NCD981927502_19980101_Geigy Chemical Corporation_FRBCERCLA ROD_ROD - Explanation of Significant Difference 1997 - 1998-OCR

EXPLANATION OF SIGNIFICANT DIFFERENCES
TO THE REMEDIAL ACTION
GEIGY CHEMICAL CORPORATION SITE
ABERDEEN, MOORE COUNTY
NORTH CAROLINA
Prepared by
RECEIVED
JAN 2 81998
SUPERFUND SECTION
U.S. Environmental Protection Agency
Region IV
Atlanta, Georgia
January, 1998
•
TABLE OF CONTENTS
SECTION
1.0 Introduction
2.0 Site Location and Description
3.0 Site History
4.0 Record of Decision
5.0 Status of Remedial Design
6.0 Rationale for ESD
6.1 Sampling Results
6.2 Analysis of Sampling Results
6.3 Additional Work Required
7.0 Statutory Determinations
8.0 Public Notification
LIST OF FIGURES
Figure 1 Groundwater Plume based on 1992 information
and Current Remediation System
Figure 2 Upper Black Creek Groundwater Plume
Figure 3 Lower Black Creek Groundwater Plume
Figure 4 Modeling Results for Pump and Treat Scenario
Figure 5 Modeling Results for Natural Conditions Scenario
Geigy Chemical Corporation Site
Explanation of Significant Differences
January 1998
PAGE
1
1
2
2
3
5
5
5
8
11
12
4
6
7
9
10
•
EXPLANATION OF SIGNIFICANT DIFFERENCES
TO THE REMEDIAL ACTION
GEIGY CHEMICAL CORPORATION SITE
ABERDEEN, MOORE COUNTY, NORTH CAROLINA
1.0 INTRODUCTION
This Explanation of Significant Differences (ESD) was prepared for the Geigy
Chemical Corporation Superfund Site ("Site"). The purpose of this ESD is to document
that the Environmental Protection Agency (EPA or the Agency) is adding additional
monitoring requirements to the Record of Decision (ROD) for the Site.
EPA previously issued the Geigy ROD on August 27, 1992. The original
requirements and goals of the August 1992 ROD are reiterated in Section 4 below.
The necessity of this ESD is based on information generated during the development of the Site's Remedial Design (RD). The new information is summarized in Section 6
below.
This ESD is issued pursuant to Section 117(c) of the Comprehensive
Environmental Response, Compensation and Liability Act (CERCLA), 42 U.S.C Section
9617(c), and the National Oil and Hazardous Substances Pollution Contingency Plan (NCP), 40 CFR Section 300.435(c)(2)(I). A copy of this ESD will be added to the Site
Administrative Record and to the Information Repository, both of which can be found in the Aberdeen Town Hall or in EPA's Region 4 Records Center. The public is
encouraged to review both the Administrative Record and the Information Repository
during normal working hours.
2.0 SITE LOCATION AND DESCRIPTION
The Geigy Site is located just east of the corporate city limits of Aberdeen, North
Carolina on Highway 211 in southeastern Moore County. The Site is approximately
one-acre and is located on the Aberdeen and Rockfish Railroad right-of-way. It is in
the form of an elongated triangle between Highway 211 and the railroad, with the
highway and railroad intersecting at the apex of the triangle.
The Site soils have been remediated; the surface of the Site has been
restorated. It currently is covered with rye grass, wild flowers, and pine trees.
Geigy Chemical Corporation Site
Explanation of Significant Differences
January I 998
• \ •
3.0 SITE HISTORY
The Site was operated :as a pesticide blending and formulation facility by various operators from approximately !1947 to 1967 and by retail distributors of agricultural
chemicals from 1968 to 1989! The pesticides DDT, toxaphene, and BHC were I received in bulk at the Site, blended with clay and other inert materials, repackaged,
and sold. Pesticides were not' manufactured at the Site, but were formulated by dry
mixing into a product suitable for local consumer use. Spills occurred during the
normal formulation activities. I
Soil removal actions wJre conducted in 1989 and 1991. In February 1989,
' visual areas of pesticide contamination were removed and the wastes placed at a landfill in Pinewood, South Ca~olina .. A total of 462 tons of material were removed and
disposed. A second removal action was conducted in 1991. Approximately 2841 tons
of soils and debris were removed. Of this, 505 tons of soils were transported to a
Texas facility for incineration. 'The remainder was disposed at a landfill in Louisiana .
. 4.0 RECORD OF DECISION
The ROD was signed on August 27, 1992, and addresses groundwater and soil I contamination at the Site. The major components of the selected remedy, as depicted
in the 1992 ROD include: 1
• Extraction of groundwater across the Site in the upper aquifer (surficial) and the
second uppermost aquifer (Upper Black Creek) that is contaminated above
Maximum Contaminant
1
Levels or the North Carolina Groundwater Standards,
whichever are more protective;
I
I
I • On-site treatment of extracted groundwater via carbon adsorption;
I
I
• Discharge of treated grtjundwater to the local POTW or an infiltration gallery.
I
I • . Continued analytical monitoring for contaminants in groundwater. I
• Demolition of former warehouse foundation; disposal at a municipal or secure
landfill; '
' • Excavation of the top foot of on-site soils contaminated above the performance
standards; :
• TCLP testing of the stockpile of contaminated soil to determine final disposition;
Geigy Chemical Corporation Site
Explanation of Significant Differences
January 1998 2
•
• Off-site incineration of contaminated soils that fail the TCLP test;
• Off-site disposal in an approved hazardous waste landfill of contaminated soils
that pass the TCLP test;
• Backfilling, grading and revegetation of excavated area;
• Additional sampling and analyses of the second uppermost aquifer to determine
the extent of pesticide contamination, and to determine if the trichloroethene
(TCE) found in two wells is site-related.
5.0 STATUS OF REMEDIAL DESIGN AND REMEDIAL ACTION
The RD was initiated on July 15, 1993. The design of the remediation activities
identified in the ROD, including the additional sampling, has been completed. The RD
was approved by EPA in March 1996.
Remedial action (RA) activities started in September 1996. The RA included:
• Removal of the remaining concrete foundations and the disposal of 2,460 tons
of debris to a Subtitle D landfill;
• Disposal of 4,475 tons of contaminated soils to a Subtitle C landfill;
• Installation of four extraction wells in the surficial aquifer and three extraction
wells in the Upper Black Creek aquifer in the vicinity of the facility property;
• Construction of a groundwater treatment facility that includes an equalization
tank and two series of activated .carbon canisters;
• Construction of an infiltration gallery (the 1992 ROD gave an option for
discharge of either an infiltration gallery or the local POTW) for discharge of
treated groundwater; and
• Installation of six additional monitoring wells and three additional piezometers.
The groundwater extraction and treatment system began operating in January
1997. In Figure 1, the extent of the groundwater plumes in the surficial aquifer and the
Upper Black Creek aquifer as identified in the 1992 ROD, along with the seven
extraction wells are shown.
