United States
Environmental Protection
Agency
Office of
Emergency and
Remedial Response
EPA/ROD/RO4-89/054
September 1989
Superfund
Record of Decision
Sydney Mine Sludge Ponds, FL
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5027~101
REPORl\,DOCU~ENTATION 1'. REPORTNO. 12-
PAGE EPA/ROD/R04-89/054
4. folie and Subtitle
SUPERFUND RECORD OF DECISION
Sydney Mine Sludge Ponds, FL
First Remedial Action ~ Final
7. A.u1hor(a'
3. R8cip1ent. Ac-.Ion No.
50 Aapart Da18
09/29/89
8.
8. P8rf0nninll Organization RaJJ'. No.
9. Pel10nning Orgalnlzatlon Nama and AddIwu
10. Projac:tlTulllWorII UnIt No.
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.
11. ConIr8c1(C). Gnnt(G) No.
Ic)
IG)
12. Sponsoring Organlullon Nama and AdIhM
U.S. Environmental Protection
401 M Street, S.W.
Washington, D.C. 20460
13. Type of R~. Period eoWt8d
Agency
8001000
14.
15. Supplement.,., No..
16. AbstrlC1 (Umlt: 200 _rd.)
The Sydney Mine Sludge Ponds site occupies 9.5 acres of a 1,700-acre former phosphate
mining site in Brandon, Hillsborough County, Florida. From 1973 to 1981 the county
rented the site for disposal of septic wastes, waste automotive oils, grease trap wastes,
and manufacturing cutting oils. An estimated 16 million gallons of wastes were deposited
, three small pits. An EPA site investigation in 1979 identified organics and heavy
tal contamination in monitoring wells near the waste pits. Sampling was also performed
In Turkey Creek which flows through the mine site about a mile from the waste pits.
Upstream and downstream sediment samples exhibited elevated levels of metals. Disposal
operations ended in September 1981 when the State denied issuance of a second operation
permit for the site. The State and county began a two-phase cleanup effort in 1984. The
first phase included construction of a slurry wall around the waste pits: excavation and
onsite incineration of approximately 10,900 cubic yards of pit wastes: and pumping and
onsite treatment of ground water. The second phase included excavation' of approximately
15,000 cubic yards of contaminated soil. with onsite treatment by air-drying followed by
offsite disposal. This operable unit addresses ground water contamination at the site.
The primary contaminants of concern affecting the ground water are VOCs including
benzene, tolu~ne, TCE, and xylenes.
17. Document Anlly8l. L Deacrlptora
Record of Decision - Sydney Mine
First Remedial Action - Final
Contaminated Medium: gw
Key Contaminants: VOCs (benzene,
Sludge Ponds, FL
I
toluene, TCE, xylenes)
b. Iden1i1ier8l~Ended Temw
-
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- vaillbitity Sta1ement
I 111. S8cvtty CIau (ThIa Report)
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21. No. 0' pagea
46
22. Price
ISee ANSI-Z3I1.18)
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Depemwntof Co-
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..
16.
Abstract (Continued)
Syaney Mine Sludge Ponds, FL
~A/ROD/R04-89/054
The selected remedial action for this site includes continued ground water pumping with
on~ite treatment by air stripping and spray irrigation on land adjacent to the waste
disposal site; evaluation of the existing ground water pumping and treatment system and
implementation of any necessary modifications to improve the operation; continued ground
water monitoring; and implementation of deed and ground water use restrictions. The
estimated present worth cost for the selected remedy is $2,448,000 which includes an
annual O&M cost of $576,000.
. ..
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Record of Decision
Dec'1aration
Site Name and Location:
Sydney Mine Sludge Ponds
Hillsborough County, Florida
Statement of Basis and Puroose:
This decision document presents the selected remedial action for th~
Sydney Mine Sludge Ponds Site in Hillsborough County, Florida,
developed in accordance with the Comprehensive Environmental,
Response, Compensation, and Liability Act of 1980 (CERCLA), as
amended by the Superfund Amendments and Reauthorization Act of 1986
. (SARA), and, to the extent practicable, the National Oil and
Hazardous Substances Pollution Contingency Plan '(NCP). This decision
document explains the factual and legal basis for selecting the .
remedy for the site.
The State of Florida has concurred on the selected remedy. The
information supporting this remedial action decision is contained in
the administrative record for this site.
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 unacceptable risk to public
health, welfare, or the environment.
Description of the Selected Remedv:
The remedy selected by EPA will be conducted in one opetable unit.
