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Gary Wealthall

Chlorinated Solvent DNAPL Bioremediation Pilot Test Demonstration in Denmark

2026-04-02T15:02:16-06:00February 23rd, 2016|Tags: , , , , , , |

Groundwater supplies beneath the Kærgård Plantage pharmaceutical waste disposal site in Denmark are contaminated with substantial quantities of chlorinated solvents (primarily tetrachloroethene, or PCE), which are present in the subsurface as dense non-aqueous phase liquids (DNAPLs). Contaminated groundwater from the site discharges to the nearby North Sea, creating a potential human health and ecological risk at a beach adjacent to the site. Since 2004, Geosyntec Consultants has advised the Danish government regarding the remedial strategy for cleaning up the site and mitigating risks at the beach. At Geosyntec’s recommendation, the Danish authorities retained a team of consultants with a goal of evaluating the feasibility of three technologies for remediating the primary DNAPL source areas at the site: in situ biological enhanced reductive dechlorination (ERD), in situ chemical oxidation with Fenton’s reagent, and in situ thermal remedial via steam flushing.

Pilot Demonstration of In Situ Alkaline Hydrolysis of Organophosphorus Pesticides in Denmark

2026-04-02T15:02:17-06:00February 23rd, 2016|Tags: , , , , , , |

The Høfde 42 pesticide waste disposal site is recognized as the most toxic contaminated site in Denmark. Between 1953 and 1962, the agrichemical manufacturing company Cheminova, with approval of Danish authorities, disposed of hundreds of tons of organophosphorus pesticide (OPP) and pesticide manufacturing wastes in pits at this site, which is located at a beach adjacent to the North Sea. A remedial feasibility study completed by the Danish government determined that in situ alkaline hydrolysis (ISAH) is the most cost effective technology for remediating groundwater and the residual wastes at the site. The Danish government, with funding by the European Union Life Program, selected the team of Geosyntec, COWI A/S, Tufts University, Nasus Water, and the University of Aalborg to conduct three pilot tests to compare three techniques for optimizing pesticide treatment by ISAH: 1) groundwater recirculation; 2) surfactant-enhanced flushing; and 3) acoustic vibration. In all three, tests a primary challenge is to inject strong base [caustic, or sodium hydroxide (NaOH)] to the in situ treatment zone while minimizing exposure of site workers to NaOH and pesticides.

Pilot Test of Bioremediation via Hydraulic Fracturing of Clay Till In Denmark

2026-04-02T15:02:17-06:00February 23rd, 2016|Tags: , , , , , , |

Until recently, biological in situ enhanced reductive dechlorination (ERD) was not a proven or validated technology in Denmark. Chlorinated solvents in groundwater are recognized as a widespread problem throughout the country, and the Danish government has funded a significant body of research to develop technologies for restoration of impacted groundwater impacted. For the former Funen County (now the Region of Southern Denmark) and the Danish Environmental Protection Agency, the team of Geosyntec, COWI A/S, and the Technical University of Denmark (DTU) developed a scoring protocol for determining the suitability of a given chlorinated solvent-contaminated site for treatment by ERD.

Electrokinetic-Enhanced Bioremediation of Chlorinated Solvents Technology Evaluation for Source Area Remediation in Clay Till in Denmark

2026-04-02T15:02:17-06:00February 23rd, 2016|Tags: , , , , , , |

A significant portion of the near-surface geology in Denmark is comprised of glacial moraine deposits, much of which consists of clayey till. Consequently, subsurface releases and spills of chlorinated solvents at industrial facilities in Denmark often end up as a sorbed phase or nonaqueous phase liquid (NAPL) that resides in clayey till. After a chlorinated solvent has escaped into subsurface clay, it can be extremely difficult and costly to recover the solvent or remediate the clay due its very low permeability. In situ remediation technologies that may succeed at treating chlorinated solvents in sand and gravel aquifers often will fail in clayey till. Electrokinetic-enhanced bioremediation (EK-BIO) is an innovative technology for improving remediation in low-permeability formations such as clay till by using direct current (DC) electric fields to facilitate subsurface transport and delivery of bioremediation agents such as electron donors and dechlorinating bacteria. Recognizing that Geosyntec is one of the only engineering consulting firms that possesses expertise with this technology, the Capitol Region of Denmark retained the team of Geosyntec, NiRAS, and the U.S. Army Environmental Research and Development Center (ERDC) to design and execute an EK- BIO pilot test in clayey till at a Danish site.

