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POTENTIAL OF ROAD SUBSURFACE

ON-SITE STORM WATER DETENTION SYSTEM

DARRIEN MAH YAU SENG

1i. 2.? 5201 ý

© Darrien Mah Yau Seng 2016

All rights reserved. No part of this publication may be reproduced, stored in retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior permission of the publisher.

Published in Malaysia by

UNIMAS Publisher, Universiti Malaysia Sarawak, 94300 Kota Samarahan, Sarawak, Malaysia.

Printed in Malaysia by

PPKS PRODUCTION SDN. BHD (673666-")

Jalan Canna, Off Jalan Wan Aiwi

Tabuan Jaya 93050

Kuching, Sarawak, Malaysia.

Perpustakaan Negara Malaysia Cataloguing-in-Publication Data

Mah, Darrien Yau Seng, 1977- POTENTIAL OF ROAD SUBSURFACE ON-SITE STORMWATER DETENTION SYSTEM / DARRIEN MAH YAU SENG Includes index Bibliography: pages 63 ISBN 976-967-2008-05-7 1. Flood control. 2. Pavements. 3. Urban runoff--Management. 1. Title 627.42

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PREFACE

This is the full report for UNIMAS Small Grant Scheme F02(S147)/1127/2014(12).

The idea of having a road subsurface detention system was first surfaced in 2012. A group of UNIMAS researchers had contributed to the methodology

of setting up such a system. It took a couple of years to see the idea grew to become an actual product. This technical report is the first, hopefully in

a series of reports on a product named StormPav. Here, the hydrological

aspects of road subsurface detention system are explored, investigated

and discussed. It presents the initial results spearheading the forming of

prototype for further studies.

The author would like to express gratitude to other team members who have been working hard for this project. It has been a delightful journey

to be able to involve in the birth of StormPav, and wishes are extended to have the product succeeded against the test of time for many years to

come.

Dr Darrien Mah

March 2016

VII

EXECUTIVE SUMMARY

Hydrology

No. Highlight Justification Page

1 Design rainfall of 3 DID Sarawak has a categorization of hours 10-year ARI is rainfall intensity, in which > 60 mm/h adopted for worst case is classified as Very Heavy or Red Alert

scenario. storm. 39

Intensity = 59.5 mm/h Depth = 178.4 mm

Prototype Design


1 Prototype has a top cover, Conventional road paving consists of a bottom plate and a layers of aggregate and top bitumen hollow cylinder as a single furnish up to 0.4 m. The different 34 unit of OSD. Total height is is small as not to cause too drastic

0.45 m. change in road laying practices. 2 Storage layer consists of It is recommended to have full

35 0.3 m in height with multi- detention of road-generated surface 42 unit hollow cylinders of runoff, because road catchments are 52 Inner diameter = 0.28 m relatively small, only 10% compared 53 Thickness of wall = 0.06 m to house catchments.

3 Top cover layer is also the The surface open area, consists of pavement layer, which is inlet hole and gap in between units, is 0.075 m thick. calculated as: 35 Hexagonal plate = 0.1624 Surface open area / pervious = 2% 43 mZ Concrete surface / impervious = 98% 44 Inlet hole = 0.04 m Permeability rate = 180 mm/hr per 45 diameter hole Perimeter = 1.5 m

ix

4 Bottom plate layer lays The focus is more emphasized on on native soil separated storage. As long as the capacity to 36 by a layer of geotextile. store stormwater is met, infiltration 42 Similar to top cover, every and slow release are then ensured plate has a hole of 0.04 m processes that follow. Therefore, both in diameter. Gap exists in are excluded at this stage. between units.

Study Area


1 Residential area in It is a representation of typical Lorong Keranji 4, Tabuan housing estate. 37 Jaya

2 Road width is 3m wide The road is local street classified as one way; 6m for two JKR Class U3 Urban road, with speed

37

ways. control below 60 km/h. 38

Storm Conveyance Model


1 SWMM version 5 is used. SWMM is the oldest computer 40 software for stormwater modelling.

2 MSMA is extensively MSMA is recognized as the official 69 referred. guideline for stormwater-related 70

design in Malaysia. 3 Disconnected System This model is used to demonstrate

model the distribution of surface runoffs 51

from different catchments in the 52 53

study area.

x

4 OSD Section model This model is specific to a section of road catchment.

Area =3mx1.3 m The road width complies with ]KR 54 (1% of 1-way lane) U3. 55

The length follows the design of rainfall simulator the researcher team Intended to fabricate.

