Water safety plan as conceived by WHO can lead to prevention of pollution in each component of water supply chain which leads to ensuring safe drinking water. Risk assessment is one of the key components during the development of water safety plan, achieved by identifying hazardous events and estimating their risk towards implementing control measures. This study reports the risk assessment from catchment to consumers in Maiduguri water treatment plant in Northeast Nigeria. Tools such as the field visits, key informant interviews, questionnaire and water quality monitoring were used to identify the hazards and estimate their risk using semi-quantitative matrix. With the existing control measures, the study showed a total of 33 hazardous events; 5 in catchment, 16 in treatment plant, 6 in distribution system and 6 at consumers’ points. The risk score indicated 6 are of medium risk and 9 of high risk. Catchment activities, upgrade of treatment facilities and lack of routine maintenance in the treatment plant, pipeline damages in distribution lines, and consumers’ lack of hygiene knowledge and awareness were found to be the major contributory factors which affect the desired quality. Therefore participation and commitment by all relevant stakeholders are fundamental requisite to manage the identified health risks.
The safety of drinking water supply depends on a number of factors including quality of source water, effectiveness of treatment, integrity of the water distribution that transports water to consumers and the consumers themselves in proper handling of the water [
“The most effective means of securing the safety of a drinking water supply is through the use of a comprehensive risk assessment and risk management approach that encompasses all steps in the water supply from catchment to consumer; such approaches are known as water safety plan.”
Water safety plans are promoted and encouraged in the third edition of the WHO (2004) guidelines. The aim of the water safety plan is to protect public health and promote good practices such as preventing or minimizing water source pollution, reducing or removing pollutants through treatment processes and preventing its contamination during its storage, distribution and household connection and handling [
Catchment protection is the first stage in the production of safe drinking water [
early management of hazardous events at catchment would be an effective preventive measure in relation to water quality incidents in the drinking water supply.
Treatment process effectiveness requires proper operation and optimization, such as appropriate dosage of treatment chemicals; following standard operating and maintenance procedures and ensuring that all automated systems are working properly, and not adhering to these leads to contaminated water distributed to consumers. Many outbreaks of diseases have been reported that were due to failures within the treatment plant which could be avoided with simple risk management procedures [
Systems often receive too little attention despite disease outbreaks due to inadequate management of drinking water distribution systems. A Drinking water treatment plant can provide water that is safe for human consumption but its quality can be affected during movement through the water distribution system before arriving at consumers point [
The aim of water safety plan is not only to identify and improve water quality problems related to catchment, treatment and distribution, but also at consumers point, It was found that water treatment and supply utilities alone cannot ensure the provision of safe drinking water and protection against water borne disease as household plumbing systems, improper storage and handling also cause recontamination [
The concept of WSPs represent currently the modern system in the delivery of safe water and one of the several stages that is, most likely to be adopted by water industries in the future [
Whilst there are many sources of drinking water in Maiduguri, Maiduguri water treatment plant is one of the major sources covering about 60% of the entire metropolis. The integrity of this water supply is constrained by many factors in the catchment, treatment, distribution and consumers endangering the health of consumers. Based on previous studies by Dammo et al., [
The development of Water safety plan and implementation involves eleven modules which are as follows:
Module 1: Assembling the WSP team.
Module 2: Describing the water supply system.
Module 3: Identifying hazards.
Module 4: Assessing control measures and risks.
Module 5: Developing improvement plans.
Module 6: Defining control measure monitoring.
Module 7: Defining verification monitoring.
Module 8: Preparing management procedures.
Module 9: Developing supporting programmes.
Module 10: Planning periodic review of WSP.
Module 11: Revising WSP following incident.
This paper describes the results of risk assessment from catchment to consumers of Maiduguri water treatment plant which may serve as prominent guide for use in the development of the WSP.
Maiduguri, the capital of Borno State is located between latitude 10˚00' and 14˚00' north of the equator and longitude 11˚30' and 14˚45' east of the Greenwich Meridian, the state lies some 355 m above sea level and it occupies a total area of 50,778 sq km, lying within the Sudan-Sahel zone of Nigeria, it is the largest town in the North-Eastern area of Nigeria. The relief of Maiduguri lies on the vast open plain which is relatively flat or gently undulating. The landscape is developed on the young sedimentary rocks of the Chad formation. This formation is overlain by sand drifts which may be up to 90 meters thick. The extensive plain contains no prominent hill and attains an elevation of about 350 m above sea level.