Geigy Chemical Corporation Site
Explanation of Significant Differences
January I 998 3
<Elillll
--.ss... o,srr,c IICNIO'WfC #CU
,.,.__,$♦ DZSTWC CXIR/ICIICW l£U
.,._,s♦ c,rsrr,c .IIEZl. l'CWr l'l/CI'Oll//£1ER
""" CXTRACl1CW l£U nJRf:£ .-
•
flG1-IWA Y' 211
♦wW-1lS
FIGURE I
Groundwater Plume based on l 992 Information
and Current Remediation System
1-1 T $DR 11 HtlPE
" ,,
" ,, ,, ,,
" " 11l£A"'11Df'I~
I ,,
" ' ,,
"---mcAIUJ ~!CR ""°"""" UC
IA.IR,4/J(M(;NJ.£RICS
♦ WW-1&$
NORTH
f
•
•
£,(lRACllaY ANO
lREA IJl£NT SYSTEM
SllE LArrJUT
<ZlCl' ~ ctJliF'CJt41KN SIF
~ H(RIH CM'tVVA
• •
6.0 RATIONALE FOR ESD
There are three types of post-ROD changes. Depending on the extent or scope of the modification being considered, the post-ROD change is either (1) non-significant or minor; (2) significant; or (3) fundamental. A different documentation procedure is associated with each type. For non-significant or minor changes, these changes are documented by recording the change in the post-decision document file. The dissemination of a fact sheet to the public is optional. For significant changes to a ROD or RA, these changes should be documented in an ESD, as required by CERCLA and the NCP. Fundamental changes to the remedy should be documented in a ROD amendment.
EPA has determined that the changes and additions covered by this ESD constitute a significant, not fundamental change to the original scope of the remedy ?elected in the ROD. Therefore, an ESD is appropriate to document these changes.
6.1 Sampling Results
The remedy as stated in the ROD has been implemented; the soils have been remediated and the groundwater near the facility is being treated in accordance with the ROD. However, as stated in Section 4 of this document, the ROD required additional sampling in the second uppermost aquifer to determine the extent of the pesticide contamination and to determine if the TCE was site-related. This sampling was completed and the extent of the pesticide-contaminated groundwater plume was determined.
Figure 2 shows the extent of groundwater contamination identified in the Upper Black Creek aquifer. This sampling investigation also revealed that the Lower Black Creek aquifer was contaminated with pesticides. This plume is shown in Figure 3. It was also determined that the TCE was not site-related.
6.2 Analysis of Sampling Results
A Oowngradient Groundwater Remedial Action Work Plan was finalized in October 1997. This workplan details the results of the pre-RD sampling and provides extensive analysis of the-results of this sampling activity. The results of this analysis indicates that periodic monitoring of the downgradient portion of the plume along with periodic monitoring of the surface water bodies would address this groundwater contamination. This determination was based on the following:
• There are no receptors of untreated groundwater io the downgradient area, Currently, there is one private well user in this area. All other residences and
Geigy Chemical Coiroration Site
Explanation of Significant Differences
January 1998 5
N
i Legend
C:3 Pond
~ lluildin;I
/'-./ P,,.,.d Aoll<I•
Ur0pa .. 11 Roatls
/'< llailu,ads
/',,/ Si,eam
ri USGS Wei ciu.,.,
';,.::.it
, -. ~ "
~-,'' . .,. . t -.
1: ?t;, i.: ·1 ·
-,o-Total 6HC conccnu•Uon "oil (DHhell whe.r• infa,1elll
,z.·~·./;
~\{i·• Xjrf~?"
0
Rust Environment th Infrastructure
0 800 ....
SCALE IN FEET
"
SCALE IN MILES
FIGURE2
Upper Black Creek Groundwater Plume
ae,~ CHEMICJl:~l~'~r~~TION As,re
"
N
legend
~ -+ r:::::: ··-0 E::} .....
/v' -Roat• ..
lalp-Ruao:I• Ell
Wood,,d Ar••
.,TV A""'a•tl•
/v' s ........
~ US EPA Monlt"""V W.111At,,ama1e, + bo,·<1 DI Aberd...,n Municipal w.tl
f'lo,......,,e,Nllfl
Upp.r -lower -Cf.el,...,..
s1r • ..,sullt6-
Mon11 ... 1ngw.1 i-,111a<1<c...n"""""'
tot.i BHC Concen1r1Utln ~
l()ashed ,vht,,e inf&J~,
0
Rust Environment & Infrastructure
: i' J;',• .. ~ "C.c-..,
·'' ..
,oo 0 ,oo """
SCALE IN FEET
"
SCALE IN MILES
FIGURE 3
Lower Black Creek Groundwater Plume
GEIGY CHEMICAL CORPORATION SIT£
ABERDEEN NORTH CAROLIN
•
\ • •
businesses are connected to the city water system. The private well has been
sampled and the water is contaminated with pesticides. However, the Potentially
Responsible Parties (PRPs) have installed a carbon filter on the well, and
conducts periodic monitoring to ensure the proper operation and maintenance.
• The City of Aberdeen, by letter dated April 1997, informed EPA that the City
would not install any municipal water supply wells in this downgradient area
• Groundwater discharge to surface waters limits the further migration of the plume, Groundwater flow directions have been identified to verify that the
groundwater pesticide contamination plume is contained by the following creeks:
McFarland's Branch, Aberdeen Creek, Ray's Mill Creek, and Trough Branch.
• Pesticide concentrations in surface waters do not currently pose a risk to human
health or wildlife, The risk assessment for McFarland's Branch was updated ·
based on the new sampling results and indicates that the risk associated with
the downgradient plume is well below EPA's acceptable risk range of 10·4 to 1 o-6
• Groundwater modeling has shown that the concentrations of pesticides in this
downgradieot area will decrease in a time frame comparable to a pump-and-treat
system, A groundwater flow model was used to simulate the performance of six extraction wells in the downgradient plume area. The model was also used to
estimate the extent and longevity of the groundwater plume under naturally-
occurring conditions. The results of this modeling show that the plume would be
remediated in 19 years under pump-and-treat conditions (Figure 4) and would
be remediated in 25 years under natural conditions (Figure 5).
6.3 Additional Work Required
This ESD documents that the groundwater plume not currently covered by the
extraction and monitoring system will be monitored'and this monitoring, as well as other activities will be incorporated as part of the overall site remedy. The additional
remedial action activities are detailed in the Downgradient Groundwater Remedial
Action Workplan and will be conducted in addition to the current facility property
groundwater extraction and treatment system. They are as follows:
1. Natural Hydraulic Containment
Periodic measurement of water-levels will be conducted to verify that
groundwater flow patterns do not change over time. In addition, the natural
processes of dispersion, adsorption, and degradation will be evaluated by
Geigy Chemical Corporation Site
Explanation of Significant Differences
January 1998 8
_______________ ,\~\;(:~~;~ttt_.·._.>: ,;: ~
ltcducCion in Mu• uf Gamma-llllC nilh ·nmo
C1111t•c11nrnl l'umjNn~ Co11tli1lous
w
Nu Ad,.....plk>111111d Nu l)ci::rJWlllon
l..ouor 111:ock Crock l'u1uile,
,oo L---''='=-o----o "
, WP-13LB •
----:--·~M~j]._e:e;,.-.:--,
', ,~• -wi-13LT
W.11
PW-ll
ew-2L
PW-ll
PW-4l
PW-6L
PW-6L
PW-7L
Pumping Rate
!gprnJ
mo
" " " " " --'-'-
Total Ex11•c11cn Ra1a "' 2>16 gpm
Toial lnjec1ion Ra1e ~ 100 gpm UW-lll
N
Legend
~ ~
::::-J --
::~ 8uildcno
~• A.o..,s
/\/ sueom
0 US fPA
Monil"'inu WGIIIPiatoma,e,
• • WP-11~\J
, J"fL ·Y ., .(lil"i;;~~r.,;~..:_ .!}{~itifi
0 ..
