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Nonaqueous Nonaqueous Fluids in the Fluids in the

Vadose ZoneVadose ZoneA brief overview of a messy topicA brief overview of a messy topicA brief overview of a messy topicA brief overview of a messy topic

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Nonaqueous Fluids in the Vadose ZoneNonaqueous Fluids in the Vadose ZoneMuch vadose study aimed at contaminant transportMuch vadose study aimed at contaminant transport

One set of contaminates requires special treatment; One set of contaminates requires special treatment; those that are not miscible in water. those that are not miscible in water. referred to as Non-Aqueous Phase Liquids: NAPLs, referred to as Non-Aqueous Phase Liquids: NAPLs, low solubility in water. low solubility in water. non-polar compounds which remain as separate liquid phase (as non-polar compounds which remain as separate liquid phase (as

opposed to alcohol or latex). opposed to alcohol or latex).

Subdivided into those with density Subdivided into those with density lower than that of water (LNAPLs - Light; e.g., gasoline)lower than that of water (LNAPLs - Light; e.g., gasoline)denser than water (DNAPL - Dense, e.g., TCE, carbon tetrachloride).denser than water (DNAPL - Dense, e.g., TCE, carbon tetrachloride).

Much vadose study aimed at contaminant transportMuch vadose study aimed at contaminant transport

One set of contaminates requires special treatment; One set of contaminates requires special treatment; those that are not miscible in water. those that are not miscible in water. referred to as Non-Aqueous Phase Liquids: NAPLs, referred to as Non-Aqueous Phase Liquids: NAPLs, low solubility in water. low solubility in water. non-polar compounds which remain as separate liquid phase (as non-polar compounds which remain as separate liquid phase (as

opposed to alcohol or latex). opposed to alcohol or latex).

Subdivided into those with density Subdivided into those with density lower than that of water (LNAPLs - Light; e.g., gasoline)lower than that of water (LNAPLs - Light; e.g., gasoline)denser than water (DNAPL - Dense, e.g., TCE, carbon tetrachloride).denser than water (DNAPL - Dense, e.g., TCE, carbon tetrachloride).

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Numerous sources - LNAPLsNumerous sources - LNAPLsMost ubiquitous: Most ubiquitous:

leaking underground storage tanks (LUST’s)leaking underground storage tanks (LUST’s)

Gas stations:Gas stations:10% of single walled steel tanks leaked, 10% of single walled steel tanks leaked,

plumbing leaks in approximately 30% of these installations plumbing leaks in approximately 30% of these installations

lesson: don’t assume that the plume will be under the tank since most arise lesson: don’t assume that the plume will be under the tank since most arise from delivery system failure (Selker, 1991). from delivery system failure (Selker, 1991).

Note: Most commercial single walled UST’s have been Note: Most commercial single walled UST’s have been removed in the U. S. due to tightened regulation. removed in the U. S. due to tightened regulation.

Most ubiquitous: Most ubiquitous:

leaking underground storage tanks (LUST’s)leaking underground storage tanks (LUST’s)

Gas stations:Gas stations:10% of single walled steel tanks leaked, 10% of single walled steel tanks leaked,

plumbing leaks in approximately 30% of these installations plumbing leaks in approximately 30% of these installations

lesson: don’t assume that the plume will be under the tank since most arise lesson: don’t assume that the plume will be under the tank since most arise from delivery system failure (Selker, 1991). from delivery system failure (Selker, 1991).

Note: Most commercial single walled UST’s have been Note: Most commercial single walled UST’s have been removed in the U. S. due to tightened regulation. removed in the U. S. due to tightened regulation.

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Sources - LNAPLs cont.Sources - LNAPLs cont.Major source of LNAPLs: Major source of LNAPLs: household heating oil household heating oil

tanks. tanks.

Long overlooked, there are a vast number of leaking buried oil Long overlooked, there are a vast number of leaking buried oil tanks, (same proportions as old gas station tanks)tanks, (same proportions as old gas station tanks)

Household leaks rarely noticed until catastrophic failure, since Household leaks rarely noticed until catastrophic failure, since there are no records of consumption. there are no records of consumption.

The lower volatility of heating oil also limits the observation of The lower volatility of heating oil also limits the observation of leaks through vapor transport into basements etc.leaks through vapor transport into basements etc.

