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only low levels of three PNAs and two metals; 3) results of surface
soil samples showed only low levels of contaminants in only a few
isolated areas, except for one sampling location which was located
in the southwest corner of the Main Waste Area where elevated
levels of lead (greater than 500 ppm) were detected; 4) no organic
compounds were detected in Turtle Bayou, to which intermittent
streams and ditches convey surface runoff from the site; 5) the
RCRA Vault which contains high chemical concentrations and is
located in the Main Waste Area, is currently fenced and capped to
prevent exposure to trespassers and/or wildlife.
A wetlands determination was made at the site and indicated that
the site does not contain any wetlands. Although a variety of
terrestrial and aquatic biota frequent the area, these receptors
are not expected to be adversely impacted by the chemicals at the
site since: 1) surface water samples collected at the site did not
reveal chemical concentrations above background levels and, 2) the
results of sediment and surface soil sampling (as stated
previously) . Since the chemicals at the site .are expected to have
minimal migration in the media of potential concern to non-human
receptors, potential ecological risk evaluations (e.g., biota
sampling) were not conducted.
During the remedial investigation no endangered species were
identiried at the site.
Sources of Uncertainty
Uncertainty is inherent in the risk assessment process. In
addition to the use of many conservative assumptions and
approximations, the identification and analysis of environmental
conditions is difficult and inexact. There are four broad areas
where uncertainties may be found in the risk assessment process:
1) Collection of site-specific data
2) Receptor populations
3) Chemical toxicity
4) Risk characterization
When the risk assessment was produced, it was assumed that the
sampling activities fully characterized the chemicals at the site,
and that the concentrations used in this assessment were
representative of the site. This assumption was incorrect as
demonstrated by the Supplemental RI conducted by WESTON under
contract to ARCO Chemical, during which additional waste areas and
high concentrations of contaminants were discovered. As the Petro-
chemical Systems, Inc. site covers approximately 500 acres and no
official records exist as to where the dumping occurred on the
site, whether or not all the waste areas for the entire site have
71
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been fully identified remains uncertain.
When evaluating the potential effects on future populations, it was
assumed that the contaminants do not degrade, but rather remain at
specific concentrations for many years. This assumption may
introduce significant uncertainty in the risk assessment process.
However, this assumption is a conservative assumption and thus
would more likely overestimate any future risks.
Most of the toxicity information used in risk assessment
calculations is obtained from animal studies, although
epidemiological studies conducted on specific human populations may
sometimes be available as a source of toxicity information. For
the chemicals evaluated in this risk assessment, animal data served
as the principal basis for the assessment of risks. Extrapolation
from animals at high doses to humans potentially exposed to lower
doses may be a major source of uncertainty.
Assumptions used in the risk characterization calculations of
chemical intakes can provide considerable uncertainty in a risk
assessment. Intake assumptions include soil ingestion rates,
inhalation rates, dermal contact rates, mobility factors, and
adsorption factors. The intake assumptions used in this risk
assessment are obtained both from peer-reviewed scientific
literature and from U.S. EPA references. Uncertainties in this
assessment may exist from use of these assumptions.
To reduce uncertainties, directly measured soil and ground water
concentrations were used to evaluate risk. In summary, although
several assumptions are made in conducting this risk assessment,
these assumptions are conservative assumptions and would therefore
tend to err on the conservative side.
Remediation Goals
The contaminated soil was determined to be a principal threat at
the site because of the soil's impact on ground water. The
remedial objectives set for the contaminants in the soil will
ensure that the potential for them to act as a continuing source
of ground water contamination is eliminated, thus allowing the
ground water to be used as a future source of drinking water.
The contaminated ground water was also determined to be a principal
problem at the site because of the potential exposure of the public
to the site contaminants and because of the threat of migration of
contaminants to deeper ground water zones. The remedial objective
for the contaminated ground water is to reduce the amount of
contamination to the Maximum Contaminant Limits (MCLs) or to human
health-based standards. When MCLs were not available (e.g.,
naphthalene), health based standards were used. Achieving these
objectives will help to minimize the risks associated with the
72
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contaminated ground water.
The remedial objectives are to reduce contaminant concentrations
in the ground water to the drinking water Maximum Concentration
Limits (MCLs) set for benzene, ethylbenzene, and xylene. MCLs are
the maximum concentrations allowed for public water supplies by
federal law. The remedial objective for lead is based on an EPA
policy setting a goal for lead concentrations in ground water at
Superfund sites. The objective for naphthalene was to reduce the
amount that could be ingested to a concentration that would not
have adverse effects on human health.
The remedial levels the EPA has determined will provide protection
of human health and the environment for the Petro-Chemical Systems,
Inc. site, based on a residential scenario, are the following:
SOIL CRITERIA
Benzene 10 parts per million (ppm) See * below
at depths less than 10 feet See * below
0.35 ppm at depths greater
than 10 feet *
Lead 500 ppm See ** below
Naphthalene 70 ppm Health Based
Value
GROUND WATER
Benzene 5.0 parts per billion (ppb) MCL
Ethylbenzene 700 ppb MCL
Xylene 10,000 ppb MCL
Naphthalene 327 ppb Health Based
Value
Lead 15 ppb Action Level
* The remedial goal for benzene in the soil was determined based
on the potential of the benzene contamination in the soil to
leach into the underlying ground water aquifer resulting in
benzene contamination of the ground water exceeding the
benzene MCL for drinking water. The SESOIL model was used to
do this determination. It should also be noted that if
detectable concentrations of benzene are found at depths
greater than 10 feet, the entire soil column (from the ground
surface to the maximum depth of contamination) would be
remediated to a contaminant level of 0.35 ppm.
** Lead concentration was based on the Interim Guidance on
establishing Soil Lead Cleanup Levels at Superfund Sites,
September 7, 1989.
Table 6-15 shows the estimated cancer risk and chronic hazard
indexes that will be attained by achieving these remedial levels.
73
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QUALITY,
ORIGINAL
-------
As stated previously, because the contaminants of concern were
detected in isolated areas of the site and were not detected in the
sediments or surface water in the bayou, ecological impacts from
contamination at Petro-Chemical Systems, Inc. are not expected.
Remedial action goals were set for the protection of human health
from future ingestion of the shallow ground water at the site.
VII. DESCRIPTION OF ALTERNATIVES
A FS and subsequent FFS were conducted to develop and evaluate
remedial alternatives for Operable Unit 2 at the Petro-Chemical
Systems site. Remedial alternatives were assembled from applicable
remedial technology process options and were initially evaluated
for effectiveness, implementability, and cost. The alternatives
meeting these criteria were then evaluated and compared to nine
criteria required by the NCP. In addition to the remedial
alternatives, the NCP requires that a no-action alternative be
considered at every site. The no-action alternative serves
primarily as a point of comparison for the other alternatives.
Each remedial alternative acknowledges the activities conducted
under Operable Unit 1 (Frontier Park Road) as a starting point for
the activities to be conducted under this ROD. The alternatives
described in this ROD address the remaining identified source areas
and ground water contamination at the site.
The remedial levels set for the Petro-Chemical Systems, Inc, site
(discussed in the Summary of Risk section) are the treatment levels
which the selected remedy will need to attain. Attainment of these
levels will be protective of human health and the environment.
The descriptions of remedial alternatives are separated into those
addressing soil contamination and those addressing ground water
contamination.
Soil Contamination Remedial Alternatives
The alternatives for the soil remediation are the following:
Alternative 1:
Alternative 2:
Alternative 3:
Alternative 4:
Alternative 5:
Alternative 6:
Alternative 7:
Alternative 8:
Alternative 9:
NO ACTION
SLURRY WALL AND CAP
BIOLOGICAL TREATMENT
SOLVENT EXTRACTION
INCINERATION
THERMAL STRIPPING
ON-SITE LANDFILL DISPOSAL
OFF-SITE LANDFILL DISPOSAL
VAPOR EXTRACTION with CATALYTIC OXIDATION
75
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Common Elements
Except for the "No Action" alternative, all of the alternatives
would include a number of common elements. All the alternatives
involve addressing approximately 297,800 cubic yards of
contaminated soil (as defined in Table 5-11) plus an additional
5,000 cubic yards from the Bayou Disposal Area. Elements common
to Alternatives 2 through 9 include: site preparation and the
installation of office, storage, and security facilities; the
installation of structures to control and treat surface-water run-
on and runoff; and restoration of the site surface to its original
condition with a vegetative cover upon completion of the remedial
action. Alternatives 3 through 8 would also involve excavation of
the contaminated soil prior to treatment and/or disposal. Air
monitoring and dust control will be implemented to minimize any
potential short-term adverse health effects during the remedial
construction alternatives for all of the alternatives. The
temporary RCRA vault will be dismantled and soil samples will be
taken beneath the lower liner of the vault to determine if
contamination is present and if remedial action is necessary to
address this soil.
s
Common ARARs
Chemical specific ARARs that will be met at the site include
the following:
The wastes identified on site were examined to determine whether
it qualified as RCRA hazardous wastes. The wastes were identified
as being RCRA characteristic hazardous wastes. Because the wastes
are RCRA waste, RCRA Land Disposal Restrictions are applicable for
the alternatives that involve removal and placement of contaminated
soils (alternatives 3-8). For alternatives not involving removal
and placement, LDRs are not applicable (Alternative 2); however,
RCRA regulations relating to closure may be relevant and appro-
priate for alternatives leaving the waste in place. LDRs are not
applicable for alternatives that use in-situ treatment (Alternative
9).
National Ambient Air Quality Standards (NAAQS), 40 CFR Part 50
establish regulations for specific air pollutants such as benzene,
which was determined to be one of the primary contaminants at the
site. Remedial alternatives 3-9 have the potential to generate
air emissions during implementation.
The Texas Air Control Board (TACB) General Rules require compliance
with EPA Federal Clean Air Act and NPAAQ Standards.
Common Location specific ARARs that will be met at the site
include the following:
The Executive Order on Floodplain Management requires Federal
agencies to evaluate the potential effects of actions they may take
76
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in a floodplain to avoid, to the extent possible, the adverse
impacts associated with direct and indirect development of a
floodplain. This ARAR is applicable since portions of the site are
within the 100-year floodplain of the Turtle Bayou tributary.
The Archeological and Historic Preservation Act, 16 USC 469, 40 CFR
6301(c) establishes procedures to provide for preservation of
historical and archeological data which might be destroyed through
alteration of terrain as a result of Federal construction projects
or Federally licensed activities or programs. No historical or
archeological data is known to exist at the site, but could be
encountered during remediation.
The Clean Water Act, Dredge or Fill Requirements (Section 404)
requires Federal agencies to address the impact of discharge of
dredge or fill material on aquatic systems. This may be an ARAR
if the remedial alternative selected involves discharge into Turtle
Bayou or other surface water.
Common Action specific ARARs that will be met at the site
include the following:
The Occupational Safety and Health Act regulates worker health and
safety. Under 40 CFR 300.38, requirements of the Act apply to all
response activities under the NCP.
The TACB General Rules (31 TAG Section 101) require compliance with
EPA Clean Air Act and NPAAQ Standards. The substantive
requirements for a permit may be required for operations at the
site. 31 TAC 101.4 is applicable since it prohibits the discharge
of air contaminants which may tend to be injurious to or adversely
affect human health or welfare, animal life, vegetation or
property, or to interfere with the normal use and enjoyment of
animal life, vegetation, or property.
Fugitive emissions monitoring as specified in TACB Regulation V or
EPA's New Source Performance Standards (40 CFR 60) or EPA's
National Emission Standards for Hazardous Air Pollutants (40 CFR
61) will apply.
The specific ARARs that will be met for each alternative will be
included in the description of each alternative.
Costs
All costs and times required to implement the alternatives are
estimates. These costs and time estimates are presented in Table
7-1. The cost have a degree of accuracy of +50% to -30%.
Alternative 1:
NO ACTION
The Superfund procedural regulations require that a no action
77
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alterative be considered at every site as a basis of comparison
when evaluating other alternatives. The no-action alternative
consists of taking no remedial action for the Petro-Chemical
Systems Site. However, the monitoring which is currently in effect
as a result of the Frontier Park Road Remediation should remain in
effect as contracted. The contract calls for monitoring of the
leachate collection system for the temporary landfill on-site and
maintaining the integrity of the road and road side drainage
ditches. The present worth cost of these activities is estimated
to be $1,440,000. "No Action" would not be protective of human
health. The potential future risks to human health from
contaminated ground water would still be present. Some naturally
occurring biodegradation might be expected, but this could be
offset by continued leaching of contaminated soil through surface
water infiltration. Therefore, "No Action" is not a favored
alternative by the EPA for the site. This alternative would not
decrease the toxicity, mobility, or volume of contaminants or
reduce the public health or environmental risks.
Alternative 2:
SLURRY WALL AMD CAP
This alternative involves isolating the contaminated soil in the
Main Disposal Area, the Temporary Office Area, the East Disposal
Area, the Frontier Park Road Area, the Power Easement Area, and the
Bayou Disposal Area to prevent direct contact and minimizing the
potential for contaminants to migrate to the ground water.
Following the site preparation activities, this alternative
involves construction of a slurry wall around the contaminated
soils and ground water with contaminant concentrations above the
remedial action goals as listed on page 73. The slurry walls would
be constructed of a soil-bentonite mixture and would tie into the
clay below the shallow water-bearing zone (approximately 30 ft)
below the ground surface in the Main Waste Area, the Frontier Park
Road Area, and the Temporary Office Area. The depth of the slurry
wall in the Power Easement Area would need to extend to about 55
feet below ground surface. In the Bayou Disposal Area, the depth
of the slurry wall would need to extend to about 40 feet below
ground surface to tie into the underlying clay. By tieing the
slurry walls into the clay layer, the migration of contaminants in
the soils and ground water would be minimized.
