What went wrong?

May 2000

Background • Drinking Water in Ontario is from two sources:

• Surface Water (Great Lakes) • About 70% of Canadians rely on surface water

• Groundwater (wells or springs) • About 30% of Canadians rely on groundwater(Guelph, Waterloo, Cambridge, rural areas)

• An aquifer is an underground formation of permeable rock or loose material that can produce useful quantities of water when tapped by a well

•The purpose of water treatment is to: • Reduce the risk from pathogens and solutes to an acceptable level (treatment attempts to eliminate microbial, chemical and radiological contaminants )

• The water is of high aesthetic quality (in terms of odour, taste, clarity and colour)

Water Treatment Process for the City of Toronto

1. The water intake pipes extend into Lake Ontario and collect raw water

1. The water intake pipes extend into Lake Ontario and collect raw water

2. SCREENING: travelling screens used to remove large debris and objects

2. SCREENING: travelling screens used to remove large debris and objects

3. Chlorine added to lake water to kill micro-

organisms. This stage is called pre-chlorination.

3. Chlorine added to lake water to kill micro-

organisms. This stage is called pre-chlorination.

3b. Alum is added to clump the small particles, such as

silt to form floc(larger groups of particles).

3b. Alum is added to clump the small particles, such as

silt to form floc(larger groups of particles).

http://www.canadiangeographic.ca/atlas/themes.aspx?id=watersheds&sub=watersheds_waterforlife_withdrawaluses

Water Treatment Process Con’t4. The heavy flocs drop out of

the water in a settling tank and collect at the bottom.

These are removed from the water.

4. The heavy flocs drop out of the water in a settling tank and collect at the bottom.

These are removed from the water.

5. Filtration: a series of layer of gravel, fine sand (to remove floc,

algae, slit) and carbon or anthracite (to remove odour and taste producing chemicals). Also remove physical, chemical, and

biological impurities.

5. Filtration: a series of layer of gravel, fine sand (to remove floc,

algae, slit) and carbon or anthracite (to remove odour and taste producing chemicals). Also remove physical, chemical, and

biological impurities.

6. Purified water goes to holding basin prior to

distribution. Safe levels of chlorine added and excess chlorine is removed sulphur dioxide. The city of toronto

adds fluoride to prevent cavities.

6. Purified water goes to holding basin prior to

distribution. Safe levels of chlorine added and excess chlorine is removed sulphur dioxide. The city of toronto

adds fluoride to prevent cavities.

7. Add ammonia to water. Ammonia combines with the

remaining chlorine to stabilize the chlorine and

keep water safe as it leaves the plant to distribution

pipes.

7. Add ammonia to water. Ammonia combines with the

remaining chlorine to stabilize the chlorine and

keep water safe as it leaves the plant to distribution

pipes.

8. Treated water is tested regularly to ensure quality8. Treated water is tested regularly to ensure quality

Water is distributed to

you guys

Water is distributed to

you guys

What went wrong? • Source of the contamination was manure that had been spread on a farm near Well 5

• Heavy rains in Southern Ontario (May 8- 12) caused runoff of this manure that leaked into well 5

•All of the water drawn from the well came from a very shallow area between 5.4 m and 7.7 m below the surface

• This water was drawn from highly fractured bedrock where bacteria entered

CONTAMINATION IN DRINKING

WATERThe presence of Campylobacter jejuni and

E.Coli in drinking water

E.coli O157:H7• Some E.coli cause disease

• Toxin-producing strain (poison called verotoxin)• binds to receptors on human kidney, gut, brain cells• leads to cell death

•SYMPTOMS: •Severe stomach cramps•Diarrhea (often bloody)•Vomiting•Nausea•Headache•Little or no fever

•Symptoms appear 3-5 days after infection and clear within 5-10days

• In children and elderly, it leads to many complications (renal failure, dehydration, HUS.), these complications can lead to death

Campylobacter jejuni• A bacteria that proliferates the bowel wall

•SYMPTOMS: • Diarrhea• Cramping• Fever • Abdominal Pain

• Those exposed become ill

• Symptoms appear within 2-5 days and recovery takes about 10 days

•0.05% of those who are infected have nerve damage and reactive arthritis

• 7 fatal deaths and several thousand (2,300) ill

• This incident was PREVENTABLE !

• NO daily monitoring of the chlorine residual levels • Expected dose of chlorine 0.5 mg/L after 15 minutes of contact time under normal conditions➞Walkerton operators put in less

• Lab tests had shown bacteria in the water but this information not relayed to the people of Walkerton in time

• How much did this incident cost the Canadian Government overall?

• How much did it cost to fix the water-treatment plant?

Consequences

• RESULT: increased consumption of bottled water

•What impact does this have on the environment?

How does this relate to you?According to Region of Peel:

• Water must meet:• Microbiological Standards

• No E. coli • Chemical Standards

• Standards are expressed as maximum acceptable concentrations in mg/L

• EX: Lead 0.010 mg/L or Arsenic 0.025 mg/L or Fluoride 1.5 mg/L

• Radiological Standards• Standards are expressed as maximum acceptable concentrations in Becquerels/L

• Ex: Uranium-238: 4.0 Bq/L

Conclusion • Therefore, due to improper operating practices:

• not monitoring chlorine residual levels

• not using the adequate chlorine dose

• Well 7 did not have a functioning chlorinating system a week earlier

• falsifying information • These contaminants were able to pass through the water treatment process and be distributed to consumers undetected.