Determination of the effect of exposure to gasoline components on a high density polyethylene geomembrane using the comprehensive test system

The comprehensive testing system (CTS) for geomembranes was used to test th e compatibility of high-density polyethylene (HDPE) geomembrane landfill li ner material with chemicals typically found in motor vehicle fuel. The CTS is a testing apparatus specifically designed to test the effects of simulta neously applying mechanical load, fluid head, and chemical exposure on the geomembrane. A combination of these factors is present on the geomembrane m aterial in service, and the CTS provides a laboratory reproduction of actua l field conditions. The article provides a description of gasoline based up on the desirable qualities of gasoline and provides background on testing o f rubbers used in gasoline-powered engine parts. The test's chemicals were gasoline, motor oil, benzene, ethylbenzene, toluene, xylenes, and iso-octan e (2,2,4 trimethyl pentane). This work found that gasoline had an effect on the geomembrane greater than the effect of any of the pure chemicals excep t ethylbenzene. Benzene, and the other aromatic compounds (ethylbenzene, to luene, and xylenes) are typically the primary regulatory concerns at fuel c ontaminated sites. The fact that gasoline had a greater effect on the perfo rmance of the HDPE geomembrane indicated that chemicals are present in gaso line which can decrease the performance of the containment structures used to hold gasoline, while not having a significant health risk. The clear imp lication is that risk assessments conducted on facilities must not only inc lude the health risks of chemicals placed in a facility, but must also cons ider the effect of the chemical on a containment structure. The fact that l ow-health-risk chemicals may have a great impact on the effectiveness of co ntainment structures leads to a possible synergistic mechanism where the lo w-health-risk chemicals enable a pathway for greater-health-risk chemicals to enter the environment. (C) 1999 Elsevier Science B.V. All rights reserve d.