The areas would be graded and then covered with a multi-layered cap
meeting all federal requirements, consisting of clay, a plastic
membrane, topsoil, and vegetation. In the Main Waste Area,
contouring would be used to tie the cap of the existing disposal
area to the new cap to prevent ponding. The areas would be fenced
and posted to discourage trespassers. As portions of this site
are in the 100-year floodplain of Turtle Bayou, an important design
consideration would be to maintain the flood storage of the
tributary's watershed. A treatability test was not performed in
the feasibility study on this alternative.
79
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No treatment of the soil would be done before the caps were built.
Although the mobility of the contaminants in the soil and ground
water would be reduced, the volume of contaminants and the toxicity
would not be reduced.
EPA is directed by Section 121 of CERCLA, 42 U.S.C. § 9621, to
"utilize permanent solutions and alternative treatment technologies
or resource recovery technologies to the maximum extent
practicable" and to prefer remedial actions in which treatment
"permanently and significantly reduces the volume, toxicity, or
mobility of hazardous substances, pollutants, and contaminants as
a principle elem-nt."
Since hazardous waste will be left on the site, "landfill" closure
will be relevant. RCRA regulations affecting landfill closure
require the site to be capped, with a final cover designed and
constructed to provide long-term protection of human health and the
environment through minimization of the infiltration of liquids
through the capped area and proper maintenance of the integrity of
the cap over time with maintenance. This type of closure
anticipates that post closure care and maintenance will be carried
out at the site for at least 30 years. Since the waste would not
be consolidated, the landfill closure regulations are relevant and
appropriate. Long-term monitoring and maintenance of the site,
including ground water monitoring and repairs of the containment
areas, and a five year review would be required to guarantee the
effectiveness of this remedy.
If possible, deed recordation would be used to provide notice of
the waste on the properties. However, the State of Texas does not
have a mechanism to force a landowner to record anything on a deed,
and as the water rights are also the landowner's property,
institutional controls are difficult to enforce. Deed recordation
can only be requested.
The alternative would take approximately 1 year to implement, and
the present worth cost of these activities is estimated to be
$8,500,000. EPA does not favor this alternative since it does not
utilize treatment to reduce the mobility, toxicity, or volume of
the contaminants.
Alternative 3:
BIOLOGICAL TREATMENT
Biological treatment is an innovative technology that uses bacteria
to degrade organic contaminants in the soil. These bacteria are
capable of degrading organic compounds into water and carbon
dioxide. Contaminated soil requiring treatment would be excavated
and place in a treatment cell. This cell would be an above-
ground, lined treatment bed. The capacity of a two-acre treatment
cell system is assumed to be 3,200 tons per lift (12-inch lift
depth) and a three month treatment cycle. It is also assumed that
80
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a two-acre area could accept four lifts per year. Based on these
assumptions, the following are the estimated sizes for the
treatment cells to address the volume of contaminated soils
(presented in Table 5-11, in addition to the 5,000 cubic yards of
soil from the Bayou Disposal Area) at the site in a five year
period:
AREA ESTIMATED VOLUME OF ESTIMATED TREATMENT
CONTAMINATED SOILS WEIGHT AREA REQUIRED
(Cubic Yards) (Tons) (Acres)
Main Waste Area
Office Trailer
West Road Area
Easement Area
Bayou Disposal
85,600
71,300
18,500
122,400
5,000
128,186
106,772
27,704
183,294
7,487
4
3.25
0.85
5.75
0.25
The treated soil would be used as backfill material for the
excavated areas of the site. Treatability studies indicated that
biological treatment of benzene, ethylbenzene, xylene, and PNAs
was technically feasible and effective. The remedial levels for
these contaminants can be achieved by biological treatment.
This alternative would comply with the Land Disposal Restrictions
through a Treatability Variance under 40 CFR 268.44. This variance
results in the use of biological treatment to attain the Agency's
interim "treatment level ranges" for the contaminated soil at the
site. If all the "treatment level range(s)" are not met, this
variance will result in the use of biological treatment in
conjunction with solidification/stabilization or other treatment
methods to attain the Agency's interim "treatment level range(s)"
for the contaminated soil at the site.
Closure requirements under RCRA will vary with each technology
considered in conjunction with biological treatment. However, it
is possible that biological treatment will not destroy all
hazardous waste on the site. Therefore, a "landfill" closure may
also be required. The volume of material under the cap will depend
upon the volume reduction afforded by biological treatment.
Applicable RCRA regulations affecting landfill closure require that
the site be capped, with a final cover designed and constructed to
provide long-term protection of human health and the environment
through minimization of the infiltration of liquids through the
capped area and proper maintenance of the integrity of the cap over
time with maintenance. This type of closure anticipates that post
closure care and maintenance will be carried out at the site for
at least 30 years. As previously stated, institutional controls
are not enforceable in the State of Texas and, therefore, are not
considered to be an effective component of the overall remedy.
The alternative would take approximately 5 years to implement, and
the present worth cost of these activities is estimated to be
$41,100,000. EPA does not favor this alternative since in the
81
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short term the mobility of the volatile contaminants will increase
as the soil is excavated.
Alternative 4:
SOLVENT EXTRACTION
Solvent extraction is an innovative technology in which
contaminated soil is excavated and mixed with a clean solvent,
which removes the organic contaminants from the soil. During the
implementation of this remedy, the excavated soils would be stored
on the site in a manner meeting all relevant and appropriate
storage elements until they are fed through the solvent extraction
unit. The treated soil is then separated from the liquid solvent
and used as backfill in the excavated areas of the site.
Contaminated solvents are separated by distillation and shipped
off-site for final disposal by incineration. Clean solvent is
returned to the treatment process.
A treatability study conducted at this site indicated that the
remedial levels set for the contaminants of concern could be
achieved by solvent extraction. This alternative would comply with
the Land Disposal Restrictions through a treatability variance,
resulting in the use of chemical treatment to attain EPA's interim
"treatment level ranges" for the contaminan at the site. Because
the risk-based remedial levels can be achieved, this alternative
would reduce the toxicity of the contaminated soil. By removing
contaminants from the soil and concentrating them in the solvent,
the mobility of the contaminants and the volume of contaminated
material would be reduced. However, at a treatment rate of 15 tons
per day, 300 days per year on-time operation, with a 5-year
treatment period, approximately 20 solvent extractions units would
be needed to treat all the contaminated soils at the site (as
presented in Table 5-11, in addition to the 5,000 cubic yards of
soil from the Bayou Disposal Area).
The generators and transporters of the contaminated solvents would
need t_ meet the Standards Applic e to Generators and
Transporters of Hazardous Waste (40 CFR .rts 262 and 263) since
this alternative involves the generation and off-site
transportation of hazardous waste for disposal.
This alternative would take approximately 5 years to implement, and
the present worth cost of these activities is estimated to be
$142,200,000. EPA does not favor this alternative since it is not
cost effective and the anticipated number of units needed may not
be available.
Alternative 5:
INCINERATION
'ncineration is the controlled combustion of organic waste,
resulting in complete destruction of contaminants. A transportable
82
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incineration facility, consisting of a feed preparation unit, a
thermal destruction unit, a control facility, and fuel storage,
would be built on site. The facility would be operated in
compliance with the technical regulatory standards set for
incinerator performance by the Federal and State governments. Air
emissions resulting from the process would be treated to remove
particulate matter and other gases before being released to the
atmosphere. Water or its equivalent from the air treatment process
would be treated by activated carbon, which would then be removed
from the site for disposal.
During the implementation of this remedy, soils would be excavated
and stored on the site, in a manner meeting all relevant and
appropriate storage elements, until they are fed through the
incinerator. Soil treated in the incinerator would be used as
backfill in the excavated areas of the site. Upon completion of
the remedial action, the incinerator would be dismantled and
removed from the site. Because incineration removes the organic
matter in the soil, it would be helpful to add organic matter, like
straw, to the soil to encourage vegetative growth.
It is expected that all the organic waste above the remedial levels
would be treated below the remedial levels. As previously stated,
the wastes are RCRA wastes, therefore; RCRA regulations on clean
closure would be applicable. These regulations require that all
waste residues and contaminated containment system components be
managed as hazardous waste. These should be removed and/or
decontaminated before the site remediation operations are
completed.
According to RCRA (Section 1004(34)), hazardous waste thermal
destruction units are considered treatment and are, therefore,
subject to several sections in Subtitle C which addresses the
problems of hazardous waste. Subpart 0 of 40 CFR, Part 264,
addresses standards for the operation of hazardous waste thermal
destruction units. This regulation is applicable for this
alternative. This regulation governs applicability, waste
analysis, principal organic hazardous constituents (POHCs),
performance standards, hazardous waste permits and operating
requirements. Similarly, the proposed Standards for Owners and
Operators of Hazardous Wastes Incinerators and Burning of Hazardous
Waste in Boilers and Industrial Furnaces, Federal Register Friday,
April 27, 1990 should be considered in design and treatment
process.
Under the TACB General Rules, 31 TAG Sections 101.20 and 101.21,
control of air pollution from visible emissions and particulate
matter, are ARARs for incineration and establish maximum allowable
levels of particulates in air.
This alternative would take approximately 5 years to implement, and
the present worth cost of these activities is estimated to be
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$280,200,000. EPA does not favor this alternative since this
alternative is not cost effective, and in the short-term, the
mobility of the volatile contaminants would increase as the soil
is excavated.
Alternative 6:
THERMAL STRIPPING
The thermal stripping process consists of excavating and screening
affected soils to remove gravel, and then conveying soils into a
heated, jacketed, trough housing a double-screw mechanism to remove
volatile organics. Volatilization can be assisted by adding steam
or an inert gas as a stripping agent. During the implementation
of this remedy, the excavated soils would be stored on the site,
in a manner meeting all relevant and appropriate storage elements,
until they are fed through the thermal stripping unit. The
contaminated off-gases leaving the thermal unit are carried to a
condenser where the organics are separated into a concentrated
liquid.
There are conditions which limit the range of applicability of this
technology. Affected soil feed has to be friable and more than 20%
solids. Thermal desorption does not remove or stabilize any
metals; however, the metals are generally not oxidized at these
temperatures. Therefore, metals generally do not obtain increased
mobility or leachability after treatment. The solid end-product
is a dry material with less than 1% moisture. This condition can
lead to substantial handling problems due to dust formation;
however, the dust can be controlled by adding moisture and/or using
covered disposal containers.
At a treatment rate of 12 tons per day per unit, 300 days per year
on-time operation, with a 5-year treatment period, 25 thermal
stripping units would be needed to treat all the contaminated soils
(as defined in table 5-11, in addition to the waste in the Bayou
Disposal Area).
The results of treatability studies conducted at sites similar to
Petro-Chemical Systems indicate that the remedial goals set for
benzene can be achieved by thermal stripping. Additional
treatability studies might be needed to optimize the stripping
process to achieve the remedial goals for the other contaminants
of concern. This alternative would comply with the Land Disposal
Restrictions through a treatability variance. The volume,
toxicity, and mobility of the contamination would be reduced by
transferring the contaminants from the soil to a smaller volume of
liquid that is shipped off-site for ultimate disposal.
This alternative would need to meet the Standards Applicable to
Generators of Hazardous Waste (40 CFR Parts 262 and 263) since this
alternative involves the off-site transportation of hazardous waste
for disposal.
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As previously stated, the wastes are RCRA wastes; therefore, RCRA
regulations on clean closure would be applicable. These
regulations require that all waste residues and contaminated
containment system components be managed as hazardous waste. These
should be removed and/or decontaminated before the site remediation
operations are completed.
This alternative would take approximately 5 years to implement, and
the present worth cost of these activities is estimated to be
$121,000,000. EPA does not favor this alternative since, in the
short-term, it is not cost effective, the mobility of the volatile
contaminants will increase as the soil is excavated, and the
anticipated number of units needed may not be available.
Alternative 7:
ON-SITE LANDFILL DISPOSAL
In this alternative, a hazardous waste landfill would be built on-
site in the Main Waste Area. Waste from all areas of the site
would be excavated and consolidated in this area of the site for
disposal in the landfill. The landfill would completely
encapsulate the contaminated soil, providing protection from both
direct contact and the potential for waste to continue
contaminating the ground water. The bottom of the landfill would
be built with a two-layered system to collect any contaminated
water that might filter through the encapsulated waste over time.
The ability of this collection system to capture this water ensures
that the ground water under the landfill will not become
contaminated over time. Collected water would be pumped out of the
system periodically and treated. The landfill would also be built
with a multi-layer cover, similar to the cover discussed in
Alternative 2. This would minimize the potential for rain water
to filter into the landfill and through the encapsulated waste.
This alternative would need to comply with 40 CFR Part 264, Subpart
N, which deals with the disposal of hazardous materials in a
landfill. This alternative would also need to comply with Land
Disposal Restrictions which are applicable for this alternative.
As stated previously, EPA is directed by Federal environmental
regulations to "utilize permanent solutions and alternative
treatment technologies or resource recovery technologies to the
maximum.extent practicable" and to prefer remedial actions in which
treatment "permanently and significantly reduces the volume,
toxicity, or mobility of hazardous substances, pollutants, and
contaminants as a principle element".
This alternative would provide no reduction in the toxicity or
volume of contaminants. In the short-term, the mobility of
volatile contaminants would be increased by excavation. Because
the waste would eventually be encapsulated, some reduction in the
85
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mobility of the contaminants would be provided by this alternative
in the long-term. For this alternative to remain effective in the
long-term, perpetual maintenance of the multi-layer cover and the
components of the collection system would be required. Periodic
treatment and disposal of any contaminated water in the collection
system would also be required.
This alternative would take approximately 1 year to implement, and
the present worth cost of these activities is estimated to be
$27,800,000. EPA does not favor this alternative since it does not
utilize treatment and there would be no reduction in the volume or
toxicity of the contaminants.
