United States Office of
Environmental Protection Emergency and
Agency Remedial Response
EPA/ROD/R04-90/074
September 1990
Superfund
Record of Decision
SCRDI Bluff Road, SC
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50272-101
REPORT DOCUMENTATION
PAGE
1. REPORT NO.
EPA/ROD/R04-90/074
3. Recipient^ Accession No.
1. TWe and Subdue
SUPERFUND RECORD OF DECISION
SCRDI Bluff Road, SC
First Remedial Action - Final
5. Report Date
09/12/90
7. Authors)
8. Performing Organization Rept No.
». Performing Organization Name end Addreaa
10. Project/T**k/Work Unit No.
11. Contrect(C) or Grant(G) No.
(C)
(G)
12. Sponsoring Organization Name and Address
U.S. Environmental Protection Agency
401 M Street, S.W.
Washington, D.C. 20460
13. Type of Report ft Period Covered
800/000
14.
IS. Supplementary Notes
16. Abstract (UmH: 200 words)
The 4-acre SCRDI Bluff Road site is an inactive chemical waste manufacturing, storage,
recycling, and disposal facility in Richland County, South Carolina. Surrounding land
use is rural residential and industrial, and part of the site has been classified as a
wetlands area. The site was first used as an industrial facility, which manufactured
cetylene gas. Two lagoons were constructed onsite to support this operation. Starting
n 1975, the site was used as a storage, recycling, and disposal facility for chemical
waste. An above-ground storage tank was installed for use in these processes. All
operations at the site ceased in 1982 after State investigations identified onsite soil
and ground water contamination. From 1982 to 1983, the State addressed the site
contamination and required the removal of over 7,500 drums containing various chemicals,
visibly contaminated soil, and above-ground structures. Additionally, in 1989, the
storage tank containing approximately 100 gallons of contaminated sludge was removed.
This Record of Decision (ROD) addresses remediation of both the contaminant source and
ground water, and provides a final remedy for the site. The primary contaminants of
concern affecting the soil and ground water are VOCs including benzene, toluene, PCE,
TCE, and xylenes, other organics including PCBs, phenols, and pesticides; and metals.
(See Attached Page)
17. Document Analysis a. Descriptors
Record of Decision - SCRDI Bluff Road, SC
First Remedial Action - Final
Contaminated Media: soil, gw
Key Contaminants: VOCs (benzene, PCE, TCE, toluene, xylenes), other organics (PCBs,
pesticides, phenols), metals
b. Mentiftera/Open-Ended Terms
c. COSATI Held/Group
18. Availability Statement
19. Security Class (Thi» Report)
None
20. Security Class (This Psge)
None
21. No. of Pages
112
22. Price
(See ANSI-Z39.18)
See Instruction* on Reverse
OPTIONAL FORM 272 (4-77)
(Formerly NTIS-35)
Department of Commerce
-------
EPA/ROD/R04-90/074
SCRDI Bluff Road, SC
First Remedial Action - Final
Abstract (Continued)
The selected remedial action for this site includes pumping and onsite treatment of
ground water using flocculation/precipitation as a pretreatment to remove metals, air
stripping to remove VOCs, and granular activated carbon adsorption to remove
semi-volatile organic compounds, if necessary, followed by reinjecting the treated
water onsite; treating contaminated soil in-situ using vacuum extraction, followed by
carbon adsorption or fume incineration to destroy off-gases; managing carbon
residuals from ground water and soil treatments through offsite disposal or
regeneration; and monitoring soil and ground water. The estimated present worth cost
for this remedial action is $5,574,984, which includes an annual O&M cost of $311,287
for 16 years.
PERFORMANCE STANDARDS OR GOALS: Cleanup standards for ground water are the more
stringent of Federal or State MCLs or proposed MCLs. Chemical-specific ground water
goals include benzene 5 ug/1 (MCL), PCE 5 ug/1 (MCL), TCE 5 ug/1 (MCL), toluene
2 mg/1 (MCL), and xylenes 10 mg/1 (MCL). Soil cleanup levels were calculated using a
soil leachability model (SL). Chemical-specific goals for soil include benzene
12 ug/kg, (SL) PCE 53 ug/kg, (SL) TCE 18 ug/kg (SL), toluene 17.4 mg/kg (SL), xylenes
69.5 mg/kg (SL), and phenol 3.95 mg/kg (SL).
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RECORD OF DECISION
REMEDIAL ALTERNATIVE SELECTION
SCRDI BLUFF ROAD SITE
COLUMBIA, RICHLAND COUNTY
SOUTH CAROLINA
PREPARED BY:
U.S. ENVIRONMENTAL PROTECTION AGENCY
REGION IV
ATLANTA, GEORGIA
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DECLARATION FOR THE RECORD OF DECISION
SITE NAME AND LOCATION
SCRDI Bluff Road Site
Columbia, Richland County, South Carolina
STATEMENT OF BASIS AND PURPOSE
This decision document represents the selected remedial action
for this site chosen in accordance with CERCLA, as amended by
SARA, and to the extent practicable, the National Contingency
Plan. This decision is based on information contained in the
administrative record file for this site.
The State of South Carolina concurs on the selected remedy.
ASSESSMENT OF THE SITE
Actual or threatened releases of hazardous substances from this
site, if not addressed by implementing the response action
selected in this ROD, may present an imminent and substantial
endangerment to public health, welfare, or the environment.
DESCRIPTION OF THE SELECTED REMEDY
This remedy addresses the source of contamination to groundwater
(contaminated soil) and the contaminated groundwater present at
the site.
The major components of the selected remedy include:
GROUNDWATER
- Extraction of contaminated groundwater
- On-site treatment of extracted groundwater
Pretreatment for metals removal
Air stripping
Liquid phase granular activated carbon system
Vapor phase activated carbon system (emissions control)
- Discharge of treated groundwater via reinjection
- Groundwater remediation will be performed until all
contaminated water meets the cleanup goals specified in
the attached Summary of Alternative Selection
SOIL
- Installation of a network of air withdrawal (or vacuum)
wells in the unsaturated zone
- Construction of a pump and manifold system of PVC pipes
used for applying a vacuum on the air wells to remove the
organic compounds from soil
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-2-
STATUTORY DETERMINATIONS
The selected remedy is protective of human health and the
environment, attains Federal and State requirements that are
applicable or relevant and appropriate, and is cost-effective.
This remedy satisfies the statutory preference for remedies that
employ treatment that reduces toxicity, mobility, or volume as a
principle element. Finally, it is determined that this remedy
utilizes permanent solutions and alternative treatment
technologies to the maximum extent practicable. Because this
remedy will not result in hazardous substances remaining on-site
above health based levels, the five-year facility review will
not apply to this action.
C\ ^ \\ 1 ^-~..r
Gteer C. Tidwe^ll
Regional Administer
ScP 1 2 19=3
Date
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SUMMARY OF REMEDIAL ALTERNATIVE SELECTION
SCRDI BLUFF ROAD SITE
COLUMBIA, RICHLAND COUNTY
SOUTH CAROLINA
PREPARED BY:
U.S. ENVIRONMENTAL PROTECTION AGENCY
REGION IV
ATLANTA, GEORGIA
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TABLE OF CONTENTS
1. 0 Introduction 1
1.1 Site Location and Description 1
1. 2 Site History 1
2 . 0 Enforcement Analysis 4
3 . 0 Community Relations History 4
4 . 0 Scope of Response Action 5
5 . 0 Summary of Site Characteristics 5
5 .1 Hydrogeological Setting 5
5 . 2 Site Contamination 6
5.3 Risk Assessment Summary 20
6 . 0 Clean-up Criteria (ARARs ) 25
6 .1 Chemical Specific ARARs 25
6 . 2 Location Specific ARARs 25
6 . 3 Action Specific ARARs 36
6.4 Other Criteria, Advisories and Guidance 36
7 . 0 Documentation of Significant Changes 36
8 . 0 Alternative Evaluation 37
8 .1 Alternatives 37
9.0 Summary of Comparative Analysis of Alternatives 78
10.0 Selected Remedy 83
10.1 Description of Recommended Remedy 84
10.2 Cost of Recommended Alternative 87
10.3 Schedule 88
10.4 Future Actions 88
11.0 Statutory Determinations 88
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FIGURES AND TABLES
Figure 1 Site Location Map
Figure 2 Bluff Road Site Diagram
Figure 3 Shallow Aquifer Plume
Figure 4 Surface Soil Contamination
Figure 5 Subsurface Soil Sampling Locations*
Figure 6 Extraction Well Locations
Table 1 Groundwater Summary - Organics
Table 2 Groundwater Summary - Metals
Table 3 Surface Soil Summary - Volatiles
Table 4 Surface Soil Summary - Semi-volatile
Table 5 Surface Soil Summary - Pesticides/PCBs
Table 6 Surface Soil Summary - Me s
Table 7 Subsurface Soil Summary - Volatile Organics
Table 8 Subsurface Soil Summary - Semi-volatile Organics
Table 9 Subsurface Soil Pesticides/PCBs
Table 10 Subsurface Soil Summary - Metals
Table 11 Wet Lagoon Sediment Summary - Organics
Table 12 Wet Lagoon Sediment Summary - Metals
Table 13 Groundwater Cleanup Criteria
Table 14 Soil Cleanup Criteria
Table 15 Wet Lagoon Sediment Cleanup Criteria
Table 16 .Action Specific ARARs
Table 17 To Be Considered Criteria Advisories and Guidance
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1.0 Introduction
1.1 Site Location and Description
The SCRDI Bluff Road Site is a four acre parcel of land located
in Richland County, South Carolina and is approximately 10 miles
south of the City of Columbia on the north side of State Highway
48. (Figure 1) The site is a rectangular parcel of land
measuring 133 feet of frontage on Bluff Road (Highway 48), and
extending back from the road approximately 1,300 feet. (Figure
2) The site is relatively level with ground elevation varying
from approximately 139 feet near the highway to 134 feet above
mean sea level at the rear of the property. The front portion
of the site, extending to approximately 600 feet from the road,
is cleared and has been used for various industrial and
commercial purposes. The back portion of the site, encompassing
one half of the area, is heavily wooded. Surrounding and
adjacent properties are wooded and rural. The nearest
residences are approximately a mile away.
The soils identified in the project by the Richland County Soil
Survey include loams, which are mixtures of sand, silt, and
clay. The specific soil types present in the vicinity of the
site are Orangeburg loamy sand, Persanti very fine sand loams,
Smithboro loam, and Gantry loam. A low permeability surface
clay layer was predominant in areas adjacent to the site.
The local hydrogeology pertinent to the site is defined by a
surficial aquifer and a deep aquifer with the two formations
separated by a clay aquitard. The shallow aquifer typically
extends to a depth of 45 to 50 feet and is composed primarily of
sands which range from coarse and well sorted to silty and
poorly sorted. This aquifer has been classified as a potable
aquifer by the State of South Carolina. The ground water table
in the shallow aquifer generally lies 10 to 15 feet below ground
surface based on the three rounds of ground water level
measurements taken. The deep aquifer is separated from the
shallow aquifer by a clay and silt unit which ranges in
thickness from 1.5 to 25 feet. This partial confining layer is
thinnest upgradient of the site and thickens to the south and
west. The State still has a question as to whether or not the
clay layer is continuous over the area of the site. This will
be resolved during the Remedial Design development. The
lithology of the deep aquifer is similar to that of the shallow
aquifer, though clay-rich layers are more common. Both the clay
aquitard and the deep aquifer are thought to be units in the
Black Creek Formation.
Most of the nearby property and rear portions of the site have
been classified by the Corps of Engineers as wetlands. A
Westinghouse Nucleur fuel rod manufactoring plant is located
across Bluff Road. Current use of the Site and nearby
properties is rural and wooded (with the exception of the
Westinghouse plant). Future use of the property is likely to be
light industrial development.
-1-
-------
ro
I
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**•.'( v-l/'/''
_, /
I nr.iiinn ol '•«•• Ki'laiivr in Major
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II M M^t .1 |M* M«r.»
' v>4
I I*
\, ' - ' /"• \^( ^l/ui-' N
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-. ' )r. - r rKTri.I /I V-\\ VJ^ I
y vx^^v[\^>v
^^^'Ci\i;/^^
,,
\
FIGURF. 1
BLUFF ROAD SITE
VICINITY LOCATION
-------
I
OJ
I
SCRDI SITF
r *^ -. . - ^•
^ J __ rf__
^v. r£MP<
OFFICE TRAILER
NEW TRUCK
DECON PAD
1M< It CO«»O»«"OM
• it ro"«Miii
WOOPFn AREA
CAMPBELL'S GARAGF PROPERTY
OLO CAMPBELL
~I HOUSE (REMOVFO)
I I
L-J
x x
NOFCNCC
BLUFF ROAD SITE DIAGRAM
TO
... Ci»nllno a SoUi Tomonaw
FIGURK 2
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1.2 Site History
The first reported use of the si-te was as an acetylene gas
manufacturing facility. Specific dates and other details
regarding the facility operations are not available. However,
two lagoons were constructed at the north end of the cleared
area of the site to support acetylene manufacturing.
In 1975, the site became a marshalling center for Columbia
Organic Chemical Company. Columbia Organic Chemical Company
funded the operations of Bluff Road which used the site
beginning in 1976 to store, recycle, and dispose of chemical
wastes. The site was closed in 1982 after a ground water
investigation conducted by the South Carolina Department of
Health and Environmental Control (SCDHEC) and EPA revealed the
presence of site contamination of soils and groundwater.
A surficial cleanup of the site was performed in 1982 and 1983.
Over 7,500 drums containing various chemicals were removed from
the site for disposal. Visibly contaminated soil and all above
ground structures were removed from the site. Clean fill and
gravel were placed on the site to fill in excavations and
provide clean roads. The two lagoons and an above ground tank
containing approximately 100 gallons of sludge were left
on-site. This above ground tank was removed in 1989 as part of
the RI/FS at the site.
2.0 Enforcement Analysis
The Bluff Road Site is ranked 83rd on the National Priorities
List by the U. S. Environmental Protection Agency under the
Comprehensive Environmental Response, Compensation and Liability
Act (CERCLA). The site is also listed as the top priority site
in the State of South Carolina. Special notice letters were
sent to approximately one hundred thirty-nine potentially
responsible parties to give them the opportunity to conduct the
RI/FS. An Administrative Order on Consent to perform the RI/FS
was entered into by a group of forty-three of the PRPs on April
21, 1988.
3.0 COMMUNITY RELATIONS
An information repository for this site was established in the
Landmark Square Branch of the Richland County Library on
Garner's Ferry Road in Columbia, South Carolina. Information is
also available in Atlanta, Georgia, in the EPA Region IV
Regional Office. Fact sheets and press advisories were prepared
prior to each public meeting. Prior to the Feasibility Study
Public Meeting, a public notice ran in the local newspaper (The
Stated.
A public availability session was held on June 1, 1989 to
discuss the site status. A Community Relations Plan identifying
a positive public outreach strategy was developed at the
-4-
-------
direction of EPA Region IV staff and submitted to the repository
in October 1988. Another availability session was held November
2, 1989 in the Hopkins Community Center to present and discuss
the findings of the Remedial Investigation. A Public Meeting
was held on April 10, 1990 in the Hopkins Community Center to
present to the public the findings of the Feasibility Study
Report and to present the Agency's preferred alternative. This
meeting also opened the public comment period. During the
initial thirty day public comment period, a request for an
extension was received by the Agency. The public comment period
was extended an additional 30 days. The public comment period
ended on June 10, 1990. The comments received are addressed in
the Responsiveness Summary.
4.0 Scope of Response Action
The remedial action addressed by this ROD will prevent current
or future exposure posed by this site. The action will remove
the threat posed by contaminated groundwater at the site and
will remediate the soil so that it no longer acts as a
continuing source for the groundwater contamination. This is
the only ROD contemplated for the site. No other operable units
have been identified as necessary at this site.
5.0 Summary of Site Characteristics
5.1 Hydrogeological Setting
The stratigraphy of the study area may be divided into four
hydrologically connected water-bearing units underlying the
site. Hydrogeologic units are as follows:
o A shallow, surficial aquifer in the Okefenokee terrace,
underlain by a clay or sandy clay aquitard, part of the
Black Creek Formation
o A deep aquifer consisting of sand and clay, also part of
the Black Creek Formation, underlain by another aquitard
of sandy clay
o The deepest aquifer, the Middendorf Formation,
consisting of sand, silt, and clay (which many
geologists call the Tuscaloosa Aquifer)
o The crystalline pre-Mesozoic basement which has
virtually no primary porosity but possibly has
significant high secondary fracture porosity.
-5-
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5.1.2 Local Hydrogeology of.the Shallow Aquifer
The shallow aquifer typically extends to a depth of 45 to 50
feet and is composed primarily of sands which range from coarse
and well sorted to silty and poorly sorted. It is semiconfined
by a resistent layer composed of varying amounts of clay, silt,
and sand which usually lies from the surface to a depth ranging
from 5 to 15 feet.
The ground water table in the shallow aquifer generally lies 10
to 15 feet below ground surface based on the three rounds of
ground water level measurements taken. The overall ground water
flow is approximately to the east. The gradient of the
potentiometric surface is about 0.003 near Bluff Road and
flattens dramatically to less than 0.001 in the vicinity of
MW-4, MW-6, MW-8, and MW-12. The Remedial Investigation data
indicate that there is a downward head in the surficial aquifer
and it could recharge the deeper aquifer. The surface in this
area is very irregular and flow patterns are subject to local
influences. Overall discharge may be to Myers Creek.
5.1.3 Local Hydrogeology of the Deep Aquifer
The deep aquifer is separated from the shallow aquifer by a clay
and silt unit which ranges in thickness from 1.5 to 25 feet.
This partial confining layer is thinnest in the vicinity of MW-6
and MW-7 and thickens to the south and west. The lithology of
the deep aquifer is similar to that of the shallow aquifer,
though clay-rich layers are more common. Both the clay aquitard
and the deep aquifer are thought to be units in the Black Creek
Formation.
The gradient of the potentiometric surface in the deep aquifer
is 0.0003 ft/ft toward the south based on water level data
gathered from the four wells installed by IT Corporation.
5.2 Site Contamination
In 1989, a remedial investigation (RI) involving sampling of the
soil, surface waters, sediments, ground water, and air was
conducted at the SCRDI site to define the characteristics and
extent of contamination at the site. Comparison of the detected
levels of specific compounds to developed target cleanup
criteria is presented in Section 4.0.
5.2.1 Ground Water
5.2.1.1 Surficial Aquifer
Nineteen monitoring wells were installed in the surficial
aquifer to define the extent and characteristics of ground water
contamination. The analytical results defined a contaminant
plume approximately 1000 feet wide extending approximately 2200
-6-
-------
feet southeast of the site (see Figure 3). The depth of the
surficial aquifer is approximately 40 feet. Based on a medium
sand porosity of 0.4, the estimated volume of the plume is
263,296,000 gallons. The primary components of the
contamination are volatile and semi-volatile organic compounds.
The detected volatile and semi-volatile compounds, highest
concentrations detected and frequency of detected are summarized
in Table 1. Trace levels of semi-volatile compounds were
detected in three wells. Detected metals, highest concentration
and frequency of detection are summarized in Table 2.
Additional work, including further groundwater investigation,
will be required for the development of the Remedial Design.
5.2.1.2 Deep Aquifer
Four monitoring wells were installed in the upper portion of the
deep aquifer regionally downgradient of the site. These wells
were completed below a clay aquitard found to be continuous over
the area encompassed by well installation. Analytical results
for samples of these four lower aquifer wells showed no
contamination, indicating the deep aquifer has not been impacted
by contamination detected in the surficial aquifer.
5.2.2 Soils
The RI investigated surface and subsurface soils as potential
source areas contributing contaminants to the surficial
aquifer. Dry lagoon sediments identified in the RI are included
as soils for this and subsequent evaluations. Wet lagoon
sediments are addressed in Section 3.2.3.1.
5.2.2.1 Surface Soils
Forty-two surface soil samples were taken on and off the site in
areas of known or suspected contamination. Sampling locations
and the areas of significant organic compound content are shown
on Figure 4. The areas associated with volatile and
semi-volatile detection are approximately the same. Tables 3
and 4 summarize the detected compounds, frequency of detection
for volatile compounds and semi-volatile compounds respectively.
Two general areas of surface soil contamination were
identified. The most significant area of surface soil
contamination is found on the southwestern edge of the SCRDI
Site and encompasses approximately 350 feet X 200 feet (70,000
sq ft) .
A second area of surface soil contamination was identified in
the central portion of the SCRDI property (the dry lagoon area)
at lower concentrations than those seen at the southwestern edge
of the property. This second area encompasses approximately 100
feet X 100 feet (10,000 sq ft).
-7-
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2000 -
1600
12OO -
I
en
I
\
400
UMNO
BOO
%
tunoN ooMTnun I nw
^
120O 1AOO 2OOO
SCALE. I' = 05 fl
MOTl: CONTOUR WTIRVAL - »OO fpk
240O
FTGITRE 3
2800
3200
CHEMICAL CONCENTRATION DISTRIBUTION MAP
FOR TOTAL VOA3 IN ALL UPPER AQUIFER WELLS
-------
TAHI.K I
CKOIINIlWAH.K r.MMMAItY
OKCANIC:;
COMPOUND
Mi(ill CIINI:.
PPH
IIU CCINC.
PPB
II11 ill
11)1 At ION
NO. or
MO, Of SAHPIFS
vni AMIES
Cirhon T«tr*ehlorld«
Ace too*
Chloroform
Bertfcn*
1.1.1-lrlcMottMtliMW
H«thyl«n« Chloride
Cirbon Dliulfld*
1(1-Dlehloro«tliMM
1,1-Olchlorotlhtn*
1,2-OlchlorepropwM
1.1.2-TrlehloroathwM
lrlchlor*lh«n«
1.1.?.2-t«tr«chloro«thww
Ethylb«nitn«
1,2-Dlchloroothww
loluen*
ChlorobcniMW
lelr«chtor«lh«n«
1.2-DtcMoro«lhen«
Tolcl Kyl*n«t
StHI-VOlATIlES
200
1(101)0
?OI)0
110
260
35
A
2000
1200
21
H-NltrotodlptienylMlne
1.?-Dlchlorol*men«
280
911
900
16
Aft
AflOO
5 (SO
MO
2
NO
Nil
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
HO
Nl)
NO
MB
?A
AB
7A
I IB
AA
1A
TC
fa
AA
7/21
7A
7A
2A
?A
AA
AA
2A
2A
2A
2A
2A
111
2A
2A
r/t*
3/21
1/21
3/21
A/21
A/21
2/21
3/21
1/21
2/21
1/21
7/21
5/21
2/21
1/21
-------
TAIII.K 7
(IKOIINMWATI It SIIMMAKY
Ml! I A I.S
eoMpmwo
o
I
Alunlntn
Iron
Mlcktl
POtMtlU*
SodliH
••Hi*
MryltlM
Cobalt
CopfMf
V*n»dlui
Zinc
Calclui
Arsenic
Mercury
HIGH CONG.
rru
110
1S6
1V6
1.04
0 \f*>
7.41
17.5
1.27
0.0 AA
0.0(7
0.115
0.411
O.B11
0.551
84.5
0.257
0.004
0.001
0.0009
inu roMc .
ppn
NO
O.MA
0. (1ft
0.0 II
NO
Hl>
Nl>
0.01
HO
NO
Ml)
Nil
NO
Nil
0.009
1.B1
NO
NO
NO
NO
111 nil
inrAMim
2B
?A
?A
/A
?B
2A
2A
28
28
7C
^8
1IIB
2B
28
28
11A
28
7C
7C
28
NO. Of OfHC
.HQt-Pf-**."
