United States Office of
Environmental Protection Emergency and
Agency Remedial Response
EPA/ROD/R03-91/132
September 1991
&EPA Superfund
Record of Decision:
Arrowhead Associates/Scovill,
VA
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50272-101
REPORT DOCUMENTATION 11. REPORT NO. I ~ 3. Rec:lplenr8 ~an No.
PAGE EPA/ROD/R03-91/132
4. TII8 8IId Subft8 5. Report D818
SUPERFUND RECORD OF DECISION 09/30/91
Arrowhead Associates/Scovill, VA
First Remedial Action - Final e.
7. Aulhor(.) 8. PWrfonning Org8lllza1lon Aept. No'
.. Parfonnlng Orgalnlz81lon Nanw and Add.... 10. ProJactlT88IIIWortI Unit No.
-
11. ConIr8ct(C) or Gr8nI(G) No.
(C)
(G)
1~ ~ng Organlz8llan Nanw and AcIdre88 13. Type of Rapor1. Pwltod Covered
U.S. Environmental Protection Agency 800/000
401 M Street, S.W.
Washington, D.C. 20460 14.
15. ~ No..
1e. Abalr.ct (Urnlt: 200 worda)
The 30-acre Arrowhead Associates/Scovill site is a cosmetic-case manufacturing and
filling facility in Westmoreland County, Virginia. Land use in the area is
predominantly agricultural, with several businesses. Also, woodlands and wetlands
areas are located proximal to the site. There is a small stream, Scates Branch,
that originates on site and flows to an offsite pond and creek. The site overlies a
shallow aquifer that is used by an estimated 500 people as a drinking water supply.
Ownership of the site has changed hands several times. From 1966 to 1979, Scovill,
I~c., and later Arrowhead Associates (AA), used the site for manufacturing cosmetic
cases using electroplating, lacquering, and enameling processes. Once the plating
process was complete, the solutions were discharged to onsite settling ponds.
Supernat~nt from these ponds was either reused or discharged to surface water.
Bottom wastes and small amounts of other spent materials were stored in drums for
subsequent offsite disposal. After 1979, site operations switched to cosmetic-case
filling, and subsequently to wire harness manufacturing. Currently, Virginia
Elastics uses the former plating area as a storage warehouse. Numerous
investigations by the State and EPA revealed extensive soil and ground water
(See Attached Page)
17. Docum8nI An8Iy8I8 .. D88crIpCora
Record of Decision - Arrowhead Associates/Scovill, VA
First Remedial Action - Final
Contaminated Media: soil, gw
Key Contaminants: VOCs (benzene, PCE, TCE, toluene, xylenes) and metals (chromium,
b. Idanllfl8r8lOpen-Endad T8f1I18 lead)
c. COSA n Fl8ld/Group
18. Av_1abl1ity ~ 18. SeaIri1y CI... (Th18 Repor1) 21. No. of P8gea
None 84
20. SecurIty CI... (ThI8 Page) ~ PrIce
None
ANm-Z38.18 SH /Mtructi- on Rs-
(See
(Formetty HTIS-35)
D8par1man1 of Comnwce
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EPA/ROD/R03-91/132
Arrowhead Associates/Scovill, VA
First Remedial Action - Final
Abstract (Continued)
contamination. From 1986 to 1988, EPA conducted a two-phased removal action at the
site. Phase I of the removal, conducted from 1986 to 1987, included removal of wastes
and various contaminated materials. Phase II, conducted from 1987 to 1988, consisted
of treating and disposing of wastewaters, sludge, and soil from the former settling
ponds, and offsite disposal of contaminated soil from a drum storage area. In 1990,
the ponds were filled and graded, and erosion control measures were installed. This
Record of Decision (ROD) addresses final remediation of soil and ground water. The
primary contaminants of concern affecting the soil and ground water are VOCs including
benzene, PCE, TCE, toluene, and xylenes; and metals including chromium and lead.
The selected remedial action for this site includes implementing in-situ vacuum
extraction of VOC-contaminated soil; onsite pumping and pretreatment of contaminated
ground water using pH adjustment, precipitation, flocculation/sedimentation, and
filtration, followed by treatment using air stripping and carbon adsorption, and onsite
discharge of the treated water to Scates Branch; disposing of residual sludge and
residues from the ground water treatment process offsite; treating off-gases from the
soil and ground water treatment systems using carbon adsorption; and implementing
environmental monitoring, and institutional controls including ground water use
restrictions. The estimated present worth cost for this remedial action is
$13,177,000, which includes an annual O&M cost of $11,833,000.
PERFORMANCE STANDARDS OR GOALS: Chemical-specific soil clean-up goals will be
determined during the remedial design. Chemical-specific ground water clean-up goals
are based on SDWA MCLs and include benzene 5 ug/l, PCE 5 ug/l, and TCE 5 ug/l.
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RECORD OF, DECISION
ARROWHEAD PLATING SUPERFUND SITE
MONTROSS, VIRGINIA
PREPARED BY
VIRGINIA DEPARTMENT OF WASTE MANAGEMENT
SEPTEMBER 1991
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TABLE OF CONTENTS
PART I - DECLARATION
...... ........... ......................
Page
1
I.
II.
III.
IV.
V.
site Name and Location ..........................
Statement of Basis and Purpose ..................
Assessment of the Site ..........................
Description of the Selected Remedy..............
Statutory Determinations ........................
2
2
2
2
4
PART II - DECISION SUMMARY
I.
II.
III.
IV.
V.
VI.
VII.
VIII.
IX.
X.
XI.
. ................................
5
site Name and Location .......................... 6
Site History and Enforcement Activities ......... 9
Highlights of community Participation ........... 10
Scope and Role of Response Action .~............. 13
Summary of Site Characteristics ................. 14
Summary of Site Risks...................... ~ . . .. 23
Description of Alternatives ..................... 39
Summary of Comparative Analysis of Alternatives. 48
Selected Remedy and Performance Standards ....... 54
Statutory Determinations ........................ 73
Documentation of Significant Changes ............ 77
PART III - RESPONSIVENESS SUMMARY
I.
II.
III.
IV.
