Agwicy
Rcnwdial RMpons*
Superfund RODR0585016
Record of Decision:
Eau Claire, Wl (IRM)
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TECHNICAL REPORT DATA
(Please read Instruction on the reverse before completing/
1. REPORT NO.
EPA/ROD/R05-85/016
.2.
3. RECIPIENT'S ACCESSION NO.
47TITLE AND SUBTITLE
SUPERFUND RECORD OF DECISION
Eau Claire, WI (IRMJ-
6. REPORT DATE
June 10, 1985
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO
9. PERFORMING ORGANIZATION NAME AND ADDRESS
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
U.S. Environmental Protection Agency
401 M Street, S.W.
Washington, D.C. 20460
13. TYPE OF REPORT AND PERIOD COVERED
Final ROD Report
14. SPONSORING AGENCY CODE
800/00
IB. SUPPLEMENTARY NOTES
16. ABSTRACT
The Eau Claire Municipal Well Field consists of a 500-acre site located in the
northwest corner of the city of Eau Claire, Wisconsin. The Eau Claire municipal
well system supplies drinking water to approximately 57,500 residents and to
numerous commercial and industrial establishments in the city of Eau Claire and the
town of Washington. In March 1981, as part of the U.S. Environmental Protection
Agency Groundwater Supply Survey, the Wisconsin Department of Natural Resources
(WDNR) tested the Eau Claire municipal water supply for volatile organic compounds.
The following organic compounds were identified in the municipal water supply:
1,1-dichloroethene, 1,1-dichloroethane, 1,1,1-trichloroethane, and trichloroethene.
The selected remedial action includes construction of air stripping facilities
to remove volatile organic compounds from the contaminated flow (14 million gallons
per day (mgd)) from the north well field. The treated water will be discharged into
the municipal water treatment plant and distribution system. Total capital cost for
the selected remedial alternative is estimated to be $1,420,000 with O&M costs
estimated to be an additional $195,000 per,year.
17. KEY WORDS AND DOCUMENT ANALYSIS
t. DESCRIPTORS
Record of Decision
Eau Claire, WI
Contaminated Media: gw
Key contaminants: VOCs, 1,1,1-Trichloroe-
thane, 1,1-Dichloroethene, Trichloroethene,
Tetrachloroethene and 1,1-Dichloroethane
IS. DISTRIBUTION STATEMENT
b. IDENTIFIERS/OPEN ENDED TERMS
None
20 SECURITY CLASS iTIiis pu.ei';
None
c. COSATI lield.Cr. •...-
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21. NO. OF PAGES
35 i
22. PRICE J
1
P*rm 2220-1 ((<•«• 4-77) PMIVIOUS EDITION is OBSOLETE
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""POfIMING ORGANIZATION CODE
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AUTHOR.II
Gift 88me(s) in con"cntional order (John R. Doe, J, Robe'" /Jot'. ('Ic'.),
zalion.
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Include a brief (ZOO MIOI'ds eN IIrs) factual summary of the mosl si"nllkant Infurm"tllln ~un!"In~'II III ,".' "'1'1111. II III,' "'1'"11 ""11.1111' ~
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17. KEY WORDS AND DOCUMENT ANAL VSIS
(a) DESCRIPTORS. Selcct from the The'aurus of Englneerir.If ,Uld S~"'IIIIII' /"'111' Ih" prup'" ~u'""",,.J 1..,,,,, Ih~II~Io:IIIII~ III., m.II'"
concept of the reseah:h and art sufficienlly )pcclfic anll pred,c 10 bc u,,,..1 ~, m..ln cnlllC' lur '~I"I..~IO~.
(b) IDENTII'IERS A~D oprS.I:SDED TERMS. L:se Idenllfieh for prolcd n~III". ,ulle n~m",. cljulp",,,nl ,,,""en.,',,r,. ,'I<: l,,' "".'11.
ended lerms Wllllen In dC)CflplOr form for those ~ubJects for which no J"'Llll'lur ",.,1\,
(c) COSA TI nI-:LD GROUP. '"ield and Jfoup assilnments olre 10 be t"k,'n frum the I ~f1S (,OSI\ II Suh,.,.:! (.~ Iq!\lIY Usl. Sinn' thc 01..'
jOlity of documenl\ are multidisciplinary in nature, Ihe Prim:ary I.eld', (;roup ""IA!nmcntf 'I W III be '!In III' III" Il'lIn,'. ar,'a III hUIII.,n
endeavor. or type of physi.:al object. The :apphcalionls) will be: cross.relcrcnced with 'c.."nllar~ 11..111 '( ,rulli' ~"'j:nl11,'n" th.11 \\ III '..I!,.\\
the primary posling!s),
,.. DISTRIBUTION STATEMENT
Denole relcasabilit). to the public or linlllallon for reil'ons uthcr th"n ,,:~ulIl~ IUI "'''011'10: "K,."'"". I III""IIL.'I." III.. ~II~ ,...111.,1'0111\ '..
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22. PAICE
Insert the pril.:e srI by the National fed:nICallnformalion SLI\"" lOr Ih, C;u'crnlll""t I'lmling Olfi~c, I' knlJ\\n
I PA 'er.. 2220-1 (Rev. .-77) (R.v.,..)
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Record of Decision
Initial Remedial Alternative Selection
Site Eau Claire Municipal Well Field
---- Eau Claire County, Wisconsin
Documents Reviewed
This decision is based on the following documents describing the analysis. -
of cost-effectiveness of remedial alternatives for the Eau Claire-Municipal
Well Field:
- Focused Feasibility Study, Eau Claire Municipal Well Field,
Eau Claire, Wisconsin. CH2M Hill, April 11, 1985, Attachments
1 and 2
- Summary of Remedial Alternative Selection
- Responsiveness Summary
- Memorandum from Steve Rothblatt. Chief, Air and Radiation
Branch to Richard Bartelt, Chief, Emergency and Remedial
Response Branch
- MemoranduM from Joseph Harrison, Chief, Safe Drinking Water
Branch to Richard Bartelt, Chief, Emergency and Remedial
Response Branch
- Memorandum from Robert B. Schaefer, Regional Counsel and
B. G. Constantelos, Director, Waste Management Division
to Valdas V. Adamkus, Regional Administrator
- Letters from C.D. Besadny, Secretary, Wisconsin Department
of Natural Resources to Valdas V. Adamkus, Regional
Administrator
- Preliminary Hydrogeologic Evaluation, Eau Claire Municipal
. Well Field, Eau Claire. Wisconsin, CH2M Hil', April 1985
- Report on Water Treatability - City of Eau Claire, Strand
Associates, Inc., May 1984
Description of Selected Remedy
Construct air stripping facilities to remove volatile organic compounds
from the contaminated flow (14 million gallons per day [mgd]) from the
north well field. The treated water will be discharged into the municipal
water treatment plant and distribution system.
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Declarations
Consistent with the Comprehensive Environmental Response Compensation and
Liability Act of 1980, and the National Contingency Plan (40 CFR Part 300).
I have determined that construction of air stripping facilities to treat
contaminated water for municipal water system treatment and distribution is
a cost-effective initial remedial measure and provides adequate protection
of pUblic health, welfare, and the environment. The State of Wisconsin has
been consulted and agrees with the approved remedy. In addition, the action
will require future operation and matntenance activities to ensure the
continued effectiveness of the remedy. These activities will be considered
part of the approved action and eligible for Trust Fund monies for a period
not to exceed 1 year.
It has also been determined that the action being taken is consistent with
permanent remedy at the site, and is appropriate when balanced against the
availability of Trust Fund monies for use at other sites.
The U.S. Environmental Protection'Agency is continuing its remedial inves-
tigation/feasibility study (RI/FS) of the Eau Claire Municipal Well Field
to evaluate potential sources of contamination and the hydraulic charac-
teristics of the aquifer in order to evaluate potential remedial actions.
If additional remedial action(s) are determined to be necessary. a Record
of Decision will be prepared for approval of the future remedial action(s).
