@article{borden_cha_liu_2021, title={A Physically Based Approach for Estimating Hydraulic Conductivity fromHPTPressure and Flowrate}, volume={59}, ISSN={["1745-6584"]}, DOI={10.1111/gwat.13039}, abstractNote={Abstract}, number={2}, journal={GROUNDWATER}, author={Borden, Robert C. and Cha, Ki Young and Liu, Gaisheng}, year={2021}, month={Mar}, pages={266–272} }
 @article{borden_cha_2021, title={Evaluating the impact of back diffusion on groundwater cleanup time}, volume={243}, ISSN={["1873-6009"]}, DOI={10.1016/j.jconhyd.2021.103889}, abstractNote={Back diffusion of groundwater contaminants from low permeability (K) zones can be a major factor controlling the time to reach cleanup goals in downgradient monitor wells. We identify the aquifer and contaminant characteristics that have the greatest influence on the time (TOoM) after complete source removal for contaminant concentrations to decline by 1, 2 and 3 Orders-of-Magnitude (T1, T2 and T3). Two aquifer configurations are evaluated: (a) layered geometry (LG) with finite thickness low K layers; and (b) boundary geometry (BG) with thick semi-infinite low K boundaries. A semi-analytical modeling approach (Muskus and Falta, 2018) is used to simulate the concentration decline following source removal for a range of conditions and generate ≈21,000 independent values of T1, T2 and T3. Linear regression is applied to interpret this large dataset and develop simple relationships to estimate TOoM from three characteristic parameters - the mass residence time (TM), diffusion time (TD), and ratio of low K to high K mass storage (γ). TM is most important predictor of T1, T2 and T3 for both geometries and is equal to the combined high and low K contaminant mass divided by the mass flux, at the end of the loading period (TL). For LG, T3 is strongly influenced by TD = RLLD2/(4D*), where RL is the low K retardation factor, LD is the half-thickness of the embedded low K layers, and D* is the effective diffusion coefficient. For BG, T3 is strongly influenced by γ. Contaminant decay in low K zones can significantly reduce cleanup times when λLTD > 0.01, where λL is the effective first order decay rate in the low K zone. The 1st Damköhler (Da), equal to TM/TD, provides a useful indicator of the relative importance of back diffusion on TOoM. Back diffusion impacts are greatest on T3 when 0.01 > Da > 0.1, then decrease with increasing Da. Back diffusion has less impacts on T2, with limited influence on T1. The results are summarized in a simple conceptual model to aid in evaluating the impact of back diffusion on the time for concentrations to decline by 1-3 OoM.}, journal={JOURNAL OF CONTAMINANT HYDROLOGY}, author={Borden, Robert C. and Cha, Ki Young}, year={2021}, month={Dec} }
 @article{kim_parker_borden_2019, title={Stochastic cost-optimization and risk assessment of in situ chemical oxidation for dense non-aqueous phase liquid (DNAPL) source remediation}, volume={33}, ISSN={["1436-3259"]}, DOI={10.1007/s00477-018-1633-y}, abstractNote={This study involved development of a computer program to determine optimal design variables for in situ chemical oxidation (ISCO) of dense nonaqueous phase liquid (DNAPL) sites to meet site-wide remediation objectives with minimum life-cycle remediation cost while taking uncertainty in site characterization data and model predictions into consideration. A physically-based ISCO performance model computes field-scale DNAPL dissolution, instantaneous reaction of oxidant with contaminant and with readily oxidizable natural oxidant demand (NOD), second-order kinetic reactions for slowly oxidizable NOD, and time to reach ISCO termination criteria. Remediation cost is computed by coupling the performance model with a cost module. ISCO termination protocols are implemented that allow different treatment subregions (e.g., zones with different estimated contaminant concentrations) to be terminated independently based on statistical criteria related to confidence limits of contaminant concentrations estimated from soil and/or groundwater sampling data. The ISCO model was implemented in the program called Stochastic Cost Optimization Toolkit, which includes modules for additional remediation technologies that can be implemented serially or in parallel coupled with a dissolved plume model to enable design optimization to meet plume-scale cleanup objectives. This study focuses on optimization of ISCO design to meet specified source zone remediation objectives. ISCO design parameters considered for optimization include oxidant concentration and injection rate, frequency and number of soil or groundwater samples, and cleanup criteria for termination of subregion injection. Sensitivity studies and example applications are presented to demonstrate the benefits of proposed stochastic optimization methodology.}, number={1}, journal={STOCHASTIC ENVIRONMENTAL RESEARCH AND RISK ASSESSMENT}, author={Kim, Ungtae and Parker, Jack C. and Borden, Robert C.}, year={2019}, month={Jan}, pages={73–89} }
 @article{won_borden_2017, title={Laboratory column evaluation of high explosives attenuation in grenade range soils}, volume={46}, number={5}, journal={Journal of Environmental Quality}, author={Won, J. and Borden, R. C.}, year={2017}, pages={968–974} }
 @article{borden_won_yuncu_2017, title={Natural and enhanced attenuation of explosives on a hand grenade range}, volume={46}, number={5}, journal={Journal of Environmental Quality}, author={Borden, R. C. and Won, J. and Yuncu, B.}, year={2017}, pages={961–967} }
 @article{won_borden_2016, title={Impact of glycerin and lignosulfonate on biodegradation of high explosives in soil}, volume={194}, ISSN={["1873-6009"]}, DOI={10.1016/j.jconhyd.2016.08.008}, abstractNote={Soil microcosms were constructed and monitored to evaluate the impact of substrate addition and transient aerobic and anaerobic conditions on TNT, RDX and HMX biodegradation in grenade range soils. While TNT was rapidly biodegraded under both aerobic and anaerobic conditions with and without organic substrate, substantial biodegradation of RDX, HMX, and RDX daughter products was not observed under aerobic conditions. However, RDX and HMX were significantly biodegraded under anaerobic conditions, without accumulation of TNT or RDX daughter products (2-ADNT, 4-ADNT, MNX, DNX, and TNX). In separate microcosms containing grenade range soil, glycerin and lignosulfonate addition enhanced oxygen consumption, increasing the consumption rate >200% compared to untreated soils. Mathematical model simulations indicate that oxygen consumption rates of 5 to 20g/m3/d can be achieved with reasonable amendment loading rates. These results indicate that glycerin and lignosulfonate can be potentially used to stimulate RDX and HMX biodegradation by increasing oxygen consumption rates in soil.}, journal={JOURNAL OF CONTAMINANT HYDROLOGY}, author={Won, Jongho and Borden, Robert C.}, year={2016}, month={Nov}, pages={1–9} }
