Comparison of Oxygen Comparison of Oxygen Delivery Methods Delivery Methods

((BiospargingBiosparging and iSOCand iSOC®®

Bioremediation Systems) for Bioremediation Systems) for in situ Vinyl Chloride in situ Vinyl Chloride

Treatment (Plume CutTreatment (Plume Cut--off)off)Jim F. Begley, MT Environmental Jim F. Begley, MT Environmental

Restoration, Plymouth/USA & Christine R. Restoration, Plymouth/USA & Christine R.

LeBlanc, LSP East Coast Engineering, IncLeBlanc, LSP East Coast Engineering, Inc

case study landfill sitecase study landfill sitematerial containing tetrachloroethene material containing tetrachloroethene (PCE) buried in 1986(PCE) buried in 1986PCE released to groundwaterPCE released to groundwaterhigh dissolved organic carbon in high dissolved organic carbon in groundwater from landfill leachate groundwater from landfill leachate reducing conditions resulted in incomplete reducing conditions resulted in incomplete reductive dechlorination of PCE to vinyl reductive dechlorination of PCE to vinyl chloride (VC)chloride (VC)

2002 groundwater assessment2002 groundwater assessment

detached plume of VC extending >2000 feetdetached plume of VC extending >2000 feet400+ feet wide and 30 feet thick400+ feet wide and 30 feet thicktop of the plume 50 feet below the water tabletop of the plume 50 feet below the water table2002 VC maximum concentration of 27 ppb, >13 2002 VC maximum concentration of 27 ppb, >13 times the applicable Massachusetts standard of times the applicable Massachusetts standard of 2 ppb2 ppb

hydrogeology and VC transporthydrogeology and VC transport

150 ft (50 m) of unconsolidated glacial deposits150 ft (50 m) of unconsolidated glacial depositsVC plume migrating at base of intermediate VC plume migrating at base of intermediate aquifer in fine sand with silt aquifer in fine sand with silt aquifer includes lenses of coarse sand, gravel, aquifer includes lenses of coarse sand, gravel, silt and clay silt and clay VC expected to migrate close to groundwater VC expected to migrate close to groundwater velocity (200 ft/yr)velocity (200 ft/yr)

remedial options evaluatedremedial options evaluated

monitored natural attenuation alonemonitored natural attenuation alone•• expected VC migration to water supply wellsexpected VC migration to water supply wells

addition of electron donor (vegetable oil) for addition of electron donor (vegetable oil) for further reductive further reductive dechlorinationdechlorination•• high concentration of sulfate (>100 mg/L) high concentration of sulfate (>100 mg/L) •• high DOC (electron donor) present (> 40 mg/L)high DOC (electron donor) present (> 40 mg/L)•• affects on water supply wells (affects on water supply wells (fefe, , mnmn, h, h22s)s)

selected remedial actionselected remedial action

groundwater treatment by direct aerobic groundwater treatment by direct aerobic biostimulation to promote degradation of vinyl biostimulation to promote degradation of vinyl chloride chloride

plume cutplume cut--off with multiple aerobic treatment off with multiple aerobic treatment fencesfences

BiospargingBiosparging & iSOC (2003, June/Aug)& iSOC (2003, June/Aug)

biospargingbiosparging

full fence

15 spargingwells

35 ft apart

monitoring well

45 ft down gradient

air injected at 2 to 4 cfm

iSOCiSOC®® Gas inFusionGas inFusionTechnologyTechnology

iSOC – in situ SubmergedOxygen Curtain

iSOCiSOC®® Gas inFusion ProcessGas inFusion Process

Direct aerobic treatment:Direct aerobic treatment:iSOC unit delivers iSOC unit delivers industrial grade pure industrial grade pure oxygen to treatment welloxygen to treatment wellSupersaturates well Supersaturates well (DO(DO—— 40 to 200 PPM 40 to 200 PPM depending on depending on groundwater depth)groundwater depth)Convection current fills Convection current fills well with uniform DOwell with uniform DODO disperses into DO disperses into groundwater stimulating groundwater stimulating bioremediationbioremediation

iSOC iSOC -- ComponentsComponents• 2“ PVC wells• filter screens 60 ft below watertable• oxygen delivery 15 cm³/min

