Site Assessment and Remediation


Tropical Pacific Environmental Screening Levels

Micro Beach, Saipan

*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.

REFERENCES: HDOH, 2017, Evaluation of Environmental Hazards at Sites with Contaminated Soil and Groundwater - Tropical Pacific Edition (Fall 2017): prepared by Hawai‘i Department of Health, Hazard Evaluation and Emergency Response.

Tropical Pacific Environmental Hazard Evaluation (EHE) Guidance - Updated Fall 2017

The Tropical Pacific EHE and ESL guidance was updated in October 2017. The updates primarily reflect relatively revisions to physiochemical constants used to develop the 2017 USEPA Regional Screening Levels and new information on TPH risk. Refer to Appendix 8 in Volume 2 and the Updates worksheet of the ESL Surfer for details. Revisions to action levels for common contaminants are not expected to significantly alter the results of past site investigations or site investigations currently underway.

The EHE guidance should be used in conjunction with HEER Office Technical Guidance Manual, which provides information on site investigation design and implementation as well as a an overview of the EHE process. Note that the ESLs refer to U.S. Environmental Protection Agency (USEPA) Regional Screening Levels (RSLs) as one of numerous sources for soil, water and air screening levels. As stated in the USEPA RSL guidance User’s Manual, The USEPA RSLs cannot be used as a stand-alone tool to evaluate the need for additional actions at contaminated sites. The USEPA RSLs only address direct exposure of humans to contaminants in soil. Other potential environmental hazards, including leaching and impacts to groundwater, vapor intrusion and gross contamination, have been incorporated into the ESLs to allow for a more comprehensive review of contaminated properties without the need to assess these issues separately.

The EHE guidance and associated supplemental material can be downloaded from the below links. Try using another browser if you have problems downloading files with the browser you are currently using. The ESL Surfer file has an “Updates” page with a summary of updates. Comments and suggestions from the general public are welcome at any time. Updates will be posted to this website and notification sent to persons on the EAL/ESL mailing list. Workshops to present and discuss the ESLs will also be held periodically. Contact Roger Brewer with the Hawaii Dept of Health HEER Office to provide comments or be included on the mailing list for updates and workshop announcements (

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. (HDOH, 2017)

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

For further information, please contact:

Commonwealth of the Northern Mariana Islands
Ray Masga
Bureau of Environmental & Coastal Quality
Division of Environmental Quality
P.O. Box 501304 C.K.
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


HDOH, 2017, Evaluation of Environmental Hazards at Sites with Contaminated Soil and Groundwater - Tropical Pacific Edition (Fall 2017): prepared by 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,


Last Updated 8/10/2017 3:50:58 PM