Successful Remediation of Residual DNAPL in Tight Materials S. - - PowerPoint PPT Presentation

Successful Remediation of Residual DNAPL in Tight Materials

• S. Markesic, J.Rossabi, J.S. Haselow (Redox Tech, LLC)

REDOX TECH, LLC

REDOX TECH, LLC

Overview

 Residual DNAPL and difficulties with

remediation

 Summary of Remediation Techniques Available  Case Studies

Residual DNAPL

Referring to concentrations where there is no accumulation of free product, but when DNAPL

• ccurs as disconnected singlet and multi-pore globules

within the pore spaces.

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UNSATURATED ZONE (NAPL as the intermediate wetting fluid) SATURATED ZONE (NAPL as the non-wetting fluid) NAPL Air Soil Particles

Problems With Treating residual DNAPL in Low Permeable Soils

 Often not well delineated  Concentrations can vary considerably in short distances  Distribution/Extraction  Contact  Chemistry (Clays typically have higher Oxidant

Demands)

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Yes but…..



How long do you have?



What are the cleanup objectives?



What access do I have?

Can we Remediate Residual DNAPL in Clay Soils?

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Remediation Approaches

Three Types of approaches:

 1) Removal  2) Immobilization  3) Destruction

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Removal Approach

 Includes:

 Dissolution (increase solubility of

product)

 Surfactants, cosolvents, increase

temperature

 Displacement (reduce capillary forces)

 Surfactants, cosolvents, increase

temperature

 Volatilization (transfer contaminant to

vapor phase) Excavation (physically remove)

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Requires an extraction process (e.g. dual phase and some way to enhance permeability (e.g. fracturing)

Immobilization Approach

 Isolate Source from Surroundings

 Barrier Walls  In place encapsulation (cement, bentonite)  Pump and Treat (prevent movement)  Vitrification (solidify)

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Destruction Approach



Chemically Reduce the contaminant



Chemical Oxidation (potassium permanganate, sodium persulfate, hydrogen peroxide, etc.)



Chemical Reduction (e.g. ZVI)



Biodegradation



Electron Donor/Acceptor and/or bacteria culture

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Or a combination

Problems in Tight Soils

“The problem with a destruction approach is that it involves delivering an amendment into a matrix that does not readily allow for dispersion, advection, and diffusion in an acceptable time period”

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UNFRACTURED SOIL FRACTURED TO GEOPROBE RODS ZONES

BEFORE FRACTURE (Diffusion Controlled) AFTER FRACTURE (Connection & Diffusion Controlled) DETAIL "A"

VAPOR MOVEMENT IN SOIL MICROSTRUCTURE SEE DETAIL "A" GROUT HEAD - ATTACHES GEOPROBE RODS SEAL AROUND GEOPROBE RODS WITH BENTONITE AS RODS GEOPROBE RIG ARE PUSHED. GROUND SURFACE PUMP " NYLOBRADE FLEXIBLE PVC HOSE

Pneumatic or Hydraulic Fracturing

Techniques for Solving Distribution Issues

1) Fracturing

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2) Tweak Design

 Decrease injection spacing (i.e. increase number

• f points)

 Inject at discrete vertical increments to

maximize vertical distribution

Techniques for Solving Distribution Issues

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Techniques for Solving Distribution Issues

3) Soil Mixing

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Techniques for Solving Distribution Issues

• Electokinetic Migration of Permanganate, Lactates, or

hydrogen generation via electrolysis

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4) Electrokinetics (maybe….)

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Case Study #1

 Industrial Site in Ohio  Site soil consisted of silt and clay  TCE in Soil as high as 63,000 ppm  Years of active SVE was ineffective  ISCO with In Situ Soil Blending selected as best

approach

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Case Study #1

 3,450 cubic yards from ground

surface to 20 ft bgs over 10 day period

 78,662 lbs of potassium

permanganate (based on stoichiometric demand and background soil oxidant demand)

 During soil blending the SVE

system was removed

 Project completed for $286,700

(~$91 per cubic yard)

 41 post blending soil samples were collected

Case Study #1

Pre Treatment (mg/kg) Post Treatment (mg/kg) Remedial Goal (mg/kg) Maximum Average Maximum Average Area A 4,200 226 390 265 1,948 Area B 583 155 380 121 Area C 63,000 902 1,300 302

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Case Study #2

 Industrial Site in Illinois  Vadose Zone application in clays and silts from

4 to 8 feet bgs (500 square ft).

