Cahir Town Centre Car Park Engineering Design Report

Cahir Town Centre Car Park

Engineering Design Report Planning Stage

www.tobin.ie

Cahir Town Centre Car Park

Engineering Design Report

Document Control Sheet

Document Reference TR02 - Engineering Design Report

Report Status Planning

Report Date August 2021

Current Revision P0

Client: Tipperary County Council

Client Address: Tipperary County Council Civic Offices

Emmet Street,

Clonmel

Co. Tipperary

Project Number 11170

Galway Office Fairgreen House, Fairgreen Road, Galway, H91 AXK8, Ireland. Tel: +353 (0)91 565 211

Dublin Office Block 10-4, Blanchardstown Corporate Park, Dublin 15, D15 X98N, Ireland. Tel: +353 (0)1 803 0406

Castlebar Office Market Square, Castlebar, Mayo, F23 Y427, Ireland. Tel: +353 (0)94 902 1401

Revision Description Author: Date Reviewed

By: Date

Authorised by:

Date

D01 Draft Issue DM 26/08/2021 MG 26/08/2021 TM 26/08/2021 D02 Draft Issue DM 14/09/2021 MG 14/09/2021 TM 14/09/2021 D03 Draft Issue DM 22/09/2021 MG 22/09/2021 TM 22/09/2021 P0 Planning Issue DM 27/09/2021 MG 27/09/2021 TM 27/09/2021

TOBIN Consulting Engineers

Disclaimer This Document is Copyright of TOBIN Consulting Engineers Limited. This document and its contents have been prepared for the sole use of our Client. No liability is accepted by TOBIN Consulting Engineers Limited for the use of this report, or its contents for any other use than for which it was prepared.

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Table of Contents

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

1.1 GENERAL ......................................................................................................................... 1

1.2 ENGINEERING INFORMATION .............................................................................. 3

2.0 SURFACE WATER DRAINAGE OVERVIEW ............................................. 5

2.1 EXISTING STORM DRAINAGE ................................................................................ 5

2.2 PROPOSED STORM DRAINAGE ............................................................................ 6

2.3 SUSTAINABLE URBAN DRAINAGE SYSTEMS ................................................... 6

2.3.1 Attenuation Storage ..................................................................................................... 7

Table of Figures

Figure 1-1: Site Location Outlined in Red ............................................................. 1

Figure 1-2 Proposed Car Park Development ....................................................... 3

Appendices

Appendix 1 – Drawing Register

Appendix 2 – Storm Sewer Micro Drainage and Long sections

Appendix 3 – Runoff Volume Calculation (100-year 6-hour event)

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1.0 INTRODUCTION

1.1 GENERAL

TOBIN Consulting Engineers were appointed by Tipperary County Council in July 2021 to provide engineering consultancy services for a proposed car park development at Cahir, Co. Tipperary (See Figure 1.1 for site extents). TOBIN have been appointed to provide civil and traffic engineering design services for the planning stage of the project. This report was prepared to accompany a planning application by Tipperary County Council for the proposed development and it deals specifically with the surface water drainage, flood risk assessment and traffic engineering for this application.

Figure 1-1: Site Location Outlined in Red

The proposed development at the subject site (see Figure 1-2) will consist of, but not be limited to, the following works:

I. The demolition of an existing structure (the former Castle Court Hotel), associated outbuildings and boundary walls.

II. Demolition and reconfiguration works to outbuildings to the rear of the Market House Building (Protected Structure S241).

III. The construction of a new carpark, access road and junction onto Church Street including all site accommodation works. Vehicular and pedestrian access is to be provided off Church Street with a provision provided for an additional future pedestrian link through the adjacent Market House Building site onto Old Church Street.

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IV. The carpark will comprise of 91 spaces in total including 86 no. car parking spaces (including 3 no. disabled spaces and 4 no. Electric parking spaces), 3 no. standard bus and 2 no. minibus parking spaces and bicycle parking facilities.

V. The provision of 2 no. twin electric charging points to accommodate 4 no. electric car charging spaces onsite.

VI. All ancillary site works including retaining walls, bicycle parking, public lighting, bollards, landscaping, surface water drainage, connections to public services, signage, etc.

