Enclosure 3Error # Error Description Correction Originator Responsibility StatusDate ofCompletion1 EPA comment 1-C-15In Appendix SOTERM-2009, Table SOTERM-21,the parameter descriptions for PHUMCIM andPHUMSIM indicate "actinide solubilities areinorganic only (complexes with man-made organicligands are not important); solubilities werecalculated assuming equilibrium with Mg-bearingminerals (brucite and magnesite)." DOE shouldcorrect these statements to clarify that organicligands were considered during calculation of thesolubilities used with these proportionality constantsfor the CRA-2004 PABC, and that the solubilitieswere calculated assuming equilibrium with bruciteand hydromagnesite.The description for PHUMCIM in AppendixSOTERM-2009, Table SOTERM-21 should bechanged to “Proportionality constant forconcentration of actinides associated withmobile humic colloids; in Castile brine;actinide solubilities include organics(complexes with man-made organic ligands);solubilities are calculated assumingequilibrium with Mg-bearing minerals (bruciteand hydromagnesite)."EPA LANL-Reed Revised textincluded in 1stResponseSubmittal to theEPASubmitted to EPAin 1st ResponseAug 24, 20092 EPA comment 1-C-15In Appendix SOTERM-2009, Table SOTERM-21,the parameter descriptions for PHUMCIM andPHUMSIM indicate "actinide solubilities areinorganic only (complexes with man made organicThe description for PHUMSIM in AppendixSOTERM-2009, Table SOTERM-21 should bechanged to “Proportionality constant forconcentration of actinides associated withmobile humic colloids; in Salado brine;EPA LANL-Reed Revised textincluded in 1stResponseSubmittal to theEPASubmitted to EPAin 1st ResponseAug 24, 2009CRA 2009 ErrataTrackinginorganic only(complexes withman-made organicligands are not important); solubilities werecalculated assuming equilibrium with Mg-bearingminerals (brucite and magnesite)." DOE shouldcorrect these statements to clarify that organicligands were considered during calculation of thesolubilities used with these proportionality constantsfor the CRA-2004 PABC, and that the solubilitieswere calculated assuming equilibrium with bruciteand hydromagnesite.mobilehumic colloids;inSaladobrine;actinide solubilities include organics(complexes with man-made organic ligands);solubilities are calculated assumingequilibrium with Mg-bearing minerals (bruciteand hydromagnesite).”EPAPage 1 of 11Enclosure 33 EPA comment 1-C-18In Appendix MgO-2009, Section 4.2.2, DOE claimsthat hydromagnesite will completely convert tomagnesite during the 10,000 year WIPP regulatorytime period. However, DOE's evaluation of thelikely conversion of hydromagnesite to magnesiteignores information about this issue presented inSCA (2008). As part of a thorough evaluation of thelikely conversion rate for hydromagnesite tomagnesite, SCA (2008) cited data from Vance et al.(1992) that showed hydromagnesite can persist foras long as 6,200 years. In addition, DOE does notconsider that slow CPR degradation will result incontinuous brucite carbonation during the 10,000-year regulatory period, rather than hydromagnesiteformation that occurs only for a short time followingrepository closure.Consequently, even if hydromagnesite formed inthe repository converts to magnesite within a fewthousand years, hydromagnesite is likely to remainin the repository and would be likely to influencecarbon dioxide fugacity for the entire 10,000-yearregulatory period. DOE should revise thisdiscussion to show that hydromagnesite is likely tobepresent in the backfill throughout the WIPPThe following statement should be added atthe end of Subsection 4.2.2 of Appendix MgO2009 to clarify the text in this subsection:“Based on the evidence discussed above, theDOE