Santa Susana Field Laboratory RCRA Facility Investigation Report Group 10 Southern Undeveloped Area

Transcription

1 Santa Susana Field Laboratory RCRA Facility Investigation Report Group 10 Southern Undeveloped Area Chatsworth August 3, 2009 Doug Sheeks, R.G. Engineering Geologist DTSC, Sacramento 1

2 But First CERCLA = Comprehensive Environmental Response, Compensation, and Liability Act RCRA = Resource Conservation & Recovery Act RFI = RCRA Facility Investigation RBSLs = risk-based screening levels (1 in a million) NPDES = National Pollutant Discharge Elimination System (Outfalls 001 and 002) VOCs = volatile organic compounds (solvents e.g., TCE) SVOCs = semi-volatile organic compounds TPH = total petroleum hydrocarbons (petroleum products) HH = human health; Eco = ecological SMOU = Surficial Media Operable Unit SRAM = Standardized Risk Assessment Methodology Workplan ND = not detected PCBs = poly-chlorinated byphenyls PAH = Poly-nuclear aromatic hydrocarbons SB990 = Senate Bill 990 TEQ = toxicity equivalency quotient (dioxins) 2

3 And Second DTSC s s review in early stages review continues (Paul s s slide) comments are being prepared estimated review completion - Fall 2009 Still in the works are: SB990-compliant risk assessments, with Agricultural Residential RBSLs Updated, comprehensive background dataset for select chemicals Refined laboratory detection and reporting limits for chemical constituents RFI and background Thus, the data comparisons are temporary. 3

4 Group 10 RFI Report Available on DTSC-SSFL website: (this presentation will also be posted) Ninth submittal to date 11 RFI Group Reports cover the SSFL Important Companions for Review SMOU RFI Program Report (2004) Group 10 SAP (2008) Soil Background Report (2005) - SRAM App. D Public comment period ends August 31, 2009 Public comments are welcome & vital address: dsheeks1@dtsc.ca.gov 4

5 Presentation Topics Group 10 Description, History, Conditions RFI Strategy Group 10 Review Scope Group 10 Investigations Summary RFI Findings & Recommendations DTSC Preliminary Conclusions & Remaining Issues 5

6 SSFL RFI Groups 6

7 Group 10 Description, History, Conditions ~ 790 Acres, south of SSFL & Set Back Boundary established to define area free of chemical impacts & suitable for unrestricted land use Acquired in 1968 Open, Non-developed Land Historically used for cattle grazing Property improvements limited to: Access roads (2 main, mostly non-paved) NPDES outfalls (001 & 002) Above-ground domestic water storage tanks (water via local purveyor - not from SSFL sources) Antenna station No RFI Sites Present No Operational Areas 7

8 Group 10 Investigation Areas Drainages / Watersheds Western, Central, Eastern (also, Exposure Areas) Only Western and Central Drainages receive(d) runoff from SSFL operational areas Seeps & Springs: 2 north; 5 south (2 outside) Group-Wide Surface Soil (RFI: metals & dioxins) Previous VOC-Detection Area Antenna Area Seven Debris Areas DTSC/Public Interest Area (Groundwater is under separate program data summarized in report and discussed in Appendix B) 8

9 Group 10 Investigation Areas 9

10 GW Wells; Seeps/Springs 10

11 RFI Strategy Conduct Chemical Assessments Previous Chemical Detections (follow-up/step-out sampling) Current RFI Conduct HH & Eco Risk Assessments Residential & Recreational HH Scenarios Previous Sampling plus Current RFI data Conduct radiological survey (Groups I, II, III, & Southern Undeveloped Area) including historical site assessment (HSA) DTSC requirement 11

12 Group 10 RFI Report Review Scope Historical research air photos ( ); other documentation critical to the review and consideration of data Potential sources and pathways Site surveys: physical and debris Sample distributions and targeting Analytical results Data gaps records; sampling; analytes; screening levels What still needs to be done? 12

13 Sample Locations Gridding not unique to Grp. 10, but an important difference. Also intended to address possible air dispersion ft soil grid ~500-ft drainage Background Targeted Surface water 13

14 Group 10 Investigations Previous (1993; 1998; 2005 background study) RFI initial & confirmation (2006) Additional RFI & supplemental (2007 & 2008) Seeps / Springs (2009) - results pending 14

15 Analytical Suites (Soils) VOCs SVOCs TPH Pesticides PCBs PAHs Metals Dioxins Inorganics Energetics/Explosives Perchlorate n-nitrosodimethylamine (NDMA) 15

16 Analytical Suites (Surface Water) *Outfalls 001 & 002: Seeps/Springs: VOCs VOCs (2002, 2006, 2007, 2008) Metals Metals (2002, 2004, 2005) Inorganics Inorganics ( 02, 04, 05, 06) Oil & Grease Perchlorate (2002, 2006) Dioxins Radiologic (southern) - in 02 BOD Turbidity/Coliform SVOCs (*Under separate, NPDES Program Regional Board) 16

