United States
Environmental Protection
Agency
Office of
Emergency and
Remediai Response
EPAIROD/R05.881064
March 1988
3EPA
Superfund
Record of Decis~on:
Eau Claire M~Jnicipal Well, WI
u.s. Environmental Protection Agency
Region. III Information Resourc~
Center (3PM52) ,r
841 Chestnut Street T' :, .;~
Philadelphia, PA 1919~$iiffj
Hazardous Waste Collection
Information Resource Center
US EPA Region 3
Phnadelphla, PA 19107
EPA HepE1rt Collection
InformatiDn Resource Cente
US EPA Region 3
Phi!c~~elphiB1, PA 19107
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.50272. 101
REPORT DOCUMENTATION
PAGE
: 1. REPORT NO.
EPA/ROD/R05-88/064
! 2.
I 3. Recipient's Accession No.
_._-_._~_.
4. Title ana Subtitle
UPERFUND RECORD OF DECISION
au Claire Municipal Well Field, WI
~irs& Remedial ActIon
. 5. Report Date
k-93/3l/88
6.
----I
7. Author(s)
18. Performing OrganlZati~R;;;~~.'- .-
9. Performing Organization Name and Address
10. Project/Task/Work Unit No.
111'- C;ntractCC1' o~-Grant(~-
I
, 'Ci
--I
12. Sponsoring Organization Name and Address
.5. Environmental Protection
~Ul ~ Streec, s.~.
ash~ngton, D.C. 20460
I (G)
i
Agency
---. .
I 13. Type 01 Report & Period Covered
!
800/000
i 14.
-1
I
I
i
15. Supplementary Notes
16. Abstract (Limit: 200 wards)
!~e SOO-acre Eau ClaIre Municipal Well r1eld (ECMWF) sIte 1S located in northwp.stern
~au ClaIre County and southwestern ChIppewa County, WIsconsIn, at the ~onfluence or ch~
Eau Claire River and the Chippewa River. ECMWF supplies drinking water to approximately
57,600 residents and numerous commercial establishments in the city of Eau Claire and
ash1ngton Township. Ground water from five munic1pal wells 1n the north well.f1eld is
ontaminated with VOCs. The contamination at the SCMWF site has been characterized as
.two separate plumes with the estimated volume of contamination at Plume 1 and 2 of
1.9 x 108 ft3 and 2.6 x 108 ft3, respectively. The Chippewa River is. not
believed to be affected by this VOC contamination due t~ municipal well pumping which
prevents ground water discharge into the river. In March 1981, as part of the EPA
round Water Supply Survey, the Wisconsin Department of Natural Resources (WDNR) tested
t~e Eau Claire municipal Nater supply for ~OCs and did not detect 70es at levels of
immediate concern. Additional testing of the city's active productIon wells, in January
1982, reported VOC concentrations below health advisory levels. Concerned about the
future use of the water supply, additional testing in September 1982 and January 1983
as conducted to identify the source and extent or VOC contamination. Several
residentIal wells reported detectable levels of VOCs including, l,l-dichloroethene
(See Attached Sheet)
._-
17. Document Analysis a. Descriptors
ecord of Decision
Eau Claire Municipal Well Field, WI
First Remedial Action
Contaminated Media: gw
KeYb.S;;>.r.\tW~1~R.fn~~d Te~~~' TeE, 'lOC3
c. COSATI Field/Group
18. Availability Statement
~'security Class (This Report)
L- None
I ZOo Security Cia~s (This P35ite,
21. No. 01 Pages
42
. .--.----
. 22. ?nce
ne
(See ANSI-Z39.181
See instructions on Reverse
OPTIONAL FORM 272 (4-77\
(Formerly NTIS-351
Department of Comm~rc~
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PA/ROD/~05-88/064
Eau Clalre Munlcipa1 Well Fleld, WI
First Remedial Action
16.
ABSTRACT (continued)
. :oncentrJtions ~n ~xcess :f t~e ~DNR ~ealth advisory. The Eau Claire site was ~iven a
high Superfund NPL prlority by WDNR due to the nature of the toxlcity and perslsr.ence at
the contaminants and the large population affected. The primary contaminants of concern
affecting t~e ground water are VOCs and include: chloroform, DCE, dichloroethene, PCE,
~cz, 1nd ~ric~loroethane.
The selected remedial actlon for this site includes: ground water pump and :reatment
uSlng the existing air strlpper with discharge of created water to the municipal Nater
system and the untreated water to the Chippewa River; and provision of municipal water
to private well users within or near the area of ground water contamination. The
~stimar.ed capltal cost Eor this remedial action is ~1.214,200 with 3nnual 0&:: ~f
~396,700.
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.
DEClARATIOI
SITE MAlE All) lOCATION
Eau Claire Municipal Well Field
Eau Claire, Wisconsin
STATEJlEJfT OF BASIS AJII) PURPOSE
This decision document presents the selected remedial action for the Eau
Claire Municipal Well Field site developed in accordance with the
Comprehensive Environmental Response, Compensation, and Liability Act of
1980, as amendea by the Suoerrund ,i.menaments and ,
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-2-
This remedy involves groundwater restoration, therefore the remedy will not
result in hazardous substances remaining onsite above health-based levels.
,(31/g~
I
J.v-'l
i ----
/)
"
Date
~-.-~ tt( - ~~
Va das ". Adamkus
Regional Admlnistrator
U.S. EPA, Region V
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DECISION SUMMARY
Eau C~aire ~nicipal ~el1 Fi~ld Site
SITE NAME" lOCATION.. MD DESCRIPTION
1.
The City of tau Claire is located in northwestern Eau Claire County and
southwestern Chippewa County, Wisconsin, at the confluence of the Eau
Claire River and the Chippewa River. ihe Eau Claire Municipal Well Field
(ECMWF) site ;s located in the northwest corner or Eau Clair~ on :he east
bank of the Chippewa River (Figure 1). The municipal well field, a 500
acre site, supplies drinking water to approximately 57,600 residents and
numerous commercial establishments in the City of tau Claire and ~ashington
~ownship. The ECMWF is ail/idea ;n'!:o non:h and south sections ,.,ith nine
'Ne J 1 s deve loped; n the north 'He i 1 fi e j d and fi ve we 11 s deve 'j oped in the
south well field. All wells are set in the glacial outwash sand and gravel
aquifer. In addition, a number of private wells also draw from this sand
and gravel aquifer. The aquifer is hydraulically connected to the under-
lying sandstone aquifer, which is not used due to its low hydraulic
conauctivity.
Sroundwater from five municipal wells in the north ~'fel1 field is contami-
nated with volatile organic compounds (VOCs). The conLamination at the
ECMWF site has been characterized as two separate plumes. There is a plume
at the municipal well field (Plume 1) and another upgradient of the well
field (Plume 2). These plumes are shown in Figure 2.
Sources of natural recharge to the aquifers are local precipitation and
infiltration of flood waters along ri~er terraces. The Chippewa River is
not be11.eved to be affected by this contamination since pumping of the
municipal wells prevents discharge of groundwater into the river.
Land use in the vicinity of the well field consists of light industry east
of the airport and residential areas east and south of the well field.
o
II.
SHE HISTORY All) EJlFORCDEJIT ACTIVITIES
In March 1981, as part of the U.S. Environmental Protection Agency (U.S. -
EPA) Groundwater Supply Survey, the Wisconsin Department of Natural
Resources (WDNR) tested the Eau Claire municipal water supply for VOCs. The
following four organic compounds were identified in the municipal water
supply: 1.1-d1chloroethene, 1,1-dichloroethane, 1,1,1-trichloroethane, and
trichloroethene. The ~ONR informed the city that none of the compounds
were detected in the finished water at levels to be of immediate concern.
In light of the EPA groundwater survey, the WDNR district office conducted
additional testing in January 1982, of the city's active production wells.
The samples from all but one well reported VOC concentrations at low or
trace levels. Two of the wells sampled (Wells 11 and 15) exceeded
Wisconsin health advisories for potable water supplies for 1,1-dichloro-
ethene. However, due to the blending of clean water from the other wells,
the contamination in the finished water was below the health advisories.
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FIGU~E 1
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FIGUHE 2
EAU CLAIRE MUNICIPAL WELL FIELD
fO-
ana LM..... N
a
r
aaoo
~
LEGEND
...~,
t .\~ ., P 8 d
\.:..-.iJ Jum. OUII ery
- J_--- J.lunlclpa' W." Flah.1
Boundar V .
~
E.lllln" Air Shipp.,
.
A&Uv. ProlluCllon WaUl
~
W.II. Conn.CI.d 10
Air Slllpp~r '
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2
I
Concerned about the future use of the water supply, the City retained E.A.
Hickok and Associates in May. 1982 to conduct a hydrogeological study of
the well field to identify the quantity and quality of water expected for.
the next 20 years. In September 1982, the City requested that Hicxok and
Associates conduct additional hydrogeological testing to identify the
source and extent of vac contamination in the weil Field. In addition,
Strand Associates, Inc. was retained to evaluate various treatment
alternatives for the removal of vacs and options to improve iron and
manganese removal. Concurrently, the City also upgraded laboratory
equipment to provide capabilities for vac analyses for monitoring of
municipal and residential wells.
~ith the new laboratory equipment, the (ity jegan testing crivate
residential wells, in dadition to monitoring the municipai production
wells. Residential wells located on the north side of Eau Claire and in
the Town of Hallie. located immediately northeast of Eau Claire. were
sampled to gather background ;nformation to assist in defining the extent
and identifying potential sources of the vac contamination. Several
residential wells report2d detectaDle levels of 10C5. Figure J shows the
area served by the Eau Claire water distribution system and residences that
do not aDpear to be connected to the city ~ater system.
As a result of the residential well sampling. the City informed Mr. Donald
Hillman that samples collected from his well on January 12. 1983, indicated
a l,l-dichloroethene concentration in exc~ss of the WDNR healt~ advisory
level. The City advised Mr. Hillman not to use his water supply for
drinking. Mr. Hillman's well is approximately one mile upgradient of the
municipal well field in the path of contaminated groundwater fiow.
By spring of 1983, the WDNR had nominated the municipal well field as a
potential Superfund site. In September 1984. the Eau Claire Municipal Well
Field site was proposed for listing on the Superfund National Priorities
list (NPL). ihe site was listed as final on the NPL in September 1985.
The Eau Claire site was given a high priority by the WONR because it
affects a large population and because the contaminants have a high
toxicity and persist in the groundwater.
In May 1984. Strand Associates submitted their report on water treatability
for the City of Eau Claire and recommended a packed tower aeration system
for vac removal. A pilot air stripping column was constructed in the
Summer of 1984 to study the effectiveness of a packed tower. The
preliminary test results indicated that this pilot system successfully
removed vacs from the water supply.
