United States
Environmental Protection
Agency
Office of
Emergency and
Remedial Response
EPA/ROD/R07-88/013
September 1986
SEPA
Superfund
Record of Decision
Syntex Verona, MO
-------
50272. 101
REPORT DOCUMENTATION
PAGE
1. REPORT NO.
EPA/ROD/R07-88/013
4. Title and Subtitle
SUPERFUND RECORD OF DECISION
Syntex Verona, MO
~irst Remedial Action - Final
Author(s)
9. Performing O..anization Name and Add,ess
12. Sponsoring Or.anization Name and Address
U.S. Environmental Protection
401 M street, S.W.
Washington, D.C. 2046U
15. Supplementary Notes
Agency
.' "
2.
3. Recipient's Accession No.
5. Report Date
05/05/88
6.
8. Performing Organization Repl. No.
10. Proiec:t/Task/Work Unit No.
.- -- ._---
11. Contracl(C) or Grant(G) No.
(C)
(G)
--" -------------.
13. Type 0' Report & Period Covered
800/000
14.
16. Abst. .. \Limit: 200 words)
The Syntex Verona (SV) site, formerly operated as Hoffman-Taff, Inc., was purchased
in 1969 by Syntex Agribusiness. The site is located 30 miles southwest of Springfield
in extreme southwestern Missouri. Approximately 500 people live in Verona, Missour{,
which borders on the site. The site area encompasses approximately 180 acres along the
east bank of the Spring River. The majority of the active portion , of the facility is
located within the spring River lOO-year flood plain. SV was used to manufacture
exachlorophene from 1970 to 1971, which produced the byproduct.
_,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), referred to as dioxin. From 1971 to 1988
EPA and Syntex Verona conducted numerous site investigations. The findings showed
contamination both on~ and offsite which may be related to the former activities at the
site. The major areas identified as being contaminated are the Slough Area, Lagoon
Area, Spill Area/Irrigation Area, Burn Area, and ~rench Area. Dioxin contamination
ranged from 1 ug/kg to 1,380 ug/kg, with the maximum concentrations occurring in the
Lagoon Area. In addition to dioxin contamination, other organic and inorganic compounds
were identified. The concentrations of these compounds were below the level of concern
for human health. The primary contaminant of concern affecting the soil .is dioxin. r
(See Attached Sheet)
11. Oocument Analysis a. Oescriptors
Record of Decision
Syntex Verona, MO
.First Remedial Action - Final
Contaminated Media: soil
Key Contaminants' dioxin
b. Identlffeni/Open.Ended Terms
c. COSATI Field/Group
. ",vailability Statemerit
(See ANSI-Z39.18)
See 'nstructions 0" Reverse
19. Security Class (This Report)
None
21. No. 01 Pages
48
----
20. Security Class (This Page)
None
22. Price
OPTIONAL FORM 272 (4-77)
(Formerty NTI5-35)
Department 01 Commerce
-------
DO NOT PRINT THESE INSTRUCTIONS AS A PAGE IN A REPORT
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16. Abstract. Include a brief (200 words or less) factual summary of the most significant information contained in the report. If the
~eport contains a significant bibliography or literature survey, mention it here.
17. Document Analysis. (a). Descriptors. Select from the Thesaurus of Engineering and Scientific Terms the proper authorized terms
that identify the major concept of the research and are sufficiently specific and precise to be used as index entries for cataloging.
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p.nded terms written in descriptor form for those subjects for which no descriptor exists.
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... : :?93 :. - 381-525 (9393)
OPTIONAL FORM 272 BACK (J
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1DA/ROD/R07-88/013
'ntex Verona, MO
r'irst Remedial Action - Final
16.
ABSTRACT (continued)
The selected remedial action for this site includes: excavation and offsite thermal
treatment of dioxin-contaminated soil exceeding 20 ug/kg and offsite disposal of the ash
residue; dismantling and decontamination of equipment with a series of solutions and
aqueous rinses; installation of a clay cap with a vegetation cover over the Trench Area;
and maintenance of vegetation cover over surface soil containing levels of dioxin from 1
ug/kg to 20 ug/kg. The estimated present worth cost for this remedial action is
$5,617,000.
-------
II (.,' U ,.. t: y ; eL' I ~nj
72'tf':j. C-j/t..j
6' 1/3() -
v{'N/1D
RECORD OF DECISION DECLARATION
SITE ~A~fE A~D LOCATION
o Syntex Agribusiness, Inc., Verona, Mjssouri
STA TE\fE'(T OF BASIS AND PURPOSE
This decision document, presents the selected remedial action for the Syntc:x
Agribusiness site in Verona, Mjssouri. This final plan has been developed in
accordance with CERCLA, as amended by SARA, and, to the extent practicable, the
Nation:ll Contingency Plan. This decision is based on the administrative record for
this site. The attached index identifies the items. which comprise the administrative.
record l.:;-;:.r. whi::: the sd:ction of the remedial action is based.
DESCRIPTIO~ OF THE SELECTED REMEDY
This remedial action represents the final action for dioxin~contaminated soils and
equipment at the Syntex Agribusiness site. This remedial action addresses the
prin::;:':lJ t!-.r;::lts at the sire b! excavation and thermal treatment of soils which exceed
the 20 ppb action level established for the protection of public health and the
environment at commercial facilities. Thermal treatment results in the destruction of
'dioxin, permanently removing the contamination from the environment. A vegetative
cover will be maintained over surface soils containing levels of dioxin from I to 20
p;:-t,
The major components of the selected remedial action include:
(\
EXC2\"3t:on of a!! dioxin-contaminated soils exceeding the 20 ppt
level.
ac!icr:
o
Dismantle, as appropriate, and clean contaminated equipment with a
series of solvent and aqueous rinses.
o
Thermal treatment of soils and cleaning solutions excavated and
removed from the sj!~. '
o
Maintain vegetative cover over surface soils containing greater than I
ppb dioxin.
o
Install a vegetative clay cap over the Trench Area and a gravel
drainage-interception trench upgradient of the Trench Area.
DECLA RATIO:"
The selected remedy is protective of human health and the environment, attains
Federal and State requirements that are applicable or relevant and appropriate to this
. ;~~~.:i~J 3ction :lnd is cost-effective. This remedy satisfies the statutory p!'efe;~::..:'~
for remedies that employ treatment that reduces toxicity, mobility or volume as a
principal element and utilizes permanent solutions and alternative treatment (or
.
-------
resource recovery) technologies to the maximum extent practicable. The remedy under
this operable unit only addresses dioxin-contaminated soils and equipment. A five
year review will be conducted at the Trench Area because contam~nation will remain
a bove the health-based criteria. This review will serve to assure effectiveness of the
remedy in the Trench Area. A second operable unit will be prepared if necessary to
address remediation of the gro\lndwa~er. Spring River and the Trench Area at the site.
5-S'~~
Date
~2.lV / ~ w;:r-
Regional 'Administrator
Region VII
.
-------
RECORD OF DECISION
FOR
FI~AL MANAGEMENT OF DIOXIN CONTAMINATED
SOIL AND EQUIPMENT AT
SYNTEX AGRIBUSINESS. INC.
VERONA. MISSOURI
Prepared by:
l' .S. E~VIRO~MENT AL PROTECTION AGENCY
April 29, 1988
.
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TABLE OF CONTENTS
1.0
INTRODUCTIOf\;
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
BACKGROUND
SITE HISTOR Y
PREVIOUS STUDIES
SUMMARY OF INVESTIGATIONS AT THE SYNTEX,
VERONA SITE
ENFORCEMENT HISTORY
"
,
,
,
PUBLIC PAR TICIP A TION
,
SU~1MAR YpF SITE RISKS
DOCUMENTA TION OF SIGNIFICANT CHANGES
,
,
AL TERNA TIVES E:Y ALUA TED
"
I
NO ACTION:
I
2.0
:.1
"" ..
... ..
.;;."
:.4
ST ABILIZA TIO~
REMOVAL
EQt:IPME~T REMEDIATION
3.0
SU~1MARY OF THE COMPARATIVE ANALYSIS OF THE
AL TERNA TIVES
3.1
PROTECTION OF HUMAN HEALTH AND THE ENVIRONMENT
CO\fPLIA!'CE WITH APPLICABLE OR RELEVANT Af\;D
APPROPRIATE REQUIREMENTS
3.3 . REDUCTION OF TOXICITY. MOBILITY OR VOLUME
.. .,
~.-
3.4
3.5
3.6
.. .,
,
3.8
3.9
.
SHOR T.. TERM EFFECTIVENESS
LO:\G.T~RM EFFECTIVENESS AND PERMANENCE
IMPLEMENT ABILITY
COST
COM?vtUNITY ACCEPTANCE
STATE ACCEPTA~CE
i
PAGE
2
4
8
9
12
12
13
13
15
15
16
17
18
21
21
...,
"--
22
....
-)
.....
.;.)
:5
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4.0
5.0
TABLE OF CONTENTS
(tootioued)
PAGE
THE SELECTED REMEDY
26
4.1
ACTION LEVELS
26
4.2
St:BSITE REMEDIAL ACTION
REMEDY SUMMAR Y
30
"'~
.1./
4.3
STATUTORY DETERMINATIONS
31
,
:1
LIST Of TABLES
TABLE NO.
PAGE
.
1.1
,
Summah of Max.imum Concentration of Non-Diox.in Contaminants
(198:, ')984 an;d 1985 Data) ,
I
5
I.:
Maximum Concentrations of Tentatively Identifi:d Compounds
in Groundwater (1985 arid 1986 Data)
6
1.3
Fish (Sucker Type) and Sediment Samples Taken from the
. Spring River
7
:.1
Summary of Remedial Alternatives
14
3.1
Estimated Cost of Proposed Remedial Alternatives
24
4.1
Select:d RemedS' for Syntex, Verona
28
LIST OF FIGURES
FIGURE NO.
PAGE
1.1
Site ~1ap - Dioxin Surface Contamination
3
ii
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1.0 INTRODUCTION
1.1
BACKGROUND
The facility. now owned by Syntex Agribusiness Inc. is located in extreme
southwestern Missouri in. the t9wn of Verona. Verona (population 500) is
approx.imately 3-0 miles southwest of 'Springfield, Missouri.
The Spring Ri\'er. which arises about three miles south of Verona, flows
northward along the western outskirts of Verona. The Syntex facility is located
west of Verona and occupies about 180 acres primarily along the east bank of the
Spring Ri\'er. The majority of the active portion of the facility is located within
the 100-year floodplain of the Spring River.
The facility was used to manufacture hexachlorophene from 1970 to 1971. The
manufacturing process resulted in the by-product production of 2.3,7.8-
tetrachlorodibenzo-p-dioxin (TCDD). often referred to simply as dioxin. Dioxin.
trichlorophenol (TCP). and hexachloropMne have been listed as hazardous wastes
under the Resource Conservation and Recovery Act (RCRA) and hazardous
substances under the Comprehensive Environmental Response, Compensa~ion and /
Liability Act (CERCLA). ---
The past operation of a leased production building at the Verona facility has
resulted in several areas of known or suspected dioxin contamination. The major
subsite areas of known or suspected contamination addressed in this plan are the:
Lagoon Area; Slough Area; Spill Area/Irrigation Area; Trench Area; and Burn
Area.
1.:
SITE HISTOR Y
Th~ en\ ironmentJI con.:erns at the Verona facility, began about 1960 when th~
facility was owned and operated by Hoffman-Taff. Inc. Hoffman-Taff produced
:A.5-trichlorophenoxy-acetic acid (2,4.5-T) for the U.S. Army as part of the
production of the defoliant commonly known as Agent Orange.
In 1969. Syntex Agribusiness, Inc., purchased the Verona facility from Hoffman-
Taff. !'orthe~st Pharmaceutical and Chemical Company (NEPACCO) had
pre\ iously entered into a lease agreement with Hoffman-Taff. which was
continued after the purchase by Syntex.
The production of :.4.5-T and hexachlorophene involves the intermediate
production of 2.4.5-trichlorophenol (TCP) and subsequently the potential
formation of dioxin, (2,3,7,S-tetrachlorodibenzo-p-dioxin or TCDD). However.
these "contaminants" were removed from the pharmaceutical grade
hexachlorophene. thus creating waste streams containing TCP and dioxin. The
produ.:tion of hexachlorophene was discontinued in 1972 when the FDA placed
restrictions on the use of hexachlorophene and the market collapsed.
1.3
PR EVIOl'S STUDIES
Numerous studies at the Verona facility date as far back as 1971. Several of the
studies involved off-site locations that were suspected of being related to the
facility.
.
-------
The following is a brief chronology of the various investigations related to the
Syntcx. Verona site.
