Tracking NSZD mass removal rates over decades: Site-wide and local scale assessment of mass removal at a legacy petroleum site

Davis, Gordon B.; Rayner, J. C. W.; Donn, Michael J.; Johnston, Colin D.; Lukatelich, R; King, Andrew; Bastow, Trevor P.; Bekele, Elise

doi:10.1016/j.jconhyd.2022.104007

Cited by 15 publications

(13 citation statements)

References 35 publications

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“…4b shows NSZD rate estimates calculated from the O 2 concentration data set in Fig. 4a for data from each probe depth, and assuming a constant diffusion coefficient over this time period (2.3 × 10 –6 m 2 /s for oxygen, being the minimum proposed by Davis et al 2022 ). In reality, the diffusion coefficient will vary based on variations in soil moisture content, but such refinements are not included here.…”

Section: Nszd Monitoring and Prediction As An Example Case Studymentioning

confidence: 97%

“…Soil gas: Gases in shallow soils have been deemed critical for agricultural purposes (Gliński and Stępniewski 1985 ) but gained importance as a shallow survey tool to map subsurface volatile organic compounds (VOCs) as a measure of subsurface contamination in soil and groundwater (Marrin and Kerfoot 1988 ; Barber et al 1990a ; Davis et al 1991 ) and for contaminant vapour risks (Davis et al 2021 ). Recently, soil gas sampling has become a strong focus for quantifying the rate of natural source zone depletion of petroleum light nonaqueous phase liquids (LNAPLs) in the subsurface (Sookhak Lari et al 2017 ; Davis et al 2022 ), since VOC and oxygen consumption, and methane and carbon dioxide production are strong indicators of LNAPL biodegradation processes and rates (Garg et al 2017 ; Sookhak Lari et al 2019 ).…”

Section: Framing Where We Are Atmentioning

confidence: 99%

“…For some contaminants and systems, this may rely on considerable prior research and knowledge. For example, there has been decades of research on petroleum hydrocarbons and solvents in the subsurface (Davis et al 2022 ), but significantly less on PFAS compounds and their additional air–water interfacial behaviours (Brusseau 2018 ). Ongoing research will create deeper understanding and improved CSMs to enable focused efforts and automated sensing.…”

Section: Possible Way Forwardmentioning

confidence: 99%

“…As such the conceptualization of LNAPL NSZD processes are largely in place after decades of research—so addresses Criteria 1, which is the need for deep understanding. Additionally, the field site is the BP Kwinana site as described in Davis et al ( 2022 ), which has a mature CSM, with investigations spanning decades (e.g., Davis et al 1998 ). Petroleum hydrocarbon masses across the site have been reasonably quantified and the depth distribution of LNAPL within the shallow sandy soil profile and in the zone of water table fluctuation 2–5 m below ground surface.…”

Section: Nszd Monitoring and Prediction As An Example Case Studymentioning

confidence: 99%

“…For example, based on the rates in Fig. 4b , and taking the specific mass at the site to be in the range of 15–68 kg/m 2 (Davis et al 2022 ), Fig. 4b could instead depict the estimated time to degrade all the aviation gasoline NAPL resident in the subsurface (the ranges here would be < 1–35 years with an approximate average of say 5–15 years)—a key measure for regulators and industry.…”

Section: Nszd Monitoring and Prediction As An Example Case Studymentioning

confidence: 99%

See 4 more Smart Citations

Advancing “Autonomous” sensing and prediction of the subsurface environment: a review and exploration of the challenges for soil and groundwater contamination

Davis

Rayner

Donn

2023

Environ Sci Pollut Res

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Can we hope for autonomous (self-contained in situ) sensing of subsurface soil and groundwater pollutants to satisfy relevant regulatory criteria? Global advances in sensors, communications, digital technologies, and computational capacity offer this potential. Here we review past efforts to advance subsurface investigation techniques and technologies, and computational efforts to create a digital twin (representation) of subsurface processes. In the context of the potential to link measurement and sensing to a digital twin computation platform, we outline five criteria that might make it possible. Significant advances in sensors based on passive measurement devices are proposed. As an example of what might be achievable, using the five criteria, we describe the deployment of online real-time sensors and simulations for a case study of a petroleum site where natural source zone depletion (NSZD) is underway as a potential biodegradation management option, and where a high-quality conceptual site model is available. Multiple sensors targeting parameters (major gases and temperature influenced by soil moisture) relevant to the subsurface NSZD biodegradation processes are shown to offer the potential to map subsurface processes spatially and temporally and provide continuous estimates of degradation rates for management decisions, constrained by a computational platform of the key processes. Current limitations and gaps in technologies and knowledge are highlighted specific to the case study. More generally, additional key advances required to achieve autonomous sensing of subsurface soil and groundwater pollutants are outlined.