Major source of LNAPLs: Major source of LNAPLs: household heating oil household heating oil tanks. tanks.

Long overlooked, there are a vast number of leaking buried oil Long overlooked, there are a vast number of leaking buried oil tanks, (same proportions as old gas station tanks)tanks, (same proportions as old gas station tanks)

Household leaks rarely noticed until catastrophic failure, since Household leaks rarely noticed until catastrophic failure, since there are no records of consumption. there are no records of consumption.

The lower volatility of heating oil also limits the observation of The lower volatility of heating oil also limits the observation of leaks through vapor transport into basements etc.leaks through vapor transport into basements etc.

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Sources - DNAPLsSources - DNAPLsDNAPLs in the environment typically arise from disposal of cleaning DNAPLs in the environment typically arise from disposal of cleaning

compounds.compounds.

Whereas LNAPLs are most commonly observed at points of Whereas LNAPLs are most commonly observed at points of delivery, DNAPLs are found at points of delivery, use, and disposal.delivery, DNAPLs are found at points of delivery, use, and disposal.

““Dry wells” and other ad hoc disposal sites represent a major portion Dry wells” and other ad hoc disposal sites represent a major portion of plume generators, often near the point of use, or at waste of plume generators, often near the point of use, or at waste disposal sites. disposal sites.

Spills are typically of smaller volume than LNAPLs, but more serious Spills are typically of smaller volume than LNAPLs, but more serious due to higher toxicity and bulk penetration of aquifersdue to higher toxicity and bulk penetration of aquifers

DNAPLs in the environment typically arise from disposal of cleaning DNAPLs in the environment typically arise from disposal of cleaning compounds.compounds.

Whereas LNAPLs are most commonly observed at points of Whereas LNAPLs are most commonly observed at points of delivery, DNAPLs are found at points of delivery, use, and disposal.delivery, DNAPLs are found at points of delivery, use, and disposal.

““Dry wells” and other ad hoc disposal sites represent a major portion Dry wells” and other ad hoc disposal sites represent a major portion of plume generators, often near the point of use, or at waste of plume generators, often near the point of use, or at waste disposal sites. disposal sites.

Spills are typically of smaller volume than LNAPLs, but more serious Spills are typically of smaller volume than LNAPLs, but more serious due to higher toxicity and bulk penetration of aquifersdue to higher toxicity and bulk penetration of aquifers

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A typical sceneA typical scene

UST

Floating "Free Product"

Residual Saturation (1-5%)

Hydraulic Gradient

Aqueous Phase Plume

Vapor Phase Plume

Capillary Fringe

Source: Leaking Joint

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The Components of a PlumeThe Components of a Plume

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The Anatomy of a NAPL SpillThe Anatomy of a NAPL SpillPrediction of NAPL movement complicated by physical and Prediction of NAPL movement complicated by physical and

chemical processes making quantitative prediction generally chemical processes making quantitative prediction generally impossible for field spills (Osborne and Sykes, 1986; Cary et impossible for field spills (Osborne and Sykes, 1986; Cary et al., 1989b; Essaid et al., 1993). al., 1989b; Essaid et al., 1993).

Most productive to understand the qualitative characteristics Most productive to understand the qualitative characteristics movement, rather than spend inordinate energy on movement, rather than spend inordinate energy on quantitative prediction of NAPL disposition.quantitative prediction of NAPL disposition.

A key point: residual saturation can account for a large A key point: residual saturation can account for a large fraction of a spill. fraction of a spill.

Prediction of NAPL movement complicated by physical and Prediction of NAPL movement complicated by physical and chemical processes making quantitative prediction generally chemical processes making quantitative prediction generally impossible for field spills (Osborne and Sykes, 1986; Cary et impossible for field spills (Osborne and Sykes, 1986; Cary et al., 1989b; Essaid et al., 1993). al., 1989b; Essaid et al., 1993).

Most productive to understand the qualitative characteristics Most productive to understand the qualitative characteristics movement, rather than spend inordinate energy on movement, rather than spend inordinate energy on quantitative prediction of NAPL disposition.quantitative prediction of NAPL disposition.

A key point: residual saturation can account for a large A key point: residual saturation can account for a large fraction of a spill. fraction of a spill.

