¹U.S. Environmental Protection Agency Region 10, Oregon Operations Office, 811 SW 6th Avenue, Portland, OR 97204, 503-326-3689; ²U.S. Army Environmental Center, Aberdeen Proving Ground, MD, 21010-5401, 410-612-6851; ³Seattle District Corps of Engineers, 4735 E. Marginal Way S., Seattle, WA, 98124-2255, 206-764-3458; and 4Oregon Department of Environmental Quality, Waste Management and Cleanup Division, 811 SW 6th Avenue, Portland, OR, 97204, 503-229-6530
The investigation of past operational and disposal practices at federal facilities and formerly used defense sites (FUDS) has dramatically increased in the past several years. The manufacture; load, assembly and pack (LAP); demilitarization; washout operations; and open burn/open detonation (OB/OD) of ordnance and explosives has resulted in contamination of soils with munitions residues. The primary constituents are nitroaromatic and nitramine organic compounds and heavy metals. A number of sites have soil contamination remaining where waste disposal practices were discontinued 20 to 50 years ago.
In conjunction with site investigations, biological treatment studies have been undertaken to evaluate the potential for full scale remediation of organic contaminants. This paper evaluates the results of 15 bioremediation treatability studies conducted at eight sites for explosives-contaminated soils, and discusses the full scale remedial implementation status. Five types of biological treatment processes have been evaluated: (1) composting, (2) anaerobic bioslurry, (3) aerobic bioslurry, (4) white rot fungus treatment and (5) landfarming. Representative bench and pilot scale studies were conducted using site-specific munitions residues to determine the ability to meet preliminary remediation goals (PRGs) or cleanup levels, and to identify issues related to scale-up of the technologies.
Composting has been selected as the full scale remedial action treatment remedy at two National Priority List (NPL) sites: (1) Umatilla Army Depot Activity, Hermiston, Oregon, for 14,800 tons of soil contaminated with TNT (2,4,6-trinitrotoluene), RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) and HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine), and (2) U.S. Naval Submarine Base, Bangor, Washington, for 2,200 tons of TNT-contaminated soils. Pilot scale composting treatability studies have demonstrated the ability to achieve risk-based cleanup levels of 30 to 33 parts per million (ppm) for TNT and 9 to 30 ppm for RDX after 40 days of treatment, with a destruction and removal efficiency (DRE) of greater than 99.0%. Feasibility Study (FS) estimates of treatment costs range from $206 to $766 per ton for quantities of 1,200 to 30,000 tons40% to 50% less than on-site incineration. In the past, all NPL sites with explosives contamination have used incineration as the selected treatment technology. Actual costs for biotreatment will be refined during full scale remediation.
explosives, munitions, ordnance, bioremediation, biological treatment
This paper is from the Proceedings of the 10th Annual Conference on Hazardous Waste Research 1995, published in hard copy and on the Web by the Great Plains/Rocky Mountain Hazardous Substance Research Center.
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