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Hazardous Waste

Guidance for Cleaning Up Groundwater, Soil and Air at Corrective Action Facilities

Accidents or other activities at Resource Conservation and Recovery Act (RCRA) facilities sometimes result in releases of hazardous waste or hazardous constituents into soil, groundwater, surface water, sediments, or air. The Corrective Action Program requires such facilities to conduct investigations and cleanup actions (remediation of the contamination) as necessary to protect human health and the environment. EPA developed guidance documents to assist regulators, members of the regulated community, and members of the public understand and implement Corrective Action cleanup of different types of media, including: groundwater, soil, and air (vapor intrusion) after a release has occurred.

Guidance documents do not impose legally binding requirements on EPA, States, or the regulated community, and may not apply to a particular situation based upon the specific circumstances of the Corrective Action facility. EPA’s legal authority to require facility-wide Corrective Action comes from RCRA.

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Guidance for Groundwater Cleanups

EPA’s corrective action goal for groundwater is to prevent adverse effects to human health and the environment, both now and in the future. EPA believes that short-term exposure prevention and long-term cleanup goals are both essential elements to achieve this overall goal. With respect to short-term exposure prevention, EPA works with Corrective Action facilities to interrupt current and prevent new exposure routes through groundwater. With respect to long-term cleanup goals, facilities and regulators generally focus first on cleanup activities that limit the exposure risk to humans. Then the focus shifts to cleaning up and restoring currently used and reasonably expected sources of drinking water as well as groundwater that is closely hydraulically connected to surface waters, whenever such restorations are practicable and attainable.

EPA developed groundwater guidance to help regulators, members of the regulated community, and members of the public better understand EPA’s groundwater cleanup cleanup approaches, technical protocols, and policies. Additionally, EPA recommends that facilities, regulators, and members of the public use these guidance documents to focus discussions and to ultimately improve the quality of groundwater at and near Corrective Action facilities.

Guidance Documents Pertaining to Groundwater

Name of Document Description of Document

Handbook of Ground Water Protection and Cleanup policies for RCRA Corrective Action

This handbook and the accompanying documents are designed to help regulators, members of the regulated community, or members of the public find and understand EPA policies on protecting and cleaning up groundwater at Resource Conservation and Recovery Act (RCRA) Corrective Action facilities. This handbook contains EPA’s interpretation of policies on such topics as cleanup goals, the role of groundwater use, point of compliance, source control, and monitored natural attenuation.

Technical Protocol for Evaluating Natural Attenuation of Chlorinated Solvents in Groundwater (PDF)(248 pp, 24.7 M, About PDF)

The intent of this document is to present a technical protocol for data collection and analysis to evaluate monitored natural attenuation through biological processes for remediating groundwater. Natural attenuation processes, such as bio-degradation, can often be dominant factors in the fate and transport of contaminants. Thus, consideration and quantification of natural attenuation is essential to a more thorough understanding of contaminant fate and transport.

Use of Monitored Natural Attenuation at Superfund, RCRA Corrective Action and Underground Storage Tank Sites (41 pp, 286 K, About PDF)

The purpose of this Directive is to clarify EPA’s policy regarding the use of monitored natural attenuation (MNA) for the cleanup of contaminated soil and groundwater in the Superfund, RCRA Corrective Action, and Underground Storage Tank programs.

Guidelines for Groundwater Classification Under the 1984 EPA Groundwater Protection Strategy, Final Draft (253 pp, 10.3 K, About PDF)

The purpose of this document is to further define the classes, concepts, and key terms related to the classification system outlined in the 1984 Groundwater Protection Strategy, and to describe the procedures and information needs for classifying groundwater.

Waste Management Area (WMA) and Supplemental Well (SPW) Guidance

This document gives an overview of the waste management area (WMA) and the supplemental well (SPW) provisions of the RCRA Subtitle C groundwater monitoring regulations of 1988. These provisions were intended to increase flexibility in the RCRA groundwater monitoring program, so that monitoring systems may be better tailored to site-specific conditions and designed to foster the early detection of contaminated releases.

Alternate Concentration Limit Guidance

This document provides guidance to RCRA facility permit applicants and writers concerning the establishment of site-specific Alternate Concentration Limits (ACLs). To obtain an ACL, a permit applicant must demonstrate that the hazardous constituents detected in the groundwater will not pose a substantial present or potential hazard to human health or the environment at the ACL levels.

