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EPA Lowers Screening Levels for Lead in Residential Soil – March 24

The following article by Jeff Leed, M.S., of Montrose Environmental Solutions, Inc. (MES), was previously published as a blog on the MES website. We are very pleased to share Mr. Leed’s insights on this important topic in this issue of The Standard.

EPA Lowers Screening Levels for Lead in Residential Soil, Requiring Assessment of Large Numbers of Residential Sites and Re-Assessment of Previously Remediated Residential Sites

In a major news release recently issued in January 2024, the U.S. Environmental Protection Agency (EPA) announced that it has lowered its recommended screening levels for lead in residential soil. As a result of the new guidance for investigating and remediating lead-contaminated soil in residential areas, EPA will require cleanups of large numbers of new sites and will reevaluate the need for additional remediation of large numbers of residential properties where cleanups were previously performed.

Lead in the Environment

Lead is a naturally occurring metal that is ubiquitous in the environment, generally in low concentrations. Sources of lead contamination in the environment have historically included mining and milling sites, lead battery manufacturing and recycling facilities, primary smelters and secondary lead reclamation facilities, pesticide manufacturers, pesticide use in orchards, and paint manufacturers prior to 1978. Frequently, these facilities are located near residential areas or in areas where residential dwellings were constructed around them. Fugitive emissions from these sources, as well as residential sources of lead (such as lead-based paint on the inside and the exterior of older homes), can cause elevated lead levels in the soil in residential yards and can contribute to elevated blood lead levels in children. Lead is one of the most prevalent environmental contaminants addressed by various EPA and state regulatory programs.

History of EPA’s Screening and Cleanup Levels for Lead in Residential Soil

In 1989, EPA’s Office of Solid Waste and Emergency Response issued a directive that recommended a cleanup level of 500 to 1,000 parts per million (ppm) for lead in soil for protection of human health at residential sites. Although the directive was issued as guidance and specifically indicated that lead concentrations of 500 ppm to 1,000 ppm in residential soil were protective of human health, EPA frequently used the guidance to require cleanup of residential soil to 500 ppm lead and to require cleanup of soil on commercial and industrial properties to 1,000 ppm lead.

In 1994, EPA issued revised interim soil lead guidance for Superfund sites and for facilities subject to corrective action under the RCRA hazardous waste management program. The 1994 interim guidance recommended a screening level of 400 ppm for lead in the soil on residential properties. The 400 ppm lead screening level was based on the use of EPA’s Integrated Exposure Uptake Biokinetic (IEUBK) Model, which was developed by EPA to integrate exposure from lead in air, water, soil, dust, diet, and paint to predict blood lead levels in children (ages 6 months to 84 months, a particularly sensitive population).

Based on EPA’s 1989 and 1994 guidance and EPA’s regulatory programs which relied on the guidance, very large numbers of residential properties were remediated to meet EPA’s 500 ppm and 400 ppm lead-in-soil cleanup standards.

EPA Sets New Screening Levels for Lead in Residential Soil

For the first time in 30 years, and in an effort to strengthen its guidance for investigating and cleaning up lead-contaminated soil in residential areas where children live and play, EPA issued updated soil lead guidance on January 17, 2024 for Superfund and RCRA corrective action facilities that significantly lowers the screening levels for lead in residential soil. The new guidance indicates the following:

  • EPA lowered the screening level for lead in soil on residential properties from 400 ppm to 200 ppm; and
  • At residential properties with multiple sources of lead exposure (such as lead in air or water), EPA recommends a screening level of 100 ppm lead in residential soil.

In the guidance, EPA indicated that the new screening levels are not cleanup standards. Instead, the screening levels are intended to be used when initially investigating a site to determine whether the level of contamination is high enough to warrant further investigation.

For the purpose of its guidance, EPA defined a residential site with soil-lead contamination as “any areas where children have unrestricted access to lead-contaminated soil which include, but are not limited to, properties containing single- and multi-family dwellings, apartment complexes, vacant lots in residential areas, schools, day care centers, community centers, playgrounds, parks and other recreational areas, and green ways.

Significant Implications of EPA’s Actions

The guidance indicates that EPA regional staff should consider EPA’s new screening levels for all residential lead sites subject to Superfund response and RCRA corrective authorities, including:

  • New sites;
  • Previously remediated sites; and
  • Sites already deleted from the Superfund National Priorities List.

EPA expects that a significant number of residential properties will undergo evaluations as a result of EPA’s new guidance, EPA also expects that its regional offices will not be able to address all properties immediately. Until residential sites can be evaluated and cleanup can be completed, EPA recommends that early risk reduction strategies be implemented, which could include a combination of:

  • Engineering controls (e.g., barriers to prevent exposure risks);
  • Non-engineering actions (e.g., education and health intervention programs); and
  • Exposure reduction actions, such as institutional controls.

Developing Cleanup Levels for Lead-Contaminated Soil on Residential Properties

In its guidance, EPA recommends using the most current version of the IEUBK model to assess risk from exposure or potential exposure to soil lead contamination. EPA’s risk reduction goals for contaminated sites are to:

  • Limit the probability of a child’s blood lead concentration exceeding 5 µg/dL to 5% or less after cleanup. Under this scenario, and using the default parameters in the IEUBK model, the IEUBK model predicts a preliminary remedial goal of 200 ppm lead in residential soil.
  • Limit the probability of a child’s blood lead concentration exceeding 3.5 µg/dL to 5% or less after cleanup (for residential sites where an additional source of lead is identified, additional sources could include water service pipes made of lead, lead-based paint, or areas were lead-in-air concentrations exceed the NAAQS). Under this scenario, and using the default parameters in the IEUBK model, the IEUBK model predicts a preliminary remedial goal of 85 ppm lead in residential soil.

Considerations and Strategies

Montrose believes the impact of EPA’s new guidance will be significant. It will require EPA to assess large numbers of new residential sites and re-assess large numbers of previously remediated residential sites. Some of Montrose’s clients have called the new guidance a “game changer.”

For situations where EPA begins to assess new residential sites or previously remediated residential sites, qualified representatives of the potentially responsible business, industry, property owner and/or their consultants should consider active engagement with EPA to try to participate in, and shape the outcome of, EPA’s decision-making process. Some of the important factors to be considered as part of the property assessment process should include:

  • Can site-specific data be used, or be collected, to aid in decision-making?
  • Would it be helpful to collect site-specific data to recalibrate EPA’s model?
  • Is historical site-specific documentation available to define the extent of impacts or the extent of previous cleanups?
  • Can statistical methods (such as data averaging, etc.) be used to demonstrate attainment of EPA’s current levels?
  • Are EPA’s current levels being set for specific properties at levels that are below natural or anthropogenic background levels?
  • What are the actual exposure scenarios?
  • Was clean soil fill used to restore previously remediated areas?
  • Are engineering controls (such as paving barriers, etc.) in place to minimize exposure?
  • Are institutional controls (such as deed restrictions, environmental covenants, etc.) in place to restrict potential soil disturbance?
  • Can other site-specific factors be considered to minimize risk?

Montrose Environmental Group, Inc. and Montrose Environmental Solutions, Inc. have extensive experience in assessing, designing, and implementing effective remedial strategies for lead-impacted properties.

Also in this Issue: If you are curious about how quality assurance oversight can be beneficial on lead contamination projects, read Quality Assurance Applications for Non-Residential and Residential Lead Contamination Sites, by Lester Dupes, CEAC, of Environmental Standards. 

Jeff Leed, MS

Senior Scientist, Montrose Environmental Solutions, Inc.