17 Results Summary Tables (Vol. 1; 3-2A) 17

18 Sample Locations 18

19 Previous VOC Detect Area No VOCs, SVOCs, Energetics detected >RBSLs in follow-up sampling (2008) Benzene (6/93) in soil 0.05 mg/kg: >HH RBSL ( / 110) Low TPH-g (1.73) Cd (2.0)-1993 Cr6 (0.323)-2008 were >RBSLs (1.1 / -) (39 / ) (110 / 0.2) TCE in soil vapor ug/l: >RBSLs ( / 3) 3.822: >RBSLs 19

20 Western Drainage One TPH-g 1.85 mg/kg >HH RBSL (1.1) Low (<HH RBSLs) VOCs, SVOCs, PCBs DDE/DTT <Eco RBSL (0.012) One dioxin 4.5 pg/g: >background (0.87); >Eco RBSL (4.3) Metals <background; >Eco RBSLs (incl. As) Arsenic >HH RBSL (0.095 mg/kg); <background (15) No organic RFI confirmations >background or >RBSLs 20

21 PCB >Eco RBSL (0.0114) - 1 loc.; ND in split & confirmation Dioxins >Bkg & RBSLs -(1 loc.) Molyb >Bkg & Eco RBSL (0.11) - 1 loc. & duplicate Low (<RBSLs) VOCs, SVOCs, & Pesticides (0.012 mg/kg) TPH-g (1.28) >HH RBSL (1.1) - 1 loc. Central Drainage 21

22 Eastern Drainage No RFI drainage samples 22

23 Seeps/Springs Northern Group 10 set: No VOCs Southern Group 10 set: Low VOCs (??- lab QC) - NDs in

24 Group-Wide Surface Soil Sampling Dioxins <Background; <RBSLs Arsenic >Background (15); >HH (0.095) & Eco RBSLs (1.9) 1 location in 1998; 1 location in 2008 RFI (SE corner) Metals >Background & >Eco RBSLs (# of locations) Nickel (2) Cadmium (1) Copper (1) Barium (2) Vanadium (1) Boron (1) Zinc (2) Molybdenum (1) Selen (1) Manganese (1) Nickel (2) Silver (1) Vanadium (1) Zinc (3) Values generally within 10-20% of background 24

25 Debris Areas Debris areas identified in Group 10: empty 55-gallon drum (Central Drainage) seven soil-debris piles (Central Drainage) drums and other debris (Central Drainage) soil-debris pile (Central Drainage) Steel Tank (Western Drainage) 2041 possible soil pile & steel cable (Eastern Drainage) Bricks (Central Drainage) Survey in 2008; 50-foot transect spacing & in drainages All debris removed VOCs (soil), SVOCs, TPH, metals Debris Area 2006 some metals exceeded background and/or RBSLs No background or RBSL exceedances (initial and/or following removals) Group 10 Debris Survey details and photos in Appendix C 25

26 DTSC / Public Interest Area Brought to DTSC s attention by member of public air photo review evidence of roads (fire); vegetation/surface disturbance Fieldwork in August 2008 shallow soil samples (hand auger) DTSC oversight & split samples to separate lab Analyses: VOCs, PAHs, TPH, metals All analytes <background & <RBSLs 26

27 Antenna Station Shallow soil sampling at 1 location auger 2.5 feet Tests for: TPH, freon, PCBs (based on former equip.) metals, VOCs, SVOCs organics not detected at or above detection limits Metals >background and/or >RBSLs Barium (~ 3 times background 140 mg/kg) Aluminum and Vanadium >background & Eco- RBSLs (10-20% of background) Confirmation/Step-out Results (4 locations) Barium <background 27

28 RISK ASSESSMENTS (Appendix A) A Appendix A includes both Human Health and Ecological Risk Assessments Pre-SB990 Risk-Based Screening Levels (RBSLs) were used in report conclusions and recommendations DTSC has temporarily suspended reviews of RFI risk assessments 28

29 Group 10 RFI Report Recommendations Surficial media recommended for no further action with respect to chemicals Based on current risk assessment methodologies and receptors; RBSLs; and background Revise report, as needed, pending: Evaluation of SB990 requirements Site-wide Groundwater Report and large homerange receptor evaluation 29

30 Preliminary DTSC Findings DTSC does not concur with RBSL-based NFA DTSC agrees with need to revise report based on: SB990-compliant criteria Updated background dataset Site-wide Groundwater Report Large home-range receptor evaluation DTSC comments Subsequent re-assessment for need to fill data gaps 30

31 Q&A / Discussion 31