United States Office of
Environmental Protection Emergency and
Agency Remedial Response
EPA/ROD/R07-93/063
March 1993
v°/EPA Superfund
Record of Decision:
Red Oak City Landfill, IA
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4.
50272.101
REPORT DOCUMENT A 11 ON
PAGE
1'ItI8 and Subtitle
SUPERFUND RECORD OF DECISION
Red Oak City Landfill, IA
First Remedial Action - Final
~hor(8)
11. REPORT NO.
EPA/ROD/R07-93/063
~
3. A8clplent'8 Ace_Ion No.
Ii
Report Date
03/31/93
&.
7.
&
Performing OrganlDtlon Rep(. No.
II.
Performing Organization Name and Add-
10 Projact TaklWork Unit No.
11. Contr8Ct(C) or Grant(G) No.
(C)
(G)
12. ~ Organization Name 8nd Addraa8
U.S. Environmental Protection
401 M Street, S.W.
Washington, D.C. 20460
13.. Type of Report & PerIod CovIl'8cl
Agency
800/800
14.
15. Supplementary Not.
PB94-964303
1&. Ab8tract (Umlt: 200 words)
The 40-acre Red Oak City Landfill site is an inactive municipal landfill located in Red
Oak, Montgomery County, Iowa. The site borders farmland to the north and south;
parkwest Road, woodlands, and a quarry pond to the west; and the Nishnabotna River to
the east. Land use in the area is predominantly agricultural, .with manufacturing.
facilities .located within th~ City of Red Oak. The residents within the City of ~ed
Oak and south/southwest of the site use the underlying Dakota Sandstone and alluvial
deposits of the East Nishnabotna River to obtain their drinking water supply. From the
late 1940s until the early 1960s, quarry and strip mining activities were conducted at
the east edge of the site. In 1962, the City of Red Oak purchased the property and
operated it as a municipal landfill until 1974. Types of waste disposed onsite
included construction and demolition debris; tree prunings; municipal wastes; and
various industrial chemical wastes, including toluene, PCE, mineral spirits, and
laminated paper containing mercury chloride. Along with the general refuse,
approximately 8,000 pounds of drummed filter cake containing lead was disposed of
onsite. Environmental studies indicated that, as a result of past disposal practices,
'subsurface soil is contaminated sporadically with a variety of VOCs, including acetone,
(See Attached Page)
17. Document AnaIy8ia L Deacriptora
Record of Decision - Red Oak City Landfill, IA
First Remedial Action - Final
Contaminated Media: soil, debris, surface water
Key Contaminants: VOCs (benzene, PCE, TCE, toluene,
metals (arsenic, chromium, lead)
xylenes), other organics (PAHs),
b.
1cl8nl1fi8~nd8d Terms
Co
CClSATI FI8IcIIGroup
1& Availability Statement
19. Sac:urlty Class (This Rapoft)
None
3). Sac:urlty Clan (This Page)
None
21. No. of Pages
18
22. PrIce
(Sea ANSI-Z3I.18)
s..lnstfUClion8 OIl R-
OPTIONAL FORM 272 (4-77)
=:ry NTJS..35)
manI of ComIll8l'C8
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EPA/ROD/R07-93/063
Red Oak City Landfill, IA
First Remedial Action - Final
Abstract (Continued)
1-2 DCE, PCE, and toluene; and that the surficial soil contains primarily elevated levels
of PARs and heavy metals. During the RI, several "hotspots" also were identified in the
landfill. This ROD addresses the first and final action for the contaminated onsite soil,
and debris. The primary contaminants of concern affecting the soil, debris, and surface
water are VOCs, including benzene, PCE, TCE, toluene, and xylenes; other organics,
including PARs; and metals, including arsenic, chromium, and lead.
The selected remedial action for this site includes constructing a sanitary landfill cap
over the waste disposal area; contouring and revegetating the river bank slope; placing
drainage swales along the per~eter of the landfill cap to direct surface water runoff;
maintaining the cap; conducting long-ter.m ground water monitoring; and implementing
institutional controls, including deed and ground water use restrictions, and site access
restrictions, such as fencing. The estimated present worth cost for this remedial action
is $2,430,200, which includes an estimated O&M cost of $65,000 for ,years 0-5 and $45,000
for years 6-20.
PERFORMANCE STANDARDS OR GOALS:
Not applicable.
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RECORD OF DECISION
RED OAR LANDFILL
RED OAR, IOWA
prepared by:
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
REGION VII
KANSAS CITY, KANSAS
MARCH 30, 1993
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RECORD ,.OF DECISION
DECLARATION
SITE NAME AND LOCATION
Red Oak Landfill
Red Oak, Iowa
STATEMENT OF BASIS AND PURPOSE
This decision document presents the selected remedial action
for the Red Oak Landfill Superfund site, in Red Oak, Montgomery
County, Iowa, which was chosen in accordance with CERCLA, as
amended by SARA, and, to the extent practicable, the National
Contingency Plan. This decision is based on the Administrative
Record for this site.
The State of Iowa concurs with the selected remedy.
ASSESSMENT OF THE SITE
Actual or threatened releases of hazardous substances from
this site, if not addressed by implementing the response action
selected in this ROD, may present an imminent and substantial
endangerment to pUblic health, welfare, or the environment.
DESCRIPTION OF THE SELECTED REMEDY
The selected remedial action at the Red Oak city Landfill
Superfund site (herein referred to as "the Red Oak Landfill" or
"the Site") addresses all identified remedial action objectives,
and is to be implemented in a single operable unit. This action
addresses the principal threat at the site through containment of
the waste materials. The containment system will limit the
threat of direct contact with wastes, and minimize the potential
for migration of contaminants to ground water and surface water.
The major components of the selected remedy include:
.
Construction of a low permeability cover system over the
waste disposal area in accordance with Iowa sanitary
landfill closure requirements;
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.
Long-term ground water monitoring to evaluate and ensure
the effectiveness of the remedial action;
.
Installation of a fence surrounding the low permeability
cover system to control access;
.
contouring and revegetation to stabilize the river bank
slope; and
.
Institutional controls, including deed restrictions to
control future land use.
.
Inspection and Maintenance of the fencing, stabilized
slopes, and cover system to ensure long term
effectiveness.
STATUTORY DETERMINATIONS
The selected remedy is protective of human health and the
environment, complies with Federal and state requirements that
are legally applicable or relevant and appropriate to the
remedial action, and is cost effective. This remedy utilizes
permanent solutions and alternative treatment technologies to the
maximum extent practicable for this site.
Treatment of the principal threats of the site was not found
to be practicable, and the remedy does not employ treatment as a
principal element. Treatment was determined to be impracticable
primarily due to the size of the landfill, and the heterogeneity
of the wastes. Due to the size of the Site, treatment would be
cost-prohibitive for the entire volume of material that has been
disposed of at the site. It was not judged to be practical to
completely characterize surface and subsurface contaminant levels
throughout the entire landfill, to locate discrete areas of waste
to treat.
Because this remedy will result in hazardous substances
remaining onsite 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.
Administrator
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RECORD OF DECISION
RED OAK LANDFILL
RED OAK, IOWA
DECISION SUMMARY
Prepared by:
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
REGION VII
KANSAS CITY, KANSAS
KARCH 31, 1993
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TABLE OF CONTENTS
1.0 INTRODUCTION
2.0 SITE NAME, LOCATION AND DESCRIPTION
3.0 SITE HISTORY AND ENFORCEMENT ACTIVITIES
4.0 HIGHLIGHTS OF COMMUNITY PARTICIPATION
5.0 SCOPE AND ROLE OF THE REMEDIAL ACTION
6.0 SUMMARY OF SITE CHARACTERISTICS
6.1 Topography
6.2 Hydrology
6.3 Geology
6.4 Hydrogeology
6.5 Extent of Landfill Materials
6.6 River Bank Stability
6.7 Chemical Characteristics of Environmental Media
7.0 SUMMARY OF SITE RISKS
7.1 Contaminants of Concern
7.2 Exposure Assessment
7.3 Toxicity Assessment
7.4 Risk Characterization
7.5 Uncertainties
7.6 Environmental Evaluation
7.7 Conclusion
8.0 DESCRIPTION OF THE REMEDIAL ALTERNATIVES
8.1 Remedial Alternative 1
8.2 Remedial Alternative 2
8.3 Remedial Alternative 3
8.4 Remedial Alternative 4
9.0 SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES
9.1 Overall Protection of Health & Environment
9.2 Compliance with ARARs
9.3 Long-Term Effectiveness
9.4 Reduction of Toxicity, Mobility, & Volume
9.5 Short-Term Effectiveness
9.6 Implementability
9.7 Cost
9.8 state Acceptance
9.9 Community Acceptance
10.0 SELECTED REMEDY
11.0 STATUTORY DETERMINATIONS
12.0 DOCUMENTATION OF SIGNIFICANT CHANGES
ATTACHMENT A
RESPONSIVENESS SUMMARY
PAGE
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FIGURES
Figure 1:
Figure 2:
Figure 3:
TABLES
Table 1:
Table 2:
Table 3:
Table 4:
Table 5:
Table 6:
Table 7:
site Location Map
site Configuration Map
Potentiometric Surface Map
Occurrence of Constituents in Subsurface soil Samples
Occurrence of Constituents in Surface Soil Samples
Occurrence of Constituents in Ground Water Samples
Occurrence of Constituents in Ground Water Seeps
Excess Lifetime Cancer Risk
Hazard Indices for Non-Cancer Effects
Cost Summary
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DECISION SUMMARY
Red Oak Landfill
1.0
INTRODUCTION
The Record of Decision (ROD) is the final document
describing EPA's planned course of remedial action to clean up a
Superfund site, proposed or listed on the National Priorities
List (NPL). The Red Oak Landfill Superfund site consists of one
operable unit. Its focus media is soils, with a groundwater
monitoring component. This ROD for the Red Oak Landfill Site
presents the final remedy for the landfill closure through
capping.
The ROD consists of three major components: a Declaration, a
Decision Summary, and a Responsiveness summary.
The Declaration is the formal statement signed by the u.S.
Environmental Protection Agency (EPA). The Declaration functions
as an abstract for the key information contained in the ROD. The
Declaration identifies the selected remedy and states the
selection was made in accordance with the Comprehensive
Environmental Response, Compensation and Liability Act (CERCLA),
as amended by the Superfund Amendments and Reauthorization Act
(SARA), and, to the extent practicable, the National Contingency
Plan (NCP).
This document, the Decision Summary, provides an overview of
the site characteristics, the risks posed by site conditions, the
remedial alternatives evaluated, and the analysis of those
options. The Decision Summary identifies the selected remedy,
provides the rationale for the remedy selection, and explains how
the remedy fulfills statutory requirements.
The final component of the ROD, the Responsiveness Summary,
provides information about community preferences regarding the
remedial alternatives evaluated and general concerns about the
Site, the Proposed Plan, Remedial Investigation/Feasibility study
(RI/FS) report and other information in the Administrative
Record. The Responsiveness Summary also demonstrates how
comments were considered as an integral part of the decision
making process.
