COST AND PERFORMANCE
REPORT FOR LNAPL CHARACTERIZATION
AND REMEDIATION
Partition Interwell Tracer Testing (PITT) and Rapid Optical Screening
Tool (ROST™) Characterization and Evaluation of the Feasibility of
Surfactant Enhanced Aquifer Remediation (SEAR)
at the Chevron Cincinnati Facility, Hooven, OH
February 2005
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Office of Solid Waste EPA 542-R-05-017
and Emergency Response February 2005
(5102G) www.epa.gov/tio
Cost and Performance Report for LNAPL
Characterization and Remediation
Partition Interwell Tracer Testing (PITT) and Rapid Optical
Screening Tool (ROST™) Characterization and Evaluation of the
Feasibility of Surfactant Enhanced Aquifer Remediation (SEAR) at
the Chevron Cincinnati Facility, Hooven, OH
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DISCLAIMER
This case study represents the views and opinions of the authors and those who participated in its
development. It has been subjected to U.S. Environmental Protection Agency (EPA) expert review,
however it does not necessarily reflect the views of the EPA or any other federal government
agency. The information is not intended, nor can it be relied upon, to create any rights enforceable by any
party in litigation with the United States or any other party. Reference herein to any specific commercial
product, process, or service by trade name, trademark, manufacturer, or otherwise does not imply its
endorsement or recommendation for use. The information provided maybe revised periodically without
public notice.
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Chevron Cincinnati Facility, Hooven, OH
CONTENTS
Section Page
EXECUTIVE SUMMARY 1
1.0 INTRODUCTION 3
2.0 SITE INFORMATION 3
2.1 IDENTIFYING INFORMATION 3
2.2 TECHNOLOGY APPLICATION 4
2.3 BACKGROUND 4
2.4 TIME LINE OF SITE ACTIVITIES 6
3.0 MATRIX AND CONTAMINANT DESCRIPTION 9
3.1 SITE GEOLOGY/STRATIGRAPHY 9
3.2 NATURE AND EXTENT OF CONTAMINATION 9
3.3 MATRIX DESCRIPTION AND CHARACTERISTICS 13
4.0 PERFORMANCE OBJECTIVES 14
5.0 TECHNOLOGY DESCRIPTION AND EVALUATION 15
5.1 PILOT-SCALE SITE CHARACTERIZATION STUDIES 15
5.1.1 PITT Pilot Test 15
5.1.2 CPT/ROST™ Pilot Test 17
5.2 ADDITIONAL BENCH-SCALE STUDIES 18
5.2.1 LNAPL Characterization Bench Study 18
5.2.2 Film Drainage and Wettability Characterization Bench Study 19
5.2.3 Phase Behavior Testing of Surfactants Bench Study 19
5.3 DESCRIPTION OF SEAR TECHNOLOGY 20
5.4 CMS EVALUATION OF SEAR TECHNOLOGY 23
6.0 OBSERVATIONS AND LESSONS LEARNED 26
7.0 SITE CONTACTS 29
8.0 REFERENCES 30
9.0 ACKNOWLEDGMENTS 30
U.S. Environmental Protection Agency i February 2005
Office of Solid Waste and Emergency Response
Office of Superfund Remediation and Technology Innovation
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Chevron Cincinnati Facility, Hooven, OH
FIGURES
Figure Page
1. Site Layout (with closeup of PITT Test Site Location), Chevron Cincinnati Facility, Hooven, OH 7
2. Facility Map, Chevron Cincinnati Facility, Hooven, OH 8
3. LNAPL at Typical Low Water Table Conditions, Chevron Cincinnati Facility, Hooven, OH 11
4. Schematic of a Partitioning Interwell Tracer Test 16
5. Conceptual Model of Surfactant Enhanced Aguifer Remediation 21
TABLES
Table Page
1. Properties of LNAPL at the Chevron Cincinnati Facility, Hooven, OH 10
2. Contaminants of Potential Concern (COPC) in Groundwater at the Chevron Cincinnati Facility, Hooven,
OH 12
3. Matrix Characteristics Expected to Affect Technology Cost or Performance at the Chevron Cincinnati
Facility, Hooven, OH 13
4. Surfactants Tested in Phase Behavior Experiments 20
U.S. Environmental Protection Agency ii February 2005
Office of Solid Waste and Emergency Response
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Chevron Cincinnati Facility, Hooven, OH
ABBREVIATIONS AND ACRONYMS
AOC Area of concern
BTEX Benzene, toluene, ethylbenzene, and xylene
bgs below ground surface
CMS Corrective measures study
COPC Contaminants of potential concern
CRT Cone penetrometer
cm centimeter
cm/s centimeters per second
DEHP Di(2-ethylhexyl) phthalate
EPA U.S. Environmental Protection Agency
GWCMS Groundwater corrective measures study
g/cm3 grams per cubic centimeter
LNAPL Light non-aqueous phase liquid
MCL Maximum contaminant level
MNA Monitored natural attenuation
MPPE Macroporous polymer extraction
MW Molecular weight
mg/L milligrams per liter
mm millimeter
mS /cm millisiemens per centimeter
mV millivolts
PITT Partitioning inter-well tracer test
PRG Preliminary remediation goal
P&T Pump and treat
RCRA Resource Conservation and Recovery Act
ROST™ Rapid optical screening tool
SEAR Surfactant-enhanced aquifer remediation
SVE Soil vapor extraction
SWMU Solid waste management unit
LIST Underground storage tank
Mg/L micrograms per liter
wt % percent by weight
U.S. Environmental Protection Agency iii
Office of Solid Waste and Emergency Response
Office of Superfund Remediation and Technology Innovation
February 2005
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Chevron Cincinnati Facility, Hooven, OH
EXECUTIVE SUMMARY [1,2,3,4,5,6]
Light non-aqueous phase liquid (LNAPL) represents a continuing source of groundwater contamination
and may extend the required time for site remediation by years to decades. This case study summarizes
the characterization studies and technology evaluation of surfactant enhanced aquifer remediation (SEAR)
conducted for LNAPL at the Chevron Cincinnati Facility in Hooven, OH. This report summarizes the
evaluation of the use of SEAR as a potential innovative and aggressive technology to treat LNAPL at this
site.
Site characterization using a partitioning inter-well tracer test (PITT) and cone penetrometer with rapid
optical screening tool (CPT/ROST™) was performed to further define the LNAPL contamination and to
provide information about the potential applicability of SEAR at this site. The characterization studies
identified typical residual LNAPL saturation within the smear zone ranging from 1 to 8% of the soil pore
volume. The highest LNAPL saturations were observed in zones of mobile LNAPL during times of low
water table levels. Based on the characterization and treatability testing described in this report, it was
determined that SEAR could potentially reduce the LNAPL saturation to less than 1%. The specific goal
for the SEAR system was to reduce the LNAPL to levels where SEAR can no longer mobilize the LNAPL,
determined to be between 0.5% and 1%. If reduced to this level, the LNAPL was expected to remain
immobile after the completion of the SEAR. The studies also found that a mixture including proprietary
anionic and catonic surfactants would be the optimal formulation for this site.
