.30 0.30

Depth to Impermeable Layers 2 Class 3 0.40 0.37

Permeability Group above Impermeable Layers 2 Class 4 0.45 0.47

Slope (o)2 Class 5 0.50 0.53

SOIL Type 4 From FSR Table1SOIL Index 0.45

Site SOIL Index Value 0.45

Site SPR Value 0.47

Post-Development Catchment Characteristics

Is the development divided into sub-catchments? No

What is the overall site area for catchment? 1.48 Hectares (ha)

Overall Catchment Area (m2) Runoff Coeff. Effective Area (m2)

Roofs - Type 1 (Traditional) 4866 1.00 4866.0

Roofs - Type 2 (Draining to SUDS features) 0 0.75 0.0

Green Roofs 2707 0.85 2301.0

Roads and Footpaths - Type 1 (Draining to gullies) 985 0.95 935.8

Roads and Footpaths - Type 2 (Draining to Suds features) 1029 0.70 720.3

Paved Areas 0 0.95 0.0

Permeable Paving 665 0.50 332.5

Bioretention Areas 0 0.70 0.0

Grassed Areas 1374 0.47 645.8

Public Open Space 3182 0.47 1495.5

Include Public Open Space in Effective Catchment Area? No Assumed open space area does not drain to surface water network

Effective Catchment Area 9801.3 m2

Effective Catchment Runoff Coefficient 0.84

Long-Term Storage

Is long-term Storage provided? No

Permissible Site Discharge

What is the Standard Average Annual Rainfall (SAAR)? 813.0 mm From Met Eireann, Co-ordinates xxxxxxxx, xxxxxxxxx

Is the overall site area less than 50 hectares? Yes

5QBARRural calculated for 50 ha and linearly interpolated for area of site 7.7 Litres/sec

7Site Discharge = 7.7 Litres/sec

Notes and Formulae

1. SOIL index value calculated from Flood Studies Report - The Classification of Soils from Winter Rainfall Acceptance Rate (Table 4.5).

2. SPR value calculated from GDSDS - Table 6.7.

3. Rainfall depth for 100 year return period, 6 hour duration with additional 10% for climate change.

4. Long-term storage Volxs (m3) = Rainfall.Area.10.[(PIMP/100)(0.8.a)+(1-PIMP/100)(b.SPR)-SPR]. (GDSDS Section 6.7.3).

Where long-term storage cannot be provided on-site due to ground conditions, Total Permissible Outflow is to be kept to QBAR (Rural).

5. Total Permissible Outflow - QBAR (Rural) calculated in accordance with GDSDS - Regional Drainage Policies

(Volume 2 - Chapter 6), i.e. QBAR(m3/s)=0.00108x(Area)0.89(SAAR)1.17(SOIL)2.17 - For catchments greater than 50 hectares in area. Flow rates are linearly interpolated for areas samller than 50hectares.

6. Where Total Permissible Outflow is less than 2.0l/s and not achievable, use 2.0 l/s or closest value possible.

7. QBAR multiplied by growth factors of 0.85 for 1 year, 2.1 for 30 year and 2.6 for 100 year return period events, from GDSDS Figure C2.

180153-Permissible Site Discharge

Soil Characteristics

PROJECT JOB REF.



Surface Water Calculations - Soil Characteristics from FSR 4


180153-3000 JBK LMCL 05.03.2019

1. Soil index (SPR) value calculated from Flood Studies Report - The Classification of Soils from Winter Rainfall Acceptance Rate (Table 4.5).

180153-Permissible Site Discharge.xlsm




APPENDIX E

Surface Water Attenuation Calculations

DBFL Consulting Engineers Page 1

Ormond House CHURCHVIEW ROAD

Upper Ormond Quay 180153

Dublin 7

Date 31/05/2019 15:48 Designed by LML

File 180153- NETWORK- SHD PL... Checked by SVC

Innovyze Network 2018.1.1

STORM SEWER DESIGN by the Modified Rational Method

Design Criteria for Storm

©1982-2018 Innovyze

Pipe Sizes STANDARD Manhole Sizes STANDARD

FSR Rainfall Model - Scotland and IrelandReturn Period (years) 100 PIMP (%) 84

M5-60 (mm) 15.700 Add Flow / Climate Change (%) 0Ratio R 0.280 Minimum Backdrop Height (m) 0.200

Maximum Rainfall (mm/hr) 50 Maximum Backdrop Height (m) 1.500Maximum Time of Concentration (mins) 30 Min Design Depth for Optimisation (m) 1.200

Foul Sewage (l/s/ha) 0.000 Min Vel for Auto Design only (m/s) 1.00Volumetric Runoff Coeff. 0.750 Min Slope for Optimisation (1:X) 500

Designed with Level Inverts

Simulation Criteria for Storm

Volumetric Runoff Coeff 0.750 Additional Flow - % of Total Flow 0.000Areal Reduction Factor 1.000 MADD Factor * 10m³/ha Storage 0.000

Hot Start (mins) 0 Inlet Coeffiecient 0.800Hot Start Level (mm) 0 Flow per Person per Day (l/per/day) 0.000

Manhole Headloss Coeff (Global) 0.500 Run Time (mins) 60Foul Sewage per hectare (l/s) 0.000 Output Interval (mins) 1

Number of Input Hydrographs 0 Number of Storage Structures 2Number of Online Controls 2 Number of Time/Area Diagrams 0Number of Offline Controls 0 Number of Real Time Controls 0

Synthetic Rainfall Details

Rainfall Model FSR Profile Type SummerReturn Period (years) 100 Cv (Summer) 0.750

Region Scotland and Ireland Cv (Winter) 0.840M5-60 (mm) 15.700 Storm Duration (mins) 30

Ratio R 0.280




Dublin 7




Online Controls for Storm


Hydro-Brake® Optimum Manhole: S12, DS/PN: S1.006, Volume (m³): 4.4

Unit Reference MD-SHE-0095-6000-2570-6000Design Head (m) 2.570

Design Flow (l/s) 6.0Flush-Flo™ CalculatedObjective Minimise upstream storage

Application SurfaceSump Available YesDiameter (mm) 95

Invert Level (m) 47.630Minimum Outlet Pipe Diameter (mm) 150Suggested Manhole Diameter (mm) 1200

Control Points Head (m) Flow (l/s)

Design Point (Calculated) 2.570 6.0Flush-Flo™ 0.416 4.5Kick-Flo® 0.846 3.6

Mean Flow over Head Range - 4.6

The hydrological calculations have been based on the Head/Discharge relationship for theHydro-Brake® Optimum as specified. Should another type of control device other than aHydro-Brake Optimum® be utilised then these storage routing calculations will beinvalidated