22/21
21/21
21/21
21/21
21/21
16/21
22/21
21/21
9/21
4/21
10/21
9/21
17/21
9/21
21/21
21/21
11/21
1/21
2/21
6/21
-------
Low levels of pesticides/PCBs were also detected in the area of
BS-4 and SS-5. Compounds detected, the location of the highest
concentration detected and frequency of detection are summarized
in Table 5.
A summary of metals detected, the location of the highest
concentration detected, and frequency of detection is provided
in Table 6. Two samples out of thirty-four (SS-4 and SS-5) had
concentrations of mercury above the background range. The
levels detected and the localized area indicate that metals in
the surface soil are not of primary concern.
5.2.2.2 Subsurface Soils
Twenty-nine soil borings were taken on and off the site.
Samples were taken at 3 to 7 and 7 to 11 foot intervals at each
location. One additional sample at 11 to 15 feet was taken at
B9 . Figure 5 shows the sampling locations and areas of
significant volatile compound content. The volatile compounds
detected, the location of the highest concentration depth, and
frequency of detection are summarized in Table 7. Elevated
levels of volatile compounds are limited to the upper 7 feet of
the unconsolidatec zone. The areas of detected elevated levels
are limited to the proximity of B8 and B9 (approximately 300
feet ENE of B4/B5). This encompasses an area of approximately
400 feet X 250 feet (112,500 sq ft) that essentially overlaps
-that area identified with elevated volatile concentrations in
surface soils. Concentrations generally decreased with depth.
Semi-volatile compounds were also detected in the same limited
areas of B4/B5 and B8/B9. The highest concentrations were
primarily limited to the upper 7 feet of the unconsolidated zone
with concentrations decreasing significantly with depth.
Semi-volatile compounds detected, the location of the highest
concentration and depth, second highest location and depth, and
frequency of detection are summarized in Table 8.
Low levels of pesticides/PCBs were detected in the subsurface
soils in the B5, B8/B9 area, limited to the upper 7 ft of the
unconsolidated zone. Table 9 summarizes the compounds detected,
the location of the highest concentration detected and frequency
of detection.
A summary of metals detected, the location of the highest
concentration detected and frequency of detection is provided in
Table 10. One boring out of the twenty-nine taken (B13) has a
concentration of selenium above the background range. The
levels detected and the localized area indicate that metals in
the surface soil are not of concern.
-11-
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A si ir
to
I
wmrr crwrotM/wmw>u
3700
CHEMICAL CONCENTRATION DISTRIBUTION MAP
FOR TOTAL VOA/IN SURFACE SOIL SAMPLES
*
EXCLUDES ACETONE AND METHYLENE CHLORIDE
-------
TAIM.I: i
Cr. SOU. SUMMARY
VOI.ATII.I.S
COMPOUND
HIGH COMC.
PPB
ing niNC.
PPB
lllr.H
HO. or DEIECIinNS/
Acetone
CMorofor*
1.1(1,-1rlchloro«th*n«
Hethylcrw Chloride
C.rbon Of (til f Id*
1.1-DlchloroethMM
2-ButMwn*
IrlcMoroathciM
1.1.2,2-TatrachloroathMM
Ethylbeni*n«
t-Melhyl-2-P*nt*rvM*
lolucn*
Chlorobenterw
Ttlrachloro«lh«n«
1.?-OUMoro«th«n»
Iol*l Kylerwt
Styrcn*
Vinyl Chlorld*
1,1-Dlchloro«then«
•tnitn*
l,2-Dlchloro*lh«n«
lo^ino
it.ooo
t./oo
I
J90
100,000
710
29.000
lA.non
56,000
o
5.200
A
240
5VO
A
NO
HO
HO
HO
NO
Nil
Nil
HO
HO
HO
HO
HO
HO
HO
HO
HO
NO-
HO
HO
NO
sst
SSS
SSS
. nis2
sstt
sss
SSI
sss
sst
sss
SSI
sst
sst
sst
SSI
sst
SS1B
01 St
01 Si
01 S2
01 SI
t2/t2
S/t2
*/«
tl/t2
l/<2
2/t2
3/42
a/42
1/42
3/t2
1/42
14/42
1/t2
fl/42
2/42
t/42
1M2
1/42
2/42
2/42
1/42
-------
TAW.K /i
SIIKKACK SOU. SUMMARY
SI.MI-VOl.ATI I.I S
.p-
I
n I nil CIINC.
pp»
Bentolc Acid
Dl-n butyl[>hth*Ut«
2 -H« thy I phenol
2-Chlorophtnol
2.4.5-trlcMoroph«nol
••niyl Alcohol
4 -Methyl fh«nel
Phenol
Bls(2-Ethylhuyl)
Phth*l*t«
Ol-n-octylptilti»l»t«
H*K«chlorob«nt*f>«
2,4-OlcliteropliMwl
Dl«lhylph(«tal«
M-Ml lrosodlplitnylM»ln«
KM mur.
PPB
l.BOO
2.200
1.200
58,000
200.000
810
t 10,000
14.000
210.000
7.600
44.000
7.200
450
29.000
1.500
50
NO
NO
Ml)
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
II 11.11
KHMjOtj
ssia
SSt
SS4
SS4
SS4
SS4
SSt
SS4
. sss
SS5
SS4
SS4
SS4
SS4
fS4
C$21
NO. or mil Minus/
a/42
1/42
1/42
1/42
1/42
1/42
J1/42
41/42
5/42
1/42
1/42
1/42
1/42
1/42
-------
TAIU.I. ')
CI'. !;tlll. SIIMMAUY
ri-.sTicim.s/iv.ii1:;
COMPniND
t.t'-DOD
t.4*-DDI
Melhtmychlor
OUIdrln
fndo*utfin II
AroeMor 1242
ImlosuKan Sulf»t«
HI nil rniir. inu rime.
PPB rr?_.
Itt Nil
46 Nl>
??n . NII
?/IMI Mil
*)? Nl)
?6 Nil
WHO NII
AIIQ NII
Hir.H
|(K Al ION
SSS
SSIV
SSt
sst
SS/0
SS/0
sss
nisi
NO. OF DftlCTIONS,
NO, Of SOHPIfS
V*2
-------
COMPOUND
Alunlnu*
Iron
Magncslui
Manganese
Nickel
Potasilu*
S i I ver
Sodlu*
Antimony
Barium
BeryllltM
Chronltm
> upper
Vsnadlui
?lnc
CalcltM
le*d
Arsenic
Selenium
.Mercury
HIGH CONC.
PPM
13.500
39.000
813
1.240
34
2.690
5
346
6
190
1.1
4
64
9
205
64
738
94.800
158
8.2
3.6
6.56
0.9
IOU CONC.
PPM __
1170
1310
16
2.5
NO
NO
NO
NO
NO
IB
NO
NO
2
HO
NO
4
3
86
7
NO
*>
NO
NO
HM.H
lOCMJON
ssin
SSH
SS4
SS21*
SS5
SS4
SSIfl
SS5
ssin
SSI
SS18
SS5
SS4
SS5
SS5
SS11
SS5
SS24
SS5
SS5
SSZO
SS5
ssi7
MI.IAI.:
NO. of ntircnoHS
NO. or incAitnNS
34/14
34/14
34/U
34/14
11/14
B/34
5/14
21/34
2/14
34/34
3?/34
5/34
34/34
16/34
32/34
34/34
32/34
34/34
34/34
IS/34
3/34
29/34
7/34
1
BIANK
CDNIAMINAIinN
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
no
NO
NO
NO
NO
NO
ciwrrNii
RANGE PI'H
7000 100,000*
ion inn^ino*
50 SO, Olio"
? 7.000"
5/00"
50 37 000*
.01 Sfc
500 50,000*
-------
2OOO
1600
1300
800
400
• -\
\V'^.fV^!
400
nno
\
IFOFNO
'*.
• it tan
vmtrnm
Propwly
.1 I I I.
.1 L
MM
SCAI F: 1- «. 4Ti R
Morr.- ctMvmiin ttmnfM -
2000
700000 ppb
- 400000 ppb
.1 I
2400
FinimR 5
2SOO
-1200
CHEMICAL CONCENTRATION DISTRIBUTION MAP
FOR TOTAL VOA** IN SOIL BORINOS
*rxciuots ACETOME AND MCTIIYLCNC
-------
00
I
TAHI.K /
SOU. HOKINC SIKIMAKY
VOI.ATH.I.S
rnMoniun
i.i mi in JPIIP
Cnrhon let rachlorlde
Acetone
Chloroform
Brnrene
1.1.1-lrlchloroethane
Methylene Chloride
Carbon Oisulflde
1 , 1 - D Ichl oroethane
1,1-Olchloroelhene
2-8utanone
HIGH COHC.
PP8
4.100*
160.000*
160
7
f
6.800*
39.000*
2
69
44
89.000*
•V
1,1.2-Tr Ichloroethana I
trlchloroethene 25,000
1.1.2,2-1etrachloro«than« 2.300.000
Ethylbenten* 16,000
*-Hethyl-2-P«ntarton« 340
Toluene 340,000
Chlorobentent 23,000*
Tetrachlorethene 95,000
1,2-Otchloroethylene 40
Total Xylenet 62.000
»
•Duplicate It
significantly
AVF. AC80SS HIGH
HIGH POJIIHG (01
2.050
92.000
81.5
2.3
3.400
22.750
23
27.7
51,500
2V
.3
12.500
1.260.000
9,000
186
174,800
11.500
47.500
17.3
31.000
lower. Higher
MICH
sirimn im."
rAiinti nrPiM n rniir.^rrii
85
B5
m
B9
85
85
811
89
89
85
89
85
85
85
84
85
85
85
89
85
values
3-7
17
1 V
Ml
3- 7
3-7
7-11
7-11
11-15
37
711
3-7
3-7
7 11
7-11
37
37
3-7
7-11
17
used for
0
5400
si
1
^ "Yfl
tf»
140
?
3
4
1400
0
2?0
1100
610
18
1000
3
940
0
3600
this simMiy.
SFCnmi HM.H
IOTA) ION
N/A
9f
R9
nn
H9
fl r
B9
BIS
BM
H11
84
N/A
89
89
89
89
89
88
88
N/A
89
sfrnMn HM.H NO. OF DFIFCTIONS/
29
N/A
3-7
7 11
7-11
7-11
7-11
7 11
3-7
M/A
7 11
37
J 7
11-15
7 11
37
3-7
N/A
7-11
?9/?9
*/?9
Z9//9
1/29
3/29
9/29
5/29
29/29
2/29
5/29
1/29
11/29
59 ..pi.,
-------
TAIll.i: H
Illlll. IIOK INC UIMMAKY
SI.MI-VOI.AI II.I.S
VO
I
COMPOUHQ
Bentolc Acid
Henachloroeth*ne
Dl-H Butylphthil«t«
N-MI troiodlphcnylMlrw
2.4.6-lrlcMoroph«f»l
Naphthalen*
2-Methyl phenol
2-CMorophenol
2.4.5-lrlehlorophenol
Nltrobenter*
BentyI Alcohol
4-HMhylphenol
Phenol
Blt(2-Ethylhexyt)
Phthilate
Ol-M-Octyl Phthalate
MenBchlorobentene
2.4'Olchlorophenol
MICH CONC.
PPI
110.000
1200
250
620
280
3900
120,000
2,000.000
200
11.000
310.000
3,600
6,300.000
2.400
1.700
190
130.000
AVt ACBOSS HK'H
HIGH BOHING LQCMJOM
54,111 .
600
125
410
UO
1.950
65.500
1,011.500
100
5,685
1S2.000
1.800
3.375.000
1.BOO
B50
61.1
65.000
89
BS
nn
BS
BS
85
BS
BS
BS
BS
B5
•5
BS
88
B8
R9
85
HIGH SftOWO HIGH
•tmiu ri rnur PPfl
OfP'H_LL __L""'-:_1-—
1 7 5.400
17 0
J I "
17 9?
J r TI
j . 7 760
\ I 0
J • 1 "
\ T 0
J 1 "
• . f.\
1 ' 6J
j j 290
• t 0
5-7 u
7-11 °
5.7 2iO.OOO
17 W»
5-7 '.«no
V7 1.WO
17 *™
7-11 ' °
17 0
V 1 "
S(COMO HIGH
101 AIION
87
M/A
81
B?7
N/A
N/A
' 84
812
N/A
M/A
B9
84
89
BS
BS
N/A
N/A
srcmm HIGH MO. or omcnoN*/
nrPlM NO. Or lOCAMONS
7 11
M/A
1-7
17
H/A
N/A
7 11
17
M/A
M/A
17
7 11
7 11
1-7
J •
17
M/A 1/29
N/A
7/29
1/29
1/19
11/29
1/29
1/29
2/29
5/29
1/29
1/29
2/29
1/29
7/29
29/29
1/29
1/29
-------
5.2.3 Other Media
5.2.3.1 On-site Surface Water and Surface Water Sediment
The wet lagoon water and sediment samples contained trace
amounts of volatile and semi-volatile constituents. Sediment
metals concentrations were within background ranges with the
exception of calcium. Summaries for compounds detected and
frequencies are provided in Tables 11 & 12.
5.2.3.2 Off-Site Surface Water and Surface Water Sediment
Samples of off-site surface water and surface water sediment
indicated no site related, contamination. One sample (RS2)
showed an elevated level of the naturally occurring compound
benzoic acid.
5.2.3.3 Ambient Air
Ambient air samples were collected on the SCRDI property.
Toluene was detected in two of three bag samples at 22 and 27
ppb. No other constituents were detected. Air contamination is
not considered to be significant at the site.
5.3 Risk Assessment Summary
A baseline risk assessment was performed as part of the Remedial
Investigation to evaluate the potential for off-site migration
of constituents from the site and the impacts on public health
and/or the environment. The baseline risk is associated with
the No-Action Alternative.
The extent of constituents in environmental media at the SCRDI
site was shown to be limited to the on-site soils and shallow
ground water aquifer underlying the site. Elevated levels of
site related constituents were not found in off-site soil
samples, sediment or water samples from drainage ditches, the
deep ground water aquifer, or in surface water in local creeks.
The primary potential route of off-site migration was shown to
be via the shallow ground water aquifer. This aquifer may
recharge Myers creek, 3/200 feet northeast of the site
boundary. However, site-related constituents have not been
detected in Myers Creek.
Direct consumption of ground water from the surficial aquifer
within the contaminant plume would present unacceptable levels
of exposure. A trespasser scenario indicated that the presence
of site-related constituents in the soils do not present a
significant risk to the health of trespassers on the site.
-20-
-------
TAI'.l.r. '»
sun, I'.OKINO SUMMAKV
MKTAI.S
HACKr-ROntm
CONfTNIRATION
NO. Or LOCATIONS
ABOVE
COMPOUND
Aluminum
Iron
Magnesium
Mnngnnese
Nickel
Potasslun
, Silver
^j Sodlun
*"" Barlun
1 Berylllun
Cadmlun
Chromium
Cobalt
Copper
Vanadium
- 7lnc
Calcium
Lead
Arsenic
Thallium
Selenium
Mercury
HIGH CONC.
PPB _
22,100
22.700
otx
O ID
211
€. 1 •
B
663
2.1
800
103
1
07
• w
74
C'
13
30
42
34
3,630
?B
CO
0.4
04
• ^
9.7
0.37
Hir.H
LOCATIONS
fl?5
B7
B75
B2
BR
BR
B14
B2R
B25
B25
B26
B25
B25
B7
B7
B8
B15
B13
B4
B23
B13
B5
NO. or oriEciioN
un nr IDC AT IONS
Nil. Ill l« "• '_i". X—
•jn i 70
fVI /v_
* jn/yo
SVf Sv
JQ i ;>o
e v/ f v
?9/?9
10/?9
10/?9
X/po
31 fr
26/?9
29/29
5X/7O
r ) f •.'
2/29
29/29
8/29
29/29
29/29
29/29
29/29
29/29
1/29
1 /7O
!/<"'
5/29
13/29
/
PMJf.E PPH
?onn-ioo,onon
imi-ioo,onnn
r,o 50.000"
n
? ?.ooo
A
s mn
•,n ^ 7,000"
o.oi-5b
500 50.000n
in 1500°
<1-7"
<0.2-1b
n
1-1000
H
1 1000
0.3-70"
<1-7008
-------
TAItl.l. II)
SOU. HOKINC SIIMMAUY
I'KST 1C IlltS AHII I'Cll'S
to
ro
COMPOUND
I Inctane
Aroelor 1242
MMhoiycMor
1 ovnpKvn^
Hrpt»cMor
Eldrln Ketone
MICH CONC.
PPB
12
510
160
470
8A
47
AVE ACROSS
NJCMJORINQ
A
170
BO
2J5
4)
2J.5
(iir.H
I'KAIION
an
R9
p
BS
B5
BS
II I r.M
OFPMIJLl
1-7
5- 7
» 7
\- 7
17
57
5f riiwn
CONC .
n
?Af*
n
0
it
n
,H SI (OHO HK.II SirnNO HIGH
_cf)Nl^-p.!!!L J.??1'*!!0*— 9f.yN
M/A
nn
N/A
37
N/A
N/A
N/A
N/A
NO. Of OE1FCIIONS/
NO. Of tOTATIONS,
2/29
1/29
1/29
1/29
1/29
-------
TAlll.K I I
Wl-.r I.ACOON Sl.lllMI.NT SUMMARY
OKCAMICS
VOIAMtfS
CnMPOJINO
Methylen* Chlorld*
Acetone
Carbon Dltutflde
Toluene
Hir.H fllMC.
. PI'B
JS
un
to
wo. of
ni ur.iioNS/
Ilil AIIIIHS
SEHI-VOIAIIIES
COMPOUHO
HIHH CO«C.
COMC. rrn
HD. or
ntn CIIONS
ini «i IONS
phthsltt*
Phenol
Ol-n-butylph»l«te
1700
nou
IBO
1/1
PISIICIOfS/PCM
COHPOHHO
HIGH rnwr.
MO. OF
no i r.i IONS
KM A i IONS
wo
NO
-------
TAW.K 17
wr.T I.ACOON SI-.IHMKNT SIIMNAKY
MKTAI.S
Hir.H roue.
i
KJ
cnNpnwo
Alimlran
Antimony
Arttnlc
••rlin
•erylllun
Cilclim
Chronlu*
Copper
Iron
l«»d
Mercury
Nlck«l
Sedlua
line
Cytnlrf*
u.ym
6
1.6
o.n
4*l.ooo
11
7,710
19
10G
0.6?
11
29
32
11.2
NO. 111 or nri KINS/
HO. (If SAHJ'ltS
5/1
I/I
1/1
VI
3/1
\n
.1/1
j/i
3/1
1/1
1/1
1/1
e/i
1/1
1/1
1/1
1/1
1/1
-------
The predicted constituent concentrations in Myers Creek that
could result from direct undiluted discharge of the plume into
the creek would not .have a significant impact upon the
indigenous aquatic populations. The predicted chemical
concentrations in Myers Creek are over three orders of magnitude
lower than the maximum acceptable toxicant concentration (MATCs)
for the most sensitive species which may be found in Myers
Creek.
The effects or potential for bioconcentrations or
bioaccumulation were determined to be negligible at the site.
6.0 Clean-up Criteria (ARARs)
6.1 Chemical Specific ARARs
6.1.1 Ground water
Ground water at the Bluff Road Site is designated as Class GB in
accordance with the South Carolina water classification system.
The GB designation is used to classify water quality suitable as
a potential drinking water supply. Therefore, Federal and State
regulations governing the quality and usage of drinking water is
applicable.
The Safe Drinking Water Act and the State Primary Water
Regulations establish Maximum Contaminant Levels (MCLs) and non-
zero maximum contaminant level goals (MCLGs) for numerous
organic and inorganic constituents. The Cleanup Criteria shown
in Table 13 were established based on MCLs and proposed MCLs.
Where MCLs were not available, risk based numbers were
calculated as indicated by the appropriate table footnotes.
6.1.2 Soils
Although there were no chemical specific ARARs identified for
site soils, the potential for contaminants leaching from the
soils as a continuing source that could further degrade ground
water quality was considered. Therefore, a soil leachability
model was used to calculate cleanup criteria as shown in Tables
14 & 15. Where the model calculated soil cleanup criteria lower
than the ground water MCL for a specific constituent, the MCL
was used as the soil concentration. The model and appropriate
calculations are provided in Appendix A of the final draft
Feasibility Study Report.
6.2 Location Specific ARARs
Since the Bluff Road Site may affect Myers Creek through
discharge from the shallow aquifer, the Fish and Wildlife
Coordination Act would be applicable. Portions of the site and
surrounding areas have been designated as wetlands, therefore,
the following ARARs apply:
-25-
-------
TABLE 13
GROTNDWATER CLEANUP CRITERIA
VOLATILES
COMPOUND
TARGET CLEANUP
LEVELS (PPM)
NO. OF LOCATIONS
EXCEEDING TCL/
NO. OF SAMPLES
Carbon Tetrachlcride
Acetone
Chloroform
Benzene
1,1,1-Trichloroethane
Methylene Chloride
1, l-Dichloroethar,e
1,1-Dichloroether.e
1, 2-Dichlorcpropane
2-Butanor,e
1,1,2-Trichlcroethane
Trichlcrethene
1,1,2,2-Tetrachloroethane
Ethylbenzene
1, 2-Dichloroethane
4-Methyi-2-Fentaricne
Toluene
Chlorobenzene
Tetrachlcrethene
1, 2-Dichlcroether,e
Total Xylenes
2-Chlcrcphencl
5.00E-03"
1.10E+OOd
2.09E-02C
5.00E-033
2.00E-01a
1.70E-02C
5.00E-033
7.00E-02a
5.00E-03J
5.50E-01d
,2.20E-03C
5.00E-03a
6.00E-04C
7.00E-01a
5.00E-03a
5.50E-01C
2.00E+OOa
l.OOE-013
5.00E-03a
7.00E-02a
5.50E-02
6/23
1/23
5/23
2/23
1/23
2/23
5/2:
3/23
1/23
1/23
2/23
5/23
6/23
0/23
3/22
0/23
0/23
0/23
5/22
3/22
C/22
0/22
"i. * c
Iron
Manganese
Barium
Cadmium
Chromium
Copper
Zinc
Lead
Arsenic
Selenium
Mercury
3.00E-016
5.00E-026
1.00E*OOa
5.00E-03a
5.00E-023
l.OOE^OO®
5.00E+OOe
5.00E-03a
5.00E-02a
l.OOE-023
2.00E-033
aSWDA, MCLS, proposed MCLS,. non-zero MCLGs.
