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Water and WastewaterDesign Guideline Manual

Revision 1March 2009


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Water And Sewerage Authority (WASA)Of Trinidad and Tobago

Water and Wastewater Design Guideline Manual

GENIVAR Trinidad & Tobago Ltd.20 th Floor, Nicholas Tower

63-65 Independence Square SouthPort of Spain

Trinidad, W.I.

Revision 1 March 2009


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Water And Sewerage Authority (WASA)Water and Wastewater Design Guideline Manual Table of Contents

i March 2009R1

Table of Contents

Table of Contents

List of Abbreviations

Table of Contents .......................................................................................................... i

List of Abbreviations ....................................................................................................I

Section 1 General Information ............................................................................. 1

Other References ......................................................................................................... 1

Section 2 Design Approach & Approvals ............................................................ 1 2.1 Introduction.................... .................. .................. ................. .................. ................. .............. 1

2.1.1 Multi barrier approach......................................................................................................... 1 2.1.2 Sustainable development ..................................................................................................... 1

2.2 Design Guidelines.......... .................. .................. .................. .................. .................. ............ 1 2.3 Review process of the guidelines.................. ................... .................. .................. ................ 2 2.4 Approvals............. ................. .................. ................. .................. .................. .................. ...... 2

Section 3 Design Standards ................................................................................... 1

3.1 Design requirements ............................................................................................................ 1 3.2 Acts, Codes and Standards.................. .................. .................. .................. .................. ......... 1 3.3 Other Design & Construction Standards...................... ................... .................. .................. . 2 3.4 Industry Standards ............................................................................................................... 2

Section 4 Process and Equipment Redundancy .................................................. 1

4.1 General...... .................. .................. .................. .................. .................. .................. ............... 1 4.2 Minimum redundancy Wastewater systems ................. ................... .................. ............... 1 4.3 Minimum redundancy Drinking Water systems ................. ................... ................... ........ 1 4.4 Standby Power..................................................................................................................... 2 4.5 Standardization of Equipment............................. ................. .................. ................. ............. 2

Section 5 Design of Water Distribution System .................................................. 1

5.1 General Requirement ........................................................................................................... 1

5.2 Water Demand ..................................................................................................................... 1 5.2.1 Design Water Demand ........................................................................................................ 2 5.2.2 Average Water Demand (light industrial and commercial).. ........... ........... ........... ........... ... 3 5.2.3 Residential Per capita demand............................................................................................. 4 5.2.4 Equivalent Population ......................................................................................................... 5 5.2.5 Fire Flow Requirements ...................................................................................................... 5

5.3 Hydraulic Design ................................................................................................................. 6 5.3.1 Pipe Design Flow ................................................................................................................ 6 5.3.2 Hazen Williams roughness coefficient ................................................................................ 7 5.3.3 Standard Pipe Sizes ............................................................................................................. 7


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5.3.4 Minimum Pipe Sizes............................................................................................................ 7 5.3.5 Pressure ............................................................................................................................... 7

5.4 Trunk systems................ .................. ................. .................. ................. .................. .............. 7 5.4.1 Velocity ............................................................................................................................... 8 5.4.2 Pipe redundancy .................................................................................................................. 8 5.4.3 Pumping capacity ................................................................................................................ 8

5.5 System Layout ..................................................................................................................... 8 5.5.1 Grid System......................................................................................................................... 8 5.5.2 Location............................................................................................................................... 8 5.5.3 Separation from Stormwater and Wastewater Mains .......................................................... 9 5.5.4 Pipe Depth ........................................................................................................................... 9 5.5.5 Valves.................................................................................................................................. 9 5.5.6 Hydrants ............................................................................................................................ 10 5.5.7 Blow Off............................................................................................................................ 10

5.6 Pipe Requirements ............................................................................................................. 10 5.6.1 Pipe Material ..................................................................................................................... 10 5.6.2 Pipe specification............................................................................................................... 11 5.6.3 Structural Requirements .................................................................................................... 11 5.6.4 Tracer Wire........................................................................................................................ 12 5.6.5 Water Service Connections ............................................................................................... 12

5.7 Corrosion Prevention......................................................................................................... 13 5.7.1 Polyethylene Encasement.................................................................................................. 13 5.7.2 Polyurethane coating ......................................................................................................... 14 5.7.3 Cathodic Protection ........................................................................................................... 14

5.8 Pipe commissioning....... .................. ................. .................. ................. .................. ............ 15

Section 6 Drinking Water Reservoirs .................................................................. 1

6.1 General...... .................. .................. .................. .................. .................. .................. ............... 1 6.2 Impoundment design.................... ................. ................. ................. ................. ................. ... 1 6.3 Tank Design................... .................. ................. .................. ................. .................. .............. 1 6.4 Tank Capacity ...................................................................................................................... 2 6.5 Re-chlorination System Requirements ................................................................................ 2 6.6 Emergency Eye-wash .......................................................................................................... 2 6.7 Site Access Road and Security ............................................................................................ 2 6.8 Architectural ........................................................................................................................ 3 6.9 Structural................ .................. .................. .................. .................. .................. ................. ... 3 6.10 Mechanical......... .................. .................. .................. .................. .................. .................. ...... 4 6.11 Ventilation ........................................................................................................................... 4 6.12 Instrumentation and Control ................. .................. ................. .................. ................. ......... 4 6.13 Alarms............... .................. ................. .................. .................. .................. ................. ......... 5 6.14 Control System .................................................................................................................... 5 6.15 Equipment Redundancy.................. ................. ................. ................. .................. ................ 5

Section 7 Potable Water Pumping Stations ......................................................... 1

7.1 General...... .................. .................. .................. .................. .................. .................. ............... 1 7.2 Pump design.............. .................. .................. ................. .................. ................. ................... 1 7.3 Layout of Pumping Station .................. ................. .................. ................. .................. .......... 1 7.4 Equipment Redundancy.................. ................. ................. ................. .................. ................ 2 7.5 Pumping Station Requirements...................... .................. ................. .................. ................. 2 7.6 Control System .................................................................................................................... 2 7.7 Instrumentation.................................................................................................................... 3 7.8 Alarms............... .................. ................. .................. .................. .................. ................. ......... 3


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7.9 Ventilation ........................................................................................................................... 4 7.10 Architectural ........................................................................................................................ 4 7.11 Site Access Road and Security ............................................................................................ 4

Section 8 Well Pumping Station Design............................................................... 1

