United States
Environmental Protection
Agency
Office of
Emergency and
Remedial Response
PB93-964106
EP AIROD/R05-921209
September 1992
&EPA
Superfund
Record of Decision:
Clare Water Supply, MI
Hazardous Waste CoUecfion
~sformEPAatRion Resource Center
agion 3
Phnadelphfa" PA 79107
u. s. Envifoornelltt~ ProtectiM Agency
Region 111 Hazardous Waste
TeChnicat Information Center
841 Chestnut Street. 0" RoM
~. PA 191 .~
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c
NOTICE
The appendices listed in the index that are not found in this document have been removed at the request of
the issuing agency. They contain material which supplement. but adds no further applicable information to
the content of the document. All supplemental material is, however, contained in the administrative record
for this site.
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o
50272 101
.
REPORT DOCUMENTATION 1" REPORT NO. 1 ~ 3. AeclpIeiIt'a A_on No.
PAGE EPA/ROD/R05-92/209
4. TI1I8 - 8ub1I1I8 5. II8port D8t8
SUPERFUND RECORD OF DECISION 09/16/92
Clare Water Supply, MI
6.
Second Remedial Action - Final
7. A""'or(a) 6. IWfonnlng OrgenlDtion R8pI. No.
8. P8rtonnlng OrgelnlDtion - - Add.... 10. Ptoj8ctlTuklWorI< Unit No.
11. ContnIct(C) or Gr8Rl(G) No.
(C)
(G)
1~ ~orIng OI'ganlz8tlon - - -- 13. Type 01 Report 6 PerIod Co-
U.S. Environmental Protection Agency 800/000
401 M Street, S.W.
Washington, D.C. 20460 14.
15. Supplemenlllty No'"
PB93-964106
16. Abetract (Umlt: 2110 wolde)
The Clare Water Supply site is a municipal well field in the City of Clare, Clare
County, Michigan. Land use in the area is predominantly commercial, industrial, and
residential with wetlands neighboring the site. In addition, a drainage ditch runs
through an industrial area directly northwest of the site across the well field,
discharges into the wetlands, and recharges the underlying aquifer. An estimated
3,300 residents of Clare use the municipal water supply as their drinking water supply.
In 1981, state investigations of the municipal wells showed VOC contamination in the
ground water. In 1982, soil samples taken during the installation of monitoring wells
showed soil contamination from seven industrial facilities bordering the well field and
attributed contamination of the shallow perched aquifer to the leaching of contaminants
from these areas. A 1990 interim action ROD for the site provided for air stripping to
remove VOCs from the city's water supply. The air strippers were installed and began
operating in 1991. This ROD addresses the contaminated soil and ground water as a
final remedial action for the site. The primary contaminants of concern affecting the
soil and ground water are VOCs, including benzene, PCE, TCE, and xylenes.
(See Attached Page)
17. Docum8nt """'yela .. D88criplO18
Record of Decision - Clare Water Supply, MI
Second Remedial Action - Final
Contaminated Media: soil, gw
Key Contaminants: VOC (benzene, PCE, TCE, xylenes)
b. Idotntifi8r8lOpen-End8d T......
c. COSATI FI8IdIG,-
18. Avllllabiity St8I8m8nt 18. Security CIa.. (Thla Report) 21. No. 01 Pagea
None 54
20. Security CIa.. (Thla Page) tt PrIce
Non~
Ut' IIUNAL
(Sea ANSl-Z38.18)
Sea InarrutUona on ReveIW
(Formerly NTlS-35)
Department 01 Commerce
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EPA/ROD/R05-92/209
Clare Water Supply, MI
Second Remedial Action - Final
Abstract (Continued)
The selected remedial action for this site includes treating 54,800 cubic yards of soils
by implementing institutional controls, constructing an in-situ vapor extraction (ISVE)
system to remove VOCs from soil and sediment; constructing ground water extraction wells,
treating contaminated ground water by UV/chemical oxidation, and reinjecting treated
ground water into the aquifer. Air emissions from the ISVE will be treated by granular
activated carbon (GAC) filters, which will be regenerated offsite. The total present
worth cost is estimated at $11,754,247, including an average annual O&M cost of $431,183
over a 30-year operational period.
PERFORMANCE STANDARDS OR GOALS: Chemical-specific soil clean-up goals are based on
protection of ground water and include benzene 20 ug/kg; vinyl chloride 0.4 ug/kg; TCE
60 ug/kg; PCE 14 ug/kg; methylene chloride 100 ug/kg; tranS-1,2-DCE 2,000 ug/kg;
cis-1,2-DCE 1,400 ug/kg; xylenes 6,000 ug/kg; toluene 20,000 mg/kg; ethylbenzene
1,000 mg/kg; 1,1-DCA 14,000 mg/kg; 1,2-DCA 8 mg/kg; 1,1,2-TCA 12 mg/kg; 1,1,1-TCA
4,000 mg/kg; and styrene 20 mg/kg. Chemical-specific ground water clean-up goals are
based on SDWA MCLs, and state MCLs under Michigan's Act 307 Type B Cleanup Levels and
include benzene 1 mg/l; vinyl chloride 0.02 mg/l; TCE 3 mg/l; PCE 0.7 mg/l; methylene
chloride 5 mg/l; trans-1,2-DCE 100 mg/l; cis-1,2-DCE 70 mg/l; xylenes 300 mg/l; toluene
800 mg/l; ethylbenzene 70 mg/l; 1,1-DCA 700 mg/l; 1,2-DCA 0.4 mg/l; 1,1,2-TCA 0.6 mg/l;
1,1,1-TCA 200 mg/l; and styrene 1 mg/l.
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RECORD OF DECISION
FOR THE SECOND OPERABLE UNIT
AT
THE CLARE WATER SUPPLY SITE IN
CLARE COUNTY, MICmGAN
September 16, 1992
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DECLARATION FOR THE RECORD OF DECISION
SITE NAME AND LOCATION
Clare Water Supply Site
Clare, Michigan '
STATEMENT OF BASIS AND PURPOSE
This decision document presents the United States Environmental Protection Agency's (U.S. EPA's)
selected remedial action for the Clare Water Supply site located in Clare, Michigan. The remedial action
was selected in accordance with the Comprehensive Environmental Response, Compensation, and Liability
Act of 1980 (CERCLA), as amended by the Superfund Amendments and Reauthorization Act of 1986
(SARA), and, to the extent practicable, the National CODtingency Plan (NCP). This decision is based
upon information and documents contained in the administrative record for this site.
The State of Michigan Department of Natural Resources concurs with the selected remedy.
ASSESSMENT OF THE SITE
Actual or threatened releases of hazardous substances from this site, if not addressed by implementing the
response action selected in this decision document, may present an imminent and substantial endangerment
to public health, welfare, or the environment.
DESCRIPTION OF THE SELECTED REMEDY
This response action addresses remediation of soil and groundwater contaminated with Volatile Organic
Compounds (VOCs) at the Clare Water Supply Site. The principal threats posed by conditions at the Site
include ingestion, inhalation, and dermal absorption of VOCs through use of supplied water and contact
with contaminated soils. The selected remedy will eliminate these threats.
The major components of the selected remedy include:
1)
In-Situ Vapor Extraction of Volatile Organic Compounds (VOCs) from contaminated soil areas;
2)
Extraction of contaminated groundwater, treatment using Ultraviolet Photochemical Oxidation,
and reintroduction of treated groundwater into aquifer system.
ST A TIITORY DETERMINATIONS
The selected remedy is protective of human health and the environment, complies with Federal and State
requirements that are legally applicable or relevant and appropriate to the remedial action or meets the
conditions necessary to justify a waiver of such requirements. and is cost-effective. This remedy utilizes
permanent solutions and alternative treatment or resource recovery technologies to the maximum extent
practicable and satisfies ~e statutory preference for remedies that employ treatment that reduces toxicity~
mobility, or volume as a principal element. Because this remedy will result in hazardous substances
remaining on-site above health-based levels, a review will. be conducted within five years after
cozenc ent of remedial action to ensure that the remedy continues to provide adequate protection of
human h th and the envi nment.
t , . gj(:fr2.
Valdas V. A . Date
Regional Admini
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STATE OF MICHIGAN
NAtURAL AE8OURClI8
CC)I8I188ION
LAIUIV DeVUYST
PAUL IISILI
GORDON I. GUY!R
JAMla P.IIU
DAVID I40LLI
O. anWAR' MV'RS
.IOIV Y. PANO
8
JOHN ENGLER. Governor
DEPARTMENT OF NATURAL RESOURCES
Sine", T. Ma80" .~ud"'91 '.0.80)1 .a00Z8. L8nsl"9, .., ...~
IIOLMD HAllllei. Dlreclor
September 16, 1992
Mr. ~a1das V. Adamkus, R-19J
Adm11istrator, Region 5
U.S. Environmental Protection Agency
77 W~st Jackson Boulevard
Chicago, Illinois 60604-3590
Dear Mr. Adamkus:
The Michigan Department of Natural Resources, on behalf of the State of
Michigan. has reviewed the proposed Record of Decision (ROD) for the Clare
Water Supply Superfund site. Clare County, Michigan, which we received on
September 8, 1992. We are pleased to inform you that we concur with the
remedy outlined in the draft ROD for the site.
The major components of this remedy include:
*
Institution of deed and/or access restrictions as necessary.
Diversion of the US-lO drainage ditch around contaminated sediments
while the remedial action is being conducted.
.
*
50i1 vapor extraction of volatile organic compounds from contaminated
soil areas. .
.
Extraction of contaminated groundwater and treatment using the
ultraviolet photochemical oxidation system.
Discharge of treated groundwater to injection wells located upgradtent
of the site. or to the Clare POTW. or to the Tobacco River.
*
*
Regular monitoring of system performance.
The State of Michigan also concurs with the analysis of legally applicable or
relEvant and appropriate requirements contained in the Statutory
QW.rminat ions sect ion of the ROD.
.. 1028
2m
.
C
'"II
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---~ --~ - --. -
---- ---.--
~ - I. -.} - - ....... - ~
Mr. \'a 1 das V. Adamkus
-2-
".... . ""...., , . ""-
September 16. 1992
If YCIU have questions regarding this site, please contact Mr. Brady BOYCI,
Supew'fund Section, Environmental Response Division, at 517-373-4824. or you
allY c:ontact me.
cc: Mr. James Mlyka, EPA
Mr. Jon Peterson, EPA
Mr. Alan J. Howard, MOHR
Mr. WilHam Bradford, MOHR
Ms. Denise Gruben, MOHR
Mr. Brady Boyce. MOHR
Sincerely,
Russell J. Harding
Deputy Director
517-373-7917
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I.
II.
III.
IV.
V.
VI.
VII.
VIII.
IX.
X.
XI.
XII.
1.
2.
3.
4.
5.
6.
7.
TABLE OF CONTENfS
SITE LOCATION AND DESCRIPTION
SITE mSTORY AND ENFORCEMENT ACTIVrnES
COMMUNITY RELATIONS HISTORY
SCOPE AND ROLE OF OPERABLE UNIT
SITE CHARACTERISTICS
SUMMARY OF SITE RISKS
REMEDIAL ACTION OBJECTIVES
DESCRIPTION OF REMEDIAL ACTION ALTERNATIVES
EVALUATION OF ALTERNATIVES
THE SELECTED REMEDY
STATUTORY. FINDINGS
RESPONSIVENESS SUMMARY
LIST OF FIGURES
SITE LOCATION
MAP SHOWING LOCATION OF SOURCE AREAS
1
2
5
5
6
11
15
20
26
33
40
(following) 47
3
9
LOCATION OF GREATER THAN RULE 57 LEVELS IN GROUNDWATER 19'
SOIL VAPOR EXTRACTION AREA AT EX-CELL-O PROPERTY
35
SOIIlSEDIMENT VAPOR EXTRACTION AREA - MITCHELL PROPERTY 35
~OIL VAPOR EXTRACTION AREA - STANDARD OIL SITE
GROUNDWATER EXTRACTION & TREATMENT LAYOUT
36
36
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1.
2.
3.
4.
5.
6.
7. .
8.
9.
10.
LIST OF TABLES
MAX. CONTAMINANT LEVELS IN EACH SOURCE AREA
CONTAMINANT CONCENTRATION RANGES IN EACH MEDIA
CARCINOGENIC & NONCARCINOGENIC RISK SUMMARY
CLEANUP ACTION LEVELS FOR GROUNDWATER & SOIL
RULE 57 DISCHARGE LIMITS MORE STRINGENT THAN TYPE B
OCCURRENCES OF GREATER THAN RULE 57 CONCENTRATIONS
REMEDIAL ACTION ALTERNATIVES & COST SUMMARY
CAPITAL COST FOR COMBINATION ALTERNATIVE
OPERATION & MAINTENANCE COST BREAKDOWN
PRESENT WORTH COST ANALYSIS
10
12
13
17
18
19
21
37
38 .
39
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DECISION SUMMARY
SITE NAME, IDCATION, AND DESCRIPTION
The C are Water Supp y IS In the southwestern qua rant 0 the CIty 0 Clare, MIchIgan; In
the southeast 1/4 of Section 34, Township 17 North, Range 4 West of Grant Township,
Clare County, Michigan. The Clare Water Supply system withdraws groundwater from four
municipal wells (MW) in the area, each tapping an unconsolidated sand aquifer which occurs
between approximately 30 to 80 feet below the surface. Two of the wells, MW #2 and MW
#5, are located in the northeastern portion of the site. Based on sampling since 1981, these
wells have been shown to be contaminated. The contaminants in these wells consist .
primarily of chlorinated hydrocarbons. Two uncontaminated wells, MW #6 and MW #7, are
located generally south and southwest of the contaminated portion of the site, respectively.
The Clare Water Supply is the Public Water Supply for the 3,300 residents of Clare,
Michigan. This has been found to be the only feasible source of drinking water for the
community.
West of the contaminated wells, approximately 14 manufacturing and retail businesses are
operating. It appears that several of these facilities may be or have been the location of
contamination source areas. Current or past operations which contributed to the
contamination include lagoon disposal, underground and above ground tank storage, and
drain tile discharges from two of the facilities.
