SAMPLING AND SURVEYING RADIOLOGICAL ENVIRONMENTS - CHAPTER 4 pot

61 CHAPTER 4 Sampling and Surveying Radiological Environments Environments that frequently require radiological sampling, direct measure- ments, and/or scanning include those associated with uranium mine sites, nuclear weapons production facilities, nuclear reactors, radioactive waste storage and dis- posal facilities, and areas in the vicinity of nuclear accidents. The primary objectives of sampling, direct measurements, and/or scanning performed in these environments include the following: • Defining the nature and extent of contamination; • Evaluating contaminant migration pathways; • Predicting rates of contaminant migration; • Assessing the risk to human health and the environment; • Evaluating cleanup alternatives; • Determining whether or not remedial action or decontamination and decommis- sioning objectives have been met; • Dispositioning of the waste material. One of the objectives of this chapter is to provide the reader with guidance on how to design cost-effective sampling programs that are both comprehensive and defensible. This guidance emphasizes the use of the EPA’s Data Quality Objectives (DQO) process (EPA, 1994a) to assist in the development of defensible sampling programs that meet all the sampling objectives. The DQO process requires one to state the problem clearly, identify the decisions that need to be resolved, identify inputs needed to resolve those decisions, specify data quality requirements (e.g., precision, accuracy, detection limits), define the temporal and spatial boundaries that apply to the study, define error tolerances (e.g., false positive, false negative, width of gray region), and develop a sampling design that meets these requirements. This chapter presents details on several useful statistical sample design software packages, guidance to assist the writing of a Sampling and Analysis Plan, and details on the most effective radiological scanning, direct measurements, and environmental media sampling methods available to support environmental studies. © 2001 by CRC Press LLC 62 SAMPLING AND SURVEYING RADIOLOGICAL ENVIRONMENTS 4.1 DESIGNING A DEFENSIBLE SAMPLING PROGRAM Each year, the EPA and the regulated community spend approximately $5 billion collecting environmental data for scientific research, regulatory decision making, and regulatory compliance. To ensure that these data are of sufficient quality and quantity to support defensible decisions, the process of collecting and analyzing data itself must be scientifically defensible. When designing a sampling program for an environmental study, the goal should be to collect data of sufficient quality and quantity to resolve all of the decisions that need to be made to complete the entire study. Since substantial cost is incurred with the mobilization and demobilization of a field sampling team, every effort should be made to perform all of the required sampling and analysis under one mobilization. Figure 4.1 identifies all of the key steps that are required to develop and imple- ment a defensible sampling program that supports the environmental decision- making process. This life-cycle process was modified after the process developed and implemented by Bechtel Hanford, Inc., Department of Energy, and EPA (1997). The following sections provide guidance on implementing each of the nine components of the data life cycle. If any one of the nine components is overlooked, the defensibility of the decision-making process will be severely impacted. 4.1.1 DQO Implementation Process Prior to implementing the seven-step EPA DQO process, a number of preparatory steps must first be implemented. These steps include holding a project planning Figure 4.1 Data life cycle. © 2001 by CRC Press LLC SAMPLING AND SURVEYING RADIOLOGICAL ENVIRONMENTS 63 meeting, performing a thorough scoping effort, holding interviews with the regula- tors who will be involved in the decision-making process, and holding a Global Issues Meeting to resolve any disagreements with the requirements specified by the regulators, or disagreements between two or more regulatory agencies. If these preparatory steps are not implemented prior to beginning the seven-step process, the seven-step process will drag on for weeks or months because all of the required information needed to support the process will not be available. 