United States Office of
Environmental Protection Emergency and
Agency Remedial Response
EPA/ROD/R04-92/115
September 1992
PB93-964021
&EPA Superfund
Record of Decision:
Madison County Sanitary
Landfill, FL
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NOTICE
The appendices listed in the index that are not found in this document have been removed at the request of
the issuing agency. They contain material which supplement, but adds no further applicable Wormatton to
the content of the document All supplemental material is, however, contained in the administrative record
for this site.
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REPORT DOCUMENTATION 11. REPORT NO. 1 ~ 3. Reclplenra AccauIon No.
PAGE EPA/ROD/R04-92/115
4. 1IUe and SubtltJa 5. Report Date
SUPERFUND RECORD OF DECISION 09/28/92
Madison County Sanitary Landfill, FL
6.
First Remedial Action - Final
7. Author(a) I. PIIrfonnlnll Organization RepL No.
8. P8rfonnlng Orgalnlzatlon Nama and Add- 10. ProjecllTaak/Work Unit No.
11. Contracl(C) 0' Gtant(G) No.
(C)
(G)
12. Sponaorfng Otganlzatlon Nama and Add- 13. Type of Report. P8,lod ColHlrail
U.S. Environmental Protection Agency 800/000
401 M Street, S.W.
Washington, D.C. 20460 14.
15. Supplemantary Hotea
PB93-964021
18. Abatract (Umlt: 200 worda)
The 90-acre Madison County Sanitary Landfill is an active landfill area located in
Madison, Madison County, Florida. Adjacent to the site is other county land, including
the County Department of Transportation and the County's aviation hangar and landing
strip. The landfill surface is covered with native soil that wa~ originally excavated
from the trenches in preparing cells to receive waste. Vegetative cover is absent over
most of the inactive or recently closed waste cells; however, over older closed cells,
vegetative cover is present. In 1970, the City of Madison began operating the Madison
County Landfill as a sanitary landfill. The landfill, which was operated as an unlined
trench and fill operation, was divided into several areas. The Yard Trash Area,
located in the southeastern portion of the landfill, was primarily used to dispose of
large bulk debris usually associated with construction and demolition activities as
well as drums containing industrial wastes. The alleged Acid Disposal Area, located in
the southern portion of the property, was reportedly used to dispose of acid wash
water. . From 1971 to 1980, domestic waste from the city and surrounding area as well as
local industrial wastes were disposed of in the landf ill. During that time, the ITT
Thompson Industries (formerly a division of ITT Corporation) disposed of waste in the
(See Attached Page)
17. Documanl AnaJyaIa L DaacrfplOr8
Record of Decision - Madison County Sanitary Landfill, FL
First Remedial Action - Final
Contaminated Media: soil, gw
Key Contaminants: VOCs, other organics, metals
b. IdanllfJ8r81Open-Endad Tanna
Co COSA TI Fl8ld1Grvup
11. Availability Slatament 18. Secu,1ty CI... (Thla Report) 21. No. of Pall"
None 88
20. Secu,1ty CIaaa (Thla Page) 22. Price
None
272 (4-77)
50272-101
(Saa AHSI-Z38.18)
Saa '_clio,.. on Re".,.
(Formerty NTls.35)
Departmant of Comrrerce
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EPA/ROD/R04-92/115
Madison County Sanitary Landfill, FL
First Remedial Action - Final
Abstract (Continued)
landfill, including 55-gallon drums filled with waste pOlishing/buffer compounds at the
site, but the exact' location of disposal is not known. From 1971 to 1974, ITT Thompson
arranged for the disposal of acid, which was reportedly taken to the landfill. The type
of wastes disposed of included acid wash water that may have contained chromic acid with
maximum concentrations of chromium 50 ug/l. No information on the pH of the acid wash
water or the quantity disposed was available. No other known wastes were disposed of in
that area. Currently, approximately 40 tons of waste per day are disposed into the one
group of remaining active onsite waste cells; however the state is in the process of
closing the landfill to any receipts of waste. As part of the landfill closure
activities, Madison County will construct an earthen/clay cap over the site. This ROD
addresses both the onsite and offsite contaminated ground water in an effort to minimize
the migration of contamination from the landfill to the surrounding community, to restore
the ground water to drinking water quality for the chemicals of concern, and to monitqr
ground water in a manner that will verify the effectiveness of the selected remedy. The
primary contaminants of concern affecting the soil and ground water are VOCs; other
organics; and metals.
The selected remedial action for this site includes installing a mUlti-layer clay cap
over the landfill; installing a storrnwater runoff system including dikes, impoundments,
and drainage ditches to control cap runoff; pumping and treatment of contaminated ground
water onsite using air stripping and carbon adsorption, reinjection of the treated ground
water offsite, or if infeasible, evaluating other disposal options including
infiltration, irrigation, or direct discharge; monitoring ground water; implementing
institutional controls including deed, land, and ground water use restrictions, and site
access restrictions including fencing; and providing a contingency for installation of a
passive gas and collection and control system, if methane is detected. The present worth
cost for this remedial action is $5,191,000, which includes an annual O&M cost ranging
from $109,000 to $409,000 for 25 years.
PERFORMANCE STANDARDS OR GOALS:
Chemical specific ground water clean-up goals are based on the federal and state MCLs.
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Record of Decision
The Decision Snmm.1'lry
Madison County Landfill Site
Madison, Madison County, Florida
u.S.
Prepared By:
Environmental Protection Agency
Region IV
Atlanta, Georgia-
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RECORD OF DECISION
DECLARATION
SITE NAME AND LOCATION
Madison County Landfill Site
Madison, Madison County, Florida
STATEHENT OF BASIS AND PURPOSE
This decision document presents the selected remedial action at
the Madison County Landfill Site in Madison, Madison County,
Florida, which was chosen in accordance with the Comprehensive
Environmental Response Compensation and Liability Act of 1980
(CERCLA), as amended by the Superfund Amendments Reauthorization
Act of 1986 (SARA), and, to the extent practicable, the National
Oil and Hazardous Substances Pollution Contingency Plan (NCP).
This decision is based on the administrative record file for this
site.
The State of Florida, as represented by the Department of
Environmental Regulation (FDER), has been the support agency
during the Remedial Investigation and Feasibility Study process
for the Madison County Landfill Site. In accordance with 40
C.F~R. S 300.430, FDER, as the support agency, has provided input
during this process. Based upon comments received from FDER, it
is expected that concurrence will be forthcoming; however, a
formal letter of concurrence has not yet been received.
ASSESSMENT OF THE SITE
Actual or threatened releases of hazardous substances from this
site, if not addressed by implementing the response action
selected in this Record of Decision (ROD), may present an
imminent and substantial endangerment to public health, welfare,
or the environment.
DESCRIP'.rION OF--'.rBE-REHBDY
This is the first and final cleanup action planned for the Site.
This action addresses the source of the soil and groundwater
contamination by containing the solid wastes and treating the
contaminated groundwater to acceptable levels.
The major components of the selected remedy include:
o
the implementation of institutional controls by state
and local government agencies, which would include deed
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-2-
restrictions, land use ordinances, physical barriers,
and water supply well permitting prohibitions (some
administrative difficulties may be encountered during
implementation of these various controls);
o
the construction of a groundwater extraction, treatment
(air stripping and Granular Activated Carbon - GAC),
and discharge (reinjection) system in the vicinity of
the Yard Trash Area (YTA), located at the southeast
corner of the landfill;
o
the installation of a clay/soil cap over the YTA only;
the contingent installation of a passive gas collection
and control system;
o
o
the construction of a stormwater management system;
o
the implementation of an extensive groundwater
monitoring program, which includes the installation of
two additional monitoring well clusters; and
long-term management controls including operation and
maintenance of the groundwater treatment system and the
Yard Trash Area cap.
o
The total present worth cost for the selected remedy as presented
in the Feasibility Study is $5,191,000. The actual cost will be
greater than this due to the installation of two additional
monitoring well clusters and other provisions added to the
selected remedy. Also, should additional sampling and
groundwater monitoring during remedial design and cleanup
identify other sources of groundwater contamination outside the
YTA, the selected remedial action will be modified to address
these areas and the costs adjusted accordingly.
STATU'l'ORY DETERMINATION
The selected remedy is protective of human health and the
environment, is cost effective, . and. it. complies~.with. Federal..and
State requirements that are legally applicable or relevant and
appropriate to the remedial action. This remedy utilizes
permanent solutions and alternative treatment (or resource
recovery) technologies to the maximum extent practicable and
satisfies the statutory preference for remedies that employ
treatment that reduces toxicity, mobility, or volume as a
principal element.
Because this remedy will result in hazardous source materials
remaining on-site ~ove health-based levels, a review will be
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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.
~~ 2.fJ /Pfz
. Date
~tY)~
fGreer C. Tidwell
Regional Administrator
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1.0
2.0
3.0
4.0
. 5.0
6.0
7.0
8.0
TABLE OF CONTEHTS
Site Name, Location and Description.....................l
Site History and Enforcement Activities.................4
Highlights of Community participation...................?
Scope and Role of Response Action.......................8
Summary of Site Characteristics.........................8
5 . 1 Geolo9Y'. . . . " . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
5.1.1 Site Stratigraphy, Structure and
Lineaments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
5.2
Hydrogeolo9Y'. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
5.2.1 Surficial Saturated Zone...................20
5 . 2 . 2 Conf ining Layer......................... . . . 26
5.2.3 Floridan Aquifer. . . . . . . . . . . . . . . . .'. . . . . . . . . .26
Groundwater Use................... . . . . . . . . . . . . . . . .27
Site Con tamina tioD. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
5.4.1 Groundwater Quality........................28.
5.4.2 Surface and Subsurface Soil Results........29
5.4.3 Pond Surface Water and Sed~ent Results....29,
5 . 4 . 4 Air Monitoring............................. 31
5.3
5.4
Summary of 8i te Risks................................... 31
6 . 1 Human Health Risks................................ 31
6.1.1 Contaminant Identification.................31
6. 1.2 Exposure Assessment. . . . . . . . . . . . . . . . . . . . . . . .33
6.1.3 Toxicity Assessment. . . . . '. . . . . . . . . . . . . . . .. .33
6.1.4 Risk Characterization Summary..............36
Environmental (Ecological) Risks..................38
6.2
Description of Remedial Action Alternatives.............39
7.1 Alternative 1 - No Action.........................39
7.2 Alternative 3 - Institutional Actions, Extraction
Wells, Air Stripping, Carbon Adsorption (GAC),
and Reinjection................................ .40
Alternative 6 - Institutional Actions, Cap Entire
Site, Extraction Wells, Air Stripping, Carbon
Adsorption (GAC), and Rein)ection.................46
Alternative 7 - Institutional Actions, Cap YTA
Only, Extraction Wells, Air Stripping',' Carbon- ..
Adsorption (GAC), and Reinjection...............53
Comparative Analysis of Remedial Action Alternatives....58
8.1 Threshold Criteria................................58
7.3
7.4
8.1.1
Overall P~otection of Human Health and the
. Environment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .58
8.2'
8.1.2 Compliance With Applicable or Relevant and
Appropriate Requirements (ARARs)...........60
Primary Balancing Criteria........................64
8.2.1 Long-term Effectiveness and. Permanence. . . ...64
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9.0
10.0
11.0
8.3
-2-
8.2.2
8.2.3
8.2.4
8.2.5
Reduction of Toxicity, Mobility, or
Vol11D1e ~.. ~ -. . . ~ ". . . . .0 . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Short-term Effectiveness...................64
Implementability.......................... .65
Co st. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 5
Modifying Criteria................................ 66
8.3. 1 State Acceptance........ . . . . . . . . . . . . . . . . . . .66
8.3.2 Community Acceptance.......................67
Selected RemedY............................8............. 67
Statutory Determinations.... . . . . . . . . . . . . . . . . . . . . . . . . . . . .74
10.1 Protection of Human Health and the
10.2
10.3
10.4
10.5
Environment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .75
Compliance with Applicable or Relevant and
Appropriate Requirements (ARARs) and To-Be-
Gonsidered Criteria (TBCs)........................75
Cost Effectiveness................................ 78
Utilization of Permanent Solutions and
Alternative Treatment Technologies (or " Resource
Recovery Technologies) to the Maximum Extent
Practicable. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .79
Preference for Treatment as a Principal
Element. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . . . . . . 79
Documentation of Significant Changes....................79
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ure 1. 1
Figure 1.2
Figure 1.3
Figure 5.1
Figure 5.2
Figure 5.3
Figure 5.4
Figure 5.5
Figure 5.6
Figure 5.7
Figure 5.8
Figure 5.9
Figure 5.10
Figure 5.11
Figure 5.12
Figure 5.13
Figure 7.1
Figure 7.2
Figure 7.3
Figure 7.4
LIST OF FIGURES
- Site
Vicini ty Map. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2
- Site
Map. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
- Location of City of Madison Public Wells.......5
- Generalized Stratigraphic Column...............10
- Location of
Soil Borings....................... 11
- Location of Monitoring and Private Wells.......12
- Geologic Cross-Section
- Geologic Cross-Section
A-A' . . . . . . . . . . . . . . . . . . . . 14
B-B' . . . . . . . . . . . . . . . . . . . .15
- Geologic Cross-Section
c-c' . . . . . . . . . . . . . . . . . . . . 16
- Isopach Map of Fat Clay of Hawthorne Group.....17,
- Geologic Cross-Section 'D-D' . . . . . . . . . . . . . . . . . . . .18
- Geologic Cross-Section E-E'....................19
- Northern Florida Geologic Structure............21
- Regional
Lineament Map......................... 22
- Surficial Saturated Interval Map...............23
- Surficial Saturated
Isopach Map................25
- Alternative
3 . . . '. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
- Alternative 3 - Institutional Controls.........43
- Alternative
6............. . . . . . .......... . . . .. .47
- Alternative
7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54
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Table 5.1
Table 5.2
Table 6.1
Table 6.2
Table 6.3
Table 6.4
Table 6.5
Table 6.6
Table 6.7
Table 6.8
Table 8.1
Table 8.2
Table 8.3
Table 9.1
Appendix A
LIST OF TABLES
- Contaminant Concentrations' and
Cleanup Goals....... ~ . . . . . . . . . . . . . . . . . . . . . . . . . . 30
- Draeger Tube Air Monitoring Results.~..........32
- Groundwater Exposure Point Concentrations......34
- Surface Soil Exposure Point ,Concentrations.....34
- Exposure Assumptions Used For Groundwater......35
- Exposure Assumptions Used For Surface Soil.....35
- Cancer Classifications and Slope Factors.......35
- Oral Reference Doses........................... 36
- Summary of Significant Carcinogenic Risks -
Future Residential Scenario....................37
- Summary of Significant Noncarcinogenic HOs -
Future Residential Scenario....................37
- Glossary of Evaluation Criteria................59
- Applicable or Relevant and Appropriate
Requirements (ARARs)........................... 61
- Groundwater Remedial AlternativeCost-"
Comparisons. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ~ . . .66
- Cost Estimate Remedial Alternative-7...........73
LIST OF APPBBDICES .,.
- Responsiveness Summary
.
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RECORD OF DECISION
SnmmAry of Remedial Alternative Selection
Madison County Landfill Site
Madison, Hadison County, Florida
1.0
Site Name. Location. and Descrintion
The Madison County Landfill Site (the Site) is located in Madison
County, Florida, in the eastern portion of the Florida Panhandle
(See Figure l.l). The City of Madison is the county seat,
centrally located within the county. The Site is approximately
two miles north-northeast of the City of Madison on county road
C-591. The landfill property occupies approximately 90 acres of
the National Priorities List (NPL)-listed Superfund site, which
is comprised of a total 133 acres owned by the county. Also.
located on the NPL-listed Superfund site directly south of the
landfill is the County Department of Transportation (DOT) and the
County's aviation hangar and landing strip (See Figure 1.2).
The landfill was operated as an unlined trench and fill
operation. Trenches (cells) of varying lengths and,widths,
typically 50 feet by 30 feet and approximately 15 to 25 feet in
depth, were used. Municipal/domestic and industrial wastes from
the area were placed in the trenches and covered with the
excavated material. Reportedly, there was no master plan
directing waste placement or trench orientation. Currently,
approximately 40 tons of waste per day are disposed into the one
group of remaining active waste cells at the Site. However,
Madison County is currently proceeding to perform a closure of
the active portion of the landfill in response to an order issued
to the county by the Florida Department of Environmental
Regulation (FDER). The closure includes the portion of the
landfill actively used for waste disposal after 1985 and will
consist of the construction of an earthen/clay cap. This closure
is expected to begin in 1993.
Figure 1.2 depicts areas of both active and'non-active (or
closed) trash cell locations. The Yard Trash Area (YTA), located
in the southeastern portion of the, landfill,. was primarily used
,to dispose of large bulk debris usually associated with
construction and demolition activities as well as drums
containing industrial wastes. The alleged Acid Disposal Area
located in the southern portion of the property was reportedly
used for disposal of acid wash water.
The surface of the landfill is covered with native soil that was
originally excavated from the trenches in preparing cells to
receive waste. Vegetative cover is absent over most of the
inactive or recently closed waste cells; however, over older,
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MADI~;ON, FLOI~IOA
Figure I. I
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HIGHWAY 591
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Figure
SITE MAP
MAD~ONCOUNTYLA~TIALL
Madison County Landfiil
Madison. Florida
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closed cells vegetative cover is present and consists of. shrubs,
grasses, and pine trees.
The City of Madison is supplied with potable drinking water from
four water wells located at three locations within the city (See
Figure 1.3), approximately 2.5 miles southwest of the Madison
County Landfill. The wells range from 8 inches to 14 inches
diameter, and are completed within the Floridan aquifer from 110
to 450 feet below the surface. The wells produce a total of 1.1
to 1.2 million gallons per day.
Due to relatively large hydraulic conductivities and
transmissivities in the Floridan aquifer, the city wells are
believed to induce a relatively small cone of depression in the
potentiometric surface of the aquifer. The average drawdown in
the four water wells is only 5 to 10 feet. Based on this
information, the four water wells are believed not to be .
influencing or extracting groundwater from the vicinity of the
Madison County Landfill.
The City of Madison's water system supplies water to all
customers located within the direct vicinity of the city.
Additionally, the city supplies water to selected residences
located near the landfill. The Locust Grove subdivision located
directly south of the landfill, all the residences on Route 4
located directly west of the landfill, and. the residences on SR-
145 from the intersection of Route-4 to C-254 are all supplied
with city water.
