Air infiltration measurements in a home using a convenient perfluorocarbon tracer technique

Using miniature perfluorocarbon tracer (PFT) sources and miniature passive samplers, both about the size of a cigarette, tests conducted in the laboratory and in a typical home successfully demonstrated the utility of the PFT kit as a means for implementing wide-scale infiltration measurements in homes. The PFT diffusion plug source, an elastomer containing a dissolved perfluorocarbon compound, was shown to emit vapors at the rate of about 0.1 to 5 nL/min, providing steady-state concentrations in a home of about 1 to 10 pL/L, i.e., parts per trillion by volume, when one source is deployed for each 300–500 ft² (28–46 m²) of living space. The emission rate from the diffusion source was predictable, but its dependence on both temperature and time suggested the development of alternative approaches. One such alternative, a liquid PFT permeation source, had emission rates which could be tailored over the range 10–20 nL/min, were independent of age for as long as the liquid remained ( 5 yr), and had significantly lower temperature dependence. A number of passive adsorption tube samplers performed reproducibly and identically (to within ±2%–3%) in laboratory tests. Together with a programmable tracer sampler, the miniature diffusion sources and samplers were deployed in a typical home; six PFT sources were uniformly deployed, three on each level of a two-story house. Multiple location sampling, as well as sampling in rooms with and without a miniature source, demonstrated that even in a house without forced-air circulation, a well-mixed modeling approach is justified. Analyses of the tracer samplers were performed back in the laboratory with an automatic electron-capture gas-chromatography system. The effects of the inside/outside temperature differential, as well as that of an open fireplace compared with a wood-burning stove, on the measured air infiltration rates were clearly demonstrated. Comparisons of the PFT tracer method with that of the SF₆ tracer decay approach showed the results of the two methods to be identical within experimental precision. With this miniature source and sampling tracer kit, infiltration rates in the range 0.2–5 air changes per hour can be measured over time-averaged periods of as little as 1 day up to several years.     

COMPUTATION OF RUNOFF REDUCTION CAUSED BY FARM PONDS1

ABSTRACT: A two-parameter farm pond storage index, FPSI, was Used to adjust computed surface. runoff using the partial area runoff contribution resulting from runoff captured by farm ponds. The validity of the index method was tested by fitting a continuous accounting version of the Soil Conservation Service curve number procedure to surface runoff data from each of three watersheds, first with and then without the FPSI routine. Evapotranspiration computed with the Jensen-Haise method and rainfall were input to the model. A linear relationship was assumed between the storage index and the portion of the controlled drainage area that was contributing to runoff. Adjusting the computed runoff with the FPSI reduced the coefficient of variation of monthly measured versus computed surface runoff for each of the three watersheds. The correlation coefficients for the same comparisons were increased. The annual predicted surface runoff Was improved for 12 of the 17 station years of data tested. The farm pond storage index could be used with any surface runoff model to improve the prediction of runoff from watersheds with drainage areas greater than 1 square mile and with about 20 percent or more of the drainage area controlled by farm ponds.     

DATA REQUIREMENTS OF A WATER QUALITY MANAGEMENT PROGRAM1

ABSTRACT: Routine data collection currently consumes a large amount of the total resources devoted to water quality management. All too often data collection becomes an end in itself, with little thought given to the purpose of the data collection. The problem generally stems from a lack of proper routine surveillance system design and a failure on the part of the designers to initially identify the data needs of the management program. This study attempts, in a general way, to delineate the data needs of a water quality management program. This first required an identification of the activities involved in water quality management. The activities were then discussed in terms of the types of information needed to successfully complete their assigned tasks. Several detailed examples are given. The results of the discussion are summarized and several strategies are proposed to relate the results to surveillance system design.     

Private micro-hydro power and associated investments in Nepal: the Barpak village case and broader issues

This article examines a number of issues connected with the development of small-scale hydroelectric power and related investments in Nepal. The micro-hydro investment scheme in Barpak village serves as a case study, and the article also presents a number of related issues discussed against the background of the evolution of micro-hydro power in Nepal. The article outlines the success of micro-hydro development, modest in relation to its enormous potential, the realization of which depends on whether a number of challenges and constraints can be overcome. The article closes with suggestions on implementing sustainable micro-hydro development in rural areas, based on the Barpak experience and the authors' other recent studies of rural energy issues in Nepal.     

Dispositional affectivity as a predictor of work attitudes and job performance

Previous research has shown that dispositional negative affect (NA) is associated with lower levels of job satisfaction. Little research has been conducted, however, on other organizational implications of negative affect or on the potential effects of dispositional positive affect (PA). The present studies examined the relationship of both positive and negative affectivity to organizational commitment, turnover intentions, global job satisfaction and performance. In the first study both NA and PA were associated with organizational commitment and turnover intentions. Additionally, commitment mediated the relationship between dispositional affectivity and turnover. Finally, PA and tenure interacted to predict job performance, such that PA and job performance were positively related, but only for high tenure employees. In Study 2 the findings were generally similar, but not identical. Both NA and PA were related to global job satisfaction and turnover intentions. However, only PA was related to affective organizational commitment. Moreover, both job satisfaction and affective commitment mediated the relationship between dispositional affectivity and turnover intentions. Finally, unlike Study 1, PA was not related to job performance. Rather, NA and tenure interacted such that when individuals were lower in tenure, NA was negatively related to performance.     

