A direct-push track rig enables S2C2 to access difficult terrain and to reduce sampling time and client cost.

The EPA's Triad approach incorporates three key components: systematic planning, real-time measurements and dynamic work strategies. The primary goal of this approach is to streamline site characterization, provide more accurate conceptual models of contaminant distribution to permit more accurate and effective remedy selection. Successful implementation of Triad and other streamlined site characterization methodologies should consider the following:

• Contaminated sites are viewed as heterogeneous.
• The Conceptual Site Model (CSM) provides the foundation for decision-making and systematic planning. It identifies project decisions and end points, structures an interactive project life cycle and clearly articulates project decision statements.
• Real-time measurements are utilized and include: field screening, geophysical techniques, direct-sensing technologies, on-site analytical methods and/or rapid turnaround of conventional analytical methods that can be used in conjunction with each other to provide collaborative data sets.
• Accurate CSMs are the basis for real-time, on-site decisions, and they require continuous adaptation as more information is obtained in the field.
• Dynamic work strategies, typically utilizing adaptive sampling procedures, allow for real-time decisions based on data generated in the field. These strategies require a focused approach employing logic and clearly articulated decision rules to continuously update the CSM.
• Field communications and data management strategies are necessary to efficiently organize, display and present large, complex data sets.

Hard-to-access terrain and geographically diverse locations require strong tools to plan activities, collect data, establish acceptable quality controls, and improve data analysis and presentation, and include, but are not limited to, the following:

• Direct-push sampling platforms – Includes both track- and truck-mounted rigs with auger capabilities, for rapid and precise environmental (e.g. soil, groundwater, soil vapor) sample collection.
• Direct-sensing technologies:
  • Fuel fluorescent detectors, or FFDs, often combined with cone penetrometer technology, or CPT, to detect aromatic hydrocarbons, and simultaneously generate a readout of the lithology. Continuous, real-time data readouts allow rapid delineation of LNAPLs in the subsurface.
  • Membrane interface probes, or MIPs, simultaneously define lithology and total VOCs.
  • Conductivity probes provide accurate and detailed lithologic information in a cost-effective manner.
  • On-site analytical capabilities provide onsite analysis of compound-specific contaminant suites including: VOCs, SVOCs, PCBs, pesticides, TPH or metals.
• Database management and data visualization.
• Field personnel experienced with technologies, equipment and a planned approach (e.g. Triad) to assist with the successful implementation of a streamlined site characterization program.

Data management

Plan view map of FFD sampling locations and modeled FFD response.

Managing and visualizing the large data sets that are typically associated with Triad programs requires well-organized data combined with a powerful retrieval system. S2C2 Inc., Raritan, N.J., uses EQuIS, from Earthsoft of Concord, Mass., as the backbone of its data processing engine for management and visualization of data sets, as well as for developing and continuously updating CSMs. These CSMs are delivered to stakeholders in ArcGIS, a geographical information system (GIS) by ESRI of Redlands, Calif.

All types of field data, e.g. direct-sensing data, GPS data, analytical laboratory data, are directly exported in electronic data deliverables (EDDs) and uploaded into the program, where the data can be delivered to third-party software packages.

Field borehole data from direct-sensing probes such as membrane interface probes, fuel fluorescent detectors and conductivity probes, as well as standard soil logs, are produced as S2C2-formatted logs. The logs are distributed to clients and field personnel though Web-based project portals, serving as a vehicle for the project team to communicate and implement field decisions in a timely manner.

Checking and exporting

A three-dimensional view of a fence diagram of FFD response, down-hole FFD profiles and interpreted geologic surfaces.

While on-site analytical data generated in a mobile laboratory is the source of real-time measurements, samples are delivered to the on-site laboratory, prioritized, extracted and analyzed. Preliminary results in the form of summary sheets (Form 1s, summary tables, etc.) are often available within hours of sample receipt, depending on the analysis required and sample matrix. Once on-site chemists check data quality, final laboratory data are exported to compatible EDDs, typically within 24 hours. These EDDs are then provided to the data management/data visualization personnel for loading and processing.

Electronic data checking allows for processing and validation of EDDs using project-specific reference values. Data errors can be corrected prior to processing using color-coded fields and a direct-data interface. Once data is loaded, the program can export reports, charts and data formatted for input into third-party software packages.

Modeling these complex data sets is initiated once a sufficient amount of information is collected to create a meaningful image. This model can then be used to identify additional data collection needs, analyze data relationships, or present findings to stakeholders. Real-time measurements (direct-sensing or on-site analytical results) are exported, and data modeling is conducted.

The receiver of these data is RockWorks, the flagship software of Golden, Colo.-based Rockware Inc. The program, in turn, allows for the generation and export of 3-D models of real-time measurement data to ArcGIS. Cross-sections, fence diagrams, and lithologic models also can be generated and exported.

Real-time measurement data allows constant updating of the initial CSM. As a result, additional data needs can be identified until end-point objectives are satisfied. End-point objectives, which have clearly been defined during systematic planning stages, can be best achieved with the constant input and judgment of experienced field team leaders, with further analysis provided by statistical software packages to manage data uncertainty, or a combination of the two.

Collaborating data sets

Three-dimensional model of MIP response with interpreted geology.

Because the Triad approach relies on a higher density of screening-level data to develop the CSM, collaborative data sets become an integral part of reducing data uncertainty which allows for more accurate decision making. Examples of collaborative data include:

• Obtaining analytical results from discrete soil and/or groundwater samples to collaborate direct-sensing data,
• Comparing on-site analytical data with traditional analytical methods,
• Collaborating lithology model with soil logs generated from existing or new soil borings,
• Integrating other site information (e.g. rectified fire insurance maps, historic maps, aerial photographs)

Exported data are symbolized based on site-specific criteria, e.g. state/federal regulations. All models, symbolized analytical data, fence diagrams, historic maps and other data sets become the final CSM. The relationship between these data sets comprises the full collaborative data set. Software can display data for these sites in 2-D or 3-D views, and provide a media for presenting these complex data to professional or non-professional stakeholders.

Data management tools, in conjunction with visualizing software, allow the end user to manage, visualize and analyze complex data sets associated with Triad projects. The Triad approach overcomes inherent complexities resulting from heterogeneity present at most environmental sites by utilizing real-time data sets incorporated into a dynamic work strategy. This develops a more accurate CSM with a higher density of data than traditional characterization methods. Rapidly entering correct data, and having that data instantly available for reports or exports to a variety of applications, allows an unparalleled pace of investigation and rapid analysis.

Successful implementation of the Triad approach holds great promise, and has been encouraged by many environmental scientists and regulators. The approach has a track record of reducing the timeframe for characterization, reducing uncertainty in designing engineering remedies, and reducing overall project life-cycle costs. It does this by providing a more accurate understanding of site conditions and thus resulting in better overall decision making for large- and small-scale projects. PE