4.1.1.1 Planning Meeting The project manager should schedule and conduct a planning meeting with one or more technical advisors who have experience performing projects with a similar scope. The purpose of this meeting is to identify the project schedule, budget, staffing needs (DQO team), regulators, and procurement requirements. The size of the DQO team will vary between projects and is dependent upon the complexity of the problem. Examples of technical backgrounds that may be needed on the DQO team are provided in Section 4.1.5.1.3. The regulators are typically federal (e.g., EPA, NRC, DOE), state, and/or local regulators. Once the objectives of the planning meeting have been met, the project manager may begin the scoping process. 4.1.1.2 Scoping An essential component to designing a defensible sampling program is scoping. Scoping involves the review and evaluation of all applicable historical documents, records, data sets, maps, diagrams, and photographs related to process operations, spills and releases, waste handling and disposal practices, and previous environmen- tal investigations. The results from the scoping process are used in Step 1 (Section 4.1.1.5.1) of the DQO process to: • Identify the contaminants of concern (COCs); • Support the development of a conceptual site model; • Develop a clear statement of the problem. Since the results from the scoping process are used as the foundation upon which the sampling program will be designed, a project team should never attempt to rush through the scoping process in efforts to save money. Doing so could lead to the misidentification of the COCs, and the development of severely flawed conceptual site model and problem statement. The scoping checklist presented in Table 4.1 identifies the key elements that should be researched during the scoping process. Table 4.1 is designed to assist the project manager in assigning scoping items to individual team members and docu- menting the results. A site visit should be scheduled following the completion of the scoping effort to familiarize the project team with the current site conditions. In addition, interviews should be scheduled and performed to verify that the information © 2001 by CRC Press LLC 64 SAMPLING AND SURVEYING RADIOLOGICAL ENVIRONMENTS gathered during the scoping process is accurate, and to assist in filling in any informational data gaps. These interviews should include: • Historical site workers/managers/owners; • Federal, state, and/or local regulators; • Potentially responsible parties (PRPs). Interviews performed with federal, state, and/or local regulators should identify specific regulatory requirements that must be taken into consideration, and general concerns that they have related to the project. Examples of requirements and/or concerns expressed by regulatory agencies include: • Cleanup guidelines • Enforceable deadlines • Waste classification and disposal requirements • Preferred alternative actions for cleaning up the site • Favored sampling and/or survey methods Table 4.1 Scoping Checklist Project Title: Process Knowledge and Historical Information 1. Evaluation and Summary of Process Knowledge: Review historical records to identify the types of processes that were implemented at the site, the contaminants of concern, the types and estimated quantities of chemicals and radionuclides used, and any spills that may have occurred (note volume and type of chemical spilled). Person Assigned Responsibility: Summary: 2. Evaluation and Summary of Existing Information: Review all existing historical reports, analytical data, maps, diagrams, photographs, waste inventories, geophysical logs, drilling records, and other documents and/or records that could provide valuable information about the site under investigation. Person Assigned Responsibility: Summary: Regulatory Issues 1. Identify All Applicable Regulatory Guidelines: Review regulations and agreements for the purpose of defining all applicable standards or risk-based guidelines for the various types of environmental media (e.g., groundwater, surface water, soil, air) that may be impacted at the site. Person Assigned Responsibility: Summary: 2. Identify all Agreements, or Regulatory/Statutory Obligations and Constraints: Identify all previously agreed upon milestones with regulatory agencies, waste acceptance criteria, and Applicable or Relevant and Appropriate Requirements (ARARs). Identify what regulatory pathway should be followed (e.g., RCRA, CERCLA, NEPA). Person Assigned Responsibility: Summary: 3. Identify All Regulatory Issues Pertaining to Waste Management: Identify Land Disposal Restrictions (LDR) that apply to waste material derived from the site. Identify waste acceptance criteria for potential waste disposal facilities. Person Assigned Responsibility: Summary: © 2001 by CRC Press LLC SAMPLING AND SURVEYING RADIOLOGICAL ENVIRONMENTS 65 4.1.1.3 Regulator Interviews The regulators for a project may include federal (e.g., EPA, NRC, DOE), state, and/or local representatives