United States Office of
Environmental Protection Emergency and
Agency Remedial Response
EPA/ROD/R04-91/091
September 1991
Superfund
Record of Decision
Ciba-Geigy, AL
-------
REPORT DOCUMENTA 1l0N 11. REPORTNO. I ~ 3. A8cip18nt'8 ~ No.
PAGE EPA/ROD/R04-91/091
4. TI88 and ~ 5. A8part D81e
SUPERFUND RECORD OF DECISION 09130/91
Ciba-Geigy, AL I.
Second Remedial Action
7. AuIIor(8) 8. Performing Organb81lon ~ No.
t. Performing Org8lnlz81l0n Name and Add.... 10. ProjectlTulllWcn UnI1 No.
11. ConIraC1(C) or Gr8nI(G) No.
(C)
(G)
1~ SponaorIng OrganIzatIon Name and Addre88 13. Tn- of Rapor1& P81tod Cowred
U.S. Environmental Protection Agency 8001000
401 M Street, S.W.
Washington, D.C. 20460 14.
15. SUppIamanIary No....
16. Ab81r8e1 (LJm1: 200 wonIa)
The 1,SOO-acre Ciba-Geigy site is an active chemical manufacturer in an industrial
area in McIntosh, Washington County, Alabama. A wetlands area borders the site
property, and part of the site lies within the floodplain of the Tornbigbee River.
From 19S2 to present, Ciba-Geigy, formerly Geigy Chemical Corporation, has produced
various chemicals including DOT, laundry products, he rbicides, insecticides,
agricultural chelating agents, sequestering agents, plastic resins and additives,
antioxidants, and specialty chemicals. In 1982, during an investigation of an
adjacent chemical company, EPA identified onsite contamination in a drinking water
well on the Ciba-Geigy property. In 1985, EPA issued a RCRA permit that included a
corrective action plan requiring Ciba-Geigy to remove and treat ground water and
surface water contamination at the site. EPA performed further investigations to
determine the extent of contamination, and revealed 11 areas of waste management and
potential contamination. These areas contain a variety of waste, debris, and
pesticide by-products and residues. In 1987, as part of the corrective action plan
requirements, Ciba-Geigy installed an additional wastewater treatment system and
ground water monitoring wells. A 1989 Record of Decision (ROD) provided for
(See Attached Page)
17. Doa8nenI Analyaia .. DHcripto..
Record of Decision - Ciba-Geigy, AL
Second Remedial Action
Contaminated Media: soil, sludge, debris
Key Contaminants: VOCs (benzene, toluene), other organics (PCBs, pesticides), metals
b. Idenlifier8l~ Terma (lead)
c. COSA TI FI8IdIGroup
18. AYliI8bll1y SIat8m8nt 18. S8a811y CIaa (ThI8 A8part) 21. No. of Page8
None 66
20. S8a811y CI8u (1hI8 1'80-) 22. Prtce
Nonp
ANSI-Z38.18 .",. on ".
1-
50272-101
(See
S-/naINCfI
-
(formaoty NTIS-35)
Dapannanl of Comnwce
-------
EPA/ROD/R04-91/091
Ciba-Geigy, AL
Second Remedial Action
Abstract (Continued)
treatment of the contaminated shallow alluvial aquifer by using the onsite wastewater
treatme~t plant as Operable Unit 1 (OU1). This ROD addresses highly contaminated soil
and sludge at 10 of the 11 former waste management areas as OU2. Future RODs will
address contamination within the floodplain including the lower portions of an onsite
drainage ditch and areas in the Tombigbee River in proximity of the site (OU3), and
contamination in the remaining untreated former waste management area and the upland
portions of the drainage ditch (OU4). The primary contaminants of concern affecting
the soil, sludge, and debris are VOCs including benzene and toluene; other organics
including PCBs and pesticides (e.g., DDT); and metals including lead.
The selected remedial action for the site includes excavating contaminated soil and
sludge from within the 10 disposal areas until established clean-up levels are reached
or to a maximum depth of 20 feet; treating 65,000 cubic yards of highly-contaminated
soil and sludge onsite using thermal treatment; evaluating the possibility of
pretreatment via solvent extraction, low temperature thermal treatment, or critical
fluid injection and implementing this process, if advantageous; treating 62,300 cubic
yards of moderately contaminated soil and sludge using stabilization/solidification or
a proven innovative technology; obtaining a treatability variance to dispose of the
treated soil and residual ash in an onsite landvault; treating deep soil areas, where
risk-based levels have not been achieved during excavation to the depth of 20 feet,
using in-situ soil flushing combined with isolation walls, extraction wells alone, or
possibly extraction wells in combination with in-situ vacuum extraction or in-situ
bioremediation, whichever is found to most effective; backfilling and revegetating the
excavated areas; operating and maintaining the landvaults for a minimum of 30 years;
monitoring ground water; and implementing institutional controls where necessary
including land and ground water use restrictions. The present worth costs for this
remedial action range from $94,000,000, if solidification of low level contaminated
soils is effective, to $120,250,000, if incineration of all contaminated material is
required. O&M costs were not provided.
PERFORMANCE STANDARDS OR GOALS: Chemical-specific soil clean-up goals are based on
soil depth. For soil to a depth of less than 12 inches, goals are based on 10-6 risk
level for carcinogens, and an HI=l for non-carcinogens. Chemical-specific goals for
surface soil include DDT 17 mg/kg. Subsurface soil clean-up goals are based on
ground water protection levels, as well as a 10-4 risk level for carcinogens and an
HI=l for non-carcinogens, and include DDT, 5,034 to 7,500 mg/kg depending on the area.
-------
DECLARATION
of the
RECORD OF DECISION
OPERABLE UNIT TWO
SITE NAME AND LOCATION
Ciba-Geigy Site
. McIntosh, Washington County, Alabama
STATEMENT OF BASIS AND PURPOSE
This decision document (Record of Decision), represents the selected
remedial action for Operable Unit Two for the Ciba-Geigy Site,
McIntosh, Alabama, developed in accordance with the Comprehensive
Environmental Response, Compensation and Liability Act of 1980
(CERCLA), as amended by the Superfund Amendments and Reauthorization
Act of 1986 (SARA) 42 U.S.C. Section 9601 et seq., and to the extent
practicable, the National Contingency Plan (NCP) 40 CFR Part 300.
This decision is based on the administrative record for the
Ciba-Geigy Site.
The State of Alabama has concurred on the selected remedy.
ASSESSMENT OF THE SITE
Actual or threatened releases of hazardous substances from the
Ciba-Geigy Site, if not addressed by implementing the response
selected in this ROD, may present an imminent and substantial
endangerment to public health, welfare or the environment.
action
DESCRIPTION OF SELECTED REMEDY
This operable unit is the second of four proposed operable units.
The first operable unit at this Site addressed contamination of the
shallow (alluvial) aquifer. Operable unit two, which is the subject
of this Record of Decision, addresses a principal threat, the hiqhly
contaminated soils and sludges at ten of the eleven former waste.
management areas. Operable unit three will address contamination
within the floodplain including the lower portions of dilute ditch
and areas in the Tombigbee River within close proximity to the Site.
Operable unit four will address contamination in former waste
management area 8 and the upland portions of the dilute ditch.
The major components of the selected remedy for operable unit two
include:
Excavation of contaminated soils and sludges until established
cleanup levels are reached or until excavation becomes
technically impracticable (i.e., depths in excess of 20 feet),
whichever is reached first:
-------
On-site thermal treatment of approxLmately 65,000 cubic yards of
highly contaminated soils and sludge;
Stabilization/solidification or the utilization of an innovative
technology proven effective during the remedial design, of
approx~tely 62,300 cubic yards of moderately contaminated soils
and sludge:
Disposal of treated soil and residual ash from the thermal
treatment process in an on-site RCRA MinLmum Technology Subtitle
C landvault(s):
In-situ soil flushing combined with isolation walls and
extraction wells to remediate areas where the risk based cleanup
levels are not achieved before an excavation depth of 20 feet is
reached. Innovative technologies (in-situ vacuum extraction or
in-situ bioremediation) may also be used in addition to or
instead of in-situ soil flushing, if during the remedial design
either technology is found to be effective in reducing
contaminant concentrations in the soil and is cost effective. If
either technology is proven to be more effective than in-situ
soil flushing in reducing the concentrations of the contaminants
in the soil and more cost effective, it will be used instead of
in-situ soil flushing. If either technology is not as effective
as in-situ soil flushing in reducing the concentration of the
contaminants in the soil it will not be utilized in place of
in-situ soil flushing, however, it may be used in concert with
in-situ soil flushing if the combination enhances the remediation
and is cost effective.
Issuing a public notice in a local newspaper and sending a fact
sheet to persons on the mailing list at the completion of the 30%
design report. The purpose of the fact sheet and the public
notice would be to inform the public of the technologies selected
that were proven effective during the treatability studies
conducted during the remedial design:
Backfilling the excavated areas with common fill and vegetating
the area and the establishment of a suitable vegetative cover:
Operation and maintenance of landvault(s) for a minLmum of thirty
years: and
Institutional controls for land use and groundwater use
restrictions.
STATUTORY DETERMINATIONS
The selected remedy is protective of human health and the
environment, complies with federal and state requirements that are
legally applicable or relevant and appropriate, and is
cost-effective. This remedy satisfies the preference for treatment
that reduces toxicity, mobility, or volume as a principal element.
Finally, it is determined that this remedy utilizes a permanent
solution and alternative treatment technology to the maximum extent
practicable.
-------
Because this remedy will result in hazardous -substances remaining
on-site at the areas addressed by operable unit two above
health-based levels, a review will be conducted within five years
after commencement of the remedial action to ensure that the remedy
continues to provide adequate protection of human health and the
environment.
~h1/~"'" ~
r GREER C. TIDWELL, REG 0 INISTRATOR
SEP 38 1991
DATE
-------
RECORD OF DECISION
SUMMARy OF REMEDIAL ALTERNATIVE SELECTION
CIBA-GEIGY SITE
OPERABLE UNIT TWO
Me INTOSH, WASHINCGTON COUNTY, ALABAMA
PREPARED BY:
U. S. ENV1RONMENTAL PROTECTION AGENCY
REGION IV
ATLANTA, GEORGIA
-------
6.2 Alternative No. 2 -
6.3 Alternative No. 3 -
6.4 Alternative No. 4 -
6.5 Alternative No. 5 -
1.0
1.1
2.0
3.0
4.0
5.0
6.0
6.1
1.0
1.1
1.2
1.3
1.4
1.5
1.6
1.1
TABLE OF CONTENTS
Site Location and Description.............
Site History and Enforcement Activities...
......
. . . .1
....1
.......
........
Highlights of Community Relations.....
........6
...............
Scope of Operable Unit..........
......................
.......7
Snmmary of Site Characteristics..............................8
4.1 Geology-/Soils. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
4 . 2 Hydrogeology-. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4.3 Surface Water......................................... .10,
4.4
Sample Results From Former Waste Management Areas......11
Summary- of Site Risk....................................... .16
5.1 Contaminants of Concern............................... .16
5.2 Exposure Assessment... .............................19
5. 3 Toxicity Assessment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
5.4 Risk Characterization............ .................24
5.5 Environmental Risk....
5.6 Cleanup Goals..........
... ... ..... .......... ....
...30
...30
... .......... ......... ...
Description Alternatives....
..... ............ ........ ....
...33
Alternative No.
1 - No Action....
......... ... ..... .......
. . .33
Containm.ent. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Removal, Stabilization/Solidification,
and On-Site Disposal....................34
Removal, On-Site Thermal Treatment, and
On-Site Disposal........................35
Removal, On-Site Thermal Treatment, and
On-Site Disposal........................36
Criteria Used Por The Analysis of Alternatives..............38
Overall Protection of Human Health and the Environment......39
Compliance With ARA,R,S.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40
Long-Te~ Effectiveness and Permanence......................40
Reduction of Toxicity, Mobility or Volume Through Treatment.4l
Short-Term Effectiveness..
.. ........ ....... ........ ......
...41
Implementability..........
........... ....................
...42
Cost. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
-i-
-------
7.8
7.9
8.0
9.0
9.1
9.2
9.3
9.4
9.5
10.0
TABLE OF CONTENTS
- cont. -
State Acceptance..................,.......................... 43
Communi ty Acceptance.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
SUDIII1ary of Selected Remedy.................................. 43
Statutory Determination..................................... 49
Protective of Human Health and the Environment..............50
Attainment
of .ARAR.s......................................... 50
Cost Effectiveness.......................................... 52
Utilization of Permanent Solutions to the Maximum
Extent Practicable..................................... 52
Preference for Treatment as a Principal Element.............53
Significant Changes......................................... 53
Appendix A - Responsiveness Summary
Appendix B - Concurrence Letters
-ii-
-------
Table 4-1
Table 4-2
Table 5-1
Table 5-2
Table 5-3
Table 5-4
Table 5-5
Table 5-8
Table 5-9
Table 8-1
LIST OF TABLES
Soils Area-Wide - Analytes Detected......................12
Soil "Area-Wide For The Selected Contaminants Of Concern..13
Soils RI Study Area - Analytes Detected..................17
Health Effects Criteria For Oral Ingestion
Of Chemicals Of Concern..................................22
Health Effects Criteria For Inhalation Exposure to
Chemicals Of Concern..................................... 23
Comparison of Soil Concentrations of Selected
Contaminants with Health-Based Soil Concentrations.......26
Summary of Risk for Future Worker Exposure to Surficial
Soils in Area 2, Eastern Portion of Area 3 and Area 9....29
Groundwater Cleanup
Levels. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
Soil Cleanup Levels For Groundwater Protection...........32
Treatment Standards For Soils At The Ciba-Geigy Site.....47
-iii-
-------
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
LIST OF FIGURES
Clba-Geigy Corporation, Vicinity Map......................2
51 te Locations............................................ 4
Generalized Geologic Cross-Section........................9
Process Flow Chart for Treatment of Contaminated
Soils. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44
Deep Soil Remediation Flow Chart.........................48
-iv-
-------
Dec is ion Smmn;l ry
Record of Decision
Operable Unit Two
Clba-Geigy Site
McIntosh, Alabama
1.0 SITE LOCATION AND DESCRIPTION
The Ciba-Geigy Corporation McIntosh facility is located in southern
Washington County, northeast of McIntosh, Alabama, approximately 50
miles north of Mobile, Alabama (Figure 1). The operating facility is
located at 310 l5'00R north latitude and 870 58'00" west
longitude. The operating facility, which encompasses approximately
2.4 square miles, is situated between the Southern Railroad
right-of-way on the west and extends nearly to the escarpment
separating the upland terrace from the floodplain of the Tombigbee
River. The property boundaries extend beyond the railroad westward
toward U.S. Highway 43. The northern edge of the property merges"
into an undeveloped pine forest. To the south the property is
bounded by Olin Corporation facility. The southeastern portion of'
the property extends to the banks of the Tombigbee River.
The facility is located in an industrial setting. The Ciba-Geigy
Superfund Site (RSiteR) is contiguous with the facility boundary.
The Areas of Contamination (AOCs) addressed by this ROD are located
on the McIntosh facility due east of the current production area.
The AOCs are roughly divided by the river water reservoir (see Figure
2). The nearest population center is the town of McIntosh, which is
located approximately two miles to the southwest.
1.1
SITE HISTORY AND ENFORCEMENT ACTIVITIES
The Ciba-Geigy McIntosh facility, formerly owned by Geigy Chemical
Corporation, began operations in October 1952, with the manufacture
of one product, dichlorodiphenyl-trichloroethane (DDT). Through
1970, Geigy expanded its McIntosh facilities by adding the production
of fluorescent brighteners used in laundry products; herbicides;
insecticides; agricultural chelating agents; and sequestering agents
for industry.