The site is generally bounded to the north by 5th Street (U.S. Highway 10). The western
boundary of the site roughly corresponds to the western side of the Mitchell Property, and
the well field is bounded to the east by Maple Street (Figure 1). The Ann Arbor railroad line
traverses the site from the south to north and the C&O Railroad line crosses the site at the
northwest edge. The Little Tobacco Drainage ditch flows across the wellfield entering from
the southern border of the industrial area located directly west-northwest of the municipal
wellfield. The drainage ditch is spring fed before it enters the industrial area and receives
input from surface runoff. The flow in this drainage ditch is intermittent and it rarely
exceeds a few inches in depth. The drainage ditch empties into a small wetlands area which
directly recharges the aquifer in the vicinity of the two contaminated wells.
The site soils create two different hydrologic regimes within the investigation area. The first
hydraulic regime consists of a perched water zone created by the low-permeability clay/till
unit(s) in the western half of the site. The second is created by aquifer sand underlying till.
The aquifer is 20 to 40 feet thick in a sand unit beginning at 30 to 40 feet below the ground
surface. In the western, industrialized portion of the site, 30 to 40 feet of clay and glacial
till cover the aquifer. In the eastern well field portion of the site, the aquifer sand joins a
thick sequence of river channel sands which extend from the ground surface to approximately
80 to 90 feet below ground surface, based on drilling logs.
Flow from the drainage ditch infiltrates the soils at the western edge of the well field. On
. the eastern edge of the wellfield, surface flow from the Little Tobacco drainage ditch joins
the Little Tobacco River and continues eastward. Other local surface water includes the
Tobacco River, approximately one-half mile north of the well field, and Shamrock Lake,
approximately 1 mile northeast of the well site.
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~
SITE HISTORY AND ENFORCEMENT ACTIVITIES
~
In December, 1981, the Clare municipal wells were sampled by the Michigan Department of
Public Health (MDPH) for organic compounds. The sampling revealed Volatile Organic
Compound (VOC) contamination in MW #2 and MW #5. The contaminants were identified
as chlorinated hydrocarbons and included trichloroethene (TCE) and dichloroethene (DCE).
The MDPH determined that the aeration process which the city used to remove iron from the
drinking water and blending of the water from the contaminated wells (MW #2 and MW #5)
with water from the uncontaminated well (MW #6) would effectively reduce the
contamination in the water prior to distribution.. Testing results indicated that the iron
removal aeration treatment removed approximately 67% of the TCE contamination through
volatilization during the forced draft aeration (45 parts per billion (Ppb) before treatment, 15
ppb after treatment). DCE concentrations were not significantly affected by the aeration (11
ppb before treatment, 10 ppb after treatment). Blending of water from the least contaminated
wells facilitated a further reduction in contaminant concentrations within the tap water
system. Water was aerated and blended in this manner before delivery until completion. of
the interim action operable unit which has provided for air stripping of all water pumped
from MW #2 and MW #5 since March 7, 1991.
Well log data from a 1982 monitoring well drilling program conducted by the Technical
Assistance Team (TAT), a contractor working on behalf of the U.S. EPA, established the
existence of clay lenses that covered the area west of the municipal wellfield. Soil samples
from the industrial area indicated grossly contaminated soils near at least four industrial sites.
This short-term study indicated that the major sources of soil and groundwater contamination
were most likely located directly west of the well site in the industrial area. Contaminants
are believed to be leaching out of soils on the industrial properties, entering a shallow
perched aquifer, and migrating to the deeper aquifer that serves the municipal wellfield.
Contaminants appear to be transported by both surface water (the drainage ditch) and
groundwater flow pathways.
In November 1982, the Clare site was evaluated using the Hazard Ranking System (HRS)
and was then proposed to Group 7 of the National Priorities List (NPL). The site was listed
as final on the NPL on September 21, 1984.
In September 1984, the MDNR requested that a Remedial Investigation/Feasibility Study
(RIlFS) for the Clare Water Supply be initiated in fiscal year 1985. Concurrent to this
request, a short-term hydrogeologic investigation was conducted by the MDNR. The
objective of the MDNR's study was to identify potentially responsible parties (pRPs) so that
they could be requested to undertake the RIlFS.
2
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1/2
,
2000
o
,
3000
1 Mil.
1000
o
1000
i
40 0
5000
6000
7000 Feet
FIGURE 1
POOR QUALITY
ORiGiNAL
CLARE WELL FIELD RifFS
CLARE. MICHIGAN
U.S.G.S. QUADRANGLE HAP
7, ~INUTE SERIES(TOPOGRAPHIC)
CLARE, MICHIGAN
PROVISIONAL EDITION 1983.
R-4-w: BETwEEN T-16N AND T-17N.
SITE LOCA TJON MAP
\
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On September 27, 1985, a Consent Order was signed, binding the U.S. EPA and the PRPs:
Colt Industries (now Coltec), Ex-Cello Corporation, Ransburg Corporation, and United
Technologies Automotive, to complete a RI/FS at the Clare Water Supply field in Clare,
Michigan. The Remedial Investigation (RI) was initiated in September, 1988.
From September 6, 1988 to November 12, 1988, the following Phase I field work was
completed by the PRPs: installation of 24 shallow (5-7 feet deep), 11 intermediate (18-47
feet deep), and 4 deep (55-105) groundwater monitoring wells; completion of 41 soil borings;
collection of 6 sediment and 12 surface water samples from the Little Tobacco Drainage
Ditch; sampling and measuring water levels of all ground-water monitoring wells; and
geophysical surveys. This field work was designed to identify the sources of the
contaminants, determine the vertical and lateral extent of contamination, locate contaminarit
migration pathways, and evaluate the public health and environmental risks associated with
the site. .
Phase II of the Remedial Investigation (RI) field work was conducted from June 13, 1989 to
August 16, 1989. Field activities during this period included geophysical surveys, 4
additional shallow ground-water monitoring well installations, 6 additional intermediate depth
groundwater monitoring well installations, 10 soil borings, drain tile investigations with 14 .
test pits, 6 piezometer installations, a 72 hour pump test of the aquifer serving the wellfield,
sampling of ground water, 5 surface water samples from the drainage ditch and ground water
level measurements.
Interim Action
The sampling results obtained from the RI field work indicated that the levels of
contaminants in the water supplied to consumers were approaching or equal to the Maximum
Contaminant Levels (MCLs). Consequently, U.S. EPA prepared an Interim Action Record
of Decision (ROD) in August of 1990 to provide wellhead treatment of the water supply until
the RI/FS was completed and the overall site remedy implemented. The ROD selected air
stripping of the city water supply as the preferred remedy for the interim action. The air
strippers were installed and began operating in March of 1991 and are removing over 90 % of
the volatile contaminants from the City's water supply.
Remedial Investigation / Feasibility Study
A Remedial Investigation (RI) Report prepared by the PRPs was submitted in October of
1990. The results of this report are summarized below in the section entitled "Summary of
Site Characteristics". A Feasibility Study (FS) prepared by the PRPs was submitted in
February of 1992. The Feasibility Study (FS) submitted in February of 1992 was modified
for clarity by U.S. EPA and released in May of 1992. The FS report evaluates a no action
alternative, two minimal action alternatives involving the use of institutional controls and/or
containment, two treatment alternatives for contaminated soil and two treatment alternatives
for contaminated groundwater.
4
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COMMUNITY PARTICIPATION
A fact sheet outlining the RI sampling program was distributed in August of 1988. An RI
initiation public meeting was also held at that time in Clare. U.S. EPA issued a Proposed
Plan for the Interim Action Operable Unit (Protection of City Water Supply) in June of 1990
and held a public meeting to solicit public comments on U.S. EPA's plan to have an air
stripper installed on the City Water Supply in july of 1990. U.S. EPA held a public meeting
in January 1991 to explain that the RI report had been made available for public review and
to reveal the general results of the RI. The Feasibility Study (FS) and the Proposed Plan
were both issued to the public on May 26, 1992.
All of the above documents, including the analytical data, are available in both the
administrative record and the information repository maintained at the Garfield Memorial
Library at 4th and McEwan Streets in Clare.
To elicit public comments on the USEPA's Proposed Plan and the other remedial alternatives
evaluated in the FS, a comment period was held from May 27, 1992 through June 25, 1992.
In addition, U.S. EPA held a public meeting on June 3, 1992 at 7:00 p.m. at Clare City Hall
to present the alternatives evaluated in the FS and describe the combination of remedial
alternatives presented in the Proposed Plan for this action. All comments which were
received by EP A prior to the end of the public comment period, including those expressed
verbally at the public meeting, were considered in making the final decision and are
addressed in the Responsiveness Summary at the end of this Record of Decision.
"
SCOPE AND ROLE OF RESPONSE ACTION WITHIN SITE STRATEGY
U.S. EPA has organized this project into two operable units: The first operable unit was an
interim action to address contamination of the drinking water supply by Trichloroethene
(TCE) and TCE-degradation products (Record of Decision date August 18, 1990). The
interim action provides wellhead treatment in order to maintain a safe drinking water supply
and will continue as long as the levels of contaminants in the untreated supplied water equal
or exceed any Maximum Contaminant Level (MCL). .
The U.S. EPA has identified the principal threat to human health and the environment at the
Clare Water Supply Site to be the contaminated soil areas shown in Figures 4, 5, and 6
which will be addressed in the second operable unit covered by this Record of Decision
(RO~). The contaminated soil is the major remaining source of groundwater contamination.
The selected remedy is anticipated to be the final remedial alternative to be implemented at
the site unless other sources are identified. The groundwater plume and contaminated soils
will be treated in accordance with applicable or relevant and appropriate requirements of
Federal and State law. In addition, the U.S. EPA considers treatment of the contaminated
soil, which is the source of groundwater contamination and is a principal threat, to be the
most practicable remedy at this time.
5
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A third operable unit may be necessary to address other potential source areas should they be
identified. The results of the RI suggest that there may be other source areas contributing to
the groundwater contamination at the Clare Site. The owners or operators of several
businesses in the vicinity of the well field were contacted by U.S. EPA and asked to provide
information concerning their use and disposal of solvents and/or cutting oils. The
information supplied by these individuals did not confirm or deny that they represent
additional sources of contamination. Further investigation and sampling will be conducted to
determine if there are additional source areas present at the Clare Water Supply Site. If
additional source areas are identified, they will be addressed by a third operable unit.
SUMMARY OFSlTE CHARACTERISTICS
The Remedial Investigation prepared by the PRPs broke the Clare Water Supply Site up into
seven (7) areas. Each of the 7 areas were named for the major industrial facility within that
area that was thought to be a source of contamination based upon earlier investigations
conducted by the U.S. EPA and MDNR. The location of each of these 7 areas within the
well field is shown on Figure 2. Soil, groundwater, sediment and surface water samples
were collected and analyzed during the RI. The maximum levels of contaminants found in
soil and/or groundwater within each of the 7 areas is listed in Table 1. The RI report
contains all of the detailed analysis results for each well or boring in each of the 7 areas.
MITCHELL AREA: Two lagoons were formerly located on the south side of the Mitchell
property, a larger cooling water lagoon to the east, and a smaller lagoon to the west. The
smaller, westernmost lagoon was backfilled sometime between 1964 and 1972. The larger
cooling water lagoon was. backfilled with sand in 1983. In 1987-88, a source removal action
was undertaken by one of the PRPs in this area under an order from the MDNR.
Samples from shallow surface soils were collected during both phases of the field
investigation. These include borehole samples and test pit samples collected during the Drain
Tile Study, which examined the .possible influence of several drain lines on soil
contamination in the lagoon area. The highest levels of contaminants were associated with
the soils around the drain Tiles with trichloroethene as high as 1,100,000 ppb, trans 1,2-
dichloroethene as high as 350,000 ppb. For more information on the soil contamination at
the Mitchell area refer to Table 1 in this ROD and the Drain Tile Study which is Appendix 1
of the RI report.
The most highly contaminated groundwater under the Mitchell property was found at a depth
of approximately 60 feet beneath the old lagoon area with trichloroethene as high as 4,600
ppb. Wells located just upgradient of the lagoon area at the same depth showed only low
levels of contaminants. The 60 foot depth at this location coincides with the top of the lower
aquifer on the western portion of the Clare Water Supply Site.
6
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EX-CELL-O AREA: Twenty-two soil samples from above the till unit were collected on
the Ex-Cell-O property, and seven samples were collected north and west of the Ex-Cell-O
property. The highest levels of contaminants were located in shallow surface soils at borings
taken just adjacent to the Ex-Cell-O building and under it with levels of trichloroethene in
soil as high as 37,000 ppb and Xylenes as high as 31,000 ppb at a depth of 3 feet.
All wells in the vicinity of the Ex-Cell-O building were completed within or above the till
unit. This discussion of ground water quality concerns only the perched water present above
the clay. The highest levels of contaminants were found at 4-7 feet below the surface just
south of the Ex-Cell-O building with trichloroethene as high as 20,000 ppb.
STANLEY On. AREA: Soil samples were collected from borings during both phases of
this investigation. A total of four such samples were collected from shallow soils in the
Stanley Oil area. The highest level of chemicals found in these soil samples were
Naphthalene at 7,000 ppb, xylenes at 3,600 ppb, toluene at 12 ppb, and methylene chloride
at 18 ppb.
A total of four monitoring wells were installed in the immediate vicinity of the Stanley Oil
area. The highest level of contaminants were found at 3-6 feet below the surface
immediately adjacent to the aboveground storage tanks with benzene at 1,600 #Lg/I,
ethylbenzene at 170 #Lg/I, xylenes at 1,000 #Lg/l, toluene at 42 #Lg/l, and methylene chloride
at 7 #Lg/l.
MDOT AREA: Ground water samples were collected in the Ann Arbor Railroad depot area
from three monitoring wells installed during the RI. The foUowing compounds were detected
in these monitoring wells: ethylbenzene at 460 #Lg/l, toluene at 310 #Lg/l; xylenes at 4,400
#Lg/l; trichloroethene at 7 #Lg/l; and methylene chloride at 4 #Lg/l.