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Influence of WatertableInfluence of Watertable

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PermeabilityPermeability

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Residual NAPLResidual NAPLNAPLs tend to form small droplets (a.k.a. ganglia) in NAPLs tend to form small droplets (a.k.a. ganglia) in

the unsaturated zonethe unsaturated zone

On the order of 5% of the volume of the region On the order of 5% of the volume of the region which experienced NAPL transport will remain which experienced NAPL transport will remain NAPL filled with residual product (Cary et al., 1989c)NAPL filled with residual product (Cary et al., 1989c)

This important for planning in soil clean up, as well This important for planning in soil clean up, as well as understanding how much of the product may as understanding how much of the product may have reached the upper aquifer.have reached the upper aquifer.

NAPLs tend to form small droplets (a.k.a. ganglia) in NAPLs tend to form small droplets (a.k.a. ganglia) in the unsaturated zonethe unsaturated zone

On the order of 5% of the volume of the region On the order of 5% of the volume of the region which experienced NAPL transport will remain which experienced NAPL transport will remain NAPL filled with residual product (Cary et al., 1989c)NAPL filled with residual product (Cary et al., 1989c)

This important for planning in soil clean up, as well This important for planning in soil clean up, as well as understanding how much of the product may as understanding how much of the product may have reached the upper aquifer.have reached the upper aquifer.

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Example of residualExample of residualA spill of 10,000 l of product 10 m above an unconfined aquifer. A spill of 10,000 l of product 10 m above an unconfined aquifer. Assuming that the NAPL wetted area of 4 m by 4 m and a residual Assuming that the NAPL wetted area of 4 m by 4 m and a residual saturation of 5%, how much of this original spill makes it to the saturation of 5%, how much of this original spill makes it to the water table in liquid form?water table in liquid form?

SolutionSolution::

The residual volume in the vadose zone is: The residual volume in the vadose zone is:

10 m x 4 m x 4 m x 5%10 m x 4 m x 4 m x 5% = 8 m= 8 m33

= 8,000 l= 8,000 l

therefore about 2,000 liters (20%) makes it to the water table.therefore about 2,000 liters (20%) makes it to the water table.

Obviously our uncertainty exceeds +/- 20%, so we really have little Obviously our uncertainty exceeds +/- 20%, so we really have little idea of how much made it to the water table, but should assume idea of how much made it to the water table, but should assume that a significant amount did.that a significant amount did.

A spill of 10,000 l of product 10 m above an unconfined aquifer. A spill of 10,000 l of product 10 m above an unconfined aquifer. Assuming that the NAPL wetted area of 4 m by 4 m and a residual Assuming that the NAPL wetted area of 4 m by 4 m and a residual saturation of 5%, how much of this original spill makes it to the saturation of 5%, how much of this original spill makes it to the water table in liquid form?water table in liquid form?

SolutionSolution::

The residual volume in the vadose zone is: The residual volume in the vadose zone is:

10 m x 4 m x 4 m x 5%10 m x 4 m x 4 m x 5% = 8 m= 8 m33

= 8,000 l= 8,000 l

therefore about 2,000 liters (20%) makes it to the water table.therefore about 2,000 liters (20%) makes it to the water table.

Obviously our uncertainty exceeds +/- 20%, so we really have little Obviously our uncertainty exceeds +/- 20%, so we really have little idea of how much made it to the water table, but should assume idea of how much made it to the water table, but should assume that a significant amount did.that a significant amount did.

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Geologic EffectsGeologic EffectsGeologic configuration key to disposition of NAPLs Geologic configuration key to disposition of NAPLs LNAPLs: the vadose zone is of primary importance, since LNAPLs: the vadose zone is of primary importance, since

the bulk liquid does not penetrate the saturated zone, the bulk liquid does not penetrate the saturated zone, DNAPLs: the structure in both saturated and unsaturated DNAPLs: the structure in both saturated and unsaturated

regions will have a major impact on disposition. regions will have a major impact on disposition. Main issue: layers between media of different texture. In Main issue: layers between media of different texture. In

particular, horizontal bedding features will cause the plume particular, horizontal bedding features will cause the plume to spread laterally with a dominant down-dip movement to spread laterally with a dominant down-dip movement (Schroth et al., 1997).(Schroth et al., 1997).