8.1 General...... .................. .................. .................. .................. .................. .................. ............... 1 8.2 Well Construction................ .................. .................. .................. .................. .................. ...... 1 8.3 Well Instrumentation & Control ................ .................. .................. .................. .................. .. 2 8.4 Alarms............... .................. ................. .................. .................. .................. ................. ......... 3 8.5 Preferred Layout .................................................................................................................. 3 8.6 SCADA System ................................................................................................................... 3 8.7 Equipment Redundancy.................. ................. ................. ................. .................. ................ 4

Section 9 Water Treatment Plants ....................................................................... 1

9.1 General...... .................. .................. .................. .................. .................. .................. ............... 1 9.2 Drinking water standards ................. .................. .................. .................. .................. ............ 1

9.2.1 Microbiological ................................................................................................................... 2 9.2.2 Naturally occurring chemicals.. ........... ........... .......... ........... ........... .......... ........... .......... ...... 2 9.2.3 Chemical contaminants ....................................................................................................... 3 9.2.4 Aesthetic guidelines............................................................................................................. 6

9.3 Performance targets and treatment objectives ................... .................. ................... ............. 6 9.3.1 General ................................................................................................................................ 6 9.3.2 Minimum treatment objectives............................................................................................ 7 9.3.3 Additional treatment objectives for Class I water supplies........... ........... ........... ........... ...... 9

9.4 Calculations of the water treatment performance ................. .................. ................... ........ 10 9.4.1 General .............................................................................................................................. 10 9.4.2 Evaluation of the water treatment efficiency... ........... .......... ........... ........... .......... ........... .. 11 9.4.3 Treatment based on physical removal of parasites and virus.............. ........... ........... ......... 11 9.4.4 Treatment based on chemical inactivation of parasites and virus....... ........... ............ ........ 14 9.4.5 Treatment based on physical inactivation of parasites and virus..... ........... ........... ........... . 14

9.5 Raw water characterisation................. .................. .................. ................... .................. ...... 16 9.5.1 Raw Water characterisation and sampling............... .......... ........... .......... ........... .......... ...... 16

9.6 Treatment plant general design..................... .................. ................. .................. ................ 18 9.6.1 Water intake ...................................................................................................................... 18 9.6.2 Monitoring......................................................................................................................... 18 9.6.3 General design elements.................................................................................................... 18

9.7 Sludge Management .......................................................................................................... 19 9.8 Disinfection design guidelines........ .................. .................. .................. .................. ........... 19

9.8.1 Chlorination System .......................................................................................................... 19 9.8.2 Ultraviolet Radiation (UV)................................................................................................ 21

Section 10 Design of Wastewater Collection System ............................................ 1

10.1 General Requirements................... .................. ................. .................. ................. ................. 1 10.2 Design Flow................. ................. .................. ................. .................. .................. ................ 1

10.2.1 Design Wastewater Flow..................................................................................................... 1 10.2.2 Average Dry Weather Flow................................................................................................. 2 10.2.3 Peak Wastewater Flow Factor............................................................................................. 3 10.2.4 Infiltration Allowance ......................................................................................................... 4

10.3 Gravity Pipe Size ................................................................................................................. 4 10.3.1 Mannings Formula ............................................................................................................. 4 10.3.2 Coefficient of Roughness .................................................................................................... 5 10.3.3 Minimum Pipe Size ............................................................................................................. 5


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10.4 Flow Velocities................ .................. .................. .................. .................. .................. .......... 5 10.5 Pipe Slopes & Manhole distances.......... .................. .................. .................. .................. ...... 5 10.6 Structural Layout ................................................................................................................. 6 10.7 System Layout ..................................................................................................................... 6

10.7.1 Location of Wastewater Main ............................................................................................. 6 10.7.2 Pipe Depth ........................................................................................................................... 6 10.7.3 Grid Design ......................................................................................................................... 6 10.8 Pipe Material........ .................. .................. .................. .................. .................. ................... ... 6 10.8.1 Concrete Pipe ...................................................................................................................... 6 10.8.2 Polyvinyl Chloride Pipe ...................................................................................................... 7 10.8.3 Polyethylene Pipe................................................................................................................ 7 10.8.4 Glass Reinforced Plastics (GRP) Pipes and Fittings.............. ........... ........... ........... ........... .. 7 10.8.5 Ductile iron.......................................................................................................................... 7

10.9 Maintenance Chamber (Manhole) ....................................................................................... 7 10.9.1 Maintenance Chamber Design............................................................................................. 7 10.9.2 Manhole Hydraulics ............................................................................................................ 8

10.10 Connection from Main to Street Line ................ .................. ................. .................. ............. 8 10.10.1 Street Line Connection........................................................................................................ 8 10.10.2 Connection Size and Grade For Multi Family Sites .......... .......... ........... ........... ........... ....... 9 10.10.3 Pipe Material ....................................................................................................................... 9 10.11 Forcemains........ ................. .................. ................. .................. ................. .................. .......... 9 10.11.1 System Design..................................................................................................................... 9 10.11.2 Pipe Size............................................................................................................................ 10 10.11.3 Pipe Depth ......................................................................................................................... 10 10.11.4 Tracer Wire........................................................................................................................ 10 10.11.5 Thrust restraint .................................................................................................................. 10

Section 11 Wastewater Treatment Plants.............................................................. 1

11.1 General...... .................. .................. .................. .................. .................. .................. ............... 1 11.2 Wastewater Effluent treatment objectives ................. ................... .................. ................... .. 2 11.3 Wastewater Loads... .................. .................. .................. .................. .................. ................... 2

11.4 Plant Layout... ................. .................. ................. .................. ................. .................. ............. 2 11.5 Plant Design Capacity........ .................. .................. .................. .................. .................. ........ 3 11.6 Equalization tank ................................................................................................................. 3 11.7 Pre treatment Inlet Works .................. .................. ................... .................. ................... ..... 3 11.8 Secondary and tertiary treatments................. .................. ................... .................. ................ 4 11.9 Disinfection System.................. .................. .................. ................. .................. .................. .. 4

11.9.1 Chlorination System ............................................................................................................ 5 11.9.2 Ultra-Violet (UV ) ............................................................................................................... 6 11.9.3 Sulphur Dioxide System...................................................................................................... 7

11.10 Sampling and monitoring..................... .................. .................. ................. .................. ......... 7 11.11 Odor Control ........................................................................................................................ 8 11.12 Structural consideration .................. .................. .................. .................. .................. ............. 8 11.13 Water reuse for irrigation............. .................. .................. .................. .................. ................ 8 11.14 Control System .................................................................................................................... 9 11.15 SCADA System ................................................................................................................... 9 11.16 Equipment Redundancy.................. ................. ................. ................. .................. ................ 9 11.17 Stormwater management ..................................................................................................... 9