Alternative 8:
OFF-SITE LANDFILL DISPOSAL
In this alternative, approximately 302,800 cubic yards of
contaminated soil would be excavated and transported to a permitted
chemical waste landfill off-site. Clean soil would be brought to
the site for use as backfill in the excavated areas. These areas
would then be seeded to provide a vegetative cover and restored to
their original conditions. Long-term monitoring and site
maintenance would not be required.
Although this alternative reduces the risks at the site itself, it
would require the removal and disposal of soil that is contaminated
at levels which may pose health or environmental risks. Therefore,
this alternative may not be implementable due to Federal Land
Disposal Restrictions.
This alternative would need to comply with 40 CFR Part 264, Subpart
N, which deals with the disposal of hazardous materials in a
landfill. Since off-site transportation of hazardous materials
will occur with the alternative, the requirements of 49 CFR Parts
107, 171 - 177, which regulates transportation of hazardous
materials, would need to be met. Land Disposal Restrictions are
also applicable for this alternative and the LDR requirements would
need to be complied with.
The total cost of this alternative is approximately $72,400,000,
and the estimated time required to implement this alternative would
be 1 year. EPA does not favor this alternative since it is not
cost effective, it does not utilize treatment, and there would be
no reduction in the volume or toxicity of the contaminants.
Alternative 9:
VAPOR EXTRACTION and CATALYTIC OXIDATION
Vapor extraction is an innovative in-situ process which uses air
to vaporize contaminants and remove them from the soil. The
proposed vapor extraction process includes both air injection and
air extraction wells. The air injection wells are used to pump air
86
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into the ground beneath the contaminated soil. The air extraction
wells are located in the contaminated soil and pull air through the
network of extraction wells. Barriers can be installed around the
contaminated soil areas to increase the ability of the vacuum
system to extract only air from contaminated zones. A soil and
synthetic liner cap placed over the contaminated areas would also
help to control the amount of air pulled into the system, as well
as minimizing surface water infiltration.
The movement of the air through the soil causes the contaminants
to vaporize and mix with the moving air. The contaminants are then
removed from the soil, without excavation, by collecting the air
in the extraction wells. The collected air is then passed through
a catalytic thermal destruction unit, where catalytic oxidation of
the contaminant-laden air stream takes place. Catalytic oxidation
is a combustion process where the contaminant-laden air stream is
preheated and passed through a catalyst bed. Final products of the
oxidation are typically carbon dioxide, water, and inorganics. The
cleaned air is then released to the atmosphere.
Because the vapor extraction systems removes contaminants without
excavating the soil, the Land Disposal Restrictions are not
applicable to this alternative.
The requirements of TACB Standard Exemption No. 68 will be met.
This exemption states that for soil and ground water stripping the
total emissions of air contaminants (except nitrogen, carbon
dioxide, air, oxygen, and water vapor) should not exceed five
pounds per hour. In addition, for soil stripping, operations would
be conducted at least 1,000 feet from any residence or other
structure or recreational area not occupied or used solely by the
operator of the property on which the operations are conducted.
Treatment would continue until concentrations of contaminants drop
below the remediation levels across the areas. There would be long
term maintenance or monitoring costs for this option, since there
would be materials remaining after treatment.
Treatability studies of vapor extraction systems have been
conducted at sites in Florida and Pennsylvania, with similar soils
to the soils found at the Petro-Chemical Systems, Inc. site. The
results of these studies indicate that vapor extraction with
catalytic oxidation of the extracted vapors can be effective in
reducing the mobility, toxicity, and volume of the contaminants in
mixed clay and sand soils like those at the site.
The present worth cost of these activities is estimated to be
$26,430,000, and the estimated time required to implement this
alternative would be 5 years. operation and maintenance would
continue for an estimated period of 30 years to ensure that the
remedial levels are maintained. This alternative, more so than
other alternatives, greatly reduces the probability of volatile
87
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emissions since excavation is not a large factor. Excavation is
limited to well installation and slurry wall emplacement. This
alternative is cost effective and complies with Federal law calling
for treatment. It also reduces the toxicity, mobility, and volume
of contaminants in the soil, thus reducing the ability of the
contaminants to leach into the ground water. EPA, therefore,
favors this technology.
Ground water Remediation Alternatives
The remediation levels for ground water contamination are the MCLs
and the proposed MCLs for the contaminants of concern. Attainment
of these levels will be protective of human health and the
environment. However, EPA recently studied the effectiveness of
ground water extraction systems in achieving specified goals and
found that it is often difficult to predict the ultimate
concentration to which the contaminants in the ground water can be
reduced. At the site, geologic conditions in some areas (i.e., the
Main Waste Area), such as silty and clayey sands and the presence
of sand stringers, may prevent reaching the remedial levels. The
study did find that ground water extraction is an effective
remediation measure and can achieve significant mass removal of
contaminants. The remedial alternatives described in this section,
except "No Action", include combination ground water extraction
systems and assume that it is technically feasible to achieve MCLs
in the ground water.
The following remedial alternatives to extract the contaminated
ground water have been developed:
Alternative 10: Recovery and Reinjection Wells
Alternative 11: Recovery and Recharge Trenches
These alternatives will be evaluated in combination with the
following alternatives, which have been developed to address the
extracted ground water:
Alternative 12: Off-Site Ground Water Disposal
Alternative 13: On-site Carbon Adsorption Treatment or Vapor
Extraction with Catalytic Oxidation
Common Elements
Except for the no-action alternative, the ground water alternatives
that were considered for the site included a number of common
elements.
Each alternative assumes that the contaminated soil at the Petro-
chemical Systems, Inc. site will be addressed. The effectiveness
of these alternatives depends on the removal of the soil
contaminants as a continuing source of contamination to the ground
water. In the Feasibility Study Report, alternatives were
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developed and evaluated to: 1) extract the contaminated ground
water, and 2) address the extracted ground water.
The ground water alternatives also require that ground water
monitoring during the remedial activities be used to evaluate
performance of the remedial action. Monitoring points are
anticipated in locations upgradient of the plumes (to detect
contamination from other sources), within the plumes (to track the
plume movement during remediation), and downgradient (to detect
plume migration). Ground water samples would be analyzed for site
indicator compounds as determined during the remedial design.
Existing monitoring wells and possibly additional monitoring wells
would be used for ground water monitoring. The specific locations
and frequency of ground water monitoring will depend on the
remedial alternative selected and site conditions at the time of
implementation. Monitoring would continue after remedial
objectives are met to ensure that residual contaminants desorbing
into ground water do not exceed MCLs or proposed MCLs in the
future.
In the State of Texas, the water rights belong to the land owner.
The State has no mechanism to prohibit use of a stream, or ground
water, as such. Therefore, it is particularly important that the
ground water be remediated to protect public health.
As with the soil alternatives, all costs and time required to
implement all of the ground water alternative combinations are
estimates. Table 7-2 summarizes estimated costs and implementation
times for the ground water extraction and treatment alternatives.
The goal of this remedial action is to restore ground water to its
beneficial use. However, due to the low yield of the aquifer in
several source locations on the site, the ability of the extract
and treat systems to effectively reach the remediation goal is
uncertain. The extent of ground water contamination is illustrated
on Figure 5-8. Based on information obtained during the remedial
investigation and subsequent supplemental remedial investigation,
and the analysis of the ground water remedial alternatives, EPA
believes that this goal is attainable. Ground water contamination
may be especially persistent in the immediate vicinity of the
contaminants' source, where concentrations are relatively high.
The ability to achieve cleanup goals throughout the areas of
attainment cannot be determined until the extraction system has
been implemented, modified as necessary, and the plume response
monitored over time. If the selected remedy cannot meet the
remediation goals for the Petro-Chemical Systems, Inc. site
throughout the areas of attainment during the implementation,
contingency measures which will be protective of human health and
the environment, and are technically practicable under the
corresponding circumstances will be implemented.
To determine if the contingency measures are necessary, the ground
89
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POOR QUALITY
ORIGINAL
-------
water extraction systems for the Alternative combinations will be
closely monitored as outlined previously. The monitoring will take
place throughout the implementation of the remedy and the system's
performance will be carefully evaluated. If it appears that the
system cannot attain the remedial goals set for the site,
contingency measures including one, some or all of the activities
below will be implemented:
a) discontinuing operation of extraction wells and/or
trenches in areas where cleanup goals have been attained;
b) alternating pumping at wells to eliminate stagnation
points;
c) establishing an Alternative Concentration Limit ("ACL")
for the contaminants throughout the areas of attainment,
provided compliance with CERCLA Section 121 (d) (2) (B)
(ii) can be demonstrated;
d) waiving the ground water ARAR for portions of the aquifer
based on technical impracticability of achieving further
contaminant reduction;
e) implementing low level pumping as a long-term gradient
control or construction of a containment measure such as
a slurry wall; and/or
f) implementing additional source control treatment to
further reduce contaminant migration to ground water.
Common Ground Water ARARs
Common Chemical specific ARARs that will be met at the site include
the following:
The National Primary Drinking Water Standards establish health-
based standards for public water systems (maximum contaminant
levels, MCLs). MCLs are ARARs at the site since the affected
ground water may be directly used for drinking water.
Sections of the Clean Water Act, Water Quality Criteria (WQC) and
Ambient Water Quality Criteria (AWQC) (40 CFR Part 131) set
criteria for water and ambient water quality based on toxicity to
human health and toxicity to aquatic organisms, respectively. WQCs
and AWQCs for site chemicals are ARARs.
The Drinking Water Standards for Public Water Supply Systems
establish health-based standards for a specific list of
contaminants for public water supply systems. These are identical
to federal standards promulgated under the Safe Drinking Water Act
and are site ARARs.
91
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Under the State of Texas Rules, Surface Water Quality Standards (31
T.A.C Sections 307.1-307.10), establish criteria for surface water
quality, and criteria and control procedures for specific toxic
substances. These are ARARs if the selected alternative calls for
discharge to a surface water.
Common Location Specific ARARs that will be met at the site include
the State of Texas Rules, Ground Water Protection Act (26 T.W.C.
.403-.406). This rule requires ground water to be restored, if
feasible. This is an ARAR because ground water is affected.
Common Action Specific ARARs that will be met at the site include
the Standards for Owners and Operators of Hazardous Waste
Treatment, Storage and Disposal (TSD) Facilities, Subpart I (Use
and Management of Containers), and Subpart J (Tanks). These will
be ARARs for ground water if the selected alternative involves
storage of containers of hazardous waste or would involve the use
of tanks to treat or store hazardous materials.
Under the Safe Drinking Water Act, Underground Injection Control
Regulations (40 CFR Parts 144-147), provide for protection of
underground sources of ground water. This will be an ARAR if
ground water remediation involves injection to enhance remediation.
The specific ARARs that come into play for each alternative will
be included in the description of each alternative.
Alternative 10:
RECOVERY WELLS WITH INJECTION
A recovery well system can be designed to remove contaminated
ground water from an aquifer. The well spacing and pattern are
determined by aquifer characteristics and pumping rates.
Generally, well spacing is set to allow minimal overlap of the
cones of depression. The ability of these wells to remove the
ground water is enhanced by replacing the extracted water with
either water from a clean source or treated water from the site.
Recovered ground water would be pumped from the wells and treated
on-site or disposed of at an off-site deep well injection facility.
The implementation time for this extraction alternative varies from
67 years in the Main Waste Area to two months to restore a small
volume of ground water in a deeper aquifer found near the temporary
office area.
Alternative 11:
RECOVERY TRENCHES WITH INJECTION
Ground water recovery trenches can be installed in strategic
locations around contaminated plumes to intercept the ground water
for treatment or disposal. The trench is backfilled with gravel
or other porous media and is sloped to a collection sump. The
92
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porous media is only placed in the permeable zone and is covered
with backfill. Recovered ground water would be pumped from the
trenches and treated on-site or disposed of at an off-site deep
well injection facility. The ability of these trenches to remove
the ground water is enhanced by replacing the extracted water with
either water from a clean source or allowing treated water from the
site to seep into the ground. This extraction technology has been
successfully used in the Gulf Coast region. The implementation
time for this extraction alternative in the Main Waste area is
estimated as four years.
Alternative 12:
RECOVERY and OFF-SITE GROUND WATER DISPOSAL
In this alternative, contaminated ground water would be recovered
either by pumping from wells or interception in recovery trenches.
All extracted ground water would stored in holding tanks until a
chemical analysis was performed. Based upon the results of the
analysis, the proper disposal method could be selected. Ground
water with concentrations of contaminants that are below discharge
standards for Turtle Bayou or Trinity River, as set by the State
of Texas, would be discharged directly into the bayou or the
Trinity River. Contaminated ground water with concentrations
exceeding discharge standards would be transported to an off-site
deep well injection facility. In some areas of the site, the
presence of polynuclear aromatic hydrocarbons above the standards
set for the bayou and Trinity River would prohibit discharging
directly to Turtle Bayou or the Trinity River.
This alternative would reduce the toxicity, volume, and mobility
of contaminants at the site by removing them from the Petro-
chemical Systems site, but would transfer these characteristics to
the disposal facility.
Based on the analytical results obtained during the RI (LAN, 1990)
and the SRI (WESTON, 1991), in two areas of the site, contaminant
concentrations are within acceptable Turtle Bayou discharge
limitations for the low level lead contaminated ground water in the
shallow permeable zone of the East Disposal Area - East, and the
benzene contaminated ground water in the deep aquifer of the
Temporary Site Office. The discharge limitations from the State
Water Quality Standards (WQS) were obtained from the Texas Water
Commission (See Table 7-3). The technology based NPDES Permit
effluent limitations for hazardous waste treatment facilities for
lead also have been included in the table since they are more
stringent than the state's WQS for lead. The contaminated ground
water in other areas (i.e, Main Waste Area, West Road Area, Office
Area, and Power Easement Area) would be stored in holding tanks,
and transported by tank trucks to be disposed of by deep well
injection.
