..
United States
Environmental Protection
Agency
OffICe 01
Emergency and
Remedial Response
EPAlRODJR08-93/070
June 1993
PB94-964408
&EPA
Superfund
Record of Decision:
Minot Landfill, NO
u . S. Environmental Pt. .
Regio0 III Hazardous W~sI;tlon Agency
8Te~hnlcallnformation Center
4 I Chestnut Stre t 9
. Philadelphia I PA 191 aih Floor .
~-~---
Hazardous Waste Collection
Information Resource Center
US EPA Region 3
Philadelphia. P A 19107
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50272.101
REPORTDOCUMENTA~ON 1" REPORT NO. 2. 3. Reclplant'. Acc88810n No.
PAGE EPA/ROD/R08-93/070
4. Thla and Subtitle 5. Raport Data
SUPERFUND RECORD OF DECISION 06/21/93
Minot Landfill, ND 6.
First Remedial Action - Final
7. Author(a) 8. Parformlng Organization Rapt. NO'
9. Parfonnlng Organization Nama and Aclclr- 10 ProJ.ct Ta.lcJWortl Unit No.
11. Contract(C) or Grant(G) No.
(C)
(G)
12. Sponaorlng Organization Name and Add..... 13. Type of Raport & Period eovar8d
U.S. Environmental Protection Agency
401 M Street, S.W. 800/800
Washington, D.C. 20460 14.
15. Supplamantary Nota.
PB94-964408
16. Abatract (Limit: 200 word.)
The 17-acre Minot Landfill site is an inactive waste facility in Minot, Ward County,
North Dakota. The site is situated approximately 2,000 feet south of the Souris River
and is bounded on the west by several expressways. Land use in the area is mixed light
industrial, residential and agricultural. From 1961 to 1971, the Minot Landfill (Cell
A) operated, and accepted municipal and industrial waste from the City of Minot, other
neighboring towns, farms, industries, and military' sites. -The exact composition of the
approximately 390,000 yd3 of waste disposed of onsite is unknown: however it is likely
that the site may have received arsenic-contaminated soil and residues and industrial
solvents. In mid-1985, the County health unit investigated the site and identified
foul odor, gas bubbles in standing water, and runoff from the waste. The State
required that the owner control the surface water drainage, repair the eroded channels,
and install a gas venting system. Although some erosion channels and depressions were
filled, and a road was constructed across the fill, the State still required additional
landscaping and a gas ventilation system. This action was not completed: therefore in
1989, the City of Minot fenced in Burial site A, constructed onsite drainage controls,
and completed cap repairs. This ROD addresses a final action for potential threats
(See Attached Page)
17. Documant Analyel. a. o..crlptora
Record of Decision - Minot Landfill, ND
First Remedial Action - Final
Contaminated Media: soil, debris, sw
Key Contaminants: VOCs (benzene, PCE, toluene), other organics (PAHS, PCB, pesticides,
phenols), metals (arsenic, chromium, lead)
b. IdantifianalOpen-Endad Tann8
c. COSATI Field/Group
18. Availability Statamant 19. Sacurlty CI... (Thla Raport) 21. No. of Pag..
None 68
20. Sacurlty CIa8a (ThIs Pagl) 22. Price
None
(SM ANSI.Z39.18)
SHlnatruet/ona 011 Reverse
OPTIONAL FORM 272 (4-77)
(Formarty NTI5-35)
Department of Commerce
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EPA/ROD/R08-93/070
Minot 'Landfill, ND
First Remedial Action - Final
Abstract (Continued)
resulting from the future mitigation of leachate and gas emissions. The primary
contaminants of concern affecting the soil debris, and surface water are VOCs, including
benzene, PCE, and toluene; other organics, including PAHs, PCBs, pesticides, and phenols;
and metals, including arsenic, chromium, and lead. '
f
The selected remedial action for this site includes scraping the soil in the vicinity of
the landfill to a depth of 3 feet and consolidating it under the landfill cap; extracting
and transporting leachate from onsite extraction wells to the city's sewer system, and
then to the municipal wastewater treatment facility; installing an active landfill gas
collection and venting system; repairing and reconstructing the landfill cap, and using a
perimeter diversion beam to provide more effective surface water control; revegetating the
cap; monitoring ground water and leachate; abandoning any wells within the limits of the
waste; and implementing institutional controls, including land and ground water use
restrictions. The estimated present worth cost for this remedial action ranges from
$1,531,500 to $2,537,800, which includes an annual O&M cost ranging from $39,700 to
$43,300. These costs reflect the differences between whether the city or another party
completes the remediation.
PERFORMANCE STANDARDS OR GOALS:
Ground water adjacent to the landfill must not exceed 10-4 to 10-5 risk range for
carcinogens or an HI=1.
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o (}
ERRATA SHEET
(November 1993)
. "
RECORD OF DECISION
OLD MINOT LANDFILL SUPERFUND SITE
MINOT, NORTH DAKOTA
Page 1. Section I. second line:
Range 85 west
is corrected to be
h
. line:
Marjorie Kermitt
is corrected to be
a",' .
"" " "~ .: ~~.
'\.
;~
~'7:~
Range 83 west
Marjorie Kermott
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."'ft'.
~
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
REGION VIII
999 18th STREET - SUITE 500
DENVER. COLORADO 80202-2466
. "
. .
~~/PJr
RECORD OF DECISION
OlD MINOT LANDFILL SUPERFUND SITE
MINOT, NORTH DAKOTA
JUNE 1993
Print~ on Reeyc/Ild P6P8'
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. 0
DECLARATION FOR THE RECORD OF DECISION
SITE NAME AND LOCATION
Old Minot Landfill
Minot, North Dakota
STATEMENT OF BASIS. AND PURPOSE
-
'Ibis decision document presents the selected remedial action for the Old Minot Landfill site, in
Minot, North Dakota, chosen in accordance with CERCLA, as amended by SARA and, to the
extent practicable, the National Contingency Plan. This decision is based on the arlminim-ative
record file for this site.
The State of North Dakota concurs with the. selected remedy.
Actual or threatened releases of hazardous substances from this site, if not addressed by
implementing the response action selected in this ROD, may present an imminent and substantial
endangennent to public health, welfare, or the environment.
DESCRIPTION OF THE 'RJOMEDY
The selected remedy addresses the potential risks identified at the site by treating leachate and
managing the discharge of leachate and landfill gases. This action incorporates removal,
treatment and containment technologies. The major components of the remedy include:
.
Institutional controls to prohibit constmction on the 1andfiU, or the use of water
beneath the JandfiJl or in the immediate.vicinity of the 1andfi1l for drinkil'lg water
pmposes.
.
Leachate extraction and treatment in the City of Minot wastewater treatment
facility. .
.
Consolidation of CODbmin~ted soil in the vicinity of leachate seeps under the cap,
and cap improvements to limit precipitation infiltration and control storm water
mnoff. .
.
Ground-water monitoring to allow detection of future releases of conbmin~nts to
the ground water. .
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.
Landfill gas collection using an active collection system and a tall stack for
dispersion venting. EP A may modify the system design to accomodate site
conditions, following installation of the leachate collection system.
STATUTORY DETERMINATIONS
The selected remedy is protective of human health and the environment, substantively complies
with Federal and State requirements that are legally applicable or reIevant and appropriate to the
remedial action, and is cost effective. - A waiver from the State standard for 1andfi1l cap
permeability is justified under the requirements of Section 121(d)(4) of CERCLA since the
combination of Jandfdl capping and leachate extriction will attain an equivalent standard of
performance through the use of another method or approach. This remedy utilizes permanent
solutions and alternative treatment (or resource recovery) technologies to the O'ulrimum extent
practicable for this site. There are no principal threats at the site. However, this remedy
satisfies the statutory preference for treatment as a principal element of the remedy through
treatment of the leachate. The size of the landfill and the fact that there are no on-site hot spots
. that represent the major sources of con~mination preclude a remedy in which coornminants
could be excavated and treated effectively. . . .
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 remedial action to
ensure that the remedy continues to provide adequate protection of human health and the
environment.
~
Ij) A / /J./J..I! C
:/n/ V ~ ~ .
W. cGraw, Acting Regional ~tfminimator
S. Environmental Protection Agency, Region vm
6/;./ 17"' ~
Date I I
~
Francis 1. Schwindt, hief
Environmental Health ection
North Dakota State Department of Health
and Consolidated Laboratories
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v
Section
1
u.
m.
IV.
V.
VI.
vu.
VID.
TABLE OF CONTENTS
~
SITE NAME AND LOCATION
.............................1
SITE HISTORY AND ENFORCEMENT ACI1VlTIES ........... 1
1. History of Opera.tion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2 History of Response Actions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
HIGIillGHI'S OF COMMUNITY PARTICIPATION... . . . . . . . . . 7
- SCOPE AND ROLE OF RESPONSE AcnON ................. 8
SITE~CTE]USTICS ................................8
1. Ground Water. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2. Surface Water. . . . . . . . . . . . . . . . . . ." . . . . . . . . . . . . . . . . . . . . . 10
3. Soil................................................ 10
4. Sediment............................................ 11
5. I.a.n.d.fill Gases. . . . . . . . . . . . . . . ! . . . . . . . . . . . . . . . . . . . . . . . . 11
SUMMARY OF SITE RISKS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
1. Contaminants and Media of Concern. . . . . . . . . . . . . . . ~ . . . . . . . 12
2. Exposure.Assessment ..................................12
3. Toxicity .Assessment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4. Risk Characterization. . . . . . . ~ . . . . . . . . . . . . . . . . . . . . . . . . . . 15
. .. . . .
. . .
DESCRIYI10N OF ALTERNATIVEs .-.. ~..................... 21
1. .Alternative 1 - No Action. . . . . . . . . . . . . . . . . . .'. . . . . . . . '. . . . 21
2 .Alternative 2 - Capping, Consolidation of Contaminated .
Soil Under the Cap, Leachate Extraction and Treatment,
Passive Landfill Gas Collection, and Institutional
Conttals ............................................ 21
3. Alternative 3 - Capping. Consolidation of Contamina.ted
Soil Under the Cap, Leachate Extraction and Treatment,
. Active Landfill Gas Collection With Tall Stack Venting.
and Institutional Controls. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
SUMMARY OF COMPARATIVE ANALYSIS OF
ALTERNATIVES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
1. Overall Protection of Human Health and the EnviroIPI1ent
......24
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Section
IX.
x.
Awendix
A
B.
TABLE OF COmENTS
(Continued)
~
2. Complian.ce with. ~ .......................... '. . . . . 25.
3. Long-Term Effectiveness and Permanence. . . . . . . . . . . . . . . , , , , 26
4. Reduction of Toxicity, Mobility, and Volume Through
Trea~eDt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
. s. Short-Term Effectiveness. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
6. Im.plementability'....................................... 28
7. Cost................................. ~ . . . . . . . . . . . . . 29
8. State AcceptaJ1c:e .'. . . . . . . . . . . . . . . . . . . . . . . . . . -8 . . . . . . . . . . 31
9. Community AcceptaJ1ce . . . . . , . , . . . . . . . , , , . . . . , , . . . . . 0, . , , 31
SEI..EcrED REMEDY, . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . , . 31
1. Leachate Extraction and Trea~ent in the City of Minot
Wastewater Trea~ent Plant. . . . . . . . . . . . , . . . . . . . . . . . . , , , , 32
2. I..a.ndfill Gas Collection. . . . . . . . . . . . . '. . . . . . . . . . . . . . . . . . . . 32
3. Consolidation of Contaminated Soil Under the Cap . . . . . . . . . . . . 32 .
4. I..a.ndfill Capping. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
S. Institutional Controls. . .. . . . . . . . . . . . . . . , . . . . . . . . . . . . . . , . 3S
6. Monitoring.......................................... 35 .
STATUTORY DETERMINATIONS. . . . . . . .. . . . . . .0. . . . . . . . . . . 38
1. Protection of Human Health and the Environment. . . . . . . . . . . . 38
2. Compliance with ARARs ....,........... ~ . . . . . . . . . . . . . . 39
3. Cost Effectiveness. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
4. Utilization of Permanent Solutions and Alternative.
Trea~ent Technologies (or Resource Recovery Technologies)
to the Maximum Extent Practicable.. . . . . . . . . . . . . . . . . . . . . ~ . 41
5. Preference for Treatment as a Principal Element. . . . . . . . . . . . . . 41
bG
AR.ARs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .". . . . . . . . . . . . AI
A-t. Pertinent Federal ARARs and Compliance Analysis
A-2. Documentation of State ARARs
RESPONSIVENESS SUMMARY.. . .. . . . . .. .. . . .. . . . . . . . , . .. Bl
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. "
Fi~re
1.
2.
3.
Table
1.
2.
3.
4.
5.
6.
TABLE OF CONTENTS
(Continued)
liST OF FIGURES
~
General Location Map of the City of Minot,
North Dakota. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Site Location Relative to the City of Minot,
North Dakota. ...... .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
- Old Minot Lan~ Minot, North Dakota
......................4
liST OF TABLES
~
Oassification of Chemicals of Concern for
Health Risk Assessment. . . . . . . . . . . . . . . . . . . . . ~ . . . . . . . . . . . . . 13
Quantitative Toxicity Parameters and Carcinogenic
Potency Factors for Chemicals of Concern. . . . . . . . . . . . . . . . . . . . . . 16
Noncarcinogenic Risks - Summary Table' . . . . . . . . . . . . . . . . . . . . . . . 19
Excess Ufetime Carcinogenic Risks - Snmmary Table. . . . . . . .. . . . . 20
Cost Suynmary for the Selected Remedy (City of Minot
Implementation) ........ ~ . . ~ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Cost Summary for the Selected Remedy (Private Party
Implementa.tion) ......................................... 34
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OLD MINOT LANDFILL
RECORD OF DECISION
I.
SITE NAME AND LOCATION
The' Old Minot Landfill Superfund site is a closed waste disposal facility located in Section
27, Township 155 North, Range 8S West, approximately one mile southwest of downtown
Minot, in Ward County, North Dakota. The site is situated approximately 2,000 feet south
of the Souris River and is located to the east of the intersection of the Burdick Expressway
and the combined U.S. Highways 2 and 52 Bypass. Although the site was originally thought
to cover 45 acres, including tWo burial cells (A and B), the fill area that received municipal
and industrial waste actually covers approximately 17 acres. Land use in the vicinity of the
site is light industrial and residential, with areas southwest of the site used for agriculture.
Figure 1 shows the site location relative to the state of North Dakota, and Figure 2 shows
the location of the landfill with respect to the City of Minot. A map of the site, including
burial cells A and B, is presented in Figure 3.
0::
II.
SITE HISTORY AND ENFORCEMENT AcrMTIES
.. '
1.
HistoJy of Operation
The Old Minot Landfill (Cell A) operated from 1961 to approximately October 1971. The
facility was sited under the direction of the Minot City Council within a natural coulee
southwest of, Minot, North Dakota. The landfill was operated by Allen Long,
Superintendent of Sanitation for the City of Minot, during the approximate 1o-year site life,
and accepted municipal and industrial waste from the surrounding area. An estimated 75
tons/day of waste were placed in the landfill during its operation.
Although the property has had several owners since 1961, the past owners were not involved
in the facility's operation. Jenner, Ine., purchased much of the property in 1975 for
development. Since then the land has been returned to the former owner, Marjorie Kermitt.
One of the parcels is currently owned by Farstad Oil, Ine.
The exact composition of wastes disposed at the landfill is not known. Discussions with past.
landfill operators indicated refuse was received from the City of Minot, other neighboring
towns, farms, industries, and military. sites.
The site may have also received arsenic-contaminated soil and residues. It is also likely that
common solvents used in a variety of local industrial applications would have been disposed
of in the landfill. Records and interviews with past employees indicate that wastes were not
segregated during the filling operation. All waste was disposed of as it arrived. The refuse
1
,,' .
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--
M
o
.
50
tOO MII.tS
I
SOURCE: PE'iiY.JOHN (196;)
Figure 1. General Lccation Map of the City of Minot, North Dakota
2
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U.S.G.S. I: 100.000' MINOT. N.C.
Figure 2.
Site Locatlan Relative ta the CIty af Minot, Narth Dakata
3
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.
11
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FIGURE 3
Old Minot landfill
Minot, North Dakota
(I) Buildings
. Leachate Extraction Well
.
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LIMIT OF
hURlED WASTE
(BASED ON TEST
PIT AND SOIL
BORING DATA)
. ~~...
. .'
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was covered daily with clay-rich soU; therefore, it is probable that numerous cells of refuSe
exist.
The landfill was closed in the fall of 1971. Since the waste was placed at the base of a
coulee, the ridges m~1ring up the valley walls were used as a final cover. The refuse was
covered with about three feet of clayey material from the valley walls and seeded.
Subsequent recreational activities and traffic on the covered area increased erosion across
the site. . .
An area (Cell B) northwest of Cell A w.as landfilled in the late 19605 with constrUction
debris. The Gty of Minot bas indicated that the disposal activities in Cell B were unrelated
. to the Gty's municipal solid waste landfill operations.
2.