RCRA corrective action costs: An estimating model for nonfederal facilities

This article presents an analysis of the prospective costs of RCRA corrective action for private, nonfederal facilities. Two data bases developed by Research Triangle Institute and a remedial action cost model developed by CH2M Hill provide the foundation for this work. The methodology has two components, a remedial action knowledge base and a discrete-state Monte Carlo analysis. Under base case assumptions, it is estimated that the total costs of RCRA corrective action will be $240 billion, with a 5 percent chance the costs will be less than $170 billion and a 5 percent chance the costs will be more than $377 billion.     

Environmental cost accounting: The bottom line for environmental quality management

Recent years have seen the environment emerge as one of the most pressing issues facing American business. Eventually, environmental costs will affect the bottom line of every American company. A recent study in the National Law Journal estimates that cleanup of the nation's known hazardous wastes sites will cost $752 billion over thirty years under current environmental policies. Environmental legislation and regulations impose annual compliance costs estimated by the Environmental Protection Agency at more than $30 billion. In the near future, environmental expenses for cleanup, regulatory compliance, and management are anticipated to grow to between 2.5 and 3 percent of GNP. Corporations that wish to be competitive must successfully manage these costs while maintaining or improving their role as responsible corporate citizens. Implementing a comprehensive system for identifying and managing environmental costs requires a multidisciplinary team effort. Environmental costs impact product selection, design and pricing, capital budgeting, and future strategic direction. In order to make informed and meaningful managerial decisions on environmental programs, real cost data are vital. An environmental management systems (EMS) requires information to set goals and then monitor progress towards those goals over time. This article will discuss the current cost accounting systems (CASs) available to support the myriad goals of environmental management systems. In addition, the article will outline a framework for plotting the location of your current EMS on a matrix of regulatory and information requirements and evaluating whether your corporation's CAS is adequate to support the goals and objectives set by your environmental management program. By anticipating future regulatory and information requirements, flexible systems can be developed to adapt to new and more stringent regulations and more complex information requirements.     

DESIGNATION OF WETLANDS BY WEIGHTED AVERAGES OF VEGETATION DATA: A PRELIMINARY EVALUATION1

ABSTRACT: Weighted averages (WA) was investigated as a vegetation-based method for wetland designation, to be used in conjunction with the wetland indicator status of plants from Wetland Plants of the United States of America 1986 (Reed, 1986). Ecological indices were assigned to indicator groups and were used to compute weighted averages for quantitative data obtained from four studies of wetland vegetation conducted in various regions of the United States. Weighted averages of vegetation data proved to be a useful tool for assessing wetland status of the vegetation types included in our study: (1) rankings of vegetation stands or types by WA correlated well with their positions on environmental moisture gradients; and (2) the results of WA could be used, together with a wetland/upland break-point, to designate vegetation types as wetland or upland in a way that agreed well, in three of the four studies, with an alternative classification of wetland habitats. The variation of weighted averages among the sampling units representing a vegetation type was generally small relative to the range of ecological indices assigned. However, designations based on weighted average scores close to the break-point should be considered provisional and must be verified with supplementary data on soils and hydrology.     

HYDROLOGY OF A SMALL IMPOUNDMENT AND WATERSHED IN CENTRAL OKLAHOMA1

ABSTRACT: West Bitter Creek floodwater retarding structure site 3 in South Central Oklahoma was instrumented and records obtained and analyzed to obtain information concerning an impoundment water budget that is useful to landowners and designers of these impoundments. On-site loss of water from the impoundment was only 17 percent of the inflow during three years when the annual precipitation averaged 26 inches and the annual inflow averaged 1.4 inches. Runoff from an eroded area with no farm ponds was about 70 percent greater per unit area than from a portion of the watershed where 71 percent of the drainage area was controlled by farm ponds. A previous study indicated, however, that the ponds were reducing runoff only 13 percent. Loss of top soil increases runoff considerably. Only 24 percent of the total runoff into the impoundment was base flow. The flow rate into the impoundment was less than 0.05 cfs 70 percent of the time, and the inflow rate exceeded 10 cfs only 1 percent of the time. SCS runoff curve numbers varied between 57 and 96 for the impoundment watershed with an inverse relation between precipitation amount and curve number apprently caused by partial area runoff from impervious and semi-impervious areas. A comparison of measured event runoff versus event runoff computed by the SCS curve numbers gave an r² of only 0.44. However, the total computed surface runoff for eight years of record was less than 1 percent below the measured runoff which indicated the curve number method was a good tool for predicting long term runoff for the watershed.