PB95-964108
EPA/ROD/R05-95/280
February 1996
EPA Superfund
Record of Decision:
Muskego Sanitary Landfill,
Muskego, WI
2/2/1995
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DECLARATION
RECORD OF DECISION
SELECTED REMEDIAL ALTERNATIVE FOR
GROUNDWATER FINAL REMEDY
FOR MUSKEGO SANITARY LANDFILL
Site Name and Location:
Muskego Sanitary Landfill
Muskego, Wisconsin
Statement of Basis and Purpose:
This decision document presents the selected remedial action for
the Muskego Sanitary Landfill located in Muskego, Wisconsin. The
decision has been developed in accordance with the Comprehensive
Environmental Response, Compensation, and Liability Act (CERCLA) ,
as amended by the Superfund Amendments and Reauthorization Act
(SARA) , and in accordance with the National Oil and Hazardous
Substances Pollution Contingency Plan (NCP) to the extent
practicable. The attached index identifies the items that
comprise the Administrative Record, upon which the selection of
the remedial action is based.
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 Record of Decision (ROD), may present an
imminent and substantial endangerment to public health, welfare
or the environment.
Description of the Selected Remedy:
The Final Remedy addresses protection of ground water and
potential exposure to ground water through engineering controls.
Institutional controls have already been initiated through the
interim source control action. The principal threats are direct
exposure to contaminated groundwater through ingestion or
inhalation at private wells. This remedy is described as
follows:
o Monitor groundwater throughout the site,
o Conduct a groundwater pumping test(s),
o Install and operate groundwater extraction in the vicinity
of the Non-Contiguous Fill Area,
o Perform on-site treatment and discharge of extracted
groundwater from the Non-Contiguous Fill Area,
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o Discharge treated water to an on-site infiltration basin in
accordance with state standards, and
o Dispose of treatment residuals, if generated, to an approved
disposal facility.
o Monitoring and evaluation of the effectiveness of the
groundwater extraction system in achieving progress toward
cleanup standards, and
o Expansion of the system if data on the performance of the
system indicates that expansion is necessary to make
progress toward cleanup standards:
State Concurrence:
The State of Wisconsin concurs with the selected remedy. The
letter of concurrence is attached to the Record of Decision (ROD)
package.
Declaration:
The selected remedy is protective of human health and the
environment, attains Federal and State requirements that are
legally applicable or relevant and appropriate to the remedial
action, and is cost-effective. This remedy utilizes permanent
solutions and alternative treatment technology to the maximum
extent practicable for this site. .Because this remedy will
result in hazardous substances remaining on-site above the
health-based levels, a review will be conducted within 5 years
after commencement of remedial action, to ensure that the remedy
continues to provide adequate protection of human health and the
environment.
Datef . / Valdas V. Adamkus^
Regional Administrator
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SUMMARY OF REMEDIAL ALTERNATIVE SELECTION
MUSKEGO SANITARY LANDFILL SITE
MUSKEGO, WISCONSIN
TABLE OF CONTENTS
I. SITE NAME AND LOCATION 1
II. SITE HISTORY AND ENFORCEMENT ACTIVITIES 3
III. COMMUNITY PARTICIPATION. , 6
IV. SCOPE OF GROUNDWATER REMEDIAL ACTION 7
V. SITE CHARACTERISTICS 8
VI. SUMMARY OF SITE RISKS 14
VII. DESCRIPTION OF ALTERNATIVES 21
VIII. SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES 30
IX. THE SELECTED REMEDY 39
X. STATUTORY DETERMINATIONS 42
XI. RESPONSIVENESS SUMMARY 47
XII. INTERIM GROUNDWATER MONITORING PLAN Attachment A
XIII. PERFORMANCE EVALUATIONS OF PUMP & TREAT Attachment B
XIV. ADMINISTRATIVE RECORD Attachment C
XV. STATE CONCURRENCE LETTER Attachment D
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DESCRIPTION OF FIGURES
MUSXEGO SANITARY LANDFILL SITE
MUSKEGO, WISCONSIN
FIGURE 0
FIGURE 1
FIGURE 2
FIGURE 3
FIGURE 4
FIGURE 5
FIGURE 6
FIGURE 7
FIGURE 8
SITE LOCATION MAP
SITE MAP
WASTE MANAGEMENT OF WISCONSIN, INC. PROPERTY
WATER TABLE MAP
SAMPLING LOCATIONS (SOUTHERN FLOW PATH)
SAMPLING LOCATIONS (SOUTHEAST FLOW PATH)
SAMPLING LOCATIONS (NON-CONTIGUOUS FILL AREA)
SAMPLING LOCATIONS (NORTHERN PERIMETER)
SAMPLING LOCATIONS (PRIVATE WELLS)
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TABLE 1
TABLE 2
TABLE 3
TABLE 4
TABLE 5
TABLE 6
TABLE 7
TABLE 8
TABLE 9
TABLE 10
DESCRIPTION OF TABLES
MUSKEGO SANITARY LANDFILL SITE
MUSKEGO, WISCONSIN
ORGANIC GROUP RESULTS. ROUNDS 1 AND 2 GROUNDWATER
SAMPLES
NR 140 AND EPA MCL EXCEEDANCES FOR GROUNDWATER IN
SOUTHERN FLOW PATH
NR 140 AND EPA MCL EXCEEDANCES FOR GROUNDWATER IN
SOUTHEAST FLOW PATH
NR 140 AND EPA MCL EXCEEDANCES FOR GROUNDWATER IN
NON-CONTIGUOUS FILL AREA/ANAMAX FACILITY
NR 140 AND EPA MCL EXCEEDANCES FOR GROUNDWATER IN
NORTHERN WELLS
POTENTIAL EXPOSURE PATHWAYS FOR FUTURE LAND USE
EXPOSURE PARAMETERS FOR INGESTION OF GROUNDWATER BY
RESIDENTS - FUTURE LAND USE CONDITIONS
EXPOSURE PARAMETERS FOR INHALATION OF VOLATILES
FROM SHOWERING BY RESIDENTS - FUTURE LAND USE
CONDITIONS
SUMMARY OF POTENTIAL HEALTH RISKS - FUTURE LAND USE
CONDITIONS
COST SUMMARY - ALTERNATIVE 3 - THE SELECTED REMEDY
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SUMMARY OF FINAL REMEDIAL ACTION
GROUNDWATER REMEDY
MUSKEGO SANITARY LANDFILL SITE
MUSKEGO, WISCONSIN
I. SITE NAME AND LOCATION
The Muskego Sanitary Landfill Superfund site occupies approximately
56 acres north of State Highway 24 (Janesville Road), and east of
Crowbar Road in the City of Muskego, Waukesha County, Wisconsin.
The site is located in Southeastern Wisconsin approximately fifteen
miles southwest of the City of Milwaukee (see Figure 0) . More
specifically the site is southwest of the urbanized portions of the
City of Muskego by roughly three miles. The Site includes three
areas known as the "Old Fill Area", the "Southeast Fill Area" and
the "Non-Contiguous Fill Area" (see Figure 1) . The site also
includes wastewater ponds associated with a former rendering plant
complex (the "Anamax plant"). Portions of the property associated
with the Anamax plant are also included in the Old and Southeast
Fill Area boundaries. Directly north of the site is the Stoneridge
Landfill, a closed and covered solid waste landfill, that is not
part of the Superfund site. Land use to the west of the site is
for sand and gravel excavation. To the south, east and north of
the site, the land use is a combination of residential and
agricultural. The area surrounding the Site is semi-rural, but is
zoned to permit further development in the future. Several homes
and businesses are_in the vicinity of the property, and many were
once served by individual private water supply wells. In the late
1980s, city water mains were extended into the area and several
homes and businesses were connected. Currently, two residences
southeast of the site are not connected to public water. These
residences are indicated in Figure 1.
The Muskego Sanitary Landfill Site is situated on unconsolidated
deposits that are up to 300 feet thick and are generally comprised
of glacial till, outwash, and lacustrine deposits. Site
investigative information and private well boring logs show layers
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of fine-grained material (till and lacustrine deposits) south and
east of the site to depths of about 70 to 200 feet and coarse
grained material (outwash) below the till to depths of about 200 to
300 feet below land surface.
There are three principal sources of groundwater in Waukesha
County. In order of depth below the land surface they are: sand
and gravel within the glacial drift, Niagara dolomite, and an
underlying sandstone. In the Muskego area, a majority of the
private wells are finished in the thick sand and gravel deposits.
The water table for this shallow aquifer is approximately 20 to 40
feet deep and has produced yields as high as 2,000 gal/min. The
depth of the upper glacial drift is about 300 feet which
corresponds to the aquifer thickness. The groundwater
classification for this aquifer is Class IIA (i.e., is used for
human consumption purposes and is not restricted).
In the Muskego area, groundwater flow in the water table shallow
aquifer is generally in an easterly to southeasterly direction.
This is similar to the groundwater flow at the site, which has two
flow paths. The first is in a north to south direction under the
eastern portion of the Old Fill Area where the basal clay unit
separates the sand and gravel unit from the landfill. The second
flow path is generally to the southeast under the Southeast and
Non-Contiguous Fill Areas. These flowpaths are separated by a
groundwater divide that was created by the advancement of the Oak
Creek Till formation from the east. A sand and gravel seam to the
southeast is separated from the larger outwash to the south and
west of the site by the more impermeable clay layer.
The site is located within the Fox River watershed, just south of
a local surface divide. There are numerous wetlands in the area
and the closest off site intermittent stream is located about
three-quarters of a mile to the southeast. None of the wetlands
are located, within the site boundaries. Surface drainage at the
site is divided between flow to the wetlands and the intermittent
stream to the southeast. Surface water runoff from the Old Fill
Area is to the ditch along Crowbar Road or to the southeast through
a small swale. The western half of the Southeast Fill Area also
drains to this swale which eventually discharges to a small wetland
north of an abandoned railroad right-of-way. Runoff from the
neighboring Anamax property, the Non-Contiguous Fill Area,
Stoneridge Landfill, and the eastern half of the Southeast Fill
Area is toward the ditch along the service road to a small wetland
southeast of the site and then through a culvert under Highway 24
to a larger wetland. The site is located within the 100 year
floodplain.
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II. SITE HISTORY AMD ENFORCEMENT ACTIVITIES
A. Site History
The 38-acre Old Fill Area accepted material from the mid-1950s
until 1977. An unknown amount of waste oils, paint products, and
other wastes were deposited into the Old Fill Area during this
time. The Southeast Fill Area which covers about 16 acres,
accepted only municipal wastes during its operation from 1977 to
1981. The Non-Contiguous Fill Area includes a drum trench, north
and south refuse trenches, and an L-shaped fill 'area. This Non-
Contiguous Fill Area occupies approximately 4.2 acres northeast of
the Old Fill Area. Based on information from workers employed
during operation of the landfill, the L-shaped Fill Area is
expected to contain waste similar to that in the Old Fill Area.
In response to deteriorating water quality at on-site groundwater
monitoring wells, sampling of off site private water supply wells
was conducted in 1982 and 1984 by the site operator, Waste
Management of Wisconsin, Inc. (WMWI) , and Wisconsin Department of
Natural Resources (WDNR). The results of these analyses indicated
that several of the private wells may have been impacted by a
source of contamination, which could have been the landfill and/or
the Anamax wastewater lagoons. The results were based on elevated
indicator parameters. The test for indicator parameters is a
preliminary test completed to show signs of groundwater
contamination. In 1986 public water was extended to this area and
private wells in the area were connected to this supply. The site
was evaluated and ranked by the United States Environmental
Protection Agency (U.S. EPA) and placed on the National Priorities
List (NPL) on September 18, 1985.
In 1985, a partial methane extraction system was' installed by WMWI
along the western portion of the Old Fill Area to alleviate methane
gas migration that was noted at the site. The extracted gas is
destroyed through flaring.
B. Response Actions
During preparation of a portion of the Phase I Stoneridge Landfill
area called Module III, which is due east of the Non-Contiguous
Fill Area, buried drums were discovered in a pit. The drums and
contaminated soils were excavated by Chemical Waste Management,
Inc., under the supervision of WDNR,. and transported to the Adams
Center Landfill in Ft. Wayne, Indiana. Also liquid wastes from the
excavation and drums were transported to the SCA Incinerator in
Chicago, Illinois. The contaminated soils were excavated until
contaminant concentrations in subsequent soil samples were below
action levels established by WDNR.
During the Remedial Investigation (RI), a trench was discovered in
a portion of the Non-Contiguous Fill Area that contained a large
concentration of 55-gallon drums. The boundary of this Drum Trench
area was further defined using a magnetometer metal detector.
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Through a Unilateral Administrative Order issued on January 4,
1991, U.S. EPA ordered WMWI to remove the drums and surrounding
contaminated soils. WMWI proceeded to conduct this removal under
U.S. EPA's supervision. Excavation of the drum trench began in
April 1991 and was completed in May 1991. A total of 989 drums
were excavated along with approximately 2,500 cubic yards of
surrounding contaminated soil. The soils were excavated down to a
depth of approximately 25 feet below the original surface elevation
until groundwater was encountered.
The drum trench was re-filled to a grade that allowed drainage away
from the area. No final soil clean-up levels were established for
this removal action since the excavation reached groundwater in
portions of the trench. Therefore a majority of the soil was
removed. Soil samples were taken in the remaining areas above the
water table at the base of the trench and contamination was found.
This remaining contamination was addressed in the Interim Action
Source Control Operable Unit (SCOU) Record of Decision (ROD).
Below is a list of contaminants that were found from a
representative sample of liquid collected from excavated drums on
the staging pad on April 17, 1991. The list below shows
contaminants that were above detection limits. The detection
limits for all contaminants were elevated due to sample
concentrations.
Benzene Chloroform Ethyl Benzene
Toluene Trichloroethene Methylene Chloride
Some of the other contaminants that were sampled for and found but
not quantified because of elevated detection limits include; vinyl
chloride, tetrachloroethene, 1,2-dichloroethane, and 1,1-
dichloroethene. Contaminants found within the drum trench are
contaminants that are present in monitoring wells at the Site.
The liquids from the excavated drums were separated, bulked, and
disposed of through either a fuels blending program or
incineration. The liquids used in the blending program were sent
was Solvent Resource Recovery facility in West Carrolton, Ohio and
incinerated liquids were processed at Aptus Environmental Services
in Coffeyville, Kansas. A majority of the soils were disposed of
in a hazardous waste cell unit at the Calumet Industrial Design
Landfill (CID) in Calumet City, IL. Solids remaining in the drums
were tested, bulked and accepted at a fuels blending facility in
April of 1992 for repackaging. The solids totaled approximately 15
cubic yards and were then sent to a facility in Texas for
incineration. The disposal procedures occurred from October 1991
through April 1992.