The climate is characterized by two distinctive wet and dry seasons, which tend to be controlled by the inter-tropical discontinuity (ITD). The rainy season lasts for about five months (May-October). Available rainfall data reveal that annual rainfall average ranges between 500 mm and 750 mm while the intensity of rainfall ranges from 0.002 mm/hr - 112 mm/hr. The mean temperature both seasonally and diurnally varies from 25˚C - 36˚C, the hottest months being March and April with values between 39.80˚C and 40.70˚C. The corresponding minimum temperatures of 20.60˚C and 32˚C are in December and January.
The Maiduguri water treatment facility was completed in 1986 [
The study design was analytical and cross sectional, consisting of laboratory analysis, questionnaire survey, field visits and key informant interviews. Questions for the questionnaire survey were drafted in March 2017 and administered till the middle of April, Key Informant Interviews and site visits were conducted through months of April and May 2017 and continuous even after the sample collection and analysis, risk identification and analysis at the end of May 2017, data entry, results, discussion and conclusion were carried out then.
Water samples were collected from raw water source which was during the early time of the raining season (to determine the source of contamination), through various stages of the treatment processes, (to assess the effectiveness of treatment), along the distribution at some selected points where consumers fetch their water (to assess the integrity of distribution) and samples at household taps and storage containers of consumers (to determine the possibility of recontamination from human contact). The samples collected were then subjected to physical, chemical and microbiological analysis to ascertain their quality following standard methods.
1) Parameters measured
a) Physical: turbidity, temperature, electrical conductivity.
b) Chemical: pH, total hardness, total alkalinity, iron, zinc, lead, calcium, potassium, sodium, total dissolved solids, fluoride, chloride, sulphate, residual chlorine, nitrate, phosphate.
c) Microbiological: faecal coliforms and total coliforms counts;in addition presence of some non-coliforms bacteria were also examined.
2) Sampling number and locations
For physical and chemical parameters; a total of five samples were taken for analysis, sampling location and their appropriate labeling are given below:
Sample A: Raw water sample from catchment.
Sample B: Aerated water.
Sample C: Coagulated water.
Sample D: Filtered water.
Sample E: Final treated water.
And for Microbiological analysis; six samples were taken for total coliforms and faecal coliforms count (E. coli), and their locations are:
Sample 1: Final treated water at treatment plant,
Sample 2: 3.5 kilometers away from the treatment plant at Gwange area household tap,
Sample 3: At Gwange area household storage containers, (same house where sample 2 was taken),
Sample 4: 8.5 km kilometers away from Gwange area at London ciki public tap (end users),
Sample 5: At London Ciki area household storage,
Sample 6: At London Ciki public tap (same point as sample 4).
Note: Sample 4 and 6 were taken at the same location, but the samples were collected at different times; sample 6 was taken after 2 days of non supply (pipes were without water (empty); during this time some ingress of contamination through pipeline holes was seen arising from the open drains where these pipes were laid.).
3) Laboratory procedures
Laboratory analyses were carried out at four different laboratories for different parameters, namely:
a) Geochemistry lab at Geology Department (University of Maiduguri): Elemental analysis of some of the major Cations (Na, K, Ca, and Mg) were analysed using LAQUAtwin meter (Horiba Scientific), and Chloride and Hardness (C03 and HC03 determination) using titration, the reagents used for the titration of C03 and HC03 determination are Phenolphthalein 1% (1 g of Phenolphthalein in 100 ml alcohol), methyl-orange and 0.1N of H2S04, and for chloride determination are 250 ml conical flask, K2CrO4 (Potassium Chromate) as indicator and 0.02N Silver Nitrate (Ag2N03).
b) NAFDAC Laboratory in Maiduguri: here total alkalinity were analysed using titrimetry and iron, manganese, zinc, lead, fluoride, sulphate and phosphate analysed using Atomic Absorption Spectrophotometer (AAS, Model AA-6800 SHIM).
c) Veterinary Microbiology Laboratory (University of Maiduguri): the analysis of microbiological parameters of total coliforms and fecal coliform counts were carried out using total coliform count test method and most probable number method respectively. Materials used are EMB (Eosine Methylene Blue B agar) culture media, MacConkey broth, eAger count plate, test tubes and 0.85 percent normal saline solution.
d) Maiduguri Water Treatment Laboratory; parameters analysed were nitrate, total dissolved solids, temperature, electrical conductivity, pH and turbidity using HI 9829 multi parameter and measurement of residual chlorine using a DPD (Diethyl phenylene diamine) tablet method.
