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Title: Using the conceptual site model approach to characterize groundwater quality

Abstract

To understand groundwater quality, the first step is to develop a conceptual site model (CSM) that describes the site history, describes the geology and the hydrogeology of the site, identifies potential release areas or sources, and evaluates the fate and transport of site related compounds. After the physical site setting is understood and potential release areas are identified, appropriate and representative groundwater monitoring wells may be used to evaluate groundwater quality at a site and provide a network to assess impacts from potential future releases. To develop the CSM, the first step to understand the different requirements from each of the regulatory stakeholders. Each regulatory agency may have different approaches to site characterization and closure (i.e., different groundwater and soil remediation criteria). For example, the United States Environmental Protection Agency (EPA) and state governments have published guidance documents that proscribe the required steps and information needed to develop a CSM. The Nuclear Regulatory Commission (NRC) has a proscriptive model for the Historical Site Assessment under the Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM), and contains requirements for developing a conceptual site model in NUREG 1757. Federal and state agencies may also have different closure criteria for potential contaminants ofmore » concern. Understanding these differences before starting a groundwater monitoring program is important because the minimum detectable activity (MDA), lowest limit detection (LLD), and sample quantitation limit (SQL) must be low enough so that data may be evaluated under each of the programs. After a Historical Site Assessment is completed a work plan is developed and executed to not only collect physical data that describes the geology and hydrogeology, but to also characterize the soil, groundwater, sediments, and surface water quality of each potentially impacted areas. Although the primary purpose from operations management may be to address radionuclides in groundwater, the same steps are used to assess other potential contaminates of concern. Based on past experiences, each agency (and in turn the public interest groups) appreciate the initiative of an integrated approach. Use and coordination of the file search and investigative effort to understand potential impacts from all environmental impacts (radiological and chemical) will introduce cost savings and reduce the overall schedule for future projects. Be proactive and combine the initial programs to analyze samples for all appropriate chemical and radiological constituents. Because of the differences between the agencies, it is critical that there are ongoing discussions with all of the regulators. By developing a cohesive CSM, working together, sharing data, and being transparent during each step of the CSM development, there will be more trust, more public support and an easier and more efficient closure process if contaminated media are identified. The benefits of this approach include: - Trust with the regulators and the public. - EPA, state and NRC accepted base line evaluation. - Representative groundwater monitoring network. - Reduced number of points needed for long term monitoring. This paper discusses the process of using the CSM approach for groundwater contamination with examples from a variety of NRC licensed sites. (authors)« less

Authors:
; ;  [1]
  1. MACTEC, Inc., Portland, ME (United States)
Publication Date:
Research Org.:
WM Symposia, 1628 E. Southern Avenue, Suite 9 - 332, Tempe, AZ 85282 (United States)
OSTI Identifier:
21294645
Report Number(s):
INIS-US-09-WM-07086
TRN: US10V0054040835
Resource Type:
Conference
Resource Relation:
Conference: WM'07: 2007 Waste Management Symposium - Global Accomplishments in Environmental and Radioactive Waste Management: Education and Opportunity for the Next Generation of Waste Management Professionals, Tucson, AZ (United States), 25 Feb - 1 Mar 2007; Other Information: Country of input: France
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; CONTAMINATION; ENVIRONMENTAL IMPACTS; GROUND WATER; INFORMATION; MANUALS; MONITORING; RADIOACTIVE WASTES; REMEDIAL ACTION; SEDIMENTS; SITE CHARACTERIZATION; US EPA; WATER QUALITY