1971
1978
1981
198:
1983
1984
1985
1986
1987
1988
Missouri Geological Survey and Water Rersourc'es conducted d) e
test to determine migratory paths leading from site. Missouri
Conservation Department sampled Spring River 1.5 miles
downstream of Syntex.
EPA collected water, sediment and fish samples at and 3 miles
downstream from Syntex.
Fish and sediment samples were taken Crom Spring River.
Fish and sediment samples were collected Crom Spring River.
Trench perimtter and boring soil samples were collected by
Syntex. Additional soil sampling was conducted in the burn,
irrig3tion and old lagoon subsite areas by Syntex under EP A
oversight.
Consent Order between EPA and Syntex, see Section 1.5.
Fish and sediment samples were collected from Spring River by
EPA and MDNR.
Consent Agreement between EPA and Syntex, see Section 1.5.
Fish and sediment samples were collected from Spring River by
EPA and ~1D~R. '
Syntex collected soil samples under EPA oversight. Groundwater
samples were collected from wells on the facility property, Fish
and sediment samples were collected from stations on the Spr,ing
River.
Groundwater samples were collected from wells on the facility
property. Fish and sediment samples taken from Spring River.
. Fish samples were collected from the Spring River.
Sediment samples were collected from the Spring R)ver.
1.4
SUMMARY OF INVESTIGATIONS AT THE SYNTEX, VERONA SITE
The numerous investigations at the Syntex, Verona site have Cound contamination
both on and off site which may be related to the former activities at the site,
The following text summarizes these findings.
1.4.1 SQil
The soil sampling efforts at the Syntex facility have identified several areas or
subsites significantly contaminated with dioxin. These subsites are delineated on
Figure I.\. Most of the contaminated areas or subsites are, or have beeI'
.
2
-------
.. .. '. .. ~ .. .. Ie .. .. . .. .. ...
. . . ~ .. .. . .. .. .. . 0 .. ..
o 8 8 l, 8 8 8 8 '. 8 0 8 'J
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o 0"- NO - U 5Z
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------'- ,
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Irrlgalion / SPill''':'.:.:..1 Lagoon' -~~_-:--=.:: u :-=.::::
Areaf;'r: Area ~
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.-------
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1\
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- - - - -. - - - - -- - - - - -
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-.-. - -.
"U
Hot U..,...ted
- -..
DIOXIN
CONTAMINA nON
SURFACE
C" ':':'J
C:=J
l~;':X;~J
E::~
-
C I 'Pb (
, - ~ P""'Ub ppb
!Ii ~ '" I'pb
2U
"UU ppb
... d Jlu ." ppb
Upper IImll o' I ufllll".I"I,.IoIII,
..,.. oct".. '0".... '''0-''
SYNT EX I\GRIBUSINt 5S
VERONI\ FACllIl)
lutJuVI.d ho'" t ", \.."
''It(''~II. I..W' I,
REV.Sf (, "Ov 1911'
!'"}t,
iigurc 1.1
-------
asso.:iated with specific plant activities. These subsite areas are labeled as the:
Slough Area; lagoon Area; Spill Area'irrigation Area; Burn Area; and Trench
Area.
In addition, several areas scattered across the plant site were investigated for
fugitive cor.tamination. The RGrid" Area is used as the general description for
the overall site grounds sampling' efforts. The dioxin contaminant levels in these
areas generally are less than I ppb, with the exception of one area directly ea$t
of the Lagoon Area which has 3 ppb dioxin.
. .
The highest concentrations of dioxin occur in the Lagoon Area, with dioxin
levels as high as 1380 ppb. Maximum dioxin concentrations in other subsite areas
are the Trench Area 67 ppb, the Burn Area 27 ppb, the Irrigation Area 29 ppb.
Spill Area 4.9 ppb and the Slough Area 5.3 ppb. The remainder of the sight
showed little or no dioxin contamination as revealed during the RGrid" Area
sampling effort.
Other organic and inorganic compounds, in addition to the dioxin contamination.
were identified on the Syntex, Verona site. These are summarized in Table 1.1.
As is discussed in Section 1.6 and 3.1 the Agency for Toxic Su bstances and
Disease Registry (A TSDR) has determined that the concentration of these
compounds is below the level of concern for human health.
1.4.: Groundwater
Groundwater samples collected at the Syntex facility have shown no dioxin in the
groundwater. However. several other' compounds have been identified in the.
£~(.i.,;nj\\ :It;;r. The maximum concentration cf the compounds det::.:t::j in t:-:::
groundwater are presented in Table 1.2 .
I.~,::- F!~r. :l~d S~djment
The fish and sediment sampling program required by the Consent Agreement and
Order signed by EPA and Syntex on September 6, 1983 and discussed in Section
1.5. has resulted in regular analyses of Spring River fish and sediment to
determine the level of dioxin contamination. Analyses indicated a maximum
level of 52 pp~ dioxin (TCDD) in whole fish in 1981 and a lower level of 17 ppt
dioxin (TCDD) in 1986, Analysis of fish fillets (edible portion) indicJte a
m:nimum le\'e/ of 40 ppt in 198: and 3 lower le\'el of 2.5 ppt in 1986. 0.3 miJes
downstream of the site. The Food and Drug Administration (FDA) advisory le\'el
for edible portions is 25 ppt for reduced consumption and 50 ppt for nCo
consumption. Spring River sediment samples revealed dioxin, concentrations of
12 ppt in 1981, 1.6 ppt in 1984 and 6.4 ppt in 1987, 0.3 miles downstream of the
site. All other sediment samples collected from the period 1981 through 1987 at
st3tions 0.3 miles. 6.0 miles and 12.0 miles downstream revealed nondetectar.1e .
Icvels of dioxin. Table 1.3 presents a summary of these analyses.
1.5
ENFORCEMENT HISTORY
A Cons.:r.: O:.:~~ \\:15 signed bc!\\ccn S:ntc.\ and EPA pursuant to S:::tic;. :::::-
of RCRA 4:, USC 6927 on August 6, 1982. The agreement provided for
"...monitoring. testing, analyses, and reporting regarding the disposal areas on the
Facility."
..
4
-------
TABLE 1.1
SYNTEX
S '..: r."\r"':!!" \ of "f3,imum Concentration of Non-Dioxin Contaminant5
198: 1984 and 1985 Data
All ConcentratioM in DDm
L.a loon Irrilation Trench Trench
C"'~-"r.\Jr.,:! Soil Soil Soil Water Other'
1.:.4.5-
telr 3;h lore; b: :ue n: .465 .238 .0796 .009i
1.:.4-
trl:h!crot-enHn: 46.40 3.670 .380
1.:.':'
trim:th yl benzene 43.20
l.:-di;hlorobenzer.: .590
1.3-dichlorobenzene M
1.4-d I: h iorobenzene 1.170 20.20 .290
]-chlcrod:::ir.: .330
:.4.5- '
trichlcrophenol ! 244.0 1.260 20.70 5.70 .058::A
:.J.~. :
tr icr.lcrophen~I " 134.0 .190 .120
:.4-dich loropheno: i .830 .190
:-me:h yl phenol 6.440
2-meth ylnaphthalene 3.750 1,400.0 47.0
4-methyl..henol 4.910 1.0
A::-::-- .n~~~ 3.:50
Acete;n: .550
Anthracene i 27.60
.,
Aroclor 1:3: I .240
,j
Aro:\or 1:4: ' 11.30
I
Aroclor 1:48 I 2.70
A roclor 1254 .297 .580
s:-::; .p
jiUCfJ:::h::1: ~t
Benze; (K)
fIuor3nthen: M
B:r.zc:: J:i.: ~1 11.10
Benzy j Ji:oho! .Oi5
Bis (2-ethylhexyl)
phth31a te I.' 30 5.410 .160
BUly i b::nyl
ph th3la te 1.60
Chlorobenzene .105 .0019
Chrysen: M
Di-n-butyl phtha13te M 1.40
D~..r.-,:.:~y~ ~r.:r.:1:3:: M
DI:::::'.:'~:' _rJ~. 1.110 1.60
E:;;:! !::r.::::.:: .OC6~ .033
FluN3nt!':ene M
F!.. :.r:r:~ 51.0 2.30
FI uorOtr IC hloromet h3 n: .0015 3.7408
He~achlorophene 1700 13.80 H90
Meth ylene chloride .790 .250 ~
Naphthalene .490 1.390 Sss.O 13.0
o-Xylene .039 200.0
Ph:nJ:::hr:n: !.SO .780 120.0 5.50
Ph:n:.! 3.670 1.800
Pyre::: M
Toluene 1.220 .30
Tridecane 32.0
, - GenerJI area outside of the smaller. individually
s3m"led areas (lagoon. irrig3 tion, and trench areas)
.
-\
B
M
Concentrations as high as 1,540 have been found at a depth of )-4.5 feet.
Coc:entr3tlons as high as 46.200 have been found at a depth of 3-4.5 feet.
Compounds identified bUI not quantified.
-------
\ TABLE. 1.2
Ma:ttimum Concentrations of Tentativeh'
Identified Comoounds in Groundwater
U2J2.ml
1985 and 1986 Da ta.
I. I. I-trichloroethane
I.I.:.:-tetrachloroethane
1.1-0\ ybisbenzene
1.:.3-tri meth y I benzene
: 1.2.4-tri meth y: benzene
';1.:-d ich lorocyclohexa ne
"!I.:-d imeth ylben z: ne
:1.3-d im::th ylt.enzene .
.1.3-di n i tra te-I.:.3-propa netr iol
:,.~.-dichlorobenzene
2.:-bi-l.3-dioxolane
;.:-dimethyl-l.3-propanediol
':.:-thio bisetha not
:~.5-din1ethyl tetrahydrofuran
,!:-meth~'1-3-( I-methylethyl) ,oxirane
,: 3.5.5-t~imeth yl-I-hexene
3-chlorophenol
J-('h 10ro~henol
4-fI uoro-I.I-biphen yl
5-methyl-l-hexene
5-meth yl-I-hex yne
6-n i trO-:'p icol i ne
. Benzeneacetic acid
Bromocyclohexane
Chlorobenzene
Dimethylbenzene
Ethylbenzene
Hexanedioic 'acid. dioctyl ester
Hexanoic acid
Methylbenzene
\fethylene chloride
Meth y Iguanidine
N-n-dimeth ylforamide
Pentanoic acid
Tetra h yd ro-2H -pyra n -2-met hanol
Trans-4-chlorocyclohex3nol .
Trichloroethane
.
6
.047
.320
.120
.023
.005
.047
.156
.111
.784
.058
.045
.036
:;:6
.012
.058
.001
.151
,110
.050
.047
.046
.148
.031
.00:
.048
.046
.041
.386
-..-
.J- .
.090
.047
.84:
.265
.061
.038
.Ol~
.004
-------
TAB'..E 1.3
FIS" (SUCKER TYPE) ANO SEDIMENT SAMPLES TAKEN FROM THE SPRING RIVER
SEDIMENT SAMPLES (ppt)
L:::cation
1981
1983
1984
1985
1986
1987
.. ..... .....
Loc Ite. , 12 NO (27) 1.6 NO (3.0) lID (7.5) 6."
0.3 Miles Downstream
Lee: I/o. 3 NO (1 0) ND(9) NO (1.5) NO (2.3) NO (2.6) ND (0.8)
6.0 Miles Cownstrea~
Loc No.5 NO (1.2) NO (2.5) NO (9.1) ND (0.8)
12 . 0 Mil es Downstrea"
FISH SAMPLES (ppt)
Sampl e Type
1981
1982
1983
1984
1985
1986
'9a7
........... ..
~::=~.:- ":. .
C.3 Mi,es Dc.~strea"
"';"::~ ~~s...
f; llet
~~ 28 26 " e.: 2' .3
"0 20 " 3.0 2.5 i..a
3; 22,3" " 16.9 '3.:'
" 3.0 t..t. 3.t.
12 6.0 6.2 7.0
3 NO 1.3 1.8
" 5.' 6.9 8.3
2 1 1.7 1.3
3 NO ;.a 1.7
NO NO 1.2 0.3
L::c~; ~"': ":.. ,
\O-.~~e fis"
fill et
3.G Miles Dc.~s:~eam
Location No. 3
6.0 Miles Downstream
Whole fish
fillet
Location No. t.
9.: ~:ies C~.~s:-ea-
Whole fish
fit let'
Location No.5
~,.o Mi~es ::.-~~~ea-
Whole fish
fillet
data not available
It:) None Detected
( ) Detectio~ Limit
The 198' and ';83 data was generated by the U.S. EPA.
The 1982 data was generated by Dr. Gross of the University of Nebraska'Lincoln
The 1984 and 1985 data was generated in compliance with the Fish and Sediment Plan
8"'IC t~e a:"la,ys~s "'e~e ~-t:);:::e: by i:,-. Ciross at the t.::"Iive~s:ty' of Nebraska'Lincoln.
