1,4-DIOXANE REMEDIATION IN GROUNDWATER -

TECHNOLOGY SURVEY AT WORLDWIDE SITES

Clean Up Conference 2019

Emerging Contaminant Session 9 September 2019

W Gary Smith, PE AECOM USA & Australia

INTRODUCTION – EMERGING CONTAMINANT CONCERNS • Focus of Clean Up 2019 is Emerging

Contaminants including 1,4-Dioxane and PFAS in Groundwater

• 1,4-Dioxane (DXA) - a likely human carcinogen – found in groundwater (GW) throughout the United States (US) and worldwide

• Physical & chemical properties & behaviour of DXA create challenges for characterization and treatment in the environment Highly mobile & completely miscible in GW Does not readily biodegrade in soil/GW

environment Unstable in vapour form at elevated

temperatures and pressures - may form explosive mixtures in air

INTRODUCTION – EMERGING CONTAMINANT CONCERNS – DXA PHYSICAL/CHEMICAL TRAITS • 1,4-dioxane (DXA) produced by acid-catalysed dehydration

of diethylene glycol, which in turn is obtained from the hydrolysis of ethylene oxide

• Heterocyclic organic compound, classified as an ether • Colorless liquid with a faint sweet ether-like odour • 1,4-DXA is often called simply “dioxane” because other

isomers (1,2- and 1,3-) are rarely encountered • In 1985, global production capacity of dioxane was between

11,000 and 14,000 tons • In 1990, US production of dioxane was between 5,250 and

9,150 tons (1)

(1) Source: Wikipedia 2019

INTRODUCTION – EMERGING CONTAMINANT CONCERNS – DXA PHYSICAL/CHEMICAL TRAITS • 1,4-dioxane (DXA) is an aprotic (incapable of

acting as a proton donor) ether • Relatively inert under various conditions with

outstanding stability at high pH • Moderate boiling point allows for easy

separation and recovery from reaction mixtures during synthesis

• Modern industry produces high purity (99.95%), low moisture (<100 ppm) DXA product

• Important physical and chemical properties of DXA are summarized in Table 1 (2)

(2) US Environmental Protection Agency (USEPA), Land & Emergency Mgmt (2017) ,Technical Fact Sheet - 1,4-Dioxane, EPA 505-F-17- 011, 8 p

INTRODUCTION – EMERGING CONTAMINANT CONCERNS – DXA PHYSICAL/CHEMICAL TRAITS

Table 1 Physical and Chemical Properties of 1,4-Dioxane (DXA) (2)

Chemical Abstracts Service (CAS) ID 123-91-1

Physical description (at room temperature) Clear, flammable liquid with a faint, pleasant odor

Molecular weight (g/mol) 88.11

Water solubility Miscible @ 100%

Melting point (degC) 11.8

Boiling point (degC) at 760 mm Hg 101.1

Flash Point degC 11

Viscosity [mPa∙s] (25 degC) 1.19

Vapor pressure at 25 degC (mm Hg) 38.1

Specific gravity 1.033

Octanol-water partition coefficient (log Kow) -0.27

Henry’s law constant at 25 degC (atm-m3/mol) 4.80 X 10-6

INTRODUCTION – EMERGING CONTAMINANT CONCERNS – DXA SOURCES & WHEREABOUTS • DXA likely present at numerous US and worldwide DXA manufacturing

sites due to spills & leaks, process area maintenance, operational issues

• DXA is a likely contaminant at many sites contaminated with chlorinated solvents (CHC), including military sites worldwide (2)

Widespread use historically as stabilizer for CHC’s in aluminum containers - particularly 1,1,1-trichloroethane [TCA]

• Byproduct present in many goods (eg, paint strippers, dyes, greases, antifreeze and aircraft deicing fluids, deodorants, shampoos, cosmetics, purifying agent for pharmaceuticals

• Byproduct in the manufacture of polyethylene terephthalate (PET) plastic

• Traces found in food supplements, food residues, DXA-containing pesticides applied to food crops

(2) US Environmental Protection Agency (USEPA), Land & Emergency Mgmt (Nov 2017) Technical Fact Sheet – 1,4-Dioxane, EPA 505-F-17- 011, 8 p.

