Office of Solid Waste EPA-542-R-06-009 

and Emergency Response December 2006 

(5203P) www.epa.gov/tio

 http://clu-in.org 

Treatment Technologies for 1,4-Dioxane: 

Fundamentals and Field Applications
CONTENTS 

Section Page 

ACRONYMS AND ABBREVIATIONS..................................................................................................... ii

FOREWORD............................................................................................................................................... iv

NOTICE AND DISCLAIMER .....................................................................................................................v

ACKNOWLEDGMENTS.............................................................................................................................v

EXECUTIVE SUMMARY.....................................................................................................................ES-1

1.0 INTRODUCTION........................................................................................................................ 1-1

1.1 Overview of Dioxane Production and Environmental Occurrence................................. 1-2

1.2 Properties and Behavior of Dioxane in the Environment................................................ 1-3

1.3 Characterization of Dioxane............................................................................................ 1-4

1.4 Cleanup Goals and Standards.......................................................................................... 1-5

2.0 TREATMENT OF MEDIA CONTAINING DIOXANE ............................................................ 2-1

2.1 Treatment Technologies for Dioxane in Water............................................................... 2-1

2.1.1 Advanced Oxidation (Ex Situ)............................................................................ 2-1

2.1.2 Adsorption (GAC) (Ex Situ)............................................................................... 2-5

2.1.3 Bioremediation................................................................................................... 2-5

2.2 Treatment of Dioxane in Soil .......................................................................................... 2-6

2.3 Ongoing Research on Dioxane Treatment ...................................................................... 2-6

3.0 REFERENCES............................................................................................................................. 3-1

APPENDIX A INTERNET SOURCES FOR SUMMARY OF SELECTED U.S. ENVIRONMENTAL 

PROTECTION AGENCY AND STATE GUIDANCE FOR DIOXANE IN SOIL AND 

WATER...........................................................................................................................A-1

EXHIBITS 

Exhibit Page 

1 Process and Product Uses of Dioxane.......................................................................................... 1-2 

2 2002 Toxics Release Inventory Data for Dioxane and 1,1,1-Trichloroethane 

(all amounts in pounds) ................................................................................................................ 1-3 

3 Molecular Structure of Dioxane ................................................................................................... 1-4 

4 Properties of Dioxane and 1,1,1-Trichloroethane ........................................................................ 1-4 

5 Summary of Selected U.S. Environmental Protection Agency and State Guidance for Dioxane in

Soil and Water (as of January 2005) ............................................................................................ 1-6 

6 Process Flow Diagram of a Typical Ozone/Hydrogen Peroxide Groundwater Treatment 

System .......................................................................................................................................... 2-2 

7 Summary of Full- and Pilot-Scale Treatment Projects for 1-4 Dioxane in Groundwater ............ 2-7 

i 
ACRONYMS AND ABBREVIATIONS 

μg/L Micrograms per liter 

AFB Air Force Base 

AOP Advanced oxidation process 

APT Applied Process Technology, Inc. 

ART Accelerated Remediation Technologies, LLC 

atm Atmosphere 

ATSDR Agency for Toxic Substances and Disease Registry 

CLU-IN EPA Hazardous Waste Clean-Up Information Web site 

DCE Dichloroethene 

EPA U.S. Environmental Protection Agency 

FRTR Federal Remediation Technologies Roundtable 

g Grams 

GAC Granular activated carbon 

GC Gas chromatography 

gpm Gallon per minute 

GRAC Groundwater Resources Association of California 

IARC International Agency for Research on Cancer 

IRIS Integrated Risk Information System 

KOW Octanol-water partition coefficient 

L Liter 

Log KOW Log of the octanol-water partition coefficient 

mg Milligrams 

mg/kg Milligrams per kilogram 

mg/kg/day Milligrams per kilogram per day 

mg/L Milligrams per liter 

mg/m3 Milligrams per cubic meter 

mL Milliliter 

mm Hg Millimeters of mercury 

MS Mass spectrometry 

ND Non detect 

NPDES National Pollutant Discharge Elimination System 

OSHA Occupational Safety and Health Administration 

PEL Permissible exposure limit 

ppm Parts per million 

PRG Preliminary remediation goal 

ROD Record of decision 

SERDP Strategic Environmental Research and Development Program 

SIM Selected ion monitoring 

SLAC Stanford Linear Accelerator Center 

ii 
TCA Trichloroethane 

TCE Trichloroethylene 

TRI Toxics Release Inventory 

USACE U.S. Army Corps of Engineers 

USDHHS U.S. Department of Health and Human Services 

UV Ultraviolet 

VOC Volatile organic compound 

iii 
FOREWORD 

1,4-Dioxane is a solvent stabilizer frequently found at contaminated sites where methyl chloroform 

(1,1,1-trichloroethane) was used for degreasing. This report profiles the occurrence and properties of 1,4­

dioxane and provides a summary of the available remedial technologies. The information presented 

should prove useful to project managers and other regulatory officials who oversee cleanup of 

contaminated groundwater, particularly where chlorinated solvents are the principal contaminant. 

Consultants, including hydrogeologists, remediation engineers, and modelers, should also find this report 

useful, as should water utility operators and regulators. 

In recent years, the regulated community has become increasingly aware that 1,4-dioxane is likely to be 

present at sites where methyl chloroform is a contaminant. Although 1,4-dioxane has been a constituent 

of methyl chloroform wastes for decades, recent improvements to analytical methods allowed its 

detection in the parts per billion range beginning in 1997. Analysis of 1,4-dioxane often must be 

specifically requested. The common practice of analyzing by a limited list of available methods for 

regulatory compliance has precluded detection of 1,4-dioxane. 

The properties that made 1,4-dioxane difficult to analyze in the past also make it difficult to treat. For 

example, 1,4-dioxane is fully miscible in water. As a hydrophilic contaminant, it is not, therefore, 

amenable to the conventional ex situ treatment technologies used for chlorinated solvents. Successful 

remedial technologies must take into account the challenging chemical and physical properties unique to 

1,4-dioxane. This report profiles technologies that have been shown to successfully remove or eliminate 

1,4-dioxane and examines other technologies currently under development. 

1,4-Dioxane is among the most mobile organic contaminants in the saturated zone. As a result, it may be 

found farther downgradient than the leading edge of a solvent plume. The combination of a wider spatial 

occurrence and different requirements for treatment technologies make 1,4-dioxane a potentially 

problematic contaminant, particularly if it is discovered after site characterization and remedial design 

have already been completed. In some cases, discovery of 1,4-dioxane has necessitated expanded 

monitoring networks, larger capture zones, and the addition of new treatment technologies to the 

treatment train. 

Treatment Technologies for 1,4-Dioxane: Fundamentals and Field Applications should prove useful to 

all site managers faced with addressing 1,4-dioxane at a cleanup site or in drinking water supplies and to 

those in a position to consider whether 1,4-dioxane should be added to the analytical suite for site 

investigation. 

iv 
NOTICE AND DISCLAIMER 

This report has been funded by the U.S. Environmental Protection Agency (EPA) Office of Superfund 

Remediation and Technology Innovation (OSRTI) under Contract Number 68-W-02-034. Information in 

this report is derived from numerous sources, including personal communications with experts in the 

field. Not all the source documents have been peer reviewed. This report has undergone EPA and 

external review by subject-matter experts. Mention of trade names or commercial products does not 

constitute endorsement or recommendation for use. 

If you have questions about this report, please contact Martha Otto, EPA OSRTI, at (703) 603-8853 or 

otto.martha@epa.gov. 

A portable document format (pdf) version of Treatment Technologies for 1,4-Dioxane: Fundamentals 

and Field Applications may be viewed or downloaded at the Hazardous Waste Clean-up Information 

(CLU-IN) system Web site at http://clu-in.org/542R06009. A limited number of printed copies are 

available free of charge and may be ordered via the Web site, by mail, or by fax from: 

EPA/National Service Center for Environmental Publications 

P.O. Box 42419 

Cincinnati, OH 45242-2419 

Telephone: (800) 490-9198 

Fax: (301) 604-3408 

ACKNOWLEDGMENTS 

Special acknowledgement is given to the federal and state staff and other remediation professionals who 

provided information for this document. Their willingness to share their expertise on treatment 

technologies for 1,4-dioxane encourages the successful application of these technologies at other sites. 

Contributors to the report included EPA OSRTI, EPA Office of Solid Waste, EPA Office of Research and 

Development, EPA Office of Drinking Water, EPA Office of Prevention, Pesticides, and Toxic 

Substances, EPA Office of Emergency Management, EPA Groundwater Forum, Thomas Mohr of the 

Santa Clara Valley Water District of California, Reid Bowman of Applied Process Technology, Inc., John 

Horst of ARCADIS, Charles Drewry of Calgon Carbon Corporation, and Rula Deeb and Christine Cotton 

of Malcolm Pirnie, Inc. Additional acknowledgment is given to Thomas Mohr for authoring the foreword 

to the report. 

v 
EXECUTIVE SUMMARY 

The cyclic ether 1,4-dioxane is a synthetic 

industrial chemical that is used as a solvent in 

products such as paints and lacquers and in 

processes such as organic chemical manufacturing. 

It was used in the past primarily with 1,1,1­

trichloroethane (TCA), as a stabilizer and 

corrosion inhibitor, and has proven to be a 

contaminant of concern (a contaminant that poses 

a human health or environmental risk) at sites 

contaminated with TCA. It is a probable 

carcinogen and has been found in groundwater at 

sites throughout the United States. The physical 

and chemical properties and behavior of 1,4­

dioxane create challenges for its characterization 

and treatment. It is highly mobile and has not 

been shown to readily biodegrade in the 

environment. 