Under the Solid Waste Disposal Act, the Standards Applicable to
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TABLE 7-3
EFFLUENT LIMITATIONS FOR DISCHARGE
TO TRINITY RIVER AND TURTLE BAYOU
Parameter*
Benzene
Ethylbenzene
Styrene
Toluene
Xylenes, Total
Total Polynuclear Aromatic
Hydrocarbons (PNAs)
Lead *
Discharge to Trinity River
Discharge Limitations
Daily Avg.
ug/1
200
200
100
200
200
150
199
Daily Max
ug/1
400
400
200
400
400
300
275
Discharge to Turtle Bayou
Discharge Limitations
Daily Avg.
ug/1
200
200
100
200
200
0.4
199
Daily Max
ug/1
400
400
200
400
400
0.9
275
* - Technology based NPDES Permit effluent limitations for hazardous vaste
treatment facilities for point source discharge.
Note: The State numerical Hater Quality Standards (WQS) are in-stream limits.
Therefore, it is necessary to calculate the dilution from in-stream
concentrations to the discharge point to determine the appropriate WQS
limit for the effluent.
94
POOR QUALITY
ORIGINAL
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Generators of Hazardous Waste (40 CFR Part 262), establish
standards for generators of hazardous wastes. This would be an
ARAR since this alternative involves the off-site transportation
of ground water for treatment or disposal and would need to be
addressed if this alternative was implemented.
This alternative would take approximately 67 years and cost an
estimated $13,600,000 if the ground water recovery and reinjection
wells are used to extract the contaminated ground water. This
alternative would take approximately 4 years and cost approximately
$40,400,000 if recovery and recharge trenches are used to extract
the contaminated ground water. EPA does not favor this alternative
since it would not satisfy the preference for treatment in the
Superfund law.
Alternative 13: RECOVERY and ON-BITE CARBON ABSORPTION or VAPOR
EXTRACTION with CATALYTIC OXIDATION
In this alternative, all extracted ground water would be stored in
holding tanks until a chemical analysis was performed. Based upon
the results of the analysis, the proper disposal method could be
selected. Ground water with concentrations of contaminants that
are below discharge standards set for Turtle Bayou by the State of
Texas would be discharged directly into the bayou. This might
include contaminated ground water from the deeper aquifer in the
area of the temporary site office. Contaminated ground water from
the other areas of the site would be recovered and treated by
either carbon adsorption or catalytic oxidation. If the treated
water did not meet the discharge requirements for Turtle Bayou, it
would have to be discharged off-site. This water should meet the
discharge requirements for the Trinity River north of the City of
Liberty.
The vapor extraction with catalytic oxidation treatment alternative
is included with the carbon absorption treatment alternative, even
though the specific overall analysis has not been conducted for
the catalytic oxidation alternative. Since soil alternative 9,
soil vapor extraction with catalytic oxidation, is the EPA selected
soil alternative, we expect that the overall cost for using the
catalytic oxidation treatment alternative for ground water would
be lower than carbon adsorption since some of the costs associated
with using this technology for ground water would already be
included in the cost of the soil alternative (i.e, cost of the
catalytic oxidation unit). If the ground water contaminants cannot
be removed by the vapor extraction process, then the contaminated
ground water would need to be extracted by recovery wells and/or
trenches. These are costs that would also be included in the
carbon adsorption alternative. Since a pilot study is planned for
this alternative during the remedial design, it is a logical step
to determine the implementability, protectiveness, and specific
costs associated with using this technology to treat the
contaminated ground water during the pilot study. If it is
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determined that the catalytic oxidation alternative can meet the
ground water remedial levels and is more or equally cost effective,
protective, and implementable than alternative ground water
treatment technologies, such as carbon adsorption, the catalytic
oxidation ground water alternative will be used. Otherwise, an
alternative treatment technology, such as carbon adsorption, would
be used.
In the carbon adsorption process, contaminants are removed from the
water by adsorbing on to the carbon in a treatment unit. The toxic
materials are retained on the carbon. The contaminants on the
carbon can then be thermally destroyed (on or off site), recycled
or landfilled. As the waste is a RCRA hazardous waste, disposal
of the carbon in compliance with RCRA hazardous waste regulations
would be necessary.
In the vapor extraction with catalytic oxidation process, the
contaminated ground water would be treated just like the
contaminated soil. The contaminants would be removed from the
ground water by vapor extraction and destroyed in the catalytic
oxidation unit. The ability of vapor extraction to remove the
volatile contaminants from the ground water would be determined
during the Remedial Design. If vapor extraction cannot remove the
volatile contaminants ^n the ground water to meet the remedial
levels, extracting the ground water by the use of wells and/or
trenches and then running the water though an air stripper, might
be an option to remove the contaminants from the ground water. The
contaminants from the ground water, now in the vapor phase, would
be destroyed in the catalytic oxidation unit. The efficiency of
the contaminant removal will be investigated during a pilot study.
As with the treated soil vapor, the appropriate NESHAP, Clean Air
Act, and Texas Rules for air emissions would need to be addressed.
Extracted ground water, once treated, would be either reinjected
or discharged to Turtle Bayou or the nearby Trinity River.
Treatment of the contaminated ground water by either carbon
adsorption or by catalytic oxidation will be evaluated in greater
detail during the remedial design. At that time, the selection or*
whether to use carbon adsorption or catalytic oxidation to treat
the contaminated ground water will be made.
Under the State of Texas Rules, the Surface Water Quality Standards
(31 T.A.C Sections 307.1-307.10), establish criteria for surface
water qual ty and criteria and control procedures for specific
toxic subs ances. These are ARARs, since this alternative calls
for discharge to a surface water, and they will need to be
addressed.
Alternative 13 would take approximately 67 years and cost an
estimated $3,450,000 if the ground water recovery and reinjection
wells are used to extract the contaminated ground water. This
alternative would take approximately 4 years and cost approximately
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$3,240,000 if recovery and recharge trenches are used to extract
the contaminated ground water. Alternative 13 would reduce site
risks by restoring the ground water for potential drinking water
usage. It would also comply with federal and state environmental
laws and the Superfund preference for treatment. For these
reasons, EPA does favor this alternative.
Note: The costs presented for this alternative were calculated for
treatment of the contaminated ground water by using carbon
adsorption. The specific costs associated with using vapor
extraction with catalytic oxidation have already been included in
soil remediation Alternative 9. This was done since some of the
costs (i.e., the purchase and setup cost for the catalytic
oxidation units) are already included in EPA's preferred soil
alternative, Alternative 9 - Soil Vapor Extraction and Catalytic
Oxidation.
VIII. SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES
The U.S. EPA uses nine criteria, or standards, to evaluate
alternatives for addressing a Superfund site. These nine criteria
are categorized into three groups: threshold, primary balancing,
and modifying. The threshold criteria must be satisfied in order
for an alternative to be eligible for selection. The primary
balancing criteria are used to weigh major tradeoffs among
alternatives. The modifying criteria are taken into account after
public comment is received on the Proposed Plan of Action.
The nine (9) criteria used in evaluating all of the alternatives
identified are as follows:
THRESHOLD CRITERIA
Overall Protection of Human Health and Environment addresses the
way in which a potential remedy would reduce, eliminate, or control
the risks posed by the site to human health and the environment.
The methods used to achieve an adequate level of protection may be
through engineering controls, treatment technique*, or
controls such as restrictions on the future
use of the site. Total elimination of risk
is often impossible to achieve. However, a
remedy must minimize risks to assure that
human health and environment are be protected.
Compliance with ARARs. or "applicable or relevant and appropriate
requirements," assures that a selected remedy will
meet all related federal, state, and local
requirements. The requirements may specify maximum
concentrations of chemicals that can remain at the
site; design or performance requirements for
treatment technologies; and restrictions that may limit
potential remedial activities at a site because of its location.
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PRIMARY BALANCING CRITERIA
LongTerm Effectiveness and Permanence address the
ability of a potential option to reliably protect
human health and the environment over time, after
the remediation goals have been accomplished.
Reduction of Toxicitv. Mobility, or Volume of Contaminants assess
how effectively a proposed remedy will address the
contamination problem. Factors considered include
the nature of the treatment process; the amount of
hazardous materials that will be destroyed by the
treatment process; how effectively the process
reduces the toxicity, mobility, or volume of waste; and
the type and quantity of contamination that will remain after
treatment.
Short-Term Effectiveness addresses the time factor. Remedies often
require several years for implementation. A
potential remedy is evaluated for the length of time
required for implementation and the potential impact
on human health and the environment during
implementation.
Implementabilitv addresses the ease with which a potential remedy
is put in place. Factors such as availability of
Q materials and services are considered.
Cost (including capital costs required for design
and construction, and projected long-term mainten-
ance costs) is considered and compared to the
benefit that will result from implementing the remedy.
MODIFYING CRITERIA
State Acceptance
OKI
The state has the opportunity to review the
RI/FS, the SRI/FFS, and the Proposed Plan and
offer comments to the U.S. EPA. The state may
agree with, oppose, or have no comment on the
U.S. EPA preferred alternative.
Acceptance During the public comment
period, interested persons or organizations may
comment on the potential remedies. U.S. EPA
considers these comments in making its final
selection. The comments are addressed in a
document called a responsiveness summary, which
is part of this record of decision for the site (Appendix A)
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A ranking of the comparative analysis for the soil remedial
alternatives is included (see Table 8-1). The symbolic ranking is
based on the narrative analysis that follows.
ANALYSIS OF SOURCE CONTROL ALTERNATIVES
Criterion 1: Protection of Human Health and Environment
The "No Action" alternative offers no additional protection from
the site risks defined in the Risk Assessment. Because the "No
Action" alternative is not protective of human health and the
environment, it will not be discussed further. Alternatives 2 and
7, the "Slurry Wall with Cap" and "On-Site Landfill" alternatives,
would provide similar levels of protection through engineering
controls, but would require perpetual maintenance to ensure
protection. In addition, the risks associated with the contaminated
ground water within the slurry wall would still exist.
Alternative 3, "Biological Treatment", would provide protection by
reducing the risks associated with the site contaminants by
treatment; however, the ability of biological treatment to degrade
polynuclear aromatic hydrocarbons, which do not degrade easily, is
questionable. Alternative 4, "Solvent Extraction", would provide
protection through extracting the contaminants from the soils by
adding a chemical solvent, separating the contaminants from the
solvent, and shipping the contaminants off-site for disposal, thus
reducing the site risk. Alternative 5, "Incineration", provides
protection by destroying the non-metal contaminants on the site
below the health-based criteria. The risks associated with the
metal contaminants would still remain. Alternative 6, "Thermal
Stripping", provides protection by vaporizing the volatile and
semi-volatile contaminants and condensing the vapors into a liquid
which is disposed of off-site. Alternative 8, "Off-Site Landfill",
would provide protection at the site by removing the contaminants
off the site. The risks associated with the contaminants would
still remain. Alternative 9, "Vapor Extraction and Catalytic
Oxidation", provides protection by extraction of the contaminants
from the soil and the destruction of the contaminant laden vapor
by catalytic oxidation.
Criterion 2; Compliance with Applicable Relevant and Appropriate
Requirements fARARs)
ARARs are the Federal and State requirements that a selected remedy
must meet. For example, since the eastern portion of the site is
located in a floodplain (see Figure 1-4), floodplain ARARs outline
restrictions that apply for building within the floodplain. As
previously discussed, this site does contain RCRA hazardous wastes.
Therefore, alternatives 3-8, which involve extraction and placement
of RCRA hazardous waste, will need to comply with Land Disposal
Restrictions (LDRs), ARARs for placement of hazardous waste in a
landfill, surface impoundment, waste pile, or land treatment
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TABLE 8-1
COMPARATIVE ANALYSIS FOR SOIL REMEDIAL ALTERNATIVES
Petro-Chemical Systems, Inc.
CRITERION
ALTERNATIVE
Overall Protection of Human Health
and the Environment
Most Protective
Alt. 5
Alt. 4, Alt. 6, Alt. 9
Alt. 3
Alt. 2, Alt. 7, Alt. 8
Least Protective
Compliance with Applicable and
Relevant and Appropriate
Requirements (ARARs)
All alternatives will
comply with the
appropriate ARARs
Long-Term Effectiveness
Most Effective
Alt. 5
Alt. 4, Alt. 6, Alt. 9
Alt. 3
Alt. 2, Alt. 7, Alt. 8
Least Effective
Reduction of Toxicity, Mobility,
or Volume through Treatment
Most Reduction
Alt. 5
Alt. 9
Alt. 4, Alt. 6
Alt. 3
Alt. 2, Alt. 7, Alt. 8
Least Reduction
Short-term Effectiveness
Alt.
Most Effective
Alt. 2
Alt. 7, Alt. 8
Alt. 9
3, Alt. 4, Alt. 5, Alt. 6
Least Effective
Implementability
Simplest to Implement
Alt. 2
Alt. 7, Alt. 8
Alt. 3, Alt. 5, Alt. 9
Alt. 4, Alt. 6
Hardest to Implement
Costs
Least Costly =>
Alt. 2, Alt. 9, Alt. 7, Alt. 3, Alt. 8,
Alt. 6, Alt. 4, Alt. 5 <- Most Costly
100
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facility unit, as appropriate. Alternatives 3, 4, and 6 would
comply with the LDRs through a treatability variance, resulting in
the use of treatment to attain EPA's interim level ranges for the
contaminants until the final treatment level ranges are reached at
the site. Alternative 5 would comply with all the ARARs associated
with incineration. This would include 40 CFR Part 264, subpart O,
which addresses standards for operation of hazardous waste thermal
destruction units. The containment and landfill alternatives
(alternatives 2, 7, & 8) would comply with the ARARs appropriate
to those remedies. Alternative 9 would not need to comply with
the LDRs since this alternative does not involve the placement of
hazardous waste. Alternative 9 would need to comply with the
applicable or relevant and appropriate regulations for air
emission, including the requirements of TACB Standard Exemption 68.