Ell
M>wn at At,~rnHn Munic;p.,I Well ,.....,_,,
PlazDD>elHNnl
C.-,11t 111.:k CtHI< Aquil«
Su•-Stall~
MoA,Co,in9 W.I 1,,~,.,, OIUl:k Cn,sk Aq,.,ilcf
N•Hu:
C--b11ac-.Wio11 i.-BIKlr.C...1<,t,q..U.
eo..c.p1ua1 qaclian -i.-, BIM:k C...k Aqu11irf
1.""'-1••-••--U_, _ _,,, __ l>y
D'A dwino li.l'! .116 -~-
. -~;::..~:~:t1
' • 'WP 13
, ,MeF.~,. 14
', ./, -~~-tl
PUMPING CONDITIONS '"° 0 '"° 1000
NO ADSORFTflON, NO DEGRADATION
Rust Environment&. Infrastructure
SCALE IN FEET
FIGURE 4
Modeling Results for Pump and Treat Scenario
GEIGY CHB.'JCAL coRPORATION SITE ABEAOEEN, NORTH CAROLINA
•
ll•<1~~1i1>1, ,,. .l,hss <>I c ......... uttcm,1, n ....
rtt1poud R•Nlf<l) Ca11dld1m,
,0
Na Ad>orp,i..,1 a11d /'111 lnj:n,dalloor.
l..01to1· Dia<~ c,~.~ A~ullor
, __ , ,-
N
Legend
CE] Pond
~' llulldong
/'V l'awdADa<lo ---
0
121 USEAII
Monitorinv WwlllPIHomele<
........,.., ... _Mu,,iapal_ /\I' a-.atte-.-.u..10.20~·
.,..nal Miudua~Vwl 1.-.-dl
Ploci-i..-1..ow ... BIKk CrHk Aqulle<
suums1o110_..
Mon11..-lng W.I
L-•Bllw:l<C...t......_, ------~"_,....,...__....~ EPl'< ...... U4.IG~
PROPOSED REMEDY CONDITIONS
NO ADSORPTION, NO DEGRADATION
Rust Environment lb. Infrastructure
,oo
•
0 800 '800
SCALE IN FEET 10-SEP-1997
FIGURE5
Modeling Results for Natural Conditions Scenario
GOOY CHEMICAL CORPORATION SITE
R O A I A
• • I
updating the groundwater model with monitoring well data as it is collected to determine its effectiveness.
2. Groundwater Monitoring
Periodic groundwater monitoring of select existing and proposed monitoring
wells and piezometers. Monitoring locations and frequencies will be reevaluated every year for the first five years and every five years thereafter.
3. Surface Water and Stream Sediment Monitoring
Periodic surface water sampling and stream sediment sampling will be
conducted in McFarland's Branch, Aberdeen Creek, Ray's Mill Creek and Trough Branch.
4. Water Supply Protection
Municipal Water Supply Well Number 2 of the Town of Aberdeen's water supply system will be monitored to ensure that the well is not adversely affected by Site
contaminants. Residential well protection will be accomplished by well permit application reviews, drive-through surveys of the downgradient area and
informal interviews with residents to determine if new residential wells have gone
into service. The one residential well currently in this area will continue to be supplied with a granular activated carbon filter and will be monitored to ensure that the treated water meets Federal and State drinking water standards.
5. Periodic Remedy Reviews
Periodic remedy reviews will be conducted to evaluate the effectiveness of the
remedial action. The remedy reviews will focus on evaluating the protection of potential receptors and the effectiveness of the remedy with respect to forecasted concentration trends in the groundwater.
7.0 STATUTORY DETERMINATIONS
EPA has considered the new information that has been developed and the
addition made to the selected remedy by this ESD and believes that the remedy selected in the ROD remains protective of human health and the environm'ent, complies with Federal and State requirements that are applicable or relevant and appropriate to this remedial action, and is cost-effective. In addition, the remedy utilizes permanent solutions and alternative treatment technologies to the maximum extent practicable at this Site.
Geigy Chemical Corporation Site
Explanation of Significant Differences
January I 998 I I
• •
8.0 PUBLIC NOTIFICATION
In accordance with Section 117(c) of CERCLA, EPA published a notice of the ESD in the local newspapers, which describes the ESD and its availability for review. An ESD Fact Sheet was also prepared and mailed out to the persons on the Site
mailing list. A 30-day public comment period was also held from November 13, 1997 to December 13, 1997. No comments were received.
"Richard D. Green
Acting Director
Waste Management Division
Geigy Chemical Corporation Site
Explanation of Significant Differences
January 1998 12
• NORTH CAROLINA DEPARTMENT OF
ENVIRONMENT AND NATURAL RESOURCES
Ms. Giezelle Bennett
Remedial Project Manager
January 23, 1998
US EPA Region IV, North Superfund Remedial Branch
61 Forsyth Street, Eleventh (11) Floor
Atlanta, Georgia 30303
DIVISION OF WASTE MANAGEMENT
RE: Concurrence on The Second Draft Explanation of Significant Difference
to the Downgradient Groundwater Remedial Action Work Plans
Geigy Chemical Corporation Site
NCD 981 927 502
Aberdeen, Moore County, NC
Dear Ms. Bennett:
The Explanation of Significant Difference (ESD) to the Downgradient
Groundwater Remedial Action Work Plans (RA WP) dated October 1997 for the Geigy
Chemical Corporation Site, located in Aberdeen, North Carolina has been received and
reviewed by the North Carolina Superfund Section. This ESD and the associated RA WP
fully comply with the NCAC 2L Groundwater Standards under Section . 0106 Paragraph
(I), natural attenuation processes, when proper public notification is fulfilled. The State
concurs with the ESD changes to the original ROD for the proposed RA WP subject to
the following conditions.
I . State concurrence on this Draft ESD and the selected remedy changes for
the site is based solely on the information contained in the Draft ESD
dated October 1997. Should the State receive new or additional
information which significantly affects the conclusions or remedy selection
contained in this ESD, it may modify or withdraw this concurrence with
written notice to EPA Region IV.
2. State concurrence on this Draft ESD in no way binds the State to concur
in future decisions or commits the State to participate, financially or
otherwise, in the clean up_ of the site. The State reserves the right to
review, overview comment, and make independent assessment of all
future work relating to this site.
401 OBERLIN ROAD, SUITE 150, RAL.EIGH, NC 27605
PHONE [phone] FAX [phone] Ci!m1l.lo/; ·'tC·'·&®-#,j;j.1;;~ AN EQUAL OPPORTUNITY/ Al'"FIRMATIVE ACTION EMPLOYER· SO% RECYCLED/I 0% POST-CONSUMER PAPER
Ms. Bennett
1-23-98
Page 2
• •
3. If, after remediation is complete, residual contamination in groundwater exceeds
NCAC 2L Groundwater Standards the State may require deed recordation/restrictive
covenants to document the presence of the residual groundwater contamination and
possibly limit future well permits or groundwater use in this area as specified in NCGS
130A-310.8 and 130A-310.3 as amended by Senate Bill 125.