Protecting the Nation's Groundwater: EPA's Strategy for the 1990's

This report states EPA policy, accompanied by implementation principles that reflect an aggressive approach to protecting the Nation's groundwater resources. The policy puts clear priority on preventing ground-water contamination, recognizes that groundwater is a uniquely local resource tor which States and local governments must assume primary responsibility, and strives to improve EPA's coordination of groundwater activities under all relevant statutes and programs.

RCRA Section 3020(b) Guidance:

These documents provide guidance on RCRA Section 3020(b). RCRA section 3020(a) bans hazardous waste disposal by underground injection into a formation which contains an underground source of drinking water (within one-quarter mile of the well), or above such a formation. However, RCRA section 3020(b) exempts from the ban re-injection of treated contaminated ground water withdrawn from an aquifer, if certain criteria are met.

Final Comprehensive State Groundwater Protection Program Guidance

These documents are intended to describe the Comprehensive State Groundwater Protection Programs (CSGWPPs). CSGWPPs are the focal point for a new partnership between EPA, the States, Native American Tribes, and local governments to achieve a more efficient, coherent, and comprehensive approach to protecting the nation’s groundwater resources. Protecting groundwater sources usually requires the combined efforts of many partners such as public water systems, communities, resource managers, and the public.

State Source Water Assessment and Protection Programs Guidance (112 pp, 6.9 MB, About PDF)

The purpose of this document is to provide guidance required by the Safe Drinking Water Act (SDWA) Amendments of 1996 for state Source Water Assessment Programs (SWAP) and for Source Water Petition (SWP) Programs. This document describes the elements of an EPA-approvable SWAP submittal as well as EPA’s recommendations for what may be included in an SWP Program.

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Guidance for Soil/Sediment Cleanups

EPA’s corrective action goal with respect to contaminated soil/sediment is to prevent adverse effects to human health and the environment by protecting the integrity of the nation’s soil/sediment resources. EPA believes that short-term exposure prevention and long-term cleanup goals are essential elements of a strategy designed to achieve this overall goal. With respect to short-term exposure prevention, EPA works with facilities to interrupt current and prevent new exposure via direct pathways (e.g., dermal exposures, incidental ingestion, and inhalation of soils/dusts) as well as indirect pathways (e.g., ingestion of food crops and fish production). EPA also works with facilities in the short-term to address soil/sediment exposure routes that may cause negative impacts to ecosystems. With respect to long-term cleanup goals, facilities and regulators generally focus first on cleanup activities to limit the risk to human health by limiting exposure. Then the focus shifts to cleaning up contaminated soils/sediments that are currently being used or reasonably expected to be used for residential or food production purposes or that are causing significant ecological impacts, whenever such restorations are practicable and attainable.

There are many methods of treating or cleaning-up contaminated soils/sediments including both in-situ (treating in the ground) and ex-situ (removal of soil to treat) remediation considerations. The main methods used include: containment, soil washing, thermal treatment, vapor extraction, bio-remediation, incineration, and other physical/chemical treatments.

Guidance Documents Pertaining to Soil/Sediment Cleanups

Name of Document Description of Document
Best Management Practices for Soil Treatment Technologies

This document provides guidance on how to design and conduct soil remediation activities at Resource Conservation and Recovery Act (RCRA) and other hazardous waste sites so that transfers of contaminants from contaminated soil to other media (i.e., clean soil, air, and surface or groundwater) are minimized. This document also gives advice on the prevention and control of contamination through Best Management Practices that, based on research and past experience, may be best for the selected technology.

Clarification to the 1994 Revised Interim Soil Lead Guidance for CERCLA Sites and RCRA Corrective Action Facilities
This directive clarifies the policy on using EPA’s Science Advisory Board reviewed Integrated Exposure Uptake Biokinetic Model and blood lead studies, determining the geographic area to use in evaluating human exposure to lead contamination, addressing multimedia lead contamination, and determining appropriate response actions at lead sites
Soil Treatment Standards (PDF) (17 pp, 82.4 K, About PDF)

This memo clarifies the effective dates for the major provisions of the Phase IV rule. Among other things the Phase IV rule promulgates treatment standards for contaminated soil subject to Land Disposal Restrictions (LDRs).

