Rate of Contamination Removal of Two Phyto-remediation Sites at the DOE Portsmouth Gaseous Diffusion Plant
- CDM Federal Services, P.O. Box 789, Piketon, OH 45661 (United States)
This paper describes applications of phyto-remediation at the Portsmouth Gaseous Diffusion Plant (PORTS), a Department of Energy (DOE) Facility that enriched uranium from the early 1950's until 2000. Phyto-remediation has been implemented to assist in the removal of TCE (trichloroethylene) in the groundwater at two locations at the PORTS facility: the X-740 area and the X-749/X-120 area. Phyto-remediation technology is based on the ability of certain plants species (in this case hybrid poplar trees) and their associated rhizo-spheric microorganisms to remove, degrade, or contain chemical contaminants located in the soil, sediment, surface water, groundwater, and possibly even the atmosphere. Phyto-remediation technology is a promising clean-up solution for a wide variety of pollutants and sites. Mature trees, such as the hybrid poplar, can consume up to 3,000 gallons of groundwater per acre per day. Organic compounds are captured in the trees' root systems. These organic compounds are degraded by ultraviolet light as they are transpired along with the water vapor through the leaves of the trees. The phyto-remediation system at the X-740 area encompasses 766 one-year old hybrid poplar trees (Populus nigra x nigra, Populus nigra x maximowiczii, and Populus deltoides x nigra) that were planted 10 feet apart in rows 10 feet to 20 feet apart, over an area of 2.6 acres. The system was installed to manage the VOC contaminant plume. At the X749/X-120 area, a phyto-remediation system of 2,640 hybrid poplar trees (Populus nigra x maximowiczii) was planted in seven areas/zones to manage the VOC contaminant plume. The objectives of these systems are to remove contamination from the groundwater and to prevent further migration of contaminants. The goal of these remediation procedures is to achieve completely mature and functional phyto-remediation systems within two years of the initial planting of the hybrid poplar trees at each planting location. There is a direct relationship between plant transpiration, soil moisture, and groundwater flow in a phyto-remediation system. The existing monitoring program was expanded in 2004 in order to evaluate the interactions among these processes. The purpose of this monitoring program was to determine the rate of contaminant removal and to more accurately predict the amount of time needed to remediate the contaminated groundwater. Initial planting occurred in 1999 at the X-740 area, with additional replanting in 2001 and 2002. In 2003, coring of selected trees and chemical analyses illustrated the presence of TCE; however, little impact was observed in groundwater levels, analytical monitoring, and periodic tree diameter monitoring at the X-740 area. To provide better understanding of how these phyto-remediation systems work, a portable weather station was installed at the X-740 area to provide data for estimating transpiration and two different systems for measuring sap flow and sap velocity were outfitted to numerous trees. After evaluating and refining the groundwater flow and contaminant transport models, the data gathered by these two inventive methods can be used to establish a rate of contaminant removal and to better predict the time required in order to meet remediation goals for the phyto-remediation systems located at the PORTS site. (authors)
- Research Organization:
- WM Symposia, Inc., PO Box 13023, Tucson, AZ, 85732-3023 (United States)
- OSTI ID:
- 21208613
- Report Number(s):
- INIS-US-09-WM-06110; TRN: US09V0924079400
- Resource Relation:
- Conference: Waste Management 2006 Symposium - WM'06 - Global Accomplishments in Environmental and Radioactive Waste Management: Education and Opportunity for the Next Generation of Waste Management Professionals, Tucson, AZ (United States), 26 Feb - 2 Mar 2006; Other Information: Country of input: France; 6 refs
- Country of Publication:
- United States
- Language:
- English
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