L11 Water Safety Plan (WSP) PDF

EOH 4104 WATER QUALITY IN ENVIRONMENTAL HEALTH LECTURE 11 WATER SAFETY PLAN (WSP) DR. SHAHARUDDIN MOHD SHAM Department of Environmental and Occupational Health, FPSK UPM  CONTENT OF LECTURE 1. Introduction 2. Organising the development of WSPs 3. Water supply description...

EOH 4104 WATER QUALITY IN ENVIRONMENTAL HEALTH LECTURE 11 WATER SAFETY PLAN (WSP) DR. SHAHARUDDIN MOHD SHAM Department of Environmental and Occupational Health, FPSK UPM  CONTENT OF LECTURE 1. Introduction 2. Organising the development of WSPs 3. Water supply description 4. Understanding the hazards and threats 5. Control measures and priorities 6. Limits and monitoring 7. Management procedures 8. Supporting programmes 9. Documentation and record keeping 10. Validation and verification  1. INTRODUCTION Water supply systems can be considered as a number of steps aimed at assuring the safety of drinking- water, including: preventing pollution of source waters; selective water harvesting; controlled storage; treatment prior to distribution; protection during distribution; and safe storage within the home and, in some circumstances, treatment at the point of use. These steps can function as barriers, where activities are designed to minimise the likelihood of contaminants entering the water supply or reduce or eliminate contaminants already present in the supply. With the multiple barrier approach, each barrier provides an incremental reduction in the risk of water becoming unsafe. If there is a failure at one point, the other barriers continue to provide protection.  * soalan wsp. air - Jaga punces dir - Tany Qualifi It is important that risk management is inclusive and, therefore, needs to cover the whole system from catchment to consumer FRAMEWORK FOR SAFE DRINKING-WATER AND WATER SAFETY PLANS The Guidelines for Drinking-water Quality WHO (2004) outlines a Cpreventive management frameworkCfor safe drinking-water that comprises five components, three of which combine to form the water safety plan. C Framework for safe drinking-water 1.CHealth-based targets 3 Health-based targets provide the basis for the application - of the Guidelines to all types of water supply. The purpose of setting targets is to mark out milestones to guide and chart progress towards a predetermined health and/or water quality goal. They are an integral part of health policy development. Define health-based targets. CE (i) --- goals cross contamination. 1) quality 2. Water safety plan The objectives of a water safety plan are - to ensure safe drinking-water through - good water supply practice, that is: - Cto prevent contamination of source( waters; (to treat the water to reduce or remove contamination( that could be present to the extent necessary to meet the water - - - quality targets; and - Cto prevent re-contamination during storage, distribution and handling of - - drinking-water. - 3. Surveillance The third main element of the framework for safe drinking- water is surveillance. Surveillance contributes to the protection of - public health by promoting improvement of - - the quality, quantity, access, affordability, - and continuity of water supplies and is -- complementary to the quality control - function of the drinking-water supply - - - agency. -  2. ORGANISING THE DEVELOPMENT OF WATER SAFETY PLANS DEVELOPMENT OF A WATER SAFETY PLAN A Cwater safety plan C essentially consists of three components; system assessment; - operational monitoring; and - management plans, documentation - and communication. - -  - Steps in the development of a - water safety plan - ASSEMBLE THE WATER SAFETY PLAN TEAM The preliminary - step is to assemble - a team to develop the water safety plan. For large supplies, a multi-disciplinary team of key people should be assembled to develop the plan. This should include managers, engineers (operations, maintenance, design, capital investment), water quality controllers (microbiologists and chemists) and technical staff involved in day-to-day operations. All members of the team should have a good knowledge of the system. Other desirable features of the water safety plan team include: knowledge of the water supply system and the types of drinking-water safety hazards to be anticipated; authority to implement any necessary changes to ensure that safe water is produced; inclusion of people who are directly involved with the daily operations; and having sufficient people on the team to allow for a multi- disciplinary approach, but not so many that the team has difficulty in making decisions. Team numbers will vary according to the size of the organisation and complexity of process. The use of sub- teams is common and might for example include, water harvesting, water treatment and distribution operations. INTENDED WATER USE For general purposes, water safety plans will apply to domestic potable use of drinking-water. The expected use of the product should, however, be determined and documented by the water safety plan team. Factors that need to be considered include: what consumer education is in place for water use and how is this communicated, including how consumers are notified of potential contamination? who is the water intended for and what is its intended use? what special considerations are in place for vulnerable groups such as infants, hospitalised patients, dialysis patients, the elderly and immuno-compromised? Are there any groups for whom the water is specifically not intended? the numbers of people served by different service levels (communal, yard, within-house – see Tables 3.2 and 3.3); and socio-economic status of different communities served.  