Summary of the Report
This is a critical appraisal of the NDA RWMD Geosphere Characterisation Project. The critical appraisal involves a thorough assessment of a report paper to determine the focus or objectives of the study, validity, and reliability of the study methods, the validity of results and generalization of findings to other similar projects. It also shows the contribution of new scientific knowledge that the report adds to the field of groundwater sampling and analysis techniques. Any report that fails critical appraisal processes remains skeptical and therefore not reliable.
It is noteworthy that the report provides a comprehensive summary of the study. It identifies the organization that commissioned the study as the NDA and provides the purpose as a trustworthy review of groundwater sampling and analysis techniques that can be applied in any site characterization project for a geological disposal facility for higher activity radioactive waste (Quintessa Limited 2008). The report further indicates specific three hydrogeological environments that were considered during sampling as fractured crystalline rock, quartz-rich porous rock, and mudstone. From these three hydrogeological environments, the report shows that groundwater can move in the first two forms of the environment but cannot move in the last one because of pore water contained.
It also accounts for different types of technologies used during sampling in both shallow (less than 100 m) and deep (up to 200 m) boreholes for groundwater and details any volatile hydrochemical elements such as redox, pH and dissolved oxygen (DO).
The report also considers the probable quality of sampled water based on representative characteristics of groundwater conditions. It further identifies challenges such as equipment diameter, water volume obtained as well as the collected sample pressure status during sampling procedures. Challenges were also witnessed in finding the best technology tools for groundwater sampling and hydrochemical monitoring because the available ones are for oilfield use or specially constructed tools for use in other regions. Recommendations were made for such tools.
The report also described different procedures used to obtain data for pore water elements in mudstones, matrix of crystalline rocks and quartz-rich porous rock (Quintessa Limited 2008). It was shown that the procedures were developed to meet the unique features of a given site and underground laboratory programs. The methods applied entailed obtaining pore water and solutes from drillcores. Specially designed equipment is required for extraction through leaching and/or squeezing.
Few facilities with such specialized equipment are available in Europe, and recommendations are made based on these observations if the UK wishes to analyze pore water contents.
The report concluded that the UK currently lacks capacity, experience and a strong base of capability to handle groundwater sampling requirements. Hence, it cannot meet the NDA specifications. In this regard, the report shows that the UK should cooperate with other nations with capabilities, technologies, and capacities to acquire equipment and experiences that can meet its unique characteristics in groundwater sampling. A lack of facility upgrades could present serious challenges to UK and capacity could be a problem for site characterization projects because of the necessary resources, including experienced human resources and facilities. There is widespread competition for experienced staff all over Europe for new and ongoing projects.
The report covers analytical methods used in the project. It shows data on sample volume used, potential detection limit, accuracy, and standards. In the report, it is evident that several analyses were performed, including normal solute analyses to more complex, specialized analyses that involved environmental isotopes, dissolved gas, and microbes among others. The report also provides a detailed conclusion of the study. It shows that a facility in the UK for a site characterization program for geological disposal would require a substantial amount of planning and capacity building of analysts, specialized sampling equipment and methods, as well as preparation of analytical methods required. A lack of these vital facilities would require cooperation and collaboration with other countries to conduct site characterization research programs and analyses. Capacity and capability development for water sampling and analysis requires adequate time, and it could be longer than two years for technical analytics.
Groundwater sampling and analysis techniques
Introduction
This is a critical appraisal of the NDA RWMD Geosphere Characterisation Project. Generally, it involves the systematic assessment of various elements of the report to establish whether the objectives and questions of the study are relevant; supporting literature; the validity of the study methods and analytical techniques; the validity of the results; applicability of results; conclusion; recommendation; and new knowledge the report adds to the field of groundwater sampling and analysis techniques. A report that fails to meet some of the above-mentioned areas and scientific rigor may not serve its intended purposes.