Soil samples collected and analyzed by the MDNR in 1982 and 1983 in the MDOT area
found soils to contain: ethylbenzene at 9,000 ppb, xylene at 90,000 ppb, toluene at 5,000
ppb, carbon tetrachloride at.4l0 ppb, and perchloroethane at 260 ppb.
WEL TRONICS AREA: Fifteen soil samples were collected in the vicinity of the
Weltronics building. The soils were found to contain up to: 130 ppb of trichloroethene, 57
ppb of toluene, 12 ppb of methylene chloride, and 110,000 ppb of bis(2-ethylhexyl)phthalate.
One of the soil samples taken from a waste pile near the Weltronics building during the RI
revealed the presence of material which is classified by the Resource Conservation Recovery
Act (RCRA) program as hazardous by "characteristic". The material is classified as
"characteristic" because it has been tested using an Extraction Procedure (EP) to determine if
toxic levels of compounds can leach out of the material into groundwater. In other words, it
has been found to be EP toxic, which makes it a RCRA-regulated waste because it has a
hazardous characteristic. . The waste pile material was shown to have contained EP-toxic
7
-------
cadmium at 1.3 mg/kg and EP toxic lead at 25.90 mg/kg. The EP test has now been
replaced with a more aggressive leaching test called the Toxic Characteristic Leaching
Procedure (TCLP). Consequently, materials which were formerly tested using the EP test
are likely to test "TCLP-toxic" since the TCLP involves a more aggressive leaching
procedure. Additionally, references made to the EP characteristic may be replaced by
references to TCLP characteristic. For example, the material which was found to be EP
toxic at the Clare Site (discussed above in this paragraph) will have to be tested by the TCLP
to see if it is TCLP toxic prior to land disposal: If it is TCLP-toxic, it will have to be
treated to remove that characteristic prior to land disposal.
Thirteen ground water monitoring wells, three piezometers, and MW #5 are located in the
vicinity of the Weltronics building. In 1988, some of the wells installed in this area showed
that contaminant concentrations decreased with depth. For example, well WS-5 contained
1,I-dichloroethane, trans-l,2-dichloroethene, trichloroethene and vinyl chloride totaling 308
Ilg/l in 1988. Well WD-5 installed at approximately the same location but with a screen
depth 25 feet below that of WS-5 contained no chlorinated hydrocarbons above detection
limits. In 1989, WS-5 concentrations had all dropped below detection limits, while well 211,
which was screened approximately 10 feet deeper than WS-5 at approximately the same
location contained 1, I-dichloroethane, vinyl chloride, 1,2-dichloroethene and 1,1,2-
trichloroethane totaling 222 Ilg/l. .
AMERICAN DRY CLEANERS AREA: The MDNR collected a composite sample of the
upper 12 inches of the soil profile from immediately behind the American Dry Cleaners back
door in 1982 which contained xylene at 18,000 ppb, tetrachloroethene at 200 ppb, and
carbon tetrachloride at 40 ppb. . A groundwater sample was collected during the RI from the
monitoring well installed on the property by the MDNR in 1982. The analytical results of
this water sample revealed: 9 ppb of trans 1,2-dichloroethene, 84 ppb of tetrachloroethene,
and 2 and 1 parts per billion of trichloroethene and methylene chloride, respectively.
STANDARD On. AREA: Unsaturated zone soil samples were collected from 4 borings in
the Standard Oil Area. These revealed the presence of ethylbenzene at 26,000 ppb and
xylenes up to 120,000 ppb in the unsaturated zone. Soil samples were also collected from
two monitoring wells in this area. One sample from 47 feet depth contained trichloroethene
- and perchloroethene, the sum of which was 166 ppb. A deeper soil sample from a 75 foot
depth contained no compounds of concern above detection limits.
Groundwater samples were collected from 4 monitoring wells in this area. Analysis results
for these wells show trichloroethene up to 220 Ilg/l, trans-l,2-dichloroethene up to 85 }'g/l,
and vinyl chloride and perchloroethene were detected at concentrations below 5 Ilg/l.
8
-------
'.-ClLL-O .ORT" .RIA
@
.101
I"'CILL~ UI.
.1'1
+
.,:
..
i .. ,~r"ICO DItI CLIOIIII .ltiA
Do~ OOD ID
DoBiJI
Q"~8
00 D
c
t:
I
III
K
CCJ.
n [JD
00
ti
z
U
III
III
o
IIIITCMlLL .ltl.
.IW II
F "TN IT.
."O~
- US 10 0".1".01 DITCH
.ITCMILL IAIT UIA
."
..0
00
~,o
(;)0
-C
~~
~
WlLT"O.IICI ."IA
FIGURE 2
-------
SOURCE AREA -
,
MEDIA -
Acetone
2-butanone
Bc;nzene
*Toluene
Total Xylenes
Chloroethane
I,I-~ichloroethanc
trans 1,2-dichlorocthcne
Methylene Chloride
Trichloroethene
Tetrachloroethene
1,1 ,I-trichloroethane
1,2-dichloroethane
Napthalcne
1,I,2-trichloroclhane
Elhylbenzene
bis( ethylhexyl)phlhalate
Tolal TICs
Vinyl Chloride
Phenanthrene
Styrene
*Carhon Disulfide
TABtE 1
CLARE WATER SUPPLY SITE
MAXIMUM CONTAMINANT CONCENTRATIONS IN EACH SOURCE AREA
, <'
MITCIfELL AREA
Vadose
Zone
(pg/Kg)
5,000
2,000
5,000
3,000
350,000
6,000
1,100,000
40,000
510,000
69,600
" Ground
Water
(Pg/L)
30
20
340
1,100
1,400
4,600
NA
1,400
19
--
56
--
--
--
ND
--
13
"'Also present 111 lah hlanks, thought 10 he lah conlal11l11aols
53
EX-CELL-O AREA
SOil
?
(lijlkg)
270
--
57
-
-
--
-
-
-
--
--
--
--
-
--
--
NO
30
Ni>
12
18
ND
ND
NO
ND
ND
--
--
48
,"'" ."
. . . n.' ..
Gm~d
\Vater
OIVL) .'
37
--
-
--
-
-
--
--
ND
6
6
... ..... . "'
..... - .... .".
. """" -
........... n.,
'/""'D' g"y"""'"
;£.~..
~
P'.. . .. . .
. . . d" .. P'
.... . .....". .
'.,~~M(j"
otplUEA"
..',",'.."..."".,".',",,',",
. . ....... ... ..
()@~>
?W~r.'
..,..tPW}
~U("
{(#j/Kg) "
. .... ...
. n.,.. .
'.,..d~~94",.'
»'a't#t" ,.'
(M~iL)
-
S 7,000 13
-- 10 --
-- -- --
ND 12 2
NO 120,000 2
- - --
-- - 1
9 - 88
I 41 3
2 46 220
84 120 --
- -- -
- -- --
-- 1,200 -
-- -- --
-- 26,000 --
- -- --
6 118,900 17
ND -- 3
-- 900 --
-- 12 --
-- 160 --
-
I
2
-
34
120
4
150
-
I
--
-
71
2
-
--
--
--
-------
~
SUMMARY OF SITE RISKS
~
During the RI/FS, U.S. EPA and MDNR calculated the risks that the site would pose to
human health and the environment if no remedial actions were taken. This process is called
a baseline Risk Assessment (RA). The RA involves assessing the toxicity, or degree of
hazard, posed by substances related to the site, and describing the routes by which these
substances could come into contact with humans and the environment. Separate calculations
are made for those substances that can cause cancer (carcinogenic) and for those that can
cause non-carcinogenic health effects. The risks to human health are quantified by using
Cancer Potency Factors for carcinogenic contaminants and Reference Doses for
noncarcinogenic contaminants.
Cancer potency factors (CPFs) have been developed by EPA's Carcinogenic Assessment
Group for estimating excess lifetime cancer risks associated with exposure to potentially
carcinogenic chemicals. CPFs, which are expressed in units of (mg/kg-day)-l, are multiplied
by the estimated intake of a potential carcinogen, in mg/kg-day, to provide an upper-bound
estimate of the excess lifetime cancer risk associated with exposure at that intake level. The
term "upper bound" reflects the conservative estimate of the risks calculated from the CPF. .
Use of this approach makes underestimation of the actual cancer risk highly unlikely.
Cancer potency factors are derived from the results of human epidemiological studies or
chronic animal bioassays to which animal-to-human extrapolation and uncertainty factors
have been applied.
Reference doses (RIDs) have been developed by EP A for indicating the potential for adverse
health effects from exposure to chemicals exhibiting noncarcinogenic effects. RIDs, which
are expressed in units of mg/kg-day, are estimates of lifetime daily exposure levels for
humans, including sensitive individuals. Estimated intakes of chemicals from environmental
media (e.g., the amount of a chemical ingested from contaminated drinking water) can be
compared to the RID. RIDs are derived from human epidemiological studies or animal
studies to which uncertainty factors have been applied (e.g., to account for the use of animal
data to predict effects upon humans). These uncertainty factors help ensure that the RIDs
will not underestimate the potential for adverse noncarcinogenic effects to occur.
The National Oil and Hazardous Substances Contingency Plan (NCP) established acceptable
levels of risk for Superfund sites ranging from 1 in 10,000 to 1 in 1 million excess cancer
cases. This translates to a risk range of between lxl()'4 and lxl~. The NCP requires that
the RA consider exposure scenarios both for current land use and for a conservative
reasonable future use.
MEDIA AND CONTAMINANTS OF CONCERN
The media and contaminants of concern at the Clare site are listed in Table 2.
11
-------
l'AnLE 2 .
1988-1991 CONTAMINANT CONCENTRATION RANGES
CLARE WATER SUPPLY RIfFS
CI.-ARE, MICIDGAN
_1tJ..llL,
Uenzene 15-27 NO 1-1,800
1,I-dichloroellume 16-1,100 NO 1-300
Trans-I,2- . 5-1.800 13,000-350,000 3-5,000
dichloroethene
Cis-I,2-dichloroethene NO NO 1-37
Ethylhenzene 70-26,000 NO 1-460
.'
Methylene Chloride 5-1,000 140-1,200 1-1,400
Tef rachloroef hene 7-120 1,500-40,000 3-84
1, 1,2-frichloroethane 7-56 NO 1-71
Trichloroethene 6-150,000 2,700-1,100,000 1-20,000
Toluene 6-79 NO 1-310
Vinyl Chloride NO NO 2-32
Xylenes(Total) 5-120.000 NO 1-4,400
1,2-dichlornelh:me 6-19 NO NO
1.1,1-lrkhlurcH'lh:tne Q-21.000 HiO-51O.000 I-I.~OO
------------. --_._-~
Styrene 5-15 NO NO
N I) . - Nc.' I k.leclcl
2-4 NO NO
1-1.5 3 14- 3,000
1-35 6-18 30-120,000
1-36.9 NO NO
NO NO NO
2-3 1 7-6,000
NO NO 67-6,900
NO NO NO
4-21 5 430-24,000
NO NO 8-2,000
1-2 2 ND
NO ND 10-2,000
NO ND NO
ND 5 ND
ND ND ND
-------
EXPOSURE SCENARIOS
Persons who utilize municipal well water from the Clare Water Supply wellfield are
identified as the population at risk in the excerpts from the Baseline Risk Assessment (Table
3) prepared by the PRPs. This particular Risk Assessment was completed prior to the
current policy which requires all Risk Assessments to be performed by U.S. EPA. The
primary routes of exposure to contaminants in groundwater are ingestion, inhalation of
volatiles and dermal absorption. Benzene, Tetrachloroethene, Trichloroethene, methylene
chloride, 1,1 ,2-trichloroethane, and vinyl chloride are probable or actual human carcinogens
that are present in the groundwater contamination plume.
The carcinogenic and noncarcinogenic risks listed in Table 3 below were calculated by the
PRPs using the average concentration of contaminants for each of the 6 exposure scenarios
examined at the Clare Site:
TABLE 3
CARCINOGENIC AND NONCARCINOGENIC RISK CHARACTERIZATION
--
ADULT: 1 X 10-4 ADULT: 0.1
CHILD: 5 X l()"' CHILD: 0.04
"""'''v''''
)!$: ir: Ingestion of VOCs through the municipal
}@;m:} water supply for all residents of Clare;
::::r::,:::::~::::::::
:i:;I~: Dermal absorption of VOCs from showering
:mtt: to all residents of Clare;
111i1111111! ~:= ~::r:=n~~~~~::::~~~ren
,:':::I!:::!, Inhalation from showering to all residents of
;:;!t/\ Clare;
Dermal absorption and incidental ingestion
of VOCs from contaminated soils for
workers or children in contaminated soil
.::::::~:::::::::;::
:X*,::I Inhalation of volatile organic compounds
:!:fi{1::::~::: (VOCs) to residents who live or work near
::!:m:;!i~~::! water treatment plant.
ADULT: 8 X 10-7
CHILD: 2 X 1~
CmLD: 3 X 1007
ADULT 0.001
CHILD 0.001
0.00004
ADULT: 1 X 10-4
CHILD: 8 X 10-5
ADULT 0.2
CmLD 0.4
0.003
5 X 10-6
ADULT: 1 X 10-7
CHILD: 4 X 10-7
ADULT 0.0005
CHILD 0.002
The carcinogenic and non-carcinogenic risks above were calculated as if there were to be no
action taken at the Clare Water Supply Site. Since the estimated non-carcinogenic risk is less
than 1, no adverse non-carcinogenic effects would be expected. If the calculated non-
carcinogenic risk were greater than 1, adverse non-carcinogenic health risks would be
possible.
13
-------
The carcinogenic risks calculated for scenarios 1, 2, 4 and 5 individually are within the U.S.
EPA's acceptable risk range of Ix104 and 1x1()"6. When the risks from these pathways are
added to produce a sitewide risk the result is 2.Ix 104 which is just above the U. S. EP A's
acceptable risk range. The operation of the air stripping towers since March 4, 1991, has
temporarily reduced exposure of the public to unacceptable risk via scenarios 1, 2, and 4
since approximately 97% of the contaminants are being removed from the water supply prior
to distribution. Consequently, the only current risks are from scenarios 3, 5, and 6 which
estimate the risk from the contaminated soils, surface water, and the water treatment plant
aeration system emissions and these risks fall within the acceptable risk range.