Histo~- of R~nse Actions
In mid-1985, the First District Health Unit (FDHU) of Ward County received a complaint
of gas bubbles escaping from the surface of the site. Upon inspection of the site, the Chief
Sanitarian of the FDHU contacted the North Dakota State Department of Health
(NDSDH), Environmental Health Section, about his observations of foul odors, gas bubbles
in standing water, and water drainage from waste.... The NDSDH Division of Hazardous
Waste Management and Special Studies responded to the request from the FDOO with a
site inspection to confirm earlier observations.
The NDSDH arranged a meeting at the site in late summer with the Gty of Minot and the
landowners. The NDSDH requested the landowner (represented by Odell-Wentz &
Associates) to control surface water drainage, to repair eroded channels, and to install a gas
venting system. The NDSDH contacted the Region vm U.S. Environmental Protection
Agency (EP A) office to discuss the investigative approach for the site. EP A proposed to
conduct an initial study of the site utilizing an EP A contraCtor under the provisions of the
Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA).
A pre1imin~'Y assessment/site inspection (P A/SI) was conducted at the Old Minot Landfill
in early June 1986. Four borings were completed and four monitoring wells were installed
at the landfill by Water Supply, Ine., under the direction of the Ecology & Environment
Field Investigation Team (E&E FlT), an EPA contractor. One well was located upgradient
of the landfill to provide background water quality data, and two wells were located
downgradient. One boring was advanced through refuse to characterize the waste. SoU
sampl~ ground-water samples, and sediment and surface water samples were collected for
analysis. Air samples were also collected for analysis in the summer of 1986.
In September 1986, the NDSDH conducted a site inspection to see if the corrective
measures requested in 1985 had been implemented. The site inspection noted that some
erosional channels and depressions had been filled across the site and a road (18th Street
Southwest) had been constrUcted across the southern edge of the fill. However, more
s
.
p~ ..."
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landscaping and a gas ventilation system were once again requested of the landowner. As
a result, Deucalion Research, In~ proposed to the NDSDH to construct a gas recovery
system at the site and utilize the gas as an energy source. .
The results of the sampling by E&E m became available in late September 1986. Soil
boring and sediment samples detected several organic chemicals. Metals were also detected.
at concentrations slightly above background sample concentrations. Off-site sediment
samples ~en near the Souris River and city water intake. detected a number of aromatic
hydrocarbons as well as fluoranthene and pyrene. Samples of water in an on-site ditch near .
a leachate seep contained organics and metals. Analysis of ground-water samples collected
on-site detected several organics and metals. Air monitoring detected traceS of organics at
variable concentrations dependent upon wind velocity and direction.
The EP A developed a preliminary hazard ranking system (HRS) score for the site in late
1986. The final ranking was completed in September 1987 and indicated that the Old Minot
Landfill should be proposed for placement on the National Priority list (NPL) for cleanup.
. This information was released in June 1988.
The Old Minot Landfill was placed on the NPL in March 1989. During June and July 1989,
the City of Minot conducted interviews with the past operators of the landfill to help
determine waste types and PRPs. The EP A Region vm Emergency Response Branch
requested the U.S. Bureau of Reclamation (USBR) to prepare a background report of
existing conditions. Recommendations were made by the USBR to conttol surface erosio~
. to investigate ground-water conditions more thoroughly, and to determine the cause of
leakage around gas recovery test wells installed earlier by Deucalion. As a result, the City
of Minot fenced burial site A, constructed drainage conttoIs, and completed cap repairs.
In the latter part of 1989, the City of Minot proposed to take the lead in the program and
retained SEC Donohue as a consultant for services at the Old Minot Landfill Superfund site.
Identification and notifications of other PRPs by the EP A continued. The City of Minot ..
received a draft Consent Order and. Work Plan for the removal action (fence installatio~
surface runoff diversio~ and erosion conttol devices). A fence was installed to confine
~SS to site A, ~ per negotiations with the EP A. The EP A contacted over 100 PRPs for
information. As a result, the City of Minot conducted a meeting in January 1990 to inform
those people and/or businesses about the Superfund process..
In March 1990, SEC Donohue split samples with the EPA during a confirmation sampling
. of three of four wells sampled in 1986 by E&E. The contaminant levels in the refuse well
were similar to those detected by E&E in the m report of June 1986.
In Aprlll990, Science Applications International Corporation (SAlC) prepared a snmmary
report on available data at the Old Minot landfill Superfund site in response to a request
by the EP A. Results of the review concluded that the release of haZardous constiments to
either ground water or surface water at the Old Minot Landfill Superfund site did not pose
6
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an immediate threat. Recommendations we're made to funher define the ground-water
system and waste boundaries, and that monitoring of ground water, surface water, and air
should continue.
The City of Minot, as well as other identified PRPs, received a Statement of Work (SOW)
and draft Administrative Order on Consent (Consent Order) in June 1990 that was prepared
by the EP A for implementing a Remedial Investigation/Feasibility Study (RIfFS). During
negotiations on the draft Consent Order, the City of Minot indicated that it was unwilling
to reimburse EP A for oversight costs and would not agree to be subject to conditions under
which it could be assessed stipulated penalties. Consequently, a Unilateral Administrative
Order (UAO) and Statement of Work was issued by EP A on September 28, 1990. The City
of Minot, which was identified as a PRP in the UAO, agreed to comply with the order
(letter dated October 10, 1990) and retained SEC Donohue to prepare the RI/FS Work
Plan. The RI-was completed and the RI report was submitted in February 1992. The FS
was 5n~li7.ed and submitted to EP A in November 1992.
It should be noted that RI and FS efforts were limited to Cell A (see Figure 3) and did not
include Cell B. 'Ibis decision was made based on available analytical data which suggested
that there was no substantial evidence linking environmental cont~mination of surface water,
ground water, or sediment with Cell B. Unlike the investigations performed within the Cell
A area, drilling operations in the Cell B area encountered no domestic or industtial wastes.
According to the records, construction debris was the only material encountered throughout
the Cell B drilling efforts. EP A will continue to evaluate additional information, as it
becomes available, and may'initiate further investigations of Cell B if warranted.
IlL
HIGHLIGHTS OF COMMUNITY PARTICIPATION
A public meeting was held, concerning the landfill, by the City of Minot in January of 1990.
An EP A community involvement coordinator conducted interviews of Minot citizens during
the week of September 2S, 1990. A Community Relations Plan for the Old Minot Landfill
site was fin~1i7.ed in November 1991. This document lists contacts and interested parties
throughout government and the local community. It also establishes communication
. pathways to ensure timely dissemination of pertinent information. As a result of community
interviews conducted in 1990, it was determined that there was a general.concern that EP A
was spending the community's money on unnecessary activities. In response to this concern,
EP A chose to limit future Cotnmunity Relations Program actions to the minimum
. permissible under CERaA and EP A policy. .
The Baseline .Risk Assessment was released in April 1992, and the RI was completed and
released to the public in May 1992. An information update concerning human health risks
associated with the site that were detailed in the risk assessment report was provided in the
Minot Daily News on July 17, 1992. The FS was finalized in early December 1992, and a
Proposed Plan for the landfill was mailed to interested parties in late December 1992. All
7
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....
.:
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~.;;. ~~. ,>: .Pt:i~"'~:';a:q
. .
of these documents were made available in both the admini!;trative record and the
information repository maintained at the Minot Public Library.
A public comment period was held from January 4, 1993 to February 2, 1993, and a public
meeting was held at 7:00 p.m. on January 19, 1993 at the Minot Oty Hall to present the
results of the RIfFS and the preferred alternative. During the public meeting a proposed
alternative developed by the City of Minot was also presented by a Minot City Council
member. 'Substantial modifications of the original proposal were addressed in subsequent
letters from the City of Minot. The plan was formally adopted by the Minot Oty Council
as Resolution # 1306, and several letters of support for the proposal were received from area
businesses and orvni72tions. EP A also received several requests from the community for
a 30-day extension to the public comment period and extended the deadline to March 4,
1993. Comments which were received by EPA prior to the end of the public comment
period, including those expressed verbally at the public meeting, are addressed in the
Responsiveness Snmm;Jry which is attached, as Appendix B, to this Record of Decision.
IV.
SCOPE AND ROLE OF RESPONSE ACTION
This ROD addresses the potential threats to humans and the environment resulting from
future migration of leachate and gas emissions from the Old Minot Landfill Superfund site.
Specific elements that the response action will address in eliminating or mitigating the
potential threats include: (1) the landfill must have a cap that is adequate to prevent direct
contact by receptors with the waste or leachate; (2) the leachate levels in the landfill must
be m~naged to prevent leachate seeps through the cap and to reduce the potential for
leachate migration from the landfill in the ground water; (3) the landfill gas must be
controlled to reduce pressures in the landfill that can dama.ge the landfill cap and can
increase the potential for leachate migration; (4) institutional controls must be implemented
to prohibit any human activity on the landfill that would expose receptors to refuse or
leachate, or that would damage the containment system; and (5) ground water in the vicinity
of the landfill must be sampled and analyzed at regular intervals to demonstrate that the
selected remedy is effective.
v.
SITE CHARAcrERlSTICS
The Old Minot , 2nnfill is located in a deep ravine which has small, ancillary rills and gullies
entering a larger coulee. An estimated 390,000 cubic yards (195,000 tons) of waste were
buried within the landfill (SEC Donohue, 1992). Soils at the landfill site are composed
primarily of impervious clayey and silty clay materials that contain numerous discontinuous
sand and silty-sand lenses of varying thickness. Ground water at the Old Minot Landfill is
present at shallow depths within the glacial till deposits. The saturated till is not used as
a source of potable water due to very low yields and its poor natural water quality.
However, the ground water within the till may provide limited recharge to other aquifer
8
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systems. It is estimated that 18.6 million gallons of leachate are present within the saturated
landfill wastes.
Available data on the contaminants present in the environmental media in and around the
Old Minot Landfill include the analysis of ground-water, surface-water, soil, sediment, and
air samples collected during the P A/51 and RI sampling programs. In general, contaminSTIts
were deteCted in leachate in the landfill, in landfill gas, in soilloc:ated near a leachate seep,
in surface water and sediment at the site, and in ground water located immediately adjacent
to the landfill. Both the physic:al and chemic:al data indicate that significant ground-water
contamination has not migrated from the site. . 'However, uncontrolled releases of
contaminants at low levels does occur from leachate seeps and landfill gas releases. The
following general conclusions were drawn from the previous studies:
. The -t'efuse is covered by a soil cap that is a minim11T1) of 3 feet thic:k. .
. Leachate seeps exist and have adversely impacted soils at the seeps. These
leachate seeps may become more pronounced if no action is taken. However, to
date, natural surface water bodies have not been impacted by the landfill
contamination.
. Site physic:al conditions have limited ground-water contamination and subsurface
gas migration to the immediate vicinity of the landfill.
. Gas emissions from the landfill release volatile organic compounds to the
, atmosphere. '
Specific contamin9nts detected in individual media and the distribution of contaminants at
the Old Minot landfill Superfund site are briefly discussed below:
1.
Ground Water
Investigations of ground-water contaminant migration concluded that contaminant release
to ground water beyond the landfill perimeter, and its potential effect on receptors located
downgradient, was minimal. Ground-water and leachate sampling indicated that significant
concentrations of contaminat'lts were only present in areas in direct. contact with the
, saturated waste.
Con~minants detected in ground water and leachate include: trans 1,2-dichloroethene and
vinyl chloride at concentrations up to 1400 and 49 micrograms per liter (I£g/I), respectively;
benzene, toluene, ethylbenzene, and xylene (BTEX) ranging in maYimum concentration from
23 to 180 I£g/1; phthalates; and elevated concentrations of metals such as bari~ chromium,
cobalt, copper, nickel, and zinc:. Trichloroethene (TCE) and tetrachloroethane (PCA) were
also detected in about 30% of the ground-water samples. '
I(). ~~ ~ ..
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., .
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, "
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Aroc1or 1254 was detected at a concentration of 2.6 IJ,g/1 in a composited sample obtained
from the leachate wells within the landfill. However, since no PCBs or pesticides were
detected in any of the ground-water samples collected from monitoring wells, it appears that
Arodor 1254 is not migrating from the satUrated refuse.
2.
Surface Water
Cont~m;n~nts were also detected in surface water (localized ponding) at the landfill.
Phenolic compounds constitute the largest class of cont~m;nants identified in surface water.
With a maximum concentration of almost 7,600 IJ,g/~ bis(2-ethylhexyl)phthalate was detected
the most often, followed by benzoic acid at an average concentration of 8,500 IJ,g/L Other
phenolics identified in surface-water samples include: 4-mcthylpheno~ di-n-butylpbth~l~te,
diethylphtb~late, di-n-octylphthalate, and benzyl alcohoL More than half of the samples
tested positive for phthalate esters.
Acetone was the principal solvent detected in surface-water samples, and exhibited a
maximum concentration of 2,700 IJ,g/l. Solvents such as: 2-butanone (270 IJ,g/l), 2-hcxanone
(10 I£g/I), and 4-methyl-2-pentanone, (56 I£g/I) were also detected in one surface-water
sample. In gene~ BTEX compounds were not prevalent in surface-water samples, but
toluene was detected in nearly one-half the samples at a J!1~Yimum concentration of 128
IJ,g/l. .
Toxic metals such as arsenic, chromium, lead, and nickel were detected in a few surface-
water samples at concentrations elevated above background levels. Other metals detected
in surface water inc1~de low levels of mercury, cobalt, silver, barium, copper, vanadium, and
zinc. .
3.
.sml
Three soil boring samples and four surficial soil samples were analyzed for the presence of
organic and inorganic contaminants at the Old Minot Landfill. The highest concentration
of cont~m;n~nts was detected in a sample collected near a leachate seep.
Acetone was detected in two samples, and the highest concentration (1200 micrograms per
kilogram (lJ,gfkg» was from a subsurface soil sample collected at the landfill. Phthalate
esters were detected in nearly one-half of the soil samples and include: bis(2-
ethylhexyl)phthalate, butylbenzylphtbalate, di-n-butylphthalate, and diethylphthalate at
m~Yimum concentrations ranging from 240 to 550 IJ,g/kg. Other phenolics detected in soil
samples were phenol and benzoic acid .
Soil cores were also analyzed for inorganic cont~min~nts and were found to contain such
toxic metals as arsenic, chromium, lead, and nickeL The concentrations of these metals
'were at levels slightly above background. Other metals that were identified are: barium,
cobalt, copper, vanadium. and zinc. .
10
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4.
Sediment
Sediment samples were collected from six locations in and around the landfill site. As with
surface-water and soil data, contaminant concentrations decrease significantly with distance
from the sit~ and phenolic compounds were identified consistently in a majority of the
sediment samples. Phthalate esters detected in sediment included: bis(2-
ethylhexyl)phthala~ di-n-butylphthalate, and diethylphthalate at m~nrimum concentrations
ranging from 85 to 590 "g/kg. Phenol (maYimum concentration of 540 "gfkg) was detected
in 50 percent of the samples.
Polycyclic aromatic hydrocarbons (PAHs) were also detected in several on-site and
downstream sediment samples. Carcinogenic P AHs identified in sediment include:
beDZO[a]pyren~ indeno[l,2,3-cd]pyren~ benz[a]anthracene, bicyclic naphtha1en~ and
tricyclic phenanthrene at maYimum concentrations ranging from 100 to 330 "g/kg.
Toxic metals such as chromium and lead were detected in all of the samples analyzed, but
the highest concentrations were observed in the soil core sample used for background values
(8,700 and 17,000 "g/kg, respectively). Other metals detected include: barium. copper,
nickel, vanadi~ and zinc. In general, inorganic contaminant concentrations in on-site and
. downstream sediment samples were generally below or essentially the same as background
concentrations established from soil core data. .
5.
T andfill Gases
Ambient and on-site air sampling at the Old Minot Landfill indicated the presence of
volatile organic contaminants in landfill gases. During the 1986 air monitoring study,
methylene chloride, l,l,l-trichloroethane, benzene, toluene, tetrachloroethene, and acetone
were detected in air samples at Concentrations above background levels. Tbe air monitoring
results indicated that volatile compounds are being released from the landfill at detectable
levels even during periods of strong and gusty winds. However, these results cannot be
considered as average annual concentrations due to the extremely short sampling period.
, . '
During the RI field effort, volatile organic contaminants belonging to the halogenated
aliphatics and the benzene and related compounds classes were detected' in landfill gas
samples. Halogenated aliphatic compounds such as cis-.l,2-dichloroethene and vinyl chloride
were 'detected in all the samples. Vinyl chIorid~ a known human carcinogen, was detected
at an elevated concentration of 13,000 parts per billion (PPb) in one landfill gas sample and
dichlorodifluoromethane was dete~ed in four out of five gas samples at a maYimum
concentration of 3,400 ppb.
BTEX . compounds were also detected in most of the landfill gas samples. Toluene was
detected in all the samples at a maximum concentration of 6,600 ppb. Maximum
concentrations of xylen~ etbylbenzene, and benzene in landfill gas were 5,800, 2,800, and
440 ppb, respectively. One sample also indicated the presence of chlorobenzene at a
11
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<,
concenttation of 1,600 ppb. Other aromatic compounds detected in landfill gas include
1,3,5-trimethylbenzene and 1,2,4-trimethylbenzene.
. 0
VI.
