CSM-2014 Air Sparge Implementation - pdf

2014 – Contaminated Site Management (CSM-2014) Sustainable Remediation & Management of Soil, Sediment and Water


FULL - SCALE IMPLEMENTATION OF A PULSED

AIR SPARGE AND SVE SYSTEM FOR

TREATMENT OF VOCS, SVOCS, AND ARSENIC

Presented By:

Nadira Najib, Omer Uppal, Matthew

Ambrusch, Annie Lee, Jessica Friscia,

Kawalpreet Kaur, Stewart Abrams, P.E.,

Steve Ciambruschini, LEP


Presentation Outline • Intro to Air Sparging

• Former Lagoon Area [FLA], Montville NJ

• Background

• Why Air Sparging?

• Pilot Testing Activities

• Modeling Results/Considerations

• Final Design

• System Implementation


Zone of Air Distribution Air Channeling

What is Air Sparging? An in-situ remedial technology that reduces concentrations of

VOCs dissolved in groundwater or adsorbed to soils through

volatilization and bioremediation by the injection of air.


What is Air Sparging?

http://www.clu-in.org/download/techfocus/air-sparging/ABR09-4-AS.pdf


How Air Sparging Works?

• In-situ air stripping of dissolved VOCs in groundwater:

• Henry’s Law Constant

• Vapor Pressure

• Volatilization of trapped and adsorbed VOCs in soils:

• Soil Organic Carbon-Water Partitioning Coefficient

• Precipitation of metals in groundwater:

• Oxidizing environment

• Biosparging versus Air Sparging

• Aerobic biodegradation

eeg.geoscienceworld.org

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&uact=8&docid=fWY9PLrjr6tUEM&tbnid=lQFdWmyjcNbVLM:&ved=0CAUQjB0&url=http://eeg.geoscienceworld.org/content/9/1/71/F1.expansion.html&ei=Tu8lU6vPF8T_rQe7kYD4AQ&psig=AFQjCNGCyPP93zkQjK8xfQbDuTsbRwbB-w&ust=1395081415204938


Design Considerations

• Radius of Influence

• Target Interval

• Subsurface Conditions

• Intrinsic Permeability

• Confining Layers

• Fracture Pressure

• Contaminants of Concern

• Air flow rate and pressure at wellhead


Importance of Pilot Testing/Modeling Pilot Testing : An opportunity to test, measure, and collect site specific subsurface characteristics, including permeability and pressure/vacuum flow relationships, etc.

0

0.5

1

1.5

2

2.5

3

0 50 100

30 SCFM

40 SCFM

50 SCFM

Design Flow

Distance from Vapor

Vac

uu

m (

inH

2O

)

Modeling : Evaluate and engineer the most effective remedial design, taking

into consideration ROI, air flow rate, and pressure/vacuum.


Former Lagoon Area [FLA]

Montville, New Jersey


Site Background

• Former manufacturing facility with active

lagoon operations through 1954 and

backfilled between 1967 and 1970

• Benzene, VOCs, SVOCs, and heavy metals

(i.e., Arsenic) in soil and groundwater

• Former biosparge system operation from

2002 through 2012 - Model predicted

cleanup time frames >> 50 years


Site Layout

GW Flow Direction DIAGNOSTIC TESTING

FOCUSED AREAS


FLA – Background • Former textile mills/pharmaceuticals manufacturing plant

• Primary COCs :

• Benzene up to 20,900 ug/L

• Phenol up to 12,800 ug/L

• Arsenic up to 31.2 ug/L

• Geology

• Fill layer

• Alluvium layer

• Glacial Till layer

• Hydrogeology • Groundwater table ranges approximately 1.5 to 6.5 feet bgs


FLA – Why Air Sparging? • Past Remediation Efforts:

• Biosparge

• Excavation

• Primary COC

• Size of Potential Treatment Area

• Source/Concentrations


FLA-Pilot Testing Activities

• Testing Methods

• SVE/Point Permeability

• Air Sparge/Helium Tracer

• Biorespiration

• Parameters of Interest

• Air flow rate

• Pressure

• Vacuum


FLA – Pilot Testing Activities


FLA – Pneumatic Modeling Results/Considerations MDFIT – Computer Pneumatic Modeling Program

