Groundwater Monitoring & RemediationVolume 41, Issue 4 p. 13-21 Columns Mass Flux Strategies 20 Years On—Getting the Sand Out of the Gears John Horst, Corresponding Author John Horst john.horst@arcadis.com Search for more papers by this authorMatthew Schnobrich, Matthew SchnobrichSearch for more papers by this authorCraig Divine, Craig DivineSearch for more papers by this authorPatrick Curry, Patrick CurrySearch for more papers by this authorShawn Sager, Shawn SagerSearch for more papers by this authorAllan Horneman, Allan HornemanSearch for more papers by this author John Horst, Corresponding Author John Horst john.horst@arcadis.com Search for more papers by this authorMatthew Schnobrich, Matthew SchnobrichSearch for more papers by this authorCraig Divine, Craig DivineSearch for more papers by this authorPatrick Curry, Patrick CurrySearch for more papers by this authorShawn Sager, Shawn SagerSearch for more papers by this authorAllan Horneman, Allan HornemanSearch for more papers by this author First published: 28 October 2021 https://doi.org/10.1111/gwmr.12491Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Volume41, Issue4Fall 2021Pages 13-21 RelatedInformation

It is important to estimate what light nonaqueous phase liquid (LNAPL) recovery can be practicably achieved from subsurface environments. Over the last decade, research to address this included a broad field program, laboratory measurements and experimentation, and modeling approaches. Here, we consolidate key findings from the research in the context of current literature and understanding, with a focus on a well-validated, multiphase multicomponent modeling approach to achieve estimates of reasonable endpoints for LNAPL recovery. Simple analytical models can provide approximate saturation distributions and estimates of LNAPL recoverability via transmissivity approximation, but are insufficient to predict LNAPL saturationand composition-based recovery endpoints for various recovery technologies. This is because they cannot account for multiphase, multicomponent fate and transport and key rocesses such as hysteresis. Rec nt advances to improve estimates of the fraction of recoverable LNAPL and its ransmissivity are summarized. These advances include further development and application of a w ll-validated model to characterize ac ive LNAPL recovery endpoints. We present key factors that affect the determination of LNAPL recovery endpoints, and outline how recovery endpoints are affected by natural source zone depletion (NSZD—currently gaining acceptance as a LNAPL remediation option). Major factors include geo-physical characteristics of the formation, magnitude of an LNAPL release and partitioning properties of the key LNAPL constituents of concern. Based on the capabilities of the validated model, the paper also provides a basis to optimize LNAPL recovery efforts.

The poly(methacrylic acid) (PMAA) was synthesized in the pores of commercial microfiltration PVDF membranes to allow incorporation of catalytic palladium/iron (Pd/Fe) nanoparticles for groundwater remediation. Particles of 17.1 ± 4.9 nm size were observed throughout the pores of membranes using a focused ion beam. To understand the role of Pd fractions and particle compositions, 2-chlorobiphenyl was used as a model compound in solution phase studies. Results show H2 production (Fe0 corrosion in water) is a function of Pd coverage on the Fe. Insufficient H2 production caused by higher coverage (> 10.4% for 5.5 wt%) hindered dechlorination rate. With 0.5 wt% Pd, palladized-Fe reaction rate (surface area normalized reaction rate, ksa = 0.12 L/(m2-h) was considerably higher than isolated Pd and Fe particles. For groundwater, in a single pass of Pd/Fe-PMAA-PVDF membranes (0.5 wt% Pd), chlorinated organics, such as trichloroethylene (177 ppb) and carbon tetrachloride (35 ppb), were degraded to 16 and 0.3 ppb, respectively, at 2.2 seconds of residence time. The degradation rate (observed ksa) followed the order of carbon tetrachloride > trichloroethylene > tetrachloroethylene > chloroform. A 36 h continuous flow study with organic mixture and the regeneration process show the potential for on-site remediation.