Groundwater investigations at solvent release sites 

have not typically included 1,4-dioxane as a target 

analyte because it was not detectable at low 

concentrations in a standard laboratory scan for 

volatile organic compounds. In addition, it was 

traditionally not regarded as a contaminant of 

concern. As a result, the U.S. Environmental 

Protection Agency (EPA) and many states have 

not promulgated cleanup levels that would 

mandate characterization or remediation of 1,4­

dioxane at contaminated sites. Currently, no 

federal drinking water standard exists for 1,4­

dioxane. Recent analytical improvements, 

however, have now made it possible for 1,4­

dioxane to be detected at concentrations similar to 

other volatile organic compounds. As a result, 

based on a review of the risks posed, some states 

have now established enforceable cleanup goals 

for 1,4-dioxane. For example, in September 2004, 

Colorado became the first state to establish an 

enforceable standard for dioxane in groundwater 

and surface water. This standard is being phased 

in and requires facilities to have met a 6.1 

micrograms per liter (μg/L) limit by March 2005 

and a 3.2 μg/L limit by March 2010. 

This report provides fundamental information 

about 1,4-dioxane and field applications of viable 

treatment technologies to remove this contaminant 

from groundwater. 1,4-Dioxane’s high solubility, 

low potential to partition from the dissolved phase 

Key Findings: 

• 1,4-Dioxane was used primarily in the past as a 

stabilizer in chlorinated solvents. It is now 

used for a wide variety of industrial purposes. 

• 1,4-Dioxane is hydrophilic, is only minimally 

retarded in groundwater, and is not prone to 

sorption to soil. It is a good candidate for 

pump-and-treat remediation using ex situ 

treatment technologies tailored for its unique 

properties. 

• A total of 15 projects were identified where 

1,4-dioxane was treated in groundwater. 

Twelve of the 15 projects used ex situ advanced 

oxidation processes. 

• Research is being conducted on technologies 

such as bioremediation and phytoremediation to 

assess their capability to treat 1,4-dioxane. 

to vapor, and its low affinity for organic matter in 

soil combine to favor its occurrence dissolved in 

groundwater. As a result, treatment of 1,4-dioxane 

in soil is not commonly implemented and sitespecific examples of soil treatment were not 

identified in the research conducted. However, a 

brief discussion is provided on potential 

technologies to treat soil contaminated with 1,4­

dioxane. 

This report focuses on treatment of contaminated 

groundwater. The report includes an overview of 

topics related to 1,4-dioxane, including its 

occurrence, physical and chemical properties, and 

treatability, as well as relevant policy and 

guidance. In addition, site-specific information 

about treatment of 1,4-dioxane is provided, as is 

information on technologies that show promise in 

treating 1,4-dioxane in the future. 

Project managers, technology providers, 

consulting engineers, and members of academia 

can use this information to gain a better 

understanding of current treatment practices and 

the potential for new treatment technologies. This 

report includes information from EPA documents, 

journal articles, conference proceedings, and 

discussions with experts in remediation of 1,4­

dioxane. 

 ES-1 
1.0 INTRODUCTION 

This report provides fundamental information 

about 1,4-dioxane and field applications of 

technologies that can treat this contaminant in 

groundwater. Treatment of soil contaminated with 

1,4-dioxane is also briefly discussed. References 

cited in bold type refer to peer-reviewed journal 

articles. 

Synonyms for 1,4-dioxane are dioxane, p-dioxane, 

diethylene ether, diethylene dioxide, and glycol 

ethylene ether. Dioxane was used primarily as a 

stabilizer in chlorinated solvents, mainly for 1,1,1­

trichloroethane (TCA), and is now used for a wide 

variety of industrial purposes. It stabilizes 

solvents by behaving as a Lewis Base and 

inhibiting reactions of the solvent with acids and 

metal salts that may degrade the properties of the 

solvent. It reacts or complexes with the active 

metal site, preventing degradation of the solvent. 

Dioxane has been added to many grades of TCA at 

2 to 3 percent by volume, and in some instances, 

up to 8 percent (Mohr 2001). 

Dioxane is a probable carcinogen and is found as a 

contaminant in water at sites throughout the 

United States (U.S. Department of Health and 

Human Services [USDHHS] 2002). The physical 

properties and behavior of dioxane, including its 

high mobility and persistence in the environment, 

make characterization and treatment of this 

chemical challenging. Its potential risks as a 

contaminant in groundwater have not been fully 

identified; the U.S. Environmental Protection 

Agency (EPA) and most states have not 

promulgated cleanup levels for dioxane. 

EPA and the International Agency for Research on 

Cancer (IARC) classify dioxane as a Group B2 

(probable human) carcinogen. It has a 

carcinogenic oral slope factor of 1.1E-2 

milligrams/kilogram/day (mg/kg/day) and its 

toxicity is currently being reassessed under the 

EPA Integrated Risk Information System (IRIS) 

(EPA IRIS 2005; IARC 1999). 

In 2001, the Santa Clara Valley Water District of 

California prepared a white paper on solvent 

stabilizers that provided background information 

on dioxane (Mohr 2001). The intent of this report 

is to provide an update to that information, present 

an overview of issues associated with 

characterization and remediation of dioxane, and 

discuss technology applications for treating water 

contaminated with this chemical. More 

information on cleanup of dioxane and links to 

additional resources can be found on the EPA 

Hazardous Waste Clean-Up Information (CLUIN) Web site at http://clu-in.org/contaminantfocus/ 

default.focus/sec/1,4-Dioxane/cat/Overview/. 

1,4-Dioxane Toxicology 

• There is sufficient evidence for the 

carcinogenicity of 1,4-dioxane in experimental 

animals. However, there is inadequate 

evidence in humans for the carcinogenicity of 

1,4-dioxane. Therefore, EPA and IARC have 

classified 1,4-dioxane as a Group B2 (probable 

human) carcinogen (EPA IRIS 2005; IARC 

1999). 

• According to EPA’s IRIS, the carcinogenic risk 

from oral exposure to dioxane is 1.1E-2 

mg/kg/day. 

• The Occupational Safety and Health 

Administration (OSHA) permissible exposure 

limit (PEL)

1 for 1,4-dioxane is 360 milligrams 

per cubic meter (mg/m3

) (OSHA 1998). 

Further information on the toxicology of 1,4­

dioxane can be found on the Web site for the 

Agency for Toxic Substances and Disease Registry 

(ATSDR) 

(http://www.atsdr.cdc.gov/toxprofiles/tp187.html). 

1 PEL is the concentration of a substance to which most 

workers can be exposed without adverse effects averaged 

over a normal 8-hour workday or a 40-hour workweek. 

 1-1 
1.1 Overview of Dioxane Production and 

Environmental Occurrence 

Exhibit 1 lists some of the common process and 

product uses for dioxane. Dioxane may be present 

at sites with TCA contamination because it was 

primarily used as a stabilizer for TCA (Mohr 

2001). TCA frequently occurs in soil and 

groundwater at Superfund and other hazardous 

waste sites in the United States. In addition, the 

relatively high boiling point (101.1o

C) of dioxane 

can increase its concentration in solvents during 

the solvent vapor degreasing process. In one 

study, concentrations of dioxane in spent TCA 

were measured as being nearly 70 percent greater 

than the dioxane concentration in new TCA (2.9 

percent versus 1.7 percent by weight) (Joshi and 

others, 1989). 

Exhibit 1: Process and Product Uses of 

Dioxane 

Process 

Uses 

• Stabilizer in chlorinated solvents 

used for degreasing, electronics 

manufacturing, and metal finishing 

• Solvent for specific applications in 

biological procedures (histology) 

• Solvent used in impregnating 

cellulose acetate membranes used as 

filters 

• Wetting and dispersing agent in 

textile process 

• Solvent used in microscopy 

• Reaction medium solvent in organic 

chemical manufacturing 

• By-product formed during 

esterification of polyester 

Exhibit 1: Process and Product Uses of 

Dioxane (continued) 

Product 

Uses 

• Solvent in paints, lacquer, and 

varnish remover 

• Solvent in stain and printing 

compositions 

• Solvent in liquid scintillation 

counters 

• Surface treating agent for artificial 

leather 

• Impurity in antifreeze, including 

aircraft de-icing fluid formulations 

• Impurity in some consumer products 

(such as deodorants, shampoos, and 

cosmetics) that incorporate 

ethoxylated fatty alcohol sulfates 

• “Inert” ingredient in pesticides and 

fumigants 

• Purifying agent in pharmaceuticals 

• Solvent in resins, oils, rubber 

chemicals, sealants, adhesives, 

waxes, and cements 

Sources: Mohr 2001 and USDHHS 2002 

Information about the occurrence of dioxane in the 

environment is limited. In 2002, based on EPA’s 

Toxics Release Inventory (TRI) data, an estimated 

1.15 million pounds of dioxane were released to 

the environment from facilities that produced, 

processed, or used the chemical in the United 

States (EPA 2003). As shown in Exhibit 2, the 

mass of dioxane released to the environment was 

more than four times the mass of TCA released, 

based on data from the 2002 TRI. Use of TCA 

was greatly reduced after the 1990 Montreal 

Protocol, which restricted emissions of ozonedegrading compounds. Currently, TCA is not 

widely used (Mohr 2005). TRI data serve as a 

general indicator of the amount of a particular 

chemical released to the environment, but should 

not be considered to be a comprehensive measure 

of the quantity released. Not all facilities that 

produce, process, or use a chemical report the 

quantity of its release because of the specific 

reporting requirements for TRI data collection. 