11.17.1 Combined Sewer System vs. Separate Sanitary Sewer ....................................................... 9 11.17.2 Runoff impact.................................................................................................................... 10 11.17.3 Requirements..................................................................................................................... 10


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Section 12 Wastewater Pumping Stations ............................................................. 1

12.1 General...... .................. .................. .................. .................. .................. .................. ............... 1 12.2 Wastewater Pumping Station General Design.................. ................... .................. .............. 1 12.3 Wastewater Pumping Station Layout...................... .................. .................. .................. ....... 1 12.4 Configuration of Pumping System................... .................. .................. .................. .............. 2

12.5 Design Wastewater Pumping Station Sizing .................. ................... .................. ................ 1 12.6 Wastewater Pumping Station (Inflow less than 20 l/s) .................. .................. .................. .. 1 12.7 Wastewater Pumping Station (20 l/s 200 l/s).............. .................. .................. ................ 1 12.9 Pump Design........ .................. ................. .................. ................. .................. ................. ....... 2 12.10 Piping & Valve Design................ .................. .................. .................. .................. ................ 2 12.11 Corrosion resistance............ .................. .................. .................. .................. ................. ........ 3 12.12 Pump Controls ..................................................................................................................... 4 12.13 Odour Control............... .................. ................. .................. ................. .................. ............... 4 12.14 Ventilation ........................................................................................................................... 4 12.15 Equipment and Material Specifications................ .................. .................. .................. ......... 5 12.16 Site Access Road and Security ............................................................................................ 5

12.17 Instrumentation & Control Alarms ................ .................. .................. .................. ................ 5 12.18 SCADA System ................................................................................................................... 6 12.19 Equipment Redundancy.................. ................. ................. ................. .................. ................ 6

Section 13 Septage & Biosolids Management........................................................ 1

13.1 Septage Management General .......................................................................................... 1 13.1.1 Stabilisation pond................................................................................................................ 1 13.1.2 Wastewater Treatment Plant................................................................................................ 1 13.1.3 Alkali treatment.................................................................................................................. 2

13.2 Biosolids Management - General................. .................. .................. .................. .................. 2 13.3 Sludge stabilization.............. .................. .................. .................. .................. .................. ...... 3

13.3.1 Aerobic digesters................................................................................................................. 3 13.3.2 Anaerobic digesters ............................................................................................................. 3

13.4 Incineration and heat treatment........... ................... .................. .................. ................... ....... 4 13.5 Dewatering.......... .................. .................. .................. ................. .................. .................. ...... 4

13.5.1 Sludge drying beds .............................................................................................................. 5 13.5.2 Vacuum filters, belt filters, belt filter presses, and other mechanical dewatering filters ..... 5

Section 14 Architectural Standards ....................................................................... 1

14.1 General...... .................. .................. .................. .................. .................. .................. ............... 1 14.2 Laboratory control ............................................................................................................... 1 14.3 Roofing Design.................. ................. .................. ................. .................. ................. ........... 1 14.4 Windows.............................................................................................................................. 2 14.5 Doors................. .................. ................. .................. ................. .................. .................. ......... 2 14.6 Ceiling................. ................. .................. ................. .................. .................. ................... ...... 2 14.7 Wall Finishes ....................................................................................................................... 2 14.8 Floor Finishes ...................................................................................................................... 3 14.9 Light Fixtures............... .................. .................. .................. .................. .................. .............. 3 14.10 Landscaping ......................................................................................................................... 3

Section 15 Structural Standards............................................................................. 1

15.1 General...... .................. .................. .................. .................. .................. .................. ............... 1 15.2 Design of Water Retaining Structure.................. ................... .................. .................. .......... 1


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15.3 Construction Requirements.................. ................. .................. ................. .................. .......... 1 15.4 Structural requirements........ .................. ................. .................. ................. .................. ........ 1

15.4.1 Concrete............................................................................................................................... 1 15.4.2 Steel Reinforcement ............................................................................................................ 2 15.4.3 Precast Structural Concrete ................................................................................................. 3 15.4.4 Structural Steel .................................................................................................................... 3

1.4.5 Steel protection.................................................................................................................... 4 15.4.5 Concrete Block Masonry (C.B.M.)...................................................................................... 4

Section 16 Electrical Standards .............................................................................. 1

16.1 General...... .................. .................. .................. .................. .................. .................. ............... 1 16.2 Equipment Identification Nameplates Requirements ................. .................. .................. ..... 1 16.3 Wiring Identification........................ .................. .................. .................. .................. ............ 2 16.4 Panel Boards ........................................................................................................................ 2 16.5 Seismic braces................. .................. .................. .................. .................. .................. ........... 2 16.6 High Efficiency Electrical Motor......................... .................. ................... .................. ......... 2 16.7 Motor Control Centre............... .................. .................. .................. .................. .................. .. 2 16.8 Transformers... ................. ................. ................. ................. .................. ................. .............. 3

16.8.1 High Efficiency Transformers............................................................................................. 3 16.8.2 Distribution Transformers ................................................................................................... 3 16.9 Co-ordination Studies of Protective Devices.................. ................... .................. ................ 3

16.9.1 Co-ordination Studies of Protective Devices Report ........... .......... ........... ........... .......... ...... 3 16.9.2 Short Circuit and Protective Device Evaluation and Co-ordination Study... ........... ........... . 4 16.9.3 Protective Device Co-ordination Study............................................................................... 4 16.9.4 Power System Study Report ................................................................................................ 5 16.9.5 Insulation Resistance Tests.................................................................................................. 5 16.9.6 Lamps.................................................................................................................................. 6

Section 17 Instrumentation & Control .................................................................. 1 17.1.1 Design Criteria .................................................................................................................... 2 17.1.2 Interlocks............................................................................................................................. 2 17.1.3 Field Instrument .................................................................................................................. 3 17.1.4 Indicators............................................................................................................................. 4 17.1.5 Instrumentation Loops (Analogue)...................................................................................... 4 17.1.6 Control Circuits ................................................................................................................... 5 17.1.7 Automation of Treatment Process ....................................................................................... 5 17.1.8 Variable Frequency Drive (VFD) Control..... ........... ........... .......... ........... ........... ........... ..... 6 17.1.9 Pump Control Systems for Wastewater Pumping Stations.... ........... ........... ............ ........... . 7 17.1.10 PLC/RPU Interface.............................................................................................................. 7 17.1.11 Services ............................................................................................................................... 7 17.1.12 Documentation .................................................................................................................... 7 17.1.13 Preventive Maintenance Program........................................................................................ 8 17.1.14 Testing and Commissioning................................................................................................ 9