It is imperative to note that reports have specific purposes and therefore contents may vary accordingly. Nevertheless, there are fundamental elements such as objectives, scope, literature review methodology, sampling, and conclusion among others that are found in most reports. Various organizations such as Environment Protection Authority, Australia and the US Environmental Protection Agency (Environment Protection Authority 2000; Barcelona, Gibb, Helfrich, & Garske 1985), researchers (Kumar, n.d), and professional bodies (Geosphere, Inc. 2006) have provided different contents found in their studies and reports.
Scope
The UK Government has focused on managing radioactive wastes through the Managing Radioactive Waste Safely (MRWS) project, which has reached its fourth stage now. The fourth stage focuses on the implementation of the selected option for long-term management of high-level and intermediate level (HLW and ILW) wastes. The most preferred method is the construction of a new geological disposal facility and members of the community are invited to participate by expressing interests to host the facility in their locality.
In reaction to the Government’s announcement to select the appropriate size for the facility, the NDA opted to commence a process of characterizing a suitable site or sites that meet the preliminary screening criteria. It is imperative to note that different other radioactive waste materials, including plutonium, spent fuel and uranium are potential candidates for disposal in the proposed site.
A report should clearly identify the scope of the study. In this report, a detailed scope has been provided to guide the assessment and readers. It covers the following:
- Equipment for obtaining high-quality water samples from shallow and deep boreholes
- Availability and suitability evaluation for equipment for obtaining high-quality groundwater samples
- Procedures and apparatus for handling water samples during transfers to laboratories
- Appropriate technologies used to acquire and handle volatile geochemical elements
- Extraction techniques for pore water from different rock samples
- A discourse on hydrochemical elements that can be evaluated at the site laboratory
- Analytical techniques covering standards, certain quality criteria, and laboratory availability
With such a well-defined scope, readers of the report can identify the vision of the program. It highlights the goal, program deliverables and shows what is expected after a successful program.
The most vital data sets for characterizing the geosphere at any possible disposal facility should be obtained from isotopic and hydrochemical parameters. For optimal analyses, enough groundwater samples with the best obtainable quality must be selected.
The report identifies difficulties associated with the groundwater sampling. These are mainly remoteness of the downhole, pressure and hydraulic factors that influence water mixing during extraction. Deep borehole sampling is difficult in low permeable rock formations due to low rates of water flow from the rocks.
Further, the report points out that no ‘ideal’ techniques and tools for sampling that can warrant success. Hence, process optimization is necessary but it needs suitable equipment, effective quality control, and process monitoring to ensure that the best possible groundwater sample is collected and analyzed.
A wide range of sampling techniques and technologies are discussed in the report. They differ based on borehole characteristics, analytical needs, and several other commercial and logistical challenges. The report strives to highlight the capabilities of various technologies and certain tools and show commercial availability and several cost variables.
Groundwater sampling for deep boreholes to the expected standards is not a common practice in the UK, and the required tools for specific needs are usually rare or not available at all. Hence, the report presented a real scenario with the equipment availability, indicative costs, usability, and constraints.
The report identified various sampling techniques that were applied to extract isotopic and hydrochemical data for pore water from the target rocks with extremely poor permeability or mudstones. The most suitable sampling procedures were selected for various types of rocks. The report further showed related limitations with various forms of parameter and data reliability. Measurements for various hydrochemical elements may be conducted either in the borehole or at the surface of the borehole. Redox potential (Eh) and pH must be evaluated to determine the best conditions.
Analytical techniques are covered in this report. In fact, the report lists all analytical techniques to evaluate groundwater samples used.
Some additional parameters were included in various lists of hydrochemical and isotopic data to ensure completeness. That is, they could show a complete set of the required variables for various small sub-sets of all collected water samples and different sub-sets could be chosen because of their sample reliability. Techniques used for samples differed based on specific sample requirements, quality, and objective relevance. Overall, the report covered information that was used in analytical methods and was related to analytical precision, sample requirements, procedures, and analytical costs.
Finally, the report scope also accounted for various groundwater sample processing and transfer techniques that were required for sample transfer to laboratories from any sites.
Objective
A good report must provide the objectives of a program. In this report, the objective was provided and it aimed to offer “NDA-RWMD with an authoritative review of groundwater sampling and analytical techniques which could be used as part of a site characterization program for the investigation of a potential geological disposal facility for higher activity radioactive waste” (Quintessa Limited 2008).