It is modelled as This modelling technique Is found to 42 "pavement with storage". be the most workable in the context 43

of Road Subsurface OSD.

Modelling Results


1 OSD Section subjected Simulation of worst case scenario to 3 hours 10-year ARI Indicates a need of road kerb at least

design rainfall 100 mm high to contain the volume of stormwater and allow them to 57

permeate to storage chambers over time. Excessive surface ponding is predicted.

2 OSD Section subjected It is a light storm but spanned for to observed January 15 10 hours continuously. Intensity of

storm event rainfall was below 10 mm throughout 58 the event. Simulation of this event 59 shows the OSD functions adequately. No surface ponding is predicted.

3 O5D Section subjected It is a heavy storm for only 4 hours, to observed January 5 with high intensity at the beginning storm event and slowly weakening over the course

of storm. Simulation of this event 58 observes full capture of the rainfalls 59 that reinstating the OSD functions

adequately. Only slight surface ponding is predicted.

XI

Puset KhiÄmlt MAtnmivt AVa+-mft UNIVERSItI MAt. kvc. I+ cqRa u"K

Tables of Contents

Preface

Executive Summary

Table of Contents

List of Tables

List of Figures

CHAPTER 1 INTRODUCTION

1.1 Background 1.2 On-Site Detention System

1.3 Problem Statement

1.4 Hypothesis

1.5 Organization of Monograph

CHAPTER 2 LITERATURE REVIEW

2.1 Natural Hydrologic Cycle

2.2 Urban Hydrologic Cycle

2.3 Stormwater Management

2.4 Water Sensitive Urban Design

2.5 On-Site Detention

2.6 Urban Storm Water Management Manual for Malaysia

2.7 Design Criteria 2.8 Modelling of On-Site Detention 2.9 Case Studies of On-Site Detention

CHAPTER 3 METHODOLOGY

3.1 Proposed Design

3.2 Modelling Approach

3.3 Study Area

3.4 Design Rainfall

3.5 Surface Runoff

3.6 Detention Storage

3.7 Representation of On-Site Detention

vii

ix

xiii xv

xv

1

1

2

3

3

4

5

5

7

8

9

11

16

18

21

23

33

33

35

37

39

40

41

42

xiii

CHAPTER 4 RESULTS AND DISCUSSION 51

4.1 Rationale of Modelling Approach 51

4.2 Modelling of Road Surface On-site Detention 54

CHAPTER 5 CONCLUSIONS AND RECOMMENDATION 61

5.1 Conclusions 61

5.2 Recommendation 62

REFERENCES 63

APPENDIX A Design Rainfall for Kuching 69

APPENDIX B Computation of Runoff for Disconnected System 69

APPENDIX C SWMM-Computed Runoff 70

APPENDIX D References of PSD, SSR, Inlet, Outlet and Storage 70

Volume

APPENDIX E Observed Rainfall of January 2014 71

APPENDIX F Fl. Output of OSD Section subjected to January 15 Storm Event 71

F2. Output of OSD Section subjected to January 5 Storm Event

72

INDEX 73

XIV

LIST OF TABLES

2.1 Summary of SWMM Modelling Techniques and Measurement of Efficiency

3.1 Measurement of Study Area

3.2 Properties of JKR U3 Urban Road

3.3 Categorization of Rainfall Intensity (mm per hour) 3.4 Estimation of Surface Perviousness of OSD Section 3.5 Recommendations of Permeability for Permeable Pavement 3.6 Examples of Kerb Heights

3.7 Modelling Parameters of OSD Section 4.1 Amount of Computed Runoff 4.2 Estimation of Road Subsurface OSD Volume 4.3 Expected Outcomes for Verification of OSD Section 4.4 Output of OSD Section Modelling

