Inventory of Performance Monitoring Tools for Subsurface Monitoring of Radionuclide Contamination

Transcription

1 Inventory of Performance Monitoring Tools for Subsurface Monitoring of Radionuclide Contamination H. Keith Moo-Young, Professor, Villanova University Ronald Wilhelm, Senior Scientist, U.S. EPA, Office of Radiation and Indoor Air Abstract Performance monitoring is directly linked to long-term stewardship. Performance monitoring is loosely defined in the literature, and needs stronger clarification for application to long-term stewardship. Performance monitoring involves the continuous or periodic measurement of the effectiveness of contaminant isolation systems once it has been employed. The term performance monitoring is often associated with the performance of physical systems. Monitoring is used to demonstrate the effectiveness of efforts to remove, treat or contain contamination. Environmental monitoring provides the information for periodic review and alteration of the environmental management plan as necessary, ensuring that environmental protection is optimized at all stages of the development through best practice. In addition, monitoring programs are not generic, off the shelf items that we place on a site. They must be specifically designed and developed for the site conditions. In this study, we inventoried the existing tools and technologies that could specifically be applied for subsurface monitoring at radioactive contaminated sites. Specifically, the technology inventory provides a brief description, application, cost and best practice. In addition, future technologies are highlighted. Introduction Environmental stewardship is defined as the set of activities necessary to protect human health and the environment from hazards posed by residual contamination and/or waste remaining at sites (or portions of sites) once cleanup is complete. Activities include: 1. Site monitoring and maintenance of engineered controls (surveillance activities, inspections, ongoing pump and treat activities, cap repair, maintenance of entombed buildings or facilities, and maintenance of other barriers and containment structures) 2. Application and enforcement of legal or other mechanisms (often referred to as institutional controls) to restrict land and water use, 3. Information management (record-keeping activities), 4. Environmental monitoring, 5. Contingency planning for emergency responses, 6. Failure trending and decision and risk analysis, 7. Enhanced environmental remediation or controls if required or beneficial Environmental restoration, waste disposal and facility stabilization activities are expected to be completed at many DOE sites in the near future. However, these sites may not be

2 cleaned up to a standard allowing unrestricted use. Many areas will require monitoring and maintenance to validate and ensure that the actions taken continue to be effective. Long-term stewardship, including soil and groundwater monitoring, record-keeping, and maintenance of containment structures, must continue (potentially for 30 years or more depending on the contaminant and the site conditions) to ensure the protection of human health and the environment. In addition, future scientific and engineering solutions will inevitably result in new opportunities for improving the effectiveness and lowering the costs of existing solutions. Performance Monitoring-GOAT- Governance, Objectives, Assessment, Tool/Technologies. Performance monitoring involves the continuous or periodic measurement of the effectiveness of contaminant isolation systems once it has been employed. Environmental monitoring provides the information for periodic review and alteration of the environmental management plan as necessary, ensuring that environmental protection is optimized at all stages of the development through best practices. In addition, monitoring programs are not generic, off the shelf items that we place on a site. They must be specifically design and developed specifically for the site conditions. The performance of the monitoring system is a key in defining if the stewardship activity is functioning appropriately. Performance monitoring criteria include the objective of the system, the spatial and temporal coverage of the site, the uncertainty of the parameters, and the range of applicability of various methods for network design. Performance monitoring is directly linked to the GOAT-Governance, Objectives, Assessment, and Tools/Technologies. Governance represents the regulations, regulatory authority, and the requirement for cleanup and remediation. The objectives of performance monitoring are typically established during the clean up process under Superfund and results from conceptual models. The key questions that must be answered in a regulatory framework are: 1. What is to be monitored? 2. Where, how, and how often monitoring is to occur? 3. What conditions would necessitate further actions? The assessment strategy employed for performance monitoring will have a direct impact on the cost of the project. There are several ways to assess performance of the monitoring network for a remedial effort. Systematic approaches have been proposed by numerous researchers. Ground water quality monitoring network design is defined as the selection of sampling sites and sampling frequency to determine the physical, chemical, and biological properties of groundwater. In this approach, the essential elements required to develop a monitoring network are as follows: 1. Establish the feasibility of monitoring,