In 1970, Geigy merged with Ciba (Chemical Industry in Basel,
Switzerland), forming the Ciba-Geigy Corporation. Since then
Ciba-Geigy has continued to expand its operations with the added
production of resins and additives used in the plastics industry,
anti-oxidants, and small-volume specialty chemical products (i.e.
water treatment chemicals and fire fighting foams). The present
facility occupies approximately 1,500 acres and employs about 1,200
workers.
The EPA Region IV Environmental Services Division of Athens, Georgia
(ESD) conducted an investigation in August 1982 of the Olin Chemical
Company located adjacent to the Ciba-Geigy Site. As a part of the
investigation, ESD sampled a drinking water well on Ciba-Geigy
property. This sampling indicated the presence of hazardous
-------
:--.....
~=~..
~
-1-
'.
\
".
\
I(
\
1
,
1
t
I
t
.;3
REI'I£OI'\L
OC~ PAO~£C1 NO C~-.2:C-:1
CIB,\-GEIGY :ORPCR.TICS
INvESTIG~TION / FE~SIS]~ITY S;~:Y
FIGURE 1
VICINITY MAP
MCIHT~C'" .0." .....-
t
r
,-:\.-.., I\('M ,..RIl
POOR QUALITY
ORIGINAL
-------
-3-
substances which warranted further evaluation of the contamination
problem at Clba-Geigy. In June 1983, the Hazardous Ranking System
(HRS) survey was completed and the Site was assigned a ranking of
53.42. The Clba-Geigy McIntosh Plant was included on the National
Priorities List (NFL) in September 1983.
In October 1985, EPA issued Ciba-Geigy a RCRA permit, which included
a corrective action plan requiring Ciba-Geigy to remove and treat
contaminated groundwater and surface water at the site. The
corrective action plan stipulated that Ciba-Geigy would prepare a
Remedial Investigation/Feasibility Study (RIfFS) for the disposal
areas being studied by the Superfund program. Figure 2 depicts the
location of CERCLA areas within the Ciba-Geigy Site.
The ten units closed under the RCRA permit include:
Diazinon Wastewater Sewer: Utilized to pipe Diazinon waste
to the Diazinon Destruct Impoundment. Closure under post
closure care in 1976.
Triangular Impoundment: Constructed in the 1970s to
decompose Diazinon residues. Closure during interim status
completed in 1986.
Rectangular Impoundment: Constructed in 1972-1973 to hold
sludge from the dilute impoundment. Closure during interim
status completed in 1987.
Class C Landfill: Permitted by Alabama in 1973 and permitted
under RCRA Interim Status regulations. Closure during
interim status completed in 1987.
Biological Sludge Landfill: Permitted by Alabama in 1978 and
later operated under RCRA Interim Status for disposal of
dewatered sludge. Closure during interim status completed
in 1987.
Diazinon Destruct Impoundment: Constructed in 1965.
Closure under post closure care completed in 1989.
GK-44 Impoundment: Put into service in early 1970s.
Coft8tructed for the GM-44 wastes high in nitrogen compounds.
Its use was discontinued in the late 1970s. Closure under
post closure care completed in 1989.
Effluent Diffuser Line: Constructed in late 1968 to convey
effluent for discharge into the Tombigbee River. Taken out
of service in 1973 due to a change in the wastewater
treatment system, closure of RCRA impoundments, and a change
in the NFDES permit.
Effluent Disposal Well: Installed in 1971. Used for the
injection of biotreated effluent to reduce the quantity of
HaCl discharged into the river. The use of the well was
unsuccessful and it was plugged in 1983. ADEM required no
post-closure monitoring.
-------
FIGURE Z
j - - - - - - - -
, CI8A-GEIGY ~". 'Bo~nd;"; . . . . . . . . . . - - - - - - . . - . - - - . . . -,
, ,
, '
, ,
, DISPOSAL,
SITE
, SOUTH Off '
, THE CLASS '
, C~~'
, TRASH 7 .
. , STAGING ~ .
, AREA'
: 11----~ .
, ~~.
, AREA ~ / .
: . ~--r-~V. ....
, ;f~TEMPORAAY..
, . TRASH. .
, " .. STAGING.
, I.. AREAS ..
.. .
. .
-. .
. .
. .
. . .
. .
.
.
I
AREA OF CONTAMINATION I
@
-.....--..---..........1
CIBA - GEIGY CORPORATION
PLANT SITE
MciNTOSH. ALABAMA
..
-------
-5-
Dilute Ditch: This ditch collected dilute wastewater and
surface water runoff to be conveyed to the Dilute
Impoundment. Use ceased in 1971.
Pursuant to the Corrective Action portion of the permit, in 1987,
Ciba-Geigy installed a groundwater pumping system to intercept and
. remove contaminated groundwater from the shallow alluvial aquifer.
The water removed from these wells was treated in the plant's
existing on-site wastewater treatment system until fall 1988, when
the plant's new biological wastewater treatment system was completed
and used to treat the groundwater. The treated water is discharged
into the Tombigbee River in compliance with appropriate National
Pollutant Discharge Elimination System (NPDES) Regulations.
Ciba-Geigy has installed four (4) corrective action monitoring wells
along the southern boundary of the property to monitor the
effectiveness of the pumping well system. The effectiveness of the
pump and treat system in preventing the migration of contaminated
groundwater off-site and reducing the concentrations of contaminants
in the groundwater is well established.
EPA completed the Superfund decision document (the Record of Decision
or ROD) for operable unit one in September 1989 after public comments
were carefully considered. The ROD identified the EPA selected
remedy, "No Further Action". This selection was based on and
concurred with the groundwater pump and treat system installed under
the RCRA permit to address groundwater contamination in the shallow
aquifer at the Site.
In accordance with the corrective action plan, Ciba-Geigy retained
BCM, a technical consultant, to perform the RI/FS. Field work, which
began in October 1985, was conducted by BCM on Ciba's behalf, with
EPA's oversight. The principal finding of the RI study was the
definition of the extent of contamination from eleven additional
waste management areas within the study area that will be addressed
under CERCLA.
The CERCLA Site has been grouped and divided into two Areas of
Contamination (ACe) based on their relative proximity to each other.
The AOCs are roughly separated by the reservoir (See Figure 2).
EPA will continue its CERCLA enforcement activities and will send a
Special Notice Letter to Ciba-Geigy prior to the initiation of the
remedial d..ign for the selected remedial action. Should Ciba-Geigy
decline to conduct future remedial activities, EPA will either take
additional CERCLA enforcement actions or provide funding for these
activities while seeking cost recovery for all EPA-funded response
actions at this Site.
-------
-6-
2.0
HIGHLIGHTS OF COMMUNITY RELATIONS
The RI for the Ciba-Geigy Site was released to the public in
August 1988. The FS and the Proposed Plan for the Ciba-Geigy
Site were released to the public on July 30, 1990. These
documents were made available by placement in both the
administrative record docket and the information repository
maintained at the EPA docket room at Region IV Headquarters in
Atlanta, Georgia and at the McIntosh Town Hall, in McIntosh,
Alabama. Pursuant to regulations, a public comment period was
held from July 30, 1990 through August 30, 1990. A notice was
published in the Mobile Press Register on July 31, 1990
announcing the comment period. In addition to the public
comment period and the administrative record files, a public
meeting was held on August 16, 1990 in McIntosh Alabama. At
this meeting, representatives from EPA, and ADEM answered
questions and addressed community concerns.
After review of comments received during the comment period, EPA
issued an Amended Proposed Plan to clarify the alternatives
considered for the cleanup of contamination found at the
Ciba-Geigy Site. A notice was published in the Mobile Press
Register on February 7, 1991 announcing the comment period. The
comment period for the Amended Proposed Plan began February 4,
1991 and ended MArch 6, 1991, with a public meeting scheduled
for February 20, 1991 if a written request was received by EPA
no later than February 13, 1991. A request to extend the
comment period was received and granted, however no requests
were received to conduct a public meeting. The extended public
comment period ended April 5, 1991.
Based on the written comments received during the comment period
for the Amended Proposed Plan, EPA issued the Modification to
the Amended Proposed Plan in July 1991. A notice was published
in the Mobile Press Register on July 15, 1991 announcing the
public comment period which ended August 18, 1991. EPA provided
the opportunity for an additional public meeting on August 6,
1991 upon written request to the Agency. No request for a
public meeting was received.
A response to all significant comments received during the
public c0m88nt periods is included in the Responsiveness Summary
which is a part of this Record of Decision.
This decision document presents the selected remedial action for
operable unit two of the Ciba-Geigy Site, chosen in accordance
with CERCLA, as amended by SARA and to the extent practicable,
the NCP. The decision for this Site is based on the
administrative record. The requirements under Section 117 of
CERCLA/SARA for public and state participation have been met for
this operable unit.
-------
I --
I
I
3.0
-7-
SCOPE AND ROLE OF OPERABLE UNIT
Due to the size of the facility, the number of areas and the
variety of contaminants, the problems at the Ciba-Geigy Site are
complex. As a result EPA initially organized the work into three (3)
operable units (OUs). The operable units at this Site as identified
.in the initial ROD issued for operable unit one in September 1989
are:
OU 11
OU 12
Contamination of the shallow (Alluvial) groundwater aquifer.
Contamination of the deep (Miocene) groundwater aquifer, if
contamination was found during additional sampling.
Contamination of soils at eleven (11) former waste
management areas to be addressed under CERCLA authority..
In June 1989, additional sampling of the deep (Miocene) groundwater
aquifer was conducted by Ciba-Geigy and a Groundwater Review' Update
Report was presented to ADEM and EPA. The results from the sampling
showed no contamination present in the deep aquifer. If further
sampling data ShOWB the presence of contamination, the Miocene
aquifer will be re-evaluated. However, as a result of the present
findings, Operable Unit '2, as identified above, will now address
contaminated soils in ten of eleven former waste management areas.
Two additional Operable Units are currently planned to address other
contamination at the Site.
OU 13
The Operable Units have been redefined as follows:
OU 11
OU 12
OU 13
OU 14
Contamination of the shallow (Alluvial) groundwater aquifer.
Contamination of soils at ten of eleven former waste
management areas.
Contamination within the floodplain, the lower portion of
the dilute ditch and areas in the Tombigbee River within
close proximity to the Site.
Contamination of soils in former waste management
Area 8 and the upland portion of the dilute ditch.
Operable Unit .2 addresses the contamination of soils at selected
former waste management areas. The January 1990 Draft Feasibility
Study submitted by Clba-Geigy documents the development, screening
and detailed evaluation of potential alternatives for remediation of
eleven former waste management areas identified and characterized
during the Remedial Investigation. EPA has evaluated the
alternatives and the risk posed by the contaminants as they relate to
the "CERCLA" site. Based on this evaluation, EPA has determined the
alternative or combination of alternatives which will achieve the
CERCLA cleanup objective, to remediate the source of contamination
-------
-8-
and prevent current or future exposure to contaminated
groundwater at ten of eleven former waste management areas.
This operable unit is consistent with past work conducted at the
Site and future work to be conducted.
4.0
4.i
SUMMARY OF SITE CHARACTERISTICS
GEOLOGY/SOILS
The Ciba-Geigy property is located within the Southern Pine
Hills, which are elevated features that regionally slope
southward toward the Gulf of Mexico. These hills are dissected
by various river systems that feed into the Gulf. The plant is
located upon a low terrace adjacent to the Floodplain of the
Tombigbee River. The property lies within the boundaries of the
Mobile Graben, a downthrown fault block paralleling the river.
The surficial and shallow geology can be broken into three
distinct features. The uppermost layer is a relatively
continuous clay layer containing sand and silty sand lenses and
clay layers that range from only a few feet to over 50 feet in
thickness. Underlying the clay layer are Pleistocene-age
alluvium and low terrace deposits of interbedded gravel, silt,
and clay with thicknesses ranging from 60 to 100 feet. These
deposits outcrop throughout the area.
Underlying the low terrace deposits are alternating layers of
Miocene-age gravels, sands, and clays. Regionally, Upper
Miocene clay hydraulically separates the Miocene and Pleistocene
deposits (See Figure 3).
Erosion and redeposition of these sediments reflect dynamic
depositional environments which are common on a regional scale.
This has resulted in a complex subsurface stratigraphy.
Variations of physical characteristics (e.g. porosity, grain
size, hydraulic conductivity) both vertically and laterally
within the strata complicate the movement of water in the
subsurface. Nine different soil series are located within the
area of the plant. These soils are generally loamy clays and
sands that range from well drained to poorly drained.
permeability of the soil ranges from moderate to low.
4.2
HYDROGEOLOGY
Both the Pleistocene and Miocene strata are water
represent two distinct aquifers, the Alluvial and
Miocene. They are separated by a number of shale
aquitards and aquicludes.
bearing and
Upper
and clay
-------
Ci)
m
z
m
:u
>
r-
I: 0 N
n - m
- OJ 0
~ > "
o I II'
(8 Ci) m:D
~m om
- r- I:
~ Ci) 0 =
~ ~ Ci)
8- -
.z 0
fp 0
:u
o
en
en
en
m
o
....
(5
Z
(,.)
80 - LAND SURF ACE
.. :::::::::::::::.::"': '::~::::':::",,: 5
w
z
w
o
o
~
~
~
z
o
t=
~
III -120-
""'0 - :
-80-
-180 -
-200-
~
-
a
c
:u
"'
z
o
-
- -
- -
-1I~r
~ -
..
"
:
..
"
LEGEND
o
o
CLAY
SAND
- -
~
-
"rj
,....
IQ
I-
'1
m
'-'"
. .
----
NOTES:
1. ELEVATIONS RELATIVE TO
MEAN SEA lEVEL
2. BASED ON SOil BORING
DA T A FROM PElA 198" 8
-------
1-
-10-
The Alluvial aquifer is composed of the recent and Pleistocene
terrace and alluvial deposits. The thickness of the aquifer and
the water level depend on the thickness and configuration of the
overlying clay layer. Under natural, semi-confined conditions,
the saturated thickness of the Alluvial aquifer ranges from less
than 30 feet to over 50 feet. Recharge of the ~luvial aquifer
comes locally, from rainfall, streams, and reservoirs. High
floods in the river floodplain also recharge the aquifer.
The groundwater flow of the Alluvial aquifer normally slopes
gently to the south-southeast toward the Tombigbee River.
However, the flow of groundwater is modified by the pumping and
capture of contaminated groundwater by the plant and recharge
from the site reservoir. This system was designed to reduce the
level of contaminants in the groundwater below the facility and
prevent further migration of the contaminated groundwater. The
concentrations of contaminants present in the groundwater has
decreased and the operation of the intercept wells has reversed
the direction of groundwater flow as a result of the pumping.
The Upper Miocene underlying the plant is a confined aquifer of
sands and gravels capped by a clay layer about 100 to 130 feet
in thickness. Recharge of this aquifer is believed to come from
regional infiltration in outcrop areas that up-dip to the
north. In contrast to the Alluvial aquifer, the quality of
Upper Miocene water can be effected by regional influences such
as salt domes or saltwater intrusion from the Gulf of Mexico.
Paleo-channeling has been found to exist in the surface of the
Miocene clay. However, during the investigation for the
Groundwater Corrective Action Program, and as a part of the
RIfFS, it was determined that the two aquifers are not
hydraulically connected.
4.3
SURFACE WATER
-
The Ciba-Geigy facility property lies within the Tombigbee River
Basin which has a drainage area of 8,378 square miles. The
Tombigbee River flows past the Site, converging further south
with the Alabama River to form the Mobile River.
Surface water features at the Ciba-Geigy plant include the
diverted Johnson Creek on the northern edge of the property, and
a large, man-made reservoir between the manufacturing area and
the waste management facilities. Surface water runoff on the
northern, undeveloped corner of the property drains off-site
through ditches into the Tombigbee River. The surface water
-------
-11-
system south of Johnson Creek has undergone extensive change.
