CNMI Environmental Screening Levels (ESLs)

The Commonwealth of the Northern Mariana Islands, Division of Environmental Quality prepared a Evironmental Screening Levels (ESLs) document in 2005 (Saipan, sponsored by a grant to CNMI from the US Environmental Protection Agency Region 9). An ESL Surfer is included. The CNMI DEQ ESLs is modeled after the Hawai'i Department of Health EALs and the California Environmental Protection Agency ESLs.

The CNMI DEQ ESLs are based on entirely on USEPA toxicity factors and surface water standards. The ESLs also include summary screening levels specifically for commercial/industrial areas and for "deep" (>1 to 3m) soils. The ESLs are a handy tool to informally screen sites outside of the USA as well as areas in the US mainland where comprehensive, local guidance is not available. Screening levels for acute toxicity concerns will be added to the CNMI DEQ ESLs in the near future. These should help indentify and prioritize heavily contaminated sites that may pose very near-term risks to human health and the environment. Saipan/Commonwealth of the Northern Mariana Islands Division of Environmental Quality Environmental Screening Levels Screening For Environmental Concerns at Sites With Contaminated Soil and Groundwater (Interim Final - October 2005)

The document Screening For Environmental Concerns at Sites With Contaminated Soil and Groundwater (October 2005) is a technical report prepared by Commonwealth of the Mariana Islands, Division of Environmental Quality. The document is modeled after a similar technical report prepared by California EPA and the Hawai’i Department of Health Screening For Environmental Concerns at Sites With Contaminated Soil and Groundwater (May 2005, updated August 2006). Information provided in the CNMI document is not intended to establish policy or regulation. Volume 1 of the document presents lookup tables of conservative Environmental Screening Levels ("ESLs") for over 100 chemicals commonly found at sites with contaminated soil and groundwater. Volume 2 describes how the ESLs were developed and provides detailed tables and appendices in support of the summary lookup tables. Excel spreadsheets for use in Tier 2 direct-exposure and soil leaching assessments are also provided, as is a PowerPoint presentation on the development and use of the ESLs.

The ESL document is intended to help expedite the assessment of contaminated sites for potential human health and environmental concerns. As an alternative to preparing "site-specific" screening levels or attempting to quantifying risk in a more formal risk assessment, data collected at a site can be directly compared to the ESLs and the need for additional work evaluated. It is anticipated that this document will be especially beneficial for use at small- to medium-size sites, where the preparation of a more formal risk assessment may not be warranted or feasible due to time and cost constraints. The ESLs are considered to be conservative. ESLs based on human health and ecological concerns are well below levels that would cause immediate, acute health effects. Soil, groundwater and/or soil gas data collected at a site should be directly compared to the ESLs. Based on this comparison and a review of actual site conditions, potential environmental concerns can be quickly identified. Under most circumstances, and within the limitations described, the presence of a chemical in soil, soil gas or groundwater at concentrations below the corresponding ESL can further be assumed to not pose a significant long-term or “chronic” threat to human health and the environment. Additional evaluation will generally be necessary at sites where a chemical is present at concentrations above the corresponding ESL. Active remediation may or may not be required, however, depending on site-specific conditions and considerations. This evaluation is documented in an “Environmental Risk Assessment.”

An outline of the information that should be provided in the text of the risk assessment is provided in Volume 1. While not required at most sites, an Environmental Risk Assessment may also include a traditional, detailed “Human Health” risk assessment as one part of that document (usually as an appendix). This expedited approach to site investigation, assessment and cleanup has been shown to be especially effective at sites with limited or relatively straightforward types of contamination, where the preparation of a more formal risk assessment may not be warranted or feasible due to time and cost constraints.

A worksheet for calculation of Tier 2, direct-exposure action levels has also been prepared (download below). The worksheet cannot be used as a stand-alone tool for a Tier 2 environmental risk assessment. All other potential environmental concerns must be included in the assessment (i.e., soil leaching, vapor intrusion, ecotoxicity, gross contamination, etc.). Refer to Volume 1, Chapter 3 of the ESL document for more information. Preparation of a Tier 2 spreadsheet and guidance for soil leaching concerns is currently under way. The ESL document incorporates USEPA Region IX Preliminary Remediation Goals (“PRGs”) as one of up to five different types of action levels for evaluation of contaminants in soil. As discussed in the accompanying user’s manual, the PRGs are not intended to be used as “stand alone” criteria for evaluation of contaminated sites. The PRGs are only intended to address direct exposure of humans to contaminants in soil. Evaluation of additional concerns must be carried out separately. The ESL document offers one approach to accomplish this.

For further information, please contact:

UPDATES The CNMI ESL document will be revised and updated as needed. Updates will be posted to this website and notification sent to persons on the CNMI ESL mailing list as well as the Hawai’i DOH mailing list. To be included on the mailing list, send a note to RayMasga@deq.gov.mp or roger.brewer@doh.hawaii.gov.

2009 ESL Surfer

The following documents are available regarding this topic:

DEQ Environmental Screening Levels - ESL

DEQ ESL Lookup Tables