~t;
Date
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Narrative Summary
.1
Site Location and Description
The City of Eau Claire is located in northwest Eau Claire County, Wisconsin
at the confluence of the Eau Claire River and the Chippewa River. At
present, the City water system is supplied by groundwater. The municipal
welJ field, a 500-acre site, is located in the northwest corner of the City
on the east bank of the Chippewa River near the Eau Claire County airport.
(Figure 1) The Eau Claire municipal well system supplies drinking water
to approximately 57,500 residents and to numerous commercial and industrial
establishments in the City of Eau Claire and the Town of Washington. Land.
use in the vicinity of the well field consists of light industry east of
the airport and residential areas to the east and south of the well field.
The City-owned water system includes 14 active wells, a water treatment
facility, and three ground level storage reservoirs.
The two important aquifers in the Eau Claire area are the alluvial sand and
gravel deposit and the underlying sandstone deposit. The alluvium is a
more important source of water than the sandstone. The alluvium holds a
higher quantity of water, and, in the area of the municipal well field, is
a significantly more substantial deposit than the sandstone.
The two aquifers,. although adjacent, are not considered hydraulically con-
nected. The hydraulic conductivity of the sandstone is estimated to be
about three orders of magnitude lower than the sand and gravel deposits.
The sandstone is not considered a viable water source because of its low
productivity. The'city wells draw from the sand and gravel aquifer. There
is no other isolated uncontaminated aquifer available as a potential drink-
ing water supply in the Municipal well field area.
Sources of natural recharge to the aquifers are local precipitation and
infiltration of flood waters along river terraces. In addition, the
Chippewa River is a source of groundwater recharge for the municipal well
field.
SHe Hi story
In March of 1981, as part 6f 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 volatile organic
compounds (VOCs).
The following four organic compounds were identified in the municipal water
supply: l,l-dichloroethene, l,1-dichloroethane, l,l,l-trichloroethane, and
trichloroethene. The WDNR 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 DNR district office conducted
additi.onal testing in January 1982 on 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 (Well Nos. 11 and 15) exceeded
Wisconsin health advisories for potable water supplies for l,l-dichloro-
ethene. However, due to the blending with the other wells, the contamina-
tion in the finished water was below the health advisories.
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Concerned for the future use of the water supply, the City retained E.A.
Hickok and Associates in May 1982 to conduct a hydrogeological well field
study identifying the quantity and quality of water expected for the next
20 years. In September 1982, the City requested that Hickok and Associates
conduct additional hydrogeological testing to identify the source and
extent of VOC contamination in the well field. In addition, Strand
Associates, Inc., was retained to evaluate various treat~ent alternatives
for the removal of VOCs and options to improve iron and manganese removal.
Concurrently, the City also upgraded laboratory equipment to provide capa-
bilities for VOC analyses for monitoring of municipal and residential
wells.
With the new laboratory equipment, the City began testing private .residential
wells, in addition to monitoring the municipal production wells. Residential
wells located on the north side of Eau Claire and in Town of Hallie, located
immediately northwest of Eau Claire, were sampled to gather background infor-
mation defining the extent and to assist in identifying potential sources
of the VOC contamination. Several residential wells reported detectable
levels of VOCs.
As a result of the residential well sampling, the City informed Mr. Donald
Hillnan that samples collected from his well on January 12, 1983, indicated
a 1,I-dichloroethene concentration in excess of the WDNR health advisory
level. The City advised Mr. Hillman not to use his water supply for
drinking. Mr. Hillman1s well is upgradient of the municipal well field in
the suspected path of groundwater flow.
,
By Spring of 1983, IDNR had nominated the municipal well field as a potential
Superfund site. On September 11, 1984, the Eau Claire Municipal Well Field
was included on the Superfund National Priorities List. The Eau Claire site
was given a high priority by the WDNR because it affects a large population
and because the contaminants have a high toxicity and persistence 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 VOC 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 indicate that this ~ilot system successfully removes VOCs from the
water supply.
In addition to monitoring the private residential and Municipal production
wells, the DNR began to investigate the potential sources of groundwater
contamination in Eau Claire. In the Summer of 1984, DNR representatives
investigated VOC handling of 22 commercial establishments by inspecting the
facilities and interviewing the owners. Of these, the DNR identified nine
that it determined were potential sources of contamination based on
operational information developed through the investigation.
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Since the original March 1981 sampling, the following organic compounds
have also been detected in the municipal well field and/or residential
wells in the area by the City of Eau Claire and/or U.S. EPA: tetrach10ro-
ethene, 1,2-dich10roethene, and 1,2-dich10roethane. The compounds
1,2-dichloroethene and 1,2-dich10roethane have been detected at low or
trace levels in the well field. The highest detected concentration of
tetrach10roethene detected in the well field is listed below.
The U.S. EPA began its remedial investigation (RI) in January, 1985.
work should be fully underway in Summer, 1985.
As part of the RI, U.S. EPA contractors conducted a Preliminary Hydrogeologic
Evaluation. The report evaluates and summarizes available data for the Eau
Claire area, focusing on the geology, groundwater hydrology, and climatic
conditions. The report suggests that a~ alluvial bedrock channel runs
through the Eau Claire area, and the contaminant plume may be following the
channel, moving north and west towards the Chippewa River. Data collected
thus far shows a pattern of VOC contamination along this bedrock channel
( F i gu re 2).
Field
Current Site Status
The highest concentrations of those organic compounds frequently detected
on or near the site are:
1,1,1 - Trichloroethane
1,1 - Dichloroethene
Trich1oroethene
Tetrachloroethene
1,1 - Dichloroethane
- 188 ug!l
- 20 ug/l
- 34.6 ug/l
17.1 ug/l
10.3 ug/l
These concentrations of contaminants were detected in test wells in the
municipal well field.
Contaminated wells appear to be confined to two areas. Municipal wells 11,
15, 16, and 17 in the northern part of the municipal well field, and two
private wells (D. and J. Hillman), have shown the highest levels of VOC
contamination. The other mpin area of groundwater contamination is approxi-
mately two and one half miTes west of the municipal well field, and several
wells up to one half mile to the north of that area. The contaminated
wells are generally limited to areas of thickest alluvium.
Toxicity of Pollutants
Three of the identified compounds at the Eau Claire site (1,1-dich10roethene,
trichloroethene, and tetrachloroethene) are suspected human carcinogens.
The Safe Drinking Water Act establishes Recommended Maximum Contaminant ..
Levels (RMCLs) for non-threshold toxicants such as carcinogens to be zero.
RMCLs are health goals, not regulatory limit requirements.
The U.S. EPA Cancer Assessment Group (CAG) has established cancer risk
levels for the suspected carcinogens found at Eau Claire. The 1 x 10-6
cancer risk levels, as established by the U.S. EPA CAG, are listed below
for these compounds.
~.- . --...,~..- -'-::~.:o-:..t':"
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l.l-Dichloroethene
Trichloroethene
Tetrachloroethene
0.19 ug/l
1.5 ug/l
0.82 ug/l
The 10-6 cancer risk level represents the estimated contaminant concentra-
tion in drinking water which would result in an additional incident of
cancer per million people. The cancer risk levels assume ingestion of two
liters per day of drinking water for 70 years. Drinking water is considered
acceptable for consumption if it does not exceed the 10-6 cancer risk
level.
It can be seen that the concentrations of l.l-dichloroethene. trichloro-
ethene. and tetrachloroethene have been detected at concentrations more
than an order of magnitude greater than the 10-6 cancer risk level. or more
than the 10-5 cancer risk level.
Threat to Public Health
The contaminants in the groundwater at the Eau Claire site present a threat
to the public health. Approximately 57.000 people are potentially affected.
The public is exposed to the contaminants (discussed above) from the treated
and distributed groundwater. There are three primary exposure routes:
ingestion of water. dermal absorption from bathing. and inhalation of
vapors released from the water during bathing and other uses.