The State of North Carolina appreciates the opportunity to comment on the Draft
Explanation of Significant Difference for the subject site, and we look forward to working with the
EPA on the final remedy. If you have any questions or comments, please give me a call at, (919) 733-
280 I, extension 341.
s;;cely, JJJ /
o~hcilson ;-
' Remediation Branch Head
Superfund Section
cc: Phil Vorsatz, NC Remedial Section Chief
Jack Butler, NC Superfund Section Chief
Michael Kelly, Deputy Division Director
Randy McElveen, NC Superfund Section
I
. ... . RoD· EXPLANA(}PN OF SIGNIFICANT DIF.ENCE FACT SHEET
. GEIGY CHEMICAL CORPORATION SUPERFUND SITE
Aberdeen, Moore County, North Carolina
Region 4
November 1997
This fact sheet is not to be considered a technical document but has been prepared to provide the general public with a better understanding of activities that have been occurring at the Site: For technical information, please review documents in the Information Repository.
INTRODUCTION
The purpose of this Fact Sheet is to notify all parties of concern that the U.S. Environmental Protection Agency is modifying a component of the Remedial Action for the Geigy Chemical Corporation Superfund Site through an Explanation of Significant Difference (ESD). Requirements of the original Remedial Action can be found in the August 27, 1992 Record of Decision. The necessity of this modification is based on information gathered during the data gathering component of the Remedial Design. This Explanation of Significant Difference adds a requirement for installation and periodic sampljng of monitoring wells downgradient of the Geigy facility:r;'
'i . . The requirement for this Explanation of Significant
Difference is specified in Section 117© of the Comprehensive Environmental Response, Compensation, and Liability Act and Section 00C.43C(c)(2)(l) of the National Oil anci HazarLous Substances Pollution Contingency Plan. A copy of this Explanation of Significant Difference has been added to the Geigy Chemical Corporation Supertund Site Administrative Record and Information Repository. The Administrative Record\lnformation Repository can be found in the Aberdeen Town Hall and in EPA's, Region IV Records Center. The public is encouraged to review both the Administrative Record and the Information Repository during normal working hours.
BACKGROUND INFORMATION
The Geigy Site is approximately one-acre in size, and is located just east of the corporate city limits of Aberdeen, North Carolina on Highway 211 in southeastern Moore County. The Site operated as a pesticide blending and formulation facility by various operators from approximately 1947 to 1967, and by retail distributors of agricultural chemicals from 1968 to 1989. The pesticides 'DDT, toxaphene, and BHC were received in bulk at the Site, blended with clay and other inert materials, repackaged, and sold. Pesticides were not manufactured at the Site, but were formulated by dry mixing into a product suitable for local consumer use.
STATUS OF REMEDIAL DESIGN (RD)
REMEDIAL ACTION
AND
The RD was initiated on July 15, 1993, and approved by EPA in March 1996.
Remedial Action (RA) activities started in September 1996. The RA included: (1) removal of the remaining concrete foundations and the disposal of 2,460 tons of debris to a Subtitle D landfill; (2) disposal of 4,475 tons of contaminated soils to a Subtitle C landfill; (3) installation of four extraction wells in the surficial aquifer and three extraction wells in the Upper Black Creek aquifer in the vicinity of the facility property; (4) construction of a groundwater treatment facility that includes an equalization tank and two series of activated carbon canisters; (5) construction of an infiltration gallery (the 1992 ROD gave an option for discharge of either an infiltration gallery or the local POTW) for discharge of treated groundwater; and (6) installation of six additional monitoring wells and three additional piezometers. The groundwater extraction and treatment system began operating in January 1997. The Site soils have been remediated; the surface of the Site has been restorated. It currently is covered with rye grass, wild flowers, and pine trees.
RATIONALE FOR ESD
The remedy as stated in the Record of Decision (ROD) has been implemented; the soils have been remediated and the groundwater near the facility is being treated in accordance with the ROD. However, the ROD required additional sampling in the second uppermost aquifer to determine the extent of the pesticide contamination and to determine if the TCE was site-related. This sampling was completed and the extent of the pesticide-contaminated
groundwater plume was determined. It was also determined that the TCE was not site-related.
A Downgradient Groundwater Remedial Action Work Plan was finalized in November 1997. This work plan details the results of the pre-RD sampling and provides extensive analysis of the results of this sampling activity. The results of this analysis indicates that periodic monitoring·
ttrtiltli}~t ""it, ~}ii~
I \[)]\~{
-,
•·
i]: .. ,.,v:;!&,':tJ'r:.:: \v:'
. u,.-,-__,,-,r,: ' .,. ~,.,.•,;;,-,-, 1 ~ l~ ~MW-MD•
Upper Black Creek Groundwater Plwne
CIDCIY Ct€liilCAl c~ ,m Wl!Pff'! lf211TH C..UUH pg
,, ., __ ··, . ., ' * . .. . .. ·~J:i~r:: ·? ·.. +rt..,:.,..,; •. ~ ... ·:
-• -
ICAU .. l'ln
IC4U.,.UU:1
-:-------------------'----------------,-------------,,--
1.,: e _.
. .:1 (j <>
··: g
Lower Black. Creek Groundwater Plume
O(IOV ~i.c.u,_ COIV'OIVJ'-,JII lrQ en•nPHN tt9'!1t1 fMR! .. ,
. ~-..
:--:-/jt ·.;
.... . , ..
:'/){.·::._
c}J'f~'.{~r,
~-...c~
···--· ·····
.. ,
1: ·:.•
·.·:,-·,_ . . ,:,
if'it1'.0( .~ :.,. ·; /
;Ilt~i1'.fu!iMt., i•
: ,fat~Ii._.:_•.:.:_i.:.•_;·.·:.i .. :.i .. ·i_• .. :•···•··•.:·_,:·•·:·.·:.·.·•:. -,.~/~/+ ~:.:: g 1
-', ~-, ••••~~•~.•.J•-.••·•a~ ~~_'::•,, ... • ... .,.
ICAU .. -.a
•f
of the downgradient portion of ~lume along with
periodic monitoring of the surfac-ater bodies would
address this groundwater contamination. This
determination was based on the following:
There are no receptors of untreated groundwater in the
downgradient area. Currently, there is one private well
user in this area. All other residences and businesses are
connected to the city water system. The private well has
been ·sampled and the water is contaminated with
pesticides. However, the Potentially Responsible Parties
(PRPs) have installed a carbon filter on the well, and
conducts periodic monitoring to ensure the proper
operation and maintenance.
The City of Aberdeen, by letter dated April 1997 informed ·
EPA that the City would not install any .municipal water
supply wells in this downgradient area.
Groundwater discharge to surface waters limits the further
migration of the plume. Groundwater flow directions have
been identified to verify that the groundwater pesticide
contamination plume is contained by the following creeks:
McFarland's Branch, Aberdeen Creek, Ray's Mill Creek,
and Trough Branch.
Pesti'e concentrations in surface waters do not
curreni(v pose a risk to human health or wildlife. The risk
assessment for McFarland's.Branch was updated based
on the new sampling results and indicates that the risk
associated with the downgradient plume is well below
EPA's acceptai:lle risk range.
Groundwater modeling has shown that the concentrations
of pesticides in this downgradient area will decrease in a
time frame comparable to a pump-and-treat system. A
groundwater flow model was used . to · simulate the
performance of six extraction wells in the downgradient
plume area. The model was also used to estimate the
extent and longevity of the groundwater plume under
naturally-occurring conditions. The results of this
modeling show that the plume would be remediated in 19
years under pump-and-treat conditions and would be
remediated in 25 years under natural conditions.
