bluuebunny/crossref_metadata_2025_split huggingface dataset:
Compatibility of NAPLs and Other Organic Compounds with Materials Used in Well Construction, Sampling, and Remediation
Authors: McCaulou Douglas R. , Jewett David G. , Huling Scott G. 
Published: February 2007

AbstractStructural integrity of well construction, sampling, and remediation materials may be compromised at many hazardous sites by nonaqueous phase liquids (NAPLs) and their dissolved constituents. A literature review of compatibility theory and qualitative field experiences are provided regarding the degradation and corrosion of materials in contact with NAPLs and organic compounds. A chemical compatibility table, compiled from several sources of compatibility testing results, is presented for 73 chemicals and 28 commonly used materials. Field experiences illustrate the compatibility problems of some of the common wastes and materials found at hazardous waste sites.
Synergistic Application of Four Remedial Techniques at an Industrial Site
Authors: Dasch Jean. M. , Abdul Abdul S. , Rai Devi N. , Gibson Thomas L. , Grosvenor Noel 
Published: February 2007

AbstractThe soil and ground water at a General Motors plant site were contaminated with petroleum products from leaking underground storage tanks. Based on the initial assessment, the site was complex from the standpoint of geology (clay layers), hydrology (a recharge zone with a perched water table), and contaminant (approximately 4800 gallons of mixed gasoline and oil). After a thorough study of remedial alternatives, a synergistic remedial approach was adopted including pump and treat, product removal, vapor extraction, and bioventing. The system was designed and implemented at the site through 22 dual‐extraction wells. Over a 21‐month period, 4400 gallons of gasoline and oil were removed from the system, including 59 percent by vapor extraction, 28 percent by bioventing, and 13 percent by pump and treat. Synergism between the various remedial methods was demonstrated clearly. Ground water pump and treat lowered the water table, allowing air to flow for vapor extraction. The vacuum applied for vapor extraction increased the ground water removal rate and the efficiency of pump and treat. The vapor extraction system also added oxygen to the soil to stimulate aerobic biodegradation.
Evaluation of Batch Leaching Procedures for Estimating Metal Mobility in Glaciated Soils
Authors: Lackovic Jeffrey A. , Nikolaidis Nikolaos P. , Chheda Pradeep , Carley Robert J. , Patton Elsie 
Published: February 2007

AbstractBatch leaching methods have been used for several decades to estimate the potential release of contaminants from soils. Four batch leaching procedures (toxicity characteristic leaching procedure, synthetic precitation leaching procedure, deionized water leaching procedure, and California waste extraction test) were evaluated for their ability to realistically quantify the mobility of metals from previously contaminated glaciated soils. The study was conducted using soils from four different sites (three in Connecticut and one in Maine). The results of the batch leaching procedures were compared with a set of continuous column leaching experiments performed at two different flowrates and two influent pH values. The results suggested that the synthetic precipitation leaching procedure (SPLP) was more realistic than the toxicity characteristic leaching procedure (TCLP), but still a conservative leaching estimate for evaluating the potential for metal mobility in glaciated soils. This study suggests that using SPLP as a test for estimating metal cleanup levels will result in lower remediation costs relative to TCLP or waste extraction test (WET), but still maintain a high level of confidence in the protection of ground water quality.
Effect of Rigid PVC Bailer Contact on Detection of Pesticides in Water Samples
Authors: Schuh W.M. , Cline R.L. , Kosse M.J. , Sletton D.W. 
Published: February 2007