The draft Corrective Measures Study (CMS) [1] identified the time to reach final cleanup goals, present
value cost, and compatibility with site redevelopment for the SEAR system. The preliminary cleanup goal
used as a basis to select the remedy was a benzene concentration in groundwater below the drinking
water maximum contaminant level (MCL) of 5 pg/L. It was estimated that SEAR operations, in conjunction
with soil vapor extraction (SVE), would take from 8 to 12 years. However, application of these
technologies would not achieve final cleanup goals, and would need to be followed by hydraulic
containment and monitored natural attenuation (MNA), which would need about 100 years to reach
cleanup goals. Uncertainty in the volume of LNAPL at the site precluded more refined estimates. The
CMS recommended hydraulic containment as a remedy because using any of the remedial options
considered, including the SEAR technology, it was "not possible to return the aquifer to its maximum
beneficial use in a reasonable time period." Although the CMS did not define a reasonable time period, it
did note that all of the remedial options considered required 100 years or more.
The evaluation of SEAR at this site resulted in observations and lessons learned that may be helpful when
this technology is evaluated for other sites. It was assumed that the extracted LNAPL and groundwater
emulsion could be treated using aboveground technologies to recover LNAPL and reduce contaminants
prior to reinjection. However, the feasibility of the aboveground treatment has not been proven. Based on
U.S. Environmental Protection Agency 1 February 2005
Office of Solid Waste and Emergency Response
Office of Superfund Remediation and Technology Innovation
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Chevron Cincinnati Facility, Hooven, OH
the size of the LNAPL plume at this site, the SEAR system was estimated to be two orders of magnitude
larger than the largest SEAR operation conducted through October, 2001, which was when the
technology evaluation was completed. The CMS stated that substantial technology development would
be required to bridge this experience gap.
U.S. Environmental Protection Agency 2 February 2005
Office of Solid Waste and Emergency Response
Office of Superfund Remediation and Technology Innovation
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Chevron Cincinnati Facility, Hooven, OH
1.0 INTRODUCTION
This case study summarizes the results of an evaluation of the applicability of surfactant-enhanced aquifer
remediation (SEAR) to treat LNAPL contamination at the Chevron Cincinnati Facility in Hooven, OH.
Remediation of LNAPL in contaminated media is a particularly challenging problem. LNAPLs usually
consist of volatile organic compounds such as benzene, toluene, ethylbenzene, and xylene (BTEX).
When released into the subsurface, they become intermixed with the soil matrix and groundwater, and are
held in the soil by capillary forces. The LNAPL continues to release dissolved contaminants to
surrounding media for an extended period of time. As the water table changes in depth overtime, the
LNAPL also rises and falls, creating a contaminant "smear zone" that is difficult to treat. No single
technology has been identified as the best solution for all sites contaminated with LNAPLs. The most
commonly used groundwater treatment technology, pump-and-treat (P&T), requires very long treatment
times to reach cleanup goals and restore contaminated aquifers when LNAPLs are present.
In some cases, innovative technologies may effectively treat LNAPLs, restore contaminated aquifers to
productive use more quickly than P&T, assist P&T in achieving cleanup, or reduce treatment costs.
However, such technologies might not be used if site managers are not aware of their capabilities, or
determine that their effectiveness has not been demonstrated. Additional information on the evaluation
and application of innovative technologies to treat LNAPLs is needed to promote their acceptance and use
as an alternative to P&T. This case study provides such additional information.
2.0 SITE INFORMATION
2.1 IDENTIFYING INFORMATION [1]
Site Name: Chevron Cincinnati Facility
Location: Hooven, Ohio
Regulatory Context: RCRA corrective action (Facility ID: OHD004254132)
Technology: Surfactant Enhanced Aquifer Remediation (SEAR)
Scale: Not applicable. Based on results of site characterization studies, SEAR was not tested at the site.
2.2 TECHNOLOGY APPLICATION [1,3]
Period of Operation: At the time of this report, SEAR had not been tested at the site; the
characterization studies used to evaluate the feasibility of SEAR at this site were
conducted in September 1999 (see Section 5.2).
Type/Quantity of Media Treated During Application: Not applicable
U.S. Environmental Protection Agency 3 February 2005
Office of Solid Waste and Emergency Response
Office of Superfund Remediation and Technology Innovation
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Chevron Cincinnati Facility, Hooven, OH
2.3 BACKGROUND [1,2]
The site is a former petroleum refinery owned by Chevron Products Company (Chevron) near Hooven in
Whitewater Township, Ohio, approximately 20 miles west of Cincinnati, Ohio. It occupies 600 acres along
the Great Miami River, which borders the site to the east, northeast, and southeast. The town of Hooven
borders the site to the west. Refinery operations occurred on approximately 250 acres containing the
plant process areas, storage tanks, and other facilities. The remainder of the site consists of tracts of
upland and bottomland forests, open brushy areas, and isolated wetlands, which served as a buffer zone
along the river. The general layout while the site was in operation is shown on Figure 1, which is based on
areal photographs from about 1962.
The refinery was constructed in 1931 and operated until May 1986. Major products produced at the
refinery were gasoline, jet fuel, diesel, heating fuel, liquefied petroleum gas, asphalt, and sulfur.
Accidental spills, pipeline failures, and tank leaks during historical operations at the site released an
estimated 7 million gallons of LNAPL to the aquifer. Decommissioning, dismantling, and environmental
remediation have been underway since May 1986. As of 2001, nearly all of the above-ground buildings
and structures had been razed.
Interim actions began in the mid-1980s when a hydrocarbon sheen was observed seeping into the Great
Miami River. A groundwater P&T system was installed to hydraulically contain the hydrocarbon plume.
The system extracts groundwater through a series of 14 wells and treats it using an aerobic, fluidized bed
bio-reactor to remove organic contaminants. The effluent from the bioreactor is further treated in lagoons
to remove suspended solids before it is discharged to the river. The system pumps and treats 4 to 5
million gallons of groundwater on a seasonal basis. During low water-table periods, wells are pumped to
create cones of depression, which allow LNAPL to be pumped. The LNAPL is recovered by skimming it
from recovery wells and pumping it to storage prior to off-site shipment. As of 2000, approximately 3.5
million gallons of LNAPL have been recovered. At that time, about 8 million gallons of DNAPL was
believed to remain in situ, however, more recent estimates indicate that only 3.5 million gallons of DNAPL
remain. Groundwater monitoring is ongoing to verify hydraulic containment.
In 1995, soil vapor extraction (SVE) began seasonal operations to address hydrocarbon contamination in
the vadose zone at Islands No. 1 and 2 (see Figure 2). The SVE system uses a thermal oxidizerto treat
off-gas. Through 2000, air stripping removed approximately 21,000 pounds of hydrocarbons and
biodegradation removed another 7,500 pounds. Since 2000, this system has been switched to bioventing
with limited SVE. A more detailed description of the SVE and bioventing systems was not available in the
references used for this report. In addition, a second SVE system consisting of three horizontal wells is
being used to address LNAPL that has migrated off-site under the eastern half of Hooven. Horizontal
U.S. Environmental Protection Agency 4 February 2005
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Chevron Cincinnati Facility, Hooven, OH
wells are being used to minimize off-site construction. This system began operation in 1999 and operates
intermittently depending on the height of the water table.
In 1993, Chevron entered into an Administrative Order with EPA Region 5 to perform a RCRA Facility
Investigation (RFI) to identify the nature and extent of contamination at the site and a Corrective Measures
Study (CMS) to evaluate long-term corrective actions. Phase 1 of the RFI investigated the perimeter of
the site to evaluate the extent of possible off-site contamination, while Phase 2 addressed surficial areas
and groundwater located within the site. Phase 2 also included a facility-wide risk assessment. The RFI
was completed and approved by EPA in 2000.
