Technology Status Report: In Situ Flushing - CLU-IN

In Situ Flushing Project Summaries
GWRTAC Case Study Database
GWRTAC ID: FLSH0054
Project Name: U.S. DOE Gaseous Diffusion Plnt, Paducah, KY
City: Paducah State/Province: KY
Primary GWRTAC Personal
Communication Source
(Name/Organization):
Project Summary:
Jacqui Avvoukomides
Duke Engineering & Services
Report(s)/Publication(s) (GWRTAC Source):
Rice University, 1997: Technology Practices Manual for Surfactants and Cosolvents, Rice
University, 6100 Main Street, Houston, TX 77005-1892, February 1997
The following was excepted from Rice University, 1997: Technology Practices Manual for
Surfactants and Cosolvents, Rice University, 6100 Main Street, Houston, TX 77005-1892, February
1997:
In 1994, a single-well surfactant injection-withdrawal field pilot test was conducted at the U.S.
Department of Energy Paducah Gaseous Diffusion Plant (PGDP) located in Paducah, Kentucky
(Intera, 1995). The test was completed in an alluvial aquifer located 20 to 30 m beneath a vapor
degreasing facility located within Waste Management Unit 11 (WMU-11). It is estimated that
10,000 gallons of trichloroethylene (TCE) may have leaked from the degreasing facility to the
subsurface. The aquifer beneath the facility is characterized as a gravely, fine to medium sand
having a hydraulic conductivity of approximately 3 x 10-3 cm/s. TCE concentrations in sampled
groundwater in the vicinity of the test site varied up to approximately 10 percent of the aqueous
solubility of TCE, suggesting that immiscible-phase TCE may be present in the subsurface.
Immiscible-phase TCE has not been observed in monitoring wells at the site.
A total of 99 surfactants (25 nonionics and 74 anionics) were screened to asses their ability to
solubilize TCE. The purpose of the surfactant injection was to solubilize TCE, not mobilize TCE.
The screening procedure consisted of stirring TCE-surfactant mixtures for a minimum of 24 hours,
followed be centrifugation at 3,500 rpm for 1 hour and gas chromatography (GC) analysis. A total
of 10 of the 99 surfactants (5 nonionics and 5 anionics) solubilized TCE to concentrations greater
than 15,000 ppm, representing a factor of approximately 13 increase in aqueous solubility. The
final surfactant selected was a sorbitan monooleate, capable of solubilizing TCE to approximately
16,000 mg/L using a 1 percent micellar-surfactant solution. The sorbitan monooleate is approved
for use as a food-grade additive by the U.S. Food and Drug Administration. The critical micelie
concentration (CMC) of this surfactant is reported to be 0.012 percent (by volume).
Prior to initiation of the field test, an assessment of vertical DNAPL mobilization was carried out.
The interfacial tension between TCE and a 1 percent surfactant solution was measured to be 11.7
dynes/cm, indicating that a lowering of interfacial tension does occur upon exposure to the selected
surfactant. It is not clear what equilibration time was used ' prior to conducting the interfacial
tension measurements. As a result, it is not clear whether or not the minimum interfacial tension
was measured given the exposure time expected for the field test. The mobility of residual DNAPL
Ground-Water Remediation Technologies Analysis Center
Operated by Concurrent Technologies Corporation
Appendix - Page 109 of 164
Copyright GWRTAC 1998
Revision 1
Tuesday, November 17, 1998