AbstractA field experiment was conducted to examine the effect of short‐term (one minute) contact of pesticide‐laden water with a polyvinyl chloride (PVC) bailer on quantitative laboratory measurements of seven pesticide concentrations in distilled water samples subsequently decanted from the bailer. Pesticides were tested at two initial concentrations (low. based on current FPA maximum contaminant levels, or MCL: and high, based on a multiple of approximately lour times the MCL). Pesticide species included bromoxynil, diclofop‐m, dimethoate. MCPA, methyl parathion, propiconazole, and trifluralin. Dimethoate recoveries were poor for all treatments. For all other pesticides there was no systematic difference between pesticide concentrations measured before and after bailer contact. Effectiveness of bailer decontamination treatments consisting of distilled water rinse alone was related to water solubility (S) for each species. Distilled water samples decanted from a rigid PVC bailer following initial bailer contact with pesticide‐spiked water, and after the bailer had been cleaned with a single distilled water rinse, had measured pesticide concentrations of less than 2 percent of the pesticide concentration in the initial pesticide‐spiked water, regardless of S. A single distilled water rinse effectively removed all trace of contaminants having S> 500 mg/L. Multiple distilled water rinses, and multiple distilled water rinses followed by 15 bailings of a well, effectively removed all trace of contaminants having S> 50 mg/L. Below threshold S, cleaning effectiveness decreased as a power function of S.
Comparison of Fiberglass and Other Polymeric Well Casings, Part I: Susceptibility to Degradation by Chemicals
Authors: Ranney Thomas A. , Parker Louise V. 
Published: February 2007

AbstractPrevious research has shown that the most commonly used well casing materials‐stainless steel. polyvinyl chloride (PVC). and polytetra‐fluoroethylene (PTFE)‐are not suited for all monitoring environments and applications. This study is part of a series of experiments that were conducted to determine the suitability of four other polymeric well casing materials‐acrylonitrile butadiene styrene (ABS), fluorinalcd ethylene propylene (FHP), fiberglass‐reinlorced epoxy (FRE), and fiberglass‐reinforced plastic (FRP)‐ for use in ground water monitoring wells. In these studies, these four materials were compared with two other commonly used polymeric well casings, PVC and PTFE. Part I of these studies examines the resistance of these materials to degradation by chemicals. Future reports will consider sorption and leaching of organic and metal contaminants.In this study, the six materials were exposed to 28 neat organic compounds (including one acid) and to extremely acidic and alkaline aqueous solutions for up to 112 days. This was done to simulate the most aggressive environments to which monitoring well casings may be exposed. The casings were observed for changes in weight and signs of physical degradation (swelling, softening, deterioration, or dissolution).The two fluorinated polymers (FEP and PTFE) were not degraded by any of the lest chemicals. Among the nonfluorinated products tested. FRE was the most inert. Three organic chemicals caused the glass fibers to separate. and two organic solvents caused weight gains exceeding 10 percent. ABS was the most readily degraded material tested. By the end of the study, only the acid and alkaline solutions had little effect on ABS. FRP was more severely degraded by the organic chemicals than FRH but was less affected than PVC. FRP and FRE. lost weight when exposed to the highly acidic conditions.
In‐Line Measurement of Trichloroethylene Vapors Using Tin Dioxide Sensors
Authors: Heron G. , van Zutphen M. , Enfield C. G. 
Published: February 2007

AbstractDuring thermally enhanced in situ remediation of soils and ground water, gas streams are generated with varying temperatures, moisture content, and organic compound concentrations. In this study, we evaluated the performance of tin dioxide sensors for measuring trichloroethylene (TCE) concentrations in gas streams from a thermally enhanced soil vapor extraction system. Temperature, pressure, moisture content, and vapor flow rates affected the resistivity of the sensors, and thus the signal. When fluctuations in these parameters were eliminated by condensing excess water and healing to a constant temperature prior to measurement, the sensors provided reliable in‐line measurement of TCE concentrations. Gas tracers such as methane were easily monitored in‐line, providing quick and inexpensive data on subsurface vapor flow velocities and direction.
Bioavailability of Hydrophobic Organic Contaminants: Effects and Implications of Sorption‐Related Mass Transfer on Bioremediation
Authors: Zhang Wei‐xian , Bouwer Edward J. , Ball William P. 
Published: February 2007

