Leaking Underground Storage Tanks Research Articles

Microbial community response to hydrocarbon exposure in iron oxide mats: an environmental study.

Hydrocarbon pollution is a widespread issue in both groundwater and surface-water systems; however, research on remediation at the interface of these two systems is limited. This interface is the oxic-anoxic boundary, where hydrocarbon pollutant from contaminated groundwaters flows into surface waters and iron mats are formed by microaerophilic iron-oxidizing bacteria. Iron mats are highly chemically adsorptive and host a diverse community of microbes. To elucidate the effect of hydrocarbon exposure on iron mat geochemistry and microbial community structure and function, we sampled iron mats both upstream and downstream from a leaking underground storage tank. Hydrocarbon-exposed iron mats had significantly higher concentrations of oxidized iron and significantly lower dissolved organic carbon and total dissolved phosphate than unexposed iron mats. A strong negative correlation between dissolved phosphate and benzene was observed in the hydrocarbon-exposed iron mats and water samples. There were positive correlations between iron and other hydrocarbons with benzene in the hydrocarbon-exposed iron mats, which was unique from water samples. The hydrocarbon-exposed iron mats represented two types, flocculent and seep, which had significantly different concentrations of iron, hydrocarbons, and phosphate, indicating that iron mat is also an important context in studies of freshwater mats. Using constrained ordination, we found the best predictors for community structure to be dissolved oxygen, pH, and benzene. Alpha diversity and evenness were significantly lower in hydrocarbon-exposed iron mats than unexposed mats. Using 16S rDNA amplicon sequences, we found evidence of three putative nitrate-reducing iron-oxidizing taxa in microaerophile-dominated iron mats (Azospira, Paracoccus, and Thermomonas). 16S rDNA amplicons also indicated the presence of taxa that are associated with hydrocarbon degradation. Benzene remediation-associated genes were found using metagenomic analysis both in exposed and unexposed iron mats. Furthermore, the results indicated that season (summer vs. spring) exacerbates the negative effect of hydrocarbon exposure on community diversity and evenness and led to the increased abundance of numerous OTUs. This study represents the first of its kind to attempt to understand how contaminant exposure, specifically hydrocarbons, influences the geochemistry and microbial community of freshwater iron mats and further develops our understanding of hydrocarbon remediation at the land-water interface.

Exploring the association of Brownfield remediation status with socioeconomic conditions in Wayne County, MI

Urban neighborhoods with locations of environmental contamination, known as brownfields, impact entire neighborhoods, but corrective environmental remedial action on brownfields is often tracked on an individual property basis, neglecting the larger neighborhood-level impact. This study addresses this impact by examining spatial differences between brownfields with unmitigated environmental concerns (open site) and sites that are considered fully mitigated or closed in urban neighborhoods (closed site) on the US census tract scale in Wayne County, MI. Michigan’s Department of Environment, Great Lakes, and Energy’s leaking underground storage tank (LUST) database provided brownfield information for Wayne County. Local indicators of spatial association (LISA) produced maps of spatial clustering and outliers. A McNemar’s test demonstrated significant discordances in LISA categories between LUST open and closed sites (p < 0.001). Geographically weighted regressions (GWR) evaluated the association between open and closed site spatial density (open-closed) with socioeconomic variables (population density, proportion of White or Black residents, proportion of college educated populations, the percentage of owner-occupied units, vacant units, rented units, and median household value). Final multivariate GWR showed that population density, being Black, college education, vacant units, and renter occupied units were significantly associated (p < 0.05) with open-closed, and that those associations varied across Wayne County. Increases in Black population was associated with increased open-closed. Increases in vacant units, renter-occupied units, and college education were associated with decreased open-closed. These results provide input for environmental justice research to identify inequalities and discover the distribution of environmental hazards among urban neighborhoods.