The population of Madison County is appro~imately 16,000, and the
population of the City of Madison is 3,700. Major industries in
the County include farming and timber (pulpwood). The area
surrounding the landfill is used as rural residential and
agricultural. Approximately 35 individual single family
residences are located within a 0.5 .mile radius of the landfill
property. Agricultural use in the area is quite varied. The
primary agricultural use is for tree farms and field crops. The
field crops consist of tobacco, soy beans, wheat, and corn. Some
of the other varied uses in the area include a vineyard,
livestock, waterfowl, and vegetable gardens. Livestock include
cattle, hogs, turkeys and chickens as well as water fowl such as
ducks and geese. Other animals raised in the areaninclude.
hunting dogs.. .
2.0
.. .. - .
Site Historv and Enforcement Activities
The Madison County Landfill began operation in 1970 as a sanitary
landfill operated by the City of Madison. From 1971 to March
1980, domestic waste from the City and surrounding area and local
industrial wastes were disposed of in the landfill. During that
time period, one local inqustry identified ..as having disposed of
waste in the landfill was ITT Thompson Industries, formerly a
division of ITT Corporation. Information compiled by the U.S.
Environmental Protection Agency (EPA) suggests that ITT Thompson
-4-
..
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MADISON COUNTY LANDFILL • *'..
SCALE
(feet)
Figure 1.3
LOCATION OF CTTY OF
MADISON PUBLIC WELLS
Location: Madison County Landfill
Madison, Florida
Source: USGS Ch«ny Lito »9T4> md Midiion f '.059'
POOR QUALITY
ORIGINAL
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delivered an undetermined quantity of liquid waste solvents,
semi-solid waste buffing compounds, and acid wash water' to the
landfill for disposal.
According to landfill operation personnel, 55-gallon drums
containing some quant~ty of liquid waste solvents were disposed
in a separate trash cell located in the YTA (See Figure 1.2).
Two drum removal operations were conducted by EPA in November
1984 and March 1985 in which approximately 20 drums, per removal
period, were recovered from the YTA. All drums in the YTA
containing volatile organic compounds such as DCE/TCE were
reportedly removed.
There is also information that ITT Thompson disposed of 55-gaI1o~
drums filled with waste polishing/buffer compounds at .the Site.
The polishing/buffer compounds are a semi-solid material used to
polish automobile ornaments. Based upon interviews with landfill
employees the exact location and number of drums in the landfill
could not be determined because disposal was sporadic over the
nine-year period. Landfill personnel stated that the drums
containing buffing compounds were emptied into the trash cells
with the domestic waste. The drums were then crushed and placed
into the trash cells.
From 1971 to 1974, ITT Thompson arranged for the disposal of acid
wash water, which reportedly was taken to the landfill. The acid
wash water may have contained chromic acid with maximum
concentrations of chromium of 50 parts per billion (ppb). No
information on the Ph of the acid wash water or the quantity
disposed was available. According to landfill personnel, the
contractor disposed of the acid wash water on the ground in the
area noted as the Acid Disposal Area (Figure 1.2). Conversations
with landfill personnel indicate that no other wastes were
disposed in that area.
The Suwannee River Water Management District (SRWMD) designed and
installed a groundwater monitoring network at the landfill in
1984. The results of the sampling events indicated the presence
of several volatile organic compounds in the groundwater at and
in close proximity to the landfill. This prompted FDER to take
protective action, and in 1986, the Florida Department of
Environmental Regulation (FDER) entered into a Consent Order with
the City, County, and" ITT" Thompson (the three identified
potentially responsible parties or PRPs) requiring them to
investigate groundwater near the Site. The PRPs identified the
affected private wells and provided those homes with bottled
water and ice, eventually connecting each home to City water
lines.
In early 1987, EPA scored the Site using the Hazard Ranking
System (HRS), a numerical system for evaluating a site's
potential risk to human health and the environment. The
aggregate HRS score derived for the Site was 37.93 based on the
level of groundwater contamination and was proposed for the
-6-
-------
National Priorities List (NFL). The Site was forma~ly added to-
the NFL on June-24, 1988. On June 11, 1990 EPA entered into a
Consent Order with the PRPs requiring the performance of a
Remedial Investigation/Feasibility Study (RI/FS). Implementation
of field activities as described in the RI/FS Work Plan began on
December 10, 1990 under EPA supervision.
During the RI/FS field work activities, soil, sediment, and
surface water samples were collected and 27 groundwater
monitoring wells were installed and sampled. Based on the
results of the initial phase of RI/FS field work, EPA recommended
additional field work to further assess the extent of soil and
groundwater contamination at the landfill. The additional field
work focused on the YTA and the installation of an additional
monitoring well, along with the collection of a second round of
groundwater samples. The final phase of RI/FS field work was
completed in late 1991, and the resulting RI and FS Reports were
submitted and approved by EPA in April and July 1992,
respectively. EPA released the Proposed Plan describing the
preferred remedial alternative to the public on August 24, 1992,
commencing the 30-day comment period. Comments received from the
public and the State have been incorporated into the
Responsiveness Summary, which is found in Appendix A of this
document.
3.0
Hiah1iqhts of Community Particioation
In accordance wit~CERCLA sections 113 (k)(2)(B)(i-v) and 117
requirements, a Community Relations Plan (CRP) for the Madison
County Landfill Site was developed. This Community Relations Plan
outlines citizen involvement and the community's concern.
Community concern regarding the Site peaked from 1984 to 1986,
when groundwater contamination was first detected in landfill
monitoring wells and residential wells. Concerned community
members included those having contaminated groundwater as a
result of landfill~erations. These affected individuals have
voiced their conce~ns at several County Commission meetings.
Citizens from Madison and surrounding communities have formed two
concerned citizen groups: the North Florida Drinking Water
Association and Save Our Counties (SaC).
During this 2-year-period of-peaked interest, a number of
newspaper articles regarding the Site were published.in local
papers. However, minimal community involvement has occurred with
regard to the Site since 1986. Currently, those concerned about
the Site are residents who must pay for City water since their
contaminated private wells are now nonpotable. Residents not
directly affected by the Site have expressed minimal concern
regarding the Site:.-.
EPA conducted an RI/FS kick-off meeting in Madison, Florida on
November 27, 1990 to inform the public of scheduled R1/FS
activities and of EPA's general involvement with the Site.
-]-
-------
Response from the community was very positive, most welcomed the
help of EPA with this matter. Additionally, in April 19'92 upon
receipt of the field sampling results, EPA released an RI Fact
Sheet describing the nature and extent of contamination at the
Site.
The RIfFS Reports and Proposed Plan along with all other
site-related documents were made available to the public on
August 24, 1992 in the information repository located in the
North Florida Junior College Library and at the EPA Records
Center in Region IV.
The public was provided an opportunity to comment on the remedial
alternatives for site remediation from August 24, 1992 to
September 23, 1992. In addition, a public meeting was held on
September 1, 1992 in Madison, Florida to present to the community
EPA's preferred alternative for source and groundwater
remediation at the Site. During the public meeting, the
community was informed of the availability of a Technical
Assistant Grant (TAG). A response to the comments received
during the public comment period is included in the
Responsiveness Summary, which can be found in Appendix A of this
Record of Decision.
This decision document presents the selected remedial action for
the Madison County Landfill Site, in Madison, Madison County,
Florida, chosen in accordance with CERCLA, as amended by SARA,
and, to the extent practicable, the National Contingency Plan
(NCP). The decision for this Site is based on the administrative
record.
4.0
Scone and Role of ResDOnse Action
This is the first and final planned remedial action for this
Site. The objectives for the remedy are to prevent the near-term
and future exposure of human receptors to contaminated -
groundwater both on and off-site, to minimize the migration of
contamination from the landfill to the surrounding community, to
restore the groundwater to drinking water quality for the
chemicals of concern, and to monitor groundwater in a manner that
'will verify the effectiveness of the selected remedy.
This ROD has been prepared to summarize the remedial alternative
selection process anq to present, the se~~cted, remedial
alternative for site remediation.
5.0
5.1
SnmmAT'V of Site Characteristics
Geology
This section describes site geological settings including the
stratigraphy, structure and lineaments.
-8-
-------
5.1.1
Site Stratigraphy, Structure and Lineaments.
The geology of Madison County involves differentiated formations
from the Tertiary to the present. The lowest geologic unit of
concern at this site is the white, "fossiliferous Suwannee
Limestone Formatio~ of the Oligocene Series (See Figure 5.1).
The lithologic description of sediment samples was recorded
during the installation of 15 soil borings and 28 monitoring
wells around the Madison County Landfill (Soil boring and
monitoring well locations are depicted in Figures 5.2 and 5.3).
The Suwannee Limestone was not encountered in two deep soil
borings (SB12 and SB3, see Figure 5.2). A series of sands,
silts, and clays were encountered in place of the limestone in
those two soil borings.
The relatively thin and discontinuous St. Marks Formation of
limestone forms the upper portion of the Floridan aquifer in
Madison County. Its thickness could not be determined at the
Site because samples could not be collected, due to a loss of
circulation of drilling fluids in this geologic unit.
The Miocene Hawthorn Group overlies the St. Marks and Suwannee
Limestone, forming the confining unit of the Floridan aquifer in
this area. The Hawthorn is extremely complicated and
heterogeneous, only the Torreya Formation of the Hawthorn Group
is present in Madison County.
In the study area, the Hawthorn Group is composed of two
lithologic units: (1) alternating layers of pure sands, clays,
and lenses of silty sandy limestone ranging in thickness from 5
to 50 feet, and (2) a bluish to greenish grey, highly plastic,
fat clay, which contains very little sand or silt, and has high
plasticity with a liquid limit greater than 50. The fat clay
unit was found in all subsurface borings except SB13 (See Figure
5.2). It ranges in thickness from 6 feet in SB5 to 60 feet in
SB8. The fat clay tends to conform to the topography of the
underlying Suwannee Limestone, making an effective seal, in most
places, against downward movement of contaminants into the
Floridan aquifer.
Sinkhole and other solution features have been formed throughout
the region during the geologic past, although the limestone
depression feature underlying the landfill may be due to recent
dissolution activities. A total of five geologic cross sections
were constructed across the landfill and the surrounding area to
help illustrate the geologic relationship between the overlying
sediments, the underlying Hawthorn Group, and the Suwannee
Limestone. The geological cross sections are based upon
lithologic well logs. In order to simplify the overall geology
under the landfill, relatively minor lithologic units generally
less than five feet i~ thickness were not incorporated into cross
sections.
-9-
-------
Geologic
System S.". 11m.
- eM. Y.)
HOIOC8M 0.01
o".,.",.r.,
----------- --------
Ptetl'OC8ft8 1.'
Eatlm Plnhandle FLORIDA
Geologic Formation Hydr08trltlgrlphic
Un.t
U"dltfar8ft'la,ecI
..
-
t.".ace marine and
fluvial d8p0ejta
(Und"'.entla'ld s.a".
and Clayl tNa r....,
Swftdal Iqultar ..,.,,,,,
-
--------------------------
Hawtflam aroult
Unclltf.8ftllatecl
,.
,,'
"
",
,
"
,,,,'
"
'"
IM"",eclla'. Iqulfar IV""" I
or I"t""'ldlatl conflnln; ...J
un" -------..
--'
-,-
----
Tlrtllry
PII0C8ft8
5.0
MIcca8uI&.. FonnaUon
MIOC8ft8
22.5
51. Marlt I Forma lion
Suwlllft.. U"'.81C1n8
I
I
FIOrtdIn lquttar ..,.tam 1
I
OIlIOC8M
37.5
. .
Eocene
5..0
OeaA8 OrOUll
-on P8ft Pam8t18n
OICllfMr UIM81C1n8
-
P.&8OC8M
11.0
C..., Key. UIM8toM'.
-------------------
ault-P IortcI8n
oontIlII"I IIfttt
..'"
"
,,-
,'"
,
,
,'"
,
"
,'"
..'
.
Cretaca-
IftCI Old.
1.,.0
.
UNIItfwantl8ted
.
Figure 5.1
GENERALIZED
STRATIGRAPHIC COLt,yl~
Source: Florida Geol.ogieSurvey, Bull. No. 61
. (Hoenstine, Sptncer, and O'Cmall, 1990)
Location: Madison County Landfill
Madison, Florida
-10-
-------
C -591
Depanment
Of
TI3nSpCI'Wion
Acid
Disposal
Area
SCALE
~
o 2.50 500 1000
~
8M. Bench Mark USC&GS (143.6' MSL)
. . Soil Bonng Location
--- Property Boundary
- Paved Road
- Dirt Road
"}::q Cosed Trash Cells
. Private Water W~Us
.' .
SR-l~5
~ .-. h__-- .. -
S17
SB8
SBl
SB6
.
SB
.
t
1
Figure 5..2
LOCA 110NS OF SOn.
BORINGS
Location: Madison County Landfill
Madison, Aorida
-11-
-------
C-591
SR-145
Transponauon
Aod
Disposal
0 250500 1000
EXPLANATION
BM- Bench Mark USCStGS (143.6'MSL)
• n Monitoring Well Location
• Existing Monitoring Well Location
—— Property Boundary
— paved
""""""" Din Road
SHI Closed Trash Cells
* PnvateWaierWeUs
S - Shallow well I - Intennediaie well; D-DeepweU
No«: Private Well Owners are listed in TaWe 1-1"
Figure 5.3
. LOCATIONS OF
MONITORING
AND PRIVATE WELLS
Location: Madison County Landfill
Madison, Florida
-------
One east-west a~d two north-south cross sections were constructed
across the landfill (Figures 5.4, 5.5, and 5.6). Figure 5.7
illustrates that the fat clay unit can be correlated across the
entire landfill and the fat-clay-uni~ increases in thickness in
the center to the western portion of the landfill. The Suwannee
Limestone, however, was not detected as underlying either the
western (SB12) or eastern (SB3) portion of the landfill.
Limestone was encountered in the central portion of the landfill
at a depth of 190 feet. Approximately 300 feet west of soil
boring SB12, at soil boring SB15, limestone was encountered at
the depth of 85 feet below land surface.
The cross section in Figure 5.5 parallels the western perimeter
of the landfill. This cross section illustrates that the fat
clay unit was not detected in soil boring SB13. The primary
lithologic type in SB13 was a silty, sandy clay. Figure 5.4 a160
illustrates the undulatory nature of the Suwannee Limestone under
the landfill.
Figure 5.6 parallels the eastern perimeter of the landfill. The
fat clay unit was found to be present across this portion of the
landfill property. The fat clay unit thins in the vicinity of
IT1/SB1. Limestone was encountered relatively close to the
surface at approximately 40 feet Mean Sea Level (MSL) at soil
borings SB4 and SBl. All three cross sections illustrate that
below a portion of the landfill the Suwannee Limestone was not
encountered to a depth of 200 feet below the surface. In areas
in which limestone was relatively deep or not found, the
overlying distinguishable units were continuous.
Two cross sections were also constructed from lithologic data
obtained during well installations in the vicinity surrounding
the landfill. One cross section was constructed in a northwest-
southeast (Figure 5.8) and another northeast-southwest trend
(Figure 5.9). Both cross sections illustrate -that sediments
outside the landfill area are more homogenous. The fat clay
overlying the Suwannee Limestone was encountered in all
monitoring wells off-site.
The absence of a fat clay in the vicinity of soil boring SB13 and
the clay's thinness in the vicinity of test boring SB5 and
monitoring well IT1 indicate there is a potential, unless blocked
by the vertically upward hydraulic gradient, for surface water to
infiltrate through the overlying sediments and percolate into-the
Floridan aquifer in these areas. Additionally, the Suwannee
Limestone is higher in elevation and near the ground surface at
test boring SB5 and monitoring well IT1.
Figure 5.7 illustrates that the fat clay unit was either missing
or relatively thin in the south/southwestern and northeastern
areas of the landfill. Thick fat clay deposits correlate with
topographically higher surface elevations, and relatively thin
clay deposits coincide with lower elevations.
-13-
-------
QOSJ Section
^Mgmj^^pgsa^BM^^i^^f: '$ftv..
... IVJWsOHKHSjj&jj&^j'Sis ^ksVvSfsSfcVt; jv'jvV •
•••»> i-ii i i i ,,m, i, f V.....1<-.!„ gj b j...
r*~»^l/C%vvVvvJ%vv>Ky
VVrTr^V>V*SV%%%%XfinfS
*^^ ^ t*. i-^m. * r- r. r. «i *t 4^ n »--^T^ .jKL^t i**^'
Vcracal EuggcnHM -10.0
EXPLANATION
Quanz Sand
Silty Sand
Silt
Sandy Silly Clay
Fat Clay
Organic Silly Clay
Silty Limestone
Figure 5.4
OEOI.OOIC CROSS
SECTION A A'
.ocalion:
Madison County Landfill
Madison. Honda
I
-------
%y*yvVyvyv>A%vv>
.WVvWV.'.-T -V-
Vertical Eiciggeratian - 10 0
Quart/ Sand
Silly Sand
Sill
Sandy Silly Clay
Fai Clay
Organic Silly Clay
Silly Limestone
GF.OI.OO
SUCTION B B
-------
Sy??r?w?»T*^'+vvvv+%%vv%vv'
»>»»»!WvVvW%VvMaMJh***
•^ssHS&iB&S&reS&S
m%^M®88&®®i
««jf»wv
Vertical K»aggcraiitm - 100
EXPLANATION
r~~] Quartz Sand
Silly Sand
Sill
>1 Sandy Silly Clay
r-al Clay
Organic Silly Clay
Silly Limeslonc
2Ha»wPir.*r* + * v * vn^ »3fc*T*T-r*T*i
Figure 1.6
F.oi.(x;irnMi
si-tmoN c tr
-------
WEW a.AY
SOIL 11tI:INESS
(f8c)
t!I:.l T
5B.Z ZO
,.J T
loA 6
.,
.
. 1
61
58.9 29
58.1 H
58.\ 38
58.\ 38
58.1 0
58.\ Z3
8.1 J2
..& 24
., \
:-6 Jj
.7 \1
IT., 20
rr-9 29
IT-\O 24
!fT .11 33
fT -I:l 26
fT .;3 :9
)
SCALE
~
o 250 m 1000
~
8MI' Bench Mark USC&GS (143.6' MSL)
. IT MonitOring Wells .
. Existing MonitOring Wells
6 Soil Borings
. - - - Propeny Boundary
- Paved Road .
- Din Road
- 1 0' Isopach Contour of Fat Clay
.
.