concludes that it is still unclear whetherhydromagnesite will persist or convert tomagnesite during the 10,000-year WIPPregulatory period. However, the EPA hasspecified that the brucite-hydromagnesite(5424) reaction be used to buffer the CO2fugacity for compliance-related actinidesolubility calculations since the CCA PAVT(Trovato, 1997; U.S. EPA, 1998).”EPA SNL-Brush Revised textincluded in 1stResponseSubmittal to theEPASubmitted to EPAin 1st ResponseAug 24, 2009be p ese t t e bac t oug out t eregulatory period.Page 2 of 11Enclosure 34 EPA comment 1-C-19In Appendix MgO-2009, Section 5.1, DOE statesthat the actinide solubilities in WIPP brinescalculated for the CRA-2004 PA and CRA-2004PABC differed because of “changes in thethermodynamic databases for the An(III), An(IV),and An(V) models.” The thermodynamic databasefor the An(lV) model changed between these twoPA calculations when the chemical potential(μ0/RT) for Th(OH)4(aq) was revised. On the otherhand, the An(III) and An(V) solubility resultschanged because of a recalculation of ligandconcentrations. EPA was not informed of anychanges to the thermodynamic data for the An(III)and An(V) oxidation states. DOE should eithercorrect this statement or document the revisedthermodynamic data.The statement that, “The An(III), An(IV), andAn(V) solubilities predicted for the CRA-2004PA and PABC calculations are different forboth brines because of changes in thethermodynamic databases for the An(III),An(IV), and An(V) models between thesecalculations” (U.S. DOE, 2009, AppendixMgO, Subsection 5.1, p. MgO-32), isincorrect. It should state, “The An(III)solubilities predicted for the CRA-2004 PAand PABC calculations are different for bothbrines because of an increase in theconcentration of EDTA (compare Brush andXiong, 2005, Table 4, columns labeled “CRA2004 PA” and “PABC”). The An(IV),solubilities predicted for the CRA-2004 PAand PABC calculations are different for bothbrines because of changes in thethermodynamic database for An(IV). TheAn(V) solubilities predicted for the CRA-2004PA and PABC calculations are different forboth brines because of the inclusion of thesolubility-limiting phase whewellite (Caoxalate·2H2O) in the FMT database, whichdecreased the dissolved oxalateconcentration despite an increase in theEPA SNL-Brush Revised textincluded in 1stResponseSubmittal to theEPASubmitted to EPAin 1st ResponseAug 24, 2009co ce t at o desp te a c ease t econcentration of oxalate prior to precipitationof whewellite (compare Brush and Xiong,2005, Table 4, columns labeled “CRA-2004PA” and “PABC”).Page 3 of 11Enclosure 35 EPA comment 1-C-20In the discussion of MgO uncertainties (AppendixMgO-2009, Section 6.2.4.4), DOE does not includethe uncertainties associated with the chemicalcomposition of the cellulose, plastics, and rubber inthe WIPP inventory. DOE should acknowledge thisuncertainty in the discussion.The following statement should be added atthe end of the first paragraph of Subsection6.2.4.4.1 of Appendix MgO-2009, “Vugrin etal. (2006) did not include uncertaintiesassociated with the chemical compositions ofthe CPR materials in the WIPP inventory.However, the DOE acknowledges that thereare uncertainties associated with thechemical compositions of these materials.”EPA SNL-Brush Revised textincluded in 1stResponseSubmittal to theEPASubmitted to EPAin 1st ResponseAug 24, 20096 EPA comment 1-C-21Appendix PA-2009, Table PA-10 does not includeunits for the concentrations, which should bemoles/LThe units moles/L should be added toAppendix PA-2009, Table PA-10.EPA SNL-Clayton Revised textincluded in 1stResponseSubmittal to theEPASubmitted to EPAin 1st ResponseAug 24, 20097EPA comment 1--In Appendix PA-2009, Section 4.9, page