-------
TAnL[~ 13
SUHHARY Of EXCESS LifEliKE CAIICER RISKS AIID IIAlARD IIIDICES fOR TilE ARROUIIEAD PLATlIIG SI1E
Orlll SIonse "rea Acid hnk Areo Solvent Tonk Area Drain Lines Area Shilled Areo
-----.-.--.---.-----.---. .-.------------.--.-...---- ---------------.-.------- ----..-----------------.. '"'.---....-........ ----..... -.... --...
Excess L I fel line Ilazard hcess L I 'et IDle Uiilud Excess Li let I Ole' IlIlZard Excess L lIet IUle Ullurd Excess L Ilet IUle UOfUrd
Exposure Pathway Clncer Illk I ""ell Cancer III sic ItxJu Cancer R Islc I/ldex COllcer Risk Index Cancer Risk I/ld.:x
Ingestion 0' Grolllll "liter (a) 8E-02 >1 8E-02 >1 8E-02 >1 OE-02 >1 8E-Ol >1
Inhalation 0' Airborne VOCs 1f-08 1 OE-02 >1 OE-02 >1 Of-02 >\ 8E-02 >1
-- ;; 110 chemlc:ols uhlbltlng this effect (carcinogenic or noncarcinogenic) were present in Ihls OIediuo IIlxJ source area, or Inadequale tOKlcitV data to evaluate carcino-
Qellic or noncuc:lnogenlc: ellect. 01 chewlcals present In thbi AlediuM 0111.1 60llrce IIl'ell.
a The excess lifetime cancer risks and hazard indices are based on the future residential use scenario.
w
......
-------
the limited extent of the contamination associated with soils at
the Site. Inorganic substances were detected in groundwater above
background levels, but these levels were not of concern for human
health.
contaminated groundwater is also discharging to Scates Branch,
a small creek which eventually discharges to Weaver's Millpond
about one mile downstream. None of the volatile contaminants were
detected in the pond. Concentrations of contaminants in surface
water and sediment do not present a significant risk to local
residents who might utilize these areas.
In addition to the human health risk assessment, an
environmental risk assessment was also conducted to determine the
significance of the impact the site has to the environment. In
this assessment, the eastern tiger salamander and aquatic organisms
as a group were identified as potential environmental receptors
near the site. The eastern tiger salamander was selected because
it is on the State Endangered Species list and had potential to be
found near the site. This salamander is not a Federal endangered
species. Exposure potential for most terrestrial animals is
minimal because the chemicals of concern at the Site show little
potential for bioaccumulation. The state endangered eastern tiger
salamander, an amphibian, is terrestrial as an adult, but it lays
eggs in surface water. The eggs hatch into aquatic larvae, where
direct contact with surface water and sediment occurs.
The results of the environmental assessment indicate that
groundwater discharging to surface water could adversely affect
aquatic life. Several inorganic substances were detected in
surface waters at concentrations that slightly exceed criteria to
protect aquatic life, including copper, cadmium, and cyanide.
Consequently, it is possible that aquatic life in the surface water
near the Site may be negatively impacted. Groundwater also
discharges some VOCs from the aquifer to the nearby surface water.
38
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Concentrations of VOCs in seep samples were high enough to have a
potential adverse effect on aquatic life. However, due to the
volatility of these substances, a high percentage will likely
evaporate to the air within a short distance downstream.
VII. DESCRIPTION OF ALTERNATIVES
During the FS, several technologies potentially applicable to
remediating the site problems were screened based on their
effectiveness, implementability and cost. The screening process
identifies those technologies that are most appropriate for
reducing the toxicity, mobility and volume of the groundwater
contamination at the Site. Since soil remediation would facilitate
the restoration of the contaminated portion of the aquifer,
remedial technologies applicable to the treatment of contaminated
soils were also screened. To achieve the cleanup levels, remedial
technologies are combined to form the following remedial
alternatives:
Alternative 1:
Alternative 2a:
Alternative 2b:
No. Action
Groundwater Extraction and Treatment by
Precipitation, Air Stripping, and Carbon
Adsorption. Soil - Treatment by In-situ
Vapor Extraction. Institutional
Controls.
Groundwater Extraction and Treatment by
Precipitation, Air Stripping, and Carbon
Adsorption. Soil Excavation and
Treatment by Offsite Incineration and
Offsite Disposal. Institutional
Controls.
39
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Alternative 3a:
Alternative 3b:
Alternative 4a:
Alternative 4b:
Groundwater Extraction and Treatment by
Precipitation, Ultraviolet Oxidation, and
Carbon Adsorption. Soil Treatment by In-
si tu Vapor Extraction. Insti tutional
Controls.
Groundwater Extraction and Treatment by
precipitation, Ultraviolet Oxidation,
Carbon Adsorption. Soil Excavation and
Treatment by Offsite Incineration and
Offsite Disposal. Institutional
Controls.
Groundwater Extraction and Treatment by
Precipitation, Steam stripping, and
Carbon Adsorption. Soil Treatment by In-
si tu Vapor Extraction. Insti tutional
Controls.
Groundwater Extraction and Treatment by
Precipitation, steam Stripping, and
Carbon Adsorption. Soil Excavation and
Treatment by Offsite Incineration and
Offsite Disposal. Institutional
Controls.
Common Elements. Except for Alternative 1, all alternatives
would include a groundwater extraction system designed to minimize
migration of the contaminated groundwater and to remove
contaminated groundwater from the aquifer for treatment. The
initial estimate for the groundwater extraction network consists of
approximately 8 to 10 extraction wells, resulting in a total
pumping rate of 30 gallons per minute. Pumping tests will be
necessary to determine the optimal design for a groundwater
extraction system. The extracted groundwater would be conveyed to
40
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. . a treatment system composed of units that meet the definition of
tanks as specified in Virginia Hazardous Waste Management
Regulations (VHWMR) ~ 10.9, and prevent the escape of volatilized
contaminants. The treated water would be discharged to Scates
Branch (Figure 5). Groundwater monitoring would be periodically
conducted. At a minimum, the influent of the treatment system will
be sampled monthly and selected wells will be sampled quarterly for
volatile organics, metals (target analyte list), and total cyanide.
In addition, monitoring to ensure protection of aquatic life in the
nearby surface water would also be conducted. The environmental
monitoring requirements are specified in more detail in the Section
IX of this ROD, which is entitled Selected Remedy and Performance
Standards. Periodic review of the overall effectiveness of the
remedy will be conducted at a minimum of every five (5) years after
the initiation of the remedial action. For the purpose of cost
estimate, it is assumed that the groundwater treatment period would
extend approximately 30 years, although this period may be longer
or shorter depending on how the aquifer responds to the pump-and-
treat system. As part of the soil remedy, all alternatives, except
the No Action Alternative, would define more precisely the extent
of VOCs contamination in the soils at the site.