The contaminants present at Eau Claire are chlorinated compounds. Chlori-
nated compounds are/irritants to the eyes and/or mucous membranes. They
are highly or moderately toxic via oral (drinking water) and/or inhalation
routes. Of the above three primary exposure routes due to contaminated tap
water. current knowledge and data limit a quantitative risk estimation to
. a calculated cancer risk estimation due to ingestion only.
The Agency prepared an endangerment assessment in the Focused Feasibility
Study (FFS) for the Eau Claire site (Chapter 4). The purpose of the
endangerment assessment was to estimate the risk posed by the suspected
human carcinogens. 1.I-dichloroethene. trichloroethene. and tetrachloro-
ethene. This calculated risk does not account for the risk associated with
the compounds not identifi~ as suspected carcinogens (l.l.l-trichloroethane
and l,l-dichloroethane) and, 1n this sense, may be an underestimate.
Both current and future health risk assessments were prepared. The current
health risk assessment was calculated for two different conditions:
a) finished water - mean contaminant concentration. and b) finished water-
maximuM contaminant concentration. The calculation for finished water-mean
contaminant concentration represents the risk assessment if the current
output of the municipal water supply and treatment system is continued. '
The risk assessment for the maximum contaminant concentration presents a
risk based on ingestion of maximu~ contaminant concentrations observed in
the finished water.
At the time of the FFS. the Eau Claire finished municipal water had not been
tested for tetrachloroethene. Therefore. tetrachloroethene could not be
accounted for in this part of the risk assessment. Tetrachloroethene has
been detected in test wells in the municipal well field and may be present
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in the finished municipal water. The total present risk presented may be
an underestimate due to lack of information about tetrachloroethene in the
finished municipal water.
The future health" risk was calculated for two different conditions:
a) fut~re finished water assuming complete contamination of the north well
field and, b) future finished water assuming complete contamination of the
north well field and a 25 percent increase in contaminant concentration.
The concentrations of contaminants in "future finished water assuming com-
plete contamination of the north well field" were deterl!lined by assuming:
. 1) the nine north well field wells were contaminated at the maximum conta-
minant concentrations ever detected in the north well field and ~he entire
south well field was contaminated at the maximum contaminant concentration
ever detected in the south well field, and 2) the water from both well
fields was blended in a proportion as typical of past practices.
Table 1 summarizes the calculated health risks calculated in the FFS
endangerment assessment.
As presented in Table 1, the current health risk for drinking Eau Claire
city water approaches, and likely exceeds, the 10-5 cancer risk level. (The
10-5 cancer risk level represents the estimated contaminant concentration
in drinking water which would result in an additional incident of cancer per
100,000 people.) Furthermore, future health risk assessments indicate that
if the Eau Claire Well Field continues to worsen in contamination, the
public health ris~ will further increase.
Pursuant to Agency Policy the 10-5 cancer risk level for drinking water is
the action level for initial remedial measure implementation. At this
level of contamination, the threat to pUblic health is considered great
enough to warrant taking initial measures before final remedial measure(s)
are implemented.
Alternatives Evaluated
The National Contingency Plan states that initial remedial measures (IRM)
can and should begin if s~ch measures are determined to be feasible and
necessary to limit exposure or threat of exposure to a significant health
or environment hazard, and if such measures are cost-effective [40 CFR
300.68(e)(1)]. Pursuant to Agency policy, the IRM should also be compatible
with any long-term remedial measure that may be developed at a later date.
The primary objective of the Eau Claire IRM is to protect public health by
providing a reliable supply of safe, potable water to those consumers
currently dependent on the Eau Claire Municipal Well Field. The long-term
remedial measure(s) will likely provide for cleanup of the groundwater in
the municipal well field. The selected remedy achieves the primary objective
and works towards the likely final remedial measure(s).
Fifteen alternatives were examined as potential IRMs at Eau Claire. They
were evaluated in terms of their ability to protect public health and their
technical feasibility/implementability. If either one of these criteria
would not be met to at least a moderate degree, the alternative was elimi-
nated from further consideration. Table 2 summarizes the screening proce-
dure. The following alternatives were advanced to further screening: well
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Table 1 - Risk Assessment Summary
Finished Water - Tetrachloroethene
Mean Contaminant Trichloroethene 2 x 10-6
Concentrations 1,1-Dichloroethene 5 x 10-6
Total 7 x 10-6
Fi nished Water - Tetrachloroethena
Maximum Contaminant Trichloroethene 3 x 10-6
Concentration 1,1-Dichloroethene 8 x 10-6
Total 11 x 10-6
(1 x 10-5)
Finish Water - Tetrachloroethene 10 x 10-6
Complete Contamination Trichloroethene 10 x 10-6
of North Well Field 1,1-Dichloroethene 60 x 10-6
Total 80 x 10-6
(8 x 10-5)
Finished Water - Tetrachloroethene 10 x 10-6
Complete Contamination Trichloroethene 20 x 10-6
of North Well Field 1,1-Dichloroethene 70 x 10-6
and a 25 percent 100 x 10-6
increase in contaminant Total
concent rat ion (1 x 10-4)
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Table 2
PRIMARY SCREENING
PUBLIC HEALTH AND TECHNICAL FEASIBILITY C~ITERIA
Initial Alternatives
No action
Well field management
Air stripping of contaminated wells
using packed tower aeration
Air stripping of contaminated wells
using diffused aeration
Granular activated carbon treatment
of contaminated wells
Chemical treatment of contaminated wells
Reverse osmosis treatment of contaminated
we 11 s
Ion exchange treatment of contaminated
we 11 s
Steam stripping of contaminated wells
Biological treatment of contaminated
we 115
Abi 1 i ty to. Technical
Protect Feas i bil ity/
Pub 11 c Hea lth .!!!!J!.l ementabi 1 i ty
Poor NA
Moderate Moderate
Good Good
Good Good
Good Good
Poor Poor
Poor Poor
Poor
Poor
Good
Good
Poor
Poor
Cormaents
No increase in protection of public
health without some action
Advanced to secondary screening
Advanced to secondary screening
Advanced to secondary screening
Advanced to secondary screening
Eliminated; not effective in
" removing organics
El imi nated; imperfect wi th respect
to organic separations, concentrate
stream developed and pretreabQent
requi rement
Eliminated; not effective in
removing organics
Advanced to secondary screening
Eliminated; bacteria ineffective in
removing organics present. removal
of organics to concentrations
required impractical
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Table 2 (Continued)
Initial Alternatives
Ability to
Protect
Public Health
Technical
Feasibility/
Implementabllity
Comments
Connect to another water system
Drill new wells
Deepen existing wells
Bulk water delivery and storage
River water intake
NA-Not Applicable
Good
Poor
Moderate
Moderate
Moderate
Good
Good
Poor
Poor
Good
Eliminated; no other water system
available
Advanced to secondary screening
Eliminated; no lower, isolated
aquifer available
Eliminated; not practical for meet-
ing water system requirements
Advanced to secondary screening
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field management, air stripping of contaminated wells using packed tower
aeration, air stripping of contaminated wells using diffused aeration, gran-
ulated activated carbon treatment of contaminated wells, steam stripping of
contaminated wells, drill new wells, and river water intake.
Table 3 outlines initial alternatives advanced for further screening and
the criteria upon which they were evaluated. In addition to ability to
protect public health and technical feasibility/implementability, these
alternatives were subject to the following screening criteria: compati-
bility with further remedial measures, relative costs, environmental
effects, reliability, time required to implement, and community impacts.
The following alternatives were advanced for detailed analysis and further
screening: well field management, air stripping of contaminated wells
using packed tower aeration, and drill new wells. The three alternatives
advanced for further screening were developed into potential IRM
alternatives.
Alternative 1.
Well Field Management/No Treatment
Alternative 1 strictly utilizes well field management techniques to meet
the objectives of the IRM. In this alternative a barrier is created to
prevent contaminated groundwater from migrating into the uncontaminated
areas of the well field. The barrier is created using blocking wells and
the existing contaminated production wells. New production wells would be
constructed to replace system capacity lost when the existing conta~inated
production wells were committed to plume control. Contaminated water pu~ped
from the blocking wells and the four contaminated production wells would be
discharged directly to the Chippewa River without treatment.