Additional Work
The groundwater plume not currently covered by the
extraction and _monitoring system will be monitored and
this monitoring, as well as other activities will be
incorporated as part of the overall site remedy. The
additional remedial action activities are detailed in the
Downgradient Groundwater Remedial Action Workplan·
and will be conducted in addition to the current facility
property groundwater !!Xtraction and treatment system.
They are as follows:.
Periodic measurement of water-levels will be conducted
to verify that groundwater flow patterns do not change
over time.
Periodic groundwater monitoring of select existing and
. proposed monitoring wells and piezometers. Monitoring
locations and frequencies will be reevaluated every year
for the first five years and every five years thereafter.
Periodic surface water sampling and stream sediment
sampling will be conducted in McFarland's Branch,
Aberdeen Creek, Ray's Mill Creek and Trough Branch.
Municipal Water Supply Well Number 2 of the Town of
Aberdeen's water supply system will be monitored to
ensure that the well is not adversely affected by Site
contaminants. The one residential well currently in this
area will continue to be supplied with a granular activated
carbon filter and will be monitored to ensure that the
treated water meets Federal and State drinking water
standards.
Periodic remedy reviews will be conducted to evaluate the
effectiveness of the remedial action.
AFFIRMATION STATUTORY DETERMINATIONS
EPA has considered the new information that has been
developed and the addition made to the selected remedy
and bel!e~•es that the rem~dy selected in. the ROD
remains protective of human health and the environment,
complies with Federal and State requirements that are
applicable or relevant and appropriate to this remedial
action, and is cost-effective. In addition, the remedy
utilizes permanent solutions and alternative treatment
technologies to the maximum extent practicable at this
Site.
PUBLIC COMMENT PERIOD
A 30-day public comment period has been
provided in order to give the public the
opportunity to comment on the proposed
action of this ESD. The comment period
begins on November 13 and extends to
midnight December 13. Please mail your
· comments to Giezelle Bennett, Project
Manaaer at the address featured below.
;
r
:r • ,. ·, t ,,. ' • FOR MORE INFORMATION/ . . , , ,
If you need more i~form_:"_,_;i,:•<_~$u1,s notice or status :;
Site activities, please caj 7ollowing: :.fr • cr;;.-i;· . . ,;Jf,l~
Giezelle Bennett, Remedial Project Manager
or Diane Barrett, Community Relations
U.S. Environmental Protection Agency
61 Forsyth Street, SW, 11th Floor
Atlanta, GA 30303-3014
Phone: [phone], ext. 28820 or 28830
1~~o~M~r1~N ~E{flT?~r ·,,, •• , . 11: , ,\,: : :: ..
Documents developed during the Superfund investigation
of the Geigy Chemical Corporation Site are housed in:
Aberdeen Town Hall
115 North Poplar Street
Aberdeen, NC 28315
Phone: [phone]
Monday -Friday -8:00 AM -5:00PM
. .. --. ·-. ----. -••" -, ----,---~. U.S. OFFICIAL~ ~:AH. n .... .t" , _, ·-U.S. Environmental Protection Agency North Site Management Branch '?' ;, PEN~LfV * ~ i FOR 00.32 61 Forsyth Street, SW Diane Barrett, Community Relations cd8~ct.i'97 PRIVATE * IJSCS300
Region 4 Atlanta, Georgia 30303 Giezelle Bennett, Remedial Projeci~nager * G " u ~E ~~~
Official Business
Penalty for Private use $300
-,····----
RANDY MCELVEEN ----------. SUPERFUND SECT ;0 ~ROJEC T MANAGER -------._
' NOR TH CAROL I NA DEP
HEALTH AND NATUR;c ~F ENVIRONMENT, P.O. BOX 27687 ESOURCES
RALEIGH
NC 27611-7687
, J II 111 ,,11,,,lll,,,l,li,;\,,1,l,,,11,,1,1,11111,111 11111 111 1 111
,
/1
• D~+-t--• ta~
EXPLANATION OF SIGNIFICANT DIFFERENCES
TO THE REMEDIAL ACTION
GEIGY CHEMICAL CORPORATION SITE .(:::=•=)· ABERDEEN MOORE COUN[Y Aiif'
Prepared by
U.S. Environmental Protection Agency
Region IV
Atlanta, Georgia
. October, 1997
TABLE OF CONTENTS
SECTION
Introduction 1.0
2.0 Site Location and Description
3.0
4.0
5.0
6.0
7.0
8.0
Site History
Record of Decision
Status of Remedial Design
Rationale for ESD
6.1 Sampling Results
6.2 Analysis of Sampling Results
6.3 Additional Work Required
Statutory Determinations
Public Notification
Figure 1
Figure st£> . Mod~l!ttjila$$011s for Natural Conditions Scenario
Geigy Chemical Corporation Site
Explanation of Significant Differences
October 1997
PAGE
1
12
4
6
7
9
10
•
EXPLANATION OF SIGNIFICANT DIFFERENCES
TO THE REMEDIAL ACTION
GEIGY CHEMICAL CORPORATION SITE
ABERDEEN, MOORE COUNTY, NORTH CAROLINA
1.0 INTRODUCTION • ~
This Explanation of Significant Differences (7§,PJ'was pr~p~I~litirit.~e Geigy div
Chemical Corporation Superfund Site ("Site"). ThEJ]Qtlrpose 9b!Jiis E~Ji!§t1£bQ,ocurpgnt
that the_ Environ_mental Protection Agency (EP_A_ or1,/11; Age'h¢1Y is ~ddlnij:i!i,fjfj~,jjlV
monitoring requirements to the Record of Dec1s1or'jj{ffl@,Q);Jor the Site. 'WJMMFFV . \tftiwmg;;81~.. ·--❖,:,~~~=-·-y
EPA previously issued the Geigy ROD on Aµgjll_ij{l@;el/,f);@92. The original
requirements and goals of the August 1992 ROD,,?,1e riffflr~ti§)liR,Section 4 below.
The necessity of this ESD is based on information;genera.l§Jffixfunng,the development of ~:io':''"' Remedial Desigo (RD). Th~~d io Sectioo 6
This ESD is issued pursuant 1f!ifSectiol);!,1 ?(bf;lfi!Uf]Eomprehensive
Environmental Response, Comp1J;l§Jtion aqfliabilit}jfAEf'{CERCLA), 42 U.S.C Section
961 ?(c), and the NaUonal Oil a,~[;1t1.azar~:s?f Subst$p~es Pollution Contingency Plan
(NCP), 40 CFR Section 300.4?&{c)(2)(1)¥i!i copy q{Jh1s ESD will be added to the Site
Administrative Record ang,to;tlife lnfbrrnlt[9n,figt@;itory, both of which can be found in
the Abersifllr:rown H<J!!;fil!lnii~PA's Rt!g!!iiifllR~cords Center. The public is
encouraga\111\ttiir~view'&lllJfiitlie/,AdministfaWie Record and the Information Repository
::iog~PTION
A;ffhe Geigy Sitel$11QpJt€d just east of the corporate city limits of Aberdeen, North
;:···•····'· ······•-·.· ❖.·,············· C~g!fha on Highway ijif'ih southeastern Moore County. The Site is jlfi approximately
,r.{.., o.@:~f~cre parcel loca1@P on the Aberdeen and Rockfish Railroad right-of-way. It is in
t!)gifi;rrm of an elongffed triangle between Highway 211 and the railroad, with the
t1]gffiy.!§cy and ra[li;gp'ti intersecting at the apex of the triangle. ~f f@r.i~'.ili!~jjj~:~:~~~~it@~F:f::::n:f f ~~pr·.
