Two-Phase Extraction: A Comparative Evaluation of Two Case Histories for MTBE and TBA Removal 
Mehmet Pehlivan, Tait Environmental Management, Inc.

Ozone, Oxygen, and Hydrogen Peroxide Injection for Aggressive In-Situ Chemical Oxidation of MTBE and TBA
Charles B. Whisman, Groundwater & Environmental Services, Inc.
Peter Herlihy, Applied Process Technology, Inc.

Enhanced Natural Attenuation of MTBE & Benzene at a Low Permeability Site Using iSOC Technology 
Walter S. Mulica, Global Technologies, Inc., Fort Collins, CO
Nick Mathis, O&G Environmental, Inc., Englewood, CO
James F. Begley, MT Environmental Restoration, Plymouth, MA

Simulation of Effects on Ground Water From Small-Volume Releases of Gasohol in the Vadose Zone
Matthew A. Lahvis, Shell Global Solutions (US) Inc.

HiPOx Advanced Oxidation of TBA and MTBE in Contaminated Groundwater
Reid H. Bowman, Ph.D., Applied Process Technology, Inc.

Pulsed Microbubble Air/Ozone Perfusion for Gasoline Releases and Continuing Noncatastrophic Spill Control at Retail Outlets
William B. Kerfoot, K-V Associates, Inc.
Edward C. Ralston, ConocoPhillips
David J. Vossler, Gettler-Ryan, Inc.
Christopher J. Watt, Laco Associates

Investigation and Remediation of a Three-Dimensional MTBE Plume in Groundwater

James A. Berndt and John A. Mundell, Mundell & Associates, Inc., 429 East Vermont Street, Suite 200, Indianapolis, IN 46202, Tel: 317-630-9060, Fax: 317-630-9065

In the spring of 2002 a strong gasoline odor was reported in the drinking water at a small bulk petroleum facility in northern Indiana.  Subsequent testing of the water revealed the water contained high levels of benzene and MTBE.  The discovery of impacted drinking water at the site prompted investigation of drinking water wells on surrounding properties.  This investigation showed that one home (located 250 feet downgradient of the site) and an elementary school (located 1,500 feet downgradient of the site) both had MTBE-impacted water supplies.  The State of Indiana required the bulk facility owner to initiate a subsurface investigation to determine if it was the source of the MTBE-impacted groundwater, and if so, to delineate the plume extent.  Initial investigation of the site, using standard LUST investigation protocol, included numerous soil and groundwater samples collected across the site.  Preliminary surficial groundwater samples collected at the downgradient edge of the site indicated that the benzene and MTBE plume did not extend off site.  During the installation of permanent monitoring wells it was discovered that the MTBE plume had a strong vertical component and had moved off site near the base of the 40-foot thick sand aquifer.  The Subsequent delineation of the three-dimensional plume included 131 soil borings and the installation of 45 monitoring wells.  The delineated plume originated at the groundwater surface on the site and extended over 1,500 feet downgradient of the site at a depth of 25 to 40 feet below the groundwater surface.  It is apparent from this site that traditional LUST site investigation techniques, focused on the uppermost portion of the aquifer, would have failed to identify this large MTBE plume.  The evaluation of remedial alternatives for this plume will focus on in situ treatment.

Two-Phase Extraction: A Comparative Evaluation of Two Case Histories for MTBE and TBA Removal

Mehmet Pehlivan, RG, CHG, Senior Hydrogeologist, Tait Environmental Management, Inc., 701 N. Parkcenter Drive, Santa Ana, CA 92705, Tel: 714-560-8613, Fax: 714-560-8235

This paper presents the comparative evaluation of two remediation case studies in which a two-phase extraction method was used. In both cases, the two-phase extraction method was successful in extraction of the petroleum hydrocarbons from the soil and groundwater.

The first case is about a former gasoline service station with elevated concentrations of methyl-tert-butyl ether (MTBE) in groundwater. The MTBE concentrations in groundwater declined with the start of two-phase extraction and the tert-butyl alcohol (TBA) concentrations increased from non detect to over 10,000 micrograms per liter (ug/L) indicating in-situ biodegradation of MTBE to TBA.

The second case involves another fuel service station with MTBE concentrations over 800,000 ug/L. After the two-phase extraction started the MTBE was biodegraded to TBA causing an increase in the TBA concentration in the discharge water. A bioreactor was installed in order to meet the discharge requirements and to remove TBA from the discharge water. The bioreactor was designed such that it used the system vacuum source to aerate and re-circulate the water. 