In addition to a new wastewater treatment system, a new
stormwater management system has been constructed to replace the
old combined dilute wastewaterlstormwater system, which used
stormwater sewers, open surface ditches, and the dilute ditch to
convey mixed dilute wastewater and stormwater to the dilute
impoundment. The new system segregates all wastewater, dilute
and process, to the wastewater collection and transfer system
and then on to the biological wastewater treatment system. All
stormwater sewers have been renovated and all open ditches have
been replaced with stormwater sewers draining to stormwater
retention tanks capable of holding a one-inch rainfall over the
entire developed manufacturing area of the plant. All initial
rainwater retained is transferred to the biological wastewater
treatment plant. All stormwater overflow (rainfall above one
inch) is diverted to established drainageways discharging to the
Tombigbee River.
4.4
SAMPLE RESULTS FROM FORMER WASTE MANAGEMENT AREAS
The primary emphasis for analytical testing during the RI was to
determine the nature and extent of the soil contamination at the
Site. As a result, soil and waste samples were collected and
analyzed to determine the chemical contamination present at the
Site. The following is a brief description and a volume
estimate of each of the ten (10) waste management areas to be
addressed in operable unit two, under CERCLA authority.
Table 4-1 summarizes the maximum, minimum and median
concentration and detection frequency for the contaminants found
in the soil throughout the Site. During the developement of
this ROD it was determined, based on toxicity, mobility, and
frequency of detection, that if certain contaminants were
excavated and remediated to acceptable levels, the remaining
contaminants would also be excavated and remediated to
acceptable levels. The selected contaminants of concern are
presented in Table 4-2 (also see section 5.1).
AREA 1
(OriainAl Bffluent TBWWn1ndment)
Area 1 is a former wastewater impoundment currently filled in
with material from sandblasting activities. The waste at AREA 1
is sludge containing pesticide residues, by-products, and
intermediates from pesticide manufacturing. Some of the waste
in Area 1 extends into unconsolidated soils within a saturated
zone. The estimated volume of contamination in Area 1 is 12,500
cubic yards.
-------
Table ':'-1
CHEMICALS OF POT:MTIAL C~NCERN iN STUOY.~IOE SOILS
CIBA-GEIGY MciNTOSH FACILITY
Concentrations (mg/kg)
........-...-........... ....-.... Detection
AnalyteS Mininun Maximun Frequency (I)
volatile Organics
.........",.",.-.........-
Acetone 0.01'5 601, 79 - 9l.
Benzene BMOL 5650 32 - 9/.
Carbon disulfide BMOL 162 6 - 9l.
Chlorobenzene BMDL 1014 109 - 910
ChlorofOMl 0.0067 16600 18 - 9'
Ethyl benzene BMOL 72300 26 - 9'
m-Xylene BMOL 1810000 29 - 910
Methylene chloride BMOL 373 66 - 910
o+t)- Xy I enes BMDL 67100 27 - 910
Tetrachloroethylene 0.0053 2070 5 - 910
Toluene BMOL 6360 38-910
Base/Neutrel Extrectables
---..--....-..-........---
1,2,'-Trichlorobenzene BMOL 81 22 - 89
1,2-0ichlorobenZene BMDL 107 23 - 89
1,lo-Oichloroben1ene BMDL 546 31 . 89
Aniline BMDL 1100 7 - 89
Nitrobenzene BMOL 746 20 . 89
Acid Extractables
-.-......----...-
2,Io,6-Trichlorophenol 0.729 120 5 - 92
2,'-Oichlorophenol 0.111 11.5 6 - 92
Chlorinated Pesticidet
....-.-.-...............
",'" -ODD IJIItDL 8560 50 - 89
4,4'-00E 0.255 81010 100 - 89
4,'" 'OOT BNOL 3780 41 - 89
Alplle-BHC BMDL 4370 34-89
Beta-SHC BMDL 7'51 19 . 89
GI/IIU-BHC BMDL 7'53 11. . 89
Manufactured Pesticides
---.------...-.-.--.----.
Alllet ryn BMDL 310 19 - 94
Atruine BMDL 4310 2' - 94
Chiorobenziiate BMOL 650 31. - 94
Chloropropylate 0.2 522 22 - 94
Cyanez ine BMOL 960 20 - 910
Oiazinen IJIItDL 786 36 - 910
Galecron IJIItDL 7'50 " . 94
Methidathion (Supracide) SMOL l.7 13" - 910
Metolechlor (Duel) IJIItDL 150 17 - 910
Pr~ton SMOL 64 35 - 94
Prometryn IJIItDL l.10 28 - 94
Propezine BMOL 117000 11 - 94
Simazine 0.110 1100 32 . 910
Terta8lton BMOL 8700 22 . 910
T erbutryn 0.1 SS7 19 . 910
T erbutlayL u i ne BMOL 327 2l. - 9'
Tol'" BMOL IS200 36 - 910
Metal.
Arsenic BMOL 1S0 810 . 91
ChrOlliu. 1.3 1490 91 - 91
C~r 0.99 22S0 (b) 91 - 91
Leed BMOL 180 91 . 91
Cyanides
----.e..
Cyanide, Total BMOL 10.5 9l. . 910
BMDL . Belo.. _thod detection limit
(a) Rtpr..8f\U the IUICIr of s8lllPies in wnich the chemical..., detected
per the total number of analyZed saMples.
(b) The ...i8U8 copper concantrttion in study-wide soils shown in tne RI Report
(101 1988) and prnented on pege A-3 in AppenClia A is 131,000 1liii/kg- This
",alue "'~8d on the analysis of I18ste in a drUI in Zona 8. This l18ate
_teri.l hea bHn ~8d and i. no longer repre.ant8tive 0' .ite
condlttGn8. The value ShOMn I. the highnt -.sured soil concentration
excluding this weste I8IIIPle.
-------
TABLE 4-2
SOILS AREA-WIDE - ANALYTES DETECTED
POR THE SELECTED CONTAMINANTS OF CONCERN
CONCENTRATIONS (mg/kg) Detection
. Analytes Hinimum Median Maximum Frequency
Volatile Organics
Benzene BMDL 0.331 5650 32 - 94
Chlorobenzene BMDL 0.129 414 49 - 94
Chloroform 0.0067 0.372 16600 18 - 94
Toluene BMDL 0.267 6360 38 - 94
Pesticides/PCBs
4,4'-DDD BMDL 15.8 8590 50 - 89
25.6
4,4'-DDE 0.255 15.7 8410 40 - 89
17.8
4,4'-DDT BMDL 29.6 3780 41 - 89
Alpha-BHC BMDL BMDL 4370 34 - 89
Beta-BHC BMDL 5.13 751 19 - 89
Delta-BHC BMDL 2.16 315 15 - 89
Ganuna-BHC BMDL BMDL 753 14 - 89
BMDL
Manufactured Pesticides
Chlorobenzilate BMDL BMDL 650 34 - 94
Diazinon BMDL 2.3 786 36 - 94
Metals
Lead BMDL 14 180 91 - 91
*
BMDL When a compound or element is present below its published
MDL (it is reported as BMDL (below method detection limit)
MDL The priority pollutant compounds and elements are listed
with their NPDES numbers and the method detection limit
(MDL) published in the Federal Register
*
Detection prequency - The number of times a contaminant was found
with respect to the number of times it was analyzed for (i.e.,
32-94 means the contaminant was found in 32 of 94 samples)
-------
-14-
AREA 2
(Waste OisDOsal Pit}
Area 2 is a small, former disposal pit covered by fill located
~ediately east of Area 1. The pit contains waste consisting
of trash, pesticide residues, by-products, and intermediates
from pesticide manufacturing. The est~ated volume of
contamination in Area 2 is 2,100 cubic yards.
AREA 3
(Tar Oisoosal Area)
Area 3 is an area consisting of five discrete past waste
management areas evidencing broad surficial contamination.
Based on the field work conducted during the RIfFS, Area 3 has
been divided into 5 specific areas and a general area of
contamination based on differences in colors of the waste. The
area now includes areas 3A, 3B, 3C, 3D, 3E and 3 General.
Area 3A's waste consists of a white and pink chemical solid.
Some of the material is located with deteriorated steel drums.
Area 3B's waste is a viscous clear to amber liquid and a
greyish-blue solid. Drums were encountered at four feet. Area
3C's waste consists of white solids. Deteriorated drums were
encountered two feet below the surface. Area 30's waste
consists of seven feet of clayey silt fill containing burnt
wood, shell and organic debris. A five foot layer of black
tar-like solid waste was encountered beneath the fill. Area
3E's waste consists of an approximately ten foot thick layer of
clayey silt fill material containing shell, concrete, burnt
wood, charcoal and chemical waste which overlies undisturbed
soil. Area 3 general includes an area with a thin tar layer and
contaminated soil, the stockpile area, and a former cooling
water ditch with associated contaminated soil. The stockpile
area contains intermixed soil and waste excavated during
construction of the new cooling water discharge pipeline.
Contaminated sediments in the eastern segment of the former
cooling water ditch were also transferred to the stockpile area
during construction of the new cooling water discharge pipeline.
The estimated volume of contamination in Area 3 is 51,100 cubic
yards.
AREA 4
,v.-te Disoosal Pits)
Area 4 consists of three isolated, shallow disposal pits; Areas
4A, 4B, and 4C, which are covered by clay fill. The pits
contain pesticide residues and intermediates from pesticide
manufacturing. Area 4A's waste consists of two feet of dark
grey solid below six feet of fill. Area 4B and 4C's wastes were
determined to be identical and consist of two feet of black
solid waste with green and yellow streaking covered by six feet
of fill. The estimated volume of contamination in Area 4 is
2,500 cubic yards.
-------
-15-
AREA 5
(ODen Burn Area}
Area 5 is an area where open burning was formerly practiced.
The area is covered by clay fill and contains trash, burned
demolition debris, pesticide residues, by-products, and
intermediates from pesticide manufacturing. The estimated
volume of contamination in Area 5 is 8,200 cubic yards.
AREA 6
(~rarv Trash Staaina Area)
Area 6 is the location of two adjacent former trash staging
areas covered by clay fill. The site contains trash consisting
of combustible refuse such as plastic, paper, cardboard, and
rubber intermixed with manufactured pesticides and metals. The
estimated volume of contamination in Area 6 is 10,400 cubic
yards.
AREA 7
(DisDOsal Site South of the Class C Landfill}
Area 7 is a former disposal pit covered with clay fill. The
area contains drums, solid waste, jars, bulk solid wastes, and
trash. The waste is comprised of pesticide residues,
by-products, and intermediates from pesticide manufacturing.
The estimated volume of contamination in Area 7 is 7,400 cubic
yards.
AREA 8
(Bluffline Area}
Area 8 will be addressed in Operable Unit #4.
AREA 9
(BBC Burial Area)
Area 9 is a chemical material burial area covered with clay
fill. The area contains bulk pesticide by-products,
predominantly isomers of SHC, and residues. The estimated
volume of contamination in Area 9 is 32,100 cubic yards.
AREA 10
,warehouse Ro. 218)
Area 10-conalsts of a thin layer of waste partially covered by
an existing storage warehouse. The area contains solid waste
consisting of pesticide residues and by-products. The waste is
overlain by approximately eight feet of compacted clay fill.
The ground surface is primarily covered with reinforced
concrete.
-------
-16-
AREA 11
(Trash Staaina Area)
Area 11 consists of intermixed soil and waste underlying the
current trash staging area. The intermixed soil and waste
consists of pesticide by-products and is overlain by
approx~ately four feet of compacted clay fill. The surface is
covered with reinforced concrete except for a small portion
along the southern and eastern edges, which is bare ground. The
est~ated volume of contamination in Area 11 is 1,000 cubic
yards.
5.0
SUMMARY OF SITE RISKS
CERCLA directs the Agency to conduct a baseline risk assessment
to determine whether a Superfund Site poses a current or
potential threat to human health and the environment in the
absence of any remedial action. The baseline risk assessment
provides the basis for determining whether or not remedial
action is necessary and the justification for performing
remedial action.
5.1
CONTAMINANTS OF CONCERN
The majority of the wastes and residues generated by production
operations at the facility have been managed, treated, and
disposed of on-site throughout the Site's history. The
contaminated areas of concern are the eleven former waste
management areas where these waste and residues were disposed.
Ten of these areas will be addressed in Operable Unit Two. The
chemicals measured in the various environmental media in the
Remedial Investigation were evaluated for inclusion as chemicals
of potential concern in the risk assessment by application of
screening criteria. The criteria which resulted in elimination
of chemicals included: Site contaminant concentrations below
background concentrations; measurements below quantitation
limits; a combination of low toxicity and low concentration or
low persistence and low concentration and low frequency of
detection.
Separate li8t8 of chemicals of potential concern were identified
for each of the past waste management areas. Typically, the
chemicals of concern for each site area include high molecular
weight chlorinated pesticides (e.g., DDT, gamma-SHC),
site-manufactured pesticides (e.g., atrazine, simazine), and
volatile solvents (e.g., chloroform, xylenes). The media of
concern for this operable unit is contaminated soil. The
maximum and minimum concentrations of analytes found in the
subsurface soil area-wide at the Clba-Geigy Site are contained
in Table 4-1. Since Area 2, the eastern portion of Area 3 and
Area 9 may have surficial contamination, they were evaluated for
the direct contact exposure route. The exposure point
concentrations, used to evaluate the direct contact pathway, for
Area 2, the eastern portion of Area 3 and Area 9 are contained
in Table 5-1.
-------
Chemical
Pesticides
Alpha-SHC
Beta-BHC
Gamma-SHC
DDD
DDS
DDT
Ametryn
Atrazine
Chlorobenzilate
Chloropropylate
Cyanazine
Diazinon
Galecron
Methidathion
Metalochlor
Prometon
prometryn
Propazine
Simazine
Terbumeton
Terbutryn
Tolban
Other Organics
2,4-Dichorophenol
Nitrobenzene
1, 24-Trichlorobenzene
2,4,6-Trichloropheno1
Table 5-1
Bxposure Point Concentrations for Areas 2,
Bastern Portion of Area 3 and Area 9
GealDetric Mean
of Surface Soils
in Area 2
C8g/kg) a
82.1
56.8
73.4
0.2
63.0
166.0
3.0
0.3
0.9
0.7
147.0
Gea8etric Mean
of Surface SOils
in the BaBteru
Part of Area 3
C8g/kg) a
14.4
3.2
2.4
16.1
9.6
8.4
0.1
2.6
2.1
0.4
0.1
0.1
0.1
0.2
0.1
0.1
0.1
0.1
18.6
1.4
0.3
Geo8etric Mean
of Surface SOils
Area 9
C8g/kg) a
96.1
21.6
5.4
0.5
0.3
0.4
0.6
10.0
0.9
21.4
0.1
0.4
0.8
-------
Table 5-1
continued
Bzposure Point Concentrations for Areas 2,
Bastern Portion of Area 3 and Area 9
~Ical
Gec8Btr1c IIean
of surface Soils
ia Area 2
(llg/kg) 8
Gec8Btric IIean
of surface Soil.
ia the BasterD
Part of Area 3
(llg/kg) 8
Gea8Btr1c IIean
of surface Soils
Area 9
(llg/kg) a
IIetals
Lead
96.0
- - Chemical i8 not a contaminant of concern for thi8 area.
~he geometric mean i8 not con8idered to be an appropriate repre8entative of the expo8ure point
concentration. The Ri8k Guidance for Superfund, December 1989 (RAGS), 8pecifie8 that the
reasonable maximum exposure (RHB) concentration, i.e. 95th percent upper confidence limit of
the arithmetic mean be used a8 the exposure point concentration. The Ciba-Geigy risk
a8sessment predates RAGS and therefore does not use the RMB to represent exposure point
concentrations.
-------
-19-
The exposure concentrations represent a geometric mean of data
collected from both surface and subsurface samples and
therefore, the data in Table 5-1 does not necessarily reflect
land surface concentrations.
5.2
EXPOSURE ASSESSMENT
Whether a chemical is actually a concern to human health and the
environment depends upon the likelihood of exposure, i.e.
whether the exposure pathway is currently complete or could be
complete in the future. A complete exposure pathway (a sequence
of events leading to contact with a chemical) is defined by the
following four elements:
.