The '1986 and 1987 data was generated in compliance with the Fish and Sediment
and the analyses were performed at Syntex Research Laboratory in Palo Alto, CA.
.
-------
A second Consent Agreement and Order between Syntex and EPA ""'35 signed
September 6. 1983 pursuant to Section 106 of- CERCLA. 4: USC 9607 and Se~tion
3013 of RCRA. The order required the following actions:
o posting of warning signs around specified disposal areas;
o development and submittal of a Sampling and Analysis Plan for defining
the ;xtent and nature o( dioxin contamination;
o implementation of Sampling and Analysis Plan upon approval by EPA;
o development and submittal of a Fish and Sediment Sampling Plan for the
dioxin contamination in the Spring River;
o implementation of a Fish .and Sediment Sampling Plan upon approval by
EPA;
o prepara tion and submittal of a Remedial Alternatives Report based on
the results of Sampling and Analysis Plan;
o preparation and submittal of an implementation plan which will include
plans and specifications for the preferred remedial alternative, schedule
for implementation and reporting, description of the necessary reports
and safety plans. .
This Conscnt and Agreement Order is currently being carried out by Syntex.
The site has b~en placed on the National Priority List of Hazardous Waste Sites.
In addition the site is included on the State of Missouri Registry of Abandoned
or Uncontrolled Hazardous Waste Disposal Sites pursuant to the Missouri
regulation found at 10 CSR 25-10.010.
1.6
PlTBLIC PARTICIPATION
Public p3rticipation in the process of sel::ting the final remedy at other
South\\C3i \1issouri dioxin sites beg:!.n in ~1.:!: 198~ when the EPA anneou:'..:::.:.
p!:!ns to set up an incinerator system at the Denney Farm site. Public hearings
were held by. the EP A and the Missouri Department of Natural Resources
\\1DSR) in September 198~ regarding the permit for the incinerator system. The
incinerator arrived at the Denney Farm on December 15, 1984 and' between
. February and April 1985 conducted four trial burns. These trial burns
successfully and safely removed and destroyed the dioxin contained in the
contaminated materials. On July 18, 1985 the incinerator began burning a
variety of dioxin-contaminated soils and liquids. Phase I operations were
completed on. September 19, 1987 with materials from Denney Farm, Erwin Farm.
Talley Farm, Rusha Farm and Neosho Wastewater Treatment School being
successfully treated. In March 198'7 the EPA and MDNR held a public meeting tCo
discuss extending the permit for incinerator operation iu Denney Farm. The new
permit allowed the EP A to operate the incinerator through May 1989 as part oC
Phase II. Proposed activities under Phase II include burning dioxin-contaminated
material from additional southwest Missouri sites, i.e. Baldwin Park in Aurora.
the Syntex, Springfield facility, and the Syntex, Verona facility.
Public participation in the selection of a final remedial action for the Syntc\
Agribusiness site in Verona, Missouri began with the public release of the Syntex
"Remedial Alternatives Report," the EPA "Proposed Plan for Final Management
of Dioxin Contaminated Soil and Equipment, Syntex, Verona" and Administrativc
Rc~ord on ~1:lrch:L 1988. The Syntex Report evaluated remedial altern3ti\~:
for tho dioxin-contaminated soil and equipment and presented general plans for
future monitoring of the local ground waters. The EPA Proposed Pia'
recommended excavation and treatment of dioxin-contaminated soils an
cquipment abo\c an 3~tion le\ cl of :0 ppb dioxin for surface soils an,:;
.
8
-------
maintenance of a vegetative cover over soils containing between I ppb and :0
ppb dioxin. Installation of a vegetated soil cap and gravel dr~ina8e.intcr.:eption
trench was proposed for the Trench Area.
A public comment period was held from March 21, 1988 through April ::, 1988
for the Syntex Remedial Alternatives Report and EPA Proposed Plan. A publi,;
meeting wa's held on March 29, 1988 'to discuss the Syntex Remedial Alternatives
Report and the EPA Proposed Plan.
All documents used in selection of the remedy ire included in the Administrative
Record. The Record of Decision and Responsiveness Summary will also be
included in the Administrative Record which is available for review at a local
repository in Verona, Missouri and the U.S. EPA Region VII office in Kansas
City, Kansas.
1.7
SCMMARY OF SITE RISKS
1.7.1 Contaminants of Concern
The primary contaminant of concern at the site is 2,3,7,8 TCDD, commonly
. referred to as dioxin. Dioxin is considered one of the most toxic compounds
known. with the LD-50 (lethal dose to 50 percent of tested populations) level for
male guinea pigs, the most sensitive species, being 0.6 ug/kg.
Although dioxin has been highly toxic in all species tested, there are large species
differences in sensitivity, with the LD-SO for ,hamsters being 1,157 to 5,05 I
ug kg The characteristic signs and symptoms of lethal dioxin poisoning are
severe weight los5 and 'thymic (immune system) atrophy. Death in laboratory
animals usually occurs many days after exposure. After subchronic or chronic
exposure to dioxin in rats or mice, the liver appears to be the most severely
affected organ. although systemic hemorrhage, edema (excess fluid accumula tion).
and suppressed thymic activity are also observed.
Animal studies have also demonstrated that dioxin is teratogenic (causes
malformities) and fetotoxic (toxic to fetus) in mice, rats, rabbits, monkeys and
ferrets and is fetotoxic in monkeys. Also, since dioxin produced, statistically
significant increased incidents of tumors in two animal species. there is
sufficient evidence to conclude that dioxin is an animal carcinogen. In fact.
dioxin is the most pot~nt animal carcinogen evaluated to date by the EPA
Carcinogen Assessment Group. For comparison, dioxin is about 50 times as
potent as the third most potent animal carcinogen evaluated (bis-chl,oromethyJ
ether) and about 50 milJion times more potent than vinyl chloride (a widely
known carcinogenic substance).
Study results concerning humans that have been exposed'to herbicides and other
chlorinated chemicals containing dioxin as a contaminant indicate that excessive
exposure leads to altered liver function and lipid metabolism, and neurotoxicity.
In addition, humans may develop skin lesions, chlorac'ne and hypcrpigmentation.
The available epidemiologic evidence concerning the carcinogenicity of dioxin in
humans is inadequate. Considering the available animal carcinogenic and
epidemiologic data, however, the overall weight-of-evidence classification for
dioxin (using EPA's interim classification scheme) is category B2. a probable
hum:!n c:!r.:inogen.
.
9
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Polychlorinated dibenzo-p-dioxins are a class of chlorinated tricyclic aromatic
hydrocarbons consisting of twO benzene rings connected by a pair of oxygen
atoms. According to the position and number of chlorine atoms, it is possible to
form 75 different types of chlorinated dioxins. The word "dioxins" is often used
to refer to ~his class of compounds, especially with respect to the highly toxic
:,3.7,8-tetrachlorodibenzo-p-dioxin (TCDD) that is present at Syntex, Verona.
This class' of compounds is rather' stable in the presence of heat, acids, and
alkalis. They are also chemically stable and start to decompose only at
tempera tures greater than 500 degrees Celsius; the percent of decomposition
depends upon the residence tim~' at high temperature and the proportion of
oxygen in the heated zone.
Physico-chemical properties suggest .that dioxin will adsorb tightly to organic
matp.;"ial in soil, resulting in low mobility. Once in the sQil, degradation processes
tend to be very slow. with half lives estimated to be ten years or longer.
Calculated and experimental results show that dioxin will concentrate in biota
present in aquatic media. Reported bioconcentration factors of dioxin in fish
range from about 2,000 to 30,000. In mammals. dioxin is readily absorbed
through the gastrointestinal tract. Absorption through intact skin has also been
reported. Absorption may decrease dramatically if dioxin is adsorbed to
particulate matter such as activated carbon or soil. After absorption, dioxin is
distributed to tissues high in lipid (fat) content; however, in many species the
liver is a major storage location. Metabolism of dioxin occurs slowly, with
metabolized dioxin excreted in the urine and feces. Unmetabolized dioxin can be
eliminated in the feces and in the milk.
\.~.: Risks to Human Health and the Environment
Continued long-term direct contact with or ingestion of soils would present the
greatest threat to human health. This exposure potential for humans can be
limited by controlling site access. Ingestion of dioxin could occur if fish
containing levels of dioxin from the Spring River were consumed or by direct
ingestion of Syntex, Verona plant soils. Wildlife (deer, turkey, rabbit) in the
slough area would be susceptible to contamination, as historically there were no
controls on animal access in this subsite area.
InhJI:1tion of dioxin-contaminated airborne particulates presents a potential route
of human ,exposure. The principal concern for inhalation of contaminated
particulates would be for Syntex. Verona employees and onsite workers during
periods of onsite construction activities involving disturbance of contaminated
soils. Mitigative measures exist to control this risk.
Ingestion of plants grown in contaminated soil represents a potential exposure
route. although there is uncertainty regardi'ng the potential for uptake of dioxin
in plant life. Dioxin uptake in many plants appears to be minimal. Thjs
potential 'pathway would be limited by controlling site access. Land use
restrictions represent another effective means of controlling this exposure
rotenti31. :l\though potential uptake in plants would be unaffected.
.
The most significant environmental problem which could be expected at Syntex.
Verona is the transport of dioxin to the Spring River due to erosion of surficia \
soils. A limited potential exists for surface contamination to reach the river b:
tr:lnspc.;t during rainfall events. particularly during periods of flooding :it th;;
10
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pl3nt site which lies in the floodplain of Spring River. The potential for
suspended contaminated sediment to reach the Spring River during normal rlo~
conditions is much lower. Stormwater is normally retained on site until it is
absorbed into the ground. .
The threat to human health and the environment due to bioaccumulation in fish
as a result of the release of dioxin from the Syntex, Verona site. appears to be
decreasing: Although fish in the Spring River have shown detectable levels of
dioxin. contaminant levels have consistently been below the advisory level of 50
ppt designa ted by the Food and Drug Administration since 1982.
I. 7.3 . Risk Assessment
A paper was published in 1984 by Renate D. Kimbrough, M.D., et aI., of the
Center for Environmental Health, Centers for Disease Control, which evaluated
acceptable soil concentrations of dioxin in residential settings. A risk assessment
was performed in this paper on the basis of several chronic feeding studies ig
rodents. The smallest lower confidence bound corresponding 50 a I X 10'
incremental cancer risk was calculated to be 28 femtograms (10.1 ) per kilogram
body weight per day (fg/kg b.w./day). This calculation was based on data for
hepatocellular carcinoma (liver cancer) and neoplastic nodules. This means that a
lifetime average dosage of 28 fglkg b.w./day would be expected to result in one
additional case of this particular type of cancer for each million individuals so
exposed. This number is based upon a number of conservative assumptions, as
discussed in the 1984 paper. Cancer in. other types of body tissues would occur at
higher dosages. On the bases of data for tissue Icss scnsi~ve than the liver, the
paper reported that an incremental cancer risk of I X 10- would be expected to
o.;.;ur at :l iifetimc dosage level of 1,4:8 fg/kg b woo/day.
Int3ke levels for residential exposure were calculated by Kimbrough, et aI., for
dermal (skin\. ingestion and inhalation exposure pathways. In residential
settings. the principal exposure pathway is through ingestion of contaminated
soil. Ingestion of soil by children is of particular concern in residential areas.
Small children may .consume soil directly during play, although inadvertent
ingestion of soil by both children and adults can also occur. The paper estimated
the average lifetime daily dose resulting from exposure to I ppb dioxin in a
residential setting to be 636.5 fg/kg b.w./day. This recommendation formed the
(o3sis for the clunup criteria of I ppb dioxin which has been applied for the
~lc3nup of residential sites.
Dioxin cleanup levels have been established for different media during cleanup
of othir Missouri dioxin sites. A cleanup level of 4 picograms per square meter
(pg/m ) has been recommended for interior surfaccs by CDC.. The action level
for dioxin in water is limited by the dctcc)ion limit, which by current methods is
approximately I ppt. A level of 3 pg/m representing the average of 14 data,
points has been used as a level of concern for airborne dioxin levels during th::
cleanup of other eastern Missouri dioxin sites.
The 1984 Kimbrough paper recommended that risk management decisions by EPA
should be based upon a consideration of the specific circumstances and exposure
oppor'tunity at each contaminated site. The paper noted that in certain
nonresidential areas, higher levels may present an acceptable degree of protection
of human health. Conversely, soil levels Icss than I ppb dioxin may be of
concern in are:lS used for certain agricultural purposes.
.
I I
-------
Potential exposure at commercia! areas. in addition to being less frequent and of
shorter duration, occurs through different primary pathways than in residential
settings. Ingestion is the principal exposure pathway of concern in residential
settings due to the potential for regular contact by small children who ma v
consume substantial quantities of soil. In certain non-residential areas there i's
less opportunity for this type of ,regular exposure by small children to occur. In
commercia'l or industrial settings where occupational exposure' occurs, direct
contact is the primary pathway of concern. The acceptable dioxin soil level is
controlled in these non-residential settings by. limiting the potential for such
contact to occur.