Citation Formats

Shephard, E., Glucksberg, N., and Walter, N.. Using the conceptual site model approach to characterize groundwater quality. United States: N. p., 2007. Web.
Shephard, E., Glucksberg, N., & Walter, N.. Using the conceptual site model approach to characterize groundwater quality. United States.
Shephard, E., Glucksberg, N., and Walter, N.. 2007. "Using the conceptual site model approach to characterize groundwater quality". United States. doi:.
@article{osti_21294645,
title = {Using the conceptual site model approach to characterize groundwater quality},
author = {Shephard, E. and Glucksberg, N. and Walter, N.},
abstractNote = {To understand groundwater quality, the first step is to develop a conceptual site model (CSM) that describes the site history, describes the geology and the hydrogeology of the site, identifies potential release areas or sources, and evaluates the fate and transport of site related compounds. After the physical site setting is understood and potential release areas are identified, appropriate and representative groundwater monitoring wells may be used to evaluate groundwater quality at a site and provide a network to assess impacts from potential future releases. To develop the CSM, the first step to understand the different requirements from each of the regulatory stakeholders. Each regulatory agency may have different approaches to site characterization and closure (i.e., different groundwater and soil remediation criteria). For example, the United States Environmental Protection Agency (EPA) and state governments have published guidance documents that proscribe the required steps and information needed to develop a CSM. The Nuclear Regulatory Commission (NRC) has a proscriptive model for the Historical Site Assessment under the Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM), and contains requirements for developing a conceptual site model in NUREG 1757. Federal and state agencies may also have different closure criteria for potential contaminants of concern. Understanding these differences before starting a groundwater monitoring program is important because the minimum detectable activity (MDA), lowest limit detection (LLD), and sample quantitation limit (SQL) must be low enough so that data may be evaluated under each of the programs. After a Historical Site Assessment is completed a work plan is developed and executed to not only collect physical data that describes the geology and hydrogeology, but to also characterize the soil, groundwater, sediments, and surface water quality of each potentially impacted areas. Although the primary purpose from operations management may be to address radionuclides in groundwater, the same steps are used to assess other potential contaminates of concern. Based on past experiences, each agency (and in turn the public interest groups) appreciate the initiative of an integrated approach. Use and coordination of the file search and investigative effort to understand potential impacts from all environmental impacts (radiological and chemical) will introduce cost savings and reduce the overall schedule for future projects. Be proactive and combine the initial programs to analyze samples for all appropriate chemical and radiological constituents. Because of the differences between the agencies, it is critical that there are ongoing discussions with all of the regulators. By developing a cohesive CSM, working together, sharing data, and being transparent during each step of the CSM development, there will be more trust, more public support and an easier and more efficient closure process if contaminated media are identified. The benefits of this approach include: - Trust with the regulators and the public. - EPA, state and NRC accepted base line evaluation. - Representative groundwater monitoring network. - Reduced number of points needed for long term monitoring. This paper discusses the process of using the CSM approach for groundwater contamination with examples from a variety of NRC licensed sites. (authors)},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2007,
month = 7
}