C. Remedial Investigation/Feasibility Study (RI/FSl
On September 17, 1987, WMWI signed an Administrative Order on
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Consent with U.S. EPA to conduct a Remedial
Investigation/Feasibility Study (RI/FS) for the site. The purpose
of the RI was to identify sources of contamination and to
characterize the contamination at the site. The RI was finalized
on November 4, 1992. The Final RI includes a Baseline Risk
Assessment which was conducted to characterize the current and
potential threat to public health and the environment at the site.
To focus and expedite clean-up of the site, the project was divided
into two operable units - the Source Control Operable Unit (SCOU)
and the Groundwater Operable Unit (GWOU) or Final Remedy. The SCOU
focused on removing and containing remaining contaminants in on-
site soils to minimize the further spread of contamination; the
GWOU focuses on cleaning up contamination in groundwater at the
site.
A Source Control Operable Unit FS was prepared in September 1991.
That FS provided a detailed analysis of alternatives evaluated for
the interim action SCOU. The SCOU remedy proceeded as an interim
remedial action even before the Baseline Risk Assessment and RI
were completed. The FS for the GWOU was prepared in March 1993.
The alternatives developed in this FS are presented in the
Description of Alternatives, Section VII. Together with the SCOU,
this GWOU constitutes the Final Remedy for the Site.
D. Remedial Design/Remedial Action
In December 1992 a Record of Decision was signed for the Source
Control Operable Unit (SCOU) action at the site. This action
includes the design and installation of a 2 foot clay cap over the
waste areas, expanding the current leachate and gas extraction
system over the entire site, constructing an In-situ Soil Vapor
Extraction (ISVE) system in the area of the drum removal and
groundwater monitoring.
On December 9, 1991, U.S. EPA issued a Unilateral Administrative
Order requiring 46 identified potentially .. responsible parties
(PRPs) to perform the SCOU remedy. Those PRPs included Carl Wauer
(the site owner), WMWI (the site operator for a period of time when
hazardous substances were disposed of) , and 44 generators of
hazardous substances disposed of at the site. The vast majority of
these parties complied with the order and implemented the SCOU
remedy.
The Remedial Design for this SCOU work was completed and approved
in October 1993 and work began that same month. The entire project
was completed by October 1994 with minor field modifications that
included the removal of an underground storage tank and
approximately fifteen buried drums. Prior to the construction of
the clay cap, several buildings from the Anamax Rendering facility,
which has been acquired by WMWI, were demolished with the debris
consolidated on site. Full-time operation of the dual extraction
wells for leachate and landfill gas began in November 1994.
Groundwater monitoring under the Interim Groundwater Monitoring
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Plan (IGMP) began in April 1994 and will continue until a long-term
monitoring plan is designed and approved as part of the Groundwater
Remedy described in this ROD.
III. COMMUNITY PARTICIPATION
The U.S. EPA released its Proposed Plan for the final remedy for
the Site in October 1994, and has made it available for public
review and comment. The Proposed Plan and supporting documents
have been made available at the information repositories at the
U.S. EPA Region V offices, the Muskego Public Library, and the
Muskego City Hall. U.S. EPA has been placing relevant information
in these repositories since 1987. Notice of the availability of
the Proposed Plan was included in advertisements in the Muskego
Sun. Hales Corners Hub, and Waukesha Freeman in September 1994.
Press releases were also sent to local media. Before reaching a
final decision on how the site contamination would be addressed for
this action, U.S. EPA held a public meeting on October 17, 1994 at
the Muskego City Hall. At this meeting, representatives of U.S.
EPA and WDNR answered questions about the proposed remedy and
accepted formal comments from the public on the Proposed Plan and
remedial alternatives. U.S EPA also accepted written comments
during the comment period, which originally ran from October 2, to
November 2, 1994. A request for extension of the comment period
was submitted on November 2nd and accepted. The 30 day extension
moved the end of the public comment period to December 2, 1994. A
response to all comments received during the public comment period
is contained in the Responsiveness Summary, which is attached to
this the ROD.
Other community relations activities were associated with the
Source Control Operable Unit (SCOU) Proposed Plan and the RI/FS.
The first comment period was held from August 28 to September 27,
1987 concerning the signing of the RI/FS consent order. Press
releases announcing this comment period were sent to local media.
A community relations plan was finalized in early 1988. A
"kickoff" meeting to discuss the initiation of the RI was held at
the Muskego City Hall on Aug. 25, 1988. Advertisements and press
releases were sent to local media. A fact sheet was developed and
sent to everyone on the U.S. EPA's mailing list.
In June 1991, a press release concerning U.S. EPA's drum removal
project was issued and a fact sheet was developed and sent to
everyone on the mailing list. This fact sheet served as a notice
of activities associated with the drum removal and as an overall
update on site activities.
On December 12, 1991, U.S. EPA held a public meeting for the SCOU
Proposed Plan at the Muskego City Hall. At this meeting,
representatives for U.S. EPA and WDNR answered questions about the
proposed remedy and accepted formal comments from the public. U.S
EPA also accepted written comments during the comment period, which
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ran from November 18, to December 18, 1991. The SCOU ROD contained
a response to all comments received during the public comment
period.
Fact Sheets describing actions at the Site were released in July
1993 and June 1994. These annual informational updates were sent
to community representatives, concerned citizens, and local media.
These Fact Sheets have served as the primary sources of information
for the community since the comment period for the SCOU ROD. The
objectives of these fact sheets were to provide information on the
SCOU construction activities, to describe progress towards the
Final Remedy, and to serve as a reminder to local residents of whom
they may contact to answer questions regarding the site.
IV. SCOPE OF GROUNDWATER REMEDIAL ACTION
The Groundwater Operable Unit (GWOU) is intended to be the final
response action for this site. The action will directly address
on-site groundwater contamination concerns and control the threat
to off-site wells by containing and remediating contaminated
groundwater. These concerns arise both from existing contamination
and from further contamination that may migrate from source areas
on-site.
As with many Superfund sites, the problems at the Muskego Sanitary
Landfill are complex. Early site characterization activities
conducted as part of the RI identified sources of contamination
that could be addressed before full characterization activities
were complete. Therefore, to accelerate the remediation of the
sources of contamination, U.S. EPA, in consultation with WDNR,
organized the work into two operable units (OUs).
The first operable unit, the Interim Action SCOU, addressed
contamination movement into the groundwater and soils from sources
within the Old, Southeast, and Non-Contiguous Fill Areas. These
areas pose a threat to human health and the environment because of
the risks from possible ingestion of, or dermal contact with,
contaminated soils located there or possible ingestion of, or
dermal contact with, contaminated groundwater at private residences
downgradient of the Site. Based on sampling by the U.S. EPA in
August 1991, there.were no current impacts of Volatile Organic
Compounds (VOCs) at private wells downgradient of the Site.
However, the threat of future impacts to private well exists since
downgradient monitoring wells have shown contamination.
The first purpose of the SCOU response was to prevent current or
future exposure to the contaminated soils and to reduce contaminant
migration into the groundwater that is a current source of drinking
water for local residents. The second purpose of this response was
to prevent current or future exposure to landfill gas containing
explosive and potentially toxic contaminants and to reduce the
migration of landfill gasses to adjacent soils and structures.
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The combination of this action along with the previous actions is
intended to address the entire site with respect to the current and
potential future threats to human health identified in the RI, FS,
and site Baseline Risk Assessment.
V. SITE CHARACTERISTICS
A. Geology and Hvdroqeology
The site is located in an area of thick glacial drift overlying
Niagara dolomite. The drift thickness varies from approximately
300 feet on the east edge of the site to 50 feet at a location-
about 2,000 feet south of the site. The site overlies a deep
valley in the bedrock that is part of the Troy Valley which trends
to the east with a steep bedrock slope rising to the south.
The valley in the bedrock beneath the site is filled with sediments
consisting of sand and gravel with a cover of glacial till. In
general, fine-grained material (till and lacustrine deposits) south
and east of the site extend to .depths of approximately 70 to 200
feet. Below the till is coarse material (outwash) which extends to
depths of about 200 to 300 feet below land surface.
At the northern portion of the site is the Upper New Berlin
Formation which is a till deposit forming an east-west tending
moraine. The New Berlin Formation contains two principal members,
a lower sand and gravel unit and an upper till unit. The western
portion of the site consists of the lower outwash sand and gravel
unit that extends southwest from the site toward the Fox River.
The upper unit is typically gravel, sand, loam till that averages
about 58 percent sand, 29 percent silt, and 13 percent clay.
The sand and gravel deposits are present east of Crowbar Road and
south of the landfill access road, beneath the western edge of the
site, and extend east to the boundary of the basal clay under the
Old Fill Area (Figure 2).
Above the New Berlin formation is the Oak Creek Formation which
consists of a much finer textured composition of fine-grained till,
lacustrine clay, silt, and sand. This formation on an average
consists of approximately an 85 percent clay-silt composition. The
western limit of the Oak Creek Formation is the Valparaiso Moraine
and ends within the Old Fill Area. . The western extent of the clay
till and other low permeability material is vertically and
horizontally irregular. As a result, its extent cannot be
accurately defined, nor can an edge of low permeability material of
constant thickness be mapped with an acceptable degree of
certainty. The approximate Basal Layer Boundary is outlined in
Figure 2.
The glacial sediments in the area are underlain by the Silurian-
aged Niagara dolomite, at depths between 250 to 350 feet below land
surface. The Niagara dolomite is sequentially underlain by
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Maquoketa shale, dolomites, sandstones, and igneous and metamorphic
rocks. The Maquoketa shale in the Site area is documented by
private well logs which indicate there is about 200 feet of shale
below the Niagara Dolomite.
The groundwater flow in the site area varies in direction due to
the complex geological features. The general groundwater flow for
the region is from the north to the south. Within unconsolidated
areas located at the northern and western edges of the site, the
groundwater moves in a southerly direction. However the geology by
the Southeast and Old Fill Areas consists of consolidated clay
layers. Therefore perched groundwater conditions exist in these
areas. Groundwater flows radially in all directions from these
areas. (Figure 3) Groundwater from the northern portion of the
site near the old rendering plant lagoons is split by a low
groundwater divide in the sand and gravel deposits. One flow path
moves generally along a Southeast route.that is directed beneath
the Non-Contiguous Fill Area, the Southeast Fill Area and the
Anamax plant. The other flow path moves generally along a southern
route that is directed under the Old Fill Area.
Similar to the groundwater flow, the water table in the site area
also varies due to complex geological features. Since the site is
located at the end of two glacial advancements, the Berlin and
Oakcreek formations, consolidated clay layers are intermixed with
unconsolidated sand and gravel. Since the permeability of these
soils varies so does the water table. Therefore the water table at
the site is from 20 to 40 feet deep. In areas where groundwater is
perched or leachate is held within the basal layer the water table
is 20 to 30 feet deep.
Presently, the main aquifer in the sand and gravel unit is used for
private water supply downgradient of the site in only two private
residences. Public water was provided to the Site area in 1986
along Janesvilie Road to the South and Hillendale Avenue to the
east. The municipal well system is located a few miles east of the
site and is not near, nor is it affected, by the site.
Hydraulic conductivity varies throughout the site depending on the
soil type. Within the clay till, the hydraulic conductivity ranges
from 1.6 x 10'6 centimeters per second (cm/s) to 5.1 x 10'* cm/a.
However, the hydraulic conductivity of the sand and gravel deposits
is much higher, ranging from 3.9 x 10'2 cm/s to 1.2 x 10'3 cm/s.
B. Nature and Extent of Contamination
The RI sampling of groundwater was conducted at monitoring wells
and private wells throughout the site. Since April 1994
groundwater monitoring has been conducted under the Interim
Groundwater Monitoring Plan (IGMP) which will continue until a long
term monitoring plan is implemented under this ROD. The IGMP
includes semi-annual sampling of volatiles, serai-volatiles and
inorganics. Quarterly sampling for indicator parameters is also
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performed tinder the IGMP. During the IGMP several monitoring wells
throughout the site were abandoned due to poor well construction
quality, SCOU remedial activities, or various factors. Since this
work was completed after this FS was drafted these wells are not
reflected as abandoned in the tables and figures for this ROD but
a description of the IGMP has been included as Attachment A.
Groundwater
Groundwater is the main pathway of concern for contaminant
migration at the site. As* mentioned above, there are two main
groundwater flow paths. The first one, known as the Southern flow
path, runs from the northern section of the site under the Old Fill
Area and continues to the south. The second or Southeast flow
path, also moves from the northern portion of the Site, but is
diverted to the southeast and flows beneath the Southeast Fill
Area, the Non-Contiguous Fill Area and Anamax property. In
addition, conditions exist where leachate accumulates in areas
above these flow paths in perched or elevated conditions (Figure
3) . A summary of the organic group results for all monitoring
wells at the site is listed in Table 1.
Southern Flow Path - The Southern Flow Path is potentially affected
by the former rendering plant lagoons, and the Old and Non-
Contiguous Fill Areas. Two rounds of groundwater sampling occurred
at 12 downgradient wells at seven different locations. A summary
of U.S. EPA MCL and WDNR NR 140 exceedances is provided in Table 2:
locations of the monitoring wells are shown in Figure 4.
Organic contamination located in the Southern Flow Path includes
BETX (benzene, ethylbenzene, toluene, xylene), chlorinated ethene,
and chlorinated ethane groups. Individual chemical concentrations
and well locations are listed below.
Constituent Concentration Well Location
Benzene 1 ug/L 135A
Toluene 3 ug/L 123B
Ethylbenzene 3 ug/L 123B
Xylene 1-13 ug/L 1 2 3 B , 9 6 P
Tetrachloroethene 1 ug/L 123B
Trichloroethene 1-3 ug/L 123B, 135B, 138A
1,2-Dichloroethene 1-8 ug/L 135A-B, 137A-B, 96
Chloroethane 2 ug/L 135A
1,2-Dichloroethane 2 ug/L 135A, 137A
1,1-Dichloroethane 1-5 ug/L 135A-B, 137A-B, 95P, 96
Semi-volatile compounds and pesticides/PCBs were not detected in
the Round I groundwater samples collected from the Southern Flow
Path. Therefore, Round 2 samples were not analyzed for these
parameters.
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Groundwater monitoring wells were also sampled for Target Analyte
List (TAL) metals and cyanide, and general groundwater quality
indicators. These analyses were used to assess chemical
concentration trends within the aquifer to aid in the determination
of groundwater flow patterns, and contaminant fate and migration.
There are seven TAL constituents that were detected in one or more
monitoring well, sample(s) along the Southern or Southeastern Flow
Paths at levels higher than those detected in the background wells
E80 and TW75. All of these seven were detected along the Southern
Flow Path at various wells. The constituents were as follows-:
* Arsenic * Lead * Zinc
* Barium * Manganese
* Chromium * Nickel
Southeast Flow Path - The Southeast Flow Path which diverts from
the Southern Flow Path in the northern area of the site, was
characterized using 11 monitoring wells at six locations. The.
organic compound sampling from these wells are summarized in Table
l; locations of the monitoring wells are shown in Ficrure 5.
There are four organic contaminant groups that were detected on-
site along the Southeast Flow Path. These groups are BETXs ,
chlorinated ethenes, chlorinated ethanes, and phthalates.
