ML14030A287
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.4PLAN COMPLETION REPORT FOR THE VB 6 AREABRAIDWOOD GENERATION STATIONBRACEVILLE, ILLINOISPrepared For:Exelon Generation
- Company, LLCDISCLAIMER:
SOME FORMATTING CHANGES MAY HAVE OCCURRED WHENTHE ORIGINAL DOCUMENT WAS PRINTED TO PDF; HOWEVER,THE ORIGINAL CONTENT REMAINS UNCHANGED.
Prepared by:Conestoga-Rovers
& Associates 8615 West Bryn MawrChicago, Illinois 60631AUGUST 2009REF. NO. 046907 (7)This report is printed on recycled paper.Office: (773) 380-9933Fax: (773) 380-6421web: http:\\www.CRAwodd.com b.TABLE OF CONTENTSPage
1.0 INTRODUCTION
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11.1 BACKGROUND AND PURPOSE ................................................................
11.2 DESCRIPTION OF THE REMEDIATION AREA .....................................
21.3 SUMMARY OF REMEDIAL ACTIONSTO DATE AND CURRENT GROUNDWATER CONDITIONS
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22.0 CURRENT GROUNDWATER CONDITIONS AT VB 6 ..............................................
32.1 BACKGROUND
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32.2 PRE-REMEDIATION GROUNDWATER CONDITIONS
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32.3 REMEDIAL ACTION PLAN IMPLEMENTED AT VB 6 .........................
42.4 CURRENT GROUNDWATER CONDITIONS
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42.5 EVALUATION OF REMEDIAL ACTIVITIES TO DATE ........................
53.0 CONCLUSION
S
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74.0 PLANNED COMPLETION ACTIVITIES
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85.0 REFERENCES
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9046907(7)
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& AssoctATEs LIST OF FIGURES(Following Text)FIGURE 1.1FIGURE 1.2FIGURE 2.1FIGURE 2.2FIGURE 2.3FIGURE 2.4FIGURE 2.5FIGURE 2.6FIGURE 2.7FIGURE 2.8SITE LOCATION MAPLOCATION MAP FOR VB 6 AREAMONITORING WELL LOCATIONS
-VB 6GROUNDWATER LEVEL CONTOURS
-MARCH 2006 -SHALLOWGROUNDWATER ZONEGROUNDWATER LEVEL CONTOURS
-MARCH 2006 -DEEPGROUNDWATER ZONEESTIMATED TRITIUM RESULTS -MARCH 2006 -SHALLOWGROUNDWATER ZONEESTIMATED TRITIUM RESULTS -MARCH 2006 -DEEP GROUNDWATER ZONETRITIUM CONCENTRATION TRENDS AROUND VB 6 AREAGROUNDWATER LEVEL CONTOURS
-VB 6 AND VB 7 AREAS -SEPTEMBER 15-18, 2008ESTIMATED TRITIUM RESULTS -SEPTEMBER 2008 -VB 6GROUNDWATER ZONE048907 (7) CONESTOGA-ROVERS
& ASSOCIATES 046907 (7)CONESTOGA-ROVERS
& AssocIATES "ILIST OF TABLES(Following Text)TABLE 2.1TABLE 4.1SUMMARY OF TRITIUM STATISTICAL ANALYSES NEAR VB 6SUMMARY OF WELLS TO BE ABANDONED 048907(7)
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41.0 INTRODUCTION
1.1 BACKGROUND AND PURPOSEThis document has been prepared for the Illinois Environmental Protection Agency(IEPA) to address on-going groundwater remediation at the Exelon Generation Company LLC (Exelon)
Braidwood Generating Station property' located in Braceville, Illinois.
More specifically, this Plan Completion Report addresses the Vacuum Breaker#6 area (Site) and discusses the groundwater investigation, monitoring, and remedialactions that were implemented in accordance with the Agreed Preliminary Injunction Order (PIO) dated May 24, 2006. Information collected to date as a result of Action Planimplementation is sufficient to determine that remediation at the VB 6 area is completeand can be concluded.
