Jeffrey Evans - Academia.edu (original) (raw)

Papers by Jeffrey Evans

Black or African American. A person having origins in any of the black racial groups of Africa. N... more Black or African American. A person having origins in any of the black racial groups of Africa. Native Hawaiian or Other Pacific Islander. A person having origins in any of the original peoples of Hawaii, Guam, Samoa, or other Pacific Islands. White. A person having origins in any of the original peoples of Europe, the Middle East, or North Africa. WHY THIS INFORMATION IS BEING REQUESTED: The Federal Government has a continuing commitment to monitor the operation of its review and award processes to identify and address any inequities based on gender, race, ethnicity, or disability of its proposed PIs/PDs. To gather information needed for this important task, the proposer should submit a single copy of this form for each identified PI/PD with each proposal. Submission of the requested information is voluntary and will not affect the organization's eligibility for an award. However, information not submitted will seriously undermine the statistical validity, and therefore the usefulness, of information recieved from others. Any individual not wishing to submit some or all the information should check the box provided for this purpose. (The exceptions are the PI/PD name and the information about prior Federal support, the last question above.) Collection of this information is authorized by the NSF Act of 1950, as amended, 42 U.S.C. 1861, et seq. Demographic data allows NSF to gauge whether our programs and other opportunities in science and technology are fairly reaching and benefiting everyone regardless of demographic category; to ensure that those in under-represented groups have the same knowledge of and access to programs and other research and educational oppurtunities; and to assess involvement of international investigators in work supported by NSF. The information may be disclosed to government contractors, experts, volunteers and researchers to complete assigned work; and to other government agencies in order to coordinate and assess programs. The information may be added to the Reviewer file and used to select potential candidates to serve as peer reviewers or advisory committee members.

Civil Engineering, 1990

The methods of dealing with hazardous waste are evolving. At Superfund sites, for instance, excav... more The methods of dealing with hazardous waste are evolving. At Superfund sites, for instance, excavation and removal was once the popular choice for treating pollutants, but stabilization and solidification has now emerged as a viable option. The key to waste stabilization is to produce a material that minimizes the leaching rate of hazardous pollutants. Conventional agents, such as cement, cement kiln dust or fly ash, are successful in stabilizing metal-bearing wastes, but they are generally less effective when used exclusively with organic wastes. New organically modified clays, however, can help solve the problem. When these clays are mixed with conventional stabilization agents, they adsorb and retain pollutants while solidifying organic wastes into a stable mass. Waste stabilization is not the only environmental application for organically modified clays. They're on the market for water treatment, and they have shown potential for spill control and as tank and landfill liners...

Transportation Research Record, 1989

Organically modified clays are prepared by replacing the exchangeable inorganic cations present i... more Organically modified clays are prepared by replacing the exchangeable inorganic cations present in the natural clays. Organic cations used in this replacement process are then able to adsorb other organic compounds. Thus, an organically modified clay can adsorb organic constituents that are otherwise unaffected or possibly adversely affected by unmodified clays. Organically modified clays may be mixed with additional stabilization agents (such as cement, cement kiln dust, or fly ash) to solidify contaminated soils or organic wastes into a stable mass. The stabilized mass has improved bearing properties and a reduced potential for leaching hazardous constituents into the environment. Because organically modified clays swell in the presence of organic fluids, such as gasoline or fuel oil, they may also be used as sorbents in spill control or in liners for fuel oil tank containment areas. The sorption capabilities of a number of both unmodified and organically modified clays are compared. Data are also presented on the use of organically modified clays for organic sludge stabilization. The findings indicate the feasibility of stabilization technology for remediation of organically contaminated sites as compared with the excavate-and-remove option. The adsorption of organics by organically modified clays is critical to this process.

GeoCongress 2008, 2008

Geo-Challenge is a student competition that has been held at the two most recent ASCE GeoInstitut... more Geo-Challenge is a student competition that has been held at the two most recent ASCE GeoInstitute national meetings (i.e., GeoFrontiers 2006 and GeoDenver 2007). In this event, students design and build a mechanically stabilized earth (MSE) wall in a plywood box using posterboard for the facing, paper for the reinforcing strips, and sand for the backfill. Geo-Challenge has been a successful co-curricular activity but also presents a tremendous opportunity for active learning if incorporated in the geotechnical engineering curriculum. For example, Geo-Challenge is now a standard assignment in the Ground Improvement Engineering course at Bucknell University. In this course, students first study the principles of MSE as part of the lecture series and then compete in Geo-Challenge as part of the laboratory series. The competition has been held twice at Bucknell University and has proven to be an excellent tool for active learning that also is useful for addressing ABET outcomes associated with students' ability to (1) design and conduct experiments, (2) design a system, (3) work effectively in a collaborative environment, and (4) provide effective written communication. This paper presents the details of the Bucknell Geo-Challenge assignment and describes the benefits of Geo-Challenge as a regular curricular activity.

