Malaysian Sewerage Industry Guideline (Volume III) 1st Edition

First Edition

Volume III Sewer Networks and Pump Stations Published by : Suruhanjaya Perkhidmatan Air Negara (SPAN)

Ministry of Energy, Water and Communication Malaysia

Foreword by the CEO of SPAN

M

unicipal wastewater treatment technology in Malaysia has evolved through several eras. In the past, only basic facilities were used, e.g. overhang latrines, pit privy, bucket systems and pour flush systems. Some improvement were observed when more modern system like septic tank and Imhoff tank systems were introduced into the country some 40 years ago. The municipal wastewater treatment in Malaysia sees a significant improvement in the last three decades since the introduction of new technologies in the form of oxidation ponds, aerated lagoons, activated sludge system, package systems and a variety of mechanical plants into the country. However, sewage still remains as one of the major pollutants of our inland waterways. In the 1900s, the emergent of new treatment technologies were mainly driven by the basic need to treat the sewage so as to control waterborne diseases. Today, the environmental regulations are becoming stringent with the increasing awareness toward sustainable environmental management. Allowable effluent discharge limits are becoming lower globally. Public are also more educated and more alert on the needs to preserve the environment. Hence the evolution of municipal wastewater treatment technologies now are even more revolutionary and more rapid in order to meet the stricter regulators’ requirements and to compete in the increasing competitive market. While the nation moves towards achieving the status of a developed country, sustainability of our environment, in particularly the Malaysian rivers and streams must be strengthened. With this vision in mind, the Sewerage Services Department published its first edition of the guidelines for sewerage industry titled “Design and Installation of Sewerage Systems” in January 1995. The main purpose of these guidelines is to assist the

developer and his designer to plan and design systems acceptable to the regulatory authorities which, in turn speeds up the approval processes. The Guidelines has clearly guided the nation sewerage industry towards achieving an improved sewerage system in the country. Subsequently, the Department further improvised the Guidelines in its second edition titled “Guidelines for Developers” which comprise five volumes covering specific topics. As a continuation to the efforts by the Sewerage Services Department, the National Water Services Commission undertake to revise and improvement the Guidelines for Developers. The product of the revision is “Malaysian Sewerage Industry Guidelines” which also comprise five volumes. These new revisions incorporated valuable knowledge gained by various stakeholders over a decade since the implementation of the first Guidelines for Developers and upkeep with the aim towards sustainable environmental management. Volume 1 Volume 2 Volume 3 Volume 4 Volume 5

-

Sewerage Policy for New Developments Sewerage Works Procedures Sewer Networks and Pump Stations Sewage Treatment Plants Septic Tanks

Volume 3 is specifically developed to provide a clear understanding of policies of the SPAN for the provision, refurbishment or upgrading of sewer networks and pumps stations. This volume covers planning, design, material selection, construction, installation and sewer testing requirements. The implementation of these guidelines since 90’s has undoubtedly achieved some levels of consistency in the design and construction of sewerage network nationwide. Finished sewerage networks quality has also been elevated while the operation and maintenance of the plants have improved significantly in terms of safety, health, operability and robustness. Whilst the adherence to these guidelines is necessary, engineering discretion is also required, especially for large sewers and pumping station with special situations. It is hoped that the publication of the third edition of this Volume further improve the municipal wastewater treatment facilities in this country. Dato’ Teo Yen Hua Chief Executive Officer SPAN

Copyright National Water Services Commission, Ministry of Energy, Water and Communications, 2008

All rights reserved.

This publication is protected by copyright.

No part of this publication may be reproduced, distributed, transmitted, stored in a retrieval system, or reduced to any electronic medium without the written authority of the Commissioner, National Water Services Commission, Ministry of Energy, Water and Communications,.

National Water Services Commission and Registered Certifying Agencies employees are permitted to copy and use the information in this publication, for internal purposes only.

Changes may be made periodically to the information herein.

TABLE OF CONTENTS Section 1

PAGE

Introduction

1.1

Purpose of This Volume

1

1.2

WhoShouldUseThisVolume

1

1.3

RelatedReferenceMaterial

Section 2 2.1

1

Planning, Material and Design Sewers

9

2.1.1

PipeMaterialSelectionFactors

9

2.1.2

PipeMaterialsandFittings

2.1.3

Pipe Selections

2.1.4

Requirements and Limitations for Use of Certain Pipe Material 11

2.1.5

VitrifiedClayPipe

2.1.6

ReinforcedConcretePipe

2.1.7

Ductile Iron Pipe

2.1.8

Steel Pipe

2.1.9

Solid Wall PE Pipe

2.1.10 2.1.11

ProfiledWallPEPipe GlassReinforcedPlasticPipe

2.1.12

Acrylonitrile Butadiene Styrene Pipe

18

2.1.13

Sewer Design - General Requirements

18

2.1.14

FlowRateEstimations

2.1.15

SewerCleansingVelocities

10 11

13 14 15 15 16 16 17

19 20

2.1.16

Pipe Roughness

2.1.17

DesignofGravitySewer

21

20

2.1.18

DesignofForceMains

23

2.1.19

VacuumSewerageSystem

25

2.1.20

ComputerisedSewerDesigns

36

2.1.21

DesignofInvertedSiphon

37

2.1.22

StructuralDesignofSewers

37

2.2

Manhole 2.2.1G

2.3

2.2.2

Manhole Location

2.2.3

PipeLengthsfromManhole

2.2.4

Structural Design Considerations for Manhole

ManholeCoversandFrames 2.3.1G

2.4

40 eneral

40 42 42 43 44

eneral

2.3.2 2.3.3

Load Class Material

2.3.4

Dimensions, Marking and Surface Finish

44 44

44

44

2.3.5S

eating

44

2.3.6C

asting

45

2.3.7

ProtectiveCoating

2.3.8

Water-tightness

2.3.9

Safety Features

2.3.10

ProductCertification

DesignofNetworkPumpStations

45 45 45 45 46

2.4.1

Specifying of Network Pump Stations

46

2.4.2

GeneralRequirements

46

2.4.3

BufferRequirements

47

2.4.4

PipeworkRequirements

47

2.4.5

Wet-wellRequirements

48

2.4.6

Dry-wellRequirements

48

2.4.7

StructuralRequirements

49

2.4.8

VentilationRequirements

49

2.4.9

Odour Control

2.4.10

Requirements for Lighting and Electrical Fittings

50

2.4.11

Acceptable Pump System (Fixed Speed Pumps Only) 50

2.4.12

ValveRequirements

50

51

2.4.13 Requirements for Level Controls

52

2.4.14

RequirementsforAlarms

52

2.4.15

Requirements of Hydraulic Design and Performance52

2.4.16

MaintenanceConsiderations

2.4.17

HazardandOperability

2.4.18 OtherRequirements

52 53 53

2.5

2.6

Interceptors

56

2.5.1

Oil Interceptors

56

2.5.2

Grease Traps

56

Concrete and Reinforcement Requirements 2.6.1

Concrete

2.6.2

Cement

2.6.3

Steel Reinforcement and Falsework

56 57 57 57

Section 3

Construct ion and Installation

3.1

Introduction

3.2

PipesandFittingsDeliveryandHandling

3.3

3.4

3.5

3.6

3.7 3.8

59 59

3.2.1

Pipes and Fittings Delivery

59

3.2.2

Pipe Handling at Site

60

3.2.3

Pipe Storage

61

3.2.4

Pipe Damage

Trench Excavation

62

63

3.3.1

Protection of Affected Services, Structures, Pavements 63 and Vegetation

3.3.2

Excavation Requirements

3.3.3

Bored Excavation

Pipe Laying

64 66

66

3.4.1

Pipe Bedding

66

3.4.2

Pipe and Fittings Placement

67

3.4.3

Pipe Jacking

68

3.4.4

Concrete Pipe Support

68

3.4.5

Pipe Cutting

69

3.4.6

Backfill of Trench

69

Pipe Jointing

70

3.5.1

Flexible Joints

70

3.5.2

Solvent Weld Joints

71

3.5.3

Flanged Joints

72

3.5.4

Steel Pipe Welded Joints (Field Welding)

72

3.5.5

Polyethylene Butt Welded Joints

SpecialRequirementsForSewer

73

73

3.6.1

Thrust Blocks for Pressure Pipelines

73

3.6.2

Pipe Restraints and Bulkheads on Steep Slopes

74

3.6.3

Pipe Embedment and Overlay

74

3.6.4

Sleeving of Ductile Iron Pipe

75

Reinstatement ConnectionstoPublicSewers

76

75

3.8.1

General

76

3.8.2

Junction Connections

77

3.8.3

Saddle Connections

77

3.8.4

Manhole Connections

78

Section 4

Sewer Testing 4.1

General

4.2

TestingofGravitySewers

80

4.3

TestingofForcedMains

81

4.4

TestingofManholeandotherancillaries

4.5

Low Pressure Air Test

4.6

4.7

4.8

79

81 82

4.5.1

General

82

4.5.2

Procedure for Testing

82

4.5.3

Procedures for Handling Air Test Failure

83

LowPressureWaterTest

84

4.6.1

General

84

4.6.2

Procedure

84

4.6.3

Handling Water Test Failures

HighPressureWaterTest

85

86

4.7.1

General

86

4.7.2

Procedure

86

HighPressureLeakageTest

87

4.8.1

General

87

4.8.2

Procedure

87

4.9

Test for Straightness, Obstruction, and Grade

88

4.10

CCTV Inspection

88

4.10.1

Objectives of C CTV Inspection

89

4.10.2

Technical Requirements and References

89

4.10.3

Equipment Specifications and Test Devices

89

4.10.4. CCTV Inspection Requirements

4.11

4.12

90

4.10.5

CCTV Inspection Implementation Procedure for New 91 Sewer Network

4.10.6

Interpretation Of Results From CCTV Inspection

93

4.10.7

Follow -Up Action to Be Taken

93

Infiltration Test 4.11.1 4.11.2

General Procedure

4.11.3

Handling Test Failures

Water-tightness Test

95 95 95 95

95

4.12.1

General

95

4.12.2

Procedures

96

LIST OF TABLES Table 2.1a

Normal Pipe Roughness for Gravity Sewer

Table 2.1b

Normal Pipe Roughness for Force Mains for All Pipe Materials 21

Table 2.2

Typical Roughness Coefficient, k

22

s

22

Table 2.3

Typical Manning Coefficient, n

Table2.4

Typical Hazen-Williams Coefficient,C

Table 2.5 Table2.6

Condition/alarm of the station equipment MinimumManholeDiameters

Table2.7

Finalinspectionandtesting

Table 2.8 Table 4.1

23 36 41 46

Recommended Design Parameters for Pump Stations Test Duration

Table4.2

Appendix A

54

83

DefectGradesDescriptions

94

Typical Drawings/ D iagrams

FigureA1

StandardManholeCover

FigureA2

PlanViewofTypicalManhole

Figure A3

21

98 99

Typical Shallow Precast Concrete Manhole (Ground Level to Invert of Pipe 1.2m

≤ Depth <2 .5m

100

Figure A4

Typical Shallow Precast Concrete Manhole with Backdro

Figure A5

Typical Medium Precast Concrete Manhole

Figure A6

Typical Medium Precast Concrete Manhole with backdrop

Figure A7

Typical Deep Precast Concrete Manhole

Figure A8

Typical Deep Precast Concrete Manhole with Backdrop

Figure A9

Typical Details of Large Diameter Manhole (LDM) Type 106

(Ground Level to Invert of Pipe 1.2m



(Ground Level to Invert of Pipe 5m

(Ground Level to Invert of Pipe 5m

FigureA10 Figure A11 Figure A 12

≤ Depth <2 .5m)

101

≤ Depth <5 m)

102

≤ Depth <5 m)

≤ Depth ≤9 ≤ Depth ≤9

103

m)

104

m)

TypicalInductVentDetail Details of Household Connection to Main Sewer ReticulationPipeforV.C.Pipe Typical Details of Concrete Thrust and Anchor Block

105

107 108 109

Figure A13a Typical Details of Inverted Siphons or Depressed Sewer (Sheet 2) of1 110

Figure A13b Typical Details of Inverted Siphons or Depressed Sewer (Sheet 2) of2 111 Figure A14

Typical Details of Receiving Manhole, Force Main and Washout Valve 112

Figure A15

Precast Concrete Chamber (Type A ) and Details of Air ValveandScourValveChamber 113

FigureA16

StandardPipeBeddings

FigureA17

Vacuumsewagecollectionsystem

114 115

FigureA18 Houseconnection 115 Figure A19a Example of vacuum station with housed collection vessel116 Figure A19b Example of vacuum station with housed collection vessel117 Figure A20a Collection chambers with interface valves vented through breather pipes 118 Figure A20b Collection chamber with interface valve activated by float118 FigureA20c Multi-valvecollectionchamber

119

Figure A21

Vacuum sewer profiles (not to scale)

Figure A22

Example of vacuum sewer profiles for uphill and downhill transport(nottoscale) 120

FigureA23 Figure A24

Y-branchforvacuumsewer

120

121

Method of joining crossover pipes and branch sewers to vacuum mains 121

Figure A25

Typical details of dry-well pump station

122

Figure A26

Typical detail of wet-well pump station

123

Figure A27

Buffer Zone for Pump Station with Super Structure

124

Figure A28

Buffer Zone for Pump without Super Structure

125

Figure A29

Buffer Zone for Pump without Super Structure

126

Appendix B

Tables

Table B1 : Classes of Rigid Pipe Required for Various Depth

Appendix C

127

CCTV Format and Codes

Appendix C 1 Report format for CCTV Inspection

129

Appendix C 2 Report format for CCTV Inspection Appendix C 3 Report format for CCTV Inspection

130 131


132


133

Appendix C 6 Module

134

Section 1 Introduction

Introduction

1. 1

Purpose of This Volume This volume sets out the requirements of the National Water Services Commission (SPAN) (referred to as the Commission in this document) for the design, construction and testing of sewer networks and network pump stations. The owner must comply with the requirements set out in this volume when submitting an application for the approval of the Commission. This volume generally does not cover internal plumbing systems within buildings. However, some guidelines are provided on the provision of interceptors to protect public sewers from the discharge of oil and grease from garage workshops, hotels, restaurants, canteens or any premises that collect such matter.

1. 2

Who Should Use This Volume This volume is primarily intended for owners, developers, consulting engineers, sewerage contractors, manufacturers, planners, and Public Authorities who have a direct interest in the planning, design and installation of sewer networks and/or network pump stations.

1. 3

Related Reference Material This volume does not cover all aspects of design and construction of sewer networks and network pump stations. Where information is not covered in this volume, the designer shall follow the requirements given in MS 1228. MS 1228 shall take precedence over other foreign standards in the event when there are discrepancies on the requirements. The following documents are also referred to in this volume.

a)

Malaysian Standards i.

MS 28

Specification for test for water for making concrete

ii.

MS 29

Specification fo r ag gregates from n atural so urces fo r concrete

iii.

MS 144

Specification for cold reduced mild steel wire for reinforcement of concrete

iv.

MS 145

Specification for steel welded fabric for the reinforcement of concrete.

v.

MS 146

Specification of concrete. for hot rolled steel bars for the reinforcement

vi.

MS 522

Specification for Portland cement (ordinary and rapid hardening)

vii.

MS 523

Specification for concrete including ready mixed concrete

viii.

MS 628

Specification for unplasticised PVC (uPVC) pipes for water supply

Sewer Networks and Pump Stations

Volume 3

1

Introduction

Part 1 : Pipes Part 2 : Joints and fittings for use with unplasticised PVC pipes ix.

MS 672

Specification of rubber seals in water supply, drainage and sewerage pipelines

x

MS 740

Specification for hot-dip galvanized coatings on i ron and steel articles

xi.

MS 822

Specification for sawn timber foundation piles

xii.

MS 881

Specification for pre-cast concrete pipes and fittings for drainage and sewerage Part 1: Specification for pipes and fittings with flexible joints and manholes

xiii.

MS 922

Specification for concrete admixtures Part 1 : Accelerating admixtures, retarding admixtures and water-reducing admixtures

MS 923

Specification for joints and fittings for use with uPVC pressure pipes [delete] Part 3: Mechanical joints and fittings, principally of uPVC [delete]

xiv.

MS 979

Specification for unplasticizes sewerage pipes and fittings Part 1: Pipes of diameter 100mm and 155mm Part 2: Pipes of diameter 200mm and above

xv.

MS 980

Specification for safety signs and colours : Colorimetric and photometric properties of materials

xvi.

MS 981

Specification for safety signs and colours : Co lour and design

xvii.

MS 982

Specification for fire safety signs, notices and graphic symbol

xviii.

MS 1037

Specification for sulphate-resisting Portland cement

xix.

MS 1058

MS 10 58 Specification for polyethylene (PE) pip ing systems for water supply Part 1 : General Part 2 : Pipes

2

xx.

MS 1061

Vitrified clay pipes and fittings and pipe joints for drains and sewers

xxi.

MS 1195

Code of practice for structural use of concrete

xxii.

MS 1227

Specification for Portland pulverised fuel ash cement

xxiii.

MS 1228

Code of Practice for Design and Installation of Sewerage Systems

xxiv.

MS 1347

Cathodic Protection : Part 1 Code of practice for land applications

xxv.

MS 1292

Specification for rubber seals – water stop for sealing joints in concrete – Specification of materials

xxvi.

MS 1389

Specification for Portland blastfurnace cement

Volume 3

Malaysian Sewerage Industry Guidelines

Introduction

xxvii .

MS EN Specification for general criteria for certification bodies 45011 operating product certification.

xxvii i.

MS ISO/IEC Guide 65

General requirements certification systems

04Z005R0

Air Quality – Determination of odour concentration by dynamic olfactometry. [ KIV. To be discussed in the Main Committee Meeting ]

xxix

b)

for

bodies

operating

product

BS 65 Standards i.British Specification for vitrified clay pipes, fittings and ducts, also flexible mechanical joints for use solely with surface water pipes and fittings BS 915

Specification for high alumina cement. Metric unit.

iii.

BS 3416

Specification for bitumen-based coatings for cold application, suitable for use in contact with potable water

iv.

BS 3692

ISO metric precision hexagon bolts, screws and nuts. Specification.

v.

BS 4147

Specification fo r bitumen b ased h ot a pplied c oating materials for protecting iron and steel including suitable primers where required

vi.

BS 4164

Specification for coal-tar-based hot-applied coating materials for protecting iron and steel including a suitable primer

vii. viii.

BS 4248 BS 4515

Specification for Supersulfated cement Specification for welding of steel pipelines on land and offshore.

ix.

BS 5153

Specification for cast iron check valves for general purposes.

x.

BS 5480

Specification for Glass Reinforced Plastic (GRP) pipes, joints and fittings for use for water supply or sewerage

xi.

BS 5911

Part 1 : Precast concrete pipes, fittings and ancillary products. Specification for unreinforced and reinforced concrete pipes (including jacking pipes) and fittings with flexible joints (complementary to BS EN 1916)

ii.

xii.

BS 5975

Code of practice for falsework.

xiii.

BS 6076

Specification for polymeric film for use as a protectiv sleeving for buried iron pipes and fittings (for site and factor application)

xiv.

BS 6105

Specification for corrosion resistant stainless steel fasteners. [delete]

xv. BS 7123


Specification for metal arc welding of steel for concrete reinforcement.

BS 7874

Method of test for microbiological deterioration elastomeric seals for joints in pipework and pipelines.

BS 8005

Sewerage [delete]

Volume 3

3

of

Introduction

xvi. BS 8007

Code of practice for design of concrete structures for retainin aqueous liquids

xvii. BS 80102.1

Code of practice for pipelines. Pipelines on land : design, construction and installation. Ductile iron

xviii.

BS 8666

Specification for scheduling, dimensioning, bending and cutting of steel reinforcement for concrete.

xix. BS EN 124 Gully tops and manhole tops for vehicular and pedestrian areas. Design requirements, type testing, marking, quality control BS EN 295 Specification for vitrified clay pipes and fittings with flexible mechanical joints [delete] Part 7: Requirements for vitrified clay pipes and joints for pipe jacking [delete] xx. BS EN 295-1

Vitrified clay pipes and fittings and pipe joints for drains and sewers. Requirements

xxi. BS EN 295-7

Vitrified clay pipes and fittings and pipe joints for drains and sewers. Requirements for vitrified clay pipes and joints for pipe jacking xxii. BS EN 545 Ductile iron pipes fittings and accessories and their joint for water pipelines – requirements and test methods xxiii. BS EN 598 Ductile iron pipes fittings and accessories and their joint for sewerage applications – requirements and test methods. xxiv. BS EN 681

Elastomeric seals. Materials requirement for pipe joint seals

used in water and drainage applications. xxv. BS EN 682 Elastomeric seals. Materials requirement for pipe joint seals used in pipes and fittings carrying gas hydrocarbons fluids. xxvi. BS EN 752 Drain and sewer systems outside buildings xxvii. BS EN 1091

Vacuum sewerage systems outside buildings

xxviii. BS EN 1561 xxix.

Specification for flake graphite cast iron

BS EN 1563

xxx. BS 1982

Specification for spheroidal graphite or nodular graphite cast iron EN

Copper and copper alloys. Ingots and castings.

xxxi. BS EN 10025

Hot rolled products of non-alloy structural steels.

xxxii BS

EN

Seamless and welded steel tubes. Dimensions and masses

10220 xxxiii. BS EN 10224

per unit length. Non-alloy steel tubes and fittings for the conveyance of aqueous liquids including water for human consumption. Technical delivery conditions.

xxxiv. BS EN 10277

Bright steel products. Technical delivery conditions. Part 1 : General Part 2 : Steels for general engineering purposes

4

Volume 3


Introduction

Part 3 : Free cutting steels Part 4 : Case-hardening steels Part 5 : Steels for quenching and tempering x xxv BS EN 10278

Dimensions and tolerances of bright steel products.

x xxvi BS EN 13725

Air quality – Determination of odour concentration by dynamic olfactometry.

xx xvii BS EN ISO Construction drawings. Simplified representation of concrete 3766 reinforcement. xx xviii BS EN ISO Mechanical properties of corrosion-resistant stainless-steel 3506 fasteners Part 1 : Bolts, screws and studs. Part 2 : Nuts.

c)

Australian / New Zealand and Australian Standards i. AS/NZS 1260 ii. AS/NZS 1477

PVC-u pipes and fittings for drain, waste and vent application (refer to uPVC profiled wall pipe only) PVC pipes and fittings for pressure applications

iii. AS/NZS 2566

Buried flexible pipelines Part 1 : Structural design

iv. AS/NZS 3518

Acrylonitrile Butadiene Styrene (ABS) compounds, pipes and fittings for pressure applications.

v. AS/NZS

Supplementary cementitious materials for use with portland

3582

and blended cement Part 3 : Amorphous silica.

vi. AS/NZS 4323

Stationay source emissions

vii. AS 3725 viii. AS 3750.2 AS 3750.12 ix. AS 3751 x AS 3996 xi AS 4060

d)

Part 3 : Determination of odour concentration by dynamic olfactometry. Loads on buried concrete pipes Paint for steel structure – Ultra high-build piant. Paint for steel structure – Alkyd/micaceous iron oxide. Underground mining – Slope haulage – coumplings, drawbars and safety chains. Metal access covers, road grates and frames Loads on buried vitrified clay pipes

German Standards i.

DIN 16961

Thermoplastic pipes and fittings with profiled outer and smooth inner surfaces Part 1: Dimensions Part 2: Technical delivery conditions


Volume 3

5

Introduction

e)

International Standards i.

ISO 1083

Spheroidal graphite cast irons - Classification

ii.

ISO 3506

Mechanical p roperties o f co rrosion-resistant sta inless-steel fasteners

iii.

f)

ISO 10465

TR

Underground installation of flexible glass-reinforced thermosetting resin (GRP) pipes Part 1: Installation procedures Part 3 : Installation parameters and application limits

Industry Specifications (U.K) i. Water WIS 04-32Specification for PE 80 and PE 100 spigot fittings and drawn 15 bends for nominal sizes up to and including 1000 ii.

WIS 01

04-24-

Specification for mechanical fittings and joints for polyethylene pipes for nominal sizes 90 to 1000

iii.

WIS 14

04-32-

Specification for PE 80 and PE 100 electrofusion fittings for nominal sizes up to and including 630

g)

American Society for Testing and Material i.

ASTM 3262

D

Specifications for “Fiberglass” Glass-Fibre-Reinforced Thermosetting- Resin Sewer Pipe

ii.

ASTM 2321

D

Practice for Underground Installation of Flexible Thermo Plastic Sewer Pipe

iii.

ASTM F 894

iv.

ASTM 3350

D

Specification for Polyethylene (PE) Large Diameter Profile Wall Sewer and Drain Pipe Standard Specification for Polyethylene Plastics Pipe and Fitting Materials

v.

ASTM 3212

D

h)

Standard Specification for Joints for Drain and Sewer Plastic Pipes Using Flexible Elastomeric Seals

Other Reference Materials i.

Simplified Tables of External Loads on Buried Pipelines - UK Transport Research Laboratory

The Commission will, from time to time, specify additional standards to be used in the design and construction of sewerage works. These standards shall be referred to as appropriate for the design and construction of sewer networks and network pump stations. All standards used in the design and construction of sewerage works shall be the latest or the most updated. When any one of the above mentioned standards is withdrawn or superseded, the latest or updated standards shall be referred to as appropriate. This shall be the same for any applicable act, guideline, by-law, etc. related to sewerage works endorsed by the government.

6

Volume 3


Introduction

Other Guidelines in This Set The Malaysian Sewerage Industry Guidelines comprise of 5 volumes:

♦ ♦ ♦ ♦ ♦

Volume I Volume II Volume III Volume IV Volume V


Sewerage Policy for New Development Sewerage Works Procedures Sewer Networks and Pump Stations Sewage Treatment Plants Septic Tanks

Volume 3

7

Introduction

8 (this page is intended to be blank)

Volume 3


Section 2 Planning, Material and Design

Planning, Material and Design

2.1

Sewers

2.1.1

Pipe Material Selection Factors The following considerations are the important factors to be considered before selecting or approving any pipe material and pipeline system for sewer networks. a)

Resistance to acidic condition of which is prevalent in sewer networks in tropical climates

b)

Resistance to sulphate attack from aggressive soils and groundwater

c)

Resistance to corrosion in contaminated soils

d)

Resistance to severe abrasion from sewage flow and usual cleaning methods

e)

Resistance of the joint to groundwater entry (infiltration) and sewage escape (exfiltration)

f)

Resistance of the joint material to corrosion and microbiological degradation

g)

Structural damages and other damages that may occur in handling

h)

Handling, laying and jointing care and difficulties

i)

Methods of pipe embedment to ensure structural performance

j)

Maintenance of structural strength and performance in service

k)

Methods of maintenance and repair

l) m)

Cost of supply, transportation and installation Range and suitability of fittings where considered for smaller diameter sewers

n)

Previous local experience

o)

Local availability

p)

Pipe pressure ratings

q)

The design life of a pipe shall be at least 50 years.

r)

All bolts and nuts shall be stainless steel (SS) 304.

s)

Where necessary, special tools and trained personal shall be made available during handling and installation of pipes.

Additionally, the following factors should be considered before selecting or approving any pipe manufacturer and supplier. a)

Compliance of products to standards

b)

Compliance to additional material and product requirements specified by the Commission

c)

Quality control and assurance practised by the manufacturer and supplier to ensure good pipe product quality from manufacturing to delivery


Volume 3

9


2.1.2

Pipe Materials and Fittings There is an extensive range of pipe materials available in Malaysia for use for gravity, pressure and vacuum sewers. The materials and the standards which the pipes are required to conform to are as follows:

10

a)

Vitrified clay (VC) i) MS 672 ii) MS 1061 iii) BS EN 295

b)

Reinforced concrete (RC) i) MS 881 ii) BS 5911 iii) BS 7874 iv) BS EN 681 v) BS EN 682

c)

Ductile iron (DI) i) BS EN 598

d)

Mild Steel i) BS EN 10025 i) BS EN 10224

e)

Stainless St eel i) BS EN 10220

f)

Polyethylene (PE) solid wall i) MS 1058 ii) WIS 04-32-15 iii) WIS 04-32-14 iv) WIS 04-24-01

g)

Unplasticised polyvinyl chloride (uPVC) solid wall i) MS 628 : Part 2 : Section 2 ii) MS 923 iii) MS 979 iv) AS/NZS 1477

h)

Polyethylene profiled wall i) DIN 16961

i)

Unplasticised polyvinyl chloride profiled wall i) AS/NZS 1260

j)

Glass reinforced plastic (GRP) i) BS 5480 ii) AS 3571

k)

Acrylonitrile butadiene styrene (ABS) i) AS/NZS 3518

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Marking of all pipes shall comply with available Malaysian or British Standards where applicable. Additional requirements to those given in the above standards may be specified from time to time by the Commission.