3
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2.0
SITE NAME, LOCATION AND DBSCRIPTION
The Red Oak Landfill site is located about 1\ miles to the
northwest of the City of Red Oak in Montgomery County, Iowa. The
site occupies a parcel of land approximately 40 acres in size on
the west bank of the East Nishnabotna River within Section 17,
Township 72N, Range 38W. The site is bounded by farmland to the
north and south, Parkwest Road and a quarry pond to the west and
the East Nishnabotna River to the east. See Figure 1 for a map of
the general vicinity and site location, and Figure 2 for a map
showing the site configuration.
Land use in Montgomery County is predominantly agricultural,
with manufacturing industry located primarily within the City of
Red Oak. Land use in the vicinity of the site is also
predominantly agricultural. The site is surrounded on the north,
west and south by a low barbed wire fence and is not open to
public use. The landfill surface is vegetated primarily with
grasses and weeds; however, wooded areas are located along the
riverbank, adjacent to Parkwest Road and along the southern
boundary of the Site. The quarry pond west of the Site is
privately owned and used for recreation, including fishing and
swimming. The water supply well field for the City is located
approximately 2 miles to the east/southeast of the Site, and
several private water supply wells are located south/southwest of
the site.
3.0 SITE HISTORY AND ENFORCEMENT ACTIVITIES
The property on which the Site is located was originally a
limestone quarry. Quarrying activities were conducted from the
late 1940's to the early 1960's. The limestone quarrying
activities started at the east edge of the site near the East
Nishnabotna River and were undertaken in a strip mining fashion.
Overburden was removed from a trench and set aside and the
limestone was subsequently excavated. FOllowing removal of the
limestone, quarrying activities were moved and a second trench
was opened. Overburden from this trench was then placed in the
bottom of the initially excavated trench. This mining procedure
was carried towards the west and ultimately halted at the west
quarry pit (see water filled quarry pond, Figure 2) in the early
1960s. A limestone rim was left in place between the quarry pit
and the west bank of the river to prevent flooding.
The City of Red Oak purchased the Site property in 1962, and
operated it as a landfill until it closed in April 1974. Wastes
disposed at the site reportedly included construction and
demolition debris, tree pruning waste, municipal refuse generated
by residents and businesses, and industrial wastes from
facilities in the Red Oak area.
4
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2000
4000
8
FIGURE 1
SITE LOCATION
1000
SCALE IN FEET
RED OAK LANDFILL
RED OAK, IOWA
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Quarry
Pond
\:,"
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---------7
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BUILDING 0
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800
200
SCALE IN FEET
APPARENT WASTE TYPE OBSERVED
I TREE TRIMMINGS AND DEMOLmON DEBRIS
t------~ MUNICIPAL AND INDUSTRIAL WASTES
FIGURE 2
SITE CONFIGURATION MAP
RED OAK LANDFILL
RED OAK, IOWA
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The industrial wastes disposed of at the site reportedly
included toluene, methyl isobutyl ketone, tetrachloroethylene,
mineral spirits, diacetone alcohol, and laminated paper
containing approximately 3 percent mercurous chloride by weight
related to Union Carbide's production of dry cell batteries.
Along with general refuse, uniroyal disposed of approximately
8,000 pounds of drummed filter cake containing approximately 430
parts per million (ppm) lead.
The site was initially identified as a result of EPA
notification by the Union Carbide corporation and Uniroyal,
Incorporated. site conditions have been investigated by EPA on
several occasions since the initial identification of the site.
Based on findings of the investigations, the Red Oak Landfill
site was included in Update Number 5 to the National Priorities
List (NPL).
The EPA subsequently notified the potentially responsible
parties (PRPs) of its intent to conduct a remedial investigation
and feasibility study (RI/FS) under CERCLA and invited their
participation in the process. In 1989, EPA and the PRPs entered
into an Administrative Order on Consent for performance of the
RI/FS, and Geraghty & Miller was enlisted to perform the work on
behalf of the PRP group.
The RI field investigation was conducted in two phases.
Phase I activities took place in December 1989 and in March
through April of 1990. Phase II activities commenced in May
1991, with river bank stability investigation activities
continuing through the Summer of 1992. The field investigation
included sampling of surface and subsurface soils/wastes, surface
water, ground water, and ground water seeps. Detailed discussion
of the results of the field investigation is contained in the RI
report. The FS report, which develops and evaluates remedial
alternatives, was completed in July 1992.
4.0
HIGHLIGHTS OF COMMUNITY PARTICIPATION
The RI/FS and the Proposed Plan for the Red Oak Landfill
site were released to the public in August 1992. These documents
were made available to the public as part of the Administrative
Record (AR) maintained by EPA's Region VII office, and the
Red Oak Public Library, located at 2nd and washington street, Red
Oak, Iowa. The remedial decision documented in this ROD is based
on information contained in the Administrative Record. The
notice of availability of these documents was published in the
Red Oak EXDress, Red Oak, Iowa, a weekly news publication, and
the Omaha World-Herald, Omaha, Nebraska, a daily newspaper
commonly read in Red Oak, Iowa.
7
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The public comment period was held from August 12, 1992
through September 11, 1992. In addition, a public meeting was
held on August 20, 1992, at the Red Oak Fire station. At this
meeting, representatives from EPA, the Iowa Department of Natural
Reources (IDNR), and the Iowa Department of Health (IDOH)
presented information and answered questions about the site and
the remedial alternatives under consideration. Comments received
during this period are addressed in the Responsiveness Summary,
which is an attachment to this ROD. A written request for an
extension of the comment period for the Red Oak Landfill Proposed
Plan was requested by the City of Red Oak, and was received by
EPA on September 1, 1992. An extension of thirty days was
granted, bringing the public comment period to a close on October
11, 1992.
5.0
SCOPE AND ROLE OF THE REMEDIAL ACTION
Response actions at the site are expected to be carried out
in a single operable unit, and no additional decision documents
are anticipated at present. The remedial action objectives for
the Red Oak Landfill site are as follows:
.
Reduce or eliminate the threat of direct contact with,
ingestion of, or inhalation of materials containing
acetone, 1,2-dichloroethene, tetrachloroethene, toluene,
and other contaminants contained in soils and wastes
buried at the site:
.
Reduce surface water infiltration through the buried
waste materials in order to minimize the potential for
leaching of contaminants from the waste materials to
ground water and surface water:
.
Control erosion of the river bank slope in order to
minimize the potential for exposure of buried waste
materials; and
.
Address potential exposure to increased contaminant
levels in the future due to erosion of existing surfacial
materials.
The selected remedial action, documented in this ROD, must
address all the remedial action objectives outlined above.
6.0
SUMMARY OF SITE CHARACTERISTICS
A summary description of the physical characteristics of the
Site, the nature of the waste materials, and the nature and
extent of contamination of ground water, surface water, and seeps
is presented below. Sources of contamination and potential
8
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routes of contaminant migration are also discussed. This summary
is based on information contained in the remedial investigation
report (Geraghty & Miller, March 1992).
6.1
Topography
The topography of the surrounding area is naturally hilly.
Intermittent stream channels dissect the farmlands located north
and south of the landfill. The topographic high of the Site is
located in the southwest corner of the property. A ridge
trending east-west is located in the southern part of the
property: the elevation of the top of the ridge dips eastward
toward the river. Slopes at the Site range from nearly flat
terrain in the northern part of the property and along the ridge
to slopes of approximately 10 percent. However, along the
eastern edge of the Site, adjacent to the East Nishnabotna River,
the slope is nearly vertical in places. Land surface elevations
range from 1,107 ft above mean sea level (MSL) in the southwest
corner of the site to 1,017 ft above MSL along the river.
6.2
Hydrology
The East Nishnabotna River flows southward along the eastern
boundary of the Red Oak Landfill site. The drainage basin of the
river upstream of the City of Red Oak covers approximately 894
square miles (USGS, 1989). The average discharge of the river
recorded for the water year of 1988 (from October 1987 to
September 1988) at the USGS gaging station located under the
Coolbaugh Street Bridge in Red Oak is 200 cubic feet per second
(cfs). High and low flows measured at the USGS gaging station
during the year of 1988 were 1000 cfs in February and 43 cfs in
September. Other perennial surface water bodies located near the
site include the 4 acre quarry pond located due west of the Site.
6.3
Geology
In general, the Red Oak area is typically underlain by
Pleistocene-aged deposits of loess and glacial till material
(drift) underlain by discontinuous, Cretaceous-aged sandstone
bedrock of the Dakota Group. The sandstone unconformably
overlies Pennsylvanian-aged limestone and shale bedrock. Where
Cretaceous-aged bedrock is absent, the glacial till is deposited
directly upon Pennsylvanian-aged bedrock.
The geology underlying the Site was evaluated using soil
boring logs, results of the geophysical survey, and available
file information. Interpretation of these data identified
several stratigraphic units underlying the Site, beginning with
the shallowest unit, as follows: landfill materials:
unconsolidated materials (likely a combination of loess, glacial
till, and alluvial deposits) reworked during the quarry
operation: undisturbed, unconsolidated materials (loess and
9
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glacial till) i undisturbed alluvial deposits: and, Pennsylvanian
aged limestone and shale. Depth to bedrock through the
unconsolidated materials ranged from approximately 40 to 90 ft.
6.4
Hydrogeology
Aquifers utilized in the Red Oak area include the Dakota
Sandstone, the alluvial deposits of the East Nishnabotna River,
and sand and gravel units within the glacial deposits. The water
supply for the City of Red Oak is derived from five wells
completed in the Dakota Sandstone. Residents living
south/southwest of the Site rely upon shallow private wells which
utilize the glacial and alluvial aquifers.
The East Nishnabotna River flows to the south and eventually
discharges into the Missouri River, and regional shallow ground
water flow is most likely southerly also. Local ground water
flow in the vicinity of the landfill is predominantly eastward
toward the river.
During monitoring well installation and soil boring
activities, several perched water zones (lenses of water
saturated materials contained within a matrix of unsaturated
materials) were encountered within the fill material. The flow
direction of perched water zones within the landfill are most
likely controlled by topography. Ground water seeps observed on
the face of the river embankment at the Site support this
hypothesis.
The East Nishnabotna River likely functions as the local
discharge boundary for shallow ground water. consistent with
this model, water levels in onsite monitoring wells indicate that
shallow ground water, within the permanently saturated materials
underlying the Site, flows east-northeast toward the river. A
potentiometric surface map is shown in Figure 2.
6.5
Extent of Landfill Materials
The extent of the fill material disposed of at the site was
evaluated based on information obtained from records review,
geophysical survey, and the soil boring program. The thickness
of the fill material encountered in the soil borings ranged from
o to 25 ft. The approximate areal extent of the fill materials
is shown on Figure 3. In general, two main areas of fill were
identified in the RI. The smaller area in the northeastern
corner of the property is composed primarily of demolition
debris, rubble, and partially burnt tree pruning waste. The
larger fill area is located in the western and southern sections
of the Site and appears to consist mainly of municipal and
industrial refuse; however, some demolition debris was also
observed.
