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Midterm

ENH 424 Midterm: ENH 424 Midterm Review NINE PAGES LONG
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Department
Environmental Health
Course Code
ENH 424
Professor
Marilyn Lee

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ENH 424 Midterm Review
Lecture 1-Introduction
Drinking water in Canada
o 89% of Canadians rely on municipal water systems, 9% use private wells
o Guelph/Waterloo use ground water aquifers rather than lake water
Water-borne illness in Canada
o Estimated 100,000 illnesses/year
o No systematic collection and surveillance is fragmented/outbreaks not always reported
Burden of water-borne illness
o Globally 1.8 billion people use faecally contaminated drinking water source
Walkerton Outbreak
o May-June 2000, 65% of population was hospitalized with gastrointestinal infections ,
resulting in 7 deaths
o Had significant public health and economic impacts
o Brought considerable attention to water quality issues in Ontario
o Operators lacked proper training and expertise, MOE inspection failed to detect poor
operator practices
o Preventable by use of continuous chlorine residual/turbidity monitors
Multi-barrier approach
o Advocated by Health Canada to protect drinking water quality
Lecture 2-Drinking Water Legislation, Systems and Standards
Municipal water treatment plants
o Coagulation and Flocculation
Chemicals (alum, iron, salts) added to aggregate smaller particles and form
larger ones through coagulation
Floulatio asi stirs ater, partiles further lup ito flos
o Sedimentation
Gravity causes flocs to settle to bottom, can then be removed
o Filtration
Conventional-most common, dual-media filter of anthracite & sand
Direct-no sedimentation process, requires low turbidity water
Slow sand (gravity filtration) and diatomaceous earth (pressure filtration)-
mostly for water of low turbidity
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find more resources at oneclass.com
Membrane-microfiltration and ultrafiltration, frequently require some source of
pre-treatment
o Disinfection/Distribution
primarily chlorine but sometimes UV or ozone included
other chemicals may be added to prevent distribution systems corrosion
fluoride may be added to prevent tooth decay
free chlorine residual-hypochlorous acid considered powerful disinfectant, low
levels maintained in drinking water distribution systems to ensure safety of
water after it is treated
Chloramination-application of ammonia and chlorine to produce a combined
chlorine residual (in the form of monochloramine), weak disinfectant but
sometimes used as it is highly persistent and less likely to form by-products
Drinking Water Legislation
o Ont. Reg. 170 covers sampling, testing, disinfection, reporting requirements for
municipal drinking water systems enforced by MOECC inspectors
o MOHLTC oversees small drinking water systems (SDWS) under Ont. Reg. 319/08
Designated Facilities
o Provide drinking water to people more at risk to illness, must follow special
requirements such as schools, health care facilities, restaurants, parks, campgrounds,
seiors failities, urseries, uiersities/olleges, eergey shelters
SDWS: Ont. Reg. 319/08
o Any place where general public has access to a washroom, drinking fountain, shower
o Hotels, seasonal trailer parks w less than 5 connections, community centers, places of
worship, golf clubs, provincial parks, commercial facilities
o Must have a designated trained operator and notify MOH before construction or
alteration and receive written permission before operating
o Must make any test results available for public inspection during business hours
o For seasonal systems (closed more than 60 days consecutively)
Sample for E. Coli
Notify MOH with opening date, contact info, test results
o Risk Assessment
Categorized as high, moderate or low risk usig MOHLTC ‘isk Categorizatio
(RCat) tool
High risk systems inspected every two years
Moderate/low risk systems inspected every four years
RCat considers source water, sampling history, treatment/distribution,
operations, users
o *Directives-required actions for operator based on RCat assessment, SDWS operators
may be required to
Install treatment devices
Establish specific frequencies, locations, methods of sampling
Sample specific biological, chemical, radiological or other parameters
Conduct other operational tests
Maintain specific records
Meet specified training requirements
Post/maintain warning signs for users to not consumer water (MOH approved)
o Adverse events-operators immediately report every adverse observation
(contamination, back flows, inappropriate water filtration) and adverse test results
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find more resources at oneclass.com
o Treatment
Required for surface water supplies, optional for groundwater supplies
Must be in continuous operation when water is supplied/maintained
Must maintain chlorine residual of 0.05mg/L or 0.25mg/L chloramine
Water treatment must be cut off if other treatment is used
Adequate supply must be stored safely and securely nearby
o Sampling
Generally taken at point where water enters distribution system
Chlorine residual samples taken anytime microbiological sample are taken
All testing to be done in licensed labs
Operators to follo orretie atios id a aderse oseratio/test result
occurs such as
Checking/fixing equipment
Shock chlorination
Flushing distributive system
Notifying users to boil water/use alternate source
Resampling and testing
Notifying MOH
Drinking Water Standards: Ontario
o Ont. Reg. 169/03 lists enforceable standards in drinking water
o Includes Maximum Acceptable Concentrations (MAC), aesthetic objectives (AO) and
operational guidelines (OG)
Drinking Water Guidelines: Canada
o Published by Health Canada, updated regularly and posted online
o To be considered for guidelines contaminants should meet all of the following criteria
Exposure could lead to adverse health effects in humans
Frequently detected or could occur in a large number of drinking water supplies
Could be found in drinking water levels sufficient to cause adverse health effects
Microbiological Standards
o Monitoring for all pathogens that could be present not technically or economically
feasible, faecal indicator bacteria used to verify microbiological safety of drinking water
E. Coli must not be detectable
Enteric protozoa 2-3 log reduction according to O. Reg. 170/03, minimum 3 log
reduction according to Health Canada
Indicator Organisms
o E. Coli indicates recent faecal contamination
o Total coliforms used to determine how well drinking water system is operating, can
survive and grow in distribution system so may not indicate contamination
o Municipal treatment plants should be tested weekly for E. Coli/total coliforms
o SDWS should be sampled once every 3 months
o Detection of E. Coli indicates inadequate treatment
o Detection of total coliforms in consecutive samples from the same site or more than
10% of samples in a given period should be investigated
Enteric Viruses and Protozoa
o Commonly associated with human waterborne illness
o Can survive for extended periods in water, high infectious
o Should be controlled using multi-barrier approach
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find more resources at oneclass.com