• DXA is considered an emerging organic contaminant in the environment due to 1) detection in potable water supplies, 2) difficulty of detection at low ppb concentrations in GW, 2) high solubility in GW, 3) high migration potential re: other GW contaminants (eg, CHCs), and 4) late-developing GW remedial technologies providing very low DXA detection

• Typically found as a residual at low ppm or ppb concentrations in groundwater, but may be found at high ppm/ppt concentrations at DXA chemical manufacturing sites

• One of the last US manufacturers of DXA is shutting down in 2019 due to increasing regulatory scrutiny and perceived environmental risk.(3)

• As of 2016, DXA had been identified at more than 34 USEPA National Priorities List (NPL) sites; it is likely present at many other USA governmental/military and industrial sites (2)

INTRODUCTION – EMERGING CONTAMINANT CONCERNS – DXA SOURCES & WHEREABOUTS

(3) Editorial Staff, WAFB Television Baton Rouge Louisiana Video News (15 January 2019) Chemical Plant in Zachary, LA to Shut Down in April 2019, TV Video..

CURRENT STATUS OF DXA REMEDIAL TECHNOLOGIES Sources of DXA GW Contamination – Military Sites Worldwide

(4) Air Force Toxic Release Inventory, 11th Annual International Workshop on Solvent Substitution and Elimination, Col R. Miller, Dec 2000.

Table 2 Examples of Military Processes That Are Potential Sources of 1,4-Dioxane Releases (4)

Vapor degreasing, solvent distillation, or solvent recovery processes

Industrial/municipal waste disposal sites (landfills, waste pits, evap ponds, etc)

Manufacture, assembly, maintenance activities on launch / solid rocket motors

Manufacture, maintenance and cleaning of systems tubing for air, fuel, etc

Surface coating/stripping activities Electronic component cleaning

Electromechanical device cleaning De-icing / cooling fluids, oil/water separator waste disposal

Maintenance of aircraft, motor vehicle, aviation ground support equipment

General purpose small arms, ordnance, fuse maintenance and production

Weapons/weapon system maintenance and cleaning

O&M of installation printing plants

Fire training activities Cleaning agent in non-destructive testing

INTRODUCTION – EMERGING CONTAMINANT CONCERNS – DXA CHARACTERISTICS IN GW • Remediation focus on DXA typically on GW that may be used as a potable

source • Ongoing risk assessments by federal and state agencies have increasingly

lowered the acceptable risk level to low ppb concentrations (typically <5 ug/L) (5)

• Low risk and detection levels present an issue for both remediation technology efficiency, and ability to detect DXA at allowable groundwater concentrations in GW

• DXA does not bind to soils and migrates preferably to groundwater pore spaces where it may migrate much more rapidly than co-contaminants such as chlorinated solvents

• Thus DXA often found at leading edge of groundwater plumes that exhibit multiple co-contaminants (6)

(5) Agency for Toxic Substances and Disease Registry (ATSDR) (2012). “Toxicological Profile for 1,4- Dioxane,” web address: www.atsdr.cdc.gov/toxprofiles (6) USEPA (2006) Treatment Technologies for 1,4-Dioxane: Fundamentals and Field Applications, EPA 542-R-06-009, web address: clu-in.org/download/542r06009/pdf

Typical DXA Migration in CHC-Contaminated GW

INTRODUCTION – EMERGING CONTAMINANT CONCERNS – DXA CHARACTERISTICS IN GW

Land Surface

CHC Plume

DXA Plume

Horizontal Plume Migration

Vertical Plume M

igration

Well detects CHC

Well detects DXA

CURRENT STATUS OF DXA TOXICITY ASSESSMENTS US FEDERAL AND STATE RISK VALUES FOR DXA IN GW (5)

Table 2 State Guidelines for DXA Environmental Limit

State Guideline (μg/L) Source Alaska 77 AL DEC 2016 California 1.0 Cal/EPA 2011 Colorado 0.35 CDPHE 2017 Connecticut 3.0 CTDPH 2013 Delaware 6.0 DE DNR 1999 Florida 3.2 FDEP 2005 Indiana 7.8 IDEM 2015 Maine 4.0 MEDEP 2016 Massachusetts 0.3 MADEP 2004 Mississippi 6.09 MS DEQ 2002 New Hampshire 0.25 NH DES 2011 New Jersey 0.4 NJDEP 2015 North Carolina 3.0 NCDENR 2015 Pennsylvania 6.4 PADEP 2011 Texas 9.1 TCEQ 2016 Vermont 3.0 VTDEP 2016 Washington 0.438 WA ECY 2015 West Virginia 6.1 WV DEP 2009