Alternative 2.
Well Field Management/Treatment
Alternative 2 incorporates aspects of both the well field management and
the treatment alternatives.
Alternative 2 involves using blocking wells and the existing contaminated
wells to adjust the hydraulic gradient of the groundwater table and effec-
tively protect the uncontaminated areas of the well field. Contaminated
groundwater removed by the/blocking wells would be discharged to the
Chippewa River. Groundwater removed by the contaminated production wells,
however, would be treated by air stripping to remove the vacs and subse-
quently discharged into the municipal water treatment and distribution
system. The air stripping system would provide capabilities for stripping
5.7 mgd of contaminated groundwater.
The aeration treatment system would be designed to achieve 99.6% removal of
the critical contaminant 1,1-dichloroethene. (The contaminant l,l-dichloro-
ethene is designated the critical contaminant because it is the most diffi-
cult, of the contaminants present at Eau Claire, to treat with the air
stripping technology.) This removal efficiency would provide finished water
at less than a cumulative 1 x 10-6 excess lifetime cancer risk. The syste1n
would be designed to treat water within influent volatile organic concentra-
tions of 1.25 times the maximum reported concentration in any production
well or test well found in the north well field.
. n... .-... -. .." .
-------
Table 3 SEI. tV SC~EENING
Tech-
nical
Abil ity Feasi- Time
Protect * bil ity/ Environ- Requi red Com-
Initial Public. Compati- Implemen- Re lat i ve mental Relia- to munity Conclusion of
Alternatives Health !>ility taM 1J!l Costs Effects bi lJ.!lJ!!!P-l ernent Impacts Initial Screening
-- - ----
Well field management Moderate Good Moderate Moderate Low High 1-6 mos. low Advanced to detailed
analysis
Air stripping of con- Good Good Good Moderate r~oderate High 3-6 mos. low Advanced to detailed
taminated wells using to analysis
eked tower aeration High
Air stripping of con- Good Good Good High Moderate High 3-6 mos. low Eliminated; comparable
taminated wells using to stripping with a
diffused aeration packed tower except
more costly
Granular activated Good Good Good High to r~oderate High 2-3 mos. low El imi nated; very
carbon treatment of Very costly for quantity of
contaminated wells High water that must be
treated
......
Steam stripping of Good Good Good High Moderate High 3-6 mos. low Eliminated; comparable
contaminated wells to stripping with a
packed tower except
-'. more costly
ill new well s Moderate Good Good Moderate Low IHgh 2-3 mos. low Incorporated with well
field management
alternative and
advanced
River water intake Good Poor Good Very High Moderate High >1 year low E11mi nated; very
costly, long implemen-
tation, inconsistent
with ultimate remedial
action
*Compatibility with further remedial measures which may be implemented at a further date.
-------
-11-
Alternative 3.
Treatment
Alternative 3 would provide treatment for the contaminated groundwater
supplied by the north well field (14 mgd).
Alternative 3 involves providing air stripping facilities to remove vacs
from the contaminated flow from the north well field (14 mgd). Since
blocking wells are not part of this alternative, the plume of conta~ina-
tion may migrate, thus contaminating the remaining north well field. The
facilities will be sized to strip sufficient water to meet water system
re~uirements when coupled with the remaining uncontaminated wells assuming
contamination of the entire north well field. The air stripped water would
be discharged into the municipal water treatment plant and distribution.
system. . No discharge of contaminated water to the river would be' necessary.
As in Alternative 2, the aeration treatment system would be designed to
achieve 99.6~ removal of the critical contaminant l,l-dichloroethene.
(The contaminant l,l-dichloroethene is designated the critical contaminant
because tt is the most difficult, of the contaminants present at Eau Claire,
to treat with the air stripping technology.) This removal efficiency would
provide finished water at less than a cumulative 1 x 10-6 excess lifetime
cancer risk. The system would be designed to treat water with influent
volatile organic concentrations of 1.25 times the maximun reported concen-
tration in any production well or test well found in the north well field.
Seler.tion Process
The three developed. alternatives identified above, along with the no action
alternative were further evaluated, in accordance with the NCP. (See Table
4, for a costs summary of the three developed alternatives, includTng
present worth cost estimates.) Pursuant to the NCP, the Agency evaluated
the remedies to determine the appropriate cost-effective remedy.
During the early stages of the alternatives review, the no action alter-
native was eliminated from further consideration. In part, the decision
was based upon an evaluation of the health risks posed by the presence of
vacs in the Eau Claire drinking water and a recognition of the unlikelihood
of a natural reduction in the amounts of these compounds in the city water.
I
Until the remedial investigation for the Eau Claire site is completed, the
complete nature and extent of the contamination of the well field is unknown.
The implementation of an appropriate IRM will minimize and mitigate the con-
tamination of the Eau Claire water supply system and reduce the associated
health threat to those dependent on the water supply system. Without the
implementation of an initial measure, the users of the system are exposed
to an unacceptable health risk. (See discussion of health risks in Threat
to Public Health section above.) Therefore, the no action alternative is not
appropriate.
The remaining three alternatives are relatively comparable in terms of the
screening criteria used to select the appropriate IRM for the Eau Claire
site. Table 5 summarizes the screening criteria comparison of the three
developed alternatives. Nine criteria were used in this comparison. Each
alternative was screened in terms of: ability to protect publi, health,
compatibility with final remedial measures, technical feasibility and
-------
-12-
TABLE 4 --- COSTS SUMMARY
Alternat i ve 1 Alternative 2 Alternative 3
Capital Costs $1,550,000 $1,780,000 $1,420,000
Annual O&M $95,300 $133,000 $195,000
5 yr Present Worth $1,911,000 $2,284,000 $2,160,000
Present Worth Index 1.00 1.20 1.13
-------
-13-
'I
implementability. relative economic costs. environmental effects. aesthetics.
reliability. time of implementation. and community impacts. The ability to
protect the public health is the criterion of primary importance.
Alternative 3 is superior to Alternatives 1 and 2 in terms of public health
protection. Alternatives 1 and 2 incorporate the use of a system of block-
ing wells to prevent the plume of contamination from migrating further into
the well field. Blocking well systems are used in similar situations and
are considered a capable technology. These systems are. however. difficult
to implement because of uncertainties in subsurface geology. The air strip-
per required in Alternative 3 is easily implemented because it is a we11-
known. fully man-made system. Success of the air stripper is not dependent
on a good understanding of the subsurface geology. The easy imp1ementability
and high expectations for successful operation of Alternative 3 reflects it
as better than Alternatives 1 and 2 for public health protection.
In terms of economic cost. all three alternatives are within 20 percent of
each other. As such. this screening criteria does not indicate a preference
for any given alternative.
The other screening criteria do not identify any significant differences
between the three alternatives. No significant environmental effects or
community impacts are expected from any alternative. All three alterna-
tives should be able to be implemented quickly enough to meet 1986 Summer
water demands. The major components that make up the three alternatives
are considered highly reliable. All three alternatives work towards the
likely final remedial measure of restoration of the groundwater in the
area of the municipal well field. The slight differences with respect
to these screening criteria are outlined in Table 5.
Community Relations
The Superfund activities at the Eau Claire Municipal Well Field site have
been followed closely and consistently by the local press. Interest in
Superfund activities has been high. News accounts of the activities
have been accurate. The public in Eau Claire has indicated that they feel
that all officials involved (city. city-county. state. and federal) have
responded promptly and properly to the groundwater contamination.
I
Copies of the FFS were made available to the community on April 15. 1985.
The Eau Claire City Hall and Eau Claire Public Library served as reposi-
tories. The U.S. EPA issued a press release on April 10. 1985. which
announced the April 15 availability of the study of the April 15 - May 6
public comment period. The press release announced a U.S. EPA press con-
ference which was held in Eau Claire City Hall on the afternoon of
April 18. 1985. and a U.S. EPA question and answer session about the pro-
ject on the evening of April 18. 1985.