In addition to monitoring the private residential and municipal production
wells, the WONR began to investigate the potential sources or groundwater
contamination in Eau Claire. In the Summer of 1984. WONR representatives
investigated vac handling by 22 commercial establishments through
inspecting the facilities and interviewing the owners. Of these. the WONR
identified nine that it determined were potential sources of contamination
based on operational information developed through the investigation.
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.~~~
D.
...~~~ N
o
LEGEND
- E"i.Ung W
~ tit Un..
-. P,opoud W
. .,., Lln. e
P" .'.n.loll
~.,. W .
O . I~ In PI
uno" II
P,'~.,. W
I .u. Wllh
oPium.. ,.In 2000 II
Iii
P,'v.,. W
.11. 0,.
2000 II F . ".1 ft..
'Om PI . n
"',,., un...
O,ound
I\!~~ waler Dlvld.
~')JiJI Plu",. 8
* uundHI..
R..ldene..
To or Siruel
po M.p UI. 0<1 USQS
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3
CERCLA related enforcement activities began at the site in 1984. A
ResDonsibl e "'!r'1:y Search '1fas conduc:ed ':0 i dent; fy pote~ti al sour'=2S \lr ':~e
groundwater contamination. Nine parties were identified as either having
current or ;Jast '/OC di sposa 1 prac..; ces ..-ili Co may ilave contri buted to
groundwater contamination. In June 1985., Request for Infonnati onl etters
from the U.S. E?A ~ere sent to the parties. No potentially resDonsible
par~ies (PRP! ~ere iaenti fied. However, as a result of the RI/FS, one ?RP
is being sent a notice letter (see Attachment A).
On October 24, 1984, a CERCLA Trust Fund allocation was made to the site
'Jna s. ,:.emeai a t :,wes,,~ gat~ uniF,=asi bi ~ j '<.y .:; tuay \ ~I /FS) ...os : nl"C"! ,jtea - c.\,
~r~j~.771iii~r:' J~yar':ge4Jiug1G 2'l<:.i~a'c~::n ...as ';~Trpi~\.2a ~ii Apr~i ~3a5, ca
summarize available geologic and hydrogeologic data in order to identify
infonnation gaps and to provide a basis to focus work efforts during the
RI. The evaluation developed a general bedrock topography map using
drilling logs, reinterpreted seismic refraction data, and utility
excav~~ions. :ne ~relim;nary r~~ort also stared :~a: ~raundwat~~
contamination up ~octle time the report was issued had generally been
confined :0 monit.Jring wells screened in the out~ash aquifer tha~ ~as
~.JcJtetJ "i ::1~~ ~h1: ,;e'::rQc~ .:~annel.
In April 1985, a Focused Feasibility Study (FFS) was conducted to evaluate
d limited number of Initial Remedial Measures (IRMs) and to identify a
cost-effective IRM for implementation. The primary objective of th~ TRM
was to protect public health by providing a reliable supply of safe potable
water to those consumers dependent on, the Eau Claire Municipal '..ell Field,
prior to completion of th~ ccmprenens;v~ .RI/rs~ '
<:.
In the June 10, 1985 Record of Decision, the U.S. EPA Region V
Administrator determined that construction of an air stripper was a cost-
~ifec:~ve i~i~~ai remedial ~easure t~at ~ouja provide aaequate protection
of public health, welfare, and the environment until the completion of the
RI/FS and selection of a final clean-up remedy.
Jesign JT :he ai, 5~rip?er ~as .:cm?1e~2~ in ;~bruarJ :986. CJns~iuction OT
the air stripper was initiated in July 1986 under the management of the
U.S. Army Corps of Engineers (USACOE). St. Paul, Minnesota district. Air
stripper construction was completed in June 1987 and it was placed on-line
in August 1987.
Concurrent witn the air stripper design and construction, U.S. EPA
continued RIfFS activities.
.." ..
JoJ..J. .
c~)t~~
;~~-;:t:~S
The Superfund activities at the ECMWF site have been followed closely and
consistently by the local press. However, historically there has been very
little public interest from the community.
As required by Section 113 (k)(2)(i-v) of CERCLA as amended by SARA, a
public comment period for the RIfFS and Proposed Plan began on March 5.
1988. Copies of the RI r~port, the FS report, and Proposed Plan ~ere made
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4
available to the community on this- date. Two locations served as
repositories for these reports, with the administrative record being
located in the L.E. Phillips Memorial Library repository in Eau Claire.
u.s. EPA issued a press release containing the Proposed Plan prior to
commencing the comment period.
The public comment period ended on March 25, 1988.
the attached responsiveness summary.
Public comments are in
IV.
SCOPE Of RESPONS£ ACTION
This remedy r~presents the final remedial action fnr the EC~WF site. In
January 1985, ~he RI was initiated to define the nature and extent of
contamination and to characterize the potential threats to public health
and the environment. RI field activities were performed in three phases,
beginning in November 1985 and ending in October 1987. The results of the
RI are discussed below.
'f.
SITE CHARACTERISTICS
Groundwater
To define the nature and extent of groundwater contamination at the ECMWF
site, monitoring wells were installed in the water table outwash aquifer,
with the exception of two wells that were installed in the sandstone
fonnat; on.
Groundwater samples collected during- the RI.-indicate the presence of low
levels of volatile organic compounds in the water table aquifer. These- .
samples also indicate the existence of two separate plumes of VQCs.
One plume (Plume 1) is located west of the airport and extends into the
municipal well field, while the other plume (Plume 2) is located east of
the airport and extends to National Presto Industries (Figure 4).
Currently there are five wells in the municipal well field contam;nat~d
with VQCs. Surrmaries of the volatile organic compounds found in Plume 1
and Plume 2 are in Tables 1-A, 1-8, and I-C.
From the samples collected during the RI, the VOCs detected most frequently
and with the highest concentration in both plumes are:
Contaminant
Concentration Range (ug/L)
1,1,1-Trichloroethane
Trichloroethene
1,1-Dichloroethane
1,1-Dichloroethene
Tetrachloroethene
Chlorofonn
0.03-155
0.02-13
0.01-5
0.01-4
0.02-3
0.03-1.75
The extent of the two contaminant plumes is shown in Figure 4. Plume 1 has
an area of about 1.5 x 107 square feet. The saturated thickness of the
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T.ala I-A
Su..irv Q~ Ground.it., SAS Valitill Orginic~~iti
Eil Chi n !laIF -
-
Phsi 1 Phall 2 Tahl
I ----------------------- ---------------- -----------------------
I
P~RAI!ETE.; I ~r1!t1ulncv R...,Qm(ou) r:,!!~ulnq R~nq~(laz) ?:'t't1ul2ncy ~M~\'J (!lax)
I
--------------------------------------------------------------------------------
Trins-l,2-dicnlaro.tnln. 2J.-4 O.02~.27 0/47 2"1 0.02-<1.27
1,1-dicnlaro.tbinl 16144 O.04-~.6 2~/47 0.01-5.0 41/91 O.OI-'.i
, Cil-l,2-dicnloraltnlnl 7/44 0.03~.2' 16/47 0.02-2.1 23/91 0.02-2.1
!.l-~ichlofolthlna 17/ ~4 O.02-~.3 20/47 O.al-~.7 :7/fll O.OI-~.:!
1,1,1-~ric~loro.thano ;0/44 J.06~2.0 !1J/47 !J.O:H~~.O je/;! ~.03-i55.0
Tri clll oroltll'nl 37/44 O.02-U.O 34/47 a.02-~3.0 11"1 a.02-~~.O
1,1.2-~r'cnlgrD.tnan' 2144 0.1-0).12 1/47 tJ.H 1/91 1).1-~.14
Tltr~cQlorOlthlnl ~4/44 a.03-i.2 ~bJ47 O.02-~.1 110/91 0.02-3.1
Chlaraltllinl 0/44 1/47 0.43 1/91 0.43
Chlarafan 3/44 O. 2~." 8/47 0.03-1i~ 11/91 0.03-1.7~
-
1,2-dicnlara.th.n, 2144 0.1 1/47 Q.O~ ' 3/~1 O.~~.l
Srolodichlcrol,thinl 0/44 3/47 O.18-~.4a ~/n . 0.18-1.111
t.2-dichlQroor~~1 0/.4 -_. 1/47 2.0 1/91 2.0 0
Diorc.~clllQrcllt~in. 0/44 1/~7 0.07 1/91 0.07
CI11orablnnn. 1~/44 0.3-1.0 ,0/47 1~/91 0.3-1.0
-
- -
1,~-dicnlarQolaz'n. i&S lIS "3147 0.GV-~.16 - 3/41 O. OV~o1'
Tricbloroilcarcaothinl ~S :15 3147 0.11-!.2 :/41 0.17-1.2
:
Any at tn. iac.. Glttet.G 42144 ~2J41 84/91
XS - Met 5.., lid
All canclntriticnl ." flportla il ~9/1.
Frequency show the number of detections over tbe number of sam~les analyzed.
~anqe Jhows ~ r&D~. Qf a47i_'M ~alu~s at eacn loc4tioa.
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T"olt: 1-B
Suwhdry of Plume 1 GroundudLt:r Udld
I::au Cldlre ~LllIlc1pdl W~ll f'leltl Sltt:
Phi" ~ Ph... 1 Iohl
i _._-----------------~~------------~- ----------------------~------------- --~---------------------------------
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I 6eoulric 6i.:oLlilric a.ol.tr i,
PARAKETER I fn4"K, Rlnllllvljl "unlA~g.1 Frtqu.ncy hnglhvljl IiHIl l.vg.1 Ff"qu.nc, R1n~llnWI Kuntavi.1
--------------------------~--.-------------------------------------------------------------------------------------------------------------------------------
Tr Uil-I,2-d'chlorolthlnl 2/iO 0.02-0.18 0.01 , 0110 I 2120 0.u2-0.18 0.01
III-dichioro.thani 9/10 0.01-8.0 0.55 ~IIO 0.05-J.~ 0.24 15120 0.04-8.0 O.U
Cli-I,2-dichloro.tblnl 5/10 0.01-0,11 0.04 5110 0.01-0,29 0.05 10120 0.01-0.29 0.04
I.I-dichloro.t.,nl 8116 0.01-4.] 0.211 51&0 0.29-1.2 0.09 13120 0.03-4.3 0.16
II I II-tricblorolthanl 81&0 0.12-'" D 2.0 10110 0.04-2L.3 1.4 18120 0.04-U.8 1.1
Tricblorolth.n. 10113 0.10-21. 0 LA 10ltO 0.01--13.0 0.69 20120 0.03-2 t. 0 I.t
1,li2-trlc~IDrolthan. 2/10 0.01-0. t2 0.011 0110 2120 0.01-0.12 0.03
T.trachloro.th.n. 8/10 0.04-0.8~ 0.11 5ltO 0.11-0,U 0.11 13/20 O.04-0.G~ 0.11
Chli)rolthaDI 0/10 1110 0.J2 0.21 1110 0.32 0.12
Cblurofor. 1110 0.61 0.04 OltO 1120 6.61 0.01
1,2-.'chloro.thlnl OltO OltO 0120
8r ".odi,'1 orOllt'... 01t0 0110 0/20
1,2-.'chlora,ro,anl 0/10 OltO 0120
DI~(OIOt'laro..t'an. 0/10 OltO 0/20
Chlarohlunl 4/10 0.39-0.14 0.111 0110 4/20 0.:19-0.14 0.111
1,.-.tcblarD~lnlln. fiB NS N& 1/10 0.011 0.11 1110 0.08 0.11
TrlchlorofIDurD.lt~a.. N8 N8 MS 0110 OliO
WS - Not &a.pll.
