Chongqing Urban–Rural Infrastructure Development Demonstration II Project (RRP PRC 45509)
Water Safety Plan
A. Background
1. Water Safety Plan
1. The Water Safety Plan (WSP) presents a new approach and shift in the way water supply systems are managed. In general, drinking-water suppliers usually ensure that the quality of water supplied to consumers meets specific national and regional standards. The World Health Organization (WHO) together with the International Water Association (IWA) recommend pro-active efforts to reduce risks and prevent contamination before water reaches the consumer. This can be achieved by shifting emphasis of drinking-water quality management to a holistic risk-based approach that covers the process of catchment-to-consumer. Embedded within the third and fourth edition of the WHO Drinking Water Quality Guidelines, the Water Safety Plan concept is the central element of the Framework for Drinking-water Safety which discusses the roles and responsibilities of different stakeholders.1 WSP is, therefore, considered the most effective means to ensure the consistent supply of safe drinking-water.
2. The WSP is a document created and for use of any organization that supplies water to others. It shows who from the organization will oversee the development and implementation of the WSP, as well as who is responsible for particular activities identified under the WSP. The WSP is regularly consulted as a key reference document as (i) the hazards, risks, and controls are reviewed systematically through operational monitoring; and (ii) management and communication systems are set up with consumers and external organizations who have influence on the water supply system and its source. The WHO and the IWA also produced a Water Safety Plan Manual, which illustrates the above functions of the WSP.2
3. Realizing the importance of the WSP concept, ADB has first prepared a guidance note to mainstream WSPs in ADB water projects in August 2011.3 The draft guidance note is being piloted in the processing of Chongqing Urban–Rural Infrastructure Development Demonstration II project.4 The project design has significantly benefitted from the application of WSP to identify potential environmental and socioeconomic risks associated with water safety, and enhance its engineering and non-engineering design to minimize potential risks. Meanwhile, the results of the pilot will be used to demonstrate how to mainstream a WSP into the ADB’s project cycle and to refine the guidance note for future use.
2. Proposed Project Scope
4. Project background. Wanzhou district in Chongqing Municipality is located 228 kilometers (km) away from the fast-developing western central region of Chongqing and is the largest urban center in the northeastern region. Wanzhou district administers 52 towns, townships, and neighborhood offices (with 12 townships, 29 towns, and 11 neighborhood offices), covering an area of 3,456 square kilometers, and its total registered population reached 1.75 million in 2011, of which the urban population accounted for 50%. Recently, Wanzhou’s economy has undergone rapid development. Its gross domestic product (GDP) increased from CNY7.3 billion in 2001 to CNY60.2 billion in 2011, where the secondary industry grew the
1 The WHO is promoting the WSPs through the latest edition of the Drinking Water Quality Guidelines (2008). 2 The manual is available at: http://www.who.int/water_sanitation_health/dwq/WSP/en/index.html. 3 ADB. 2011. Mainstreaming Water Safety Plans in ADB Water Projects :Guidance Note (Draft). Manila. 4 In December 2011, a pilot and demonstration activity of $50,000 from the Water Financing Partnership Fund was approved on Pilot Application of ADB Guidance Note for Mainstreaming Water Safety Plans in ADB Water Projects. 2 fastest by 90% from CNY3.5 billion to CNY35.0 billion compared with 74% and 88% for the primary industry and the tertiary industry, respectively.5
5. As of 2012, the total water supply capacity reached 206,500 cubic meters per day (m3/day). Although Wanzhou’s water supply system gradually developed along with its economic growth, the water sector confronts increasing challenges. Currently, Wanzhou has 11 existing municipal public water treatment plants built in various years, sizes, (2,000-100,000 m3/day) and locations. The plants were also owned and managed by different authorities. Four plants belong to the Wanzhou Water company limited, an enterprise directly under the Urban and Rural Construction Commission. The Water Resources Bureau and a subsidiary of Wanguang Group (private company) own and manage a total of seven plants. Overall water sector requires an urgent reform to enhance management efficiency and safety of water supply system by closing down obsolete plants, avoiding duplication of management, and upgrading the water quality management.
6. The proposed water supply subproject consists of: (i) provision of a new Yangliu water supply plant with capacity of 200,000 m3/day, (ii) construction of a new water intake and (iii) a new water distribution tunnel and the associated distribution network. The water intake, water transmission works (water transmission tunnel), and associated distribution pipelines will be financed by domestic counterpart funding, while the new Yangliu water supply plant will be financed by ADB. Based on the revised Chongqing Municipality Wanzhou Urban Master Plan (2010–2020) and Chongqing Municipality Wanzhou District Water Supply Strategic Plan (2010– 2020), the Wanzhou water supply system will be gradually merged and upgraded from 11 scattered small- and medium-sized plants to four centralized large-scale plants. The proposed Yangliu water supply plant will become the largest plant in Wanzhou and will play a significant role in medium- and long-term Wanzhou water reform, which will serve the drinking water of 0.73 million people in 2012 up to 1.5 million people in 2030.