SUMMARY OF SITE RISKS
CERCLA mandates that EP A protect human health and the environment from current and
potential future exposures to hazardous substances at the Old Minot Landfill. Therefore,
a Baseline Risk Assessment (EP A, 1992) was prepared for the site to evaluate potential
human health risks associated with the site in the absence of any remedial action. The
results of the risk assessment were used to make decisions about remedial action
alternatives. Specific objectives included: docUment the magnituc;le and primary causes of
risk at the site, provide a basis for comparing potential health impacts associated with
remedial alternatives, and provide consistency in evaluating public health threats at
Superfund sites. '
1.
Contaminants and Media of Concern
The selection of chemicals of concern (COCS) for the Old Minot Landfill Superfund site was
based on several factors such as regulatory criteria and standards for contaminant chemicals;
intrinsic carcinogenic, reproductive, and developmental hazards of identified chemicals; and
the environmental mobility, persistence, and prevalence of contaminants in the sampled
media.
The COCS identified at the Old Minot Landfill may be classified on the basis of their
structural characteristics as: solvents; benzene and benzene-related compounds; halogenated
aliphatics; phenol and phenol-related compounds; polycyclic aromatic hydrocarbons (P AHs);
and inorganic compounds. Table 1 identifies the specific compounds included for the
various types of COCS. Contamin~ted media that were quantitatively evaluated in the risk
assessment are: ground water (including leachate), surface water, soil, sediment, and landfill
gases.
2.
~osure Assessment'
Residential, commercial, recreational, and agricultural areas are currently located in the
vicinity of the landfill, and nearly a quarter (8,000) of Minot's populati9n lies within a one-
mile radius of the site. Since the latter pan of 1989, burial cell A of the landfill has been
encloSed with a chain-link fence and, consequently, public access to the site is presently
restticted Future land use for the areas adjacent to the landfill is expected to be
commercial and light industtial (SAlC, 1990). Potentially exposed receptors who were
evaluated in the Baseline Risk Assessment are: (1) adult residents and occupational
workers who live or work at or in the vicinity of the site, and (2) active children between
the ages of 3 to 12 years who live. or play in the vicinity of the site.
12
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Table 1
CLASSIFICATION OF CHEMICALS OF CONCERN FOR HEALTH RISK
ASSESSMENT
Old Minot Landfill, Minot, North Dakota
BENZENE AND COMPOUNDS
Ren~e
Toluene
HALOGENATED ALlPBA'I1CS
BromomethaDc
Bromodicbloromethanc
t-1,2-Dicbloroetbcne
INORGANICS
ArseDic
Barium
Chromium
Copper
Cobalt
PHENOL AND COMPOUNDS
Bcazoic acid
Bis(2-ethylhcxyl)phthalate
Butylbcnzylphthlllllllt~
Di-D-butylphthalatc
Bcaz[a]anthracene
Bcnzo{a]pyreac
IDdcDo[1,2,3-cd]pyrCDC
POLYCYCUC AROMATIC
HYDROCARBONS..
SOLVENTS
OTHERS
AcctODC
Aroclor 1254
Methylene c:h1oridc
Tctrac:blorocthcDC .
VlDyi chloride
. ~.:~;!".,~.
Lead
. Nickel
Vanadium
Zinc
DicthyiphthaWc
Di-D-oc:tyIphthaWC
4-Mcthylphenol
Phenol
2-MethyiDaphth.a1cDe
Naphthllll....c
PhcDaDtbreDe
.CI~"if;cabOli of chemicals of CODc:cm is based OD chemical struc:tural features. This methOd was considered
D~~ in order to identify overall health risks associated with the nature 311d extent of various chemical
classes. .
.. Only the .polycydic aroIDabc: hydroc:arboas With a sjgDific:ant carcinogenic potency were selected for risk
as~C$ft'lCDt as Beazo(a]pyreDC equivaleac:e.. .
13
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. Q
Reasonable maximum exposure (RME) and most likely exposure (MlE) scenarios for
various environmental media have been estimated for the residential and working
populations of adults and residential population of children under both current and potential
. future land-use conditions. RME exposure assumptions were based on the 90th percentile
. upper-bound confidence limit of the arithmetic mean concentration, and MlE exposure
assumptions were derived from the 50th percentile median-bound confidence limits. The
RME is the highest exposure that could reasonably be expected to occur at a site. MLE risk
estimates were calculated from mean concentrations of contaminants, and in instances where
. only a single data point was available, the risk estimate calculated was used to assess both
RME and MLE exposure scenarios. Carcinogenic and noncarcinogenic risk estimates were
calculated for the following RME and MLE scenarios: .
. Exposure to ground water used as a potable water source and incidental 'dermal
eiposure to ground water while showering.
. Incidental ingestion of surface water and dermal exposure to surface water while
swimming or wading in onsite ponds.
. Incidental ingestion and dermal contact with contaminated soil.
. Exposure by incidental dermal contact with sediment while swimming or wading
in onsite ponds.
. Exposure to chemical vapors in landfill gases, soil, and surface water.
3.
Toxici\}' Assessment
Toxicological effects from chemical contaminants are diverse and complex. In order to
estimate the potential adverse . health effects due to. exposure to hazardous chemicals, the
EP A has provided guidelines for quantitative estimation of carcinogenic and
noncarcinogenic risks for virtually all hazardous che~cals detected at the landfill.
Cancer potency factors (CPFs) have been developed by EPA's Carcinogenic Assessment
Group for estimating excess lifetime cancer risks associated with exposure to potentially
carcinogenic chemicals.' CPFs, which are expressed in units of (mg/kg-dayyl, are multiplied
by the estimated intake of a potential carcinogen, in mg/kg-day, to provide an upper-bound
estimate of the excess lifetime cancer risk associated with exposure at that intake leveL The
term "upper bound" reflects a conservative estimate of the risks calculated from the CPF. .
Use of this approach makes underestimation of the actual ~cer risk highly unlikely.
Cancer potency factors are derived from the results of human epidemiological studies or
chronic anima1 bioassays to which anima1-to-human extrapolation and uncertainty factors
have been applied. Oral and inhalation exposure route CPFs for chemicals of concern are .
presented in Table 2.
14
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Reference doses (RIDs) have been developed by EP A for indicating the potential for
adverse health effects from exposure to chemicals exhibiting noncarcinogenic effects. RIDs,
which are expressed in units of mg/kg-day, are estimates of lifetime (assumed to be 70
years) daily exposure levels for hl1mAn~ including sensitive individuals. Estimated intakes .
. of chemicals from environmental media can be compared to the RID. RIDs are derived
from human epidemiological studies or animAl studies to which uncertainty factors have
been applied (e.g., to account for the use of AnimAl data to predict effects on h1iman~).
. These uncertainty factors help ensure that the RIDs will not underestimate the potential for
adverse noncarcinogenic effects to occur. Oral and inhalation exposure route RIDs for
chemicals of concern are presented in, Table 2. .
4.
Risk Characterization
'Ibis section integrates results from the exposure and toxicity assessments in order to
quantitatively estimate the potential risks associated with exposure scenarios that have been
developed for the Old Minot Landfill. Since no complete exposure pathways were identified
for current site use conditioDS, current risk is estimated to be insignificant. However, land-
use changes in the future and/or contAminAnt migration from the landfill to offsite areas
would create the potential for currently incomplete pathways to become complete with
associated exposure and risk. Therefore, the results of the risk assessment for both adults
and children are based on potential future exposure scenariOs.
Baseline (no action) exposure and risk calculations were performed for all the exposure
scenarios. Quantitative methods were used to derive human health risks that could result
from chronic exposure to chemicals of concern. Uncertainties with risk estimates could arise
from limitations of the site characterization studies and analytical data base. In addition,
there are inherent uncertainties in developing the exposure assumptions associated with the
hypothetical future land-use scenario, and uncertainty is also associated with the
extrapolation meth()d for estimating cancer risk. Although there are uncertainties in the
final quantitative risk estimates, conservative assumptions were used to ensure a sufficient
degree of human health protection. .
Potential health risks to bl1mAn~ are expressed in two ways: non-carcinogenic and
carcinogenic. Noncarcinogenic risks are calculated by assuming that there is a dose below
which no adverse health effects will occur. Potential concern for non-carcinogenic effects
of a single medium is expressed as the hazard quotient (HQ). This value is used to generate
the hazard index (HI) by adding the HQs for all contAminAnts within a medium or across
all media to which a given population may reasonably be exposed The HI provides a useful
reference point for gauging the potential significance of multiple contAminant exposures
within a single medium or across media. A hazard index of 1.0 or greater suggests that
some caution should be exercised, but does not mean that adverse effects will re5U:lt from
exposure.
15
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TAILE 2
QUANTITATIVE TOXICITY PARAMeTERS ANO CARCINOGENIC POTENCY FACTORS FOR CHEMICALS OF CCNCERN .
. 0 Old Minot Landfill, Minot, Nortt! Daltota.
Oral Carcinogenic Imaletion
CHEMICAL Cl.ASSES Oral RfD Inhalation afD Potency Factor Carcinogenic Reference
OF CONCERN (DIg/kg/day) (DIg/kg/day) (DIg/kg/day)-1 . Potency Factor
(a) (DIg/kg/day,-1
SOLVEIITS
Acetone 1.0E-01 NA NA NA a, c
2-Buc- 5.0E-02 NA NA NA a, b
2-Huanone . NA NA NA NA. a, b
Methylene ClIloride - 6.0E-02 6.0E-02 7.50E-03 7.50E-03 a, c, k
4-Metllyl-2-pentanone 5.0E-02 2.0E-02 NA NA a
HALOGENATED ALJPHATICS
Bt'Cllalletllane NA NA NA NA b, c
Bromaaicllloromethane 2.0E-02 NA 1.30E-01 1.30£-01 a, c
t-1,2-0icllloroetftene 2.0£-02 NA 9.10E-02 9.10£-02 a
1,1-0icllloraprocane NA NA 6.8OE-02 6.80£-02 a, j
Tetracllloroethene 1.0E-02 NA 5.10E-02 3.30E-03 a
1,1,1-Tricllloroethane 9.0E-02 NA NA NA a
B£NZENE & COMPQJNDS
Benzene NA NA 2.90£-01 2.90£-01 a, c
E tllylbenzene 1.0E-01 NA NA NA a
Toluene 3.0E-01 3.0E-01 NA NA a
Xylene (toUl) 2.0£+00 7.0e-01 NA NA a, e
PHENOL & COMPOUNDS
Benzoic acid 4.0£+00 NA NA NA a
Phenol 6.0E-01 NA NA NA a
4 -Metllyll*leno l 5.0E-02 NA NA NA. a, b
Bfs(2-etllylhexyl)phthalate 2.0E-02 2.0e-02 1.1oOE-02 1.IoOE-02 a, c
Butylbenzylphthalate 2.0E-01 NA NA NA a, b
Df-n-butyll*lthalate 1.0E-01 1.0£-01 NA NA a, b
Dfethylphthalate 8.0e-.01 NA NA NA a, b
DI-n-occyll*lthalate 2.0E-02 NA NA NA a, b
POLTCYCUC ARCltATIC
HYDROCARBONS
Ac....ttlene 4.0£-01 NA NA NA a, c
Anthr~ 4.0£-01 NA 1. OOE+OO 1.00E+00 a, f
CCIntd. . .
16
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TAILE 2 (Contirud)
QUANTITATIVE TOXICITY PARAMETERS AIID CARCINOGENIC POTEMCT fACTORS fOR CHEMICALS Of CONCERN
OLd Minot LandfiLL, Minot, Nortft Dakota.
OraL Carcinogenic l11ftalation
CHEMICAL CLASSES Oral R10 Inhalation R10 Potency Factor Carcinogenic Reference
Of CONCERN (1III/k9/day) (mg/k9/day) (1III/k9/day)-' Potency Factor
(a) (1III/k9/day)-'
I8fIZ (a] antftrKerw Io.OE-01 NA 1o.50E-02 1o.50E-02 g, h
18flZo (bJ fluorantnene Io.OE-01 NA 3.IoDE-01 3.IoOE-01 g, h
lenzo(k)fluorantftene Io.OE-01 NA 2.7OE-01 2.70E-01 g, h
18flZoCaJpyrene Io.OE-01 NA 3.20E+OO 3.20E+OO g, h
Qlrys- Io.OE-01 NA 1.IoOE-02 '..IoDE-02 g, h
Dlben%ofuran. 1.0E-03 NA NA NA
Fluorantnene Io.OE-01 NA NA NA
I ndIno (1, 2,3 -cd] pyrene Io.OE-01 NA 7.9OE-01 7.90E'01 g, h
2-Metnylnapfttftalene Io.OE-01 NA NA NA
N_tftalene Io.OE-01 NA NA NA
Phenanthrene Io.OE-01 NA NA NA
Pyrerw 4.0E-01 NA 2.6OE-01 2.60£-01 g, h
I NORW I CS
Ant i IIIonY 1o.0E-0i0 NA NA NA a
Arsenic '.OE-03 1.0E-03 , .75£+00 5.00£+01 a, k
.ariUII 7.0E-02 1.0E-01o CPt NA NA a
leryll i UII 5.0E-03 5.0£-03 4.30E+OO 8.100£+00 a, It
CaaliUII 5.0E-04 5.0E-04 HA NA a
Qll'ClliUII NA HA NA NA a
QlrCllliua (VI) 5.0E-03 5.0E-03 NA 4.10£+01 a, k, l
Cobalt 5.0E-03 NA NA NA i
CQI:1P8f' 3.1£-02 3.1£-02 NA NA c, d, k
Cyanide 2.0E-02 HA HA NA a
Leed NA 1.4E-03 HA NA c, k, II
Mercury (inorganic) NA 3.0E-04 HA HA c
Methyllllercury 3.0E-04 NA NA NA a
NickeL 2.0E-02 2.0E-02 NA NA a, c, It
5 Il ver 3.0E-03 NA NA NA a
UraniUII NA NA HA NA a
V8n8CSi UII 9.0E-03 NA NA NA c
Zinc 2.DE-01 2.0E-01 NA NA c, k
ArocLor 1254 NA NA 7.7OE+OO 7. 7OE+OO a
NA . Not aY8llable: CP]. Proposed:
. auamitltive toaicity pa....ters were obtained frCIII _Lished studi.. end IRIS database
(a) Integrllted Risk Infol'l8tion Syst18 (IRIS) dacabaH (II of October 1991). .
(b) HazardC1u8 Substances Datab8nk (MSDI) on-line databUe (u of OCtober, 1991).
(c) EPA HeaL eft Effects Ass..-..t SUIIaI8ry TabLes (HEAST) FT 1989, or Superf\n2 PubLic Healtll EyaLuation M...L (1986)-
(d) R10 der;ved fl'Oll the EPA drinking w.ter standard as Listed In EPA 1989 KEAST 2nd Quarter Report.
(e) Toxicity lIIHSUI'es presented are for mixed xylenes. .
(n unit risk estt.ta b888ci on rl!!Ytsed ingestion LI'Iit risk for ICaJP fl'Cll (1) Z-stage and (g) linearized nultistage
model (Clt!8fttl Associates, 1988).
In tne abs8nc:e of quantitative toxicity par_ters for s8'l8f'8l listed CCIIIIOLI'IdS RtDs of the structural hOllDlogues
were 8dopced: (II) ICI]P reference dose: (k) an index of toxicity (like TLlo):
(t) In tlla absence of inhalation R1Os, Oral R10s or potency factors have bHn used.
(n Raference -.. for ftU8Y8lent cftrCllliua oral route.
(It) An index of toxicity (like TLlo).
Cl) Reference doses for hU8V8lent chrCllliUII by oral route.
C.) R10 for Pb is under eY8luation by EPA: an earlier R10 for lead Is listed in tnis table.
17
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.
For carCinogens it is assumed that there is no safe dose, but that the risk of cancer decreases
as the dose decreases. Excess lifetime cancer risks represent the probability, over and above
the bac:kground level, that an individual has of contracting cancer resulting from exposure
to carcinogens over a lifetime under specific: exposure conditions. In determining the need
for remedial action at Superfund sites, EP A guidance states that the total excess lifetime
cancer risks for all contaminants must fall within or below the range of one c:hance in ten
thousand (1.0E-04) to one chance in one million (1.0E-06).
. 0
In order to express estimated noncarcinogenic: hazards and excess lifetime cancer
oc:c:urrenc:es for the site, the risks for all the pathways under study were combined and are
presented by medium in Tables 3 and 4.
Table 3 provides a snmmary of the combined total hazard indices for noncarcinogenic:
effects C1.ssociated with the selected media and exposure pathways. The combined total
hazard for ground water inc:1uding the drinking and dermal exposure pathways is above
EPA's risk-based noncarcinogenic: action level of 1.0. In the case oflandfill gases, however,
only the RME combined total hazard index for adults is above the EP A criterion for
remedial action. .
Table 4 summarizes the excess lifetime cancer risks calculated for various media and
exposure pathways. The cancer risk estimates that exceed EPA's guidelines for remedial
action are highlighted in bold print.
Tbe greatest potential cancer risk for adults will be from direct inhalation of landfill gases.
Under this scenario, the probability for an adult to develop cancer above the national
average is about 1 in 100. For a c:hild, the excess cancer risk from landfill gases would be
1 in 5,000. The hypothetic:a1 risks associated with this scenario indicate that measures
should be considered for minimi7-ing construction on the landfil1 that would expose people
. to high conc:entrations of landfill gas. .
