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Title: Reaching site closure for groundwater under multiple regulatory agencies

Groundwater at the Connecticut Yankee Atomic Power Company (CYAPCO) Haddam Neck Plant (HNP) has been impacted by both radionuclides and chemical constituents. Furthermore, the cleanup standards and closure requirements for HNP are regulated both by federal and state agencies. The only consistent requirement is the development of a site conceptual model and an understanding of the hydrogeologic conditions that will govern contaminant transport and identify potential receptors. The cleanup criteria to reach site closure for radionuclides is regulated by both the Nuclear Regulatory Commission (NRC) and the Connecticut Department of Environmental Protection (CTDEP) Bureau of Air Management, Radiological Division. For license termination under the NRC, the total effective dose equivalent (TEDE) for all media can not exceed 25 milli-Rem per year (mRem/yr) plus As Low as Reasonably Achievable (ALARA). The CTDEP has a similar requirement with the TEDE not to exceed 19 mRem/yr plus ALARA. To reach these criteria, derived concentration guideline levels (DCGLs) were developed for radiological exposures from three (3) media components; soil, existing groundwater and future groundwater from left-in place foundations or footings. Based on current conditions, the target dose contribution from existing and future groundwater is not to exceed 2 mRem/yr TEDE. After source (soil) remediationmore » is complete, the NRC requires two (2) years of quarterly monitoring to demonstrate that groundwater quality meets the DCGLs and does not show an upward trend. CYAPCO's NRC License Termination Plan (LTP) specifies a minimum 18-month period of groundwater monitoring, as long as samples are collected during two spring/high water seasons, to verify the efficacy of remedial actions at HNP. In addition to the 19 mRem/yr criteria, the CTDEP also requires groundwater to be in compliance with the Remediation Standards Regulation (RSRs). There are no published criteria for radionuclides in the RSRs, however CTDEP has approved the United States Environmental Protection Agency's (USEPA's) Maximum Contaminant Levels (MCLs) as the clean up standards for individual constituents. After remediation of an identified contamination source, the RSRs require that at least one groundwater monitoring well, hydraulically down-gradient of the remediation area, be sampled to confirm that the remediation has not impacted groundwater quality. After four quarters of groundwater monitoring with results below the MCLs, additional groundwater sampling must continue for up to three years to reach site closure in accordance with the RSRs. The cleanup criteria for chemical constituents, including boron, are regulated by the USEPA under the Resource Conservation and Recovery Act (RCRA) and the CTDEP Bureau of Water Protection and Land Reuse. The USEPA, however, has accepted the CTDEP RSRs as the cleanup criteria for RCRA. Therefore attainment of the CTDEP RSRs is the only set of criteria needed to reach closure, but both agencies retain oversight, interpretation, and closure authority. As stated above, under the RSRs, groundwater must be monitored following a source remediation for a minimum of four quarters. After demonstrating that the remediation was successful, then additional groundwater sampling is required for up to three additional years. However, the number of monitoring wells and frequency of sampling are not defined in the RSRs and must be negotiated with CTDEP. To successfully reach closure, the conceptual site model, groundwater transport mechanisms, and potential receptors must be defined. Once the hydrogeology is understood, a long term groundwater monitoring program can then be coordinated to meet each agencies requirement to both terminate the NRC license and reach site closure under RCRA. (authors)« less
 [1] ;  [2]
  1. MACTEC, Inc., Portland, ME (United States)
  2. Connecticut Yankee Atomic Power Company, East Ham (United States)
Publication Date:
OSTI Identifier:
Report Number(s):
TRN: US10V0053040834
Resource Type:
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
Research Org:
WM Symposia, 1628 E. Southern Avenue, Suite 9 - 332, Tempe, AZ 85282 (United States)
Country of Publication:
United States