AbstractThe low bioavailability of hydrophobic organic compounds (HOCs) is one of the key sources of uncertainty in the implementation of in situ bioremediation. Bioavailability of HOCs in the subsurface is affected by sorption/desorption processes in two important ways. First, sorption causes high organic concentrations in microporous regions and impermeable zones to which bacterial access is obstructed. Second, because desorption and immobile zone diffusion must occur before biodegradation can proceed, the overall rate of bioremediation can be limited or even controlled by these mass transfer processes, not by the activity of the degrading microorganisms. Rate models that couple sorption/desorption—related mass transfer processes and biodegradation have been successfully applied to laboratory results and are beginning to offer some insight into the problem. Specifically, the influence of sorption on biodegradation is quantified here by defining a bioavailability factor, Bf. However, many questions remain and predictive modeling is elusive, especially in the context of complicated heterogeneous natural systems. Challenges facing environmental engineers are to develop a better understanding of these processes at both laboratory and field scales and ultimately to use such understanding toward the development of more effective and economical remediation technologies.
Sampling Trace‐Level Organic Solutes with Polymeric Tubing Part 2. Dynamic Studies
Authors: Parker Louise V. , Ranney Thomas A. 
Published: February 2007

AbstractThis is the second part of a study conducted to determine whether polymeric sampling tubing can affect organic analyte concentrations during a sampling event. In this part of the study, we looked for sorption and desorption of tricholoroethylene (TCE) and leaching of organic constituents in water pumped through five types of polymeric tubing. The materials tested were a rigid fluoropolymer, a flexible fluoropolymer, low‐density polyethylene (LDPE), and two plasticized polypropylene tubings. The effects of tubing length and flow rate were examined.The least sorptive tubings, both initially and at equilibrium, were the fluoropolymers. However, in some instances the LDPE tubing had little effect on TCE concentrations. This was when a slow flow rate was used to sample relatively shallow wells (50 feet [15 m] or less) or when a faster flow rate (1 L/min) was used to sample wells that are less than 500 feet (152 m). Further testing is recommended using more sorptive analytes.Using high performance liquid chromatography (HPLC), we were unable to detect any constituents leaching from any of the tubings used in these studies, even when a slow flow rate was used. However, desorption of sorbed analytes is a concern for all the tubings tested, including the rigid fluoropolymer.
Configuring Detection Wells Near Landfills
Authors: Hudak Paul F. 
Published: February 2007

AbstractA graphical method was devised for designing contaminant detection monitoring networks in aquifers. The approach eliminates bias in detection efficiency among well pairs, thereby improving the overall efficiency of a ground water monitoring network. In the equidistant configurations derived by the graphical approach, all wells are located the same distance from a landfill, but the distance is measured parallel to ground water flow, Measured perpendicular to ground water flow, there is also an equal spacing between wells in an equidistant network. A simulation model was used to compare an equidistant network to a peripheral monitoring configuration, in which wells were spaced evenly along the downgradient boundaries of a landfill. The equidistant network yielded a 12.4% higher detection efficiency and also facilitated earlier release detection. In practice, the graphical approach that yields equidistant configurations can be used to identify candidate monitoring networks to detect potential releases from landfills.
A New Analytical Treatment of Airflow to Inlet Wells in Soil Vapor Extraction Systems
Authors: Ge Shemin 
Published: February 2007

AbstractThis paper provides a new analytical model of airflow to inlet wells in soil vapor extraction systems. It is based on a recent analytical solution of airflow to a single vapor extraction well by Bahr and Joss (1995), which updated the previous model of Baehr and Hult (1991). Baehr and Joss (1995) treated the air leakage through the surface as an air flux boundary condition, whereas Baehr and Hult (1991) approximated the leakage as a distributed source imposed in the governing airflow equation. The new analytical model shows significant improvement on air‐flow assessment over the previous model by Ge and Liao (1996), which could underestimate the efficiency of airflow to inlet wells by as much as 27% in a typical vapor extraction system.
Case History of a Large‐Scale Air Sparging/Soil Vapor Extraction System for Remediation of Chlorinated Volatile Organic Compounds in Ground Water
Authors: Gordon Matthew J. 
Published: February 2007