The press conference was well-attended by the local newspaper. television.
and radio stations. Coverage of the U.S. EPA news releases by the press
was extensive. The evening question and answer session was attended only
by State and City officials. the press. and one local industry representa-
tive. No other Eau Claire residents attended the session.
... '''.''"79~~'''"r:
-------
TablE
- EVAlUATIO.
Alternative Identification
Alternative 1
Well Field Management
- Five (5) new blocking wells
Continuous pumping of four (4)
existing contaminated wells
Three (3) new production wells
Criteria
Ability to Protect Public Health Dependent on limiting migration
of contaminants
If north well field becomes
contaminated, 9.0 mgd of
safe water could be delivered
by the municipal well fielda
Compatibility with Final
Remedial Measures*
Proposes to limit spread of
contaminants into well fiel~.
Proposes to discharge approxi-
mately 10 mgd of contaminated
groundwater into the Chippewa
River
No provisions for treatment of
contaminated groundwater
.,1ARY
Alternative 2
'.
,
r-
i'
t -
l"
!
!
Alternative 3
Well Field Managentent/Treatment Treatment
Five (5) new blocking wells
Continuous pumping of four (4)
existing contaminated wells
Air stripping system in the
north well field for 5.7 mgd
Dependent on limiting migration
of contaminants
If north well field becomes
contaminated, 14.7 mgd of
safe water could be delivered
by the municipal well fielda
and treatment system
Proposes to limit spread of
contaminants into wel1 field
Proposes to discharge approxi-
mately 4.3 mgd of contaminated
groundwater into the Chippewa
River -
Provisions for treatment of
5.7 mgd of contaminated
groundwater
* Final remedial measures will likely provide for cleanup of the aquifer in the city wel1 field.
Air stripping at the
water treatment plant
for 14 mgd
If north well field
becomes contaminated,
23 mgd of safe water
could be delivered
by the municipal well
fielda and treatment
system
Allows for possibility
of migration of con-
taminants into
slightly contaminated
and uncontaminated
areas of well field
No provisions for dis-
charge of contaminated
groundwater into the.
Chippewa River
Provisions for treat-
ment of 14 mgd of con-
ta.inated groundwater
-------
Criteria
Technical Feasibility and
Imp1ementabi1ity
Relative Costs
Present Worth b,c
Present Worth Index
Environmental Effects
Water Quality
-15-
Alternative 1
--
Proven, capable technology
Variability in subsurface
. condi t ions make des i gn of
blocking well barrier
difficult
Permit required for discharge
of contaminated groundwater
to Chippewa River
Acquisition of easements may
be re4uired if part of the
blocking well barrier is
located on private property
$1 ,911 ,000
1.00
No significant water quality
impact as a result of dis-
charging approximately 10 mgd
of contaminated groundwater
to the Chippewa River
Alternat ive 2
Proven, capable technologies.
Variability in subsurface
conditions makes design of
blocking well barrier
difficult
Site specific pilot data on
the air stripping process
may help optimize stripping
tower design
Permit required for discharge
of contaminated groundwater
to Chippewa River
Air emissions discharge
permit not required
Acquisition of easements may
be required if p~rt of the
blocking well barrier is
located on private property
$2,284,000
1.20
No significant water quality
impact as a result of dis-
charging approximately 4.25
mgd of contaminated ground-
water to the Chippewa River
Alternative 3
Proven, capable tech-
nology
Air stripper is a well
known, easily control-
able technology
Site specific pilot
data on the air strip-
ping process may help
optimize stripping
tower design
No river discharge
permit requi red
Air emissions dis-
charge permit not
required
No acquisition of
easements required
$2,160,000
1.13
No water quality im-
pact; no discharge of
contaminated water
-------
-16
-.Criteria
Alternative 1
Alternative 2
Alternative 3
Air Emissions
No impact on air quality, no
stripping of VOC's required
Aesthetics
Water Quality
Visual
Potential degradation of raw
water quality due to increased
iron and manganese concentra-
tions due to potential changes
in aquifer hydraulic charac-"
teristics as a result of in-
stallation of blocking well
system
Minor short-term impact re-
lating to construction of new
wells and water discharge
piping
Future organic air emissions
conservatively estimated at
5.34 Ibs/day
Total influent organic load
(Ibs/day) would have to in-
crease approximately thirteen
fold above current conditions
before air emissions control
would be required
Extremely remote possibility
that organic emissions would
exceed 15 Ibs/day, necessi-
tating air emissions control
Potential degradation of raw
water quality due to increased
iron and manganese concentra-
tions due to potential changes
in aquifer hydraulic charac-
teristics as a result of in-
stallation of blocking well
system
Minor short-term impact re-
lating to construction of new
wells, discharge piping, and
air stripping system
Future organic air
emissions conserva-
tively estimated at
13.09 Ibs/day
Total influent orga-
nic load (Ibs/day)
would have to increase
approximately nine
fold above current
conditions before air
emissions control
would be required
Remote possibility
that organic emissions
would exceed 15 Ibs/
day, necessitating air
emissions control
Insignificant short-
and long-term impact
relating to siting of
air stripping system
at water treatment
plant
-------
-17-
Criteria
Reliability
Time Required to Implement
Community Impacts
Alternative ±
No significant long-term
impact
High reliability, provides
20.3 mgd of safe water with
one production well out of
service
Ample time to implement to
meet 1986 summer water
demands that approach maxi-
mum daily demand
28-38 weeks from initiation
of design to system startup
No adverse community impacts
Alternative 2
Minor long-term impact re-
lating to siting of air
stripping system in park
setting of the municipal well
field
High reliability, provides
19.2 mgd of safe water with
one stripping tower out of
service
Ample time to implement to
meet 1986 summer water
demands that approach maxi-
mum daily demand
35-42 weeks from initiation
of design to system startup
No adverse community Impacts
Alternative 3
High reliability, pro-
vides 18.0 mgd of safe
water with one strip-
ping tower out of
service
Ample time to imple-
ment 1986 summer water
demands that approach
maximum daily demand
33-42 weeks from
initiation of design
to system startup
No adverse community
impacts
aAssumes uncontaminated wells outside of north well field would remain uncontaminated.
DBased on using five blocking wells to create barrier in contaminant plume.
*esent worths for Alternatives 1, 2, and 3 are $2,131,000, $2,468,000, and $2,160,000 respectively, assuming a conser-
vative design approach using eight blocking wells.
-------
-18-
The Responsiveness Summary to the public comment is attached to this
Narrative Summary.
Consistency with Other Environmental Laws
All three proposed alternatives are consistent with other Federal and State
environmental laws. The Wisconsin State Implementation Plan (SIP) esta-
bilishes air emission limits for the release of VOCs into the ambient air.
The Wisconsin Administrative Codes NR 147.02 regulates the limit for dis-
charges of contaminated water into the Chippewa River. The WDNR and U.S.
EPA evaluated Alternatives 1, 2, and 3 in terms of potential compliance
with these regulations.
Alternatives 1 and 2 would result in the discharge of contaminated ground-
water into the Chippewa River. The estimated discharges would be approxi-
mately 10 mgd for Alternative 1 and approximately 4.25 mgd for Alternative 2.
The WDNR did a preliminary assessment to evaluate the contaminated ground-
water discharges in light of U.S. EPA 1980 water quality criteria for
protection of aquatic life. The impact of the discharge was compared with
acute and chronic toxicity levels where specific limits were available.
Preliminary findings showed the maxinum contaminant concentrations in the
discharges estimated in Alternatives 1 and 2 to be significantly below any
of the defined criteria, prior to dilution by the river flow. In light of
the findings of this initial assessment, WDNR concluded that treatment of
the contaminated groundwater prior to discharge would not be necessary. If
Alternatives 1 or ~ were selected, WDNR would investigate the discharge
question in detail 'and establish a not to exceed discharge limit. A permit
would be required for either Alterr.ative 1 or 2 under Wisconsin Regulation
NR 147.02, as both alternatives would result in a discharge to a state
waterway.
