Site 28 Update, Moffett RAB, November 14, 2013

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Site 28 update presentation to the Moffett Restoration Advisory Board, November 14, 2013.

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Site 28 Update, Moffett RAB, November 14, 2013

  1. 1. Former NAS Moffett Field Site 28 Supplemental Investigation RAB Meeting November 14, 2013 Valerie Harris, PE – Navy Remedial Project Manager Neil Hey, PG - CB&I Federal Solutions BRAC PMO West
  2. 2. Presentation Overview  Site Background  Project Objectives  Technical Approach  Building 88 Area - Preliminary Results  Traffic Island Area – Preliminary Results and Additional Planned Work  Questions 2
  3. 3. 3
  4. 4. Treatability Tests  Treatability tests were performed in three areas at Site 28 between July 2010 and June 2011  Analytical results from treatability study wells in the Building 88 Area showed that the shallower “upgradient” well had the highest concentrations of chlorinated ethenes.  Analytical results from observation wells in the Traffic Island Area showed that the deepest treatment area well had the highest concentrations of chlorinated ethenes.  These two areas were targeted for a supplemental investigation after the treatability tests were complete to better define the high concentration areas. 5
  5. 5. Project Objectives Supplemental investigation is needed to: 1) Further delineate PCE & daughter products (TCE, DCE, & VC) in A-aquifer within & around the Former Building 88 & Traffic Island source areas 2) Confirm depth & lateral continuity of A/B-aquitard in Traffic Island Area 3) Verify depth to top of B2-aquifer in Traffic Island Area 4) Confirm whether existing well W88-1, located in the Traffic Island Area, is screened in the B2-aquifer 5) Confirm whether B-aquifer beneath Traffic Island Area is impacted by chemicals of concern above ROD cleanup standards and MCLs (EPA, 1989) 6
  6. 6. Technical Approach Phase 1: • SCAPS  Semi-quantitative COC concentration data (mg/L of calibration solution). Membrane interphase probe (MIP) data are only considered estimates.  Results by MIP system are relative & should be verified by soil and groundwater. Phase 2: • Monitoring Well Installation/Soil Sampling • Groundwater Sampling
  7. 7. Building 88 Area Results Membrane Interphase Probe (MIP) 8
  8. 8. Building 88 Investigation Activities SCAPS Investigation – (Feb 2013 RAB) • • 24 SCAPS tests to 70 feet below ground surface Soil Sampling and Grab Groundwater Sampling • • 9 discrete soil samples and 9 grab groundwater samples Monitoring Well Installation • • 6 groundwater monitoring wells Soil Sampling • • 2 to 3 samples from each well borehole Groundwater Sampling • • 2 rounds of samples collected 9
  9. 9. SCAPS PCE Results – Upper A-aquifer Former Building 88 Area mg/Lcs denotes milligrams per liter 28SI-05 (9 of DSITMS bgs) – 19 ft calibration solution General Groundwater Flow Direction 28SI-03 (10 – 20 ft bgs) ≥500 mg/Lcs - DSITMS >100 mg/Lcs - DSITMS >1 mg/Lcs - DSITMS 28SI-02 (10 – 20 ft bgs) Not Detected 28SI-01 (10 – 20 ft bgs) Maximum MIP/DSITMS Response PCE Upper A-aquifer 10 (6 to 35 ft bgs)
  10. 10. SCAPS PCE Results – Lower A-aquifer Former Building 88 Area General 28SI-04 (39 - 49 ft bgs) Groundwater Flow Direction mg/Lcs denotes milligrams per liter of DSITMS calibration solution 28SI-12 (46 - 51 ft bgs) >100 mg/Lcs - DSITMS ≥1 mg/Lcs - DSITMS Not Detected Maximum MIP/DSITMS Response PCE Lower A-aquifer 11 (35 to ~67 ft bgs)
  11. 11. Groundwater Well Installation Building 88 Area 6 monitoring wells were installed at the Building 88 Area 12
  12. 12. Groundwater – PCE Results Building 88 Area 28SI-03 (10 – 20 ft bgs) PCE =not detected 28SI-05 (9 – 19 ft bgs) PCE = 150 mg/L 28SI-02 (10 – 20 ft bgs) PCE = 35 mg/L 28SI-01 (10 – 20 ft bgs) PCE = 14 mg/L 4 shallow wells – screened ~10 to 20 ft bgs Concentrations not indicative of source area 13
  13. 13. Groundwater – PCE Results Building 88 Area/Lower A 28SI-04 (39 - 49 ft bgs) PCE = 820 mg/L 28SI-12 (46 - 51 ft bgs) PCE = 2,900 mg/L 2 deeper wells – screened 39 to 49 ft bgs & 46 to 51 ft bgs Concentrations higher than shallow wells but we have existing 14 down gradient wells for definition
  14. 14. Traffic Island Area Results 15
  15. 15. Investigation Activities Traffic Island Area SCAPS Investigation • • • 28 SCAPS tests to 100 feet 2 SCAPS tests to 115 feet Monitoring Well Installation • • 6 wells Soil Sampling • • 2 to 3 samples from each well boring Groundwater Sampling • • new wells, two sampling events 16
  16. 16. SCAPS PCE Results – Upper A-aquifer Traffic Island Area mg/Lcs denotes milligrams per liter of DSITMS calibration solution >1,000 mg/Lcs - DSITMS >100 mg/Lcs - DSITMS >5 mg/Lcs 28SI-08 (7 -17 ft bgs) - DSITMS Not Detected Maximum MIP/DSITMS Response General Groundwater Flow Direction 17 PCE Upper A-aquifer (6 to 35 ft bgs)