Depth (m) Flow (l/s) Depth (m) Flow (l/s) Depth (m) Flow (l/s) Depth (m) Flow (l/s)

0.100 3.0 1.200 4.2 3.000 6.4 7.000 9.60.200 4.1 1.400 4.5 3.500 6.9 7.500 9.90.300 4.4 1.600 4.8 4.000 7.4 8.000 10.20.400 4.5 1.800 5.1 4.500 7.8 8.500 10.50.500 4.4 2.000 5.3 5.000 8.2 9.000 10.80.600 4.3 2.200 5.6 5.500 8.6 9.500 11.10.800 3.8 2.400 5.8 6.000 8.91.000 3.9 2.600 6.0 6.500 9.3









Dublin 7











0.100 3.9 1.200 5.8 3.000 8.9 7.000 13.30.200 5.9 1.400 6.2 3.500 9.6 7.500 13.80.300 6.4 1.600 6.6 4.000 10.2 8.000 14.20.400 6.7 1.800 7.0 4.500 10.8 8.500 14.60.500 6.7 2.000 7.4 5.000 11.3 9.000 15.00.600 6.7 2.200 7.7 5.500 11.9 9.500 15.40.800 6.3 2.400 8.0 6.000 12.41.000 5.4 2.600 8.3 6.500 12.9




Dublin 7




Storage Structures for Storm


Cellular Storage Manhole: Northern Attn., DS/PN: S1.005

Invert Level (m) 47.720 Safety Factor 1.0Infiltration Coefficient Base (m/hr) 0.00000 Porosity 0.62Infiltration Coefficient Side (m/hr) 0.00000

Depth (m) Area (m²) Inf. Area (m²) Depth (m) Area (m²) Inf. Area (m²)

0.000 352.0 0.0 1.300 0.0 0.00.100 352.0 0.0 1.400 0.0 0.00.200 352.0 0.0 1.500 0.0 0.00.300 352.0 0.0 1.600 0.0 0.00.400 352.0 0.0 1.700 0.0 0.00.500 352.0 0.0 1.800 0.0 0.00.600 352.0 0.0 1.900 0.0 0.00.700 352.0 0.0 2.000 0.0 0.00.800 352.0 0.0 2.100 0.0 0.00.900 352.0 0.0 2.200 0.0 0.01.000 352.0 0.0 2.300 0.0 0.01.062 352.0 0.0 2.400 0.0 0.01.063 0.0 0.0 2.500 0.0 0.0

Cellular Storage Manhole: Southern Attn., DS/PN: S1.012



0.000 200.0 0.0 1.300 0.0 0.00.100 200.0 0.0 1.400 0.0 0.00.200 200.0 0.0 1.500 0.0 0.00.300 200.0 0.0 1.600 0.0 0.00.400 200.0 0.0 1.700 0.0 0.00.500 200.0 0.0 1.800 0.0 0.00.600 200.0 0.0 1.900 0.0 0.00.700 200.0 0.0 2.000 0.0 0.00.800 200.0 0.0 2.100 0.0 0.00.900 200.0 0.0 2.200 0.0 0.01.000 200.0 0.0 2.300 0.0 0.01.062 200.0 0.0 2.400 0.0 0.01.063 0.0 0.0 2.500 0.0 0.0




Dublin 7




Summary of Critical Results by Maximum Level (Rank 1) for Storm


Simulation CriteriaAreal Reduction Factor 1.000 Additional Flow - % of Total Flow 0.000

Hot Start (mins) 0 MADD Factor * 10m³/ha Storage 0.000Hot Start Level (mm) 0 Inlet Coeffiecient 0.800

Manhole Headloss Coeff (Global) 0.500 Flow per Person per Day (l/per/day) 0.000Foul Sewage per hectare (l/s) 0.000


Synthetic Rainfall DetailsRainfall Model FSR Ratio R 0.280

Region Scotland and Ireland Cv (Summer) 0.750M5-60 (mm) 15.700 Cv (Winter) 0.840

Margin for Flood Risk Warning (mm) 300.0Analysis Timestep 2.5 Second Increment (Extended)

DTS Status ONDVD Status OFF

Inertia Status OFF

Profile(s) Summer and WinterDuration(s) (mins) 15, 30, 60, 120, 180, 240, 360, 480, 600,

720, 960, 1440, 2160, 2880, 4320, 5760,7200, 8640, 10080

Return Period(s) (years) 100Climate Change (%) 10

PN

US/MH

Name Storm

Return

Period

Climate

Change

First (X)

Surcharge

First (Y)

Flood

First (Z)

Overflow

S1.000 S17 15 Winter 100 +10% 100/15 SummerS1.001 S16 15 Winter 100 +10% 100/15 SummerS1.002 S15 15 Winter 100 +10% 100/15 SummerS1.003 S14 15 Winter 100 +10% 100/15 SummerS1.004 S13 480 Winter 100 +10% 100/15 SummerS2.000 S13.1 480 Winter 100 +10% 100/15 SummerS1.005 Northern Attn. 480 Winter 100 +10% 100/15 WinterS1.006 S12 480 Winter 100 +10% 100/15 SummerS1.007 S11 360 Winter 100 +10% 100/30 SummerS1.008 S10 360 Winter 100 +10% 100/30 SummerS1.009 S9 360 Winter 100 +10% 100/15 SummerS1.010 S8 360 Winter 100 +10% 100/15 SummerS1.011 S7 360 Winter 100 +10% 100/15 SummerS3.000 S7.1 360 Winter 100 +10% 100/15 SummerS1.012 Southern Attn. 360 Winter 100 +10% 100/15 SummerS1.013 S6 360 Winter 100 +10% 100/15 SummerS1.014 S5 360 Winter 100 +10% 100/15 SummerS1.015 S4 360 Winter 100 +10% 100/15 Summer




Dublin 7






PN

US/MH

Name

Overflow

Act.

Water

Level

(m)

Surcharged

Depth

(m)

Flooded

Volume

(m³)

Flow /

Cap.