Exposure to contaminated ground water presents the second most serious potential excess
cancer risk to adults and the most serious excess cancer risk to c:hildren. The probability
that either an adult or c:hild will develop cancer in excess of background occurrences is
about 1 in 300. The hypothetical risk associated with this scenario indicates that measures
should be considered for minimi7-ing the potential for ground-water (leachate) flow from the
site.
Exposure to contaminated soils is observed to present a relatiVely lower potential cancer risk
for both adults and c:hildren. The excess cancer risk for an adult is 1 in 38,000, while the
excess cancer risk for a c:hild is about 1 in 77,000.
Direct skin contact with contaminated sediment from leacb~te seeps and onsite ponds also
presents a relatively low potential excess cancer risk for adults' as well as c:hildren. Tbe
probability that an adult will develop cancer above background occurrences is apprwimately
18
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Table 3
,
NONCARCINOGENIC RISKS. SUMMARY TABLE
Old Minot Landfill, Minot, North Dakota
Adult Children
EXPOSURE
MEDIA PATHWAYS
RME MLE RME MLE
GROUND DriDkiDg 3.2£+00 1.4E+00 3.1£+00 1.4E+00
WATER . Dermal Coatact . l.OE~ 3.1E-04 1.4E-OJ 4.3E-04
Combi- Total Hazanlbada 3.%0 1.40 3.10 1.40
SURFACE DriDkiag 3.oE-04 . 9.6E-06 . 8.2E-04 2.6E-OS
WATER Dermal ContAct (swimmiD8) 1.6E-02 S.2E-04 2.3E.02 7.1E-04
Dermal Coatact (wading) 1.2E-02 . 2.9E-04 1.6E-02 3.9E-04
~"AIAhOD 2.2E-OS 1.2E..QS 4.8E-06 2..9E-06
CombIDed Total Hazard bacia 0.03 0.00 0.Q4 0.00
SOu. TnratOD 1.1E-Ol 6.oE-02 S.7E-Ol 3.3E-Ol
Dermal Contact 4.6E-03 1.4E-03 6.QE-03 1.8E-03
Tn"..I..tioD 4.6E-14 4.2£-14 1.OE-13 3.7E-14
Combined TotaIllazanilDda 0.11 0.06 0.58 0.33
SEDIMENT Dermal Coatact (swimmiD8) 2..SE-01 1.2E-02 3.4E-01 1.6E-02
Dermal Coatact (wading) 1.9E-01 6.6E-OJ 2..SE-01 8.8E-03
Combl- Total Hazard lacla 0.44 0.02 0.59 0.03
LANDFILL
GASES W"AIAhOQ 1.9E+00 7.oE-01 4.2E-01 1.6E-01
eo..hIoed Total Hazard bacia 1.9 0.7 0.42 0.16
NODCaD~ risk estimAt~ that ex=cd EP A's risk 1cw1 for remedial ac:tioo are higJ-ligJtt,..d in bold print.
19
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" Table 4
EXCESS LIFETIME CARCINOGENIC RISKS. SUMMARY TABLE .
. , Old Minot Landfill, Minot, Nonh Dakota
Adult Children
EXPOSURE
MEDIA PATHWAYS
RME MLE RME MLE
GROUND DriakiDg 2.IE-03 1.3&43 3.3&43 1.3E-03
WATER Dermal CoDta<:t 9.7£.f11 8.SE~ L4E.f11 4.4E~
CombiDcd Total RIsks .2.IE-03 1.3&43 3.3E-03 1.3E-03
SURFACE DriDkiag 4.oE~ 4.oE-I0 L4E~ 4.7£-10
WATER Dermal CoDtact (swin""ing) 2.2E-06 2.1E-08 4.0E.f11 13E~
Dermal Contact (wadiDg) 1.6&06 l.2E.()8 2.9E.f11 7.1E-09
la"ah'hOD l.2E-09 13E-I0 2.7£-11 9.3E-12
CombiDcd Total RIsks 3.8£.4)6 3.4E~ 7.DE-ffT ZOE.os
SOn. '''vchOO %.5E-05 4.1E-06 1.3E-OS 7.%E-06
Dermal CoDtaCt LOE-06 9.oE-08 L4E-ffT 4.0E-08
',,"alahno !.SE-17 4.4E-18 3.3E-18 1.2E-18
ComblDed Total RIsks Z.6E-O! 4.2E-06 1.3E-OS 7.%E-06
SEDIMENT Dermal Coatact (swimming) 7.~ 1.DE-08 IAE006 6. 7E-08
Dermal CoDtact (wadiDg) 5.8£.4)6 6.2E-08 1.OE-06 3.6E~
CombiDed Total RIsks 1.4&G5 7.2E~ ~ 1.DE.f11
1A.NDFD..L -
GASES 1,,"al:lUOD 8.9&43 L7&m %.0&04 1.3£.04
Co-hi.. TotallUsks 8.9&43 L7E-03 %.0&04 1.3£.04
CaDccr risk ~m:lte.C.tbat exx:ccd EPA's risk Icvd for remedial adion arc higJtligJttcd in bold priDt.
20
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1 in 70,000, while the" probability that a child will d~velop cancer in excess of background
levels is less than about 1 in 400,000. .
Exposure to contSlmina.ted surface water presents the lowest potential cancer risk of the
scenarios evaluated. The excess cancer risk for an. adult is over 1 in 250,000, and the excess
cancer risk for a child is only about 1 in 1,400,000.
Based in part on the Baseline Risk Assessment, EP A has determined that actual or
threatened releases of hazardous substances from the Old Minot Landfill, if not addressed
by implementing the response acdon selected in this ROD, may present an imminent and
substSlntiAl endangerment to public health, welfare, or the environment.
DESCRIPfION OF ALTERNATIVES
VII.
1.
Alternative 1 - No Acdon
The Superfund program requires that the "no-acdon" alternative be considered at every site.
Under this alternative, EP A would take no further acdon to control the source of
contSlminSlnon and the cost would be zero dollars. The No-Action alternative would have
no impact on curre~t risk because the Baseline Risk Assessment concluded that currently
there are no complete exposure pathways and, therefore, current risk is insignificant.
However, potential future land-use scenarios, such as construcdon on the landfill site, exist
that could expose individuals to unacceptable risk. Funhermore, the No Acdon alternative
would not meet Applicable or Relevant and Appropriate Requirements (ARARs) because
leachate seeps are not acceptable under current North Dakota landfill design requirement
regulations, and ground water within the landfill (leachate) exceeds drinking water
Maximum ContSlminSlnt Levels (MCI.s) for several volatile organic compounds (VOCS).
2.
Alternative 2 - ~.pin~ ConsolliW,ion of Contaminated SotLJJnder the C~.
Leachate Extracdon andjreatment. Passive Landfill Gas CoJkmon. and Institutional
Controls. .
Alternative 2 incorporates removal, treatment, and containment technologies and could cost
between $1,185,900 and $2,152,300 to construct. Primary components of Alternative 2
include:
. Institutional controls to prohibit construction on the landfill, or the use of water
beneath the landfill and in the immediate vicinity of the landfill for drinking water
. purposes. . .
. Leachate extracdon to eHminate contSlminated ground-water migration from the
landfill area. ..
21
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"
. Leachate treatment in the Qty of Minot wastewater treatment fac:ility to levels
protective of human health and the environment.
. .
. Consolidation of contamin~ted soil in the vicinity of leachate seeps under the cap
and cap improvements to limit precipitation infiltration and control stormwater
nmoff.
. Ground-water monitoring to allow detection of future releases of contaminants to
the ground water outside the landfill area. Wells and gas probes within the limits
of waste will be properly abandoned
. Landfill gas collection, using, a passive trench vent system, to minimi7-C the
potential for adverse impacts to the cap due to gas buildup.
. Landfill gas collection, using a passive trench vent system, to manage the gas in
a manner protective of human health and the environment.
The passive gas collection system would be constructed after leachate levels are lowered by
the leachate collection system. It is expected that leachate levels would be lowered
sufficiently within 18 months of stan up of the leachate extraction system. If the leachate
extraction system does not sufficiently reduce leachate levels, additional wells would be
added.
Emission rates from the passive trench vent system would be estimated for sulfur oxides,
particulate matter, carbon monoxide, nitrogen dioxide, lead, hydrogen sulfide, and any other
pollutant expected. These rates would be included in an Air Pollution Emission 'Notice
(APEN) to be filed with the state prior to the start of construction. Additionally, the APEN
would include a modeled impact analysis of source emissions, a Best Available Control
Technology (BACI') review, and any other requirements necessary to conform to the State,
Air Quality Implementation Plan (SIP). The predicted emissions would be compared to the,
national primary and secondary ambient air quality standards cited in 40 CFR SO and 61,
and the final system would be designed to prevent emissioDS from exceeding these standards.
Monitoring the landfill gas emissions would be performed concurrently with ground-water
monitoring to ensure that the predicted emission rates for pollutants are n~t exceeded
Monitoring for odor would also be perf?rmed to satisfy regulatory requirements.
3.
Alternative 3 - Cappini- Consolidation of Contaminated Soil Under the 'Cap.
Leachate Extraction and Treatment. Active t ..andfill Gas Collection With Tall Stack
~n~ and Institu~onal Controls . '
Alternative 3 also incorporates removal, treatment, and containment technologies and c:ould
cost betWeen $1,084,400 and $2,050,800 to construct. The principal difference is the method
of collecting and venting landfill gases. Primary components of alternative 3 include:
22
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.
Institutional controls to prohibit conStruction on the landfill, or the use of water
beneath the landfill or in the immediate vicinity of the landfill for drinking water
purposes.
. Leachate extraction to eliminate contaminated ground-water migration from the
landfill area.
. Leachate treatment in the City of Minot wastewater treatment facility to levels
protective of human health and the environment.
. Consolidation of contaminated soil in the vic:inlty of leachate seeps under the cap
and cap improvements to limit precipitation infiltration and control stormwater
runoff.
. Ground-water monitoring to allow detection of future releases of contaminants to
the ground water. Wells and gas probes within the limits of waste would be
properly abandoned. .
.
Landfill gas collection, using an active collection system and a tall stack for
dispersion venting, to minimi.,.e the potential for adverse impacts to the cap due
to gas buildup. The system can be. upgraded to include gas flaring tecpnology, if
required in ~e future.
. Landfill gas collection, using an active collection system and a tall stack for
dispersion venting, to minimi7-e human exposure and to manage the gas in a
manner protective of human health and the environment. .
An active landfill gas collection system, consisting of leachate/gas collection wells and an
. active gas collection trench along the southeast limits of waste would be installed
The leachate/gas collection wells would become functional for landfill gas extraction after
the leachate level has been lowered to a depth of approximately five feet below the cap.
The period of time needed to implement this remedy is expected to range from one to two
years, and it is anticipated that remedial action objectives would be achieved in two to. three
years.
. .
The landfill gas would be extracted with a blower and vented and dispersed by means of an
elevated stack. . Emission rates from the active gas cOllection system and tall stack would
be estimated for sulfur oxides, particulate matter, carbon monoxide, nitrogen dioxide, lead,
hydrogen sulfide, and any other pollutant expected These rates would be included in an
APEN to be filed with the state prior to the start of construction. Additionally, the APEN
would include a modeled impact analysis of source emissions, a SAC!" review, and any other
requirements necessary to conform to the SIP. The predicted emissions would be compared
to the national primary and secondary ambient.air quality standards cited in 40 CFR 50 and
23
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-" ;~.n
" .....
"
61, and the final system would be designed to prevent emissions from exceeding these
standards. Additionally, the system would be designed to avoid concealing e~ons from
the landfill and to provide odor-free operation. Monitoring the landfill gas emissions would
be performed concurrently with ground-water monitoring to ensure that the predicted
emission rates for pollutants are not exceeded. Monitoring for odor would. also be
performed to satisfy regulatory requirements. .
VIII. SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES
As discussed above, site remediation alternatives have been developed that include
combinations of removal, treatment, and containment for the Old Minot Landfill Superfund
site. In ~ section, these alternatives are evaluated and compared to each other using the
following nine evaluation criteria to identify the alternative providing the best balance
among the criteria.
1. Overall Protection of Human Health and the EnVironment
2. Compliance with ARARs
3. Long-Term Effectiveness and Performance
. 4. Reduction of Toxicity, Mobility, and Volume Through Treatment
5. Short-Term Effectiveness
6. Implementability
7. Cost
8. State Acceptance
9. Community Acceptance
1. : This criterion is
categorized as a threshold criterion (i.e.. alternatives must pass this aiterion to remain in
the evaluation). This criterion assesses the protection afforded by each alternative
considering the long-term effectiveness and permanence, short-term effectiveness, and
compliance with ARARs. Protection of human health is assessed by evaluating how site
risks from each exposure route are eliminated, reduced, or controlled through the specific
alternative. This evaluation will take into account short-term or cross-mecija impacts that
result from implementation of the alternative remedial activity.
Alternatives 2 and 3 are. protective and are nearly equal in the level of protectiveness.
Both alternatives will limit exposure to contaminated ground water through: institutional
controls to prohibit use of water beneath the landfill or in the immediate vicinity of the
landfill for drinking water purposes; leachate extraction to eliminate COD~minated ground-
water migration from the landfill area; treatment of l~.achate to water quality levels
protective of human health and the environment; ground-water monitoring to allow for
detection of future releases of contaminants to the ground water. Each of the alternatives
will also limit exposure to contaminated soils by requiring that the soils be consolidated
under the cap.
24
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_._----~ _._~._----~----- -- -
Alternatives 2 and 3 will each employ a landfill gas collection system to minimi7.e
unconuoUed exposures to hllm~n~. Alternative 3 is more protective because the tall stack
vent will disperse landfill gas cont~min~nts, further limiting exposure to the gas. In contrast,
Alternative 2 allows the landfill gas to discharge to the atmosphere without designed
dispersion. Alternative 3 would also reduce the potential for landfill odors to nearby
residents.
Alternative 1, No Action, does not satisfy the requirement for overall protection of human
health and the environment. Under the No Action alternative, leachate seeps would
continue and high leachate heads in th~ landfill might encourage migration of cont~mina.nts
from the lanclfil1 in the future. Furthermore, the absence of land use controls may result
in future development of the landfill, as weU as the installation of ground-water supply wells
that might intercept leachate.
2 COlI\Pliance with ARARs: This criterion is also a threshold criterion in that all
alternatives must achieve compliance with ARARs to be considered as site remedies or, if
compliance is not achieved, a justifiable ARAR waiver must be obtained Section 121( d)
of the Superlimd Amendments and Reauthorization Act (SARA) mandates that for all
remedial actions conducted under CERCLA, cleanup activities must be conducted in a
manner that complies ~th ARARs. The National on and Hazardous Substances Pollution
Contingency Plan (NCP) and SARA have defined both applicable requirements and relevant
and appropriate requirements as follows:
. Applicable requirements are those federal and state requirements that would be
legally applicable, either directly or as incorporated by a federally authorized state
program.
. Relevant and appropriate requirements are those federal and state requirements
that, while not legally "applicable," are designed to apply to problems sufficiently
similar to those encountered at CERCLA sites that their application is
appropriate. Requirements may be relevant and appropriate if they would
otherwise be "applicable, " except for jurisdictional reStrictions associated with the
requirement.
. 'Other requirements to be considered are federal and state non-regulatory
requirements, such as guidance documents or criteria. Advisories or guidance
documents do not have the status of potential ARARs. However, where there are
no specific ARARs for a chemical or situation, or where such ARARs are not
, sufficient to be protective, guidance or advisories should be identified and used to
ensure that a remedy is protective.
Federal and state ARARs which must be considered include those that are: chemical-
specific, location-specific, and action-specific. Chemical-specific ARARs govern the extent
of site cleanup in terms of actual cleanup levels. Maximum contaminant levels (MCLs)
2S
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"
which must be met or maintained are chemical-specific ARARs. Location-specific ARARs
govern natUral site features such as wetlands, floodplains, and man-made features such as
existing landfill and disposal areas. Action-specific ARARs are technology or ac:tivity~based
requirements that set restrictions on particular kinds of action at CERClA sites.
. .
, Compliance with these requirements was evaluated for each alternative. For alternatives
which do not comply with the requirements, justification for a waiver under CERClA is
discussed
Alternatives 2 and 3 will achieve compliance with Safe DriJ11cing Water Act (SDW A) MCL
requirements. Leachate extraction will limit contaminant migration and ensure that SDW A
MCLs will not be exceeded for ground water in the immediate vicinity of the landfill
Treatment pf leachate in the City of Minot wastewater treatment facility, with no pre-
treatment, will meet SDW A MCls and National Pollution Discharge RHmination System
(NPDES) requirements. .
In the event that additional gas management becomes necessary to protect human health
and the environment, Alternative 3 could be modified to incorporate gas flaring' or other
technologies. '
Alternatives 2 and 3 meet the substantive requirements, of the State's Solid Waste
Regulation, with the exception of cap permeability. Oay soils near the site can only be
recompacted to a permeability slightly greater than the State standard of 1.0E-07 em/see.