Among other things, the May 24, 2006 PIO required Exelon to submit a Groundwater Action Plan to address tritium in groundwater at or near Braidwood Generating Station's Vacuum Breaker #6 (VB 6). In November 2006, the Minimization Impairment Plan for Vacuum Breaker 6 was prepared and submitted to the IEPA (hereinafter referred to as the "Action Plan"). Upon approval by the IEPA, the Action Plan wasimplemented.
As a result of the implementation of the approved Action Plan, the levels of tritiumdetected in groundwater have been reduced to below the Lower Level of Detection (LLD) of 200 picocuries per liter (pCi/L) in the VB 6 area. Additionally, a significant amount of environmental data has been collected as part of the Action Planimplementation.
Analyses of these data have revealed the geologic and hydrogeologic characteristics of the subject area, providing an understanding of the groundwater movement and tritium migration.
This Plan Completion Report for the VB 6 area isbased on Site characterization data collected through May 2009 which indicate asubstantial reduction in tritium levels through passive remediation.
Information collected to date as a result of Action Plan implementation is sufficient todetermine that remediation at the VB 6 area is complete and can be concluded.
Section 5.0 of this Plan Completion Report provides a list of references specific to theVB 6 area as well as pertinent documents related to the other areas on the Braidwood Station property where remediation of tritium in groundwater is being performed.
1 The Braidwood Station property includes lands listed under the Station's Nuclear Regulatory Commission (NRC) licensed property along the blowdown line and property recently purchased byExelon along Smiley Road and Center Street.046907 (7)1CONEsToGA-ROVERS
& AssociATEs 1.2DESCRIPTION OF THE REMEDIATION AREALand surrounding the VB 6 area falls mainly into the agricultural, residential, andrecreational use categories (Figure 1.1). The center of the Village of Braidwood isapproximately 10,000 feet from the vacuum breaker VB 6. To the northwest of the Site,there are two main highways (Illinois State Highway 53 and Illinois Route 129) runningparallel to each other with a railroad (Southern Pacific Railroad) between them. TheWill County Forest Preserve is located to the north of the Site. Five monitoring wellshave been installed in the vicinity of the Site (Figure 1.2).1.3 SUMMARY OF REMEDIAL ACTIONSTO DATE AND CURRENT GROUNDWATER CONDITIONS The current groundwater remediation program for the VB 6 area utilizes passivetechniques, which includes monitored natural attenuation (MNA).The concentration of tritium in groundwater at monitoring wells in the VB 6 area hasbeen reduced by as much as 100% since September 2006 (e.g., MW-148D and MW-150D).
As of May 2009, tritium concentrations in groundwater samples collected from all themonitoring wells at the VB 6 location were below the LLD of 200 pCi/L. All monitoring wells at the VB 6 location have been below the LLD for six consecutive sampling eventssince December 2007.046907(7) 2 CONESTOGA-ROVERS
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& AssoctATEs 2.0 CURRENT GROUNDWATER CONDITIONS AT VB 6This section presents a description of the pre-remediation and current groundwater conditions at the VB 6 area.2.1 BACKGROUND Vacuum breaker VB 6 is located on the blowdown line about 425 yards east of EssexRoad and 450 yards north of Smiley Road on the Exelon transmission towerright-of-way (Figure 1.2). This land is leased to a local resident for agriculture.
The WillCounty Forrest Preserve District (WCFPD) owns the property directly north of theright-of-way.
A search of work history for leaks from the VB 6 and its associated air release valvedetermined the following:
- Engineers discovered minor leakage of the main seat on November 10, 2000. Thevalve had been previously verified leak free on March 3, 2000.* Another main seat leak with the same description was discovered on October 30,2003. This leak was repaired on October 17, 2005.2.2 PRE-REMEDIATION GROUNDWATER CONDITIONS A total of 20 monitoring wells have been installed into the deep and shallow zones of theoverburden sand aquifer in the VB 6 area. The majority of these monitoring wells havebeen abandoned.
Currently, there are five monitoring wells in the VB 6 area used forroutine groundwater monitoring.
Figure 2.1 presents the monitoring well network inthe vicinity of VB 6. This figure includes temporary 1-inch diameter monitoring wellsand permanent 2-inch diameter monitoring wells.Figures 2.2 and 2.3 present the groundwater elevations and flow directions in theshallow and deep zones of the overburden sand aquifer for March 2006, respectively.