The discharge of treated water to surface water is expected to
meet Virginia Pollution Discharge Elimination System (VPDES) (Code
of Virginia ~~ 62.1-44.2 et ~) requirements developed by the
Virginia State Water Control Board (VSWCB) pursuant to the Federal
Clean Water Act and Virginia State Water Control Law. Section IX
specifies in more detail the VPDES requirements for the groundwater
remedy at the site. Air emissions from the treatment system are
expected to meet requirements under the National Emission Standards
for Hazardous Air Pollutants (NESHAPs) developed under the Federal
Clean Air Act and the Virginia Regulations for the Control and
Abatement of Air Pollution (VRCAAP). Air monitoring will be
conducted to ensure that emissions are protective of onsite workers
41
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FIGURE 5
Groundwater Extraction, Treatment. and Discharge Process Schematic
Otl-gas treatment
t
INORGANIC ORGANIC Treated eflillentto
TREATMENT Discharge
PRETREATMENT ~ . be discharued In to
(e.g., pH adjustment. (Air Stripping! accordance wilh Scates Branch
lIocculatlon. flllrallon\ Carbon Adsorption) NPDES limlls
Extraction System
(Typical Extraction Well)
04- Ground Surface
.-,
10
~
N
NOT TO SCALE
Waler Table
LEGEND
Overburden
-- - -, Ground Sill lace
04- Overburden/Clay
Inlerlace
-.......,.-_. Walor Tablo
Clay
121 Ovorburden
GJ Clay
.f Groundwater Flow
-------
. . and the nearby community. Residual wastes generated by the
treatment process would be disposed in accordance with treatment,
storage, and disposal regulations under the Resource Conservation
and Recovery Act (RCRA) , including Land Disposal Restrictions
(LDRs), and VHWMR. Carbon filters used in the process will be
disposed offsite or regenerated according to LDRs under RCRA.
Transportation of the wastes from the Site is expected to be in
compliance with VHWMR, Part VII, and U.S. Department of
Transportation Rules for transportation of Hazardous Materials.
Treatability tests for both groundwater treatment
soil treatment system are necessary to determine design
for all alternatives, except Alternative 1.
system and
parameters
Alternative 1 - No Action
Under the NCP, the "No Action" alternative must be developed
to provide a base line for comparison of other alternatives. This
alternative would include semi-annual sampling of contaminated
groundwater, and groundwater sampling review every five (5) years.
The estimated cost for this alternative is 1.25 million dollars.
Alternative 2a Groundwater Extraction and Treatment
precipitation, Air strippinq, and Carbon Adsorption. soil
Treatment by In-situ Vapor Extraction. Institutional Controls.
by
Groundwater. This alternative utilizes a groundwater
extraction system and treatment of the contaminated water by
precipitation, air stripping, and carbon adsorption.
precipitation would remove inorganic contaminants to pretreat
the water prior to the air stripping step. The precipitation
process involves adjusting the pH to encourage precipitation
of inorganic compounds followed by flocculation/sedimentation
and filtration. After the precipitation step, the groundwater
would be conveyed to an air stripping unit, where the VOCs in
43
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the groundwater at the Site would be effectively removed. An
activated carbon adsorption step following the air stripping
treatment would remove residual contaminants as a polishing
step prior to discharge of the treated water to Scates Branch.
Air emissions would be periodically monitored to prevent
adverse impact on workers and the surrounding community, and
to ensure the effectiveness of the emission control unit. The
entire groundwater treatment train would be closed to prevent
any escape of VOCs into the air. Any offgas escaping from the
water during treatment would be captured and treated by carbon
adsorption prior to discharge to the atmosphere.
Soil. The contaminated soils would be treated by in-situ soil
vapor extraction technology. A soil vapor extraction (SVE)
system would force air through the contaminated soils. The
air passing through the soils would remove vaporized
contaminants from the soil particles . The entire soil
treatment train would be closed to prevent any escape of VOCs
into the air. Any offgas escaping from the soil during
treatment 'would be captured and treated by carbon adsorption
prior to discharge to the atmosphere.
Institutional Controls. In addition to groundwater and soil
remediation, Alternative 2a includes institutional controls,
which consist of State regulations and/or County ordinances
that prohibit use of water from the contaminated aquifer until
the aquifer has been remediated to acceptable levels.
capital Cost:
Annual Cost:
Present Worth:
Time to Construct:
$ 1,344,000
$11,833,000
$13,177,000
1 year
44
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Alternative 2b Groundwater Extraction and Treatment by
precipitation, Air stripping, and Carbon Adsorption. soil
Excavation and Treatment by Offsite Incineration and Disposal.
Institutional Controls.
Groundwater. Alternative 2b utilizes the same groundwater
treatment components as Alternative 2a.
Soil. The contaminated soils would be excavated and
transported offsite for incineration followed by offsite
disposal in an approved RCRA landfill, instead of using in-
situ vapor extraction as in Alternative 2a. It is assumed
that approximately 750-1,000 cubic yards of contaminated soil
would be excavated and transported to a permitted offsite
incineration facility prior to disposal. The exact volume of
soil requiring excavation will be determined in the remedial
design. The excavated area(s) would be backfilled with clean
soil and revegetated.
Institutional Controls. Alternative 2b includes institutional
controls as described in Alternative 2a.
capital Cost:
Annual Cost:
Present Worth:
Time to Construct:
$ 5,815,000
$11,758,000
$17,573,000
1 year
Alternative 3a Groundwater Extraction and Treatment by
precipitation, Ultraviolet Oxidation, and Carbon Adsorption. soil
Treatment by In-situ Vapor Extraction. Institutional Controls.
Groundwater. Under this alternative, ultraviolet (UV)
oxidation would be the major groundwater treatment process.
The precipitation and carbon adsorption components are
identical to Alternative 2a. The UVjoxidation process is an
45
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emerging groundwater treatment technology that uses a
combination of ultraviolet light and a strong oxidizing
agent(s) to convert the organics in the groundwater to carbon
dioxide, chloride and water. Most commonly used oxidants
include hydrogen peroxide (HzOz) and ozone (03).
Soil. To treat the contaminated soils, this alternative
employs the soil vapor extraction technology as described in
Alternative 2a.
Institutional Controls . Institutional controls for this
alternative would be as described in Alternative 2a.
Capital Cost:
Annual Cost:
Present Worth:
Time to Construct:
$ 1,578,000
$11,341,000
$12,919,000
1 year
Al~erna~ive 3b Groundwa~er Ex~rac~ion and Trea~men~ by
Precipi~a~ion, Ul~raviolet oxida~ion, and Carbon Adsorp~ion. Soil
Excav~~ion and Treatmen~ by Offsite InciDera~ion aDd Disposal.
Ins~i~u~ional Con~rols
Groundwater. Alternative 3b uses the
treatment components as Alternative 3a.
same
groundwater
Soil. The contaminated
transported offsi te for
disposal in an approved
Alternative 2b.
soils would be excavated and
incineration followed by offsite
RCRA landfill, as described in
Institutional Controls. Alternative 3b includes institutional
controls as described in Alternative 2a.
46
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capital Cost:
Annual Cost:
Present Worth:
Time to Construct:
$ 6,049,000
$11,279,000
$17,328,000
1 year
Alternative 4a Groundwater Extraction and Treatment by
Precipitation, steam stripping, and Carbon Adsorption. Soil
Excavation and Treatment by attsi te Incineration and Disposal.
