air and ozone sparging of tce using a directionally drilled horizontal well site 86, camp lejeune...
Post on 17-Dec-2015
216 Views
Preview:
TRANSCRIPT
Air and Ozone Sparging of TCE Using a Directionally Drilled Horizontal Well
Site 86, Camp Lejeune
Mark Strong, P.E. CH2M HILLChristopher Bozzini, P.E. CH2M HILL
Daniel Hood, NAVFAC Mid-Atlantic
Bob Lowder, MCB Camp Lejeune EMD
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 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
• 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 (40-45’ bgs)
TCE in Plume in 2002 (50-55’ bgs)
Site 86 Cross Section
Directional Drill Rig On-Site
Air Sparge ‘Screen”
4” SDR 11 HDPE Pipe
0.020 Inch Wide Slots
0.5% Open Area
Directional Sparge Well Layout
Total Length of Drill = 950’
Total Slotted Length - 350’
Compressor and Ozone Generator Temporary Buildings (Connex Boxes)
Ozone Generator Chiller
Air Compressor, Receiver, Gas Cooler
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 40-45 ft bgs
Baseline TCE Concentrations, Feb ‘05 50-55 ft bgs
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 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 ConcentrationsZone “B” Monitoring Wells (40 - 45’ Screen Depth)
Average TCE ConcentrationsZone “C” Monitoring Wells (50 - 55’ Screen Depth)
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
Example Dissolved Oxygen and ORP Trend
Summary of Analytical Data
Well ID Date Sampled TCE01/06/2005 220
01/26/2006 .13 J
10/19/2004 0.13
01/26/2006 .17 J
10/19/2004 600
01/26/2006 < 0.50
10/19/2004 320
01/26/2006 .24 J
10/20/2004 0.31
01/26/2006 .3 J
10/20/2004 870
01/26/2006 0.88
10/19/2004 29
01/26/2006 35
86-GW36IWA
86-GW36IWB
86-GW36IWC
86-GW33IW
86-GW35IWA
86-GW35IWB
86-GW35IWC
Well ID Date Sampled TCE10/19/2004 0.11
01/26/2006 .48 J
10/18/2004 250
01/26/2006 1.9
10/18/2004 28
01/26/2006 14
10/19/2004 4.3
01/26/2006 .14 J
10/19/2004 480
01/26/2006 0.94
10/19/2004 1200
01/26/2006 0.74
86-GW38IWB
86-GW38IWC
86-GW37IWA
86-GW37IWB
86-GW37IWC
86-GW38IWA
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
$750K Total Budget Horizontal Well, Compressed Air System,
Container, Electrical ~ $250K Ozone System and Container ~ $300K Monitoring ~ $100K O&M ~ $100K
top related