Section 18 SCADA System ...................................................................................... 1 18.1 SCADA Operating Characteristics ................. ................... .................. ................... ............. 1 18.2 SCADA System Requirements................. .................. .................. .................. .................. ... 2 18.3 SCADA System Control Levels .......................................................................................... 2

18.3.1 Field (Local) ........................................................................................................................ 3 18.3.2 Level 1 Programmable Logic Controller (PLC)............................................................... 3 18.3.3 Level 2 PLANT ................................................................................................................ 3 18.3.4 Screen .................................................................................................................................. 7 18.3.5 Button Bars.......................................................................................................................... 8


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18.3.6 Overview Screens................................................................................................................ 8 18.3.7 Pop-Up Screen..................................................................................................................... 8 18.3.8 Control Pop-Ups Screens..................................................................................................... 9 18.3.9 Information Pop-Ups Screens.............................................................................................. 9 18.3.10 Setpoint Pop-Up Screens................................................................................................... 10 18.3.11 Raw Water Monitoring Parameters (Water).... .......... ........... ........... .......... ........... ........... .. 12 18.3.12 Treated Water Monitoring Program (Water) ..................................................................... 13 18.3.13 Distribution System Monitoring Program (Water)........... ........... ........... ........... .......... ...... 14 18.3.14 Raw Water Monitoring Program (Wastewater)......... ........... .......... ........... ........... .......... ... 15 18.3.15 Treated Water Monitoring Program (Wastewater).. ........... .......... ........... ........... ........... .... 15 18.3.16 Process Parameters Monitoring Program (Wastewater).. ........... ........... ........... ........... ...... 15 18.3.17 Trend Display Requirements ............................................................................................. 16 18.3.18 Water Treatment Plant Operating Statistics............... ........... .......... ........... ........... .......... ... 16 18.3.19 Wastewater Treatment Plant Operating Statistics................ ........... ........... ........... ........... .. 19 18.3.20 Process Control Display .................................................................................................... 20 18.3.21 Standard Colour Convention Process Stream................................................................. 20 18.3.22 Standard Colour Convention Pump/Motor/Valve .......................................................... 21

18.4 Symbols ............................................................................................................................. 22 18.4.1 General .............................................................................................................................. 23 18.4.2 SCADA System Operation Manual Requirements........... ........... ........... ........... ........... ..... 23

18.5 System Architecture............ .................. .................. .................. .................. .................. ..... 27 18.5.1 PLC Program Structure ..................................................................................................... 29 18.5.2 PLC Programming Protocol .............................................................................................. 29

Section 19 Mechanical Standards........................................................................... 1

19.1 General...... .................. .................. .................. .................. .................. .................. ............... 1 19.2 Valves .................................................................................................................................. 1 19.3 Fittings ................................................................................................................................. 1 19.4 Pumps .................................................................................................................................. 2 19.5 Piping & Equipment Identification..... ................... .................. ................... .................. ....... 3

19.5.1 General ................................................................................................................................ 3 19.5.2 Security equipment.............................................................................................................. 4 19.5.3 Piping Identification Labels................................................................................................. 4 19.5.4 Colour Legend..................................................................................................................... 4 19.5.5 Method of Application ........................................................................................................ 6 19.5.6 Sizes of Characters .............................................................................................................. 7 19.5.7 Location of Labels............................................................................................................... 7 19.5.8 Pumps & Valves Colour Schedule ...................................................................................... 8 19.5.9 Nameplates .......... ........... .......... ........... ........... .......... ........... .......... ........... ........... .......... ...... 9 19.5.10 Equipment Name Tags ...................................................................................................... 10

19.6 Equipment....... ................. .................. ................. .................. ................. .................. .......... 10 19.6.1 Bearings............................................................................................................................. 10 19.6.2 Pump Shaft Seals............................................................................................................... 10 19.6.3 Couplings........................................................................................................................... 10 19.6.4 Equipment Guard............................................................................................................... 11 19.6.5 Gauge Taps and Test Plugs ............................................................................................... 11 19.6.6 Alignment.......................................................................................................................... 11

19.7 Equipment Maintenance Requirements ................ ................. .................. ................. ......... 11

Section 20 Ventilating & Air Conditioning Standards......................................... 1

20.1 General...... .................. .................. .................. .................. .................. .................. ............... 1 20.2 VAC System........................................................................................................................ 1 20.3 Minimum Air standard................... .................. .................. .................. .................. .............. 2 20.4 System Redundancy............. .................. .................. .................. .................. .................. ...... 2


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20.5 VAC Control System ........................................................................................................... 2 20.5.1 VAC Master Control ........................................................................................................... 2

20.6 Verification of VAC System............ ................... .................. .................. ................... .......... 2 20.7 Location of air intakes ......................................................................................................... 2

Section 21 Diesel Generator Standard ................................................................... 1

21.1 General...... .................. .................. .................. .................. .................. .................. ............... 1 21.2 Power Supply.... .................. ................. .................. ................. .................. ................. .......... 1 21.3 Approvals............. ................. .................. ................. .................. .................. .................. ...... 1 21.4 Noise Attenuation .................. .................. .................. .................. .................. .................. .... 1 21.5 Diesel Generator Power Requirements..................... .................. ................... .................. .... 2

21.5.1 Water Supply System.......................................................................................................... 2 21.5.2 Wastewater Pumping Station............................................................................................... 2 21.5.3 Ancillary Electrical and Mechanical Equipment .......... ........... .......... ........... ........... ........... . 2

21.6 Diesel Generator System Operation...................... .................. ................. .................. .......... 2 21.7 Diesel Engine Requirements........... .................. .................. .................. .................. ............. 3

21.7.1 General ................................................................................................................................ 3 21.7.2 Flame Detection System...................................................................................................... 3

21.7.3 Fuel System ......................................................................................................................... 3 21.7.4 Speed Governor................................................................................................................... 4 21.7.5 Fuel Tank............................................................................................................................. 4 21.7.6 Oil Lubricating System........................................................................................................ 4 21.7.7 Intake and Exhaust System.................................................................................................. 4 21.7.8 Cooling System ................................................................................................................... 5 21.7.9 Ventilation System .............................................................................................................. 5 21.7.10 Gauges ................................................................................................................................. 5 21.7.11 Battery Start System............................................................................................................ 5 21.7.12 Failure Annunciator............................................................................................................. 5

21.8 Generator Requirements ...................................................................................................... 6 21.8.1 General ................................................................................................................................ 6 21.8.2 Voltage Regulator................................................................................................................ 6

21.9 Control System .................................................................................................................... 6 Section 22 Treatment Plant Operation Manual.................................................... 1

