Robert Borden
Education
Ph.D. Environmental Engineering Rice University
M.S. Environmental Engineering University of Virginia
B.S. Civil Engineering University of Virginia
Publications
- Evaluating the impact of back diffusion on groundwater cleanup time , JOURNAL OF CONTAMINANT HYDROLOGY (2021)
- A Physically Based Approach for Estimating Hydraulic Conductivity fromHPTPressure and Flowrate , GROUNDWATER (2020)
- Stochastic cost-optimization and risk assessment of in situ chemical oxidation for dense non-aqueous phase liquid (DNAPL) source remediation , STOCHASTIC ENVIRONMENTAL RESEARCH AND RISK ASSESSMENT (2018)
- Laboratory column evaluation of high explosives attenuation in grenade range soils , Journal of Environmental Quality (2017)
- Natural and enhanced attenuation of explosives on a hand grenade range , Journal of Environmental Quality (2017)
- Impact of glycerin and lignosulfonate on biodegradation of high explosives in soil , JOURNAL OF CONTAMINANT HYDROLOGY (2016)
- Statistical Analysis of Secondary Water Quality Impacts from Enhanced Reductive Bioremediation , GROUND WATER MONITORING AND REMEDIATION (2015)
- Perchlorate natural attenuation in a riparian zone , JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH PART A-TOXIC/HAZARDOUS SUBSTANCES & ENVIRONMENTAL ENGINEERING (2014)
- Enhanced Reductive Dechlorination of Tetrachloroethene Dense Nonaqueous Phase Liquid with EVO and Mg(OH)(2) , ENVIRONMENTAL SCIENCE & TECHNOLOGY (2013)
- Power earth auger modification for waste extraction from pit latrines , JOURNAL OF WATER SANITATION AND HYGIENE FOR DEVELOPMENT (2013)
Grants
The overall objective of this proposal is to further develop and demonstrate a process to enhance the sorption and/or degradation of TNT, RDX, HMX and perchlorate in soils by spray application of an amendment solution containing waste glycerol and a soluble humic material to the soil surface, followed by irrigation to carry the amendments deeper into the soil profile. The readily biodegradable glycerol will stimulate anaerobic biodegradation of the target contaminants and will reduce naturally occurring Fe(III) oxides and hydroxides to Fe(II). This Fe(II) will provide a reservoir of reducing power to maintain anoxic conditions in the soil and will enhance abiotic degradation of RDX and other contaminants. The humic materials will also maintain reducing conditions by consuming oxygen, enhance hydrophobic sorption, enhance covalent binding of TNT, and may potentially serve as electron shuttles, enhancing abiotic degradation by Fe(II). The humic material is also expected to enhance sorption of any heavy metals that may be present. Irrigation and transport of the amendments at least 0.25 m into the soil profile will be important to reduce fire hazards, generate more strongly reducing conditions, and increase treatment longevity. Our process builds heavily on prior work supported by SERDP (CU-1229) and ESTCP (ER-0434) which showed that a combined peat ? soybean oil treatment could be effective in reducing contaminant flux through the vadose zone. The major focus of this project will be to develop a practical, easy to deploy technology that does not generate a fire hazard and does not interfere with training activities. In this demonstration, an established and operational burn ground will be treated to reduce concentrations of perchlorate and other energetic compounds in the vadose zone. We propose to follow a phased approach consisting of: (1) laboratory column studies to identify mixtures of glycerol and/or humic materials that are effective in treating contaminated soils in situ and preventing leaching of contaminants deposited in the future; (2) medium scale field-pilot tests to evaluate treatment performance under representative field conditions; and (3) a large scale field demonstration of the technology on a heavily impacted burn area. At the end of each phase, there is a GO/NO GO Decision. Glycerol / humics treatment of soils should be applicable to a wide variety of DoD facilities including mortar and grenade ranges, tank targets, OB/OD areas, etc. This technology is not expected to replace lime treatment of training ranges. Rather, our approach will complement the lime treatment technology and should be applicable to many sites where lime treatment is difficult to implement (soils with high acidity, UXO, vegetated areas, etc.). Cost and performance of the proposed technology are expected to be comparable to lime treatment of surface soils.