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Section: Nszd Monitoring and Prediction As An Example Case Studymentioning

confidence: 97%

Section: Framing Where We Are Atmentioning

confidence: 99%

Section: Possible Way Forwardmentioning

confidence: 99%

Section: Nszd Monitoring and Prediction As An Example Case Studymentioning

confidence: 99%

Section: Nszd Monitoring and Prediction As An Example Case Studymentioning

confidence: 99%

See 3 more Smart Citations

Advancing “Autonomous” sensing and prediction of the subsurface environment: a review and exploration of the challenges for soil and groundwater contamination

Davis

Rayner

Donn

2023

Environ Sci Pollut Res

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Long‐term evaluation of hydrocarbon degradation rates within the source zone under natural and enhanced attenuation for site closure purposes

Schneider,

Bortolassi,

Soriano

et al. 2024

Remediation Journal

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Despite addressing the cleanup of petroleum hydrocarbon contamination plumes in groundwater, challenges with site closure persist due to the ongoing long‐term contaminant release from source zones. Thus, source zone monitoring even in the presence of residual light nonaqueous‐phase liquid (LNAPL) is mandated by many countries' regulatory agencies before site closure. In this study, four independent controlled‐release sites, each containing a particular fraction of ethanol in gasoline, that is, 10%, 24%, 25%, and 85% (v/v), were subjected to monitored natural attenuation (MNA) alone (E24 and E85), and with nitrate (E25) and sulfate (E10) biostimulation at the vicinity of the source zone. To the best of the authors' knowledge, this is the longest controlled gasohol release monitoring study performed to date at the source zone for site closure (nearly 18 years of monitoring). Both natural source zone depletion and biostimulation were found to reduce benzene concentrations to acceptable remediation target levels according to environmental regulatory councils. Benzene biodegradation rates (λs) were one order of magnitude higher than those reported in the literature for diluted concentrations in groundwater plumes. The decay rate of benzene varied between 0.45 and 1.75/year and was strongly influenced by the mass of ethanol. Compared to biostimulation with nitrate (half‐life of 1.52 years), MNA alone resulted in faster benzene removal rates (half‐life of 0.96 years). Anaerobic biostimulation with sulfate had negligible effects on benzene, toluene, ethylbenzene, and xylene (o‐, m‐, and p‐xylene [BTEX]) biodegradation compared to natural attenuation alone. The highest ethanol concentration (E85) led to faster benzene removal (with a half‐life of 0.40 years), which was even higher than MNA under lower ethanol concentrations (E24). Benzene half‐life was 2.2‐fold slower in the site with the lowest ethanol (E10) compared to E85, indicating that the negative effects of ethanol on BTEX biodegradation appeared to be short‐lived and may need to be re‐evaluated over the long term. Benzene decay rates were approximately six times slower in the source zone than the rates obtained for groundwater plumes, emphasizing the importance of targeting the LNAPL after plume retreat. The study's findings can assist practitioners in better predicting the lines of evidence for BTEX bioremediation and remediation cleanup times at a lower cost in the presence of ethanol, as well as providing guidance for determining whether biostimulation is necessary to expedite source zone remediation for site closure.

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Incorporating Natural Source Zone Depletion (NSZD) into the Site Management Strategy

Palaia,

Park

2023

Environmental Contamination Remediation and Management

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This chapter summarizes three petroleum remediation case study sites that incorporated natural source zone depletion (NSZD) into their site management strategy. The sites include: a light petroleum non-aqueous phase liquid (NAPL) pipeline release in an arid climate that transitioned to an NSZD-based monitored natural attenuation (MNA) remedy after several traditional remedial actions; a former refinery in a temperate climate that incorporated NSZD with phytoremediation; and a former industrial petrochemical facility in a tropical climate with waste dense petroleum hydrocarbon NAPL that transitioned to NSZD after several decades of groundwater extraction and treatment. The narratives provide examples of how NSZD was used as an effective and sustainable/resilient management option. Key points related to the use of NSZD on a broader range of site conditions are highlighted. The importance of acknowledging, accounting, and incorporating NSZD into remedies is emphasized because significant depletion rates are frequently observed to occur at petroleum NAPL release sites. The chapter demonstrates how NSZD can be incorporated into a conceptual site model and the implemented remedy. It provides details on the importance of site risk profile and regulatory framework as well as lines of evidence to support transition to a MNA remedy inclusive of NSZD.

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Tracking NSZD mass removal rates over decades: Site-wide and local scale assessment of mass removal at a legacy petroleum site

Cited by 15 publications

References 35 publications

Advancing “Autonomous” sensing and prediction of the subsurface environment: a review and exploration of the challenges for soil and groundwater contamination

Advancing “Autonomous” sensing and prediction of the subsurface environment: a review and exploration of the challenges for soil and groundwater contamination

Long‐term evaluation of hydrocarbon degradation rates within the source zone under natural and enhanced attenuation for site closure purposes

Incorporating Natural Source Zone Depletion (NSZD) into the Site Management Strategy

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