IT12
'\J
:)
\
;;11
ef\
'-
\
i
IT9
~
\
Figure 5.7
[SOPACH MAP OF
fAT<1AYOF
HA WIHORN GROl"P
t
I
Location: Madison County Landfill
Madison, Aorida
. -17-
-------
cx>
I
C/J
3E
I
y,
_j
u
150 -
140 -
130 -
120 -
110 -
100 -.
90 -
-80 -
- 70 -
- 60 -
- 50 -'
- 40 -
- 30 -
- 20 -
- 10 -
-0 —
- 10 -
- -20 .
HORIZONTAL
SCAU-:
(feel)
II IINI KKI 5(N)
Vinii.il l.
("niss Srtlion
I xxaiHMi Map
LXPLANATiUN
l Quart/ Sand
Silly Sand
Sill
Saiuly Silly Clay
l:aiOay
3 Silly I mieslone
K i gure S . 8
alum
si;cnoN i
Mailisou ( iMiniy
Mailison, l-'lurula
-------
. vy....-..•.-•...--.• ...y^J j« ( ^^-p^^
%r»?ft»>»^%v^%vvvw^v*%%v»vv%v..'v%
^J>^%VV\Vv%VWVVV%%%V*VVVk^K%VvVr't-rk
^>>>>VVVV%V»Vt.VWvVk.VWV^aliB^tt.fcii
>>>>>^>vvvwK£TKvfcC5&Zafiiii^MBEIS>*
V.IWVWV4VVVVlVv.».VV%
^>>>>>vv%Tvvt%vK:
EXPLANATION
] QuaitzSand
| Silty Sand
| Silt
] Sandy Silty Clay
j] Fat Clay
| Silty Limestone
Crois Stcnon Loobon M«p
I^ORIZO^fTAL
SCALE
(Feet)
0 100 300 MX)
Veracal ExAggcniian = 20 0
l.ocaliun:
Figure S.9
OEOKKilClUOSS
SECTION E f:
Madison County Landlil
Mailison. Honda
-------
The Hawthorn Group is unconformably overlain by the Pliocene -
Miccosukee Formation, consisting of very fine to course,' poorly
to moderately sorted, reddish-orange sands to grey sandy clays.
The Hawthorn-Miccosukee contact is usually indistinguishable
because of the similarity and heterogeneous nature of both
formations. At the Site, the Miccosukee is found in the
topographic highs, generally above 130 feet MSL, and averages
about 20 feet thick.
The entire area is overlain by one to ten feet of Pleistocene and
Holocene Undifferentiated Sands and Clays, which are particularly
prevalent (about 10 feet thick) in low lying areas where surface
runoff collects.
Madison County, Florida, is located on the north flank of the
Ocala Platform (Figure 5.10). The Apalachicola Embayment tends
northeast-southwest just to the northwest of Madison County.
Regional linear structures, including lakes, ponds, and marsh
areas, are oriented or elongated either northeast-southwest, or
northwest-southeast. The elongated lakes are formed by surface
water collecting within topographic depressions, formed by
dissolution of the underlying limestone bedrock. Dissolution of
the limestone occurs at a relatively faster rate in fractured
areas because of the increased porosity, and resulting increased
groundwater flow, in these areas.
Lineaments may be the surface expression of fractures in the
underlying Suwannee Limestone. The lack of subsurface control
and surface exposures makes it difficult to determine whether or
not all the map lineations represent fractures. The lineament
study of available photographs reveal several lineaments near the
Site (See Figure 5.11). Lineaments are visible in the central
and western portions of the county west of the. Site; however,
lineaments tend to end abruptly just east of State Route (SR)
145. Although the exact lineaments paths may vary slightly, a
lineament (linear structure) trends east-southeast through the
Yard Trash Area (YTA) (See Figure 5.11).
5.2
Hydrogeology
The two hydrogeologic units present at the Site, the surficial
saturated zone and the underlying Floridan aquifer., are
investigated and their-characteristics. are discussed below.
5.2.1
Surficial Saturated Zone
One of the goals of the RIfFS was to assess the presence of a
laterally continuous, permeable saturated zone that has the
capability of transporting contaminants away from the landfill.
Figure 5.12 illustrates the delineation of.the three saturated
horizons or zones in the subsurface, one within the landfill area
from 70 to 90 feet above Mean Sea Level (MSL), the other larger
zone outside the landfill area from 85 to 95 feet above MSL, and
-20-
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APALACHlCOLA
EtJBA ytJENT
-r------ "\
, ---- ,
( ~-
o 30 10 ml
I . I' I I ,
o 20 .0 eo 80 100 km
()
I
?
.~
..a~ ."
'.
.
Figure 5.10
NOR1HERN FLORIDA
GEOLOGICSTRUCTCRE
M~ed From: Rorida G~Jo8ic Survey, Bull. No. 61
(Hoenstine. Spencer. and Q'CaIroll. 1990)
Location: Madison County Landfill
Madison. Aorida
-21-
-------
C-591
SR-'45
US-90
SCALE
(Feet) .
o IlIID :IOOD
- -
- -
'000
. .
t
N
i . Location:
Figure 5.11
REGIONAL LINEA.."1E~ 1
MAP
[J
Madison Co~ty Landfill
Madison. Aorida
-22-
-------
C.S91
~
, (
I
I
.~B2.
I
I
SR.14S
~6
SB . fZ ~
~B14
.
IT 12
IT! 1
.
.
. J1.;;j
. I'
I
I :' '.
I
Ail I ';
Scrip' ',.'
I
I
~8
SCALE
(feet)
~
o 250 SOO
,
1000
~,
8M- Bench Mark USC&GS (143:6' MS~
. IT MonitOring Wells
. Existing Monircring Wells
A Soil Borings .,.
- - - Property Boundary
- Paved Road
- Din Road
CZD SatUrated Zone Elevation < 70' MSL
c::::> SatUrated Zone Elevation 70' - 90' MSL
~ SatUrated Zone Elevation> 85'-95' MSL
.. ...:,
t
N
j
Figure 5.12
SURRCAL SA TURA TED
INIERV AL MAP
Location: Madison County Landfill
Madison, Florida
-23-
-------
1-
the third, and smallest zone between the other two, on top of the
clay unit from 36 to 41 feet above MSL, occupying the area around
IT3/SB6.
Landfill Surficial Saturated Zoner- Figure 5.13 depicts the
thickness of this saturated zone within the landfill. The map
shows the thickest portion of the saturated zone being located
beneath the trench/pond in the center of the landfill. No
saturation was present along the boundary of the southern and
southeastern corner of the landfill. Therefore, the edge of the
saturated zone if determined to be in its permanent location
.would.be a barrier to transport of contaminants in a lateral
direction. However, the possibility of contaminant migration in
the natural gas stream does exist at the landfill.
The saturated layer within the landfill has a very consistent
bottom horizon of approximately 71 feet MSL. The trash cells in
the landfill exist to a depth of approximately 25 feet below the
surface which is approximately 75 above MSL. This saturated zone
within the landfill appears to be associated with the old trash
cells contained within the landfill, which are less dense and
more permeable than the underlying and surrounding geologic
material. Hence, water percolating downward encounters the fat
clay unit underlying the landfill and is prevented from further
migration. This discussion also explains why this saturated zone
is limited to the area of the landfill.
The surface water pond located on site is believed to be
hydrologically connected to the saturated zone within the
landfill. Based upon direct observations made during significant
precipitation events, the pond/trench was observed receiving
substantial volumes of precipitation via surface water runoff.
The pond is believed to be a source or area in which surface
water has a means of entering into the shallow saturated zone
underlying the landfill; however, contaminants were not found in
the pond sediments. Only as the pond dries by evaporation would
contaminants be carried from the landfill to the pond area, and
they would be flushed back into the landfill again during the
next rain.
Surficial Saturated Zones Outside the Landfill: These two zones,
both to the southeast of the-landfill, are at ,different.
elevations from that within the ~andfill; and no hydraulic
connections are indicated. The elevations of the large saturated
zone to the southeast overlap somewhat, but are higher than, the
elevations of the saturated zone within the landfill. If there
were a hydraulic connection, flow would be toward, rather than
away from, the landfill. Therefore, contamination would still be
contained within the landfill.
In the vertical direction near the surface, downward contaminant
transport is relatively higher than horizontal transport, because
surface water streams do not exist in the area. Therefore,
precipitation that inf~ltrates into the ground moves primarily in
-24-
-------
SURFICIAL
SA 1URA1ED
SOIL THlCHNESS
BORING (Feel} .
5B-l 0-
5B-2 0
s-3
-4 (
- (
- 1
1B .l 2
<;:B.l1 4
C;:U-
-
- .
-I~ l.
~IT2ISB2
o
10
SCALE
(Feet)
~
o 100 200 ~oo 500
I
i
i '
~rr1/SB 1
..-..-..-..-..-..-..-..-..':J
5
C-591
~
~ IT Moniroring Wells
. Existing Moniroring Wells
. "SoilBorinp
-..- Pro~ Boundary ,
- Paved Road
- Dirt Road
- Cased Trash Cells
- Active Disposal Area
-, - SaIW'ared Zone Thickness (Feet)
I
I
I
I
I
i. .
;" DqI.'"-ot
;" ex
/ .~I8IIIpYo~
:/ ),
..' A. ,,'.'
.' I.
.' Ri'
; ....
IS.'.'"
I Tn)'.
I It../,
I 1./
I P
.
Acid
Disposal
Area
.f
N
I
Figure 5.13
SURFICIAL SA TURA TE
ISOPACH MAP
.
~
i
i
I
I
.'
.' . " !
. .
Location:
Madison County Landfill
Madison Florida'
-25-
-------
a vertical direction, and contamination of the Floridan aquifer,
unless blocked by the upward vertical gradient from the 'Floridan
to the surficial aquifer, could be the result of waste disposal
in the surficial sed~ents.
5.2.2
Confining Layer
The confining layer that hydrologically separates the surficial
saturated units from the Floridan aquifer is the Hawthorn Group
of sed~ents (Described in Section 5.1.1). Specifically, both
the sandy silty clay unit and the fat clay unit of the Hawthorn
Group together make up the confining layer of the area. Both
units varied lithologically and in thickness throughout the study
area.
During the installation of IT14S, a shelby tube soil sample was
collected from the center of the silty clay unit for permeability
testing. The vertical hydraulic conductivity of the silty clay
is 2.9 X 10-8 cm/sec. This value defines the silty clay unit as
an aquiclude. By definition, an aquiclude is capable of storing
groundwater but can only transmit it very slowly. The fat clay
unit is considered to be a confining unit because its silt and
sand free nature is believed to result in a vertical conductivity
lower than the sandy silty clay unit. Subsurface data indicates
that a confining unit of variable thickness exists under the
landfill.
5.2.3
Floridan Aquifer
The Floridan aquifer is the pr~ary hydrogeological unit of the
study area. It is sealed, except possibly in local areas of
collapse into solution cavities, by the Hawthorne Group of
sed~ents, particularly by the fat clay unit. Most of the
groundwater flow in the Floridan takes place in the upper 200 to
300 feet, which is characterized by numerous cavities and a high
degree of secondary porosity, and is in a southeasterly
direction.
Slug tests were performed at five well clusters for a total of 15
wells in order to assess the hydraulic characteristics of the
Floridan aquifer at the selected well locations. Shallow,
intermediate, and deep monitoring wells were tested,to help
assess the vertical-flow component of the Floridan aquifer.
The average transmissivities at the shallow~- intermediate, and
deep wells (all penetrating into the Floridan aquifer) in the
study area were 159, 549, and 496 square feet per day (ft2/d),
respectively. The range of hydraulic conductivities and
transmissivities computed for the Site is in the range of values
established for karst l~estone. The results indicate that the
transmissivities and hydraulic conductivities increase with depth
within the top 200 to 300 feet of the Floridan aquifer. The
uppermost por~ion of the aquifer, having the lower
transmissivity, is composed of fine grained sed~ent infilling
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irregular solution cavities; whereas, the deeper portions of the
Suwannee Limestone have larger solution cavities and less fine
grained sediment within these cavities.
The measurement of localized hydraulic gradients and subsequent
flow velocities may not yield an accurate picture of the Floridan
aquifer flow characteristics because of the heterogeneous nature
of the subsurface. During the installation of wells at the Site,
numerous cavities of varying size were encountered in the
limestone aquifer. Figure 5.11 identifies the potential presence
of a lineament in the subsurface trending through the YTA from
the northwest to .the southeast. Such 'lineaments are
manifestations of the subsurface geological structure, which may
be composed of many fractures, cavities, or rubble zones. A
lineament suggests the existence of a preferred pathway for
groundwater flow in the subsurface.
Given the many uncertainties in the heterogeneity of the aquifer
material, only an estimate of the actual groundwater flow
velocities in the Floridan aquifer can be made.
Horizontal Flow: Horizontal flow velocities were calculated
using two separate methods. Under the first method, Darcy's Law
(v = K I) was used to calculate a bulk velocity under the
assumptions of a homogeneous and isotropic medium, and the
resulting horizontal flow velocity was 14.7 feet per year (ft/yr)
in a northwest to southeast direction.
A second method was based on the elapsed time from disposal of
trichloroethene (TCE)/dichloroethene (DCE) in the Yard Trash Area
to first appearance in the nearest point of detection in
downgradient domestic wells, and the assumption that these two
events were correlated. This resulted in a travel time from 1971
to 1984 over a distance of 2000 feet from northwest to southeast,
or approximately 140 ft/yr. An order of magnitude increase over
the Darcy's Law calculation implies the potential presence of a
preferred pathway in the subsurface.
Vertical Flow: Water level measurements recorded in the
monitoring wells comprising the well network indicate the
presence of a vertical hydraulic gradient in the Floridan
aquifer. An average upward flow gradient of 0.00326 ft/ft was
obtained from well clusters screened in four zones within the
Floridan aquifer. This indicates the potential- for' a vertical,
upward groundwater flow that would tend to keep any contamination
within the upper zones of the aquifer.
5.3 Groundwater Use
The Madison water supply is obtained from four wells located at
three locations within the city (See Figure 1.3). These wells
are approximately 2.5 miles southwest of the Madison County
Landfill and are completed within the Floridan aquifer from 110
to 450 feet below the surface. Because of the large
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transmissivity of the Floridan, the average drawdown in the four
wells is only 5 to 10 feet. Also groundwater flow in the region
is from north west to south east. Based on this information,
these wells are believed not to be influencing or extracting
groundwater from the vicinity of the Madison County Landfill.
The Madison water supply furnishes potable water to all customers
within the city and to selected residences near the landfill.
These residents include the Locust Grove subdivision, located
directly south of the landfill~ all residences on Route 4 located
directly west of the landfill~ and the residences on SR-145 from
the intersection of Route-4 to C-254. A well survey was
performed for the private water wells located within
approximately one mile downgradient of the landfill. It was
determined that approximately sixty property owners within this
one mile radius are using their private water wells for
irrigation, and possibly other purposes.
5.4
Site ContAmination
Sampling was performed in those areas with the highest potential
for contamination, which included soils and groundwater on-site
and at the perimeter of the landfill. Sampling was also
conducted in areas which would not have been impacted by the
landfill to establish background parameters near the Site.
A total of three background soil, four trench, twenty-two surface
soil, sixteen subsurface soil, two pond sediment, and two pond
surface water sam~es were collected during the RI. In addition,
a total of twenty-eight groundwater monitoring wells were
installed at depths\'from fifty-six to one hundred and forty-six
feet for the colleqtion of groundwater samples. Several existing
monitoring and private wells were sampled as p~rt ~f the RI.
5.4.1
Groundwater Quality
Twenty-eight groundwater monitoring wells were installed at the
Site in both the s~ficial saturated zone and the Floridan
aquifer to determine the extent of groundwater contamination
(Figure 5.3 illustrates well locations). Twenty-seven
groundwater monitoring wells were installed during the first
phase of RI field work. The final monitoring well was installed
after additional data needs were identified by EPA.,
Monitoring wells were completed at varying depths into the
Floridan Aquifer to obtain discrete vertical groundwater data.
The definition for shallow, intermediate, and deep monitoring
wells is as follows:
o
Shallow - ~p.. approximately 10 feet below top of rock
Intermediate - To approximately 25 feet below top of rock
o
o
Deep - To approximately 50 feet below top of rock
.'
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Groundwater contamination in the study area primari~y involves'
low concentrations of halogenated volatile organic compounds
(VOCs) in the Floridan aquifer at the Yard Trash Area, in the
southeast corner of the landfill (Wells HI and ITl).
The two contaminants detected in the groundwater at the greatest
concentrations were TCE and cis-l,2-DCE. Other halogenated VOCs
detected include chloromethane, vinyl chloride, 1,1-
dichloroethene, 1,I-dichloroethane, 1,1,2-trichloroethane,
trichlorofluoromethane, dichlorodifluoromethane, cis-l,2-DCE,
chloroform and acetone. All of these VOCs have the potential to
migrate in the groundwater. As stated in the RI Report, these
contaminants have not been detected in downgradient monitoring' '
wells with the exception of TCE and cis-l,2-DCE at IT4D and
chloromethane at ITll.
Table 5.1 lists a comparison of measured on-site concentrations
of the identified chemicals of concern for groundwater with their
respective maximum contaminant levels (HCLs), set according to
the Safe Drinking Water Act and Florida's Drinking Water
Standards.
Although inorganic constituents (i.e. metals) and pesticides/PCBs
are present, detected concentrations were either comparable to
background and health-based acceptable levels or were detected in
only a single monitoring event, and therefore neither chemical
tyPe poses a threat to groundwater quality in the vicinity of the
landfill. Groundwater sampling results indicate that the
Floridan aquifer has been impacted by conditions at the Madison
County Landfill; the contamination has migrated a short distance
beyond Site boundaries, somewhat less than 1000 feet downgradient
of the YTA.
5.4.2
Surface and Subsurface Soil Results
Surface and subsurface soil samples collected during the RI
indicate soil contamination is present primarily within the YTA
to depths less than three feet. The main contaminants detected
in the YTA soil include methylene chloride, acetone, toluene, 1,1
DCE, and 1,2 DCA. Low concentrations of several semi-volatile
organic compounds, and pesticides were also detected in the YTA.
All detected organic chemicals, with the exception of those
listed on p.6-26 of the FS Report (frequency of detection was
much less than 10%), are of concern because background
concentrations of these chemicals in soil is assumed to be zero.
However, most concentrations of these chemicals are low. The
only inorganic constituents of concern detected in the YTA soils
are barium, beryllium, and cobalt.