 1-2 
Exhibit 2: 2002 Toxics Release Inventory Data for Dioxane and 1,1,1-Trichloroethane 

(all amounts are in pounds) 

Chemical 

Surface Water 

Dischargesa 

Releases to 

Airb 

Releases to 

Landc 

Off-site 

Releasesd Total Releases 

Dioxane 75,119 105,484 1,902 964,136 1,146,641 

1,1,1-TCA 99 234,013 38,399 1,182 273,693 

Source: EPA 2003 

Notes: a

 Include discharges to streams, rivers, lakes, oceans, and other bodies of water. Include releases from confined sources or open

trenches. Releases caused by runoff are also reportable to TRI under this category. b Include fugitive and point-source emissions. Fugitive emissions include equipment leaks, evaporative losses from surface

impoundments and spills, and releases from building ventilation systems. Point-source air emissions occur through confined air

streams such as stack, vents, ducts, or pipes. c

 Refer to the incorporation of waste into the soil where the waste degrades in the soil. d

 Sum of off-site disposal to Class I underground injection wells, Resource Conservation and Recovery Act Subtitle C landfills, 

and other landfills. 

1.2 Properties and Behavior of Dioxane in 

the Environment 

The compound dioxane is a cyclic ether with a 

chemical formula of C4H8O2 and a molecular 

weight of 88.1. Its two oxygen atoms, each with 

free electrons, make it hydrophilic and miscible 

in water. In addition, it has virtually no dipole 

moment because of its symmetrical structure, as 

shown in Exhibit 3. In its pure form, dioxane is 

a colorless, flammable liquid with a faint odor. 

It is a peroxidizable compound, capable of 

reacting with atmospheric oxygen to form 

potentially explosive peroxides (ATSDR 2004). 

Exhibit 4 summarizes selected properties of 

dioxane and TCA that are relevant to site 

characterization and remediation. Because of its 

properties, dioxane has been shown to migrate 

rapidly in the environment. It can evaporate 

from dry soil, but laboratory column studies 

have shown that dioxane can also rapidly diffuse 

through even low-permeability soils such as silts 

and clays, driven by partitioning into the soil 

moisture as a result of its low octanol-water 

partition coefficient (Kow) (Mohr 2001; Walsom 

and Tunnicliffe 2002). 

Dioxane can migrate rapidly in groundwater and 

will dissolve almost completely because it is 

fully miscible. Once dissolved, the chemical’s 

transport in groundwater is only weakly retarded 

by sorption to soil particles or suspended 

sediments because of its low Kow (Zenker and 

others 2003). In addition, its low Henry’s Law 

constant prevents it from volatilizing from the 

dissolved to the vapor phase. Although it is 

relatively unaffected by sorptive mechanisms in 

an aquifer, dioxane can diffuse into static pore 

water (the pore fraction that does not participate 

in fluid migration), creating the appearance of 

retardation. Depending on the relative volume 

of static to migratory pore water, the resulting 

mass of dioxane that can be stored in the static 

pore water can be significant (Horst 2005). As a 

result, a plume of dioxane can persist after the 

source has been removed or controlled. 

Because of its physical and chemical properties, 

dioxane plumes have been documented to 

measure twice the length of the associated 

solvent plumes and to affect an area up to six 

times greater (Walsom and Tunnicliffe 2002). 

Therefore, defining, capturing, and remediating 

a plume of dioxane in groundwater are 

considerably more challenging than the same 

activities for the associated plume of chlorinated 

solvent (Walsom and Tunnicliffe 2002). 

 1-3 
Exhibit 3: Molecular Structure of Dioxane Exhibit 4: Properties of Dioxane and 1,1,1­

Trichloroethane 

2-Dimensional Structure 

3-Dimensional Structure 

Source: USDHHS 2003 

1.3 Characterization of Dioxane 

As a result of the limitations in the analytical 

methods used for dioxane, it has been difficult to 

evaluate the occurrence of the chemical in the 

environment. Conventional analytical methods 

used by commercial laboratories produced 

sensitivity levels for the chemical that were 

about 100 times greater than those of other 

volatile organic compounds (VOC) because of 

dioxane’s low Henry’s Law constant and vapor 

pressure (Mohr 2001). Routine analysis of 

VOCs uses a purge-and-trap device to separate 

the analytes from the matrix and gas 

chromatography (GC) to identify the analytes. 

Once they have been identified, one of the 

following can be used to quantitate the analytes: 

flame ionization detector (SW-846 Method 

8015) or mass spectrometer (MS) (SW-846 

Method 8260, and water methods 624 and 

1624). 

Property Dioxane 1,1,1-TCA 

Molecular Weight 88.1 133.4 

Melting Point (oC at 

760 mm Hg) 

11.8 -30.4 

Boiling Point (oC at 

760 mm Hg) 

101.1 74.1 

Flash Point (oC at 760 

mm Hg) 

5 to 18 none 

Density (g/mL at 20oC) 1.0329 1.3 

Water Solubility (mg/L 

at 20oC) 

Miscible 950 

Vapor Density (air = 1) 3.03 4.54 

Octanol-Water 

Partition Coefficient 

(KOW) 

0.27 2.49 

Vapor Pressure (mm 

Hg at 20oC) 

30 100 

Henry’s Law Constant 

(atm m3

/mole) 

4.88 x 10-6 0.0172 

Source: CHEMFATE, 2003 

Notes: atm = atmosphere; L = liter; mL = milliliter; 

mm Hg = millimeters of mercury; g = grams; mg = 

milligrams 

For 1,4-dioxane, better sample preparative 

procedures must be used to achieve increased 

sensitivity. Purging at elevated temperatures 

allows more dioxane to be removed from water 

(as described in SW-846 Method 5030C). Use 

of other high temperature sample preparation 

techniques, such as equilibrium headspace 

analysis (SW 846 Method 5021), vacuum 

distillation (SW 846 Method 8261A) (EPA 

2000), and azeotropic distillation (SW 846 

Method 5031) also improve the recovery of 

dioxane. One common variant in analyzing 

dioxane involves improving the sensitivity of the 

MS detector by using selected-ion monitoring 

(SIM) (Lancaster 2003). 

ATSDR provides a general review of the 

available analytical methods for dioxane in all 

media in “Toxicological Profile for 1,4-Dioxane. 

Draft for Public Comment” (ATSDR 2004). 

 1-4 
1.4 Cleanup Goals and Standards 

Currently, there is no federal drinking water 

standard for dioxane. However, several EPA 

regions and states have developed guidance for 

characterizing and remediating dioxane in soil 

and water. In September 2004, Colorado 

became the first state to establish an enforceable 

standard for dioxane in groundwater and surface 

water. This standard is being phased in and 

requires facilities to have met a 6.1 μg/L limit by 

March 2005 and a 3.2 μg/L limit by March 

2010. Three EPA regions and several other 

states also have set screening levels for dioxane 

based on carcinogenic risk; however, these goals 

are not currently enforceable. Drinking water 

action levels and health advisories are often used 

by state regulators to establish appropriate 

cleanup goals, and dioxane is listed in regulatory 

cleanup orders in many states as a result. 

Although a legal or regulatory enforcement level 

is absent in all states except Colorado, dioxane 

can be subject to regulation through cleanup 

requirements (Mohr 2001, 2005). 

Exhibit 5 provides examples of EPA and state 

guidance for dioxane in soil and water. The 

guidance was identified during a review of 

readily available information on the Internet and 

is current as of September 2006. Information 

was available for three EPA regions and 14 

states. Various types of goals are presented, 

including risk-based standards, preliminary 

remediation goals (PRG), and medium-specific 

concentrations. A risk-based goal of 6.1 μg/L 

has been established for dioxane in tap water in 

EPA Regions 3, 6, and 9; however this level 

does not constitute a regulatory standard. 

Exhibit 5 is not intended as a comprehensive 

compilation of federal and state cleanup levels 

for dioxane. Appendix A lists the Internet 

sources used to compile this exhibit. 

GRAC’s Ninth Symposium in its Series on 

Groundwater Contaminants – 1,4-Dioxane and 

Other Solvent Stabilizer Compounds in the 

Environment 

In December 2003, the Groundwater Resources 

Association of California (GRAC) held a 

symposium in San Jose, California, on 1,4­

dioxane and other solvent stabilizer compounds 

in the environment. The symposium addressed 

the following issues: 

• Nature and extent of 1,4-dioxane occurrence 

in the environment 

• Survey of 1,4-dioxane occurrence at solvent 

release sites in the San Francisco Bay area 

• Case studies of the Pall-Gelman Sciences site 

and the Stanford Linear Accelerator site 

• Updated evaluation of the carcinogenic 

potential of 1,4-dioxane 

• Biological treatment options, in situ reactive 

zone strategies, and in-well air stripping for 

1,4-dioxane removal 

• Ozone-peroxide advanced oxidation 

treatment of 1,4-dioxane in water 

• Legal aspects of emerging contaminants 

A synopsis of some of the presentations at the 

symposium is available at the following Web site: 

http://www.grac.org/dioxanemain.html. 