B. Implementation of Water Safety Plan
1. Water Safety Plan Team
7. Project design stage. A preliminary WSP team was convened in April 2012. The persons involved in the WSP team are summarized in Table 1. The WSP team was formed mainly to pilot and incorporate the WSP into the project design. The team was primarily appointed to describe the system and proposed design and complete the preliminary risk assessment.
Table 1: Water Safety Plan Team at Project Design Phase Name Affiliation Position Role Wanzhou District Government (Supervising Government) Development and reform General coordinator of Zhang Zhongya Deputy Director commission (Wuzhou PMO) government stakeholders Wanzhou Water Co. Ltd. (Project Owner) Yan Jian General manager Implementation lead of the WSP
Xia Qingquan Chief Engineer Implementation lead of the WSP
5 PRC. 2002. Chongqing Statistical Year Book 2002. Chongqing; PRC. 2012. Chongqing Statistical Year Book 2012. Chongqing. 3
Table 1: Water Safety Plan Team at Project Design Phase Name Affiliation Position Role Production and Technique Local expert in production process Tan Jiaong Head Department and water quality Du Min Customer Service Center Director Local expert in customer relations Pipeline Development Tan Yuqiu Head Local expert in water reticulation Department Engineering Management Local expert in system Wei Wei Head Department engineering Yangtze River Inspectorate Plan and Design Institute (Local Engineering Design Institute) Water Supply Project Design Engineer responsible for overall Peng Wei Guang Head Department engineering design Project preparation consultant (Design Consultant) Dan Deere Water Futures Co.Ltd. Technical consultant WSP facilitator in public health WSP facilitator in water Lang Xiaowei IWA, China Technical consultant management Cheung Nai Chun AECOM, Asia Co. Ltd Technical consultant Project coordinator for consultants
Yan Wei AECOM Asia Co. Ltd Technical consultant Water engineer World Health Organization (Advisor) Environmental Health, Western Mien Ling Chong Technical officer Advisor Pacific Regional Office Asian Development Bank (Project Financier) Urban development Satoshi Ishii East Asia Department WSP proponent in ADB projects specialist Urban development Joanna Masic East Asia Department WSP proponent in ADB project specialist ADB = Asian Development Bank, Co = Company, IWA = International Water Association, Ltd = Limited, PMO = project management office, WSP = water safety plan. 1 Appendix Source: Asian Development Bank.
8. Project construction and operational stages. The construction period will be 2013– 2017. It is expected that different risks may become evident and relevant as the project progresses. This may require additional persons to be involved during construction and operational phases. In practice, most members of the WSP team are expected to remain
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involved. Based on the findings and capacity development training, both Wanzhou district government and Wanzhou Water Co. Ltd. realized the importance of the WSP team, which should continuously evolve from project design phase to project construction and operational phases. Under the project design phase, capacity building support will be provided to ensure a seamless transition of the WSP upgrading from design to construction and operational phases. It was agreed that the next stage for the WSP team should consider representatives from the Wanzhou district water resource bureau, health bureau and housing, urban and rural development bureau, upstream industrial area management office and upstream industries.
2. System Description
9. Proposed water supply and treatment system. The proposed water treatment system is in Table 2. The system flow diagram and network process flow diagram are in Figures 1 and 2, respectively.
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Table 2: Proposed Water Supply System Elements Description Source: Yangtze River Upstream: Chongqing, Zhongxian, Fuling, Changshou, mining, (pharmarthietical, mining, chemical, electronic, refining-metal) Note: Dam will be built upstream (Xiaolanhai dam project) Water catchment Water quality: Water quality testing report complies with surface water quality standards Grade II of GB3838-2002 for chemicals and Grade III for microbial tests. Monitoring frequency: All none conventional 31 items will be tested twice per year, and the conventional 9 items on a daily basis. Source: Yangtze River (14 km from treatment plant, 3.2 km upstream from the planned Yangliu stream wastewater discharge spot) Water Intake spot 3 Intake capacity: 350,000 m /d, Land area: 0.37 ha Phase I: Capacity of 200,000 m3/d Pumping stations 3 Phase II: Capacity of 150,000 m /d Pre-treatment System: Polyaluminumchloride dosing (if necessary), horizontal pre-sedimentation, secondary plant facility pumping station, solid discharge, and de-watering Water transfer Materials: Steel pipe. Phase I 200,000 m3/d for raw water transmission, via non-pressured mains gravity flow through closed channel Mechanical Flow type: Vertical flow mixture Coagulation and Agent: Polyaluminumchloride as a coagulant sedimentation Units: 16 units, total height 4.2 m, filtration area 67.6 m2, Filtration Filtration media: Sands, thickness of 1.2 m, dimension of 0.9-1.35 mm, K80 < 1.40 Back wash mode: Air flush, Air-water flush, Water flush Method: Chlorination Dose: 0.5-1.0 mg/l (designed water treatment capacity of 16,042 m3/h,) Disinfection Vacuum chlorine dosing machine, capacity of 8 kg/h each Dosing spots are located in the water inlet pipe of treated water storage. Chlorine leakage neutralizer Treated water 3 Numbers and size: Two tanks of 55 x 60 x 4.5 m storage Diameter and length: DN 1,000 with a length of 12.6 km (Jiangnan Water Treatment Plant–Chenjiaba) Main distribution DN 500 with a length of 10.3 km (Jiangnan Water Treatment Plan–Xintian Town) networks DN 500, with a length of 7.2 km (Jiangnan Water Treatment Plant–Changling Town) DN 500–1,000 with a total length of 13.2 km (to the existing pipe network in Baianba) Booster pump Number: 10 stations with the storage tank station Service reservoir Storage tanks Water supply Water meters (single stage, no dual style), backflow preventive valve installed when the users connections are using secondary water supply (approximately 60 users) Type: Overhead tank. Few cases that old resident community built them, most of the buildings Water use by are using none negative pressure water supply residents Break pressure tank for supply water to the roof tank ha = hectare, kg = kilogram, kg/h = kilogram per hour, km = kilometer, m = meter, mg/l = milligram per liter, mm = millimeter, m2 = meter, m3 = cubic meter, m3/d = cubic meter per day. Source: Asian Development Bank.