All conc'Atratlonl .r. fl,ortld 'I uiJI. .
~OT[I R.ngls Ind gloaetric 1.101 ~erf derive. by uiiDI lhe
I~.rlg' vilul frol l~t I,.iluilirith..tic at&n tlbll..
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TdlJle 1-(,
Summary of Plume 2 Ga.oundwatcr OaLI
£dU Cl~l.e Munlcipal Well field Site
-- - ...-------------------- -....-------.- --------------- --- ----- ---- -- -- - - ------ -- ------- --------...--- -- ---- -------- -----.- - -.... - -------- -- - - -.. -- -- ---- -------- ---
PARAKETER.
I Phlll I
I ------------------------------------1
I 'Iolltrlc
1 FrtlqulAcy Ran'lt.v~1 ",'1111111). t
, ' Phlll ~
. ----------------r-------------------
6uclittrlc
Frequlnty R'n'ltlv~1 "~i"tIVIJ.t
lotd
---------------------~--------------
f n.qulfncr
Rin,. hl/~I
a.alltr i ,
"lint II/g. 1
Tr 1l1i-1,2-dichiOrDllbllll 0/1 0/22 0/29
I,I-dichloro.th.nl 3/1 0.06-0.lt8 0.0" 11/22 0.01-.,] 0.35 10/29 0.01-4.3 0.23
~i,-1,2-di(hlorolthl.1 1/1 0.06 0.01 11122 0.02-2,1 0.03 12129 0.02-2.1 0.02
1,ldichiaro.lhlnl 4/1 0.02-0.09 0.02 '15/22 0.01-1.0 0.08 19/29 O.OI-J.O 0.0&
1,1 I I-lrlcblorallhln. 611 0.12-1. 9 0.39 20/22 0.0]-128.0 1.4 a/29 0.03-128.0 1.0
TrichlarOlth.nl 7/1 0.0]-4.11 0.61 19/22 0.12-9.6 0.9 211/29 0.03-9.6 0.83
1,1,2-lric~lorallhanl 0/1 1/22 0.14 0.05 1129 0.14 0.05
T.trlchlarolthlnl 6/1 0.04-0.12 0.011 11/22 0.02-1.1 0.09 21129 0.02-3.1 0.08
Chi I)rDlthlal 0/1 0/22 0/29
Chi orDfon 2/1 0.08-0.16 0.1 5/22 0.02-l.l~ 0.05 1/29 O.02-1.1S 0.011
1,2-~ithloroltb.nl 0/7 1/22 O.O~ 0.02 1/29 O.OS 0.02
8ro.odit~lorollt~lnl on ]/22 0.18-0.48 0.06 3129 u.18-0.U 0.01.
1,2-ditblDropropanl 0/1 0/22 0/29
DihrDloc~larollt~anl 0/1 1/22 0.01 ~.05 1/19 0.01 0.06
Chll1rohnunl 1/1 0.4-0.14 0.21. 0/22 1/29 0.4-0.14 O.I~
1,~-ditbIDrDblnllnl M9 liS liS . 1/22 0.14 0.12 1122 0.14 0.12
lrichlDrofloUlDlllblnl itS lIS 115 2/22 0.9-1. 2 0.07 2/22 0.9-1.2 0.01
NS - Not Sllplld
All tDntlntratiDnl .rl f.port.d in uQ/I.
NOTE, R.nqti ind qto.elrl( .e.ns Mer, deri¥e~ by uiikg the
II/erigl vilut frat lbe ...ilui/irilh.,li( lei" tibLe,.
"
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~~(
FIGURE
4
DEF'JNI'l'lON of PLUl-1ES
EAU CLAI W',\MUNICIl'AL WELL FIELD S ['rE
.~
Q
WWO\
..
p.
8M,....- N
o
.
'1000
c:::-.-:::::::::2
fEET
LEOI:tlO
Ulnlmum~on'our ,18 (pp~~
Contou'ln'ernl 11 (ppbl
..l1:li. ~'ound"'~I.' DI~ld.
~ 01,,"1101\ o' O,ound...,.,
r10w
~t~
,
II
..
-------
5
glacial outwash in the area of Plume 1 ranges from 35 to 80 feet. The
estimated volume or contaminated groundwater in Plume 1 is 1.9 x 108 cubic
feet. Plume 2 has an area of about 2.0 x 107 square feet. The saturated
thickness of the glacial outwash in the area of Plume 2 also ranges from 35
to 80 feet. The estimated volume of groundwater of Plume 2 is 2.6 x 108
cubic feet.
Surface ~ater
To determine if contaminants are present in the surface water either as a
source of well field contamination, or as a result of groundwater discharge
into the Chippewa River, samples (SWOl, SW02. SW03) were collected frQm the
river upgradient. adjacent ~O, and downgradient from the municipal well
field. The sampling locations are shown in rigure 5. A brief summary of
the results is given below:
SW01 (upgradient)
No contaminants of concern
SW02 (adjacent)
l,l,l-Trichloroethane (0.045 ug/L)
Trichloroethene (0.02 ug/l)
Cnlorobenzene (0.031 ug/L)
SW03 (downgradient) -
Trichloroethene
(0.02 ug/L)
While some low levels of VOCs were detected in the samples, evaluation of
these data indicates that the swrface water in the study area is
substantially less contaminated than the groundwater, and therefore ;s not.
likely to be a source of the well field contamination. Furthermore, .
extensive pumping of the well field prevents"groundwater discharge to the
river, thus leading to the conclusion that the low levels of contaminants
detected in the river are unrelated to those in the groundwater.
Q
Source Investigation
A three part investigation was performed to identify possible sources of
the groundwater contamination. The first part was an industrial survey
consisting of on-site inspections of several industries that may use
solvents. ihe survey focused on the Eau Claire County Airport and Chippewa
Valley Industrial Park located east of the airport and west of U.S. Highway
53. The survey identified four locations warranting on-site investigation
and sampling. The second part of the source investigation ~as a semi-
quantitative s011 gas survey of possible source areas at the various
industrial facilities. Finally, a soil sampling program was implemented to
confirm the presence or absence of residual VOCs in the surface and
subsurface.50i1 boring samples. ~onitoring wells were installed in the
soil borings and groundwater samples wer~ collected.
The semi-quantitative soil gas data indicated the possibility of VOC source
areas within these facilities, but there was no overwhelming or clear
evidence to guide the soil sampling program. Neither the surface 50il
sampling nor the soil boring sampling found any evidence of. residual soil
contamination that could represent a source of the groundwater
-------
." .
I
FIGUFIE 5
D..
-~ N
.
~r~ .~O()
-------
6
contam; nati on in th2 study area. The '101 at; 1 e organi c :cmpounds fauna to
be predominant in the groundwater contamination were not found in any of
the surface sailor soil boring samples. with the 90S sible exceDtion If
chloroform. Thus, none of the possible source areas identified by the
industrial survey and the soil gas survey could be confirmed to have any'
role in causing the groundwater contamination in the study area.
Groundwater samples from downgradient monitoring wells at the potential
source areas detected some VOCs' at higher concentrations than in wells
;rrmedi.3tely upgradient. However, !11onitoring ""ells furt!1er !lDgradie~t I)f
these facilities also aetected VOCs.
In light of the results from the groundwater, surface water, and source
investigation ryerformed during three ohases 0f ~he R!. it ~as ~eter~ined
~hat 7urther source control investigation was 10t 5ustified. ~ence ~he
remediation of contamination at the ECMWF site is limited to tne
groundwater in the form of two plumes (Plume 1 and Plume 2).
Other Potential Sources
Another potential source of ~he VOCs contaminating the grounawater ~n :he
study area ;s National Pr~sto Industries. Inc. (NPI) , This facqity. which
is located ~ast or the industi'"~dl ;Jar!(, ;s lis~ed '1n::he ~!at~tJnd1
Priorities List (NPL) as d site separate from che '::CMWF site. riPI is
currently undergoing its own RIfFS. Nevertheless. available information
suggests that it could be a source of the groundwater contamination with
which this study ;s concerned.
..
VI.
SUMMAR; OF RI SlS
A Public Health Evaluation (PHE) was performed as part of the RI to .
evaluate the potential impacts to human healtn ana the environment,
assuming no further remedial action is taken at the site. As discussed
earlier, an air stripper ;s currently on-line :0 remove 'fOC:: ;:iom :nun~c~pai
water until the expiration of the (IRM) ROD in June 1990.
The exposure pathway of concern for human exposure includes ~ngestion and
inhalation of the hazardous substances in the groundwater. T~e ~oou~ation
affected includes those connected to the municipal water supply and prlvate
well users located in the areas of Plume 1 and Plume 2. The human exposure
pathways for current and future use are identical, for if the air stripper
was taken off-line. the municipal well users would be exposed to the same
chemicals as private well users in Plume 1.
The individual contaminants are separated into two categories Jf :hemi~a'
toxicity depending on whether they exhibit noncarcinogenic or carcinogenic
effects. The PHE identified the contaminants of ~onC2rn in ?lumes 1 dnd 2
whicn are carcinogens. Tn; s '",as de"1:enninea ';y :he .:;;mcer po-c:::r.c:' ..~C".:or
which was used to estimate the iifetime excess caici~ogeni~ ~is~
-------
..,.
I
associated with low-dose exposure. No human health risk was found to be
associated ~ith noncarcinogens. Carcinogens of concern are:
Plume 1
Plume 2
l,l-Oicnloroethene
Tetrachloroethene
Trichloroethene
l,l,-Oichloroethene
Tetrachloroethene
Trichloroethene
Chloroform
The carcinogenic ri sks are theoretical quanti fications, and are reported as
excess lifetime cancer risks. Excess iifetime cancer risK is defined as
I:he i ncrementci 1 probaaii 1 ty .Jf ]e"Cti ng .:ancer cC1Dpared to the arOaaOl! i ty
if no exposure occurred. For exampie, a 1 x 10-Q ~xcess lifetime cancer
risk represents an exposure that could result in one extra cancer case per
million people exposed. The cancer risk levels assume ingestion of two
liters per day of drinking water for 70 years.