10
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STAFF
GAGE 11
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SCALE IN FEET
LEGEND
o GMMW-1 MONITORING WELL LOCATION
.
STAFF GAGE LOCATION
1018/-" EQUIPOTENTIAL CONTOUR
FIGURE 3
1022.26
WATER ELEVATION MAY 16, 1990
POTENTIOMETRIC SURFACE MAP
MAY 16, 1990
RED OAK LANDALL
RED OAK, IOWA
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6.6
River Bank stability
Movement on the face of the slope along the southeastern
edge of the site, adjacent to the bank of t'he East Nishnabotna
River, has been observed. visual evidence of the active movement
included soil tension cracks, soil failure scarps, displaced
vegetation, and areas of no vegetation on the face of the slope.
A monitoring system of 40 survey points was installed to
quantitatively assess lateral and vertical ground surface
movements over time.
The available evidence indicates that the erosion of the
slope is due to surface water flows over the face of the slope
and/or ground water seepage that discharges from the face of the
slope. It appears, based on interpretation of historical aerial
photographs, that riv~r erosion at the toe of the river bank does
not significantly contribute to slope instability: however, this
has not yet been clearly demonstrated.
6.7
Chemical Characteristics of Environmental Media
Environmental samples from the landfill material and
surrounding media were collected and analyzed to assess current
conditions and potential environmental effects of the site. The
analytical results show that subsurface materials are
sporadically contaminated with a variety of volatile organic
chemicals (VOCs) including acetone, l,2-dichloroethene,
tetrachloroethene, and toluene. Toluene was the most frequently
detected compound. Table 1 summarizes the concentration range of
constituents detected in the subsurface materials. Polycyclic
aromatic hydrocarbons (PAH) and elevated levels of some heavy
metals were also found.
As would be expected, surficial soils were found to be
relatively free of VOC contamination: however, PAHs and above-
background levels of heavy metals were detected in the majority
of surficial soil samples. Table 2 summarizes the concentration
range of PAHs and heavy metals detected at the surface. section
4.2 in the Remedial Investigation discusses the occurrence of
"hot spots" identified in surface and subsurface soils at the
site.
Analysis of ground water samples showed the presence of
several VOCs in shallow and perched ground water at low
concentrations. Above-background levels of some heavy metals
were also detected. VOCs, semi-volatile compounds, and heavy
metals were also detected in onsite ground water seeps.
12
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TABLE 1
OCCURRENCE OF CONSTITUENTS IN SUBSURFACE SOIL
SAMPLES, RED OAR ~FILL, RED OAR, IOWA
Constituent Range
(mg/kg)
VOCs
Acetone 0.004 - 38
Benzene 0.002 - 0.015
Chloroform 0.018
1,2-Dichlorothene 0.009 - 1.4
Ethylbenzene 0.35 - 2.6
Methylene chloride 1.1
4-Methyl-2-pentanone 2.9 - 260
1, 1, 2, 2-Tetrachloroethane 1
Tetrachloroethene 0.003 - 120
Toluene 0.002 - 1,800
Trichloroethene 3.1
styrene 0.75 - 1.5
Vinyl chloride 0.021 - 0.15
Xylene 0.65 - 2
13
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TABLE 2
OCCURRENCE OF CONSTITUENTS IN SURFACE SOIL
SAMPLES, RED OAK LANDFILL, RED OAK IOWA
,.
CONSTITUENT RANGE
(mq/kq)
Inoraanics
Aluminum 4,400 - 11,000
Arsenic 4.1 - 9.3
Barium 120 - 380
Beryllium 0.6 - 1
Cadmium 4.3 - 18
Chromium 11 - 17
Cobalt 5.5 - 8.5
Copper 15 - 140
Iron 15,000 - 23,000
Lead 8.7 - 440
Manganese 400 - 15,000
Mercury 0.08 - 5.5
Nickel 16 - 25
Selenium 0.3
Silver 1.1 - 4.5
Thallium 0.6
Vanadium 25 - 31
Zinc 75 - 2,800
-
VOCs
Tetrachloroethene 0.11
SEMI-VOCs
Bis (2-ethylhexy) phthalate 0.098 - 240
Dibenzofuran 0.065
Di-n-butYlphthalate 0.067 - 0.14
Di-n-octvlphthalate 0.18
cPAH(f) 0.46 - 2.4
tPAH(g) 0.081 - 7.3
MISCELLANEOUS
Cyanide 0.1 - 0.1
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Concentration ranges of constitiuents detected in ground
water and surface seeps are summarized in Tables 3 & 4.
Analysis of surface water and sediment from the East
Nishnabotna River, both upstream and downstream of the Site,
indicate that the river is not being measurably impacted by the
Site. Given the concentrations of contaminants found in the
shallow ground water and ground water seeps, and the discharge
rates of ground water and seeps to the river, measurable impacts
on the river would not be expected under current conditions.
7.0
SUMMARY OF SITE RISKS
A baseline risk assessment was conducted as required by
CERCLA to evaluate the potential impacts to human health and the
environment posed by site contaminants absent any remedial
action. The baseline risk assessment provides the basis for
taking action and indicates the exposure pathways that need to be
addressed by the remedial action. Both current and hypothetical
land use scenarios were evaluated. This section summarizes the
findings of the risk assessment, which is contained in the
Administrative Record as part of the RI report. The risk
assessment consists of an identification of contaminants of
concern, an exposure assessment, a toxicity assessment, and a
risk characterization.
7.1
contaminants of Concern
Identification of the contaminants of concern was
accomplished after considering the fOllowing factors: (1)
comparison of mean detected concentrations to media-specific mean
background concentrations, (2) comparison of average detected
ground water and surface water concentrations to potentially
applicable or relevant and appropriate standards or criteria, (3)
frequency of detection of a given contaminant, and (4) toxicity
of the contaminants.
7.2
Exposure Assessment
This assessment addressed the potential for exposure to the
inorganics, VOCs, and semi-volatiles detected in the ground
water, surface water, soils and sediments at the Red Oak
Landfill. In order for risk to exist, the potential for a
receptor to be exposed to contaminated environmental media must
exist. Exposure can only occur if there is both a source of
chemical release and a mechanism of transport to a receptor
population.
The exposure assessment identified potential pathways and
routes for contaminants of concern to reach the receptors and the
estimated contaminant concentration at the points of exposure.
Exposure pathways by which humans could be exposed to chemicals
of concern were identified based on reasonable assumptions about
current and future uses of the Site.
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TABLE 3
OCCURRENCE OF CONSTITUENTS IN GROUND-WATER
SAMPLES, RED OAK LANDFILL, RED OAK, IOWA
CONSTITUENT RANGE
(mq/kq)
Inoraanics
Arsenic 0.0011 - 0.0074
Barium 0.029 - 0.83
Beryllium 0.0001 - 0.0003
Cadmium 0.0011 - 0.0037
Chromium 0.026
Cobalt 0.0081 - 0.014
Copper 0.0062 - 0.018
Iron 0.049 - 22
Magnesium 18 - 64
Manganese 0.024 - 8.1
Nickel 0.0038 - 0.75
Selenium 0.0027 - 0.026
Silver 0.0059 - 0.0061
Vanadium 0.0041 - 0.015
Zinc 0.026 - 0.054
VOC
Acetone 0.008 - 0.008
1,2-Dichloroethene 0.004
4-Methyl-2-pentanone 0.011 - 0.04
Toluene 0.025 - 0.065
16
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TABLE 4
OCCURRENCE OF CONSTITUENTS IN SURFACE WATER SAMPLES
FROM ON-SITE SEEPS, RED OAK LANDFILL, RED OAK, IOWA
CONSTITUENT
Inoraanics
Aluminum
Arsenic
Barium
Beryllium
Chromium
Cobalt
Copper
Iron
Lead
Magnesium
Manganese
Nickel
Vanadium
Zinc
VOCS
1 , 2 Dichloroethene
4 -Me thy 1-2 -pentanone
Tr ichl or oethene
Toluene
Tetrachloroethene
Vinyl Chloride
8EMI-VOCS
Benzyl alcohol
Isophorone
2 -Methy Iphenol
4 -Methy Iphenol
Naphthalene
RANGE
(mg/kg)
0.17 -
0.0014 -
0.097 -
0.0003 -
0.061
0.026
0.015
0.32
0.0014
5.6
0.013
0.0021
0.0095
0.11
260
0.022
3.8
0.017
0.31
0.18
0.22
270
0.12
160
16
0.41
0.58
0.61
0.2
1.3
35
0.085
3.9
6
0.96
0.22
0.01
0.007
0.008
0.2
0.031
0.004
0.02
17
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For each potentially significant exposure pathway, exposure
assumptions were made for reasonable maximum exposures. A
reasonable maximum exposure (RME) represents a situation which is
more conservative than an average case, but is not a worst case
scenario. The RME scenario is developed to reflect the types and
extent of exposures that could occur based on likely or potential
uses of the site.
The primary exposure pathways with significance for current
conditions at the Red Oak Landfill site include dermal contact,
inhalation, and incidental ingestion of contaminated soils and
fugitive dust. Due to hydrologic conditions at the site, i.e.
shallow ground water gradient toward the river, ingestion or
other exposures to contaminated ground water were determined not
to represent a significant exposure pathway.
The potential current exposures were evaluated using a
hunter/trespasser scenario. The risk assessment assumed that a
hunter/trespasser weighing 70 kilograms walked across the site
for 2 hours per day, 100 days per year, for 30 years.
Hypothetical future exposures were evaluated for an excavation
worker and residential scenarios. Exposure assumptions for the
excavation worker included a 70 kilogram adult exposed 8 hours
per day, 5 days per week, for 6 weeks. The residential exposure
scenario assumed a combined 30 year exposure period as a child
and as an adult.
7.3
Toxicity Assessment
Slope factors (SFs) have been developed by EPA's
Carcinogenic Assessment Group for estimating excess lifetime
cancer risks associated with exposure to potentially carcinoge~ic
contaminants. SFs, which are expressed in units of (mg/kg-day) ,
are multiplied by the estimated intake of a potential carcinogen,
in mg/kg-day, to provide an upper-bound estimate of the excess
lifetime cancer risk associated with exposure at that intake
level. The term "upper bound" reflects the conservative estimate
of the risks calculated from the SF. Use of this approach makes
underestimation of the actual cancer risk highly unlikely. Slope
factors are derived from the results of human epidemiological
studies or chronic animal bioassays to which animal-to-human
extrapolation and uncertainty factors have been applied. The
uncertainty factors account for the use of animal data to predict
effects on humans.
