Natural source zone depletion of LNAPL: A critical review supporting modelling approaches

Natural source zone depletion (NSZD) of light non-aqueous phase liquids (LNAPLs) includes partitioning, transport and degradation of LNAPL components. NSZD is being considered as a site closure option during later stages of active remediation of LNAPL contaminated sites, and where LNAPL mass removal is limiting. To ensure NSZD meets compliance criteria and to design enhanced NSZD actions if required, residual risks posed by LNAPL and its long term behaviour require estimation. Prediction of long-term NSZD trends requires linking physicochemical partitioning and transport processes with bioprocesses at multiple scales within a modelling framework. Here we expand and build on the knowledge base of a recent review of NSZD, to establish the key processes and understanding required to model NSZD long term. We describe key challenges to our understanding, inclusive of the dominance of methanogenic or aerobic biodegradation processes, the potentially changeability of rates due to the weathering profile of LNAPL product types and ages, and linkages to underlying bioprocesses. We critically discuss different scales in subsurface simulation and modelling of NSZD. Focusing on processes at Darcy scale, 36 models addressing processes of importance to NSZD are investigated. We investigate the capabilities of models to accommodate more than 20 subsurface transport and transformation phenomena and present comparisons in several tables. We discuss the applicability of each group of models for specific site conditions

Hyperspectral Analysis of Oil and Oil-Impacted Soils for Remote Sensing Purposes

While conventional multispectral sensors record the radiometric signal only at a handful of wavelengths, hyperspectral sensors measure the reflected solar signal at hundreds contiguous and narrow wavelength bands, spanning from the visible to the infrared. Hyperspectral images provide ample spectral information to identify and distinguish between spectrally similar (but unique) materials, providing the ability to make proper distinctions among materials with only subtle signature differences. Hyperspectral images show hence potentiality for proper discrimination between oil slicks and other natural phenomena (look-alike); and even for proper distinctions between oil types. Additionally they can give indications on oil volume. At present, many airborne hyperspectral sensors are available to collect data, but only two civil spaceborn hyperspectral sensors exist as technology demonstrator: the Hyperion sensor on NASA’s EO-1 satellite and the CHRIS sensor on the European Space Agency’s PROBA satellite. Consequently, the concrete opportunity to use spaceborn hyperspectral remote sensing for operational oil spill monitoring is yet not available. Nevertheless, it is clear that the future of satellite hyperspectral remote sensing of oil pollution in the marine/coastal environment is very promising. In order to correctly interpret the hyperspectral data, the retrieved spectral signatures must be correlated to specific materials. Therefore specific spectral libraries, containing the spectral signature of the materials to be detected, must be built up. This requires that highly accurate reflected light measurements of samples of the investigated material must be performed in the lab or in the field. Accurate measurements of the spectral reflectance of several samples of oil-contaminated soils have been performed in the laboratory, in the 400-2500 nm wavelength range. Samples of the oils spilt from the Erika and the Prestige tankers during the major accidents of 1999 and 2002 were also collected and analyzed in the same spectral range, using a portable spectrophotometer. All measurements showed the typical absorption features of hydrocarbon-bearing substances: the two absorption peaks centered at 1732 and 2310 nm.JRC.G.3-Agricultur