(5) Agency for Toxic Substances and Disease Registry (ATSDR) (2012. “Toxicological Profile for 1,4-Dioxane,” www.atsdr.cdc.gov/toxprofiles

CURRENT STATUS OF DXA TOXICITY ASSESSMENTS US FEDERAL RISK AND WORKER SAFETY VALUES FOR DXA (2,5)

Table 3 Federal Guidelines for DXA Environmental Limit

Type Guideline (μg/L) Source IRIS Chronic Reference Dose (RfD) 0.03 mg/kg/day Liver and kidney toxicity in animal studies IRIS Chronic Inhalation Reference Conc (RfC) 0.03 mg/m3 Atrophy/respiratory metaplasia inside nasal cavity of animals IRIS Cancer Risk Oral Slope Factor 0.1 mg/kg/day Drinking water risk studies and risk calculations IRIS Drinking Water Unit Cancer Risk 2.9x10E-6 ug/L Drinking water risk studies and risk calculations IRIS Drinking Water 1x10E-6 Risk Level 0.35 μg/L Drinking water risk studies and risk calculations USEPA Drinking Water Equivalent Level 1 mg/L Drinking water risk studies and risk calculations USEPA Tap Water Screening Level 0.46 μg/L Drinking water risk studies and risk calculations based on

1x10E-6 lifetime cancer risk USEPA Drinking Water 1-Day and 10-Day Health Advisory; Lifetime Health Advisory

1-Day 4.0 mg/L; 10-Day 0.4 mg/L; Lifetime 0.2 mg/L

Drinking water risk studies and risk calculations for a 10-kilogram child

USEPA Residential Soil Screening Level (SSL) 5.3 mg/kg Environmental risk calculations USEPA Industrial SSL 24 mg/kg Environmental risk calculations USEPA Soil-to-Groundwater Risk-Based SSL 9.4x10E-5 mg/kg Environmental risk calculations

USEPA Residential Air Screening Level 0.56 μg/m3 Environmental risk calculations USEPA Industrial Air Screening Level 2.5 μg/m3 Environmental risk calculations USEPA CERCLA Reportable Quantity (RQ) 100 pounds spill trigger reporting level Federal regulatory development OSHA Permissible Exposure Limit (PEL) 100 ppm; or 360 mg/m3 as an 8-hour time

weighted average (TWA) Regulatory rulemaking for worker exposure (Note 1)

Safe Drinking Water Act (SWDA) Maximum Contaminant Level (MCL)

None – Not Established None – Not Established (Note 2)

Note 1: OSHA recommends that employers follow the California OSHA DXA limit of 0.28 ppm, the NIOSH recommended exposure limit of 1 ppm as a 30-minute ceiling, or the American Conference of Governmental Industrial Hygienists (NCGIH) threshold limit value of 20 ppm.

Note 2: DXA is included on the fourth drinking water contaminant candidate list and is included in the Third Unregulated Contaminant Monitoring Rule (EPA 2009; EPA 2016a).

CURRENT STATUS OF DXA TOXICITY ASSESSMENTS HOW CURRENT RISK & GUIDELINE VALUES ARE USED (2,5,6,7)

• Leaches readily from soil to GW, migrates rapidly in GW, and relatively resistant to biodegradation in the subsurface – thus, remedial priority in GW

• Short-lived as a vapor in the atmosphere with estimated 1- to 3-day half-life due to photo-oxidation – concern primarily high vapor concentrations in air

• Short-term exposure may cause eye, nose and throat irritation; long-term exposure may cause kidney and liver damage – risk assessments ongoing (7)

• Does not bio-accumulate, bio-magnify, or bio-concentrate in the food chain • Classified by EPA as “likely to be carcinogenic to humans” by all routes of

exposure (7) • European Union has classified DXA as having limited evidence of carcinogenic

effect (5)