Soil Improvement, 2007

The conventional slurry trench method of construction to form low-permeability vertical barriers ... more The conventional slurry trench method of construction to form low-permeability vertical barriers of soil-bentonite (SB), cement-bentonite (CB) and slag-CB have been widely used. More recently, in situ mixing methods to construct vertical barriers, such as deep mixing method (DMM) and the Trench Remixing and Deep wall method (TRD) have found increased usage. For the first TRD project in the United States, the method has been used for construction of test cells and is under consideration for the construction of a soil mixed barrier wall to prevent the intrusion of salt water into fresh ground water aquifers at the Alamitos Gap in southern California. To fully investigate the technology and its suitability for the application under consideration, laboratory and field studies (including construction and evaluation of two test cells) were conducted. This paper presents the results of various material formulations upon properties such as hydraulic conductivity and unconfined compressive strength. Laboratory studies demonstrated that mixtures of site soils containing saline pore water and blends of clay-water slurry, slag and Portland cement could be developed having measured values of hydraulic conductivity less than 1x10 -7 cm/s and being resistant to long-term degradation in the presence of the saline ground water.

Journal of Geotechnical and Geoenvironmental Engineering, 2005

ABSTRACT In both the United States and the United Kingdom, slurry walls are used as vertical barr... more ABSTRACT In both the United States and the United Kingdom, slurry walls are used as vertical barriers to control groundwater flow and to contain contaminants as part of waste containment systems. In the United States, slurry walls are commonly constructed using soil-bentonite (SB) and the barrier typically consists of a mixture of select soil, bentonite, and bentonite-water slurry. Alternatively, in the United Kingdom, the barrier wall comprises a mixture of cement, blast furnace slag, and bentonite-water slurry. After a comparison of the two techniques, this paper presents the results of permeability and unconfined compressive strength tests on twenty-one different mixtures of slag-cement-bentonite (slag-CB). The slurry wall materials tested in this study were prepared using sample formulations originating in the United Kingdom and materials originating in the United States. Unconfined compression tests were performed on samples after one month of curing, while permeability tests were performed after one, two, three, six, and twelve months of curing. For the mixtures tested and cured twelve months, two mixtures (one having 20% cementitious material with 70% slag replacement and another having 15% cementitious material with 80% slag replacement) were found to have the lowest hydraulic conductivity (2 x 10(-8) cm/s). The data show that 0 to 60% slag replacement had little effect on hydraulic conductivity of the resulting slag-CB mixtures. However, the hydraulic conductivity drastically decreases as the slag replacement increases from 70 to 80%. As expected, the unconfined compressive strength increased as the cementitious material content increased from 10 to 15 to 20%. The slag-CB consolidates rapidly and has compression characteristics similar to other high moisture materials.

Journal of Geotechnical and Geoenvironmental Engineering, 2006

Membrane Behavior of Two Backfills from Field-Constructed Soil-Bentonite Cutoff Walls. [Journal o... more Membrane Behavior of Two Backfills from Field-Constructed Soil-Bentonite Cutoff Walls. [Journal of Geotechnical and Geoenvironmental Engineering 132, 1243 (2006)]. John T. Henning, Jeffrey C. Evans, Charles D. Shackelford. Abstract. ...