AbstractA large‐scale air sparging/soil vapor extraction (AS/SVE) project constructed within coastal plain sediments in New Jersey has demonstrated substantial progress toward remediating ground water through removal of volatile organic compounds (VOCs). Potential concerns identified prior to project implementation regarding hydraulic mounding, reduction in hydraulic conductivity, development of air channels, and the absence of hydraulic containment were assessed and addressed through testing and operational features incorporated into the project. At the project site, AS/SVE has successfully reduced the presence of many VOCs to undetectable levels, while reducing the concentrations of the remaining VOCs by factors of two to 500. The physical agitation caused by air sparging, and incomplete transformation from sorbed and nonaqueous phases to the vapor phase, appears to temporarily increase VOC concentrations and/or mobility of dense nonaqueous phase liquids (DN APLs) within source areas at the project site, but this is addressed in terms of subsequent removal of VOCs by properly placed downgradient treatment lines and VOCs by properly placed downgradient treatment lines and DNAPL recovery wells. This case study identifies and evaluates project‐specific features and provides empirical data for potential comparison to other candidates AS/SVE sites.
RBCA Closure at DNAPL Sites
Authors: Sheahan Joseph W. , Ball Roy O. , Hahn Melinda W. 
Published: February 2007

AbstractThe closure of sites with identified or suspected DNAPL (dense nonaqueous phase liquids) under the requirements of the Resources Conservation and Recovery Act of 1976 (RCRA), or the Comprehensive Environmental Response, Compensation and Liability Act of 1980 (CERCLA) has not been well defined. With respect to RCRA, the U.S. Environmental Protection Agency (EPA) has required that all contamination must be removed at closure such that no residual risk to human health or the environment remains. Therefore, even though many states administering the RCRA program have adopted or are considering Risk‐Based Corrective Action (RBCA) procedures (including the statistical methods described in SW‐846) for RCRA closure, the treatment of DNAPL is, at best, challenging.The methodology for closure in CERCLA is described in “Risk Assessment Guidelines for Super‐fund (RAGS),” which requires that risks above the National Contingency Plan criteria must be remediated, preferably by on‐site or in situ destruction. Most risk‐based Brownfield or voluntary cleanup programs do not provide any explicit allowance for DNAPL. However, while the ASTM methodology for RBCA in E1739‐95 (ASTM 1995) does not explicitly treat the problem of DNAPL, a basic framework for DNAPL assessment is implicitly provided.A uniform methodology for RBCA closure of VOC (volatile organic compounds) DNAPL sites can be used to achieve the program objectives of RCRA, CERCLA, and Brownfield or voluntary cleanup programs. The regulatory acceptance of the application of RBCA methods to DNAPL sites will require education and discussion, but the use of a uniform methodology should facilitate acceptance.
Laboratory Study of Polymer Solutions Used for Mobility Control During In Situ NAPL Recovery
Authors: Martel K. E. , Martel R. , Lefebvre R. , Gélinas P. J. 
Published: February 2007

AbstractThe use of surfactant solutions for the in situ recovery of residual NAPL in aquifers is increasingly considered as a viable remediation technique. The injection of a few pore volumes of high concentration surfactant solutions can mobilize most of the residual NAPL contacted by the solutions. However, the washing solutions’physico‐chemical properties (low density and high viscosity), combined with the natural porous media heterogeneity, can prevent a good sweep of the entire contaminated volume. From the petroleum industry, it is well‐known that polymer solutions can be injected following a surfactant solution slug to act as a mobility buffer and increase the overall sweep efficiency. The objective of our laboratory study is first to select and characterize polymers that would be suitable for aquifer restoration. Our experiments showed that among several polymers, xanthan gum solution rheology was made in order to predict shear rates, xanthan gum concentrations, salinity, and temperature effects on solution viscosity. The second set of experiments were made with a sand box which was designed to reproduce a simple heterogeneous media consisting of layers of sand with different permeability. These tests illustrate the xanthan gum solution's ability to increase surfactant solution's sweep efficiency and limit viscous fingering. The tests established that: (1) the injection of xanthan solution behind a surfactant solution slug decreases fluid velocity in high permeability layers and increases it in low‐permeability ones, thus increasing the sweep efficiency (2) xanthan solutions eliminate viscous fingering at the polymer/surfactant solution front; (3) a xanthan solution preflush is desirable to limit surfactant solution mobility and prevent surfactant adsorption on solids; and (4) depending on site heterogeneity injection strategies should be applied to limit overriding by low‐density surfactant solution.
Comparison of Fiberglass and Other Polymeric Well Casings, Part III. Sorption and Leaching of Trace‐Level Metals
Authors: Ranney Thomas A. , Parker Louise V. 
Published: February 2007