The Center for Disease Control. through the Agency for Toxic Substances and
Disease Registry (A TSDR) has recently provided supplemental information to the
1984 paper by Kimbrough, et. aI., in a series of correspondence between A TSDR
and EPA which evaluates ex~osure to soils contaminated at levels in excess of !
ppb in non-commercial areas. The A TSDR advisory concludes that the average
Jif~tim~ daily dosage in a commercial setting contaminated at 20 ppb dioxin is 33
fg/kg b.w./day. This calculated dosage is below the average daily dose estimated
to be of concern for public health in the 1984 article by Kimbrough. et at. In
addition, this dosage: is substantially below the estimated dosage corresponding to
residential exposure to I ppb dioxin (636.5 fg/kg b.w./day). The Agency has
therefore concluded tha t certain type:s of non-residential exposure to soil
contaminated at 20 ppb dioxin is below a level of concern for public health. The
Agency, in consultation with the ATSDR, has concluded that a remedial action at
Syntex. Verona resulting in the removal of soils exceeding 20 ppb would reduc::
the risk associated with non-residential land usage to an acceptable level.
1.8
DOCt:\1E~T A TIO~ OF SIGNIFICANT CHANGES
The selected remedy presented in this document is identical to the remedy
proposed in the EPA Proposed Plan of March 22, 1988 except for the following
determination. The Agency has determined that because this remedy wil1 not
result in. hazardous substances remaining at the plant site above health-based
levels, the five year facility review will not apply to the action at the plant
subsite areas. However, a five year review will be conducted at the Trench Area
because contamination will remain above the health-based criteria. This review
wiJl serve to a-ssure effectiveness of the remedy in the Trench Are3.
2.0 AL TER!'iA TIVES EV ALUATED
The final evaluation of the remedial alternatives presented in the Proposed Plan
were based on the subsite considered, i.c. Slough Area, Lagoon AreJ.
SpilllIrrigation Arca, Burn Area and Trench Area;' subsite location; and the levels
of dioxin detected. The primary remedial alternatives considered for all areas of
the Syntex. Verona site whiclf contain levels of dioxin greater than ~O ppb. were
I) In-place containment with vegetative cover and 2) Excavation and Therm31
Treatment. Soil sampling, using a 9S percent confidcnce level sampling protocol,
would be conducted prior to excavation of any area to establish the extent of
surface contamination. Confirmation sampling would be conducted subsequent to
excavation to verify that dioxin concentrations average less than 20 ppb. Th::
remedial action considered for the other areas containing dioxin less than 20 ppb,
was to establish and maintain vegetative covers (including topsoil as necessary)'
Those alternatives considered for each potentially affected subsite are briefl~
described in T3b,le :.1. A description of these remedial alternatives is pro\lded
..
12
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bclov. ,
:.1
r\O ACTION
AL TER!'ATIVE 1.
MAINTAIN EXISTING COt'DITIONS
The no acti'on alternative was to leave the site conditions as they currently exist..
Also. various institutional controls, (i.e. fencing and deed restrictions), were
considered under this alternative.
:.: ST ABILIZA TIO~
AL TERf'ATIVE 2. ESTABLISH AND MAINTAIN VEGETATION
This alternative consisted of seeding, mulching and fertilizing the subsite
grounds. Prior to these activities, each subsite would be backfilled as necessary
to raise the elevation to grad_~: This action was the sole remedial alternative
proposed for the "Grid" Area, the Spill Area and the Slough Area.
AL TERt'A TIVE 3. IN-PLACE CONTAINMENT
The options listed below (3A through 3D) were proposed for one or more of the
subsites. Each option proposed to keep the dioxin-contaminated soils in place
with various types of covers. The covers would be constructed to prevent
significant infiltration, promote runoff and avoid ponding.
A1~~rn:!tj\'e 3A: One-Foot Ve2etative Soil Cover
Alternative 3A was proposed for several subsite areas, i.e. Irrigation Area. Burn
Area. Lagoon Area. This option would be conducted as a sole remedy or
sutscqucnt to excavation activities, depending on the levels of dioxin in the soil
and would be followed by actions to establish and maintain vegetat.ion as
describ'ed in Alternative 2.
Alternative 3B: Rock Base with Aschalt Cover
Alternative 3B, was proposed for the Spill Area. This alternative included
pla;ement and grading of a 4 to 6 inch nominal stone layer over the existing rock
base, A four-inch layer of asphalt would be installed and maintained over the
stone base layer.
Alternative 3C: Cia v Backfill with Six-Inch Vesz.etative Cover
Alternative 3C was proposed for the Slough Area. This activity involved placing
clay in the Slough channel as a backfill material and grading the surface to
produce a gradual swale. Six inches of topsoil would then be added to support a
vegetative cover which would be established and maintained as described in
Alternative 2.
13
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A"ea
TABLE 2.1.
SUMMARY OF REMEDIAL ALTER~ATIVES
Proposed Remedial Alternatives
................ ..... ........... ........... ..... .............. ............ .......... ...... .......... ................... ..............
Crid a~ea
Maintain vegetation.
6.z~n area
No Action
Subil hat i on
Establish and meintain vegetation;
In.place containment with a one-foot veget.ted loil cover;
Removal-
Exc.vation .nd thenmll treatment. of dioxin-cont.i.fnted loils
Spi II Area
No Action
Stabi l hation
Establish and maintain vegetation;
In'place containment with an aspn.lt cover;
Deep tillage of surface soils.
Removal
Excavation and onsite burial of low level contaminlted gravel.
Irrisatic:'1 Area
No Action
Stabiliution
Establi~h .and maintain vegetation:
In.place containment with. one foot vegetated soil cover;
Deep tillage of lurface loils;
Removal-
EA:ava~ion anC ther~c~ treat~~nt of diCAin.contamina:e: sci~s
Trench Area
No Action
S:abilization
In'place containment with
soil cover:
Monitoring' Subsurface
a one foot clay cap, one foot vegetated
Lagoon Area
No Action
Subi l iution
In.place containment with a one
Deep tillage of surface soils:
Removal-
Excavation and thermal treatment of dioxin' contaminated soils
foot vegetateC soil cove~;
Slough Area
No Action
SUbilization
B.ckfill and establish
vegetation cover.
Old NEPAC:O Equipment
Clean, wipe, test, and determine proper disposal or reuse conditions.
Phctolys:s E~ui~e~~
Solvent rinse, acid rinse, water rinse, cisasse!!t:~e, i~s=!!:~,
test and determine proper disposal or reuse conditions.
\J::~
~rounc;;ate~
Install monitoring wells and assess data generated at plant site and
in Trench Area.
.
S~lve~~s end ~ashes
Hold solvents for eventual disposal. Treat aqueous washes to remove
TCDD to less than 1 ppt before evaporation.
.EA:ava~:c:~ will involve those soils containing dioxin above the 20 ppb aciten level.
-------
\
\
\
\
I
Alternati\e 3D: Gravel B3ckfil1. Twelve-Inch Clav CaD.JTwelve-Inch Ve~etated
C ~
0\ er ':
I
Alternative 3D was proposed for the Trench Area. This activity would involve:
backfilling trench depressions to the original grad e) with gravel aggregate to
provide a stable. compacted f-ill; installing a 12"' ;Iayer of compacted clay
extending' ten feet beyond the trench boundaries, sloped to facilitate run off;
installing a 12" layer of topsoil over the clay layer; and reestablishing vegetation.
AL TERNATIVE 4. DEEP TILLAGE OF SURFACE SOILS
This alternative involved inverting the surface 'soil layer to bury low level
surface contamination beneath one to two feet of soil. The tilled area would
subsequently be revegetated. Verification sampling would be performed after
tillage to confirm the absence of surface contamination.
:.3 R E\10\' AL
ALTER~ATIVE 5. EXCAVATE TOP SIX INCHES OF SURFACE MATERIAL.
BACKFILL, ESTABLISH AND MAINT AIN VEGETATION
This alternJti\'e involved the excavation of the top six inches of cover material
with a ba.ckhoe. The removed material would be disposed of onsite in other
excavated ar~as and covered with one-foot of topsoil. The excavated area would
be backfilled with topsoil to the existing grade and a vegetative cover established
as described in Alternative 2. This alternative was specifically proposed for the
S~il1 Arc:! where six inches of gravel lie atop a section of ground contamin:lted
with dioxin below 20 ppb.
ALTER~ATI\'E 6. EXCAVATION OF ALL SOILS CONTAMINATED WITH
DIOXI~ ABOVE THE :0 PPB ACTION LEVEL AND OFFSITE THERMAL
TREAT:v1E!':T
This alternative provided for excavation of all soils showing concentrations of
dioxin above 20 ppb based on the 95 percent confidence level'. The subsites
potentially affected include the Burn, Irrigation and Lagoon Areas. A backhoe
would be used for the excavation. Gravels from the Spill Area could be used as
b:!ckfill for excavated areas greater than one foot deep.
The excavated soils and debris would be placed in a dump truck. covered and
transported approximately 15 miles to the existing thermal treatment unit at the
Denney Farm Site. All ash and residues would be disposed at a State approved
landfill. This action was and remains contingent on the success of ongoing
negotiations to obtain an access agreement with the owner of Denney Farm. If
these negotiations. were not successful, then contaminated soils would be
excavated and stored onsite in compliance with the applicable EPA and State
rules and regulations.
:.4
EQeJP\1E~T R EMEDIA TJON
Old equipment originating from NEPACCO's operation and equipment used in
the onsite photolysis process remain onsite. An option to remediate this
equipment allowing future use was proposed. However, if this equipment could
not be s:!tisf:!ctorily cleaned then it would be disposed of according to the 3ctiGf.
.
15
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\
\
schcdule providcd bclow. undcr Scction 2.4.1.) Ultimatc disposal of the solutions
used in the process to clean this cquipmcnt" would be in accordance with the
Resource Conservation and Recovery Aci (RCRA) and' other applicable
regulations. /.
2.4.1 Old 1': EPACCO Eauicment-
"I
/
This equipment includes: "Cleaned-Still Detectable" equipment which was
pre\'iousl~ cleaned. retested and found to be still contaminated; "Six Tanks
Containing NEPACCO Residues" from processes attributed to NEPACCO
operations; and "Out-of-Service" equipment which has not been cleaned. It should
be noted that the residues from the "Six Tanks" have been removed, containerizcd
and stored onsitc in the Photolysis Area. The .Clean-Still Detectable" and "Six
Tanks" cquipment would be cleaned with an acid wash prior to detergent and
solvent washes. The "Out-of-Service" equipment would be cleaned with detergent
washes and' wipe tested subsequent to the approved cleaning process. The
following table indicates what action would be taken subsequent to cquipment
testing.
Level of Dioxin
Action
"\
Less tha n lOng Im-
Possible Rcuse
.,
10-100 ng/m'"
Landfill or Scrap Metal
"\
100-1000 ng/m":'
Greater than 1000 ng. m:
Foundry Disposal
Hold until proper disposal technology
is developed or reclaim using alter-
nate techniques.
Disposal of cleaning solutions would be consistent with the option proposed for
disposal and destruction of contaminated soils. These solutions would either be
concentrated or thermally treated immediately. following the cleaning process.
2.4.2 Photolvsis Eauicment
Proposed remediation of this equipment included a serie~ of solvent and aqueous
rinses; the first consisting of isopropanol or fuel oil, the second consisting of a
mixture of phosphoric or hydrochloric acid and water followed thirdly by an
acid rinse. The rinses would be initiated at the beginning of the photolysis
process and would be flushed through each piece of equipment and transfer line
which handled stillbottom residues. The rinses generated would be drummed for
eventual disposal in an approved manner, as described 'under Section 2.4.1. After
the rinses the equipment would be completely dismantled, inspected. reclean~d as
necessary and wipe tested. If the wipe test results are less than 10 ng/m- the
equipment would be stored for possible use. Otherwise the equipment would be
disposed of in the manner described under Section 2.4.1.
3.0 Sl'M~IAR\ Of THE CO~IPARATl\'E A~ALYSlS Of THE ALTER!\ATI\'ES
.
The alternatives described in Section 2.0 were evaluated J,lsing evaluation criteri3
presented in EP A Directive 9355.3~02. "Draft Guidancc on Prcparing Superfunl
De.:ision Documcnts: The Proposed Plan and Record of Decision." These criteri)
16
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. '.
"'"
relate directly to factors mandated by SARA in Section 1:1 and considerations
.... hi.:h mcasurc the overall feasibility and acceptability of the remed~. These
evaluations are summarized below.