The 22nd Annual International Conference on Soils, Sediments and Water

Conference at a Glance Monday, October 16, 2006 Workshop #1: 8:30am - 5:00pm Workshop #2: 9:00am - 5:00pm Workshop #3: 10:00am - 5:00pm Workshops #4, 5 & 6: 1:00pm - 5:00pm Workshop #10: 2:00 - 5:00pm Workshop #1: Evaluating Monitored Natural Attenuation of MTBE and TBA Workshop #2: Getting to Closure at LNAPL Sites Workshop #3: In-Situ Chemical Oxidation Workshop Workshop #4: The Role of Anaerobic Biodegradation Processes in Passive and Enhanced Monitored Natural Attenuation Programs Workshop #5: The 2006 MCP Audit- A Case Study Approach Workshop #6: Integrating the Remediation Strategy into the Lifecycle of a Contaminated Sediments Project Workshop #10: Environmental Fate of Hydrocarbons in Soils and Groundwater Tuesday, October 17, 2006 Morning 8:30am - 9:00am Conference Welcome and Overview 9:00am - Noon Sessions are concurrent Session 1: Risk Assessment Session 2: Site Assessment Session 3: Legal/Regulatory Session 4: Heavy Metals Session 5: Combining Chemical and Biological Technologies for Soil and Groundwater Remediation Afternoon 1:30pm - 5:30pm Sessions are concurrent Session 1: Environmental Biotechnology Session 2: Analysis Session 3: Ozone Remedial Barrier and Clean-up systems for Fuel and Solvent Spills Session 4: Emerging Contaminants Session 5: Phytoremediation Poster Session 4:00 - 6:00pm, Exhibit Area, First Floor, Campus Center Social 4:30-6:00pm, Exhibit Area, First Floor, Campus Center Workshops Evening, 7:00 - 10:00pm Workshop #7: Applied Chemical Fingerprinting in Environmental Forensics Workshop #8: In-Situ Thermal Remediation Wednesday, October 18, 2006 Morning 8:30am - Noon Sessions are concurrent Session 1: Environmental Benefits and Risks of Nanomaterials Session 2: Chemical Oxidation Session 3: Environmental Forensics *Session 4A: Oxygenates and Public Water Supplies *Session 4B: Evaluating and Management of Small Releases from USTs Afternoon 1:30pm - 5:30pm Sessions are concurrent Session 1: Remediation Session 2: Natural Resource Damage Assessments: Integrating Remediation and Restoration Session 3: Perchlorate *Session 4A: Oxygenate Biodegradation *Session 4B: Ethanol Fuels *Please note: Sessions 4A and 4Bmorning and afternoon will run concurrently with the other sessions, BUT the presentation times will not be the same as presentation times for Sessions 1, 2 and 3. Please consult the final program for presentation times Poster Session 4:00 - 6:00pm, Exhibit Area, First Floor, Campus Center Social 4:30-6:00pm, Exhibit Area, First Floor, Campus Center Workshops Evening, 7:00 - 10:00pm Workshop #9: Down-Gradient Property Status: Practices and Pitfalls Workshop #10 has been moved to Monday, October 16, 2006, from 2:00 - 5:00pm. Thursday, October 19, 2006 Morning 8:30am -Noon Sessions are concurrent Session 1: Vapor Intrusion Session 2: Implementing Aggressive Remediation Strategies Session 3: Bioremediation Session 4: Contaminated Sites Research in Canada & the Contaminated Sites Action Plan Afternoon 1:30pm – 5:30pm Sessions are concurrent Session 1: Sediments Session 2: Arsenic Session 3A: Brownfields Session 3B: Environmental Fate Session 4: Pesticide

Towards characterizing LNAPL remediation endpoints

Remediating sites contaminated with light non-aqueous phase liquids (LNAPLs) is a demanding and often prolonged task. It is vital to determine when it is appropriate to cease engineered remedial efforts based on the long-term effectiveness of remediation technology options. For the first time, the long term effectiveness of a range of LNAPL remediation approaches including skimming and vacuum-enhanced skimming each with and without water table drawdown was simulated through a multi-phase and multi-component approach. LNAPL components of gasoline were simulated to show how component changes affect the LNAPL\u27s multi-phase behaviour and to inform the risk profile of the LNAPL. The four remediation approaches along with five types of soils, two states of the LNAPL specific mass and finite and infinite LNAPL plumes resulted in 80 simulation scenarios. Effective conservative mass removal endpoints for all the simulations were determined. As a key driver of risk, the persistence and mass removal of benzene was investigated across the scenarios. The time to effectively achieve a technology endpoint varied from 2 to 6 years. The recovered LNAPL in the liquid phase varied from 5% to 53% of the initial mass. The recovered LNAPL mass as extracted vapour was also quantified. Additional mass loss through induced biodegradation was not determined. Across numerous field conditions and release incidents, graphical outcomes provide conservative (i.e. more prolonged or greater mass recovery potential) LNAPL remediation endpoints for use in discussing the halting or continuance of engineered remedial efforts

Hazardous Waste Management

This book presents a comprehensive overview of hazardous waste and hazardous waste management. It describes the various types and constituents of hazardous waste, discusses hazardous waste management techniques and technologies, and highlights techno-economic considerations and key issues in remediation. It is a useful resource for waste management and treatment professionals, chemical engineers, technicians, medical professionals, and environmental regulators as well as students studying hazardous waste management, environmental engineering, and environmental science