Horsham Manufacturing Facility

The site has historically had soil and groundwater impacted by the use of degreasing agents, tetrachloroethene (PCE) and trichloroethene (TCE). The in-situ pilot injection program targeted these compounds and their anaerobic daughter products.

A total of 19 injections were made in May and June 2009 over 2 days including the use of an infiltration gallery, direct push points, and a deep injection well. The injections were made at 55-70 feet bgs in the deep bedrock zone, at 3-7 feet bgs using the infiltration gallery, and at 8-12 feet bgs in the direct push area.

The injection program utilized direct-push technology to apply blue green algae and kelp, essential nutrients (o-PO₄⁺ and NH₄⁺), sodium sulfite, calcium propionate, yeast extract, zero-valent iron (ZVI), EHC, and hydrogen release compounds (HRC-X and HRC).

The objectives of the program were to establish and maintain a stable dissolved hydrogen level, provide micro-nutrients, maintain pH, provide for optimal competitive conditions for the desired microbial consortia while minimizing the impact to the day-to-day operations of the facility (U.S. Patent 7,129,388).

Blue green algae and kelps were added in conjunction with organic hydrogen donors to provide necessary volatile fatty acids, as well as essential vitamins and nutrients for biological activity.

This Horsham project demonstrates IET's patented (US 7,129,388) multi-amendment enhanced reductive dechlorination (ERD) approach — combining blue green algae, kelp, calcium propionate, yeast extract, sodium sulfite, ZVI, EHC, and hydrogen release compounds (HRC-X and HRC) in a single injection program. The staggered fermentation profile of these multiple organic substrates provides sustained hydrogen release from 0 to 1,500+ days, creating the continuous low-level hydrogen flux that selectively stimulates dechlorinating bacteria over competing methanogens.

The multi-depth injection strategy — targeting both bedrock fractures and overburden — demonstrates IET's capability to treat complex sites where contamination spans multiple geological units. Deep well injection addresses bedrock fracture contamination, while direct push injection targets the overburden zone, and the infiltration gallery provides broad-area shallow treatment. This three-pronged delivery approach ensures comprehensive treatment coverage across the site's heterogeneous subsurface.

The zero operational disruption result is particularly significant — the facility maintained normal operations throughout the injection program, demonstrating that in-situ remediation can be performed at active industrial sites without impacting business continuity. The 99% total CVOC decrease in the direct push area and 100% TCE elimination demonstrate the effectiveness of the multi-amendment ERD approach in Pennsylvania's fractured bedrock and overburden settings.

Horsham, Pennsylvania is located in Montgomery County within the Piedmont physiographic province. The shallow geology consists of Precambrian-age metamorphic rocks of the Wissahickon Formation — predominantly schist and gneiss — overlain by residual soil (saprolite). The site's bedrock and overburden contamination reflects the dual-porosity nature of Piedmont hydrogeology, where contaminants migrate through both the weathered saprolite matrix and the fracture network in the underlying bedrock.

The multi-depth injection strategy used at this site — deep well, direct push, and infiltration gallery — is specifically designed to address the dual-porosity challenge. Deep well injection targets bedrock fractures where contaminants have migrated along preferential pathways. Direct push injection treats the saprolite overburden where contaminant mass is typically concentrated at the soil-bedrock interface. The infiltration gallery provides broad shallow treatment for any residual contamination in the uppermost soil zone.