by Department of Toxic Substances Control Deborah Raphael, Director Matthew ROdff?uEI Cal Center Drive Edmund G. Brown Jr. Secreta for . . Sacramento, California 95826-3200 warm December 2, 2013 Mr. Michael Bower The Boeing Company 5800 Woolsey Canyon Road MC T-487 Canoga Park, California 91304-1148 SOIL CHARACTERIZATION LEVELS FOR THE BOEING RFI SUBAREAS, SANTA SUSANA FIELD LABORATORY, VENTURA COUNTY, CA Dear Mr. Bower: The Department of Toxic Substances Control (DTSC) has reviewed the Boeing Company?s (Boeing) letter of October 28, 2013 (attached) requesting approval to revise the soil characterization levels (SC Ls) for sixteen analytes being evaluated at Boeing sites at the Santa Susana Field Laboratory (SSFL). The SCLs for Boeing sites at SSFL were originally submitted in Table B-1 in Appendix (Table B-1) of the approved Final Master Data Gap Work Plan for SSFL, (MWH, March 2013). An updated Table B-1.is attached to the October 28, 2013 Boeing letter. The revisions to sixteen SCLs are necessary because multiple laboratories cannot routinely achieve the risk-based SCLs approved in the March 2013. Based on review, this letter serves as approval of the updated SCLs in the revised Table B-1 used in developing data gap sampling and analysis plans for Boeing?s RFI Program. Mr. Michael Bower December 2, 2013 Page 2 If you have any questions, please contact me via e-mail at Roqer.Paulson?dtsocaqov or (916) 255-3702. Roger N. aulson, PE Senior Engineer Department of Toxic Substances Control Sincerely, cc: (via e-mail) David Dassler The Boeing Company David.w.dassler@boeinq.com Mark Malinowski Department of Toxic Substances Control Mark.Malinowski?dtsocaqov Richard Hume Department of Toxic Substances Control Donald Greenlee Department of Toxic Substances Control Brian Faulkner Department of Toxic Substances Control Brian.Faulkner@dtsc.ca.gov The Boeing Company Santa Susana Field Laboratory 5800 Woolsey Canyon Road Canoga Park, CA 9604?1148 Via FedEx September 13, 2013 In reply, refer to Mr. Mark Malinowski, PG DTSC Program Manager California Department of Toxic Substances Control 8800 Cal Center Drive Sacramento, CA 95826-3200 Dear Mr. Malinowski: Subject: Submittal of Revised Soil Characterization Levels for Boeing RCRA Facility Investigation, Santa Susana Field Laboratory The Boeing Company (Boeing) herby submits two enclosures that present revised soil characterization levels (SCLs) for the Boeing RCRA Facility investigation (RFI) being conducted at Santa Susana. Boeing requests approval of the SCLs presented in revised Appendix of the DTSC-approved March 2013 Final Master RFI Data Gap Work Plan. ln this appendix, 16 SCLs were revised because multiple laboratories cannot routinely achieve the risk-based SCLs approved for these chemicals in the March 2013 document. The attachments include a revised Appendix B, and Table 1, which presents information for each of these SCLs, and the basis for revising their values as shown. If you have any questions regarding this submittal, please contact Michael Bower at (818) 466?8776. certify under penalty of law that these documents and all attachments were prepared under my