Groundwater in the vicinity of VB 6 flows generally northeast in the deep zone.Figures 2.4 and 2.5 present the estimated horizontal distribution of tritium in the vicinityof VB 6 in the shallow and deep zones of the overburden
- aquifer, respectively, in thewinter of 2005. These figures indicate that the highest tritium concentrations weredowngradient of VB 6.046907 (7)3CONEsToGA-ROVERS
& AssocIATES 2.3REMEDIAL ACTION PLAN IMPLEMENTED AT VB 6The remedial action plan selected for the VB 6 area and approved by the IEPA is MNA.The monitoring phase of the plan was designed to insure that the residual levels oftritium in groundwater did not further impair groundwater for current groundwater users (those outside the limits of the Station's property).
This monitoring program wasspecifically designed to assess and evaluate residual levels of tritium in groundwater.
Since the winter of 2005, Exelon has been monitoring tritium levels in groundwater nearthe VB 6 area. As a result, more than 3.5 years of data, including groundwater levelsand tritium concentrations, has been collected.
More specifically, in September 2006,Exelon implemented routine quarterly groundwater monitoring as part of the ActionPlan described above. Since implementation of the Action Plan, an additional 11quarters of sampling data has been collected,
- analyzed, and submitted to the IEPA forevaluation.
This groundwater monitoring is in addition to the Nuclear Regulatory Commission (NRC) required groundwater sampling performed under the Station's Radiological Environmental Monitoring Program (REMP).Groundwater flow and tritium transport modeling performed at the VB 6 area waspresented in the report prepared by CRA entitled "Groundwater Flow and TritiumTransport
- Modeling, Braidwood Generating Station" (CRA, August 2006). Themodeling indicated that the tritium in the VB 6 area would not impact groundwater users off the Station property.
The modeling results presented in this report also suggestthat 200 pCi/L would be reached within a few years at locations off the licensedproperty.
2.4 CURRENT GROUNDWATER CONDITIONS The current trends of decreasing tritium concentrations within groundwater at the VB 6area (January 2006 through May 2009) have been depicted on Figure 2.6 and in Table 2.1.Table 2.1 provides a summary of the statistical analyses of the monitoring wells sampledgenerally between the time period from January 2006 to May 2009. These analysesindicate a predominately downward trend of tritium concentrations in the groundwater monitoring wells in the vicinity of VB 6. Three monitoring wells in the VB 6 area weresampled and continue to indicate levels of tritium below the LLD of 200 pCi/L fromJanuary 2006 and May 2009 and therefore were excluded from the statistical analysis.
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& AssociATEs Two monitoring wells that have had tritium detected at concentrations greater than200 pCi/L between January 2006 and May 2009 were utilized for statistical analysis.
Theoverall percent reduction of tritium concentrations between January 2006 and May 2009is also presented in Table 2.1. Tritium concentrations have been reduced by as much as100% from 520 pCi/L in September 2006 to less than the LLD of 200 pCi/L in May 2009,as shown at locations MW-148D and MW-150D.
Groundwater samples collected frommonitoring wells in the VB 6 area are at levels significantly below the drinking waterstandard of 20,000 pCi/L and, in fact, all sample data are currently less than the LLD of200 pCi/L. Figure 2.6 presents the predominately downward trend in tritiumconcentrations over time at select monitoring wells in the VB 6 area.Figure 2.7 provides the September 2008 groundwater level contours.
Groundwater flowin the vicinity of VB 6 is generally towards the northeast.
Figure 2.8 provides the September 2008 estimated tritium results.Previous BIOSCREEN modeling in 2006 of the area indicated that tritium concentrations would not exceed 200 pCi/L beyond approximately 490 feet from the sourceconcentration.
Previous modeling results estimated that steady state would be achievedin 15 years. In less than 2 years after the initial modeling
- results, all sampled monitoring well locations in the VB 6 area had tritium concentrations less than the LLD of200 pCi/L.2.5 EVALUATION OF REMEDIAL ACTIVITIES TO DATEA review of the groundwater data, evaluations, and graphical presentations provided inTable 2.1 and on Figures 2.4 through 2.8 provides sufficient information to document thefollowing:
" There is no groundwater in this area that is above the drinking water standard of20,000 pCi/L;" As of May 2009 tritium concentrations in all sampled monitoring wells in this areaare less than the LLD of 200 pCi/L;* The average reduction in tritium concentrations per monitoring well is 100%;* With the exception of one out of two monitoring wells in this area utilized forstatistical
- analysis, the trend in tritium concentrations in routine sampling events hasbeen downward.