VII. The provision of electric parking capacity signage at the main entrance to the carpark.

VIII. Alterations to Church Street, including the provision of a raised table section of carriageway, provision of paved pedestrian areas and the relocation / removal of street furniture, road markings and street parking and all associated siteworks.

The proposed development is located within Cahir Town Architectural Conservation Area and is located adjacent to Protected Structure No. S241 and S246.

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Figure 1-2 Proposed Car Park Development

1.2 ENGINEERING INFORMATION

As part of the planning submission for the above development, TOBIN Consulting Engineers have prepared this Engineering Design Report to address the following design aspects of the proposed development

➢ Storm Water Drainage ➢ Flood Risk ➢ Junction Design and Internal Road Layout ➢ Traffic Engineering

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o Traffic and Transport Assessment (incl. Stage 1/2 Road Safety Audit)

The following drawings are included outlining the design proposals and a Drawing Register is

included in Appendix 1:

➢ 11170-2000 – Site Location Map ➢ 11170-2001 – Existing Site Layout ➢ 11170-2002 – Demolition Site Plan ➢ 11170-2003 – Proposed Site Layout ➢ 11170-2004 – Ex & Proposed Site Sections Sheet 1 ➢ 11170-2005 – Ex & Proposed Site Sections Sheet 2 ➢ 11170-2006 – Ex & Proposed Site Sections Sheet 3 ➢ 11170-2007 – Proposed Site Boundary Elevations Sheet 1 ➢ 11170-2008 – Proposed Site Boundary Elevations Sheet 2 ➢ 11170-2009 – Swept Path Analysis Sheet 1 ➢ 11170-2010 – Swept Path Analysis Sheet 2 ➢ 11170-2011 – Proposed Storm Drainage Layout ➢ 11170-2012 – Site Development Details Sheet 1 ➢ 11170-2013 – Site Development Details Sheet 2 ➢ 11170-2014 – Standard Manhole Details Sheet 1 of 2 ➢ 11170-2015 – Standard Manhole Details Sheet 2 of 2 ➢ 11170-2016 – Standard Pipe Bedding Details ➢ 11170-2017 – Market Building External Works ➢ 21.2177 PL – E001 Public Lighting Site Layout ➢ 1829-P8- Prop Link to Carpark ➢ 21690-1-101-LMP - Landscape Plan

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2.0 SURFACE WATER DRAINAGE OVERVIEW

The storm water drainage design has been designed to cater for all surface water runoff from all hard surfaces in the proposed development including roadways, roofs, paved areas etc. The storm water drainage services have been designed to take account of the requirements of the Department of Environment “Recommendations for Site Development Works for Housing Areas”, 1998, the “Greater Dublin Strategic Study” and “Sewers for Adoption” published by WRC, UK.

To comply with the principles of Sustainable Urban Drainage Systems it is proposed to incorporate attenuation systems into the surface water drainage design which will assist in minimising the impact of urbanisation by replicating the runoff characteristics of the greenfield site.

All stormwater generated on site from roadways and parking areas will discharge via Oil/Petrol Interceptor to the public sewer. Two offline attenuation areas will provide storage capacity in high intensity rainfall events. Discharge flow will be controlled by a hydrobrake flow control device which will limit flow from the site so as not to exacerbate any capacity issues within the downstream network. Both attenuation areas are designed to accommodate a 1 in 100-year storm event throughout the site.

The proposed petrol interceptor will be Class 1 Bypass type and will be installed upstream of the connection into the existing public surface water sewer. This is required as the storm water entering the system will include run-off from the roadways and parking areas throughout the site and therefore may have hydrocarbons within the flow. These hydrocarbon pollutants require removal and are not to be discharged back into the environment.

The storm drainage for the entire development has been designed using the Innovyze MicroDrainage Design Software in accordance with the Recommendations for Site Development Works for Housing Areas and the Greater Dublin Strategic Drainage Study (GDSDS).

2.1 EXISTING STORM DRAINAGE

From survey data, onsite inspections and our review of other available records, we have identified the following surface water drainage networks within the vicinity of the site.

• Existing onsite: There are a number of internal storm water networks located within the existing site resulting from existing buildings, however there is no clear outfall point to the public sewer network.