A source and mechanism of release from the source,
A transport medium (e.g., surface water, air) and
mechanisms of migration through the medium,
The presence or potential presence of a receptor at the
exposure point, and
A route of exposure (ingestion, inhalation, dermal
absorption) .
.
.
.
If all four elements are present, the pathway is considered
complete.
An evaluation was undertaken of all potential exposure pathways
which could connect chemical sources at the Site ~ith potential
receptors. All possible pathways were first hyPOthesized and
evaluated for completeness using EPA's criteria. Three current
potentially complete exposure pathways and two future exposure
pathways remained after screening. The current pathways
represent exposure pathways which could exist under current Site
conditions while the future pathways represent exposure pathways
which could exist, in the future, if the current exposure
conditions change. Exposure by each of these pathways was
mathematically modeled using generally conservative assumptions.
The current pathways arel
.
inhalation by nearby residents of contaminated dust
particles from the past waste management areas with
8U8p&Cted surficial chemicals (areas 2, eastern portion
of area 3 and area 9);
inhalation by nearby residents of volatile chemicals
from subsurface sources in the past waste management
areas; and
.
.
ingestion of venison by local hunters from deer feeding
in vegetated areas of the floodplain.
-------
-20-
The future pathways are:
.
direct contact by Site workers with surface soil in the
three areas which may have surficial contamination
(Area 2, eastern portion of Area 3, and Area 9); and
ingestion of contaminated groundwater.
o
The exposure point concentrations for each of the chemicals of
concern and the exposure assumptions for each pathway were used
to estimate the chronic daily intakes for the potentially
complete pathways, with the exception of the groundwater
pathway. The chronic daily intakes were then used in
conjunction with cancer potency factors and noncarcinogenic
reference doses to evaluate risk.
The groundwater at the Ciba-Geigy Site currently contains
concentrations of the Site contaminants at levels which would
pose an unacceptable risk to human health if the water was being
used for human consumption. However, the surficial aquifer is
no longer being used as a source of potable water at the
Ciba-Geigy plant. Alao the ongoing groundwater extraction and
treatment system is capturing the contaminated groundwater. As
a result, this is not a current complete exposure pathway. The
former waste management areas are the major contributors to the
contaminated groundwater.
The future groundwater exposure pathway was evaluated by
comparing soil concentrations with health-based soil cleanup
levels~ The health-based soil cleanup levels were calculated
using groundwater models, to assure that drinking water maximum
contaminant levels(KCLs), as established under the Safe Drinking
Water Act or health-based levels would not be exceeded in the
groundwater as a result of contaminants leaching through the
soil. As with all models, certain assumptions apply. At the
Ciba-Geigy Site, some of the wastes extend to or near the
groundwater surface while other areas have a significant amount
of uncontaminated clay beneath the waste. As a result, two
models have been applied to the areas of contamination. The EPA
health-baaed subaurface soil cleanup levels are based on either
the Pestan or Summers models, which are used to estimate
groundwater contaminant concentrations resulting from migration
of contAmfftA'1ta through the soil column. The Pestan and Summers
Models incorporate Site-specific aquifer characteristics and
chemical-specific soil-water partition coefficients. The pestan
model was used in areas where an uncontaminated zone exists
between the contaminated soil and the groundwater surface (Areas
2,3,5,6,7,10 and 11). The Summers model was used in areas where
contamination has extended to or is near the groundwater (Areas
1,4 and 9).
-------
-21-
The major assumptions about exposure frequency and duration that
were included in the exposure assessment were:
5.3
o
For the ingestion of venison scenario, it was assumed
that a local hunter kills one deer per year and that
the venison yield from the deer is 44 kg. This
quantity of venison was conservatively assumed to be
consumed annually throughout a 70-year lifetime.
For the inhalation of ambient air scenario it was
assumed that an individual lives in the nearest 3
residence (2.5 km from the Site) and inhales 20 m of
air per day over a 70-year lifetime. All particulate
matter at the exposure point was assumed to be
respirable and delivered to the pulmonary region of the
lung. The chemicals of concern were assumed to be 100
percent bioavailable.
.
.
For workers the direct contact with contaminated soil
scenario, it was assumed that a worker ingests 50 mg of
soil per day spent at the Site. Addition~lly, it was
assumed that the inhalation rate was 20 m /day. It
was assumed that the worker is present at the Site 250
days a year. The assumed exposure duration is for 25
years.
In all scenarios a standard body weight of 70 kg was
used.
.
TOXICITY ASSESSMENT
Toxicity values are used in conjunction with the results of the
exposure assessment to characterize site risk. EPA has
developed critical toxicity values for carcinogens and
noncarcinogens. Cancer potency factors (CPFS) have been
developed by EPA's Carcinogenic Assessment Group for estimating
excess lifetime cancer risks associated with exposure to
potentially carcinogeniclchemicals. CPFs, which are expressed
in units of (mg/kg/day)- , are multiplied by the estimated
intake of a potential carcinogen, in mg/kg/day, to provide an
upper-bound estimate of the excess lifetime cancer risk
associated with exposure at that intake level. The term "upper
bound" reflects the conservative estimate of the risks
calculated from the CPF. Use of this conservative approach
makes underestimation of the actual cancer risk highly
unlikely. Cancer potency factors are derived from the results
of human epidemiological studies or chronic animal bioassays to
which animal-to-human extrapolation and uncertainty factors have
been applied. The CPFs for oral ingestion and inhalation
exposure to the contaminants of concern at the Site are
contained in Tables 5-2, and 5-3 respectively.
-------
Table 5-2
HEALTH EFFECTS CRITERIA JCR ORAL EXPOSUIIE TO CHE~!:ALS OF CONCERN
EPA/CAG
lIeference Dose C.ncer
(IIfD) uncertainty Pouncy F.ct:lr IIeig"t c~
C"emic'l (111;/ltg/d.y) F,ctor (I) Source (b) (mg/k9/dly).1 Evidence (c)
Acetone 1 E. 1 1,000 III! S
Ametryn 9E.3 1,000 11115
Anll ine 5. 7E'3 B2
ArsenIC 1. OE . 3 EPA 1.~ A
Atruine 5E'4. 1,000 1111 S.. C
Benzene - ..e . IRIS 2.9E'2 A
Ilpha'SHC 6.3 B2
beta'BHC 1.8 C
gl/lllll'BHC 3E-' 1,000 11115 1.3. B2.C
Carbon disulfide 1E.1 100 11115
CIII orobenzene 3E-28 1,000 HEA
Chlorooenzi late EPA8.. 5.5E'2 B2
Chloroform 1.0E'2 1,000 11115 6.1E'3 82
Chloroproovlate (d) IE'2 1,000 C IU-GE IGY
Chromil.lll (II 1 100 11115
Chromil.lll vi 5E-3 500 11115
Co~r 3.1£,2 HEA
Cyanazine 2.0E-3 300 11115
Cyanide (as Hydrogen Cyanide) 2.0E'2 100 11115
DI.zinen 9.0£-4. 10 EPA
ODD
DOE
DDT 5E-' 100 11115 3.4.E-18 82
1,2'Diclllorobenz~ 9E-2 100 HEA
1.'-DichlorObenZ~ 1.0£-1 1,000 itA 2.4.E-2 B2
2,'-Dichlor~enol 3E-3 100 11115
2,4.'Dinitrotoluene EPA 0.68 B2
2,6'Dinitrotoluent ORNL '.83
Ethyloenzene 1E- 1 1,000 11115
G.lecron NAS 9.4E-1 B2
'.ead 6E-' MCLG
AethidathiQl'l 1E-3 100 11115 C
Methylene chloride 0.06 100 IRIS 7.5E'3 82
MetOI.chlor 1 . 5E - 1 100 11115 C
Nitrocenzene 5E-4. 10,000 11115
Prometcn '.5E-2 1,000 11115
Prometryn 'E-3 1.,000 tillS
ProOlZ i ne 2E-2 300 11115
Sillluine 5E-3 1,000 IRIS
S irnetryn -.. ..-
TerbunetQl'l (d) 7.5£-2 100 CI8A-G£IGY
Terbutryn 1.oe-] 100 11115
TerCUthylazine (d) 3.5E-] 100 CIIA-GEIGY
Tetr.cllloroethyl~ 1.0E-2 1,000 11115 5.1E-2. B2
Tolbln (d) 2.5E-] 100 C!BA-GEIGY
Toluene ].oe-1 100 11115
1,2,4.Trichloro~zene 2.oe-2 1,000 11115
2,1, ,6' Tr i cp,(orOpflenol -.. 2.0E-2 82
)(,/1_5 (1IIIAed) 2 100 1111 S
(,) uncertainty factor. U88d to develop reference dOses conai,t of nultiples of 10, each flctor r~resenting a
specific Irel of unc.rtainty inherent In tfte dltl IVlillble. The standard uncertlinty factors include:
. A 10.fola factor 108CCOUnt for the variltion in sensitivity .-on; the members of tile human POPUlltion;
. A 10-fola factor to accownt for the uncertlinty in extrlpolating ani~1 dlta to the clse of humans;
. A 'O.fOld factor to accownt for uncertainty in extrapolating fro. less tllan chronic NOAELs to chronic
NOAELs and;
. A 10.fola flctor to accownt for the uncertlinty in extrapolating from LOAELs to NOAELs.
(b) Source of lIeference OOS": IRI5. cheaical files of the Integrated .islt Inform8tion Syst~: MCLG . MaxilllUlll
Cont8lllinant LevII Goal; HEA . HIIltn Effects Allessment; "A . "111tll AdVisory; MAS. National ACademy of
Science; ORNL . Oalt Ridge .Itiona' Laborltories.
(C) IIeignt of Ividence CllslificatiQl'l ICII81111 for carcinogens: A--~ Clrcil"109en, lufficient evidence from human
epidellliological Itudi..; 11"proOltlle M~ Clrcinogen, I isited Ividencl frOll ~i08lliologicll studies .nd
ldeQUlte evidence fro. ani..1 studi..; 12..PrOOllble MlAllln Carcinogen, ina"equlte Iyidence from epidemiological
studi.. Ind 8dlquete ev;c.nce fro. eni..' studies; C"POSlible M\III8I"I Clrcif\09I1"1, I i.i ted evidenCe in It\i..IS
in the Ibsence of hU8ll"l dlta; O--.ot C'lslifilO al to h~ carcinogenicity; and E--Evidence of
NonclrcinogeniCity.
'a) Acceptatlle Clily inta.e derived by Cibl-Geigy from the results of unpuclisned studiel ptrfo~ by Ciba'Gelgy.
8 . Rlvi... pending.
.. . Eatra lafety flCtor of 10 Mel tpplied to account for polsible carcinogenicity (verDlI c~ication .
Ted FarDer '9881
... . Mellth end Env'r~ta' Effects Profl'l (NEEP) 19&4 and verba\ communication' loe "cG~y '988.
-------
:-able 5-3
HEALTH EFFECTS CRITERIA FOR INHALATION eXPCSURE TO CHEMICALS OF CONCERN
EPA/CAG
Referencl Dose C.l'ICer
CUD) uncertainty Pouncy F,Ctor "'"9M of
C!'It!
-------
-24-
Reference doses (RfDs) have been developed by EPA for indicating
the potential for adverse health effects from exposure to
chemicals exhibiting noncarcinogenic effects. RfDs, which are
expressed in units of mg/kg/day, are estimates of lifetime daily
exposure levels for humans, including sensitive individuals.
Est~ated intakes of chemicals from environmental media can be
compared to the RfD. RfDs are derived from human
epidemiological studies or animal studies to which uncertainty
factors have been applied (e.g., to account for the use of
animal data to predict effects on humans). These uncertainty
factors help ensure that the RfDs will not underestimate the
potential for adverse noncarcinogenic effects to occur. The
RfDs for oral ingestion and inhalation exposure to the
contaminants of concern at the Site are contained in Table 5-2,
and 5-3 respectively.
5.4
RISK CHARACTERIZATION
Human health risks are characterized for potential carcinogenic
and noncarcinogenic effects by combining exposure and toxicity
information. Excessive lifetime cancer risks are determined by
multiplying the estimated daily intake level with the cancer
potency factor. These risks are probabilities that are
generally expressed in scientific nOgation (e.g., lxlO-6). An
excess lifetime cancer risk of lxlO- indicates that, as a
plausible upper bound, an individual has a one in one million
additional (above their normal risk) chance of developing cancer
as a result of site-related exposure to a carcinogen over a
'O-year lifetime under the assumed specific exposure conditions
at a Site.
The AgeniY conside6s individual excess cancer risks ~n the range
of lxlO- to lxlO- as protective~ however the lxlO- risk
level is generally used as the point of departure for setting
cleanup levels6at Superfund sites. The point of departure risk
level of lxlO- expresses EPA's preference for remedial
actions that result in risks at the more protective end of the
risk range.
Potential concern for noncarcinogenic effects of a single
contaminant in a single medium is expressed as the hazard
quotient (KQ) (or the ratio of the estimated intake derived from
the contAminant concentration in a given medium to the
contaminant.'s reference dose). A HQ which exceeds one (I)
indicates that the daily intake from a scenario exceeds the
chemical's reference dose. By adding the HQs for all
contaminants within a medium or across all media to which a
given population may reasonably be exposed, the Hazard Index
(HI) can be generated. The HI provides a useful reference point
for gauging the potential significance of multiple contaminant
exposures within a single medium or across media. An HI which
exceeds unity indicates that there may be a concern for
potential health effects resulting from the cumulative exposure
to multiple contaminamts within a single medium or across media.
-------
-25-
The health risks resulting from exposure to the current pathways
are as follows: the upper bound excess lifetime cancer risk
assoc~ated with inhalation of airborne particulate matter was
1x10- ; the cancer risk associated with inhalation of
volatioized chemicals from the combined source areas was
3x10- ; and the lancer risk associated with ingestion of
venison was 2x10- . None of the non-carcinogenic chemicals
of potential concern exceeded a hazard quotient of one (1).
The future pathway based on groundwater contamination resulting
from leaching of contaminants from the soil was evaluated by
comparing the health-based soil cleanup levels and the soil
concentration of the contaminants of concern in the former waste
management areas. Table 5-4 contains this comparison. The soil
cleanup levels represent the residual soil concentrations that
would not exceed the accePiable groundwater human health
concentrations for a 1x10- risk level as a result of the
contaminants leaching through the soils to the groundwater.
The comparison of the health-based cleanup level concentrations
with the actual soil concentrations indicate that the soils in
the former waste management areas, with the exception of Areas
5, 10 and 11, contain concentrations of Site-related
contaminants which exceed the health-protective soil levels.
The future risks associated with direct contact by workers with
surficial soils in Area 2, the eastern portion of Area 3 and
Area 9 are presented in Table 5-5. These areas may have
surficial contamination. The risk levels in this table
represent the cumulative risks associated with the ingestion and
inhala~ion exposure routes. Tie cumulat~ve risk levels are
within the risk range of 1x10- to 1x10- for Areas 2 and
3. The risk level for Area 9 (1.2 x 10-4) slightly exceeds
the lower end of the acceptable risk range. The cumulative HOs
for the direct contact pathway do not exceed unity for the three
areas of concern.
The potential current exposure pathways are not producing an
unacceptable level of risk and consequently will not drive the
remediation of the former waste management areas. However,
since the subsurface soils are either currently contributing or
could potentially contribute in the future to unacceptable
levels of groundwater contamination, this pathway will dictate
the remediation of the contaminated subsurface soils. ~though
the surface 80il is not currently well characterized, the direct
contact pathway could potentially require the remediation of
surface soils, especially in Area 2, the eastern portion of
Area 3 and Area 9.