The Plant distribute Water to 20 areas within Maiduguri town comprising of low income and high income areas, hence 10 households were randomly selected from each area making a total of 200 questionnaires administered, the questionnaire was structured basically to determine the level of awareness of consumers regarding water quality management at their own level to ensure proper collection, storage, handling and usage of water at households, and also to explore the points of views, perceptions and satisfaction level regarding water service delivery both interms of quality and quantity by the Plant. Hence their socio-demographic characteristics, alternative sources of water and related aspects were studied. Information was also collected on whether health issues encountered in the past and present as a result of poor water supply, facts about the regularity of supply to consumers, type of household storage systems used, household treatment methods if any practiced, hygiene awareness and level of hygiene practiced, and also the extent of consumers knowledge regarding the treatment plant were studied.
Sanitary inspection visits were conducted for the catchment, treatment plant, and distribution chain and at consumers’ points, inspection such as catchment activities, areas surrounding water abstraction points, elements of treatment, structures and facilities of distribution network and household storage systems.
Discussions were conducted with staff of the water works in the various units, one (1) person to represent each unit making a total of 6 person interviwed such as from the administrators, Stores, Quality assurance, operations, electrical and mechanical unit, the interview was basically to have in-depth information on the type of water supply system, the operating techniques being applied and the competence of staff in the water works corporation, this helps in understanding of the entire water system towards predicting of some hazards and hazardous events as per the WHO WSP Module 2 guide. Hence information on Raw water source, treatment units/processes, various chemicals used for treatment, storage system, pumps and pumping, distribution system, available documents that describe the system (flow charts, operating techniques, etc.) control measures, previous historical water quality records (hazards events, outbreaks), quality assurance, laboratory, challenges, supporting programs, management procedures, environmental effects, monitoring, availability of trained staff, extend of water safety plan application, relation with the concerned official authorities (state ministries and agencies) were the discussed issues in the interview, the interview was conducted along with site visits for visual inspection which subsequently helps in hazard identification.
Risk assessment is one of the key stages during the development of water safety plan. It is achieved by identifying hazards following Modules 3 and estimating their risk as described in Module 4 which allows prioritizing human and financial resources toward improving control measures as a strategy for reducing health risks [
In accordance with the study design following Module 3, all the possible visible and hidden hazards that can compromise effective water delivery in terms of water quality and quantity, compliance with regulations, consumers’ acceptance and damage to facilities have been looked into thoroughly. The following 3 types of hazards have been looked into:
1) Physical Hazards (Denoted by P in the Matrix).
2) Chemical Hazards (Denoted by CH in the Matrix).
3) Microbial Hazards (Denoted by M in the matrix).
The identification was carried out based on site visits for visual inspection; review of the materials used in treatment, structures and facilities of distribution and household storage containers), key informant interviews (assessment of historic information and events, predictive information based on seasonal changes and knowledge of particular aspects of the treatment and supply system) review of consumers’ perceptions and water quality analysis results were all included in the hazards identification study.
For any hazardous event that can give rise to one, two or to all the three types of hazards, the risk associated is analyzed using semi quantitative matrix approach (
Consequences
a) Insignificant (no impact): Rating-1.
b) Moderate impact (aesthetics, adequacy of supplies, damage to facilities): Rating-2.
c) Catastrophic or significant impact (public health effect and compliance with regulations): Rating-3.
And the likelihood or frequency of occurrence of a particular hazardous event has been rated from 1 to 3 starting from the highest frequency to the lowest frequency in terms of possibility of the hazard occurring daily, weekly, monthly, seasonally and yearly.