However, the combination of landfill capping and leachate extraction meet the requirements
of Section 121(d)(4) of CERClA for a waiver from an ARAR since an equivalent standard
of performance will be attained through use of another method or approach.
Alternative 1 will not satisfy SDWA MCLs for ground wa~r. 't(ithin the landfill. This
alternative will also not satisfy SDW A M~- for ground water outside the landfill penmeter,
if there is future contaminant migratioIli'-
The next five criteria are designated as balancing criteria. These criteria are used to
measure the positive and negative aspects of performance, implementability, and cost for
each alternative.
3. Loni-Term ~eness and Permanence: The focus of this evaluation is to
determine the effectiveness of each alternative with respect to the risk posed by treatment
of residuals and/or untreated wastes after the cleanup criteria have been achieved Several
components were addressed in making the determinations, including: .
. MagnitUde of residual risk from the alternative.
.
Likelihood that the alternative will meet process efficiencies and performance
specifications.
26
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. Adequacy and reliability of long-term management controls providing continued
protection from residuals. .
. Associated risks in the event the technology or permanent facilities must be
rep~d .
Alternatives 2 and 3 provide nearly equal long-term effectiveness and permanence.
Alternative 3, which includes dispersion of landfill gas by discharge of collected gas through .
a tall stack, is more effective because of the dispersion of the cont~minants in the landfill
gas.
The adequacy and reliability of. controls for the operation of the remedy are equal in
Alternatives 2 and 3. Alternative 3 is more complicated because additional maintenance
would be required to assure perf0rma.D:ce of the active gas collection system blower.
Both Alternatives 2 and 3 require and include ground-water monitoring for evaluation of
the long-term effectiveness of the remedy.
Alternative 1, No Actio~ provides no long-term protection or effectiveness and could result
in elevation of risk levels beyond the acceptable risk range identified in the NCP.
. 4. v: This criterion
evaluates the ability 9f the alternatives to significantly achieve reduction of the toxicity,
mobility, or volume of the contaminants or wastes at the site, through treatment. The
criterion is a principal statutory requirement of CERClA This analysis evaluates the
quantity of cont~minants treated and destroyed, the degree of expected reduction in toxicity,
mobility, or volume measured as a percentage or reduction, the degree to which the
treatment will be irreversible, the type and quantity of residuals produced, and the manner
in which the potential threat will be addressed through treatment. The risk posed by
residuals will be considered in determining the adequacy of reduced toxicity and mobility
achieved by each alternative. .
Alternatives 2 and 3 both reduce the volume of leachate and therefore provide control over
mobility of leachate constituents in leachate seeps and in the. ground-water system. Both
Alternatives 2 and 3 involve treatment of leachate in the Cty of Minot wastewater
treatment facility. This treatment is irreversible and both Alternatives 2 and 3 are affected
to the same extent. Wastes at the site would not be treated under either of these
alternatives but would be isolated from potential receptors through containment, thereby
reducing the mobility of the waste. Alternative 3 could also provide additional treatment,
if necessary, of landfill gas discharges by means of a gas flaring system, which is not possible
with Alternative 2.
The No Action alternative provideS no reduction in toxicity, mobility, or volume.
27
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.
s. Short-Term Effectiveness: The short-term effectiveness of each alternative was
assessed based on the risk associated with the implementation of the remedial "action to the
community, workers, and environment and the time required to achieve the" response
objectives. Measures to mitigate releases and provide protection are a key issue in this
determination.
. .
Alternatives 2 and 3 both involve excavation for installation of leachate extraction wells and
a gas extraction system. Workers could be easily protected for both alternatives through
implementation of appropriate health and safety and contingenc.y p):lnning Alternative 2
could require Level B health and safety standards for construction of the deep" passive vents
while Alternative 3 is likely only to require Level C for construction of the extraction wells.
Risks to the commnnity during implementation of the alternatives are expected to be
minim:ll sin~ the site is fenced and access "will be conttolled
For both Alternatives 2 and 3, the time required until the Remedial Action Objectives are
met is the same. It is anticipated that two to three years would be required to draw the
leachate head levels down to the levels established in the Remedial Action Objectives. The
other Remedial Action Objectives would be met immediately following completion of the
installation of the cap and gas extraction system. Alternative 1, No Action, is not effective
in the short-term. .
6. Implementability: This criterion analyzes technical feasibility, ailminiqrative
feasibility, and the availability of services and materials. Technical feasibility assesses the
difficulty of construction or operation of a particular alternative and unknowns associated
with process technologies. The reliability of the technologies based on the likelihood of
technical problems that would lead to project delays is critical in this determin~tion. The
ability to monitor the effectiveness of the alternative is also considered
Ailmini~ttative feasibility assesses the ease or difficulty of obt:lining permits or rights-of-way
for construction. Availability of services and materials evaluates the need for off-site
treatment, storage, or disposal services, and the availability of such services. Necessary
equipment, specialists, and additional resources were also evaluated in determining the ease
by which these needs cOuld be fulfiJled
Alternatives 2 and 3 have nearly equal implementability factors. Both use proven existing
technologies and the permits and regulatory requirements associated with implementation
of the technologies are identical. Also, it has been determined that for either alternative;
the City of Minot wastewater treatment facility has the capacity to accepi leach,te from the
land.6l1. In addition, there are sufficient quantities of locally available clay soil for the
specified cap repair requirements discussed in either Alternative 2 or Alternative 3.
There may be some difficulties with implementing institutional controls because the City of
Minot does not own the entire site. Although the City has had no difficulty in obt:lining
access to conduct field investigations and to implement the removal action, property rights
28
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. issues may make long-term enforcement of deed restriCtions and other institutional controls
more difficult. Alternative 3 would be more difficult to implement because of the additional
mechanical complexity of operating a blower.
7. ~: Alternatives are evaluated for cost in terms of capital costs, annual or
operation and maintenance costs (O&M)t and present worth cost. Capital costs include the
sum of the direct capital costs (materials. equipment, labort land purchases) and indirect
capital costs (engineering. licenses. or permits). Annual costs include the cost for labort
operation and maintenancet materials. energyt equipment replacement, disposal. and
sampling to operate the treatment facilities. Present worth costs include capital costs and
O&M costs calculated over a SO-year period.
The present worth analysis is used to evaluate expenditures that would occur over an
assumed SO-year operation period by discounting all future costs to a common base year.
This allows the cost of remedial aCtion alternatives to be compared on the basis of a single
figure representing the amount of money that, if invested in the base year and disbursed as
needed. would be sufficient to cover all costs associated with the remedial alternatives over
its planned life.
Assumptions were made for each of the proposed remedy components to allow each
alternatiVe to be analyzed and compared. These assumptionst such as the amount of
additional clay material which will be necessary to effect an adequate caPt were based on
engineering judgmenf and characterization studies. performed during the RI. The
assumptions. and consequently the cost estimates. will be revised as remedial design
activities proceed and a more detailed design is developed.
The cost analysis was bifurcated to acknowledge two possible scenarios. The first scenario
is based on the assumption that the City of Minot would implement appropriate portions
of the remedial action using city-owned fill material. labort equipment, and/or locally
contracted labor. A detailed cost estimate for this scenario may be found in the FS and is
represented by the lower cost estimates. Costs for this scenario are based on unit cost
estimates provided by the City.
The second scenario assumes that the remedial action would be implemented by either EP A
or a private party other than the City of Minot Detailed cost estimates for this scenario
may also be found in the FS. For either this scenario or the City of Minot scenariot the
remedy components will be protective of human health and the environment.
. .
Under either scenariot remedial design efforts may. reveal that it is possible to significantly
reduce the original project cost estimates. Reductions in the estimated costs could be the
result of value engineering conducted during the remedial design. . Through the value
engineering process. modifications could be made to functional specifications of the remedy
to optimize performance and minimi7.e costs. These changes would fall within the definition
29
.
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~.' , ,', .-'. ,'.
.,,~
..
.
of' li6Oii-Sigriificant modifieatfons," as defined by EP A guidance for preparing superfund .
decision documents.
i' ,",
. .
For example, it may be determined that a reduction in costs could be effected by. non-
significant changes to the type, quantity, and/or cost of materials, equipment, facilities,
services, and supplies used to implement the remedy. It should be noted that this type of
design variance may have a noticeable impact on the estimated cost of the remedy, but will
not affect the remedy's ability to comply with performance standards.
For the scenario in which it is assumed that the Oty of Minot will finance the cleanup
activities, capital and present worth costS are currently estimated to be as follows. '
Alternative 2:
Capital CostS
Present Worth Costs
$1,185,900
$1,555,100
Alternative 3:
Capital CostS
$1,084,400
Present Worth CostS
$ 1,531,500
Again, reductions in these estimated costS may occur as the result of value engineering
conducted during the remedial design.
The second scenario assumes that the remedial action would be implemented by either EP A
or a private party other than the City of Minot. These estimates are described in greater
detail in the FS.
Alternative 2:
Present Worth CostS
$2, 152,300
$2,561,~
Capital Costs
Alternative 3:
Capital Costs
$2,050,800
$2,537,800
Present Worth CostS
30
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Capital costs for each alternative, under either scenario, are s~. Alternative 2 is more
expensive than Alternative 3 because of the costs associated with the construction of the
passive gas collection system. Tbe difference in the present worth costs is also attributed
to the costs of material and construction for the passive gas system. While construction of
the passive gas system (Alternative 2) would be more expensive than the construction of the
active gas collection system (Alternative 3), there are significant operation and maintenance
costs for the active landfill gas collection system in Alternative 3.
.
o .
"
8. State Acceptance: This modifying c:riterion evaluates the technic:al and :tdmini~trative
issues that have been raised by the Sta~ of North Dakota. The State of North Dakota was,
provided the opportunity to review and comment on: RI/FS documents; the remedial
investigation and feasibility study reports; and the draft Proposed Plan. In addition, the
State submitted comments on the Proposed Plan during the public comment period, which
began on January 4, 1993 and concluded on March 4, 1993.
In accordance with the requirements of the NCP, the State of North Dakota was also
provided the opportunity to review and comment on the Record of Decision. As a result
of that review, the State of North Dakota chose to concur with the selected remedy.
Comments from the State, as well as EPA's responses to those comments, are provided in
the Responsiveness Summary (Appendix B).
9. CommunitY Acceptance: This modifying c:riterion evaluates comments and concerns,
on the Proposed Plan.; received from members of the community. The public comment
period for the Proposed Plan began on January 4, 1993 and concluded on March 4, 1993.
A public meeting was held on January 19, 1993, in Minot, North Dakota. Although no,
written commentS were received from the general public, written commentS ~ received
from loc:a1 and state governmental entities, Minot area business org~ni7.ations, several
potentially responsible parties (PRPs), and all members of the North Dakota Congressional
delegation. '.
All the written comments that were received by EPA were in support of the City of Minot's
proposal/comments on the Proposed Plan. In principle, the City's proposal was found to
be consistent with the preferred alternative that was proposed by EPA. A snmm~ry of (a)
the City's proposal, (b) all other written comments, and (c) EPA's responses to those
comments,. may be found in the Responsiveness Summ:uy (Appendix B). The
Responsiveness Snmmary also includes EP A's answers to the questions/commentS that were'
posed during the, public meeting. .
IX.
SELECTED REMEDY
Based on consideration of the requirements of CERCLA, the detailed analysis of
alternatives, and public comments, both EP A and the State of North Dakota have
determined that Alternative 3: capping, consolidation of contamin~ted soil under the cap,
31
.", . "'b.
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. .'.
"
leachate extraction and tteatmen~ active landfill gas collection with tall stack venting, and
institutional controls is the most appropriate remedy for the Old Minot Landfill in Mino~
North Dakota.
. .
The selected remedy incorporates removal, treatment, and' containment technologies.
Primary components of the remedy and their impact on remediation goals are discussed
below. Estimated costs for the components of the selected remedy are provided in Tables
5 and 6. Table 5 lists costs that may be expected by assuming that the Cty of Minot will
construct the remedy using city employees or locally contracted labor, and city-owned fill
material for capping and grading. Table 6 lists estimated costs for the remedy components
under the scenario in which a private party would be performing the cleanup.
1.
Leachate' Extraction and Treatment in the CitY of Minot Wastewater Treatment
.flmi
Leachate will be extracted from leachate extraction wells. The leachate from each well will
be pumped to a common header pipe which will be discharged to the Cty of Minot sewer
system and conveyed to the municipal wastewater treatment facility. for treatment.
The reduction in leachate head afforded by the extraction system will eliminate seeps and
reduce leachate pressure that might cause future leachate migration to the ground-water
system. Leachate will be pumped continuously to maintain a leachate level of approximately
5 feet below the cap.
2.
I.andfill Gas Collection
An active landfill gas collection system will be installed, and the gas will be drawn off by
means of a blower and subsequently vented and dispersed through a tall stack. The
leachate/gas collection wells will become functional for landfill gas extraction after the
leachate level has been lowered to a depth of approximately five feet below the cap. The
period of time needed to implement this remedy is expected to range from one to two years,
depending on the time required to sufficiently lower the leachate level in the landfill. It is
anticipated that site remediation goals will be attained with this remedy within a period of
two to three years. . .
3.
Consolidation of Contaminated Soil Under the C~p
Soil in the vicinity of landfill seeps will be scraped to a depth of approximately 3 feet and
consolidated 'under the landfill cap. The contaminated soils in the vicinity of the landfill
seeps are generally on the existing I8ndfill cap; therefore, this consolidation operation can
be accomplished at the same time that cap modifications are being constructed.
32
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TARtE 5
COST SUMMARY FOR THE SELECl'ED REMEDY
(City of Minot Implementation)
Old Minot Landfill Superfund Site
Minot, North Dakota
Module
Caital
. p
Costs
Annual
Costs
Present Worth
Costs
L EDginecriDg and Scicntif1c Services
A. Data Gathering $ 13,400
B. P"r~.eriDg $122,000
C. Coastruction Related Services. $174,400
D. Present Worth. of Module 1 $ 309,800
2. F'mal Cover and Grading
A. Materials &. Coastruetion $492,SOO
B. O&M $ 5,600
C. Present Worth Module 2 . SS55,700
3. Leachate Collection
A. Materials &. Construction S230,100
B. O&M $ 25,800
C. Present Worth of Module 3 SS20,8OO
4. Active Landfill Gas CoUcctioo
. A. Materials &. Construction $52,000
B. O&M $ 5,400
C. Present Worth of Module 4 $ 112,300
S. MoDitoriDg
A. Capital Costs
B. Annual Costs $ 2,900
C. Present Worth of Module S $32,900
Total Capital Costs $1,084,400
Total Annual Costs $ 39,700
Total Present Worth of Selected Remedy S1,S31,SQO
33
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. 0
TABLE 6
COST SUMMARY FOR TIlE SELECTED REMEDY
(Private Party Implementation)
. .
Old Minot Landfill Superfund Site
Minot, North Dakota
Module
Capital
Costs
Annual
Costs
PrescDt Worth
Costs
1. Fng;n~ and Scientific Scniccs
A. Data GatheriDg $ 13,400
B. EnginccriDg $122,000
C. CoDStrUctiOD Related Services $174,400
D. PreseDl Worth of Module 1 $309,800
2. Fmal Cover and (jradiDg
A. Materials & CoDStrUctiOD $ 1,411,900
B. O&M $ 9,200
C. PrcscD1 Worth Module 2 $ ~1S,300
3. Lcac:hatc Collection
A. Materials &. Constroction $ 230,100
B. O&M $ 25,800
C. PreseDt Worth of Module 3 $ S2O,8OO
4. Active Land.fi11 Gas CollectioD
A. MatcriaJs &. ConstructiOD $52,000
B. O&M $ 5,400
C. PrcscD1 Worth of Module 4 $ 112,300
.
S. MODiIoring
A. Capital Costs $ 47p:yJ
B. Annual Costs $ 2,900 .
C. PrcscD1 Worth of Module S $ 79,600
Total Capital Costs $ 2,OSO,8OO
Total Annual Costs $ 43,300
Total PreseDl Worth of Selected Remedy $ 2,537,800
34
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4.
T ~nnfill Ca.p,pine
The landfill cap will be reconstrUcted in order to provide more effective surface water
contro~ repair cap damage in the area of the landfill seeps, and comply with the substantive
requirements of federal and state landfill regulations regarding final cover design. The new
capping system will consist of, in part, a perimeter diversion berm which will prevent runoff
outside the landfill limits from flowing onto the landfill cap, as required by federal and state
ARARs. The berm will also stabilize the limits of the waste. The new capping system will
incorporate a surface water runoff sedimentation basin to collect sediments from the landfill
cap and perimeter ditches. '
The cap itself will be consttucted by scarifying and recompacting the existing cover soils
when existing grades are close to proposed grades and when existing materials meet design
cap requiremel1ts. In all other cases, additional material will be brought in to raise existing
grades, meet design requirements, or both. Erosion control matting will be placed where
necessary to establish and maintain a vegetative cover. A vegetati~ "CQyer will be ~ "
established over all disturbed areas including the site berm, sedimentation basm, and landfill' . '
cover.
5.
, Institutional Controls
The selected remedy includes institutional controls to prohibit future land use developments
at the landfill that would cause unacceptable exposure to landfill contents or gas. The
institutional, controls include prohibition on land use that would da.mage the cap and
prohibition against the installation of ground-water supply wells through the landfill or in
the immediate vicinity of the landfill. The institutional controls will be effective indefinitely.