who are responsible for making decisions on issues such as cleanup guidelines, deliverable milestone dates, waste classification and disposal requirements, preferred remedial alternatives, and/or favored sampling methods. Prior to the commencement of the DQO process, the project manager should contact federal, state, and local regulatory agencies to identify the names of the Cultural Issues 1. Identify All Cultural Issues That Must Be Taken into Consideration: Identify any Native American populations that may be impacted (e.g., burial grounds), or other cultural related issues that should be taken into consideration. Person Assigned Responsibility: Summary: Ecological Risk Assessment Issues 1. Identify All Ecological Issues That Must Be Taken into Consideration: Identify any threatened or endangered species of plants or animals that may be present in the vicinity of the site. Identify the potential contaminant sources, pathways, and receptors. Person Assigned Responsibility: Summary: Human Health Risk Assessment Issues 1. Identify All Human Health Concerns Associated with the Site: Use the identified existing information to perform a preliminary assessment of all potential chemical, radiological, and physical health hazards that may be encountered at the site. Identify the potential contaminant sources, pathways, and receptors. Person Assigned Responsibility: Summary: Other Issues 1. Identify Potential Data Uses: Identify all of the potential uses for existing or new analytical data. These uses may include defining the nature and extent of contamination, risk assessment, feasibility studies, treatability studies, remedial design, postremediation confirmation sampling, etc. Person Assigned Responsibility: Summary: 2. Identify Sampling, Surveying, and/or Analytical Methods That Should Be Considered: Identify sample collection methods, field surveying methods, on-site laboratory methods, and laboratory methods that should be taken into consideration. Provide advantages and disadvantages to using each method, and general performance capabilities (e.g., detection limits, precision, accuracy). Person Assigned Responsibility: Summary: 3. Identify Potential Risk Assessment Models That Should Be Considered: Provide the name of each model (e.g., RESRAD), the input requirements (e.g., Ra-226 activity levels in surface soil), and advantages and disadvantages of each. Person Assigned Responsibility: Summary: Table 4.1 (continued) Scoping Checklist © 2001 by CRC Press LLC 66 SAMPLING AND SURVEYING RADIOLOGICAL ENVIRONMENTS representatives who will be involved with the project. Once the regulators have been identified, a 1- to 2-h interview should be scheduled with each of them individually. The purpose of the interview is to identify all of the key issues of concern that will need to be addressed by the DQO process. The project manager should consider bringing a few key technical experts to the regulator interviews to answer any technical questions that may arise. 4.1.1.4 Global Issues Meeting A Global Issues Meeting is held whenever there are disagreements with any of the requirements specified by the regulators, or when the requirements from one regulator contradict the requirements of one of the other regulators. For example, the federal regulator may require the site under investigation to be remediated in accordance with the CERCLA process, while the state regulator may require the site to be remediated in accordance with the RCRA process. This meeting should be attended by the project manager, key technical project staff, and all of the regulators. All agreements made at the conclusion of the Global Issues Meeting should be carefully documented in a memorandum that is then entered into the document record. 4.1.1.5 Seven-Step DQO Process The seven-step DQO process is a strategic planning approach developed by the EPA (EPA, 1994a) to prepare for data collection activities. This process provides a systematic procedure for defining the criteria that a data collection design should satisfy, including when/where/how to collect samples/measurements, tolerable limits on decision errors, and how many samples/measurements to collect. One of the advantages of the DQO process is that it enables data users and relevant technical experts to participate in the data collection planning process, where they can specify their specific data needs prior to data collection. The DQO process should be implemented during the planning stage of an inves- tigation prior to data collection. Using this process will ensure that the type, quantity, and quality of the environmental data used in the decision-making process will be appropriate for the intended application. The DQO