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The primary objective of this study was to determine whether or not trace organic compounds of the U.S. Environmental Protection Agency (EPA) priority pollutant list could be extracted from treated polyvinyl chloride (PVC) well casing that had been constructed with the use of PVC solvent cement and a composite epoxy-fiber reinforced casing.
Sections of PVC well casing were glued together with PVC solvent cement. In an effort to create a barrier that would reduce the leaching of various compounds from the PVC and the adhering cement, three treatments of PVC well casing were executed. PVC well casing was sulfonated with dry nitrogen gas-enriched with sulfur trioxide (SO3) for 5 min, followed by a 3% calcium chloride (CaCl2) wash. The remaining two treatments applied to PVC pipe were a 3% CaCl2 wash and no treatment. A dwell-time study employing double-distilled water was carried out for a fortnight. Subsequently, the three leachates, the PVC solvent cement, the double-distilled water, and the 3% CaCl2 wash were analyzed for their components by gas chromatograph/mass spectrometer-specific ion monitoring (GC/MS-SIM). The results indicated that both sulfonation and the CaCl2 wash may act to minimize substances leaching out of the cement, but that this reduction fails to be sufficient enough to adequately protect water contained in such PVC well casing from contamination by substances leached from the cement. It has been ascertained that all detected contaminants originate from the PVC solvent cement. A field procedure is proposed for remedial action to remove PVC solvent cement contaminants from wells that have been thus contaminated.
An alternative to PVC well casing is fiberglass reinforced epoxy casing. Both powder (60 mesh, 200 mesh) and well casing were subjected to leachate tests. Of all the substances sought in these leachates, only cyclohexene oxide, bisphenol A, phenol, and di-n-butyl phthalate were detected, and these were encountered in the 200 mesh sample. It is hypothesized that grinding to 200 mesh exposes surfaces that would ordinarily not be exposed. A classical dwell-time study failed to confirm the presence of these compounds. As a result, a number of state agencies and EPA have approved the use of fiberglass reinforced epoxy casing for drinking water wells and monitoring wells for Superfund sites.
chemical composition, dwell-time study, PVC well casing, fiberglass reinforced epoxy well casing, priority pollutants
Associate environmental consultant, Health and Environmental Sciences in Department of Aquatic Toxicology, Midland, MI