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Groundwater in Soils and Bedrock Treated at an Industrial Site, Sweden


A single application provides enhanced reductive dechlorination in both aquifers

with Arkil A/S Miljøteknik and WSP

Groundwater-in-Soils-and-Bedrock-Treated-at-an-Industrial-Site-Sweden-Summary Groundwater in Soils and Bedrock Treated at an Industrial Site, Sweden

Introduction

Extensive chlorinated solvent contamination was discovered during the redevelopment of a former manufacturing facility into residential properties. Low but persistent concentrations of TCE were present within the soil and groundwater and the contamination had infiltrated the underlying fractured mudstone bedrock.

A remedial solution was required that would address the groundwater contamination in the bedrock and sorbed contamination in the soils.

icon-pdf Groundwater in Soils and Bedrock Treated at an Industrial Site, SwedenDownload the pdf

CS_Reg_1606_JaS44033_TCE_3DMe_SE-SiteMap Groundwater in Soils and Bedrock Treated at an Industrial Site, Sweden

Plume spread and location

Treatment

3-D Microemulsion (3DMe), an advanced self-distributing and long-lasting electron-donor technology developed by REGENESIS, was selected to enhance the natural process of anaerobic bioremediation. 3DMe stimulates and maintains enhanced reductive dechlorination (ERD) for an extended period from a single injection.

The 3DMe application was completed across the 4,050 m2 area using 51 direct push injection points to target the shallow soils. 32 injection wells were also used, allowing application into the bedrock and unconsolidated soils above.

In total 143,000 L of 3Dme was injected over 43 days. Remediation then continued in situ with no further onsite works required.

As the injections were carried out in November, the ambient temperature was -20°C and the ground was frozen. Therefore, the solution was warmed to 40°C prior to injection.

CS_Reg_1606_JaS44033_TCE_3DMe_SE-3DMe-Molecular-Structure Groundwater in Soils and Bedrock Treated at an Industrial Site, Sweden

3DMe’s molecular structure

ARKIL-Rigs_Pic5_Helsingborg_F-086 Groundwater in Soils and Bedrock Treated at an Industrial Site, Sweden

Drill rigs performing direct injection
(photo: Arkil)

ARKIL_Heating-Sit-pic4_Helsingborg_F-086 Groundwater in Soils and Bedrock Treated at an Industrial Site, Sweden

The heating of 3DMe to 40°C prior to injection
(photo: Arkil)

WSP-Result-Graphs_Helsingborg_GB Groundwater in Soils and Bedrock Treated at an Industrial Site, Sweden

Chlorinated solvent concentrations over time (Results Graphs: WSP)

Results

The ideal conditions for ERD were quickly established by the application, resulting in the rapid reduction in TCE within the groundwater in the bedrock aquifer. Degradation of the parent compound in the soils aquifer took a little longer to occur, but once established, full reductive dechlorination of the contamination was evident.

TCE concentrations have reduced from 500ug/L to almost non-detect in the bedrock and have decreased to 100ug/L in the soil aquifer and is continuing to reduce. Full reductive dechlorination is occurring in both aquifers with no problematic increase in daughter products.

Conclusion

  • A single application of 3DMe provided full reductive dechlorination of the contamination from a single application.
  • Successful treatment was made in two aquifers at the same time; in unconsolidated soils and underlying bedrock.
  • The freezing conditions on site did not impede the injection works, nor the in-situ remediation of the contamination.