Each alternative has been reviewed in the "Description of
Alternatives" section of this document for ARARs.
Criterion 3; Loncr-Term Effectiveness and Permanence
Solvent extraction, thermal stripping, and incineration remove and
ultimately destroy the contaminants at the site. Final
concentrations would be below the remedial criteria set for
protection of the ground water. Vapor extraction with catalytic
oxidation will also remove and destroy the organic contaminants at
the site. Biological treatment will reduce the concentration of
benzene to the remedial level; however, polynuclear aromatic
hydrocarbon concentrations may not be sufficiently reduced.
Containment, on-site and off-site land disposal will minimize the
potential for future ground water contamination by encapsulating
the waste (alternatives 2, 7 & 8). However, containment, on-site
and off-site land disposal will not meet the remedial goals
established for the site soils or ground water. On-site
containment options will require perpetual maintenance to ensure
that there is no further migration and potential exposure to site
contaminants. On-site containment of lead, a component of all
alternatives except off-site landfill disposal, will result in a
minimal residual risk at the site posed by the isolated areas of
lead contamination. The containment area will require long-term
maintenance to ensure that the isolated lead contamination is not
continuing to act as a potential source of risk to human health or
the environment.
Criterion 4; Reduction of Toxicitv. Mobility, or Volume through
Treatment
The incineration alternative is capable of greater than 99%
destruction of organic waste. Solvent extraction, thermal
stripping, and vapor extraction with catalytic oxidation can reduce
the toxicity of the contaminated soil to acceptable levels, but not
to the same degree as incineration. Biological treatment will
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reduce the concentration of benzene'to the remedial level; however,
polynuclear aromatic hydrocarbon concentrations may not be
sufficiently reduced. All of the treatment alternatives
(alternatives 3, 4, 5, 6, and 9) will ultimately reduce the
toxicity and volume of the contaminants; however alternatives 3-
6 require excavation of contaminated soils which will increase the
short-term mobility of the volatile contaminants by allowing them
to vaporize into the atmosphere. Alternative 9, vapor extraction
with catalytic oxidation, can remove and destroy the organic
contaminants in the site soils without the need for excavation.
The slurry wall and cap, on-site landfill disposal, and off-site
land disposal (alternatives 2, 7, and 8) do not involve treatment
processes. Therefore, these alternatives fail to meet this
criteria and will not result in a reduction of toxicity, mobility,
or volume through treatment.
Criterion 5; Short-Term Effectiveness
The slurry wall and cap alternative is the most attractive
alternative based solely on short-term effectiveness. This
alternative would require the least amount of contaminant
excavation and transportation and would take approximately one year
to implement. Also, the slurry wall could be installed in
essentially uncontaminated areas. Both on-site and off-site
landfill disposal alternatives would require approximately one year
to implement, however, the on-site landfill disposal alternative
might not rear ire the RCRA vault to be dismantled. The remaining
alternatives ould each require approximately five years to
implement. Alternatives that do not require excavation of
contaminated soils (alternatives 2 and 9) are favored over those
in which excavation would be required (alternatives 3, 4, 5, 6, 7,
and 8) . This is due to the increased potential for worker
accidents during the excavation activities, as well as the
potential for fugitive emissions resulting during the excavation
of the soils containing volatile contaminants (i.e, benzene).
Alternatives that do not require off-site transport of contaminants
(alternatives 2, 3, 5, 7, and 9) are favored over those
alternatives (alternatives 4, 6, and 8) that require the off-site
transportation of contaminants, due to the potential for traffic
accidents during transport.
In order to minimize short-term risk, community protection will be
provided by air quality monitoring and engineering controls to
regulate air emissions produced by excavation and on-site treatment
processes. This would be done by capturing the emissions from the
treatment units and providing air treatment prior to release to the
atmosphere. Dust control may also be necessary during excavation
and can be accomplished with water or foam sprays.
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Criterion 6: Implementability
The slurry wall and cap alternative is the easiest alternative to
implement; however, some difficulties may be encountered in tying
the slurry wall into the clay layer that separates the shallow
aquifer from the lower aquifer in some parts of the site.
Construction of a cap or a landfill would not present any
particular difficulties at this site. The off-site landfill
alternative is also easily implementable. The landfill
alternatives would need to comply with the Land Disposal
Restrictions. Solvent extraction and biological treatment are
considered innovative technologies for this type of waste.
Treatability studies conducted with waste from the Petro-Chemical
Systems indicate that solvent extraction can achieve all remedial
levels set for the site. The ability of the biological treatment
alternative to achieve the remediation levels for polynuclear
aromatic hydrocarbons is uncertain. The vapor extraction with
catalytic oxidation and thermal stripping alternative is also
considered innovative technologies and would require pilot scale
studies to determine design criteria. As discussed in the
"Description of Alternatives" section, both the solvent extraction
and thermal desorption alternatives would require an estimated 20
and 25 treatment units, respectively, to meet the 10"6 risk goal in
five years. It may be difficult to acquire this number of
treatment units or to obtain larger units to do the job. The
incineration alternative has proven difficult to implement at other
Superfund sites due to the complexities involved and may be
difficult to implement at this site.
Criterion 7; Cost
The estimated costs for the source control remedial alternatives
range from $1.44 million for the "No Action" alternative to $280
million for on-site incineration. Table 7-1 contains the estimated
capital cost, operation and maintenance cost, and the present worth
cost for each source control alternative. The least expensive
source control alternative that provides treatment of the
contaminants is the vapor extraction with catalytic oxidation
alternative. Therefore, vapor extraction with catalytic oxidation
is preferred over the biological treatment, solvent extraction, and
thermal stripping alternatives in reference to the implementation
cost.
Criterion 8; State Acceptance
The State of Texas, through the Texas Water Commission, concurs
with the remedy selected by EPA. (Attachment B)
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Criterion 9; Community Acceptance.
EPA solicited input from the community on the remediation
alternatives proposed to address the source control and ground
water contamination at the site. Judging on the comments received
during the public comment period, the community supports the vapor
extraction with catalytic oxidation alternative to address both
soil and ground water contamination at the site. The preference
for off-site landfill disposal was also voiced.
Comments were received regarding the consolidation of lead
contaminated soils in the Bayou Disposal Area. In light of these
comments, EPA will not be consolidating the lead contaminated soils
in the Bayou Disposal Area, but instead, the isolated areas of lead
contaminated soils will be consolidated in the Main Waste Area
prior to capping. This modification to the proposed plan will be
further discussed in section XI, "Documentation of Significant
Differences."
All comments received during the public comment period and EPA
responses are in the attached Responsiveness Summary (Appendix A).
ANALYSIS OF GROUND WATER ALTERNATIVES
The combination of ground water extraction and disposal/treatment
alternatives will be discussed, as appropriate. As represented in
Table 8-2, the combinations are:
12a. Recovery and Off-Site Ground Water Disposal w/
Recovery and Reinjection Wells
12b. Recovery and Off-Site Ground Water Disposal w/
Recovery and Reinjection Trenches
13a. Recovery and On-Site Carbon Adsorption or Catalytic
Oxidation w/ Recovery and Reinjection Wells
13b. Recovery and On-Site Carbon Adsorption or Catalytic
Oxidation w/ Recovery and Reinjection Trenches
Criterion 1; Protection of Human Health and Environment
The "No Action" alternative offers no additional protection from
the site risks defined in the Risk Assessment. Because the "No
Action" alternative is not protective of human health and the
environment, it will not be discussed further.
The magnitude of the on-site risk is minimal after remediation is
completed using alternative 12. This alternative would provide
protection to human health and the environment at the site by
removing the contaminated ground water from the site and dis-
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TABLE 8-2
COMPARATIVE ANALYSIS FOR GROUND WATER ALTERNATIVES
Petro-Chemical Systems, Inc.
CRITERION
ALTERNATIVE
Overall Protection of Human Health
and the Environment
Most Protective
Alt. 12, Alt. 13
Least Protective
Compliance with Applicable and
Relevant and Appropriate
Requirements (ARARs)
Most Compliance
Alt. 13
Alt. 12
Least Compliance
Long-Term Effectiveness
Most Effective
Alt. 13
Alt. 12
Least Effective
Reduction of Toxicity, Mobility,
or Volume through Treatment
Most Reduction
Alt. 13
Alt. 12
Least Reduction
Short-term Effectiveness
Most Effective
Alt. 12b, Alt. 13b
Alt. 12a, Alt. 13a
Least Effective
Implementability
Simplest to Implement
Alt. 12
Alt. 13
Hardest to Implement
Costs
Least Costly
Alt. 13
Alt. 12
Most Costly
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ORIGINAL
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charging this water into Turtle Bayou (if contaminant concen-
trations do not exceed the discharge standards set by the State of
Texas) or transporting the contaminated ground water to an off-
site deep well injection facility. Due to the removal of the
contaminated ground water, there are no treatment residuals, and
the untreated ground water will have contaminant concentrations
less than those required by the risk assessment. This alternative
meets the requirements set through the target remediation levels.
Because the contaminated ground water is removed from the site,
there is a very high degree of confidence that the alternative will
adequately handle long-term risks.
Alternative 13 would also provide protection to human health and
the environment by removing the contaminated ground water from the
site and discharging this water in Turtle Bayou (if contaminant
concentrations do not exceed the discharge standards set by the
State of Texas) or by treating the contaminated ground water by
either carbon adsorption or running the water through an air
stripper and destroying the contaminants in the contaminant-laden
vapor by catalytic oxidation. The carbon adsorption process uses
activated carbon to remove contaminants from the water. The
activated carbon removes contaminants until the point of
exhaustion. Once this breakthrough point is reached, no more
contaminants are removed from the water and the activated carbon
is either regenerated or disposed of at a licensed treatment/dis-
posal facility. The catalytic oxidation process uses an air
stripping tower to remove the contaminants from the water into a
vapor phase. The contaminated vapors would be destroyed by running
the vapor through the catalytic oxidation unit. Once the ability
of the catalyst to destroy the contaminants is exhausted, the
catalyst would need to be disposed of at a licensed
treatment/disposal facility. The effluent from both of these
treatment systems meets the remedial goals. As with alternative
12, because the contaminants in the ground water are
removed/destroyed, there is a very high degree of confidence that
the alternative will adequately handle lorq-term risks.
Criterion 2; Compliance with Applicable Relevant and Appropriate
Requirements CARARs)
ARARs are the federal and state regulatory standards that a
selected remedy must meet. Alternatives 12 and 13 will meet the
discharge standards set for Turtle Bayou or Trinity River, as
necessary. Even though alternative 12 involves no treatment
components, in some areas of the site, the levels of ground water
contamination are such that if the water is extracted from the
subsurface, it could be discharged directly into the Trinity River
or into Turtle Bayou.
EPA is directed by SARA to "utilize permanent solutions and
alternative treatment technologies or resource recovery
technologies to the maximum extent practicable" and to prefer
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remedial actions in which treatment "permanently and significantly
reduces the volume, toxicity, or mobility of hazardous substances,
pollutants, and contaminants as a principle element". Since
alternative 13 involves treatment, it is preferred over alternative
12 in which no treatment is involved.
Criterion 3: Lona-Term Effectiveness and Permanence
Since alternatives 12 and 13 involve the removal of contaminated
ground water, the magnitude of the on-site risk is minimal after
remediation. Because the source of future contamination, the soil
at the site, will be addressed, the ground water should not become
recontaminated. The adequacy and reliability of the recovery
technologies have been well proven; however, the recovery rates may
not be constant over time given the low ground water yield in some
areas of the site. It may be necessary, over the course of time,
to alter the recovery system to improve the efficiency of the
remedy. Alternative 13 involves treating the waste and thus
reducing the risks associated with the waste in the long-term.
Thus, alternative 13 is preferred over alternative 12 which
involves no treatment.
Criterion 4; Reduction of Toxicitv. Mobility, or Volume Through
Treatment
Alternatives 12a and 12b do not involve treatment processes.
Alternative 13a, on-site carbon treatment, meets EPA's preference
for treatment to reduce the toxicity, mobility, and/or volume of
contaminants. Typical carbon adsorption units used to treat
organic compounds in ground water are capable of reducing influent
concentrations by 99+ percent. Contaminants adsorbed will be
desorbed off site and treated accordingly. This results in a
significant reduction of BTEX and PNA compounds present in the
ground water. No chemicals are used at any of the stages of this
alternative, so there are no additional residues other than spent
carbon.
Alternative 13b, catalytic oxidation of stripped water vapors,
meets EPA's preference to reduce the toxicity, mobility, and/or
volume of contaminants. The principals that apply to the treatment
of the contaminated soils by catalytic oxidation are the same for
ground water treatment. Basically, the contaminants would be
removed from their current media, ground water, and placed in a
vapor phase which would in turn be run through the catalytic
oxidation unit. Catalytic oxidation is a combustion process where
the contaminant-laden air stream is preheated and passed through
a catalyst bed. Final products of the oxidation are typically
carbon dioxide, water, and inorganics.
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Criterion 5; Short-Term Effectiveness
For alternative 12, risks to the community during remediation will
be controlled by the closed removal system. Contaminated ground
water will be transported in tanker trucks or piped for direct
discharge. Some risk to the community will be associated with this
transportation, but should be mitigated by strict compliance with
transportation ARARs. Risk to the remediation workers will be
limited to those associated with initial installation of the
removal system. The risks will be minimized and managed through
OSHA-required health and safety procedures.
For alternative 13, the carbon adsorption option, the steps
involved in treating contaminated ground water by carbon adsorption
include removal of ground water, pumping to a holding tank, and
treating in a carbon adsorption treatment unit. Both the holding
tanks and treatment units would be enclosed in a fenced area and
should not create any undesirable environmental impacts. No
special safety equipment is needed for the operators on site due
to potential failure of the components. Applicable OSHA
regulations will be followed to protect the workers involved in the
construction and operation of the system.
