HONR 297Environmental ModelsChapter 2: Ground Water2.1: Background

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Question!Question: Suppose you dig a

hole in the ground – what will eventually happen if you continue downwards vertically?

Answer: Eventually you will encounter water – this may happen close to the surface or you may need to dig (or drill if there is rock) hundreds of feet.

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Ground Water and the Saturated ZoneDefinition:

◦The saturated zone is the area below ground where all the spaces between soil particles or cracks in the rock are full of water.

◦The water in this zone is called ground water.Note:

◦Used as a noun, people usually write “ground water” (two words).

◦Used as an adjective, people usually write “ground-water” or “groundwater” (one word).

◦We will adhere to this convention!

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Ground Water Moves!It is interesting to note that

ground water is not stationary – it is moving, just like rivers or streams on the surface!

Usually ground water moves much more slowly than surface water – for example at rate of inches or feet per day or even slower.

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Ground Water and Global Water Distribution

Water source

Water volume,in cubic miles

Water volume,in cubic kilometers

Percent of total water

Percent of total freshwater

Fresh groundwater

2,526,000

10,530,000 0.8% 30.1%

Groundwater5,614,00

023,400,000 1.7% --

Total global water

332,500,000

1,386,000,000

-- --

Source: Gleick, P. H., 1996: Water resources. In Encyclopedia of Climate and Weather, ed. by S. H. Schneider, Oxford University Press, New York, vol. 2, pp.817-823.

Table and charts courtesy of USGS: http://ga.water.usgs.gov/edu/watercyclegwdischarge.html

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Contaminated Ground WaterSuppose that at some point

underground the ground water is contaminated with some toxic substance.

What does the fact that the ground water moves imply?

The contamination also moves, potentially causing widespread underground zones with groundwater that cannot be used for drinking or other uses.

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Example 1Suppose an underground storage tank

that holds gasoline for a service station leaks very slowly and is undetected for three years.

The gasoline moves vertically through the soil until it reaches ground water, at which point the gasoline contaminates (i.e. mixes with) and moves with the ground water.

How far could the contamination have spread horizontally, given that the ground water flows at a rate of five feet per day?

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Example 1Solution: The distance traveled by

the ground water is given by◦Distance = Rate x Time

Distance = (5 ft/day) x (3 yr) x (365 day/yr)= 5475 feet

Since there are 5280 feet in one mile, this means that the contaminated water could have moved horizontally a little over one mile in three years!

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Example 1Potential Ramifications

◦Existing drinking water wells could be ruined.

◦No new wells for drinking could be drilled.

◦Property values could decrease.◦Major cleanup needed once the

contamination has been discovered.

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Leaking Tank IssuesSuppose a leaking tank, such the one in

Example 1, has been discovered – besides contaminated ground water, what other issues or problems might arise?

1. Technical ◦ How far has the contaminant spread?◦ How much actual contamination can be

cleaned up?◦ Possibly the soil near the tank (depending on

the depth to groundwater) can be removed, most likely not all affected soil.

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Leaking Tank Issues

2. Lawsuits◦ Neighbors exposed to

contaminated drinking water may develop health risks.

◦ Property values may decrease.◦ Negligence on the part of the gas

station owner.

3. Government Agencies◦ May impose substantial fines.◦ May take away license to sell gas

(my guess).

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Leaking Tank Issues4. Liability Insurance

◦ Is there any (most likely yes, probably required)?

◦ Is there enough to cover claims?◦What type of coverage – short or long term?

5. Bankruptcy (and other related issues)◦ Overwhelming costs to clean up.◦ Difficulty selling property in future.◦ Potential mortgage default.◦ Will bank be able to sell?◦ Who assumes responsibility if sold?

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Leaking Tanks as a “Global” ProblemSituations like that of the gas station with

a leaking underground storage tank are not uncommon – they occur throughout the US (and beyond, in all countries).

Think about all the chemicals stored in tanks that may leak – not only those at gas stations, but others as well (dry cleaners, lawn services, farms, factories, etc.).

A prime example of this is Love Canal – see p. 10 in our text for more detail.