 1-5 
Exhibit 5: Summary of Selected U.S. Environmental Protection Agency and State Guidance for Dioxane in Soil and 

(as of September 2006) 

EPA Region 

or State Type of Guidance Matrix Concentration 

Region 3 Risk-Based Concentrations 

Tap Water 6.1 μg/L Soil 

260 mg/kg (Industrial) 58 mg/kg (Residential) 0.0013 to 0.0026 mg/kg (Groundwater Pr

Region 6 Human Health Medium-Specific Screening Levels 

Tap Water 6.1 μg/L Soil 170 to 520 mg/kg (Industrial) 44 mg/kg (Residential) 

Region 9 Preliminary Remediation Goals 

Tap Water 6.1 μg/L Soil 160 mg/kg (Industrial) 44 mg/kg (Residential) 

Arizona Soil Remediation Levels Soil 1,700 mg/kg (Nonresidential) 400 mg/kg (Residential) 

California Health-Based Advisory Levels Drinking Water 3 μg/L Soil 0.0018 mg/kg (Residential and Industrial) 

Colorado Water Quality Standard Groundwater and Surface Water 6.1 μg/L by March 2005; 3.2 μg/L by Ma

Delaware Uniform Risk-Based Remediation Standards (Guidance) Groundwater 6 μg/L Soil 0.6 mg/kg (Critical Water Resource Area) 58 to 520 mg/kg (Non-critical Water Reso

Florida Soil Cleanup Target Levels Soil 

38 mg/kg (Direct Exposure – Commercia23 mg/kg (Direct Exposure – Residential) 0.01 mg/kg (Leachability – Groundwater) 0.5 mg/kg (Leachability – Surface Water) 

Groundwater 3.2 μg/L 

Iowa Standard for Soil Soil 280 mg/kg (Statewide Standard) 

Maine Maximum Exposure Guideline Drinking Water 32 μg/L 

Michigan Generic Cleanup Criteria and Screening Levels Drinking Water 350 μg/L (Industrial) 85 μg/L (Residential) 

Soil 

7 mg/kg (Drinking Water Protection – Ind56 mg/kg (Groundwater – Surface Water 2,400 to 3,400 mg/kg (Direct Contact – In34,000 mg/kg (Groundwater Contact Prot

 1-6 
Exhibit 5: Summary of Selected U.S. Environmental Protection Agency and State Guidance for Dioxane in Soil and 

(as of September 2006) (continued)

EPA Region 

or State Type of Guidance Matrix Concentration 

56 mg/kg (Groundwater – Surface Water 530 mg/kg (Direct Contact – Residential) 34,000 mg/kg (Groundwater Contact – Re1.7 mg/kg (Drinking Water Protection – R97,000 mg/kg (Soil Saturation Concentrat

Missouri Target Concentrations 

Groundwater 3 μg/L Soil 150 to 590 mg/kg (Direct Exposure) 0.01 mg/kg (Leaching to Groundwater) 

Pennsylvania Medium-Specific Concentrations for Organic Regulated Substances in Groundwater 

Groundwater 

5.6 μg/L (Used Aquifers – Residential) 24 μg/L (Used Aquifers – Nonresidential) 56 μg/L (Nonuse Aquifers – Residential) 240 μg/L (Nonuse Aquifers – Nonresiden

Soil 

210 to 240 mg/kg (Direct Contact – Nonr0.31 to 240 mg/kg (Groundwater Protecti41 mg/kg (Direct Contact – Residential) 0.0073 to 56 mg/kg (Groundwater Protect

South Carolina Drinking Water Regulation and Health Advisory Drinking Water 70 μg/L (Monthly average) 

Texas Protected Concentration Levels 

Groundwater 18.6 μg/L (Commercial/Industrial) 8.3 μg/L (Residential) Soil 

2,600 mg/kg (Total Combined Pathways – 0.36 mg/kg (Groundwater Protection – In

552 mg/kg (Total Combined Pathways – 0.083 mg/kg (Groundwater Protection – R

Soil 290 to 29,000 mg/kg (Industrial) 1,000 to 100,000 mg/kg (Residential) 

West Virginia Risk-Based Concentrations 

Groundwater 6.1 μg/L 

Soil 5,200 mg/kg (Industrial) 58 mg/kg (Residential) 

Wyoming Soil Cleanup Level Soil 44 mg/kg (Residential) 

Source: Internet sources reviewed in September 2006. (Appendix A lists the Internet sources used to compile this summary.) Notes: mg/kg = milligrams per kilogram μg/L= micrograms per liter  1-7 
2.0 TREATMENT OF MEDIA 

CONTAINING DIOXANE 

The physical and chemical properties of dioxane 

discussed in Section 1.0 create challenges for 

removing this compound from water. Dioxane is 

well suited to removal by groundwater extraction 

because of its high solubility and low degree of 

partitioning to organic matter in soil. However, 

the relatively low Henry’s Law constant of 

dioxane makes technologies such as air stripping 

generally ineffective in treating the chemical in 

water. Its low adsorptive capacity also limits the 

effectiveness of treatment by granular activated 

carbon (GAC), although one full-scale GAC 

application was identified. As discussed in 

Section 1.0, bench-scale studies indicate that 

biodegradation of dioxane is possible, but 

information on field applications of this 

technology is limited (Zenker and others 2003). 

Technologies that are effective for treating 

chlorinated solvents are often ineffective for 

treating dioxane because the properties of dioxane 

differ from those of chlorinated solvents. To date, 

the number and types of technologies available to 

treat dioxane are limited; however, research is 

under way to test and evaluate additional treatment 

technologies for this contaminant. This report 

provides information about three technologies that 

have been used to treat dioxane at the pilot and full 

scale levels: 

• Advanced oxidation (ex situ) 

• Adsorption (GAC) (ex situ) 

• Bioremediation 

As discussed previously, dioxane in soil tends to 

readily partition to groundwater and does not sorb 

to soil particles. Therefore, groundwater is the 

primary medium of concern for this contaminant. 

The following sections present information about 

technologies applicable for treating dioxane and 

include site-specific examples where available. 

Section 2.1 addresses full- and pilot-scale 

treatment applications for dioxane in water; 

Section 2.2 briefly discusses potential technologies 

for treating dioxane in soil; and Section 2.3 

presents information on research in bioremediation 

and phytoremediation. 

2.1 Treatment Technologies for Dioxane in 

Water 

This section discusses applications of advanced 

oxidation (ex situ), GAC adsorption (ex situ), and 

bioremediation to treat dioxane in water. 

2.1.1 Advanced Oxidation (Ex Situ) 

Advanced oxidation processes (AOP) are 

commercially available for aboveground treatment 

of dioxane in water. The technology can be used 

independently or as a pre- or post-treatment step in 

a remediation process. AOPs use hydroxyl 

radicals, which are powerful oxidizers, to 

sequentially oxidize organic contaminants to 

carbon dioxide, water, and residual chloride (Mohr 

2001; Berman and others 1998; Walsom and 

Tunnicliffe 2002). Two common AOPs include 

hydrogen peroxide with ultraviolet (UV) light, and 

hydrogen peroxide with ozone. UV light causes 

the release of hydroxyl radicals from hydrogen 

peroxide added to contaminated water. Hydroxyl 

radicals are also generated when ozone is mixed 

with hydrogen peroxide, even in the absence of 

UV light, as shown in the equation below. 

2O3 + H2O2 = 2yOH + 3O2 

Other AOPs include hydrogen peroxide with 

ferrous iron (Fenton’s reagent) and ozone with UV 

light. However, no sites where these processes 

have been used for dioxane treatment were 

identified in the research conducted for this report. 

Exhibit 6 shows a process flow diagram of a 

typical ozone/hydrogen peroxide groundwater 

treatment system. 

Hydrogen Peroxide with UV Light 

Four projects were identified that used an AOP 

system that consisted of UV light for treatment of 

dioxane. The four projects were conducted at full 

scale at the following sites: McClellan Air Force 

Base (AFB) in Sacramento, California; Gloucester 

Landfill in Ontario, Canada; Charles George 

Landfill in Tyngsborough, Massachusetts; and the 

Pall-Gelman Sciences site in Ann Arbor, 

Michigan. Full-scale remediation of dioxane in 

groundwater was conducted at McClellan AFB in 

California using an AOP system consisting of 

 2-1 
hydrogen peroxide and UV light. The system was system was restarted in October 2003 and treated 

originally installed to treat vinyl chloride approximately 2.7 million gallons of groundwater 

contamination and was shut down after each month. The system reduced the 

concentrations of vinyl chloride dropped below the concentrations of dioxane to below the EPA 

maximum contaminant level. The system was Region 9 tap water PRG of 6.1 μg/L and is no 

then tested to evaluate whether it was capable of longer in operation (Zabaneh 2004; Gronstal 

treating dioxane and it proved effective. The 2006). 

Exhibit 6: Process Flow Diagram of a Typical Ozone/Hydrogen Peroxide Groundwater Treatment 

System 

Source: Federal Remediation Technologies Roundtable (FRTR) 2006 

An AOP consisting of hydrogen peroxide and UV 

light is being used to treat dioxane in groundwater 

at the Gloucester Landfill site in Ontario, Canada. 

The site served as a municipal waste dump from 

approximately 1957 to 1980 and as a disposal area 

for federal laboratory, university, and hospital 

wastes from 1969 to 1980. Chemicals from the 

wastes seeped into the groundwater, contaminating 

a shallow, unconfined aquifer and a deep, confined 

aquifer. A 29-well pump-and-treat system has 

been operated at the site since 1992 to contain the 

contaminant plume and remove the contaminant 

mass from the aquifers. The system pumps and 

treats approximately 132 gallons per minute (gpm) 

from the deep aquifer and 61 gpm from the 

shallow aquifer. The extracted groundwater is 

treated at the site using the following process: 

adding acid to the influent groundwater to reduce 

the pH to an optimal level for treatment, passing 

the groundwater through a series of UV lamps in 

the presence of hydrogen peroxide to destroy 

target contaminants, and adding sodium hydroxide 

to raise the pH again (the exact pH value was not 

provided). After sodium hydroxide has been 

added, the treated groundwater is reinjected at one 

or more of five locations upgradient of the site. 