Reference doses (RfDs) have been developed by EPA for
indicating the potential for adverse health effects from exposure
to contaminants exhibiting noncarcinogenic effects. RfDs, which
are expressed in units of mg/kg-day, are estimates of lifetime
daily exposure levels for humans, including sensitive
individuals, that are likely to be without an appreciable risk of
adverse health effects. Estimated intakes of contaminants from
environmental media (e.g., the amount of a contaminant ingested
from drinking contaminated water) can be compared to the RfD to
judge whether the contaminated media is likely to present a human
18
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health concern. RfDs are derived from human epidemiological
studies or animal studies to which uncertainty factors have been
applied.
7.4
Risk Characterization
For carcinogens, risks are estimated as the inGremental
probability of an individual developing cancer over a life-time
as a result of exposure to the carcinogen. Excess lifetime
cancer risk is calculated in the following manner:
Risk = CDI x SF
where:
risk = a unitless probability of an individual developing cancer;
CDI = chronic daily intake averaged over 70 years or other period
of exposure (mgjkg-day); and
-1
SF = slope factor, expressed as (mgjkg-day)
These risks are probabilities that are generally expressed
in scientific notation (e.g., 1X10-6 or 1E-6). An excess
lifetime cancer risk of 1X10-6 indicates that, as a reasonable
maximum estimate, an individual has a 1 in 1,000,000 chance of
developing cancer as a result of site-related exposure to a
carcinogen under the specified exposure conditions. The lifetime
cancer risks associated with exposure to the Red Oak Landfill
Site are summarized in Tables 5. The hypo~hetical child resident
scenario presents the highest risk at 2x10 .
The potential for noncarcinogenic effects is evaluated by
comparing an exposure level over a specified period of time
(e.g., life-time) with a reference dose derived for a similar
exposure period. The ratio of exposure to toxicity is called a
hazard quotient (HQ). The Hazard Index is generated by adding
the HQs for all contaminants of concern that affect the same
target organ within a given medium or across all media to which a
given population may reasonably be exposed.
The HQ is calculated as follows:
HQ = CDIjRfD
Where:
CDI = Chronic Daily Intake
RfD = reference dose; and
CDI and RfD are expressed in the same units and represent the
same exposure period (i.e., chronic, subchronic, or short-term).
In general, HIs greater than one are associated with
potentially increased health risk. The baseline risk assessment
indicated total HIs ranging from less than 1 to a maximum of 8
19
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for hypothetical child resident. Hazard Indices calculated for
the various exposure scenarios are summarized in Table 6.
TABLE 5
EXCESS LIFETIME CANCER RISK
RED OAK LANDFILL, RED OAK, IOWA
Scenario RISK
Hunter/Resident 4XlO.s
Excavation Worker 5XlO-7
Future Adult Resident-soil Exposure lXlO-4
Future Child Resident-soil Exposure 2XlO-4
TABLE 6
HAZARD INDICES FOR NON-CANCER EFFECTS
scenario Hazard Index
Hunter/Trespasser 0.2
Excavation Worker 1.0
Future Adult Resident-soil Exposure 1.0
Future Child Resident-soil Exposure 8.0
20
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7.5
Uncertainties
The risk assessment process, in general, uses various
assumptions regarding exposures and chemical toxicities to
estimate risks. Inherent in this estimation of risk is
considerable uncertainty.
Environmental sampling itself introduces uncertainty,
largely because of the nonhomogeneous nature of most media. It
is not known how well the chemical data collected during sampling
efforts at the Red Oak Landfill reflect actual site conditions.
As with most dump sites, the uncertainty is especially large in
the waste disposal due to the heterogeneity and inaccessibility
of the wastes. As discussed in section 4.2 of the Remedial
Investigation, the contaminants present, as well as their
concentrations, vary considerably with location and depth within
the disposal area. The estimates of exposure point contaminant
concentrations used in the risk assessment may not be
representative of actual site conditions. The use of 95 percent
upper confidence level or maximum detected level for exposure
point concentration estimates reduces the likelihood that these
levels were underestimated. However, potential exposure in the
waste disposal area, especially for the hypothetical excavation
worker scenario, may be higher than estimated in this assessment.
Also, the risk assessment process involves the usage of a
subset of all Site contaminants (contaminants of concern) to
estimate risks and does not account for the effects of all Site
contaminants.
In addition to the limitations associated with a limited
number of chemical data points, other assumptions and
uncertainties that affect the accuracy of the risk assessment
result from the extrapolation of potential adverse human effects
from animal studies, the extrapolation of effects observed at
high dose to low dose effects, the mOdeling of dose response
effects, and route-to-route extrapolation. These extrapolations
are generally carried out with the intent to err on the side of
conservatism, but the limited number of possible data points and
the heterogeneity of the materials at the site contribute to the
need to be conservative in selecting a remedy.
The estimation of chemical intakes is dependant on the
exposure scenarios used. The exposure assumptions therefore,
introduce additional uncertainties. Also, it should be kept in
mind that all plausible exposure scenarios have not been
evaluated, and further, the scenarios that were evaluated assume
that site conditions remain stable over time. As such, these
risk estimates should be viewed in consideration of the various
assumptions and uncertainties upon which they are based.
21
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7.6
Environmental Evaluation
The environmental risks posed by the site are judged to be
minimal under current conditions. The most likely impacts would
be to the aquatic ecosystem; however, the levels of contaminants
detected in ground water and ground water seeps indicate that the
rate of off-site migration of contaminants is too small to date
to have measurable impacts on the East Nishnabotna River.
Samples taken from the River support this conclusion, since
constituents detected in the East Nishnabotna River were similar
in both upstream and downstream segments. Constituents detected
in sediments were similar to those found in samples t~ken from
background locations. EPA believes, however, that further harm
could result if the landfill materials were exposed as a result
of erosion or other disturbance of the existing landfill surface
or adjacent river bank.
7.7
Conclusion
Based on the results of the risk assessment and the
additional factors discussed here, the EPA has determined that
actual and threatened releases of hazardous substances from this
Site, if not remediated, may present an imminent or substantial
endangerment to public health, welfare, or the environment.
8.0
DESCRIPTION OF THE REMEDIAL ALTERNATIVES
Information gathered during the Remedial Investigation was
used to review possible remedial methods and to develop several
remedial alternatives. A Feasibility study was then conducted to
evaluate the effectiveness of the alternatives in addressing the
concerns related to the Red Oak Landfill site.
In the Feasibility study, EPA considered four remedial
alternatives. The major components of each alternative are
described below.
8.1
Remedial Alternative 1
. No Action
Under Remedial Alternative 1, the Site would remain in its
current condition and no further action would be taken to prevent
exposure to site contaminants or reduce migration of
contaminants. The NCP and the Superfund process require that the
"No Action" alternative be evaluated. This alternative provides
a baseline against which all other alternatives are compared.
This alternative is not protective of human health and the
environment in the long-term due to potential for further
degradation and potential exposures to on-site visitors and
residents.
22
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8.2
Remedial Alternative 2
. Access control
. Deed restrictions
. Ground water monitoring
Access restrictions would be provided by the installation of
a fence around the perimeter of the site. For purposes of the
Feasibility study, it was assumed that the fence would be a 6-
foot high chain link fence with 3 strands of barbed wire along
its top. However, a fence of other construction which serves to
prevent access to the Site by unauthorized personnel would also
be acceptable. A sufficient number of warning signs would be
placed along the perimeter fence. A Site inspection and
maintenance program would be instituted to maintain the condition
of the fence as well as to monitor the condition of the landfill
cover, bank stability, landfill seeps, etc.
Deed restrictions would be imposed through the local
authorities and would be recorded in the appropriate registry of
deeds. Deed restrictions would control any future land
development of the Site. In addition, deed restrictions would
prevent the future placement of ground-water supply wells within
a prescribed zone on and adjacent to the site.
A ground water monitoring program would be implemented to
identify and quantify any waste constituent releases that may
occur from the landfill waste materials. The program would
generally follow the substantive provisions of the State of
Iowa's sanitary landfill post-closure ground water monitoring
requirements identified under 567 lAC 103. The exact scope of
the long-term monitoring program, in terms of the number and
location of monitoring points, the frequency of monitoring, and
the parameters to be analyzed for, would be developed during the
remedial design phase.
For purposes of the Feasibility study, it was assumed that
the five existing ground water monitoring wells would initially
be sampled semi-annually, then annually during the course of a
thirty year monitoring period. Samples would be analyzed for
VOCs, selected metals and water quality indicators. Each round
of ground water sampling data would be analyzed to determine
whether a statistically significant change in values has occurred
for any of the constituents of concern. In accordance with
CERCLA section 121(c), a formal review of the ground water
quality data would be conducted by the EPA within five years of
the implementation date.
Alternative 2 would take less than 6 months to construct.
The capital costs associated with implementing Alternative 2 are
estimated to be $162,800. The annual O&M costs are estimated to
be $30,000 for the first 5 years, and 20,000 for the subsequent
25 years. By applying a 5% discount rate over a 30-year
implementation period, the total present worth associated with
Alternative 2 is estimated to be $513,600.
23
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~
8.3
Remedial Alternative 3
. Access control
. Deed restrictions
. Ground water monitoring
. Sanitary landfill cap
. River bank stabilization
. Long term operation and maintenance
of cap
Alternative 3 would consist of placing a sanitary landfill
cap over the existing landfill surface. The access and
institutional controls identified for Alternative 2 would also be
provided under this alternative. In addition, the active river
bank slope in the southeastern portions of the site would be
contoured and revegetated/reforested to manage surface water
runoff and reduce soil erosion.
subtitle D of the Resource Conservation and Recovery Act
(RCRA) allows States to develop programs for the management of
solid waste. In accordance with Subtitle D of RCRA, the state of
Iowa has promulgated regulations for management of solid waste
landfills. Some of these regulations are more stringent than the
corresponding Federal regulations for management of solid waste
appearing at 40 CFR Part 258. The State is authorized to
administer the solid waste management program in Iowa. The State
solid waste regulations are potential ARARs.
The Iowa solid waste management regulations are not
applicable to the Red Oak Landfill site, since solid waste was
not disposed of at the site subsequent to the effective date of
December 3, 1986. However, the operation and characteristics of
the Red Oak Landfill site are typical of sanitary landfills that
received solid waste from a variety of sources. The Iowa
regulations for management of solid waste under 567 lAC 103 and
567 lAC 110 are relevant and appropriate for the selection of
remedy at the site because the site is sufficiently similar to
sites at which Iowa solid waste regulations would apply.
The function of the engineered sanitary landfill cap under
Alternative 3 would be to limit the amount of water infiltration
that passes down through the landfill waste material, and to
properly manage surface water runoff and direct,surface water
away from the slopes adjacent to the river. In addition, a key
function of the cap is to provide a physical barrier to prevent
exposure through direct contact with the waste material.
