RS-14-029, Plan Completion Report for the VB 1 Area
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PLAN COMPLETION REPORT FOR THE VB 1 AREA BRAIDWOOD GENERATION STATION BRACEVILLE, ILLINOIS Prepared For: Exelon Generation Company, LLC DISCLAIMER:
SOME FORMATTING CHANGES MAY HAVE OCCURRED WHEN THE ORIGINAL DOCUMENT WAS PRINTED TO PDF; HOWEVER, THE ORIGINAL CONTENT REMAINS UNCHANGED.
Prepared by: Conestoga-Rovers
& Associates 8615 West Bryn Mawr Chicago, Illinois 60631 OCTOBER 2012 REF. NO. 016841 (44)This report is printed on recycled paper.Office: (773) 380-9933 Fax: (773) 380-6421 web: http:\\www.CRAwortd.com TABLE OF CONTENTS Page
1.0 INTRODUCTION
AND PURPOSE .................................................................................
1
2.0 DESCRIPTION
OF REMEDIATION AREA ...................................................................
3
2.1 DESCRIPTION
OF THE VB 1 AREAS .............................................................
3 2.2 REMEDIAL OBJECTIVES
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3 2.3 PRE-REMEDIATION CONDITIONS
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4 2.4 ACTION PLAN IMPLEMENTATION
-GROUNDWATER PUMPING ...........
4 3.0 CURRENT GROUNDWATER CONDITIONS AT THE VB 1 AREA .........................
5 3.1 CURRENT GROUNDWATER QUALITY CONDITIONS
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5 3.2 CURRENT GROUNDWATER FLOW CONDITIONS
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6 3.3 COMPARISON OF CURRENT GROUNDWATER QUALITY CONDITIONS TO HISTORICAL DATA ..........
6 3.4 EVALUATION OF THE REMEDIAL ACTION ....................................................
6 3.5 EVALUATION OF FUTURE GROUNDWATER CONDITIONS
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7
4.0 CONCLUSION
S
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8 5.0 PLANNED COMPLETION ACTIVITIES
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9
6.0 REFERENCES
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10 016841 (44)CONESTOGA-ROVERS
& ASSOCIATES LIST OF FIGURES (Following Text)FIGURE 2.1 FIGURE 2.2 FIGURE 2.3 FIGURE 2.4 FIGURE 2.5 FIGURE 3.1 FIGURE 3.2 FIGURE 3.3 FIGURE 3.4 FIGURE 3.5 FIGURE 5.1 VB 1 SITE LOCATION MAP LOCATION MAP FOR VB 1 AREA MONITORING WELL LOCATIONS
-VB 1 AREA GROUNDWATER LEVEL CONTOURS -JANUARY 2006 -DEEP GROUNDWATER ZONE ESTIMATED TRITIUM RESULTS -JANUARY 2006 -DEEP GROUNDWATER ZONE TRITIUM CONCENTRATION TRENDS IN MONITORING WELLS AT THE VB 1 AREA GROUNDWATER LEVEL CONTOURS -VB 1 AREA -SEPTEMBER 2011 GROUNDWATER LEVEL CONTOURS -VB 1 AREA -JUNE 11-15, 2012 TRITIUM CONCENTRATIONS
-JUNE 2011 TO JUNE 2012 JANUARY 2006 TRITIUM PLUME VS JUNE 2012 RESIDUAL TRITIUM RGPP MONITORING WELL LOCATIONS IN THE VB 1 AREA LIST OF TABLES
SUMMARY
OF RECENT TRITIUM ANALYSIS NEAR THE VB 1 AREA
SUMMARY
OF CURRENT RGPP MONITORING WELLS IN THE VB 1 AREA
SUMMARY
OF MONITORING WELLS TO BE ABANDONED TABLE 3.1 TABLE 5.1 TABLE 5.2 LIST OF APPENDICES APPENDIX A APPENDIX B
SUMMARY
OF TRITIUM ANALYSES IN MONITORING WELLS NEAR THE VB 1 AREA GROUNDWATER MODELING RESULTS (Memorandum) 016841 (44)CONESTOGA-ROVERS
& ASSOCIATES EXECUTIVE
SUMMARY
This document demonstrates the successful completion of tritium remediation in shallow groundwater at the Exelon Generation Company LLC's (Exelon) Braidwood Generating Station property (Station) in Braceville, Illinois', specifically in the Vacuum Breaker 1 (VB 1) area. Groundwater which had previously been impacted by tritium released from the Station's Blowdown Line has been cleaned up to safe levels through the use of active pumping and monitored natural attenuation.
This Plan Completion Report is submitted in accordance with the requirements of the March 11, 2010 Consent Order and fully describes the program implementation, identifies achievement of the corrective action goals, and demonstrates the efficacy of the remedy as implemented.
In late 2005 and early 2006, surface water and groundwater investigations led to the discovery of elevated tritium concentrations in the groundwater in the VB 1 area. The elevated tritium concentrations in the groundwater were attributed to releases from the vacuum breaker valves. The valves were subsequently repaired, the vaults sealed, and alarms installed to prevent future releases.
In order to remediate the groundwater in the VB 1 area, Exelon initiated active remediation through installation and pumping of three recovery wells (RW-5, RW-6, and RW-7) in October 2006.Through active remediation, tritium concentrations in groundwater in this area have decreased significantly between January 2006 and June 2012. The tritium concentration in July 2006 was 26,793 picocuries per liter (pCi/L) (at monitoring well VB-1-5D), while in June 2012, the concentration in this well was non-detect (below 200 pCi/L). The maximum tritium concentration detected in June 2012 in the area of VB 1 was 917 pCi/L (at monitoring well VB-1-9D).
The active remediation program significantly decreased tritium concentrations in the groundwater to below the drinking water standard and has prevented migration of tritium in groundwater off Exelon-owned property at concentrations greater than the lower limit of detection (LLD) of 200 pCi/L.The information and data contained in this Plan Completion Report for Vacuum VB 1 demonstrates the remedial objectives have been achieved.
More specifically:
The maximum concentrations of tritium in groundwater in the VB 1 area as of June 2012 are less than 2,000 pCi/L, well below the US EPA's drinking water standard;and'The Braidwood Station property includes lands listed under the Station's Nuclear Regulatory Commission (NRC) licensed property along the blowdown line and property purchased by Exelon along Smiley Road and Center Street.016841 (44)i CONEsToGA-ROVERS
& AssociATEs As demonstrated by predictive modeling, the residual levels of tritium in the VB 1 area will not migrate off the Station's licensed property and onto private property at levels above the LLD of 200 pCi/L.016841 (44) ii CONESTOGA-ROVERS
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1.0 INTRODUCTION
AND PURPOSE This Plan Completion Report has been prepared for the Illinois Environmental Protection Agency (IEPA) to address groundwater remediation in the area of Vacuum Breaker 1 at the Braidwood Generating Station property (Station or Site) located in Braceville, Illinois.2 Specifically, this Report discusses the groundwater investigation, monitoring, and remedial actions that were implemented in accordance with the Agreed Preliminary Injunction Order (PIO) dated May 24, 2006, and the March 11, 2010 Agreed Consent Order (ACO), entered into by Exelon and the State of Illinois.
Information collected to date as a result of Action Plan implementation is sufficient to determine that remediation at the VB 1 area is complete and can be concluded.
This report presents sampling data obtained from the Site that demonstrate that the remedial efforts in the VB 1 area have been successful and that all required objectives provided in the Action Plans of the PIO and ACO have been met. All tritium concentrations are currently below 1,000picocuries per liter (pCi/L), and future predictive modeling indicates that tritium will not migrate off the Station's property, even after all pumping activities have stopped. As such, remediation is considered complete for this area.The PIO and ACO were issued in response to several tritium leaks detected by Exelon.In 1996, 2000, and 2005, leaks originating from the vacuum breakers were detected and subsequently repaired.
