EHE Guidance - Pacific Basin Edition

*Evaluation of Environmental Hazards at Sites with Contaminated Soil and Groundwater – Tropical Pacific Edition" is a technical report with accompanying electronic lookup tables and Environmental Screening Levels (ESLs) prepared for use in tropical areas outside of Hawaii, including Guam and the Commonwealth of the Mariana Islands. The title of the guidance was changed in 2016 from "Pacific Basin Edition" to "Tropical Pacific Edition" to emphasize the intended applicability of the included ESLs to tropical climate zones. The vapor intrusion screening levels, for example, assume warm, year-round temperatures and minimal to no heating of buildings. More conservative screening levels would be required for colder climates. Use of the guidance for environmental investigations should be discussed ahead of time with the overseeing regulatory agency. The most recent updates to the guidance are dated Summer 2016 (revisions made in November and December, 2016; refer to Updates worksheet in ESL Surfer). A summary of updates to the 2015 edition of the guidance is provided in the links below and in Volume 2, Appendix 8.

The Tropical Pacific edition of the EHE guidance follows similar guidance prepared by the Hawai‘i Department of Health (“Hawai‘i Edition”). A comparison of the two guidance documents is provided in Volume 1 of the document. The Hawai‘i guidance in particular makes default allowances for low-quality groundwater in pre-designated coastal zones, especially in highly developed and/or brackish, coastal areas of the islands. Drinking water standards are by law not applicable to these areas. Such default allowances may not be acceptable in other areas, however, where all groundwater is by default considered to be a potential source of drinking water that warrants a high degree of protection unless otherwise approved by the overseeing, regulatory agency (e.g., Guam).

The Tropical Pacific edition of the EHE guidance closely follows toxicity factors, water standards and other guidance published by the USEPA. Within the limitations noted in Volume 1 of the guidance, this helps make the Tropical Pacific edition of the EHE guidance more useful across a broad geographic area.

The guidance can be downloaded from the links provided below. Comments, suggestions and questions are welcome at any time and should be provided to the contact noted below.

Guam Environmental Protection Agency
Administration Building
17-3304 Mariner Avenue
Tiyan, Guam 96913
Telephone: 1-671-475-1658/59

Commonwealth of the Northern Mariana Islands
Ray Masga
Commonwealth of the Northern Mariana Islands
Division of Environmental Quality
Saipan, MP 96950-1304
Telephone: 1-670-664-8500

Attn: Roger C. Brewer
Office of Hazard Evaluation and Emergency Response
Hawai‘i State Department of Health
919 Ala Moana Boulevard, Room 206
Honolulu, Hawai‘i 96814

Tropical Pacific Environmental Hazard Evaluation (EHE) Guidance - Updated Summer 2016

The Tropical Pacific ("Pacific Basin") ESLs were updated and reposted in September 2016. The updates primarily reflect relatively minor adjustments to physiochemical constants used to develop the 2016 USEPA Regional Screening Levels. Actual changes to screening levels were minimal. Notes on certain individual topics were also expanded (e.g., applicability of vapor intrusion screening levels outside of tropical areas). The initial version of the Summer 2016 edition was updated in November 2016 to correct errors in the soil leaching model and make additional edits to the lookup tables and ESL Surfer. Refer to the Updates worksheet of the ESL Surfer for details.

Supplemental Models and Guidance

The Environmental Screening Level (ESL) Surfer is a searchable, electronic version of the ESL lookup tables. Use of the ESL Surfer to screen site data and expedite preparation of EHE reports is highly recommended. The Surfer automatically generates a summary page that can be included in reports. The Surfer also includes a glossary, a summary of information on the chemical selected and an overview of options for more advanced evaluations of environmental hazards. To use the ESL Surfer you must have Excel 2003 or newer installed on you computer. Simply download the Surfer from the link below then double click on the file to open the program. If you have trouble using the pulldown menus on the Surfer then remove the write protection (under the Tools menu). The password to unprotect the Surfer worksheets is “ESL.” The ESL Surfer is revised on a regular basis to reflect updates to the lookup tables in the ESL document. Please periodically check this webpage to ensure that you have the most up-to-date edition available.

Note – The write-protect password for all Excel file worksheets is ESL.


HDOH, 2016, "Evaluation of Environmental Hazards at Sites with Contaminated Soil and Groundwater" (Summer 2016 and updates): Hawai‘i Department of Health, Hazard Evaluation and Emergency Response.

USEPA, 2016, Screening Levels for Chemical Contaminants: U.S. Environmental Protection Agency, May 2016, prepared by Oak Ridge National Laboratories,