Overflow

(l/s)

Pipe

Flow

(l/s) Status

S1.000 S17 49.616 1.071 0.000 1.04 34.1 FLOOD RISKS1.001 S16 49.547 1.067 0.000 1.37 68.4 SURCHARGEDS1.002 S15 49.027 0.826 0.000 2.46 74.4 FLOOD RISKS1.003 S14 48.732 0.579 0.000 2.30 74.7 SURCHARGEDS1.004 S13 48.664 0.531 0.000 0.22 16.9 SURCHARGEDS2.000 S13.1 48.662 0.637 0.000 0.15 5.4 SURCHARGEDS1.005 Northern Attn. 48.662 0.642 0.000 0.26 17.4 SURCHARGEDS1.006 S12 49.053 1.198 0.000 0.14 4.4 SURCHARGEDS1.007 S11 49.070 1.305 0.000 0.17 5.2 SURCHARGEDS1.008 S10 49.082 1.364 0.000 0.19 6.6 SURCHARGEDS1.009 S9 49.098 1.590 0.000 0.24 7.8 SURCHARGEDS1.010 S8 49.108 1.697 0.000 0.30 7.8 SURCHARGEDS1.011 S7 49.113 1.655 0.000 0.27 16.8 FLOOD RISKS3.000 S7.1 49.119 1.044 0.000 0.27 8.8 SURCHARGEDS1.012 Southern Attn. 49.112 1.714 0.000 1.25 75.1 SURCHARGEDS1.013 S6 49.108 1.770 0.000 1.16 65.1 SURCHARGEDS1.014 S5 49.104 1.812 0.000 0.50 31.4 SURCHARGEDS1.015 S4 49.097 1.905 0.000 0.08 7.7 SURCHARGED

PN

US/MH

Name

Level

Exceeded

S1.000 S17S1.001 S16S1.002 S15S1.003 S14S1.004 S13S2.000 S13.1S1.005 Northern Attn.S1.006 S12S1.007 S11S1.008 S10S1.009 S9S1.010 S8S1.011 S7S3.000 S7.1S1.012 Southern Attn.S1.013 S6S1.014 S5S1.015 S4

currans

Rectangle

currans

Text Box

Discharge rate from the site




Dublin 7






PN

US/MH

Name Storm

Return

Period

Climate

Change

First (X)

Surcharge

First (Y)

Flood

First (Z)

Overflow

Overflow

Act.

Water

Level

(m)

S1.016 S3 360 Winter 100 +10% 46.811S1.017 S2 360 Winter 100 +10% 46.750S1.018 S1 360 Winter 100 +10% 46.447

PN

US/MH

Name

Surcharged

Depth

(m)

Flooded

Volume

(m³)

Flow /

Cap.

Overflow

(l/s)

Pipe

Flow

(l/s) Status

Level

Exceeded

S1.016 S3 -0.144 0.000 0.28 7.7 OKS1.017 S2 -0.161 0.000 0.18 7.7 OKS1.018 S1 -0.149 0.000 0.25 7.7 OK




APPENDIX F

Surface Water Interception Volume Calculations

Interception Volume

PROJECT JOB REF.



Surface Water Calculations - Interception Volume 3


180153-3000 LMCL SVC 31.05.2019

SURFACE WATER CALCULATIONS

Site Area

Total Site Area = 1.48 Hectares (ha)

Interception Volume (Post-Development)

Impermeable Area = 0.75 Hectares (ha)

Rainfall Depth = 5 mm1Interception Volume = 30.2 m3

Notes

1. Interception Volume (m3) = Impermeable Area (ha) x 5mm x 10 (GDSDS Section 6.3.1.2.1). For sites where a pond is applicable.

80% runoff from impermeable areas assumed.





APPENDIX G

Surface Water Treatment Volume Calculations

Treatment Volume

PROJECT JOB REF.



Surface Water Calculations - Treatment Volume 2


180153-3000 LMCL SVC 31.05.2019

SURFACE WATER CALCULATIONS

Site Area

Total Site Area = 1.48 Hectares (ha)

Treatment Volume (Post-Development)

Impermeable Area = 0.755 Hectares (ha)

Rainfall Depth = 15 mm1Treatment Volume (Vt) = 90.5 m3

Notes

1. Treatment Volume Vt (m3) = Impermeable Area (ha) x 15mm x 10 (GDSDS Section 6.3.1.2.1). For sites where a pond is applicable.

80% runoff from impermeable areas assumed.





APPENDIX H

SuDS Summary

TITLE Job Reference

Proposed Residential Development at Church, Killiney 180153


GREEN ROOF DESIGN 1

DRAWING NUMBER Calculations by Checked by Date

180153-3000 LMCL SVC 31.05.2019

INPUT DATA

Green Roof Area (A) 2707.0 m2

Total Roof Area 4511.0 m2

.1Filter Layer Depth (d) 0.250 m % Green Roof Area 60 %

1Filter Layer Voids Ratio (η) 30.0 %

TREATMENT VOLUME

203.0 m3

EVAPOTRANSPIRATION VOLUME

3Evapotranspiration Rate per Day 5.00 mm/day

13.535 m3 Provided Interception Volume

1 Filter Bed depth typically between 0.25 and 0.35m

2 Treatment Volume Vt (m3) = Green Roof Area (m2) x d x η

3 Assumed 2mm evaporation and 3mm transpiration.

Evapotranspiration Volume

2Treatment Volume (VT)

Notes:

Provided Treatment Volume

TITLE Job Reference



Permeable Paving Design 1


180153-3000 LMCL SVC 31.05.2019

FLAT SITES

INPUT DATA

Pavement Area (A) 665.0 m2

Pavement Perimeter (P) 0.0 m

Sub-base Depth (d) 0.220 m

1Sub-base Voids Ratio (η) 0.30

Sub-base Infiltration Rate per hour 1000 mm/hr

Sub-base Infiltration Rate (k) 0.278 mm/s

Subgrade Infiltration Rate per hour 0.0 mm/hr

Subgrade Infiltration Rate ( f) 0.000 mm/s

VOLUME (STORAGE AND TREATMENT)

Permeable Paving Storage Volume per m20.066 m3/m2

Total Permeable Paving Treatment Volume 43.9 m3

INFILTRATION

Approx. Permeable Paving Infiltration per m20.000 l/s/m2

2Total Permeable Paving Infiltration Rate 0.000 l/s

3Total Permeable Paving Interception Volume 0.0 m3

FLOW

Average Distance between Outlet Drains 6.0 m

Flow Velocity through Permeable Paving 0.000021 m/s

Trench Retention Time 79.1 hr

Provided Treatment Volume

Provided Interception Volume

TITLE Job Reference



Permeable Paving Design 1


180153-3000 LMCL SVC 31.05.2019

1 Sub-base material has a void ratio of approximately 30%, Table: 3

source 'BRE Digest 365'. Material Infiltration Rate (mm/hr)

2 Wetted perimeter assuming 50% of trench depth, source 'BRE Digest 365'. Gravel 10 - 1000

3 Volume calculated using 6 hour storm event. Sand 0.1 - 100

4 For Paving on slopes includes infiltration, provide 500mmx500mm trenches Loamy sand 0.01 - 1

at 10m centres along slope with 1000mmx500mm at base of slope. Sandy loam 0.05 - 0.5

source 'Formpave - Aquaflow Permeable Paving System'. Loam 0.001 - 0.1

Silt loam 0.0005 - 0.005

Table: 1 Chalk 0.001 - 100

Sandy clay loam 0.001 - 0.01

Silty clay loam 0.00005 - 0.005

Clay < 0.0001

Till 0.00001 - 0.01

Rock 0.00001 - 1

Cutoff point for most infiltration drainage systems = 0.001 mm/hr

Table: 2

Total Trench Infiltration:= 1/2 . D . L . f

where:L = LengthD = Depth to Invert

f = Subgrade infiltration rate

Total Permeable Paving Outflow:

= A . k . i

where:A = Cross Sectional Area of Subbasek = Subbase Infiltration Ratei = Hydraulic Gradient

Hydraulic gradient has been assumed as the pavement gradient

with an additional 250mm fall per 100m length.