Part 1 Part 2

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Sources of Ground Water ContaminationIn the late 1970’s, after sites like Love Canal

began to make national headlines, people looked around and began to realize that incidents like this were not isolated – other sources of potential ground-water contamination include:◦ Toxic or hazardous waste dumps◦ Municipal landfills◦ Oiling of gravel roads◦ Underground storage tanks◦ Leaking chemical pipelines◦ Etc. …

Because ground water moves so slowly, often it took years for problems to surface!

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Superfund In 1980, concern for the environment went

“mainstream” when congress enacted a law known as the “Superfund Act”.◦ “Superfund is the name given to the environmental

program established to address abandoned hazardous waste sites.

◦ It is also the name of the fund established by the Comprehensive Environmental Response, Compensation and Liability Act of 1980, as amended (CERCLA statute, CERCLA overview).

◦ This law was enacted in the wake of the discovery of toxic waste dumps such as Love Canal and Times Beach in the 1970s.

◦ It allows the EPA to clean up such sites and to compel responsible parties to perform cleanups or reimburse the government for EPA-lead cleanups.”

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Superfund“The Superfund cleanup process is complex. It involves the steps taken to assess sites,

place them on the National Priorities List, and establish and implement appropriate cleanup plans.

In addition, the Agency has the authority◦ to conduct removal actions where immediate

action needs to be taken; ◦ to enforce against potentially responsible parties;◦ to ensure community involvement; ◦ involve states; ◦and ensure long-term protectiveness.”

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Superfund“The Superfund Enforcement

program gets Superfund sites cleaned up by finding the companies or people responsible for contamination at a site, and negotiating with them to do the clean up themselves, or to pay for the clean up done by another party (i.e., EPA, state, or other responsible parties).”

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Superfund“The Superfund law … imposes liability on parties

responsible for, in whole or in part, the presence of hazardous substances at a site.

Superfund Liability is: ◦ Retroactive - Parties may be held liable for acts that

happened before Superfund's enactment in1980. ◦ Joint and Several - Any one potentially responsible

party (PRP) may be held liable for the entire cleanup of the site (when the harm caused by multiple parties cannot be separated).

◦ Strict - A PRP cannot simply say that it was not negligent or that it was operating according to industry standards. If a PRP sent some amount of the hazardous waste found at

the site, that party is liable.”

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IDEM Each state has at least one agency that deals with

environmental issues. In Indiana, one of these is the Indiana Department of

Environmental Management (IDEM) IDEM’s Mission Statement:

◦ “IDEM's mission is to implement federal and state regulations to protect human health and the environment while allowing the environmentally sound operations of industrial, agricultural, commercial and government activities vital to a prosperous economy.”

◦ “Environmental protection in Indiana has come a long way since 1986, when IDEM was established. Since then, IDEM has grown to a staff of 900, and employs some of Indiana's most qualified engineers, scientists and environmental project managers specializing in air, land, pollution prevention and water quality issues.”

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Ground-Water ModelsClearly, the study of ground water is very

important to the evaluation of environmental risk, with many interested parties!

Since much of what goes on with ground water is beneath the surface of the water, where it cannot be seen or directly observed, mathematical models have been developed that allow a significant amount of information to be gleaned from drilling wells and collecting ground-water samples.

In the rest of this chapter we will look at some of the ideas behind these models!

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References YouTube Videos

◦ http://www.youtube.com/watch?v=vKIM9sE0t6I◦ http://www.youtube.com/watch?feature=endscreen

&v=MXSE9kcBQCI&NR Superfund WebPages (for material on slides

14 – 17)◦ http://www.epa.gov/superfund/index.htm◦ http://www.epa.gov/superfund/cleanup/index.htm◦ http://www.epa.gov/compliance/cleanup/superfund

/index.html◦ http://www.epa.gov/compliance/cleanup/superfund

/liability.html IDEM Mission Statement

◦ http://www.in.gov/idem/5215.htm Water Table and Charts

◦ http://ga.water.usgs.gov/edu/watercyclegwdischarge.html