5.5 scfm

8.5 scfm

13 scfm

0

20

40

60

80

100

120

140

160

180

0 2 4 6 8 10 12 14 16

Vac

uu

m (

in H

2O

)

Distance from Test Well (feet)

Permeability Calibration for Engineered Fill Material

5 SCFM

7.5 SCFM

10 SCFM

12.5 SCFM

MeasuredVacuum

Calibrated Permeability Kr = Kz = 3.50E-08 Kc = 1.83E-06

5.4 scfm

6.75 scfm 8.9 scfm

11 scfm

0

50

100

150

200

250

300

0 5 10 15 20

Vac

uu

m (

in H

2O

)

Distance from Test Well (feet)

Permeability Calibration for Native Soils

5 SCFM

7.5 SCFM

10 SCFM

12.5 SCFM

MeasuredVacuum

Calibrated Permeability Kr = Kz = 3.70E-08 Kc = 7.79E-08

• Leaky Confining Layer

• Low Permeable Vadose Zone

• Shallow Water Table


MDFIT


FLA – Air Sparge Modeling Results/Considerations

0.1

1

10

100

1000

10000

100000

0 5 10 15 20 25Benz

ene

Con

cent

ratio

n (u

g/L)

Air Sparging Flow Rate (SCFM)

Test Area 1 - Air Sparging Design

Lagoon FillUpper GlacialDeep Glacial

0%

20%

40%

60%

80%

100%

0 5 10 15 20 25Be

nzen

e Pe

rcen

t Red

uctio

n Air Sparging Flow Rate (SCFM)

Lagoon Fill

Upper Glacial

Deep Glacial

Test Area 1 - Design Percentage Reduction

• Mass removal rate for each COC

• Target Interval


Air Stripping Modeling

Modeling resulted in a more cost-effective

optimization strategy.

Sparging Trench Dimensions

5 to 10 ft

Where:

C L,e = COC concentration in reactor/trench effluent (ug/L), 20 ft

C L,i = COC concentration in reactor/trench influent (ug/L),

Qg = Gas or air flow rate (ft3/day),

QL = Liquid or groundwater flow rate per unit length (ft3/day),

Hc = Henry’s law constant (unitless), and Groundwater Flow

φ = Saturation parameter

Where:

K(La)COC = Mass transfer coefficient for COCs (1/day), and

V = Volume of reactor per unit length/porosity (ft3).


Remedial Strategy

EXCAVATION

• Removal and off-site disposal of approximately 2,200 tons of NAPL impacted soil - October 2012

PULSED AIR SPARGE SYSTEM

• VOCs /BTEX

• Volatilization/Stripping


• PHARMACEUTICALS (Phenol) and ALCOHOLS (Ethanol)


• METALS (Arsenic)

• Co-precipitation with dissolved minerals (i.e., iron and calcium)

• Sorption on metal/iron oxy-hydroxides SEM images of Fe-Al-Si oxy-hydroxide

precipitate formed in groundwater

(EDS analytical spectra)


FLA – Final Design • High Water Table

• Artificial Cap

• Horizontal Vapor Collection

• Leaky Confining Layer

• Impermeable Membrane

• ROI

• 10-15 feet 53 air sparge wells

• 15 feet 41 vapor collection wells

• Prevent Over Pressurization

• Pulsing Strategy

• Chimney Wells


System Design

DESIGN COMPONENTS

53 multi-level air sparge wells

41 horizontal vapor collection wells

17 vapor vent wells

11 chimney wells

2 dry wells

3-ft Clean Fill Cap

Pulsing Strategy


Engineering Design


Remedy Implementation


Strategy Benefits • System Construction Ongoing

• Startup planned for January 2015

• Anticipated Cleanup Timeframe - 3 to 5 years

• Reduced Cleanup Timeframe

• Cost Savings

• More innovative, cost effective, and sustainable in-situ remediation technology than

excavation


Questions?

Documents

CSM-2014 Air Sparge Implementation - pdf