Footpath

Effective Depths are provided from source 'Formpave -

Aquaflow Permeable Paving System' and may subject to

change as per site requirement.

0.20

Uniform gravel 0.30 - 0.40

Source: The SUDS manual, Published by CIRIA.

Effective Depth (m)Pavement Type

0.40Car-Parking

Source: Microdrainage

Notes:

Graded sand or gravel 0.20 - 0.30

Material void Ratio, ηClean stone 0.40 - 0.50

TITLE Job Reference

Proposed Residential Development at Church Road Killiney 180153


Swale No. 1 Channel Design 1


180153-3000 LMCL SVC 31.05.2019

INPUT DATA

Side Slopes 4.0 1 in ….

Bottom width (W) 0.50 m

Depth to Invert (D) 0.15 m

Length (L) 30.7 m

Slope (S) 79 1 in ….

Manning's Coefficient (n) 0.030



TREATMENT VOLUME

53.3 m2

1Depth of Subgrade Treatment 0.20 m

10.66 m3

STORAGE VOLUME

11.9 m

0.80 m3

2.40 m3

INFILTRATION

0.00 l/s

0.00 m3

``

FLOW

Maximum Swale Flow at Outlet 128.8 l/s

Maximum Swale Velocity at Outlet 0.78 m/s

3Typical Swale Retention Time 0.011 hr

1 Assume 200mm of topsoil.

2 Volume calculated using 6 hour storm event.

3 Swale retention time depends on outlet control, refer to WINDES Model.

Table: 1

Total Swale Infiltration = P . L . f

where:

P = Wetted Perimeter

L = Length


Total Swale Flow = 1/n.AR 2/3 S 1/2

where:

A = Area of flow

P = Wetted perimeter

R = A/P Cutoff point for most infiltration drainage systems = 0.001 mm/hr

n = Manning's Coefficient

s = Slope

0.001 - 100

0.001 - 0.01

Max. Length of Storage within Swale

Total Plan Area of Swale

Total Swale Treatment Volume (VT)

Infiltration Rate (mm/hr)

10 - 1000

Swale Storage Volume (V)

0.01 - 1

0.05 - 0.5


Clay < 0.0001

Sandy clay loam

0.00005 - 0.005Silty clay loam

Notes:

Sandy loam

Sand

Swale Storage Volume per 12m Length

Total Swale Infiltration Rate

Loamy sand

Gravel

Material

3Total Swale Infiltration Volume

0.1 - 100

0.00001 - 1Rock

0.00001 - 0.01Till

Loam

Silt loam

0.001 - 0.1

0.0005 - 0.005

Chalk

TITLE Job Reference



Swale No.2 Channel Design 2


180153-3000 LMCL SVC 31.05.2019

INPUT DATA




Length (L) 17.5 m

Slope (S) 106 1 in ….




TREATMENT VOLUME

30.4 m2


6.08 m3

STORAGE VOLUME

15.9 m

1.07 m3

1.07 m3

INFILTRATION

0.00 l/s

0.00 m3

``

FLOW







Table: 1


where:


L = Length



where:

A = Area of flow




s = Slope

0.001 - 100

0.001 - 0.01





10 - 1000


0.01 - 1

0.05 - 0.5


Clay < 0.0001

Sandy clay loam


Notes:

Sandy loam

Sand



Loamy sand

Gravel

Material


0.1 - 100

0.00001 - 1Rock

0.00001 - 0.01Till

Loam

Silt loam

0.001 - 0.1

0.0005 - 0.005

Chalk

TITLE Job Reference



Swale No.3 Channel Design 1


180153-3000 LMCL SVC 31.05.2019

INPUT DATA




Length (L) 38.8 m

Slope (S) 137 1 in ….




TREATMENT VOLUME

67.4 m2


13.48 m3

STORAGE VOLUME

20.6 m

1.39 m3

2.77 m3

INFILTRATION

0.00 l/s

0.00 m3

``

FLOW







Table: 1


where:


L = Length



where:

A = Area of flow




s = Slope

0.1 - 100

0.00001 - 1Rock

0.00001 - 0.01Till

Loam

Silt loam

0.001 - 0.1

0.0005 - 0.005

Chalk

Notes:

Sandy loam

Sand



Loamy sand

Gravel

Material



Clay < 0.0001

Sandy clay loam


0.001 - 100

0.001 - 0.01





10 - 1000


0.01 - 1

0.05 - 0.5

TITLE Job Reference



Interception/Treatment Volume Summary 1


180153-3000 LMCL SVC 31.05.19

INPUT DATA

Interception Volume Required 30.2 m3

Treatment Volume Required 90.5 m3

Catchment Interception Volumes Treatment Volumes

Swales 0.0 m3

30.2 m3

Bio-Retention 0.0 m3

0.0 m3

Permeable Paving 0.0 m3

43.9 m3

Filter Drain 0.0 m30.0 m3

Green Roofs 13.5 m3203.0 m3

Bio Pond 0.0 m3

0.0 m3

Stormtech Isolator Row 0.0 m30.0 m3

Total Volumes Provided 13.5 m3277.1 m3

Check Provided Volumes are greater FAIL PASS

than Required Volumes




APPENDIX I

Surface Water Sewers Calculations




Dublin 7




STORM SEWER DESIGN by the Modified Rational Method

Design Criteria for Storm


Pipe Sizes STANDARD Manhole Sizes STANDARD

FSR Rainfall Model - Scotland and IrelandReturn Period (years) 100 PIMP (%) 84

M5-60 (mm) 15.700 Add Flow / Climate Change (%) 0Ratio R 0.280 Minimum Backdrop Height (m) 0.200

Maximum Rainfall (mm/hr) 50 Maximum Backdrop Height (m) 1.500Maximum Time of Concentration (mins) 30 Min Design Depth for Optimisation (m) 1.200

Foul Sewage (l/s/ha) 0.000 Min Vel for Auto Design only (m/s) 1.00Volumetric Runoff Coeff. 0.750 Min Slope for Optimisation (1:X) 500

Designed with Level Inverts

Network Design Table for Storm

PN Length

(m)

Fall

(m)

Slope

(1:X)

I.Area

(ha)

T.E.