The RFI identified soil and sediment contamination, as well as both LNAPL and dissolved contamination in
groundwater. Several high priority solid waste management units (SWMUs) and areas of concern (AOCs)
were identified based on risks to human health and the environment and compatibility with anticipated
future land use. These SWMUs and AOCs were remediated. With EPA's concurrence, Chevron decided
to address soil, sludge and groundwater under a separate CMS. In October 2002, Chevron submitted the
soil and sludge CMS and, in June 2003, EPA published a Statement of Basis for Sludges and
Contaminated Soil that specified excavation and off-site disposal in a RCRA hazardous waste landfill as
the proposed remedial alternative.
As of June, 2004, the groundwater CMS was not yet final. The CMS evaluated the following alternatives
considered for addressing LNAPL-contamination at this site:
Hydraulic containment
Surfactant enhanced aquifer remediation (SEAR)
In situ air sparging
Soil vapor extraction (SVE)
In situ chemical treatment
Thermal enhancements of SVE, including six-phase heating, steam injection, and hot air injection
Groundwater circulating wells
Monitored natural attenuation
Institutional controls
As of June, 2004, a final groundwater remedial alternative was not yet implemented. This report provides
a description of the SEAR remediation system that was evaluated for this site. This report also includes
the bench- and pilot-scale site characterization studies that were used as the basis for the SEAR
evaluation. While no information was provided on the cost of the pilot-scale studies, a cost estimate for a
full-scale SEAR system was developed (see section 5.4).
U.S. Environmental Protection Agency 5 February 2005
Office of Solid Waste and Emergency Response
Office of Superfund Remediation and Technology Innovation
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Chevron Cincinnati Facility, Hooven, OH
2.4 TIME LINE OF SITE ACTIVITIES [3,4]
1931 Refinery constructed and operations begin
1986 Refinery operations shut down and site investigation and remediation
activities begin
1988 Hydraulic containment with P&T begins
1995 SVE system to remediate on-site contamination begins
July - September 1998 CPT/ROST™ pilot-scale site characterization conducted
August 16-17, 1998 PITT pilot-scale site characterization conducted
1999 Second SVE system constructed to remediate off-site contamination
September 1999 Additional bench-scale feasibility studies conducted
2000 On-site SVE replaced with bioventing and limited SVE
U.S. Environmental Protection Agency 6 February 2005
Office of Solid Waste and Emergency Response
Office of Superfund Remediation and Technology Innovation
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Chevron Cincinnati Facility, Hooven, OH
Figure 1. Site Layout (with closeup of PITT Test Site Location), Chevron Cincinnati Facility, Hooven, OH
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U.S. Environmental Protection Agency
Office of Solid Waste and Emergency Response
Office of Superfund Remediation and Technology Innovation
February 2005
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Chevron Cincinnati Facility, Hooven, OH
Source: Radian International and Duke Engineering Services, 1999
U.S. Environmental Protection Agency
Office of Solid Waste and Emergency Response
Office of Superfund Remediation and Technology Innovation
February 2005
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Chevron Cincinnati Facility, Hooven, OH
Figure 2. Facility Map, Chevron Cincinnati Facility, Hooven, OH
Source.
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Facility Diagram
CHEVROK PRODUCTS COMPANY
Figure 2-3
U.S. Environmental Protection Agency
Office of Solid Waste and Emergency Response
Office of Superfund Remediation and Technology Innovation
February 2005
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Chevron Cincinnati Facility, Hooven, OH
3.0 MATRIX AND CONTAMINANT DESCRIPTION
3.1 SITE GEOLOGY/STRATIGRAPHY [1,3]
The site lies in a valley cut into the shale bedrock by the ancestral Great Miami River and then partially
filled with glacial outwash. The shale bedrock has a low permeability, but contains fine cracks, joints, and
thin layers of interbedded limestone. The glacial outwash is composed of unconsolidated sand and
gravel, giving it a high permeability. Also, rapidly varying depositional conditions resulted in
heterogeneous conditions, especially in the upper part of the aquifer, where lower permeability alluvial silt
and sand cover the glacial outwash. Contractors at the site have categorized the site into the following
three stratigraphic layers:
Upper Zone (0 to 12 feet bgs) - Fine-grained alluvial deposits such as silts, clays, and some fine
sand
Transition Zone (12 to 22 feet bgs) - Gravely silts, fine sands, silty gravels, and small cobbles
intermixed in a silt or sandy silt matrix
Lower Zone (22 to 122 feet bgs) - Complex sequence of sands and sandy gravels
Under natural conditions, groundwater flow at the site is from north to south with discharge to the Great
Miami River. Currently, the groundwater flow system is controlled by groundwater extraction, causing
groundwater to flow from the facility boundary and the river to the extraction areas in the southern portion
of the site. Groundwater elevation at the site varies seasonally (typically by 2 to 5 feet, but by as much as
18 feet) as the river stage rises and falls throughout the year. Within the PITT test site area, the depth to
groundwater was measured between 17 and 32 feet bgs. The LNAPL extends from 12 to 30 feet bgs, and
is present primarily in the transition zone.
3.2 NATURE AND EXTENT OF CONTAMINATION [1,3,4]
Type of Media Treated With Technology System: LNAPL, soil, and groundwater (LNAPL smear zone)
Primary Contaminants at the Site:
Petroleum hydrocarbons, LNAPL (mixture of leaded gasoline, diesel fuel, and crude oil)
U.S. Environmental Protection Agency 10 February 2005
Office of Solid Waste and Emergency Response
Office of Superfund Remediation and Technology Innovation
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Chevron Cincinnati Facility, Hooven, OH
LNAPL at the site is typically a mixture of approximately 80% leaded gasoline and 20% diesel fuel, but its
composition across the site is a variable combination of gasoline, diesel, and crude oil. Generally, it can
be identified as one of two types:
Type 1 LNAPL - a low viscosity and low density LNAPL that underlies most of the facility and has
migrated off the site under Hooven; Type 1 is the LNAPL primarily present in the PITT Test Site
area. Based on the location where this type of LNAPL is found and its physical and chemical
characteristics, it is likely to have originated from gasoline and diesel fuel leaks and spills.
Type 2 LNAPL - a higher viscosity and higher density LNAPL containing heavier hydrocarbons
(with approximately half of the LNAPL heavier than C14); Type 2 LNAPL is present primarily on
the eastern edge of the facility. Based on the location where this type of LNAPL is found and its
physical and chemical characteristics, it is likely to have originated from a mixture of crude oil and
diesel fuel leaks and spills.
Table 1 summarizes selected properties of these two types of LNAPL.
Table 1. Properties of LNAPL at the Chevron Cincinnati Facility, Hooven, OH
Property
Density
Viscosity
Interfacial Tension
Benzene
Xylene
Compounds > C14
Type 1 LNAPL
<0.85 g/cm3
<2 centipoise
~24 dynes/cm
0.1 -0.45wt%
~5 wt %
~7 wt%
Type 2 LNAPL
>0.85 g/cm3
>5 centipoise
~12 dynes/cm
0 - 0.03 wt%
<0.8 wt %
-53 wt%
Source: Radian International and Duke Engineering & Services, 2000
Table 2 lists the contaminants of potential concern (COPC), the maximum concentration of each COPC
detected at the site, and the preliminary cleanup goals. The LNAPL is present in a smear zone extending
from approximately 12 to 30 feet bgs, which is primarily in the transition zone described in Section 3.1.
