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Slurry trench construction for pollution migration control
Waste Management & Research (1985) 3, 89-92
REPORTS
AND
REVIEWS
BOOK REVIEW: SLURRY TRENCH CONSTRUCTION FOR POLLUTION CONTROL. By The Municipal Envknmental Research Laboratory. mental Protection Agency, Cincinnati, OH 45268, U.S.A. (1984): EPA 250 pp. Government Printing Office 1984-759-102/846. Reviewed by Harwell, U.K.
MIGRATION U.S. Environ540/2-fI4-001. D. Campbell,
A comprehensive review is presented of current knowledge on the techniques for using various soil or cement-bentonite slurry walls to prevent migration of polluted liquids. The various sections, which contain discussion and data on the technical aspects of slurry wall construction to alleviate identified problems at a site, are set out in the form of a handbook which should assist any major consultancy company involved in this technology. It is not however likely to be of significant benefit to individual site operators or small organizations, who are unlikely to have adequate technical resources to either identify the extent of a problem or assess and then implement the necessary remedial measures as described in each section. At the outset it is acknowledged that the use of slurry trenches may not be suited to all types of site and that certain slurry materials may not be compatible with all waste types. Detailed descriptions and technical data are given on the various types of bentonite, their properties and those of admixtures and bentonites with soils and cements which are used to form the final slurry walls. It is evident from the discussion in several of the sections that a considerable amount of detailed site investigation is required before considering the applicability of slurry walls. Data must be obtained about such factors as the quantities and composition of raw materials, which may be available either on or off the site for use in the slurries; the groundwater pattern in the area and the extent and composition of any migrating polluted liquid. Furthermore, the use of slurry walls is a passive measure and additional controls will be required such as the extraction and subsequent treatment of contaminated liquid from within the site containment which such trenches provide, and diversion and/or depression and surrounding groundwater. Laboratory testing both to ascertain the compatibility of the chosen material with the liquid waste, and to obtain data on the slurry permeability and other physical characteristics, are considered to be essential prerequisites before construction is undertaken. The handbook contains a large number of good clear diagrams, to complement the text and to illustrate how slurry trenches and walls are constructed and can be used at a number of “typical” site locations. There are a number of potential geotechnical problems which may occur after the installation has been completed. Practical methods for monitoring the effectiveness of the installation and identification of some of the more common potential problems which may occur are given. Finally the report gives some detailed unit castings for the various necessary activities associate with slurry-trenching, although inevitably as the report has been commissioned and published as part of the implementation of CERCLA, otherwise known as “Superfund” legislation, in the U.S.A., the costs quoted will require factorising if applied to other countries.
90
Reports
and
reviews
It is undoubtedly a valuable reference document for providing guidance on long-term measures for pollution migration control. However, if all the appropriate recommended procedures were followed, and in particular those relating to the availability and compatibility of slurry materials with polluting liquids and to the gathering of field data, the ability to solve acute problems in the short-term is debatable. Some discussion of the effectiveness of short-term control measures, e.g. immediate removal of leachate and/or depression of surrounding groundwater, and how such measures might be integrated with the longer-term controls as advocated, would have been useful. It is, finally, unclear whether the construction designs required, and hence the integrity of the various systems described, are necessary to achieve various pre-determined environmental water quality standards in the U.S.A. If so, what are these standards and how do they compare with those of other countries where such control measures might be similarly required, but perhaps to achieve either higher or lower water quality standards? BOOK REVIEW: RECYCLING OF SOLID WASTES. By B. N. Lohani, G. Todino and R. Jindal. Environmental Sanitation Reviews, No. 13/14, September 1984. Environmental Sanitation Information Center (ENSIC), Asian Institute of Technology, P.O. Box 2754, Bangkok 10501, Thailand. 140 p. Price not given. Reviewed by R. B. Dean. The scope of this Review is based on the general concept of the term “resource recovery” which refers to any use of what would otherwise be a waste material requiring disposal. The scope is further limited to municipal solid wastes, more specifically urban community wastes arising in large cities and towns. The document presents a summary of technical options available for reclamation of urban solid wastes, emphasizing low cost options of waste recycling suitable for the developing countries. Reclamation of nightsoil and sludge are the subjects of other ENSIC publications and are not covered. One limitation of this report is that the major part of its content reviews the experiences of the developed countries because most of the available literature reported comes from them. Although there are many on-going projects of waste recycling in the developing countries of the region, still there is a lack of organized published reports regarding the findings of these projects. An outline and examination of the key criteria used to determine the viability of recovery alternatives under given conditions is covered. Whenever possible, the cost/benefit data of existing operations, as well as the socioeconomic considerations involved in the choice of the reclamation process, have been quoted. Over 150 references are cited. Although the general approach of this review of solid waste recycling covers familiar ground, the many examples from developing countries and their differences from the Western World are illuminating. A table of waste production shows values from a low of 90 kg per person per year in Katmandu and Rangoon to a high of 400 kg per person per year in the City of Luxemburg. Singapore, however, at 320 kg per person per year is above all other European and U.S. examples given. The difference is clearly in terms of the stage of development and not the geographical region. At attempt has been made to list all reported processes for recycling with the result that undue emphasis is given to a large number that received promising preliminary reports (by their sponsors) but which were not successful and have not been heard from since. Some lists of new processes are over five years old. The section on pyrolysis is particularly bad in this report, a table of nearly 50 plants in the U.S.A. (1981) has no
REPORTS
AND
REVIEWS
BOOK REVIEW: SLURRY TRENCH CONSTRUCTION FOR POLLUTION CONTROL. By The Municipal Envknmental Research Laboratory. mental Protection Agency, Cincinnati, OH 45268, U.S.A. (1984): EPA 250 pp. Government Printing Office 1984-759-102/846. Reviewed by Harwell, U.K.
