United States
Environmental Protection
Agency
Office of
Emergency and
Remedial Response
EP AIRODIR05-91/181
September 1991
COfY I
PS12..- C(641'Z..?i
oEPA
Superfund
Record of Decision:
Stoughton City Landfill, WI
~~ l~~~~~~~~ ~~~e;tion Agency
8 echn/callnformation Center
P~~Je~~~~ p~tr~io~h Aoor
HazatdOUS Waste ~ . -.>
InfOff'l'tQtlon ~e...C~';
US EPA -RegIon .3 . -. .. ~':
PhtkJd8IphIa. PA. 19107
EPA Report Collection
Information ~esource Center
US EPA RegIOn 3
philadelphia, PA 19107
-------
50272-101
REPORT DOCUMENTATION T 1. REPORT NO. I ~ 3. Reclpienta Acce88Ion No.
PAGE EPA/ROD/R05-91/181
4. T1I8 and SUbIIIII 5. Report D8I8
SUPERFUND RECORD OF DECISION 09/30/91
Stoughton City Landfill, WI
First Remedial Action - Final 6.
7. AuIhor(a) 8. Perfonning Organlzallon Rept. No.
8. Perfonning OrgalnlDtlon Name and Add- 10. ProjectlTuklWork Unit No.
11. ConIract(C) 01' Gr8nt(G) No.
(C)
(G)
1~ Sponaoring Organization Name and Addre88 13. Type of Report & Period Covered
U.S. Environmental Protection Agency r 800/000
401 M Street, S.W.
Washington, D.C. 20460 14.
15. SUppIemenI8ry No-
16. Ab8tr8ct (Umlt: 200 wolda)
The 27-acre Stoughton, City Landfill site is a former waste disposal facility in
Stoughton, Dane County, Wisconsin. The site was an uncontrolled dump site from 1952
to 1969, and later from 1969 to 1977 operated as a State-licensed landfill covering
approximately 15 acres. Land use in the area is predominantly agricultural and
residential, with several wetlands areas located adjacent to the site. In addition,
part of the site lies within the 100-year floodplain of the Yahara River, located
west of the site. From 1954 until 1962, liquid wastes were commonly poured over
garbage and burned. In addition, some liquid wastes were poured down holes drilled
to test auger drilling equipment. From 1969 to 1977, both solid and liquid municipal
wastes were disposed of at the Stoughton Landfill. In 1977, the State required that
the site be closed and initiated closure activities that included constructing a
trash transfer station, placing cover materials, applying topsoil, and seeding. As a
result of improper disposal activities, a number of investigations were conducted by
the State and EPA that revealed ground water contamination resulting from leachate
discharge and surface water runoff from the landfill. This Record of Decision (ROD)
addresses soil and ground water contaminated by leaching landfilled waste. The
(See Attached Page)
17. ~t An8Iy8I8 L De8cripIora
Record of Decision - Stoughton City Landfill, WI
First Remedial Action - Final
Contaminated Media: soil, debris, gw
Key Contaminants: VOCs (benzene, tetrahydrofurans, toluene, - xylenes), other organics
(PARs), metals (arsenic, chromium, lead)
b. Identlller8lOpen.Ended Terms
c. COSA 11 ReldlGrcq>
18. A'lllilabiity Statement 18. Secl8ity Class (This Report) 21. No. of Pages
None 65
20. Secl8ity Class (Thia Page) n PrIce
None
272 (4-71)
(See ANSI-Z39.18)
See InstTUclions on Revef89
(Fonnetty NTI5-35)
Depllrtment of Commerce
-------
EPA/ROD/R05-91/181
Stoughton City Landfill, WI
First Remedial Action - Final
Abstract (Continued)
primary contaminants of concern affecting the soil, debris, and ground water are VOCs
. including benzene, tetrahydrofurans (THF), toluene, and xylenes; other organics including
PAHS; and metals including arsenic, chromium, and lead.
The selected remedial action for this site includes placing a solid waste disposal
facility cap over the site; excavating wastes in contact with ground water along the
.southeastern and northeastern sections of the site and consolidating these wastes under
the cap; pumping and treatment of contaminated ground water unless additional monitoring
indicates that ground water extraction is not required to achieve compliance with State
quality standards, and subsequent onsite discharge of the treated ground water to the
Yahara River in compliance with NPDES effluent limitations; long-term monitoring of
ground water; and implementing institutional controls and site security measures
including fencing the entire site perimeter. The estimated present worth cost for this
remedial action is $7,546,000, which includes an annual O&M cost of $329,600 for
years 0-5 and $146,600 for years 6-30.
PERFORMANCE STANDARDS OR GOALS: Chemical-specific ground water clean-up goals are based
on State Preventive Action Limits (PALs), and include THF 10 ug/l.
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. - -''':JIll
RlCORD O. DBCISI08
SBLBC'l'BD _DIAL ACTIO.
1'0. TB8
STOUCDft'OB CITY LAIJD.ILL SI'rII
STOUGBTO., WISCO.SIB
SITE NAME AND LOCATION
Stoughton City Landfill site
stoughton, Wisconsin
STATEMENT OF BASIS AND PURPOSE
This decision document presents the selected remedial action for
the Stoughton City Landfill Site ("SCL Site") in Stoughton,
Wisconsin, chosen in accordance with the Comprehensive
Environmental Response, Compensation, and Liability Act of 1980
(CERCLA), as amended by the Superfund Amendments and
Reauthorization Act of 1986 (SARA), and,' to the extent
practicable, the National contingency Plan (NCP). The decision
is based on the Administrative Record for the SCL site. The
attached index identifies the items which comprise the
Administrative Record upon which the selection of the remedial
action is based.
The State of Wisconsin has been consulted and concurs with the
selected remedial action.
ASSESSMENT OF THE SITE
Actual or threatened releases of hazardous substances from this
si te, if not addressed by implementing the remedial action
selected in this Record of Decision, may present an imminent and
substantial endangerment to public health, welfare, or the
environment.
DESCRIPTION OF SELECTED REMEDY
The selected remedial action will be the final remedial action at
the Site. The remedy will address Site risks throuqh placement
of cap over the landfill area which meets the requirements of ch.
NR 504, wis. Adm. Code,in order to minimize the infiltration of
-------
precipitation throuqh the in-place wastes~ extraction and above-
qround treatment of contaminated qroundwater to the west of the
Site unless additional monitorinq indicates that qroundwater
extraction is not required to achieve compliance with the State' s
ch. NR 140 qroundwater quality standards ~ and excavation and
consolidation of wastes in contact with qroundwater alonq the
southeastern and northeastern sections of the site. The major
components of the selected remedial action include:
*
Site security measures includinq the placement of a
fence around the entire Site perimeter~
Placement of a solid waste disposal facility cap (NR
504 cap) over the site~
*
*
Extraction and treatment of contaminated qroundwater,
unless additional monitorinq indicates that qroundwater
extraction is not required to achieve compliance with
the state's ch. NR 140, wis. Adm. Code-, qroundwater
quality standards, and subsequent discharqe to the
Yahara River of the treated qroundwater in compliance
with Wisconsin Pollution Discharqe Elimination System
- (WPDES) effluent limitations~
Excavation of wastes in contact with qroundwater in the
southeastern and northeastern sections of the site, and
consolidation of these wastes under the cap~
*
*
Land use restrictions to prevent the installation of a
well within 1200 feet of the property boundary and to
prevent residential development of the Site~
Lonq-term qroundwater monitorinq to confirm the
effectiveness of the other components of the selected
remedial action.
*
STATUTORY DETERMINATIONS
The selected remedy is protective of human health and the
environment, complies with Federal and state requirements that
are leqally applicable or relevant and appropriate to the
remedial action, and is cost-effective. The remedy utilizes
permanent solutions and alternative treatment (or resource
recovery) technoloqies to the maximum extent practicable and
satisfies the statutory preference for remedies that employ
treatment that reduces toxicity, mObility, or volume as a
principal element, with respect to the qroundwater component of
the selected remedy. However, because treatment of the principal
threats of the site was not found to be practicable, this remedy
does not satisfy the preference for treatment as a principal
element.
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.--..
3
Because this remedy will result in hazardous substances remaining
on-site above health-based levels, a review will be conducted
within five years after commencement of the remedial action to
ensure that the'" remedy continues to provide adequate protection
of human health and the environment. .
~~~/I
-------
State of Wisconsin \ DEPARTMENT OF NATURAL RESOURC'ES
C8noI D. 11 1>y
s.c.."
:,
J . September 30, 1991
101 SouIh w... SIrMt
&ax 1WI
""""" W8OOn8ln 5mI7
saJD WAB'IIi 'TB.eFAX 1ON57~
~AX ""..-mt
TDD 8al8708187
IN REPLY REFER TO: 4440
.
f
t
Mr. Valdas V. Adamkus, Regional Administrator
U.S. Environmental Protection Agency
230 S. Dearborn Street
Chicago, IL 60604
SUBJECT:
.'
Selected Superfund Remedy
Stoughton City Landfill
Dear Mr. Adamkus:
The Department is providing you with this letter to document the State of
Wi sc:ons1n" 5 concurrence on the proposed remedy for the Stoughton City Landfill
Superfund site. The proposal, as identified in the draft Record of Decision
includes the following:
A1t'.rnativl 7a:
Capping with Waste Conso11dat1on, and a Groundwater
Extract1on/Treatment System, unless additional data indicates
that a groundwater extraction systell is' not requ;red to comp1y
with State groundwater quality standards.
A cap with a passive gas extraction system, in compliance with
NR 504 Wis. Adm. Code, will be placed over the waste mass,
after saturated wastes have been excavated and pl aced over
port ions of the site where wastes are not saturated. In
addition, a groundwater extraction and treatment system will
be ;nstalled, unless additional data indicates that a
groundwater extraction system is not required to comply with
State groundwater quality standards. The groundwater system
and the capping will be designed to have minima' impacts on
the surrounding wetlands.
Est'lmltld Costs: Construction ~ $5,ZOO,000
(A1ternlt1v8 7A) Operation and Maintenance. $393,800.1st 5 years;
S146,600 after 5 years
30 Year Present Worth - $8,500,000
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w-", ...
.. .... ...'
The Department concurs with the selected remedy described above and presented
iJl the Record of Decision for this site. We believe that the addition of
cont i ngency 1 anguag8 re lat 1 ng to the groundwater extract i on system is an
appropriate response to the public comments received.
.,
The state of Wisconsin wi" contribute 50% of the remedial action costs
associated with this remedy at the Stoughton City Landfi" 1f the potentially
-\ responsible parties (PRPs) do not agree to fund the remedy. This assurance 1s
; . provided on the condition that U.S. EPA will pursue all legal 4ct1on against
, the PRPs, including 1s~ance of a unilateral order and litigation of such order,
prior to expending the" Fund. '
We a.1so understand that our staff will continue to work in ctose consultation
with your staff during the remaining investig~t1ve work associated with the
delineation of groundwater contamination at the Stoughton City Landfill site,
as \\'8" as duri ng the -des i gn and construction of the remedy.
Thar,k you for your cooperation in addressing this contamination problem at the
Stoughton City Landfill site in Stoughton. If you have any questions regarding
this; matter, please contact Mr. Paul Didier, Director of the Bureau of Solid and
Haz&rdous Waste Management, at (60S) 266-1327.
51 nc:erely,
c.~"~. Secret
Wiseon epartment
COB :: R5
Resources
cc: Lyman Wible- AD/5
Linda Meyer - LC/S
Paul Didier - 5W/3
Joe Brusca - SOD
Pat McCutcheon/Mike Schmoller - SOD
Mary Pat Tyson/Mike Valentino - US EPA Region V (5HS/l1)
Mark G1esf.,dt/Su8 Bangert/Robin Schmidt ~ SW/3
, .
-------
I.
II.
III.
IV.
V.
VI.
VII.
VIII.
IZ.
Z.
ZI.
XII.
ZIII.
ZIV.
. SU1DIAJtY 01' RBJIBDIAL ALHRDTIVB SBLBCTIOB
STOUGB'IOB CITY LaJlDJ'ILL SIH
STOUGB'IOB, WISCOBSIB
..........
TABLB 01' COIl'lBftS
SIH DIIB, LOCATIO. U1) DBSCUftIOB.................. 2
SIH HISTORY U1) BJI70RCBJIBft ACTIVITIBS.............. 4
BBrORCBKBB'I HISTORY.................................. 5
COKKUB%'1'Y PARTICIPATIO............................... ,
SCOPB U1) ItOLB 01' RBJIBDIAL ACTIVITIB8................ 7
8UHKaRY 01' SITB CHaRACTBRISTICS...................... 8
8UHMARYOr SIH RISK8.................~.............. 10
RATIOBaLBJ'ORACTIOB.................................13
DOCUJOD1'lATIOB or SIGBII'ICU'l' CDBGB8. ~ . . . . . . . . . . . . . .. l'
DBSCUftIOBSOrALHRDTIVBS.........................18
8UHKaRY 01' '1'BB COKPARATIVB ADLYSI8 or ALTBJUlATIVB8.. 25
TBI SILICTIDRIKIDY.................................. 30
8TA'I1J'1'ORY DBHRK%DTIOBS SUJOIARY. . . . . . . . . . . . . . . .. . . .. 31
RB8PO~8rvBKBSS8UHMARY....................... A'1"IACBKBHT
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..
2
S1JJDmRY 01' _DIAL ALHRDIfIVB SBLBClfIO.
S~oU9h~OD City Landfill sit.
DUB COUftY, WISoo8SI.
I. SID LOCAIfIO. UD DBSCRIP'l'I08
The stoughton City Landfill Site is located in the northeast
portion of Stoughton approximately 13 miles southeast of Madison,
in Dane County, Wisconsin. (Figure 1-1.) The property containing
the landfill Site encompasses approximately 27 acres and occupies
portions of the W 1/2 of the SW 1/4 and the SW 1/4. of the NW 1/4 of
Section 4, T.5N., R.11E. Although the landfill property originally
occupied approximately 40 acres, landfilling has occurred on only
about 15 acres of the property. Since 1982, land exchanges betweep
the City and the owner of an adjacent property have modified the
original property boundaries (Figure 1-3).