The area of LNAPL contamination is approximately 200 acres. At times of year when the groundwater
table is low (typically in winter), most of the smear zone is present above the water table. Figure 3 shows
the site at typical low water table conditions and includes the approximate extent of the free-phase LNAPL,
as well as LNAPL thickness. Free-phase LNAPL thickness ranges from 0.1 ft to 1.5 feet at some wells.
Approximately half of the plume has a free-phase LNAPL thickness less than 0.5 feet, while the other half
11
U.S. Environmental Protection Agency
Office of Solid Waste and Emergency Response
Office of Superfund Remediation and Technology Innovation
February 2005
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Chevron Cincinnati Facility, Hooven, OH
has a thickness greater than 0.5 feet. Additional figures showing LNAPL at typical high water table and
extreme low water table conditions are included in the GWCMS [1]. When the groundwater table is high
U.S. Environmental Protection Agency 12 February 2005
Office of Solid Waste and Emergency Response
Office of Superfund Remediation and Technology Innovation
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Chevron Cincinnati Facility, Hooven, OH
Figure 3. LNAPL at Typical Low Water Table Conditions, Chevron Cincinnati Facility, Hooven, OH
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Source: OWCffi*S-jr20m%ntal Protection Agency
Office of Solid Waste and Emergency Response
Office of Superfund Remediation and Technology Innovation
13
February 2005
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Chevron Cincinnati Facility, Hooven, OH
(typically in the spring), most of the LNAPL smear zone is submerged and, in some cases, no free-phase
layer is present.
Table 2. Contaminants of Potential Concern (COPC) in Groundwater
at the Chevron Cincinnati Facility, Hooven, OH
Contaminant of Potential Concern
Benzene
Ethylbenzene
1,4-Dichlorobenzene
Acetophenone
Di(2-ethylhexyl) phthalate (DEHP)
Naphthalene
Pyrene
Dissolved Lead
Total Arsenic
Maximum Concentration
Detected (ug/L)
5,000
2,000
440
21
46
450
630
39
81
Cleanup Goal
(ug/L) (Basis)
5 (MCL)
700 (MCL)
75 (MCL)
0.042 (PRG)
6 (MCL)
6.2 (PRG)
180 (PRG)
15 (MCL)
10 (MCL)
Cleanup Level Basis:
MCL - Federal Safe Drinking Water Act Maximum Contaminant Level
PRG - U.S. EPA Region 9 Preliminary Remediation Goal
Source: GWCMS, 2001
Most of the documents used as references for this report describe the distribution of the LNAPL in the
subsurface as following the "pancake" model, which is based primarily on the difference in density
between LNAPL and water, and the adsorption of LNAPL onto soil. In this model, LNAPL is believed to
float on top of the groundwater table. As the groundwater table fluctuates, the LNAPL layer rises and falls
with the groundwater, creating a "smear zone" of contamination where the LNAPL adsorbs to soil. The
LNAPL characterization and remedial design described in this report was based in part on this model of
LNAPL behavior.
Since the publication of those references, new research into the behavior of LNAPL indicates that it may
follow a model that is based on the capillary forces that soil exerts on water and LNAPL in addition to
density differences. In this model, LNAPL, water, and air exist in the subsurface in different zones. In the
deepest zone the soil pore space contains primarily water. Above this zone, capillary forces and density
differences create a mixture of water and LNAPL, rather than a zone of pure LNAPL, as in the "pancake"
model. Above this is a capillary fringe that includes a mixture of LNAPL, water, and air, above which is
the vadose zone. One of the practical implications of this model is that the LNAPL zone is believed to
contain significant amounts of water, rather than primarily LNAPL. Therefore, the total volume of LNAPL
estimated for an observed LNAPL thickness can be significantly less than the "pancake" model.
14
U.S. Environmental Protection Agency
Office of Solid Waste and Emergency Response
Office of Superfund Remediation and Technology Innovation
February 2005
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Chevron Cincinnati Facility, Hooven, OH
The characterization and design activities described in this report were conducted before the current
model was widely accepted, and were based, in part, on the "pancake" model. The effects of applying the
current model to the test results and design assumptions described here have not been assessed.
3.3 MATRIX DESCRIPTION AND CHARACTERISTICS [3,4]
Table 3 lists the matrix characteristics of the Chevron Cincinnati Facility within the PITT test site area,
which was conducted primarily in the transitional zone (see Section 3.1 for a description of the geologic
zones at the site).
Table 3. Matrix Characteristics Expected to Affect Technology Cost or Performance at the
Chevron Cincinnati Facility, Hooven, OH
Parameter
Soil classification
Clay content and/or particle
size distribution
Hydraulic conductivity
(horizontal)
Groundwater velocity
Permeability
PH
Depth of water table below
ground surface
Presence of NAPLs
Electrochemical potential (EH)
Electrical conductivity
Dissolved oxygen
Nitrate
Iron
Value
Alluvial silt and sand and unconsolidated sand
and gravel glacial outwash over shale bedrock
with interbedded limestone layers
5 - 15% less than 0.25 mm diameter (fine sand,
silt, clay)
40 - 80% greater than 2 mm diameter (gravel)
10"4- 10"2 cm/s (based on permeameter testing)
0.1 cm/sec (based on pumping tests)
2 - 4 feet per day
0.13- 12darcies
6.7-7.0
17-32feetbgs
LNAPL present (estimated 3.5% LNAPL
saturation from 22 - 32 feet bgs within the PITT
test site area)
130- 160 mV
520 - 1 ,070 mS-cm
0.02 - 0.09 mg/L
<0.5 mg/L
4 - > 1 0 mg/L
Source: Radian International and Duke Engineering & Services, 1999
15
U.S. Environmental Protection Agency
Office of Solid Waste and Emergency Response
Office of Superfund Remediation and Technology Innovation
February 2005
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Chevron Cincinnati Facility, Hooven, OH
4.0 PERFORMANCE OBJECTIVES [1]
The CMS proposed an overall site strategy using a tiered approach of identifying Corrective Action
Objectives in the form of short-term protectiveness goals, intermediate performance goals, and final
cleanup goals. EPA's final cleanup goals for the site are "to return 'usable' groundwaterto its maximum
beneficial use, wherever practicable, within a time frame that is reasonable given the particular
circumstances of the facility." Based on the conceptual design in the CMS, the specific goal for SEAR at
the site was to reduce LNAPL saturation to between 0.5% and 1%, at which level, studies suggest that
SEAR would no longer be capable of mobilizing the LNAPL. If reduced to this level, the LNAPL was
expected to remain immobile after completion of the SEAR application. Table 2 in Section 3.2 lists the
cleanup goal for each of the COPCs identified in Section 3.
U.S. Environmental Protection Agency 16 February 2005
Office of Solid Waste and Emergency Response
Office of Superfund Remediation and Technology Innovation
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Chevron Cincinnati Facility, Hooven, OH
5.0 TECHNOLOGY DESCRIPTION AND EVALUATION
SEAR is an innovative and aggressive technology that has the potential to remediate LNAPL and may
allow for site redevelopment more quickly than other technologies. The following describes the SEAR
remediation system, as well as the PITT and CPT/ROST™ pilot characterization studies and additional
bench-scale studies used as a basis for evaluating SEAR as a remedial option for treating LNAPL at the
Chevron Cincinnati Facility.