For the vapor extraction with catalytic oxidation option of
alternative 13, a pilot study would be conducted to determine the
efficiency of the removal of contaminants from the ground water.
As with the carbon adsorption treatment option, all appropriate
ARARs, including those dealing with the emissions from the
catalytic oxidation unit, will be followed to prevent the creation
of any undesirable environmental impacts.
Alternatives utilizing extraction and recharge trenches, 12b and
I3b, which require an estimated 4 years to implement, are favored
over alternatives 12a and 13a using extraction and recharge wells
which require an estimated 67 years to implement.
Criterion 6; Implementabilitv
Recovery and recharge trenching are as equally implementable as
recovery and reinjection wells. Trenches should be used in areas
where the yield capacity of the aquifer is low. In areas with a
greater yield capacity or in the deeper aquifer, recovery wells
should be used. The deep well injection disposal and the on-site
carbon adsorption alternatives are equally implementable. A pilot
study for vapor extraction with catalytic oxidation would be
conducted in the Remedial Design to determine the efficiency of the
removal of contaminants from the ground water using this option.
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Criterion 7: Cost
Table 7-2 contains the estimated capital cost, operation and
maintenance cost, and the present worth cost for each ground water
alternative. Please note, the costs presented for alternative 13
were calculated for treatment of the contaminated ground water by
using carbon adsorption. The specific costs associated with using
catalytic oxidation will be determined during the remedial design.
However, some of the costs (i.e., purchase and setup costs for the
catalytic oxidation units) are already included in EPA's preferred
soil alternative, Alternative 9 - Soil Vapor Extraction and
Catalytic Oxidation.
Criterion 8; State Acceptance
The State of Texas, through the Texas Water Commission, concurs
with the remedy selected by EPA. (Attachment B)
Criterion 9; Community Acceptance
EPA solicited input from the community on the remediation
alternatives proposed to address the source control and ground
water contamination at the site. Judging on the comments received
during the public comment period, the community supports the vapor
extraction with catalytic oxidation alternative. All comments
received during the public comment period and EPA responses are in
the attached Responsiveness Summary (Appendix A).
IX. SELECTED REMEDY
Based on consideration of the requirements of CERCLA, the detailed
analysis of alternatives, and public comments, the EPA has
determined that a combination of the various source control and
ground water alternatives at the various contaminant locations on
site will best provide an overall remedy that is protective of
human health and the environment.
Common Elements:
1. Site preparation and installation of office, storage, and
security facilities;
2. Installation of structures to control surface water run-
on/runoff;
3. Monitoring ground water;
4. Dismantling of the RCRA vault with a determination and
(if warranted) remedial action for the potentially
contaminated soils underlying the vault;
5. Consolidation of lead contaminated soils in the Main
Waste Area followed by capping; and
6. The restoration of the site surface upon completion of
the remedial action.
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The site soils remedy is made up of the following six components:
For the Main Waste Area, the RCRA Vault within the Main Waste
Area, the Office Trailer Area, the West Road Area, and the
Easement Area -
ALTERNATIVE 9
1. Soil vapor extraction to remove volatile organics from
affected soils;
2. Vapor collection and transport system;
3. Air injection below affected soils to enhance removal of
volatile organics;
4. Catalytic thermal destruction of volatile organics;
ALTERNATIVE 2
5. Vertical infiltration control by an engineered soil and
synthetic liner cap; and
For the Bayou Disposal Area -
6. Vertical infiltration control by engineered soil and
synthetic liner cap.
A schematic of the soil vapor extraction with catalytic oxidation
of extracted vapors alternative for the Main Waste Area is
presented in Figure 9-1.
The site ground water remedy is made up of the following five
components for the Main Waste Area, Office Trailer Area, West Road
Area, Easement Area:
Alternative 13
1. Removal of volatile organic contaminants from ground
water using vapor extraction (in-situ air stripping);
2. Vapor collection and transport system;
3. Catalytic thermal destruction of volatile organics.
ALTERNATIVE 2
4. Horizontal migration control via slurry wall.
The west side of the East Disposal Area and the deep aquifer
beneath the Temporary Site Office Area will be resampled during the
Remedial Design. The limited data on these areas indicate
contaminants are near the remedial levels for the various
contaminants (i.e. lead, benzene). Based on current sample
analysis data, if ground water from these areas was extracted, this
ground water would already be below the discharge standards for
surface water (See Table 9-1).
Based on the results of this sampling during the Remedial Design,
a determination will be made whether or not remedial action is
necessary for ground water in the two areas. If remedial action
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NUUKh y-1
SOIL VAPOR EXTRACTION WITH CATALYTIC
OXIDATION OF THE. EXTRACTED VAPOR
EXTENT OF SOILS
WITH BENZENE
>10 ABOVE 10 FT.
XX 35 BELOW 10 FT
MAIN
WASTE
AREA
TEMPORARY
SITE OFFICE
MW08
K
MW07
EXTENT OF
COVER
W37 MW19
APPROXIMATE EXTENT OF
GROUNDWATER WITH BENZENE
XX005 mg/L AND LOCATION
OF SLURRY WALL
Y//////X///////,
SHALLOW WATER
BEARMG ZONE
LOWER CLAY
SLURRY WALL
2" SOIL COVER
SYNTHETIC IMPERMEABLE LINER
GEOFABRIC
LEGEND;
0 WESTON SHALLOW MONITORING WEIL
© LAN SHALLOW MONITORING WELLS
^ LAN DEEP MONITORING WELLS
© EXTRACTION WELLS
INJECTION WELLS
COVER
200
=»
SCALE IN FEET
400
111
POOR QUALM
-------
TABLE 9-1
GROUND WATER SAMPLES
REMEDIATION LEVELS - DISCHARGE LIMITATIONS
SAMPLE SAKPLXHG DATE
MW12R
HH12R
MW52
06/26/89
04/30/91
03/23/91
SAMPLE SAMPLING DATE
Summersill
MH19
MW19
03/89
02/13/90
05/03/91
Trinity Riv«r
Discharge
Limitation*
Turtle Bayou
Discharge
Limitation*
BENZENE
(U9/D
ETRLYBENZENE
(uq/1)
XYLENES (Total)
(ug/i)
NAPHTHALENE
(»g/i)
LEAD
(ug/1)
SAMPLE RESULTS PROM EAST SIDE OF EAST DISPOSAL AREA - SHALLOW
< 2
3.5
< 5
< 3
< 5
< 5
< 6
< 5
< 5
< 20
< 11
M.4
IS
< 2
SAMPLE RESULTS FROM TRAILER AREA (DEEP [100<]> AQUIFER
1700 *
7
< 5
< 5
< 9
< 5
< 5
NA
KA
< 3
SITE GROUND WATER REMEDIAL LEVELS
5
700
10,000
327
15
EFFLUENT LIKZTATIOM8 FOR DISCHARGE TO TRINITY RIVER AND TURTLE BAYOU
Dally Avg.
Daily Max
Daily Avg.
Daily Max
200
400
200
400
200
400
200
400
200
400
200
400
Total PNAS 150
Total PNAa 300
Total PMAa 0.4
Total PNAa 0.9
199
275
19»
275
NA - Not Analysed < - Below Sample Detection Limit
* - Nell had been installed without being grouted in place (Well was subsequently removed and grounted)
112
POOR QUALITY,
ORIGINAL
-------
is necessary, the following will be implemented:
5. Extract by extraction wells and/or trenches and store the
contaminated ground water in surface tanks. The water
in the tanks would be sampled and if the samples
indicated contaminant levels above discharge levels, the
water would be treated to below discharge levels. If the
samples showed levels of contaminants below the discharge
levels, the water would be discharged.
The selection of this site remedy is based upon the comparative
analysis of alternatives presented above, and provides the best of
tradeoffs with respect to the nine evaluation criteria. As pointed
out in the comparative analysis, vapor extraction with catalytic
oxidation is the only treatment technology that does not require
the excavation of contaminated soils prior to treatment, thus
reducing the potential for fugitive air emissions of volatile
contaminants such as benzene during excavation. By including the
containment alternatives, cap and slurry wall, as part of the
site's overall remedy, the efficiency of the vapor extraction
system will be improved and current migration of contaminants will
be minimized. The efficiency of the vapor extraction will be
improved by installation of caps over the active treatment areas.
These caps will reduce the amount of air coming from the surface,
so that the air being pulled though the contaminated soils will be
primarily coming from the air injection wells. The cap will also
minimize direct contact exposure and will minimize the amount of
surface water (50+ inches of rainfall/year) coming in contact with
the contaminated soils, thus removing the primary driving force for
contaminants in the soil to migrate into the ground water. The
slurry wall will be tied into the thick clay layer beneath the
shallow water-bearing zone and around each active treatment area.
These slurry walls will minimize the continuing migration of
contaminated ground water prior to treatment by the vapor
extraction (in-situ air stripping) with catalytic oxidation system.
The selected site remedy is implementable and will reduce the
mobility, toxicity, and volume of the contaminants in the site
soils and ground through a combination of treatment and
containment. The selected site remedy is also the most cost
effective alternative of all the treatment technologies evaluated.
The site's selected remedy, in-situ soil and ground water vapor
extraction/air stripping and treatment of extracted vapors by
catalytic oxidation is estimated to take a period of five years.
This will be implemented in the Main Waste Area, Office Trailer
Area, West Road Area, and the Power Easement Area since elevated
levels of volatile organic compounds were found in these areas.
If the selected remedy cannot meet the remediation goals for the
Petro-Chemical Systems, Inc. site throughout the areas of
attainment during the implementation (i.e., the reduction of
contaminant concentrations using the selected remedy levels off
above remedial goals) contingency measures will be protective of
113
-------
human health and the environment,- and are technically practicable
under the circumstances.
To determine if the contingency measures are necessary, the vapor
extraction systems for the alternative combinations will be closely
monitored by the analysis of soils and ground water samples. The
monitoring will take place throughout the implementation of the
remedy and the system's performance will be carefully evaluated.
Adjustments in the operation of the system may be made to try to
improve the systems' effectiveness. If it appears that the system
cannot attain the remedial goals set for the site, contingency
measures including one, some or all of the activities below will
be implemented:
a) discontinuing operation of in-situ air stripping and
using extraction wells and/or trenches to remove
contaminated ground water in areas where cleanup goals
have not been attained. The extracted ground water would
then be run through an air stripper and the extracted
contaminant-laden vapor would be run through the
catalytic oxidation unit;
b) establishing an Alternative Concentration Limit ("ACL")
for the contaminants throughout the areas of attainment,
provided compliance with CERCLA Section 121 (d) (2) (B)
(ii) can be demonstrated;
c) waiving the ground water ARAR for those portions of the
aquifer based on technical impracticability of achieving
further contaminant reduction;
d) containment of the contaminated soil and ground water by
caps and slurry walls;
e) implementing additional source control treatment to
further reduce contaminant migration to ground water.
The decision to invoke any or all of these measures may be made
during a periodic review of the remedial action. Depending on
whether a significant or fundamental change is proposed, an
Explanation of Significant Differences or an Amendment to the
Record of Decision will be issued to inform the public of the
details of the modification. A change from active restoration to
passive restoration would be considered a fundamental change.
The remedial design will specify the appropriate number and
location of injection and extraction wells and monitoring points,
and system parameters such as the air flow rates for both the soil
vapor extraction and the in-situ air stripping of ground water
contaminants into the catalytic oxidation unit. The contaminated
vapors destroyed by running the vapor through the catalytic
oxidation unit will periodically exhaust the ability of the
114
-------
catalyst to destroy the contaminants, at that time the catalyst
will need to be replaced and disposed of at a licensed
treatment/disposal facility. Some modifications or refinements may
be made to the remedy during remedial design and construction.
Such modifications or refinements, in general, would reflect
results of the engineering design process. The estimated total
present worth remedial cost for the site is $26,430,000. Table 9-
2 shows the present worth cost, capital cost, O&M cost,and project
management cost for the five identified waste disposal areas of the
site.
The contaminant remediation levels selected for the contaminated
soils and ground water are protective of human health and the
environment. They are, as previously discussed in section 6
(Summary of Site Risk):
SOIL CRITERIA
Benzene 10 parts per million (ppm) See * below
at depths less than 10 feet See * below
0.35 ppm at depths greater
than 10 feet *
Lead 500 ppm See ** below
Naphthalene 70 ppm Health Based
Value
GROUND WATER
Benzene 5.0 parts per billion (ppb) MCL
Ethylbenzene 700 ppb MCL
Xylene 10,000 ppb MCL
Naphthalene 327 ppb Health Based
Value
Lead 15 ppb Action Level
* The remedial goal for benzene in the soil was determined based
on the potential of the benzene contamination in the soil to
leach into the underlying ground water aquifer, resulting in
benzene contamination of the ground water exceeding the
benzene MCL for drinking water. The SESOIL model was used to
do this determination. It should also be noted that if
detectable concentrations of benzene are found at depths
greater than 10 feet, the entire soil column (from the ground
surface to the maximum depth of contamination) would be
remediated to a contaminant level of 0.35 ppm.
** The lead concentration goal was based on the Interim Guidance
on establishing Soil Lead Cleanup Levels at Superfund Sites,
September 7, 1989.