Implementation of institutional controls will require agreements with landowners of the
landfill site as well as those adjacent to the site.
6.
Monitorine
Ground-water monitoring will continue during and following implementation of the remedial
action in order to, document that the source control remedy is adequate over the long-term
to maintain ground water outside of the landfill at acceptable quality levels. The monitoring
wells installed during the Remedial Investigation will be used in the long-term groUnd-water
monitoring program. Monitoring wells installed in the landfill itself, along with previously
installed gas wells, will be abandoned during implementation of the selected remedy.
The monitoring program will begin with four quarterly sampling events the first year and
continue with annual sampling and analysis of the ground-water samples from the-
monitoring wells. Sampling and analysis will be done for VOCS and inorganic and org'anic
chemicals that have maximum con~minant levels (MCLs) cited in 40 CFR 141.11 and 12,
and 40 CFR 141.60 and 61; maximum contaminant level goals (MCLGs) cited in 40 CFR
141.50; or secondary maXimum contaminant levels (SMCLs) cited in 40 CFR 143.03. The
35
.
o
. '",
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. .
four quarterly sampling events will determine the baseline ground-water quality. After that,
annual monitoring is recommended since the ground-water flow rate in the geologic
materials in the vicinity of the landfill is low. Annual monitoring will be adequate to
identify any changes in ground-water quality in the immediate vicinity of the landfill.
Routine monitoring will also be required for the leachate that is discharged. to the Minot
wastewater treatment facility. Monitoring requirements will include the analysis of monthly
grab samples for chemical oxygen demand (COD), biochemical oxygen demand (BOD), total
suspended solids, and pH, as well as the analysis of quarterly grab samples for VOCs,
metals, and chemicals that have MCLs, MCLGs, or secondary maximum cont~min9nt levels
(SMCLs). One toxicity screening test will.a1so be performed prior to initial discharge.
The required range of analytical parameters for the ground water and leachate monitoring
programs may be reviewed on an annual basis and may be modified, as appropriate and only
after approval from EP A These modifications will be based upon trends .that will be
established from the accumulated results of the previous sampling events.
Remediation Goals and Performance Standards
Remediation goals for protecting human health and the environment are based on risk-
related considerations such as cleaning-up media to reduce intake of CODtaminants or
isolating the cont9m1n9ted media to eHm1n9te the exposure pathway and to comply with all
applicable or relevant and appropriate requirements. Existing site conditions, evaluated
within the context of current land use and access restrictions, do not present an
nn9cceptable risk. However, future changes in land use or site activities could expose
h11m9n~ to greater than acceptable risk. The primary purpose of this response action is to
control or mitigate unacceptable potential future risks posed by the direct inb91~tion of
landfill gases and contact with or ingestion of ground water cont9min9ted by leachate.
Performance standards are those standards which the remedy shall achieve in order to
satisfy the remediation goals. . Additional performance standards information may be found
under Section VIII, Item 2 of this document and in Appendix A Measurement protocols
for determining compliance with the remediation goals and performance standards will be
developed during the remedial design.
Remediation Goals
Performance Standards
(1) Prevent direct contact with landfil1
contents including the solid waste,
leachate, and gas.
(1) Minimum three-foot clay cap over the
Ian. consistent with substantive
requirements of North Dakota Solid
Waste Management Act and pertinent
federal Solid Waste Land Disposal
requirements [40 CFR Parts 241 and 257]
36
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(2) m~nAge leachate: to limit future
leachate migration out of the landfill to
ensure a low risk to potential ground
Water receptors; and to maintain ground-
water quality outside the landfill within
drinking-water standards.
(3) treat or isolate soils in the immediate
vicinity of leachate. seeps to prevent
contact or ingestion that would result in
unacceptable carcinogenic or
noncarcinogenic risks. .
(4) control leachate seeps to prevent the
movement of cont9minants by surface flow
to off-site soU and surface water.
. . .' ,
. (5) IJ1Anage landfill gas to ensure a low
risk to air receptors.
. and Surface Water Control requirements
[40 CFR Part 264].
(2) Water quality standards in accordance
with SDWA [40 CFR Parts 141 and 143] .
and NPDES [40 CFR Parts 125, 136, and
403] requirements. Ground water
adjacent to the landfill shall not contain
cont~minants at levels that cause the
ground water to exCeed the 1.0E-04 to
1.0E-06 risk range for carcinogens, or the
hazard index to exceed 1 for
noncarcinogens for potential receptors
located adjacent to the landfill.
(3) ContAmina.ted soils shall be removed
to a depth of approximately three feet and
consolidated under the landfill cap,
consistent with substantive requirements of
North Dakota Solid Waste Management
Act and pertinent federal Solid Waste
Land Disposal requirements [40 CFR
Parts 241 and 257].
(4) Landfill cap shall be reconstrUcted in
accordance with substantive requirements
of North Dakota Solid Waste
Management Act and pertinent federal
Solid Waste land Disposal requirements
[40 CFR Parts 241 and 257] and Surface
Water Control requirements [40 CFR Part
264]. . .
(5) Air quality standards in accordance
with pertinent requirements of 40 CFR
Part 6, Subpart C, Parts 50, 52, 61, and
241, the North Dakota Solid Waste -
Management Act, and the North Dakota
Air Pollution Control Regulations. Air, at
or liear the landfill surface, shall not
contain contAminAnts at levels that cause
the air to exceed the 1.0E-04 to 1.0E-06
risk range for carcinogens, or the hazard
37
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. .
. .
(6) t1'1anage landfill gas to reduce gas
'pressure within the landfill in order to
protect the cap. '
(7) manage landfill gas to reduce pressure
head buildup of leachate on the' landfill
base to minimi'7.e leachate migration to
ground wat~r.
(8) manage leachate to prevent
exceedances of water quality standards in
natural surface waters due to stonnwater
runoff from the site or discharge from a
treatment faCility.
x.
STATUTORY DETERMINATIONS
index to exceed 1 for noncarcinogens for
potential receptors located adjacent to the
landfill.
(6) Pertinent requirements of the North
Dakota Solid Waste Management Act and
federal Solid Waste Land Disposal
requirements [40 CFR Parts 241 and 257].
(7) Pertinent requirements of the North
Dakota Solid Waste Management Act and
federal Solid Waste Land Disposal
requirements [40 CFR Parts 241 and 257].
(8) Water quality standards in accordance
with SDWA [40 CFR Parts 141 and 143]
and NPDES [40 CFR Parts 125, 136, and
403] . requirements, Standards of Water
Quality for the State of North Dakota, and
North Dakota Pollutant Discharge
Elimination System regulations.
Under its legal authorities, EPA's primary responsibility at Superfund sites is to undertake
remedial actions that achieve adequate protection of human health and the environment.
In addition, Section 121 of CERCLA establishes several other statUtory requirements and
preferences. These specify that when complete, the selected remedial action for a site must
comply with applicable or relevant and appropriate environmental standards established
under Federal and State environmental laws unless a statutory waiver is justified. The
selected remedy must also be cost effective and utilize permanent solutions and alternative
treatment technologies or resource recovery technologies to the maYimum extent practicable.
, Finally, the statute includes a preference for remedies that employ treatments that
permanently and significantly reduce the ,volume, toxicity, or mobility of hazardous wastes
as their principal element. The following discussion addresses how the selected remedy
meets these statutory requirements. ' -
-
1.
Protection of Human Health and the Environment
The selected remedy will protect both human health and ihe environment. The leachate
extraction and treatment system will minimi7.e the potential for any future off-site migration
of landfill leachate into the ground-water system. The landfill gas collection system will
reduce landfill gas pressure. which should reduce stress on the cap and the pressures within
38
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the landfill that might encourage future outfl9w of leachate into the ground-water system.
Cap improvements will e1iminate the possible exposure of receptorS to leachate and landfill
waste. Institutional controls will prohibit future land uses that could damage the in-place
remedial action. Finally, ground-water monitoring will assure that there is early warning of
any future failure of the remedy.
2
COl1\Pliance with ARARs
The selected remedy of capping, consolidation of contaminated soil under the cap, leachate
extraction and treatment, active landfill gas collection with tall stack venting, and
institutional controls will substantively comply with all applicable or relevant and
appropriate chemical- and action-specific requirements (ARARs). No location-specific
ARARs are identified for the site. Federal and state statutes and regulations pertinent to
the selected remedy are presented below. .
Federal:
.. Oean Air Act (CAA)
. Oean Water Act (CWA)
. Safe Drinking Water Act (SDWA)
. Resource Conservation and Recovery Act (RCRA; Non-Hazardous> Waste
Subtitles)
. Comprehensive Environmental Response, Compensation and Liability Act
(CERClA)
State:
. North Dakota Solid Waste Management Act
. North Dakota Pollutant Discharge Elimination System (NPDES) Regulations
. Standards of Water Quality for the State of North Dakota
. North Dakota Air Pollution Control Regulations
.
Specific federal ARARs pertinent to the selected remedy are presented in the remedy
compliance analysis in Table A-I of Appendix A Specific state ARARs, with which the
selected remedy may be required to comply, are evaluated in Table A-2 of Appendix A
The selected remedy has provisions for landfill gas dispersion following venting from the
landfil1. The component of the remedy that addresses discharge of landfill gas could be
affected by future changes in the Oean Air Act regulations or state regulations affecting
landfill gas emissions. Without treatment, the landfill gas emissions will result in a release
of less than I pound per day of total VOCs to the atmosphere. This emission rate is less
than anticipated future control requirements.
39
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. 0
The landfill materials are not classified as a hazardous waste; therefore, only the provisions
of the Resource Conservation and Recovery Act that relate to non-hazardous municipal
waste will apply. The design of the remedy will meet the substantive provisio~ of these
requirements. Specific requirements are incorporated in and controlled by the State Solid
Waste Regulations. .
The Oean Water Act regulations apply to the treatment of the leachate in the City of Minot
waStewater treatment facility and the subsequent impact on the Souris River downstream
of the facility's discharge point. Treatment of leachate in the City of Minot wastewater
treatment facility will meet all of the provisions of the Oean Water Act as discussed in the
City's NPDES Permit. Pretreatment of leachate, prior to treatment in the wastewater
treatment plant is not required now, but may be required in the future if CW A regulations
. change.
. .
The primary state ARARs controlling the remedy are the State's Solid ~aste Regulations.
The remedy meets the substantive requirements. of these regulations with the exception of
cap permeability. Clay soils in the vicinity of the Old Minot Landfill can be recompacted
to a permeability of slightly greater than 1xlo-7 em/see. The state standard for permeability
is 1xlo-7 em/see. However, engineering analysis of the cap indicates that there will be no
significant increase in average precipitation inflow through the cap, given the minor
deviation from the permeability requirement. Furthermore, the leachate extraction system
will be in place and will be able to maintain leachate levels regardless of minor variations
in cap permeability. Therefore, the combination of the landfill cap and leachate extraction
system meet the requirements of Section 121(d)(4) of CERCLA for a waiver from an
ARAR. The specific ARAR waiver is "An alternative remedial action will attain an
equivalent standard of performance through the use of another method or approach." This
waiver will be invoked if EP A determines that areas of the existing cover are sufficiently
thick and compact so as to make placing six inches of topsoil and repairing erosion rills
sufficient to decrease infiltration to levels whic~ in turn, can be controlled by the leachate
extraction system. .
3.
Cost Effectiveness
The selected remedy has been determined to provide overall effectiveneSs proportional to
its costs and is therefore considered cost effective. The net present worth value ranges from
Sl,531,500 to S2,S37,800 and reflects the differences ~tweei1 QV~rallproject costs assuming
the City of Minot does the work with city-owned mate~ and 'city employees or locally
contracted labor, and project costs for a private party other than the Oty. The estimated
costs of the selected remedy are slightly less than the costs associated with the similar
alternative developed that uses a passive gas venting system, yet the selected remedy
. provides a higher degree of protectiveness due to dispersion of gases through a tall stack.
All of the technologies included in the remedy are readily implementable and have been
widely used and demonstrated to be effective. In addition, the selected remedy can be
40
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upgraded to include gas flaring technology if .necessary to provide additional protection to
human health and the environment.
4.
. ~ermanent SoJ.mions and..Altema~Treatment TechnoloiPes (or
Resource Recove~ ~e$) to the ~l1m Extent Practicable
EP A and the State of North Dakota have determined that the selected remedy represents
the may;mum extent to which permanent solutions and treatment technologies can be
utilized in a cost-effective manner for the Old Minot Landfill Superfund site. Of the
alternatives that are protective of human health and the environment and comply with
ARARs, EP A ;md the State have det~rmined that this selected remedy provides the best.
balance of tradeoff's in t~rms of long-term effectiveness and permanence; reduction in
toxicity, mobility, or volume achieved through treatment; short-term effectiveness;
implementability; cost; and the statutory preference for treatment as a principal element.
The selected remedy is expected to be permanent and effective over the long-term as long
as routine maintenance on the cap, leachate extraction system, and gas system is performed.
The remedy is eXpected to eliminate leachate surface seeps and to permanently minimi7.e
migration of leachate to the surrounding ground-water system. The present outflow of
leachate to the ground-water system is believed to be relatively minor, and the added design
features of leachate head-level maintenance and capping will add a safety factor to the
current landfill contamin;lnt migration controls..
There will be a reduction in volume through treatment because the leachate will be
. extracted from the landfill to reduce the long-term leachate levels, and the leachate will be
treated in the City of Minot wastewater treatment facility. There are no special
requirements for the treatment process and the treatment is irreversible.
5.
Preference for Treatment as a Princtpal Element
The selected remedy is protective of human health and the environment, substantively
complies with federal and state requirements that are legally applicable or relevant and
appropriate to the remedial action, and is cost effective. A waiver from ~e North Dakota
standard for landfill cap permeability is justified under the requirements of Section
121( d)( 4) of CERaA since the combination of landfill capping and leachate extraction will
attain an "e(pDvaIent standard of performance through the use of another method or
approach. . This remedy utilizes permanent solutions and alternative treatment (or resource
recovery) technologies to. the m3y;mum extent practicable for this siie. There are no
principal threats at the site. However, this remedy satisfies the statutory preference for
treatment as a principal element of the remedy through treatment of the leachate. The size
of the landfill and the fact that there are no on-site hot spots that represent the major
sources of contamination preclude a remedy in which contaminants could be excavated and
treated effectively.
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. 0
. 0
APPENDIX A
Table A.1 Pertinent Federal ARARs and Compliance Analysis
Table A.2 Documentation 01 State ARARs
-------
Secause 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 remedial
action to ensure that the remedy continues to provide adequate protection of human health
and the environment.
...~.., ".~
42
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Acboas CitaIioD RcquiraDeat SeJcae4 ~~ .-.:: " ..
40 CfR 61.19 Probibirs COII~li"l ewo~ Comp1iaDce wi&h this ARAIl will be
~
Discbarge to POTW 40 CfR 125.1-3 J:'ct..Wip- criIcria uad staDdard The FS shows that die P01W will
for tecbDology-bascd rcquircmCDCS meet its NPDES permit Jilpit..,;,....s
iD permits UDder Sec:tio- 301(b) Tbercforc, this ARAR wiD be
aDCI G of the CWA. acb.iewcL
40 CfR 136.1-5 uad Speci6cs ualyIical .,..-durcs for The FS shows that die POTW will
AppeDdj~ A.c NPDES applicatu- ad reports. meet its NPDES permit =,it..ti",,!:
Tbercforc, this ARAR will be
acIUed.
40 CFR 403.5 PoJhlt.,," that pall tbroaP die The CJ"...titi-, of poDatuats that
POTW widaout tft8,....-~, iDtcrfcre will pili tbrousb die P01W haw
wi&h P01W operatioD. or beeD dctenDiDcd to be inciK"ifi{'l1't
CC)IIIt....nult~ POTW sIudp are
proa-ibit..d lDtcrfereacc wid1 POTW opcraUoD
is addrea.scd iD the FS.
'-
Cont_in.tinn of POTW sludge is
addressed iD die FS.
Based upoD these diJenccimJs, this
ARAR will be ac:bic¥ed.
40 CfR 403.5 ud Di!:::~,~ mast comply willa local Compliaace with this ARAIl will be
local POTW regul- pc.' ~ programs. adUeved.
atioas iDc.' ,'POTW-spcci&
poi:. c. spin pmatioD po\l(P'aJD
req:.. '~ aDd rcportiDg aad
m~., : requiremCDCS.
-
40 CfR 403.5 Specii~, ,. ;2ibitioas predudc the CompliaDce wi&h this ARAIl will be
disdw~.:" ~ to POTWs acbieYed..
that:
- Crcat.; ,":re or aplosioD
haDn; De POTW.
- AM carro.: ',: (pH < S.o).
- 0bsInKt G' .'!esaIbDg iD
iDtafcrcncc.
.
- Jve disC:.:.::~' ': a flow rare
-lor ClDC:-'-" :-.31 that will
rauIt iD imcrfae. ,:.
- IIICI'C8IC die taDpCra1.;.:~::f "
W8ItCW8Ier adaiDg the
IrabDCIIt plat that woaki : ~. i
suit iD ~eacc.. bat iD DO
cae nile the POTW iDf1w:DI i
temperature above ~ F (4fP
C).