At a minimum, the engineered sanitary landfill cap would be
designed and constructed to meet the substantive provisions of
567 lAC 103, which requires a two-foot minimum compacted soil
cover and a two-foot minimum uncompacted soil cover to support
vegetation. The State regulations require a minimum slope of 5
percent, not to exceed 25 percent, and installation of permanent
survey markers. State regulations which are administrative in
nature, including reporting requirements, are not included as
components of Alternative 3. '
24
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Areas beyond the extent of buried waste may be graded, as
needed, to manage and promote surface water runoff. To account
for the additional surface drainage that would result from the
reduced permeability of the landfill cover, drainage swales would
be placed along the perimeter of the landfill cap, as necessary,
to direct the surface runoff to existing intermittent stream
channels located to the north and south of the landfill area.
The surface drainage patterns would also be designed to direct
surface runoff away from unstable river bank areas.
A long-term ground water monitoring program would be
designed and implemented in a manner similar to that described
under Alternative 2. New components of the ground water
monitoring network would be designed and constructed in
accordance with substantive requirements under 567 lAC 110. The
exact scope of the long-term monitoring program, in terms of the
number and location of monitoring points, the frequency of
monitoring, and the parameters to be analyzed for, would be
developed during the remedial design phase.
It is estimated that the sanitary landfill cap construction
could be completed within a 6 to 12-month period. The capital
costs associated with implementing Alternative 3 are estimated to
be $1,695,100. The annual O&M costs are estimated to be $65,000
for the first 5 years, and $45,000 for the subsequent 25 years.
By applying a 5% discount rate over a 30-year implementation
period, the total present worth associated with Alternative 3 is
estimated to be $2,430,200.
8.4
Remedial Alternative 4
. Access control
. Deed restrictions
. Ground water monitoring
. Hazardous waste landfill cap
. River bank stabilization
. Long term operation and maintenance
of cap
Alternative 4 would be similar to Alternative 3, except
a RCRA Subtitle C cap would be used to cover the existing
landfill surface rather than a sanitary landfill cap. Apart
some differences in the design of the cap, all aspects of
Alternative 4 would be identical to those described for
Alternative 3.
that
from
Regulations have been promulgated under RCRA Subtitle C for
closure of hazardous waste landfills. The regulations allow for
clean closure, where all contaminated materials are removed and
managed as hazardous wastes, and landfill closure, which has
certain minimum requirements for the design of the final cover
system. These regulations under Subtitle C are not applicable to
the remedy at the Red Oak site since no hazardous wastes were
placed in the landfill subsequent to the effective date of the
regulations, November 19, 1980, and the remedy does not
constitute treatment, storage, or disposal of a hazardous waste.
25
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To determine the relevance and appropriateness of the
subtitle C closure requirements, the characteristics of the waste
and the site are considered. The site received some industrial
wastes such as lead-contaminated filter cake, spent solvents, and
paint wastes, but most of the materials disposed of at the site
can be described as municipal solid wastes, tree pruning waste,
and construction and demolition debris. Solid waste rather than
hazardous waste regulations normally apply to the latter types of
materials. Solid waste requirements are appropriate despite the
presence of hazardous substances in the landfill, since solid
waste landfills typically contain household hazardous wastes and
hazardous wastes from certain classes of small quantity
generators.
A RCRA Subtitle C type cap generally provides additional
material layers to the sanitary landfill type cap further
reducing the amount of infiltration that could pass through the
cap. In accordance with 40 CFR 264.310 and EPA Technical
Guidance (USEPA 1989b), the RCRA subtitle C cap would typically
include a two-component low permeability barrier consisting of a
clay layer overlain by a flexible membrane liner.
A long-term ground water monitoring program would be
designed and implemented in a manner similar to that described
under Alternatives 2 and 3. New components of the ground water
monitoring network would be designed and constructed in
accordance with substantive requirements under 567 IAC 110. The
exact scope of the long-term monitoring program, in terms of the
number and location of monitoring points, the frequency of
monitoring, and the parameters to be analyzed for, would be
developed during the remedial design phase.
It is estimated that the hazardous waste landfill cap could
be constructed within 18 to 24 months. The capital costs of
implementing Alternative 4 are estimated to be $2,415,100. The
annual O&M costs for this alternative are estimated to be $65,000
for the first 5 years, and $45,000 for the subsequent 25 years.
By applying a 5% discount rate over a 30 year implementation
period, the total present worth associated with Alternative 4 is
estimated to be $3,150,200.
9.0
SUMMARY OF THE COMPARATIVE ANALYSIS OF ALTERNATIVES
This section summarizes the comparative analysis of
alternatives presented in the Feasibility Study Report.
Nine evaluation criteria have been developed by EPA to
address CERCLA statutory requirements and technical, cost, and
institutional considerations which the Agency has determined
appropriate. The evaluation criteria serve as the basis for
comparing remedial alternatives. These criteria are defined
below.
Threshold criteria:
1) Overall Drotection of human health and the environment:
Alternatives are assessed to determine whether they provide
adequate protection of human health and the environment based on
26
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how risks posed through each exposure pathway are eliminated,
reduced, or controlled, through treatment, engineering controls,
and/or institutional controls.
-
2) Compliance with a?plicable or relevant and appropriate
requirements (ARARs): This criterion addresses whether a remedy
will meet all of the applicable or relevant and appropriate
requirements of Federal and State environmental statutes or
provides a basis for invoking a waiver of these requirements.
primary Balancing criteria:
3) Long-term effectiveness and permanence: This criterion is a
measure of the ability of a remedy to maintain reliable
protection of human health and the environment over time, once
cleanup goals have been met. This criterion includes the
consideration of residual risk and the adequacy and reliability
of controls.
4) Reduction of toxicity. mobility. or volume throuqh treatment:
This refers to the anticipated performance or degree of
effectiveness of the treatment technologies that a remedy
employs.
5) Short-term effectiveness: This refers to the period of time
needed to complete the remedy and is a measure of any adverse
impacts on human health and the environment that may be posed
during the construction and implementation of the remedy. The
amount of time needed until protectiveness is achieved is also an
assessment factor.
6) Implementability: This criterion requires an assessment of
the technical and administrative feasibility of implementing a
remedy, including the difficulties associated with construction
and the availability of services and materials.
7) Cost: Under this criterion the benefits realized by
implementing a remedy are weighed against the cost of the remedy.
Generally, this criterion is only used to distinguish between
alternatives that are equivalently protective.
MOdifying Criteria:
8) state acceptance: Technical and administrative concerns the
state may have with regard to an alternative are considered in
the remedy selection process.
9) Community acceptance: Community issues or concerns with
regard to the proposed cleanup plan and other remedial
alternatives are considered in the remedy selection process.
9.1
Overall Protection of Human Health and the Environment
All of the alternatives, except the no action alternative,
are protective of human health and the environment by controlling
risk through containment of the wastes and/or usage of
institutional controls. Since the no action alternative does not
eliminate, reduce, or control any of the potential exposure
27
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pathways, it is not considered protective of human health and the
environment, and will not be considered further in the analysis
of potential remedies for the site.
..
The fence and institutional controls provided under
Alternative 2 is considered protective because the potential for
direct contact with the wastes would be limited and contaminants
are not currently migrating offsite in large enough
concentrations to impact human health and the environment.
However, Alternative 2 relies on institutional rather than
engineering controls and does not protect against the possibility
of increased offsite migration of contaminants and increased
exposure of waste materials due to further degradation of
landfilled materials and/or uncontrolled river bank erosion.
Alternatives 3 and 4 provide a level of protection superior
to that of Alternative 2. The cap would act as a physical
barrier to direct contact with the waste materials. Also, the
cap would reduce infiltration through the waste materials,
leading to reduced offsite migration of contaminants and
minimizing the potential for increased offsite migration of
contaminants in the future. Cap design goals under Alternative 4
would require lesser permeability than that required under
Alternative 3, and therefore, Alternative 4 is considered to rank
slightly higher in overall protectiveness than Alternative 3.
9.2 complianoe with Applioable or Relevant and Appropriate
Requirements
Alternative 2 does not comply with state of Iowa landfill
closure regulations. Therefore, alternative 2 does not comply
with ARARs.
The primary potential ARARs for Alternatives 3 and 4 include
the hazardous and solid waste landfill closure requirements. The
state of Iowa has promulgated regulations which provide for
management of solid wastes in accordance with RCRA Subtitle D.
The State regulations constitute potential ARARs for the Red Oak
Landfill remedy selection.
state regulations for the closure of solid waste landfills
under 567 IAC 103 and 567 IAC 110 are relevant and appropriate to
the Red Oak Landfill remedy selection. Alternative 3 can be
designed in compliance with the substantive provisions of these
regulations. The landfill cover included as a component of
alternative 4 exceeds the cap design requirements under the State
solid waste regulations. Therefore, Alternatives 3 and 4 would
both be in compliance with the State of Iowa solid waste landfill
closure regulations. Hazardous waste landfill closure
requirements under Subtitle C of RCRA do not constitute ARARs for
the selected remedy at the Red Oak Landfill site because the
wastes were deposited before the enactment of RCRA (not
applicable) and are generally not "sufficiently similar" to RCRA
wastes that the regulations be adhered to as a matter of policy
(not relevant and appropriate).
The state regulation concerning cleanup actions which is set
forth in 567 IAC 133, which is applicable here, requires that
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certain action be taken when the action levels specified in 567
lAC 133.2 are exceeded in groundwater. This could require that
the lifetime health advisory level (HAL) or the negligible risk
level (NRL) be met by requiri~g a groundwater cleanup. However,
the regulation provides that where, as here, site conditions and
available technology are such that attainment of these goals
would be impractical, an alternative cleanup level or levels may
be established, including such other conditions as will
adequately protect the public health, safety, environment and
quality of life. As part of this remedy, institutional controls
will be established to control usage of groundwater contaminated
at levels in excess of action levels prescribed in 567 lAC 133.
Although they do not constitute ARARs, Maximum contaminant
Levels (MCLs) established under the Safe Drinking Water Act will
be considered in the selection of remedy at the Red Oak Landfill
site. MCLs are directly applicable at the tap only when the
water is provided to 25 or more people or 15 or more service
connections. The MCLs are not considered relevant and
appropriate since the shallow groundwater at the site does not
represent a potential drinking water source. The site is located
directly adjacent to the western bank of the East Nishnabotna
River. The shallow ground water beneath the site flows east to
northeast, discharging directly into the River.
Three rounds of shallow ground water samples were collected
from the five on-site monitoring wells during the RI.
Additionally, shallow ground water samples were collected from
two nearby residential wells.
Five volatile organic compounds (VOCs) were detected in
samples collected from the onsite wells. None of the detected
VOC's exceeded corresponding MCLs. No semi-volatile compounds
were detected.
Significant inorganic compounds detected in samples
collected from the on-site wells (at greater than twice the
background concentration) include arsenic, barium, cadmium,
cobalt, copper, manganese, and nickel. All inorganic
concentrations detected were below the corresponding MCLs, with
the exception of nickel in one sample. Nickel exceeded the MCL
only once during three sampling events for all of the five
monitoring wells. No lead, mercury or cyanide were detected in
any of the samples.