process is intended to minimize expenditures related to data collection by eliminating unnecessary, duplicative, or overly precise data. In addition, the DQO process ensures that resources will not be committed to data collection efforts that do not support a defensible decision. The DQO process consists of the seven steps identified in Figure 4.2. The output from each step influences the choices that will be made later in the process. Even though the DQO process is depicted as a linear sequence of steps, in practice, the process is iterative. In other words, the outputs from one step may lead to reconsid- eration of prior steps. This iterative approach should be encouraged because it will ultimately lead to a more efficient data collection design. During the first six steps of the process, the DQO team will develop the decision performance criteria, otherwise referred to as DQOs. The final step of the process involves developing the data collection design based on the DQOs. © 2001 by CRC Press LLC SAMPLING AND SURVEYING RADIOLOGICAL ENVIRONMENTS 67 The first six steps must be completed prior to developing the data collection design. In Figure 4.2, the iterative link between DQO Steps 1 through 6 and DQO Step 7 “Optimize the Design” is illustrated by double arrows, which signify that it may be necessary to revisit any one or more of the first six steps to develop a feasible and appropriate data collection design. The DQO workbook template found in Appendix A and the accompanying CD-ROM should be used to help the user implement the DQO process. This workbook was developed as a joint effort between the author and Bechtel Hanford, Inc., technical staff. The results from the DQO process should then be used to support the preparation of a Sampling and Analysis Plan (see Section 4.1.1.7). The key activities that are performed for each of the seven steps are summarized in Table 4.2. A more-detailed discussion of each of these steps is presented in the following sections. 4.1.1.5.1 Step 1: State the Problem Objective: To define the problem clearly so that the focus of the project will be unambiguous. Activities: • Identify task objectives and assumptions. • Identify members of the DQO team. • Identify the regulators. • Specify budget requirements and relevant deadlines. • Identify the contaminants of concern. • Develop conceptual site model. • Develop a concise statement of the problem. Figure 4.2 Seven steps that comprise the DQO process. © 2001 by CRC Press LLC 68 SAMPLING AND SURVEYING RADIOLOGICAL ENVIRONMENTS Table 4.2 DQO Seven-Step Process DQO Step No. Activities Step 1: State the Problem • Identify the contaminants of concern • Develop a conceptual site model • Formulate a concise problem statement Step 2: Identify the Decisions • Identify the principal study questions (PSQs) that the study will attempt to resolve • Identify the alternative actions that may result once each of the PSQs has been resolved • Join the PSQs and alternative actions to form decision statements Step 3: Identify Inputs to the Decisions • Identify the information needed to resolve each decision statement • Determine the source and level of quality for the information needed • Determine whether or not data of adequate quality already exist Step 4: Define the Study Area Boundaries • Define the population of interest and the geographic area/volume to which each decision statement applies • Divide the population into strata (statistical) that have relatively homogeneous characteristics • Define the temporal boundaries of the problem — Time frame to which each decision applies — When to collect the data • Define the scale of decision making Step 5: Develop Decision Rules • Define the statistical parameter of interest (e.g., mean) • Define the final action level • Develop decision rules which are “if … then … ” statements that incorporate the parameter of interest, scale of decision making, action level, and alternative actions that would result from the resolution of the decision Step 6: Specify Limits on • Select between a statistical and nonstatistical sample design: Decision Errors — Define the expected concentration range for the parameter of interest — Identify the two types of decision error — Define the null hypothesis 1. Define boundaries of the gray region 2. Define tolerable limits for decision error Step 7: Optimize the Sampling Nonstatistical Design: Design • Provide summary of applicable surveying method alternatives • Provide summary of applicable sampling method alternatives • Develop an integrated sampling design Statistical Design: • Identify statistical sampling design alternatives (e.g., simple random, stratified random) and select the preferred alternative • Select the statistical hypothesis test for testing the null hypothesis • Evaluate multiple design options by varying the decision error criteria and width of the gray region • Select the preferred sampling design © 2001 by CRC Press LLC SAMPLING AND SURVEYING RADIOLOGICAL ENVIRONMENTS 69 Outputs: • Administrative and logistical elements • Concise statement of the problem 4.1.1.5.1.1 Background — In the process of defining the problem to be resolved, a combination of administrative and technical activities needs to be performed. The administrative activities include identifying the project objectives and assumptions, identifying the members of the DQO team and the regulators, and specifying budget requirements and relevant deadlines. The technical activities include identifying the contaminants of concern, developing a conceptual site model, and developing a concise statement of the problem. 4.1.1.5.1.2 Identify Task Objectives and Assumptions — This activity involves the development of a clear statement of the task objectives as they pertain to remedial activities. Initially identify the objectives on a large scale; then focus on the task- specific objectives. Identify all of the task-specific assumptions that have been made based on DQO team discussions and interviews with the regulators. 4.1.1.5.1.3 Identify Members of the DQO Team — The project manager iden- tifies the members of the DQO team in the planning meeting (Section 4.1.1.1). The DQO team should be composed of technical staff members with a broad range of technical backgrounds. The number of members on the team should be directly related to the size and complexity of the problem. Complex tasks may require a team of ten or more members, while simpler tasks only require a few members. The required technical backgrounds for the DQO team members will vary depending on the scope of the project, but often include: • Radiochemistry • Hydrogeology • Environmental engineering • Radiation safety • Statistics • Groundwater/surface water/air modeling • Quality assurance • Waste management • Risk assessment • Remedial design 4.1.1.5.1.4 Identify the Regulators — The project manager identifies the regula- tors in the planning meeting (Section 4.1.1.1). Regulators are those who have authority over the study, and are responsible for making final decisions based on the recommendations of the DQO team. The regulators are often representatives of: • Department of Energy • Department of Defense • Nuclear Regulatory Commission © 2001 by CRC Press LLC 70 SAMPLING AND SURVEYING RADIOLOGICAL ENVIRONMENTS • Environmental Protection Agency • State regulatory agencies • Local regulatory agencies The project manager should encourage early regulator involvement since this will help ensure that the task stays on track. 4.1.1.5.1.5 Specify Budget Requirements and Relevant Deadlines — The project manager identifies the budget requirements and relevant deadlines in the planning meeting (Section 4.1.1.1). The specified budget requirement should include the cost for: • Implementing the DQO process • Preparing a DQO Summary Report • Preparing a Sampling and Analysis Plan • Implementing sampling activities • Performing laboratory analyses • Performing data verification/validation • Performing data quality assessment • Evaluating the resulting data Identify all deadlines for completion of the study and any intermediate deadlines that may need to be met. 4.1.1.5.1.6 Develop a Conceptual Site Model — A conceptual site model is either a tabular or graphical depiction of the best understanding of the site conditions. The process of developing a conceptual site model helps one to identify any data gaps that may exist. The conceptual site model should identify: • Primary and secondary sources of contamination • Release mechanisms • Pathways for contaminant migration • Routes for exposure • Receptors In the example provided in Table 4.3 and Figure 4.3 the primary and secondary sources of contamination are the piles of chipped radiologically contaminated metal and the contaminated soils/sediment/water (surface water/groundwater) in the vicin- ity of the chipped metal piles, respectively. The contaminated metal chips were brought on site by railcar from another contaminated location. The contamination from the metal chips migrated into the surrounding soil, and was carried by surface water to a small nearby pond. Contamination was also transported by groundwater to a nearby drinking water well. The release mechanisms include wind, rain, pumping groundwater from the drinking water well, and/or human receptors walking through the contaminated area. The pathways for contaminant migration include air, surface © 2001 by CRC Press LLC [...]