(mins)

Base

Flow (l/s)

k

(mm)

HYD

SECT

DIA

(mm)

Section Type Auto

Design

S1.000 11.731 0.065 180.5 0.113 4.00 0.0 0.600 o 225 Pipe/ConduitS1.001 25.951 0.279 93.0 0.113 0.00 0.0 0.600 o 225 Pipe/ConduitS1.002 9.661 0.048 201.3 0.024 0.00 0.0 0.600 o 225 Pipe/ConduitS1.003 19.857 0.095 209.0 0.000 0.00 0.0 0.600 o 225 Pipe/ConduitS1.004 17.334 0.113 153.4 0.113 0.00 0.0 0.600 o 300 Pipe/Conduit

S2.000 12.415 0.080 155.2 0.113 4.00 0.0 0.600 o 225 Pipe/Conduit

S1.005 17.807 0.090 197.9 0.000 0.00 0.0 0.600 o 300 Pipe/ConduitS1.006 19.350 0.090 215.0 0.000 0.00 0.0 0.600 o 225 Pipe/ConduitS1.007 9.892 0.047 210.5 0.000 0.00 0.0 0.600 o 225 Pipe/ConduitS1.008 44.153 0.210 210.3 0.049 0.00 0.0 0.600 o 225 Pipe/ConduitS1.009 20.970 0.097 216.2 0.029 0.00 0.0 0.600 o 225 Pipe/Conduit

Network Results Table

PN Rain

(mm/hr)

T.C.

(mins)

US/IL

(m)

Σ I.Area

(ha)

Σ Base

Flow (l/s)

Foul

(l/s)

Add Flow

(l/s)

Vel

(m/s)

Cap

(l/s)

Flow

(l/s)

S1.000 50.00 4.20 48.320 0.113 0.0 0.0 0.0 0.97 38.6 15.2S1.001 50.00 4.52 48.255 0.226 0.0 0.0 0.0 1.36 53.9 30.6S1.002 50.00 4.70 47.976 0.250 0.0 0.0 0.0 0.92 36.5 33.9S1.003 50.00 5.06 47.928 0.250 0.0 0.0 0.0 0.90 35.8 33.9S1.004 50.00 5.29 47.833 0.363 0.0 0.0 0.0 1.27 89.6 49.1

S2.000 50.00 4.20 47.800 0.113 0.0 0.0 0.0 1.05 41.6 15.2

S1.005 50.00 5.56 47.720 0.475 0.0 0.0 0.0 1.11 78.8 64.4S1.006 50.00 4.36 47.630 0.000 6.0 0.0 0.0 0.89 35.3 6.0S1.007 50.00 4.55 47.540 0.000 6.0 0.0 0.0 0.90 35.7 6.0S1.008 50.00 5.37 47.493 0.049 6.0 0.0 0.0 0.90 35.7 12.6S1.009 50.00 5.76 47.283 0.078 6.0 0.0 0.0 0.89 35.2 16.6

currans

Rectangle

currans

Text Box

Outfall from the upper Attn Tank




Dublin 7




Network Design Table for Storm


PN Length

(m)

Fall

(m)

Slope

(1:X)

I.Area

(ha)

T.E.

(mins)

Base

Flow (l/s)

k

(mm)

HYD

SECT

DIA

(mm)

Section Type Auto

Design

S1.010 6.533 0.028 233.3 0.000 0.00 0.0 0.600 o 225 Pipe/ConduitS1.011 13.274 0.060 221.2 0.149 0.00 0.0 0.600 o 300 Pipe/Conduit

S3.000 16.054 0.079 203.2 0.149 4.00 0.0 0.600 o 225 Pipe/Conduit

S1.012 13.878 0.060 231.3 0.000 0.00 0.0 0.600 o 300 Pipe/ConduitS1.013 11.530 0.046 250.7 0.000 0.00 0.0 0.600 o 300 Pipe/ConduitS1.014 25.011 0.100 250.1 0.086 0.00 0.0 0.600 o 300 Pipe/ConduitS1.015 14.606 0.162 90.2 0.039 0.00 0.0 0.600 o 300 Pipe/ConduitS1.016 11.038 0.044 250.9 0.000 0.00 0.0 0.600 o 225 Pipe/ConduitS1.017 42.527 0.315 135.0 0.000 0.00 0.0 0.600 o 225 Pipe/ConduitS1.018 23.306 0.100 233.1 0.000 0.00 0.0 0.600 o 225 Pipe/Conduit

Network Results Table

PN Rain

(mm/hr)

T.C.

(mins)

US/IL

(m)

Σ I.Area

(ha)

Σ Base

Flow (l/s)

Foul

(l/s)

Add Flow

(l/s)

Vel

(m/s)

Cap

(l/s)

Flow

(l/s)

S1.010 50.00 5.89 47.186 0.078 6.0 0.0 0.0 0.85 33.9 16.6S1.011 50.00 6.10 47.158 0.227 6.0 0.0 0.0 1.05 74.4 36.7

S3.000 50.00 4.29 47.850 0.149 0.0 0.0 0.0 0.91 36.3 20.1

S1.012 50.00 6.32 47.098 0.375 6.0 0.0 0.0 1.03 72.8 56.8S1.013 50.00 6.52 47.038 0.375 6.0 0.0 0.0 0.99 69.9 56.8S1.014 50.00 6.94 46.992 0.461 6.0 0.0 0.0 0.99 70.0 68.4S1.015 50.00 4.15 46.892 0.000 7.7 0.0 0.0 1.66 117.1 7.7S1.016 50.00 4.37 46.730 0.000 7.7 0.0 0.0 0.82 32.6 7.7S1.017 50.00 5.00 46.686 0.000 7.7 0.0 0.0 1.12 44.7 7.7S1.018 50.00 5.46 46.371 0.000 7.7 0.0 0.0 0.85 33.9 7.7

currans

Rectangle

currans

Text Box

Discharge rate from the site




Dublin 7




Manhole Schedules for Storm


MH

Name

MH

CL (m)

MH

Depth

(m)

MH

Connection

MH

Diam.,L*W

(mm)

PN

Pipe Out

Invert

Level (m)

Diameter

(mm)

PN

Pipes In

Invert

Level (m)