-------
Table 5-4
Caaparison of 8011 Concentrations of selected coot_inants with
Health-Based SoU Concentrations (8I}/kg)a
Health-Based b
Cht!lDical COncentration (8B8II/8II.1Il8u8)
concentration
(S~B ~l)
Area Area Area Area
1 41. 4C 9
Alpha-BHC 4.3 96.1/2910
Beta-BHC 16.8 21.6/571
Lindane 1.0 5.4/753
Delta-BHC 2.7
DDT 5034 106/2020 10.2 0.4/1.4
DDD 6758 22.0/669 26.7 3.4 0.5/0.8
DDE 16527 25.7/271 17.8 0.3/0.7
Dlazlnon 9.5 0.6/26.6 179 0.9/47
Chlorobendlate 209 1.5/6.3 10/80
arhe Boil health-based concentrations are baBed on health-protective number. for the inve.tion of
groundwater pathway. Depending on whether the Boil contamination extended to the vroundwater Burface
either the Summers or Pestan model was used. The Summers model was uBed for are.. in which the
contamination was at or near the groundwater Burface (Areas 1, 4 and 9). The PeBtan model wa. used for
the remaining area8 (Area8 2, 3, 5, 7, 10 and 11) where the contamination did not reach the groundwater
Burface.
b .
One entry indicates that only one sample was collected 1n this area.
- - Chemical i8 not a contaminant of concern for this area.
-------
Table 5-4 (Continued)
~iBOn of Soil OoDcentratloos of Selected Oontaalnants with
Health-Based Soil ConcentratIons (8}/Ir:g)a
Chemical Health-Based ConcentratIon (8ean/IIIIJIl8u8)b
Concentration
(Peaten Mode I)
Area Area Area Area Area Area Area Area
2 3A 38 3C 3D 3E 3-F111 Area 3-eooUng Ditch
Alpha-BHC 156 5.1/126 38/4370 3.5/21.2 274/1010
Beta-BHC 152 15.2/751 47.8/228
Lindane 37 3.7/218 3.0/6.4
De1ta-SHC 154
DOT 7500 73.4 7.0 216/3780 86/1000 46.8/190 2.5/12
ODD 7500 82.1 35.2 182/8590 273/3020 63.4/1160 10.3/86.5
DOE 172500 56.8 31.3/8410 87.5/1930 32.1/300 5.7/21.3
Diazinon 10 755/786 1.8/5.0 0.3/30.1 0.5/1.0 0.2/0.4
Ch10robenzilate 340 63/650 - - 0.5 3.2/488 3.7/7.2
B.rhe .011
pathway.
model was
(Areas 1,
reach the
health-based concentrations are baaed on health-protective numbers for the lDg88tion of groundwater
Depending on whether the soil contamination extended to the groundwater .urface either the Summer. or Pe.tan
used. The Summers model was used for areas in which the contamination was at or near the groudwater Bur face
4 and 9). The Pest an model was used for the remaining (Areas 2, 3, 5, 7, 10 and 11) where the contamination
groundwater surface.
b
One entry indicates that only one sample was collected in this area.
- - Chemical is not a contaminant of concern for this area.
-------
Table 5-4 (Continued)
008parison of Soil Concentrations of Selected Contaalnants with
Health-Based So11 Concentrations (l8g/kg)a
Chel8ical Health-Based Concentration (8ean/8la.l8J8)b
Concentration
(PeBtan IIodel)
Area Area Area Area Area
5 6 7 10 11
Alpha-BHC 156 123/601
Beta-BHC 152
Lindane 37
Delta-BHC 154
DDT 7,500 146/2050 0.1 90.8
DDD 7,500 134/535 0.2 223
DDE 172,500 60.3/181 1.9
Diazinon 10 7.1/680 38/48 0.1
Chlorobendlate 340 0.8/8.2
arhe 80il health-based concentrations are based on health-protective numbers for the 1Dge8tion of groundwater
pathway. Depending on whether the soil contamination extended to the groundwater Burfac. either the Summers or Pest an
model was used. The summers model was used for areas in which the contamination was at or near the groundwater Burtac.
(Areas 1, 4 and 9). The Pestan model was used for the remaining (Areas 2, 3, 5, 7, 10 and 11) where the contamination
did not reach the groundwater surface.
b
One entry indicates that only one sample was collected in this area.
- - Chemical is not a contaminant of concern for this area.
-------
'1'01. 5-5
8~ of Rillk for t;he Future Wormr bposure to
SUrficial SoUe in Area 2. Ba8tern Portion of Area 3 aDd Area 9
Cbealcal Sit. Are. 0 f Concern
2 Eastern 3 9
Alpha-BHC 1.68-6 1.11:-4
Beta-SHC 1.08-6 6.91:-6
Gamma-SHC 5.68-7 1.2E-6
DDD 3.5E-6 6.98-7 2.18-8
DDE 3.48-6 5.88-7 1.81:-8
DDT 4.4E-6 5.18-7 2.41:-8
Total Risk
1.1B-5
2.08-5
1.21:-4
-- Chemical is not contaminant of concern for this area.
-------
-30-
5.5
EN'lIRONMENTAL RISK
Each of the source areas are presently either covered with fill
or fenced and therefore are not easily accessible to certain
terrestrial species. For this reason the source areas are not
expected to have toxic effects on those terrestrial an~als at
this t~e. However, the ecological assessment indicates that
the Site may have toxic effects on certain plant species, as
well as robins and shrews in the areas of concern in the
future. The selected remedy based on human health will
eliminate the potential for toxic effects since the
environmental exposure pathways will not exist. The
environmental impact for the bottom dwelling aquatic communities
in Johnson Creek, the floodplain, and the Tombigbee River will
be further evaluated in Operable Unit 13.
5.6
CLEANUP LEVELS
The September 1989 ROD for Operable Unit 11, Groundwater
Remediation, addresses the contaminated groundwater exposure
pathway. The cleanup levels of the currently operating
groundwater pump and treat system which ensures that
concentrations of contaminants in the groundwater do not exceed
unacceptable risk levels for any future consumers of this water
are contained in Table 5-8. The cleanup levels for groundwater
in deep soil treatment areas are also contained in Table 5-8.
The groundwater cleanup levels in the deep soil treatment areas
have been generated to ensure localized isolation and treatment
of contaminated groundwater which exceeds the healt~-based
groundwater cleanup levels established at the 1x10- risk
level. This is consistent with areas requiring no localized
deep soil treatment.
The ROD for Operable Unit 11 did not address the sources of
contamination. Addressing the contamination source will
decrease the time required to pump and treat. Cleanup levels
for the contamination source (the subsurfac~ soils) for
groundwater protection are based on a 1x10- risk level for
carcinogens and a hazard quotient of 1 for noncarcinogens.
Setting the cleanup levels for subsurface soils at the 1xlO-4
risk level i8 consistent with the NCP's requirement fOf
establish~g cleanup levels within the 1x10- to 1x10-
range. Th1. cleanup level provides an acceptable exposure level
that is protective of human health and the environment in an
isolated industrial setting. Cleanup levels for contaminated
surface soil are based on a worker exposure scenario and assume
a commercial/industrial land use. These levels are based on the
ingesiion and inhalation exposure routes and represent a
1x10- risk level for carcinogens and a hazard quotient of 1
for noncarcinogens. The cleanup levels for groundwater and
soils are listed in Table 5-8 and 5-9 respectively.
-------
-31-
TABLE 5-8
The following groundwater cleanup levels are being applied at
the property boundary for groundwater leaving the Site to ensure
that any future groundwater consumers will not be exposed to
unacceptable concentrations of Site-related chemicals in the
groundwater. The concentrations presented represent either the
regulated Maximum Contaminant Level (MCL) or the Minimum
. Detection Level for the constituents listed.
GROU1I1DWATBR CLBAIItJP LEVELS
AS PROVIDBD Iii ROD ADDRESSIIiG OU'l
Contaminants
Cleanup
Goal (ug/l)
Aniline
Arsenic
Benzene
Alpha-BHC
Gamma-BHC
Carbon Tetrachloride
Chlorobenzene
Chloroform
Cresols (m-p-)
Methyl Ethyl Ketone
Napthalene
Toluene
10
50
5
.05
0.2
5
5
5
10
10
10
2000
The following groundwater cleanup levels would be applied to any
groundwater withdrawal wells installed within the RCRA defined point
of compliance or within the areas identified for each of the eleven
identified areas. The withdrawal wells would be installed in areas
where subsurface soil cleanup levels were not achieved.
GROUJIDIiM'BR CLBAIItJP LEVELS FOR DBBP SOIL TRBATJIBIi'l' AREAS
Compound
alpha-BHC
beta-BHC
Lindane
delta-BHC
DOT
DDD
DDE
Diazinon
Chlorobenzilate
Cleanup
Level (ug/l)
0.6
2.0
0.2
0.2
10.0
10.0
10.0
6.0
140.0
-------
-32-
TABLE 5-9
DIRBC'l' COHTAC'l' SOIL CLBAHOP LEVELS POR OU.2
AT THE ClBA-GEIGY SITE
The following table provides the direct contact cleanup levels.
These levels will be applied to the top 12 inches of soil
throughout the areas of contamination.
ContAm;nAnt
1B-6 Risk
Direct Contact Pathway
(ag/kg)
DDT
DDD
DDE
Alpha-BHC
Beta-BHC
Delta-SHC
Gamma-SHC
*Chlorobenzilate
*Diazinon
17
24
17
1.0
3.0
2.0
4.0
39,922
1,796
SUBSURFACE SOIL CLBAIIOP LEVELS FOR OU.2
DUB TO GROUHDWATBR I.GESTIO. PATIIWAY
The subsurface soil
1E-4 Risk Level and
be applied to Areas
applied to Areas 2,
Contaminant
cleanup levels have been generated at the
are presented below. The Summers Model will
1, 4 and 9 and the Pestan Model will be
3, 5, 6, 7, 10 and 11.
Summer's
(lDg/kg)
Pestan
(lDg/kg)
DDT
DDD
DDE
Alpha-BHC
Beta-SHC
Delta-BHC
Gamma-BHC
*Chlorobenzilate
*Diazinon
5,034
6,758
16,527
4.0
17
3
1.0
209
10
7,500
7,500
17,250
156
152
154
37
340
10
* This chemical is not considered to be a carcinogen. Therefore, the
cleanup levels do not represent a carcinogenic risk level. The cleanup
level for this chemical represents a concentration which, when combined
with the Site specific exposure assumptions, will yield a daily intake
which does not exceed the chemical's reference dose (RfD). The RfD is
an estimate of the lifetime daily exposure level for humans, including
sensitive individuals, which will not produce adverse health effects.
-------
-33-
Although the contaminants of concern are not the only contaminants at
the Site, they were chosen based on toxicity, mobility and frequency
of detection throughout the Site. It is anticipated that
contaminants at the Site which do not have cleanup levels presented
in this ROD will be reduced to acceptable levels when cleanup levels
are met for the most toxic and most mobile contaminants for which
cleanup levels have been established.
. The groundwater at the Ciba-Geigy Site currently contains
concentrations of Site-related contaminants at levels which wiuld
pose an unacceptable risk (cumulative risk in excess of lxlO- ) to
human health if the water was being used for human consumption.
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.
6.0
DESCRIPTION OF ALTERNATIVES
Nine alternatives for remediation of contaminated soils at the
Ciba-Geigy Site were evaluated in the Feasibility Study Report and
listed in the initial Proposed Plan for the Site. After reviewing
comments received during the initial comment period, the concept8 of
the nine alternatives were reduced to four alternatives based on the
similarities in their technologies. After reviewing the comments
received during the comment period for the Amended Proposed Plan an
additional alternative (number 5) has been included.
6.1
ALTERNA~IVE No.1 - No Action
The no action alternative is carried through the screening process as
required by the National Oil and Hazardous Substances Pollution
Contingency Plan (NCP). This alternative is used as a baseline for
comparison with other alternatives that are developed. Under this
alternative, EPA would take no further action to minimize the impact .
soil contamination would have on the groundwater. Contaminants in
the soil would continue to leach into the groundwater at levels which
would exceed groundwater protection standards. The overall remedial
action levels would not be achieved within 100 years by utilizing
this alternative. There is no cost associated with this alternative
since no additional activities would be conducted.
6.2
ALTERNATIVE No.2 - Containment
This alternative consi8ts of placing a soil bentonite slurry wall
around the perimeter of the area to prevent lateral migration of
contaminants in the groundwater. A multilayered RCRA cap would be
placed over the area to minimize the vertical migration of soil con-
tamination. The area would be revegetated following construction
activities. Soil contamination would not be reduced, but isolated
from the environment by the cap and slurry wall. Institutional
controls (land and groundwater use restrictions) would be necessary
to ensure the integrity of the alternative. Pollowing the
-------
-34-
construction of the cap and slurry wall, the Site would be monitored
to verify the effectiveness of the remedy. The overall remedial
cleanup levels as defined in operable unit one, would not be achieved
within 100 years by utilizing this alternative. The alternative
could be constructed in 48 months. The present worth cost of this
alternative, including operation and maintenance, is estimated to be
$23,400,000.
Elements COJIIIDOn to AI ternati ves 3, 4 and 5
Alternatives 3, 4 and 5 involve the excavation of all soil which
exceeds the health-based cleanup levels. Although the actual cleanup
levels are not Applicable or Relevant and Appropriate Requirements
(ARABs), they were established, in part, to ensure that the Federally
regulated drinking water standards (ie., Maximum Contaminant Levels),
which are ARARs, are not exceeded by the leaching of contamination
from the soils into the groundwater. Section 121 (d)(4)(C) of CERCLA
provides that an ARAR may be waived when compliance with an ARAR is .
technically impracticable from an engineering perspective. The
waiver may be granted in the following alternatives should
engineering methods necessary to excavate the contaminated soil to
the cleanup levels be technically impracticable. EPA has concluded
that it is technically impracticable and less cost effective in this
case to excavate to depths in excess of 20 feet. This is based on
the determination that excavating beneath depths of 20 feet would
pose a potential for cave-in of the excavated area. Therefore, the
cost of excavation due to the implementation of measures to minimize
this hazard would be extremely high compared to standard excavation
cost.
For areas where it is technically impracticable to achieve the
remediation level, insitu technologies (i.e., in-situ vacuum
extraction, in-situ soil washing, and in-situ bioremediation) would
be evaluated during the remedial design and implemented if proven
feasible. Institutional controls (i.e., land and groundwater use
restrictions) that are determined to be necessary to preclude the
potential for exposure to the subsurface contaminated soil would also
be implemented. In addition, the remaining alternatives may require
a portion of a warehouse in Area 10 to be temporarily removed prior
to excavation.
ALTERHATrvE No.3 - Removal. Stabilization/Solidification,
and On-Site DisDOsal
This alternative consists of the excavation of contaminated soil and
sludge within the Site until the established cleanup levels are
reached or until excavation becomes technically impracticable from an
engineering perspective (see section 6.2, Elements Common to
Alternatives 3, 4 and 5). The excavated material would be
stabilized/solidified. After stabilization/solidification, the
material would be disposed of in an on-site landvault after RCRA LOR
treatment standards, pursuant to a treatability variance, are met.
In accordance with Superfund Land Disposal Restriction (LDR) Guidance
'6A, for herbicides, which are similiar and are applicable to Site
contaminants, a treatability variance requires that the selected
technology must demonstrate a 90-99.9 percent reduction in the
contaminants of concern.
6.3
-------
-35-
Uncertainty exists regarding the effectiveness of stabili-
zation/solidification of material contaminated with elevated
concentrations of organic contaminants. Therefore, treatability
studies would be conducted to determine the effectiveness of this
alternative in meeting the legislated treatment standards.
Stabilization/solidification would be utilized for soils where it is
proven effective in reducing the contaminated soil concentrations to
. Land Disposal Restrictions (LDRS) treatability variance levels. The
NCP establishes a presumption that treatment to the legislated
standards based on the Best Demonstrated Available Technology is
generally inappropriate for CERCLA contaminated soil and debris (55
FR 8758-62, (March 8, 1990». Therefore, compliance with the land
disposal treatment standards would be achieved pursuant to a
treatability variance for CERCLA contaminated soil and debris which
would be granted upon ROD signature. The landvault would be
designed in accordance with applicable RCRA regulations. The areas
would be backfilled following excavation activities. Following Site
remediation, the excavated areas would be vegetated. If the'
subsurface excavation levels are not achieved because of technical
impracticability, institutional controls (i.e., land and groundwater
use restrictions) would be necessary to restrict exposure to the
contaminated subsurface soil. The overall remedial action levels
would not be achieved within 100 years 'by utilizing this
alternative. Alternative 3 could be constructed in 48 months.