In the spring of 2005, following the detection of tritium above ambient levels in the perimeter ditch, Exelon investigated shallow groundwater on the east side of the Station, in areas along Smiley Road and Center Street, and along the Station's blowdown line. As a result of these investigations, the vacuum breakers were repaired and active remediation in the VB 1 area was initiated.
In June 2006, the Mitigation Control Plan was prepared to present conceptual remedial alternatives and the selection of a preferred remedial alternative.
As per the Mitigation Control Plan, in August 2006, Exelon installed three recovery wells (RW-5, RW-6, and RW-7)downgradient of VB 1. The recovery wells (RW-5, RW-6, and RW-7) began pumping in October 2006.Since the initiation of these activities, the tritium concentrations in groundwater in the VB 1 area have decreased significantly and active remediation is now complete.
As of June 2012, the highest detected tritium concentration in the area was 917 pCi/L (at VB-1-9D).2 The Braidwood Station property includes lands listed under the Station's Nuclear Regulatory Commission (NRC) licensed property along the blowdown line and property purchased by Exelon along Smiley Road and Center Street.016841 (44)1 CONEsToGA-ROVERS
& AssociATEs As a result of the implementation of the approved Action Plan, the concentrations of tritium detected in groundwater have been reduced to less than 200 pCi/L in the VB 1 area, with the following two exceptions: (a) monitoring well VB-1-9D (917 pCi/L, as of June 2012) and (b) recovery well RW-6 (898 pCi/L, as of June 2012). Additionally, a significant amount of geologic and hydrogeologic data has been collected as part of the Action Plan implementation.
Analyses of these data have revealed the geologic and hydrogeologic characteristics of the subject area, allowing for a better understanding of the groundwater movement and tritium migration.
Predictive modeling indicates that tritium will not migrate further off the Station's property at concentrations greater than the lower limit of detection (LLD) of 200 pCi/L even after all pumping activities have stopped.Documents that provide the foundation for the design and implementation of remedial activities completed at the VB 1 area are presented in Section 7.0 of this Plan Completion Report. Section 7.0 provides a list of references specific to the VB 1 area as well as pertinent documents related to the other areas on the Braidwood Station property where remediation of tritium in groundwater has been performed.
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2.0 DESCRIPTION
OF REMEDIATION AREA This section describes the area being remediated, the remedial objectives required by the IEPA, and Exelon's implementation of the Action Plans to remediate groundwater in the VB 1 area.
2.1 DESCRIPTION
OF THE VB 1 AREA Land surrounding the VB 1 area falls mainly into the agricultural, residential, and recreational use categories (Figure 2.1). The center of the Village of Braidwood is approximately 8,600 feet northeast from VB 1. To the northwest of the Site, there are two main highways (Illinois State Highway 53 and Illinois Route 129) running parallel to each other with a railroad (Southern Pacific Railroad) between them (Figure 2.2).VB 1 is located approximately 500 feet east from the operating areas or "Protected Area" (PA) of the Braidwood Station along the blowdown line. To the south of the VB 1 area is the Cooling Lake. Figure 2.3 presents the monitoring well network in the vicinity of the VB 1 area. This figure includes temporary 1-inch diameter monitoring wells and permanent 2-inch diameter monitoring wells. Since late 2005, a total of 48 monitoring wells have been installed into the deep and shallow zones of the overburden sand aquifer in the VB 1 area.2.2 REMEDIAL OBIECTIVES The intent of the Action Plan was to address the groundwater that may have been impacted by tritium. The first component of the Action Plan was to address the possible migration of tritium off the Exelon owned property.
The second component was to address concentrations of tritium above 200 pCi/L in the VB 1 plume area.The following objectives were established in the Action Plan:* Prevent migration of tritium-impacted groundwater with concentrations in excess of the LLD of 200 pCi/L from migrating off Site;* Remediate the tritium-impacted groundwater on Site;* Remediate the tritium-impacted groundwater on Site to below the LLD of 200 pCi/L; and* Prevent tritium-impacted groundwater from entering the perimeter ditch.016841 (44) 3 CONESTOGA-ROVERS
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& AssoctATEs 2.3 PRE-REMEDIATION CONDITIONS Prior to the initiation of active pumping, a comprehensive groundwater sampling effort was completed in January 2006. Figure 2.4 presents the groundwater elevations and flow directions in the deep overburden sand aquifer for January 2006. This figure indicates that groundwater flows generally northeast to north-northwest in this aquifer in the vicinity of VB 1 under natural (non-pumping) conditions.
Figure 2.5 presents the estimated horizontal distribution of tritium in the vicinity of VB 1 in the deep zones of the overburden aquifer in January 2006. The figure depicts conditions prior to implementation of remedial activity.2.4 ACTION PLAN IMPLEMENTATION
-GROUNDWATER PUMPING To accomplish the Action Plan objectives, as set out in the June 2006 Migration Control Plan, Exelon initiated active remediation, which consisted of pumping water from three recovery wells. The recovered groundwater was discharged into the station's blowdown line and through its NPDES outfall. Three vertical groundwater extraction wells, RW-5, RW-6, and RW-7, were installed in August 2006 (Figure 2.3). Groundwater was extracted from each of the three vertical groundwater extraction wells at a rate of 32 to 35 gallons per minute (gpm). This provided time-sensitive cleanup, controlled groundwater migration, and prevented the off-Site migration of tritium-impacted groundwater as described in the Action Plan.These recovery wells are periodically shut off for manipulations in the circulation water blowdown pumps. In early spring of 2011, RW-7 stopped pumping completely.
RW-6 stopped pumping in late 2011. RW-5 is currently operating.
In accordance with the Action Plan, groundwater monitoring of tritium concentrations and water levels has been performed in the VB 1 area on a quarterly basis. In addition, the capture of groundwater around the recovery wells has also been evaluated quarterly with the use of groundwater contour maps.The data collected during the quarterly sampling events confirm that in the VB 1 area active remediation not only has reduced the tritium in groundwater, but also has prevented the migration of tritium off Site.016841 (~) 4 CONESTOGA-ROVERS
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& AssociATEs 3.0 CURRENT GROUNDWATER CONDITIONS AT THE VB 1 AREA This section presents the current groundwater conditions, an evaluation of the remedial action, and an evaluation of future groundwater conditions at the VB 1 area.3.1 CURRENT GROUNDWATER QUALITY CONDITIONS The concentrations of tritium in groundwater in the VB 1 area have been significantly reduced since active remediation was initiated.
The most recent groundwater sampling event at each monitoring well location, as presented in Table 3.1, confirmed there are no instances of tritium in groundwater at concentrations above or approaching US EPA's drinking water standard of 20,000 pCi/L. The concentrations of tritium measured in groundwater have been reduced by as much as 100% at some well locations (e.g., MW-109D, MW-131D, RW-7, and VB-I-1). Currently, no groundwater samples collected near VB 1 have tritium concentrations above 1,000 pCi/L.One of the tools used to evaluate groundwater conditions included a statistical analysis of each monitoring well that was sampled between January 2006 and June 2012.Appendix A presents the analytical results. In some cases, data was available prior to January 2006, in which case, the earlier data was also utilized.
Statistical analyses 3 include the trend, percent reduction, and minimum and maximum concentrations for each monitoring well. Statistical analyses were only performed utilizing data from monitoring locations with tritium concentrations greater than the LLD during at least one sampling event between January 2006 and June 2012. This included 15 sampling locations.
