Triad is a Federal/State Interagency Partnership
Framing the Problem
The systematic planning foundation is formed by identifying stakeholders, articulating objectives, addressing constraints, recognizing the regulatory framework, and specifying decision statements.
The initial step in the systematic planning process is to identify stakeholders who should be involved in the planning process. These can include interested members of the local community, local governmental authorities, potentially responsible parties, upper management from the agency or entity responsible for cleanup, and state and/or federal regulatory authorities. From this stakeholder group, a Triad project planning team is formed, with the addition of a project manager and supporting technical staff as needed. The section entitled Triad Requirements provides additional discussion on stakeholder involvement. The critical characteristics of successful Triad planning teams are: 1) team members are committed to working through project challenges in a non-adversarial manner; 2) team members are available on an as-needed basis to support decision-making; 3) team members can speak confidently for their respective agencies or organizations; and 4) for projects with a long life cycle, there will be continuity of team member involvement to the degree possible.
The project planning team must agree on the overall objectives of the project to ensure that primary and secondary decisions can be identified and made with an acceptable level of confidence. In many cases, specific project objectives will change over time as project work progresses. For example, initially the goal may simply be to determine whether a site potentially poses a concern, or can be released from consideration. Later it may be to select and design a remedial action for a site with proven contamination concerns, or determine the nature of waste streams to support proper disposition. At the end of the project, it will be to achieve site closure.
Constraints and the Regulatory Framework
The planning team will also need to identify pertinent constraints and applicable, or relevant and appropriate requirements (ARARs). Examples of the former include funding constraints, schedule deadlines, or political realities. Examples of the latter include local, state, and/or federal regulations that will need to be considered through the life of the project. One of the key ARARs are action levels that must be achieved for specific contaminants. Depending on the situation, however, different action levels may be applicable for the same constituent in the same media. For example, action levels can be based on different types of exposure scenarios such as residential or nonresidential. Action levels for surficial soils are often different from those derived for deeper soils, and action levels based on human exposure are different from those for ecological receptors.
The regulatory framework is also important since there may be actions or sequences of actions predetermined by regulations. One of the Triad benefits is the possibility for streamlining and condensing the characterization, remediation, and site closure life-cycle. The extent to which this can be done partly depends on the rigidity of the applicable regulatory framework. As an example, a site covered by the NCP and included formally in the Superfund program will require a formal public review and comment process at key decision points such as issuance of the Record of Decision. Voluntary cleanup programs, on the other hand, often provide greater flexibility in the structure and implementation of characterization and remediation work.
After project objectives have been defined and pertinent constraints and ARARs identified and understood, the planning team needs to capture project objectives in the form of decision statements. The nature of decision statements will depend on where a site is in the cleanup process. Statements may be qualitative or quantitative, but should lay the foundation for the planning team to focus resources and define the boundaries of activities that will be necessary to reach a defensible decision. Primary decision statements will likely lead to more detailed, secondary decisions that are used collectively to make the primary decision.
A complete definition of the primary decision is essential. The complete definition should include the areas or population for which the decision must be made (note that this may have a temporal component as well). An example population would be all drums stored at a Brownfields site. A second example would be all groundwater from a potable aquifer underlying or down gradient from a suspect site. A third example would be all sediments to a depth of two feet found in an estuary. A final example would be all soils to a depth of six inches within a site boundary. A site may have several distinct populations to which the primary decision will apply (e.g., surface versus subsurface soils). The primary decision may be different for each of those distinct populations. The definition of populations will likely change and become more refined and specific over time as work at a site progresses and the CSM matures.
A complete definition should also define decision units. The decision unit identifies the spatial and temporal characteristics that define the decision's domain. Populations are broken into one or more discrete decision units. For example, a decision unit may be comprised of one or more drums containing waste materials. In the case of soils or sediments, it may be areas of a particular size down to a particular depth (e.g., 100 m2 to a depth of 15 cm). In the case of groundwater, the term point of compliance is synonymous with the decision unit. Example points of compliance for groundwater systems are monitoring wells located on a property boundary, screened over a specified depth. Alternatively, the point of compliance may be the location within the groundwater aquifer that is likely to have the highest concentration averaged over a particular screened interval. During the CERCLA remedial investigation process, the definition of exposure units is another example of a decision unit. During remediation planning and implementation, it may be advantageous to define remediation units (i.e., the fundamental area or volume to which remediation decisions will be applied), another example of a decision unit. Finally, during closure activities survey units may be defined with specific closure criteria applied to individual survey units.
