Sites In Houston Research Articles

Partitioning of Arsenic Species in Fine-Grained Soils

It has been theoretically and experimentally shown that rate-limited sorption/desorption can have a profound effect upon the transport of sorbing contaminants. The advection/dis-persion equation that has been traditionally used to model contaminant transport uses a retardation factor to account for sorption, thereby implicitly assuming local equilibrium between contaminant in the sorbed and aqueous phases. This assumption fails to consider the possibly large effects of rate-limited sorption/desorption. The mass release characteristic of arsenic-contaminated soils at the Crystal Chemical site in Houston, TX, was examined. Soils were collected from beneath two former waste-water ponds that were the source of arsenic in the uppermost aquifer. Samples were typical of those found within the fine-grained components of local alluvial overbank deposits that comprise the bulk of the site. The dynamic test applied a continuing head of water, operating in an upflow mode, through 4-inch-diameter by 12-inch-long soil columns repacked to in-situ density. Three columns were constructed The mass release characteristic of arsenic-contaminated soils at the Crystal Chemical site in Houston, TX, was examined. Soils were collected from beneath two former waste-water ponds that were the source of arsenic in the uppermost aquifer. Samples were typical of those found within the fine-grained components of local alluvial overbank deposits that comprise the bulk of the site. The dynamic test applied a continuing head of water, operating in an upflow mode, through 4-inch-diameter by 12-inch-long soil columns repacked to in-situ density. Three columns were constructed— two containing predominantly clay, and the other containing clayey silt. Leachate from the most permeable column was collected over 42 pore volumes (equivalent to 120 years of extraction). Sharp declines in arsenic concentrations in the leachate were measured after just four pore volumes. A biphasic response was evident, consistent with published research on kinetically limited mass transfer of retarding solutes. The most responsive column was pulsed to elucidate the effects of diffusion and pulsed pumpingtwo containing predominantly clay, and the other containing clayey silt. Leachate from the most permeable column was collected over 42 pore volumes (equivalent to 120 years of extraction). Sharp declines in arsenic concentrations in the leachate were measured after just four pore volumes. A biphasic response was evident, consistent with published research on kinetically limited mass transfer of retarding solutes. The most responsive column was pulsed to elucidate the effects of diffusion and pulsed pumping. Arsenic concentrations returned to baseline levels in less than three pore volumes. These studies ultimately led to a joint assessment between Southern Pacific Lines (SPL) and EPA Region VI, which concluded that extraction and treatment of the shallow aquifer beneath the site was not feasible, in light of the aggressive restoration goal.

Storage Coefficients and Vertical Hydraulic Conductivities in Aquitards Using Extensometer and Hydrograph Data

AbstractA method is presented to estimate elastic and inelastic specific storage and vertical hydraulic conductivities in aquitards in multilayered flow systems. Borehole extensometer records and ground‐water hydrographs from piezometers are used to construct plots of effective stress and deformation. Elastic and inelastic specific storage are estimated from the plots of effective stress and deformation during loading and unloading cycles. The elapsed loading time is estimated from the same plots and is used to calculate vertical hydraulic conductivity using Terzaghi's consolidation theory. The method is applied to three sites in Houston, Texas.

An analysis of the trend in ground-level ozone using non-homogeneous poisson processes

This paper provides a method for measuring the long-term trend in the frequency with which ground-level ozone present in the ambient air exceeds the U.S. Environmental Protection Agency's National Ambient Air Quality Standard (NAAQS) for ozone. A major weakness of previous studies that estimate the long-term trend in the very high values of ozone, and therefore the long-term trend in the probability of satisfying the NAAQS for ozone, is their failure to account for the confounding effects of meterological conditions on ozone levels. Meteorological variables such as temperature, wind speed, and frontal passage play an important role in the formation of ground-level ozone. A non-homogenous Poisson process is used to account for the relationship between very high values of ozone and meteorological conditions. This model provides an estimate of the trend in the ozone values after allowing for the effects of meteorological conditions. Therefore, this model provides a means to measure the effectiveness of pollution control programs after accounting for the effects of changing weather conditions. When our approach is applied to data collected at two sites in Houston, TX, we find evidence of a gradual long-term downward trend in the frequency of high values of ozone. The empirical results indicate how possibly misleading results can be obtained if the analysis does not account for changing weather conditions.

An analysis of the long-term trend in ozone data from two Houston, Texas monitoring sites

This paper uses the theory of extreme values to estimate the long-term trend in the probability that ozone measurements made at two monitoring sites in Houston, TX exceed a threshold level specified by the U.S. Environmental Protection Agency (EPA). In addition, a bootstrap testing procedure is used to test if the trend is statistically significant. The analysis takes into account the correlation in the series of daily ozone readings, seasonality in the data, and missing values in the ozone series. The empirical results indicate a downward trend in the probability of exceeding the EPA's specified threshold level at both sites. However, the magnitude of the downward trend is much greater at one site than at the other, even though both sites are in Houston. In fact, hypothesis testing results suggest that only one site has a statistically significant trend in the long-term probability of an exceedance.

Cyclic Lateral Loading of a Large‐Scale Pile Group

A large‐scale group of nine steel‐pipe piles in a closely‐spaced arrangement was subjected to two‐way, cyclic, lateral loading with water above the ground surface. The test was conducted in stiff, overconsolidated clay at a site in Houston, Texas. All of the piles in the group were extensively instrumented to allow the results to be compared with those from other piles in the group and from the testing of an isolated, single pile. The results emphasize the highly nonlinear nature of the pile‐soil‐pile interaction. A substantial reduction in ultimate soil resistance was measured in the group piles relative to that of a similarly loaded single pile for both the first cycle and for 100 cycles of load.