2.1.3

Pipe Selections Except where otherwise specifically approved by the Commission, the pipe materials to be used for a specific type of sewer are listed below: 1)

Gravity sewers a) i) Rigid VC pipes ii) RC

b)Flexible i) GRP pipes ii) Ductile Iron iii) HDPE (Profile)

2)

Force mains (Rising mains) i) Ductile Iron ii) GRP iii) ABS iv) HDPE (Solid) v) Steel

3)

Vacuum sewers i) ABS – for internal use ii) HDPE (Solid) – for external use

There are specific requirements such as pipe class, joint type, linings etc. which the above approved pipe materials must meet in order to suit the above applications. Also, there are certain limitations for use of each pipe type. These requirements and limitations are specified in the following sections. From time to time, the Commission will publish sewer selection guides which will provide more detailed direction on the selection and use of sewer materials. For other pipe materials not listed above, their use will be given considerations in special circumstances. However, only pipes and fittings from manufacturers and suppliers approved by the Commission are permitted to be used for sewerage applications.

2.1.4

Requirements and Limitations for Use of Certain Pipe Material Unless the exemption is granted by the Commission, the following limitations or requirements shall be followed when selecting the pipe materials:

1)

Gravity Sewer

a)

VC i. ii.


Only size 150 mm or above shall be used The minimum size for public sewer shall be at least 225 mm

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11


iii.

Pipe shall not be used in unstable ground

iv.

Flexible joints are recommended

b)

RC i. ii. iii.

c)


GRP Pipe shall not be used in ground contaminated with high concentration of chemicals such as solvent that can degrade the pipe

ii.

Pipe shall not accept any industrial or other aggressive discharges that may affect the pipe integrity

iii.

Pipe shall be used only when no fittings are required

iv.

Only sizes 600 mm or above are allowed

DI i.

The use is only allowed for applications needed high pipe strength

ii.

Pipe protection linings and coatings are required

iii.

Polyethylene sleeving is required for all buried applications

HDPE i.

Pipe shall not be used in ground contaminated with high concentration of chemicals such as solvent that can degrade the pipe

ii.

Pipe shall not accept any industrial or other aggressive discharges that may affect the pipe integrity.

iii.

Only pipe with profile wall is permitted.

2)

Force Mains

a)

DI i. ii.

12

Only sizes 600 mm or above are allowed in compliance to the policy

i.

d)

e)

Pipe protection linings are required

Pipe shall not be used in unstable ground Pipe protection linings and coatings are required

iii.

Polyethylene sleeving is required for all buried applications

iv.


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b)

c)

GRP i.


ii.


iii.

Fittings shall be made of ductile iron

iv.

Only sizes 600 mm or above are allowed

ABS i. ii.

d)

e)

2.1.5

Where VC or RC pipes are not suitable Only for nominated projects or as permitted by the relevant authority

HDPE i.


ii.


Steel i.

Pipe is allowed only for sizes 700 mm or above

ii.

Pipe protection linings and coatings are required

Vitrified Clay Pipe Vitrified clay (VC) pipe is manufactured in Malaysia in diameters of 100 mm to 600 mm and lengths ranging from 0.91 m to 2.50 m. Larger diameters of VC pipe are imported. VC pipes are classified according to the pipe ring crushing strength which depends on the manufacturing process and quality. VC pipes and fittings can be produced either unglazed or glazed on the interior and/or exterior. When glazed they need not be glazed on the jointing surfaces of the spigot and socket. VC pipes which are available in Malaysia are normally manufactured with spigot-socket flexible joints. Most manufacturers commonly offer a rubber ring seal. However, polyurethane seal is sometimes offered by some manufacturers. Vitrified clay pipe that has extra chemical resistance is suitable for sewerage applications. This type of VC pipe may be used even under very corrosive sewage environment. However, the potential for infiltration is great and must be minimised by careful laying procedures on site.


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Vitrified clay pipes are permitted for gravity sewers. The minimum permissible size for public gravity sewer shall not be less than 225mm and service connection shall not be less than 150mm. VC pipes and fittings shall conform to the requirements of MS1061. Pipe strength is classified by the crushing strength (FN) value tested in accordance with BS EN 295-3. The crushing strength for pipe with DN150 shall not be less than 22 kN/m. The crushing strength of the pipe with size ≥ DN 225 is classified by class number. All VC pipes and fittings shall be furnished with spigot-socket flexible joints and rubber ring seals or polyurethane seals. Glazing of VC pipes and fittings are preferred.

2.1.6

Reinforced Concrete Pipe Reinforced concrete (RC) pipe is manufactured in Malaysia in diameters from 150 mm to 3,600 mm. The standard pipe length is 3.05 m. RC pipe is classified according to pipe crushing test load or the three-edge bearing strength which varies with wall thickness and reinforcement. Common reinforced concrete pipes are not resistant to acidic corrosion which occurs in certain septic sewage conditions. The cement used to manufacture concrete pipe shall be factory produced by the cement manufacturer. Pipes can be manufactured using Ordinary Portland Cement, Rapid Hardening Portland Cement, Portland Blast Furnace Cement, Portland Pulverised Fuel Ash Cement and Sulphate Resisting Portland Cement. All these types of cements are corrosion resistance, except Ordinary Portland Cement and Rapid Hardening Portland Cement. To improve the corrosion resistance, high alumina cement mortar lining, PVC lining, PE lining and sacrificial lining Low heat supersulphated cements have also been found in have somebeen testsused. to improve the and corrosion resistance. The inclusion of calcareous or limestone aggregate is another measure found to improve corrosion resistance. To resist corrosion by neutral sulphates occurring in aggressive soils and groundwater, RC pipes are sometimes manufactured using sulphate resistance cement and where not available, portland pulverised fuel ash cement or portland blastfurnace cement shall be used with the approval from relevant authority. RC pipes are permitted for gravity sewers of diameter DN600 and larger. Pipe shall be of Standard Strength or higher as determined from structural design. RC pipes below 1000mm in diameter linings shall consist of either 12mm thick high alumina cement or 38mm thick (as appropriate) sacrificial concrete lining. For RC pipes greater than 1000mm diameters either PVC or HDPE plastic lining or 38mm thick sacrificial concrete lining shall be employed. Other linings may be used if approval from the Commission is obtained. Concrete pipe junctions shall be fixed to the main pipe by the pipe manufacturer and fabricated to clay pipe dimensions. Flexible joints which utilise a rubber ring to join a rebated joint and a spigot to a socket are commonly used and are recommended. Ogee joint (fixed joint) shall be used in conjunction with concrete bedding haunching only. RC pipe when used for pipe jacking purpose, shall be comply with BS 5911. The RC pipes also incorporate rebated joints with joint elastomeric ring seals either integrated in the unit or supplied separately.

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2.1.7

Ductile Iron Pipe Ductile Iron (DI) pipe is manufactured in Malaysia for diameters from 80 mm to 1200 mm. The imported pipe can be up to 2,000 mm. Standard lengths are 6.0 m. DI pipe is classified according to wall thickness. The pressure rating of the pipe increases with an increase in wall thickness. Commonly used pipe strength is class K9 and shall comply with BS EN 598 for working pressure exceeding 6 bars. DI pipe is permitted for force mains and internal pipings of pump stations. DI pipe shall be used for gravity sewers only where it is needed to take the advantages of the strength of ductile iron, e.g. shallow cover sewers subjected to high live loadhigh or sewers of above ground applications. Pipes shall have flexible joints, i.e. spigot-socket rubber seal joints or mechanical joints, except for pump station pipework and valve connections where flange joints shall be used. Ductile iron will undergo corrosion when exposed to certain aggressive groundwaters and conveying certain aggressive water. Therefore, the internal lining protection is required to protect against corrosions. Unless otherwise approved by the Commission, all ductile iron pipes shall have an external coating to be determined by a Qualified Person based on actual soil condition. For internal lining of constant full flowing pipe, ordinary Portland cement shall be used, while high alumina cement mortar or plastic adhesive lining is required for partly full flowing pipes. Buried pipe shall have zinc with bitumen external coating and fittings shall have bitumen external coating. The end surfaces shall include the internal surface of the socket and external surface of the spigot for flexible connection. The finishing layer, which is normally bituminous product, shall cover the whole surface of the applied coating and shall prevent defects such as the loss of adhesion. In addition, the material of the finishing layer shall be compatible with the coating. Unless otherwise approved by the Commission, all fittings and accessories shall be provided with external and internal epoxy coating. Polyethylene sleeving shall be used for all the buried pipe and fittings.

2.1.8

Steel Pipe Steel pipe is manufactured in Malaysia in a wide range of diameters up to 3000 mm and lengths up to 10 m. Pipe joints are normally welded utilising either spigotsocket ends, plain ends or a collar. Flanged and mechanical joints are also available. Steel pipes will undergo corrosion when in contact with aggressive soil and sewage and, thus, require an internal lining and an external coating. Pipe internal linings normally include high alumina cement mortar, coal tar enamel, coal tar epoxy, sulphate resistant cement lining, or bitumen. Pipe external coatings often include coal tar enamel, bitumen enamel or asphalt enamel and glass fibre.


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Steel pipes are permitted only for inverted siphons (depressed sewers) and internal pump station pipework. For force main larger than 700 mm, steel pipe may be used if the approval from the Commission is obtained. The internal and external surfaces of the pipes and fittings shall be coated with thermosetting (epoxy paint or powder or epoxy tar resin) or thermoplastic (polyethylene or polyurethane) material. The type of external protection shall be determined by the Qualified Person based on soil condition. Following the completion of pipe jointing, exposed steel at the joints shall be protected from corrosion by manually applied external tape wrap and internal cement mortar lining. A spigot and socket joint welded both externally and internally shall be used for pipe joints except for pump station pipework and valve connections where flange joints shall be used. Mechanical joints are only permitted for cut pipe lengths, where internal cement mortar lining at joints is not possible and where movement of the pipeline is to be allowed for.

2.1.9

Solid Wall PE Pipe Polyethylene (PE) pipe is resistant to sulphuric acid of concentrations that might be found in septic sewage under the worst conditions. PE solid wall pipe is available locally in diameters up to 1,000 mm and in standard lengths of 6 m and 12 m. This pipe is normally butt fusion jointed. Pipe size of 160mm or less may be flange jointed or electrofusion jointed. PE pipe is classified by pressure rating with static working pressures up to 1.6 MPa. High density PE (HDPE) is used for sewerage applications. Since PE pipes are flexible, the design of the pipe/trench system is more critical than for rigid pipe materials. Compared to rigid pipes, the stability of flexible pipes relies more on the side support of the earth backfill around the pipe. Consequently, in an urban environment, where the side support may be removed during future adjacent construction of underground services, pipe failures could be more frequent. Ground conditions which provide poor pipe side support are unsuitable for flexible PE pipe. Solid wall HDPE pipes are suitable for buried pressure sewer and buried vacuum sewer installations. Butt fusion joints shall be used for PE pipe. uPVC fittings are not permitted for force mains. Solid wall pipe for pressure main application shall be of minimum PE80-PB10. The use of specific strength shall depend on the depth and nature of the soil as confirmed by the Qualified Person. Solid wall pipes for vacuum sewer shall be minimum of PE80-PN8 and at least PN10 for heavy vehicle loading.

2.1.10

Profiled W all P E P ipe A profiled wall pipe is a pipe with a plain inside surface and with a ribbed or corrugated outside surface. The ribs or corrugations are normally either aligned circumferentially or helically. These corrugated or ribbed profiles optimise the pipe ring stiffness to weight ratio. The pipe can be designed with double-wall profile or triple-wall profile.

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Corrugated high density PE pipe is available in Malaysia in a range of size from 100mm to 3000mm nominal diameter and in standard 6m lengths. The standard joint is a flexible spigot-socket joint with rubber seal. Pipes from specific manufacturers in this category may be permitted by the Commission to be used for gravity sewers where special circumstances require the benefits of such pipes.

2.1.11

Glass Reinforced Plastic Pipe Glass reinforced plastic (GRP) pipe is currently required to be imported into Malaysia. There are two principal manufacturing methods for GRP pipes, centrifugal casting and filament winding. The centrifugal casting GRP pipe incorporates silica sand in the wall structure in addition to resin and chopped strand mat glass fibres. The silica sand shall have a maximum particles size of 10 mm. The centrifugal casting GRP pipe shall be according to AS 3751. The filament winding GRP pipe does not normally incorporate sand, which permits centrifugal casting GRP pipe to have a much thicker wall, and thus much higher ring stiffness than the filament winding GRP pipe. The filament winding GRP pipe uses continuous glass fibres wound helically about the pipe. The design of filament winding GRP pipe shall be in accordance with BS 5480. Centrifugal casting GRP pipe is classified by internal pressure resistance for pressure applications and by pipe ring stiffness for non-pressure applications. Centrifugal casting GRP is available up to 10,000 N/m2 stiffness and up to 2.5 MPa static working pressure. Filament winding GRP is available up to 5,000 N/m 2 stiffness and up to 1.6 MPa static working pressure Centrifugal casting GRP pipe is available in sizes from 200 mm to 2,400 mm and standard length of 6 m. The inner surface of the pipe is usually finished with a resin rich lining which is resistance to attack by sulphuric acid that may result from septic sewage. Centrifugal casting GRP pipe has a rubber sealing sleeve joint which is supplied fitted to one end. So jointing is similar to a spigot-socket joint. These pipes can also be supplied with flange joints, sleeve-locking joints and sleeve recessed joints for special applications such as pipe jacking and pipeline towing. Filament winding GRP pipe is available in sizes up to 3,700 mm and standard lengths of 6m and 12m (size dependent). It also has a resin rich inner surface although the thickness of this resin surface layer is often limited by the manufacturing method. Some filament winding GRP pipe manufacturers incorporate corrosion resistant glass fibres. This feature can be essential with this GRP pipe because its resin rich surface (gelcoat) is thinner or, sometimes, removed for fabrication purposes. Filament winding GRP pipe currently being offered can be jointed using a sleeve and two rubber O rings. Filament winding GRP pipe does not have a smooth outer surface like centrifugal casting GRP pipe. Machining may be required for the outer surface where rubber sealing rings are used. Flange joints and mechanical couplings are also available for special applications.


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GRP pipe is classified as a flexible pipe. It requires sufficient side support to retain its structural integrity in cross-section in the same way as uPVC and PE pipe. GRP pipe has lower strain limits than uPVC and PE pipes since it is made of thermoset resin, which is brittle compared to thermoplastic material. Due to its inherent structure, GRP pipe has a much higher modulus of elasticity than uPVC and PE pipe. Thus, it may have a much thinner wall than uPVC and PE pipes to achieve equivalent ring stiffness. GRP pipe is generally available in higher stiffness than, uPVC and PE pipe. Approval for the use of GRP pipe shall be sought from the Director General for each project intending its use. GRP pipes are permitted for gravity and pressure sewers. For gravity sewers, GRP pipes are only permitted for sizes of 600mm nominal diameter and larger where no fittings are required. The minimum pipe stiffness shall be SN 5000 with the appropriate stiffness determined in accordance with structural design to AS 2566. For pressure sewers, fittings must only be of ductile iron meeting the coating, lining and other requirements.

2.1.12

Acrylonitrile Butadiene Styrene Pipe Acrylonitrile butadiene styrene (ABS) pipe is a thermoplastic pipe. It is manufactured in Malaysia in diameters up to 630 mm. ABS pipe is classified by internal pressure resistance. It comes in various static working pressure ratings up to 1.5 MPa. The most common jointing method is by solvent cementing. The cementing jointing process is more complex than the jointing process of uPVC pipe. A spigot/socket rubber ring joint is generally not available. Because of the care required to make a solvent cement joint, particularly in larger diameters, the jointing of ABS pipe requires special trainings. ABS, like uPVC and PE, is resistant to corrosion in the most corrosive sewage environment that could occur. ABS is used in a range of applications requiring pressure pipe. Because of its excellent resistance to abrasion and UV degradation, ABS has found use in industrial and mining applications and also in treatment plants for sewage and water. ABS pipes may be permitted for force mains under special circumstances which require the benefits of such pipes. If used, the approval of the Commission is required. ABS pipes may be permitted for use in buried forced mains and buried interconnecting pipe-works within pump stations.

2.1.13

Sewer Design - G eneral R equirements The design of a sewerage system shall generally be in accordance with the principles set out in this guideline. Additional requirements in the Malaysian Standard MS 1228:1991 Code of Practice for Design and Installation of Sewerage System shall also be referred to in design. The sewerage system shall be suitably designed to carry all sewage flows including sullage to the approved disposal point. Unauthorised connections of surface waters or excessive infiltration to the sewerage system are not permitted.

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Unless otherwise agreed by the Commission, all sewers shall be sited in public road reserve so that access can be gained for maintenance purposes. Under special circumstances where the sewer cannot be sited in public road reserve then vehicular access of at least 3 m in width and road bearing capacity of not less than 5 tonne shall be provided. A checklist for sewer reticulation design is given in the Malaysian Sewerage Industry Guidelines, Volume II.

2.1.14

Flow Rate Estimations Few principal considerations when selecting the diameter and gradient of a sewer are: i)

to cater for peak flow

ii)

to ensure that there will be a sufficient velocity during each day to sufficiently cleanse the sewer of slime and sediment

iii)

to limit the velocity to avoid scouring of sewers

a)

Average Flow:

The volume of sewage that needs to be treated per day is based on an assumed contribution per person of 225 litres. Another assumption is made as to the contribution from various types of premises where the contribution from each premise type is defined in terms of an equivalent population. The recommended minimum population equivalent values are given in Table B.1.

b)

Peak Flow:

The flow used to determine the diameter and gradient of the pipeline is the peak flow. Peak flow is the most severe flow that could occur on any day when considering daily flow fluctuations and infiltrations. The peak flow is derived from the average flow by applying a peak factor for daily flow fluctuations. The peak factor shall be estimated from the following formula:

Peak Factor = 4.7 (PE/1000)

-0.11

Where PE = assumed population equivalent

c)

Infiltration:

Infiltration is the amount of groundwater that enters sewers through damage in the network such as cracked pipes, leaking joint seals, leaky manhole walls, etc. There are many variables affecting infiltration such as quality of workmanship, joint types, pipe materials, height of water table above pipeline, soil type, etc. The peak factor above has included the contribution of infiltrations. The maximum allowable infiltration rate shall be 50 litre / ( mm diameter.km of sewer length.day ).


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2.1.15

Sewer Cleansing Velocities The principal accumulants in sewers are slimes and sediments. The hydraulic requirements for cleansing the sediments of sewer differ from those required for cleansing the slimes of sewer.

a)

Sediment Cleansing:

For the removal of sediments, the traditional design approach has been to set a minimum velocity to be achieved at least once daily. Minimum velocity values at full bore of diameters 0.8 m/sec are commonly it has been found larger pipe require higher specified. velocity toHowever, cleanse the sediment. Thisthat is mainly due to higher sediment depths in large diameter pipes The movement of sediment is mainly a function of shearing stress needed to dislodge sediment off the pipe wall. Similarly, shear stress is a function of pipe diameter. Also, the type of sediment (i.e. grain size, specific gravity, cohesiveness) also influences the movement of sediment and, thus, the amount of required shear stress. For design purposes however, only a single sediment type needs to be assumed.

b)

Slime Cleansing:

The removal of slime depends on the stress needed to shear sections of slime from each other or from the pipe wall. However, the shear stress required to remove slimes is not a function of pipe diameter. The necessary shear stress depends on the thickness of slime to be removed and the pipe material. The degree of removal of slimes in any pipe material varies with the sewage velocity. Removal of large portion of slimes requires high sewage velocities. It has been found that 85% or more of the sulphide producing slimes are removed when the grade of the sewer is 2.5 times of that for sediment cleansing. In many instances, it may not be practical to design a sewer to achieve such velocities due to the excessive cost of constructing such a deep and steep sewer. Although increasing the velocity up to the critical velocity will increase the amount of slime being sloughed off, the rate of sulphide production remains substantially unaffected by the thinner slime layer. Therefore, the selection of steep gradient to achieve velocities for full slime stripping is not a design requirement.

2.1.16

Pipe R oughness Except for very high velocities, slime will always be present, which will increase the pipe roughness. Abrasion by sediments will also impart a permanent increase in roughness. Pipeline roughness decreases as the velocity increases. However, there dataattosmall accurately determine the pipeline roughness for a wide range isofinsufficient velocities or incremental changes in velocity. In addition, the velocity of the sewage flow varies due to the factors such as daily fluctuations, different type of catchment, different stage of catchment maturity, etc. Therefore, it is not possible to select the pipe roughness with great accuracy. Conservative roughness values as given in Table 2.1 shall be referred to when determining sewer discharge capacity.

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Table 2.1a

Normal Pipe Roughness for Gravity Sewer Roughness, ks (mm) New Old 0.06 1.5 0.15 3.0 0.06 0.6

Pipe Material Vitrified Clay Concrete: Plastic

Old and new roughness values shall be used to determine the sewer cleansing and maximum design velocities respectively.

Table 2.1b Normal Pipe Rough ness for For ce Mains for All Pipe Materials Mean Velocity, V (m/s) 0.8 ≤ V ≤ 1.5 1.5 ≤ V ≤ 2.0 V ≥ 2.0

2.1.17

Roughness, ks (mm) 0.6 0.3 0.15

Design of Gravity Sewer Unless special arrangements have been agreed for the structural protection of pipes, the minimum depth of soil cover over the sewer shall be 1.2 m. Sewers are not to be constructed under buildings. The minimum size of public gravity sewers shall be 225 mm in diameter. The minimum size of domestic connections to the public sewer shall be 150 mm in diameter. The maximum design velocity at peak flow shall not be more than 4.0 m/s. The design shall be based on the worst case scenario. The selection of the gravity sewer diameter and gradient to cope with the peak flow shall be based on the following equations:

1.

Colebrook - W hite Equation V

= −2

(2 g D S

log

⎛ ks ⎜ ⎜ 3.7 D + ⎝

2.51ν D

⎞ ⎟

2gDS ⎟⎠

where V S ν

D g ks


= = = = = =

Volume 3

velocity hydraulicgradient(m/m) kinematic viscosity of water (m 2 / sec) internaldiameter(m) 2 accelerationduetogravity(m/sec ) roughness coefficient (m)

21


Typical ks values for various types of sewer pipes are presented in Table 2.2 below:

Table 2.2

Typical Roughness Coefficient, k

Material Concrete Cast iron Asphalted cast iron Ductile iron

2.

s

Roughness Coefficient, ks (mm) 0.3 to 3 0.26 0.12 0.046

Manning Equations

V

=

R

2/3

S n

1/ 2

where V S R n

= = = =

velocity (m/sec) hydraulicgradient hydraulic radius Manningcoefficient

Typical n values for various types of sewer pipes are presented in Table 2.3 below:

Table 2.3

Typical Manning Coefficient, n Manning Coefficient, n Good Condition Bad Condition 0.012 0.015 0.011 0.013 0.012 0.015 0.010 0.017 0.012 0.016

Material

Uncoated cast-iron Coated cast iron Ductile iron Vitrified clay pipe Concrete

3.

Hazen - Williams Equations V = 0.849 C R

0.63

S 0.54

where V S R C

22

= = = =

velocity (m/sec) hydraulicgradient hydraulic radius Hazen-Williamscoefficient

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Typical C values for various types of sewer pipes are presented in Table 2.4 below:

Table 2 .4

Typical H azen-Williams C oefficient, C

Material Top quality pipes, straight and smooth Smooth masonry Vitrified clay

Hazen-Williams Coefficient, C 130 to 140

Old cast iron Old cast iron in bad condition

100 60 to 80

120 110

Colebrook-White Equation has been deemed to give the most accurate results. However, the other equations, such as Hazen-Williams Equation and Manning Equation are easier to use and may be used too. Various design charts and tables have been developed elsewhere to aid the manual computations.

2.1.18

Design of Force Mains The minimum diameter of force mains (also known as rising mains) shall be 100 mm diameter. There shall be no reduction in force main diameter with distance downstream. All bends on force mains shall be securely anchored to resist lateral thrusts and subsequent joint movements. Air release valves and washouts shall be provided at appropriate locations along the longitudinal profile. For long and undulating force mains, hydraulic pressure transient analyses may be required to ensure that the force main can cope with water hammer pressures. Retention times in force mains must not exceed 2 hours without special precautions to mitigate septicity. All force main shall be designed to withstand at least 1.5 times the working pressure. Approval from the Commission is required if any force main is to be designed to withstand pressure less than the pressure stated above. Where retention times in the force mains exceed two hours and where concrete pipe are laid downstream of the force mains, an induct vent shall be provided at manholes receiving pumping discharges. Friction losses are normally calculated using either Darcy - Weisbach (ColebrookWhite) Equation or Hazen-Williams Equations. The forms of the equations are different from the equations used to design gravity sewers. The equations are listed below:


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23


1.

Darcy-Weisbach E quation

h

=

2

LV

2 gD

where hf f

= =

Friction loss Coefficient of friction

V g D L

= = = =

Velocity inthepipe Acceleration duetogravity Equivalentdiameterofthepipe Length of pipe

The value of f is known to depend on the Reynolds number, Re, pipe roughness, k s, and pipe diameter, D, through the Colebrook-White equation as follows: 1 = sqrt (f)

-2log k

2.51 +

s

3.7D

Re sqrt ( f)

The Reynolds number is defined as follows: Re

=

VD v -6

where v is the kinematic viscosity of the fluid, typically equal to 1 x 10 sewage.

2

m /s for

The above equations together with the Moody Diagram are used to determine the coefficient of friction, f.

2.

Hazen-Williams Equation

hf

=

6.82

⎛V ⎞ ⎜ ⎟ ⎝ C⎠

1.85

L D

1167 .

where hf C

= =

Friction loss Hazen-WilliamCoefficient(refertoTable2.4)

V L D

= = =

Velocityinthepipe Length of pipe Equivalentdiameterofthepipe

Force mains shall be designed to handle the full range of flows from present minimum to future peak.

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The design velocity shall fall within the range of 0.8 to 3.0m/sec over the full range of design flows. The hydraulic resistance of force main fittings and bends shall be included in the hydraulic design.

2.1.19

Vacuum Sewerage System The design requirements of this Guidelines are the minimum requirements, and do not constitute in themselves a comprehensive design guide sufficient to ensure a correctly functioning system. system must be where individually designed, based are on the design parameters of theEvery system employed; proprietary systems employed, it shall be designed in compliance with the requirements of system manufacturers.

2.1.19.1 General Specification of a vacuum sewage collection system shall only be considered where the life-cycle costs of a conventional gravity sewage collection system are clearly shown to be higher. This Guidelines assumes that all sewage transportation modes have been identified, their respective feasibilities evaluated against technical, environmental, financial, economic and other relevant criteria over the design life of the asset and that vacuum sewage collection system has been confirmed as the best option. The Commission may request for net present value (NPV) calculations for all options prior to approving construction of a vacuum sewage collection system.

a)

Application of vacuum sewage collection system

Consideration shall be given to the use of the vacuum system in one or more of the following circumstances: i. ii. iii. iv. v. vi.

b)

Flat or undulating terrain; Obstacles to the sewer route eg utility services, waterways; Poor ground subsurface eg high ground water table, rocky terrains; Isolated, low density communities; Where it is necessary to minimise the impact of construction work; Where it is necessary to minimise the environmental impact.

Unit Processes

Typical unit processes for a vacuum sewage collection system is shown in typical drawing in Appendix A. The unit processes shall comprise of, but not limited to, the followings:i.

Collection chamber for housing vacuum interface valve and also forming a sump from which collected sewage is evacuated;

ii.

A vacuum sewer network for the transport of sewage collected in the collection chambers to a central vacuum station;


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25


iii.

A central vacuum station where the vacuum pressure is generated which allows the sewage to be collected and forwarded to a receiving gravity sewer manhole or a sewage treatment plant.

c)

Description of System

i)

Collection chamber and vacuum pipeline

When the volume of sewage draining into a collection chamber reaches a predetermined level between in the sump, the normally interface forces valve opens. The differential pressure the vacuum sewer closed and atmosphere the sewage from the collection chamber into the vacuum sewer via a crossover pipe. Typical crossover pipe connection is shown in typical drawings in Appendix A. After the sump is emptied, the valve closes. Air is admitted simultaneously with, or after, the admittance of the sewage. The sewage is driven along the sewer until frictional and gravitational forces eventually bring it to rest in the lower section of the pipe profiles. The characteristics of the vacuum sewerage system ensure that peak discharges into the sewer are rapidly attenuated. The vacuum sewer discharges into the vacuum vessel at the vacuum station. The vacuum is maintained, by vacuum pumps, at a predetermined level. The sewage is generally pumped from the vacuum station by sewage discharge pumps.

ii )

Vacuum station

The vacuum station is similar to a conventional pumping station with the addition of vacuum pumpsinand a closedA. vacuum vessel. Typical vacuum is shown typical drawings Appendix The level of the sewage in thestation vacuum vessel in is monitored by a level detection probe which activates the sewage discharge pumps. If the sewage rises too high in the vessel then a high level detection probe stops and locks out the vacuum pumps to prevent the flow of sewage into the vacuum pumps. The vacuum in the vacuum vessel is maintained within the operational range by pressure switches.

d)

Warranty of System Performance

Since the vacuum system involves proprietary design and equipment, specialist system designers shall be accountable to the performance of the entire vacuum system including both design and construction aspects. The specialist system designers shall also specify clearly the specific maintenance and operational requirements of the system. /

2.1.19.2 Collection Chamber a)

General design requirement

Collection chambers shall have sufficient capacity to store sewage discharged from all connected properties for at least 6 hours in the event of a valve failure or similar emergency, which is sufficient to cover the IWK’s emergency response time.