For one monitoring well a statistical trend could not be identified since the majority of results for that location were below LLD; and046907 (7)5CONESTOGA-ROVERS
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- The maximum extent of tritium migration in the VB 6 area has been limited to lessthan 52 feet2 from time of discovery in later 2005 and early 2006.Based on the results of the monitoring
- program, no detectable levels of tritium ingroundwater above the LLD of 200 pCi/L, it is apparent that the MNA remedy provedsuccessful in reducing tritium levels both on and off the Station property.
2 The maximum extent was determined based upon the estimated plume length in 2006.046907 (7)6CONEsToGA-ROVERS
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3.0 CONCLUSION
S The previous sections of this Plan Completion Report have identified the nature andextent of tritium in groundwater near VB 6 and the progress of the remediation completed over the last 3.5 years. This information demonstrates the success of thecleanup of tritium in groundwater at VB 6 area.Specifically, the following remedial objectives have been met for the VB 6 area:" Concentrations of tritium in groundwater from the vacuum breaker releases arebelow the drinking water standard of 20,000 pCi/L; and* Any residual concentrations of tritium will not impact off-Site, private groundwater users; all monitoring wells are currently less than the LLD of 200 pCi/L.These remedial objectives are documented through the following facts:" All VB 6 area monitoring wells are below 20,000 pCi/L and have been sinceDecember 2005; and" All tritium concentrations as of May 2009 are below 200 pCi/L and have had areduction of 100% since September 2006.046907 (7) 7 CON ESTOGA-ROVERS
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& AssocIATES 4.0 PLANNED COMPLETION ACTIVITIES Groundwater sampling and analyses for tritium at the VB 6 area will be eliminated, andall monitoring wells will be plugged and abandoned.
The monitoring wells to beabandoned are listed in Table 4.1.046907(7) 8 CONESTOGA-ROVERS
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5.0 REFERENCES
CRA, March 2006. Tritium Investigation, Exelon Generation
-Braidwood Station.CRA, March 2006, Interim Remedial Action Plan, Exelon Generation
-Braidwood Station.CRA, May 2006. Agreed Preliminary Injunction Order.CRA, June 2006. Migration Control Plan, Vacuum Breaker 1, Braidwood Generation
- Station, Braceville, Illinois.
CRA, June 2006. Migration Control Plan, Vacuum Breakers 2 and 3, Braidwood Generation
- Station, Braceville, Illinois.
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. Wedron Clay Till Investigation Report, Braidwood Generating
- Station, Braceville, Illinois.
CRA, December 2006. CRA Memorandum, Transient Groundwater Flow ModelCalibration and Transport Model Scenario Update.CRA, January 2007, 2006 Annual Groundwater Sampling Report, Tritium Remediation
- Program, Braceville, Illinois.
- 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 96-485, Reston, Virginia.
- McDonald, M.G. and A.W. Harbaugh, 1988. A modular Three-Dimensional Finite-Difference Ground-Water Flow Model, United States Geological SurveyOpen-File Report 83-875.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 ToModularization Concepts And The Ground-Water Flow Process, United StatesGeological Survey Open-File Report 00-92, Reston, Virginia.
046907 (7)9CONESTOGA-ROVERS
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- Pollock, D.W., 1994. User's Guide for MODPATH/MODPATH-PLOT, Version 3: Aparticle tracking post-processing package for MODFLOW, the U.S. Geological Survey finite-difference ground-water flow model: U.S. Geological SurveyOpen-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, andChemical Reactions of Contaminants in Groundwater Systems; Documentation and User's Guide. Prepared by University of Alabama, Prepared for US ArmyCorps of Engineers.