22.1 General...... .................. .................. .................. .................. .................. .................. ............... 1 22.2 Operation Manual Requirements .................. ................... .................. ................... ............... 1 22.3 Format of Operation Manual ............................................................................................... 1 22.4 Water Treatment Plant Operation Manual................ ................... .................. .................. .... 2 22.5 Wastewater Treatment Plant Operation Manual... .................. ................... ................... ....... 4 22.6 Training on the Use of the Operation Manual ................. .................. .................. ................ 8 22.7 Training of WASA Staff .................. .................. .................. .................. .................. ............ 9

22.7.1 Training Provided by the Contractor................................................................................... 9

Section 23 Draughting Standards........................................................................... 1

23.1 Cartographic Production Standards ................... .................. ................... .................. ........... 1 23.2 CAD Standards .................................................................................................................... 6

23.2.1 Types of Drawings .............................................................................................................. 6 23.2.2 Miscellaneous Drawings...................................................................................................... 7 23.2.3 Standards ............................................................................................................................. 7

23.3 Survey Drawings...................... ................. .................. ................. .................. ................. ... 10 23.4 Land and Engineering Surveying......................... .................. .................. ................. ......... 10 23.5 Electrical Engineering Works................ .................. .................. .................. .................. .... 14


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23.5.1 Schematics......................................................................................................................... 15 23.6 Sketches ............................................................................................................................. 16 23.7 Symbology......................................................................................................................... 18 23.8 10 Golden Draughting Rules ............................................................................................. 28 23.9 Standard Title Block Data Entry....... .................. .................. .................. .................. ......... 28

23.9.1 Project Title....................................................................................................................... 28 23.9.2 Job Title............................................................................................................................. 28 23.9.3 Sheet.................................................................................................................................. 28 23.9.4 Drafted By ......................................................................................................................... 28 23.9.5 Designed By ...................................................................................................................... 29 23.9.6 Checked By ....................................................................................................................... 29 23.9.7 Approved By ..................................................................................................................... 29 23.9.8 Scale .................................................................................................................................. 29 23.9.9 File Path............................................................................................................................. 29

23.10 File naming convention ..................................................................................................... 29 23.10.1 General Name.................................................................................................................... 30 23.10.2 Block Name....................................................................................................................... 30 23.10.3 Main CAD Types .............................................................................................................. 31 23.10.4 Architectural...................................................................................................................... 32

23.10.5 Schematic .......................................................................................................................... 33 23.10.6 Survey................................................................................................................................ 34 23.10.7 Engineering ....................................................................................................................... 35 23.10.8 Electrical............................................................................................................................ 36


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List of Abbreviations

AI Analogue Input

AO Analogue Output

ANSI American National Standard Institute

ARI Air-Conditioning and Refrigeration Institute

ASHRAE American Society of Heating, Refrigerating and Air-conditioning Engineers

AWWA American Waterworks Association

CAD Computer Aided Design

CIBS The Chartered Institution of Building Services

CPM Critical Path Method

CV Curriculum vitae

CVS Certified Value Specialist

DI Digital Input

DO Digital Output

DTC Direct Torque Control

EA Environnemental Analysis

EIA Environmental Impact Assessment

EPA Environmental Protection Act

FAT Factory Acceptance Test

FIDIC Federation Internationale Des Ingenieurs Conseils(International Federation of Consulting Engineers)

HAZOP Hazard and Operability Study

HFS Hydrofluosilicic Acid

HLPS High Lift Pumping StationI&C Instrumentation and Control System (I&C)

I/O Input / Output

LOH Loss of Head

MCC Motor Control Centre


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MoWT Ministry of Works and Transport

MoALMR Ministry of Agriculture, Land and Marine Resources

EMA Environmental Management Agency

MoH Ministry of Health

MoPD Ministry of Planning and Development

MoPUE Ministry of Public Utilities and the Environment

NSF National Sanitation Foundation

NTU Nephelometric Turbidity Units

P&ID Proportional and Integral Derivative

PDR Pre-Design Report

PID Proportional Integral Derivative

PLC Programmable Logic Controller

QA Quality Assurance

QC Quality Control

RFP Request for Proposal

RIC Regulated Industries Commission

RPU Remote Processing Unit

SAT Site Acceptance Test

SCADA Supervisory, Control and Data Acquisition

SMACNA Sheet Metal and Air Conditioning Contractors' National Association

SPMDD Standard Proctor Maximum Dry Density

THD Total Harmonic Distortion

TKN Total Kjeldahl Nitrogen

TTBS Trinidad & Tobago bureau of Standards

UV Ultra Violet

VAC Ventilation and Air Conditioning

WASA Water and Sewerage Authority of Trinidad & Tobago

WTP Water Treatment Plant

WWTP Wastewater Treatment Plant

WHO World Health Organisation


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Water And Sewerage Authority (WASA)Water and Wastewater Design Guideline Manual General Information

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Section 1 General Information

As Trinidad & Tobago moves toward a 2020 vision of a modern and developed country, new andrefurbished water and wastewater infrastructures are needed all around the islands. The Water

And Sewerage Authority (WASA) of Trinidad and Tobago has put together this document inorder to guide the engineering design and establish the recommended standards for all new waterand wastewater infrastructure.

WASA has the responsibility for the provision of water supply and sewerage services in Trinidadand Tobago, under Water and Sewerage Act, chapter 54:40. Increasing the levels of service

provided to the population has been a continuous concern for WASA. The present guidelines areadapted to Trinidad and Tobagos context and are compatible with WASAs long termoperational policies. They present a comprehensive document for the construction andrehabilitation of new and existing water and wastewater infrastructures.

The 2020 vision requires capital works from the government of Trinidad & Tobago in order tomeet the goals set. The implementation of water, wastewater and linear services projects requiresthe services of Consultants to provide the required engineering expertise in accordance with therequirements as specified herein. Consultants should therefore familiarize themselves with theseguidelines and provide their services accordingly to meet WASAs expectation.

These guidelines are primarily intended to outline acceptable levels of servicing and minimumcriteria for future infrastructure in Trinidad & Tobago. They will assist consulting engineers, Wstaff and other designers in the preparation of water and wastewater system infrastructure design.Some of the design standards, detailed herein this manual, are not currently used by WASA inthe implementation of water and wastewater projects. However the information contained hereinwill serve as a preliminary basis for consideration by WASA and should be followed.

This Water and Wastewater Design Criteria Manual is the property the Water And SewerageAuthority (WASA) of Trinidad and Tobago. The design guidelines as detailed herein are for theimplementation of water and wastewater projects, including linear services and treatment plants.

