Tools and Methods to Reduce Uncertainties Associated with the Use of In Situ Remediation

Techniques for Organic Contaminants in Soil and Groundwater

Tools and Methods to Reduce Uncertainties Associated with the Use of In Situ Remediation

Techniques for Organic Contaminants in Soil and Groundwater

by Jean Paré, P. Eng.

Toronto, ONJuly 15th, 2017

by Jean Paré, P. Eng.

Toronto, ONJuly 15th, 2017

The Chemistry works but the geology screws it up …The Chemistry works but the geology screws it up …

by Jean Paré, P. Eng.

Toronto, ONJuly 15th, 2017

by Jean Paré, P. Eng.

Toronto, ONJuly 15th, 2017

Presentation Agenda� In Situ Technology Review and Limitations� Field application challenges and contact issue� Tools, testing and tricks

• Before you get to the field• When you’re in the field• Follow up After injection events

� Case Study Presentation

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In Situ Technology – Key Drivers� Time versus Money� Contaminant Accessibility (infrastructures, utilities)� Sustainability Contribution (remote disposal site, landfilling without treatment, Energy Output)� Polishing steps to achieve Risk Based Criteria� Improvement of contaminant removal rate versus natural attenuation

Chemical Oxidation – Technology Review � Oxidants are introduced or mixed into the soil and groundwater to attack the organic contaminants� Chemical oxidation treatments are commonly used in potable and wastewater applications� Oxidants are non-specific and will react with the targeted contaminants AND with the soil organic content a value called Soil Oxidant Demand - SOD.� Chemical oxidation reactions involve the transfer of electrons and the breaking of chemical bonds� Water is the carrier for the oxidants used in chemical oxidation (except for ozone)� If you have enough oxidant present and sufficient time you will push reaction to FULL mineralization (CO2, H2O, Cl-) of the contaminant of concern � Chemical oxidation can slow down the biological activity but will NOT sterilize the soil completely (potential benefit because of

lower toxicity after the Chemical Oxidation is completed)

Chemical Oxidation – Technology Review Common Chemical Oxidants � Potassium or sodium permanganate� Hydrogen Peroxide alone� Catalyzed Hydrogen Peroxide

• Hydrogen Peroxide with iron (regular Fenton reagent reaction)• Need to establish acidic conditions (ideal pH between 4 and 6)• Modified Fenton Reagent with chelated metals (neutral pH)

� Ozone• Ozone is a gas and must be produced on site • The gas must be injected into the soil

� Persulfate• Requires activation to generate free sulphate radicals. • Heat, chelated metal, high pH, surface, organic or hydrogen peroxide can be used to activate the persulphate. Activation method can be adapted to site conditions.

� Percarbonate• Requires activation to generate free radicals

SAFETY NOTE:ALL THESE PRODUCTS REQUIRE ADEQUATE HANDLING PRATICES AND SAFETY EQUIPMENT.

Chemical Oxidation – Limitations (1) � All chemical oxidation reactions occur in the WATER or moisture phase (except for ozone)� Kinetics of the chemical oxidation reaction is thus influence by the contaminant of concern solubility and availability in the groundwater or moisture phase � Sorbed phase contamination might be challenging to remediate (less available)� In NAPL containing sites, contamination can persist because of the highly hydrophobic properties of the chemicals that make up the NAPLs� Injection technique must induce proper contact between the contaminant and the oxidant for a proper duration for the required reaction to occurs (kinetics)

Chemical Oxidation – Limitations (2)� All oxidants can change the oxidation state of metals and thus

increase their solubility and mobility� Metals of particular concern are: chrome, lead, uranium,

selenium, vanadium� In most of these cases, the metals will come back in their

reduced state once all of the oxidant has been consumed by the environment

� Impurities contained in the oxidant must be evaluated� In the case of arsenic, oxidation will help immobilizing the metal

by reducing its solubility

Conditions for Selecting Chemical OxidationChemical Oxidation Applicability

Limitation / Disadvantages

Possible AlternativeOptions

Mobile NAPL Probably not the best choice

High oxidant requirement ($)

Liquid Extraction Thermal degradation

Residual NAPL (10,000’s mg/kg)

Yes, but difficult

High oxidant requirement ($)

Extraction with air/steam injection Thermal degradation

High conc. in soil/groundwater (10’s – 10000’s mg/kg)

Yes, good conditions

Normal considerations

Extraction with air/steam injection Bioremediation

Dissolved plume (< 1 mg/kg)