Monitoring wells without tritium concentrations greater than the LLD for at least one sampling event between January 2006 and June 2012 were excluded from the statistical analysis.Table 3.1 presents the most recent tritium concentrations detected in monitoring wells in the VB 1 area between October 2010 and June 2012. The statistical analyses demonstrate a predominately downward trend of tritium concentrations in the groundwater in the vicinity of VB 1. Figure 3.1 presents this predominately downward trend in tritium concentrations over time at select monitoring wells in the VB 1 area.In October 2010, groundwater samples obtained from monitoring well VB-1-9D showed that tritium concentrations decreased to below 200 pCi/L. However, the following six sampling events indicate that the concentrations returned to levels similar to those prior 3 The trend was determined from the Mann-Kendall Trend Test. Percent reduction was calculated from the highest detected concentration and the most current concentration.
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& AssociATEs to October 2010. This sudden change is believed to have been influenced by the temporary inoperability of the recovery wells. While the recovery wells were shut off, the tritium appears to have migrated slightly downgradient, but once the recovery wells were returned to service the tritium was pulled back to VB-1-9D by the pumping.3.2 CURRENT GROUNDWATER FLOW CONDITIONS Figure 3.2 presents the September 2011 groundwater level contours while recovery wells RW-5 and RW-6 were pumping. Water levels have not been recorded at RW-5 and RW-6 since March 2010; as such, these water levels were utilized in the September 2011 contours.
Since the shallow and deep monitoring wells are located within the same hydraulic unit and have historically indicated similar groundwater elevations, the shallow and deep monitoring well elevations are contoured together.
Groundwater flow is generally to the north. This figure also indicates the capture of groundwater around RW-5, which was being pumped in September 2011.Figure 3.3 presents the June 2012 groundwater level contours while recovery wells RW-5, RW-6, and RW-7 were not pumping. The data from these measurements indicate that groundwater flow was to the northeast.
3.3 COMPARISON OF CURRENT GROUNDWATER QUALITY CONDITIONS TO HISTORICAL DATA Figure 3.4 presents the tritium concentrations in the groundwater for samples collected between June 2011 and June 2012, utilizing the latest available data for each monitoring well. These samples were collected both from the permanent monitoring wells and from temporary piezometers and monitoring wells located in the VB 1 area.Figure 3.5 presents a comparison of the January 2006 tritium plume versus the June 2012 residual tritium in the VB 1 area. The data and supporting figure indicate a significant decrease in tritium concentrations since remedial activities began in October 2006.Tritium concentrations have been reduced from over 22,928 pCi/L to less than 1,000 pCi/L.3.4 EVALUATION OF THE REMEDIAL ACTION The remedial activities performed in the VB 1 area over the last 6 years have been very successful in decreasing the concentrations and reducing the extent of tritium in 01681 (44)6 CONESTOGA-ROVERS
& AssociATEs groundwater.
During the course of pumping activities at RW-5, RW-6, and RW-7, groundwater has been monitored on a quarterly basis for tritium concentrations and groundwater levels. The data collected from these wells are presented in Appendix A and on Figures 3.1 through 3.5. These data provide sufficient information to demonstrate: " There is no groundwater in this area that is above or approaching the drinking water standard of 20,000 pCi/L;" The limits of detectable tritium (above the LLD of 200 pCi/L) in this area have not extended beyond the Braidwood Station licensed property boundary;" Only two out of 18 monitoring wells sampled during the comprehensive sampling event in June 2012 indicated tritium above the LLD of 200 pCi/L;* Since June 2006, the cone of influence (capture zone) of the three recovery wells used for remediation has been successful in preventing the further migration of tritium in groundwater in this area; and" The cone of influence and the capture zone of the three recovery wells used for remediation have been successful in the overall reduction of tritium in groundwater in this area from concentrations detected in June 2006 to those detected in June 2012.3.5 EVALUATION OF FUTURE GROUNDWATER CONDIONS Predictive modeling simulations were performed in 2012 in order to determine the effect of a complete shutdown of all pumping activities (RW-5, RW-6, and RW-7) in the VB 1 area on tritium extent and concentrations.
The primary objective of this modeling effort was to evaluate how long it will take for the areas of residual tritium to dissipate (i.e., with tritium concentrations reduced to below the LLD of 200 pCi/L). The second objective of the modeling was to determine the migration pathway of the residual tritium. The memorandum presenting this groundwater flow and transport modeling effort is provided in Appendix B.The modeling results demonstrate that the extent of the residual tritium area will decrease while the area may migrate slightly further downgradient from the current location; however, it will dissipate within the Exelon property line. The area of residual tritium will eventually reduce to below the LLD of 200 pCi/L less than 1.6 years (570 days) after the pumping cessation.
In addition, tritium concentrations in certain wells are expected to increase initially as the plume begins to migrate and then drop sharply to below the LLD (200 pCi/L) as natural attenuation occurs.016841 (44) 7 CONESTOGA-ROVERS
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4.0 CONCLUSION
S The remedial activities in the VB 1 area have resulted in a significant decrease in tritium concentrations and reduction in the overall extent of tritium in groundwater.
This reduction has occurred in the last 6 years through active pumping and through natural attenuation of tritium in the groundwater.
This Plan Completion Report documents the effectiveness of the remedial activities to date, as well as the ability of natural attenuation to eliminate the remaining isolated area of residual tritium. Specifically, the following conclusions have been reached with regard to the remedial actions at the VB 1 area: " Concentrations of tritium in groundwater are less than the drinking water standard of 20,000 pCi/L.* As of June 2012, tritium concentrations in groundwater have decreased to less than 1,000 pCi/L.* The area of residual concentrations of tritium above 200 pCi/L will not migrate off Exelon property and will not impact off-Site private groundwater users.016841 (44)8 CONESTOGA-ROVERS
& ASSOCIATES 5.0 PLANNED COMPLETION ACTIVITIES As a final component of the remedial strategy at the VB 1 area, the groundwater pumping activities will be shut down. In addition, the current quarterly groundwater monitoring program will be discontinued.
However, as part of the nuclear power industry's voluntary groundwater monitoring programs, Exelon will continue groundwater monitoring of a number of key monitoring wells in the VB 1 area. The monitoring wells that were associated with the quarterly groundwater monitoring program will be abandoned.
Each of these aspects is presented in more detail below.Shutdown of Pumping Activities Exelon will terminate the pumping of recovery wells (RW-5, RW-6, and RW-7) and dismantle the equipment.
Upon shutdown of the pumping systems, the groundwater level is expected to recover upward to conditions prior to pumping. (i.e., similar to the surrounding static groundwater elevations).
It is anticipated that Exelon will restore the land surface and vegetation in the areas of the pumping equipment and discharge lines to at least the same conditions as prior to remedial activities.
Groundwater Monitoring Program While the current monitoring program will be discontinued, the VB 1 area will continue to be monitored through Exelon's Radioactive Groundwater Protection Program (RGPP)4.The RGPP is a program that meets the guidance provided by NEI 07-07, ANI 07-01, and EPRI 1015118. VB 1 area monitoring wells included in the RGPP are presented in Table 5.1 and on Figure 5.1. The goal of the RGPP monitoring is to ensure that any potential future impacts to groundwater are identified by Exelon in a timely manner.Monitoring Well Abandonment Monitoring wells in the VB 1 area that are not associated with the RGPP will be abandoned and sealed. The monitoring wells to be abandoned and sealed are listed in Table 5.2. Monitoring wells designated BL are considered blowdown line monitoring well locations and will not be abandoned.
