1

Redox Tech, LLC Fundamentals of In-Situ Remediation

“Providing Innovative In Situ Soil and Groundwater Treatment”

2

Redox Tech, LLC

• Business founded in 1995.• Headquarters in Cary, NC. Other offices in GA,

SC, IL, MA, and CA.• New England Office opened in 2005.• In situ treatment with biological and

chemical manipulation, both reduction and oxidation – over 800 projects completed.

• In situ Soil Blending.

In Situ Remediation is a TOOL!

Site Characterization for In Situ Treatment Designs

• Horizontal and Vertical Delineation;• MNA Field Measurements (Ph, ORP, and DO);• Alkalinity, Dissolved Iron, Sulfate, etc…• Site Geology;• Total Oxidant Demand (TOD);• Utility Locations; and• Nearby Receptors.

5

In Situ Remediation – The DesignDelivery and Chemistry are Key

• Requires fundamental understanding of geochemistry and microbiology.

• Requires confidence in the consultants work.• Requires delivery that mimics the target

contaminant distribution.• Without both proper data, delivery and

formulation, remediation likely to fail. • May require Pilot Study.

6

Total Oxidant Demand (TOD)

• Water-phase contaminant is not only material that will be oxidized

• Sorbed phase contaminant• Free-phase contaminants• Naturally-occurring organic material

(NOM)• Reduced soil and water minerals• Can be estimated with site data

7

Total Oxidant Demand

Total Oxidant Demand can vary between <0.1 to 155 g/Kg

8

Treatment Classes

• Chemical Oxidation• Chemical Reduction• Aerobic Bioremediation• Anaerobic Bioremediation• Metals Stabilization• Thermal (steam)

9

Chemical Oxidants

• Permanganate – widely used for chlorinated alkenes, PCE, TCE, DCE, VC

• Peroxide (Fenton’s) – relatively inexpensive, but can be difficult to inject

• Persulfate – replacing many peroxide applications because of safety and gas generation

• Ozone – still occasionally used for gas stations

Base Activated Sodium Persulfate• Competes with permanganate, Fenton’s chemistry,

ozone and peroxide;• Oxidizes a broader range of organic contaminants

than permanganate ;• Oxidizes more compounds than Fenton’s

chemistry and does not have gas generation;• Slower reaction time than other oxidants which

can translate to less rebound; and• Much safer to handle than other oxidants.

Sodium Persulfate InjectionEnfield, CT

• Gasoline Release in the 1980s;• Remediation activities included product recovery,

SVE, pump and treat and soil excavation;• Following 20+ years of remediation, groundwater

concentration were still elevated under the roadway and nearby properties; and

• Redox Tech NE was invited to bid on a Fenton’s Reagent design and proposed activated sodium persulfate as an alternative.

Plume is approximately 17,000 Square Feet

Injection Design

• 17,000 square foot treatment area;• Average TVOC approximately 18,000 ppb;• 5 to 7 foot thickness;• 44 injection points (2 rounds); • 54,000 lbs of sodium persulfate; • 450 gallons per point;• 2 target depth intervals; and• Completed in 11 days;

Groundwater Treatment Results

• Average TVOC approximately 4,000 ppb (78%);• Elevated sulfate still present in groundwater

(>1,000 mg/L); and• 22 out of 36 target monitoring wells below

groundwater standards (GW Protection and Residential).

Groundwater Treatment Results Continued

Redox Tech’s Oxygen BioChem (OBC)

• A slow-release oxygen generating formula designed to provide short-term chemical oxidation (1-2 months) and long term anaerobic oxidation via sulfate reduction (1-2 years)

• Patented combination of sodium persulfate and food grade calcium peroxide

• Can be added to excavations or injected into groundwater

• One of the preferred products in New Hampshire • Predecessor to Klozur CR

Oxygen BioChem vs. Competitors

Oxygen BioChem (OBC) Competitors

Greater oxygen – as much as 46 wt %

Typically 10 to 20 wt %

Both chemox and biorem. Mostly bioremediation

Greater solubility –40 wt % for the persulfate portion

Typically less than 5% soluble

Better value - $3.25 per pound

Typically $4 to $10 per pound

18

Enhanced Anaerobic Bioremediation

• Aquifers are sometimes limited by carbon (or food) source for bacteria

• In some instances, the proper bacteria (e.g. dehalogenators) are not present

• Overstimulation can result in domination by methanogens

• Examples: Redox Tech’s ABC, FMC’s EHC and Regenesis’ HRC

• Data should support the use these products

19

Anaerobic BioChem (ABC)