The major components of the selected remedy for the operable unit are
as follows a
COD~inued operation of the existing ground-water recovery
and. treatment system
Continued monitoring (sampling and analysis) of the ground
water
Evaluation and modification, if necessary, of the existing
ground-water recovery and treatment system to improve its
effectiveness and efficiency
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.Declaration:
The selected remedy is protective of human health and the
environment, complies with Federal and State requirements that are
legally applicable or relevant and appropriate to the remedial
action, and is cost-effective. A waiver can be justified for any
Federal and State applicable or relevant and appropriate require~ents
that will not be met. This remedy utilizes permanent solutions and
alternative treatment technologies, to the maximum extent
practicable, and it satisfies the statutory preference for remedies
that employ treatment that reduce toxicity, mobility, or volume as
their principal element.
, .
Because this remedy may result in hazardous substances remaining
on-site above health-based levels, the five-year facility review
apply to this action. .
. ;t1 c. ~ ~ f . '7- 2"l-.eJ")
Greer c. Tidwell ~ Date
EPA Regional Administrator
will
,'.
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RECORD OF DECISION
The Decision Summary
Sydney Mine Sludge Ponds Site
Hillsborough County, Florida
~
Prepared by:
U.S. Environmental Protection
Region IV .
Atlanta, Georgia
Agency
I
,
I
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1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
TABLE OF CONTENTS
Introduction. . . . . . . . . . . 0 . . . 0 0 . . 0 . . . 0 0 . . . . 0 0 0 0 0 0 0 . 0 0 0 . 0 0 . . . 1
1.1 Scope and Role of Final Operable Unit.................1
Site Name, Location, and Description......................1
Site History' .. d.................................... 0.....1
3.1 voluntary' Remedial Action.............................4
3.2 HRS/NPL Listing History'........................ . . . . . . .6
3.3 RI/FS History'......................................... 6
3.4 Enforcement Activities........................ . . . . . . . .7
Communi ty Relations.......... 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Summary of Site Characteristics..........._...............8
. I
5 0 1 pre-M~ning Geology.... 0 . . . . 0 . . . 0 . . 0 0 . 0 . 0 0 . . . . . . . . . . . . . 8
502 Mining History'................ 0 0 0 . . . . . 0 0 0 0 0 . . . 0 0 . . . . .10
5.3 Post-Mining Geology.................................. 14
5.4 Present Site Hydrogeology............................15
5.5 Ground Water: Surficial Aquifer Systems..............17
5 . 6 HaW'thorn Formation.. 0 . . . 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
5. 7 Floridan Aquifer... . . . . . . 0 . . . . . . . . . . . . 0 . . . . . . . 0 0 . . . . .18
5 0 8 Surface Wa tar. . . 0 0 . . . . . . . 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Summary' of Site Risks............... 0 . . . . . . . . . . . . . . . . . . . .19
6.1 Identification of the Contaminants of Concern........19
6.2 Exposure Assessment Summary...................~......19
6.3 Summary of the Toxicity Assessment of the
Contaminants of Concern.............................. 22
6.4 Risk Characterization Summary........................24
Description of Alternatives............................. .25
7.1 Alternative 1 - No Action............................25
7.2 Alternative 2 - Continued Operation of the Existing
Ground-Water Recovery and
Treatment System..................... 25
7.3 Alternative 3 - Evaluation/Modification of the
Existing Ground-Water' Recovery and
Treatment System..................... 26
Summary of Comparative Analysis of Alternatives..........27
Se lected Remedy............................... . . . . . . . . . . . 31
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Record of Decision
The Decision Summary
Sydney Mine Sludge Ponds Site
Hillsborough County, Florida
1.0
Introduction
The Sydney Mine Sludge Ponds Site (Sydney) was proposed for inciusion
on the National Priorities List (NPL) in June 1986. Voluntary
remedial activities with State oversight have been conducted by the
Hillsborough County Department of Public Utilities at the site.
Ongoing remedial activities are presently being performed by other
responsible parties. On September 6, 1989, the Proposed Plan, which
outlines the remedial action alternatives and the preferred
alternative, was issued to the public.
1.1
Scope and Role of Final Operable Unit
The activities at the Sydney site will be treated as one final
operable unit for remediation of the ground water. A remedy for" the
ground water is being proposed in order to protect public health and
the environment by controlling potential migration of contaminated
ground water to the Hawthorn Formation. The Hawthorn Formation
serves as a local drinking water supply.
This Record of Decision (ROD) has been prepared to 'summarize the
remedial alternative selection process and. to present the selected
remedial alternative for the site.
2.0
Site Name, Location, and Description:
The Sydney Mine Sludge Ponds Site in Hillsborough County, Florida,
occupies 9.5 acres of a 1,700-acre former phosphate mining site. The
site was strip-mined for phosphate rock in the 1930s and 1950s.
(See Figures 2.1 and 2.2.) It is located 15 miles southeast of
downtown Tampa in the unincorporated community of Brandon.