Institutional Controls
Groundwater. Alternative 4a utilizes a high-efficiency steam
stripper (HESS) unit as the major groundwater treatment
component to remove the vacs contaminants from the
groundwater. A precipitation unit would pretreat the
groundwater to remove inorganics as described in Alternative
2a. HESS uses steam. to evaporate volatile organics from the
groundwater. The. decontaminated water coming out of the
stream stripping tower is expected to meet the VPDES
. requirements. The vapor effluent of the stripping tower would
subsequently pass .through a condensing heat exchanger in which
.organics are recovered. An activated carbon bed would trap
residual organics in the vapor effluent prior to discharge to
the atmosphere. Air emissions would be periodically monitored
to prevent adverse impact on workers and the surrounding
community, and to ensure the effectiveness of the emission
control unit.
Soil. This al ternati ve
to treat contaminated
Alternative 2a.
would employ in-situ vapor extraction
soils at the Site as described in
Institutional Controls. Alternative 4a includes institutional
controls as described in Alternative 2a.
47
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Capital Cost:
Annual Cost:
Present Worth:
Time to Construct:
$ 2,398,000
$12,617,000
$15,015,000
1 year
Alternative 4b Groundwater Extraction and Treatment by
precipitation, steam stripping, and Carbon Adsorption. soil
Excavation and Treatment by affsi te Incineration and Disposal.
Institutional Controls
Groundwater. Alternative 4b utilizes the same groundwater
treatment scheme as in Alternative 4a.
Soil. The contaminated soils would be excavated and
transported offsite for incineration followed by offsite
disposal in a RCRA landfill, as described in Alternative 2b.
Institutional Controls. This alternative includes
institutional controls as described in Alternative 2a.
capital Cost:
Annual Cost:
Present Worth:
Time to Construct:
$ 6,869,000
$12,546,000
$19,415,000
1 year
VIII. SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES
This section compares the alternatives listed above in
accordance with the nine criteria required by the NCP, 40 CFR Part
300.430 (e) (9) for the evaluation of remedial alternatives (Appendix
A) . The nine criteria can be categorized into three groups:
threshold criteria, primary balancing criteria, and modifying
criteria.
48
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Threshold criteria:
1.
Overall protection
environment; and
the
human
of
health
and
2.
compliance with applicable
appropriate requirements.
or
relevant
and
Primary balancing criteria:
3.
Long-term effectiveness and permanence;
Reduction of toxicity, mobility, or volume
treatment;
Short-term effectiveness;
Implementability; and
Cost.
through
4.
5.
6.
7.
Modifying criteria:
8.
9.
State/Support agency acceptance; and
Community Acceptance.
Overall Protection of Human Health and the Environment
Because contaminant levels in the groundwater at the site have
exceeded health-based levels and contamination is likely to migrate
further from the Site, Alternative 1 (No Action Alternative) would
not be protective of human health. This alternative, therefore,
cannot be selected and will not be evaluated further.
All alternatives, except Alternative 1, are expected to be
protective of human health and the environment. The removal of
groundwater contaminants is expected to significantly reduce risk
associated with groundwater ingestion by future residents. Soil
remediation by these alternatives is expected to reduce the
49
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.migration of contaminants from soils into groundwater, thereby
protecting the environment and reducing risk involving soil
ingestion and dermal contact by future residents.
compliance wi tb Applicable or Relevant and Appropriate Requirements
(ARARs) and To-Be-Considered Materials (TBCS)
The NCP specifies that the remedial alternative selected must
comply with Federal and State ARARs. All alternatives, except
Alternative 1, are expected to comply with these requirements. In
addition, all alternatives are potentially capable of achieving the
cleanup levels for the groundwater at the Site. compliance with
the cleanup levels will be evaluated and monitored during the
remediation period, and additional response actions will be
implemented as necessary.
Lonq-term Effectiveness and Permanence
All alternatives, except Alternative 1, are expected to
permanently remove the contaminants from the groundwater and remove
volatile organics from the soils, thereby preventing the soils from
acting as a continuing source of contamination to groundwater at
the site. Therefore, the risks to human health and the environment
associated with groundwater contamination, which is the principle
risk posed by the Site, would be significantly reduced.
All remedial technologies employed in these alternatives have
been successfully used to treat similar contaminants at other
hazardous waste sites. The UV/oxidation process, however, would
require more testing to assure reliability. Both the UV/oxidation
process and HESS require more process monitoring than the air
stripping process to maintain reliability. Because all organic
contaminants in the Site groundwater are volatile compounds, air
stripping would be the most appropriate treatment process for the
groundwater. Alternatives 2a and 2b, therefore, provide a higher
50
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. . degree of reliability over other alternatives
treatment of contaminated groundwater at the Site.
with regard to'
Reduction of Toxicity, Mobility, or Volume through Treatment
All alternatives, except Alternative 1, are expected to
produce similar and significant reduction of toxicity, mobility and
volume of contamination associated with the groundwater and the
soils at the Site. These alternatives use different methods of
ultimate disposition of contaminants removed from the Site. In
Alternatives 2a and 2b (involving air stripping), organics from the
groundwater are collected by carbon, which would be sent offsite
for destruction or regeneration. A small amount of organics not
adsorbed by the carbon will be released into the air and to Scates
Branch with the effluent water. Alternatives 3a and 3b destroy
contaminants in groundwater by UVjoxidation treatment. In
Alternatives that utilize HESS (4a and 4b), contaminants in
groundwater are collected by an organic-water separator and sent
offsite for destruction or reclamation.
In Alternatives involving the use of SVE (2a, 3a, and 4a),
contaminants in soils are collected and treated prior to discharge
to the atmosphere. The used carbon would be sent offsite for
destruction or regeneration. In Alternatives 2b, 3b, and 4b, the
contaminated soils are sent offsite for treatment and disposal.
Short-term Effectiveness
Risks to workers,
implementation period
control measures.
the community and the environment during the
are expected to be minimized by emission
All alternatives, except Alternative 1, would discharge
treated water of acceptable quality to Scates Branch. In
Alternatives 2a, 2b, 4a, and 4b, air emissions would be cont~olled
51
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.by vapor phase carbon adsorption so that all adverse impacts to
workers and the surrounding community would be eliminated.
Monitoring of the performance of the emission adsorption unit will
be required to assure its effectiveness and the protection of human
health. In Alternatives 3a and 3b, no air emissions are expected
if only hydrogen peroxide is used in the treatment process for
groundwater.
In Alternatives 2a, 3a, and 4a, which utilize SVE, discharge
of volatile organics to the atmosphere would be monitored closely
for compliance with air emission regulations and to assure
protection of human health. Gas collected from the SVE process
would be treated by carbon adsorption to eliminate potential
impacts to workers and the nearby community. Alternatives 2b, 3b,
and 4b could result in a small release of volatile organics into
the air during the excavation period, which could last a few weeks.
It is unlikely that these emissions would produce an adverse impact
on the workers or the community due to their short duration, low
emission levels, and rapid dispersion. Excavation would be
conducted during cooler temperatures, and air in the vicinity of
the excavation area would be monitored to ensure compliance with
applicable air emission regulations and the protection of human
health. If unacceptable emissions occur, excavation activity would
be stopped. Transportation of wastes and excavation of
contaminated soils for offsite treatment and disposal would be in
compliance with applicable laws and regulations, and a health and
safety plan would be implemented to ensure protection of workers.
Implementability
All alternatives are technically implementable. Design and
construction for all alternatives is anticipated to take eight
months to one year. Air stripping,. carbon adsorption, UVI
oxidation, steam stripping, SVE, and offsite incineration have been
successfully demonstrated at other sites under similar conditions.