The stipulated design guidelines must be complied with unless dispensation has been obtained inwriting from WASA or specified in the Request for Proposal. These variations from theguidelines should be determined on a project by project basis during scope negotiations betweenthe Designer and WASA.

Other References

This manual shall be used in conjunction with:

1. All rules, laws and regulations of the Republic of Trinidad and Tobago

2. Projects Tender documents

3. WASA requirements and standards

4. Policies and Guidelines from stakeholders


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Section 2 Design Approach & Approvals

2.1 Introduction

These guidelines do not supersede nor replace any legislation governing the design of suchtreatment plants. Options and design optimisation are still to be conducted and investigated at the

prefeasibility level. The Consultants must be fully familiar with Trinidad & Tobago legislationswith respect to the design of water and wastewater infrastructure.

The guidelines and standards, as provided herein, were set by WASA in order to guide and framethe engineering and consultancy works and assure a standardised and adequate design level in theimplementation of such systems. Approvals by WASA of infrastructures will require complianceto these guidelines in conformity with WASAs Water and Wastewater Policies.

Since standards, technology and priorities evolve, this manual is aimed to be reviewed frequentlyand consultants are to assure that they are using the latest revision.

2.1.1 Multi barrier approach

In conformity with WASAs policies, in order to ensure clean, safe and reliable drinking water, amulti barrier approach is to be implemented from the source all the way to the consumer's tap.This requires an understanding of the general characteristics of the water, the watershed or landsurrounding the water source, as well as mapping all the potential threats to the water quality.The approach of the required design is to provide for barriers to either eliminate the threats orminimize their impact. It includes protecting the available source from contamination, usingeffective water treatment, and preventing water quality deterioration in the distribution system.Together the barriers work to provide greater assurance that the water will be safe to drink.

2.1.2 Sustainable development

An integrated water resources perspective ensures that social, economic, environmental andtechnical dimensions are taken into account in the management of water resources. WASAwishes to promote practices that encourage sustainable development so there wont be anycompromising of future generations ability to meet their needs.

As examples, protection of wells head, installation of domestic water meters, and settingwastewater effluent standards are part of the sustainable approach provided in this manual.These are some of the good practices needed to assure long term sustainable and valuable waterfor Trinidad & Tobago.

The water treatment standards and guidelines are established to ensure production of safedrinking water. The amount and minimum scale of treatment processes are based on type andquality of raw water, including their variability.

2.2 Design GuidelinesThis manual provides details on the design of water and wastewater related infrastructure so thata standard of quality, reliability and uniformity will be achieved for WASA services to the


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population of Trinidad & Tobago. It covers a wide range of applicable standards andcharacteristics that need to be considered in order to assure the minimal quality requested. Itemscovered by this manual include the following:

1. Equipment redundancy2. Architectural standard

3. Structural standard

4. Underground pipelines

5. Electrical standard

6. Mechanical standard

7. Instrumentation & control standard

8. Emergency standby diesel generator standard9. Equipment coding system standard

10. Operation & maintenance manual standard

11. Water quality and treatment standard

12. Wastewater effluent and treatment standards

13. SCADA

2.3 Review process of the guidelinesAs technology, exigencies and standards evolve; these guidelines will have to be submitted for aregular review by WASA in order to reflect the latest findings and comments. It is recommendedthat this document be revised at minimum every five (5) years to comply with the best interest ofthe population of Trinidad & Tobago.

2.4 ApprovalsThe Consultants shall comply with, and shall conduct all work with cognisance given to allrelevant statutory regulations and requirements, and where required, shall apply for all relevant

approvals or certificates.In all cases, the Water and Sewerage Authority (WASA) should have granted approvals on theoutline and details of all projects prior to the installation of any facility. The WASAsadministrative procedures are part of another document that must be consulted.

In addition, all projects must meet Environmental Management Authority (EMA) approvals byobtaining a Certificate of Environmental Clearance (CEC). Depending on the type of project, anEnvironmental Impact assessment (EIA) may be required as established by EMA.


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The Consultants shall comply with other stakeholders Policies and Rules, or tender documents.They shall prepare all required documents for submission and review with WASA.

The Consultants must deliver to WASA a status report of all the applications for approvalsrequired for the project. Where there are outstanding approvals, the Consultants shall indicate thetime frame within which these approvals are expected to be in place.

Consultants are responsible for ensuring that plants designed by them comply with Acts, Codes,Standards and Guidelines. The Standards and Guidelines provided in this manual are intended toset the minimum acceptable standard and not to relieve them of their responsibilities to complywith their legal and contractual requirements and obligations.

For detailed information about WASAs administrative procedures for review, including costs,type and number of copies of documents to submit for approval, consult WASAs approval

process documentations.


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Water And Sewerage Authority (WASA)Water and Wastewater Design Guideline Manual Design Standards

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Section 3 Design Standards

3.1 Design requirements

It is the Consultants responsibility to ensure that they have fully understood the requirements of the project as detailed in the Request for Proposal as they will be required to fulfil the specified scopeof work.

The infrastructure work includes both water and wastewater projects. WASA retains the services ofConsultants to provide the required engineering expertise to implement these projects in anintegrated manner with all building, safety and quality requirements. WASA requires and expectsthat the Consultant will comply with the requirements as specified herein and therefore providetheir services accordingly to meet this expectation.

All materials and equipment supplied shall be suitable for being delivered, store and operated undertropical conditions of high temperature, high humidity, heavy rainfall, mildew and fungus

conductive environment.All WASA buildings or structures shall be flood proof. The site for the new facility shall beappropriately selected or designed to be above the 20 years recurrence interval flood line.

When standards are provided, they are minimum requirements to be met by the system. Whenspecified, these standards are mandatory unless otherwise specified in writing by WASA.Mandatory standards include drinking water quality standards and wastewater treatment planteffluent standards.

3.2 Acts, Codes and Standards

The design of infrastructure shall comply with the following regulations, Acts, Codes, Standards,Guidelines for all projects undertaken by Consultants on behalf of WASA:

1. Environmental Management Authority (EMA) of T&T

2. Water And Sewerage Authority (WASA) of Trinidad and Tobago

3. Ministry of Public Utilities and Environment (MoPUE)

4. National Building Code

5. National Fire Code

6. OSHA

The standards specifications for materials should be consistent with the requirements of thefollowing:

1. Trinidad and Tobago Standards (TTBS)

2. International Standards (ISO)

3. North American Standards (ANSI/AWWA)

4. British Standards (BS)


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3.3 Other Design & Construction StandardsConsultants shall comply with all Trinidad & Tobago technical rules and regulations related to thedesign and construction of treatment plants as well as linear services.