  17. 17. SCAPS PCE Results – Lower A-aquifer Traffic Island Area mg/Lcs denotes milligrams per liter of DSITMS calibration solution >10,000 mg/Lcs - DSITMS >1,000 mg/Lcs - DSITMS ≥100 mg/Lcs - DSITMS ≥3 28SI-011 (48 -58 ft bgs)mg/Lcs - DSITMS Not Detected Maximum MIP/DSITMS Response General Groundwater Flow Direction 18 PCE Lower A-aquifer (36 to ~78 ft bgs)
  18. 18. SCAPS PCE Results – B2-aquifer Traffic Island Area mg/Lcs denotes milligrams per liter of DSITMS calibration solution >10,000 mg/Lcs - DSITMS >1,000 mg/Lcs - DSITMS >100 mg/Lcs - DSITMS >8 mg/Lcs - DSITMS Not Detected 28SI-10 (90 – 100 ft bgs) 28SI-06 (90 – 100 ft bgs) 28SI-09 (90 – 100 ft bgs) Maximum MIP/DSITMS Response 28SI-07 (105 – 115 ft bgs) General Groundwater Flow Direction 19 PCE B2-aquifer (~78 to 100 ft bgs*) * Two locations to 115 ft bgs
  19. 19. Groundwater Well Installation Traffic Island Area • Wells installed from July 10 to 24, 2013 at locations based on results of the SCAPS • Upper/Lower A-aquifer – One shallow well (screened 7 to 17 ft bgs) – One well screened 48 to 58 feet bgs • B2-aquifer – Three wells screened 90 to 100 feet bgs – One well screened 105 to 115 ft bgs 20
  20. 20. Upper A-aquifer Groundwater Results 28SI-08 (7 -17 ft bgs) PCE = 300 mg/L Well installed to provide information on the shallow groundwater near Building 126 21
  21. 21. Lower A-aquifer Groundwater Results 28SI-011 (48 -58 ft bgs) PCE = 5,300 mg/L • Well installed to provide information about groundwater typical Sudan dye test downgradient of high concentration area • EPA considers PCE >1,000 mg/L to be a “source” • Positive Sudan dye test was at 63 ft bgs in the Lower Aaquifer, but a well was not screened at this depth 22 Soil from 63 feet bgs at 28SI-06 had positive Sudan dye test
  22. 22. Additional Wells in Traffic Island • 3 additional monitoring wells are planned for Lower A-aquifer – 2 collocated wells in down gradient direction • Screen intervals of 32 to 42 feet bgs and 58 to 68 feet bgs • Provide definition of source area – 1 at location of observed DNAPL ganglia • Screen interval from 60 to 65 feet bgs • Installation planned for early December 2013 23
  23. 23. Proposed Additional Traffic Island Wells mg/Lcs denotes milligrams per liter of DSITMS calibration solution >10,000 mg/Lcs - DSITMS >1,000 mg/Lcs - DSITMS 28SI-14 (32 – 42 ft bgs) ≥100 mg/Lcs - DSITMS 28SI-15 (58 – 68 ft bgs) 28SI-011 (48 -58 ft bgs) ≥3 mg/Lcs - DSITMS Not Detected Proposed New Well Newly Installed Well 28SI-13 (60 - 65 ft bgs) General Groundwater Flow Direction 24 Lower A-aquifer (36 to ~78 ft bgs)
  24. 24. A/B-aquitard • SCAPS tests confirmed that predominately fine grained sediments are present at all locations investigated between ~ 75 and 78 ft bgs. • These materials are considered to be the A/B-aquitard • It varies in thickness in the Traffic Island Area from ~3 feet to >10 feet thick. • However poorly graded sand with silt observed in well boring 28SI-07 from 76 to 77.5 ft bgs; and clayey sand in well boring 28SI-10 from 76 to 78 ft bgs • Aquitard may not be laterally continuous 25
  25. 25. B2 Aquifer – Traffic Island • Based on CPT data from 28 SCAPS tests, the B2 aquifer begins about 78 feet bgs (proj obj #2) • Existing deep well W88-1 is screened (72 to 82 ft bgs) across the interval of the lower A-aquifer, A/B-aquitard and top of the B2 aquifer (proj obj #4) • Four new wells installed in the B2 aquifer in predominately fine grained sediments (with thin silty sand layers) – Screened interval 90 to 100 ft bgs: • 28SI-06; 28SI-09;28SI-10 – Screened interval 105 to 115 ft bgs: • 28SI-07
  26. 26. B2 Aquifer – Traffic Island Area 28SI-10: • Groundwater flow to the PCE: 9.5 mg/L north-northwest • High concentration area defined by SCAPS tests with 28SI-09: W88-1: PCE: 2.4 mg/L ND response PCE: 260 mg/L • Low groundwater 28SI-06: concentrations confirmed PCE: 10,000 mg/L near ND response • B-aquifer is impacted by COCs above cleanup PCE Groundwater Results standards (proj obj #5) 85 - 100 ft bgs 27
  27. 27. Results for Monitoring Well 28SI-07 Deepest well installed in Traffic Island Area PCE result from August: 9,500 mg/L Total depth of SCAPS investigation was limited by approved scope MIP response at bottom of hole was 400 mg/Lcalibration solution 28SI-07 PCE: 9,500 mg/L Groundwater Results 100-115 ft bgs 28
  28. 28. Next Steps • Install additional wells in Traffic Island Area • Collect second round of groundwater samples from the 12 newly installed monitoring wells • Prepare Technical Memorandum – Draft Technical Memorandum: May 2014 • Evaluate Path Forward for Treatment 29
  29. 29. Questions? Point of Contact: Scott Anderson BRAC Environmental Coordinator (619) 532-0938 scott.d.anderson@navy.mil 30

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