iSOC iSOC –– well well configurationconfiguration

longitudinal cross sectionlongitudinal cross section

evaluation of oxygen evaluation of oxygen deliverydelivery

initial DO concentrations in treatment wells and initial DO concentrations in treatment wells and nearby monitoring wells were less than 0.3 mg/Lnearby monitoring wells were less than 0.3 mg/L

treatment well DO concentrations increased to treatment well DO concentrations increased to > 100 mg/L within 48 hours of system startup> 100 mg/L within 48 hours of system startup

associated with increase in ORP (20+ ft wide associated with increase in ORP (20+ ft wide area of influence at the treatment fence)area of influence at the treatment fence)

iSOC® Line-2 Monitoring Wells Oxidation Reduction Potential (ORP)

-700

-600

-500

-400

-300

-200

-100

0

100

200

Jul-03 Aug-03 Sep-03 Oct-03 Nov-03 Dec-03

Sample Date

OR

P (m

v) i-Ai-Bi-C

iSOC Line-2 Start-up

Downgradient performance Downgradient performance evaluation (startup evaluation (startup –– 6/04)6/04)

groundwater field screeninggroundwater field screening•• pH (pH units)pH (pH units)•• temperature (°C) temperature (°C) •• conductivity (um/ohms) conductivity (um/ohms) •• dissolved oxygen (DO) (mg/L) dissolved oxygen (DO) (mg/L) •• turbidity (NTU) turbidity (NTU) •• oxidationoxidation--reduction potential (ORP) reduction potential (ORP)

(mV)(mV)

Downgradient performance Downgradient performance evaluation (startup evaluation (startup –– 6/04)6/04)

groundwater sample laboratory analyses:groundwater sample laboratory analyses:•• volatile organic compounds (volatile organic compounds (VOCsVOCs) ) •• biological analyses (PLFA/biomass)biological analyses (PLFA/biomass)•• inorganic parameters: inorganic parameters:

total and dissolved irontotal and dissolved irontotal and dissolved manganesetotal and dissolved manganesealkalinity, nitrate, sulfate, sulfide, and chloridealkalinity, nitrate, sulfate, sulfide, and chloridedissolved gasses including carbon dioxidedissolved gasses including carbon dioxide

biobio--treatment zone treatment zone performance criteriaperformance criteria

increases in downgradient DO concentrationincreases in downgradient DO concentrationincreases in biomass increases in biomass decreases in VC concentrationdecreases in VC concentrationincreases in carbon dioxide concentration increases in carbon dioxide concentration •• indicates aerobic respirationindicates aerobic respiration

iSOCiSOC®® LineLine--1 performance at 1 performance at RBRB--35I35I

increased treatment zone DO 5 months postincreased treatment zone DO 5 months post--startup associated with ~2 fold decrease in VC startup associated with ~2 fold decrease in VC

drop in DO 6 months postdrop in DO 6 months post--startup associated startup associated with corresponding increase in VC with corresponding increase in VC

increase in COincrease in CO22 indicating aerobic respiration indicating aerobic respiration •• 276 mg/L March 03 276 mg/L March 03 •• 415 mg/L Dec 03415 mg/L Dec 03

Monitoring Well RB-35I Vinyl Chloride and Dissolved Oxygen Concentrations

0

1

2

3

4

5

6

7

8

Mar-03

Apr-03

May-03

Jun-03

Jul-03

Aug-03

Sep-03

Oct-03

Nov-03

Dec-03

Jan-04

Feb-04

Mar-04

Apr-04

May-04

Jun-04

Sample Date

Viny

l Chl

orid

e (u

g/L)

0.00

0.50

1.00

1.50

2.00

2.50

3.00

Dis

solv

ed O

xyge

n (m

g/L)

Vinyl ChlorideDissolved Oxygen

iSOC Line-1 Start-up

changechange in in biomassbiomass

Change in Biomass Following iSOC® Treatment System Start-up

1.00E+03

1.00E+04

1.00E+05

1.00E+06

MW-RB35I MW-RB35I

cells

/mL

wat

er

8/5/02

12/17/03

• Increase in biomass

• Increase in microbialdiversity•(by PLFA phospholipid fattyacid analysis)

iSOCiSOC®® LineLine--2 performance at 2 performance at RBRB--47D and RB47D and RB--47I47I

increase in DO with corresponding decrease in increase in DO with corresponding decrease in VC VC high concentration VC still entering the Linehigh concentration VC still entering the Line--2 2 treatment zonetreatment zone•• as measured at monitoring well ias measured at monitoring well i--AA

increase in COincrease in CO22 indicating aerobic respiration indicating aerobic respiration (RB(RB--47D)47D)•• 283 mg/L in March 03283 mg/L in March 03•• 367 mg/L in Dec 03367 mg/L in Dec 03