Likelihood
a) Daily to weekly (almost certain): Rating-3.
b) Monthly to seasonally (possible): Rating-2.
c) Yearly and above (rare): Rating-1.
| Matrix | Severity categories | |||
|---|---|---|---|---|
| I (1) | II (2) | III (3) | ||
| Likelihood Categories | A (3) | M (3) | H (6) | H (9) |
| B (2) | L (2) | M (4) | H (6) | |
| C (1) | L (1) | L (2) | M (3) | |
| Risk score rating | Low (<3) | Moderate (3 - 6) | High (>6) | |
Risk analysis definition parameters: Likelihood categories A = daily to weekly (almost certain) B = monthly to seasonally (possible) C = yearly and above (rare) Severity categories I = significant risk/catastrophic: public health impact or regulation compliance impact, death or illness expected. II = medium: aesthetics or water quantity (consumers acceptance), damage to facilities III = NO impact or insignificant: Risk score categories High risk = urgent management attention needed Moderate risk = management attention needed Low risk = routine procedures and; Colours Low (L): <3 (Denoted by Green Colour); Medium (M): 6 - 9 (Denoted by Yellow Colour); High (H): >6 (Denoted by Red Colour).
The knowledge of consequence and likelihood were derived based on the study design, (water treatment plant staff opinion, past events, previous studies and experience of Operation and Maintenance staff and review of consumers’ survey and results of water quality analysis studies)
1) Risk scoring
Using semi quantitative method shown in
Risk = likelihood × severity
First, the risk score was calculated completely ignoring all the control measures (activities or polices applied to mitigate risk) that actually are in place in the water supply system known as raw risk. site visits were conducted to identify the existing control measures and to assess the effectiveness of the control measures (validation), which was done by reviewing the maintenance and monitoring records, water quality results, consumers survey and field inspection. Then risk score was then recalculated and referred as residual risk taking into account all the control measures that exist in the system, keeping check on that particular hazardous event whether the control measure is effective based on the findings from the validation of the control measures, so the severity and frequency of that hazardous event becomes low which ultimately brings down the risk score of that hazardous event.
As shown in
The hazardous events with the high risk level were mainly at the catchment and consumers points. At the catchment, hazardous events were associated with socio-economic activities (crop production, cattle rearing, open human defecation, domestic activities and recreations) for which no control measures were present as the catchment is not a protected zone. At consumers point of use most hazardous event were due to lack of hygiene awareness leading to improper collection, storage and handling of waters as revealed by the by questionnaire survey of which all 200 responded. Within the treatment plant, the hazardous events were due to facilities upgrade and maintenance, whereas along the distribution line, damages in drinking water pipes leading to the leakages and ingress of contamination were the major threat to effective conveyance of water to consumers.
| 1) Catchment | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Hazardous event | Issues to consider and hazards associated with. | Raw risk | Risk rating | Basis for selecting the likelihood of the hazard and its consequences | Existing Control measure and its effectiveness | Residual risk | Risk rating | ||||||
| Li | C | S | Li | C | S | H, M or L | |||||||
| Cattle rearing around source water | Cryptosporidium and other infectious organisms introduced into water (M) | 3 | 3 | 9 | H | Li: site visits C: cryptosporidium infection may harm human health | ECM: No | 3 | 3 | 9 | H | ||
| Farming activities along the river bank | Pesticide, nitrate washed into raw water (CH) | 3 | 3 | 9 | H | Li: site visit, historical water quality showing high nitrate C: nitrate, pesticides in high concentration harms health and incompliance regulation | ECM: No | 3 | 3 | 9 | H | ||
| Human defecation into the raw water | E-coli, faecal coliforms introduced into raw water (M) | 3 | 3 | 9 | H | Li: site visit, human settlement present near raw water and no toilets C: faecal microorganisms may harm the public health | ECM: No | 3 | 3 | 9 | H | ||
| Dumping of refuse | Solids, debris into water (P) | 3 | 2 | 6 | M | Li: site visit and key informant interview C: debris into treatment plant system might clog filters, etc. | ECM: screens provided at intake side E: yes; no floating debris within treatment | 1 | 2 | 2 | Lo | ||
