Implications of MTBE for Intrinsic Remediation of Underground Fuel Tank Sites

MTBE in groundwater has been shown to travel over 1,000 feet downgradient from its source in several comprehensive field studies conducted across North America. The biodegradability of MTBE is examined by summarizing all the significant literature on the subject and by detailing the findings of recent field investigations of MTBE transport. In Orange County, California, the persistence of MTBE is analyzed and statistical representations of source variability are presented. Regional and far field transport of MTBE in groundwater sourced from underground gasoline storage tanks are summarized in comprehensive tables of frequency and plume length. Estimates of source mass and duration allow for comparison of associated plume size. The conclusion reached after reviewing all the available literature on MTBE is that its biodegradability seems slight and the size of the plumes are surprisingly large. Intrinsic or natural attenuation remedies for MTBE merit close scrutiny.     

Welcome

Abstract

An indicator of solid waste generation potential (SWGP) is proposed as a versatile means to assist the development of integrated solid waste (SW) management plans. The proposed indicator is based on key sodoeconomic variables for the State of Illinois which were found to be highly correlated with variables describing the SW stream of the State. The proposed indicator was derived by applying the principal components analysis (PCA) technique. The technique is used to merge the rank transformed socioeconomic variables into a single variable, the SWGP indicator, while maintaining the regional information of the original variables. An innovative aspect of this indicator approach is the use of the ordinal scale for all these diverse variables. The validity of this approach was assessed and the proposed indicator was found to be directly proportional to a composite variable describing the SW stream for the State of Illinois. The use of Geographic Information Systems (GIS) to depict the spatial distribution of the SWGP will help planners visualize the expected overall refuse generation pattern and to identify critical regions. In addition, the proposed indicator could be used as an instrument to validate the solid waste generation (SWG) quantities reported by counties to state agencies.     

ESP Bus Section Failures: Design Considerations

This paper addresses a common operation and maintenance problem encountered with sectionalized electrostatic precipitators—bus section failure. ESPs are normally designed to meet a specific minimum collection efficiency in order to comply with emission standards; the loss of several bus sections may cause the unit to be out of compliance. In this paper, the effect of bus section failure on precipitator performance is analyzed. The study is presented in two parts. First, a simplified procedure to estimate the effect of bus section failure on the overall collection efficiency is developed. An illustrative example is presented to demonstrate the use of the technique. Secondly—and this is the main thrust of this study—the technique is extended to include calculations on whether a unit is out of compliance due to the failure of a given number of bus sections. This development clearly shows that this latter effect can only be expressed in terms of a probability. Two additional examples, based on a field unit using actual test data, complement the presentation and illustrate this probability calculation.     

Biodegradability of Quaternized, Crosslinked Sugarcane Bagasse

Quaternized, crosslinked sugarcane bagasse can adsorb anionic dyes from textile wastewater. Disposal of dye-saturated adsorbent by composting or land application would require that modifications made to the bagasse do not interfere with its decomposition. The impact of quaternization and crosslinking on bagasse biodegradability was examined. Bagasse in varying states of modification was mixed with soil and monitored for carbon dioxide evolution for four weeks at 27°C. After subtracting the amount of carbon evolved from control soil samples, the net carbon evolved from the bagasse samples was determined and used as a measure of their extent of biodegradation. Biodegradability decreased in the order: bagasse (approx. 60% degraded after four weeks) > quaternized bagasse > quaternized, epichlorohydrin-crosslinked bagasse > quaternized, methylene-bis-acrylamide-crosslinked bagasse > epichlorohydrin-crosslinked bagasse (less than 5% degraded). Crosslinking severely impacted biodegration, probably by preventing the penetration of (hemi)cellulytic and lignolytic enzymes into the interior of the modified bagasse particles. It is concluded that the biodegradability of quaternized, crosslinked bagasse is too low for composting or land application.     

Hydrograph Separation by Incorporating Climatological Factors: Application to Small Experimental Watersheds 1

Abstract: Evaluating the relative amounts of water moving through the different components of the hydrological cycle is required for precise management and planning of water resources. An important aspect of this evaluation is the partitioning of streamflow into surface (quick flow) and base‐flow components. A prior study evaluated 40 different approaches for hydrograph‐partitioning on a field scale watershed in the Coastal Plain of the Southeastern United States and concluded that the Boughton’s method produced the most consistent and accurate results. However, its accuracy depends upon the proper estimation of: (1) the end of surface runoff, and (2) the fraction factor (α) that is function of many physical and hydrologic characteristics of a watershed. Proper identification of the end of surface runoff was accomplished by using a second derivative approach. Applying this approach to 12 years of separately measured surface and subsurface flow data from a field scale watershed (study area) proved to be accurate for 87% of the time. Estimation of the α value was accomplished in this study using two steps: (1) alpha was fitted to individual hydrographs: and, (2) a regression equation that determines these alpha values based on climatological factors (e.g., rainfall, evapotranspiration) was developed. Using these strategies improved the streamflow partitioning method’s performance significantly.     

Policy And Practice Green Grass and Brown Roots: Understanding Environmental Problems in Deprived Neighbourhoods

Understanding neighbourhood conditions can play an important role in urban environmental management, especially when environmental services are lacking and new approachesare being debated. This paper describes and evaluates three research methods for assessing some of the environmentalproblems facing low income households and communities: (1) broad spectrum household surveys; (2) participatory rapid assessment; and (3) contingent valuation. As part of the study upon which this paper is based, the techniques were applied on a small scale in Jakarta. The paper finds that each technique can provide important and often complementaryinsights. The broad spectrum survey is particularly suitable to broad based planning, participatory appraisal to NGO initiatives and contingent valuation to utility pricing decisions.