Central New York Former Gas Station

Chemical oxidation was used to degrade benzene, toluene, ethylbenzene and xylene (BTEX) compounds present in soil and groundwater at a site in Central New York during October 28-29, 2009.

Utilization of free radical chemistry, oxidation chemistry and facultative biological oxidation was implemented in such a way as to extend the oxidant and free radical residuals while enhancing the in-situ environment so that it is suitable for biologically based attenuation.

The 39 injection events were distributed to the subsurface via alphanumeric points. The programs were designed to influence an approximate area of 9,225 sq ft over an eight foot vertical zone.

The two phase program effectively introduces the remedial chemicals sodium persulfate, hydrogen peroxide and zero-valent iron (ZVI) directly into the soil and groundwater using direct push technologies, and retractable injection points through which the remedial materials were pumped into the targeted zones.

Phase one of the degradation program targeted BTEX compounds via hydroxyl and sulfate free radicals, the second utilized the decomposition products of the phase one reactions to effect facultative biological activity. A modified Fenton's chemistry and persulfate chemistry was integrated at the site, utilizing zero-valent iron as a catalyst for both reactions.

Total VOC concentrations decreased by 56% site-wide in the year following the remedial event. The biological stage of the remedial event was dominating one year after injection.

This Central New York rest-stop project demonstrates IET's two-phase treatment technology — combining sodium persulfate, hydrogen peroxide, and ZVI in a patented (US 7,044,152) single injection event. The ZVI catalyst activates both persulfate (generating sulfate radicals) and peroxide (generating hydroxyl radicals), creating a dual-radical oxidative environment that destroys BTEX, MTBE, naphthalene, and trimethylbenzene in both soil and groundwater.

Phase one targets BTEX compounds via hydroxyl and sulfate free radicals, while phase two utilizes the decomposition products of the phase one reactions to drive facultative biological activity. The modified Fenton's chemistry and persulfate chemistry, integrated using ZVI as a catalyst for both reactions, enables both oxidation and biological treatment from a single injection event — eliminating the need for multiple mobilizations.

The 56% site-wide VOC reduction and 94.5% benzene reduction at MW-2 within one year demonstrate the effectiveness of this dual-phase approach. The biological stage becoming dominant one year after injection confirms that the spent oxidant by-products successfully transitioned the site from active chemical oxidation to sustained biological treatment — providing the long-term treatment needed for complete petroleum site closure without repeated field events.

The active rest-stop site in Central New York likely sits on glacial till and lacustrine deposits characteristic of the region's Quaternary geology. The BTEX, MTBE, naphthalene, and trimethylbenzene contaminants of concern are typical of petroleum releases from underground storage tank (UST) systems at highway rest stops — where fueling operations and tank systems have historically been sources of soil and groundwater contamination.

The direct push injection technology used for this project enabled rapid, low-impact reagent delivery at an active rest-stop facility without disrupting operations. The retractable injection points allowed precise placement of remedial materials at the target treatment depths, ensuring that the dual-oxidant chemistry contacted both the source zone contamination and the dissolved-phase plume. The active rest-stop remaining operational throughout treatment demonstrates the key advantage of in-situ remediation at publicly accessible facilities where service interruption is not an option.