• State agencies in the USA have established “guidelines” or “screening levels” for DXA in environment, particularly for contaminated GW & additional focus on effluent discharges to surface waters, or cleanup levels for GW (5)

• No federal SDWA maximum contaminant level (MCL) has been established for DXA in drinking water – current regulatory focus in USA (2)

(7) US Environmental Protection Agency (USEPA), IRIS Chemical Assessment Tracking System, cfpub.epa.gov/instrac/index.cfm

CURRENT STATUS OF DXA REMEDIAL TECHNOLOGIES Remedial Technology General Options (2,6,7)

• Focus is on GW remediation, although there have been DXA manufacturing site soil removal & disposal programs where known spills have occurred (2)

• Several US DXA remedial GW projects have been operating for years as of 2019 (6)

• DXA remediation in groundwater designed for either ex situ or in situ practice o In situ methods are typically designed to transport contaminated groundwater

to funnel & gate/drains – combined with GW pumping and ex situ destruction methods; followed by GW re-injection as an option • Effective remedial technologies have increasingly been narrowed to those capable

of completely destroying DXA either chemically or thermally (with or without a preliminary physical separation step) • Current effective remedial technologies applied to DXA in the USA include: o Advanced Oxidation Processes (AOP) using UV/peroxide, ozone, other oxidants o Physical Adsorption on ion exchange (IEX) (e.g., AmbersorbTM) or similar

materials (LPGAC) in combination with thermal regeneration (DXA destruction) of spent GAC

o Above technologies in combination with treated GW re-injection, or residual GW treatment in Wastewater Treatment Plants (WWTP)

(6) USEPA (2006) Treatment Technologies for 1,4-Dioxane: Fundamentals and Field Applications, EPA 542-R-06-009, web address: clu-in.org/download/542r06009/pdf

CURRENT STATUS OF DXA REMEDIAL TECHNOLOGIES Remedial Technology General Options – Chem Oxidation + WWTP (3,5)

(5) USEPA (2006) Treatment Technologies for 1,4-Dioxane: Fundamentals and Field Applications, EPA 542-R-06-009, web address: clu-in.org/download/542r06009/pdf

CURRENT STATUS OF DXA REMEDIAL TECHNOLOGIES Remedial Technology Options – Advanced Oxidation Process (AOP’s) • Groundwater can be treated ex situ or in situ using ultraviolet or UV/peroxide,

ozone/peroxide, sodium persulfate, or modified Fenton's reagent (iron/peroxide), collectively referred to as advanced oxidation processes (AOPs) (8, 9 10)

• AOPs also effective for remediating chlorinated volatile organics (CVOCs) that are often found as GW co-contaminants with DXA

• AOPs might require further optimization when applied to sites with CVOCs/related organic contaminants and DXA mixtures owing to the different chemical structures and individual affinities for hydroxyl radicals (9)

o Example: Add’l remediation via mixed physical/biochemical WWTP processes o Example: Add’l processes - air stripping for VOCs; GAC for SVOCs

• Oxidants used in AOP processes are effective proportional to their oxidizing potential as summarized below in Table 3 (6)

(8) Mohr, T. et al. 2010. Environmental Investigation and Remediation: 1,4-Dioxane and Other Solvent Stabilizers. CRC Press (9) Zhang, S. et al. 2017. Advances in bioremediation of 1,4-dioxane-contaminated waters. Journal of Environmental Management 204(2):765-774 (10) DiGuiseppi, W. et al. 2016. 1,4-Dioxane Treatment Technologies. Remediation Journal 27(1):71-92

CURRENT STATUS OF DXA REMEDIAL TECHNOLOGIES Remedial Technology AOP’s – Oxidant Relative Strength (6)

(6) USEPA (2006) Treatment Technologies for 1,4-Dioxane: Fundamentals and Field Applications, EPA 542-R-06-009, web address: clu-in.org/download/542r06009/pdf

Table 3 Relative Oxidative Strength of Common Chemical Oxidants

Oxidant and Reactions (1) Electrode Potential (Eh) (2)

Permanganate

MnO4- + 4 H+ + 3 e- MnO2 + 2 H2O 1.7 V (permanganate ion)

Fenton’s (H2O2 Derived Reactants)