Advanced Triaxial Testing of Soil and Rock

As a consequence of hazardous and toxic waste disposal in the subsurface environment, triaxial pe... more As a consequence of hazardous and toxic waste disposal in the subsurface environment, triaxial permeability and strength tests on contaminated soils or with hazardous pore fluids must be conducted for extended time periods. The determination of hydraulic conductivity and shear strength of contaminated soils (or of uncontaminated soils using contaminated permeants) requires equipment and procedures different from those required for conventional triaxial permeability and strength testing. The application of a back pressure works well to maintain saturation for short-term testing but may be insufficient for long-term testing. Procedure and equipment modifications are required to maintain saturation. Reservoir modifications may be made to dissolve contaminants at the solubility limit. Frequent replacement of influent permeant may maintain saturation and influent equilibrium. Equipment modifications may be required due to the chemical nature of the permeant and its incompatibility with the equipment. Long-term testing variables also include gradient, effective stress, particle migration, differential consolidation, diffusion through the membrane, and changes in water chemistry. Due to the need to permeate the specimen with at least one pore volume of permeant, gradients higher than those typically encountered in the field are used. This results in high effective stresses and differential consolidation. The volatile nature of certain permeants may cause diffusion through the membrane and changes in influent chemistry throughout the test.

Journal of the Geotechnical Engineering Division, 1982

A soil-bentonite slurry trench cutoff wall was installed as part of landfill improvements at the ... more A soil-bentonite slurry trench cutoff wall was installed as part of landfill improvements at the Macon County Landfill located in Decatur, Illinois. In order for a soil-bentonite barrier to be continuous and defect-free, a homogeneous, well-graded backfill needs to displace the slurry used to maintain trench stability. Historically, specifications required that the backfill have a unit weight of 15 pounds per cubic foot (pcf) higher than the unit weight of the in-trench slurry and the slurry have a maximum density of 85 pcf. More recently, specifications have also required that the sand content of the slurry, not exceed 10 to 15%. During the course of construction, difficulties arose which gave rise to post-construction investigations of the integrity of the completed cutoff wall. A program of field sampling and testing, which included Osterberg sampling, modified Osterberg sampling, and sonic-core borings, was developed to investigate the integrity of the wall. Since state-of-the-practice quality assurance and quality control measures are based upon field measurements and sampling during construction coupled with laboratory measurements of field-prepared backfill samples, detailed investigations of the in-situ, as-constructed wall are relatively uncommon and even more uncommonly documented in the literature. This paper presents these investigations, findings, conclusions derived from the investigations and provides recommendations for slurry wall design and construction derived from these studies.

Slurry trench cutoff walls have been used as vertical barriers in the rehabilitation of land disp... more Slurry trench cutoff walls have been used as vertical barriers in the rehabilitation of land disposal sites to mitigate subsurface contaminant transport and permit safe reuse of the site. This paper presents two detailed case studies where soil bentonite slurry trench cutoff walls have been used for the rehabilitation of existing land disposal sites. The first case study, a hazardous waste land disposal site, was successfully closed and subsurface migration of contaminants to offsite receptors was controlled by a subsurface vertical barrier installed using the slurry trench method of construction. Portions of the site have been converted to a golf course. This second case study, a municipal and industrial waste landfill, was originally the site of a sand and gravel quarry. Using a soil-bentonite slurry trench cutoff wall, the existing landfill was contained to prevent the spread of ground water contamination and converted into an industrial use. Specifically, the site cap cover was ...

In the current edition of the Body of Knowledge, the Civil Engineering profession recognizes the ... more In the current edition of the Body of Knowledge, the Civil Engineering profession recognizes the careers of the future civil engineer need to be underpinned by education in the humanities and social sciences as well as mathematics and natural sciences. While civil engineering is a technical discipline and the strong technical education must continue, two new program outcomes, one each in humanities and social sciences have been included. The inclusion of these two outcomes in the second edition of the Body of Knowledge now makes explicit that the contributions of civil engineers are largely to and for human society. Humanities include subjects such as art, philosophy and literature while social sciences include subjects such as political science, economics, sociology and psychology. But how is education in social sciences and humanities currently incorporated into a student’s undergraduate education? This paper compares and analyzes the approach to humanities and social science educ...

Hydraulic Conductivity and Waste Contaminant Transport in Soil

Vertical cutoff walls have been used to control the movement of contaminants and contaminated gro... more Vertical cutoff walls have been used to control the movement of contaminants and contaminated groundwater since the remediation of contaminated sites began. There are, however, significant hydraulic conductivity differences between soil-bentonite, cement-bentonite, plastic concrete, and in situ mixed cutoff walls. The results of laboratory and field studies were assessed to show the influence of material properties, confining stress, permeameter type, water table position, and state of stress, on the hydraulic conductivity of vertical cutoffs. The results of these studies show the range of hydraulic conductivity expected for each of the cutoff wall types. Increasing confining stress markedly decreases the hydraulic conductivity of soil-bentonite and has a measurable but reduced impact on stronger backfill materials. Studies on soil-bentonite cutoff walls show that the stress at depth is less than predicted using the effective weight of the overlying materials. This reduction in stress is a result of soil-bentonite materials "hanging-up" on the side walls of the trench. Thus, applying the effective stress calculated from the effective weight of the overlying backfill overestimates the stress to be used in the laboratory tests and results in unconservative measures of hydraulic conductivity. Field data also reveals that, with time, the hydraulic conductivity of soil-bentonite above the water table may increase substantially. Further, the hydraulic conductivity does not significantly decrease upon re-saturation.