• Sodium Lactate • Ethyl Lactate – green solvent• Fatty Acids – all dissolved• Dipotassium Phosphate for micronutrients

and pH buffering• Can bioaugment with RTB-1 (DHC)

20

ABC® Advantages

• Long lasting (2+ years) but water soluble so large volume of chase water not required

• Lower injection pressures• Does not require hydrolysis of oils to release fatty

acids• No emulsion breaking potential• No soap formation from bringing pH up to high• Demonstrated buffering

21

Anaerobic BioChem (ABC+)

• Mixture of ABC® plus zero valent iron (ZVI)

• Combination of chemical reduction (ZVI) and anaerobic bioremediation

• Less likely to form VC• Licensed with Adventus & Waterloo to add

ZVI to carbon amendment• Injected over 1,500,000 pounds ABC+

22

ZVI REACTION

• β-elimination pathway minimizes daughter products• very low concentration of chlorinated intermediates• intermediates degrade• Surface reaction at ZVI

23

Combined Bio and Chemical Reduction

Redox Potential Comparison

-800

-600

-400

-200

0

200

400

0 5 10 15 20 25 30

Treatment Time (days)

Red

ox

Po

ten

tial

(m

V)

Control ABC® ABC+®

ABC+ InjectionWrentham, MA

• 5,000 square foot area and a 15 foot thickness• Dense material with gravel, which required pre-clearing

top 5 feet with auger • 5,400 lbs of ABC+• 18 injection points with 5 depth intervals• November 2009: PCE = 1,300 ppb and TCE = 93,000 ppb• May 2010: PCE = ND < 50 ppb and TCE = ND < 50 ppb• Dissolved gases detected and cis-1,2-DCE (3,300 ppb) and

VC (910 ppb) spiked in May 2010. Cis-1,2-DEC and VC reduced in November 2010 to 670 ppb and 430 ppb.

25

Technical Advantages of Sulfate

• Exists naturally in most groundwater• High solubility in comparison to other electron

acceptors• Easily applied as an aqueous solution • Proper application of sulfate enhanced

biodegradation will result in no adverse health effects • Results are surprisingly rapid

Sulfate Reduction Case Study

Site Background Former gasoline service station with two confirmed

releases in 1992 and 2001 Historical remedial efforts with limited success

included groundwater pump and treat and monitored natural attenuation

Geology consists of fine to medium sand with groundwater present about 10 feet bgs

Pilot study was not intended to be a “full scale” site remediation

27

Jackson, Michigan October 3, 2007

0

50

100

1stQtr

3rdQtr

EastWestNorth

• Baseline Conditions Sulfate is depleted in

core Sulfate background is >

50 ppm Max. BTEX is >10,000

ppb

Sulfate

BTEX

Sulfate DepletedSulfate DepletedIn core of plumeIn core of plume

BTEX PlumeBTEX Plume

GW FlowGW Flow

28

Jackson, Michigan November 13, 2006

• 5 weeks after first application

• Sulfate is increased in core of plume – RED is >250 ppm

• Concurrently BTEX >10,000 ppb is decreasing

Sulfate

BTEX

Sulfate IncreasesSulfate Increases

Sulfate DepletedSulfate Depleted

BTEX beginning to shrinkBTEX beginning to shrink

29

Jackson, Michigan January 16, 2007

• 3 months after initial application

• Sulfate still elevated in core of plume

• BTEX >5,000 ppb is shrinking

Sulfate

BTEX

Sulfate IncreasingSulfate Increasing

BTEX ShrinkingBTEX Shrinking

30

Jackson, Michigan April 12, 2007

• 6 months after first application

• Sulfate concentrations have returned to baseline conditions

• BTEX plume is stable with reduced peak concentrations

Sulfate

BTEX

Sulfate ConsumedSulfate Consumed

BTEX ReboundingBTEX Rebounding

31

Jackson, Michigan Case Study Benefits

Accelerated cleanup Information gained significantly strengthens advocacy position

with regulatory agencies Monitoring frequency showed no lag time for acclimation of

native sulfate reducing bacteria Minimal site disruption

In-situ approach with no ongoing O&M activities Cost effective

<$2,000 worth of materials Safe

Demonstrated absence of hydrogen sulfide gas generation or any other adverse affects

Green – Natural Process

Metals Treatment

1. Lead treatment with phosphate buffer.

2. Arsenic/lead treatment with phosphate, calcium buffer and hydrogen peroxide.

3. Hexavalent chromium treatment with ferrous chloride and hydrated lime.

4. Bench Scale Study

Steam & Recovery

• Site in Lawrence, MA;• Estimated 500 gallons of No. 6 Oil;• Injected heated water into subsurface to

create steam;• Project was completed in 8 days;• Approximately 700 gallons of product was

recovered in 6 weeks; and • No measurable product;

34

Delivery Capabilities

• Proprietary injection tools that are integrated with Geoprobe.