3.1
PROTECTION OF HUMAN HEALTH AND THE ENVIRONMENT
Protection 'of human health and the environment is the central mandate of
CERCLA, as amended by SARA. Protection is achieved by reducing risks to
accept-a ble le\'els and taking action to ensure thilt there will be no future
unacceptable risks to human health and the environment through any exposure
pathway. Each remedial alternative will have different long-term and short-term
effects on the protection of human health and the environment.
All the alternatives evaluated the Proposed Plan provide some degree of
protection to public health and the environment. However, the degree of
protection and the permanence of the protectiveness vary between the
alternatives. Alternatives involving excavation of soils contaminated with
grea ter than :0 ppb dioxin would provide a high long-term degree of protection
for human health. Alternatives involving long-term management of soils left
(containing less than 20 ppb) in-place would adequately protect human health and
the environment and require regular monitoring, maintenance and the use of
access restrictions to adequa tely assure the continued effectiveness of the remedy.
Concentrations of dioxin in surface soil as high as 1380 ppb have been detected
at Syntex. Verona. While these levels represent a potential threat to public
health, there is no indication that the environment has been impaired
significantly. The primary environmental concern at Syntex. Verona is the
potcntial migration of d'ioxin into the Spring River. The Syntex, Verona site is a
relati'vely fiat area, most of which is within the 100-year flood plain of the
Spring River. The Trench Area is the only subsite not within the lOa-year flood
p13in. During rain e\:ents, stormwater generally collects in the Slough Area
where it drains to the Spring River or infiltrates into the ground.
Reducing surface dioxin concentrations from as high as 1380 ppb to 20 ppb or
less would substantially reduce any potential for harm to the environment from
contaminated soils. Maintaining existing vegetation covers over areas where
dioxin concentrations are below the 20 ppb action level. would effectively
minimize the potential for human contact and environmental impairment.
pro\ ided the continued integrity of the vegetative cover is maintained. A cleanup
lc\'cl of :0 ppb dioxin has been established for all areas of the Syntex. Verona
site. as no part of the site is considered to be a residential area. The Agency
believes that the continued non-residential usage of the .Syntex, Verona site is
assured through a combination of existing contractual and statutory controls and
practical considerations. For example, as the 20 ppb dioxin action l~vel
corresponds to non-residential land use at the Syntex, Verona site. federal and
state health ad\'isories do not allow residential use of the site. Furthermore,
Syntex, Verona is listed on Missouri's Registry of Confirmed Abandoned or
Uncontrolled Hazardous Waste Disposal. Sites. Missouri law provides that the
State must concur with a request to change the land usage of any site on this
registry. By this mechanism, the State of Missouri has control over future land
use at the Syntex, Verona site.
Concentrations of organic contaminants other than dioxin have been detected at
the S~ ntex. Yerona site.. Howe\cr. the le\els of surfacc soil contamination for
.
17
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contaminants other than dioxin'in the plant site area have been determined not
to be of concern by the A TSDR. Nevertheless, a significant quantity of those
soils will be covered or removed during the proposed remedial action presented in
this document. The Proposed Plan contemplated that additional groundwater
monitoring would be conducted at the plant site and in the Trench Area. If this
monitoring revealed that these co'ntaminants exist in the groundwater at levels of
concern the necessary remedial actions would be implemented through a second
operable unit.
In-place containment of contaminated areas by covering with vegetation would
achieve the objectives of minimizing human or animal contact with surface
concentrations of dioxin and minimizing dispersal of dioxin-contaminated soils
via wind or water erosion. The vegetative cover would be designed to remain,
effective for a specified duration. As a part of the response action, monitoring,
maintenance and institutional controls would serve to assure that the cover
integrity will be maintained. Future land-use restrictions would also serve to
protect the soil cover and prevent possible human exposure and offsite migration
of dioxin in the event of cover failure.
The thermal treatment alternative considered for excavated soils represents a
demonstrated technology capable of achieving destruction of dioxin in soils to
undetectable levels. This alternative would provide the highest level of
protection of human health and the environment because the toxicity. mobility
and volume of the materials which pose a threat to public health and the
environment would be eliminated. All dioxin-contaminated soils exceeding a .
level of concern for public health would be treated thermally resulting in the
d~struction 3nd permanent removal of dioxin from the environment.
Dust and particulates may be generated during materials handling and
prepar:Hion activities. . Measures would be taken to ensure that these potenti3!
hazards are controlled prior to full-scale operation. Workers would be protected
through measures to be outlined in the Syntex Implementation Plan, project-
specific health and safety plans and by adherence to Occupational Safety and
Health Act ,(OSHA) regulations.
The soil ex<;:avation alternative would involve transportation of dioxin-
contaminated soils to an offsite location for treatment or disposal. Spe:ia1
considerations would be required to assure the short-term protection of human
health and the environment during transport. These considerations would include:
the method of containment and transport of contaminated soil, transportation
routes and scheduling of hauls.
3.2 COMPLIANCE WITH APPLICABLE OR RELEVANT AND APPROPRIATE
REQUIREMENTS
Section l:l(d) of CERCLA, as amended by SARA, requires that remedial actions
comply with applicable or relevant and appropriate requirements (ARARs) under
Federal and State environmental laws. The following potential ARARs have
been identified and e\'alu:ncd for remedi::l1 alternatives at Syntex. Veron:!:
o Resource Conservation and Recovery Act
o Missouri Hazardous Waste Management Law
o Federal and S"tate Water Quality Criteria
o Feder3!. State. and County Transportation Requirements
.
18
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o St:! tc and County Air Pollution Control Requirements
o State and County Solid Waste Disposal Regulations
Those ARARs which have the most substantial impact on the
are discussed below.
remedy selection
3.2.1 Resource Conservation and Recoverv Act (RCRA)
. -
RCRA. as amended by the Hazardous and Solid Waste Amendments (HSWA) of
1984. regula tes the generation, transportation, treatment, storage, and disposal of
hazardous wastes as defined in 40 CFR Part 261. As of July 15, 1986, certain
dioxin-containing wastes are specifically regulated under RCRA as hazardous
wastes (the "dioxin rule," 50 FR January 14, 1985). The dioxin-contaminated soil
left in place at the Syntex, Verona site currently is not under the jurisdiction of
RCRA because the soil was contaminated prior to the effective date of the
"dioxin rule." However, RCRA may be considered applicable, relevant and
appropriate to some alternatives for remediation of dioxin.contaminated soils and
solvents or rinses generated during equipment remediation at the site. RCRA
would be applicable to the removed soil.since the act of excavation constitutes
generation of a RCRA listed hazardous waste. Also, a RCRA permit has been
obtained for the incinerator located at Denney Farm which will potentially
receive excavated soil from the Syntex, Verona facility.
Appropriate RCRA regulations must be considered for any treatment, storage or
disposal actions included i~n any of the alternatives. Onsite actions and storage
of dioxin contaminated soia (in the event that excavated soils are not incinerated
at the Denney Farm site) performed under the authority of Section 106 of
CERClA are exempt from obtaining RCRA permits; nevertheless, the substantive
pro\ isions of the permitting requirements must be met. In addition. RCRA
requirements would pertain to any off-site management of hazardous wastes in
the event that becomes necessary.
Soils contaminated with greater than 20 ppb dioxin will be excavated as part of
the selected remedy. These soils will either be transported to an offsite treatment
facility or stored onsite until such a facility becomes available. Storage of the
excavated soils if necessary, will be conducted as a temporary measure and will
not be subject to requirements specified under RCRA Section 264.
The RCRA program is delegated to the .State of Missouri, with the exception of'
HS\\'.-\ regulations. The Missouri Hazardous Waste Management law is nearl:
identical to RCRA in the regulation of dioxin wastes.
Delisting: RCRA allows for the "delisting" of hazardous wastes if it can be
demonstrated that the waste no longer meets t~e criteria for which it was
originally listed as a hazardous waste. Decontamination wastewaters, landfill
leachate. and incinerator residues (ash, flyash, and scrubber blowdown) must be
delisted if they are to be. disposed of as nonhazardous waste. Residues from the
incineration' of dioxin wastes are specifically listed as "toxic" hazardous waste
F028, until delisted.
The dclisting process normally entails preparing a delisting analysis using :1
contaminant migration model (51 FR July 29. 1986) for assessing migration
potential. A formal delisting petition is generally required for non-CERClA and
offsite CERClA actions. A delisting petition is approved by the EPA
.-\dministr:ltor and requires a rule change to formally "delist" a haz:lrdous \\'35:C.
.
19
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However. it has been EPA's policy'that in order to delist residues that are
generated from CERCLA actions that are managed onsite, these residues must
meet the substantive requirements of the delisting procedure .while not having to
meet administrative petition requirements. A formal delisting petition would be
required for residues generated from the treatment. of offsite dioxin.
contaminateu soils if the residues are to be managed subsequently as a solid
waste.
Thermal Treatment Standards: The dioxin-listing rule establishes standards for
incineration and certain types of ..thermal treatment. It states that incinerators
burning the listed dioxin wastes must achieve a destruction and removal
efficiency (DRE) of 99.9999 percent, in addition to the other standards contained
in 40 CFR 264.343 and 265.352. Residues resulting from the incineration or
thermal treatment of dioxin-contaminated soils (F028 wastes), like other dioxin-
containing wastes, must be tested to determine whether detectable levels of
specific categories of dioxins. chlorinated dibenzo-furans, and certain
chlororhenols :lr: present in the extracts from the waste or treatment residuals.
3.2.~ Clean Water Act
. Federal ambient water quality criteria (established under the Clean Water Act)
provide an estimate of the ambient surface water concentration that will not
result in adverse health effects in humans, or' the concentrations associated with
certain increrPental cancer risks. Federal ambient water quality criteria for
:.3.7.8-TCDD lare the same as the Health Advisory levels. Federal ambient water
quality criteria represent enforceable regulatory standards, and are applicable to
any altern:uive involving discharge into the Spring River.
3.:.3 Missouri Water Oualit\' Criteria
The Sta te of ~1issouri. has adopted regulator::- standards for dioxin for protection
of aqua tic life and drinking water. These standards are below analytical
detection levels. Under the Missouri water pollution regulations, dioxin is listed
as "persistent and bioaccumulative" (Missouri Water Quality Commission 10 CSR.
20-7), and discharge of any amount into the waters of the state is not allowable.
The state interprets these regulations to limit dioxin concentrations in discharges
to waters of .the state to less than the .detection level. or 1 ppt. None of the
alternatives evaluated inclu.de discharge into the Spring River. The s~ate water
quality criteria considered to constitute ARARs will be addressed in a future
operable unit if necessary. .
3.2.4 Solid Waste Discosal Reaulations
Solid waste disposal at the Syntex, Verona site is regulated by the MDNR in
accordance with' the requirements of the Missouri Solid Waste La wand
Regulations. Missouri regulations require that solid waste, in general. be disposed
. of in a landfill meeting design and operating requirements of a demolition or
sanitary landfill. A special category known as, .special waste: has been created
for those solid wastes requiring handling other than normally used for municipal
wastcs. Spe.;ial wastes are subject to waste specific disposal requirements
established on t a case-by-case basis. Incinerator ash is generally considered a
special waste. These special waste requirements may apply to the disposal of
delisted incinerator ash generated from the treatment of dioxin-contaminate
soil. or the disposal of uncontaminated structures. equipment and debris.
.
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3.3
\
\
\
I
REDCCTIO~ OF TOXICITY. MOBILITY ORI,vOLUME
':
This evalu:ltion criteria relates to the performanc~ of a technology or remedial
alternative in terms of eliminating or controlling' risks posed by the toxicity,
mobility. or volume of hazardous substances. " ,
. I
Dioxin-contaminated soil would remain in place if a containment alternative i,s
implemented. The toxicity and volume of contaminants would remain at current
levels. The stabilization by installation and/or maintenance of a vegetative
cover. coupled with dioxin's affinity for and adherence to soil particles. will
effectively minimize the mobility of dioxin.
Thermal treatment is capable of removing the dioxin from the soil and
destroying the dioxin. Thermal treatment has been proven to destroy dioxin, and
thus permanently removes the contaminant from the environment, eliminating
mobility and toxicity. The volume of the wastes, while reduced to some extent in
thc incineration process. would no longer be relevant since the wastes would no
longer be hazardous.
3.4
SHORT-TERM EFFECTIVENESS
Short-term effectiveness addresses how well an alternative is expected to
perform. the time to achieve performance and the potential adverse impacts .of its
implementation.
Of the alternatives evaluated, in-place containment of contaminated soils would
rro\ id:: the highcst Ic\ ~I of short term protection. Short-term protection is high
because implementation of in-place containment does not involve excavation or
other soil-disturbing activities which could potentially affect site workers or the
surrounding community:
Alternatives involving the excavation and subsequent management of dioxin-
contaminated soils and remediation of dioxin-contaminated equipment provide
increased opportunity for exposure to contaminants by site workers due to soil
disturbing activities. Thermal treatment alternatives would require additional
soil handling operations to render the soil suitable for the treatment process.
