TREATMENT OF PCP-CONTAMINATED SOIL USING AN ENGINEERED EX SITU BIOPILE PROCESS ON A FORMER WOOD TREATMENT SUPERFUND SITE

摘要

Releases of creosote and pentachlorophenol (PCP) at a New Brighton, Minnesota wood treatment facility, resulted in widespread soil and groundwater contamination. Site investigations lead to the facility's inclusion on the National Priorities List (NPL), and the Minnesota Pollution Control Agency was designated lead regulatory agency. Biological treatment was the preferred remedy for 18,000 yd~3 of contaminated soil, and Biogenie was contracted to design, construct and operate an ex situ Biopile to achieve the remedial objectives. Most project owners and remedial managers perceive the Biopile proc ess as a passive remediation technology, not fully appreciating the scientific and engineering expertise required to design and operate an effective Biopile. This paper highlights the "behind the scenes" efforts of the scientific and engineering team responsible for a Biopile project, and specifically how those efforts achieved difficult remedial objectives within a treatment performance guarantee contract. The New Brighton project required that an ex situ Biopile be used to achieve site reuse criteria of 10 mg/kg PCP and 5 mg/kg cPAHs, with a schedule dictating operation during winter months reaching -22℃. Biopile operating parameters were developed during laboratory Treatability Studies designed to optimize the biodegradation capacity of indigenous microorganisms. The TS included the configuration of miniature Biopiles with various amendment and operational strategies to stimulate and sustain preferential bacteria. Additionally, specific operational paramet ers were developed to biodegrade soil containing a large percentage of highly impacted woodchips. An engineering team applied the TS results during scale -up Biopile design and the project team mobilized to the site for construction. Average PCP reduction rates achieved 95% for soils (Phase Ⅰ) and 76% for soils containing wood chips (Phase Ⅱ), and over 96% of the contaminated soil achieved treatment criteria for reuse at the site.