MIGRATION U.S. Environ540/2-fI4-001. D. Campbell,
A comprehensive review is presented of current knowledge on the techniques for using various soil or cement-bentonite slurry walls to prevent migration of polluted liquids. The various sections, which contain discussion and data on the technical aspects of slurry wall construction to alleviate identified problems at a site, are set out in the form of a handbook which should assist any major consultancy company involved in this technology. It is not however likely to be of significant benefit to individual site operators or small organizations, who are unlikely to have adequate technical resources to either identify the extent of a problem or assess and then implement the necessary remedial measures as described in each section. At the outset it is acknowledged that the use of slurry trenches may not be suited to all types of site and that certain slurry materials may not be compatible with all waste types. Detailed descriptions and technical data are given on the various types of bentonite, their properties and those of admixtures and bentonites with soils and cements which are used to form the final slurry walls. It is evident from the discussion in several of the sections that a considerable amount of detailed site investigation is required before considering the applicability of slurry walls. Data must be obtained about such factors as the quantities and composition of raw materials, which may be available either on or off the site for use in the slurries; the groundwater pattern in the area and the extent and composition of any migrating polluted liquid. Furthermore, the use of slurry walls is a passive measure and additional controls will be required such as the extraction and subsequent treatment of contaminated liquid from within the site containment which such trenches provide, and diversion and/or depression and surrounding groundwater. Laboratory testing both to ascertain the compatibility of the chosen material with the liquid waste, and to obtain data on the slurry permeability and other physical characteristics, are considered to be essential prerequisites before construction is undertaken. The handbook contains a large number of good clear diagrams, to complement the text and to illustrate how slurry trenches and walls are constructed and can be used at a number of “typical” site locations. There are a number of potential geotechnical problems which may occur after the installation has been completed. Practical methods for monitoring the effectiveness of the installation and identification of some of the more common potential problems which may occur are given. Finally the report gives some detailed unit castings for the various necessary activities associate with slurry-trenching, although inevitably as the report has been commissioned and published as part of the implementation of CERCLA, otherwise known as “Superfund” legislation, in the U.S.A., the costs quoted will require factorising if applied to other countries.
90
Reports
and
reviews
It is undoubtedly a valuable reference document for providing guidance on long-term measures for pollution migration control. However, if all the appropriate recommended procedures were followed, and in particular those relating to the availability and compatibility of slurry materials with polluting liquids and to the gathering of field data, the ability to solve acute problems in the short-term is debatable. Some discussion of the effectiveness of short-term control measures, e.g. immediate removal of leachate and/or depression of surrounding groundwater, and how such measures might be integrated with the longer-term controls as advocated, would have been useful. It is, finally, unclear whether the construction designs required, and hence the integrity of the various systems described, are necessary to achieve various pre-determined environmental water quality standards in the U.S.A. If so, what are these standards and how do they compare with those of other countries where such control measures might be similarly required, but perhaps to achieve either higher or lower water quality standards? BOOK REVIEW: RECYCLING OF SOLID WASTES. By B. N. Lohani, G. Todino and R. Jindal. Environmental Sanitation Reviews, No. 13/14, September 1984. Environmental Sanitation Information Center (ENSIC), Asian Institute of Technology, P.O. Box 2754, Bangkok 10501, Thailand. 140 p. Price not given. Reviewed by R. B. Dean. The scope of this Review is based on the general concept of the term “resource recovery” which refers to any use of what would otherwise be a waste material requiring disposal. The scope is further limited to municipal solid wastes, more specifically urban community wastes arising in large cities and towns. The document presents a summary of technical options available for reclamation of urban solid wastes, emphasizing low cost options of waste recycling suitable for the developing countries. Reclamation of nightsoil and sludge are the subjects of other ENSIC publications and are not covered. One limitation of this report is that the major part of its content reviews the experiences of the developed countries because most of the available literature reported comes from them. Although there are many on-going projects of waste recycling in the developing countries of the region, still there is a lack of organized published reports regarding the findings of these projects. An outline and examination of the key criteria used to determine the viability of recovery alternatives under given conditions is covered. Whenever possible, the cost/benefit data of existing operations, as well as the socioeconomic considerations involved in the choice of the reclamation process, have been quoted. Over 150 references are cited. Although the general approach of this review of solid waste recycling covers familiar ground, the many examples from developing countries and their differences from the Western World are illuminating. A table of waste production shows values from a low of 90 kg per person per year in Katmandu and Rangoon to a high of 400 kg per person per year in the City of Luxemburg. Singapore, however, at 320 kg per person per year is above all other European and U.S. examples given. The difference is clearly in terms of the stage of development and not the geographical region. At attempt has been made to list all reported processes for recycling with the result that undue emphasis is given to a large number that received promising preliminary reports (by their sponsors) but which were not successful and have not been heard from since. Some lists of new processes are over five years old. The section on pyrolysis is particularly bad in this report, a table of nearly 50 plants in the U.S.A. (1981) has no