Individual concentrations and well locations are listed below. One
organic contaminant, vinyl chloride, was found off-site, at levels
in exceedance of Federal Maximum Contaminant Levels (MCLs) and
state NR 140 Enforcement Standards (ESs) as shown in Table 3. The
vinyl chloride contamination was found during groundwater
monitoring southeast of the Site at Well P64C.
Constituent Concentration Well Location
Benzene 1 ug/L 92A
Xylene 1 ug/L 92P
Trichloroethene 2-3 ug/L 92A
1,2-Dichloroethene 2-3 ug/L 92A
Vinyl Chloride 5-7 ug/L 64C
1,2-Dichloroethane 2 ug/L 92A
1,1-Dichloroethane 6-7 ug/L 92A
Additional organic" compounds detected in this area include 1,2-
dichloropropane from monitoring well E92A at a concentration of 2
ug/L (Rounds 1 and 2) ; and methylene chloride (a common/probable
laboratory contaminant) , at well TW62 at a concentration of 2 ug/L
(Round 1 only).
Phthalates were detected in one groundwater sample from this area
during Round 1 (E92-3 ug/L), and two samples from Round 2 (E94-4
ug/L, and TW62-3 ug/L). Constituent compounds detected were di-n-
octyl phthalate and bis (2-ethylhexyl)phthalate.
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As with the Southern Flow Path, pesticides/PCBs were not detected
in Round 1 groundwater samples collected from this area.
Therefore, Round 2 samples were not analyzed for these parameters.
There are five TAL constituents that were detected in one or more
monitoring well sample(s) along the Southeastern Flow Path at
levels higher than those detected in the background wells E80 and
TW75. These constituents are as follows:
* Arsenic * Zinc
* Barium * Manganese
* Nickel
Other areas - The Southern and Southeast Flow Paths described above
affect well locations primarily downgradient from the site as shown
in Figures 4 and 5.
Monitoring wells are also located in the Non-Contiguous Fill and
Anamax plant areas as well as along the northern extent of the Old
Fill Area (Figures 6 and 7) . The highest concentration of organic
contamination for the site was found at wells in the Non-Contiguous
Fill Area. Specifically, monitoring well E136, located in the Non-
Contiguous Fill Area, was contaminated with several VOCs at levels
in exceedance of MCLs and ESs as shown in Table 4.
Contaminant groups that were detected within the Non-Contiguous
Fill Area, Anamax plant and northern boundary areas include BETXs,
chlorinated ethenes, chlorinated ethanes, ketones, phenols, and
polycyclic aromatic hydrocarbons (PAHs). Some of the individual
concentrations and well locations are listed below.
Constituent Concentration Well Location
Benzene 1-21 ug/L 10 OA, 102A, 104
97P, TW74R, 87
Toluene 8-12,000 ug/L 102A, 136
Ethylbenzene 270-7,300 ug/L 102A, 136
Xylene 5-39,000 ug/L 102A, 136
Tetrachloroethene 3 ug/L 17R
Trichloroethene 1-7 ug/L 87, 100A, 104, TW74R
1,.2-Dichloroethene 1-12 ug/L 100A, 102A, 104
TW74R, 87
1,2-Dichloroethane 3-9 ug/L 102A, 87
l,l^Dichloroethane '3-8 ug/L 100A, 102A, 104
87, 97P
Chloroethane 8 ug/L 97P
2-Butanone 9-2,400 ug/L 136, TW74R
Two additional volatile compounds were detected in wells along the
northern boundary of the Old Fill Area. These included 1,2-
dichloropropane at 5 ug/L from well E17R, and tetrahydrofuran from
E48 at 41 ug/L. A summary of U.S. EPA MCL and WDNR NR 140
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exceedances in groundwater along the northern wells is provided in
Table 5.
Individual semi-volatile constituent compounds included phenol (870
ug/L), 4-methylphenol (2,100 ug/L), and naphthalene (360 ug/L) from
well E136; 4-methylphenol (5 ug/L) and benzoic acid (6 ug/L) from
well TW74R; and 2,4-dimethylphenol (2 ug/L) from well E102A. Along
the northern boundary wells, only di-n-butyl phthalate was detected
from well 90 at 2 ug/L.
Pesticides/PCBs were not detected in Round 1 groundwater samples
collected from these areas. Therefore, Round 2 samples were not
analyzed for these parameters.
There are TAL constituents that were found in one or more
monitoring well sample(s) in these areas at levels greater than
levels found in background wells E80 and TW75. These constituents
are as follows:
* Arsenic * Chromium * Lead * Manganese
Private Wells - Many of the private wells near the site have been
sampled several times during the history of operation at the site.
Sampling during pre-RI/FS activities by Warzyn, WMWI's contractor,
on May 3, 1991 and by U.S. EPA on August 28, 1991, showed that
nearby water supplies were not impacted, at that time, by site-
related contaminants. Locations of the nearby private wells are
shown in Figure 8. All private well sampling results are included
in Appendix K of the RI.
Soil
The results of the soil and sediment sampling were explained in
detail in the SCOU ROD, which focused on soil and sediment
contamination. The primary constituents of concern in soil are:
benzene, toluene, xylene, ketones, phenols and polynuclear aromatic
hydrocarbons (PAHs).
Air
The RI did not generate useable data on ambient air, leachate head
well and gas vent vapor emissions. The requirement for landfill
gas collection and treatment, NR 506.08 Wisconsin Administrative
Code (WAC), has been addressed by implementation of a landfill gas
management system as part of the SCOU remedy. This system should
control any releases to the air from the waste material and there
are no further expected sources of air contamination from the site.
Air monitoring and treatment may be required depending on the
installation of groundwater treatment systems. Air emissions
resulting from a groundwater treatment system would be regulated by
NR 445, Wis. Adm. Code. At this time treatment of air emissions
from a groundwater treatment system, such as an air stripper, is
not expected to be necessary.
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Surface Water
Topographic highs in the vicinity of the site consist of a large
end moraine north and northeast, and two topographic highs created
by the Stoneridge facility and the Southeast Fill Area. The
natural topographic high acts as a surface water divide. The
majority of the runoff from the site flows to the southeast to two
wetland areas and to an intermittent stream. Runoff from the
western portion of the Old Fill Area flows to Crowbar Road on the
west end of the site.
Surface water is not a significant contaminant migration pathway at
the site due to the lack of permanent surface water features and
the presence of newly placed cover soils, which will generally
prevent contact of surface-water runoff with refuse. Sampling of
surface water was not conducted during the RI.
VI. SUMMARY OF SITE RISKS
The Comprehensive Environmental Response Compensation and Liability
Act (CERCLA) , 42 U.S.C. §§ 9601 et seq.. requires that U.S. EPA
protect human health and the environment from current and potential
exposure to releases of hazardous substances at or from the site.
As part of the RI, a Baseline Risk Assessment is required in order
to assess the current and potential future risks by the Site. The
baseline risk assessment determines whether contamination at the
landfill could pose an unacceptable health risk or environmental
risk in the absence of any remedial action. Potential threats to
public health are estimated by making assumptions about the manner,
frequency and length of time a person could be exposed to site-
related contaminants.
This Baseline Risk Assessment was prepared in a manner consistent
with U.S. EPA policy, as expressed in "Role of the Baseline Risk
Assessment in Superfund Remedy Selection Decisions," dated April
22, 1991. The quantitative risk assessment examined contaminants
detected in groundwater, leachate, and soils during the field
investigation phase of the RI. These contaminants were evaluated
with respect to their carcinogenicity, toxicity, and possible
exposure pathways from and at the site.
A. Identification of Chemicals of Potential Concern
The purpose of selecting chemicals of potential concern for the
risk assessment is to identify those chemicals present at the site
most likely to be of concern to human health and the environment.
Since the Final Remedy addresses groundwater, the following is a
list of contaminants detected in soil and groundwater at and near
the site. The following codes are used to identify the various
groundwater well location areas around the site where contamination
was located.
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Non-contiguous Fill
Southeast Flow Path
Southern Flow Path
Northern Boundary
Organ!cs:
Benzene - NC,SE,SO,NB
2-Butanone - NC
Chloroform - NC
Di-n-butylphtalate - NB
1,2-Dichloroethane - NC,SE,SO,NB
1,2-Dichloropropane - SE,SO,NB
bis(2-Ethylhexyl)phthalate - SE
Ethylbenzene - NC,SO
Naphthalene - NC
Pyrene - SO
Tetrachloroethene - NB
Toluene - NC
Vinyl Chloride - SE
Area/Former Anamax Facility
NC
SE
SO
NB
Benzoic Acid - NC
Chloroethane - NC,SO,
Di-n-octyl Phthalate - SE
1,1-Dichloroethane - NC,SE,SO,NB
1,2 -Dichloroethene - NC, SE, SO, NB
2,4-Dimethylphenol - NC
Dichlorofluoromethane - NC,SE,SO
4-Methylphenol - NC
Phenol - NC
Pentachlorophenol - SO
Tetrahydrofuran - NB
Trichloroethene - NC,SE,SO,NB
Xylenes (total) - NC, SE, SO
Inorganics: %
Aluminum - NC
Barium - NC,SO,SE,NB
Calcium - NC,SE,SO,NB
Chromium - NC,SO
Copper - NC,SO
Lead - NC,SO,SE,NB
Manganese - NC,SO,SE,NB
Potassium - SE,SO
Selenium - SE,SO
Sulfate - SE
Vanadium - NC
Arsenic - NC,SE,SO,NB
Cadmium - NC
Chloride - NC,SE,SO,NB
Cobalt - NC,SE,SO,NB
Iron - NC,SE,SO,NB
Magnesium - NC
Nickel - NC,SE,SO,NB
Silver - NC,NB
Sodium - SE,SO,NB
Thallium - SO
Zinc - NC,SE,SO
Of the chemicals in groundwater, those which exceeded the Safe
Drinking Water Act or state NR 140 WAC groundwater standards are
shown in Tables 2, 3 and 4. This Table compares the maximum
groundwater concentrations in the immediate source areas with the
MCLs, state NR 140 Enforcement Standards (ESs) and Preventive
Action Limits (PALs) .
Based on toxicological studies, benzene and vinyl chloride are
classified as U.S. EPA Group A - human carcinogens; while
trichloroethene, tetrachloroethene and pentachlorophenol are
classified as Group B2 - probable human carcinogens. Typically,
exceedances of drinking water standards (such as the MCLs) may
justify the need for remedial action. The Baseline Risk Assessment
reinforces the existence of a potential threat to public health,
welfare or the environment. Actual or threatened releases of
hazardous substances from this site, if not addressed by
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implementing the response action selected in this ROD, may present
an imminent and substantial endangerment to public health, welfare,
or the environment.
B. Exposure Assessment
The objective of an exposure assessment is to estimate the type and
magnitude of exposures to constituents of potential concern that
are present or are emanating from the site. There are two
scenarios to consider for an exposure assessment. The first is a
current use scenario and the second is a reasonable future use
scenario. This assessment will be focused on groundwater since the
SCOU has already limited exposures through all other media. In
order to complete an exposure assessment the exposure pathways must
be identified. An exposure pathway must include the following four
elements; (1) a source and mechanism of chemical release to the
environment, (2) a transport media (e.g. groundwater), (3) an
exposure point, and finally, (4) an exposure route such as
ingestion or inhalation at the contact point. In summary, the
exposure assessment is a review of how contamination may come in
contact with living organisms via groundwater.
Groundwater Pathways - Current uae scenario
Site-related chemicals have been detected in the sand and gravel
aquifer in the immediate area of the source areas. The potential
exists for this contamination to move with groundwater flow toward
private residences. However, at this time there are no currently
active residential wells on or nearby the site. Two downgradient
private wells screened in the sand and gravel aquifer are available
for non-potable uses. These wells were included in the August 1991
sampling conducted by the U.S. EPA which did not detect any VOCs in
private water supplies. One of these wells has since been sampled
as part of the Interim Groundwater Monitoring Plan (IGMP) and also
has not shown any detections of VOCs. There is no indication that
these wells were impacted by site-related chemicals, and therefore,
groundwater was not evaluated under a current use scenario.
However, the IGMP did verify that contaminants are still present in
monitoring wells downgradient of the source areas.
Future use scenario
According to the National Contingency Plan (NCP) , a no-action
alternative must address changes of land use associated with the
site which may result in exposure and risk to the chemicals of
potential concern. • Table 6 (4.2 in Risk Assessment of RI)
summarizes the exposure pathway analysis for future site use
conditions. This table can also be found in Section 4 of the
Baseline Risk Assessment of the RI. Since the SCOU has been
completed the only direct exposure media of concern are
groundwater.
Under future-use conditions, the assumption was made that a
hypothetical well would be constructed on-site or immediately
downgradient from the site in either of the two primary flow paths
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and would be used for water consumption. Therefore, future
residents could be exposed via ingestion of site-related chemicals
from drinking water and inhalation of volatile chemicals while
showering. Dermal absorption is not being considered because it is
less significant than the other two groundwater exposure routes.
Cumulative risk is driven primarily by potential ingestion of
groundwater and inhalation of shower water. Therefore the addition
of the dermal absorption scenario would not impact the cumulative
risk. From these scenarios, assumptions can be made so as to
quantify the risk scenarios. These estimates and assumptions are
provided in the Toxicity Assessment section of the risk assessment.
C. Toxicity Assessment
The Toxicity Assessment explains contamination levels, risk levels
and potential carcinogenic effects for contaminants of concern.
Risk levels show the potential for increased cancer effects based
on a lifetime exposure of the contaminants known to cause cancer.
Based on U.S. EPA risk assessment guidance, exposures are
quantified by estimating the reasonable maximum exposure (RME)
associated with the pathway of concern. An acceptable risk range
for the U.S. EPA according to the NCP is 10*4 to 10'6. This means
a range of increased cancer frequency from one additional person
out of 10,000 to 1 out of 1,000,000 people. Risks from non-
carcinogenic health hazards are based on a Hazard Index value. The
Hazard Index value is calculated on the exposure amount compared to
a Reference Dosage. Reference Dosage guidelines are established by
U.S. EPA. Hazard Index values greater than 1 indicate there may be
potential health risks associated with exposure to the chemicals
evaluated.
Ingestion of Groundwater
Drinking water exposures for a hypothetical future resident located
on-site and downgradient from the site were evaluated. Chronic
daily intakes were calculated for residential drinking water
exposures using the RI monitoring data for the Non-Contiguous Fill
Area, Southeast Flow Path and Southern Flow Path data groupings.
The exposure parameters for this pathway are presented in Table 7
(Table 4-16 in BRA of RI) . Exposures were assumed to occur 350
days/year, with the residents living in the same location from
birth to age 30 out of their 70-year expected lifetime.
The resulting Chronic Daily Intake (CDI) levels for chemicals
exhibiting carcinogenic effects and chemicals exhibiting
noncarcinogenic effects due to ingestion of groundwater were
calculated. These values were then taken and used to estimate the
total future scenario risk presented in section D.