The calculated cumulatiye 2XC2SS ~ifetime cancer ~isks resulting f~cm
exposure to chemicals of concern in the groundwater are presented below:
~ i htime
i:..~C~S .s
:Jncer ,~iSK
Mu 1 tip 1 e
Pathways
Air Stripper
effl uent
Plume 1
Plausible
Average Maximum
Average
Plume 2
Plausibl~
Maximum
,
Ingestion of Water . 5x10-7 4xlO-6 8x10-5 2x10-6 6xlO-5
Inhalation while
showerii1g 1:<10-6 SxlO-6 1x10-4 2xlO-6 . vlO-d
L... .
To ta 1 2x10-0 ;:xro - 5 2x10-4 4x10-6 2x10-4
The cancer risk for the air strioper effluent is conservatively high. The
risk was based on using the lab detect~on limit of .03 ug/L for 1,1-
dichloroethene because this compound was not detected in the air stripper
effluent samples. Blending of the air stripper effluent with
uncontaminated water from the remaining municipal wells reduces the cancer
risk even further at the user's tap. The final remedy is based on the
risks calculated under the plausible maximum exposure scenario.
Environmental Assessment
No pathway cur~~"tly ~XiSt5 whe~~ 2nv~ronmental ~eceptors (fi5h and othe~
dQuatic 1 ire) in :he Chippewa ~i'Jer ma~f i:;e .::~posed to t;,e groundwat~r
con tami na ti on because grolJndwater di scharge to the Chi ppewa Ri 'fer is
prevented by the pumping from the well field. For the future scenario, if
pumping were to cease and groundwater discharge resumed, based on the
available toxicity data and estimated future concentrations of chemicals of
concern, potential impacts to fish and other aquatic life do not appear
1 ikely.
-------
-
~ir Striooe~ Air' ~mls31ons Assassrne~~'
The ri sx assessrner1t :?'al iJated ',,;he~her ~ publ ic heal th :.~r~at' exi sts under
the current-use conditions. The exposure pathway is the inhalation of
'::1emicais voLn"ilizea aUTlllg dir ~~hpper :7"~a"tl1en~ 0T :i1unicipai wd~r
until the expiration 'Jf the previous ROD in 1990.
ihe lifetime excess cancer risk for residents exoosed via inhalation to the
:~emic3Js of c~ncer~ r~leased to the air during the strippinq is 5xlO-i.
For carcinogens, E?A generally considers a risk range of 10-4 to 10-7 unit
cancer risk as acceotabl~ and generallv orotective of human heal th and the
-:r1'l~ r~nme!'1-:. ~cnc.3.r:~ ;;ocens 4er~ ~:iIJi1a :-:0-: :a .Jcsa J. ~::r,=at ::J :,uman
:~ea i :71.
Camoarison to ARARs
T:,e 0LiE ~lso ~ompar<:d '::,e concen"tr~t~ons 1;1 ,'l!Jme ::ind :'1ume 2 '..;~h
7~de~:~ ~:~d ::.::~ ~~~: ::=.::.~~ ~:- ~',:~'::.";:n"C :::<1 1..J1:7'"~~r": !::~
-\e~u ~ ~..~!::c:~-::
(ARARs). It '.4as round that the maximum concentration of trichlor1e'tJ"le!1e in
~Gt:': ~l ume~ ~_v:::e~~~ ~!1~h '=~~~!'"~1 ".!'1(! S':.1!:~ ~,?,~P: ~~d "':~e ~~_~';~!lm
c:nc~ntra~:ons of ~,l-Q1C~loroethene and :2tiaCniJr~e!hene -:n ?iume 2
exceed a Stats ARAR (Table 2). In addition, the State re-gulates voe
emissions from air stripoers. A discussion on the voe emissions is
present~d in Section VII!, Compliance with ARARs.
VII.
DESCRIPTI0MOf ALTERMAT1VES
"
The Feasibility Study (FSi was ;~itiated in,January 1988 to evaluate
al ~~r~ativ~ r~~i~l ~c~ion~ for the 1Toundwater contamination at the ECMWF
3ite. 3ased on the results of the RI and the P~E, the following specific
:~me1~al act~on goa1s ",er~ e$:Jbi~5~e,j ~;:;j"'a ;inal ""<:!T!e~y at ~jje ::':~wr
si te;
o To assure public health ~rotect;on from the groundwater by
:~~'!~!1t~ ,,~~ 1_1ges-:~ Crt ~j1C : "na ~ :~.-:~~" :7 '.fa-:~"" -...,;:~ -:~r1t:;mi ~aj11:
concentrations:
1. In excess of their MCLs or Wisconsin Health Advisories.
2. ~ith a ~~~ulat1v~ l1fetime excess cancer risk of greater than 10-6,
o Remediate the groundwater to a cumulative lifetime excess cancer risK
of 10-6.
!~ 'iariety of Cccnnoiogi?s :Jia-: ',of QUId daaj'~:)S "i:11~ .-~e
-------
Clleult cal
l' Afill::
L
aJiPARISOU OF I'OTEHTlAl. APPlICABI.E OR REI.E'lANT AlID APPIlOPR I HE CRITERIA 'W GROUHIMAn:R
Aim TAP WAl£lt OOIiCENIRATlONS AT TIlE UU CLA1RE SITE'
.(11111 U Lilr)
Concenta:aLlonw
rederal CelLeri.
Stat.. Cdt.riA
.!
t'1.ulH 1
l' hWIa 2
tr_at.ad H>-m1c11J/11.
W",t~rl
t£LG.
t£Lb
WAli
G~ometd a
Hean
u..Jow6tr1c
MOAU
Hu'lOW!
WGK}S c
Hax111JJ11l
----- .-
0&:&un1c (''henUcab:
Chlocob"nzene
Chlol'O( u t'm
l,l-D1chloroelhane
1.1-D1c1.loroet.hane
f.1r I, 2 - D1chloroet.hene
i.Hi.!! -1 ,2-Dlchloroet.h8na
1.1.1-Tdchloro8lhane
T d chla,;oethene
'flola:ach1.oco8t.hene
I noqSAI\ i 9 ChenUcAla:
Iron
HAil 1:\ Anu..e
860 0.11) 0.14 IIC tIC -J
L100 1.31Z10
Cl00 HC IIC 0,06 1.8 HC -2
850 0.J6 6.0 0,21 4.3 2.011:1°-2
7 1 0.24 7 0.16 4.J 0.05 3.0 <3.011:10_,.
870 O.O~ 0.29 0.02 2.1 3.61110_5
1110 O.OJl 0.18 lie: IIC 8.0ul0-2
200 200 20£1 20£1 1.1 65 0.92 130 2.0JrlO-3
o 5 1.8 j 1.1 21 0.11 9.6 ,.3.0JriO-2
80 1.0 20 .0.11 0.86 0.01 3.1 2.£111:10
h~OO
50
HC
62
140
29
HQ
24
2,600
HO
IIC
a
"'11ululIIl Cont.am1nant. Ltovel. GOAL (Not ARAR),
hHlutiDJU,1 ConlAIDlnant. Levu 1., axe.pl' where not.ea).
c\-l1liconaln Publio Hulth Oeoundwol.a Quality StamJudll UlhGona1~1 Admlrl16Lr'atlvtJ Cl.id~". Chap. HO).
dWlIICOUII1n Advhory (WlacClI\t>!1I Ad1uiulAt.raUv6 Coda, Chop. 109).
apropoda:sd.
fSt.oudHd 18 for Lot.al t.rlhaloouIUI..noa,whlch include broraoform.chlorotorll,dlchlo/obromomethIJ.Cl8 and chiorodibrolllomethane.
I!Conce'itl."atlonll ..r. Lhe RIdan COficeutrc.Llona reported 01: 65lirut.ed lor t;hcmlc.la ill iUwd':pAl Wlit.er l['o..lad to r&AllOva orllin!c chem1olll.iI. ...
ruport.od 1n TAble 5-1.
IlslJGonJliry H4JIlrwm ConlAtllln..nl Leval.
lIi~ .. N.,L 8 chomlcol of pot-Blltlut COl1curn In lid a pl.ulIIlI 0.: till d wutlu-.
o
-------
9
Alternat1ve. An alternative that involvea containment was no~ considerea
for this site because containment was not appropriate for the two plumes of
groundwater contamination.
Alternative 1 - No Further Action
Capital Cost:
Annual O&M Cost:
Total Present ~orth
Time to Implement:
SO
5333,100
S578,300
None
Cost:
.~.1:2!"''''J.:~\!e ~ f~ ~~e \Jo 1c:~cn ~1:2~~at:~..'~w ,-:-'Jr 'J~lJme .~., :-:---:: ~e1'::; ~':.,
11, 15, 16, and 17 located in the nor"th '....e1i fie1d 'liould continue to :Jump
contaminated groundwater to the existing air stripper. ireated groundwater
from the air stripper would be pumped to the existing Eau Claire water
system. ihis action will last until the expiration of the existing Record
of Decision an June 10. 1990. Beyond this time the~e ~i'l be ~o fur~her
remedial action taken CQwaras tne grounawater. For ?lume 2, no r~meQiai
Jction ~i" occur. This alter,ative is c~ns~dered a has21i~e sC~~2r~o ~J
~f'~ ~:h ~':-.~er .i! t2!'a.t~ '!t~S :.:lr1 :2 ::;:1Da;a~d..
Alternative 2 - Onsite Treatment, Alternate Water Supply, and Groundwater
~on;tor;na.
.
Capita1 Cost:
Annual O&M Cost:
Total ?resent ~orth
Time 'to Implement:
$318,500
S333,100
53,699.,900:
40 Years
.
CJst:
Alternative 2 provides cleanup of both plumes when they enter the north
...el1 rieid. CIty we!ls 10, 11, 15, 16, and 17 i(1 the ,10rtl1 ",eii fieia
would continue to pump contaminated groundwater to the exi~ting air
stripper. Treated groundwater will be pumped to the Eau Claire water
system. Based on pl ume migration travel times, it ;s estimatsd that it
-ouid ~3i
-------
10
Alternative 3 - Onsite Treatment, Extraction, Discharge, Alternate Water
Supply, and Groundwater Monitoring.
Capital Cost:
Annual O&M Costs:
Total Present Worth
Time to ImDlement:
$896,500
:5356 ,400
$3,347,600
9 Years
Cost:
Alternative 3 provides cleanup of Plume 1 when it enters the north well
field, and provides simultaneous cleanup of Plume 2 through the use of
groundwater extraction wells located in Plume 2.
For Plume 1, city welis 10, 11, 15, 16, and 17 in the north well field
would continue to pump contaminated groundwater to the air stripper.
Treated water would be discharged into the Eau Claire water system. This
action would last until Plume 1 is cleaned up, which is estimated to take
nine years based on estimated plume migration travel times.
One groundwater extraction well installed in Plume 2 would clean up the
groundwater concurrent with Plume 1 in an estimated timeframe of 9 years.
The extrac~ed groundwater will be discharged into the Chippewa River
without treatment.
The alternate water supply and groundwater monitoring components are the
same as for Alternative 2.