5.4.3
Pond Surface Water and Sediment Results
Two pond surface water and two pond sediment samples were,
collected du~ing the RI. No organic chemicals were detected
above the detection limit in either sediment or 'surface water
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TABLE 5.1
CONTAHIHANT CONCENTRATIONS AND CLEANUP GOALS
Chemicals in Groundwater an-Site (ug/l) HCL (ug/l)
l,l-dichloroethane 70 2,400.0**
l,l-dichloroethene 65 7.0*
cis ~,2-dichloroethene 1,400 70.0*
Trichloroethene 2,800 3.0**
Tetrachloroethene 120 3.0**
Vinyl chloride 42 1. 0**
l,l,l-trichloroethane 20 200.0*
1,1,2-trichloroethane 5 5.0*
Bis(2-ethylhexyl)phthalate 5 4.0*
Dichlorodifluoromethane 12 1,400.0**
Trichlorofluoromethane 19 2,400.0**
---
Rote: Federal MCL - *
State MCL - **
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samples. There~ore, there are no organic chemicals of concern in
these media. None of the inorganic concentrations found in the
pond sediments were above background concentrations, which were
developed from regional data andsite~specific sampling, with the
exception of barium. No inorganic chemicals were above
background concentr-ations in the surface water. Therefore, the
only chemical of concern in either of these media is barium in
the sediment.
5.4.4
Air JIoni.toring
Air monitoring data obtained during both phases of RI field work
indicated that airborne volatile organic compounds (both
particulate and vapor phase) were not problematic at this Site.
Prior to excavation, drilling, and sampling activities, on-site
workers tested the air quality with either Draeger Tubes, a flame
ionization detector (FID), and/or an organic vapor analyzer
(OVA). Instrument readings were taken continuously at each
drilling location ITl through ITa, and at the trench excavation
operation. Table 5.2 presents the results of the Draeger Tube
sampling. In addition, VOCs were not detected during air
monitoring conducted in support of the RI Health and Safety
program. Evaluation of these data supported by historical
information leads to the conclusion that airborne contaminant
transport is not a significant migration pathway at the Madison
County Landfill Site.
6.0
6.1
Snmm;:!lTV of Site Risks
Human Health Risks
The baseline risk assessment provides the basis for taking action
and indicates the exposure pathways that need to be addressed by
the remedial action. It serves as the baseline indicating what
risks could exist if no action were taken at. the Site. This
section of the ROD summarizes the results of the baseline risk
assessment conducted for this Site. The components of the risk
assessment include contaminant identification, exposure
assessment, toxicity assessment, and a risk characterization.
6.1.1
ContAminAnt Identification
At the Madison County Landfill Site the following media were
assessed for contamination: groundwater, surface soil, surface
water (intermittent pond), and sediment (pond).
For each contaminant of concern in a given medium, an exposure
point concentration was determined by calculating the statistical
upper confidence limit (UCL) of the sample results. If too few
data were available to calculate a UCL, the maximum detected
value was used as the. exposure point concentration. Exposure
point concentrations are shown for all contaminants of conce~ in
groundwater and surface soil in Tables 6.1 and 6.2. Levels of
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Table 5.2
Dr..gtr Tub. Air Monitoring R..ult.
Madison County landfill
Madison, F10rida
LOC.AT1ON SMFlE NO. CDFCXH) AEACING (ppm)
Ts.3 1 M81'cury 0
2 ~ c:tIloricH 0
3 a"omic AcicI 0
4 Trlc:tl1oroettIyIene 0
! Vinyl QlIorid8 0
. e Benzene 0
S~1 1 T rlc:tl1orodI~"", 0
2 Methylene Qllonde 0
3 M81'cury 0
4 Qlromic AcicI ~ \
! Benzene - 0
e Vinyl Qlloride 0 I
7 Trlc:tllor08ttIyI8'" 0
. M8thy4ene QlIortde 0
NOTE:
No \/0181118 organics were d8t8Ct8d usinG an O';anic V8f# An8tyz8r .
..
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cnem~ca~s ~n ~he pond (water and sediment) were det~rmined to be
insignificant in regard to potential human exposure.
6.1.2
Exposure Assessment
Currently the Sit~ is a municipal landfill, surrounded by rural
residential and agricultural land. For the current scenario, it
was assumed that a child trespasses the Site on a regular basis.
Since some of the nearby private wells have shown contamination
(necessitating the providing of municipal water to these
residents), exposure to the groundwater at the perimeter of the
Site was determined to be a current pathway as well. Because of
the land use of the surrounding area, it is possible that in the
future the Site could become residential/agricultural if deed
restrictions are not enacted and enforced at the time of the
landfill closure. Therefore, the baseline risk assessment
assumed that residents would live in the most contaminated area
of the Site in the future use scenario. Assumptions included
exposure to site groundwater and surface soil by the future
hypothetical resident. The future scenario also included
residential consumption of beef, vegetables and fruit grown on
the Site, as well as consumption of milk produced from beef grown
on the Site, but these pathways did not result in significant
risks. The exposure assumptions used for groundwater and surface
soil are shown in Tables 6.3 and 6.4.
6.1.3
Toxicity Assessment
Under current EPA guidelines, the likelihood of adverse effects
to occur in humans from carcinogens and noncarcinogens are
considered separately. These are discussed below.
Carcinoaens: EPA uses a weight-of-evidence system to classify a
chemical's potential to cause cancer in humans. All evaluated
chemicals fall into one of the following categories: Class A -
Known Human Carcinogen; Class B - Probable Human Carcinogen (B1
means there is limited human epidemiological evidence, and B2
means there is sufficient evidence in animals and inadequate or
no evidence in humans); Class C - Possible Human Carcinogen;
Class D - Not classifiable as to Human Carcinogenicity; and Class
E - Evidence of noncarcinogenicity for Humans.
Cancer Slope Factors (SFs), indicative of carcinogenic potency,
are developed by EPA's Carcinogenic- Assessment Group to estimate
excess lifetime cancer risks associated with exposure to
potentially carcinogenic chemicals. SFs 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. SFs, which are expressed in units of
(mg/kg-day)-l, are multiplied by the estimated intake of a
potential carcinogen to provide an upper-bound estimate of the
excess lifetime cancer risk associated with exposure at that
intake level. The term "upper-bound" refers to the conservative
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1-
Contaminant of Concern Concentration- CUrrent Concentration- Future
Land Use Land Use
Chloroform 0.001 N/A
Trichloroethylene 0.002 2.8
Chloromethane 0.005 N/A
1,2-Dichloroethylene 0.002 1.4
Bis(2-ethylhexyl) N/A 0.005
phthalate
Carbon Disulfide N/A 0.052
Dichlorodifluoromethane N/A 0.021
1,1-Dichloroethane N/A 0.07
1,1-Dichloroethylene N/A 0.065
Tetrachloroethylene N/A 0.12
1, 1, 1-Trichloroethane N/A 0.02
1,1,2-Trichloroethane N/A 0.005
Trichlorofluoromethane N/A 0.019
Vinyl chloride N/A 0.042
Rote: N/A - Th1.s chem1.cal not of concern for the current land use scenar1.o.
TABLE 6. 1
GROUNDWATER EXPOSURE POINT CONCENTRATIONS (mg/L)
TABLE 6.2
SURFACE SOIL EXPOSURE POINT CONCENTRATIONS (mg kg)
Contaminant of Concern Concentration- CUrrent & Future Land
Use
Barium 599.0
Acetone 0.042
1,2-Dich1oroethane 0.011
1, 1, 2, 2-Tetrachloroethane 0.001
Benzoic Acid -
0.3
Bis(2-ethylhexyl)phthalate 1.4-. ,- - - ._n..
Di-N-octylphthalate 0.23
alpha-chlordane 0.008
beta-BRC 0.034
DDT 0.042
gamma-chlordane 0.016
I
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TABLE 6.3
EXPOSURE ASSUHPTIONS USED FOR GROUNDWATER
Parameter Value used for Resident Adult
Ingestion Rate (I/dy) 2
Exposure Frequency (dy/yr) 365
Exposure Duration (yr) 30
Body Weight (kg) 70
TABLE 6.4
EXPOSURE ASSUHPTIONS USED FOR SURFACE SOIL
Parameter Value used for Value used for Value used for
Child Child Resident Resident Adult
Trespasser
Ingestion Rate (mg/dy) 100 200 100
Exposure Frequency 156 365 365
(dy/yr)
Exposure Duration (yr) 6 5 30
Body weight (kg) 30 16 70
TABLE 6.5
CANCER CLASSIFICATIONS AND SLOPE FACTORS
Chemical I EPA Cancer Tumor Site Slope Factor
Group oral/inhalation (mg/kg-dy)-l
oral; inhalation
Trichloroethylene B2 liver/lung 1. lE-2; 1.7E-2
1,1-dichloroethylene C adrenal/kidney 6.0E-1; 1.2E+0
1,1,2-Trichloroethane C liver/liver 5.7E-2; 5.7E-2
Tetrachloroethylene 82 liver/liver, S.1.E-2; 1.8E-3
leukemia
Vinyl chloride A liver/lung 1.9E+0; 2.9E-l
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estimate of the risks calculated from the SF. This approach.
makes underestimation of the actual cancer risk highly unlikely.
Table 6.5 lists cancer classifications and slope factors for
carcinogenic contaminants of concern which had calculated risks
exceeding IE-6.
Honcarcinoaens: Reference Doses (RfDS) have been developed by
EPA for indicating the potential for adverse health effects other
than cancer. RfDs, which are expressed in units of mg/kg-day,
are estimates of chronic daily exposure for humans, including
sensitive individuals, that are thought to be free of any adverse
effects. RfDs are derived from human epidemiological data or
extrapolated from animal studies to which uncertainty factors
have been applied. These uncertainty factors help ensure that
the RfDs will not underestimate the potential for adverse
noncarcinogenic effects to occur. Estimated intake of chemicals
from environmental media can be compared to the RfD for each of
the contaminants.
Table 6.6 lists the oral RfDs for all contaminants of concern
which resulted in hazard quotient of greater than 0.1. No
inhalation reference doses have been verified for any of these
chemicals.
TABLE 6.6
ORAL REFERENCE DOSES
Chemical Effect of Concern Oral Reference Dose
l,l-dichloroethylene liver lesions 9.0E-3
1,2-dichloroethylene hematotoxicity 1.OE-2
Tetrachloroethylene hematotoxicity 1.OE-2 ".
6.1.4
Risk Characteri.zati.on SInnn1Ary
Excess lifetime cancer risks are d~termined by multiplying the
chronic daily intake (CDI) by the slope factor. These risks are
probabilities that are generally expressed in scientific notation
(e.g., 1 x 10-6 or 1E-06). An excess -lifetime-.cancerrisk of 1E-
06 indicates that, as an upperbound estimate, an individual has a
one in one million additional chance of developing cancer in
his/her lifetime as a result of exposure to a site related
carcinogen under the specific exposure conditions at a site.
The potential for noncarcinogenic effects from a single
contaminant in a single medium is expressed as a hazard quotient
(HQ). The HQ is the ratio of the estimated human intake to the
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RfD for a particular contaminant. By adding the HQs for all
contaminants wi~hin a medium and then across all media to which' a
given population may reasonably exposed, the Hazard Index (HI)
can be generated. The HI provides a useful reference point for
assessing the potential significance of exposure to multiple
contaminants across multiple media.
The estimated total carcinogenic risks for the 30 year exposure
to groundwater by an adult in the current land use scenario was
2.2E-6. The maximum risk from oral exposure to any single
chemical was 7.5E-7. For the future residential scenario of
adult exposure to groundwater, the estimated carcinogenic risk
was 2.5E-3. The HI for this exposure scenario was estimated to
be 9.2. Individual chemical risks which exceeded 1E-6 and HQs
which exceeded 0.1 are shown on Tables 6.7 and 6.8.
TABLE 6. 7
SUHMARY OF SIGNIFICANT CARCINOGENIC RISKS
EUTUKE RESIDENTIAL SCEHARIO
Groundwater contaminant Oral Exposure ~sk Inhalation Exposure
Risk-
Trichloroethylene 3.8E-4 3.8E-4
1,1-dichloroethylene 4.8E-4 4.8E-4
1,1,2-trichloroethane 3.SE-6 3.SE-6
Tetrachloroethylene 7.SE-S 7.SE-S
Vinyl chloride 9.8E-4 9.8E-4
~he risk from inhalation exposure to each of the VOCs via daily showering was
assumed to equal the risk from daily ingestion.
TABLE 6.8
SUHMARY OF SIGNIFICANT HOHCARCINOGBHIC BQs
EUTUK£ RESIDENTIAL SCEHARIO
Groundwater contaminant Oral Exposure BQ Inhalation Exposure B~
1,1-dichloroethylene 0.21 0.21
1,2-dichloroethylene 4.0 4.0
Tetrachloroethylene 0.34 0.34
~he BQ from inhalation exposure to each of the VOCs via daily showering was
assumed to equal the BQ from daily ingestion.
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The est~ated carcinogenic risks for exposure to surface soil
were below 1E-6 for the current use scenario of a trespasser as
well as for the future hypothetical residential exposure. The
total est~ated HI for the trespasser in the current use scenario
was less than 0.1. For exposure to surf~ce soil in the future
use residential scenario, the total His were:
o
0.16 for a resident child, age 1 through 5
o
0.02 for a resident adult, 30 year exposure
EPA's targeted carcinogenic risk range for cleanup of Superfund
sites is 1E-04 to 1E-06. Risks less than 1E-06 are deemed
acceptable and those greater than 1E-04 are unacceptable to EPA.
Risks that fall between 1E-04 and 1E-06 mayor may not warrant
action, depending on site-specific factors considered by the risk
manager. Noncarcinogenic HI values greater than 1.0 indicate
that remedial action should be taken. Therefore, the only
identified contamination which poses unacceptable risks is that
of the volatile organic compounds (VOCS) present in the
groundwater.
The risk assessment process contains inherent uncertainties.
Exposure parameters such as frequency and duration of exposure
and ingestion rate of contaminated media can vary between
individuals. Therefore, upperbound values were used to est~ate
exposure, in order to be more protective of human health. Slope
factors and Reference Doses each involve extrapolation to which
conservative uncertainty factors are added in order to be
protective of sensitive humans. Thus, the risk characterization
process strives to min~ize the probability that uncertainties
may result in an underestimation of the actuai health risks that
could result from human exposure to 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 ~inent and substantial
endangerment to public health, welfare, or the environment.
6.2
Environmental (Ecological) Risks
About half of the soon to be closed landfill is barren of
vegetative cover at present. Pine trees have been planted on
closed cells. Some small stands of mixed pine and hardwood as
well as pasture and open fields border the. landfill property. It.
is expected that succession will take place on the landfill in
the years following closure with hardwoods gradually replacing
the pines. A catchment pond is located on the landfill site and
contains some stocked catfish.
A quantitative risk characterization was performed for
potentially exposed birds and mammalian wildlife at the Site.
This was done by comparison of conservatively est~ated daily
doses with published acceptable chronic daily doses of detected
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chemicals to calculate a hazard quotient (HQ). None of the
calculated HQs exceeded the target value of 1.0. Therefore, it"
appears that the site related contamination does not pose a
significant hazard to birds or mammals that might frequent the
Site.
7.0
Descriotion of Remedial Action Alternatives
The Feasibility Study Report presents the results of a detailed
analysis conducted on four potential remedial action alternatives
for the Madison County Landfill Site. This section of the Record
of Decision presents a summary of each of the four alternatives
that are described in the FS Report. Alternative numbering.
corresponds with the FS Report.
Alternative 1 - No Action
Alternative 3 - Institutional Actions, Groundwater Extraction,
Treatment (Air Stripping and Granular Activated
Carbon - GAC), and Reinjection
Alternative 6 - Institutional Actions, Cap Entire Site,
Groundwater Extraction, Treatment (Air
Stripping and GAC), and Reinjection
Alternative 7 - Institutional Actions, Cap YTA Only,
Groundwater Extraction, Treatment (Air
Stripping and GAC), and Reinjection
7.1
Alternative 1 - Ro Action
The Rational Contingency Plan (RCP) requires the development of a
no action alternative as a basis for comparing other
alternatives. Therefore, this alternative would mean no action
would be taken to reduce the risks posed by source and
groundwater contamination at the Site. No restrictions would be
placed on future use of groundwater and no future monitoring
would be performed. Reduction of contamination would take place
only by natural processes.
This alternative would not comply with the preference for
treatment pursuant to SARA; however, through natural processes,
such as dispersion and attenuation, it would eventually achieve
compliance with federal MCLs over a period of time that is in
excess of 1,000 years. This alternative would not prevent the
potential migration of contaminants off-site via surface water or
sediment transport, or leaching of contaminants from the landfill
to the Floridan aquifer. In fact, this alternative would allow
for the continued risk of exposure to contaminated groundwater
should someone install a potable water supply well directly in
the source area.
Since no action is required, this alternative is easily
implemented with no associated costs.
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Alternative 3 - Institutional .Actions, Extraction Wells, Air
Stripping, Carbon Adsorption (GAC), and Reinjection. .
Maior Components of Remedial Alternative:
7.2
This alternative utilizes a.groundwater extraction system with
the extracted groundwater being treated by air stripping and
granular activated carbon (GAC). Based upon the Floridan aquifer
groundwater flow characteristics described in the RI Report,
collection of the contaminated groundwater is feasible using a
groundwater extraction system. The extraction system could be a
single well or multi-well installation~ the type used would be
determined during remedial design. This remedial alternative
consists of the following components:
.
Institutional actions~
Construction of extraction wells~
Installation of groundwater treatment and discharge
(reinjection) system~ and
Construction of a stormwater management system.
.
.
.
Figure 7.1 is a site map depicting the facilities associated with
Alternative 3 and the land areas that would be affected. The
creation of three zones:
.
.
a groundwater recovery zone,
a treated groundwater reinjection zone, and
a stormwater retention area
.
would require acquisition of approximately 4 to 6 acres of
property adjacent to the existing landfill boundary.
Alternative 3 also includes, .but is not limited to the following
institutional actions, which would be implemented by the state
and local government agencies:
.
Access restrictions in the form of fences and signs around
the landfill~
.
Restrictions on future use of the Site to prevent
construction of water supply wells and construction on-
site that would require excavation~
.
Land use ordinances or other measures restricting
construction of water supply wells off;..site in the
vicinity of the landfill~ and
Groundwater monitoring.
.
Access restrictions would be required in order to prevent contact
with the contaminated media. These restrictions may include
fences and signs around the Site, as well as land use ordinances
and deed restrictions. The current site owner, Madison County,
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APPROXIMATE
SCALE
~
o 2j() 500 1000-
Scpol
.