^Derived from CPF and exposure model.
"Derived from RFD and exposure model.
e£outh Carolina MCL's for Class GB groundwater,
16/22
IS/22
2/23
2/23
3/23
0/23
0/23
3/23
0/23
0/23
0/23
- 26 -
-------
TABLE U
SOIL CLEANUP CRITERIA
COMPOUND
Carbon Tetrachloride
Acetone
Chloroform
1,1,1,-Trichloroethane
Kethylene Chloride
1,1-Dichicroethane
2-Eutancne (KEY.)
Trichlorcethene
1,1,2, 2-Tetrachlcrcethar.e
I ~ r.y 1 b e r. ^ ene
4-Xethyl-2-?entancne
Tcluer.e
Cr.lcrcber.zere
Tetracr.lcroethene
1,2-Dichlcroethene
Tct=l Xyienes
Vir.vl Chlcride
1, l-Dichlcroether.e
Eer.zene
"1 p—r.i f-v i n^op*"'".?***£•
± I f. ^^tv*._W^^Cw**w«.C
2-Chlcrcrher.cl
Fhercl
TARGET CLEANUP
LEVEL-PPM
5.30E-02
1.10E*OOa
2.10E-02
1.03E+00
1.70E-02a
6.00E-03
5.50E-C2a
1.80E-02
1.00E-C3
2.23E-01
5.50E-01£
1..74Z-01
S.56Z-01
5.30E-C2
1.20E-01
€.951-^01
3.0CZ-C3
1.30Z-02
1.2CZ-02
5.00Z-03
5.5C-Z-C1
3.951-00
1.00Z-C3
NO. OF LOCATIONS > TCL
NO. OF SAMPLE LOCATION;
1/71
14/71
5/71
2/71
20/71
3/71
3/71
6/71
9/71
0/71
0/71
2/71
2/71
9/71
0/71
0/71
1/71
3/71
1/71
2/71
3/71
4/71
1/71
aC-rcur.= Water Tarcet Cleanup Level
- 27 -
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TABLE 15
WIT LAGOON SEDIMENT CLEANUP CRITERIA
VOLATILES
TARGET CLEANUP LOCATIONS
COMPOUND LEVEL PPM > TCL
Methylene Chloride 1.70E-02 2
Acetone 1.10E+00 0
Toluene 1.74E+01 0
SEMI-VCLATILZS
TARGET CLEANUP LOCATIONS
COMPOUND LEVEL-PPM > TCL
Phenol 3.95E-rOO 0
- 26 -
-------
TAIU.K'~lf.
ACTION-SIM.CI KIC AKARs KOK SOU. AND CKOUNMWATI-'.K TKKATMKNT
ni.HIT KOAD - ;;
ARABS
STATUS
SYNOPSIS
ACTION TO BE TArtH TO ATTAIN ARABS
A. COMMON TO All ALTERNATIVES:
OSHA-f.eneral Industry Standards
29CFR 1910)
OSHA-Safety and Health Standards
(29CFR 19?6)
Applicable These regulations specify the fl-hour
time-wriqhtrd average concentration (or worker
e«posiire to various orqnnic con^xiuntk. Training
requirements for workers nt ha/nrdous waste
operations nre specified in ?9 r.fB 1910.1?f).
AnpUcnHle This regulation specifies the type of snfety
equipment and procrMliires to l>e followed diirinr)
site r erne*) i n t i on.
Proper respiratory equipment wilt be worn If it
is not possible to maintain the work atmosphere
helow these concentrations.
Alt appropriate aafety equipment will be on-site
and appropriate procedures will be. followed
during treatment activities.
OSHA-Record keeping, reporting and Applicable
Related Regulations, (29 CFR 1904)
RCRA-Standards for Owners/Operator* Relevant t
of Permitted Hazardous Waste Appropriate
facilities (40 CfR 264.10-364.18)
RCRA-Preparedness and Prevention Relevant t
«0 CfR 264.30-244.31) Appropriate
This regulation outlines the record keeping and
reporting requirements for an employer under
OSHA.
General facility requirements outline
waste analysis, security measures, Inspections
and training requirements.
This regulation outlines the requirements for
safety equipment and spill control.
These regulations apply to the conf>any(8) <
contracted to Install, operate, and maintain the
treatment alte.
Facility will be designed, constructed, and
operated In accordant* with thla requirement.
All workers will be properly trained.
Safety and communication equipment will be
installed at the site, local authorities will
be familiarized with the tlte.
RCRA-Contlngeney Pl«n and Emergency Relevant &
Procedures (40 CFR 264.50-264.56). Appropriate
RCRA-Closure and Post-Closure Relevant t
('.0 CfB 264.110-264.120) Appropriate
This regulation outlines the requirements for
emergency procedures to lie used following
enplosions, fires, etc.
The regulations fMnils specific requirements
for closure nrxl post-closure of hn/nrdous
wnste fnr.i I i t ies.
Plans will be developed and Implemented during
remedial design. Copies of the plan will be
kept on-slte.
Since groundwater will be cleaned to drinking
water standards, post-closure standards will be
met.
Waste Transportation;
DOT Rules for Transportation of
Hazardous Materials (49 CFR Parts
T07, Ul.1-172.55fl)
Applicable This regulation outlines procedures for the
pnrkaging, Inliellng, mnnifesting, and
trnnsfmrt ing of hnrnidmis moterlnls.
this regulation will be applicable to any
rompnny contracted to transport hazardous
mnfrlal from the site.
-------
TAIU.K lf> (CONTINIIKD)
ARABS
STATUS
SYWMPSIS
ACTION TO BE TAKFH TO ATTAIN ABABS
OJ
O
Thermal Treatment;
40 CFR 60.52: MSPS
40 CFR 264: Subpart 0
40 CFR 264.341-345
Applicable Provider pnrtirulnte emission limit-; (or
incincrntors.
Applicable Provides performnnce stmidnrds for hnrnrdl I«!S to mnjor statlonnry sources stirh as
trfBtmont units that hnve the potenlinl to emit
significant amounts of pollutants such as NO^
SO.. CO. lend, mercury and partlculates (more
than 250 tons/year). Regulations under CAA do
not specifically regulate emissions from
hniardous unste Incinerators, but It is likely
that Prevention of Significant Deterioration
(PSD) provisions would npply *° "n on-site
treatment fnrility.
If a treatment or stornqe unit Is to be
constructed for on-slle remedial action, there
should l>e a clenr Intent to dismnntle, remove, or
close the unit after the CF.RCI A notion is
ron\pleted.
Partlculate emission limits should be specified
for compllarKe.
Performance standards should be specified for
conpl ianre.
Proper designs will be Implemented to meet these
re<^ui rements.
These requirements will be Included to meet
these regulations.
These requirements will be. Included to meet
these regulations.
The treatment system Mill be designed to meet
these emission limits. PSO procedure was not.
Included In this phase of FS.
Only properly permitted facilities will be
considered for disposal of hazardous materials.
-------
IAIII.I. Id ((ONI I Mill II)
ARAKS
SMIIIS
W**t« transportation
Standard! Applicable to transporter* of AppHr*l>le
Naiardoua Uatle-RCRA faction JOOJ.
(40 CM 262 and 26J. 40 CM 170
to tTV)
Rf IMIIHIMINI
MtaMishr* the retpnnsltii I i ty of off tile
tianspnrtert of harardous waste In the hand! ing
transportation, and Management of the watte.
Reipjire* • tvmifest, terorrlkeeping, ami
immediate action In the event of • di
of hciardmit unite.
ip
lhl« regulation will ba appllcabla to any
cnafiany contracted to traiupnrl haiardom
BMterlal fro* tha alta.
•CM land Dltpotal •••trlet Ion* Appl Icnhlo
((0 Cft ?M. Suhpart P)
EPA Ad*lnUtarad ••rail *ro«raai: Appllcahla
Ifia Naiartfeus Waal* Parailt frogra*
MCM faction 1005. 40 CM 2/0. 124
Since Mnve*i«r B. 19B0, anvment of encavated
•alerialt to nru location wnl plarenrnt in or
on land Irlggrri land dlipntil reililetlont.
Covert the basic permitting, application,
•mil tor Ing end irportlno r trfjt f »**r>t t for
off-all* haianliMil uaite •*rt*ge«irnl facllltlei.
Any regulated contaminant* foovf In aolla
ancavaled will ba properly dUpoaed or Irtaled
aa required by tha regulation*.
Any off-alia facility accepting haiardom uaile
from the alta auet ba properly pareiltled.
laplcewntatlon of the aliarnatlva will Include
conaldaratlon of requlr«*»rnt«.
g. SOU TMAINIIIf:
40 era- ?o2t
Appllcabla Establltho alandarda for generator* of haiardoua thla regulation will be appllcabla upon
waslea Including watte drlcrainalion, eMnlfetta. excavation and on-all* atorage of alta watte*.
ami pre-tran*pui t rexpitieaientt.
Clean CtOtUff;
Cenaral Standard* (40 Cft
2&4.11D
Relevant t Oneral pert01 nance ttaivUid ie<|iiires Proper dealgn corulderttIon* will be la*>lea*nled
Appropriate niitiajiiat ion of need for further maintenance and to mlnlmll* Ih* need lor fulura aailntenanta.
control; etlnimi tat ion or elimination of Occontamlnat Ion facility will be tntluled.
putt -closure esi «pe of haiardotit watte, htiardmn
totiil it oeiils, leaihale, contaminated n»«ol I. or
Ii4l*iiloiis u*slr tlrconpotllion proilurtt. Also
ret|iiiies (Iis|>osal or o>conl«mu>«t Ion of
riKHiniriil M i »i Ini rs . •i«lvolU.
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TAI'.l.r. 16 (CONTINUKD)
ARABS
STATUS
SYNOPSIS
TO RF TAKFH TO ATTAIN ARARS
TNormal Treatment:
40 rr» 60.52: HSPS
Provides pnrticulate emission limit"; for
incinerators.
Putt I dilute emission limits should be specified
for compliance.
40 CfR 264: Suhpart 0
Applicable Provider performance stnnrlnrds tor hnrnrdnm
u.iste inc inerntors.
Performance standards should he specified for
eompl iance.
40 CfR 264.341-345
Applicable • Provided p*rformnnce stnnrlard1! and rlo-;iire
roqtiirrMnrnts for tnclnrratnr <(r«;iqn niwl opcrntinn
(or Hpstructlnn on POIIf, and limits pmi«;sion«; of
HC.I , pnrt irnlate<;, anH carbon monoxide.
Proper designs will be Implemented to meet these
reqnlrrtnpntn.
40 CfR ?A4.347
Applicable Provides monitoring and inspection requirement<:
while incinerating uaste.
These requirements ulll be Included to meet'
these regulations.
OJ
K)
40 CFM ?M. 351
CAA-HAAOS (40 CM 1-99)
Applicable
Applicable
Interim RCM/CERCIA Guidance on To be
Non-Contiguous Site* and On-Slte ConslderoH
Hanaqement of Waste and Treated
Residue (USEPA Policy Statement,
March 27, 1986)
Provides requirements for disposal of Incinerated
ash, scn*+>er uaste, and scrubber sludge.
Applies to major stationary sources such as
treatment units that have the potential to emit
significant amounts of pollutants such as NO^
SO-, CO, lead, mercury and partlculetes (more
than 250 tons/year). Regulations under CAA do
not specif leal ly'regulate emissions from
hazardous waste Incinerators, hut It is likely
that Prevention of Significant Deterioration
(PSO) provisions would apply to an on-site
treatment facility.
If a treatment or storage unit Is to he
constructed for on-site remedial action, there
should he a rlenr intent to dismantle, remove, or
close the unit after the CERCI.A action is
cnmjil eteil.
These requirement* will be Included to meet
these regulations.
The treatment system will be designed to meet
these emission limits. PSO procedure was not
Included In this phase of fS.
Only properly permitted facilities will be
considered for disposal of haiardous materials.
-------
TAW.K If, (CONTIMir.D)
ARABS
STATUS
SYNOPSIS
ACTIOM TO BE TArFMTO ATTAIN ARARS
CAA-NAAQS for Partleulate Matter less Relevant t
Than 10 Microns In Diameter (40 r.fR Appropriate
Part 60, AppendIn J
This requlation specifies mnniniin nnnunl
arithmetic menn nnd mnnimnn ?4-hoe determined on
a case-hy-cnse hnsis.
U)
I
South Carolina Pollution Control Act Retrvnnt *
Appropriate
Provides r«k
-------
TAi'.i.i: ir> (CONTINHI:!))
RFOIMRFMtMI SYNOPSIS
ACTIOH TO BE WfMTOATTAIN ARARS
Air Emissions
NFSHAP (40 CFR 61)
Applicable Provides emission standards for hajardous nir
pollutants stirh nt beryllitm, mercury, vinyl
rhloricto, hrn/cnc, nrspnir, nnrt lonrt.
Profx?r deslgnu on «lr emissions controls
will be implemented to these requlntions.
NAAOS (40 CFM 50)
iml'le Provides nir qimlity stnndnrd1: for pnrt irul ntrs Snme as ilhove.
Irnd nnd oionp.
PSD «0 C« 51. 2)
Appllcnhle
South Carolina Pollution Control Act Applicable
Hew mnjor stntlonnry sources mny be snbjert to PSD procedures have not been Included In this FS
PSO review. I.e.. require best nvnilHble cnntrot but cotild be expanded to B»CI and LAER
technology (RACT), lowest arhievnble emission evaluations.
limit (LAD), anil/or emission offsets.
Provides air quality stnndnrds (or emissions
in South Carol inn
Proper designs on air emissions controls
will be Implemented to these regulations.
-------
o Clean Water Act, Section 404
o Protection of Flood Plain (40 CFR 6, Appendix A) Fish
and Wildlife Coordination Act
o General RCRA Facility Location Standards (40 CFR 264.18)
6.3 Action Specific ARARs
The action specific ARARs for this site are summarized in Table
16. The ARARs are divided into three categories:
o ARARs for actions taken in all alternatives
o ARARs for actions involving soil treatment
o ARARs for actions involving ground water treatment
The first category is requirements for safety and health,
hazardous waste facilities, and transportation. The second
category is requirements for excavation, thermal treatment, soil
vapor extraction, and clean closure of site soils. The third
category includes ARARs concerning discharge of treated ground
water and related air emissions.
6.4 Other Criteria, Advisories and Guidance
Other to-be-considered (TBC) Criteria, Advisories and Guidance
which were used in the public health evaluations and
determinations of some of the cleanup criteria are shown in
Table 17.
7.0 Documentation of Significant Changes
The preferred alternative presented in the proposed plan
identified excavation and treatment by thermal desorption of
contaminated soils at the site and extraction and treatment by
air stripping/carbon adsorption of contaminated groundwater.
The source control (soil) remedial action presented in this ROD
differs from the proposed plan in that this ROD documents
selection of soil vacuum extraction as the preferred alternative
for treating contaminated soil at the site. Soil vacuum
extraction was chosen over thermal desorption based on
preliminary pilot tests indicating the semi-volatile
contaminants can be removed using the soil vacuum extraction
technique. The pilot test also demonstrated that the clay
layers and saturated conditions will not pose the impediment
originally anticipated. The results of the pilot test give a
good indication that the cleanup criteria are achievable using
soil vacuum extraction.
-36-
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TABLE 17 OTHER FEDERAL AND STATE CRITERIA, ADVISORIES
A:::- GUIDANCE, TO-BE-CONSIDERED (TBC)
REQUIREMENTS
RATIOHALE
1. Health Advisories, EPA Office
cf Drinking Water
2. Reference Doses (R*Ds) , EPA
Office cf Research^and
Deveicpr.er.t.
3. Health Effects Assessments
4. Carcinogenic Pctency Factors,
E?A Environmental Criteria
and Assessment Office, EPA
Carcinccer. Assessment Group
5. U.S. Environmental Protection
Agency Exposure Factors
Handbook, 19 £9
6. Agency for Toxic Substances
and Disease Registry,
lexicological Profiles
7. U.S. Environmental Protection
Agency Risk Assessment Guidance
for Superfund Human Health
Manual Fart A, Interim Final,
198Sb
8. CERCLA Compliance With Other
Lavs Manual, 1988a
RI Activities identified
presence of chemicals for
which health advisories
are listed
Considered in the public
health evaluation
Considered in the public
health evaluation
Considered in the public
health evaluation
Considered in the public
health -evaluation
Considered in the public
health evaluation
Considered in the public
health evaluation
Considered in the public
health evaluation
- 35 -
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8.0 Alternative Evaluation
8.1 No Action Alternative
The no-action alternative serves as a baseline for comparison of
the overall effectiveness of each ground water remediation
alternative.
8.1.1 Technical Description
The no action alternative would not utilize any active remedial
technology for the ground water contaminant plume. The current
interaction between the ground water plume and the surrounding
environment would be allowed to continue. The site currently
has a fence around the accessible perimeter.
In addition, ground water sampling and analysis would be
conducted for the upper aquifer and lower aquifer to monitor any
migration (horizontal and vertical) of the ground water plume.
8.1.2 Short-Term Effectiveness
The only potential impacts on workers would occur during ground
water sampling events. Personnel involved with ground water
sampling at the site would be required to comply with a site
specific Health and Safety Plan to mitigate the potential
impacts from worker exposure to ground water. Installation of
shallow drinking water wells on-site would pose an immediate
threat to the user.
8.1.3 Long-Term Effectiveness
The baseline risk assessment presented in the Remedial
Investigation Report concluded that the site poses no
unacceptable levels of risk to public health or environment
associated with the migration of the ground water plume. This
is due to the fact the site is abandoned and no wells have been
installed immediately downgradient of the site in the
contaminated portion of the aquifer. For the future use
scenarios, there is a potential for unacceptable levels of
exposure.
Groundwater quality monitoring is demonstrated and reliable for
detecting the migration of the ground water plume. Potential
migration pathways would be monitored by ground water sampling
and analysis over time.
-37-
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8.1*4 Reduction of Toxicity. Mobility, or Volume
Under the no action alternative, treatment of the ground water
plume would not occur. Therefore, the toxicity, mobility, or
volume of the ground water plume contaminants would not be
reduced. The rate of dilution would be slow and the time
required to reach an acceptable concentration level of
contaminants in the ground water is unknown.
8.1.5 Implementability
The no action alternative is technically feasible and would
employ common techniques for continued monitoring of the ground
water plume. This alternative would not require any specific
permits to implement.
8.1.6 Compliance with ARARs
Chemical Specific ARARs
Implementation of the no action alternative would not achieve
compliance with the chemical specific ARARs (identified in
Section 4.0) for ground water since the chemical compounds to
remain in the ground water plume would exceed the cleanup
criteria.
Location Specific ARARs
Because the no action alternative would potentially allow the
ground water plume contaminants to migrate into the lower
aquifer and/or discharge into Myers Creek, the following
location specific ARARs would apply:
o Clean Water Act, Section 404
o Fish and Wildlife Coordination Act
It is not possible at this time to determine if the migration oJ
the ground water plume contaminants into Myers Creek would
comply with the above listed location specific ARARs.
Action Specific ARARs
The applicable requirements associated with the no action
alternative would be the regulations governing work at the site
for the ground water monitoring actions and fence maintenance.
These regulations are as follows:
-38-
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o OSHA - General Industry Standards (29 CFR 1910) which
require respiratory protection and training for
workers at the site; -
o OSHA - Safety and Health Standards (29 CFR 1926)
which dictate safety procedures for work activities;
and
o OSHA - Record keeping, Reporting and Related
Regulations (29 CFR 1904).
The ground water monitoring program and maintenance activities
to be performed at the site would be designed to comply with the
above listed action specific ARARs.
8.1.7 Overall Protection of Human Health and the Environment
The baseline risk assessment concluded that there appears to be
concentrations of certain compounds in the ground water that may
result in elevated levels of exposure if all the health
protective assumptions of the future use scenarios are realized
(i.e. future drinking water scenario). The site could pose an
exposure threat if no action is taken.
The no action alternative would not comply with the chemical
specific ARARs for groundwater. Activities under the no action
alternative (ground water sampling, etc.) would comply with the
identified action specific ARARs. It is not possible at this
time to determine if any location specific ARARs would apply to
the no action alternative because the ground water plume has not
migrated to Myers Creek.
8.1.8 Cost
The costs associated with the no action alternative were assumed
to include quarterly sampling of 16 monitoring wells (MW-1A, IB,
3A, 3B, 7A, 7B, 7C, 8B, 9B, 9C, 10B, 11A, 11B, 12B, 12C, and
13B) for metals, volatile and semi-volatile organics for a
period of thirty years. Reduction in the sampling frequency
would be evaluated based on the results of the first five year's
quarterly monitoring. In addition, there would be the cost of
fence and roadway maintenance at the site. The total 30 year
present worth cost of the no action alternative is $760,000. A
breakdown of the estimated no action alternative cost is
presented in the final draft Feasibility Study Report.
-39-
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8.2 Ground Water Extraction and Treatment by Carbon
Adsorption
8.2.1 Technical Description
This alternative consists of a combination of ground water
extraction and ground water treatment. Contaminated ground
water would be extracted from the upper aquifer by installing
recovery wells. Ground water treatment would be accomplished by
means of carbon adsorption. A pretreatment process, such as
precipitation or flocculation, may be necessary to remove metals
from the ground water prior to treatment by carbon adsorption.
The need for any such pretreatment process would be evaluated as
part of the remedial design activities.
The ground water extraction system would consist of a
combination of recovery wells located within the contaminant
plume, and at the periphery of the plume. Recovery wells would
be placed in the more highly contaminated zone of the plume to
facilitate rapid removal of organic contaminants. The periphery
wells would be used to limit expansion of the plume. Figure 6
shows potential location of the ground water extraction wells.