4 Monitoring wells that are currently above 200 pCi/L, but not included in the RGPP, will be monitored during RGPP sampling events. These monitoring wells will continue to be monitored until two consecutive sampling events indicate tritium concentrations below 200 pCi/L, at which time the monitoring well will be abandoned.
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6.0 REFERENCES
CRA, March 2006. Tritium Investigation, Exelon Generation, Braidwood Station, Braceville, Illinois.CRA, May 2006. Agreed Preliminary Injunction Order.CRA, June 2006. Migration Control Plan Vacuum Breaker 1, Braidwood Generation Station, Braceville, Illinois.http: / / myportalapps
/ reporttitle/
reportentry.aspx?action=edit&projectNum=16 841&reportlD=43136 CRA, August 2006. Groundwater Flow and Tritium Transport Modeling, Braidwood Generating Station, Braceville, Illinois.CRA, September 2006. Hydrogeologic Investigation Report, Fleetwide Assessment, Braidwood Generating Station.CRA, November 2006. Hydraulic Monitoring for the Will County Forest Preserve Work Plan Braidwood Generating Station Braceville, Illinois.CRA, December 2006. CRA Memorandum, Transient Groundwater Flow Model Calibration and Transport Model Scenario Update.CRA, January 2007. Wedron Clay Till Investigation Report Braidwood Generating Station, Braceville, Illinois.Harbaugh, A.W., Banta, E.R., Hill, M.C., and McDonald, M.G., 2000. MODFLOW-2000, The U. S. Geological Survey Modular Ground-Water Model -User Guide to Modularization Concepts and the Ground-Water Flow Process, United States Geological Survey Open-File Report 00-92, Reston, Virginia.Harbaugh, A.W. and M.G. McDonald, 1996a. User's Documentation for MODFLOW-96, an update to the U.S. Geological Survey Modular Finite-Difference Ground-Water Flow Model, United States Geological Survey Open-File Report 96-485, Reston, Virginia.Harbaugh, A.W. and M.G. McDonald, 1996b. User's Documentation for MODFLOW-96, an update to the U.S. Geological Survey Modular Finite-Difference Ground-Water Flow Model, United States Geological Survey Open-File Report 96-486, Reston, Virginia.McDonald, M.G. and A.W. Harbaugh, 1988. A Modular Three-Dimensional Finite-Difference Ground-Water Flow Model, United States Geological Survey Open-File Report 83-875.Pollock, D.W., 1994. User's Guide for MODPATH/MODPATH-PLOT, Version 3: A particle tracking post-processing package for MODFLOW, the U.S. Geological 016841 (44)10 CONESTOGA-ROVERS
& AssocLATEs Survey finite-difference ground-water flow model: U.S. Geological Survey Open-File Report 94-464.Sargent and Lundy, 1988. Updated Final Safety Analysis Report (UFSAR) Revision 1.0, December 1994. Chapters 2.4 and 2.5.Zheng, C., and P. Wang, 1999. MT3DMS: MT3DMS: A Modular Three-Dimensional Multispecies Transport Model for Simulation of Advection, Dispersion, and Chemical Reactions of Contaminants in Groundwater Systems; Documentation and User's Guide. Prepared by University of Alabama, Prepared for US Army Corps of Engineers.
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& AssocIATES 4.0 400 a0ocO~74 LEGEND VS-1 A VACUUM BREAKER LOCATION AND WEIIVER-- BLOW DWN UE L t figure 2.1 VB 1 SITE LOCATION MAP EXELON GENERATION BRAIDWOOD STATION Baceville, linois
St M LEGEND.EXISTING FENCE MNE-SLOWDOWN UNE APPROXIATE PROPERTY BOUNDARY 13-1 & VACUUM BREAKER LOCATION AND IDENTIFIER
..01 M SLOWDOWN LINE SAM NG LOCATION AND IDENTIFER W-109o SHALLOW MONITORING WELL LOCATION AND IDENTIRER.- DEEP MONITORING WELL LOCATION AND IDENTIFIER 0-2 0 SHALLOW TEMPORARY WELL LOCATION AND UENT9IFIER 0-200 DEEP TEMPORARY WELL LOCATION AND IDENTIFIER VS-1-2 *vs-I-2 0*RW-SEM SHALLOW VACUUM BREAKER SAMPLING LOCATION AND IDENTIFIER DEEP VACUUM BREAKER SAMPLING LOCATION AND IDENTIFIER RECOVERY WELL LOCATION AND IDENTIFIER EXELON POND VB10 0 200 400R figure 2.3 MONITORING WELL LOCATIONS
-VB 1 AREA GROUNDWATER MONITORING PROGRAM EXELON GENERATION BRAIDWOOD STATION Bracevilie, Illinois
100O0 10000 C 0100 loo 10-'0-MW-131D
--RW-5-4-RW-7 p1.'m-200 p0UL LLD-LOWER LIMIT OF DETECTION figure 3.1 TRITIUM CONCENTRATION TRENDS IN MONITORING WELLS AT THE VB 1 AREA EXELON GENERATION BRAIDWOOD STATION Braceville, Illinois 16841-74(044)GN-C0006 OCT 08/2012 0 0 a
-i LZJ-J MW-111 (589."3)s/I VB-I.S (590 83)0 0 75 1501t LEGEW.S- APPROXIMATE PROPERTY BOUNDARY-583- GROUNDWATER CONTOURS--x EXISTING FENCE UNE S LOWDOWNULNE