• Western Boundary: Church Street runs adjacent to the site at this location. Beneath this road is a ø225mm clay pipe foul sewer and a ø375mm concrete combined sewer. The ø225mm foul sewer discharges to the ø375mm combined sewer which continues west and then south to connect to the Cahir WTTP.

Please refer to Drawing Ref. 11170-2011 which outline the details of the existing storm sewer network.

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2.2 PROPOSED STORM DRAINAGE

The storm water drainage network was designed using Innovyze MicroDrainage Design software and the following parameters formed the basis of the design:

- The surface water run-off is calculated using the Modified Rational Method (Wallingford Procedure),

Q = 2.78 x Cv x Cr x I x A

Where, Q = rate of run-off, l/s

Cv = Volumetric run-off coefficient

Cr = Routing coefficient

I = Intensity of rainfall, mm/hr

A = Impermeable Area, ha

- A design return period of 1 year has been adopted for the sewer network in accordance with good design practice.

- The rainfall intensity is based on rainfall data for County Tipperary - Minimum self-cleansing velocity of 0.75m/s - An allowable discharge of 2l/s/ha for the site - M5-60 = 20 - Ratio (R) = 0.3

A dedicated storm water drainage system will be provided for the development and will pick up surface water run-off from roadways, footways, pedestrianised zones and car parking areas, this water will be directed through a petrol interceptor before discharging to the public sewer network. One offline attenuation tank will be installed to provide storage capacity.

Surface water runoff from roads and footpaths throughout the site will be collected by a combination of channel drains and precast concrete gullies with lockable cast iron grating and frame connected to a piped system.

All sewers have been designed so that the velocities achieved fall within the limits of 0.8 and 3m/sec as set out in ‘Recommendations for Site Development Works’ as published by the Department for the Environment.

Refer to Drawing 11170-2011 which outlines the details of the proposed storm sewer network. Refer to Appendix 3 for storm sewer calculations.

2.3 SUSTAINABLE URBAN DRAINAGE SYSTEMS

The existing site is part greenfield part brownfield with no existing drainage or SuDS measures in place. In order to maintain surface water runoff from the site close to that of the current state and to diminish the additional hydraulic load downstream, the surface water drainage for the proposed development will be designed in accordance with the principles of Sustainable Urban Drainage Systems (SuDS) as embodied in the recommendations of the Greater Dublin Strategic Drainage Study (GDSDS). The GDSDS addresses the issue of sustainability by requiring designs to comply with a set of drainage criteria which aim to minimise the impact of urbanisation by replicating the runoff characteristics of the greenfield site.

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The requirements of SuDS are typically addressed by the provision of one or more of the following:

➢ Interception storage ➢ Treatment storage ➢ Attenuation storage ➢ Long term storage (if this is not required growth rates should not be applied to QBar)

In the case of the subject site attenuation storage can be achieved by 1 No. attenuation storage tank. Growth factors will not be applied to the allowable discharge for the 100 year event. This means that both treatment storage and long term storage (neither of which would be practical on this site) are not required. All SuDS measures will be designed in accordance with the recommendation set out in the EPA’s document entitled “Guidance on Authorisation of Discharges to Groundwater 2011”

2.3.1 Attenuation Storage

One attenuation tank will be used on site to provide storage. The tank will be formed by StormTech dome shaped chambers or similar product. Discharge flow will be controlled by a hydrobrake flow control device which will limit flow from the site to greenfield rates or lower. The greenfield run-off rate for the site is calculated using the IH124 method.

Calculation of QBAR:

QBAR = 0.00108 x (AREA)0.89 x SAAR1.17 x SOIL2.17

Where:

• QBAR = m3/s • AREA = km2 = 0.5 • SAAR = mm = 1079 for Cahir • SOIL = soil index = 0.629 - taken from the FSU Web Portal for Location

Where the site is less than 50ha, QBAR for is calculated for 50 ha and then linear interpolation is used for smaller areas:

QBAR = 0.00108 x (0.5)0.89 x 10791.17 x 0.62.17 = 0.754 m3/s

• The total impermeable area for the proposed parking area is 3,566m2, therefore for an area of 0.36ha; QBAR = (754/50) x 0.36 = 5.38 l/s Based on the above parameters the maximum allowable outflow is therefore 5.38l/s from the attenuation tank for the development however it is considered that this discharge rate is excessively high as the Soil Index obtained from the FSU web portal for Cahir does not accurately reflect the site characteristics. Using the HR Wallingford approach the Soil Index has been reduced to 0.3 reducing the Greenfield Run-off Rate to 2.1 l/s. To accommodate the discharge rate the required storage volume for the development has been calculated to be 170m3 as per the calculations included in Appendix 3. To

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provide this storage capacity, a Stormtech or similar approved systems totalling 228.2m3 storage capacity is proposed.