Stakeholders if applicable should be included in the design. The T&T water and wastewaterstakeholders include but are not limited to:

- Ministry of Public Utilities- Town and Country Planning Division- Environmental Management Authority (EMA)- Ministry of Local Government- Ministry of Works and Transport- Ministry of Finance- Ministry of Health- Regulated Industries Commission- Ministry of Agriculture, Land and Marine Resources- Office of the Ombudsman (Ministry of Legal Affairs)- Consumer Affairs Division (Ministry of Legal Affairs)- Water Recourses Agency and Forestry Division- Trinidad & Tobago Fire Services

3.4 Industry StandardsAll materials for potable water and sewers shall meet the ASTM, AWWA or other approvedequivalent standards. The Standards also provide literature on Workmanship. The followingstandards are listed for guidance and are not final or exclusive to other standards.


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Storage Tanks

Welded Steel TankPainting for Welded Steel TanksFactory Coated TanksDisinfectionConcrete Structures for Retaining Liquids

ANSI/AWWA D100-84ANSI/AWWA D102-78ANSI/AWWA D103-80ANSI/AWWA D652-86AS 3735 1991

Pipelines

Polybutylene (PB)Polyethylene (PET)Poly Vinyl Chloride (PVC)Fabricated Steel Pipe and FittingsSteel Pipe Flanges Class DCoal tar protection coatings and linings for steel water

pipelinesFlanged Ductile Iron PipelinesRubber GasketDisinfectionPressure TestGrey Iron CastingGRP

Elastometrix Joint Rings for pipework and pipelines

Flanges and bolting for pipes valves and fittings metricseries(copper alley and composite flanges)

Metal Washers for General Engineering PurposesMetric Series

Specifications for Poly Vinyl Chloride (PVC) SolventCement for use with unplasticized PVC Pipes andfittings for cold water applications

Cast Iron Non-pressure pipes and pipe fittings metricunits

AWWA C-902-78AWWA C-901-78AWWA C-900-75AWWA C-208-83AWWA C-207-86AWWA C-203-86

AWWA C-115/A21AWWA C-111/A21AWWA C-651-86AWWA C-600-82BS 1452:1977

AWWA C 950 - ASTM D 3754

BS 2494:1986

BS 4504: Part 2 1974

BS 4320:1968

TTS 413-1992

AS 1631-1974


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Valves

Ball Valves

Rubber Sealed Butterfly Valves

Sluice Valves

Predominantly key Operated Cast Iron Valves forWaterworks purposes

Butterfly Valves

Copper Alloy Gate Valve and Non-Return Valves foruse in water supply and hot water services

Float Operated Valves

Specifications for Piston Type Float Operated valves(Copper Ally Body) (Excluding Floats)

Specifications for Diaphragm type float operated valve(copper Alloy Body) (Excluding Floats)

Specifications for Diaphragm type operated valves plastic bodies, for cold water services only excludingfloats

Draw off taps and stop valves for water services (screwdown pattern)

AWWA C-507-85

ANSI/AWWA C-50

AWWA C-501-86

BS1 5163:1986

BS 5155:1984

AS 1628:1977

BS 1212

PT 1 1990

PT 2 1990

PT 3 1990

BS 1010 PT 2 1973

Safety Valves

Safety Valves

Specification for safety valves for steam and hot water

BS 6759

PT 1 1984

Mixing Valves

Mixing Valves

Non-Thermostatic, Non-Compensating mixing valves

Specification for Thermostatic mixing valves

BS 1415

PT 1 1976

PT 2 1986


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Various standards

Glass Filament reinforced thermosetting plastics (GRP)Pipes Polyester Based-Water Supply. Sewerage andDrainage Applications

Water Supply Metal Bodied Taps Specified by performanceWater Well Casing

Specification for steel tubes for casing

Specification for thermoplastics tubes for casing andslotted casingStationary circulation pumps for heating and hot waterservice system

Specification for Cold Water Storage and combinedfeed and expansion cisterns (polyolefin or olefincopolymer) up to 500L capacity used for domestic

purposes

Multi StandardMeasurement of flow of cold potable water in closedconduits

Safety and control Devices for use in hot water systems

Code of Practice for test pumping of Water Well

Storage Cisterns up to 500L Actual Capacity for watersupply for domestic purposes

Bitumen based coatings for cold application, suitablefor use in contact with potable water

Bitumen based hot applied coating materials for

protecting iron and steel including suitable primers wererequired

Water Quality (Multi Standards) Physical, Chemical andBiochemical methods

AS 3571 1989

AS 3718 1990

BS 879

PT 1 1985

PT Z 1988

BS 1394

BS 4213 1991

BS 5728

BS 6283

BS 6316 1992

BS 7181 1989

BS 3416 1980

BS1 4147 1980

BS 6008PT 2


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Water Meters

Cold Water Meters Multi Jet Type ANSI/AWWA C 708-82

Cold Water Meters Displacement Type

Cold Waters Turbine type for customer service

Filtering materialMeters for cold potable water

ANSI/AWWA C 700-7

ANSI/AWWA C 701-78

ANSI/AWWA B 100AS 3565 - 1988

Water Sampling

Water Quality Sampling Pt 1 Guidance onDesign of Sampling Programmes 13 pPT 2 Guidance on sampling techniquePT 3 Guidance on the Preservation and

handling of samplesPT 6 Guidance on sampling of rivers andstreamsPT 8 Guidance on sampling of WetdepositionsPT 9 Guidance on sampling from marinewatersPT 10 Guidance on sampling of waste watersPT 11 Guidance on sampling of Ground waters

ISO 5667 1980

ISO 5667 1991ISO 5667 1987

ISO 5667 1990

ISO 5667 1993

ISO 5667 1992

ISO 5667 1992ISO 5667 1993

Water Testing of Pipes

Methods of test for unplasticized polyvinyl chloride(PVC) Pipes. PT4 - Effects of Sulphuric Acid Requirements and Test method

Method of test for unplasticized PVC pipes and fittingsPT 3 - Determining the fracture toughness of UPVCPipes

Methods of test for unplasticized PVC pipes

PT8 - Method for Hydrostatic pressure testing of UPVCshort term test

Methods of test for unplasticized PVC Pipes PT 9 -Methods of test for hydrostatic pressure testing ofUPVC pipes long term test

Methods of test for unplasticized polyvinyl chloride(PVC) Pipes PT 7 - resistance to external blows