Tertiary butyl alcohol plumes in southern california groundwater from leaking underground storage tank sites

Tertiary butyl alcohol in the groundwater was evaluated using closed leaking underground storage tank sites in Southern California between 2016 and 2019. Tertiary butyl alcohol is not regulated and lacks a maximum contaminant level in California. The current level of 12 µg per liter in drinking water (notification level) is advisory and not enforceable. As high as 88% of sites during 2018–2019 fiscal year were closed with tertiary butyl alcohol higher than its notification level in groundwater. Twenty-five percent of the time, the maximum tertiary butyl alcohol concentrations in the groundwater at closure were higher than 2,300 µg per liter during 2016–2017, 7,600 µg per liter during 2017–2018, and 4,400 µg per liter during 2018–2019, respectively. The plume length of the maximum tertiary butyl alcohol increased from 649 feet in 2016 to 1,128 feet in 2019. Considering the proximity of drinking water wells to the leaking underground storage tank sites in California, this points to an increase risk of impact on the drinking water resources. Tertiary butyl alcohol remained above 12 µg/L in a substantial percentage (70% in 2016–1017, 72% in 2017–2018, and 88% in 2018–2019) of sites. Site closure practices at Los Angeles Regional Water Quality Control Board should be more stringent toward tertiary butyl alcohol contamination. Despite documented health hazards, tertiary butyl alcohol has not received sufficient attention from government agencies. The toxicological evaluation of tertiary butyl alcohol indicates significant human health concerns. Based upon the toxicological evidence, an MCL should be considered for tertiary butyl alcohol in drinking water.

Evaluation of tertiary butyl alcohol (TBA) impact on groundwater: application to California

Leaking underground storage tanks can contaminate the groundwater. Since the 1980s, California leaking underground storage tanks have released millions of gallons of petroleum containing tertiary butyl alcohol into the subsurface. This compound was banned in early 2000 due to human health concerns. The United States Environmental Protection Agency considers tertiary butyl alcohol an animal carcinogen and a potential human carcinogen. California has not established a maximum contaminant level for tertiary butyl alcohol. (1) Based on the documented health hazards, a maximum contaminant level should be developed for tertiary butyl alcohol in California. (2) The California Water Resources Control Board’s “Low Threat Closure Policy”, which is a tool to evaluate closure of leaking underground storage tank sites, does not require regulators to consider tertiary butyl alcohol contamination in soil or groundwater in their closure review. This practice should be revisited based upon tertiary butyl alcohol’s toxicity data, its biotransformation from methyl tertiary butyl ether, and its stability in the environment. This review summarizes toxicity, sources, and environmental transformation of tertiary butyl alcohol, aims to raise awareness regarding the magnitude of the tertiary butyl alcohol problem in groundwater, and urges California regulators to develop more stringent protocols for tertiary butyl alcohol treatment. The nine Regional Water Quality Control Boards regulate and oversee cleanup at leaking underground storage tank sites in California. This study will directly impact Regional Water Quality Control Boards regulatory practices and will help provide a framework for developing monitoring and cleanup strategy for tertiary butyl alcohol around the world.

“Business as Usual,” But What Is Usual?

“Business as Usual,” But What Is Usual?

Going Beneath the Surface: Petroleum Pollution, Regulation, and Health

This paper quantifies the health impacts of petroleum leaks from underground storage tanks, the effectiveness of tank regulation, and the role of information as a policy tool in the same setting. Exposure to a leaking underground storage tank during gestation increases both the probability of low birthweight and preterm birth by 7–8 percent. Compliance with regulations requiring the adoption of preventative technologies mitigated the entire effect of leak exposure on low birthweight, and information increased avoidance and moving among highly educated mothers. Back-of-the-envelope calculations suggest the health benefits of preventative regulations exceed the upgrade cost to facilities. (JEL I12, K32, L71, L78, Q35, Q51, Q53)

Control Measures on Groundwater Pollution through Leakages of Underground Storage Tanks of Filling Stations in Nigeria

