Gasoline Oxygenate Use, Groundwater Issues and Related Research
Bruce Bauman, American Petroleum Institute,Washington, DC

Trends in the Occurrence of MTBE in Drinking Water in the Northeast United States
Michael Moran, U.S. Geological Survey, Rapid City , SD

3D Expedited Characterization Methodology for MTBE Contamination Impacting Deep Public Drinking Water Supply Wells
Joselph E. Haas II, New York State Department of Environmental Conservation, Stony Brook , NY

Behavior of Ethanol and Aromatic Hydrocarbons from Two Gasoline Releases and One Natural Gradient Experiment, CFB Borden
Marian Mocanu, University of Waterloo , Waterloo , ON  

Field Performance Comparison of Three Oxygen Distribution Technologies
Cristin L. Bruce, Shell Global Solutions (US) Inc., Houston , TX

Results and Lessons Learned from Field Applications of Oxygen Distribution Technologies
Gerald Spinnler, Shell Global Solutions (US) Inc., Houston , TX

Gasoline Oxygenate Use, Ground Water Issues and Related Research

Bruce Bauman , API, Washington DC

Conventional gasoline (CG) and Reformulated Gasoline (RFG) are the two basic types of gasoline used in the United States to meet federal and state regulatory requirements.  There has been a virtual national phase-out of MTBE from all US gasoline over the last several years, and EPA no longer requires a minimum oxygen content in RFG.  However, federal and some state regulations require the use of ethanol in gasoline, and currently about 50% of the gasoline blended in the US contains ethanol, usually at 10% volume.  Domestic production and use of ethanol is predicted to double within the next several years from its current (2007 estimate) 6 billion gallons, and EPA is currently developing regulations to implement the Bush administration “20 in 10” initiative that would replace 20% of US gasoline (~ 30 billion gallons) with alternative fuels within 10 years.   Language in current 2007 federal Energy Bill legislation would require 35 billion gallons by 2022, so it is highly likely that ethanol gasolines of varying blends will become even more prevalent.  Except for specialty fuels like E85 (~81% ethanol), EPA regulations prohibit >10% ethanol in gasoline, but there are also initiatives to allow ethanol blends of 11-20% for use in all gasoline motor vehicles.  E85 blends are already widely available in the Midwest and heavily promoted by US auto makers.  This broad-scale transition means that all parts of the US are likely to have ethanol present in gasoline, and all spill response personnel will need to develop a thorough understanding of how releases of these fuels might behave differently than gasolines without ethanol.  It will become necessary to catalog all known release scenarios ( e.g., small chronic releases, sudden large releases) and receptors (e.g., ground water, surface water, utilities) for these different types of gasolines.  Existing conceptual models for spill response and corrective action require should be reviewed to determine if any modifications might be helpful to fully account for all important direct and indirect effects. API research has been developing some of this information over the last several years, and will continue to focus on key fate and transport issues as well as corrective action technologies. 

Trends in the Occurrence of MTBE in Drinking Water in the Northeast United States

Michael Moran, Ph.D., U.S. Geological Survey, 1608 Mountain View Road, Rapid City, SD 57702, Tel: 605-394-3244, Email: mjmoran@usgs.gov

Public water systems in Connecticut, Maine, Maryland, New Hampshire, New Jersey, and Rhode Island sampled treated drinking water from 1990-2006 and analyzed the samples for methyl tert-butyl ether (MTBE).  The U.S. Geological Survey examined trends in the occurrence of MTBE in drinking water from these public water systems in the Northeast United States . 

MTBE was detected in 15% of drinking water samples collected in 1990-1999 and in 21% of drinking water samples collected from the same systems in 2000-2006.  The difference in occurrence of MTBE between these two time periods is statistically significant; however, a significant increase in the occurrence of MTBE was observed in only three individual States: Maryland , New Jersey , and Rhode Island .  Trends in MTBE occurrence by year in each State were less informative because of the inconsistent number of systems sampled in each year.  Nonetheless, significant positive trends in the occurrence of MTBE by year were identified in Connecticut and Maryland . 

Most concentrations of MTBE in drinking water from public water systems were low and median concentrations by State were less than 2 micrograms per liter.  Using paired data for drinking water from ground water sources, significant trends in MTBE concentrations were observed in Maryland and Rhode Island .  Concentrations of MTBE increased in both States from 1990-1999 to 2000-2006.

Water that is contaminated by MTBE is increasingly being captured by public water supplies in the Northeast and transmitted to consumers, although most concentrations are considerably less than those that might cause taste and odor concerns.  As a result of the Energy Policy Act of 2005 the use of MTBE in gasoline has significantly declined.  Future trends in the occurrence of MTBE in public water systems supplied from ground water in the Northeast are uncertain due to many potential controlling factors such as the continued decline in use of MTBE, recharge, pumpage, and geology.