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- rý CDlA )46txnxVS-I AVa-1-I 0APPROXIMATE BLOWDOWN PROPERTY LINESLOWDOWN LIEMAK(EUP LIEVACUUM BREAK(ERMID POINT MONITORING WELL LOCATION AND IDENTITjR VACUUM BREAKER MONITOJRING WELL LOCATION AND WDENIMERfigure 1.2LOCATION MAP FOR VB 6 AREAEXELON GENERATION BRAIDWOOD STATIONBra"vi/te, I/inois FOREST PRESERVE-- ----------------------
410 201tVB-.6,o YAM V8-oMW-150Osovs4-"ID volmpVB-6-l MWl14BOE VBd4-5VB-6-~4 4-VE60 MW-48D VB--61)III L-23VB-64D* V94B 0 ________VB-6630LEGENDAPPROXIMATE SLOWDOMWN PROPERTY LINED EMW-14-D AUGUST 2006 PERMANENT MONITORING WELL LOCATIONMAKUPLIN V___2 M WL.,BEENANDOWD figure 2.1TREEUNE MONITORING WELL LOCATIONS
-VB 6GROUNDWATER MONITORING PROGRAMVB-3 A VACUUM BREAKER LOCATION EXELON GENERATION BRAIDWOOD STATIONBL-23 W B-WIWOOWN UNE MONITORING r=^,mdzo IllmihVS 54W r,,ss., SISI55~IC 46W07-00(07)N-C0003 AUG I111200 FOREST PRESERVE0 10 20tt(V5 -.70(5a242)*V9-I-(582A3)V114 AVs,.3-76(512.42)LEGENDAPPROXIMATE SLOWDOWN PROPERLY LIESLOWDOWN LINEMAKEUP LINETREELINVACUUM BREAKER LOCATIONSHAL.LOW VACUUM BREAKER SAMPUNG LOCATIONGROUNDWATER ELEVATION (f AMSL)GROUNDWATER ELEVATION CONTOUR (3AUG14GROUNDWATER FLOW DIRECTION figure 2.2GROUNDWATER LEVEL CONTOURS
-MARCH 2006SHALLOW GROUNDWATER ZONEEXELON GENERATION BRAIDWOOD STATION (VB 6)Brnaiclle, Ilhmil 0FOREST PRESERVE0 10 20fm-----------------------------------
VB-6-6D(582.46)VB-S-7D(582,43)0(582.26) 5VB2-&D(58,08)VB-6-5D(682.34)( .VB-642D(SS2.63)_
VB6 5829( 582.42)VS-3iAV(5I-23 4(511234)==82LEGENDAPPROXIMATE SLOWDOWN PROPERTY LINESLOWDOWN LINEMAKEUP LINEVACUUM BREAKER LOCATIONDEEP VACUUM BREAKER SAMPLING LOCATIONGROUNDWATER ELEVATION (It AMSL)GROUONDWATER ELEVATION (ft AMSL)GROUNDWATER FLOW DIRECTION figure 2.3GROUNDWATER LEVEL CONTOURS
-MARCH 2006DEEP GROUNDWATER ZONEEXELON GENERATION BRAIDWOOD STATION (VB 6)Braceavlle, Il/lins4SW0-00OOTGN-C=5O AUG I1112=0 FOREST PRESER-IVE 0 10 20ft(NO)VB-S-iO(ND)Ve-49--VB-6-6(ND4(ND) VEI8VS-6-3LEGEND-APPROXIMATE BLOWDOWN PROPERTY LINEBLOWDOWN LINEMAKEUP LINETREEUNEVB-3 A VACUUM BREAKER LOCATIONVs-3-70 SHALLOW VACUUM BREAKER SAMPLING LOCATION(2.125) TRIIUM RESULT IN GROUNDWATER pCIpL)-209-- TRITUM CONTOURTRITIUM RESULTS 200 TO SA000 (pC.L)TRITIUM RESULTS 0 TO 200(ND) NON-DOETECT BELOW 200 paYLNOTE.BACKGROUND TRITIUM CONCENTRATION:
200 pCV.DRINKING WATER STANARD FOR TRITIUM 20.000 paLMOST RECENT TRITUM RESULTS FOR SAMPLESCOLLECTED THROUGH MARCH 2 2006. CONTOURS WEREGENERATED USING LOG VALUES.figure 2.4ESTIMATED TRITIUM RESULTS -MARCH 2006SHALLOW GROUNDWATER ZONEEXELON GENERATION BRAIDWOOD STATION (VB 6)Bracev/ole, Iliniois4U0l74WW7)GN4XAUG IV2O0 0FOREST PRESERVE0 10 205-- --------- ---------- -------------------------------------(NO)VB-oIU(NO)is IND)V(NO-i)(ND)(ND)(ND)LEGEND-APPROXIMATE BLOWDOWN PROPERTY UNEBLOWDOWN UNEMAKEUPL UNETREELINEVB-3 A VACUUM BREAKER LOCATIONVBS-1D 1 DEEP VACUUM BREAKER SAMPLNG LOCATION(79) TRITIUM RESULT IN GROUNDWATER (pCIL)(ND) NON-DETECT BELOW 200 pCULNOTE:BACKGROUND TRITIUM CONCENTRATION:
200 pCIYLDRINKING WATER STANDARD FOR TRITIUM:
20.000 pCULMOST RECENT TRITIUM RESULTS FOR SAMPLESCOLLECTED THROUGH MARC4 6, 2006.figure 2.5ESTIMATED TRITIUM RESULTS -MARCH 2006DEEP GROUNDWATER ZONEEXELON GENERATION BRAIDWOOD STATION (VB 6)Bracevie, Illinois41.Ji(7-UWJ7N-PJ AUG 11IrU FIGURE 2.6TRITIUM CONCENTRATION TRENDS AROUND VB 6 AREAEXELON GENERATION BRAIDWOOD STATIONBRACEVILLE, ILLINOIS10000010000CL000.E100010010--- MW-148D-MW-150D-20,000 pCVL-200 pCi/L0m D0 0000 00NNNNNN 0 0 0 E E-c mDatev4 0 175 350ftLEGENDVB-6 .AMW-15D *(595.43)
LINEGROUNDWATER ELEVATION CONTOURGROUDWATER FLOW DIRECTION VACUUM BREAKER LOCATIONMONITORING WELL LOCATION AND IDEfGROUNDWATER ELEVATION (FT. AMSL)figure 2.7GROUNDWATER LEVEL CONTOURS
-VB 6 AND VB 7 AREASSEPTEMBER 15-18, 2008EXELON GENERATION BRAIDWOOD STATIONBraceville, Illinois469o7 (7)
FOREST PRES.RVE--------------------
0 10 204VS-" 71 VS4,870MW-1500(ND)am V84-"oVSB6-IDI
((ND)MW-149Dthiml'LM148D6v0~&4oS VD-6oV"4D V" \8-62D* B-* BL-23'wVS-6-3Va-6-SOr-APPRO)XMATE SLOWWN PROPERTY LINE--S~~~LOWDOWN UNME~.AGS206PRAETM~lRIGWU OAI#MAKEUP UNE V842 I s .SHA E ORf r______figure 2.8TEEEUNE ESTIMATED TRITIUM RESULTS-SEPTEMBER 2008Va-SA VACUUM BREAKER LOCAllON B6 G O N W T R Z EVB 6 GROUNDWATER ZONEM.-23 M EXELON GENERATION BRAIDWOOD STATION4U07~(OO7QSCAUbG I IRMBra~cevile, Illinois TABLE 2.1Page 1 of 3SUMMARY OF TRITIUM STATISTICAL ANALYSES NEAR VB 6EXELON GENERATION BRAIDWOOD STATIONBRACEVILLE, ILLINOISSampleDateResult1(pCi/L)PercentReduction 2Minimum MaximumSample LocationTrendMW-148DMW-148DMW-148DMW-148DMW-148DMW-148DMW-148DMW-148DMW-148DMW-148DMW-148DMW-150DMW-150DMW-150DMW-150DMW-150DMW-150DMW-150DMW-150DMW-150DMW-150DMW-150D9/11/2006 11/7/2006 3/15/2007 6/12/2007 9/13/2007 12/13/2007 3/11/2008 6/9/20089/16/2008 12/17/2008 3/12/2009 9/11/2006 11/7/2006 3/15/2007 6/11/2007 9/13/2007 12/13/2007 3/11/2008 6/9/20089/16/2008 12/17/2008 3/12/2009 477227NDNDNDNDNDNDNDNDND52015551352403290NDNDNDNDNDNDNo trend identified 100%ND477Downward trend100%ND1555AverageAverage MIN MAX Reduction 3Downward trend 100% ND 1555.0 100%Non-Impacted