Geologic configuration key to disposition of NAPLs Geologic configuration key to disposition of NAPLs LNAPLs: the vadose zone is of primary importance, since LNAPLs: the vadose zone is of primary importance, since

the bulk liquid does not penetrate the saturated zone, the bulk liquid does not penetrate the saturated zone, DNAPLs: the structure in both saturated and unsaturated DNAPLs: the structure in both saturated and unsaturated

regions will have a major impact on disposition. regions will have a major impact on disposition. Main issue: layers between media of different texture. In Main issue: layers between media of different texture. In

particular, horizontal bedding features will cause the plume particular, horizontal bedding features will cause the plume to spread laterally with a dominant down-dip movement to spread laterally with a dominant down-dip movement (Schroth et al., 1997).(Schroth et al., 1997).

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Geologic EffectsGeologic Effects

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Real Data…(Kueper et al., 1993)Real Data…(Kueper et al., 1993)

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Rate of introduction highly influentialRate of introduction highly influentialRapid spillsRapid spillsrequire broader areas to carry the flowrequire broader areas to carry the flowlarger residual saturation in the unsaturated zonelarger residual saturation in the unsaturated zoneless free product on aquifersless free product on aquifersless susceptible to extreme lateral flow due to textural interfaces.less susceptible to extreme lateral flow due to textural interfaces.

Slow leaksSlow leaksmore susceptible to lateral diversion along textural interfacesmore susceptible to lateral diversion along textural interfaceslikely follow more isolated paths of flowlikely follow more isolated paths of flowSlow leaks tend to contaminate a larger area, while still delivering a Slow leaks tend to contaminate a larger area, while still delivering a

greater fraction of the product to the aquifergreater fraction of the product to the aquifer

Rapid spillsRapid spillsrequire broader areas to carry the flowrequire broader areas to carry the flowlarger residual saturation in the unsaturated zonelarger residual saturation in the unsaturated zoneless free product on aquifersless free product on aquifersless susceptible to extreme lateral flow due to textural interfaces.less susceptible to extreme lateral flow due to textural interfaces.

Slow leaksSlow leaksmore susceptible to lateral diversion along textural interfacesmore susceptible to lateral diversion along textural interfaceslikely follow more isolated paths of flowlikely follow more isolated paths of flowSlow leaks tend to contaminate a larger area, while still delivering a Slow leaks tend to contaminate a larger area, while still delivering a

greater fraction of the product to the aquifergreater fraction of the product to the aquifer

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Rate of spill effectsRate of spill effects

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Real Data (Kueper et al., 1992)Real Data (Kueper et al., 1992)

The upper plot is fromThe upper plot is from

an instantaneous an instantaneous

release, while the lowerrelease, while the lower

plot resulted from aplot resulted from a

slow injection, whichslow injection, which

penetrated further, andpenetrated further, and

spread more widelyspread more widely

The upper plot is fromThe upper plot is from

an instantaneous an instantaneous

release, while the lowerrelease, while the lower

plot resulted from aplot resulted from a

slow injection, whichslow injection, which

penetrated further, andpenetrated further, and

spread more widelyspread more widely

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LNAPLs vs DNAPLsLNAPLs vs DNAPLsIn the vadose zone DNAPLs and LNAPLs behave quite similarly if saturation not In the vadose zone DNAPLs and LNAPLs behave quite similarly if saturation not

encountered. encountered. Logical since the only distinction we have made between these is their relative Logical since the only distinction we have made between these is their relative

density in comparison to water. density in comparison to water. there are no buoyancy effects in vadose zonethere are no buoyancy effects in vadose zonethe physics of flow is essentially the samethe physics of flow is essentially the same

Once saturated regions encountered, migration differs dramatically for LNAPLs Once saturated regions encountered, migration differs dramatically for LNAPLs and DNAPLs. and DNAPLs. LNAPLs travel in direction of the slope of the LNAPLs travel in direction of the slope of the water tablewater tableDNAPLs travel in direction of slope of the DNAPLs travel in direction of slope of the lower boundarylower boundary DNAPLs move through aquifers in web like networks of pores (e.g., Held and DNAPLs move through aquifers in web like networks of pores (e.g., Held and

Illangasekare, 1995). Illangasekare, 1995). this reduces residual saturation, thus increasing the free product available to this reduces residual saturation, thus increasing the free product available to

spread through the aquifer.spread through the aquifer.