Ozone, Oxygen, and Hydrogen Peroxide Injection for Aggressive In-Situ Chemical Oxidation of MTBE and TBA 

Charles B. Whisman, P.E., Director of Engineering, Groundwater & Environmental Services, Inc., 410 Eagleview Boulevard, Suite 110, Exton, PA, 19341, USA, Tel: 610-458-1077 (ext. 156), Fax: 610-458-2300, Email: cwhisman@gesonline.com
Peter Herlihy, Eastern Region Manager, Applied Process Technology, Inc., 3333 Vincent Road, Suite 222, Pleasant Hill, CA, 94523, USA, Tel: 925-977-1811, Fax: (925) 977-1818, Email: pherlihy@aptwater.com

There are many limitations with providing cost-effective remedial solutions for sites impacted with MTBE and TBA.  GES and APT have developed an aggressive in-situ chemical oxidation system to remediate MTBE and TBA at costs below conventional methods.  At our site in Delaware, the system was utilized at a site where a large dissolved-phase BTEX, MTBE, TAME, and TBA plume (approximately 800 feet in length) impacted numerous residential supply wells and properties.  Following pilot testing activities and a detailed life-cycle cost analysis of potential remediation technologies, the chemical oxidation process was selected since it was determined to be the most cost effective solution and indicated the shortest remedial life cycle.  The system involved injecting oxygen, ozone, compressed air, and hydrogen peroxide (via subsurface piping) to ten injection locations along two property boundaries.  Each of the injection locations contained two nested injection points: ozone, oxygen, and compressed air are injected into one injection point, and hydrogen peroxide is injected into the second injection point.  The total flow rate of the ozone, oxygen, and compressed air stream was high enough to create a radius-of-influence of greater than 15 feet at each injection location to remediate adsorbed-phase contaminants in surrounding saturated soils in addition to dissolved-phase contaminants.  The system control panel cycles the injection of ozone, oxygen, air, and hydrogen peroxide to the injection points to aggressively pulse the operation of the system.  As hydrogen peroxide is introduced with ozone, reactions take place to form hydroxyl radicals, which are very powerful oxidizers.  The presentation will evaluate the life cycle cost analysis which was utilized, detail the system design specifications and operational features, and evaluate the results of the technology at the Delaware site, where most of the dissolved-phase plume was remediated in the first three months of system operation.

Enhanced Natural Attenuation of MTBE & Benzene at a Low Permeability Site Using iSOC Technology

Walter S. Mulica, Global Technologies, Inc., 4808 Westridge Drive, Fort Collins, CO 80526, Tel: 970-377-1539, Fax: 970-377-3865
Nick Mathis, O&G Environmental, Inc., Englewood, CO 80112, Tel: 720-529-9777
James F. Begley, MT Environmental Restoration, 24 Bay View Avenue, Plymouth, MA  02360, Tel: 508-732-0121, Fax: 508-732-0122

The use of pure oxygen in groundwater to enhance natural attenuation of gasoline constituents (e.g. benzene, MTBE) has been growing as a remediation technology since the mid 1990’s.  Presently there are a variety of technologies available which will introduce dissolved oxygen into groundwater to supply oxygen for microbes.  Unfortunately, some oxygen delivery technologies such as air sparging and peroxide injections are not feasible or effective at low permeability sites.  Nearly 100 sites across the US are currently using the insitu Submerged Oxygen Curtain (iSOC™) technology.   Many of these sites are composed of sediments with low to very low permeabilities. Experience in the field has shown that in each well where an iSOC™ unit is installed, dissolved oxygen levels in excess of 40 to 60 parts per million (ppm) can easily be achieved.  The effective radius of influence of the iSOC™ in groundwater leaving the monitoring wells is typically 10-15 feet.  Dissolved oxygen concentrations of over 8 ppm in monitoring wells 60 feet down gradient of injection wells have been reported.  The iSOC technology was utilized at a low permeability Colorado site with MTBE and benzene concentrations as high as 195,000 μg/L and 5,000 μg/L, respectively in groundwater. A 6-month pilot test was conducted with an iSOC™ unit installed in one treatment well and was followed up with a full scale treatment system utilizing six iSOC™ treatment wells. Dissolved oxygen concentrations were monitored in treatment wells and monitoring wells.  In the highest concentration area of the plume, MTBE and benzene were reduced by more than 99%.