The attenuation storage volumes are sized for a 100-year storm plus 10% to allow for climate change in accordance with the GDSDS.

Appendix 1 – Drawing Register

3Issue No:Date: 30 Sep 2021Issued By: Micheal Geraghty

Copy For Frank CussenIssue Notes:

DrawingsTitle Revision Issue ReasonDrawing No. RenditionsSite Location Map P0 For Information11170-2000 pdfEx Site Layout P0 For Information11170-2001 pdfDemolition Layout P0 For Information11170-2002 pdfProposed Site Layout P0 For Information11170-2003 pdfSignage & Linemarking P0 For Information11170-2004 pdfExisting & Proposed Site Section Sheet 1 of 2 P0 For Information11170-2005 pdfExisting & Proposed Site Section Sheet 2 of 2 P0 For Information11170-2006 pdfExisting and Proposed Elevations Sheet 1 of 2 P0 For Information11170-2007 pdfExisting and Proposed Elevations Sheet 2 of 2 P0 For Information11170-2008 pdfSwept Path Analysis Sht 1 P0 For Information11170-2009 pdfSwept Path Analysis Sht 2 P0 For Information11170-2010 pdfProposed Storm Drainage Layout P0 For Information11170-2011 pdfSite Development Details Sheet 1 of 2 P0 For Information11170-2012 pdfSite Development Details Sheet 2 of 2 P0 For Information11170-2013 pdfStandard Manhole Details Sheet 1 of 2 P0 For Information11170-2014 pdfStandard Manhole Details Sheet 2 of 2 P0 For Information11170-2015 pdfStandard Pipe Bedding Details P0 For Information11170-2016 pdfMarket House Building Proposed External Works P0 For Information11170-2017 pdfLANDSCAPE RevA P0 For Information1829-SK-105 pdfPublic Lighting-A1 P0 For Information21.2177 PL-E001 pdf21-09-25-ISSUED P0 For Information21690-1-101-LMP pdf

RecipientsRecipient Name Role Media CopiesFrank Cussen (Tipperary County Council Clonmel) Client 11Hardcopy

Document Issue Sheet

11170 Tipperary Co Co Provision of Consultancy Designand Management Services for the provision of a CarPark in Cahir Town Centre

TOBIN Consulting Engineers Fairgreen House, Fairgreen Road, Galway, Ireland H91AXK8 Tel: +353 (0)91 565211 Fax: +353 (0)91 565398 Web: www.tobin.ie

Page 1 | 1

Appendix 2 – Storm Sewer Micro Drainage and Long sections

Model & Results

Long sections

TOBIN Consulting Engineers Page 1Fairgreen House 11170 - Cahir Car ParkFairgreen RoadGalwayDate 09/09/2021 17:10 Designed by SBFile 11170 - Cahir Car Park Microdrainage.MDX Checked by DMMicro Drainage 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) 1 Foul Sewage (l/s/ha) 0.000 Maximum Backdrop Height (m) 1.500

M5-60 (mm) 17.800 Volumetric Runoff Coeff. 0.850 Min Design Depth for Optimisation (m) 1.200Ratio R 0.273 PIMP (%) 100 Min Vel for Auto Design only (m/s) 0.75

Maximum Rainfall (mm/hr) 55 Add Flow / Climate Change (%) 0 Min Slope for Optimisation (1:X) 250Maximum Time of Concentration (mins) 30 Minimum Backdrop Height (m) 0.200

Designed with Level Soffits

Network Design Table for Storm

« - Indicates pipe capacity < flow

PN Length(m)

Fall(m)

Slope(1:X)

I.Area(ha)

T.E.(mins)

BaseFlow (l/s)

k(mm)

HYDSECT

DIA(mm)

