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Title: Bioremediation treatability study for remedial action at Popile, Inc., site, El Dorado, Arkansas. Phase II, Pilot-scale evaluation
Authors: Hansen, Lance D.
Nestler, Catherine C.
Channell, Michael G.
Ringelberg, David B.
Fredrickson, Herbert L.
Waisner, Scott A.
Keywords: Soils--Leaching--Arkansas
Polycyclic aromatic hydrocarbons--Arkansas
Publisher: Environmental Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Series/Report no.: ERDC/EL ; TR-00-13.
Abstract: A pilot-scale study of traditional landfarming techniques was conducted to evaluate the treatment requirements directed in the Comprehensive Environmental Remediation Compensation and Liability Act (CERCLA) Record of Decision (ROD) from EPA Region 6 for this site. The study was conducted to: (a) determine if treatment goals specified in the ROD were achievable for site soils (5-ppm benzo(a)pyrene [BaP] equivalents and 3-ppm pentachlorophenol [PCP]; (b) evaluate contaminant degradation kinetics; and (c) evaluate leaching potential of treated soil. Initial soil characterization (physical, chemical, biological) indicated a clay/silt soil (based on Atterberg limits and particle size distribution) with high contamination (polycyclic aromatic hydrocarbons [PAH] ≅ 13,000 ppm, PCP ≅ 775 ppm, BaP eq ≅ 105 ppm), and an indigenous biological community (approximately 107 cells/g as determined by ester linked polar lipid fatty acid (PLFA) analysis). Intermittently scheduled experimental analysis included contaminant concentration, nutrient concentration, pH, moisture, in situ respiration, and microbial community/biomass analysis. The pilot-scale site consisted of a modified RCRA secondary containment system that contained two, 3-cu yd land-treatment units (LTUs) designed to simulate field conditions. LTU 1 was cultivated on an oxygen-dependent basis. LTU 2 was cultivated on a fixed schedule. Soil moisture was maintained between 50% and 80% of field moisture capacity. A novel in situ respiration analysis technique was developed using a custom fabricated dry well and an in-line O2, CO2, CH4 analyzer to evaluate aerobic biological activity. Before and after treatment leachability analyses were conducted using the Sequential Batch Leachate Test (SBLT) and the Synthetic Precipitate Leaching Procedure (SPLP) to evaluate the groundwater implications of the underlying aquifer when the treated material is placed back onsite. Using a zero-order degradation model, contaminant analysis indicated that BaP treatement goals could be met in 9.6 years for LTU 1 and 2.7 years for LTU 2. PCP was not degraded appreciably in either LTU. Respiration analysis, coupled with statistically significant reduction in heavy PAHs (4-, 5-, and 6-ring), demonstrated significant biological activity even at the unusually high contaminant concentrations observed. PLFA analysis showed continuous increase in biomass and divergence of community composition between LTU 1 and LTU 2. LTU 2 showed an increase in the relative percentage of gram negative bacteria. Pre- and post-leachability analysis indicates that the treated material will not serve as a source of groundwater contamination if placed back onsite.
Appears in Collections:Technical Report

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