Chapter 8: Groundwater

Question 1

What are the four parts to Groundwater?

Answer 1

1. Unsaturated Zone: air, water, soil. Water is held in tension and considered unavailable.
2. Capillary Fringe: up to 100% saturated, but water held in tension.
3. Water Table: upper bound of Saturated Zone
4. Saturated Zone: Water and soil - water flows as groundwater.

Question 2

What is an aquifer?

Answer 2

A saturated layer permeable enough to allow water flow. Water can be pumped economically.

Question 3

What is an aquitard?

Answer 3

Saturated layer not permeable enough for easy water flow. Water can’t be pumped out economically.

Question 4

What is Groundwater?

Answer 4

Water contained in interconnected pores below water table in an aquifer.

Question 5

What is Groundwater Flow?

Answer 5

The movement of water through openings in sediment and rock.

Question 6

What does Artesian mean?

Answer 6

A confined aquifer with water that flows upward out of a well.

Question 7

What does Perched mean?

Answer 7

Groundwater above a permeable layer - usually above aquifer.

Question 8

What is the hydraulic gradient?

Answer 8

The slope of water table to difference in hydraulic head b/w 2 points (i)

Question 9

What is Porosity?

Answer 9

ratio of volume of voids to total volume

Question 10

What is Effective Porosity?

Answer 10

ratio of interconnected pore spaces to bulk volume

Question 11

What is hydraulic head?

Answer 11

surface elevation minus distance to water table

Question 12

What is pressure head?

Answer 12

Depth of well from surface minus distance to water table from surface

Question 13

What is elevation head?

Answer 13

surface elevation minus depth of well

Question 14

What is the difference between Darcy Flux and groundwater velocity?

Answer 14

Darcy velocity assumes no soil in cross section (open pipe flow), whereas groundwater velocity takes into account the porosity (ie. soil in the way)

Question 15

What are the three methods of contaminant transportation?

Answer 15

1. Advection: due to groundwater flow
2. Dispersion: due to irregular flow paths
3. Diffusion: due to concentration gradient

Question 16

What is Plume?

Answer 16

Dissolved contaminants

Question 17

What are some attributes of dispersion?

Answer 17

• micro, macro, and mega scales
• smaller pores = higher velocity
• higher velocities = higher dispersion

Question 18

What are some attributes of diffusion?

Answer 18

• Contaminant plume moves from high concentration to low
• Important in low velocity soils (clay/bedrock)

Question 19

What is Adsorption?

Answer 19

The property of a solute to attach to a surface of a solid

Question 20

What is Absorption?

Answer 20

The property of a solute to attach to surface of a solid, then penetrate the solid

Question 21

What is Retardation?

Answer 21

When contaminant velocity is slower than groundwater velocity.

Question 22

What are NAPLs?

Answer 22

Non-Aqueous Phase Liquids

Question 23

What are LNAPLs and DNAPLs?

Answer 23

Less dense than water - LNAPL
More dense than water - DNAPL

Question 24

What are some attributes of NAPLs?

Answer 24

• Ganglion form as NAPL migrates
• Immobile
• Long term source of groundwater contamination
• Difficult to remove or remediate

Question 25

What are the steps in Contaminated Site Management?

Answer 25

1. Site Investigation 2. Remediation Plan & Implementations 3. Confirmation of Remediation - certification 4. Long-term Monitoring

Question 26

What are some remediation technologies for groundwater?

Answer 26

- Fluid pumping - Mass destruction - Enhanced fluid pumping - Enhanced bioremediation

Question 27

What does Groundwater Pumping involve?

Answer 27

- Uses advective treatment methods to remediate - Contaminant and fluid brought to surface for treatment - Hydrodynamic/hydraulic control

Question 28

What is SVE?

Answer 28

Air Flushing: - Soil Vapour Extraction - Unsaturated Zone: Soil remediation

Question 29

What is Air Sparging?

Answer 29

Air Flushing: - Saturated Zone: Plume remediation

Question 30

What are PRB's?

Answer 30

Permeable Reactive Barriers. They passively intercept contaminants passing through the barrier where they react and are broken down by a reactive material.

Question 31

What is ISCO?

Answer 31

In-situ chemical oxidation. Oxidation converts hazardous contaminants to non-hazardous compounds that are more stable.

Question 32

What are common oxidizing agents used?

Answer 32

- Ozone - Hydrogen Peroxide - Permanganate

Question 33

What are some benefits of ISCO?

Answer 33

- applicable to a variety of soil types - Can treat VOC's and SemiVOC's - Rapid destruction - No significant waste

Question 34

What is MNA?

Answer 34

Monitored Natural Attenuation Naturally Occurring processes that act without human intervention to reduce contaminants in soil/groundwater.

Question 35

What are Reactive Zones?

Answer 35

Zones created by injection of air/oxygen that treats contaminants through biodegredation.

Question 36

What is Thermal Remediation?

Answer 36

Use of heat to destroy contaminants. - Conduction heating - Steam injection

Question 37

What is Phytoremediation?

Answer 37

Use of plants to address contamination issues.