Section Type AutoDesign

Network Results Table

PN Rain(mm/hr)

T.C.(mins)

US/IL(m)

Σ I.Area(ha)

Σ BaseFlow (l/s)

Foul(l/s)

Add Flow(l/s)

Vel(m/s)

Cap(l/s)

Flow(l/s)




PN Length(m)

Fall(m)

Slope(1:X)

I.Area(ha)

T.E.(mins)

BaseFlow (l/s)

k(mm)

HYDSECT

DIA(mm)


1.000 14.200 0.142 100.0 0.057 5.00 0.0 0.600 o 150 Pipe/Conduit

2.000 44.500 0.890 50.0 0.182 5.00 0.0 0.600 o 225 Pipe/Conduit2.001 4.900 0.025 200.0 0.000 0.00 0.0 0.600 o 225 Pipe/Conduit

1.001 22.100 0.221 100.0 0.031 0.00 0.0 0.600 o 225 Pipe/Conduit



PN Rain(mm/hr)

T.C.(mins)

US/IL(m)

Σ I.Area(ha)

Σ BaseFlow (l/s)

Foul(l/s)

Add Flow(l/s)

Vel(m/s)

Cap(l/s)

Flow(l/s)

1.000 42.90 5.24 47.600 0.057 0.0 0.0 0.0 1.00 17.8 7.5

2.000 42.41 5.40 48.360 0.182 0.0 0.0 0.0 1.85 73.7 23.72.001 42.16 5.49 47.470 0.182 0.0 0.0 0.0 0.92 36.6 23.7

1.001 41.37 5.77 47.383 0.270 0.0 0.0 0.0 1.31 52.0 34.3

3.000 42.79 5.27 45.570 0.027 0.0 0.0 0.0 1.07 42.4 3.53.001 42.26 5.45 45.454 0.071 0.0 0.0 0.0 0.93 36.8 9.2




PN Length(m)

Fall(m)

Slope(1:X)

I.Area(ha)

T.E.(mins)

BaseFlow (l/s)

k(mm)

HYDSECT

DIA(mm)


1.002 10.700 0.082 130.2 0.016 0.00 0.0 0.600 o 225 Pipe/Conduit




PN Rain(mm/hr)

T.C.(mins)

US/IL(m)

Σ I.Area(ha)

Σ BaseFlow (l/s)

Foul(l/s)

Add Flow(l/s)

Vel(m/s)

Cap(l/s)

Flow(l/s)

1.002 40.95 5.93 45.403 0.357 0.0 0.0 0.0 1.14 45.5 44.9

4.000 41.64 5.67 45.570 0.000 0.0 0.0 0.0 0.92 36.6 0.04.001 41.02 5.90 45.384 0.000 0.0 0.0 0.0 0.92 36.6 0.0

1.003 40.44 6.12 45.321 0.357 0.0 0.0 0.0 1.07 42.4« 44.91.004 39.74 6.40 45.062 0.357 0.0 0.0 0.0 1.28 90.6 44.9


Manhole Schedules for Storm


MHName

MHCL (m)

MHDepth(m)

MHConnection

MHDiam.,L*W

(mm)PN

Pipe OutInvert

Level (m)Diameter(mm)

PNPipes InInvert

Level (m)Diameter(mm)

Backdrop(mm)

Pr S01 48.950 1.350 Open Manhole 1200 1.000 47.600 150

Pr S07 50.380 2.020 Open Manhole 1200 2.000 48.360 225

Pr S08 48.790 1.320 Open Manhole 1200 2.001 47.470 225 2.000 47.470 225

Pr S02 48.480 1.097 Open Manhole 1200 1.001 47.383 225 1.000 47.458 150

2.001 47.446 225 63

Pr S11 46.720 1.150 Open Manhole 1200 3.000 45.570 225

Pr S12 47.630 2.176 Open Manhole 1200 3.001 45.454 225 3.000 45.454 225

Pr S03 48.430 3.027 Open Manhole 1200 1.002 45.403 225 1.001 47.162 225 1759

3.001 45.403 225

Attenuation 48.950 3.380 Open Manhole 1200 4.000 45.570 225

Pr S13 47.960 2.576 Open Manhole 1200 4.001 45.384 225 4.000 45.384 225

Pr S04 46.840 1.519 Open Manhole 1200 1.003 45.321 225 1.002 45.321 225

4.001 45.321 225

Pr S05 46.570 1.508 Open Manhole 1200 1.004 45.062 300 1.003 45.237 225 100

Ex F01 46.310 1.392 Open Manhole 0 OUTFALL 1.004 44.918 300


PIPELINE SCHEDULES for Storm

Upstream Manhole


PN HydSect

Diam(mm)