| Algal blooms during hot season. | Changing color, turbidity, taste and odour, and heavy algae growth in treatment tanks (M) | 2 | 3 | 6 | M | Li: site visits key informants survey C: record shows high turbidity in the hot season affecting the aesthetics of water | ECM: No | 2 | 3 | 6 | M | ||
| People bathing in the water | Contamination of raw water (CH, M) | 3 | 3 | 9 | H | Li: site visits, historical records C: contamination from bathing | ECM: No | 3 | 3 | 9 | H | ||
| Bokoharam attack at intake side | Interrupted pumping of water, lost operators live | 2 | 3 | 6 | M | Li: key informant interview (some villages around the intake site has been attacked several times) C: terrorist may harm plant operators at the raw water intake site | ECM: soldiers deployed at intake side E: yes Several attack to villages near has been repelled with victory | 1 | 3 | 3 | Lo | ||
| 2) Treatment | |||||||||||||
| Pre-liming pump breakdown | Temporary hardness and acidity removal not achieved | 3 | 2 | 6 | M | Li: site visits, water quality analysis. C: imbalance pH causes corrosion to pipes of treatment facilities | ECM: No | 3 | 2 | 6 | M | ||
| Natural Aeration process | Inadequate in achieving aeration benefit (CH) | 3 | 2 | 6 | M | Li: water quality analysis C: DO, odour and taste not removed (aesthetics) | ECM: No | 3 | 2 | 6 | M | ||
| Alum pipe network clogging | Interrupted coagulation treatment (P, CH, M) | 2 | 3 | 6 | M | Li: operators interview (it takes 6 months before clogging occurs) C: loss of coagulation leads to untreated water Supplied to consumers | ECM: Treatment process is halted to restore problem E: Yes | 1 | 2 | 2 | Lo | ||
| Frequent Alum pumps break down. | Loss of coagulation treatment (P, CH, M) | 2 | 3 | 6 | M | Li: it takes 3 months before it happens says operators, visual inspection reveals many broken alum pumps C: untreated water supply | ECM: Treatment process is halted to restore the problem E: Yes (but frequent breakdown need to be stopped) | 2 | 2 | 4 | M |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Trident pipe clogged | Improper sedimentation (P, CH, M) | 3 | 2 | 6 | M | Li: sanitary inspection C: leading to contamination | ECM: fishing road is used to flush it. E: effective | 1 | 2 | 2 | Lo |
| Trident pipe breakage | Improper sedimentation (P, CH, M) | 2 | 3 | 6 | M | Li: sanitary inspection, discussion with plant operators C: it reduces the rate of sedimentation leading to contamination | ECM: Replacement is done for any breakage E: yes | 2 | 1 | 2 | Lo |
| Decantation pipe blockage | Inadequate sludge removal from sedimentation tank (P, CH, M) | 1 | 2 | 3 | Lo | Li: operators interview (blockage occurrence is very rare) C: decantation pipe blockage only flushes sedimentation tank of flocculated material | ECM: No | 1 | 2 | 3 | Lo |
| Corrosion and algal blooms in sedimentation tanks | Contamination of treated water (CH, M) | 3 | 3 | 9 | H | Li: visual inspection, water quality results (increased in concentration of some water parameters). C: contaminated water supply affects health | ECM: sedimentation tank is washed every 90 days E: no; problems observed by field visits | 3 | 3 | 9 | H |
| Frequent Back washing Pump failures | Loss of backwashing, Clogging of filters which lead to reducing water quantity and quality (P, CH, M) | 3 | 3 | 9 | H | Li: discussion with plant operators reveals that C: it affects both quality and quantity of water | ECM: problem is restored with immediate action E: Yes but the frequent break down need to be curtailed | 3 | 2 | 6 | M |
| Filter beds exceeded life span | Improper filtration (P, CH, M) | 3 | 3 | H | Li: site visits and discussion with plant operators, water analysis results (increased in concentration of some water parameters). C: improperly filtered water supply to the public | ECM: No | 3 | 3 | 9 | H | |
| Corrosion and algal blooms in Filtration tanks | Contamination of water (CH, M) | 3 | 2 | 6 | M | Li: site visits and visual inspection. C: contaminated supply | ECM: No | 3 | 2 | 6 | M |
| Leakages in backwashing machine through gasket | Reducing water quantity and corrosion (CH, M) | 3 | 2 | 6 | M | Li: visual inspection C: loss of water supply, damage to facilities | ECM: No | 3 | 2 | 6 | M |
| Head loss to know when to back wash. | Loss of signal by operators the time required to back wash filter | 3 | 2 | 6 | M | Li: visual inspection during site visit C: irregular backwashing time. | ECM: No | 3 | 2 | 6 | M |
| Chlorine dosing pump break down | Loss of disinfection (M) | 3 | 3 | 9 | H | Li: visual inspection C: supplying water without disinfecting affects public health. | ECM: Manual chlorination E: No (chlorine over dosing/under dosing indicated by consumers survey affecting aesthetics) | 3 | 2 | 6 | M |