~Z2~2~>GROUNDWATER FLOW DIRECTION VB-I & VACUUM BREAKER LOCATION AND IDENTIFER VBI-5-D 4 DEEP VACUUM BREAKER SAMPLE LOCATION AND IDENTIFIER VB-I-5 0 SHALLOW VACUUM BREAKER SAMPLE LOCATION AND IDENTIFIER V .. !31 t0 DEEP MONITORING WELL LOCATION AND IDENTIFIER MW-111 0 SHALLOW MONITORING WELL LOCATION AND IDENTIFIER I-2D 0 DEEP TEMPORARY MONITORING WELL LOCATION AND IDENTIFIER D-2 0 SHALLOW TEMPORARY MONITORING WELL LOCATION AND IDENTIFIER RW S M RECOVERY WELL LOCATION AND IDENTIFIER (591.22) GROUNDWATER ELEVATIONS NOTES: RW-5 AND RW-6 GROUNDWATER ELEVATIONS WERE RECORDED ON MARCH S. 2010. THIS WAS THE LAST TIME WATER LEVEL MEASUREMENTS WERE TAKEN AT RW-S AND RW-S RW-7 WAS NOT PUMPING DURING TIE SEPTEMBER 2011 MONITORING EVENT.SHALLOW AND DEEP MONTORING WELLS ARE SCREENED WITHIN THE SAME SANDSTONE UNIT AND HAVE HISTORICALLY HAD SIMILAR WATER LEVELS, THEREFORE, THESE WELLS HAVE BEEN CONTOURED TOGETHER.figure 3.2 GROUNDWATER LEVEL CONTOURS -VB 1 AREA SEPTEMBER 2011 EXELON GENERATION BRAIDWOOD STATION BraceIlle, Ilinois VB-1-7*(591.04)VB-1.-1D (591.10).30)D-2 (591.22)-mmm ------
VB-1-12D (5s0on &0-1 MW-111.T6 0 100 2000 VB.-1-7 (V5-1-0D (s01-00)LEGEW.EXISTING FENCE LINE S -SLOWDOWN LINE 13- GROUNDWATER CONTOUR ELEVATION> GROUNDWATER FLOW DIRECTION BL-01 0 SHALLOW SLOWDOWN LINE SAMPLING LOCATION AND IDENTIFIER VB-1 A VACUUM BREAIKER LOCATION AND IDNTIFIER VS-i-iD I DEEP VACUUM BREAKER SAMPLE LOCATION AND IDENTIFIER VS-I-1 0 SHALLOW VACUUM REAKER SAMPLE LOCATION AND IDENTIFIER MW-1A0b 0 DEEP MONITORING WELL LOCATION AND IDENTIFIER MW-101 S SHALLOW MONITORING WELL LOCATION AND IDENTIFIER D-10 0 DEEP TEMPORARY MONITORING WELL LOCATION AND IDENTIFIER oD.4 D-2 oD-5)BL-050 BL.-03---- -_____ (591,47)C BL-04 0-0-1 0 SHALLOW TEMPORARY MONITORING WELL LOCATION AND IDENTIFIER R.W-' M RECOVERY WELL LOCATION AND IDENTIFIER SG-I A STAFF GAUGE LOCAT1ON AND IDENTIFIER VI..-.-NOTE: RW-5. 6 AND 7 WERE NOT PUMPING figure 3.3 GROUNDWATER CONTOURS -VB I AREA JUNE 11-15 2012 EXELON GENERATION BRAIDWOOD STATION Bra"vlle, Ilinais
0 150 3001t--L K!r*1/(4W)0)* D-m//\ (* 4W)-_____ -~- -::--z -: : ----ZNS 2 i Wei A SLOWDOWN LINE PLANT PROPERLY UNE DEEP BLOWDOWN UNE SAMP.ING LOCATION VACUUM BREAKER LOCATION wa-t-no DEEP VACUUM BREAKER SAMPLING MW-ifý DEEP MONITORING WELL LOCATION D-1 0 a DEEP TEMPORARY WELL LOCATION D,484) TRITIUM RESULT IN GROUNDWATER
-200-- TRET~tm CONTOIM BAOCKGOUND TRITIUM CONCENTRATION:
200 pCYL DRIUNING WATER STANDAR FCR TRII 2%=O PCV TRITIUMA DATA FOR SAMPLES COLLECTED TIýC JANUARY 3k2M. SSONTCURI WERtE GENERATED SUSING LDGVAUS LOCATION-TRmIUM RESULTS 200.000 TO 250,000 PICOCURIES/Ln'ER (pW.)-TRITIUM RESULTS 100,000 G0 200K000-TRITIUM RESULTS 80.00D TO 100,000 TRITIUM RESULTS 40,000 TO 80,000-TRITIUM RESULTS 20,000 TO 40,000 m TRITIUM RESULTS 1000 To 20,000 TRITIUM RESULTS 5.000 TO 10.000 TRITIUM RESULTS 200 TO 5.000 TRITIUM RESULTS 0 TO 200 (ND) NONDETECT BELOW 200 PCYL APPROXIMATE PROPERTY BOUNDARY--, SLOWDOWN LINE VS-1 A VACUUM BREAKER LOCATION AND IDENTIFiER VB-I,81D 0 DEEP VACUUM BREAKER SAMPLE LOCATION AND IIFIE VS-I-I & SHALLOW VACUUM BREAKER SAMPLE LOCATION AND IDENTIFER MW-5 1 EOD IS DEEP MONITORING WELL LOCATION AND IDENTIFIER 0-20) 0 DEEP TEMPORARY MONITORING WELL LOCATION AND IDENTIFIER RW-5 M RECOVERY WELL LOCATION AND IDENTIFIER-TRITIUM RESULTS 5,000 TO 1,000 PICOCURESJUTER WCA)TRITIUM RESULTS 200 TO 1,000 TRITIUM RESULTS 0 TO 200 (*LLD) LESS THAN THE LOWER LIMIT OF DETECTION OF 200 pCV.NOTES:" I- ALL TRITIUM RESULTS ARE IN PICOCURIES PER LITER (pOrL)2- THE MOST RECENT AVAILABLE DATA BETWEEN2011 AND JUNE 2012 FOR EACH MONITORING WELL LOCATION IS PRESENTED inU&AJM UMNA. &A4 1I9UJMA WHXJAT9d IIguru 0.o JANUARY 2006 TRITIUM PLUME VS JUNE 2012 RESIDUAL TRITIUM EXELON GENERATION BRAIDWOOD STATION BracevIlle, Illinois 11SH1-74(044)GN-CO010 OCT 08=212 EXISTING FENCE LINE BLOWOOWN LINE BL-03 M MW-lUG @mw-lID RW-6 M APPROXIMATE PROPERTY BOUNDARY BLOWOOWN LINE SALPLING LOCATION DEEP MONITORING WELL LOCATION SHNALOW MONIORING WELL LOCATION RECOVERY WELL LOCATION EXELON POND C 0 200 400ft-fR'4..ligu 0. 1 RGPP MONITORING WELL LOCATIONS IN THE VB 1 AREA EXELON GENERATION BRAIDWOOD STATION Bracevile, Illinois TABLE 3.1 Page 1 of 1
SUMMARY
OF RECENT TRITIUM ANALYSIS NEAR THE VB 1 AREA EXELON GENERATION BRAIDWOOD STATION BRACEVILLE, ILLINOIS Sample R Location Date 1 esult 2 ,Ci/L)Sample]D-1D D-2D D-3D MW-109D MW-110 MW-111DR MW-130D MW-131D RW-5 RW-6 RW-7 VB-1-1 VB-I-ID VB-1-2D VB-1-3D VB-1-4D VB-1-5D VB-1-6D VB-1-7D VB-1-8D VB-1-9 VB-1-9D VB-1-10D VB-1-11D VB-1-12D 6/12/2012 6/12/2012 6/12/2012 6/11/2012 12/15/2011 6/13/2012 6/11/2012 6/13/2012 7/13/2011 6/11/2012 6/13/2012 6/18/2012 4/21/2011 6/18/2012 6/18/2012 6/12/2012 6/12/2012 6/13/2012 6/13/2012 6/13/2012 2/16/2012 6/11/2012 12/27/2010 12/18/2010 6/13/2012 ND ND ND ND ND ND ND ND ND 898 ND ND ND ND ND ND ND ND ND ND ND 917 ND ND ND 1 The sample date presented is the latest available data for the indicated monitoring well.2 Non-detect (ND) below 200 pCi/L.CRA 016841 (44)