Inhalation While Showering
Inhalation exposures to volatile chemicals while showering with
groundwater were calculated for hypothetical future residents. The
exposure parameters for inhalation of volatiles from showering by
residents are presented in Table B (Table 4-20 in BRA of RI)) .
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These are standard parameters used by U.S. EPA to assess this
pathway. These parameters include an exposure time of 17 minutes,
a frequency of exposure of 350 days/year, an exposure duration of
30 years, and an expected lifetime of 70 years. The exposure point
concentrations were calculated using a shower model described in
Appendix B of the RI. The resulting risk from these calculations
is explained in the Risk Characterization section below.
D. Risk Characterization
The objective of this section of the assessment is to present and
evaluate the human health risks potentially associated with
ingestion of groundwater and inhalation of volatile organics while
showering. By taking the chronic daily intakes (GDI) and
inhalation exposure concentrations (lECs) and combining them with
the health effects criteria, a risk level can be calculated for the
site. The risk level of IxlO'6 represents an upper bound
probability of one in one million that an individual could contract
cancer due to exposure to the potential carcinogen under the
specified exposure conditions.
In reviewing a future risk scenario, the following conditions were
assumed in order to determine the risk.
1. A private well would be installed downgradient of the Site in
the Southeast Flow path.
2. Concentrations similar to the Vinyl Chloride levels found in
monitoring wells where contamination was found would be detected in
the private wells installed.
3. 1.6 liters of water would be consumed 350 days per year for 30
years.
4. The body weight of the individual drinking the water is 48
kilograms (106 pounds) and the average lifetime would be 70 years.
Using these assumptions in combination with site data, an
individual drinking groundwater under these conditions would have
a 1 in 10,000 (10~4) chance of obtaining cancer. This estimation
is for carcinogenic compounds only.
Potential risks for noncarcinogens are presented as the ratio of
the CDI to the reference dose (COI:RfD) for each chemical, or as
the ratio of the IEC to the reference dose concentration (IEC:RfC) .
The sum of the ratios of all chemicals under consideration is
called the hazard index. The hazard index is useful as a reference
point for gauging the potential effects of environmental exposures
to complex mixtures. In general, hazard indices which are less
than one are not likely to be associated with any health risks, and
are therefore less likely to be of regulatory concern than hazard
indices greater than one.
The summary of potential health risks associated with the site
under the future land use assumptions are provided in Table 9
(Table 5-17 BRA of RI or Table 33 of FS) . This table includes both
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carcinogenic and non-carcinogenic effects. The cumulative risk for
the Non-Contiguous Fill Area is 6 x 10'4 or six additional cancer
cases in ten thousand people. The cumulative risk for the
Southeast Flow Path is 1 x 1CT4 or one additional cancer case in ten
thousand people. The cumulative risk for the Southern Flow Path is
8 x 10'6 or eight additional cancer cases in one million people.
Southeast Flow Path
The risk associated with the Southeast Flow Path is predominantly
due to the presence of Vinyl Chloride. Vinyl Chloride is a known
carcinogen and therefore is estimated with a higher weight- for
causing cancer. Vinyl Chloride was found in one .well above MCLs
and ESs during both rounds of the RI. Results from the IGMP
indicate Vinyl Chloride was detected in two additional wells. The
highest detection of Vinyl Chloride is 7ug/l in this flowpath.
Therefore the risk associated with the Southeast Flow Path is
primarily based on potential groundwater ingestion in this area
over a prolonged time period.
Southern Flow Path
The upper bound lifetime excess cancer risk to a potential future
resident through ingestion of groundwater from the Southern Flow
Path wells is 6xlO'6. This value is primarily due to the presence
of 1,2-dichloroethane and 1,2-dichloropropane detected in
monitoring wells in this flow path. The hazard index for the
southern flow path exceeds one (5) which is entirely due to
thallium. Thallium was detected at 17ug/l. Exposure to thallium
can be associated with elevated enzyme levels in blood serum and
baldness.
Non-Contiguous Fill Area
The potential upper bound lifetime excess cancer risk to a future
resident through ingestion of groundwater from the Non-Contiguous
Fill Area wells is 6xlO'4. This value is predominantly due to the
presence of Arsenic in these wells. However, Benzene, 1,2-
Dichloroethane, and Trichloroethene each have an upper bound
lifetime excess cancer risk greater than 1x10'6 which is within the
range U.S. EPA considers for taking remedial actions. The hazard
index for the Non-Contiguous Fill Area is ten, which is well in
excess of the level (one) where health effects are expected. The
primary chemicals accounting for these results are 2-butanone,
ethylbenzene, naphthalene, arsenic, and manganese. These results
indicate that adverse noncarcinogenic effects could potentially
occur if on-site groundwater from the Non-Contiguous Fill Area is
ingested on a daily basis over many years.
The potential upper bound lifetime excess cancer risk to a future
resident through inhalation of volatiles while showering with
groundwater from the Non-Contiguous Fill Area is IxlO*5. This value
is primarily due to the presence of benzene and 1,2-dichloroethane.
Benzene was detected at concentrations ranging from 1 ug/L to 21
ug/1 in seven of 12 wells. Two detected concentrations of
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1,2-dichloroethane (out of 12 samples) were 4 and 9 ug/1. The
total hazard index exceeds one (9) . This value is primarily due to
the presence of xylenes, but also included 1,1-Dichloroethane,
Ethylbenzene and Toluene. Based on the potential exposure to
xylenes, adverse noncarcinogenic effects could potentially occur to
the central nervous system and respiratory tract if groundwater
from this well is used for showering on a daily basis over many
years.
E. Ecological Risk Assessment
The ecological risk assessment evaluates the potential impacts to
nonhuman receptors associated with possible exposures to the
chemicals identified in the human health assessment. This
assessment is similar to the human risk assessment in that it
identifies potential receptors, conducts an exposure and toxicity
assessment and evaluates the risk characterization. Details of
this process are provided in section 6 of Appendix A of the RI.
Below is a brief overview of this section.
Potential receptors evaluated for this assessment include plants,
birds, mammals, livestock, reptiles and amphibians. Since it is
not feasible nor practical to assess impacts to every species
potentially affected by exposure to chemicals of potential concern
it is appropriate to select "indicator" species. These indicator
species are representative of potential impacts in other species at
the site.
Conclusions of the ecological assessment show that it is unlikely
any adverse affects to aquatic invertebrates, birds and mammalsr
livestock, and sensitive species have occurred. The most important
potential exposure pathway for ecological receptors at this site is
associated with chemicals in sediments in the drainage way and the
wetland area. There is some potential for adverse impacts to
sensitive aquatic invertebrates from exposure to 4-methylphenol in
drainage way sediments and phenol in wetland sediments. However,
these chemicals have not been widely detected. Overall, absolute
conclusions regarding the potential environmental impacts are
difficult to make due to uncertainties surrounding the estimates of
toxicity and exposure. Given the uncertainties and the relatively
lp_w levels of contaminants of concern in the drainage way and
wetlands, it is unlikely any major adverse affects to the
environment have occurred at the site. Based on completion of the
SCQU remedy it is also very unlikely that any future adverse
affects would occur.
F. Uncertainties
The estimates of risk for the site have several associated
uncertainties. The primary sources of uncertainty are the
following:
* Environmental sampling and analysis, and selection of
chemicals
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* Exposure parameter estimation
* Toxicological data
The risk assessment for this site should not be construed as
presenting an absolute estimate of risk to persons potentially
exposed to chemicals from the site. Rather, it is a conservative
analysis intended to indicate the potential for adverse impacts to
occur. Details regarding uncertainties and assumptions used in the
risk assessment can be obtained in Section 7.0 of the Baseline Risk
Assessment (Appendix A of the RI).
VIZ. DESCRIPTION OF ALTERNATIVES
A. Remedial Action Objectives
Upon completion of the source control - operable unit remedial
action, certain objectives that were developed during the RI have
been addressed. These objectives include reducing leachate from
entering the groundwater and reducing migration of contaminants
from the source areas. These actions will contribute to attainment
of the long-term goals of protecting human health and the
environment and meeting applicable or relevant and appropriate
requirements. (ARARs). The main objective of this groundwater
operable unit remedial action is to reduce and contain
concentrations of contaminants in groundwater at the site thereby
minimizing its migration. The clean-up goals for this site will be
to meet Federal Maximum Contaminant Levels (MCLs), and state NR 140
Enforcement Standards (ESs) and Chapter NR 140 Preventive Action
Limits (PALs) . Since NR 140 PALs are the most stringent standards,
these are the primary goals on which this action is based.
Consistent with Section 300.430(a)(1)(iii) (F), U.S. EPA expects to
return useable groundwater at the Site to beneficial use wherever
practicable, with a timeframe that is reasonable given particular
circumstances of the Site.
Since the SCOU remedy for this site has already been implemented,
the Final Remedy specifically addresses the reduction of
contaminant concentrations in groundwater at the site. A phased
approach has been taken on this project in order to monitor
progress toward clean-up objectives and to assess the additional
impact of the SCOU remedy on groundwater contamination. Monitoring
the progress achieved by the SCOU in effectuating clean-up goals,
and documenting how such progress is measured, will also be
objectives of this remedy.
B. Development of Alternatives
Alternatives developed in the FS for the Final Remedy considered
all prior remedial actions implemented at this site. These actions
include previous drum removals and work conducted under the SCOU.
Consideration of these actions reflects a phased approach to
project management that has been consistently used at this site.
This phased approach allows the project to progress while
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simultaneously monitoring the effects of previous work. This same
approach will be used to document the progress and attainment of
groundwater clean-up goals.
The remedial alternatives were assembled from applicable remedial
technology options. A wide range of technologies and remedial
options were reduced by evaluating them with respect to technical
implementability. The alternatives surviving the initial screening
were evaluated and compared with respect to the nine criteria
required by the NCP. In addition to the remedial action
alternatives, the NCP requires that a no-action alternative also be
considered for the site. The no-action alternative serves
primarily as a point of comparison for other alternatives.
The strategy used to develop alternatives was to first provide
general response actions typical for groundwater remediation.
These actions include:
o Institutional Controls
o Groundwater Monitoring
o Groundwater Controls
o Groundwater Treatment
o Groundwater Discharge
These general response actions describe a variety of institutional
controls and remedial actions intended to satisfy the groundwater
objectives. These general actions were screened to evaluate which
were implementable prior to comparison to the NCP criteria.
Institutional Controls
Institutional controls include deed restrictions and land use
planning. The purpose of these controls is to restrict development
and/or installation of water supply wells in the vicinity of
impacted groundwater. Deed restrictions have been placed on the
property parcels where the fill areas are located. These parcels
are owned by the Respondents (WMWI and Mr. Carl Wauer) and the
restrictions placed in accordance with the SCOU remedy. Also, .
according to State regulations, the installation of a water supply
well in a known contaminated aquifer or within 1,200 feet of the
nearest edge of an abandoned landfill is prohibited, unless a
variance is granted by the WDNR. However, deed restrictions can
only be implemented by a property owner thereby limiting the
effectiveness of this requirement. Since deed restrictions are
already in place for the required properties there is no need for
any additional restrictions for this remedy. Enforcement of the
water supply well prohibition is dependent on the property owner or
well driller contacting the WDNR prior to well installation. Also,
the WDNR can grant variances from the prohibition, so the
prohibition is not absolute, even if the WDNR is contacted.
Therefore, the effectiveness of institutional controls relating to
water supply well prohibition is dependant upon the site owner or
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contractor contacting the WDNR, and is not absolute, even if the
WDNR is contacted.
Groundwater Monitoring
Currently groundwater monitoring is ongoing from the SCOU under the
Interim Groundwater Monitoring Plan. The goals of a groundwater
monitoring program, without additional groundwater extraction, are
to monitor changes in groundwater contaminant concentrations within
the identified flowpaths, and evaluate the effectiveness of the
SCOU activities. In addition to these goals, a long-term
monitoring program that includes groundwater extraction' and
treatment would include:
o Provide data to assess the extraction well capture zone,
o Evaluate the effects on the groundwater from discharge to an
infiltration basin,
o Evaluate trends in groundwater contamination and the impact of
any activities associated with this remedy.
Groundwater Controls
Groundwater controls are active means by which contamination within
the groundwater would be contained, reduced and/or eliminated.
Certain controls were evaluated but disregarded due to
implementability considerations. These include: 1) underground
barriers to reduce groundwater migration from the site; 2)
groundwater extraction trenches; and 3) groundwater control by
injection for enhancement of biological degradation. Geological
features at this site prevent underground barriers and groundwater
extraction trenches from reducing migration away from the site. The
New Berlin and Oak Creek Formations intersect in the area of the
site thereby creating a complicated pattern of clay and sand seams.
This pattern creates an intricate groundwater flow configuration
around the site. Therefore a single barrier or extraction system
such as a wall would not adequately impact multiple flow paths.
Biological degradation may not be effective because in-situ
bioremediation is not appropriate for large quantities of water
containing generally low concentrations of chlorinated aliphatic
hydrocarbons.
Groundwater controls that were retained for evaluation include: 1)
groundwater extraction wells; and 2) groundwater extraction wells
with injection of uncontaminated water through an infiltration
basin or trench. These controls were retained due to their
potential effectiveness at reducing contaminated groundwater and
the implementability of these specific actions.
Groundwater Treatment
Groundwater treatment was separated into inorganic and organic
treatment technologies. For the purpose of technology screening,
the discharge limits for extracted .groundwater are evaluated
relative to Chapter NR 140 PALs. Technologies related to treatment
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of inorganic parameters include precipitation, reverse osmosis, ion
exchange, and reduction.
• Technologies related to the treatment of organics in groundwater
include biological treatment, oxidation, photolysis, air and steam
stripping, spray evaporation, carbon adsorption, and thermal
destruction. Due to low concentrations of organic contaminants
biological treatment, photolysis, air and steam stripping, and
thermal destruction would not be the most effective technologies
comparatively and therefore were not retained.
Groundwater Discharge
Discharge of treated water to surface or groundwater, or discharge
of untreated 'or pretreated water to a Publicly Owned Treatment
Works (POTW) can provide a means of disposal for the extracted
groundwater. Surface water discharge areas that were considered
included the Fox River, approximately 1 mile west of the site, or
wetlands southeast of the site. Groundwater reinjection was not
retained due to the possibility of raising the water table near the
Stoneridge Facility and the source areas. However, groundwater
infiltration was retained since the impact on elevating the water
table would be less than direct reinjection. Discharge to a
wetland or groundwater infiltration must meet Best Available
Technology (BAT) requirements under ch. NR 220, Wis. Adm. Code, in
the effluent and NR 140 requirements in the groundwater below the
discharge area. Discharge to a wetland is similar .to an
infiltration basin but is more ecologically sensitive and would
require more stringent monitoring. Therefore, discharge to
wetlands was not retained. Discharge standards to a surface water
body such as the Fox River would not require similarly stringent
standards. Therefore, surface water discharge to the Fox River and
infiltration basin discharge locations were retained for
consideration for treated water. POTW discharge was retained for
non-treated extracted water.