Figures 1-4 and 3-2 show existing site conditions and topography,
respectively. A wetland area that existed in the southeast portion
of the current property boundary was the initial area of waste
disposal. Wetlands occur adjacent to the southeast portion of the
site, in the north portion of the Site, and west-of the site along
the Yahara River. The Yahara River is located west of the Site and
comes within approximately 400 feet of the site at its closest
distance. The 100-year flood stage near the site is 843 feet above
mean sea level. The area of. the Site in which waste disposal
practices took place is elevated with respect to the flood stage
(see Figure 3-3) . Approximately 1/8 of the site (the northeastern
section which consists of wetlands) is situated within the 100-year
floodplain of the Yahara River (see Figure 3-2 which shows lowland
area of site with respect to flood stage, i.e. ,. elevation 843 above
MSL). The nearest developed land occurs along Amundson Parkway,
the site access road to the south, where residentia~ homes have
been built. A more extensive residential area occurs approximately
1/4 mile south of the Site, where the City street grid pattern
begins. The land immediately adjacent to the southern site
boundary remains undeveloped. There is no developed land in the
vicinity of the site to the west, north or east. .
Surface water flow patterns indicate radial flow outward from the
site. Surface water runoff over most of the northern portion of
the property flows to the drainage ditch in the north-central
portion of the Site. This drainage ditch originates east of the
site and also receives flow from the wetland adjacent to the
southeast portion of the property and land east of County Highway
N. Surface water in the southwestern portion of the Site flows.
toward the drainage ditch along the southern property boundary,
-------
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APPROXIMATE SCAL£ Cft)
~ .
1000 0 1000 2000
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Ref.: USGS, 7.5- MINUTE STOUGHTON
QUADRANGLE, DANE CO., WISCONSIN
POOR QUALITY
O"-'WN: JOG
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,
..-...-------
ENaW
ENSR CONSUL 11NC AND ENGINEERING
FIGURE I-I
SITE LOCATION MAP.
STOUGHTON CITY LANDFILL
STOUGHTON, WISCONSIN
0411: 3/6/90 ~cT6885-002
1lE'ttSD: ou.."c:
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LEGEND:
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ORIGINAL PROPERTY
BOUNDARY
ORIGINAL PROPERTY
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UONITOR1NG WELL
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PRE EXISTING
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STOUGHTON CITY LANDFILL
STOUGHTON, WISCONSIN
Oft..e.: HWW OA~ 7/ !1/90 ~C: 688~-002
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3
which drains toward the wetlands adj acent to the southeastern
portions of the Site. Surface water in the south-central and
southeastern portions of the property drains directly to the
wetlands. In summary, most of the surface water drains to wetlands
east and north of the site and eventually flows to the Yahara River
via a drainage ditch. A small portion of the west-central area of
the Site drains directly into the wetlands adjacent to. the Yahara
River. (Figure 3-3). .
Surficial deposits in the vicinity of the site include ice-contact
stratified deposits and lacustrine plain sediments (Mickelson and
McCartney, 1979). Ice-contact stratified deposits generally
include significant sand and gravel deposits and land forms such as
kames and eskers. These deposits occupy higher ground within the
landfill and south of it. Lacustrine plain or glacial lake-bottom
sediments are generally composed of fine-grained silt and clay.
Some sand is present near former shorelines and stream inlets.
~ese areas are often flat, poorly drained, and show evidence of
peat accumulation. Lacustrine plain deposits occupy the southeast
portion of the current property boundary, which was initially
developed for waste disposal, and the low-lying ground adjacent to
the east, north, and west portion of the site. Lacustrine plain
_sediments are generally overlain by younger marsh deposits.
Surficial deposits in the vicinity of the Site are underlain by
glacial outwash that was deposited in the preglacial Yahara River
Valley. Approximately 150 to 250 feet of unconsolidated glacial
sediments are reported to overlie Cambrian sandstone bedrock in the
vicinity of the site (Cline 1965). These-unconsolidated sediments
consist mostly of stratified and sorted sand and gravel. Some of
the outwash in the eastern two-thirds of the county is reported by
Cline to contain boulders.
Regional groundwater flow is toward the Yahara River, which serves
as a groundwater discharge. Groundwater flow in the surficial
aquifer is radial beneath the Site. (Figure 3-6). Average aquifer
characteristics of the surficial aquifer are: 1. horizontal flow
gradient ~ 1.36E-02 ft/ft: 2. vertical flow gradient - 2.79E-02
ft/ft (upward): 3. hydraulic conductivity - 15.6 ft/day: and 4.
horizontal groundwater velocity = 0.604 ft/day. . There are
variations around the Site from location to location. For
instance, the hydraulic conductivity at monitoring well clusters 3
and 4 is approximately 20.6 ft/day, the average horizontal gradient
is 9.11E-03 ft/ft, and the average vertical gradient is virtually
zero. Along the southeastern section of the Site, at monitoring
well cluster 2, there is an upward vertical gradient of 0.13 ft/ft.
The two aquifers are hydraulically connected. Municipal Well #3 is
situated about 3000 ft west of the Site and is set in the sandstone
bedrock, as an open pipe from roughly 210 ft below ground surface
to 940 ft below ground surface.
-------
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PREEXISIING IIIOIIITOIIING W£I..L
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APPIIOXI*Tt SCALE (It)
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(DASHED WHERE APPROXIWATE)
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-------
11
4
II. SIn HIS'1'ORY
The city of stoughton purchased the original 40-acre site in July
1952, and annexed it in September 1952, when landfill operation
began at the Site. Between 1952 and 1969, the Site was operated as
an uncontrolled dump Site. During this time, refuse was usually
burned or covered by dirt. In 1969, the Site began operation as a
State-licensed landfill. In 1977, the Wisconsin Dep.rtment of
Natural Resources (WONR)- required that the Site be closed according
to state regulations. Closure activities included construction of
a trash transfer station, placement of cover material borrowed from
the northwest portion of the Site and from agricultural areas,
application of topsoil also derived from an agricultural area, and
seeding. From 1978 to 1982 only brick, rubble, and. similar
construction materials were accepted at the site while closure work
was performed. The landfill was officially closed in 1982.
Common mUnicipal waste and both dry and liquid wastes were disposed
at the. stoughton City Landfill. Dry waste included sludge
materials, empty rejected metal spray.containers (used for storing
mUlti-purpose .lubricants.), and used appliances. Some sludge
materi~ls containing 2-butanone, acetone, tetrahydrofuran, toluene,
and xylene mixtures, were disposed at the site from 1954 until
1962. During this period, the liquid wastes were commonly poured
over garbage and burned~ It was also reported that some liquid
wastes were poured down holes drilled to test auger drilling
equipment in the west-central portion of the landfill.
The Stoughton City Landfill is currently an inactive facility.
Vehicular access to the Site is controlled by a set of gates that
are kept locked at all times. In addition, snow-fencing was
installed along the southern property boundary upon initiation of
the RI. Warning signs were placed along the snow-fencing and on
signposts installed on the west, north, and east property
boundaries.
The site was placed on the National Priorities List (NPL) in June
1986. In March 1988, Uniroyal plastics, Inc. and the City of
Stoughton (the potentially Responsible Parties or PRPs) entered
into an Administrative Order by Consent ("AOC" or "the Order") with
U.s. EPA and WONR for the conduct of a Remedial Investigation and
Feasibility Study (RI/FS). ERN - North Central was originally
contracted by the PRP's to conduct all work related to the RI/FS.
ERN was replaced by ENSR Consulting and Engineering in 1990 to
complete all remaining tasks of the RI/FS.
RI field activities began in March 1989. The first round of
groundwater monitoring occurred in May. and June 1989. Routine
analyses were run for Target Compound List (TCL) inorganics and
organics as well as for non-standard volatile organics,
tetrahydrofuran (THF), trichloroflouromethane and
dichlorodiflouromethane. A second round of groundwater sampling
-------
5
occurred in May and June 1990. At that time, background surface
water and secliment samples were taken froll the wetlands east of the
site and froll the area between the Yahara River and western edge of
the Site. The results of the ax field sampling are summarized in
Table 5-1.
An ecological site assessment was conducted by U.S. EPA in May
1991. A preliminary ecological assessment was sUbsequently
prepared in July 1991. The results of that preliminary assessment
are as follows; "
The wetlands surrounding the landfill are the main points of
exposure for ecological receptors; they currently receive
leachate discharge and in the past received surface water
runoff froll the landfill. Because the Site occurs in a
relatively undeveloped area, a wide variety and number of
terrestrial and aquatic organisms may be exposed to the Site
contaminants. The wetlands and wood~ surrounding the site
provide excellent babi tat for many species of birds, mammals,
reptiles, amphibians, and invertebrates. comparison of
unfiltered surface water samples with criteria and other data
indicate potential risks to aquatic life from Site-related
contamination at SL-1 and SL-2, immediately adjacent to the
southeast part of the landfill in leachate discharge areas,
and possible risks to sediment-dwelling organisms at SL-1, SL-
2, SL-7, and SL-8." .
The preliminary report g08S on to recommend that aquatic and whole-
sediment toxicity tests and communi ty surveys be conducted to
assess the actual impact to organisms in the wetlands east of the
Site. The report also states, "Remedial actions planned or
suggested for the landfill that adequately control contaminated
groundwater release from the site should be sufficiently protective
of aquatic biota."
Feasibility Study (FS) activities began in November 1989 with the
submittal of the Alternatives Array Document. A draft FS was.
submitted on January 17, 1991. The Final FS was submitted to U. S .
EPA and WDNR in June 1991. The Final FS was placed into the Site
repository prior to the start of the public comment period.
Attached to the FS were comments provided by U.S. EPA and WDNR
which highlighted deficiencies with the document in the areas of
presentation of current site conditions, human-health risks; risks
to the environment, and rationale for remedy selection.
IIX. BIIPORCBJIB1ft' BXSTORY
U.S. EPA sent Information Request Letters pursuant to section 104
of CERCLA on August 1, 1987 to the City of stoughton, Uniroyal,
Bj oin Transfer, IKI, and City Disposal. Based on the responses and
other evidence, only Uniroyal, a generator and transporter, and the
-------
~
.T8ble 5-1 (PIlI 1 of 4)
SUlWtf OF RESUlTS Of WASTE AID
EJlVIIOIIMEMTAL MEDIA SAMPLE AMUSES
. Stoughton City LINHlLl
Stoughton, .,1 sc_tn
- WASTE (UII/Ie,)
(I.e., a MWZ, MW6) SOIL CUI/II,) GW CUIIIl)
Detected Detected Detected
CHEMICAL Freqe ...,.. Freq .... Freq ..,.e
VOLATILE ClGAlltS
BenzIN 116 Z.O.I
2-butenane
CIIlorofoMl 116 1.0.1
1,Z-dlchloroethent (ctl end trlft8) 1136 8.0
1,Z-dlchloroethene Ctrena only)
Ethyl benZIN
Toluene
XyL... (totan 3136 1-0J
DiehlorodifluorG88thene 7/4Z 16J - ZI.OJ
TrichlorofluorG88th8ne 6142 6.4.1 - 24J
Tetrltlydrofunn 6/44 27 - 660J
Tentnlvely identified c~:
DlchlorG88thene 1130 38J
SEMIVOLATILE ClGAlltS
8enzoic ecid 1136 2.0J
8enzyl aLcohol
BIIC2-ethylhe.yl)phthalate 4/6 95.1 - 600000.1 3/36 2.0;1 . "'J
Butyl benZyl phthalate . 116 230.1
al-"-butyl phthalate 1/6 39.1
D I -"-octyl phthaLate 1/6 n.l
AClNPth8M
AC:=thylIN 1/6 '"
2-..t yL napthalene 1/6 52.1
lIIapthaLene 1/6 180.1
pentadt L orophenol 1136 3.0J
Anthracene 1/6 Z10.l
8enzoCa)anthracent 315 106.1 - 480
Benzo(b)fluoranthene (coelut.. 'fI/ 4/6 120.1 - 730.1
8enzo(k)fluoranthene)
8enzoC"h,l)peryLene 4/6 ".I - 210.1
BenzoCa)pyrene 4/6 72.1 - 37'0.1
Cllrysene 4/6 ~.I - 34G.I
DibenzoCa,h)anthraclN 1/6 71.1
Fluorenthene . 4/6 53.1 - 700
Fluorene 1/6 160.1
Id8noC1,Z,3-cd)pyrene 4/6 43.1 - 180.1
Pllenanthrene 2/6 860 - 1800.1
Pyrene 2/6 61.1 - 570
Tentltlwly Identified cQllPClllldl: 112 315
Alkene Z16O.1 Z5G.I - 590.1
Carboxylic acldl 2/Z 260.1.-
PoLYlrG88tlc hydroclrbon 4310.1
Unknowt hydrocarbar8 1130 3IoOJ
Adlpete
AldoL condeNat.. 1130 2J
8enzIN derlvattw 112 170.1
III-butyl benzene IUlfOfl8I. 1130 II.J
III,N-diethyl, 1,3-..thylbln&l8lde Z/3O 18.1 - 36J
1-Cethyloay)pentene
Phosphoric acid dI,t".cf.. 112 17,610.1
Pllthllate ..tera . 1/2 4,910.1
Sul fur _lecule 1/2 450.1
Vlt_ln E
PESTlCIDES/PCIa
4,4'-000 1/6 m
-------
.4
Teble 5-1 (pefl Z of 4)
SUICAIY OF IEM T5 OF WASTE AID
ENVIIONMENTAl MEDIA SAMPLE Al5LYSES
Stoughton City Lendfi U
Stoughton, Wise_in
Sf (YIIl) SEDI...T (Yllkl) All (ppI)
Detected Detected Detected
CHEMICAL Freq '''''' Freq I.".. Freq Rant.
