L.8 - Groundwater

Question 1

Define Groundwater:

Answer 1

subsurface water that occurs beneath water table in soils and geologic formations that are fully saturated

Question 2

Where can groundwater discharge to?

Answer 2

stream, lake, river, ocean

Question 3

Define Unsaturated Zone:

Answer 3

water, air, and soil. Water is held in tension and considered unavailable

Question 4

Define Capillary Fringe:

Answer 4

up to 100% saturated but water is held in tension

Question 5

Define Water Table:

Answer 5

upper bound of saturated zone

Question 6

Define Saturated Zone:

Answer 6

water and soil. Water flows as groundwater

Question 7

What is the unsaturated subsurface zone also called?

Answer 7

Vadose zone

Question 8

What is the saturated subsurface zone known as?

Answer 8

Phreatic zone

Question 9

Define Aquifer:

Answer 9

saturated layer that is permeable enough to allow water to easily flow through it. Water can be pumped out at an economical rate

Question 10

Define Aquitard:

Answer 10

saturated layer that is not permeable enough for water to flow through it. Water can’t be pumped out at an economical rate

Question 11

Define an Artesian:

Answer 11

confined aquifer with water that flows upward out of a well (no pumping needed)

Question 12

Define Perched:

Answer 12

groundwater above a low-permeability layer (usually above an aquifer)

Question 13

Define Groundwater (r/ aquifer):

Answer 13

water that flows between interconnected pores located below the water table in an aquifer

Question 14

Define Groundwater Flow (r/ aquifer):

Answer 14

the movement of water through openings in sediment and rock (occurs in saturation zone)

Question 15

Define Porosity:

Answer 15

ration of volume of voids to total volume

Question 16

Define Effective Porosity:

Answer 16

ratio of interconnected pore spaces to the bulk volume

Question 17

Define Hydraulic Gradient:

Answer 17

slope of water table or difference in hydraulic head between two points

Question 18

What does Darcy’s Law state?

Answer 18

the rate of groundwater flow is controlled by hydraulic gradient and permeability or hydraulic conductivity of the aquifer materials (assumes linearity between flow rate and hydraulic gradient)

Question 19

Define Hydraulic Conductivity:

Answer 19

soil and water property that describes the ease with which soil pores allow water movement

Question 20

What is the difference between darcy flux and groundwater velocity?

Answer 20

darcy flux assumes there is no soil in cross-sectional area while for groundwater velocity, soil porosity is taken into account

Question 21

What are the 4 contaminant transport processes?

Answer 21

1) Advection
2) Dispersion
3) Diffusion
4) Sorption

Question 22

Define Advection:

Answer 22

contaminant transported due to groundwater flow (moves at the same speed as the water body)

Question 23

Define Dispersion:

Answer 23

contaminant transported due to irregular flow paths (smaller pores=higher velocity=higher dispersion)

Question 24

Define Diffusion:

Answer 24

contaminant flow due to concentration gradient (moves from high concentration to low concentration)

Question 25

Describe the groundwater dispersion scales:

Answer 25

1) micro-scale: due to differing pore sizes
2) macro-scale: due to differing hydraulic conductivities on a local scale\
3) mega-scale: due to regional changes in hydraulic conductivities, recharge and discharge points

Question 26

Define Sorption:

Answer 26

refers to the property of the solute dissolved to either attach to the surface of the solid (adsorption) or penetrate the solid (absorption)

Question 27

Talk about NAPLs:

Answer 27

• Non-Aqueous Phase Liquids
• they do not readily dissolve in water
• when blobs form as NAPLs they become long term contaminats, do no flow, and difficult to remove

Question 28

List the steps involved in contaminated sites management:

Answer 28

1) Question, could the site be contaminated
2) Site Investigation
3) Remediation Plan and Implementation
4) Confirmation of Remediation
5) Long-Term Monitoring

Question 29

List some groundwater remediation technologies:

Answer 29

1) Fluid pumping technologies
2) Mass destruction technologies
3) Enhanced fluid pumping technologies
4) Enhanced bioremediation technologies

Question 30

What does slurry consist of?

Answer 30

a mixture of soil, bentonite, and water

Question 31

What causes rebound/tailing? (gw p&t)

Answer 31

• Adsorption
• Back Diffusion
• NAPL ganglion

Question 32

What is Air Flushing remediation technology?

Answer 32

soil vapour extraction

Question 33

What is PRBs remediation technology?

Answer 33

permeable reactive barriers, passive interception and in situ treatment of dissolved contaminants in groundwater (ex. sulphate reduction wall)

Question 34

What is ISCO remediation technology?

Answer 34

In-situ chemical oxidation, oxidation chemically converts hazardous contaminants into non-hazardous or less toxic compounds that are more stable, less mobile (ex. ozone, hydrogen peroxide)

Question 35

What are some advantages for ISCO?

Answer 35

1) applicable to variety of soil types and grain sizes
2) applicable to treat VOCs and Semi VOCs (>90%)
3) rapid destruction/degradation of contaminants (90% in minutes)
4) produces no significant wastes

Question 36

What is MNA remediation technology?

Answer 36

Monitored natural attenuation, naturally-occurring processes in soil and groundwater without human intervention, reduce the mass, toxicity, volume, mobility of contaminants

Question 37

How are reactive zones created?

Answer 37

created through injection of air or oxygen over some period of time to treat/immobilize contaminants through biodegradation

Question 38

How is Thermal remediation technology used?

Answer 38

heat can destroy contaminants
techo.:
1) electrical resistivity heating
2) conduction heating
3) steam injection

Question 39

What is Phytoremediation remediation technology?

Answer 39

uses plants to address contaminant issues, used to 1) containment and control 2) removal and destruction

Question 40

What are some other remediation technologies?

Answer 40

1) Soil washing
2) Oil-water separator