52'
-------
. However, UV/oxidation and HESS are emerging groundwater treatment
technologies, and service for these technologies is available
through only a limited number of vendors. Service for the air
stripping technology, on the other hand, is widely available.
operational and process monitoring requirements for Alternatives 2a
and 2b, which involve air stripping, are expected to be less
intensive than for the other alternatives since the air stripping
technology is simpler. Both SVE and offsite incineration/disposal
are relatively available in the market. In summary, Alternatives
2a and 2b are the most implementable ones among the alternatives
analyzed for the Site.
Cos1:
Treatment alternatives involving the use of either air
stripping (Alternatives 2a and 2b) or UV/Oxidation (Alternatives 3a
and 3b) cost relatively the same. Alternatives 4a and 4b, which
utilize steam stripping, cost approximately two million dollars
more.
The estimated total present worth for alternatives that
utilize SVE (2a, 3a, and 4a) ranges from 12.9 million dollars to 15
million dollars. For alternatives involving offsite incineration
and offsite disposal of soils, the estimated total present worth
ranges from 17.6 million to 19.4 million. Alternatives with
offsite incineration and offsite disposal (2b, 3b, and 4b) cost
approximately 4.4 million dollars more than the corresponding
alternatives (Alternatives 2a, 3a, and 4a), which employ the
respective groundwater treatment scheme and SVE to treat soils.
S1:a1:e/Suppor1: Aqency Accep1:ance
Both the Commonwealth of Virginia andEPA support the selected
remedy as described in Section IX of this ROD, selected remedy and
performance standards.
53
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community Acceptance
Community acceptance of the selected alternative is described
in the responsiveness summary of the ROD (Part III).
I~. SELECTED REMEDY AND PERFORMANCE STANDARDS
Based on the evaluation of alternatives using the nine
criteria and the public comments, both VDWM and EPA identify
Alternative 2a as the selected remedy for cleaning up the Site and
protecting human health and the environment. This alternative is
believed to provide the best balance of tradeoffs with respect to
the evaluation criteria. Among the balancing criteria,
implementability and long-term effectiveness and permanence
indicate that Alternative 2a is the most appropriate remedy for the
Site.
Under the selected alternative, the contaminated groundwater
will be extracted from the aquifer for treatment using a
combination of air stripping and carbon adsorption, and the
contaminated soils will be treated by soil vapor extraction. A
monitoring scheme would be conducted to ensure the effectiveness of
the remedy. Institutional control measures will also be developed
and implemented. Treatability tests for the groundwater treatment
system and soil treatment system are necessary to determine design
parameters for the selected remedy. Some changes may be" made to
the selected remedy as a result of the remedial design and
construction processes.
Work to be performed under this ROD shall be done in
accordance with final remedial design documents and remedial action
plans. In addition, the work shall comply with all ARARs and TBCs
as set forth in the Statutory Determinations Section of this ROD,
including but not limited to the specific standards discussed below
in this section, which must be met with respect to the elimination
54
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.of site contamination.
Major components of the selected remedy and the corresponding
performance standards for each component are detailed below.
Description of Groundwater Treatment Process
A groundwater extraction system would be installed to minimize
migration of the contaminated groundwater and to remove groundwater
from the aquifer for treatment. The initial estimate for the
groundwater extraction network consists of approximately 8 to 10
extraction wells, resulting in a total pumping rate of 30 gallons
per minute. Pumping tests will be necessary to determine the
optimal design for a groundwater extraction system. Following
extraction from the aquifer, the contaminated groundwater will be
conveyed to a treatment system composing of precipitation, air
stripping, and carbon adsorption units. The precipitation step
would remove inorganic contaminants to pretreat the water prior to
the air stripping step. The precipitation process. involves
adjusting the pH to encourage precipitation of inorganic compounds
followed by flocculation/sedimentation and filtration. After the
pretreatment step, the groundwater would be conveyed to an air
stripping unit, which would effectively remove the VOCs. An
activated carbon adsorption step following the air stripping
treatment would remove residual contaminants as a polishing step
prior to discharge of the treated water to Scates Branch. The
entire groundwater treatment train would be closed to prevent any
escape of VOCs into the air. Residuals generated by the treatment
process will be disposed offsite, and carbon filters will be
disposed or regenerated offsite. Any offgas escaping from the
water during treatment would be captured and treated by carbon
adsorption prior to discharge to the atmosphere. Air emissions
would be periodically monitored to prevent adverse impact on
workers and the surrounding community, and to ensure the
effectiveness of the emission control unit. Figure 5 depicts the
55
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groundwater treatment scheme under the selected remedy.
Groundwater Treatment Performance Standards
1. Effluent Discharae Limits. Following the extraction and
treatm~nt of groundwater, the treated water must be discharged to
the receiving stream (Scates Branch) in accordance with the
effluent discharge limits established by the VSWCB as set forth
below. These effluent discharge limitations require a toxics
monitoring program to be conducted as part of the discharge permit
requirements. These permit conditions may be modified as necessary
i£ new information generated in the remedial design/remedial action
(RD/RA) indicates significant changes in Site conditions.
Effluent Limitations
Parameter
Effluent Limitation (ua/l)
l,l,l-Trichloroethane
Tetrachloroethene
Trichloroethene
l,l-Dichloroethene
1,2-Dichloroethene (Total)
l,l-Dichloroethane
Acetone
2-Butanone
Methylene Chloride
Carbon Disulfide
Chloroform
Chloroethane
1,2-Dichloroethane
1,1,2-Trichloroethane
Benzene
Ethylbenzene
Vinyl Chloride
758928.6
40
360
NL
NL
NL
NL
NL
NL
NL
2098
NL
441.9
NL
236.6
1428.6
2343.8
56
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4-Methyl 2-pentanone
Toluene
Xylene (Total)
Total Cadmium
Total Copper
Total Nickel
Total Zinc
NL
781
169.6
32.6
25.7
344.7
231. 5
NL = No Limit; however, monitoring and reporting are required.
These limits shall be modified to comply with any applicable
effluent standard or limitation issued or approved under ~~
301(b) (2) (C), (D), and (E), 304(b) (2) (3) (4), and 307(a) (2) of
the Clean Water Act, if the effluent standard or limitation so
issued or approved:
(a)
contains different conditions or is otherwise more
stringent than any effluent limitation specified above;
or
(b)
Controls any pollutant of concern not limited by the
effluent limitations listed above.
Toxics Management Program
A. Biological monitoring:
( 1)
In accordance with the schedule in D. below and
commencing within six months following the initial
discharge of treated groundwater, the permi ttee
shall conduct quarterly acute and chronic toxicity
tests for a period of one year using 24-hour
composite samples of final effluent from the
discharge point. The acute tests shall be 48-hour
static test using CeriodaDhnia and PimeDhales
57
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(2)
Dromelas, both conducted in such a manner and at
sufficient dilutions "for calculation of a valid
LC50. The chronic tests shall be static renewal
tests using CeriodaDhnia and PimeDhales Dromelas.
