Reprinted by ZWA.  All quotes in this section reference more than 30 other research reports and articles. Thanks to Dan Knapp of Urban Ore for extracting these important quotes of the authors' work.

MECHANISMS OF LEAKAGE THROUGH SYNTHETIC LANDFILL LINER MATERIALS 

by S.E. Butler, A.P. Butler, F.M. Johnston, C.J. Sollars, and R. Perry. JCIWEM, 9 AUG 1995, Imperial College, United Kingdom.  

"The results of chemical exposure on flexible membrane liners (FMLs) can range from minor effects such as discolouration to more serious problems such as swelling...In extreme cases the liner may dissolve...or...tearing, cracking, or puncturing {may occur}... the waste may react with the liner-causing degradation of the polymer or its additives or... the waste may dissolve into the liner-resulting in swelling of the membrane without degradation of the polymer." (p.353)

"A small volume of highly contaminating leachate is likely to have as serious an impact as a large volume of less-contaminated material." (p.354)

"Solute migration...is a chemical process occurring on a molecular level, and each constituent of the leachate will be transported at a different rate...Therefore, the composition of leachate produced by hydraulic flow will {be} similar to the contained liquids, whereas the composition of leachates produced by...diffusion will reflect the chemical species which are transported through the liner most rapidly." (p. 354)

"The best evidence for the ...problems with geomembranes is found in the water industry, where contamination of drinking water due to ...permiation of trace organic contaminants from soil through plastic pipes has occurred...A plastic water pipe passing through contaminated soil is a similar situation to that of a landfill liner separating clean soils from contaminated wastes." (p.355)

"Laboratory studies have...also demonstrated the transport of solvents through membranes...Haxo and Labey...demonstrated the transport of trichloroethylene and toluene through a membrane into an underlying chamber containing water...Part and Nibras measured diffusion parameter for a range of volatile organic compounds in HDPE liner materials, and demonstrated that this...might be a significant source of waste release from lined landfill sites." (p.355)

"Factors occurring in a waste containment site which might affect transport rate include temperature, pressure.. and elongation due to tensire stress. As the temperature increases...diffusion..will increase due to greater thermal motion in the polymer chains producng more transient voids into which the waste can migrate." (p.356)

"Diffusive mass transport could have a significant environmental impact by allowing the release of organic solvents though intact membranes at rates comparable, if not larger, with those of leakage through defect. However, in the case of diffusive mass transport there is no likelihood that the rate of leakage will minimized by ...good-quality assurance as it is an inherent property of the material...used." (p.357)

"It is possible that leachate produced by diffusion may have...greater potential for contamination than the leachate produced by hydraulic flow. (p.358)