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The overflow storage time shall be based on the ultimate sewage design flow that will enter the collection chamber. The volume that can be used for emergency storage shall be the volume contained in the collection chamber from the base of the collection chamber up to the lowest ground level at any point served by the chamber as well as the volume contained in the gravity lateral sewers entering the collection chamber. Separate chambers shall be provided to serve properties at different elevations where there is a likelihood of sewage from one property flooding another property. The chamber shall resist external forces and internal water pressure. The preferred material of construction for collection chambers is pre-cast concrete. The two sections (the valve compartment and the collection sump) may be mounted vertically one on top of the other as shown in typical drawings in Appendix A. The diameter of the sections may be as small as 1200mm or as large as 1500mm. The collection sump requires a benching section that allows a scouring action from the sewage as it enters the suction pipe, thereby rendering the sump self-cleansing. The internal surfaces of the sump shall be both strong as well as resistant to corrosive attacks from the collected sewage. Where the interface valve is situated over the collection sump, a working platform shall be provided for allowing maintenance engineers to stand on when carrying out scheduled maintenance to the interface valve. The sump shall be sufficiently vented to allow the intake of air without causing a noise nuisance and to ensure that the operation of the vacuum system does not unseal the water traps on the gravity drainage system.

b)

Number of properties connected

The location of each collection chamber and the number of properties connected to each collection chamber shall be specified in the Design Drawings / Calculations. Sewage flow from the maximum number of existing or future properties that are proposed to be connected to a collection chamber shall be quantified, and the retention time of the collection chamber can be then established. The retention shall exceed 6 hrs. /

c)

Maximum flows to collection chambers

The maximum sewer design flow to a single vacuum interface valve collection chamber shall not exceed 0.25 lit/s. Where single point flows in excess of 0.25 lit/s occur, multiple vacuum interface valves shall inbeAppendix installed.A.Typical multi-valve collection chamber is shown in typical drawings

d)

Breather pipes

Some vacuum interface valves inhale and exhale air during their operation. This is accomplished through a screened air pipe known as a "breather".


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While breather bells are generally mounted inside the collection chamber, it may be necessary to mount them externally. Each breather pipe shall be fitted inside the "breather bell" located at the top of the collection chamber in an accessible location to allow their removal for maintenance purposes.

e)

Covers and frames

Collection chamber covers shall provide an access opening of at least 600 mm diameter. and frames shall be installed in accordance with the requirements stipulated Covers in Clause 2.3.

2.1.19.3 Vacuum In terface Val ves a)

General

The interface valve shall fail safe in the closed position and shall prevent backflows from the crossover pipes to the collection sump. When the valve is open, the flow path shall not be obstructed by the valve mechanism. The valve shall evacuate at least the batch volume each time it cycles. Valves installed in the sump shall be capable of operating when submerged provided that the breather pipe is not submerged. The valve shall be installed in the collection chamber using demountable, re-useable “ No Hub” couplings suitable for vacuum service.

b)

Level sensor

The valve shall be equipped with a sensor to determine the level of sewage in the collection sump; this sensor shall be designed to be fouling resistant. Level sensor pipes shall not be less than DN/ID 45.

c)

Interface valve controller

The controller shall open the valve only if there is a minimum partial vacuum of 0.2bar below atmospheric available and shall maintain the valve fully open until at least the batch volume has been evacuated. If the design provides for the introduction of air after the sewage has been evacuated, the controller shall maintain the valve open for a further period. The controller shall be adjustable so that a range of air to sewage ratios can be obtained. Controllers installed in sumps shall be capable of operating when submerged.

d)

Explosion proof

The valve mechanism and controller shall be explosion proof if exposed to potentially explosive atmosphere.

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e)

Life of valves and membranes

Every interface unit, comprising the interface valve, controller and sensor shall be expected to last in excess of 25 years. Manufacturers shall clearly specify scheduled maintenance, thus allowing the operators to keep the interface units in tip-top conditions at all times.

2.1.19.4 Vacuum Sewer Design a)

General

For a completely flat area, the length of a single sewer branch shall not be more than 3km. However, the maximum limit of the pipe length would vary according to the gradient achievable in that line. Specialist system designer shall provide a detailed hydraulic calculation for the vacuum sewer network. Vacuum main routes shall be selected to: i. ii. iii. iv.

b)

Minimise lift; Minimise length; Equalise flows on each vacuum main; Provide adequate access for operation and maintenance.

Sewer depth

Vacuum sewers, branch sewers and crossover pipe connections from the collection chambers, shall have a minimum cover of 0.9 m to withstand the stresses arising from traffic loads. When sewers are not buried, they shall be protected from extremes of temperature, ultra-violet radiation and possibility of vandalisms. When sewers are suspended underside walkways or bridges, they shall be rigidly supported so there is no visible sagging between supports. Supports shall withstand all static and specified dynamic conditions of loading to which the piping and associated equipment may be subjected. As a minimum, consideration shall be given to the following conditions: i. ii. iii.

c)

Weights of pipe, valves, fittings, pipe protection materials, and medium in the pipe; Reaction forces due to the operation of isolation valves; Wind loadings on outdoor piping.

Sewer profiles

Pipeline profiles shall be self cleansing and prevent the accumulation of solids. Typical pipeline profiles are shown in typical drawings in Appendix A. For crossover pipes, the minimum distance between lifts shall be 1.5 m. Vacuum sewers shall have a minimum gradient of 1 in 500. Where the ground has a gradient of 1 in 500 or more in the direction of flow, the vacuum sewer may be laid parallel to the surface as shown in typical drawings in Appendix A.


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i)

Design tolerances

The chainage and invert levels of the pipeline(s) shall be determined to the following levels of design accuracy and specified in the Design Drawings:

• •

Sewer chainage to the nearest 0.5 m. Sewer invert levels to the nearest 0.01 m.

ii)

Lift design

To provide for efficient vacuum transport to sewer extremities, the size of individual lifts shall be kept as small as possible. Many small lifts are preferable to one large lift. The change in invert at each lift shall not exceed 1.5 m. For vacuum sewers, the minimum distances between lifts shall be 6 m.

iii)

Crossover pipe connection

Crossover pipe shall initially fall away from the interface valve and shall connect into the top sector of the vacuum sewer contained within the angle of ± 60° about the vertical axis as shown in Standard Drawing – Figure Vac7.

iv)

Branch connections

All branch connections to vacuum sewers shall be by a Y-junction connected to the sewer above the horizontal axis as shown in Standard Drawing – Figure Vac8. In plan, the angle of the Y-junction shall ensure that flow towards the vacuum station is generated and backflows are minimised. No connection shall be made within 3m of a lift.

v)

Water-logging

The profile shall ameliorate water-logging at any change in gradient even when a prolonged power failure occurs (both TNB supply and standby genset fail), and the vacuum interface valves continue to operate and admit sewage until the vacuum level reduced to the point when they will no longer open. When power is again available, the system shall be capable of recovering to normal operation without intervention by an operator.

d)

Pipework and Fittings for Vacuum Sewers

The recommended material from which to construct vacuum sewers is PE 80 SDR 13.6 rated polyethylene pipe. Pipe fittings shall be PE 100 SDR 13.6. Pipes shall be UV stabilised with carbon black which shall give the pipe a black colour throughout. Four evenly spaced brown stripes shall be incorporated, thus readily identifying that the pipe is transporting sewage. The polyethylene pipe is selected because it is both structurally strong and compatible with potentially chemically aggressive and abrasive flows in the sewage.

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i)

Pipe size

The suction pipe DN/ID shall not be greater than the DN/ID of the interface valve. The minimum diameter of crossover pipe shall be DN/ID 50 and shall be greater than the DN/ID of the suction pipe. Vacuum sewer shall have a minimum diameter of DN/ID 80.

ii)

Jointing of PE pipes and fittings

PE pipes and fittings less than DN 160 shall be jointed using electrofusion fittings. Pipes and fittings DN 160 and larger shall be jointed with electrofusion fittings or butt fusion welding.

iii)

Warning system

To act as a warning to an excavation possibly carried out at a later date, the use of a marker tape laid 300mm on top of the pipe is recommended. This shall be a 150mm wide polyethylene and printed with a descriptive warning of the pipework below.

e)

Isolation valve

The isolation valve clear opening shall be not less than the DN/ID of the pipe, and be capable of sustaining a vacuum pressure of -0.8 bar(g). Isolation valves shall be resilient seated gate valves with the body, bonnet, gate and bridge fabricated from ductile or cast iron. The stem shall be stainless steel, and the gate shall be encapsulated with EPDM. End connections to the valves shall be flanged.

i)

Isolation valve installation

Each isolation valve shall be located in a chamber, which shall contain a dismantling arrangement for replacement of the isolation valve if needed. When isolation valves are buried, they shall have extension spindles and surface boxes.

ii)

Isolation valve location

Means of isolating lengths of vacuum sewer to permit repairs or to locate faults shall be provided at distances of not more than 500 m and on branch sewers longer than 200 m.

2.1.19.5 Vacuum Station Design a)

General

It is desirable to have the vacuum station located as centrally as possible within the sewer network. This lends itself to a system with multi-branches hence giving added operating and design flexibility. Ideally, the design capacity of a singlevessel vacuum station shall not exceed a population equivalent of 8,000 persons. A


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dual-vessel station, or more than a single-vessel station that is completely isolated, shall be provided when the population equivalent exceeds 8,000 persons.

b)

Vacuum station layout

A typical vacuum station layout is shown in typical drawings in Appendix A. The vacuum station shall be divided into two main areas, an above ground plant room and a below ground dry well. The floor level of the dry well shall be designed to suit the invert levels of the incoming sewers, the vacuum vessel diameter and the dimensions of the selected sewage discharge pumps. The vacuum vessel, the sewage discharge pumps, valves and pipework associated with the sewage discharge pumps and a small sump to collect washdown water shall be located in the dry well. The plant room shall contain the vacuum pumps, control panel, standby diesel generator, vacuum pressure gauges, and moisture trap.

c)

Vacuum vessel

Vacuum vessels shall be designed to meet the requirements of ASME Section VIII Division 1 – 2004 Edition. The vessel shell shall be constructed from mild steel or any other approved material. Sewer inlets shall be provided with short radius elbows inside the vessel to direct the vessel sewagewalls. inflow away from the sewage discharge pump suction connections and the A vacuum vessel may have up to five (5). incoming vacuum sewers connected directly to the vessel. No inlet pipes shall be connected below the system emergency stop level. Sewage discharge pump suction connections shall be provided at the invert of the vacuum vessel. The vacuum vessel shall be fitted with an externally mounted sight glass which is suitable for operation in a vacuum and is easily removed for cleaning without decommissioning the vessel. The vacuum vessel shall be provided with a DN 600 access opening, and the cover shall be provided with a lifting eye. Wherever possible, the opening is preferably positioned on the top of the vessel in order to minimise the size of the structure necessary to house the vessel, this conserves valuable resource, reduces the footprint of the building, and thus allows adjacent residences to enjoy more buffer spaces. During the inspection or maintenance works, safe entry procedures shall be adhered to, according to the Department of Occupational Safety and Health (DOSH) codes of laws, by trained certificated operator, and that the vessel is decommissioned, with the access opening removed and discharge pipeworks at the two (2) draw-off points dismantled, and a forced air ventilation is applied. It is important to ensure that the system would operate continuously in the face of having the vacuum vessel temporarily out of service during an interval inspection.

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C o n cl u d


The incoming sewage shall manually be bypassed to a mobile vacuum tanker via a flexible ribbed pipe. The pipe is of an adequate length to reach the bypass valves safely. Typical bypass valve arrangement is shown in typical drawings in Appendix A.

d)

Moisture trap

When mechanical vane vacuum pumps are selected, moisture trap shall be provided for the vacuum pumps. Baffles or moisture removing material shall be fitted inside each vessel to assist with moisture removal.

e)

Vacuum pumps

Vacuum pump capacity (Qvp) shall be rated. The selection of appropriate size of vacuum pump is determined by the following four factors:-

• • • •

The peak flow of the sewage to be collected; The length of the longest single sewer within the sewer network; The total volume of the sewer pipework within the network; Air to liquid ratio employed (ratio not less than 3).

i)

Evacuation time

When the vacuum pumps, collection chamber and vacuum vessel have been sized, system evacuation time for an operating range of – 0.55 bar(g) to –0.65 bar(g) shall be calculated using:

⎡⎛ 2 ⎞ ⎤ ⎢⎜ 3 ⎟Vvs + (Vvv − Vo ) + Vmt ⎥ × 60 ⎣⎝ ⎠ ⎦ t= Qvp

Where, t = system evacuation time, minutes Vvs = volume of vacuum sewers, m³ Vvv = volume of vacuum vessel, m³ Vo = operating volume of vacuum vessel, m³ Vmt = moisture trap volume (if fitted), m³ Qvp = vacuum pump capacity, m³/hr NOTE: In normal operation it is assumed that the vacuum sewers will be

approximately 1/3 liquid filled. The system evacuation time, which is defined as the time period between the vacuum pump start and stop, shall be between 2 and 5 minutes. ii) Selection of vacuum pumps

Vacuum pumps shall have sufficient capacity to serve the system. A minimum of two vacuum pumps of equal capacity shall be installed such that one pump can be


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removed for maintenance without loss of system capacity. Vacuum pumps, where used, shall be suitable for both continuous operation and for a minimum of 6 starts per hour.

iii)

Vacuum pipework

ABS pipes and fittings shall be used for interconnecting pipework between the vacuum pumps and the vacuum vessel within vacuum stations. Pipework shall be fully supported.

f)

Sewage discharge pumps

Two sewage discharge pumps of equal capacity are recommended for use in a vacuum station. Each pump shall be sized to discharge sewage at a rate at least equal to the calculated design peak flow for the vacuum system. Sewage discharge pumps shall be capable of pumping unscreened sewage and suitable for immersed operation in the event of the vacuum station dry well flooded. In normal operation the dry well will not contain water. Pumps may have a vertical or horizontal configuration. Sewage discharge pumps shall be suitable for a minimum of 6 starts per hour. Equalizing lines connecting the discharge side of the centrifugal sewage discharge pumps to the vacuum vessel shall be installed if required to prevent cavitation or to ensure that the pump inlet is always flooded. Sewage discharge pumps shall be fitted with isolation valves to allow removal of the pump without disrupting the system operation. Discharge pipework for each pump shall be fitted with a non-return valve and a resilient seated gate valve on the discharge side. Where the discharge pipework is manifold, the final discharge pipe shall also be fitted with a non return valve. The valves shall be able to be operated from the vacuum station floor.

g)

Vacuum gauges

150mm vacuum gauges calibrated to read 0 to -1 bar to an accuracy of ±2% shall be fitted to the vacuum vessel and each incoming vacuum sewer. Vacuum gauges shall also have bottom outlets fitted with lever-operated ball valves. All gauge diaphragms shall be suitable for use with sewage gases. The gauges indicate the vacuum pressure within each sewer and enable pressures within the sewer network to be monitored.

h)

Fire-fighting system

Fire-fighting system using carbon dioxide at the genset / fuel room shall be provided at every vacuum station in accordance with Bomba’s requirements.

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i)

Odour control

Effective odour control system shall be provided to treat air vents from a vacuum station to prevent malodour impacts being imposed on downstream residential areas. Biofilters shall be used to remove the odours from the vacuum pump exhaust gases containing toxic and odorous compounds by passing the gases through a natural biologically active filter medium.

j)

Noise control

Vacuum station shall be acoustically designed and fitted with noise control measures, as required to control noise to levels that comply with local council’s regulations.

k)

Controls and Telemetry

i)

Vacuum level control

Vacuum levels in the vacuum vessel shall be controlled by vacuum switches with an operating range of 0 to -1 bar(g). Their purpose is to control the operation of the vacuum pumps and to maintain the vacuum within the vessel inside the operating range. A minimum of four vacuum switches shall be provided to operate the duty and assist pumps, and to provide a high and a low vacuum alarms.

ii) Level control The level detection probes shall be mounted on the vacuum vessel. Their purpose is to control the operation of the sewage discharge pumps and to maintain the sewage within the vessel inside the operating range. Probes shall be manufactured in one length without any screw joints along their length. Any form of float switch, including magnetic and ultrasonic types shall not be permitted. The level control system shall respond to the following sewage levels in the vacuum vessel: Emergency stop level

- stops vacuum generation; - sewage discharge pump operates;

Start level

- starts sewage discharge pump;

Stop level

- stops sewage discharge pump;

iii) Vacuum / sewage discharge pump control The controls shall permit the selection of duty, duty assist (where provided) and standby vacuum pumps and sewage discharge pumps and shall provide for the automatic introduction of the standby units in the event of failure.


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The electrical controls shall allow sequential operation of all pumps so that running times are equalised. The standby pump shall automatically cut-in should the duty pump fail.

iv) Valve monitoring system / station telemetry Valve monitoring and station telemetry systems are optional, but, shall be implemented for larger schemes comprising more than 50 interface valves. The open and closed status of interface valves shall easily be detected by the use of ainstall remote control viatoinfrared/radio signals. Alternatively, system suppliers may a signal cable relay this information to a display panel within the vacuum station. All monitoring components installed at the collection chambers shall be robust and suitable for use in sewerage application. Large schemes shall also include a telemetry section with volt-free contacts for each condition/alarm of the station equipment as shown in Table 2.5

Table 2.5 Condition/alarm of the st ation equipment DESCRIPTIONS Stationpower Vacuumpumppower Sewage discharge pump power Vacuumpumpoverload Sewage discharge pump overload Vacuum level Vacuum level Sewage level Intruderalarm Firealarm

INPUT / OUTPUT Failed OK / Isolated/OK Isolated / OK Tripped/OK Tripped / OK Low OK / High OK / High OK / Activated/OK Activated OK /

v) Emergency power generation A back-up diesel generator shall be provided to adequately run the station in the event of an electric power disruption. The generator shall be capable of providing 120% of power for at least one vacuum pump and one sewage discharge pump and other necessary equipment.

2.1.20

Computerised Sewer Designs Manual computations for the hydraulic design of a sewer network can be avoided for many aspects using proprietary computer software or in-house computer programs. However, there are many variations possible for the different aspects of hydraulic design, i.e. flow contributions from different sources, quantity of infiltration, quantity of inflow, sediment cleansing requirements, pipeline roughness coefficients, etc. It is therefore necessary that the computer software or programs adopt the hydraulic design requirements as detailed in this guideline. Some proprietary softwares may not permit certain adaptations required to conform to the hydraulic design requirements given in this guideline. As such, these software would be unsuitable.

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2.1.21

Design of I nverted Siphon Inverted siphons are introduced along a gravity sewer line in order to pass under an obstacle (e.g. railway line, stream, culvert, etc). An alternative to an inverted siphon for bypassing obstacles is a pump station. But such an option may be economically not viable. The profile of an inverted siphon encourages solids settlement and accumulation and therefore they require more frequent cleaning. They must be avoided as much as practicable. Inverted siphon shall consist of at least two or more parallel pipelines (or barrels). The minimum pipe size for of aconvenient barrel shall be 225mm, and shall be provided with necessary appurtenances flushing and maintenance. There will be an inlet chamber designed to divide the flow among the pipes by allowing each pipe to come into operation in succession and an outlet chamber designed to prevent eddies from carrying solids and sediments back into the siphons. Longer siphons shall be provided with hatch box with access for maintenance and cleaning. These siphons shall have independent washout facilities. The manholes shall have adequate clearance for rodding. In general sufficient head shall be provided and pipe sizes selected to secure flow velocities of at least 0.9m/sec for average flow. The inlet and outlet shall be arranged so that the normal flow is diverted to one barrel, and so that either may out of service for cleaning. Its choice should be taken into consideration the operational and maintenance aspect of siphons. The siphons shall not have sharp bends, either vertical or horizontal. The horizontal leg of the siphon shall have a negative gradient of 8 ° to 10°, whilst the rising leg shall be limited to 30° to 45° should space permitting. There shall be no change in pipe diameter along the length of the barrel. Pipes and pipe joints used for siphons shall be designed at the appropriate pressure rating.

2.1.22

Structural Design of Sewers The structural design of a buried sewer can be divided into the following two categories: a)

rigid pipe

b)

flexible pipe

All two structural designs shall take account of how the sewer is supported to determine the loading which the sewer can safely withstand. The structural design of a buried sewer normally considers only the structural integrity of the pipe cross section. Although not as critical as the structural integrity of the pipe cross section, the considerations for the ground conditions and sewer not be installation omitted. practices that will affect the longitudinal structural integrity shall There are many design approaches for each of the two structural design categories. However, there are only minor alterations among these different approaches. Some design approaches tend to give a more favourable prediction of performance for a particular pipe material than other approaches. The use of standard design approaches given in this guideline will prevent the selection of a particular design


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approach purely to favour one material over another. Also, the following recommendations are only meant for general design aspects. Any design aspects that are not covered by this guideline, the designer shall refer to BS EN 752 or any other standards deemed appropriate by the Commission.

a)

Rigid Pipe Structural Design:

Pipes which are classified as rigid are: i. ii.

vitrified clay pipe reinforced concrete pipe

The failure of a rigid pipe normally occurs by pipe fracture. Thus, for structural performance, the determination of the pipe ring crushing strength/load is required. This strength is determined using a three point loading test as described in the respective Malaysian standards for the above pipes. Both VC pipe and RC pipe can be made to achieve different ring strengths as defined in the standards. When a buried rigid pipe is supported, the load which the pipe can safely withstand is higher than the load which caused failure in the three point loading test. The improvement in load resistance provided by different pipe support designs is defined by the bedding factor. Where the sewer is supported on granular material, such as crushed rock, the bedding factor becomes a function of the density of the granular material and the height to which the granular material is placed above the sewer. By varying the pipe ring strength and the pipe support, different load resistance can be achieved. The pipe support designs permitted by this guideline are limited to those in typical beddings in Appendix A. They include the following: i. granular bedding/ Crusher rock ii. concrete cradle iii. concrete arch (with granular bedding) iv. concrete surround Granular bedding design shall be adopted wherever possible. Concrete support or arch designs should be avoided. This is due to the difficulty in achieving full contact of the concrete support with the pipe ring. A higher strength pipe in combination with crushed rock support is preferred over a lower strength pipe in combination with concrete support or arch designs. It is important that the pipe bedding should be properly constructed to allow for the flexibility at the pipe joints and to ensure uniform pipe supports. Point supports or loads which may lead to pipe failure must be avoided.

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The soil load to which a rigid pipe can be subjected to shall be determined from Martson Load Theory. According to the theory, the soil load on a rigid pipe differs from that on a flexible or semi flexible pipe. The load on a rigid pipe is a function of trench width, backfill soil type and trench depth. In a narrow trench, trench wall friction reduces the load applied by the soil backfill. Therefore, wide trench gives a more conservative loading and shall be used to determine the load on rigid pipe. Where vehicles will pass over the sewer and the sewer is laid with a cover depth of less than 2.5 m, the sewer will be subjected to additional loads from such vehicles. The Boussinesq theory should be used to determine the loads from vehicles in the design. The ultimate vehicle load to which the sewer will be subjected to shall be used for structural design. Where the sewer may be subjected to construction traffic or may have temporary shallow cover during installation, structural design must examine such loading conditions to ensure the sewer can withstand such temporary vehicle loadings. Determination of vehicle loading shall be in accordance with AS 3725 (Loads on buried concrete pipes) and AS 4060 (Loads on buried vitrified clay pipes.) Loads on buried rigid pipe for field conditions and for main roads can be found in Simplified Tables of External Loads on Buried Pipelines published by the UK Transport Research Laboratory.

b)

Flexible Pipe Structural Design:

Pipes which are classified as flexible are: i.

PE pipe

ii.

GRP pipe

iii.

ABS pipe

iv.

Steel pipe

The mode of failure of a flexible pipe is usually by excessive pipe ring deformation, except for GRP pipe which may be by excessive pipe ring strain. The occurrence of such a GRP pipe failure depends on the wall thickness. Normally a standard long term allowable ring deflection is applied for all flexible pipe. A 5% long term deflection limit has been the most commonly adopted limit and shall be used except for steel pipe with cement mortar lining. For steel pipe with cement lining, a 2% deflection limit shall be used. Where surface settlement is critical, a lower allowable deflection limit may be adopted. The resistance of a flexible pipe to ring deformation is classified by pipe ring stiffness. The stiffness classification is derived from a two point short term loading test. It is a function of the loading force divided by the specified test deflection. Flexible pipe can be made to achieve different ring stiffness by varying the wall thickness. For PE pipes, the ring stiffness can also be varied by varying the wall structure.


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Similar to rigid pipe, the loading which a flexible pipe can withstand can be increased when the pipe is supported. For flexible pipes, this external ring support is more critical. Without it, a flexible pipe would fail under the loads applied by usual soil cover for gravity sewers and under vehicle loads for shallow cover force mains. By varying the pipe ring stiffness and surrounding soil stiffness, different load resistance can be achieved for flexible pipe. Flexible pipe must be completely embedded in crushed rock, with the rock to be finished at 150 mm over the top of the pipe. Crushed rock will give a uniform support around the pipe. The soil load used for structural design for flexible pipe support shall be the prism load or the weight of the column of soil directly above the pipe. Marston Load Theory mentions that this column of soil is partly supported by friction provided by adjacent soil. Therefore, this frictional support of soil column causes the load on the flexible pipe to be less than the weight of soil directly above the pipe. This frictional support may be lost with time and the design using prism load represents a conservative design. Where vehicles will pass over the sewer and the sewer is laid with a cover depth of less than 2.5 m, the pipe will be subjected to additional loads from such vehicles. The Boussinesq theory should be used to determine the loads from vehicles in the design approach in this guideline. The ultimate vehicle load to which the pipe will be subjected to shall be used for structural design. Where the pipeline may be subjected to construction traffic or have a temporary shallow cover during installations, structural design must examine such loading conditions to ensure the pipeline can withstand such temporary vehicle loadings. Granular bedding design shall be adopted wherever possible. Typical details of granular bedding for flexible pipe is given in Appendix A. The structural design of flexible pipe support must be in accordance with Australian Standard AS/NZS 2566, which uses a modified form of Spangler’s equation for the determination of pipe deflection. This Spangler equation incorporates Leonhardt’s factor to account for the change in support provided by surrounding soil stiffness when the trench width is varied. For force mains with shallow cover, structural design of flexible pipe may not be necessary. However, when the structural design of flexible pipe for such a force main is undertaken, the re-rounding effect of internal pressure should be ignored to allow for the worst case design, which occurs when the line is out of service.

2. 2

Manhole

2.2.1

General Pre-cast concrete manholes shall conform to MS881 and BS5911. Manholes shall be constructed with pre-cast concrete sections surrounded by an in-situ concrete surround. Protecting lining/coating shall be provided to prevent corrosion of the

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concrete due to sulphide attack. Walls shall be either rendered with sulphate resistant cement mortar at least 20mm thick or lined with PVC, HDPE or epoxy coating. PVC or HDPE lining shall be at least 5mm thick. Continuity of the lining shall be provided by means of welding or fusing each individual sheet to the next prior to the concrete curing. The epoxy coating shall either be high build tar epoxy system complying with AS 3750.2 and applied in two or more coats to give a total dry film thickness of not less than 500µm; or high build micaceous iron oxide pigmented epoxy system complying with As 3750.12 and applied in two or more coats to give a total dry film thickness of not less than 250 µm. The benching shall be protected with epoxy coating, high alumina cement mortar, or equivalence. Only materials and application processes approved by the Commission may be used. Brick manholes shall not be used, due to the high risk of excessive infiltration. Details of manhole types and construction are shown in Appendix A. Straight back type taper top shall be used while reducing slabs type are acceptable as alternative. Any other type of pre-fabricated manhole will require prior approval of the Commission. The minimum diameter of manhole chambers constructed from pre-cast concrete rings shall be as given in Table 2.6 below:

Table 2.6 Minimum Manhole Diameters Depth to Soffit from Cover Level (m)

DN Largest Pipe in Manhole (mm)

Min. Internal Dimensionsa (mm)

< 150 225 to 300 375 to 450 525 to 710 820 to 900 > 900

1000 1200 1350 1500 1800 Subject to designer’s requirements based on site condition 1200 1350 1500 1800 Subject to designer’s requirements based on site condition

< 1.5

< 300 375 to 450 525 to 710 820 to 900 > 900

> 1.5

Note: a These sizes apply to straight-through pipes; larger sizes may be required for

turning chambers or chambers with several side branches or where specific maintenance requirements are necessary, e.g disconnecting traps.