Al tcrnative 4 - Ons ite Treatment, Extracti on, Di scharge, Alternate Water
Supply, and Groundwater Monitoring.
Capital Cost:
Annual O&M Costs:
Total Present Worth
Time to Implement:
Cost:
$1 ,214,200
$396,700
$3,030,200
5 Years
Alternative 4 is designed to remediate the groundwater contamination in
both Plume 1 and Plume 2 in an accelerated timeframe of 5 years.
For Plume 1, contaminated groundwater would be pumped both by city wells
10, 11, 15, 16, and 17 in the north well field and by two groundwater
extraction wells located in Plume 1. Groundwater from contaminated city
wells would be treated with the air stripper and discharged into the Eau
Claire municipal water system. Groundwater from the two new extraction
wells in Plume 1 would be discharged into the Chippewa River without
treatment. Two groundwater extraction wells would also be installed in
Plume 2 to cleanup this plume concurrent with Plume 1. Extracted
groundwater would be discharged to the Chippewa River without treatment.
The alternate water supply and groundwater monitoring components are the
same as Alternative 2.
-------
11
Factors Common to ail the Alternatives:
The treated groundwater from the air stripper will provide safe drinking
water to the public that does not exceed Federal or State drinking water
stanaards. State of Wi scansi n ai r poll uti on control standards for
emissions from the air stripper will be followed.
ractors COrmlon for ..\1 ternati'les 3 and 4:
A Wisconsin Pollution Discharge Elimination System (WPDES) permit will be
obtained for the discharge of the extracted untreated groundwater to the
Chippewa River. ~s~imated vac concentrations Nill comoly wi~h both ;~deral
and State ARARs and ~PDES discharge limits.
The number of private well users is based on current information.
actual number will be confirmed during the remedial design.
The
'HIL
SUMMARV Of ca~ !.\RAT!i1E .:WAL'1SIS I)f AlJERMT:'\!k::S
The four alternatives assembled ~ere evaluated based on the following nine
criteria:
- Overall protection of human health and the environment;
- Compliance with all federal and state applicable, or relevant
and appropriate requirements (ARARs);
- Short-term effectiveness;
- Long-term effectiveness;
Reduction of toxicity, mobility, or volume;
- Implementability;
- Cost;
- Community Acceptance; and
- State Acceptance.
A summary of the relative performance of the alternatives with respect to
each of the nine criteria is provided in this section.
Overall protection of human health and the environment
Alternatives 2, 3 and 4 would all be effective in protecting public health
from ingestion and inhalation of contaminants detected in the groundwater
by providing Q safe, reliable, potaole water supply to those residents
currently connected to the Eau Claire municipal water system, as well as
those using private water supply wells within the area of groundwater
contamination. T~is is accomplished by trea~~ent with the existing air
stripper of contaminated groundwater from five munic~paj wells prior to
blending with uncontaminat~d water in the distribution system and
connection of private well users to the municipal water system.
Environmental receptors are not affected by the groundwater contamination.
Alternative 1 does not provide adequate protection of public health since
this alternative will last only until the expiration of the IRM ROD on June
10, 1990. This alternative will not be considered further.
-------
12
To evaluate. if a pubiic heaith threat is present from the vac emissions
released into the atmosphere from the air stripper a risk assessment was
performed. For Alternative 2, the FS evaluated the risk associated with
air emissions for the maximum anticipated influent concentrations based on
maximum groundwater concentrations found in Plume 1 and Plume 2. The
lifetime excess cancer risk was found to be 2 x 10-6. The U.S. EPA Air and
Radiation ~ivision evaluated :he ~isk for Alternatives 3 and 4 in which
only contaminants in Plume 1 w6uld be treated with the air stripper. Using
the geometric mean groundwater concentrations, there is an estimated total.
peak cancer risk of 8.6 x 10-8. Using the maximum groundwater
concentrations results in a total peak cancer risk of 2.3 x 10-6.
~oncJrcinogens were found not to present a ~hreat to human health.
Alternatives 3 and 4 discharge untreated groundwater to the Chippewa River.
The U.S. EPA Air and Radiation Division also performed a risk assessment on
the volatization of VOCs from the river to the air. The total peak
anticipated cancer risk for inhalation at the discharge point is
6.7 x 10- 7 .
The above levels are within the 10-4 to 10-7 unit cancer risk range that
EPA generally considers protective of ~uman health and the environment.
Therefore, the results of the air risk assessment indicate that the public
health risk due to air emissions from the air stripper and volatilization
of VOCs from the Chippewa River present a low level of risk.
Radiation problems in air emissions can originate from air stripping if
concentrations of radon-222 and thoron gases are substantial in the
groundwater. There has no~ been any testing" for radon or thoron in the
groundwater at the municipal well field. However, the geology of the area~
and the outwash aauifer being used, are not likely to generate radon. In
order to verify this, the municipal water will be sampled for radon-222 and
thoron during the design phase for the remedial action.
Compli~nce with ARARs
Each or the 4. alternatives ~as assessed as to whether it compiied with
State and Federal Applicable or Relevant and Appropriate Requirements
(ARARs). All alternatives would be required to meet the following ARARs
upon implementation:
o Safe Drinking Water Act (SDWA) Maximum Concentration Limit (MCLs)
o Wisconsin administrative code chapter NR109 (governs water quality
from air stripping);
o Wisconsin administrative code chapter NR140 (applies to all department
regulated groundwater activities);
o Wisconsin administrative code chapters NR400-499 (regulates air
emissions from air stripping);
o Wi sconsi n admi nistrative code chapter NRlll (regul ates well treatment
and distribution design for community and municipal supplies); and
o Resource Conservation and Recovery Act (RCRA) Part 264
(regulates groundwater monitoring program).
-------
13
Alternatives 3 and 4 involve comDonents of groundwater extraction and
discharge of untreated groundwater to the Chippewa River and would also be
required to meet these additional ARARs:
o Clean Water Act (CWA) NPOES requirements listed in 40 CFR 122;
~ CWA Ambient Water Quality Criteria for Protection of Aquatic Life;
o Wisconsin administrative code chapters NR102, 104, 200, 217, and 219
(rp.gulates discharge to surface water, including setting effiuent
limits. stream classification/standards, and sampling/testing
methods). The state wi 11 issue a WPOES pennit;
o Wisconsin administrative code chapter NRl12 (regulates any wells
extracting greater than 70 gpm);
~ ~isconsin administrative code chapter NR11S-118 (regulates
construction activity in the flood-plain); and
o Wisconsin statute chapter 30 (Permits, approvals. technical
standards).
~isconsin administrative code chapters NR400-499 regulate air =missions
from the air stripper. Controls are tripped if air stripper Ifoe emissions
exceed 3 lbs/hr or lS lbs/day. In addition, if the air stripper emits
greater than 5.7 lbs/hr the stripper is subject to a permit which makes it
subject to 85 percent control s. Actual fiel d data of the infl uent to the
air stripper will be used to determine whether the above standards are
exceeded.
The U.S. E?A Air and Radiation Division estimated total VOC emisS10ns for
the air stripper under worst ~nd average case conditions using the
avail~ble groundwater data. For Alternative~2, under average conditions,
total VOC emission rates of 0.36 lbs/day may be encountered. For worst
case conditions (maximum VOC groundwater concentrations) a 16.44 ibs/day
(.69 lbs/hr) VOC emission rate may be encountered. For Alternatives 3 and
4 under average conditions, total '/OC emission rates may be 0.36 lbs/da:'
and under the worst case scenario (maximum VOC water concentrations). 9.i9
lbs/day (.41 lbs/hr) may be encountered.
~
The projections of average and worst-case scenarios are very conservative
and predict that controls may be needed under the worst case scenario for
Alternative 2. However. whether controls are instituted will be determined
from actual field testing of the influent to the air stripper. In
actuality the maximum concentrations (worst case scenario) will probably
not be found in the influent data from the well field.
No waivers from ARARs are anticipated at this time.
Short-term Effectivenes~
Alternatives 2, 3. and 4 provide a high degree of short-term effectiveness
in achieving prompt protection of human health with no significant adverse
impacts from the implementation of the remedy. Immediate protection is
available to residents currently connected to the municipal water system.
The connection of private well users to the municipal supply is estimated
-------
14
to take approximately 6 months for those requiring construction of' water
mains. During the interim period, these private well users will be
supplied with bottled water. For Alternatives 3 and 4, the installation of
extraction wells and discharge of untreated water to the Chippewa River
will decrease the time until the groundwater is remediated and full
protection is achieved. Implementation of these components will present no
significant adverse impacts to the community or construction workers.
The implementation time to provide protection to public health will be the
same for Alternatives 2, 3 and 4. The expected length of time to complete
the groundwater remediation would be the following for each alternative:
Alternative 2 - 40 years
Alternative 3 - 10 years
Alternative 4 - 6 years
In Alternatives 3 and 4, an additional year is added for the design and
construction of the extraction weils and discharge ~echanism to the
Chippewa River.
Lonq-term Effectiveness and Permanence
.
Alternatives 2, 3, and 4 will remediatethe contaminated aquifer to the
target cleanup level (TCL) of a total excess lffetime cancer risk of 10-6.
Therefore, the magn; tude of resj dual ri sics associ ated ~ th these
al ternatives will be at the 10-0 ri sic level. After the TCL has been
reached, groundwater monitoring will be conducted for 3 years to assure the
certainty that the remedy successfully cleaned up the groundwater. Private
well users will be connected to the Eau Claire Municipal water system and
groundwater monitoring for VOCs will continue after the remedial action is
completed. If VOC contamination is detected after the groundwater has been
remediated, the air stripper will remain at the water plant to be put bacx
o n- 1 ; ne .
Reduction of Toxicity, Mobility or Volume
Alternative 2 (the use of the air stripper) and Alternatives 3 and 4 (the
use of the air stripper, extraction wells, and discharge to the Chippewa
river) will reduce the concentration of contaminants in the aquifer and
eliminate the primary exposure route of using contaminated water for
potable purposes. However, there will not be a reduction of toxicity,
mObility and volume of hazardous constituents beyond those occurring
naturally through dilution, dispersion, adsorption, biological
degradation, and ultraviolet radiation. Therefore, none of the
alternatives reduce toxicity, mobility, and volume of hazardou5
constituents through treatment.
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15
Implementability
The implementability of each alternative is based on technical feasibility,
, administrative feasibility, and the availability of services and material
for the alternative. Allor the alternatives are technically feasible and
involve technologies which have been used regularly in the past and have a
demonstrated performance record. Each alternative would use the existing
air strioper, which has achieved satisfactory reductions Jf VQCs.
Alternatives Z. 3, and 4 include a groundwater monitoring ~rogram, provide
bottled water, and allow for connection to the municipal water system and
the construction of water mains. Alternatives 3 and 4 involve construction
of extraction wells and discharge of untreated water to the Chippewa River.