3 2. Identify the monitoring goal, 3. Interpret the chemical and physical characteristics of the contaminant of concern and the likely mode of transport, 4. Interpret the characterization data. The two purposes of monitoring are to verify that the system being monitored is behaving as expected, and to compare monitoring results with pre-set limits for the purpose of standard verification. Conceptual modeling must be conducted before, during and after emplacement of the remediation system to establish the scientific baseline for what to expect on the site. Physical measurements are used post emplacement to verify the conceptual models. Tools and technologies for monitoring are the backbone of any monitoring network. Hundreds of specific methods and techniques exist for characterization, sampling, and monitoring of contaminated sites. 1 In this study, we aimed to summarize the existing data. For the presentation at the workshop, we provided details on the field and laboratory equipment pertinent to radiological contaminants. Multimedia Pathways and Monitoring Most engineering projects have a single primary technical objective that drives the design. Many projects must meet their objectives within a set of technical, legal, and political constraints. The objectives of performance monitoring are typically established during the clean up process under Superfund and results from conceptual models. In establishing the goals for a cleanup, risk reduction is of primary emphasis. The inherent goal of the monitoring system is to demonstrate that the selected remedy is performing as expected, detection of environmental conditions that may reduce the efficacy of the remedy, identify any potential toxic or mobile transformation products, and verify that the plume is not expanding. Multimedia and multi-pathway monitoring is not a new concept. However, the integration of multimedia and multi-pathway monitoring to conduct performance monitoring is a revolutionary concept. Advances in technology are reducing the cost of direct measurement. Surrogate monitoring provides a lower cost alternative to direct measurements for monitoring and analyzing data trends. Table 1 lists potential surrogates that can be monitored in the subsurface. 1 U.S. EPA. (1993). Subsurface Characterization and Monitoring Techniques: A Desk Reference Guide. Volume 1 and 2. EPA/625/R-93/003a and 003b.

4 Table 1 Surrogate Monitoring Parameters Soil Water Air Biology Bulk Density Wind Speed Ingestion Rates Particle Density Total Coliforms Humidity Bacteria Porosity Turbidity Barometric Portozoa Pressure Soil Water Tension Inorganics Temperature Helminths Field Capacity Soil Water Organics Volatile Organics Viruses Tension Residual Saturation Water Content ph Radionuclide DNA/geonomic Technology Infiltration Capacity Odor SO x Species Diversity Saturated Hydraulic Color NO x Plant Conductivity Soil Water Characteristic Corrosivity Particulate Matter Animal Curve Conductivity/Pressure Total Dissolved Mercury Soil to Plant Head Relationship Solids Transfer Factors Local Vertical Recharge Foaming Agents CO 2 Rate Specific Surface Area Chlorides UV Cation Exchange Radionuclides Precipitation Capacity Adsorption Coefficient Oxidation NH 3 Reduction Potential Diffusion Coefficient Color CO Organic Carbon Content Partitioning Coefficient Meteorological Data Partitioning Coefficient Constituent Ozone Chemical and Physical Properties Constituent Chemical and Constituent Lead Physical Properties Degradation Rate and Pathway Constituent Degradation Water balance Rate and Pathway

5 Inventory of Monitoring Technologies In this study, we conducted an inventory of monitoring technologies for subsurface applications. The following categories of technologies were evaluated: 1. Water Potential, 2. Water Content, 3. Saturated Hydraulic Conductivity, 4. Unsaturated Hydraulic Conductivity, 5. Groundwater Measurements, 6. Water Flux and Infiltration, 7. Groundwater Sampling Methods, 8. Remote Sensing, 9. Surface/Seismic, 10. Drilling and Solid Sampling, 11. Cone Penetration, 12. Geophysical Borehole, 13. Vadose Zone Soil/Solute and Gas Sampling and Monitoring Methods, 14. Chemical Field Screening and Analytical Methods, 15. Field Survey Equipment for Radiological Contaminants, 16. Laboratory Survey Equipment for Radiological Contaminants, For the purpose of this paper, we emphasize the results of field and laboratory survey equipment. Equipment Survey for Radiological Contaminants The equipment is divided into two broad groupings of field survey and laboratory instruments, and each group is subdivided into equipment that measures alpha, beta, gamma, x-rays, and radon. Information is provided in the appendix of the presentation for each system and includes its description, application and cost. Innovative technologies were also surveyed in this presentation. 2 Innovative technologies summarized in the appendix with a description, contaminant of interest, data of field trial, company, and cost 2 U.S. EPA. (2000). Multi-Agency Radiological Survey and Site Investigation Manual (MARSSIM). EPA 402-R