An induct vent shall be provided at manholes receiving pumping discharges where retention times in the force mains exceed two hours and where concrete pipe are laid downstream of the force mains. The induct vent shall have a diameter of approximately one half of the force mains but shall not exceed 300 mm in


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diameter. The top of the concrete support of the vent shall be built up above flood level. Details of the induct vent are shown in Appendix A. Provision of back-drop manhole shall be based on the following criteria:a) b)

2.2.2

for pipe size equal to 225 mm or less, back-drop manhole shall be provided when the difference in invert level is equal to 900 mm or more. for pipe size more than 225 mm, back-drop manhole shall be provided when the difference in invert level is equal to 1000 mm or more.

Manhole Location Unless otherwise agreed by the Commission, all manholes shall be sited in public road reserve so that access can be gained for maintenance purposes. Manhole shall be provided for the following locations: i.the starting end of all gravity sewers, this may be replaced by a terminal layout ii.every change in direction or alignment for sewers less than 600 mm in diameter iii.every change in gradient iv.every junction of two or more sewers v.every change in size of sewer Unless adequate modern cleaning equipment is used for the maintenance of the sewer, the spacing between manholes shall not be more than 100 m for sewers less than 1.0 m in diameter. For sewers with diameter larger than 1.0 meter, the spacing between manholes shall not be more than 150 m. Where site conditions prevent manhole construction on the existing public sewer, a manhole shall be provided on the connection pipe as near to the public sewer as possible. The connections, details, and methods of manhole construction not covered in this guidelines shall be in accordance with MS 1228. In addition, the current policies of the Commission with respect to safety and operation shall be strictly followed.

2.2.3

Pipe L engths f rom M anhole To prevent the differential settling of the manhole and the connecting sewer from breaking the sewer pipe, rotational flexibility in the sewer close to the manhole is required. A single flexible joint placed immediately outside the entry to the manhole is not sufficient to solve the differential settlement problem, unless graded (governed by gradient permissible range) to connect directly to match invert level of manhole channel, if unable to match invert level. A short length of “rocker pipe” having a flexible joint at both ends shall be provided. A 600 mm length short “rocker pipe” is sufficient to provide the rotational flexibility required for most circumstances in small diameter pipelines (≤300 mm). For larger pipe, a 900mm length short “rocker pipe” shall be provided. Refer to drawings in Appendix A.

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2.2.4

Structural Design Considerations for Manhole i.

Concrete used in situ shall be 25Mpa Portland cement unless shown otherwise by the Qualified Person.

ii.

A cement blinding with a minimum of 50 mm thickness shall be placed before pouring the concrete manhole base.

iii.

The base of the manhole shall not be less than 300 mm thickness, which is measured from the channel invert.

iv.

Channel inverts shall be laid accurately to meet entry and exit pipe inverts.

v.

The channel invert shall be graded evenly between the entry and exit pipes

vi.

Flexible joints shall be provided at the exit and entry of the manholes and shall be placed immediately outside any poured-in-situ concrete surround.

vii.

Joints between the pre-cast chamber rings shall be sealed with suitable mortar, which can be high alumina cement mortar or equivalence.

viii.

The top of the benching shall be sloped at 1 in 12 towards the channel.

ix.

The finish surfaces of cast in-situ concrete structures shall be trowelled smooth without poke holes or exposed aggregate.

x.

A minimum of 150mm thick Grade 25 concrete in-situ shall be encased to the precast concrete section. Brick manholes shall not be used.

xi.

Box outs sealed with bricks or equivalence shall be made for any proposed connections.

xii.

Drop connection pipes and fittings in the manhole shall be of the same

xiii.

diameter and material as the connecting sewer. A factory pre-cast intermediate slab shall be provided at every 3 meters depth and placed at half of the manhole depths. The slabs must have holes for ventilation.

xiv.

Pre-cast reinforced concrete landing, cover slap and flat top’s undersides shall be painted with 2 layers of coal tar epoxy.

xv.

Manhole covers in roads shall be set to the road profile and shall be flushed with the road surface.

xvi.

Manhole covers in unimproved areas shall be set at an elevation to prevent entry of surface water.

xvii.

Manhole frame surrounds shall be filled with 1:3 cement mortar.

xviii.

Field coatings to manhole covers and frames shall be applied to surfaces that are clean, dry and free from rust.

xix.

Bolted-in steps are not permissible in all manholes. Provision shall be provided for portable ladder for access. The lightweight removable ladders shall be used in manholes where they can easily be inserted and secured from the surface, in order to deter unauthorized access to sewers.

xx.

Maximum depth shall be equal or less than 9 meter and all manholes deeper than 6 meter are subjected to the Commission’s prior approval. Depending on the catchment are and size of sewer pipe, manholes deeper than 9 meter may be considered for the Commission approval.


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xxi.

Precast or cast in-situ concrete base of minimum grade 20 with 1 layer of A6 BRC, 300 mm thick or to Qualified Person’s design shall be provided under poor soil condition including piling, if necessary.

2. 3

Manhole Covers and Frames

2.3.1

General Manhole covers and frames shall comply with the specifications in this guideline and BSEN124. Where the specifications in this inguideline contradict the specifications given in BSEN124, the specifications this guideline shall take precedence.

2.3.2

Load Class Manhole covers and frames shall be capable of bearing wheel loads of up to 400 kN and, as such, shall meet the test load requirements for Class D400 manhole covers and frames given in BSEN124.

2.3.3

Material The material for manhole covers and frames shall be of spheroidal or nodular graphite iron (otherwise known as ductile iron) complying with the requirements specified in BSEN1563 for Grade 500/7. The production, quality and testing of spheroidal graphite cast iron shall comply with ISO 1083.

2.3.4

Dimensions, M arking and Surface Finish The manhole covers shall be free of defects which might impair their fitness for use. The dimensions, marking and surface finish of manhole covers and frames shall comply with the requirements given in Figure A.1 to A.4 in Appendix A. Tolerance on dimensions shown in Figures A1 to A2 shall be of markings shall be clearly legible.

2.3.5

± 1 mm. The casting

Seating When a random cover is placed in a random frame, the adjacent top surfaces of the cover and frame shall have flushness of level within ± 1 mm. The manholes covers shall be compatible with their seatings. These seatings shall be manufactured in such a way to ensure stability and quietness in use.

44

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2.3.6

Casting All cast units shall be cleanly cast and free from air holes, sand holes, cold shuts and chill. They shall be neatly dressed and carefully fettled. All castings shall be free from voids, whether due to shrinkage, gas inclusions or other causes.

2.3.7

Protective C oating All surfaces of manhole covers and frames shall be supplied coated with either a:

i.

hot applied bituminous material complying with BS 4147 Type I Grade C

ii.

cold applied bituminous material complying with BS 3416 Type II

Immediately prior to coating, surfaces shall be clean, dry and free of rust. The coating shall be free of bare patches or lack of adhesion. The mean thickness shall be no less than 70 µm and the local thickness shall be no less than 50 µm.

2.3.8

Water-tightness No visible leakage shall occur between the manhole cover and its seating in the frame when tested in accordance with Appendix E of AS 3996.

2.3.9

Safety Features Manhole covers shall be provided with locking device and hinge to prevent rocking due to traffic and to provide a theft proof design.

a)

Locking Devices

Locking devices shall be either bolts and nuts or a mechanism with a special key design. The mechanism shall be able to be integrated with the covers and can also be used as a lifting device. All the mechanism for locking device shall be of stainless steel in accordance with BS EN ISO 3506. Bolts and nuts for locking devices shall be hexagonally headed, complying with BS3692.

b)

Hinge

All manhole covers shall be hinged. The hinge shall be designed such that, when in the open position, they shall be secured by a positive mechanical retainer to prevent accidental closure of the covers. The opening angle of hinged covers shall be at least 100o to the horizontal. If hinge bolt is used for coupling separate sections of covers and frames, it shall be of stainless steel in accordance with BS EN ISO 3506.

2.3.10

Product Certification Manhole covers and frames shall be certified as complying with the requirements of this specification. The product testing for certification purposes shall be undertaken by SIRIM QAS, IKRAM QA services or other third party certification body. The approval of the product shall be from the Commission.


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The quality control of the certified manhole covers and frames shall meet the requirements given in Clause 10 of BSEN 124. However, the final inspection and tests and the frequency of tests/inspection shall not be as shown in Table A3 of BSEN 124. Instead, the specifications as shown in Table 2.7 below must be followed. All final inspection and test documents shall be retained for at least 5 years.

Table 2.7

Final inspection and testing

FinaT l est/Inspection Markings legibility inspection

Frequency Every unit

Casting defects inspection

Every unit

Protective coating inspection

Every unit

Locking devise inspection

Every unit

Seating flushness of cover in frame

1 per 20

Measurements of all dimensions

1 per 100

Load Class Test

1 per 100

Water-tightness Test (only applicable for covers required to be watertight)

1 per 100

Protective coating thickness measurement

1 per 200

2. 4

Design of Network Pump Stations

2.4.1

Specifying of Network Pump Stations Network pump stations shall be provided only where: i.

2.4.2

46

Sewage flow by gravity is not allowed by the topography

ii.

Excessively deep and expensive excavation for sewer installations will be required

iii.

Sewage needs to be delivered from an area that is outside the natural drainage catchment of a sewage treatment plant

General R equirements i.

Network pump stations shall be preceded by screens to protect pumps from being damaged or clogged.

ii.

The type of pump used must be suitable for sewage application. Water pumps must not be used as they are not designed to transfer sewage.

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iii.

Drainage of dry wells and valve pits shall be provided. Drainage lines shall be equipped with back flow protection to ensure that the chamber is not flooded.

iv.

Wherever possible, the wet well shall not be housed within a building structure with insufficient ventilation.

v.

Where separate valve pits are used, then the connecting pipes shall incorporate at least two flexible joints to allow for differential settlement.

vi.

The designer shall ensure that his/her designs comply with all relevant legislation, standards, guidelines and requirements, and its latest

vii. viii.

2.4.3

amendments. Access and appropriate parking shall be provided at all times for emergency vehicles, maintenance vehicles and ancillary equipment. Adequate protection against lightning shall be provided

Buffer Requirements In order to minimise the nuisance of odours from pumping stations, buffer zone shall be provided at all sides. The zone shall be at least 20 m from the pumping station fence to the nearest habitable building fence. The presence of a pumping station in any development may draw negative visual impacts. To minimise the visual impact of surface structures of the pumping station, landscaping shall be provided. Landscaping shall comprise of trees that are non-shedding to minimise maintenance. The buffer requirements are shown in Appendix A. Under conditions where there exists the potential of odour nuisance to the nearest habitable building property line within residential and commercial development despite having the minimum buffer zone, such odour shall be minimised to the lowest possible level and in compliance with the EQA.

2.4.4

Pipework Requirements i.

Pipe work shall be of ductile iron with approved internal lining. Other approved material by the Commission may be used.

ii.

External surface of pipe work in chambers and wells shall be epoxy coated.

iii.

Buried ductile iron pipe shall have polyethylene sleeving.

iv.

Pipe work shall be adequately supported

v.

Flanges shall be located at least 150 mm away from structures.

vi.

Dismantling joints such as bends shall be provided.

vii.

Pumping thrust shall be resisted using pipe supports

viii.

All internal pipework within the pump station shall have flanged joints unless the pipe selected has special jointing requirements.

ix.

Flexible couplings should be used where they will facilitate dismantling and accommodate vibration.


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2.4.5

Wet-well Requirements i. ii.

Automatic flushing of grit and solids is required for plants of PE > 2,000.

iv.

The difference between stop and start levels shall be a maximum of 900 mm and a minimum of 450 mm.

v.

The difference in level between start or stop of duty and assist pumps shall be greater than or equal to 150 mm.

vi.

The minimum sump volume required shall accommodate the pumping cycle as per Table 2.4.

vii.

Benching shall be designed to minimise deposition of solid matter on the floor or walls of wet wells. The minimum slope of benching shall be 45o to the horizontal.

ix.

Benching shall preferably extend up to the pump intake. Self cleansing pumps shall be provided.

x.

Access into wet wells can be by vertical rung ladders with a maximum height of 6 m. When the height exceeds 6 m, intermediate platforms shall be provided with a change in direction of the ladder. Safety cages shall be provided for ladders exceeding 6 m.

xi.

Access covers shall have a minimum clear opening of 600 mm diameter and be sufficiently large to withdraw pumps vertically.

xii.

Access covers shall be capable of being lifted by, at most, two operators.

xiii.

On small pump stations (PE < 500), the practice is to provide difference between the cut-in and cut-out levels, the storage volume equal to 2 to 3 times the peak flow into the wet-well in litres per minute merely to protect the starting equipment from overheating and failure caused by too frequent starting and stopping.

xiv.

Emergency by-pass shall be provided either at any suitable manhole or wetwell. The discharge of the by-pass is preferred to the nearest watercourse and not to the perimeter drain of the pumping station. However, if this is not available then discharge to the nearest surface drain is allowed.

xv.

All wet-well shall be opened and come with stainless steel or other noncorrosive handrails. If stainless steel tubing is used, it shall be in-filled with concrete.

Dry-well Requirements i. ii.

48

Minimum hopper bottom slope shall be 1.5 vertical to 1.0 horizontal.

iii.

viii.

2.4.6

Suction channels shall be designed to avoid "dead zones", i.e., prevent solids and scum accumulation.

The size of dry well depends primarily on the number and type of pumps selected and on the piping arrangement. The requirement of pump installation is to provide at least 1.0m from each of the outboard pumps to the nearest side wall and at least 1.2m between each pump discharge casing.

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iii.

iv.

v.

2.4.7

Sufficient room is required between pumps to move the pump off its base with sufficient clearance left in between the suction and discharge piping for site repairs, inspection or removal from the pit to the surface for repairs. Consideration should be given to the installation of monorails, lifting eyes in the ceiling and A-frames for the attachment of portable hoist cranes and other devices. Provision should also be made for drainage of the dry well to the wet well.

Structural Re quirements i.

Substructure shall be constructed of reinforced concrete with sulphate resistant cement to resist aggressive soils and groundwater.

ii.

Below ground walls shall be waterproofed and protected against aggressive soils and ground water.

iii.

Safe and suitable access to the wells shall be provided.

iv.

Internal walls shall be made resistant to sulphide corrosion by coating with high alumina cement or equivalent coatings.

v.

A penstock shall be installed upstream of the wet well to isolate the pump station.

vi.

For safety and operational reasons, a double penstock system may be required at specific plant.

vii.

The penstock spindle shall extend to pump station ground level and shall be suitably positioned to allow unrestricted operation of the penstock.

viii.

Access platforms shall be provided at all locations where dismantling work

ix.

takes place. Access covers shall be hinged with a lifting weight not exceeding 16 kg.

x.

Internal walls shall be made resistant to sulphide corrosion by coating with high alumina cement mortar lining, PVC lining or epoxy coating. Other materials used under special circumstances are subjected to approval from the relevant authority.

xi.

Penstock greater than 610mm x 610mm shall be motorised and come with manual overwrite switches. The actuator shall be located above ground level and above flood level for easy access in the event of flooding.

xii.

Protection against falling shall be provided by means of handrails at walkways and other working areas, where the fall equal or exceeds 1.5 m.

xiii.

Edge protection by means of kick plates of at least 50 mm in height shall be provided, where the drop is equal or exceeds 2.0 m.

xiv.

Proper drainage shall be provided at the collection bin area to ensure that liquid collected could be channelled back to the pump sump.

2.4.8

Ventilation Requirements i. ii. iii.

Ventilation shall be provided for all hazardous zones of the pump station. Covered pits shall have mechanical ventilation. Separate ventilation shall be provided for wet wells and dry wells.


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iv. v. vi.

2.4.9

2.4.10

Permanent ventilation rate and air changes shall comply with MS 1228. uPVC pipe is not permitted to be used as ventilation ducting between wetwell and dry-well.

Odour Control i.

the potential for odour generation, its impact and treatment, shall be considered in all aspects of design

ii.

isolate odorous gasses from general ventilation exhausts by containing identified odour generating sources with a separate local exhaust system

iii.

containment of the odour sources shall be by installing lightweight and corrosion resistant covers/enclosures designed for practical operation and maintenance works

iv.

the local exhaust odorous air shall be conveyed through well designed and balanced ductworks by a centrifugal fan to an effective odour treatment equipment

Requirements for Lighting and Electrical Fittings i.

Wet wells and dry wells shall be adequately lit.

ii.

Electrical installations shall be water proof, vapour proof and explosion proof.

iii.

If lights are fitted outside the well, then a spotlight system may be used to provide adequate illumination.

iv.

If portable lighting is used, proper ancillaries shall be made available.

v.

2.4.11

Lighting systems shall be interconnected with ventilation.

Equipments shall be sited above the highest water level.

Acceptable Pump System (Fixed Speed Pumps Only) The acceptable pump types are: i. ii. iii.

Centrifugal Screw Screw Centrifugal

Pumps are to be equipped with an auto restart mechanism to allow for automatic pump restart after power supply has resumed fromsensor, a power failure.sensor, Pumpsetc. shallDry be equipped with protection accessory, e.g. thermal leakage well mounted pumps shall be equipped with auxiliary services such as cooling and gland seal water supply. Guide rail, lifting device and other wet well fittings must be fabricated of stainless steel, that is corrosion resistant. The use of hot dip galvanised iron is not recommended.

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Pre-fabricated pump stations are acceptable for small installations of PE less than or equal to 2,000.

2.4.12

Valve R equirements

2.4.12.1

General i.

All valves shall be anti-clockwise opening.

ii.

All valves shall be suitable for use with wastewater and shall be designed to

iii.

prevent retention of solids. All valves shall be identified by durable name plate. Direction of flow shall be stamped on the valve body.

iv.

2.4.12.2

Bodies and cover for all valves shall be made of ductile iron to BS EN 1563: 1997. Special protective surfaces finishing by short blasting and finished externally with epoxy corrosion resistant coating shall be provided.

Gate V alve i.

Gate valves shall be of the non-rising screw wedge-gate type, double-faced ductile iron made and with resilient seated.

ii.

Gate valve shall conform to MS 1049, BS 5163 EN 1074 Part 2 or BS EN 1171: 2002.

iii.

The wedge of the gate valves shall be coupled and integral to the wedge hut in dezincification resistant high tensile brass (CZ 132) conforming to BS EN 2287 2: 1993, ISO 2872: 1985.

2.4.12.3

iv.

The spindle of the gate valve shall be of the inside screw non-rising with machined square or acme threads and operated by a handed or tee-key.

v.

Resilient seat valves shall have EPDM covered gates with inside screw non-rising stem. Stem shall be stainless steel conform to BS EN 10088-3: 2005.

Check Valve i.

Check valve shall be of approved by the Commission and suitable for their intended used and shall comply to BS 12334: 2001.

ii.

Check valves of non-slam swing type with extended spindle if necessary shall be provided at the upstream of a flow detection device.

iii.

Only single disc type of check valve shall be used.

iv. v.

The uses of internal counter weights are not permitted for check valve. Type non-slam check valve shall be of the full body type, with a domed access cover and only on moving pant, the flexible disc.

vi.

Disc of check valve shall be of precision molded NBR to BS EN 681-2: 2000. the disc shall be of one-piece construction, precision molded with an integral o-ring type sealing surface, and contain alloy steel and nylon reinforcement in the flexible use area.


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2.4.13

vii.

In the absence of check valve, the reverse rotation of the pump shall not exceed 150% of the rated speed or limit set by the manufacturer.

viii.

Tapping (12 mm BSP) shall be located upstream and downstream of check valves.

Requirements for Level Controls i.

Either floats, electrodes or ultrasonic level controls may be used for startstop level of pumps. Those level controls with environmental friendly features are recommended.

ii. iii.

Non-mercury type floats are recommended.

iv.

Hollow tube electrodes are not acceptable.

v. vi.

2.4.14

Level controls shall be placed where they are not affected by the turbulence of incoming flow and where they can be safely removed. When floats are used, cable hanger shall be installed.

Requirements f or A larms i.

ii.

iii.

2.4.15

Ultrasonic level control is recommended due to its clog-free nature.

Provision of alarms shall be considered inclusive of flammable gas, fire, high water level, bearing temperature, motor temperature, pump failure, power failure and vandalism. An alarm system should have an emergency power source capable operating for at least 24 hours in the event of failure of the main power supply and shall be telemetered thereto. Where no such facility exists, an audio-visual device shall be installed at the station for external observation.

Requirements of Hydraulic Design and Performance The followings items shall be provided: i. ii.

2.4.16

Pump curves

iii.

Operating point of pumps with respect to flow and total dynamic head (TDH)

iv.

Operating characteristics such as efficiency, horsepower, motor rating and NPSH

Maintenance Co nsiderations i. ii. iii.

52

System curves

Mechanical and electrical equipment selected shall be robust and reliable and shall require minimal maintenance. Consideration should also be given to the availability of spare parts. The provision of appropriate lifting hoists and beams, and lifting eyes or similar features on heavy equipment, shall be considered.

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iv.

2.4.17

Hazard and Operability i. ii. iii.

2.4.18

Complete sets of current general arrangement and sectional drawings, operational, maintenance and service manuals, circuit diagrams and parts lists shall be supplied and be available at all times.

All pumping station design shall give consideration to all potential hazard and operability of design. HAZOP study may need to be conducted for pumping station design to identify hazards andstudy operability issues. with requirements stipulated the The needthefor HAZOP shall comply Volume II.

Other Requirements Also refer to MS1228 for additional requirements.


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Table 2.8

Recommended Design Parameters for Pump Stations (continue on next page) Design Parameters

Description

Unit

Type station of Number of (all identical and sequentially)

PE

Wet well pumps work

Maximum retention time at Qave

each at Qpeak

each at Qpeak

30

30

75

75

mm

100

100

Pumping cycle (average flow conditions)

start/ hour

6 min 15 max

6 min 15 max

*-

-

5,000

2 1 duty, 1 stand-by (100 % standby)

Minimum suction and discharge openings

Liftingdevice*

54

≤

Wet well

min

mm

1,00P<0E

2 1 duty, 1 stand-by (100 % standby)

Pumps design flow

Min pass through openings

≤1,000

liftingdavit

liftingbeamandblock

Weight < 16 kg: Manual lifting 16kg ≤ Weight ≤250 kg: A davit or ‘A’ frame sha ll be arrang ed to allow item s lifted by using man ual chain hoist to be projected on a 1.2 m truck tray and positioned at 2m above road level. In the pump station, motorized hoist is required for lifting weight exceeding 100kg. Weight > 250 kg: A gantry with motorised hoist shall be arranged to allow items to be projected on a 1.2m truck tray and positioned at 2m above road level truck tray.

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Table 2.8

Recommended Design Parameters for Pump Stations Design Parameters

Description

Unit

Type of station

Number of (all identical and sequentially)

5,000 < PE

P2> E0,000

wet well and dry well

4 (2 sets) 1 duty, 1 assist, per set (100 % standby)

6 (3 sets) 1 duty, 1 assist, per set (50 % standby)

each at 0.5 Qpeak

each at 0.25 Qpeak

30

30

Pumps design flow

Min pass through openings

0,000

wet well or dry well up to 10,000 PE 10,000 PE above – wet well and dry well pumps work

Maximum retention time at Qave

2≤

min

mm

75

75

Minimum suction and discharge openings

mm

100

100

Pumping (average flow conditions)

start/ hour

6 min 15 max

6 - 15

cycle

Lifting device* *-

-

Mechanicaland block

mechanical

Weight < 16 kg: Manual lifting 16kg ≤ Weight ≤250 kg: A davit or ‘A’ frame shall be arran ged to allow item s lifted by using manu al chain hoist to be projected on a 1.2 m truck tray and positioned at 2m above road level. In the pump station, motorized hoist is required for lifting weight exceeding 100kg. Weight > 250 kg: A gantry with motorised hoist shall be arranged to allow items to be projected on a 1.2m truck tray and positioned at 2m above road level truck tray.


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2. 5

Interceptors All development schemes including individual premises that involve any sewerage works are vetted by the Director General. As part of this vetting, a check is made on the means of protecting public sewers from the discharge of prohibited matters such as oil, grease, petrochemicals, fats and solid food wastes. These matters can lead to congealment, constriction and blockage of sewers and pipelines and can also present hazards for sewer operations and maintenance. Therefore, suitable interceptors must be provided on the sewerage systems of garage workshops, engineering workshops, canteens or any premises that collect such matters. The design specfication may be acquired from the Director General for such a system.

2.5.1

Oil Interceptors Oil interceptors shall be provided in drain lines from areas such as garages, parking zones, service stations, machine shops and industrial plants where oil sediments and other volatile liquids are generated. Oil interceptors shall be designed in such a way that pollutants that are lighter than water liquid are trapped in a chamber and are prevented from being discharged to the public sewer. The chamber shall be normally fitted with a device to trap sediments and heavy particles that settle to the bottom. The removal of these sediments is required periodically. Intercepted oils shall be capable of being drained off for storage from suitable draw off points on a continuous operational basis. The interceptor shall be sized to accommodate the pollutants. volumes of liquid likely to be discharged into the drainage system and the trapped

2.5.2

Grease Traps Grease traps shall be provided in drain lines from areas such as restaurants, canteens, food processing and animal product or feeds factories, where grease and fat are likely to present in wash down waters or sullage. Grease traps shall be designed in such a way that solidified grease and fats are trapped in a chamber prior to discharge and may be skimmed off by means of a perforated strainer or bucket. The trap shall be sized adequately to contain the volume of liquid to be discharged from the drain line and the accumulated grease.

2. 6

Concrete and Reinforcement Requirements Unless otherwise specified in other sections of this guidelines, all the concrete and reinforcement designed for pump stations and sewer networks shall comply with the following subsections.

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2.6.1

Concrete i.

Structural use of concrete shall be designed in accordance with MS 1195

ii.

Concrete shall generally comply with the relevant requirements in MS 523

iii.

Concrete for purposes other than manholes and pumping stations shall have a strength grade not less than Grade C20 where unreinforced, and not less than Grade C30 where reinforced

iv.

Structures that are designed for retaining sewage or other aqueous liquids shall be in accordance with BS8007, which specifies C35A concrete. Where required, higher strength grades may be specified by the Director General.

v.

Concrete exposed to a sewage atmosphere shall be lined with minimum 20 mm high alumina cement mortar complying with BS 915 Part 2 or 2 mm epoxy coating using a method of application approved by the Commission.

vi.

Concrete and cement mortar shall be made using a cement with sufficient resistance to sulphate attack if contacted with sewage

vii.

Approval for admixtures shall be obtained prior to inclusion in the concrete mix. All admixtures shall comply with MS 922

Aggregates shall comply with MS 29 and shall be coarse aggregate of maximum 20 mm nominal size

2.6.2

Cement One of the following cement shall be used to resist sulphate attack:

2.6.3

♦

Sulphate-resisting Portland cement complying with MS 1037

♦

Portland pulverised fuel ash cement complying with MS 1227

♦

Portland blastfurnace cement complying with MS 1389

♦

High silica content Portland cement complying with AS/NZS 3582

♦

Super-sulphated cement complying with BS 4248

Steel Reinforcement and Falsework

♦

♦

Steel reinforcement shall comply with: 1.

MS 144 for cold reduced mild steel wire

2.

MS 145 for steel fabric

3. MS 146 for hot rolled steel bars Scheduling, dimensioning, bending and cutting of steel reinforcement shall be in accordance with BS 8666

♦

Welding of steel reinforcement shall be in accordance with BS 7123

♦

Falsework shall be in accordance with BS 5975


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57


58 (this page is intended to be blank)

Volume3

MalaysianSewerage Industry Guidelines

Secti on 3 Construction and Installation

Construction and Installation

3.1

Introduction The correct installation of sewer systems is critical to the efficient and effective sewer system operation. Poor construction practice causes defects in the sewer at joints, along pipe barrels, at manholes, transition points (e.g. pipe to manhole), etc. Adequate site supervision and certification by consultants, with reference to approved design drawings, are therefore also required. The various construction and installation aspects of sewer system can be divided into: i.

Pipes and Fittings Delivery and Handling

ii.

Trench Excavation

iii.

Pipe Laying

iv.

Pipe Jointing

v.

Special Requirements for Ancillaries and Protection

vi.

Connections to Public Sewers

A description of the requirements for each stage is given below.

