Department of Health Seal

TGM for the Implementation of the Hawai'i State Contingency Plan
Section 13.6


The Environmental Hazard Evaluation should serve as a "stand alone" report that provides a good summary of environmental impacts at a site and the existing or potential hazards posed by the contamination. A discussion of Environmental Hazard Evaluation reports is provided in the HDOH document Screening for Environmental Hazards at Site with Contaminated Soil and Groundwater (HDOH, 2016). A summary of the type of information that should be included in the report is provided below:

  1. Site background - summarize past, current and anticipated future site activities and uses:
    • Describe past and current site uses and activities.
    • Describe foreseeable future site uses and activities.
  2. Summary of investigations (including to-scale maps with a north arrow):
    • Identify all types of impacted media (soil, groundwater, surface water, etc.).
    • Identify all sources of chemical releases.
    • Identify initial chemicals of potential concern.
    • Identify magnitude and extent of impacts that exceed EALs to extent practicable and applicable (include maps of site with isoconcentration contours for soil and groundwater as practicable).
    • Identify nearby groundwater extraction wells, bodies of surface water and other potentially sensitive ecological habitats.
    • Ensure data are representative of site conditions.
  3. Applicability of HDOH EALs or alternative action levels:
    • Do Tier 1 EALs exist for all COPCs?
    • Does the site have a high public profile and warrant a fully documented, detailed human health risk assessment (in addition to an Environmental Hazard Evaluation)?
    • Do soil and groundwater conditions at the site differ significantly from those assumed in development of the lookup tables (e.g., low pH at mine sites)?
    • Do impacts pose a heightened threat to sensitive ecological habitats (e.g., presence of endangered or protected species)?
    • Have more than three carcinogens or five chemicals with similar noncarcinogenic health effects been identified?
  4. Selection of soil and groundwater categories:
    • State the regulatory beneficial use of impacted or potentially impacted groundwater beneath the site; discuss the actual, likely beneficial use of groundwater based on measured or assumed quality of the groundwater and the hydrogeologic nature of the soil or bedrock containing the groundwater.
    • Characterize the soil type(s) and location of impacted soil as applicable to the lookup tables (e.g., soil stratigraphy, soil texture and permeability, depth to and thickness of impacted soil, etc.).
  5. Selection of EALs & comparison to site data.
    • Summarize how Tier 1 EALs were selected with respect to the information provided above and additional assumptions as applicable.
    • Compare site data to the selected summary Tier 1 EALs and identify areas of soil or groundwater that pose potential environmental hazards.
  6. Identification of potential environmental hazards:
    • Identify specific environmental hazards associated with contaminants present above Tier 1 EALs (or acceptable, alternative action levels).
    • Prepare maps that summarize the extent and nature of potential environmental hazards (especially required for contamination to be managed in place over time).
  7. Conclusions and recommendations for follow up actions, possibly including:
    • Additional site characterization
    • Advanced evaluation of targeted environmental hazards
    • Preparation of a site-specific human health or ecological risk assessment
    • Evaluation of remedial alternatives
    • Preparation of an Environmental Hazard Management Plan
    • Need for land-use restrictions and/or institutional controls

The above is not intended to be exhaustive or representative of an exact outline required for all Environmental Hazard Evaluations. An EHE should be prepared for all sites. The level of detail required for an EHE will vary depending on the complexity of the site and the ease at which contamination concerns can be addressed. For sites that are fully remediated, the EHE could consist of a brief section in a final site investigation or remedial action report which simply states that no contamination above action levels remains at the site and that remaining contamination does not pose a significant threat to human health and the environment under any future site conditions. For relatively simple sites where contamination is still present, the EHE can be included as a separate chapter in the site investigation report with EAL Surfer printouts for target COPCs included in the report.

For more complicated sites where multiple site investigations have taken place over several years, a separate EHE report may be useful to summarize site data, identify specific environmental hazards posed by contamination and present recommendations for follow-up actions (e.g., additional investigation, remedial action plan, long-term management plan, etc.). As discussed above, maps that summarize the extent and magnitude of contamination as well as maps that depict areas of specific environmental hazards are very useful components of Environmental Hazard Evaluations (or some combined form of the maps). This information can be passed on to persons developing remediation action plans and/or EHMPs. Additional information regarding the required report formats and content are presented in detail in Section 18.

Conditions that pose immediate or short-term environmental concerns should be addressed as quickly as possible. This includes exposure of residents or workers to potentially harmful levels of contaminants in soil ("direct exposure"), impacts to water supply wells, intrusion of vapors or methane into overlying structures (including explosive hazards) and discharges of free product to surface water.

Note that the approach described above was referred to as Environmental Risk Assessment or Environmental Hazard Assessment in previous HEER Office guidance documents. The term "risk" has been replaced with the term "hazard" and the term "assessment" has been replaced with term "evaluation" in this guidance document. These changes were done to avoid confusion with traditional human health and ecological risk assessment and to emphasize the fact that some environmental concerns are not necessarily toxicological in nature, as the term "risk" is often interpreted to indicate. Examples include explosive hazards, leaching of contaminants from soil and even general gross contamination concerns. Human health and ecological risk are of course an important component of an Environmental Hazard Evaluation, but they cannot be used as stand-alone criteria to assess the need for potential cleanup actions at sites where contaminated soil and groundwater are identified.