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Figure 1: System Flow Diagram
Appendix 1 Appendix
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Figure 2: Network Process Flow Diagram
10. Water quality standard. The applicable drinking water quality standard is GB5749-2006 (Standard for Drinking Water Quality). Some required monitoring parameters are not currently available. Upgraded water quality monitoring scheme including enhancement of the existing laboratory facility will be included under the project. It was noted that customarily, most people in Wanzhou do not drink water directly from the tap but and boil it before use.
3. System Risk Assessment
11. In April 2012, the WSP team conducted risk assessment by compiling a risk assessment worksheet (Table A-1: Appendix 1) and a process control and management matrix (Table A-2:
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Appendix 1). In general, WSP risk assessment documents are ongoing works and this design stage risk assessment matrix should be updated with a range of ideas and notes during construction and operational phases.
C. Opportunity for Improvement
12. A long-term expansion of the water supply system is planned for Wanzhou district. The current 11 small- and medium-sized water treatment plants will be gradually merged and replaced by 5 large centralized water supply plants. Moreover, under the Wanzhou water sector reform, the Wanzhou Water Co. Ltd will be the water operator for the whole water system in Wanzhou. Therefore, it is important that a WSP be owned and maintained by the Wanzhou Water Co. Ltd to permit its evolution in line with these operational changes. The current water quality standards are adequate given the current system condition in Wanzhou. A key part of a WSP for such a system is to set out step-wise improvements towards ensuring water safety and meeting those water quality standards more reliably. The WSP activity expects to identify the priority investments to be included in the project while others may need to be funded into the future. Advanced technology can form part of this solution, but can be introduced gradually by first adopting a conventional system, supported by some economical risk management measures in the short term. The WSP activity can also identify the capacity strengthening measures to be included in the project loan under 'training and capacity building'. As the WSP is a demonstration feature of the project, it is important to share the experiences gained from this process of system assessment, and WSP preparation and implementation with other water providers in Chongqing. Based on the system risk assessment, the following is a summary of improvement opportunities identified during the WSP process for further consideration during the construction and operational phases:
1. Catchment and Water Intake Point
(i) The catchment would be subject to possible unexpected spills from: (a) upstream industries’ illegal wastewater discharges, (b) accidental upstream domestic wastewater discharge, or (c) spills from the transport of hazardous substances in Yangtze river. As the likelihood for the occurrence is not that great, this kind of risk is not completely unavoidable. Yet, it is not practical to confidently prevent illegal discharges by industries themselves. In fact, a number of past spills were noted in Wanzhou. A review of the water quality data did not find hazardous chemicals above the standard values for water supply, and dilution is very significant. However, concerns were expressed by the Wanzhou Water Co. Ltd. about specific hazards, such as benzene, for which there was no treatment proposed. The proposed ‘conventional’ treatment would not necessarily and adequately mitigate all such foreseeable spill events. Both avoidance strategies and/or mitigation strategies should be considered.
(ii) Planned routine chemical and treated wastewater discharges that normally occur may result in source water pollution. After the completion of the Three Gorges Dam and with the increase water levels, there have been many polluted venues to be submerged below the water surface. Deterioration of water quantity due to the drought season will also result in poor dilution capacity. They would introduce microbial pathogens, such as Cryptosporidium, Giardia and E. coli, hazards into the source water. Agreed upstream wastewater discharges, therefore, must be strictly monitored to ensure the effluent quality is within acceptable standard levels, to avoid high load impact to the source water. 7
(iii) The water intake point will be located in the left bank of the mainstream of the Yangtze river, upstream of the Dishui stream. The spot condition of water intake is ideal. Although this spot experiences seasonal sediment accumulation and erosion, the spot is basically balance within a year, with little impact to the water intake condition. The water intake spot is also 297.3 km upstream away from the Three Gorges Dam, located at the end of the sedimentation area of the Yangtze river, it is still within the backwater area. At present, the source water quality basically meets Surface Water Environmental Quality Standard (GB3838-2002) value of its Grade II water body standard, and Water Quality Standard for Drinking Water Source (CJ3020-93) of its Grade II standard. However, medium- and long-term change of the water quality should be carefully analyzed as fecal coliform often exceeds the standard. The upstream domestic wastewater discharge is considered as the source of fecal coliform.
