- Four treatment beds (housed in a temporary tent); soil pretreated using a 0.25-inch vibrating screen
- Total of four treatment series - each series involved the four treatment beds used concurrently to test different combinations of enhancements (UV oxidation, peroxide addition, and ethanol addition) and bioremediation (nutrient addition)
- Mixing rate - weekly during treatment series 1; beds changed once every 84 days
- Residence time - average of 84 days
- Depths of lifts - 6 to 12 inches
- ROD signed: May 6, 1993
|EPA Remedial Project Manager:|
U.S. EPA Region 10
1200 6th Avenue
Seattle, WA 98101
Dr. Benjamin J. Mason
Electric Power Research Institute
9671 Monument Drive
Grants Pass, OR 97526-8782
BPA Ross Complex
5411 Northeast Highway 99
Vancouver, WA 98663
High molecular weight polycyclic aromatic hydrocarbons (HPAHs) and pentachlorophenol (PCP)
- HPAHs in soils during RI at levels up to 150 mg/kg (1,500 mg/kg in hot spots)
- PCP in soils during RI at levels up to 62 mg/kg (5,00 mg/kg in hot spots)
Drips and spills from wood preserving operations
Type/Quantity of Media Treated:
Soil - 2,300 cubic yards
Purpose/Significance of Application:
Combination of bioremediation and enhancements used to land treat contaminated soil
Regulatory Requirements/Cleanup Goals:
- The ROD specified primary target goals of 1 mg/kg for HPAH and 8 mg/kg for PCP.
- Because of concern about the ability to achieve the primary goal, the ROD included three alternatives (tiers) of cleanup goals. Tier 1: Enhanced land treatment - 1 mg/kg for HPAH; 8 mg/kg for PCP; Tier 2: Enhanced land treatment with installation of gravel cap on soil and institutional controls - 23 mg/kg for HPAH; 126 mg/kg for PCP; and Tier 3: Enhanced land treatment, with installation of multilayered cap on soil and institutional controls, greater than 23 mg/kg HPAH, greater than 126 mg/kg PCP.
- HPAH and PCP levels in soil were reduced by approximately 80 percent after treatment, and all soils met Tier 2 levels, at a minimum.
- Concentrations for the four treatment series ranged from 6.76 to 21.83 mg/kg for HPAHs and from 6.8 to 20.7 mg/kg for PCP.
- EPRI concluded that land treatment could not meet Tier 1 cleanup goals for all soil at the site.
- Actual total cost of the project through November 1995 - $1,082,859 ($532,859 paid by BPA and $550,000 paid by EPRI). Includes costs for excavation, capital equipment, and operation and maintenance (O&M). Does not include cost for a gravel cap that was not completed until January 1996.
The total cost of $1,082,859 corresponds to a unit cost of $470 per yd3 for 2,300 yd3 of soil treated.
The Bonneville Power Administration (BPA) owns and operates a power distribution center in Vancouver, Washington, known as the Ross Complex. The site, an active facility that BPA has operated since 1939 to distribute hydroelectric power throughout the Pacific Northwest, also has been used for research and testing, maintenance construction operations, and storage and handling of hazardous and nonhazardous waste. Operable Unit A (OU A) at the Ross complex consists of 21 contaminated areas, including the Wood Pole Storage Area. The Wood Pole Storage Area had been used to dry transmission line poles treated off site with pentachlorophenol (PCP) and creosote. The treated poles were transported to the site and placed on cross poles to dry. Contamination occurred when chemicals dripped from the poles onto the ground. A remedial investigation (RI) identified HPAHs (the sum of eight carcinogenic polycyclic aromatic hydrocarbons found in creosote) and PCP as the contaminants of concern. Under a ROD signed May 6, 1993, land treatment was selected as the remedy for the Wood Pole Storage Area. EPRI agreed to split the cost of the remediation in exchange for use of the project as a research tool to evaluate the rates of degradation under various bioremediation enhancement techniques.
The land treatment system consisted of a temporary treatment tent that housed four treatment beds. Contaminated soil first was passed through a 0.25-inch vibrating screen and then was placed in a treatment bed. Four treatment beds were used to concurrently test different bioremediation enhancement techniques including UV oxidation, peroxide addition, and ethanol addition, well as biodegradation (nutrient addition). Several combinations (configurations) of enhancements and biodegradation with nutrient addition were tested with the four test beds operated concurrently over a total of four different treatment series. All soils met Tier 2 levels; however, EPRI concluded that land treatment could not meet Tier 1 cleanup goals for all soil at the site. For this application, the performance of bioremediation with nutrient addition was found to be comparable to land treatment enhanced with hydrogen peroxide, ethanol, or UV light or with combinations of these enhancements. EPRI identified factors that could improve performance of UV-enhanced bioremediation for future applications, including: (1) using a higher-intensity UV light, (2) mixing soil more frequently, and (3) increasing the dissolution of contaminants to increase exposure to the UV rays. Initially, the nutrient solution was based on Alaska fish meal. However, test results showed that the microorganisms consumed the fish meal but did not degrade the contaminants of concern. A change was made to a new nutrient solution based of Miracle Gro, a fertilizer containing nitrogen. EPRI noted that results improved when a relatively large volume of nutrient solution was maintained in the soils and that the treatment efficiency was relatively consistent throughout the year, independent of ambient temperature and precipitation.