The actual extraction system including number, location, and
configuration of wells would be developed during the remedial
design. Pump tests and ground water modeling would be required
to adequately define the extraction system. For the purpose of
this analysis, four extraction wells and a total flow of 100 gpm
were used. The pumping rate is a conservative value based on
data from the RI. Carbon adsorption is a process by which the
organic molecules in a waste stream are selectively attracted to
the internal pores of the activated carbon granules. Adsorption
is a surface attraction phenomenon which depends on the strength
of the molecular attraction between adsorbent and adsorbent,
electrokinetic charge, pH, and surface area. The waste stream
would be usually contacted with the activated carbon by means of
flow through a series of packed bed reactors.
Once the micropore surfaces of the carbon are saturated with
organics, the carbon is "spent" and must either be replaced with
virgin carbon or removed, thermally regenerated, and replaced.
The time to reach "breakthrough" or exhaustion is the single
most critical operating parameter. Carbon longevity balanced
against influent concentrations governs operating economics.
The ground water from the extraction wells would be pumped into
a surge tank before it is fed to the carbon adsorption system.
The carbon adsorption system would consist of units which
contain granular activated carbon (GAC) and operate in a
downflow mode. The downflow fixed bed mode has been found to be
generally most cost-effective and produces the lowest effluent
concentrations relative to other carbon adsorber
configurations. The units will be connected in parallel to
provide increased hydraulic capacity.
-40-
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2000 -
180O
12OO -
•00 -
400 -
Nora: cnMnxm MranvAL - »MM fffc
320O
M., I>OCATIONS OF
OROIIND WATFIR EXTRACTION WEU.S
GRCMINO WATK.K KXTRAHTION WKI.I.
-------
In order to minimize the carbon regeneration requirements, the
carbon may be preceded by a pretreatment system (e.g.
precipitation, filtration, etc.). to reduce suspended solids and
inorganics such as iron. The carbon adsorption system evaluated
for the Bluff Road Site would include two-dual bed carbon units
with each bed containing 20,000 Ibs. of GAG each. Four units
would be needed to provide backup of other units during GAC
regeneration. Field pilot plant testing would be performed to
accurately predict performance, longevity and operating costs.
8.2.2 Short-Term Effectiveness
Carbon adsorption is a proven technology that if properly
designed and operated, will remove the semi-volatile and
volatile contaminants and not pose a human health hazard during
operation. The system would be a closed system with no air
emissions, therefore, there would be no risk through the
inhalation pathway.
The potential short-term risks to site workers, public health
and the environment are:
o Exposure to contaminated drilling fluids and soil
during the installation of the ground water
extraction wells.
o Release of contaminated water because of accidental
spillage.
To mitigate risk posed by exposure to site constituents during
well installations, workers would be required to comply with a
site specific health and safety plan (including requirements for
protective clothing). The potential environmental risk due to
accidental spillage of ground water would be mitigated by proper
process design. The treatment system design would incorporate
process controls such as level switches and extraction pump
shut-off controls.
8.2.3 Long-Term Effectiveness and Permanence
Magnitude of Residual Risk: The ground water treatment system
would be designed such that all contaminants contained in
extracted ground water would be reduced to levels at or below
cleanup criteria.
The residuals resulting from operation of the treatment system
would include filtered solids or settled solids and spent
carbon. The carbon would be either regenerated or would be
disposed by incineration or landfilling at an off-site RCRA
treatment, storage, and disposal facility. The filtered or
settled solids would be disposed in accordance with applicable
regulations depending upon the hazardous characteristics
exhibited by the solids.
-42-
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8.2.4 Reduction in Toxicitv, Mobility, or Volume
The pumping system would control the mobility of contaminants by
extracting ground water within the upper aquifer and, therefore,
stopping further migration.. The contaminated water would be
treated by the carbon adsorption unit, thereby reducing the
toxicity of the ground water.
8.2.5 Implementability
Technical Feasibility; Carbon adsorption has been used
extensively to treat contaminated ground water and has shown
success in removing organic contaminants from ground water.
Design and construction of the necessary treatment units would
not pose a problem. Some equipment manufactures offer modular
units that can be made to fit an individual application with
minor modification. Precipitation and filtration have been well
demonstrated for removal of inorganic compounds from aqueous
streams. The equipment used in these processes is proven and
reliable, thus downtime for repairs and maintenance should be
minimal.
During operation of the treatment system, the effectiveness of
the treatment process would be monitored by periodically
analyzing contaminant concentrations in the treated water prior
to discharge. Monitoring of ground water would be necessary
during the operation of the system to ensure that the periphery
of the plume is being treated.
Administrative Feasibility; The use of carbon adsorption would
require compliance with U.S. EPA, U.S. Department of
Transportation, and SCDHEC regulations regarding the transport
and disposal of hazardous materials (spent carbon, filtered and
settled solids from pretreatment system). In addition, disposal
regulations and criteria must be met for discharge of the
treated water.
Availability of Services and Materials; A range of vendors are
available to supply all necessary units of the treatment
systems. Because of the large number of equipment suppliers,
availability and scheduling considerations would not be
anticipated to pose problems.
8.2.6 Compliance with ARARs
Chemical-Specific; This alternative is designed to treat the
ground water contaminants to attain the cleanup criteria.
Chemical-specific ARARs for the Bluff Road Site were identified
and discussed in Section 4.0. Several Federal and State
regulations govern the quality, usage and discharge of ground
water. Since ground water at the site has been classified as a
drinking water source, all Federal and/or State drinking water
standards would apply.
-43-
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Location-Specific; The ground water extraction and treatment
system would be located on the Bluff Road Site which is
proximate to a wetland. Construction of this system as
conceived may impact the wetland. The extent of the impact will
be carefully considered during the remedial design. The impact
to wetlands will be minimized and where it cannot be avoided the
damage will be mitigated.
Action-Specific; This alternative would be designed to comply
with action-specific ARARs. The action-specific ARARs for
construction of the extraction and treatment systems, the
treatment and subsequent disposal of the treated ground water
and the management of treatment residuals were summarized in
Section 4.0. Many RCRA Subtitle C requirements may apply
because the site contains hazardous waste. RCRA Part 264
requirements may apply including standards for owners and
operators of permitted hazardous waste facilities, preparedness
and prevention, contingencies and emergency procedures,
recordkeeping and reporting, and ground water monitoring.
Federal OSHA worker health and safety requirements would be
applicable to the construction and operation activities.
8.2.7 Overall Protection of Human Health and the
Environment
This alternative would decrease the potential risk resulting
from direct contact and ingestion of site ground water because
the ground water would be treated to meet the clean-up
criteria. This alternative can be implemented to meet
identified ARARs.
8.2.8 Cost
The present worth cost of the Carbon Adsorption alternative,
would be approximately $16,105,000.00. This cost would include
a capital cost of $1,390,000.00, and present worth 0 & M cost of
$14,715,000. A complete cost summary is included in the final
draft Feasibility Study Report.
8.3 Ground Water Extraction and Treatment bv Air Stripping
8.3.1 Technical Description
This alternative consists of a combination of ground water
extraction and ground water treatment. Contaminated ground
water would be extracted from the upper aquifer by installing
recovery wells. Ground water treatment would be accomplished by
means of air stripping towers, followed by a granular activated
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carbon (GAC) system. The more volatile constituents in ground
water would be removed by air stripping, while semi-volatiles
would be removed by the GAC system. A pretreatment process,
such as precipitation or flocculation, may be necessary to
remove metals from the ground water prior to treatment by air
stripping and GAC. The need for any such pretreatment process
would be evaluated as part of the remedial design activities.
The ground water extraction system would consist of a
combination of recovery wells located within the contaminant
plume, and at the periphery of the plume. Recovery wells would
be placed in the more highly contaminated zone of the plume to
facilitate rapid removal of organics. The periphery wells would
be used to limit expansion of the plume.
The extraction system including number, location, and
configuration of wells would be developed during the remedial
design. Pump tests and ground water modeling would be required
for the design of the extraction system. For the purpose of
this analysis, four extraction wells and a total flow of 100 gpm
were used. The pumping rate is a conservative value based on
data from the RI.
The ground water from the extraction wells would be pumped into
a surge tank before it is fed to the air stripping system. The
air stripping system would consist of two towers arranged in
series. Both towers would have 12 feet of packing material, 30
inches in diameter and use high air-to-water ratios. The use of
two air strippers in series offers the following benefits over a
single air stripper with comparable treatment capacity:
- If one of the air strippers would require
maintenance, the other air stripper could continue
to operate;
- Treatment capacity could be increased by running the
strippers in parallel, should expansion of the
extraction system become necessary.
Prior to treatment, the extracted ground water would contain the
compounds identified in Tables 1 and 2 at the measured maximum
concentration shown in column 1. Contaminant concentrations
should steadily decrease from these levels. Actual treatment
system influent composition would be defined during remedial
design.
Air stripping can effectively remove most of these contaminants
found in ground water at the Bluff Road Site (Colder, 1986).
The exceptions would be 2-chlorophenol and phenols which would
be removed by adsorption on the GAC.
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After air stripping, the ground water would be pumped through
cartridge filters and two carbon beds, also arranged in series.
When the carbon in the first bed is spent, it would be
replaced. A valve on the adsorption system would then be
switched to reverse the order of the beds in the series. The
beds are sized so that carbon would be expected to be replaced
every 4 to 6 weeks. The system would be automated and designed
for unattended operation. The final design of the ground water
extraction system, air stripper, and GAC systems would require
additional data collection prior to design.
As a result of ground water extraction and treatment, a
discharge stream of treated ground water would be generated. As
a best engineering judgement based on available data, the
volumetric flow of the discharge stream is assumed to be 144,000
gallons per day based on 100 gpm ground water recovery system
operating 24 hours per day. More precise ground water
withdrawal and discharge values would be determined as part of
the remedial design. Further discussion of effluent discharge
alternatives is presented in Section 5.4.
8.3.2 Short-Term Effectiveness
Potential short-term risks to public health and the environment
during the implementation of this alternative include the
potential inhalation of organic vapors released from the air
stripping process. An air dispersion model was used to
calculate the ambient air quality resulting from the organic
vapor emissions from the air stripper after vapor phase carbon
adsorption treatment. The air dispersion modeling was conducted
in accordance with applicable EPA guidance documents. Based on
the results of the air dispersion model, a health evaluation was
conducted to determine the potential risk, if any, to public
health from the inhalation of organic vapors. The air
dispersion model results and associated risk health evaluation
are presented in Appendix C of the final draft Feasibility Study
Report.
The air dispersion modeling for this alternative identified the
downwind location where the maximum one-hour concentrations
would be expected and the location where the maximum annual
concentrations would be expected. The ambient air
concentrations for the chemicals of concern at these locations
determined by the air dispersion model were used to determine
the potential risk, if any, to public health from the inhalation
of organic vapors generated by the air stripping process.
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The public health evaluation identified the following potential
receptor groups which may experience maximum exposures to
airborne contaminants:
1. Remediation workers in the immediate vicinity of the air
stripper who might be exposed to short-term (one hour) peak
concentrations;
2. Remediation workers present at the site for the duration
of the remedial action (16 years) who might be exposed to
airborne contaminants; and
3. Off-site residents who might be exposed to airborne
contaminants for the duration of the remedial action (16
years).
For the first receptor group (remediation workers exposed for
one hour to peak concentrations) the maximum predicted one-hour
concentrations for each chemical of concern were compared to the
Threshold Limit Values for those chemicals. Threshold Limit
Values have been developed by the American Conference of
Governmental and Industrial Hygienists (ACGIH) and are
occupational exposure criteria that represent airborne
concentrations of substances to which nearly all workers may be
repeatedly exposed without adverse effects. The maximum
predicted one-hour concentrations are far below the threshold
limit values for occupational exposure, therefore, it is
concluded that there is no danger of acute toxicity due to
exposure to short-term emissions from the air stripper system.
For the second receptor group (remediation workers present at
the site for the duration of the remedial action), the total
cancer risk associated with exposure to maximum concentrations
of all the chemicals of concern is estimated at 5.9 x 10~9
under the conditions of this scenario presented in Appendix C of
the revised draft Feasibility Study Report. The total hazard
index for non-carcinogenic effects is 3.5 x 10 which is
below the 1.0 hazard index value which indicates a potential
hazard.
To represent the third receptor group (off-site residents who
might be exposed for the duration of the remedial action), a
child was used because of higher inhalation rate to body weight
ratio, thus resulting in a worst case exposure scenario.
Forthis receptor group, the total estimated cancer risk
associated with exposure to maximum concentrations of all the
chemicals of concern is 1.1 x 10"" . The total hazard index for
non-carcinogenic effects is 2.7 x 10 , which is far below the
1.0 hazard index value which indicates a potential hazard.
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Two other potential short-term risks to site workers and the
environment are:
o Exposure to drilling fluids and soil during the
installation of the ground water extraction wells.
o Release of contaminated water because of accidental
spillage.
To mitigate risk posed by exposure to site constituents during
well installations, workers would be required to comply with a
site specific health and safety plan (including requirements for
protective clothing). The potential environmental risk due to
accidental spillage of ground water would be mitigated by proper
process design. The treatment system design would incorporate
process controls such as level switches and extraction pump
shut-off controls.
8.3.3 Long Term Effectiveness
Magnitude of Residual Risks
This ground water alternative would be implemented until the
ground water concentrations are reduced to the cleanup
criteria. To determine the magnitude of residual risk at the
site after the ground water remedial action is complete/ the
drinking water scenario was reevaluated based on the cleanup
criteria. The results of the post remediation risk assessment
for ground water ingestion is represented in Appendix B of the
final draft Feasibility Study report.
The residuals resulting from operation of the treatment system
would include filtered solids and spent carbon. The filtered
solids and the carbon would be either regenerated at a permitted
facility or would be disposed of by incineration or landfilling
at a RCRA treatment storage and disposal facility.
8.3.4 Reduction in Toxicity, Mobility, and Volume
The pumping system would control the mobility of contaminants
present by extracting ground water within the upper aquifer.
Contaminated water would be treated by the air stripping and
carbon adsorption units, thereby reducing the toxicity of the
ground water.
8.3.5 Implementability
Technical Feasibilityt Both air stripping and carbon adsorption
have been used extensively at CERCLA sites and have been
successful in removing organic constituents from ground water.
Design and construction of the necessary treatment units would
not pose a problem. Some equipment manufacturers offer moduler
units that can be made to fit an individual application with
minor modification.
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During operation of the treatment system, the effectiveness of
the treatment process would be monitored by periodically
analyzing constituent concentrations of the treated water prior
to discharge.
This alternative is designed to treat the ground water
contaminants to attain cleanup criteria. Chemical-specific
ARARs were identified and discussed in Section 4.0. Several
Federal and State regulations govern the quality, usage and
discharge of ground water.
Location-Specific; The ground water extraction and treatment
system would be located on the Bluff Road Site which is
proximate to a wetland. Construction of this system as
conceived may impact the wetland. The extent of the impact will
be carefully considered during the remedial design. The impact
to wetlands will be minimized and where it cannot be avoided the
damage will be mitigated.
Action-Specific t This alternative would be designed to comply
with action-specific ARARs. The action-specific ARARs for
construction of the extraction and treatment systems, the
treatment and subsequent disposal of the treated ground water,
and the management of treatment residuals are summarized in
Section 4.0. Many RCRA Subtitle C requirements would apply
because the Bluff Road Site contains hazardous waste. RCRA Part
264 requirements that may apply include standards for owners and
operators of permitted hazardous waste facilities, preparedness
and prevention, contingency plan and emergency procedures,
recordkeeping and reporting, and ground water monitoring.
Federal OSHA worker health and safety requirements would be
applicable to the construction and operation activities.
8.3.7 Overall Protection of Human Health and Environment
This alternative would decrease the potential risks resulting
from direct contact and ingestion of site ground water because
the ground water would be treated to meet the health protective
cleanup criteria. This alternative can be implemented to meet
the identified ARARs.
8.3.8 Cost
The present worth cost for the Air Stripping alternative, would
be approximately $4,339,500. This cost would include a capital
cost of $1,013,000, and estimated annual O&M expenditures of
$306,875. A complete cost summary is included in the final
draft Feasibility Study Report.
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8.4 Effluent Discharge Alternatives;
Effluent from either the air stripper or the GAC will require
discharge of treated water to some location. The alternatives
that have been evaluated as part of completion of the RI/FS
include the following:
- Injection into the subsurface
- Discharge to Myers Creek
- Discharge to the Congaree River
- Spray irrigation into the wetland area
8.4.1 Subsurface Infection of Effluent
Infiltration galleries are a proven and viable alternative for
effluent discharge. The process involves the use of drains,
trenches and/or piping to introduce the treated ground water
into the vadose zone where it is allowed to percolate into the
soil. There are two basic types of infiltration gallaries,
horizontal and vertical. The horizontal system uses trenches
lined with gravel or perforated piping to introduce the ground
water into the vadose zone. Vertical infiltration uses vertical
perforated piping with appropriate packing materials to allow
radial infiltration over the depth of the vadose zone. Due to
the clay content of the soils in the vadose zone, infiltration
galleries may not operate effectively as a discharge alternative
during extended wet periods.
Discharge limitations for subsurface infiltration of the treated
ground water will be the cleanup criteria. This effluent
discharge option would establish the discharge design
requirements for the ground water treatment system.
The effectiveness of this method is dependent on vadose zone
acceptance of the treated water. A preliminary assessment of
infiltration rates based on aquifer and near aquifer vadose zone
soil classification indicates that this technology would be
feasible for the Bluff Road Site.
Percolation testing must be performed to determine permissible
application rates of treated ground water and to establish the
most appropriate process alternative (i.e., horizontal or
vertical). The infiltration gallery must be located so that
recharge to the aquifer does not interfere with the performance
of the extraction system (hydraulic control). These
considerations can be addressed adequately in design. The basis
for conceptual cost evaluation is a horizontal infiltration
galleny. The estimated infiltration area required was
determined using the lowest permeability determined by
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performing slug tests on shallow wells in the upper aquifer (9.27 X
10 cm/sec). This equates to an estimated permissible application
rate of 50 gallons/day/ft2. With an estimated flow rate of 100
gpm, approximately 3000 ft. of infiltration trenches would be
required for horizontal infiltration. The infiltration trenches
would be distributed over an area of approximately 15,000 square
feet. This is based on a trench width of approximately 2 feet and
trench spacing of approximately 7.5 feet (center to center). Again,
permissible application rates would have to be confirmed during
remedial design.
The present worth cost for the infiltration gallery effluent
discharge alternative would be approximately $165,484. This cost
would include a capital cost of $117,656, and estimated annual O&M
expenditures of $4,412. A complete cost summary is included in the
final draft Feasibility Study Report.
8.4.2. Discharge to Myers Creek
The maximum allowable chemical concentrations to a receiving Class A
stream such as Myers Creek or the Congaree River (see Section 5.4.3.
below) would be based on Ambient Water Quality Criteria (where
available) or RFSs.
The volumetric flow of the discharge stream is assumed to be 144,000
gallons per day. The estimated average daily volumetric flow in
Myers Creek is 154,000 gallons per day (IT Corp., 1989).
8.4.3 Discharge to Congaree River
The Congaree River is classified the same as Myers Creek (Class A) .
Maximum allowable chemical concentrations in the treatment system
discharge would be calculated as described in Section 5.3.4.3. of the
final draft Feasibility Study Report.
Discharge of effluent to the Congaree River would require an
extensive overland piping system to transport the water approximately
2 to 3 miles to the river. This would also require access agreements
and easements.
As with Myers Creek, the impacts of the discharge on river levels
(e.g. flood levels) should be evaluated as part of the remedial
design.
8.4.4 Spray Irrigation
Spray irrigation is a procedure by which effluent is discharged
through a surface spray system. Spray irrigation is limited to those
times when the ground is not frozen.
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This alternative would be further evaluated during remedial design if
it appears that the ground water recovery network will impact the
water levels in the wetland area.- The spray irrigation design to
recharge the wetland and offset the impacts of ground water
withdrawal would be difficult due to poor percolation in off-site
surface soils and potential flooding resulting from sheet flow to
down gradient areas. Feasibility of this alternative is considered
marginal.
DETAILED ANALYSIS OF SOIL REMEDIATION ALTERNATIVES
8.5 No Action Alternative
The no action alternative serves as a baseline for comparison of the
overall effectiveness of each soil remediation alternative.
8.5.1 Technical Description
The no action alternative would not utilize any active remedial
technology for the site soils that are currently above the target
cleanup levels. The current interaction between the site soils and
the surrounding environment would be allowed to continue.
According to the Remedial Investigation Report, the principle
environmental and human health threat posed by the site soils is the
effect the soils have on the ground water plume due to leaching of
soil contaminants.
8.5.2 Short Term, Effectiveness
Because remedial action for the soils would not be implemented, there
would be no short-term environmental impacts or risks from activities
associated with this alternative.
8.5.3 Lonq-Term Effectiveness
The baseline risk assessment presented in the Remedial Investigation
Report concluded that the surface soils do not pose an unacceptable
risk to human health or the environment. However, the more highly
contaminated subsurface soils continue to leach contaminants into the
ground water below the site at unacceptable concentrations. The
baseline risk assessment concluded that there are concentrations of
compounds in the ground water that could result in exposure if the
water were to be used as drinking water source.
8.5.4 Reduction of Toxicitv. Mobility, or Volume
The toxicity, mobility, or volume of the contaminants present in the
soils would not be reduced under the no action alternative because no
treatment technologies would be employed.
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8.5.5. Implementability
The no action alternative is technically feasible. This alternative
would not require any special permits to implement.
8.5.6 Compliance with ARARs
Chemical Specific ARARs
There are currently no ARARs for soils. However, because the
contaminated site soils are a source that will further degrade ground
water quality, a soil/water partitioning model (available for review
in the final draft Feasibility Study Report) was used to calculate
cleanup criteria for the soils. The no action alternative would not
meet the calculated cleanup criteria for soils.
Location Specific ARARs
As stated in the detailed analysis for the no action ground water
alternative, the following potential ARARs would apply if the ground
water plume contaminants reached Myers Creek:
o Clean Water Act, Section 404
o Fish and Wildlife Coordination Act
Under the no action soil alternative, these ARARs may potentially
apply if contaminants present in the soils leach into the ground
water plume and subsequently migrate into Myers Creek.
Action Specific ARARs
There are no action specific ARARs for the no action soil remediation
alternative.
8.5.7 Overall Protection of Human Health and the Environment
The no action alternative for soils may increase the potential risks
associated with the ground water plume by contaminant leaching if the
ground water plume is not remedied. There are no direct risks
resulting from the no action soil remediation alternative. The no
action alternative would not meet the calculated cleanup criteria for
soils.
8.5.8 Cost
There are no capital or operational and maintenance costs associated
with the no action alternative. The cost of monitoring the effect of
site soils on the ground water plume are included in the cost for
ground water quality monitoring under the ground water remedial
alternatives.
