Transcript Redox Tech, LLC Fundamentals of In-Situ Remediation “Providing Innovative In Situ Soil and Groundwater Treatment” Redox Tech, LLC • Business founded in 1995. • Headquarters in.

Redox Tech, LLC
Fundamentals of In-Situ Remediation
“Providing Innovative In Situ Soil and
Groundwater Treatment”
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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.
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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.
In Situ Remediation – The Design
Delivery and Chemistry are Key
• Requires fundamental understanding of
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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.
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Total Oxidant Demand (TOD)
• Water-phase contaminant is not only
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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
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Total Oxidant Demand
Total Oxidant Demand can vary between <0.1 to 155 g/Kg
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Treatment Classes
• Chemical Oxidation
• Chemical Reduction
• Aerobic Bioremediation
• Anaerobic Bioremediation
• Metals Stabilization
• Thermal (steam)
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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
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Base Activated Sodium Persulfate
• Competes with permanganate, Fenton’s chemistry,
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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 Injection
Enfield, 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
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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
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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
Enhanced
Anaerobic Bioremediation
• Aquifers are sometimes limited by carbon (or
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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
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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)
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ABC® Advantages
• Long lasting (2+ years) but water soluble so large
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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
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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+
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ZVI REACTION
• β-elimination pathway minimizes daughter products
• very low concentration of chlorinated intermediates
• intermediates degrade
• Surface reaction at ZVI
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Combined Bio and Chemical Reduction
Redox Potential (mV)
Redox Potential Comparison
400
200
0
-200 0
-400
-600
-800
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Treatm ent Tim e (days)
Control
ABC®
ABC+®
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ABC+ Injection
Wrentham, MA
• 5,000 square foot area and a 15 foot thickness
• Dense material with gravel, which required pre-clearing
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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.
Technical Advantages of Sulfate
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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
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Sulfate Reduction Case Study
Site Background
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Former gasoline service station with two confirmed
releases in 1992 and 2001
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Historical remedial efforts with limited success
included groundwater pump and treat and
monitored natural attenuation
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Geology consists of fine to medium sand with
groundwater present about 10 feet bgs
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Pilot study was not intended to be a “full scale” site
remediation
Jackson, Michigan October 3, 2007
Sulfate Depleted
In core of plume
Sulfate
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GW Flow
1st
Qtr
3rd
Qtr
East
West
North
BTEX
Plume
BTEX
• Baseline Conditions
 Sulfate is depleted in
core
 Sulfate background is >
50 ppm
 Max. BTEX is >10,000
ppb
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Jackson, Michigan November 13, 2006
Sulfate
Sulfate Increases
• 5 weeks after first
Sulfate Depleted
BTEX
BTEX beginning to shrink
application
• Sulfate is increased in
core of plume – RED is
>250 ppm
• Concurrently BTEX
>10,000 ppb is decreasing
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Jackson, Michigan January 16, 2007
Sulfate
Sulfate Increasing
• 3 months after initial
BTEX
BTEX Shrinking
application
• Sulfate still elevated in
core of plume
• BTEX >5,000 ppb is
shrinking
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Jackson, Michigan April 12, 2007
Sulfate
Sulfate Consumed
BTEX
BTEX Rebounding
• 6 months after first
application
• Sulfate concentrations
have returned to
baseline conditions
• BTEX plume is stable
with reduced peak
concentrations
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Jackson, Michigan Case Study
 Benefits
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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
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Metals Treatment
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Lead treatment with phosphate buffer.
Arsenic/lead treatment with phosphate, calcium
buffer and hydrogen peroxide.
Hexavalent chromium treatment with ferrous
chloride and hydrated lime.
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;
Delivery Capabilities
• Proprietary injection tools that are integrated with
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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.).
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Why Injection Isn’t for Amateurs
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Pump and Treat Gone Bad
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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.
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Hydraulic Fracturing Concept
GROUT HEAD - ATTACHES
TO GEOPROBE RODS
" NYLOBRADE FLEXIBLE PVC HOSE
PUMP
GEOPROBE RIG
GEOPROBE RODS
GROUND SURFACE
UNFRACTURED SOIL
SEAL AROUND GEOPROBE RODS
WITH BENTONITE AS RODS
ARE PUSHED.
SEE DETAIL "A"
FRACTURED
ZONES
AFTER FRACTURE
(Connection & Diffusion Controlled)
BEFORE FRACTURE
(Diffusion Controlled)
DETAIL "A"
VAPOR MOVEMENT IN SOIL MICROSTRUCTURE
Pressure – Time History
Fracture
Maintenance
ABC+ Injection Equipment
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In Situ Soil Blending
• Efficient and uniform delivery of remediation
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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
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In Situ Soil Blending – The Beginning
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In Situ Soil Blending - Improved
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Improvements in Blender
• Weight reduced by ~50% which reduces
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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
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In Situ Soil Blending
Cambridge, MA
Dichloroethane (DCA) Contamination
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Post In Situ Soil Blending
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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
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Background Electrical Conductivity
Electrical Conductivity (mS/m)
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1000
10000
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Depth (ft)
10
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EC7 = Background
100 mS/m
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Background Electrical Conductivity and Near Injection Point
Electrical Conductivity (mS/m)
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100
1000
10000
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Depth (ft)
10
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EC1
Background
100 mS/m
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Electrical Conductivity in the Blending Area
Electrical Conductivity (mS/m)
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100
1000
10000
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Depth (ft)
10
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EC3
EC4
EC5
Background
100 mS/m
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USEPA Site
Rhode Island
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Treatment Area
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Blending Activity – Day 1
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Top Photo – A view of the
excavation prior to blending
activity
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Bottom Photo – A view of the
application of the first 1K
pounds of KMnO4
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Blending Activity – Day 1 (Continued)
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Top Photo – A view of the
initial mixing with an
excavator.
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Bottom Photo – A view of the
soil blending thoroughly mixing
the KMnO4 with the
contaminated soil.
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Day 1 – Area Completed
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2,000 pounds of KMnO4
blended with ~ 300 cy of
contaminated soil (Area shaded
in purple).
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KMnO4 not observed in down
gradient monitoring wells.
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Day 5 – Area Completed
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7,000 pounds of KMnO4
blended with ~ 1,500 cy of
contaminated soil (Area shaded
in purple).
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Approximately 8,500 gallons of
water was used to blend the
KMnO4 with the soil.
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KMnO4 observed in 3 down
gradient monitoring wells ( ).
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Day 7 – Soil Blending Completed
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10,000 pounds of KMnO4
blended with ~ 2,100 cy of
contaminated soil (Area shaded
in purple).
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Approximately 10,500 gallons
of water was used to blend the
KMnO4 with the soil.
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KMnO4 observed in 4 down
gradient monitoring wells ( ).
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Day 12 – Post Blending Monitoring
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KMnO4 observed in 7 monitoring
wells ( ).
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In Situ Remediation Issues
• Underestimated contaminant mass;
• Unknown underground structures;
• Poorly marked utilities;
• Daylighting;
• Back Pressure;
• Surface grade;
• Aboveground obstructions; and
• Poorly identified geology
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
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