In this report, the program objective provided a concrete statement with the elements that the program strived to achieve. It was documented so that it can be reviewed at the end of the study to determine the program success.
This report also outlines the organization of the report. Different sections are shown with relevant content.
Supporting evidence or other relevant studies used in the report
In most cases, programs use supporting evidence or focus on literature review to provide credibility, identify gaps and show areas for improvements. Some reports, reports or guidelines have a clear section for literature review (Kumar n.d; Barcelona et al. 1985).
Although this report did not provide a section for the literature review, it is necessary to emphasize that other supporting materials or works of other researchers were used in this report. On this note, a reference page for all cited materials was included in the report. This approach is evident in other reports in the same field (Geosphere, Inc. 2006; Environment Protection Authority 2000).
Sampling and Analytical Methods for Groundwater
Specialized laboratories for specific analyses were used in the project. It is not possible to have a single analytical center for all analytical requirements involved. Analytical requirements need integration and coordination of different methods and laboratories to handle sampling, preservation, and processing for analysis. The current facilities and skills in the UK cannot adequately cover some analytical requirements. Hence, the UK must develop the necessary expertise and facilities to handle related analytical tasks. It is cucumber to ship some samples for longer distances. While some laboratories may be in the UK, they already handle different forms of works and creating new systems to handle unique analyses could be difficult because of expertise, equipment requirements, training, sample testing, and final analyses.
The report presents the main objectives of the groundwater sampling and analyses in site characterization within the context in which data may be applied in making decisions to select the most suitable place for the siting and safety of the facility. Moreover, it provides further details on certain hydrochemical and isotopic data requirements in the appendix for readers. The objective of this report was used to determine the best criteria that would be used to select the most appropriate sampling and analytical techniques that could result in high confidence during data analysis and interpretation.
Several factors that influenced the choices of sampling methods for different types of rocks are identified in this report. The rock types that were identified in the report included “fractured crystalline rock, quartz-rich porous rock, and mudstones” (Quintessa Limited 2008). It is imperative to observe that the report also presented measures and controls that were taken to ensure that high-quality water samples were obtained to be the representative of in situ groundwater composition. It further offers relevant information on general water volumes of samples and their relationships to analytical standards. In 1991 and 1994, two studies were conducted in the same location but yielded different results (Ivahnenko, Szabo, & Gibs 2001). Ivahnenko et al. (2001) concluded that the differences in groundwater elements such as copper, lead, zinc, and manganese emanated from low attention observed during sample handling.
The report provided various fluid sampling technologies used for both shallow boreholes and deep boreholes. It is noted that various sampling technologies are required for different types of rock formations. Only specific boreholes with certain depth characteristics and show adequate transmissivity were considered based on porosity and fractures. Some studies have shown that sampling techniques may be modified based on prevailing ground conditions and the need to obtain quality representative samples (Barker & Dickhout 2007). Some of the methods used in these processes include “downhole samplers, open-hole pumping, dual-packer discrete interval sampling tools, and sidewall testing” (Quintessa Limited 2008). These methods accounted for different parameters such as physical characteristics of equipment; sampling methods; volume; preservation of situ pressure; measurement limitations; and costs and commercial availability of equipment. These factors are observed for deeper insights and they enhance the mass balance accuracy of groundwater samples (McLeish, Ryan, & Chu 2008).
This report further provides different sampling techniques that may be effective for NDA for site characterization programs based on the geological situations in the UK, time and developments necessary for skills and capabilities.
The report also covers the best procedures for acquiring the best possible data for several volatile elements, specifically Eh and pH. Only a single tool for deep downhole examination and with the capabilities to collect and record results was available. Surface pumping and initiating electrode measurements was also identified as an alternative method for several diverse situations. Sampling techniques and methods were considered based on several characteristics. These included physical characteristics and standards; pH, Eh, dissolved gas, temperature, and electrical conductivity; accuracy and precision; measurement constraints; and commercial availability and expected costs. Downhole probe equipment for deep borehole examination is not commercially available in the UK.