The FS evaluated two methods of conveying the extracted groundwater to the
river which are: 1) use of forr.e mains and 2) the combination or usi~g the
existing storm sewer and force mains. According to ~he City of Eau Claire,
the storm sewer will not be able to take on the additional flow and
therefore will not be considered further. Whether a submerged or an
aerated outfall discharge system to the Chippewa River is used will be
evaluated and determined during the remedial design. The discharge system
will comply with WPOES permit requirements, and the system most cost-
effective and protective or human health and the environment will be
implemented. The ~POES discharge permit and construction permits from the
State are administratively feasible. fn addition, EPA plans to obtain
approvals from the City and County of Eau Claire. The services and
materials required for each alternative are expected to be readily
available.
Q
80th the State and City have e~pressed concerns on ~hether the extraction
wells installed in Plume 1 for Alternative 4 will cause substantial induced
inflow from the Chippewa Rive~ and subsequently require additional
treatment of the municipal water supply to remove iron and manganese. The
remedial design will evaluate and determine extraction well locations to
minimize this possibility.
A cost summary for each remedial alternative is presented below.
assume use of the force main discharge to the Chippewa River.
The costs
COST SUMMARY
Annual Total
Assembled Capital Operation and Annual Present
AlternativQs Cost Maintenance Monitoring Worth
1 0 333,100 58,500 578,300
2 318,500 333,100 58,500 3,699,900
3 896,500 356,400 58,500 3,347,600
4 1,214,200 396,700 58,500 3,030,200
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16
Community Acceptance
Community response to the alternatives is presented in the responsiveness
surrmary.
State Acceptance
The State of Wisconsin has concurred with the selected remedy presented
below.
I"
A.
SELECTED AlTERUATIVE
Based on current information, the U.S. EPA and the WDNR select Alternative
4 as the most appropriate final remedy at the Eau Claire Municipal Well
Field site. The significant features of this remedy are as follows:
o Treat contaminated municipal water ~ith an existing air stripper;
o Provide municipal water to private well users within or near the
area of groundwater contamination;
o Install groundwater extraction wells in the plumes of contamination;
and,
o Discharge untreated groundwater from extraction wells to the Chippewa
River.
Target Cleanup levels
For carcinogens, U.S. EPA generally considers risk of 10-4 to 10-7 unit
cancer risk as acceptable and generally protective of human health and the
environment. The total additive potential risKs at the site are 2x10-4 for
ingestion and inhalation of groundwater from both plume 1 and plume 2.
Since the total additive potential risks from the site are greater than
10-4, the target cleanup level for the remedial action will be health
driven, and protection will be provided to the additive 10-6 risk level at
the potential receptor.
Listed below are the TCl's that need to be reached for each contaminant to
achieve the a.dditive 10-6 risk level. These concentrations are based on
current groundwater data. However. during the remedial action) the TCl for
each consti tuent may change in order to reach the add; the 10-0 ri sk 1 evel .
Plume 1 Max. Cone. TCl
Trichloroethene 21.0 0.5
1,1-Dichloro-
ethene 0.9 0.1
Tetrachloroethene 4.3 0.01
Reouirements
** Federal' Wisconsin
Target Risk MCls WGWQ£ WA
3.4 x 10-7 5 1.8 5
2.5 x 10-7 7 .24 7
4.6 x 10-7 1 20
1 x 10-~
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17
Requirements
** Federal ~isconsin
Target Risk MCLs WGWOC WA
Plume 2
Max. Conc.
TCL
--
Tr;chloroethene
Chlorofonn
1,1,-Oichloro-
ethene
Tetrachloroethene
9.6
1.3
3.0
3.1
0.4 2.6 x 10-7 5 1'.8 5
0.06 2.4 x 10-7 100* 100*
0.007 3.6 x 10-7 7 .24 7
0.09 2.0 x 10-7 1 20
1 v 10-~
A ..:.
Concentrations in ug/L
Maximum Contaminant Level. (MCL)
Wisconsin Public Health Groundwater Quality Standards (WGWQC)
Wisconsin Advisory (WA).
*Standard is for total tr;halomethanes.
--A standard has not been developed for this chemical.
**Target risk includes both ingestion and inhalation risk..
The detection limits for the Special Analytical Services - low detection
limit analysis are higher than the TCLs for tetrachloroethene in Plume 1
and chlorofonn and 1, 1-di chl oroethene in Pl ume 2. Therefore, EPA wi 11
cleanup the groundwater to non-detect for these compounds and continue to
pump and treat for a period of time beyond the non-detect to assure that
the TCLs have been reached. .
Remedial Action and
Operations and Maintenance
The U.S. EPA ~il' pay 90 percent of the construction costs and the State of
Wisconsin will pay 10 percent. According to Section 104 of the Superfund
Amendments and Reauthorization Act (SARA), treatment or other measures to
restore groundwater to target cleanup levels are considered remedial action
of a period of up to 10 years. Therefore. U.S. EPA will pay 90 percent and
the State will pay 10 percent of the operations and maintenance (O&M) cost
of the extraction wells and discharge to the Chippewa River until cleanup
levels are reached or for up to 10 years, beyond which the State of
Wisconsin will assume full responsibility.
Additionally, U.S. EPA policy currently states that the 10 year provision
for Federal 90 percent funding applies to water treatment systems which are
part of a remedial strategy to restore an aquifer. Therefore, O&M of the
air stripper will be provided by the U.S. EPA and the State of
Wisconsin/City of £au Claire at a 90/10 percent cost share until aquifer
cleanup levels are reached or for up to 10 years, which ever comes first.
Beyond this the State/City of Eau Claire will assume responsibility.
However, with Alternative 4 remedial action is not anticipated to go beyond
this time frame.
In the previous ROD for the IRM, the City of Eau Claire provided the 10
percent match for the first year and then assumed all O~M for the 5 year
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18
life of the project. This no longer applies since the air stripper is part
of the final remedial strategy to restore the aquifer.
~rounawater monitoring for 3 consecutive years after the completion of the
remedial action will be considered O&M, for which the'State will assume
r':sDonsibility.
Statutory Detenlinat10ns
x.
~, .
P~otect;on of Human Health and the Environment
~ne seiected remedy provides protection of human health by providing a safe
rel iable water supply to those residents currently connected to the Eau
Claire municipal water system, as well as those using private wells within
the area of groundwater contamination. This is accomplished by treatment
w;t, the existing air stripper of groundwater from contaminated municipal
~e1~s or~oi to discharge into :he distribution system and connection of
orivate well users to the municioal water system. The prevention of
;':ges:"on jnd inhaiation of ",ater with contaminant concentrations that are
In excess of MCLs and 3tate nealtn advisories and with a total lifetime
excess cancer risk for all contaminants of 10-6 will be accomplished. In
additiont the groundwater will be restored in an estimated time frame of 5
years.
.
B.
Attainment of Aoplicable or Relevant and Appropriate Requirements
Alternative 4 will meet the following Federal and State applicable or
relevant and app~opriate requirements (ARARs):
1 Resource Conservation and Recovery Act (RCRA): 40 CFR Part 264
2. Clean Water Act (CWA): 40 eFR Parts 122, 125
3. Safe Drinking Watar Act (SD~A): 40 CFR Parts 141-146
4. State of Wisconsin administrative code: chapters NR 102, 104, 109,
111,112,115,118,200,217, 219t and 400-499.
~. Wisconsin Statute Chapter 30.
The Clean Air Act is not an ARAR, since there are no substances in the Eau
Claire groundwater plumes specifically regulated by U.S. EPA air statutes.
T~e Administrative Code chapters 400-499, air pollution control standards,
cire app 11 cable, because they reguJ ate emi 5S; ons from treatment systems.
,
.I. .
Resource Conservation and Recovery Act (RCRA)
. .::~, .:~i~ 254.:CO r=quin~s a ,;arrecti'te action monitoring program. Since
:~e ~au Claire Municipal ~ell Field is not regulated under RCRA, RCRA
regulations are not applicable, but rather are relevant and appropriate.
~he monitoring system will verify that contaminants have been removed by
'~r,e extraction wells. Monitoring may be discontinued if groundwater
3tandards are not exceeded for 3 consecutive years.
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2.
19
Clean Water Act (CWA)
The CWA is an ARAR since site groundwater will be discharged to a surface
water body (the Chippewa River) next to the site. Ambient Water Quality
Criteria (AWQC) are established for the protection of freshwater aquatic
organi sms. AWQC will be met at the di scharge poi nt, and a WPOES permi t
will be obtained for this discharge.
3.
Safe Drinking Water Act (SOWA)
The SDWA specifies MCLs for drinking water contaminants 3t public ''later
sUDplies. The SOWA is acplicaDle since regulated synthetic organic
chemicals exceed MCLs in the community drinking water supply aquifer (in
Plumes 1 and 2). Target cleanup levels will be below individual MCls, to
ensure that the cumulative risk is within the risk range.
4.
~;sconsin Administrative Code and State Statutes
The following Wisconsin administrative code (WAC) and Statute regulate the
preferred remedial activity to be performed ~t ECMWF:
a.
WAC chapters NR 400-499 - are air pollution control standards which
regulate emissions from treatment systems (in this case the air
s tri pper) .
b.
WAC chapters NR 109 - is a drinking water standard governing the
qual i ty of water from ai r stri"ppi ng towers.
WAC chapter NR 140- Wisconsin Public Health Groundwater Quality
standards. Applies to all department regulated activities;
standards include groundwater monitoring and sampling frequency.
o
c.
d.
WAC chapters NR 102, 104, 200, 217, and 219 - are regulations
covering discharge of ~astewater to surface ~aters (Chippewa
River). These statutes set effiuent limits, provide for discharge
permits, and give water sampling and testing methods. The state
will issue a WPOES permit, providing, as expected, all requirements
are met.
e.
WAC chapter NR 111 - is a regulation covering extraction well
treatment center and distribution system design and construction
standards for community and municipal water supplies.
any individual or
gpm or more. Concerns
of injection wells of
f. WAC chapter NR 112 - is a standard governing
combination or water wells which withdraw 70
include drawdown impacts and the prohibition
any kind.
g. WAC chapter NR 115-118 - are regulations covering construction
activities in river fiood plain areas. Generally, such
constructi on must be eval uated for any impact on upstream fl oodi ng
and no activity ;s allowed in the "floodway" including hazardous
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20
waste disposal. These statutes cover activities in both
incorporated or unincorporated floodplain areas.
h. Wisconsin Statute chapter 3D-Permits, approvals and technical
standards for construction of outfall in the Chippewa River.
As mandated, where State ARARs are more stringent than Federal ARARs, the
State requirements will be met at the completion of the remedial action.
c.
Cost-effectiveness
The selected remedy affords a high degree of overall effectiveness not only
in protecting human health by preventing consumption of contaminated
groundwater, but also in providing the greatest degree of short term
effectiveness by remediating the groundwater in the shortest time frame.
In addition, the selected remedy is the least costly of the alternatives
evaluated and therefore the most cost-effective.