direction or supervision in accordance with a system designed to assure that qualified personnel properly gather and evaluate the information submitted. Based on my inquiry of the person or persons who manage the system, or those persons directly responsible for gathering the information, the information submitted is, to the best of my knowledge and belief, true, accurate, and complete. I am aware that there are significant penalties for submitting false information, including the possibility of fine and imprisonment for knowing violations. Dave Dassler, PE Project Director, Santa Susana Field Laboratory Sincerely, Enclosure: Revision of Appendix Revised table of SCLs for Boeing Master 06 Work Plan cc: Roger Paulson, DTSC Dixie Hambrick, MWH Alexa Stamets, CH2M HILL Table 1 Revised Soil Characterization Levels (SCLs) for Boeing Master Data Gap Work Plan Santa Susana Field Laboratory Analyte CAS Number Boeing Combined Strata Suburban Residential (no BTV UTL95-95 (mg/kg) Garden) RBSL (mg/kg) Low TRV Ecological RBSL (mg/kg) Boeing Soil Characterization Level March 2013 (mg/kg) Boeing QAPP Reporting Limits (mg/kg) Background QAPP (mg/kg) Multi-Lab MRLs (mg/kg) Revised Boeing Soil Characterization Level August 2013 (mg/kg) Metals Antimony Selenium 7440360 7782492 0.497 0.536 26.4 380 0.042 0.1 0.497 0.536 1 1 0.2 0.4 0.5 1 0.5 1 Cyanide Cyanides 57125 0.267 1,520 0.18 0.267 0.5 0.5 0.5 0.5 Energetic Constituents 2,4,6-Trinitrotoluene 2-Amino-4,6-dinitrotoluene 118967 35572782 --- 20.7 154 0.13 0.000043 0.13 0.000043 0.4 0.4 --- 0.3 0.3 0.3 0.3 Volatile Organic Compounds 2-Chloroethylvinyl ether Monomethylhydrazine 110758 60344 --- 0.0042 0.00124 160 0.35 0.0042 0.00124 0.01 0.025 --- 0.01 0.025 0.01 0.025 Pesticides Heptachlor epoxide 1024573 0.00011 0.107 0.0013 0.0013 0.0017 0.000166 0.0017 0.0017 Herbicides 2,4-DP (Dichloroprop) MCPP MCPA 120365 93652 94746 0.00142 0.202 0.398 -68.6 34.3 -2.5 0.12 0.00142 2.5 0.398 0.04 6.5 6.5 0.0017 0.25 0.25 0.04 3.3 3.3 0.04 3.3 3.3 Polychlorinated Biphenyls (PCBs) PCB TEQ 1746016-PCB TEQ -- 0.00000357 -- PCB_TEQ_Bird (Coplanar PCBs) 1746016-PCB TEQ_Bird -- -- 0.0000057 PCB_TEQ_Mammal (Coplanar PCBs) Aroclor 1248 Aroclor 5460 1746016-PCB TEQ_Mammal 12672296 11126424 ---- -0.232 0.232 0.0000005 0.0064 0.039 0.00188 a 0.00005 -- -- 0.00005 0.00188 a 0.00005 -- -- 0.00005 0.00188 0.0064 0.039 a 0.00005 0.017 0.05 ---- -0.017 0.05 0.00005 0.017 0.05 Notes: This table presents a list of chemicals that have Boeing Soil Characterization Levels (SCLs) that were approved by DTSC in the Master Data Gap Work Plan (CH2M HILL, 2013) that are less than laboratory MRLs, such that achievement of the RBSL-based SCL is technically limited and/or infeasible. In these cases, a revised Boeing SCL has been identified equal to a low MRL achievable by multiple laboratories. In some cases, the Multi-Lab MRL is slightly less than the Boeing QAPP MRL value, but is recommended for use since it is lower. The following 3 chemicals are not included on this list for revised Boeing SCLs since the Multi-Lab MRL is less than the Boeing QAPP MRL, such that the Boeing SCL is achievable: > Zirconium (mg/kg): SCL =10.64, Boeing QAPP MRL = 25, and Multi-Lab MRL =5 > RDX (mg/kg): SCL = 0.3, Boeing QAPP MRL = 0.4, and Multi-Lab MRL = 0.3 > Hexachlorobutadiene (mg/kg): SCL = 0.022, Boeing QAPP MRL = 0.17, and Multi-Lab MRL = 0.005 (by USEPA method 8260) a - the March 2013 SCL for PCB TEQ values was in error resulting from a data entry error in the table. The March 2013 screening values should have been based on the RBSL values provided above. However, these RBSLs are also less than the Boeing QAPP MRLs for these compounds, and as such, are being rev to the PCB congener MRLs in the Boeing QAPP. The PCB congener MRLs do vary slightly by congener, but all are above the RBSLs. The most common MRL (which is also the MRL of the most toxic congener, PCB 126) is provided above as the PCB TEQ SCL. For characterization, analytical requirements for PCB congeners are those in the Boeing QAPP, the revised SCL will only be used for TEQ screening purposes. UTL 95-95 BTV - for combined strata as presented in Table 5 SSFL Chemical Soil Background Study, Chemical Analytes - Summary of Statistical Evaluation Results as published in DTSC's Final Chemical Background Study Report (Dec 2012); and, DTSC table 'Background Threshold Values Using Combined Chemical Background Data' as published in 'Combined-Data Background Thresholds Values and Methodology Narrative' (Dec 2012). If a BTV was not assigned by DTSC, the maximum reported RL in the background dataset was used. Suburban Residential RBSL (w/o Garden) - Lowest Suburban Residential Soil RBSL without garden pathway; from tab 'Att2a_Tb1_Total RME RBSLs' in HH RBSLs Workbooks _2 submitted to DTSC in November 2012. Eco RBSL (Low TRV) - Lowest 'Low TRV' Soil RBSL; from tab 'Table 12-1_RBSL_Summary' in Nov 2012 EcoRBSL Workbook, submitted to DTSC November 2012. The Boeing Soil Characterization Level is the lowest of the Human Health Suburban Residential RBSL or the Ecological Low TRV RBSL, unless that value is below the Boeing BTV. In cases where the lowest RBSL is less than the Boeing BTV, the Boeing BTV is used as the Soil Characterization Level. Values listed above from Master RCRA Facility Investigation Data Gap Work Plan (CH2M Hill, 2013). Boeing QAPP Reporting Limits from QUALITY ASSURANCE PROJECT PLAN, SANTA SUSANA FIELD LABORATORY (SSFL), RCRA FACILITY INVESTIGATION SURFICIAL MEDIA OPERABLE UNIT, March 2013, Revision 5, Table 4-3, Soil Reporting Limits. BG QAPP RL - Background QAPP MRL values from DTSC 'Revised_QAPP_(Final_June_2011)' - Table 4, ANALYTICAL METHODS AND REPORTING LIMITS (Soil). Multi Lab Method Reporting Limits 04092013_draft final, Draft to DTSC April 09, 2013. Recommended Revised Boeing Soil Characterization level is the lower of the Boeing QAPP Reporting Limits and the Multi-Lab MRL based on the above MRL and RBSL information. Acronyms: BTV - Background Threshold Value CAS Number - Chemical Abstracts Service registry number . Low TRV - Lowest Low toxicity reference value (TRV)-based RBSLs for soil are selected from the EcoRBSLs for upper trophic level receptors. QAPP - Quality Assurance Project Plan RBSL - Risk Based Screening Level UTL - upper tolerance limit Revised