Co-composting of residual fuel contamination in soil

A remediation program was designed and implemented at a site in southeaster n Australia that had become contaminated with nonvolatile, n-alkane total p etroleum hydrocarbons (TPH). The remediation was conducted in two stages. T he excavation, validation and reinstatement of two contaminated areas on th e site was first conducted, followed by development of a composting treatme nt process. The total volume of contaminated soil (i.e., TPH concentration > 1000 mg/kg C-10-C-36) was similar to 4300 m(3) with a concentration of 31 00 +/- 1270 mg/kg. The soil was stockpiled into four windrows, on a compact ed, bunded clay base. Approximately 35% (v/v) of raw materials (green tree waste, cow manure, gypsum, and nutrients) were added to initiate composting . The piles were kept moist during the summer months, but no other maintena nce was conducted. Once the composting process was initiated, the windrows were sampled at 2 and 6 months. After 6 months treatment, the average TPH c oncentration (C-10-C-36) was 730 mg/kg (with a 95% Cl of 1020 mg/kg), which met the relevant clean fill criteria applicable to the site. There were no other contaminants of significance in the treated soil compost and it pose d no unacceptable risk to human health or the environment, allowing it to b e used as fill at the site.