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7, Water Pullution (AQUIFERS ( Unconfined aquifer: between capillary…
7, Water Pullution
AQUIFERS
Ground water volumes recharged by rainwater, snow melt, etc.
Water in unsaturated zone: vadose water (not available for human use)
Water in saturated zone: ground water
Upper boundary of saturated zone: water table
Transition area: capillary fringe
Saturated geologic layer permeable for easy flow of water: aquifer
Unconfined aquifer: between capillary fringe and aquitard (confining layer)
Pumped well
Confining aquifer: between two aquitards
Under pressure
Artesian well
Flowing if below water level
Water storage in aquifer function of aquifer porosity
Page 31
EXAMPLES OF HOW ENGINEERING ACTIVITY
AFFECTS SOCIETY
Itai-itai disease (spinal/joint pain, kidney damage, bone softening)
Cadium poisoning from mining operations
1910 discharge
1912 disease identified
2012 final cleanup of Jinzū River Basin concluded
Soil Fumigant Metam Sodium
Train carriage derailed in Dunsmuir, California
1991
19 000 gallons
1 Million fish died
Trees lining river died
41 mile plume of contaminant
Love Canal
Originally built for hydroelectric
electricity generation in 1890
1,6km long by 15m wide by 12m
deep
Filled with water, clean
Became a dumping site for municipal
refuse in 1920
1942 canal drained and lined with
clay
Hooker Electrochemical Company
dumped chemical waste
Caustics, alkalines, chlorinated
hydrocarbons
1953, filled with sand and
vegetation
1954: site for schools, low
cost housing
1962: Clay layer cracked
1976: Sumps showed high
levels of toxins
Birth defects, epilepsy,
miscarriages
1974-1978: 56% of
children born had at least 1 birth defect
1979: 33% population had
chromosomal damage
Ghost town
CONTAMINANTS IN GROUNDWATER
Considered surface water contamination
Controlling spread of infectious disease
Reducing BOD wastes
Removal of nutrients causing cultural eutrophication
Groundwater contamination principal concern:
Toxic chemicals
Nonaqueous-Phase Liquids (NAPL’s)
Do not dissolve well in water
Dense
Chlorinated solvents (dry cleaning, metal degreasing)
Light
Fuel hydrocarbns (crude oil, benzene)
LNAPL’s
Unsaturated zone
Dissolve into water in pores
Volatilize with air in pores
Absorbed into soil
Saturated zone
Form a layer of contaminant that floats on the water
DNAPL’s
Unsaturated zone
Same as LNAPL’s
Saturated zone
Sink to form a relatively impermeable layer at bottom of aquifer
Slowly dissolve into passing groundwater
!Page 35-36
STRATIFICATION AND DISSOLVED OXYGEN
Dissolved oxygen affected by
thermal stratification and eutrophication
Epilimnion DO rich
Reaeration and
Photosynthesis
Ice forms, reaeration and
photosynthesis may not provide DO
Hypolimnion DO poor
Cut off from the epilimnion
due to stratification
Only have photosynthesis in
a clear oligotrophic lake
Anaerobic in summer
months due to lack of DO
Page 29