LIST OF FIGURES

32

38

38

39

44

45

46

49

52

53

54

57

2.1 Hydrologic Cycle (www. exploringnature. org) 6 2.2 Scenarios of Hydrograph (Sidek et al., 2004; Zakaria et al., 2004) 10

2.3 Typical On-Site Detention Storage Facilities (DID, 2012) 12

2.4 Examples of Below-Ground Tank 13

2.5 Examples of Below-Ground Pipe Packages 14

2.6 Examples of Below-Ground Precast Concrete Block with Hollow 15 Chamber

2.7 Examples of Below-Ground Modular Block 16 2.8 Nonlinear Reservoir Representation of a Subcatchment (Huber

20 and Dickinson, 1988)

2.9 Inflow and Outflow Hydrographs for Detention Systems (PUB, 21 2010)

2.10 Conceptual of Drainage Modelling 23 2.11 Modelling of Detention Tank In Belo Horizonte (Drumond et al., 24

2013)

xv

2.12 Modelling of Detention Tank in Czestochowa City (Mrowlec and 26 Kisiel, 2008)

2.13 Modelling of Drainage System in Meakin Terrace (Pezzanitl, 27 2006)

2.14 Modelling of Mostacciano Experimental Catchment (Rianna et al., 29 2011)

2.15 Modelling of Drainage Area A of Metro West (LID Design Group, 30 2005)

2.16 Modelling of Easy Street (Dierks, 2009) 31

3.1 Comparing Conventional Paving and Road Subsurface OSD 34

3.2 Properties of Road Subsurface OSD 35

3.3 Concept of Stormwater Conveyance Model 36

3.4 Aerial of Lorong Keranji 4 (www. bing. com/maps/) 37

3.5 Rainfall-Runoff Simulation in SWMM (Huber and Dickinson, 1988) 40

3.6 Representation of Subcatchment in SWMM for Runoff Computation 41

3.7 Storage Layer 41

3.8 Top Cover-Cum-Pavement Layer 43

3.9 Experiment to Investigate Permeability Rate 47

4.1 Subcatchmentsin Study Area 51

4.2 OSD Section in Relative to Disconnected System Model 52

4.3 Input of Data for OSD Section 56

4.4 Modelling of OSD Section 57

4.5 Detention of 10-hour Observed Light Storm 59

4.6 Detention of 4-hour Observed Heavy Storm 59

xvi

CHAPTER 1

INTRODUCTION

1.1 Background

Removal of vegetation from land and construction of impervious surface

on it result in changes to surface runoff pattern (Goonetilleke et al., 2005),

increasing stormwater surface runoff and its peak flows (Al-Hamati et al.,

2010 and Barbosa et al., 2012). Hibbert (1967) mentioned that there is

clearly an increase in overland flow due to a reduction in forest cover; and

Hollis (1975) concluded that frequency of small floods increases many

times due to rapid urbanisation, while occurrences of large rare floods are

not significantly affected.

Increasing precipitation leads to large volumes of stormwater runoff; this

has been found to be one of the major causes of flash floods due to

decreasing rates of infiltration and ground water recharges (Liew et al.,

2012), The existing drainage systems are insufficient to carry the volume

of stormwater runoff during the precipitation periods. A conventional

approach practised in Malaysia is to allow developers to put in drains

where appropriate, but the government engineers determine the drain

sizes that will comply with the drainage capacity and final discharge outlet

1

POTENTIAL OF ROAD SUBSURFACE ON-SITE STORMWATER DETENTION SYSTEM

requirements. To maximise housing density, developers normally channel

all drainage to concrete-lined and open channel type of large trunk drains

(Zakaria et al., 2004).

The conventional drainage system in Malaysia is based on the first urban

drainage manual "Planning and Design Procedure No. 1: Urban Drainage

Design Standards and Procedure for Malaysia" which was published by the

Department of Irrigation and Drainage (DID) Malaysia in 1975. Drainage

designs based on this manual unfortunately have led to occurrences

of flash floods at the downstream of catchments, and therefore the

conventional drainage is no longer an effective measure in solving flood

problems (Zakaria et al., 2004).

In order to find more effective solutions, the above-mentioned manual was

superseded by another urban drainage manual known as Urban Storm Water

Management Manual for Malaysia (Manual Saliran Mesra Alam or MSMA). Water

Sensitive Urban Design (WSUD) has been implemented as the core of MSMA.