Yes, but could be costly

Higher cost due to SOD

Bioremediation, Reactive barriers

Source : ITRC 2004 NAPL: Non-Aqueous Phase Liquid

Compatibility oxidant/contaminant

L=Low G=Good E=Excellent 1=Perozone

Contaminant/Oxydant MnO4 S2O8 SO4* Fenton’s Ozone Petroleum Hydrocarbon L G/E E E E BTEX L G G/E E E Phenols G L/G G/E E E1 Polycyclic Aromatic Hydrocarbon (PAH)

L G E E E

MTBE L L/G E G G Chlorinated Ethenes (PCE, TCE, DCE, VC)

E G E E E

Carbon Tetrachloride L G L/G L/G L/G Chlorinated Ethanes (TCA, DCA)

L G G/E G/E G

Polychlorinated Biphenyls (PCB)

L L L G/E G1

Energetics (RDX, HMX) E G E E E Source: Carus Chemical Company

Enhanced Bioremediation Advantages� Enhances natural in-situ processes already at play (typically

uses natural groundwater gradient, naturally occurring biodegradation.

� Low energy and cost effective

� Relatively easy to manage and handle.

� Can be used in tandem with other remedial technologies that address small amounts of residual soil and groundwater contamination

Parameters to consider for a successful enhanced bioremediation� Temperature, pH

� Nutrients Balance (C:N:P ratio)

� Site geology and hydrogeology consideration

� Proper micro-organisms presence

� Aerobic or anaerobic conditions to support bioremediation in soil and groundwater.

Chemical Reduction PrinciplesIn situ // Ex situ• In Situ Chemical Reduction (ISCR) is defined as “a

process that combines biotic and abiotic reactions to treat contaminants by creating reducing conditions”

• ISCR can be enhanced by anaerobic bioremediation

• ISCR also provides abiotic/chemical degradation component if a metal (zero valent iron or other) is present

Chemical Reduction Compatibility reductant/contaminant� Chlorinated Compounds

• PCE, TCE, cDCE, 11DCE, VC• 1122TeCA, 111TCA, 12DCA• CT, CF, DCM, CM

� Herbicides, Pesticides•Toxaphene, Chlordane, Dieldrin, Pentachlorophenol

� EnergeticsTNT, DNT, RDX, HMX, Perchlorate

� Metals and metalloidsAs, Cr, Pb, Zn, Cd, Hg, Cu, Cr, Ni, Sb, Co� Under aerobic conditions you can target

HAP, phtalates, perchlorate, petroleum hydrocarbon

In Red: need to have an organic substrate and/or a ZVI/carbon combination

Common Chemical Reducing Agents• Sugars

• Molasses• high fructose corn syrup• whey

• Fatty acids • Lactate• Butyrate• propionate

• Emulsified Vegetable Oils• Soybean Oil

• Complex Fermentable Carbon complex• lecithine• polylactate

• Zero Valent Iron (ZVI)• Soluble Iron Compounds

Selection Factors –Chemical Reductant

• ORP of the aquifer• Hydrogen vs. Acidity produced• Biodegradation rate / longevity• Ease of injection and distribution

Soil Washing – Technology Review� Organic Contaminants (Petroleum hydrocarbon,

PCB, Dioxin, Furans, etc.) are entrapped as pure product (free phase) or at high concentration in various soil matrix. � Highly contaminated soils are bringing challenges for

an effective low cost remediation. � Soil Washing using co-solvent and/or surfactant

offers the benefit to treat effectively and economically these high contaminant concentration that allow for soil to be re-used or dispose at a lower cost.

Activated Carbon – Technology Review� Contaminants sorb to activated carbon � Decreases groundwater mass immediately � Disrupts groundwater/soil mass equilibrium to help drive

desorption � Concentrated mass accelerates degradation rates � Various degradation mechanisms are used to treat•

Bioremediation (aerobic/anaerobic) � Chemical reduction/oxidation

Source: AST

Field application challenges and contact issue

� Good treatment require good contact� Application challenges� Geology (Silts and Clays, Sands, gravel and other)� Heterogeneity� Low GW Velocity� < Fracture Pressures� High Volumes to inject� Reagent Kinetics� Depth

- Shallow environment- Deep environment

Tools, testing and tricksBefore you get to the field� Validating the qualification and quantification of the selected amendment with bench scale lab study

Soil and Groundwater amendment validation and treatability study are ALWAYS recommended(If it doesn't work in the lab in ideal contact conditions it WON’T work in the field)

� Make sure you have all the necessary data and your injection plan is set properly

