Pump-and-Treat Remediation of Chlorinated Solvent Contamination at a Controlled Field-Experiment Site

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• 作者：Michael O. Rivett ; Steven W. Chapman ; Richelle M. Allen-King ; Stanley Feenstra ; John A. Cherry
• 刊名：Environmental Science & Technology
• 出版年：2006
• 出版时间：November 1, 2006
• 年：2006
• 卷：40
• 期：21
• 页码：6770 - 6781
• 全文大小：613K
• 年卷期：v.40,no.21(November 1, 2006)
• ISSN：1520-5851

文摘

Pump-and-treat (P&T) remediation and associatedconcentration tailing are investigated at the field scale ina mildly heterogeneous sandy aquifer through theextraction of dissolved chlorinated solvent plumes thathad developed over 475 d from a multicomponent densenonaqueous-phase liquid (DNAPL) source intentionallyemplaced in the aquifer at the Borden (ON) research site.Extraction was accomplished via a source-containmentwell located 25 m from the source and two furtherdowngradient plume-centerline wells to remove theadvancing high-concentration dissolved plumes. The 550days of detailed P&T field data demonstrated the following:remediation, albeit slowly, of the leading 25-60 m plumesection to around typical drinking water standardconcentrations; concentration tailing (reduction) over 4orders of magnitude in the plume; a steady-state concentration"plateau" in the source-containment well capturing thesteadily dissolving DNAPL source; influences of extractionrate changes (concentration rebounds); and, lengthytailing from inter-well stagnation-zone areas. Much of thecontaminant behavior during the P&T appeared to be"ideal" in the sense that with appropriate specification ofthe source term and pumping regime, it was reasonablypredicted by 3-dimensional numerical model (HydroGeoSphere) simulations that assumed ideal (macrodispersion,linear sorption, etc.) transport. Supporting lab studiesconfirmed nonideal sorption was, however, important atthe point sample scale with enhanced PCE (tetrachloroethene)sorption to low- and high-permeability strata and moderatenonlinear and competitive sorption influences. Althoughthere was limited evidence of nonideal tailing contributionsto the field data (underprediction of some tailing curvegradients), such contributions to P&T tailing were not easilydiscerned and appeared to play a relatively minor rolewithin the mildly heterogeneous aquifer studied.