Case Study:

Residential UST Spill Remediation in North Vancouver BC: In-Situ Chemical Oxidation Success

North Vancouver BC In-Situ Chemical Oxidation

An in-situ chemical oxidation (ISCO) remediation was conducted at a residential property in North Vancouver to address petroleum hydrocarbons (LEPH), phenanthrene, and pyrene contamination in 200 m³ of impacted soil and groundwater following a heating oil UST leak that migrated under the building foundation, causing vapour intrusion and free product in property sumps. A 2.5-meter injection radius was used for targeted treatments within the basement and exterior property foundation, utilizing directional injections and drive-points to reach both saturated and unsaturated zones. TRIUM leveraged the property’s sump system to artificially raise the groundwater level, creating a fully saturated treatment zone. Over seven days, 24 basement injections and 3 exterior injections delivered 20,104 litres of sodium persulfate, blended using TRIUM’s TriOx process with specialized activation products. The treatment successfully met regulatory soil, groundwater, and vapour guidelines, required only six weeks for completion, and allowed the property owner to safely return home with minimal disturbance.

Project Details:

Location:

North Vancouver BC

Site:

Residential Property UST Spill

Date:

2020
to
to
Present

Contaminant of Concern:

Petroleum Hydrocarbons (LEPH), phenanthrene, pyrene

Impacted Media and Volume:

200 m3 impacted soil and groundwater

Project Tasks:

Remediation Design, Blending, Field applications, Performance Monitoring

The Problem:

An underground storage tank containing heating oil had leaked off-site onto a residential property and migrated under the building foundation. Impacts under the basement resulted in vapour intrusion in the basement and free product in property sumps.

The Approach:

In-situ chemical oxidation (ISCO) program based on 2.5 meter injection radius of influence within the basement of the impacted property, as well as surface application and directional injection on the exterior property foundation. Injections were conducted using drive-points to target various depth intervals within saturated and unsaturated zones. Due to shallow groundwater levels at the property, a sump exists to artificially lower the groundwater and prevent flooding of the basement. TRIUM utilized this to increase the groundwater level, thereby creating a fully saturated treatment zone.

Over 7 days, advanced 24 injection points in the basement and 3 on the exterior of the property. A total of 20,104 litres of sodium persulfate was injected at the site. Blending is site specific following TRIUM’s TriOx process and utilizing appropriate activation products.

The Results:

  • Confirmatory soil, groundwater, and vapour samples following injections met applicable guidelines
  • Minimal disturbance treatment option with 6-week treatment time-frame
  • Property owner provided clearance to return to home after remediation
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