VOLATILi ORGANICS
lenzene
Z-butenane 119 1.0.1
CtIlorofo1"8
1,Z-dichloroethene (cia end trena)
1,Z-dlchloroethene (trena only) . 111 0.06
Ethyl b8nzene 111 O.OZ
Tol~ 1/7 0.010
Xyl.... (total) 1/7 0.01
Dichlorodlfluoraeth8W 2/16 1.5.1 - J
Trichlorofluoraethene
Tetr8hydrofur8l"l
Tentatively ldentffled c~:
Dldtloraethene
seMlWUTlLE ORGANIC$
lenzoic ecid 319 100.1 - Z800.lCb)
lenzyl alcohol '19 170.1
118CZ-ethylhexyl)phthalate 719 61.1 - 59O.I(b)
lutyl b8nzyl phthalate
GI-n-butyl phthalate
Gi-n-octyl phthalate 119 5&1
Ac8ft8Pthene
AceNPthylene
Z-..thyl napthalene
Napthalene
Pent8Chloraphenol
Anthrseene
8enzo(8)lftthrecene
lenzoCb)fluor8l"lth- ccoelut.. wi 119 64.1
lenzoCk)fluor8l"lthene)
lenzo(l,h,l)peryl-
lenzo(a)pyrene
ChryMN 119 66.1
Dib8nzoCa,h)8I"Ithrecene
Fluor8l"lthene 119 110.1.
Fluorene
ldenOC1,Z,J-cd)pyren8
phen8l"lthrene . 119 69.1
Pyrene ZJ9 72.1 - 8Z.I
Tentatively Identified c~: 119
Alk- 580.1 - 9300.1
Carboxylic eclde ,''' 54.1 ," 1 0600.1 (b)
Pol Y8~t I c hydrocarban 119 1300.1
unknOWt hydroc8"'" 119 3810.1 - 6713O.1Cb)
Adlpate 119 470.1
Aldol c0rder88t..
lenlene derivative
N-butyl b8nzene sufll....
.,.,-diethyl,1,J-..thyl b8n188ide
1-cethyloxy)pentene 119 360.1
Phosphoric ecid dertv.ttve
Phthalate ..tera
Sul fur _lec:ule 119 3,900.1
Vi t_in I 319 970.1 - 4,100.1
PESTlCIDU/PCla
4,4'-000
-------
Teble 501 (P811 3 of 4)
""T OF RESUI. TI OF WASTE All)
EIIVIIOIIMEMTAL MEDIA SAMPLE AllALTSEI
Stoughton City LIf'dfHl
Stoughton. Wisconain
- WASTE (III/kl) [11
(i.e.. a MWZ. MW6) SOIL (III/kl) [11 GW (UIIl) [I]
Detected Detected Detected
CHEMICAL Freq R... Freq R... Freq R.".e
1IICIliAllitS
Ah.i... ",5 13U
Ant I IIan'f 112 15.1f 2115 33.2J 0 33.6J
ArMftlc 6/15 1.4J 0 5.2J
larh. 3/15 352 0 391
leryll i.. 1/2 O.31J
Cldlli.. 1/2 27
Ctlrali.. 1/2 40.1 1/15 8J
Cab8lt
E 112 460J 1/15 3.6J
."..... - 5/15 873 o' 2330
Mercury 112 0.62
Mickel 2/15 19.6.1 0 20.1J
Selenl.. 1/5 7.'J
V8NdI..
~.. 1/2 35.ZOG.I 3n 68,400 0 108,552 3/15 167,000 0 115,000
...... I.. 3/7 38.400 0 39.m 3/15 79,300' 53,'00
Pot... I.. 1n 611 12115 17,200 0 156,000
.us
-------
~
TebLe 5.1 (~4 of 4)
S&IICAIY 01 IEM TI Of WAST! AID
EIIVIIONME.TAL MEDIA SAMPLE MALYSEI
Stoughton City LlndtlLL
Stoughton, WIICONfn
SW (,,-,L) [I) SEDIMEIT (lIIIkg) [I)
, Detect" Detect"
CIISUCAI. Freq lenge Freq Renge
IIIOIGAIII a
AL~I"" 6/7 162.1. 12,600
Antf..., 717 2.&1 . 7.3.1
A...."ic
'.rl~ 4/7 2M . 457
leryU h. 4"
C8CIIII ~ 1.6.1. 23.3.1
CIIr_I&II 417 6.&1. 16.5
COb8Lt . 417 5.1.1. 16.3.1
c..,. 117 33.9
Le. 4/7 15.2.1. 68.6.1 '" 17Z.1
........ 517 '192.1. 4,480 '" 746.1
Mercury
.lckeL ZI7 42.3.1. 51.2.1
SeL.ni&ll
V8NdI&ll 417 23.3.1. 54.2
Zinc 417 127.1. 327.1
CaLcl&ll 3/7 134,000. 154,000
....... I &II 217 123,000. 125,000
Sodi &II
Pot...i&ll 717 5,440. 49,100
Iron 517 5,530 . 46,6GO.I
IOTES:
.Fr~ bu8d on rullb8r of detecelON for h",..efpclw, ffeLeI
_L ieaee, _tria spike, end _trl. spike _L tcace SlllllPLe _Lyses.
S8IIPL.. not _Lyzed (IA), H8U8d" I, or b8ck,round
8811Pt.. 188re not Inch.-d In tJ\. f~ det8f'llift8tion.
Fr~ be- on r'UIIb8r of deeecttON 8bo¥e quMtteatlon
U.lts for aU SlllllPUng r0Y8. Ch8teaL.. b8McI on I.,.,..ttpttw
fteLd repLic8te, _tria spike, end _tria spike _Ucate SlllllPLe _Lyses.
.I . Indicat.. 8ft ..tt-ted Y8L~.
[I) denot.. that veL,," 188re cClllPilred to b8ck,round: onLy ello8e
In exc... of tIIIica b8ckgrCUld are preaane.. .. detectiON.
(b) denot.. cCllllll'lN'd .... aLso deeected In b8ckground SlllllPL...
-------
"-...
6
City of stoughton, the owner/operator, were issued special notice
under section 122 of CERCLA for the RI/FS. No further evidence has
been discovered which would indicate that anyone other than these
two entities snould be sent special notice letters (SNL's) for
RD/RA.
On March 29, 1988 and April 15, 1988, the Secretary of the WDHR and
Director of u.s. EPA Region V's Waste Management- Division,
respectively, signed a CERCLA 106 Administrative Order by Consent
with Uniroyal and the City of Stoughton stipulating the undertaking
of a Remedial Investigation and Feasibility Study (RX/FS) for the
purposes of determining the nature and extent of the threat to the
public health or welfare or the environment due to the release or
threatened release of hazardous substances or contaminants from the
site and to evaluate appropriate remedial action alternatives to
prevent or mitigate the migration or. release of hazardous
substances or contaminants from the site.
The signed" Order underwent a mandatory 30 day public comment period
shortly thereafter. No comments were received during publ ic
comment. and the order became effective on May 2, 1988."
IV. COIOl1JJlD:'1'Y PAR'1'ICIPA'1'IOB
Pursuant to sections 113 (k) (2) (b) (i-v) and 117 of CERCLA, the
Stoughton community has participated in the remedy selection
process, in that: " "
*
Prior to any public meeting, 'a press release was sent out to
the local media and an advertisement announcing the meeting
was placed in the Stoughton Hub courier, a local paper of
general circulation:
A public meeting ("kick-off") was" held in November 1988,
announcing the scope of the RI/FS:
*
*
The three site informatidn repositories have been kept up to
date with site documents. An administrative record
containing the RX and FS reports and other documents was
placed in a site repository at the Stoughton Public Library.
"A Proposed Plan for remedial action was released for public
comment and placed into the Administrative Record on July
12, 1991 with the 30-day.comment period ending Auqust 12,
1991. A Notice of Availability of the Proposed Plan was
published in the Stoughton Hub Courier prior" to the release
of the proposed Plan:
*
*
A public meeting was held on July 24, 1991, in the Site
proximity, at which the u.s. EPA and the WDHR presented the
proposed Plan, as well as the findings of the RI/FS to the
-------
..-,
*
communi ty and received oral comments (which are addressed in
the attached Responsiveness Summary). A transcript was kept
of the public meetinq and placed in the administrative
record and Site repositories;
The u.s. EPA has received written comments reqardinq the
Proposed Plan which are addressed in the Responsiveness
summary.
v.
SooPII AIID ROLlI 01' 1UDO!DIAL AC'l'InIJ.'IlIq
Due to the complexity of the environmental settinq and the
potential for the primary contaminant, tetrahydrofuran (THF),. to
move throuqhout the aquifer, the response action will focus on
controllinq the source of contamination (i.e., the landfill
contents), extractinq and treatinq the contaminated groundwater
unless u.S. EPA determines after further investiqation it is not
necessary to meet clean-up qoals, and protectinq the adjacent
wetlands by reducinq the leachinq of iron and other metals into
. them.
The landfilled waste is classified as a low level threat waste,
- which will be contained on Site. Treatment of the landfill
contents is inappropriate because of the size of the landfill and
the absence of known "hot spots" (i.e., areas of concentrated
hazardous substances) that repre~enta principal threat.
contaminated groundwater will be treated prior to discharqe to
the Yahara River, unless further investiqative work indicates
that qroundwater extraction and treatment will not be necessary.
The qoal of the Superfund remedy selection process is to select
remedies that are protective of human health and the environment,
that maintain protection over time, and that minimiz~untreated
waste. The Site-specific clean-up qoals for the SCL site are:
*
To minimize direct contact with the wastes;
*
To minimize the further movem~nt of contaminants to
groundwater by reducing the amount of precipitation
which infiltrates the landfill;
*
To contain the movement of contaminants in
groundwater in order to prevent contaminants
leaviriq the Site boundary;
To extract and treat groundwater to meet State water
quality discharqe limits;
the
from
*
*
To restore the qroundwater to State qroundwater quality
standards.
A total of eiqht remedial alternatives, includinq the No Action
Alternative, were developed for the final version of the FS.
-------
8
These alternatives were screened and compared to each other and
evaluated with respect to the Nine Evaluation Criteria set forth
in the NCP. The Proposed Plan presented an evaluation of nine
alternatives, which included u.s. EPA's preferred remedy. . This
decision document reflects the Agency's selected alternative
which is the preferred remedy identified in the Proposed Plan
with a contingency regarding the groundwater component of the
remedy (see Section IX of this ROD). .
V%.
S1DIImRY or SXTB CDRAC'1'BIUS'fXCS
The boundaries of the landfill were defined using geophysical
surveys and. information obtained from a review of historical
aerial photographs. The south boundary was modified based on
drilling performed later in the RI. Figure 1-4 shows the
landfill boundary defined as part of the RI. . An estimated
218,000 cubic yards of waste are in place ~t the landfill. .
A variety of VOCs were measured in the soil gas survey conducted
across the landfill. Dichlorodifluoromethane was detected at
greatest concentrations and was most widely distributed .across
the landfill. Other VOCs, including trans-l,2-dichloroethene,
trichloroethene, toluene, tetrahydrofuran, benzene, and total
xylenes, were also detected. Many of these consti tuents were
concentrated in the west-central portion of the landfill;
however, high concentrations of the various compounds were
localized in other areas across the landfill. .
Refuse was apparently initially deposited in wetlands in the
southeast portion of the site, and then later in the extreme
north portion of the landfill. In the southeast area, the refuse
is saturated to a maximum thickness of approximately 5 feet. The
degree of refuse saturation is less in the north portion of the
site. .
The landfill was closed in 1982 according to then applicable
state regulations. Closure activities included the placement of
cover material. Cover materials encountered during well
installation and the soil gas survey were clay or silty clay;
however, a detailed cap study was not conducted as part of the
RI. In generaL, the condition of the .cover material appears to
be sound. An exception to this is along a small portion of the
east landfill boundary where animal holes exist. Some metallic
waste is visible in these animal holes.
A total of three rounds of groundwater sampling and analysis were
performed at monitoring well locations shown on Figure 1-8:
however, metals were determined only for one sampling round
(Round 1) and Target compound List (TCL) organics for two
sampling rounds (Rounds 1 and 2). All monitoring wells are
screened in sand and gravel deposits with the exception of MW-2S
-------
9
which is screened in refuse and lacustrine plain sediments (silty
and sandy clay). The presence of potential contamination in the
bedrock aquifer- was not previously evaluated as part of the RI.
Such an evaluation will take place durinq the additional work
activities.
Results of the RI indicated that qroundwater to the w~st of the
site is contaminated with tetrahydrofuan (THF) in concentrations
which exceed the state Enforcement Standard by more than one
order of maqnitude (660 p.q/l vs. 50 p.q/l). Limited samplinq and
analyses were conducted on the waste itself, and the results did
indicate the presence of polynuclear aromatic hydrocarbons
(PAR IS) and pthalates. PAR I S were found wi thin several times the
Contract Required Quantification Limit (CRQL) for a variety of
compounds. Bis(2-ethylhexyl) phthalate, (BEHP), was detected in
waste in concentrations as high as 600,000 p.g/kg. Sediments in
the eastern wetlands were found to contain elevated levels of
aluminum,. calcium and maqnesium. PAR's, phthalates, benzoic
acid, cadmium and lead were found in low concentrations in
sediment sampl.es taken from the wetlands southeast of. the site.
Tetrahydrofuran was measured at MW-3D at concentrations above the
Wisconsin enforcement standard (50 p.q/L) during all three
samplinq rounds. Tetrahydrofuran was also measured in one
samplinq round at MW-4D and MW-5S above the Wisconsin preventive
action limit (PAL) concentration (10 p.q/L). There are presently
no Federal drinkinq water standards for THF.
Trichlorofluoromethane was measured in MW-5S and MW-SD durinq all
samplinq rounds at concentrations below the Wisconsin PAL
(698 p.q/L).
Dichlorodifluoromethane was detected in MW-3D, MW-5S, and MW-5D
in concentrations from 16 p.g/L to 240 p.q/L durinq some samplinq
rounds. No Federal groundwater standards exist for
dichlorodifluoromethane. The State does have an interim
recommended PAL of 300 p.CJ/L for this compound.
Bis(2-ethylhexy1)phthalate was' measured during some sampling
rounds at MW-3D and MW-4D at low concentrations.
Pentachlorophenol and benzoic acid were detected at very low
concentrations in MW-6S and MW-6D, respectively, during one
samplinq round. .