In the vadose zone DNAPLs and LNAPLs behave quite similarly if saturation not In the vadose zone DNAPLs and LNAPLs behave quite similarly if saturation not encountered. encountered. Logical since the only distinction we have made between these is their relative Logical since the only distinction we have made between these is their relative

density in comparison to water. density in comparison to water. there are no buoyancy effects in vadose zonethere are no buoyancy effects in vadose zonethe physics of flow is essentially the samethe physics of flow is essentially the same

Once saturated regions encountered, migration differs dramatically for LNAPLs Once saturated regions encountered, migration differs dramatically for LNAPLs and DNAPLs. and DNAPLs. LNAPLs travel in direction of the slope of the LNAPLs travel in direction of the slope of the water tablewater tableDNAPLs travel in direction of slope of the DNAPLs travel in direction of slope of the lower boundarylower boundary DNAPLs move through aquifers in web like networks of pores (e.g., Held and DNAPLs move through aquifers in web like networks of pores (e.g., Held and

Illangasekare, 1995). Illangasekare, 1995). this reduces residual saturation, thus increasing the free product available to this reduces residual saturation, thus increasing the free product available to

spread through the aquifer.spread through the aquifer.

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LNAPLs vs DNAPLs LNAPLs vs DNAPLs

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DNAPL MigrationDNAPL Migration

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DNAPL MigrationDNAPL Migration

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DNAPLs in WellsDNAPLs in Wells

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DNAPLs and wells...DNAPLs and wells...

In the case of DNAPLs, wells present a In the case of DNAPLs, wells present a more serious threat. more serious threat. If a well screen crosses an aquitard, the well If a well screen crosses an aquitard, the well

itself can become a pathway for transport, with itself can become a pathway for transport, with a DNAPL draining off the aquitard, into the a DNAPL draining off the aquitard, into the well, and out the well in the lower aquifer. well, and out the well in the lower aquifer.

For LNAPLs, by creating a cone of depression For LNAPLs, by creating a cone of depression about a well you may facilitate removal of the about a well you may facilitate removal of the contaminant which will then flow to the wellcontaminant which will then flow to the well

In the case of DNAPLs, wells present a In the case of DNAPLs, wells present a more serious threat. more serious threat. If a well screen crosses an aquitard, the well If a well screen crosses an aquitard, the well

itself can become a pathway for transport, with itself can become a pathway for transport, with a DNAPL draining off the aquitard, into the a DNAPL draining off the aquitard, into the well, and out the well in the lower aquifer. well, and out the well in the lower aquifer.

For LNAPLs, by creating a cone of depression For LNAPLs, by creating a cone of depression about a well you may facilitate removal of the about a well you may facilitate removal of the contaminant which will then flow to the wellcontaminant which will then flow to the well

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Observing LNAPLs in WellsObserving LNAPLs in WellsOften the first indication of NAPL contamination is the Often the first indication of NAPL contamination is the

observation of the product in a wellobservation of the product in a well

The extent of a plume at a site is often then delineated by The extent of a plume at a site is often then delineated by installing additional wells on the siteinstalling additional wells on the site

The extent of contamination is then delineated by obtaining The extent of contamination is then delineated by obtaining core sample sand observing the depth of "free product" in the core sample sand observing the depth of "free product" in the wellswells

BE CAREFUL: The depth observed in wells is not the free BE CAREFUL: The depth observed in wells is not the free product depth on the aquiferproduct depth on the aquifer

Often the first indication of NAPL contamination is the Often the first indication of NAPL contamination is the observation of the product in a wellobservation of the product in a well

The extent of a plume at a site is often then delineated by The extent of a plume at a site is often then delineated by installing additional wells on the siteinstalling additional wells on the site

The extent of contamination is then delineated by obtaining The extent of contamination is then delineated by obtaining core sample sand observing the depth of "free product" in the core sample sand observing the depth of "free product" in the wellswells

BE CAREFUL: The depth observed in wells is not the free BE CAREFUL: The depth observed in wells is not the free product depth on the aquiferproduct depth on the aquifer

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Geometry of LNAPLs in wellsGeometry of LNAPLs in wells

Typical observation well at an LNAPL spill site where HTypical observation well at an LNAPL spill site where Hoiloil is the is the

“True” depth of free product, H“True” depth of free product, Hcapcap is the thickness of the capillary is the thickness of the capillary

fringe, Hfringe, Happapp is the “apparent” depth of free product, and H is the “apparent” depth of free product, and Hdd the the

depression of the water surface in the welldepression of the water surface in the well

Typical observation well at an LNAPL spill site where HTypical observation well at an LNAPL spill site where Hoiloil is the is the

“True” depth of free product, H“True” depth of free product, Hcapcap is the thickness of the capillary is the thickness of the capillary

fringe, Hfringe, Happapp is the “apparent” depth of free product, and H is the “apparent” depth of free product, and Hdd the the

depression of the water surface in the welldepression of the water surface in the well

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Calculating some depthsCalculating some depthsAt the oil-water interface in At the oil-water interface in the well, the total head is the well, the total head is

the total head at all points in the total head at all points in the aquifer is constant the aquifer is constant (assuming that we are not (assuming that we are not pumping from the well), so pumping from the well), so head at the interface is also head at the interface is also given bygiven by

Equating these we obtainEquating these we obtain

At the oil-water interface in At the oil-water interface in the well, the total head is the well, the total head is

the total head at all points in the total head at all points in the aquifer is constant the aquifer is constant (assuming that we are not (assuming that we are not pumping from the well), so pumping from the well), so head at the interface is also head at the interface is also given bygiven by

Equating these we obtainEquating these we obtain

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Finishing the algebraFinishing the algebraFrom the set-up geometryFrom the set-up geometry

solving for Hsolving for Hdd

We may rewrite this using the We may rewrite this using the geometric result asgeometric result as

Solving for HSolving for Hoil oil

NOTE:NOTE: denominator denominator small!small!

From the set-up geometryFrom the set-up geometry

solving for Hsolving for Hdd

We may rewrite this using the We may rewrite this using the geometric result asgeometric result as

Solving for HSolving for Hoil oil

NOTE:NOTE: denominator denominator small!small!

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ExampleExampleFor typical NAPLs For typical NAPLs oiloil//ww) is about 0.8. Taking H) is about 0.8. Taking Hcapcap to be 50 cm (typical for a to be 50 cm (typical for a

silt loam texture), and assuming the true depth of free product to be 2 cm, we silt loam texture), and assuming the true depth of free product to be 2 cm, we can use [2.162] to calculate the “apparent depth” of NAPL in the wellcan use [2.162] to calculate the “apparent depth” of NAPL in the well

almost 3 m of “free product” in the well! almost 3 m of “free product” in the well!

Very sensitive to:Very sensitive to:

the height of the capillary fringethe height of the capillary fringe the density contrast of the liquidsthe density contrast of the liquidsDensity contrast easy, but the height of the effective capillary fringe Density contrast easy, but the height of the effective capillary fringe

is difficult to measure. is difficult to measure.

For typical NAPLs For typical NAPLs oiloil//ww) is about 0.8. Taking H) is about 0.8. Taking Hcapcap to be 50 cm (typical for a to be 50 cm (typical for a

silt loam texture), and assuming the true depth of free product to be 2 cm, we silt loam texture), and assuming the true depth of free product to be 2 cm, we can use [2.162] to calculate the “apparent depth” of NAPL in the wellcan use [2.162] to calculate the “apparent depth” of NAPL in the well

almost 3 m of “free product” in the well! almost 3 m of “free product” in the well!

Very sensitive to:Very sensitive to:

the height of the capillary fringethe height of the capillary fringe the density contrast of the liquidsthe density contrast of the liquidsDensity contrast easy, but the height of the effective capillary fringe Density contrast easy, but the height of the effective capillary fringe

is difficult to measure. is difficult to measure.

Happ = 2 cm + 50 cm 1 - 0.8

= 520.2

= 260 cm

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Data from experimentsData from experimentsObservedObserved ActualActual

in wellin well free productfree product

ObservedObserved ActualActual

in wellin well free productfree product

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Movement and RetentionMovement and Retention

1. Initial emplacement1. Initial emplacement

2. Soluable losses2. Soluable losses

3. Aging3. Aging

1. Initial emplacement1. Initial emplacement

2. Soluable losses2. Soluable losses

3. Aging3. Aging

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Initial EmplacementInitial EmplacementWe have already discussed the over-riding We have already discussed the over-riding issues. A few more remarks:issues. A few more remarks:Movement strongly effected by surface tensionMovement strongly effected by surface tensionSurface tension is a function of TIME!! Surface tension is a function of TIME!!

changes rapidly in first hours as interfaces come to local changes rapidly in first hours as interfaces come to local equilibrium with fluids (on the order of 30% change)equilibrium with fluids (on the order of 30% change)

changes slowly as the fluids age through partioning losseschanges slowly as the fluids age through partioning losseschanges slowly as local microbes put out surfactantschanges slowly as local microbes put out surfactants

Movement typically unstable. No codes handle this.Movement typically unstable. No codes handle this.Any predictions must be field validatedAny predictions must be field validated

We have already discussed the over-riding We have already discussed the over-riding issues. A few more remarks:issues. A few more remarks:Movement strongly effected by surface tensionMovement strongly effected by surface tensionSurface tension is a function of TIME!! Surface tension is a function of TIME!!

changes rapidly in first hours as interfaces come to local changes rapidly in first hours as interfaces come to local equilibrium with fluids (on the order of 30% change)equilibrium with fluids (on the order of 30% change)

changes slowly as the fluids age through partioning losseschanges slowly as the fluids age through partioning losseschanges slowly as local microbes put out surfactantschanges slowly as local microbes put out surfactants

Movement typically unstable. No codes handle this.Movement typically unstable. No codes handle this.Any predictions must be field validatedAny predictions must be field validated

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Textural Interfaces: Multiphase flowTextural Interfaces: Multiphase flowLet’s look at three oil spill casesLet’s look at three oil spill casesno waterno water

flowing flowing

little water little water flowingflowing

lots of water lots of water flowingflowing

Let’s look at three oil spill casesLet’s look at three oil spill casesno waterno water

flowing flowing

little water little water flowingflowing

lots of water lots of water flowingflowing

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Soluble losses and agingSoluble losses and agingMany NAPLs are moderately soluable in waterMany NAPLs are moderately soluable in waterSince there is much more water than NAPL, this Since there is much more water than NAPL, this

leads to significant losses (plume)leads to significant losses (plume)Many NAPLs are mixtures of hydrocarbons etc. Many NAPLs are mixtures of hydrocarbons etc.

(e.g., gasoline has 10’s of major components)(e.g., gasoline has 10’s of major components)Each of the constituents will partition into the Each of the constituents will partition into the

water and gas phases according to its own water and gas phases according to its own solubilitysolubility

As the NAPL sits, it changes it makeup becoming As the NAPL sits, it changes it makeup becoming less soluable/volatile (aging)less soluable/volatile (aging)

Many NAPLs are moderately soluable in waterMany NAPLs are moderately soluable in waterSince there is much more water than NAPL, this Since there is much more water than NAPL, this

leads to significant losses (plume)leads to significant losses (plume)Many NAPLs are mixtures of hydrocarbons etc. Many NAPLs are mixtures of hydrocarbons etc.

(e.g., gasoline has 10’s of major components)(e.g., gasoline has 10’s of major components)Each of the constituents will partition into the Each of the constituents will partition into the

water and gas phases according to its own water and gas phases according to its own solubilitysolubility

As the NAPL sits, it changes it makeup becoming As the NAPL sits, it changes it makeup becoming less soluable/volatile (aging)less soluable/volatile (aging)

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Partitioning of Common NAPLsPartitioning of Common NAPLs

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Skimming Free ProductSkimming Free Product

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Summary on NAPLsSummary on NAPLsUnderstanding the physics and chemistry of Understanding the physics and chemistry of NAPL movement is helpfulNAPL movement is helpful

Don’t expect to accurately predict dispositionDon’t expect to accurately predict disposition

This has only been a brief overview. Lots of This has only been a brief overview. Lots of very good work on these issuesvery good work on these issues

Understanding the physics and chemistry of Understanding the physics and chemistry of NAPL movement is helpfulNAPL movement is helpful

Don’t expect to accurately predict dispositionDon’t expect to accurately predict disposition

This has only been a brief overview. Lots of This has only been a brief overview. Lots of very good work on these issuesvery good work on these issues