AbstractThis series of experiments was initiated to determine the overall suitability of three alternative polymeric well casing materials (fluorinated ethylene propylene [FEP], fiberglass‐reinforced epoxy [FRE], and fiberglass‐reinforced plastic [FRP]) for use in ground water monitoring wells and to compare these materials with polyvinyl chloride (PVC) and polytetrafluoroethylene (PTFE) well casings. This paper focuses on sorption and leaching of metals.Generally, the fiberglass materials leached more metal contaminants than PVC, FEP, and PTFE. However, with one exception (Pb leaching from FRP), leached concentrations were below maximum allowable limits set by the U.S. Environmental Protection Agency (EPA) for drinking water. With respect to sorption, none of the polymers sorbed the anions tested, but all of them sorbed one or more of the cations tested. FEP and PTFE were much less sorptive than the other materials.
A Field and Laboratory Investigation of Air Fingering During Air Sparging
Authors: Clayton Wilson S. 
Published: February 2007

AbstractSince the rejection of the bubble flow conceptual model for in situ air sparging, most practitioners have adopted the conceptual model of air channeling, which generally implies the development of widely spaced, discreet air channels that bypass large regions of the subsurface. While air channeling clearly develops in response to stratigraphic heterogeneity, the universality of widely spaced air channels in homogeneous media is not supported by available evidence. Air channeling results in low bulk air saturation due to bypassing, and field and laboratory measurements of air saturations and previously published studies were used to evaluate if air channeling is realistic. The results indicated that homogeneous coarse sands are prone to the development of air channeling, and that homogeneous fine sands show higher air saturations and are not prone to air channeling. Breakthrough air saturations, which represent the minimum air saturations, that will conduct air flow, of approximately 0.02 to 0.04 were observed in coarse sands. In contrast, breakthrough air saturations of 0.10 to 0.13 were observed in fine sands and medium sands. The transition between these behaviors falls at about 15 to 20 cm water air entry pressure. These result indicate that, at both the field and laboratory scale, coarse sands are more prone to air channeling and bypassing than fine sands. Additionally, the larger air gradients and capillary pressures in fine sands result in a less buoyancy‐dominated flow pattern, with a larger lateral extent of air flow.
A Rapid Drawdown Event Related to Quarry Operations in a Dolomite Aquifer
Authors: Onsen John J , Fassbender Wayne P. , Jurcek Patrick , Barreto Laura L. , Boyer Larry F. 
Published: February 2007

AbstractTwo active quarries are mining stone from the Silurian dolomite aquifer in Waukesha County in southeastern Wisconsin. The village in which the quarries are located uses local zoning to control the depth of mining and to institute a long‐term water level monitoring program and well guarantee/one with the quarry owners. Water levels dropped as much as 40 feet in at least 24 residential wells surrounding the quarries over a period of a few hours to days. The rapid decline in head was caused by a single boring drilled lo a depth of 75 feel he low the floor of one quarry. The borehole penetrated a localized fracture zone under confined artesian head. Water levels recovered to previous static levels within nine days after grouting the borehole. The rapid drawdown event demonstrates the potential impact of mining in fractured aquifers. The apparent complete recovery of the aquifer demonstrates that quick response can sometimes restore an aquifer. However, the potential for blasting into a similar zone illustrates the need for a well‐thought‐out aquifer monitoring program and emergency response plan. The experience of the village is a good example of managing conflicting uses of a finite resource and collecting baseline data needed to make informed decisions.