Worker exposure could potentially occur through direct contact. ingestion or
inhalation of contaminated soil particles and solvents or other rinses used in
equipment remediation. Measures could be implemented which would control the
potential for worker exposure during soil-disturbing and handling activities.
These measures include use of protective clothing and effective dust control.
These same measures would also assure the ~hort-term protection of the
surrounding community during periods of excavation and soil handling.
A limited potential exists for contaminants to be emitted into the air during
operation of the thermal treatment unit. The thermal treatment unit would be
equipped with redundant' safety features and operated under strict conditions
which would control the potential for any hazardous emissions from the thermal
!j:::l:m::r.! l1ni! to occur
.
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3.5 LO~G- TERM EFFECTIVENESS' A~D PERMANENCE
I
Long-term effectiveness and permanence1 addresses the long-term protection and
reliability an alternative affords. I
I
'.
In-place co.1tainment alternatives provlide an acceptable degree of long-term
effectiveness and reliability. However,lfrequent inspection and maintenance of
the cap or cover would be mandatory to assure the success of t'his alternative.
Maintenance activities including mowing, fertilizing and repair would serve to
increase the effectiveness of the .remedy. In addition, access restrictions would
be required in order to prevent possible disturbance of the cap or cover.
Thermal treatment of excavated soils provides IODg-term protection and
reliability. Thermal treatment results in the removal and destruction of dioxin in'
soil and eliminates the potential for future exposure. Fallowing completion of
thermal. treatment, no residual contamination exceeding a level of concern for
public health remains onsite. There are no ongoing maintenance requirements
necessary to ensure the continued effectiveness of the remed~'.
3.6
IMPLEME!'T ABILITY
Implement:lbility addresses how easy or difficult, feasible or infeasible. an
alternative would be to carry out from design through construction, operation
and maintenance.
The implementability of the in-place containment alternatives is affected by
technical considerations. such as availability of suitable cover materials (rock.
el:J.Y. soil and seed for; acclimated vegetation) and access to affected areas. The I
remedial design would take site characteristics into account - for instance.
because the site is in a floodplain, it may need flood-proofing in accordance with
RCRA requirements. .
Implementation of therm'al treatment involves relatively complex technologies.
These measures have been implemented successfully during the cleanup of other
Superfund sites. The time required to complete thermal treatment varies
depending upon treatment capacity. .
Routine maintenance and monitoring of the thermal destruction unit would
ensure reliability and minimize the potential for failure. If monitoring indicates
the potential for failure of the thermal destruction unit, the unit would be shut
down until corrective measures are taken. Operation of thermal destruction uni ts
has shown that they are capable of successfully destroying dioxin-contaminated
materials and are able to meet applicable or relevant and appropriate
requirementS. In addition, operation of the EPA. mobile incinerator system has
demonstrated that the residues from the treatment of dioxin-contaminated
materials can be successfully delisted.
It should be rioted that full-scale operation of transportable incineration units at
hazardous waste sites has been limited. Some such units have experienced
extended p~riods of downtime. It is possible that operation of the unit at Denne~
Farm would result in some extended downtime periods. The downtime periods
could delay the completion of thermal destruction of contaminated soils.
.
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3.7
COST
CERCLA requires that EPA select the most cost-effective (not 'merely the lowest
cost) alternative that protects human health and the environment and meets other
requirements of the law. Costs for the operable unit included in this plan will be
incurred b~: Syntex for the duration of the remedial action including the
necessary operation, maintenance and review and any additional action that may'
be determined to be necessary as a result of that operation, maintenance and
review. Cost estimates for the proposed remedial alternatives are presented in
Ta ble 3.1.
The estimates presented do not consider the potential replacement cost for
containment or disposal alternatives which may be required in the event of
failure.
3.8
COMMUNITY ACCEPTANCE
This evaluation criteria addresses the degree to which members of the local
community support the remedial alternatives being evaluated.
The local community has demonstrated favorable support for the proposed
remed~. Comments received from the responding community have focused on
implementation of the proposed remedy and the timeliness of the implementation
process. Residents attending the public meeting ind'icated support for excavation
and treatment of surface soils containing greater than 20 ppb dioxin and
maintenance of a vegetative cover over soils containing between 1 ppb and 20
p~r die,xin, .
A specific concern regarding remediation of the Slough Area was presented by
the City of Verona. A gravity flow wastewater effluent line discharges to the
Slough in the area proposed 'for remediation. It has been proposed that this
discharge line be relocated in a manner that facilitates gravity flow from the
wastewater treatment plant and allows filling of the Slough channel as specified
in the selected remedy.
One commenter expressed concern over the 20 ppb action level and the study
upon which it is based. Comments generally criticize the action level as too
consen ati\'eoand called the assumptions used on the quoted study as invalid. The
supported action level established for the'Syntex, Verona site is based upon the.
1984 report entitled. "Health Implications of 2,3,7,8 Tetrachlorodibenzodioxin
(TCDD) Contamination of Residential Soil," Renate D. Kimbrough, M.D., et.al.,
Center for Environmental Health, Centers for Disease Control (CEH/CDC). The
EPA believes that the 1984 CDC report is a valid risk assessment upon which to
base an action level. The CDC has recently supported the paper stating that no
scientific nidence has been reported in the literature to date which would
in\'alidate the assumptions upon which the 1984 risk assessment is based. or its
concl usions.
The option of removing contaminated soils from the site and transporting the
soils to and incinerating the contaminated soils at the Denney Farm site would be
acceptable to the surrounding community. To date the incinerator at Denney
Farm has received contaminated soils from other sites located in the vicinity.
This remedial alternative. removing and transporting contaminated soils to and
in.:iner3ting at the Denney Farm site. has been accepted as a preferred
.
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TABLE 3.1
ESTIMATED COST OF PROPOSED REMEDIAL ALTERNATIVE
1. STABILIZATION
A. Maintain Vegetation/In-place containment
Slough Area
510,000
5275,000
Grid Area
Trench Area
$375,000
:. R E\10\' AL
A. Excavate Gravel. Transport. Backfill, Vegetate
Spill Area
$ J 4,000
B. Excavate and Incinerate Soil, Transport, Backfill, Vegetate
J r r j g3 t j (". r. .~ r C 3
$453,000
$750.000
Burn Area
Lagoon Area
52,500,000
3. EQCIPME~T REMEDIA TIO:"
Photolysis Equipment
$300,000
$750,000
Old r\EPACCO Equipment
Soh'cots & Washes
$190.000
.
24
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(approximately 15 miles away) for thermal treatment at the incinerator located at
the Denney Farm. provided that Syntex executes an access agreement with the
owner of Denney Farm. The incinerator will remove the dioxin from the soil
and destroy the dioxin. The resulting ash will be disposed of at a state approved
landfill., The resulting wastewater will be discharged under an approved st:l te
permit.
If Syntex is unsuccessful in its efforts to reach such an agreement for the
purpose of incinerating these soils, the contaminated soil will remain onsite; soils
will be excavated no later than one year after EPA approval of the Syntex
Implementation Plan and stored onsite in accordance with the applicable EPA
rules and regulations. Clean backfill material wi1l be placed in the area of
excavation. followed by six inches of topsoil, the surface of which will be graded
for drainage. A vegetative cover will be established on the graded topsoil surface
to complete the remedial action.
~.:
SCBSITE REMEDIAL ACTIO:\
4.:.1 "Grid" Area
The average dioxin surface concentration in the -Grid- Area is 0.15 ppb; the
highest concentration is 3.1 ppb, Maintenance of the existing vegetative cover to
prevent erosion will prrvide adequate protection of the public health.
4.2.: Burn Area
The a\'erage dioxin surface concentration in the Burn Area is 6.5 ppb: the
highest concentration is 24 ppb at the surface and 27 ppb at depth. In order to
provide a remedy which is protective of the public health, all soils containing 20
ppt- or more dioxin based on the 95 percent confidence level sampling. will be
excavated up to a four-foot depth, to bedrock or to a dioxin concentration less
than the action level whichever occurs first. An estimated total of 30 cubic
yards of contaminated soils will be excavated and incinerated as described, in
Section 4.1. '
4.2.3 Soill Area
The average dioxin surface concentration in the Spill Area is 2.0 ppb; the highest
concentration is 4.8 ppb. Because this area has a 6-inch surface layer of gravel
(underlain by a 10-mil polyethylene sheet) which will not support a vegetation
cover, the gravel and polyethylene sheeting will be removed and the area will be
backfilled with topsoil The topsoil then will be reseeded with grasses to prevent
erosion, thus protecting the public health. The excavated gravel will be used as
backfill in other, more contaminated areas (such as the lagoon area).
4.:.4 Irr:iRation Area'
The average dioxin surface contamination level in the Irrigation Area is
approximatcly 4.0 ppb: the highest concentration is :9 ppb. In order to pro\'ide a
remedy which is protective of the public health, all soils containing 20 ppb or
more dioxin based on thle 95 percent confidence-level sampling will be excavated
up to a four-foot depth. to bedrock or to a dioxin concentration lessthan the
action le\'cl whichever occurs first. An estimated total of 30 cubic yards of
.
27
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a.
c.
..
TABLE 4.1
Selected Remedy for SYDtex VeroDa
AREA
Grid Area
b.
Burn Area
Spilt Area
d.
Irrigation Area -
e.
Trench Area
t
f.
Lagoon Area
g.
Slou.gh Area
h.
:\EPA.CCO Equip.
I.
Photolysis Equip.
.1.
Groundwater
k
Solvents and Washes
REMEDY
Maintain Vegetation
Excavate soils >20 ppb, incinerate,
dispose ash/residue as appropriate.
backfill with clean material, and
reestablish vegetation.
Remove gravel, backfill with topsoil.
and establish vegetation.
Excavate soils >20 ppb, incinerate,
dispose ash/residue as appropriate,
backfill with clean material, and
reesta bUsh vegeta tion.
. Backfill, grade, provide a 12" cover
and, establish and maintain vegetative
cover. Establish subsurface
monitoring of unsaturated and/or
saturated zones. Five year review.
Excavate soils >20 ppb, incinerate.
dispose ash/residue as appropria reo
backfill with clean material, and
reestablish vegetation.
Esta blish
cover.
maintain
and
vegetation
Clean, wipe test, and determine proper
disposal or reuse conditio'ns.
Solvent rinse, acid rinse. water rinse.
disassemble, inspect, wipe test, and
determine proper disposal or reuse
conditions.
Groundwater monitoring,.' remediarion
for the plant site and trench area will
be addressed in a future operable unit.
Transport solvents to RCRA permirred
facility for treatment and( or disposal
(subject to land ban), treat aqueous
washes. .
28
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contaminated soils will be excavated and incinerated as described above. in
Section 4.1,
4.2.5 talloon Area
The average dioxin surface' contamination in the Lagoon Area is 279 ppb, the
highest concentration is 1380 ppb, which exceeds the action level for industrial
and nonresidential areas. In order to provide a remedy which is protective of the
public health, all soils containing 20 ppb or more dioxin based on the 9S percent
confidence level sampling at the subsite. will be excavated up to a four-foot
depth, to bedrock or to a dioxin concentration less than the action level
whichever occurs first. An estimated total of 800' cubic yards of contaminated
soils will be exca\'atedand incinerated as described above in Section 4.1.
'"
4.1.6 SIOURh Area
The a "erage dioxin concentration in the Slough Area. is I.S ppb, the highest
concentration is 8.4 ppb. In order to provide a remedy which is protective of the
public health, a vegetative cover will be established and maintained over all soils
containing 1 ppb or more dioxin. This activity would involve placing clay in the
Slough channel as a backfill material and grading the surface to produce a
gradual swale. Six inches of topsoil would then be added to support a vegetativc
cover.
~.:,7 Trench Arc)
The average dioxin conc.entration in the Trench Area is less than 17.3 ppb; the
highest concentration is 67 ppb. These samples were composited from the surface
to a depth of 9 to 12 feet. Unlike the other'subsites which lie in the floodplain,
the Trench Area is und.erlain by a substantial layer of low permeability soils.
predominantly clay. Borings beneath the Trench Area have revealed
nondetectable levels of dioxin. Excavation of the Trench Area may result in
migration of contaminants located there as the excavation activities could disrupt
the low permeability layers beneath the subsite. For this reason, remediation of
the Trench Area, under this operable unit, will include: backfilling trench
depressions to original grade with gravel aggregate; installation of a 12 inch clay
layer that will' extend ten feet beyond trench boundaries; and subsequent
installation of 12 inches of topsoil to support a vegetative cover. In addition. a
gravel, drainage-interception trench will be installed upgradient of the trench
area. A five year review wilt be conducted at the Trench Area because
contamination will remain above health-based criteria. This review will assure
effectiveness of the remedy in the Trench Ar.ea. Additional subsurface
monitoring, described in Section 4.2.11, will be implemented, concurrently with
this remedial action. If monitoring reveals contamination of the groundwater in
this 'area at levels of concern, additional remedial action will be implemented
through an additional operable unit.