Background: Groundwater pollution from leakages of Underground Storage Tanks is a global issue and has been significantly controlled and maintained by many developed countries in the last 30 years. The knowledge and practices used in containing this environmental issue can also be applied locally in Nigeria.&#x0D; Methods: This paper reviewed the environmental policies and strategies put in place by the United States of America and the statutory regulations in Nigeria to identify the possible causes of pollution from leaking underground storage tanks within the country in order to recommend applicable preventive and control measures.&#x0D; Results: Findings showed there are lots of regulations and laws to protect environmental resources in Nigeria which has led to establishment of different ministries, departments and agencies of government for implementation yet, a number of shortcomings can be traced to its inability to efficiently control leaking underground storage tanks in filling stations nationwide.&#x0D; Conclusion: However, necessary recommendations were made which could be applied by implementing minor preventive measures and procedures that will significantly curb this menace as achieved in other developed nations of the world.

An Approach for Passive Removal of Residual LNAPL from Groundwater

AbstractLight nonaqueous phase liquids (LNAPLs) are a problematic challenge for obtaining site closure or no further action remediation sites. The source of the LNAPLs varies from leaking underground petroleum storage tanks, to manufacturing facilities where oil leaks create LNAPL accumulations beneath factory floors. Active recovery using pumping or periodic vacuum recovery from wells or sumps is used for remediation, but usually has disappointing results when LNAPL reaccumulates to thicknesses exceeding the 0.01‐foot action level recognized by many states. This paper presents a simple passive approach for recovering persistent LNAPL using nonwoven hydrophobic oil absorbing cloth. The method used laboratory trials to assess physical properties of the cloth. Parameters observed and assessed included sorptive capacity and rate, buoyancy, and LNAPL wicking. It was determined that the cloth could be rolled and secured with cable ties for placement in the wells/sumps. Two placement designs were developed, one where rolled sorbent freely floated on the well/sump fluid surface and a second where the sorbent roll was placed in the fluid column at a fixed depth. Sorbents were then used at two manufacturing facilities where LNAPLs persisted for decades. In both instances, many wells/sumps were reduced to thicknesses below the action level in less than 2 months. In most wells, LNAPL did not reaccumulate. Where it did reaccumulate, it was less than 50% of the original thickness. Using laboratory‐derived recovery rates, cloth sorbents could be sized to minimize placement/recovery frequency while effectively recovering LNAPL.

The impacts of underground petroleum releases on a homeowner's decision to sell: A difference-in-differences approach

Actual and perceived damages from environmental disamenities can disrupt a utility maximizing household's otherwise optimal decision of when to sell their home. This study examines this relatively under-investigated topic with an empirical application to petroleum releases from leaking underground storage tanks, like those commonly found at gas stations. The ubiquity and relative homogeneity of this disamenity facilitates a difference-in-differences methodology. The results reveal that the timing of home sales is impacted by leak and cleanup events at these disamenities; leading to both selling sooner and delaying a sale, depending on the event, presence of the primary exposure pathway, and the quality of the home. The implications of these results are discussed.

A field study of nuclear magnetic resonance logging to quantify petroleum contamination in subsurface sediments

In a field study conducted in Pine Ridge, South Dakota, nuclear magnetic resonance (NMR) logging measurements were used to investigate an area of hydrocarbon contamination from leaking underground storage tanks. The NMR logging measurements are directly sensitive to hydrogen-bearing fluids in the sediments surrounding a well and can be used to estimate in situ fluid volumes. The relaxation time [Formula: see text] and diffusion coefficient [Formula: see text] of the fluids may be used to differentiate between signal from water and signal from contaminant, enabling the estimation of the hydrocarbon volume. In this study, NMR measurements were collected in two PVC-cased monitoring wells, with [Formula: see text] and [Formula: see text] measurements used together to detect a contaminant smear zone at both the wells. Although the contrast in [Formula: see text] between the fluids was found to be inadequate for fluid typing, the [Formula: see text] contrast between the contaminant and water in silt enabled the estimation of contaminant volumes. Using this technique, the vertical extent of the smear zone was found to be more than 3 m with up to 5 vol% contaminant in the sediments at one well and up to 9.5 vol% at the other well. Our work reveals that NMR logging can, under certain circumstances, be used to detect and quantify in situ contamination, but it also highlights the significant limitation that sediment and contaminant properties at many sites may result in insufficient contrast in [Formula: see text] and [Formula: see text].