| Post-liming pump break down | High acidity of treated water, corrosion (CH) | 3 | 2 | 6 | M | Li: visual inspection C: aesthetics, damage to facilities | ECM: No | 3 | 2 | 6 | M |
| Contact tank | High sludge in Contact tank, contamination of treated supply (P, CH, M) | 3 | 3 | 9 | H | Li: visual inspection, interview and water quality analysis (increased in concentration of some water parameters). C: supply of contaminated water | ECM: No | 3 | 3 | 9 | H | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Underground reservoir | High sludge in underground reservoir, contamination of treated supply (P, CH, M) | 3 | 3 | 9 | H | Li: visual inspection, interview, water quality analysis (increased in concentration of some water parameters). C: supply of contaminated water | ECM: No | 3 | 3 | 9 | H | |
| Pumping station | Leakages at Pumping station | 3 | 2 | 6 | M | Li: visual inspection C: damage to pumping materials from corrosion | ECM: No | 3 | 2 | 6 | M | |
| Laboratory Services | Substandard laboratory | 3 | 3 | 9 | H | Li: discussion with plant operators, visual inspection C: loss of quality control | ECM: ICRC NGO is currently facilitating it. E: No (full analysis has not yet started) | 3 | 2 | 6 | M | |
| Power | Constant generator failure | 3 | 3 | 9 | H | Li: personal experience, staff’s experience C: loss of supply, treatment failure | ECM: standby generator provided by government, transformer with 33 KV by ICRC E: yes (constant power observed) | 1 | 3 | 3 | Lo | |
| Communication with consumer | Lack of communication between plant management and consumers | 3 | 2 | 6 | M | Li: consumers survey C: communication is essential in effective water supply, such as communication when there is leakage, outbreak, pipe burst, etc | ECM: No | 3 | 2 | 6 | M | |
| 3) Distribution | ||||||||||||
| Illegal connections | Loss of supply, drop in pressure | 3 | 2 | 6 | M | Li: site visits during consumers survey, consumers complaints review C: illegal connection affects water quantity by reducing pressure | ECM: special task force assigned to cut-off any E: No (such connection observed and politics, sentiments involved) | 3 | 2 | 6 | M | |
| Leakages | Loss of water quantity, ingress of contamination (P, CH, M) | 3 | 3 | 9 | H | Li: visual inspection during site visit C: leakages allow contamination to enter pipe, reduces water demand, pressure and requires urgent attention | ECM: repairs by staff immediately E: No; (so many leakages observed in site visits | 3 | 3 | 9 | H | |
| Pipe bursting | Loss of supply, water disaster | 1 | 3 | 3 | Lo | Li: it rarely happens; from plant operators C: it requires urgent attention | ECM: action is taken immediately to control it E: Yes; history of pipe burst is minimal with no serious destruction | 1 | 2 | 2 | Lo | |
| Pipes passing through drainage system | Corrosion, Ingress of contamination from pipe perforations (P, CH, M) | 3 | 3 | 9 | H | Li: visual inspection of sites, water quality results: high turbidity(12.8NTU) and presence of Pseudomonas aeruginosa in collected water) C: public health concern. | ECM: No | 3 | 3 | 9 | H | |
| Intermittent supply | Insufficient water quantity, ingress of contamination from pipe perforations. | 3 | 3 | 9 | H | Li: consumers survey C: water quality analysis shows bacterial contamination from storing water which is a threat to health | ECM: No | 3 | 3 | 9 | H | |
| Gravity problems | Loss of supply; that water does not reach some areas due to drop in pressure and causes insufficient water quantity. | 3 | 2 | 6 | M | Li: site visits, consumers complain, C: due to gravity many areas are getting little or no water. | ECM: No | 3 | 2 | 6 | M |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Construction activities | Blockages of pipeline with construction debris, breakages of pipeline allowing entry of contamination. | 3 | 2 | 6 | M | Li: site visits, customers complaint C: loss of supply | ECM: No | 3 | 6 | M | |
| 4) Consumers | |||||||||||
| Unhygienic practice during collection | Introduction of microbial pathogen into water (M) | 3 | 3 | 9 | H | Li: visual inspection during consumers survey (drop of foreign materials into water), water analysis (presence of coliforms in water C: bacterial contamination affects the public health | ECM: No | 3 | 3 | 9 | H |
| Collection vessels designed for dipping | Introduction of microbial pathogens from dipping hands (M) | 3 | 3 | 9 | H | Li: consumers questionnaire, site visits, water analysis results (presence of staphylococcus) C: public health concern | ECM: No | 3 | 3 | 9 | H |
| Lack of disinfecting storage tanks regularly | Allow algae growth and other microorganisms (M) | 3 | 3 | 9 | H | Li: sanitary inspection visits, consumers survey showed low level of home treatment practices and water analysis showed bacterial growth in tanks (Corynebacteria Specie, Bacillus Albus) C: not disinfecting storage tanks allows the growth of pathogens, thus effects on public health. | ECM: No | 3 | 3 | 9 | H |
