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Disposal of Granular Solid Wastes In The Western Canadian Sedimentary Basin By Slurry Fracture Injection

Dusseault , M . B ., Bilak , R . A ., Bruno , M . S . and Rothenburg , L ., Paper presented at the International Symposium of Scientific and Engineering Aspects of Deep Injection Disposal of Hazardous and Industrial Wastes , Berkeley, CA, May 10-13, 1994 (published 1995).

Abstract

Introduction

Injection of a water/solids slurry into permeable, porous strata at depth using oil-field hydraulic fracturing technology is a viable approach to permanent disposal of large-volume, solid, inert terminal waste streams, and is likely to be of interest for other more toxic solid wastes as well. The Western Canadian Sedimentary Basin, and by extension most other sedimentary basins, essentially has an unlimited number of suitable uses.

Large volumes means that a waste injection well will accept approximately 10 4 -10 5 m 3 of solid waste (volume in situ ) over its life, a volume of injection many times larger than the largest hydraulic fractures used in the oil industry. Slurry injection is intended for inert granular terminal wastes. Inert means no decomposition or gas generation as would occur with large quantities of organic waste, as well as minimal chemical reactivity with strata or other wastes. Inert does not necessarily mean insoluble; halite wastes are soluble, but can be disposed by deep waste injedkm. Granular means that the solid waste can be prepared as a particulate medium to be slurried in a liquid stream for injedhn. Clinker or calcined waste can be ground, plastics shredded. toxic waste pelletized if necessary. Terminal means that portion of the waste remaining after reducing, reusing, recycling, and rehabilitating have been economically implemented. It implies that further attempts to deal with the waste will neither be cost-effective nor environmentally secure.

Toxicity is an issue for regulatory agencies to define, and the definition affects site selection and operational parameters of slurry injection. If a waste is non-toxic but of no commercial value, such as flue gas desulphurization sludge, phosphogypsum, non-reusable plastics or composites, and Solvay process wastes (Davidson et al. 1994), site constraints and injection depth can be modest. Mildly toxic solid wastes, such as co-produced oil field solids, brine-saturated sludge from potash refining, clinker, boflom ash and fly ash, would require more rigorous constraints on injection depth and hydrogeological conditions. Genuinely hazardous materials, such as PCB-contaminated soil, heavy-metal contaminated clays, or mildly radioactive soils such as around the Chernobyl site in Ukraine, would require deep injection under stringent controls into most favorable sites.

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