PA-EPASNL-ClaytonRevised textSubmitted to EPAEPAcomment1 C 22Appendix PA-2009, Section 4.9 includes astatement that releases are controlled almostentirely by direct releases to the surface ascuttings, cavings, and spallings. DOE shouldcorrect this statement to include cuttings, cavings,and direct brine release, as explained in AppendixPA-2009, Section 9.0.InAppendixPA 2009,Section4.9,pagePA162, line 2, the phrase “cuttings, cavings, andspallings” should be changed to “cuttings,cavings, and direct brine releases”.EPASNL ClaytonRevisedtextincluded in 1stResponseSubmittal to theEPASubmittedtoEPAin 1st ResponseAug 24, 20098 EPA Comment 1-C-10 Chemistry IssuesIn Appendix SOTERM-2009, Section 4.4, DOEstates that the chemical potential (μo/RT) forTh(OH)4(s) was changed in the FMT databasesince the CRA-2004 PA. However, only thechemical potential for Th(OH)4(aq) changedbetween the CRA-2004 PA and the CRA-2004PABC (Xiong et al. 2005). DOE should correct thisstatementThe DOE agrees with this comment – this is atypographical error in the text. The text willbe corrected to read Th(OH)4 (aq). Note thatthis is correctly stated in Figure SOTERM-17and Equation SOTERM. 48.EPA LANL-Reed Revised textincluded in 2ndResponseSubmittal to theEPASubmitted to EPAin 2nd ResponseOct, 2009Page 4 of 11Enclosure 39 EPA Comment 1-C-11In Appendix SOTERM-2009, Section 4.4, DOEshould explain what is meant by their statementthat, "The effects of hydromagnesite and calciteprecipitation were added..." to the FMT database forthe CRA-2004 PABC, because hydromagnesite andcalcite thermodynamic data have been included inthe database at least since the CCA PAVT. Inaddition, SOTERM-4.4 states that the version of thecode used was FMT_050405.CHEMDAT, which isthe database version, not the code. DOE shouldcorrect this misstatement.The EPA is correct in their statement thathydromagnesite and calcite precipitation wereincluded in the FMT calculations at leastsince the time of the CCA PAVT. The secondbullet in SOTERM-2009, Section 4.4 shouldbe replaced with, “The dimensionlessstandard chemical potential for whewellite(CaC2O4•H20) was added to the database(Xiong 2004).”The first sentence in SOTERM-2009, Section4.4 should read, “The version of the databaseused with the FMT code for the CRA-2004PABC was FMT_050405.CHEMDAT (Xiong2005).”These corrections will be added to the erratalist for Appendix SOTERM-2009.EPA LANL-Reed Revised textincluded in 2ndResponseSubmittal to theEPASubmitted to EPAin 2nd ResponseOct, 200910 EPA Comment 1-C-17 Chemistry Issues – ProperReference for Brush (2005) in Section 2.3.2In Appendix SOTERM-2009, Section 2.3.2, Brush etal. (2006) is cited as part of the documentation forthe CRA-2004 PABC, but this report was preparedafter the CRA-2004 PABC. DOE should replace itwith the correct reference (Brush 2005).The DOE agrees with this comment. Brush2005 is the correct reference. This will beadded to the errata list for Appendix SOTERM2009.EPA LANL-Reed Included in 2ndResponseSubmittal to theEPASubmitted to EPAin 2nd ResponseOct, 2009Page 5 of 11Enclosure 311 EPA Comment 1-23-5 Chemistry Issues –Inconsistencies in pH in SOTERMIn Appendix SOTERM-2009, Section 3.3.2 andSOTERM-2009, Section 3.6.2, DOE states that thepcH of the WIPP brines is expected to beapproximately 8.7 or 8.5. Based on FMT modelingperformed for the CRA-2004 PABC, however, thepcH of GWB and ERDA-6 are expected to be 9.39and 9.64, respectively. The pcH values cited byDOE seem to reflect the pH values of 8.69 and8.94. DOE should correct the cited pcH values andreinterpret the solubility data in light of the correctvalues.1) Change the following in AppendixSOTERM Section 3.3.2:“At the expected pCH+ in the WIPP (~8.7),the measured uranium solubility