United States
Environmental Protection
Agency
Off)oa of
Emergency and
Remedial Retporae
EPA/ROD'R05-85.017
August 1985
Superfund
Record of Decision;
Main Street, IN
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TECHNICAL REPORT DATA
(Pita, ft,d IttltfUctiottl Off th, ftvm, ""on com"t"itt,)
1. ...'O..T NO. 12. 3. RECIPIENT'S ACCESSIOIIIIIIO.
EPA/ROD/R05-85/0l7
.. TITLE AND SU8TITLE II. REPORT DATE
August 2, 1985
SUPERFUND RECORD OF DECISION 8. PERFORMING ORGANIZATION CODE
-
Main Street, IN - - .
7. AUTHOR.SI .. PERFORMING ORGANIZATION REPORT "'0
I. P.R'O..MING ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT NO.
".-CON~~T/GJfANT NO.
12. IIPONSO"ING AOENCY NAME AND ADDRESS 13. TYPE OF REPORT AND PER'OO COVEREO
Final ROD Report
U.S. Environmental Protection Agency 1.. SPONSORING AGENCY CODE
401 M Street, s.w. 800/00
Washington, D.C. 20460
18. SUPPLEMENTARY NOTES
:'8. ABSTRACT
The city of Elkhart is located in north central Indiana in Elkhart County.
Three well fields. supply drinking water to approximately 37,000 of the city's
residents. Main Street Well Field is the largest of the three well fields consist-
ing of 15 wells on 10 acres, and supplies 70-80 percent of the city's water needs.
In April 1981 during an u.s. EPA Groundwater Supply Survey, volatile organic compounds
were detected in water furnished from Main Street Well Field. The compounds detected
included trichlorethylene (TeE), 1,2-dichlorethylene, l,l,l-trichlorethane and
l,l-dichlorethane. Concentrations of contaminants ranged from 2.0 parts per billion
(ppb) of l,l-dichlorethane to 94 ppb of TCE.
The selected remedial action includes construction of air stripping facilities
to remove volatile organic compounds from the contaminated flow from the Main
Street Well Field. The treated water will be discharged to the existing water
treatment plan and distribution system. Total capital cost of the selected remedial I
alternative is estimated to be $1,106,000 with O&M costs estimated to be an I
additional $158,000 per year.
!
.
7. KEY WO"DS AND DOCUMENT ANALYSIS I
DESCRIPTORS b.IDENTIFIERS/OPEN ENDED TERMS C. COSATI Field.t,;r, '.:' I
Record of Decision I
Main Street, IN
Contaminated Media: gw, soil 1
Key contaminants: VOCs, trichlorethylene !
(TCE), 1,2-aichlorethylene (1,2-DCE), i
.1, 1, 1-tri chlorethane, l,l-dichlorethane,
and tetrachlorethylene (PCE) I
~.. DISTRIBUTION STATEMENT 19. SECURI T Y CLASS, TIlls Report, 21. NO. OF PAGES !
None 28 i
20 SECURITY CL~SS ITilisp".~,.: 22. PRICE !
None I
:
I'. ,- 2220-1 (I...4-n)
....IIYIOIJ5 IICIToON'1 0810L..IITE
. ...~_.. ....--....
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INSTRUCTIONS
,.
RE,<)RT NUMBER
Inserllhe EPA reporl number u itappnn on Ihe cover of Ihe publk:alion.
2.
I.
LEAVE BLANK
- -
4.
RICIPIENTS ACCESSION NUMBER
Rnerved for use by ea.:h report retipienl,
TlTLI AND SUBTITLE
Tille should indicalf .:IC:iIrly and briefly Ihe subj"'1 ':ovl:ra~'\: of Ih.: r~'porl. and b.: lIi'l'lay~'lIl'romin.:nlly, S~'I sllhtilk. il'II~"11. m -mah,'r
type or otlscrwi. subordinalf illo main lille, When a report i~ I'rl:pared in mort lhan Oft(' mluml:, rl:p'aillt.: I'rnnOiry Iilh:. 011111 VI":IIII':
numllfr and include sublille ror Ihe specific lille.
L
RI~T DATI
Each reporllllall carry a dale indiClIiniallca51 monlh and Yl:aI, Indkllll: Ih.: ha.., on ~.ltidl il '\;Is ",,'II:~'I~'II (,',Il" Jill" "' ;mcc'. Jtll., III
qproNI, .,, olprtptllfltion, tiC,),
"RPOIIMlNO DRGANIZATlDN CODE
Leave blank,
..
7.
AUTHDRIII
Give narnr(sl in .:»nvc:nliona' order (Joim R, /)0(0, J, Robt." Doc', ('Ie), Li~1 iIulhor'~ a1'liliOllloll if it Ji""~'r, hum 11t~. ,...rfurmilll! ",pni.
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..RFDRMING ORGANIZATIOI\j ,
'uert if pcrrormlftl orpnization WISt.
lRT NUMBER
) a5sign Ihis number,
t.
"RPORMING ORGANIZATION NAME ANO ADDRESS
Give name,ltreel, city. sllle, and ZIP cod~, LISI no more Ihan Iwo I~veb of an orltani/aliollalltirl:llrdlY,
1~ PROGRAMELEMENTNUM8ER
U. tlsc propam elemenl number under which Ihe reporl was pr.:pared, Suborllmah: numbers nl;l)' I,... indllJ"11 III 1I;II\'nlll,'"",s,
11. CONTRACT/GRANT NUMBER
IDIert CODIrlCI or panl number under which reporl W;U preparc:d,
,2. SPONSORING AGENCY NAME AND ADDRESS
Include ZIP c:ocIe,
,I. TVPI OF RE,<)RT AND PERIOD COVERED
IndiClle inlerun fmal. elr., and ir arpltcable. dales covered.
'4. 8'ONS0RING AGkNCY CODE
Insert appropriate code.
,.. SUPPLEMENTARY NOTES
Enlfr informalion not included ebewhere bUI useful. such as:
To be published in, Supersedes. Supplements. ~IC.
tI, A8STRACT
Include a brier (200 words 01' less) faclualsummary of Ihe mosl si~nili.:ant ,nformalinn .0nla,",',1 "' 110,' "'1'1111. II lit,. "'1'"'' ,,,"I,,"'s a
sipificanl bibliography or lileralure survey, men lion il her.:,
Prepared in o.:oop.:ralion wllh, I r."'sla 11"" "I, 1"':"'111,'" al ''""'','''"''' ..I,
17. KEY WORDS AND DOCUMENT ANAL VSIS
(a) DESCRIPTORS. SeIC':1 from Ihe Th':\OIuru\ of tn8In.:c:rir.~ .lIId So.:II'IIIII'. /~lIlIs Ih.: prop.:r aulh",,,.'J 1,'lIlIs Ihallu~IIIII~' Ih,' "'''1'''
concepl of Ihe research and are sufficienlly >pC:I:llic IInli pr~o.:is.: 10 bc u""J a, onu\'\ ,ntrles IUI .atah.~'n~,
(b) IDENTII'IERS A:'>ID opr~.I:~DED TERMS .l:~ Idenlifiers ror PIOIC..:! nam", .011.: lIam~s, "
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Record of Decision
ReMedial Alternative Selection
Operable Unit for Provision of
Alternate water Supply
Site
Main Street Well Field
Elkhart. I~diana
~ocuments Reviewed
This decision is based on t~e fol1owinQ docu~ents describing the analysis
of cost-effectiveness Of interim re~edial alternatives for the ~ain Street
Well Field site: .