SweROId 14~
County Road 591 ........
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Approximare eXII:m of
radius of influence
P'I~ groundwaa
aeaanent sysrem
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. Wood Burning
. Power Plant
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.-..- Property boundary
- Paved road
- - Potential groundwaaer impact area
. Building / Residential unit
. MonitOring wells to be sampled quanerly
--- Fence
x GroUndwater extraCtion well
. Groundwater injec:tio~ wen
.
Figure 7.1
t
I
AL 1'E.RNA TIVE 3
Location: Madison County Landfill
Madison, Rorida
-41-
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would be required to conduct an inspection of the existing fence
surrounding the landfill and perform any work necessary to make
the existing fence complete and provide on going maintenance of
the fence, as required by Section 403.7255, Florida Statutes and
Rule 17-736, F.A.C.. Also, this rule requires PRPs to supply,
install and maintain warning signs at the Site.
Both deed restrictions and land use ordinances may be used by
state and local government agencies to notify land owners that
groundwater contamination exists beneath the property and
prohibit the construction of new water supply wells in the
affected area. A deed restriction, which is a negotiated
addendum to an existing deed that-indicates that the groundwater
resource below and in close proximity to the property is not
considered safe for potable or other uses, notifies the existing
property owner and any subsequent owners of the groundwater
condition during the time the aquifer is not usable.
Additionally, restrictions on future use of the Site and the area
~ediately downgradient of the YTA would prevent construction of
new water supply wells and prohibit construction that would
require excavation on the site property.
Restricting the use of groundwater in the potentially affected
area can be accomplished by dividing the area into two control
zones as shown in Figure 7.2:
.
Control zone 1 is a 3,000-feet wide corridor with a depth
that begins at monitoring well IT-1 and extends to
monitoring well IT-3. The construction of new water
supply weL~ within control zone 1 would be prohibited.
No water supply wells currently exist in control zone 1.
: ',t\;
Control zone 2 is a 3,000-feet wide corridor situated
between monitoring well IT-3 and extends to a depth of
3,000 feet downgradient of monitoring well IT-1.
Initially, no restrictions would be imposed for
groundwater within control zone 2. However, in the event
that subse~ent monitoring indicates the presence of
contaminanVlevels above MCLs, the restrictions applied to
control zone 1 would also be imposed on control zone 2.
.
Should additional domestic water supply wells in either zone show
contamination during the monitoring period, the owners would be
notified and would be provided with the opportunity to hook-up to
City water in order to prevent further exposure to-the
contaminated groundwater. The restrictions on use of the aquifer
would not be required after EPA certifies achievement of the
performance standards specified in Section 8.1.2.
Groundwater monitoring would be conducted to periodically assess
the degree and extent of groundwater contamination. Monitoring
wells M-2, M-5, IT-13 and monitoring well clusters IT-I, IT-2,
IT-3, IT-4, IT-6, and IT-7 would be monitored quarterly for the
-42-
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----
. i -- -- ~ --. .
Madison r ~
County -
Landfill I
l.p-::.- ,
! ...,J.~1T1 l. .I.T4
j " ITJ I
! II CONTROL f. CONTROL
j ZONE 1 I ZONE 2
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i ~~ IT7.
S~ ! ~ --.....
tnp i ......
~
.-..- Property boundary
- Paved road
- - Potential groundwater impact area
. Building / Residenrial unit
. MonitOring wells ro be sampled quarterly.
--- Fence
A ' , ~OXIMA TE
SCALE
~-
o 2.SO 500 1000
.
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.
Scro1
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County
Road 254
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Swe Road 145
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Figure 7.2
AL TERNA TIVE
INS1TIUTIONAL CONTROLS
Location: Madison County Landfill
Madison. Rorida .
-43-
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chemicals of concern for a period of 25 years or until it is
determined that monitoring is no longer needed. Based o~ the
sampling results generated, EPA may at some point determine that
a less frequent monitoring schedule is appropriate.
A review of the Madison County Landfill site history indicates
that the chemicals of concern were transported about 1,500 to
2,000 feet in the 14 year period between 1971 and 1985. Data
results show that the annual average values of TCE and DCE are
currently approaching the federal/state Maximum Contaminant
Levels (HCLs), which are the accepted health-based concentrations
allowed in groundwater used as a drinking source, and. that vinyl
chloride concentrations have stabilized. Assuming that this
observed trend in attenuation continues, a 25 year period of
monitoring downgradient wells should be adequate to monitor and
document the attainment of MCL concentrations in groundwater.
A groundwater extraction system would be effective in capturing
contaminants entering the Floridan aquifer in the vicinity of the
YTA. Using the numerical model "MOC" (Appendix B of the FS
Report), a one-well extraction system (It would be determined
during remedial design whether a single-well or multi-well
extraction system would be utilized) screened from the top of the
limestone to approximately 50 feet into the limestone, pumping a
total of 250 gallons per minute (gpm) could effectively extract
the contaminated groundwater. The extracted groundwater would be
pumped through a treatment system (air stripper and carbon
adsorption, GAC unit) and discharged into one or more reinjection
wells located downgradient of the extraction well system. If a
reinjection well permit is not attainable other process options
such as infiltration, irrigation and/or direct discharge may be
introduced and further developed as discharge options.
Summarv of Remedial Alternative Evaluation:
The technologies included in Alternative 3 are conventional. and
all necessary equipment is readily available for implementation.
Air stripping and carbon adsorption have been successfully used
for removing similar contaminants from groundwater at several
remediation sites in Florida. Spent carbon would be sent for
recycling at a designated GAC regeneration facility where
adsorbed contaminants would be thermally treated.
Technically, all-of the processes making up this alternative can
be constructed;' operated.- and maintained without ,any unusual
difficulty: ~bwever, administrative difficulties could be
anticipated. First, difficulties could arise in the acquisition
of the required acreage necessary for the construction of the
stormwater management system. Second, the substantive
requirements of a consumptive use permit from the Suwannee River
Water Management District to install the necessary extraction
well system would have to be met ~- -'-Meeting the requirements of a
consumptive use permit is feasible. However, discharge of the
-44-
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treated groundwater could require compliance with other
requirements as. follows:
.
If the contaminated groundwater is a characteristic
hazardous waste (exceeding---So.o ~gll TCE) under RCRA, the
treated groundwater would be prohibited from being
reinjected into the Floridan aquifer without treatment
under the provisions of Chapter 17-28, F.A.C. Treatment
of groundwater to consistently reduce concentrations of
TCE to below the Florida drinking water standards is
feasible.
.
Treated groundwater would be monitored to ensure that
DCE/TCE concentrations are reduced sufficiently and
consistently. The provisions of the monitoring plan could
have a decisive impact on the feasibility of the basic
alternative.
.
If reinjection of the treated groundwater could not be
implemented, then an alternative pathway for disposal of
the effluent from treatment would be necessary. The
political and administrative issues that may be
encountered are unknown. Reuse of treated groundwater in
the State of Florida is a preferred alternative under FDER
policy and may offer an opportunity to secure the remedial
benefits of Alternative 3 without contaminating the
Floridan aquifer. Irrigation and infiltration are
potential alternate process options for discharging
treated groundwater and may be combined into this
alternative, if a reinjection permit can not be obtained.
Based on a cursory evaluation of the anticipated emissions from
the air stripper, air emission controls may not be necessary.
However, a pre-construction review by FDER of the proposed air
stripper would be necessary under the provisions of Chapter 403,
Florida Statutes, and Chapter 17-2, F.A.C. An air permit would
not be necessary as this would be an on-site action under CERCLAi
however, the substantive requirements of such a permit must be
met.
Because the reinjection zone is located off-site, construction
and use of reinjection wells would require a permit or variances
from FDER, pursuant to Chapter 17-28, F.A.C. which governs
underground injection. The treated groundwater would have to
meet Florida's Drinking Water Standards prior to reinjection.
The time required for construction (not implementation) of this
alternative is conservatively estimated to be approximately 2
years from completion of the remedial design.
This alternative would have the potential to achieve the Remedial
Action Objectives (RAOs), including the achievement of the
federal and state MCLs, and be protective of the environment and
human health. The extraction system would have the capability to
-45-
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remediate the contaminated groundwater for an approximate 175,000
square foot area around the southeast corner of the YTA.
The estimated time for this system to meet RAOs at the point of
compliance (500 feet downgradient of monitoring well IT-I) is
estimated to range from 3 to" 5 years. The estimated time
includes the time required for construction of the alternative
(0.5 to 2 years), the time for remediation of the aquifer
(approximately 1.5 years based on modeling results) and the time
required for four quarterly monitoring events (1 year).
The estimated capital costs to be expended over a one to two year
period of construction as presented in the FS are estimated to be .
$3,037,000. Operation & Maintenance (O&M) costs to be expended
over a period of 25 years range between $418,600 and $388,600,
annually. The annual O&M costs are relatively higher for this
alternative because leachate generation from the YTA would
continue and, as a result, the pump and treatment system would
continue to operate until all contaminants of concern have
leached out of the YTA soil; this is estimated to take an
additional 15 years of system operation. The estimated total
present worth cost as presented in the FS would be $7,082,200.
It is noted that for purposes of comparability and practicality,
capital and present worth costs were based on the installation of
a single-well extraction system and a two-well reinjection
system. The actual number and placement of the ~ells within each
system would be determined during remedial design. If EPA
determines that more wells are necessary, the cost would increase
accordingly.
7.3
Alternative 6 -
Institutional Actions, Cap Entire Site,
Extraction Wells, Air Stripping, Carbon
Adsorption (GAC), and Reinjection
Maior Com~onents of Remedial Alternative:
This alternative is identical to Alternative 3 with the addition
of the construction of a clay/soil cap over approximately 52
acres of the Site to include all former closed waste cells.
Alternative 6 utilizes a groundwater extraction system with the
extracted groundwater being treated by air stripping and granular
activated carbon (GAC). The extracti.on, system. could..be.a single
well or multi-well insta'11at'ion;-the type-used. would be
determined during remedial design. This..remedial al,ternative
consists of the following components as shown in Figure 7.3:
.
Institutional actions;
Construction of clay/soil cap over 52 acres;
Installation of a passive gas collection and control
system;
Construction of extraction wells ;-.
Installation of groundwater treatment and discharge
(reinjection) system; and
.
.
.
.
-46-
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APPROXIMA're
SCALE
~-
o 250 500 1000
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.
Stile Rt18d 145
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Approximate extern of
.c . radius of influence :
.
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----
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,
..
.
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.-..- Propeny boundary
- Paved road
- - Potential groundwater impact area
. Building / Residential unit
. MonitOring wells to be sampled quanc:rly
.-. Fence .
~ Area covered by soi1
-------
.
Construction of a stormwater management system.
Madison County already has been ordered by FDER to close the most
recently active waste cell ("the active cell") located on the
northerly portion of the landfill (approximately 9.5 acres, shown
in Figure 7.3). This closure includes construction of a
soil/clay cap designed and constructed in accordance with Rule
17-701, F.A.C., standards. Because Madison County is already
required to complete closure of the active cell before CERCLA
remedial action at the Site is likely to be implemented, closure
of the active cell is not included in this alternative. This
alternative is intended to address the possibility that
contaminants could be released to groundwater from previously
closed waste cells within the Site.
The capping component of Alternative 6 includes capping
approximately 52 acres of land already closed in accordance with
Rule 17-701, F.A.C., including the YTA. The acreage .of
previously closed waste cells have been identified in Madison
County's Landfill Closure Plan prepared by DeRabi and Associates.
Alternative 6 consists of the following components as shown in
Figure 7.3:
.
Acquisition of approximately 43 acres of land for borrow
and construction of the necessary stor.mwater impoundment.
From information obtained from the Madison County plat
map, the acreage could be obtained in three parcels, one
from each of three adjacent land owners. Depending upon
the configuration of facilities that would be required for
Alternative 6, the parcels to be acquired could be:
Two smaller parcels, each ranging from approximately 2
to 6 acres in areas from land east of the YTA; and
One parcel of approximately 30 to 40 acres from land
south of the YTA.
.
Site Preparation including clearing and grubbing the
previously closed waste cells, the YTA, and borrow area (a
total of approximately 95 acres).
Installation of a clay/soil cap that would cQnnect with
the County installed cap, but would require filling of the
County.'.s existing stormwater management u~it (surface
pond) and the transfer of this function to the newly
constructed stormwater control facilities that serve the
entire Site.
.
.
Construction of new stor.mwater control facilities (dikes,
impoundment, and drainage ditches) to serve the entire
Site, requiring approximately 140 .acre-ft capacity.
Stormwater would be stored in a facility constructed in
the borrow area located south of the YTA.
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.
Installation of a passive gas collection and control
system.
.
Construction of a groundwater extraction well system.
Installation of a groundwater treatment system that would
include an air stripper and two GAC columns in series.
.
.
Installation of reinjection well(s) into the Floridan
aquifer.
~ternative 6 also includes, but is not limited to the
institutional actions listed as follows which would be
implemented by state and local government agencies:
.
Access restrictions in the form of fences and signs around
the Site;
.
Restrictions on future use of the Site to prevent
construction of water supply wells and construction on-
site that would require excavation;
Land use ordinances or other measures restricting
construction of water supply wells off-site in the
vicinity of the landfill; and
.
.
Groundwater monitoring.
Each action is fully described under ~ternative 3 in Section
7.2, Components of Remedial ~ternative. As with ~ternative 3,
restricting the use of groundwater in the potentially affected
area can be accomplished by dividing the area into two control
zones as shown in Figure 7.3:
.
Control zone 1 is a 3,000-feet wide corridor with a depth
that begins at monitoring well IT-1 and extends to
monitoring well IT-3. The construction of new water
supply wells within control zone 1 would be prohibited.
No water supply wells currently exist in control zone 1.
.
Control zone 2 is a 3,000-feet wide corridor situated
between monitoring well.IT-3 .and.extends xo A depth of
3,000 feet downgradient of monitoring well IT-1.
Initially, no restrictions would be imposed for
groundwater within control zone 2. However, in the event
that subsequent monitoring indicates the presence of
contaminant levels above MCLs, the restrictions applied to
control zone 1 would also be imposed on control zone 2.
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Should additional domestic water supply wells in either zone show
contamination during the monitoring period, the owners would be
notified and would be provided with the opportunity to hook-up to
City water in order to prevent further exposure to the
contaminated groundwater. The restrictions on use of the aquifer
would not be required after EPA certifies achievement of the
performance standards specified in Section 8.1.2.
Groundwater monitoring would be conducted to periodically assess
the degree and extent of groundwater contamination. Monitoring
wells M-2, M-5, IT-13 and monitoring well clusters IT-I, IT-2,
IT-3, IT-4, IT-6 and IT-7 would be monitored quarterly for the
chemicals of concern for a period of 25 years or until it is
determined that monitoring is no longer needed. Based on the
sampling results generated, EPA may at some point determine that
a less frequent monitoring schedule is appropriate. .
A review of the Madison County Landfill site history indicates
that the chemicals of concern were transported about 1,500 to
2,000 feet in the 14 year period between 1971 and 1985. Data
results show that the annual average values of TCE and DCE are
currently approaching the federal/state Maximum Contaminant
Levels (MCLS), which are the accepted health-based concentrations
allowed in groundwater used as a drinking source, and that vinyl
chloride concentrations have stabilized. Assuming that this
observed trend in attenuation continues, a 25 year period of
monitoring downgradient wells should be adequate to monitor and
document the attainment of MCL concentrations in groundwater.
The process options forming Alternative 6 allow the source of
contamination to be contained while lowering the levels of
contaminants in the contaminated groundwater. The capping
component reduces the volume of leachate generated, thus reducing
the further contamination of the aquifer.
To facilitate capping of the presently closed waste cells, most
of the Site would be cleared and grubbed. Clearing the Site
would involve removing all surface materials including shrubs,
trees, and debris from approximately 52 acres to be capped and
the surface of the borrow area. Approximately a total of 95
acres would have to be cleared and grubbed. After construction
of the new stormwater management facilities, the present pond
would be drained and filled with compacted soil. .
The cap material would be selected in'accordance with Rule 17-
701, F.A.C. and would consist of multiple layers of compacted
clay soil and top soil. The capped area would be graded so that
surface water run-off is directed to the stormwater collection
system. The construction of a low permeability cap over the
landfilled material could result in a build up of VOCs or
methane. Therefore, a passive gas collection and control system
would also be installed as part of this alternative.
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A new stormwater management system would be installed to manage
site run-off, protect the treatment system and reinjection'
well(s) from surface water inflow and prevent run-off of
contaminated stormwater from the remedial project construction
activity. The installation of this_..stormwater management system
would require the acquisition of property around the perimeter of
the Site (See Figure 7.3). "
A groundwater extraction system would be effective in capturing
contaminants entering the Floridan aquifer in the vicinity of the
YTA. Using the numerical model "MOC" (Appendix B of the FS
Report), a single-well extraction system (It would be determined
during remedial design whether a single-well or multi-well
extraction system would be utilized) screened from the top of the
limestone to approximately 50 feet into the limestone, pumping a
total of 250 gallons per minute (gpm) could effectively extract
the contaminated groundwater. The extracted groundwater would be
pumped through a treatment system (air stripper and GAC unit) and
discharged into one or more reinjection wells located
downgradient of the extraction well system. If a reinjection
well permit is not attainable other process options such as spray
irrigation, infiltration or direct discharge may be introduced
and further developed as discharge options.
Summary of Remedial Alternative Evaluation:
The technologies included in Alternative 6 are conventional and
all necessary equipment is readily available for implementation.
Air stripping and carbon adsorption have been successfully used
for removing similar contaminants from groundwater at several
remediation sites in Florida. Spent carbon would be sent for
recycling at a designated GAC regeneration facility where
adsorbed contaminants would be thermally treated.
Alternative 6 is expected to be effective in stopping the release
of contaminated leachate into the downgradient aquifer and would
substantially reduce the levels of contaminants in the
groundwater.
Technically, all of the processes making up this alternative can
be constructed, operated and maintained without any unusual
difficulty; however, administrative difficulties could be
anticipated. First, this alternative would require that a large
area of land be acquired in order to construct the stormwater
management system and other components o£" the.. remedial
alternative. Acquiring the needed property and enacting the
required ordinances prohibiting construction and use of water
supply wells could present some difficulty. Second, the
substantive requirements of a consumptive use permit from the
SRWMD to construct the extraction system would have to be met.
Meeting the requirements of a consumptive use permit is feasible.
However, discharge of the treated groundwater could require
compliance with other requirements as described under Alternative
3, Section 2.7, Summary of Remedial Alternative Evaluation.