C. Alternatives
Alternative 1 - No Action
Under Alternative 1 no additional corrective action would be taken
at- the site to address groundwater contamination. The removal of
leachate from the Southeast Fill Area, Old Fill Area, and Non-
Contiguous Fill Area would continue utilizing the current method of
pumping leachate from the existing collection system directly to
the sanitary sewer. The gas collection and flaring would also
continue as described in the SCOU. The newly constructed landfill
cap would minimize infiltration of rain water through waste. In
situ vapor extraction would continue in portions of the Non-
Contiguous Fill Area. Finally, deed restrictions that restrict
potential well installation on-site or nearby would continue.
Under a no-action scenario, contamination in the groundwater would
not be directly addressed. This would result in continued off-site
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migration of existing contaminants in the groundwater. Also,
contaminants would potentially move into groundwater from the
source areas. In particular, leachate extraction wells were not
installed in the Non-Contiguous Fill area because leachate head
levels in the area were not high enough to allow extraction to be
practicable.
A no-action remedy would allow the site to remain as it exists
today. Therefore, contamination within the aquifer would be
addressed primarily through attenuation and dispersion without
active restoration. There would be no capital or operational costs
associated with this alternative, beyond those associated with the
SCOU.
Alternative 2 - Long-Term Performance Monitoring
The Long-Tertn Performance Monitoring Alternative involves
monitoring of groundwater quality over time to evaluate the
effectiveness and performance of the previous activities performed
at the site. No groundwater remedial action would be taken as a
result of this alternative. The groundwater monitoring program
would incorporate the Interim Groundwater Monitoring Plan (IGMP)
and is assumed to include the installation of additional wells
during the remedial action. The actual number of sampling
locations, the sampling frequency, and the parameter list, would be
determined during the Remedial Design.
The. Long-term monitoring program would provide information on
groundwater conditions throughout the site. This alternative would
not provide additional protective measures nor directly address
groundwater standard exceedances. The capital cost for this
alternative would be $145,000 with Operation & Maintenance costs at
$161,000 per annum for an estimated 30 years resulting in a Net
Present Value of $2,620,000.
Alternative 3 - .Non-Contiguous Fill Area Groundwater Extraction and
Treatment (The Selected Remedy)
The purpose of this alternative is to directly address, through
groundwater extraction and treatment, the groundwater contamination
identified primarily in the vicinity of the Non-Contiguous Pill
Area. By reducing contaminant input to the Southern and
Southeastern Flow Paths from the Non-Contiguous Fill Area, which is
where the highest concentrations of contaminants were found on-
site, health risks from groundwater downgradient of the Fill areas
would be reduced and clean-up standards would be expected to be
reached over time through reduction of contamination in the
groundwater pathways and through natural means.
Manor components of Remedial Alternative
The major features of this alternative include a system which pumps
and treats contaminated groundwater near the Non-Contiguous Fill
Area, starting at a rate of approximately 50 gallons per minute
(gpm), with a discharge to an on-site infiltration basin.
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Treatment for VOCs and inorganics would include air stripping, an
acid wash of the air stripper, when necessary, with possible
inclusion of chemical precipitation. If necessary, carbon
treatment would be installed to comply with air emission standards
(NR 445, Wis. Adm. Code). Transportation of treatment residuals
would be to an approved facility. The treated water may initially
be discharged, on a short-term basis, to the local POTW until
treatment systems -are appropriately designed. Long-term
groundwater monitoring would be conducted both in the vicinity of
the Non-contiguous Fill Area and in the South and Southeast flow
paths to evaluate effectiveness and determine if contingency
measures are necessary to achieve groundwater clean-up goals (NR
140, Wis. Adm. Code) in all of these areas.
Alternative 3 would be implemented in a phased approach in order to
gather the necessary data to determine the progress towards, and
achievement of, clean-up objectives. This approach is consistent
with the approach to the overall site and parallels U.S. EPA
guidance for "Evaluating the Technical Impracticability of Ground-
Water Restoration", September 1993. The implementation of a
limited pump and treat system in the Non-Contiguous Fill Area would
occur in conjunction with a comprehensive pilot scale test. The
purpose of this test would be to determine aquifer characteristics
and evaluate discharge and treatment options.
Another goal for this alternative will be to continue updating the
estimate of the time frame needed to reach clean-up objectives.
Currently, it is difficult to assess the impact of the SCOU on
helping achieve groundwater clean-up. This will be facilitated
through continued, long-term performance monitoring at the site.
The Performance Evaluation Report would include a section that
evaluates remedial action performance data from the site and the
progress toward achieving clean-up objectives. This section would
be updated on at least a 5 year periodic basis and will include
recommendations on implementing additional remedial actions, or
improvements to the operation of the existing environmental
controls.
This alternative currently contemplates the installation of four
extraction wells downgradient of the North and South Refuse
Trenches and the L-Shaped Fill Area. The actual number and
location of extraction wells and extraction flow rates will be
determined after pilot-scale testing of the system. The total
estimated extracted flow rate is now assumed to be 50 gallons per
minute. This rate may be adjusted, depending on the results of the
pilot testing. A header pipe system would connect these wells to
a treatment system. Parameters anticipated to exceed discharge
standards include some VOCs, iron, manganese, and possibly arsenic.
Appropriate treatment of extracted groundwater is air stripping for
VOC treatment. The air stripper would be sized to reduce VOC
concentrations to prescribed effluent limits. If necessary,
further treatment would be added to meet applicable air emissions
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limits. Potential clogging of the treatment system caused by iron
and manganese precipitates would be a maintenance concern and could
be treated by periodic acid rinses of the unit, instead of
pretreating the influent using chemical precipitation. However, if
inorganic contaminant concentrations continue to exceed clean-up
standards, then precipitation or other inorganic treatment
technology, such as ion exchange, would be evaluated. The costs
for this alternative assume chemical precipitation will be
included.
Off-site discharge to a POTW, such as Milwaukee Metropolitan
Sewerage District (MMSD), may be appropriate until extracted
groundwater is characterized and confirmation is obtained that it
can be treated to levels adequate to permit discharge to an
infiltration basin. The cost for this alternative assumes
discharge during the first year of groundwater extraction would be
directly to MMSD. On-site treatment using air stripping would
begin the second year of groundwater extraction.
Discharge to an infiltration basin would meet ch. 'NR 220, Wis. Adm.
Code, WPDES Best Available Technology (BAT) requirements, at the
point of discharge and ch. NR 140, Wis. Adm. Code, PALs for all
contaminants in the groundwater at a point directly below the
discharge zone. To the extent it is subsequently determined that
it is not technically or economically feasible to achieve PALs, NR
140.28 provides substantive standards for granting exemptions from
the requirement to achieve PALs. Such exemption levels may not be
higher than the ESs.
Alternative 3 is planned to capture existing groundwater
contaminants and prevent additional migration of contaminants from
this source through contaminant removal and containment. The
Southern and Southeast Flow Paths would both be affected by this
action. The impact of this action in combination with the SCOU
cannot be precisely determined at this time. One of the goals of
this action will be to measure the effectiveness of this action
coupled with the SCOU remedy to determine progress towards
achieving clean-up goals.
The capital cost for this alternative is estimated to be $1.2
million. The operation and maintenance costs have a total present
value of approximately $6.2 million over a thirty year period.
Therefore the total Present Value Cost for this alternative is $7.4
million.
Alternative 4: Non-Contiguous Fill Area and Perimeter Groundwater
Extraction and Treatment
Alternative 4 contains 3 options. The options are based on the two
groundwater flow paths known as the Southern and Southeast Flow
Paths. Alternative 4A addresses contamination in the Southeast
Flow Path through groundwater extraction and treatment.
Alternative 46 addresses contamination in the Southern Flow Path
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through the same means. Alternative 4 combines 4A and 4B to
address all downgradient groundwater flow. All of the options also
include pumping and treating contaminated groundwater from the Non-
Contiguous Fill Area as provided in Alternative 3. The purposes of
this alternative are: 1) to directly address groundwater
contamination within the Southern and Southeast Flow Paths through
hydraulic containment and groundwater extraction; 2) to reduce
related risk in this groundwater to acceptable levels and; 3) to
reduce groundwater contamination in the vicinity of the Non-
Contiguous Fill Area.
Manor Elements of Alternative
The major elements of these alternatives include: groundwater
monitoring, extraction of contaminated groundwater, treatment and
discharge. This alternative has been divided into options that
address the Southern and Southeast groundwater flows both
separately and combined. The extracted groundwater generated under
Alternative 4, would exceed the capacity of the infiltration basin,
which is limited to an estimated 100-200 gpm. The same is true for
Alternatives 4A and 4B.
Similar to Alternative 3, this alternative would have the goal of
meeting U.S. EPA's.Groundwater Protection Strategy. In addition,
the groundwater monitoring data may be used to suggest adjustments
to the system to achieve clean-up standards.
Alternative 4A (Southeast Plow Path)
Alternative 4A assumes that 6 extraction wells averaging 100 feet
deep (3 wells at 70 feet deep, 3 wells at 130 feet deep) would be
installed. The total extracted flow rate for the southeast
perimeter extraction system is assumed to be 60 gpm. The actual
number of extraction wells and flow rate needed to accomplish the
purposes of this alternative would be determined during the
Remedial Design. Similar to Alternative 3, treatment for VOCs and
inorganics would include air stripping, acid washing of the air
stripper, when necessary, and possible inclusion of chemical
precipitation or ion exchange. Potential clogging of the treatment
system (air stripping tower) caused by iron and manganese is a
maintenance concern and would be treated periodically by acid
rinsing the unit. If necessary, carbon treatment would be
installed to comply with air emission standards (NR 445, Wis. Adm.
Code) and transportation of residuals to an approved facility. The
discharge of treated water would be to an on-site infiltration
basin and/or to the Fox River. This decision would be dependent on
information obtained during the Remedial Design regarding capacity
constraints of the infiltration basin and impacts on the
groundwater table. Any discharge to the Fox River would likely
require a ROD Amendment and public comment.
The .capital cost for this alternative is estimated to be $3.026
million. The operation and maintenance costs have a total present
value of approximately $842,000 over a thirty year period.
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Therefore the total Present Value Cost for this alternative is
$14.9 million.
Alternative 4B: (Southern Flow Path)
Alternative 4B specifically addresses contamination in the Southern
Flow Path through groundwater extraction and treatment. The
extraction system is assumed to include 5 extraction wells
averaging 160 ft. deep. The total extracted flow for the south
perimeter extraction system is assumed to be 125 gpm. This
combined with the flow rate from the Non-Contiguous Pill Area would
total 175 gpm. The FS (Appendix G) provides calculations
indicating that the proposed basin size is large enough to handle
the combined flow volume of 235 gpm. However, these calculations
do not take into account the reduction in permeability due to
sediment build-up and potential icing during the winter, affects on
raising the groundwater table, and current capacity of the basin
for stormwater and run-off from other local features. Therefore an
appropriate range for discharge is between 100 and 200 gpm.
Discharge to a second point may be necessary. Any discharge to the
Fox River would likely require a ROD Amendment and public comment.
The capital cost for this alternative is estimated to.be $3.207
million. The operation and maintenance costs have a total present
value of approximately $896,000 over a thirty year period.
Therefore the total Present Value Cost for this alternative is
$15.8 million.
Alternative 4: (Southeast and Southern Flow Paths)
Alternative 4 is a combination of Alternatives 4A and 4B. The
total extracted flow for this perimeter extraction system in
combination with the Non-Contiguous Fill Area is assumed to be 245
gpm. This extraction system would most likely require discharge to
the Fox River due to capacity constraints associated with the
infiltration basin. Discharges of extracted groundwater to the
river are subject to the Wisconsin Pollutant Discharge Elimination
System (WPDES) program. Any discharge to the Fox River would
likely require a ROD Amendment and public comment.
Potential discharge to the MMSD may be feasible for the low volume,
more highly contaminated water collected at the start of extraction
from the Non-Contiguous Fill Area. Any discharge to MMSD would
have to meet MMSD pretreatment and volume requirements. The actual
number of wells, flow rate, treatment system, and discharge system
would be determined during the Remedial Design phase.
Discharge to an infiltration basin would meet WPDES Best Available
Technology (BAT) requirements (214.12). at the point of discharge
and ch. NR 140, Wis. Adm. Code, PALs for all contaminants in the
groundwater at a point directly below the discharge zone. To the
extent it is subsequently determined that it is not technically or
economically feasible to achieve PALs, NR 140.28 provides
substantive standards for granting exemptions from the requirement
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to achieve PALs. Such exemption levels may not be higher than the
ESs.
The capital cost for this alternative is estimated to be $3.464
million. The operation and maintenance costs have a total present
value of approximately $950,000 over a thirty year period.
Therefore the total Present Value Cost for this alternative is
$16.7 million.
VIZI. SUMMARY OF COMPARATIVE ANALYSIS OP ALTERNATIVES
A. Introduction
U.S. EPA has established nine criteria that balance health,
technical, and cost considerations to determine the most
appropriate alternative. The criteria analyze the selected remedy
so that the remedy is protective of human health and the
environment, attains ARARs, is cost effective, and utilizes
permanent solutions and treatment technologies to the maximum
extent practicable. The remedial alternatives developed in the FS
have been evaluated and compared using these nine criteria which
are set forth in the NCP at 40 CFR Part 300.430 (e) (9) (iii) . These
nine criteria are summarized as follows:
OVERALL PROTECTION OF PUBLIC HEALTH AND THE ENVIRONMENT addresses
whether a remedy provides adequate protection of human health and
the environment and describes how risks posed through each exposure
pathway are eliminated, reduced, or controlled through treatment,
engineering controls, or institutional controls.
COMPLIANCE WITH APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS
(ARARs) addresses whether a remedy will meet all other Federal and
State environmental statutes and regulations and/or provides
grounds for invoking a waiver.
LONG-TERM EFFECTIVENESS AND PERMANENCE refers to the ability of a
remedy to maintain reliable protection of human health and the
environment over time, once clean-up standards have been met.
REDUCTION OF CONTAMINANT TOXICITY, MOBILITY, OR VOLUME through
treatment addresses the anticipated performance of the treatment
technologies a remedy may employ.
SHORT-TERM EFFECTIVENESS addresses the period of time needed to
achieve protection, and any adverse impacts on human health and the
environment that may be posed during the construction and
implementation period, until clean-up standards are achieved.
IMPLEMENTABILITY addresses the technical and administrative
feasibility of a remedy, including the availability of materials
and services needed to implement a particular option.
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COST includes estimated initial capital, operation and maintenance
(O&M) costs, and net present worth costs.
STATE ACCEPTANCE indicates whether, based on its review of the
RI/FS and Proposed Plan, the State concurs with, opposes, or has no
comment on the preferred alternative at the present time.