Diameter

(mm)

B

S17 49.650 1.330 Open Manhole 1200 S1.000 48.320 225

S16 49.900 1.645 Open Manhole 1200 S1.001 48.255 225 S1.000 48.255 225

S15 49.280 1.304 Open Manhole 1200 S1.002 47.976 225 S1.001 47.976 225

S14 49.900 1.972 Open Manhole 1200 S1.003 47.928 225 S1.002 47.928 225

S13 50.500 2.667 Open Manhole 1200 S1.004 47.833 300 S1.003 47.833 225

S13.1 51.650 3.850 Open Manhole 1200 S2.000 47.800 225

Northern Attn. 50.500 2.780 Open Manhole 1200 S1.005 47.720 300 S1.004 47.720 300

S2.000 47.720 225

S12 50.500 2.870 Open Manhole 1200 S1.006 47.630 225 S1.005 47.630 300

S11 49.800 2.260 Open Manhole 1200 S1.007 47.540 225 S1.006 47.540 225

S10 49.400 1.907 Open Manhole 1200 S1.008 47.493 225 S1.007 47.493 225

S9 49.600 2.317 Open Manhole 1200 S1.009 47.283 225 S1.008 47.283 225

S8 49.870 2.684 Open Manhole 1200 S1.010 47.186 225 S1.009 47.186 225

S7 49.150 1.992 Open Manhole 1200 S1.011 47.158 300 S1.010 47.158 225

S7.1 50.450 2.600 Open Manhole 1200 S3.000 47.850 225

Southern Attn. 49.650 2.552 Open Manhole 1200 S1.012 47.098 300 S1.011 47.098 300

S3.000 47.771 225

S6 49.830 2.792 Open Manhole 1200 S1.013 47.038 300 S1.012 47.038 300

S5 49.820 2.828 Open Manhole 1200 S1.014 46.992 300 S1.013 46.992 300

S4 49.400 2.508 Open Manhole 1200 S1.015 46.892 300 S1.014 46.892 300

S3 49.410 2.680 Open Manhole 1200 S1.016 46.730 225 S1.015 46.730 300

S2 48.960 2.274 Open Manhole 1200 S1.017 46.686 225 S1.016 46.686 225

S1 47.450 1.079 Open Manhole 1200 S1.018 46.371 225 S1.017 46.371 225

ExSMH 47.070 0.799 Open Manhole 1200 OUTFALL S1.018 46.271 225




Dublin 7




PIPELINE SCHEDULES for Storm

Upstream Manhole


PN Hyd

Sect

Diam

(mm)

MH

Name

C.Level

(m)

I.Level

(m)

D.Depth

(m)

MH

Connection

MH DIAM., L*W

(mm)

S1.000 o 225 S17 49.650 48.320 1.105 Open Manhole 1200S1.001 o 225 S16 49.900 48.255 1.420 Open Manhole 1200S1.002 o 225 S15 49.280 47.976 1.079 Open Manhole 1200S1.003 o 225 S14 49.900 47.928 1.747 Open Manhole 1200S1.004 o 300 S13 50.500 47.833 2.367 Open Manhole 1200

S2.000 o 225 S13.1 51.650 47.800 3.625 Open Manhole 1200

S1.005 o 300 Northern Attn. 50.500 47.720 2.480 Open Manhole 1200S1.006 o 225 S12 50.500 47.630 2.645 Open Manhole 1200S1.007 o 225 S11 49.800 47.540 2.035 Open Manhole 1200S1.008 o 225 S10 49.400 47.493 1.682 Open Manhole 1200S1.009 o 225 S9 49.600 47.283 2.092 Open Manhole 1200S1.010 o 225 S8 49.870 47.186 2.459 Open Manhole 1200S1.011 o 300 S7 49.150 47.158 1.692 Open Manhole 1200

S3.000 o 225 S7.1 50.450 47.850 2.375 Open Manhole 1200

S1.012 o 300 Southern Attn. 49.650 47.098 2.252 Open Manhole 1200S1.013 o 300 S6 49.830 47.038 2.492 Open Manhole 1200S1.014 o 300 S5 49.820 46.992 2.528 Open Manhole 1200

Downstream Manhole

PN Length

(m)

Slope

(1:X)

MH

Name

C.Level

(m)

I.Level

(m)

D.Depth

(m)

MH

Connection

MH DIAM., L*W

(mm)

S1.000 11.731 180.5 S16 49.900 48.255 1.420 Open Manhole 1200S1.001 25.951 93.0 S15 49.280 47.976 1.079 Open Manhole 1200S1.002 9.661 201.3 S14 49.900 47.928 1.747 Open Manhole 1200S1.003 19.857 209.0 S13 50.500 47.833 2.442 Open Manhole 1200S1.004 17.334 153.4 Northern Attn. 50.500 47.720 2.480 Open Manhole 1200

S2.000 12.415 155.2 Northern Attn. 50.500 47.720 2.555 Open Manhole 1200

S1.005 17.807 197.9 S12 50.500 47.630 2.570 Open Manhole 1200S1.006 19.350 215.0 S11 49.800 47.540 2.035 Open Manhole 1200S1.007 9.892 210.5 S10 49.400 47.493 1.682 Open Manhole 1200S1.008 44.153 210.3 S9 49.600 47.283 2.092 Open Manhole 1200S1.009 20.970 216.2 S8 49.870 47.186 2.459 Open Manhole 1200S1.010 6.533 233.3 S7 49.150 47.158 1.767 Open Manhole 1200S1.011 13.274 221.2 Southern Attn. 49.650 47.098 2.252 Open Manhole 1200

S3.000 16.054 203.2 Southern Attn. 49.650 47.771 1.654 Open Manhole 1200

S1.012 13.878 231.3 S6 49.830 47.038 2.492 Open Manhole 1200S1.013 11.530 250.7 S5 49.820 46.992 2.528 Open Manhole 1200S1.014 25.011 250.1 S4 49.400 46.892 2.208 Open Manhole 1200




Dublin 7




PIPELINE SCHEDULES for Storm

Upstream Manhole


PN Hyd

Sect

Diam

(mm)

MH

Name

C.Level

(m)

I.Level

(m)

D.Depth

(m)

MH

Connection

MH DIAM., L*W

(mm)

S1.015 o 300 S4 49.400 46.892 2.208 Open Manhole 1200S1.016 o 225 S3 49.410 46.730 2.455 Open Manhole 1200S1.017 o 225 S2 48.960 46.686 2.049 Open Manhole 1200S1.018 o 225 S1 47.450 46.371 0.854 Open Manhole 1200

Downstream Manhole

PN Length

(m)