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8.6. In-Situ Soil Vacuum Extraction (Soil Ventincn
8.6.1 Technology Description
Soil vacuum extraction as proposed herein is an in-situ treatment
process used to clean up soils that contain volatile and some
semi-volatile organic compounds. The process utilizes extraction
wells to induce a vacuum on subsurface soils. The subsurface vacuum
propagates laterally, causing in-situ volatilization of compounds
that are adsorbed to soils. Vaporized compounds and subsurface air
migrate rapidly to extraction wells, essentially air stripping the
soils in-place.
A vacuum extraction system consists of a network of air withdrawal
(or vacuum) wells installed in the unsaturated zone. A pump and
manifold system of PVC pipes is used for applying a vacuum on the air
wells which feed an in-line water removal system, and an in-line
vapor phase carbon adsorption system for VOC removal. Vacuum wells
can either be installed vertically to the full depth of the
contaminated unsaturated zone or installed horizontally within the
contaminated unsaturated zone. If horizontal vacuum wells are
utilized, the wells would require construction by trenching to
mid-depth in the soil column. For the purposes of this evaluation,
vertical wells were selected due to the depth of the soil strata
requiring remediation, geotechnical conditions, and the depth to
groundwater.
Once the well system has been installed and the vacuum becomes fully
established in the soil column, VOCs would be drawn out of the soil
and through the vacuum wells. In all soil venting operations, the
daily VOC removal rates eventually decrease as volatiles are
recovered from the soil. This occurs since volatile recovery
decreases the VOC concentration in the soil, and consequently reduces
the diffusion rate of volatiles from the soil. Volatiles in the air
stream are removed by the carbon adsorption system or destroyed by
fume incineration, after which the cleaned air is discharged to the
atmosphere.
The application of soil venting to the unsaturated zone remediation
is a multi-step process. Specifically, full-scale vacuum extraction
systems are designed with the aid of laboratory and pilot-scale VOC
stripping tests. This would be performed as part of remedial design.
8.6.2 Short-Term Effectiveness
An air dispersion model was used to calculate the ambient air quality
resulting from the organic vapor emissions from the soil venting
system after vapor phase carbon adsorption treatment. The air
dispersion modeling was conducted in accordance with applicable EPA
guidance documents. Based on the results of the air dispersion
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model, a health evaluation was conducted to determine the potential
risks, if any, to public health from inhalation of organic vapors.
The air dispersion model results" and associated health evaluations
are presented in Appendix E of the revised draft Feasibility Study
Report.
The air dispersion modeling for this alternative identified the
downwind location where the maximum one-hour concentrations would be
expected and the location where the maximum annual concentrations
would be expected. The ambient air concentrations for the chemicals
of concern at these locations determine the potential risk, if any,
to public health from the inhalation of organic vapors generated by
the in-situ soil venting process.
The public health evaluation identified the following potential
receptor groups which may experience maximum exposures to airborne
contaminants:
1. Remediation workers in the immediate vicinity of the
soil venting system who might be exposed to
short-term (one-hour) peak concentrations;
2. Remediation workers present at the site for the
duration of the remedial action (18 months) who
might be exposed to airborne contaminants; and
3. Off-site residents who might be exposed to air-
borne contaminants for the duration of the remedial
action (18 months).
For the first receptor group (remediation workers exposed for one
hour to peak concentrations) the maximum predicted one-hour
concentration for each chemical of concern as compared to the
Threshold Limit Values that have been developed by the American
Conference of Governmental and Industrial Hygienists (ACGIH) and
areoccupational exposure criteria that represent airborne
concentrations of substances to which nearly all workers may be
repeatedly exposed without adverse effects. The maximum predicted
one-hour concentrations are far below the Threshold Limit Values for
occupational exposure, therefore, it is concluded that there is no
danger of acute toxicity due to exposure to short-term emissions from
the in-situ soil venting system.
For the second receptor group (remediation workers present at the
site for the duration of the remedial action), the total cancer risk
associated with exposure to maximum concentrations of all the
chemicals of concern is estimated at 1.5 X 10~10 under the
conditions of this scenario presented in Appendix E of the revised
draft Feasibility Study Report. The total hazard index for
non-carcinogenic effects is 1.7 X 10~9 which is far below the 1.0
hazard index value which indicates a potential hazard.
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To represent the third receptor group (off-site residents who might
be exposed for the duration of the remedial action), a child was used
because of higher inhalation rate to body weight ratio, thus
resulting in a worst case exposure scenario. For this receptor
group, the total estimated cancer risk associated with exposure to
maximum concentrations of all the chemicals of concern is 2.1 X
10~^. The total hazard for non-carcinogenic effects is 2.3 X
10~9 which is far below the 1.0 hazard index value which indicates
a potential hazard.
The potential short-term risks to site workers would be the exposure
to drilling fluids and soil during the installation of the soil
venting extraction wells. To mitigate these risks, workers would be
required to comply with a site-specific health and safety plan
(including provisions for protective equipment).
8.6.3 Lono-Term Effectiveness
Magnitude of Residual Risk
The soil venting system would be designed and operated such that
those contaminants in the soil which are considered to be a source of
ground water contamination would be .reduced to the cleanup criteria
identified by the soil partitioning model. Therefore, the soils
would no longer be a source contributing to the ground water plume
and the remedial action objective for soil would be met.
Adequacy and Reliability of Controls
The residues resulting from the treatment system would include spent
carbon used for vapor phase adsorption. This carbon would contain
organic compounds and would be disposed in a RCRA landfill or would
be incinerated. The regeneration of spent carbon would also be a
viable residuals management alternative. The adequacy and
reliability of residuals management would be assured by using a
permitted regeneration facility or a RCRA treatment, storage, and
disposal facility.
8.6.4 Reduction of Toxicity. Mobility, and Volume
Soil vacuum extraction would significantly reduce the volume of
volatile organic contaminants in the soil. Results of the plant test
at the site indicated significant quantities of semi-volatile organic
compounds will be removed, reducing to volume of these contaminants
in the soil.
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8.6.5 Implementability
Technical Feasibility
In-situ soil vacuum extraction is a proven technology and has been
applied in both pilot test and full scale remediation programs for
stripping volatile organic and a limited number of semi-volatile
compounds from unsaturated soils and bedrock. The organic vapor
treatment facilities (i.e. vapor phase carbon adsorption or fume
incineration) have also been successfully implemented. Golder (1986)
conducted laboratory testing on contaminated soils which showed that
the affected site soils are amenable to air stripping. Pilot tests
indicate that some semi-volatile compound removal does occur during
the vacuum process. During operation, the effectiveness of the
system would be monitored by periodically analyzing contaminant
concentration of the following:
o Treated Soil
o Untreated Vapor Entering the System
o Treated Vapor
Administrative Feasibility;
This alternative would require compliance with EPA, U.S. Department
of Transportation, and SCDHEC regulations regarding transportation
and disposal of hazardous materials (i.e. spent carbon). SCDHEC may
require permits for the vapor discharge.
8.6.6 Compliance with ARARs
Chemical Specific; Implementation of this alternative would achieve
the cleanup criteria for volatile organic compounds in the soils as
identified in the soil partitioning model. It is uncertain as to
whether or not the technology would achieve cleanup criteria for the
semi-volatiles, however, the pilot test indicates semi-volatile
organic compounds may be removed by this process.
Action-Specific; The alternative would be designed, constructed and
operated to comply with action-specific ARARs. The action-specific
ARARs for construction of the extraction and treatment system, the
treatment and disposal of treated vapor, and disposal of residuals
(spent carbon) are summarized in the revised draft Feasibility Study
Report (Table 3-5). Federal OSHA worker health and safety
requirements would be applicable to the construction and operation
activities and would be compiled with by adhering to an approved work
plan and health and safety plan. Many RCRA requirements may apply
because the Bluff Road Site contains hazardous waste. RCRA Part 264
requirements that may apply include standards for owners and
operators of permitted hazardous waste facilities, preparedness and
prevention, contingency plan and emergency procedures, recordkeeping
and reporting.
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It is anticipated that this alternative would comply with applicable
portions of the Clean Air Act and the South Carolina Pollution
Control Act.
8.6.7 Overall Protection of Human Health and the Environment
This alternative would decrease the potential risks associated with
the migration of organic contaminants into ground water from the
soils.
8.6.8 Cost
The estimated total cost for the soil vacuum extraction system with
vapor phase carbon adsorption would be approximately $1,070,000.
This capital cost includes the anticipated O&M expenditures since
this remedial action is not expected to last over 2 years.
Capital cost would include construction of the soil vapor extraction
system, vapor treatment system, and all associated piping/mechanical
facilities.
8.7 High Temperature Incineration
8.7.1 Technical Description
This alternative consists of excavation and treatment of the
contaminated soils on-site using high temperature incineration. This
treatment technology has been proven effective at treating soils that
contain elevated levels of organic contaminants. Prior to initiation
of this remedial alternative, supplementary soil sampling would be
performed to adequately delineate the volume of soil present above
the target clean-up levels. Approximately 23,000 to 45,000 cubic
yards of soil at the site is estimated to be above the cleanup
criteria.
Process Description
For the development of this alternative, the representative process
option for high temperature incineration is the commercially
available transportable rotary kiln incineration system.
This system uses a rotating refractory lined kiln to treat solids,
soils, sludges and liquid wastes. The kiln is approximately 8 feet
in diameter and 60 feet long. The soils would be heated to 1200°F
to 1500°F by 60 mm BTU per hour oil fired fuel burners. The
rotating kiln serves to mix, convey, and agitate the contaminated
soil. After processing, the treated soil would be discharged from
the kiln into a pug mill where it is moisturized by the addition of
water to reduce dusting.
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During incineration, combustion gas leaves the kiln at 1400°F to
1600°F and contains partially combusted organics, acid gases,
entrained soil particles, and ash particulate. The combustion gas
would pass through a hot cyclone for removal of relatively large
particulates and would flow into a secondary combustion chamber
(SCC). The SCC completes the combustion of the organic vapors from
the soil by exposing the remaining organic vapors, carbon monoxide
(CO) and carbonaceous particulates to temperatures in the range of
1800°F to 2200°. The SCC is sized for a combustion gas
residence time of at least two seconds at 2200°F.
For the organics present in the site soils, a temperature of 1800°F
should be adequate to produce destruction and removal efficiencies
(DREs) of at least 99.99%. The operational temperature necessary to
achieve DREs of at least 99.99% would be determined during a
pre-operational trial burn. The SCC will be fired by a 40 mm BTU per
hour burner.
The combustion gas would leave the SCC at approximately 1800°F and
enter the air pollution control (APC) system. The APC system would
include an evaporative cooler, a baghouse, and a packed bed alkaline
scrubbing unit.
The purge stream from the packed bed would be used for the
evaporative cooler. Salts such as sodium chloride and sodium
sulfate, which are formed in the packed bed, would be evaporated in
the evaporative cooler and removed by a fabric filter. The
combustion gas would leave the evaporative cooler at 300°F to
350°F, and enter the fabric filter where most of the remaining
particulate would be removed. The combustion gas would then enter
the packed bed for alkaline scrubbing removal of most of the acid
gases. The combustion gas would exit the packed bed at approximately
185°F and enter the induced draft (ID) fan. The ID fan pulls the
combustion gas through the entire incineration system and exhausts
the combustion gas to the stack and out to the atmosphere. Stack
emissions would be continuously monitored for carbon monoxide,
oxygen, and the combustion gas velocity to verify compliance with
Federal and State Regulations. An automatic waste feed cutoff system
would be tied into various incinerator monitoring parameters such as
temperature, carbon monoxide and waste feed rates in accordance with
40 CFR 264 Subpart 0 regulations and appropriate guidance documents.
The system requires an area of two to three acres. The soil would be
processed at a rate of approximately 20 tons per hour (for soil with
a moisture content of about 20 percent). At an operating factor of
about 80%, 190 days of continuous operation would be required to
treat 72,900 tons (45,000 cubic yards) of soil. Mobilization,
demobilization and decontamination of the incineration equipment will
take about 60 days. Therefore implementation of on-site high
temperature incineration is expected to take less than one year from
the initial mobilization and start-up.
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Site Preparation and Preprocessing
Prior to excavation, the site would be cleared of vegetation. Any
existing foundations or concrete pads would be decontaminated and
disposed accordingly.
Excavation and teatment would proceed in stages. The excavation rate
should match the treatment rate in order to minimize the storage
space required. Water spray would be used for dust control, if
necessary. Vapor suppression foams or some other form of emission
control would be used if high levels of organic vapors in the
breathing zone are detected during excavation. The excavated soil
would be preprocessed in a tent structure of pole-barn construction
and placed in containers or tanks as required by the RCRA definition
of storage. The storage space should be sized for adequate
processing capacity to assure continuous operation during inclement
weather.
The soil would be removed from the storage area in the tent using a
covered belt conveying system and would drop into a hopper over a
scalping screen or shedder to remove oversized (greater than 2-inch)
material and debris. The sorted material would then be transported
by an enclosed drag conveyor to a hopper that directly feeds the
incinerator. Rocks and other large objects would be screened and
removed from the feed system, stockpiled on a pad, and decontaminated
by steam cleaning. These materials would then be used as backfill
on-site, after confirmatory sampling to assure adequate
decontamination.
Residuals Treatment
Purge water from the scrubber would be recycled to the evaporative
cooler where it would be evaporated. The salts and suspended solids
contained in the purge water would be captured in the fabric filter.
Solids from the cyclone and fabric filter would be mixed with the
treated soil after analytical testing verifies the absence of organic
compounds and metals. If the solids are unacceptable for mixing with
the soil, they would be stabilized and disposed off-site.
The treated soils would also be analyzed for the presence of organic
compounds and TCLP Metals. If the treated soils fail to meet these
criteria, the soils would be stabilized prior to backfilling.
8.7.2 Short-Term Effectiveness
Potential risks to public health and the environment are associated
with the excavation and treatment of the contaminated soils.
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Air pollution control systems would be an integral part of the
on-site high temperature incinerator to limit air emissions to within
the regulatory requirements. Stack and site perimeter monitoring
will ensure that the discharge limits are not exceeded. An air
dispersion model was used to calculate the ambient air quality
resulting from the anticipated incineration air emissions (after
treatment with air pollution control systems). The air dispersion
model was conducted in accordance with applicable EPA guidance
documents. Based on the results of the air dispersion model, a
health evaluation was conducted to determine the potential risks, if
any, to public health from the inhalation of emitted compounds. The
air dispersion model results (including associated input data
calculations) and the health evaluations are presented in Appendix F
of the revised draft Feasibility Study Report.
The air dispersion modeling for this alternative identified the
downwind location where the maximum one-hour concentrations would be
expected and the location where the maximum annual concentrations
would be expected. The ambient air concentrations for the chemicals
of concern at these locations determined by the air dispersion model
were used to determine the potential risk, if any, to public health
from the inhalation of emitted compounds generated by the high
temperature incineration process.
The public health evaluation identified the following potential
receptor groups which may experience maximum exposures to airborne
contaminants;
1. Remediation workers in the immediate vicinity of
the incinerator who might be exposed to short-term
(one hour) peak concentrations;
2. Remediation workers present at the site for the
duration of the remedial action (200 days) who
might be exposed to airborne contaminants; and
3. Off-site residents who might be exposed to air-
borne contaminants for the duration of the
remedial action. (200 days)
For the first receptor group (remediation workers exposed for one
hour to peak concentrations) the maximum predicted one-hour
concentrations for each chemical of concern were compared to the
Threshold Limit values for those chemicals. Threshold Limit Values
have been developed by the American Conference of Governmental and
Industrial Hygienist (ACGIH) and are occupational exposure criteria
that represent airborne concentrations of substances to which nearly
all workers may be repeatedly exposed without adverse effects. The
maximum predicted one-hour concentrations are far below the Threshold
Limit Values for occupational exposure, therefore, it is concluded
that there is no danger of acute toxicity due to exposure to
short-term emissions from the high temperature incinerator.
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For the second receptor group (remediation workers present at the
site for the duration of the remedial action), the total cancer risk
associated with exposure to maximum concentrations of all the
chemicals of concern is estimated at 1.7 X 10~7 under the
conditions of this scenario presented in the revised draft
Feasibility Study Report. The total hazard index for
non-carcinogenic effects is 4.9 X 10 which is far below the 1.0
hazard index value which indicates a potential hazard.
To represent the third receptor group (off-site residents who might
be exposed for the duration of the remedial action), a child was used
because of higher inhalation rate to body weight ratio, thus
resulting in a worst case exposure scenario. For this receptor
group, the total estimated cancer risk associated with exposure to
maximum concentrations of all the chemicals of concern is 2.2 X
10"J. The total hazard index for non-carcinogenic effects is 6.6 X
10 which is far below the 1.0 hazard index value which indicates
a potential hazard.
Short term emissions of dust and organic vapors may occur during the
excavation and pretreatment activities. These emissions may be
mitigated by the proper use of water sprays, foams, and vapor control
techniques Downwind air monitoring for organics will be used to
detect any off-site air emissions. In addition, risks to workers may
occur because of contaminant volatilization during waste excavation,
and at the processing and stockpile areas. Workers involved with the
waste excavation and processing activities may also be exposed to the
additional risks associated with dermal contact with contaminated
soils. Therefore, all workers would be required to wear appropriate
protective equipment, as specified in the site specific health and
safety plan.
8.7.3 Long-Term Effectiveness
Magnitude of Residual Risks The treated soil would be tested for
leaching potential and organic compounds to ensure treatment to
established clean-up levels is achieved. Treatability testing would
be conducted to determine the expected organic and metal
concentrations after treatment.
Adecruacy of Controls Data available from vendors indicates an
organic removal rate of 99.99 percent or greater is achievable by
high temperature incineration. Therefore, it is expected that the
clean-up criteria can be achieved by this technology.
Reliability of Controls The removal of organic compounds from the
soil followed by incineration of the vapors is a permanent process.
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8.7.4 Reduction in Mobility, Toxicitv. or Volume
The thermal destruction of organic compounds from the soils provides
the multiple benefit of reducing the toxicity, mobility, and volume
of the organic compounds present in the soil. Destruction of at
least 99.99% of the organics vaporized from the soil would be
expected. The treatment process is irreversible and the treated soil
is expected to meet the soil remediation goals. The volume of soil
may be less than was processed in the system.
8.7.5 Implementability
Technical Feasibility The high temperature rotary kiln incineration
process has been used in many projects to treat organic compounds
present in soil. The soils present at these sites were treated to
meet the respective remedial action objectives and the incineration
processes were conducted to comply with the applicable ARARs.
Administrative Feasibility Acquisition of regulatory permits may not
be required. However, the documentation for technical permit
requirements would be provided to EPA for approval prior to
implementation of any remedial activities.
Currently, three vendors are known to have a total of five mobile
rotary incineration systems in this size category. Treatment units
are available that would have sufficient capacity to perform soils
treatment at the site within a reasonable period of time. Advanced
scheduling would be required to ensure that a mobile incineration
system is available.
8.7.6 Compliance with ARARs
Chemical Specific ARARs
This alternative is expected to meet the calculated clean-up criteria
for soils. The site soils above the cleanup criteria would be
excavated and treated by high temperature incineration to those
concentrations.
Action Specific ARARs
Action specific ARARs for this alternative apply to the excavation of
contaminated soils, monitoring requirements, and operation of a
thermal treatment unit. Workers and worker activities that would
occur during the implementation of this alternative must comply with
the OSHA requirements for training, safety equipment and procedures,
monitoring, recordkeeping, and reporting. In addition, the RCRA
requirements for preparedness and prevention, contingency plans, and
emergency procedures would also apply to this alternative.
Compliance with the above mentioned ARARs would be achieved by
following an EPA approved work plan and a site-specific health and
safety plan.
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The RCRA standards for permitted hazardous waste facilities,
including performance standards (.40 CFR 264), may apply to the high
temperature incineration unit. To achieve compliance with these
ARARs, the unit used would be designed, constructed, and operated in
accordance with the provisions contained in the RCRA hazardous waste
facility regulations.
This alternative would result in air emissions. The applicable
requirements for air emissions would be the Prevention and
Significant Deterioration (PSD) air emission provision contained in
the Clean Air Act and the requirements contained in the South
Carolina Pollution Control Act. It is anticipated that the treatment
system will not exceed the PSD limits and would comply with South
Carolina Pollution Control Act requirements for air emissions. The
action specific ARAR of the RCRA Land Disposal Restrictions would be
met if the cleanup criteria in Tables 3-3 and 3-4 are met.
8.7.7 Overall Protection of Human Health and the Environment
This alternative would destroy the organic contaminants present in
the soils thus reducing the toxicity, mobility, and volume of the
contaminants. Therefore, this alternative would meet the remedial
action objectives for soil. Protection of human health and the
environment would be achieved by meeting the remedial objectives and
by complying with the identified ARARs.
8.7.8 Cost
The capital cost associated with this alternative include site
preparation, incineration unit mobilization and demobilization, pilot
testing, the construction of support facilities, soil excavation and
treatment, site restoration, and a mobile laboratory. Due to the
short implementation period associated with this alternative the
operation and maintenance cost for this alternative are incorporated
in the capital cost. Therefore, a present worth analysis has not
been performed for this alternative. The estimated cost of this
alternative (based on 45,000 cubic yard of soil) is $28,260,000. A
detailed breakdown of the estimated costs associated with this
alternative are presented in the final draft Feasibility Study
Report.
8.8. Low Temperature Thermal Desorption
8.8.1 Technical Description
This alternative consists of excavating the site soils and treating
the soils on-site using low temperature thermal desorption. This
treatment technology has been proven effective at treating soils that
contain elevated levels of organic contaminants. Approximately
16,000 to 45,000 cubic yards of soil at the site is estimated to be
above the target clean-up levels. Prior to initiation of this
remedial alternative, supplementary soil sampling would be performed
to adequately delineate the volume of soil present above these
levels.
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Process Description
For the development of this alternative, the representative process
option for low temperature thermal desorption is the commercially
available modified asphalt kiln. This system uses a rotating kiln
with soil lifters inside the kiln to mechanically agitate the soil
and improve heat transfer. The kiln is approximately 8 feet in
diameter and 40 feet long. The soil would be heated to approximately
600°F by a 50mm BTU per hour fuel oil burner firing in the kiln.
The rotating kiln and lifters serve to mix, convey, and agitate the
contaminated soil, allowing the moisture and organic compounds to
vaporize and escape from the soil. After processing, the soil would
be discharged from the kiln into a pug mill where it is moisturized
by the addition of water to reduce dusting problems.
The combustion gas leaves the kiln at about 300 to 400°F and
contains vaporized organic compounds and extrained soil particles.