 2-2 
Pall-Gelman Sciences Site – UV Light and 

Hydrogen Peroxide Treatment System Details 

A treatment system using UV light and hydrogen 

peroxide was applied at the Pall-Gelman Sciences 

site. Eighteen purge wells, including a 4,479-foot 

long horizontal well, were used to extract and divert 

groundwater. Purged water was mixed with 

sulfuric acid (a 93 percent solution by volume) in a 

lined pretreatment pond known as the “Red Pond” 

to lower the pH to 3.8. Earlier studies showed a pH 

of 3.8 to be optimal for hydrogen peroxide chemical 

reactions in conjunction with UV light. 

In the first step of treatment, a 50 percent hydrogen 

peroxide solution was injected into the treatment 

line and mixed with groundwater by a static mixer. 

Water then passed through a multiple-chamber UV 

system consisting of 22 lamps, where it was 

exposed to UV radiation for approximately 5 

seconds. After UV and hydrogen peroxide 

treatment, the pH of the treated water was raised to 

approximately 6.9 by adding sodium hydroxide (40 

percent by volume) to meet the surface water 

discharge requirement of 6.5 to 9.0. Sodium 

bisulfate also was added to remove excess hydrogen 

peroxide before the water was discharged to an onsite holding pond known as the “Green Pond.” The 

water was monitored daily to ensure compliance 

with state requirements before it was released into 

an unnamed tributary of Honey Creek, which flows 

into the Huron River. 

Large volumes of reactive chemicals were required 

for treating groundwater using the UV and 

hydrogen peroxide treatment system. The electrical 

demand also was high, averaging $850 per day. 

The overall treatment cost for the system was 

approximately $3.50 per 1,000 gallons. For these 

reasons, the site owner converted the UV and 

hydrogen peroxide system to an ozone and 

hydrogen peroxide-based technology in 2005 to 

reduce hydrogen peroxide consumption by 50 

percent and eliminate the need for sulfuric acid and 

sodium hydroxide. Treatment costs using this new 

system were anticipated to be approximately 

$1.50/1,000 gallons (Brode and others 2005). 

Performance data for the system were not 

available (Ludwig 1997). 

An AOP consisting of UV-hydrogen peroxide 

oxidation was used to treat landfill leachate and 

contaminated groundwater at the Charles George 

Landfill, a Superfund site in Massachusetts. The 

contaminated liquid was extracted downgradient 

of the capped landfill and pumped to a 3.6­

million-gallon storage lagoon, where it was 

treated. Initial concentrations of dioxane in the 

liquid were not provided; however, the system was 

able to reduce the concentration to 7 μg/L to meet 

the standard for surface water discharge specified 

in the record of decision (ROD) (U.S. Army Corps 

of Engineers [USACE] 2004). 

Dioxane was unintentionally released into the 

subsurface in the 1960s at the Pall-Gelman 

Sciences site in Michigan. The source of the 

contamination was a manufacturer of microporous filters. The manufacturer used dioxane as 

a solvent for cellulose acetate, which was a 

component of specific membrane filters made at 

the site. The chemical was released into the 

subsurface primarily through a state-permitted, 

unlined treatment pond that was used to treat and 

dispose process wastes. Dioxane was eliminated 

from the manufacturing process in the mid-1980s 

(GRAC 2003). Groundwater samples collected at 

that time contained concentrations of dioxane as 

high as 221,000 μg/L. 

Dioxane migrated into a complex sequence of 

glacial outwash deposits that form highly 

transmissive aquifers at the site. Once it reached 

these aquifer systems, the dioxane migrated more 

than 2 miles from the source areas in multiple 

plumes. This release constituted one of the 

nation’s largest releases of dioxane to groundwater 

(Tetra Tech EM Inc. [Tetra Tech] 2003). 

Groundwater at the Pall-Gelman Sciences site was 

routinely monitored at 50 to 100 locations. 

Treatment system influent concentrations ranged 

from 3,000 to 4,000 μg/L and effluent 

concentrations ranged from nondetect to 10 μg/L. 

The method detection limit was 1.0 μg/L. 

Although treatment has only slightly reduced the 

areal extent of the plumes, 2 billion gallons of 

groundwater have been purged, treated, and 

discharged since 1997, and more than 60,000 

pounds of dioxane have been removed from the 

contaminated aquifers. The concentration of 

dioxane within the plumes has also decreased. 

(GRAC 2003; Brode and others 2005). 

 2-3 
Hydrogen Peroxide with Ozone 

Eight projects that involved the treatment of 

dioxane in groundwater at five sites using a 

hydrogen peroxide-and-ozone-based system 

(HiPOx) were identified. A full-scale HiPOx 

system was built and installed as a pre-treatment 

step to remove dioxane and reduce chlorinated 

solvent concentrations in the contaminated 

groundwater at a confidential site in South El 

Monte, California. Initially, the system was 

operated using one well at 500 gpm and used three 

ozone injectors with 8-inch, static mixers. Later, a 

second well was added and the system flow rate 

was increased to 1,000 gpm. The system lowered 

the dioxane concentration from 4.6 μg/L in the 

influent to less than 1 μg/L in the effluent. The 

analytical method that was used was not specified 

(Bowman and others 2003; GRAC 2003). 

Dioxane was found in extraction wells that fed an 

air stripper that was already in operation to remove 

chlorinated solvents from groundwater at a 

confidential site in City of Industry, California. 

Pilot tests showed that the HiPOx system could 

reduce the concentration of dioxane from 610 

μg/L in the influent to 9.5 μg/L in the effluent 

(Bowman and others 2003). Pilot data were used 

to configure a commercial-scale unit that reduces 

the influent concentration of dioxane of 320 μg/L 

to an effluent concentration below the detection 

limit of 1 μg/L. The analytical method that was 

used was not specified. The commercial unit was 

installed in February 2002 and operates at a flow 

rate of 45 gpm (Bowman and others 2003; GRAC 

2003; Applied Process Technology, Inc. [APT], 

2005a). 

The concentration of dioxane in the effluent from 

an air stripping and carbon adsorption treatment 

system was 15 μg/L, while the statutory discharge 

limit was 5 μg/L at the Middlefield-Ellis-Whisman 

Superfund Site in Mountain View, California. The 

air stripper and GAC system were replaced with a 

50-gpm HiPOx unit that began operation in 

December 2003. The concentration of dioxane in 

the system effluent has been consistently reduced 

to below the detection limit of 1 μg/L. As of 

October 2006, the effluent concentration remains 

non-detect. The analytical method used was EPA 

Method 8270-SIM (Boarer and Milne, 2004). 

Carbon adsorption and air stripping systems were 

in place to treat tetrachloroethene and TCA at a 

confidential industrial site in the Pacific 

Northwest. In 2002, dioxane was discovered at 

levels of up to 200 μg/L. A 20-gpm HiPOx unit 

was installed in April 2003 as a post-treatment to 

the carbon system and air stripper. The 

concentration of dioxane in the effluent has been 

reduced to below 6 μg/L (APT 2005b). 

A treatment train that consisted of GAC and an 

undisclosed treatment system removed chlorinated 

solvents from groundwater at an industrial site in 

Orange County, California. In addition, a 

coagulation step was used to meet discharge 

requirements for suspended solids at the site. In 

2003, dioxane was detected at concentrations of 

approximately 170 μg/L. The National Pollutant 

Discharge Elimination System (NPDES) permit at 

this site called for reduction of dioxane to below 3 

μg/L. A 10-gpm mobile HiPOx field 

demonstration unit was used in tests on site. The 

demonstration showed that the dioxane could be 

reduced to meet the 3 μg/L permit requirement 

and a stationary 10-gpm HiPOx unit was installed 

in March 2004. The HiPOx unit is currently in 

operation and is reducing the concentration of 

dioxane to below 3 μg/L, and is also reducing 1,1­

dichloroethylene (DCE) at 8 μg/L and 

trichloroethene (TCE) at 3 μg/L each to below 1 

μg/L. The GAC system was retained at the 

effluent of the HiPOx system to remove other 

VOCs, such as TCA. The coagulation step was 

also retained (APT 2005c). The performance data 

for the Middlefield-Ellis-Whisman Superfund site 

and the industrial site in Orange County, 

California, do not appear to indicate a relationship 

between the flow rate of the HiPOx system and the 

reduction in contaminant concentrations achieved. 

Further research is required to better understand 

the effect of the system flow rate on treatment 

efficiency. 

Limitations of AOPs 

Although AOPs are capable of reducing the 

concentration of dioxane, potential limitations 

need to be considered before the technology can 

be implemented. Some of these limitations are 

listed below: 

 2-4 
• If the dioxane-contaminated water contains 

bromide, ozone will oxidize it to bromate. 

IARC has classified bromate as a Group B2 

(probable human) carcinogen. Therefore, the 

potential to form bromate must be considered 

and the production of bromate should be 

reduced as much as possible. These 

reductions may be achieved by adding 

ammonia or by decreasing the pH (Horst 

2005). 

• The potential formation of AOP 

decomposition products such as aldehydes and 

organic acids (Burgess 2005). 

• If UV light is used as part of the oxidation 

process, the aqueous stream being treated must 

provide for good transmission of the light; 

high turbidity interferes with the oxidation 

reaction and should be reduced before 

treatment (FRTR 2006). 

• Advanced oxidation reactions rely on contact 

between the oxidant and contaminant, which 

can limit the ability of the oxidation system to 

handle contaminant concentrations 

significantly above 1 milligram per liter 

(mg/L) without multiple units in series (Horst 

2005) 

• Free radical scavengers (for example, 

hydroxyl scavengers such as carbonate and 

bicarbonate) can inhibit contaminant 

destruction efficiency (Horst 2005; FRTR 

2005). 