Bioaugumentation Efficiency of Microbial Bacteria and Strategy for Its Recovery through Addition of NPK Fertilizers and the Study of Its Morphology

The study basically focuses on hydrocarbon contamination that is caused because of bacteria present in the soil. Transport Nagar Area in Jaipur is mostly covered with garages and hence surrounded by crude oil, petrol, diesel and other fractions of crude oil. Soil and ground water are polluted with diesel fuel from leaking underground storage tanks which happens as a result of accidental spills and leakage from pipelines which causes harm to the both flora and fauna. In the study conducted the treatment samples were observed with significant difference with the control. The microbial count was maintained in the range of 3.86*104- THBP per gram soil and 1.87*103- PDBP per gram soil. The highest bacterial growth was showed after 60 days with 40% NPK because of the presence of an inorganic nutrition, bacterial activity and as a result petroleum degradation was maximum.Int J Appl Sci Biotechnol, Vol 4(2): 233-235

Partitioning of Aromatic Constituents into Water from Jet Fuels.

A comprehensive study of the most commonly used jet fuels (i.e., Jet A-1 and JP-8) was performed to properly assess potential contamination of the subsurface environment from a leaking underground storage tank occurred in an airport. The objectives of this study were to evaluate the concentration ranges of the major components in the water-soluble fraction of jet fuels and to estimate the jet fuel-water partition coefficients (K fw) for target compounds using partitioning experiments and a polyparameter linear free-energy relationship (PP-LFER) approach. The average molecular weight of Jet A-1 and JP-8 was estimated to be 161 and 147g/mole, respectively. The density of Jet A-1 and JP-8 was measured to be 786 and 780g/L, respectively. The distribution of nonpolar target compounds between the fuel and water phases was described using a two-phase liquid-liquid equilibrium model. Models were derived using Raoult's law convention for the activity coefficients and the liquid solubility. The observed inverse, log-log linear dependence of the K fw values on the aqueous solubility were well predicted by assuming jet fuel to be an ideal solvent mixture. The experimental partition coefficients were generally well reproduced by PP-LFER.

Developing Life-Cycle Environmental Response Costs for Leaking Underground Storage Systems at Service Station Sites

Leaking underground storage tank systems at service stations have resulted in tens of thousands of petroleum releases and associated groundwater chemical plumes often extending hundreds of feet off-site. Technical and engineering approaches to assess and clean up releases from underground tanks, product lines, and dispensers using technologies such as soil vapor extraction, air sparging, biostimulation, and monitored natural attenuation are well understood and widely published throughout the literature. This article summarizes life-cycle environmental response costs typically encountered using site-specific cost estimation or metric-based cost categories considering the overall complexity of site conditions: (1) simple sites where response actions require smaller scale assessments and/or remediation and have limited or no off-site impacts; (2) average sites where response actions require larger scale assessments and/or remediation typical of petroleum releases; (3) complex sites where response actions require greater on-site and/or off-site remediation efforts; and (4) mega sites where petroleum plumes have impacted public or private water supplies or where petroleum vapors have migrated into occupied buildings. Associated cleanup cost estimates rely upon appropriate combinations of individual work elements and the duration of operation, maintenance, and monitoring activities. These cost estimates can be offset by state reimbursement funds, coverage in purchase agreements, and insurance policies. A case study involving a large service station site portfolio illustrates the range of site complexity and life-cycle environmental response costs. © 2014 Wiley Periodicals, Inc.