. . . . . . . . . . . . . . . . . . . . . . . . .. 79
An Overv-iew ..................................... 80
Background of Community Involvement ............. 81
Summary of Public Comments and Responses ........ 85
Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 90
i
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LIST OF TABLES
Table 1 -
Table 2 -
Table 3 -
Table 4 -
Table 5 -
Table 6 -
Table 7 -
Table 8 -
Table 9 -
Table 10 -
Table 11 -
Page
Site Chronology............................ 11
Summary of Chemicals of Concern for the
Arrowhead Plating Site ..................... 21
Exposure Parameters Used to Estimate
Inhalation Exposures for Workers Inside
The Manufacturing Building at the
Arrowhead Plating Site ..................... 26
Exposure Parameters Used to Estimate
Exposures for Future Residents Ingesting
Groundwater at the Arrowhead Plating Site :. 26
Exposure Parameters Used to Estimate
Inhalation Exposures for Future Residents
at the Arrowhead Plating Site .............. 27
Exposure Parameters Used to Estimate
Dermal Contact Exposures for Future
Residents at the Arrowhead Plating Site .... 28
Exposure Parameters Used to Estimate
Soil Ingestion Exposures for Future
Residents at the Arrowhead Plating Site .... 29
Exposure Parameters Used to Estimate
Dermal Contact Exposures for Children
Wading in Surface Water at the Arrowhead
Platinq Site............................... 30
Exposures Parameters Used to Estimate
Dermal Contact Exposures for Children
Contacting Sediment at the Arrowhead
Platinq site............................... 31
Chronic Oral Toxicity Values for
Chemicals of Potential Concern ............. 33
Chronic Inhalation Toxicity Values for
Chemicals of Potential Concern ............. 34
ii
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Page
Table 12 - Potential Risks Associated with Current
Inhalation Exposure at the Arrowhead
Plating Site............................... 36
Table 13 - Summary of Excess Lifetime Cancer Risks
and Hazard Indices for the Arrowhead
Plating Site ............................... 37
Table 14 - Cleanup Levels for Groundwater at The
Arrowhead Plating Site ..................... 71
LIST OF FIGURES
Figure 1 - Site Location .............................. 7
Figure 2 - Site Layout................................ 8
Figure 3 - Geologic Cross Section B-B ................. 16
Figure 4 - Extent of Total VOCs in Groundwater ........ 18
Figure 5 - Groundwater Extraction, Treatment,
and Discharge Process Schematic ........;... 42
APPENDICES
Appendix A:
Appendix B:
Appendix C:
Appendix D:
Appendix E:
Description of Evaluation Criteria
community Reiations Activities Outline
Additional Information
Glossary of Superfund Terms
Index of Documents for The Administrative
Record
iii
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PART I
DECLARATION
1
-------
DECLARATION
I. SITE NAME AND LOCATION
Arrowhead Plating
Montross, Virginia
II. STATEMENT OF BASIS AND PURPOSE
This decision document presents the remedial action selected
for the Arrowhead Plating Superfund Site (Site), located in
Montross, Virginia, which was chosen in accordance with the
Comprehensive Environmental Response, compensation, and Liability
Act of 1980 (CERCLA), as amended by the Superfund Amendments and
Reauthorization Act of 1986 (SARA), and the National Oil and
Hazardous Substances Pollution contingency Plan (NCP). The
decision contained herein is based on information included in the
Administrative Record for this Site. An index of documents for the
Administrative Record for this Site is included in Appendix E.
Both the Commonwealth of Virginia Department of
Management (VDWM) and the Environmental Protection Agency
support the selected remedy.
Waste
(EPA)
III. ASSESSMENT OF THE SITE
Actual or threatened releases of hazardous substances from
this site, if not addressed by implementing the remedial action
selected in this Record of Decision (ROD), present an imminent and
substantial endangerment to public health, welfare, or the
environment.
IV. DESCRIPTION OF THE SELECTED REMEDY
The
selected
remedial
action
addresses
contaminated
2
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groundwater and contaminated soils that act as secondary sources of
contamination. The major components of the selected remedy
include:
o
A groundwater extraction network to remove contaminated
groundwater from the aquifer for treatment;
o
precipitation of
extracted water;
the
inorganic
contaminants
from
o
Treatment of organic contaminants in the extracted water
by air stripping and carbon adsorption;
o
Discharge of the treated water to
stream originating onsite and
Millpond and Pierce Creek;
Scates Branch, a small
flowing into Weavers
o
Defining the extent of contamination in the soils and in-
situ vapor extraction of volatile organics in the
cQntaminated soilsi
o
Capture and treatment using carbon adsorption of offgas
from treatment trains for soils and groundwater prior to
discharge to the atmosphere;
o
Implementation of an environmental monitoring plan to
evaluate the effectiveness of the remedial action and to
ensure the protection of environmental receptors in
Scates Branch; and
o
Implementation of appropriate institutional control
measures prohibiting the use of contaminated groundwater
to ensure protection of public health and the
environment.
3
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V.. STATUTORY DETERMINATIONS
The selected remedy is protective of human health and the
environment, complies with Federal and State requirements that are
legally applicable or relevant and appropriate to the remedial
action, and is cost effective. By treatment of contaminated
groundwater and soils at the site, the selected remedy utilizes
permanent solutions and alternative treatment technologies to the
maximum extent practicable, and satisfies the statutory preference
for remedies that employ treatment that reduces toxicity, mobility,
or volume as a principal element.
During the implementation of the selected remedy, the
contaminants in the groundwater could remain at concentrations
above health-based levels. Consequently, a review will be
conducted within five (5) years .after the commencement of the
remedial action to ensure that the remedy continues to provide
adequate protection of human health and the environment.
UNITED STATES
ENVIRONMENTAL PROTECTION AGENCY
~~
~/a() /1/
Date
t, Edwin B. Erickson
~. Regional Administrator, Region III
VIRGINIA
DEPARTMENT OF WASTE MANAGEMENT
~/r/
,
Date
Director
4
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PART II
DECISION SUMMARY
5
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I~ SITE NAME AND LOCATION
The Arrowhead Plating Site is located two miles southeast of
the Town of Montross, Virginia. This town is located in
Westmoreland County, which is a part of Virginia's Northern Neck
r~gion, situated between the Rappahannock and Potomac Rivers.
The Site occupies approximately 30 acres of land on the east side
of State Route 3 in Westmoreland County (Figure 1). The western
portion of the Site consists of a one-story brick manufacturing
building, a parking lot, and an 817-foot-deep well, which supplies
drinking water to the workers. The eastern portion of the site
,covers an area of five former sludge settling ponds and a treated
wastewater pond. currently, two sewage water treatment ponds are
located near the eastern edge of the property. These ponds are
used to treat sanitary wastewater generated by the facility. In
addition, one chlorinated solvent tank and one acid tank are
located along the northern edge of the facility; both are above-
ground and empty. Figure 2 depicts the major features at this
Site. .
Bordering the site is Chandler's Chevrolet dealership to the
south, the Manning and Meinhardt Garage and Montross Hardwood to
the north, agricultural land and woods to the east and agriculture
land to the west. Approximately 47% of the land in Westmoreland
County is used for agricultural purposes. The population of the
Town of Montross is about 500, and the majority of the residents
are located more than one mile west and north of the Site.
Groundwater is the only source of drinking water for the Site
and the surrounding area. The shallow groundwater aquifer flows
towards Scates Branch and the South Fork Scates Branch. Surface
waters within a three-mile radius of the site are used primarily
for recreational purposes. No irrigation of agricultural land in
the vicinity of the site reportedly occurs.
6
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~\f
~
o
I
SCALE 1 :24000
1/2
~
Figure 1
.:..
Site Location
Arrowhead Plating SIte
11.11LE
!
-l ~
Source: u.s. Ceparlment 01 !1'18 Interior. G.QlogicaI Survey. l.IonlrOSS Cuadrangle. Virgirn. 7.5-minUt8 tcpograDntc 1968.
ptIOlDI'8Yised 1981.