''tl!MMil!lieSife soils have been remediated; the surface of the Site has been
resto"il\'.fgcf. It currently is covered with rye grass, wild flowers, and pine trees.
Geigy Chemical Corporation Site
Explanation of Significant Differences
October 1997
• \
3.0 SITE HISTORY
. The Site was operated as a pesticide blending and formulation facility by various
operators from approximately 1947 to 1967 and by retail distributors of agricultural
chemicals from 1968 to 1989. The pesticides DDT, toxaphene, and BHC were
received in bulk at the Site, blended with clay and other inert materials, repackaged,
and sold. Pesticides were not manufactured at the Site, but were Jormula!g~'by dry
·•·~ ,S·.·-·•w mixing into a product suitable for local consumer use. Spills occiitted gµj'lhg the
normal formulation activities. A;S;t ,4![!!!!!~"--pi,
Soil removal actions were conducted in 198~/Jrid 1991. ,dpil;llllrnlit&,1989, AW
visual area~ of pesticide contami_nation were remolld and t2,,w~ste'§igJi911tt,ar@tP'
landfill in Pinewood, South Carolina. A total of 462Hons ot4l!aterial wererremovea,and :::,:,:::;,:,,.::,,:,::-,, ,1.,,,:,v ·-·-:,:::,:,,,:,:,:,,::,:,:,,,,::,,,,,,.,,,,,,,.
disposed. A second removal action was conducteq!j'i[J1(~~;1-Approximat~lyi284i tons
of soils and debris were removed. Of this, 505 tonihdl'/soiistwere transported to a h•······•r·········;;-· ,, ·
Texas facility for incineration. The remainder was,.dlspqseqfat:;a landfill in Louisiana.
4.0 RECORD OF DECISION Ai~~
The _ROD was s_igned on Au_g~-t~?. 1 ~j,':"aij,~i~lltt'lis groundwater an~ soil
contamination at t_he Site. The m~JjfJt:omp~lJ?hts of\~,1ietected remedy, as depicted
in the 1992 ROD include: Af(r/f!!lf · 4i'f ,,
• Extraction of groun_~w1tff ac1os11J~~---Si!:4iglthe upper aquifer _(surficial) and the
sec9Jil_p uppermosJ;i)Qli!!fer (Uppgr;f?lal:!Rt{;reek) that 1s contaminated above ,:.❖:.:.;.:,·,,_ /.:c❖.,..:-:-:❖.•:·.•.l•:•:<< ~--❖:·:-:,:-:-:❖:•:-:-:-:-:-:-::;•:-:.;.:,:-:u
•
•
Maximum ContaininanULevels dt\tne@Nohh Carolina Groundwater Standards ~,:dw,tec ,ia ca<boa adsmprtioo; •
Disoharge imtteatgi;i;groundwater to the local POTW or an infiltration gallery .
,:::1:f!J
4 \\i@iifiliifj~~~ijr,
• AifVContinued ana1;r~ff.fhonitoring for contaminants in groundwater.
~llfl]l;t ~~:f~:i;tion,,~l~J,,~e,r warehouse foundation; disposal at a municipal or secure
~~t@I:IJ~@~~1:t:::.< ,:. g::fJ11~JF
•fil&M;Ex&aM'&tlbn of the top foot of on-site soils contaminated above the performance
~,fr,t$tarid~rds;
• TCLP testing of the stockpile of contaminated soil to determine final disposition;
Geigy Chemical Corporation Site
Explanation of Significant Differences
October 1997 2
•
• Off-site incineration of contaminated soils that fail the TCLP test;
• Off-site disposal in an approved. hazardous waste landfill of contaminated soils
that pass the TCLP test;
• Backfilling, grading and revegetation of excavated area; ,,
• .❖. J!!ffiY~
• Additional sampling and analyses of the second uppermo~;tjgquifgfJfo determine
the extent of pesticide contamination, and to de~~![mine iJj~!J~Ui!!PH1oroethene
5.0 ::A:~:,::;::,.::~~;:::::::dD R~
7
The RD was initiated on July 15, 1993. The"'i!Jeij1grrI0Uhe remediation activities
identified in the ROD, including the additional samgj(flg!il~ifie@.n completed. The RD
was approved by EPA in March 1996. «ijf 'it,;i;4l]#iiih,
•
•
•
•
•
.. ,,d:di:};J;+❖• ,~<t:~~fiJ~;;;~;.;;J~;:}
Remedial action (RA) activities staq~lj~i,iq~l!:/.mber 19~l?)!W'The RA included:
:,e:;;~;~ I~ ;~,~~=;~:s,-r.w:sposal of 2,460 toos
Disposal of 4,475 tons of[¢&fitaminfilfud soils.if a Subtitle C landfill; a ~;-::S:::,~~":,e;h~"~:~~,:·o:::~;'."
Con~1l!@!l9!hPf a gto,qqg~§[ treatment facility that includes an equalization
tank ,~,:~llllli?t:, of'~~Jii:IJP carbon canisters;
c,99sttuctio'ffl~~!1Pli!PiIItrati6n gallery (the 1992 ROD gave an option for
,,tfischarge of ei\jJiii,}rtfiltration gallery or the local POTW) for discharge of
11;itreated ground'-%fJf~JVand i?~? Hi ,,.
•Alii!( Installation otJ'f additional monitoring wells and three additional piezometers.
,111111111:nEh§! gr.qvntf!er extraction and treatment system began operating in January
i@gzI!llnis1§pre'1, the extent of the groundwater plumes in the surficial aquifer and the
U~pe'~!Siatk''creek aquifer as identified in the 1992 ROD, along with the seven
extraction wells are shown.
Geigy Chemical Corporation Site
Explanation of Significant Differences
October I 997 3
•
<£JZlll
Mir-~ DtlSTWC IKIWtr#tC .ct
P9'-IS'♦ DtlS1lltG UrRACflON EL
£]11S1W(l llQL l'ONT "1Uall£1ER
""" £,XTRAC110N ¥1L l'Ota I/Ml
•
f«HWAr 211
FIGURE 1
Groundwater Plume based on 1992 Information
and Current Remediation System
fl
" //
/J ,,
" " " 1RCA111EN1Jtp,DIW7
I
It
" " RAICD ~,or _,,_,.,.,
WW-14D •
NORTH
t
WW-15D •
EXTRACnav ANO
T1?£ATll£NT SYSTEU
SITE LAYOUT
•
6.0 RATIONALE FOR ESD
There are three types of post-ROD changes. Depending on the extent or scope
of the modification being considered, the post-ROD change is either (1) non-significant
or minor; (2) significant; or (3) fundamental. A different documentation procedure is
associated with each type. For non-significant or minor changes, these chqnges are
documented by recording the change in the post-decision document file. Jlii~
dissemination of a fact sheet to the public is optional. For signif~jfil! '2tt~Ifes to a
ROD or RA, these changes should be documented 1n 2n.,,ESD,1?Ril;t~S~{:ed by CERCLA
and the NCP. Fundamental changes to the remedy s~qpld be dd¢.U!lilf!!';JtE?,d in a ROD ,,.
ame
nd
;;:t~as determined that the changes and t(t:on,§fPf!~:Jf!!~11l,l1fffe/;fpI;f
constitute a significant, not fundamental change tdJffig;gijfgfnal scope of tffe'.!r;emedy
selected in the ROD. Therefore, an ESD is approp'ilatftto!lilocument these changes.