3.2

Pipes and Fit ti ng s Deliv ery and Handl ing

3.2.1

Pipes and Fitt ings Delivery a)

Materials delivered shall be from approved suppliers.

b)

Pipes and fittings on the delivery truck shall be secured firmly without damaging the pipe and fittings. Pipes and fittings shall be protected from any damage from the chain securings by using rubber, carpet or textile paddings.

c)

Pipes and fittings shall be checked to ensure that they have not moved during transportation.

d)

The pipes and fittings shall not be stacked in contact with each other and shall be separated by wooden spacers. The pipes stack can be secured by strapping or crating or can be secured by chocks at the outer pipes of each layer.

e)

Sockets of pipe in adjacent layers should be placed at opposite ends. Alternatively, sockets of adjacent pipe can be placed at opposite ends.

f)

Thermoplastic pipes (PE, ABS) shall not be supported in such a way that will cause the pipes to be twisted or bowed.

g)

Sewer pipe and components shall be checked for damage before being removed from the delivery truck


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59


3.2.2

60

h)

The delivered pipes and fittings shall be checked against the design drawings and the delivery docket to ensure the pipe and fittings delivered are of the strength, stiffness, pressure class, length, joint type, diameter, fitting type, etc. specified.

i)

The delivery truck shall be positioned on a flat ground or in such a way that pipes and fittings would not fall off the truck when unsecuring the fastenings.

j)

Pipes and fittings shall not be pushed off the delivery truck and shall not

k)

be allowed to drop to the ground. When pipes are delivered in crates, the crates shall be removed intact, wherever possible.

l)

Pipes and fittings shall be lifted from the delivery truck using approved slings. Plastic covered wire mesh slings, hemp rope slings and chain slings without rubber sleeving are not suitable. For plastic pipes or pipes with external coating, webbed synthetic slings shall be used.

m)

Alternatively, pipes and fittings can be removed from the delivery truck by rolling a pipe at a time down the wooden runners. The pipe rolling shall be simultaneously controlled by ropes.

n)

Uncrated light thermoplastic pipes shall be lifted manually and carefully off the truck and shall not be dragged across the truck bed, edges or other hard and sharp surfaces. This is to avoid the scoring of plastic pipe.

Pipe Handling at Site a)

Pipes shall not be dragged or pushed over the ground.

b)

Pipes and fittings shall not be dropped in any way.

c)

Pipes and fittings shall not knock against each other or any other objects.

d)

The pipe lifting shall be controlled, where necessary, using ropes or by hand to ensure they do not knock against other objects.

e)

When rolled, pipes shall be rolled on smooth timber bearers, which are free of nails, fasteners, etc., and sufficiently raised above the ground to prevent hitting any rocky ground, tree roots, etc.

f)

When rolled on timbers, pipes shall not be pushed with a machinery bucket.

g)

Pipes with external coatings shall not be rolled. Instead, these pipe shall be lifted into place.

h) i)

Pipes and fittings shall be lifted using approved slings Pipe lifting equipment shall be of sufficient strength and reach to lift the intended individual pipe or crate of pipes.

j)

Mechanical lifting units (cranes, backhoes etc.) shall be stable or properly stabilised prior to lifting operations to ensure they would not tip and damage pipe and fittings.

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3.2.3

k)

The slings or chains used for lifting the load shall be secured to the load in the right manner to ensure the load does not slip or tilt excessively.

l)

All other safe lifting procedures not covered above shall be adopted.

m)

The lifting and moving of all the steel pipes and any pipes that contain internal linings shall follow the manufacturer instructions.

Pipe Storage a)

The pipe and fittings storage area shall be away from traffic and shall not obstruct any property access or pedestrian route.

b)

The pipe and fittings storage area shall be at a location that allows lifting machinery to position easily and safely for lifting pipes and fittings.

c)

Pipes shall be stacked on a flat and level firm ground or the base of the pipe stack shall be made level using additional solid timbers under base bearers.

d)

There shall be no rocks, tree roots, etc. under the pipe stack, which may cause point load.

e)

The sockets shall be alternated to different ends for each pipe stack layer. The sockets shall be protruded out of the stack.

f)

The base timber bearers shall be sound and without protrusions. The cross section of each timber shall be at least 75 mm by 75 mm. The base bearers shall provide support near the pipe ends, but placed behind sockets. The placement of base bears shall not be more than 1.5 m apart.

g)

VC, RC, DI, Steel and GRP pipe layers shall be separated using timber spacers of at least 50 mm wide and 50 mm thick. These spacers shall not be placed more than 1.5 m apart. These spacers will prevent pipes in each layer from touching pipes in the next layer.

h)

For VC and RC pipes that are not crated, the pipes shall not be stacked more than 3 pipes high. The pipe stacks shall be wedged to prevent them from rolling off the stack.

i)

Thermoplastic pipes (PE and ABS) shall be stacked in such a way to prevent them from being twisted or bowed.

j)

Thermoplastic pipes shall be either stacked in a pyramid with no more than 1 m high or in a square with vertical side supports for more than 2 pipes high.

k)

Plastic pipe and fittings shall be kept under a cover that prevents direct exposure to sun light.

l)

Plastic pipe and fittings shall not be covered with plastic sheeting.

m)

Plastic pipe and fittings shall be stored away from oils, greases, solvents and other aggressive chemicals.

n)

Plastic pipe shall be stored away from sources of heat such as engine exhausts.

o)

Care shall be taken to prevent scoring and scratching of plastic pipe and fittings.


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3.2.4

62

p)

Joint lubricants, rubber rings and other jointing materials shall be stored in a secured area that cannot be accessed by the public.

q)

Any safe pipe stacking procedure not covered above, but recommended by the manufacturer, shall be adopted.

r)

The rubber rings that are not delivered fitted to the pipe socket or sleeve shall be stored away from direct sunlight or continual artificial light. Also, the rubber rings shall be stored in a cool area that is away from oils, greases or other petroleum products.

s)

When rubber rings are delivered fitted to a pipe socket or sleeve, the pipe ends with the rubber ring shall be shielded from sunlight using a hessian cloth.

t)

Rubber rings shall be retained in the srcinal sealed packaging until they are required.

Pipe Damage a)

Pipes, fittings (including coatings and linings) and rubber rings shall be inspected for damage on delivery, immediately before laying and after laying.

b)

Damaged pipe and fittings shall be identified and marked with an indelible marking of “Damaged” in a clearly distinguishable colour.

c)

Damaged rubber rings shall be cut through completely to prevent inadvertent use.

d)

Damaged pipe, fittings, and rubber rings shall be set aside and separated from the undamaged components.

e)

Pipes or fittings shall only be repaired if they can be restored back to a satisfactory state. Approval for repair shall be sought from the Commission before the repair.

f)

Pipes or fittings that are damaged and are in a repairable state shall be repaired according to the manufacturers instructions.

g)

Damaged pipe and fittings that are not permitted to be repaired shall be removed from the site as soon as possible.

h)

PE and ABS pipes with damage in the barrel, shall have the damaged section and at least 100 mm either side of the damage cut from the barrel.

i)

Repaired pipes and fittings shall be used only after the approval for reuse from the Commission is granted.

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3.3

Trench Excavation

3.3.1

Prot ectio n of Aff ecte d Servic es, Stru ctu res, Pavements and Vegetation a)

Owners of affected property, structures, services and other pipelines (sewer, water, gas, electricity, telecommunications lines, fuel lines, chemical pipelines) along or within 3 m of the excavation shall be notified.

b)

Services and other pipelines shall be protected, uncovered, temporarily supported or temporarily relocated in accordance with the conditions specified by the owner.

c)

Where the shutdown of a service or pipeline cannot be avoided, arrangements shall be made with the owner of the service or the pipeline on the closure and reinstatement requirements.

d)

Damages to any affected structure, service or pipeline shall be avoided.

e)

Damage to any structure, service or pipeline shall be informed to the owner and shall be repaired as quickly as possible in accordance with the requirements of the owner.

f)

Damage to vegetation (trees, bushes, gardens), paved areas (roads, footways, kerbs), fences or other property within the construction zone shall be minimised.

g)

The length of time that any paved route is out of use shall be minimised.

h)

Not more than half the width of a roadway shall be disrupted at any one time.

i)

Spoils shall not be placed on road surfaces. Where there is no other approved storage area, spoil shall be carted away.

j)

Non-reusable material excavated from roadways shall be disposed of in an appropriate manner. Only fillings approved by the responsible authority for the roads shall be used as refill.

k)

Excavations shall be sufficiently clear of building foundations.

l)

Excavations adjacent to roads shall be at least 1 m clear of the road edge except when otherwise approved by the Director General.

m)

Trenches adjacent to roads, buildings and structures shall be continuously supported until the trench is refilled.

n)

Structures, services, vegetation, paving, or other property not within the construction zone shall not be damaged.

o)

Temporary fencing shall be provided where barriers such as fences and walls are dismantled.

p)

Warning signs and temporary fencing shall be provided at the work site for excavation spoils, access routes, steep or loose slopes resulted by excavation work.


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q)

3.3.2

Warning signs shall be in accordance with the relevant Malaysian Standards. Some of the relevant Malaysian Standards are:

i.

MS 980 Specification for safety signs and colours: colorimetric and photometric properties of materials

ii.

MS 981 Specification for safety signs and colour: colour and design

iii.

MS 982 Specification for safety signs, notices and graphic symbols

r)

Adequate lighting and reflective signals, which can make clearly visible the perimeter of the work site to pedestrians and traffic, shall be provided.

s)

Adequate lighting shall be provided for works undertaken in poor lighting or at night. Lighting in confined spaces shall be explosion proof.

t)

Alternative means of access shall be provided to rights of way, buildings and property where usual means of access are disrupted by the excavation.

u)

Soils shall not be taken out of the work site, put onto pavements or flushed down to drains or water courses.

v)

Road drains, gutters and channels shall not be obstructed.

w)

Drains disturbed by works shall be rerouted to ensure continual operation.

x)

Sufficient top soil that will be used for surface reinstatement shall be removed and stockpiled separately.

y)

When dewatering, care shall be taken to ensure that the adjacent structures,

z)

services and building foundations are not affected. Water removed from the excavation shall be disposed of without damaging other property or causing a public nuisance.

Excavati on Requirements a)

The required line of the sewer and manhole locations shall be set out using accepted surveying practices.

b)

Manhole locations shall be pegged and the line of the excavation between manholes shall be maintained straight using one or more of pegs, chalk lines laser beam lines and string line.

c)

Changes to the line, grade or level due to unforeseen obstructions or proximity to services shall be approved by the Commission prior to making the actual changes.

d)

The trench shall be excavated precisely along the marked alignment to ensure the sewer will be in the centre of the trench.

e)

The trench shall be excavated to a depth so that the sewer can achieve the specified level and grade when the specified bedding depth is used.

f)

Over-excavation of the trench depth shall be avoided.


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g)

For open excavation, depending on depth of sewer and soil condition, sufficient slope protection must be provided and supported by approved consultant drawings and design.

h)

When the excavations are required to cross rivers, railway lines, and any other obstructions, minimum soil cover requirements specified by the responsible authorities shall be observed. In extreme cases, inverted siphons may be necessary. Minimum requirements for inverted siphons are shown in the standard drawings in the Appendix, and they must be designed individually based on actual locations.

i)

When working with poor ground conditions, construction depth shall be minimised. Reference shall be made to the approved longitudinal and crosssectional sewer profile drawings, which give details of construction based on soil reports.

j)

The base of the trench shall be trimmed carefully to level and grade.

k)

Where sight rails are used to determine trench excavation depth, at least three sight rails shall be used for each manhole length.

l)

Sight rails shall be fixed to a uniform height above sewer invert.

m)

Rocks that cause an uneven trench base shall be removed. The resulting holes shall be refilled with the specified embedment material.

n)

The trench in the pipe zone shall be excavated to the minimum width limits as given in the specification, except where a wider trench is needed due to unsupportive soil adjacent to the pipe zone.

o)

The trench sides shall be vertical except where permitted otherwise by the Commission.

p)

To prevent trench wall from collapsing which may lead to injuries and pipe damage, timber or steel support shall be provided in the trench when the trench is deeper than 1.5 m. These supports must be adequately designed for.

q)

Where possible, spoil shall be placed only on one side of the trench.

r)

Spoil shall be placed at an appropriate distance away from the edge of the trench (minimum 600 mm). This is to prevent the spoil material from falling into the trench or to prevent the weight of the spoil from collapsing the trench wall.

s)

Unsupportive (very soft, loose, spongy or puddly) soil in the base of the trench (as determined by the Commission) shall be removed and replaced. The replacement based shall be sufficiently supportive and shall require approval from the Commission.

t)

Excessive excavation shall be refilled with approved materials to the specified compaction.

u)

Where possible, the excavated trench shall be kept free of water until sufficient backfill is placed above the sewer. This is to prevent the base of the trench from becoming spongy and to prevent the pipe from moving off line or grade.


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3.3.3

v)

Changes to the line, grade or level of the sewer shall be properly recorded for incorporation in the as-constructed drawings. All as-constructed drawings, irrespective of whether there are changes to the srcinal design drawings, shall be certified by consultants and shall include sufficient details, including as-built sewer invert levels. These drawings shall be submitted to the Director General.

w)

Excavation shall not proceed too far ahead of pipe laying to avoid damages from flooding or spoil.

x)

Excavation shalltrench not proceed too collapsing. far ahead of the required trench support placing to avoid wall from

y)

Excavation shall comply with the relevant Occupational Safety and Health Act (OSHA) requirements for safety.

Bored Excavation a)

The bore shall be on the line, level and grade and of sufficient diameter to allow pipes to be inserted without over-stressing the joints or damaging the pipes.

3.4

Pipe Laying

3.4.1

Pipe Bedding

66

a)

Only approved materials are allowed to be used for pipe embedment. They shall be in accordance to the approved longitudinal and cross-sectional sewer profile drawings, which shall also provide details of the designed bedding types.

b)

The bedding material shall be placed as soon as possible after the base of the trench is prepared and excess water has been removed.

c)

Granular bedding shall be placed, compacted and graded so that it offers continuous support to the sewer. The compacting, where required, shall achieve a uniform density.

d)

A small hole shall be left in granular bedding for each socket, jointing sleeve, flange, etc. that may project into the bedding. The holes shall be of size that is just sufficient for projections to be clear of bedding. Long and large holes that may undermine the pipe barrel support are not allowed.

e)

A recess shall be made in the bedding to permit the withdrawal of the sling without disturbing the remaining bedding.

f)

Where the bedding is disturbed, the pipe shall be raised again to repair the bedding.

g)

Pegs or other temporary aids to levelling shall be removed before pipe laying.

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3.4.2

Pipe and Fit tin gs Placement a)

Before lowering the pipes into the trench, pipes shall be placed next to the trench away from the trench edge. The pipes shall be placed on the opposite side of the spoil beside the trench with their sockets facing upstream. Where required, the pipes shall be blocked or chocked to prevent any rolling.

b)

Pipes and fittings (including linings, sheathings and protective paintworks) shall be checked for damage before and after laying in the trench.

c)

VC pipes shall be carefully tapped at mid length and either end with a wooden mallet or, otherwise, a metal bar. This is to detect a clear ring that indicates soundness. This is best undertaken while each pipe is lifted in free air with a lifting sling.

d)

Pipe and fittings shall not be dropped into the trench. Instead, pipes shall be lowered into the trench using approved slings.

e)

Pipes shall be laid from the downstream end towards the upstream end.

f)

The laying of pipes shall proceed carefully to ensure the line, level and grade are within the specified tolerances.

g)

Pipes shall not be dropped or impacted forcefully into the bedding to obtain the specified level or grade.

h)

Concrete pipes with elliptical reinforcement shall be laid with the load line on the vertical axis at the top or bottom position.

i)

Holes made in granular bedding for projections of sockets, flanges, etc. shall be lightly filled where necessary without pushing the pipe/fitting off line, level or grade.

j)

Bedding shall be checked to ensure continuous support along the pipe barrel. Further bedding material shall be placed to an even height and uniformly compacted across the trench to ensure the full support of the pipe haunch.

k)

Pipes that are laid on concrete, grout, cement stabilised bedding or connected to a concrete structure shall consist of a flexible joint at the upstream end immediately outside such a zone.

l)

Pipe level, grade and alignment shall be sighted using sight rails and boning rod or laser and target. They shall be in accordance to the approved longitudinal and cross-sectional sewer profile drawings, which shall be submitted for approval before work at site is allowed to begin.

m)

The invert level of each pipe laid shall be checked during laying and immediately after laying completion, and with reference to the approved drawings.

n)

Boning rods shall have a foot to rest on the pipe invert with a vertical spirit level attached and shall not be more than 45 m apart.

o)

The pipe interior shall be cleaned after laying and kept clean and free of water.

p)

The pipe ends shall be sealed with a tightly fitting plug immediately after laying, cleaning of the pipe interior and at the end of the day after laying.


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q)

The branch arm of the oblique branch junction fitting, if installed, shall be laid in such a way that it is at approximately 45° off horizontal level.

r)

Junction fittings shall be properly supported using well compacted crushed rock (or, where required, concrete). The coverage of the support shall be across to the trench wall and into the junction trench.

s)

Branch connections shall be sealed with an approved plug where connections are to be made at a later time.

t)

Any pipe laid that is out of alignment either vertically or horizontally or shows undue settlement shall be taken up and re-laid correctly.

u)

3.4.3

3.4.4

68

Photographs shall be taken during pipe laying and after sewer pipe laying for all lengths of pipes and manholes.

Pipe Jacking a)

Jacking method of pipe laying shall be employed only when the conditions or the requirements of the responsible authorities require such a method.

b)

The pipes used for jacking shall be able to withstand the laterally induced jacking stresses without damage.

c)

The setting out of the guide rails for the pipe and the actual jacking operation shall maintain a high accuracy level of line and grade.

d)

The direction and grade for jacked sewer shall not deviate from the designed alignment for more than 100 mm for every 100 meters of sewer.

e)

All the joints used for connecting the jacked pipes shall be watertight and durable.

Concrete Pipe Support a)

Concrete used shall be 20 MPa Portland cement concrete with a slump no greater than 80 mm.

b)

When purpose-made pre-cast concrete blocks are used, the block shall have approximately the same width as the trench and shall be positioned just behind each pipe socket. A compressible packer of polystyrene or particle board shall be placed between the pipe and the concrete block.

c)

Concrete shall be poured in one lift.

d)

Pipes shall be prevented from floating or other movement during concrete pouring.

e)

A space shall be left between the concrete supports for the pipe socket by use of a polystyrene spacer of 20 mm minimum thickness. This is to retain rotational flexibility at the joint.

f)

The concrete support shall fit the pipe closely after hardening.

g)

Concrete shall be allowed to cure for at least 7 days before applying any load.

h)

Where the trench base is soft or puddly, a blinding layer shall be placed on the trench base before the concrete is placed.

Volume 3



3.4.5

3.4.6

3.4.6

Pipe Cutting a)

Only VC, HDPE, ABS and DI pipes are permitted to be cut in the field. However prior approval from the Director General is required should the HDPE helically wound profile wall pipe needs to be cut in the field. All pipes shall be cut in accordance to approved methods.

b)

Rough edges and burrs shall be removed from inside and outside of HDPE and ABS pipe with a rasp or file.

c)

Pipes shall be cut in a neat and skilful manner by workers experienced in pipe cutting.

d)

Pipes shall be cut perpendicularly to the pipe axis.

e)

Any damage to the cement lining of DI pipe shall be repaired to the satisfaction of the Commission.

Backfill of Trench a)

Selected excavated material shall be placed above the specified pipe support until 300 mm above the sewer. They shall be in accordance to the approved longitudinal and cross-sectional sewer profile drawings, which also give the bedding details and the types of fill material.

b)

Trench support shall be progressively removed as the backfill is placed.

c)

There shall be at least 300 mm of cover over the sewer before light mechanical compaction can commence.

d)

There shall be at least 1000 mm of cover over the sewer before heavy mechanical compaction can commence.

e)

For plastic pipe, a metallic marker tape shall be laid along the line of the sewer at approximately 500 mm below the surface level.

Other General Requirements a)

Reference shall be made to the approved longitudinal and cross-sectional drawings of sewer profiles of both gravity sewers and force mains. These drawings submitted for approval must include details of bedding types and manhole types, and their design must be must be supported by soil reports.

b)

Pipe laying shall be such that there is adequate access for operations and maintenance of completed sewers, especially in undulating ground profiles, with a minimum width of 6 metres, which shall be supported by drawings with ground profiles during drawings approval stage.

c)

For easy identification of underground forced sewer mains, their layout shall be planted with marker posts at every 200m length and at every change of pipe directions. Valve chambers provided shall have adequate access for operations and maintenance.


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d)

There shall be adequate site supervision of construction, and at least these documents must be submitted before approval of construction:

i. ii. iii. iv. e)

Photographs showing sewer pipe laying during an after construction for all lengths. Testing certificates from the consultants (see Section 4 on Sewer Testing) Supervision certification from the consultants As-built drawings certified by the consultants

The construction and installation works shall incorporate the consideration of health and safety.

3.5

Pipe Jointing

3.5.1

Flexible Joints

70

a)

Joint components (i.e. spigots and sockets or sleeves and rubber seals) shall be checked for damage after delivery, before and after usage.

b)

Every part of the rubber ring shall be bent by hand to detect cracks.

c)

VC pipe sockets shall be gently tapped with a wooden mallet or, otherwise, a metal bar to detect a clear ring that indicates soundness.

d)

Steel sleeve collars used for jacking pipe shall be checked for damage to the coating.

e)

Pipe jointing surfaces and rubber seals shall be wiped clean immediately before jointing using a clean cloth.

f)

The rubber ring shall be placed correctly around the pipe joint.

g)

The rubber ring shall not be twisted in any way prior to jointing and shall be seated in the correct position.

h)

For skid type of joints (i.e. the sealing ring remains stationary and does not roll into place), the spigot shall be lubricated with an approved lubricant.

i)

The pipe to be jointed shall be aligned with the laid sewer before pushing in the joint.

j)

The pipe to be laid shall be orientated so that the offset inside the pipe at the joint is minimise at the invert.

k)

The pipe that is already laid and to be connected to another pipe shall be restrained to prevent its pipe joints being further stressed and to prevent the laid pipe from being pushed off grade or alignment.

l)

Pipe joints shall be connected using a bar and block (crow bar and a block of wood to protect the pipe end) or a pipe puller.

m)

A machine bucket shall only be used to connect a pipe joint where approval is given by the Commission. This method shall only be used for large diameter pipes (larger than 600 diameter pipe) where the jointing compression force makes it impossible to use a bar and block or pipe puller. A timber shall be placed across the pipe end to protect the pipe from

Volume 3



damage. Pressure shall be applied by the bucket gently while the insertion shall be carefully monitored and directed by a person next to the joint. n)

No excessive force shall be applied to make the joint.

o)

After pushing the spigot into the socket, the seal shall be checked to ensure the seal is correctly located and the spigot is properly inserted. No contaminants are allowed between jointing surfaces. The joint or pipe shall not have damage from jointing.

p)

Any allowable deflections at joints shall only be made after the pipe jointing is made.

q)

3.5.2

Where a pipe is to be deflected at a joint, the deflection shall not exceed the allowable limit for the specific type of joint.

Solvent W eld J oints a)

The socket and spigot shall be checked for damage before and after jointing.

b)

Damaged spigot ends shall be cut from the pipe with 100 mm clearance to the damage. The spigot end shall be cut perpendicularly to the pipe and any burrs shall be removed.

c)

The spigot shall be inserted up to the witness mark.

d)

If a witness mark is not already on the pipe, the mark shall be made to ensure that the spigot is inserted to the appropriate length.

e)

Witness marks drawn on site shall be made with a soft pencil or felt pen

f)

marker that would not score or scratch the pipe. The witness mark shall be of the depth of the socket and shall be measured from the pipe end.

g)

A dry fit of the joint shall be made before the jointing.

h)

Jointing surfaces shall be wiped clean and dried with a clean cloth.

i)

Jointing surfaces shall be primed using an approved priming solution. The priming shall be applied with a clean cloth or swab freshly dipped in the fluid immediately before jointing.

j)

A thin and even coat of solvent cement shall be applied to the socket and the spigot, which should then be inserted up to the witness mark.

k)

The jointing surfaces shall not be contaminated with water, dirt, etc.

l)

The jointing shall be made immediately after the application of solvent cement.

m)

After the position spigot isfor pushed into the socket, the joint shall be hold in the same at leastfirmly 30 seconds without moving.

n)

The jointed pipes shall not be moved for at least 5 minutes after jointing. The jointed pipes shall be handled with extreme care for at least another hour.

o)

Joints shall be left to dry for at least 24 hours before pressure testing.


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3.5.3

3.5.4

72

p)

Containers of solvent cement and primer shall be kept tightly sealed when not in use.

q)

Solvent cement and priming fluid are highly flammable. Therefore, the solutions shall be stored in a cool place away from any source of spark or fire.

Flanged Joints a)

Flanges, particularly flange faces and rubber seal shall be checked for damage before and after jointing.

b)

Appropriate metal backing plates shall be used on plastic flanged pipe.

c)

Screwed-on flanges shall have the screw thread sealed with a compound suitable for sewers.

d)

Flanged ends shall be correctly aligned before jointing.

e)

A steel bar or similar object shall not be used as a lever through the flange holes to bring the bolt holes into line prior to bolting.

f)

The rubber seal between flanges shall be made of an approved compound and shall meet the specified requirements.

g)

The flange faces and the rubber seal shall be wiped clean with a cloth immediately before jointing.

h)

Bolts shall be tightened evenly and gradually in rotation.

i)

Bolts and nuts shall be tightened with a torque trench set at an appropriate torque.

j)

Plastic flanges shall not be distorted before or after jointing.

k)

After pressure testing, metal flanges shall be reprimed and painted with two coats of bituminous based coating in accordance with BS 4147 for below ground protection.

Steel Pip e Weld ed Jo in ts (Field Weld in g) a)

The welded joint shall use a socket-spigot joint with taper sleeve wherever possible.

b)

Welding surfaces shall be cleaned to a bright metallic finish before welding.

c)

Welders shall be qualified in accordance with the requirements of British Standard BS 4515 Specification for welding of steel pipelines on land and offshore.

d)

Welding procedures shall be tested, qualified and approved in accordance with BS 4515.

e)

Welds shall be inspected and tested in accordance with BS 4515.

f)

After welding, exposed external surfaces shall be cleaned by sand blasting or wire brushing. The dry surfaces shall be wrapped in an approved manner with an approved wrapping tape to provide corrosion resistance.

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3.5.5

Poly eth ylene Bu tt Weld ed Jo in ts a)

The pipes to be joined shall be of the same grade of polyethylene and of the same wall thickness.

b)

The butt welding machine shall be of an approved type and shall be fit for use.

c)

The welding machine shall be sheltered from wind and rain during the welding process.

d)

A practice weld shall be performed and discarded to check the operational effectiveness of the machine.

e)

The pipe ends shall be trimmed square.

f)

The ends to be jointed shall be kept free of dirt, grease and moisture after trimming.

g)

The heating plate shall be brought into contact with the pipe ends only after it is at the correct temperature.

h)

The pipe ends shall be held against the heating plate for the specified time appropriate for that pipe size.

i)

Immediately after the removal of the heating plate (no longer than 15 seconds after heating), the pipe ends shall be pressed together with an appropriate pressure for a specified time appropriate for that pipe size.

j)

The joint shall be maintained clamped and pressurised in the machine for a suitable period of cooling time (approx. 10 minutes minimum).

k)

After removed from the machine, the joint shall not be stressed until it has completely cooled (approx. 10 minutes minimum).

l)

The weld shall not be artificially cooled with cold air or water.

m)

The external bead shall carefully be removed. thoroughly checked.

n)

A pipe end that has undergone a complete heating cycle but not joined shall not be reheated. The unjoined pipe end shall be cut off to at least 250 mm from the end.

3.6

Special Requirements For S ewer

3.6.1

Thr us t Bl oc ks fo r Press ur e Pip eli nes

The joint zone shall be

°

a) b)

The thrust block shall be extended to approximately 180 around the fitting. The thrust block shall not cover a flexible joint.

c)

The thrust block shall be constructed equally around the centreline of the fitting.

d)

The thrust block shall bear firmly against a recess at the side of the trench.

e)

The trench face which the thrust block bears against shall be freshly cut and undisturbed.


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3.6.2

3.6.3

74

f)

Each thrust block shall have sufficient bearing area.

g)

Thrust block shall be cast-in-place with 20 MPa concrete.

h)

For plastic pipe or pipe with a protective coating, a compressible membrane of rubber, felt or cork shall be placed on the pipe to protect it from damage from its movement in the thrust block.

i)

Formwork shall be used to cast the thrust block to the required dimensions.

j)

Formwork shall be removed before any testing.

k)

Reference shall made to the standard drawings for thrust block to ensure proper shape and size, which must be designed for each individual thrust blocks.

