Published on February 20, 2008
Air and Ozone Sparging of TCE Using a Directionally Drilled Horizontal WellSite 86, Camp Lejeune: Air and Ozone Sparging of TCE Using a Directionally Drilled Horizontal Well Site 86, Camp Lejeune Mark Strong, P.E. CH2M HILL Christopher Bozzini, P.E. CH2M HILL Daniel Hood, NAVFAC Mid-Atlantic Bob Lowder, MCB Camp Lejeune EMD Camp Lejeune Background: Camp Lejeune Background Second largest U.S. Marine Corps Base in the Country Camp Lejeune was established near the city of Jacksonville, N.C, in 1942. Base covers 236 square miles CERCLA site since 1989 22 Operable Units (OUs), 97 Sites. Site Location and History: Site Location and History Site 86 is associated with three former waste oil ASTs, used during the 70s and 80s Over the course of several investigations since 1992, the solvent plume migrated away from the source area and now extends several hundred feet off-site Bld. 25 Pilot Test Objectives: Pilot Test Objectives Prevent further migration of the TCE plume off-site Evaluate air (and ozone) distribution using a horizontal well Determine if ozone and/or air sparging can reduce TCE impacts to below regulatory standards within one year TCE in Plume in 2002 (30-35’ bgs): TCE in Plume in 2002 (30-35’ bgs) TCE in Plume in 2002 (40-45’ bgs): TCE in Plume in 2002 (40-45’ bgs) TCE in Plume in 2002 (50-55’ bgs): TCE in Plume in 2002 (50-55’ bgs) Site 86 Cross Section: Site 86 Cross Section Directional Drill Rig On-Site: Directional Drill Rig On-Site Air Sparge ‘Screen”: Air Sparge ‘Screen” 4” SDR 11 HDPE Pipe 0.020 Inch Wide Slots 0.5% Open Area Directional Sparge Well Layout: Directional Sparge Well Layout Total Length of Drill = 950’ Total Slotted Length - 350’ Compressor and Ozone Generator Temporary Buildings (Connex Boxes): Compressor and Ozone Generator Temporary Buildings (Connex Boxes) Ozone Generator Chiller: Ozone Generator Chiller Air Compressor, Receiver, Gas Cooler: Air Compressor, Receiver, Gas Cooler Ozonia Generator (CFV-03, 60 ppd, air feed) : Ozonia Generator (CFV-03, 60 ppd, air feed) Photo courtesy Ozonia North America Baseline TCE Concentrations, Feb ‘05 30-35 ft bgs: Baseline TCE Concentrations, Feb ‘05 30-35 ft bgs Baseline TCE Concentrations, Feb ‘05 40-45 ft bgs: Baseline TCE Concentrations, Feb ‘05 40-45 ft bgs Baseline TCE Concentrations, Feb ‘05 50-55 ft bgs: Baseline TCE Concentrations, Feb ‘05 50-55 ft bgs Schedule: Schedule Three Months of Air Sparging (120-140 cfm) One Month of “Rebound” Monitoring Six Months of Ozone Enhanced Air Sparging (~ 7000 ppmv) Three Months of “Rebound” Monitoring (Recently Completed) Ozone Injection Performance: Ozone Injection Performance Ozone production began in late July, 2005 Intermittent operation from July to December Mechanical issues: desiccant dryer and chiller Total aggregate run time ~ 2-1/2 months (50% up time) Total mass of ozone delivered ~ 3900 pounds Average TCE ConcentrationsZone “A” Monitoring Wells (30-35’ Screen Depth): Average TCE Concentrations Zone “A” Monitoring Wells (30-35’ Screen Depth) Average TCE ConcentrationsZone “B” Monitoring Wells (40 - 45’ Screen Depth): Average TCE Concentrations Zone “B” Monitoring Wells (40 - 45’ Screen Depth) Average TCE ConcentrationsZone “C” Monitoring Wells (50 - 55’ Screen Depth): Average TCE Concentrations Zone “C” Monitoring Wells (50 - 55’ Screen Depth) Discussion: Discussion SVE was not conducted because of low permeability overburden; trace levels of TCE measured in shallow vapor during operation (ppbv) Air was diverted horizontally by overburden; air bubbling was observed 300 feet from the well Lateral propagation of air “fingering” was estimated to be 50 feet on either side of the well, as indicated by dissolved oxygen concentrations Negligible increases in dissolved chloride from baseline levels Conceptual Model: Conceptual Model Example Dissolved Oxygen and ORP Trend: Example Dissolved Oxygen and ORP Trend Summary of Analytical Data: Summary of Analytical Data Conclusions: Conclusions 90% average reduction of TCE within three months in wells with baseline TCE > 50 μg/L 99% average reduction within one year in wells with baseline TCE > 50 μg/L No significant rebound after three months (greater than 25 µg/L) Distance of influence ~ 50 ft on both sides of the well (as indicated by DO measurements) Possible contribution of ozone to TCE mass reduction inconclusive - low TCE concentrations and limited period of operation Summary of Costs: Summary of Costs $750K Total Budget Horizontal Well, Compressed Air System, Container, Electrical ~ $250K Ozone System and Container ~ $300K Monitoring ~ $100K O&M ~ $100K
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