Technology Status Report: In Situ Flushing - CLU-IN

In Situ Flushing Project Summaries
GWRTAC Case Study Database
GWRTAC ID: FLSH0058
Project Name: Hialeah County, FL
City: State/Province: FL
Primary GWRTAC Personal
Communication Source
(Name/Organization):
Project Summary:
None
None
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 quoted from Rice University, 1997: Technology Practices Manual for
Surfactants and Cosolvents, Rice University, 6100 Main Street, Houston, TX 77005-1892, February
1997:
"In 1988, a combination of alkali and polymer was used to recover hydraulic oil present in
limestone beneath a commercial facility in Hialeah County, Florida (Pouska, et al., 1989). The
hydraulic oil had a density of 0.915 g/crn3 and a viscosity of 130 centipoise. An estimated 35,000
gallons of hydraulic oil was present beneath an area of 40,000 ft2. Free product thickness in wells
was observed at thicknesses ranging from 0.01 to 1.5 ft. Average depth to the contamination was 7
ft. Average oil saturation in the free oil layer was 65 percent of the pore space, while oil saturation
in areas having only adsorbed oil averaged 35 percent or less. Injection of water left a residual oil
saturation of 20 percent, which resulted in an evaluation of enhanced recovery methods.
The site geology is complex, consisting of a solution cavity limestone that exhibits a number of
depression features. These depression features are in-filled with a clay and organic-rich sand. The
limestone mounds were determined to be the main conduits of oil because the hydraulic
conductivity of the limestone (1,000 ft/day) was 1 to 2 orders of magnitude greater than the clay
and organic-rich sand.
A laboratory program was performed to define the optimum chemical system to remove residual
oil. A mobilization mechanism was selected. Interfacial tensions were lowered to ultra low values
with either alkali or alkali plus surfactant addition to injection water. In situ components in the oil
reacted with the alkali to develop surfactants which lowered the interfacial tension. The solution
selected for injection was 0.5 wt% Na2 CO3 plus 1.1 wt% NaHCO3, plus 0.5 wt% Na2 O(Si02
)3.22, plus 0.01 wt% Chloramine T plus 1000 mg/L xanthan gum. Xanthan gum polymer was
added to the injected solution to improve contact and displacement efficiencies. Because of the
high hydraulic oil viscosity, the mobility ratio for water displacing hydraulic oil was adverse
indicating a need for polymer.
The pilot was confined in a 10-foot by 10-foot area. A 10-foot slotted lateral delivery drainline
bisected the pilot area at a depth of 4 feet. The drainline was placed 5 feet from four vertical
production wells, which were situated at the four corners of the pilot area. Vertical production wells
Ground-Water Remediation Technologies Analysis Center
Operated by Concurrent Technologies Corporation
Appendix - Page 117 of 164
Copyright GWRTAC 1998
Revision 1
Tuesday, November 17, 1998