David J. Lampert

Assessing the Effectiveness of Thin-Layer Sand Caps for Contaminated Sediment Management through Passive Sampling

The effectiveness of thin-layer sand capping for contaminated sediment management (capping with a layer of thickness comparable to the depth of benthic interactions) is explored through experiments with laboratory-scale microcosms populated with the deposit-feeding oligochaete, Ilyodilus templetoni. Passive sampling of pore water concentrations in the microcosms using polydimethylsiloxane (PDMS)-coated fibers enabled quantification of high-resolution vertical concentration profiles that were used to infer contaminant migration rates and mechanisms. Observed concentration profiles were consistent with models that combine traditional contaminant transport processes (sorption-retarded diffusion) with bioturbation. Predictions of bioaccumulation based on contaminant pore water concentrations within the surface layer of the cap correlated well with observed bioaccumulation (correlation coefficient of 0.92). The results of this study show that thin-layer sand caps of contaminated sediments can be effective at reducing the bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) provided the thickness of the cap layer exceeds the depth of organism interaction with the sediments and the pore water concentrations within the biologically active zone remain low (e.g., when molecular diffusion controls transport from the underlying sediment layer).

Wells to wheels: water consumption for transportation fuels in the United States.

The sustainability of energy resources such as transportation fuels is increasingly connected to the consumption of water resources. Water is required for irrigation in the development of bioenergy, reservoir creation in hydroelectric power generation, drilling and resource displacement in petroleum and gas production, mineral extraction in mining operations, and cooling and processing in thermoelectric power generation. Vehicles powered by petroleum, electricity, natural gas, ethanol, biodiesel, and hydrogen fuel cells consume water resources indirectly through fuel production cycles, and it is important to understand the impacts of these technologies on water resources. Previous investigations of water consumption for transportation fuels have focused primarily on key processes and pathways, ignoring the impacts of many intermediate, inter-related processes used in fuel production cycles. Herein, the results of a life cycle analysis of water consumption for transportation fuels in the United States using an extensive system boundary that includes the water embedded in intermediate processing and transportation fuels are presented. The Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation (GREET) model provides a comprehensive framework and system boundary for transportation fuel analysis in the United States. GREET was expanded to include water consumption and used to compare the water consumed per unit energy and per km traveled in light-duty vehicles. Many alternative fuels were found to consume larger quantities of water on a per km basis than traditional petroleum pathways, and it is therefore important to consider the implications of transportation and energy policy changes on water resources in the future.

An Analytical Modeling Approach for Evaluation of Capping of Contaminated Sediments

An analytical design tool is developed to predict performance of a cap for containment of contaminated sediments. Transient conditions within a cap can be modeled by advection, diffusion, and reaction within the typically homogeneous chemical isolation layer for which analytical models exist. After contaminant penetration of the chemical isolation layer, a steady state model is proposed that incorporates pore water advection and diffusion, sediment erosion and deposition, sediment re-working and pore water pumping via bioturbation, and reaction. The steady state model allows the complexities of the biologically active layer to be considered while maintaining an analytical form for convenient and rapid evaluation. In this paper, the model framework, behavior, and limitations are presented.

Internal and external transport significance for predicting contaminant uptake rates in passive samplers

A critical element in the application of passive sampling devices for estimating in situ the concentrations of contaminants in pore water of sediments is predicting the rate of uptake within the device. Herein, we demonstrate the relative importance of internal and external mass transport processes for sampling devices and show that external processes control the kinetics in many instances. As such uptake rates are closely related to the surface area to volume ratio of the sampling device and site-specific transport conditions. Models based on sorption-related molecular diffusion provide an upper bound on equilibrium times. The essential model parameters and corresponding kinetics at a site with more substantial mixing can be inferred using time series of sampler concentrations, concentrations in samplers with different geometry, or concentrations of performance reference compounds.

Comment on "Comparison of Water Use for Hydraulic Fracturing for Unconventional Oil and Gas versus Conventional Oil".

