HONR 297 Environmental Models

HONR 297Environmental Models Chapter 2: Ground Water 2.1: Background

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.

Ground Water and the Saturated Zone • Definition: • 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!

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.

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

Contaminated Ground Water • Suppose 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.

Example 1 • Suppose 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?

Example 1 • Solution: 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!

Example 1 • Potential 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.

Leaking Tank Issues • Suppose a leaking tank, such the one in Example 1, has been discovered – besides contaminated ground water, what other issues or problems might arise? • 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.

Leaking Tank Issues • Lawsuits • Neighbors exposed to contaminated drinking water may develop health risks. • Property values may decrease. • Negligence on the part of the gas station owner. • Government Agencies • May impose substantial fines. • May take away license to sell gas (my guess).

Leaking Tank Issues • Liability Insurance • Is there any (most likely yes, probably required)? • Is there enough to cover claims? • What type of coverage – short or long term? • 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?

Leaking Tanks as a “Global” Problem • Situations 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.

Sources of Ground Water Contamination • In 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!

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 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.”

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.”

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).”

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.”

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.”

Ground-Water Models • Clearly, 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 earth’s surface and therefore not directly observable, 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!

References • Superfund WebPages (for material on slides 15 – 18) • http://www.epa.gov/superfund/index.htm • http://www.epa.gov/superfund/about.htm • http://www2.epa.gov/enforcement/superfund-enforcement • http://www2.epa.gov/enforcement/superfund-liability • IDEM Web Page and Mission Statement • http://www.in.gov/idem • http://www.in.gov/idem/5215.htm • Water Table and Charts • http://ga.water.usgs.gov/edu/watercyclegwdischarge.html • Charles Hadlock, Mathematical Modeling in the Environment, Chapter 2, Section 2.1

HONR 297 Environmental Models