Alternatives 2 and 3 would result in the release of air emissions from the
air strippers. The FFS evaluates estimates of potential air emissions from
Alternatives 2 and 3. The estimated emissions were developed on both an
averaye case and worst case basis.
The average case basis assumes that the air stripping system will experience
raw water influent flows wtth contaminant concentrations to be equal to the
second highest concentrations reported in test wells or production wells in
the well field for each compound, except l,l,l-trichloroethane. For this
compound. the two outstanding values (188 and 155 ug/1) were assumed to be
atypical, and the next highest value (50 ug/1) was chosen. Under this
scenario, it can be anticipated that Alternative 2 would result in 5.34 lbs/
day of air emissions and Alternative 3 would result in 13.09 lbs/day of air
emissions. Although average future contaminant concentrations and air emis-
sions cannot be predicted to a high degree of certainty, it appears reason-
able to assume. that the average case estimations are conservative.
The average case air emission estimates are considered conservative because
second highest and third highest groundwater 'contaminant concentrations
were assumed to be the influent water quality to the proposed air strippers.
These concentrations of contaminants were assuMed to have spread uniformly
through the entire north well field. Contamination is currently observed
above trace levels at fewer than half (four out of nine) of the production
-------
-19-
wells in the north well field. Therefore. current average groundwater con-
taminant concentrations are substantially below those used to estimate
average case air emissions.
The worst case estimates assume that the air stripping system will experience
raw water influent flows with contaminant concentrations equal to design
concentrations (i.e., 1.25 times the maximum reported concentration for each
compound ever detected in production or test wells in the well field). Under
this scenario it can be anticipated that Alternative 2 would result in lfi.05
lbs/day of air emissions and Alternative 3 would result in 39.40 lbs/day of
ai remiss ions.
In order to provide compliance with applicable air pollution regu1ations,
it can be anticipated that some type of air emission control system would
be required for both Alternatives 2 and 3 under the worst case scenario.
The Wisconsin SIP Regulation NR 154.13(11)(1)(4) requires that source VOC
emissions cannot exceed 15 lbs/day. Both Alternatives 2 and 3 can be
expected to exceed the 15 lbs/day limit in this worst case scenario. In
Alternative 2, the total influent organic load (lbs/day) to the stripping
tower would have to increase approximately thi~teen-fold above the current
conditions before air emissions control would be required. In Alternativp. 3,
the total influent organic load (lbs/day) to the stripping tower would have
to increase approximately nine-fold above current conditions before air
emissions control would be required. U.S. EPA does not currently possess
any data to support either a thirteen-fold increase or nine-fold increase
in conta~inant concentrations. Such an increase would represent a ~ajor
departure from the;increase in contamination seen at this site over the
last four years. In the event that such a dramatic increase did occur,
air emission control systems would Most probably be required. This would
result in increased costs for either Alternative 2 or 3. Both air strip-
ping systeMs could be readily retrofitted with air emission control systeMs
to ensure compliance with the Wisconsin SIP.
Although under a worst case scenario it appears that an air emission control
systeM would be required in Alternatives 2 and 3; under a reasonably conser-
vative scenario of average conditions, air emission controls would not be
required by either Alternatives 2 or 3.
. I
Public Health Risk Assessment Due to Air Stripper
U.S. EPA Air Management Division performed a health risk assessment to
evaluate the health risks which could arise from the emission of the con-
taminants as air pollutants if the air stripping technology is implemented
as outlined in Alternative 3. The health risk assessment was conducted for
both scenarios for predicted air emissions as described above in Consistency
with Other Environmental Laws section assuming: 1) influent water flows
with contaminant concentrations equal to design concentrations and 2) ,
influent flows with contaminant concentrations to be equal to the second
highest reported concentrations, except for 1,1,I-trichloroethane in which
third highest reported concentration was used. The memorandum summarizing
the results and conclusions of this risk assessment is attached.
The results of the air risk assessnent indicate that the public health risk
due to the air emissions froM an air stripper as proposed in Alternative 3
is of little significance considering the average and worst case air emission
estimates discussed above in "Consistency with Other EnvironlTM!ntal Laws" at
-_....~--:--~.:"""'~.-.
-------
-20-
page 17. Based on the results of the air risk assessment. it can be conclude~
that a carbon adsorption treatment system for the air emissions would not
be necessary to further minimize health risks.
Recommended Alternative
-4---------------
The National Oil and Hazardous Substances Contingency Plan (NCP) [40 CFR
Part 300.68(j)] states that the appropriate extent of remedy shall be
determined by the lead agency's selection of the remedial measure which the
agency determines is cost-effective (i.e.. the lowest cost alternative that
1s technologically feasible and rel iab1e and which effectively mitigates
and minimizes damage to and provides adequate protection of pub1i~ health.
welfare. or the environment). Based on the evaluation of cost and effective-
ness of each proposed alternative. the comnents received from the public
and the WDNR. and State and Federal environmental requirements. Alternative
3 has been determined to be the cost-effective alternative.
The recommended alternative is considered an initial remedial measure (IRM)
as defined in section 300.68(e)(I) of the NCP. An IRM is appropriate
because there is contamination of drinking water at the tap. The objective
of the action is to provide those consumers currently dependent on the Eau
Claire city water with safe. potable drinking water until the final remedial
measure(s) may be implemented. The RIfFS currently underway will exaMine
appropriate final response action(s). . .
The recommended alternative provides for packed tower aeration treatment
for 14 Mgd of contaMinated groundwater. This treatment systeM would be
sized to allow for the possibility of contamination of the entire north
well field. Presently four of the nine wells in the north well field are
significantly contaMinated. Although the origin and migration paths of
the VOC contamination are currently undefined. the Migration will possibly
move in a north and west direction thus presenting potential for further
contamination of the remaining north well field.
The aeration treatment system would be designed to treat water with influent
volatile organic concentrations of 1.25 times the maximum reported concen-
tration in any production well or test well found in the north well field.
The aeration treatment systeM would be designed to achieve 99.6% removal of
the critical contaminant 1.1-dich10roethene. This removal efficiency would
provide finished water at less than a cu~ulative 1 xlO-6 excess lifetime
cancer risk.
The capital cost of this alternative is estimated to be $1.420.000. The
operation and Maintenance costs are estimated to be SIQ5.000 per year for
electric power and operating labor. The five-year present worth value for
the recomMended alternative is $2.160.000.
It is recomnended that EPA fund 90 percent of the O&M costs for a period not
to exceed one year after cOMpletion of construction. Based on an agreement
with the State of Wisconsin. the City of Eau Claire will provide the 10%
O&M match for the first year and then assume all O&M for the life of the
project.
.. "~.~'"--"'~!~:f..
. "" ~'"
-------
-21-
Recommended Alter~ativ~~}t Relates to Final Remedy
As discussed above, the National Contingency Plan states that an IRM can
and should begin if such measure is determined "to be feasible and necessary
to limit exposure or threat of exposure to a significant health or environ-
ment hazard, and if such measures are cost-effective. 40 CFR 300.68(e)(1).
Currently, the Eau Claire Well Field supplies drinking water to over 57,500
residents. The residents are potentially exposed to a variety of VOCs
contained in the groundwater system. These compounds (see discussion at
page 4, above) are suspected carcinogens.
The two ways to approach a final remedy at this site are minimization and
mitigation of the groundwater contamination and use of an alternative water
supply. Although the final remedy for this site has not been determined,
it appears likely that some type of response to minimize and mitigate the
current groundwater contamination will be the final remedy. It is not
likely t~at the final remedy will be use of an alternative water supply.
It is likely that the air stripping treatment system will be incorporated
into a final remedy selected, as part of minimization and mitigation of the
groundwater contamination. depending on results of the ongoing RIfFS.
There are two categories of technologies to address minimization and
mitigation of groundwater contamination: treatment and source control.
