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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, ON July 15th, 2017 by Jean Paré, P. Eng. Toronto, ON July 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, ON July 15th, 2017 by Jean Paré, P. Eng. Toronto, ON July 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 Chemco-inc.com

Chemco-inc.com

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 Oxidation

Chemical Oxidation Applicability Limitation / Disadvantage s Possible Alternative Options 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 Principles In 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
• Energetics

TNT, DNT, RDX, HMX, Perchlorate

• Metals and metalloids

As, 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

• ffers 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 tricks

Before 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

Chemco-inc.com

Tools, testing and tricks

Before you get to the field

Tools, testing and tricks

When 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 Application Troubleshooting Data Gap Analysis High Resolution Characterizatio n 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 Locations MIP 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

Reagent Per Location

9 feet = 2 feet + 7 feet @ 60 days Kinetics > 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 Reagent Per 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 Application Troubleshooting Data Gap Analysis High Resolution Characterizatio n Technology Selection 3D Graphing & Conceptual Model ROI Injection Volumes Pressure Delivery Tooling

Source – Cascade Drilling

Search and Destroy™ Methodology Targeted Distribution

Tools, testing and tricks

Tools, testing and tricks

Follow 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 Data Dry 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.com Tel: 418-953-3480 // 800-575-5422 Chemco-inc.com