Page 1 of 1 TABLE 5.1
SUMMARY
OF CURRENT RGPP MONITORING WELLS IN THE VB 1 AREA 0EXELON GENERATION BRAIDWOOD STATION BRACEVILLE, ILLINOIS RGPP Monitoring Wells "2 BL-03 MW-109D MW-110 MW-111DR MW-130D MW-131D RW-5 RW-6 RW-7 VB-I-1'RGPP -Radiological Groundwater Protection Program RvGPP surface water sample locations and monitoring well locations outside the W VB 1 area are not included in this table.CRA 016841 (44)
Page 1 of 1 TABLE 5.2
SUMMARY
OF MONITORING WELLS TO BE ABANDONED EXELON GENERATION BRAIDWOOD STATION BRACEVILLE, ILLINOIS D-1 D-1D D-2 D-2D D-3 D-3D D-4 D-5 MW-107 MW-108 MW-109 MW-111 MW-132D VB-I-ID VB-1-2 VB-1-2D VB-1-3 VB-1-3D VB-14 VB-14D VB-1-5 VB-1-5D VB-1-6 VB-1-6D VB-1-7 VB-1-7D VB-1-8 VB-1-8D VB-1-9 VB-I-10 VB-I-10D VB-1-11 VB-1-11D VB-1-12D CRA 016841 (44)
APPENDIX A
SUMMARY
OF TRITIUM ANALYSES IN MONITORING WELLS NEAR THE VB 1 AREA 016841(44)
APPENDIX A Page 1 of 2
SUMMARY
OF TRITIUM ANALYSIS IN MONITORING WELLS NEAR THE VIi AREA Sample Location' Sample Date Result 2 Sample Location' Sample Date Result'Sample Location' Sample Date Result 2 Sample Location' Sample Date Result 2 Sample Location' Sample Date Result 2 I 1 1 4 D-3D 12/23/2005 4674 D-3D 1/4/2006 5110 D-3D 9/18/2007 1829 D-3D 9/15/2008 ND D-3D 10/13/2009 635 D-3D 6/10/2010 ND D-3D 9/27/2010 ND D-3D 12/21/2010 ND D1)3D 6/23/2011 ND D-3D 6/12/2012 ND MW-109D 9/12/2006 467 MW-109D 11/6/2006 686 MW-109D 3/12/2007 257 MW-109D 7/26/2007 906 MW-109D 9/14/2007 516 MW-109D 12/12/2007 ND MW-109D 3/7/2008 ND MW-109D 5/9/2008 ND MW-109D 9/22/2008 ND MW-109D 12/16/2008 ND MW-109D 3/11/2009 ND MW-109D 10/16/2009 ND MW-109D 12/9/2009 ND MW-109D 9/30/2010 ND MW-109D 10/2/2010 ND MW-109D 12/29/2010 ND MW-109D 3/28/2011 ND MW-109D 6/27/2011 ND MW-109D 11/16/2011 ND MW-109D 6/11/2012 ND MW-130D 9/12/2006 1885 MW-130D 11/6/2006 1727 MW-130D 3/12/2007 ND MW-130D 6/21/2007 526 MW-130D 9/14/2007 ND MW-130D 12/12/2007 423 MW-130D 3/7/2008 ND MW-130D 5/9/2008 ND MW-130D 9/22/2008 ND MW-130D 9/22/2008 ND MW-130D 12/16/2008 ND MW-130D 3/11/2009 ND MW-130D 10/16/2009 ND MW-130D 12/9/2009 ND MW-130D 9/29/2010 ND MW-130D 12/29/2010 ND MW-130D 3/28/2011 ND MW-130D 11/16/2011 ND MW-130D 6/11/2012 ND MW-131D 9/12/2006 7770 MW-131D 11/6/2006 234 MW-131D 3/12/2007 413 MW-131D 6/11/2007 ND MW-131D 9/11/2007 ND MW-131D 12/12/2007 ND MW-131D 3/12/2008 ND MW-131D 6/11/2008 ND MW-131D 9/17/2008 ND MW-131D 12/18/2008 ND MW-131D 3/10/2009 ND MW-131D 6/10/2009 ND MW-131D 9/16/2009 ND MW-131D 12/10/2009 ND MW-131D 3/9/2010 ND MW-131D 6/10/2010 ND MW-131D 9/28/2010 ND MW-131D 12/14/2010 ND MW-131D 3/14/2011 ND MW-131D 6/20/2011 ND MW-131D 9/22/2011 ND MW-131D 11/15/2011 ND MW-131D 6/13/2012 ND RW-5 8/16/2006 1113 RW-5 10/2/2006 756 RW-5 10/11/2006 1797 RW-5 9/14/2007 1313 RW-5 3/19/2008 1050 RW-5 6/27/2008 869 RW-5 RW-5 RW-5 RW-5 RW-5 3/31/2009 1219/2009 4/21/2M1 7/13/2011 7/13/2011 RW-6 8/23/2006 3826 RW-6 10/2/2006 3545 RW-6 10/11/2006 4817 RW-6 9/14/2007 4437 RW-6 2/29/2008 3270 RW-6 6/27/2008 2750 RW-6 3/31/2009 1640 RW-6 10/16/2009 387 RW-6 12/9/2009 298 RW-6 4/21/2011 754 RW-6 6/27/2011 587 RW-6 7/13/2011 441 RW-6 6/11/2012 898 RW-7 8/23/2006 7729 RW-7 10/2/2006 11316 RW-7 10/11/2006 10608 RW-7 9/14/2007 526 RW-7 3/19/2008 216 RW-7 6/27/2008 ND RW-7 9/15/2008 ND RW-7 3/31/2009 ND RW-7 10/13/2009 ND RW-7 6/10/2010 ND RW-7 9/27/2010 ND RW-7 12/14/2010 ND RW-7 4/21/2011 ND RW-7 6/23/2011 ND RW-7 6/13/2012 ND 400 391 ND ND ND VB-1-i 9/12/2006 ND VB-i-1 10/11/2006 ND VB-i-1 11/6/2006 ND VB-i-1 12/11/2006 ND VS-1-i 1/9/2007 ND VB-i-1 2/15/2007 ND VB-I-1 3/14/2007 ND VB-I-1 4/12/2007 ND VB-I-1 5/14/2007 ND Va1-1 6/21/2007 ND VS-1-1 7/27/2007 ND VB-i-1 8/15/2007 ND VB-i-1 9/14/2007 ND VS-1-1 10/9/2007 ND VS1-1 11/21/2007 ND VS-i-1 12/12/2007 ND VB-i-1 1/16/2008 ND VB-I-1 2/13/2008 ND VS-1-1 3/7/2008 ND VS-1-i 4/2/2008 ND VB-i-1 5/9/2008 ND VB-I-1 6/11/2008 ND VB-i-1 7/17/2008 ND VS-1-1 8/12/2008 ND VS-1-1 10/26/2008 ND VB-i-1 11/12/2008 ND VB-I-1 12/16/2008 ND VB-1-1 1/14/2009 ND VS1-1 2/12/2009 ND VB-i-1 3/13/2009 ND VB--I1 4/14/2009 ND VS-1-1 8/10/2009 ND VS-1-1 10/11/2009 ND VB-I-1 12/8/2W09 ND VB-i-1 1/12/2010 ND VB-i-1 2/9/2010 ND VB-i-1 4/20/2010 ND VB--I1 6/8/2010 ND VB-i-1 7/17/2010 ND VB-i-1 9/28/2010 ND VS-1 12/18/2010 ND VB-i-1 1/18/2011 ND VB-i-1 1/18/2011 ND VB-i-1 3/16/2011 ND VB-i-1 4/21/2011 ND VB-I-1 12/13/2011 ND VB-I-1 6/18/2012 ND VB-1-2 11/17/2005 337 VB-1-2 7/24/2006 ND VB-1-2 9/25/2007 ND VS-i-3D 1/13/2006 19431 VB-1-3D 7/24/2006 14912 VB-1-3D 9/26/2007 4018 VB-1-3D 10/18/20O8 450 VB-I-3D 10/21/2009 ND VB-i-3D 9/28/2010 ND VB-1-3D 12/18/2010 ND VB-i-3D 6/18/2012 ND VB-1-4 11/15/2005 384 VB-14 7/24/2006 ND VB-1-4D 1/13/2006 7424 VS-1.4D 7/24/2006 3429 VB-1-4D 9/18/2007 416 V-I-4D 9/26/2007 310 VB-14D 10/19/2008 ND VB-14D 10/16/2009 ND VB-1-4D 9/29/2010 ND VB-14D 12/27/2010 ND VB-1-4D 6/12/2012 ND VB-1-SD 1/13/2006 22928 VS-i-SD 5/22/2006 24808 VB-i-SD 7/24/2006 26973 VB-1-5D 9/24/2007 1282 VS-I-5D 1/17/2008 1000 VB-i-SD 10/19/2008 647 VB-1-SD 10/16/2009 ND VB-1-SD 9/29/2010 ND VB-i-5D 12/27/2010 ND VS-i-SD 6/12/2012 ND VB-I-1 VB-l-1 VB-1-1 VB-1-1 VB-I-1 11/15/2005 1/4/2006 7/10/2006 7/24/2006 8/14/2006 1194 425 248 ND 210 CRA 1 IM q44 0 APPENDIX A