Elevated concentrations of metals were detected' in various
shallow and deep monitoring wells located in all directions away
from the Site, excludinq the northeast direction. The
concentration of arsenic (5.2 p.g/L) was marginally above the PAL
of 5 p.q/L in MW-2S in one replicate sample. The highest
concentration of barium in MW-2S (293 p.g/L) was also above the
PAL of 200 p.g/L. The hydraulic gradient is vertically upward at
MW-2S and MW-2D, toward the adjacent wetlands. The concentration
-------
IWIE COIIITY
\---------------- ---.,,",\- - - - - - - _1
I JSIO+OOI. . . .
I
I . . _+00 \ . - . . . I.
i '. -, ~% . . . . ~
I .387+011 \1 ~. . \. .
\ - ..;:,;~".
I .385+00 ~ ~I. I-I~' '~~,. :: [~:4 :. . ~: .
I Iflf. . . . t)". .
--------l-~~~_NO- NO. I ~
h. ~ !H[~~/. .384+00 r- 5 .'"J C.'J ~1JE~1'" -:- F~rv ~ -;-
\~ . .'.
1 ~ 1.5 4.1 .52 ..sIND NO NO. NO \
\111 ~. .382+00 ~-IIII-IIA I ~II' [-II '-11'.
~ etn' OF' e-......
~ STI)UGHTOII '...-4 S z.J .. 6.0 I '?:,...10 .01 .
! .381+011 -10 ~O-n-IO C-10.1
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---.
10
of barium was above the PAL at MW-1S: however, this concentration
was not significantly above background. Selenium was detected
above the PAL in upqradient well MW-1S. Chromium was measured in
MW-4D below the limit of quantification but above the PAL.
Concentrations of the following constituents were above the
Wisconsin groundwater quality standards: iron (in MW-2S, MW-3S,
MW-4D, and MW-5D) and manganese (all, including the background
well). Iron was also above the standard in the private well
sampled for background purposes. These public welfare standards
are not health related, but rather are for aesthetics (e.g.,
color and fixture staining).
In the wetlands east of the Site, zinc, lead, copper and iron are
present in concentrations which exceed the state chronic
toxicity criteria for surface water.
Soil gas survey results indicated the presence of low level
volatile organics. (Figures 4-2 to 4-5).
Four VOCs were. detected at low concentrations at one. ambient air
sampling point located just north of MW-2 (see Figures 4-7 and 4~
8). These VOCs were not detected in a replicate sample at this
location. The VOCs detected and their respective concentrations
in parts per million (ppm) were: 1,2-Dichloroethene (0.06 ppm):
ethyl benzene (0.02 ppm): xylene (0.08 ppm); and toluene (0.04
ppm) . . .
Groundwater flow in the surficial aquifer is radial beneath the
site. Regional groundwater flow is west toward the Yabara River.
Groundwater flow in the bedrock aquifer is toward the west.
V%I. S1DIImRY o. JI1JDJI _1'L'I'R RISKS
Pursuant to the RCP, a baseline risk assessment was pe~formed
based on unaltered conditions at the Site, as contemplated by the
no-action alternative. The no-action alternative assumes that no
corrective action will take place and that no site use
restrictiolUl, such as fencing, zoning, and drinking water
restrictions, will be imposed. The risk assessment then
determines. actual or potential risks or toxic effects the
chemical contaminants at the Site pose under current and feasible
future land-use assUmptions. The risk assessment was approved by
u.S. EPA, in consultation with WDNR. subsequent to this approval
it was determined that the reference dose (RfD) for THF as used
in the BRA was incorrect, thereby resulting in under-calculated
site risks. The risks were subsequently recalculated using the
RfD as provided by the Environmental Criteria and Assessment
Office (ECAO), which is 0.002 mq/kq-day (versus the 0.068 mq/kq-
day RfD used in the original risk assessment). The revised risk
calculations included the following assumptions:
-------
"I
11
*
No remedial actions will be taken;
Adjacent off-Site development may occur in the future; and,
*
*
Groundwater contaminant concentrations will. not decrease
over time and the future residential scenario would involve
the consumption of contaminated water from MW-3D (where the
highest concentrations of THF were detected) over an adult
lifetime.
An assessment or the health risks associated with target
compounds identified in the RI was carried out and presented in
the risk assessment, which was submitted in final form in June
1991. Various exposure scenarios were evaluated. The-maximum
carcinogenic risks from the site (considered for both the single,
worst-case well approach and reasonable maximum risk associated
with the 95% upper confidence level [t1CL]) were within the Agency
allowable risk range. The highest total Site risk for the worst
well approach was 9.7E-05. The cumulative lifetime adult hazard
index was determined to be 1.4, of which 1.2 was as a result of
inhalation of volatile organic compounds in the air above the
Site. Because of an error in the ingestion reference dose used
for THF, the final baseline risk assessment submitted by the PRPs
underestimated potential non-carcinogenic Site risks.
The Hazard Index, an expression of non-carcinogenic toxic
effects, measures whether a person is being exposed to adverse
levels of non-carcinogens. Any hazard index value greater than
1 sugge~ts that a non-carcinogen potentially presents an
unacceptable toxic effect.
Based on the risk assumptions and routes of exposure, inqestion
of the waste, direct skin contact and inqestion of contaminants
in the surface water and sediment, direct skin contact with and
ingestion. of contaminated soil, drinking contaminated groundwater
at the landfill, and breathing air at the landfill), the
contaminants at the Stoughton City Landfill could result in
unacceptable non-carcinogenic risks such as impaired organ
function in both adults and children. .
using the correct reference dose for THF, the maximum cumulative
non-carcinogenic risk was determined by u.S. EPA to bf!- 9.5
(adul t HI), which is outside the acceptable range for non-
carcinogenic risk. These risks were based on future residential
land use scenarios within close proximity to - the site and on
future groundwater use at the site. In addition to being outside
of u.s. EPA's acceptable risk range, there are also chemical-
specific Applicable or relevant and appropriate requirement
(ARAR) exceedances at the Site.
Toxic substances may pose certain types of hazards to human
and/or animal populations. Typically, hazards to human health
-------
~
12
are expressed as carcinogenic risks and non-carcinogenic.toxic
effects~ carcinogenic risk, numerically presented as an
exponential factor (e.q., 1 X 10-6), is the increased chance a
person may have in contractinq cancer in his or her li~etime due
to exposure to a Chemical of Concern over his or her lifetime.
For example, a 1 x 10-6 risk due to a lifetime of drinkinqwater
with a Chemical of Concern in it means that the a person's chance
of contractinq cancer due to drinkinq the water over his/her
lifetime is increased by 1 in 1 million. u.s. EPA considers
risks at superfund sites in excess of 1 x 10-4 to be unaccept":ble.
Under current conditions, the qroup most likely to come into
contact with site contaminants would be individuals involved in
recreational activities in the wetlands. These individuals could
be exposed to contaminants in the surface water and sediment
throuqh direct skin contact and inqestion. The estimates of
potential ris~ were based on the followinq scenarios.. Adul ts
were assumed to be extensively exposed to the contamination for
four days annually for 30 years. Children were assumed to be
extensively exposed for seven days annually for five years.
Children are especially vulnerable to contaminated soil and water
. for several reasons. They spend more time outside, playinq, and
they are more likely to put dirty objects or finqers in their
mouths, thereby inqesting contaminated soil. .Their bodies are
still developing, and because of their lower body weight, a
smaller amount of contamination can have an effect.
Direct skin contact wi th sediment could cause a potential
increase in the risk of cancer of four potential additional cases
of cancer in every one million people exposed. Inqestinq
sediment and direct skin contact with surface water on site would
not pose an unacceptable risk to exposed individuals.
If people were to be involved in recreational activities at the
landfill, they could potentially be exposed to Site contaminants
throuqh ingestion of or direct skin contact with the waste and
contaminated soil, and breathinq contaminated air at the
landfill. However, the risks from such exposure is less than
u.s. . EPA's level of concern.
Additionally, if people were to drink the contaminated
qroundwater at the landfill, the potential increase. in the risk
of cancer posed would amount to eiqht additional cases of cancer
in every 100,000 people exposed.
The highest cancer risk at the Stouqhton City Landfill Site is
eight potential additional cases of cancer in 100,000 people
exposed ~o it. Therefore, the lifetime cancer risks associated
with the SCL Site are not considered unacceptable.
-------
.........
page 1 of 2
STOUGHTON LANDFILL
SUMMARY OF REVISED RISK CALCULATIONS STO.SUMS-1ilC1
- Adult Ch it d Li fet line
Hazard Hazard Cancer
EXPOSURE ROUTE Index Index Risk
SURFACE WATER
Ingestion NE HE NE
Dermal Exposure 4-8e-06 1.4E-05 2.6E-11
...................-...... ....--....... .-............ ...........-.
SEDIMENT
Ingesti on 4.6E-Q4 7_0E-03 7.4E-08
Dermal Exposure 1.2E-02 1.3E-01 2.2E-07.
............................",......... --............ .....---........ .......... fl ............. .....---............
WASTE
Ingestion 1.4E-06 2.1E-05 9.7E-08
Dermal Exposure 8-7E-06 5.4E-05 2.9E-07
........ ........................ -..... ....---........ ...-.......... .............
SOIL
Ingestion 2.0E-08 3_0E-07
Dermal Exposure 5.4E-07 5.6E-06
........................... .........---... ............ .............
AIR
Inhalation 1.6E+OO 4.8E+OO PRP
Inhalation 9.9E-01 3.1E+OO EPA
SUBTOTAL
========--===========a=== ============ ============ ============
Ingestion
De"..l Exposure
Inhalation
Inhalation
4.6E-Q4
1.2E-02
1.6E+OO
9.9E-01
7.0E-03
1.3E -01
4.8E+OO
3.1e+00
1.7E-07
5.1E-07
=..:a"""'..=z:aa:a==== .-=====:a:: =========-== =:a::aa=:==z:
PRP
ePA
GROUNDWATER
RME (95% UCL)
Ingestion
W
NE
SE
1-8e+oo
5.3E-02
7.7E-02
De"..l
W
Ne
se
3.oe-03
4.5e-02
1.4e-06
.. .. .... ..
.. .. .. .. .. .. .. ..
.. ... .. .. ..
MAX a INDIVIDUAL .WELLS
Ingestion
W . MW.3D
NE a IN.5S
SE a IN-2S
Dermal
waIN-3D
Ne a IN-55
se a MW-2S
9.SE+OO
5-3e-02
1.3E-01
6.2E-Q4
1.7E-03
8.5E-OS
3.0E+OO
8_6E-02
1.3E-01
4.3E-03
6.5e-02
2.0e-06
.. .. .. .. .. ..
1.SE+01
8.5E-02
2.1E-01
1.0E-03
2.7E-03
1.4e-07
7.9E-05 PRP
PRP
7.4E-05 PRP
2.0E-09 . PRP
PRP
1_3E-09 PRP
.. .. .. .. .. ..
3.9E.OS EPA
EPA
9.7E-05 EPA
========================= ============ ============ ============
7.2E-11 EPA
EPA
6.2e-11 EPA
-------
STOUGHTON LANDFILL
SUMMARY OF REVISED RISK CALCULATIONS
EXPOSURE ROUTE-
SUBTOTAL INCLUDING GW
Adul t
Hazard
Index
RME (951 UCl)
Ingestion
\I
NE
SE
1 .8E+OO
5.3E-02
7.8E-02
DeMll8i
\I
NE
SE
3.4E.03
4.5E.02
4.6E-04
1.6E+OO
Inhaiation
. . .. . . .. .. .
. .. . ..
. . .. . . .
MAX 1 INDIVIDUAl WELLS
Ingestion
\I 1 M\I-3O
NE'I M\I'SS
SE ,I M\I.2S
De....l
\I a M\I'3O
NEa M\I.5S
SE a ....,.2S
9.5E+OO
5.3E-02
1.3E-01
1.1E-03
2.2E.03
4.6E-04
9.9£-01
Inhalation
Cn1l0
Hazard
Index
3.0E+OO
9.3E-02
1.3E.01
1.1E-02
7.2E-02
7.0E-03
4.8£+00
. . .. .. . .
1.5E+01
9.2E-02
2.2£-01
8.0E-03
9.7E-03
7.0E-03
3.1E+OO
page 2 of 2
STO-SUMS.WK1
1I tet lme
Cancer
Risk
7.ge-os PRP
1.7E-07 PRP
7.4E'05 PRP
1. 7E-07 PRP
1- 7E-07 PRP
1.7E-07 PRP
PRP
....'..
3.9£-05 EPA
1.7E-07 EPA
9.7E-OS EPA
1.7E-07 EPA
1.7E-07 EPA
1.7E-07 EPA
EPA
...,,~s:aa=::: =~8'88 ======2-==-= ==--=====-===
...aT
TOTAL I NCLUD I NG G\I
RME (951 UCL)
Ing + Del'll + Inh
\I
NE
SE
3.4E+00
1 .7E+OO
1.6E+OO
. . -. .
. . . . .. .. . .
......
7.8E+00
4.9£+00
4.9£+00
......
7.9£-05 PRP
3.4E-07 PRP
7.4E-05 PRP
.......
MAX a INDIVIDUAL WELLS
Ing + Denl + Inh
\I a ""'.30 1.0E+01 1.8E+01 3.9£-05
ME a M\I.5S 1.0E+OO 3.2£+00 3.4£,07
SE a MW.2S 1.1E+OO 3.3E+OO 9.7E-OS
=+....................... ............ =+.+......~. =+=.....=...
EPA
EPA
EPA
MAX 1.... R I SIC 1.OE+01 1.8E+01 9.7E-05
......................... a._......... a.:......... a.........:.
mini- risk 1 . OE+OO 3.2E+OO 3.4£-07
-------
...
13
However, the Site does pose unacceptable non-cancerous risks, as
groundwater ingestion from monitoring well 3-D over the course of
an adult lifetime will result in a hazard index of 9.5.
For a summary of carcinogenic and non-carcinogenic Site risks,
refer to Table STO-SUMS.WK1.
nII. RA'1'IOpT.. :rea ACTIO.
