Treatment of Petroleum-Contaminated Soil In
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United States Department of Agriculture Forest Service Technology & Development Program 7100 Engineering September 2002 0271-2801-MTDC David L. Barnes University of Alaska Fairbanks Shawna R. Laderach University of Alaska Fairbanks Charles Showers Program Leader USDA Forest Service Technology and Development Program Missoula, MT 9E92G49—HazMat Toolkit September 2002 The Forest Service, United States Department of Agriculture (USDA), has developed this information for the guidance of its employees, its contractors, and its cooperating Federal and State agencies, and is not responsible for the interpretation or use of this information by anyone except its own employees. The use of trade, firm, or corporation names in this document is for the information and convenience of the reader, and does not constitute an endorsement by the Department of any product or service to the exclusion of others that may be suitable. 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Contents Introduction __________________________________ 1 Understanding the Problem______________________ 3 Petroleum _______________________________________________ 3 Movement of Petroleum in Unsaturated Soil _____________________ 6 Climatic Conditions ________________________________________ 7 Treatment Options____________________________14 Excavation and Proper Disposal _____________________________ 14 Incineration _____________________________________________ 15 Thermal Desorption _______________________________________ 16 Soil Washing ____________________________________________ 17 Ex Situ Vapor Extraction ___________________________________ 18 Composting _____________________________________________ 19 Landfarming _____________________________________________ 21 Soil Vapor Extraction ______________________________________ 22 Barometric Pumping ______________________________________ 23 Bioventing ______________________________________________ 24 Summary ___________________________________26 References __________________________________27 Appendix A—Soil Restoration Vendors _________________ 28 Appendix B—Remediation Products Summary ___________ 35 Appendix C—Vendors and Consultants Interviewed ______ 56 ii Introduction he number of sites contaminated report addresses the Tongass and Chu- the appropriate treatment technology (or with hazardous compounds in gach National Forests in Alaska (figures technologies) is a challenge that requires TTrecent years has prompted environ- 1 and 2). These forests are in cold regions knowledge of the science involved and mental engineers to develop new technol- with temperatures dropping as low as some professional judgment. This report ogies and to adapt existing technologies about –2 °C during winter (Valdez wea- is not meant to provide a “cookbook” to treat contaminated groundwater and ther station, data from Alaska Climate method of selecting a technology for soil. Environmental engineers already Research Center, University of Alaska treating contaminated soils. knew how to treat domestic wastewater Fairbanks). They are also wet, receiving and industrial wastewater. Because they more than 500 centimeters of rainfall Because of uncertainties in soil properties, had some control over these processes, annually (Whittier weather station, data the total mass of contaminant released, engineers had a fairly good understanding from Alaska Climate Research Center, the lateral and vertical extent of contami- of the characteristics of the wastes and University of Alaska Fairbanks). Access nation, seasonal fluctuations in the water the technologies that would work best to and utility accessibility are key issues for table, and weather conditions, it is very treat them. Environmental engineers are engineers in these remote national forests. difficult to predict the outcome of a soil now faced with treating soil and ground- treatment technology (Massmann, J.; water contaminated with petroleum This report will provide Forest Service Schock, S.; Johannesen, L. 2000; Barnes products. Engineers usually have less engineers some guidance to help them and McWhorter 2000). The goal of the knowledge of the characteristics of this choose a treatment technology that will design engineer is to choose and design waste. Adding to the new challenges, reduce the level of petroleum contami- the most economical treatment system contaminants in soil and groundwater nation in contaminated soils. Selecting (a treatment system can be made up of are dispersed throughout the media; in other words, the contaminants are not contained as an industrial or domestic waste would be. Environmental engineers have adapted proven technologies and have developed new technologies to reduce contaminants in soil and groundwater ex situ (removed from the original location) and in situ (in place). Ex situ treatment methods incor- porate both chemical and biological pro- cesses. Over the years, experience has shown that ex situ treatment processes can be costly in capital, operations, and maintenance. In situ methods attempt to stabilize or reduce the mass of contam- inants in soil and groundwater using physical, chemical, and biological pro- cesses. In most cases, these treatment methods are more difficult to control than ex situ methods. The complexity of these treatment methods can be attributed to heterogeneities in soil properties. Soil and groundwater contamination is not limited to industrial or urban locations. Contamination can be found in rural and even in remote locations. The U. S. De- partment of Agriculture, Forest Service is now addressing small-volume (less than 400 cubic meters) soil contamination by petroleum products in remote national forest locations where climate, utility access, and accessibility present chal- Figure 1—Approximate boundaries of the Tongass National Forest. Boundaries are shown as lenges to economical restoration. This dotted lines. 1 Introduction such as incineration of contaminated soil, will vary depending on the vendor. Finally, the authors assume that Forest Service engineers have the best infor- mation on costs for such items as labor and equipment rental. Before engineers address any waste treat- ment issue, they must have an under- standing of the waste to be treated and, in the case of contaminated soil, the medium in which the waste exists. This report will provide a brief description of petroleum products and a simple concep- tual model of the movement of petroleum through unsaturated soil. It includes brief descriptions of the climatic conditions in the Tongass and Chugach National For- ests. The report also describes each viable treatment technology and discusses its applicability for treating contaminated soil in the Tongass and Chugach National Forests. Treatment technologies addressed in this report are shown in table 1. Table 1—Viable treatment technologies for petroleum-contaminated soils. Figure 2—Approximate boundaries of the Chugach National Forest. Boundaries are shown as Ex situ treatment technologies dotted lines. Excavation and proper disposal Incineration more than one technology) that has a manuscript is not a primer on this design Thermal desorption high probability of attaining the intended approach, the manuscript was written Soil washing goal. Because of the uncertainties listed with this approach in mind. Vapor extraction above, the design engineer may have Composting difficulty achieving the stated goal. For This report discusses several technolo- Landfarming example, if the engineer specifies the use gies that are known to be successful for of landfarming to treat contaminated soil, treating petroleum-contaminated soils in an unseasonably cold summer could in- cold, wet, and remote regions. The docu- hibit the effectiveness of this technique, mented performance of each technology In situ treatment technologies delaying the project’s completion. Design- is a compilation of the experience of dif- ing systems under conditions of uncertain ferent commercial companies and Alaskan Soil vapor extraction variables is not a new problem. Terzaghi engineers specializing in restoration of Barometric pumping (1961) addressed this issue as it applied contaminated soil. Appendix C lists the Bioventing to geotechnical engineering. Others have commercial and engineering companies also investigated this topic (Peck 1969; that provided information for this report. Peck 1980; Dean and Barvenik 1992). The conclusion from decades of working Actual costs for the different technologies on this issue is that “cookbook” design have not been included in this document. Before contaminated soil can be treated, protocols do not work. A method that has Instead, items that need to be included the lateral and vertical extent of the con- been successfully applied in geotechnical in a cost estimate are listed. Including tamination