Slope

(1:X)

MH

Name

C.Level

(m)

I.Level

(m)

D.Depth

(m)

MH

Connection

MH DIAM., L*W

(mm)

S1.015 14.606 90.2 S3 49.410 46.730 2.380 Open Manhole 1200S1.016 11.038 250.9 S2 48.960 46.686 2.049 Open Manhole 1200S1.017 42.527 135.0 S1 47.450 46.371 0.854 Open Manhole 1200S1.018 23.306 233.1 ExSMH 47.070 46.271 0.574 Open Manhole 1200

Free Flowing Outfall Details for Storm

Outfall

Pipe Number

Outfall

Name

C. Level

(m)

I. Level

(m)

Min

I. Level

(m)

D,L

(mm)

W

(mm)

S1.018 ExSMH 47.070 46.271 46.270 1200 0




Dublin 7




Online Controls for Storm












0.100 3.0 1.200 4.2 3.000 6.4 7.000 9.60.200 4.1 1.400 4.5 3.500 6.9 7.500 9.90.300 4.4 1.600 4.8 4.000 7.4 8.000 10.20.400 4.5 1.800 5.1 4.500 7.8 8.500 10.50.500 4.4 2.000 5.3 5.000 8.2 9.000 10.80.600 4.3 2.200 5.6 5.500 8.6 9.500 11.10.800 3.8 2.400 5.8 6.000 8.91.000 3.9 2.600 6.0 6.500 9.3









Dublin 7











0.100 3.9 1.200 5.8 3.000 8.9 7.000 13.30.200 5.9 1.400 6.2 3.500 9.6 7.500 13.80.300 6.4 1.600 6.6 4.000 10.2 8.000 14.20.400 6.7 1.800 7.0 4.500 10.8 8.500 14.60.500 6.7 2.000 7.4 5.000 11.3 9.000 15.00.600 6.7 2.200 7.7 5.500 11.9 9.500 15.40.800 6.3 2.400 8.0 6.000 12.41.000 5.4 2.600 8.3 6.500 12.9




Dublin 7




Storage Structures for Storm


Cellular Storage Manhole: Northern Attn., DS/PN: S1.005



0.000 352.0 0.0 1.300 0.0 0.00.100 352.0 0.0 1.400 0.0 0.00.200 352.0 0.0 1.500 0.0 0.00.300 352.0 0.0 1.600 0.0 0.00.400 352.0 0.0 1.700 0.0 0.00.500 352.0 0.0 1.800 0.0 0.00.600 352.0 0.0 1.900 0.0 0.00.700 352.0 0.0 2.000 0.0 0.00.800 352.0 0.0 2.100 0.0 0.00.900 352.0 0.0 2.200 0.0 0.01.000 352.0 0.0 2.300 0.0 0.01.062 352.0 0.0 2.400 0.0 0.01.063 0.0 0.0 2.500 0.0 0.0

Cellular Storage Manhole: Southern Attn., DS/PN: S1.012



0.000 200.0 0.0 1.300 0.0 0.00.100 200.0 0.0 1.400 0.0 0.00.200 200.0 0.0 1.500 0.0 0.00.300 200.0 0.0 1.600 0.0 0.00.400 200.0 0.0 1.700 0.0 0.00.500 200.0 0.0 1.800 0.0 0.00.600 200.0 0.0 1.900 0.0 0.00.700 200.0 0.0 2.000 0.0 0.00.800 200.0 0.0 2.100 0.0 0.00.900 200.0 0.0 2.200 0.0 0.01.000 200.0 0.0 2.300 0.0 0.01.062 200.0 0.0 2.400 0.0 0.01.063 0.0 0.0 2.500 0.0 0.0




APPENDIX M

Surcharge Analysis and Corresponding Microdrainage Results

Drainage Network Pluvial Flood Risks from Blockages: -

This is assumed to occur to a maximum of 50% blockage of the pipe network and hydrobrakes.

Pipes have been identified by microdrainage as a ‘Flood Risk’ are due to surcharged levels being

within 300mm of the cover level for the associated upstream manhole. Pipes identified as having

flooded are discussed below also. Pipes at low points and at hydobrakes are considered to be

critical.

Source Location

(Manhole)

Cover

Level

(mAOD)

Surcharged/Flood

Level (1 in 100yr)

(mAOD)+10%

Climate Change

Comments

Pluvial 1 S17 49.65 Flooded Vol.11.913m3 The manhole is located adjacent to permeable paving and as

such a large quantity of flood water will be retained within the

permeable paving. Dropped kerbs and overland flow paths will

direct the remaining flood water to landscaped areas and away

from buildings. The FFL of the nearest building is 53.10 and as

such is not at risk of flooding.

2 S15 49.28 Flooded Vol.103.663m3 The manhole is located adjacent to permeable paving and a

swale. As such a large quantity of flood water will be retained

within these suds features. Dropped kerbs and overland flow

paths will direct the remaining flood water to landscaped areas

and away from buildings. The FFL of the nearest building is 53.10

and as such is not at risk of flooding.

3 S10 49.40 49.218 Flood Risk – The pipe is surcharged to a level 182mm below the

cover level of the manhole. The manhole is situated close to a

swale which offers significant storage capacity in the case of

exceedance. The FFL of the nearest building is 53.10 and as such

is not at risk of flooding.

4 S7 49.15 Flooded Vol. 40.611m3 The manhole is located adjacent to permeable paving and as

such a large quantity of flood water will be retained within the

permeable paving. Dropped kerbs and overland flow paths will

direct the remaining flood water to landscaped areas and away

from buildings. The FFL of the nearest building is 53.10 and as

such is not at risk of flooding.


cover level of the manhole. The manhole contains a hydrobrake

which acts to maintain runoff to below greenfield levels as such

utilising the attenuation storage provided. The FFL of the nearest

building is 50.00 and as such is not at risk of flooding.


cover level of the manhole. The manhole is downstream of the

hydrobrake which acts to maintain runoff to below greenfield

levels as such utilising the attenuation storage provided. The FFL

of the nearest building is 50.00 and as such is not at risk of

flooding.

