Twenty Minutes on Preparation and Implementation of Water Safety - - PowerPoint PPT Presentation

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Twenty Minutes on Preparation and Implementation of Water Safety Plan for Nagpur

Pawan Labhasetwar Scientist & Head, Water Technology & Management Division CSIR-NEERI, Nagpur

Outline of presentation

• Introduction to water safety plan
• Water safety plan – Case study of Nagpur

– Catchment – Source – Treatment – Storage – Distribution – Households

• Take away

3 Yarra Valley Water Ltd

What is a Water Safety Plan?

Consumer system Distribution system Water resources & sources Treatment

A documented plan that:

• Identifies hazards, assesses risks from catchment to consumer
• Prioritises risks and focus on highest risks
• Mitigates risks through control measures

Meaning:

• Less output monitoring (final water)
• More input monitoring (is the system working?)

Water Safety Plan Implementation

Study Area – Nagpur

• Area : 217 km2
• Population: 2.5 million (2011)
• Water supply regulated by

Nagpur Municipal Corporation (NMC) and operated by Orange City Water Private Limited (OCW)

• >90% coverage
• 350,000 connections
• 650 MLD treated water
• 50% non-revenue water
• 25% population < 135 lpcd
• 4-24 hours supply

Step 1. Assemble the WSP team Step 2. Describe the water supply system Step 3. Identify hazards and hazardous events and assess the risks Step 4. Determine and validate control measures, reassess and prioritize the risks Step 5. Develop, implement and maintain an improvement/upgrade plan Step 6. Define monitoring of the control measures Step 7. Verify the effectiveness of the WSP Step 8. Prepare management procedures Step 9. Develop supporting programmes Step 10. Plan and carry out periodic review of the WSP Step 11. Revise the WSP following an incident

A step-by-step Approach For WSP

Water System Elements - Catchment

Extraction Storage Watershed Treatment Water meter Households Distribution

Totladoh Dam

Pench Khairi Reservior

Mahadula Pumping Gorwada Lake

Totladoh Dam

Pench Khairi Reservior

Mahadula Pumping Gorwada Lake Pench 4 WTP

Pump House BPT 2300 mm Line

7.6 mg/l fluoride

Catchment

WSP team assisted in identifying ash pond contamination

Immediate communication between stakeholders– WTP

• perator and power plant
• perators (MAHAGENCO)

Zoo activities shifted outside the catchment

Catchment

Water System Elements- Treatment Plant

Extraction Storage Watershed Treatment Water meter Households Distribution

Unregulated Flow of PAC Dose at Gorewada Treatment Plant

Aquatic Weeds in Clarifier at Old Gorewada Treatment Plant, Nagpur

Hazardous events Identified Control Measures Enacted No coagulant dose Coagulation with PAC being done, with mixing ensured by turbulence due to baffles provided at inlet channel Algae in raw water Pre-chlorination done with appropriate dosing and periodic cleaning Poor operation and maintenance All electrical and mechanical equipment have been taken under monthly preventive maintenance contract. Malfunctions are reported immediately and addressed.

Treatment Old Gorewada WTP

Water System Elements - Storage

Extraction Storage Watershed Treatment Water meter Households Distribution

Broken Inlet Chamber of Master Balancing Reservoir at Seminary Hill

Leakage from Inlet Valve of Master Balancing Reservoir at Seminary Hill

By-pass valves installed at reservoirs to facilitate cleaning and repair

Storage

Water System Elements - Distribution

Extraction Storage Watershed Treatment Water meter Households Distribution

Modern Risk Management Principles – IRA-WDS

Take measures to prevent contamination Improved Quantity Management Reducing leakage Improved Water Quality Management

Focus on : Water Distribution System (WDS)

Determine how contamination may arise

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Risk Assessment Study for Contaminant Intrusion

Pipe condition Assessment Model (PCA) Contaminant Ingress Model (CIA) Risk Assessment Model (RAM)

3 Modules of IRA-WDS

Selection of Study Area for Risk Assessment Study of WDS

Reshimbagh Study Area with Road Network

1. Nagpur Municipal Corporation (Reshimbagh Office) 2. DRA Consultancy 3. Field survey

Data Collection

Water Supply Network Sewer and Drain Network

GIS Mapping

Attribute data Installation year, Diameter, Material, Length, Locations of valves, Bury depth, Manhole No., Ground elevation etc.