TTS 16 80 30PT 4 - 1991

TTS 16 80 30PT3 - 1991

TTS 16 80 30PT8 - 1991

TTS 16 80 30PT9 - 1991

TTS 16 80 30PT7 1991


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Wastewater systems

CementAggregateSteel (Reinforcer)Structural SteelManhole BricksPrecast Sections

Manhole Frames ConesReinforced Concrete Pipes

Non reinforced Concrete PipesWelded Steel PipeSteel Fitting CouplingsGate ValvesSluice ValvesDrain Pipes and FittingsSewer

Grey ironDuctile IronThermoplastic Pipe for SewersThermoplastics waste pipes and fittingsPolypropylene Waste pipe and fittings(external Diameter 34.6 mm 41.0 mm 54.1mm)Unplasticized PVC (UPVC) Pipes and Fittings for stormand surface water applications

Unplasticized PVC (UPVC) Pipes and Fittings for soilwaste and vent (SWV) applicationsDesign charts for water supply and sewerageWater supply Mechanical backflow preventiondevicesPlastics Waste FittingsSpecifications for compact type float operated valves forWC Flushing Cisterns (including floats)

Specification for Galvanized low Carbon Steel, Cisterns,lid tanks and Cylinders

Specification for unplasticized PVC Drain, Waste andvent pipesTechnical Drawing Installation, Graphical symbols forsupply water and drainage systems

ASTM C-150 -60ASTM C-33-59ASTM A-15-58TASA-ASA A57 1-1952ASTM C-32-58 Grade MAASTM C-478-61T usinaType II cementASTM A48-60TASTM C76-60TASTM C14-59, lAWWA C 202-59AWWA (Same as Water)ASA B16 10-1957AWWA C 501-41TBS 4660BS 4660, BS 5481 or ClassB, BS 3505BS 4622BS 4772ASTM D 2321, F-894BS 5255 1989BS 5254 1976

AS 1254

AS 1415 PT 1-4

AS 2200-1978AS 2845-1986

AS 2887 1986PT 4 -1991

BS 417

TTS 414-1992

TTS 31 85 006PT 6 1998

Recommendations for the Design of buildings, plumbing and drainage systems

TTS 16 90 400PT 4 - 1985


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pressure reducing valves and water tanks do not require redundancy. See section 7 for moredetails.

Main water trunk systems should allow for some level of redundancy by aiming for smallerdouble parallel pipe layout with adequate valving rather than one large pipe diameter.

4.4 Standby PowerWhenever feasible, power supply to WASAs plants shall be provided with dual feed from the

power supply grid network. Where this is not possible, standby power shall be provided in thefollowing key process system:

- Wastewater treatment plant- SCADA System- Plant VAC System- Plant disinfection system- All equipment required to enable effective treatment for plants discharging in

environmentally sensitive areas.

- Water intake pumps and equipment- Water Treatment Plant- All equipment that is required to be operational to enable the water treatment plant to

meet average day demand is to be provided with standby power or an alternate source of power.

- Potable Water Pumping Station on main trunk systems. Other pumping stations shall beassessed to establish criticality based on network configuration, gravity feed reservoirs,type of supplied customers etc.

- Wastewater Pumping Station

Power ratings for standby power are defined by ISO 8528-1 as the power available in the eventof a main power network failure up to a maximum of 500 hours per year of which up to 300hours may be run continuously. Load factor may be up to 100% of standby power. No overloadis permitted.

4.5 Standardization of EquipmentConsultants shall ensure that the selection of equipment for use in the plants shall be standardizedas much as possible. In all cases, consultants must first refer to WASAs available list ofapproved suppliers and manufacturers for each application. For each process, the variety of majorequipment manufacturers should be limited to a maximum of three. The advantages of keepingthe selection of equipment to a maximum of three are:

- Reduction of time required to review design information


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- Minimize the inventory of spare parts- Reduction of time for staff to become fully familiarized with new equipment and facility- In general, consideration shall be given for new equipment to be from the same

manufacturer as those that are already installed in the same unit process train. This

requirement will be reviewed at the detailed design stage and alternate equipment ortechnology will be considered at that time.

- Approved and alternate equipment shall be specified in the tender document such thatWASA has the right to accept or reject any equipment that the Contractor proposes tosupply under the contract.


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Section 5 Design of Water Distribution System

5.1 General Requirement

This section outlines the requirements for the design of water supply systems. However, theConsultants shall apply sound engineering judgement and approach to the design of suchsystems. All designs shall comply with Trinidad & Tobago National Plumbing Code, AWWAStandards of Practice and Specifications, relevant codes or design guidelines. The designs mustas much as its applicable, include mechanism for water conservation, including but not limitedto pressure control devices, low flush toilets, low volume faucets, etc.

Notwithstanding the above, the Consultants shall be familiar with the policy and standardsrelated to fire protection services requirements in Trinidad & Tobago.

In all projects, assessment of trenchless construction techniques and rehabilitation methods forexisting pipes shall be thoroughly prepared. The assessment shall as a minimum cover thegeotechnical conditions, traffic disruptions, survey the existing utilities and sub surfacestructures, obtain right-of-way and property line information, take account of possibleimprovements to street or utilities, risk and safety, and include technology aspects onconstruction and costs etc.

For all new communities, the Consultants shall establish the geodetic invert elevations and ties ofall water service connections at the street line. All of this information shall be incorporated on theAs-built plans. To avoid proliferation of booster stations and reservoirs within eachdevelopment, each project should be assessed through modelling of regional network andoptimum development scheme. WASAs Master Plan for Trinidad & Tobago should be reviewedto grasp the bigger communities and regional planning priorities.

5.2 Water DemandIn the past years, many studies have been undertaken to assess the water demand for the differenttypes of consumers in Trinidad & Tobago. The available information is usually scarce andsignificant variations exist between the different studies. The following design criteria for waterdemands is based on different sources, notably the 1994 Project Memoranda on Existing andFuture Demands by William Halcrow & Partners Ltd., the 2006 Analysis and Estimation ofWater Demand Forecasts by Gordon Wyke, and various international figures including Britishand North American standards.


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5.2.1 Design Water Demand

The system shall be designed to meet the greater of either of the following demands:

1. Maximum Daily Demand Plus Fire Flow

2. Maximum Hourly Demand

Where applicable, individual studies shall be conducted for the following:

1. Special commercial establishments and major commercial areas

2. Special industries and major industrial areas

3. Institutional development

4. High density residential areas


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5.2.2 Average Water Demand (light industrial and commercial)

If individual data is not available, the following typical numbers should be used in order toestablish the daily average flow demand for light commercial and industrial facilities (sources :WASA, Metcalf & Eddy) :

Facilit

WASA Design Manual Final SN Mar 09

Documents

Transcript of WASA Design Manual Final SN Mar 09