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Tools, testing and tricks

Before you get to the field

Tools, testing and tricksWhen you’re in the field

� Making sure you are injecting in the adequate zone SITE CHARACTERIZATION IS KEY� Validating the distribution and dilution of the amendment in the subsurface aquifer through the use of an INERT tracer PRIOR to moving in with your expensive oxidant or amendment. � Evaluate the pro and cons of the various equipment and techniques to induce proper contact � Confirm Injection Pressure and Flow Assumptions� Confirm Formation Acceptance of Design Volume � Confirm Vertical and Horizontal Distribution of Reagents Over

Time

Search and Destroy™ Methodology Targeted Distribution

Source – Cascade Drilling 23

High Resolution

Remediation Design

Distribution Testing

Optimized Full Scale

ApplicationTroubleshooting

Data Gap Analysis

High Resolution

Characterization

Technology Selection

3D Graphing & Conceptual

Model

Tools, testing and tricks

Search - Why MIP/HPT or LIF before injecting ?

� Locate contaminant mass through high vertical resolution � Define injection flows and

pressures� Don’t get fooled by tight

sands or clays with low conductivity

MIP 3D Imaging –Injection LocationsMIP 3D Imaging –Injection Locations

Radius of Influence (ROI)

Advection / Dispersion ROI

Additional ROI from Advection

/ Dispersion (Feet)

Time Frame To Achieve

Advection / Dispersion ROI

(Days)

7 feet 60 Days

ROI

60 days

9 feet

ROI = PROI + A/DROI

ROI = pore volume ROI (ft) + advection/dispersion ROI (ft)

Pore Volume ROI

100%

Injection Volume as a

% of Effective

Pore Volume

2 feet

Pore Volume ROI

500 gals

ReagentPer

Location

9 feet = 2 feet + 7 feet @ 60 daysKinetics > ROIT

+ =

4’

10’

ROI Realities

Advection / Dispersion ROI

Additional ROI from

Advection / Dispersion

(Feet)

Time Frame To Achieve Advection / Dispersion ROI (Days)

7 feet 60 Days

ROI

60 days

9 feet

Pore Volume ROI

50%

Injection Volume as

a % of Effective

Pore Volume

2 feet

Pore Volume ROI

500 gals

ReagentPer

Location

Tight Soils

• Low Injection Pore Volumes

• Tighter Spacing

• Higher Reagent Concentrations

• Reagent Persistence

• Exceed Fracture Pressure

Permeable Soils / Flat Gradient

• Requires High Injection Pore Volume

• Stay Below Fracture Pressure

Permeable Soils / Steep Gradient

• Lower Residence Time

High Resolution

Remediation Design

Distribution Testing

Optimized Full Scale

ApplicationTroubleshooting

Data Gap Analysis

High Resolution

Characterization

Technology Selection

3D Graphing & Conceptual

Model

ROIInjection Volumes

PressureDelivery Tooling Source – Cascade Drilling

Search and Destroy™ Methodology Targeted Distribution

Tools, testing and tricks

Tools, testing and tricksFollow up After injection events� Validate oxidant/amendment distribution (may integrate inert tracer to evaluate dilution factor) with :

• Core samples • Hydro punch sampling• Electrical Conductivity• Groundwater sampling through monitoring

wells

Injection

Strategic Injection Strategy

Case Study 1 - Outputs Visual DataDry Cleaner Case Study

Source: Cascade Drilling

Injection

Strategic Injection Strategy

Post-Injection MIP

Pre-Injection MIP

Source: Cascade Drilling

Case Study 1 - Outputs Visual Data MIP Post Injection

About our Expertise, Products and Services � Training and Education: technical transfer session, health

and safety training;� Technology Site Assessment: technology support and

selection (chemical oxidation, co solvent-surfactant soil washing and enhanced bioremediation);� Products supply, logistic and storage: nutrients, bacterial

preparations strains, oxidants, catalysts, oxygen and hydrogen release compounds, co solvent-surfactant blends� Laboratory Services and Analysis: Groundwater

Parameter Analysis, Tracer Study, Soil and Groundwater Oxidant Demand Evaluation (SOD), Bench Scale Treatability testing.

Acknowledgements� Carus Chemical � AST� EOS� Peroxychem� Progressive Engineering & Construction� Vertex Environmental Inc.� Cascade Drilling

Thank you for your attention !Have a good day !!!

E-mail: jean.pare@chemco-inc.comTel: 418-953-3480 // 800-575-5422

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