AutoCAD Maps : DRA consultancy (NMC)

Installation Year Traffic Diameter Pipe Material

Analysis of Data on Pipe Breakages

No of Breaks = 107 No of Bursts = 81 No of Breaks in pipes = f(Installation Year, Traffic load) No of Bursts in pipes = f(Installation Year, Material type)

Source : NMC Local Authorities

• 1. Very High Risk
• 2. High Risk

GIS Mapping & Risk Assessment

WS Pipe ID: 1141 Material: CI Diameter: 100mm Installation year: 1980 Traffic: Quiet Leakage: 0.08 lps Pipe Condition: Good WS Pipe ID: 1135 Material: CI Diameter: 100mm Installation year: 1980 Traffic: Busy Breakage: 2 /year Bursts: 2 /year Leakage: 0.21 lps Pipe Condition: Bad

WS line passing through zone of contamination due to open drain and sewer crossing

High Risk due to Bad Pipe Condition

2 Leakage points Pressure measurement points

Pressure and leakage monitoring

Water quality testing for various Physico-chemical and microbial parameters at Reshimbagh and Wanjari Nagar

• At ESR
• At critical locations in distribution system
• At Consumer end

(critical locations of Chandan Nagar and Siras Peth)

Water Storage tanks

Sampling Area Siras Peth Chandan Nagar Sample Id SP-1 SP-2 SP-3 CNPT-1 CNPT-2 CNPT-3 CNPT-4 Temp (OC) 29.4 30.4 30.2 31.1 31.1 31.1 30.8 pH 8.4 8.1 8.3 7.8 8.1 7.9 8 EC (µS/cm) 286 294 285 269 245 249 242 TDS (mg/L) 171.6 176.4 171 161.4 147 149.4 145.2 Turbidity (NTU) 0.4 0.8 0.2 9 1 1.8 1.3

• Res. Cl

(ppm) <0.1 0.1 0.1 0.1 Total Hard (mg/L) 108 108 112 126 96 69 104 Ca Hard (mg/L) 72 70 72 72 64 64 68 Mg Hard (mg/L) 36 38 40 54 32 32 36 Total Alk (mg/L) 166 184 180 196 176 168 164 Chloride (mg/L) 23 18 42 33 32 28 34 TC (CFU/ 100ml) ND ND ND 7600 ND 1040 ND FC ND ND ND 6000 ND 126 ND FS ND ND ND 50 ND 96 ND

Physico-Chemical and Microbial Analysis: Consumer end samples

 550 km pipeline has been laid using HDD technology to speed up laying of pipeline. HDPE pipes will eliminate the problem of water pilferage Repair and upgradation of existing system in pilot area resulted in longer supply hours and improved water quality.

Distribution Control Measures

Water System Elements- Households

Extraction Storage Watershed Treatment Water meter Households Distribution

10 20 30 40 50 60 70 80 90 CFU/100ml

Average FC Count At Different Locations From Source to P-O-U

A yes answer is interpreted as a risk Question asked : Yes answer

 Is storage design for dipping: 88%  Do they use dipper with short/no handle: 67%  Is the vessel accessible for children: 58%  Do they pour back excessive water: 43%  Is the vessel made of non-durable material: 33%  Do they lack lid on storage vessel: 17%  Is the inside of the vessel hard to clean: 13%  Are there signs of dirt around opening: 11%

The three most common risks are :

1. Storage designed for dipping 2. Use of short/no handle or hand for extraction 3. Storage vessels accessible for children. Unimproved storage, poor handling habits, unsafe extraction which could be a pathogen entrance route.

Sanitary Survey at Select Households

Risk Matrix

Catchment Treatment Plant Distribution

Storage

Total Hazards Identified – 109 + 13

SURFACE WATER 28 42 13 16 7 28 8 13

Consumer

10 ? 2 8 3

Earlier identified Earlier addressed New addressed New identified

5 Pumping Station 4 Break Pressure Tank 1

Take away

Water Safety Plan is a useful tool if it is implemented in right spirit

Acknowledgement

• Conference Organiser
• World Health Organisation
• Nagpur Municipal Corporation
• Orange City Water Private Limited
• Director, NEERI
• My colleagues - Aabha, Anisha, Priyanka, Viji and

Priya

• Dr Kapil Chandrayan

Thanks