The CeriodaDhnia test shall be a 7-day reproduction
test and the PimeDhales test shall be a 7-day
larval growth test. These chronic tests shall be
conducted in such a manner and at sufficient
dilutions to determine the "no Observed Effect
Concentration" (NOEC) for survival and growth or
reproduction. The permittee may provide additional
samples to address data variability during the one
year period of initial data generation. These data
may be included in the evaluation of effluent
toxicity. The results of all such additional
analyses shall be reported. Technical assistance
in developing the procedures for these tests shall
be provided by VSWCB, if requested by the
permittee. Test protocols and the use of
alternative species shall be approved by the state
water Control Board staff prior to initiation of
testing.
If the LC50 is greater than or equal to 100%
effluent in 6 or more of the total of 8 acute
toxicity tests, or in at least 75% of the tests
conducted if more than 8 tests are conducted, and
if the NOEC is greater than or equal to the in-
stream waste concentration (IWC) of 22.4% effluent
in 6 or more of the total of 8 chronic toxicity
tests, or in at least 75% of the tests conducted if
more than 8 tests are conducted, the permi ttee
shall continue acute and chronic toxicity testing
of the effluent from the discharge point annually.
The first annual tests shall be conducted within
58
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three months of the last quarterly tests~ The test.
organisms shall be those identified as the most
sensitive species from the quarterly acute and
chronic tests or alternative species approved by
the VSWCB staff.
(3)
If the LC50 is less than 100% effluent in 3 or more
out of the total of 8 acute toxicity tests, or in
more than 25% of the tests conducted if more than 8
tests are conducted, or if the NOEC is less than
the IWC of 22.4% effluent in 3 or more out of the
total of 8 chronic toxicity tests, or in more than
25% of the tests conducted if more than 8 tests are
conducted, a toxicity reduction evaluation will be
required.
(4)
If, in the testing according to (2) above, any of
the annual acute toxicity tests yields an LC50 of
less than 100% effluent or any annual chronic
toxicity test yields an NOEC of less than the IWC
of 22.4% effluent, the test shall be repeated
within 3 months. If the retest also indicates and
LC50 of less than 100% effluent or an NOEC of less
than the IWC, quarterly toxicity testing as in (1)
above shall commence within- three months. The
resul ts of these tests will be included in the
evaluation of the need for toxicity reduction. If
the retest does not confirm the results of the
first test, then annual testing in accordance with
the original annual compliance schedule shall
resume.
B. Chemical monitoring:
(1)
In accordance with the schedule in D, below and
59
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(2)
. .
commencing within six months following the initial
discharge of treated. groundwater, and continuing
quarterly for a period of one year, the permittee
shall collect 24-hour composite samples of the
effluent from the discharge point. These samples
shall be analyzed in the following manner:
(a)
Priority pollutant and non-priority pollutant
extractable organics using EPA's gas
chromatography-mass spectrometry method 625,
or other equivalent EPA approved methods. The
permittee shall:
( i)
report all priority pollutant organics
present at the method detection limits
established in method 625, and
(ii) tentatively identify and report a maximum
of 20 substances which are detected but
are not listed as priority pollutants
including all of the non-priority
substances of greatest apparent
concentration for the combined
base/neutral and acid extractable
fractions to a maximum of 20.
(b)
Organochlorine pesticides and PCBs using the
EPA method 608. The permittee shall determine
and report the concentrations of all compounds
listed in this method at the detection limits
specified in method 608.
The above chemical analyses shall be conducted
using EPA approved methods. The permittee shall
obtain approval from VSWCB staff before using non-
60
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(3)
EPA approved tests methods and/or detection and
reporting limits other than those required in this
special condition.
The above chemical analyses shall be conducted in
conjunction with the biological monitoring required
in A. (1) whenever possible. When the results of
biological testing indicate the necessity of
resuming quarterly toxicity testing, the quarterly
chemical analyses described in B. (1) shall also
resume. The permittee may provide additional
samples to address data variability during the one
year period of initial data generation. These data
may be included in the evaluation of effluent
toxici ty. The results of all such addi tional
analyses shall be reported.
c.
Toxicity Reduction Evaluation:
If the. results of this. Toxics Management program or other
available information indicate that the wastewaters are
actually or potentially toxic, the permittee shall submit: (1)
a toxicity reduction evaluation plan, or (2) at the
permittee's option, an in-stream impact study plan, and (3) an
accompanying implementation schedule within 120 days of the
notification of such a determination by VSWCB. The
requirement of this plan, pursuant to the Virginia Toxics
Management Regulation (VR 680-14-03), shall be to (1) assure
the absence of actual or potential toxici ty , or to (2)
demonstrate that there is, or would be, no adverse impact from
the discharge on all reasonable and beneficial uses of the
state's waters. Upon completion of the review of the plan,
the permit may be modified or alternatively revoked and
reissued in order to reflect appropriate permit conditions and
a compliance schedule.
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D.
Testing and Reporting Schedule:
The permittee shall conduct and report the results of the
toxicity tests and chemical analyses specified in this Toxics
Management Program in accordance with the following schedule:
( 1)
(2)
(3)
(4)
(5)
(6)
(7)
Submit toxicity
protocols for
approval
test
Conduct first
quarterly biological
and chemical tests
Submit results of
D. (2)
Conduct second
quarterly biological
and chemical tests
Submit results of
D. (4)
Conduct third
quarterly biological
and chemical tests
Submit results
D. (6)
Within two months following the
initial discharge of treated
groundwater
Within six months following the
initial discharge of treated
groundwater
With the Discharge Monitoring
Report (DMR) for the seventh
month following the initial
discharge of treated groundwater
Within nine months following the
initial discharge of treated
groundwater
With the DMR submitted for the
tenth month following the
initial discharge of treated
groundwater.
Within twelve months following
the initial discharge of treated
groundwater
with the DMR submitted for the
thirteenth month following the
initial discharge of treated
62
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groundwater
(8)
Conduct fourth
quarterly biological
and chemical tests
Within fifteen months following
the initial discharge of treated
groundwater
(9)
Submit results
with the DMR submitted for the
sixteenth month following the
permit effective date
D. (8)
(10) Conduct first annual
biological tests
Within eighteen months following
the initial discharge of treated
groundwater
biological tests
with the DMR submitted for the
nineteenth month following the
initial discharge of treated
groundwater
(11) Submit results
first annual
(12) Conduct subsequent
annual biological
tests
Within subsequent 12 month
periods from D. (10)
(13) Submit results of
subsequent annual
biological tests
with the DMR submitted every 12
months from D. (11)
2. CleanuD Levels. Groundwater extraction will continue
until the cleanup levels set forth in the following table are
achieved or until a determination is made that the cleanup levels
should be re-evaluated. Adjustment to these cleanup levels may be
necessary if stream monitoring in Scates Branch indicates that
fresh water criteria for the protection of aquatic life are being
violated. The fresh water criteria for this evaluation are those
values established by VSWCB as the effluent discharge limits for
63
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the groundwater treatment system as set forth in Item #1 above.
A. ORGANICS (~g/l)
Compound
Cleanup
8 *
Level'
1, 1, I-Trichloroethane
Tetrachloroethene
Trichloroethene
l,l-Dichloroethene
L,2-Dichloroethene (total)
Methylene chloride
1,2-Dichloroethane
1, 1, 2-Trichloroethane
Benzene
vinyl chloride
200
S
S
7
b70
Cs
s
Cs
S
d2
B. INORGANICS (~q/l)
Cleanup Fresh Water Drinking Water
* criteria-
Compound Level Standards
Cadmium 9TBD 0.66 810
Copper 9TBD S.7 cl, 300
Nickel 9TBD SO cIOO
Zinc 9TBD 47 fS, 000
8FederaJ maximum contaminant level (MCL) from 40 CFR, Part 141.
bMCL for cis-1,2-dichloroethene.
cProposed Maximum Contaminant Level (PMCL).
