H&L Remediation 2011
- 1. In Situ Chemical Reduction of Hexavalent Chromium in Soils and Groundwater Using Ferrous Sulfide (FeS) Nanotechnology Richard H. Christensen, PhD, LPG Indianapolis, IN µg/L Steven R. Irvin Jim V. Rouse (MWH)
- 2. Site Location -- Muncie, IN Source Areas © AcuityES 2011
- 3. Chrome Plating at its best! © AcuityES 2011
- 4. Site Overview Site Conditions First investigation – 2005 A’ AcuityES - 2008 Status: Equipment Deconned Building Demolished FOLLOWING SLIDES - GEOLOGY - HYDROGEOLOGY - REMEDIAL APPROACH - RESULTS A © AcuityES 2011
- 5. Geology FORMER BASEMENT SOURCE AREA © AcuityES 2011
- 6. Hydrogeology Unconfined Aquifer Sands & fine gravels Static Water at 15’ bgl Saturated thickness 5’ in SE to > 25’ in NW © AcuityES 2011
- 7. Soil Impacts Max Cr+6 concentration: 7,900,000 µg/Kg 3,600,000 µg/Kg Cr+6 at 12’ bgl Two Adjacent Source Areas 5,400 cubic yards of impact Perched water sand stringers © AcuityES 2011
- 8. Groundwater Impacts On-Site Cr+6 800,000 µg/L 9,700,000 µg/L Groundwater CoCs 66,000 sq ft Plume Cr+6, Sb, As, and Ni Offsite Cr+6 at 58,800 µg/L © AcuityES 2011
- 9. Selected ISCR for Remediation Enhanced what was already occurring at Site © AcuityES 2011
- 10. Chemical Reductant – FeS BENCH TESTED SELECTED –FeS •Ferrous Sulfide Liquid suspension of 7% FeS •CaSx FeS - With additional 2% free Sulfide to simulate CaSx •Sodium Thiosulfate •Sodium Metabisulfite Nanoscale: 98% crystals <5 microns •Zero Valent Iron Cation (Iron) & Anion (sulfide) Reaction •Organosulfates 4 H2O + Cr04 2-+ 3 Fe2- + 4 OH- 3 Fe(OH)3+ Cr(OH)3 (1) 17 H2O + 8 Cr042- + 3 HS- 3 S + 8 Cr(OH)3 + 12 OH- (2) © AcuityES 2011
- 11. In-Situ Soil Blending GPS Grid Network – 10’ x 10’ Deep to 15’ & Shallow to 5’ Dual Axis Blender – 15’ Plunge Total Area – 130’ x 110’ Computerized Dosing © AcuityES 2011
- 12. In-Situ Soil Blending Dual Axis Blender FeS - 5% admix (15 gals/yd3) © AcuityES 2011
- 13. In-Situ Soil Blending Thorough Mixing to 15’ BGL Note: Cement barrier for uncompaction © AcuityES 2011
- 14. In-Situ Soil Blending Completed in 2 weeks Total FeS = 78,300 gallons Subsequent stabilization with aglime required © AcuityES 2011
- 15. Confirmation Sampling © AcuityES 2011
- 16. Groundwater Injections – FeS THE NUMBERS 155 Inject Pts 15 ft ROI 3% by volume 25 gals / LF 6 wks complete © AcuityES 2011
- 17. Groundwater Injections Difficult Injections Boulder Fields 6’ caliche Lodgement till © AcuityES 2011
- 18. Groundwater Injections FeS Injection Totes 35,385 gallons injected Rotosonic Drilling Top Down Injection – 5ft intervals © AcuityES 2011
- 19. Groundwater Injections Community Sensitivity Required Residential Hours © AcuityES 2011
- 20. Preferential Flow Paths 15 – 20’ bgl Sand Unit © AcuityES 2011
- 21. Preferential Flow Paths 20 - 25’ bgl Sand Unit © AcuityES 2011
- 22. Pre-Treatment Cr +6 © AcuityES 2011
- 23. 1 st Q Post-Treatment Cr +6 © AcuityES 2011
- 24. 2 nd Q Post-Treatment Cr+6 © AcuityES 2011
- 25. 3 rd Q Post-Treatment Cr +6 © AcuityES 2011
- 26. On-Site Monitoring Wells - Cr+6 © AcuityES 2011
- 27. Off-Site Monitoring Wells - Cr+6 © AcuityES 2011
- 28. Summary of Cr+6 Reduction © AcuityES 2011
- 29. Pre-Treatment Antimony © AcuityES 2011
- 30. 1 st Q Post-Treatment Antimony © AcuityES 2011
- 31. 2 nd Q Post-Treatment Antimony © AcuityES 2011
- 32. 3 rd Q Post-Treatment Antimony © AcuityES 2011
- 33. Other Constituents of Concern Nickel – off-Site up to 4,100 µg/L on-Site up to 50,000 µg/L Same footprint as Antimony Complete 100% Reduction by 1st Quarter Arsenic – Overall reduction in pervasiveness. Occurrence generally coincides with Cr+6 © AcuityES 2011
- 34. Lessons Learned 1. Forced to use Rotosonic over direct push - Budget for the unexpected 2. Chemical injection instead of GW recirculation - Can’t wear blinders when considering delivery method options for chemicals 3. Agency onboard for the technology - Relationship, communication, education © AcuityES 2011
- 35. QUESTIONS? Thank you!! © AcuityES 2011