4.2.8 Old NEPACCO Eauicment
This waste unit comprises process equipment at the Syntex, Verona site which is
contaminated and requires remedial action. Some of the equipment was cleaned
but still has detectable dioxin surface contamination. The contaminated
equipment will be cleaned using an acid wash followed by detergent and solvent
washes. Equipment cleane.d to less than 10 ng/m2 may be released for' reuse.
.
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while equipment still contaminated to greater than 10 ng/m2 must be disposed in
accordance with RCRA requirements. Treatment and disposal of the solvents and
wash solutions is discussed below. This remedy will protect the' public health and
the environment.
4.2.9 Photol\'sis System
The photolysis equipment used to degrade dioxin in the still bottom wastes f'rom
tank T -1 will be decontaminated using solvent and aqueous washes. After
washing. the equipment will be completely dismantled 2and inspected. If wipe
tests indicate surface contamiaation less than 10 nglm the equipment may be
released for reuse. Otherwise, the equipment will be disposed in accordance with
RCRA requirements.
.,
4.:.10 Soh'ents 'Washes
All solvents used during the remedial activities will be collected and 5hipped for
treatment and/or disposal at a RCRA permitted facility. Aqueous washes from
equipment cleaning processes will be treated to remove dioxin. using a
proprietary Syntex process. The effluent water from the treatment process
having a diox.in concentration of less than 1 ppt will be treated by evaporation.
Any filter cake or carbon materials generate,d by the treatment process will be
transported to a RCRA-permitted facility for treatment and/or disposal.
4.:.1 J Grou nd \l.'a ter .
Activities under this fir.st operable unit will not include remediation of the lo=al
groundwater as the EPA at this time does not have sufficient data on which to
determine groundwater remediation needs. Efforts to assess and monitor the
lc.:al and arca ground waters will be initiated concurrently with implementati0r.
of this plan. If data generated from this monitoring shows contamination of the
groundwater at levels of concern, remediation of the groundwater will be
conducted through a second operable unit. This assessment and monitoring effort
will include the installation of groundwater monitoring well clusters in the
Trench Area and upgradient and downgradient of the plant site.
4.:.1: SNin2 River
Efforts to monitor Spring River fish and sediment will continue as specified' in
the Syntex, Verona Fish and Sediment Sampling Plan. As with the groundwater.
if data generated during the monitoring activities reveals contamination at levels
of concern, remediation of the Spring River will be conducted through an
additional operable unit.
4.3
RE!\1EDY SUMMARY
.
The remedy selected under the first operable unit for the Syntex, Verona site will
address only the dioxin-contaminated soils, equipment and debris at the facility.
Spring Ri\ cr and 10'::11 groun.;1w:1tcr remediation at the plant site :1na i,r. t!;':
Trench Area. if determined to be necessary by the EPA, will be addressed in a
second opcrable Jnit. The selected remedy represents a combination source-
control and stabilization measure for dioxin-contaminated materials at the site,'
A fi\ e year re\'iew will be conducted at the Trench Area because contamination'
will remain above health:based criteria. This review will assure effectiveness of
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the remedy in the Trench Area.
A site-specific action level of 20 ppb has been established. as an appropriate
cleanup level for Syntex, Verona. This action level will result in the excavation
of approximately 860 cubic yards of dioxin-contaminated soil from Syntex.
Verona which will be transport.ed and treated thermally at the Denney Farm
incinerator or stored onsite in accordance with applicable E-PA rules and
regulations. The thermal treatment process utilized in the treatment of excavated
soils will result in the removal of dioxin from the soil and destruction of the
dioxin. The residue ash from the treatment will be proposed for delisting and
disposed as a solid waste at an approved location. Following implementation of
the described action, access restrictions will be maintained at the site.
5.0 ST A TUTOR Y DETERMINATION
Based upon available information, the selected remedy satisfies the remedy
selection requirements under CERCLA, as amended and the National Contingency
Plan. The selected remedy at the site is protective of public health and the
en v iron men t, satisfied all iden tified applicable or relevant and appropriate
environl!lental requirements and is cost-effective. Federal and state health
officials have determined that removing all soils exceeding 20 ppb dioxin in
industrial or nonresidential areas, and establishing and maintaining vegetation
covers over all soils containing less than '20 ppb dioxin at the Syntex, Verona site
will adequately achieve protection of public health.
The selected remedy under the first operable unit at the Syntex, Verona site
provides protection of the environment by preventing the mobilization of dioxin-
con tamina ted soils by erosion and by removing and treating soils contaminated in
excess of the 20 ppb action level. Erosion is prevented .in soils having dioxin
concentrations below the action level either by maintaining existing vegetative
co\erS or by establishing new vegetative covers. On the basis of existing data.
the Syntex. Verona site is not a significant source of dioxin to the Spring River.
The vegetative covers will ensure that the potential for transport of dioxin into
the Spring River is no more than the existing non-detectable rate and that the
direct contact exposure pathway is controlled for area wildlife. Prior
investigations have detected no release of dioxin through airborne or
groundwater p~thways.
The estimated costs of the entire project potentially includes costs of excavation,
transportati --'. treatment, providing soil backfill and vegetative covers,' cover
maintenan;: .nd verification sampling. Costs of the remedy largely depend on
the volume of soils excavated and costs of thermal treatment. The potential total
costs for cleanup of the site is approximately $S.62 million. Inclusion of the soil
volumes excavated from the Syntex, Verona site in the other total volumes
estimated for transport to the Incinerator Unit at Denney Farm will promote
considerable cost savings.
The thermal treatment alternative presented in this document for soils containing
more than 20 ppb is the only implementable alternative identified which is
protective and. attain federal and state environmental. and public he31th
requirements. The thermal treatment alternative also satisfies the statutory
preference under SARA for remedies which reduce the toxicity, mobility, or
volume of hazardous waste and utilize alternative treatment technologies to the
m3ximum extent practic3ble.
.
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RESPONSIVENESS SUMMARY
RECORD OF DECISION
FOR
FINAL MANAGEMENT OF
DIOXIN-CONTAMINATED SOIL
AND EQUIPMENT AT
SYNTEX AGRIBUSINESS, INC.
VERONA, MISSOURI
Prepared by
U. S. ENVIRONMENTAL PROTECTION AGENCY
April 29, 1988
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RESPONSIVENESS SUMMARY
. Record of Decision for
Final Management of Dioxin-Contaminated Soil and Equipment Syntn
Ag"ibusiaess, lac.
Veroaa, Missouri
This Responsiveness Summary presents responses of the Environmental
Protection Agency (EP A) to public comments received regarding the proposed
remedial actions for dioxin-contaminated soil and equipment at the Syntex
Agribusiness. Site in Verona, Missouri.' This document addresses all comments
received by the Agency during the public comment period conducted as part of the
remedy selection process. Several additional comments were received by the
Agency following the close of the public comment period. All such comments
received prior to publication of this responsiveness summary have also been
addressed.
Commen ts to the EP A documents listed below in reference to the S yn tex,
Verona Proposed Plan, were also received during the public comment period.
These documents and commentS to these documents are hereby incorporated by
reference into the Administrative Record.
1.
...
3.
4.
5.
September 4, 1986 on the Draft Minker/Stout/Romaine Creek
Feasibility Study. ("Draft M/S/RC FS").
March :6, 1987 on the Draft Times Beach Remedial
InvestigationiFeasibility Study ("Draft Times Beach RIFS").
September 18, 1987 on the Proposed Plan for Interim Management of
Dioxin-Contaminated Sediment, Romaine Creek Portion of the
Minker/Stout/Romaine Creek Site (August 1987); on the Public
Comment Draft Operable Unit Feasibility Study, Romaine Creek
Portion of the Minker /Stout/Romaine Creek Site (July 8, 1987); on
the Proposed Plan for Interim Management of Dioxin-Contaminated
Sediment, Stout Portion of the Minker/Stout/Romaine Creek Site
(August, 1987); and on the Public Comment Draft Operable Unit
Feasibility Study, Stout Portion of the Minker /Stout/Romaine Creek
(Site (July 8, 1987) ("M/S/RC OUFS").
Mauh.-H. 1988 on the Public Comment Draft Proposed Plan for
Final Management of Dioxin-Contaminanted Soil and Final
Disposition oC Structures and Debris at Times Beacb, Missouri and
the Minker/Stout/Romaine Creek Site, Missouri ("Times Beach
Proposed Plan").
"Draft Toxicological ProCile for 2,3,7,8-Tetrachlorodibenzo-p-dioxin,"
Agency for Toxic Substances and Disease Registry, November 1987.
INTRODUCTION
On March 21, 1988 EPA announced its Proposed Plan for the cleanup of the
Synte~ Agribusiness, Inc. site in ycrona, Missouri. Under the Proposed Plan, soils
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containing greater than 20 ppb dioxin, as confirmed by the 95 percent confidence
level sampling- protocol, would be excavated and treated offsite. A vegetative
cover would be established and maintained over soils contaminated with between I
ppb and 20 ppb dioxin. Remediation of the Trench Area would include
installa tion of a vegetative clay cap and an upgradient gravel, drainage-
interception trench. In additi~n, dio~in-contaminated equipment would be cleaned
through a series of rinses. '
A cleanup level of 20 ppb dioxin has been established for the Syntex,
Verona site by EPA on the basis of. recommendations from Federal and State
health agencies. This cleanup level is appropriate for the Syntex, Verona site and
is consistent with the current. and future land use of the site as an industrial
facility. Future land use at the Syntex, Verona site will be controlled through
institutional measures including placement on the Registry of Confirmed
Abandoned or Uncontrolled Hazardous Waste Disposal Sites and site access controls
and restrictions. These controls will assure that the proposed cleaJ:l,up of the
Syntex, Verona site continues to surpass all criteria for the protection of human
health and the environment.
Activities conducted under the Proposed Plan will not include remediation
of the local groundwater at the plant site and in the Trench Area as the EPA at
this time does not have sufficient data on which to determine groundwater
remediation needs. Efforts to assess and monitor the local and area ground waters
will be initiated concurrent with the Proposed Plan. In addition sampling and
analysis of Spring River fish and sediments will continue as required. If data
generated from this 'monitoring shows contamination of the groundwater or Spring
River at levels of concern remediation will be conducted.
PUBLIC PARTICIPATION
On ~1:lrch 21, 1988 'the Agency released the Syntex "Remedial Alternatives
Report" and the EPA "Proposed Plan for Final Management of Dioxin-
Contaminated Soil and Equipment at Syntex, Verona." A public meeting to discuss
the Syntex Report and EPA Proposed Plan was held on March 29, 1988. The public
comment period on the Syntex Report and EPA Proposed Plan was concluded April
22, 1988.
This Responsiveness Summary represents a component of the Record of
Decision (ROD) package, which also includes the ROD declaration, ROD summary
and index to the administrative record. Formal selection of the remedy to be
implemented for the Syntex, Verona site occurs by signature of the ROD,
declaration by the Regional Administration for EPA Region VII.
Following the ROD signature an Implementation Plan will be prepared by
Syntex. This plan will include the design details for implementation and
maintenance of the selected remedy. A review of the Syntex Implementation Plan
will be conducted by the Agency to assure compliance with the stlected remedy.
Implementation of the remedy will commence upon approval of the Syntex Plan by
the Agency.
The following are summaries of comments received in response to the Propo~ed
Plan and the Agency's response to these comments.
'II1II
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EP A received several comments pertaining to health issues
addressed io the Drart Times Beach Remedial
Iovestigatioo/Feasibility Study, the Mioker, Stout Romaioe
Creek Operable Voit Feasibility Study aod the Times Beach
Proposed Plao.
The supported action level established for the Syntex, Verona site is based upon
the 1984 report entitled, -Health Implications of 2,3,7,8 Tetrachlorodibenzodioxin
(TCDD) Contamination of Residential Soil; Renate D. Kimbrough, MD., et.al.,
Center for Environmental Health, Centers for Disease Control (CEH/CDC). The
EP A believes that the 1984 CDC report is a valid risk assessment upon which to
base an action level. The CDC has recently supported the paper stating that no
scientific evidence has been reported in the literature to date which would
invalidate the assumptions upon which the 1984 risk assessment is based, or its
conclusions. Additionally, responses to specific inquiries and comments to the
Times Beach and M/S/RC documents will be presented in the Times Beach
Responsiveness Summary. EPA will respond to these comments which in general
pertain to health issues and the basis for the stated action level at the Syntex,
. Verona site. '
EP A received commeots to the Drart Toxicolollcal Profile for
2,3,7,8- Tetrachlorodibeozo-p-dioxio. ,
This document is currently in'draft form and has not provided ~ basis :on which
decisions were made at the Syntex, Verona site. EPA has based:its decisions at the
site on the 1984 risk assessment conducted by Kimbrough, et.al.:' The Ctnter for
Disease Control has recently reaffirmed its support of the assumptions and
conclusions presented in tho 1984 study. It should be noted that the Draft profile
presents a compilation of information on the physical, chemical and toxicological
properties which have been provided in the currently available literature.