Bioremediation of Chloroethenes via Groundwater Recirculation Field Demonstration in Denmark

2026-04-02T15:02:20-06:00February 23rd, 2016|Tags: , , , , , , |

There are over 11,800 sites in Denmark where groundwater supplies are known to be contaminated, an estimated 1400 of which are contaminated with chlorinated solvents. Accordingly, remediation of contaminated groundwater is an important priority in Denmark as more than 90% of Danish drinking water is derived from groundwater. Biological in situ enhanced reductive dechlorination (ERD) has been recognized as a potentially cost-effective technology for remediating chlorinated solvents in groundwater; however, until recently, the capabilities of ERD as a groundwater treatment technology had not been rigorously demonstrated in Denmark. Consequently, the Danish Environmental Protection Agency and the former Funen County commissioned a field demonstration to quantify the performance of ERD at a Danish site. A team of bioremediation experts consisting of Geosyntec, COWI A/S, and the Danish Technical University (DTU) was selected to conduct the demonstration.

Jet Injection of Zero Valent Iron into Glacial Clay Till Pilot Test Demonstration in Denmark

2026-04-02T15:02:21-06:00February 23rd, 2016|Tags: , , , , , , |

Microscale zero valent iron (mZVI) and nanoscale ZVI (nZVI) are often effective amendments for remediation of chlorinated solvents in aquifers, but success with mZVI and nZVI in aquitards such as clay till is rare when conventional injection techniques are used. Jet Injection, a technology developed by FRx that involves a combination of hydraulic fracturing and jetting, was previously demonstrated to effectively distribute sodium permanganate in a tight clay formation. Jet injection forces large volumes of water under very high-pressure into the subsurface inducing fractures that can be filled and further propagated with a slurry of remediation treatment agents such as permanganate or mZVI. Recognizing that Geosyntec possesses expertise with this technology, the Capitol Region of Denmark retained the team of Geosyntec, FRx, and COWI A/S to design and execute a jet injection pilot test in clay till at a Danish site.

In Situ Bioremediation of Chlorinated Solvents in Frankfurt, Germany

2026-04-02T15:02:24-06:00February 23rd, 2016|Tags: , , , , , , |

Results of an enhanced in situ reductive dechlorination (ERD) pilot test performed at the site by another consultant in 2006 indicated that ERD will be an effective remedy for the chlorinated solvent source areas. Geosyntec was retained to negotiate regulatory approval for, and to design, implement, and construct, a full-scale ERD system at the site.

Screening Matrix for Pesticide Treatment Alternatives in France

2026-04-02T15:02:26-06:00February 23rd, 2016|Tags: , , , , , , |

Geosyntec was retained to review treatment alternative for brominated pesticide compounds found to exist in soil and groundwater beneath a former manufacturing facility in France. Geosyntec conducted a literature review of public and internal data and evaluated the expected fate of the brominated compounds from soil to groundwater and also to vapor pathways. After evaluating the potential for fate and transport Geosyntec developed a technology treatment screening matrix. The matrix included sustainability in the evaluation criteria.

Enhanced In Situ Bioremediation Biobarrier to Treat Chlorinated Ethenes in Switzerland

2026-04-02T15:02:29-06:00February 23rd, 2016|Tags: , , , , , , |

Geosyntec was retained to provide technical support on the design and implementation of an enhanced in situ bioremediation (EISB) biobarrier for the treatment of chlorinated ethenes in soil and groundwater beneath an active manufacturing facility. The goal of the project was for Geosyntec to develop implementation plans and design details so that equipment and materials could be procured locally.

Delineating the Distribution of Chlorinated Solvent DNAPL in Fractured Till and Bedrock at a Danish Megasite

2026-04-02T15:02:21-06:00February 23rd, 2016|Tags: , , , , , , |

The Naverland 26 site in Albertslund, Denmark was operated as a large-scale dry cleaner from 1965 to 1983. During this period, an estimated 5,000 tons of perchloroethene (PCE), 1,500 tons of trichloroethene (TCE), and 200 tons of 1,1,1-trichloroethane (TCA) were handled. PCE was delivered in tankers and transferred to an underground storage tank, while TCE and TCA were delivered and stored in drums. Previous studies at and around the site revealed extensive groundwater contamination from spilled or leaked chlorinated solvents, which likely resulted in the lateral and vertical migration of solvent dense nonaqueous phase liquid (DNAPL) through the clay till and into the limestone underlying the site.

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