SOURCES OF UNCERTAINTY IN RISK ASSESSMENT
While the level ofincreased risk calculated for these scenarios in total is only slightly over
the U.S. EPA's acceptable risk range, there are several factors explained below which were
not considered in the PRPs' risk assessment that impact the risks calculated by the PRPs:
1) The PRPs used the average concentration of contaminants in groundwater to calculate the
risks. The new Risk Assessment Guidelines state that in order to calculate the Reasonable
Maximum Exposure (RME), the upper bound of the 95% confidence interval on the data is
to be used rather than the average value. . This raises the level of risk under each of the
exposure scenarios. For example, the risk calculated by the PRPs for an adult drinking
municipal water was listed as 1 x 104. Using the upper bound of the 95% confidence
interval and calculating the RME for the same scenario results in a risk of 7.9 x 104.
2) Movement of the plume of groundwater contamination is continuing towards tlie municipal
supply wells. The PRPs' risk assessment evaluated exposures based upon the concentrations
of contaminants in the municipal water supply that were present during the Remedial
Investigation. The concentrations of VOCs such as Trichloroethene were on the order of 20
parts per billion (Ppb) in the municipal water supply wells. The concentrations of TCE in
the groundwater in the source areas are as high as 20,000 ppb, a thousand times greater than
the water currently being pumped by the municipal wells.
As stated above, the air stripper is currently removing approximately 97% of the VOCs from
the water supply. The levels of TCE in groundwater currently being pumped by the
municipal wells is around 20 ppb. Removal of 97% of 20 ppb leaves 0.6 ppb which is
below the Maximum Contaminant Level (MCL) and also below the detection limit of the
laboratory. As the more highly contaminated portion of the plume moves toward the supply
wells, the level of TCE entering the supply wells will increase. It is difficult to say exactly
how much it will increase, but if the groundwater from the source areas were to be diluted
100 times by the time it reached the supply wells, it would still contain approximately 200
ppb of TCE. Removal of 97 % of the TCE by the air strippers would then leave 6 ppb in the
water which would exceed the MCL. Consequently, as the more contaminated portion of the
plume reaches the supply wells, the current air stripping treatment may not maintain the
quality of the drinking water supply.. .
14
-------
3) As the more highly contaminated groundwater in the plume reaches the municipal supply
wells, the level of VOCs emitted to the atmosphere will increase. The air stripper installed
during the 1st operable unit is currently removing approximately 97% of these contaminants
from the drinking water and transferring them to the atmosphere. While the levels emitted to
the atmosphere do not currently pose an unacceptable health risk, they will increase through
time as the more highly contaminated portions of the plume move towards the supply wells.
4) Natural degradation of TCE continues to produce higher levels of the more toxic daughter
product vinyl chloride in the groundwater and also in the air emissions from the air stripper.
5) Although the level of risk from dermal contact with and incidental ingestion of
contaminated soils falls within the acceptable risk range of 104 to 1
-------
if it is replaceable. For Class I and IIA aquifers, EP A's preference is for rapid restoration
(within 1 to 5 years). The minimum restoration timeframe however, is determined by the
hydrogeological conditions, the specific contaminants at the site, and the size of the
contaminant plume.
For Class I and II ground waters , the preliminary remediation goals are generally set at
Maximum Contaminant Levels (MCLs), and non-zero Maximum Contaminant Level Goals
(MCLGs) where relevant and appropriate, promulgated under the Safe Drinking Water Act
or more stringent state standards. Pursuant to the SDW A, contaminant-specific levels or
MCLs have been promulgated and are periodically revised which represent the maximum
permissible level of a contaminant in water which is delivered to any user of a public water
system. The MCLs for the contaminants of concern at the Clare Site are shown in Table 4.
The State of Michigan has also set cleanup levels for groundwater under Act 307. The
substantive provisions of Parts 6 and 7 of the Michigan Act 307 Rules are considered
ARARs for the remedial action to be undertaken at the Clare Water Supply Site. These
Rules provide, ~ ilia, that remedial actions shall be protective of public health, safety,
and welfare and the environment and natural resources. The Act 307 Type B cleanup levels
for groundwater and soil are also shown in Table 4.
The U.S. EPA has determined that the cleanup levels in Table 4 derived under Michigan's
Act 307 for groundwater and soils will also be protective of human health and the
environment by reducing the current and potential future risk to within or below the U.S.
EPA's acceptable risk range. The Type B cleanup levels for the 7 carcinogens listed in
Table 4 (denoted with a ** by the name of the compound) correspond to a 1 x 1()"6 level of
risk for each individual chemical. Setting the cleanup levels to the Type B Cleanup Level
for each individual compound, achieves an aggregate risk level for carcinogens of 7 x 1()"6.
For comparison, the concentration in water which equals a 1 x 10"' level of risk is also
shown in Table 4 for the 6 carcinogens at the Clare Site. Also, the Oral Reference Dose, or
estimate of a daily exposure to the human population that is likely to be without appreciable
risk of deleterious non-carcinogenic effects over a lifetime is also shown in Table 4 for
comparison. .
16
-------
CLEANUP ACTION LEVEL (in ppb)
Benzene** 1 20 5 100
Vinyl Chloride** *0.02 *0.4 2 1.5
Trichloroethene** 3 60 5 300
Tetrachloroethene** *0.7 14 5 70
Methylene Chloride** 5 100 5 500
Trans 1,2-Dichloroethene 100 2,000 100
'Cis 1,2-Dichloroethene 70 1,400 70
Total Xylenes 300 6,000 10000
Toluene 800 20,000 1000
Ethylbenzene 70 1,000 700
l,l-Dichloroedtane 700 14,000
1,2- Dichloroethane** *0.4 *8 5 40
1,1,2- Trichloroethane** *0.6 12 5 60
1 , 1 , I-Trichloroethane 200 4,000 200
Styrene 1 20 100
* e e e etectlon lImt or 0 ese contanunants 1S Jl. 1D
water, and 10 Jl.glKg in soil. The cleanup levels with an asterisk in the table are lower than
the currently acceptable MDL so the cleanup level that will be enforced for this action will
be the MDL for the asterisked contaminants.
** Classified as actual or possible human carcinogen'
The areas of soil contamination which exceed cleanup levels for soil are depicted in Figures
4, 5, and 6. The general area encompassed by groundwater which exceeds the cleanup
levels for groundwater is shown in Figure 7.
17
-------
Cleanup Levels Where Groundwater Discharges to Surface Water
The potential exists for groundwater to naturally discharge into the US 10 Drainage Ditch.
In the Proposed Plan, discharge limitations were proposed for the four compounds listed in
Table 5 below. These discharge limitations were calculated in accordance with Rule
323.1057 of the Water Resources Commission Act (1929 PA 245, as amended). These
limitations are more stringent than the Michigan Act 307 Type B cleanup criteria given in
table 4. These limitations are to be applied at the point where groundwater naturally
discharges to surface water. Michigan Administrative Code (MAC) Rule 299.5713 requires
that these values not be exceeded at a point where groundwater naturally discharges to
surface water. Demonstration of compliance with this rule may be made by monitoring at
the groundwater-surface water interface, or by predictive modeling.
It is not necessary that the Table 5 values be achieved throughout the aquifer; however, a
remedial action plan which proposes to meet the Table 5 values throughout the aquifer in lieu
of monitoring at the interface is an acceptable substitute.
TABLE 5
RULE 57 DISCHARGE LIMITATIONS THAT ARE MORE STRINGENT
mAN ACT 307 TYPE B CLEANUP LEVELS
1111111111111;1'111'1111111111111'11111111111111 -
Total Xylenes 60
Toluene 100
Ethylbenzene 30
1 , 1 , 1 -trichloroethane I 00
The analytical data in the RI revealed that there were 8 occurrences at the Clare Site where
the groundwater exceeds the Table 5 value. These are listed in Table 6 below:
TABLE 6 OCCURRENCES OF CONTAMINANT LEVELS IN
EXCESS OF RULE 57 SURFACE WATER CRITERIA
~::::Bi.U: lit.li'!illill"ill;' liillllllliilll!illliillilliililillillillllllllllillill1IIIIIil 1111~i,IIII.I'lif
!:~11t~~~JI~f~i~1~!j;1
B40 60' I , I , I-trichloroethane 1 ,400
SW-5 3-6' Ethylbenzene 1 10
SW-5 3-6' Total Xylenes 1 ,200
SW- 13 3 .33-6. 33 ' Ethylbenzene 170
SW- 13 3.33-6. 33 ' Total Xylenes 1 ,000
WS- 12 22-27' Ethylbenzene 460
WS- 12 22-27' Toluene 3 10
WS- 12 22-27' Total Xylenes 4,400
18
-------
These 8 occurrences represent 4 separate locations. These 4 locations are shown on Figure
3. Superimposed on this figure is the average groundwater flow direction at each of the 4
locations. Figure 3 shows one location where groundwater contaminated at levels over the
Table 5 values may impact surface water -- near' the southeast comer of the Mitchell Building
where the old lagoon area used to be located -- which is also the location where the highest
levels of surface water contamination were detected in 1985.
Consequently, monitoring of the groundwater-surface water interface will be conducted
during the remedial action at the locations where ground water discharges into surface water
to demonstrate that this requirement is achieved. If this requirement is not being achieved,
U.S. EPA, in consultation with MDNR, will evaluate the available information and develop
an appropriate response action. '
Ann Arbor',
Railroad Depot (forme;)'
1'1~~
'N
I
1i~~
~
.:~,,~
:~, ~'."~
. I '- .:,:;z.;
i HOlleYIES~ /
, Fostoria Screw
L I Holley
,.' :::':':... .." I .". . .flli~treet
U.S: 10 Drainage Ditch
I
Not 10 Scale
~~~~I well0
CI 5th Street (U.S. 10)
are l I
Public . --
Works American
:' II --1 " /J, ~ ~ry-Cle.1ning
. I , ~ .ndard 011 (form",)
'-0~ Iwater Tre,~I~;:ent Plant'."
. Municipal Wn/I
(~I
, ...
;"":. ..........,
LEGEND
D Arrow Indicates Groundwater
Flow Direction at that pomt
,
,
Gi
~
III
Q
o ~
Municipal Well
.... ..
Little Tobacco Joint Drain
J
GROUNDWATER CONTAMINATION OVER RULE 57 SURFACE WATER
FIGURE 3 CRITERIA
19
-------
Seven (7) remedial action alternatives were carried through a detailed analysis in the
Feasibility Study prepared for the Clare Water Supply Site by the PRPs. Alternative #1 is
the no action alternative, which is required by the NCP. Alternative #2 utilized only
institutional controls such as deed, use and access restrictions to control access to
contaminated ground water and soils. Alternative #3 is the same as Alternative #2 except
that contaminated soils are capped. Alternative #4A provides for in-situ vacuum extraction
of organic contaminants from the soils. Alternative #4B provides for excavation and off-site
incineration of contaminated soils. Alternatives #SA and #SB both address contaminated
ground water only, but use air stripping/carbon adsorption or UV Photo-Chemical oxidation,
respectively, to treat contaminated ground water which is collected from extraction wells,
treated, and.then either reinjected into the aquifer, discharged to surface water or to the
Publicly Owned Treatment Works (POTW).
Detailed descriptions of each of these 7 remedial alternatives can be obtained in the FS. A
brief description of the 7 alternatives follows on the next several pages. A summary of the
components and costs associated with all 7 alternatives is presented here in Table 7.
MEDIA-SPECmc NATURE OF mE REMEDIAL ALTERNATIVES
Alternatives #4A and #4B are intended to address the soil media only. Alternatives #SA and
#SB are intended to address the groundwater media only. The evaluation of the soil
alternatives discusses how well each of these alternatives addresses soil contamination and the
evaluation of the ground water alternatives discusses how well each of these alternatives
address ground water contamination. This approach of evaluating media-specific alternatives
individually requires that a combination of alternatives be selected to successfully meet the
nine criteria. The combination of either Alternative #4A or #4B with one of the groundwater
alternatives (#SA or #SB) could be protective of both soil and groundwater and meet ARARs
for both media. .
The U.S. EPA has decided to select a combination of alternatives using one of the
alternatives that are designed to address soils (#4A) and one of the alternatives designed to
address ground water (#SB) in concert with each other.
Since these 2 alternatives were developed as individual alternatives, they include components
which are common to each other. The detailed components of the combination of
Alternatives #4A and #5B are listed in the estimate of capital costs given in Table 8 of this
Record of Decision. The FS only contains the detailed cost estimates for each individual
alternative. The detailed cost estimate breakdown for the annual operation and maintenance
of the combination of alternatives is given in Table 9 and the summation of annual O&M
costs and calculation of Total Present Worth of the combination of alternatives is given in
Table 10.
20
-------
TABLE 7
REMEDIAL ACTION ALTERNATIVE COMPONENTS AND COSTS
CLARE WATER SUPPLY
CLARE, l\1ICmGAN
IIII!III~I~IIIII~II/!I: 1/111111/1!11~'d~iillllll:~il 11/1111111111/1111/1111,:II:I!