Comments to the draft profile will be forwarded to the A TSDR and will be
incorporated into t~e Administrative Record for the Syntex, Verona site.
EP A received a commeot requesting clarification on the land
use restrictiODs aeeded for the proposed cleaDup.
EPA has recognized the need to provide institutional controls and access
restrictions at the site to assure the effectiveness of the selected remedy. These
controls will include deed restrictions and maintenance of the site on the State of
Missouri -Registry of Confirmed Abandoned or Uncontrolled Hazardous Waste
Disposal Sites-. In addition, plant site access is restricted by a perimeter fence and
during periods of pIartTshut down a 24-hour guard is provided. Subsite access will
be further restricted by perimeter fencing. Additional'restrictions necessary for
the protection of the soil cover will be provided in the Syntex Implementation
Plan.
EP A was asked what erosioD protectioD would be provided to
assure soil stability ia areas coataiDiDI less thaD 20 ppb
dioxio.
Details on the operation and maintenance of the selected remedy including
maintenance of the vegetative soil covers will be provided in the Syntex
Implementation Plan. The Syntex PJan will be reviewed and approved by EPA
prior to implementation.
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In 1986, the Centers for Disease Control provided to Congress a "Detailed Response
to Subcommittee Questions on Dioxin." In their response to a question on the
. current extent of knowledge concerning the human health effects, CDC stated that:
"A number of epidemiology studies and health
assessments in humans have given negative
.results. For various reasons, the results
of these negative studies are not convincing,
particularly because of the overriding effects
of confounding variables."
CDC further states that:
"The lack of definitive human data forces the
use of animal data for predicting pcssible
human health effects." . ;'.
'( .
and:
"
,
,
"... in the absence of useful human data: to
the contrary, prudent public health pOlicy
dictates an assumption that humans could
suffer effects similar to those observed in
animals and that preventative public bealth :
I
policy must be based on available ani.nal
data."
The 1984 risk assessment which supports the recommendations for cleanup levels at
Syntex, Verona is based upon animal health studies. This assessment has been
consistently applied during the cleanup of dioxin sites in Missouri, and remains
valid for remedi:1tion of the Syntex, Verona site.
A commenter asked if there was conclusive evidence regarding
dioxin's risk acceptability. EP A was asked if the toxicity of
dioxin to bumans, apart from chloracne, has been demon-
strated.
There is disagreement in the scientific community regarding the risks due to
, exposure to dioxin. The position of EPA is to take a conservative approach to
ensure that any error made in the assessment of risk is made of the side of safety.
CDC has recently affirmed support of the 1984 health assessment that established
the original action level for exposure to dioxin in a residential setting. There has
been no scientific evidence presented to date that invalidates the 1984 assumption
of conclusions.
The EP A received a comment concerning the Proposed Plans
statement that TCDD is the most potent animal cardnolen
evaluated to date by the EPA Carcinolen Assessment Group.
The commenter said that this statement is misleading and
inappropriate. The commenter further stated that TCDD is
not a potent cardnolen if one considers its carcinolenic:ity
relative to its acu.te toxicity.
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A commenter expressed concern regarding what effect the
proposal to (ill the Slough subsite area with clay might have
on the presence o( the City o( Verona wastewater out(all.
The Syntex Implementation Plan will address this issue. The gravity flow
wastewater outfall can be relocated to a point in the slough, downstream of the
proposed filli~g activity. in a mannet' th.at facilitates gravity flow from the
wastewater treatment plant and allows filling of the slough channel as specified in
the selected remedy.
EP A was questioned regarding the risk posed by the levels o(
dioxin left onsite. The commenter expressed concern over the
continued transport o( dioxin to the Spring River.
The clea'nup levels discussed in the proposed plan were established for the Syntex,
Verona site based upon recommendations from state and federal health agencies.
Sampling and analysis of the Spring River fish and sedime.nts will be continued as
appropriate to monitor the short and long effects associated with the site and
.implementation of the selected remedy. EPA feels that these monitoring efforts
will provide the necessary information to assure protection of the public health
and environment.
EPA received a comment indicating concern over
implementation o( the remedy without more knowledge on
factors affecting transport of dioxin contaminated soils and
on mechanisms of dioxin transport to the Spring River.
The selected remedy will se.,rve to remove the major sources of dioxin presently
onsite and stabilize areas containing dioxin below the action level. These
measures in adjition to the necessary maintenance will assure longevity of the
selected remedy and reduce if not eliminate potential dioxin transport to the
Spring River. Continuing the sampling and analysis of the Spring River fish and
sediment will allow the Agency to assess the effectiveness of the remedy as to
residual dioxin concentrations left onsite.
Sampling at the Syntex, Verona site and at other Missouri dioxin sites has
indicated that the dioxin is tightly bound to soil particles, and that migration of
the dioxin is directly related to the transport of the contaminated soils. The EPA
does not believe that the dioxin contamination at the Syntex, Verona site
represents a significant threat to groundwater or air quality on the basis of
previous extensive sampling. Groundwater samples have to date been found to
contain nondetectablc.:values with a detection limit of I part per quadrillion
(ppqd). Sampling of sediment and biota in the Spring .River have indicated
decreased concentrations over the years sampled and with distance away.
downstream of the site.
EP A was asked if a deep tillage/soil inversion technique could
be used as the remedy (or areas containing Crom 1 to 20 ppb.
This alternative was considered by EPA, however it was determined not to
appropriate .at the Syntex, Verona site for areas containing from I to 20 ppb.
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A commenter suggested that all alternathes including the no
action alternative, presented in the "Remedial Alternatives
Report" would adequately protect the public health and the
environment. The commenter further stated that flaws exist
iD the assumptions used to establish an action level and that
recent scientific advances were not considered.
An action leve'l of 20 ppb dioxin was established fo'[ the Syntex, Verona site based
upon the 1984 report entitled, "Health Implications of 2,3,7,8
Tetrachlorodibenzodioxin (TCDD) Contamination of Residential Soil," Renate D.
Kimbrough, MD., et.al., Center for Environmental Health, Centers for Disease
Control (CEHjCDC). The CEHjCDC has recently supported the 1984 paper stating
that no scientific evidence has been reported in the literature to date which would
invalidate the assumptions upon which the 1984 risk assessment is based, or its
. conclusions. '
ODe commen ter recommended that the site be lef.t as it is for
the time being since the health effects 01 dioxin to humans
are not thought to be sigDiticant.
The no action alternative is not considered by EP A to be acceptable for the site;
the potential for exposure would continue to exist. A longterm remedy that is
compatible with regulatory requirements and provides protection of human health
and the environment must be selected. Accordingly the no action is not considered
to be a satisfactory selection.
EPA received comments which disputed the information
presented iD the Proposed Plan on tbe toxicological effects of
dioxin in humans. '
The literature contains a nu.mber of human health studies which draw conflicting
conclusions. A number of these studies were cited by the commenter. The
commenter states that "of greatest significance is the study performed on 104 res-
idents of Times Beach" conducted by CDC, Missouri Division of Health, St. Louis
U ni versity, and St. Joseph's Hospital. This article actually states:
"The results appear negative, but no overall
definitive conclusion should be based solely
o~ this initial ,study."
The article further states:
"Public health policy in situations such as this
environmental contamination with TCDD must
continue to focus on -the prevention of any
potential health effects (particularly delayed
or long-term), even if effectS are not demon-
strated in a pilot study. For this reason
appropriate efforts to prevent human exposure
must continue, in this and other similar
situations, until a more complete under-
standing of public health risks is obtained."
.
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The sta tement made in the proposed plan is technically correct. When considered
on a unit risk basis, the cancer potencies of different chemicals can be compared.
On the basis of a relative potency index of the 55 chemicals that CAG has
evaluated, TCDD is the most potent carcinogen.
The commenter questioned the Proposed Plans statement that
TCDD is 50 times as' poteni as. BCME Is Irrelenat slace
exposure to BCME at oae polat was relathely commoa ia
several of the chemical ladustries yet exposure to TCDD is
rare. la addltloa, the commeater stated that there still is ao
evidence that TCDD is a humaa carciaolea after 40 years of
workpiace experieace with It.
It is suggested by the commenter that there is no evidence that TCDD is a human
carcinogen after 40 years of workpiace experience. The commenter also
acknowledged, however, that exposure to TCDD in the workplace is rare. The
potency of TCDD relative to BCME is relevant and technically correct.
A commenter questioaed the use of the EPA 95 perceat
coaCideace level samplial protocol, as compared to other
similar samplinl procedures.
The 95 percent confidence level sampling protocol required by EPA has been
extensively peer reviewed and approved by state and federal health and
environmental agencies. The EPA sampling protocol has been incorporated into
cleanup and sampling plans for all other Missouri dioxin sites that have
successfully been remediated or which are currently undergoing remediation.
EP A was asked to clarify the propos.ed exteat of excuatloa.
Subsite areas which previously were found to contain greater than the 20 ppb
dioxin action level will be resampled using the 9S percent confidence level
sampling protocol. Those areas found to exceed the action level will be excavated
in stages or lifts using either a backhoe or other excavation equipment determined
to be the most efficient and cost effective. The excavation activity will proceed
until 1) levds of dioxin are below 20 ppb, 2) bedrock is reached, or 3) the four
foot depth 1S reached. Excavation will not proceed below bedrock or the four foot
depth.
A commenter stroally sUilested that dioxia-coatamlaated soils
remaia ia-place uatil a treatmeat techaololY becomes
anilable, fifthe eveat soils caaaot be treated at the Deaaey
Farm IDclDeratioD UDit. ID additloa, tbe commeater coateads
tbat storale .oDsite subsequeat to excuaUoa creates tbe Deed
for double-haadlial aad iacreases the poteatial for humaa
exposure.
EPA has provided that all soils, contaminated with dioxin above the 20 ppb action
level, be excavated within one year after Implementation Plan approval.
Exca vation within the stated schedule is necessary to assure a timely completion of
the remedy :ind to remove those sources considered to be a threat to public health
and the environment. Containerization and storage of the excavated soils will be
conducted in accordance to applicable EPA and state rules and regulations; in a
manner that substantially reduces any threat to the public health or environment.
.
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EPA was asked whether dioxin-contaminated soils excavated
from the Syntax, Verona site would be treated at the Denney
Farm incineration unit. The commenter suggested that there
were a number of impediments to implementation of the
proposed remedy.
EPA is currently working toward an agreement with the appropriate parties which
will facilitate treatment of the excavated soils at Denney Farm. In the event these
negotiations fail dioxin-contaminated soils excavated during site remediation will
be stored onsite in compliance with EPA rules and regulations until an appropriate
treatment technology becomes available.
EPA was asked what action would be taken subsequent to the
groundwater monitoring program identified in the Proposed
Plan.
The EPA at this time does not have sufficient data upon which to base future
decisions regarding groundwater remediation. The groundwater monitoring
program is an effort, in addition to the existing groundwater monitoring efforts, to
further identify the extent of groundwater contamination. At the time sufficient
data is received a determination will be made as to the appropriate response action,
based on the applicable, relevant and appropriate requirements under federal and
state environmental laws.
A commenter suggested that the reference to the Denney Farm
incineration unit's capability to successfully destroy dioxin in
soil to undetectable levels is an overstatement of the fact.
Furthermore the commentor refuted claims that the
destruction and removal efficiencies are high enough to allow
delisting of the dioxin contaminated soil following treatment.
Analysis of residues generated at the Denney Farm incineration unit have revealed
non detectable levels of dioxin, utilizing the detection limits applicable at the time
of analysis. These results demonstrate that the incineration unit at Denney Farm
is capable of removing residual dioxin to a level which will allow delisting of the
contaminated soil from the Syntex, Verona facility.
EPA received a comment questioning the past and present
process for delisting residues generated at the Denney Farm
incineration unit, the commenter further stated that the
current delisting procedures are invalid.
The 1985 delisting procedures were based on knowledge that was currently
available at the time regarding safe levels for delisting. The current model used
for delisting purposes was published in the Federal Register and is the only model
currently approved by EPA for delisting activities. The delisting of this residue is
rule making procedure separate and apart from this Record of Decision.
Comments pertaining thereto should be addressed to the EPA Office of Solid Waste
in Washington D.C.
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