The combustion gas would pass through a cyclone, a baghouse, a wet
scrubber, and a bed of granular activated carbon. The cyclone and
baghouse remove the soil particulates. The wet scrubber removes acid
gases, and the carbon bed removes any remaining organic compounds.
Stack emissions would be monitored to verify compliance with federal
and state regulations, including those for volatile organic
compounds, hydrochloric acid (HC1), carbon monoxide (CO) and
particulate loading.
The system requires an area of about 100 feet by 100 feet. The
equipment is assembled on seven trailers for easy transportation.
The soil would be processed at a rate of approximately 40 tons per
hour (for soil with a moisture content of approximately 20 percent).
At an operating factor of about 80%, approximately 95 days of
continuous operation would be required to treat 72,000 tons (45,000
cubic yards) of soil. Mobilization, demobilization and
decontamination of the low temperature desorption equipment will take
about 30 days. Therefore, implementation of on-site low temperature
thermal desorption is expected to take less than one year.
Site Preparation and Preprocessing
Prior to excavation, the site would be cleared of vegetation. Any
existing foundations or concrete pads would be decontaminated and
disposed accordingly. Excavation and treatment will progress in
stages. The excavation rate should match the treatment rate in order
to minimize the storage space required. Water spray would be used
for dust control, if necessary. Vapor suppression foams would be
used if high levels of organic vapors in the breathing zone are
detected during excavation. The excavated soil would be preprocessed
in a tent structure of pole-barn construction and placed in
containers or tanks. The storage space should be sized for adequate
processing capacity to assure continuous operation during inclement
weather.
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The soil would be removed from the storage area in the tent using a
covered belt conveying system and would drop into a hopper over a
scalping screen or shredder to remove oversized (greater than 2-inch)
material and debris. The sorted material would then be transported
by an enclosed drag conveyor to a hopper that directly feeds the low
temperature thermal desorption unit.
Rocks and other large objects would be screened and removed from the
feed system, stockpiled on a pad, decontaminated by steam cleaning.
These materials would then be used as backfill on-site, after
confirmatory sampling to assure adequate decontamination.
Residuals Treatment
The water from the wet scrubber would be treated with a two-stage
carbon adsorption system, and then used for ash quenching. Spent
carbon from the system would be sent to an off-site hazardous waste
incinerator for disposal. Soil particles from the cyclone and
baghouse would be mixed with the treated soil from the thermal
adsorber after analytical testing verifies the absence of organic
compounds and metals. The excavated area would be backfilled with
the treated soil. The treated soil would be analyzed for organic
compounds prior to backfilling. If treated soil contains organic
compounds above the clean-up criteria, then these soils would be
recycled back into the treatment unit. The treated soils would also
be analyzed for TCLP metals. If the treated soils fail to meet these
criteria, the soils would be stabilized prior to backfilling. The
treated soil would have sufficient properties to allow for standard
grading and compaction equipment for backfilling operations. The
area would be graded to match with existing drainage, covered with
one foot of topsoil, and revegetated to minimize erosion.
8.8.2 Short-Term Effectiveness
Potential risks to public health and the environment are associated
with the excavation and treatment of the contaminated soils.
Air pollution control systems will be an integral part of the low
temperature thermal desorption system to limit air emissions to
within the regulatory requirements. Stack and site perimeter
monitoring will ensure that the discharge limits are not exceeded.
An air dispersion model was used to calculate the ambient air quality
resulting from the anticipated thermal desorption air emissions
(after treatment with air pollution control systems). The air
dispersion modeling was conducted in accordance with applicable EPA
guidance documents. Based on the results of the air dispersion
model, a health evaluation was conducted to determine the potential
risk, if any, to public health from the inhalation of emitted
compounds. The air dispersion model results (including associated
input data calculations) and the health evaluations are presented in
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Appendix G of the revised draft Feasibility Study Report. The air
dispersion modeling for this alternative identified the downwind
location where the maximum one-hour concentrations would be expected
and the location where the maximum annual concentrations would be
expected. The ambient air concentrations for the chemicals of
concern at these locations determined by the air dispersion model
were used to determine the potential risk, if any, to public health
from the inhalation of emitted compounds generated by the thermal
desorption process.
The public health evaluation identified the following potential
receptor groups which may experience maximum exposures to airborne
contaminants;
1. Remediation workers in the immediate vicinity of the
thermal adsorber who might be exposed to short-term
(one hour) peak concentrations;
2. Remediation workers present at the site for the
duration of the remedial action (100 days) who
might be exposed to airborne contaminants; and
3. Off-site residents who. might be exposed to airborne
contaminants for the duration of the remedial action
(100 days).
For the first receptor group (remediation workers exposed for one
hour to peak concentrations) the maximum predicted one-hour
concentrations for each chemical of concern were compared to the
Threshold Limit Values for those chemicals. Threshold Limit Values
have been developed by the American Conference of Governmental and
Industrial Hygienists (ACGIH) and are occupational exposure criteria
that represent airborne concentrations of substances to which nearly
all workers may be repeatedly exposed to without adverse effects.
The maximum predicted one-hour concentrations are far below the
Threshold Limit Values for occupational exposure, therefore, it is
concluded that there is no danger of acute toxicity due to exposure
to short-term emissions from the thermal desorption unit.
For the second receptor group (remediation workers present at the
site for the duration of the remedial action), the total cancer risk
associated with exposure to maximum concentrations of all the
chemicals of concern is estimated at 4.3 X 10 under the
conditions of this scenario presented in Appendix F of the revised
draft Feasibility Study Report. The total hazard index for
non-carcinogenic effects is 9.1 X 10 which is far below the 1.0
hazard index value which indicates a potential hazard.
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To represent the third receptor group (off-site residents who might
be exposed for the duration of the remedial action) , a child was used
because of higher inhalation rate to body weight ratio, thus
resulting in a worst case exposed scenario. For this receptor group,
the total estimated cancer risk associated with exposure to maximum
concentrations of all the chemical of concern is 5.7 X 10~ . The
total hazard index for non-carcinogenic effects is 1.2 X 10~^ which
is below the 1.0 hazard index value which indicates a potential
hazard.
Short term emissions of dust and organic vapors may occur during the
excavation and pretreatment activities. These emissions may be
mitigated by the proper use of water sprays, foams, and vapor control
techniques. Downwind air monitoring for organics will be used to
detect any off-site air emissions.
In addition, risks to workers may occur because of contaminant
volatilization during excavation, and at the processing and stockpile
areas. Workers involved with the waste excavation and processing
activities may also be exposed to the additional risks associated
with dermal contact contaminated soils. Therefore, all workers would
be required to wear appropriate protective equipment, as specified in
the site specific health and safety.plan.
Short term emissions of dust, and organic vapors, may occur during
the excavation and pretreatment activities. These emissions would be
mitigated by the proper use of water sprays, foams, and vapor control
techniques. Downwind air monitoring for organic compounds will be
used to detect any off-site air emissions.
8.8.3 Loncr-Term Effectiveness
Magnitude of Residual Risks;
The treated soil would be tested for organic compounds to ensure
treatment below established clean-up levels is achieved. Since the
extraction efficiency for volatile organics is expected to be high,
treatment residuals are not expected to contain organic contaminants
above the clean-up criteria. Treatability testing would be conducted
during remedial design to determine the expected organic
concentrations after treatment. Carbon used for vapor treatment
would be disposed of off-site at a RCRA incineration and/or landfill
facility or would be regenerated at an approved facility.
Adequacy and Reliability of Controls;
Data available from a vendor indicates a volatile organic removal
rate of 99.9 percent or greater is achievable by low temperature
thermal desorption. Therefore, it is expected that the clean-up
levels can be achieved by this technology. The removal of volatile
organics from the soil by low temperature thermal desorption followed
by the carbon bed adsorption of the collected vapors is a permanent
process.
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The spent carbon or carbon regeneration waste would be disposed at a
permitted RCRA incineration and/or landfill facility to ensure
adequate management of the treatment residuals.
8.8.4 Reduction in Mobility, Toxicity. or Volume
This alternative provides the multiple benefit of reducing the
toxicity and mobility of organic contaminants present in the soil.
The treatment process is irreversible and the treated soil is
expected to meet the soil remediation goals. The volume of treated
soil may be less than was processed in the system.
8.8.5 Implementability
Technical Feasibility;
The low temperature thermal desorption process has been used in
several projects to treat organic compounds in soil. The system is
commercially available through several vendors as trailer mounted
transportable systems. The thermal desorption process has been used
at a number of CERCLA sites.
Administrative Feasibility;
Acquisition of regulatory permits may not be required, although
documentation for meeting the technical permit requirements would be
provided to EPA for approval prior to implementation of remedial
activities. The thermal desorption process has been used at a number
of CERCLA sites.
Currently, five vendors are known to own low temperature desorption
process equipment. Therefore, treatment units are available that
would have sufficient capacity to perform soils treatment at the site
within a reasonable period of time. Advanced scheduling will be
required to ensure that a low temperature thermal desorption unit is
available.
8.8.6 Compliance With ARARs
Chemical Specific ARARs
This alternative is expected to meet the calculated clean-up criteria
for soils. The site soils above the cleanup criteria would be
excavated and treated by low temperature thermal desorption.
Action Specific ARARs
Action specific ARARs for this alternative apply to the excavation of
contaminated soils, monitoring requirements, and operation of a
thermal treatment unit.
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Workers and worker activities that would occur during the
implementation of this alternative must comply with the OSHA
requirements for training, safety equipment and procedures,
monitoring, recordkeeping, and reporting. In addition, the RCRA
requirements for preparedness and prevention, contingency plans, and
emergency procedures would also apply to this alternative.
Compliance with the above mentioned ARARs would be achieved by
following an EPA approved work plan and a site-specific health and
safety plan.
The RCRA standards for permitting hazardous waste facilities
including performance standards (40 CFR 264) would apply to the low
temperature thermal desorption unit. To achieve compliance with
these ARARs, the unit used would be designed, constructed, and
operated in accordance with the provisions contained in the RCRA
waste facility regulations.
This alternative will result in air emissions. The applicable
requirements for air emissions would be the Prevention and
Significant Deterioration (PSD) air emission provisions contained in
40 CFR 51 and the requirements contained in the South Carolina
Pollution Control Act. It is anticipated that the treatment system
will not exceed the PSD limits and will comply with South Carolina
Pollution Control Act requirements for air emissions.
The action specific ARAR of the RCRA Land Disposal Restrictions would
apply for the backfilling of treated soils at the Bluff Road site.
The cleanup criteria in the ROD (Tables 3-3 and 3-3) are below the
LDR treatment standards (and the applicable Toxicity Characteristic
levels).
The activated carbon, which would contain elevated levels of organic
compounds, would be transported and incinerated off-site. The RCRA
and U.S. Department of Transportation requirements for the packaging
and transportation of hazardous waste would be applicable.
Compliance with these ARARs would be complied with by disposing of
the carbon at an EPA permitted RCRA incineration facility.
8.8.7 Overall Protection of Human Health and the Environment
This alternative would remove the organic contaminants from the soil
to meet the remedial objectives for soil. The toxicity, mobility,
and volume of the contaminants present in the soil would be reduced.
Protection of human health and the environment would be achieved by
complying with the identified ARARs.
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8.8.8 Costs
The capital costs associated with this alternative include site
preparation, thermal treatment unit mobilization and demobilization,
pilot testing, construction of support facilities, soil excavation
and treatment, backfilling, revegetation, mobile laboratory, and
environmental monitoring. Due to the short implementation period
associated with this alternative the operational and maintenance
costs for this alternative are incorporated in the capital costs.
Therefore, a present worth analysis has not been performed for this
alternative. The estimated cost of this alternative (based on 45,000
cubic yards of soil) is $18,250,000. A detailed breakdown of the
estimated costs associated with this alternative are presented in the
final draft Feasibility Study Report.
8.9. Soil Excavation and Off-Site Disposal
8.9.1. This alternative consists of excavating the site soils that
are above the clean-up criteria and transporting the excavated soils
to an off-site RCRA landfill for disposal. Prior to initiation of
the remedial design for this alternative, supplementary soil sampling
would be performed to adequately delineate the volume of soil present
above the target clean-up levels. Approximately 16,000 to 45,000
cubic yards of soil is estimated to be above the clean-up criteria at
the site.
Prior to excavation, the site would be cleared of vegetation. Any
existing foundations or concrete pads would be decontaminated and
disposed accordingly.
An equipment staging area would be constructed for equipment
storage. In addition, a mobile analytical laboratory would be
installed on-site and used to provide quick turn around on soil
sample analyses to verify that the affected site soils have been
adequately removed. Excavation at the site is expected to be routine
and would be accomplished using conventional construction equipment.
Excavated soil would be placed directly into lined 20 cubic yard
capacity trucks. Trucks would be decontaminated prior to leaving the
site. Disposal of the site soils would be accomplished at a RCRA
landfill. Analytical testing of the soils with the Toxicity
Characteristic Leaching Procedure (TCLP) will be required to
determine if the soils can be disposed of untreated in a RCRA
landfill in accordance with the RCRA Land Disposal Restrictions (40
CFR 268). The Land Disposal Restrictions go into effect for CERCLA
soils in May, 1992. If the soil cannot be land disposed, then
pretreatment of the soils (i.e. solidification/fixation) would be
required.
The excavated areas would be backfilled with clean fill/backfill
material. A one-foot layer of topsoil would also be installed. The
site would be graded to promote drainage and would be revegetated.
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8.9.2 Short-Term Effectiveness
Potential risks posed to the community and the environment from
volatilized organics or dust would be mitigated by the use of water
sprays and foam suppressants during the remedial action. In
addition, downwind air sampling would be performed to monitor any
off-site emissions of volatile organics.
A site-specific health and safety plan (including protective
equipment and monitoring equipment to be used) would be prepared and
adhered to during the remedial action to minimize risks posed to
workers.
To reduce the potential risks to public health or the environment
resulting from an accident during transportation of the soils, a
traffic control plan including routing of trucks to avoid populated
areas would be developed and followed.
8.9.3 Long-Term Effectiveness
Magnitude of Residual Risks
Upon removal and disposal of the site soils that are above the
clean-up criteria, the soil remediation objective will be achieved.
Therefore, the leaching potential of the site soils into the
groundwater plume would be eliminated.
Adequacy of Controls
There would be no soils left at the site that have concentrations
above the clean-up criteria, therefore monitoring of the backfill and
remaining site soils is not necessary. The ground water plume would
be monitored no matter which ground water remedial action is
implemented.
Reliability of Controls
Disposal of the excavated soils at a RCRA landfill would effectively
isolate the contaminants of concern presented in the soils.
Monitoring programs required at RCRA landfills are designed to detect
potential failures so that corrective actions can be undertaken to
mitigate the threat of a release.
8.9.4 Reduction of Toxicity, Mobility, or Volume
If no treatment technology (i.e. stabilization to meet Land Ban
requirements) is employed, there would be no reduction in toxicity or
volume of the contaminants. However the mobility of the contaminants
would be decreased by placing the soils in a RCRA landfill.
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8.9.5 Implementability
Technical Feasibility
Excavation and transportation of contaminated soils are common
construction activities, and are considered technically feasible.
The removal and transport of the contaminated soils is limited by the
removal/excavation rate and/or the rate at which the materials can be
accepted at the RCRA landfill facility. A waste profile sheet and a
statement certifying the material as nonreactive must be provided to
the landfill facility before the waste can be accepted.
RCRA manifest requirements must be complied with for all wastes
shipped off-site. Effective May 8, 1992, discarded commercial
chemical product contaminated soil and debris are prohibited from
land disposal without treatment if the soils contain contaminants
above certain limits established in 40 CFR 268. Pretreatment of the
soils may be necessary at the site or may be accomplished at the
disposal facility. The Land Disposal Restriction regulations will
significantly increase the cost of disposed soils by landfilling.
Administrative Feasibility
Implementation of this alternative may require coordination with
municipalities to determine the appropriate transportation routes.
Numerous remedial action contractors and hazardous waste transporters
are available for the excavation and transportation of the site
soils. Coordination and advanced planning is required to ensure that
capacity is available at a RCRA landfill.
8.9.6 Compliance with ARARs
Chemical Specific ARARs
Action specific ARARs for this alternative apply to the excavation of
contaminated soils, monitoring requirements, and transportation and
disposal requirements.
Workers and worker activities that would occur during the
implementation of this alternative must comply with the OSHA
requirements for training, safety equipment and procedures,
monitoring, recordkeeping and reporting. Also, the RCRA requirements
for preparedness and prevention, contingency plans, and emergency
procedures would apply to this alternative. Compliance with the
above mentioned ARARs would be achieved by following an EPA approved
work plan and a site-specific health and safety plan.
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The action specific ARARs for disposal of soils in a RCRA landfill
resulting from a CERCLA remedial activity are the RCRA Land Disposal
Restriction regulations in 40 CFR 268 (effective November 1990). The
site soils would be analyzed for EP toxicity metals and TCLP
parameters. If the soils are above the concentration limits
acceptable for disposal in a RCRA landfill, then pretreatment of the
soils to meet the land disposal regulations would be required to
comply with this ARAR.
The RCRA and U.S. Department of Transportation requirements for the
packaging and transportation of hazardous waste would be applicable
to this alternative. Compliance with these ARARs would be achieved
by utilizing a licensed hazardous waste transporter.
8.9.7 Overall Protection of Human Health and the Environment
The excavation of the site soils and subsequent disposal in a RCRA
landfill would meet the soil remediation objectives. The mobility of
the soil contaminants would be reduced by placement of the soils in a
RCRA landfill. Protection of human health and the environment would
be achieved by complying with the identified ARARs.
8.9.8 Cost
The capital costs associated with the alternative include site
preparation, excavation, transportation and disposal costs, and site
restoration. Because of the relatively short implementation period
associated with this alternative, operational and maintenance costs
are incorporated in the capital cost. Therefore, a present worth
analysis has not been performed for this alternative. The
established cost of this alternative (based on 45,000 cubic yards of
soil) is $20,700,000. A detailed breakdown of the estimated costs
associated with this alternative are presented in the final draft
Feasibility Study Report,
8.10. Soil Excavation and Off-Site Thermal Treatment
8.10.1 Technical Description
This alternative consists of excavating the site soils that are above
the clean-up criteria and transporting the excavated soils to an
off-site RCRA incinerator for treatment and disposal. Prior to
initiation of the remedial design for this alternative, supplementary
soil sampling would be performed to adequately delineate the volume
of soil present above the clean-up criteria. Approximately 16,000 to
45,000 cubic yards of soil is estimated to be above the clean-up
criteria at the site.
Prior to excavation, the site would be cleared of vegetation. Any
existing foundations or concrete pads would be decontaminated and
disposed of accordingly. An equipment staging area would be
constructed of equipment storage. In addition, a mobile analytical
laboratory would be installed on-site and used to provide quick turn
around on soil samples to verify that the affected site soils have
been adequately removed.
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Excavated soil would be placed directly into lined 20 cubic yard
capacity trucks. Trucks would be decontaminated prior to leaving the
site. Thermal treatment of the-soil would be completed at a
RCRA-permitted incineration facility. Treated soil would then be
disposed of in a landfill (most incineration facilities have
associated landfills for disposal of treated wastes).
The excavated areas would be backfilled with clean fill/backfill
material. A one-foot layer of topsoil would also be installed. The
site would be graded to promote drainage and would be revegetated.
8.10.2 Short-Term Effectiveness
Potential short-term risks to public health and the environment are
associated with the excavation and handling of the contaminated
soil. Potential risks to the public may result from inhalation of
volatilized contaminants or fugitive dust during excavation and from
accidents during transportation of excavated soil. The potential
risks posed to the community and the environment from volatilized
organics or dust would be mitigated by the use of water sprays and
foam suppressants during the remedial action. In addition, downwind
air sampling would be performed to monitor any off-site emissions of
volatile organic compounds.
A site-specific health and safety plan (including protective
equipment and monitoring equipment to be used) would be prepared and
adhered to during the remedial action to minimize risks posed to
workers.
To reduce the potential risks to public health or the environment
resulting from an accident during transportation of the soils, a
traffic control plan including routing of trucks to avoid populated
areas would be developed and implemented.
8.10.3 Lonq-Term Effectiveness
Magnitude of Residual Risks
The soil remediation objectives will be achieved upon the excavation
and disposal of the site soils that are above the target clean-up
levels. Therefore, the leaching potential of the site soils into the
ground water plume will be eliminated.
No soils will be left at the site that have concentrations above the
clean-up criteria, therefore monitoring of the backfill and remaining
site soils is not necessary. The ground water plume will be
monitored no matter which source control remedial action is
implemented.
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Adequacy and Reliability of Controls
The off-site RCRA incineration and landfill facility should operate
within its permit(s) requirements and comply with all applicable
regulations. Monitoring programs required at RCRA landfills are
designed to detect potential failures so that the necessary actions
would be implemented to control the treatment residuals.
8.10.4 Reduction of Toxicity. Mobility, or Volume
Implementation of this alternative would reduce the toxicity,
mobility, and volume of the contaminants present in the site soils.
This reduction of toxicity, mobility, and volume is accomplished by
the thermal destruction of organic contaminants.
8.10.5 Implementability
Technical Feasibility
Excavation and transportation of contaminated soils are common
construction activities, and are considered technically feasible.
The removal and transport of the contaminated soils is limited by the
excavation rate and/or the rate at which the materials can be
accepted at the RCRA incineration facility. RCRA hazardous waste
requirements must be complied with for all wastes transported
off-site.
The RCRA incinerator would be effective at destroying the organic
compounds present in the soils. The landfill would reliably isolate
the treated soils.
Administrative Feasibility
Implementation of this alternative may require coordination with
municipalities to determine the appropriate transportation routes.
Numerous remedial action contractors and hazardous waste transporters
are available for the excavation and transportation of the site
soils. Coordination and advanced planning is required to ensure that
capacity is available at a RCRA incineration facility.
8.10.6 Compliance with ARARs
Chemical Specific ARARs
This alternative is expected to meet the calculated clean-up criteria
for soils. The site soils above the cleanup criteria would be
excavated and treated at a RCRA incineration facility.
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Action Specific ARARs
Action specific ARARs for this alternative apply to the excavation of
contaminated soils, monitoring requirements, and transportation,
treatment and disposal requirements.
Workers and worker activities that would occur during the
implementation of this alternative must comply with the OSHA
requirements for training, safety, equipment and procedures,
monitoring, recordkeeping and reporting. Also, the RCRA requirements
for preparedness and prevention, contingency plans, and emergency
procedures would apply to this alternative. Compliance with the
above mentioned ARARs would be achieved by following an EPA approved
work plan and a site-specific health and safety plan.