ALTERNATIVE DESCRIPl'ION
Alternative #1
No Action
o No Action
o Monitor Groundwater
$
246,000
172,000
$ 2,886,000
Alternative #2
Institutional Action 0 Use, Deed, Access Restrictions $ 449,000 204,000 $ 3,562,000
o Drainage Ditch Diversion
0 Monitor Ground Water
Alternative #3
Institutional Action 0 Use, Deed, Access Restrictions $ 1,356,000 197,000 $ 4,291,000
with Containment 0 Drainage Ditch Diversion
0 Cap contaminated soil areas
0 Monitor Ground Water
Alternative #4A
In-Situ Soil Vapor 0 Use, Deed, Access Restrictions $ 8,386,000 590,000 $ 20,467,000
Extraction (SVE) 0 Drainage Ditch Diversion
0 SVE with Carbon Adsorption
0 Shallow aquifer dewatering
0 Monitor Ground Water
Alternative #4B
SoiUSediment 0 Use, Deed, Access Restrictions $ 82,720,000 198,000 $ 85,760,000
Excavation, Orr-Site 0 Drainage Ditch Diversion
Treatment, Orr-Site 0 Excavate Contaminated Soil
Disposal 0 Off-Site Treatment (Land Ban)
0 Disposal in Off-Site Landfills
Alternative #5A
Ground Water 0 Ground Water Extraction $ 2,054,000 1,405,000 $ 23,616,000
Extraction, 0 Air Stripping/Carbon
Treatment by Air 0 Liquid Carbon Adsorption
Stripping! Carbon 0 Shallow Well Reinjection
Adsorption and 0 Monitor Ground Water
Shallow Well
Reinjection
Alternative #5B
Ground Water 0 Ground Water Collection $ 2,272,000 594,000 $ 11,374,000
Extraction, 0 Extraction Wells
Treatment by UV 0 UV Photochemical Oxidation
Photochemical 0 Catalytic Ozone Decomposition
Oxidation and 0 Shallow Well Reinjection
Shallow Well 0 Monitor Ground Water
Reinjection
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The No Action alternative is a baseline for comparison against all other alternatives. No
remedial action would be taken at the site with regard to soil, sediment, groundwater or
surface water contamination. No restrictions would be placed on access or future use of
the site. Treatment of the city water supply would continue to be provided at the well
heads before distribution to city residents as part of the Interim Remedial Action, a
separate operable unit. Contaminant migration would be traced through a ground water
and surface water monitoring program. Representative monitoring wells, consisting of
both existing and new wells, would be used. The wells would be sampled once per
quarter and water levels would be recorded.
Capital Cost: $ 246,000
Average Annual O&M Cost: 172,000
Total Present Worth: $ 2,886,000
,.,.,__-
This alternative would include the implementation of institutional actions (deed, use, and
access restrictions), ditch rerouting, and a monitoring program.
Deed restrictions would be placed on the properties where cleanup action levels are
exceeded. These would limit further construction, excavation, and or well installation
activities. Ground water use restrictions would be placed on the areas where ground
water cleanup action levels are or would be exceeded. Treatment of the city water supply
would continue to be provided at the well heads before distribution to city residents as
part of the Interim Remedial Action, a separate operable unit.
In order to minimize transport of contaminated sediment off-site, the US 10 Drainage
Ditch would be rerouted around the areas where soil/sediment cleanup objectives are
exceeded. This would preferably be done during a time of low surface water flow to
minimize the amount of water needing handling during construction.
The contaminated ditch area would be backfIlled to grade with dean soil and inspected
periodically. The areas containing contaminated soil and sediment above the cleanup
objectives would be fenced. A 6-foot chain-link security fence topped with 3-strand
barbed wire would be placed around each area. The fenced areas would be clearly posted
with signs every 50 feet. The fencing and signs would be inspected periodically and
maintained in good repair. Access to the fenced areas by workers would not be allowed
unless adequate protective clothing/equipment were provided.
DURATION: 6 Months
Capital Cost: $ 449,000
Annual O&M Cost: 204,000
Total Present Worth: $ 3,562,000
22
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_.'.~fi_-
This alternative would include the implementation of institutional actions (deed, use, and
access restrictions), ditch rerouting, construction of a multi-media cap, and a monitoring
program.
This alternative is essentially the same as alternative #2, except that it provides for a
multi-media cap to be constructed over each area where soil/sediment cleanup objectives
are exceeded. The caps would function as moisture barriers to inhibit the infiltration of
precipitation and would consist of a low-permeability barrier layer to prevent the vertical
migration of water, a lateral drainage layer to direct water off of the low-permeability
barrier, and a vegetative cover to limit erosion and provide frost protection.
The low-permeability layer of the cap would be designed as a composite layer consisting
of two feet of soil and a synthetic membrane liner. The synthetic membrane would
function as the primary inf1ltration barrier. The soil liner is included as a backup
measure to increase liner integrity and must have a permeability of no more than I x 1007
em/sec. The surface of the low permeability layer would be sloped at approximately
three percent to direct drainage toward the edge of the cover.
The drainage layer would be placed directly over the low-permeability barrier and consist
of a one-foot thick sand/gravel layer. The drainage medium would be selected to provide
a transmissivity of at least 5 x lQ4 m2/sec. The drainage layer would be covered with a
non-woven geotextile fabric m order to inhibit the migration of fine particles from the
vegetative cover soil, limiting the potential for clogging.
A two foot thick vegetative cover would be placed over the drainage layer to provide
erosion control and frost protection. The vegetative cover soils would be lightly
compacted to prevent rutting from vehicles used for cap maintenance. The cover surface
would be fertilized, seeded, and mulched to create a dense vegetative cover. The edge of
the cap would be sloped to blend it into existing terrain. A 6-foot security fence topped
with 3 strands of barbed-wire would be placed around each of the capped areas.
DURATION: 1 year
Capital Cost: $ 1,356,000
Annual O&M Cost: 197,000
Total Present Worth: $ 4,291,000
23
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This alternative would include the implementation of institutional actions (deed, use, and
access restrictions), ditch rerouting, construction of an in-situ soil vapor extraction
system, and a monitoring program. Soil and sediment with contaminant levels exceeding
cleanup objectives would be treated in-situ by soil vapor extraction to remove volatile
organic contaminants. A total of 54,800 cubic yards of soil, including that under
buildings would be treated.
Within the treatment areas, ranks and rows of vacuum extraction and air inlet wells
would be constructed to provide optimum control of air flow rates and pathways. The
initial spacing of the wells has been estimated based on existing site and soil conditions
for costing purposes. Final distances between wells would be determined through pilot
study field data. The wells would be constructed with a 4-inch diameter Schedule 40
PVC pipe, screened with a O.OIO-inch slot size. Sand pack would be installed around the
well screen section and extended to approximately two feet above the top of the screen.
The remainder of the well would be grouted to prevent leaks around the solid riser pipe.
If significant groundwater exists in the soil to be extracted, dewatering would be
required. This would be accomplished by installing dewatering wells around "the
perimeter of each area. The extracted water would be treated by carbon adsorption
before discharge.
The vapor extraction wells would be connected to the suction side of a blower. The
vacuum at each of the inlet wells would be monitored. Operation of the system may
include drawing fresh air from any of the inlet wells, balancing the vacuum at all inlet
wells, or allowing for free air admittance.
A mist eliminator would be installed to remove moisture in the soil gases, preventing
damage to the rotating lobes of the blower. The air would flow from the vapor
extraction wells to an in-line mist eliminator located in the suction line of the blower.
The entrained droplets would be removed in the mist eliminator and collected for proper
disposal. The blowers would be a positive displacement-lobe type. Suction and
discharge resonant-type sound suppressors would be provided to help reduce the normal
noise of the air blower. The discharge from the blower would be routed to two granular
activated carbon (GAC) filter units connected in series. The gas flow from the second
GAC unit would be discharged to the atmosphere through a vent stack. After completion
of the venting process or as the GAC units lose their effectiveness, the GAC units would
be returned to the carbon supplier for carbon regeneration and thermal destruction of the
collected VOCs.
DURATION:
Capital Cost:
Annual O&M Cost:
Total Present Worth:
10 years
$ 8,385,000
590,000
$ 20,467,000
24
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:!.::m~._.!::~!i!:.:.::..::~lmM_IIQ!I.::IJ.m.:~l!f$mlg!!&~~_ff.fgIE~I!:::::
In addition to deed and access restrictions, this alternative would provide for excavation
of all accessible soil and sediment with contaminant levels exceeding the cleanup
objectives. Due to the presence of a perched water table in discontinuous locations,
dewatering of the perched water by wells installed around the perimeter of each area may
be required before excavation. The extracted water would be treated by carbon
adsorption before discharge. A water storage tank would temporarily hold the water to
allow for the most efficient sizing of the carbon adsorption units. Unless excavation is
conducted during a time when there is no flow in the US 10 drainage ditch, temporary
rerouting of the flow in the ditch would be necessary during excavation. In order to
allow excavation of the soils close to building, sheet piling would need to be installed.
Approximately 15,600 cubic yards of soil and sediment with contaminant levels exceeding
cleanup objectives are located under buildings. In order to protect the structural integrity
of the buildings, this soil would remain In place.
Pretreatment of this excavated soil would be required if the contaminant concentrations In
the soil exceeded treatment standards of the RCRA Land Disposal Restrictions (LDRs).
The excavated soil would be loaded into lined trucks and transported as a hazardous
waste to a RCRA-permitted incineration facility for treatment in a rotary kiln incinerator.
After incineration, the treated waste would be transported to a landfill for disposal.
Extensive fingerprint sampling of the waste would be required to allow the Treatment,
Storage, or Disposal (fSD) facility to accept the excavated material. The excavated areas
would be restored to grade with uncontaminated fill; regraded, and seeded or paved, as
required.
DURATION: I year
Capital Cost: $ 82,720,000
Annual O&M Cost: 198,000
Total Present Worth: $ 85,760,000
-
This alternative would include the implementation of institutional actions (deed, use, and
access restrictions; ditch rerouting, construction of ground water collection wells, an air
stripping/carbon adsorption treatment system, and shallow reinjection wells; and a
mOl)itoring program. Contaminated ground water would be pumped from four (4)
extraction wells, volatile organic contaminants would be removed using an air stripping
column followed by GAC polishing, and the treated water would be reinjected into the
aquifer through four injection wells. The number, location and pumping rates of the
extraction wells may have to modified during the design phase.
DURATION: over 100 years
Capital Cost: $ 2,054,000
Annual O&M Cost: 1,405,000
Total Present Worth: $ 23,616,000
.,~
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This alternative would include the implementation of institutional actions (deed, use, and
access restrictions; ditch rerouting, construction of ground water collection wells, a
UV /Chemical Oxidation treatment system and shallow injection wells, and a monitoring
program. Contaminated ground water would be pumped from four (4) extraction wells,
volatile organic contaminants would be removed using UV /Chemical oxidation and the
treated water would be reinjected into the aquifer through four injection wells. The
number, location and pumping rates of the extraction wells may have to be modified
during the design phase.
DURATION: over 100 years
Capital Cost: $ 2,272,000
Annual O&M Cost: 594,000
Total Present Worth: $ 11,374,000
SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES .
In order to determine the most appropriate alternative for the Clare Water Supply site, the
alternatives were evaluated against each other. Comparisons were based on the nine
evaluation criteria outlined below.
1.
Overall Protection of Human Health and the Environment addresses
whether a remedy adequately protects human health and the environment and
whether risks are properly eliminated, reduced, or controlled through
treatment, engineering controls, or institutional controls.
2.
Compliance with Applicable or Relevant and Appropriate Requirements
addresses whether a remedy meets all state and federal laws and requirements
that apply to site conditions and cleanup options.
3.
Long-Term Effectiveness and Permanence refers to the ability of a remedy
to reliably protect human health and the environment over time once cleanup
goals have been met.
4.
Reduction of Toxicity, Mobility, or Volume through Treatment are three
principal measures of the overall performance of an alternative. The 1986
Superfund Amendments and Reauthorization Act (SARA) emphasizes that
whenever possible, the U.S. EPA should select a remedy that will permanently
reduce the level of toxicity of the contaminants at the site, the spread of
contaminants away from the site, and the volume, or amount, of contaminants
at the site.
26
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5.
Short-Term Effectiveness refers to the likelihood of any adverse impacts to
human health or the environment that may be posed during the construction
and 'implementation period until cleanup goals are achieved.
6.
Implementability is the technical and administrative feasibility of a remedy,
including the availability of materials and services needed to implement the
remedy.
7.
Cost includes capital, annual operation, and Total Present Worth costs of
implementing a remedy. .
8.
State Acceptance indicates whether, based on its review of the initial data
submissions by the PRPs and Proposed Plan, the State of Michigan (MDNR)
concurs with, opposes, or has no comment on the alternative the U. S. EP A is
selecting as the preferred response technology for the site.
9.
Community Acceptance indicates whether the public concurs with, opposes,
or has no comments on the remedy presented in the U.S. EPA's proposed
plan.
The section below profiles the performance of the remedial alternatives against the nine
criteria, noting how they compare to each other.
OVERALL PROTECTION OF HUMAN HEALTH AND THE ENVIRONMENT
With the exception of Alternative #1, and assuming all deed, use and access restrictions are
adequately enforced, all alternatives will be protective of public health an4 the environment.
Alternatives 2 and 3 would be the least reliable since all of the contaminant mass remains in
place and is not subject to any treatment. For Alternative #3, given the site conditions,
contaminants under the cap would be exposed in the future if deed, use or access restrictions
are not effective. Consequently, Alternatives 1, 2, and 3 would not significantly reduce risk
since the contaminants would continue to leach into groundwater.
While the soil alternatives (#4A or #4B) or the groundwater alternatives (#SA or #SB) would
not be as protective, the combination of either Alternatives #4A or #4B with one of the
groundwater alternatives #SA or #5B would be protective of both soil and groundwater and
meet ARARs. Alternatives #4A or #4B would address contaminated soils and eliminate
much of the threat posed to human health by continued leaching of contaminants from the
soil into groundwater. With the addition of an alternative to address the contaminated
groundwater, either #5A or #SB, the increased lifetime cancer risk can ultimately be brought
down to within or less than the U.S. EPA's acceptable risk range within a reasonable period
of time. Operation of the air stripping system must continue to work in concert with the
other remedial alternatives to prevent exposure to contaminants during the time it takes to
achieve remedial action objectives. .
27
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COMPLIANCE WITII ARARs
The Maximum Contaminant Levels (MCLs) required of public water supplies by the Safe
Drinking Water Act (SDW A) are being maintained currently through the use of the air
stripping treatment system prior to distribution. Since the air stripper leaves 3 to 10% of the
volatiles in the water after treatment, and monitoring data indicate that the plume is moving
towards the municipal wells, eventually, the air strippers will not be able to maintain the
MCLs whe~ more highly contaminated portions of the plume reach the municipal wells.
