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Enviro 7060 > Final study terms (ground water) > Flashcards

Final study terms (ground water) Flashcards

1
Q

definition of unsaturated zone

A

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

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2
Q

definition of water table

A

upper bound of the saturated zone

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3
Q

definition of saturated zone

A

water and soil. water flows as groundwater

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4
Q

definition of capillary fringe

A

up to 100% saturated but water is held in tension

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5
Q

definition of aquifer

A

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

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6
Q

definition of aquitard

A

saturated layer that is not permeable enough to allow water to flow easily through it. water cannot be pumped out at an economical rate

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7
Q

definition of artesian

A

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

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8
Q

definition of perched

A

groundwater above a low permeability layer, usually above an aquifer

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9
Q

definition of groundwater

A

the water contained in interconnected pores below the water table in an aquifer

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10
Q

definition of groundwater flow

A

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

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11
Q

different types of containment transportation

A
  • advection: due to groundwater
  • dispersion: due to irregular flow paths
  • diffusion: due to concentration gradient
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12
Q

What is advection (groundwater)

A
  • movement due to groundwater flow
  • contaminant (plume) moves with groundwater
  • similar to a rubber ducky flowing on a river - it moves at the same speed as the river
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13
Q

What is dispersion (groundwater)

A
  • due to irregular flow paths
  • micro, macro and mega scale dispersions
  • smaller pores = higher velocity
  • higher velocities = higher dispersion
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14
Q

what is diffusion (groundwater)

A
  • due to a concentration gradient
  • contaminant plume moves from high concentration to low concentration
  • important is low velocity souls (clays and bedrocks)
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15
Q

how are dispersion and diffusion similar?

A

they cause the contaminant (plume) to move beyond what would have been expected with just advection alone

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16
Q

what is sorption? (groundwater)

A
  • refers to the property of a solute (dissolved) to either attach to the surface of a solid (adsorption) and/or then penetrate the solid (absorption)
  • retardation causes the mean (average) contaminant velocity to be slower than the groundwater velocity
17
Q

definition of NAPLs

A

do not readily dissolve in water

18
Q

definition of LNAPLs

A

lighter than water

19
Q

definition of DNAPLs

A

denser than water

20
Q

definition of a non-aqueous phase liquids

A
  • blobs, blebs, globules, ganglion, form as NAPL migrates through the subsurface
  • immobile - not connected, do NOT flow
  • long term source of groundwater contamination
  • difficult to remove or remediate
21
Q

what are some groundwater remediation technologies?

A
  • fluid pumping technologies (groundwater pump and treat, SVE, air sparging)
  • mass destruction technologies (bioventing, oxidation, MNA)
  • enhanced fluid pumping technologies (heat, steam, high vacuum, surfactants)
  • enhanced bioremediation technologies (reactive zone, election donors)
22
Q

what happens during pump and treat?

A
  • uses advective treatment methods to remediate contaminated aquifer (P&T) and vadose (SVE) zones
  • advective methods rely on a fluid to move through the geology, have the contaminant transfer to the fluid, and then the fluid is brought above ground for treatment
  • water and air have typically been those fluids
23
Q

remediation technologies: pumping

A
  • NOT CONSIDERED A REMEDIATION TECHNOLOGY ANYMORE
  • used as a hydraulic containment technology
24
Q

how are groundwater plumes controlled?

A
  • hydrodynamic/hydraulic control
  • extracted groundwater must be treated prior to release
25
Q

what is a disadvantage of groundwater P&T

A
  • rebound (tailing)) occurs due to:
  • adsorption/desorption
  • back diffusion
  • NAPL ganglion
  • Heterogeneities
26
Q

what does SVE (soil vapour extraction) air flushing do for remediation?

A
  • unsaturated zone - soil remediation
27
Q

what does AS (air sparging) air flushing to for remediation?

A

saturated zone - plume remediation

28
Q

what do PRBs (permeable reactive barriers do for remediation?

A
  • passive interception and in situ treatment of dissolved contaminants in ground water
29
Q

what are the two different types of PRBs?

A
  • passive ( no moving parts, no pumping, no on-going additives)
  • semi-passive (some maintenance activities, additives, etc.)
30
Q

what is ISCO and how is it used as a remediation technology

A
  • Oxidation chemically converts hazardous contaminants to non-hazardous or less toxic compounds that are more stable, less mobile, and/or intert
  • oxidizing agents most commonly used are:
    (ozone, hydrogen peroxide, permanganate)
31
Q

when is ISCO used?

A
  • used to remediate groundwater and soil
  • applicable to a variety of soil types and grain sizes (silts and clays)
  • applicable to treat (VOCs (PCE, TCE, DCE, BTE)
  • rapid destruction/degradation of contaminants
  • produces no significant wastes
32
Q

what is MNA (remediation technology)

A
  • monitored natural attenuation
    “naturally-occurring processes in soil and groundwater environments that act WITHOUT HUMAN INTERVENTION to reduce the mass, toxicity, mobility, volume or concentration of contaminants in those media”
33
Q

when is MNA used?

A
  • used as remedial alternative must be fully protective of human health and the environment
  • typically used in conjunction with active remediation of source zones (removal, treatment or containment)
  • use of MNA must be supported through scientific line-of-evidence approach
  • monitoring must continue until remedial objectives are achieved
34
Q

what is a reactive zone?

A
  • created through injection of air, oxygen, O2 releasing compounds (ORC), etc
  • designed to treat or immobilize contaminants through biodegradation
35
Q

what is thermal remediation technology?

A
  • soil or groundwater
  • heat can destroy or volatilize contaminants
  • in-situ technology - uncertainties related to uniform heating/treatment due of subsurface variabilities
36
Q

what are the different types of thermal remediation technologies?

A
  • electrical resistivity heating
  • conduction heating
  • steam injection
37
Q

what is phytoremediation?

A
  • uses plants to address contaminant issues
  • objectives can be for (containment and control, removal and destruction)
38
Q

what is phytoremediation applicable for?

A
  • metals
  • pesticides
  • explosives
  • oils
  • solvents
  • can also prevent wind, rain, and groundwater from carrying contaminants off-site

Enviro 7060 (4 decks)

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