 @article{tillotson_borden_2015, title={Statistical Analysis of Secondary Water Quality Impacts from Enhanced Reductive Bioremediation}, volume={35}, ISSN={["1745-6592"]}, DOI={10.1111/gwmr.12132}, abstractNote={Abstract}, number={4}, journal={GROUND WATER MONITORING AND REMEDIATION}, author={Tillotson, J. M. and Borden, R. C.}, year={2015}, pages={67–77} }
 @article{hiortdahl_borden_2014, title={Enhanced Reductive Dechlorination of Tetrachloroethene Dense Nonaqueous Phase Liquid with EVO and Mg(OH)(2)}, volume={48}, ISSN={["1520-5851"]}, DOI={10.1021/es4042379}, abstractNote={In situ treatment of dense nonaqueous phase liquids (DNAPL) by enhanced reductive dechlorination (ERD) can be limited by contaminant toxicity, low pH, and challenges in effectively delivering electron donor. Flushing emulsified vegetable oil (EVO), colloidal Mg(OH)2 buffer, and a bioaugmentation culture (BC) through a zone containing neat tetrachloroethene (PCE) was effective in reducing contaminant toxicity, limiting pH declines, and accelerating bioenhanced dissolution of the DNAPL. In the effluent of porous media columns with little fine material, PCE concentrations reached a maximum of 40-50 times PCE aqueous solubility in water, demonstrating NAPL PCE was distributed throughout the 1.5 m column length. In a column treated with only EVO+BC, reductive dechlorination was limited. However, a single injection of EVO+Mg(OH)2+BC was effective in reducing PCE to below detection for over 400 days with a large increase in Cl(-) and dichloroethene (DCE), accelerating bioenhanced DNAPL dissolution. Dechlorination rates gradually increased over time with the rate of total ethene (TE) release from the Mg(OH)2+EVO+BC column reaching 5-6 times the TE release rate from the EVO+BC column. The accelerated dechlorination was likely due to both Mg(OH)2 addition which limited pH declines from HCl, volatile fatty acids (VFAs), and inorganic carbon (IC) production, and formation of a mixed PCE-vegetable oil NAPL which provided a readily accessible electron donor, resulting in rapid PCE degradation with reduced PCE toxicity.}, number={1}, journal={ENVIRONMENTAL SCIENCE & TECHNOLOGY}, author={Hiortdahl, Kirsten M. and Borden, Robert C.}, year={2014}, month={Jan}, pages={624–631} }
 @article{borden_knox_lieberman_ogles_2014, title={Perchlorate natural attenuation in a riparian zone}, volume={49}, ISSN={["1532-4117"]}, DOI={10.1080/10934529.2014.897145}, abstractNote={Multiple lines of evidence were used to document the natural attenuation of perchlorate in a shallow alluvial aquifer. In the upgradient, aerobic portion of the aquifer, perchlorate did not biodegrade. However, natural flushing by groundwater flow is reducing perchlorate concentrations in the aquifer over time. Perchlorate concentrations in the source area are expected to meet cleanup criteria in 11 to 27 years without active remedial measures. At the distal end of the plume, perchlorate is rapidly degraded as it migrates upward through organic rich littoral zone sediments. Apparent first-order degradation rates in groundwater were about 0.20 d−1 and are consistent with laboratory macrocosm rates (0.12 d−1). qPCR results show a distinct region of the littoral zone where perchlorate degraders are elevated. The Eh within this zone varies from +0.1 to +0.3 V indicating perchlorate degraders can thrive in moderately oxidizing conditions. The study has shown that (i) there was no apparent perchlorate biodegradation in aerobic aquifer; (ii) perchlorate declines over time in aerobic aquifer due to flushing; (iii) there was a rapid perchlorate attenuation in organic rich littoral zone; and, (iv) qPCR results show large increases in perchlorate degraders in the littoral zone.}, number={10}, journal={JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH PART A-TOXIC/HAZARDOUS SUBSTANCES & ENVIRONMENTAL ENGINEERING}, author={Borden, Robert C. and Knox, Sheri L. and Lieberman, M. Tony and Ogles, Dora}, year={2014}, pages={1100–1109} }
 @article{rogers_reyes_beckwith_borden_2014, title={Power earth auger modification for waste extraction from pit latrines}, volume={4}, ISSN={["2043-9083"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84896480247&partnerID=MN8TOARS}, DOI={10.2166/washdev.2013.183}, abstractNote={The extraction auger was developed to meet the need for a low cost, effective method to empty pit latrines in difficult to access locations. The basic design consists of a motor that rotates an auger inside a pipe, lifting waste from a pit and depositing it into containers through a wye fitting at the top of the device. Laboratory testing of the auger showed increases in flow rates with increasing auger rotational speed and waste viscosity. An auger with an external hydraulic drive was capable of lifting dairy waste over 2.5 m, at flow rates of over 125 liters per minute. Field-testing showed the equipment was effective at lifting medium viscosity wastes containing a mixture of liquid and solid material. However, the auger was not effective in removing low viscosity, liquid waste that would flow backward down the auger reducing lifting efficiency. The auger was capable of drilling into dense solid waste, forming a ‘posthole’ in the waste. However, since the dense solid waste would not flow towards the auger intake, actual waste removal from the pit was limited. Improved methods are needed to mix liquid and solid waste in pits prior to removal with the extraction auger or other technologies.}, number={1}, journal={JOURNAL OF WATER SANITATION AND HYGIENE FOR DEVELOPMENT}, publisher={IWA Publishing}, author={Rogers, Tate Weston and Reyes, Francis L., III and Beckwith, Walter J. and Borden, Robert C.}, year={2014}, pages={72–80} }
 @article{cha_borden_2012, title={Impact of injection system design on ISCO performance with permanganate - mathematical modeling results}, volume={128}, ISSN={["1873-6009"]}, DOI={10.1016/j.jconhyd.2011.10.001}, abstractNote={In situ chemical oxidation (ISCO) using permanganate (MnO4−) can be a very effective technique for remediation of soil and groundwater contaminated with chlorinated solvents. However, many ISCO projects are less effective than desired because of poor delivery of the chemical reagents to the treatment zone. In this work, the numerical model RT3D was modified and applied to evaluate the effect of aquifer characteristics and injection system design on contact and treatment efficiency. MnO4− consumption was simulated assuming the natural oxidant demand (NOD) is composed of a fraction that reacts instantaneously and a fraction that slowly reacts following a 2nd order relationship where NOD consumption rate increases with increasing MnO4− concentration. MnO4− consumption by the contaminant was simulated as an instantaneous reaction. Simulation results indicate that the mass of permanganate and volume of water injected has the greatest impact on aquifer contact efficiency and contaminant treatment efficiency. Several small injection events are not expected to increase contact efficiency compared to a single large injection event, and can increase the amount of un-reacted MnO4− released down-gradient. High groundwater flow velocities can increase the fraction of aquifer contacted. Initial contaminant concentration and contaminant retardation factor have only a minor impact on volume contact efficiency. Aquifer heterogeneity can have both positive and negative impacts on remediation system performance, depending on the injection system design.}, number={1-4}, journal={JOURNAL OF CONTAMINANT HYDROLOGY}, author={Cha, Ki Young and Borden, Robert C.}, year={2012}, month={Feb}, pages={33–46} }