Pip e Rest rain ts and Bu lk heads on Steep Slo pes a)

A bulkhead to prevent soil erosion shall be used where the gradient of the sewer is steeper than 1 in 40.

b)

A restraint to prevent sewer slippage shall be used where the gradient of the sewer is steeper than 1 in 6.

c)

The restraint or bulkhead shall be placed at the downstream side of the socket.

d)

Concrete bulkheads shall be keyed into the base and sides of the trench by at least 100 mm.

e)

A weep hole with the upstream end covered with a geotextile filter shall be provided through a bulkhead immediately above pipe invert to allow drainage of groundwater.

Pip e Embedment and Overlay a)

The embedment material type and its grading shall take considerations of the sewer type or length.

b)

Reference shall be made to the approved longitudinal and cross-sectional drawings of the sewers showing the bedding types, which shall be designed based on supporting soil reports.

c)

Embedment material shall not be contaminated with other soils.

d)

Embedment material shall be brought up evenly in layers on each side of the pipe.

e)

Each embedment layer shall be placed to a depth that permits the

f)

compaction equipment to achieve the specified density. The pipe shall not be pushed off alignment, level or grade while placing the embedment.

g)

Where the embedment requires tamping, tamping equipment shall not come into contact with the pipe.

h)

Temporary trench wall support shall be lifted when the embedment is compacted.

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3.6.4

i)

While placing the embedment for the pipe haunches, unnecessarily voided areas shall be avoided.

j)

At least 300 mm of cover shall be placed over the pipe before light mechanical compaction, such as a hand operated whacker, can commence.

Sleeving o f Ductile Iron Pip e a)

Plastic sleeve shall be secured immediately behind the second spigot jointing witness with wrapped three overlapping tape.surplus After that, sleeve shall mark be tightly around theturns pipeof byadhesive folding over sleeving. Then, the sleeving shall be further secured with three winds of overlapping adhesive tape at one meter intervals.

3.6.5

b)

The pipe shall be placed in the trench with the folding of the sleeve located at the top of the pipe.

c)

After the pipe jointing, the sleeve of the preceding pipe shall be brought over to cover the socket and the cover shall follow the socket outer surface closely.

d)

The sleeve of the preceding pipe shall overlap the sleeve of the next pipe. The sleeve overlap shall be secured with three overlapping winds of tape.

‘Roc ker’ Pip e Con nect io ns to Manh oles a)

The ‘rocker’ pipe connecting sewers to manholes shall have sufficient cast insitu concrete surround and extended concrete base as shown in typical manholes drawings in Appendix A.

3.7

Reinstatement a)

All structures, services, fences, drains, gardens, improved surfaces, etc. disturbed by the construction shall be restored within 7 days after backfilling. The restored conditions shall be as similar as possible to their srcinal condition. Also, the condition shall be to the satisfaction of the Commission, other responsible authorities and property owners.

b)

Where a structure or service is affected by construction, the trench fill shall be compacted to the equivalent of that under a pavement.

c)

Within 7 days after backfilling, fill over unimproved surfaces shall be placed to a height that will make the filled surface level and the adjacent undisturbed surfaces closely matching after settlement. All contours shall

d) e)

be similar to the srcinal condition. Unimproved surfaces shall be levelled and settled to as near as possible to their srcinal condition in 30 to 40 days after backfill. Road pavements and access ways shall be temporarily restored to a safe condition, immediately after completion of backfilling. Then, the pavements shall be permanently restored to as similar as possible to their srcinal condition within a time frame specified by the responsible authority.


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f)

Extra excavated material, un-reusable excavated material and all rubbish shall be removed from the site and legally disposed of.

3.8

Connections to Public Sewers

3.8.1

General Severe maintenance problems are often caused by poorly made connections to sewers. These may lead to blockages or failure of the sewer structurally. The following procedures and formalities must be followed to ensure integrity of the sewerage system. a)

The owner must seek the approval of the Director General for any connections that involve physical work to an existing public sewer. The initial notification must be made on the appropriate form.

b)

Once approved, the owner may make the connection only if his contractor is licensed by the Commission for this category of work.

c)

The type and location of connections shall be determined by the Commission. The type of connection could be a connection to a manhole or a connection to a sewer through junction or saddle fittings.

d)

The cost of the work in making the connection shall be borne by the owner, regardless of whether the work is undertaken by his licensed contractor or a

e)

76

licensed contractor employed by Services Licensee. The connection must be correctly made by the licensed contractor under the supervision of an authorised inspection person.

f)

When the connection is ready for inspection, the owner must notify the Commission on the appropriate form. At the same time, he must give a copy of the notice to the authorised inspection person who will make arrangements for the inspection.

g)

The connection must be completely watertight to prevent infiltration. Any evidence of infiltration in the connection pipe shall be referred to the Local Authority who may withhold issuing the Certificate of Fitness.

h)

For a development which contains several connections from individual premises to the proposed public sewers within the development, the connections may be deemed covered by the srcinal technical proposals. These individual connections will be inspected as part of the routine inspection by the authorised inspection person.

i)

The inspection by the authorised inspection person for the connections to existing public sewers shall be subjected to a standard inspection fee.

j)

The design and installations shall incorporate the considerations of health and safety

k)

The difference between each premise platform level and the nearest public sewer invert level shall not be less than 1.2 metres to avoid flooding of premises.

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3.8.2

Junction C onnections Where an existing public sewer is circular and is of diameter DN 450 or less, any connection to that sewer may be made using a Y junction fitting. Where the location of future connections are known, Y Junction fittings and the accompanying junction connection pipework may be installed at the time of the public sewer construction. The connection configuration of junction is shown in Figures A.11 and A.12typical of Appendix A. Where no junction pipework exists, a Y junction fitting may be installed by removing part of the existing sewer. The connection of such a junction shall use flexible couplings.

3.8.3

Saddle Connections Saddle connections may only be permitted where the existing sewer is at least two pipe sizes greater than the proposed connection pipe. Only saddles specifically designed for the type and size of the sewer to be connected to shall be used. Also, the saddle used shall be approved by the Commission. Making a saddle connection is a highly skilled operation. Hence, only licensed contractors who can demonstrate suitable qualifications and experience are permitted to make this form of connection. The saddle must be purpose-made by off-site manufacture except when the existing pipe size is 900 mm in diameter or greater, which other forms of connection are preferred. The saddles for concrete or vitrified clay sewers shall be bedded on cement mortar (mix 3:1) with a depth not less than 40 mm below the base of the saddle. A flexible joint shall be provided between the saddle and the remaining connection pipe. The hole prepared for the saddle connection on the existing sewer shall not have any rough edges that might cause blockage. The location of the hole on the pipe shall be at a 45° to 60° angle to the horizontal. The hole shall be made at the middle of the pipe to avoid damages or excessive loading to the existing sewer pipe joints. The existing pipe may require extra strengthening by additional concrete surround to withstand the extra load from the connection pipe and fittings. The connection pipe must not protrude into the existing sewer. Any debris falling into the existing sewer during the connection shall be removed. On completion, the saddle connection joint must be completely watertight to prevent infiltration.


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3.8.4

Manhol e Connec ti ons Manholes may be constructed on the public sewer for private sewer connections where: a)

good practice requires a manhole for ease of maintenance, or

b)

the diameter of the connection pipe is 300 mm or greater, or

c) d)

the public sewer is more than 4.5 m deep, or the point of connection is more than 5 m from an existing or proposed manhole.

Where site conditions prevent manhole construction on the existing public sewer, the manhole may be provided on the connection pipe as near to the public sewer as possible.

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Secti on 4 Sewer Test in g

Sewer Testing

4.1

General Sewers and ancillary works shall be tested and inspected for water-tightness to prevent infiltration and exfiltration and to ensure the pipe are laid correctly according to the designed straightness and grade. The testing of the sewers and ancillary works before backfill will facilitate the replacement of any identified faulty pipes and joints. The testing of the sewers and ancillary works after backfill will reveal the leakages caused by the displacement of joints and subsequent damage. The testing shall be supervised by consultants and their testing certificates issued by the consultants shall be submitted to the Commission before final approval. The tests that are required to be conducted are listed as follows:

I) a)

b)

c)

Before Backfi ll Gravity Sewer:

i.

Exfiltration Test (Either low pressure air or water tests)

ii.

Check for straightness, obstruction and grade

Force Main:

i.

Exfiltration Test (When required)

ii.

High pressure water test

iii.

High pressure leakage test (Following high pressure water test)

iv.

Check for straightness, obstruction and grade

Manhole and others:

i.

Visual inspection

ii.

Water-tightness test (when required)

To prevent movement of the sewer, embedment material shall be placed around and over the sewer prior to testing. The section of the joints above spring line shall be exposed. For pipe or part that is made of material that will deteriorate under the sun, the exposed parts of the pipe shall be shielded from direct exposure to the sun during testing. The concrete used for supporting the pipe or resisting thrust shall be cured for at least seven days prior to testing.


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Sewer Testing

II)

After Backfill

a)

Gravity Sewer:

i)

Exfiltration Test (Either low pressure air or water tests)

ii)

Infiltration Test (when required)

iii)

CCTV Test (when required)

Before and clean after any test,necessary. the sewer pipeline to be shall be clean, which be flushed when Any leaks or tested defects identified from anyshall test shall be located and repaired. After testing has been completed, the cleaned sewer shall be plugged at open ends to prevent dirt or soil from getting into the sewer.

4.2

Testing of Gravity Sewers The tests of gravity sewers are generally conducted to ensure there is no leaks, damages, or laying errors. An exfiltration test, which can be either a low pressure air test or a water test shall be performed on the sewer before any concrete pipe encasement or backfill. After backfilling, an exfiltration test is required again on the sewer laid. In addition, an infiltration test shall be conducted if: a)

required by the Commission

b)

detected high groundwater table

When infiltration has been confirmed by the infiltration test, light and mirror method or CCTV may be used to isolate the locations of leaks. If a CCTV inspection is conducted, a video and written record of the CCTV inspection shall be provided to the Commission no later than 7 days after the inspection. For gravity sewers, the sewer length to be tested shall be the length between manholes or proposed manhole locations. The test length for water test may be shorter where the gradient is so steep as to cause too high a head at the downstream end. The pressure head on the sewer being tested shall not be less than 2 m above pipe crown at the upstream end and shall not be more than 7 m above pipe crown at the downstream end. When desired, the air and water tests may be undertaken on shorter lengths of the laid sewer before backfill. This is to prevent any faulty joint to go unnoticed until it is revealed a testthe ondefects. the complete length, whichlengths will bemay more costly and time consuming toby rectify Testing of shorter also be necessary where it is required to backfill the sewer to surface level quickly. This early backfill may be encountered when there is wet weather, traffic crossings or site safety requirements. In every stage of the works, frequent tests of straightness and obstruction shall be conducted, when required, to ensure there is no line obstruction and the straightness or grade is correct.

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4.3

Testing of Forced Mains For pressure sewers, the normal tests during the sewer laying may include, where required, the low pressure air or water exfiltration tests on short individual sections. These low pressure air or water exfiltration test are conducted, when required, to ensure that the joints are watertight. As in gravity sewers, the force mains should be checked to ensure the straightness is correct and to ensure no obstruction in the force mains. Also, force main is required to be tested for its mechanical stability through the high pressure water test. Its water-tightness shall be tested through high pressure exfiltration test. Before conducting these high pressure tests, the sewer support and thrust block shall be allowed to develop the sufficient strength. In addition, cautions shall be taken when dealing with high pressure. Where required, a CCTV inspection should be performed on the pipeline after backfilling the trench. If a CCTV inspection is performed, a video and written record of the CCTV inspection shall be provided to the Commission no later than 7 days after the inspection. For the high pressure water test, the test length will depend on:

a)

the length which can be isolated effectively, i.e. suitable anchorage for temporary end closures

b)

the time permitted to leave the trench open without backfill taking considerations of weather, safety, traffic etc.

c)

the location of permanent anchorages

d)

the maximum volume of water available to fill the pipeline

e)

the requirement to have the pressure at the highest point not less than 0.8 times the pressure at the lowest point

After taking the above considerations, initially a maximum of 300 m length of pipe shall be laid and tested to verify that pipe laying practices are to an acceptable standard. The maximum lengths for subsequent tests may be progressively increased, as determined by the authorised inspection person, but shall not exceed 1500 m.

4.4

Test in g of Manh ol e and ot her anc ill ari es Manhole and other ancillaries shall be constructed in such a way that no appreciable amount of infiltration or exfiltration will occur. When the manhole and other ancillaries are constructed in an effective manner, visual inspection is normally sufficient. However, manholes and other ancillaries suspected of very poor workmanship shall be tested with exfiltration test before backfill or concrete surrounded.


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Sewer Testing

Connections between sewer and manholes shall be constructed with extended castin-site concrete base and surround over the top of the rocker pipe in accordance to the standard drawing attached. Drop manholes shall be constructed in such a way that no appreciable amount of blockage will occur with construction details as in the standard drawings which provide for proper pipe outlets and proper sizing of drop pipes. A visual inspection is required on all the external and internal sections of each manhole before backfill. Particular attention shall be given to:

a)

the slope of benching,

b)

joints to pipes,

c)

transitions at entry and exits,

d)

joints in the structure

e)

quality of concrete finish

f)

water-tightness of manhole cover and surround.

The internal surfaces of manholes shall be inspected visually for sources of infiltration after backfill and stabilisation of groundwater table. Manhole covers and surrounds shall be checked for leakage of surface water.

4.5

Low Pressure Air Test

4.5.1

General Low pressure air test is one of the two sewer exfiltration tests recommended for sewer testing. The air test is quicker to conduct than the water test. Furthermore, no large quantity of water needed to be disposed of after the test. This test provides a quick mean for checking any damage pipe or joints. Sometimes the test is conducted on a short length to prevent damage pipe or joints from passing without noticed until the final sewer test, which could be more costly and time consuming to rectify. However, these tests on the shorter length should not replace the final test.

4.5.2

Procedure for T esting a)

Seal the open ends, including sideline ends, using approved plugs. Strut the plugs to prevent movement. Provide temporary bracing where necessary to prevent pipeline movement during testing. (One of the end plugs will require a connection point to permit injection of air.)

b)

82

Connect a hand or motorised pump to the pressure injection line at the end plug. Pressurise the test length at a slow and constant rate.

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Sewer Testing

c)

Use dial pressure gauges to measure pressure. Apply an air pressure of:

i.

30 kPa for vitrified clay and reinforced concrete pipelines

ii.

50 kPa for all other pipelines

(Two gauges in series shall be used so that the accuracy of one gauge can be confirmed by the other. The dial gauges shall be able to be read to an accuracy of ± 0.1 kPa.)

d)

Wait five minutes for air pressure to stabilise due to temperature absorption into pipe wall and other effects. Adjust the pressure to the required test pressure during this period.

e)

Check for leaks at plugs and test apparatus. Release the air pressure where leakage occurs. Make necessary repairs and adjustments of apparatus to prevent leakages. Repressurise the sewer pipeline in accordance with the preceding steps again.

f)

Start the test and record the pressure loss for the test duration after the final gauge adjustment to the test pressure. Conduct the test for the test duration given in Table 4.1.

Table 4.1 Test Dura tion Pipeline Nominal Size

g)

150 225

2 4

300

6

375

8

450

11

525

14

600

17

Pass the test if the pressure loss over the test duration does not exceed: i) ii)

4.5.3

Test Duration (minutes)

7 kPa for vitrified clay and reinforced concrete pipes 2 kPa for all other pipes

Pro cedu res f or Hand li ng Ai r Test Fail ur e I)

Before Backfill

a)

Readjust the pipe pressure to the specified test pressure and examine for leakage by pouring a solution of soft soap and water over the exposed joints if the test fail.

b)

Repair leaks and repeat testing where leaks are found at joints.


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Sewer Testing

c)

Where leaks are not found at joints, move the plug, the one that is not used to exert air pressure, along the pipeline to isolate lengths with leakage. Uncover pipe barrels in the isolated lengths where leakage in pipe barrels is suspected. Replace leaking pipe lengths and repeat testing.

d)

Conduct low pressure water testing to verify that the air test was not erroneous where the test length fails the air test but no source of leakage can be identified.

II)

After B ackfilling:

a)

Move the plug up from the other end along the sewer pipeline to isolate the lengths that fail the air test.

b)

Exhume the failed length of pipeline and replace pipe lengths.

c)

Repeat the air test.

d)

Conduct water testing to check that the air test was not erroneous when failed lengths could not be isolated using the air test.

e)

Use CCTV, when required or available, to identify the leakage if the fail section can not be isolated by the air test or water test.

4.6

Low Pressure Water Test

4.6.1

General The low pressure water test is commonly used for checking the water-tightness of the joints and the integrity of the sewer pipes. Unlike the high pressure water test, this test can not be used to check the mechanical strength of the sewer pipe. Compared with low pressure air test, this test requires more time to set up the test. Also, the water used for the test require disposal in an appropriate manner. However, this test will show the location of the leaks more clearly than the low pressure air test.

4.6.2

Procedure a)

Seal the open ends, including sideline ends, using approved plugs. Strut the plugs to prevent movement. Provide temporary bracing where necessary to prevent sewer movement during testing.

b)

Establish appropriate arrangements involving a standpipe to apply the water head at the upstream end. (Acceptable arrangements include:

i.

84

temporarily fitting a 90° bend to the upstream end, which should then be connected with a vertical riser of straight pipe to used as a standpipe

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Sewer Testing

ii.

sealing the upstream end with a plug which has a connection point for a hose, which can be connected to a tube acting as a standpipe)

d)

Fill in water from the upstream end. Ensure water head is not less than 2 m above pipe crown at the upstream end and not greater than 7 m above pipe crown at the downstream end. Shorten the test length if the sewer gradient is so steep as to cause these water head requirements not to be met.

e)

Fill the sewer slowly to the required head and bleed air from behind the upstream plugs. (Air may be released by slightly loosening the plug and pushing in a piece of wire between the seal and the pipe.)

4.6.3

f)

Maintain the water head for two hours. Top up the water as required.

g)

Check for leakage at the plugs and the test apparatus during the pressurising period and the constant pressure holding period. Release the water pressure if leakage occurs. Make the necessary repairs and adjustments before repressurising again.

h)

Commence the test immediately after the last adjustment of water head in the preceding two hours period.

i)

Add water to maintain the starting water head every 5 minutes during the test period of 30 minutes. Record the total amount of water required for readjustment.

j)

Pass the water test if:

i.

the lossinternal of waterdiameter does not for exceed 1 litreclay per hour per linear metre per metre vitrified and reinforced concrete pipes,

ii.

there is no loss of water for pipe other than vitrified clay and reinforced concrete pipe,

iii.

these is no visible leakage at the joints for all pipe types.

Hand li ng Water Test Fail ur es I)

Before Backfill:

a)

Readjust the internal water head to the specified test head if the test section fails the water test. Examine visually for leakage at the external surface of joints.

b)

Uncover pipe barrels and inspect for leakage if leakage is not evident at joints. Drain the water and move the downstream plug towards upstream, where necessary, to isolate pipe lengths that fail the water test.

c)

Repair or replace pipes before repeating the low pressure water test until the sewer passes the test.


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Sewer Testing

II)

After Backfill:

a)

Isolate pipe lengths that fail the water test by moving the downstream plug towards the upstream end in sections when the test sewer fails the water test. Alternatively, conduct a CCTV inspection, where required, to identify the source of leakage if the source of leakage can not be isolated.

b)

Exhume failed pipe lengths and replace.

c)

Repeat test until the sewer pipeline passes the test.

4.7

High Pressure Water Test

4.7.1

General High pressure water test is normally used for testing the pressure sewers and pipe works within the pump station. The main aims of the test are to ensure the mechanical stability of the pipe and joints to withstand the working pressure. Since the test is conducted under high pressure, the anchorage of the sewer is more critical than the low pressure tests. Preferably, the test should be conducted before backfill. During the test, the test pumps should not be subjected to hydrostatic pressure.

4.7.2

Procedure a)

Seal theofsewer pipeline ends using units Connected consisting the of “testshort lengths pipe permanently fitted with“test-end” caps or valves. end” units to the test pipe section using a standard coupling, which permits easy removal of “test-end” units after testing. (The “test-end” units should have a valve with pressure gauge to allow filling of the test length with water or for venting air. The gauge shall be a conventional circular gauge not less than 200 mm diameter and shall be able to read to an accuracy of ± 0.01 Mpa.)

b)

For sewer on level grade, fit tees along the test length, where necessary, to ensure all the air can escape. Fit air valves to such tees. Remove air valves and blank off tees after the test is applied.

c)

Fit the test pressure gauge at the lowest end of the test length. (This prevents the test pressure from exceeding the permitted maximum pressure in the test length.)

d)

Place pre-constructed temporary thrust blocks behind the test end units to brace against thrust from the test pressures. (No temporary bracing is permitted along the sewer pipeline. All specified thrust blocks must be constructed and left to cure before testing.)

e)

86

Fill the test length slowly with water through the valve at the lowest testend unit.

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Sewer Testing

(The water shall be of fair quality and free from sediment. A firm foam swab placed ahead of the water column will improve the expulsion of air.)

f)

Set all valves at high spots to vent air.

g)

Close the air vents after thorough venting of all air.

h)

Fill the test length with water. Leave the filled test length undisturbed for 24 hours prior to testing to allow for absorption of water into the pipes and /or jointing materials.

i)

Wipe the exposed fittings and joints clean and dry and check for leakage and other irregularities during this preparatory period. Check also the test pipe for any appreciable movement and disturbance of anchorages. Drain the water and repair any damage found. Repeat the water filling again to start the test.

j)

Pump more water into the test length to raise the pressure. Raise the pressure slowly in increments of 1 bars, with pauses of one minute between each increment until achieving the lower of:

i.

the maximum rated pressure of the pipes laid, or

ii.

1.5 times the design operating pressure of the pipeline (includes surge allowance)

k)

Stop the test immediately should any appreciable drop in pressure be noted during one of these pauses. Determine the cause of the pressure drop. Drain the test length where repairs are required. Start the test again after repairing.

l)

Pass the pressure test if there is no reduction from the test pressure in the next 10 minutes after the test pressure is achieved. Do not reduce the pressure since the high pressure leakage test should be conducted immediately next.

4.8

High Pressure Leakage Test

4.8.1

General High pressure leakage test normally follows the high pressure water test immediately. This is to avoid any unnecessary pressurising and water filling, which could take time and is costly. The purpose of this test is to ensure the pipe and joint will remain intact under the pressure environment.

4.8.2

Procedure a)

Conduct the test immediately after the high pressure water test. Maintain the following test pressures (whichever is lower) for 24 hours by pumping in make-up water if necessary:

i.

the maximum rated pressure of the pipes laid, or

ii.

1.5 times the design operating pressure of the pipeline (includes surge allowance)


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Sewer Testing

4.9

b)

Measure the amount of make-up water pumped into the pipe to maintain the test pressure.

c)

Pass the test if the measured amount of make-up water does not exceed 0.1 litre per millimetre of pipe diameter per kilometre of pipe per day for each 3 bars of pressure applied.

d)

Reset the test pressure and check all visible joints to locate leakage when the test length fails the test.

Test fo r Str aigh tn ess , Obst ru ct io n, and Grade The sewers shall be check for straightness, obstruction, and grade whenever possible. For gravity sewers and force mains, the grade and straightness are important to achieve the designed velocity. The following tests are recommended for testing the laid sewer:

I)

Test fo r fr eedo m fr om obs tr uc ti on:

a)

Visual inspection

b)

Insertion of mandrel

c)

CCTV inspection

It should be noted that the visual inspection is only for checking a short length. Sufficient light shall be provided when carrying out the inspection. For checking a long sewer, insertion of a mandrel should be adopted.

II)

Test fo r g rade and st raig ht ness

a)

Laser beams with sighting targets

b)

Sight rails and boning rods

c)

CCTV inspection

d)

lamp and mirrors

e)

Insertion of a smooth balls

The first three methods will provide a more exact assurance for both the grade and straightness of sewers, which shall be used whenever possible. The latter two methods will provide a rough ideas on whether the sewers are laid graded or straight, which should be used only for a quick check.

4.10

CCTV Inspection The following subsections outline details on how the CCTV inspection requirements shall be implemented. These guidelines are also aim to enhance professionalism in line with progress in sewerage field, and promote efficiency and

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Sewer Testing

cost effectiveness as well as transparency and accountability in sewerage system development.

4.10.1

4.10.2

Obj ect iv es of CCTV Ins pect io n a)

Enable detection of sewer defects such as cracks, deforms, collapse, dislocate and etc. which are not detected by normal means;

b)

As a quality assurance measure to ensure sewers and sewer appurtenances are constructed in conformability with approved design, specifications, workmanship as well as materials and fixtures used;

c)

As a means to establish record to enhance accountability professionalism on quality assurance for sewer construction.

and

Techn ica l Requi rements a nd R eference s a)

Analysis of defects shall be based on WRc Manual for Sewer Condition Classification Latest Edition;

b)

Equipment and test devices to be used are as listed in Section 4.10.3.

c)

For sewer with diameter larger than 1050 mm, Man-entry CCTV survey mode may be adopted unless it can be demonstrated that the CCTV can be maintained in a stable position on or near the central axis of the sewer and images captured are satisfactory and not distorted.

4.10.3

Equi pme nt S pecifi catio ns a nd T est D evic es

4.10.3.1

Spec ifications for C CTV unit’s e quipme nt a.

Solid state colours CCTV camera with pan & rotate features, together with a lighting unit, automatic date/ metre age.

b.

A self powered tractor or crawler on which the camera is conveyed along a pipeline under inspection in a stable manner.

c.

Calibration chart for various sizes of sewer for the camera used.

d.

Test device for the CCTV camera using 'Marconi Resolution Chart No.1' or its derivative to demonstrate satisfactory performance of the camera.

e.

Test device for the monitor and video recorder to establish the effectiveness and accuracy of the 'on-site' monitor and video recorder.

f.

The control unit comprises the camera unit, crawler control and screenwriter. This console can be mounted permanently in a vehicle or use as portable system.

g.

A video recorder for recording high quality video images.

h.

A means of producing still images from the monitor screen.


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Sewer Testing

i.

4.10.3.2

A PC-based site reporting system capable of producing reports customized to the Contractor's needs and to include photographs captured directly from video.

Soft ware Requir ements Software standardisation using databank software that can produce report, based on WRc format.

4.10.3.3

Repor t Form at Report in VCD or other digital form to be submitted in MPEG format with minimum 352x240 pixels. Two copies of digital records and one copy of hardcopy report shall be forwarded to JPP office.

a)

4.10.4.

For the diameter pipe greater than 600mm, it shall have zooming capabilities.

CCTV Insp ecti on R equi rements The following areas area identified as the minimum coverage for CCTV inspection.

4.10.4.1

Hig h Ris k A reas A 100% CCTV inspection shall be conducted for sewers laid in the ground with high risk of failure and having the following characteristics:

4.10.4.2

a)

Deeper than average 6m or more

b)

Pipe diameter above 600mm.

c)

Areas that have restricted vehicular access for repair (e.g. central business district).

d)

Crossings under buildings, lakes, rivers, roads and railway including their reserve.

e)

Ground slopes greater than 30o inclination.

f)

All sewers installed using pipe jacking method.

g)

All diversion or re-alignment of existing sewer networks.

h)

All single private developments (with PE > 30), connecting to existing main sewer.

Genera l Inspe ction Cove rage (for S ewer, Manhole s and La tera l Connections) a)

90

Initial CCTV testing & inspection shall be conducted for a minimum 10% random selection of sewers including all manholes and lateral property connections in accordance with standard procedure.

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Sewer Testing

b)

If the mandatory requirement of Clause 4.10.4.1 is less than 5% of the entire development area, the minimum CCTV testing & inspection is 10% as in Clause 4.10.4.2a. If the mandatory requirements of Clause 4.10.4.1 is more than 5%, the minimum CCTV testing & inspection shall have an additional of 10%.

c)

Prior to taking over existing network that has been approved from any owner or after rehabilitation works have been completed.

d)

4.10.4.3

All new network undergoing intermediate inspection except:

i.

Single Phase development with total sewer length less than 500m long with no interval.

ii.

Vacuum sewer.

Stage of Insp ecti on a)

Stage 1- All projects are to start with stage 1 inspection where 10 % (by length) of sewer network and property connections involved, shall be randomly selected and CCTV inspected.

b)

Stage 2 - Should any Grade 3,4 or 5 conditions as defined in the Manual for Sewer Condition Classification approve by the Commission, found in Stage 1 inspection, the CCTV inspection shall proceed to Stage 2 inspection. Stage 2 inspections shall include another 40% of the sewer network to be randomly selected for CCTV inspection.

c)

Stage 3- Should any Grade 3,4 or 5 conditions as defined in the Manual for Sewer condition classification approve by the Commission, found in Stage 2 inspection, the CCTV inspection shall proceed to Stage 3 where all the remaining network shall be CCTV inspected.

