Use of Long-Term Monitoring Data to Evaluate Benzene, MTBE, and TBA Plume Behavior in Groundwater at Retail Gasoline Sites

Kamath, Roopa; Connor, John A.; McHugh, Thomas E.; Lé, Micheline; Ryan, A. J.

doi:10.1061/(asce)ee.1943-7870.0000488

Cited by 22 publications

(46 citation statements)

References 2 publications

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“…The other 170 sites where MNA was identified as a remediation technology were also identified as having an active remediation technology. However, an earlier study based on a more detailed evaluation of a smaller number of sites found no significant difference in attenuation rates between MNA sites and sites with active groundwater remedies (Kamath et al 2011 vapor extraction appear to be effective at increasing both benzene and MTBE source attenuation rates, compared to sites where a mixture of other technologies was applied. An examination of the mode of action for specific technologies on the source attenuation rates for benzene vs. MTBE suggests that at least some of the differences in attenuation rates between sites with and without individual technologies are attributable to the effect of the technology.…”

Section: Effect Of Remediation Technology On Source Attenuation Ratesmentioning

confidence: 82%

Progress in Remediation of Groundwater at Petroleum Sites in California

McHugh¹,

Kulkarni

Newell

et al. 2013

Groundwater

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Quantifying the overall progress in remediation of contaminated groundwater has been a significant challenge. We utilized the GeoTracker database to evaluate the progress in groundwater remediation from 2001 to 2011 at over 12,000 sites in California with contaminated groundwater. This paper presents an analysis of analytical results from over 2.1 million groundwater samples representing at least $100 million in laboratory analytical costs. Overall, the evaluation of monitoring data shows a large decrease in groundwater concentrations of gasoline constituents. For benzene, half of the sites showed a decrease in concentration of 85% or more. For methyl tert-butyl ether (MTBE), this decrease was 96% and for TBE, 87%. At remediation sites in California, the median source attenuation rate was 0.18/year for benzene and 0.36/year for MTBE, corresponding to half-lives of 3.9 and 1.9 years, respectively. Attenuation rates were positive (i.e., decreasing concentration) for benzene at 76% of sites and for MTBE at 85% of sites. An evaluation of sites with active remediation technologies suggests differences in technology effectiveness. The median attenuation rates for benzene and MTBE are higher at sites with soil vapor extraction or air sparging compared with sites without these technologies. In contrast, there was little difference in attenuation rates at sites with or without soil excavation, dual phase extraction, or in situ enhanced biodegradation. The evaluation of remediation technologies, however, did not evaluate whether specific systems were well designed or implemented and did not control for potential differences in other site factors, such as soil type.

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Section: Effect Of Remediation Technology On Source Attenuation Ratesmentioning

confidence: 82%

Progress in Remediation of Groundwater at Petroleum Sites in California

McHugh¹,

Kulkarni

Newell

et al. 2013

Groundwater

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“…; Kamath et al. ), while some have used models to estimate potential travel distances (Mace et al. ).…”

Section: Resultsmentioning

confidence: 99%

“…, (c) Newell and Connor , and (d) Kamath et al. . The number associated with each bar is the number of sites with benzene plume‐length results.…”

Section: Resultsmentioning

confidence: 99%

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An Empirical Evaluation of the Influence of Ethanol on Natural Attenuation of Gasoline Constituents

O’Reilly¹,

Devine²,

Sihota³

et al. 2016

Groundwater Monitoring Rem

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Since the 1990s, questions have arisen as to whether the release of ethanol‐blended fuel will inhibit natural attenuation of other gasoline constituents in groundwater. This study evaluated the hypothesis that ethanol affects hydrocarbon attenuation and whether the use of ethanol‐blended fuel alters the applicability of monitored natural attenuation (MNA) as an approach for managing risks at fuel‐release sites. Groundwater data from California's GeoTracker database were used to compare attenuation of benzene, toluene, methyl tert‐butyl ether (MTBE), and tert‐butyl alcohol (TBA) at sites with and without detections of ethanol. Excel‐based tools were developed to conduct attenuation evaluations on thousands of wells simultaneously. Ethanol was detected at least once in 4.5% of the wells and 0.6% of the samples of which it was analyzed. The distribution of Mann‐Kendall concentration trend analysis results and first‐order attenuation rates were essentially the same at sites with or without ethanol detections. Median plume lengths were shorter at sites where ethanol had not been detected compared to sites where ethanol was detected (36 vs. 43 m for benzene; 36 vs. 42 m for toluene; 43 vs. 52 m for MTBE; and 44 vs. 59 m for TBA). However, the distribution of plume lengths was similar irrespective of ethanol concentrations, suggesting other factors may influence plume elongation. Finally, while anaerobic ethanol degradation can result in methane generation, the distributions of methane concentrations were the same at sites with and without ethanol detections. These results suggest that the use of ethanol‐blended fuel should not limit the application of MNA at most biodegrading fuel‐release sites.

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“…In addition, Jackson and Cross have provided no data to support their statement that response time from detection to full‐plume capture is a critical factor preventing long MTBE/TBA plumes at this site. To the contrary, Kamath et al () and McHugh et al () have shown no significant difference in source area attenuation rates between monitored natural attenuation sites and sites implementing active remediation technologies. Installation of groundwater remediation systems, in advance of proper characterization, can result in inefficient capture and remediation of the affected groundwater.…”

mentioning

confidence: 94%