 @article{cha_crimi_urynowicz_borden_2012, title={Kinetics of Permanganate Consumption by Natural Oxidant Demand in Aquifer Solids}, volume={29}, ISSN={["1557-9018"]}, DOI={10.1089/ees.2011.0211}, abstractNote={Abstract Effectiveness of permanganate (\documentclass{aastex}\usepackage{amsbsy}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{bm}\usepackage{mathrsfs}\usepackage{pifont}\usepackage{stmaryrd}\usepackage{textcomp}\usepackage{portland, xspace}\usepackage{amsmath, amsxtra}\pagestyle{empty}\DeclareMathSizes{10}{9}{7}{6}\begin{document} $${\rm MnO}_4^-$$ \end{document}) injection for in situ chemical oxidation is often controlled by the natural oxidant demand (NOD) of the aquifer solids. In this work, a simple procedure was developed and applied to generate a database of NOD kinetic parameters for six different models for 50 different aquifer materials. Representing oxidant consumption as an initial instantaneous reaction with a portion of the total NOD and as a second order reaction between \documentclass{aastex}\usepackage{amsbsy}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{bm}\usepackage{mathrsfs}\usepackage{pifont}\usepackage{stmaryrd}\usepackage{textcomp}\usepackage{portland, xspace}\usepac...}, number={7}, journal={ENVIRONMENTAL ENGINEERING SCIENCE}, author={Cha, Ki Young and Crimi, Michelle and Urynowicz, Michael A. and Borden, Robert C.}, year={2012}, month={Jul}, pages={646–653} }
 @article{behrooz_borden_2012, title={Physical, Hydrologic, and Aqueous Chemical Characterization of the Ore Knob Tailings Pile (Ashe County, North Carolina, USA)}, volume={31}, ISSN={["1616-1068"]}, DOI={10.1007/s10230-011-0166-0}, number={1}, journal={MINE WATER AND THE ENVIRONMENT}, author={Behrooz, Mehrnoosh and Borden, Robert C.}, year={2012}, month={Mar}, pages={3–15} }
 @article{behrooz_borden_2012, title={Waste Glycerol Addition to Reduce AMD Production in Unsaturated Mine Tailings}, volume={31}, ISSN={["1616-1068"]}, DOI={10.1007/s10230-012-0180-x}, number={3}, journal={MINE WATER AND THE ENVIRONMENT}, author={Behrooz, Mehrnoosh and Borden, Robert C.}, year={2012}, month={Sep}, pages={161–171} }
 @article{valiquette_robinson_borden_2010, title={Energy Efficiency and Rod Length Effect in Standard Penetration Test Hammers}, ISSN={["2169-4052"]}, DOI={10.3141/2186-06}, abstractNote={Twenty-eight standard penetration test (SPT) hammers owned by the North Carolina Department of Transportation and private consultants were used to investigate the average energy efficiency and variability of manual versus automatic hammers, as well as the effect of SPT rod length on hammer efficiency. The results agree with published data in several regards. Automatic hammers in the study were found to have an average transferred efficiency of 80.9%. This finding agrees very well with the 80% efficiency assumed in geotechnical engineering practice for automatic hammers. Manual hammers in the study averaged 63.9%, close to the 60% efficiency assumed for manual hammers. Manual hammers were found to be twice as variable as automatic hammers in transferred energy from blow to blow within an SPT blow count. The study demonstrated that the measured transferred energy appeared to be affected by rod length. Lengths shorter than approximately 40 ft caused reduced energy to be transferred into the rod. An empirical formula is presented for correcting short rod length energy losses. The data did not demonstrate a strong dependence on SPT N-value, although the data set lacked observations where the N-value was less than 6 blows per ft.}, number={2186}, journal={TRANSPORTATION RESEARCH RECORD}, author={Valiquette, Michael and Robinson, Brent and Borden, Roy H.}, year={2010}, pages={47–56} }
 @article{hatzinger_bohlke_sturchio_gu_heraty_borden_2009, title={Fractionation of stable isotopes in perchlorate and nitrate during in situ biodegradation in a sandy aquifer}, volume={6}, ISSN={["1448-2517"]}, DOI={10.1071/EN09008}, abstractNote={Environmental context. Perchlorate (ClO4–) and nitrate (NO3–) are common co-contaminants in groundwater, with both natural and anthropogenic sources. Each of these compounds is biodegradable, so in situ enhanced bioremediation is one alternative for treating them in groundwater. Because bacteria typically fractionate isotopes during biodegradation, stable isotope analysis is increasingly used to distinguish this process from transport or mixing-related decreases in contaminant concentrations. However, for this technique to be useful in the field to monitor bioremediation progress, isotope fractionation must be quantified under relevant environmental conditions. In the present study, we quantify the apparent in situ fractionation effects for stable isotopes in ClO4– (Cl and O) and NO3– (N and O) resulting from biodegradation in an aquifer. Abstract. An in situ experiment was performed in a shallow alluvial aquifer in Maryland to quantify the fractionation of stable isotopes in perchlorate (Cl and O) and nitrate (N and O) during biodegradation. An emulsified soybean oil substrate that was previously injected into this aquifer provided the electron donor necessary for biological perchlorate reduction and denitrification. During the field experiment, groundwater extracted from an upgradient well was pumped into an injection well located within the in situ oil barrier, and then groundwater samples were withdrawn for the next 30 h. After correction for dilution (using Br– as a conservative tracer of the injectate), perchlorate concentrations decreased by 78% and nitrate concentrations decreased by 82% during the initial 8.6 h after the injection. The observed ratio of fractionation effects of O and Cl isotopes in perchlorate (ϵ18O/ϵ37Cl) was 2.6, which is similar to that observed in the laboratory using pure cultures (2.5). Denitrification by indigenous bacteria fractionated O and N isotopes in nitrate at a ratio of ~0.8 (ϵ18O/ϵ15N), which is within the range of values reported previously for denitrification. However, the magnitudes of the individual apparent in situ isotope fractionation effects for perchlorate and nitrate were appreciably smaller than those reported in homogeneous closed systems (0.2 to 0.6 times), even after adjustment for dilution. These results indicate that (1) isotope fractionation factor ratios (ϵ18O/ϵ37Cl, ϵ18O/ϵ15N) derived from homogeneous laboratory systems (e.g. pure culture studies) can be used qualitatively to confirm the occurrence of in situ biodegradation of both perchlorate and nitrate, but (2) the magnitudes of the individual apparent ϵ values cannot be used quantitatively to estimate the in situ extent of biodegradation of either anion.}, number={1}, journal={ENVIRONMENTAL CHEMISTRY}, author={Hatzinger, Paul B. and Bohlke, John Karl and Sturchio, Neil C. and Gu, Baohua and Heraty, Linnea J. and Borden, Robert C.}, year={2009}, pages={44–52} }
