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Primary steps in CERCLA response activities and their relationship to the Triad.

CERCLA, as amended by SARA, was enacted to identify and remediate sites where hazardous substances were, or could be, released into the environment. CERCLA's mission to address uncontrolled releases of hazardous substances at non-operating facilities contrasts with RCRA's focus on operating facilities. The CERCLA legislation also differs from RCRA in that CERCLA specifies joint and several liabilities for all potentially responsible parties (PRPs). This means that any one individual, corporation, nonprofit group, or government agency that owned the site at the time of the release or any time thereafter, or any generator that contributed materials to the site or any transporter of hazardous substances to the site can be held liable for at least part of the cost of remediation.

CERCLA response activities are codified at 40 CFR Part 300 of the National Oil and Hazardous Substances Pollution Contingency Plan (NCP). Four primary steps are established by the NCP to respond to releases of hazardous substances under CERCLA. They are:

  • Site Discovery (SD). Site discovery occurs through various means, including reports of releases to EPA, investigations by government authorities, land inventories, or incidental discoveries. The result is that a site is reported to the National Response Center.

  • Site Assessment (SA). Site assessment includes conducting a preliminary assessment of available information about the site, and potentially a site inspection, if the preliminary assessment indicates the potential for concern. Among other things, a site inspection can include a minimal amount of sampling, typically judgmental in nature. The primary decision point is a determination of whether there is the potential for contamination at levels that would pose human health or ecological concerns, and if so, if the Hazard Ranking Score qualifies the site for placement on the National Priority List (NPL). Secondary decisions include determining if the site requires emergency, time-critical, or non-time critical removal actions to mitigate immediate threats to human health and the environment. From a Triad perspective, this begins the process of building the conceptual site model (CSM) for the site.

  • Remedial Investigation/Feasibility Studies (RI/FS). Data collection is the core activity for the remedial investigation/feasibility study phase of CERCLA. The preliminary CSM is further refined and matured with the intent that it will be accurate enough to support decisions about site risks and remediation. Information generated by data collection programs is used to characterize site conditions, determine nature and extent of contamination, evaluate risks posed by the site, and assess remediation options. Treatability studies may be included in this phase. The primary decision point is a determination of whether a site requires remediation, and if so, what remedial alternative is most attractive. The outcome is a Record of Decision (ROD) for the site. Included in the ROD are the cleanup standards that must be attained to be protective of human health and the environment.

  • Remedial Design/Remedial Action (RD/RA). During the remedial design/remedial action phase of CERCLA, the selected remedy is designed and implemented. Further refinement of the CSM is geared toward understanding contaminant distributions and the physical site conditions that affect remedial design. This may include the collection of additional remedy-specific site information required for proper design, and/or the collection of data during the course of remediation to verify and/or improve system performance. For remedial activities that have a long duration (e.g., enhanced bioremediation of contaminated groundwater, vapor extraction systems, etc.), the remedial action may include an operations and maintenance component. For sites that have on-going remedial activities and/or have not been remediated to unrestricted reuse release standards, at minimum a five year CERCLA review is required. The primary decision point is a determination of whether the site, or portions of the site, has attained cleanup standards as specified in the ROD. Secondary decision points include determining whether the remedial activity is performing as expected, and if not, what actions should be taken to improve performance.

The Triad approach has the possibility for playing a significant role in each of these steps. For the purposes of following sections, however, the focus will be on applicability to the last three, which is where the bulk of data collection activities take place. Compression of the Superfund process into a more seamless work flow has been successful for some Superfund projects (such as the Southern Shipbuilding site in Louisiana or under the auspices of the SACM (Superfund Accelerated Cleanup Model) program [see and]. The Triad can play an important role in facilitating these types of compressed approaches to cleanup.

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