~
POOR QUAUTV
ORIGINAL
7
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FIGURE 2 - SITE LAYOUT
I
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NEW I
POND AGRJC~;UIW.
FlE'-O
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SE'NAGE:
L.-\GOON
SEWAGE:
LAGOON
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APPROXIMATE
LOCATION OF
OIL-SiAINEO .
SOILS
.15528
o PUIoIPHOIJS£
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TOWER
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L. FORMER DRUM
--.y SiORAGE: AREAS
OkJ4
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SSJ6
COMMU1tR
PARKING LOT
MONTROSS -
US ROUTE 3
. SURFACe: SOIL ~UNG LOCATION (O-a-)
r- PROPERTY UNE
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...--
. INTEUo4rrTANT CRAINACE
r-- FENCe:
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-
ARROWHEAD PLATING SIT'E:
MONTROSS. VIRGiNIA
---
Ict mSER ENGINE1RS
.... . AUGUSi 1991
sc:.u: IN fur
8
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. . II. SITE HISTORY AND ENFORCEMENT ACTIVITIES
1. site Historv
Westmoreland Industrial Development Corporation originally
procured the land and constructed the manufacturing building. The
property was leased to Scovill Inc. (Scovill) in 1966. In 1972,
Arrowhead Associates (Arrowhead) purchased the business and
facility assets, and subsequently subleased the property from
Scovill. In 1983, Arrowhead reopened business under new ownership
as the A.R. Winarick Company.
From 1966 to 1979, the facility manufactured cosmetic cases
using electroplating, lacquering and enameling processes. Most of
the cases were either brass- or zinc-plated with a small portion of
the cases silver-plated. Copper,. zinc, cyanide, and acid and
alkali solutions were used in these plating operations, while a
chlorinated solvent was used for degreasing prior to lacquering or
enameling plated cases. During this period, wastewaters from the
brass, zinc, and silver electroplating operations were conveyed to
a treatment system located inside the manufacturing building for
oxidation and neutralization prior to discharge to the onsite
settling ponds. Supernatant from these ponds was either reused in
the plant or discharged to Scates Branch unde~ a National Pollutant
Discharge Elimination System (NPDES) permit. Chlorinated solvents
were recovered by distillation of the spent solvent generated by
the degreasing process. Still bottom wastes and small amounts of
other spent materials were accumulated in drums that were
periodically shipped offsite for management at another Scovill
facility. In 1979, Arrowhead Associates terminated these
manufacturing operations and switched to cosmetic-case filling
operations, which are still being performed at the facility. Also
in 1979, use of the five sludge settling ponds and the treated
wastewater pond was terminated.
9
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In the early 1980' s, Mattatuck Manufacturing began
manufacturing automobile wire harnesses at the Site and in 1988,
Virginia Elastics started using the former plating area as
warehouse space.
2. Enforcement Activities
In July 1986, Scovill and EPA Region III entered into an
Administrative Order on Consent that required Scovill to conduct a
two phase removal action. Phase I action, from December 1986 to
September 1987, removed wastes and contaminated materials including
residual process wastes, drums, damaged tanks, interior piping, and
deteriorated concrete inside the manufacturing building. During
Phase II action, which began in November 1987 and continued until
November 1988, approximately 395 cubic yards of contaminated soils
from the former drum storage areas were removed offsite. Phase II
action also consisted of treating and disposing of wastewaters,
sludges, and soils in the former settling ponds. In April 1990,
filling and grading of the pond areas occurred, and erosion control
measures were installed in October 1990.
The Site was proposed to the National Priority List (NPL) in
June 1988, and finalized on the N~L in February 1990. In July
1989, Scovill entered an Administrative Order on Consent with VDWM
to conduct a. remedi~l investigation/feasibility study (RI/FS),
which characterizes the extent-an~nature of contamination at the
site, and identifies remedial alternatives. The RI/FS work plan
was approved in February 1990. Table 1 includes a chronology of
Superfund actions at the Site.
-
III. HIGHLIGHTS OF COMMUNITY PARTICIPATION
The primary issues of concern to most Montross-area residents
include issues that affect the Nomini Creek, Chesapeake Bay or
local waters and wetlands; agriculture; maintaining the natural
10
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TABLE 1 - SITE CHRONOLOGY
- ^*^DAlX'-1lM|'*'vi:?SlTE OPERATOR/AcnVTlY DESCRIPTION OF EVENT --V 'V".-
1966-1972 ScovilL Inc. Electroolated cosmetic cases.
1972-1979
1979
1979-1983
Early 1980s-
present
1983-oresent
March 1985
July 1985
Feb. 1986
Feb. 1986
July 3, 1986
.Dec. 1986-
Fsb. 1987
Sept. 1987
Nov. 1987
Arrowhead Assoc.
Arrowhead Assoc.
Arrowhead Assoc.
Mattatuck Manufacturing
A.R. Winarick
Scoviil Internal Site Assessment
Scoviil Site Assessment (con-
ducted bv Law Environmental)
Commonwealth of Virginia (De-
partment of Health)
Preliminary Assessment
U.S. EPA ERT Site Inspection
Consent Agreement and Order
Phase LA Initial Wasie Remov-
al
Phase IB Interior Geaaup
Phase IIA Soil Removal
June 1988 1 Prooosed NPL Lfsons
Juiy-Nov. 1988
1988-oresent
Julv 14. 1989
Apt-June 1390
Match 1990-
*WV^^»^M« +
JEfiSCQt
Phase ITB Pond Abatement
Virginia Elastics
Administrative Order bv Consent
Coomietioa of Pood Closure
RJJES
Electroolated cosmetic cases.
Ceased electroDiarins ooerations.
Filled cosmetic cases.
Fabricates automobile wire
harnesses.
Fills cosmetic cases.
Internal report disclosing findings and
recommending an investigation be con-
ducted.
Results of assessment shared with
state.
Site inspection conducted after meet-
ing with Scovfll to review July 1985
assessment (no sampling conducted).
Resulted in "Preliminary Assessment"
reoort dated Mar. 25. 1986.
At VADWM's reouest and followins
VADWM's site inspection, U.S. E?A
ERT conducted their site inspection
(no samolins conducted).
Agreement to conduct a two-phase
Immediate Removal Action.
Removal of residual process wastes,
drums, and damaged process tanks.
Removal c£ interior piping,
tfetencrated concrsie. etc.
Rsmoved sofl fiuzn drusa srorage ar-
eas. ,
Listed on orooosed NPL.
Removal of wastewaters, sludges, and
soils from settlin? oonds.
Warehouse (in former piarnig areaX
Aereemen: to conduct the RJ/FS.
Fffled and graded fonner pond areas.
(Additional erosion controls unoie-
nm»rf in Oct 1990L)
RI condocaed to x^**** nature and
rsrrnt of cfieancais; FS c-f>n"«c"r-rf tG
evaluate ieniqfijil afternarfves.