 @article{clayton_borden_2009, title={Numerical Modeling of Emulsified Oil Distribution in Heterogeneous Aquifers}, volume={47}, ISSN={["1745-6584"]}, DOI={10.1111/j.1745-6584.2008.00531.x}, abstractNote={Abstract}, number={2}, journal={GROUND WATER}, author={Clayton, Matthew H. and Borden, Robert C.}, year={2009}, pages={246–258} }
 @article{borden_2007, title={Concurrent bioremediation of perchlorate and 1,1,1-trichloroethane in an emulsified oil barrier}, volume={94}, ISSN={["0169-7722"]}, DOI={10.1016/j.jconhyd.2007.06.002}, abstractNote={A detailed field pilot test was conducted to evaluate the use of edible oil emulsions for enhanced in situ biodegradation of perchlorate and chlorinated solvents in groundwater. Edible oil substrate (EOS®) was injected into a line of ten direct push injection wells over a 2-day period to form a 15-m-long biologically active permeable reactive barrier (bio-barrier). Field monitoring results over a 2.5-year period indicate the oil injection generated strongly reducing conditions in the oil-treated zone with depletion of dissolved oxygen, nitrate, and sulfate, and increases in dissolved iron, manganese and methane. Perchlorate was degraded from 3100 to 20,000 μg/L to below detection (< 4 μg/L) in the injection and nearby monitor wells within 5 days following the injection. Two years after the single emulsion injection, perchlorate was less than 6 μg/L in every downgradient well compared to an average upgradient concentration of 13,100 μg/L. Immediately after emulsion injection, there were large shifts in concentrations of chlorinated solvents and degradation products due to injection of clean water, sorption to the oil and adaptation of the in situ microbial community. Approximately 4 months after emulsion injection, concentrations of 1,1,1-trichloroethane (TCA), perchloroethene (PCE), trichloroethene (TCE) and their degradation products appeared to reach a quasi steady-state condition. During the period from 4 to 18 months, TCA was reduced from 30–70 μM to 0.2–4 μM during passage through the bio-barrier. However, 1–9 μM 1,1-dichloroethane (DCA) and 8–14 μM of chloroethane (CA) remained indicating significant amounts of incompletely degraded TCA were discharging from the oil-treated zone. During this same period, PCE and TCE were reduced with concurrent production of 1,2-cis-dichloroethene (cis-DCE). However, very little VC or ethene was produced indicating reductive dechlorination slowed or stopped at cis-DCE. The incomplete removal of TCA, PCE and TCE is likely associated with the short (5–20 days) hydraulic retention time of contaminants in the oil-treated zone. The permeability of the injection wells declined by 39–91% (average = 68%) presumably due to biomass growth and/or gas production. However, non-reactive tracer tests and detailed monitoring of the perchlorate plume demonstrated that the permeability loss did not result in excessive flow bypassing around the bio-barrier. Contaminant transport and degradation within the bio-barrier was simulated using an advection–dispersion–reaction model where biodegradation rate was assumed to be linearly proportional to the residual oil concentration (Soil) and the contaminant concentration. Using this approach, the calibrated model was able to closely match the observed contaminant distribution. The calibrated model was then used to design a full-scale barrier to treat both ClO4 and chlorinated solvents.}, number={1-2}, journal={JOURNAL OF CONTAMINANT HYDROLOGY}, author={Borden, Robert C.}, year={2007}, month={Oct}, pages={13–33} }
 @article{borden_2007, title={Effective distribution of emulsified edible oil for enhanced anaerobic bioremediation}, volume={94}, DOI={10.1016/jjconhyd.2007.06.001}, number={1-2}, journal={Journal of Contaminant Hydrology}, author={Borden, R. C.}, year={2007}, pages={1–12} }
 @article{long_borden_2006, title={Enhanced reductive dechlorination in columns treated with edible oil emulsion}, volume={87}, ISSN={["1873-6009"]}, DOI={10.1016/j.jconhyd.2006.04.010}, abstractNote={The effect of edible oil emulsion treatment on enhanced reductive dechlorination was evaluated in a 14 month laboratory column study. Experimental treatments included: (1) emulsified soybean oil and dilute HCl to inhibit biological activity; (2) emulsified oil only; (3) emulsified oil and anaerobic digester sludge; and (4) continuously feeding soluble substrate. A single application of emulsified oil was effective in generating strongly reducing, anaerobic conditions for over 14 months. PCE was rapidly reduced to cis-DCE in all three live columns. Bioaugmentation with a halorespiring enrichment culture resulted in complete dechlorination of PCE to ethene in the soluble substrate column (yeast extract and lactate). However, an additional treatment with a pulse of yeast extract and bioaugmentation culture was required to stimulate complete dechlorination in the emulsion treated columns. Once the dechlorinating population was established, the emulsion only column degraded PCE from 90–120 μM to below detection with concurrent ethene production in a 33 day contact time. The lower biodegradation rates in the emulsion treated columns compared to the soluble substrate column suggest that emulsified oil barriers may require a somewhat longer contact time for effective treatment. In the HCl inhibited column, partitioning of PCE to the retained oil substantially delayed PCE breakthrough. However, reduction of PCE to more soluble degradation products (cis-DCE, VC and ethene) greatly reduced the impact of oil–water partitioning in live columns. There was only a small decline in the hydraulic conductivity (K) of column #1 (low pH + emulsion, Kfinal/Kinitial = 0.57) and column #2 (live + emulsion, Kfinal/Kinitial = 0.73) indicating emulsion injection did not result in appreciable clogging of the clayey sand. However, K loss was greater in column #3 (sludge +emulsion, Kfinal/Kinitial = 0.12) and column #4 (soluble substrate, Kfinal/Kinitial = 0.03) indicating clogging due to biomass and/or gas production can be significant.}, number={1-2}, journal={JOURNAL OF CONTAMINANT HYDROLOGY}, author={Long, Cameron M. and Borden, Robert C.}, year={2006}, month={Sep}, pages={54–72} }