During the course of an RI/FS, the U. S. EPA requires that a risk
assessm~nt be prepared according to u.s. EPA policy and
guidelines. For the SCL Site, PRP contractors prepared a
Baseline Risk Assessment under the 1988 RI/FS Administrative
Order. This risk assessment provides the Agency with a basis for
taking a respo~se action to protect human health and welfare, and
the environment. The risk assessment which incorporated
available Site information is consistent with u.S. EPA policy and
guidance, although as noted above, some revision to the risk
tables have been made by the Agency subsequent to the receipt and
approval of the document. The risk assessment and revised risk
calculations provide an estimate of the human health problems
which could potentially result if contaminated groundwater is
left untreated. As noted below, the site does pose unacceptable
non-carcinogenic risks to populat~ons which may be exposed to THF
in groundwater at the Site.
A. Risk Smmnary
Additive hazard indices exceed 1.0 in MW-3D,. due to the presence
of THF at high levels. The maximum worst-case well resulted in
a lifetime HI of 9.5. Hazard indices above 1.0 are unacceptable.
Additive excess lifetime carcinogenic risks calculated for
ingestion of contaminated groundwater were found to be within the
acceptable risk range. overall excess lifetime carcinogenic
risks for all exposure routes were determined for reasonable
worst case (i.e;., 95' upper-bound confidence interval) and single
worst-case well approaches. In each approach, cumulative Site
risks did not exceed 1 X 10-4, therefore cancer risks .are not
unacceptable. .
In addition, an ecological assessment was conducted by u.S. EPA
Region V which indicated potential adverse effects to aquatic
organisms as a result of contaminants leaching into the wetlands
adjacent to the Site's eastern border.
B. Environmental Standards Not Met at the Site
In addition to posing unacceptable risks to receptors, the
Stoughton Site does not meet certain applicable or relevant and
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14
appropriate. Federal or state environmental standards at this
time.
1. ~
The existing ~andfill cap does not meet section NR 504.07, WAC,
the current state landfill closure requirements, which have been
determined to be relevant and appropriate for this Site.' In
part, section NR 504.07, WAC requires that the cap be composed of
a 2-foot layer of compacted clay overlain by a frost-protective
soil layer.
2. Groundwater
state groundwater quality standards are exceeded in the surficial
aquifer beneath the western border of the Site. . One sample
collected. during the RI indicated a high THF concentration at MW-
3D of 660 ~g/L, compared to the state's Enforcement Standard (ES)
of 50 ~q/L, and Preventive Action Limit (PAL) of 10 ~g/L.
C. Groundwater Protection Goals
1. The National Continaencv Plan
The u.s. EPA'S groundwater protection goal has been set forth in
the NCP:
"The national goal of the remedy selection process is to
select remedies that are protective of human health and the
environment, that maintain protection over time, and that
minimize untreated waste" (Section 300.430(a)(1)(i».
The NCP details that the U. S. EPA
"expects to return usable qroundwaters to their beneficial
uses wherever practicable, within a time frame that is
reasonable.qiven the particular circumst~nces of the site.
Whenever restoration of qroundwaters is not practicable,
(the U.S.) EPA expects to prevent further migration of the
plume, prevent exposure to the contaminated qroundwater, and
evaluate further risk reduction" (Section
300.430(a)(1)(iii)(F».
Also, the NCP considers the use of insti tutional controls to
limit exposures to hazardous substances in the groundwater:
"(The U.s.) EPA expects to use institutional controls such
as water use and deed restrictions to supplement enqineering
controls as appropriate for short- and long-term manaqement
to prevent or limit exposure to hazardous substances,
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....!
15
pollutants, or contaminants.... . The use of institutional
controls shall not substitute for active response measures
as the sole remedy unless such response measures are
determined not to be practicable..." . (Section
300.430(a) (1) (iii) (D».
2. State of Wisconsin
The State's qroundwater protection qoals are set forth in Chapter
160, Wisconsin Statutes (Wis. stats.), which applies to all
qroundwater in the State. . (The State's qroundwater quality
standards are set forth in Ch. NR 140, WAC.) Chapter 160, Wis.
Stats., and Ch. NR 140, WAC, are utilized by all State aqencies
which requlate facilities, practices, or activities that may
affect qroundwater quality. consistent with these statutes, the
remedial alternatives evaluated in the FS must achieve adequate
protection of human heal th and the environment. (when
implemented), and protect the qroundwater resources of the State.
3. Clean-un Standards
The clean-up standards for qroundwater are the State Preventive
Action Limits (PALs), as set forth in ch. NR 140., Wis. Adm. Code.
Additional clean-up standards consistent with the NCP and the ROD
may be specified by U.S. BPA, in consultation with WDNR, for
other contaminants detected durinq moni torinq which lack a NR 140
numeric standard. These clean-up standards apply to those
contaminants found durinq the RI phase which exceeded PALs, as
well as any contaminants which are found to exceeel PALs durinq
qroundwater monitorinq. The PAL for THP is 10 ~q/L; the BS for
THP is 50 ~9/L.
Section HR 140.28, WAC, provides for establishing a Wisconsin
alternative concentration limit (WACL) if (1) backqround
concentrations exceed preventive action limits (PALs) and/or
enforcement standards (BSs) or (2) if it is determined that it is
not technically.or economically feasible to achieve PALs. Except
where the backqround concentration of a compound exceeds the
State enforcement standard (ES), the WACL established may not
exceed the ES for the contaminant.
The NCP provides that remediation levels should qenerally be
.attained at or beyond the edqe of the waste manaqement area when
waste is left in place. In order to determine whether or not
qroundwater extraction will be required to achieve compliance
with State NR 140 qroundwater quality standards, sample results
from all wells in the monitorinq proqram shall be considered when
evaluatinq the qroundwater quality of the Site. .
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16
D. Snmmarv
Actual or threatened releases of hazardous substances from this
site, if not addressed by implementation of the response action
selected by this Record of Decision, may present an bmiinent and
substantial endanqerment to public health, welfare, or the
environment. Therefore, based on the findinqs in the RI report
and the discussion above, a Feasibility study (FS) was performed
to focus the development of alternatives to address the risks at
the site. The FS report documents the evaluation of the
maqnitude of site risks, site-specific applicable or relevant and
appropriate requirements (ARARs), and the requirements of CERCLA
and the.NCP in the derivation of remedial alternatives for the
Stouqhton site. "
IX.
nocuxBR'l'ATIOB OP SIGBIPICAft CHANGES
The Responsiveness summary attached hereto addresses the comments
received durinq the 30 day public comment period on the Proposed
Plan. The Proposed Plan recommended excavation and consolidation
of saturated waste alonq the eastern boundary of the site,
placement of an NR 504 solid waste cap over the landfill,
qroundwater extraction, treatment and discharqe to the Yahara
River, land use restrictions and lonq-term qroundwater monitorinq
as the principal elements of the remedial action. This
alternative is listed as Alternative 7 in the Description of
Alternatives, section X. .
In response to public comments, u.s. EPA, ~n consultation with
the state, has concluded that additional investiqation of the
extent of the THF contaminant plume and further samplinq" to
determine current concentrations of THP in the qroundwater is
warranted. The information obtained from the additional
investiqations will be used to assess whether the extraction and
treatment of qroundwater as proposed in Alternative 7 is required
to meet state qroundwater quality standards and to comply with
the requirements of the NCP. Therefore, this Record of Decision
selects a response action which will consist of the following
components: NR 504 cap: qroundwater extraction and treatment to
achieve NR 140 qroundwater quality standards, unless (after
further investiqation of the extent of the contaminant plume and
the concentrations of contaminants) u.s. EPA, in consultation
with the State, determines that qroundwater extraction and
treatment is not required to meet state qroundwater quality
standards and to comply with the requirements of the NCP;
excavation of all the saturated waste and its consolidation with
the other landfill waste; continued monitorinq of the
groundwater: fencing; and land-use restrictions as far as
practicable. This alternative is identified as Alternative 7A in
section x, Description of Alternatives.
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17
Because of Site-specific circumstances at the Stoughton City
Landfill Site, the following criteria will be used to determine
whether or not qroundwater extraction and treatment is required:
, .
1. State groundwater quality standards will be presumed to be
met without groundwater extraction and treatment if, within 12
months after the effective date of this ROD, no sample from any
monitoring well indicates the attainment or exceedance of any
PAL.
2. If there is an attainment or exceedance of an ES in any
sample collected during the 12-month period after the effective
date of ,this ROD, groundwater extraction and treatment will be
initiated in compliance with a schedule to be determined-by u.S.
EPA, in consultation with the state, unless a Groundwater
Assessment Report is submitted to u.s. EPA and the state by the
PRPs wi thin 12 months after the effective date of this ROD which
evaluates all -new and pre-existing groundwater monitoring data
for the Site, and u.s. EPA, in consultation with the 'State,
determines that: (1) It is probable that no PAL will be attained
or exceeded at or beyond the edge of the NR 140 design management
zone (DMZ) or the property boundary, whichever is closer to the
waste boundary, ten (10) years after the effective date of this
ROD: and (2) In the absence of groundwater extraction and
treatment, the remedy selected, in this ROD will still be
protective of public health and the environment, taking into
account any contaminants detected in the groundwater at and
beyond the' waste boundary. If u.S. EPA determines, in
consultation with the State, that the criteria set forth in this
paragraph are met, groundwater monitoring will continue as
otherwise required, for at least thirty years after waste
'consolidation and the completion of cap construction. At any
time durinq, or at the end Qf, the first five (5) years of
groundwater monitoring, following waste consolidation and
completion of cap construction, u.s. EPA, in consultation with
the state, may require subsequent Groundwater Assessment
Report(s) which shall evaluate all monitoring results obtained to
date, to determine whether or not State groundwater quality
standards, including source control requirements, will be
complied with, within ten (10) years after the-effective date of
this ROD. If at any time u.s. EPA, in consultation with the
State, determines that, based on monitoring results, that State
qroundwater quality standards will not be met unless additional
action is taken, groundwater extraction and treatment will be
initiated and will continue until PALs are no longer attained or
exceeded at any monitoring point at or beyond the waste boundary,
or until an alternative concentration limit (ACL) established
pursuant to NR 140.28, is no lonqer attained or exceeded at any
monitoring point at or beyond the waste boundary.
3. If a PAL is attained or exceeded but there is no attainment
or exceedance of any ES within 12 months after the effective date
-------
18
of this ROD, groundwater extraction and treatment will not be
required at that time. However, groundwater monitoring will
continue as otherwise required, for a minimum of thirty (30)
years after waste consolidation and completion of cap
construction. If at any time monitoring reveals that state
groundwater quality standards will not be met within ten (10)
years after the effective date of this ROD unless additional
action is taken, groundwater extraction and treatment will be
initiated and continue until PALs are no longer attained or
exceeded at any monitoring point at or beyond the waste boundary,
or until an ACL established pursuant to KR 140.28, is no longer
attained or exceeded.
x.
DBScm:Pr:IOB 01' 1LHRDT:IVBS
The major objective of the FS and the Proposed Plan was to
evaluate remedial alternatives consistent with the goals and
objectives of CERCLA, as amended by SARA.
1. Alternative 1: No-Action
The no action includes no further activities at the site other
than a long-term program of groundwater monitoring. The
frequency of groundwater monitoring would be on a quarterly bas is
and would involve the monitoring wells installed during the
RIjFS. The groundwater samples collected would be analyzed for
the current - parameters as well as Target compound List (TCL)
volatile and semivolatile organics, Target Analyte List (TAL)
inorganics, tetrahydrOfuran, dichlorofluoromethane, and
trichlorofluoromethane. This groundwater monitoring program
would be implemented as part of all six al ternati ves on a
quarterly basis.
Under the No-Action alternative, no active response would occur,
other than long-term groundwater monitoring. The current rate of
precipitation infiltration, through the cap and landfill waste
towards the groundwater and surface water., is projected to
increase in the future as frost damage, animal burrowing, and
erosion continues. . No reduction of the rate of leaching of
contaminants to the groundwater would be provided by this
alternative, thus no risk reduction would result from this
action. Monitoring of the groundwater contuinant plume would be
implemented to monitor potentially significant impacts to the
ci ty wells and potential discharges of contaminants to the
o surface water and sediments of the Yahara River and adj acent
wetlands.
Ini tial capital costs are estimated to be $5,000. operation and
Maintenance (O&M) costs associated with sampling events and
analytical work are estimated at $134,600 annually. Therefore,
-------
19
over 30 years, this alternative would cost $2.1 million to
implement, on a net present value (NPV) basis.
2. Alternative 2: CaD ReDair and UDarade
This alternative would combine repair and upgrade of the existing
cap with fencing of the landfill boundary to restrict access, and
deed restrictions to prevent the installation of wells in the
affected area and to prohibit construction over the completed
landfill cap. Fencing, use restrictions and additional
groundwater monitoring are common elements in all of the
alternatives except the No Action alternative. These actions
would reduce the potential for exposure to soils and solid waste
in the landfill. The upgraded cap would also minimize the amount
of precipitation infiltration throughout the landfill.
Prior to repair, the cap would have to be investigated to assess
its overall condition. Soil borings to determine the thickness
and materials used in construction of the cap would be required
as part of this investigation. Any erosion, depressions, cracks,
or animal holes would also be documented.
"
After assessment of its condition, affected areas of the cap
would be repaired or upgraded to ensure that all areas where
waste disposal occurred were covered with 2 feet of compacted
clay and 6 inches of topsoil consistent with WAC NR 506.08(3)
regulations. The compacted clay would have a permeability of 1
x 10-7 em/sec. The permeability and thickness of this layer would
be equivalent to the hydraulic barrier l~yer required under
current Wisconsin regulations for solid waste facilities. The
east edge of the landfill extends to the property boundary. When
repairing the cap in this area, it will be necessary to extend
the cap past the landfill property boundary. The potential need
for a gas venting system fOllowing cap repair will also be
considered. The total area of cap repair under this alternative
is 17.6 acres. Regrading in some areas using imported fill will
be required including the relatively flat area in the vicinity of
the landfill shelter that has been identified as the primary
groundwater recharge area. The repaired cap would also be
revegetated.