OperaUOD aDd 40 CFR 264.118 Post-dosure care to casare that CompliaDce with this ARAR will be
MaiDteD3Dcc (RCRA. Subpart G) site is maiDtaiDcd aDd mODitorcd. acmc-L i
.; ;.
'J
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Table A~l
PERTINENT FEDERAL ARARS AND COMPUAi'llCE ANALYSIS
Old Minot Landfill Superfund Site .
Minot, Nonh Dakota
Adioas Cit~tiNo ReqaimDat Selected Remedy I
Air StrippiD& 40 CfR 6.303 Rcqaira aD fcdenl projccII, CompliaDcc with this ARAR will be
C~tioa. Iiccua, pcrmiII. plus. aDd achiewd.
E:IcavIdaa, uci Ga h.M,1 ~.~ acIiviI:ia to
Co~ ~ to 111.'/ State Air Quality
Impl-_tiNo PIa (SIP). .
40 CfR 5O.1~ a. 9, 1:-"""'" UIioaIl prim8ry 8DII ~p~ ~-this ARAR will be
11,12,- ~.., .-J.:-t air quaGty .. acbieftcL
A~~ A., If, J, It staIIdudL Tbe ~- provide
- metbods 8DII pt~~ b
.
lDC;uUI;..g specific air ponutaDIS. .
.
. CAA SecIba 101 aad Desip system to provide odor-free ColDpliaDc:e with this ARAR will be
40 CfR 52 operaIioa. a~
40 CfR 52 File aD Air PoDutioD Flllic.Unn ComptiaDcc with this ARAR WiD be
Notice (APEN) with the state to a~
iDdudc esar,n.- of ~lIIiainn rates
for each poUutaDt apected
40 CfR S2.21 CD (I) Iadude with filed APEN die CompliaDce with this ARAR will be
(m) foDowia8: ~
- MocIcIcd impact ualysis of
source -~
- A best awilable COIIIr01
tedmoIogy (BACI') review for
the source opcratioa.
40 CfR 52 Predict total _iaimt. of voJabIe The FS i,.di""t"'$ that "'Without
orpaic compouada (V0Ca) to ~-a~e..t. die IaDd6D gas emissioas
dem----= ~Kcinnt do DOt wiD rcs1Ik iD a release of less tbaD 1
exr.eecI4S0 Ib/br, 3,000 Ib/day, 10 pouDd pet day of total VOCs to the
pJ/day, or allowable ("lIIiuiftft abDOSpbcre.. CompliaDce with this
levels from simiJar sources usiq ARAR wiD be achiewd.
reasoubIy available coaIrOI
teclul9lo8Y (RAer).
40 CfR 61 Verify throaP ".~ CompliaDce with this ARAR wiD be
~ .tes
aDd cIispersioD ~I, that ~
hydropD sulfide em~ do DOt
c:reaIe aD ambicat COItCCIIIratioD
grater tb8D or equal to 0.10 ppIIL
-------
TABLE A.2
OOCUMfNTA11ON OF STATE ARARS WITH WlICH PCtI Al1UVfA1M! MAY BE flEQUllIED TO COMPlV
ad Mlnol ~ s.-1I8Id SII.
MInot, North "Dor. .
~ .......
Ji:';.iiOM "n!:r~1
I
"1IIIIe"'" 1We. 0._" AldeabIIIY JrI!! AIIIIIe.bIII" '0 ad MInaI ........
"'''u. Wd Deh. 8PlclIc ..... Acllon llllev8II and AppOlll18'.
W.... "'r."''' , ...1 "r:" ... ~. II nol,d ~ ,~ .vOIIIIIIII.
Pr:II:':Oft II II 0' .:1 "'..~. """a,mlnl
"a:' SU1
, ....,....... '"11
JI.1002~S ~. ...... ~.....- Acllon ~ I"RA1:r.R. A"""'.".... ..............
upon 111111 clO.... 0" c81,.
2.10.02.. =. ,.open, IIg/II. .n. Acllon Hot 811 AllAR. AdmHaIr.... ..............
.. not ARAn..
2J.2N4.oJ ""':.c" do.... ..... Acllon ""'V8I'II and appro,.lat..
po'ldo . ......."'ent..
2J.2N4.o1 08Mnf I8ndM ,*,or_. Acllon ""'-" and apprOlll18tL
81811d1rdt.
21.10..01 'ar1orll-. all... tor 1IIIdq,81 AcIIon """"'" and ....o,.I8tL
80Ikt _.11 .......
2.20..02 CIa.... all... tor --1pII1oId Acllon RaIewnt and ""OIII18tL
",8.1. ........
2J.20.12 WIt.. prot,cllorl prcN8lon.. Acllon ""'-II and .pproprtal',
21-20-1201 .,..... ... dIIr.daftr.- Acllon Hot 811 AllAR.
""""'1"'''
21-20.12-02 Or"""""'. lfIOIIfIor" """1"''''''. Acllorl """"'" ... approprtatL
11.20.12 02 WlI. .... .......d.. CtIIIfIIc8I Rete""" ... appro,.lll..
.11-10.12-04 MonIor" ... c_1fUC1Ion. Acllorl na"""" and approprlal',
IIICC 11-21-04 II""""" r.-"''' ~ Acllon =-=.:: ~. .. notact"
Ihdl8f.. ° poIIuI8nl' 11\ I.. "".. ... . 1II1II.
,.....1-11 T.",. and ~ 01.."""" Action """'" and ....oprI8Ie.
""8,,1 d III .1....081I0Il
.,...", I'."".
1.".0,.1) . ~~........ .18rId8r.. =::::e.. lllIewnI ... approprtalL
8iIiI .... W818. .....,
.1""'. oIhtr ..q,frimlnl.
2J.1.411-14 EIIIuant ......... .. "_d CtII..... =-= r.- r. AI.""".I1t I
..1IonII ~ dItdIIf...dr. Ie. I. WII . "..t,d In
,"""1Icin .,..- pel .. .. NPDE p."".
12-1..01.11 CI8Mf~..'''' cor>d8orIt at ......d Acllorl ~ ~_. t AI.........I'" 2
:;:.......~=,::= I8niJIII Ie. . WII . "..Iact In TW
","h NPUE p.."".
11.".01-21 =~~b" Acllon = tat.:". AeIm""""'" ............
.. d III 8IIrIhIIIon
.,;::'" ma 111:1 II. '''''ltcI to
fit 01"" ..cor" anot ,,,,,OII'no
.... ..nml..
llWlJRtal"lIoM
ItOCC 11.11
110 Idd w..t.
t~... ;....... A:I
~
~
-------
,
Table A-l -
- (Continued)
PERTINENT FEDERAL ARARS AND ALTERNATIVE COMPUANCE ANALYSIS
Old Minot T ""dfil1 Superfund Site
Minot, Nonh Dakota
Acdoas CitaIioD R~ ScJCc:tI'1lRemedy
Surface W.. 40 Cf'Il 264.2S1(g)(1a) -Jmat na-oa. 11M! c:oauaI- CompliaDcc wich t1Us ARAJl wiJl be
CoaUai coDcct r1IIIG« &olD a 24-baar. 25- ~
40 Cf'Il 264.%73(g)(h) ,.. stolID (... piJa, 1aDd .
tre..,..-r f,.~ 1ad&Ds).
40 Cf'Il264.301(c)(d)
40 Cf'Il 264.211(J) Pmat ovatOPPaI of -- eo-npl:."- wich this ARAJl will be
- im~ptL ac:bicwcL
~ Quality 40 Cf'Il14UI-U spcci&ca muim1llD cb-u..I CompliaD&:c wich t1Us ARAJl will be
. (O"r........... levels (Ma..s) of ac:bicwcL
public water systems for iDorpDic
aDd ~ cbeIr;aI$.
40 Cf'Il141.SO specifics maximum (O"t............ CompliaDcc wich t1Us ARAJl will be
1ew1 goals (MCLGs) of public ac:hjeved.
water systems for orgaaic
chcmu.k.
40 Cf'Il141~1 EstabJisba aaboaal rcvid ComptiaDce wich t1Us ARAJl will be
primarY driDkiDg water rcv'..nQftS ac:bicwcL
of Ma..s for ~ ~.....k.
40 Cf'Ill43JJ3 Estab1isbes ~~ ~- Compliall= wich this ARA1l will be
(0""-"'.. levels (SMC1a) for ac:bicwcL
. public water systems. '1'IIae are
fcdcra11Y noaaforccabIe staDdards
wbicb npIate ~t....-.... iD
driDkisIg water tba1 priDWiI.Y affect
its quality.
Solid WutC LaJu! 40 Cf'Il 24L1OO-212 ~1iD~- mDUmum ~ of Compliaace wich this ARA1l will be
J)isposai perfonD8DCC rcquircci of 8JJ'1 solid acbiewcL
wute IaDd ~ site ~
40Cf1l1S1 Seta forda ~ m"';"'- fedI:nl eompliaDcc wich this ARA1l will be
criteria for mUDicipll solid waste acbieved.
1aDdfiDs (MSWLFs) for CIisIiaa
aDd DeW UDits.
o .
. ,-
: .
{' .' '. - . .
. - ~.
~
-------
. 0
.
.
..
APPENDIX B
Responsiveness Summary
.. ."
. . ...~.
-------
TABL£ "-2 (Coni.)
La-IA.pllon, AIlIIIe.b18 RuII, pener" AllJlle.bIiIV 1m! Alllllclblltv to ad MInot La~
5..ncI8rdl 0' 33-11'02.0' U'I' r....em.nt. 'or I. WIS" Ch.nllc" R.,.\IInt 8IId .pproprll'.
Eller Qua., d,dlaroaa.
r 5'1" of
or1h D8ko',
Nor1h D8II0t8 33-15-18 . lI'Uemen.,C'..IIk:IIon. ,.lIlInll Chlmlc.. ReI8\11nt end 'pp'oprll.e.
AIr PoWIon to doroua. con'lnmentl.
Control fle.,...Uon,
33-15-" R..llk:1Ion1 ,.1I1Ing '0 1ugIUv. Chemic.. RellllMl .nd .ppr.II...
III' Imllllor1..
33-15-02 CmII''''' .Ir :l:.1t, .'and8;dt. Re'ellUl' 8IId .pproprllil.
..l1li11,.. Alum pern"',lbl.
concenllltlon8 0' 8Ir con'lm'nIR's.
1h11 ..cdon 1ndI<1e. .hl .Ir .o.k..
pole,.
H81ardoul Wea', Action, Hlllfdous WII" ".pllon. do no'
R.QUI.llon, ell.nllell. .ppIr line. no RellA wal" II pr...n..
Loc:allon
-------
. 0
OLD MINOT LANDFILL, MINOT, NORTII DAKOTA
RESPONSIVENESS SUMMARY
o
.
1.
OVERVIEW
The U.S. Environmental Protection Agency (EP A) established a public comment period
from January 4, 1993 through March 4, 1993 for interested parties to comment 'on the
Remediallnvestigation/Feasibility Study (RIffS) reports and the Proposed Plan for the Old
Minot Landfill Superfund site in Minot, North Dakota. EPA also held a public meeting at
7:00 p.m. on January 19, 1993 at the Minot City Hall'to outline the proposed remedy for
controlling and preventing landfill gas emissions and contaminant migration from the site.
-
The Responsiveness Snmmary, required by Superfund law, provides a summary of comments
received from the community during the public comment period, as well as EP A's responses
to public concerns. All comments received during the public comment period. were
considered in EPA's final selection of a remedial alternative for the Old Minot Landfill.
This Responsiveness Summary is organized into the following sections:
.
&c~o~don~mm~~m~~~m
.
Snmmary of Comments Received During the Public Comment Period and
EP A Responses
2.
BACKGROUND ON COMMUNl1Y INVOLVEMENT
The site was brought to the ~ttention of the North Dakota State Department of Health
(NDSDH) by a citizen's complaint in 1985. A public meeting was held, concerning the
Jandfil1~ by the Cty of Minot in Jamwy of 1990. An EPA community involvement
coordinator conducted interviews of Minot citizens during the week of September 25, 1990.
Twelve citizens were interviewed as well as the Cty Manager and Assistant Public Works
Director. Some of the citizens interviewed were business people, City Council members, the
mayor, and interested residents. The interviews took place at the business locations of the
persons interviewed and at the Minot Cty Hall. The following comments were compiled
from the EP A interviews. .' . .
Attitudes Toward EPA
The majority of interviewees expressed frustration with EP A and the Superfund program.
Their concerns were primarily economic. They also expressed resentment toward the
intrusion of outsiders into their local affairs and generally did not understand how or why
8-1
-------
their municipal landfill became involved in the' Superfund program.. There was a perception
that the Old Minot Landfill was selected as a Superfund, site simply because the EP A is
obligated to spend Superfund money in every state.
Residents felt that the EP A had lost credibility under certain circumstances and appeared
to be indecisive. They also felt that there needed to be a separate policy for municipal
landfills as they relate. to the. Superfund process. It appeared to them that municipalities,
which run their own landfills, are at a disadvantage over those who contraCt out the waste
collection and are penalized for having provided good service.
Interviewees were aware that the site h3d been listed on the National Priorities Ust (NPL).
One said he thought the situation had been well publicized. Another complained that his
only source of information was the newspaper.
Economic Issues
The majority of interviewees felt that the Superfund process was inefficient and required
unnecessary studies. One individual ,stated that too much money was being spent on the
studies rather than the cleanup. A City of MinQt official stated that Minot could clean up
the site much more inexpensively if the Superfund process would not "'mterfere."
Several interviewees felt too much time and money were spent, to do the potentially
responsible party (pRP) search. They thought it was pointless; one said that it would be
impossible to prove who put what wastes in the lan~ and another mentioned that
household waste can also contain hazardous substances.
Some felt that the cleanup was a community problem and should be funded by some kind
of taxing mech~ni~m They thought that it was unfair to charge businesses. The
interviewees generally felt that the Superfund cost recovery system was not equitable. They
argued that the businesses and the City of Minot operated the landfill in a way that was
lawful in the past, and did not consider it fair to hold them responsible now. Businesses in
the area were already hurting and the interviewees stated that the community feared losing
businesses more than paying taXes. '
On the other hand. people noted that the area was losing population and that the economy
was' depressed, suggesting that there were fewer individuals paying more taXes. . One
interviewee stated that EP A should at least pay for its own oversight. Another resident was
concemed that the bank would have a hard time selling land adjacent to the site, and the
site itself, now that it was on the NPL. '
B-2
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. 0
Environmental Impacts
. 0
The interviewees were generally uncertain of the actual environmental problems Caused by .
the landfill. They wondered how the site had ranked on the NPL and how their landfill was
different from any other small city's municipal landfill. A few were concemed that wells
may be cont~min~ted and that there was a danger of a methane fire. One person noted that
it had been an error to locate the landfill in a drainage above the river. Others asked why
a cleanup was necessary, saying that there were no families dependent on private wells for
drinJdng water, all waters in the area "test okay," and the river, downstream of the landfill,
was clean. One interviewee said the city water treatment plant was adequate.
There is a feeling of respoDSlbility to protect the water and a wimngTIess to do so if it is
really ne~. One interviewee remarked that in general the people of the area "look
after" the land, because as an agricultural community they are dependent on it. One person
expressed approval of someone (EP~) looking after the area's concerns. Several officials
stated that the city is committed to protecting the water.
Enforcement Actions
Two people felt that there had not been enough support from the state health department
with regard to setting guidelines for m~n~ging municipal landfills many years ago. They also
felt the need for a county health department. which. could check areas such as landfills
before they become a problem.
SummAI)'
The community is concerned with the cleanup primarily from an economic standpoint. The
citizens and officials generally want to clean up the site if a problem exists. The community
is also concerned about the efficiency of the EP A and the fairness of the Superfund cost
recovery process.
EPA Remonse: Due to general concem that the EP A ~ spending the community's money
on unnecessary activities, the Community Relations Program developed for the site was the
minimum permissible under law and EP A policy. While minimi7-ing costs, the Cormnunity
Relations Program is improving the community's understanding of the data and the potential
hazards concerning the site, as well as the Superfund process.
Since municipal landfills often have ~mi1~r characteristics and, consequently, lend
themselves to similar remediation technologies, EP A has developed new guidelines designed
for stre~m1ining the RIfFS and remedy selection process at Comprehensive Environmental
Response, Compensation, and liability Act (CERClA) Municipal Landfill sites. This
B-3
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streamlined approach was adopted in conducting the RI/FS at the Old Minot Landfill. Use
of the new guidelines helped to expedite the RIfFS and focus the remedy selection on
proven and widely used technologies, which ultimately resulted in a more efficient use of
time and resources. By str~~m1ining the RI/FS process EPA: (1) improves the efficiency
and effectiveness of decision J'(1~1dng at these sites; (2) provides consistency among the
Regions in their approach to conducting an RI/FS and selecting a remedy; and (3) .
facilitates more effective remedial designs. .
The community bas been kept informed of ongoing activities conducted at the Old Minot
Landfill site. through m~ilin~ newspaper announcements, and a public: meeting. In
addition, EP A has established an information repository at the Minot Public: Library where
materials relevant to the c:omnnJnity's concerns and interests may be reviewed. Documents
stored at the repository include: .