- Phased Feasibility Study for ~ain Street \~e11 Field. r.1khart. Indiana.
Camp 'resser & McKee. P1ay 2q. 1~8~. and ADDEN~a~
- Su~ary of Re~edial Alternative Selection
- ~esponsiveness Summary
- Me~orandu~ from Steve ~othblatt. r.~ief. Air and Radiation ~ranch to
qichard Bartelt. Chief. Emergency and Remedial ~esponse qranc~
- ~emorandu~ fro~ Josep~ Harrison. Chief. Safe ~rinki~q Water ~ranch to
Richard Bartelt. Chief. Emergency and ReMedial Response ~ranch
- MemoranduM from Rohert A. Schaefer. Regional Counsel and Basil G.
Constantelos. Director. Waste Management Division to Valdas v.
Ada~kus. Regional Ad~inistrator
- Letters from Woodrow A. ~yers. Jr.. ~.n.. State Healt~ ~o~isio~er.
Indiana State ~oard of Health to Valdas V. Adamkus. Regional
AdMinistrator
Description of Selected Remedy
Construct air striDping facilities to remove volatile organic compounds
fr~ the contaminated flow from the ~ain Street Well Field. The
treated water will be discharged to the existinq water treatment
nlant an~ distribution system. The operable unit serves a dual
purpose. provision of a~ alternate water sunD1y and Manage~ent ~f
groundwater migrati~n.
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Dee larat ions
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 l!1unicipal water system
treatl!1ent and distribution is a cost-effective interim remedial
action (operable unit) and provides adequate protection of pUblic
health, welfare, and the envirJnment. The State of Indiana has been
consulted and agrees with the ap~roved re~edy. In addition, the action
will require future operation and ~aintenance activities to assure the
continued effectiveness of the re~edy. These activities will be
considered part of the approved action and eligible for Trust Fund
monies for a period not to exceed one year.
It has also been determined that the action being undertaken is con-
sistent with permanent remedy at the site, and is appro~riate when
balanced against the availability of Trust Fund mo~ies for use at
other sites.
The U.S. Environmental Protection Agency is continuing its remedial
investigation/ feasibility study (RI/FS) of the Main Street Well
Field site to define extent of contamination, evaluate potential
sources of contamination and the hydraulic characteristics of the
aquifer in order to evaluate potential final remedial actions. If
additional remedial actions are determined to be necessary, a Record
of Decision will be prepared for approval of the future remedial
actions.
Mi'
~~~,>f".z.; IriS
Dat
1 '. ,~
Valdas V. A amkus .
Regional Ad~inistrator
U.S. EPA, Region V
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NARRATIVE SUMMARY
Main Street Well Field
Elkhart, Indiana
1. Site Location and Description
The City of Elkhart is located in north central Indiana in Elkhart County.
Three well fields supply drinking water to approximately 37,000' of the City's
residents. Main Street Well Field is the largest of the three well fields
consisting of 15 wells on 10 acres, and supplies 70-80% of the city water
needs. It is centrally located in the City of Elkhart, with residential and
industrial areas on its border to the south and east respectively.
The Main Street Well Field is part of the St. Joseph River Basin area.
Christiana Creek, a tributary to the St. Joseph River, enters the well field
at the northwest corner and flows across the site in two major channels before
exiting at the southeast corner. The Main Street Well Field was designed to
utilize a man-made recharge pond system. Flow is diverted from Christiana
Creek to numerous ponds that recharge the shallow water table aquifer. All
15 of the wells in the field punp to two storage tanks before chlorination and
pumpage to distribution.
Tne a4uifer system in northwest Elkhart County consists of coarse sand and
gravel deposits averaging 175 feet in thickness. In the Main Street Well
Field area, sand and gravel (glacial outwash) occurs to depths rangin~
from 42 to 58 feet. Below this is a silt and clay layer, which is believed'
to slope to the west. The soil at the site is Oshtemo loa~y sand to .
depths of about 14 inches. This soil is described as a deep, well-drained
soil on glacial outwash with an estimated permeability of .04 cm/sec.
Tne underlying deposits consist of generall} fine to mediuM sand and
gravel, with coarse sand and gravel content increasing to the east of the
site. The permeability of the aquifer is in the range of .18 to .08 em/sec.
The underlying clay and silt layer has an estimated permeability of 1.6 x
10-7 em/sec.
The direction of regional groundwater flow is generally south, towards the
St. Joseph River and its tributary, Christiana Creek. In the well field area
there is a westerly component to the flow, particularly toward the eastern
border of the well field. The groundwater flow in this area is subject
to influence by natural factors, such as Christiana Creek and by groundwater
pumpage and recharge. The effect of the Main Street Well Field on groundwater
flow patterns is dependent upon groundwater levels; the number, location and
rate of pumping of the supply wells; and recharge from Christiana Creek.
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2.
Site History
In April of 1981 during an U.S. EPA Ground Water Supply Survey, volatile
organic compounds (VOC's) were detected in finished water from the Main
Street Well Field. The compounds detected included trichlorethylene
(TCE), l,2-dich10rethylene (l,2-DCE), 1,1,1-trich10rethaoe, and
1,1-dichlorethane. Coocentrations of contaminants ranged from 2.0
~arts per billion (ppb) of l,l-dichlorethane to 94 ppb of TCE.
A combined effort by the U.S. EPA, the Indiana State Board of Healt~
(ISBH) and the City of Elkhart was then undertaken to determine. the
sources of contamination. All 15 production wells ~lus 5 observation
wells were sampled between July and October of 1981. Trichlorethylene
(TCE) was found in 13 of the 15 production wells at or above the
detection limit. The highest concentratioo of TCE in a production
well was 880 ppb, which represents a 2.1x 10-4 cancer risk level. The
highest concentration detected in the observation wells at the eastern end
of the well field was 3300 ppb of TCE, which represents an 1.2 x 10-3
cancer risk level. Other VOC's were also detected, but none as consistently
or at levels as high as TCE. These contaminants are believed to be
deyradation products of TCE. The most contaminated wells lie on the
eastern sections of the well field. Potential sources of contamination
were indicated northeast of the field.
In an effort to bring TCE concentrations in finished water down to acceptab'
levels, five production wells from the contaminated eastern area of the
field were removed from service. Additionally, two interceptor wells
were installed by the City in 1982 to prevent further introduction of
contaminants into the well field. A sa~pling schedule to monitor TCE
concentrations in finished water and in production and observation wells
was also established by the City. Pumping practices were altered so that less
contarninad wells were pumped more heavily. Pumpages from the City's other
two existing well fields were also increased to meet water supply demands.
Despite these strategies, a steady increase in TCE concentrations in finished
water has occurred since 1982. In late 1983, two wells from the previously
uncontaminated western area of the field began to show high TCE concentrations.
In 1984 the finished water from the Hain Street Well Field exceeded the
1 x 10-& cancer risk level at an 87 percent frequency; during ~ay through
August, the period of highest historic water demand in Elkhart, the
finished water exceeded the 1 x 10-6 cancer risk level at a 95 percent
fre~uency. The following table compares the values for 1982 through
1985.