5.1 PILOT-SCALE SITE CHARACTERIZATION STUDIES [1,3,4,5,6,7,8]
PITT and CPT/ROST™ pilot tests were conducted as part of a site characterization and method selection
field study to provide data used in the conceptual design and evaluation of a SEAR remedial approach for
the site. This study also served to determine if a less costly and time consuming (compared to
conventional soil-core and LNAPL testing) characterization method, such as CPT/ROST™, could be used
to effectively investigate the nature and extent of LNAPL contamination throughout the site.
5.1.1 PITT Pilot Test
The in situ migration characteristics of LNAPL and heterogenous subsurface characteristics can cause the
pattern of LNAPL distribution to be complex. Using conventional methods (such as soil-core sampling)
that only examine a small fraction of the in situ volume can lead to significant inaccuracies in the estimates
of the LNAPL saturation and volume, and may not provide information about the LNAPL distribution
patterns. Application of PITTs can provide better information about the in situ LNAPL conditions at some
sites. Unlike discrete soil sampling, a PITT allows a spatially integrated examination of the in situ volume.
PITT is an intensive characterization approach that employs the injection of multiple tracer chemicals,
such as aliphatic alcohols, into the subsurface under controlled conditions in which the groundwaterflow
rate and direction are known. Typically, one of the tracers does not react or partition to the LNAPL, while
the others partition into the LNAPL at varying rates. During testing, the appearance of these tracers at
downgradient extraction wells at different rates is measured dynamically. Because each tracer has
specific partitioning characteristics with the aquifer material and LNAPL within the smear zone, these data
can be used to develop an accurate (estimated to be +/-25%) estimate of LNAPL saturation in the
subsurface. The data developed from a PITT can then be used to optimize the remedial design and
SEAR operations. Figure 4 is a schematic of a PITT.
U.S. Environmental Protection Agency 17 February 2005
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Chevron Cincinnati Facility, Hooven, OH
During the PITT conducted at the Chevron, Cincinnati site, controlled conditions were created through the
automation of injection and extraction wells along with the injection of fresh water into peripheral wells to
U.S. Environmental Protection Agency 18 February 2005
Office of Solid Waste and Emergency Response
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Chevron Cincinnati Facility, Hooven, OH
Figure 4. Schematic of a Partitioning Interwell Tracer Test
From
oniy
From water source CM
inj-i-jctate
35
To C-ooiro! T'-Piie-r and Holding Tank
? - {h-X't 19 cipni}
i (EK2 18
r-f- EX
-------
Chevron Cincinnati Facility, Hooven, OH
Source: Radian International and Duke Engineering Services, 1999
U.S. Environmental Protection Agency
Office of Solid Waste and Emergency Response
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Chevron Cincinnati Facility, Hooven, OH
create a constant hydraulic head. The partitioning characteristics within the smear zone were established
through rigorous bench testing. The tracers used for PITT testing at this site included various aliphatic
alcohols. PITT testing identified typical LNAPL saturation in the range of 1 to 5% within the smear zone.
Figure 1 in Section 2 of this case study shows an areal photograph of the PITT test area.
5.1.2 CPT/ROST™ Pilot Test
Petroleum-based fuels, such as gasoline, diesel, and kerosene, and other polyaromatic hydrocarbons,
such as coal tar and creosote, contain compounds that fluoresce when excited by ultraviolet light. A soil
sample contaminated with petroleum substances will exhibit fluorescence intensity that is proportional to
the contaminant concentration. The concentration of the hydrocarbon fraction in an unknown sample can
be determined by comparing its fluorescence intensity to that of calibration standards.
The ROST™ detects the presence and quantitates the amount of aromatic petroleum hydrocarbons by
the laser-induced fluorescence in the sample. It is a tunable dye laser-induced fluorescence system
designed as a field screening tool for detecting petroleum hydrocarbons in the subsurface. The ROST™
system uses a pulsed laser coupled with an optical detector to make fluorescence measurements via
optical fibers. The measurement is made through a sapphire window on a probe that is pushed into the
ground with a truck-mounted cone penetrometer (CPT). As the instrument is advanced through the soil,
hydrocarbons are detected in situ. The ROST™ technology is intended to determine both the quantity, by
measuring total fluorescence, and type, by measuring the intensities of several different wavelengths of
fluorescent light, of LNAPL. The direct measurements of fluorescence are typically calibrated against
known standards generated via bench scale testing of soil-core and site-specific LNAPL samples.
The pilot test of CPT/ROST™ at the Chevron Cincinnati Facility consisted of 15 pushes in locations where
PITT injection, extraction, and monitoring wells were being installed. The pushes were advanced to
depths ranging from 36 to 40 feet bgs (through the smear zone) during which geophysical measurements
(based on CPT tip resistance and sleeve friction) were made concurrently with fluorescence
measurements. Fluorescence measurements were converted to percent saturation measurements based
on calibration data from soil-core samples collected concurrently in some locations. Based on the data
from the pilot test, the vendor concluded that CPT/ROST™ was capable of semi-quantitatively delineating
the vertical extent of LNAPL within the smear zone. It was capable of determining minimum, maximum,
and average LNAPL saturation at a very fine frequency (less than 0.5 foot). However, the study
concluded that CPT/ROST™ can only provide accurate measurements of percent saturation if reference
samples are taken over a wide range of concentrations and if various soil types and LNAPL types are
used to calibrate the ROST™ for the specific site. The vendor noted that, in some cases, two or more
U.S. Environmental Protection Agency 21 February 2005
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Chevron Cincinnati Facility, Hooven, OH
adjacent ROST™ pushes may be required in locations where quantitative measurements of LNAPL
saturation are required.
Based on the results of the PITT and the CPT/ROST™ pilot tests, the vendor concluded that the extent of
site-wide LNAPL could be investigated at the site using CPT/ROST™ as the primary characterization tool,
supported by a program of soil-core testing and LNAPL sampling to calibrate the CPT/ROST™. In
addition, this testing also resulted in a better understanding of the conditions within the smear zone at the
PITT test site, such as the following:
The vertical boundaries of the smear zone appeared to be distinct (a sharp increase in LNAPL
saturation within 1 -2 feet)
Average LNAPL saturation within the saturated zone is about 3.5% with some strata containing an
average of as much as 6 - 8%
Based on ROST™ data (the PITT test used at this site was not capable of measuring LNAPL
saturation in the unsaturated zone), average LNAPL saturation within the unsaturated zone
appeared to be similar to that in the saturated zone (average of about 3.5%); however, higher
saturations (as high as 13%) were identified in certain strata, most significantly directly above the
water table
Aquifer materials were heterogeneous in both vertical and horizontal dimensions
LNAPL saturation within the smear zone was less than expected (1 - 5%)
5.2 ADDITIONAL BENCH-SCALE STUDIES
Additional bench-scale studies, including a LNAPL characterization bench study, a film drainage and
wettability characterization bench study, and a phase behavior testing of surfactants bench study, were
conducted to provide further information to evaluate the feasibility of using SEAR at the site.
5.2.1 LNAPL Characterization Bench Study
A characterization of LNAPL samples collected from the Chevron Cincinnati Facility was conducted to
provide data that could be used to develop the conceptual design for SEAR and the other remedial
alternatives for the site. Some of the results of these analyses were presented previously in this report, in
U.S. Environmental Protection Agency 22 February 2005
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Chevron Cincinnati Facility, Hooven, OH
Table 1. This information was used as a basis to select surfactants that would potentially be capable of
achieving ultra-low interfacial tensions and ultra-high contaminant solubilization of the LNAPL at the site.
