Stephen Zemba - Academia.edu (original) (raw)

Papers by Stephen Zemba

Journal of Hazardous Materials

iii 8.1.2 Alternate treatments of COPCs below detection limits in stack tests. . 8-3 8.1.3 MACT-b... more iii 8.1.2 Alternate treatments of COPCs below detection limits in stack tests. . 8-3 8.1.3 MACT-based vs. measured emission rates. .

Chapter 1 Introduction 1.1 Importance and Effects of Ozone 7 1.2 Basic Atmospheric Chemistry and ... more Chapter 1 Introduction 1.1 Importance and Effects of Ozone 7 1.2 Basic Atmospheric Chemistry and Modeling 11 1.3 Approach and Aims of this Dissertation 16 Chapter 2 Emissions and Measurements 2.1 Emission Inventories 2.2 Measurements 2.2.1 Diurnal Patterns of NO 2 and Ozone 2.2.2 Seasonal and Night/Day Differences in NO 2 and Ozone 2.2.3 Spatial Measurement Patterns NO 2 Regional Distributions Ozone Regional Distributions 2.2.4 Ozone Averages 2.2.5 Empirical Relation of NO 2 and Ozone Concentrations 43 Chapter 3 Numerical Dispersion Modeling 97 3.1 Model Equations 97 3.2 Numerical Techniques 101 3.3 Model Applications and Testing

Mobile source air toxics (MSATs) are substances that are emitted from motor vehicle and other mob... more Mobile source air toxics (MSATs) are substances that are emitted from motor vehicle and other mobile source exhaust that have been identified as “hazardous air pollutants” with potential human health risks. Numerous MSATs have been identified with varying degrees of scientific knowledge and uncertainty over their health impacts. There currently are no regulations specifying either maximum levels of MSATs in vehicle exhaust, or maximum MSAT ambient concentrations. MSATs continue to be raised as concerns, however, in environmental impact studies for transportation projects. Responding to such concerns, the Federal Highway Administration (FHWA) has provided guidance on addressing MSATs in highway project environmental documentation prepared pursuant to the National Environmental Policy Act (NEPA). The U.S. Environmental Protection Agency’s (EPA's) MOVES emission factor model expands the number of MSATs that can be modeled, encompassing those that have been identified as being most ...