was between10-7 M and 10-6 M.”To:“At the expected pCH+ in the WIPP (~9.5),the measured uranium solubility was between10-7 M and 10-6 M.”2) Change the following in AppendixSOTERM Section 3.6.2:"The WIPP-relevant data summarized in thisreport support current PA calculationsperformed with the use of the Pitzer model(U.S. Department of Energy 2004, AppendixPA, Attachment SOTERM) for the values of 3× 10-7 M and 1.7 × 10-7 M in GWB andERDA-6, respectively, at pCH+~8.5."To:"The WIPP-relevant data summarized in thisreport support current PA calculationsperformed with the use of the Pitzer modelEPA LANL-Reed Included in 3rdResponseSubmittal to theEPASubmitted to EPAin 3rd ResponseNov 2009pe o ed t t e use o t e t e ode(U.S. Department of Energy 2004, AppendixPA, Attachment SOTERM) for the values of 3× 10-7 M and 1.7 × 10-7 M in GWB andERDA-6, respectively, at pCH+~9.5."Page 6 of 11Enclosure 312 EPA Comment 1-C-8 Chemistry Issues – Issue ofpH in microbial and non-microbial vectorsThe fourth paragraph of Appendix SOTERM-2009,Section 2.3.2 states:"the expected pH, when little or no carbonate ispresent, is 8.69 in GWB brine and 8.94 for ERDA-6brine. In both cases, this pH is established/bufferedby the brucite dissolution reaction. The presence ofmicrobial activity will potentially contributesignificant amounts of carbon dioxide and leads toa model-predicted pH of 8.69 and 9.02 for GWBand ERDA-6 brine, respectively.DOE also states that the ERDA-6 pH is 9.02 in thetext immediately following equation SOTERM.4.These statements appear to confuse the results ofFMT modeling for the CRA-2004 PABC and theCRA-2004 PA. The pH values of 8.69 and 8.94 forGWB and ERDA-6 brine, respectively, wereobtained for microbial vectors with organic ligandsfor the CRA-2004 PABC. The pH values of 8.69and 9.02 for GWB and ERDA-6 brine, respectively,were obtained for microbial vectors with organicligands for the CRA-2004 PA. DOE should clarifythis statement, in light of the fact that all vectors forIn Section 2.3.2, Page 10, line 12-16 ofAppendix SOTERM change:“Under these repository-relevant conditions,the expected pH, when little or no carbonateis present, is 8.69 in GWB brine and 8.94 forERDA-6 brine. In both cases, this pH isestablished/buffered by the brucite dissolutionreaction. The presence of microbial activitywill potentially contribute significant amountsof carbon dioxide and leads to a modelpredicted pH of 8.69 and 9.02 for GWB andERDA-6 brine, respectively.”To:“Under these repository-relevant conditions,the model-predicted pH is 8.69 in GWB brineand 8.94 for ERDA-6 brine. In both cases,this pH is established/buffered by the brucitedissolution reaction.”EPA LANL-Reed Included in 3rdResponseSubmittal to theEPASubmitted to EPAin 3rd ResponseNov 2009t s state e t, g t o t e act t at a ecto s othe PABC were assumed to include microbialdegradation of cellulose or cellulose, plastics, andrubberPage 7 of 11Enclosure 3And on page 10, line 36 to page 11 line 2change:“Consideration of the possibility of high CO2levels leads to a calculated pH of 8.69 and9.02 for GWB and ERDA-6 brine,respectively. This is a relatively small changein the predicted pH with no change predictedin GWB brine and only a 0.08 pH shift inERDA-6 brine. These values of fCO2and pHwere used in the actinide speciation andsolubility calculations for all CRA-2004 PABCvectors (Brush 2005).”To:“This value of fCO2and a pH of 8.69 and 8.94for GWB and ERDA-6 brine, respectively,were used in the actinide speciation andsolubility calculations for all CRA-2004 PABCvectors (Brush 2005).”Page 8 of 11Enclosure 313 EPA Comment 1-C-12 Chemistry Issues – Stabilityand likelihood of Pu(III) in BrineIn the caption for Appendix SOTERM-2009, FigureSOTERM-11, DOE