Groundwater Monitoring & RemediationVolume 39, Issue 1 p. 11-19 Advances in Remediation Solutions Groundwater Remediation in Low-Permeability Settings: The Evolving Spectrum of Proven and Potential by John Horst, Corresponding Author john.horst@arcadis.com Search for more papers by this authorCraig Divine, Search for more papers by this authorMatthew Schnobrich, Search for more papers by this authorRyan Oesterreich, Search for more papers by this authorJonah Munholland, Search for more papers by this author by John Horst, Corresponding Author john.horst@arcadis.com Search for more papers by this authorCraig Divine, Search for more papers by this authorMatthew Schnobrich, Search for more papers by this authorRyan Oesterreich, Search for more papers by this authorJonah Munholland, Search for more papers by this author First published: 08 January 2019 https://doi.org/10.1111/gwmr.12316Citations: 6Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinked InRedditWechat Citing Literature Volume39, Issue1Winter 2019Pages 11-19 This article also appears in:Virtual Issue: 2021 National Groundwater Awareness Week RelatedInformation

Groundwater Monitoring & RemediationVolume 38, Issue 4 p. 15-28 Columns Digital Reinvention in the Remediation Industry by John Horst, John HorstSearch for more papers by this authorWilco Kaijim, Wilco KaijimSearch for more papers by this authorNicklaus Welty, Nicklaus WeltySearch for more papers by this authorAndrea Rayner, Andrea RaynerSearch for more papers by this authorBenjamin Arancibia, Benjamin ArancibiaSearch for more papers by this authorShawn Burnell, Shawn BurnellSearch for more papers by this authorMonica Dupre, Monica DupreSearch for more papers by this authorMatthew Schnobrich, Matthew SchnobrichSearch for more papers by this authorFrançois Appéré, François AppéréSearch for more papers by this author by John Horst, John HorstSearch for more papers by this authorWilco Kaijim, Wilco KaijimSearch for more papers by this authorNicklaus Welty, Nicklaus WeltySearch for more papers by this authorAndrea Rayner, Andrea RaynerSearch for more papers by this authorBenjamin Arancibia, Benjamin ArancibiaSearch for more papers by this authorShawn Burnell, Shawn BurnellSearch for more papers by this authorMonica Dupre, Monica DupreSearch for more papers by this authorMatthew Schnobrich, Matthew SchnobrichSearch for more papers by this authorFrançois Appéré, François AppéréSearch for more papers by this author First published: 15 October 2018 https://doi.org/10.1111/gwmr.12304Citations: 1Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume38, Issue4Special Issue: Diagnostic Tools to Assess In Situ Remediation System PerformanceFall 2018Pages 15-28 RelatedInformation

Groundwater Monitoring & RemediationVolume 37, Issue 4 p. 15-22 Advances in Remediation Solutions Advancing Contaminant Mass Flux Analysis to Focus Remediation: The Three-Compartment Model by John Horst, John HorstSearch for more papers by this authorScott Potter, Scott PotterSearch for more papers by this authorMatthew Schnobrich, Matthew SchnobrichSearch for more papers by this authorNicklaus Welty, Nicklaus WeltySearch for more papers by this authorAnkit Gupta, Ankit GuptaSearch for more papers by this authorJoseph Quinnan, Joseph QuinnanSearch for more papers by this author by John Horst, John HorstSearch for more papers by this authorScott Potter, Scott PotterSearch for more papers by this authorMatthew Schnobrich, Matthew SchnobrichSearch for more papers by this authorNicklaus Welty, Nicklaus WeltySearch for more papers by this authorAnkit Gupta, Ankit GuptaSearch for more papers by this authorJoseph Quinnan, Joseph QuinnanSearch for more papers by this author First published: 05 December 2017 https://doi.org/10.1111/gwmr.12250Citations: 3Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume37, Issue4Fall 2017Pages 15-22 RelatedInformation

Groundwater Monitoring & RemediationVolume 37, Issue 3 p. 19-27 Advances in Remediation Solutions Digital Innovation: The Next Disruptive but Transformative Remediation Frontier by John Horst, John HorstSearch for more papers by this authorNicklaus Welty, Nicklaus WeltySearch for more papers by this authorMatthew Schnobrich, Matthew SchnobrichSearch for more papers by this authorPrasoon Sinha, Prasoon SinhaSearch for more papers by this authorPoonam R. Kulkarni, Poonam R. KulkarniSearch for more papers by this author by John Horst, John HorstSearch for more papers by this authorNicklaus Welty, Nicklaus WeltySearch for more papers by this authorMatthew Schnobrich, Matthew SchnobrichSearch for more papers by this authorPrasoon Sinha, Prasoon SinhaSearch for more papers by this authorPoonam R. Kulkarni, Poonam R. KulkarniSearch for more papers by this author First published: 25 September 2017 https://doi.org/10.1111/gwmr.12222Citations: 1Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume37, Issue3Summer 2017Pages 19-27 RelatedInformation