(iv) Rain events cause excessive turbidity that overwhelms the treatment plant and causes excessive siltation of the pipelines. Overwhelming the treatment plant could lead to pathogen breakout if the treatment processes cannot react to the high turbidity load, this will result in the filtration overload, and will lead to filtration failure.
(v) Some of the substances listed in the drinking water standards had not been regularly tested. Although contaminated problems were not evidenced by the available data, a more extensive testing program might find some problematic substances in future.
2. Pre-treatment Plant
(i) Algal blooms in the sedimentation basin may lead to algal toxins pollution 1 Appendix accident, and taste/odor compounds (e.g., cyanotoxins, geosmin, methyl- isoborneol) exceed the standard requirement. Currently the possibility of algal blooms in the Yangtze River as the source water, is little but with the passage of time and once the situation changes, there may be a need to extend the raw water’s residence time in the sedimentation basin. In this case, there is a need to prevent the risk of algal blooms, especially during the summer time.
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(ii) Based on the design, the water production volume would be 200,000 m3/day. In full scale production and operation, 9,166.7 cubic meter per hour (m3/h) with two basins of dimension 52.2 x 32.8 x 5.8 m (9,930.5 m3) would only have approximately a 2-hour residence time at most and would normally run at a higher flow rate. Under this condition, the pre-treatment effluent effectiveness becomes very important to the system safety especially during the poor raw water quality period, and special attention has to be paid to this issue.
3. Water Transfer Channel
(i) The risk of the pre-treated water transfer channel may be the sand sedimentation to cause blockage of the channel. The blockage will result in the reduction of water to transfer.
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4. Coagulation, Flocculation, and Filtration
(i) The mechanical failure of chemical dosing system results in the failure of the coagulation, flocculation, and sedimentation processes. The excessiveness of the treated water effluent results to excessive turbidity, and indirectly the bacteria. The control measure may be necessary to backup the chemical dosing system, and meanwhile to install automatic dosing pump with integrated alarm system in the event of operational failure/error.
(ii) Inadequate quality and use of chemicals will result in various possible contaminants introduced into the water. In the operational practice, random sample testing system is in place for coagulant chemical, and coagulant must meet the national product standard GB1892-2009 and GB/T17278. Coagulant can only be purchased from approved suppliers.
(iii) Failure in the filtration system will cause turbidity value to exceed the operational standard requirement, indirectly, the pathogens. Post filtration turbidity monitoring on line and continuous is encouraged, and this monitoring operational result will go to an alarm leading to operator response to adverse results. Multiple separate filtration units in parallel will provide mutual backup. A filtration system maintenance program should be developed and implemented.
5. Chlorination Disinfection
(i) Inadequate chlorine dosing or disinfection failure due to chlorination system failure or error will result in increasing the risk of pathogens. On the other hand, chlorine overdose will result in chlorinous taste and odor, and disinfection by- products produced. The control measure is to automate chlorine dosing equipment and to adopt on line continuous monitoring, to achieve a maximum treated water free chlorine residual concentration after 30 min of: target 0.8 mg/l, critical limit ≤ 1 mg/l, meanwhile to backup chlorine dosing machine. The target and maximum critical limit values for chlorine dose meet the national standards requirement: ≤4 mg/l.
6. Water Storage, Service Reservoir, and Pump Stations
(i) Birds and animals (e.g. frogs, lizards, rodents), worms may defecate in water tank, their activities can cause pathogen contamination through fecal waste occasionally discharged into the storage tank. The designed control measures include: (i) tank is roofed, (ii) vents and overflows are meshed, and (iii) chlorine is dosed to the treated water and is carried through as a residual.
(ii) Malicious contamination (e.g., terrorism, sabotage) events can result in various possible contaminants, especially poisonous matters, to pollute the treated water. This will lead to a stop in the supply water and even a shut-off of the whole/a part of the water supply system. The sites for treated water storages and pumping stations will need to be fenced and secured with closed circuit television monitoring with video images.
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(iii) Groundwater can enter into treated water storage due to underground storage tank leakage. Such groundwater may bring contaminants from the soil to the storage tank and will result in various possible contaminants to pollute the water. The suggested control measure would be for the storage tank walls to be lined with a water proof lining that is maintained and inspected periodically.
(iv) The power and/or technical failure in pumping station facility, will result in the contamination of water in the water supply system by the loss of pressure, which leads to contaminant entry due to back-siphonage. Control measures should be considered for: (a) backup pumping station facility, (b) rapid response to power failure, and (c) have dual power supply feeds by design. If it is difficult to meet dual supply power feeds, a single circuit power supply should be considered.
7. Distribution Mains and Network
(i) Pipe burst of the distribution main in polluted areas will result in various possible contaminants to enter the network due to pressure loss. The control measures can be to: (a) use robust pipe materials (e.g., steel pipe, ductile iron pipe, cast iron pipe), (b) adjust system operational procedures, (c) strictly follow the procedures for operating the system to avoid pressure spikes and water hammer, and (d) enforce procedure for operation and maintenance.