11
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beauty of the area; and 'the recent influx of people from the
Northern virginia area who are buying land around Nom.ini Creek, and
what impact this development will have on the area. The
Westmoreland Environmental Council has taken an active role in
addressing these issues and has shown interest in Superfund
activities at the Site.
community members played an important role in the compilation
of the community Relations Plan (CRP), which was drafted in
January, 1990. One month later, residents were notified that the
RI/FS work plan had been approved. Throughout the RI/FS, updates
on site activities were provided on a quarterly basis and VDWM
responded to questions from residents and officials. On June 12,
1990, VDWM conducted an RI/FS workshop for area residents. The
purposes of the workshop were to discuss the Superfund program,
explain the activities conducted in the RI/FS, and inform community
members of the current site status.
As activities in the RI/FS stage progressed, VDWM maintained
communications with. community members and determined that an update
to the Community Relations Plan was needed. Many residents in
Montross were contacted to assess changes in interest levels
concerning the Superfund activities at the Site. Two months later,
Community relations staff from VDWM came into the community to
address the Westmoreland Environmental Council. This served as an
opportunity to present the Superfund Program in detail and answer
any questions.
In according with CERCLA ~ 113(k) (2) (B) (i-v) and ~ 117(a), the
Proposed Plan was drafted, based on the results of the RIfFS, and
its availability for review was announced in the July 25, 1991
edition of The Fredricksbura Freelance Star and Westmoreland News.
This same public notice also publicized the start of the Public
Comment Period on July 26~ 1991 and the public meeting held at the
American Legion on August 6, 1991. The public comment period ended
12
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. . August 26, 1991.
At the public meeting, representatives from VDWM presented an
overview of the Superfund process, a summary of the Proposed Plan,
and answered questions from community members. EPA officials were
also present to address any of the residents' concerns. A formal
response to questions and comments put forth during the public
meeting and comment period can be found in Part III of this
document, the Responsiveness Summary. community participation
activities such as additional meetings, per request, and quarterly
mailings will continue through the remedial design/remedial action
.phase for the Site. A detailed outline of Arrowhead community
relations activities can be found in Appendix B.
All documents utilized in the determination of site activities
can be found in the Administrative Record located in the office of
the County Administrator on Peach Grove Lane, Montross, Virginia.
An index of these documents are included in the in Appendix E.
IV. SCOPE AND ROLE OF RESPONSE ACTION
The Remedial Investigation Report for the site documents the
actual and potential releases of hazardous substances into the
environment and the risks posed by the site. The existing
principal risk associated with the site was determined to be the
organic contamination of the shallow, unconfined aquifer. This
contamination poses a threat to the deeper aquifer. Groundwater is
the only drinking water source for residents in the area.
Additionally, discharge of contaminated groundwater to the nearby
Scates Branch has impacted the aquatic life in the stream. It is
an expectation of the NCP that groundwater will be remediated to
its benef icial uses. The goal of this response action is to
restore the groundwater to beneficial use by achieving cleanup
levels whenever practicable.
13
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In addition to the contaminated groundwater, contaminated
soils at the Site also present a threat associated with
contaminant releases from the soils into the groundwater. Since
most of the contaminated soils were removed during Phase II
Removal, the remainder of the contaminated soils at the Site acts
as a low-level threat. The remedial action selected in this ROD is
expected to address the remainder of the contaminated soils to
prevent contaminants from leaching into the groundwater, thereby
facilitating the groundwater treatment process.
v. SUMMARY OF SITE CHARACTERISTICS
This section discusses site hyqrological and geological
characteristic, identifies areas of concern, summarizes the
sampling results obtained during the RIjFS, and discusses major
fate and transport phenomena concerning the contaminants found at
the Site.
1. Site Characteristics
Local geology was characterized by a soil survey for
Westmoreland County and the onsi te deep water supply well. Soil in
the Montross area is identified as Suffolk sandy loam having 10
inches of brown sandy loam overlying 40 inches of sandy loamy sand.
Surface soil samples taken during the RI ranged from clayey silts
to sandy silts with some organic matter. Approximately 40 feet of
the top sediment belong to the Bacons Caste Formation, a thin bed
composed of laminated clayey silt and silty fine sand with local
sandy intervals. The underlying 200 feet of strata belongs to the
Upper Chesapeake Group formations, including the Yorktown and
Eastover formations; these formations contain interbedded and
poorly sorted clay, silt, and sand. Between 240 feet and 340 feet
below the ground lies the lower Chesapeake Group formations, which
are dominantly sand, shells, and silts.
14
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within the Bacons Caste Formation, heterogenous mixtures of
sand, silt, and clay exist. Silt, .coarse sand and gravel, and clay
lenses are common while fine and medium sand are the most abundant
grain sizes in this unit. A discontinuous layer of cemented sand
was also encountered. The observed thicknesses of this formation
range from 0 feet in the Scates Branch, where it has been
completely eroded, to 40 feet (Figure 3). Underlying the Bacons
Caste Formation is a clay-rich continuous layer that belongs to the
Upper Chesapeake Group. This layer, considered the bottom of the
shallow aquifer, is a hydraulic boundary through which there is no
significant flow of groundwater. This layer can be observed in the
bottom of Scates Branch and along the walls of the valley of Scates
Branch where the contact between the Bacons Caste and
Yorktown/Eastover formations outcrops.
The shallow, unconfined aquifer exhibits a great deal of
heterogeneity. In general, permeability varies over short
distances, and the soils are more permeable in the horizontal
direction than in the vertical direction. Slug tests conducted
during the RI indicated a range of horizontal hydraulic
conductivities from 9x10.' to 5. 4X10-3 ft/min with an arith~etic
-3 .
average value of 2.7xlO ft/m~n. Depths to groundwater occur from
2 to 22 feet below the ground surface. Groundwater discharges to
both Scates Branch and the South Fork Scates Branch (Figure 3) with
an average velocity of 0.21 ft/day. Typically, the potentiometric
surface of the groundwater table of an unconfined aquifer displays
a subdued expression of the surface land topography. As Figure 3
indicates, the closer a location is to the Scates Branch or its
tributaries, the lower the groundwater table. A groundwater divide
probably exits near state Route 3, and another is present on the
property and continues into the agricultural field east of the Site
where groundwater discharges to different branches of Scates
Branch.
15
-------
::J'
Cf)'
~
,~
'--"
z
o
~
~
UJ
- 110
hi-I - 100
-to'W
" (X r-
" ~ 00
" " (X
"
)<
"
00
FIGUI{E 3
GEOLOGIC CROSS SECTION B-B'
ARROWHEAD PLATING SITE
B
318'
160' -1- 00' -1- 1M' -1- 122' -I
225'
150
SQ/LIW2
IS'E
til\JLIW2I
140
SII/I.IWIO
SlI/LIW12
130
SII/LlWI3
110
IDO
~
A A ;«Y ~~('A
XXXXA,<;: "
"""'IlOXIt.IA1E 1:1 [VA1IOt~ Atln l1I1Cl
-------
2. Areas of Concern
Areas
of
concern
identified
in
the
RI/FS
included
the
chlorinated solvent tank, the former drum storage areas, the former
ponds areas, the acid tanks area, the drainage lines, and the
stained area (Figure 2). These area are discussed below.