~ ._-. ......-,. ---,..,.. .
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-3-
Main Street Well Field Finished Water
Frequenc~ of Exceeding TCE Concentration. ppb
Period 1 x 10- Cancer Risk Average High Low
Year Round
1982 15% 1.8 3.9 0.62
1983 3~ 2.4 4.09 0.90
1984 871. 4.4 9.36 1.08
1985 (Jan-June) 56\ 3.3 5.19 1.52
~ August 40% 2.6 3.9 1.29
982
1983 24% 2.55 4.09 1.04
1984 95% 4.1 7.93 1.08
1985 (May-June) 1001. 4.4 5.19 3.85
A survey conducted by the City of Elkhart identified two industries.
Durakool and Excel. as potential sources of contamination of the well
field. This was later confirmed by monitoring wells located between
production wells and these industrial sites.
In late 1982. the Durakool and Excel individually contracted with Clyde
E. Willians and Associates to prepare independent reports investigating
the extent of TCE contamindtion and recommended remedial alternatives. The
soil data available from the reports showed TCE concentrations on these
properties ranged from 60 ppb to 570.000 ppb. Subsurface soils showed
extensive TCE contanination to depths of 40 feet. Maximum concentrations
occurred at 12 to 16 feet (20.000 ppb) with concentrations to 4.000 ppb
at 37.5 to 40 feet on the Durakool property. and 4 to 8 feet (270.000 ppb)
with concentrations to 5.300 ppb at 37.5 to 40 feet on the Excel property.
The proximity of the two industrial sites to the wells indicates that
contamination percolating from these areas may be captured within the
drawdown cone of the production wells and ultimately appear in the
public water supply. Deep soil borings (up to 40 ft) suggest that TCE.
being denser than water. has vertitally leached and settled to the gray
clay silt layer. where it forms a zone of contaminated s011 in and above
the layer at each of the probable source sites.
3. Current Site Status
All 15 wells in the Main Street Well Field have shown measurable levels
of TCE. Ten of the 15 wells have shown levels of TCE greater than 2.3
ppb. the 1 x 10-6 cancer risk level (U.S. EPA Carcinogen Assessment Group).
As of March 1985 sampling by U.S. EPA. 7 of the 15 wells exceed the 1 x
10-6 cancer risk level for TCE. The level of TCE detected in finished
water from Hain Street ~ell Field thus far in 1985 ranges between 1.52 and
4.39 ppb. This does not fully reflect the May through August period of
historical heavy demand. during which time more of the contaminated wells
must be incrementally put into production. resulting in increased levels
of TCE and other vacs in the water provided to the public.
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Tetrachlorethylene (PCE), previously undetected at significant levels
in the well field, was recently detected in the westernmost wells at
a level of 9.0 ppb. This corresponds to a cancer risk level of 9 x 10-6
and suggests an additional western source of contamination may exist.
Trans-1,2-dichlorethylene (trans- 1,2-DCE), was also detected in half
of the wells sampled at levels ranging from 1.2 - 4.6 ppb. A
10-6 cancer risk level has not been established for this co~pound.
The contaminated soils identified through previous studies have not
yet been removed. The RIfFS planned to be~in in the fall of 1985
will address all necessary source control and soil removal issues.
Other U.S. EPA actions instigated in July 1985 under the removal progra~
are being conducted in Elkhart that relate to residents with contaminated
private wells (see Attachments 2 and 3). Concentrations of TCE and other
VOCs in ~rivate wells have ranged from 0.7 to 19,380 ppb of TCE. These
recent findings have led to either emergency hook-ups to city water for
some residents or dispensing bottled water to others. It is possible that
removal actions will replace the temporary provision of bottled water
to these affected residents with hook up to City water. Though these
incidents appear as yet unrelated to Main Street Well Field, they are
indicative of the vulnerability to contamination of ground water in
the Elkhart area. As more and ~ore contaminated areas in Elkhart are
identified (see Attachment 4), providing a safe drinking water source is
imperat i ve.
4. Enforcement
See Appendix.
5. Toxicity of Pollutants
Five of the identified compounds in the drinking water from Main Street
Well Field, trichlorethylene, tetrachlorethylene, 1,1,1-trichloroethane,
1,1-dichloroethylene, and 1,2-dichloroethane, are suspected human carcinogens
based on research done by various entities. These compounds are not yet.
regulated by the Safe Drinking Water Act, but are currently in the
regulatory promulgation process.
The U.S. EPA Cancer Assessment Group (CAG) has established cancer risk
levels for the susp~cted carcinogens found at Main Street Well Field.
The 1 x 10-6 cancer risk levels established by t~e CAG are listed
below:
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Contaminant
1 x 10-6 Excess
Li f et i me Risk
(Carcinogenicity)
~
Longer-Term
Health Advisory
(Toxicity)
(ppb)
Trichlorethylene (TCE) 2.8 75
Tetrachloroethylene (PCE) 1.0 ZO
1.1.1-trichlorethane 21.7 1070
l.l-dichlorethylene 0.23 70
1.2-dichlorethane 0.95 Not established
The 1 x 10-6 cancer risk level represents the estimated contaminant concen-
tration in drinking water which would result in an additional incident of
cancer per one million people. The cancer risk levels assume ingestion
of two liters of drinking water per day for 70 years by a 70 kilogram
adult. Drinking water is considered acceptable for consumption if it
does not exceed the 10-6 cancer risk level. longer term health advisories,
which address toxicity of the compounds, are based on ingestion of 1
liter per day of drinking water for up to 2 years by a 10 kilogram child.
It can be seen that the concentrations of trichloroethjlene and tetra-
chlorethylene have consistently exceeded the 10-6 cancer risk level.
In addition to these five suspected carcinogens, two other VOCs, trans-
1.2-dichloroethylene and 1,1-dichloroethane, have been detected at the well
field. A 10-6 cancer risk level has not been established for trans-l,2-
dichloroethyle~e; however, a 10-day health advisory of 270 ppb has been
established. No health risk numbers. either toxicity or carcinogenicity,
have yet been established for l,l-dichloroehtane.
6. Threat to Public Health
The contaminants present in the ground water at the Main Street Well
Field present a threat to the public health. Approximately 37,000 people
are potentially affected. The public is exposed to the contaminants from
the ground water after punpage and distribution through the City water
system to the tap. Three primary exposure routes exist: i~gestion of .
water, der~al absorption from bathing. and inhalation of vapors released
from the water durin~ bathing and other uses.
The contaminants present at Ma;n Street Well Field are chlorinated
compounds. Chlorinated compounds are irritants to the eyes and/or mucous
membranes. They are highly or moderately toxic via oral and/or inhalation
routes. Of the abov~ three ~rimary exposure routes due to contaminated
tap water, current knowledge and data limit a quantitdtive risk estirnation
. ~.~-_..,,_.... "--''''." .
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to a calculated cancer risk estimation due to ingestion only.
The Agency prepared a health effects evaluation in the Phased Feasibility
Study for the Main Street Well Field site (Chapter 4). The purpose of
the evaluation was to detenmine the potential public health risks associated
with continuing to use the contaminated ground water as a municipal water
supp ly.
Both present and potential health risk evaluations were performed, as
presented in the Addendum: Estimation of Risk to Public Health. The
present risk evaluation was performed utilizing current concentrations in
individual wells at Main Street Well Field, employing the same pumping
strategy as used by the City, which in essence is pumping from the least
contaminated wells preferentially, and incrementing with remaining least
contaminated wells to meet demand.