SUMMARY
OF TRITIUM ANALYSIS IN MONITORING WELLS NEAR THE VB 1 AREA Page 2 of 2 Sample Location' Sample Date Result 2 Sample Location' Sample Date Result 2 Sample Location' Sample Date Result 2 Sample Location' Sample Date Result 2 Sample Location' Sample Date Result2 I I q.VB-1-SD 1/9/2006 10877 VB-1-SD 7/25/2006 24458 VB-1-8D 9/14/2007 ND VB-1-8D 1/16/2008 ND VB-1-8D 10/13/2009 ND VB-1-ID 6/10/2010 ND VB-1-8D 9/30/2010 ND VB-1-8D 12/14/2010 ND VB-I-SD 6/20/2011 ND VB-1-ID 6/13/2012 ND VB-1-9D 1/13/2006 3370 VB-1-90 5/22/2006 2866 VB-1-9D 7/24/2006 2437 VB-1-9D 9/13/2007 6744 VB-1-9D 9/24/2007 7401 VB-1-9D 10/9/2007 7260 VB-1-9D 3/12/2008 8800 VB-1-9D 5/9/2008 5500 VB-1-9D 9/17/2008 5230 VB-1-9D 12/16/2008 3230 VB-1-9D 3/11/2009 1870 VB-1-9D 10/21/2009 1740 VB-1-9D 8/24/2010 1670 VB-1-9D 9/30/2010 1430 VB-1-9D 10/2/2010 ND VB-1-9D 12/29/2010 1060 VB-1-9D 3/17/2011 1290 VB-1-9D 3/28/2011 1640 VB-1-90 6/24/2011 3680 VB-1-90 2/16/2012 1670 VB-1-9D 6/11/2012 917 Notes: Non-Impacted Well D-1D 12/23/2005 ND D-1D 1/4/2006 ND D0-D 9/26/20o7 ND D-1D 10/19/2008 ND D-1D 10/16/2009 ND D-iD 9/29/2010 ND D-1D 12/14/2010 ND D-1D 6/12/2012 ND D-2D 12/23/2005 D-2D 1/4/2006 ND D-2D 10/13/2009 ND D-2D 6/10/2010 ND D-2D 9/27/2010 ND D-2D 12/14/2010 ND D-2D 6/23/2011 ND D-2D 6/12/2012 ND MW-110 10/20/2005 ND MW-110 11/15/2005 ND MW-l0 1/4/2006 ND MW-110 6/13/2007 ND MW-110 9/11/2007 ND MW-110 12/12/2007 ND MW-110 3/13/2008 ND MW-110 6/11/2008 ND MW-10 9/17/2008 ND MW-110 12/18/2008 ND MW-110 3/10/2009 ND MW-110 6/10/2009 ND MW-110 6/10/2009 ND MW-110 9/16/2009 ND MW-110 12/8/2009 ND MW-110 3/10/2010 ND MW-110 6/9/2010 ND MW-110 9/30/2010 ND MW-110 12/15/2010 MW-110 3/15/2011 MW-110 6/23/2011 MW-110 9/22/2011 MW-110 12/15/2011 ND ND ND ND ND MW-111DR 9/12/2006 MW-111DR 11/6/2006 MW-111DR 3/12/2007 MW-111DR 6/11/2007 MW-111DR 9/11/2007 MW-111DR 12/12/2007 MW-111DR 3/12/2008 MW-111DR 6/11/2008 MW-111DR 9/17/2008 MW-111DR 12/18/2008 MW-111DR 3/10/2009 MW-111DR 6/10/2009 MW-111DR 6/10/2009 MW-111DR 9/16/2009 MW-11DR 12/10/2009 MW-111DR 3/9/2010 MW-111DR 6/10/2010 MW-111DR 9/28/2010 MW-i1DR 12/15/2010 MW-111DR 3/14/2011 MW-111DR 6/20/2011 MW-111DR 9/22/2011 MW-111DR 12/15/2011 MW-111DR 6/13/2012 ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND VB-1-2D 1/13/2006 238 VB-1-2D 7/24/2006 252'1-I-2D 9/25/2007 ND VB-1-2D 10/18/2008 ND VB-1-2D 10/21/2009 ND VB-1-2D 10/2/2010 ND VB-1-2D 6/18/2012 ND VB-1-3 11/15/2005 206 VB-1-3 7/24/2006 ND VB'-1-5 11/15/2005 ND VB-1-5 7/24/2006 ND VB-1-5 9/24/2007 ND w1-1-6 11/22/2005 ND VB-1-6 6/23/2006 ND VB-1-6 7/25/2006 ND VB-1-6D 1/13/2006 ND VB-1-6D 6/28/2006 ND VB-1-6D 7/25/2006 ND VB-1-6D 10/13/2009 ND VB-1-6D 6/10/2010 ND VB-1-6D 9/27/2010 ND VB-1-6D 12/14/2010 ND VB'-1-60 6/20/2011 ND VB-1-60 6/13/2012 ND VB-1-7 11/22/2005 ND'1-1-7 7/25/2008 ND'1-I-7D 1/9/2006 ND'1-1-7D 7/25/2006 ND VB-1-7D 9/14/2007 ND VB-1-7D 9/15/2008 ND VB-1-7D 10/13/2009 ND VB-1-7D 6/10/2010 ND VB-1-7D 9/27/2010 ND VB-1-7D 12/14/2010 ND VB-1-7D 6/20/2011 ND VB-1-7D 6/13/2012 ND V1-1-8 11/22/2005 ND VB-1-8 7/25/2006 ND VB-1-9 11/22/2005 ND VB-1-9 7/24/2006 ND VB-1-9 2/16/2012 ND'1-1-10D 9/26/2007 ND VB-1-10D 10/18/2008 ND'1-1-100 10/21/2009 ND VB-1-10D 9/28/2010 ND VB-1-10D 12/27/2010 ND VB-1-11D 9/26/2007 ND V'1-1-110 10/18/2008 ND VB-1-11D 10/16/2009 ND VB-1-11D 9/28/2010 ND V1-1-11D 12/18/2010 ND V1-1-12D 12/13/2007 ND VB-1-12D 3/13/2008 ND VB-1-12D 6/11/2008 ND VB-1-12D 9/18/2008 ND VB-1-12D 12/18/2008 ND VB-1-12D 3/12/2009 ND VB-1-12D 6/10/2009 ND VB-1-12D 6/10/2009 ND VB-1-12D 9/16/2009 ND VB-1-12D 12/7/2009 ND VB-1-12D 3/9/2010 ND VB-1-12D 6/10/2010 ND VB-1-12D 9/28/2010 ND VB-1-12D 12/14/2010 ND VB-1-12D 3/15/2011 ND VB-1-12D 6/20/2011 ND VB-1-12D 6/13/2012 ND VB-1-ID 12/16/2005 VB-1-1D 1/4/2006 VB-I-1D 7/24/2006 VB-1-10 12/27/2010 VB-1-10 1/18/2011 VB-1-1D 1/18/2011 VB-I-1D 4/21/2011 ND ND ND ND ND ND ND'Monitoring well locations presented below are on a variety of different sampling schedules, including monthly, quarterly, and comprehensive.