D. Utilization of Permanent Solution and Alternative Treatment
Technoloaies or Resources Recovery Tecnno!ogies to the Maximum Extent
Practicable.
U.S. EPA and WDNR believe this remedy is the most appropriate solution for
meeting the goa)s of the final rem~dy at the Eau Claire Municipal Well
Field site. All of the alternatives evaluated in the detailed analysis
with the exception of the No Action alternative provide adequate protection
of public health and the environment. Alternat}ves 2 through 4 are
comparable with respect to 10n9 term effectiveness, reduction of toxicity,
mobility and volume, and implementability. However, alternative 4 provides
the greatest short term effectiveness and is the most cost effective.
Extracti on of the contami nated groundwater 'Nill permanent1 y restore the
aquifer and air stripping is the most appropriate type of treatment.
Therefore, the selected remedy provides the best balance among the nine
criteria and represents the maximum extent to which permanent solutions and
treatment are practicable.
E.
Preference for Treatment as a Principal Element
The statutory preference for remedies that employ treatment which
permanently and significantly reduces the toxicity, mobility or volume of
hazardous substances as a principal element is not satisfied.
Treatment '.
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21
SCHEDULE
The following are the key milestones for implementation of the remedial
acti on:
Approve Remedial Action (exclude ROD)
Initiate Remedial Design
Complete Remedial Design
Initiate Remedial Action (Award Contract)
March 1988
June 1988
June 1989
September 1989
Water main construction and connection of private well users may be
expedited by contracting the design and construction to the City or Eau
Claire's municipal construction contractor.
c
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Attachment A
Enforcement Analysis
No potentially responsible parties (PRPs) had been identified prior to the
completion of the ECMWF RI/FS because the source of the ECMWF contamination
was unknown. A source investigation was conducted during the RI. However.
the source investigation couid ~ot confirm a source or sources and reduced the
pr':;:Jability that the faciiities investigated were the source(s). A potential
source that was not investigated is the National Presto Industries (NPI). The
NPI site is currently on the National Priorities List. NPI entered into an
Administrative Consent Order to jerform a RIfFS at their site, ~hicn is
currently underway.
NPI has owned and operated the NPI site since 1948. Prior to that time the
site was owned by the United States Department of Defense and was operated by
the United States Army as a munitions manufacturing facility.
3ased on the infonnation provided in the RIfFS, it appears :hat past and
present owners and operators of the NPI site are PRPs for the ECMWF site
contamination. It is expected that the NPI RIIFS will provide information
that will confirm or dispute this conclusion. However, to delay PRP
identification until the NPI RI/FS is complete will deny PRPs the opportunity
to participate in the design of the ECMWF site remedial action and inhibit
their opportunity to participate in remedial action implementation.
Ther.ehre. it is expected that these PRPs will be issued a special not.ice
letter in the near future in order to provide them with the opportunity to
perform the remedy.
o
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EAU CLAIRE ~UNICIPAl ~Ell FIELD SITE
EAU CLAIRE, WISCONSIN
RESPONSIVENESS SUMMARY
ihe united States Environmental Protection Agency (U.S. EPA) recently held a
public comment period, March 5, 1988, to March 25, 1988, for interested
parties to comment on the U.S. EPAls March 4, 1988, Feasibility Study (FS) and
Proposed Plan for the final remedy at the Eau Clair~ Municipal '''/ell Field
(ECi,IWF) site.
The purpose of this responsiveness summary is to document U.S. EPAls responses
to comments received during the publ ic comment period. All of the comments
summarized in this document were considered by the U.S. EPA in making its
final decision concerning remedial action at the ECMWF site. Included in this
responsiveness summary, as Attachment A, is a summary af the community
relations activities conducted by U.S. EPA with respect to the site.
I. RESPONSIVENESS SUMMARY OVERVIEW
Recommended Alternative
The feasibility study identified and evaluated alternative remedial actions
for the groundwater contamination at the Eau Claire Municipal Well Field site.
Four elternativ~s were screened and evaluat~d based on the nine criteria
deta.i1ed in the ..Decision SUlTlT1ary. U.S. EPAts reconunendation was Alternative 4
- Onsite Treatment, Discharge, Alternate Water Supply, and Groundwater
Monitoring.
C>
The final groundwater remedy for the site was developed to protect public
health and the environment by preventing ingestion and inhalation of
contaminants found in the groundwater, and by restoring the contaminated
aquifer.
The major components of the selected remedy are as follows:
o Treat contaminated municipal water with an existing air stripper;
"
o Provide municipal water to private well users within or near the
area of groundwater contamination;
o Install groundwater extraction wells in the two plumes of
contamination; and,
o Discharge untreated groundwater from extraction wells to the
Chippewa River.
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2
II. SU*ARY Of COII£KTS ON 11fE FINAL REJ£DY
The following section summarizes written comments received from interested
parties. Many of the comments ~ere edited for clarity or when .multipie
parties made a similar comment.
1.
Comments regarding groundwater extraction.
COlilT1ent:
The City of Eau Claire is concerned with whether the extraction wells
located in Plume 1 will affect the quantity and quality of water in the
municipal wells by lowering the aquifer and by increasing manganese levels
in the municipal wells, because of the possibility that the aquifer will be
further recharged from the river's direction.
u.s. EPA Response:
Two extraction wells are estimated to be pumping at a design discharge rate
of 0.5 million gallons per day (MGO). This extraction rate is relatively
small, compared to the combined extraction rate of the City production
wells in the north well field. Minimal additional impact is anticipated
due to groundwater drawdown from the extraction wells.
Calcu.1ations show that drawdown at a distance of 1000 feet ('the approximate
distance between the location of the proposed extraction wells and pumping
wells 15 and 17) should be less than 5 feet for every 500,000 gallons/day
pumped by the extraction wells. The extraction wells will alter the pattern
of groundwater flow to the municipal well field; and, thus, the amount of
recharge to the well field from various directions will be changed. In
particular, there will be more recharge induced from the Chippewa River. If
the sourcs of elevated manganese is the river, and if the extraction wells
operate long enough, the well field could experience increased levels of
manganese. The shorter the duration of extraction well operation, the less
likely that increased manganese levels will actually be experienced by the
municipal well field.
The remedial design will evaluate the extraction well system in detail.
The exact locations of the extraction wells will be determined to minimize
the possibility of substantial induced inflow of water from the direction
of the Chippewa River, which may increase the level of manganese in the
municipal wells. In addition, the design will evaluate whether additional
treatment at the water plant for manganese may be needed and at what
concentrations. However, it may not be known until the actual
implementation of the remedial action if additional treatment is necessary.
If so, U.S. EPA will address this concern. .
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3
Comment:
The City of Eau Claire is concerned whether the selected alternative will be
successful in Plume l. They have been pumping 4 to 8 MGD from Plume 1 since
1981. dnd vac levels have not changed. The City is also concerned as to what
the 5 year cleanup time is based on.
u.~. :P.A.
qesDonse:
3ased on calculations of groundwater now velocities, the estimated plume
migration travel time for the entirety of Plume 1 to reach the north well
field is nine years. U.S. EPA proposes to install two groundwater extraction
wells located in the north well field to add to the existing five City well~
capacity to extract contaminated groundwater.
ihe 5 year cleanup time is based on the calculated travel times for
groundwater flow in the study area and the locations of the extraction wells
with respect to the distribution of contamination. The municipal well field
has a very broad area of influence - its capture zone includes recharge
induced from the Chippewa River. Thus. only a relatively small fraction of the
pumpage by the municipal well field serves to extract the plume. The
extraction wells have been located and will operate at pumping rates designed
to maximize their effectivene~s for extraction of the contaminants. The
capture zones of the extraction 'well s correspond to the extent of the pl urnes
and near1y all of their pumping will serve'.to extract the pl.umes.
Q
Comment:
The Sierra Club stated that proposed extraction wells have high capacities of
500 HGD and was concerned whether the four extraction wells located in Plumes
1 and 2. operating simultaneously. would leave sufficient water for the City's
needs. In addition. there is a concern whether extraction of this volume
would weaken the overburden.
U.S. EPA Response:
"
U.S. EPA would like to clarify that it is estimated that 0.5 MGO would be
extracted frail! each of the four extraction wells. The outwash aquifer is a
very productive aquifer and it is not anticipated that the volume of water
extracted will impact the volume of water available to the City or affect the
overburden.
"
2.
Comments regarding an unknown source and 5 year cleanup timeframe.
Comments: (Sierra Club. City of Eau Claire, Eder Associates Consulting
Engineers. P.C.. and a local citizen)
o The source or sources of the volatile organic compounds (VOCs) has
not been confirmed or identified.
'J The approx imate amount of pol1 utants is un known.
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4
o How can the lenath of time needed to remove unknown amounts of
VOCs be predicted when the source(s) of pollutants may be actively
contributing to the groundwater pollution?
~ \oJi11 the 1 imited timeframe of 5 years provide a permanent solution?
~ It would seem to be essential to incorporate cleanup of the source(s)
into the proposed remedial action plan.
J The results or the ~Jational' ?resto Industries site are still ~ending,
and the commentor recommends that the results of that study be
incorporated into the well field remedial action plan, if appropriate.
U.S. EPA Response:
U.S. ~PA ~as identified and charac:erized two piumes of contamination at the
ECMWF site, each of which was fully characterized and defined during the RI.
The RI, however, was unable :0 identify dnd confirm a continuous Contributing
source(s) that would adversely affect the cleanup of the groundwater
contamination. The 5 year timeframe is based on the pumping rate of the
extraction wells and plume migration travel times which are estimated from
calculations or groundwater flow velocities. Assuming there is no continuous
source, the estima~ed 5 year timeframe should permanently clean up the
groundwater. However., the remedial action will not be completed until the
target cleanup levels are achieved. .
National Presto Industries: Inc. (NPI) has been .identified as a potential
source. NPI is conducting a RIfFS independent of the ECMWF site
investigation, which will confirm or deny if their site is a continuous
contributing source. If the NPI site is identified as a contributing source
to the groundwater contamination it will be addressed in an independent
remedial action and this potential source will be eliminated.
~
J.
General Comments:
Comment:
A local citizen ;s concerned about discharging the untreated extracted
groundwater to the Chippewa River.
<7
u.S. EPA Response:
The U.S. EPA ~espects this concern and would like to point out that a
Wisconsin Pollution Discharge Elimination System (WPDES) permit will be
obtained which will set limits of contaminants allowed in the discharge. This
should assure that the discharged water will not pose a threat to human health
and the environment. Estimated concentrations of VOCs in the Chippewa River
after discharge and dilution are expected to be below Federal dnd State
Standards.
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5
Conment:
The Sierra Club concurs with the discharge of the untreated groundwater to
the Chippewa River.
U.S. EPA Response:
U.S. EPA appreciates the Sierra Club's acceptance of this component of the
remedy.