The potential health risk evaluation was also performed utilizing current
concentrations in individual wells, but employing an inverse pumping
strategy, pumping from the most contaminated wells preferentially, and
incrementing with remaining most contaminated wells to meet demand.
Several reasons for the need of this approach are presented below.
Because of past intrusion of contaminants, areas of the well field
undoubtedly contain contaminated soils as well as contaminated ground
water. As more wells are brought on-line to meet increasing demand, the
risk of tapping contaminated ground water increases even if new introdution
of contaminants into the well field is prevented. As pumpage increases,
groundwater flow patterns shift. As a result, the contaminant plume is
drawn to the area of highest pumpage.
Additi onally, westernmost well s not previously contami nated have recently
shown elevated contaminant levels. These wells show contamination not
only by trichloroethylene (TCE), but tetrach10rethylene (PCE) as well.
PCE has not been detected in the observation wells in the edstern end of
the well field toward the known potential responsible parties, and has
been previously undetected in any production wells in the Main Street.
Well Field. PCE is not thought to be a breakdown product of TCE. Hence,
an additional western source is suspected. Groundwater contamination by
vOts. detected in industrial process wells west of and in proximity to
Main Street Well Field, adds validity to these suspicions.
Table 1 summarizes the estimated public health risks associated with
continuing use of the contaminated ground water from Main Street Well
Field as a source of drinking water. It should be noted that t~e risk
estimates presented in Table 1 consider TCE and PCE only. Three.
other suspected human carcinogens have also been detected in the ground
wdter at Main Street Well Field. Two of these compounds, 1,1-dichloroeth/1~ne
and 1,2-dich10roethane with 1 x 10-6 cancer risk levels of 0.23 ppb and
0.95 ppb respectively. have cancer risk levels even lower than PCE (1.0 ppb)
and TCE (2.8 ppb). However, insufficient number of analyses exist for
these other VOCs to accurately use their ~resence in these risk evaluations.
As such, the estimates may understate the risk due to ingestion of drinking
water from Main Street Well Field.
-- ..,..._",... . .,.
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-7-
As presented below in Table I, the present health risk for drinking water
from Main Street Well Field consistently exceeds the 1 x 10-6 cancer risk
level. The 1 x 10-6 cancer risk level represents the estimated contaminant
concentration in drinking water which would result in an additional
incident of cancer per one million people. Furthermore, the potential
health risk evaluation indicates that the public health risk may approach
1 x 10-5.
Pursuant to developing Agency policy the 1 x 10-6 cancer risk level for
drinking water is the action level for providing an alternate water supply.
At this level of contamination, the threat to public health is sufficient
to warrant taking interim measures before final remedial measures are
implemented.
Table 1.
Summary of Estimated
Cancer Risk for Main
Street Well Field Wdter
Present Potential
Risk Risk
Average 1.R x 10-6 7.6 x 10-6
Daily
Demand
Da 11 y Dema nd 1.4 x 10-6 6.1 x 10-11
During f~aximum
f10nth
Maximum Daily 1.8 )( 10-6 4.3 x 10-6
Demand
Full Capacity 3.9 x 10-6 4.3 x 10-6
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-8-
7. Alternatives Evaluated
An operable unit is a discrete response measure that is consistent with a
permanent remedy, but is not the per~anent remedy in and of itself. This
is consistent with the practice of phasing remedial action at sites that
present complex cleanup problems.
The primary objective of the Main Streit Well Field operable unit is to
protect pUblic health by providing a reliable supply of safe, potable
water to those consumers currently dependent on the Main Street Well
Field. The long-term remedial measures will likely include minimiz1ng
and mitigating groundwater contamination affecting Main Street Well Field.
The selected remedy achieves the primary objective and works towards the
likely final remedial measure(s).
Numerous alternatives were identified and evaluated for ~otential as an
operable unit at Main Street Well Field in accordance with the NCP and
developmental EPA guidance for providing alternate drinking water supplies.
The alternatives were grouped into four general categories: 1) no action,
2) new water supply, 3) supplementary water supply, and 4) treatment.
The alternatives were evaluated in terms of their ability to protect
public health and their technical feasibility and implementability.
Time required to implement was considered a key criteria related to
ability to protect public health, in that higher summer water demands
necessitate pumping from wells with high contaminant levels, resulting in
elevated risk levels. Alternatives which could not meet these individual
criteria to at least a moderate de~ree were eliminated from furth~r
consideration. Table 2 presents the initial alternatives and summarizes
the results of initial screening.
The following treatment alternatives were advanced to further screening: air
stripping, granular activated carbon adsorption, and air stripping followed
by granular activated carbon adsorption. Table 4 outlines these alternatives
and the criteria upon which they were evaluated. In addition to ability to
protect public health and irnplementability, these alternatives were also
evaluated on co~plexity, reliability, environmental impact, community impact,
compatibility with final remedy, and relative cost.
All three alternatives presented below are designed to achieve the same
removal efficiencies. Required removal efficiencies are given in Table 3.
Design influent concentrations were based on a mass balance of the highest
concentrations of the various volatile organic contaminants found in each
well. These levels are generally one or two orders of magnitude greater than
the levels currently fo~nd in all 15 production wells. This conservative.
design approach was taken to ensure proper operating conditions and efficiencies
regardless of discontinuities in the data.
. .
~ : ... .
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Table 2. COMPARISON OF REHEDIAl ALTERNATIVES
Ab il ity Time Abil ity Result of
to Protect Required to Relative Environmenta1 COIIIIIunity to Meet Initia1
A 1 ternat he Public Health Implement Cost Complexity _.-!.mpac t - Impact Demand Screening
NO ACTION Poor Inmediate1y low low High High low Elimi nated;
unaccept-
ab1e for
long-term
consumption
ABANDON WELL FIELD
FOR NEW SUPPLY
Surface Water Supply
E1khart River Good 3-5 years High Moderate High Low low
J:limi nated ;
extended
St. Joseph River Good 3-5 years High Moderate Low Low High implemen-
tation time
New Well Fields
Ai rport Site "1oderate 2-3 years High Low Moderate Low High
Area 1--8oot Lake Good 2-3 years High Low low low High
Eliminated;
~rea II--near Bristo1 Good 2-3 years IHgh low low low Itigh extended
imp lemen-
I North of 180/90 Good 2-3 years High low low low Unknown tation time
\
SUPPLEMENTARY WATER SUPPLY
South Station Question- 3-6 months Moderate low low Low low
able
Bower Street Station Question- 3-6 months Moderate low low low low
ab1e E1 imi nated;
.' Mishawaka. Indiana Good 1 year to High Moderate Low Low Low unable to
18 months meet demand
.