DBFL Consulting Engineers Page 1Ormond House CHURCHVIEW ROADUpper Ormond Quay 180153Dublin 7Date 31/05/2019 13:56 Designed by LMLFile 180153- Network- 50% Bl... Checked by SVCInnovyze Network 2018.1.1



Simulation CriteriaAreal Reduction Factor 1.000 Additional Flow - % of Total Flow 0.000

Hot Start (mins) 0 MADD Factor * 10m³/ha Storage 0.000Hot Start Level (mm) 0 Inlet Coeffiecient 0.800

Manhole Headloss Coeff (Global) 0.500 Flow per Person per Day (l/per/day) 0.000Foul Sewage per hectare (l/s) 0.000


Synthetic Rainfall DetailsRainfall Model FSR Ratio R 0.280

Region Scotland and Ireland Cv (Summer) 0.750M5-60 (mm) 15.700 Cv (Winter) 0.840

Margin for Flood Risk Warning (mm) 300.0Analysis Timestep 2.5 Second Increment (Extended)

DTS Status ONDVD Status OFF

Inertia Status OFF

Profile(s) Summer and WinterDuration(s) (mins) 15, 30, 60, 120, 180, 240, 360, 480, 600,

720, 960, 1440, 2160, 2880, 4320, 5760,7200, 8640, 10080

Return Period(s) (years) 100Climate Change (%) 10

PNUS/MHName Storm

ReturnPeriod

ClimateChange

First (X)Surcharge

First (Y)Flood

First (Z)Overflow

S1.000 S17 30 Winter 100 +10% 100/15 Summer 100/15 SummerS1.001 S16 15 Winter 100 +10% 100/15 SummerS1.002 S15 1440 Winter 100 +10% 100/15 Summer 100/15 SummerS1.003 S14 1440 Winter 100 +10% 100/15 SummerS1.004 S13 1440 Winter 100 +10% 100/15 SummerS2.000 S13.1 1440 Winter 100 +10% 100/15 SummerS1.005 Northern Attn. 1440 Winter 100 +10% 100/15 WinterS1.006 S12 1440 Winter 100 +10% 100/15 SummerS1.007 S11 960 Winter 100 +10% 100/15 SummerS1.008 S10 960 Winter 100 +10% 100/15 SummerS1.009 S9 960 Winter 100 +10% 100/15 SummerS1.010 S8 960 Winter 100 +10% 100/15 SummerS1.011 S7 960 Winter 100 +10% 100/15 Summer 100/120 WinterS3.000 S7.1 240 Winter 100 +10% 100/15 SummerS1.012 Southern Attn. 960 Winter 100 +10% 100/15 SummerS1.013 S6 240 Winter 100 +10% 100/15 SummerS1.014 S5 240 Winter 100 +10% 100/15 SummerS1.015 S4 240 Winter 100 +10% 100/15 Summer




PNUS/MHName

OverflowAct.

Water Level(m)

SurchargedDepth(m)

FloodedVolume(m³)

Flow /Cap.

Overflow(l/s)

PipeFlow(l/s) Status

S1.000 S17 49.663 1.118 13.043 2.01 27.7 FLOODS1.001 S16 49.763 1.283 0.000 1.52 30.9 FLOOD RISKS1.002 S15 49.315 1.114 35.263 0.42 5.4 FLOODS1.003 S14 49.313 1.160 0.000 0.40 5.3 SURCHARGEDS1.004 S13 49.311 1.178 0.000 0.24 7.8 SURCHARGEDS2.000 S13.1 49.310 1.285 0.000 0.16 2.4 SURCHARGEDS1.005 Northern Attn. 49.309 1.289 0.000 0.07 1.9 SURCHARGEDS1.006 S12 49.305 1.450 0.000 0.15 1.9 SURCHARGEDS1.007 S11 49.218 1.453 0.000 0.16 2.0 SURCHARGEDS1.008 S10 49.215 1.497 0.000 0.21 2.8 FLOOD RISKS1.009 S9 49.204 1.696 0.000 0.27 3.5 SURCHARGEDS1.010 S8 49.196 1.785 0.000 0.30 3.4 SURCHARGEDS1.011 S7 49.193 1.735 43.122 0.29 7.5 FLOODS3.000 S7.1 49.219 1.144 0.000 0.87 11.7 SURCHARGEDS1.012 Southern Attn. 49.192 1.794 0.000 0.21 5.5 SURCHARGEDS1.013 S6 49.203 1.865 0.000 0.24 5.8 SURCHARGEDS1.014 S5 49.213 1.921 0.000 0.21 5.3 SURCHARGEDS1.015 S4 49.208 2.016 0.000 0.10 4.0 FLOOD RISK

PNUS/MHName

LevelExceeded

S1.000 S17 7S1.001 S16S1.002 S15 12S1.003 S14S1.004 S13S2.000 S13.1S1.005 Northern Attn.S1.006 S12S1.007 S11S1.008 S10S1.009 S9S1.010 S8S1.011 S7 18S3.000 S7.1S1.012 Southern Attn.S1.013 S6S1.014 S5S1.015 S4




PNUS/MHName Storm

ReturnPeriod

ClimateChange

First (X)Surcharge

First (Y)Flood

First (Z)Overflow

OverflowAct.

Water Level(m)

S1.016 S3 240 Winter 100 +10% 46.821S1.017 S2 360 Winter 100 +10% 46.759S1.018 S1 360 Winter 100 +10% 46.457

PNUS/MHName

SurchargedDepth(m)

FloodedVolume(m³)

Flow /Cap.

Overflow(l/s)

PipeFlow(l/s) Status

LevelExceeded

S1.016 S3 -0.134 0.000 0.34 4.0 OKS1.017 S2 -0.152 0.000 0.23 4.0 OKS1.018 S1 -0.139 0.000 0.31 4.0 OK




192221-PR0 B-I June 2019

Appendix B Site Layout with Stage 1 Audit Findings Highlighted

KOKelly

Text Box

KOKelly

Call-out

2.1.6 Attenuation Storage Tanks & 2.1.3 Ponds

KOKelly

Call-out

2.1.6 Attenuation Storage Tanks

KOKelly

Call-out

2.1.10 Typical Swale Details - Permeable Liner

KOKelly

Call-out

2.2.1 Green Roofs & 2.2.2 Rainwater Harvesting

KOKelly

Call-out

2.2.1 Green Roofs

KOKelly

Call-out

2.2.1 Green Roofs

KOKelly

Call-out

2.1.5 Bypass Interceptor

KOKelly

Call-out

2.1.14 Hydrobrake

KOKelly

Call-out


KOKelly

Call-out


KOKelly

Call-out


KOKelly

Arrow

KOKelly

Call-out


KOKelly

Call-out


KOKelly

Call-out

2.1.12 Existing Natural Features on Site

KOKelly

Arrow

KOKelly

Call-out

2.1.4 Roads Surfacing/Porous Asphalt

KOKelly

Call-out

2.1.4 Roads Surfacing/Porous Asphalt

KOKelly

Arrow

KOKelly

Call-out

2.1.1 Filter Drains/ Bio-Retention




192221-PR0 C-I June 2019

Appendix C Storm Water Audit Feedback Form

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