MHName

C.Level(m)

I.Level(m)

D.Depth(m)

MHConnection

MH DIAM., L*W(mm)

1.000 o 150 Pr S01 48.950 47.600 1.200 Open Manhole 1200

2.000 o 225 Pr S07 50.380 48.360 1.795 Open Manhole 12002.001 o 225 Pr S08 48.790 47.470 1.095 Open Manhole 1200



Downstream Manhole

PN Length(m)

Slope(1:X)

MHName

C.Level(m)

I.Level(m)

D.Depth(m)

MHConnection

MH DIAM., L*W(mm)

1.000 14.200 100.0 Pr S02 48.480 47.458 0.872 Open Manhole 1200

2.000 44.500 50.0 Pr S08 48.790 47.470 1.095 Open Manhole 12002.001 4.900 200.0 Pr S02 48.480 47.446 0.810 Open Manhole 1200

1.001 22.100 100.0 Pr S03 48.430 47.162 1.043 Open Manhole 1200



PIPELINE SCHEDULES for Storm

Upstream Manhole


PN HydSect

Diam(mm)

MHName

C.Level(m)

I.Level(m)

D.Depth(m)

MHConnection

MH DIAM., L*W(mm)


4.000 o 225 Attenuation 48.950 45.570 3.155 Open Manhole 12004.001 o 225 Pr S13 47.960 45.384 2.351 Open Manhole 1200


Downstream Manhole

PN Length(m)

Slope(1:X)

MHName

C.Level(m)

I.Level(m)

D.Depth(m)

MHConnection

MH DIAM., L*W(mm)

1.002 10.700 130.2 Pr S04 46.840 45.321 1.294 Open Manhole 1200


1.003 12.600 150.0 Pr S05 46.570 45.237 1.108 Open Manhole 12001.004 21.600 150.0 Ex F01 46.310 44.918 1.092 Open Manhole 0


Area Summary for Storm


PipeNumber

PIMPType

PIMPName

PIMP(%)

GrossArea (ha)

Imp.Area (ha)

Pipe Total(ha)

1.000 - - 100 0.057 0.057 0.0572.000 - - 100 0.182 0.182 0.1822.001 - - 100 0.000 0.000 0.0001.001 - - 100 0.031 0.031 0.0313.000 - - 100 0.027 0.027 0.0273.001 - - 100 0.044 0.044 0.0441.002 - - 100 0.016 0.016 0.0164.000 - - 100 0.000 0.000 0.0004.001 - - 100 0.000 0.000 0.0001.003 - - 100 0.000 0.000 0.0001.004 - - 100 0.000 0.000 0.000

Total Total Total0.357 0.357 0.357

Free Flowing Outfall Details for Storm

OutfallPipe Number

OutfallName

C. Level(m)

I. Level(m)

MinI. Level

(m)

D,L(mm)

W(mm)

1.004 Ex F01 46.310 44.918 0.000 0 0


Online Controls for Storm


Hydro-Brake® Optimum Manhole: Pr S04, DS/PN: 1.003, Volume (m³): 2.6

Unit Reference MD-SHE-0064-2000-1200-2000 Sump Available YesDesign Head (m) 1.200 Diameter (mm) 64

Design Flow (l/s) 2.0 Invert Level (m) 45.321Flush-Flo™ Calculated Minimum Outlet Pipe Diameter (mm) 100Objective Minimise upstream storage Suggested Manhole Diameter (mm) 1200

Application Surface

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

Design Point (Calculated) 1.200 2.0 Kick-Flo® 0.573 1.4Flush-Flo™ 0.282 1.8 Mean Flow over Head Range - 1.6

The hydrological calculations have been based on the Head/Discharge relationship for the Hydro-Brake® Optimum as specified. Shouldanother type of control device other than a Hydro-Brake Optimum® be utilised then these storage routing calculations will be invalidated