Electron donor addition can be very effective in stimulating enhanced reductive dechlorination (ERD) of chlorinated solvents and anaerobic biodegradation/immobilization of other groundwater contaminants. However, electron donor addition can result in the release of a groundwater ?plume? with reduced levels of O2, NO3-, SO42-, and elevated levels of dissolved Mn2+, Fe2+, CH4, organic carbon, salts, and naturally occurring hazardous compounds (As, etc.). There is growing concern about these ?secondary impacts? of anaerobic bioremediation processes. Objective: The overall objective of this research is to develop an improved understanding of the near- and long-term impacts to groundwater quality after implementation of in situ anaerobic bioremediation processes. This will include development and application of a general modeling approach for describing the natural attenuation of important secondary water quality impacts associated with electron donor addition. Specific objectives to be achieved during the three year duration of this project include. A. Formulate a general modeling approach appropriate for simulating the natural attenuation of electron donors and associated secondary impacts for a wide range of sites. The model approach and validation will be based on data from three intensively studied field sites -- Bemidji Crude Oil Spill, Cape Cod Wastewater Plume, and NAWC - West Trenton Chlorinated Solvent Spill. B. Assemble a database of secondary water quality impacts at ERD sites. Analyze the secondary plumes to determine a range of characteristics and natural attenuation mechanisms. Identify a set of representative Case Studies illustrating important aspects of secondary plume behavior. C. Use the validated model approach to simulate a series of synthetic plumes corresponding to end-member cases important to SWQI assessment. Use the simulation results to assess the potential for significant SWQIs at ERD sites based on site characteristics and remediation system design. D. Use the advanced model simulations and ERD parameter database to develop a draft protocol for estimating the likely extent and duration of secondary impacts at typical ERD sites. The protocol would address extent and duration of impacts, sampling needs, and modeling approaches.
Increasing the pH of groundwater and aquifer material is a major challenge due to the high buffering capacity of these materials. In this project, we will develop and evaluate colloidal Mg(OH)2 buffers for increasing aquifer pH. This will include laboratory studies to evaluate transport and geochemical properties followed by field testing to evaluate performance.
In this project, we will develop and test a method for emptying septic tanks, cesspits and latrines in developing countries using a gasoline powered auger that has been modified to operate as a progressive cavity pump. The modified auger/pump will be used to pump a mixture of solids and water into 55 gallon drums that can be carried to a small vehicle for transport to a treatment and disposal facility.
The overall objective of this project is to develop a set of tools to assist design engineers in developing effective, reasonably efficient systems for distributing aqueous amendments for in situ treatment of groundwater contaminants. At this time, the primary applications for the tools will be for design of in situ chemical oxidation systems using permanganate and in situ anaerobic bioremediation systems using soluble substrates and emulsified oil. However, as technology evolves, this general approach should be applicable to distribution of other aqueous amendments. Specific objectives of this project are listed below. 1. Use currently available numerical models to understand the effects of site conditions (e.g. permeability, contaminant distribution, site heterogeneity) and design variables (location of wells, injection rates, volumes, amount of reagent, etc.) on reagent distribution and associated contact efficiency. Develop simple design curves relating reagent distribution efficiency to amount of fluid/reagent injected. To the extent possible, present the results in a non-dimensional form (e.g. ratio of reagent injected to theoretical demand). 2. Develop a simple, spreadsheet-based design tool to assist junior to mid-level engineers in planning injection systems for in situ aquifer treatment with MnO4-, soluble substrates and emulsified oil. This design tool will allow designers to evaluate the effect of different design variables (well spacing, amount of reagent, injection rate, etc.) on remediation system cost and expected performance. Different worksheets will be developed for each of the major design alternatives (e.g. type of reagent and type of injection system). Experienced users who have already compiled the input data for their site (e.g. permeability, natural oxidant demand, contaminant concentrations) should be able to develop a preliminary design for one alternative (e.g. 5-spot injection grid with MnO4-) in about an hour. 3. Develop materials to train junior to mid-level engineers with no modeling experience in the use of the design tool. These materials will consist of: (a) a detailed guidance manual; and (b) a series of 15 to 30 minute PowerPoint tutorials that walk new users through each worksheet. Chemical oxidation and anaerobic bioremediation are being used to treat thousands of DoD and private sites. At some sites, the process works very well, resulting in substantial reductions in contaminant concentration and mass. However at too many sites, the remediation process does not meet cleanup objectives. We believe the most common problem is poor delivery of the chemical reagent to the treatment zone. If we can provide design engineers, with a simple, easy to use tool for planning aqueous injection systems, we can substantially improve the performance and reduced costs at DoD sites.