Acceptable sections of the existing cap disturbed during cap
repair would also be revegetated. Fencing would be installed
around the capped area to prevent access, further minimizing the
potential for contact with soils and waste in the landfill.
Cyclone fencing, with a locking gate at the landfill entrance,
would be used. By restricting access, wear on the cap could also
be reduced.
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MULTILAYER CAP SECTION
STOUGHTON CITY LANDFILL
STOUGHTON, WISCONSIN
ORA~: R.D.JOHNSON DATE: 6/20/91
APPV1): X ~sm: X
REV.
4-8
-------
20
Groundwater use in the area would be prevented by obtaininq deed
restrictions on the use and placement of wells in the affected
area.
This alternative would cost $2.2 million for initial capital
costs, and $146,600 annually for O&M. Therefore, over 30 years,
this alternative would cost $4.4 million (NPV) to implement.
3. Alternative 3: Solid Waste CaD
This alternative would include placinq a new multilayer clay cap
over the entire landfill area. This cap would meet the
requirements for the Wisconsin NR 504.07 requlations concerninq
cover systems for solid waste disposal facilities. Reqradinq of
certain parts of the landfill usinq imported fill would be
required. The area to be capped is seen in Fiqure 4-2. No
portion of the Site situated within the flood plain would. be
capped; only the elevated waste disposal area would be capped.
After preparinq the surface, a mul tilayer clay cap would be
installed. The areal extent of the cap would be the same as for
the repaired or upqraded cap described in Alternative 2. The
cap to be installed would consist of a 0.5-foot qradinq layer, a
2-foot clay barrier. layer, a minimum 1.5-foot cover layer, and a
veqetated o. 5-foot topsoil laye~. The gradinq layer would be
constructed from the existinq cap. The clay barrier layer is
required to have a compacted permeability of 1 x 10-7 em/see or
less. (Fiqure 4-3).
A passive qas extraction system to collect .qas from beneath the
cap would be required. The need for treatment of air emissions
from this system can only be determined based on actual Site data
when the system is installed. For the purpose of this
evaluation, it is assumed that minimal air emission controls will
be required. Although this assumption may impact the cost to
operate and maintain a capping system, it is assumed that equal
cost impact will be encountered by all cappinq alternatives.
Thus. comparison of costs between alternatives is not affected and
the potential for an overinflated operating cost is avoided.
The landfill boundary would. be fenced to restrict access.
Groundwater monitorinq and use deed restrictions, as described
under Alternatives 1 and 2, respectively, would also be
implemented as part of this alternative.
This alternative would cost $3 million for initial capital costs
and $146,600 annually for O&M costs. Therefore, over 30 years,
this alternative would cost $5.2 million (NPV) to implement.
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would consist of temporary. impermeGle basins into which the
excavated refuse would be. placed. The refuse would be allowed to
drain, and the water collected for treatment in the same leachate
treatment system constructed to treat leachate from the
interceptor trenches. The dewatered refuse would' then be
relocated to the top of the landfill, and eventually capPed along
with the rest of the landfill. The total area of the landfill
requiring a cap would be reduced by excluding areas fro. which
waste was removed. ~fter completion of the solid waste
dewatering, the temporary basins would be removed.
Installation of trenches and slurry walls would be completed
after excavation of saturated wastes, with these structures being
located at the edge of the excavation farthest from the wetland~
Fill would be imported to the Site to backfill the excavated area
on the north of the landfill and to fill and slope the excavation
face in the southeast part of the landfill. The fill along the
southeastern excavation face would be graded such that the
maximum slope would be 25 percent. .
This alternative would cost $8.4 million for initial capital
costs and $351,600 annually for 0&. costs. Therefore, over 30
years, this alternative would cost $13.8 million (NPV) to .
implement. .
6.
Alternative 5: Solid Waste CaD with Groundwater PuIID and
Treat
The details of cap construction and related issues would be the
same as those discussed for. AI ternati ve 3. Gas control would be
. as described for Al ternati ve 3.
A qroundwater collection and treatment system would be a
component of this alternative. The exact number of wells, their
.locations, depths, and their pumping rates would be determined
based on treatGility studies. However, for cost estimation
purposes, it was assumed that two groundwater recovery wells
would be installed downgradient (west) of MW-3D. The wells would
collectively pump groundwater to collection piping at a rate of
approximately 75 qpm, which would carry the water to the on-Site
treatment facility. Well construction and pump installation
standards, as outlined in WAC NR 112, would be complied with. An
effluent discharge permit would have to be obtained, under the
Wisconsin Pollutant Discharge Elimination System (WPDES), if
treated groundwater is discharged off-Site. Substantive State
effluent discharge standards would have to be complied with, if
the treatment groundwater is discharged on-Site.
For cost estimate purposes, it was assumed that surface
bioloqical treatment would be used to remove tetrahydrofuran from
the groundwater. The most effective process for this Site will
be determined based on treatability studies. However, for cost
-------
23
estimation purposes, a fixed-film,
confiquration has been selected.
Treatability studies will be conducted during remedial design in
order to determine the optimum treatment process for removing THF
and other contaminants of concern from the groundwater beneath
the site. For cost estimation purposes, the FS assumed that the
THF plume would be managed via. above ground biological treatment.
plug
flow
reactor
This alternative would. cost $3.7 million for initial capital
costs, $210,800 annually for the O&M costs first five years, and
$146,600 annually thereafter. Therefore, over 30 years,. this
alternative would cost $6.2 million (NPV) to implement.
7.
Alternative 6A: solid Waste CaD with Phvsical Barrier and
Groundwater PumD and Treat
The cap would be as described in Alternative 3. The details of
construction and related issues would be the same as those
discussed for Alternative 3. Gas control would be as described
for Alternative 3. The details of installation and operation of
the groundwater interceptor/barrier trenches, and optional
relocation of saturated solid waste is as described for
Alternative 4. The details of groundwater collection and
treatment would be as described for Alternative 5.
This alternative would cost $7.7 million for initial capital
costs, $393,800 annually for the O&M costs first five years, and
$146,600 annually thereafter. Therefore, over 30 years, this
alternative wQuld cost $13.4 million (NPV) to implement.
. 8.
Alternative 6B: Solid Waste CaD with Consolidation of. Waste.
phvsical Barrier. and Groundwater Pum~ and Treat
This alternative is similar to Alternative 6A but includes the
waste excavation and consolidation option along with the
construction of a physical barrier.
This alternative would cost $9.1 million for initial capital
costs, $393,800 annually for the first five years, and $146,600
annually thereafter. Therefore, over 30 years, this alternative
would cost $14.8 million (NPV) to implement.
9.
Alternative 7: Solid Waste CaD with Consolidation of Waste
and Groundwater PumD and Treat
This is the alternative identified in the Proposed Plan as the
Agency's preferred alternative.
The cap would meet requirements of WAC NR 504 for final cover
systems for solid waste disposal facilities. The details of
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!
24
construction and related issues would be the same as those
discussed for Alternative 3. Gas control would be as described
for Alternative 3.
This al ternati ve would also consist of excavatinq wastes in
contact with qroundwater alonq the landfill's northeastern and
southeastern boundaries, and consolidation alonq the site's
western boundary. This would remove the direct contact of wastes
and qroundwater and will result in less impact to the wetlands
adjacent to the Site's eastern border.
The contaminated qroundwater plume to the west of the site would
be extracted via a system of extraction wells and treated above
qround to comply with numeric WPDES and Best Available Treatment
(BAT) requirements. The method of treatment will be determined
durinq remedial desiqn, dependinq on the results of treatability.
studies durinq desiqn. For FS cost estimate purposes, it was
assumed that surface bioloqical treatment. would be employed.
Treated qroundwater will be discharged to the Yahara River.
This alternative would cost $5.2 million for initial capital
costs, $393,800 annually for O&M costs for the first five years,
and $146,600 annually thereafter. Therefore, over 30 years, this
alternative would cost $8.5 million (HPV) to implement.
10.
Alternative 7A: Solid Waste CaD with Consolidation of Waste
and Co~~inaencv Groundwater Pumo and Treat
This alternative is a modification to Alternative 7, the
preferred alternative identified in the Proposed Plan, and this
alternative comprises the solid waste cap and waste consolidation
components of Alternative 7. As described in section IX, the
groundwater component of this remedy is subject to continqencies.
A groundwater extraction and treatment system would be required
unless the results of additional investiqation of the sand and
gravel aquifer and the bedrock aquifer indicate that NR 140
qroundwater quali ty standards will be met wi thout groundwater
extraction and treatment. This determination will be made as
described in Section IX.
The exact number of extraction wells, their locations, depths,
and their pumpinq rates will be determined by u.S. EPA, in
consultation with WDNR' based on pump tests. However, for cost
estimation proposes, it was assumed that two qroundwater
extraction wells would be installed downgradient (west) of MW-3D.
The wells would collectively pump groundwater to collection
pipinq at a rate of approximately 75 qpm, which would carry the
water to the on-Site treatment facility. Well construction and
pump installation standards, as outlined in WAC NR 112, would be
complied with. An effluent discharge permit would have to be
obtained, under the W,isconsin Pollutant Discharge Elimination
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25
System (WPDES),- if treated groundwater is discharged off-site.
Substantive state effluent discharge standards would have to be
complied with, if the treatment groundwater is discharged on-
site.
If groundwater pump and treat is required, the cost of this
alternative, in terms of capital cost, annual operating costs and
net present worth are identical to that of Alternative 7. In the
event that groundwater pump and treat is determined not to be
required, the capital cost of this alternative would be
approximately $4.5 million: annual operating costs would be
approximately $329,600 for the first five years and $146,600
thereafter: and over 30 years, the NPV would amount to $7.5
million. .
ZI.
S1DIImRY O. '!JIB COIIPARA'l'IVII ADLYSIS O. AL'l'BRD'l'IVBS
A.
'l'h. Bin. Bva1ua~ion criteria
The FS examined eight alternatives, including the No Action
alternative, and evaluated them according to technical
feasibility, environmental protection, public health protection
and institutional issues. In addition to these eight, the
Proposed Plan presented a ninth alternative which was a "hybrid"
of Alternatives 48 and 5, excluding the physical barrier. The
u.s. EPA carried forth each of. these alternatives for evaluation
in its proposed Plan. In response to public concerns over
limited groundwater contamination data, U.S. EPA, in consultation
with WD~, has proposed a tenth alternative which comprises the
components of Alternative 7, but allows for groundwater
extraction and treatment on a contingency basis, as identified in
section IX above. The alternatives were evaluated according to
the following nine criteria which are used by the u.s. EPA to
provide the rationale for the selection of the final remedial
action at a Site:
'l'JIRBSBOLD CtU'l'BRIA
1) OVerall Protection of JlUau Beal th aD4 the. BnviroDlient
addresses whether or not a remedy provides adequate protection
and describes how risks posed through each pathway are
eliminated, reduced or controlled through treatment, engineering
controls, or institutional controls.
2) Coapliuc. vith stat. ud ".d.ral Regulation. (ADa' 8)
addresses whether or not a remedy will meet all the applicable or
relevant and appropriate requirements of Federal and state
environmental statutes and/or provides grounds for invoking a
waiver.
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~J
26
PRDmltY BALAJlCDfG CJU:TBR:J:1
3) ..4uot:ioa of 'l'ozioit:y, XObilit:y, or Volua. 'l'hrouqb 'l'Z'..taeat:
is the anticipated performance of the treatment techn9loqies a
remedy may employ.
.. ) Sbon-'l'.ra .ff.ot:i v.a... 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 goals are achieved.
5) Loaq-'l'.ra .ff.ot:ivea... aa4 P8naaa8ao. refers to the ability
of a remedy to maintain reliable protection of human health and
the environment over time once clean-up goals have been met.
') Iapl_.at:aI»ili t:y is the technical and administrative
feasibility of. a remedy, including the availability of materials
and services needed to implement a particular option.
7) co.~ includes estimated capital and
maintenance costs, and net present worth costs.
operation
and
KOD:EnDfG CJU:TBJU:A
8) St:at:. Aoo.pt:aao. indicates whether, based on its review of
the RI/FS and the Proposed Plan, the state concurs, opposes, or
has no comment on the preferred alternative at the present time.
') co_uni ~y Acc8p~aao. are assessed in the Record of. Decision
following a review of the public comments received on the RI/FS
report and the Proposed Plan.
B.
C08DaratJv. ADaIv... o~~.rDatt!ll
In accordance with the KCP, the relative performance of each
alternative is evaluated using the nine criteria (Section
300.430(e)(9)(iii) as a basis for comparison. An alternative
providing the "best balance" of tradeoffs with respect to the
nine criteria is determined from this evaluation.
Each alternative was evaluated using the nine criteria. The
regulatory basis for these cri teria comes from the National
Contingency Plan and Section 121 of CERCLA (Clean-up Standards).
Section 121(b) (1) states that, "Remedial actions in which
treatment which permanently and significantly reduces the volume,
toxicity or mobility of the hazardous substances, pollutants, and
contaminants is a principal element, are to be preferred over
remedial actions not involving such treatment. The off-site
transport and disposal of hazardous substances or contaminant
materials without such treatment should be the least favored
alternative remedial action where practicable treatment
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o
27
technologies are available." Section 121 of CERCLA also requires
that the selected remedy be protective of human health and the
environment, cost effective, and use permanent solutions and
alternative treatment technologies or resource recovery
technologies to the maximum extent practicable.
Each alternative
following section:
is compared to the nine criteria
in the
1)
OVerall protectioD of BU8&D .ealth aD4 the BDViroD88Dt.
OVerall protection of human health and the environment addresses
whether. a remedy eliminates, reduces, or controls threats to
human health and to the environment. The major exposure pathways
. of concern at the Stoughton Site are the potential ingestion of
contaminated groundwater, exposure to or ingestion of
contaminated surface water and/or sediments in the Yahara River
and the wetlands adjacent to the Site, and inhalation of airborne
volatile organic contaminants. Based upon these pathways of
concern, the remedial action alternatives were evaluated on their
ability to: 1. reduce precipitation infiltration through the
landfill, which reduces the levels of contaminants leaching into
the groundwater: 2. meet clean-up standards, and: 3. reduce the
levels of hazardous substances discharging into the wetlands.