It is meant to control the quantity and quality of runoff through detention/

retention storages, infiltration facilities, and engineered waterways which are

capable of retarding the peak flows (Zakaria et al., 2004). The application of

MSMA, in the long term, helps to minimise the government allocation for flood

mitigation programmes. Among the many WSUD measures, On-Site Detention

(OSD) system is chosen as the focus of study in this research project.

1.2 On-Site Detention System

Stormwater detention provides flood-control benefits, by capturing

portions of urban runoff, and thus reduces the runoff volume. OSD systems

have been widely applied in Sydney since 1991; the developers provide

2

CHAPTER 1 INTRODUCTION

detention storages for stormwater on their project sites to limit rates of

runoff (O'Loughlin et al., 1995). Examples of such systems are highlighted

in Chapter 2.

1.3 Problem Statement

it is difficult to adopt the practice of OSD when large tracts of land

are not easily available. Therefore, this study project carries out

an experiment to use road subsurface rather than open spaces

for the purpose of OSD. Attempts are made to store stormwater

under the road to achieve the function of an OSD.

The design of the OSD system is in the form of constructed chambers

as a road subsurface layer. The details of the system are discussed

in Chapter 3. It is a rather new concept and therefore not much

information is available. In the context of hydrology, the extent

of such design to intercept urban runoff and its effectiveness as

an OSD are crucial to convincingly introduce this measure to the

community. A computer model would give a convenient simulation

and generate some performance results of such design.

1.4 Hypothesis

The surface runoff on roads can be directed to multi-unit storage

chambers under the road surface. The system should be able

to detain the stormwater over a period of time. Inlets therefore

should be efficient enough for the water to permeate through

them.

3

POTENTIAL OF ROAD SUBSURFACE, ON-SITE STORMWATER DETENTION SYSTEM

A hydrological study is always site specific, and the selected study area

is a typical residential area with low traffic roads in Kuching, Sarawak.

Simulation is carried out using EPA SWMM 5.0 software. The design of the

stormwater system is based on the guidelines as contained in the official

Malaysian manual, i. e. MSMA and SWMM.

1.5 Organisation of Monograph

The first chapter of this monograph is introduction to the study.

It consists of the general views of the topic, a problem statement

and outlined hypothesis.

The second chapter is literature review, in which important terms

and necessary information are explained in detail. This chapter

consists of the elaboration of WSUD, stormwater management,

OSD, and the modelling of the stormwater system.

The third chapter discusses the methodology and the procedures

used in order to test the hypothesis of this study. This chapter

explains the methods adopted for the research, which include

model building and assumptions made.

The fourth chapter covers results obtained from the usage of

methods adopted in Chapter 3. The results are elaborated and

evaluated in order to investigate the application of road subsurface

as OSD. The last chapter concludes the findings of this project and

presents recommendation for future studies.

4

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CHAPTER 2

LITERATURE REVIEW

2.1 Natural Hydrologic Cycle

Hydrology is the study of water and its properties, distribution, and effects

on the earth as it cycles through the earth's surface, subsurface, and

atmosphere (McCuen, 2005). Physical hydrologic processes that control

the distribution and movement of water in an area, over the surface of

the earth, and through the ground, are best understood in terms of the

hydrologic cycle.

The hydrologic cycle defines the naturally occurring processes that manage

water. It shows that the processes are interdependent, and the knowledge

of each is necessary to understand problems related to water quantity and

quality as well as their solutions. The whole cycle is ultimately driven by

solar radiation, which evaporates water from the ocean and lifts it up to

the atmosphere.

Figure 2.1 shows the processes of the hydrologic cycle system. The

complete hydrologic cycle consists of atmospheric, surface, subsurface

and interfacial processes. The atmospheric processes consist of cloud

condensation and precipitation; meanwhile, the surface processes

consist of snow accumulation, overland flow, river flow, and lake storage.

