Environmental geology outline -
groundwater quality and contamination: answers to questions.
What might people
want to know about the water they drink and use (water quality
- color, turbidity, temperature: for aesthetic reasons, visual clue to quality.
- pH: (aggressive
acidic waters can leach metals from aquifers or pipes).
- fecal coliform count:
measure of possible pathenogenic (microbial) content, Giardia,
- BOD (Biological Oxygen demand) and DO
(Dissolved oxygen): measure of amount
of organics that would deplete oxygen in the water when biodegraded.
General want DO>BOD. Aeration treatment.
- TDS (Total Dissolved Solids): 500-1000 ppm drinkable (given no toxic components);
primarily Mg, Na, Ca, K, Cl, SO4, CO3 ions;
- concentration of specific compounds; nitrates, atrazine, lead (the list is very long).
Science of toxicology sets health limits.
What are examples
of point sources in urban environment (the urban landscape from
an environmental perspective)?
- gas stations and other storage tanks (LUST program - Leaky Underground Storage Tanks)
- old landfills.
- old dumps.
- evaporation ponds and beds: associated with industry, Griggs and Gilchrist indicate
an EPA survey found 180,000 such ponds and beds in U.S. of which
77% were unlined.
- chemical spills.
- mafia disposal sites.
- dry cleaner facilities (Vickers in Omaha).
- many more.
What are some
clean up methods? Have made tremendous
progress in last two decades in this technology.
- slurry walls and pump and treat (e.g., Rocky
- porous reaction walls (Fe filings).
- specific treatments = air stripping, bioremediation,
activated carbon filters, chemical neutralization.
proving very powerful.
- differs for types of contaminants.
- cost per site? At Rocky Mountain the cost
is > $30 million.
there any superfund sites in Nebraska?
- Grand Island
- industrial corridor of the Platte.
Love Canal, New
York: classic case history
- Hooker Electrochemical Company dumped about
21,000 tons of various toxic wastes in old canal from 1942-1952.
- Hooker sold 16 acres to Niagara Falls School
Board for $1, with disclaimer absolving them from all future
damage claims in connection with the chemical wastes.
- housing development built on site.
- 1970s surface leakage of contaminants as
barrels rusted and leaked.
- eventually area condemned, >500 families
moved, $30 million spent in remediation.
- studies showed significant abnormal chromosonal
- three times as high miscarraige rate.
- brought national awareness of the issue.
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