Journal of Environmental Engineering

A pilot air-quality monitoring study was conducted at two locations in San Jose, Calif., between 12/16/91 and 2/24/92, with daytime (0600 to 1800 PST) and nighttime (1800 to next day 0600 PST) PM ₁₀ (particulate matter with an aerodynamic diameter less than or equal to 10 μm) samples. Source profiles (the fractional chemical composition of emissions) from local paved road dust were combined with source profiles from other studies for input to the Chemical Mass Balance (CMB) receptor model to apportion the measured PM ₁₀ to sources and to determine the additional information needed to develop emission-reduction strategies. Residential wood combustion was the largest contributor during this period, especially to nighttime samples, and averaged approximately 45% of the PM ₁₀ mass. Other significant sources included primary motor vehicle exhaust, resuspended road dust, and secondary ammonium nitrate, each contributing between 15% and 20% of the average wintertime PM ₁₀ . Secondary ammonium sulfate and primary marine aerosol contributions were detectable, but these contributed less than 5% to the average PM ₁₀ .

Although awareness of the habitat value of large woody debris in streams has promoted a more environmentally sensitive approach to its management, present guidelines are largely intuitive and do not contain advice for conducting quantitative hydraulic investigations. This review of the literature provides information to assist management, and highlights deficiencies in current knowledge. Hydraulically, debris act as large roughness elements that provide a varied flow environment, reduce average velocity, and locally elevate the water-surface profile. This can significantly increase flood travel time. The significance of debris is scale-dependent. For example, the hydraulic effects are often drowned out in a large flood on a large river. Some hydraulic models can be used to predict the effect of debris removal or reinstatement. A challenge for research is the development of a hydraulically and biologically meaningful definition of debris geometry that can be readily used in the field. When more is known about the physical and biological significance of debris in rivers, a detailed cost-benefit analysis on its management should be undertaken.

As an early component of a comprehensive program to reduce pollution in Boston Harbor, two 80-yr-old cast-iron outfalls, each 1.5 m (60 in.) in diameter and about 1.6 km (1 mile) long, were cleaned in a pigging operation. The operation restored the hydraulic capacity of these pipelines to about 175% of the prepigging capacity. Of particular concern were preserving the integrity of very old and possibly fragile pipe, and minimizing the environmental impact of the cleaning operation, with its discharge of scourings to the marine environment. The planning, monitoring, and execution of the project are described in detail. On each of the two lines, a dye test was conducted to confirm that there were no ruptures in the line. Then the diffuser dome at the downstream end was removed, and the sewage effluent was diverted to the outer outfall. A series of flexible pigs was inserted at the upstream end and driven through the pipe one at a time by a pump-supplied pressure. The progressive improvement in hydraulic capacity is plotted against the progressive number of pig passes made. The planning, monitoring, and execution of the project are described in detail.

The lack of federal guidelines covering disposal of nonhazardous industrial waste (NHIW) has resulted in highly variable and inconsistent state programs for regulating this largest portion of the nation's solid-waste stream. Most states do not have regulations specifically addressing NHIW; the result being a growing backlog of disposal requests that have to be considered on a case-by-case basis, wasting time and money. NHIW poses potential threats to human health and the environment if disposed of as a solid waste; NHIW unnecessarily disposed of as hazardous wastes requires excessive monetary resources. Because of the large quantity of NHIW currently being generated and improperly classified and disposed, this study was directed at developing a comprehensive and usable method for characterizing NHIW. The classification scheme described herein is designed to characterize NHIW based on realistically available information. However, some considerations within the scheme may require NHIW generators to provide realistically obtainable information beyond current requirements.

This laboratory investigation evaluated candidate permeable-barrier media designed to remove benzene from in-situ ground water. There are many obvious potential permeable-barrier media, such as granular-activated carbon or ion-exchange resins; however, these are prohibitively expensive for most potential barrier applications. Therefore, developing low cost, yet effective, barrier materials would expand the breadth of potential applications. This investigation considered the effectiveness of several common materials including coal, powder-activated carbon (PAC), peat, sawdust, and zeolite. These materials were mixed with silica sand, then used in a bottle point isotherm procedure. The PAC and sand mixture was selected as the media for a column investigation, based on the results of batch sample investigations. The evaluation of this mixture in the column investigation showed that batch study efficiency projections were exceeded by 37%. Possible reasons for that finding are proposed. Eventually, these data will be used to design field barriers.

The gas-slippage phenomenon of gas permeability, commonly known as the Klinkenberg effect, has been neglected in the analysis of gas flow. In this work, an exact analytical solution to the gas flow in a two-dimensional axisymmetric-flow domain with anisotropic gas permeability that includes the Klinkenberg effect is presented. The solution is also extended to provide an analytical expression for the stream function. The results suggest that the Klinkenberg effect is important with low-permeable materials such as clay and silt. The errors involved in neglecting the Klinkenberg effect are highest at the well and are reduced with the radial distance.