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

0.100 1.5 0.600 1.5 1.600 2.3 2.600 2.8 5.000 3.9 7.500 4.70.200 1.7 0.800 1.7 1.800 2.4 3.000 3.0 5.500 4.0 8.000 4.80.300 1.8 1.000 1.8 2.000 2.5 3.500 3.3 6.000 4.2 8.500 5.00.400 1.7 1.200 2.0 2.200 2.6 4.000 3.5 6.500 4.4 9.000 5.10.500 1.6 1.400 2.1 2.400 2.7 4.500 3.7 7.000 4.5 9.500 5.2


Storage Structures for Storm


Cellular Storage Manhole: Pr S04, DS/PN: 1.003

Invert Level (m) 45.321 Infiltration Coefficient Side (m/hr) 0.00000 Porosity 0.95Infiltration Coefficient Base (m/hr) 0.00000 Safety Factor 2.0

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

0.000 200.0 200.0 1.100 200.0 272.6 1.200 0.0 272.6


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


Simulation CriteriaAreal Reduction Factor 1.000 Manhole Headloss Coeff (Global) 0.500 MADD Factor * 10m³/ha Storage 2.000

Hot Start (mins) 0 Foul Sewage per hectare (l/s) 0.000 Inlet Coeffiecient 0.800Hot Start Level (mm) 0 Additional Flow - % of Total Flow 0.000 Flow per Person per Day (l/per/day) 0.000

Number of Input Hydrographs 0 Number of Offline Controls 0 Number of Time/Area Diagrams 0Number of Online Controls 1 Number of Storage Structures 1 Number of Real Time Controls 0

Synthetic Rainfall DetailsRainfall Model FSR M5-60 (mm) 17.800 Cv (Summer) 0.750

Region Scotland and Ireland Ratio R 0.273 Cv (Winter) 0.840

Margin for Flood Risk Warning (mm) 300.0 DTS Status ON Inertia Status OFFAnalysis Timestep Fine DVD Status OFF

Profile(s) Summer and WinterDuration(s) (mins) 15, 30, 60, 120, 240, 360, 480, 720, 1440, 2880

Return Period(s) (years) 30, 100Climate Change (%) 10, 20

PNUS/MHName Storm

ReturnPeriod

ClimateChange

First (X)Surcharge

First (Y)Flood

First (Z)Overflow

OverflowAct.

Water Level(m)

SurchargedDepth(m)

FloodedVolume(m³)

Flow /Cap.

Overflow(l/s)

PipeFlow(l/s)

1.000 Pr S01 15 Winter 100 +20% 30/15 Summer 48.377 0.627 0.000 1.19 19.42.000 Pr S07 15 Winter 100 +20% 100/15 Summer 49.148 0.563 0.000 0.92 65.02.001 Pr S08 15 Winter 100 +20% 30/15 Summer 48.392 0.697 0.000 2.41 64.0




PNUS/MHName Status

LevelExceeded

1.000 Pr S01 SURCHARGED2.000 Pr S07 SURCHARGED2.001 Pr S08 SURCHARGED




PNUS/MHName Storm

ReturnPeriod

ClimateChange

First (X)Surcharge

First (Y)Flood

First (Z)Overflow

OverflowAct.

Water Level(m)

SurchargedDepth(m)

FloodedVolume(m³)

Flow /Cap.

Overflow(l/s)

PipeFlow(l/s)

1.001 Pr S02 15 Winter 100 +20% 30/15 Summer 48.188 0.580 0.000 1.90 90.23.000 Pr S11 1440 Winter 100 +20% 30/15 Summer 46.379 0.584 0.000 0.02 0.73.001 Pr S12 1440 Winter 100 +20% 30/15 Summer 46.379 0.700 0.000 0.06 1.81.002 Pr S03 1440 Winter 100 +20% 30/15 Summer 46.379 0.751 0.000 0.25 9.54.000 Attenuation 1440 Winter 100 +20% 30/120 Winter 46.375 0.580 0.000 0.00 0.04.001 Pr S13 1440 Winter 100 +20% 30/30 Summer 46.376 0.766 0.000 0.00 0.11.003 Pr S04 1440 Winter 100 +20% 30/15 Winter 46.376 0.830 0.000 0.05 1.91.004 Pr S05 1440 Winter 100 +20% 45.093 -0.269 0.000 0.02 1.9

