1,4-Dioxane State Groundwater Regulations

Bryan Cave Leighton Paisner
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Summary

There is no federal drinking water standard for 1,4-dioxane, but as illustrated by a recent press release for the Industrial Excess Landfill Superfund Site in Ohio, the U.S. Environmental Protection Agency (EPA) and state environmental agencies have begun directing potentially responsible parties to conduct investigations to address the presence of 1,4-dioxane in drinking water and groundwater.  Some of these investigations are conducted at previously closed sites at which the chemical had not been initially identified as a contaminant of concern.  To protect the environment and avoid liability, any business in industries that use or produce this chemical must determine whether it needs to modify its operations to reduce or eliminate 1,4-dioxane.

This client alert surveys the remediation, guidance, and notification requirements for 1,4-dioxane in groundwater across the United States.

I. State Regulations and Guidance

The regulatory landscape for groundwater consists of an array of widely-varying state-promulgated standards and regulations.  For example, the lowest allowable concentration is 0.3 µg/L (Massachusetts and Vermont), and the highest value is 200 µg/L (Iowa). 

The map and chart are current as of August 29, 2022

Some states, such as California, have established an advisory Groundwater Information Sheet for 1,4-dioxane.  Other states, such as Connecticut, provided an advisory Technical Support Document for 1,4-dioxane (See Table 5).  Additionally, some states, such as Missouri, have listed 1,4-dioxane in the Risk-Based Corrective Action Program (MRBCA).

State

Concentration Level

Type of Regulation

Adoption Status

Colorado

0.35 µg/L

Advisory

The Basic Standards for Groundwater Regulation

Delaware

0.46 µg/L

Advisory

Hazardous Substance Cleanup Act Screening Level Table Guidance

Florida

3.2 µg/L

Advisory

Groundwater and Surface Water Cleanup Target Levels and Florida Department of Health: 1,4-Dioxane Information

Hawaii

0.46 µg/L

Advisory

Environmental Action Levels (See Table D-1a)

Kentucky

0.67 µg/L

Notification

KRS 224.1-530 and EPA Regional Screening Levels

Massachusetts

0.3 µg/L

Advisory

Massachusetts Contingency Plan (See pg. 197) and the Massachusetts Department of Environmental Protection’s 1,4-dioxane Fact Sheet

Montana

3 µg/L

Clean Up

Montana Numeric Water Quality Standards

Nebraska

0.46 µg/L

Advisory

Voluntary Cleanup Program Guidance Document

Note:  This requirement is only for the Voluntary Cleanup Program

New Hampshire

0.32 µg/L

Clean Up

New Hampshire Code of Administrative Rules Ch. Env-Or-600 and New Hampshire Department of Environmental Services 1,4-Dioxane Health Information Summary

New Jersey

0.4 µg/L

Notification

Ground Water Quality Standards and the New Jersey Department of Environmental Protection’s 1,4-dioxane Frequently Asked Questions

New York

1 µg/L (stated as 0.0010 mg/L)

MCL

Regulation and New York Department of Health Information

Note:  New York has proposed 0.35 µg/L for the GA class groundwater effluent standard

North Carolina

3 µg/L

Clean Up

Groundwater Quality Standards and the North Carolina  Environmental Quality’s Groundwater Information

Oregon

0.46 µg/L

Advisory

Risk-Based Concentrations for Individual Chemicals and Risk-Based Decision Making for the Remediation of Contaminated Sites Guidance

Vermont

0.3 µg/L

Guidance

Groundwater Protection Rule and Strategy

West Virginia

0.46 µg/L

Advisory

Voluntary Remediation and Redevelopment Rule

Note:  This requirement is only for the Voluntary Cleanup Program

Wisconsin

3 µg/L

Clean Up

Groundwater Quality Regulations and the Wisconsin Department of Health Services 1,4-Dioxane Information

Note:  Wisconsin also has a “preventive action limit” of 0.3 µg/L

Alaska

4.6 µg/L

Clean Up

Administrative Code

Georgia

4.6 µg/L (stated as 0.0046 mg/L)

Notification

Hazardous Site Response Regulation

Indiana

4.6 µg/L

Advisory

2022 Screening Levels

Maine

4.6 µg/L

Advisory

Maine Department of Environmental Protection Remedial Action Guidelines (See pg. 58)

Illinois

7.7 µg/L (stated as 0.0077 mg/L)

Notification

Groundwater Quality Regulation

Iowa

200 µg/L (stated as 0.2 mg/L)

Advisory

Statewide Standards

Kansas

8.49 µg/L (stated as 0.00849 mg/L)

Advisory

Risk-Based Standards (See App. A)

Michigan

7.2 µg/L

Clean Up

Michigan Department of Environmental Quality Environmental Contamination Response Activity

Mississippi

6.09 µg/L

Advisory

Risk Evaluation Procedures for Voluntary Cleanup and Redevelopment of Brownfield Sites

Note:  This requirement is only for the Voluntary Cleanup Program

Pennsylvania

6.4 µg/L

Notification

Regulation and Appendix

Note:  This requirement is only for the Voluntary Cleanup Program

Texas

9.1 µg/L (stated as 0.0091 mg/L)

Clean Up

Risk Reduction Rule (See Table 3 of the March 2022 PCL Table)

Washington

7.0 µg/L

Clean Up

Regulation

States with No 1,4-dioxane Groundwater Regulations or Enforceable Guidance (as of the date of publication):

Alabama, Arizona, Arkansas, California, Connecticut, Idaho, Louisiana, Maryland, Minnesota, Missouri, New Mexico, North Dakota, Ohio, Oklahoma, Rhode Island, South Carolina, South Dakota, Tennessee, Utah, Virginia, and Wyoming

Key:

Notification

A corporate representative may have to inform an appropriate state official that a groundwater source contributing to a public drinking water supply is above the limit. 

Advisory

The state establishes recommended concentration limits for 1,4-dioxane, but no notification or other action is required if concentrations exceed the recommended limits.

Clean Up

Investigation and remediation is usually required when concentration levels exceed the requirement.  Clean up standards are usually expressed by values that identify specific clean up criteria.

MCL

MCLs establish the maximum amount of 1,4-dioxane that can be present in water concentrations.  Treatment facilities that supply drinking water (by using groundwater supplies) must ensure that these limits are met by treating and filtering the water, and also by limiting the discharge of 1,4-dioxane through permits.

II. Conclusion

The regulation of 1,4-dioxane in groundwater will continue over the next several years as additional research is conducted on potential health impacts, and as regulators at both the federal and state levels develop a deeper understanding of the prevalence of 1,4-dioxane in groundwater. 

[View source.]

DISCLAIMER: Because of the generality of this update, the information provided herein may not be applicable in all situations and should not be acted upon without specific legal advice based on particular situations.

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