Analyses of the private well samples detected no organic or
inorganic constituents exceeding the corresponding MCLs.
With the exception of a single exceedence for nickel, all
organic and inorganic contaminant levels were below the
corresponding MCLs. In addition, it does not appear that the
site contaminants are adversely impacting water quality in any
drinking water wells. comparison of the current data to the MCLs
further supports the risk assessment, which indicates that ground
water remediation is not a necessary component of the selected
remedy.
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9.3
Long-Term Effectiveness and Permanence
Alternative 2 is not considered reliable in the long-term
due to the inability to assure the continued effectiveness of
institutional controls, and the difficulty for EPA to enforce
institutional controls directly. Alternative 2 also lacks
engineering controls designed to assure that the site remains
stable over time, and that exposure to surface or subsurface
contaminants does not increase due to erosion or other
disturbance of surface materials. Moreover, the National
Contingency Plan states that "the use of institutional controls
shall not substitute for active response measures" such as
containment of source material in cases where such active
response measures are practical (40 CFR 300.430(a) (1) (iii) (D».
Alternatives 3 and 4 would provide much greater long-term
effectiveness than Alternative 2. Installation of a cap would
minimize the potential for direct contact with the waste
materials, and greatly reduce the potential for contaminant
migration throughout the life of the cap, which is largely
dependant on how well and for how long the cap is maintained. It
is difficult to predict any differences between the two capping
alternatives with regard to durability over the long-term.
9.4
Reduction of Toxicity, Mobility or Volume through Treatment
The application of treatment technologies was not found to
be practical for this Site, and therefore none of the
alternatives involve treatment.
9.5
Short-Term Effectiveness
Of the available alternatives, Alternative 2 ranks the
highest in short-term effectiveness because it can be implemented
quickly and easily with no impacts to worker health and safety
from potential exposure to waste materials.
Construction of either of the capping alternatives would
require scarification and regrading of the existing landfill
cover leading to the potential for exposure to waste materials
. and contaminant release during the implementation period.
Therefore, Alternatives 3 and 4 could lead to potential short-
term impacts on human health and the environment which would not
be a concern for Alternative 2. Alternative 4 is slightly less
effective in the short-term than Alternative 3, since it would
likely require a slightly longer construction period.
9.6
Implementability
Alternative 2 may be readily implemented. The capping
alternatives require a much more involved design and construction
effort, and would be somewhat more difficult to implement than
Alternative 2. Factors influencing the implementability of the
capping alternatives include the local availability of materials,
and the potential for encountering cap construction difficulties
along the river bank. It is anticipated that both Alternatives 3
and 4 could be implemented without excessive difficulties:
however, Alternative 4 is considered slightly more difficult to
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implement than Alternative 3 due to the additional material
requirements and the added complexity of installation.
9.7
Cost
Table 7 presents a summary of the capital costs, present net
worth operation and maintenance (0 & M) costs, and the total net
present-worth costs estimated for each of the alternatives.
There are no costs associated with implementation of the no-
action alternative.
9.8
state Acceptance
The Iowa Department of Natural Resources (IDNR), acting on
behalf of the state of Iowa, has indicated a preference for
Alternative 3, but finds Alternatives 2 and 4 to be marginally
acceptable.
TABLE 7
COST SUMMARY
O&M Cost Total
capital (present Present
Cost Net Worth) Net Worth
Alternative 2 $162,800 $350,800 $513,600
Access Restrictions
Alternative 3 $1,695,100 $735,100 $2,430,200
Sanitary Landfill CaD
Alternative 4 $2,415,100 $735,100 $3,150,200
RCRA CaD
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9.9
community Acceptance
Community acceptance of the available remedial alternatives
was evaluated following the public meeting held on August 20,
1992, and the conclusion of the public comment period on October
11, 1992. The results of this evaluation are presented in the
attached Responsiveness Summary.
10.0
THE SELECTED REMEDY
Based upon consideration of the requirements of CERCLA, the
detailed analysis of alternatives using the nine criteria, and
public comments, the EPA and the IDNR have determined that
Alternative 3 is the most appropriate remedy for the Red Oak
Landfill site. Alternative 3 provides the best balance of trade-
offs among the alternatives with respect to the evaluation
criteria.
The primary component of the remedy will be placement of an
engineered low-permeability cap over the surface of the landfill.
The function of the cap will be to limit the amount of water
infiltration that passes through the landfill waste material, to
provide a physical barrier limiting the potential for direct
contact with the waste materials, and to properly manage surface
water runoff to prevent ponding, infiltration, and erosion.
To manage surface drainage resulting from the reduced
permeability of the landfill cover, diversion and drainage
structures will be placed along the perimeter of the landfill
cap, as necessary, to direct surface runoff to existing
intermittent stream channels located to the north and south of
the landfill area. The surface drainage patterns will also be
designed to direct surface runoff away from unstable river bank
areas.
Contouring and revegetation/reforestation techniques will be
employed to stabilize the river bank slope in the areas currently
exhibiting active soil movement due to precipitation runoff and
ground water seepage from the face of the slope. These actions
should reduce or eliminate seepage from the face of the slope and
allow direction of surface water runoff away from the slope. The
effectiveness and success of the landfill capping and
contouring/revegetation technologies in stabilizing the river
bank will be monitored through regular inspection. If
inspections indicate that soil movements on the face of the slope
have not been adequately stabilized, or if erosion continues to
be a problem, additional response actions will be taken.
It is unclear whether river erosion at the toe of the river
bank contributes to the instability of the slope. The results of
slope stability monitoring and study of river channel migration
over time currently appear to indicate that significant toe
erosion has not occurred. After controlling precipitation runoff
and ground water seepage in the manner described above, the
influence of toe erosion on the stability of the river bank will
be further evaluated over time. Operation and maintenance plans
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will address monitoring and evaluating the effects of river
erosion on bank stability in conjunction with a contingency plan
for actions to prevent river erosion and stabilize the toe of the
slope.
A long-term ground water monitoring program will be designed
and implemented using existing and/or new monitoring wells for
purposes of detecting and characterizing potential ground water
contamination and evaluating the effectiveness of the remedy.
Monitoring plans will contain a strategy for establishing and
monitoring contaminants of concern, maximum permissible
contaminant levels, and points of compliance. The selected
remedy will also include a field study conducted during the
design phase to determine the necessity for a landfill gas
ventilation or collection system.
A perimeter fence will be constructed to control access to
the landfill area. Institutional controls, including deed and
access restrictions, will be used to control future land use at
the site. Institutional restrictions will also be established to
control usage of ground water contaminated at levels in excess of
action levels prescribed in 567 lAC 133.
11.0
STATUTORY DETERMINATIONS
Consistent with the statutory requirements of section 121 of
CERCLA, as amended, remedial actions should be selected that:
.
Are protective of human health and the environment.
.
Comply with ARARs.
.
Are cost effective.
.
utilize permanent solutions and alternative treatment
technologies to the maximum extent practicable.
satisfy the preference for treatment which, as a
principal element, reduces toxicity, mobility, or
volume.
.
The manner in which the selected remedy satisfies these
five requirements is discussed in the following subsections.
11.1
PROTECTION OF IIUHAN HEALTH AND THE ENVIRONMENT
The selected remedy is protective of human health and the
environment in that it minimizes all potential risks posed by the
Red Oak Landfill. The landfill cover system, in conjunction with
fencing and land use restrictions, will limit the potential for
exposure to waste materials through direct contact, which is the
primary health risk identified at the,Site.
The landfill cover system will also minimize the amount of
infiltration passing through waste materials, thus, reducing the
potential for leaching of waste constituents which could
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discharge as seeps or enter the underlying ground water.
controlling ground water usage will further reduce the potential
for exposure to contaminated ground water.
The contouring and drainage systems in conjunction with
river bank stabilization will limit erosion of the river bank and
cover soils, minimizing the potential for losing containment of
the waste materials.
11.2 COMPLIANCE WITH APPLICABLE OR RELEVANT AND APPROPRIATE
REQUIREMENTS
The selected remedy will comply with all applicable or
relevant and appropriate requirements (ARARs). The ARARs,
presented below, are categorized as location-specific, action-
specific, or contaminant-specific. All actions associated with
the selected remedy are considered onsite actions and, therefore,
need only comply with the substantive requirements of Federal and
state environmental laws that are determined to constitute ARARs.
11.2.1
Location-specific ARARs
Location-specific ARARs are restrictions placed on the
concentration of hazardous substances or the conduct of
activities solely because they are in a specific location.
Analysis for these requirements included a review of the
Archeological and Historic Preservation Act, the Archeological
Resources Protection Act, the Endangered species Act, the Fish
and wildlife Coordination Act, the Clean Water Act, the Resource
Conservation and Recovery Act, and Iowa waste management laws.
Location standards for disposal facilities are specified
under RCRA 40 CFR 264.l8(b), and 40 CFR 258, Subpart B. These
standards apply to the siting of new facilities and therefore
will not be applicable to the Red Oak Landfill; however, the
restriction on facilities located in a lOO-year floodplain is
considered relevant and appropriate. Both municipal waste
landfills and hazardous waste management facilities located
within a lOO-year floodplain should be constructed, operated, and
maintained to prevent washout of any waste by a lOO-year flood.
The selected remedy will not impact historic, archeological,
or cultural resources, sensitive ecosystems or any threatened or
endangered species. No other location-specific requirements were
determined to be either applicable or relevant and appropriate.
11.2.2
Action-specific ARARs
Action-specific ARARs are technology- or activity-based
requirements or limitations on actions taken as part of the
remedy. Analysis for these requirements involved a review of the
environmental laws and regulations that pertain to closure of a
land disposal facility including the Solid Waste Disposal Act,
the Resource Conservation and Recovery Act, and the Iowa waste
management laws.
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The wastes at the Red Oak Landfill were disposed of prior to
the effective date of landfill closure requirements under RCRA
subtitles C and D and the Iowa Solid Waste Disposal Act, as
amended. In addition, the selected remedial action does not
constitute treatment, storage ~r disposal of solid or hazardous
waste; therefore, landfill closure requirements under RCRA or the
Iowa Solid Waste Disposal Act are not applicable to this action.
The National Contingency Plan provides that the nature of
the wastes, and the type and size of the facility should be
considered in judging the relevance and appropriateness of a
given requirement. The Red Oak Landfill operated as a large
municipal landfill. The site did receive some industrial wastes,
such as lead filter cake, spent solvents and paint wastes.
However a large majority of the materials disposed of at the site
included municipal refuse, tree pruning waste, and construction
and demolition debris. This is supported by subsurface sampling
conducted during the remedial investigation that confirmed the
sporadic presence of hazardous substances, generally at low
concentrations. The presence of low levels of hazardous
substances is not atypical of Subtitle D facilities which receive
household hazardous wastes and other hazardous wastes from
certain classes of small quantity generators. The overall
composition of the materials disposed of at the Red Oak Landfill
therefore more closely resembles solid waste regulated by
Subtitle D of RCRA than hazardous waste regulated by Subtitle C
of RCRA.