5.2.2 Film Drainage and Wettability Characterization Bench Study
Centrifuge experiments were conducted to better quantify the effect of naturally occurring film drainage
and to determine the wettability of the aquifer material in the presence of the LNAPL at the site. The
results of this testing concluded that when the groundwater level at the site is low, the LNAPL present in
the smear zone above the water table likely will drain to the water table to form a free-phase LNAPL layer,
which is consistent with the "pancake" model of LNAPL distribution. As noted in Section 3.2, new
research into the behavior of LNAPL indicates that it may follow an different model that is based on the
capillary forces that soil exerts on water and LNAPL in addition to density differences.
Wettability testing was used to provide data about how LNAPL reacts with and flows within the aquifer
material at the site. The results of this testing suggest that LNAPL could be located in inaccessible pores
in types of soil with narrow pore spaces within the aquifer, potentially constraining the effectiveness of
conventional pump and treat as well as SVE. This fact suggested that the use of anionic surfactants,
which can be used to change the aquifer wetting characteristics, could be used to increase contaminant
recovery efficiencies at the site.
5.2.3 Phase Behavior Testing of Surfactants Bench Study
Phase behavior experiments were conducted to design and select a surfactant formulation with the most
desirable behavior (most rapid mixture equilibrium; low viscosity of the surfactant and contaminant-rich
microemulsion; and the absence of liquid crystals, gels, and emulsions) in the presence of the site LNAPL.
Table 5 lists the commercial and chemical names of the surfactants that were tested in these experiments
along with their manufacturer and type.
These seven different surfactants were used to prepare 25 different surfactant formulations, which were
tested on the site LNAPL by mixing each formulation with site LNAPL and groundwater, agitating for set
periods of time, and measuring the characteristics of the resulting mixture. In addition, secondary butanol
(2-butanol) was incorporated as a cosolvent into some of the surfactant configurations. Calcium chloride,
an electrolyte, was also incorporated into some of the surfactant configurations to control contaminant
solubilization and interfacial tension reduction. Each configuration was tested with pure-phase site
LNAPL. The following two surfactant formulations were identified as having the most desirable
characteristics (all percentages shown are percent weight):
U.S. Environmental Protection Agency 23 February 2005
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Chevron Cincinnati Facility, Hooven, OH
Mixture of 4% Alfoterra 123-4-PO sulfate, 8% 2-butanol, and 0.5% Emcol-CC-9, and calcium
chloride
Mixture of 4% Alfoterra 123-4-PO sulfate, 8% 2-butanol, and calcium chloride
Table 4. Surfactants Tested in Phase Behavior Experiments
Commercial Name
Alfoterra 123-4-PO sulfate
Alfoterra 123-8-PO sulfate
Alfoterra 145-4-PO sulfate
Emcol CC-9
Emcol CC-42
EthoquadO/12
LB-65 (Non-ionic)
Chemical Name or Description
beta-Branched, alcohol polypropoxy
sulfate
beta -Branched, alcohol polypropoxy
sulfate
beta -Branched, alcohol polypropoxy
sulfate
Polypropoxy tertiary amine (MW600)
Polypropoxy tertiary amine (MW2500)
Bis-(2hydroxyethyl)oleyl amine (MW
403)
Butanol polypropoxylate
(MW 340)
Manufacturer
Condea Vista
Condea Vista
Condea Vista
Witco
Witco
Akzo Nobel
Union Carbide
Type
Anionic
Anionic
Anionic
Cationic
Cationic
Cationic
Non-ionic
Source: Radian International and Duke Engineering & Services, 2000
Both of these formulations had equilibrium times on the order of 10 to 60 minutes, high contaminant
solubilization, and low microemulsion viscosity. These surfactant configurations were recommended for
soil column experiments to validate their performance under site subsurface conditions. Information about
whether soil column experiments were conducted was not provided.
24
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February 2005
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Chevron Cincinnati Facility, Hooven, OH
5.3 DESCRIPTION OF SEAR TECHNOLOGY [1,3,4]
Surfactants are surface active agents that have two different chemically active parts, a hydrophilic head
and a hydrophobic tail. Thus, they exhibit solubility in both water and oil. It is this unique property that
allows these agents to greatly increase the solubility of nonaqueous-phase liquids (NAPLs) in water for
NAPL removal by enhanced solubilization, and also to greatly reduce the interfacial tension between the
NAPL and water phases for NAPL removal by enhanced mobilization. SEAR involves the injection of a
surfactant solution consisting of surfactant, electrolyte, cosolvent (i.e., alcohol), and water. Surfactant
flooding is followed by water flooding to remove injected chemicals and solubilized or mobilized
contaminants remaining in the aquifer. The extracted fluids are treated aboveground to separate the
NAPL-phase and dissolved-phase contaminants for disposal. The surfactants can be recovered for
reinjection if desired. A conceptual illustration of the SEAR process is shown in Figure 5.
U.S. Environmental Protection Agency 25 February 2005
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Chevron Cincinnati Facility, Hooven, OH
Figure 5. Conceptual Model of Surfactant Enhanced Aquifer Remediation
Suraclant
lection
reatnenl of
Soiubhzed NAPL
Extract on c? NAPL
a":d Surfactant
U.S. Environmental Protection Agency
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February 2005
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Chevron Cincinnati Facility, Hooven, OH
Source: Naval Facilities Engineering Service Center, 2001.
U.S. Environmental Protection Agency 27 February 2005
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Chevron Cincinnati Facility, Hooven, OH
Based on the results of the studies described in Sections 5.1 and 5.2, other characterization work
conducted at the site, and the assumption that 8 million gallons of LNAPL remained at the site, a
conceptual design for a SEAR system was developed. The conceptual design assumed that surfactant
injection would take place only when the site water table was low and much of the LNAPL trapped in the
smear zone had drained and collected on top of the water table. It assumed that such an approach would
minimize the total volume of the treatment area, thereby reducing the volume of surfactant required.
Since surfactant was estimated to be the largest cost element in SEAR, this approach was expected to
minimize the overall remediation costs. However, this assumption is based on the "pancake" model of
LNAPL distribution, which recent research has shown may not accurately describe its behavior. The
characterization and design activities described in this report were conducted before the current model
was widely accepted, and were based, in part, on the "pancake" model. The effects of applying the
current model to the test results and design assumptions described here have not been assessed. The
LNAPL models are described in more detail in Section 3.2.
The SEAR conceptual design was geared toward maximizing LNAPL recovery and reducing residual
LNAPL saturation to between 0.5 and 1%. The design involved conducting SEAR in 500-foot-long, 100-
foot-wide panels; each panel having between 30 and 50 central injection wells (spaced 10 to 15 feet on
center) and a similar number of extraction wells. One of the two surfactant formulations identified during
Phase Behavior Testing would be injected to mobilize the LNAPL.
The injection/extraction system was designed as a dual-line system, in which a row of central injection
points for surfactant is placed between two rows of extraction points situated parallel to the injection
points, 50 feet away on either side. The design used peripheral wells to inject clean water to provide
hydraulic control by raising the hydraulic head outside of the treatment area, inducing groundwaterflow
inward toward the extraction wells. The design also considered (but did not incorporate) that injected
polymers, foams, or water injected below the surfactant flood could be used to minimize the volume of
surfactant wasted due to downward channeling beneath the smear zone.