 @article{jung_coulibaly_borden_2006, title={Transport of edible oil emulsions in clayey sands: 3D sandbox results and model validation}, volume={11}, DOI={10.1061/(ASCE)1084-0699(2006)11:3(238)}, abstractNote={Injection of edible oils into the subsurface can provide an effective, low-cost alternative for stimulating anaerobic bioreme- diation processes. However, concerns have been raised about the effects of oil buoyancy and variations in aquifer permeability on the final distribution of oil in the subsurface. Three-dimensional 3D sandbox experiments 1.2 m0.98 m0.98 m were conducted to study the distribution of edible oil emulsions under homogeneous and heterogeneous conditions. A fine emulsion was first injected followed by chase water to distribute the emulsion throughout the sandbox. This approach was very effective, resulting in a reasonably uniform volatile solids distribution in the top, middle, and bottom layers, measured 5 and 7 weeks after the completion of emulsion injection. A standard colloidal transport model that includes a Langmuirian blocking function was used to simulate emulsion transport and retention in the 3D sandbox. All parameters for the emulsion transport model were measured independently. Simulations results generally matched observed values for both the homogeneous and heterogeneous injection tests demonstrating that this approach can be used to describe the transport and distribution of emulsified oil in sandy sediments.}, number={3}, journal={Journal of Hydrologic Engineering}, author={Jung, Y. and Coulibaly, K. M. and Borden, R. C.}, year={2006}, pages={238–244} }
 @article{coulibaly_long_borden_2006, title={Transport of edible oil emulsions in clayey sands: One-dimensional column results and model development}, volume={11}, DOI={10.1061/(ASCE)1084-0699(2006)11:3(230)}, abstractNote={The transport and retention of a soybean oil-in-water emulsion was evaluated in laboratory columns packed with a medium to fine clayey sand amended with varying amounts of kaolinite. Results from these experiments demonstrated that appropriately prepared soybean oil-in-water emulsions can be distributed in clayey sand at least 80 cm away from injection point. Kaolinite addition to the clayey sand resulted in an increase in the maximum oil retention. However, the empty bed collision efficiencies in columns packed with clayey sand amended with kaolinite were lower than in columns packed with only clayey sand, suggesting that kaolinite is a less efficient collector of oil droplets than natural clayey sand. A standard colloidal transport model provided an adequate description of effluent breakthrough and the final oil distribution in the laboratory columns. This transport model was implemented as a user defined module within RT3D. Model parameters determined in replicate columns and at varying velocities were reasonably reproducible.}, number={3}, journal={Journal of Hydrologic Engineering}, author={Coulibaly, K. M. and Long, C. M. and Borden, R. C.}, year={2006}, pages={230–237} }
 @article{zenker_borden_barlaz_2004, title={Biodegradation of 1,4-dioxane using trickling filter}, volume={130}, DOI={10.1061/(asce)0733-9372(2004)130:9(926)}, abstractNote={The ability of a laboratory-scale trickling filter to biodegrade cyclic ethers was investigated and a simple kinetic model was developed to predict ether biodegradation. The trickling filter received a feed solution designed to mimic ether concentrations typically encountered in contaminated groundwater. The reactor was operated for approximately 1 year and was capable of biodegrading 93.97% of 1,4-dioxane at various loading rates in the obligate presence of tetrahydrofuran (THF) as the growth substrate. A simple tanks-in-series hydraulic model combined with a kinetic model that incorporated cometabolism was utilized to simulate removal of THF and 1,4-dioxane. Model simulations of THF removal were satisfactory for all loading rates analyzed. However, the model somewhat over predicted 1,4-dioxane removal. This research demonstrates the ability to treat groundwater contaminated with low concentrations of ethers in attached growth reactors.}, number={9}, journal={Journal of Environmental Engineering (New York, N.Y.)}, author={Zenker, M. J. and Borden, R. C. and Barlaz, Morton}, year={2004}, pages={926–931} }
 @article{coulibaly_borden_2004, title={Impact of edible oil injection on the permeability of aquifer sands}, volume={71}, ISSN={["0169-7722"]}, DOI={10.1016/j.jconhyd.2003.10.002}, abstractNote={Recent laboratory and field studies have shown that food-grade edible oils can be injected into the subsurface for installation of in-situ permeable reactive barriers. However to be effective, the oil must be distributed out away from the oil injection points without excessive permeability loss. In this work, we examine the distribution of soybean oil in representative aquifer sediments as non-aqueous phase liquid oil (NAPL oil) or as an oil-in-water emulsion. Laboratory columns packed with sands or clayey sands were flushed with either NAPL oil or a soybean emulsion followed by plain water, while monitoring permeability loss and the final oil residual saturation. NAPL oil can be injected into coarse-grained sands. However NAPL injection into finer grained sediments requires high injection pressures which may not be feasible at some sites. In addition, NAPL injection results in high oil residual saturations and moderate permeability losses. In contrast, properly prepared emulsions can be distributed through sands with varying clay content without excessive pressure buildup, low oil retention and very low to moderate permeability loss. For effective transport, the emulsion must be stable, the oil droplets must be significantly smaller than the mean pore size of the sediment and the oil droplets should have a low to moderate tendency to stick to each other and the aquifer sediments. In our work, oil retention and associated permeability loss increased with sediment clay content and with the ratio of droplet size to pore size. For sandy sediments, the permeability loss is modest (0–40% loss) and is proportional to the oil residual saturation.}, number={1-4}, journal={JOURNAL OF CONTAMINANT HYDROLOGY}, author={Coulibaly, KM and Borden, RC}, year={2004}, month={Jul}, pages={219–237} }
 @article{zenker_borden_barlaz_2003, title={Occurrence and treatment of 1,4-dioxane in aqueous environments}, volume={20}, ISSN={["1092-8758"]}, DOI={10.1089/109287503768335913}, abstractNote={1,4-Dioxane is classified as a probable human carcinogen. It is used as a stabilizer for chlorinated solvents, particularly, 1,1,1-trichloroethane (TCA), and it is formed as a by-product during the manufacture of polyester and various polyethoxylated compounds. Improper disposal of industrial waste and accidental solvent spills have resulted in the contamination of groundwater with 1,4-dioxane. Volatilization and sorption are not significant attenuation mechanisms due to 1,4-dioxane's complete miscibility with water. At present, advanced oxidation processes (AOPs) are the only proven technology for 1,4-dioxane treatment. 1,4-Dioxane was believed to be very resistant to both abiotic and biologically mediated degradation due to its heterocyclic structure with two ether linkages. However, recent studies have shown that 1,4-dioxane can be biodegraded as a sole carbon and energy source, and that cost-effective biological treatment processes can be developed. Future work should be oriented towards the developme...}, number={5}, journal={ENVIRONMENTAL ENGINEERING SCIENCE}, author={Zenker, MJ and Borden, RC and Barlaz, MA}, year={2003}, pages={423–432} }