An example of a primary decision that is common throughout the characterization and remediation process is the question about whether contamination for particular areas is present at levels that pose unacceptable human or ecological risks. The answer to this question early in the CERCLA process determines whether a remedial investigation is required after a site assessment. The answer during a remedial investigation determines whether a remedial action is warranted. The answer after a remedial action determines whether site cleanup objectives have been achieved.
Project managers need to be aware of a common, fundamental problem with cleanup definitions as part of decision statements. The problem arises when a cleanup requirement is established without specifying the area or volume over which it must be applied. Every cleanup requirement represents an average, whether the associated averaging area/volume is articulated or not. Even for cleanup criteria that are expressed as "never-to-exceed" values, the implicit assumption is that these are represented by homogenized (i.e., physically averaged) samples of some standard size from the media of concern. A cleanup requirement that does not explicitly specify the associated averaging area or volume will lead to an incomplete decision statement. This can produce significant confusion in the decision-making process, and will make it impossible to develop technically defensible data collection programs.
"Never-to-exceed" standards that are not accompanied by an area/volume definition are particularly problematic for two reasons. First, the range of analytical results observed in a set of samples (and consequently the maximum value one might encounter) is, in general, an inverse function of sample support size. The smaller the sample support, the larger the observed range. One can consequently have the situation where conflicting conclusions would be drawn dependent strictly on the size of the sample support used. As a simple example, with direct push technologies it is now possible to obtain "grab" samples of groundwater at specific depths. The interpretation of analytical results from such samples is different than that for a sample from the same vicinity drawn from a monitoring well screened over a significant depth. For a particular area, the results from ten traditional monitoring wells may all show compliance with a "never-to-exceed" guideline, while the results from ten adjacent subsurface grab samples could yield individual results significantly greater than the "never-to-exceed" value. Both could accurately reflect the reality represented by their sample supports.
The second reason is that it is usually not possible to develop a sampling program that demonstrates with some pre-specified level of confidence that a "never-to-exceed" standard has in fact been met for the entirety of a site. As a simple example, suppose there was a height restriction imposed on the residents of Chicago and the only means for establishing compliance was to "sample" or measure individuals. While relatively few random samples would establish whether the average height of Chicagoans was in compliance with the standard, short of measuring almost all, a similar statement could not be made about the possibility of one Chicagoan being too tall.
There are fundamentally two types of completely-defined cleanup requirements. The first is a wide-area or volume-averaged requirement. The averaging area may range from 100 m2 to an acre or more in size, and usually has some definition of depth of media as well (e.g., the top six inches of soil). The second is an elevated area (or "hot spot") criteria that represents a value higher than the wide-area averaged requirement, but that is applied as an average to a much smaller area. Sites can have a mix of these two types of requirements. Requirements such as these can be established by a regulatory authority, or they can represent site-specific risk or dose-based goals, with corresponding mass or activity concentration requirements derived using a site-specific risk or dose assessment model. Data collection strategies for addressing these two types of criteria will be discussed in the section entitled Dynamic Work Strategies. In general, wide-area or volume averaged requirements are addressed through statistically-based sampling that estimate the mean or median concentration value for the population captured by the averaging area. Elevated area criteria are typically addressed through judgmental, probabilistic, or search-based sampling strategies.
The area or volume associated with wide-area averaged cleanup requirements is usually equivalent to the definition of a decision unit. The area or volume associated with hot spot or elevated area requirements is typically significantly smaller than the size of a decision unit. Early on in the site characterization process, screening guidelines are sometimes used for specific contaminants of concern to quickly identify areas that may potentially present unacceptable human or ecological risks. Such guidelines rarely specify areas or volumes over which the guideline must apply, and in fact are usually interpreted as applying to homogeneous samples of some standard size for the media of concern. Even in this case the application of screening guidelines will benefit from a clear definition of the decision unit to which they will be applied.
In order to assure the reliability of project decision logic and project cost estimates in the systematic planning process, project managers are encouraged to seek assistance from technical experts as early as possible in a project's life cycle. Without appropriate training and experience it is less than obvious what constraints will control the success or failure for a project. The section entitled Triad Requirements discusses the technical staffing needs of a Triad-based approach in more detail.