The groundwater extracted from the SEAR operations would contain surfactant, mobilized LNAPL, and
dissolved contaminants. The options considered for managing the groundwater extracted during SEAR
implementation included treatment and discharge to surface water, and treatment and reuse as injection
water in the SEAR application. Treating the extracted fluid containing LNAPL, surfactant, and
contaminated groundwater generated during SEAR to a point where it could be discharged to the river
was deemed to be uneconomical (estimated to require reducing contaminant concentrations by three to
six orders of magnitude). The system was assumed to be required to meet the same discharge
U.S. Environmental Protection Agency 28 February 2005
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requirements as the existing site P&T system. Therefore, the conceptual design assumed that extracted
groundwater would be treated to remove more than 95% of hydrocarbons and then reinjected. Detailed
design of a treatment train for the extracted groundwater was not conducted, but the CMS indicated that
such a treatment train could include phase separation followed by macroporous polymer extraction
(MPPE). Additional information supporting these assumptions, specific cost estimates, and design details
were not available in the references used for this report.
As a remedial alternative in the groundwater CMS, SEAR was incorporated with ongoing groundwater
containment through pump and treat for hydraulic control, institutional controls, and SVE. This alternative
represented the most aggressive approach evaluated for the site in the CMS. Hydraulic containment and
institutional controls (which were not specifically described in the CMS) would be used to continue to
minimize off-site migration of contaminants and to minimize impact on future site tenants. SEAR and SVE
would be used in conjunction during periods when the groundwater table was seasonally low. SEAR
would be used to flush most of the LNAPL from the saturated zone and remove the free-phase LNAPL,
while SVE would be used to remediate the residual soil contamination in the vadose zone. SEAR would
be implemented in panels; each treated for a few weeks, after which time the operation would move to the
next downgradient panel. This process would extend over several low groundwater seasons, progressing
downgradient until the entire site was treated. SVE would be installed and operated immediately after
SEAR was completed in a particular panel until it became ineffective (estimated in the CMS to be
approximately eight years).
5.4 CMS EVALUATION OF SEAR TECHNOLOGY [1,5,6]
The following discussion summarizes the evaluation of the SEAR technology discussed in the CMS. The
time to reach final cleanup goals and present value costs included in the CMS are estimates. The
groundwater CMS evaluated the remedial alternative incorporating SEAR based on the following criteria:
Time to Reach Final Cleanup Goals - The remediation approach incorporating SEAR was the most
aggressive source removal approach evaluated and the only one that was expected to remove residual
LNAPL saturation in the smear zone. The conceptual design included a combination SEAR/SVE system
that would be expected to reduce residual LNAPL contamination by 99% or better, after which hydraulic
control and monitored natural attenuation would be used to reduce groundwater contaminants to below
final cleanup goals (MCLs). The CMS estimated that this system would take eight years to implement
across the entire site. Using this assumption, dissolution modeling conducted as part of the CMS
suggested that it would take an additional 93 years for benzene (which is the groundwater contaminant
currently present at the highest multiple of its cleanup goal) in groundwater to dissipate (solely through
U.S. Environmental Protection Agency 29 February 2005
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dissolution) to concentrations less than cleanup goals. The CMS includes an estimate of 458 years to
achieve cleanup goals using only hydraulic control. This value of 458 years does not include natural
losses in the vapor phase, which were later found to be significant.
Present Value Cost - The CMS contains an estimate of the total present value cost (incorporating an
assumed 1.94 percent effective annual discount rate) to reach cleanup goals at the site using a remedial
approach incorporating SEAR compared to the total costs for other alternatives. The total present value
cost estimate for using the SEAR/SVE remedial approach in the CMS to reach groundwater cleanup goals
for the site is $150 million, compared to a total present value costs of $51 million to reach groundwater
cleanup goals using no source treatment with only ongoing hydraulic control and MNA. The total cost for
the SVE/SEAR approach includes the capital and O&M costs associated with the SVE/SEAR system, as
well as the on-going containment portion of the alternative. The capital cost of the SVE/SEAR system,
estimated at $90 million, was not discounted and assumed to be incurred in the first year of remedy
implementation. The present worth of O&M for this system is $16 million over 8 years; however, this O&M
value only includes the SVE system. The O&M of the SEAR portion was assumed to be incurred in the
first year of its implementation to simplify the calculation of this cost, and was included in the capital cost
for this alternative. For the containment portion of the alternative, free product recovery was estimated to
continue for 16 years with approximately 30,000 gallons being removed each year. The cost for free-
product disposal is currently $0.67/gallon. It was also assumed that the fluidized bed reactors would need
to be replaced every 25 years at an estimated cost of $2.3 million with the first replacement taking place in
10 years. This cost estimate is for a full-scale SEAR system. Actual cost data for the SEAR testing
conducted at this site are not available. Table 5 summarizes these costs. Additional details on the costs
for SEAR application were not provided in the references used for this report.
Table 5
Present Worth of All Costs for Two Remedial Approaches at the Chevron, Cincinnati Facility
Remedial Approach
Hydraulic Containment and MNA
SVE, SEAR, Hydraulic
Containment, and MNA
Present Worth ($ Millions)
Initial Source Removal
Capital
0
90
Operation and
Maintenance
0
16
Ongoing
Site
Operations
49
42
Additional
Fixed
Costs1
1
1
Total
50
150
Additional fixed costs are described in the GWCMS, Appendix B.
30
U.S. Environmental Protection Agency
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Chevron Cincinnati Facility, Hooven, OH
Source: GWCMS, 2001
Cost Sensitivity to Effects of Biodegradation Rate And Groundwater Velocity - Effects of
biodegradation of groundwater contaminants was not factored into the CMS analysis. The CMS
concluded that, although biodegradation may occur at the site, it would have little impact on the present
worth costs because biodegradation generally only affects duration far in the future when the changes in
discounted value are minimal. It further stated that biodegradation in areas with LNAPLs was expected to
be minimal, because of a lack of electron acceptors necessary for bioremediation. Additional details on
this assumption were not provided in the references used for this report.
The CMS based its analysis on the effects of groundwater velocity on an assumed groundwater flow
velocity of 4 feet per day, but acknowledged that the groundwater velocity in some areas of the site may
be slower. The value of 4 feet per day reflects nearby groundwater pumping. However, the CMS
concluded that, although a slower groundwater velocity than what was assumed in the dissolution model
(4 feet/day) would increase the time needed to reach cleanup goals via dissolution, adding additional costs
so far out in the future would have minimal effects on the present worth cost.
Compatibility with Site Redevelopment - Currently, there are plans to redevelop the site for mixed
commercial, industrial, and recreational uses. The plans assume that groundwater hydraulic control will
be ongoing during and after site redevelopment (that is, groundwater will not be required to meet final
cleanup goals prior to beginning site redevelopment). The CMS concluded that if the SEAR/SVE
approach were implemented, site redevelopment could not occur until the remedy was completed. The
eight-year schedule for SEAR/SVE was based on the time needed to complete infrastructure upgrades,
application of SEAR/SVE, and site plans for redevelopment. The estimated time to implement SEAR
alone at the site was 5 years.