... include: • • • • • • • U-238, Ra-226, Th-230, and Th-232 activity levels in shallow and deep soil; Metals concentrations in shallow and deep soil; U-238, Ra-226, Th-230, and Th-232 activity levels in surface water; Metals concentrations in surface water; U-238, Ra-226, Th-230, and Th-232 activity levels in groundwater; Metals concentrations in groundwater; Fixed and removable gross alpha and gross beta/gamma... by CRC Press LLC 92 SAMPLING AND SURVEYING RADIOLOGICAL ENVIRONMENTS 4. 1.1.5.7.2.1 Simple random sampling — When little historical information about the site exists, simple random sampling is a good choice Simple random sampling is implemented by dividing the site into possible sampling units (i.e., the area that will be represented by a single sample) A site may be divided into sampling units by overlaying... that for other sampling strategies 4. 1.1.5.7.2.2 Stratified random sampling — When historical information provides sufficient detail to partition the site into relatively homogeneous, nonoverlapping areas or strata, stratified random sampling is superior to simple random sampling Sampling units are created and numbers assigned to sampling units in the same manner as with simple random sampling However,... or more cleanup guidelines and requires removal and disposal in a radiological landfill, or if no action is required © 2001 by CRC Press LLC 74 SAMPLING AND SURVEYING RADIOLOGICAL ENVIRONMENTS 4. 1.1.5.3 Objective: Step 3: Identify Inputs to the Decisions To identify the informational inputs that will be required to resolve the decision statements identified in DQO Step 2, and to determine which inputs... next step is to identify all potential surveying technologies and/ or judgmental sampling methods that could potentially be used to provide the required data for each type of media (e.g., soil, concrete, paint) Sections 4. 2 through 4. 5 provide a number of scanning, direct measurement, and sampling methods that should be taken into consideration The identified surveying and sampling methods should then... problem (breaking it into more manageable pieces) Figures 4. 4 and 4. 5 provide examples of how two different sites may be stratified The stratification approach presented in Figure 4. 4 is based on current and past land use, while the stratification approach presented in Figure 4. 5 is based on a site inspection or preliminary data results 4. 1.1.5 .4. 3 D e fi n e t h e Te m p o ra l B o u n d a r y o f E a... 2001 by CRC Press LLC 94 SAMPLING AND SURVEYING RADIOLOGICAL ENVIRONMENTS when determining what remedial alternative is most appropriate, or when modeling contamination transport When using geostatistical sampling, historical data are needed so that the two- or three-dimensional correlation patterns may be established Samples are then collected to augment historical data and fine-tune the gradations in... judgmental sampling design 4. 1.1.5.7.2 Statistical Designs — The purpose of this section is to provide general information on statistical sampling concepts Reference is made to commonly used statistical hypothesis tests and formulae for calculating the number of samples required and confidence limits However, this section is not intended as a technical © 2001 by CRC Press LLC 88 SAMPLING AND SURVEYING RADIOLOGICAL. .. to have radiologically contaminated soil in the backyard, the time frame to which a decision related to the risk condition of an average resident may be set at 8 years if that were the average length of residence for one family in the home © 2001 by CRC Press LLC 78 SAMPLING AND SURVEYING RADIOLOGICAL ENVIRONMENTS Figure 4. 4 Example 1 of site stratification based on current/past land use Figure 4. 5 Example... these data cannot be evaluated statistically Even when performing site © 2001 by CRC Press LLC SAMPLING AND SURVEYING RADIOLOGICAL ENVIRONMENTS 87 characterization activities, judgmental sampling should be combined with one or more statistical sampling approaches (e.g., simple random sampling, systematic sampling) since these data are often needed to support risk calculations, modeling studies, etc . these vari- ables include: • U-238, Ra-226, Th-230, and Th-232 activity levels in shallow and deep soil; • Metals concentrations in shallow and deep soil; • U-238, Ra-226, Th-230, and Th-232 activity. 61 CHAPTER 4 Sampling and Surveying Radiological Environments Environments that frequently require radiological sampling, direct measure- ments, and/ or scanning include. guidelines and requires removal and disposal in a radiological landfill, or if no action is required. Figure 4. 3 Graphical depiction of a conceptual site model © 2001 by CRC Press LLC 74 SAMPLING AND SURVEYING