Chlorinated Solvent Tank. The solvent tank is located outside
the northwestern corner of the manufacturing building. It was
installed horizontally upon 4-foot high concrete supports.
with a capacity of approximately 1,200 gallons, it was used
from around 1966 until 1980 or 1981. The solvents stored in
the tank were conveyed into the manufacturing building through
an underground piping system. According to a registration
report submitted to the virginia Department of Air POllution"
Control (VDAPC), trichloroethene (TCE) was stored in the tank
until 1973; "Chlorothane," possibly containing 1,1,1-
trichloroethane (l,l,l-TCA), was stored until 1979; and
"Perconne 2," possibly containing perbhloroethene (PCE), was
stored later. "Groundwater underneath the "tank contained the
highest concentration of total volatile organics (VQCs) found
in the aquifer underneath the Site, indicating the tank or the
underground piping was a primary source of groundwater
contamination at the Site (Figure 4). The tank was emptied
during the Initial Waste Removal.
Former Drum storaqe Areas. It is estimated that these areas
were used for drums storage from late 1970's to 1985. During
the removal actions, Scovill conducted offsite removal of
approximately 270 drums containing waste solvent and paints,
electroplatinq waste sludges and cosmetic production wastes,
or rain water. Siqns of leakage and visual evidence of
releases onto the soils in these areas were observed. Also
removed were soils contaminated with cyanide, chromium,
copper, and zinc. An action level of 2 mg/kg of cyanide in
17
-------
FIGURE 4
EXT~NT OF TO~~L VOCs
IN
GROUND
\I" ---
/I ,:.:., i::..~
~
~
-
-
Q
...
-
-
..'
...
-
~
j
t,
:
,
.'
.I'
."'...
~
(
.J
,~~
. .;J \ I
'/ '"
( ...~../- - I
" -.I \ .
,t \
"'---'--
) ....
,.
. /
... I -
",,- - - - - -
I - f"
" I - --
I ,:..---_----
...
. /
II
:1
.... I'
.",..... I
~ '..t
...... I '.
'";11") :.-... ...
I --------
I!
i
i
.
i
i
i
!
;
~
<~
~
".,
~,
...J
<1:
Z
-
~
a:
o
'.....
. '.
"
I~-
us I!C\IrE ~
-~"I
r- c-..HT'.IoIoI1HAHT ~
cna-- -. M_)
(C-__.-._- it -)
r-- CIIOU_~ !l...<'VAt1OH
. CD- -. i"'_)
(~ .. t_)
-&
4
~ W!IJ.
SUf'..a WAT!K SAWJIU:
.-- p~ t.DIC ~ 1C11
.-- ~ -..-
~ =~~ ~RCWf-!S~D ?!.AT.1NG Si7::11
a::::::I FORWR PCr«! AAEA I MCNT~OSS. Vl~G:N!A
ZZZJ ~£R ~W ~ Nw. rICl 71'SIR lNr;~m1'.s I
~ ~-;;ICUNQ ~ :-- (ASTI .-. :3 I 9 I
('- 1- ...-- -- =-) '~..;
-------
the soils was achieved in these areas. These areas,
particularly the large drum' storage area, may also have
contributed to the VOCs contamination in the groundwater at
the Site as a result of leakages from drums that were stored
in these areas.
Former Ponds Areas. Each of the five former sludge settling
ponds (approximately 8-10 feet deep), and the former treated
wastewater pond (about 4-6 feet deep) received wastewaters
from the electroplating operation, which contained significant
amounts of copper, zinc, cyanide, silver, lead, and possibly
chromium. The sludges in these ponds were removed offsite
during Phase II Removal, and the areas have been graded and
vegetated. The RI data indicate that inorganics compounds
were not widespread in soils or groundwater underneath these
areas, only small pockets of inorganic contamination appear to
remain.
Acid Tanks Area. Two 5,000-gallon tanks were used to store
nitric acid and sulfuric acid. They were located along the
north side of the manufacturing building just outside the
former electroplating area. This area was investigated to
determine if spillage had occurred.
Drainaqe Lines. The drainage lines were used to convey the
treated wastewater to Scates Branch. It is possible that
overflow from the former wastewater ponds or from the drainage
lines occurred, resulting in infiltration of contaminants into
the qroundwater.
The 81:ained Area. Located near the northern edge of the large
drum storage area, this area contained dark stained soils. A
spill of chemicals could have occurred in this area,
indicating a potential source of contamination.
19
-------
3. SamDlina Results
A summary of chemicals of concern found during the RI/FS in
each of the areas discussed above is presented in Table 2.
Surface soil sampling results did not indicate widespread
distribution of VOCs and inorganics of concern. VOCs and metals
were detected at elevated levels in the drum storage areas and in
one sample near the solvent tank area. Cyanide was found at high
concentrations in a few samples from the drum storage areas. Semi-
VOCs were detected in a few samples at concentrations well below
the health-based levels of concern.
Regarding subsurface soil contamination at the Site,
analytical results indicate no widespread contamination, but
significant contaminant levels were found at several locations.
VOCs were present at high concentrations in the small and large
drum storage areas and in one soil boring drilled in the location
of the former new pond. Elevated VOCs levels were encountered at
or below the groundwater table in many cases. High levels of
inorganics were encountered mostly in the former pond area, while
cyanide concentrations in all subsurface soil samples were
generally low (less than 2 mg/kg). No semi-VOCs were detected in
the subsurface soils.
As Figure 4 shows, the groundwater contamination associated
with VOCs at the Site is extensive and significant. The
contamination plume extends offsite and into Scates Branch and the
South Fork Scates Branch where groundwater discharges to the
surface system. Primary VOCs of concern include PCE, 1,1,1-TCE,
and associated degradation products including 1,1-dichloroethene
(l,l-DCE), and 1,2-dichloroethene (1,2-DCE). Vinyl chloride is
also an end product of chlorinated ethane degradation, and has been
detected at the detection limit level (10 ppb) in one sample. No
semi-VOCs were detected in the groundwater. Although some metals
20
-------
TABLE 2
SUMMARY OF CHEMICALS OF CONCERN FOR THE ARROWHEAD PLATING SITE
Surfac:e Soi l
.......----.....-........................
C:-~ Ac:id Solvenc Orain S".c-
Storage Tani( Tani( I.ines S:ained Surfac:e C;-ound Surfac:e
C~!!IIic:al Areas Area Area Area "rea Soi l '.later I.a ce~ S eo: i tI'.e~~
Or;anic:s:
.........
~c!,=cne X X X X X X
Sen:oic: ac:id X
Sis(2-e:~ylhexyl)cnthalace X X X X X
C3r:cn :etrac:~lorice X X
l.-C."loroani line X
C:1lorofor:n X
1, 1.~ic:~lor~etnane X
1, '-~ic:~loroe:~ene X
',2-~i~~loroe:~ene (total) X X X X
Oi-~-~cylpnc~alace X
~ecnyl e::1yl ketone X X X X
~e:nylene c:~lorice X X X
Phenant"rene X
iec;-ac:nloroe:hene X X X X X X X
iol!.:ene X
',', '-iric:~loroetnane X X X
Tric:;,loroe:hene X X X X
Xylenes C:ocal) X
[norganic:s:
...-.----.
