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<br /> ROW011SCUSSION
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<br /> The Use of]PVC Casing and Screen in
<br /> the Presence of Gasoiines on the
<br /> Ground Water Table
<br /> by G.W. Schmidt
<br /> The purpose of this discussion is to extend the placed in contact wit!t any gasol;ne.After the sections of
<br /> conclusions of the Field Report by A.L. Sykes, R.A. PVC screen were in the gasolines for 6.5 months, the%-
<br /> McAllister and J.B.Homolya titled"Sorption of Oran- were removed and,along with the control sample,were
<br /> ics by Monitoring Well Construction Materials,"pub- photographed under a scanning electron microscope
<br /> lished in Ground Water Monitoring Review.v.6,no.4, (Amray Model l OOOB)to observe any swelling or alters- _
<br /> 1986_ tion.The results are shown in Figure I, photograph
<br /> The authors should be commended for statistically (premium gasoline), photograph 2 (unleaded regular),
<br /> demonstrating that there are nosignificant d ifferences in photograph 3(leaded regi.-lar),and photograph 4(control
<br /> organic compound sorption between polyvinyl chloride sample not in any gasoline).
<br /> (PVC), polytetrafluoroethylene and stainless steel well The photographs(samples 1,2and3)clearlyshowno
<br /> casing when exposed to dissolved volatile organic hydro- changes in slot size of any of the PVC screens in contac-
<br /> carbonsof approximately 100 ppb concentrations(Sykes with gasolines compared to the control(sample 4).Even
<br /> et al.1986).The U.S.Environmental Protection Agency the fro ments on the"cut face"of each of the sections
<br /> (EPA)'has incorrectly concluded that FVC is not an show n , ,ration from long-term exposure to liquid
<br /> acceptable material for monitoring well construction gasohncs. From this study,the conclusion is clear that
<br /> because it"deteriorates when in contact with...aromatic Schedule 40,rigid,Type 1 PVC casing and screen can be
<br /> hydrocarbons"(EPA 1986).It has also been implied over used with confidence when monitoring for the occurrence
<br /> the past several years by both federal and state regulatory of gasolines on the ground water table.As Henry David
<br /> agencies that PVC casing will swell and deteriorate in the Thoreau said,"The question is not what you look at,but
<br /> presence of the aromatic fraction of liquid gasoline. what you see."The EPA and state regulatory agencit
<br /> Therefore,many regulators do not allow the use of PVC should recognize such confirmation data and eliminate
<br /> casing, and especially PVC screen, in monitoring wells unsubstantiated conclusions such as not recommending
<br /> because they erroneously believe that the swelling of the use of PVC casing and screen in the presence of
<br /> PVC in the presence of gasolines will cause the screen gasolines,
<br /> slots tG close and the casing to deteriorate. )References
<br /> It has been my observation in using PVC screen and
<br /> casinginmonitoring liquid gasoline onthegroundwater Sykes,A.L.,R.A.McAllister and J.B. Homolya. 1986,
<br /> Sorption of Organics by Monitoring Well Corsiruc-
<br /> table in many thousands of wells,over 13 years,that there tion Materials.Ground Water Monitoring Review.V. _
<br /> is neither swelling no.deterioration of PVC casing or 6,no.444-47.
<br /> screen. To demonstrate these field observations, small U.S. Environmental Protection Agency. 1986. RCRA
<br /> sections of rigid 2-inch diameter, Type I PVC screen Ground Wader Monitoring Technical Enforcement
<br /> (0,006 slot size) were placed in different gasolines to Guidance Do-mment.0SWER-9950.1,pp.78-79.
<br /> record any changes in slot opening sizes or any other
<br /> alterations. Each PVC screen was cut to include two Biographical Sketch
<br /> slots,as well as being cut at right angles to the slots.The Gene IF Schmidt is director of Ground Water
<br /> sections were completely submerged in premium, un- Managrmnit in the Environmental Affairs and Safety
<br /> = Ier:ded regular, and leaded regular grades of Amoco Departmentofthe Amoco Corp.(P.O.Box 338S,Tulin.
<br /> gasolines. A control sample was retaince that Has not OK 74101).
<br /> 94 Spring 1987 GWNIR
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