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Florida Remediation Conference

Florida Remediation Conference Site Remediation Using Horizontal Air Sparge (AS)/ Soil Vapor Extraction (SVE), and Multiphase Extraction (MPE) Wells Narayanan Raghupathi , P.E. (MACTEC) Angela Finney (MACTEC). Country Corner Shell Tallahassee, Florida.

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Florida Remediation Conference

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  1. Florida Remediation Conference Site Remediation Using Horizontal Air Sparge (AS)/ Soil Vapor Extraction (SVE), and Multiphase Extraction (MPE) Wells Narayanan Raghupathi, P.E. (MACTEC) Angela Finney (MACTEC) Country Corner Shell Tallahassee, Florida This paper has been forwarded to you by:

  2. Site Location

  3. Site Map

  4. Site History Active gas station Located at intersection of Hwy 319 and Hwy-27 in Tallahassee, Florida 1986- Approximately 1,000 gallons of premium unleaded gas leaked from an UST Cleanup being conducted under FDEP Preapproval Program (Robert Brown, FDEP Site Manager) 1995- Installed groundwater recovery and AS/SVE systems (Delta, Inc.)

  5. Site Assessment Site Geology consists of sandy clay to clayey sand and grading to fine silty sand at 40 ft bls. Depth to water – 41 feet bls Soil plume – 9,620 square feet (15 to 30 ft bls) Groundwater plume – 46,722 square feet COCs – VOCs, PAHs and TRPH Highest Total BTEX – 11,720 (MW-20R2) Downgradient contamination migration

  6. Baseline Groundwater Plume

  7. Baseline Soil Plume

  8. Remedial Design Challenges Remediating contamination beneath Hwy 319 and Hwy 27 and large downgradient groundwater plume (residential area) Conduct construction activities without closing the store Deep groundwater plume (41 feet bls) Community relations Cleanup goals – SCTLs and GCTLs per 62-777, F.A.C

  9. Remedial Design Downgradient - Install two horizontal AS and SVE wells, 800 feet long w/ 450 feet of screen Upgradient - Install two horizontal AS and SVE wells, 400 feet long w/200 feet of screen Horizontal AS Wells – 48 feet bls Horizontal SVE Wells – 35 feet bls Source – Install vertical AS (15) and MPE (9) wells, and use 15 previously installed MPE wells

  10. Engineering Design Challenges Determining horizontal well layout, screen depths, entry and exit locations Design of horizontal AS and SVE well screens to have even distribution of air flow through the length of the screen Remediate large BTEX and MTBE plume Develop a complete zone of influence Optimal equipment sizing Develop system O&M program

  11. Down gradient Horizontal AS and SVE Well Layout

  12. Upgradient Horizontal AS and SVE Well Layout

  13. Vertical AS and MPE Well Locations

  14. Pressure Along the Screen (psig) in Well HAS-1 OPEN AREA 0.28 % 30.00 29.95 29.90 29.85 29.80 29.75 29.70 0 50 100 150 200 250 300 350 400 Distance Along the Screen (ft) Pressure Drop in Air Sparge Screen Head loss along screen is less than 1%

  15. Injection Rate (SCFM / foot of screen) in Well HAS-1 OPEN AREA 0.28 % 0.8100 0.8050 0.8000 0.7950 0.7900 0 50 100 150 200 250 300 350 400 Distance Along the Screen (ft) Injection Rate in Air Sparge Screen Slot distribution designed to distribute flow

  16. Pressure Along the Screen (psig) in Well HVE-1 - OPEN AREA 0.97 % - 6.20 0 50 100 150 200 250 300 350 400 - 6.30 - 6.40 - 6.50 - 6.60 - 6.70 - 6.80 Distance Along the Screen (ft) Loss of Vacuum in SVE Screen Head loss along screen is less than 5%

  17. Extraction Rate (SCFM / foot of screen) in Well HVE-1 OPEN AREA 0.97 % 1.5200 1.5150 1.5100 1.5050 1.5000 1.4950 1.4900 0 50 100 150 200 250 300 350 400 Distance Along the Screen (ft) Extraction Rate in SVE Screen Screen designed to minimize drop in flow rate

  18. Horizontal Drilling Drilling FluidsManagement • Mud recycler separates sand/silt cuttings from fluid returns • Flowing sands produced high volume of solid returns

  19. Air Sparge Screen Longitudinally slotted 0.27% average open area 1.0” average slot length 0.1” slot width

  20. Soil Vapor Extraction Screen Longitudinally slotted 1.01% average open area 3.7” average slot length 0.1” slot width

  21. Well HAS-1 Pitch Profile Distance in Feet from Entry Point 0 0 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 - 10 - 20 - 30 Vertical Depth in Feet from Ground Surface at Rig - 40 - 50 Markers Denote 4 - inch SDR - 11 HDPE Screen End - of - Rod Locations - 60 Horizontal Air Sparge Well Profile

  22. Well HVE-1 Pitch Profile Distance in Feet from Entry Point 0 0 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 - 10 - 20 Vertical Depth in Feet from Ground Surface at Rig - 30 - 40 4 - inch SDR - 11 HDPE Screen - 50 Markers Denote End - of - Rod Locations - 60 Horizontal SVE Well Profile

  23. AS/SVE and MPE System AS Compressor – 717 scfm @ 30 psi SVE Blower - 2624 acfm @ 14 In. Hg MPE LRP- 2531 acfm @ 16 In. Hg. Air Treatment – Two, 1,600 pound carbon vessels GW Stripper – Air Stripper

  24. AS/SVE and MPE System

  25. System Operation Cycle Vertical AS – 8:00 AM to 8:00 PM HAS1 – 8:00 AM to 2:00 PM HAS-2 – 2:00 PM to 8:00 PM HAS-3 – 8:00 PM to 2:00 AM HAS-4 – 2:00 AM to 8:00 AM MPE wells – 24 hours SVE wells – 24 hours

  26. Cleanup Progress Evaluation

  27. Current Groundwater Plume

  28. Cleanup Summary Target Contaminant concentrations below NAM PAHs below GCTLs BTEX Plume Area – 6,500 sq. ft MTBE Plume Area – 7,000 sq. ft BTEX – 99 percent reduction MTBE – 90 percent reduction

  29. Project Summary Successfully installed horizontal AS and SVE wells (Mike Sequino, Directional Technologies) Horizontal AS/SVE wells are effective in reducing contaminant concentrations. Achieved even air flow through the length of the horizontal well screens. MACTEC Project Manager, Angela Finney, successfully worked with FDEP, property owners, and merchants. Completed project on time and budget.

  30. QUESTIONS

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