SCLs for Boeing Master DG Work Plan 081513 Units: mg/kg - milligram per kilogram 1 of 1 8/16/2013 Table  B‐1 Soil Characterization Levels Master RCRA Facility Investigation Data Gap Work Plan, Santa Susana Field Laboratory, Ventura County, California Analysis Group Dioxin_Furans Dioxin_Furans Dioxin_Furans Energetics Energetics Energetics Energetics Energetics Energetics Herbicides Herbicides Herbicides Herbicides Herbicides Herbicides Herbicides Herbicides Herbicides Herbicides Hydrocarbons Hydrocarbons Inorganics Inorganics Inorganics Inorganics Inorganics Inorganics Metals Metals Metals Metals Metals Metals Metals Metals Metals Metals Metals Metals Metals Metals Metals Metals Metals Metals Metals Metals Metals Metals Metals Metals Metals Metals Metals Metals Metals Analyte 2,3,7,8‐TCDD TEQ DioxinFuran_TEQ_Bird DioxinFuran_TEQ_Mammal 1,2‐Dinitrobenzene 1,3‐Dinitrobenzene 1 2,4,6‐Trinitrotoluene 1 2‐Amino‐4,6‐dinitrotoluene HMX RDX 2,4,5‐T 2,4,5‐Trichlorophenoxypropionic acid 2,4‐Dichlorophenoxyacetic Acid (2,4‐D) 2,4‐Dichlorophenoxybutyric acid Dalapon Dicamba 1 Dichlorprop Dinoseb 1 MCPA 1 MCPP Diethylene Glycol Triethylene glycol Acetic Acid 1 Cyanides Fluoride Nitrate Orthophosphate – PO4 Perchlorate Aluminum 1 Antimony Arsenic Barium Beryllium Boron Cadmium Chromium Cobalt Copper Hexavalent Chromium Lead Lithium Manganese Mercury Methyl Mercury Molybdenum Nickel Potassium 1 Selenium Silver Sodium Strontium Thallium Tin Titanium Vanadium Zinc Zirconium CAS Number 1746016‐TEQ 1746016‐TEQ_Bird 1746016‐TEQ_Mammal 528290 99650 118967 35572782 2691410 121824 93765 93721 94757 94826 75990 1918009 120365 88857 94746 93652 111466 112276 64197 57125 16984488 NO3N 14265442 14797730 7429905 7440360 7440382 7440393 7440417 7440428 7440439 7440473 7440484 7440508 18540299 7439921 7439932 7439965 7439976 22967926 7439987 7440020 7440097 7782492 7440224 7440235 7440246 7440280 7440315 7440326 7440622 7440666 7440677 Page 1 of 4 Soil Characterization Level 0.00000481 0.0000057 0.000000563 0.92 0.92 0.3 0.3 110 0.3 4.8 0.55 1.1 6.2 39 14 0.04 0.18 3.3 3.3 6110 2750 410 0.5 35 2340 863.2 0.5 37900 0.5 24.2 203.8 4.8 22 0.435 60.11 26.18 42 1.29 33.9 64.4 723 0.87 0.18 1.642 64.2 7524 1 0.99 754 1210 0.761 31 1865 111.8 153 10.64 Unit mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg Table  B‐1 Soil Characterization Levels Master RCRA Facility Investigation Data Gap Work Plan, Santa Susana Field Laboratory, Ventura County, California Analysis Group PCBs PCBs PCBs PCBs PCBs PCBs PCBs PCBs PCBs PCBs PCBs Pesticides Pesticides Pesticides Pesticides Pesticides Pesticides Pesticides Pesticides Pesticides Pesticides Pesticides Pesticides Pesticides Pesticides Pesticides Pesticides Pesticides Pesticides Pesticides Pesticides Pesticides Pesticides SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs Analyte Aroclor 1016 Aroclor 1221 Aroclor 1232 Aroclor 1242 1 Aroclor 1248 Aroclor 1254 Aroclor 1260 1 Aroclor 5460 2 PCB TEQ 2 PCB_TEQ_Bird 2 PCB_TEQ_Mammal 4,4'‐DDD 4,4'‐DDE 4,4'‐DDT Aldrin alpha‐BHC beta‐BHC Chlordane Chlordane (Technical) delta‐BHC Dieldrin Endosulfan I Endosulfan II Endosulfan sulfate Endrin Endrin