Department of Health Seal

TGM for the Implementation of the Hawai'i State Contingency Plan
Section 16.1


Remedial response actions are typically more complex than removal actions and often require additional site investigation to support appropriate decisions. The remedial investigation helps define and evaluate the nature and magnitude of the threat; but its primary goal is to collect data for use in analyzing remedial alternatives and selecting an appropriate alternative for the site.

16.1.1 Remedial Investigation Scoping

The first step in conducting a remedial investigation is investigation scoping. Existing information is assessed and analyzed, and data needs identified. It is not uncommon for additional site investigation to be required to support appropriate decisions in the remedial alternatives analysis.

The following steps should be conducted, as appropriate:

  • Assemble and evaluate existing site data
  • Identify and characterize the threat
  • Develop a conceptual site model to represent the site
  • Identify environmental hazards associated with contaminants that exceed State of Hawai`i Department of Health (HDOH) Tier 1 environmental action levels (EALs)
  • Identify applicable requirements and guidance to be considered
  • Identify data needed to support remedial alternative selection
  • Notify natural resources trustees if natural resources are or may be affected
  • Develop field sampling plan and quality assurance project plan
  • Prepare site-specific health and safety plan

As discussed in Section 3.1, project scoping is a critically important step for developing a successful investigation. Inadequate scoping can lead to failures such as:

  • Overlooking a significant contaminant
  • Overlooking a significant contaminant transport pathway
  • Overlooking a significant area of contamination
  • Overlooking a sensitive receptor
  • Collecting unusable data due to poor sample plan design
  • Not collecting the data needed for remedial alternatives analysis
  • Selecting an inappropriate cleanup method due to poorly collected data

16.1.2 Preliminary Identification of Likely and/or Presumptive Cleanup Alternatives

The identification and development of cleanup alternatives starts early and is dynamically revised as new data is collected. Based on the scoping phase and degree of site investigation data available, an initial set of potential remedial actions may be identified based on the type of contaminant, type of contaminated media, etc.

"Presumptive remedies" are available for several typical release scenarios (e.g., typical contaminants or disposal practices, or based on effects on environmental media). United States Environmental Protection Agency (USEPA) provides guidance on presumptive remedies, which are preferred by the HEER Office where appropriate. The USEPA Presumptive Remedies website.

When reviewing presumptive remedy guidance documents, confirm that cited methods are still considered to be best/good practices. Changes in cleanup technologies, scientific understanding, regulatory requirements, or public acceptance may affect whether a presumptive remedy is considered to be the preferred choice for a particular site.

The USEPA has developed specific presumptive remedy guidance documents pertaining to wood treatment sites, municipal landfills, volatile organic compounds (VOCs) in soils, and contaminated groundwater for Comprehensive Environmental Response, Compensation & Liability Act (CERCLA) sites. Other organizations such as the Interstate Technology and Regulatory Council (ITRC) also publish documents on the testing, performance, and feasibility of selected remediation technologies and can be good sources of information when selecting or considering remedy alternatives. The ITRC website can be found at:

A detailed discussion of common cleanup technologies is presented in Section 17.

16.1.3 Remedial Investigation and Remedial Investigation Report

The HEER Office will require submittal of a Remedial Investigation Report for sites following the remedial action process. The report compiles data collected from previous investigations (if relevant and representative of site conditions), plus supplemental investigation data collected to assist in characterizing the site and/or selecting remedial alternatives.

The Remedial Investigation should follow the guidance provided in Section 3 for site investigation design and implementation. The Remedial Investigation Report should be prepared according to the guidance provided in Section 18 on preparing Site Investigation Reports.