Special methods for obtaining hydrochemical and isotopic data for pore water in extremely low permeable rocks are also discussed in the report. It also includes basic data acquisition from fractured crystalline rocks and quartz-rich porous rocks. It was noted that some samples required laboratory-based processes to obtain samples from the available pore water using different methods that were developed for necessary analyses. Sampling is a complex process that few laboratories globally have the necessary equipment to handle globally. Some of the technologies used are now well developed and established, but few laboratories with equipment have been located. The report further provides advice on technical strategies that can be applied during the NDA program investigation. It accounts for methods used to estimate salinity in different rock samples.
The report also provides how on-site laboratories can be used to analyze some elements. These are the main parameters, which can only be manipulated or can be measured for real-time based results for sample quality. With a site laboratory, other analyses may be conducted on the site. In these cases, considerations are mainly analyzed methods and equipment; the need for on-site analysis; the effectiveness of alternative analyses; accuracy and precision; costs and availability of equipment for sale.
Given the nature of the study, the report also covers information related to standards, techniques, logistics needed for off-site analyses of isotopic, and hydrochemical elements. They are based on generally-available specifications and methods, but modifications may be required to account for some ultra-trace elements (Ivahnenko et al. 2001) or analyses in extremely saline water samples. It is imperative to note that some of these analyses require highly specialized, expensive laboratories, which may not be easily available. Factors considered for these types of analyses include analytical techniques and equipment; facility accreditation; detection potential, accuracy and precision; and general commercial availability and costs. On such issues, the report offers the best advice for NDA to consider, but within the analytical capabilities of existing facilities in the UK. Alternatively, it shows that the UK can acquire facilities and develop capacities to handle such analytical requirements.
Finally, the report provides a summary of all major sampling and analytical techniques and shows primary issues that are most likely to occur when acquiring samples and conducting analyses for groundwater site investigation.
Conclusion
From a critical perspective, one can conclude that the report achieved its objective to “provide NDA-RWMD with an authoritative review of groundwater sampling and analytical techniques which could be used as part of a site characterization program for the investigation of a potential geological disposal facility for higher activity radioactive waste” (Quintessa Limited 2008).
Several analytical techniques and sampling methods for groundwater are covered to account for different site characteristics and the quality of the extracted sample water. It is noted that methods and analytical techniques could be modified to meet unique sample or site characteristics. However, no techniques are shown to be extremely effective.
The report further provides information on critical factors to be considered for specific sampling and analytic methods, which could be difficult to perform in the UK, are expensive, or require special equipment and expertise.
Overall, it is a good report that can be applied in other works of similar nature, but modifications must be observed to avoid common errors.
Reference List
Barcelona, MJ, Gibb, JP, Helfrich, JA & Garske, EE 1985, Practical Guide for Ground-Water Sampling, U.S. Environmental Protection Agency, Illinois.
Barker, J & Dickhout, R 2007, ‘An Evaluation of Some Systems for Sampling Gas-Charged Ground Water for Volatile Organic Analysis’, Groundwater Monitoring & Remediation, vol. 8, no. 4, pp. 112-120. Web.
Environment Protection Authority 2000, Groundwater Sampling Guidelines, Environment Protection Authority, Australia.
Geosphere, Inc. 2006, Groundwater Sampling Techniques for Site Characterization and Hydrocarbon Risk Calculations, Web.
Ivahnenko, T, Szabo, Z. & Gibs, J 2001, ‘Changes in sample collection and analytical techniques and effects on retrospective comparability of low-level concentrations of trace elements in ground water’, Water Research, 35(15), pp. 3611–3624. Web.
Kumar, CP n.d., Groundwater Data Requirement and Analysis.
McLeish, K., Ryan, C & Chu, A 2008, ‘Integrated sampling and analytical approach for common groundwater dissolved gases’, Environmental Science and Technology, vol. 41, no. 24, pp. 8388-93. Web.
Quintessa Limited 2008, NDA-RWMD Geosphere Characterisation Project-Data Acquisition Report: Groundwater Sampling and Analysis Techniques, Nuclear Decommissioning Authority, United Kingdom.