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Based on a cursory evaluation of the anticipated emissions from
the air stripper, air emission controls may not be necessary.
However, a pre-construction review by FDER of the proposed air
stripper would be necessary under the provisions of Chapter 403,
Florida Statutes, and Chapter 17-2, F.A.C. An air permit would
not be necessary as this would be an on-site action under CERCLA;
however, the substantive requirements of such a permit must be
met.
Because the reinjection zone is located off-site, construction
and use of reinjection wells would require a permit or variances
.from FDER, pursuant Chapter 17-28, F.A.C. which governs
underground injection. Treated groundwater would have to meet
Florida's Drinking Water Standards prior to reinjection. The
t~e required for construction (not ~plementation) of this
alternative is conservatively estimated to be approximately 2
years.
This alternative would have the potential to achieve 'the Remedial
Action Objectives (RAOs), including the achievement of federal
and state MCLs, and be protective of the environment and human
health. The extraction system would have the capability to
remediate the contaminated groundwater for an approximate 175,000
square foot area around the southeast corner of the YTA.
The institutional measures included in Alternative 6, if
continuously enforced by the state and local government agencies,
would be protective of human health during the period of
remediation. The time estimated for this alternative to meet
RAOs at the point of compliance is estimated to range between 3
and 5 years. The estimated time includes the time required for
construction of the alternative (0.5 to 2.5 years), the time for
remediation of the aquifer (approximately 1.5 years based on
modeling results) and the time required for four quarterly
monitoring events (1 year).
The estimated capital costs to be expended over a one to two year
period of construction as presented in the. FS are estimated to be
$18,390,940. O&M costs to be expended over a period of 25 years
are estimated to range between $409,600 and $109,600, annually.
The est~ated total present worth cost as presented in the FS
would be $20,136,200. It is noted that for purposes of
comparability and practicality, capital and present worth costs
were based on the installation of a single-well extraction system
and a two-well reinjection system.The-a~tua~ number. and
placement of the wells within each system would be determined
during remedial design. If EPA determines that more wells are
necessary, the cost would increase accordingly.
During the first 3 - 5 years, the pump and treatment system would
be constructed and operated. After that t~e period, the
treatment system would be shut down' thereby lowering O&M costs
for the remaining years. The O&M costs remaining would be that
associated with groundwater monitoring.
-52-
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7.4
Al ternati ve 7 - Institutional Actions, Cap YTA, Extraction.
Wells, Air Stripping, Carbon Adsorption
(GAC), and Reinjection.
Maior Components of Remedial Alternative:
Alternative 7 is identical to Alternative 3 with the addition of
an approximate S-acre cap over the YTA portion of the landfill.
Alternative 7 consists of institution actions, groundwater
extraction/treatment, and reinjection in conjunction with capping
of the YTA. This combination of technologies is intended to
control the source of contamination while remediating the
contaminated groundwater. Alternative 7 utilizes a groundwater
extraction system with the extracted groundwater being treated by
air stripping and granular activated carbon (GAC). The
extraction system could be a single well or multi-well
installation; the type used would be determined during remedial
design. Consequently, Alternative 7 consists of the following
components as shown in Figure 7.4:
.
Installation of a clay/soil cap over the YTA;
.
Construction of stormwater control facilities such as
dikes, impoundments, and drainage ditches;
Construction of a groundwater extraction well system;
.
.
Installation of a groundwater treatment system including
an air st~jP.per and two GAC columns; and
Installation, of reinjection welles) into the Floridan
aquifer. .
.
Alternative 7 also' includes, but is not limited to the following
institutional measures which would be implemented by state and
local government agencies:
.
Access res~ctions in the form of fences and signs around
, (
the Site;
.
Restrictions on future use of the Site to prevent
construction of water supply wells and construction on-
site that would require excavation;
Land use ordinances or other measures restricting
construction of water supply wells off-site in the
vicinity of the landfill; and
.
.
Groundwater-monitoring.
Each action is fully described under Alternative 3 in Section
7.2, Components of Remedial Alternative.~ As with Alternative 3,
restricting the use of groundwater in the potentially affected
!
--
-53-
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1- --
APPROXIMATE
SCALE
~-
O~SOO 1(XX)
Scpol
.
Scae RaId 145
1-.. DiJpoooI d
Madison
County
umfill.
IT2 -
.
Approximare exrem of
. radius of influence .
.
.
.
.
......
......
---..
1
,
,
,
,
. .
~
._00- Property boundary
- Paved road
- - Potential groundwater impact area
. Building I Residential unit
. Monitoring wells to be sampled quarterly.
.-. Fence
~ Area covmd by soil-clay cap
:( Groundwater extraetion well
.fA Groundwater inj~on well
t
I
Figure 7.4
AL 1ERNA 11VE 7
.
Location: Madison 'County Landfill
Madison, Florida
-54-
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area can be accomplished by dividing the area into two control
zones as shown in Figure 7.4:
.
Control zone 1 is a 3,000-feet wide corridor with a depth
that begins at monitoring well IT-l and extends to
monitoring well IT-3. The construction of new water
supply wells within control zone 1 would be prohibited.
No water supply wells currently exist in control zone 1.
.
Control zone 2 is a 3,000-feet wide corridor situated
between monitoring well IT-3 and extends to a depth of
3,000 feet downgradient of monitoring well IT-I.
Initially, 'no restrictions would be imposed for
groundwater within control zone 2. However, in the event
that subsequent monitoring indicates the presence of
contaminant levels above MCLs, the restrictions applied to
control zone 1 would also be imposed on control zone 2.
Should additional domestic water supply wells in either zone show
contamination during the monitoring period, the owners would be
notified and would be provided with the opportunity to hook-up to
City water in order to prevent further exposure to the
contaminated groundwater. The restrictions on use of the aquifer
would not be required after EPA certifies achievement of the
performance standards specified in Section 8.1.2.
Groundwater, monitoring would be conducted to periodically assess
the degree and extent of groundwater contamination. Monitoring
wells X-2, X-5, IT-13 and monitoring well clusters IT-I, IT-2,
IT-3, IT-4, IT-6 and IT-7 would be monitored quarterly for the
chemicals of concern for a period of 25 years or until it is
determined that monitoring is no longer needed. Based on the
sampling results generated, EPA may at some point determine that
a less frequent monitoring schedule is appropriate.
A review of the Madison County Landfill site history indicates
that the chemicals of concern were transported about 1,500 to
2,000 feet in the 14 year period between 1971 and 1985. Data
results show that the annual average values of TCE and DCE are
currently approaching the federal/state Maximum Contaminant
Levels (HCLs), which are the accepted health-based concentrations
allowed in groundwater used as a drinking source, and the vinyl
chloride concentrations have stabilized. Assuming that this
observed trend in attenuation continues, a 25 year period of
monitoring downgradient wells should be 'adequate 'to monitor and
document the attainment of MCL concentrations in groundwater.
The process options forming Alternative 7 allow the source of
contamination to be contained while lowering the levels of
contaminants in the contaminated groundwater. The capping
component reduces the volume of leachate generated, thus reducing
the further contamination of the aquifer.
-55-
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To facilitate capping of the southeast corner of the landfill,
the YTA and areas where the stormwater management facilities are
to be constructed would be cleared and grubbed. Clearing the
Site would involve removing all surface materials including
shrubs, trees, and debris. Approximately 11 acres would have to
be cleared and grubbed. .
The YTA cap material Would be selected in accordance with Rule
17-701, F.A.C. and would consist of multiple layers of compacted
clay soil and top soil. The capped area would be graded so that
surface water run-off is directed to the stormwater collection
system.
Since Alternative 7 only provides for capping of the YTA, where
vegetative yard trash and construction debris were placed, no
significant generation of methane gas would be anticipated in
conjunction with capping of the YTA, therefore, no passive gas
collection/control system should be necessary.
A stormwater management system would be installed to manage
stormwater run-off in the vicinity of the YTA, protect the
treatment system and reinjection welles) from surface water
inflow and prevent run-off of contaminated stormwater from the
remedial project construction activity. The installation of this
stormwater management system would require the acquisition of
approximately 6 acres of property immediately south and east of
the YTA.
Groundwater would be extracted at approximately 250 gpm using
submersible centrifugal pumps from an extraction well system
installed on the southeast corner of the YTA. The extracted
groundwater would be pumped through a treatment system (air
stripper and GAC unit) and discharged into one or more
reinjection wells located downgradient of the extraction well
system. If a reinjection well permit is not attainable other
process options such as irrigation, infiltration or direct
discharge may be introduced and further developed as discharge
options.
Summary of Remedial Alternative Evaluation:
The technologies of Alternative 7 are conventional and all
necessary equipment is readily available for implementation. Air
stripping and carbon adsorption have been successfully used to
remove similar contaminants from groundwat~r at several
remediation sites in Florida. Spent carbon would be sent for
recycling at a designated GAC regeneration facility where
adsorbed contaminants would be thermally treated.
Alternative 7 would be effective in reducing the release of
contaminated leachate into the downgradient aquifer and would
remediate contaminated groundwater in the immediate vicinity of
IT-I. During the period of remediation, the institutional
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measures included in Alternative 7, if continuously enforced,
would be protective of human health.
Technically, all of the processes making up this alternative can
be constructed, operated and maintained without any unusual
difficultYi however, administrative difficulties could be
anticipated. First, this alternative would require that
approximately 6 acres of land be acquired in order to construct
the stormwater management system and other components of the
remedial alternative. Acquiring the needed property and enacting
the required ordinances prohibiting construction and use of water
supply wells could present some difficulty. Second, the
sUbstantive requirements of a consumptive use permit from the
SRWMD to construct the extraction system would have to be met. '
Meeting the requirements of a consumptive use permit is feasible.
However, discharge of the treated groundwater could require
compliance with other requirements as described under Alternative
3, Section 2.7, Summary of Remedial ~ternative Evaluation.
Based on a cursory evaluation of the anticipated emissions from
the air stripper, air emission controls may not be necessary.
However, a pre-construction review by FDER of the proposed air
stripper would be necessary under the provisions of Chapter 403,
Florida Statutes, and Chapter 17-2, F.A.C. An air permit is not
necessary as this would be an on-site action under CERCLAi
however, the substantive requirements of such a permit must be
met.
Because the reinjection zone is located off-site, construction
and use of reinjection wells would require a permit or variances
from FDER, pursuant Chapter 17-28, F.A.C. which governs
underground injection. Treated groundwater would have to meet
Florida's Drinking Water Standards. The time required for
construction (not implementation) of this alternative is
conservatively estimated to be approximately 2 years.
This alternative would have the potential to achieve the Remedial
Action Objectives (RAOs), including the achievement of federal
and state MCLs, and be protective of the environment and human
health. The extraction system would have the capability to
remediate the contaminated groundwater for an approximate 175,000
square foot area around the southeast corner of the YTA.
The estimated time for this system to meet RACs at the point of
compliance (500 feet downgradient of monitoring well IT-l) is
estimated to range between 3 to 5 years. The estimated time
includes the time required for construction of the alternative
(0.5 to 2.5 years), the time for remediation of the aquifer
(approximately 1.5 years based on modeling results) and the time
required for four quarterly monitoring events (1 year).
The estimated capital costs to be expended over a one to two year
period of construction are estimated to be $3,445,750. O&M costs
to be, expended over a period of 2S years range between $409,600
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and 109,600, annually. The estimated total present worth cost as
presented in the FS would be $5,191,000. It is noted that for
purposes of comparability and practicality, capital and present
worth costs were based on the installation of a single-well
extraction system and a two-well reinjection system. The actual
number and placement of the wells within each system would be
determined during remedial design. If EPA determines that more
wells are necessary, the cost would increase accordingly.
During the first 3 - 5 years, a pump and treatment system would
be constructed and operated. After that time period, the
treatment system would be shut down thereby lowering O&M costs
. for the remaining years. The O&M costs remaining would be that
associated with groundwater monitoring.
8.0
Comoarative Analvsis of Remedial Action Alternatives
A detailed comparative analysis was performed on the four (4)
remedial alternatives developed during the FS using the nine
evaluation criteria set forth in the NCP. The advantages and
disadvantages of each alternative were compared to identify the
alternative with the best balance among these nine criteria. A
glossary of the evaluation criteria is provided in Table 8.1.
According to the NCP, the first two criteria are labeled
"Threshold Criteria", relating to statutory requirements that
each alternative must satisfy in order to be eligible for
selection. The next five criteria are labeled "Primary Balancing
Criteria", which are technical criteria upon which the detailed
analysis is prima~ily based. The final two criteria are known as
"Modifying Criteri~", assessing the public's and State agency's
acceptance of the ~lternative. Based on these final two
criteria, EPA maym9dify aspects of the specific alternative.
\ .
A summary of the relative performance of each alternative
respect to the nine evaluation criteria and each other is
provided in the following subsections.
with
8.1
Threshold Criteria
~
8.1.1
Overall Protection of Human Health and the Environment
This criterion addresses whether each alternative provides
adequate protection of human health and the environment and
describes how risks are eliminated, reduced, or controlled,
through treatment, engineering controls, _and/or institutional
controls.
All of the alternatives, with the exception of the "No Action"
alternative, would .provide protection of human health and the
environment by eliminating, reducing or controlling risk through
treatment of groundwater contaminants, engineering controls,
and/or institutional controls. Since the no action alternative
does not eliminate, reduce or control any of the exposure
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TABLE 8.1
GLOSSARY OF EVALUATION CRITERIA
THRESHOLD CRITERIA:
Overall Protection of Human Health and the
addresses whether or not a remedy provides
and describes how risks posed through each
el~inated, reduced, or controlled through
controls or institutional controls.
Environment -
adequate protection
pathway are
treatment, engineering
Comoliance with ARABs - addresses whether or not a remedy will
meet all of the applicable or relevant and appropriate
requirements of other federal and state environmental statutes
and/or provides grounds for invoking a waiver.
PRIKARY BALANCING CRITERIA:
Lona-Te~ Effectiveness and Pe~ence - refers to the magnitude
of residual risk and the ability of a remedy to maintain reliable
protection of human health and the environment over t~e once
cleanup goals have been met.
Reduction of Toxicity. Mobility. or Volume Throuah Treatment -
addresses the anticipated performance of the treatment
technologies that may be employed in a remedy.
Short-Te~ Effectiveness - refers to the speed with which the
remedy achieves protection, as well as the remedy's potential to
create adverse ~pacts on human health and the environment that
may result during the construction and ~plementation period.
ImDlementabilitv - is the technical and administrative
feasibility of a remedy, including the availability of materials
and services needed to ~plement the chosen solution.
Cost - includes capital and operation and maintenance costs.
EDIFYING CRITERIA:
State AcceDtance - indicates whether the State concurs with,
opposes, or has no comment on the proposed Plan.
Community AcceDtance - the Responsiveness Summary in the appendix
of the Record of Decision reviews the public comments received
from the Proposed Plan public meeting and the public comment
period.
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pathways, it is deemed not protective of human health or the
environment.
Alternative 1 poses no additional short-term risks to either
human health or the environment, yet overall it provides no
protection. Each of the remaining alternatives, 3, 6 and 7,
would provide adequate ~rotection under both present and future
conditions, by preventing the migration of groundwater
contamination from the YTA and reducing the levels of
contamination in the affected water; however, Alternatives 6 and
7 were found to be most effective because of their incorporation
of both groundwater treatment and source Lmmobilization in the
YTA. Remediation of the groundwater to acceptable health based
levels would be achieved by Alternatives 3, 6 and 7 within 5
years of implementation of treatment; however, Alternative 3
would require a longer period of operation to handle the
continuous leachate generation from the landfill.
8.1.2
Compliance with Applicable or Relevant and Appropriate
Requirements (ARARs) and To-De-Considered Criteria (THes)
This criterion addresses whether or not an alternative will meet
all ARARs of federal and state environmental statutes or provide
a basis for invoking a waiver, as described under CERCLA Section
121 (d). Applicable requirements are those standards, criteria
or limitations promulgated under federal or state law that
specifically address a hazardous substance, pollutant,
contaminant, remedial action, location or other circumstance at a
CERCLA site. Relevant and appropriate requirements are those
that, while not applicable, still address problems or situations
sufficiently similar to those encountered at the site that their
use is well suited to the particular site. To-Be-Considered
criteria (TBCs) are non-promulgated advisories and guidance that
are not legally binding but that should be considered in
determining the necessary level of cleanup for protection of
health and the environment. TBCs do not have the status of
ARARs; however, EPA's approach to determining if a remedial
action is protective involves considering both ARARs and TBCs.
Each alternative was evaluated for compliance with ARARs,
including chemical-specific, action-specific, and locatio~-
specific ARARs, in addition to TBCs. Every potential ARAR and
TBC is presented in Table 8.2. The statutes are broken down in
the table into federal .and stateq regulations. . -
Alternatives' 3, 6 and 7 were equally ranked since each
alternative would attain their respective federal and state ARARs
due to the implementation of institutional controls. These
measures would ensure that there is no potential for future
exposure to groundwater containing contaminant concentrations in
excess of federal and state ARARs promulgated under the SDWA and
Florida Drinking Water Standards, respectivelY9 Alternative 1
would not comply with any identified Site ARARs, and therefore,
will not be ~onsidered in further evaluation.
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Table 8-2
App6cable or Relevant and Appropriate Requirements (ARABs)
Madison County UmdfiO
J.f~disnn, Florida
'Resource Conservation 40 C.F.R f 261.3 ReguJates specific N/A N/A
and Recovery Act chemicals in drinking
(RCRA) water
RCRA 40 C.F.R. f 264 C N/A Relevant and appropriate for on-site N/A
landrill, waste pile or surface
impoundment closure
I ReRA Land Disposal 40 C.F.R. f 268 N/A Restrictions on Land Disposal for N/A
0\ Restrictions (LDRs) chemicals of concern
.....
I
Clean Air Act 40 C.F.R. If 51, 61 N/A Applicable to air emissions from any N/A
and 112 on-site and ofT site treatment
alternatives
Safe Drinking Water Act 40 C.F.R. If 141, 142, Regu]ates drinking water N/A N/A
and 143 supplies using MCLs
40 C.F.R. It 144 and N/A Establishes MCLs for treated emuent N/A
147 being reiIUected into the aquifer,
permit required
Worker Safety and 29 C.F.R. f 1910.120 N/A Worker safety during remedial N/A
Health Protection (OSHA) construction
TN4-94/695814-11-KM!I'BL2-2.DP
-------
Table 8-2
Applicable or Relevant and Appropriate Requirements (ARABs)
Madison County J ~dfi1I
Madison, Florida
iiii:i:iill:I..iliiiiliiii:iii
... .,..',',',",',',".",',','.".",'.','.'.'