6.1 SampllngRos•lts . ~
The remedy as stated in the ROD l'\g@.!!®'.&ffli!mpJementedjfff,fe soils have been
remediated and the groundwater near tg,1f1l:81Fitwffi12i1f!g,,,trea1icfin accordance with
the ROD. However, as stated in Secv,ff 4 of tp'jsrlq,lffil!l'ltffene ROD required
additional sampling i~ the second,~,~rm?s}fquifer'ifJl~i§'rmine the ext~nt of the
pest1c1de contamination and to de.humine 1iJthe TCE was site-related. This sampling £;-:-:-:-:-:~~❖=~❖ ;{1-··=·=>" ff.;-:.,.
was completed and the extent4ifj}tie _pe~~&de-con!,liliinated groundwater plume was
;;~~;-~~t£~;~f :~~~:;:~~~;!~~:·
was also determm$/!Mhat the•'fiCE1was not site-related.
~T,Resolts
.,£7A Downgradienff{llt,qfihdwater Remedial Action Work Plan was finalized in
Ogpper 1997. This \V'.grkplan details the results of the pre-RD sampling and provides
EJ.~\~psive analysis qJ(the results of this sampling activity. The results of this analysis
i_l;jgl'/g~\es that periqf;fib monitoring of the downgradient portion of the plume along with
~~t/~gi9;,'}!9D~l()OV~f of the surface water bodies would address this groundwater
cqf!t{!rtllfil~!i![tliThis determination was based on the following: · ·-=~:Prnf:f mt~twt:~====·/
• There are no receptors of untreated groundwater in the downgradient area .
Currently, there is one private well user in this area. All other residences and
Geigy Chemical Corporation Site
Explanation of Significant Differences
October I 997 5
N
1 Legend
-10-
WoadodArn
0 P,e,.....,..,1Nul
Ui>s-,-tDwet Bla,ctC,..,t Aquilet
... :;/
_:_\.;:;L· ... ~ ... ,• --::. __ _
S11•-s1..-1 G-•
Monolot~\IVwll \.lpp<,O l!Jacl< C.Nt Aq,..u.,
f'leu,..,~ .. ,
~pH 111:iclt C,ut A,iull.,
Total BHC Coocamation ~/l tDnhed where interred)
D
;, '."•
'1-•"' r
\~
-.. ~ ..... . . c:::;::·~:.<<f?il/(:iJ_ ·--~-
';.~-
• ,:.,,,,,0,:! ,, •' MW~•o0 , w,~o ·,. )':, •.,
•,t-~~ '•'" •~1.'.~11 :tff lb~.&,:~\: .. ~~ ];j"·)FJ,:;;:-:-1
•
0
,-·;'. .. Mw -4D \:~::J;:14o~ • , •• , ,f -~ ;, 1-.. .,,. ,,. , ,. , • j,!/}W 14D ft1 r_ 1, _
' ~·1: -,~}
,oo D ,oo ,.oo
SCAU IN FEET
'"
SCALE IN Mil.ES
FIGURE 2
Rust Environment & Infrastructure Upper Black Creek Groundwater Plume
N
~
[:::..:::
~
/V
/1/
/V
<> ...
Legend
...,.
Swamp
lluol<l~,u
Pa~d fl•ul<la
Uni>•.,.dl-load•
-..A.r ...
l\alro.i~
Sltuaon
~·~ M<>n;UM"'9W.,Wfi.,z.,....,_
lo,,,,,n<>IAt.rdo,M_.,.,we■
~
0
" ID
Town at Abllntoan Muriiclpll Wlil ,..........,
P;o,_..,..,,,,,..,
lip--U,w., Black c, .. ~ Aqlliler
Su•-SlDltG-•
-10-lolal BHC Conccntr•tion f'Oll !Dashed whO!le inlencd)
0
Rust Environment IL. Infrastructure
,. ,, " '''.\
~ ...... ,,
~ .. --... ,,,~"":,,:~:?--/· . -~.:::,,. •
800 0 '"" """
SCALE IN FEET
"
SCALE IN MILES
FIGURE 3
Lower Black Creek Groundwater Plume
0 •
businesses are connected to the city water system. The private well has been
sampled and the water is contaminated with pesticides. However, the Potentially
Responsible Parties (PRPs) have installed a carbon filter on the well, and
conducts periodic monitoring to ensure the proper operation and maintenance.
• The City of Aberdeen by letter dated April 1997, informed EPA that the City
would not install any municipal water supply wells in this downgradie'ht area,
. . . . if~[[!tt:,. ,6[~¢/)f/
• Groundwater discharge to surface waters limits the furthemr111gtat1on of the " :· _,::,;.···:···o···:· .•.• ·,.··,;.. plume, Groundwater flow directions have beerildentifiediJO:lv§rlfy .. that the .. . .:~=~::::::::::::>•>" . :y:-:=:::::~:::,,;:;:~:::::::::: .. ::~;.~.. . )""'~
groundwater pesticide contamination plume Ji;cbntaineg1gyltfj!'i][ti!!§»:ing cree,1$fi'
McFarland's Branch, Aberdeen Creek, Ray'.$jfv1ill CreeK;Jand Tlo.tlgfiller:qnc_;;lnW''
_ mlt~:G":l(.;,,j\, \J\1111,1~:*w
• Pesticide concentrations in surface waters a~Inl;lt;(igrrently pose a rlsRHcP6uman
health or wildlife, The risk assessment~sltJp~l~~!.q?sed on the new sampling
results and indicates that the risk assoc1atechwitllilllierdowngradient plume is well ·'··•V. v,;:: ... , ......... , ........ . below EPA's acceptable risk range of 10·4·to' 1 o-6 -ct,w;;,,,0s,•1·~
.-:-.,H.@~y. • ~~-:=:~::tj,:~:~~;::;:;;;;1~;:;:t2:~,-=❖❖
• Groundwater modeling has shown Ji:l1§~1!1g9,7otrati8ijlpt'pesticides in this
downgradient area will decrease .ioar11meararoewompa(a6le to a pump-and-treat
system, A groundwater flow IT}gdel wa~;g§§~lt§!~!lm!~t~ the performance of six
extraction wells in the down9cfoient pJgme arej!/~!Jrr!5e model was also used to
estimate the extent and l99ggvity of,t!je groung:)vater plume under naturally-
occurring conditi_ons. _T,;~j;ret~lts;gfthis moR,fllng ~ show5t_h_at the ~lume
would be remed1ated im},9 year~J!i!Qfler pyf!lp-and-treat cond1t1ons (Figure 4) ❖ .w.w· / •.·.·•·.•.••·•·.❖•••••• .•:·,,.•.❖.•./ -~
and )MOUid be rem¢.!:li?J$°d in 25 y(l)'J.lfiill!!Qger natural conditions (Figure 5).