aldehyde Endrin ketone gamma‐BHC Heptachlor 1 Heptachlor epoxide Mirex p,p'‐Methoxychlor Toxaphene 1,1‐Dimethylhydrazine 1,2,4‐Trichlorobenzene 1‐Methyl naphthalene 2,4,5‐Trichlorophenol 2,4,6‐Trichlorophenol 2,4‐Dimethylphenol 2‐Methylnaphthalene 3,5‐Dimethylphenol 4‐Nitrophenol Acenaphthene Acenaphthylene Anthracene Benzo(a)anthracene Benzo(a)pyrene Benzo(b)fluoranthene Benzo(e)pyrene Benzo(ghi)perylene Benzo(k)fluoranthene Benzoic acid Benzyl alcohol bis(2‐Ethylhexyl) phthalate Butyl benzyl phthalate Carbazole CAS Number 12674112 11104282 11141165 53469219 12672296 11097691 11096825 11126424 1746016‐PCB TEQ 1746016‐PCB TEQ_Bird 1746016‐PCB TEQ_Mammal 72548 72559 50293 309002 319846 319857 57749 12789036 319868 60571 959988 33213659 1031078 72208 7421934 53494705 58899 76448 1024573 2385855 72435 8001352 57147 120821 90120 95954 88062 105679 91576 108689 100027 83329 208968 120127 56553 50328 205992 192972 191242 207089 65850 100516 117817 85687 86748 Page 2 of 4 Soil Characterization Level 0.12 0.18 0.082 0.043 0.017 0.039 0.025 0.05 0.00005 0.00005 0.00005 0.0051 0.004164 0.006101 0.0348 0.073 0.394 1.1 1.1 0.067 0.013 0.22 0.22 0.23 0.0079 0.0092 0.0086 0.075 0.087 0.0017 0.0328 2.5 0.493 0.35 10 7.29 75 7.43 65 53 2.6 8 3.1 0.33 2.8 0.387 0.0387 0.387 4.4 4.1 0.387 4.5 4.5 0.32 90 1.5 Unit mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg Table  B‐1 Soil Characterization Levels Master RCRA Facility Investigation Data Gap Work Plan, Santa Susana Field Laboratory, Ventura County, California Analysis Group SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs SVOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs Analyte Chrysene Dibenzo(a,h)anthracene Dibenzofuran Diethyl phthalate Dimethyl phthalate Di‐n‐butyl phthalate Di‐n‐octyl phthalate Fluoranthene Fluorene Hexachlorobutadiene Hexachlorocyclopentadiene Hydrazine   Indeno(1,2,3‐cd)pyrene m‐Cresol 1 Monomethylhydrazine m‐Terphenyl Naphthalene n‐Nitrosodimethylamine n‐Nitrosodiphenylamine o‐Cresol o‐Terphenyl p‐Chloro‐m‐cresol p‐Cresol Pentachlorophenol Perylene Phenanthrene Phenol p‐Nitroaniline p‐Terphenyl Pyrene Tetralin 1,1,1,2‐Tetrachloroethane 1,1,1‐Trichloroethane 1,1,2,2‐Tetrachloroethane 1,1,2‐Trichloro‐1,2,2‐trifluoroethane 1,1,2‐Trichloroethane 1,1‐Dichloroethane 1,1‐Dichloroethene 1,2,3‐Trichlorobenzene 1,2,4‐Trimethylbenzene 1,2‐Dibromo‐3‐chloropropane 1,2‐Dibromoethane 1,2‐Dichlorobenzene 1,2‐Dichloroethane 1,2‐Dichloroethene 1,2‐Dichloropropane 1,3,5‐Trimethylbenzene 1,3‐Dichlorobenzene 1,4‐Dichlorobenzene 1,4‐Dioxane 1 2‐Chloroethylvinyl ether 2‐Hexanone Acetone Benzene Bromobenzene Bromodichloromethane CAS Number 218019 53703 132649 84662 131113 84742 117840 206440 86737 87683 77474 302012 193395 108394 60344 92068 91203 62759 86306 95487 84151 59507 106445 87865 198550 85018 108952 100016 92944 129000 119642 630206 71556 79345 76131 79005 75343 75354 87616 95636 96128 106934 95501 107062 540590 78875 108678 541731 106467 123911 110758 591786 67641 71432 108861 75274 Page 3 of 4 Soil Characterization Level 1.2 0.113 1.2 2.3 4.5 0.11 13 54 1.9 0.022 3 0.173 0.387 5.1 0.025 0.67 14.6 0.0325 2.3 4.3 0.67 1.7 4.3 2.8 10 1.3 5.1 3.4 