Aluninun X X X X X X X
3ariun X X' X X X X
Caaniun X X
Calciun X X X X X X X X
C."romiun X X X X X X
Coc:cer X X X X X X X
Cyanide X X X X X
II"'0n X X X
I.ead X X X X X X
l1er:l.lry (inorganic) X X X X
Nic:itel X X X X X X X
1'0 cass i un X X X X X X X
Si lver X X X
Sodiun X X X X X X X X
tine: X X X X X X
X a Selr-:ed as I ~;,u:mic:al 0+ pocential e:cncem in chis mediun.
21
-------
~ere detected in the groundwater at levels above applicable
standards, metal contamination in the groundwater at the Site is
limited and localized. Cyanide was found at low levels in several
onsite wells and two offsite wells, but cyanide contamination is
much more limited than the VOCs plume.
The sampling results also indicate that VOCs in the
groundwater are discharged to the surface water in Scates Branch
and its tributaries; however, VOCs were present only in upstream
locations. Elevated metal and cyanide levels also occurred
sporadically. Surface water in Weavers Millpond was found not to
be impacted by the site. In the sediments, low levels of VOCs were
detected in upstream samples while no significant concentrations of
semi-vOCs or metals were detected. Cyanide was not detected in any
sediment samples taken from Scates Branch or Weavers Millpond.
4. Fate and Transport
Major transport mechanisms at this Site include (1) runoff of
surficial soils into surface waters; (2) vertical migration of
conta~inants into groundwater through soils; (3) advection and
dispersion of contaminants within the aquifer; and (4) groundwater
discharge to surface water. Migration of contaminants via
volatilization of contaminants from soil and via suspended
particles were determined to be insignificant.
Key factors influencing the VOCs migration at the Site are:
(1) the relatively high solubilities of the VOCs of concern; (2)
the permeable sandy soils; (3) the flow of groundwater; and (4) the
presence of an impermeable layer at the bottom of the shallow
aquifer, which prevents vertical migration of contaminants. VOCs
released from the solvent tank, underground piping, and from the
large drum storage area appear to have migrated downward through
soils into the groundwater, where advection, dispersion and natural
degradation occur. Although the subsurface contamination in these
22
-------
. ' areas has not been fully defined, high concentrations of VOCs of
concern are possible and could act as ongoing residual sources for
many years to come as contaminants migrate into groundwater through
rain water percolation. In addition, dense, nonaqueous-phase
liquids (DNAPLs) may exist in the subsurface or in the aquifer.
Because DNAPLs are heavier than water and immiscible, they can form
a distinct layer in the groundwater that act as an ongoing source
of contamination. Plumes of individual VOCs of concern appear thin
and parallel to the groundwater flow directions (eastward with
branching to the southeast and northeast), indicating that the VOCs
are probably moving at approximately the same rate as the
,groundwater, and that the VOCs are probably not significantly
retained in the aquifer. As groundwater seeps into the surface
system at the interface along the walls of Scates Branch and its
tributaries, VOCs are transported as solutes, with dilution,
dispersion and volatilization causing rapid concentration decrease
in surface water.
Metals found in the groundwater' at the site did not display
any distinct p~tterns. In soils above the groundwater table,
metals contamination occurred sporadically. Since metals are
charged species that adsorb readily to clay particles, sediments,
and organic materials, most are relatively immobile in soils and
groundwater. Among the metals of concern, zinc and copper are of
significance. cyanide is another inorganic of concern, and appears
in the groundwater east of the manufacturing building with a
distribution more distinct than that of the metals. Cyanide was
present at levels well below the Proposed Maximum contaminant Level
(PMCL) of 200 /Jg/l, and its occurrence in the groundwater was
localized.
VI. SUMMARY OF SITE RISKS
Human health and environmental risk assessments were performed
with information obtained from the remedial investigation and other
23
-------
background information. The risk assessment was conducted in
accordance with EPA risk assessment guidance for Superfund (OWSER
Directive 9285.7-01a, 9/1989). The human health risk assessment
consists of four major steps: identification of chemicals of
concern, exposure assessment, toxicity assessment, and risk charac-
terization.
Xdentification of chemicals of concern. After review of the
collected data, all potentially site-related organic chemicals were
selected as chemicals of concern (Table 2). For inorganics, only
those compounds that are present at concentrations above the
corresponding background levels were selected. The background
concentrations were determined from samples taken at upgradient
locations. Table 2 includes the chemicals of concern for the Site
in different media. VOCs make up the majority of organic chemicals
of potential concern.
Exposure Assessment. Currently, the closest residential area
is approximately one mile away. No public or private recreational
areas are located near the Site. Consequently, trespassing is
likely to be infrequent. As the Site is an active commercial
facility, the primary human receptor population of the
contamination is the employees of the facility. The RI identified
several potential exposure pathways includi~g present and future
land use scenarios for the human populations potentially exposed to
the contamination at the Site. It is possible that the Site could
be developed into a residential area in the future. The following
are exposure pathways considered significant in the risk assessment
for the site.
CUrrent land use conditions: VOCs that have volatilized from
contaminated surface soils and transported indoors where
workers spend most of their time could result in inhalation
exposures of relatively long duration;
24
-------
Future land use conditions: it is possible that futUre
residents would be exposed to the contamination by (1) using
the contaminated groundwater for drinking purposes, resulting
in exposures via ingestion; (2) inhalation of VOCs of concern;
(3) dermal contact of contaminated soils; (4) incidental soil
ingestion; and (5) children wading in surface water and
contacting sediments and surface water.
Exposure parameters for different
presented in Tables 3 through 9.
exposure
pathways
are
Toxicity Assessment. EPA has classified chemicals into two
distinct categories of chemical toxicity depending on whether they
exhibit carcinogenic (cancer-causing) or noncarcinogenic effects.
Health effects criteria have been developed for risk assessment
purposes and are discussed below.
For estimating excess lifetime cancer risks associated with
exposure to potentially carcinogenic chemicals, EPA has developed
slope factors, expressed in u~its of (mg/kg-day)", to calculate an
upper-bound estimate of the excess lifetime cancer risk associated
with exposure to these chemicals. The term "upper bound" reflects
the conservative estimate of the risk calculated from the slope
factor. Use of this approach makes underestimation of the actual
cancer risk highly unlikely. Slope factors are derived from the
results of human epidemiological studies or chronic animal
bioassays to which animal-to-human extrapolation and uncertainty
factors have been applied. The extent to which a given substance
is carcinogenic in humans is reflected by the weight-ox-evidence
assigned to that substance. A weight-of-evidence classification is
determined by experimental or epidemiological studies involving
exposure to the substance in question with "A" meaning high
confidence and "E" meaning that there is no evidence of
carcinogenicity from exposure to the substance.