Conference:
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  • In natural subsurface systems dominated by heterogeneity, the delineation and even the detection of sparingly soluble, dense contaminants can be extremely difficult. The performance assessment of cleanup at these sites is therefore more complex. Several technologies for the characterization of sites contaminated with dense non aqueous phase liquids have recently been developed. These include geophysical techniques, tracer tests, and direct sampling or sensing methods.
  • The Conceptual Site Model (CSM) is a powerful tool for understanding the link between contamination sources, cleanup objectives, and ultimate site reuse. The CSM describes the site setting, geology, hydrogeology, potential sources, release mechanisms and migration pathways of contaminants. The CSM is needed to understand the extent of contamination and how receptors may be exposed to both radiological and chemical constituents. A key component of the CSM that is often overlooked concerns how the regulatory requirements drive remediation and how each has to be integrated into the CSM to ensure that all stakeholder requirements are understood and addressed. This papermore » describes how the use of the CSM helped reach closure and reuse at two facilities in Connecticut that are pursuing termination of their Nuclear Regulatory Commission (NRC) license. The two facilities are the Combustion Engineering Site, located in Windsor, Connecticut, (CE Windsor Site) and the Connecticut Yankee Atomic Power Company, located in Haddam Neck, Connecticut (CYAPCO). The closure of each of these facilities is regulated by four agencies: - Nuclear Regulatory Commission (NRC) - which requires cleanup levels for radionuclides to be protective of public health; - US Environmental Protection Agency (USEPA) - which requires cleanup levels for chemicals to be protective of public health and the environment; - Connecticut Department of Environmental Protection (CTDEP) Bureau of Air Management, Radiation Division - which requires cleanup levels for radionuclides to be protective of public health; and - Connecticut Department of Environmental Protection (CTDEP) Bureau of Water Protection and Land Reuse - which requires cleanup levels for chemicals to be protective of public health and the environment. Some of the radionuclides at the CE Windsor Site are also regulated under the Formerly Utilized Site Remedial Action Program (FUSRAP) under the Army Corps of Engineers. The remainder of this paper presents the similarities and differences between the CSMs for these two sites and how each site used the CSM to reach closure. Although each of these site have unique histories and physical features, the CSM approach was used to understand the geology, hydrogeology, migration and exposure pathways, and regulatory requirements to successfully characterize and plan closure of the sites. A summary of how these attributes affected site closure is provided.« less
  • A coupled adjoint-sensitivity/kriging approach was used to calibrate a groundwater-flow model to 10 years of human-induced transient hydraulic stresses at the WIPP site in New Mexico, USA. Transmissivity data obtained from local-scale hydraulic tests were first kriged to define an initial transmissivity distribution. Steady-state model calibration was then performed employing adjoint-sensitivity techniques to identify regions where transmissivity changes would improve the model fit to the observed steady-state heads. Subsequent transient calibration to large-scale hydraulic stresses created by shaft construction and long-term pumping tests aided in the identification of smaller scale features not detected during steady-state calibration. This transient calibration resultedmore » in a much more reliable and defendable model for use in performance-assessment calculations. 7 refs., 6 figs.« less
  • This paper proposes that: (1) the implicit assumptions forming the conceptual basis of today's subsurface water quality control requirements and evaluation guidelines are too simple, (2) such unrealistic simplicity means the present conceptual basis is incomplete, (3) the bottom-line result is incomplete, which leads to poor quality technical evaluations. Also, because of the simplified and incomplete conceptual basis, there are a continuing proliferation of control regulations and an ever growing stream of more complicated guidelines. Each guideline inacted to clarify the earlier flawed position. Such a Band-Aid over Band-Aid upon Band-Aid approach for covering the incomplete and too simplistic basismore » is doomed from the outset. The real solution lies in changing the incomplete basis and starting afresh with realistic regulations and key meaningful fundamental technical guidelines. 2 refs.« less
  • In 2004, Australia, through the Australian Nuclear Science and Technology Organisation (ANSTO), created the Regional Security of Radioactive Sources (RSRS) project and partnered with the U.S. Department of Energy’s Global Threat Reduction Initiative (GTRI) and the International Atomic Energy Agency (IAEA) to form the Southeast Asian Regional Radiological Security Partnership (RRSP). The intent of the RRSP is to cooperate with countries in Southeast Asia to improve the security of their radioactive sources. This Southeast Asian Partnership supports objectives to improve the security of high risk radioactive sources by raising awareness of the need and developing national programs to protect andmore » control such materials, improve the security of such materials, and recover and condition the materials no longer in use. The RRSP has utilized many tools to meet those objectives including: provision of physical protection upgrades, awareness training, physical protection training, regulatory development, locating and recovering orphan sources, and most recently - development of model security procedures at a model facility. This paper discusses the benefits of establishing a model facility, the methods employed by the RRSP, and three of the expected outcomes of the Model Facility approach. The first expected outcome is to increase compliance with source security guidance materials and national regulations by adding context to those materials, and illustrating their impact on a facility. Second, the effectiveness of each of the tools above is increased by making them part of an integrated system. Third, the methods used to develop the model procedures establishes a sustainable process that can ultimately be transferred to all facilities beyond the model. Overall, the RRSP has utilized the Model Facility approach as an important tool to increase the security of radioactive sources, and to position facilities and countries for the long term secure management of those sources.« less