U.S. Environmental Protection Agency 31 February 2005
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Chevron Cincinnati Facility, Hooven, OH
6.0 OBSERVATIONS AND LESSONS LEARNED
General
The CMS did not recommend SEAR for remediation of the Chevron Cincinnati Facility because this
remedy could not be completed in a reasonable time frame (the remedial approach including SEAR would
require 100 years), it was more expensive than an alternative remedy ($150 million present worth for a
remedial approach including SEAR vs. $50 million for hydraulic containment and MNA), and the SEAR
technology had not been demonstrated on the scale needed at this site. Based on the above evaluations,
the CMS recommended that remediation of groundwater at the site be conducted through ongoing
hydraulic containment using pump and treat, rather than implementing source removal, such as the
SEAR/SVE alternative.
The data presented for cost and time for treatment are from the CMS. Different assumptions or
methodologies may have resulted in different conclusions. Although the CMS did not recommend SEAR
at the Chevron Cincinnati Facility, the evaluation of SEAR at this site resulted in a number of observations
and lessons learned about this technology that may be helpful when SEAR is evaluated at other sites. For
example:
PITT and CPT/ROST™ [31
PITT testing was conducted to provide a basis for comparing the performance of CPT/ROST™ in
accurately measuring the vertical and horizontal extent of LNAPL saturation at the site. PITT
proved capable of estimating the percent LNAPL saturation within the saturated portion of the
smear zone. Although PITT is capable of characterizing the unsaturated zone using gas tracers,
this type of characterization was not used.
Data from the CPT/ROST™ pilot test suggested that this technology, as it was applied during the
testing, was only capable of semi-quantitatively delineating the vertical extent of LNAPL within the
smear zone. In order to achieve more accurate measures of LNAPL saturation using this
technology, a more comprehensive calibration approach or duplicate samples would be needed.
SEAR [1,4,5,6]
The conceptual model for the LNAPL source removal using SEAR assumed an LNAPL volume of
8 million gallons and an average benzene mole fraction of 0.4%. The estimate of the LNAPL
U.S. Environmental Protection Agency 32 February 2005
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Chevron Cincinnati Facility, Hooven, OH
volume was based on an area of 200 acres, a smear zone thickness of 10 feet, an average
LNAPL saturation of 4%, and a soil porosity of 0.3. The estimate of 8 million gallons of LNAPL
was based on the "pancake" model of LNAPL behavior in the subsurface. Subsequent estimates
based on a different model indicated that the volume of LNAPL was significantly less. As of June,
2004, the estimate for residual LNAPL at the site was 3.5 million gallons.
Bench-scale studies concluded that SEAR potentially could be used to reduce LNAPL saturation
at the site to less than 1% residual saturation through mobilization and solubilization of LNAPL
using a surfactant formulation.
Bench-scale studies that evaluated surfactant formulations and their interactions with LNAPL from
the site identified a surfactant formulation, containing proprietary anionic and cationic surfactants,
a cosolvent (2-butanone), and an electrolyte (calcium chloride), that was optimized for SEAR
treatment at this site. However, the bench-scale study concluded that soil column testing would
be necessary to determine whether the surfactant formulation would behave adequately during in
situ SEAR.
The conceptual model for LNAPL source removal using SEAR assumed that SEAR would be
conducted during periods when groundwater at the site was relatively low, minimizing the volume
of subsurface groundwater that would need to be treated. Since the surfactant cost was expected
to be the largest cost component of SEAR, such an approach was expected to minimize cost.
However, SVE would need to be used in conjunction with SEAR because SEAR would not treat
the contaminated vadose zone during low groundwater periods.
The conceptual model for LNAPL source removal using SEAR was based on the assumption that
the resulting extracted LNAPL/groundwater emulsion could be treated using aboveground
technologies to adequately recover surfactant and to reduce contaminant levels to the extent that
the treated water could be reinjected. The CMS noted that the feasibility of this assumption
needed to be proven.
The CMS noted that the implementation of SEAR in the piecemeal manner (working its way
downgradient) described in the conceptual design could delay redevelopment of the site because
of the dense network of wells required. SEAR would have to be completed in any given area
before site redevelopment could begin. In the case of this site, the most downgradient
contaminated area, which would have to be treated last under the conceptual design in the CMS,
would benefit from the earliest development.
U.S. Environmental Protection Agency 33 February 2005
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Chevron Cincinnati Facility, Hooven, OH
Site contacts stated that, when SEAR is used to remove LNAPL from large sites, such as
refineries and tank farms, it is generally applied only to the "hot zone". Planned applications at
other sites are designed to use SEAR to remove LNAPL "hot zones" and create an "attenuation
zone" where benzene concentrations will be reduced.
U.S. Environmental Protection Agency 34 February 2005
Office of Solid Waste and Emergency Response
Office of Superfund Remediation and Technology Innovation
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Chevron Cincinnati Facility, Hooven, OH
7.0 SITE CONTACTS
Site Contact:
Mark Lyverse
ChevronTexaco
Senior Hydrogeologist
Ground Water Technology Team
100 Chevron Way
Richmond, CA 94802-0627
(510)242-1080
mlYv@chevrontexaco.com
Technology System Vendor Contact:
Duke Engineering & Services
9111 Research Boulevard
Austin, TX 78758
EPA Regulatory Contact:
Christopher Black
U.S. EPA Region 5
Corrective Action Section, DE-9J
77 West Jackson Boulevard
Chicago, IL 60604-3590
(312)886-1415
black.christopher@epa.Qov
State Regulatory Contact:
Timothy Staiger
Ohio Environmental Protection Agency
Office of Solid Waste and Hazardous Waste Management
Southwest District Office 401 East Fifth Street
Dayton, OH 45402
(937) 285-6089
U.S. Environmental Protection Agency 35 February 2005
Office of Solid Waste and Emergency Response
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8.0 REFERENCES
1. Radian International LLC. 2001. Chevron Cincinnati Facility Groundwater Corrective Measures
Study (GWCMS), Draft Rev. 0. October 26.
2. U.S. Environmental Protection Agency. 2003. Statement of Basis for Sludges and Contaminated
Soils for Chevron/Texaco Cincinnati Facility, Hooven, Ohio (EPA I.D. No. OHD 004 254 132).
June.
3. Radian International LLC and Duke Engineering & Services Inc. 1999. Chevron Cincinnati
Facility Site Characterization Method Selections, Volume I A: Report, Final. February.
4. Radian International LLC and Duke Engineering & Services Inc. 2000. Final Report, LNAPL
Characterization and Surfactant Selection for the Chevron Cincinnati Facility SEAR Development
and Feasibility Study. June.
5. Communication from Richard Jackson, Intera, Inc. to Ellen Rubin, U.S. EPA. April 10, 2004.
6. Communication from Mark Lyverse, Chevron Texaco, to Ellen Rubin, U.S. EPA. May 17, 2004.
7. Naval Facilities Engineering Service Center. 2001. Cosf and Performance Report for
Surfactant-Enhanced DNAPL Removal at Site 88, Marine Corps Base Camp Lejeune, North
Carolina. October.
8. U.S. Environmental Protection Agency. Undated. The Rapid Optical Screening Tool (ROST™ )
Laser-Induced Fluorescence (LIF) System for Screening of Petroleum Hydrocarbons in
Subsurface Soils.
9.0 ACKNOWLEDGMENTS
This report was prepared for the U.S. Environmental Protection Agency's Office of Solid Waste and
Emergency Response, Office of Superfund Remediation and Technology Innovation. Assistance was
provided by Tetra Tech EM Inc. under Contract No. 68-W-02-034.
U.S. Environmental Protection Agency 36 February 2005
Office of Solid Waste and Emergency Response
Office of Superfund Remediation and Technology Innovation
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