The action specific ARARs associated with the incineration and
disposal of treated soils at a RCRA facility include the RCRA
Standards for Owners/Operators of Permitted Hazardous Waste
Facilities (40 CFR 264), the air emission standards contained in 40
CFR 60, and the Prevention of Significant Deterioration provisions of
the Clean Air Act. A permitted RCRA incineration and disposal
facility must comply with these action specific ARARs.
The RCRA and U.S. Department of Transportation requirements for the
packaging and transportation of hazardous waste would be applicable
to this alternative. Compliance with these ARARs would be achieved
by utilizing a licensed hazardous waste transporter.
8.10.7 Overall Protection of Human Health and the Environment
The excavation of the site soils and subsequent incineration and
disposal of the treated soils at a RCRA facility would meet the soil
remedial action objectives. The toxicity, mobility and volume of the
soil contaminants would be reduced. Protection of human health and
the environment would be achieved by complying with the identified
ARARs for this alternative.
8.10.8 Cost
The capital cost associated with this alternative include site
preparation and restoration and the cost of soil excavation,
transportation and incineration. Because of the relatively short
implementation period associated with this alternative/ operational
and maintenance costs are incorporated in the capital cost.
Therefore, a present worth analysis has not been performed for this
alternative. The estimated cost of this alternative (based on 45,000
cubic yards of soil) is $100,100,000.00. A detailed breakdown of the
estimated cost associated with this alternative are presented in the
final draft Feasibility Study Report.
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9.0 SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES
Overall Protection of Human Health and the Environment
Groundwater Treatment
/
Both air stripping (with carbon adsorption) of extracted
groundwater and carbon adsorption of extracted groundwater would
decrease the potential threat to current and future users of
contaminated ground water at the site or downgradient of the
site. Both alternatives would be implemented until ARAJRs are
met in the aquifer. In addition, effluent from the treatment
system will meet the appropriate criteria for the chosen
discharge alternative.
Discharge Alternatives
/
All of the discharge alternatives considered would protect human
health and the environment with the exception of discharging the
effluent to Myers Creek. Preliminary estimates' of the volume of
water to be discharged indicate the sensitive wetlands
surrounding Myers Creek would be flooded due to the discharge.
This flooding would destroy the wetlands and perhaps cause other
damage as well. In light of this, discharge to Myers Creek has
been eliminated as an option.
Source Treatment
The goal at the site is to protect ground water at the site from
further degradation from the source and thereby diminish the
time required to remediate the contaminated aquifer.
Incineration of the source, on or off-site, and excavation with
off-site disposal would provide the best overall protection of
human health and the environment at this site. On-site thermal
desorption will meet the cleanup goals established for the site
and will allow for the treatment of any residual contamination
through solidification of the treated soil. In-situ soil vacuum
extraction has shown great potential as an effective remediation
technique for soils contaminated with organic compounds. While
it is unknown whether or not cleanup criteria for semivolatile
organic compounds can be met, it is very probable that this
technique may achieve all the cleanup criteria established for
the soil contamination at the site. Overall, incineration would
provide the most protection for human health and the
environment, however, all of the alternatives will have the
potential to meet the cleanup criteria for the contaminants
identified for cleanup.
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Compliance with ARARs
Groundwater Treatment and Discharge, Source Treatment
No alternative requires a separate ARAR waiver. All
alternatives requiring excavation and treatment may require a
"Soil and Debris Treatibility Variance for Remedial Actions".
EPA regulations provide that treatability variances may be
issued on a site-specific basis. 40 CFR 268.44(h). Thus, they
may be approved simultaneously with the selection of a remedy in
a CERCLA response action in the ROD. All other remedial
alternatives (excluding no-action) are expected to meet ARARs.
Long-term effectiveness and permanence
Ground water treatment and discharge
Carbon adsorption and air stripping both provide long-term
effectiveness and permanent solutions for ground water
treatment.
Long-term effectiveness of the discharged treated water is best
provided by reinjection or spray irrigation back into the
wetlands area. This would minimize the impact on the wetlands
over the long term.
Source treatment
Soil vacuum extraction provides for removal of the volatile
fraction of the contaminants in soil. The long-term
effectiveness is unknown, however, it has been established that
soil vacuum extraction removes large quantities of contaminants
and would therefore provide a permanent solution. Thermal
desorption provides for long-term effectiveness and permanence
since the organic contaminants are removed from the soil and, if
necessary, remaining contaminants are solidified. On-site
incineration or excavation and off-site treatment/disposal would
also provide long-term effectiveness and permanence.
Reduction of mobility, toxicitv. or volume
Air stripping increases the mobility of the contaminants after
their extraction, allowing it to be captured through the carbon
adsorption phase of treatment and as part of the emission
controls. Carbon adsorption reduces the mobility of
contaminants by capturing it in the treatment process.
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Source treatment
Incineration destroys the contaminants, thereby eliminating
toxicity and mobility, and reducing volume. Soil vacuum
extraction and thermal desorption do not affect toxicity in and
of themselves, however the treatment of the removed contaminants
effectively destroy the contaminants. They both increase
mobility by transferring contaminants to the air, thereby
reducing their volume in the soil. Mobility of the contaminants
in air for all the alternatives can be controlled by requiring
strict emission control procedures as part of the remedy.
Off-site disposal of wastes does not affect the inherent
toxicity, mobility, or volume of the waste.
Short-term effectiveness
Ground water treatment and discharge
Both air stripping and carbon adsorption may have the following
short-term effects:
risks to workers from exposure to drilling fluids and soil
during the installation of the ground water extraction
wells.
risks to workers and environment from release of
contaminated water because of accidental spillage.
risks to workers, environment and nearby members of the
public from uncontrolled emissions.
The Remedial Design will include all necessary measures to
minimize potential adverse short-term effects on public health
or the environment.
Source treatment
All alternatives with the exception of in-situ soil vacuum
extraction require excavation of contaminated soils and have
short-term impacts on the environment due to the release of
organic contaminants (VOCs) into the air. Soil vacuum
extraction, thermal desorption and incineration may have
short-term impacts due to emissions from the various systems.
Off-site disposal of contaminated soils or off-site incineration
of these wastes involve transportation of the waste, increasing
short-term risk to populations along the transport route.
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Implementability
Groundwater treatment and discharge
Air stripping and carbon adsorption are both proven
technologies. Treatment systems and vendors are readily
available and no impediment to implementation of either
alternative is foreseen.
Discharge to the Congaree river, two to three miles away, would
be difficult to achieve and to maintain over the time estimated
to complete the groundwater treatment. Spray irrigation and
injection into the subsurface are both implementable at the
site.
Source Treatment
Soil vacuum extraction is a relatively new technology, but it is
expected to be fully implementable. This technology is expected
to be the most easily implemented due to a minimal necessity for
intrusive activities. Additionally, very few materials handling
difficulties are anticipated. Incineration is a proven
technology. On-site incineration often invokes a negative
reaction from local citizens. On-site thermal desorption and
incineration are subject to substantive but not to
administrative requirements, and are fully implementable.
Excavation and off-site incineration may be difficult to
J implement due to availability of incinerator capacity in South
Carolina. Off-site disposal of the contaminated soil is
implementable.
Cost-Effectiveness
In-situ soil vacuum extraction is the most cost-effective
remedy. All cost estimates for remedies involving excavation in
the Feasibility Study Report are based on an estimated 45,000
cubic yards of soil to be remediated. This estimate is very
high. An independent calculation of the volume of soil
contaminated at concentrations greater than the cleanup criteria
resulted in an estimate of approximately 23,000 cubic yards.
This independent estimate was prepared by RAI, the EPA oversight
contractor. The actual costs for all remedies requiring
excavation and treatment would be lower than given in the
Feasibility Study for less volume. Detailed estimated costs
(based on 45,000 cubic yards of soil) are as follows:
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Groundwater treatment
No Action Alternative $ .76M
Carbon Adsorption $ 16.10M
Air Stripping $ 4.34M
Discharge Alternatives
Subsurface Infiltration $ .16M
Myers Creek $ .42M
Surface Irrigation $ .45M
Congaree River Discharge $ 3.32M
Source Treatments
In-situ Soil Vacuum Extraction $ 1.07M
On-site incineration with $ 28.26M
stabilization of treated soils
On-site thermal desorption with $ 18.25M
stabilization of treated soils
Off-site Disposal of contaminated $ 20.70M
soils
Off-site Thermal Treatment of $100.10M
contaminated soils
The Carbon Adsorption alternative provides the same benefit as
the Air Stripping alternative yet costs a great deal more.
Therefore, the Air Stripping Alternative is the most
cost-effective alternative for treatment of the contaminated
groundwater at the site.
Reinjection of groundwater is the least expensive of the
discharge alternatives. This alternative will also help
mitigate any potential impacts to the surrounding wetlands.
Subsurface injection of the treated water is a cost-effective
alternative.
Soil vacuum extraction is the most cost-effective alternative,
assuming all ARARs can be met. The benefits provided by the
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other alternatives as compared to this in-situ alternative do
not justify additional expenditure. The in-situ soil vacuum
extraction alternative is more cost-effective than the other
alternatives primarily because it provides an equal benefit for
less cost. Long-term effectiveness, permanence, and
protectiveness are achieved, and reduction of toxicity, mobility
and volume is achieved.
State Acceptance
The State of South Carolina has indicated verbally that they
concur with the selected remedy. All the excavation and
treatment alternatives are acceptable to the State if they
include treatment of residual metals contamination. The State
has stipulated that they will not concur with a ROD unless given
assurances that an additional groundwater investigation is
conducted. Additional groundwater studies, including the
installation of a minimum of two deep wells, will be necessary
during the Remedial Design development to further define the
contamination.
Community Acceptance
The public meeting was well-attended. Local citizens voiced
concerns over the Agency's timetable and urged rapid action at
the site. Written comments were received from the Bluff Road
Group, representatives of a local citizen's group and from the
South Carolina Department of Health and Environmental Control.
The latter comments are described under "State Acceptance". The
private citizens voiced a preference for off-site incineration.
It is likely the Agency's chosen alternative will be readily
accepted by the public. A more detailed response to all
comments received during the public comment period is provided
in the responsiveness summary.
10.0 SELECTED REMEDY
The remedy selected for this site is:
extraction and on-site treatment by air stripping of
contaminated ground water at the site
in-situ soil vacuum extraction of contaminated soils at the
site
monitoring
subsurface injection of treated water
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This remedy will attain a 10~° cancer risk level as it removes
the source of the groundwater contamination as well as the
contaminated groundwater.
10.1 Description of Recommended Alternative
Groundwater treatment and discharge
This alternative consists of a combination of ground water
extraction and ground water treatment. Contaminated ground
water would be extracted from the upper aquifer by installing
recovery wells. Ground water treatment would be accomplished by
means of air stripping towers, followed by a granular activated
carbon (GAC) system. The more volatile constituents in ground
water would be removed by air stripping, while semi-volatiles
would be removed by the GAC system. A pretreatment process,
such as precipitation or flocculation, may be necessary to
remove metals from the ground water prior to treatment by air
stripping and GAC. The need for any such pretreatment process
would be evaluated as part of the remedial design activities.
The ground water extraction system would consist of a
combination of recovery wells located within the contaminant
plume, and at the periphery of the plume. Recovery wells would
be placed in the more highly contaminated zone of the plume to
facilitate rapid removal of organics. The periphery wells would
be used to limit expansion of the plume.
The extraction system including number, location, and
configuration of wells would be developed during the remedial
design. Pump tests and ground water modeling would be required
for the design of the extraction system. For the purpose of
this analysis, four extraction wells and a total flow of 100 gpm
were used. The pumping rate is a conservative value based on
data from the RI.
The ground water from the extraction wells would be pumped into
a surge tank before it is fed to the air stripping system. The
air stripping system would consist of two towers arranged in
series. Both towers would have 12 feet of packing material, 30
inches in diameter and use high air-to-water ratios.
Prior to treatment, the extracted ground water would contain the
compounds identified in Tables 1 and 2 at the measured maximum
concentration shown in column 1. Contaminant concentrations
should steadily decrease from these levels. Actual treatment
system influent composition would be defined during remedial
design.
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Air stripping can effectively remove most of the contaminants
found in ground water at the Bluff Road Site (Golder, 1986).
The exceptions would be 2-chlorophenol and phenols which would
be removed by adsorption on the GAC.
After air stripping, the ground water would be pumped through
cartridge filters and two carbon beds, also arranged in series.
When the carbon in the first bed is spent, it would be
replaced. A valve on the adsorption system would then be
switched to reverse the order of the beds in the series. The
beds are sized so that carbon would be expected to be replaced
every 4 to 6 weeks. The system would be automated and designed
for unattended operation. The final design of the ground water
extraction system, air stripper, and GAC systems would require
additional data collection prior to design.
As a result of ground water extraction and treatment, a
discharge stream of treated ground water would be generated. As
a best engineering judgement based on available data, the
volumetric flow of the discharge stream is assumed to be 144,000
gallons per day based on 100 gpm ground water recovery system
operating 24 hours per day. More precise ground water
withdrawal and discharge values would be determined as part of
the remedial design.
Infiltration galleries are a proven and viable alternative for
effluent discharge. The process involves the use of drains,
trenches and/or piping to introduce the treated ground water
into the vadose zone where it is allowed to percolate into the
soil. There are two basic types of infiltration galleries,
horizontal and vertical. The horizontal system uses trenches
lined with gravel or perforated piping to introduce the ground
water into the vadose zone. Vertical infiltration uses vertical
perforated piping with appropriate packing materials to allow
radial infiltration over the depth of the vadose zone.
Discharge limitations for subsurface infiltration of the treated
ground water will be the cleanup criteria. This effluent
discharge option would establish the discharge design
requirements for the ground water treatment system.
The effectiveness of this method is dependent on vadose zone
acceptance of the treated water. A preliminary assessment of
infiltration rates based on aquifer and near aquifer vadose zone
soil classification indicates that this technology would be
feasible for the Bluff Road Site.
Percolation testing must be performed to determine permissible
application rates of treated ground water and to establish the
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most appropriate process alternative (i.e., horizontal or
vertical). The infiltration gallery must be located so that
recharge to the aquifer does not interfere with the performance
of the extraction system (hydraulic control). These
considerations can be addressed adequately in design. The basis
for conceptual cost evaluation is a horizontal infiltration
gallery. The estimated infiltration area required was
determined using the lowest permeability determined by
performing slug tests on shallow wells in the upper aquifer
(9.27 X 10 cm/sec). This equates to an estimated
permissible application rate of 50 gallons/day/ft2. With an
estimated flow rate of 100 gpm, approximately 3000 ft. of
infiltration trenches would be required for horizontal
infiltration. The infiltration trenches would be distributed
over an area of approximately 15/000 square feet. This is based
on a trench width of approximately 2 feet and trench spacing of
approximately 7.5 feet (center to center). Again, permissible
application rates would have to be confirmed during remedial
design.
Source Remediation
The vacuum extraction system would consist of air vacuum wells
installed in the unsaturated zone. A pump and manifold system
of PVC pipes will be used for applying a vacuum on the air wells
which feed an in-line water removal system, and an in-line vapor
phase carbon adsorption system for VOC removal. Once the well
system has been installed and the vacuum becomes fully
established in the soil column, VOCs are drawn out of the soil
and through the vacuum wells. This treatment technology has
been proven effective at treating soils that contain elevated
levels of organic contaminants. Prior to initiation of this
remedial alternative, supplementary soil sampling would be
performed to adequately delineate the aerial extent of the
necessary vacuum influence areas.
Process Description
Soil vacuum extraction as proposed herein is an in-situ
treatment process used to clean up soils that contain volatile
and some semi-volatile organic compounds. The process utilizes
extraction wells to induce a vacuum on subsurface soils. The
subsurface vacuum propagates laterally, causing in-situ
volatilization of compounds that are adsorbed to soils.
Vaporized compounds and subsurface air migrate rapidly to
extraction wells, essentially air stripping the soils in-place.
A vacuum extraction system consists of a network of air
withdrawal (or vacuum) wells installed in the unsaturated zone.
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A pump and manifold system of PVC pipes is used for applying a
vacuum on the air wells which feed an in-line water removal
system, and an in-line vapor phase carbon adsorption system for
VOC removal. Vacuum wells can be installed vertically to the
full depth of the contaminated unsaturated zone. Vertical wells
were selected due to the depth of the soil strata requiring
remediation, geotechnical conditions, and the depth to
groundwater.
Once the well system has been installed and the vacuum becomes
fully established in the soil column, VOCs would be drawn out of
the soil and through the vacuum wells. In all soil vacuum
extraction operations, the daily VOC removal rates eventually
decrease as volatiles are recovered from the soil. This occurs
since volatile recovery decreases the VOC concentration in the
soil, and consequently reduces the diffusion rate of volatiles
from the soil. Volatiles in the air stream are removed by the
carbon adsorption system or destroyed by fume incineration,
after which the cleaned air is discharged to the atmosphere.
The application of soil vacuum extraction to the unsaturated
zone remediation is a multi-step process. Specifically,
full-scale vacuum extraction systems are designed with the aid
of laboratory and pilot-scale VOC stripping tests. Further
testing would be performed as part of remedial design.
10.2 Cost of Recommended Alternative
5
Groundwater Treatment and discharge
The present worth cost of the Air Stripping alternative would be
approximately $4,339,500. This cost would include a capital
cost of $1,012,000 for construction of The groundwater
extraction system, the treatment units, a treated water
discharge system, and all associated piping. This cost also
includes annual expenditures for operation and upkeep of the
system of $306,875. The total of the annual costs over 16
years, using a 5% discount rate is $3,326,500.
The present worth cost of the infiltration gallery/reinjection
discharge alternative is approximately $165,484.
The estimated total cost for the soil vacuum extraction system
with vapor phase carbon adsorption would be approximately
$1,070,000. This capital cost includes the anticipated O&M
expenditures since this remedial action is not expected to last
over 2 years.
Capital cost would include construction of the soil vapor
extraction system, vapor treatment system, and all associated
piping/mechanical facilities.
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The total present worth cost for the remedial action is $5,574,984
based on the information in the Feasibility Study Report. A detailed
cost breakdown for each alternative and the selected remedy is given
in the tables at the end of. Chapter 5 in the Feasibility Study
Report.
10.3 Schedule
The Remedial Design is to begin in the winter/spring of 1991 and be
completed no later than one year later. Construction of the Remedial
Action should begin in January 1992.
10.4 Future Actions
After groundwater remediation shutdown, a post closure groundwater
monitoring program is to be initiated to determine the permanence of
remediation. No other remedial actions, other than those described
herein, are anticipated in the future at this site. The selected
remedy addresses all known areas of contamination at the site.
11.0 STATUTORY DETERMINATIONS
The selected remedy satisfies the requirements of Section 121 of
CERCLA.
Protection of Human Health and the Environment
The selected remedy will permanently treat the groundwater and soil
and removes or minimizes the potential risks associated with the
wastes. Dermal, ingestion, and inhalation contact with site
contaminants would be eliminated, and risks posed by continued
groundwater contamination would be reduced.
Attainment of ARARs
This alternative will comply with ARARs.
This alternative will comply with the substantive technical
requirements of the Clean Air Act 40 CFR Part 50 concerning
particulates and volatile organic emissions during excavation.
Cost-Effectiveness
The groundwater and source remediation technologies are more
cost-effective than the other alternatives considered primarily
because they provide greater benefit for the cost.
Utilization of Permanent Solutions and Alternative Treatment
Technologies or Resource Recovery Technologies to the Maximum Extent
Practicable
The recommended alternative represents the maximum extent to which
permanent solutions and treatment can be practicably utilized for
this action.
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Preference for Treatment as a Principal Element
The preference for treatment is satisfied by the use of a vacuum
extraction system to remove contamination from soil at the site and
the use of air stripping to treat contaminated ground water at the
site. The principal threats at the site will be mitigated by use of
these treatment technologies.
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RESPONSIVENESS SUMMARY
SCRDI BLUFF ROAD SITE
This community relations responsiveness summary is divided into
the following sections:
Overviewt This section discusses EPA's preferred
alternatives for remedial action.
Background; This section provides a brief history of
community interest and concerns raised during
remedial planning at the SCRDI Bluff Road Site.
Part I; This section provides a summary of commentor's
major issues and concerns, and expressly
acknowledges and responds to those raised by the
local community. "Local community" may include
local home owners, businesses, the municipality,
and not infrequently, potentially responsible
parties (PRPs).
Part lit This section provides a comprehensive response to
all significant comments and is comprised
primarily of the specific legal and technical
questions raised during the public comment
period. If necessary, this section will
elaborate with technical detail on answers
covered in Part I.
Any points of conflict or ambiguity between information provided
in Parts I and II of this responsiveness summary will be
resolved in favor of the detailed technical presentation
contained in Part II.
OVERVIEW
EPA published its Proposed Plan in April, 1990 and presented its
preferred treatment alternatives for the SCRDI Bluff Road Site,
located in Richland County, South Carolina on April 10, 1990.
EPA's recommended alternatives addressed soil and ground-water
contamination by proposing a ground-water collection and air
stripping treatment combined with a soil extraction and thermal
treatment method. Each recommended .alternative is briefly
described below.
EPA's preferred alternative for addressing ground-water
contamination involves extracting or removing contaminated water
from the upper aquifer using wells and treating the contaminated
water by air stripping. Air stripping is a process by which air
is forced through contaminated water, causing volatile organic
compounds to evaporate. Organic compounds would be treated with
a carbon adsorption treatment, which uses granular activated
carbon to remove organic contaminants found in the water. Once
this process is completed, extracted ground water would be
reinjected into the ground.
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EPA's recommended alternative for treating soil contamination
that was presented to the public involved excavating the site
soils and treating the soils on-site using low temperature
thermal desorption. This treatment method allows moisture and
organic compounds to vaporize and escape from the soil. Once
this process is completed, the soil would be discharged into a
mill where water would be added to it to reduce dusting
problems. The treated soil would then be returned to the site.
The community in general prefers the removal of contaminants to
a disposal facility off-site. There were no specific complaints
directed toward the preferred treatment for groundwater since
the residents are concerned about the impact of the contaminated
aquifer on local wells. PRPs disagreed with the preferred
alternative for treatment of soils, citing a less costly soil
treatment alternative, in-situ soil venting, as their
preference. The State enforcement agency, SCDHEC, is in
agreement with EPA's preferred choice for soils and groundwater,
but disagreed with cleanup criteria proposed for soils.
The alternative presented in the Record of Decision for treating
soil contamination is soil vacuum extraction. This change was
based on the results of a pilot test conducted at the site which
demonstrated that the contaminants in soils can be removed by
soil vacuum extraction.
BACKGROUND
EPA's most recent community relations efforts included an
availability session held in November 1989 to present the
remedial investigation study results? release of a fact sheet
detailing cleanup options in April 1990; and, a public meeting
that was held on April 10, 1990. Approximately 60 people
attended the public meeting.