COMMUNITY ACCEPTANCE is based on comments received from the public
during the public comment period. These comments are assessed in
the responsiveness summary attached to this ROD.
B. Remedial Alternatives for Groundwater Remediation
The following briefly describes how the selected alternative for
groundwater remediation compares to other alternatives using the
nine criteria.
1. Threshold Criteria
The two most important criteria are statutory requirements that
must be satisfied by any alternative in order for it to be eligible
for selection. These two criteria are discussed below.
a. OVERALL PROTECTION OF HUMAN HEALTH AND THE ENVIRONMENT
This final remedy addresses groundwater, therefore the discussion
of protection of human health and the environment pertains
specifically to the groundwater media. The SCOU has addressed risk
from direct contact and air media scenarios. According to the
Baseline Risk Assessment within the RI, the cancer risk under
current land use conditions is within acceptable U.S. EPA ranges.
However, the future risk scenario indicates risk to potential
future groundwater drinking wells both on the site and
downgradient. Therefore protection of human health and the
environment is addressed from a potential future use scenario as
opposed to a current use scenario.
Alternatives 1 and 2 are not protective of human health and the
environment due to the continued movement of groundwater
contamination and potential human exposure via future private
wells.
Alternative 3 would provide appropriate protection since it
addresses contamination in the groundwater in the vicinity of the
Non-Contiguous Fill Area. The extraction system is anticipated to
capture existing groundwater and prevent additional migration of
contaminants. The Southern and Southeast Flow Paths would be
affected by remedial activities proposed for the Non-Contiguous
Fill Area, because the Non-Contiguous Fill Area is upgradient of
both Flow Paths. Alternative 3 does not directly address, through
groundwater extraction and treatment, contamination in exceedance
of groundwater standards beyond the Non-Contiguous Fill Area.
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However, contamination and potential risk in groundwater use
scenarios are greater in the Non-Contiguous Fill Area. Therefore
reduction of contamination in groundwater in this area coupled with
the SCOU activities are expected to lower groundwater contaminant
levels and therefore reduce associated potential risk levels. If
subsequent monitoring shows that the contaminant levels are not
being reduced adequately, this alternative allows for additional
remedial actions, including actions that may be similar to those
described in Alternative 4, to be implemented in a phased manner.
The way in which additional extraction and treatment may be phased
in is discussed in detail in the description of the selected remedy
and the compliance with ARARs criteria, below.
Alternative 4 would also provide protection by controlling
groundwater flow to a greater extent than any other alternative.
This Alternative includes groundwater extraction to capture
existing contaminants and prevent additional migration of
contaminants associated with the Non-Contiguous Fill Area,
Southeast Flow Path (Alternative 4A) and Southern Flow Path
(Alternative 4B) . At this time it is difficult to measure the
difference in the effect on groundwater contamination that
Alternative 4 would provide over Alternative 3. Since the Non-
Contiguous Fill Area has higher contaminant concentrations than the
Southern and Southeast Flow Paths the additional reduction of
contamination produced by extraction in these areas is unknown.
However, Alternative 4 provides the only method for immediate
direct extraction of contamination from all sources.
Protectiveness of human health and the environment for all
alternatives are based on the Baseline Risk Assessment (BRA) . The
BRA evaluates risk under two scenarios; current land use conditions
and potential future land use. Currently there are no private
residences using the groundwater aquifer since a public water
supply has been constructed. Therefore the current risk scenario
is negligible. For all alternatives, the contaminated areas of the
aquifer would remain unusable during the period of restoration.
The alternatives are enhanced in their effectiveness in protecting
public health by the implementation of the Source-Control Operable
Unit remedial components.
b. COMPLIANCE WITH APPLICABLE OR RELEVANT AND APPROPRIATE
REQUIREMENTS (ARARs)
Alternatives 1 & 2 do not include groundwater extraction and
treatment to directly address the identified State and Federal
groundwater exceedances. These alternatives rely upon the SCOU
remedial components to reduce contaminant (leachate) loading into
the groundwater, and periodic monitoring to provide information on
changing conditions at the site. While the SCOU activities will
enhance groundwater clean-up through reducing contaminant loading,
it will not address any current contamination within the aquifer.
Alternatives 1 & 2 would rely on attenuation and dispersion as the
means to achieve groundwater standards. U.S. EPA does not believe
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that these methods would be sufficient to meet the stated
groundwater clean-up standards. Sections NR 140.24(2) and NR
140.26(2), Wis. Adm. Code, outline the response objectives that
apply to this site. These sections require that contaminated
groundwater be restored where technically and economically
feasible, to achieve PALs. U.S. EPA does not believe Alternatives
1 & 2 would effectively restore groundwater within an appropriate
timeframe. Active remediation of the groundwater is necessary at
this site to achieve groundwater clean-up standards. Alternatives
1 & 2, if they could achieve standards over time (it is not known
at this time if they would) , would take many more years to achieve
the standards than Alternatives 3 or 4. Therefore it is likely
that Alternatives 1 & 2 would not comply with ARARs.
Alternative 3 directly addresses groundwater contamination through
extraction and treatment of the main area" of contamination •» the
Non-Contiguous Fill Area. The groundwater extraction and treatment
in Alternative 3 addresses the most highly contaminated groundwater
on site, which is upgradient of the Southeast and Southern Flow
Paths containing lower levels of contamination. Alternative 3
relies upon natural attenuation to reduce existing groundwater
contamination in those portions of the aquifer not addressed by
groundwater extraction wells. Based on data from the RI, U.S. EPA
believes that Alternative 3 would be more effective in addressing
contamination in the Southeast Flow Path as compared to the
Southern Flow Path. It is expected that the concentration of the
main contaminant in the Southeast Flow Path, Vinyl Chloride, would
be reduced to comply with groundwater standards through this
action. Moreover, a phased approach to Alternative 3 allows for
the implementation of additional remedial actions, including the
expansion of the scope and zone of influence of the groundwater
pump and treat component if it is shown, through long-term
groundwater monitoring, that groundwater ARARs are not being or
will not be achieved. For example, if monitoring wells show, after
a sufficient number of monitoring events, that state and federal
groundwater standards are consistently met, the system could be
turned off, in whole or part. If groundwater standards are not
obtained, but a decreasing trend is shown, then the system would
continue to be operated with continued monitoring. If contaminant
concentrations stay at the same level or are increasing, then
additional actions -may be taken. These additional actions could
include, but are not limited to: adjustments to the source control
measures such as leachate extraction, alternate pumping or pulse
pumping at current groundwater extraction wells, or installation of
additional groundwater extraction wells in the areas addressed by
Alternative 4. This final option may require an Explanation of
Significant Difference or ROD Amendment if modifications have
significant technical or cost implications. Determination of
adequate progress towards clean-up goals will be measured
periodically after system start up.^ The first evaluation would
occur within 5 years after the implementation of the SCOU actions.
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Alternative 4 would also directly address groundwater contamination
through extraction and treatment in the Non-Contiguous Fill Area,
the Southeast Flow Path (4A), and the Southern Flow Path(4B) . The
groundwater extraction and treatment in Alternative 4 addresses the
most highly contaminated groundwater on site as well as the
groundwater at the perimeter of the waste boundaries, which is the
point of compliance for the groundwater standards. Alternative 4.
would provide additional effectiveness over Alternative 3 and would
satisfy the compliance with ARAR criteria. However, given the
relatively low concentrations beyond the waste limits and the
limited number of sampling rounds from the RI, the additional
effectiveness in reaching clean-up objectives with Alternative 4
over Alternative 3 cannot be predicted at this time. The
performance of a pump and treat system in Alternative 4 would be
reviewed regularly to assess its effectiveness in achieving
remediation goals.
2. Primary Balancing Criteria
Five primary balancing criteria are used to identify major trade-
offs between the remedial alternatives which satisfy the two
threshold criteria. These trade-offs are ultimately balanced to
identify the preferred alternative and to select the final remedy.
Because Alternatives 1 and 2 do not satisfy the threshold criteria,
they will not be evaluated by the primary balancing criteria.
a. LONG-TERM EFFECTIVENESS AMD PERMANENCE
Alternative 3 would include extraction of contaminated groundwater
in the Non-Contiguous Fill Area that will also reduce the loading
of contamination into both the Southern and Southeast Flow Paths.
This reduction in loading, in combination with the reduction in
loadings achieved by the SCOD remedial components, is expected to
lower contaminant concentrations in these flow paths. Although
this alternative does not directly remove contaminants downgradient
of the Old Fill area and Southeast Fill area, U.S. EPA believes the
present concentrations which are already close to MCLs would be
attenuated through natural processes such as degradation,
adsorption, and dilution. The contaminants found in these
downgradient flow paths represent a potential future use risk of l
x 10** and a hazard index greater than one. Additional information
obtained from monitoring after the remedy has been installed will
be used to confirm the clean-up time frame and the capability of
the remedy to keep concentrations at or below clean-up objectives
at all monitoring points. Alternative 3 would be supplemented, if
necessary, through additional remedial actions, including expansion
of the groundwater pump and treat action, to assure achievement of
the clean-up standards. This Alternative, in combination with the
previous actions, would provide long term effectiveness through
minimizing the additional contaminants reaching the aquifer and
continuous reduction of existing contaminants in the groundwater.
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Alternative 4 would provide long term effectiveness similar to
Alternative 3 with the addition of immediate groundwater extraction
along the perimeter of the fill areas. The installation of
extraction wells along the southern and/or southeast flow paths
would further contain the movement of groundwater contamination
currently in these areas and therefore potentially reduce
concentrations in a shorter time period. However, long term
effectiveness would not be substantially affected by Alternative 4
since the additional actions do not address the main source of
contamination. The primary difference between Alternative 4 and
Alternative 3 is that additional containment through extraction
will occur in Alternative 4. Both alternatives would reduce the
level of residual health risk associated with existing groundwater
contamination in proportion to the reduction of groundwater
contaminants removed from the aquifer. However, many of the
organic and inorganic contaminants present are expected to be
reduced to levels near the analytical detection limit in the
extracted groundwater, causing difficulty in verifying the
treatment's effectiveness in reaching clean-up standards.
b. REDUCTION IN TOXICITY, MOBILITY, OR VOLUME THROUGH
TREATMENT
Alternatives 3 and 4 provide groundwater extraction and treatment
that is intended to remove and treat those contaminant
concentrations from the aquifer and limit potential migration.
Treatment would occur on all extracted groundwater through air
stripping for VOCs and precipitation for inorganics. Air stripping
is a proven technology in effectively removing VOCs from water as
well as precipitation is a proven method for removing inorganics.
There would be no difference in treatment technologies between
Alternatives 3 and 4 as currently proposed. However, under both
alternatives, if results from the remedial design pilot test
indicate that additional treatment is necessary to reach discharge
standards then treatment technologies may be modified. Alternative
4, and to a lesser extent Alternatives 4A and 4B, would restrict
mobility of groundwater contamination through hydraulic control of
the aquifer to a greater extent than Alternative -3. Because the
additional volume of groundwater addressed in Alternative 4 is not
nearly as highly contaminated as the groundwater that would be
addressed under Alternative 3, the additional contamination and
risk reduction provided by Alternatives 4, 4A, and 4B is not
proportional to the additional volumes extracted and cost expended.
c. SHORT-TERM EFFECTIVENESS
None of the alternatives would pose a substantial risk to the
community, workers, or the environment during remedial actions.
Precautionary actions, through the remedial action health and
safety plan, would address risks to on-site workers and potential
off-site risks posed by cleanup-related activities.
Installation of groundwater extraction wells, treatment facilities,
and a discharge system can be accomplished in one construction
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season, with minimal disturbance of contaminated soils. This time
frame may be extended, if necessary, to gather information during
the remedial design pilot test and if supplemental activity is
required in response to monitoring results. The risks of
construction activities for Alternatives 3 and 4 are adequately
managed through the use of personal protective equipment for
construction workers.
d. XMPLEMENTABILXTY
Implementability refers to the technical and administrative
feasibility of constructing and operating the remedy described in
the alternative. Alternatives 3 & 4 would both be technically
feasible alternatives. Groundwater extraction wells with air
stripping for organics and precipitation for inorganics are common
technologies that have been proven feasible and effective on
numerous occasions. All materials and services required for either
alternative would be readily available and therefore technical
feasibility is not a concern for either alternative.
Alternative 3 would require discharge on-site to an infiltration
basin. There would not be the institutional requirements of
obtaining permission from local authorities or private citizens for
this work. Assuming that discharge ARARs (specifically, BAT &
PALs) were met for the State of Wisconsin, Alternative 3 would be
administratively feasible. Under Alternatives 4, 4A or 4B,
discharge of treated groundwater would likely take place at the Fox
River. The reasoning for this discharge location is the effluent
volume would likely be greater than the capacity of the on-site
infiltration basin. Discharging treated groundwater to the Fox
River could be difficult to execute for administrative reasons.
The Cities of Muskego and Big Bend would need to approve the
project as well as Waukesha County. In addition, easements would
need to be obtained from several private property owners to
construct the pipeline and lift/pump stations and a WPDES permit
would be required. The pipeline would need .to cross at -least eight
roads, including one county highway. Based on these factors the
administrative feasibility of Alternatives 4, 4A and 4B would be
questionable.
e*. COSTS
The estimated costs for all of the FS alternatives are listed
below. The first column list the capital or construction costs for
the project. The second column are the costs to operate the
remedial system once it is constructed. The final column is the
Present Net Worth.
Annual
Capital Cost O&M Costs Total Cost
1.0 0 0
2. $145,000 $161,000 $ 2,620,000
3. $1,218,000 $417,000 $ 7,410,000
4. $3,464,000 $950,000 $ 16,700,000
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4a. $3,026,000 $842,000 $ 14,900,000
4b. $3,207,000 $869,000 $ 15,800,000
The estimated time frame for Operation and Maintenance costs is 30
years with a 5% discount factor. As with all costs estimated in a
Feasibility Study, a range of -30% to +50% is applicable to cover
variations in actual cost.
3. Modifying Criteria
a. STATE ACCEPTANCE
The WDNR has been the support agency for the RI/FS and has reviewed
this ROD. The WDNR concurs with the selected remedial action. In
addition, the WDNR does not feel that Alternatives 1 or 2 are
protective or would attain ARARs. Therefore, Alternatives 1 and 2
are not acceptable to the State. Sections NR 140.24(2) and NR
140.26(2), Wis. Adm. Code, outline the response objectives that
apply to this site. These sections specify that contaminated
groundwater be restored in a reasonable period of time, and,where
technically and economically feasible, be restored to achieve PALs.
Alternative 3 is acceptable to the WDNR given that there will be
continuous monitoring and the requirement to take additional
remedial actions to ensure progress towards achieving clean-up
goals in a reasonable period of time. Specifically, a phased
approach that allows adjustments to the SCOU and groundwater remedy
is imperative for the State under Alternative 3. Alternative 4 is
supported by the State as well.
b. COMMUNITY ACCEPTANCE
Comments have been submitted by the community, local government
officials, and potentially responsible parties (PRPs). Issues
presented in the comments were directed toward the inclusion of
groundwater monitoring at private residences surrounding the site.
