NIUE DRINKING WATER SAFETY PLAN DRAFT 3.0 Formatted: Font color: Auto April 2009 Document Check Version No. Date revised: Revised by: Andre Siohane Author(s): Date finalised November 2008 Clinton Chapman Document Date: Reviewed by: Approved by: Date: i The Government of Niue This document was compiled by the Division of Water Supply for more effective management of Niue’s water supply. The Department of Public Works is responsible for the implementation and oversight of this plan. This plan is due for revision in November 2009. This document is an output of a regional programme funded by AusAID, for effective management of drinking water supplies in Pacific Island Countries. ii TABLE OF CONTENTS SECTION 1 INTRODUCTION................................................................................................................................1 1.1 Niue Drinking Water Supply...............................................................1 1.2 Water quality surveillance and monitoring .........................................2 1.3 The need for a Drinking Water Safety Plan .......................................2 1.3.1 The Drinking Water Safety Plan approach .................................3 1.4 Development of the DWSP................................................................3 1.5 Using the Plan ...................................................................................3 SECTION 2 ORGANIZATIONAL DETAILS...........................................................................................................4 2.1 Supply Name .....................................................................................4 2.2 Supply Owner ....................................................................................4 2.3 Person(s) responsible........................................................................4 2.4 Source ...............................................................................................4 2.5 Treatment ..........................................................................................4 2.6 Distribution zone(s)............................................................................4 2.7 Level of Service .................................................................................5 2.8 Use and Users...................................................................................5 2.9 Population served..............................................................................5 SECTION 3 NIUE DRINKING WATER SUPPLY DESCRIPTION......................................................................... 6 3.1 Catchment & Source .........................................................................6 3.1.1 Geography and Geology ............................................................6 3.1.2 Hydrogeology .............................................................................6 3.1.3 Soils............................................................................................7 3.1.4 Climate .......................................................................................7 3.1.5 Land-use & Vegetation ...............................................................7 3.2 Intake & Treatment ............................................................................9 3.2.1 Intakes........................................................................................9 3.2.2 Water Supply Systems .............................................................10 3.2.3 Submersible Pumps .................................................................11 3.2.4 Treatment .................................................................................12 3.2.5 Monitoring Bores ......................................................................12 3.3 Storage............................................................................................12 3.3.1 Storage Tanks ..........................................................................12 3.4 Distribution.......................................................................................14 3.4.1 Pressure Pumps.......................................................................14 3.4.2 Pressure Vessels......................................................................14 3.4.3 Mains Pipe-work.......................................................................14 3.4.4 Leak Detection .........................................................................14 3.4.5 Service Lines and Domestic Pipe-work ....................................15 3.5 Water Demand Management...........................................................15 3.6 Water Quality...................................................................................15 3.7 Staff and Human Resources............................................................15 SECTION 4 RISK ASSESSMENT...................................................................................................................... 17 4.1 Background .....................................................................................17 4.2 Methodology ....................................................................................17 iii 4.3 Summary of risks.............................................................................17 4.3.1 Catchment....................................................................................17 4.3.2 Source..........................................................................................18 4.3.3 Pumps..........................................................................................19 4.3.4 Treatment.....................................................................................19 4.3.5 Reservoirs (Tanks).......................................................................19 4.3.6 Pipeworks ....................................................................................19 4.3.7 Backflows.....................................................................................20 4.3.8 Illegal Connections.......................................................................20 4.3.9 Natural disasters ..........................................................................20 SECTION 5 DRINKING WATER SAFETY PLAN...............................................................................................29 5.1 DWSP Tables ..................................................................................29 5.2 Hazard.............................................................................................29 5.3 Hazardous Events ...........................................................................29 5.4 Priority .............................................................................................29 5.5 Control Measures ............................................................................30 5.6 Improvements..................................................................................30 5.7 Monitoring........................................................................................30 5.7.1 What to monitor?..........................................................................30 5.7.2 What is the Critical Limit?.............................................................30 5.7.3 Who should monitor? ...................................................................30 5.7.4 How often?...................................................................................30 5.8 Corrective or remedial action...........................................................30 SECTION 6 MONITORING SCHEDULE.............................................................................................................41 6.1 Visual Inspection Catchment ...........................................................41 6.2 Water Quantity Check Catchment ...................................................41 6.3 Water Quality Checks......................................................................42 6.4 Water Quantity Checks....................................................................42 6.5 Visual Inspections – Production Bores ............................................42 6.6 Visual Inspections – Storage Reservoirs .........................................43 6.7 Visual Inspections – Pressure Pump ...............................................43 6.8 Visual Inspections – Pipe Works .....................................................44 SECTION 7 IMPROVEMENT SCHEDULE.........................................................................................................45 SECTION 8 REVIEW ........................................................................................................................................49 APPENDIX: WATER AND PUBLIC HEALTH ...........................................................................................................50 Microbial Agents.........................................................................................50 Chemicals ..................................................................................................50 Physical Problems......................................................................................50 Testing the Water.......................................................................................50 Hardness....................................................................................................51 iv LIST OF TABLES Table 1: Production Bores in Niue......................................................................................Error! Bookmark not defined. Table 2: Storage tank summary.........................................................................................Error!