3.0
Site History
From 1973 to 1982, the Hillsborough County Public Utilities
Department rented the Sydney site for dumping septic wastes, waste
automotive oils, grease trap wastes, and manufacturing cutting oils.
During this period, the property was owned by the American Cyanamid
Corporation.
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10.0
Statutory Determinations................................. 33
10.1 Protective of Human Health and the Environment......33
10.2 Attainment of the Applicable or Relevant and
Appropriate Requirements (ARARs)....................33
10.3 Cost-Effectiveness............... ........... ....... .34
10.4 Utilization of Permanent Solutions and Alternative
Treatment Technologies to the Maximum Extent
Practicable. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34
10.5 Preference for Treatment as a principal Element.....35
LIST OF FIGURES
Figure 2.1. - Site Vicinity
Map. . . . . . . . . . . . . . . . . . . . . . . 0 . . . . . . . . . . 2
Figure 2.2 - Sydney Mine
Site Map.............'....... 0 . . 0 . . . . . . . 3
Figure 5.1 - Generalized Hydrogeologic Stratigraphic Column.....9
Figure 5.2
Schematic
Mining History............. 0 . 0 . . . . '0 . . . . . 11
Figure 5.3 - Mined and Unmined Areas of Sydney Mine............12
Figure 5.4 - Hydrogeologic Cross Section.......................16
Figure 6.1 - Total Residual VOC Content of Ground Water
in Oil Pond Sands................................. 20
Figure 6.2 - Total Residual VOC Content of Ground Water
in Spoil Row Material. . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
LIST OF TABLES
Table 6.1
- Oral Toxicity Values for the Contaminants of
Concern. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 . . . . 23
Table 8.1
- Glossary of Evaluation Criteria...................28
- Ground Water Remediation Goals....................32
Table 9.2
LIST OF APPENDICES
Appendix A - Site Data
Appendix B - Responsiveness Summary
Appendix C - State Concurrence Memorandum
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Mine Waste Cis 05al Site-Vicinit
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~. . . . .' Mine Property
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Taken from: Seabum and Rober1son, Inc.
CH2 M Hill ReOOI't Map Adapted by 8ooz. Allen & Hamilton Inc.
Figure 2.1
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SITE MAP-SYDNEY MINE WASTE DISPOSAL SITE 1CJ-i2J'A.
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In 1981, the property was purchased by the current owner, Waste
Management, Inc. During the eight-year span of waste disposal
operatio~s, an estimated 16 million gallons of wastes were deposited
in three small pits. (See Figure 2.2). These wastes were
transported to the site by various haulers serving homes, schools,
hospitals, and manufacturing and commercial establishments in the
Tampa Bay region.
In 1978, the Sydney sludge and oil pits became the focus of community
attention when the County considered using other phosphate mining
property for a solid waste landfill, a proposal the County later
rejected. The Florida Department of Environmental Regulation (FDER)
granted a construction permit for the existing waste disposal
activities in 1979, and an operating permit the following year. Also
in 1979, FDER and EPA included the site in their inventories of
potential hazardous waste sites in Florida.
As a result of the site's inclusion in these inventories, EPA's Air
and Hazardous Materials Division conducted a surface water and
ground-water investigation of the site during October and November
1979. The sampling program carried out at that time determined that
potable wells in the vicinity did not contain organic compounds or
heavy metals above background levels. However, mon~toring wells near
the sludge and oil pits contained both types of con~aminants at
elevated levels. In addition, EPA collected sediment samples from
Turkey Creek which flows through the former phosphate mine about
one-half mile east of the former waste disposal pits. Subsequent to
these findings, FDER began monitoring the site.
In late 1980, the Hillsborough'County Division of Public Utilities
notified EPA of hazardous waste activity at the site in accordance
with the Resource Conservation and Recovery Act (RCRA) notification
requirements. In 1981, EPA further investigated and evaluated site
conditions in response to local citizens' inquiries about. air and
water quality, and human health effects. In September 1981, FDER
denied issuance of a second operation permit. During that same
month, the site was closed to disposal activities.
3.1
Voluntary Remedial Action
In 1982, Hillsborough County officials, consulting with FDER,
investigated plans to remove contamination and restore the property.
The County contracted an environmental consulting firm, CH2M Hill, to
study the site and evaluate closure and restoration options. CH2M
Hill drilled a series of test wells and conducted a sampling and
analysis program to determine the types, location, and concentrations
of contaminants.
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Using this data, CH2M Hill evaluated several technologies for
treating the wastes including ground-water treatment, chemical,
physical, and biological treatment, thermal destruction, and on-site
. containment and disposal. CH2M Hill reported its findings to the
County in 1983. Of the options considered, the County selected
ground-water extraction and treatment, with excavation and on-site
incineration of the pit contents, as the most appropriate method to
remedy site contamination. '
Also in 1983, the County applied to FDER to approve a ground-water
monitoring plan to meet new State ground-water regulations, and CH2M
Hill examined the potential for performing the cleanup under the
Federal EPA Superfund program. The County continued activity under
State guidance.