1
I Goshen. I nd i ana Good 1 year to Itigh Moderate Low Low LOW
.! 18 months
-------
Table 2. COMPARISON OF REMEDIAL ALTERNATIVES (Continued)
Abi 1 tty
to Protect
tentative Public Health
EAT AT WELL FIELD
R DRINKING WATER
Separation
Air Stripping Good
Carbon Adsorption Good
Resin Adsorption Good
Destruction
UV-Catalyzed Moderate
Ozonation
Detoxification
Dye-sensitized Moderate
Photo Oxidation
Simple Chemical Low
Addition
Time
Required to
Implement
1 year
1 year
1 year
2-3 years
2-3 years
1 year
Relative
Cost Complexity
Moderate Moderate
Moderate Moderate
to High
High Moderate
High High
High High
Moderate Low
Ability
Environmental Community to Meet
Impact Impact Demand
Moderate Low high
Moderate Low High
Moderate Low High
Low Low High
Low Low High
Low Low Low
Result of
Initial
Screening
Consider
further
Consider
further
Consider
further
Eliminated;
unproven
technology
Eliminated;
unproven
technology
El iminated;
unproven
technology
-------
-12-
Alternative 1 -
Air Stripping
This alternative utilizes packed tower air strippers to meet the objectives
of the operable unit. Easternmost wells in Main Street Well Field are operated
as a barrier/interceptor system, capturing the contaminant plume. Contaminated
water from the wells is pumped through the air stripping towers which remove
the volatile organic chemicals (VOCs).Pumping strategies would be optinized
durin~ conceptual design. Depending on water demand, treated water from
the treatment system could be blended with water from uncontaminated wells.
The air stripping treatment system would be designed to achieve 9q.1~ removal
of trichlorethylene (TCE). Of the conta~inants frequently detected at Main
,Street Well Field, TCE is the one detected at the highest concentration,and
is the most difficult to remove with air stripping. This removal efficiency
would provide finished water at less than a 'I x 10-6 excess lifetime cancer
risk. '
Alternative 2 -
Granular Activated Carbon Adsorption
This alternative utilizes granular activated carbon (GAC) media to meet the
objectives of the operable unit. As with the previous alternative, easternmost
wells in the well field are operated as a barrier/interceptor system, capturing
the conta~inant plume. Contaminated wat~r from the wells is pumped through
contact units filled with GAC which adsorbs the VOCs. Pumping strategies
would be optimized during conceptual design. Depending on water demann,
treated water from the treat~ent system could be blended with water from
unconta~inated wells. .
The GAC adsor~tion system would likewise be designed to achieve sufficient
removal efficiencies to provide drinking water at less than a 1 x 10-6 excess
lifetime cancer risk.
Alternative 3 -
Air Stripping Followed by Granular Activated Carbon Adsorption
This alternative is a combination of the ~revious two treatment technologies.
As with the previous alternatives, easternmost wells 1n the well field are
operated as a barrier/interceptor system, capturin~ the contaminant plume.
Contaminated water is pumped through air stripping units to remove approximately
70 percent of the contamination, and then through granular activated carbon
adsorption units for removal of the vestiges of contamination. Pumping
strategies would be o~til~ized in conceptual design. Depending on water
demand, treated water from the treatment system could be blended with
water from uncontaminated wells.
As with the previous two alternatives, this treatment system would be designed
to achieve sufficient removal efficiencies to provide drinking water at less
than a 1 x 10-6 excess lifetime cancer risk.
-------
-13-
a.Selection Process
The three alternatives identified above were further evaluated in
accordance with the NCP to determine the appropriate cost-effective
remedy.
During the early stages of the alternatives review, the no action
alternative was eliminated fr~n further consideration. The decision
was based in part upon an evaluation of the health risks posed by the
presence of VOCs in the drinking water ~rovided to the City of Elkhart
by the Hain Street Well Field, and a recognition of the unlikelihood
of a natural reduction in the concentrations of these compounds in
the drinking water to or below acceptable levels.
Until the remedial investigation for the Main Street Well Field site
is completed. the complete nature and extent of the contamination of
the well field is unknown. The implementation of the appropriate
operable unit as an interim remedy will minimize and mitigate the
contamination of the drinking water provided by nain Street Well
Field and reduce the associated health threat to those dependent on
the City water supply system. Without the implementation of such a
measure, the users of the system are exposed to an unacceptable health
risk. Therefore. the no action alternative i~ not appropriate, as
discussed in greater detail previously in the Threat to Public Health
section.
As presented in Table 2. alternate water supply sources have limited
feasibility. Surface water sources would take extended time to implement.
There is no known aquifer in the area sufficiently isolated from
potential contamination. Neighboring municipal water systems do not
have sufficient existin9 surplus capacities to provide necessary
quantities. Expanding capacities at the City's other two existing
well fields has been ruled out due to questionable integrities of
the well fields. Only treatment alternatives remain from the initial
screening.
The remaining three alternatives -- air stripping. granular activated
carbon (GAC) adsorption. and air stripping followed by GAC adsorption,
-- are relatively comparable in several terms of the screening criteria
used to select the appropriate alternative for the Main Street ~ell
Field site. Table 4 summarizes the detailed comparison of the
three developed alternatives. The following criteria were utilized
in screening these alternatives: ability to protect public health.
time required to ir~plement. complexity/technical feasibility/reliability.
environnental impact. com~unity impact, ability to meet demand.
compatibility with final remedy, and relative cost. The ability to
protect public health is the criterion of primary importance, with
time required to implement closely related.
All three alternatives were developed as nearly as possible to achieve
equal removal efficiencies, and thus equal protection of pUblic
health. Nonetheless. Alternative 1 i5 slightly inferior to Alternative
-------
-14-
2 and 3 in that the air stripping process can only remove volatile
oryanic contaminants. whereas GAC adsorption also has the ability to
remove other organic contaminants. However. no such non-volatile
organic contaminants have been detected at the Main Street Well Field.
Additionally. in contrast to GAC adsorption. air stripping results in vac
emissions to ambient air. The amount of these emissions has been predicted
in the Air Management Division evaluation. The predicted increase in risk
to public health from these emissions is considered to be an insignificant
factor in selecting between the air strippiny and GAC alternatives. A
detailed analysis of this ,natter is presented in the Public Healt~ Risk
Due to Air Stripper section.
Alternative 1 is superior to Alternatives 2 and 3 in terms of time
required to implement. If design is begun in July 1985, Alternative
. 1 is the only alternative that can be comp1eted before the high demand
months of May through August 1986. Design of air stripping units is
relatively straight forward. based on influent concentration. necessary
removal efficiencies, volatility of the contaminants as expressed
by Henry's Law Constant. and air-to-water ratio. By contrast, design
of GAC adsorption systems requires operation of a pilot system for
approximately 4 to 6 months. Although the basic technology is proven,
the data base is not extensive enough to provide specific design
parameters covering all conditions and all contaminants; for applications
involving mixtures of contaminants, the only accurate method of
generating design ~arameters is to perform pilot tests on similar
mixtures. These differences in desiyn are reflected in the time
required to implement as shown in Table 5.
Alternative 1 is also slightly superior to Alternatives 2 and 3 in
terms of being a less complex treatment technology. Both air stripping
and GAC adsorption are proven technologies capable of removing the
vacs at the levels encountered at the Main Street Well Field. GAC is
more complex than air stripping because its performance is more
difficult to predict, due to variances in the organic and inorganic
content of the influent. pH, and temperature. These different
conditions found at various sites thus require pilot studies.
As in the two previous categories. Alternative 1 is slightly superior
to Alternatives 2 and 3 in terms of ability to ~eet demand. Since
Alternatives 2 and 3 require pilot studies. construction will not be
completed in time to meet 1986 SUMmer demand. After completion of
construction. all three alternatives are equal in ability to meet demand.