5


Infiltration, soil-water storage and groundwater flow are classified as

subsurface processes; meanwhile, evaporation, transpiration, sediment-

water exchange are interfacial processes. In short, the components of

hydrologic cycle are surface runoff, evaporation, transpiration, infiltration,

precipitation and groundwater storage.

plants open thcir porn for carbon dioxide and lose water to evaporation (trawpMatlan)

water vapor cools and changes back into liquid

form (condsnsatlon)

water, driven by the heat of the tun, changes into vapor and rises

into the air (evaporation)

Figure 2.1: Hydrologic Cycle (www. exploringnature. org)

Precipitation is the hydrologic cycle component that initiates runoff (Davis and Cornwell, 2008). As rain falls, it ultimately reaches the ground

surface. Some stormwater is intercepted by vegetation. Some is stored

in surface depressions, with almost all of that in the depression storage

infiltrating into the ground. Water stored in depressions, water intercepted

by vegetation, and water that infiltrates into the soil during the early

part of a storm represent the initial losses where it does not appear as

6


runoff during or immediately following a rainfall event. Once the ground is

saturated, stormwater starts to flow.

This overland flow is known as surface runoff. It flows on the ground

surface into ponds, lakes, streams or oceans and water from these bodies

are again evaporated back into the atmosphere. Water entering an upland

stream travels to increasingly larger rivers and then to the seas and

oceans. Infiltration occurs when water seeps into the ground and trapped

between rocks and soils as groundwater. The amount of water stored in

the soils determines, in part, the amount of rain that infiltrates during the

next storm event. Some of the water stored in the soil near the plants is

taken up by the roots of the vegetation, and subsequently transpires back

to the atmosphere from the leaves of the plants.

2.2 Urban Hydrologic Cycle

The natural hydrologic cycle is interrupted by rapid developments in urban

areas. As the population of the world Increases, changes to the land have

often been significant, with major alteration to the runoff characteristics

of watersheds. The biggest problem associated with urbanisation is the

increase in impervious surfaces. As defined by Chabaeva et at. (2009),

impervious surfaces are "artificial features, such as concrete surfaces,

pavements, and building rooftops that replace naturally pervious soils and

prevent precipitation from infiltrating the soil. " Spencer et at. (2009) and

Savary et al. (2009) agreed that land use change and impervious surfaces

have significant impacts on the hydrologic processes within a watershed

such as evapotranspiration and surface runoff. Urban watersheds are dominated by concentrated areas of human activities and are primarily

composed of impervious surfaces which partially eliminate the natural

7


processes that manage stormwater. This results in increased runoff

volumes and peak flows (Burns et al., 2005).

Over the last two centuries, urbanisation has caused significant changes to the landscape surrounding these urban centres (Sauer et al., 1981).

Continued growth results in increased capitalisation of the existing urban

areas and redevelopment to higher density housing. Some of these

activities are likely to be in flood-prone areas. For intense storm events,

where runoff exceeds the capacity of the local drainage system, flash flood

occurs.

2.3 Stormwater Management

Stormwater management is the mechanism for controlling stormwater

runoff. Best Management Practices (BMPs) are documented worldwide to

assist authorities for the mentioned purposes. Different approaches can be

followed to deal with stormwater: strategic decisions, political decisions,

source control or "end of pipe measures" (German et al., 2005).

In countries like the United States of America, the United Kingdom and

Australia, stormwater management is applied not only to the overall

stormwater management facilities (for example, regional ponds and

wetlands), but to individual homes through BMPs. Their holistic approaches

towards stormwater management have resulted not only in the reduction

of flash floods, but also improved environments through replenishment of

groundwater tables.

BMPs are design techniques used to achieve the desired post-development hydrologic conditions. BMPs deal with stormwater by taking into account


both future needs and the protection of natural resources (Hvitved-

Jacobsen et al., 2010). Non-structural BMPs are practices designed to limit

the generation of stormwater runoff or reduce the amounts of pollutants

contained in the runoff. They minimise the total disturbed area, soil

compaction and cluster development. On the other hand, structural BMPs

are engineered and constructed systems that improve the quality and

control the quantity of stormwater. These include bio-retention facilities,

detention basins, vegetated systems, infiltration trenches, pervious

pavements and rainwater harvesting (Martin et al., 2007).

