PHCs at Former Farming Site Successfully Remediated Using PersulfOx®

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Project Highlights

  • Introduction of PersulfOx® resulted in reduction of PHCs in fractured bedrock, meeting site remediation goals
  • High sulphate concentrations in groundwater resulted from the application of PersulfOx which is assisting natural attenuation of any residual petroleum hydrocarbons
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Project Summary

A former farming facility located in Calgary, Alberta contained three above ground storage tanks (ASTs) and two pump islands. Environmental assessments related to the planned urban redevelopment of the former farming facility revealed contamination of the soil and groundwater beneath the site with petroleum hydrocarbons (PHCs) due to release(s) from the former ASTs. During a remedial excavation, PHC impacts above the applicable vapor inhalation guidelines were identified within the fractured bedrock. Given the nature and depth of the bedrock, the remedial excavation was no longer feasible. Therefore, PersulfOx, a proprietary chemical oxidant chemical, was utilized for in situ treatment of soil and groundwater within the excavation to reduce the remaining PHC concentrations below the commercial vapor inhalation guidelines.

Based on the subsurface investigations and monitoring activities prior and subsequent to the chemical application, it was determined that PersulfOx was effective in remediation of PHC impacts within the fractured bedrock in an open excavation, within a short period of time and under the low groundwater temperatures. Following treatment with PersulfOx, reduction or the absence in PHC concentrations has been observed in soil or groundwater samples and all post-remediation concentrations have remained below the vapor inhalation pathway guidelines for commercial use. However, high sulphate concentrations were identified as a result of this chemical application which over the long term would assist in the natural attenuation of any residual petroleum hydrocarbons.

Technology Description

PersulfOx is a chemical oxidant that rapidly reduces the mass of the contaminants. This chemical consists of 90% of sodium persulfate and 10% catalyst powder. PersulfOx is very effective in rapid oxidation of petroleum hydrocarbons in both soil and groundwater.

Results

Reduction of PHC concentrations by oxidation using PersulfOx facilitated the urban development of the former farming facility. The high sulphate concentrations are expected to attenuate to background concentrations with time as sulphate is an electron acceptor in the natural attenuation process of petroleum hydrocarbons.

Remediation Plan Completed in Two Days at Former Service Station. No Further Action Received Following Successful PlumeStop® Application

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Remediation of BTEX and PHC in the Greater Toronto Area Using PlumeStop

Project Highlights

  • Regulatory standards met following single injection of PlumeStop
  • Remedial injection event completed in two days with the first clean samples obtained within three weeks post-injection
  • Effective design and approach led to time and cost savings for the client
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Project Summary

A former gasoline retail station located in Whitby, Ontario, was the site of BTEX and PHC contaminants requiring remediation. Excavation, as well as pump and treat approaches, had been used to address contaminant levels, but groundwater remained impacted by BTEX and PHC F1 and F2 above regulatory standards. While the contractors were able to remove the majority of impacts, they were not able to remediate the site to the applicable regulatory standards.

The client hired INSITU Remediation Services LTD (IRSL), an environmental firm specializing in in situ remediation technologies, to reduce the levels and reach required standards safely and effectively following a tendered contract issued to a total of five contractors. IRSL was chosen based on their innovative approach and lower total cost. Using a proprietary design, IRSL injected PlumeStop Liquid Activated Carbon™, to remediate residual BTEX and PHC F1 and F2 groundwater impacts.

Technology Description

PlumeStop is an innovative in situ remediation technology designed to rapidly reduce contaminant concentrations, stop migrating plumes, eliminate contaminant rebound, achieve stringent cleanup standards and treat back-diffusing contaminants. PlumeStop provides a unique colloidal biomatrix platform which rapidly sorbs contaminants out of the dissolved-phase. Once contaminants are concentrated within the PlumeStop biomatrix, they can be completely biodegraded in place using compatible REGENESIS bioremediation products.

Results

The remedial program was completed in two days with the first clean samples obtained within three weeks post-injection. The BTEX and PHC plumes were treated to below the regulatory standards. Sampling has been performed over four quarters and the site has been deemed remediated.

About the Client

One of Canada’s most experienced remediation companies, INSITU Remediation Services Ltd. (IRSL) has designed, implemented, and maintained soil and groundwater remediation programs in diverse geological environments in North, Central, and South America, Europe and the Middle East.