Other factors are also considered in the determination of
relevance and appropriateness, such as the type and size of the
facility. The Red Oak Landfill is approximately 40 acres in
size, and was operated primarily as a municipal waste landfill.
These are typical characteristics of a Subtitle D facility. In
addition, materials disposed of at the Red Oak Landfill are not
currently adversely impacting surface or ground water quality.
For these reasons, Subtitle C regulations for landfill closure
are not considered relevant and appropriate to the Red Oak
Landfill remedy selection.
The State of Iowa is authorized to administer the solid
waste management program in Iowa. The State solid waste
regulations replace the corresponding Federal regulations under
Subtitle D of RCRA as potential ARARs. The.operation and
characteristics of the Red Oak Landfill site are typical of
sanitary landfills that received solid waste from a variety of
sources. Because the Iowa solid waste regulations would
otherwise be applicable to the site if disposal had occurred
subsequent to the effective date of the Iowa regulations, the
Iowa regulations for management of solid waste under 567 lAC 103
and 567 lAC 110 are relevant and appropriate for the selection of
remedy at the site.
The specific regulations constituting ARARs contained in 567
lAC 103 and 110 include sanitary landfill post-closure monitoring
requirements at 567 lAC 103.2(10), closure requirements at 567
lAC 103.2(13), and the postclosure requirements for 30 years
following closure of the site at 103.2(14). In addition, ARARs
impacting the design of the ground water monitoring system
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include requirements for hydrologic monitoring systems at 567 IAC
103.2(3) and 567 IAC 103.2(4), and monitoring well siting
requirements at 567 IAC 110, and monitoring well design
requirements at 567 IAC 110.11. The selected remedy will comply
with the substantive provisions of the above mentioned
requirements which have been determined to constitute ARARs.
11.2.3
contaminant-specific ARABs
Contaminant-specific ARARs are health- or risk-based
numerical values that establish the acceptable amount or
concentration of a chemical that may be found in, or discharged
to, the ambient environment.
The EPA has proposed, but not promulgated, New Source
Performance Standards (NSPSs) under the Clean Air Act (CAA) for
air pollutant emissions from new municipal solid waste landfills.
An environmental requirement can only constitute an ARAR if
promulgated. Given the similarity of the Red Oak landfill to the
municipal solid waste landfills to be regulated by this new rule,
these requirements are to be considered (TBCs) for the selected
action.
Iowa's ambient air quality standards (567 IAC 28), derived
from the National Primary and Secondary Ambient Quality Standards
(NAAQS) provided in 40 CFR Part 50, are considered relevant and
appropriate to the evaluation of air quality at the Site both
during and after implementation of the remedy. The restrictions
at 567 IAC 23 will be applicable to fugitive dust emissions
generated during the construction phase.
Federal Water Quality Criteria (WQCs) and Iowa Surface Water
Quality criteria are considered relevant and appropriate for
evaluating water quality in the East Nishnabotna River. Although
analysis of river water samples taken during the remedial
investigation have not shown measurable impacts on river water
quality, monitoring plans will include river sampling and
analysis to verify that these criteria are not exceeded during
and after implementation of the selected remedy.
11.3
cost-Effectiveness
The selected remedy is. considered cost effective in that it
affords overall effectiveness proportional to its costs. The
selected remedy is the least costly of the two alternatives that
are deemed to provide adequate protection of human health and the
environment.
11.4
utilization of Permanent Solutions and Alternative
Treatment Technologies to the Maximum Extent Practicable
The EPA has determined that the selected remedy utilizes
permanent solutions and treatment technologies to the maximum
extent practicable for this Site. The fact that the selected
remedy does not employ treatment, reflects the finding that no
remedies involving treatment are practicable for this Site.
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As with the majority of landfills and large dumpsi~es, cost-
effective remedial actions with potential application for the Red
Oak Landfill site must involve containment technology as a
primary component. Treatment. of the principal threats of the
site was not found to be practicable, and the remedy does not
employ treatment as a principal element. Treatment was
determined to be impracticable primarily due to the size of the
landfill, and the heterogeneity of the wastes. Due to the size
of the Site, treatment would be cost-prohibitive for the entire
volume of material that has been disposed of at the site. It is
not was not judged to be practical to completely characterize
surface and subsurface contaminant levels throughout the entire
landfill, to locate discrete areas of waste to treat.
The selected remedy provides the best balance among the
alternatives with respect to the evaluation criteria identified
in section 9 of this ROD. Since Alternative 2, which employs
institutional controls and access restrictions only, is not
considered to provide reliable long-term protection, capping is
considered the only alternative that is both adequately
protective and cost-effective. Alternative 3 is preferred over
Alternative 4 because it is equally effective in preventing
direct contact with the waste materials, which has been
identified as the primary threat posed by the site, but costs
less to implement. Also, analysis of relevant landfill closure
requirements indicates that sanitary landfill requirements are
appropriate for the Site.
11.5
Preference for Treatment as a principal Element
Treatment of the principal threats of the site was not found
to be practicable; therefore, the selected remedy does not
satisfy the statutory preference for remedial actions which
employ treatment as a principal element. The large size of the
landfill, the large volumes of wastes, the dispersion of the
contamination, and the heterogeneity of the wastes, are all
factors precluding a remedy in which contaminants could be
excavated and treated effectively.
12.0
DOCUMENTATION OF SIGNIFICANT CHANGES
The Proposed Plan for the Red Oak Landfill Site was released
for public comment in August 1992. The Proposed Plan identified
Alternative 3, sanitary landfill closure, as the preferred
remedial action. The EPA has reviewed all written and verbal
comments submitted during the comment period, and has determined
that no significant changes to the remedy, as originally
identified in the Proposed plan, are necessary.
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RECORD OF DECISION
RESPONSIVENESS SUMMARY
RED OAK LANDFILL SITE
RED OAK, IOWA
Prepared by:
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
REGION VII
KANSAS CITY, KANSAS
MARCH 31, 1993
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TABLE OF CONTENTS
1.0 INTRODUCTION
2.0 COMMUNITY PARTICIPATION ACTIVITIES
3.0 SUMMARY OF PUBLIC COMMENTS AND AGENCY RESPONSES
3.1
Comments Received At The Public Meeting
3.2
Written Comments Received During Public Comment Period
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1.0 INTRODUCTION
This Responsiveness Summary is the third and final component
of the Record of Decision (ROD) for the Red Oak Landfill site.
The Responsiveness Summary provides information about community
preferences regarding the remedial alternatives evaluated and
general concerns about the site. The Responsiveness Summary also
demonstrates how comments were considered as an integral part of
the decision-making process. section 2.0 describes the community
participation activities that were conducted as part of the
remedy selection process. section 3.0 includes a summary of
comments received from the community during the public comment
period, including those received from any potentially responsible
parties (PRPs). EPA's response to each comment is provided.
2.0 COMMUNITY INVOLVEMENT
The RIfFS and the Proposed Plan for the Red Oak Landfill
site were released to the public in August 1992. These documents
were made available to the public as part of the Administrative
Record maintained by EPA's Region VII office. An additional copy
of the Red Oak Landfill site Administrative Record has been made
available locally at the Red Oak Public Library, located at 2nd
and Washington Street, Red Oak, Iowa. The remedy selection
documented in this ROD is based on information contained in the
Administrative Record. The notice of availability of these
documents was published in the Red Oak Excress, Red Oak, Iowa, a
weekly news publication, and the Omaha World-Herald, Omaha,
Nebraska, which is a daily news publication with circulation
available to Red Oak residents.
The public comment period was originally announced from
August 12, 1992 through September 11, 1992. In addition, a
public meeting was held on August 20, 1992, at the Red Oak Fire
station. At this meeting, representatives from EPA, and the Iowa
Department of Health (IDOH) presented information and answered
questions about the site and the remedial alternatives under
consideration. Comments received during this period are
addressed in the Responsiveness Summary, which is an attachment
to this ROD.
An extension of the comment period for the Red Oak Landfill
Proposed Plan was requested by the City of Red Oak, and was
received by EPA on September 1, 1992. An extension of thirty
days was granted, bringing the public comment period to closure
on October 11, 1992.
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3.0
RESPONSE TO COMMENTS
3.1
RESPONSE TO COMMENTS RECEIVED AT THE PUBLIC MEETING
Comment: One commentor questioned whether the proposed fence
would surround the entire property, or only the contaminated
area. The commentor questioned how the fence would be
constructed and maintained, and whether noxious weeds would be
allowed to revegetate the site.
Response: There is no need to surround the entire property. In
order to achieve cost-effectiveness, the fence will surround only
areas covered by the sanitary landfill cap, providing for some
buffer area to be determined in the remedial design phase.
The exact design of the fence will be determined following
selection of remedy, during the detailed design phase. As
discussed above, the interests of the community will be
considered by EPA in the final design. The selected remedy
includes maintenance of the fence to maintain its effectiveness.
The selection of indigenous vegetation will be determined
during the design phase fOllowing remedy selection and will
consider the need to control noxious weed growth.
Comment: One commentor asked what evidence EPA had regarding
pollutant migration, what the current cost estimate for the
proposed remedy is, to whom the costs will be charged, who will
be responsible for operation and maintenance, and if
consideration has been given to relocation of the entire
landfill.
Response: There is evidence of contaminant migration because of
the low levels of contaminants detected in the ground water, and
because of the presence of surface seeps originating from buried
materials. These data have been presented in the Remedial
Investigation which is included in the site Administrative
Record.
The current estimated cost of the selected remedy is $2.43
million. The EPA would look toward those deemed to be
potentially responsible parties to actually implement the
cleanup. Operation and maintenance may be provided through an
agreement reached with the potential responsible parties as a
component of the selected remedy: otherwise, the EPA would look
to the state of Iowa to provide long-term operation and
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maintenance if the Superfund pays for the cleanup.
Excavation and off-site management of the landfilled
materials has been judged to not be economically feasible due to
the tremendous volume of material that would require management
and the associated costs.
Comment: One commentor asked if the remedy would prevent
contamination of the Red Oak, Iowa municipal water supply.
Response: On the basis of existing data, the municipal water
supply does not appear threatened. The selected remedy will
further reduce the potential for contamination of ground water in
the area.
Comment: One commentor asked the number of sites appearing on
the EPA's National Priorities List, where else the proposed
remedy had been implemented, whether testing had been performed
on an active well immediately northwest of the site, if testing
had detected contaminants from the site in any private wells or
the nearby quarry pond, and when the remedy would be implemented.
Response: The number of sites appearing on EPA's National
Priorities List exceeds 1200. The selected remedy at the Red Oak
Landfill site is a common remedy selection for former municipal
landfills that received hazardous substances nation-wide. Remedy
selection is, however, conducted on a site-by-site basis.