The most conservative chemical-specific ARARs for groundwater are the Michigan Act 307
Type B standards. These could be met by either Alternative #5A or #5B. The chemical-
specific ARARs for soil and sediment are also derived from the Act 307 standards and these
could be met by Alternatives #4A or #4B. For Alternative #1, #2 or #3 to meet the
chemical-specific ARARs for soils (the 307 standards) U.S. EPA, in consultation with
MDNR, would have to determine that the Clare Water Supply Site meets the requirements
for a Type C Cleanup. U.S. EPA has decided that the appropriate cleanup levels for
groundwater are the Type B criteria as explained on page 16 of this ROD. .
Some contaminants at this Site are RCRA listed wastes. Trichloroethylene (TCE) and
tetrachloroethylene (PCE) are RCRA listed wastes FOOl and Foo2. Because of this, the
removal of the soil under Alternative #4B (and Alternative #4A, if soil returned to the
surface from drilling or trenching operations were moved from the area of contamination)
would trigger RCRA requirements, including treatment and disposal requirements provided in
the Land Disposal Restrictions (LDRs). Under Alternative #4B, residues generated from
incineration of the soil would be disposed of in an off-site landfill. Unless delisting of the
waste is accomplished, the treated waste would have to be disposed of in a RCRA Subtitle C
landfill. If the contaminated soil is not removed, as in Alternatives #1, #2, #3, #4A, #5A
and #5B, the RCRA closure requirements are not applicable because the jurisdictional
prerequisites for their applicability are not met. Also, in both Alternatives #4A and #SA, the
carbon adsorption units will capture solvent constituents from the listed solvents, making the
spent carbon hazardous waste. In addition to the listed waste, the spent carbon may also
retain enough solvent to become characteristic. If the carbon is to be regenerated, it may be
treated only in a unit in compliance with RCRA regulations for miscellaneous units, as set
forth in 40 CFR Part 264 Supart X.
Emissions from the treatment system in Alternative #4A is required to meet the substantive
provisions of Michigan's Act 348. U.S. EPA will require monitoring of off-gas emissions to
ensure that Alternative #4A will achieve this requirement. It may be necessary to provide
for the use of vapor phase carbon adsorption prior to off-gas emission to the atmosphere in
order to meet these requirements. .
Aliernative #5B may generate ozone as its only byproduct. Clare County, Michigan, is an
attainment area for the ozone National Ambient Air Quality Standard of 0.12 ppm. . In
Region 5, this standard has been applied as an ARAR for remediation work. Alternative #5B
includes. a pilot study that will verify the efficiency of the catalytic ozone decomposition unit
in order to help ensure that the ozone standard will continue to be maintained.
28
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The combined remedy chosen will meet chemical-specific ARARs for both groundwater and
soils.
LONG- TERM EFFECTIVENESS AND PERMANENCE
Long-term residual risk is greatest for Alternatives 1, 2, and 3 since no treatment is being
performed. If institutional controls (deed, use and access restrictions) are enforced and an
adequate source of drinking water is available, the current residual risk should be negligible
for all alternatives except Alternative #1. However, through time, as more highly
contaminated groundwater moves toward the municipal wells, the levels of VOCs which are
left in the municipal water supply and also emitted to the atmosphere by the existing air
stripping towers may increase.
Alternatives #4A and #4B reduce residual risk from exposure to soil and sediment through
treatment. In addition, residential, commercial, and industrial developments can be
prevented by imposing deed restrictions. Access restrictions provided by fencing preveni
direct contact. The potential for skin irritation from direct contact with contaminated
sediment should be eliminated after completing the ditch rerouting and enforcement of access
restrictions.
Alternatives #5A and #5B reduce residual risk from exposure to groundwater through
treatment. In addition, ground water use restrictions and an adequate source of drinking
water minimize the residual risk from ground water.
The reliability of all alternatives except Alternative #1 depends on the enforcement of
institutional controls. Greater degrees of reliability are offered by the more treatment-
intensive alternatives, since institutional controls are relied upon to a lesser degree. If
institutional controls were to be weakened by future legal or regulatory changes or
disregarded by future property owners, and the site developed, the risk to human health
could be significant.
Consequently, the use of a combination of alternatives, #4A to address contaminated soils
and #5B to address contaminated groundwater, could ultimately eliminate the need for long
term enforcement of institutional controls and provide a sitewide remedy which is effective in
the long term.
REDUCTION IN TOXICITY, MOBILITY AND VOLUME TIlROUGH TREATMENT
The only alternatives which utilize treatment are Alternatives #4A and #4B for soils and #5A
and #5B for groundwater.
Alternative #4A would treat more soil than Alternative #4B since #4A is conducted in-situ
and it can be performed on soils which are located under buildings. Alternative #4B, which
involves excavation would not be able to treat the 15,000 cubic yards of contaminated soil
which is located under buildings.
29
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Alternative #SA provides for treatment of VOCs only after contaminated vapor carbon is
removed from the system and regenerated off-site. Alternative #5B provides treatment at the
site by emitting ozone as its only byproduct and then decomposing the ozone within the
catalytic ozone decomposition unit. Consequently, Alternative #5B would produce no
residues, sludges, or spent adsorbents. It essentially reduces the volume of contaminants to
nothing as part of its process, whereas Alternative #5A would rely upon off-site regeneration
to achieve volume reduction through treatment.
The combination of a soil and groundwater treatment alternative will work together in several
different ways to achieve a higher reduction in toxicity, mobility and volume than one of the
soil or groundwater alternatives by itself. For example, the Soil Vapor Extraction alternative
could allow increased air flow through the air inlet wells into the subsurface. This would
enhance any aerobic bacterial decomposition of VOCs that may be occurring. Additionally,
the extraction of groundwater may lower the water table in the source areas slightly which
would enhance the effectiveness of the soil vapor extraction system since it works better in
soils which are not saturated.
SHORT-TERM EFFECTIVENESS
Actions under all alternatives would be performed such that there would be minimal risk to
the community and to workers. This would mean that appropriate health and safety measures
would be observed during the construction and operation phases of the alternatives.
Dust control technologies and erosion/runoff controls will mitigate environmental impacts
caused by handling of the contaminated soil and sediment during Alternatives #4A, #4B, #5A
and #5B. Careful monitoring of ~e vapor extraction system during the operation phase of
Alternative #4A would mitigate impacts from possible emissions releases. Emission of
volatiles resulting from the treatment of the groundwater in Alternatives 5A and 5B will be
monitored and a contingency plan will be included with the design to mitigate impacts from
possible emissions releases.
Completion of Alternatives #2, #3, and #4B would take the least time (from 6 months to 1
year), but would not by themselves achieve all remedial action objectives since they only
address soils. Implementation of either of the groundwater alternatives, #5A or #5B, by
themselves would take in excess of 100 years to ac;hieve remedial action objectives since the
contaminants in the soils would continue to leach into groundwater. It should be noted that a
study entitled "Evaluation of Groundwater Extraction Remedies" found that continued
leaching from source areas was one of several factors that limit the effectiveness of
groundwater extraction systems. The remediation time frame should be significantly reduced
by implementation of a soil treatment alternative (#4A or #4B) in combination with a .
groundwater alternative (#SA or USB). The exact prediction of remediation time frame for
the combination of soil and groundwater alternatives is difficult, based upon the available
data, however, the U.S. EPA estimates the aquifer cleanup time with a combination
alternative at approximately 30 years.
30
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IMPLEMENTABILITY
The institutional controls employed by all alternatives except Alternative #1 may be difficult
to enforce. Limited difficulties should be associated with the rerouting of the ditch
(Alternatives #2, #3, #4A, #4B, #5A, and #5B) or the construction of a cap (Alternative #3).
The installation of the soil vapor extraction system in Alternative #4A.may be difficult inside
existing structures due to existing concrete floors and installed equipment. If significant
ground water exists in the soils to be vapor extracted, a dewatering system will be necessary
and the operation of the vapor extraction wells would depend on the effectiveness of the
dewatering system. All activities for all alternatives would need to be coordinated with
concurrent manufacturing activities.
Soil vapor extraction, ground water air stripping with carbon adsorption, and ground water
UV Photochemical oxidation are demonstrated technologies that have adequate equipment and
specialists available. More than one vendor would be available to provide competitive
bidding for each of these technologies. Adequate facilities exist for the regeneration of
carbon (Alternatives 4A, 4B, and 5A) although they are some distance from the site. The
availability of incinerators and landfills in the State of Michigan that can accept, treat, and
dispose of the excavated contaminated soil and sediments generated by Alternative #4B is
limited. It will likely be necessary to dispose of this waste out of state.
Due to long-term site monitoring activities, coordination among agencies, especially the
USEPA, MDNR, and MDPH, will be required. Consultation with these agencies would also
be involved to insure that the substantive environmental requirements are applied to and met
by this action.
COST
The estimated capital costs (See Table 7) range from $246,000 for Alternative #1 to
$82,720,000 for Alternative #4B. The estimated average annual operation and maintenance
costs range from $172,000 for Alternative #1 to $1,405,000 for Alternative #5A. The
estimated present worth ranges from $2,886,000 for Alternative #1 to $85,760,000 for
Alternative #4B.
The No Action Alternative (Alternative #1) has the lowest present worth as costs only
include those for continued contaminant monitoring, but would provide little protection of
human health and the environment. Alternatives #2 and #3 have the next lowest present
worth but rely heavily on institutional controls. The capital and present worth costs for
Alternative #4B ($82,720,000 and $85,760,000, respectively) are prohibitive. Alternative
#4A, the soil vapor extraction option, provides similar protectiveness at considerably lower
present worth cost ($20,467,000), but would take a longer time to implement. Both ground
water treatment Alternatives (Alternatives 5A and 5B) provide equal protection; however, the
operation and maintenance cost, a continuing expense, is considerably lower (1/3) for the UV
Photochemical oxidation treatment. Consequently, the alternatives which provide the most
treatment for the least cost are Alternative #4A (Soil Vapor Extraction) and #5B (UV
31
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Photochemical Oxidation).
The U.S. EPA has decided to combine components of both of these alternatives to form a
combination alternative that will address both contaminated soils which are the source of the
groundwater contamination and contaminated groundwater. The combined capital cost of
these two alternatives is $4,461,686 with an average annual Operation & Maintenance Cost
of $431,183. The Total Present Worth of the combined alternative is $11,754,246. This is
only slightly more than the total present worth of the groundwater alternative alone and it
results in the potential for completing the cleanup within 30 years as opposed to over 100
years if only groundwater extraction and treatment were performed.
STATE ACCEPTANCE
The State of Michigan agrees with the EPA's selected remedy at this Site.
COMMUNITY ACCEPTANCE
The community acceptance was evaluated based upon: the questions from the public during
the public meeting; the one verbal comment given at the public meeting; and, the written
comments submitted during the public comment period. Based upon the questions taken at
the public meeting, the community reaction towards the proposed remedy was mixed, some
for and some against. One written comment was against taking this action because the
commenter felt that the money it would take to implement and operate the remedial action,
approximately $11 million, could be better used to cure the people who became afflicted by
cancer as a result of the contamination. The written comments received during the comment
period followed this pattern: 1 supporting the U.S. EPA's selection, 1 against the U.S.
EPA's selection, and 1 that wanted more information before they could determine whether
the proposal was acceptable.
There appeared to be a consistent theme in the questions and comments received regarding a
statement in the Proposed Plan regarding the potential for a third operable unit. The scope
of the potential third operable unit is to address any new soil hot spots that are discovered in
the next phase of the PRPs' investigation. The PRPs are planning to install new borings and
monitoring wells in several other parts of the Site to determine if there are additional .
sources. The PRPs have already sent access agreements to numerous business owners
seeking their consent to perform this work. This has had the effect of engendering fear on
the part of these companies that they may at some point in time be asked to participate in the
cleanup action. Consequently, some members of the public who represent business interests
in Clare, are not in favor of undertaking the proposed remedy because of the potential cost
involved. However, there were members of the public who expressed their support of the
U.S..EPA's proposal during the question and answer session at the public meeting.
For more detailed responses to the public comments, refer to the attached Responsiveness
Summary .
32
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........
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The U.S. EPA's selected remedy is Alternative #4A (IN-SITU SOIL VAPOR
EXTRACTION) for the contaminated soil areas (See Figures 4, 5, & 6) and Alternative #5B
(EXTRACTION & TREATMENT USING UV PHOTOCHEMICAL OXIDATION) for the
contaminated groundwater (See Figure 7).
This remedy is necessary to meet the U.S. EPA's objective of restoring the only source of
groundwater for the population of Clare to its beneficial use as a drinking water supply
within a reasonable timeframe. If contaminated soils, which serve as a source of
contamination to' the aquifer, are not addressed along with the groundwater, the soils will
continue to leach contaminants into the groundwater and sustain the plume for over 100 .
years. Addressing the soils along with the groundwater could make it possible to cleanup the
aquifer within approximately 30 years.
The combined alternative will include use, deed and/or access restrictions as necessary;
diversion of the US 10 Drainage Ditch around contaminated sediments while the remedial
action is being conducted; Soil Vapor Extraction; ground water extraction and treatment
using ultraviolet photochemical oxidation. There are several additional engineering featu,res
that may be added to the component of this remedial action that addresses contaminated soils
based upon information to be obtained during pre-design activities. These enhancements may
include: limited excavation of "hot spots" where soil vapor extraction may not be practicable;
temporary capping of areas to be treated using soil vapor extraction to enhance the
effectiveness of this process; or, the addition of nutrients or oxygen to enhance
bacteriological degradation of VOCs. These modifications shall not be used as replacements
of the selected soil remedy, only as necessary to enhance its effectiveness and efficiency.
Under Alternative 5B, groundwater shall be extracted until Federal Maximum Contaminant
Levels (MCLs) Or non-zero Maximum Contaminant Level Goals (MCLGs), promulgated
under the Safe Drinking Water Act, and the groundwater cleanup standards derived under
Michigan Act 307, Type B criteria are met in the groundwater contaminant plume. (See
Table 4 for Groundwater Cleanup Standards.) The extracted groundwater shall be treated on
site using the UV Photochemical Oxidation System and discharged to injection wells located
upgradient from the site or discharged to the Tobacco River, in compliance with the
substantive requirements of a NPDES discharge permit, as administered by the State under
Part 21 of Michigan Act 245. The goal of this remedial action is to restore the groundwater
to. its beneficial use, which is, at this site, an actual drinking water source. Based on
information obtained during the RI and on a careful analysis of the remedial alternatives, the
U.S. EPA believes that the selected remedy will attain this goal. It may become apparent,
during implementation or operation of the groundwater extraction system, that contaminant
levels have ceased to decline and are. remaining constant at levels higher than the
Groundwater Cleanup Standards over some portion of the contaminant plume. In such a
case, the system performance standards, the system design, and/or the remedy may be
reevaluated. And, if such a reevaluation results in a determination that the Groundwater
Cleanup Standards can not be achieved, alternate groundwater cleanup standards will be
33
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considered by U.S. EPA, in consultation with MDNR.