..... ,,"',. .. ..""'" ::;::::;':::::;:-:;:'::.'.-:':;:::;:::::
33 UBC 1252 et. seq.
,.;:..:::-::'..;.;::.;:;:;::::.;"'.:::.;.;:;:::;:':::;:;":;:'.:::::::.:.;.:.;'.:.:=',.::.;.:.;';:
.....', ......... ........., ".. ...........
"':r~;:m~~~~i~;;P~~~~#~~~(;\'
........::$~~/......
N/A
.......'I;lt~~~..J~i.i...:.:ii.:...:.
.............i.J:~ell!:".:.....i.
N/A
Clean Water Act
Applicable to discharges into navigable
waters or any work performed in or
affecting the quality of any navigable
waters
Clean Water Act 31 USC 1344 404B
Hazardous Materials 49 C.F.R. U 170 to
ReguJations : 179
I Endangered Species Act 50 C.F.R. f 402
0\
N
I
National Historic 16 USC 470
Preservation Act
N/A
N/A
N/A
N/A
N/A
Applicable to transportation of
hazardous materials
N/A
N/A
N/A
N/A
Applicable to possible
negative impact to
endangered species or
habitat
Applicable to possible effects
of on historic sites and
structures
Florida (FLA) Bolid and
Hazardous Waste
Management Act
FLA Hazardous Waste
Rules
403.702, F.B., et. seq.
I .
N/A
17-730, FAC.
N/A
Applicable to treatment, storage,
transportation and disposal of solid
and hazardous waste
Applicable to treatment, storage,
transportation and disposal of
hazardous waste
N/A
N/A
TA/4-94/595614-U-KMlI'BL2-2.DP
-------
iiJjiiiili!iilliiili:I::Bi:IIi.:!iiijlilli!I;!iji:!
FLA Solid Waste
~anagement Facilities
FLA Air and Water
Pollution Control Act
FLA Water Quality
Standards
I
a-
U)
I
FLA Stormwater
Discharge Regulations
FLA Ambient Air Quality
Standards
FLA Drinking Water
Standards
"
FLA Underground
Injection Control and
Groundwater Discharge
Madison County, Florida
N/A - Not Applicable
Table S.2
AppIQl... or BeIevant and Appropr8de Requiremenbl (ARABs)
Madison County Lendfill
Madison, Florida
17-701, F AC.
403.011, F.S., et. seq.
17-520, F.AC.
17-25, F.AC.
17-2, FAC.
17.550, F.AC.
17-28.700, FAC.
County Oridnances
T A/4-94/696614-11-KM/l'BL2-2.DP
..
. . .. .'''''. ....... .. ..... ... .
N/A Applicable to landfill construction, N/A .
capping and disposal of solid waste
N/A Applicable to discharges to waters of N/A
the State
N/A Groundwater quality standards N/A
N/A Applicable to containment, storage and N/A
discharge of stormwater
N/A Applicable to air emissions from N/A
treatment systems
Regulates drinking water Establishes MCLs for groundwater N/A
supplies using MCLs and emuent from treatment systems
Safe Drinking Water Applicable to any treated emuent N/A
MCLs discharged into groundwater through
an iqjection well. Permit required.
..
N/A N/A N/A
-------
8.2
Primary Balancing Criteria
8.2.1
Long-Te:an Effectiveness and pe:ananence
Long-term effectiveness and permanence refers to the ability of
an alternative to maintain reliable protection of human health
and the environment over time, once cleanup levels have been met.
Alternatives 6 and 7 were found most effective since they include
a capping component which would significantly reduce leachate
generation and the rate of contaminant migration from the YTA.
Alternative 3 would provide long-term effectiveness and
permanence since the treatment process would substantially reduce
the concentrations of contaminants in the groundwater; however,
operation of the treatment system would have to be continued for
approximately 15 years after MCLs are achieved to address the
continued, uncontrolled release of leachate from the YTA.
8.2.2
Reduction of TOxicity, liability, or Volume
This is the anticipated performance of the treatment technologies
an alternative may employ. The degree of reduction of toxicity,
mobility or volume through treatment varies depending on the
methods of groundwater extraction and treatment employed.
Alternatives 3, 6 and 7 would significantly reduce the toxicity
and volume of site contamination, particularly that found in the
groundwater. Since Alternatives 6 and 7 involve containment of
the source material, they would reduce the mobility of the
contaminants by decreasing the amount of stormwater infiltration
entering the YTA, thereby reducing the amount of leachate
generated. This reduction in mobility is not due, however, to
actual treatment of the source material. All factors considered,
Alternatives 6 and 7 were found to be the most effective
alternatives, with Alternative 3 ranking last.
8.2.3
Short-Ta:an Effectiveness
This criterion refers to the period of time needed to completely
achieve protection and any adverse impacts on human health and
the environment that may be posed during the construction and
implementation period until cleanup objectives are achieved. The
following factors were used to evaluate the short-term
effectiveness of each alternative: protection of the community
during remedial actions, protection of workers during-remedial
actions, environmental impacts from implementation of
alternatives, and the time until remedial action objectives are
met.
The construction activities for Alternatives 3, 6 and 7 would
pose a minimal risk to the surrounding community; however, the
groundwater treatment systems utilized in Alternatives 3, 6 and 7
would produce contaminated waste by-products that would require
staging, transport and disposal, or treatment. Handling of these
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waste by-products may pose an additional risk to the community of
off-site transp~rtation and potential spillage.
Additionally, Alternatives 6 and 7 may create unquantified
potential additional risks to remedial workers during clearing,
grubbing and capping activities, through direct contact with
waste materials, inhalation of fugitive dust, and contact with
contaminated groundwater.
In each alternative, the protection of Site personnel would be
afforded by the use of appropriate safety equipment to be worn at
all times while working in contaminated areas. A properly
implemented health and safety program would also provide for
additional protection of personnel.
Adverse impact to the environment would be negligible for each
alternative. Environmental impact, if any, would arise from dust
particulate emissions at the Site and any accidental releases
during off-site transportation of the waste by-products. A
properly implemented health and safety program would address air
monitoring requirements on-site and an off-site Emergency
Contingency Plan would address any off-site release procedures.
8.2.4
Implementability
This is the technical and administrative feasibility of an
alternative, including the availability of goods and services
needed to implement the solution.
All of the alternatives are both technically and administratively
feasible. From a technical perspective, alternatives, 3, 6 and
7, could be constructed, operated and maintained without much
difficulty. Each of these alternatives would require acquisition
of additional land adjoining the Site in order to implement the
remedy; Alternative 3 would require approximately 4 to 6 acres,
Alternative 6 would require approximately 43 acres, and
Alternative 7 would require approximately 6 acres. Alternatives
3 and 7 were found most effective since the required additional
land is minimal in comparison to that required by Alternative 6.
8.2.5
Cost
The following alternatives were assessed on a total cost basis
using the estimated capital cost to perform the remedial work and
the present worth cost for operation and main~enance costs, using
a five percent discounted rate over a 30-year period. Table 8.4
details the capital and 0 & M costs for the 4 remedial
alternatives. It is noted that for Alternatives 3, 6 and 7, cost
estimates were based on the installation of a four-well
extraction system and a two-well reinjection system, although
additional wells may be required, as determined during Remedial
Design.
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TABLE 8.3
Remedial ~ternative Cost ComDarisons
ALTERNATIVE I
'l'OTAL PRESENT
WORTH COST
Alternative 1
$0
Alternative 3
$7,082,200
$20,136,200
Alternative 6
Alternative 7
$5,191,000
Alternatives 3, 6 and 7 were ranked based on the total present
worth costs. Alternative 3 ranked higher than Alternatives 6 and
7 since the groundwater treatment system under Alternative 3
would have to remain in full operation approximately fifteen
years longer because this alternative does not include a capping
component.
Alternative 6 (Cap entire site and Groundwater pump, treatment
and discharge) is the most expensive remedial alternative at
$20.1 million. The cost for Alternatives 3 and 7 are much less
than the cost for Alternative 6 and offer a comparable degree of
protection. Alternative 7 is substantially less expensive than
Alternative 6, yet provides a comparable degree of protection
because of the marginal benefit gained from capping the older
previously closed waste cells.
8.3
Hodifying Criteria
8.3.1
State Acceptance
This indicates whether, based on review of the'RI Report, FS
Report, and Proposed Plan, the U~S. EPA and the State agency
agree on the preferred alternative.
The State of Florida, as represented by the Department of
Environmental Regulation (FDER), has been the support agency
during the Remedial Investigation and Feasibility Study process
for the Madison County Landfill Site. In accordance with 40
C.F.R. S 300.430, FDER, as the support agency, has provided input
during this process. Based upon comments received from FDER, it
is expected that concurrence will be forthcoming; however, ,a
formal letter of concurrence has not yet been received.
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8.3.2
Community Acceptance
This indicates the public's support of a given alternative.
Based on comments made by citizens and government officials at
the public meeting held on September .1, 1992, and those received
during the public comment period, the Agency perceives that the
community believes that the overall selected remedy of capping
the YTA and treating the groundwater would effectively protect
human health and the environment. Each comment received during
the public comment period has been addressed in Appendix A of
this ROD, the Responsiveness Summary.
9.0
Selected Remedv
Based upon consideration of the requirements of CERCLA, the
detailed analysis of the remedial alternatives and public
comments, EPA has selected Alternative 7. Institutional Actions.
Cap YTA Only. Extraction Wells. Air Strippina. Carbon Adsorption.
and Reiniection, as the best course of action for source and
groundwater remediation at the Madison County Landfill Site.
Alternative 7 provides short and long-term protection of human
health and the environment from potential threats associated with
direct contact (ingestion) of the contaminated groundwater, and
provides for immediate initiation of active restoration of the
contaminated groundwater located beneath and in close proximity
to the landfill property.
This alternative utilizes a groundwater extraction system with
the extracted groundwater being treated by air stripping and
granular activated carbon (GAC). The extraction system could be
a single well or multi-well installation; the type used will be
determined during remedial design. The remedial activities for
Alternative 7, as modified by the incorporation of comments
received from the governing state agency, include the following
(See Figure 7.4):
.
Installation of a clay/soil cap over the YTA;
Contingent Installation of a passive gas collection and
control system;
.
.
Construction of stormwater control facilities such as
dikes, impoundments, and drainage ditches;
Construction of a groundwater extract~on well- system;
.
.
Installation of a groundwater treatment system including
an air stripper and two GAC columns; and
Installation of reinjection welles) into the Floridan
aquifer if a permit is obtainable. Should reinjection
prove infeasible, other discharge options such as
infiltration, irrigation and/or direct discharge will be
evaluated.
.
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Alternative 7 also includes, but is not limited to the following
institutional measures which will be implemented by sta~e and
local government agencies:
.
Access restrictions in the form of fences and signs around
the landfill; .
.
Restrictions on future use of the Site to prevent
construction of water supply wells and construction on-
site that would require excavation;
.
Land use ordinances or other measures restricting
construction of water supply wells off-site in the
downgradient flow path from the YTA; and
.
Groundwater monitoring, which will include the
installation of two additional monitoring well clusters.
. Access restrictions will be required in order to prevent contact
with the contaminated media. These restrictions may include
fences and signs around the Site, as well as land use ordinances
and deed restrictions. The current site owner, Madison County,
will be required to conduct an inspection of the existing fence
surrounding the landfill and perform any work necessary to make
the existing fence complete and provide on going .maintenance of
the fence, as required by Section 403.7255, Florida Statutes and
Rule 17-736, F.A.C.. Also, this rule requires PRPs to supply,
install and maintain warning signs around the Site.
Both deed restrictions and land use ordinances may be used by
state and local government agencies to notify land owners that
groundwater contamination exists beneath the property and
prohibit the construction of new water supply wells in the
affected area. A deed restriction, which is a negotiated
addendum to an existing deed that indicates that the groundwater
resource below and in close proximity to the property is not
considered safe for potable or other uses, notifies the existing
property owner and any subsequent owners of the groundwater
condition during the time the aquifer is not usable.
Additionally, restrictions on future use of the Site and the area
immediately downgradient of the YTA will prevent construction of
new water supply wells and prohibit construction on. the site
property that requires excavation while.the.zemedial action is
-undertaken.
Restricting the use of groundwater in the potentially affected
area will be accomplished by dividing the area into two control
zones as shown in Figure 7.4:
.
Control zone 1 is a 3,000-feet-wide corridor with a depth
that begins at monitoring well IT1 and extends to
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.
monitoring well IT3. The construction of new water supply
wells within control zone 1 would be prohibited. No water
supply wells currently exist in control zone 1.
Control zone 2 is a 3,000-feet wide corridor situated
between monitoring well IT3 and extends to a depth of
3,000 feet downgradient of monitoring well IT1.
Initially, no restrictions would be imposed for
groundwater within control zone 2. However, in the event
that subsequent monitoring indicates the presence of
contaminant levels above MCLs in downgradient point of
compliance wells, the restrictions applied to control zone
1 would also be imposed on control zone 2. Also, EPA will
consult with the SRWMD prior to their allowance of any
potable well installations in control zone 2 during time
of aquifer remediation.
Should additional domestic water supply wells in either zone show
contamination during the monitoring period, the owners would be
notified and would be provided with the opportunity to hook-up to
City water in order to prevent further exposure to the
contaminated groundwater. The restrictions on use of the aquifer
would not be required after EPA certifies achievement of the
performance standards specified in Section 8.1.2.
Two additional groundwater monitoring well clusters will be
installed as part of this remedial action. These well clusters
will be located along the eastern landfill property boundary to
monitor other pot~tial source areas located outside of the
capped YTA area. '!Groundwater monitoring will be conducted to
periodically assess, the degree and extent of groundwater
contamination. Monitoring wells M-2, M-5, IT-13 and monitoring
well clusters IT-l; IT-2, IT-3, IT-4, IT-6, IT-7 will be
monitored quarterly for the chemicals of concern for a period of
25 years or until it is determined that monitoring is no longer
needed. Additionally, monitoring well M-l, the two newly
installed monitoring wells, and the four newly installed
replacement domes~ wells, located in close proximity to the
existing contaminai~d domestic wells, will be monitored on the
same schedule under-this remedial action. Based on the sampling
results generated, EPA may at some point determine that a less
frequent monitoring schedule is appropriate. .
A review of the Madison County Landfill site history indicates
that the chemicals of concern were transported about 1,500 to
2,000 feet in the 14 year period between 1971 and 1985. Data
results show that the annual average values of TCE and DCE are
currently approaching MCL concentrations and that vinyl chloride
concentrations have stabilized. Assuming that this observed
trend in attenuation continues, a 2S year period of monitoring
down gradient well'iL.should be adequate to monitor and document the
attainment of MCL concentrations in gro~dwater.
!
.
.
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.,
"
-------
The process options forming ~ternative 7 allow the source of
contamination to be contained while lowering the levels of .
contaminants in the "contaminated groundwater. The capping
component will reduce the volume of leachate generated, thus
reducing the further contamination of the aquifer.
This alternative requires the acquisition of approximately 6
acres of land in the vicinity of the YTA in order to construct
the stormwater management system and other components of the
remedial action.
To facilitate capping of the southeast corner of the landfill,
the YTA and areas where the stormwater management facilities are
to be constructed will be cleared and grubbed. Clearing the Site
involves removing all surface materials including shrubs, trees,
and debris. Approximately 11 acres has to be cleared and
grubbed.
The YTA cap material will be selected in accordance with Rule 17-
701, F.A.C. and will consist of multiple layers of compacted clay
soil and top soil. The cap material will be designed in
accordance with Rule 17-701, F.A.C. The capped area will be
graded so that surface water run-off is directed to the
stormwater collection system.
Since ~ternative 7 only provides for capping of the YTA, where
vegetative yard trash and construction debris were placed, no
significant generation of methane gas is anticipated in
conjunction with capping of the YTA; therefore, no passive gas
collection/control system should be necessary. In the event that
monitoring indicates methane gas generation has occurred, a
passive gas collection and control system will be designed and
installed at the Site in accordance with Rule 17-701, F.A.C.
A stormwater management system will be designed and installed
according to state and federal regulations to manage stormwater
run-off in the vicinity of the YTA, to protect the treatment
system and reinjection welles) from surface water inflow and to
prevent run-off of contaminated stormwater. from the remedial
project construction activity. The installation of this
stormwater management system requires the acquisition of
approx~ately 6 acres of property immediately south and east of
the YTA.
Groundwater will be extracted atapproximate.~y ~~Q gpm using
submersible centrifugal pumps from an extraction well system
installed on the southeast corner of the YTA. The extracted
groundwater will be pumped through a treatment system (air
stripper and GAC unit) and discharged into one or more
reinjection wells located downgradient of the extraction well
system. If a reinjection well permit is not attainable other
process options such as infiltration," .irrigation and/or direct
discharge will be introduced and further developed as discharge
options. .
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Referring to Table 8.2, the site-related contaminants of concern
have Maximum Contaminant Levels (MCL) as promulgated. under the'
Safe Drinking Water Act (40 C.F.R. 141,143) and Florida's
Drinking Water Standards. The MCLs for the groundwater chemicals
of concern are listed in Table 5.1 and will be used as the
performance standards for each contaminant at and beyond the
points of compliance. Pumping and treating will continue until
the remediation levels for these chemicals are achieved. Prior
to reinjection, the treated groundwater must meet the State and
Federal drinking water standards.
Technically, all of the processes making up this alternative can
be constructed, operated and maintained without any unusual
difficulty; however, administrative difficulties could be
anticipated. First, this alternative requires that approximately
6 acres of land be acquired in order to construct the stormwater
management system and other components of the remedial
alternative. Acquiring the needed property and enacting the
required ordinances prohibiting construction and use of water
supply wells could present some difficulty. Second, the
substantive requirements of a consumptive use permit from the
SRWMD to construct the extraction system must be met. Meeting
the requirements of a consumptive use permit is feasible.
However, discharge of the treated groundwater could require
compliance with other requirements as described under Alternative
3, Section 2.7, Summary of Remedial Alternati-ve Evaluation.
The air stripper will be designed and constructed in accordance
with Rule 17-2, Florida's Air Quality Standards. A pre-
construction review by FDER of the proposed air stripper will be
necessary under the provisions of Chapter 403, Florida Statutes,
and Chapter 17-2, F.A.C. An air permit is not necessary as this
will be an on-site action under CERCLA; however, the substantive
requirements of such a permit must be met.