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dThis MCL goal is below the SW 8468240 detection limit. Therefore, either EPA.
method 524.1, 524.2, or 601 will be used to verify the concentration of vinyl
chloride in the groundwater. These methods have a 1 ppb detection limit for vinyl
chloride.
eVirginia Water Quality Criteria for Protection of Aquatic Life (VR 680-21-03.2).
f Secondary Maximum Contaminant Level (SMCL).
gTBD (to be determined) - Because the drinking water standards for these
contaminants are significantly higher than the corresponding fresh water criteria
for the protection of aquatic life, cleanup levels for these contaminants will be
developed during the remedial design. The established cleanup levels will not
exceed the drinking water criteria as promulgated under the Safe Drinking Water
Act. In addition, the cleanup levels will be established to ensure that the natural
discharge of groundwater from the Site to Scates Branch and its tributaries will not
result in a violation of the fresh water criteria for the protection of aquatic life.
*Monitoring of Scates Branch at points adjacent to the Site will be conducted to
verify that fresh water criteria for the protection of aquatic life are maintained.
These criteria are identical to the effluent discharge limits established by the State
Water Control Board for the groundwater treatment system at the Site, which are
in-stream criteria based on zero-flow conditions for Scates Branch. If stream
monitoring indicates that these criteria are being violated, the need for adjustment
to the groundwater cleanup levels will be evaluated.
3. Sludqe';Residue Manaqement. If sludge and/or residue
generated as a result of the treatment of groundwater is stored on-
site prior to off-site disposal, the storage must be in compliance
with Virginia Hazardous Waste Management Regulations (VHWMR) 9
10.8, Use and Management of Containers, or ~ 10.9, Tanks.
Transportation off-site of the sludge and/or residue must be in
compliance with VHWMR Part VII, Reaulations ADplicable to
TransDorters of Hazardous Waste, and 49 CFR Parts 107, 171.1-
172.558 regarding off-site transportation of hazardous wastes.
Description of Soil Treatment Process
The extent of contamination in soils and the action levels for
related contaminants would be determined during the remedial
65
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/
design. The contaminated soils would be treated by in-situ soil
vapor extraction technology. A SVE system would force air through
the contaminated soils. The air passing through the soils would
remove vaporized contaminants from the soil particles. The entire
soil treatment train would be closed to prevent any escape of VOCs
into the air. Any offgas escaping from the soil during treatment
would be captured and treated by carbon adsorption prior to
discharge to the atmosphere.
80i1 Trea~men~ Performance 8~andards
1. Soil CleanuD Levels. The soil vapor extraction will
continue until contamination from the soil is no longer a source of
release of contamination to underlying groundwater which results in
groundwater contamination above the established groundwater cleanup
levels. The cleanup criteria for the soil will be determined
during the remedial design by considering the characteristics of
the soils and associated contaminants and then deriving specific
levels of contaminants in soils that would not be expected to exert
a significant impact on the underlying groundwater.
Description of Environmen~a1 Moni~orinq
An environmental monitoring plan will be developed and
implemented to ensure the effectiveness of the remedy and to be
protective of human health and the environment. Periodic review of
the overall effectiveness of the remedy will be conducted at a
minimum of every five (5) years after the initiation of the
remedial action. The pump-and-treat system may be discontinued at
some point after the achievement of the groundwater cleanup levels.
However, if subsequent periodic reviews indicate that the
groundwater is not fully remediated, re-starting of the pump-and-
treat system may be necessary.
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Monitoring Performance standards
1. Air Monitorinq. Off-gas from the groundwater treatment
and soil vapor extraction units will be treated by carbon
adsorption units so that air emissions comply with the Virginia
Regulations for the Control and Abatement of Air Pollution (VRCAAP)
(VR 120-01-01) and are not a potential threat to the surrounding
community. Air emissions from the groundwater treatment unit and
the soil vapor extraction unit will be monitored in accordance with
protocol set forth below that has been established by the Virginia
Department of Air Pollution Control to ensure that emissions do not
in violate VRCAAP (VR 120-01-01) and are protective of human health
and the environment. In the event that monitoring indicates that
unacceptable emissions occur, appropriate control measures will be
developed and implemented to prevent any potential threat to human
health or the environment. In addition, the monitoring
requirements may be modified as necessary if new information
generated during the RDiRA indicates significant changes. in Site
conditions.
The following monitoring procedures should be adequate to
confirm that the ambient concentrations of the volatile organic
compounds to be released into the air are in agreement with the
estimates that were calculated for the air stripper operations at
this site. These calculations, based on data from the RI Report,
were designed to provide for the worst case emissions from the air
stripper. These estimated emissions do not exceed the threshold
limits specified by VDAPC regulations.
since none of the emissions from the air stripper are expected
to exceed the exemption levels of the VDAPC's toxics
regulations, monitoring at or beyond the fence line" is not
necessary.
To verify the calculations of the expected emissions from the
67
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air stripper, emissions sampling should be performed at the
air stripper outlet only. Additional monitoring may be
necessary if the monitored emissions exceed the calculated
emission rate.
Based on available information, VDWM identified 16 compounds
found at the site which will be emitted during the air
stripping operations. All of these compounds are VOCs,
specifically they are a mixture composed primarily of
halogenated VOCs, two oxygenated VOCs, two aromatic VOCs and
one sulphur containing VOC. For this mix of VOCs, EPA METHOD
T014 - "DETERMINATION OF VOLATILE ORGANIC COMPOUNDS (VOCS) IN
AMBIENT AIR USING SUMMA PASSIVATED CANISTER SAMPLING AND GAS
CHROMATOGRAPH ANALYSIS" is the recommended analytical
procedure. EPA METHOD T014 has the demonstrated capability to
monitor and analyze for 13 of the 16 identified compounds.
EPA METHOD T014 does not appear to sample and analyze for
acetone, 2-Butanone and carbon disulfide.
The use of EPA.METHOD T014 will provide for the sampling and
analysis of the compounds in the mixture which are emitted in
the greatest amounts or which are the most toxic (ie., lowest
Threshold Limit Value - TLV). Because of the relatively low
emission rates predicted for acetone, 2-Butanone and carbon
disulfide « 1% of the exemption rate), additional monitoring
protocol to sample and analyze for these compounds should not
be necessary.
In summary, use EPA METHOD T014 to monitor emissions at the
outlet of the air stripper to verify the engineering emissions
estimates made for 13 of the 16 compounds. EPA METHOD T014
describes the type of samplers, the analytical methods and
related monitoring protocol.
with regard to monitoring
frequency and duration,
it is
68
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recommended that a one hour sample be taken and analyzed once
a week during the first month of operation of the air
stripper. The test should be performed when the stripper is
running at its projected expected treatment rate of 30 gallons
of water per minute. If the emissions results are consistent,
and do not exceed the engineering estimates previously
provided, then the sampling can be reduced to a one hour
sample and analysis taken once every 30 days for the next 11
months under the same operating and control parameters. If
these emission results are consistent and do not exceed the
engineering estimates previously provided, then the analysis
can be reduced to a one hour sample and analysis taken once
every twelve months.