Simulation of Effects on Ground Water From Small-Volume Releases of Gasohol in the Vadose Zone

Matthew A. Lahvis, Shell Global Solutions (US), Inc., Westhollow Technology Center, 3333 Highway 6 South, Houston, TX 77082-3101, Tel: 281-544-7661 Fax: 281-544-8727
Email:  matthew.lahvis@shell.com

Transport modeling is used to evaluate potential ground-water contamination resulting from small-volume releases of gasohol (i.e., gasoline containing the fuel oxygenate ethanol - EtOH) in the vadose zone.  Mass fluxes (loading rates) and travel times of EtOH and benzene to ground water are predicted as a function of soil type, biodegradation rate, ground-water infiltration rate, and depth to ground water.  Model results indicate that EtOH migration is limited to less than 100 cm for a extremely conservative approximation of the biodegradation rate (k = 0.01 d^-1).  Transport of EtOH is primarily by aqueous-phase processes (diffusion and advection) because the compound is completely miscible.  Because vapor diffusion is not a relevant transport mechanism for EtOH, the capillary zone has little effect on mass transport.  Benzene migration to ground water is also significantly affected by biodegradation in the vadose zone.  In coarse-grained soils (e.g., sand), biodegradation limits transport to less than 100 cm assuming reasonable approximations of the biodegradation rate.  In finer-grained soils (e.g., sandy clay), benzene transport to ground water can be significant due to development of anaerobic conditions in the vadose zone.  Travel times to ground water can be more than an order of magnitude greater for EtOH than for benzene depending primarily on soil type, depth to ground water and biodegradation rate.  Collectively, these results indicate that small-volume releases of EtOH-blended gasoline in the vadose zone are not likely to cause significant ground water impacts unless located near the water table, or, in the case of benzene, biodegradation is limited.

HiPOx Advanced Oxidation of TBA and MTBE in Contaminated Groundwater 

Reid H. Bowman, Ph.D., Applied Process Technology, Inc., 3333 Vincent Road, Suite 222, Pleasant Hill, CA 94523, Tel: 805-649-5796, Fax: 805-649-5947, Email:  rbowman@aptwater.com

This paper presents results from several pilot studies and full-scale remediation sites in which an Advanced Oxidation Process (ozone/hydrogen peroxide) was used to remove TBA and MTBE from contaminated groundwater.  The concentration of TBA in the groundwater at the various sites ranged from 29 μg/L to 4,800 μg/L. The MTBE concentrations ranged from 42 to 110,000 μg/L.  The sites include abandoned gas stations, active gas stations and gasoline terminals located in California, Nevada and New Jersey.   At the full-scale remediation sites, the flow of contaminated water treated ranged from 5 to 60 gallons per minute (gpm).  While discharge requirements vary from site to site, we have demonstrated that the TBA and MTBE concentrations can be reduced to less than each site’s respective detection limits. Pilot work at each site allowed for the development of an empirical model to determine the concentrations of ozone and hydrogen peroxide demanded to meet the TBA and MTBE discharge requirements.  Comparisons between the pilot study results and the full-scale remediation site results demonstrate the scalability of this process.

Pulsed Microbubble Air/Ozone Perfusion for Gasoline Releases and Continuing Noncatastrophic Spill Control at Retail Outlets

William B. Kerfoot, K-V Associates, Inc., 766 Falmouth Rd., Unit B, Mashpee, MA  02649, Tel: 508-539-3002, Fax:  508-539-3566, Email:  wbkerfoot@kva-equipment.com
Edward C. Ralston, ConocoPhillips, 76 Broadway, Sacramento, CA  95812, Tel: 916-558-7633 , Fax: 916-558-7639, Email:  Ed.C.Ralston@ConocoPhillips.com
David J. Vossler, Gettler-Ryan, Inc., 1364 North McDowell Blvd., Suite B-2, Petaluma, CA  94934 Tel: 707-789-3252, Fax:  707-789-3218
Christopher J. Watt, Laco Associates, 21 W. 4^th Street, Eureka, CA  95501, Tel: 707-443-5054, Fax: 707-443-0553

Continued operation of periodic injection of air/ozone microbubbles into groundwater under retail dispensers of gasoline provides a level of protection against low volume releases from vapor or liquid during operation.  Four years of operation at spill sites has shown that the ozone targets higher health risk compounds, including aromatic additives (BTEX, naphthalenes, methylbenzenes) and oxygenates (MTBE, ETBE, TBA, TAME).  Periodic injection sufficient to bring the groundwater up to conditions of suitable oxidation potential (+200 mv) and dissolved oxygen content about 3 mg/L) maintains a suitable background condition for chemical oxidative decomposition and continuing heterotrophic bacterial decomposition of common carboxylic acids or alcohol fractions resulting from oxidation.  A summary of experiences at numerous sites is presented.  Whereas initial remediation of a prior spill may involve short-term use of higher concentrations of oxidant, long-term pulsing requires a balance between maintaining optimal conditions for petroleum compound removal and avoiding impact to nontarget site materials.  To evaluate the level of risk of damage, a ranking of structural materials and sensitivity to ozone was compiled from existing sources.  The expected concentration of ozone with distance in both gaseous and aqueous forms under microbubble production was compared to materials sensitivity (when available) to prepare a set of standard safety operating procedures.  Conditions such as groundwater level beneath grade were found to be an important factor.

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