Expedited Site Characterization Research Articles

Assessment of Intrinsic Bioremediation of a Coal‐Tar‐Affected Aquifer Using Two‐Dimensional Reactive Transport and Biogeochemical Mass Balance Approaches

Expedited site characterization and groundwater monitoring using direct-push technology and conventional monitoring wells were conducted at a former manufactured gas plant site. Biogeochemical data and heterotrophic plate counts support the presence of microbially mediated remediation. By superimposing solutions of a two-dimensional reactive transport analytical model, first-order degradation rate coefficients ((day-1) ) of various compounds for the dissolved-phase plume were estimated (i.e., benzene [0.0084], naphthalene [0.0058], and acenaphthene [0.0011]). The total mass transformed by aerobic respiration, nitrate reduction, and sulfate reduction around the free-phase coal-tar dense-nonaqueous-phase-liquid region and in the plume was estimated to be approximately 4.5 kg/y using a biogeochemical mass-balance approach. The total mass transformed using the degradation rate coefficients was estimated to be approximately 3.6 kg/y. Results showed that a simple two-dimensional analytical model and a biochemical mass balance with geochemical data from expedited site characterization can be useful for rapid estimation of mass-transformation rates.

Site characterization to support permeable reactive barrier design

Careful design studies and selection of an effective technique for the installation of permeable reactive barriers (PRBs) are important contributors to the overall success of zero-valent iron PRBs. This article provides a case study summarizing the successful design and construction of a PRB installed at the former Carswell Air Force Base located in Fort Worth, Texas. Expedited site characterization using a cone penetrometer rig equipped with a mass spectrometer was employed to provide real-time characterization and lithologic data. These data proved to be invaluable for the design of the PRB and allowed for the development of an accurate preconstruction cost estimate. Field data gained from the expedited water quality and geologic characterization along with aquifer testing and a bench-scale treatability study provided a comprehensive basis for the design. The biopolymer slurry construction technique provided additional unanticipated benefits to the designed zero- valent iron treatment by promoting the development of anaerobic conditions favorable for microbial degradation of trichloroethene. Postconstruction monitoring data are discussed to illustrate the successful performance of the PRB. © 2005 Wiley Periodicals, Inc.

Using Multimedia Modeling to Expedite Site Characterization

This paper uses two case studies of U.S. Department of Energy nuclear weapons complex installations to illustrate the integration of expedited site characterization (ESC) and multimedia modeling in the remedial action decision making process. CONCEPTUAL SITE MODELS, MULTIMEDIA MODELS, AND EXPEDITED SITE CHARACTERIZATION: Conceptual site models outline assumptions about contaminates and the spatial/temporal distribution of potential receptors. Multimedia models simulate contaminant transport and fate through multiple environmental media, estimate potential human exposure via specific exposure pathways, and estimate the risk of cancer and non-cancer health outcomes. ESC relies on using monitoring data to quantify the key components of an initial conceptual site model that is modified iteratively using the multimedia model. Two case studies are presented that used the ESC approach: Los Alamos National Laboratory (LANL) and Pantex. LANL released radionuclides, metals, and organic compounds, into canyons surrounding the facility. The Pantex Plant has past waste management operations which included burning chemical wastes in unlined pits, burying wastes in unlined landfills, and discharging plant wastewaters into on-site surface waters. The case studies indicate that using multimedia models with the ESC approach can inform assessors about what, where, and how much site characterization data needs to be collected to reduce the uncertainty associated with risk assessment. Lowering the degree of uncertainty reduces the time and cost associated with assessing potential risk and increases the confidence that decision makers have in the assessments performed.

Innovative characterization, monitoring and sensor technologies for environmental radioactivity at USDOE sites

The mission of the U. S. Department of Energy Office of EnvironmentalManagement (EM) is to clean up its contaminated sites from the past productionof nuclear weapons. Within EM, the Office of Science and Technology (OST)is responsible for providing a full range of science and technology resourcesneeded to support resolution of EM cleanup and long-term environmental stewardshipproblems. This responsibility includes implementation of a technology developmentpathway from basic research to development, demonstration, and deploymentof scientific and technological solutions needed by DOE sites. One OST Programis the Characterization, Monitoring, and Sensor Technology Crosscutting Program(CMST-CP), which aims to provide innovative technologies (i.e., faster, better,cheaper, and/or safer) for environmental characterization and monitoring.This paper describes several technologies that CMST-CP has supported for developmentwith significant benefits realized or projected over the baseline characterizationand monitoring practices. Examples of these technologies include mapping ofsubsurface radioactivity using Cone Penetrometer and drilling techniques;a Rapid Liquid Sampler for Sr, Ra, Tc, and Cs using 3M Empore™ Rad Disks;Long-Range Alpha Detectors; a Compact High Resolution Spectrometer; BetaScint™for determination of Sr in soil; Laser-Induced Fluorescence Imaging techniquesfor mapping U on surfaces; the Environmental Measurements While Drilling System;and the Expedited Site Characterization methodology.

Role of Geophysics in Expedited Site Characterization: Case History

Expedited site characterization (ESC) is an environmental investigation approach that focuses on using nonintrusive and minimally intrusive investigative techniques synergistically to efficiently and thoroughly characterize hazardous waste sites. Unlike traditional approaches, ESC uses a dynamic (i.e., flexible) work plan with an on-site decision making team of senior-level technical staff. Another key feature of the ESC process is the emphasis on understanding site geology and hydrogeology at a high level of detail before searching for the contaminants. Geophysical techniques were successfully incorporated into an ESC project at an oil seepage basin site on the U.S. Department of Energy’s Savannah River site to define the limits of buried wastes, to detect and map an inorganic plume emanating from the waste trenches, and to define the approximate depth and lateral continuity of major stratigraphic units across the site. The geophysical techniques, integrated with minimally intrusive direct push technologies, provided the framework for the development of the conceptual site model. The refined conceptual site model was then successfully used to guide ground water contaminant sampling to define the spatial extent of the inorganic and organic plume emanating from the waste trenches.

Surface horizontal logging for radon at a Superfund site

The Department of Energy sponsored an Expedited Site Characterization study performed by Ames Laboratory at the St. Louis (Missouri) Airport Site during August-September, 1994. Uranium processing occurred there during the Cold War and significant residual radioactive contamination now exists on site. This paper reports on continuous gamma ray spectroscopy measurements to identify the emitting isotopes and to quantify the amount of radioactivity present for each. An oilfield wireline gamma ray spectrometry-sonde (the Compensated Spectral Natural Gamma instrument) was adapted to perform horizontal measurements with the detector section 3 ft above the soil surface. The results of the gamma ray spectroscopy measurements will be discussed.