The Versatility of Organoclays for Permeable Barriers

George Alther, Biomin, Inc., P. O. Box 20028, Ferndale, MI 48220, Tel: 248-544-2552, Fax: 248-544-3733

Permeable barriers at creosote and PNAH containing sediments, require a barrier, which is permeable, and, at the same time, traps creosote and PNAH  plumes.  Such plumes can also include such organic hydrocarbons as PCP and other chlorinated phenolic compounds, PCB’s and BTEX’s.  Lab tests and actual field applications have shown that organically modified clays are an excellent medium to trap such compounds in groundwater and in sediments at old MPG sites.

The PNAH compounds include naphthalene, pyrene, fluorine, anthrazene and others. Organoclays are very well suited to trap these compounds efficiently. Since pesticides are also a serious problem for groundwater and sediments, a brief literature review is included.

This article reports on various laboratory tests and actual field results, which have been obtained over the years, showing the suitability of organoclays as a component of permeable barriers.

Remediation of a Clay Contaminated with Petroleum Hydrocarbons using Soil Reagent Mixing

Vito Schifano, Arcadis Geraghty and Miller International Ltd, Newmarket, CB8 7FA, UK, Tel 0044 (0) 1638 674781, Fax 0044 (0) 1638 668191, Email: vschifano@arcadisgmi.com

Soil reagent mixing (SRM) is an in-situ remediation technique whereby powder or slurried reagents are delivered and mixed to contaminated soils or sediments by augers or other types of soil mixers.  This paper summarises the work carried out for a laboratory treatability study of SRM on soil samples contaminated with petroleum hydrocarbon compounds from a petrol filling station site in Kent, UK. The studies examined the effects of mixing several binder reagents on the concentrations and leachability of the hydrocarbons. Quicklime, Hydrated Lime, Ordinary Portland Cement in a number of different formulations were used in the study. Furthermore, the addition of Gypsum to some reagent formulations was evaluated in an attempt to improve the strength of the binder/soil mix. After mixing the soils with the reagents, pH, temperature, moisture content, Atterberg limits, Total Organic Carbon (TOC) and concentrations of petroleum hydrocarbon compounds were determined on soil and leachate samples extracted from the treated soils. Significant decreases in concentrations of petroleum hydrocarbon compounds were measured in soils and leachates upon mixing of the reagents. The mechanisms responsible for these decreases were examined. The effects of the addition of binders on the Atterberg limits and unconfined compressive strength of the samples were determined. Significant increases in the remolded strength of the clay were observed upon addition of certain binders.

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