Green Aspects of Aquifer Flushing for Rapid Free Product

5/7/2012

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Presentation to:OKLAHOMA BROWNFIELDS

2012 Conference

Green Aspects of Aquifer Flushing for Rapid Free Product Remediation

Presentation Outline

Surfactant Enhanced Aquifer Flushing (SEAF) Green Technology HighlightsHistory of Aquifer Flushing RemediationSelected Case Studies

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• SEAF is primarily a source removal technique.• Effective for a wide range of subsurface contaminants.• LNAPLs: Gasoline, diesel, crude, fuel and lube oils.• DNAPLs: Chlorinated solvents, coal tars.• Proven results on warranted remediation projects.• Significant time savings over other in-situ remediation technologies.• Food-grade surfactants and formulations.• Low to No discharge, haul-away, or disposal.• Can be combined with other remedial technologies to achieve dissolved contaminant reduction.

Surfactant Enhanced Aquifer Flushing (SEAF) Technology Highlights

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• Surfactants are chemical agents that alter interfacial properties in solutions.• SEAF utilizes surfactant to remove NAPL through solubilization and/or mobilization.• Solubilization of NAPL is accomplished by selecting surfactants that increase the solubility of the NAPL without having to create extremely low interfacial tensions (IFT).• Mobilization of NAPL is achieved by selection of a surfactant system that is capable of producing ultra-low IFTs which leads to the formation of stable microemulsion.• Mobilization is the preferred method for LNAPLs, while DNAPLs are more safely removed through solubilization.• In practice, both mobilization and solubilization will occur to some extent.

SEAF Technology Overview

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• Basic concepts of chemical-enhanced flushing have been in use since the 1920s in enhanced oil recovery operations.• Significant research on surfactant phase behavior and recovery of NAPLs was conducted by numerous universities through the 1980s-1990s including University of Florida, University of Oklahoma, and State University of New York.• Pilot and full-scale implementations began in the mid-1990s with primary focus on DNAPLs.• Initial work was conducted with higher concentrations of surfactants than are commonly employed today.• Oklahoma was one of the first states to widely accept and promote the technology.

History of Aquifer Flushing Remediation

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• Methods, Materials, and Techniques that;• are less harmful to the environment• conserve resourcesGreen

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Aquifer Flushing Schematic

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Green

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Case Studies

• Catastrophic tank failure.• Site geology predominantly clay to fine/medium sand with some gravel in base of aquifer.• Remedial objective was gasoline < 1/8 inch.• Smear zone 22-28 feet bgs, approximately 10,600 cubic yards.• System installed with a total of 70 remediation wells.• Well spacing was varied in order to maximize well density in center of plume.• At system start-up free product exceeded 1.5 feet.• 15 week operational phase eliminated all free product.• 7 month rebound monitoring verified no free product reoccurrence.

CITGO #1678, OCC Case 064-1247

Warr Acres, Oklahoma

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LNAPL Thickness Baseline 03/28/06 10

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LNAPL Thickness04/06/06

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LNAPL ThicknessClosure 07/05/06

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Remediation System with Vapor Control

CITGO #1678, OCC Case 064-1247

Warr Acres, Oklahoma

Remediation System

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Bio-Pile Vapor Controls

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Bio-Pile Vapor Controls

Case Studies

• Truck stop with historic line and tank leaks.• Remedial objective was free phase diesel <1/8 inch.• Site geology consisted of heterogeneous clay fill.• Depth to smear zone 4-15 feet bgs. • System consisted of 46 remediation wells.• Spacing was 15 feet due to slow injection rates.• Free product thicknesses greater than 1 foot prior to start-up.• Approximately 5,930 cubic yards remediated.• 15 week operational phase eliminated all free product.• 5 month rebound monitoring verified no free product reoccurrence.

Speedy’s 66, OCC Case 064-1796/2577, Catoosa, OK

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Historical LNAPL Extent19

Observed LNAPL Thickness05/25/06 20

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Case Studies

• Former retail marketing site with historic free product plume resulting from tank and line leaks.• Remedial objective was free product <1/8 inch.• Site geology predominantly sandstone with interbedded shales.• Depth to smear zone 7-15 feet bgs.• System was installed with 102 remediation wells.• Baseline gauging free product thicknesses exceeded 2 feet.• Total of 9,000 cubic yards remediated.• 26 week operational phase eliminated all free product.• Product associated with an off-site release was observed in two perimeter extraction wells. The system was re-activated to treat that area.• 8 month rebound monitoring verified no free product reoccurrence.

Hop & Sack Station, OCC Case 064-D2, Oklahoma City, OK

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Baseline August 2007

10/09/07

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Observed LNAPL Thickness

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11/05/07

12/12/07

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1/28/08

1/31/08

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Case Studies

• Active crane yard in Oklahoma City with well-defined free product plume greater than 1.5 feet thick.• Remedial objective was free product <1/8 inch.• Site geology consisted of river alluvium fine to medium sands with clay stringers.• Depth to smear zone 7-15 feet bgs.• System installed with a total of 78 remediation wells.• Total of 6,400 cubic yards remediated.• 16 week operational phase eliminated all free product.• 9 month rebound monitoring verified no free product reoccurrence.

Allied Steel Construction Company, OCC Case 064-2384, Oklahoma City, OK

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Baseline September 2008

10/29/08

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12/01/08

12/09/08

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Case Studies

• Former retail marketing facility with large free product plume on city and state right-of-way and adjacent properties.• Historic free product thicknesses greater than 7 feet.• Depth to smear zone 10-18 feet bgs.• Site geology consisted of moderately-cemented sandstones.• Typical remediation well array was not feasible due to the off-site free product plume, adjacent businesses, and streets.• Seven horizontal remediation wells were installed in addition to 21 vertical remediation wells.• Total of 13,200 cubic yards remediated. Costs were greater than typical due to horizontal drilling.• 26 week operational phase eliminated all free product.• 7 month rebound monitoring verified no free product reoccurrence.

Former Stockard’s CITGO, OCC Case 064-1679, Sapulpa, OK

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Remediation Well Layout

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Baseline Observed LNAPL ThicknessFebruary 2009

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Observed LNAPL Thickness 03/02/2009

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Documents

Green Aspects of Aquifer Flushing for Rapid Free Product