Based upon the calculations of aquifer restoration time contained in the administrative record,
it is estimated that the Groundwater Cleanup Standards can be achieved in the groundwater
within 30 years if the soil contamination is addressed. System performance monitoring will
be performed on a regular basis. If warranted, the system may have to be modified in order
to achieve the cleanup goals. The following are examples of what might be required as
modifications to the system include, but are not limited to:
(a) Pumping may be discontinued at individual wells where Groundwater Cleanup Standards
have been attained;
(b) Wells may be pumped on an alternate basis to eliminate stagnation points;
(c) "Pulse pumping" may be performed to allow the aquifer to equilibrate and allow adsorbed
contaminants to partition into the groundwater for extraction; and
(d) Additional extraction wells may be installed to facilitate or accelerate cleanup of the
contaminant plume.
(e) Air Sparging or Bioventing (See Administrative Record Update #5 for more information
on this area of research) may be incorporated into the groundwater extraction system to
enhance the biodegradation and removal of volatiles. This technique has been used recently
at a growing number of contaminated groundwater sites with dramatic results.
Groundwater will be monitored periodically at any well where the Cleanup Standards appear
to have been achieved, and pumping has ceased, to ensure that Groundwater Cleanup
Standards continue to be met. A fence shall be maintained around the soil vapor extraction
system and the groundwater treatment system to prevent access to the site. .
The costs of implementing the combination of alternatives #4A and 5B is not the same as the
sum of the costs of the individual alternatives since they include some common cost elements
such as: Site preparation, diversion of the USIO drainage ditch, access restrictions, ground
water monitoring, labor, site inspections, etc. Also, some elements of the Soil Vapor
Extraction alternative that were included in the PRPs' cost estimates in the FS were
unnecessary and have been removed from the cost estimate for the combined alternative.
Consequently, the costs of the combination of alternatives are presented in this Record of
Decision (See Tables 8, 9, and 10) and were also presented in the Proposed Plan. The
Capital Cost is estimated at $4,461,686. The average annual Operation & Maintenance
Cost is estimated at $431,183. The Total Present Worth over 30 years using a 5% discount
rate is $11,754,247.
Based on current information, this combined remedy appears to provide the best balance of
trade-offs among the alternatives with respect to the nine criteria that U. S. EP A uses to
evaluate alternatives. .
34
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FIGURE 4
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TABLE 8 - CAPITAL COST FOR COMBINATION OF ALTERNATIVES 4A & 5B
CAPIT AL COSTS Ouantitv Unit Unit Price Total Cost
1. Site ~aration 1 Is $15,000.00 $15,000.00
Divert US 1 Drainaee Ditch
2. SVE Soil Treatment Systems ft $60.00
Wells 844 $50,640.00
Asphalt Cutting / Concrete Removal 2500 If $2.00 $5,000.00
Asphalt Removal 11 000 sf $0.45 $4,950.00
Asphalt/Concrete handling/disposal 285 ~r $40.00 $11,400.00
Asphalt Replacement 11 000 $3.90 $42,900.00
Concrete Cutting 1400 If $6.00 $8,400.00
Concrete Replacement 2080 sf $9.00 $18,720.00
Trenching 720 If $8.00 $5,760.00
Perforated Pipe 720 If $5.00 $3,600.00
Well heads 39 ea $400.00 $15,600.00
Extraction riping 2650 If $16.40 $43,460.00
Mechanica equipment 1 Is $106,000.00 . $106,000.00
Buildings 1500 sf $40.00 $60,000.00
Piping subfloor 15000 sf $20.00 $300,000.00
1800 # Carbon units 48 ea $8,000.00 $240,000.00
Analytical testing for carbon 19 Is $1,500.00 $28,500.00
Dewatering wells 18 ea $1,000.00 $18.000.00
Carbon adsorption dewatering 8 ea $10,000.00 $80,000.00
Electrical. 1 Is $60,000.00 $60,000.00
Pilot Study 1 Is $75,000.00 $75,000.00
3. Access Restrictions
Fencing 2450 If $14.00 $34,300.00
Gate 5 ea $700.00 $3.500.00
Signs 49 ea $50.00 $2.450.00
Deed Restrictions
4. Gr. Water Wells & Injection 3735
Asphalt Cutting If $2.00 $7,470.00
Asphalt Removal 5602 sf $0.45 $2,520.00
Asphalt handling/disposal 104 ~l $40.00 $4,160.00
Asphalt Replacement 5602 $3.90 $21,847.80
Electrical installation 8 Is $10,000.00 $80,000.00
Wells 560 ft $200.00 $112.000.00
Extraction well piping 3147 ft $37.00 $116,439.00
~ection well plpmg 2830 ft $37.00 $104,710.00
ell heads 8 ea $400.00 $3,200.00
Well development 8 ea $2,000.00 $16,000.00
Well pumps 8 ea $1,500.00 $12,000.00
Instrumentation. 1 Is $30,000.00 $30,000.00
Railroad Track Crossings 4 ea $15,000.00 $60,000.00
S. Ground Water Treabnent
100 mm UV/Oxidation Unit 2 Is $267.800.00 $535,600.00
6. Ground Water Monitoring Is $1,000.00 $1,000.00
MobiliutionlDemobiliution 1
Drilling 874 If $100.00 $87,400.00
Well Development/screening 28 ea $1,800.00 $50,400.00
Bladder pumps 6 ea $600.00 $3,600.00
7. Contingencies 25% $656,382.00
General
Health & Safetv Protection 10% $262,552.77
8. Other
Permitting $75,000.00
Administration 5% $177,223.12
9. Engineering $300,000.00
Design Services
Construction Services $365,000.00
TOTAL CAPITAL COSTS $ 4,461.685.51
37
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TABLE 9
OPERATION & MAINTENA~\ OSTS
COMBINATION OF ALTERNATI\ j 4A + 5B
CLARE WATER SUPPLY SiTE
Operation & Maintenance. Quantity Unit Uilit Total Years
Price. Cost
Annual Operation SVE System
a. Operation 1 Is $205,000.00 $205,000.00
b. Labor 1000 hr $65.00 $65,000.00
c. Project Management 250 hr $100.00 $25,000.00
d. Carbon dewatering 8 ea $10,000.00 $80,000.00
SUBTOTAL $375,000.00
Annual Operation OW System
a. Electricity & Chemicals 365 day $150.00 $54,750.00
b. System Operation 1000 hrs $45.00 $45,000.00
c. System Maintenance 8 days $400.00 $3,200.00
d. UV Lamp Replacement 200 lamps $60.00 $12,000.00
SUBTOTAL $114,950.00
Annual maintenance
a. Mowing 2 ac $700.00 $1,400.00
b. Erosion Repair 2 ac $250.00 $500.00
c. Fencing Repair 1 If $1,000.00 $1,000.00
SUBTOTAL $2,900.00
Variable replacement
a. Refurbish wells 1 Is $19,000.00 $19,000.00 10,20,30
b. Replace Bladder pumps 6 ea $600.00 $3,600.00 5,10,15,20,25,30
c. Replace 4 ext. pumps 4 ea $1,500.00 $6,000.00 5,10,15,20,25,30
d. Replace 4 ext. wells 4 ea $800.00 $3,200.00 20
e. Replace 4 inj. pumps 4 ea $1,500.00 $6,000.00 5,10,15,20,25,30
f. Replace 4 inj. welIs 4 ea $800.00 $3,200.00 20
g. Confirmatory Sampling 1 Is $48,000.00 $48,000.00 5
SUBTOTAL $89,000.00
Annual Monitoring
a. Sampling/shipping 4 ea $2,000.00 $8,000.00
b. Monitoring wells 90 ea $1,000.00 $90,000.00
c. comprehensive sampling 30 ea $1,500.00 $45,000.00
d. Surface Water Sampling 5 ea $1,500.00 $7,500.00
e. Extraction well samples 36 ea $1,000.00 $36,000.00
f. Injection well samples 36 ea $1,500.00 $54,000.00
g. Annual Report 1 ea $3,500.00 $3,500.00
SUBTOTAL $244,000.00
.AVERAGE'ANNtJALO&M:... .
... :..: . : .. $431,183
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TABLE 10
CALCULATION OF PRESENT WORm COSTS
COMBINATION OF ALTERNATIVES 4A + 5B
YEAR ANNUAL O&MCOST DISCOUNT RATE PRESENT WORm
5%
1 736850 0.9524 $701,776
2 736850 0.9070 $668,323
3 736850 0.8638 $636,491
4 736850 0.8227 $606,206
5 800450 0.7835 $627,153
6 361850 0.7462 $270,012.
7 361850 0.7107 $257,167
8 361850 0.6768 $244,900
9 361850 0.6446 $233,249
10 396450 0.6139 $243,381
11 361850 0.5847 $211,574
12 361850 0.5568 $201,478
13 361850 0.5303 $191,889
14 361850 0.5051 $182,770
15 377450 0.4810 $181,553
16 361850 0.4581 $165,763
17 361850 0.4363 $157,875
18 361850 0.4155 $150,349
19 361850 0.3957 $143,184
20 402850 0.3769 $151,834
21 361850 0.3589 $129,868
22 361850 0.3418 $123,680
23 361850 0.3256 $117,818
24 361850 0.3101 $112,210
25 377450 0.2953 $111,461
26 361850 0.2812 $101,752
27 361850 0.2678 $96,903
28 361850 0.2551 $92,308
29 361850 0.2429 $87,893
30 396450 0.2314 $91.,739
CAPITAL COST $ .:4,461,686q
A VERAGE ANNUAL O&M q . q.... $ ... 431,183
TOTAL PRESENT WORTH . q $ 11,754,246
. - --.
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STATUTORY DETERMINATIONS
Under its legal authorities, EPA's primary responsibility at Superfund sites is to undertake
remedial actions that achieve adequate protection of human health and the environment. In
addition, Section 121 of CERCLA establishes several other statutory requirements and
preferences. These specify that when complete, the selected remedial action must comply
with ARARs under Federal and State environmental laws, unless a statutory waiver is
justified. The selected remedy must also be cost effective and utilize permanent solutions
and alternative treatment or resource recovery technologies to the maximum extent
practicable. Finally, the statute includes a preference for remedies that employ treatment that
permanently and significantly reduce the toxicity, mobility or volume of hazardous
substances, pollutants and contaminants. The following sections discuss how the selected
ren:-edy, where applicable, meets the statutory requirements and preferences.
A.
Protection of Human Health and the Environment
The selected remedy will provide for protection of human health by remediating
contaminated soils which would continue to leach into groundwater and contaminate a
drinking water aquifer, and by remediating the contaminated groundwater.
The selected remedial alternatives are proven and reliable methods for removing Volatile
Organic Compounds (VOCs) from both soils and groundwater. The remedial objective of
this operable unit is to restore both the contaminated site soils and the groundwater aquifer to
health based cleanup levels for all contaminants of concern. The first operable unit, the air
stripping of the city water supply, will continue to operate in concert with the remedial
alternative selected in this Record of Decision until all cleanup objectives are achieved. If
additional sources of soil contamination are identified, a third operable unit will then address
those areas. .
Implementation of the selected alternative will reduce and control potential risks to human
health posed by exposure to contaminated groundwater and contaminated soil/sediment.
Extraction and treatment of contaminated groundwater to meet Groundwater Cleanup
Standards will reduce the potential excess lifetime cancer risk due to ingestion of
contaminated. groundwater from the unacceptable risks currently posed (e.g., 8 x l(4) by
groundwater contaminants to a maximum risk for individual carcinogenic chemicals of
approximately 1 x l~. If all carcinogens were treated to the 1 x l~ level for the individual
carcinogenic chemicals, the maximum cumulative risk would be approximately I x HtS,
which is an acceptable level.
Institutional controls will provide short-term effectiveness for tlte prevention of drinking
contaminated groundwater until the Groundwater Cleanup Standards are met. Air monitoring
will be conducted during the remediation to ensure that air quality is not adversely impacted
by the remedial action. The selected remedy also protects the environment by reducing the
potential risks posed by site chemicals discharging to the wetlands (by discharge to the U.S.
10 Drainage Ditch, which empties into the wetlands area) and to surface water (the Tobacco
40
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River).
Treatment of contaminated soil/sediment by Soil Vapor Extraction, in addition to reducing
any potential further risk posed by direct contact exposure to contaminated soil/sediment, will
reduce groundwater contaminant loading to the usable aquifer allowing the restoration of the
aquifer within a reasonable time frame.
No unacceptable short-term risks will be caused by implementation of the remedy. The
community and site workers may be exposed to noise and dust nuisances during construction
of the soil vapor extraction and groundwater extraction systems. Mitigative measures will be
taken during remedy construction activities to minimize the noise and dust impacts of
construction upon the surrounding community.
Soil Vapor Extraction and groundwater treatment using UV-photochemical oxidation should
not present short-term risks due to VOC air emissions if properly designed and monitored.
Standard safety programs should manage any short-term risk of accidents.
B.
Compliance with Applicable or Relevant and Appropriate Requirements (ARARs)
The selected remedy is designed to meet all applicable or relevant and appropriate
requirements (ARARs) of Federal and more stringent state environmental laws. The
following discussion provides details of ARARs that will be met by the selected alternative.
a. Chemical-s,pecific ARARs
Chemical-specific ARARs regulate the release to the environment of specific substances
having certain chemical characteristics. Chemical-specific ARARs typically determine the
extent of cleanup at a site.
i. Soils/Sediments
No Federal chemical-specific standards exist for soils and sediments.