0.54 1.2 8.29 2.87 2460 0.288 220 0.533 1.89 6.9 10 3.1 0.0978 0.104 130 0.261 96.9 0.439 3.2 23 1.33 2.3 0.01 23 46 0.115 25 0.195 Unit mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg Table  B‐1 Soil Characterization Levels Master RCRA Facility Investigation Data Gap Work Plan, Santa Susana Field Laboratory, Ventura County, California Analysis Group VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs VOCs Analyte Bromoform Bromomethane Carbon disulfide Carbon tetrachloride Chlorobenzene Chloroform Chloromethane cis‐1,2‐Dichloroethene cis‐1,3‐Dichloropropene Cumene Dibromochloromethane Dibromomethane Dichlorodifluoromethane Ethylbenzene Formaldehyde Methyl ethyl ketone Methyl isobutyl ketone (MIBK) Methylene chloride m‐Xylene & p‐Xylene n‐Butylbenzene n‐Propylbenzene o‐Chlorotoluene o‐Xylene  p‐Chlorotoluene p‐Cymene sec‐Butylbenzene Styrene tert‐Butylbenzene Tetrachloroethene Toluene trans‐1,2‐Dichloroethene Trichloroethene Trichlorofluoromethane Vinyl chloride Xylenes, Total CAS Number 75252 74839 75150 56235 108907 67663 74873 156592 10061015 98828 124481 74953 75718 100414 50000 78933 108101 75092 179601231 104518 103651 95498 95476 106434 99876 135988 100425 98066 127184 108883 156605 79016 75694 75014 1330207 Soil Characterization Level 23 3.2 51 0.071 21 0.733 3.2 9.22 9.6 1.3 7.28 22.3 41 2.31 43 8160 4.5 2.97 3.3 61 73 16 3.4 16 3.7 0.98 210 1.1 0.416 59 85.3 0.797 170 0.0204 3.4 Unit mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg Notes:  These characterization levels apply to the Boeing RFI subareas. The Master RFI Data Gap Work Plan addenda for Boeing RFI Subareas 5/9 South and 5/9 North were in  development prior to finalization of these characterization levels. Consequently, the characterization levels used in the Master RFI Data Gap Work Plan addenda for Boeing RFI  Subareas 5/9 South and 5/9 North are the 2005 background levels, the Suburban Residential RBSLs included in the May 2012 Gold Copy hard drive deliverable, and the Low‐TRV  based Ecological RBSLs for soil included in the May 2012 Gold Copy hard drive deliverable. The characterization levels presented in this table will be used in future evaluations of  data gaps for Boeing RFI Subareas 5/9 South and 5/9 North, in accordance with the comprehensive DQO process. 1. The Soil Characterization Levels for these analytes were updated in August 2013 and represent the Method Reporting Limits (MRLs) that can be obtained by multiple analytical  laboratories. The Soil Characterization Levels previously identified for these chemicals were less than the MRLs, such that achievement of the previous Soil Characterization  Levels was technically limited and/or infeasible.  2. The PCB TEQ Soil Characterization Levels were previously set to a background value of 0.00188 mg/kg; however, background values do not exist for PCB TEQs. The risk‐based  screening levels for PCB TEQs are less than levels that can be technically achieved by analytical laboratories. Consequently, the Soil Characterization Levels for PCB TEQs were  updated in August 2013 to represent the MRLs that can be obtained by multiple analytical laboratories.  Page 4 of 4