Sulfate reducing conditions are widely observed in groundwater plumes associated with petroleum hydrocarbon releases. This leads to sulfate depletion in groundwater which can limit biodegradation of hydrocarbons (usually benzene, toluene, ethylbenzene, xylenes [BTEX] compounds) and can therefore result in extended timeframes to achieve groundwater cleanup objectives by monitored natural attenuation. Under these conditions, sulfate addition to the subsurface can potentially enhance BTEX biodegradation and facilitate enhanced natural attenuation. However, a delivery approach that enables effective contact with the hydrocarbons and is able to sustain elevated and uniform sulfate concentrations in groundwater remains a key challenge. In this case study, sulfate addition to a groundwater plume containing predominantly benzene by land application of agricultural gypsum and Epsom salt is described. Over 4years of groundwater monitoring data from key wells subjected to pilot-scale and site-wide land application events are presented. These are compared to data from pilot testing employing liquid Epsom salt injections as an alternate sulfate delivery approach. Sulfate land application, sulfate retention within the vadose zone, and periodic infiltration following ongoing precipitation events resulted in elevated sulfate concentrations (>150 mg/L) in groundwater that were sustained over 12months between application events and stimulated benzene biodegradation as indicated by declines in dissolved benzene concentration, and compound-specific isotope analysis data for carbon in benzene. Long-term groundwater benzene concentration reductions were achieved in spite of periodic rebounds resulting from water table fluctuations across the smear zone. Land application of gypsum is a potentially cost-effective sulfate delivery approach at sites with open, unpaved surfaces, relatively permeable geology, and shallow hydrocarbon impacts. However, more research is needed to understand the fate and persistence of sulfate and to improve the likelihood of success and effectiveness of this delivery approach.Article impact statement: This is a case study of land application of sulfate salts to stimulate benzene biodegradation in a groundwater plume.

Groundwater Monitoring & RemediationVolume 37, Issue 2 p. 14-23 Advances in Remediation Solutions Three Decades of Solvent Bioremediation: The Evolution from Innovation to Conventional Practice by Suthan S. Suthersan, Suthan S. SuthersanSearch for more papers by this authorMatthew Schnobrich, Matthew SchnobrichSearch for more papers by this authorJennifer Martin, Jennifer MartinSearch for more papers by this authorJohn F. Horst, John F. HorstSearch for more papers by this authorEllyn Gates, Ellyn GatesSearch for more papers by this author by Suthan S. Suthersan, Suthan S. SuthersanSearch for more papers by this authorMatthew Schnobrich, Matthew SchnobrichSearch for more papers by this authorJennifer Martin, Jennifer MartinSearch for more papers by this authorJohn F. Horst, John F. HorstSearch for more papers by this authorEllyn Gates, Ellyn GatesSearch for more papers by this author First published: 06 June 2017 https://doi.org/10.1111/gwmr.1_12212Citations: 10Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume37, Issue2Spring 2017Pages 14-23 RelatedInformation

Groundwater Monitoring & RemediationVolume 36, Issue 4 p. 22-30 Advances in Remediation Solutions Rethinking Conceptual Site Models in Groundwater Remediation by Suthan S. Suthersan, Suthan S. SuthersanSearch for more papers by this authorScott T. Potter, Scott T. PotterSearch for more papers by this authorMatthew Schnobrich, Matthew SchnobrichSearch for more papers by this authorJennifer Wahlberg, Jennifer WahlbergSearch for more papers by this authorJoseph Quinnan, Joseph QuinnanSearch for more papers by this authorNicklaus Welty, Nicklaus WeltySearch for more papers by this authorTom Fewless, Tom FewlessSearch for more papers by this author by Suthan S. Suthersan, Suthan S. SuthersanSearch for more papers by this authorScott T. Potter, Scott T. PotterSearch for more papers by this authorMatthew Schnobrich, Matthew SchnobrichSearch for more papers by this authorJennifer Wahlberg, Jennifer WahlbergSearch for more papers by this authorJoseph Quinnan, Joseph QuinnanSearch for more papers by this authorNicklaus Welty, Nicklaus WeltySearch for more papers by this authorTom Fewless, Tom FewlessSearch for more papers by this author First published: 20 December 2016 https://doi.org/10.1111/gwmr.12192Citations: 12Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume36, Issue4Fall 2016Pages 22-30 RelatedInformation