It is likely that the final remedy will be either a treatment type remedy
or a source control/treatment type remedy. The air stripping system could
be used in either Qne of these situations.
.
First, the Agency may utilize the air stripper in a treatment type final
remedy to address contamination. In that case, the contamination may
be extensive and dilute in the aquifer. such that source control is not a
viable alternative. In that case, the only way to minimize and mitigate
the groundwater contamination would be through utilization of the air stripping
system, which would treat or clean up the groundwater. This would possibly
be in conjunction with another treatment type technology.
Second, the Agency may utilize the air stripper as part of a source control/
treatment type remedy at the site. In that case, the air stripper would be
utilized to treat or clean/up already contaminated groundwater. The clean
up effort would be in conjunction with a source control remedy implemented
upstream of the groundwater contamination in the Eau Claire Well Field.
Final remedies at the Eau Claire site which do not include minimizing and
mitigating the groundwater contamination are very unlikely. The Eau Claire
well field is ideally located in that, without the VOC contamination, the
quantity and quality of water is good. There is no isolated uncontaminated
aquifer in the immediate vicinity that could provide the necessary quantity
and quality of water. Similarly, alternative water supplies (i.e., non-
groundwater supplies) such as connection with another municipal systen and
surface water sources have been determined as not feasible for an IRM ann
will likely be determined as not feasible for a final remedy. There is no
system with adequate capacity to make that option technically feasible. The
average daily demand for water from the well field for the past three years has
not exceeded 9.4 mgd (maximum demand, 19.8 mgd). Therefore. the final re~edy
will likely include minimizing and mitigating the groundwater contamination.
not use of an alternative water supply.
-------
-22-
Although the air stripping system may not eliminate the contamination of
the well field aquifer, this IRM will minimize the threat posed by the
contamination until such time as a final remedy is selected by U.S. EPA.
As the RI/FS is currently underway, the extent of groundwater contamination
is now being evaluated. Until the evaluation is completed, it is not
technically feasible to develop a cost-effective, long tenm remedy for the
site.
Threfore, the IRM will effectively meet two Agency goals. "The IRM air
stripping syste~ achieves the primary goal of limiting exposure to a signi-
ficant health threat by providing safe potable drinking water to those
citizens currently dependent on the municipal well field. In addition, the
air stripping treatment system works towards the likely final remedy of
minimizing and mitigating groundwater contamination in the well field by
providing treatment for 14 mgd of contaminated groundwater.
State Agreements
Section 104(c)(3) of CERCLA sets forth the State financial responsibilities
in remedial actions provided under CERCLA. The State financial responsi-
bilities in the proposed remedial action would include payment or assurance
of payment of 10 percent of the costs of remedial action, and assurance of
all future maintenance costs of the remedial action.
Although the City of Eau Claire owns and operates the well field, the Agency
does not currently possess any information to support a finding that the
City of Eau Claire pwned the well field at the time of any disposal of
hazardous substanc~s. In fact, due to the nature of the contamination
i.e., groundwater contamination, U.S. EPA does not currently possess any
information to support a finding that any hazardous substances were disposed
of on the well field. It is possible that the source of contamination lies
beyond the property boundary of the well field. Therefore, this site is
currently subject to the 10% match to Federal Superfund monies spent at
this site.
The State of Wisconsin Secretary of WDNR has sent the Region V Regional
Administrator a letter acknowledging the State financial obligations in
this remedial action. The State has received a commitment from the City
of Eau Claire to assume all operation and maintenance (0 & M) costs of
the IRM.
The 0 & H costs will be covered under a cooperative agreement between the
State and U.S. EPA at the completion of construction of the IRM.
Schedule
The REM II contractor CH2M Hill will manage the design of the IRM. The"
U.S. Army Corps of Engineers will procure the construction contractor and
oversee construction activities. The schedule for design and construction
activities is as follows:
lAG with Omaha district USACOE
05/09/85
06/07/85
Approval Remedial Action
(Sign ROD)
_..,~..-.__.~.~~'~
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-23-
Hill Submits draft Design Work Plan
06/07/85
Advance Notice to Prospective Bidders
in Commerce Business Daily
Hill completes Design
07/29/85
07/31/85
Design reviewed by U.S. EPA, State,
& COE
Advertise for Competitive Bids
Open Bids
08/12185
08/21/85
Contract Award
09/10/85
10/01/85
Notice to Proceed
10/31/85
Estimated Construction Period
22-26 weeks
Future Actions
An RI/FS for the final remedy will be fully underway this summer. The
objectives of the RI/FS are to determine the extent of contamination at the
site, to determine the hazard potential of the site, and to evaluate poten-
tially feasible remedial actions. The feasibility study will recommend the
most cost-effectiv~ remedial action(s) for the site.
.I
..._.-~~-~
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"".HUlln
UOUID
.
ACTIVI MOOUCTION WILLI
@
C-~ MUNICI'AL WELL FIELD
.
o
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JDaO
ICALiIN Pin
. .
FIGURE I
VICINITV MAP
EAU CLAIRE MUNICI'AL WI.... 'IILD
...---~~;~~
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~
J
-... -- -
- .
:..~ -
...".. Da'vi
x
x
~
x
x
...... O_...~
-
P'''''''U''Sf
I
LICIIND
X' WlU.SAM'LES
., WILL SAM'LES WITH CONTAMINANTS AT LEVeLl
a"UTIA THAN 1 X 1~ CANC!" "ISIC LEVEL.
@
0 '000
I
2000.'
ICALiIN PlIT
FIGURE ..
CONTAMINAT~D WELL
DISTRIBUTION
I!AU CLAIRE MUNICI'AL WELL 'IELD
!" ~~.
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COMMUNITY RELATIONS RESPONSIVENESS SUMMARY
EAU CLAIRE MUNICIPAL WELL FIELD
EAU CL~IRE, WISCONSIN
The United States Environmental Protection Agency
(U.S. EPA) has conducteQ a Focused Feasibility Study (FFS) to
evaluate Initial Remedial Measures (IRM) at the Eau Claire
Municipal Well Field, Eau Claire, Wisconsin (EC Well Field).
The FFS was completed on April 11, 1985, under the authority of
the Comprehensive Environmental Response, Compensation, and
Liability Act (CERCLA), 42 U.S.C. 9601 et seq., and in accordance
with the ~ational Contingency Plan (NCP), 40 C.F.R. Part 300.
The U.S. EPA recommended that a packed tower air stripping
treatment system was the appropriate I~~1 for the F.C Well Field.
~1e public:comment period to revie~ tne recommended
alternative as well as the FFS opened on April 15, 1985.
The
U.S. EPA did not receive a request for a Formal public hearing.
Upon consultation wit~ the state and local officials, it was
determined that a press conference would be appropriate and a
conference was held on April 18, 1985 in the Eau Claire City
I
Rall. The results of the FFS were presented to the press.
Finally, a public informational meeting was held on the evening
of April 18, 1985.
The purpose of tnis meeting was to present
the results of the FFS to interested members of the public and
answer any questions.
Although locally publicized,this meeting
was attended by a few State and Local officials, the press, and
one area industry representative.
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I .
SITE BACKGROUND
The EC Well Field, a 500 acre site, is located in north-
west Eau Claire County, Wisconsin at the confluence of the
Eau Claire River and the Chippewa River.
At pres~nt, this City
The EC Well Field
Water System is supplied by groundwater.
supplies drinking water to approximately 57,500 residents and
to numerous commercial and industrial establishments in the
City of Eau Claire and the Town of Washington.
The City-owned
water system includes 14 active wells, a water treatment
facility, and 3 ground level storage reservoirs.
In March of 1981, as a part of the U.S. EPA's Groundwater
supply survey, the Wisconsin Department of Natural Resources
(WDNR) tested the Eau Claire municipal water supply for volatile
I
organic compounds (VOC).
Four organic compounds were identified
in the municipal water supply:
l,l-dichloroethene, l,l-dichlor-
ethane, 1, 1, l-trichloroethane, and trichloroethene.