(ii) The Wanzhou Water Co. Ltd. is not responsible for the contamination after the water meter. It is important for the WSP team to fully realize the importance of water quality management after the water meter, and to consider the management of water by the community and by individual consumers, such as within office, commercial, and public buildings (e.g.,hospitals, schools).
(iii) Risks associated with the existing pipelines and other water related facilities must 1 Appendix also be realized as potentially significant and in need of further investigation. For instance, risks associated with poor management of backflow prevention and treated water storage at the point of use, were noted to be potentially significant.
8. Consumer Connections
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(i) The consumer connections to the distribution network can have potential accident factor. For instance, the backflow of contamination into the network from hazardous facility connections, such as hospital or industrial users. This can bring various possible hazards into the network and pollute the water. Installation of backflow prevention devices for hazardous customer connections may be encouraged to maintain certain level of network pressure to avoid short time pressure loss accident. The inherent control can be to make water flow into the customer property at a rate faster than diffusion of hazard out of the building.
(ii) Consumer roof tanks can be contaminated by animals or sabotage, which will result to contamination prior to entry of clean water. Routine maintenance and tank cleaning should be planned and implemented for periodic disinfection. Those tanks should be in locked room to set up the closed sealed tank room.
(iii) Consumer underground tanks can also be contaminated through the entry of groundwater to clean water tank, the misconnection of the different pipes, and
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close proximity of the clean water tanks and septic tanks within the community. These kinds of accidents can bring various possible hazards into water. The control measures to these accidents can be to: (a) designate a person in-charge from within the property management, (b) keep tank in confined, locked area, to set up a closed sealed tank room, (c) keep the tank waterproof lined, and (d) keep tank away from potential pollution sources. Even with all control measures in place, this should be highlighted, as risks still remain.
(iv) When the consumer installs in-door pipes, the use of inappropriate materials in contact with water can introduce various possible hazards into the water. For instance often galvanized iron causes dirty water or lead from inappropriate solder. In practice, the related operational procedures and standards are in place, but poorly enforced.
9. General Issues and Laboratory Facilities
(i) The use of contaminated materials in contact with water can introduce various possible hazards into treated water. All the parts materials used in the water supply system must comply with the standard of GB/T 17219-1998.
(ii) The existing laboratory facility and monitoring mechanism should be strengthened to fulfill the necessary routine testing and frequency. The CJ/T206- 2005 Urban Water Supply Quality Standard requires urban public and centralized water supplier and self-constructed water supply units to supply drinking and other purpose water to the urban residents. It lists the water quality testing items and the testing frequency. This standard is the guidance for the urban water suppliers to accomplish their testing work.
D. Conclusion
13. The WSP at the project design phase has been completed. As the WSP itself being an evolving plan, it should be further deepened and improved based on the constructed water supply system and surrounding socioeconomic environment during the construction and operational phases. Among other risks identified by the WSP, the assessment highlighted the necessity of locally tailored WSP to ensure sustainable drinking water quality management. In Wanzhou district, for example, it is customary for drinking water to be boiled, or used as part of boiled drinks such as tea, or bottled water. Therefore, the volumes of unboiled water consumed by the general public would be relatively small. Although this finding does not affect the assessment of risks related to most chemicals (being unaffected by boiling), microbial risks are adequately mitigated by boiling. The WSP at the project design stage suggests that the upgrade of WSP in the next phases needs to be holistic, even taking such local custom into account to draw most effective WSP activities and risk mitigation measures.
14. Along with the expected increase of the drinking water quality standard in the PRC, more pressure will be on the Wanzhou Water Co. Ltd., who will be the main water supply operator in Wanzhou. As a result of their water sector reform, roles and responsibilities of Wanzhou Water Co. Ltd. are expected to be significantly expanded. Their service should cover: (i) supplying stable quantity of water to growing number of industrial customers and additional 1.5 million people in 2030; (ii) assuring continuous water quality and safety for 24-hours/365 days; (iii) managing one of the largest urban utility infrastructures in Wanzhou; (iv) monitoring various parameters and indicators, and disclosing to public; (v) handling operation and maintenance of 11 infrastructures; (vi) maintaining financial viability of the water sector; and (vii) continuously improving its service quality.
15. Although this was the first application of the draft ADB–WHO WSP guidance note to actual loan assistance in the PRC, the WSP activity at the project design stage successfully identified the potential risks which should be addressed to ensure a long-term safety of drinking water supply in Wanzhou. Based on the findings, the project investment component will include procurement of comprehensive laboratory equipments to enable the Wanzhou Water Co. Ltd. to fulfill the required water quality monitoring. The project implementing consulting service will include a total of 6 person-months of international and national water sector specialists, who upgrade the WSP and provide comprehensive capacity building on the water sector reform.