CJmment:
The City of Eau Claire questioned whether it would be possible to pump the
water from the north wells to the Chippewa River, running 24 hours per day
at 2 MGD each and provide Eau Claire with additional wells in the south
well field instead.
U.S. E?A Response:
This ~iternative ~as 2valuated in the FS as Alternat~ve 5 whic~ assumed
that both plumes would migrate to the well field and the air stripper would
operate for approximately 40 years. This alternative was dropped from
further consideration because the effectiveness of being able to supplement
the lost water supply by drilling additiona~ wells in the south well field
is unknown. The cost of investigating and installing new production wells,
including associated power costs, would probably offset the costs of .
continued use of tile ai r stri pper .An addi.ti ona 1 factor consi dered i.s that
water from the south well field typically has higher iron and manganese
concentrations that would place additional demands on the existing Eau
Claire water treatment plant.
o
The U.S. EPA further evaluated the proposed alternative from the City
against the use of the air stripper for 9 years, the estimated plume
migration time for Plume 1 to reach the north well field along with the
installation of extraction wells in Plume 2 in order to clean up this olume
concurrent with Plume 1. It was determined that the same reasons mentioned
above apply, including that the additional capital costs associated with
this alternative would probably offset the costs of continued use of the
air stripper, causing this alternative not to be as cost effective as the
reconmended alternative.
"
Corrrnent:
The City of Eau Claire would like to be kept informed on the project,
partic1Jlarly the water main extension, so that they are located and sized
to meet their needs. Areas outside City limits must be annexed before
mains can be extended.
U.S. EPA Response:
The U.S. EPA respects this request and has full intention of working
closely with the City during the remedial design and remedial action. We
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6
are also aware of the need for annexation of adjacent lands, and, again,
anticipate working closely with the City to bring this about.
Corrment:
(Eder Associates Consulting Engineers, P.C.)
The extension of water mains outside the City of Eau Claire limits requires
the annexation of these areas. Individual treatment carbon units were
considered in the selection of the alternative and dismissed because of
"a
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7
u.s. EPA Response:
Groundwater samples were sent to the Zimpro Laboratory in ~othschild,
Wisconsin, for 24 hour turnaround analyses of 29 VOCs utilizing EPA Analytical
1~ethod 624, which does employ confirmatory mass spectrometry.
The following comments are from Eder Associates Consulting Engineers, P.C.
:omment:
The primary concern arising from the Eau Claire RI/FS report is the use of the
computer generated depiction of a water table map presented on Figure 4-21 of
the RI report. According to the text on page 4-73t this water table map was
considered to be "more reoresentative" than the water table map shown in
:=igure 4-22 '",nien, aC:;Jrjing to the legend, is "based oJn actual 7'ield data".
A comparison of the wdter level elevations providea in Appenaix N to the water
level ,:ontours on Figure ~-21 reveals a disc:",epancy of as much as ,Jl:..Js ~O-feet
(:1PI Monitor.;ng l~el1 J). :n ~ac-:, none of the '/late: ;evel ele'lat~ons in :he
eastern portion of the groundwater basin agree with water level contour
elevations.
u.s. EPA Response:
'"
This comment appears to result from a misunderstanding of the purpose of
'Figures 4-21 (computer model water table ma.p) and 4-22 (contoured field data
'Hater table map). Because the distribution of Held data is "not uniform across
the study area, any water table map contoured from the field data cannot fully
depict the shape and configuration of the water tablet and cannot be used to
define the extent of the groundwater basin tributary to the municl0al ~eil
field. On the other hand, because the groundwater model can provide evenly
distributed water elevation estimates, the model is capable of showing the
influence of bedrock topography on the shape and configuration af the water
table, and thus is a "more representative" guide to defining the extent of the
groundwater basin tributary to the well field. The only use of Figure 4-21 is
to define the extent of the groundwater basin tributary. There is no claim
made that Figure 4-21 is an accurate representation of the water table
elevations in the study area. For calculations dependent on actual water table
elevations, such as water table gradientst groundwater flow velocities, or
travel timest Figure 4-22 was used.
<>
I)
Comment:
The groundwater basin boundary depicted on Figure 4-21 does not agree with
Figures 4-2 through 4-8 in the RI report. On Figure 4-21. the boundary passes
through NPI Monitoring Wells 1 and 3t but on Figures 4-2 through 4-8t the
boundary (incorrectly labeled groundwater divide in these figures' legends) is
shown about 1/4 mile west of these wells.
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8
U.S. EPA Response:
The U.S. EPA and its contractor recognize this inconsistency and appreciate
the comment. Please note that the correct position of the groundwater
divide/boundary is shown on Figure 4-21. The ~osition of the groundwater
divide shown in Figures 4-2 through 4-8 is in error.
Comment:
The description of the criteria for the location of Plume 2 as depicted on
Fiaure 4-8 and elsewhere in the reDort is confusina. The second oaraar~Dh
on - Daae 4-18 conta ins the statement: "'rlel 1 s cons is tent j If outs i de the' .
low~si (vaC) contour are...W-S, W-6, W-7, PW04...." 7he~e wells are
located in the western portion of the ~pr property. However, the shaded
area representing Plume 2 on Figure 4-8 encompasses Aells W-5, W-6, W-7,
and PW04. This area s~ould not be included in the shaded area criteria for
plume mapping as stated on page 4-18.
U.S. EPA Response:
The values of the lowest contour lines shown in Figures 4-2 through 4-8
were arbitrarily set at 10% of the maximum concentration detected to allow
visual comparison of the distribution of the various components among the
figures. The extent of each plume, defined to provide for conservative
evaluation of potential risk, was based on actual levels of contaminants
present. The levels of contaminants present in Wells W-5, W-6, W-7, ~nd
PW04 were felt to be significant enough to' include these wells in Plume 2
for the purpose of characterizing that plume for the public health
evaluation.
Comment:
The RIfFS concentrated on four source areas of contamination in the
airport/industrial park area. However, there appears to be little or no
reference to the fact that much of the area is not served by municipal
sewers. The possibility of VOC contamination of groundwater in discrete
pockets caused by septic tanks and dry wells (by cleaning products, for
example) may be a factor in the area. This may account for anomalous VOC
occurrences described in the report as being outside the plume. This
presents the possibility of coincidental occurrence of VOCs within the
plume caused by septic tanks and other sources.
\~.
u.s. EPA Response:
The U.S. E?A is aware of this information and agrees that there may be
multiple sources of the groundwater contamination such as septic tanks and
other. sources within the plumes and outside the plumes. This information
was taken into consideration during the industrial survey and source
investigation.
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9
Comment:
All calculations for pumpage rates and purging times are based on the computer
model which does not appear to be an accurate representation of groundwater
conditions. Also, the 3 inch annual recharge rate useq in the model appears to
be much too low and may have been chosen as a best fit for the model.
u.s. EPA Response:
The calculations for pumpina rates and tr3vel times (on wnich the ourainq
times were based) were not ~ased on the results of the computer model -used to
generate Figure 4-21. These calculations were based on contoured field
data presented in Figure 4-22. The computer code used to calculate capture
zones for the extraction wells was entirely different than that used to
generate Figure 4-21.
Comme~t:
The data interpretation appears to be oiased by the number and location of
monltoring wells. How else could the inclusion of documented areas of private
well contamination be described as a background area (Figure 4-8 of the RI)?
u.s. EPA Response:
u.s. EPA believes that the selection of the number and location of monitoring
wells provides a good representatioR of the bedrock valley in order to
characterize the groundwater contamination'and hydrogeology of the area. The
background wells located across the divide were used to define the limit of
possible flow to the well field. The public health evaluation did not discard
any VOC data as a result of comoarison with background and thus none of the
subsequent conclusions were in any way biased by the characterization of
background water quality presented in the report.
a
Comment:
Eder Associates believes that the U.S. EPA should reconsider the acceptance of
any remedial action selected for the Eau Claire Well Field site with the
exception of providing users of VOC contaminated private wells with an
acceptable and practicable alternative water supply as soon as possible. With
this exception, there ;s no technical basis for ~roceeding with the Remedial
Action Plan and Design until a reevaluation of the RIfFS report and data has
been carried out.
u.s. EPA ~esponse:
Based on the above responses, the U.S. EPA feels that it is appropriate to
procede with the selected remedial action alternative.
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10
COl11Tlent:
According to National Presto Industries, Inc. (NPI), in Section 4,
Paragraph 4.2.6, page 4-58 through the top of page 4-61 of the Remedial
Investigation Report, and in Section 1, Paragraph 1.4.4.3, pages 1-38
through l-~ of the Feasi bil i ty Study, i ncamp 1 ete factual sUlT1T1ar; es are
provided regarding historical use and other informational data regarding
the NPI site. The factual history is incanplete in that it "does not recite
utilization of the site prior to Durchase by NPI and is inaccurate with
respect to factual data regarding use and investigation of the site". A
prooosea revised historical narrative was provided to the U.S. EPA to
supplement these sect1ons.
U.S. EPA Response:
U.S. EPA aopreciates the submittal of the revised historical narrative, ~nd
has inc1uded the document in the ECMWF site administrative record. ~e will
correct any misstated facts in our reports.
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ATTACHMENT A
COMMUNITY RELATIONS ACTIVITIES CONOUCTED
AT THE EAU CLAIRE MUNICIPAL WELL FIELD SITE
Community relations activities conducted at the Eau Claire ."1unicipal Weli
Fie 1 d sit e to d ate i n c i u d e the f 0 1 1 0 wi n g :
o U.S. EPA issued a press release on April 10. 1985. announcing the
availability of a Fact Sheet and the beginning of the Public Comment
Period concerning the Focused Feasibility Study for the Eau Claire
Municipal Well Field site (ECMWF) a The public comment period was to
run from ;~pril 15 to .~ay 6, 1985.
o Two information repositories were established near the ECMWF site on
April 15. 1985.
o Copies of the Fact Sheet were made available on April 15,1985.
o A press conference was held in the afternoon of April 18, 1985.
announcing the status of the project.
Q
o .U.S. EPA officials were available in 'the .evening of Aprfl 18,'.1985 to
answer any questions posed by the Eau Claire residents. Although well
attended by the press, and State and local officials, no other Eau
Claire residents were present.
o The community relations plan was developed in July, 1985.
o A press release on June 13. 1985, announced that UoS. E?A had selected
an Interim Remedial Measure (IRM) for the site.
o Weekly telephone contact with the press was initiated in 1986.
"
o The Fact Sheet for the IRM design phase was released in September,
1986.
o An update to the Fact Sheet was made in August, 1987.
o The administrative record for the ECMWF site ~as established in Marsh,
1988.
o A press release was issued and an advertisement was placed in the Eau
Claire Leader Tele1ram announcing the beginning of the Public Comment
Period on the flna Feasibility Study, in March, 1988.
o The Fact Sheet was updated and the Proposed Plan for remedial action at
che :CMWF site was released on March 5, 1988.
o The public comment period ran from March 5 to March 25, ~988.
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