Chapter 5B: Groundwater – why we should be concerned

---

To the teacher

Purpose

To help students grow aware of how we threaten our supply of groundwater and to consider ways we can lessen the stress on this resource.

Subject areas

Science, Environmental Studies, Art

Procedure

1. Review groundwater with the students. Point out that it's easy to believe our groundwater supply is safe from the pollution which affects surface water, but this is not the case. Just because we can't see groundwater, doesn't mean we aren't affecting its quality.
   
   
   • We need to take precautions to protect groundwater because there are many threats to its purity – some of these threats are from people and some from natural causes.
     
     
2. Brainstorm with the students for possible threats to the groundwater supply. Ask how their own households contribute. Depending on where they live, some of the following topics may be discussed:
   
   
   • leaky sewer lines
   • septic systems
   • leaky oil tanks or pipelines
   • spills/leaks from industrial chemicals
   • landfills
   • mill tailings in mining areas
   • chemicals for preserving wood
     
     
   Understanding the quality of groundwater and how it becomes polluted is important because:
   
   
   • it is difficult to identify the sources of groundwater pollution and when we do find pollution, it is difficult to clean up. Why? It is not easily accessible and it travels slowly.
     
     
   • it is easier to prevent pollution than to clean it up.
     
     
   • we need to understand that what we do now will help ensure that our children and grandchildren will not have a problem.
     
     
3. Discuss "orphan" wells. There are thousands of these across Canada where the wells have run dry and they have been left open – to become a source of contamination.

Vocabulary anthropogenic corroded potable saltwater intrusion

References

• Freshwater Series A-5: Groundwater – Nature's Hidden Treasure
• A Primer on Fresh Water: "Water – Underground"

Student information

There's so much groundwater, why worry?

Suppose you are researching groundwater pollution and you come across this sentence: "Groundwater becomes contaminated when anthropogenic substances find their way to the groundwater zone." Huh? What in the world does that mean? It helps when you know that "anthropogenic" means "people-created". The question is, what are the people-created substances that contaminate groundwater?

Read the following story about a small town in Ontario, which could just as easily be a community anywhere.

Residents of Manotick, a town near Ottawa, can tell you about a groundwater supply that has been polluted by toxic chemicals from an anthropogenic source. The polluted water in some of their households is so bad that they have been told not to shower with the water, let alone drink it. What is the source? Some people are speculating that the chemicals are coming from an old dry-cleaning plant.

How we contaminate groundwater

Did you know? Leaks of petroleum products have been increasing over the past two decades because underground steel tanks installed in the 1950s and 1960s have become corroded. This causes about half of them to leak by the time they are 15 years old. Often you will see your local garage closed for repairs as old tanks are dug up and replaced with newer fiberglass ones.

Other sources of groundwater contamination include leaky septic systems, landfills, industrial wastes, livestock wastes, mill tailings in mining areas, sludge disposal, graveyards, runoff of salt and other chemicals on roadways, coal tar, pesticides/fertilizers, and atmospheric fallout found in rain and snow.

Groundwater pollution from natural causes

Don't think that people are the only causes of groundwater contamination. Nature adds contaminants too. Some of these are too much iron, manganese, and arsenic; uraninium in bedrock; and saltwater intrusion, which occurs when seawater seeps into groundwater near coastal areas.

The good news and the not-so-good news

The good news is that groundwater is generally safer than surface water for drinking because soil and rocks provide natural processes that filter and purify the water. The bad news is that these processes don't work when anthropogenic substances reach the water supply. Other bad news is that since groundwater moves so slowly, once it becomes contaminated, the pollutants take a very long time to leave the system.

The news media often come up with stories about underground pollution which may have started years ago – it's very hard to trace the cause of some pollution (ask the people from Manotick, Ontario). And even if the polluter is identified, the business may have closed long ago, so we can't get the guilty party to pay. Guess who ends up paying?

Cause for concern

So, the message is – we should be concerned about our groundwater supply. Consider the following:

• The health of a million or more Canadians may be affected by drinking contaminated well water.
  
  
• It is often impossible to restore polluted groundwater to potable quality because it is difficult to reach and it moves so slowly through the soil.
  
  
• Since 1979, over 500 wells in New Brunswick have been contaminated by leaking petroleum tanks.
  
  
• Organic herbicides sprayed along transmission corridors for power lines have contaminated bedrock wells in Quebec.

Groundwater and deep wells can be contaminated by waste disposal sites as the following diagram shows.

And don't forget "orphan wells"

In some parts of the country, people overuse the groundwater supply (or there may be a drought) and this causes the water table to drop. Wells run dry because they cannot reach the water. Some of these wells which run dry permanently are abandoned and are known as "orphan wells." Sometimes, instead of being boarded over, these wells are left open and, unfortunately, some people use them to dump wastes in so they become contaminated. Many of the contaminants find their way back into the groundwater supply.

Are we doing anything about cleaning up the groundwater we have polluted?

All levels of government in Canada are starting to take some actions to protect our water supply, but there is still a long way to go. Although groundwater is hidden, it is just as important as the sparkling lakes and rivers in our postcard image of Canada. Instead of concentrating on cleaning up, we must prevent contamination in the first place. For example:

• leaking underground storage tanks should be replaced by tanks that will not corrode
  
  
• landfills should be located where they will not contaminate underlying groundwater
  
  
• hazardous materials should not be stored where they can spill into recharge areas
  
  
• orphan wells should be boarded up so they do not become handy disposal sites
  
  
• what do you think?

Learning activities

Activity 1 – Environmental Studies

Your information sheets talk about ways we can prevent pollution of our groundwater. The suggestions are aimed mostly at industries. What can we do in our households? (Some municipalities have already begun helping householders take care of waste materials.)

• Draw up a list of things we can do, such as taking hazardous household substances to the waste disposal area.
  
  
• Prepare a report or a speech.

Activity 2 – Science

Take another look at natural causes of groundwater pollution:

• arsenic
• iron
• manganese
• uranium
• saltwater intrusion

Take one natural cause and research to find out about it. For example, what is arsenic? What effects does arsenic have on people? Or, how can saltwater intrude on groundwater? What's the problem, it's all water, isn't it?

Activity 3 – Art

Create your own comic strip character to give tips for protecting our groundwater supply. Use your character in a poster.

Activity 4 – Environmental Studies, Art

• Look back at the different ways that groundwater becomes polluted and how this affects people.
  
  
• Get poster board and markers from your teacher and design posters to inform people about the dangers of pollution to groundwater.
  
  
• On your poster show ways that this pollution can be avoided.

---

| What's New | About Us | Topics | Publications | Weather | Home |

The Green LaneTM, Environment Canada's World Wide Web site

Important Notices