Appendix 1 Appendix
11
12 Appendix 1
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- Low Low Risk post rating control
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Hazard Chemical contaminant various possible Chemical contaminant various possible
ned
event Hazardous wastewater wastewater dischargesthat exceeds the permitted levelsof discharging quality Unplanned Unplan spillchemical event
Processstep Yangtze River Yangtze source water Yangtze River Yangtze source water
Risk Control measures in Risk rating place and proposed to rating Actions required
Hazardous with no manage significant post- (investigation or
Severity Severity
Likelihood Likelihood Riskscore Process step event Hazard Riskscore control risks control Notes improved controls) Yangtze River Planned Chemical 5 1 5 Low Dilution in the river 5 1 5 Low The water quality source water routine contaminant - would be significant and data reviewed to chemical various provides an inherent date did not find discharges that possible control. Agreed hazardous normally occur wastewater discharges chemicals above must be within guideline values for acceptable levels water supply
Yangtze River Faecal waste Microbial 5 5 25 Very Dilution in the river 5 1 5 Low Validation of control source water matter entering pathogens high would be significant and measures the water such as provides an inherent necessary. source Cryptosporidiu control. Agreed Chlorination meets m, Giardia and wastewater discharges national standards? E. coli. must be within Filtration meets what acceptable levels. standard? This risk Coagulation-filtration is specifically Chlorination controlled by the treatment plant Yangtze River Rain causes Turbidity 4 4 16 Very 4 1 4 Low source water excessive (indirectly: high turbidity and pathogens) siltation of the pipelines. This could lead the filtration plant to pathogen breakthrough. Pre- Algal blooms in Algal toxins 1 4 4 Low Inherently controlled by 0 N/A sedimentation the and taste/odor turnover in the basin. basin sedimentation compounds Production volume of 1 Appendix basin (Cyanotoxins 200,000 m3/day (9,167 Geosmin m3/h) with 2 basins of Methyl- dimension 9930.1 m3 isoborneol) would approximately have a 2 hour residence time at most. A higher flow rate is needed to
give approximately 30 13
mins residence time.
14 Appendix 1
(investigation or Actions requiredActions improved controls)
having having
Notes Controls modulate and bothlikelihood severity, e.g. multiple filtration banks parallel in reducesseverity.
- Low Low Low Low
Risk post
rating control
Risk score Risk
4 4 3 1
Severity 4 4 3 1
Likelihood 1 1 1 1
2009. 2009. pump
- e and
lin - must meet risks
manage significant manage significant Control measures inControl measures place and proposed toplace and proposed maintenance program. velocity of water invelocity water the of pipe Backup coagulant system.dosing Automatic dosing integratedalarmwith eventsystem theof in failure Random sample testing systemplace in is for coagulant chemical. Coagulant theproduct national standard GB1892 can Coagulantonly be purchased from approvedsupplier Post turbidity filtration monitoring on continuous goes which toalarm to an leading tooperator response adverse results. Multiple separate infiltration units parallel providing mutual backup.Filtration This risk inherently is controlled the by
w Lo high Very Very Risk
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Risk score Risk
8 8 1 15
Severity 4 4 5 1
Likelihood 2 2 3 1
-
Hazard Chemical contaminant various possible Turbidity (indirectly: pathogens) No water Turbidity (indirectly: pathogens)
event Hazardous Failure of filtration system contaminated coagulant failure of chemical system dosing Use of Sedimentation causing blockage the of channel Mechanical
Processstep Filtration Coagulation + flocculation Coagulation + flocculation Raw Raw water transfer channel
Risk Control measures in Risk rating place and proposed to rating Actions required
Hazardous with no manage significant post- (investigation or
Severity Severity
Likelihood Likelihood Riskscore Process step event Hazard Riskscore control risks control Notes improved controls) Chlorination Inadequate Pathogens 2 5 10 High Automated dosing and 1 5 5 Low Validation of control chlorine dosing on line continuous measures: The due to monitoring to achieve a target and minimum chlorination minimum treated water critical limit values system failure free chlorine residual for chlorine dose concentration after 30 exceed the national min of: target 0.8 mg/L, standards critical limit ≥ 0.5 mg/L. requirement: ≥ 0.3 There is a duty and mg/L after 30 mins standby chlorine dosing for primary dose and system. residual disinfectant concentration of ≥ 0.05 mg/L at the tap. Chlorination Over dosing of Chlorinous 2 3 6 Medium Automated dosing and 1 3 3 Low Validation of control chlorine taste and odor on line continuous measures: The and monitoring to achieve a target and maximum disinfection by- maximum treated water critical limit values products free chlorine residual for chlorine dose concentration after 30 meet the national min of: target 0.8 mg/L, standards critical limit ≤ 1 mg/L. requirement: ≤ 4 mg/L. Treated water Birds and Pathogens 2 5 10 High Tank is roofed. 