| Using dipper with short or no handle to collect water | Possible contamination from dirty hands being immersed into water(M) | 3 | 3 | 9 | H | L: visual inspection during site visits, water quality results (presence of Staphylococcus albus in water) C: public health | ECM: No | 3 | 3 | 9 | H |
| Storage, and collection points accessible to children | Possible microbiological contamination by children introducing foreign materials into water (M). | 3 | 3 | 9 | H | L: consumers survey, visual inspection, water quality results (showed Escherichia coli in stored water) C: public health concern | ECM: No | 3 | 3 | 9 | H |
Keys-Lo: Low (denoted by green colour); H: High; Li: Likelihood; C: Consequences; ECM: Existing control measure; E: effectiveness of control measure; M: microbiological hazards; CH: chemical hazards; P: physical hazards; ICRC: International Committee of Red Cross.
Based on the risk assessment therefore, an improvement plans for the uncontrolled hazardous events which still remain on the higher side even after the control measures installed or with no control measure are being suggested in the proper format as per WSP Module 5, the improvement plans clearly pin point the agencies responsible to execute the plan in a clearly mentioned time frame as shown in
Improvement plan/mitigation measures
| Issue identified | Improvement required | Responsibility | Time frame |
|---|---|---|---|
| Farming activities along the river bed | Agricultural activities in the river bank should be moved away to some considerable distance away from the catchment. | State Ministry of Environment, Ministry of Agriculture, Ministry of Water Resources | 1 year |
| Human defecation into the raw water | Strictly prohibiting open defecation, Awareness programs to educate people about proper sanitary practices, Sanitary toilet should be provided to people at the catchment | Ministry of Health, State Ministry of Environment, | Uncertain |
| Cattle rearing | Cattle rearing should be restricted to some considerable distance away from the raw water intake side, fencing to restrict them | Ministry of Agriculture, Environment and Water Resources, | 1 year |
| Dumping of refuse | Awareness programs should be conducted | BOSEPA LGA (Community Health Officers), NGOs | Uncertain |
| Recreational activities | All recreational activities in and around the raw water source should be prohibited | Ministry of Tourism and Culture, Water Resources | 6 months |
| Seasonal variation | Alum dosage should be increased in the treatment process during hot season and use chemicals such as copper sulphate to control algae | Water treatment plant management | Immediately |
| Pre-liming pump breakdown | Brand new, latest and strong pump should be provided | Water treatment plant management | 1 year |
| Aeration process ineffective | Effective mechanical aerator should be provided | Water treatment plant management | 2 years |
| Alum pumps break down | Latest strong alum pump should be installed | Water treatment plant management | 1 year |
| Corrosion and algal blooms in sedimentation tanks | Always maintain a balanced pH in the treatment systems, use copper sulphate to control algae and regular cleaning of the tank | Water treatment plant management and operators | Immediately |
| Frequent Back washing pump failure | Latest backwashing machine should be installed | Water treatment plant management and operators | 1 year |
| filter beds exceeded life span | filter beds should be changed completely | Water treatment plant management and operators | Immediately |
| Corrosion and algal blooms in Filtration tanks | Always maintain a balanced pH in the treatment systems, use copper sulphate to control algae | Water treatment plant management and operators | Immediately |
| Leakages in backwashing machine through gasket | Leakages should be controlled, by sealing the joint | Water treatment plant management and operators | Immediately |
| Chlorine dosing pump break down | Latest chlorine pump should be installed | Water treatment plant management and operators | 6 months |
| Post-liming pump break down | Latest post liming pump should be installed | Water treatment plant management and operators | 1 year |
| Heavy sludge in Contact tank | Should be evacuated completely | Water treatment plant management and operators | 2 months |
| Excessive sludge in Underground reservoir | Should be evacuated completely | Water treatment plant management and operators | 2 months |
| Leakages at Pumping station | All leakage point should be repaired | Water treatment plant management and operators | 3 months |