Approximately 127,000 cubic yards of material would be
stabilized/solidified. The present worth cost of this alternative is
estimated at $41,250,000.
6.4
ALTERNATIVE No.4 -
Removal. On-Site Thermal Treatment. and
On-Site DisDosal
This alternative consists of the excavation of contaminated sludge
and soil within the Site until the established cleanup levels are
reached or until excavation becomes technically impracticable from
an engineering perspective (see section 6.2, Elements Common to
Alternatives 3, 4 and 5). The majority of the excavated material
would be treated on-site by thermal treatment. Treatability studies
would be conducted to determine the effectiveness of
solidification/stabilization of soils with low levels of
contamination. Stabilization/solidification would be utilized for
soils where it is proven effective by these treatability studies in
reducing the contaminated soil concentrations to LDR treatability
variance levels.
The contaminated soil may require pre-treatment to remove debris
(i.e., drums, scrap metal, construction rubble etc.) present before
the thermal treatment process. At the time of excavation during the
remedial activities, the debris would be removed from material that
is required to be treated.' If drums are encountered, the contents
would be removed from the drums and it would be tested to determine
if it is hazardous waste. A determination would be made based on a
method to be detailed in the remedial design phase of the project as
to the hazardous or non-hazardous nature of the debris. If the
debris is determined to be of a non-hazardous nature, it may be
decontaminated and separated into a category of materials that can
-------
-36-
be disposed of off-site and/or recycled. Debris that is determined
to be of a hazardous nature would be treated in an appropriate manner
to be determined during the remedial design.
The soils with low levels of contamination would undergo
stabilization/solidification. The soils with high levels of
contamination would be ther.mally treated. The soils to be thermally
treated would be blended in a tank which meets the definition of a
tank in Section 260.10 of the Code of Federal Regulations (40 CFR).
The purpose of the blending is to achieve a homogeneous mixture prior
to thermal treatment to ensure proper thermal treatment operations
and to comply with operating conditions determined in the trial
burn. Ash from the thermal treatment process and any
solidified/stabilized material would be disposed of in a landvault
after RCRA LDR treatment standards, pursuant to a treatability
variance, are met. In accordance with Superfund LDR Guidance #6A,
for herbicides, which are similar and applicable to Site
contaminants, a treatability variance requires that the selected
technology must demonstrate a 90-99.9 percent reduction in the
contaminants of concern. Following excavation activities, the areas
would be backfilled and revegetated.
If the excavation levels are not achieved because of technical
impracticability, this alternative would rely on natural flushing of
the contaminated soi18 beneath a depth of 20 feet and remediation of
the groundwater by the existing pump and treat system. Overall
remedial action levels would not be achieved within 100 years by
utilizing this alternative. This alternative could be implemented in
7 years. The present worth cost of this alternative, including
operation and maintenance, would range from $90,000,000, if
solidification of soils with low levels of contamination is proven
effective, to $116,250,000 for complete incineration of all of the
contaminated material.
6.5
ALTERNATIVE No.5 - Removal. On-Site Thermal Treatment. and
On-Site DisDosal
This alternative is identical to Alternative 4 with the following
additions. Thermal treatment in this alternative may a180 include a
pre-treatment phase prior to the main thermal treatment process.
Three potential pre-treatment options includes solvent extraction,
followed by liquid injection incineration~ low temperature thermal,
followed by treatment of the desorbed volatile organics/air mixture;
and critical fluid injection, followed by liquid injection
incineration. These options for pre-treatment would be evaluated
during design to determine if the main thermal treatment process
and/or cost effectiveness can be enhanced while still meeting
levels pursuant to the treatability variance. If any of the
technologies are proven to enhance cost effectiveness or the main
thermal process, it would be used.
Under certain circumstances, the pre-treatment option could totally
replace the main thermal treatment process. If any of the
pre-treatment technologies are proven to be more effective in
reducing the contaminant concentrations in the soil and is more cost
-------
-37-
effective, it would be used instead of the main thermal treatment
process. Pre-treatment technologies that were not effective in
reducing contaminated soil concentrations to levels pursuant to the
treatability variance or did not enhance cost effectiveness would not
be utilized.
Stabilization/solidification would still be the primary technology
for the remediation of soils with lower contaminant levels.
. Treatability Studies would be conducted during design to determine
the maximum soil concentrations that can be treated via
stabilization/solidification and still achieve LDR variance levels.
However, a new, innovative chemical treatment technology,
dechlorination may be tested during design and if found effective,
may be used instead of solidification for some low level soils.
Dechlorination uses a base (i.e., sodium hydroxide) and an organic
source of hydrogen and a catalyst to accomplish reductive
dehalogenation of halogenated materials. If dechlorination is proven
to be more effective in reducing the contaminant concentrations in
the soil and is more cost effective, it would be used instead of the
solidification/stabilization process. If dechlorination is proven
ineffective in reducing contaminated soil concentrations to levels
pursuant to the treatability variance and/or does not enhance cost
effectiveness it would not be utilized.
The results of the treatability studies would be evaluated and the
technologies to be used for remediation of the contaminated soils
would be determined and noted in the 30% Remedial Design Report. EPA
would then issue a public notice in a local newspaper and send a fact
sheet to persons on the mailing list to inform the public of the
technologies proven effective and which are to be implemented.
Ash from the thermal treatment process, any solidified/stabilized
material or any material from the dechlorination process would be
disposed of in a landvault after RCRA LDR treatment standards,
pursuant to a treatability variance granted upon ROD signature, are
met. In accordance with Superfund LDR Guidance t6A,
for herbicides, which are similar and applicable to Site
contaminants, a treatability variance requires that the selected
technology must demonstrate a 90-99.9 percent reduction for the
contaminants of concern.
Following 8zcavation activities, the area would be backfilled and
revegetated. However, under this alternative, if cleanup levels are
not achieved before a depth of 20 feet is reached, extraction wells
combined with isolation walls extending from the land surface to the
top of the Miocene clay and insitu soil flushing would be utilized to
flush contaminants from deep unsaturated soils, thus decreasing the
time required to operate the pump and treat system implemented in
operable unit one. The contaminated groundwater extracted by these
wells will be treated by the currently operating waste water
treatment system. Innovative technologies (insitu vacuum extraction
or insitu bioremediation) may also be used in concert with the soil
flushing approach, if during design they are found to be effective in
-------
-38-
reducing soil concentrations to excavation
controls, such as deed restrictions, would
usage of qroundwater and minimize land use
are achieved.
levels. Institutional
be established to preclude
until all cleanup levels
This alternative could be implemented in 10 years. The present worth
cost of this alternative, including operation and maintenance, would
range from $94,000,000, if solidification of soils with low levels of
contamination is proven effective, to $120,250,000 for complete
incineration of all of the contaminated material.
7.0
SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES
This section of the ROD provides the basis for determining which
alternative provides the best balance with respect to the statutory
balancing criteria in Section 121 of CERCLA and in Section 300.430 of
the NCP. The major objective of the FS was to develop, screen, and
evaluate alternatives for the remediation of Operable Unit Two at the
Ciba-Geigy Site. A wide variety of technologies were identified as
candidates for remediating the contaminated soils at the Site. These
technologies were screened based on their feasibility with respect to
the contaminants present and the Site characteristics. The
technologies that remained after the initial screening were combined
into potential remedial alternatives and evaluated in detail. The
remedial alternatives selected from the screening process were
evaluated using the following nine evaluation criteria:
o
OVerall protection of human health and the environment.
Compliance with applicable and/or relevant Federal or State
public health or environmental standards.
.
o
Long-term effectiveness and permanence.
Reduction of toxicity, mobility, or volume of hazardous
substances or contaminants.
o
.
Short-term effectiveness, or the ~pacts a remedy might have
on the community, workers, or the environment during the
course of Lmplementing it.
D8plementability, that is, the administrative or technical
capacity to carry out the alternative.
o
.
Coat-effectiveness considering costs for construction,
operation, and maintenance of the alternative over the life
of the project, including additional costs should it fail.
Acceptance by the State.
o
.
Acceptance by the Community.
-------
-39-
The NCP categorizes the nine criteria into three groups:
( 1)
Threshold Criteria - overall protection of human health and
the environment and compliance with ARARs (or invoking a
waiver) are threshold criteria that must be satisfied in
order for an alternative to be eligible for selection;
Primary Balancina Criteria - long-term effectiveness and
permanence; reduction of toxicity, mobility, or volume;
short-term effectiveness; implementability, and cost are
primary balancing factors used to weigh major trade-ofts
among alternative hazardous waste management strategies; and
(2 )
Modifvina Criteria - state and community acceptance are
modifying criteria that are formally taken into account
after public comment is received on the proposed plan and
incorporated in the ROD.
The selected alternative must meet the threshold criteria and comply
with all ARARs or be granted a waiver for compliance with ARARs. Any
alternative that does not satisfy both of these requirements is not
eligible for selection. The Primary Balancing Criteria are the
technical criteria upon which the detailed analysis is primarily
based. The final two criteria, known as Modifying Criteria, assess
the public's and the state agency's acceptance of the alternative.
Based on these final two criteria, EPA may modify aspects of a
specific alternative.
(3)
The following analysis is a summary of the evaluation of alternatives
for remediating the Ciba-Geigy Superfund Site under each of the
criteria. A"comparison is made between each of the alternatives for
achievement of a specific criterion.
Threshold Criteria
7.1
Overall Protection of Human Health and the Environment
All of the alternatives would provide protection of human health and
the environment by minimizing or controlling the risk associated with
the contaminated soils through treatment or containment and
institutional controls. In Alternative 1, the currently operating
groundwater pump and treat system would continue operating. However,
contaminant. in the soil would continue to leach into the groundwater
at unacceptable levels. Cleanup levels for groundwater would not be
achieved within 100 years with Alternative 1. Alternative 2 would
isolate the contamination from the surrounding uncontaminated area.
The alternatives involving excavation, (Alternatives 3, 4 and 5),
would minimize the majority of the risk by removing and treating the
principal source of the soil and groundwater contamination and use of
institutional controls where necessary. However, cleanup levels for
the groundwater may not be achieved within 100 years for alternatives
that do not include deep soil treatment (Alternatives 1, 2, 3 and 4).
-------
-40-
Alternative
removes and
20 feet and
soils below
5 would provide the best overall protection because it
treats the principal threats between the land surface and
it provides deep in-situ soil treatment for contaminated
20 feet.
7.2
ComDliance with ARARs
Ali of the alternatives would comply with all Federal or State ARARs
or justify a waiver. Chemical specific ARARs would be met through
compliance with the groundwater protection standards (ie., MCLs) at
the Point of Compliance as defined in Ciba-Geigy's RCRA permit and
through compliance with the NPDES permit conditions for water removed
and treated in the waste management areas. The landvault utilized in
Alternatives 3, 4 and 5 would be designed in accordance with RCRA
regulations. Soils excavated in Alternatives 3, 4 and 5 would be
analyzed to determine if they are RCRA hazardous waste. If required,
RCRA hazardous waste would be treated to legislated treatment
standards pursuant to a treatability variance prior to land
disposal. Highly concentrated soils would be treated by a thermal
treatment process designed to comply with RCRA regulations for
hazardous waste thermal treatment. It is not anticipated Alternative
3 would achieve these standards for many of the contaminants of
concern due to the elevated levels present in the contaminated soil.
Alternatives 4 and 5 are designed to attain these standards pursuant
to the treatability variance.
Air emissions from the Site would be monitored to ensure compliance
with the Clean Air Act. Fenceline air monitoring will be conducted
to ensure that contaminant concentrations do not exceed levels
considered to be safe for human health. If levels are exceeded,
mitigative procedures such as dust suppression or vapor capture will
be employed to prevent harmful levels of air emissions from leaving
the Site. RCRA design standards will be incorporated into the
remedial design of all remedial activities.
Primary Balancing Criteria
7.3
Lona-Term Effectiveness and Permanence
Alternative 1 would not provide long-term effectiveness and
permanence with respect to the contaminated soils at the Site. Each
of the remaining alternatives would provide long-term effectiveness
through l~ting the migration of contamination or treatment of the
contaminated soils at the Site. Over time the effectiveness of
Alternative 2 may decrease as a result of cap/slurry wall failure
caused by improper construction (i.e., keying of the wall into an
unfractured impermeable clay layer) or inadequate operation and
maintenance procedures. However, as long as the cap and slurry wall
are properly maintained, the alternative could be effective. In
Alternative 3, the contaminants are bound to the soil by the
treatment process and the solidified material is contained on-site in
a RCRA landfill. The long-term effectiveness of
-------
-41-
Alternative 3 is uncertain since solidifying high level organic
contamination has not been demostrated to be effective in preventing
leaching of the waste into the groundwater. Alternatives 4 and 5
provide a greater level of long-term effectiveness than Alternatives
2 and 3 because thermal treatment has been demonstrated to
ezfectively destroy contaminants to the levels allowed by the
treatability variance. Alternative 5 provides the greatest long-term
effectiveness and permanence by the additional treatment of
contaminated soils below 20 feet.
7.4
Reduction of Toxicitv. Mobilitv or Volume Throuah Treatment
Alternative 1 would not reduce mobility, toxicity or volume at the
source of the contamination. Alternative 2 would isolate the
contamination from the environment, thus minimizing the forces which
drive contaminant mobility. However, toxicity and volume would not
be affected by Alternative 2. Each of the remaining alternatives
would reduce the mobility of the contaminants through treatment.
Treatability Studies would be conducted to demonstrate the level of
mobility reduction resulting in the stabilization/solidification
process proposed in Alternative 3. However, the volume of
contaminated material in Alternative 3 would increase due to the
stabilization process. Alternative 3 would provide minimal reduction
in toxicity. The toxicity of chemical contaminants at the Site would
be reduced by the thermal destruction process in Alternatives 4 and
5. Thermal treatment and destruction of -the organic chemical
contaminants at the Site through Alternatives 4 and 5 would virtually
eliminate all toxic effects of the excavated soils along with a
substantial reduction in volume. Alternative 5 provides the best
reduction of toxicity and mobility through treatment by utilizing
innovative in-situ treatments for contaminated soils below 20 feet.
7.5
Short-Term Effectiveness
Alternative 1 would not require construction or excavation that would
cause a health risk to workers. However, Alternative 1 would be the
least effective in achieving the overall groundwater cleanup levels
in the shortest time period. All of the remaining alternatives will
require varying amounts of time to implement. None will be
Lmmediately effective. No threshold toxicity criteria would be
exceeded by implementing Alternatives 2, 3, 4, and 5 and the health
risks to remedial workers is unlikely, particularly when appropriate
monitoring and engineering controls are applied. Of the alternatives
evaluated, Alternatives 3, 4 and 5 are more effective than
Alternative 2 because contaminated soil would be removed and
treated. Although Alternatives 3 and 4 require removal of
contaminated soils down to 20 feet, Alternative 5 would be most
effective in the short-term by isolating and treating the
contaminated soils below 20 feet. These soils are causing the most
Lmmediate threat because of their proximity to the groundwater.
-------
-42-
7.6
Imt:>lementabilitv .
.
The No Action alternative is currently operating. Technological
expertise, services, equipment and materials are adequately available
for the implementation of Alternative 2. The technical
impracticability waiver for the excavation of soils may be
granted if the Regional Administrator determines it necessary for
Alternatives 3, .4 and 5. Due to the uncertainty regarding the
effectiveness of stabilization/solidification of material
contaminated with elevated concentrations of organic contaminants a
treatability study would be conducted. A determination would be made
at the completion of the treatability studies, to be conducted during
the remedial design, regarding the effectiveness of
stabilization/solidification of material contaminated with elevated
concentrations of organic contaminants.
