Technology:
CROW™ process
- Hot water injected into subsurface; water and coal tar extracted and treated using a tar-water separator
- Six injection wells and two production wells (used for extraction)
- Water from separator treated using carbon adsorption; recovered tar sent off site for treatment
- Injection pressure - 20 psig
- Extraction rate - design of 100 gpm; actual of 40 gpm
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Cleanup Authority:
CERCLA
- ROD date: 3/29/91
- ESD date: 7/19/94
EPA Remedial Project Manager:
John Banks
U.S. EPA Region 3
841 Chestnut Street
Philadelphia, PA 19107
(215) 566-3214 | PRP Lead:
Jim Villaume
Senior Project Manager
Pennsylvania Power and Light (PP&L)
Two North Ninth Street
Allentown, PA 18101
(610) 774-5094 |
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Contaminants:
Coal tar and coal tar residual containing:
- PAHs - benzo(a)pyrene and naphthalene
- Nonhalogenated semivolatile organic compounds (SVOCs)
- Volatile organic compounds (VOCs) - benzene
- Metals - arsenic |
Waste Source:
Disposal of waste in open pit |
Type/Quantity of Media Treated:
Free product (coal tar) - 1,500 gallons of coal tar |
Purpose/Significance of Application:
Recover free and residual coal tar using the CROW™ process |
Regulatory Requirements/Cleanup Goals:
- The ROD specified removal of 60 percent of the total free-phase coal tar from the subsurface soils. However, the results of the preremedial design investigation found that an accurate measurement of the amount of free-phase coal tar was not possible.
- An ESD was issued to change the standard. The system was required to operate until the amount of free-phase coal tar recovered was minimal. |
Results:
- Initial estimate of total volume of coal tar removed - 1,500 gallons (based on estimate of amount removed for each pore volume of water flushed through the recovery zone). In addition, no measurable material had been recovered during the last three months of operation.
- However, EPA determined that the method used for this estimate was inaccurate and therefore could not be used to determine whether the performance standard had been met. In response, the PRPs were required to collect three additional pore volumes and perform quantitative analyses per EPA requirements.
- The results showed that the recovered process water did not contain free or separable coal tar; EPA agreed that the performance standard had been met and allowed the system to be shut down. |
Cost Factors:
- Total cost - $1.9 million, including $1.2 million for treatment costs.
- Costs for this application were shared among DOE, the Gas Research Institute, and PP&L. |
Description:
Citizen Gas and Electric operated a coal gasification plant at this site from 1888 until 1944. Coal tar from these operations was disposed of in open pits at the site. In October 1980, coal tar was observed to be seeping into Brodhead Creek. In December 1982, the site was placed on the National Priorities List. The results of the Remedial Investigation identified free-phase coal tar at the site. In addition, the soil and groundwater at the site were contaminated with PAHs, other SVOCs, VOCs, and metals. The ROD signed in 1991 specified the use of an enhanced recovery technology to remove free-phase coal tar from subsurface soils. The Contained Recovery of Oily Waste (CROW)™ process was selected for use at the site.
The CROW™ process involved injecting hot water into the subsurface through six wells to decrease the viscosity of the coal tar and facilitate recovery, then extracting the water and coal tar using two production wells. The extracted water and coal tar were treated using a tar-water separator. Water from the separator was treated using carbon adsorption; recovered tar was sent off site for treatment. While the design called for the system to be operated at a rate of 100 gpm, the actual rate was 40 gpm. A reason for the reduced rate included iron fouling problems in the well screens. Initial results indicated that the CROW™ process had removed 1,500 gallons of coal tar and that no measurable coal tar had been recovered during the last three months of operation. In March 1996, samples of the recovered material were taken from the storage tank. The results indicated that the contents were primarily water, and raised concerns about the method that was being used to calculate the volume of tar recovered. EPA determined that the method was not accurate, and therefore could not be used to determine whether the performance standard had been met. Additional pore volumes were collected and the results of quantitative analyses performed per EPA requirements showed that the cleanup goals had been met. |
