Highway Rest Stop — Bowmansville

The subject site is an active rest-stop along a major Pennsylvania highway. The site has been impacted by the historic release of petroleum fluids. The contaminants of concern are petroleum hydrocarbons, such as benzene and toluene.

The in-situ injection program targeted these compounds with 27 injections using synergistic catalyzed reactions and long lasting (via persulfate) oxidation. Injections occurred between 10 and 18 feet below ground surface over a span of 2 days in September 2007. The geology of the site is combination of silt and sand.

The remedial approach utilized both free radical chemistry, oxidation chemistry and facultative biological oxidation in such a way as to extend the oxidant and free radical residuals while enhancing the in-situ environment such that it was suitable for biologically based attenuation.

IET applied three remedial materials to the subsurface via a patented injection process and apparatus (US Patent 7,044,152) such that the oxidation reactions occurred in a controlled manner. In a unique application of zero-valent iron metal, IET activated both the persulfate and the peroxide species in-situ, allowing for both the oxidation and biological remedial processes to occur via a single injection event.

The premise of the approach is based on the utilization of oxidizing species and their by-products. The first phase, the oxidation event, chemically oxidizes the majority of dissolved and sorbed targeted compounds. Once the oxidants are exhausted, the ferric iron and sulfate species allow for the biological attenuation phase.

The groundwater results from the five monitoring wells within the injection area showed large reductions in petroleum hydrocarbons.