Alternatives 1 and 2 are not protective of human health and the
environment. Al ternati ves 3, 4A and 48 will prevent direct
contact with waste, and Alternatives 4A and 48 will prevent or
minimize further contact between groundwater and contaminants
along the eastern Site boundary. However, none of these
alternatives address the ground-water contamination to the west
of the .Site. Alternatives 6A, 68, 7 and 7A will prevent direct
contact with. the waste, prevent or minimize further contact
between groundwater and contaminants along the eastern Site
boundary, and will remove contaminants from groundwater to the
west of the Site, unless additional monitoring indicates that
groundwater extraction is not required. Alternative 5 will
prevent direct contact with the waste, will remove contaminants
frqm the groundwater west of the site, unless additional
monitoring indicates that groundwater extraction is not required,
but will not prevent or minimize further contact with groundwater
and contamination along the eastern boundary.
only Alternatives 6A, 6B, 7 and 7A will achieve the three
objectives stated in the above paragraph, and therefore only
Alternatives 6A, 6B, 7 and 7A are considered protective of human
heal th and the environment. Al ternati ves 1 through 5 are
therefore not protective of human health and the environment for
reasons stated in this paragraph.
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-
2)
28
Coap11ano. w1 ~Ja App110Ul. or "l8Van~ an4 a.ppropr1.~.
R8qU1r_.D1:8 (UUa).
This criterion evaluates whether an alternative meets applicable
or relevant and appropriate requirements set forth in Federal, or
more stringent State, environmental standards pertaining to
contaminants found at the Site (chemical specific), siting
requirements itself (location specific) or proposed actions at
the Site (action specific). The. Statutory Determinations
section, Section XIII, discusses all the potential ARARs for the
site. This section only notes those ARARs with which a
particular alternative does D2t comply.
Alternatives 1 and 2 fail to meet any of the chemical-specific
ARARs described in section XII, nor do they meet the NR 504.07,
WAC landfill requirements for landfill closure, which are
relevant and appropriate for this Site.
Alternative 3 would not meet NR 140 requirements pertaining to
the PAL for TBP because it would not prevent the continued
release of contaminants already present in the groundwater
detected at the waste boundary above Wisconsin groundwater
quality standards. It also fails to meet state Water Quality
criteria for wetlands, NR 103, and the"" state wetlands
antidegradation regulations, NR 105, because it does not address
the continuing leaching of metal~ from the saturated waste and
their discharge into the wetlands.
Alternative 4 would comply with the State Water Quality Standards
ARAR but not the NR 140 groundwater standards.
/ ".
Alternative
standards.
48
would
not
comply
with
NR
140
groundwater
Alternative 5 would not comply with the State Water Quality
Standards.
Alternatives 6A, 68, 7 and 7A would comply with all applicable or
relevant and appropriate requirements.
Because they are not protective of human heal th and the
environment and do not meet all ARARs, and therefore" do meet the
threshold criteria, Alternatives 1 through 5. will not be
considered for further evaluation.
3)
ae4uo~1oD of Tozioi~]', Kobi11~]', or Voluae (TIIV) 'rbrouCJJa
Tre.ta8D~.
None of the al ternati ves considered will reduce the toxicity,
mobility or volume of solid waste through treatment.
Alternatives 6A, 68, 7 and 7A will offer some reduction in the
amount of contaminants currently found in the groundwater through
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o
29
treatment. Due to the low risks posed from contact with or
ingestion of the Site waste, and because of the large volume of
wastes in place, the benefit of treating the source of the
contamination at the Site would be marginal and ,extremely
expensive.
4)
8hort-~.r.a Bff.c~iv.D....
Because wastes will be excavated and relocated, Alternatives 6A
7 and 7A would present the potential for workers to inhale or
ingest site contaminants. The additional amount of proteCtion
will have to be evaluated taking into account the disadvantages
of additional waste handling, potential ,increased exposure to
waste, and increased handling of. leachate from dewatering
excavated. wastes. site workers would be trained and required to
wear personal protection equipment during excavation activities.
Because of the proximi ty of houses to the Site, there is a
potential for' Site contaminants to become airborne and wind
blown, and inhaled by nearby residents. However, air monitoring
stations would be set up around the entire site to determine the
levels of contaminants in the air and to ensure that these levels
are safe. Placement of the cap can be completed in . less than one
year. For Alternatives 6A and 68, the installation of a physical
barrier along the southeastern and northeastern sections would
require additional time to complete. For Alternatives 6A, 68, 7
and 7A, ground-water restoration. measures west of the Site will
take many years to complete.
5)
LoDg-T8r.a Bff8C~iv8D8.. and P8r.a&D8DC8.
Alternatives 6A, 68, 7 and 7A would provide .long-term protection
. from direct contact with wastes and reduce the infiltration of
water into the landfill area. The effectiveness of these
alternatives is dependent on proper maintenance of the cap.
Alternatives 68, 7 and 7A involve the excavation and relocation
of disposed waste followed by consolidation onto the western
portion of the landfill. Because wastes currently in contact
with. groundwater along the eastern portion of the Site will be
removed, these alternatives would offer a more secure long-term
solution to this problem than Alternative 6A. The long-term
effectiveness of Alternative 6A would be dependent on the proper
maintenance of the physical barrier to be installed.
Alternatives 6A, 68, 7 and 7A would offer a permanent so,lution to
ground-water contamination by pumping contaminated groundwater
west of the site and treating it prior to discharge to the Yahara
River. .
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..A
30
')
X8pl..eatability.
construction equipment necessary for installation of the
mul tilayer cap is readily available and cap construction does not
present difficult technical or engineering challenges.
Alternatives 68, 7 and 7A would require the excavation,
relocation and consolidation of wastes. This would present some
technical difficul ty but is still technically feasible.
Al ternati ve 6A may cause impacts on the wetlands adj acent to the
site and east of the landfill as a result of construction of the
physical barrier. This physical barrier would be desiqned in
such a way as to minimize adverse impacts on the wetlands.
Surface water levels in the wetlands may be affected as a result
of the physical barrier. This situation would be evaluated and
a system would be desiqned to maintain .proper surface-water
levels. Alternatives 6A, 68, 7 and 7A would require a
ground-wa~er pumping system desiqned in such a way as to not
result in lowering of the wetlands water levels.
7)
C08t.
The cost of the selected alternative, if groundwater extraction
and treatment is required, is estimated to be $8.5 million, net
present worth, over a 30 year life. If qroundwater extraction
and treatment is not required, the 30 year NPV is $7.5 million.
When compared to Alternatives 6A and 68, the selected alternative
meets the threshold criteria at siqnificantly lower costs. For
a comparison of costs of alternatives at varying discount
factors, refer to Table "Cost Est." "
8)
stat. ACC.ptaAC8.
The State of Wisconsin concurs with the selected remedy. The
WDNR is "a signatory to the RI/FS Consent Order with the city of
stoughton and Uniroyal, and has been an active and supporting
participant in the remedial process for this Site. "
')
co_mdty A~c.pt8Dc..
The specific comments received and u.s. EPA's responses are
outlined in the Attached Responsiveness Summary.
. "
Z%%.
TJIB SBLB~D RBIIBDY
U.S. EPA and WOHR believe that Alternative 7A is the. most
appropriate solution for the SCL site because of its performance
against the nine evaluation criteria previously discussed. The
major components of the selected alternative include the
following: NR"S04 cap: groundwater extraction and treatment for
removal of the THF plume west of the landfill; unless additional
monitoring indicates that extraction is not required to achieve
compliance with state groundwater quality standards; and
-------
AL TERNA11VE 5:
Solid Waste Cap
with 5-yr. Groundwater
Pump & Treat
ALTERNATIVE 6A:
Solid Waste Cap
wllh Physical Barrier and
GW Pump & Treat (costed lor 5 yrs.)
ALTERNATIVE 68: $9.121.000 Vrs.I-5: $393.800
Solid Waste Cap wllh Vr.. 6-30: $146.600
Consolidation 01 Waste.
. Physical Barrier and
GW Pump & Treat Ccosted 101 5 yrs.)
ALTERNA11VE 7: $5.200.000 Vrs. 1- 5: $393.800
Solid Waste Cap with Vrs. 6-30: $146.600
Consolidation 01 Waste and
GW Pump & Treat Ccosted 101 5 yrs.)
ALTERNA11VE 7A 8: $4.500.000 Vrs. 1- 5: $329.600
Solid Waste Cap ~Ih . Vr.. 6-30: $148.600
Consolidation 0' Waste and .
GW Pump & Treat Contingency (nol costed)
NOTE: . Superfund program RI/FS guidance recommends that a discount rate 0' 5CMt before taxes and after Inllatlon be assumed. as shown
In the shaded column and as used by the PAPs In the FS Report. Net Present Values .hown are rounded to the nearest $1.000.
Percentages shown In Net Present Value (NPV) columns cORlpare NPV against NPV In .haded column. Alternative 7A was nol
presented In the Proposed Plan. This table Is revised from FS Report Table 7-1.
TABLE COST EST.
--
REMEDIAL ALTERNAT1VE
ALTERNA11VE 1:
No Action'
AL TERNAT1VE 2:
Cap Repair & UPGrade
ALTERNATIVE 3:
Solid Waste Cap
AL TERNA11VE 4A:
Solid Waste Cap
with Physical Barrier
ALTERNAT1VE 4B:
Solid Waste Cap
with Consolidation o' Waste
and Physical Barrier
STOUGhTCht ~ LANDFiLL
COMPARA11VE COSTS 0;: REMEDIAL ALTERNA11VES
.' .
. NET PRESENT VALUE .
OVER 3O-YR PROJECT UFE8
Cat 5'" discount rate). :,. .' .'
. ,. ;::::/: '.}.,~,()14,ooo:;
.. .',.,,;' .''; "..,:.-
$4,409,000
.. .0..
.. ss.~237,oOO .
. .','" . eM
$12,349,000
~
CAPITAL
COSTS ANNUAL OIM COSTS
$5.000 Yrs.I-3O: $134,600
$2.155.300 Vrs.1-30:
$146.600
"
NET PRESENT VALUE
OVER 3O-YR PROJECT UFE
Cat 1~ discount rate)
$1,214.000
-~:
$3.531.000
-2(M
$4,365.000
-17CMt
$10.259.000
~17'"
NET PRESENT VA~UE
OVER 3O-YR PROJECT UFE
Cat ~ discount rate)
$2.643.000
27...
$5.029.000
14...
$2,983.442 Vrs. 1-30:
$148.600
$5.857.000
1~
$13.836.000
1~
$11.723.000
-15'"
$13.813.000
QIMI
$15.300.000
11CMt
$6.9«.000 Vrs.I-3O:
$351,600
$5.321.000
-15'"
. $6.228,000
. . QIMI
,
$6,863.000
1(N.
$8.408,000 Yr.. 1-30:
$351,600
$10.026.000
-SCMI
$11.031,000 .
. eM
$11.113.000
6...
$3.696.000 Vrs. 1- 5:
Yrs. 6-30:
$210.800
$146.600
$11.440.000
-8'"
$1~,
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31
excavation and consolidation of saturated wastes. Alternative 7A
also includes the installation of a fence around the Site: the
placement of institutional controls such as deed restr~ctions to
control future land use: and the use of lonq-term qround-water
monitorinq to determine the effectiveness of the cap and
qround-water extraction system, if required.
The selected remedy is. the final remedial alternative to be
implemented at the Stouqhton site, encompassinq all areas of
concern at the landfill. The areas of concern are considered to
be the qroundwater contaminant plume located to the west of the
landfill boundary and leachate qeneration alonq the eastern
boundary of the site which is impactinq the adjacent wetlands
area. The landfill itself is considered to be a low-level, lonq-
term threat to human health and the environment, primarily as a
further source of qroundwater contamination.
The alternative recommended by u.S. EPA, after consultation with
WDNR, for the Stouqhton City Landfill Site, Alternative 7A,
provides the best balance with respect to the nine criteria.
Based on information available at this time, u.S. EPA believes
that the recommended remedy is protective of human health and the
environment, complies with ARAR's and is cost effective.
The evaluation of the other alternatives found that:
XIII.
*
Alternatives 1, 2, 3, 4A, 48 and 5 are not protective
of human health and the environment and/or do not
comply with ARARs.
Alternative 6A will address the potential for further
qround-water contamination east of the Site by placinq
a physical barrier along the southeast and northeast
sections of the landfill, thereby limitinq the movement
of contaminants away from the Site. This alternative
would also effectively limit contaminant movement
throuqh the waste and treat qround-water contamination
west of the Site. However, the barrier would pose
maintenance problems and would not offer the lonq-term
reliability that Alternatives 7 and 7A would offer.
*
*
Alternative 68 would address qround-water contamination
problems and would. also effectively limit contamination
movement throuqh the waste. However, this Al ternati ve
is more costly than the recommended Alternative.
1.
Protection of Human Health and the Bnvironment
STATUTORY DBTBRMINATIONS SUMKARY
The selected remedy will prevent direct contact with wastes and
reduce contaminant levels in the aquifer to the State's NR 140
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32
standards. In addition, the selected remedy will provide for
protection of the eastern wetlands by preventing or mitigating
further effects from leachate generation from wastes situated in
the water table in the southeastern and northeastern sections of
the site.
2.
AttaiDa8nt of ARAB.
The selected remedy will attain all Federal and state applicable
or relevant and appropriate requirements as presented in the FS
and in this Record of Decision. In addition, the selected remedy
will attain all Federal and state "To Be Considered" requirements
as described in the FS and in this Record of Decision.
1.
Chemical soecific ARARs
Chemical specific ARARsregulate the release to the environment
of specific substances having certain chemical characteristics.
These requirements generally set health or risk-based
concentration limits or discharge limitations after treatment in
various environmental media for specific hazardous substances.
The selected remedy would achieve compliance with the following
chemical specific ARARs related to groundwater, surface water
discharges and ambient air quality at the site.
A.
