Raleigh Former Gas Station

The site is a former gas station located in Raleigh, North Carolina. The site was contaminated with benzene, toluene, ethylbenzene, xylene (BTEX), chlorobenzene, naphthalene, dichlorobenzenes, and isopropylbenzene.

The area of concern was approximately 2,100 sq ft with a target vertical interval from 12 to 30 feet below ground surface (ft bgs). The geology at the site is primarily sandy silt with depth to groundwater at approximately 16 ft bgs.

IET developed the remedial design and applied Provect-OX to the subsurface via a patented injection process (US Patent 7,044,152) such that the activation processes occur in a controlled manner.

A total of 11 injection points and 3,600 lbs of Provect-OX were utilized to treat the two areas of concerns. The Provect-OX technology rapidly oxidizes the organic contaminants present in soil and groundwater and provides long-term, sustained secondary bioremediation to manage residuals and prevent contaminant rebound.

This is accomplished by using ferric iron (Fe III) as a safe and effective means of activating persulfate, which rapidly yields sulfate and ferrate radicals for chemical oxidation treatment. The process also enhances subsequent utilization of sulfate and iron as terminal electron acceptors for facultative redox reactions to support secondary biodegradation of any residual contaminant mass.

Following the Provect-OX application, petroleum hydrocarbon groundwater concentrations in both target monitoring wells have significantly decreased.

Additional contaminant concentration decreases in MW-1 are expected due to the iron and sulfate enhanced bioremediation processes.

Provect-OX is a self-activating, sustained-release chemical oxidant combining hydrogen peroxide and calcium peroxide in a proprietary formulation. Unlike conventional ISCO reagents requiring external activation, Provect-OX generates its own activation chemistry through controlled calcium peroxide decomposition — producing dissolved oxygen and free radical species over an extended period. IET's patented injection process (US 7,044,152) ensures the activation occurs in a controlled manner in-situ, preventing the rapid oxidant depletion that causes contaminant rebound.

The ferric iron (Fe III) activation system is a key differentiator: it safely activates persulfate to yield sulfate and ferrate radicals for chemical oxidation, while simultaneously enhancing subsequent utilization of sulfate and iron as terminal electron acceptors for facultative biological processes. This dual-phase mechanism — chemical oxidation followed by enhanced bioremediation — provides both rapid contaminant destruction and long-term residual treatment that prevents rebound.

The 11 injection points and 3,600 lbs of Provect-OX across two areas of concern demonstrate a focused, targeted treatment approach. The non-detect results in MW-4 and 99% xylene reduction in MW-1 within one year confirm the effectiveness of this dual-phase technology for petroleum-contaminated sites where both source destruction and long-term biological polishing are needed.

Raleigh, North Carolina is located in Wake County within the Piedmont physiographic province. The shallow geology consists of Precambrian-age metamorphic rocks — predominantly gneiss and schist of the Raleigh Gneiss Formation — overlain by residual soil (saprolite) formed by deep in-place weathering. The saprolite is typically clay-rich with moderate permeability, creating conditions suitable for in-situ remediation via direct push injection.

The two areas of concern at this site likely represent distinct contaminant source zones — possibly from historical petroleum storage or industrial operations. The targeted treatment approach with 11 injection points across two areas reflects IET's strategy of focusing amendment delivery on the highest-concentration zones rather than blanket-treating the entire site, optimizing both treatment effectiveness and project cost.