H2O2 + 2 H+ + 2 e- 2 H2O 1.8 V (hydrogen peroxide) 2 ·OH + 2 H+ + 2 e- 2 H2O 2.8 V (hydroxyl radical) ·HO2 + 2 H+ + 2 e- 2 H2O 1.7 V (per-hydroxyl radical) ·O2- + 4 H+ + 3 e- 2 H2O -2.4 V (superoxide radical) HO2- + H2O + 2 e- 3 OH- -0.88 V (hydroperoxide anion)

Ozone

O3 + 2 H+ + 2 e- O2 + H2O 2.1 V (ozone) 2 O3 + 3 H2O2 4 O2 + 2 ·OH + 2 H2O 2.8 V (hydroxyl radical, see rxn 3)

Persulfate S2O82- + 2 e- 2 SO4 2.1 V (persulfate)

·SO4- + e- SO4 -2.6 V (sulfate radical)

(1) Persistence of the oxidant varies depending on site-specific conditions. (2) Reactive species in parentheses; reduction potential is negative.

CURRENT STATUS OF DXA REMEDIAL TECHNOLOGIES Remedial Technology AOP’s – HiPOx Example (11)

(11) APTWater, California Hdq, HiPOx Remedial GW Brochure for 1,4-Dioxane Remediation, undated., www.aptwater.com.

Vendor Claims: • Number of HiPOx systems in use for DXA remediation • Very High Mass Transfer Efficiency (MTE) • High Efficiency Organics Destruction to non-detect levels • Unaffected by Water Turbidity, Color, or Transmissivity • Ozone-Only, AOP, or Combined Operation • Patented Plug-Flow Reactor Design • No soliid waste streams or air emissions generated • Standardized Modular Design • Low Maintenance / Fully-Automated • Flexible design allows adjustments to reagent use with time • No off-spec water discharges • Low relative consumables costs • Does not form THMs, NDMA, or other disinfection byproducts • Robust kill of bacterial and viral pathogens (up to 7 log) • Avoids inherent limitations of UV-based AOP systems when high TSS present in wastewater

APTWater HiPOx AOP System

CURRENT STATUS OF DXA REMEDIAL TECHNOLOGIES Remedial Technology AOP’s – HiPOx Process Flow Diagram (10)

(11) APTWater, California Hdq, HiPOx Remedial GW Brochure for 1,4-Dioxane Remediation, undated., www.aptwater.com.

CURRENT STATUS OF DXA REMEDIAL TECHNOLOGIES Remedial Technology AOP’s – PhotoCat Example (12)

(12) Purifics, London, ON, Canada (2013) Groundwater Remediation Case History: Chemical Free 1,4-Dioxane Purification, Sarasota Florida, 2 p.

Vendor Claims: • Combines best of chemical-free advanced

oxidation processes for DXA remediation • (AOP+®) with high flux continuous flow

silicon carbide ultrafiltration for co-contaminants when needed

• Differences between Photo-Cat AOP+ technology and UV/Chemical AOP is elimination of chemical oxidants

• Highest commercially available AOP+ oxidizing potential

• Treats COCs that chemical-based AOP technologies cannot

• PhotoCat fully automated (no operator required)

• Treats COCs to levels below detection limit • Has no air emissions or solid waste residuals

Purifics PhotoCat Photocatalytic Process Unit

CURRENT STATUS OF DXA REMEDIAL TECHNOLOGIES Remedial Technology AOP’s – PhotoCat Process Flow Diagram (5, 12)

(5) USEPA (2006) Treatment Technologies for 1,4-Dioxane: Fundamentals and Field Applications, EPA 542-R-06-009, web address: clu-in.org/download/542r06009/pdf

CURRENT STATUS OF DXA REMEDIAL TECHNOLOGIES Remedial Technology Options – Adsorption/Thermal Destruction (13)

(13) Water Online News, 2014, ECT2 Breaks New Ground in Treating 1,4-Dioxane, May 2014.