Based on findings in the Baseline Risk Assessment for the Current
and Future Residential scenarios, the remedial action objectives
115
-------
TABLE 9-2
SELECTED REMEDY. ESTIMATED COST
Page 1 of 3
ITEM DESCRIPTION
CAPITAL AMD OPERATING COSTS
1 TESTING
- Aquifer
- Vapor Extraction
- In Situ Stripping (Ground water)
- Geo/Civil Data
MAIN WASTE AREA
Amount
l
1
1
1
Unit
LS
LS
LS
LS
Unit
Cost
Cost
80,000
90,000
90,000
60,000
SUBTOTAL - TESTING 320,000
2 DESIGN (10% of construction) 309,000
3 CONSTRUCTION
Site Preparation
- Property Control
- Relocate utilitiee
- Nell Removal
- Temporary Fencing
- Surveying
- Clearing and Grubbing
Contouring
Runon/Runoff Control »
- B«rm» and Seeding
In-Situ Vapor Extraction
- Install Extraction Points
- Install Cap
- slurry Hall
- In situ air stripping points
- Catalyic oxidizer
Construct permanent fence
Contingency f25%)
25
1
0
4,000
20
37,778
37,778
2,300
75
340,000
69,000
17
1
4,000
ACRES
LS
NELL
LF
DAY
-SY
SY
LF
NELL
SF
SF
NELL
LS
LF
2,000
10,000
2,000
6
500
1
1
4
5,000
4
4
5,000
150,000
10
50,000
10,000
0
24,000
10,000
47,200
39,300
9,200
372,800
1,360,000
276,000
86,800
150,000
40,000
619.000
SUBTOTAL - CONSTRUCTIOM 3,094,000
4 OPERATION/MAINTBNANCE/MOHITORING
Labor
- Manpower (3 Ban crew 24 hr)
- Miscellaneous Labor
Energy Costs
- catalytic Oxidizer Energy Cost
30 Year Monitoring Cost
- Sampling
- Laboratory Analyses
- Fence Repair
- Moi/ing/revegetation
- cap repair
- Trench/Sump maintenance
contengency (25%)
60
60
30
30
30
30
30
30
MO
MO
YR
YR
YR
YR
YR
YR
75, COO
5,940
9,600
14,400
2,000
1,000
10,000
10,000
4,536,000
356,400
119,100
178,700
24,800
12,400
124,100
124,100
1,369.000
SUBTOTAL - OPERATION/MAIHTZNANCE/MOMITORING 6,845,000
5 PROJECT MANAGEMENT 3,000,000
TOTAL C0«* MVXM»n »J.i,f«e,MO
OFFICE TRAILER AREA
Amount
1
1
l
1
Unit
LS
LS
LS
LS
unit
Cost
Cost
20,000
30,000
30,000
25,000
105,000
248,000
25
1
0
4,000
20
30,800
30,800
2,700
55
277,200
81,000
12
4,000
ACRES
LS
NELL
LF
DAY
SY
SY
LF
NELL
SF
SF
NELL
LF
2,000 50,000
10,000 10,000
2,000
6
500
1
1
4
5,000
4
4
5,000
10
0
24,000
10,000
38,500
32,000
10,800
275,000
1,108,800
324,000
57,500
40,000
495.000
2,476,000
30
30
30
30
30
30
YR
YR
YR
YR
YR
YR
9,600
14,400
15,400
1,000
10,000
10,000
200,000
119,100
;^8,700
iS 1,000
12,400
124,100
124,100
187. OOP
1,137,000
500,000
116
POOR QUALITY
ORIGINAL
-------
TABLE 9-2
SELECTED REMEDY ESTIMATED COST
Page 2 of 3
ITEM DESCRIPTION
CAPITAL AND OPERATING COSTS
1 TESTING
- Aquifer
- Vapor Extraction
- In Situ Stripping (Ground water)
- Geo/Civil Data
WEST ROAD AREA
Amount
1
1
1
1
Unit
LS
LS
LS
LS
Unit
Cost
Cost
20,000
30,000
30,000
20,000
SUBTOTAL - TESTING 100,000
2 DESIGN (10% of construction) 147,000
3 CONSTRUCTION
Site Preparation .
- Property Control
- Relocate utilities
- well Removal
- Temporary Fencing
- Surveying
- Clearing and Grubbing
Contouring
Runon/Runoff Contrpl
- Beras and Seeding »
In-Situ Vapor Extraction
- Install Extraction Points
- Install Cap
- slurry Wall
- In situ air stripping points
- Catalyic Oxidizer
construct permanent fence
Contingency (25%)
25
1
0
2,000
20
10,078
10,078
1,200
10
90,700
36,000
6
1
2,000
ACRES
LS
WELL
LF
DAY
SY
SY
LF
WELL
SF
SF
WELL
LS
LF
2,000
10,000
2,000
6
500
1
1
4
5,000
4
4
5,000
100,000
10
50,000
10,000
0
12,000
10,000
12 , 600
10,500
'4,800
50,000
362,800
144,000
32,000
100,000
20,000
305.000
SUBTOTAL - CONSTRUCTION 1,023,000
4 OPERATION/NAINTENANCE/NONITORINC
Labor
- Miscellaneous Labor
Energy Costs
- Catalytic Oxidizer Energy Cost
30 Year Monitoring Cost
- Sampling
- Laboratory Analyses
- Fence Repair
- Mowing/revegetation
- Cap repair
- Trench/Sump maintenance
Contengency (25%)
60
30
30
30
30
30
30
MO
YR
YR
YR
YR
YR
YR
5,940
9,600
14,400
1,000
1,000
10,000
10,000
200,000
356,400
119,100
178,700
12,400
12,400
124,100
124,100
282.000
SUBTOTAL - OPERATION/MAINTENANCE/MONITORING 1,409,000
5 PROJECT MANAGEMENT 400,000
POWER EASEMENT AREA
Amount
1
1
l
1
Unit
LS
LS
LS
LS
Unit
Cost
Cost
40,000
30,000
30,000
40,000
140,000
200,000
15
1
0
3,000
20
21,167
21,167
1,350
66
181,500
74,250
0
1
3,000
ACRES
LS
WELL
LF
DAY
SY
SY
LF
WELL
SF
SF
WELL
LS
LF
2,000
10,000
2,000
6
500
1
1
4
5,000
4
4
5,000
100,000
10
30,000
10,000
0
18 , 000
10,000
25,200
21,000
5,400
330,000
726,000
297,000
0
100,000
30,000
401.000
2,004,000
60
30
30
30
30
30
MO
YR
YR
YR
YR
YR
5,940
6,400
9,600
1,500
1,000
10,000
500,000
356,400
79,400
119 , 100
18. COO
12,400
124,100
303.000
1, 513.OOO
500,000
TOTAL con tmrnaam », 0*0,000 4,3«*,M«
117
POOR Qu/\...
^ ORIGINAL
-------
TABLE 9-2
SELECTED REMEDY ESTIMATED COST
Page 3 of 3
ITEM DESCRIPTIOH
CAPITAL AND OPERATING COSTS
1 TESTING
- Aquifer
- Geo/Civil Data
BAYOU DISPOSAL AREA
Amount
1
1
Unit
LS
LS
Unit
Cost
70,000
50,000
Cost
70,000
50,000
SUBTOTAL - TESTING 120,000
2 DESIGN (10% of construction) 24,000
3 CONSTRUCTION
Sit* Preparation
- Property Control
- Relocate utilities
- well Removal
- Temporary Fencing
- Surveying
- Clearing and Grubbing
Runon/Runoff Control
- Bens and Seeding
Capping Cost
- Contouring
- RCRA Cap
- vegetative topsoil cover
Facilities
Construct permanent fence
Contingency (25%)
15
1
0
2,500
20
1,956
1,640
1,956
17,600
1,956
1
2,500
ACRES
LS
WELL
LF
DAY
SY
LF
SY
SF
SY
LS
LF
2,000
10,000
2,000
6
500
1.25
4
1.04
4
1.02
20,000
10
30,000
10,000
0
15,000
10,000
2,400
6,600
2,000
70,400
2,000
20,000
25,000
48.350
SUBTOTAL - CONSTRUCTION 241,730
4 OPERATION/MAIHTENANCE/MONITORING
Labor
- Miscellaneous Labor
30 Year Monitoring Cost
- Fence Repair
- Mowing/revegetation
- Cap repair
- sampling
- Laboratory Analyses
contengency (25%)
1
30
30
30
30
30
LS
YR
YR
YR
YR
YR
100,000
1,250
1,000
10,000
6,400
9,600
100,000
15,500
12,400
134,100
7*, 400
lit, 100
1H. 635
SUBTOTAL - OPERATION/MAINTENANCE/MONITORING 563,125
5 PROJECT KAKAGEKZMT 200,000
TOTAL con man i,i4«,7»«
COST BY AREA (IN THOUSANDS OF DOLLARS)
ITEM
1. Testing/Plan
Preparation
2 . Design
3 . Construction
4 . Operation/Maintenance/
Monitoring
5. Project Management
TOTAL
MAIN
WASTE
320
309
3,094
6,845
3,000
13,570
OFFICE
TRAILER
105
248
2,476
937
500
4,270
WEST
ROAD
100
147
1,023
1,409
400
3,080
EASEKEMT
140
147
2,004
1,513
500
4,360
BAYOU
DISPOSAL
120
24
242
562
200
1,150
TOTAl ESTIMATED ilTl OCMT $26,430,000
118
POOR QUALS'l Y
v ORIGINAL
-------
for this site are the following:
Objective l -
Criterion
Objective 2 -
Criteria
Objective 3 -
Criteria
Objective 4 -
Criteria
Objective 5 -
Criterion
Objective 6 -
Criterion -
Objective 7 -
Criterion
Objective 8 -
Reduce the risk of exposure to excavatec,
contaminated subsurface soils and waste to levels
that protect human health and the environment.
HUMAN HEALTH CRITERIA (10~6 health risk) for the
residential scenario.
Take necessary action where technically feasible to
prevent the subsurface soil/waste from acting as a
continuing source of pollutants, which would not
allow the contaminated ground water to be restored
to, and maintained at, levels consistent with future
drinking water use.
MCLG's, MCL's, proposed MCL's, HUMAN HEALTH CRITERIA
(10~6 health risk) for the residential scenario, or
WATER QUALITY CRITERIA.
Restore contaminated ground water for future
drinking water use where technically feasible in as
short a period as possible.
MCLG's, MCL's, proposed MCL's, HUMAN HEALTH CRITERIA
(10~6 health risk) for the residential scenario, or
WATER QUALITY CRITERIA.
Reduce the risk of human exposure to ground water
at the site contaminated above human health levels.
MCLG's, MCL's, proposed MCL'S, HUMAN HEALTH CRITERIA
(10~6 health risk) for the residential scenario, or
WATER QUALITY CRITERIA.
Reduce the risk of exposure from contaminated site
surface water generated by the remedial action to
levels that protect human health and environment.
HUMAN HEALTH CRITERIA (10~6 health risk) for the
residential scenario.
Reduce the risk of exposure from contaminated dust
or air emissions generated by the remedial action
to levels that protect human health and the
environment.
Permissible Exposure Limits.
Determine a permanent remedy for the material in the
temporary RCRA storage vault (the RCRA vault is part
of the Main Waste Area) that will protect human
health and the environment.
HUMAN HEALTH CRITERIA (10"6 health risk) for the
residential scenario.
Take necessary action where technically feasible to
prevent the RCRA vault soil/waste from acting as a
119
-------
continuing source of pollutants, which would not
allow the contaminated ground water to be restored
to, and maintained at, levels consistent with future
drinking water use.
Criteria - MCLG' s, MCL' s, proposed MCL' s, HUMAN HEALTH CRITERIA
(10"6 health risk) for the residential scenario, or
WATER QUALITY CRITERIA.
The goal of this remedial action is to restore the ground water to
its beneficial use, which is, at this site, use as a potential
source of drinking water. Based on information obtained during the
remedial investigation, the subsequent supplemental remedial
investigation, and the analysis of all remedial alternatives, EPA
and the State of Texas believe that the selected remedy will
achieve this goal. Ground water contamination may be especially
persistent in the immediate vicinity of the contaminants' source,
where concentrations are relatively high. The ability to achieve
remedial levels at all points throughout the area of attainment,
or plume, cannot be determined until the extraction system has been
implemented, modified as necessary, and plume response is monitored
over time. If the selected remedy cannot meet the remediation
goals for both soils and ground water, at any or all of the
monitoring points during the implementation, then contingency
measures and goals may replace the selected remedy and goals.
These measures would be protective of human health and the
environment, and would be technically practicable under the
circumstances.
X. STATUTORY DETERMINATIONS
EPA's primary responsibility at Superfund sites is to select
remedial actions that are protective of human health and the
environment. Section 121 of CERCLA also requires that the selected
remedial action for the site comply with applicable or relevant and
appropriate environmental standards established under
Federal and State environmental laws, unless a waiver is granted.
The selected remedy must also be cost-effective and utilize
permanent treatment technologies or resource recovery technologies
to the maximum extent practicable. The statute also contains a
preference for remedies that include treatment as a principal
element. The following sections discuss how the selected remedy
for contaminated source areas and contaminated ground water at the
Petro-Chemical Systems site meets the statutory requirements.
Protection of Human Health and th« Environment
In order to meet the remedial objectives outlined in the previous
section, the risks associated with exposure to the contaminated
source areas and contaminated ground water must fall within the
acceptable risks for the site contaminants. Attainment of remedial
levels outlined in section VI (Summary of Site Risk) will assure
120
-------
that site risks fall within this range (See Table 6-15) . These
risk levels are MCLs, contaminant specific action levels, and
calculated health-based values. The levels/values, when attained
by remediation, would insure that 1) soil contaminants would cease
to act as a source of ground water contamination, such that any
potential future leaching of the remediated soils would not result
in ground water contaminant concentrations above the MCLs, and 2)
exposure to the ground water will not pose adverse effects to the
potentially exposed future site population. The selected remedy
protects human health and the environment by reducing levels of
contaminants in the soils and ground water through extraction and
treatment, as well as through natural attenuation. EPA expects
that the contaminants in the site soils and ground water will be
reduced the remedial levels in five years. However, the ability
to achieve the remedial goals throughout the areas of contamination
cannot be fully determined until the extraction system has been
implemented, modified as necessary, and monitored over time.