 @article{borden_2002, title={Chlorinated solvent cleanup with edible oils}, volume={34}, number={10}, journal={Pollution Engineering}, author={Borden, B.}, year={2002}, pages={16–19} }
 @article{barlaz_rooker_kjeldsen_gabr_borden_2002, title={Critical evaluation of factors required to terminate the postclosure monitoring period at solid waste landfills}, volume={36}, ISSN={["1520-5851"]}, DOI={10.1021/es011245u}, abstractNote={Regulations governing the disposal of solid waste in landfills specify that they must be monitored for 30 years after closure unless this period is extended by the governing regulatory authority. Given the wide range of conditions under which refuse is buried, technical criteria, rather than a specific time period, are preferable for evaluation of when it is acceptable to terminate postclosure monitoring. The objectives of this paper are to identify and evaluate parameters that can be used to define the end of the postclosure monitoring period and to present a conceptual framework for an investigation of whether postclosure monitoring can be terminated at a landfill. Parameters evaluated include leachate composition and leachate and gas production. Estimates of leachate production from closed landfills are used to assess the potential environmental impacts of a hypothetical release to surface water or groundwater. The acceptability of gaseous releases should be evaluated against criteria for odors, the potential for subsurface migration, and greenhouse gas and ozone precursor emissions. The approach presented here must be tested on a site-specific basis to identify additional data requirements and regulatory activity that might be required to prepare regulators for the large number of requests to terminate postclosure monitoring expected over the next 20 years. An approach in which the frequency and extent of postclosure monitoring is reduced as warranted by site-specific data and impact analysis should provide an effective strategy to manage closed landfills.}, number={16}, journal={ENVIRONMENTAL SCIENCE & TECHNOLOGY}, author={Barlaz, MA and Rooker, AP and Kjeldsen, P and Gabr, MA and Borden, RC}, year={2002}, month={Aug}, pages={3457–3464} }
 @article{borden_black_mcblief_2002, title={MTBE and aromatic hydrocarbons in North Carolina stormwater runoff}, volume={118}, ISSN={["1873-6424"]}, DOI={10.1016/S0269-7491(01)00204-4}, abstractNote={A total of 249 stormwater samples were collected from 46 different sampling locations in North Carolina over an approximate 1-year period and analyzed to identify land use types where fuel oxygenates and aromatic hydrocarbons may be present in higher concentrations and at greater frequency. Samples were analyzed by gas chromatography-mass spectrometry in ion selective mode to achieve a quantitation limit of 0.05 microg/l. m-,p-Xylene and toluene were detected in over half of all samples analyzed, followed by MTBE: o-xylene: 1,3,5-trimethylbenzene: ethylbenzene; and 1,2,4-trimethylbenzene. Benzene, DIPE, TAME and 1,2,3-trimethylbenzene were detected in < 10% of the samples analyzed. Median contaminant concentrations (when detected) varied from 0.07 microg/l for ethylbenzene to 0.11 microg/l for toluene. All of the locations with significantly higher contaminant concentrations were associated with direct runoff from a gas station or discharge of contaminated groundwater from a former leaking underground storage tank. For all of the aromatic hydrocarbons, the maximum observed contaminant concentrations were over an order of magnitude lower than current drinking water standards.}, number={1}, journal={ENVIRONMENTAL POLLUTION}, author={Borden, RC and Black, DC and McBlief, KV}, year={2002}, pages={141–152} }
 @article{zenker_borden_barlaz_2002, title={Modeling cometabolism of cyclic ethers}, volume={19}, ISSN={["1092-8758"]}, DOI={10.1089/109287502760271535}, abstractNote={The biodegradation kinetics of a mixed culture with the ability to cometabolically degrade 1,4-dioxane in the presence of tetrahydrofuran (THF) were studied using a previously published model. Base...}, number={4}, journal={ENVIRONMENTAL ENGINEERING SCIENCE}, author={Zenker, MJ and Borden, RC and Barlaz, MA}, year={2002}, pages={215–228} }
 @article{kao_kota_ress_barlaz_borden_2001, title={Effects of subsurface heterogeneity on natural bioremediation at a gasoline spill site}, volume={43}, ISSN={["0273-1223"]}, DOI={10.2166/wst.2001.0322}, abstractNote={A test cell of 3-m by 6-m located at the mid-point of a gasoline spill site was selected to test the hypothesis that the rate of hydrocarbon biodegradation is influenced by the spatial distribution of the electron acceptors, aqueous geochemistry, and microbial population. Multilevel samplers (MLSs) were installed at four corners of the test cell for groundwater sampling. Sampling ports were placed at 0.3-m intervals from 1.5 to 4.8 m below land surface (bls). A 0.91-m by 12.7-cm sediment core (from 3.3 to 4.2 m bls) in the center of the MLSs was collected. The core was cut into 7 sections, and each was used for sediment extractions, microbial enumeration, grain size distribution, and microcosm studies. Groundwater analytical results indicate that iron reduction was the dominant biodegradation process within this test cell. Iron-reducing process caused the preferential removal of certain compounds. Microbial enumeration results show that the distribution of microbial population varied with depth and sediment materials. Lower microbial population was observed in those sections with higher portion of clayey materials. The less permeable materials would limit the bacterial transport, decrease the bioavailability of Fe(III) to iron-reducing bacteria, and thus cause the low biodegradation activity. Results suggest that using blended sediments for biodegradation rate measurements may provide misleading results.}, number={5}, journal={WATER SCIENCE AND TECHNOLOGY}, author={Kao, CM and Kota, S and Ress, B and Barlaz, MA and Borden, RC}, year={2001}, pages={341–348} }
 @article{zenker_borden_barlaz_2000, title={Mineralization of 1,4-dioxane in the presence of a structural analog}, volume={11}, ISSN={["1572-9729"]}, DOI={10.1023/a:1011156924700}, abstractNote={A mixed culture with the ability to aerobically biodegrade 1,4-dioxane in the presence of tetrahydrofuran (THF) was enriched from a 1,4-dioxane contaminated aquifer. This consortium contained 3-4 morphologically different types of colonies and was grown in mineral salts media. Biodegradation of 1,4-dioxane began when THF concentrations in batch experiments became relatively low. No biodegradation of 1,4-dioxane was observed in the absence of THF and the measured cell yield was similar during degradation of 1,4-dioxane with THF or with THF alone. However, when the consortium was grown in the presence of 14C-1,4-dioxane plus THF, 2.1% of the radiolabeled 1,4-dioxane was present in the particulate fraction. The majority of the 14C (78.1%) was recovered as 14CO2, while 5.8% remained in the liquid fraction. This activity is interesting since the non-growth substrate is mineralized, yet only minimally assimilated into biomass. Using THF as the growth substrate, the consortium also degraded 1,3-dioxane, methyl t-butyl ether, ethyl t-butyl ether and t-amyl methyl ether.}, number={4}, journal={BIODEGRADATION}, author={Zenker, MJ and Borden, RC and Barlaz, MA}, year={2000}, pages={239–246} }