Thermal treatment capacity may be limited at the time of
implementation of Alternatives 4 and 5. New equipment may have to be
designed and constructed as a part of the overall schedule. However,
the technology base does exist for the completion of this
requirement. Ash from the thermal treatment process, any
solidified/stabilized material or any material from the
dechlorination process would be disposed of in a landvault after RCRA
legislated treatment standards, through a treatability variance
granted upon ROD signature, are met. In accordance with Superfund
LDR Guidance t6A, for herbicides, which are similar and applicable to
Site contaminants, the selected technology must demonstrate a 90-99.9
percent reduction for the contaminants of concern to be granted the
variance. All of the alternatives are technically and
administratively feasible. However, the results of the treatability
studies would determine the effectiveness of Alternative 3 on
elevated levels of organics.
7.7
Cost
Alternative 1 would not require any additional cost since no
treatment of the source is provided. The present worth cost of
installing a slurry wall and cap (Alternative 2) is estimated to be
$23,404,000. Alternatives 3, 4 and 5 are substantially higher in
cost due to increased efforts to permanently treat the contaminated
soil. The present worth cost associated with stabilization and
solidification of the contaminated soil (Alternative 3) is
$41,250,000. Thermal treatment and/or solidification/stabilization
of the con~aminants in the soil (Alternative 4) would cost
approximately $90,000,000 if solidification/stabilization of soils
with low levels of concentration is proven effective to $116,250,000
for complete incineration of all the contaminated material. The cost
for thermal treatment and/or solidification/stabilization of the
contaminants in the excavated soil combined with deep soil treatment
of contaminated areas below 20 feet, (Alternative 5), would range
from approximately $94,000,000 if solidification/stabilization of
soils with low levels of concentration is proven effective to
$120,250,000 for complete incineration of all the contaminated
-------
-43~
material. The treatability study would be conducted during the
remedial design to verify the level of contamination which could be
solidified/stabilized and still achieve RCRA land disposal standards
pursuant to a treatability variance. These costs include operation
and maintenance during the implementation of the alternative as well
as post remediation monitoring.
. ModifyLng Criteria
7.8
STATE ACCEPTANCE
The State of Alabama has concurred with the selection of Alternative
5 to remediate the contaminated soil at the Ciba-Geigy Site.
7.9
COMMUNITY ACCEPTANCE
Based on the favorable comments expressed at the August 1990 public
meeting and the lack of written comments received during the comment
periods, it appears that the McIntosh community generally agrees with
the selected remedy.
8.0
SUMMARY OF SELECTED REMEDY
In summary, Alternative 5 will achieve substantial risk reduction
through treatment of the principal threat at the Ciba-Geigy Superfund
Site. LDR treatment standards will be achieved, pursuant to a
treatability variance, granted upon ROD signature, prior to placing
the treated excavated material in the on-site landvault. As shown in
Figure 4, the treatment technology which has been demonstrated to
achieve these standards for the RCRA wastes present at the Site is
thermal treatment. Thermal treatment in this alternative may also
include a pre-treatment phase prior to the main thermal treatment
process. Three potential pre-treatment options include: solvent
extraction, followed by liquid injection incineration~ low
temperature thermal, followed by treatment of the desorbed volatile
organics/air mixture~ and critical fluid injection, followed by
liquid injection incineration. These options for pre-treatment will
be evaluated during treatability studies to be conducted during the
remedial design to determine if the main thermal treatment process
and/or cost effectiveness can be enhanced while still meeting levels
pursuant to the treatability variance. If any of the technologies
are proven to enhance cost effectiveness or the main thermal process,
it will-be u8ed.
Under certain circumstances, the pre-treatment option could totally
replace the main thermal treatment process. If any of the
pre-treatment technologies are proven to be more effective in
reducing the contaminant concentrations in the soil and is more cost
effective, it will be used instead of the main thermal treatment
process. Pre-treatment technologies that are not found to be
effective in reducing contaminated soil concentrations to levels
pursuant to the treatability variance or do not enhance cost
effectiveness will not be utilized.
-------
START
PJCCAVA1PD
SOIL.
DBBRJS
NOJf.HUAaDOUS
DBBRJS
RI!MOVAL
ANAL nil TO
DI!11!aMINB IP DllllIIS
II HAZARDOUS 011
NOII.HAZAaDOUS
IIIIIDf1' AMlHA 111)
..0PIIIl Y DllPOSI!D
AlllWI IBCYOJ!D
Figure 4
TREATMENT OF CONTAMINATED SOILS
PROCESS FLOW CHART
BASED 011 assULTS
OOIlTAMlllATI!D PlOMTI!CHIIOLOOIBS
SOlI. . SLUOOB
BVALUATI!D DUIJIIO
TUlATABIIJTY
STUDIIIS
HAZAIDOUS
TUIA TI!D
AS
HAZAIDOUS SOILS
o SOLYBHT IIXTIACT10N
o LOW 1I!MftIaATUU 11II!aMAL
AIIALYSISTO
I!NSUU THAT
wa.lVAAlANaI
AIR AOIIVII)
THI!IMAL
TUlATNBNT
ASH
o CU11CAL PLUID DIJBCl10N
.
.
.
.
.
.
.
4
10011
CDNalNTlAT10NS
.
.
.
.
.
.
.
.
.
.
.
s:::
~:
~ !
~:
.
.
.
.
.
.
.
4
LOW
CDNaINTIA ttONS
o SOUDIJIICA now
nABIUZAT10N
nBATI!D
AIIALYIII10
IINIUU THAT
~AllANail
AU AOIIIIYID
MA1UL\L
o DIDILOAINA nOlI
A80VII OIOUIID
leu
LAND VAULT
-------
-45-
Treatability studies will be conducted to determine the effectiveness
of solidification/stabilization of soils with low levels of
contamination. Stabilization/solidification will be utilized for
soils where it is proven effective by these treatability studies in
reducing the contaminated soil concentrations to LDR treatability
variance levels. However, a new innovative chemical treatment
technology, dechlorination may be tested during design and, if found
effective, may be used instead of solidification/stabilization for
some low level soils. Dechlorination uses a base (i.e., sodium
hydroxide) and an organic source of hydrogen and a catalyst to
accomplish reductive dehalogenation of halogenated materials. If
dechlorination is proven to be more effective in reducing the
contaminant concentrations in the soil and is more cost effective, it
will be used instead of the solidification/stabilization process. If
dechlorination is proven ineffective in reducing contaminated soil
concentrations to levels pursuant to the treatability variance and/or
does not enhance cost effectiveness it will not be utilized.
The contaminated soil may require pre-treatment to remove debris
(i.e., drums, scrap metal, construction rubble etc.) present before
the thermal treatment process. At the time of excavation during the
remedial activities, the debris may be removed from material that is
required to be treated. If drums are encountered, the contents will
be removed from the drums and it will be tested to determine if it is
hazardous waste. A determination will be made based on a method to
be detailed in the remedial design phase of the project as to the
hazardous or non-hazardous nature of the debris. If the debris is
determined to be of a non-hazardous nature, it may be decontaminated
and separated into a category of materials that can be disposed of
off-site and/or recycled. Debris that is determined to be of a
hazardous nature will be treated in an appropriate manner to be
determined at the time of excavation. The soils with low levels of
contamination will undergo stabilization/solidification. The soils
with high levels of contamination will be thermally treated. The
soils to be thermally treated would be blended in a tank which meets
the definition of a tank in Section 260.10 of the Code of Federal
Regulations (40 CFR). The purpose of the blending is to achieve a
homogeneous mixture prior to thermal treatment to. ensure proper
thermal treatment operations and to comply with operating conditions
determined in the trial burn. Ash from the thermal treatment
process, any solidified/stabilized material or any material from the
dechlorination process will be disposed of in a landvault after RCRA
LOR treatment standards, pursuant to a treatability variance granted
upon ROD signature, are met. In accordance with Superfund LDR
Guidance t6A, for herbicides, which are similar and applicable to
Site contaminants, a treatability variance requires that the selected
technology must demonstrate a 90-99.9 percent reduction in the
contaminants of concern.
In order to provide a constant treatment criterion throughout the
remediation process which will ensure compliance with the
treatability variance, the concentration of each contaminant of
concern in the soil after treatment must be no greater than 10% of
the corresponding cleanup level. Adherence to this criterion will
ensure a minimum of 90% reduction as required by the treatability
variance. Requiring that treated soils contain a concentration less
-------
1-
-46-
than or equal to a 90% reduction of the cleanup levels has been
pursuant to assuming that the cleanup levels are the lowest
concentrations of soils that will be excavated. Ensuring that the
cleanup levels are reduced by 90% (leaving a maximum of 10%) complies
with the lower limit of the percentage reduction allowed by Superfund
LDR Guidance 6A. In addition to providing a constant treatment
level, the soil before treatment will not have to be analyzed other
than for process control.
In some cases (i.e., if Gamma-BHC is found at 1000 mg/kg before
treatment, requiring that it be reduced to 0.1 mg/kg, see Table 8-1,
this will be a 99.99% reduction) the treatability variance standards
may be more stringent than the upper limit in Superfund LDR Guidance
t6A (99.9%), however it will remain less stringent than the LDR
standards for the contaminants of concern (i.e., BHCs = .066 mg/kg
DDTs = .087 mg/kg). In these cases, the treatability variance will
still be applied.
Table 8-1 provides the treatability variance treatment levels for the
contaminants of concern that must be achieved prior to placement of
treated soils into the RCRA landvault.
Confirmatory samples will be conducted during the remedial design to
ensure that contamination is not present above levels pursuant to the
ROD for surface and subsurface soils.' If confirmatory samples
indicate that concentrations of subsurface soils are above surface
cleanup levels, institutional controls, including deed restrictions
and/or other measures necessary will be utilized to ensure that any
future excavations of the contaminated soil will include the same
handling and treatment as set out in the selected remedy.
Following excavation activities, the area will be backfilled and
revegetated. As presented in Figure 5 (flow chart), if cleanup
l~vels are not achieved before a depth of 20 feet is reached,
extraction wells combined with isolation walls extending from the
land surface to the top of the Miocene clay and insitu soil flushing
will be utilized to flush contaminants from deep unsaturated soils,
thus decreasing the time required to operate the pump and treat
system implemented in operable unit one. The contaminated
groundwater extracted by these wells will be treated by the currently
operating waste'water treatment system. Innovative technologies
(insitu vacuum extraction or insitu bioremediation) may also be used
in concert with the soil flushing approach, if during design they are
found to be effective in reducing soil concentrations to cleanup
levels. Institutional controls, such as deed restrictions, will be
established t~~preclude usage of groundwater and minimize land use
until cleanup levels are achieved.
The results of the treatability studies for all technologies tested
during the remedial design will be evaluated and the technologies to
be used for remediation of the contaminated soils would be determined
and noted in the 30% Remedial Design Report. EPA will then issue a
public notice in a local newspaper and send a fact sheet to persons
on the mailing list to inform the public of the technologies proven
effective and which are to be implemented.
-------
-47-
TABLE 8-1
TRBATJmNT STANDARD POR SOILS AT TIlE CIBA-GEIGY SITE
The following table provides the maximum concentration
allowed in the residuals after treatment for the contaminants of
concern.
Contaminant
Maximum Concentration
Allowed After Treatment (mg/kg)
DDT
DDD
DDE
Alpha-SHC
Seta-SHC
Delta-SHC
Gamma-SHC
Chlorobenzilate
Diazinon
503
675
1,653
0.4
1.7
0.3
0.1
20.9
1.0
-------
Figure 5
DEEP SOIL REMEDIATION
ARE SUBSURFACE aJ!AN1JP UM!LS
AamM!D Ba'OIt!! 20 81
YES
NO
NO I&!P SOIL
RBS1JL1S PROM t1U!ATABILrIY
RmIEDIA'1Df R8QUIIIED
S'n1DIBS ON
o 1N...vnI VACUUMEX'11tAC'TION
o 1N...vnI BIORaa!DlA'I1<»l
191L\'1Df WAU.S W/WmIDRA W AL
~ INSTAUJID AROUND 1HB
camNtJ1! DEEP SOIL
RmIEDIA'1Df InmL mE BASED
OIIOUND W ATSt aJ!AHt1P OOALS
AlII! ACHII!VI!D AT 1HB
wmlDRAWAL ~
camNtJ1! OItOUNDW ATSt
~1nmL
0VI!ItAU. GROUMDW ATSt
aJ!ANUP UM!LS ARB
ACHJ!M!l).
-------
-49-
Air emissions from the Site will be monitored to ensure compliance
with the Clean Air Act. Fenceline air monitoring will be conducted
to ensure that contaminant concentrations do not exceed levels
considered to be safe for human health. If levels are exceeded,
mitigative procedures such as dust suppression or vapor capture will
be employed to prevent harmful levels of air emissions from leaving
the Site.
. All treated wastes will be land disposed in accordance with the
substantive requirements of the Land Ban Requlations, pursuant to
Section 3004 of the Resource Conservation and Recovery Act of 1976
(RCRA), as amended by the Hazardous and Solid Waste Amendments of
1984 (HSWA). After excavation and treatment, treated wastes will be
land disposed when LDR treatment standards for any characteristic
waste, listed waste, or requlated hazardous constituent pursuant to a
treatability variance granted upon ROD siqnature are met. The
treatment standards are based on the performance of treatment
technologies determined by the Agency to represent Best Demonstrated
Available Technology (BDAT) as promulgated on June 1, 1990. Wastes
that, as treated, contain RCRA hazardous wastes or hazardous waste
constituents, at concentrations which do not exceed the treatment
standards, are not restricted from land disposal units.
The selected alternative for the Ciba-Geigy site is consistent with
the requirements of Section 121 of CERCLA and the National
Contingency Plan. The selected alternative will reduce the mobility,
toxicity, and volume of contaminated soil at the Site. In addition,
the selected alternative is protective of human health and the
environment, will attain all Federal and State applicable or relevant
and appropriate public health and environmental requirements through
a technical impracticability waiver limiting excavation depths to 20
feet and a LDR treatability variance, is cost-effective and utilizes
permanent solutions to the maximum extent practicable. The selected
alternative for Operable Unit No.2 is consistent with previous
remedial actions conducted at the Site.
Based on the information available at this time, the selected
alternative represents the best balance among the criteria used to
evaluate remedies. Alternative 5 is believed to be protective of
human health and the environment, will attain ARARs (through
application of the treatability variance), would be cost effective,
and would utilize permanent solutions and alternative treatment
technologie. or resource recovery technologies to the maximum extent
practicable.
9.0
STATUTORY DETERMINATION
Under its legal authorities, EPA's primary responsibility at
Superfund sites is to undertake remedial actions that achieve
adequate protection of human health and the environment. In
addition, Section 121 of CERCLA establishes several other statutory
-------
-50-
requirements and preferences. These specify that, when complete, the
selected remedial action for this site must comply with applicable or
relevant and appropriate environmental standards established under
Federal and State environmental laws unless a statutory waiver is
justified. The selected remedy also must be cost-effective and
utilize per.manent solutions and alternative treatment technologies or
resource recovery technologies to the maximum extent practicable.
Finally, the statute includes a preference for remedies that employ
treatment that permanently and significantly reduce the volume,
toxicity, or mobility of hazardous wastes as their principal
element. The following sections discuss how the selected remedy
meets these statutory requirements.
9.1
PROTECTIVE OF HUMAN HEALTH AND THE ENVIRONMENT
The selected remedy protects human health and the environment through
treating a principal threat remaining at the Site, the contaminated
soils at ten of eleven former waste management areas addressed in
this ROD. The selected remedy provides protection of human health
and the environment by eliminating, reducing, or controlling risk
through treatment, engineering controls and/or institutional
controls.