Federal
1. Maximum containment Levels (MCLs) and Maximum Containment
Level Goals (MCLGs), 40 CFR Part 141. These are enforcable
drinking water standards established by U.$. EPA under the Safe
Drinking Water Act (SDWA), 40 U.S.C. S 300 et. seq. MCLs are
applicable when the water will be provided directly to 25 Qr more
people or will be supplied to 15 or more service connections and
are to be measured at the tap. Because the groundwater at the
SCL Site. is not currently a source of drinking water, MCLs are
not applicable. At the stoughton site, MCLs and MCLGs are
relevant and appropriate, since the sand and gravel aquifer is a
Class IIa aquifer (a potential drinking water source) which could..
potentially be impacted by the contaminant plume. MCLGs are
relevant and appropriate when the standard is set at a -level
greater than zero (for non-carcinogens). The point of compliance
for MCLs and MCLGs is at the boundary of the landfilled-wastes.
At the SCL site no MCLs or above-zero MCLGs are currently
exceeded. .
2. Ambient Water Quality criteria, 40 CFR Part 131, developed
under the Clean Water Act (CWA), 33 U.S.C. S 1251 et. seq. for
protection of human health and aquatic life. The Federal Ambient
Water Quality criteria (AWQC) are non-enforceable guidelines that
set pollutant concentration limits to protect surface waters that
are applicable to point source discharges, - such as from
industrial or municipal wastewater streams. At the SCL Site, the
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33
treated qroundwater will be discharqed to the Yahara River.
CERCLA section 121(d) (1) requires the u.s. EPA to consider
whether AWQC would be relevant and appropriate under the
circumstances of a release or threatened release, dependinq on
the desiqnated or potential use of qroundwater or surface water,
the environmental media affected, and upon the latest information
available. At a Superfund site, the Federal AWQC would not be
applicable since they are non-enforceable quidelines, but they
are relevant and appropriate for pretreatment requirements for
discharqe of treated water to a Publicly Operated Treatment Works
(POTW). since treated water will be discharqed to the Yahara
River, AQWC adopted for drinkinq water and AWQC for protection of
freshwater aquatic orqanisms are relevant and appropriate to the
point source discharqe of the treated water into the Yahara
River. AWQC adopted for drinkinq water and AWQC for protection
of freshwater -aquatic orqanismsare relevant and appropriate to
the discharqe of the treated qroundwater into the Yahara River.
3. National Ambient Air Quality Standards, 40 CFR Part 50. May
be applicable to air strippinq, fuqitive dust raised from
excavation, qradinq and other construction activities. Every
available precaution will be taken durinq construction to
minimize fuqitve dust emissions. In the event-air strippinq is
used to treat qroundwater prior to discharqe to the Yahara River,
any emissions for which there are standards will be monitored.
However, it is not anticipated that air strippinq of THF will
release any-listed contaminents.
B.
state
1. The State of Wisconsin is authorized to administer the
implementation of the Federal SDWA. The state has also
promulqateci qrounciwater quality standards in Ch. NR 140, WAC,
which the WDNR is consistently app1yinq to all facilities,
practices, and activities which are requlated by the WDNR and
which may affect qroundwater quality in the state. Chapter 160,
Wis. stat.., directs the WDNR to take action to prevent the
continuinq release of contaminants at levels exceedinq standards
at the point of standards application. Groundwater quality
-standards established pursuant to Ch. NR 140, WAC, include
preventive action limits (PALs), enforcement standards - (ESs),
and/or (Wisconsin) alternative concentration limits (WACLs).
Because state PALs are more strinqent than federal MCLs, and
because there are no MCLs . for certain of the contaminents of
concern, notably THF, state PALs are applicable to the stouqhton
site as qroundwater clean-up standards.
Consistent with the exemption criteria of section NR 140.28, WAC,
a Wisconsin alternative concentration limit (WACL) may be
established to replace the preventive action limit (PAL), as the
qroundwater clean-up standard if it is determined that it is not
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34
technically and economically' feasible to achieve the PAL for a
specific substance. Except where the background concentration of
a compound exceeds the enforcement standard (ES) consistent with
the criteria in section NR 140.28(4)(8), the WACL. that is
established may not exceed the ES for that compound.
The implementation of the selected remedy at the stoughton site
will be in compliance with Ch. NR 140, WAC, in that preventive
action limits (PALs) will be met at and beyond the edge of the
waste management area unless WACLs are established pursuant to
the criteria in section NR 140.28, WAC, in which case the WACLs
will be met.
2. section 303 of the CWA requires the state to promulqa.te state
water quality standards for surface water bodies, based on the
designated uses of the surface water bodies. CERC.LA remedial
actions involving surface water bodies must. ensure that
applicable or relevant and appropriate state water quality
standards are met. The state has promulgated Wisconsin Water
Quality criteria (WWQC) under Ch. NR 105, WAC, based on the
Federal AWQC developed by u.s. EPA. The Yahara River is
designated as a warm water sport fish community under Ch. NR 105,
WAC. The warm water sport fish WQC are therefore applicable to
the maintenance of surface water quality impacted by the
discharge of treated groundwater from the site.
3. The state is authorized to implement the National Pollutant
Discharge Eiimination System (NPDES) program. For discharge of
treated water, the applicable or relevant and appropriate
requirements are dependent on the point of discharge. The
substantive requirements of a Wisconsin Pollutant. Discharge
Elimination syst.. (WPDES) permit, under Ch. NR 220, WAC, would
be applied to the discharge of. the treated water into the Yahara
River, since the discharge point is considered to be on-site.
Subject to the approval of the u.s. EPA, effluent limits for
surface water discharge will be established by the WDNR. Ch. NR
220, WAC requires that the effluent limits be based on the
application of best available treatment technology (BAT) prior to
discharge.
, A determination of technical or economic
infeasibility may be made, no earlier than five years after
operation of the ground water extraction. system begins, if it
becomes apparent that the contaminant level has ceased to decline.
over time and is remaining constant at a statistically significant
level above the PAL (or any WACL established due to high background
concentrations) in a discrete portion of the area of attainment, as
verified by multiple monitoring wells. ..
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2.
Action SDecific ARARs
Action specific ARARs are technology or - activity based
requirements or limitations on actions taken with respect to
hazardous waste. They indicate how a selected remedy must be
achieved.
A.
Federal
1. Clean Water Act section 404 prohibits the deposit of dredqed
or fill material in wetlands without a permit. The substantive
prohibition will be observed durinq site activities pertaininq to
remedy implementation.
" 2. Executive Order 11990 - Protection" of Wetlands, is an
applicable requirement to protect aqainst the loss or deqradation
of wetlands. -The selected remedy will comply with this Order in
the design of the qroundwater extraction system, when excavatinq
the saturated waste, when constructinq the cap and when designinq
or implementinq any other component of the remedy.
3. RCRA Subtitle C. RCRA is not applicable at the Site because
the jurisdictional requirement that the facility have treated,
stored or disposed of RCRA hazardous waste after July 26, 1982 is
not met. Disposal ceased at the SCL in 1972 and the landfill was
closed in 1980. However, certain of the RCRA requirements
pertaininq to the cap and future monitorinq of the facili~y are
relevant and appropriate.
4. RCRA Subtitle D. The cap proposed for the Stouqhton site
consists of a qradinq layer, a minimum 2-foot compacted clay
layer, "a qravel drainaqe layer, a frost protective soil-layer,
and a minimum 6-inch topsoil layer. These components satisfy the
requirements of RCRA Subtitle D and also section HR 504.07, WAC,
which is the relevant and appropriate requirement for this site.
(See discussion of State action specific ARARs below).
5. If air strippinq is chosen as the method for treatinq
extracted qroundwater prior to discharqe, that activity, as well
as the handlinq of contaminated soil durinq. excavation,
consolidation of waste and cap construction could cause air
emissions in exceedances of Clean Air Act standards. The design
of the selected remedy will either reduce such emissions to
acceptable levels or treat them to comply with standards.
B.
State
1. Ch. NR 102, WAC establishes an antideqradation policy for all
waters of the State and it establishes water quality standards
for use classifications. Chapter NR 102, WAC would be applicable
to actions that involve discharges to the Yahara River in that
discharqes must meet water quality standards.
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I
2. Ch. NR 103, WAC, establishes water quality standards for
wetlands. Ch. NR 103, WAC, would be applicable to actions that
affect wetlands. The implementation of the selected remedy will
reduce contaminated qroundwater discharqe . to the wetlands and
thus comply with the anti-deqradation provisions of Cb. NR 103,
WAC, and assure that siqnificant adverse impacts to the wetlands
will not occur in the future.
3. Chapter NR 504, WAC is not applicable to this site because
it requlates the closure of currently permitted solid waste
landfills in the state. Since the Ch. NR 504, WAC closure
requirements are sufficiently similar to the requirements for
closure. of the stouqhton site, in that a cap of sufficient
inteqrity to minimize liquid infiltration into the waste is
. necessary to retard further leachinq of contaminents into the
qroundwater, Ch. NR 504, WAC requirements are relevant for the
stouqhton site. Chapter NR 504, WAC requirements are well-
suited for the Stouqhton site due to the reduction of
precipitation infiltration and the long-term effectiveness
offered by the frost protection layer. Thus, Ch. NR 504, WAC~
the current solid waste landfill closure requirements, are also
appropriate for this site. section NR 504.07, WAC. calls for the
landfill cover to be composed of a qradinq layer, a minimum 2-
foot clay layer with a permeability of 1 x 10-7 em/s, a frost-
protective soil layer, and a minimum 6- inch topsoil layer. These
requirements will be met by the cap component of the selected
remedy.
4. The state is authorized to implement the National poilutant
Discharqe Elimination System (NPDES) proqram. For dlscharqe of
treated water, the applicable or relevant and appropriate
requirements are dependent on the point of discharqe. The
substantive requirements of a Wisconsin Pollutant Discharqe
Elimination System (WPDES) permit, under Ch. NR 220, WAC, would
be applied to the discharqe of the treated water into the Yahara
River, since the discharqe point is considered to be on-site.
Subject to .the approval of the u.S. EPA, effluent limits for
surface water discharqe will be established by the WDNR. Ch. NR
220, WAC requires that the effluent limits -be based on the
application of best available treatment technoloqy (BAT) prior to
discharqe.
\,
5. Chapter 147, Wisconsin statutes, is also applicable to
treated water to be discharqed to the Yahara River. These
requlations state that no discharge shall contain quantities of
listed pollutants qreater than that would remain after subjectinq
the water to best available technoloqy economically achievable
(BATEA) . .
u
6. Chapter NR 445, WAC requlates air emissions from treatment
technoloqies and is applicable to point source emissions from
industrial facilities. Air stripping may be used to treat
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groundwater prior to discharge. Since air strippers may emit
hazardous substances in the form of VOCa, section NR 445.04, WAC
is relevant and appropriate for' the remedy. The need for
emission control technology shall be evaluated based on
requirements of Ch. 0 445, WAC.
7. Chapter 0 27, WAC, the State Endangered and Threatened
Species Act, and Ch. 0 29, WAC, the State Fish and Game Act, are
State endangered resource laws which protect against the "taking"
or harming of endangered or threatened wildlife resources in the
area. These would be applicable to the remedial action, in that
the poisoning of endangered or threatened species by Site
contaminants could be considered by the WDNR to be a "taking."
To date, no threatened or endangered species have been found at
the Site.'
3.
Location specific ARARs
Location specific ARARs are restrictions placed on
concentration of hazardous substances or the conduct
activities solely because they are in specific locations.
the
of
A.
Federal
1. Executive Order 11988 - Protection of Flood Plains, are
applicable to the Site due to its location within the mapped 100-
year flood plain (843 feet above mean sea level) of the Yahara
River. This Order would be met by desiqning the groundwater
treatment system to be located above thi.- elevation and be
protected from erosional damage.
B.
State
1. Chapter NR 112, WAC, which requires that no drinking water
wells be located within 1200 feet of a landfill, unless a
variance is obtained from the WDO, is applicable to the Site.
3.
Co.t-Bff8ct1v8n8..
Cost-effectiveness compares the effectiveness of an alternative
in proportion to its cost of providing its, environmental
benefits. The selected remedy's long-term effectiveness and its
ability to reduce the amount of THF in the surficial aquifer was
weighed against its short-term effectiveness aspects in relation
to the remaining alternatives. In general, the selected remedy
does involve a small degree of risk to site workers and to the
community in that there would be movement and treatment of
hazardous substances during implementation in order to minimize
the long-term effects those substances would have on human health
and the environment.
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With respect to VOc emissions durinq treatment of the qroundwater
and movement of saturated wastes, effective air monitorinq would
ensure that air standards established to protect human health and
the environment are met. Emission controls may be ut~lized, if
necessary, to meet those standards. Short-term risks due to the
discharqe of treated qroundwater to the Yahara River would be
minimized by ensurinq that the treated water meets discharqe
criteria, which are established to protect human health and the
environment as well.
The selected remedy will achieve the threshold criteria by
attaininq all Federal and State ARAR's and providinq protection
to human health and the environment, and at lower costs than
Alternatives 6A and 68. '
4.
u~ili.a~ioD of PeraaDeD~ 8olu~ioD. aDd Al~erDa~ive Tre.~eD~
Teclmoloqie. or Re.ource Recovery Teclmoloqie. ~o ~he xaziaua
~eD~ prac~icable
The selected alternative will provide for a permanent solution to
the THF contaminant plume west of the Site by extractinq
contaminated qroundwater and treating it above ground. Wastes in
contact with qroundwater will be excavated and placed away from
the eastern wetlands, thereby providinqa long-term solution to
the environmental impacts to the wetlands.
5'.
PrefereDce for TreataeD~ a. a priDcipal .1"8D~
There are no identifiable hot spots in the waste for which
treatment is viable or practical. Although no test pits were
conducted durinq the RJ:, analyses of borinqs obtained durinq
monitorinq well installation do not show elevated contaminant
concentrations indicative of hot-spot disposal areas. Due to the
heteroq_neity of the waste, it is not feasible to excavate and
treat a specific portion of the landfill. ' ,
Extraction of groundwater to the west of the Site will reduce
concentrations of contaminants to levels which will meet State
qroundwater quality standards, if this component of the selected
remedy is required as described in Section IX above.
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