• Permanent injection points (PVC riser and screen).• Injection of gasses, liquids and solids in largely

varying geological environments - pressures from 10 to 2000 psi (Hydraulic Fracturing).

• Excavations/Trenches.• In Situ Soil Blending for shallow soil (<25’ bgs.).

35

Why Injection Isn’t for Amateurs

36

Pump and Treat Gone Bad

37

Hydraulic Fracturing

• Injection of water, solution or slurry at pressure that exceeds the lithostatic pressure and cohesive strength of the formation.

• Results in short-term enhancement of soil permeability.

• Increases radius-of-influence and injection rate.

Hydraulic Fracturing Concept

Pressure – Time History

Fracture

Maintenance

40

ABC+ Injection Equipment

41

In Situ Soil Blending• Efficient and uniform delivery of remediation

amendments• Production rates comparable to dig, haul and backfill• No long term liability associated with disposal• Costs that can be 2 to 10 times less expensive than dig

and haul, depending upon the extent of contamination• No RCRA TSD permits are required• Can treat a wide range of compounds, such as

chlorinated solvents, pesticides, PAHs, etc

42

In Situ Soil Blending – The Beginning

43

In Situ Soil Blending - Improved

44

Improvements in Blender• Weight reduced by ~50% which reduces

transportation costs by factor of two ($5-6 per mile now)

• Horsepower approximately doubled• Independent acting dual motors in custom designed

mixing head• Torque load sensing on both sides of head so rotation

speed automatically adjusts – prevents “deadheading”• Base is common excavator so parts readily available

45

In Situ Soil BlendingCambridge, MA

Dichloroethane (DCA) Contamination

46

Post In Situ Soil Blending

47

Amendment Distribution via Electrical Conductivity Distribution

Dr. Joseph Rossabi

• Completely Integrated with Geoprobe Apply AC (current)Measure DC (voltage)Know current and voltage, calculate resistance

and convert to conductivity (inverse relation)Measurements every 0.05 ft (vertical)Lateral sensitivity < 0.5 ft

48

Background Electrical Conductivity

0

5

10

15

20

25

30

1 10 100 1000 10000

Electrical Conductivity (mS/m)

De

pth

(ft

)

EC7 = Background

100 mS/m

49

Background Electrical Conductivity and Near Injection Point

0

5

10

15

20

25

30

1 10 100 1000 10000

Electrical Conductivity (mS/m)

De

pth

(ft

)

EC1

Background

100 mS/m

50

Electrical Conductivity in the Blending Area

0

5

10

15

20

25

30

1 10 100 1000 10000

Electrical Conductivity (mS/m)

De

pth

(ft

)

EC3

EC4

EC5

Background

100 mS/m

51

USEPA Site Rhode Island

52

Treatment Area

53

Blending Activity – Day 1

• Top Photo – A view of the excavation prior to blending activity

• Bottom Photo – A view of the application of the first 1K pounds of KMnO4

54

Blending Activity – Day 1 (Continued)

• Top Photo – A view of the initial mixing with an excavator.

• Bottom Photo – A view of the soil blending thoroughly mixing the KMnO4 with the contaminated soil.

55

Day 1 – Area Completed

• 2,000 pounds of KMnO4

blended with ~ 300 cy of contaminated soil (Area shaded in purple).

• KMnO4 not observed in down gradient monitoring wells.

56

Day 5 – Area Completed

• 7,000 pounds of KMnO4

blended with ~ 1,500 cy of contaminated soil (Area shaded in purple).

• Approximately 8,500 gallons of water was used to blend the KMnO4 with the soil.

• KMnO4 observed in 3 down gradient monitoring wells ( ).

57

Day 7 – Soil Blending Completed

• 10,000 pounds of KMnO4

blended with ~ 2,100 cy of contaminated soil (Area shaded in purple).

• Approximately 10,500 gallons of water was used to blend the KMnO4 with the soil.

• KMnO4 observed in 4 down gradient monitoring wells ( ).

58

Day 12 – Post Blending Monitoring

• KMnO4 observed in 7 monitoring wells ( ).

In Situ Remediation Issues

• Underestimated contaminant mass;• Unknown underground structures;• Poorly marked utilities;• Daylighting;• Back Pressure;• Surface grade;• Aboveground obstructions; and • Poorly identified geology

60

The End

• In Situ Remediation is 1 of many tools;

• Injection is not the only application technique;

• Know your site;

• Work with your In Situ contractor;

• Understand the function of the chemical; and

• For more information: www.redox-tech.com