Quieting Reform: Social Science and Social Action in an Urban Youth Program

Quieting Reform is a complex, multilayered case study of a federally sponsored evaluation of a federally supported social reform effort, the Cities-in-Schools (CIS) program. In the book, Robert Stake tells a detailed, candid story which is part metaevaluation, part methodological advocacy, and part social inquiry. He writes an insightful, biased, and complicated account of a complex event: the CIS program evaluation. CIS was an urban education and social services program designed to identify and help the most alienated ghetto youths. Schools and human service agencies were to provide coordinated educational, health, and legal assistance through intensive personal attention and social group support. Academic progress focused on the improvement of reading skills, but the ultimate goal was for the youths .... to become educated and employed, legally respectable and humane (p.5). At the time of the evaluation, the CIS program was especially active in New York City, Atlanta, and Indianapolis, with other sites in Houston, Oakland, and Washington, D.C. The program had the public support of President and Mrs. Carter and had received over $10,000,000 in federal funds by May of 1982. Based on a web of personal and political motivations which Stake traces, the CIS program was evaluated from 1978 to 1981 by the American Institutes for Research (AIR), with Charles Murray as principal investigator. The evaluation was funded by the National Institute of Education (NIE) where Norman Gold, the NIE project monitor, acted as a strict overseer of the design and implementation of the evaluation study, insisting on the use of a approach. NIE further required that a Technical Review Panel, comprised of nationally known social scientists in evaluation, be established to monitor and advise the ongoing evaluation work. During this time, NIE also originated and funded other field studies of the stakeholder approach. Stake was initially a member of the AIR Technical Review Panel but resigned in order to write this investigative case study as a part of these other NIE field study efforts. In the book's five chapters, Stake describes, interprets, and evaluates, focusing on the origins and nature of the CIS program (Chapter 1), the AIR evaluation design and the Technical Review Panel (Chapter 2), the implementation, modification, and yield of the evaluation work (Chapter 3), how various individuals and groups perceived and judged the evaluation (Chapter 4), and the final impact of the evaluation on knowledge production, evaluation practice, and social reform (Chapter 5). From extensive interviews, discussions, observations, and document reviews, Stake attempts to portray the context, participants, events, and outcomes of both the CIS program and its evaluation. A basic problem in judging this volume is

Comparative Site Evaluations for Locating a High-Energy Physics Lab in Texas

In 1984, the Texas Legislature funded a four-university, interdisciplinary effort to identify feasible sites for location of a very high-energy physics lab in Texas and to evaluate the comparative advantages of one site versus another. Six feasible sites were identified and a comparative site analysis was made by applying Data Envelopment Analysis (DEA), incorporating project cost, user time delay, and environmental impact data. In addition, for the efficient sites, the price weights for user time delay and environmental impact, given normalization on project cost, were analyzed and arguments were developed to bracket these pairs of price weights into an “assurance region” for the preferred site(s). The South Dallas site was found to be preferred for a wide range of conditions, while the North Houston site was sensitive to the method of indexing the impact of the environment. The method appears to be applicable to a wide range of siting problems faced by not only government, but also industry.

Centrifugal modeling of pile foundations : Ko, H Y; Atkinson, R H; Goble, G G; Ealy, C D Proc of the Conference on Analysis and Design of Pile Foundations, San Francisco, California, 1–5 Oct 1984P21–P40. Publ New York: ASCE, 1984

Modeling of pile foundations in a centrifuge, where the self weight induced stresses in the soil are simulated by elevated gravity loading, is described. Hollow pipe piles in a stiff clay were tested in simulation at the University of Houston site. Tapered timber piles in sand were tested in simulation at the Locks and Dam No. 26 site. Effects of inflight installation, soil properties and soil saturation were studied.

Does It Pay to Plan Suburban Growth?

This article compares the economic results of planned community development with those of unplanned development for a 7,500-acre site in Houston, Texas. The comparison indicates that planned development produces higher net benefits than unplanned development does for all three cost areas investigated-land development costs, transportation costs, and social costs-and that the difference in benefits is greatest in the area of transportation costs. The magnitude of the difference is small, however-on the order of 1 percent to 3 percent of total costs. The results raise questions about how high the costs of sprawl development really are, but suggest where efforts to reduce those costs can be the most beneficial, particularly in transportation planning.

Geotechnical Characterization of Desiccated Clay

Conventional testing procedures produce scatter and bias in indicated properties of soils, such as desiccated clays. This paper describes and compares several conventional and non-conventional methods for characterizing the engineering properties of such soils at a site in Houston, Texas. Properties considered include undrained shear strength, stress-deformation moduli, earth pressure coefficients, and compression indexes. Similarities and differences between soil preconsolidated by desiccation and by stress removal are noted.

Correlation of mutagenic assessment of Houston air particulate extracts in relation to lung cancer mortality rates

Air particulate extracts from a series of solvents were tested in the Ames mutagen detection system and were found to be mutagenic in varying degrees as a function of the particulate collection site in Houston, Texas. The mutagenicity level at seven sites was compared with age-adjusted mortality rates in the same areas. Significant correlation was found with the lung cancer mortality rates but not with mortality rates for other causes. These findings support the hypothesis of a contribution of urban air particulate to the lung cancer rates. Furthermore, these findings suggest that an index of the mutagenicity of air particulate is a more powerful measure of the human health hazard of air pollution than the traditional indices of particulate concentration.