Together with the containment components (cap and slurry wall) of
the remedy, the threat of exposure currently posed to residents
from contaminated soils and from contaminated ground water should
be significantly reduced if not eliminated. This RCRA cap will
specifically deal with the estimated 700 cubic yards of elevated
lead contamination (lead concentrations > 500 ppm) found in the
upper 6.5 feet in two areas of the Main Waste Area. Of all the
alternatives for the contaminated soils and contaminated ground
water, the selected alternatives provide the best overall
protection to human health without significant adverse impact to
the environment. No unacceptable short-term risks or cross-media
impacts would be caused by implementing this remedy.
Attainment of Applicable or Relevant and Appropriate
Requirements of Environmental Lavs
Source Control Remediation;
The selected soil remedy combining soil vapor extraction with
catalytic oxidation of extracted vapors and containment by cap and
slurry wall will comply with all applicable or relevant and
appropriate chemical-, action-, and location-, specific
requirements ("ARARs"). The ARARs are presented as follows:
Chemical Specific Soil Remediation ARARs;
RCRA Land Disposal Restrictions (LDRs) will not be applicable since
the selected remedy does not involved excavation and placement of
contaminated soils. Soil vapor extraction with catalytic oxidation
of extracted vapors is an in-situ process. There is the
possibility that the estimated 700 cubic yards of lead-contaminated
soils located in the Main Waste Area (concentrations > 500 ppm
lead) will be consolidated in the Main Waste Area prior to the
soils being capped in place with a RCRA cap. Since this con-
solidation of the lead contaminated soils would be taking place
121
-------
within a single "Area of Contamination" (AOC), (i.e, the Main Waste
Area), placement has not occurred and LDRs are not applicable to
this Superfund action.
NESHAP establishes regulations for specific air pollutants such as
benzene, which was determined to be one of the primary contaminants
at the site.
Action-Specific Soil Remediation ARARs;
The selected remedy will address and comply with action-specific
ARARs for treating the extracted vapors on-site and leaving low
level contaminant concentrations on the site. The ARARs that come
into play for the catalytic oxidation unit are as follows:
The Clean Air Ace, under the regulatory section on Permitting (40
CFR Part 61), requires permits for the discharge of pollutants for
point sources, area sources or fugitive emissions. The substantive
requirements for a permit will be required for discharge.
The TACB General Rules, specifically 31 TAG Section 101, require
compliance with EPA Federal Clean Air Act and NPAAQ Standards. The
substantive requirements for a permit will be required for all
operations. Section 101.4 of the TACB General Rules, 31 TAC 101.4,
prohibits the discharge of air contaminants which may tend to be
injurious to or adversely affect human health or welfare, animal
life, vegetation or property, or as to interfere with the normal
use and enjoyment of animal life, vegetation or property.
The requirements of TACB Standard Exemption No. 68 will be met.
This exemption states that, for soil and ground water stripping the
total emissions of air contaminants (except nitrogen, carbon
dioxide, air, oxygen, and water vapor) can not exceed five pounds
per hour. In addition, for soil stripping, operations must be
conducted at least 1,000 feet from any residence or other
structure, or any recreational area not occupied or used solely by
the operator of the property on which the operations are conducted.
Fugitive emissions monitoring, as specified in TACB Regulation V
or EPA's New Source Performance Standards (40 CFR 60) or EPA's
National Emission Standards for Hazardous Air Pollutants (40 CFR
61) will apply.
Since contaminants will be left on site (i.e., lead in the Main
Waste Area, low level threat material in the Bayou Disposal Area),
the RCRA Closure and Post Closure requirements must be met. CERCLA
establishes that remedial actions must be reviewed should
contaminants be left on site. Other substantive requirements will
be necessary, including monitoring and deed recordation.
The Solid Waste Disposal Act, Contingency Plan for Emergency
Procedures, Subpart D, will also be applicable since on-site
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treatment has been selected.
Location-Specific Soil Remediation ARARs;
Resource Conservation and Recovery Act (RCRA) requirements for
location of a Treatment, Storage or Disposal facility in a 100-
year floodplain, 40 CFR 264.18, and also general requirements for
the protection of floodplains, 40 CFR 6, Appendix A, are relevant
and appropriate because the site is within the 100-year flood
plain.
Ground Water Remediation;
The selected ground water remedy for the Main Waste Area, the
Office Trailer Area, the West Road Area, and the Easement Area
includes: removal of volatile organic contaminants from ground
water using vapor extraction (in-situ air stripping), collection
and transport of the extracted vapor to the catalytic oxidation
unit, and use of the containment alternatives (cap and slurry
wall) . The ground water remedy for the East part of the East
Disposal Area and the deep (1001) aquifer under the Office Trailer
Area, may include (depending on the results of sampling during the
remedial design); extraction, storage in tanks, testing and
subsequent treatment and/or discharge of contaminated ground water.
These remedial actions will comply with all applicable and
appropriate action-, chemical-, and location specific requirements
(ARARs). These regulations are as follows:
Action Specific Ground Water Remediation ARARs;
Resource Conservation and Recovery Act (RCRA) requirements for
Post-Closure and Monitoring, 40 CFR 264.117(a) (1), will be
requirements for at least 30 years.
The action-specific ARARs previously discussed (TACB Standard
Exemption No. 68, 31 TAC 101.4, and 40 CFR Part 61) in the source
control remedial ARAR section, which relate to the treatment of
extracted ground water vapors by the catalytic oxidation unit, are
also applicable with treatment of the ground water.
The National Pollutant Discharge Elimination System (NPDES), 40 CFR
Part 125, requires permits for the discharge of pollutants for any
point source and storm-water runoff for specific SIC codes into
waters of the United States. Substantive requirements for a permit
must be met for discharge to a surface water body at the Petro-
chemical Systems, Inc. site, if on-site ground water treatment
occurs and is discharged instead of reinjected.
The Safe Drinking Water Act, Underground Injection Control
Regulations (40 CFR Parts 144-147), provides for protection of
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underground sources of ground water. This will be an ARAR if
ground water remediation involves injection to enhance remediation.
Standards for Owners and Operators of Hazardous Waste Treatment,
Storage and Disposal (TSD) Facilities, Subpart I (Use and
Management of Containers) , and Subpart J (Tanks) are also ARARs.
These will be ARARs for ground water because the selected
alternative may involve storage of containers of hazardous waste
or involve the use of tanks to treat or store hazardous materials
if it is determined during the remedial design that the ground
water from the deep (1001) water-bearing zone beneath the Office
Trailer Area or the ground water from the East part of the East
Disposal Area require remedial action.
The State of Texas Rules, Wastewater Permitting, 26 T.W.C., 31
T.A.C. 305, allow TWO to issue permits for the discharge of waste
into or adjacent to waters of the state. This will be an ARAR if
the remedy requires discharge of treated wastewater or storm-
water.
Under 31 TAG 115.132, volatile organic compound water separators
must apply one of the following control measures:
Sealed vessel (vapor tight), or
Floating roof or internal floating cover, or
Vapor recovery systems which meets requirements of
31 TAG 115.131(a).
Exemptions are provided in 31 TAG 155.137.
This will be an ARAR if volatile organic compound water separators
are used.
Chemical-Specific Ground Water Remediation ARARs:
The National Primary Drinking Water Standards establish health-
based standards for public water systems (maximum contaminant
levels - MCLs). MCLs are ARARs at the site since the affected,
ground water may be potentially used as a future drinking water'
source.
Sections of the Clean Water Act and regulations concerning Water
Quality Criteria (WQC) and Ambient Water Quality Criteria (AWQC),
40 CFR Part 131, set criteria for water and ambient water quality
based on toxicity to human health and toxicity to aquatic
organisms, respectively. WQCs and AWQCs for site chemicals are
ARARs if the selected alternative calls for discharge to a surface
water. Because activities will be performed on-site, permits may
not be required, but the technical standards of the permits must
be met.
The Drinking Water Standards for Public Water Supply Systems
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establish health-based standards for a specific list -of
contaminants for public water supply systems. These are identical
to federal standards promulgated under the Safe Drinking Water Act
and are site ARARs.
Under the State of Texas Rules, Surface Water Quality Standards (31
T.A.C Sections 307.1-307.10), criteria are established for surface
water quality and criteria and control procedures for specific
toxic substances. These are ARARs if the selected alternative
calls for discharge to a surface water.
Location-Specific Ground Water Remediation ARARs:
Under the State of Texas Rules, Ground Water Protection Act, 26
T.W.C. .403-.406. Ground water is required to be restored, if
feasible. This is an ARAR because ground water is affected.
RCRA requirements for location of a Treatment, Storage or Disposal
facility in a 100-year floodplain, 40 CFR 6, Appendix A and 40 CFR
264.18, are applicable since the eastern section of the site is
within the 100-year flood plain of a Turtle Bayou tributary.
Cost Effectiveness
EPA believes that the selected remedy is cost-effective in
mitigating the principal threat waste and low level threat waste
at the site, and the site's primary risk, ingestion of contaminated
ground water. Section 300.430(f)(ii)(D) of the NCP requires EPA
to determine cost-effectiveness by evaluating the following three
of the five balancing criteria to determine overall effectiveness:
long-term effectiveness and permanence, reduction of toxicity,
mobility or volume through treatment, and short-term effectiveness.
Overall effectiveness is then compared to cost to ensure that the
remedy is cost effective. EPA believes the selected remedy meets
these criteria. The estimated cost for the selected remedy is
$26,430,000.
*
Utilization of Permanent Solutions and Alternative Treatment
Technologies or Resource Recovery Technologies to the Maximum
Extent Practical
EPA believes the selected remedy represents the maximum extent to
which permanent solutions and treatment technologies can be
utilized in a cost-effective manner for the Petro-Chemical Systems
site. Of those alternatives that are protective of human health
and the environment and comply with ARARs, EPA has determined that
the selected remedy provides the best balance in considering long-
term effectiveness and permanence; reduction in toxicity, mobility
or volume through treatment; short-term effectiveness;
implementability; and cost, as well as considering the statutory
preference for treatment as a principal element and considering
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State and community acceptance.
The air injection with vapor extraction and catalytic oxidation of
extracted vapors alternative, in combination with the containment
alternatives (cap and slurry wall) , complies with ARARs and reduces
the toxicity, mobility, and volume of the contaminants in the site
soils and ground water. The in-situ aspect of these alternatives
was critical in choosing these alternatives based on the estimated
volume of contaminated soils and ground water requiring remedial
action and the volatile nature of the site contaminants. Short-
term effectiveness and protection of human health and the
environment, as well as the site remedial cost, are satisfied
effectively by the selected remedy.
The State of Texas is in concurrence with the selected remedy. The
Proposed Plan for the Petro-Chemical Systems site was released for
public comment in June 1991. The Proposed Plan identified the air
injection with vapor extraction and catalytic oxidation alternative
and the containment alternative (RCRA cap for the Bayou Disposal
Area) as the preferred source control remedy. The Proposed Plan
also identified the extraction and treatment of ground water by
catalytic oxidation or carbon adsorption as the preferred ground
water alternative. EPA reviewed all written and verbal comments
submitted during the public comment period. Upon review of these
comments, EPA determined that a few significant changes to the
remedy originally identified in the Proposed Plan were necessary.
These are discussed in Section XI, Documentation of Significant
Changes.
Preference for Treatment as a Principal Element
The selected remedy satisfies the statutory preference for
treatment as a principal element. The primary risk to human health
is from ingestion of and direct contact with contaminated ground
water. The selected remedy reduces levels of site contaminants in
ground water through treatment using air injection with vapor
extraction (in-situ air stripping), as well as addressing the
source areas by treating the highest contaminated soils (the
principal threat waste) by air injection with soil vapor extraction
and catalytic oxidation of the extracted vapors. This will be
combined with the containment alternatives (cap and slurry wall)
to contain the low level threat waste.
XI. DOCUMENTATION OF SIGNIFICANT CHANGES
The Proposed Plan for the Petro-Chemical Systems, Inc. site was
released for public comment in June 1991. The Proposed Plan
identified soil alternative 9 (Vapor Extraction and Catalytic
Oxidation), to address soil contamination in the Main Waste Area,
Office Trailer Area, West Frontier Park Road Area, and the Easement
Area. Isolated areas with high lead concentrations were to be
excavated and placed in the Bayou Disposal Area. The lead
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contaminated soils and low level threat wastes in the Bayou
Disposal Area would then be capped. The preferred ground water
alternative included extraction of ground water by a combination
of trenches and wells and treatment by carbon adsorption or
catalytic oxidation. EPA reviewed all written and verbal comments
submitted during the public comment period. Upon review of these
comments, it was determined that a few significant changes to the
remedy, as it was originally identified in the Proposed Plan, were
necessary. These changes, based on comments received and further
evaluation of the remedial alternatives, are as follows:
For the source control alternatives:
The isolated areas of lead contaminated soil, originally proposed
to be moved to the Bayou Disposal Area, will remain in the Main
Waste Area and be capped there.
For the contaminated ground water alternatives:
The ability to remove the contaminants in the ground water by in-
situ air stripping will be evaluated during the pilot study planned
for the Remedial Design. If it is determined that in-situ air
stripping will not be able to adequately remove contaminants in the
ground water, extraction of ground water by trenches and/or
extraction wells, as outlined in the Proposed Plan, will be used.
The East part of East Disposal Area and the deep water-bearing zone
beneath the Office Trailer Area, where limited ground water
contamination concentration data indicates that ground water would
require extraction but no treatment prior to discharge, will be
resampled during the remedial design. At that time, a deter-
mination will be made if remedial action is necessary. If remedial
action is necessary, the ground water will be extracted and stored
on-site in tanks. The water would subsequently be tested and
treated if contaminant concentrations exceed discharge levels.
Otherwise, the water will be discharged.
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APPENDIX A
RESPONSIVENESS SUMMARY
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