4.10.5

CCTV Inspe ction I mple menta tion P roce dure for N ew Sewer Network

4.10.5.1.

Activities to be comple ted Intermediate Inspection.

4.10.5.2.

before

submitting

for

fina l

a)

All construction works have been completed and tested by the supervising qualified person.

b)

Sewer networks have been cleared of debris and are ready for inspection.

c)

A CCTV to Inspection licensed with the Commission has been appointed carry out Contractor the inspection.

Random selection of sewer to be insp ected. a)

The list of sewer segments and house connections selected for CCTV inspection shall be recorded and the parties witnessing the selection process shall duly sign the record.


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4.10.5.3.

4.10.5.4.

b)

Names and designations of all persons involved in the random selection process as well as the time, date and place where the selection were carried out shall be recorded in the report on the random selection process. Record of the sewer segments randomly selected for CCTV inspection shall be included as appendix to the report.

c)

The random selection process shall be completed in a single session.

CCTV in spect io n on si te. a)

The CCTV inspection shall be carried out 7 days after notice issued by the Commission.

b)

Inspection shall be carried out in within 24 hours after random selection has been completed.

c)

Once started, CCTV inspection for a project shall be carried out without any break. Should for any reason a break/delay of more than 24 hours become necessary, the random selection process shall be repeated to select the remaining sewer segments for the inspection. Reasons for the break/delay shall be recorded.

d)

Representative from the Commission or authorized person, consultant representative and contractor responsible for the construction of the sewer shall be present at the onset of CCTV inspection at each project site.

Docume ntation on CCTV reco rding a)

At the start of the CCTV recording, the following details must be recorded:

i.

Date and starting time of inspection.

ii.

Project name and location

iii.

Names and designation of persons involved (i.e representative of the Commission or authorized person, consultant & contractor and CCTV contractor).

b)

At the beginning of each CCTV recording for every segment of sewer shall be marked with their respective code number with chainage together with the date, start and end times of the recording.

c)

After the CCTV inspection and recording have been completed for a project, a copy of recorded CCTV shall be handover to the Commission or authorized person immediately. Report on the CCTV inspection together with the recording and recommendations shall be prepared by the CCTV contractor andagency submitted to thethan relevant theafter Commission officeThe or the appointed not more 7 days the date ofbranch inspection. format of reporting shall follow the standard that had been given (Appendix C). The copy of the tape (or other recording media used to store the record) containing the CCTV inspection records shall be submitted to the Commission Branch office or the appointed agency together with a certificate duly signed by the qualified person responsible for the CCTV inspection declaring the authenticity of the recording submitted and that the

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CCTV inspection has been done in accordance with the procedure stated in this guideline.

4.10.6

Interpretatio n of Result s fro m CCTV Inspectio n a)

4.10.7

Classification : Grade 1 to Grade 5 as per the Commission approve Sewer Assessment Classification. Colour to show the defect grade description shall be follow as:

i. ii.

Grade 1: Green Grade 2 : Blue

iii.

Grade 3 : Orange

iv.

Grade 4 : Brown

v.

Grade 5 : Red

b)

Grade 1 and 2 is acceptable constructional defects but may have other minor defects. It can be accepted provided a performance bond has been submitted and the contractor undertake to rectify the defect within 30 days.

c)

Sewer with Grade 3, 4 or 5 conditions has major structural defects and shall be accepted. Relaid of the affected sewer segments is necessary.

Fol lo w -Up A ct io n t o B e Taken a)

For Grade 1 and Grade 2, the developer shall rectify and make good to all the defects in 30 days. These rectification works shall be witnessed by the parties concerned and agreed together that the works had been completed. The Commission or the authorised person may instruct CCTV inspection to be carried out again. Under these grade classifications, the letter of recommendation for CFO will be released by the Commission or the authorised agency.

b)

For Grade 3, 4 or 5 classifications, the developer shall change, replace, relay or reconstruct the rejected works. Further CCTV inspection shall be carried out before acceptance. The letter of support for CFO will be released upon acceptance.

c)

In the events of any blockages, damages, seepages and etc to the sewer networks during the defects liability period, JPP may require the developer to carry out further CCTV inspection to determine the cause and extent of the problems that arises. CCTV inspection shall be carried out immediately within 24 hours.

Table 4.1 provides the description of various defect grades


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Table 4 .2 Defect Gra des D escriptions

Grade 1

Occurances without damage and no cracks of pipe but only acceptable displacement on joint where no visual infiltration can be observe: e.g.

Grade 2

Constructional and sewer product deficiencies or occurances with insignificant influence to tightness, hydraulic or static pressure of pipe, etc. Examples: Joint displaced large; badly torched intakes; minor deformation of plastic pipes (<5%); minor erosions; infiltration seeping; Cracks – joint, circumference, longitudinal; Debis, silt – 15%; Encrustation light.

Grade 3

Constructional, operational and maintenance deficiencies diminishing static, hydraulic, safety and tightness. Examples: Infiltration dripping. (OMD); Open joint; untorched intakes; cracks; minor drainage obstructions such as calcide build ups; protruding laterals; minor damages to pipe wall; individual root penetrations; corroded pipe wall; flexible pipe deformation (>5%); Lining defect.

Grade 4

Constructional and structural damages with no sufficient static safety, hydraulic or tightness. Examples: axial/radial pipebursts; visually noticeable infiltration/exfiltration; cavities in pipe-wall; severe protruding; laterals severe root penetrations; severe corrosion of pipe wall; Infiltration running; encrustation medium; minor deformation; flexible pipe deformation >15%

Grade 5

Major structural damaged where pipe is already or will shortly be impermeable. Examples: collapsed or collapsed eminent; major deformation; deeply rooted pipe; any drainage obstructions; pipe loses water or danger of backwater in basements etc

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4.11

Infiltration Test

4.11.1

General Infiltration is an extraneous flow not contributed from households. Although design has allowed for certain amount of infiltration, a significant amount of unexpected infiltration will overload both the collection sewers and the treatment plant. To avoid any extra infiltration, a test maybe conducted on the gravity sewer laid. If the force main is significantly below the groundwater table, an infiltration test is also highly recommended. When severe infiltration is found during sewer laying, the source shall be investigated immediately. Infiltration test is normally conducted after backfill and after the groundwater level has stabilised. The procedures are as follows:

4.11.2

4.11.3

Procedure a)

Plug the inlets at all upstream open ends, after the groundwater level has stabilised following backfilling.

b)

Measure any infiltration from the sewer to the manhole or within manhole itself.

c)

Conduct the measurement of infiltration for at least 24 hours.

d)

Pass the infiltration test if the infiltration does not exceed 1 litre per hour per metre diameter per meter of pipe run.

Hand li ng Test Fail ur es a)

Conduct a light and mirror test to identify the location of the infiltration if the pipe is small and short.

b)

Move an inflated rubber plug toward downstream end to isolate lengths of leakage. Repeat the test procedure after each plug relocation

c)

Conduct a CCTV inspection if the location of the infiltration can not be identified by the light and mirror test or moving the inflated rubber plug.

d)

Exhume and repair the fail section of the pipe.

4.12

Water-tightness Test

4.12.1

General Visual inspection is usually sufficient to ensure the water-tightness of manhole and other ancillary structures. However, water-tightness test may be required if: a)

Instruction from the authorised inspection person

b)

Unsatisfactory features identified from the visual inspection

c)

Suspicion of poor workmanship or poor materials


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d)

Leakages revealed from other tests

e)

Frequent surcharging of the structure is possible

The test should be carried out only after the structures have achieved sufficient strength to withstand the test pressure. Where possible, the test shall be carried out before backfilled or concrete surrounded. For manhole less than 1.5 m in depth, the manhole shall be filled with clean water to of cover. more m in depth,level, the water head for thethe testbottom shall not be lessFor thanmanhole 1.5 m or the than mean1.5 groundwater whichever is larger. For any other ancillary structure, the water shall be filled to the top of the structure unless otherwise specified by the authorised inspection person. The procedures for testing the manhole are listed below. For other ancillary structures, the procedures can still be adopted. However, the height which the water level should be tested shall follow the instruction from the authorised inspection person.

4.12.2

Procedures a)

Fit a plug or stopper in all the openings.

b)

Secure the plug/stopper to resist the full test pressure.

c)

Provide a mean to remove the plug/stopper from the ground level safely if test water is allowed to be discharged to the downstream. (The plug/stopper may need to be remove while the structure is still full of water. Alternatively, a potable submersible pump might be sunk into the test structure to remove the water.)

96

d)

Fill the structure with clean water. Fill slowly to avoid any intense pressure impact from the water.

e)

Observe visually to identify any water leakage to the outside of the structure. Drain the water to repair the leakage if necessary.

f)

Otherwise, allow the water to stay in the test structure for 8 hours. Investigate any appreciable water loss.

g)

Drain and dispose of the test water from the test structure in an appropriate manner and to an suitable location.

Volume 3


APPENDIX A

Appendix A

APPENDIX A

Figure A.3

:

Standard Precast Concrete Manholes (Shallow, 2.5 to 5 metres, and > 5 metres depth): Add standard drawing for large diameter manhole with RC chamber. Page 107.

Figure A.4

:


Figure A.5

:

Standard Precast Remove or obstruct repositionoperations landing for clear Deep passage from Concrete manhole Manhole: top, as landing may activity (eg. jetting hose).Page 109.

Figure A.5

:


Figure A.6

:

Standard External Drop Junction: Present susceptible to blockage. Improve construction details to minimise blockage Page 110. a.

Outlet for 90 deg bend pipe, to raise to min. 300 mm above crown of sewer pipe.

b.

Size of drop pipe min. 300 mm dia.

Figure A.13 :

Typical Induct Vent Detail: Delete this figure, as not applicable. Page 117.

Figure A.14 :

Typical Details of a Wet Well Submersible Pump Station: Review, include also typical details not using the circular wet well type (which is now not common). Page 118.

Figure A.18 :

Buffer Zone for Pump Station with and without Super Structure: Buffer zone for fence to fence, add note “where located in high risk areas, brickwall fencing may be specified for safety”. Page 122.

Figure A.19 :

Buffer Zone for Pump Station with and without Super Structure: Buffer zone for fence to fence, add note “where located in high risk areas, brickwall fencing may be specified for safety”. Page 123.

Note: Other figures added are distributed as hard copies for incorporation in the documents.

OTHER COMMENTS

a)

Clause 2.5.2, 1 (Oil & Grease Trap) - Drawings sub mission by dev elopers must show O&G traps have been provided for these premises where grease and fat are likely to be discharged to sewers. Page 6.

b)

To include a section on Inverted Siphons - Standard drawings for inverted siphons to be included, but they must be designed for individually based on actual locations.

c)

Clause 2.2.4, (Structural Design Consideration for Manholes) manholes shall not be provided, for safety. Page 50.

SewerNetworksandPumpStations

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- Iron steps in

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Appendix A

Figure A3 : Typical Shallow Precast Concrete Ma nhol e (Grou nd Level to Invert of Pipe 1.2m Depth 2.5m D E IR U Q E R S A S G N I R P U E K A M .C R T S A C E R P

IX M R A T R O M T N E M E C :3 1 E M A R F .I D E L O H N A M D R A D N A T S

O T R E V O C E L O L H E N V A E L M E F C O A P F O R T U H S C D T E A H M S I O IN T F

F O S R E H Y A T I L W 2 .) B H N I A IT M L S W .K H R D E T E T 0 V I 0 O N C A (1 P C E Y R D X O I T S S P A R E C E L E D A R N O P U C

0 2 H IT W G IN R R E B M A H C

.C R T S A C E R P

A N I M U L A

H G I H F O G IN IN L L A N R E T N I . N I M

D N U O R R U S E T E R C N O C U T I S N I T S

R A T R O

I H T W L L I F

S IL A T E D O T R E V O C D N A

G N I H C N E B E T E R C N O C

) N I M . K H T 0 5 A (1 C

M T N E M E C

A IN M U L A H G I H 0 (2

) G N I R E D N E R T N E M E C

0 /2 0 2 E D A R G 0 0 .4 IN M

S U IO IT T N E M

E S A B . C N O C

E .C K H T 0 5

2 :1 1

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0 0 6

600 (MAX.)

H IG H K C I H T 0 4 G N I S U L E N N A H C M R O F

350 (MAX.)

E M A R F .I D E L O H N A M D R A D N A T S

T N E M E C 3 :1 M IX H R T I A WT L R IL O F M

S L I A T E D O T R E V O C D N A

D E IR U Q E R S A S G N I R P U E K A M .C R T S A C E R P

O T R E V O C E L O H N A M F O P O T

H T I W B A L S R E V O C C R T S A C E R P

L E V E L E C A F R U H S C D T E A H M S I O IN T F

F O S R E Y A L 2 .) H N I IT M W .K D H E T T 0 N I 0 A (1 P Y E X O ID P S R E E L D A N O U C

A 0 IN 2 M H U L IT A WH G G I N I H R F R O E B G I M N A IN H L C L .C A R N T R E S T A N C I E .N R I P M

D N U O R R U S E T E R C N O C U IT S IN T S A C

R A T R O M T N E M E C

G IN H C N IN E WW B O O L D L F N F A T N I E C A P I E M I F P R D D O N O N U T O I O D T R E C F P E L A R A H I H S D

0 /2 0 2 E D A R G 0 0 4 . IN M

) IN M . K H T 0 5 1 (

0 0 6 1

R E E T R E E M H A WI R D A R T O R N O O I M T T C N E E IR M E D C N I A E N I G M N U A L H A C

S IL A T E D O T

T N E M E C :3 IX 1 H M R T I A WT L R IL O F M

D E IR U Q E R S A S G IN R P U E K A M .C R T S A C E R P

D E R R V A D O C N D A T N S A

E S A B . C N O C

Y A /W B 0 5 -1 2 1 T

2 :1

O T R E V O C E L O H N A M F O P O T H C T A M

L E V E L E C A F R U S

D E H IS O N I T F

H T I W B A L S R E V O C C R T S A C E R P

F O S R E Y A L 2 .) H IN IT M W .K D H E T T 0 N I 0 A 1 ( P Y E X O ID P S E R E L D A N O U C

A 0 IN 2 M H U IT L A WH G IG IN H R F R O E B G M IN A N I H L C L .C A N R R T E S T A N C .I E R IN P M


A IN M U L A H IG H 0 2 (

) G IN R E D N E R T N E M E C

E 3 G N R A O H H C S 2 E IG E R R H R U A C K E C E IC H O R H WR E T R E H 0 A T T 4 T E R G R M O O A E IN M I L S D U T R O N H L E O N E N M N A N E O I M A C T H A C H G C N I E U M M IR O R U D R L N H O A F I T

D N U O R R U S E T E R C N O C ) U IN IT M S .K IN H T T S 0 A 5 C (1

N E M E C . G K IN H D T IN 0 L 5 B

) S E R T E M .5 2 < D < .2 1 E IP -B P B F N O IO L T E V C E E S L T R E V IN O T L E V E L D N U O R (G



0 /2 0 2 E D A R G 0 0 4 . IN M

G N I M O C IN

Volume 3

S N E M I D . 2

T N E M E R I U Q E R D N A N IO IT D N O

C IL O S E N I M R E T E D O T D E IR . U G Q N I E P R IL S I R I O S F . 3

B ) S E R T E M .5 2 < D < .2

G IN D IN L B

E S A B . C N O C

. D E T A T S E S I W R E H T O S S E L N U S R E T E IM L I M N I E R A S N IO

W E S

Y A /W B 0 5 -1 2 1 T

G IN H C N E B E T E R C N O C

:S E T O N

. S R E W E S O R T P E T U E S M R A E ID WR E E S G R R O A F L G R N O O F L G 0 N 0 O 6 L E 0 B 0 L 9 L A D N H A S R E E P I T P E R M E IA K C D O 0 0 R 3 . 1

S R E

2 :1 1

0 0 6

350 (MAX.)

Page 100

D N U O R G (

S U IO IT T


) 0 0 6 < P O R D E E R F ( -A A N O I T C E S

E R E H T R O S E L R E O W H E N A S G M N H I G M U O O C R IN H T 3 S R R O U 2 C E C R O A

350 (MAX.)

E M A R F .I D E L O H N A M

G IN D IN L B

) S E R T E M .5 2 < D < .2 1 E IP P F O L E V E L T R E V IN O T L E V E L

S U IO IT T N E M E C . K H T 0 5

-A A N IO T C E S

1 E IP P F O L E V E L T

R E V N I O T L E V E L D N U O R G (

A

A Ø

W IE V N A L P

6 0 0

B


Appendix A

Figure A4 : Typical Shallow Precast Concrete Ma nhol e with Backd ro (Groun d Level to Invert of Pipe 1.2m Depth 2.5m)

D E IR U Q E R S A S G N I R P U K E A M


T N E M E C :3 X I 1 M H T I R A WT L R L I O F M

S L I A T E D

.C R T S A C E R P

O T R E V O C E L O H N A M F O P O T H C T A M O T

F O S R E H Y A .) T I L N I W 2 B H .M A T K L IW H S T R D m E µ E T V N 0 0 O I C A (1 C P Y R E X O T ID P S S E A R C E L E D A R N O P U C

L E V E L C E A F R U S D E H IS IN F

F O E C A F R U S N E H G U O R D N A R A E L C

A 0 N I 2 M H U L IT A WH N G IH I G R F

R O E B G M IN A IN H L C L .C A N R R T E S T A N C .I E I R N P M

E T E R C N O C T A E N Y L P P A D N A

R O F T R O P P U S

D N E B . G E D

G N I R U O P

0 9 E L O H N A M P O R D

O T N R IO IO T E R C L E O P S H E P N T S O A A R MP D

H IG H K IC H T 0 4 G N I S U

L E N N A H C M R O F

R E E T R E E H M W IA R D A R T O R N O O I MT T C N E E IR MD E C IN A E IN N MG U A L H A C

R O E L O H N A M H G U O R H T S R U C C O

S R E W E S

' A ' L I A T E D

G N I M O C IN 3 R O 2 E R A E R E H T

D A E R S GA 0 B 0 . 4 . C N IN O MC


O T R E V O C D N A

Y A W / B

2 1 : 1

0 5 -1 2 1 T

' 'A IL A T E D E E S

0 0 6

2 :1 1

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U IT S N I T S A C



D E R I U Q E R S A S G N I R P U E K A M .C R T N T E S A M C E E C R 3 : IX P 1 H M R T I A T W L R IL O F M

F O

O T R E V O C E L O L H E N V A E L ME F C O A P F R O U T H S D C T E A H M IS O IN T F

S R E Y H A IT L W 2 .) H N B T I A I M L W . S K H R D T E E V T 0 O IN 0 C A (1 Y C P R E X O I P T D S S A R E C E L E D A R N O P U C

A I 0 N 2 M H U T I L A WH G G I N I H R F R O E B G I MN A N I H L C L .C A N R R T E S T A IN C. E R IN P M



) IN M . K H T 0 5 (1 D N U O R R U S

D N U O R R U S E T E R C N O C U T I S N I T S A C

) N I M . K H T 0 5 1 (

) G N A IR N I E MD U N L E A R H T G I N E H M 0 E (2 C

) G G IN I H A N R C N N I E E MD B U N L E E A R T E H T R N C IG E N H M O 0 E C 2 ( C

0 2 / 0 2 E D A R E S G A 0 B 0 . 4 . C N N I O MC

2 1

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H G I H K IC H T 0 4 G IN S U L E N N A H C M R O F

Volume3

E G N A H C S E R R U E C H C WO R R E A T T E R M OA I MD T N R E O MN E IO C T A C IN E M IR U L D A IN

3 R O 2 E R A E R E H T R O E L O H N A M H G U O R H T

S U O I IT T N E M E C . K H T 0 5

G IN D IN L B

) S E R T E M .5 2 < D < .2 1 E P I P F O L E V E L T R E V N I O T L E V E L D N U O R (G

S T L O B G A R D E IS N A V L A G 2 1 Ø .s o n 3

. S R E W E S

S R E H S A W D N A S T U N L A T E M N U G H IT W 375 125

5 2 1 5 7 3

E T A L P .S M . K H T 2 1

: S E T O N

OR T E P T U E S M R IA E D WR E E S G R R O F A L GR N O OF L G 0 N 0 6 O E L B 0 0 L 9 L D A H N S A E R P I E T P E R M E IA K D C 0 O0 R 3 . 1

. D E T A T S E S I W R E H T O S S E L N U S R E T E M I IL M IN E R A S N IO S N E

IM D . 2

T N E M E IR U Q E R D N A

N IO IT D N O C IL O S E N I M R E T E D O T D E IR . U G QN I E L I R P S I R I O S F . 3

S IL A T E D E T A L P R E V O C

B

) 0 0 6 > P O R D K C A (B -A A N IO T C E S

Y A W / B 0 5 -1 2 1 T

0 0 6


) 0 0 6 > P O R D K C A (B -B B N O I T C E S

N E M E C . G K IN H D T N I 0 L 5 B

350 (MAX.)

E T E R C N O C

1/2Ø+100 H T I W S S T R L E O H B S G A A R W D D N E A S I T N U A V N L L A A G T . E IA M D N 2 U 1 G

0 0 /2 2 E

) S E R T E M .5 2 < D < .2 1 E P I P F O L E V E L T R E V IN O T L E V E L D N U O R (G

A

Ø

A 60 0

B

S R E W E S G IN M O C IN

Page101

W E I V N A L P

Appendix A

Figure A6 : Typical Medium Precast Concrete M (Grou nd Level to Invert of Pipe 2.5m



D E IR U Q E R S A S G IN R P U T E K N A E M M E .C C R :3 X T 1 IM S H R A T C I A WT E R L R P L I O F M

Y L L A N R E T IN D E T N I A P P O T R E P A T .C R T S A C E R P

O T R E V O C E L O L H E N V E A L ME F C O A P F O R T U H S C D T E A H MS I O IN T F

. N I M 0 2 H A I IT N WM U G L IN A R H R G I E H B M F A O H G C IN .C IN R L T L S A N A R C E E T R P N I

Y X O P E R A T L A O C F O S R E Y A L 2 H IT W

T F R OCO P E NP CO A CU F T S RA G U IN S E NR NY U E L O HP G O UP A P O T RD NR D A IO NE R A L P RO E A HT NS E A L A C MP

D N E B . G E D 0 9 E L O H N A M P O R D

N IT O C E S P O R D R O F

' 'A IL A T E D 0 /2 0 2 E D A E R S G A 0 B 0 . 4 . C N N I O MC


' A ' L I A T E D E E S

0 0 6

Y A /W B 0 5 -1 2 1 T

2 1 : I

2 1

G N I D IN L B S U IO IT T

350 (MAX.)




D E IR U Q E R S A S G N I R P T U N E E K M A E M C .C :3 X 1 IM R H R T IT A S A WT C L R E L I O R F M P


Y L L A N R E T N I D E T N I A P P O T L E V E L E C A F R U S D E H S I IN F

R E P A T .C R T S A C E R P



) N I M . K H T 0 5 (1



H IG H K IC H T 0 4 G IN S U L E N N A H C M R O F

. N I M 0 2 H A I IT N WM G U L N I A R H R G I E H B F MO A H G C IN N I .C L R L T S A A N C R E E R T P IN



E G N A H C S E R R U E C H C WO R R E A T T E R M O A MI T D N R E O MN E O C IT A C IN E MR I U L D A N I

0 2 / 0 2 E D A R G 0 0 4 . N I M

) N I M . K H T 0 5 1 (

3 R O 2 E R A

E R E H T R O E L O H N A M H G U O R H T




Volume3

E G N A H C

) S E R T E M 5 < D < .5 2 E IP P F O L E V E L T R E V N I O T L E V E L D N U

G A R D E IS N A V L A G 2 1 Ø .s o n 3

1/2Ø+100

. . S R D E E T W A E T S S R E E S T I E W M R E A I H D T W O E R S S E G S R R E L O A F L N G R U N O S O F R L E 0 G N T E 0 O 6 L M I E 0 L B 0 I L 9 M L N I A D N E H A S R E R A E P I T S P E N R M IO E A S K ID N C 0 E M O 0 I R . 3 .D 1 2 O T P U S R E

S T U N L A T E M N U S G R H E T I H S WA S T W L D O N B A 375 125

5 2 1 5 7 3

O R (G

E T A L P .S M . K H T 2 1

: S E T O N

T N E M E IR U Q E R D N A N IO IT D N O C L I O S E IN M R E T E D O T D E R I .G U N QI E IL R P IS R I O S F . 3


B E S A B . C N O C

Y A /W B 0 5 -1 2 1 T

H IG H K IC H T 0 4 G N I S U L E N N A H C

H T I W S S T L R E O H B S G A A R W D D N E A IS T N U A V N L L A A G T . E A I M D N 2 U 1 G

S R E W E S G IN M O C N I

2 1


) 0 0 6 > P O R D K C A B ( -B B N O I T C E S

N E M E C . K H T 0 5

0 0 6

350 (MAX.)

anhole wit h backdr op Depth 5m)

S E R R U E C H C WO R R A E T T R A O M M IA T D N R E O M N E O C IT A C IN E M M IR R U D O L F A N I

3 R O 2 E R A E R E H T

R O E L S O R H E N A W E M S

S U O I IT T N E M E C G . IN K H D T IN 0 L 5 B

) 0 0 6 > P O R D K C A B ( -A A N O I T C E S

) S E R T E M 5 < D < .5 2 E IP P F O L E V E L T R E V IN O T L E V E L D N U O R G (

A

A

00 Ø6

B

H G G IN U O M R O H C T N I

Page103

W E I V N A L P

Appendix A

Figure A8 : Typical Dee p Precast Concrete Ma nhol e with Backdro p (Grou nd Level to Invert of Pipe 5m Depth 9m)


D E IR U Q E R S A S G IN R P U T E N K E A M M E .C C R 3 X : I T 1 S H M A R C T I A E WT R L R P IL O F M



Y L L A N R E T IN Y D X E O T P N I E A R A P T P OL T A O R C E P F A O T S .C R E R Y A T L S A 2 C H E T R I P W

L E V E L E C A F R U S D E H S I N I F

T F R OCO E NP C OP A CU F T S R UA G IN S E N N R E Y O U HL P N GP P O I U A OT ODT C RN RE S D A IO NE RP A L P O R OE D RH T A E NS R L A A O C MP F

.N I M 0 2

H A T I I N WM U G L IN A R H R IG E H B F M A O H G C IN IN .C L R T L S A A N R C E E T R P IN

' 'A IL A T E D

D N E B . G E D 0 9 E L O H N A

0 2 / 0 2 E D A R E S G A 0 B 0 . 4 . C N IN O MC

M P O R D


' 'A IL A T E D E E S

0 0 6

Y A W / B 0 5 -1 2 1 T

2 1 : I

350 (MAX.)


D N U O R R U S E T E R C N

O C U IT S IN T S A C


S IL A T E D O T R E V O C D N A

D E R I U O Q T E R R E V S O A C S E G L IN O R H P N T U A N E M E K F M A O E MP C O :3 IX .C T 1 M R H H R T C T I A S A T A WT C M L R E L I O R O F M P T

Y L L A N R E T N I D E T N I A P P O T L E V E L E C A F R U S D E H S I IN F

R E P A T .C R T S A C E R P

) N I M . K H T 0 5 1 (

. IN M 0 2


H A I IT N WM U G L N I A R H R IG E H B F MO A H G C N I I .C N R L T L A S N A R C E E T R N P I

R A T R O M T N E

M E C


A IN M U L A H G I H 0 2 (

) G N I R E D N E R


T N E M E C

E G N A H C S E R R U E C H C WO R R E A T T E R M O A MI T D N R E O MN E O I C T A C IN E M IR U L D A IN


E R E H T

R O E L S O R H E N A W E MS H G G N U IM O O R H C T IN

0 2 / 0 2 E D A E R S G A 0 B 0 . 4 C . N IN O MC

) N I M . K H T 0 5 1 (

Y A /W B 0 5 -1 2 1 T


A IN M U L A H IG H 0 (2

)G IN R E D N E R T N E M E C


Volume3

E G N A H C S E R R U E C H C WO R R E A T T A R M O A I MD T N R E O MN E O I C T A C IN E M IR U D L N A I

) S E R T E M 9 < D < 5 E IP P F O L E V E L T R E V N I O T L E V E L D N U O R (G

G A R D E IS N A V L A G 2 1 Ø . s o n 3

1/2Ø+100 S R E H S A W D N A T U N L A T E M N U G

S T U N L A T E

M N U S G R H E T H I S WA S W T L D O N B A 375 125

5 2 1 5 7 3

E T A L P .S M . K H T 2 1

: S E T O N

. S R E W E S OR T E P T U E S M R A E ID W E R S E G R R O F A L GR N O OF L G 0 N 0 6 O E L 0 B 0 L 9 L A D H N S A E R E P I T P E R M E A K ID C 0 O0 R . 3 1

. D E T A T S E IS W R E H T O S S E L N U S R E T E M I L I M IN E R A

3 R O 2 E R A E R E H T R O E L O H N A M H G U

S U IO IT T N E M E C G . IN K H D T IN 0 L 5 B

) 0 0 6 > P O R D K C A B ( A A N O I T C E S

) S E R T E M 9 < D < 5 E IP P F O L E V E L T R E V N I O T L E V E L D N U O R G (

A


A

00 Ø6

B

S R E W E S G IN M O O R C H N T I

Page105

T N E M E IR U Q E R D N A N O I IT D N O C L I O S E IN M R E T E D

O T D E S IR . N UG IO Q N I S E L I N RP E S I R M I I O D S F . 2 .3

B

0 0 6

350 (MAX.)