Additional
testing continued through 1983 and samples from all but one
well reported VOC concentrations at low or trace levels.
By
the Spring of 1983, WDNR had nominated the EC Well Field as a
I
potential Superfund site.
Furt~er testing uncovered the follow-
ing organic compounds in th.:! EC Well Field or nearby residential
wells: tetrachloroethene, 1,2-dichloroethene, and 1,2-dichloro-
ethane.
On September 11, 1984, the EC Well Field was included
on the U.S. EPA Superfund National Priorities List.
Contaminated wells at the EC Well Field appear to be con-
fined to 2 areas.
Municipal wells 11, 15, 16 and 17 in the
. ,--~",.,~,,,,:oo-:-:.,-,-:.,,:,,,,:,.:.
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northern part of the well field and 2 private wells nearby show
the highest levels of contamination.
II.
U.S. EPA REMEDIAL RESPONSE ACTIVITIES
The U.S. EPA began a remedial investigation pursuant to
CERCL~ and the NCP in January, 1985.
~1e purpose of the
investigation is to determine the nature and extent of'contami-
nation of the EC Well Field.
Field work for this investigation
should be underway in the Summer of 1985.
Due to the fact
that over 57,500 residents are currently receiving water from
the EC Well Field, U.S. EPA has determined that an initial
remedial action to minimize the threat posed by the contamina-
tion of the drinking water is appropriate.
A Focused Feasibility
Study to addres~ the concern regarding drinking water was
completed on April 11, 1985.
III.
STATUTORY AUTHORITY
Section 104 of CERCLA by delegated authority, enables
U.S. EP~ to act, consistent with the ~CP, to remove or arrange
for removal of, and prpvide remedial action relating to a
hazardous substance, pollutant, or contaminant at any time, or
take any other response measure consistent with the NCP which
is deemed necessary to protect the public health, welfare, or
environment.
42 U.S.C. ~9604.
Consistent with Section 105 of
CERCLA, the NCP establishes the methods and criteria for effect-
uating a response measure that protects the public health,
welfare, or environment in a cost-effective manner.
. .,...~..~."'..,~~~.?~.w
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42 U.S.C. ~9605.
subpart F of the NCP, 40 C.F.R. Parts 300.61
through 300.71, set forth the criteria for hazardous substance
response.
Remedial actions are specifically addressed in 40
C.F.R. Part 300.68.
IV.
SUMMARY OF ALTERNATIVE CHOSEN BY THE U.S. EPA
AS THE APPROPRIATE INITIAL REMEDIAL MEASURE
AT THE £AU CLAIRE MUNICIPAL WELL FIELD
The U.S. EPA has determined that the Alternative 3 as
identified in the FFS is the appropriate IRM for the EC Well
Field.
This alternative will provide treatment for the
contaminated groundwater supplied by the north E~ Well Field.
The selected alternative involves providing air stripping
facilities to remove organic compounds from the contaminated
flow from the n~th well field.
Since blocking wells are not
part of this alternative, the plume of contamination may migrate,
thus contaminating the remaining north well field.
The remedy
is therefore being sized to strip sufficient water to meet
water system requirements when coupled with the remaining
uncontaminated wells. The treated water would be discharged
I
into the municipal water treatment plant and distribution
system.
No discharge of contaminated water to the river would
be necessary.
The currently estimated capital cost of this IRM is
$1,230,000.
The operation and maintenance of this remedy is
expected to cast approximataly $195,000 per year.
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~
v.
COMMENTS
During the public comment period 4 written comments were
received by U.S. EPA.
The public comment period closed on
May 6, 1985.
Two additional comments were received by U.S. EPA
after the close of the comment perion.
Due to the limited
number of comments U.S. EPA is responding to each of them.
COMMENT:
The City of Eau Claire commented that it agreed with the
U.S. EPA's recommendation to use the packed tower air stripping
treatment system.
RESPONSE:
The U.S. EPA acknowledges the support of the City of
I
!
Eau Claire.
COMMENT:
One commentator asked if the Superfund could be used to
drill new city wells in an area of uncontaminated groundwater
and thereby deliver safe potable water to the citizens currently
I
dependent upon the Eau Claire Well Field.
RESPONSE:
Yes, the u.S. EPA can theoretically use Superfund monies
to drill new city wells.
The feasibility of drilling new city wells in areas of
uncontaminated groundwater was evaluated in the FFS, however,
this alternative is not feasible in the case of the EC Well
. .-..-'. . ..'" ., ~
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Field.
There is only one aquifer in the vicinity of the city
well field.
The possibility of drilling wells into an isolated,
uncontaminated aquifer does not exist.
The possibility of
drilling new city production wells in an uncontaminated region
of the existing aquifer was examined in detail as part of
Alternative One in Chapter 6 --- Detailed Alternative Analysis~
This alternative was, however, determined less feasible than
the recommended packed tower air stripping treatment system.
COMMENT:
One commentator asked if Superfund monies could be used as
seed money for a water distilling plan if the plan was limited
to drinking and cooking purposes.
I
I
RESPONSE:
It appears unlikely that a water distilling plan could be
funded by Superfund monies.
The NCP states that initial remedial
measures using Superfund monies can and should beqin if such
measures are determined to be feasible and necessary to limit
exposure or threat of .xposure to a significant health threat
or environmental hazard, and such measures are cost effective.
40 C.F.R. Part 300.68(e)(I).
The health threat at the Eau
Claire Municipal Well Field is drinking water contaminated at
the tap with volatile organic compounds.
Although a water
distilling plan, properly implemented, would remedy the health
threat at Eau Claire, the costs of implementing such a plan
\
would be so high that it would not be cost effective.
Other
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- 7 -
reliable technologies exist for dealing with the drinking water
contamination problem at Eau Claire which are not as expensive
as a water distilling plan.
COMMENT:
One commentator asked '-''hat technologies can be implemented
under the Superfund program.
RESPONSE:
Any technology can be implemented as an IRM as long as it
meets the qualifications as outlined in the NCP. 40 C.F.~.
300.68(e)(l).
An IRM alternative must be:
1) feasible,
2) necessary to limit exposure to a significant health threat
or environmental hazard, and 3) cost effective.
I
!
COMMENT:
The State commented that 2 private residential wells in
the immediate vicinity of the EC Well Field are contaminated
at levels greater than the contamination of the EC Well Field
water.
The State also indicated that no provisi~ns have been
I
identified in the FFS to address this problem.
RESPONSE:
The U.S. EPA is aware of the contamination of the D. and
J. ~illman private residential wells located at 715 E. Riverview
and 3714 Airport Road.
~e U.S. EPA has modified the current
plan regarding the IR~ to include an investigation of alternatives
to remediate this contamination.
-. "~ ,.. .... ':- ''': "".', .-.
'. ....:'
. . . .
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COMMENT:
The last comment involves private residential wells.
The
State commented that other private residential wells in the
immediate vicinity of the EC Well Field may also 'be contaminated
and aSKS the U.S. EPA to address this issue.
RESPONSE:
Currently, U.S. EPA does not possess any data that indicates
contamination of private residential well at concentrations
that pose a risK sufficient to justify an IRM (with the exception
of the qillman wells, discussed in the prior comment).
The
U.S. EPA recognizes, however, that other private wells in the
im~ediate vicinity of the EC Well Field may currently be conta-
minated or will be further contaminateo in the future.
.'
This
potential risK is one of the reasons U.S. EPA is proceeding
with a Remedial Investigation/Feasibility Study (RI/FS) at the
EC Well Field site.
The purpose of an RI/FS is to define the
nature and extent of contamination at the EC Well Field and
the surrounding vicinity.
It is anticipated that the data
generated by the RI/F~will identify any contamination in
private residential wells in the immediate vicinity of the
EC Well Field.
If the data indicates that the levels of
contamination exceed appropriate levels, the Agency will respond
to the situation at that time.
Should the situation warrant an
immediate response prior to the implementation of a final remedy
at the entire ~C Well Field site, that action will be taKen.
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