The Michigan Environmental Response Act 307 of 1982, as amended (Act 307), provides for
the degree of cleanup of contaminated sites within the State; therefore, Act 307 is applicable
or relevant and appropriate to the Clare Water Supply Site. The U.S. EPA considers the
substantive portions of the Act 307 rules to be ARARs for the remedial action at this site.
These rules provide, inter itii, that remedial actions shall be protective of human health,
safety, the environment, and the natural resources of the State. To achieve the standard of
protectiveness, Act 307 rules specify that a remedial action shall achieve a degree of cleanup
under either Type A (cleanup to background levels), Type B (cleanup to risk-based levels),
or Type C (cleanup to risk-based levels under site-specific considerations) criteria.
The U.S. EPA has determined that the appropriate cleanup standards for soils and sediments
would be derived under Type B criteria. This determination is based upon the consideration
41
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of projected land use in the Clare area and of protection of the environment. The Type B
criteria for carcinogens are based on the reduction of the concentrations of hazardous
substances to levels which pose an individual excess lifetime cancer risk of I x 10-6, using
the standardized exposure assumptions in the rules.
The U.S. EPA has determined that application of Type B criteria would be the appropriate
cleanup response for the contaminated soils. and sediments up to 25 feet in depth since these
soils, which constitute the primary source, are within the unsaturated zone or will be able to
be dewatered. Soils located at depths greater than 25 feet are in continuous contact with
groundwater. These saturated soils will not be amenable to treatment using Soil Vapor
Extraction because of the difficulty in dewatering saturated soils below this depth. However,
since the soil cleanup standards are intended to be protective of groundwater, the measure of
whether or not soils have been remediated adequately will be the achievement and
maintenance' of groundwater cleanup levels. In the event that groundwater cleanup levels are
not being maintained or significantly reduced after the soil vapor extraction activity has
exhausted its ability to extract volatile organics from the soil, an enhancement to the soil
vapor extraction system, including but not limited to, in-situ bioremediation, steam injection
or air sparging shall be evaluated and considered for addition to the remedy.
ii. Groundwater
Federal ARARs
Maximum Contaminant Levels (MCLs) and, to a certain extent, Maximum Contaminant
Level Goals (MCLGs), the Federal drinking-water standards promulgated under the Safe
Drinking Water Act (SDW A), are applicable to municipal water supplies servicing 25 or
more people. At the Clare Water Supply Site, MCLs and MCLGs are applicable or relevant
and appropriate, since the aquifer is a Class I source which is being used for drinking water
in Clare. MCLGs are relevant and appropriate when the standard is set at a level greater
than zero (for non-carcinogens), otherwise, MCLs are relevant and appropriate. The area of
compliance for Federal drinking-water standards is anywhere within the area of the
contaminant plume.
At the Clare Water Supply Site, the U.S. EPA has determined that cleanup to MCLs and
non-zero MCLGs would not be protective, since the residual risk would fall outside of the
range the U.S. EPA considers to be protective. Consequently, risk-based cleanup standards
are necessary to achieve protectiveness.
State ARARs
The State of Michigan is authorized to administer the implementation of the Federal SDW A.
The State has also promulgated MCLs under Michigan Act 399 (the Michigan Safe Drinking
Water Act). Act 399 is applicable to the site since the aquifer is currently being utilized by
the municipal water supply and because the affected homes and businesses are connected to
the municipal water supply.
42
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As above, Michigan Act 307 is applicable or relevant and appropriate to the Clare Water
Supply Site. The U.S. EPA has determined that standards for groundwater cleanup, that are
found under the Type B criteria, would be protective.
Finally, the upper aquifer discharges groundwater to the surface at a point shown in Figure
3. The U.S. EPA has determined that Type B criteria would provide for the protection of
surface water quality, in turn, protecting human health and the environment. There are
several compounds for which such discharge has a more stringent standard as discussed
above in the section of this ROD entitled "Cleanup Levels Where Groundwater Discharges to
Surface Water" and Table 5. The chosen remedy will attain these standards.
iii. Surface Water
Federal ARARs
Surface water quality standards for the protection of human health and aquatic life were
developed under section 304 of the Clean Water Act (CW A). The Federal Ambient Water
Quality Criteria (A WQc) are nonenforceable guidelines that set pollutant concentration limits
to protect surface waters that are applicable to point source discharges, such as from
industrial or municipal wastewater streams. At a Superfund site, the Federal A WQC would
not be applicable except for pretreatment requirements for discharge of treated water to a
Publicly Owned Treatment Works (POTW). CERCLA (section 121(d)(I» requires the U.S.
EP A to consider whether A WQC would be relevant and appropriate under the circumstances
of a release or threatened release, depending on the designated or potential use of
groundwater or surface water, the environmental media affected by the releases or potential
releases, and the latest information available. Since the aquifer is a current and potential
source of drinking water and since treated water may be discharged to the Tobacco River or
to injection wells (if treatment criteria are met), A WQC adopted for drinking water and
A WQC for protection of freshwater aquatic organisms are relevant and appropriate to the
point source discharge of the treated water into the Tobacco River.
State ARARs
Portions of the Water Resources Commission Act 245 (Michigan Act 245) of 1929, as
amended, establish surface water-quality standards to protect human health and the
environment. The State administers the NPDES program under Part 21 of Michigan Act
245; therefore, Part 21 of Act 245 would be applicable to the direct discharge of treated
water to the Tobacco River or to a clean aquifer, to the indirect discharge through
groundwater movement to a surface water body, or to discharge to a POTW.
b. Location-specific ARARs
Location-specific ARARs are those requirements that relate to the geographical position of a
site. These include: .
43
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Federal ARARs
Both RCRA (40 CFR 264. 18(b) - hazardous waste storage - flood plain) and Executive Order
11988 - Protection of Flood Plains - are relevant and appropriate for this site, a portion of
which is located within the mapped 1oo-year flood plain of the Clinton River. These
regulations would require that the groundwater .treatment system be located above the 100-
year flood plain elevation (826.3 feet above mean sea level for the Tobacco River in Clare)
and be protected from erosional damage. The regulations also require that any portion of a
cap that is constructed within the 1oo-year flood plain be adequately protected against a 100-
year flood event (e.g., geotextiles should be used to secure topsoil, etc.)
Section 404 of the CW A regulates the discharge of dredged or fill material to waters of the
United States, including wetlands. A portion of the Clare Water Supply Site includes
wetlands which are regulated under section 404 of the CW A; therefore, the substantive
requirements of section 404 would be relevant and appropriate to the remedial action at the
site.
Executive Order 11990 - Protection of Wetlands - is an applicable requirement to protect
against the loss or degradation of wetlands. As presented above, implementation of the
groundwater extraction system could potentially have a negative impact on the wetlands at
the Clare Water Supply'Site. The scope of the impact has not yet been determined however
monitoring of the integrity of the wetlands shall be implemented along with this remedial
action. Mitigative efforts would be applied to the cleanup if an impact is seen on the
wetlands. In the event of a negative impact upon the wetlands, Executive Order 11990 may
require these resources to be replaced.
State ARARs.
The Goemaere-Anderson Wetland Protection Act 203 of 1979 (Act 203) regulates any
activity which may take place within wetlands in the State of Michigan. Act 203 is
applicable to the remedial action at the Clare Water Supply Site; it may also require the
replacement of adversely impacted wetlands with comparable resources.
The Inland Lakes and Streams Act 346 of 1972, as amended, regulates inland lakes and
streams in the State. Act 346 would be applicable to any dredging or filling activity on the
Tobacco River bottom1ands.
The Soil Erosion and Sedimentation Control Act 347 of 1972 regulates earth changes,
including cut and fill activities, which may contribute to soil erosion and sedimentation of
surface waters of the State. Act 347 would apply to any such activity where more than 1
acre of land is affected or the regulated action occurs within. 500 feet of a lake or stream.
Act 347 would be applicable or relevant and appropriate to remedial action activities should
these actions impact the Tobacco River, which is less than 500 feet from the Clare Water
Supply Site.
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c. Action-~pecific ARARs
Action-specific ARARs are requirements that define acceptable treatment and disposal
procedures for hazardous substances.
Federal ARARs
RCRA requirements are applicable to the soil contaminated with RCRA-listed or
characteristic hazardous wastes when the soils are excavated and managed (treated, disposed,
or stored), as defined by RCRA, during the cleanup. RCRA Land Disposal Restrictions
(LDR or Land Ban) would not be applicable as long as no "placement" of the material occurs
at this site. However, if implementation of Alternative #4A brings contaminated soil to the
surface, either returned by the augers or excavated from the trenches, which can not be
managed and treated within the area of contamination, and this material has to be moved
from that area of contiguous contamination and be treated, stored or disposed of elsewhere,
then the LDRs will be applicable to that material.
In its pure form, waste organic solvent may be a characteristic waste (ignitibility) and, in its
present form (mixed with soil and debris), the waste solvents would be expected to fail the
TCLP test; and therefore, exhibit a property of characteristic waste. As of this date, no
testing has shown that the Clare Water Supply Site wastes exhibited a property of
characteristic waste as defined by RCRA using the TCLP test for organics. RCRA Subtitle
C requirements, including LDR, will be relevant and appropriate if the solvent wastes are
excavated and managed assuming they are RCRA wastes.
The selected remedy may also require storage or disposal of hazardous waste because the
groundwater treatment system or soil vapor extraction system may require emission control
units to capture or contain volatile organics derived from aeration of the contaminated
groundwater or soil. The RCRA waste generation and temporary storage regulations under
40 CFR Part 262 would Uten be applicable to that action. For example, activated carbon
canisters utilized as emission controls would be managed, when spent, as a characteristic
waste if the waste canisters were to fail the TCLP test.
Additional Federal action-specific ARARs are found in the FS.
State ARARs
The State of Michigan is authorized to administer RCRA within the State. Under the
Hazardous Waste Management Act 64 of 1979, as amended, the State regulates the
generation, tranSport, treatment, storage, and disposal of hazardous waste. Act 64 also
regulates the closure, and the postclosure care, of hazardous waste disposal facilities in the
State. As. with RCRA, above, Act 64 is applicable to the treatment or storage of hazardous
landfIll contents and/or hazardous residuals from on-site treatment units.
Parts 4, 9, and 21 of the Water Resources Commission Act 245 of 1929, as amended,
establish rules for water quality by prohibiting injurious discharges to surface water. These
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rules would be applicable to the discharge of treated groundwater to the Tobacco River or to
the injection wells.
As described earlier in this document, the Michigan Environmental Response Act 307 of
1982, as amended (Act 307), provides for the degree of cleanup of contaminated sites within
the State. The U.S. EPA has determined that the substantive portions of the Act 307 rules
are applicable or relevant and appropriate to the Clare Water Supply Site. The Act 307 rules
require that remedial actions shall be protective of human health, safety, the environment,
and the natural resources of the State. To achieve this standard of protectiveness, the Act
307 rules require that a remedial action achieves a degree of cleanup under either Type A
(cleanup to background levels), Type B (cleanup to risk-based levels), or Type C (cleanup to
risk-based levels under site-specific considerations) criteria.
C.
Cost-Effectiveness
Cost-effectiveness compares the effectiveness of an alternative in proportion to its cost of
providing environmental benefits. Table 7 lists the costs associated with the implementation
of the remedies. .
The selected remedy is cost-effective. The combined remedy of Alternatives #4A and #5B
provide for the maximum use of treatment of all the alternatives for a capital cost of
$4,267,063 and average annual operation and maintenance costs of $ 431,582.
D.
Utilization of Permanent Solutions and Alternative Treatment Technologies to the
Maximum Extent Practicable
The selected remedy utilizes permanent solutions and alternative treatment technologies to the
maximum extent practicable (MEP) at this time. This finding was made after evaluation of
the protective and ARAR-compliant alternatives for the Clare Water Supply Site remedial
action and comparison of the "trade-offs" (advantages versus disadvantages) among the
remedial alternatives with respect to the five balancing criteria (see above).
The NCP established the U.S. EPA policy of giving priority to long-term effectiveness and
to reduction of toxicity, mobility, and volume (TMV) at a site, stating that long-term
effectiveness and reduction of TMV through treatment are generally the key decisional
factors to be considered at Superfund sites. Once the threshold criteria of protection of
human health and the environment and ARARs-compliance were satisfied, a key criterion
used in remedy selection for the Clare Water Supply Site was short-term effectiveness, rather
than an emphasis on the immediate reduction of TMV through treatment. Long-term
effectiveness was also emphasized by providing for acceptable residual risk levels in the
groundwater and soils at the site.
U.S. EPA and the State of Michigan have determined that the selected remedy represents the
maximum extent to which permanent solutions can be utilized in the most cost effective
manner to address soil and ground water contamination in the affected area. Of the
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alternatives that are protective of human health and the environment and comply with
ARARs, U.S. EPA and the State have determined that the selected remedy provides the best
balance of tradeoff in terms of protectiveness, long-term effectiveness, short-term
effectiveness, implementability and cost.
The remedial alternatives selected in this Record of Decision address the reduction in
toxicity, mobility or volume achieved through treatment and the statutory preference for
treatment as a principal element of the selected remedy.
E.
Preference for Treatment as a Principal Element
The principal threats at the Clare Water Supply Site is the solvent and oil-contaminated soils
and sediments, since the contaminants are highly concentrated and would continue to leach
into the groundwater if left untreated.
The selected remedial alternative achieves to the maximum extent possible treatment of all
VOCs which are removed from the soils and groundwater. The soil treatment system will
rely upon vapor phase carbon adsorption and off-site thermal destruction of the VOCs while
the groundwater treatment system will rely upon photochemical oxidation to destroy all the
VOCs removed from the groundwater at the site. The component of the selected remedy for
soils (Soil Vapor Extraction) also treats more contaminated soil than the other soils
alternative since SVE can be performed on contaminated soils located under buildings while
the excavation alternative (4B) will not be able to treat the contaminated soils which are
located under buildings (roughly 15,000 cubic yards).
Alternative 4A treats the soil/sediment principal threat and Alternative 5B addresses the
contaminated groundwater primary risk through treatment. Consequently, the combined
remedy selected for the Clare Water Supply Site fully satisfies the statutory preference for
treatment as a principal element of the remedy.
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