| Lack of communication between plant operators and consumers | Communication system between plant operators and consumers should be enhanced (through area office) | Water treatment plant management | Uncertain |
| Illegal connections | Effort should be intensified by cutting off any illegal connection with no sentiment | Water treatment plant management and staff | Immediately |
|---|---|---|---|
| Leakages | All leakage point should be repaired | Water treatment plant management | Immediately |
| Pipes passing through drainage system | Drainage water should be evacuated on regular basis before water may reach pipe level, | Ministry of Environment | Immediately |
| Intermittent supply | The design capacity of the plant should increased by implementing the second phase of the water supply to ensure constant supply | Ministry of Water Resources, Water treatment plant management | 3 years |
| Destruction of underground pipeline from other activities such as digging for road construction, Bridges, drainage evacuation etc. | All blocked and destroyed pipelines should be repaired | Ministry of Works, Water Resources | 2 years |
| gravity problems | Design capacity of the plant should be increased by implementing Second phase of the water supply to increase pressure so that water may rich consumers on high hill | Ministry of Water Resources | 3 years |
| Unhygienic practice during collection | Awareness program should be conducted to educate consumers | Ministry of Education | Uncertain |
| collection vessels designed for dipping | Long handle vessels should be distributed to consumers and encourage them to support the use, if possible all collection vessels designed for dipping should be redesigned | Ministry of Water Resources, NGOs, LGA (Primary Health Care) | 3 years |
| Lack of cleaning storage tanks regularly | Awareness programs to consumers to clean their tanks on regular basis | Ministry of Water Resources, NGOs, LGA (Primary Health Care) | Uncertain |
| Lack of disinfection of storage tanks at home | Awareness programs about dangers of not disinfecting tanks, distribution of Aqua tablets, water guards | Ministry of Water Resources, NGOs, LGA (Primary Health Care) | Uncertain |
| Using dipper with short or no handle | Awareness programs | Ministry of Water Resources, NGOs, LGA (Primary Health Care) | Uncertain |
| Storage, and collection points accessible to children | Awareness programs | Ministry of Water Resources, NGOs, LGA (Primary Health Care) | Uncertain |
The Maiduguri water supply has been compromised due to several human and natural factors. The raw water supply at the catchment showed high levels of nitrate and faecal pollution as indicated by the presence of E. coli. The treated water showed high turbidity and colour. The distribution system showed leakages which resulted in poor quality of the otherwise well treated water. This study has carefully evaluated various hazards and hazardous events together with risk assessment using quantitative risk matrix. Further it was observed that at the consumer end the risk is higher as evident from increased coliforms presumably arising from household sources. In the communities, the hygiene is rather low as children dip their hands and also many of the water drawing cups are indiscriminately kept on floor or other unclean surfaces. From this point of view, the water safety plan comes handy to pin down the factors responsible for unhygienic conditions thereby proffering solutions for better water supply.
In this study, risk assessment through evidence based analysis shows the importance of its role as a supporting tool for ensuring water quality, since it identifies the hazardous events, and the analysis of control measures provided evidence of the measures’ effectiveness and identified the need for improving existing measures and formulating new measures to generate risk reduction as part of WSP’s focus. Therefore, participation and commitment of all stakeholders (water service providers, health, agriculture, water resources and environment entities, consumers, administrators, and catchment community) are fundamental strategies to avoid/reduce health risks by defining appropriate mitigation plans (corrective actions, infrastructures, designs, supporting programs). Some viable mitigation plans are recommended to the water treatment facility (
The authors declare no conflicts of interest regarding the publication of this paper.
Mustapha, M., Sridhar, M.K.C., Coker, A.O., Ajayi, A. and Suleiman, A. (2019) Risk Assessment from Catchment to Consumers as Framed in Water Safety Plans: A Study from Maiduguri Water Treatment Plant, North East Nigeria. Journal of Environmental Protection, 10, 1373-1390. https://doi.org/10.4236/jep.2019.1010081