3D Expedited Characterization Methodology for MTBE Contamination Impacting Deep Public Drinking Water Supply Wells 

Joseph E. Haas II, M.Sc., P.Eg.P.Hg., New York State Department of Environmental Conservation, SUNY @ Stony Brook, 50 Circle Road, Stony Brook, NY 11790-3409, Tel: 631-444-0332, Email: jehaas@gw.dec.state.ny.us
Donald A. Trego, Environmental Assessment & Remediations, 225 Atlantic Avenue , Patchogue, NY11772, Tel: 631-447-6400, Email: Trego@ENVIRO-ASMNT.COM
Kevin G. Hale, New York State Department of Environmental Conservation, 625 Broadway , Albany , NY 12233 , Tel: 518-402-9549, Email: kghale@gw.dec.state.ny.us

The production, distribution and utilization of MTBE as a component of motor fuels has resulted in widespread impacts to ground water quality and has resulted in significant impacts upon public drinking water supply wells. MTBE contamination has forced the temporary closure of wells supplying the localities of Santa Monica, CA, South Lake Tahoe, CA, Pascoag, RI, Liberty, NY, Cambria Heights, NY, Riverhead, NY, and West Hempstead, NY. Despite MTBE bans enacted by many states MTBE, detections in public drinking water supply wells continue. 

Past MTBE impacts to drinking water supply wells in New York prompted the development of three dimensional (3D) expedited site characterization (ESC) techniques to rapidly back-track the path of contamination. However, the effective depth for application of the ESC techniques has been limited to approximately 40 meters by the depth capabilities of direct push sampling devices and hollow stem auger drilling equipment. Recent MTBE impacts to deeper public drinking water supply wells has catalyzed efforts to identify sampling and drilling techniques with greater depth capabilities that could be integrated in to the ESC methodology.  

The feasibility of integrating rotosonic drilling into the ESC was evaluated via the pilot installation of two multi-level nested well bundles (MLNWBs) by rotosonic methods. The MLNWBs were installed adjacent to the intake screens of two deep public drinking water supply wells (approximately of 100 meters) that were exhibiting MTBE impacts. The installations of the MLNWBs were without incident, demonstrating the technical viability of the rotosonic techniques as a component of a deep ESC methodology. 

MTBE contamination detected in the West Hempstead Water District Birch Street Well Field at a concentration of 154 micrograms per liter ( μg/L) at depths of approximately 60 meters was defined utilizing a modified ESC for deep MTBE contamination. In this case the dynamic installation of MLNWBs was via cased hole drilling methods, which coupled with immediate field analysis of environmental samples successfully defined the MTBE contamination in 3D to depths of 60 meters. The experience gained at the West Hempstead site in combination with data obtained from the rotosonic pilot study indicates that 3D ESC definition of groundwater contamination to depths of 100 meters can be accomplished in “real-time” when required.   

Behavior of Ethanol and Aromatic Hydrocarbons from Two Gasoline Releases and One Natural Gradient Experiment, CFB Borden

Marian Mocanu, Dept. of Earth Sciences, University of Waterloo, Waterloo, ON, Canada, Email: mtmocanu@scimail.uwaterloo.ca Dinah Augustine, Dept. of Earth Sciences, University of Waterloo, Waterloo, ON, Canada, Email: dinah.augustine@gmail.com
José Luiz Gomes Zoby, Instituto de Geociências, University of São Paulo, São Paulo, Brazil, Email: jlgzoby@hotmail.com
Erika Williams, Dept. of Earth Sciences, University of Waterloo, Waterloo, ON, Canada, Email:  ewilliams@alumni.uwaterloo.ca
John Molson, Dept. of Earth Sciences, University of Waterloo, Waterloo, ON, Canada, Email:  molson@uwaterloo.ca
Jim Barker, Dept. of Earth Sciences, University of Waterloo, Waterloo, ON, Canada, Tel: 519-888-4567, ext. 32103, Fax: 519-746-7484, Email:  jfbarker@sciborg.uwaterloo.ca

The development and fate of groundwater plumes derived from two emplaced oxygenate-gasoline residuals in the Borden Research Aquifer were recently monitored. One fuel contains 90% gasoline and 10% ethanol (E10); the second contains denatured ethanol with 95% ethanol and 5% gasoline (E95). Ethanol from both E10 and E95 sources dissolved quickly into the flowing groundwater and, in both cases, > 60% of the ethanol was biotransformed during the 15 m (150 days) downgradient transport. Laboratory studies suggest that the maximum ethanol levels in groundwater at the E95 source (about 7000 mg/L) were not likely inhibitory to aquifer BTEX-degrading microorganisms, but that ethanol and its metabolites such as acetate would be preferred substrates compared to BTEX in the competition for electron acceptors. Essentially all aromatic hydrocarbons were leached from the E95 source while only benzene has been completely leached from the E10 source after 600 days. Ethanol cosolvency may have caused unexpectedly high fluxes of benzene and toluene from the E95 source. The presence of significant dissolved ethanol seems to have essentially stopped benzene and toluene degradation in the E95 plume for at least the 15m section that was monitored. Ethanol may have also reduced the biotransformation rate of benzene and toluene in the E10 plume , but had little effect on the persistence of less-mobile o-xylene and 1,2,3-trimethylbenzene, perhaps because the ethanol plume moves faster than the xylene and trimethylbenzenes. This is consistent with a previous natural gradient experiment at Borden in which two slugs of groundwater, one amended with about 15 mg/L BTEX and the other with about 6000 mg/L methanol added as well, were followed for 376 days. The methanol degraded with an apparent first order rate constant of  0.019 day-1 and the methanol caused significantly slower rates of benzene biodegradation (apparent first order rate constants of  0.001 day-1 and 0.004 day-1 with and without methanol respectively).  

