Monday, November 5, 2007 : 4:10 p.m.

Technology Selection for Gasoline-Impacted Ground Water

David A. Klemme, PE1, Keith A. Romstad, PG1 and Ellen E. Moyer, Ph.D., PE2, (1)Environmental Resolutions Inc., (2)Greenvironment LLC

A key to cost-effective remediation of dissolved gasoline constituents is selection of the appropriate technology for a given site.  Through the authors’ collective experience remediating scores of gasoline release sites, we offer some general guidelines on selecting the most appropriate and least-cost solution.  This paper focuses on remediation technologies that involve the extraction of soil vapor or groundwater.  Typical active gasoline remedial alternatives include air sparging/soil vapor extraction (AS/SVE) followed by offgas treatment, and groundwater extraction followed by ex-situ treatment.  Ex-situ groundwater treatment options include air stripping, granular activated carbon (GAC) adsorption and bioreactor treatment.  How to decide?  The decision is site-specific, depending on such factors as contaminant concentrations, groundwater and soil vapor extraction rates, soil heterogeneity, depth to groundwater, groundwater flow rate, proximity to receptors, required cleanup concentrations, site access, and utilities.  We have found that, in general, the following guidelines can be considered, and as appropriate, modified given site-specific conditions.  AS/SVE is typically not effective for dissolved fuel oxygenate concentrations exceeding 500 µg/L because fuel oxygenates are not easily sparged from the groundwater into the vadose zone where they can be extracted.  On the other hand, AS/SVE has proven to be effective in removing dissolved petroleum hydrocarbons.  For fuel oxygenates concentrations exceeding 500 µg/L, groundwater extraction and treatment will generally be a more cost-effective remediation approach.  Following extraction, the ex situ technology is selected based upon mass loading (i.e., water extraction rate times the total concentration of gasoline constituents).  If MTBE is the primary contaminant, we have found that at mass loadings less than about 10,000 gpm-µg/L, GAC adsorption is typically more cost-effective; whereas at mass loadings greater than that, bioreactor treatment is more cost-effective.  If TBA is the primary contaminant, bioreactor treatment is more cost-effective than GAC at virtually any mass loading.

David A. Klemme, PE, Environmental Resolutions Inc. David Klemme, P.E., is Environmental Resolutions, Inc.’s Principal Engineer. He has a B.S. in Mechanical Engineering and a Professional Certificate in Environmental Site Assessment and Remediation. He has approximately 12 years of experience assessing and remediating soil and groundwater contamination and has managed the remediation of over 75 sites. His focus is the development of designs and specifications for soil and groundwater remedial systems; pilot testing; permitting; system construction, installation, and startup; operations and maintenance; regulatory compliance; system performance evaluations; and site closure.

Keith A. Romstad, PG, Environmental Resolutions Inc. Keith Romstad, P.G., is Vice President and Chief Operating Officer for Environmental Resolutions, Inc. He has a B.S. in Geology and approximately 20 years of experience conducting environmental investigations. He has specialized in claims and litigation support, dispute resolution and allocations, and fate and transport of contaminants, including evaluating pumping test data and performing groundwater modeling. He has experience in carrying out all aspects of environmental geologic investigations, from developing programs, handling logistics, and acting as a liaison between the client and governmental agencies, to developing and observing clean-up activities for soil and groundwater containing petroleum hydrocarbons.

Ellen E. Moyer, Ph.D., PE, Greenvironment LLC Ellen Moyer, Ph.D., P.E is a recognized expert in the assessment and remediation of VOC contamination. She has an M.S. in Environmental Engineering, a Ph.D. in Civil Engineering, and over 20 years of professional experience. Dr. Moyer has managed all phases of assessment and remediation work, and her numerous projects have employed a wide range of in situ and ex situ remediation technologies at diverse sites with organic and inorganic contaminants. She was the lead editor of an MTBE Remediation Handbook, now in its second printing. Her Ph.D. research investigated soil vapor extraction, air sparging, and bioventing of gasoline VOCs.


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Petroleum Hydrocarbons and Organic Chemicals in Ground Water: Prevention, Detection, and Remediation® Conference