 TCE in Soil as high as 10,000 ppm  Prior mixing using a conventional backhoe with

a peroxygen ineffective at achieving remedial target (1,300 mg/kg = soil saturation limit).

 Soil concentrations remained at 7,000 ppm

Case Study #2

 In Situ Soil Blending with Potassium Permanganate

selected

 Applied 2,670 lbs of Potassium Permanganate  Work completed in one day for $17,500 (~$233 cubic

yard)

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Trichloroethene (TCE) Oxidation Results

2000 4000 6000 8000 10000 12000 9/9/2008 10/29/2008 12/18/2008 2/6/2009 3/28/2009 5/17/2009 7/6/2009 Sample Date Concentration (mg/kg)

CS-6 (6 to 7 ft bgs) CS-7 (6 to 7 ft bgs) GP-2-CS (4 o 8 ft bgs)

In Situ Soil Blending

Case Study #2

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Case Study #3

 Active Drycleaner in Illinois  Very tight clays at depths from

4 to 20 ft bgs

 PCE concentrations in soil as

high as 7,000ppm

 Majority of impact under the building  Due to existing reducing conditions,

active facility, and depth, flexible timetable, selected ERD via injection approach

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Case Study #3

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Repeat Application In 2012 Limited scale pilot test conducted in 2009 Full scale conducted in 2010. Injected 2,900lbs of ABC+. 1,860 gallons injecting at 1 ft intervals from 4 to 20 feet bgs. (2 gallons per interval). In 2012 conducted follow up Injections within the source area and back alleyway with 700 lbs of ABC+ All 3 events conducted for ~$41k. Source Area

Case Study #3

Soil PCE Concentrations from areas of Highest Impact (mg/Kg)

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• Achieved up to 99 percent

reduction in multiple areas

• Cleanup Objectives were based
• n Tier 2 modeling showing no

migration off site

• Site closed in conjunction with

a groundwater use restriction

PCE (mg/kg) Location Depth PRE POST-4 Months POST – 8 Months POST – 15 Months Reduction 1 4 7 6987.2 5649.5 175 63.1 0.687 1.48 NA NA 99.99 99.97 2 4 7 3219.9 4209.2 NA NA NA NA 0.87 6.8 99.97 99.84 3 4 150 <0.128 42.5 NA 71.67

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Case Study #3 Groundwater Concentrations (mg/L)

0.202 105 9.33 5.7 Post (4-months) 0.01 0.799 0.261 41.6 Pre VC Cis- DCE TCE PCE MW-13 0.202 105 9.33 5.7 Post (4-months) 0.01 0.799 0.261 41.6 Pre VC Cis- DCE TCE PCE MW-13 <0.05 4.48 0.298 1.6 Post (4-months) 0.014 3.659 0.437 31.74 Pre VC Cis- DCE TCE PCE MW-11 <0.05 4.48 0.298 1.6 Post (4-months) 0.014 3.659 0.437 31.74 Pre VC Cis- DCE TCE PCE MW-11 MW-12 PCE TCE Cis- DCE VC Pre 24.5 0.261 0.799 <0.002 Post (4-months) <0.01 <0.01 0.472 1.21

Summary

Remediation of residual DNAPL in low permeable sediments is possible, however the cleanup objectives, time to complete, and accessibility will ultimately define success MCLs difficult if unlikely, but reduction of mass to levels where Tier 2 criteria can be applied is manageable Single application success is rare. Multiple applications should be expected.

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Thank You Questions?

Steve Markesic (630) 705-0390 markesic@redox-tech.com