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Description
ENH 424 Midterm Review Lecture 1-Introduction Drinking water in Canada o 89% of Canadians rely on municipal water systems, 9% use private wells o Guelph/Waterloo use ground water aquifers rather than lake water Water-borne illness in Canada o Estimated 100,000 illnesses/year o No systematic collection and surveillance is fragmented/outbreaks not always reported Burden of water-borne illness o Globally 1.8 billion people use faecally contaminated drinking water source Walkerton Outbreak o May-June 2000, 65% of population was hospitalized with gastrointestinal infections , resulting in 7 deaths o Had significant public health and economic impacts o Brought considerable attention to water quality issues in Ontario o Operators lacked proper training and expertise, MOE inspection failed to detect poor operator practices o Preventable by use of continuous chlorine residual/turbidity monitors Multi-barrier approach o Advocated by Health Canada to protect drinking water quality Lecture 2-Drinking Water Legislation, Systems and Standards Municipal water treatment plants o Coagulation and Flocculation Chemicals (alum, iron, salts) added to aggregate smaller particles and form larger ones through coagulation Flocculation basin stirs water, particles further clump into flocs o Sedimentation Gravity causes flocs to settle to bottom, can then be removed o Filtration Conventional-most common, dual-media filter of anthracite & sand Direct-no sedimentation process, requires low turbidity water Slow sand (gravity filtration) and diatomaceous earth (pressure filtration)- mostly for water of low turbidity Membrane-microfiltration and ultrafiltration, frequently require some source of pre-treatment o Disinfection/Distribution primarily chlorine but sometimes UV or ozone included other chemicals may be added to prevent distribution systems corrosion fluoride may be added to prevent tooth decay free chlorine residual-hypochlorous acid considered powerful disinfectant, low levels maintained in drinking water distribution systems to ensure safety of water after it is treated Chloramination-application of ammonia and chlorine to produce a combined chlorine residual (in the form of monochloramine), weak disinfectant but sometimes used as it is highly persistent and less likely to form by-products Drinking Water Legislation o Ont. Reg. 170 covers sampling, testing, disinfection, reporting requirements for municipal drinking water systems enforced by MOECC inspectors o MOHLTC oversees small drinking water systems (SDWS) under Ont. Reg. 319/08 Designated Facilities o Provide drinking water to people more at risk to illness, must follow special requirements such as schools, health care facilities, restaurants, parks, campgrounds, seniors facilities, nurseries, universities/colleges, emergency shelters SDWS: Ont. Reg. 319/08 o Any place where general public has access to a washroom, drinking fountain, shower o Hotels, seasonal trailer parks w less than 5 connections, community centers, places of worship, golf clubs, provincial parks, commercial facilities o Must have a designated trained operator and notify MOH before construction or alteration and receive written permission before operating o Must make any test results available for public inspection during business hours o For seasonal systems (closed more than 60 days consecutively) Sample for E. Coli Notify MOH with opening date, contact info, test results o Risk Assessment Categorized as high, moderate or low risk using MOHLTC Risk Categorization (RCat) tool High risk systems inspected every two years Moderate/low risk systems inspected every four years RCat considers source water, sampling history, treatment/distribution, operations, users o *Directives-required actions for operator based on RCat assessment, SDWS operators may be required to Install treatment devices Establish specific frequencies, locations, methods of sampling Sample specific biological, chemical, radiological or other parameters Conduct other operational tests Maintain specific records Meet specified training requirements Post/maintain warning signs for users to not consumer water (MOH approved) o Adverse events-operators immediately report every adverse observation (contamination, back flows, inappropriate water filtration) and adverse test resultso Treatment Required for surface water supplies, optional for groundwater supplies Must be in continuous operation when water is supplied/maintained Must maintain chlorine residual of 0.05mg/L or 0.25mg/L chloramine Water treatment must be cut off if other treatment is used Adequate supply must be stored safely and securely nearby o Sampling Generally taken at point where water enters distribution system Chlorine residual samples taken anytime microbiological sample are taken All testing to be done in licensed labs Operators to follow corrective actions id an adverse observation/test result occurs such as Checking/fixing equipment Shock chlorination Flushing distributive system Notifying users to boil water/use alternate source Resampling and testing Notifying MOH Drinking Water Standards: Ontario o Ont. Reg. 169/03 lists enforceable standards in drinking water o Includes Maximum Acceptable Concentrations (MAC), aesthetic objectives (AO) and operational guidelines (OG) Drinking Water Guidelines: Canada o Published by Health Canada, updated regularly and posted online o To be considered for guidelines contaminants should meet all of the follow
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