The information contained in this document was taken directly from the submission of the author(s... more The information contained in this document was taken directly from the submission of the author(s). This material has not been edited by TRB. The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished scholars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. On the authority of the charter granted to it by the Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scientific and technical matters. Dr. Ralph J. Cicerone is president of the National Academy of Sciences. The National Academy of Engineering was established in 1964, under the charter of the National Academy of Sciences, as a parallel organization of outstanding engineers. It is autonomous in its administration and in the selection of its members, sharing with the National Academy of Sciences the responsibility for advising the federal government. The National Academy of Engineering also sponsors engineering programs aimed at meeting national needs, encourages education and research, and recognizes the superior achievements of engineers. Dr. Charles M. Vest is president of the National Academy of Engineering. The Institute of Medicine was established in 1970 by the National Academy of Sciences to secure the services of eminent members of appropriate professions in the examination of policy matters pertaining to the health of the public. The Institute acts under the responsibility given to the National Academy of Sciences by its congressional charter to be an adviser to the federal government and, on its own initiative, to identify issues of medical care, research, and education. Dr. Harvey V. Fineberg is president of the Institute of Medicine. The National Research Council was organized by the National Academy of Sciences in 1916 to associate the broad community of science and technology with the Academy's purposes of furthering knowledge and advising the federal government. Functioning in accordance with general policies determined by the Academy, the Council has become the principal operating agency of both the National Academy of Sciences and the National Academy of Engineering in providing services to the government, the public, and the scientific and engineering communities. The Council is administered jointly by both Academies and the Institute of Medicine. Dr. Ralph J. Cicerone and Dr. Charles M. Vest are chair and vice chair, respectively, of the National Research Council. The Transportation Research Board is one of six major divisions of the National Research Council. The mission of the Transportation Research Board is to provide leadership in transportation innovation and progress through research and information exchange, conducted within a setting that is objective, interdisciplinary, and multimodal. The Board's varied activities annually engage about 7,000 engineers, scientists, and other transportation researchers and practitioners from the public and private sectors and academia, all of whom contribute their expertise in the public interest. The program is supported by state transportation departments, federal agencies including the component administrations of the U.S. Department of Transportation, and other organizations and individuals interested in the development of transportation. www.TRB.org www.national-academies.org Table 1. Summary of Most Promising Metrics of Environmental Performance Performance Category Metric Scope Further Development Activities Energy and Greenhouse Gas (GHG) Emissions Operating energy or GHG emissions per passenger-mile Calculated for new project Include energy/GHG from fuel production as well as direct vehicle operations • Decide whether to use energy, GHG, or both • Develop standard energy and emission factors or guidance for developing project-specific factors Construction energy or GHG emissions Calculated for new project • Research required to develop models for nonmaterials construction energy and GHG • Consider normalizing (per passenger-mile or route-mile) if used for comparing projects Air Quality and Public Health Change in total project emissions Calculated for highway and transit • Determine pollutants of interest • Develop standard g/mi emission factors • Consider combined weighted index of all pollutants • Determine whether and how to include emissions from electricity generation Project air pollutant emissions per passenger-mile a Calculated for transit project only Change in daily nonmotorized access trips Calculated for new project versus no-project • Validation of consistency of results among projects/models • Consider/test total nonmotorized trips accessing new project as alternative Ecology, Habitat, and Water Quality Fraction of corridor land that already is developed Project corridor (x-mile radius) • Consider categorical rating system (e.g., high, medium, low) based on quantitative benchmarks a This alternative air quality metric was considered too late in the process to fully test and compare it to other metrics. While the project team feels that project emissions per passenger-mile may be preferable to change in total emissions for informing comparative project evaluation, it will need to be more fully tested before a final judgment is made. Pros. The pros of this measure are largely similar to the pros of BTU per passenger-mile. This measure has an added benefit of relating directly to a particular environmental impact (GHG emissions) and considering the GHG intensity of different fuel types. Cons. Cons are also largely similar to BTU per passenger-mile. The benefit of introducing GHG as a measure must be weighed against the challenges of fairly assessing differences in the GHG intensity of the same type of fuel among project sponsors-e.g., electricity generation by region of the country; as well as accounting for uncertainty in GHG intensity forecasts and current and future life-cycle GHGs associated with biofuels. Summary. This metric should be considered as an alternative or supplement to BTU per passenger-mile. The transparency of this metric, limitations on uncertainty, and ability to distinguish among projects in a way that is clearly related to environmental impacts make this a promising metric. If the metric were adopted for comparing projects in different regions of the country, attention would need to be given to developing consistent and appropriate energy consumption factors for different types of transit vehicles as well as appropriate life-cycle GHG emission factors (current and future) for alternative fuels. A decision would also need to be made as to whether to use average national GHG intensity factors for electricity generation or regionally specific factors, which would reward projects in regions of the country with a "clean" electricity mix. Metric IE(i)-Construction GHG Emissions Calculation. This metric includes emissions from materials and equipment used in construction of the transit project. Due to data limitations, it was not fully tested on the pilot projects. The metric could be reported in total or normalized per route-mile, per passenger-mile, or per dollar of project cost. It could also be annualized and combined with operating emissions for a life-cycle GHG metric.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1985. Supe... more Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1985. Supervised by James A. Fay. Includes bibliographies.

The Commonwealth of Massachusetts promulgated an Act limiting S2 emissions from large sources tha... more The Commonwealth of Massachusetts promulgated an Act limiting S2 emissions from large sources that burn fuel at a rate greater than or equal to 100 million Btu (MBtu) of fuel input per hour. The Act requires that by 1995 the average emission rate at such facilities be less than or equal to 1.2 lb SO2 per MBtu fuel input. Because of their size, almost all power plants in Massachusetts could be subject to emission reductions. Since the average 1980-1982 annual emission rate of Massachusetts power plants was 1.84 lb S02/MBtu ("base case"), the Act requires the annual average emission rate of power plants to diminish by 35%. We use a source apportionment model to estimate the wet sulfate deposition to typical sensitive Massachusetts receptors from Massachusetts power plants, separately for the summer (April-September) and winter (October-March) half-years. We find that the summer wet deposition is about twice the winter deposition, although summer and winter SO2 emissions are ...