In this project, we will develop and evaluate low cost, soluble substrates for enhanced anaerobic bioremediation of chlorinated solvents and related contaminants.
The overall objective of this project is to determine the relationships of sample processing procedures to the effectiveness and efficiency of three molecular techniques used in qualitative and quantitative analysis of microbial populations in groundwater and associated saturated soil samples.
We have been studying the use of emulsified soybean oil for soil and groundwater remediation for several years. This research has dramatically improved our understanding of how soybean oil is distributed in the subsurface and how it stimulates pollutant biodegradation. In this project, we will evaluate the use of soy flour, soy protein concentrate, and lecithin as alternative materials for production of an emulsified soybean oil product for anaerobic bioremediation.
In this project, we will develop and test a process to treat vadose zone contamination at mine sites using crude glycerol. In this process, crude caustic glycerol generated during production of biodiesel would be diluted with mine water and sprayed on the surface of the tailings pile. As the glycerol infiltrates down through the pile, the AMD would be treated through two complementary processes: (a) neutralization of the sulfuric acid present in the AMD by residual NaOH present in the glycerol; and (b) anaerobic biodegradation of the sulfate producing sulfide.
Ore Knob Branch and Peak Creek are impaired due to discharge of acid mine drainage (AMD) from an abandoned copper/zinc mine. AMD production from the large tailings impoundment will be controlled by injecting emulsified soybean oil into the sediments to stimulate growth of naturally occurring bacteria. These bacteria will then use the soybean oil as a food source, consuming any dissolved oxygen and stopping further AMD production. Once oxygen is depleted, the sulfate reducing bacteria will reduce sulfuric acid (H2SO4) to sulfide (HS-). Metals will then coprecipitate with HS-, returning the minerals back to their original insoluble form (FeS2, CuS, NiS, ZnS, etc.). Extensive laboratory studies have demonstrated that this approach is very effective in treating AMD, resulting in a dramatic increase in pH, and reduction in dissolved metals. However, a pilot test should be conducted before full scale application.
We have an opportunity to demonstrate the use of emulsified soybean oil at a major acid mine drainage (AMD) site in western North Carolina. The site is a former copper/zinc mine that has severely polluted almost 4 miles of stream feeding the New River. We propose to treat AMD discharging from the site by injecting emulsified soybean oil directly into the tailings pile. Bacteria present within the tailings will use the soybean oil as food while reducing sulfuric acid to sulfide. The sulfide will react with heavy metals and precipitate out of solution. In this way, the AMD will be treated inside of the tailings pile, with no above ground equipment or costs.
Laboratory microcosm studies will be conducted using sediment and groundwater from the Maryland Sand, Gravel and Stone (MSGS) site to: (a) identify factors limiting contaminant biodegradation; and (2) identify treatment(s) that can be evaluated at the pilot scale to increase naturally occurring rates of biodegradation.