All analytical results generated during the Remedial
Investigation are included in the Administrative Record. The
analysis of samples collected from the quarry pond detected the
presence of five metals. The quarry pond does not appear to be
threatened by contaminants at the site.
Two private wells were sampled during the investigation.
without more specific information it is not possible to state if
the specific well mentioned had been sampled. If private wells
are identified during the remedial design phase that appear to be
threatened by contaminants at the site, they will be included in
the ground water monitoring program.
The schedule for implementation of the remedy is dependent
upon negotiations with potentially responsible parties following
remedy selection, but could be completed in as short a time frame
as one and one-half to two years.
Comment: One commentor raised concerns regarding the impediment
the fence would cause with wildlife traffic patterns, and the
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direction that surface water runoff would be diverted from the
site. The commentor asked if consideration has been give to some
type of system to collect and contain the seeps before they enter
the river.
Response: Protection of wildlife will be considered during the
design of the fence. The surface drainage direction will be
determined during the remedial design phase. The selected remedy
will control infiltration of precipitation through the surface,
and is expected to help to reduce or eliminate the presence of
the seeps. This in conjunction with river bank stabilization
measures should help to control the seepage problem. If the
remedy is fully effective, collection and containment of these
seeps will not be necessary.
Comment: One commentor asked if the ground water would be
threatened if the seeps were dried up.
Response: The threat to the river and any threat to ground water
would both be controlled by limiting infiltration of
precipitation into the landfill. With less water entering the
landfill, there will be less leachate likely to be generated.
Comment: One commentor asked what assurance existed that the
remedy would be effective, and who was involved in the remedy
selection process.
Response: These types of remedies have been successfully and
effectively implemented by not only EPA, but states,
municipalities, and private entities at numerous sites of a
similar nature nationally. Although there can never be absolute
certainty that any remedy will be effective, in EPA's judgement
this is effective, and should provide long-term protection of
human health and the environment. EPA makes the actual remedy
selection, with input from the state and public. The state of
Iowa concurs with EPA's selected remedy.
Comment: One commentor asked why access and institutional
controls and ground water monitoring (alternative 2) alone would
not be preferred over the selected remedy, and why the selected
alternative is preferred over alternative 4, placement of a RCRA
cap.
Response: The selected remedy provides the best balance across
the nine criteria EPA uses for decision-making, as specified in
Federal regulations. Long-term protectiveness can not be assured
with alternative 2 due to long-term uncertainty in the
effectiveness and implementability of institutional controls:
the risk of erosion or other disturbance of existing surficial
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materials resulting in further exposure to hazardous substances;
and the continued potential for direct contact with surface
soils. The selected remedy also controls infiltration into the
landfill which addresses the threat to surface and ground water
posed by the continued migration of contaminants.
The selected remedy also better satisfied the nine remedy
selection criteria than alternative 4. In particular, the
selected remedy was determined to be more cost-effective than
alternative 4. Although both the selected remedy and alternative
4 were determined to be protective, the selected remedy afforded
similar protection at a lower cost.
Comment: One commentor asked for a breakdown of estimated costs
for the selected remedy. The commentor believed that some of the
costs may have been over-estimated. The commentor asked if there
was anything that would cause EPA, on the basis of existing
information, to broaden the preferred alternative. The commentor
asked about the health hazard posed by this site, and the threat
to wildlife posed by the site. The comment or again reiterated
concern that the fence should be designed to provide access to
wildlife. The commentor asked how the cost of the remedy would
be apportioned.
Response: This information was provided for the audience at the
public meeting, and is included in Table 14 in the Remedial
Investigation which appears in the site Administrative Record.
The costs represent order-of-magnitude cost estimates, which are
considered to be accurate to within -30% to +50% The estimated
costs will be refined during the design phase.
The remedy selected for the Red Oak Landfill site is the
same alternative presented the Proposed Plan as EPA's preferred
alternative. The preferred alternative will be implemented as
presented. The remedy can not be significantly altered or
expanded in scope without a supplemental remedy selection
process, possibly requiring issuance of a revised proposed plan,
as well as an additional public comment period and another
opportunity for a public meeting. The EPA does not intend to
revise the selected remedy at this time.
A risk assessment was performed to estimate current and
future potential health risks at the site. The risk assessment
concluded that there was an unacceptable level of risk under
certain future use scenarios. However, additional risks may
exist due to the presence of undetected contaminants at the
surface of the landfill, and increased future risk would result
if surficial materials are eroded or disturbed and additional
contaminants at higher concentrations are exposed. The EPA has
concluded that the selected remedy is. appropriate and necessary
for the protection of public health and the environment.
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The EPA will first attempt to arrange for an agreement to
implement the selected remedy with the parties deemed potentially
responsible for the contamination according to the Superfund law
(Comprehensive Environmental Response, Compensation, and
Liability Act, as amended). The details of the apportionment of
costs would likely be determined through negotiations among the
potentially responsible parties following remedy selection. If
an agreement for the implementation of the remedy can not be
concluded with potentially responsible parties, then under the
law, Superfund trust fund money could be used to fund up to half
of the remedy, since the site is municipally owned, and the
remaining half would need to be funded by the City or the State.
If Superfund monies are used to fund a portion of the remedy, it
would be EPA's intention to pursue cost-recovery through
litigation with any non-settling potentially responsible parties
later on.
Protection of wildlife will be considered during the design
of the fence, as stated above.
Comment: One commentor believed that a six-foot chain link fence
would be excessive for some deer to jump over, and could result
in bodily harm to some animals.
Response: This will be considered in the design of the fence.
Comment: One Commentor expressed the City's concern for
minimizing the cost of the remedy, and asked for assurance that
the City would not be required to pay for half of the remedy.
Response: The EPA is sensitive to the City's concern for the cost
of the remedy. According to the comprehensive Environmental
Response, Compensation, and Liability Act, as amended, remedies
selected by EPA at Superfund sites must be cost-effective. Cost
is one of the criteria that EPA considers in conjunction with
performance to determine the cost-effectiveness of each of the
remedies. The EPA has selected a cost-effective remedy for the
Red Oak Landfill site. The apportionment of costs among the
parties may be reached through negotiations as part of a
settlement between EPA and the potentially responsible parties,
or would need to be shared by EPA and other levels of government
as discussed above.
3.2
RESPONSE TO WRITTEN COMMENTS
Comment: The commentor requested a 30-90 day extension of the
public comment period in order to provide adequate time to
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prepare his replacement in the position of city Attorney prior to
his departure.
Response: A 30 day extension was granted and the comment period
was extended to October 11, 1992. A written response was sent
to the requestor.
Comment: The commentor concurred that a sanitary landfill cap is
necessary to limit potential migration. The commentor requested
that no more extensive fencing be installed than what is
currently in place. This would benefit wildlife, and be less
costly to maintain and would not be an eyesore.
Response: Fencing is normally an integral component of the
selected remedy to control future access to the site and to
protect the landfill cover. During the design of the remedy,
including the required fencing, consideration will be given to
both aesthetics and protection of wildlife.
Comment: The commentor provided comments on behalf of the City
of Red Oak, Iowa. The City believes that the cost of Alternative
3 should in no event exceed the $2.43 million estimate, and that
many of the costs for components of alternative 3 were over-
estimated. The City urges EPA not to broaden the scope of the
proposed plan, and that local contractors be used to the greatest
extent possible. The City is not so much concerned about the
site's hazards to wildlife, as the disruption of wildlife traffic
patterns caused by a unnecessarily high or dense fence. Standard
farm fence would be sufficient. Regrading and revegetation
should be accomplished to possibly provide a wildlife habitat or
future recreational use.
Response: The estimated costs outlined in the Feasibility Study,
Table #14, are considered order-of-magnitude cost estimates, that
will be refined during the design phase of the project. The
order-of-magnitude cost estimate is intended to be accurate
within +30% - 50%.
The remedy selected for the Red Oak Landfill site is the
same alternative presented the Proposed Plan as EPA's preferred
alternative. The preferred alternative will be implemented as
presented. The remedy will not be significantly altered or
expanded in scope without a supplemental remedy selection
process, including issuance of a revised proposed plan, an
additional public comment period and an opportunity for a public
meeting. The EPA does not intend to revise the selected remedy
at this time.
Fencing and wildlife protection will be considered as
discussed above. Revegetation of the site is an integral
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component of the selected remedy. The future use of the site
must remain protective of human health and the environment. Any
potential future use of the site must not threaten the continued
effectiveness of the cover system installed as a component of
this remedy.
If implementation of the remedy is funded through use of the
Federal Superfund trust fund, procurement of contractor services
must be conducted in accordance with federal acquisition
regulations. Although preference can not legally be given to a
group of potential bidders on the basis of their proximity to the
site, local contractors are expected to be given the opportunity
to submit proposals for the work to be performed, and compete for
the contracts to implement the selected remedy. If the remedy is
implemented through some type of unilateral or consental
enforcement activity, EPA may have limited control over
contractor selection.
The EPA is sensitive to the City's concern for the cost of
the remedy. According to the Comprehensive Environmental
Response, Compensation, and Liability Act, as amended (CERCLA),
remedies selected by EPA at Superfund sites must be cost-
effective. Cost is one of the criteria that EPA considers in
conjunction with performance to determine the cost-effectiveness
of each of the remedies. The EPA has made the determination that
the selected remedy for the Red Oak Landfill site is cost-
effective.
COMMENT: . Another commentor felt that a landfill cap and
associated controls, as proposed, was the most effective and
economical remedy for the site. The commentor also expressed
interest in participation in the implementation of the remedy.
RESPONSE: Potential contracting opportunities for local firms are
addressed above.
COMMENT: One commentor provided comments on behalf of the Red
Oak Landfill Respondents. This commentor concurred with EPA's
proposed remedy. The commentor believes that access control
objectives can be accomplished with a 3 to 4 strand barbed-wire
fence. The commentor believes that access restrictions alone are
adequately protective in the northern portion of the site that
received only tree pruning waste and other demolition debris.
The commentor believes that the remedial design should consider
identification of cost-effective borrow sources, including on-
site materials, and should provide for minimal disruption to the
community due to construction traffic. The commentor agrees that
ground water monitoring and management of precipitation runoff at
the site are important components of the remedy. The commentor
recommends details for a ground water monitoring program.
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RESPONSE: Design of the fence will be addressed following remedy
selection in consideration of the comments received regarding
aesthetics and wildlife. The EPA believes that the existing data
are inadequate to conclude that hazardous substances exceeding
health-based levels do not exist in the northern portion of the
landfill. In fact, due to the areal expanse of the site, it is
not practical to consider completely characterizing surface and
subsurface concentrations across the entire site. The selected
remedy includes a cover for the entire landfill area to provide a
barrier and prevent infiltration to all potentially contaminated
areas.
Cost-effectiveness and disruption to the community will be
considered during the design of the remedy. Innovative
approaches are sometimes identified by bidders and other
interested parties during the design phase. The ground water
monitoring program recommended by the comment or will be
considered during the design phase of the project.
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