Evaluation of Volatilization of Hazardous Constituents at Hazardous Waste Land Treatment Sites

The magnitude and extent of volatile organic emissions from hazardous waste land treatment systems were evaluated in laboratory and field studies using complex petroleum refining hazardous wastes. Laboratory experiments were conducted using two soils and a intert construction sand to investigate the emission flux rates of seven volatile constituents, i.e., benzene, toluene, ethylbenzene, p-, m-, o-xylene, and naphthalene, from API Separatory Sludge and Slop Oil Emulsion Solids wastes in column and flask laboratory units as a function of waste application rate, application method (surface versus subsurface), soil type and soil physical characteristics. Field experiemtns were conducted at an active petroleum refinery hazardous waste land treatment site to which a combined API Separator Sludge/DAF bottom sludge was surface applied. The emission rates of the sevel pure volatile constituents evaluated in the laboratory studies were quantified in the field study. Pure constituent collection and quantification in both laboratory and field studies were carried out using a surface isolation emission flux chamber and a split stream Tenax sorbent tube concentration system. Laboratory and field sampling train evaluation indicated that the system is best quited for high emission rate measurements, i.e., just following waste application, and requires diligent QA/QC procedures to minimize background contamination and to assure representativeness of measured data. Suggested operating procedures in terms of purge flow rates, split stream sampling rates, sample collection volumes for minimal contaminant sorbent tube breakthrough, etc., are presented. Measured laboratory and field data were comapred to the Thibodeaux-Hwang Air Emission Release Rate (AERR) model in an effort to validata this state-of-the-art land treatment air emission model. Data generally confirm the validity of the diffusion based on modeling approach for land treatment air emissions, especially for emission rates immediately following sruface waste application. Both field and laboratory surface application measured data correlated with Thibodeaux-Hwang AERR model predictions within a factor of two to ten. Laboratory subsurface application experiments were within one to two orders of magnitude of predicted values. The dynamics of the geometry of the subsurface contaminated zone following subsurface application, along with the hypothesis of concentration gradient development in the soil zone above the application plane, indicate that the simple diffusion based model does not adequately describe the unsteady-state diffusion process occurring following subsurface application events. The variability observed in point waste loading, and soil physical and temperature conditions observed during the field study suggest that detailed waste loading data (using a pan method described in the report) and site and time specific soil data are required for accurate correlations between measured and predicted waste constituent emission flux rates. Once specific data are collected which describe the physical environment of the land treatment system, the accurate prediction of pure constituent air emissions from surface application and tilling can be provided by the Thibodeaux-Hwang AERR model even for complex hazardous wastes applied to complex soil systems. This report was submitted in partial fulfillment of Cooperative Agreement CR-810999-01-0 by the Utah Water Research Laboratory, Utah State University under the partial sponsorship of the U.S. Environmental Protection Agency. This report covers a period from August 1983 to january 1986, and the work was completed as of July 1986