Numerical modeling using BIONAPL demonstrates that ethanol in gasoline does have the potential to create longer-than-anticipated benzene plumes in groundwater. At later time, the residual hydrocarbon source will likely behave as a non-oxygenate source and so subsequent source and plume management by MNA should continue to be the preferred remedial response.

Results and Lessons Learned from Field Applications of Oxygen Distribution Technologies

Cristin L. Bruce, Shell Global Solutions (US) Inc., 3333 Hwy 6 South, EC-222, Houston , TX 77082 , Tel: 281-544-7552, Fax: 281-544-8727,Email: cristin.bruce@shell.com
Paul M. Maner, Shell Global Solutions (US) Inc., 3333 Highway 6 South, Houston , TX 77082 Tel: 281-544-7351, Fax: 281-544-8727, Email: paul.maner@shell.com
Gerard E. Spinnler, Shell Global Solutions (US) Inc., 3333 Hwy 6 South, EC-246, Houston , TX 77082 , Tel: 281-544-7351, Fax: 281-544-8727, Email:  gerard.spinnler@shell.com

,Remediating oxygenate plumes by stimulating indigenous aerobic microorganisms is a proven technology.  Oxygen distribution is essential for the technology to be effective. Unfortunately, oxygen distribution is difficult in many geologic environments. 

Oxygen Pulsed Injection Systems (OPIS) use discrete volume injections of nearly pure oxygen to increase the DO of the groundwater.  Distribution around the injection well is achieved by relatively high (>10 scfm) flow rates for discrete and short (~60 seconds) time intervals.  Systems of this design have been installed at several retail and former retail sites in a variety of geologic settings.  Experiences using this technology and site data will be presented.

Field Performance Comparison of Three Oxygen Distribution Technologies 

Cristin L. Bruce, Shell Global Solutions (US), 3333 Hwy 6 South, EC-222, Houston , TX 77082 Tel: 281-544-7552 Fax: 281-544-8727, Email: cristin.bruce@shell.com
Gerard E. Spinnler, Shell Global Solutions (US), 3333 Hwy 6 South, EC-246, Houston , TX 77082 Tel: 281-544-7351 Fax: 281-544-8727, Email: gerard.spinnler@shell.com
Paul R. Dahlen, Arizona State University , POB 875306, Tempe , AZ 85287-5306 Tel: 480-965-0055 Fax: 480-965-7205, Email: paul.dahlen@asu.edu 
Jennifer Triplett, Arizona State University , POB 875306, Tempe , AZ 85287-5306 Tel: 480-965-0055 Fax: 480-965-7205, Email: jennifer.triplett@asu.edu
Paul C Johnson, Arizona State University , POB 875306, Tempe , AZ 85287-5306 Tel: 480-965-9115 Fax: 480-965-7205, Email: paul.c.johnson@asu.edu

There is keen interest in oxygen injection systems owing to the increased evidence of in situ aerobic biodegradation of potentially recalcitrant gasoline constituents.  Significant remediation cost reductions are possible by stimulating indigenous microorganisms to degrade contaminants of concern by adding oxygen.  Various commercial oxygen injection approaches are being marketed with little credible evidence supporting their claims.

A field demonstration of 3 oxygen distribution technologies was performed in side-by-side test cells at the Port Hueneme NETTS field site.  Each test cell measured 50-ft by 50-ft and was instrumented with 60 to 80 monitoring wells.  These wells were sampled at 4 to 6 week intervals in order to evaluate the extent of oxygen distribution to a medium-sand aquifer.  After 1 month of operation, the pulsed oxygen injection test cell showed a 10 to 20-ft oxygen-enriched (dissolved oxygen > 4 ppm) ROI, the low-flow, microbubble test cell showed a 5 to 15-ft oxygen-enriched ROI, and the diffusion-based test cell showed no influence outside the injection well (less than 1.5-ft ROI).  After 1 month, each test cell showed essentially stable dissolved oxygen signatures. 

This presentation will also illustrate the stability of the oxygen plumes in the diffusion and low-flow, microbubble test cells by mapping dissolved oxygen concentrations at 6, 12, and 18 weeks after cessation of oxygen injection.

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