In terms of relative costs, Alternative 1 is an order of magnitude
less expensive than Alternatives 2 and 3, and is clearly preferable.
This is illustrated in Table 6. comparing present worth costs on a
relative basis.
The other screening criteria do not identify any significant differences
between the alternatives. No significant environmental impacts or
community impacts are expected from any alternative. All three
alternatives work towards the likely final remedial ~easure of
minimizing and mitigating groundwater contamination in the area of Main
Street Well Field.
-------
Table 4.
DETAILED COMPARISON OF REMEDIAL ALTERNATIVES
Abi1ity Compati-
to Time Complexityl Abi1 i ty bi 1i ty Result
Protect Required Technical Environ- to With Rela- of
Public to Feasibilityl mental Comunity Meet Final the Detailed
.1 ternat i ve Health Implement ReI iabU ity Impact Impact Demand Remedy Cost Screening
--
,ir Stripping Good Good Good Good Good Good Good Good
:arbon Adsorption Good Faira Fairb Good Good Fa i ra Good Poor E I imi nated ;
extended im-
plementation
time and high
cost.
lir Stripping followed Good
by Carbon Adsorption
Fa i ra
Fa i rb
Good
Good
Faira Good
Poor
E1 iminated;
extended im-
plementation
time and high
cost.
I. Will not be completed in time to meet summer 1986 demand.
). Requires pilot treatment for proper design.
-------
Design
Bidding
Construction
Total
Table 5.
TIME REQUIRED TO IMPLEMENT
Alternative 1 Alternative 2 Alternative 3
Air Stripping!
Granular Activated Gra nu la r Ca rbon
Air Stripping Carbon Adsorption Adsorption
10-12 weeks 30-32 weeks 30-32 weeks
8-10 weeks 8-10 weeks 8-10 weeks
16-20 weeks 16-20 weeks 16-20 weeks
30-42 weeks
54-62 weeks
54-62 weeks
-------
Table 6. COHPERATIVE CASH FLOW TABLE
Al ternat he 1 AHernat he 2 Alternative 3
(B) (8) (B)
(A) Shutdown (A) Shutdown (A) Shutdown
Shutdown Production (C) Shutdown Pq)duct ion (C) Shutdown Production (C)
Production and Barrier Entire Production and Barri er Entire Production and Barrier Entire
Wells Wells Well Field Wells Wells We 11 Fie I d Wel1s We 11 5 Well Field
fear (5.8 "GO) -3_f!&. "GO L (16 "GO) ~8 HGI!l (8.8 HGO) (16 HGO) (5.8 "GO) (8.8 "GO) (16 HGO)
-
° 1,106,000 1,554,000 2,320,000 4,489,000 6,435,000 11,359,000 4,316,000 6,211 ,000 11,120,000
1 158,000 208,000 319,000 1 ,611 ,000 11,525,000 18,072 ,000 3,542,000 5,353,000 5,649,000
2 158,000 208,000 319,000 1,611,000 11,525,nOO 18,012,000 3,542,000 5,353,000 5,649,000
3 158,000 208,000 319,000 1 ,611 ,000 11,525,000 18,072,000 3,542,000 5,353,000 5,649,000
4 158,000 208,000 319,000 7,617,000 11,525,000 18,012,000 3,542,000 5,353,000 5,649,000
5 158,000 208,000 319,000 7,617,000 11,525,000 18,072 ,000 3,542,000 5,353,000 5,649,000
HAL 1,896,000 2,584,000 3,915,000 42,575,000 64,060,000 101,71 q ,000 22,086,000 33,036,000 39,365,000
...--...-.- t.......". :......... ......a... ..."."-.-:8 -.......,....~. ...."~.".2 .." - - . .. S.. .. ;8""".._""-
resent
)rtha 1,705,000 2,342,000 3,529,000 33,31)3,000 50,124,000 79,866,000 17,803,000 26,563,000 32,534,000
!tathe
:05 t 5
(A) 1.00 19.6 10.4
(R) 1.00 21.4 11.3
(C) 1.00 22.6 9.22
,era 11 1.00 1.37 2.07 19.6 29.4 46.8 10.4 15.6 19.1
10 percent discount rate
-------
-18-
9. Community Relations
The Superfund activities at the Main Street Well Field site have been
followed closely and consistently by the local ~edia. Interest in
Superfund activities has been high, particularly in regard to removal
actions ongoing by the U.S. EPA in other areas in Elkhart. The pUblic,
with the exception of a few dissenters, has indicated they feel all
officials involved (City, County, State and EPA) have responded prom~tly
and properly to groundwater contam~nation in the area.
Copies of the PFS were made available to the community on June 21, 198~.
The Elkhart City Hall and Elkhart Public Library served as information
repositories. The U.S. EPA issued a press release June 21, 1985, announcing
the availability of the PFS, location of the repositories, the June 21 -
July 12 public comment period, and the July 2 public meeting at Elkhart
Central Hign School. The press release also announced a press conference
for the afternoon of July 2, 1985.
The press conference was well attended by the local newspaper, radio, and
television stations. The public meeting was well attended by the public,
as well as the above media. City, County and State officials were also
present. At this meeting, the U.S. EPA presented results of the PFS,
recolnmended air-stripping as the preferred alternative, answered 4uestions
regarding the Main Street Well Field site, and accepted public comments.
The summary of responsiveness to public comment ("Responsiveness Summary")
is attached to this narrative sUlnmary (Attachment 1).
10. Consistency with Other Environmental Laws
All three proposed alternatives are co~sistent with other Federal and
State environmental laws.
Alternatives 1 and 3 would result in the discharye of volatile organic
compounds (VOCs) into the ambient air. Indiana state law requires that
any new source causing air ernisions of less than or equal to 25 tons per
year of any regulated pollutant, such as VOCs, in excess of either 3
pounds per hour or 15 pounds per day be registered. Registration involves
sUbmitting: 1) a description of the facility including design specifications,
2) a schedule for construction, and 3) the nature and amounts of pollutants
emitted. Once the inforMation has been submitted, the Indiana State
Board of Health (IS8H) must accept the application or request additional
information. The ISBH may then impose ~nission limitations on operating
conditions if deemed necessary (Title 325, Indiana Air Pollution Control
Board, promulgdted September 23, 1981, amendments ~romulgated April 24,
1984).
The PFS evaluates estil~ates of potential air emissions from Alternatives
1 and 3. The estimated emissions were developed on a worst case basis,
assuming the same design influent concentrations as utilized to size the
air stripping towers. The evaluation of public health risk due to air
stripping performed by the U.S. ~PA Air Management Division also estimated
the ai.r emissions on a best case basis, assuming influent concentrations
based on concentrations currently detected in the well field (Attachment 5).
-------
-19-
Under worst case conditions, Alternative 1 is predicted to emit 18.1
pounds per day, or 3.3 tons per year, of volatile oryanic compounds.
Under best case conditions which are more reflective of predicted operating
conditions, Alternative 1 is predicted to emit 1.7 pounds per day, or
0.3 tons per year, of volatile organic cOMpounds.
Alternative 3 utilizes an air stripping process to remove approximately
70 percent of the VOC's before polishing the water with a GAC adsorption
system. Under similar worst case conditions, Alternative 3 is predicted
to emit 12.9 pounds per day, or 2.4 tons per year, of VOC's.