2.1.2 Adsorption (GAC) (Ex Situ) 

Adsorption involves concentrating contaminants 

on the surface of a sorbent such as GAC, thereby 

reducing the concentration of those contaminants 

in the liquid being treated. GAC was used to treat 

solvents in groundwater at the Stanford Linear 

Accelerator Center (SLAC) site in Menlo Park, 

California, before dioxane was discovered. It was 

later found that dioxane was present in the 

groundwater at concentrations ranging from a few 

μg/L to 1,000s of μg/L. The concentration of 

dioxane was the highest at the location of a former 

underground storage tank (reported as high as 

7,300 μg/L). Adsorption using GAC was found to 

remove the dioxane despite expectations based on 

the properties of the contaminant. Analytical 

results of influent and effluent water samples 

collected from the treatment system showed that 

although the influent water has historically 

contained dioxane at concentrations as high as 

1,500 μg/L, the compound was not present in the 

effluent water samples analyzed. The unexpected 

result could be attributed to low influent 

concentrations to the treatment system, very low 

flow rates (0.5 gpm), or possible biodegradation of 

dioxane on carbon surfaces in the presence of 

tetrahydrofuran, another constituent of the influent 

to the GAC (GRAC 2003). 

2.1.3 Bioremediation 

Ex situ bioremediation of groundwater involves 

putting contaminants in the extracted groundwater 

in contact with microorganisms in attached or 

suspended growth biological reactors. Ex situ 

bioremediation was selected to treat dioxane in 

groundwater at the Lowry Landfill Superfund site 

near Denver, Colorado. Between 1960 and 1980, 

the site was used for co-disposal of industrial and 

municipal solid wastes. Industrial waste liquids 

that contained spent solvents, which included 

dioxane, were placed in unlined pits and 

subsequently contaminated shallow groundwater. 

The ROD issued for the site required collection 

and treatment of landfill leachate and shallow 

groundwater emanating from the landfill mass. 

Numerous treatability studies were conducted to 

evaluate potential treatment options for dioxane in 

the collected groundwater. A fixed-film, 

biological process was pilot tested in a continuousflow configuration using Kaldnes media at 

temperatures of 15°C and 25°C. Kaldnes is a 

buoyant plastic media engineered in a wheel 

shape, allowing a small amount of water flow to 

circulate the media throughout the vessel. The 

pilot system successfully treated between 0.4 and 

0.7 gpm of extracted groundwater that contained 

8,000 to 12,000 μg/L of dioxane; the effluent 

concentrations were less than 200 μg/L. Similar 

results were obtained at both temperatures. 

Extensive testing indicated that dioxane was 

degraded as a co-metabolite in the presence of 

tetrahydrofuran (Zenker and others 2000). A fullscale, fixed-film, moving-bed, biological treatment 

system was deployed at the site in December 2003 

(GRAC 2003). Performance data for the full-scale 

system were not available in the references used 

for this report. 

 2-5 
Exhibit 7 at the end of Section 2.0 summarizes 15 

projects for the treatment of dioxane in 

groundwater. The timeframe for the projects 

(where this information was provided) ranges from 

July 1998 to the present. 

2.2 Treatment of Dioxane in Soil 

Dioxane typically migrates through soil rapidly 

and enters groundwater because it has a relatively 

high solubility and boiling point and a low log Kow 

and Henry’s Law constant. When it is present in 

soil, however, its physical properties indicate that 

it is theoretically volatile enough to be removed in 

situ using soil vapor extraction or ex situ with 

thermal desorption, even though its vapor pressure 

is lower than many VOCs. A factor to consider if 

a soil vapor extraction system is used is that 

dioxane will likely partition to the soil pore water 

in the vadose zone. The system should therefore 

be able to eliminate soil moisture to be effective 

(Horst 2005). Dioxane should also theoretically 

be amenable to removal from soil in situ or ex situ 

using cosolvent extraction with water as a solvent 

because of its hydrophilic characteristic. No fullor pilot-scale projects that involved treatment of 

dioxane in soil were identified from the sources 

reviewed for this report. 

2.3 Ongoing Research on Dioxane Treatment 

Research is being conducted on various 

technologies to assess whether they are capable of 

treating dioxane. These technologies include 

bioremediation using various strains of bacteria 

and phytoremediation. 

The primary evidence for biodegradation of 

dioxane is from aerobic systems. Biodegradation 

pathways can be broken down into two categories: 

1. Metabolic degradation (where dioxane serves 

as the primary growth substrate); at least four 

bacterial species are known to metabolically 

degrade dioxane under aerobic conditions: 

Amycolata sp. Strain CB1190, Mycobacterium 

vaccae, and two strains of Rhodococcus sp. 

2. Cometabolic degradation (where dioxane is 

not the primary growth substrate but is 

degraded in the presence of other metabolites); 

examples include degradation in the presence 

of a structural analog, such as tetrahydrofuran 

(Horst 2005). 

In addition to the pilot-scale bioremediation 

project described in Section 2.1.3, a bench-scale 

study was conducted to evaluate the ability of a 

Amycolata sp. Strain CB1190, to degrade dioxane 

in industrial sludge obtained from a site in 

Darlington, South Carolina. CB1190 was able to 

degrade dioxane at a rate of 0.33 mg of 

dioxane/minute/mg of protein and mineralize 59.5 

percent of the dioxane to carbon dioxide. This rate 

of degradation indicates that CB1190 has the 

potential to contribute to a practical and 

economical process for bioremediation of dioxanecontaminated groundwater and waste streams 

(Parales and others 1994). 

In another bench-scale bioremediation study, 

bacterial inocula were isolated from dioxanecontaminated groundwater obtained from a 

Massachusetts Brownfields site. The bacteria 

were enriched using standard microbiological 

subculturing techniques, and the enrichment serum 

bottles were incubated under butane for a 4-week 

period. A microcosm study of the bottles 

indicated that butane was consumed and that 

dioxane was degraded from concentrations as high 

as 7.7 mg/L to sub-μg/L concentrations within a 

48-hour period as a result of the biostimulation. 

Butane biostimulation enhances contaminant 

destruction by encouraging the naturally occurring 

bacteria that are already acclimated to site 

conditions to flourish. This study demonstrates 

the potential for bioremediation of dioxane using 

butane biostimulation (GRAC 2003). 

The ability of bioremediation to address dioxane 

contamination is being evaluated in various other 

bench-scale studies. Some of these studies are 

being funded by the Strategic Environmental 

Research and Development Program (SERDP) and 

are aimed at developing a mechanistic 

understanding of the enzymes, pathways, and 

kinetics of dioxane biodegradation; identifying 

and isolating new dioxane degrading microbes; 

identifying the products of dioxane biodegradation 

by studying degradation pathways in pure bacterial 

cultures; and confirming that the same 

biodegradation pathways occur in active 

environmental samples (Steffan 2005; AlvarezCohen 2005). 

 2-6 
Exhibit 7: Summary of Full- and Pilot-Scale Treatment Projects for Dioxane in Groundwater 

Site Name, Location 

Initial 

Contaminant 

Concentration 

(μg/L)1 

Final 

Contaminant 

Concentration 

(μg/L) 1 Scale Technology 

Period of 

Operation 

Cleanup Goal 

(μg/L) 

Ope

Param

Advanced Oxidation Processes (AOP) (Ex Situ) WP 68, McClellan AFB, Sacramento, CA 

64.1 (samples collected in September 2004) 

16.5 (samples collected in September 2004) < 6.1 (samples collected after September 2004) 

Full UV-hydrogen 

peroxide 

October 2003 to date unknown 

6.1 (EPA tap water PRG) 

NA 

Gloucester Landfill, Ontario, Canada 

NA NA Full UV-hydrogen 

peroxide 

1992 to present 

NA Addition o

reduce pHgroundwaseries of Upresence operoxide; caustic to pH 

Charles George Landfill, Tyngsborough, MA 

NA 7 Full UV-hydrogen 

peroxide 

NA NA NA 

Pall-Gelman Sciences, Ann Arbor, MI 

3,000 to 4,000 ND to 10 Full UV-hydrogen 

peroxide 

NA NA Addition o

lower pH; with 50 pehydrogen solution; pgroundwaseries of Uaddition oincrease p

Confidential Site, South El Monte, CA 

20.2 < 2 Pilot HiPOx (ozone + 

hydrogen peroxide) pre-treatment for air stripping 

July to August 1998 

< 3 9.4 ppm o

ppm hydroperoxide; system 

2-7 
Exhibit 7: Summary of Full- and Pilot-Scale Treatment Projects for 1,4-Dioxane in Groundwater (continued) 

Site Name, Location 

Initial 

Contaminant 

Concentration 

(μg/L)1 

Final 

Contaminant 

Concentration 

(μg/L) 1 Scale Technology 

Period of 

Operation 

Cleanup Goal 

(μg/L) 

Ope

Param

4.6 0.85 Full HiPOx (ozone + 

hydrogen peroxide) pre-treatment for air stripping 

August 2000 to September 2004 

< 3 3.1 ppm o

ppm hydroperoxide; system (prstep for Gtreatment) 

Confidential Site, City of Industry, CA 

610 9.5 Pilot HiPOx (ozone + 

hydrogen peroxide) pre-treatment for air stripping 

August 2000 to January 2001 

< 3 NA 

320 <0.95 Full HiPOx (ozone + 

hydrogen peroxide) post-treatment for air stripping 

February 2001 to present 

< 3 70 gpm at 

eventually 50 gpm 

Middlefield-EllisWhisman Superfund Site, Mountain View, CA 

15 < 0.94 Full HiPOx (ozone + 

hydrogen peroxide) 