3. WATER SUPPLY DESCRIPTION DESCRIBE THE WATER SUPPLY The first step in the system assessment process is to fully describe the water supply. Catchments Geology and hydrology Meteorology and weather patterns General catchment and river health Wildlife Competing water uses Nature and intensity of development and land-use Other activities in the catchment which potentially release contaminants into source water Planned future activities Surface water Description of water body type (e.g. river, reservoir, dam) Physical characteristics such as size, depth, thermal stratification, altitude Flow and reliability of source water Retention times Water constituents (physical, chemical, microbial): Protection (e.g. enclosures, access) Recreational and other human activity Bulk water transport Groundwater systems Confined or unconfined aquifer Aquifer hydrogeology Flow rate and direction Dilution characteristics Recharge area Well-head protection Depth of casing Bulk water transport Treatment systems Treatment processes (including optional processes) Equipment design Monitoring equipment and automation Water treatment chemicals used Treatment efficiencies Disinfection removals of pathogens Disinfection residual / contact period time Service reservoirs and distribution systems Reservoir design Retention times Seasonal variations Protection (e.g. covers, enclosures, access) Distribution system design Hydraulic conditions (e.g. water age, pressures, flows) Backflow protection Disinfectant residuals  Generic system flow diagram 4. UNDERSTANDING THE HAZARDS AND THREATS HAZARD IDENTIFICATION Hazards may occur or be introduced throughout the water system, from catchment to consumer. Effective risk management, therefore, requires identification of all potential hazards, their sources, possible hazardous events and an assessment of the risk presented by each. The hazard identification step, therefore, requires the water safety plan team to consider all potential biological, physical, chemical and radiological hazards that could be associated with the water supply. The team should start with the water sources, then progress through the validated flow diagram. At each step the objective is to: identify what could happen to lead to contamination; and the associated control measures for each hazard. The water safety plan team should also consider influencing factors such as: variations due to weather; accidental or deliberate contamination; pollution source control practices; wastewater treatment processes; drinking-water treatment processes; receiving and storage practices; sanitation and hygiene; distribution maintenance and protection practices; and intended consumer use Biological hazards These hazards include frank and opportunistic pathogens such as: bacteria; viruses; protozoa; and helminths Other, non-pathogenic organisms that influence the acceptability of drinking-water should also be considered. These include Asellus and Cyclops. It is not necessary or practical to completely eliminate microorganisms from drinking-water supply systems. What is required is to keep numbers of pathogens below levels determined to represent an acceptable level of risk as outlined in the water quality targets. Pathogens in water supply systems generally originate from human or animal faecal material contaminating raw water or that finds its way into the water supply delivery system. common sources of faeces include wildlife such as birds, grazing animals and vermin in and around reservoirs, backflow from unprotected connections and sewer cross connections Chemical hazards A chemical hazard can be considered as any chemical agent that may compromise water safety or suitability. Physical hazards Physical hazards may affect water safety by posing a direct risk to health (e.g. through choking), through reducing the effectiveness of treatment and in particular residual disinfectants or because consumers find the water unacceptable and use alternative, more contaminated water sources. The most common physical hazard in water is sediment within the water supply. Sediments and particulates can also include pipe materials, pipe liner materials, sloughed biofilms or iron and manganese films. Suspended or resuspended sediments can contain toxic chemicals or can have pathogens attached and can co- transport other hazards. Radiological hazards Radiological contamination of drinking-water generally occurs as a result of contamination by man-made sources of radiation. Contamination can arise from: naturally occurring radioactive species in drinking-water sources; the contamination of water from the mining industry; and radionuclides from the medical or industrial use of radioactive materials. HAZARDOUS EVENTS Once hazards are listed it is important to consider the corresponding events that lead to their entry into the drinking-water supply. These might be termed hazardous events or hazard causes. Hazardous events can cause contamination directly and indirectly. For example, pathogens can enter water supplies directly from faeces. However, cyanobacterial toxins result from growth of toxigenic cyanobacteria which are in turn promoted by a combination