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Guidance for Air (Vapor Intrusion) Cleanups

Vapor intrusion is the general term given to the migration of hazardous vapors from any subsurface vapor source (i.e., contaminated soil or groundwater) into the indoor air of an overlying building or structure. These vapors can enter buildings through cracks in basements and foundations, as well as through conduits and other openings in the building envelope. All types of buildings, regardless of foundation type (e.g., basement, crawl space, slab-ongrade), have openings that render them potentially vulnerable to vapor intrusion.

When and where vapor intrusion occurs, concentrations of vapors can increase gradually in amount in buildings or structures as time passes (i.e., “accumulate”). Depending upon site- and building-specific circumstances, vapors of potentially toxic chemicals may accumulate to a point where the health of the occupants (e.g., residents, workers, etc.) in those buildings could be threatened. In addition to their toxicity threats, methane and certain other vapor-forming chemicals can pose explosion hazards depending upon structure-, building-, and site-specific circumstances. Explosion hazards may pose an imminent and substantial danger to human health and public welfare.

Response actions to address vapor intrusion when it poses unacceptable human health risks typically entail a combination of: remediation to reduce or eliminate subsurface vapor sources; engineered exposure (mitigation) controls for specific buildings to reduce vapor intrusion or reduce concentrations of vapor-forming chemicals that have already entered the building; monitoring to assess and verify the performance and effectiveness of the remediation systems and engineered exposure controls; and institutional controls (ICs) to restrict occupancy and land use and/or to alert parties (e.g., prospective developers, owners, and municipalities) of the presence of subsurface sources of vapor-forming chemicals and to foster operation, maintenance, and monitoring of the remediation systems and engineered exposure controls.

Guidance Documents Pertaining to Air (Vapor Intrusion) Cleanups

Name of Document Description of Document
Fact Sheet: Evaluating the Vapor Intrusion into Indoor Air

The following guidance document addresses the evaluation and management of a single exposure pathway – the vapor intrusion pathway. The intent of these guidance documents is to provide a tool to help the user conduct a screening evaluation as to whether or not the vapor intrusion exposure pathway is complete and, if so, whether it poses an unacceptable risk to human health. A complete pathway means that humans are exposed to vapors originating from site contamination. The documents provide limited recommendations for delineating extent of risk or eliminating risk.

Technical Guide for Assessing and Mitigating the Vapor Intrusion Pathway from Subsurface Vapor Sources to Indoor Air

This technical guidance presents EPA’s technical recommendations based on our current understanding of vapor intrusion into indoor air from subsurface vapor sources. One of its main purposes is to promote national consistency in assessing the vapor intrusion pathway. 

Background Indoor Air Concentration of Volatile Organic Compounds in North America Residences (1990-2005): A Compilation of Statistics for Assessing Vapor Intrusion

This technical report presents a summary of indoor air studies that measured background concentrations of Volatile Organic Compounds (VOCs) in the indoor air of thousands of North American residences and an evaluation and compilation of the statistical information reported in these studies. The objective of this compilation is to illustrate the ranges and variability of VOC concentrations in indoor air resulting from sources other than vapor intrusion.

Conceptual Model Scenarios for the Vapor Intrusion Pathway

This report provides simplified simulation examples to illustrate how subsurface conditions and building-specific characteristics determine the distribution of vapor-forming chemicals in the subsurface, and the indoor air concentration relative to a source concentration.  It was prepared to help environmental practitioners gain insights into the processes and variables involved in the vapor intrusion pathway and to provide a theoretical framework with which to draw inferences about and better understand the complex vapor fate and transport conditions typically encountered at actual, non-idealized contaminated sites.

Technical Guide for Addressing Petroleum Vapor Intrusion at Leaking Underground Storage Tank Sites

This guidance focuses on releases of petroleum-based fuels (e.g., gasoline, diesel) from underground storage tanks (USTs), which are typically located at gas stations. This guide applies to new and existing releases of petroleum-based fuels from leaking USTs and to previously closed sites, where the implementing agency has reason to suspect that there may be a potential for petroleum vapor intrusion.

EPA's Vapor Intrusion Database: Evaluation and Characterization of Attenuation Factors for Chlorinated Volatile Organic Compounds and Residential Buildings

This report presents technical information about sites in the U.S. that have been investigated for vapor intrusion. The primary focus of the report is the evaluation of concentrations of chlorinated Volatile Organic Compounds in and underneath residential buildings based upon EPA's vapor intrusion database as of 2010. The technical information provided in this report may be useful for regulators, responsible parties, and others assessing and managing vapor intrusion investigation programs.

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