2. Environmental Monitorinq. An environmental monitoring
plan for the site will be developed. to ensure the effectiveness of
the Remedial Action and to ensure that. the Remedial Action is
protective of human health and the environment. This plan must
address all potentially impacted environmental media. The
monitoring plan shall include, but not be limited to, chemical
monitoring of air emissions, chemical monitoring of groundwater
including monitoring of the onsite 'deep drinking water well, and
chemical/biological monitoring of surface water and sediment. A
terrestrial monitoring program for wildlife (small mammals) and
vegetation impacts shall also be conducted. The plan shall also
include the air monitoring described in Item #1 above under
Monitorinq Performance Standards, stream monitoring as prescribed
by VSWCB as part of the effluent discharge limits set forth in Item
#1 above under Groundwater Treatment Performance Standards, and
groundwater monitoring which meets the relevant and appropriate
requirements of VHWMR ~ 10.5. Also, at a minimum, the influent of
the treatment system will be sampled monthly and selected wells
will be sampled quarterly for volatile organics, metals (target
analyte list), and total cyanide.
69
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~~stitutional Control
Appropriate institutional control measures will be developed
and implemented as part of the remedial action. Insti tutional
control measures would consist of state regulations and/or County
ordinances that prohibit use of water from the contaminated aquifer
until the aquifer has been remediated to acceptable levels.
Cost Estimate of the Selected Remedy
Capital Cost:
Annual Cost:
Present Worth:
$ 1,344,000
$11,833,000
$13,177,000
Remediation Goal
The goal of the response action is to reduce the risks
associated with exposures to contaminated drinking water at the
Site to less than the acceptable levels, Le., 10.6. lifetime
incremental carcinogenic risk and hazardous index of 1. The
cleanup levels for contaminants in the groundwater at the Site are
listed in Table 14. The action levels for contaminants in soils
will be determined during the design phase.
The information collected in the RI/FS indicates that there is
potential to achieve cleanup levels in the groundwater at the site.
However, the extent to which these cleanup levels can be achieved
cannot be determined until the groundwater extraction and treatment
system has been implemented and the aquifer response has been
monitored over time. Periodic monitoring of the aquifer response
during the implementation of the groundwater extraction system may
reveal that groundwater contamination is especially persistent in
the immediate vicinity of the contamination source(s). Monitoring
data collected during the remedial action will be evaluated to
determine the effectiveness of the pump-and-treat system an~ t~
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TABLE 14
CLEANUP LEVELS FOR GROUNDWATER AT THE ARROWHEAD PLATING SITE*
A. ORGANICS (~g/l)
Compound
CleanjtP
Level
Detected Concentration
Range
1,1,1-Trichloroethane
Tetrachloroethene
Trichloroethene
1,1-Dichloroethene
1,2-Dichloroethene (total)
Methylene chloride
1,2-Dichloroethane
1,1,2-Trichloroethane
Benzene
Vinyl chloride
200
S
S
7
b70
Cs
S
Cs
dS
2
10-14S,000
17-26,000
9-21,000
S-(9,8S0)/4,800
7-4,400
S-(200)/9
9-22
6-2S
7
10
B. INORGANICS (~g/l)
Cleanup Fresh Water Drinking Water Detected Cone.
compound Level Criteria e Standards Range (Total),
Cadmium sTBD 0.66 410 3.6-10.8
Copper sTBD S.7 c1,300 1.8-17,400
Nickel sTBD SO clOO 7.S-667
Zinc sTBD 47 fS , 000 6.3-S,600
aFederal maximum contaminant level (HCL) from 40 CFR, Part 141.
bMCL for cis-1,2-dichloroethene.
cProposed Maximum Contaminant Level (PMCL).
dThis HCL goal is below the SW 846 8240 detection limit. Therefore, either EPA method
524.1, 524.2, or 601 will be used to verify the concentration of vinyl chloride in
the ground water. These methods have a 1 ppb detection limit for vinyl chloride.
eVirginia Water Quality Criteria for potection of Aquatic Life (VR680-21-03.2).
fsecondary Haximum Contaminant Level (SHCL).
STBD (to be determined) - Because the drinking water standards for these contaminants
are significantly higher than the corresponding fresh water criteria for the
protection of aquatic life, cleanup levels for these contaminants will be developed
during the remedial design. The established cleanup levels will not exceed the
drinking water criteria as promulgated under the Safe Drinking Water Act. In
addition, the cleanup levels will be established to ensure that the natural discharge
of groundwater from the Site to Scates Branch and its tributaries will not result
in a violation of the fresh water criteria for the protection of aquatic life.
()Concentrations in parentheses are assocaited with tentatively identified compounds.
*Honitoring of Scates Branch at points adjacent to the Site will be conducted to
verify that fresh water criteria for the potection of aquatic life are maintained.
These criteria are identical to the effluent discharge limits established by the
State Water Control Board for the site groundwater treatment system, which are in-
stream criteria based on zero-flow conditions for Scates Branch. If str~am
monitoring indicates that these criteria are being violated, the need for adjustment
to the groundwater cleanup levels will be evaluated. 71
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identify necessary modifications for the treatment scheme. It may
become apparent during the implementation or operation of the
groundwater extraction and treatment that contaminant levels have
ceased to decline. If, even after modifications are made, a
determination is made that it will be impracticable to achieve and
maintain the cleanup levels in the plume or a portion of the plume,
the response action will be re-evaluated. In this event,
groundwater extraction and treatment would continue as necessary to
achieve cleanup levels throughout the rest of the area of
contamination. All of the following measures, including long-term
management, may occur as a response action to address those
portions of the aquifer that are no longer responding to the
existing system:
1)
containment measures such as slurry wall or long-term
gradient control by low level pumping;
2)
waiver of chemical-specific ARARs for the cleanup of
those portions. of the aquifer based on the technical
impracticability of achieving further contaminant
reduction;
3)
continued monitoring of specified wells; and
4)
periodic re-evaluation
aquifer restoration.
of
remedial
technologies
for
With respect to the soil treatment, if the vapor extraction
can not achieve the desired cleanup levels, the effectiveness of
the soil treatment remedy will be re-evaluated with respect to the
levels of contaminants remaining in the soils and the continued
impact of these contaminants to the groundwater. If that
evaluation indicates that the contaminated soils have not been
successfully remediated, then further response action will be
determined and implemented. Options for the response action would
72
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. include,
disposal
for soil
but not be limited to, off site incineration and offsite
of the contaminated soils as stipulated in the discussion
remediation for Alternative 2b.
x. STATUTORY DETERMINATIONS
It is EPA's primary responsibility at Superfund sites to
undertake remedial actions that achieve adequate protection of
human health and the environment. In addition, Section 121 of
CERCLA (42 U.S.C ~ 9621) establishes several other statutory
requirements and preferences. Under this Section, the selected
remedy for the Site, when completed, must comply with ARARs
established under Federal and State laws unless a statutory waiver
is justified. The selected remedy must also be cost-effective and
utilize permanent solutions and alternative treatment technologies
or resource recovery technology to the maximum extent practicable.
Finally, CERCLA includes a preference for remedies that employ
treatment that permanently and significantly reduce the volume,
toxicity or mobility of contamination as their principle element.