Likewise, under best case conditions Alternative 3 is predicted-to emit
1.2 pounds per day, or 0.2 tons per year, of volatile organic
compounds.
Thus, in order to provide compliance with applicable State air pollution
regulations, both Alternatives 1 and 3 will require registration under
Indiana law. Full permitting under Indiana law with the potential for
required air emission controls will not be required, even under the worst
case scenario. For exanp1e, under Alternative 1 the total influent
10adiny to the air strippers would have to increase approximately eight-
fold over the worst case analysis before air emission controls might be
required. Such an increase would represent a najor departure fron the
highest contaminant levels detected in the individual wells over the last
four years, and is not expected to occur.
Spent carbon from the GAC adsorption syst~"S in Alternatives 2 and 3 will
need to be disposed of. It is expected that the 4 to 10 million pounds
per year of spent carbon will be transported off-site for recycling for
industrial use. As a result, no special disposal requirements are expected
to result from either of the alternatives utilizing GAC.
Attachment 6 is a floodplain map of the ~ain Street Well Field vicinity
of Elkhart. Examination of the floodplain map indicates that sufficient
space exists in the well field outside both the floodplain and floodfringe
to allow construction of the treatment systems evaluated in all three
alternatives in full com?liance with applicable Federal, State, and
local regulations. Siting of the recommended alterndtive's treatment
system facilities can thus be accomplished durin~ the remedial design
in compliance with floodplain reyu1ations.
11. Assessment of Public Health Risk Due to Air Stripper
U.S. EPA Air Managenent Division performed a health risk assessment tQ
evaluate the health risks which could arise from the emission of the
contaMinants as air pollutants if the air stripping technology is
implemented as outlined in Alternative 1. The health risk assessment was
conducted for predicted air emissions for both worst case and best
estimate scenarios as described above in the Consistenci with Other
Environmental Laws section assuming: 1) influent water flows with
contal1inant concentrations equal to design concentrations (worst case
-. ~ ,... ..~ ...
-------
-20-
evaluation), and 2) influent water flows with contaminant concentrations
at current levels (best estimate evaluation). The melnorandum summarizing
the results and conclusions of this risk assessment is attached (Attach-
ment 5).
As indicated above, the worst case evaluation is based on design influent
concentrations, which were developed based on mass balance using the highest
concentrations detected in each well previous to the City's implementation
of barrier wells. Current concentrations are at least an order of
magnitude less. Thus, the best estimate, which uses the current
concentrations as its basis, is the appropriate evaluation to consider.
The results of the air risk assessment therefore indicate that the public
health risk due to air emissions from an air stripper as proposed
in Alternatives 1 and 3 are of little significance.
Based on the results of the air risk assessment,
that no treatment of emissions to ambient air is
air stripping systens proposed in Alternatives 1
further minimize public health risks.
it can be concluded
necessary for the
and 3 in order to
12. Recommended Alternative
Tne National Oil and Hazardous Substances Contingency Plan (NCP) [40 CFR
Part 300.68(j)] states that the appro~riate extent of remedy shall be
determined by the lead agency's selection of the remedial measure which
the agency determines is cost-effectivp. (i.e., the lowest cost alternative
that is technologically feasibJe and reliable and which effectively
mitigates and minimizes damage to and provides adequate protection of
public health, welfare, or the environ~ent). Ra~ed on the evaluation of
cost and effectiveness of each proposed alternative, the comments received
from the public and the Indiana State Board of Health, and the State and
Federal environmental requirements, Alternative 1 has been determined to
be the cost-effective alternative.
The recommended alternative is considered an operable unit remedial
action. Operable units are similar to initial remedial measures
(IRM's) as defined in Section 300.68(e)(1) of the current NCP.
This operable unit remedial action for provision of an alternate water
supply is ap~ropriate because there is contamination of drinking water at
the tap. The objective of this action is to provide those consumers
currently dependent on Main Street Well Field for drinking water with a
reliable supply of safe, potable water until the final remedial measure(s)
may be implemented. The RIfFS to begin in the fall of 1985 will exami.ne
appro~riate final response action(s).
Tne recommended alternative provides for ~acked tower aeration treatment
for 5.8 MGD of contaminated groundwater. This capacity represents the lost
capacity of the well field due to the shutdown of five contaminate~ wells.
The recomnended alternative would be designed and constructed to allow
-------
-21-
flexibility in which wells to treat. Pumping strategies will be optiMized
during conceptual design. The packed tower air stripping system would be
designed to achieve 99.1 percent removal of trichloroethylene(TCE), the
critical contaminant, and would consist of three packed tower units.
This removal efficiency would provide drinking water at less than a
1 x 10-6 excess lifetime cancer risk. The air stripping treatment system
would be designed to treat water with influent VOC concentratiQns based
upon the highest concentrations of contaminants detected individually in
each of the wells to be treated. Performance of the air stripping treatment
system would be frequently monitored to asure that removal efficiencies
required to protect public health are consistently achieved.
Main Street Well Field operates at or below this 5.8 MGD capacity 82.5
percent of the time, as shown in Table 7. Water necessary to meet
additional demand would be pumped from uncontaminated wells and blended
with the air stripped water. With four wells with concentrations
currently below detection limits, a combined capacity of 9.8 MGD of
clean water can be achieved. Main Street Well Field operates at or
below this capacity 98.2 percent of the time. Three other wells
with concentrations currently just above detection linits can be utilized
to meet maximum daily demand.
If required rel110val efficiencies are not being achieved, the pumping
strategy could be rapidly altered. The seven wells mentioned above
could be pumped to meet average daily demand. Water from the air
stripping system could be blended with their capacity as necessary to
~eet higher demands. When not needed for that purpose, the output
from the air stripping syste," could be discharged to Christiana Creek.
At such til:'le as full implementation of this contingency plan becomes
necessary, piping changes and NPDES permitting would be necessary.
The capital cost of this alternative is estimated to be S1,106,000. The
operation and maintenance (O&M) costs are estimated to be S158,000 per
year for electric power and operating labor. The five-year present worth
cost for the recommended alternative is S1,896,000. All these figures
are accurate to +50/-30 percent at this time.
It is recommended that the U.S. EPA fund 90 percent of the O&M costs for
a period not to exceed one year after cOf'llpletion of construction. The
State of Indiana will provide the 10' O&M match for the first year and
will assume all OIM for the life of the project. The U.S. EPA will fund
90' percent of the capitol costs, and the State of Indiana will fund the
remaining .10% of capital costs.
13. Recommended Alternative as it Relates to Final Remedy
Operable units are analagous to initial re!ned1al measures (IRM's) as
defined in Section 300.68(e)(1) of the current NCP. Currently, the Main
Street Well Field supplies drinking water to over 37,000 residents. The
. ~ ; '1 ','" ....,., .
-------
Table 7.
Main Street Well Field
Pumpage Data.
Average Daily DeMand
Daily Demand during
Maximum r~onth
6.5 MGO
Maximum Daily Demand
8.8 MGD
13 .0 MGD .
Frequency Distribution
Cumu 1 at ive
Pumpage,MGD Frequency, , Frequency, ,
less than 3 9.0 9.0
3-4 15.9 24.9
4-5 29.9 54.8
5-6 27.7 82.5
6-7 4.4 86.9
7-8 4.1 91.0
8-9 3.n 94.6
9-10 3.6 98.2
10-11 0.8 99.0
more than 11 1.1 100.1
NOTES
Data based on highest recorded purnpage frQiUres, 1974
. through 1984.