Vendor Claims: • Synthetic resin (e.g., AMBERSORB™ 560)

is a viable treatment option to remove DXA from contaminated GW

• Hydrophobic resin - pore size distribution creates high affinity for organic compounds

• Regeneration of resin - steam heating & condensation of DXA

• Condensate requires separate treatment & disposal (eg, LPGAC use/regeneration)

• Treats COCs (DXA) to levels below detection limit (<0.2 ug/L)

• Competitive costs for hardware and lower operating costs than AOP’s

ECT AmbersorbTM Adsorption & Condensate Extraction Unit

Ambersorb Adsorption Media

CURRENT STATUS OF DXA REMEDIAL TECHNOLOGIES Remedial Technology General Options – Adsorption/Thermal Destruction (14)

(14) ECT2, 2017, Tornatore & Woodard, “Advances in Technologies for Removing PFAS and 1,4-Dioxane From Groundwater”

CURRENT STATUS OF DXA REMEDIAL TECHNOLOGIES Remedial Technology Options – In Situ Options for GW Restoration (2,6, 10,14)

(15) APTWater (2004), PulseOx Case Study: Cooper Drum Superfund Site, CA

Options for GW Extraction: • Key option is GW extraction incorporating

funnel/gate/french drains for ex situ remediation • In Situ Chemical Oxidation (ISCO) is alternative to ex

situ AOP’s – site llithology/geology is important • In Situ thermal GW heating to extract VOC/ SVOC

contaminants where present (eg, DXA) with vapour treatment – has been demonstrated

• In Situ solvent extraction to extract hydrophobic contaminants with other ex situ technologies–for CHCs

• Phytoremediation of DXA using poplar species - has been demonstrated

Options For GW Restoration: • Key option is GW re-injection into contaminated aquifer

after ex situ remedial treatment (eg, AOPs) • Re-injection can be by vertical or horizontal wells,

infiltration gallery, or spray irrigation of treated GW

APTWater PulseOx In Situ AOP GW Remediation (15)

CURRENT STATUS OF DXA REMEDIAL TECHNOLOGIES Remedial Technology General Options

(6) USEPA (2006) Treatment Technologies for 1,4-Dioxane: Fundamentals and Field Applications, EPA 542-R-06-009, web address: clu-in.org/download/542r06009/pdf

FUTURE TRENDS - DXA REMEDIAL TECHNOLOGIES Why is DXA an Emerging Contaminant ? (13)

(13) ECT (2017), “Advances in Technologies for Removing PFAS and 1,4-Dioxane From Groundwater” ECT Brochure.

Note: DXA detection limit continues to decrease to low ppb/high ppt, while permitted discharge limits continue to decrease in surface & GW potable supplies

CURRENT STATUS OF DXA REMEDIAL TECHNOLOGIES Remedial Technology Generalised Cost Options

Table 4 Preliminary Budgetary Cost Estimate for AOP Technology Application

Cost Element 10 GPM Extraction 100 GPM Extraction

CAPX (Manufacture/Transport/Setup/License) $450,000 $ 1, 150,000

CAPX Contingency (AOP Technology Dependent) $225,000 $400,000

OPEX (US$/yr)

Power @ $0.10/KWHr $ 10,406 $ 92029

Oxygen @ $0.60/CCF (HiPOx for ozone gen.) $ 10,557 $105,571

30% Hydrogen Peroxide @ $4.00/gallon $ 6,632 $ 64,391

Total Annual Costs (365 day) $27,595 $ 261,991

Cost per 1000 Gallons $5.25 $5.00

CURRENT STATUS OF DXA REMEDIAL TECHNOLOGIES Remedial Technology Generalised Cost Options Assumptions: • DXA in extracted GW @ 100 mg/L (averaged) and in effluent @ <10 ug/L

(averaged) • Chemical costs for PhotoCat are for H2O2 only • Power cost HiPOx primarily for ozone generation and recovery; PhotoCat

primarily for UV generation • AOP technologies may require front end technology such as air stripping or

ultrafiltration to remove contaminants prior to DXA oxidation, not included • Excludes GW extraction and GW storage costs • O&M excludes Labor and Parts Replacement – add-on of 50% to 100% for

annual labor, and 25% for parts replacement on 5-yr cycle • Contingency for CAPX in range of 30% to 100% depending on technology

selection • Costs in US$ based on 2019 cost indices

Clean Up Conference 2019 Emerging Contaminants Session

9 September 2019

W Gary Smith, PE AECOM USA & Australia

Thank You !!

Questions ??