.
The RIfFS reports and related documents.
.
The Baseline Risk Assessment (BRA).
.
A Fact Sheet, summarizing the results of the risk assessment.
.
Th~ Proposed Plan.
. .
.
Transcript of public: meeting on the Proposed Plan (January 19, 1993).
3.
SUMMARY OF PUBUC COMMENTS RECEIVED DURING PUBUC COMMENT
PERIOD AND EPA RESPONSES TO COMMENTS
Comments and questions raised during the Old Minot Landfill public: c:omment period on
the RIfFS reports and proposed plan are summarized below. The comment period was held
from January 4, 1993 to March 4, 1993. The c:omments are .categorized by relevant topics.
Tedmic:al Design of the Site Remedy
.
The North Dakota State Department of Health (NDSDH) indicated that it would.
support waiving the lxl0'"7 em/sec: permeability requirement since loc:ally available
c:1ay soils could only be compacted to a permeability slightly greater than the state
standard. The State would provide such a waiver under the pr.ovisions of Section 33-
2().()1.1-10 (variance). .
Re~onse: EP A has proposed to grant a waiver from this requirement and supports
the . State's action.
B-4
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, u
.
One participant at the public meeting (January 19, 1993) asked if Alternatives 2 and
3 in the FeasIbility Study (FS) were mutually exclusive or if a passive gas collection
system could be designed with the ability to upgrade to. an active system, if ne~5sary.
Re~onse: Due to major design differences, it would be difficult to construct a gas
extraction system that could be operated as either a passive or active system. A
passive system is based on providing a pathway for landfill gas to flow from the
refuse to the atmosphere. The design essentially consists of slotted pipes buried in
horizontal trenches that allow gas to seep in and flow to vents at the surface. With
an active collection system, a vacuum is applied which induces gas to enter the
system through openings in a series of. vertical wells and discharge through a blower
stack(s). Consequently, applying suction on a passive system would be ineffective
since..air from the surface would also be drawn into the system.
.
A participant at the public meeting asked if discharging leachate to the city waste
water treatment plant could have any adverse effect on the plant and if there was any
substantial data to suppon the. evaluation.
Re~onse: The ability of the Minot waste water treatment facility to transpon and
treat leachate from the landfill was thoroughly evaluated during the RIffS. The
analysis indicated that the operation of the facility would not be adversely affected
by the leachate and that established discharge standards could be attained. This
evaluation is presented in the "Leachate Treatment Evaluation Technical
Memorandum" (SEC Donohue; July 13, 1992) and is included in the FS as Appendix
D.
.
A realtor provided an article (Newsweek; November 23, 1992) at the public meeting
that described the use of plants in cleaning up hazardous waste sites and 'Wanted to
know if this technology could be applied at the Old Minot , ~ndfil1 site.
Re$pOnse: According to the article, the application of plants in cleaning Up certain
types of hazardous chemicals is encouraging, but the research is still in the
experimental stages and is largely confined to a few types of Soil cont~minants.
Furthermore, the use of plants to collect contaminants would be ineffective in
preventing the accumulation of landfill gases and contaminated ground water beneath
. the landfill cap. Soil CODtamination at the Old Minot Landfill is not a major concern
since contaminated materials will be consolidated beneath the landfill cap. As a
result, the potential for benefiting from the use of certain plants in remedj~ting the
site is somewhat limited. .
B-5
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Scope of the Site Remedy
During the public meeting, a proposed alternative, developed and adopted by the
City of Minot, was presented by the Minot City Manager. Substantial modifications
to the City's original proposal were addressed in letters received from the City of
Minot on January 25, 1993; February 16, 1993; and March 3, 1993. Severalleners
of support for the City's plan were also received from area businesses and
orvni-mnons, the NDSDH, Senators Dorgan and Conra~ and Representative
Pomeroy.
.
The City maintained that the Baseline Risk Assessment (BRA) confirmed that the
Old Minot Landfill is a normal small town landfill an~ therefore, it should be
treated as such. The City's revised final proposal (dated March 3,1993) contained
the following elements.
(a)
(b)
(c)
(d)
(e)
, (b)
Submit all project plans and specifications to the NDSDH for review
and apprqvaL .,' :, ' .
Place and compact additional clay in areas where the cover is less than
three feet. Cap repair would be performed by City crews using City
equipment and City-owned clay material.
Remove the Deucalion gas-extraction wells and cont::tmina.ted soils
adjacent to the well locations; bury the collected soils under the cap.
ConstrUct drainage systems to control surface water runoff.
(f)
Remove any buried debris or garbage, located north of the earthen
dam at the north end of the site, and place the debris/garbage under
ther~airedcap. '
Utilize the three existing leachate sampling wells as the leachate
collection system. The three wells would be connected to a pumping
system and to the sanitary sewer system using six-inch pve sewer pipe.
If this system is not successful in reducing leachate levels in the
landfill, additional wells would be installed.. '
'(g)
Install a passive gas venting system at each of the existing leachate
sampling wells. If the passive gas system proves to be ineffective, new .
leachate collection wells would be designed to allow for installation of
an active gas collection system to solve the methane gas problem.
Relocate fencing as necessary and maintain the fence. The Minot City
Council would enact controls to prohibit: constrUction on the landfill;
B-6'
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. J
human activities at the site; and the use of ground water beneath or in
the vicinity of the J=\l1dfil1
~ .
(i)
Implement a monitoring program that would include: using existing
monitoring wells; monitoring sUIface erosion; monitoring ground water
to detect future releases of leachate; and to monitor potential impacts
to the Qty's waste water treatment facilities.
(j)'
The North Dakota State Department of Health (NDSDH) would
provide oversight for pJanning efforts, construction, and monitoring.
Remonse: With respect to the findings of the BRA, it should be noted that both
current and future risk scenarios for the site were analyzed. Under the existing
circumstances, the site does not pose any current risks to human health or the
environment. However, the risk assessment analysis also determined that there is the
potential for significant future cancer risks to the public, if remedial actions are not
implemented.
Items (a) and' (j) address the issue of oversight roles and responsibilities, but do not
specifically address the preferred alternative. The NDSDH's role in Remedial
Design (RD) and Remedial Action (RA) oversight will be established through a site-
specific enforcement agreement to be entered into by the NDSDH and EP A, prior
to RD or RA
In principle, Items (b), (c), (d), (e), (h), and (i) are consistent with the. preferred
alternative. The cap must comply with all federal and state regulations, or a waiver
must be obtained by the City. Also, the Qty's crews must be qualified to perform
the Superfund work; the equipment and material must also meet all pertinent
criteria. All of the proposed activities will be planned in more detail during the RD
phase. .
While Item (f) is, in principle, consistent with the preferred alternative, specific
decisions concerning the number of wells and types of construction material will be
developed during the remedial design process. A phased approach to well
installation may be appropriate and will be ~uated as pan of the design" efforts.
Implementation of Item (g) cannot be accomplished, from an engineering point of
view. Construction of a passive gas collection system requires that the collection
piping be placed horizontally and within the landfill mass. The passive gas collection
system, as discussed in Alternative 2 of the Proposed Plan, cannot be easily converted
to an active gas collection system due to economic and technological considerations.
Finally, it must be noted that the methane. gas is contaminated with volatile and
semi-volatile organic compounds.
B-7
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.
Two parties commented. that EP A should have considered a broader range of
altematives than the three developed in the FS. Specifically, the comments.
recommended that an alternative consisting only of appropriate institutional controls
together with comprehensive environmental monitoring be implemented at the site.
The parties felt that such an alternative remedy would be as protective in the short
term, would allow for the detection of any off-site cont~min~t migration, and would
be far less costly than the alternative selected in the Proposed Plan.
Re~onse: The RI indicated that ground water within and immediately adjacent to
the landfill, as well as gases emanating from the lan~ are cont~mina.ted. In order
to ensure that cont~mina.tion is contained at the site and isolated from potential
receptors, remedial activities are necessary. According to the National on and
Hazardous Substances pollution Contingency Plan (NCP) [40 CFR
300.430(a)(1)(iii)(D)], the use of institutional controls shall not substituie for active
measures as the sole remedy, unless such active measures are determined not to be
practicable. As a result of the FS, the proposed cleanup measures were found to be
practicable.
With regard to the ground-water monitoring suggestion, both Alternative 2 and
Alternative 3 include plans for a ground-water monitoring program.
Site Dellsting
.
A participant at the public meeting asked if there were any sites in the nation that
have been deleted from the NPL, and if cleanup of those sites was required prior to
de listing.
Several comments were also received that advocated de listing of the Old Minot
Landfill from the NPL. Justification for this request was based on the assertion that
data from the RIfFS do not support the assumptions that initially placed the site on
the NPL, and the fact that the Baseline Risk Assessment (BRA) indicated that there
was presently no risk at the site because no complete expo~e pathways were
identified for current site conditions.
Re~onse: According to 40 CFR 300.42S( e), a site may be deleted from the NPL if
no further action is appropriate. To delete a site from the NPL, one of the following
criteria must be met: .
(a)
Responsible parties have implemented all appropriate response actions
required; or
(b)
The RI bas shown that the site poses no threat to public health or the
environment and that implementing remedial measures is unnecessary.
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The Old Minot Landfill does not qualify under either of these requirements, for the
following reasons. First, the Old Minot Landfill RI definitively demonstrated that
ground water within and immediately adjacent.to the lan~;p well as lanrlfil1 gases
emanating from the landfill are currently - CODt~minated. Secondly, the BRA
determined that the site ~ pose a threat to public health orothe environment and
that significant future risks to humans may occur if remedial measures are not
implemented.
RD/RA Oversight
.
Several parties considered EP A oversight costs to date, as wen as anticipated future
ove~ght costs, to be excessive. EP A was urged to put the North Dakota State.
Department of ~ealth (NDSDH) in charge of oversight during the Remedial
Design/Remedial Action (RD /RA) phase in order to reduce oversight costs.
NDSDH commented at the public meeting and in writing that it would be willing to
, ' accept this role at the site.
Re~onse: This issue is not part of the remedy selection process and will be
investigated after the Record of Decision (ROD) is issued. EP A is actively working
to increase NDSDH's role in overseeing and implementing the cleanup activities.
NDSDH's responsibilities for oversight of the cleanup may be established through
a site-specific enforcement agreement, which would be signed by both EP A and the
State of North Dakota. .
Enforcement
.
One party expressed the concern that EPA's shon list of potentially responsible
parties (PRPs) represents a mere fraction of area businesses which contributed waste
to the landfill. The comment stated that "financial viability" appeared to be the most
significant factor in identifying PRPs to date, and urged EP A to expand the PRP
group in order to achieve a swift and fair resolution. One citizen at the public
meeting also wanted to know how many PRPs have been identified for the site at this
time.
Re~nse: EP A is continuing to research potential owners, operators, and
contributors to the landfill and will evaluatePRPs in a thorough and fair manner.
The identification of PRPs is not direCtly relevant to the Proposed Plan, and is within
the purvi,ew of EP A . .
For the RIfFS, EP A sent special' notice letters to nine PRPs and expects that
approximately the same number of special notices will be sent out for the RD/RA
phase fonowing issuance of the ROD.
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Site Risks
.
One party commented that the findings in the Baseline Risk Assessment (BRA),
which indicated that the landfill may potentially pose a future threat, were not well
documented or supportable. The party believed that the site posed neither a current
nor future threat to human health or the environment and requested that EP A revise
the BRA so as to. consider -more realistic" exposure scenarios. Supporting
documentation used in EPA's determination of potential future risk was also
requested.
Rp~nse: In accordance with 40 CFR 300.430(d)(4), EPA must use data from the
RI to conduct a baseline risk assessment to characterize the current and potential
threats to human health' and the environment. The purpose of the BRA is to'
evaluate risks that might exist if no remediation or institutional controls were applied
at the site.. The BRA is a tool that is used to assess the need for remedial action.
Since no complete exposure pathways were identified for current site-use conditions,
DO risk presently exists. However, there is a potential for land use to change and/or
cont~m;na.nts to migrate off-site in the future, resulting in the completion of currently
incomplete pathways. As a result, currently available site data were used to estimate
risks associated With hypothetical future exposures. Both average-case and worst-case
exposures (i.e., most likely exposure (MLE) and reasonable tn~Yimum exposure
(RME) scenarios, respectively) were evaluated.
The exposure scenarios developed for the site were based on the conceptual model
and incorporate the use of standardized EP A methods and assumptions in assessing
potential site-related risks. The future potentially exposed receptors who were
evaluated in the BRA consist of: (1) adult residents and occupational workers who
live or work at or in the immediate vicinity of the site, and (2) active children
betWeen the ages of 3 and 12 years who live or play in the immediate vicinity of the
site, including those who may depend on water from local shallow aquifers as their
sole source of potable water.
Specific exposure routeS that were evaluated include: the inhalation of landfill gases
and volatile cont~m;na.nts released from soU or surface waters; and ingestion or
dermal contact with ground water, soil, sediment, or surface waters. Standard EP A
. default exposure values were used in quantifying potential exposures at the site.
Exposure parameters corresponding to the national 90th percentile upper-bound
. confidence limit were used for the RME scenarios, and the 50th percentile average
value was adopted for the MI.E scenarios. Methods and values used were obtained
from the following EP A guidance documents: (1) Risk .Assessment Guidance for
Superfund (RAGS), Volume I, Part A: Human Health Evaluation Manual (1989);
(2) Human Health Evaluation Manual, Supplemental Guidance: Standard Default
Exposure Factors (1991); and (3) EPA's Exposure Factors Handbook (1989).
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Assumptions used in estimating risk are provided and discussed in the Exposure
Assessment portion (Section 3) of the BRA. A conservative approach was used in
the risk assesst1"lent to account for uncertainties and ensure adequate protection of
human health and the environment. Toxicological information used in estimating
risks was primarily obtained from the Integrated Risk Information System (IRIS;
October 1991), the Health Effects Assessment SnmmSlry Tables (HEAST; 1989), and
the Hazardous Substances Databank (HSDB; October 1991). Supporting
documentation used in developing the BRA is referenced, as appropriate, in the
report.
.
At the public meeting, a member of the commnnity asked if any citizens had
complained of potential health risks at the site since the CitY. of Minot had
performed the fencing and cap repair work.in 1989.
Re~onse: Mr. Alan Walter, Director of Public Works for the City of Minot,
responded at the public meeting that the City had not received any citizen complaints
about the site since the emergency removal work was performed.
Public Participation Process
.
EP A received several written requests for a 3O-day extension to the public comment
period.
Response: The end of the public comment period was extended from February 2,
1993 to March 4, 1993.
MiscellaDeous Questions and Comments Received at the Public Meetitlg
.
One participant at the public meeting asked if the site were to be re-scored (Le.,
Hazard Ranking Score (HRS» today, using the information currently known about
the site. would the score still be high enough to make the NPL? Another person
aSked if the site could be re-scored under the ~ Superfund Accelerated Ceanup
Model (SACM) to see if it should remain on the NPL .
Response: EP A cannot speculate on whether or not the site would still score high
enough to be placed on the NPL if it were re-evaluated today. The SACM program
does not score sites for inclusion on the NPL SACM was established to coordinate
available resources within EP A at new sites in an effort to stre:lmJine and accelerate
the Superfund process. .. .
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.
At the public meeting, one City official stated that he believed the criteria used in
the Superfund process to evaluate remedial alternatives were biased and forced the
Oty to perform an excessive cleanup under the circumstances.
Response: EP A believes that the nine evaluation criteria used to select a remedy are
not inherently biased and are valuable in comprehensively and fairly assessing the
remedial options. The nine evaluation criteria have been developed to address
CERCLA requirements and other statutory considerations as wen as technical and
policy issues. These evaluation criteria serve as the basis for conducting the detailed
analyses during the FS and for subsequently selecting an appropriate remedial action.
'Ibis detai1~d analysis is needed to evaluate the most promising alternatives selected
during the screening process and provides the decision maker with a standardized
method for comparing alternatives and developing the rationale for choosing a
preferr~d remedy.
.
One participant at the public meeting wanted to know if there was any evidence that
Site B at the Old Minot T ~ntifil1 was contamina.ted. The Minot City Attorney wanted
the record to show that the Oty of Minot disclaims any responsibility for Site B.
Response: Based on available analytical data there is no substantial evidence linking
environmental contamina.tion of surface water, ground water, or sediment with Site
B. Detections of organic compounds in surface water and ground-water samples
appear to be related to laboratory induced cont~mination, and no inorganic
compounds are significantly elevated above background levels. Low levels of several
polycyclic aromatic hydrocarbons (PAHs) were detected in a sediment sample
collected in the northeast portion of Site B, but all concentrations were estimated
and were below laboratory detection limits. It should also be noted that P AHs are
commonly found in the environment and may have resulted from the dumping of
charred lumber or the burning of wood in nearby fireplaces. During the drilling and
completion of one borehole within Site B, strong petroleum odors were . reported.
While no domestic or industrial wastes were observed during the drilling project,
constrUction debris was routinely encountered. No borings were completed below
a depth of 17 feet. .
EP A will continue to evaluate additional information, as it becomes available, and .
may initiate funher investigations if warranted. .
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