-------
-23-
residents are exposed or are potentially exposed to a variety of VOCs
from the contaminated ground water. These compounds are suspected
carcinogens as described previously in the Toxicity of Pollutants section.
A final remedy at this site can be approached by two means. minimization
and mitigation of groundwater contamination. and use of an alternative
water supply. Although the final ~emedy 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 less likely that the final remedy will be an alternate water supply
source. .
Attachment 4 chronicles numerous incidents of groundwater contamination
in the Elkhart area. This chronicle and the PFS indicate that the Elkhart
area relies on a very vulnerable aquifer for its drinking water. The
aquifer is a very porous and productive one. consisting of sand and gravel
in deposits very close to the surface. Topsoils provide no protective
barrier against contaminant intrusion. Subsurface protection at best is
minimal due to finger-like clay deposits.
Hai n St reet Well Fi e 1 d is the largest of three Ci ty well fi e 1 ds. The
City's other two well fields are likewise vulnerable. South Station Well
Field is located in proximity to a site of known groundwater contamination
by YOCs. Bower Street Well Field is located in an area where shallow
residential wells have shown VOC contamination. and its wells have
sporadically shown detectable levels of YOCs. The integrity of these
well fields as supplements to the production capacity of Hain Street Well
Field is thus questionable.
Ongoing U.S. EPA removal actions in Elkhart are defining the extent of
groundwater contaminant plumes in the Elkhart area. These actions have
already led to limited number of hook-ups of some residents to the City
water system while numerous other affected residents are being provided
bottled water. Serious contamination on a ~,idespread basis could result
in a large number of additional hook-ups to the City water system.
Consequent increased water demands would further stress well field
performances.
The recommended alternative seeks to provide consumers currently dependent
on Main Street Well Field for drinking water with a reliable supply of
safe. potable water. By appropriately selecting wells in the contaminant
plume. plume migration can be managed to prevent further deyradation of
t~e well field. Thus it is likely that the air stripping treatment sy'stem
will be incorporated into a final remedy selected as part of a minimization
and mitigation of groundwater contamination. depending on results of the
RIfFS.
Treatment and source control are two categories of technologies to address
minimization and mitigation of groundwater contamination. It is likely
that the final remedy will be either a treatment remedy in combination
with source control or standing alone. The air stripping system could be
part of either of these final remedies.
-------
-24-
In the event that the RIfFS identifies limited localized sources of
contamination. the air stripping treatment system could be utilized to
treat contaminated groundwater in conjunction with source control measures
implenented upyradient as the final remedy. In the event that aquifer
contamination is extensive and dilute. source control may not be a viable
alternative. Treatment of the aquifer. utilizing the air stripping system
with necessary supplements for other types of contaminants or increased
capacities. may then be the only means to minimize and mitigate groundwater
contamination as a final remedy.
Final remedies at the Main Street Well Field site ~hich do not include
minimiziny and mitigating groundwater contamination appear unlikely at
this point. Alternate water supply s~urces have limited feasibility.
There is no known aquifer in the area sufficiently isolated from potential
contamination. Neighboring municipal water syst~ns do not have sufficient
existing surplus capdcities to provide sufficient quantities. Expanding
capacities at the City's other two well fields has been ruled out due to
questionable integrities of the well fields. Therefore. the final remedy
will likely include minimizing and mitigating groundwater contamination.
Although the air stripping system will not singularly eliMinate contaMination
of the well field aquifer. this operable unit will minimize the threat
posed by that contamination until such time as a final remedy is selected
by the U.S. EPA and implemented. Until the extent and degree of groundwater
contamination is evaluated by the RIfFS. it is not technically feasible
to develop a cost-effective, long term remedy for the site.
Thus, the operable unit will effectively meet two U.S. EPA goals, achieving
the primary goal of limiting exposure to a significant (potential) health
threat by providing safe potable drinking water to those currently
dependent on the Main Street Well Field, and also effectively working
towards the likely final re~edy of mini'1izing and mitigating groundwater
contamination at the Main Street Well Field.
14. 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 relnedial 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 Elkhart owns and operates the well field. the Agency
does not currently possess any information to support a finding that the
City of Elkhart owned the well field at the time of any disposal of
hazardous substances. In fact, due to the nature of the contamination
i.e.. groundwater cJntamination. U.S. EPA does not currently possess any
information to support a finding that any hazardous substances were
dis~osed of on the well field. It is probable that the source(s) of
contamination lies beyond the property boundary of the well field. There-
fore. this site is currently subject to the 10~ match to Federal Superfund
monies spent at this site.
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Tne State of Indiana Health Commissioner has sent the Region V Regional
Administrator a letter acknowledging the State financial obligations in
this remedial action.
The operation and maintenance (O&M) costs will be covered under a State-
Superfund Contract between the State and U.S. EPA at the completion of
design of the o~erable unit.
15. Schedule
The REM II contractor, Camp Dresser & McKee (CD~), will manage the
design of the operable unit. The U.S. Army Corps of Engineers
(USACE) will procure the construction contractor and oversee con-
struction activities. The schedule for design and construction
activities is as follows:
lAG with USACE-MRD for Technical
Assistance during Pre-Design
COM submits draft Pre-Design Report
6/17/85
7/29/85
Approval of Remedial Action
(Sign ROD)
7/31/85
COM subnits draft Design Work Plan
7/31/85
lAG with USACE-MRD for Technical
Assistance during Remedial Design
Preliminary design (30~) and cost
estimate (+30~, -15~) complete
7/31/85
8/2/85
Preliminary design review meeting
with [PA, State, and USACE
Preliminary design and cost approval
by USACE
8/12/85
8/12/85
Pre-final design (95~) and cost
estimate (+15~, -10~) complete
9/6/85
Pre-final design review meeting
with EPA, State, U~ACE
9/12/85
Pre-final design and cost estimate
approval by USACE
9/12/85
Advance Notice to Prospective Bidders
in Co~erce Business Daily
9/13/85
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lAG with USACE-MRD for Remedial Action
(Advertising and Award, Construction
Oversight)
9/13/85
Indiana Environmental Management Board
Meeting - State Superfund Contract approval
9/20/85
. Remedial Action Obligation
Final Design Complete
9/20-23/85
9/23/85
State Superfund Contract Signed
by EPA
9/24/85
9/30/85
Advertise for Competitive Bids
Contract Award
10/30/85
11/15/85
Open Bids
Notice to Proceed
11/30/85
Estimated Construction Period
16-20 weeks
Construction Complete
March - April 1986
16. Future Actions
An RIIFS for the full remedy will be underway this fall. The workplan
for the RIIFS will be initiated subsequent to ROD signature. Sub-
mission of the RIIFS workplan is projected for late Septelnber or
October 1985. Objectives of the RIIFS are to determine extent of
contamination, determine hazard potential, and evaluate potentially
feasible remedial action. The feasibility study will recommend the
most cost-effective remedial action{s) for the site. Information
gathered during EPA removal actions in Elkhart will allow refinement
of the RIIFS, and may suggest additional operable units to be pursued
through a phased approach. At present, source control measures seem
prudent as the next operable unit.
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