Wells 4BL-23BL-23BL-23BL-23BL-23BL-23BL-23BL-23BL-23BL-236/2/20067/10/2006 8/15/2006 9/12/2006 10/10/2006 11/7/2006 12/11/2006 1/9/20072/14/2007 3/15/2007 NDNDNDNDNDNDNDNDNDNDCRA 0469( M TABLE 2.1Page 2 of 3SUMMARY OF TRITIUM STATISTICAL ANALYSES NEAR VB 6EXELON GENERATION BRAIDWOOD STATIONBRACEVILLE, ILLINOISSample Result' PercentSample Location Date (pCi/L) Trend Reduction 2 Minimum MaximumBL-23 4/13/2007 NDBL-23 5/15/2007 NDBL-23 6/12/2007 NDBL-23 7/10/2007 NDBL-23 8/14/2007 NDBL-23 9/12/2007 NDBL-23 10/17/2007 NDBL-23 11/14/2007 NDBL-23 12/13/2007 NDBL-23 1/15/2008 NDBL-23 3/13/2008 NDBL-23 4/17/2008 NDBL-23 5/14/2008 NDBL-23 6/10/2008 NDBL-23 7/15/2008 NDBL-23 8/12/2008 NDBL-23 9/16/2008 NDBL-23 10/14/2008 NDBL-23 11/11/2008 NDBL-23 12/16/2008 NDBL-23 1/14/2009 NDBL-23 2/10/2009 NDBL-23 3/12/2009 NDBL-23 4/16/2009 NDBL-23 5/12/2009 NDMW-149D 9/11/2006 NDMW-149D 11/7/2006 NDMW-149D 3/15/2007 271MW-149D 6/11/2007 NDMW-149D 9/13/2007 NDMW-149D 12/13/2007 NDMW-149D 3/11/2008 NDMW-149D 6/9/2008 NDMW-149D 9/16/2008 NDMW-149D 12/17/2008 NDMW-149D 3/12/2009 NDVB-6-1 12/20/2005 NDVB-6-1 1/3/2006 NDVB-6-1 7/11/2006 NDVB-6-1 8/15/2006 NDVB-6-1 9/11/2006 NDVB-6-1 10/9/2006 NDCRA 046907 TABLE 2.1Page 3 of 3SUMMARY OF TRITIUM STATISTICAL ANALYSES NEAR VB 6EXELON GENERATION BRAIDWOOD STATIONBRACEVILLE, ILLINOISSampleDateResult'(pCVL)PercentReduction 2Minimum MaximumSample LocationTrendVB-6-1VB-6-1VB-6-1VB-6-1VB-6-1VB-6-1VB-6-1VB-6-1VB-6-1VB-6-1VB-6-1VB-6-1VB-6-1VB-6-1VB-6-1VB-6-1VB-6-1VB-6-1.VB-6-1VB-6-1VB-6.-1VB-6-1VB-6-1VB-6-1VB-6-1VB-6-1VB-6-111/7/2006 12/11/2006 1/9/20072/14/2007 3/15/2007 4/11/2007 5/15/2007 6/11/2007 7/9/20078/14/2007 9/12/2007 10/17/2007 11/13/2007 12/13/2007 1/15/2008 2/13/2008 3/11/2008 8/12/2008 9/16/2008 10/14/2008 11/11/2008 12/16/2008 1/13/2009 2/10/2009 3/12/2009 4/15/2009 5/12/2009 NDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNDNote: January 2006 data was used as initial concentrations for statistical analysis where available.
'Non-detect (ND) below 200 picocuries per liter (pCi/L).2 Monitoring Well locations with the most current data at ND were assumed to have 100% reduction.
3Average Reduction excludes well locations with a percent increase in concentration.
- Non impacted well were generally below or near the LLD and were excluded from statistical analysis.
CPA 046907 (7)
TABLE 4.1Page 1 of 1SUMMARY OF WELLS TO BE ABANDONED EXELON GENERATION BRAIDWOOD STATIONBRACEVILLE, ILLINOISVacuum Breaker Area Sample LocationVacuum Breaker 6 BL-23MW-148DMW-149DMW-150DVB-6-1CRA 046907(7)