· kS::., pl"me oot omeotly co,e,ed by the
extraction and!mdnitptifig;.systehi)Wnl be monitored and this monitoring, as well as other 4..❖·✓-.''u_,··.··':: .✓-c::·::·· <:;i, activities,WiWbe incbiipbiatedas part of the overall site remedy. The additional
remedi,faction activ'ft!ift~l:iiitietailed in the Downgradient Groundwater Remedial _,/'-'>:'9-~:-;~::::::::::;:::::,:;:::,::::::~F •
ActiQ!}'Workplan and '<Vllh\:lfi'conducted in addition to the current facility property /',:::f.x,; . • ,.,,,,,.;:: ,,~, groundwater extract1on;and treatment system. They are as follows:
U:::::::~::t:,:::,~:::::::,d"cied to ,erity that
<t%gi'btitidwater flow patterns do not change over time. In addition, the natural
processes of dispersion, adsorption, and degradation will be evaluated by
updating the groundwater model with monitoring well data as it is collected to
Geigy Chemical Corporation Site
Explanation of Significant Differences
October 1997 8
----------------"·~~~lf£l_' :~ >. ~:. ~ 1Le
Ro:dttctlon ii, M11n olG■-flflC 11'\lh ~
Cannplual l'u"'Pfflll C.oudlll""'
Nn Ad,-pilc>a ■ml No lkg111dti1lnn
Lower IIIKk C:n-rkA!)lllfrt
Pumping Rate w,n !9pml
,W-~ ,oo
PW-2l " PW-3L " PW-4L " PW-5l " PW-6L " PW-7L __ ,_,_
Toi;,! Exu■ctt<>n R,ue "' 245 gpm
Ta1al Injection Rall! • 100 gpm OW-IU
N
legend
CT::] fbnd
~=J s-
~ 8uil<lln9
/'v' Pa119dRa-,19
IM,odedA1-■
.,...,.. --· /'vi Str•..,,
0 US EPA
ManilDfing -•--.
0
-_,,olAt,e..-.,,,~WBI
-...rA.bt'odem~-~-· fw?Oln•l•ff<lnl ~ Black O.,,k """"'•
s1, • .,.s1..r10-
Mon11arlnQ We• i.-,m.etC-k ........ -,,_.._ __ .__, _____ .,..,
-~&..14.,e..--.
PUMPING COND/71ONS ,oo 0 800 '600
NO ADSORP77ON, NO DEGRADA71ON
Rust Environment IL Infrastructure
SCALE IN FEET
FIGURE 4
Modeling Results for Pwnp and Treat Scenario
GEIGY CHEMICAL CORPCIAATION SITE ABERDEEN. NORTH C.6.ROUNA
1Crd>1<1ioa b, ~i. .. gf Ganoma-PHC.,.i,b Tim, r...,_...i lklll<il} c_,
No Adsoqui<>11 and No 0.;n,<lolN>o
1 .. .,..,. Ul:oc~ Cnd; Aqulfrt
20
20
lime(Y,:ors)
N
Legend
[I'sJ l'Gnd
~' Duildio!,i
/'-./ r~ved floacl•
_,,,, __
./'V lldr-•
/V s11 .....
~ US EPA
MonilOoino;iwelllPI••-"''
"'
0
TownQIA"-nl••nMl.nlc:,pDIW•• /V O-QHC-....,.,.,agc,ai.Jnal0.701'11111'
bwnol""""'•"·"""""""'w.1 JAb--dl
l'otoron,a\o<Nul
Law-, Black C.Hk AQullo,
s ...... sU111G-
Mono,orin11WeG
UJ'WflBlacl<Cno•kAquilef --·-••qw--.. ----""1 .. -b-'/ EPA-ilog 6.M.96 -irlll.
PROPOSED REMEDY CONDITIONS
NO ADSORPTION, NO DEGRADATION
Rust Environment 8t Infrastructure
300 0 800 """
SCALE IN FEET 10-SEP-1997
FIGURE 5
Modeling Results for Natural Conditions Scenario
GEIGY CHEMICAL CORPORATION SITE NO
•
determine its effectiveness.
2. Groundwater Monitoring
3.
4.
5.
Periodic groundwater monitoring of select existing and proposed monitoring
wells and piezometers. Monitoring locations and frequencies will be reevaluated
every year for the first five years and every five years thereafter. Af!W"
Smface Wate, aod Stceam Sedtm,m MoaltM],;;, 1/irL
Periodic surface water sampling and stream,$gdiment sa,mjplln§l\W!lJIP~ :,/2f p -
conducted in McFarland's Branch, Aberdeecltltreek, ReiyJ§ Milil!g;t?$§kiilnd .,,:f."".
:::,hS~~~:h;cotectloav ~
Municipal Water Supply Well Number 2 ofihe Townlgift:Xffi~fdeen's water supply
system _will be moni_tored to ensure th.51:;l;filifi'IX~II is ndt{ll\l!f ply affected by Site
contaminants. Res1dent1al well proteet1oniWfllibe accomplished by well permit
:t~i~~t1ir;t~~~:::~~;~v~~:~~~~j,e~:~:;1111111i1iif:~;~~f :;1:~~ve gone
into s~rv1ce. The one res1de_21ia1 well ,¾yrrentlY1filtt~lS?rea will ~o_ntinue to be
supplied with a granular a,§!1Mated C?,(lijon filtertj:tnd will be monitored to ensure
.:f:•:•:•:•:•:•:•:•:•:,A -❖~;-•. ;(❖:<"?
that the treated water ll}§~}!FFed~~Vand St~\jfdrinking water standards.
7.0 "STATUTORYQE;T;EEIMINATIONS . .ltt ttitiHtHrr·· AIY Hff\@fV .4ll!il' EPA has consiqfrea the new information that has been developed and the
a,§~!tlon made to the,;~~lected remedy by this ESD and believes that the remedy
~~l'.iilt!=Jd in the RQgfffemains protective of human health and the environment, complies
lltti!nggg,ral snli!IState requirements that are applicable or relevant and appropriate to
it~lf~fil~mf~llicffon, and is cost-effective. In addition, the remedy utilizes permanent
soillitlons!ai'\'i'f alternative treatment technologies to the maximum extent practicable at
this Site.
Geigy Chemical Corporation Site
Explanation of Significant Differences
October 1997 11
• •
8.0 PUBLIC NOTIFICATION
In accordance with Section 11 ?(c) of CERCLA, EPA will publish a notice of the
ESD in the local newspaper, which describes the ESD and its availability for review.
An ESD Fact Sheet was_also prepared and mailed out to the persons on the Site
mailing list. J,._ 3.,, ~ ~ ~~ lA.M ~> fe---l,
r~-;,~s~~"~
.-:":. ::::, , , ¢~':-,' ,..,_ ,,.,..,.;,,'',,
Richard D. Green
Acting Director
Waste Management Division
Geigy Chemical Corporation Site
Explanation of Significant Differences
October 1997
I' /~_;_rr.-_~.t_1
._:_:.:•.:_[_r_-_: ... _.r_·~---[-,1_•-.:_~.: __ '. ___ :t_'-, .. :_.:.:_~~-f._;_r.,_I.:_I.::_•-_r.
1._-.:~.:_-.::1_r_;;'.!;;'.:
5
J_••_ll@:!;_4v ··:<L · ·
.. ---······;··
::::::::·:·:~;;;::::::,:,:::::::.:::::_ .. ··••tBW:tYt?:?~~-
12