Unconventional Oil and Gas versus Conventional Oil” T unconventional extraction of oil and gas from shale formations has recently become economical due to advances in hydraulic fracturing and horizontal drilling technologies. A byproduct of this new production is the consumption of water associated with hydraulic fracturing technology. Scanlan et al. (2014) analyzed the consumption of water resources associated with new unconventional production of oil and gas from the Bakken formation in Eastern Montana and Western North Dakota and the Eagle Ford Formation in South Texas. In the manuscript, the authors estimated ratios of the water consumed to oil produced (WORs) in new shale plays and compared these estimates to WORs from conventional production. The conclusion drawn is that the WORs of unconventional shale oil plays “are within the lower range of those for conventional oil production, considering the well lifetime.” The comparisons made in the paper fail to account for the large differences in the maturity of conventional and unconventional wells and thus unfairly characterize new shale oil plays as having lower water intensity than conventional operations. Recovery operations from conventional wells typically progress through several stages of development as the well matures. Following well construction, the reservoir produces petroleum with little to no external stimulus. After the primary production period, water is typically injected during a secondary water flooding period that is often followed by a tertiary recovery period that may utilize chemicals, heat, and/or gases in addition to water to maintain reservoir pressure. The comparison of current levels of water consumption in shale plays associated solely with well development and primary production to water consumption from mature wells utilizing secondary and tertiary recovery technologies is unreasonable, particularly in the context of estimated ultimate recoveries. At this time it is unclear whether enhanced recovery technologies will be economical in shale formations as they have been in other formations because of lower permeability; however, water flooding and other enhanced recovery technologies for shale are under investigation. CO2 injection appears particularly viable and may have lower water intensity; however, gas injection is often accompanied by water injection and the literature indicates higher WORs for CO2 injection than water flooding. In any case, the cover art and several of the figures presented by Scanlan et al. (2014) compare water consumption estimates for primary, secondary, and tertiary recovery stages from conventional wells to production solely from the primary period in these new shale plays. As such they unfairly portray shale oil recovery as having lower water intensity across its lifecycle than recovery from conventional operations. The WORs for conventional recovery presented by Scanlan et al. (2014) are derived primarily from Wu and Chiu (2011), who compiled literature values for different technologies and estimated a US average injection of 8 gallons of water per gallon crude oil produced consisting of 2.1−5.4 gallons makeup water with the remainder coming from recycled produced water from the formation. Figure 1 compares the literature values of water injections, makeup injection water requirements, and

Development of an open-source software package for watershed modeling with the Hydrological Simulation Program in Fortran

The Hydrological Simulation Program in Fortran (HSPF) is used extensively for the assessment of water quantity and water quality issues. Herein, the development of an open-source, cross-platform package for building input files, performing simulations, postprocessing and calibrating HSPF models using the Python Programming Language is presented. The flexible nature of Python opens the door to automated preprocessing and calibration routines, visualization, multiprocessing, and larger-scale model development. The software is applied using Python scripts, which provides a flexible mechanism for learning and applying HSPF. An example application of the software was used to build a calibrated HSPF model the Hunting Creek watershed within the Patuxent River Basin, Maryland, USA, which is the example application distributed with the HSPF calibration software package HSPExp. A script of a few hundred lines was used to build a calibrated model comparable to HSPExp in a simulation time of less than two hours. Developed an operating system-independent interface to the subroutines for the Hydrological Simulation Program in Fortran (HSPF) in the Python Programming Language.Developed an open-source suite of software tools for gathering data and building input files for HSPF using Python scripting.Demonstrated the application of the software tools for automatically building a baseline HSPF model using publically-available data on the World Wide Web.Demonstrated automatic calibration using a parallel processing routine that performed favorably compared to existing software.

Capping for Remediation of Contaminated Sediments

The historical release of contaminants into the environment has generated a legacy of contaminated sites throughout the world. For years, the sediments in water bodies adjoining these pollution sources served as sinks for contaminants, particularly hydrophobic organic compounds (HOCs) and heavy metals. Many of these original sources have been eliminated, but the sediments that formerly served as a pollutant sink now serve as sources of contamination and residual environmental risk. Assessment and remediation of these contaminated sediment sites have been the subject of much scientific analysis, public debate and technological innovation (NRC, 2001).There are few economically viable options for management of contaminated sediments. Capping sediments with a layer of clean material is one of few alternatives with a proven record of success for sediment remediation. This chapter is intended to describe the tools and techniques that are applicable for 55 assessment, design, implementation and monitoring of capping as a remedy for contaminated sediment sites.

A software tool for simulating contaminant transport and remedial effectiveness in sediment environments

Abstract Sediments have often acted as sinks for contaminants that possess strong affinity for solids near historical pollution sources. Mathematical models describing the evolution of contaminant concentrations in sediment environments provide a scientific basis for decision support and remediation design. Herein, novel software (CapSim) is introduced including processes relevant to natural attenuation and in-situ treatment and containment (capping). The tool has been used as a basis for remedial design at a number of sites throughout the United States. CapSim is built on the concept of an arbitrary number of layers that each exhibit traditional porous media transport processes including sorption (linear and non-linear, transient or local equilibrium), advection, diffusion, dispersion, multicomponent linked reactions and, critically, processes specific to the sediment-water interface including bioturbation of both solids and porewater, deposition, consolidation, and interaction with the overlying surface water. A summary of recent applications and selected simulations of key features are presented.

Emerging Research Needs for Assessment and Remediation of Sediments Contaminated with Per- and Poly-fluoroalkyl Substances

Like many other classes of synthetic organic chemicals, perand poly-fluoroalkyl substances (PFAS) possess unique properties that make them simultaneously beneficial for economic purposes but also detrimental to environmental quality. PFAS have been used extensively in food packaging, stain repellants, polishes, waxes, fire-fighting foams, and electronics manufacturing since their manufacture began over 50 years ago. Following the discovery of organic fluorides in human tissues in the 1960s, toxicological research has linked PFAS to reproductive and developmental effects in lab studies of rats and other mammals. Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) have received the majority of the attention in the scientific literature [1–3], but other PFAS present unknown risks in need of further assessment. Concerns about the risks of PFAS exposure from sources in the environment have recently increased following new evidence of their remarkable stability, bioaccumulation propensity, and potential health risks.