states that the Eh-pH diagramdemonstrates that Pu(IV) species would be stableat near-neutral pH. However, at the reducingconditions expected in the repository (near thelower stability limit for water), Pu(III) species appearto be the most stable (PuCO3+ and Pu(CO3)2-).DOE should explain this apparent discrepancy.In Appendix SOTERM, page 51, figure legendfor Figure 11, change:“Speciation Diagram for Plutonium inCarbonated Low-Ionic-Strength Groundwater(Based on Data Presented in Runde et al.2002). This Illustrates the Expected LowerSolubility of Reduced Pu, Shows Pu(IV)Rather Than Pu(III) Species at Near-NeutralpH, and Suggests That the Dominant PuSpecies in the pH 8-9 Range are HydrolyticSpecies with Lesser Contributions FromCarbonate.”To:“Speciation Diagram for Plutonium inCarbonated Low-Ionic-Strength Groundwater(Based on Data Presented in Runde et al.2002). This Illustrates the Expected LowerSolubility of Reduced Pu(III) and Pu(IV), andSuggests That the Dominant Pu Species inthe pH 8-9 Range are Hydrolytic Species withLesser Contributions From Carbonate.”EPA LANL-Reed Included in 3rdResponseSubmittal to theEPASubmitted to EPAin 3rd ResponseNov 2009Page 9 of 11Enclosure 314 EPA Comment 1-C-13 Chemistry Issues – Datarequest for Figure SOTERM-16 and error in FigureDOE should provide the carbonate concentration,total americium concentration, and assumed ionicstrength for generation of Appendix SOTERM-2009,Figure SOTERM-16. In addition, DOE shouldcorrect a typographical error in the figure, where thesubscript "3" was omitted from Am(OH)3(s).The specifics used to generate FigureSOTERM-16 are discussed in more detail inreference Richmann et al. (2008) provided tothe EPA. The concentrations used ingenerating this Figure are the predictedsolubility of III actinides in the CRA-2004PABC for reacted GWB brine.The DOE agrees that the “3” wasinadvertently omitted from Am(OH)3(s) inFigure SOTERM-16.In Appendix SOTERM, page 72, FigureSOTERM-16, change:To:EPA LANL-Reed Included in 3rdResponseSubmittal to theEPASubmitted to EPAin 3rd ResponseNov 2009oPage 10 of 11Enclosure 315 EPA Comment 1-C-14 Chemistry Issues –Inconsistencies in Description of Organic LigandEffectsDOE states in Appendix SOTERM-2009, Section4.6 that organic ligands do not significantly affectactinide solubilities, despite data presented inAppendix SOTERM-2009, Table SOTERM-19showing that ligands increased the calculated +IIIactinide solubilities by factors of 1.71 (GWB) and3.32 (ERDA-6) and +V actinide solubilities byfactors of 1.50 (GWB) and 1.53 (ERDA-6). Thisstatement is also at odds with the assertion inSOTERM-3.7 that EDTA and citrate couldpotentially affect actinide solubilities in WIPPbrines. DOE should correct this statement,especially in light of the data indicating that ligandconcentrations in the inventory have increasedsignificantly since the CRA-2004 PABC.In Appendix SOTERM, Section 4.6, page 79,line 27 change:“The FMT calculations (Brush 2005)demonstrate that the solubility of the III and IVactinides was not significantly enhanced bycomplexation with acetate, citrate, EDTA, andoxalate at their maximum potentialconcentrations (Table SOTERM-19)”.To:“The FMT calculations (Brush 2005)demonstrate that the solubility of the III and IVactinides are only slightly affected by organiccomplexation (Table SOTERM-19). Thesolubility of the III actinides was increased bya factor of 1.7 in GWB and 3.3 in ERDA-6brine. In both brines the solubility of the IVactinides was decreased by organiccomplexation. The overall effect of thesechanges on the release of actinides is notconsidered significant.”EPA LANL-Reed Included in 3rdResponseSubmittal to theEPASubmitted to EPAin 3rd ResponseNov 2009Page 11 of 11