of factors. Therefore, factors, such as nutrients, which can promote cyanobacterial proliferation, can lead to water becoming unsafe and should be considered as contributory factors leading to the presence of a hazard. These contributory factors require managing as part of the water safety plan. Prioritisation matrix By using a semi-quantitative risk assessment, the water safety plan team can calculate a priority score, for each identified hazard. The objective of the prioritisation matrix is to rank hazardous events to provide a focus on the most significant hazards. The risk posed by individual hazards does not need to be quantified. There are a number of approaches to ranking risk. The water safety plan team needs to determine which approach it will use. The likelihood and severity can be derived from the water safety plan team’s technical knowledge and expertise, historical data and relevant guidelines.  5. CONTROL MEASURES AND PRIORITIES DETERMINE CONTROL MEASURES In many instances control measures (often referred to as ‘barriers’) will already be in place, where this is the case they should be assessed to determine if they meet current (i.e. health-based target) requirements. Control measures are identified by considering the hazardous events that can cause contamination of water, both directly and indirectly, and the activities that can mitigate the risks from those events. Control measures need to be identified at the point of contamination (where the hazardous event occurs) as well as downstream so that the effect of multiple barriers can be assessed together. Control measures can be effective in reducing the levels of hazards in a number of ways: reducing their entry into the water supply, reducing their concentration once in the supply; or reducing their proliferation. 1. Resource and source protection Effective catchment management has many benefits. By decreasing contamination of source water, the amount of treatment and quantity of chemicals needed is reduced. This may reduce the production of treatment by-products and minimise operational costs. Effective resource and source protection include the following elements: developing and implementing a catchment management plan, which includes control measures to protect surface and groundwater sources; ensuring that planning regulations include protection of water resources (land use planning and water shed management) from potentially polluting activities and are enforced; and promoting awareness in the community of the impact of human activities on water quality. Examples of source water, storage and extraction control measures Source water and catchments Designated and limited uses Registration of chemicals used in catchments Specific protective requirements (e.g. containment) for chemical industry or refuelling stations Reservoir mixing/destratification to reduce growths of cyanobacteria, anoxic hypolimnion and solubilisation of sedimentary manganese and iron pH adjustment of reservoir water Control of human activities within catchment boundaries Control of wastewater effluents Land use planning procedures, use of planning and environmental regulations to regulate potential water polluting developments Regular inspections of catchment areas Diversion of local stormwater flows Protection of waterways Runoff interception Security to prevent sabotage and tampering Water extraction and storage systems Use of available water storage during and after periods of heavy rainfall Appropriate location and protection of intake Appropriate choice of off-take depth from reservoirs Proper well construction including casing, sealing and wellhead security Proper location of wells Water storage systems to maximise retention times Roofed storages and reservoirs with appropriate stormwater collection and drainage Securing tanks from access by animals Security to prevent unauthorised access, sabotage and tapping and tampering 2. Water treatment After source water protection, the next barriers to contamination of the drinking-water system use water treatment processes. Source waters of very high quality may only require watershed protection and disinfection. Examples of treatment control measures: 3. Piped distribution systems Water entering the distribution system must be microbially safe and, ideally, should also be biologically stable. The distribution system must provide a secure barrier to post- treatment contamination as the water is transported to the user. Residual disinfection will provide partial protection against microbial contamination, but may also mask the detection of contamination through conventional faecal indicator bacteria such as E. coli, particularly by resistant organisms. Thus, water distribution systems should be fully enclosed and storages should be securely roofed with external drainage to prevent contamination. Backflow prevention policies should be applied and monitored. There should be effective maintenance procedures to repair faults and burst mains in a manner that will prevent contamination. Positive pressure should be maintained as far as possible throughout the distribution system. Appropriate security needs to be put in place to prevent unauthorised access and/or interference. 