This section discusses how the selected remedy meets these.
statutory requirements.
Protection of Human Health and the Environment
Among the risks associated with the Site, the contaminated
groundwater currently poses the most significant risk to human
health and the environment. Through treatment of the contaminated
groundwater, the selected remedy is expected to restore the
contaminated aquifer to beneficial use. The groundwater
remediation is also expected to eliminate discharge of contaminated
groundwater to Scates Branch. In addition, treatment of
contaminated soils at the Site is expected to eliminate secondary
sources of contamination that may act as contributing factors to
the groundwater contamination. These measures would protect human
health and the environment.
73
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All wastes generated as a result of implementation of the
selected remedy will be required to be disposed or treated offsite
and are not expected to pose any environmental or health hazard.
By treating the offgas with carbon adsorption, short-term threats
and cross-media impacts will be eliminated or minimized.
compliance with Applicable or Relevant and Appropriate Requirements
(ARARs) and To-Be-considered Materials (TBCS)
The selected remedy is expected to comply with all chemical-
specific, location specific, and action-specific ARARs, and TBCs.
Those ARARs and TBCs are presented below.
Chemical-sDecific ARARs
1. Relevant and appropriate Maximum Contaminant Levels (MCLs)
promulgated under the Safe Drinking Water Act, 42 U.S.C. ~
300, set forth in 40 CFR Part 141, and proposed MCLs set forth
in the Federal Reqister dated Ju~y 25, 1990, May 22, 1989, and
August 18, 1988, as set forth in Item #2 under Groundwater
Treatment Performance standards, Section IX of this ROD.
Location-SDecific ARARs
1. Any activity to impact on wetlands in close proximity to
the site must comply with the Virginia Wetlands Act, Code of
Virginia ~~ 62.1-13.1 et sea.; virginia Wetlands Regulations
(VR 450-01-0051); Chesapeake Bay Preservation Act, Code of
virginia ~~ 10.1-2100 et~; Chesapeake Bay Preservation
Area Designation and Management Regulations; federal Water
Pollution Control Act, 33 U.S.C. ~ 1344(f) (2) (commonly
referred to as ~ 404 of the Clean Water Act); 33 CFR 323.2(c)
and 33 CFR 323.2(e)i and State Water Control Law, Virginia
Code ~~ 62.1-44.2 et ~
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Action-Specific ARARs
1. Discharge of treated groundwater to Scates Branch will
comply with effluent discharge limits and monitoring
requirements established by the VSWCB in accordance with the
Virginia State Water Control Law, Code of Virginia ~~ 62.1-
44.2 et ~; virginia State Water Control Board Regulations
entitled "Virginia Water Quality Standards" (VR 680-21-00);
the federal Water Pollution Control Act, 33 U.S.C 1251; and
the federal Safe Drinking Water Act, 42 U.S.C. 300(f).
2. Groundwater monitoring in accordance with ~
(VR 672-10-1) will be conducted to monitor the
of the groundwater remedial action.
10.5 of VHWMR
effectiveness
3.
Hazardous wastes to be stored onsite will be stored in
accordance with ~~ 10.8 and/or 10.9 of the VHWMR (VR 672-10-
1) .
4. Transportation of hazardous waste offsite will be in
accordance with VHWMR Part VII and the U.S Department of
Transportation Rules for Transportation of Hazardous
Materials, 49 CFR Parts 107, 171.1-172.558.
5. Air emissions from the groundwater treatment unit and the
soil vapor extraction unit must comply with Virginia Air
Pollution Control Law, Code of Virginia ~~ 10.1-1300 et ~;
the Virginia Department of Air Pollution Control Regulations
for the Control and Abatement of Air Pollution (VR 120-01-01);
the federal Clean Air Act, 42 U.S.C. 7401; and 40 CFR Part 50.
6. Onsite worker safety provisions must be in compliance with
OSHA, 29 U.S.C. 651, and 29 CFR Parts 1910 and 1926.
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To-Be-Considered Materials
1. An air monitoring program will be conducted in compliance
with protocol established by the Virginia Department of Air
Pollution Control as set forth in Item #1 under Monitoring
Performance standards, section IX of this ROD.
2 . Federal Executi ve Order
management (40 CFR 6.302).
11990
related
to
wetlands
3. Endangered species identified to be present onsite or to
be potentially impacted by site activities must be given the
protection afforded by the virginia Board of Game and-Inland
Fisheries, Code of virginia SS 29.1-100 et ~; Virginia
Endangered Species Act, Code of Virginia SS 29.1-563 et sea.;
and the federal Endangered Species Act, 16 U.S.C. 1531.
Cost Effectiveness
The selected remedy is cost-effective because it would provide
a similar degree of permanence and long-term effectiveness as
Alternative 4a, which employs a high efficiency-steam stripping
technique to treat the groundwater, and costs less (13.2 million as
opposed to 15 million dollars). The No-Action Alternative can be
implemented at a much lower cost, but it does. not provide for
permanent treatment, protect human health and the environment.
Also, or meet ARARs.
utilization o~ Permanent Solutions and Alternative
Technologies to the Maximum Extent Practicable
Treatment
The Commonwealth and EPA have determined that the selected
remedy represents the maximum extent to which permanent solutions
and alternative treatment technologies can be utilized in a cost-
effective manner to control contamination at the Site. The
76
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selected remedy also provides the best balance of tradeoffs among
the other evaluation criteria including long-term effectiveness and
permanence; short-term effectiveness; reduction in toxicity,
mobility and volume through treatment; implementability;
state/support agency and community acceptance; and preference for
treatment of contaminated water and soils as a principle element.
By extraction and treatment of the contaminated groundwater
with air stripping and carbon adsorption, and by treatment of the
contaminated soils with soil vapor extraction, the principle risk
at the Site is expected to be significantly reduced, resulting in
acceptable risk levels. The selected remedy, therefore, has been
determined to be the most appropriate alternative for the Arrowhead
Plating Site.
Preference for Treatment as Principal Element
By treating the contaminated groundwater and soils. at the
Site, the selected remedy satisfies the statutory preference for
remedies that employ. treatment as a principal element to
permanently reduce the toxicity, mobility and volume of the
contamination.
XI. DOCUMENTATION OF SIGNIFICANT CHANGES
The Proposed Plan, released for public comment in July 1991,
identified Alternative 2a as the preferred alternative. Although
this ROD selects this alternative, review of the Proposed Plan and
new information have resulted in the following significant changes.
o
The Proposed Plan specified groundwater cleanup levels for
cadmium, copper, nickel, and zinc as 0.4, 1000, 100, and 50
ppb respectively. Upon further evaluation by VDWM and
consultation with VSWCB and EPA, it was determined that these
proposed cleanup levels may not be appropriate, and cleanup
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levels for the above inorganic contaminants will be determined
during the remedial design as noted in Table 14. This
determination was made to allow for the establishment of
cleanup levels that meet drinking water standards and ensure
the protection of aquatic life from natural discharge of
groundwater from the Site to Scates Branch and its
tributaries.
The Proposed Plan indicated that treatment of offgas generated
by both the groundwater remedy and the SVE process would be
collected and treated if necessary. It has been determined
that the offgas will be collected and treated by carbon
adsorption prior to discharge to the atmosphere to minimize
media transfer of contamination.
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