25
-------
7.-\BE 3
::<;lOS''';i(E ~~i(~"'E::~S USE::: ~::J :~~,."A~:
.!I""u ~ :C!I ::
-------
TAELE 5
e:(POSUlle ~~IU."E:E~S USE~ iO ES':-:!4AiE !!lMAUi:C!I
::(PCSURE~ rCI! .::.JTUl!e~E~:O::fTS
AT in: ARR~.HE~O ~~AiI!lC S,iE
Pa...ameter-
Vall.:e
Innalation ~ate
18 m3/cay (8)
;65 c3ys/year- (:)
e~~sur-e F...ecuenoy
Year-s or E~~sur-e
;0 yea...s (':)
loa ki (0)
Ave...age Sody ~ei;nt Ove...
=.'~sUt"e ile...iod
(a) ~ei;"ted ave~age to... i~iv;Cuals 1-30 yea...s
baSed on IIRC? (198') ana E?A (19850) ~ata.
(~) Sas~ en :?A (1989a).
(e) hSed~e?A (i9890>.
or ac;e
POOR QUALITY
ORIGINAL
27
-------
TABLE 6
EXPOSURE ?ARA«S?s?.S USED TO = ";«A7= CEr.MAL CCNTACT
EXPOSURES ?CR -UTURE SEilOEMTS
A" THE ASSCVHSAO PLATING SITE
Parameter Value
Soil Cantact Sate 9,430 mg/«y (a)
Atsoraticn ractar
VCCs 0-1 9/c3i2 (SPA 1989a).
(b) Assuneo value basec an analogy ta otner cr.enicals
and wemieal-pnysical properties.
-------
TABLE 7
EXPOSURE PARAMETERS USED TO ESTIMATE SOIL INGESTION
EXPOSURES FOR FUTURE RESIDENTS
AT THE ARROWHEAD PLATING SITE
Parameter
Value
Ingestion Rate
120 mg/day (a)
Fraction of Ingested Soil Which
is from Contaminated Areas
1 (a)
Organic Chemicals:
Bis(2-ethylhexyl)phthalate
All others
0.5 (b)
1. 0 (c)
Frequency
152 days/year (d)
Years of Exposure
30 years (a)
Average Body Ueight Over
Exposure Period
48 kg (e)
(a) Based on EPA (1989a).
(b) Estimated based on 2,3,7,8-TCDD (Poiger and Schlatter 1980,
McConnel et al. 1984, Lucier et al. 1986, Uendling
et al. 1989, and van den Berg et al. 1986, 1987).
(c) Assumed value.
(d) Based on NOAA (1978) data collected at Richmond, VA.
Assumes that residents spend time outdoors from March
through October (279 days, or 40 weeks), and that
children up to 12 years of age play outdoors 5 days/week,
and individuals over 12 years of age are outdoors
3 days/week.
(e) Based on EPA (1989b). Average for individuals
1-30 years of age.
29
-------
TAB L::: 8
E:UilF"~ '".l.iEi!
~i iae Ailil~JHeAO "~Ai:)lG s.ie
Parametar
VallJe
SlJrrace Area EA~seci
5, ~ao c::'.2 (a)
Oer::lal
"er::lelai l i ':;'/
C~;anic ~~enic3ls
C'{anice
Inor;anic C~emicals
O.CCOS ==vhr (:)
o.oooa c=/hr (:)
o ==vhr (e)
:Ap05ure DlJrar:cn
2 ~ours/~y
Ii Cays/year (c)
:.t~osure Fr~/!!!C'I
Years aT E~~csl.lre
" years Ce)
31 kg (T)
Average 30ey \oIei;;,r Over
E.'~slJre Pericc:
.'
Ca) ;ased an :?~ C198Sb). Surface area Of hanes, ar~,
fae~, ana La;s for 0-12 year old c~ildren.
(~) 3asec an :?~ (~989a). Assumes thac a(l or;anie
eh~ie3ls ~e~e~rare s~in at same rare 15 water.
Cyanide also is (nown :0 pe~e~rare sxins ana is
ass~ :0 :e~et~lte sxin ar :~e same rare as warer.
(c~ Qe~~l ~r~4IoiLi:y of inorganic c~emicals is ass~~
ro ce ~e9~igi~le.
Ca) Assumes :~a: childre~ 0-12 ye!rs wade in warer
:3 cays/w~k Curing monc~s wnen averaqe caily ~~erl'
:~re is aver 650F Co ,non:hs: Acril - Se::~r).
(e) Assumes cililcr~ '.ade in sti"eam from Iqe 0:0 aqe 1,.
(f) 3asec on ;?~ (i9891). Average Qocy weigilr for
children 0-12 years old.
30
-------
n.BLE 9.
;:(~CSU~; ?~~.1M;;;:;S USE;) TO ;:;T!~Ar: ~e~.~"1. C:!li.1C7
:::
-------
For chemicals with the potential to cause adverse health
effects other than cancer, EPA has developed levels that human,
including sensitive subpopulations can be exposed to on a long-term
daily basis without experiencing any adverse effects. These levels
are called reference doses (RfDs), and are expressed in units of
mg/kg-day. Estimated intakes of chemicals from environmental media
(e.g., the amount of a chemical ingested from contaminated drinking
water) can be compared to the RfD. RfDs are derived in a similar
fashion to slope factors. uncertainty factors help ensure that the
RfDs will not underestimate the potential for adverse
noncarcinogenic effects.
Table 10 and 11 present health effects criteria for chemicals
of concern found at the Site.
Risk Characterization. Excess lifetime cancer risks are
determined by multiplying the intake level with the slope factor.
These risks are probabilities that are generally expressed in
scientific notation (e.g., 1X10-6, or 0.000001). An excess lifetime
cancer risk of 1X10-6 indicates that, as a plausible upper bound,
an individual has one in one million chance of developing cancer as
a result of exposure to a carcinogen over a 30-year period under
the specific exposure conditions at a site. EPA considers a total
cancer risk at Superfund sites acceptable if the risk is 1x10-6 or
less. However, depending on site-specific circumstances, a risk
-6 -4
within the range of lxlO to lxlO may also be acceptable.
Risks associated with exposures to noncarcinogens is expressed
as a Hazard Index (HI), which is the ratio of the long-term daily
exposure rate (typically called the chronic daily intake) to the
RfD. The overall HI is the sum of the ratios of chronic daily
intakes to the RfDs for all chemicals under consideration. The
overall HI provides a useful reference point for gauging the
potential signi~icance of multiple contaminant exposure within a
single medium or across media. In general, hazard indices that are
32
-------
TABLE 10
CHRONIC ORAL iOXIC,iY VALUES FOR CHEMICALS OF ?OTE~TIAL C:NC;~N
Chemical
Chronic Reference
Oose (mg/kg-day)
(Uncertainty
Factor] (a)
Reference
Oose
Source
Cancer
SlaDe Factor
(rng/kg-day)-t
USE?A IJei Sip:
or e'/idence
Classification
(c)
Slol:)e
Factor
Source
.........
