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