Innovative Combined Amendment Approach Successfully Applied to Treat PHC Levels

Estimated Reading Time: 2 minutes

Project Highlights

  • Site previously treated with a series of RegenOx® and ORC Advanced® amendments significantly reduces plume concentrations. Remaining hot spot was then treated with turn-key injection application of PersulfOx® and ORC Advanced technologies bringing closure to facility
  • Successful turn-key treatment of offsite hot spot completed within five days
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Project Summary

An active gas station, identified by the State of Washington Department of Ecology as one of five LUST sites within one mile of Vancouver’s three groundwater monitoring wells, had entered into the state’s Voluntary Cleanup Program (VCP) in 2006 subsequent to shutdown of the onsite air-sparge/vapor extraction (AS/VE) system. This system had historically been employed at the site to supply oxygen for remedial purposes and address subsurface contamination that was first discovered beneath the dispenser islands in 1993. While prior applications of RegeneOx and ORC Advanced were effective in mitigating onsite contamination, PHC levels remained above MTCA criteria offsite hindering achievement of regulatory closure.

Antea® Group—the environmental consulting firm charged with remediation—partnered with REGENESIS® to implement a remedial strategy and technical design, which included the turn-key injection application of PersulfOx and ORC Advanced technologies to address petroleum hydrocarbons (PHCs) using an in situ chemical oxidation (ISCO) and enhanced aerobic remediation approach. The hot spot injection application included one event of PersulfOx coapplied with ORC Advanced, using direct push technology (DPT) injection points throughout the 3200 sq. ft. treatment area through 40 DPT injection points.

Technology Description

RegenOx – An injectable two-part advanced in situ chemical oxidation (ISCO) reagent that combines a solid sodium percarbonate-based alkaline oxidant (Part A) with a liquid mixture of sodium silicates, silica gel and ferrous sulfate (Part B), resulting in a powerful technology that treats and destroys a wide range of target contaminants including both petroleum hydrocarbons and chlorinated compounds.

PersulfOx – An advanced ISCO reagent and all-in-one product with a built-in patented catalyst destroys organic contaminants found in groundwater and soil through abiotic chemical oxidation reactions.

ORC Advanced – An engineered, oxygen-release compound designed specifically for enhanced, in situ aerobic bioremediation of petroleum hydrocarbons in groundwater and saturated soils. ORC Advanced produces a controlled release of molecular oxygen accelerating aerobic biodegradation processes up to 100 times f aster than natural degradation rates.

Results

For the final application event, following five on-site working days, REGENESIS completed the hot spot application process during which 9,753 lbs. of PersulfOx and 2,240 lbs. of ORC Advanced were applied to the designated treatment area. First quarter sampling results post-application showed concentrations below MTCA criteria. Following three quarters of monitoring, remediation of this site will be complete.

About the Client

Antea Group is an international engineering and environmental consulting firm specializing in full-service solutions in the fields of environment, infrastructure, urban planning and water. With more than 3,000 employees in over 100 offices around the world, Antea Group serves clients ranging from global energy companies and manufacturers to national governments and local municipalities.

Efficient Application of Combined Amendments Reduces PHC Concentrations Below Washington MCTA Levels

Estimated Reading Time: 3 minutes

Project Highlights

  • In Situ injection application of PlumeStop® Liquid Activated Carbon™ and ORC Advanced® brings closure to facility identified as Leaking Underground Storage Tank (LUST) site
  • REGENESIS® Remediation Services (RRS) used a multi-point approach to efficiently inject the combined amendments, completing the application within 24 hours
  • PHCs in groundwater and soil reduced below Washington Department of Ecology’s Model Toxics Control Act (MTCA)
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2m 34s reading time

Project Summary

An active gas station in Bothell, Washington was listed as a LUST site by the State of Washington Department of Ecology after two subsurface investigations detected petroleum hydrocarbon (PHC) impacted soil and groundwater. Entering into the state’s Voluntary Cleanup Program (VCP) in 2001, the site continuously failed to meet regulatory requirements defined in the MTCA, despite several years of cleanup efforts using a soil vapor extraction (SVE) system and an air sparge (AS) system to remove contaminant concentrations from beneath the site. Charged with remediation, Antea® Group partnered with REGENESIS to implement a solution, which included in situ injection applications of PlumeStop and ORC Advanced technologies.

REGENESIS injected approximately 200 gallons of PlumeStop using strategically placed point locations to rapidly reduce contaminant concentrations. Direct Push Technology (DPT) was employed to advance injection points throughout the treatment zone. The following day, the solution was increased, for a total of 835 gallons of PlumeStop solution (as applied with water) injected within the targeted treatment interval to deliver the full volume of remediation ammendment and complete the application on schedule. A total of nine (9) PlumeStop DPT injection points were cleared to 5 ft. bgs pre-injection.

Additionally, 120 lbs. of ORC Advanced were applied in cleared boreholes via a backfilling method, which involved drilling to the target depth, retracting the rods and pouring the ORC Advanced slurry down open boreholes to approximately 5 ft. bgs in order to properly abandon points.

Technology Description

PlumeStop – An innovative groundwater remediation technology designed to address the challenges of excessive time and end-point uncertainty in groundwater remediation. PlumeStop is composed of very fine particles of activated carbon (1-2μm) suspended in water through the use of unique organic polymer dispersion chemistry. Once in the subsurface, the material behaves as a colloidal biomatrix binding to the aquifer matrix, rapidly removing contaminants from groundwater, and enhancing permanent contaminant biodegradation.

ORC Advanced – An engineered, oxygen-release compound designed specifically for enhanced, in situ aerobic bioremediation of petroleum hydrocarbons in groundwater and saturated soils. ORC Advanced produces a controlled release of molecular oxygen accelerating aerobic biodegradation processes up to 100 times f aster than natural degradation rates.

Results

During the course of the injection and at the end of the application, increases in groundwater levels, ORP (oxidation reduction potential), and dissolved oxygen were observed in monitoring wells in the treatment area. The successful application of both technologies was achieved within approximately 24 hours, despite the challenging glacial till geology known to the region. With field modifications, RRS was able to not only mitigate surfacing issues by switching to injection via injection-well application, but also achieve the desired distribution of the remediation substrate in the subsurface. The first quarter sampling results indicate that the contaminant concentrations are at non-detect. Following monitoring events over the next three quarters, this site will be closed and issued a No Further Action (NFA) from the Washington Department of Ecology.

About the Client

Antea Group is an international engineering and environmental consulting firm specializing in full-service solutions in the fields of environment, infrastructure, urban planning and water. With more than 3,000 employees in over 100 offices around the world, Antea Group serves clients ranging from global energy companies and manufacturers to national governments and local municipalities.

PHCs at Former Farming Site Successfully Remediated Using PersulfOx®

Estimated Reading Time: 2 minutes

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

Estimated Reading Time: 2 minutes

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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1m 41s reading time

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.