PNUS/MHName Status

LevelExceeded

1.001 Pr S02 FLOOD RISK3.000 Pr S11 SURCHARGED3.001 Pr S12 SURCHARGED1.002 Pr S03 SURCHARGED4.000 Attenuation SURCHARGED4.001 Pr S13 SURCHARGED1.003 Pr S04 SURCHARGED1.004 Pr S05 OK



Pr S01

1.000

150

100.0

48.950

47.600

47.458

14.200

Pr S02

1.001

225

100.0

48.480

47.383

47.162

22.100

Pr S03

1.002

225

130.2

48.430

45.403

45.321

10.700

Pr S04

1.003

225

150.0

46.840

45.321

45.237

12.600

Pr S05

1.004

300

150.0 46.570

45.062

44.918

21.600

Ex F01

46.310

MH Name

PN

Dia (mm)

Slope (1:X)

Cover Level (m)

Invert Level (m)

Length (m)

Datum (m)43.000

Ver Scale 100

Hor Scale 850

2.001

3.0014.001



Pr S07

2.000

225

50.0

50.380

48.360

47.470

44.500

48.790

47.470

Pr S02

48.480

MH Name

PN

Dia (mm)

Slope (1:X)

Cover Level (m)

Invert Level (m)

Length (m)

Datum (m)45.000

Ver Scale 100

Hor Scale 8501.000



Pr S11

3.000

225

150.0

46.720

45.570

45.454

17.400

47.630

45.454

45.403

Pr S03

48.430

MH Name

PN

Dia (mm)

Slope (1:X)

Cover Level (m)

Invert Level (m)

Length (m)

Datum (m)43.000

Ver Scale 100

Hor Scale 850

1.001



Attenuation

4.000

225

200.0

48.950

45.570

45.384

37.130

Pr S13

4.001

225

200.0

47.960

45.384

45.321

12.700

Pr S04

46.840

MH Name

PN

Dia (mm)

Slope (1:X)

Cover Level (m)

Invert Level (m)

Length (m)

Datum (m)44.000

Ver Scale 100

Hor Scale 850

1.002

Appendix 3 – Runoff Volume Calculation (100-year 6-hour event)

Calculation using FSU Figures

HR Wallingford Method

APPENDIX NO.11170 Cahir Town Car ParkCalculation of Surface Water Run-off from Development Catchments

GREENFIELD RUN-OFF TOTAL CATCHMENT DEVELOPABLE AREA 0.3566 ha

Calculation of Allowable Site Discharge (Grass Area Only)

QBARrural = 0.00108AREA0.89SAAR1.17SOIL2.17

Where:QBARrural is the mean annual flood flow from a rural catchment in m3/sAREA is the area of the catchment in km2SAAR is the standard average annual rainfallSOIL is a measure of the soil type derived from the FSR Winter Rainfall Acceptance Potential (WRAP) soil map

It is recommended thatthis formula should not be applied to areas less than 50ha. However, for developments smaller thanthis size, QBAR can be calculated fro 50ha, and flow rates for smaller areas can be linearly interpoloated.

Hence, calculation of QBAR for 50ha:AREA 0.5 km2SAAR 1079.54 mm FSUSOIL 0.6

QBARrural = 0.00108x(0.5^0.89)(1290^1.17)(0.3^2.17)

0.00108 0.539614 3,539.071 0.365655 AminPD0.754 m3/s

754.1683 l/s

Calculation of QBAR for: 0.36 ha (Green Area)AREA = 0.36 haQBARrural = 754.17 / 50 x 0.36

QBARrural = 5.38 l/s15.08 l/s/ha

The maximum discharge from the developed site will not exceed the pre-development run-off for a storm of one-year return period. To estimate the greenfield run-off for a small catchment - use the equation developed by the UK Institute of Hydrology in their Report 124 "Flood Estimation for Small Catchments", 1994.

DATE TOBIN Consulting Engineers

www.tobin.ie

TOBIN Consulting Engineers @tobinengineers

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Documents

Cahir Town Centre Car Park Engineering Design Report