December 2003 to present 

5 (statutory discharge limit) 

50 gpm 

Confidential Site, Pacific Northwest 

200 < 6 Full HiPOx (ozone + 

hydrogen peroxide) post- treatment for carbon and air stripping 

April 2003 to present 

< 6 20 gpm 

Confidential Site, Orange County, CA 

170 < 3 Pilot HiPOx (ozone + 

hydrogen peroxide) 

January 2004 

< 3 10 gpm 

Full HiPOx (ozone + 

hydrogen peroxide) pre-treatment for GAC 

March 2004 to present 

GAC Adsorption SLAC, Menlo Park, CA (Former Underground Storage Tank Area) 

7,300 NA Full GAC NA NA NA 

2-8 
Exhibit 7: Summary of Full- and Pilot-Scale Treatment Projects for 1,4-Dioxane in Groundwater (continued) 

Site Name, Location 

Initial 

Contaminant 

Concentration 

(μg/L)1 

Final 

Contaminant 

Concentration 

(μg/L) 1 Scale Technology 

Period of 

Operation 

Cleanup Goal 

(μg/L) 

Ope

Param

Bioremediation Lowry Landfill Superfund Site, Aurora, CO 

8,000 to 12,000 < 200 Pilot Bioremediation 

(fixed film bioreactor using Kaldnes media) 

NA NA NA 

NA NA Full 

Notes: 1 Based on available data, initial and final contaminant concentrations for projects with treatment trains may be for the entire train or for technologies within th

dioxane. NA = Not available in information reviewed ND = Nondetect gpm = Gallons per minute ppm = Parts per million 

2-9 
A study of the relationship between enhancing 

biodegradability and oxidizing dioxane using 

ozone and hydrogen peroxide showed a linear 

correlation. The initial dioxane solutions 

exhibited negligible or near-zero biological 

oxygen demand (an indicator of biodegradation) 

with the biological seed employed. This finding 

confirmed that dioxane is not readily 

biodegradable and may not be removed effectively 

using conventional biological methods. The 

concentration of dioxane in the solution decreased 

and biological oxygen demand increased with each 

treatment of ozone and hydrogen peroxide, 

indicating partial oxidation of dioxane and 

transformation of this compound into more 

biodegradable intermediates (Suh and Mohseni 

2004). 

Phytoremediation has also been investigated to 

assess its suitability for removing dioxane in 

groundwater. Phytoremediation as it applies to 

dioxane is a relatively new remedial approach, and 

many of the associated removal and degradation 

pathways are being studied. Phytoremediation 

relies on multiple processes to remove 

contaminants from groundwater. Examples 

include the uptake of contaminated water, after 

which dioxane may be metabolized or volatilized 

from plant leaves (phytovolatilization), and the 

biodegradation of dioxane in the rhizosphere (root 

zone). 

Papers published on the potential for 

phytoremediation of dioxane have evaluated the 

usefulness of various plants and trees, such as 

hybrid poplars. Aitchison and others 2000 states 

that removal of 54 percent of dioxane in 

contaminated water was achieved within 9 days in 

hydroponic environments by using hybrid poplar 

cuttings. Most of the removal (about 36 percent) 

was attributed to phytovolatilization. New 

research is examining the possibility of 

bioaugmenting the phytoremediation process with 

the bacterium Amycolata sp. Strain CB 1190 to 

enhance in situ biodegradation in the rhizosphere 

(Kelley and others 2001). Other studies have 

shown that phytoremediation is a viable alternative 

for dioxane in groundwater, although the 

technology’s effectiveness may be limited to 

shallow groundwater where contamination is 

confined to a limited depth within the root zone of 

the trees (up to about 15 feet deep for hybrid 

poplars) (EPA 2001). Aboveground hydroponic 

treatment systems may also be suitable for 

removing dioxane from extracted groundwater for 

low-flow groundwater treatment regimens. 

Phytoremediation may also serve to provide longterm stabilization of dioxane-contaminated soil 

that would otherwise require excavation and 

stockpiling (GRAC 2003). 

Photocatalysis is another emerging process used to 

treat dioxane. As opposed to hydrogen peroxide 

and UV light, where high energy photons are used 

to cleave the peroxide molecule and generate 

hydroxyl radicals, photocatalysis with titanium 

dioxide (TiO2) uses the full spectrum of UV light 

to activate the TiO2 catalyst, thereby creating 

organic destruction pathways. Purifics ES Inc. 

uses this technology in its Photo-CAT product line 

(Powell 2006). 

Another company, Accelerated Remediation 

Technologies, LLC (ART), uses in-well 

technology combining in situ air stripping, air 

sparging, soil vapor extraction, enhanced 

bioremediation, and dynamic subsurface 

groundwater circulation to treat dioxane 

contamination. The in-well technology was able 

to reduce dioxane concentrations by up to 90 

percent within 3 months during a pilot study 

conducted in North Carolina by Delta 

Environmental, Inc. (Odah and others 2005). 

 2-10 
3.0 REFERENCES 

Agency for Toxic Substances and Disease 

Registry (ATSDR). 2004. “Toxicological 

Profile for 1,4-Dioxane. Draft for Public 

Comment.” Available online at 

http://www.atsdr.cdc.gov/toxprofiles/tp187. 

html. September. 

Aitchison, E.W., Sara L. Kelley, Pedro Alvarez, 

and Jerald L. Schnoor. 2000. 

“Phytoremediation of 1,4-Dioxane by Hybrid 

Poplar Trees.” Water Environmental 

Research. Volume 72, Number 3. Pages 313 

through 321. 

http://www.ingentaconnect.com/content/wef/ 

wer/2000/00000072/00000003/art00008;jsessi 

onid=dh4bhdlcak8jb.alice. 

Alvarez-Cohen, L. 2005. “Oxygenase-Catalyzed 

Biodegradation of Emerging Water 

Contaminants: 1,4-Dioxane and 

N-Nitrosodimethylamine.” In: Partners in 

Environmental Technology Technical 

Symposium & Workshop. Strategic 

Environmental Research and Development 

Program/Environmental Security Technology 

Certification Program (SERDP/ ESTCP). 

November 29-December 1. 

http://www.serdp.org/research/CU/CU_1417. 

pdf. 

Applied Process Technology, Inc. (APT). 2005a. 

City of Industry, CA: HiPOx Industrial Site 

Remediation.” HiPOx: The Best Solution for 

Removing 1,4-Dioxane From Groundwater, 

Rev. C. Page 7-3. 

APT, Inc. 2005b. “Pacific Northwest: HiPOx 

Industrial Site Remediation.” HiPOx: The 

Best Solution for Removing 1,4-Dioxane From 

Groundwater, Rev. C. Page 7-6. 

APT, Inc. 2005c. “Orange County, CA: HiPOx 

Industrial Site Remediation.” HiPOx: The 

Best Solution For Removing 1,4-Dioxane from 

Groundwater, Rev. C. Page 7-5. 

Berman, M., M. Darrow, C. DeMai, T. Gretarsson, 

P. Karakelian, T. Krantz, and R.Martel. 1998. 

“Remedial Design for the Cornell University 

Radioactive Waste Disposal Site, Ithaca, New 

York.” May. 

Boarer, J.E., and R. Milne. 2004. “1,4-Dioxane 

Treatment in Mountain View, California.” 

Pollution Engineering. July. 

http://www.aptwater.com/assets/news_articles 

/ArticlePE0704.pdf#search=%22dioxane%20treatmen 

t%20pollution%20engineering%22. 

Bowman, R.H., P. Miller, M. Purchase, and R. 

Schoellerman. 2003. “Ozone-Peroxide 

Advanced Oxidation Water Treatment System 

for Treatment of Chlorinated Solvents and 1,4­

Dioxane.” NGWA Conference on MTBE: 

Assessment, Remediation, and Public Policy. 

Baltimore, Maryland. June 6. 

Brode, J., F. Fotouhi, and S. Kolon. 2005. 

“Ultraviolet and Hydrogen Peroxide 

Treatment Removes 1,4-Dioxane from 

Multiple Aquifers.” Technology News and 

Trends. January. http://cluin.org/products/newsltrs/tnandt/view.cfm? 

issue=0105.cfm. 

Burgess, M. EPA. 2005. Comments on draft 

“Treatment Technologies for 1,4-Dioxane: 

Fundamentals and Field Applications.” 

CHEMFATE. 2003. Database Listing for 1,1,1­

Trichloroethane. 

http://www.syrres.com/esc/chemfate.htm. 

Federal Remediation Technologies Roundtable 

(FRTR). 2006. “Remediation Technologies 

Screening Matrix and Reference Guide.” 

Version 4.0. http://www.frtr.gov/matrix2/. 

Gronstal, D. McClellan AFB. 2006. Telephone 

conversation with Sankalpa Nagaraja, Tetra 

Tech EM Inc., regarding the dioxane treatment 

system at McClellan AFB. October 20. 

 3-1 
Groundwater Resources Association of California 

(GRAC). 2003. “1,4-Dioxane and Other 

Solvent Stabilizer Compounds in the 

Environment.” The Ninth Symposium in 

GRAC’s Series on Groundwater 

Contaminants. San Jose, California. 

December 10. 

http://www.grac.org/dioxanemain.html. 

Horst, J.F. ARCADIS. 2005. Comments on draft 

“Treatment Technologies for 1,4-Dioxane: 

Fundamentals and Field Applications.” 

International Agency for Research on Cancer 

(IARC). 1999. “Re-Evaluation of Some 

Organic Chemicals, Hydrazine and Hydrogen 

Peroxide.” Monographs on the Evaluation of 

Carcinogenic Risk of Chemicals to Man. 