Monitoring Well RB-47D Vinyl Chloride and Dissolved Oxygen Concentrations

0

2

4

6

8

10

12

14

16

18

Mar-03

Apr-03

May-03

Jun-03

Jul-03

Aug-03

Sep-03

Oct-03

Nov-03

Dec-03

Jan-04

Feb-04

Mar-04

Apr-04

May-04

Jun-04

Sampling Date

Viny

l Chl

orid

e (u

g/L)

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Dis

solv

ed O

xyge

n (m

g/L)RB-47D Vinyl Chloride (VC)

Reference Well MW-i-A (VC)RB-47D Dissolved Oxygen

iSOC Line-2 Start-up

Monitoring Well RB-47I Vinyl Chloride and Dissolved Oxygen Concentrations

0.0

0.5

1.0

1.5

2.0

2.5

3.0M

ar-0

3A

pr-0

3M

ay-0

3Ju

n-03

Jul-0

3A

ug-0

3S

ep-0

3O

ct-0

3N

ov-0

3D

ec-0

3Ja

n-04

Feb-

04M

ar-0

4A

pr-0

4M

ay-0

4Ju

n-04

Sample Date

Viny

l Chl

orid

e (u

g/L)

0

0.2

0.4

0.6

0.8

1

1.2

1.4

Dis

solv

ed O

xyge

n (m

g/L)

Vinyl Chloride

DissolvedOxygen

iSOC Line-2 Start-up

VC not tested

VC "ND"

VC "ND"

biosparging performance at biosparging performance at RBRB--6060

increase in DO with corresponding increase in DO with corresponding decrease in VC decrease in VC increase in COincrease in CO22 indicating aerobic indicating aerobic respirationrespiration•• 60 mg/L in September 0360 mg/L in September 03•• 296 mg/L in Dec 03296 mg/L in Dec 03

Monitoring Well RB-60 Vinyl Chloride and Dissolved Oxygen Concentrations

0

1

2

3

4

5

6

Sep-03 Nov-03 Dec-03 Apr-04 Jun-04 Jul-04

Sample Date

Viny

l Chl

orid

e (u

g/L)

0

2

4

6

8

10

12

14

16

Dis

solv

ed O

xyge

n (m

g/L)

Vinyl Chloride

Dissolved Oxygen

System

start-up

biosparging problemsbiosparging problems

mechanical problems with compressor system mechanical problems with compressor system increase pressure in subsurface limiting air increase pressure in subsurface limiting air sparging flowsparging flowsignificant stratigraphic trapping of injected airsignificant stratigraphic trapping of injected airelectrical power would be necessary at remote electrical power would be necessary at remote locationslocations

May result in changes in plume migrationMay result in changes in plume migration

ConclusionsConclusions

field trial demonstrated the ability of both field trial demonstrated the ability of both the biosparging and iSOCthe biosparging and iSOC®® system to system to stimulate aerobic degradation of VC for stimulate aerobic degradation of VC for plume cutplume cut--offoff

the depth of the plume and site geology the depth of the plume and site geology lead to stratigraphic trapping of sparged lead to stratigraphic trapping of sparged air and potential gaps in plume treatmentair and potential gaps in plume treatment

ConclusionsConclusions

laboratory work was necessary to optimize laboratory work was necessary to optimize design design –– developed plan for nutrient and ethene developed plan for nutrient and ethene addition with iSOC to optimize performanceaddition with iSOC to optimize performance

design for full scale treatment includes: design for full scale treatment includes: •• closer spacing of iSOCcloser spacing of iSOC®® treatment wells (25 ft treatment wells (25 ft

apart) to maximize DO in the treatment zoneapart) to maximize DO in the treatment zone•• addition of nutrients to maximize treatment addition of nutrients to maximize treatment

efficiency efficiency

ladiesladies & & gentlemengentlemen::

thankthank youyou forfor youryour attentionattention!!