3 R O 2 E R A

G IN D IN L B S U O I T I T N E M E C . K H T 0 5

) 0 0 6 > P O R D K C A B ( -B B N IO T C E S

H IT W S T L O B G A R D E S I N A V L A G . IA D 2 1

W IE V N A L P

Appendix A

Figure A10 : Typical Induc t Vent De tail

Induct Vent

Centreline of manhole

150 Min.

750 Min.

Inside face of Manhole

150 Min.

Column Support

Notes : 1. All dimmensions are in millimetres. 2. Diameter of induct vent shall be approximately 1/2 of the forcemain but shall not exceed 300mm. SewerNetworksandPumpStations

Volume3

Page107

Appendix A

Figure A13 : Typical Deta ils of Invert ed Siphons o r Depressed Se wer

C

N IO T A V E L E T R E

Ø 0 5

Ø 0 5 7

7

D

D

: S E T O N

S R E W E S R E T E M IA D

S U J O T N O S R E P D E I F I L A U Q . 2

D E T A T S E IS W R E H T O

S S E L N U S R E T E M I L I M IN E R A

G S N IN O L I IS P N T E U M O I H D IT L L W .A 3

V O F IN 400

R E B M A H C T E L T U O F O N A L P

T E L IN 0 5 7

R S E R G E R WA E L S R R O O F F G G N N O O L L 0 0 0 0 9 6 D E N B A L R L E A T H E S M E IA IP D P 0 0 R 3 E K O C T O P R U . 1

N IO T A L L A T S IN E L O H N A M Y IF T

250

D D N IO T C E S

C C N IO T C E S

) L A C I P Y (T E ID U G E T A G E ID L S

R E B

M A H C T E L T U O Ø 0 0 5

Ø 0 5 3

232 375

Ø 0 0 5

Ø 0 5 3

Ø 0 0 4

C

A

Ø 0 0 5

Ø 0 5 3

Ø 0 0 4 Ø 0 0 5

R E B M A H C T E L N I

B

B

N IO T A V T E E L L E IN T 0 R 5 E 7 V F N I O

Ø 0 5 3

232 125

R E B M A H C T E L N I F O N A L P

0 0 0 2

) L A IC P Y (T E D I U G E T A G E ID L S

A A N IO T C E S

B B N IO T C E S

375

Ø 0 5 7

Ø 0 5 7

A

Page 110

Volume 3


Appendix A

Figure A14 : Typical Details of Receivin g Manhole, Force Ma in and Washou t Valve E IP P R E W E S Ø 0 0 3

R E V O C N O IR E L I T C U D Y T U D Y V A E H

E S E S R S E S U I R O WU C R O E E H C L T G O4 IN S O S (S S E E L L H L T N A WU Y K D B D IC E S R U IE F B I ) E C . Y B E X A L OP A C T S M

N O D E D D E B E M A R F ( E M A R F

) R A T R O M T N E D N M E A C

E IP P T E K C O R

F O R E Y A L 2

E R L E G B N A M ° H A 5 4 C

O T T C U D T N E V :3 1 R A T R O M T N E M E C H T I W L L I F

C R T S A C E R P Y T U D Y V A E H

7 A C R B

S R E Y N A O L 2 Y X H O IT P WE B R E A A L T ID S L S A R R O E E V C D O F N C OU

R E B M A H C T N E V

G IN IN L A IN M U L A . K H T 2 1

G IN R E D N E R . K H T 0 2

H T U O M L L E B

A IN M U L A H IG H :2 1 IN

E

D N A S & T N E M E C

E L O H N A M G N I IV E C E R F O L I A T E D

2 :1 1 E P O L S H IT W

R E B

C R U IT S IN T S A C . K H T 5 2 2

M A H C U T I S N I T S A C

2 H IT W 0 2

E 8 D A A C R R G B E F L O O H R E N Y A A ML

0 2 E

E L A C S O T T O N

N

D N U O R R U S

E T E R C N O C . K H T

O R G

0 5 1

E V L A V

. .S M E L B A K A E R B N U . K H T 2 1 x 0 0 0 1 x 0 0 0 1

G N I L P U O C E L IB X E L F E V O B A IN A M E C R

D N E B ° 5 4

O (F IN A M E C R O F

E V L

N A L P

G

S T IN O J E G N A L F

' À IL A T E D

A V IR A

) Y E R G D E T N I A P E B O T D N U O R G

O C

E V L A V T U O H S A W 0 5 1 Ø

L L A F T U O E L B A IT U S R O IN A R D O T Y L L U F E R A C . K H T 0 0 1

E D A R G E T E R C N O C . K E H S T A 0 B 0 0 3 2

0 5 Ø . S S O E L N O 3 H

E D A R G E T E R C N O C . K H T 0 0 3

. X A

M 0 2 D E E T T A C G A E P R MG O G C A

E V L A V T U O H S A W F O N IO T A L L A T S N I F O IL A T E D

T R O P P U S 0 2

E L A C S O T T O N

K C O L B R T O I H U C S N O A T

D N E B ° 5 4

E V L A V E C IU L S

E E T D E V O R P P A

K C O L B R O IT H U C S N O A T


S E L N U S E R T E IM L L I M N I E R . A D S E N T A IO T S S N E E S I IM W D L R L E A H . T 3 O

S R E W E S F O E IN L . R E E T T IS N E N C O D D N E A N I S M R R E E V T O E C D

T S K U C R O H L T B

G IN L P U O C E L IB X E L F

) Y E R G D E T IN A P E B O T D N U O R

G IN R E T E R C N

H IT D WN D A D E Y C E H N A K T I A R Y WL B H T L D I D A E WE N N E T R E T IN E F E A T F I L P N T P D I S MN T T O A IN N C R A A A P Y L E E S L P M A G U L R OA E R F G N U L IN I N R Q E K ME E E C U T H T O IT X C S L B E

A

E V O B A IN A M E C R O (F IN A M E C R O F

T S A C E R P D R A D N A T S 0 0 2 1 Ø

R U O C S 0 5 1 Ø

N A L P

K C O L B R T O I H U C S N O A T

M F O N IO T A T N IE R O . 2

B L L A H S

O C N A E L . 7 K E H D T A 0 R 5 G

L E V E L D N U

R O T P A D A E G N A L F

S E C C A N IO IT S O P E L O H N A

. C N

.I . D Ø 0 0 2

T T E O K T G I C IN P OO S S J

A

: S E T O

D A R G E S A B

S T IN . O R J A S T T R N O E M N T O N P E MM O E C C E :3 L O 1 H H N IT A W MD T E S L A L I C F E E R P B L L L L A A . H 1 S

N IO T A V E L E S T N I O J E G N A L F

T R E V L U C R E V O G IN S E S LA O SC R TO CT O IN N A M E C R O F L A C I P Y T

IT U S

E V L A V IR A 0 5 Ø

E V L A V E IC U L S 0 5 Ø

O T E C E I P N IO S N E T X .E .I D

0 5 Ø

D E G .I N . A D L OF T N D O E E D T L A E L WP

E E T E H T

F O D N E

K C O L B R I O T H U C S N O A T

Volume3

Page111

N IO T A L L A T S IN D ) E N ' V U A L ` A O L I V R G A T IR E E A V D E O G B A A ( W E S L A IC P Y T

E L A C S O T T O N

Appendix A

Figure A15 : Precast Concrete Chamber (T ype A ) and Details of Air Valve and Scour Valve Chamber

0 0 3 0 5 1

5 2 2 5 7

0 0 9

150

150

5 7 5 2 2

0 5 1 75MIN.

225

50

50

900

380

150

225

50

50 150

380

150

0 5 1 0 5 0 5

0 3 4 0 3 4

0 5 1

0 5 0 5

900(NTS)

0 3 6

0 5 2

430

580

75

Page 112

Volume 3


Appendix A

Figure A16 : Standa rd Pipe Beddi ngs LOADFACTOR2.8

LOADFACTOR1.9 100 MIN.

150

GRADE20/20 CONCRETEBACKFI LL

0.50O.D. 0.25O.D. WITH100MIN. 150

300MIN

SELECTED COMPACTED BACKFILL

SEWERPIPE

SEWERPIPE

20AGGREGATE

20AGGREGATE

0 0 3 + D . O

0.50D 0.25O.D. W ITH100MIN.

SEWERPIPE

0.25O.D. WITH100MIN. O.D+300

0.D+300

O.D+300

CRUSHED RUN BEDDING FACTOR 1.9

CONCRETE ARCH BEDDING FACTOR 2.8

PIPEEMBEDDE DIN CAREFUL L YCOMPACTED20DIA.AGGRE GATE EXTEND INGHALFWAYUPTOSIDEOFTHEPIPE. THEREMA INDER SIDEFILLANDTOPCOMPACTEDCAREFUL LYWITHBACKFILL.

PIPEEMBEDDEDINCAREFULLYCOMPACTE D20 DIA.AGGRE GATE EXTENDIN GHALFWAYUPTOSIDESOFTHEPIPE. THEREMAINDE R SIDETOFILLANDTOPWITHMONOLITHICPLAINCONCRETE

GRADE20/20CONCRETE SURROU ND150MIN

CONCRETE SURROUND BEDDING FACTOR 3.0 (FORSEWERSWITHLESSTHAN 1MCOVER, FORCEMAINSANDINVERTEDSYPHON .)

THESELECTEDCOMPACTBACKFILLFORVITRIFIEDCLAYPIPESHALLBE COMPAC TEDDRYSOIL(FREEFROMVEGETABLEORGA NICMATTERS& EXCAVATION/COMPACTED DRYREDEARTH/SAND/CHIPPING/STONES NOT GREATE RTHAN25.

DETECTABLE MARKE RTAPE

GROUNDLEVEL

BACKFILL&COMPACTWITH SUITABLESOILTOREQUIR EDLEVEL LOADFACTOR1.9

FINALBACKFILL (SELECTE DBACKFILL)

BACKFILLWITHWELLCOMPACTEDSOIL (HANDHELDCOMPACTO R)

VARIES

300MIN

COMPACTEDSELECTED BACKFILLMATERIA L

BACKFILLWITHSAND (HANDHELDCOMPACTO R)

SEWERPIPE

300mmMIN.

0.25O.D.

GRADE20/20CONCRETE

INITIAL BACKFILL

0.25O.D. W ITH100MIN.

2

CONCRE T EGRADE25N/mm ONELAYEROFA8(BRC) 150THICKSAND

SPRINGLINE

PIPEEMBEDMENT (CRUSHERRUN)

0.D+300

SEWERPIPE

32mmØ

HAUNCHING

CONCRETE CRADLE BEDDING

SEWERPIPE 150to300mm(20mmØ)

CRUSHER RUN BEDDING FOR FLEXIBLE PIPES

"X' NO. OF70 ØBAKAUPILE(REFERTABLEÀ') 70Ø BAKAUPILEAT300C/CALONGPIPEBAKAU PILESSHALLBEDRIVENTOSETOR10mDEPTH (2 x5m LONG) WH ICHEVE RACHIEVEDFIRST

SEWER PIPE LAYING ON UNSUITABLE SOIL

NOTES: 1. THEBACKFILL MATERIALSHALLBE PLACEDOVERTHEFULL WIDTHOFTHETRENCHANDWELLCOMPACT EDIN LAYER S NOTEXCEEDING300. 2. INCREASEDINBAKAUPILESLENGTHANDNUMBER . 3. SI ISREQUIREDTODETERMIN ESOILCONDITIO NANDREQUIREMEN T FORPILING.

PIPE SIZE

MAXIMUM TRENCH WIDTH

TABLE 2

TABLE 1 MAXIMUM TRENCH WIDTH TABLE À'

NOTE: FORFILLINGOFTRENCH ESALONG/AC ROSS CARRIAGEWAY, BACKFILLMATERIALSHALL USESANDFROMANAPPROVEDSOURC E.


Volume3

Page113

Appendix A

Figure A. 17 Vacuum sewage col lectio n syst em

Figure A. 18 House connecti on

Page 114

Volume 3


Appendix A

Figure A. 1 9 (a) Example of vacuum statio n wit h hous ed collecti on vessel


Volume3

Page115

Appendix A

Figure A. 1 9 (b) Example of vacuum s tation w ith h oused col lectio n vessel

Page 116

Volume 3


Appendix A

Figure A. 2 0 (a) Collectio n chambers wi th in terface valves ve nted thr ough breather pipes

Figure A. 20 (b) Coll ection c hamber wit h int erface va lve activated by fl oat


Volume3

Page117

Appendix A

Figure A. 20 (c) Mult i-valve coll ection chamber

Page 118

Volume 3


Appendix A

Figure A. 21 Vacuum sewer prof iles (not t o scale)

Figure A. 2 2 Example of vacuum sewer profiles for transport (not t o scale)


Volume3

uphill and downhill

Page119

Appendix A

Figure A. 23 Y-branch for vacuum s ewer

Figure A. 2 4 Method of j oining crossover pip es and branch sewers to vacuum mains

Page 120

Volume 3


Appendix A

Figure A. 25 Typical details of dry-well pump station OVERFLOW PIPE DISCHARGE TO MONSOON DRAIN

OVERFLOW CHAMBER

DRAIN

RAMP DOWN

CONC. APRON LAID TO FALL

3 LAYER CONC. VENTILATION BLOCK AT TOP AND BOTTOM LEVEL

LIQUID RETURN FROM OTHER UNIT PROCESSES WP

FORCEMAIN MECHANICAL COARSE SCREEN

A A GATE VALVE.

13 14 15 16 17 18 19 20 21 22 23

INCOMING SEWER G.I CHAIN GUARD PENSTOCK GRATING COVER

AIR EXTRACTOR FAN

. D R A U G IN A DN H C 13 12 11 10 9 8 7 6 5 4 3 2 1 .I G 14 15 16 17 18 19 20 21

R.C STAIRCASE TO ENGR'S DETAIL

3 LAYER CONC. VENTILATION BLOCK AT TOP AND BOTTOM LEVEL

CHECK VALVE.

CONC. THRUST BLOCK.

12 11 10 9 8 7 6 5 4 3 2 1

CONC. THRUST BLOCK.

EXTRACTOR FAN R.C STAIRCASE TO ENGR'S DETAIL.

CONCRETE VENTILATION BLOCK AT TOP AND BOTTOM LEVEL

DN

CHAIN GUARD.

ADJUSTABLE GLASS LOUVRES WINDOW

SPOT LIGHT CHEQUER PLATE DOOR

BRICKWALL C/W CEMENT PLASTER ON BOTH SIDES DRY PIT PUMPS

PLAN VIEW

COPPER TYPE LIGHTNING ARRESTOR

LIFTING I-BEAM C/W CARRIER

R.C GUTTER TO ENGR'S DETAIL

RAIN WATER DOWN PIPE TO NEAREST SUMP

MECHANICAL COARSE SCREEN

DOOR

SCREENINGS COLLECTION BIN

BRICKWALL C/W CEMENT PLASTER ON BOTH SIDES

PENSTOCK

WINDOW HANDRAIL

CHEQUER PLATE

3 LAYER CONC. VENTILATION BLOCK

HANDRAIL R.C STAIRCASE TO ENGR'S DETAIL

WET WELL

DRY WELL

PERFORATED SLAB CAT LADDER OPENINGS

CHECK VALVE

ALARM 2nd. STANDBY PUMP START 1st. STANDBY PUMP START 2nd. DUTY PUMP START

GATE VALVE

1st.. DUTY PUMP START

INCOMING SEWER (FLOAT SWITCH)

ALL PUMPSTOP STOP LOG SUMP BWL

N.B. : The discharge level for dewatering pump shall be higher than the invert level of overflow pipe to prevent sewage from back flowing into the dry well during flooding

DEWATERING PUMP

DRY PIT PUMPS

SECTION VIEW


Volume3

Page121

Appendix A

Figure A. 2 6 Typic al deta il of w et-well pump st ation

MECH. COARSE SCREEN INCOMING SEWER STEPS GRATING COVER

OVERFLOW PIPE DISCHARGE TO DRAIN

V.C.P STAND PIPE CONC. APRON

COLLECTION BIN CLEAR SPACING S.STEEL MANUAL FINE SCREEN

OVERFLOW CHAMBER

INFLUENT PUMP

A GRATING COVER

PRIMARY SCREEN 17 18 19 20 21 22 23

A

PUMP SUMP S.STEEL HANDRAIL

STEPS

EXPLOSION PROOF SPOT LIGHT CHECK VALVE FLEXIBLE COUPLING GATE VALVE

PENSTOCK

16 15 14 13 12 11 10 9 8 7 6 5 4 3 2

1 DELIVERY PIPE

R.C STAIRCASE TO ENGR'S DETAIL

PLAN VIEW LIFTING I-BEAM C/W CARRIER MECH. COARSE SCREEN HANDRAIL CHAIN GUARD CLEARSPACING MANUAL FINE SCREEN

CHECK VALVE FLEXIBLE COUPLING GATE VALVE DELIVERY PIPE

PENSTOCK

OVERFLOW PIPE DISCHARGE TO DRAIN

NON-EXPLOSION SPOT LIGHT

DELIVERY PIPE GUIDERAIL

OVERFLOW CHAMBER

S.S PERFORATED TROUGH

PUMP SUMP

LIFTING CHAIN

PRIMARY SCREEN CHAMBER CONC. SLAB R.C WALL TO ENGR'S DETAIL

IL

1: 2

IL

FRP STOP LOG C/W HAND WHEEL IL

OPENING ALARM START

MANUAL COARSE SCREEN STOP

SECTION A-A

Page 122

Volume 3


Appendix A

Figure A. 2 7 Buffer Zone for Pump Station wit

h Super S tru ctu re

Typical Section

1. 20m buffer zone shall be provided from the external edge of the P.S super-structure fence/boundary to the nearest habitable building fence/boundary as required by building by-laws. The buffer zone shall be sufficient to allow for pump station access and working area . 2. Non-Habitable buildings may be located within buffer zone. 3. Where the pump station is located in sensitive areas, additional buffer zone may be specified for the purpose of beutification.


Volume3

Page123

Appendix A

Figure A. 28 Buffer Zone for Pump without Super Structure

Vent Vent

H Properties Fence

P.S Fence

P.S Fence

Properties Fence

G

20m i Buffer

5m

5m Access and Beutifician

Access and Beutificatio

20m Buffer

Sectional Plan

Note 1.

20m Buff er zone shall be provided f rom the perimeter (f ence/boundary ) of the pump station to t he nearest habitable building fenc e/boundary as required by building by-laws. The buffer zone shall be sufficient to allow f or pump station access and working area.

2. Non-habitable buildings may be located within the buff er zone but shall not obstruct operation, maintenance and access. 3. H is the height of t he v ent pipe which shall be at least higher than roof eaves lev el for buildings up to 2 storey s high. The vent cowl shall be at least 20m away f orm the nearest building window. 4. Where the pump station is located in sensit iv e areas, additional buff er zone may be specif ied f or the purpose beutification.

Page 124

Volume 3


Appendix A

Figure A. 2 9 Buffer Zone for Pump witho

Symbols

ut Super Structure

PIPE

BUILDING (WOODEN OR

DN 375 R.C.P

DN 375 R.C.P

1:80 BUILDING

1:72

PROPOSED MANHOLE AND SEWER IN PLAN

DIRECTION OF SEW ER

GATE POND PON

PROPOSED MANHOLE AND SEWER IN PROFILE

FIRE

H

PAVED RAIL CULVER

EXISTING MANHOLE AND SEWER IN PLAN

BRIDGE PAVED CHANNEL AND FLOW EXISTING MANHOLE AND SEWER IN PROFILE

UNPAVED SIDE CHAINLINK UTILITY

GAS

G

TELEPHONE ELECTRIC

W

E

STREET LIGHTSIDE POLE SIDE

T

WATER MAIN (GENERALLY 1m DEEP) ELECTRICAL TRANSMISSION LINE OR CONDUIT (GENERALL Y 1m DEEP) TELEPHONE CONDUIT (GENERALLY 1.5m DEEP)

PROPERTY, LOT OR RESERVE PROVISION FOR BACKDRO P FOR SEWER CONNECTION SEPTIC

ST

PROVISION FOR T-JOINT FOR SEWER CONNECTION

BOREHOL

Abbrev iat io ns A.C.P. C.I. CH. CL. CONC. CRS D.I. DIA.(ø) D.M.H. DN. DRG. EXIST. GD. GR. H.A.

ASBESTOS CEMENT CAST CHAINAG CLASS CONCRET CENTRE DUCTILE DIAMETE DROP NOMINAL DRAWIN EXISTIN GROUND GRADE HIGH

HORZ I.D. INV. JLN. KG. LRG. LT MAX. M.H. MIN. MOD. NO.

HORIZONTA INSIDE INVER JALAN KAMPUN LORON LEFT MAXIMU MANHOL MINIMU MODIFIE NUMBE


N.T.S. O.D. R.C. R.C.P RET. RT S SG. SHT. SPEC STD. SCW. STL. STA. TYP. VAR. VERT. V.C.P HDPE

Volume3

NOT TO OUTSIDE REINFORCED REINFORCED CONCRETE RETICULATION RIGHT SLOPE STREAM OR SHEET SPECIFICATIO STANDAR STANDARD CUT-OUT STEEL STATIO TYPICA VARIE VERTICA VITRIFIED CLAY HIGHDENSITY

Page125

Appendix A

Page 126 (this pages is intend to blank)

Volume3


APPENDIX B

Appendix B

Table B1

Classe s of Rigid Pipe Require d fo r Various Depth

H T P E D S U IO R A V R O F 1 . B E D E L IR B U A T Q E R E P I P ID IG R F O S E S S A L C

E P I P Y A L C


Volume3

Page127

Appendix B

128 (this page intended to be blank)

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APPENDIX C

Appendix C

Ap pen di x C 1

Report fo rmat fo r CCTV In sp ect ion

Contractor :

Project-Information ProjectName:

ProjectNumber:

Client Contact Position Road Town State Telephone Fax Mobile E- Mail

:

Site Contact Position Road Town State Telephone Fax Mobile E-Mail

:

Contractor Contact Position Road Town State Telephone Fax Mobile E-Mail

:

Contact:

Date:

: : : : : : : : :

: : : : : : : : :

: : : : : : : : :


Volume3

Page129

Appendix C

Ap pen di x C 2

Report f or mat for CCTV Inspec ti on

Contractor :

Inspection Report Date:

Job nr:

Weather

Operator

SectionNumber

PLR:

Present:

Vehicle:

Camera:

Preset:

Cleaned:

Grade:

R

oad:

Division:

Start MH:

P

lace:

District:

End MH:

L

ocation:

Tape No.:

P

urpose: Use:

C

Total Length: Size/Shape: Material:

atchment:

Lining: Category:

Comment: Location details: Slope

Position

Code

Observation

Counter

Photo

Grade

MH No.

130

Volume 3


Appendix C

Ap pen di x C 3


Contractor :

Inspection Photos Town :


Road :

Date :

Volume3

Section Nmber :

PLR :

Page131

Appendix C

Ap pen di x C 4

Report f or mat for CCTV Inspec ti on

DEFECT SUMMARY OF PIPE SECTIONS INSPECTION From MH :

Item Start MH

To MH :

End MH

PipDiea. Material (mm)

Infiltration Pipe Wide Cracksor Others Length( M) Seeping Dripping Running Joints Fractures

Section Total

Comments

N.B : When more than one defect is recorded at the same chainage, the most severe defect is counted. PreparedBy:

Date Report Of :

132

Approved By : ( Qualified Person )

PreparedBy: (Name:QualifiedPerson&Company)

(Name:QualifiedPerson&Company) Date Report Of :

Date :

Volume 3


Appendix C

Ap pen di x C 5


DEFECT SUMMARY OF PIPE SECTIONS INSPECTION

FromMH:

Item No.

ToMH:

StartMH FinishMH


Position (M)

Code

Volume3

Description

Grade

Page133

Appendix C

Ap pendi x C 6

Mod ul es

Section 5 - Structural Defect Coding (Module 6A) C CL CC CM CS

CRA CK Longitudinal Circumferential Multiple Spiral

5.1 5.2 5.2 5.2 5.2

S

SURFACE DA MA G E Roughness Increased SRIM Mechanical SRIC ChemicalA ttack SRIZ NotEvident

5.30

S

SRI

5.30

SAV SAVM SAVC SAVZ

S SURFACE DA MA G E SMV Missing Wall SMWMM echanical SMWC ChemicalAttack SMWZN otEvident

5.31 5.31 5.32 5.30 5.31 5.31 5.31 5.32

RP

POINT REPAIR

5.62

RPR RPRD RPP SMWZ

Pipe Replaced Defective PatchRepair NotEvident

5.62 5.62 5.62 5.32

134

F FL FC FM FS

FRACTURE Longitudinal Circumferential Multiple Spiral

5.7 5.7 5.7 5.7 5.7

B BROKEN 5.14 H HOLE 5.16 D DEFORMED 5.18 BSV SoilVisibleBeyond 5.14 HSV SoilVisibleBeyond 5.16 DV DeformedVertically 5.18 Defect Defect (brick) BVV oldVisibleBeyond 5.14 HSV oldVisibleBeyond 5.16 DH Deformed 5.18 XB Defect Defect Horizontally (brick)

SU RFACE 5.30 S SURFACE DA MA G E DA MA G E Aggregate Visible 5.30 SAP Aggregate Mechanical 5.31P r oje ct i n g Chemical Attack 5.31 SAPMM echanical NotE vident 5.32 SAPC ChemicalA ttack SAPZN otEvident

S SU RFACE 5.30 S SURFACE DA MA G E DA MA G E SSS Surface Spall ing 5.31 SZ Oth er SSSM Mechanical 5.31 SZM Mechanical SSSC ChemicalAttack 5.31 SZC ChemicalAttack SSSZ NotEvident 5.32 SZZ NotEvident

5.30

S SU RFACE D A MA G E 5.30 SAM Aggregate Mi s s i n g 5.31 SAMMM echanical 5.31 SAMC ChemicalA ttack 5.32 SAMZN otEvident 5.30 5.31 5.31 5.31 5.32

S

SU RFACE D A MA G E

SCP Corrosion (metalpipe)

X

COLL AP SE

XP Pipe Collapse BrickCollapse

5.22 J JOINT JO JointOffset(Displaced) 5.25 5.22 JS Joint Separated (Open) 5.2 5.22 JA JointAngular 5.25

5.30

S SU RFACE 5.30 S SU RFACE 5.30 S SURFACE DAMAGE DA MA G E DA MA G E 5.30 SRV Reinforcement 5.30 SRP Reinforcement 5.30 SAP Aggregate Projectin V i si bl e P r oj e ct i ng 5.31 SRVMM echanical 5.31 SRPMM echanical 5.31 SAPMM echanical 5.31 SRVC ChemicalA ttack 5.31 SRPC ChemicalA ttack 5.31 SAPC ChemicalA ttack 5. 5.32 SRVZN otEvident 5.32 SRPZN otEvident 5.32 SAPZN otEvident 5.32 5.30

LF

LINING FAILURE 5.44 LF LINING FAILURE 5.44 WF WELD FAILURE (continue) LFD DetachedLining 5.44 LFOCO vercutService 5.44 WFL Longitudinal 5.31 LFDE DefectiveEnd 5.44 LFUC UndercutService 5.44 WFG Circumferental 5.31 LFB BlisteredLining 5.44 LFBK BuokledLining 5.44 WFM Multiple 5. LFCS ServiceCutShifted 5.44 LFW WrinkledLining 5.44 WFSS piral 5.56 LFAC Abandoned 5.44 Connection LFZ Other 5.44 WFZU nidentified

RP POINT REPAIR 5.62 (continues) RPL Localized Pipeli ner5.62 RPLD Defective 5.62 RPZ Other 5.62

Volume 3


Appendix C

136 (this page is intended blank)

Volume3


Suruhanajaya Perkhidmatan Air Negara (SPAN) Kementerian Tenaga, Air dan Komunikasi Block E4/5 Parcel E Pusat Pentadbiran Kerajaan 62668 Putrajaya Malaysia Tel: 03-8883 6000 Fax: 03-8889 3712 http://www.ktak.gov.my e-mail : [email protected]

Malaysian Sewerage Industry Guideline (Volume III) 1st Edition

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