1 5 5 Low storage animals Vents and overflows are defecating in meshed. water tank and Chlorine is dosed at the causing treatment plant and contamination carries through as a residual. Treated water Malicious Contaminants - 2 5 10 High The site is fenced and 1 5 5 Low 1 Appendix storage contamination various secured with closed (terrorism, possible circuit television sabotage) monitoring with video images retained for one week. Treated water Groundwater Contaminants - 2 5 10 High The storage walls are 1 5 5 Low storage ingress into various lined with a water proof
treated water possible lining that is maintained 15
storage and inspected
16 Appendix 1
(investigation or Actions requiredActions improved controls)
Notes
- Low Low Low Low Low
Risk post
rating control
Risk score Risk
5 4 5 5 5
Severity 5 4 5 5 5
Likelihood 1 1 1 1 1
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ion ion for cleanly cleanly for
risks
esign. manage significant manage significant Control measures inControl measures place and proposed toplace and proposed padlocked shut. padlocked storageareThe walls lined a proo with water maintainedlining that is and inspected power failurepower have and supply feedsdualpower d by steelUse pipe of robust Procedures for systemoperatingthe to spikes avoid pressure and hammer water Procedure to damage any repairing theincluding pipe cleaned flushing of the pipe Tank is roofed. Vents areoverflows and meshed. Chlorine at dosed is the treatmentplant and carries a as through residual. siteThe fenced.is Somesites closed have circuit televis monitoring video with forimages one retained week. Roof hatches are Backup pumping station Backupstation pumping and to rapid response
High High High High Risk
rating
control with no Medium
Risk score Risk
8 10 10 10 10
Severity 5 4 5 5 5
Likelihood 2 2 2 2 2
- -
-
- Hazard Contaminants various possible Contaminants various possible various possible Pathogens Loss of pressure leading to contaminant entry dueto back siphonage Chemical contaminant
event Hazardous treated water treated water storage sabotage) Groundwater ingressinto causing contamination Malicious contamination (terrorism, Birdsand animals defecating in tankwater and Pipeof burst the distribution main in pollutedarea Pumping station facility failure, power failure
Processstep Service reservoir reservoir Service Service reservoir Distribution main Pumping station
Risk Control measures in Risk rating place and proposed to rating Actions required
Hazardous with no manage significant post- (investigation or
Severity Severity
Likelihood Likelihood Riskscore Process step event Hazard Riskscore control risks control Notes improved controls) Booster Pumping Loss of 2 5 10 High Backup pumping station 1 5 5 Low pumping station facility pressure and rapid response to station failure, power leading to power failure and have failure contaminant dual power supply feeds entry due to by design. back- siphonage
Distribution Pipe burst of Chemical 2 4 8 Medium Procedures for 1 4 4 Low network the distribution contaminant - operating the system to main in various avoid pressure spikes polluted area possible and water hammer. Procedure for cleanly repairing any damage to the pipe including flushing of the cleaned pipe All parts Use of Various 2 4 8 Medium All materials used must 1 4 4 Low contaminated possible comply with GB/T materials in hazards 17219 contact with water
All processes Use of Various 2 4 8 Medium All materials used must 1 4 4 Low contaminated possible comply with GB/T chemicals hazards 17218 added to drinking water supply
Appendix 1 Appendix Customer Backflow of Various 4 5 20 Very Backflow prevention 2 5 10 High Recommend more connections contamination possible high devices in place for reliable backflow to distribution into the hazards hazardous customer prevention be installed network network from connections. Maintain at high hazard sites
hazardous network pressure. facility such as Inherent control: water hospital or flow into the customer
industry property at a rate faster 17
than hazard diffusion out of the building
18 Appendix 1
(investigation or Actions requiredActions improved controls) Recommend enhanced plumbingcompliance to regulations.For new properties is there inspectionin place, but not older buildings. for Recommend more reliableprotection be required for underground tanks
-
is th
- Notes The water company water The oftenexperiences dirtycomplaints of that towater out turn be sub caused by standardcustomer plumbing control poorly is managedin practice. These are tanks required allow to buildings provide to sufficient water during peak demand periods fire for and cannotflows andso bereadily removed from process. the
- Low High Risk post rating
control Medium
.
Risk score Risk
8 5 10
Severity 5 4 5
Likelihood 2 2 1
.
Closed
.