Comments and responses to those comments are described in greater
detail in the Responsiveness Summary attached to this ROD.
Alternative 4 would require additional public comment from the
community, especially residents of Big Bend. Given the number of
easements that would be required for installation of the discharge
line it is expected- that additional information would have to be
provided to the community prior to the selection of this
alternative, because that requirement was not sufficiently clear in
the Proposed Plan.
C. Summary
Based on a comparison of the nine criteria, Alternatives I and 2 do
not provide protection from all of the potential risks at the site
and do not comply with ARARs. They therefore do not meet the
threshold test for selection of a remedial alternative at the site.
Alternative 3 would be .protective of human health by addressing
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groundwater contamination in the Non-Contiguous Fill Area.
'Concentrations of contaminants were greatest in this area, so
addressing that area would provide the most efficient reduction of
groundwater contamination through extraction and treatment. In
addition, groundwater from this area is connected to the Southern
and Southeast flow paths. Addressing that area would contribute to
the reduction of contaminants downgradient of the fill areas and
help achieve clean-up goals at the point of compliance.
Alternative 4, similar to Alternative 3, would fulfill both
threshold criteria. Protectiveness to human health and the
environment and compliance with ARARs would be provided through
either of these groundwater extraction and containment remedies.
As noted in the Proposed Plan, an important element of compliance
with these criteria for Alternative 3 is the implementation of
additional measures if monitoring data demonstrates that the
Alternative, in combination with the SCOU, is not contributing to
achievement of groundwater clean-up standards in the South and
Southeast flow paths.
Alternatives 3 and 4 would both satisfy the long term effectiveness
and permanence criteria. Both alternatives would provide adequacy
and reliability of controls and the magnitude of residual risk
associated with these Alternatives is minimal. Treatment would be
identical for Alternatives 3 and 4 in all respects except that
Alternative 4 would treat a greater volume of water.
Construction of either Alternative 3 or 4 would not present any
significant risk to the community. By following proper site safety
procedures any risk commonly associated with this type of
construction work would be alleviated. Environmental impacts would
be minimal or non-existent assuming that proper handling and
disposal procedures are followed. All of these factors contribute
to both Alternatives satisfying the short-term effectiveness
criteria.
Since Alternative 3 would require construction of a groundwater
pump and treat system primarily within the property boundary there
are no anticipated technical or administrative difficulties at this
time. Extraction well installation, air stripping, and
precipitation are standard technologies that would be technically
feasible and practicable to construct. Therefore Alternative 3
would be impleraentable and satisfy this criteria. Alternative 4,
however, would likely require agreements with two municipalities,
Waukesha County, the WDNR and several private residences to
construct a discharge pipeline from the site to the Fox River and
obtain a WPDES discharge permit. While U.S. EPA has coordinated
projects similar in nature, there are no assurances that these
administrative requirements can be completed.
The Present Net Value costs for Alternative 3 total $7,410,000.
Capital costs are estimated at $1,218,000 and operational costs at
$417,000 per year for 30 years. Alternative 4 has Present Net
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Value costs as follows; $14,900,000 (4a, Southeast Flow Path),
$15,800,000 (4b, Southern Flow Path), and $16,700,000 (4a & 4b) .
Costs for Alternative 4 are substantially greater than Alternative
3 due primarily to the .greater costs for Operation and Maintenance
over the 30 year period. The actual capital costs are similar for
both alternatives. However the volume of extracted groundwater in
Alternative 4 would be double the amount in Alternative 3. To the
extent additional phases are required upon implementation of
Alternative 3, the present value costs of Alternative 3 would still
be significantly lower than Alternative 4 because: (1) expansion of
the system would be deferred for several years, substantially
reducing the present value of those costs; and (2) contaminant
reductions achieved by the SCOU and operation of the system in the
NCF area may permit any later phases to be more limited than what
is anticipated in Alternative 4.
The WDNR concurs with Alternatives 3 and 4 but does not concur with
either Alternative 1 or 2. WDNR does not believe alternatives 1 or
2 are protective of human health or comply with ARARs. However,
Alternative 3 is acceptable to WDNR given tha't the remedy be
implemented in a phased approach and that the effectiveness of the
remedy is measured periodically, and would be expanded if necessary
to achieve clean-up standards. The WDNR also concurs with
Alternative 4 and believes this extraction and containment option
provides the greatest chance of complying with ARARs in the
shortest .period of time. It is expected, however, that Alternative
3 would achieve compliance with groundwater ARARs in an acceptable
time period at substantially lower cost.
IX. THE SELECTED REMEDY
Based on the evaluations of the alternatives, U.S. EPA and the
State of Wisconsin believe that the selected remedy (Alternative 3)
will be protective of human health and the environment, comply with
ARARs, be cost effective, and will utilize permanent solutions to
the maximum extent practicable.
The selected remedy includes:
• Groundwater monitoring,
• Groundwater pumping test(s),
• Groundwater" extraction in the vicinity of the Non-
Contiguous Fill Area,
• On-site treatment of extracted water for contaminants as
deemed necessary from tests during remedial design,
• Discharge of treated water to an infiltration basin or
MMSD, as deemed necessary during remedial design pilot
tests,
• Disposal of treatment residuals, if necessary,
• Monitoring and evaluation of the effectiveness of the
groundwater extraction system in achieving progress toward
clean-up standards, and
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Expansion of the system if data on the performance of the
system indicates that expansion is necessary to make
progress toward clean-up standards.
Alternative 3 will be implemented in a phased approach in order to
gather data to determine the progress achieved in effectuating
clean-up objectives. Therefore implementation of limited pump and
treat in the Non-Contiguous Fill Area would occur in conjunction
with pilot scale phase testing to determine aquifer characteristics
and evaluate discharge .and treatment options. Groundwater
monitoring will be conducted to correspond with the pilot scale
testing and continue after the remedy is constructed. Monitoring
results will be used to periodically evaluate effects of
groundwater extraction on the contaminant plume. The monitoring
results will also be used to better define the plume within the
Non-Contiguous Fill Area and downgradient of this area. Additional
measures to effectively evaluate groundwater plume and aquifer
characteristics may be implemented as deemed necessary by U.S. EPA,
in consultation with WDNR, during the pilot scale test.
Pre and post-test groundwater quality testing will be performed for
treatment system design and evaluation purposes. A Pilot-Scale
Evaluation Report (PER) will be submitted for approval by U.S. EPA,
in consultation with WDNR. This report would outline the results
of the pilot scale test and provide recommendations for treatment
system design, discharge location and rates, monitoring locations
and recommendations for additional action if sufficient progress
toward achieving clean-up goals has not been attained. In
addition, the PER would include a plan for measuring the progress
towards clean-up goals. Attachment B. "Performance Evaluations for
Pump and Treat Remediations" provides information on mathematical,
statistical, or graphical methods to evaluate the performance of
pump and treat remediations. This reference is consistent with
U.S. EPA guidance "Methods for Monitoring Pump and Treat
Performance" June 1994. The decision on which method is more
suitable for the Muskego site will be based on the pilot scale test
and will be made by U.S. EPA, in consultation with WDNR.
Any additional action beyond adjustments to the original
groundwater extraction system and source control measures would
require review by U.S. EPA in consultation with WDNR. Actions that
would require an off-site surface water discharge of extracted
water would likely require a ROD Amendment and therefore public
comment would be solicited.
As previously mentioned, this alternative allows for contingency
actions as determined necessary by U.S. EPA, in consultation with
WDNR. The objective of the groundwater monitoring program will be
to provide information in order to measure progress achieved in
effectuating the clean-up objectives. Unless progress toward
clean-up objectives has been demonstrated by the first periodic
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review, contingency actions will have to be implemented. For
example, if monitoring wells show, after a sufficient number of
monitoring events, that state and federal groundwater standards are
consistently met, the system could be turned off. If groundwater
standards are not obtained, but a decreasing trend is shown, then
the system would continue to be operated with continued monitoring.
If contaminant concentrations stay at the same level or are
increasing, then contingency actions may be taken. These actions
could include, but are not limited to: additional source control
measures such as leachate extraction, alternate 'pumping or pulse
pumping at current groundwater extraction wells, or installation of
additional groundwater extraction wells. This final option may
require an Explanation of Significant Difference or ROD Amendment
if modifications have significant technical or cost implications.
Determination of adequate progress towards clean-up goals will be
measured periodically after system start up. The first evaluation
would occur within 5 years after the implementation of the SCOU
actions. The clean-up goals for the site are the NR 140 Preventive
Action Limits (PALs), which must be met at and beyond the waste
boundaries (edge of waste). Consistent with Section
300.430(a) (1) (iii)(F), U.S. EPA expects to return useable
groundwater at the Site to beneficial use wherever practicable,
within a timeframe that is reasonable given the particular
circumstances of the Site. -
A periodic review, as described in Alternative 3, will be prepared
that evaluates all remedial actions performed at the site against
clean-up objectives. These reviews will provide recommendations on
implementing additional remedial actions, such as installing
additional groundwater or leachate extraction wells, and/or
adjusting current system operations. One goal of this alternative
will be to estimate the time frame to reach clean-up objectives.
This will be facilitated through continued, long-term performance
monitoring of the site.
The remedial action objectives and clean-up goals for this Final
Remedy are presented in Section VII of this ROD. The remedial
action objectives include:
* Reduction of the migration of contaminants of concern from
the Fill Areas.
* Reduction of the concentrations of contaminants of concern
in groundwater at the site to acceptable risk levels.
* Reduction of groundwater concentrations of contaminants of
concern at the site to meet Federal Maximum Contaminant
Levels (MCLs) and State NR 140 Enforcement Standards (ESs)
and Preventive Action Limits (PALs) at and beyond the waste
boundaries (edge of waste).
* Return useable groundwater at the Site to beneficial use
wherever practicable, within a timeframe that is reasonable
given the circumstances of the Site.
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* Further evaluation of the groundwater and plume
characteristics in the Non-Contiguous Fill Area and
downgradient of this area during pilot scale tests.
Table 10 lists a detailed cost summary for the selected remedy.
U.S. EPA and the WDNR believe that the selected remedy, in
combination with the previous actions, will achieve the remedial
action objectives for this remedy. To the extent additional phases
are required upon implementation of Alternative 3, the present
value costs of Alternative 3 would still be significantly lower
than Alternative 4 because: (1) expansion of the system would be
deferred for several years, substantially reducing the present
value of those costs; and (2) contaminant reductions achieved by
the SCOU and operation of the system in the NCF area may permit any
later phases to be more limited than what is anticipated in
Alternative 4.
X. STATUTORY DETERMINATIONS
A. Protection of Human Health and the Environment
The selected remedy provides adequate protection of human health
and the environment through a phased approach to groundwater
monitoring, extraction and treatment. This builds on previous
response actions which were designed to reduce possible sources for
additional contamination of groundwater and to limit direct
exposure to contamination.
As described in the SCOU ROD, the effect of the Site on wetlands
located southeast of the Site have been mitigated through source
controls. Extracting and containing contaminated groundwater
should provide further protection for those wetlands.
The groundwater operable unit, building on the SCOU remedy, will
attempt to restore groundwater to the State ESs and PALs and to
Federal MCLs.
B. Attainment of ARARs
The selected remedy will be designed to meet all applicable, or
relevant and appropriate requirements (ARARs) under federal, and
more stringent state environmental laws. A list of ARARs for the
site is contained in the alternative arrays section of the FS. The
primary ARARs that will"be achieved by the selected alternative
are:
1. Action Specific
Resource Conservation and Recovery Act, as amended [42 U.S.C.
S 6901 at seq.]; Wisconsin Environmental Protection Law, Hazardous
Waste Management Act [Win. Stat. 5 144.60-74]
Most RCRA requirements are administered under the State of
Wisconsin's implementing regulations. U.S. EPA does not have
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sufficient evidence to demonstrate that listed RCRA wastes were
disposed of at the site. RCRA requirements are therefore not
applicable to the site, except to the extent that new hazardous
wastes (such as treatment residuals) are generated during the
course of the remedy. Several other RCRA regulations, although not
applicable, address problems or circumstances very similar to those
encountered at this site and are therefore relevant and
appropriate. However, the remedy will comply with the following
applicable requirements:
Wis. Admin. Code NR 605; 40 CFR 261 - Identification of Hazardous
Wastes. Provides requirements for determining when a waste is
hazardous. The substantive requirements of these regulations will
apply to any on-site TCLP testing of treatment residuals and waste
excavated at the site (e.g. in constructing wells) which may be
disposed of off-site.
Wis. Admin. Code NR 615; 40 CFR 262 - Standards Applicable to
Generators of Hazardous Waste. Provides requirements for the
shipment of wastes to treatment, storage or disposal facilities.
These requirements may apply to on-site preparations for off-site
shipment of treatment residuals and other wastes.
Wis. Admin. Code NR 620; Department of Transportation Hazardous
Materials Transportation Act [49 U.S.C. § 1801]; 40 CFR 263 -
Standards Applicable to Transporters of Hazardous Waste. Requires
record keeping, reporting and manifesting of waste shipments.
These requirements may apply to on-site preparations for off-site
shipment of treatment residuals and other wastes.
Wis. Admin. Code NR 630.10-17; 40 CFR 264, Subpart B - General
Facility Requirements. Establishes substantive requirements for
security, inspection, personnel training, and materials handling
which are relevant and appropriate to on-site activities involving
excavations and handling of hazardous soils and materials.
Wis. Admin. Code NR 630.21-22;- 40 CFR 264, Subpart D - Contingency
Plan and Emergency Procedures. Establishes substantive
requirements for emergency planning which are relevant and
appropriate for on-site activities involving excavation and
handling of hazardous substances.
Wis. Admin. Code NR 675; 40 CFR 268 - Land Disposal Restrictions.
Requires that hazardous wastes cannot be land disposed unless they
satisfy specified treatment standards and imposes record keeping
requirements on such wastes. These requirements apply to on site
activities related to off-site disposal of any treatment residues
or other hazardous wastes.
Clean Water Act of 1977, as amended [33 U.S.C. 5 1317]
40 CFR 403 - Pretreatment Standards. To the extent waste waters
will be discharged into a Publicly Owned Treatment Works (POTW) ,
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the selected remedy would satisfy both general and specific
requirements to protect against damage to POTWs. Any waste to be
discharged to a POTW must, if necessary, be treated to satisfy
these standards prior to discharge. These pretreatment
requirements are administered under NR 211 and 108. The
substantive requirements of these regulations will apply to
collected groundwater to be discharged.
2. Chemical Specific
Clean Air Act [42 U.S.C. S 7401 et seq.]; Wisconsin Environmental
Protection Law, Subehapter Ill-Air Pollution [Wis. Stat. 144.30-
144.426]
40 CFR 50; Wis. Admin. Code NR 404, 415-449 - Emissions Standards.
Establishes standards for emission of pollutants into the ambient
air and procedures for measuring specific air pollutants.