9.2
ATTAINMENT OF THE APPLICABLE OR RELEVANT AND APPROPRIATE
REOUIREMENTS (ARARs \
Remedial actions performed under CERCLA must comply with all
applicable or relevant and appropriate requirements (ARARs). All
alternatives considered for the Ciba-Geiqy Site were evaluated on the
basis of the degree to which they complied with these requirements.
The selected remedy was found to meet or exceed the following ARARs,
as discussed below.
Clean Water Act
Perched water at certain areas and stormwater which contacts Site
materials during remediation activities will be routed through the
existing on-site wastewater treatment plant. In addition,
contaminated groundwater extracted by the deep soil treatment
technologies and the current pump and treat system, leachate from the
landvault and incinerator scrubber water will be treated before
discharge into the Tombigbee River through the current NPDES permit.
All current discharge limitations.will remain in effect for the total
facility discharge. This includes chemical-specific effluent
limitations based in the Organic Chemicals, Plastics, and Synthetic
Fibers (OCPSF) Guidelines, as well as the biomonitoring requirements
to evaluate compliance with toxicity requirements.
-------
-51-
Resource Conservation and Recoverv Act
Many RCRA requirements are considered relevant and appropriate for
remedial activities proposed at the McIntosh plant. The excavated
soils and sludges will be representatively analyzed to determine if
they are RCRA hazardous wastes. If RCRA hazardous waste is found it
will be disposed of in a landvault after RCRA legislated treatment
standards pursuant to a treatability variance, granted upon ROD
signature, are met. EP Toxicity and TCLP analyses will be performed
to ensure that treatment standards, through a treatability variance,
are met. A pilot study and a trial burn will be required to ensure
that the incinerator will meet the Destruction Removal Efficiencies
for the contaminants at the Site. The primary activities include
construction of isolation walls, construction of one or more new
landvaults, stabilization/solidification, incineration, groundwater
pump and treat, and possibly other innovative technologies. RCRA
design standards will be incorporated into the remedial design of all
construction activities so that the substantive requirements of all
applicable RCRA regulations are met.
Other Guidance To Be Considered
Other Guidance To Be Considered (TBCs) include health based
advisories and guidance. TBCs have been utilized in estimating
incremental cancer risk numbers for remedial activities at the
sites. The risk numbers are evaluated relative4to the no~lly
accepted point of departure risk range of 1x10- to 1x10- .
Clean Air Act
Air emissions from the remedial activities at the Site, including
thermal treatment, would be monitored to ensure compliance with the
substantive requirements of the Clean Air Act. Fenceline air
monitoring will be conducted to ensure that contaminant
concentrations do not exceed levels considered to be safe for human
health. If levels are exceeded, mitigative procedures such as dust
suppression or vapor capture will be employed to prevent harmful
levels of air emissions from leaving the Site.
Chemical-Soecific ARARs
Maximum Contaminant Levels (MCLs) and non-zero MCLGs are the
Groundwater Protection Standards set out in the Corrective Action
Program required by the 1985 RCRA Part B Permit. Those Standards
have been incorporated into the CERCLA ROD (September, 1989) for the
First Operable Unit, addressing the alluvial aquifer, and are
indicated in Table 5-8.
-------
-52-
Waivers
Section 121 (d)(4)(C) of CERCLA provides that an ARAR may be waived
when compliance with an ARAR is technically impracticable from an
engin~ering perspective. The waiver is granted for the selected
alternative should engineering methods necessary to excavate the
contaminated soil to the cleanup levels be technically
impracticable. EPA has concluded that it is technically
impracticable and less cost effective in this case to excavate to
depths in excess of 20 feet. This is based on the determination that
excavating beneath depths of 20 feet would pose a potential for
cave-in of the excavated area. Therefore, the cost of excavation due
to the implementation of measures to minimize this hazard would be
extremely high compared to standard excavation cost.
The selected alternative will comply with the LDRs through a
treatability variance for the contaminated soil and debris.
9.3
COST EFFECTIVENESS
The estimated cost of EPA's selected remedy is between $94,000,000
and $124,250,000. This range is depends on the amount of material
that can be treated by stabilization/solidification with the higher
cost assuming that all material will be thermally treated. Cost
effectiveness is determined by comparing the .cost of all alternatives
being considered with their overall effectiveness to determine
whether the costs are proportional to the effectiveness achieved.
EPA evaluates the incremental cost of each alternative as compared to
the increased effectiveness of the remedy. The selected remedy,
Alternative 5, although most costly, was chosen for its high degree
of effectiveness at reducing the mobility, toxicity, and volume of
the contaminants and its long-term protectiveness. EPA has
determined that the cost of the selected remedy are proportional to
the overall effectiveness; therefore, the remedy is considered cost
effective.
9.4
UTILIZATION OF PERMANENT SOLUTIONS TO THE MAXIMUM
EXTENT PRACTICABLE
EPA believes the selected remedy is the most appropriate cleanup
solution for the Clba-Geigy Site and provides the best balance among
the evaluation criteria for the remedial alternatives evaluated.
This remedy provides effective protection in both the short-term and
long-term to potential human and environmental receptors, is
implementable, and is cost-effective.
Thermal treatment, of the highly contaminated soils with
pre-treatment options proven effective during the design and
stabilization/solidification or dechlorination of low level
contaminated soil, if proven effective during the design, with
landvault disposal of the residuals will effectively reduce and/or
-------
-53-
eliminate the mobility of hazardous waste and hazardous substances to
the environment. Isolation from the groundwater combined with
in-situ treatment of any contaminated soils below 20 feet will
effectively reduce and/or el~inate the mobility of hazardous waste
and hazardous substances to the environment.
. 9.5
PREFERENCE FOR TREATMENT AS A PRINCIPAL ELEMENT
The statutory preference for treatment will be met because the
selected remedy treats the highly contaminated and most mobile
contaminated soils, a principal threat posed by the site, and
isolates and treats the lower contaminated soils.
10.0
DOCUMENTATION OF SIGNIFICANT CHANGES
The Proposed Plan released for public comment on July 30, 1990,
identified nine possible alternatives for remediation of contaminated
soils at the eleven former waste management areas at the Site. The
Proposed Plan also identified a combination of technologies
including I removal, on-site thermal treatment; stabilization and
solidification; and/or containment (landvault) as the preferred
alternative for remediation of the eleven contaminated soil areas at
the Ciba-Geigy Site. After reviewing comments received during the
initial comment period, the concepts in the nine alternatives were
reduced to four alternatives based on the similarities in their
technologies. These four alternatives were presented in the February
1991 Amended Proposed Plan.
After reviewing the comments received during the comment period for
the Amended Proposed Plan, an additional alternative which relies on
thermal destruction as the primary remedy but allows the flexibility
to conduct treatability studies for four innovative ex-situ treatment
technologies (solvent extraction, low temperature thermal, critical
fluid injection and dechlorination) during the remedial design has
been included. These changes were published in the July 1991
Modification to the Amended Proposed Plan. In addition, Alternative
5 included in-situ treatment in areas where the cleanup levels would
not be achieved at 20 feet. Soil flushing combined with isolation
walls and extraction wells. would be the primary means of treatment.
However, innovative technologies (in-situ vacuum extraction and
in-situ bioremediation) would also be used if during design they are
found to be effective in reducing soil concentrations.
EPA also decided to defer its decision on Area 8 (Fig. 1), which has
large boulders and scrap metals mixed with the contaminated soils.
The chemicals of concern in Area 8 include a variety of volatile
organic compounds at high concentrations (i.e., toluene, xylene)
which are not present in other areas. Area 8 is partially located
within a bluffline constructed under the supervision of the United
States Corps of Engineers and it is adjacent to the floodplain which
is currently undergoing RIIFS activities. This area will be
addressed in a future operable unit.
-------
-54-
Clean-up levels for soils were not clearly presented in the initial
proposed plan. In the February 1991 Amended Proposed Plan, EPA
presented soil excavation levels for the contaminants of concern
which would minimize the impact contaminants leaching from the soil
would have on the groundwater. The risk based excavation levels as
developed for the protection of groundwater were calculated to be 80
ppm total pesticides and 20 ppm total BHC isomers. Based on these
levels, it was estimated that an additional 114,880 cubic yards of
contaminated soil would be excavated and treated. Based on comments
received during the comment period, the total revised estimated
volume of contaminated material was 202,000 cubic yards. After
reviewing the comments received during the comment period for the
February 1991 Amended Proposed Plan, the modeling used by EPA to
determine soil cleanup levels have been modified.
The July 1991 Modification to the Amended Proposed Plan includes two
sets of cleanup levels, one for the surface soils and one for the
subsurface soils. The health-based subsurface soil cleanup levels
were calculated using either the Pestan or Summers models utilizing
site specific soil-water partitioning coefficients. The Pestan and
Summers Models were used to estimate groundwater contaminant
concentrations which result from migration of contaminants through
the soil column. The Pestan model was used in areas where an
uncontaminated zone exists between the contaminated soil and the
groundwater surface (Areas 2, 3, 5, 6, 7, 10 and 11). The Summers
model was used in areas where contamination has extended to or near
the groundwater (Areas 1, 4 and 9). The modified surface soil
cleanup levels, which will apply to the top twelve (12) inches
throughout the Areas Of Contamination, have been developed based on a
direct contact pathway for a future worker exposure scenario and
assume a commercial/industrial land use. No excavation would be
required in areas where the concentrations of the contaminants of
concern are below the cleanup levels. The cleanup levels were
adopted in the final selected remedy.
In the February 1991 Amended Proposed Plan, EPA had required site
excavation until the depth where "technical impracticability"
prevented further excavation. EPA previously defined "technical
impracticability" for soil excavation as when groundwater was
encountered. Following a review of comments received during the
comment period, EPA has limited the practicability of excavation to
depths les8 than 20 feet. Excavating beneath depths of 20 feet would
pose a potential for cave-in of the excavated area. In addition, the
cost of excavation due to the implementation of measures to minimize
this hazard could be extremely high compared to standard excavation
cost.
RCRA caps and slurry walls were also a part of the initial
alternative. If cleanup levels are reached, slurry walls or RCRA
caps will not be required to minimize the impact to the groundwater.
The selected alternative requires an isolation wall in concert with
localized groundwater extraction and treatment system and insitu
technologies to be evaluated during the remedial design, in the event
that cleanup levels are not achieved before an excavation depth of 20
feet is reached.
-------
-55-
The Scope of the individual Operable Units has also been refined and
a fourth Operable Unit, was added as follows.
OU .1
Contamination of the shallow (Alluvial) groundwater
aquifer.
OU '2
Contamination of soils at ten of eleven former waste
management areas.
OU .3
Contamination within the floodplain, the lower portion
of the dilute ditch and areas in the Tombigbee River
within close proximity to the Site.
OU .4
Contamination of soils in former waste management area
8 and the upper portion of the dilute ditch.
-------
--ADEM sO\l1.~,~
ALaA'MA 'q\
DEPARTMENT OF ENVI~M&tftl\. MANAGEMENT
. 1
sePtembe~'~~~\~'~H-
.
Leigh Pegues, Director
1751 Congo W.l.
Dickinson Drive
Montgomery. Al
36130
2051271.7700
Field Offices:
Unit 806. Building 8
225 O.moor Circle
Birmingh.m, Al
35209
205,. 942-6168
P.O. Bo. 953
Dec.tur. Al
35602
205/353.1713
2204 Perimeter Road
Mobile, Al
36615
205.. 479.2336
Mr. Charles L. Ktng, Jr.
Remedtal Project Manager
South Superfund Remed1al Branch
US EPA, Regton IV
345 Courtland Street, N. E.
Atlanta, GA 30365
Re:
Record of Dectston for the C1ba-Getgy Superfund Stte.
Dear Mr. Ktng:
Operable untt #2 wtll remove contamtnation of so11s at
ten of eleven former waste management areas. Alternative
number 5 has been selected as the remedy for the 10 sites.
The major components of the se 1 ected remedy for operab 1 e
unit two tnclude:
Excavatton of contamtnated so11s and sludges untt 1
estab11shed cleanup levels are reached or unttl
excavat10n becomes technically 1mpracttcable (1 .e.,
depths 1n excess of 20 feet>, whtchever is reached f1rst;
On-stte thermal treatment of approximately 65,000 cub1c
yards of highly contam1nated soils and sludge;
Stabtlization/so11dtf1cation or the utilization of an
tnnovative technology proven effective' during the
remedtal design, of approximate1y 62,300 cubic yards of
moderately contam1nated soils and sludge;
Dtsposal of treated s011 and res1dual ash from the
thermal treatment process in an on-site RCRA Minimum
Technology Class C landvault(s>;
In-situ so11 flushing comb1ned with 1s01ation walls and
injection wells to remediate areas where the risk based
cleanup levels are not achieved before an excavat10n
depth of 20 feet ts reached. Innovattve technolog1es
(in-situ vacuum extraction or in-situ bioremed1ation) may
also be used tn addit10n to or tnstead of 1n-sttu sol1
flushtng, tf during the remedtal destgn etther technology
15 found to be effecttve tn reductng contamtnant
-
Guy Hunt
Governor
-------
Mr. Charles L. K1ng, Jr.
September 18, 1991
Page 2
concentrat10ns 1n the s011 and 1s cost effect1ve. If the
technology 15 proven to be more effect1ve than 1n-s1tu
s011 flush1ng 1n reduc1ng the concentrat10ns of the
contam1nants 1n the s011 and more cost effective, 1t w111
be used instead of 1n-s1tu s011 f1ush1ng. If the
technology 15 not as effective as in-situ soil flushing
1n reduc1ng the concentrat10n of the contam1nants in the
s011 1t w111 not be utilized;
Backf11l1ng the excavated areas w1th common f1ll and
vegetat1ng the area and the establishment of a suitable
vegetat1ve cover;
Operat10n and ma1ntenance of landvault(s) for a m1n1mum
of th1rty years; and
Institut10na 1 controls for land use and groundwater use
restr1ct10ns.
We concur that alternat1ve number 5 1s protect1ve of
human health and the env1ronment.
JED/dws
;;;:;a'~ ~
/ Joseph E. Downey :/
/ Spec1al Projects
J
-------
,..to S1'.,.
~.,.. ~J'
.. II ..
~ I. I i
~-~
\ i
~~(~c..
UNITED STATES ENVIRcSQ\!1};.\, ~N)TECTION AGENCY
wA~~cm>RrD\T -26460
~!~ t!9 r\\ ''1\
. .
~~...
:\BR~\\C~
Q5=FIC!: OF
SOLID v.;.o.STE .o.r..D E\,'EFlGE'-C'" FlESPONSE
SEP 2 0 1991
MEMORANDUM
SUBJECT :
Consultation on the Remedy for the Ciba Geigy, Alabama,
Operable Unit 2 Record of Decision
FROM:
Timothy D. Mott, Chief-~ ~\.~~/~
Compliance Branch, OWPE -~ .
Doug Mundrick, Chief
South Superfund Remedial Branch, Region IV
Since the cost of the preferred alternative for this site is
over $60 million, on January 15, 1991, a consultation call was
conducted with Region IV and the AA OSWER to discuss the preferred
remedy. During this call HQs had requested that Region IV contact
us prior to signing this ROD. Since the Region recently indicated
that the ROD for operable unit 2 would be ready for signature
shortly, a call was conducted on August 30, 1991 to discuss the
preferred remedy.
TO:
Subsequent to our telephone conversation, OWPE discussed the
preferred alternative with the AA's office. On September 10, 1991,
the Special Assistant to the AA contacted OWPE to inform that the
AA has concurred with the preferred alternative (alternative 5).
This alternative has been determined to be protective of human
health and the environment, attains applicable ARARs and is cost
effective. This memorandum confirms and closes out the required
consultation process. If there are any questions, please contact
Neilima Senjalia at FTS 398-8630.
cc:
B. Hanson, OSWER
B. Diamond, OWPE
S. Mansbach, OWPE
J. Smith, OERR
A. Collins, Region IV
C. King, Region IV
P. Mancusi-Ungaro, Region IV ORC
E. Akin, Region IV
I'rWMl CII ~ P..,
------- |