Site information repositories contain the RI/FS Report and other
relevant documents. EPA maintained contact with local officials
and citizens throughout the remedy selection process.
EPA opened a public comment period from April 10 through June
10, 1990. The public comment period, originally scheduled to
end May 10, 1990, was extended by one month.
Community interest and concern about the site has been
relatively high over the past several years. The Hopkins
Community Council and Citizens for Hopkins are extremely
concerned about ground- and drinking water quality and land
development options when remediation is complete. EPA agreed to
expand its sampling plan to include wells identified by
residents. Two additional attendees were told that EPA
anticipates the cleanup will take approximately 16 years to
complete. No projection on restricted use can be made now.
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PART I: SUMMARY OF COMMENTORS' MAJOR ISSUES AND CONCERNS
This section provides a summary of major issues and concerns
raised during the public comment period on the RI/FS and
Proposed Plan, and identifies how EPA addressed their concerns.
The issues and concerns are divided into five categories:
A. Implementation of Remedy
B. Health Concerns
C. Remedy Selection
D. Site History
E. The Concerns
A. Implementation of Remedy
o A citizen asked if EPA's proposed soil and
ground-water contamination remedies have been
implemented elsewhere.
o EPA Response. Yes. Air stripping of treated
ground water is used by EPA at many sites and is
a proven technology. Thermal desorption is a
newer treatment method. It has been used
successfully in an EPA Region in the Northeast,
and will be implemented at a site in South
Carolina.
o A meeting attendee asked what percentage of the
contaminants will be removed under EPA's proposed
cleanup plan.
EPA Response. EPA cannot provide a specific
percentage of contaminants that will be removed
under the proposed plan. The feasibility study
lists cleanup goals and actual numbers associated
with the goals. Under the proposed plan, EPA
will clean up ground water to the maximum safe
concentrations of certain compounds, or the
maximum contaminant levels. . These levels are
specified in the Safe Drinking Water Act.
o An attendee asked if under the proposed plan, any
contamination would remain at the site after EPA
has completed treatment of ground water and soil.
o The State of South Carolina requested that soils
be cleaned to background levels indicating that
Applicable, Relevant and Appropriate Requirements
(ARARs) in the State of South Carolina mandate
same.
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EPA Response. EPA requested that the State
enforcement agency submit or cite to EPA
representatives regulations or laws it determined
were ARARs at the Site. EPA representatives met
with State officials on June 5, 1990 and
expressed that soils are perceived as a threat to
groundwater in that leaching of residual
contaminants could affect groundwater quality.
Because EPA must meet Safe Drinking Water
Standards, soils will be cleaned to levels
required for compliance. In some instances, EPA
has cleaned soils below background levels in
order to satisfy applicable standards.
EPA Response. Yes. If, for example, the maximum
contaminant level for a particular chemical is
five parts per billion, then that chemical may be
present at three or four parts per billion after
treatment is completed.
o A citizen asked if the process to clean up
ground-water contamination will take 16 years.
EPA Response. Yes. The feasibility study
estimates that ground-water contamination will
take 16 years to clean up. A better estimate of
the time required to remediate the aquifer will
be available at the conclusion of the remedial
design.
o An attendee asked what type of oversight EPA will
provide during site cleanup.
EPA Response. EPA is responsible for overseeing
site cleanup. The U.S. Army Corps of Engineers
may share oversight responsibility at the Site
given their technical expertise in construction.
If responsible parties perform site cleanup work,
then EPA and a third-party oversight contractor
hired by EPA, oversee the entire project.
Sometimes, the Corps of Engineers also provides
oversight at responsible party lead sites.
o .An attendee asked if EPA will monitor the site
once cleanup is -completed.
EPA Response. Yes. EPA will monitor the site
for some time. As part of the remedial action,
an operation and maintenance plan will be
developed and implemented. This plan will
include a monitoring program. At some point,
approximately sixteen years from now when the
contaminated soil and ground water are cleaned
up, EPA will stop monitoring the site.
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B. Health Concerns
A citizen asked if drums are still on the Site,
and if so, do the drums contain contaminated
substances and what will be done to remove them
from the site.
EPA Response. There were no drums remaining at
the Site at the conclusion of the RI field work.
All drums were removed from the Site in 1982. An
above-ground storage tank also was removed as
part of the remedial investigation. Recent well
sampling activities have resulted in drummed
purge water remaining in drums on-site until
results indicate how these drums may disposed of
properly.
The council member for the Lower Richland area
asked if the ground water at the site is
contaminated.
EPA Response. Yes. The ground water at the site
is contaminated.
The council member for the Lower Richland area
asked how far and in what direction the
ground-water contamination has spread.
EPA Response. Ground-water contamination is in
the upper aquifer. The contaminant plume has
moved approximately 1,400 to 1,500 feet
downgradient and has expanded about 1,000 to
1,500 feet in width. It is an extensive plume
that is located within the site boundaries.
Although the ground-water contamination is headed
towards the Myers Creek area, the anticipated
corrective action may allow for the placement of
extraction wells in the plume and at the front
edge of the plume to stop migration downgradient.
The council member for the Lower Richland area
asked how frequently EPA plans to sample the site
monitoring wells to check whether or not the
contaminated ground water is.moving.
EPA Response. EPA will be resampling the wells
the week of April 16th. At this time, there is
no set schedule to sample the wells. The State
of South Carolina is working with EPA, and has
requested that the wells be sampled about every
three or four months. EPA is going to try to do
this. It could be every four months, instead of
three, but EPA will be monitoring the situation.
EPA will ensure that sampling results are
available in the information repository.
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An attendee asked why wells of the residents
located near the contaminated area have not been
tested for contamination.
EPA Response. EPA has not tested any private
wells because sampling of the site monitoring
wells that are located the greatest distance from
the source of the ground-water contamination have
not detected contamination. If EPA found
contamination in these wells, which are located
between the site and places of residence, EPA
would install monitoring wells closer to area
residents and then test for ground-water
contamination.
The council member from the Lower Richland area
asked if EPA would test the well water of
residences closest to the site.
EPA Response. EPA will consider testing the well
water of some area residents when the site wells
are sampled on April 16, 1990. [The residents
were later found to be on a municipal water
supply.]
A local citizens' group, Citizens for Hopkins,
requested that EPA test the well water of
residences located below the dump site along
Myers Creek and south to the river, which
includes many homes along Bluff Road and Old
Bluff Road. The group requested that both
shallow wells and deep wells be tested.
EPA Response. EPA attempted to sample private
wells located downgradient from the Site in April
1990. These wells were determined to be
connected to municipal water supplies, therefore,
no samples were collected.
An attendee asked if contaminated compounds were
migrating from the site into Myers Creek.
EPA Response. .EPA has sampled the sediment and
water in Myers Creek and found some increases in
volatile organic compounds, but not enough
increase to pose a threat to human health and the
environment.
A citizen asked how many people will develop
cancer in the 16-year period that EPA estimates
will be necessary to complete ground-water
treatment.
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EPA Response. No one is currently exposed to the
ground-water contamination because no one is
pumping and using the contaminated water. Also,
no one will be exposed during the estimated
16-year cleanup period, because wells will be
installed to pump and treat the contaminated
ground water and to stop the contaminated plume
from migrating.
A citizen asked if it is safe for children and
adults to fish at Myers Creek and surrounding
streams.
EPA Response. Yes. Based on the results of
EPA's sampling, contamination from the Site does
not pose a threat to human health in Myers
Creek. If there are concerns regarding the
pollution of Myers Creek from other sources, EPA
recommends that these concerns be presented to
the South Carolina Department of Health and
Environmental Control (SCDHEC).
SCDHEC asked that EPA conduct ground-water
sampling on a quarterly basis during the remedial
design phase and on a semiannual basis during the
remedial action phase.
EPA Response. This request from SCDHEC has been
received and is to be included as part of the
work to be performed during the remedial design
and remedial action at the site.
C. Remedy Selection
SCDHEC indicated commented that all remedies
selected at the Bluff Road site must comply with
South Carolina State laws and requirements.
EPA Response. CERCLA requires that remedial
actions shall at least attain Federal or more
stringent State standards, requirements,
criteria, or limitations that are legally
applicable or relevant and appropriate
requirements under the circumstances of the
release of the hazardous substances.
Citizens for Hopkins and the Hopkins Community
Council requested that EPA implement Alternative
9, Soil Excavation and Off-Site Thermal
Treatment, rather than Alternative 7, Thermal
Desorption.
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EPA Response. Thermal desorption, combined with
air stripping to address contaminated ground
water, provides the best balance among the nine
criteria that EPA uses to evaluate remedial
alternatives. EPA did not choose Alternative 9,
Soil Excavation and Off-Site Thermal Treatment,
because this remedy is not cost effective when
compared to other soil treatment alternatives.
[Since the public meeting a treatability study
was conducted at the site to determine if soil
vacuum extraction would extract the semi-volatile
compounds present in the soil. This treatment
does appear to remove the semi-volatile compounds
therefore it would best meet the nine criteria.]
A group of PRPs commented that the risk analyses
conducted to assess soil contamination
demonstrated that the soils are not an
endangerment to public health or the
environment. The PRPs asked EPA to select the
least costly remedy, in-situ soil venting, rather
than EPA's proposed alternative, thermal
desorption.
EPA Response. After careful review of all soil
treatment alternatives, EPA determined that
Alternative 7, Thermal Desorption, provides the
best balance among the nine criteria that EPA
uses to evaluate remedial alternatives.
[EPA has since decided that soil vacuum
extraction (soil venting) provides the best
balance of the nine criteria after demonstrations
at the Site resulted in extraction of soil
contaminants.]
D. Site History
An attendee asked when waste disposal activities
at the Site ended.
EPA Response. Activity at the site ended in 1981
or 1982. In 1982, all of the barrels and much of
the contaminated surface soil were removed from
the site during a removal action.
An attendee who observed numerous barrels on the
site about one year ago asked what happened to
the barrels and why they were there.
EPA Response. The barrels contained water
extracted from Site monitoring wells. In order
to sample ground water for contamination, a
certain amount of water must first be purged from
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the well. Because it was not known whether the
water was contaminated or uncontaminated, the
water was collected and stored in barrels. When
sampling was completed, the water from the
barrels was pumped into a tank and taken off-site
for disposal. The empty drums were picked up by
the contractor and removed from the site for
recycling.
An attendee wanted to know why an area on the
Site containing numerous barrels used for
ground-water sampling was excavated.
EPA Response. The area was not excavated, but
rather a road was put in to provide access to the
location where a monitoring well was to be
installed.
A citizen asked where the chemicals came from
that contaminated the Site.
EPA Response. The chemicals came from a
recycling and disposal operation that was run by
a company called South Carolina Recycling and
Disposal which collected materials in the
southeast and other areas of the country.
E. Other Concerns
The council member for the Lower Richland area
asked to receive a copy of the ground-water
sampling results that EPA agreed to provide in
the information repository.
EPA Response. Yes. EPA will send the council
member a copy of the ground-water sampling
results obtained at the site.
A citizen of Hopkins asked if EPA would make a
change in the fact sheet to state that the
residents of Hopkins use well water.
EPA Response. Yes. If confirmed, EPA will make
the change.
An attendee asked what EPA will do in the event
that Site cleanup exceeds EPA's estimated cost.
EPA Response. EPA is planning to work with the
responsible parties and have them do the work.
If the cost of cleanup under the proposed plan
exceeds the estimate, responsible parties will be
assessed the additional costs. If the cleanup is
financed with government funds, the costs will be
recovered from responsible parties.
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A citizen asked if the responsible parties have
agreed to pay 52 percent of the cost of site
cleanup and if EPA has agreed to pay the
remainder.
EPA Response. No. The figure 52 percent refers
to a group of responsible parties that
voluntarily agreed to do the work recently
undertaken at the Site. Other responsible
parties include a group of federal facilities
that will take care of their share of the
cleanup, a group of responsible parties that EPA
sued in 1982, and others who have not
participated in any activities at the Site. EPA
hopes that this project will be completely funded
by responsible parties. If that does not happen,
the unreimbursed cost of cleanup will be
recovered by EPA.
A citizen asked if the community will have input
into the selection of the cleanup process that
will be implemented at the site.
EPA Response. Yes. The public will have thirty
days to respond to EPA's proposed cleanup plan.
The public comment period begins on April 10,
1990, the date of the public meeting. The
information repository contains detailed
documents to assist the public in commenting on
EPA's proposed plan. All public comments will be
considered before EPA makes a decision on the
cleanup plan that will be implemented.
An attendee asked if comments from the Community
Council could be submitted in a unified version
along with the signatures of persons who agree to
a particular cleanup action.
EPA Response. Yes. The Council's comments can
be submitted in a unified version, accompanied by
signatures of people who support a particular
cleanup plan.
A citizen asked where the Site is ranked
nationally and at the State level.
EPA Response. The Site is ranked first on South
Carolina's cleanup priority list. It is ranked
number 83 on the National Priorities List.
A citizen asked if use of the Site will be
restricted after treatment of contaminated soil
and ground water is completed.
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EPA Response. When response activities are
concluded, EPA anticipates the Site will not pose
a threat to human health and the environment.
EPA cannot say wether restrictions on land use
will be necessary at that time.
PART II: COMPREHENSIVE RESPONSE TO SIGNIFICANT COMMENTS
This section provides a comprehensive response to all
significant comments on the SCRDI Bluff Road Site received at
the public meeting held April 10, 1990, and during the public
comment period. Some of the information presented in this
section elaborates with technical detail on answers covered in
Part I of this responsiveness summary. Concerns and questions
presented in this section can be grouped in four categories:
A. Implementation of Remedy
B. Health Concerns
C. Remedy Selection
D. Miscellaneous.
A summary of the comments and EPA's response to them is provided
below.
A. Implementation of Remedy
o An attendee asked if ground-water treatment under
EPA's proposed plan will take 16 years to
complete.
EPA Response. Yes. Sixteen years is a rough
estimate. One of the activities EPA undertakes
during the remedial design process is gathering
more data on the extent of contamination.
Extensive modeling is conducted to determine the
exact location at which ground-water extraction
wells should be installed and exactly how the
treatment system should be set up. From these
activities, an estimated time frame for cleanup
is established. Sixteen years is the amount of
time EPA estimated for cleaning up ground-water
contamination at the Bluff Road Site.
o The SCDHEC agreed with EPA's selection of
reinjecting treated ground water as the discharge
alternative, but expressed concern that
reinjection into the vadose zone may present
problems, such as flooding. SCDHEC asked EPA to
conduct a pilot project to test the effect of
reinjecting treated ground water into the vadose
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zone and the aquifer. SCDHEC requested that the
pilot project be completed prior to implementing
the proposed ground-water reinjection
alternative.
EPA Response. EPA agrees pilot testing will be
necessary to determine specific design and
operating procedures to allow for effective
operation of a reinjection system.
The Bluff Road Group commented that thermal
desorption of contaminated soil poses numerous
problems that will likely result in a one- to
two-year delay in implementing the cleanup. For
example, thermal desorption requires excavation,
with the potential for risk to public health and
the environment; requires extensive materials
handling; may necessitate access agreements or
easements for adjacent land; raises potential
wetland issues; and is affected by the
availability of treatment units.
EPA Response; EPA agrees that alternatives
requiring excavation pose problems of their own.
One of the advantages of the soil vacuum
extraction alternative is the minimization of
short term risks to workers and nearby
populations. EPA has since determined that
in-situ soil venting is appropriate. Therefore,
many of these concerns would no longer be
applicable.
The SCDHEC commented that EPA's preferred soil
treatment alternative, on-site thermal
desorption, will not treat inorganic compounds.
SCDHEC suggested that either a pre-treatment or
post-treatment process be implemented, in
addition to thermal desorption, to treat
inorganic and semi-volatile organic compounds.
EPA Response. None of the alternatives
considered for soil remediation directly address
inorganic constituents. : Models used to determine
the maximum allowable concentrations of
contaminants did not identify any inorganic
constituents at concentrations posing a threat to
the groundwater.
The SCDHEC commented that due to the presence of
inorganic and semi-volatile organic compounds at
the Site, soil venting will not be an effective
method for remediating soil contamination.
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EPA Response. Models used to determine the
maximum allowable concentrations of contaminants
did not identify any inorganic constituents at
concentrations posing a threat to the
groundwater. A recent pilot test of the soil
vacuum extraction technology indicates it is
capable of removing semi-volatile organic
compounds.
The SCDHEC requested that EPA conduct additional
investigations of the Site geology and the
horizontal and vertical extent of the
contaminated ground-water plume during the
remedial design phase.
EPA Response. EPA has included provisions for
additional investigative work to be performed as
part of the Record of Decision.
B. Health Concerns
Two attendees expressed concern about migration
of ground-water contamination and asked how often
EPA will sample ground water at the Site.
EPAm Response. After the public meeting, EPA made
provisions for quarterly sampling at the Site
through January 1991. Currently, there is an
array of monitoring wells installed at the Site.
The well that is farthest downgradient from the
source of contamination indicates there is no
contamination at that point. EPA assesses
ground-water contamination by locating the source
of contamination. Once the source has been
located, the direction of ground-water flow is
determined and monitoring wells are then
installed to test for contamination and to track
how far the contamination has spread. This is
the process EPA has followed at the Bluff Road
Site. EPA has found that the contaminated
ground-water plume has spread about 2,200 hundred
feet. EPA.will, continue to sample the wells
until a ground-water,extraction system is
installed.
A citizen expressed concern about off-site
migration of contaminated compounds to Myers
Creek and asked if it is possible that some of
the compounds found on the site, specifically
barium, may be migrating faster than others and
have reached water sources in the area.
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EPA Response. . Some barium was detected at two
Site monitoring wells. Barium is a natural
compound.that is found in geological deposits, as
are many other metals. It is possible that the
metals detected in surface water bodies such as
Myers Creek may be due to runoff. Volatile
organics, which are the primary concern of
ground-water contamination at the Site, are
extremely mobile. EPA has delineated a plume of
volatile organics with high mobility.
A citizen asked for an explanation of what
"maximum contaminant levels" (MCLs) mean.
EPA Response. MCLs are the maximum permissible
levels of contaminants that may be consumed in
drinking water. These levels are determined by
EPA and are applicable to all public water
supplies. For carcinogens, MCLs are based on a
concentration of a carcinogen that would not
increase the risk of one additional case of
cancer per million people for a lifetime exposure
to drinking water. Thus, given EPA's proposed
cleanup level, in a million people there will be
one increase in cancer cases. MCLs are based on
the daily consumption of drinking water for a
lifetime exposure (estimated at 70 years)
relative to the potency of the particular
carcinogen present. For each carcinogen, there
is a different potency based on the carcinogen's
potential for causing cancer.
C. Remedy Selection
Three PRPs commented that EPA's selection of
thermal desorption, rather than in-situ soil
venting, as the preferred remedy for soil
contamination is not cost effective and
therefore, is inconsistent with the National Oil
and Hazardous Substances Pollution Contingency
Plan (NCP). The commentors also noted that the
NCP requires EPA .to.select the least expensive
remedy when all remedies .examined are equally
feasible, reliable, and provide the same level of
protection. The commentors further state that
both EPA's FS Report and Site fact sheet
acknowledge that both remedies satisfy EPA's
criteria for remedy selection, and that the only
difference between the two remedies is cost —
thermal desorption is 17 times more expensive
than in-situ soil venting.
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EPA Response; EPA has reviewed the new data
provided as a "result of the pilot test for soil
vacuum extraction at the Site and now agrees the
above comment is valid and supports the selection
of soil vacuum extraction at the Site.
A group of PRPs commented that in-situ soil
venting, when compared to thermal desorption,
offers advantages other than cost. For example,
in-situ soil venting will minimize air emissions
and avoid community opposition usually voiced
when on-site incineration is a selected remedy.
EPA Responset EPA agrees with this comment.
The Bluff Road Group commented that EPA's
preferred remedy for soil contamination, thermal
desorption, fails to meet NCP requirements with
respect to implementability. For example,
excavation of soils will cause fugitive
emissions, land use requirements may encroach on
wetlands, and thermal treatment equipment is
likely not to be available for at least two
years.
EPA Response; Implementability is defined as
scientific/technical feasibility and availability
of the technology within a reasonable period of
time. Equipment shortages have not been serious
impediments to implementation of alternatives at
other similar sites. Thermal desorption is
implementable at the Bluff Road Site. All of the
items mentioned above are dealt with on a routine
basis at many other sites.
The Bluff Road Group commented that EPA should
choose in-situ soil venting, rather than thermal
desorption, as its preferred remedy to treat soil
contamination because; 1) in-situ soil venting
is an innovative technology that has been
successfully tested and recommended by EPA at
sites with similar geotechnical -and contaminant
conditions; 2) it has greater implementability
with less potential health hazards; and 3) it is
the most cost-effective soil remediation
technology among all the soil remediation
alternatives identified for the Bluff Road site.
EPA Response; EPA disagrees with the first two
points. Each Superfund site is unique, and
requires site specific determinations. However,
results of the pilot test performed at the Site
lead the Agency to believe that soil vacuum
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extraction may. work at this Site. Therefore, EPA
agrees it should be the preferred alternative at
the Site.
A group of PRPs advocating in-situ soil venting
as the selected remedy for soil contamination
suggested that EPA require in the Record of
Decision that a pilot study of this treatment
method be implemented. The pilot study would
address EPA's concerns about unknown site
conditions reducing the effectiveness of this
cleanup method.
EPA Response; EPA requested the Bluff Road Group
to undertake an on-site pilot study of soil
venting/vacuum extraction as part of the RI/FS at
the Site. The Bluff Road Group agreed to this
request, and submitted to EPA on June 6, 1990, a
Work Plan for the pilot study. The pilot test
showed that the identified contaminants of
concern could be extracted by this treatment.
Therefore, the Record of Decision presents soil
vacuum extraction (soil venting) as the preferred
alternative.
E. Other Concerns
The Bluff Road Group commented that vendors who
responded to EPA's Request for Quotation for
implementing the in-situ and thermal desorption
treatment methods did not base their cost
estimates on uniform specifications. For
example, thermal desorption quotations did not
include costs for design, mobilization,
excavation, materials handling,
sampling/analysis, and fill/grading. As a
result, thermal desorption costs are incomplete
and cannot be used as total project costs.
EPA Response; EPA obtained independent cost
estimates due to questions about the actual
quantities of soil to be remediated and a desire
to independently.research remediation costs
estimated by a number of- vendors as opposed to
the singular cost estimate provided by the PRPs
in the Feasibility Study. These independent
estimates indicate costs for some alternatives
were high, however, they also confirmed soil
vacuum extraction to be among the least expensive
alternatives considered.
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