 @article{kota_borden_barlaz_1999, title={Influence of protozoan grazing on contaminant biodegradation}, volume={29}, DOI={10.1111/j.1574-6941.1999.tb00609.x}, abstractNote={The influence of protozoan grazing on biodegradation rates in samples from contaminated aquifer sediment was evaluated under aerobic and anaerobic conditions. Predator–prey biomass ratios suggested that protozoan grazing might be influencing bacterial populations. Experiments under aerobic conditions were conducted with a sediment extract fed with BTEX and treated with protozoan inhibitors (cycloheximide, neutral red, amphotericin-B). After 10 days, BTEX losses were enhanced in the presence of protozoan inhibitors, suggesting that reduced protozoan grazing enhanced the rate of BTEX biodegradation. In tests conducted in macrocosms under anaerobic conditions, treatments included benzaldehyde (carbon substrate), benzaldehyde+cycloheximide, a live control (no carbon), and an abiotic control. In both the benzaldehyde-only and benzaldehyde+cycloheximide treatments, repeated benzaldehyde additions resulted in an increase in the total fermenter population from 103 to 105 cells (g sediment)−1 and in the Fe-reducing population from 101 to 105 cells g−1. However, the protozoan population remained at about 20 cells g−1 in the sediment with no cycloheximide, and there was no difference in benzaldehyde biodegradation in the presence and absence of cycloheximide, suggesting that predation was not a significant control on anaerobic benzaldehyde biotransformation.}, number={2}, journal={FEMS Microbiology Ecology}, author={Kota, S. and Borden, R. C. and Barlaz, Morton}, year={1999}, pages={179–189} }
 @book{borden_1998, title={Effect of in-lake processes on pollutant removal in water quality ponds}, number={1998 Apr. 1}, journal={Report (Water Resources Research Institute of the University of North Carolina)}, institution={Raleigh, NC: University of North Carolina Water Resources Research Institute}, author={Borden, R. C.}, year={1998} }
 @article{borden_dorn_stillman_liehr_1998, title={Effect of in-lake water quality on pollutant removal in two ponds}, volume={124}, DOI={10.1061/(asce)0733-9372(1998)124:8(737)}, abstractNote={An extensive field study examined pollutant removal in two regional wet detention ponds near High Point, N.C. Substantial differences in influent pollutant concentrations between the ponds caused significant differences in pond water quality and pollutant removal efficiency. In Davis Pond, influent fecal coliform and nutrient concentrations were high because of several large dairy farms in the watershed, resulting in hypereutrophic conditions as evidenced by high chlorophyll-a concentrations, high midday pH values and supersaturated midday oxygen concentrations. In Piedmont Pond, influent fecal coliform and nutrient concentrations were much lower, resulting in mesotrophic to slightly eutrophic conditions. Both ponds thermally stratified and developed an anaerobic hypolimnion. In Davis Pond, annual pollutant removal efficiencies for total suspended solids, volatile suspended solids, total organic carbon, total phosphorus, dissolved phosphorus, nitrate/nitrite, total ammonia nitrogen, and total nitrogen were 56%, 32%, 15%, 41%, 54%, 16%, 2%, and 11%, respectively. In Piedmont Pond, annual pollutant removal efficiencies were 20%, 30%, 27%, 40%, 15%, 66%, -64%, and 36%, respectively.}, number={8}, journal={Journal of Environmental Engineering (New York, N.Y.)}, author={Borden, R. C. and Dorn, J. L. and Stillman, J. B. and Liehr, S. K.}, year={1998}, pages={737–743} }
 @inproceedings{kota_barlaz_borden_1998, title={Significance of protozoan grazing on the intrinsic bioremediation of gasoline contaminated aquifers}, number={1998 May}, booktitle={1998 Spring Meeting, American Geophysical Union, Boston, MA, May 26-29, 1998}, author={Kota, S. and Barlaz, M. A. and Borden, R. C.}, year={1998} }
 @article{hunt_shafer_barlaz_borden_1997, title={Anaerobic biodegradation of alkylbenzenes in laboratory microcosms representing ambient conditions}, volume={1}, DOI={10.1080/10889869709351317}, abstractNote={Abstract A microcosm study was performed to document the anaerobic biodegradation of benzene, toluene, ethylbenzene, m- xylene, and/or o-xylene in petroleum-contaminated aquifer sediment from sites in Michigan (MI) and North Carolina (NC) and relate the results to previous field investigations of intrinsic bioremediation. Laboratory microcosms, designed to simulate ambient conditions, were constructed under anaerobic conditions with sediment and groundwater from source, mid-plume, and end-plume locations at each site. The general patterns of biodegradation and electron acceptor utilization in the microcosms were consistent with field data. At the MI site, methane was produced after a moderate lag period, followed by toluene degradation in all sets of microcosms. At the NC site, biodegradation of the target compounds was not evident in the source area microcosms. In the mid-plume microcosms, toluene and o-xylene biodegraded first, followed by m-xylene and benzene, a pattern consistent with contaminant deca...}, number={1}, journal={Bioremediation Journal}, author={Hunt, M. J. and Shafer, M. B. and Barlaz, Morton and Borden, R. C.}, year={1997}, pages={53–64} }
 @article{kota_barlaz_borden_1997, title={Benzaldehyde degradation under mixed iron reducing / fermentative conditions}, volume={78}, number={17}, journal={Eos (Richmond, Va.)}, author={Kota, S. and Barlaz, M. A. and Borden, R.C.}, year={1997}, pages={S121} }
 @article{borden_goin_kao_1997, title={Control of BTEX migration using a biologically enhanced permeable barrier}, volume={17}, ISSN={["1745-6592"]}, DOI={10.1111/j.1745-6592.1997.tb01186.x}, abstractNote={Abstract}, number={1}, journal={GROUND WATER MONITORING AND REMEDIATION}, author={Borden, RC and Goin, RT and Kao, CM}, year={1997}, pages={70–80} }