Volume 71. Pages 589 through 602. 

http://monographs.iarc.fr/ENG/Monographs/ 

vol71/volume71.pdf. 

Joshi, S.B., B.A. Donahue, A.R. Tarrer, J.A. Guin, 

M.A. Rahman, and B.L. Brady. 1989. 

“Methods for Monitoring Solvent Condition 

and Maximizing Its Utilization – STP 1043.” 

The American Society for Testing and 

Materials (ASTM). Philadelphia, 

Pennsylvania. 1989. Page 80 through 103. 

Kelley, S.L., E.W. Aitchison, M. Deshpande, J.L. 

Schooner, and P.J. Alvarez. 2001. 

“Biodegradation of 1,4-Dioxane in Planted 

and Unplanted Soil: Effect of 

Bioaugmentation with Amycolata sp. CB 

1190.” Water Research. Volume 35, Number 

16. Pages 3791 through 3800. 

Lancaster Laboratories, Inc. 2003. “GC/MS 

Groups Aid Clients with 1,4-Dioxane 

Analyses.” Fall. 

http://www.lancasterlabs.com/whatsnew/ 

envpersp/fall2003/1-4dioxane.htm. 

Ludwig, R. 1997. “Pumping and Treatment of 

Groundwater at the Gloucester Landfill Site.” 

In: Site Remediation Technologies: A 

Reference Manual. Contaminated Sites 

Management Working Group. March. 

http://www.ec.gc.ca/etad/csmwg/pub/site_me 

m/en/xb_e.htm. 

Mohr, T.K.G. Santa Clara Valley Water District 

of California. 2001. “Solvent Stabilizers 

White Paper.” Prepublication Copy. San 

Jose, California. June 14. 

http://www.valleywater.org/water/Water_Qual 

ity/Protecting_your_water/_Solvents/_PDFs/ 

SolventStabilizers.pdf#search=%22Solvent%2 

0Stabilizers%20White%20Paper%22. 

Mohr, T.K.G. 2005. Comments on draft 

“Treatment Technologies for 1,4-Dioxane: 

Fundamentals and Field Applications.” 

Occupational Safety and Health Administration 

(OSHA). 1998. “Occupational Safety and 

Health Standards, Toxic and Hazardous 

Substances.” 29 Code of Federal Regulations 

1910.1000. 

Odah, M.M., R. Powell, and D.J. Riddle. June. 

2005. “ART in-well technology proves 

effective in treating 1,4-dioxane 

contamination.” Remediation Journal. 

Volume 15, Issue 3. Pages 51 through 64. 

Parales, R.E., J.E. Adamus, N. White, and H.D. 

May. 1994. “Degradation of 1,4-Dioxane by 

an Actinomycete in Pure Culture.” Applied 

and Environmental Microbiology. Volume 

60, Number 12. Pages 4527 through 4530. 

http://aem.asm.org/cgi/content/abstract/60/12/ 

4527. 

Powell, T. January 2006. Photo-Cat Case 

Histories & Technology Briefing. 

www.purifics.com. 

Steffan, R.J. 2005. “Biodegradation of 1,4­

Dioxane”. In: Partners in Environmental 

Technology Technical Symposium & 

Workshop. SERDP/ESTCP. November 29 ­

December 1. 

http://www.serdp.org/Symposium/index.cfm#l 

astyear. 

Suh, J.H. and M. Mohseni. 2004. “A Study on 

the Relationship Between Biodegradability 

Enhancement and Oxidation of 1,4-Dioxane 

Using Ozone and Hydrogen Peroxide.” Water 

Research. Volume 38. Pages 2596 through 

2604. 

 3-2 
Tetra Tech EM Inc. (Tetra Tech). 2003. 

Teleconference with Thomas K.G. Mohr, 

Santa Clara Valley Water District of 

California. July 2. 

U.S. Army Corps of Engineers (USACE). 2004. 

“Innovative Technology Success Stories: 

Charles George Landfill.” 

http://hq.environmental.usace.army.mil/tool_i 

nfo/it/itsuccess/charles2/charles2.html. 

USDHHS. 2002. “Report on Carcinogens.” 

Public Health Service, National Toxicology 

Program. Tenth Edition. December. 

http://ehp.niehs.nih.gov/roc/toc10.html. 

USDHHS. 2003. National Toxicology Program 

Web site. 

http://ntp.niehs.nih.gov/index.cfm?objectid=0 

703C9B2-9F3B-C96D-D7039F6B47F18098. 

U.S. Environmental Protection Agency (EPA). 

2000. “Method 8261. Volatile Organic 

Compounds by Vacuum Distillation in 

Combination with Gas Chromatography/Mass 

Spectroscopy (VD/GC/MS).” In SW-846 

Draft Update IVB. November. 

http://www.epa.gov/sw-846/pdfs/8261.pdf. 

EPA. 2001. “Brownfields Technology Primer: 

Selecting and Using Phytoremediation for Site 

Cleanup.” EPA 542-R-01-006. July. 

http://www.brownfieldstsc.org. 

EPA. 2003. Toxics Release Inventory Explorer. 

http://www.epa.gov/triexplorer. 

EPA Integrated Risk Information System (IRIS). 

2005. “1,4-Dioxane (CASRN 123-91-1).” 

http://www.epa.gov/IRIS/subst/0326.htm. 

Walsom, G and B. Tunnicliffe. 2002. “1,4­

Dioxane – A Little Known Compound.” 

Environmental Science and Engineering 

Magazine. May. 

http://www.esemag.com/0502/tca.html. 

Zabaneh, M. 2004. E-mail to Martha Otto, U.S. 

Environmental Protection Agency 

Headquarters, Regarding the Advanced 

Oxidation System to Treat 1,4-Dioxane at 

McClellan Air Force Base. November 15. 

Zenker, M.J., R. C. Borden, and M.A. Barlaz. 

2000. “Cometabolism of Poorly 

Biodegradable Ethers in Engineered 

Bioreactors”. In: Bioremediation and 

Phytoremediation of Chlorinated and 

Recalcitrant Compounds, pg. 421. 

Proceedings of the Second International 

Conference on Remediation of Chlorinated 

and Recalcitrant Compounds. Monterey, 

California. 

http://www.battelle.org/BookStore/BookTemp 

late.aspx?ISBN=1-57477-098-5. 

Zenker, M.J., R.C. Borden, and M.A. Barlaz. 

2003. “Occurrence and Treatment of 1,4­

Dioxane in Aqueous Environments.” 

Environmental Engineering Science. Volume 

20, Number 5. Pages 423 through 432. 

http://www.aptwater.com/assets/tech_papers/ 

Paper-Zenker.pdf. 

 3-3 
APPENDIX A 

INTERNET SOURCES FOR SUMMARY OF SELECTED U.S. ENVIRONMENTAL 

PROTECTION AGENCY AND STATE GUIDANCE FOR DIOXANE IN SOIL AND WATER 

EPA Region 

or State Internet Source 

Region 3 EPA Region 3 Risk-Based Concentration Table 

http://www.epa.gov/reg3hwmd/risk/human/rbc/rbc0406.pdf 

Region 6 EPA Region 6 Human Health Medium-Specific Screening Levels 

http://www.epa.gov/earth1r6/6pd/rcra_c/pd-n/screenvalues.pdf 

Region 9 EPA Region 9 PRG 

http://www.epa.gov/region09/waste/sfund/prg/files/02table.pdf 

Arizona Arizona Administrative Code, Title 18, Chapter 7 

http://www.azsos.gov/public_services/title_18/18-07.htm 

California California Health-Based Advisory Levels, Table A 

http://www.swrcb.ca.gov/rwqcb2/RBSL/SFRWQCB%20RBSLs%20Vol.1(December 

%202001).pdf 

Colorado Colorado Department of Public Health and Environment, Water Quality Control 

Commission Regulations 

http://www.cdphe.state.co.us/op/regs/waterregs/100241basicstandardsforgroundwater. 

pdf 

Delaware Remediation Standards Guidance Under the Delaware Hazardous Substance Cleanup 

Act 

http://www.dnrec.state.de.us/dnrec2000/Divisions/AWM/sirb/DOCS/PDFS/Misc/Rem 

Stnd.pdf 

Florida University of Florida 

http://fdep.ifas.ufl.edu/TTable2.pdf 

Iowa Standards for Soil, Iowa Land Recycling Program 

http://www.iowadnr.com/land/consites/lrp/conLRP.html 

Maine Maximum Exposure Guidelines for Drinking Water 

http://mainegov-images.informe.org/dhhs/eohp/wells/megtable.pdf 

Michigan Rule744Table.pdf, Rule748Table.pdf, and Rule746Table.pdf 

http://www.michigan.gov/deq/0,1607,7-135-3311-58095--,00.html 

Missouri Cleanup Levels for Missouri 

http://www.dnr.state.mo.us/alpd/hwp/pub468b.pdf 

Pennsylvania Effective Statewide Health Standard MSCs 

http://www.pacode.com/secure/data/025/chapter250/s250.708.html 

Texas Texas State Cleanup Levels, Search Engine 

http://www.pela.com/SCLs/TCLSearch.asp 

West 

Virginia 

West Virginia Voluntary Remediation and Redevelopment Act 

http://www.dep.state.wv.us/Docs/3200_RemediationGuidanceVersion2-1.pdf 

Wyoming Soil Cleanup Level Look-up Table Under the Voluntary Remediation Program 

http://deq.state.wy.us/volremedi/downloads/Fact%20Sheet%2012%20Jan05/F%20S% 

2012%2001-06-05%20clean.pdf 

 A-1