2.4 Water Sensitive Urban Design

WSUD introduces a range of measures that are designed to minimise the

impacts of urbanisation. According to Melbourne Water (2002), WSUD

marks a shift in thinking towards stormwater management where all water

streams are considered as a resource. All city sites, including buildings,

roads, footpaths and open spaces can contribute to sustainable water

resources management across the municipality.

The concept of WSUD is to reduce the volume and speed of stormwater

runoff in drainage systems. Other than that, WSUD also serves to protect

natural waterways within urban development, to Integrate stormwater

treatment into the landscape, to protect the water quality of receiving

waterways and bays by removing pollution close to their sources, to

manage the stormwater locally as it flows from upstream in order to

reduce the need for bigger drainage infrastructure downstream and to

reduce the overall cost of drainage infrastructure.

9


In an attempt to compensate for the loss of natural storage, many

localities require the replacement of the lost natural storage with man-

made storage. Detention basins are one of the WSUD measures. It is

a stormwater structure that provides temporary storage of stormwater

runoff. Its primary purpose is to attenuate stormwater flow, which leads

to reduction of peak runoff rates.

They are separated into on-site and regional detention (DID, 2012).

The design of stormwater detention basins requires the knowledge of

water routing through the hydraulic outlet structure and the knowledge

about surface runoff into the detention basin. In some detention basins,

infiltration process is incorporated (Gribbin, 2001). The importance of

storing stormwater runoff in large basins has been well recognised (Dunne

and Leopold, 1978; Whipple, 1979).

Figure 2.2 shows the requirement that the quantity of surface runoff from

developing area should be maintained to near pre-development condition.

Post Development Uncontrolled Runoff

----- Pre-Development Uncontrolled Runoff

Post-Development Controlled Runoff by Detention

Time

Figure 2.2: Scenarios of Hydrograph (Sidek et al.; Zakaria et al., 2004)

10


Peak runoff can be reduced through the implementation of BMPs:

detention tanks, retention ponds or sedimentation basins, wetlands, green

roofs, bio-retention swales, porous pavements, etc. Reduction in peak

runoff can be achieved by using one or a combination of the mentioned

measures, depending on the availability of space, intended functions of

the stormwater management system, and costs.

2.5 On-Site Detention

Storage facilities are the core elements of achieving one of the major

stormwater quantity control criteria - the post-development peak discharge cannot be more than the pre-development peak discharge.

An OSD system provides storages for stormwater to compensate for the

increased runoff from the development. It was first introduced and widely

used in Australia as a means of controlling the increased storm discharges

from urban consolidation projects (O'Loughlin et al.; Phillips, 1995). With

proper placing and sizing of the storage facilities (Guo, 1999), these

systems are considered the major type of stormwater control system in

urban areas (ASCE, 1992).

Detention storages collect and store stormwater runoff during a storm

event, then release it at controlled rates to the downstream drainage

system, thereby attenuating peak discharge rates from the site. With such

a system in place, the drainage system as a whole can cater for higher

intensity storms brought about by increasing uncertainties due to climate

change.

OSD identifies an entire plethora of storage facilities which are present in

the upper reaches of the flow conveyance system. The primary difference

11


of OSD with local disposal and inlet control facilities is in the amount of

tributary area being intercepted. OSD generally intercepts runoff from

several pieces of real estates or from an entire subdivision. This means

the water has been conveyed at least a short distance before it arrives at

the detention facility.

Figure 2.3 shows the typical OSD facilities. OSD can be provided above

ground, below ground, or a combination of both (DID, 2012). The above-

ground storages (basically as tanks) can be located on rooftops, lawns,

gardens, car parks, driveways, etc. It is easy to construct and cheaper

than below-ground storage as it does not require much piping system.

Rooftop

,- Landscaped Area 0000 ' 000o , ý-ý�ýý

Underground Tank Pipe Package --

I

Figure 2.3; Typical On-Site Detention Storage Facilities (DID, 2012)

On the other hand, the below-ground storages consist of tanks and pipe

packages. The author would like to add two more types, namely chamber

and modular blocks. These storages are used in developed areas where

land cost and/or availability are of major concerns (Al-Hamati et al., 2010).

The concept of OSD system also can be similar to wetland's function that

12

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