 @article{kao_borden_1997, title={Enhanced biodegradation of BTEX in a nutrient briquet-peat barrier system}, volume={123}, DOI={10.1061/(asce)0733-9372(1997)123:1(18)}, abstractNote={A two-layer barrier system has been developed to remediate gasoline-contaminated ground water. This system consists of a nutrient briquet layer to continuously supply nitrate as the electron acceptor for contaminant biodegradation and a peat layer to remove residual nitrate via biological denitrification and residual contaminants by sorption. Nitrate release rates from three different sizes of concrete briquets were used to estimate parameters for modeling solute diffusion in aggregated porous media with mobile and stagnant pore-water regions. Toluene, ethylbenzene, and xylene (TEX) biodegradation rates in denitrifying microcosms at pH 8 and 9 were lower than in microcosms at pH 7.4. No degradation was observed at pH 10 under denitrifying conditions. A laboratory-scale, permeable barrier system was developed to evaluate TEX removal and to identify any operational problems. Average removal efficiencies were 86% for toluene, 71% for ethylbenzene, 43% for m-xylene, and 28% for o-xylene in the nutrient briquet and downstream soil column over a 45-day operating period. There was no evidence of benzene biodegradation under denitrifying conditions in the batch microcosms or continuous-flow columns.}, number={1}, journal={Journal of Environmental Engineering (New York, N.Y.)}, author={Kao, C.-M. and Borden, R. C.}, year={1997}, pages={18–24} }
 @inproceedings{borden_hunt_shafer_barlaz_1997, title={Environmental research brief}, booktitle={Anaerobic biodegradation of BTEX in aquifer material}, publisher={Ada, OK: U.S. Environmental Protection Agency, Research and Development, National Risk Management Research Laboratory}, author={Borden, R. C. and Hunt, M. J. and Shafer, M. B. and Barlaz, M. A.}, year={1997}, pages={9} }
 @book{borden_dorn_stillman_liehr_1997, title={Evaluation of wet ponds for protection of public water supplies}, number={311}, journal={Report (Water Resources Research Institute of the University of North Carolina)}, institution={Raleigh, NC: University of North Carolina Water Resources Research Institute}, author={Borden, R. C. and Dorn, J. L. and Stillman, J. B. and Liehr, S. K.}, year={1997} }
 @book{kota_hunt_barlaz_borden_1997, title={Factors limiting intrinsic bioremediation of gasoline-contaminated aquifers}, number={1997}, journal={Report (Water Resources Research Institute of the University of North Carolina)}, institution={Raleigh, NC: University of North Carolina Water Resources Research Institute}, author={Kota, S. and Hunt, M. J. and Barlaz, M. A. and Borden, R. C.}, year={1997} }
 @inproceedings{field studies of btex and mtbe intrinsic bioremediation_1997, volume={4654}, booktitle={Field studies of BTEX and MTBE intrinsic bioremediation (API publication; no. 4654)}, publisher={American Petroleum Institute}, year={1997}, pages={198} }
 @article{borden_daniel_lebrun_davis_1997, title={Intrinsic biodegradation of MTBE and BTEX in a gasoline-contaminated aquifer}, volume={33}, ISSN={["1944-7973"]}, DOI={10.1029/97WR00014}, abstractNote={Three‐dimensional field monitoring of a gasoline plume showed rapid decay of toluene and ethylbenzene during downgradient transport with slower decay of xylenes, benzene, and MTBE under mixed aerobic‐denitrifying conditions. Decay was most rapid near the source but slower farther downgradient. Effective first‐order decay coefficients varied from 0 to 0.0010 d−1 for MTBE, from 0.0006 to 0.0014 d−1 for benzene, from 0.0005 to 0.0063 d−1 for toluene, from 0.0008 to 0.0058 d−1for ethylbenzene, from 0.0012 to 0.0035 d−1 for m‐, p‐xylene, and from 0.0007 to 0.0017 d−1 for o‐xylene. Laboratory microcosm studies confirmed MTBE biodegradation under aerobic conditions; however, the extent of biodegradation was limited.}, number={5}, journal={WATER RESOURCES RESEARCH}, author={Borden, RC and Daniel, RA and LeBrun, LE and Davis, CW}, year={1997}, month={May}, pages={1105–1115} }
 @book{kota_hunt_barlaz_borden_1997, title={Intrinsic bioremediation of gasoline-contaminated aquifers: Biodegradation rate measurement and microbial ecology}, number={308}, journal={Report (Water Resources Research Institute of the University of North Carolina)}, institution={Raleigh, NC: University of North Carolina Water Resources Research Institute}, author={Kota, S. and Hunt, M. J. and Barlaz, M. A. and Borden, R. C.}, year={1997}, pages={63} }
 @article{ress_kota_kao_barlaz_borden_1997, title={Microbial and geochemical heterogeneity in gasoline contaminated aquifers undergoing intrinsic bioremediation}, volume={78}, number={17}, journal={Eos (Richmond, Va.)}, author={Ress, B. B. and Kota, S. and Kao, J. and Barlaz, M. A. and Borden, R. C.}, year={1997}, pages={S159} }
 @article{borden_1997, title={Natural attenuation of MTBE and BTEX: How do you accurately predict downgradient transport?}, volume={78}, number={17}, journal={Eos (Richmond, Va.)}, author={Borden, R. C.}, year={1997}, pages={S127} }
 @article{kao_borden_1997, title={Site-specific variability in BTEX biodegradation under denitrifying conditions}, volume={35}, ISSN={["1745-6584"]}, DOI={10.1111/j.1745-6584.1997.tb00087.x}, abstractNote={Abstract}, number={2}, journal={GROUND WATER}, author={Kao, CM and Borden, RC}, year={1997}, pages={305–311} }
 @inproceedings{daniel_borden_1997, title={Spatial variability in intrinsic bioremediation rates: Effect on contaminant transport}, volume={1}, booktitle={In Situ and On Site Bioremediation: Papers from the Fourth International In Situ and On-Site Bioremediation Symposium, New Orleans, April 28-May 1, 1997}, publisher={Columbus: Battelle Press}, author={Daniel, R. A. and Borden, R. C.}, year={1997}, pages={29–34} }
 @article{borden_kao_1992, title={EVALUATION OF GROUNDWATER EXTRACTION FOR REMEDIATION OF PETROLEUM-CONTAMINATED AQUIFERS}, volume={64}, ISSN={["1061-4303"]}, DOI={10.2175/wer.64.1.5}, abstractNote={ABSTRACT: 
Past experience has shown that restoration of an aquifer to drinking water quality by groundwater extraction and surface treatment may require many years of pumping. In this research, a mathematical model of hydrocarbon dissolution is developed to aid in the evaluation of groundwater remediation systems. The model assumes that residual hydrocarbon is distributed between two fractions: (1) a fast fraction in equilibrium with the aqueous phase and (2) a slow fraction in which mass transfer is limited. Relationships for simulating equilibrium partitioning are based on classical liquid‐liquid equilibrium theory. Column experiments were performed to test the model and examine the kinetics of aromatic hydrocarbon dissolution as residual hydrocarbon ages. The hydrocarbon dissolution process included an initial equilibrium period during which dissolved hydrocarbon concentrations were high and roughly constant followed by a rapid drop‐off period and an asymptotic period during which dissolved hydrocarbon concentrations were low and declined slowly. After passing more than 700 pore volumes of water through the column, between 8 and 10% of the original toluene and xylene isomers remained in the column. Model simulations were conducted to evaluate the effect of pulsed pumping on groundwater cleanup time.}, number={1}, journal={WATER ENVIRONMENT RESEARCH}, author={BORDEN, RC and KAO, CM}, year={1992}, pages={28–36} }