Therefore, not all locations will have the same amount of data available.
In some cases, shallow locations were sampled less frequently due to the presence of an associated deep monitoring well.2Non-detect (ND) below 200 pCi/L (background).
3Non-impacted well results were generally below or near background levels.CMA 16k1 q 44 APPENDIX B GROUNDWATER MODELING RESULTS (Memorandum) 01841 (44) 651 Colby Drive, Waterloo, Ontario, Canada N2V 1 C2 CONESTOG =ROVE=RS Telephone:
(519) 884-0510 Fax: (519) 884-0525& ASSOCIATES www.CRworld.com MEMORANDUM To: Phil Harvey, CRA REF. No.: 016841-74 FROM: Hongze Gao/kf/39 9fXA DATE: October 5, 2012 RE: Evaluation of Tritium Migration after Pumping is Stopped from June 2012 Observed Condition (VB 1 Area)Exelon Generation Company, LLC Braidwood Station, Braceville, Illinois
1.0 INTRODUCTION
Based on the results from the previous modeling studies (CRA, 2006; 2008), pumping from recovery wells in the residual tritium areas at Vacuum Breaker 1 (VB 1) in concurrence with pumping from the Exelon Pond was considered as the most efficient remedial option to clean up the residual tritium associated with the releases from VB 1 area. This pumping operation has been ongoing since October 2006. The continuous observation results demonstrate that the residual tritium area has been shrinking over time to the current measured June 2012 condition (Figure B.1). Currently, only an isolated area of residual tritium above the detection limit remains in the VB 1 area. It is anticipated that this isolated area of residual tritium will dissipate naturally over time without any adverse impact on groundwater, even if all pumping activities are stopped (both from Exelon Pond and from recovery wells RW-5, RW-6 and RW-7).The evaluation of tritium migration after pumping is stopped was performed against the July 2011-February 2012 observed tritium condition by CRA in February 2012 (CRA, February 2012). This study is an update to the previous evaluation to evaluate the tritium migration with the assumption that the pumping is stopped from the June 2012 observed conditions.
The model simulation results demonstrate the future tritium migration conditions after the pumping operations cease. The primary objective of this modeling effort is to evaluate how long it will take for the isolated residual tritium to attenuate and where it will migrate [i.e., with tritium concentrations reduced to below the background level of 200 picocuries per liter (pCi/L)].This memorandum presents the methodology used and the results of the modeling evaluation with respect to the tritium migration from current (i.e., June 2012) conditions after the pumping operation is stopped.2.0 CODE SELECTION The same approached was employed (i.e., utilizing the existing three-dimensional (3D) groundwater flow and transport model developed for the Site). MODFLOW-2000 (Harbaugh et al., 2000) was employed to simulate the groundwater flow, and MT3DMS (Zheng and Wang, 1999) was used to include all the* transport processes (including advection, dispersion and decay) to simulate the further migration of the N6IIITUIAE CIMPNIY FOI ISO 9001 ENMINEERING DESIGN CRA MEMORANDUM Page 2 residual tritium. Groundwater Vistas Version 6 (Rumbaugh, 2011) was employed as the graphical user interface (GUI) to provide pre- and post-processing of groundwater modeling results.3.0 MODELING APPROACH This groundwater modeling effort used the existing Braidwood Site 3D flow and tritium transport model (CRA, 2006; 2008); therefore, all input parameters for the flow and tritium transport were unchanged.
Based on the objective of this modeling study (i.e., to estimate how long it will take for the residual tritium to attenuate naturally, and where it will migrate) a few model simulations were carried out in sequence as follows: 1) Based on the groundwater elevation observation data, the flow conditions did not change significantly between June 2011 and June 2012. Therefore, the simulated steady-state flow condition representing the June 2011 conditions was used as an initial flow condition (i.e., the current flow condition).
The current flow conditions include extraction at wells in the VB 1/2/3 areas and the Exelon Pond pumping.2) The future flow conditions (i.e., groundwater recovery condition after all pumping operations were shut off simultaneously) were simulated in a transient-state to simulate the groundwater elevation recovery process after the pumping was stopped, using the simulated steady-state flow conditions as available from step 1 as an initial flow condition.
The transient flow condition was simulated with two stress periods. The first stress period was 1 year, and the second stress period was 4 years.To maintain computational efficiency, the first stress period was simulated in a transient condition while the second stress period was simulated in a steady-state condition, meaning to represent the stabilized flow condition of the second stress period.3) Residual tritium migration and clean up times for the VB 1 area were simulated using MT3DMS under the transient-groundwater flow condition using the observed residual tritium extent delineated from the available data from June 2012 as an initial concentration condition.
The total simulation duration was set to be 5 years.4.0 ESTIMATE OF CLEANUP TIMES The simulated area of residual tritium at the end of day 540 is presented on Figure B.2. The figure demonstrates that the extent of residual tritium will shrink while the center of the residual area may migrate slightly further downgradient near the ditch on Exelon's property (Figure B.2) from the current location and will eventually reduce to below the background value of 200 pCi/L in less than 570 days (the next time step after 540 days) after the pumping cessation.
5.0 CONCLUSION
S The following conclusions can be drawn based on the model simulation results:* It will take less than 570 days (or 1.6 years) for the existing area of residual tritium at VB 1 to naturally attenuate to below the background level after the current pumping operations at the Exelon Pond and the recovery wells are stopped.
CRA MEMORANDUM Page 3* The existing area of residual tritium at the VB 1 area will migrate slightly further away from the current location and will dissipate near the ditch on Exelon's property." The current isolated area of residual tritium in the groundwater will not cause an adverse impact to the adjacent properties, even when the pumping operations are shut down completely at both the recovery wells RW-5/6/7 and Exelon Pond.
6.0 REFERENCES
CRA, 2006. Groundwater Flow and Tritium Transport Modeling, Braidwood Generating Station, Braceville, Illinois, August.CRA, 2008. Simulation of Aggressive Remedial Option (VB-2 and 3), Exelon Generation Company, LLC Braidwood Station, Braceville, Illinois, January.CRA, February 2012. Evaluation of Tritium Migration after Pumping is Stopped (VB 1 Area).Harbaugh, A.W., E.R. Banta, M.C. Hill, and M.G. McDonald, 2000. MODFLOW-2000, The U.S. Geological Survey Modular Ground-Water Model -User Guide To Modularization Concepts And The Ground-Water Flow Process, United States Geological Survey Open-File Report 00-92, Reston, Virginia.McDonald, M.G. and A.W. Harbaugh, 1988. A Modular Three-Dimensional Finite-Difference Ground-Water Flow Model, United States Geological Survey Techniques of Water-Resources Investigations, Book 6, Chapter Al.Zheng, C., and P. Wang, 1999. MT3DMS: A Modular Three-Dimensional Multispecies Transport Model for Simulation of Advection, Dispersion, and Chemical Reactions of Contaminants in Groundwater Systems; Documentation and User's Guide. Prepared by University of Alabama, Prepared for US Army Corps of Engineers.
Rumbaugh, J.O and J.B Rumbaugh, 2011. Guide to Using Groundwater Vistas, Version 6, Environmental Simulations Inc., Herndon, Virginia.
FATLAN POND F-4D 0 150 300ft F-ID EXELON POND 41D MW-19 V81-00 1310 40=7VS-I-7D VLLDS-- VS-I-S<.LLD-D VB-1-gD MONITORING WELL ID (E) -LLD 917 OBSERVED TRITIUM 4=L D-ID..........
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