tial pollution
. risks
. Closed sealed Closed Keep tank away tankKeep away . . permilligram litermg/L = hour, per nese plumbing nese plumbing manage significant manage significant nforcement the of Control measures inControl measures place and proposed toplace and proposed Designated person inDesignated person thecharge from within managementproperty Keepin locked tank room tank room inDesignated person thecharge from within management. property confined, Keepin tank lockedarea room sealed tank Waterproofthe of lining tank from poten sources must All used materials thecomply with Chi regulations. E regulation necessary as currently the regulation is enforced. poorly Cleaning procedure Periodic disinfection
high high Very Very High Very Very Risk rating control with no
/h = cubic metercubic /h =
3
Risk score Risk
20 12 20
Severity 5 4 5
Likelihood 4 3 4
Hazard lead from inappropriate solder possible hazards Various hazards (e.g. galvanized iron for instance) which causes ordirty water Various possible hazards Various
/day = cubic meter per day, m day, metercubic per /day =
3
ge
event ress into ress Hazardous materials in contact with water Use of inappropriate Groundwater ing treated water storage Contamination of roofthe tanks through animals or sabota
/day = square meter per day, m day, meter persquare /day = 2 Processstep plumbing Customer Customer underground tanks Customer roof tanks m Source: AsianBank. Development
Table A-2 Process Control and Management Matrix Validation of Process Control Hazards Monitoring Target Critical control Follow up step measure controlled parameter criteria limit Monitoring Corrective action measure actions Yangtze Use of Various Event- Event- Event- Where: Event- Event-specific. Can river source alternative possible specific specific specific specific switch to JiangBei source contaminants When: Event- (north of river) in short- from unusual specific term or JiangNan (south events Who: Local of river) in long-term government and water treatment plants EPB are first as these draw from the responders. reservoir rather than the Wanzhou Water Co. river source. and CDC review and act on results. How: Event-specific Pre- Solids Turbidity Turbidity Turbidity Turbidity Where: Urgently review and This is the Should the sedimentati removal by Some metals target is must be The sample is drawn improve pre- practical limit of plant achieve on, these Some color < 0.5 ≤ 0.8 from the outlet of the sedimentation and achievability of best practice coagulation, process Some organics NTU NTU combined filter solids removal the plant and for protozoa sedimentati steps Micro- effluent pond processes to reduce will allow 1 NTU (Cryptosporidi on and organisms When: Continuously turbidity. Actions may to be achieved um and filtration from the Who: Control centre include increase at the point of Giardia) source water, of the Wanzhou backwashing frequency, supply as per control which such as Water Co. modifying coagulant the GB5749- has lower bacteria (inc. How: Turbidity dosing rate or choice of 2006 standard. turbidity E. coli), viruses analyzer coagulant and repairing targets of and protozoa or replacing filter media 0.15 NTU? (Cryptosporidiu and system m and Giardia) components. Advise CDC and keep them informed of the situation. Pre- Solids Turbidity Turbidity Turbidity Where: At sample Review and improve Based on Note that sedimentati removal by must be taps within the pre-sedimentation and meeting Table 1 CDC 1 Appendix on, these ≤ 1 NTU network solids removal of GB5479- undertakes coagulation, process When: Weekly processes to reduce 2006 for the monthly sedimentati steps Who: Wanzhou turbidity. requirement to verification on and Water Co. Review need for be achieved: ≤ sampling at
filtration How: Testing in the storage and network 1 NTU taps laboratory cleaning/flushing or component replacement. 19
20 Appendix 1 o
ions that that
. tact time tact time act Follow up Note CDC undertakes monthly verification sampling at taps Ensure sufficient con underall conditionst meet30the minute contact time requirement of the standard.
- - -
the the
for the the for
control measure Validation of of GB5479 2006 for requirement to be < achieved: 4 mg/L Basedon meeting 2 Table of GB5479 2006 the for requirement to be ≥ achieved: 0.05mg/L Basedon meeting 2 Table of GB5479 2006 requirement to be ≥ achieved: 0.3after mg/L 30 minutes contact time. Refer to evidence of sufficient contact time. Basedon meeting 2 Table
ter that NTU = Nephelometric Turbidity Units = NephelometricNTU Turbidity age
age Corrective actionCorrective provide required the chlorine atdose, dose downstream booster stations where available. areFor areas that serviced wa by hasnot been meet thedisinfected to standard, the advise tohealth department public issueofallow a warning. Reduce chlorine the dos Increase primary chlorinedos Increase the chlorineIncrease the dose if possible. If primary chlorination system to unable is
e
mg/l = milligram per liter, permilligram mg/l =
The sampleThe At sample The sampleThe
Continuously Continuously Weekly
Controlcentr Controlcentre Wanzhou Chlorine Chlorine Testing in
Monitoring laboratory When: Who: Wanzhouof the Water Co. How: analyzer Where: fromis the drawn outlet the pipe of tank.treated water When: Who: Wanzhouof the Water Co. How: analyzer Where: taps the within network When: Who: Water Co. How: Where: fromis the drawn outlet the pipe of tank.treated water
- - -
limit Critical mg/L ration must be ≥ 0.3 mg/L Free residual chlorine concent ration must be ≤ 4 mg/L Free residual chlorine concent ration must be ≥ 0.05 Free residual chlorine concent
- -
et Target criteria ration target value is 0.81 to mg/L. The design targetis for ≥ 0.5 mg/Lat all times Free residual chlorine concent ration targ value is 0.81 to mg/L. Free residual chlorine concent
; EPB = Protection Environment Bureau; ; EPB
Free residual chlorine Free residual chlorine Free residual chlorine parameter Monitoring -
E. E.
- - s and and s - -
r and r and
Hazards controlled ganisms that ganisms r r products Chlorine sensitive micro o might the enter distribution system, such as bacteria, viruse coli Directly: chlorine (excessive chlorinemay cause taste, odo discomfort). Indirectly: disinfection by Chlorine sensitive micro o from the source water, such as bacteria, viruses and coli
- - -
Control measure sufficient to meetthe national standard GB5479 2006 GB5479 2006 Provide chlorine residual Avoid overdosing above the national standard GB5479 2006 Provide primary dose of chlorine sufficient to meetthe national standard Center for Disease Control and Disease Control Prevention for Center
CDC = CDC step
Process (and distribution) Chlorination Chlorination (and distribution) system Chlorine dosing Source: AsianBank. Development Note: