Innovative LNAPL Recovery Techniques

Innovative LNAPL Recovery Techniques

RTDFNON-AQUEOUS PHASE LIQUID (NAPL)

CLEANUP ALLIANCESan Antonio, TexasFebruary 7-8, 2006

RTDFNON-AQUEOUS PHASE LIQUID (NAPL)

CLEANUP ALLIANCESan Antonio, TexasFebruary 7-8, 2006

Presented by:Patrick E. Haas

P. E. Haas & Associates, LLChttp://www.phaas.net

Presented by:Patrick E. Haas

P. E. Haas & Associates, LLChttp://www.phaas.net

Problem:LNAPL on Soil

Problem:LNAPL on Soil

Problem:LNAPL in Soil

Problem:LNAPL in Soil

andin a well

andin a well

LNAPL CharacteristicsLNAPL CharacteristicsLNAPLs

Gasoline; jet fuels; diesels contain 200+ individual componentsComposition varies with source

LNAPLs can contain DNAPLsDNAPLS can contain LNAPLsAlways characterize NAPL composition; viscosity; density

Composition over time

LNAPLsGasoline; jet fuels; diesels contain 200+ individual componentsComposition varies with source

LNAPLs can contain DNAPLsDNAPLS can contain LNAPLsAlways characterize NAPL composition; viscosity; density

Composition over time

Vertical NAPL MigrationVertical NAPL MigrationZones of higher relative soil moisture or water saturation tend to inhibit downward migration of NAPL and cause spreading and poolingExamples:

Clay layers: Lower porosity and more perfectly wetted

Higher displacement pressures

Zones of higher relative soil moisture or water saturation tend to inhibit downward migration of NAPL and cause spreading and poolingExamples:

Clay layers: Lower porosity and more perfectly wetted

Higher displacement pressures

NAPL PhasesNAPL PhasesMobile - flows into wells - 30 - 80% saturation (pore space)Residual - small discontinuous globules or ganglia trapped in pore spaces

Can accumulate in wellsDissolved - solubilized in water in accordance with Rauolt’s lawVapor - volatilized into soil gas

Mobile - flows into wells - 30 - 80% saturation (pore space)Residual - small discontinuous globules or ganglia trapped in pore spaces

Can accumulate in wellsDissolved - solubilized in water in accordance with Rauolt’s lawVapor - volatilized into soil gas

Influence of Site Conditions on Maximum Plume Length

Influence of Site Conditions on Maximum Plume Length

Free Product?

YesNo

Free Product?

YesNo

11578

11578

170160170160

210200210200

330290330290

7,6001,7007,6001,700

Numberof sitesNumberof sites

25thQuartile

25thQuartile

50thQuartile(median)

50thQuartile(median)

75thQuartile

75thQuartile MaximumMaximum

Reference: University of Texas at Austin Bureau of Economic Geology, 1997

Reference: University of Texas at Austin Bureau of Economic Geology, 1997

Units: feetUnits: feet

Smearing: Before Water Table Fluctuation

Smearing: Before Water Table Fluctuation

NAPLNAPL

SolidSolid

WaterWater

Smearing: After Water Table Fluctuation

Smearing: After Water Table Fluctuation

AirAir NAPLNAPL

SolidSolid WaterWater

OilOil

Water Treatment DischargeWater Treatment Discharge

Horizontal Flow LinesHorizontal Flow Lines

Vacuum-enhancedVacuum-enhancedConventionalConventional

Air/Liquid Separator-Vacuum

Pump

Air/Liquid Separator-Vacuum

Pump

GroundwaterDepression PumpGroundwaterDepression Pump

Oil SkimmerPumpOil SkimmerPump

GroundwaterGroundwater

Air Flow in Vadose ZoneAir Flow in Vadose Zone

No Air FlowNo Air Flow

Flow Due toPressure InducedGradient

Flow Due toPressure InducedGradient

Oil/WaterSeparator

Oil/WaterSeparator

Oil/Water SeparatorOil/Water Separator

Air Treatmentor DischargeAir Treatmentor Discharge

Flow Due to Pressure InducedGradient

Flow Due to Pressure InducedGradient

Schedule of Activities: Free Product Recovery Pilot TestSchedule of Activities: Free Product Recovery Pilot Test

Pilot Test Activity ScheduleSite-specific Test Plan Day 14Test Plan Approval TBDMobilization Day 1-2Site Characterization Day 2-3

Baildown TestsSoil Gas Survey (Focused)Vapor Monitoring Point InstallationSoil SamplingSlug Test

Pilot Test Activity ScheduleSite-specific Test Plan Day 14Test Plan Approval TBDMobilization Day 1-2Site Characterization Day 2-3

Baildown TestsSoil Gas Survey (Focused)Vapor Monitoring Point InstallationSoil SamplingSlug Test

Schedule of Activities: Free Product Recovery Pilot Test

(cont)

Schedule of Activities: Free Product Recovery Pilot Test

(cont)

Pilot Test Activity ScheduleSystem Installation Day 2-3Test Start-up Day 4

Skimmer Test (2 days) Day 4-5Bioslurper Test (4 days) Day 6-9Air Permeability Test Day 6Skimmer and/or SVE Test (1 day) Day 10Drawdown Test (2 days) Day 11-12In Situ Respiration Test Day 11In Situ Respiration Test Day 12-14

Demobilization Day 14-15

Pilot Test Activity ScheduleSystem Installation Day 2-3Test Start-up Day 4

Skimmer Test (2 days) Day 4-5Bioslurper Test (4 days) Day 6-9Air Permeability Test Day 6Skimmer and/or SVE Test (1 day) Day 10Drawdown Test (2 days) Day 11-12In Situ Respiration Test Day 11In Situ Respiration Test Day 12-14

Demobilization Day 14-15

Baildown and Recovery Data

Baildown and Recovery DataBaildown Test Recovery Rates

SiteFuel Type

Original Product

Thickness (ft)

Final Product Thickness

(ft)Recovery

(%)Fuel

(gal/day)Water

(gal/day)TPH Vapor

(lb/day) *

Andrews AFB, MD

No. 2 Fuel Oil

2.32 2.01 87 78.5 1,820 6.5

Bolling AFB, D.C. (B. 18)

No. 2 Fuel Oil

4.44 3.52 79 59.85 2,751 0.009

Bolling AFB, D.C. (B.41)

Gasoline 0.34 0.32 94 1.55 0.81

1,286 1,052

470.1/---

Dover AFB, DE JP-4 3.73 3.77 101 43.2 2,844 ---/4.4

Edwards AFB, CA

JP-4 5.05 3.02 60 289.7 2,447

Havre AFS, MT (MW-7)

No.2 Fuel Oil

0.36 0.28 78 0.14 76 0.89

Havre AFS, MT (MW-F)

No.2 Fuel Oil

1.50 0.25 17 1.2 210 ---

Hickam AFB, HI Aviation Gasoline

3.98 3.95 99 90.9 2,313 132/ 0.030

Hill AFB, UT Fuel Oil 0.60 0.56 93 3.2 1,500 92

Fuel Recovery vs. TimeBuilding 18 – Well # HP-3Fuel Recovery vs. Time

Building 18 – Well # HP-3Fu

el R

ecov

ered

(gal

)

Time (hrs)

Fuel Recovery vs. TimeBuilding 41 – MW-3

Fuel Recovery vs. TimeBuilding 41 – MW-3

Fuel

Rec

over

ed (g

al)

Time (hrs)

Comparative Recovery DataComparative Recovery DataFinal Daily Fuel Recovery Rates (gal/day)

2-Day 4-Day 1-Day 2-Day BioslurperBase Skimmer Bioslurper Skimmer Drawdown Vapor

Location Site ID Test Test Test Test (lb/day TPH)Andrews AFB, MD B. 1845 6.6 64.5 0.71 (a) 6.5Bolling AFB, D.C. B. 18 15.25 59.9 8.2 31.2 0.009Bolling AFB, D.C. B. 41 0 0.48 NA 0.126 470.1Dover AFB, DE SS-27 27.9 43.2 9.4 (a) 612Edwards AFB, CA Site 24 13 55.8/ 73 (b) NA 54Griffiss AFB, NY PH-5 0 0.6 NA 0 91Havre AFS, MT Unit 70,

(MW-7) 0.19 0.073 0.012 0.01 0.89Havre AFS, MT Unit 63,

(MW-F) NA 0.62 NA NA NAHickam AFB, HI Area H 16.5 (b) (b) 470 132Hill AFB, UT OU-1 0.8 1.5 0.6 0.5 92

Soil Vapor Extraction via Internal Combustion EngineSoil Vapor Extraction via Internal Combustion Engine

MonitoringWell

Convertedto aSVEWell

MonitoringWell

Convertedto aSVEWell

Aboveground Knockout Tank Separator

Aboveground Knockout Tank Separator

Separator is modified vacuum tank that separates LNAPL from ground water/soil gasLNAPL accumulates in tank to a pre-set level and then drains to fuel storage tank under gravity

Separator is modified vacuum tank that separates LNAPL from ground water/soil gasLNAPL accumulates in tank to a pre-set level and then drains to fuel storage tank under gravity

Water

Fuel

VaporTo LRP

FromExtractionManifold

VacuumEqualization Tube

Three-WayValve

Drain

Drain

V

Knockout Tank SeparatorKnockout Tank SeparatorLiquid ring

pumpLiquid ring

pump

Dual Drop Tube Design Dual Drop Tube Design Water/Soil-Gas To

LiquidRingPumpFuel

LiquidTrap

Screen

Fuel

Fuel Extraction Tube

PVC Well

Ground Surface

Water/Soil-GasExtraction Tube

Soil-Gas

Water

Fuel IsolationSleeve Hydrophobic

Filter

Free-Phase Product

WaterTable

In-Well Separator: Dual Drop Tube

In-Well Separator: Dual Drop Tube

Shield prevents LNAPL from entering into drop tube while allowing groundwater to enter from below and soil vapor to enter from aboveLNAPL is extracted by a small-diameter tube located outside the shield

Shield prevents LNAPL from entering into drop tube while allowing groundwater to enter from below and soil vapor to enter from aboveLNAPL is extracted by a small-diameter tube located outside the shield

Dual Drop Tube Test: CSS Panama City

Dual Drop Tube Test: CSS Panama City

TPH Concentration (mg/L)(Percent Reduction from Conventional Configuration)Site Location

Conventional Dual Drop Tube Knockout TankShort-Term Test Sites (1—2 day)

NAS Fallon 1,800 7.5 (99%) 500 (72%)NCBC Davisville (EW-3) 1,040 450 (57%) NANCBC Davisville (EW-4) 3,050 16 (99%) NA

MCBH Kaneohe 1,715 60 (96%) 230 (86%)CSS Panama City 220 22 (90%) NA

ESTCP Short-Term Demonstrations (Preliminary)NAS Fallon 4,944 32.5 (99%) 1,600 (67%)Bolling AFB 588 1.2 (99%) 633 (0%)

NAWS China Lake

Results: Vacuum Pump Effluent Water

Results: Vacuum Pump Effluent Water

Results: Vacuum Pump Effluent Water

Results: Vacuum Pump Effluent Water

NCBC Davisville SamplesNCBC Davisville Samples

NAS Fallon - Short Term Test Influent and Effluent TPH

NAS Fallon - Short Term Test Influent and Effluent TPH

O/W Separator Effluent

0

200400

600800

1000

24 72 120

Operation Hours

TPH

(mg/

L)

O/W Separator Influent

02000400060008000

10000

24 72 120

Operation Hours

TPH

(mg/

L)

Conventional (Initial Knock out Tank Dual Drop Tube Conventional (Final)

NAS Fallon - Short Term Test Fuel and Groundwater Recovery

NAS Fallon - Short Term Test Fuel and Groundwater Recovery

Fuel Recovery

0

50

100

150

200

250

300

350

400

450

0 20 40 60 80 100 120 140

Time (hrs)

Fuel

Vol

ume

(gal

)

Traditional 1Knockout TankDual Drop TubeTraditional 2

Water Recovery

0

5,000

10,000

15,000

20,000

25,000

0 20 40 60 80 100 120 140

Time (hrs)

Wat

er V

olum

e (g

al)

Bolling AFB - Short Term Test Influent and Effluent TPH

Bolling AFB - Short Term Test Influent and Effluent TPH

O/W Separator Effluent

0

50

100

150

200

24 48 72

Operation Time

TPH

(mg/

L)

O/W Separator Influent

0100200300400500

600700800900

1000

24 48 72

Operation Hours

TPH

(mg/

L)

Conventional (Initial Knock out TankDual Drop Tube Conventional (Final)

Bolling AFB - Short Term Test Fuel and Groundwater Recovery Bolling AFB - Short Term Test

Fuel and Groundwater Recovery Fuel Recovery

0

2

4

6

8

10

12

0 10 20 30 40 50 60 70 80

Time (hrs)

Fuel

Vol

ume

(gal

)

Traditional 1Knockout Tank Dual Drop TubeTraditional 2

Water Recovery

0

1000

2000

3000

4000

5000

6000

0 10 20 30 40 50 60 70 80

Time (hrs)

Wat

er V

olum

e (g

al)

NAWS China Lake - Short Term Test Fuel and Groundwater Recovery

NAWS China Lake - Short Term Test Fuel and Groundwater Recovery

Fuel Recovery

0

20

40

60

80

100

120

140

160

0 10 20 30 40 50 60 70 80Time (hrs)

Fuel

Vol

ume

(gal

)

Traditional 1Knockout TankDual Drop Tube 1Dual Drop Tube 2

Water Recovery

0

2000

4000

6000

8000

10000

12000

14000

0 10 20 30 40 50 60 70 80

Time (hrs)

Wat

er V

olum

e (g

al)

Results: Off-GasResults: Off-Gas

Source: Hoeppel et. al.

TPH Concentration in the Off-Gas (ppmv),(Percent Reduction from Conventional Configuration)Site Location Conventional Dual Drop Tube Knockout Tank

NAS Fallon 3,210 900 (72%) 1,950 (39%)NCBC Davisville (EW-3) 675 620 (8%) NA

NCBC Davisville (EW-4) 870 145 (83%) NAESTCP Short-Term Demonstrations (Preliminary)

NAS Fallon 2,940 2,350 (20%) 3,960 (0%)Bolling AFB 160 100 (37%) 150 (6%)NAWS China Lake

72-hour Baildown Recovery Test Data

72-hour Baildown Recovery Test Data

In Situ RespirationIn Situ Respiration

He

O2

CO2

Date: 1/23/95 Site Name: Travis Air Force Base

Monitoring Point: MPC Depth of MP (ft): 5.5Date/Time (mm/dd/yr

hr:min)

Time (hr)

Oxygen (%)

Carbon Dioxide

(%)

Helium (%)

1/23/95 11:05 0.0 18.00 0.20 1.201/23/95 12:15 1.2 7.00 0.30 0.931/23/95 13:30 2.4 3.50 0.30 1.001/23/95 14:30 3.4 3.00 0.30 1.001/23/95 16:45 5.7 2.50 0.40 1.001/24/95 9:05 22.0 3.00 0.70 1.00

1/24/95 17:10 30.1 3.50 0.90 0.87

Regression Lines O2 CO2

Slope -4.2642 0.0264ko 0.071 %/min Intercept 15.3373 0.2288

4.264 %/hr Determination Coef. 0.8240 0.616482.895 102.340 %/day No. of Data Points 4 4

In Situ Respiration Test: Data Analysis

O2 Utilization Rate

02468

101214161820

0.0 10.0 20.0 30.0 40.0

Time (hr)O

2 and

CO

2 (%

)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

Hel

ium

(%)

Oxygen Conc.

O2 Regression

CO2 Conc.

CO2 Regression

Helium

BiodegradationRate

(mg/kg-day)

In Situ RespirationIn Situ Respiration

Bioventing PotentialBioventing PotentialFuel Storage Area G

Average biodegradation rate = 67.6 mg/kg-dayAssume:

Area of contamination = 750 m2

Contaminated soil is 2m thick1m3 of soil weighs 1440kg

67.6mg/kg-day x 1440kg/m3 x 750m2 x 2m = 146kg/day

Approximately 146 kg of hydrocarbons are biodegraded per

day

Fuel Storage Area GAverage biodegradation rate = 67.6 mg/kg-dayAssume:

Area of contamination = 750 m2

Contaminated soil is 2m thick1m3 of soil weighs 1440kg

67.6mg/kg-day x 1440kg/m3 x 750m2 x 2m = 146kg/day

Approximately 146 kg of hydrocarbons are biodegraded per

day

Laser-induced Hydrocarbon Fluorescence

Laser-induced Hydrocarbon Fluorescence

Fuel hydrocarbons at 26-31 ft bgs

Water table fluctuates

from 6-26 ft bgs

Historic low at 32 ft bgs

Fuel hydrocarbons at 26-31 ft bgs

Water table fluctuates

from 6-26 ft bgs

Historic low at 32 ft bgs

Laser-induced

fluorescence log

26 ft bgs

31 ft bgs

Smear Zone TreatmentSmear Zone Treatment

UST

GW Low-Low

GW Current

GW High-High

Product Recovery Well

Bioventing Well at GW

Current

Bioventing Well at GW Low-Low

Injected Air Flow

Lines

Injected Air Flow

Lines

LNAPL

Stable Benzene PlumeJune 1992 June 2001 October 2001

Stable Benzene PlumeJune 1992 June 2001 October 2001

Natural Removal RatesNatural Removal RatesStable Plume

Assuming ground water seepage velocities of 1 to 11 feet/day, a 450-footplume width and an average dissolved benzene concentration of 15 mg/Lacross a 20-foot vertical thickness, the mass removal rate of natural attenuation ranges from 940 – 10,400 lbs/year (140- 1,600 gallons/year)

Stable PlumeAssuming ground water seepage velocities of 1 to 11 feet/day, a 450-footplume width and an average dissolved benzene concentration of 15 mg/Lacross a 20-foot vertical thickness, the mass removal rate of natural attenuation ranges from 940 – 10,400 lbs/year (140- 1,600 gallons/year)

StrategyStrategySite characterization

Where is LNAPL in soil/aquifer matrix?Is LNAPL mobile?

Consecutive baildown recovery to assess mobilityShort-term low tech removal

Recovery PotentialBaildown, baildown, baildown?

What’s the risk?Composition – Kerosene or Benzene?NAPL and dissolved plume mobility –Stable, decreasing?

Site characterizationWhere is LNAPL in soil/aquifer matrix?Is LNAPL mobile?

Consecutive baildown recovery to assess mobilityShort-term low tech removal

Recovery PotentialBaildown, baildown, baildown?

What’s the risk?Composition – Kerosene or Benzene?NAPL and dissolved plume mobility –Stable, decreasing?

Strategy (cont)Strategy (cont)Remediation

During low ground water levelsIf mobile, consider liquid phase recover

Vacuum-enhanced?If volatile, consider SVEAlways consider biodegradation – Natural and bioventing

ClosureRisk-basedDevelop criteria for free product recovery to the maximum extent practical

RemediationDuring low ground water levelsIf mobile, consider liquid phase recover

Vacuum-enhanced?If volatile, consider SVEAlways consider biodegradation – Natural and bioventing

ClosureRisk-basedDevelop criteria for free product recovery to the maximum extent practical

Questions?