Risk assessors frequently use air dispersion models to estimate exposure point concentrations in ... more Risk assessors frequently use air dispersion models to estimate exposure point concentrations in assessing potential risks to human health and the environment. Most typically, models are used to predict ambient concentrations of contaminants emitted from a variety of different sources of concern, and the assessments overlap with air quality assessments required for Clean Air Act (CAA) permitting. For reasons of consistency and facilitating acceptance (both by the public and the regulatory community), risk assessments are often based on the same models used to demonstrate CAA compliance (i.e., the Appendix W models supported by the Office of Air Quality Planning and Standards). The needs of risk assessors, however, sometimes extend beyond CAA compliance requirements for Title V permitting. As examples, risk assessments of combustion source emissions frequently require multi-pathway models to assess contaminant deposition from the atmosphere and subsequent incorporation into terrestri...

19th Annual North American Waste-to-Energy Conference, 2011

Most ash generated by waste-to-energy (WTE) facilities in the U.S. is landfilled. Studies underta... more Most ash generated by waste-to-energy (WTE) facilities in the U.S. is landfilled. Studies undertaken in the late 1980’s and early 1990’s indicated no significant environmental concerns associated with ash landfilling. However, in 2001, policy-makers at the Massachusetts Department of Environmental Protection (MA DEP) became concerned that the “cumulative” impacts of landfills, including ash landfills, might pose a risk to human health. To address this concern, we performed an in-depth assessment of impacts to air quality, and theoretical risks to health, from fugitive emissions associated with an ash landfill. Nine sources of fugitive ash emissions were modeled using methods that coupled detailed information about the site operations, ash properties, and meteorological conditions on an hour-by-hour basis. The results of these assessments, combined with ambient air data collected by others, demonstrated that the impacts from fugitive emissions of the ash were no more than negligible....

Environmental Progress, 1991

... data, physical property and unit operation models, and mathemat-ical algorithms to generate m... more ... data, physical property and unit operation models, and mathemat-ical algorithms to generate material and energy balances based on the ... The flue gas that feeds each process is taken from a 500 MW coal-fired power plant with an assumed overall thermal cycle efficiency ...

Supervised by James A. Fay. Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mech... more Supervised by James A. Fay. Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1989. Includes bibliographical references (v. 2, leaves 269-273).

Current indoor air pollution models typically assume that contaminants are mixed throughout indiv... more Current indoor air pollution models typically assume that contaminants are mixed throughout individual rooms. In general, this assumption is valid only if air movement is sufficient to disperse the pollutant. In the research, algorithms have been developed to model airborne concentrations of hazardous chemicals in large indoor spaces in which pollutants are not uniformly distributed. SIMULINK, a user-friendly software package for simulating dynamic systems, has been applied to simulate indoor air dispersion of contaminants. The modeling approach consists of dividing the indoor space into an interconnected network of rectangular volumes (parallelepipeds). Development and application of volume, exchange, and emission elements are detailed in the body of the report. The element techniques are best applied to problems in which ventilation data are adequate to characterize air flow patterns within the indoor environment.

18th Annual North American Waste-to-Energy Conference, 2010

Until recently, landfills and waste-to-energy (WTE) facilities were the two basic technologies av... more Until recently, landfills and waste-to-energy (WTE) facilities were the two basic technologies available to process residual (post-recycled) municipal solid waste. These technologies have both advantages and drawbacks, and their relative merits have been debated many different ways. Risk assessments of both technologies have been used to examine their potential threats to human health and the environment, and have found both landfills and WTE facilities can be operated in an environmentally acceptable manner. Neither alternative, however, has gained general public acceptance, and planned projects are often controversial. There remains considerable skepticism, for example, that landfill liners will be effective over long periods of time, and a general uneasiness over the safety of waste combustion. The interest in emerging conversion technologies, such as gasification and anaerobic digestion, as an alternative to conventional landfills and WTE facilities is thus understandable. However, there is some concern that the environmental impacts of conversion technologies are not well understood, as no commercial facilities exist in the United States. Development of a risk assessment framework for evaluating conversion technologies will serve two purposes. First, it will ultimately facilitate objective evaluation of potential risks to health and the environment as well as comparative evaluation with respect to traditional landfill and WTE technologies. Second, it will initiate a conceptual model of environmental impacts that will be useful in identifying key emissions and data gaps. Our presentation will set forth an initial risk assessment framework, focusing on the emissions and residuals of conversion technologies, and using available data to characterize and project health risk impacts.