Soil bentonite (SB) slurry trench cutoff walls are widely used to control the movement of ground ... more Soil bentonite (SB) slurry trench cutoff walls are widely used to control the movement of ground water and subsurface contaminants. This paper presents findings from in situ tests conducted on an SB wall using the Marchetti Dilatometer Test (DMT). This paper also describes a modified lateral squeezing model that accounts for loading associated with a dike built shortly after construction of the wall was completed. Data from the DMT were obtained during slurry wall construction as well as three, six, and nine months after construction to evaluate changes in the lateral stress state with time. The dilatometer provided a unique opportunity for relatively direct measurement of the in situ horizontal earth pressure. The DMT was conducted in both perpendicular and parallel orientations (relative to the trench line) to investigate stress anisotropy within the wall. Dilatometer data revealed modest differences in the lateral stress state as a function of both orientation and time. The trans...

Canadian Geotechnical Journal, 2011

The potential for changes in hydraulic conductivity, k, of two model soil-bentonite (SB) backfill... more The potential for changes in hydraulic conductivity, k, of two model soil-bentonite (SB) backfills subjected to wet-dry cycling was investigated. The backfills were prepared with the same base soil (clean, fine sand) but different bentonite contents (2.7 and 5.6 dry wt.%). Saturation (S), volume change, and k of consolidated backfill specimens (effective stress, 24 kPa) were evaluated over 3-7 cycles in which the matric suction, Jm, in the drying stage ranged from 50 to 700 kPa. Both backfills exhibited susceptibility to degradation in k caused by wet-dry cycling. Mean values of k for specimens dried at Jm = 50 kPa (S = 30%-60% after drying) remained low after two cycles, but increased by 5-300-fold after three or more cycles. Specimens dried at Jm ≥ 150 kPa (S < 30% after drying) were less resilient and exhibited 500-to 10 000-fold increases in k after three or more cycles. The greater increases in k for these specimens correlated with greater vertical shrinkage upon drying. The findings suggest that increases in hydraulic conductivity due to wet-dry cycling may be a concern for SB vertical barriers located within the zone of a fluctuating groundwater table.

2017 ASEE Annual Conference & Exposition Proceedings

is the Robert L. Rooke Professor of chemical engineering. She earned her B.S. in chemical enginee... more is the Robert L. Rooke Professor of chemical engineering. She earned her B.S. in chemical engineering from Cornell University, and her M.S. and Ph.D., also in chemical engineering, from the University of Virginia. Her primary research focus is on engineering pedagogy at the undergraduate level. She is particularly interested in active, collaborative, and problem-based learning, and how these can be applied to improve conceptual learning. She is also interested in the ways hands-on activities and technology in general and games in particular can be used to improve student engagement.

2007 Annual Conference & Exposition Proceedings

The American Society of Civil Engineers has identified a Body of Knowledge (BOK) and is in the pr... more The American Society of Civil Engineers has identified a Body of Knowledge (BOK) and is in the process of developing a second version. The first BOK identified the requirement for a broad education, and the second BOK will provide further structure to this aspect of civil engineering education. This paper explores the role of humanities and social sciences in the education of a 21 st century engineer. Humanities and social sciences along with mathematics and natural science are at the core of liberal learning. The humanities include subjects such as art, history and literature while social science includes subjects such as economics, political science, sociology and psychology. Traditional engineering education emphasizes mathematics and sciences, but the role of humanities and social sciences is not well understood and appreciated by many students and faculty. In summary, a broad education is necessary for 21 st century civil engineers to think critically about issues confronting them and develop solutions that are informed not only by math, science and engineering, but by humanities and social sciences as well; to Page 12.1461.2 implement those solutions effectively within real social contexts; and to evaluate them in humanistic as well as technical terms.