6. LIMITS AND MONITORING For each control measure it is important to first define the operational limits (range) which, as part of the overall process train, leads to the supply of water that meets the intended use (including the health targets). However, because it is rarely practical to measure the concentration of hazards directly, some other means of control measure performance needs to be identified and becomes the target of monitoring. Therefore, a relationship between control measure performance, as determined by measurable parameters, and hazard control performance needs to be established. This relationship can be established using theoretical and/or empirical studies Not all measurable properties of control measures are suitable for this type of monitoring. Only where the following criteria are satisfied it is possible to define operational limits for control measures: limits for operational acceptability can be defined; these limits can be monitored, either directly or indirectly (e.g., through surrogates); a pre-determined corrective action (response) can be enacted when deviations are detected by monitoring (see Chapter 8); the corrective action will protect water safety by bringing the control measure back into specification, by enhancing the barrier or by implementing additional control measures; and the process of detection of the deviation and completion of the corrective action can be completed in a timeframe adequate to maintain water safety. MONITORING PARAMETERS The parameters selected for operational monitoring should reflect the effectiveness of each control measure, provide a timely indication of performance, be readily measured and provide opportunity for an appropriate response. Some water quality characteristics can serve as surrogates (or indicators) for characteristics for which testing is more difficult or expensive. Conductivity, for example, is a widely used surrogate for total dissolved solids. OPERATIONAL LIMITS The water safety plan team should define the operational (or critical) limits for each control measure, based on operational parameters such as chlorine residuals, pH and turbidity, or observable factors, such as the integrity of vermin-proof screens. The limits need to be directly or indirectly measurable. Current knowledge and expertise, including industry standards and technical data, as well as locally derived historical data, can be used as a guide when determining the limits. Target or operational limits might be set for the system to run at optimal performance while the term critical limits might be applied when corrective actions are required to prevent or limit the impact of potential hazards on the safety and quality of the water. Limits can be upper limits, lower limits, a range or an envelope of performance measures. They are usually indicators for which results can be readily interpreted at the time of monitoring and where action can be taken in response to a deviation in time to prevent unsafe water being supplied. MONITORING Monitoring relies on establishing the ‘what’, ‘how’, ‘when’ and ‘who’ principles. In most cases, routine monitoring will be based on simple surrogate observations or tests, such as turbidity or structural integrity, rather than complex microbial or chemical tests. The complex tests are generally applied as part of validation and verification activities rather than in monitoring operational or critical limits. Monitoring plan The strategies and procedures for monitoring the various aspects of the water supply system should be documented. Monitoring plans should include the following information: parameters to be monitored; sampling location and frequency; sampling needs and equipment; schedules for sampling; methods for quality assurance and validation of the sampling results; requirements for checking and interpreting the results; responsibilities and necessary qualifications of staff; requirements for documentation and management of records, including how monitoring results will be recorded and stored; and requirements for reporting and communication of results.  7. MANAGEMENT PROCEDURES If monitoring detects that a process is operating outside of the specifications of the critical or operational limits there is a need to act to restore the operation by correcting the deviation. An important component of a water safety is the development of corrective actions which identify the specific operational response required following specific deviations from the set limits (operational and/or critical). CORRECTIVE ACTIONS AND INCIDENT RESPONSE The range of corrective actions can be diverse but, in an ideal system, the ability to change temporarily to alternative water sources is one of the most useful. More commonly, the use of backup disinfection plants or spot dosing may be used to correct disinfection system failure within the water supply. By ensuring that a contingency is available and promptly applied in the event of a deviation outside an operational or critical limit, safety and security of supply can be maintained. A corrective action might be initiated in response to deviations arising from events such as: non-compliance with operational monitoring criteria; inadequate performance of a sewage treatment plant discharging to source water; notification of chance events; spillage of a hazardous substance into source water; extreme rainfall in a catchment; unusual taste, odour or appearance of water. Corrective actions typically comprise: accountabilities and contact details for key personnel; clear description of the actions required