Because the reinjection zone is located off-site., construction
and use of reinjection wells will require a permit or variances
from FDER, pursuant Chapter 17-28, F.A.C. which governs
underground injection. The time required for construction (not
implementation) of this alternative is conservatively estimated
to be approximately 2 years, from completion of the remedial
design.
This alternative has the potential to achieve the Remedial Action
Objectives (RAOs), including the. achievement of federal and state
MCLs, and be protective of the environment and human health. The
extraction system has the capability to remediate the
contaminated groundwater for an approximate 175,000 square foot
area around the southeast corner of the YTA. Should subsequent
monitoring identify other sources of groundwater contamination,
the remedial action will be modified as necessary to address the
additional areas of contamination.
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1-
The estimated time for this system to meet RAOs at the point of
compliance (500 feet downgradient of monitoring well IT-~) is
estimated to range between 3 to 5 years. The estimated time
includes the time required for construction of the alternative
(0.5 to 2.5 years), the time for remediation of the aquifer
(approximately 1.5 years based on modeling results) and the time
required for four quarterly monitoring events (1 year).
For purposes of comparability and practicality, capital and
present worth costs were based on the installation of a single-
well extraction system and a two-well reinjection system. The
actual number and placement of the wells within each ~ystem will
. be determined during remedial design. If EPA determines that
more wells are necessary, the cost will increase accordingly.
Also, the additional installation of two monitoring well clusters
and the expanded groundwater monitoring program were.not
accounted for in the cost analysis presented in the FS Report.
The total present worth cost of Alternative 7 will increase
proportionally with the additional components added to the
selected remedy. Table 9.1 details the cost analysis summary
for Alternative 7 as presented in the Feasibility Study. The
estimated capital costs to be expended over a one to two year
period of construction are estimated to be $3,445,750. O&M costs
to be expended over a period of 25 years range between $109,600
and 409,600, annually. The estimated total present worth cost is
$5,191,000. As noted, these costs will be adjusted accordingly
during remedial action.
During the first 3
be constructed and
have been met, the
lowering O&M costs
remaining would be
- 5 years, the pump and treatment system will
operated. After the performance standards
treatment system will be shut down thereby
for the remaining years. The O&M costs
that associated with groundwater monitoring.
Long-term groundwater operation and maintenance activities will
include quarterly monitoring for a minimum of five, years. At
that time EPA will evaluate the feasibility of using a less
frequent monitoring schedule for the duration of the 25-year
long-term groundwater monitoring program. Long-term operation
and maintenance requirements such as routine maintenance checks
are expected for the recommended alternative, including the
integrity of the installed cap. Monitoring will determine the
effectiveness of the clay/soil cap and the implemented pump and
treatment system at-reducing migration of contaminants in the
groundwater and remediatinggroundwater-to.meet.the performance
standards. An Operation and Maintenance Plan will be developed
during the Remedial Design/Remedial Action tasks.
Desian Considerations
The goal of this remedial action is to restore groundwater to its
beneficial use, which is, at this' Site, as.a drinking water
source. Based on information obtained during the RI and on a
careful analysis of all remedial alternatives, EPA believes that
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Table 9.1
Coat £ltl..t. R818d111 A1t.rnatlvt 7
F..llbl1lt1 StYdy MadIson County Llndfll1
Madflon (dMIt1. Fl 01'1 d8
Tllk DescrIptIon
QuantIty/
~tt PrIce
Totll
(I)
I. CAPITAL COSTS (C.P Ylrd Trllh Aru. 6roundMttr btrlCtlon.
Trut88nt Ind ReinjectIon. Inltltutlon.l "'Iurea)
A. II..,... lIeconltruct Fenc.
8. 0t8d Rntrlctlon.
C. EnlCt 6roundMt.r Ordl n&IIC8
D. ConnectIon Coltl Future U8era
£. Lind Surve1 AQul,.. "'1 Eatlt.
F. Lind AQullltlon
6. 1I-.:f111 AlaIn Ooc..."ta
H. Trutlbl11ty StYdy
I. c.P Ylrd Trllh Aru
o C1..r Ind 6rub
o G.I CollectIon
o 2 Foot c.p
o Sand Orlln LI~r
o Orllnl91 s..1..
o 8I11nct 0' Sol1 Covtr
o 5011. Ftrtl11ztr. Mu1ch
J. Grou"..ttr Trutl8nt S1It-
o I18COyery Wel1 S11t-
o InjectIon We111
o Tl'MtNfIt S1It-
K. Project O"lce Fac111t1el
L. Project £ntlneerlng/Ma"'v-nt
o 11...:1111 DeIIgr1
o Project Ma".ger
o HIS 0"1 cer
o T8Cmlclln
... ContIngency 101
3000 1.'.
Job
Job
3~ . 1248
Job
5.75 Acre.
Jot!
Job
1
2
(2 ~ra)
TOT At.
.
:1. ANNUAL OIM COST
L. S.
48 . 120,000 ;11
5-3 ..11 clult.,..-
A. Mllntlln Ftnce
B. Cost 0' Furnlshln; County Wlttr
C. OUlrterly Groundwlttr Monltorln;
O. PeriodIc Halellte Inspectionl
E. Treltment Syat81 Monltorln; (3.5 yelr,)
F. Operlte/Mllntlln DIke Drllnl;t Sy,t81
5. Disgolll/lIepllcement Co.t Carbon (3.5 yelr.)
H. Ooerltion/Milntenlnce Groundwlter Trelt Sy,t81 (3.5 yelr,)
I. PrOJ8Ct Of'l,t Utllltltl Supplle. (2 ytlrs)
For 2 yelr,
For 1.5 yerll
For 21.5 ytlrs
-73-
122.900.00
11.000.00
125.000.00
1I.~00.00
15.000.00
IZO.~OO.oo
'80.000.00
sa.900.00
123.100.00
121. 000.00
$335.000.00
$33.900.00
1131.100.00
114&.300.00
11.100.00
'100.000.00
1205.000.00
1702.900.00
'15.000.00
$380.000.00
S~ZO.ooo.oo
S210.ooo.oo
S14O.ooo.oo
$313.250.00
$3.4&5.750.00
S1.000.00
S6.100.00
'95.500.00
S2.000.00
$200.000. 00
S5.000.00
S20.000.00
S50.000.00
$30.000.00
S409.6oo.00 oer y'lr
S379,600.00 p~r 1'11'
S109,600.00 per 1'11'
-------
the selected alternative will achieve this goal. It may become
apparent, during implementation or operation of the grou~dwater
extraction system and its modifications, that contaminant levels
have ceased to decline and are remaining constant at levels
higher than the remediation goal over some portion of the
contaminated plume. In such a case, the system performance
standards and/or the remedy may be reevaluated by EPA.
The selected remedy will include groundwater extraction for an
estimated period of 5 years, during which the system's
performance will be carefully monitored on a regular basis and
adjusted as warranted by the performance data collected during
operation. To insure that the design of the system is optimized, .
modifications may be considered prior to invoking contingency
measures. These modifications may include but are not limited to
the following:
a)
at individual wells where cleanup goals have been
attained, pumping may be discontinued;
b)
alternative pumping at wells to eliminate stagnation
points;
c)
pulse pumping to allow aquifer equilibration and to
allow adsorbed contaminants to partition into'
groundwater;
d)
.,
installation of additional extraction wells to
facili tate'".or accelerate cleanup of the contaminant
plume and~r mitigate additional source areas; and
implement' Q,;ther measures to address addi tional source
areas as deemed necessary.
e)
To ensure that cleanup goals continue to be maintained, the
aquifer will be monitored at those wells where pumping has ceased
on a quarterly basis until EPA determines that a less frequent
monitoring schedu~is acceptable, for a period of 25 years.
'{
10.0 Statutory DeteJ:JDinations
Under its legal authority, EPA's primary responsibility at
Superfund sites is to undertake remedial actions that achieve
adequate protection of human health and the environment. In
addition, Section 121 of CERCLA establishes. several..other
statutory requirements and preferences. These specify that, when
complete, the selected remedial action for this Site must comply
with applicable or relevant and appropriate environmental
standards established under federal and state environmental laws
unless a statutory waiver is justified. The selected remedy must
also be cost effeq~ive and utilize permanent solutions and
alternative treatment technologies or resource recovery
technologies to the maximum extent practicable. Finally, the
statute includes a preference for remedies that employ treatment
~ .'
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1
I
I
I
that permanently and significantly reduces the toxicity, mobility
or volume of ha~ardous wastes as their principle element. The'
following sections discuss how the selected remedy for this Site
meets these statutory requirements.
10.1
. -. -
Protection of Human Health and the Environment
The selected remedy satisfies the requirement of CERCLA Section
121 to protect human health and the environment by eliminating
risks posed through each exposure pathway and to each population
through treatment. It ensures adequate protection of human
health and the environment. The site risk will be reduced to
well below the 1E-6 risk range for carcinogens.
The selected remedy of implementing institutional actions,
capping the YTA, and treating (air stripping/carbon
adsorption)/reinjecting the groundwater protects human health and
the environment through the imposition of institutional controls,
groundwater restoration, and future site monitoring. Restricted
access to both the Site and the groundwater below eliminates the
threat of direct contact (ingestion) of the VOC-contaminated
groundwater to current and future landowners in the vicinity of
the Site. Additionally, implementation of the groundwater
treatment system will eliminate the potential ingestion threats
to downgradient receptors, and will restore the groundwater to
levels deemed acceptable by EPA and the State.
Implementation of Alternative 7 will not pose any unacceptable
short-term risks or cross-media impacts to the Site, the workers,
or the community that cannot be readily controlled. Potential
risks associated with transportation of waste by-products and
discharge of treated groundwater off-site will be minimized by
following the respective Health & Safety and Discharge Permit
Plans.
Compliance with Applicable or Relevant and Appropriate
Requirements (ARARs) and To-Be-Considered Criteria (TBCs)
Section 121 (d)(2)(A) of CERCLA incorporates into the law the
CERCLA Compliance Policy, which specifies that Superfund remedial
actions must meet any federal and state standards, requirements,
criteria,' or limitations that are determined to be legally
applicable or relevant and appropriate requirements (ARABs).
Also included is the provision that state ARARs must be met if
they are more stringent than federal requirements.
10.2
Applicable requirements are those standards, criteria or
limitations promulgated under federal or state law that
specifically address a hazardous substance, pollutant,
contaminant, remedial action, location or other circumstance at a
CERCLA site. Relevant and appropriate requirements are those
that, while not applicable, still address problems or situations
sufficiently similar to those encountered at the site that their
use is well suited to the particular site. To-Be-Considered
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f
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criteria (TBCs) are non-promulgated advisories and guidance that
are not legally binding but that should be considered in.
determining the necessary level of cleanup for protection of
health and the environment. TBCs do not have the status of
ARARs; however, EPA's approach to determining if a remedial
action is protective involves considering both ARARs and TBCs.
All potential ARARs and TBCs for treating contaminated
groundwater at the Madison County Landfill are presented in Table
8.2. Where VOCs and inorganic constituents affect groundwater,
the Safe Drinking Water Act (SDWA) provides potential ARARs for
establishing cleanup goals, i.e., Maximum Contaminant Levels
(HCLs). In addition, the State of Florida has established
guidance concentrations for specific Volatile Organic Compounds,
which, when more stringent than the federal MeL, have been
selected as the cleanup goals for this project.
The recommended alternative was found to meet or exceed the
following ARARs and TBCs selected from Table 8.2 which directly
apply to the selected remedy, as discussed below.
Chemical-Soecific ARABs:
[ .
o
Safe Drinking Water Act, SDWA (40 C.F.R. SS 141, 142 and
143), which specifies the HCLs for the contaminants of
concern that will be applicable as the remediation levels
for contaminated groundwater. However, should the state
drinking water standard under 17-550, F.A.C. for a
particular contaminant be more stringent, the state
standard will be used as the remediation level.
o
SDWA (40 C.F.R. is 144.12, 144.13 and 147), which applies
to the injection of treated effluent into the Floridan
aquifer. A permit will be required since reinjection will
take place off-site.
Resource Conservation and Recovery Act, RCRA (40 C.F.R. S
261.31), which applies to chemical concentrations in
groundwater.
o
o
Florida (FLA) Drinking Water Standards (17-550, F.A.C.),
which establishes contaminant concentrations acceptable in
potable water. These standards will be applicable when
more stringent than the federal" HCL. -' .
FLA Underground Injection Control and Groundwater
Discharge (17-28.700, F.A.C.), which applies to the
treated effluent being reinjected into the Floridan
aquifer. These standards will be applicable when more
stringent than the federal standards.
o
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Location-Soecific ARABs:
Endangered Species Act (50 C.F.R S
that federal agencies ensure that
jeopardize the continued existence
endangered species.
Action-Soecific ARARs:
o
402), which requires
their actions do not
of a threatened or
o
RCRA (40 C.F.R. 5 264 Subtitle C for Landfill Closure),
which applies to the closure of the YTA and maintenance of
the cap should any portion of the comparable state
regulation be waived.
o
SDWA (40 C.F.R. 55 144.12, 144.13 and 147), which applies
to the reinjection of treated effluent into the Floridan
aquifer. A permit will be required since reinjection will
take place off-site.
o
Clean Air Act, CAA (40 C.F.R. 5 61, CAA 5 112), which
applies to air emissions from treatment technologies, such
as air stripping. Also, 40 C.F.R. 55 51.160 through 51.164
describe the pre-construction and permitting process for
air emissions. Since treatment will occur on-site, only
the substantive requirements of PSD permit must be met.
o
Hazardous Materials Regulations (49 C.F.R 55 170 to 179),
which applies to transportation of hazardous materials or
waste by-products, such as the spent carbon generated
during groundwater treatment.
o
FLA Solid Waste Management Facilities (17-701, F.A.C.),
which applies to closure of the YTA and maintenance of the
cap. These standards are applicable since they are more
stringent than the federal regulations under RCRA 40
C.F.R. 5 264.
o
FLA Drinking Water Standards (FDER 17-550), which
establishes MCLs for groundwater and effluent from
treatment systems. These standards will be applicable
when more stringent than the federal regulations under the
SDWA.
o
FLA Ambient Air Quality Standards (17-2, F.A.C.), which
applies to air emissions from treatment technologies, such
as air stripping. These standards will be applicable when
more stringent than the federal regulations under the CAA.
FLA Underground Injection Control and Groundwater
Discharge (17-28.700, F.A.C.), which is applicable to
treated effluent discharged into groundwater through a
reinjection well. Permit required. These standards will
o
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be applicable when more stringent than the federal
standards for reinjection.
o
FLA Solid and Hazardous Waste Management Act (403.702,
F.S., et. seg.), which appl~~sto the transportation and
disposal of hazardous waste. These standards will be
applicable when more stringent than the federal
regulations under 49 C.F.R. SS 170 to 179.
FLA Hazardous Waste Rules (17-730, F.A.C.), which applies
to the treatment, storage and disposal of hazardous waste.
These standards will be applicable when more stringent
than the federal standards. '
o
o
FLA Water Quality Standards (17-520, F.A.C.), which
establishes groundwater quality standards that will be
applicable to the treated effluent when more stringent
than the federal regulation.
o
FLA Stormwater Discharge Regulations (17-25, F.A.C.),
which applies to the containment, storage and discharge of
stormwater. These standards will be applicable when more
stringent than the federal regulation.
FLA Warning Sign Rule (17-736, F.A.C.), which applies to
the installation and maintenance of warning signs around a
NFL site.
o
Other Criteria To-Be Considered:
10.3
The RCRA Land Disposal Restrictions (LDRs) (40 C.F.R. S 268
D), are not applicable or relevant and appropriate
requirements for this project because the waste streams (the
solid, domestic trash and the hazardous chemicals) were not
mixed during disposal. The hazardous constituents were placed
in drums then buried in the YTA. Also, based on the RCRA
definition of "placement," LDRS will not be triggered by any
excavation, clearing, and/or grubbing activities that will
take place during remedial action at the Site. The borrow
material that will be used during the capping activities has
not been mixed with the hazardous source material, and
therefore, will not trigger LDRs during placement.
Also, EPA has developed a policy for control of emissions from
air stripper operations at CERCLA sites,-entitledControl of
Air Emissions from Superfund Air Striooers at Suoerfund
Groundwater Sites, June 15, 1989 (OSWER Directive 9355.0-28)
which should be used as guidance for control of emissions
generated during remedial action.
Cost Effectiveness
This alternative affords a higher degree of overall effectiveness
in not only protecting the public against direct exposure but in
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removing the threat of a future release of contaminants. The
estimated total .present worth cost of this alternative is $5.1 .
million (including operation and maintenance).
The selected remedy affords overall effectiveness proportional to
its cost, such that the remedy represents a reasonable value for
the money. When the relationship between cost and overall
effectiveness of the selected remedy is viewed in light of the
relationship between cost and overall effectiveness afforded by
the other alternatives, the selected remedy appears to be
cost-effective.
10.4
Utilization of Pe~ent Solutions and Alternative .
Treatment Technologies (or Resource Recovery Technologies)
to the M;nrhmm Extent Practicable
u.s. EPA has determined that this remedy is the most appropriate
cleanup solution for remediating the source and groundwater
contamination at the Madison County Landfill Site and that it
provides the best balance among the evaluation criteria for
remedial alternatives evaluated. This remedy provides effective
protection in both t~e short and long-term to potential human and
environmental receptors, is readily implemented, and is cost
effective.
The selected remedy satisfies the requirement of section 121 to
utilize permanent solutions and alternative treatment
technologies or resource recovery technologies to the maximum
extent practicable.
10.5
Preference for Treatment as a Principal Element
This remedy meets the statutory requirement to utilize permanent
treatment technologies to the maximum extent practicable. The
selected remedy satisfies the preference of CERCLA section 121
for treatment as a principal element.
Because wastes will remain in the YTA beneath the cap above
health-based levels, EPA will review the Site at least every five
years to ensure the effectiveness of the treatment process and
the integrity of the cap.
11.0
Documentation of Significant Chanaes
The Proposed Plan for the Madison County Landfill Site was
released to the public on August 24, 1992. The Proposed Plan
identified Alternative 7, Institutional Actions, Cap YTA Only,
Extraction, Treatment (Air Stripping/Carbon Adsorption (GAC»,
and Reinjection, as the preferred alternative for site
remediation. EPA reviewed all written and verbal comments
submitted during the public comment period. Upon review of these
comments, it was determined that no significant changes to the
remedy, as originally identified in the Proposed Plan, were
necessary.
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