Evaluation of organic substrate for composting hydrocarbon contaminated flare pit soils

A series of full-scale windrow experiments have been conducted at the Olds College Composting Technology Centre (OCCTC) to evaluate the effectiveness of different organic substrates for remediation of hydrocarbon-contaminated flare pit soils. The purpose of organic matter addition to the soil was to encourage the indigenous soil microorganisms to flourish. Careful selectio n of the organic matrix was crucial for providing an environment conducive to co-metabolism of organic substrates and the contaminants. Furthermore, t he organic amendment enhances the ability of the composted soil to support vegetation which is an important attribute for reclamation purposes. A total of three dynamic windrows of 25-60 m(3) volume were constructed and evaluated at the OCCTC over two years. The organic amendment selection pro cess took into account the physical, chemical, and biological characteristi cs of the feedstock. Another practical aspect for the choice of organic ame ndment was the availability and proximity to the site of excavation. It is anticipated that full-scale implementation of the technology would occur on site and usually involve large volumes of amendments. This paper summarizes the results of the utilization of cattle manure, chic ken litter, wood chips, and pulp mill sludge as organic amendments for comp osting various types of flare pit soils with variable contamination levels.