2013 21st Annual North American Waste-to-Energy Conference, 2013

Unexpected and unusual emissions from a large, mass-burn, waste-to-energy facility caused persist... more Unexpected and unusual emissions from a large, mass-burn, waste-to-energy facility caused persistent and elevated opacity readings of the facility’s continuous opacity monitor (COM), and generated a visible pink-purple-tinted plume emanating from the exhaust stack. Non-radioactive iodine associated with medical wastes was determined to be responsible. As iodine is a known respiratory irritant, questions arose regarding potential short-term health risks to nearby residents. The rate of emission of the apparent release was estimated by two different methods, and then compared with facility-specific knowledge of waste composition. First, based on inverse, worst-case air dispersion modeling, the level of iodine emission that would be necessary to cause potential discomfort/mild irritation to people living near the facility was determined. Second, the level of iodine emission that would be necessary to account for elevations of in-stack opacity observed throughout the event was calculate...

Atmospheric Environment (1967), 1989

The trend of annual average sulfate and nitrate ion concentrations in precipitation at 17 station... more The trend of annual average sulfate and nitrate ion concentrations in precipitation at 17 stations in eastern North America over 7 years 1979-1985 is estimated and compared with a modeled trend. The observed concentrations fluctuate from year-to-year about a mean value with a standard deviation of 12.7% on average. The average slope of a linear regression line at the 17 stations is-2.8%a-' for sulfate and-0.4% a-' for nitrate. The modeled trend at these stations, which assumes constant meteorology but a year-to-year varying emission inventory, is-2.4% a-l for sulfate and-0.9% a-l for nitrate.

A Practical Guide to Understanding, Managing, and Reviewing Environmental Risk Assessment Reports, 2001

20th Annual North American Waste-to-Energy Conference, 2012

Odor control is a frequent issue at facilities that process municipal solid waste. Even waste-to-... more Odor control is a frequent issue at facilities that process municipal solid waste. Even waste-to-energy facilities, which are typically operated under “negative pressure,” may be less than 100% effective at preventing the occasional release of odorous emissions. When odors travel off-property to nearby residents and businesses, the tangible exposure often elicits concerns about the specific chemicals responsible for the odor and the potential for the emissions to affect public health. However, because the gaseous compounds that may lead to objectionable off-site odors are generally different than those that might result in adverse health effects, conditions of odor and risk are not as closely linked as is sometimes assumed. While odors can be assessed through personal observations, the assessment of risk requires detailed knowledge of the composition of the emitted gases. The gas produced from the aerobic decay of municipal solid waste contains a different mix of chemicals that are ...

Atmospheric Environment (1967), 1985

Many field and laboratory experiments on the dispersion of isothermal dense gas clouds use initia... more Many field and laboratory experiments on the dispersion of isothermal dense gas clouds use initial cloud shapes having nearly equal vertical and horizontal dimensions, termed initially compact clouds. The earliest stage of mixing, dominated by the initial spreading motion of the cloud, is modeled in this paper as one having a constant global entrainment rate, the empirical value of which is obtained from comparisons with dense gas cloud releases in still air. By adding to this initial entrainment that due to wind turbulence (as modified by cloud stratification), a good correlation is found for dispersion in wind tunnel tests of initially compact dense gas clouds. This initial high rate of entrainment was found to be missinp in wind tunnel experiments using non-compact clouds. Although no quantitative criterion is available to distinguish among these initial shapes, their effects are eventually erased by the wind driven mixing.