Groundwater treatment or pretreatment may require removal of VOCs
before discharge. The need for treatment of air emissions produced
by this process would be evaluated based on substantive
requirements of Wis. Admin. Code NR 445. If emissions are expected
to exceed those standards, the selected remedy will include
treatment of air emissions. Handling of contaminated soils during
excavation could also cause air emissions of VOCs, particulates,
fugitive dust or other contaminants which could adversely effect
human health and the environment. The design of the remedy will
reduce such emissions to acceptable levels or provide for treatment
to satisfy these standards.
Safe Drinking Water Act [40 U.S.C. S 300 et seq.]
40 CFR 141, Wis. Admin. Code NR 109 - Maximum Contaminant Levels
(MCLs) . MCLs establish drinking water standards for potential and
actual drinking water sources. MCLs have been exceeded at the site
in the shallow aquifer, which is classified as a potential drinking
water source. The selected remedy, building on the SCOU remedy, is
intended to achieve compliance with MCLs and non-zero Maximum
Contaminant Level Goals.
Wis. Admin. Code NR 140 - Groundwater Quality Standards. Provides
for groundwater quality standards including Preventive Action
Limits (PALs), Enforcement Standards (ESs), and (Wisconsin)
Alternative Concentration Limits (WACLs). The selected remedy,
building on the SCOU remedy, is intended to achieve compliance with
PALs at and beyond the waste boundary (edge of waste) . To the
extent it is subsequently determined that it is not technically or
economically feasible to achieve PALs, NR 140.28 provides
substantive standards for granting exemptions from the requirement
to achieve PALs. Such exemption levels may not be higher than the
ESs.
Discharge to an infiltration basin would meet ch. NR 220, Wis. Adm.
Code, WPDES Best Available Technology (BAT) requirements, at the
point of discharge and ch. NR 140, Wis. Adm. Code, PALs for all
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contaminants in the groundwater at a point directly below the
discharge zone. To the extent it is subsequently determined that
it is not technically or economically feasible to achieve PALs, NR
140.28 provides substantive standards for granting exemptions from
the requirement to achieve PALs. Such exemption levels may not be
higher than the ESs.
Resource Conservation and Recovery Act, as amended [42 T7.S.C.
S 6901 et aeg.]; Wisconsin Environmental Protection Law, Hazardous
Waste Management Act [Win. Stat. § 144.60-74]
Most RCRA requirements are administered under the State of
Wisconsin's implementing regulations. U.S. EPA does not have
sufficient evidence to demonstrate that listed RCRA wastes were
disposed of at the site. These RCRA regulations, although not
applicable, address problems or circumstances very similar to those
encountered at this site and are therefore relevant and
appropriate.
Wis. Admin. Code NR 635.09; 40 CFR 264.94 - Concentration limits.
Establishes concentration limits in groundwater for certain
hazardous constituents related to a hazardous waste management
unit.
40 CFR 265.1032-33 - Air emissions standards for process vents.
Establishes emissions standards for certain air stripper
operations. If air stripping is used to remove VOCs from extracted
groundwater, air stripper emissions would meet applicable standards
under these regulations. As with the Clean Air Act standards
described above, treatment of these air stripper emissions would be
included if necessary to meet RCRA air emission standards.
Wisconsin Environmental Protection Law, Subchapter IZ-Water and
Sewage [Wis. Stat. § 144.02-27]; Clean Water Act of 1977, as
amended [33 U.S.C. S 1311-17]
Wis. Admin. Code NR 102 and 105 - Surface water quality standards.
NR 102 creates an antidegradation policy for all waters of the
State and prohibits toxic substances in surface waters at
concentrations which adversely affect public health or welfare,
present or prospective water supply uses, or protection of animal
life. The selected remedy, building on the SCOU remedy, will
achieve compliance any substantive requirements of these
regulations that constitute ARARs for discharge into the retention
pond on-site, including ch. NR. 220, Wis. Adm. Code, WPDES Best
Available Technology (BAT) requirements, at the point of discharge
and ch. NR 140, Wis. Adm. Code, PALs at a point directly below the
discharge zone. To the extent it is subsequently determined that
it is not technically or economically feasible to achieve PALs, NR
140.28 provides substantive standards for granting exemptions from
the requirement to achieve PALs. Such exemption levels may not be
higher than the ESs.
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40 CFR 131 - Ambient Water Quality Criteria. Establishes pollutant
concentration limits to protect surface waters. These and other
water pollution discharge limits are administered under the
Wisconsin Pollutant Discharge Elimination System (WPDES) permit
program. The selected remedy would satisfy both general and
specific, substantive requirements for discharge to on-site surface
waters, namely the retention basin. Any waste to be discharged to
a surface water must, if necessary, be treated to satisfy these
standards prior to discharge. These treatment requirements are
administered under NR 200 and 220. The substantive requirements of
these regulations will apply to collected groundwater to be
discharged. The source control remedy is intended to eliminate
contaminated surface runoff at the site. To the extent
contaminated runoff is channeled directly to a surface water body,
however, that runoff must comply with any applicable concentration
limits.
3. Location Specific
Clean Water Act of 1977, as amended [33 U.S.C. S 1344]
Executive Order 11990 and 40 CFR 6 - Protection of Wetlands.
Wis. Admin. Code NR 103 - Water Quality Standards for Wetlands.
These requirements provide for protection against loss or
degradation of wetlands. Contamination in surface water runoff and
groundwater will be controlled so that it does not have an adverse
impact on nearby wetlands.
C. Cost Effectiveness
The selected remedy provides overall cost-effectiveness. Phased
extraction that focuses on the most highly contaminated groundwater
first adds a significant degree of permanence, as well as a further
opportunity to assess the effectiveness of the SCOU remedy in
reducing new contaminant loadings in groundwater. Thus, the effect
of these remedial activities on compliance with ARARs and
protection of human health and the environment will be analyzed
before requiring a broader, more costly groundwater extraction and
treatment system.
D. Utilization of Permanent Solutions and Alternative
Treatment Technologies to the Maximum Extent Practicable
The selected alternative represents the best balance of
alternatives with respect to the nine evaluation criteria described
in Section VIII. The selected alternative adopts a phased approach
to address groundwater contamination, extracting and treating
contamination that exceeds regulatory standards.
E. Preference for Treatment As A Principal Element
By extracting and treating the contaminated groundwater, the
selected remedy satisfies the statutory preference for remedies
that employ treatment as a principal element to permanently and
significantly reduce toxicity, mobility, or volume of hazardous
substances.
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XI. RESPONSIVENESS SUMMARY
This Responsiveness Summary has been prepared to meet the
requirements of Sections 113 (k) (2) (B) (iv) and 117 (b) of the
Comprehensive Environmental Response, Compensation, and Liability
Act (CERCLA) of 1980, as amended by the Superfund Amendments and
Reauthorization Act (SARA) of 1986, which requires U.S. EPA to
respond "...to each of the written or oral presentations" on a
Proposed Plan for remedial action. This Responsiveness Summary
summarizes comments and concerns expressed by the public and other
interested parties in written and oral form received by U.S. EPA on
the recommended remedy.
On October 3, 1994, U.S. EPA made available to the public for
review and comment the FS and Proposed Plan for groundwater at the
Muskego Sanitary Landfill. This comment period was extended for 60
days until December 2, 1994..
U.S. EPA received comments at the public meeting on October 17,
1994, at the Muskego City Hall. Additional written comments were
also submitted during the comment period.
Cormi|ent Period
Comments received during the public comment, period are summarized
in this section. Some of the comments have been paraphrased in
order to effectively summarize them in this document. The reader
is referred to the public meeting transcript and copies of written
comments submitted. All are available for review at the
information repositories.
Comment; One commenter believes Alternative 2, Groundwater
Monitoring, will provide protection to human health and the
environment and therefore is a viable alternative.
The commenter stated that the previous removal actions and source-
control measures, coupled with natural mitigating processes are
expected to limit further groundwater contamination and result in
a reduction of groundwater contaminant concentrations from those
identified in the Remedial Investigation Report (RI) .
The commenter views that in order to effectively evaluate the
impact of the SCOU activities on groundwater there needs to be
adequate time after completion of these activities to monitor
groundwater contamination. In addition, nearby private residences
have been connected to public water supplies and institutional
controls that prohibit private well installation within 1200 feet
of an existing landfill are in effect. The commenter believes that
these conditions preclude the hypothetical exposure associated with
the potential future use of the site and therefore Alternative 2 is
a viable remedial option for this site.
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U.S. EPA Response: U.S. EPA agrees that the previous removal and
SCOU activities will have a positive effect on groundwater quality
in the vicinity of this site. U.S. EPA believes these actions will
contribute to the reduction of contaminant loading into the
groundwater and coupled with natural mitigating processes will
reduce contamination levels in groundwater. However, given the age
and design characteristics of the source areas and the high level
of contamination in the groundwater near the Non-Contiguous Pill
Area, U.S. EPA does not believe that these actions will adequately
address threats posed by the existing contamination in the
groundwater nor completely eliminate additional contaminant loading
into the groundwater.
The State prohibition on the installation of drinking water wells
within 1,200 feet of the edge of waste may not always be
effectively enforced, since it is dependent on the well driller or
property owner contacting the WDNR prior to well installation.
Also, the WDNR can grant variances from the prohibition, so the
prohibition is not absolute, even if the WDNR is contacted.
Therefore, the effectiveness of institutional controls relating to
water supply well prohibition is dependant upon the site owner or
contractor contacting the WDNR, and is not absolute, even if the
WDNR is contacted.
U.S. EPA also agrees that one of the objectives of a phased
approach to this remedy is to gather additional information on the
effect of the previous remedial activities at the site. However,
regardless of current risk or hypothetical future use scenarios of
the landfill property, one of the objectives of this final remedial
action is to determine how to effectively prevent or retard the
migration of contamination already within the aquifer which will
not be affected by SCOU actions. U.S. EPA believes that prior
actions in combinations with natural processes may be effective in
the outer limits of the plume beyond the source areas but, does not
believe natural mitigating processes will be effective in areas of
higher contamination near a source, such as the Non-Contiguous Fill
Area. Therefore U.S. EPA disagrees with the comment that
Alternative 2 is a fully protective alternative. For that reason,
the remedy initially targets only the source area with the highest
levels of contamination. This provides adequate time, as the
commenter suggests, to evaluate the impact of clean-up activities
on other areas of the site.
Comment: One commenter believes that Alternative 3, if selected,
should be implemented in a phased approach to gain the necessary
data to determine the progress towards, and probability of,
actually achieving clean-up objectives. The commenter also
believes that a comprehensive pilot scale test be included in the
Alternative with the purpose of determining groundwater
characteristics and evaluating discharge and treatment options.
The commenter has indicated that an evaluation of the effectiveness
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of groundwater extraction in capturing contaminants and the
potential for achieving groundwater clean-up objectives should be
performed during the pilot test phase. Also a mechanism to re-
evaluate the need for further groundwater extraction should be
provided if necessary. Finally, the commenter believes that if
results from the evaluation process indicate that only if the
groundwater extraction will achieve these objectives and natural
attenuation is ineffective in achieving the objectives should a
long-term limited .pump and treat system be installed and operated.
U.S. EPA Response: U.S. EPA agrees with the commenter that
Alternative 3 should be implemented in a phased approach to
accomplish the objectives associated with this ROD. U.S. EPA also
believes that a pilot scale study should be completed as indicated
in the description of Alternative 3. A Performance Evaluation
Report will be required that evaluates groundwater characteristics,
discharge and treatment options as well as other parameters. This
study will, as the commenter suggests, be used to design an
effective system. In addition, a mechanism to evaluate the
progress toward achieving the groundwater clean-up objectives not
only during the pilot scale test but during an extended duration
will be required.
U.S. EPA does not agree with the suggestion that only if the
groundwater extraction system is proven effective and natural
attenuation is proven ineffective in the pilot test should a long-
term limited pump and treat system be installed. Groundwater pump
and treat systems are effective in removing and containing
contamination. The pilot test is aimed at optimizing the design of
a system, not to demonstrate the need for one. The ROD and the
underlying documents demonstrate the need and show that the system
will move the site toward achieving groundwater clean-up standards
and addressing unacceptable levels of contamination more
expeditiously.
Comment: One commenter who lives near the site would like their
private well sampled for Volatile Organic Compounds.
U.S. EPA Response: Private wells near the site, including the
commenter's well, were sampled in August 1991 by U.S. EPA. There
was no contamination found during this sampling round in any of the
wells. Groundwater monitoring since 1991 has not indicated a
change in groundwater contamination levels, therefore there is no
reason to believe that contamination would have reached this well
from the site. In addition, all residences in the vicinity of the
site have been connected to public water thereby eliminating a
concern for potential exposure through ingestion. U.S. EPA has
provided this comment to the State authorities and recommends the
commenter contact the local WDNR office for further information on
procedures for private well sampling.
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Comment: One commenter stated that all private and monitoring well
results of all tests taken on her property be forwarded to her.
U.S. EPA Response: U.S. EPA will ensure that sampling results
related to the commenter's property from the Interim Groundwater
Monitoring Plan will be forwarded to the commenter as these results
become available. Additional information regarding test results is
available at the information repositories located at the Muskego
City Hall and the Muskego Public Library.
Comment: One commenter from the City of Big Bend provided U.S. EPA
with sampling information provided to him by the WDNR for his
business. The commenter expressed concern for citizens that are
not on public water and what is being done for them.
U.S. EPA Response: U.S. EPA thanks the commenter for this
information. If more information is needed, the Agency will
certainly contact him. The site currently does not impact any
private drinking wells in the City of Big Bend. All private
residences near the site have been connected to public water. A
few residences retained their private well for non-potable uses
such as watering their gardens and yard.
Comment: One commenter expressed concern that it was unclear how
future public comment would be incorporated into the process of
selecting and implementing additional remedial actions for
Alternative 3.
U.S. EPA Response: p*f>* EPA acknowledges the concern for public
input on future decisions regarding this project. Contingency
measures for Superfund projects are described in three categories.
Non-significant changes, Significant changes and fundamental
changes to the decision document are the means to make changes to
a selected remedy. Non-significant changes are usually adjustments
that relate to design, construction or administrative factors but
do not significantly change or modify the remedy. These changes do
not effect the overall scope of the remedy and are usually
documented in the post-decision document file. This information
can be placed within the information repository at the discretion
of the project manager.
Significant changes are generally incremental changes described in
a document called an Explanation of Significant Difference (BSD).
These changes are communicated to the public through a public
notice usually published in one or more of the local newspapers.
In addition, changes under an BSD are placed in the information
repository. The project manager has the discretion to seek public
comment on the ESD.
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Finally, any fundamental change to the remedy would require a ROD
Amendment which requires the agency to open a 30 day public comment
period. During this period the agency would notify the public
through newspaper advertisements and solicit public review and
comment on the Amendment. A public meeting would also be conducted
by the agency during the comment period.
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