Organics
Acetone
Benzoic acid
Sis(2-ethylhexyl)phthalate
Car:on tet~achloride
C:-.lororor:ll
1,1-Qichloroethane
" t-Dicnloroethene
1.2-Qichloroethene (total)
Oi-n-outylcnthalate
~ethylene chloride
Methyl ethyl ketone
?henanthrene (e)
ietracnloroethene
1.1.1-irichloroethane
Trichloroetnene
Inor;anics
...-......
Aluminum
Barium
Cac:mium (tood)
(water)
Calcium
C~rcmium (n)
C.:::cer
'yanice
ron
Lead
Mercury (inor;anic)
Nickel
?otassium
Sitver
S"dium
Zinc
Tarset Organ (b)
o
o
a2
32
32
C
C
o
o
B2
o
o
32
o
a2
o
o
B1
81
o
o
o
Q
o
B2
o
o
o
o
o
o
I~IS
I~rs
,~I S
[~IS
HeAS7
I~IS
i~IS
I~[S
I~IS
IiUS
HeAS7
IRIS
HEAS7
[~IS
[~IS
I.US
IRIS
:.~ I S
I~IS
i~ IS
1e-Ot (t000] liver. Ie idney IRIS
t.E.OO (1] Irritation IRIS
2:-02 (1000] Liver IRIS 1.t.c-02
7E-0t. (10001 Liver IRIS t.3E-01
te-02 (1000] Liver IRIS 6.te-03
te-01 (1000] Kidney HEAST (d)
9E-03 (10001 Liver IRIS 6e-01
2:-02 (1000] Blood serum IRIS
1E-Ot (iOOOI Mortal icy IRIS
6e-02 (t001 Liver IRIS 7.5E-03
5E-02 (t0001 (f) Fetus IRIS
t.E-03 (i00001 eye IRIS
1e-02 (10001 Liver IRIS 5.1E-02 (g)
ge-02 (1000] Liver IRIS
7.35E-03 (10001 Liver HA 1. 1E-02
7E-02 (31 Blood pressure IRIS
1 E-03 (101 Kidney IRIS
5e-0t. (101 Kidney IRIS
5E-03 (5001 Nervous syscem IRIS
3.7E-02 (i) GI HeAST
2e-02 (500] ThyrQ id IRIS
3e-0t. (10001 Kidney HeAST
2: -02 (3001 Body weight IRIS
3E-03 (21 Argyria (skin) IRIS
2E-01 (101 Anemia HEAST
(a) Uncertainty factors used to develo~ reference doses generally consist of multiples of to, with each factor re~resenting a
specific area of uncertainty in the data available. The standard uncertainty factors include the following:
- A to-fold factor to account for the variation in sensitivity among the members of the human ~o~lation:
- A 10-fold factor to account for the uncertainty in extra~lation animal data to the case or h~ns:
- A iO-rold factor to account for uncertainty in extrapolating frOD less than chronic HOAELs to c~ronic
NOAeLs; and
- A 10-fold factor to account for the uncertainty in extrapolating fran LOAELs to NOAe~s.
(b) A target organ is the organ most sensitive to a chemical's toxic effect. RfO's are based on toxic effects in the target
organ. I f an RfO was based on a study in wnic:."1 a target organ was not identified, an organ or system known to be affected by
tne chemical is listed.
(c) E?A 'Jeight of Evidence for c.rcinogenic Effects: [AI. Human carcinogen based on ad~ate evidence frQIII hunan
studies: [B2] .. Probable hunan carcinogen based on inadequate evidence trOD hunan studies and adec;uace evidence from
animal s:ucries: (C] .. Possible hunan carcinogen based on limited evidence from animal studies in tne absence or hunan
studies: [0] .. Not classified as to hunan carcinogenicitY: and (EI .. evidence or noncarcinogenicitY.
(d) IJithdrawn by e?A.
(e) ioxicicy criteria for naphthalene are used in the absence of criteria for phenanthrene.
(t) aased on route to route extra~lation. Being reconsidered by the RtO workgroup.
(g) Under review by, CRAVe workgroup.
(h) Toxicicy criuria reported is tor c!lraniun VI, IS all c:."IrODiun is conservatively assuned to be in the form of
c:.,romiun VI.
(i) Drinking water standard reported in mgfl is converted to mgfkg-day by assuning a 70 kg adult consunes Z liters
or water per day.
NOTE:
IRIS
HEAST
HA
E?A
.. Inteegrated Risk Information System - OCtober " 1990
. Heal th Effects Assessment S&mII8ry Tables - July '. 1990
.. Orinking ~ater Health Advisory
. environmental Protection Agency
.. No information available
POOR QUALITY
ORIGINAL
33
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TABLE 11
CHRONIC INHALATION TOXIC"? VALUES ?GR CHEMICALS Qf POTENTIAL CCHCS3N
Chemical
Organ ics
Chronic Reference
Dose (mg/kg-day)
CUncertainty
factor)
-------
not greater than one (1) are not likely to be associated with any
health risks.
Under the current land use conditions, inhalation of volatile
chemicals in ambient air by onsite workers is the only existing
exposure pathway. The Site presents an upper-bound excess lifetime
cancer risk of 1X10'7, and the associated overall HI for
noncarcinogenic risks is less than 1 (Table 12).
For the future potential residential land use scenario, only
risks associated with use of contaminated drinking water in the
aquifer underneath the Site are of concern. The estimated upper-
bound excess lifetime risk is 8X10'2, indicating an unacceptable
risk to human health, and the associated overall HI is greater than
one (Table 13), indicating the risks of adverse noncarcinogenic
effects such as liver and kidney damage are unacceptable. The
reason for the high risk is the heavily contaminated groundwater
beneath and downgradient of the Site as shown in Figure 4. The
contaminants include numerous VOCs, the major ones being 1,1,1-
trichloroethane, trichloroethylene (TCE), and tetrachloroethylene
(PCE). Combined concentrations of VOCs ranged as high as 180,850
parts per billion (ppb). Under the Safe Drinking Water Act (42
U.S.C. ~ 300), safe levels or Maximum contaminant Levels (MCLs)
have been set to protect humans. For 1,1,1-trichloroethane, the
MCL is 200 ppb. The MCL for TCE and PCE are 5 ppb. Of the major
contaminants, TCE and PCE are considered by EPA to be probable
human carcinogens.
Some of the contaminants found in groundwater were also
detected in soils. Areas of contamination include an above-ground
chlorinated solvent tank area, drum storage areas, and a former
lagoon. These areas could be contributing to contamination of the
groundwater through the downward migration of VOCs or the leaching
action of infiltrating rainwater. The risk resulting from human
contact with the contaminated soils was found to be minimal due to
35
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TABLE 12
?OT;)lT:-'L illSX:S ASSCC:-'TE!) IoI[TH C'..iRRe)lT [HHAL-'i.CN ;;
-------
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
-------
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
-------
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.
61
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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).
64
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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.
66
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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~
70
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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
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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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