Remediation of Impacted Groundwater on a Busy Construction Site, UK

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REGENESIS was asked to provide a remedial solution to mitigate against the off-site migration of the contaminated groundwater. We designed a PlumeStop barrier and was subsequently employed as subcontractor on the works. The barrier injections were made along the downgradient boundary of the site, targeting the groundwater in a gravel formation at 2 – 5m BGL. On this site, PlumeStop was co-injected with ORC-Advanced to enhance the aerobic biodegradation processes in the subsurface.Read More

Contaminant Concentrations at an Active Gas Station Reduced by 90% Using PersulfOx® and ORC Advanced®

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REGENESIS Uses an Outside-In Application to Push 30-Year Old LUST Case to Closure in Remote Region of Arizona

Project Highlights

  • Innovative “Outside-In” approach incorporated injection design working from perimeter of the treatment area first, and progressively working toward the center
  • First event application completed within seven days with a second event completed in nine days the following month without disruption to active site
  • Closely managed injection wells to ensure proper distribution and avoid surfacing
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Project Summary

An active gasoline station in Springerville, AZ was listed as a hazardous Leaking Underground Storage Tank (LUST) site by the state of Arizona. After 30 years of unsuccessful remediation using a number of approaches, REGENESIS Remediation Services (RRS) was contacted to perform two separate injection events approximately one month apart. Both events included injections at 15 injection points over a range of depths. The first round of injections included a combination of PersulfOx and ORC Advanced. The second round of injections contained only PersulfOx.

During both injections PersulfOx and ORC Advanced were successfully applied within the treatment area and at the targeted treatment interval of 18 to 60 ft. bgs. Low to moderate injection pressures and application flow rates were observed at each of the injection well locations, indicating good distribution of the amendments. Increases in dissolved oxygen, conductivity, pH, and oxidation-reduction potential were observed, indicating good distribution and influence of the PersulfOx and ORC Advanced remediation chemistry.

Technology Description

PersulfOx is an advanced in situ chemical oxidation (ISCO) reagent that destroys organic contaminants found in groundwater and soil through abiotic chemical oxidation reactions. It is an all-in-one product with a built-in catalyst which activates the sodium persulfate component and generates contaminant-destroying free radicals without the costly and potentially hazardous addition of a separate activator. The patented catalyst enhances the oxidative destruction of both petroleum hydrocarbons and chlorinated contaminants in the subsurface.

ORC Advanced is an engineered, oxygen release compound designed specifically for enhanced, in situ aerobic bioremediation of petroleum hydrocarbons in groundwater and saturated soils.

Results

Since the two injections have been completed, three rounds of groundwater monitoring have been performed. Benzene concentrations have been reduced by 90% to 20 μg/L. A closure request has been submitted by the client awaiting regulatory approval.

State-Funded Cleanup of Former Service Station on Reservation Land

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Enhanced Aerobic Biodegradation and In Situ Chemical Oxidation Provides Safe Approach to Remediate TPH-g and BTEX

Project Highlights

  • Extensive coordination was required between state-funded Pollution Liability Insurance Agency (PILA) of Washington and US EPA Region 10
  • Combined remedy approach using ORC Advanced® and PersulfOx® provided a safe solution for land used to raise livestock
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REGENESIS State funded cleanup case study

Project Summary

The site located in Wapato, Washington is a former gas station situated on Reservation Land with historical releases dating back >20 years. The site is regulated through US EPA Region 10 and was previously an empty lot used for ranging cattle.

Initial remedial activities included excavation of source-area soil, however persistent contamination remained. Concerns were raised regarding how amendments might affect livestock. As a result, the remediation approach needed to be environmentally benign. The revised remedial plan included Enhanced Aerobic Biodegradation (ORC Advanced) and In Situ Chemical Oxidation (PersulfOx) to reduce the remaining concentrations and meet regulatory goals.

Technology Description

PersulfOx is a chemical oxidant that rapidly reduces the mass of the contaminants. This chemical consists of 90% sodium persulfate and 10% catalyst powder. PersulfOx is very effective in rapid oxidation of petroleum hydrocarbons in both soil and groundwater.

ORC Advanced is an engineered, oxygen release compound designed specifically for enhanced, in situ aerobic bioremediation of petroleum hydrocarbons in groundwater and saturated soils.

Results

An integrated treatment strategy was devised, which included injections in three separate areas. Two areas were treated with PersulfOx and ORC Advanced. The third area was treated with ORC Advanced only.

The by-products of ORC Advanced and PersulfOx are both insoluble and non-toxic, making the application safe and effective. Consequently, there were no issues relating to the landowner’s concern for amendments affecting livestock. A total area of 4,100 ft2 was treated for high levels of BTEX and TPH-g. Monitoring is ongoing.