English

Volatile Organic Compounds (VOCs) are the most common subsurface environment contaminants usually in the form of Non-Aqueous Phase Liquids (NAPL) through Leaking Underground Storage Tanks (LUSTs) and pipelines, accidental spills, land disposal sites, and industrial waste impoundments. VOCs are toxic, mutagenic and carcinogenic. Hence, VOCs in subsoil pose a serious threat of groundwater contamination. Organic compounds, owing to their persistence and volatility, present unique environmental problems in the vadose zone of soils. The uncertainty in transport mechanisms and subsoil environment pose a serious challenge in developing transport model for VOC compounds. Apart from advection and dispersion, VOC also undergo several complex chemical reactions such as adsorption, degradation, volatilization and ionic exchange. The transport mechanisms and transport modeling studies for VOCs are largely based on extensive field studies and relevant laboratory experiments. The focus here is to review the role of transport mechanisms and modeling aspects of organic compounds in petroleum fuels and other such liquids and liquid wastes that have the potential to migrate through subsoil to groundwater and also to atmosphere by vapor diffusion.

Mineral transformation controls speciation and pore-fluid transmission of contaminants in waste-weathered Hanford sediments

Portions of the Hanford Site (WA, USA) vadose zone were subjected to weathering by caustic solutions during documented releases of high level radioactive waste (containing Sr, Cs and I) from leaking underground storage tanks. Previous studies have shown that waste-sediment interactions can promote variable incorporation of contaminants into neo-formed mineral products (including feldspathoids and zeolites), but processes regulating the subsequent contaminant release from these phases into infiltrating background pore waters remain poorly known. In this paper, reactive transport experiments were conducted with Hanford sediments previously weathered for one year in simulated hyper-alkaline waste solutions containing high or low 88Sr, 127I, and 133Cs concentrations, with or without CO2(aq). These waste-weathered sediments were leached in flow-through column experiments with simulated background pore water (characteristic of meteoric recharge) to measure contaminant release from solids formed during waste-sediment interaction. Contaminant sorption–desorption kinetics and mineral transformation reactions were both monitored using continuous-flow and wet-dry cycling regimes for ca. 300 pore volumes. Less than 20% of contaminant 133Cs and 88Sr mass and less than 40% 127I mass were released over the course of the experiment. To elucidate molecular processes limiting contaminant release, reacted sediments were studied with micro- (TEM and XRD) and molecular- (Sr K-edge EXAFS) scale methods. Contaminant dynamics in column experiments were principally controlled by rapid dissolution of labile solids and competitive exchange reactions. In initially feldspathoidic systems, time-dependent changes in the local zeolitic bonding environment observed with X-ray diffraction and EXAFS are responsible for limiting contaminant release. Linear combination fits and shell-by-shell analysis of Sr K-edge EXAFS data revealed modification in Sr–Si/Al distances within the zeolite cage. Wet-dry cycling did not affect significantly molecular-scale transformations relative to continuous-flow controls. Results indicate that contaminants bound to the solid phase in distinct micro- and molecular-scale coordinative environments can generate similar macro-scale release behaviors, highlighting the need for multi-scale interrogations to constrain mechanisms of reactive transport. Data also indicate that weathering-induced change in ion exchange selectivity coefficients should be incorporated in simulations of contaminant release from caustic high-level radioactive waste impacted sediments.

Assessment of Spatial Disparities in the Burden of Underground Storage Tanks in Maryland (2001–2011)

Abstract The presence of leaking underground storage tanks (LUST) may present environmental justice (EJ) concerns including groundwater contamination for communities with a number of USTs, other environmental hazards, and poor infrastructure. The purpose of this study is to assess ten years of residential LUST exposure data in Maryland across areas with varying sociodemographic composition. Methods: We linked ten years of site-specific LUST remediation data with 2010 Census data. Simple linear regression was conducted using R to predict increases in proximity to LUSTs based on independent sociodemographic variables as well as diversity and deprivation indices. Results: Consistently, across the state, census tracts with a higher composition of white residents demonstrated more resistance to decaying distance between adjacent LUSTs (Beta=0.003; p<0.05) than census tracts with higher composition of non-white (Beta=−0.003; p<0.05) and similar trends for % poverty, % < than high school (HS) education, % homes ...

Leaking Underground Storage Tanks and Environmental Injustice: Is There a Hidden and Unequal Threat to Public Health in South Carolina?

