Department of Health Seal

TGM for the Implementation of the Hawai'i State Contingency Plan
Section 13.0
ENVIRONMENTAL HAZARD EVALUATION

13.0 ENVIRONMENTAL HAZARD EVALUATION

This section provides an overview of the HDOH HEER Office approach to Environmental Hazard Evaluation, as described in the separate guidance document Screening for Environmental Hazards at Sites with Contaminated Soil and Groundwater (HDOH, 2016). Environmental Hazard Evaluation (EHE) is the link between site investigation activities and response actions carried out to address hazards posed by the presence of contaminated soil and groundwater, as shown in Figure 13-1.

Figure-13-1

Figure 13-1. Expanded Overview of the Environmental Hazard Evaluation Process. Note: COPC = Chemicals of Potential Concern.

In this step of the site assessment process, the presence or absence of potential environmental hazards associated with contaminated soil and groundwater is determined and summarized in an EHE (i.e., a review of potential environmental hazards), which must be carried out for all sites. As discussed below, the level of detail needed in an EHE will vary, depending on the extent and nature of contamination. This is most easily done at a screening level by comparison of site data to HDOH Tier 1 Environmental Action Levels (Tier 1 EALs). When the presence of a potential hazard(s) is confirmed, the specific hazard posed by the contamination is identified and the scope of follow-up actions necessary to address the hazard(s) is determined.

Once the site has been adequately characterized and potential environmental hazards identified, an appropriate response action is determined. If contamination is not identified above HDOH Tier 1 EALs then no further action is necessary. For sites where the extent of contamination that exceeds Tier 1 EALs is minimal or time is of the essence, the most cost-effective response may simply be disposal or treatment of the contaminated media. The Tier 1 EALs are not strict, regulatory cleanup standards, however. The practicability of full remediation in terms of access, anticipated land use, use of engineered and institutional controls, public acceptance, cost and other factors should be considered before final remedial actions are developed (refer also to Sections 14, Section 16, and Section 19 ).

A more detailed evaluation of specific environmental hazards is usually warranted at sites where contamination is identified above HDOH Tier 1 EALs. This could include the need for additional site data (e.g., soil gas data, bioaccessible arsenic data, etc.), the development of more site-specific cleanup levels, identification of the most pressing hazards (e.g., discharges of free product into storm sewers, vapor intrusion into overlying buildings) and other site-specific considerations. Contamination left in place following remediation of the site to the extent practicable and the specific environmental hazards posed by the contamination are documented in the final Site Investigation and Environmental Hazard Evaluation reports. This information is then used to prepare an Environmental Hazard Management Plan that describes actions for long-term management of the contamination (see Sections 18 and Section 19 ).

Environmental Hazard Evaluation is therefore an integral part of both site investigations and response actions. Site investigations and response actions carried out in the absence of a basic understanding of environmental hazards posed by contaminated soil or groundwater run the risk of being incomplete, and require unanticipated, additional field work. This can result in unnecessary delays and costs in addressing contamination issues and bringing the property back into productive use. The guidance presented in this document is intended to help avoid these types of problems and make the site assessment process as effective and efficient as possible.

A summary of the Environmental Hazard Evaluation process is presented within this section. A detailed description of Environmental Hazard Evaluations and associated Tier 1 Environmental Action Levels is presented in a separate guidance document entitled Screening for Environmental Hazards at Sites with Contaminated Soil and Groundwater (HDOH, 2016). Readers unfamiliar with the concept of environmental hazard evaluation may be familiar with the concepts of human health risk assessment and ecological risk assessment. As discussed below, human health and ecological risk assessment are two important components of the broader concept of environmental hazard evaluation. Traditional risk assessments may not adequately address all potential environmental concerns at a site, and cannot be used as a replacement for Environmental Hazard Evaluation. Note that in earlier HEER Office guidance this process was referred to as Environmental Hazard Assessment. The term assessment has been changed to evaluation in this guidance to help avoid confusion with traditional health and ecological risk assessment.

Additional information on the evaluation of environmental hazards associated with petroleum contamination (as well as other contaminants) is discussed in Section 9 and the primary EHE guidance (HDOH, 2016; see also HDOH, 2007).