in the event of a deviation; location and identity of the standard operating procedures and required equipment; location of backup equipment; relevant logistical and technical information. EMERGENCY MANAGEMENT PROCEDURES No matter how thorough the water safety plan it is possible that unforeseen events or deviations may arise for which no corrective action is in place. Under such circumstances there is a need to develop corrective actions without warning. An emergency response plan would not have specific definitions of the operational and critical limits that, if deviated from, trigger a corrective action. Rather, the plan would include a protocol for situation assessment and the declaration of situations that require activation of the emergency response plan. This would include personal accountabilities and categorical selection criteria. The selection criteria may include: time to effect; population affected; and nature of the suspected hazard. The success of emergency response depends on the experience, judgement and skill of the personnel operating and managing the drinking-water supply systems. The emergency response plans can be very broad and can include major regional disasters (such as earthquakes, floods, damage to electrical equipment by lightning strikes), accidents (spills in the watershed), damage to treatment plant and distribution system, and human actions (strikes, sabotage). Emergency response plans should be developed in consultation with relevant regulatory authorities and other key agencies, and should be consistent with national and local emergency response arrangements. Key areas to be addressed in emergency response plans include: response actions, including increased monitoring; responsibilities and authorities internal and external to the organisation; plans for emergency water supplies; communication protocols and strategies, including notification procedures (internal, regulatory body, media and public); and mechanisms for increased public health surveillance.  8. SUPPORTING PROGRAMMES Supporting programmes are activities that ensure the operating environment, the equipment used and the people themselves do not become an additional source of potential hazards to the drinking-water supply. They incorporate the principles of good process control that underpin the water safety plan. Codes of good operating, management and hygienic practices are essential elements of supporting programmes. These are often captured within standard operating procedures (SOPs) or system operating rules. They can include, but are not limited to; hygienic working practices documented in maintenance SOPs; training and competence of personnel involved in water supply; tools for managing the action of staff, such as quality assurance systems; securing stakeholder commitment, at all levels, to the provision of safe water; education of communities whose activities may influence water quality; calibration of monitoring equipment; and record keeping. Supporting programmes will consist almost entirely of items that water suppliers and handlers will ordinarily have in place as part of their normal operation. For most, the implementation of supporting programmes will involve: collation of existing operational and management practices; initial, and thereafter, periodic review and updating to continually improve practices; promotion of good practices to encourage their use; and audit of practices to check that they are being used, including taking corrective actions in case of non- conformance.  9. DOCUMENTATION AND RECORD KEEPING Documentation and records are essential for reviewing the adequacy of the water safety plan and the adherence of the water supply system to the plan. There will also be a range of records that will form part of the water safety plan setting up and implementation process as well as monitoring and any necessary corrective actions taken, incident response records, validation and verification. These can essentially be divided into four types of record: support documentation for developing the water safety plan; records generated by the water safety plan system; documentation of methods and procedures used; and records of employee training programmes. Water safety plan system records are kept to demonstrate adherence of the system to the water safety plan. By tracking records generated by the water safety plan system, an operator or manager can become aware that a process is approaching its operational or critical limit. Review of records can be instrumental in identifying trends and in making operational adjustments. Periodical review of water safety plan records is recommended so trends can be noted and appropriate actions decided upon and implemented.  10. VALIDATION AND VERIFICATION Validation should be targeted at the assessment of the scientific and technical inputs into the water safety plan. Validation should ensure that the information supporting the plan is correct and that the elements of the water safety plan will be effective, thus enabling conformity with health- based targets and public health policy. Verification may include review of monitoring control measures, microbiological and chemical testing, or review of the water safety plan overall to ensure that it is still accurate. This may be necessary, for instance, if there have been changes to processes or equipment. Thank you for your attention!!