There are approximately 590,000 underground storage tanks (USTs) nationwide that store petroleum or hazardous substances. Many of these tanks are leaking, which may increase the risk of exposure to contaminants that promote health problems in host neighborhoods. Within this study, we assessed disparities in the spatial distribution of leaking underground storage tanks (LUSTs) based on socioeconomic status (SES) and race/ethnicity in South Carolina (SC). Chi-square tests were used to evaluate the difference in the proportion of populations who host a LUST compared to those not hosting a LUST for all sociodemographic factors. Linear regression models were applied to examine the association of distance to the nearest LUST with relevant sociodemographic measures. As percent black increased, the distance (both in kilometers and miles) to the nearest LUST decreased. Similar results were observed for percent poverty, unemployment, persons with less than a high school education, blacks in poverty, and whites in poverty. Furthermore, chi-square tests indicated that blacks or non-whites or people with low SES were more likely to live in LUST host areas than in non-host areas. As buffer distance increased, percent black and non-white decreased. SES variables demonstrated a similar inverse relationship. Overall, burden disparities exist in the distribution of LUSTs based on race/ethnicity and SES in SC.

Vapor Intrusion Screening at Petroleum UST Sites

AbstractDetailed site investigations to assess potential inhalation exposure and risk to human health associated with the migration of petroleum hydrocarbon vapors from the subsurface to indoor air are frequently undertaken at leaking underground storage tank (UST) sites, yet documented occurrences of petroleum vapor intrusion are extremely rare. Additional assessments are largely driven by low screening‐level concentrations derived from vapor transport modeling that does not consider biodegradation. To address this issue, screening criteria were developed from soil‐gas measurements at hundreds of petroleum UST sites spanning a range of environmental conditions, geographic regions, and a 16‐year time period (1995 to 2011). The data were evaluated to define vertical separation (screening) distances from the source, beyond which, the potential for vapor intrusion can be considered negligible. The screening distances were derived explicitly from benzene data using specified soil‐gas screening levels of 30, 50, and 100 µg/m3 and nonparametric Kaplan‐Meier statistics. Results indicate that more than 95% of benzene concentrations in soil gas are ≤30 µg/m3 at any distance above a dissolved‐phase hydrocarbon source. Dissolved‐phase petroleum hydrocarbon sources are therefore unlikely to pose a risk for vapor intrusion unless groundwater (including capillary fringe) comes in contact with a building foundation. For light nonaqueous‐phase liquid (LNAPL) hydrocarbon sources, more than 95% of benzene concentrations in soil gas are ≤30 µg/m3 for vertical screening distances of 13 ft (4 m) or greater. The screening distances derived from this analysis are markedly different from 30 to 100 ft (10 to 30 m) vertical distances commonly found cited in regulatory guidance, even with specific allowances to account for uncertainty in the hydrocarbon source depth or location. Consideration of these screening distances in vapor intrusion guidance would help eliminate unnecessary site characterization at petroleum UST sites and allow more effective and sustainable use of limited resources.

From the Editors

From the Editors

The impacts of pollution and exposure pathways on home values: A stated preference analysis

Hedonic property value methods are an attractive non-market valuation technique. In practice, however, researchers are often forced to make untested assumptions regarding the public's perceptions of the environmental commodity being studied. Stated preference methods offer an opportunity to examine how home values are affected when researchers know exactly what is being valued. A stated preference study is conducted to investigate how people value environmental quality, by measuring impacts on home values from a leaking underground storage tank (LUST). The study incorporates two experimental treatments, expressing environmental risks in terms of (i) the presence of an exposure pathway, and (ii) pollution concentrations. This mimics information provided to Maryland households whose groundwater is actually impacted by a LUST.The questionnaire is administered to a convenience sample of Maryland residents. Within sample comparisons of the experimental treatments reveal that even when the groundwater at a home is not contaminated, respondents believe home prices decrease 18% to 24%. Prices decrease further once pollution levels exceed the regulatory standard, and an exposure pathway is present. Respondents seem capable of interpreting pollution information, and believe prices are impacted in ways consistent with economic theory. Future research to further bridge the gap between methodologies is discussed.