In 1984, the County and State proceeded with the application process
and the commencement of the cleanup activities. In what later became
a two-phased effort, the activities in this first phase (Phase I)
included:
- Construction of a slurry wall to contain the waste pit
contents
I .
- "Excavation and on-site incineration;of approximately 10,900
cubic yards of disposal pond wastes in a mobile incinerator
.
- Pumping over 40 million gallons of contaminated ground water
in the vicinity of the pits and treating it in an air-stripping
tower on the site. The air-stripper uses a forced air and
water process to remove the contaminants from the water which
is then spray irrigated on land adjacent to the waste disposal
site.
Installation of the slurry wall and ground-water extraction wells was
completed by the end of 1984. Excavation and incineration of the
waste pit materials began in February 1985 and continued through
1986. During this period, cleanup contractors uncovered additional
contaminants buried adjacent to one of the pits. While studying the
site for other areas of contamination, contractors found several
spots adjacent to the pits and evaluated options for addressing the
additional contamination. "
As a result of the studies, in the spring of 1986, the County
selected excavation and on-site land treatment (air-drying) and
off-site disposal of residuals at an approved solid waste landfill.
This action was conducted in a second phase (Phase II) of the site
cleanup.
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CH2M Hill .initiated the actual Phase II site work in January 1987 and
completed it in August 1987. During this phase, approximately 15,000
cubic yards of contaminated materials were excavated from the site
and moved to the air-drying area. All materials treated by this
method were removed by August 25, 1987.
In summary, during the first four years of the site cleanup,
approximately 25,000 cubic yards of contaminated soils were
excavated, treated, and removed from the site. The ground-water
extraction and treatment operation is continuing with ground water
being pumped from 71 wells (.40 slurry wall wells, 13 North Dike
wells, 6 spoil row wells, and 12 oil pond recovery wells)~ Over 100
million gallons of contaminated ground water have been extracted and
treated since the operation began.
3.2
HRS/NPL Listing History
In 1982, EPA evaluated information on the site using the Hazard
Ranking System (HRS). Volatile organic compounds including toluene,
benzene, methylene chloride, 1,1-dichloroethane, and
trans-1,2-dichloroethane were detected at elevated levels. Theneed
to protect ground water qualified the site for the National
Priorities List (NPL) although it was not added to the list at that
time.
..
In 1985, EPA reactivated the Superfund HRS at the Sydney site in
response to Congressional concern about a number of sites that had
scored high enough, but were not added to the NPL. EPA's updated HRS
site investigation showed contaminants at elevated levels in an upper
or "perched" water table that had been created beneath the former
pits during phosphate mining activities. The perched water table
does not currently serve as a drinking water supply. Following this
investigation, EPA proposed the site for the NPL in June 1986.
County and State officials objected to EPA's action stating that EPA
failed to account for the significant cleanup effort already
undertaken by the Hillsborough County Department of Solid Waste and
its contractors. However, EPA's policy 'has always been that
voluntary hazardous waste mitigation activities do not preclude the
agency's listing the site. Since the Sydney site 'was proposed for
the NPL, the County, FDER, and EPA have continued coordination on
actions necessary to satisfy provisions of CERCLA.
""
3.3
RI/FS History
In 1988 and 1989, EPA reviewed the studies and actions previously
conducted at the site. The purpose of the review was to determine if
the accumulated information satisfied the requirements of a Remedial
Investigation/Feasibility Study (RI/FS) as stipulated under the
National Contingency Plan. .
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-7-
EPA also conducted a search to identify potentially responsible
parties (PRPs), that is, persons or companies who owned, used, or
transported wastes to the site and. therefore may have contributed to
the contamination problem. .
EPA's 1988-1989 review identified the need for an expansion of the
subsurface investigation to define more clearly the extent of
ground-water contamination. It also demonstrated the need to install
at least two more ground-water monitoring wells in order to check for
potential migration of contaminants from beneath the north pond, one
of the former waste pits. EPA also required a risk or endangerment
assessment (EA) whi~h analyzes the potential threat to human health
and the environment if no action were taken to a~dress the
contamination at the site. However, since actions have already been
taken at the Sydney site, the potential threat to human health and
the environment would occur if the present actions were discontinued.
Additionally, risk assessments evaluate the degree of harmfulness
(toxicity) of whatever contaminants are present. They also
characterize the kind of risks that might exist for human or other
environmental communities if exposed to contaminants. Exposure
pathways (for example, contact with air, water, or direct contact
with the waste) also are identified in risk assessments.
EPA has determined that the additional field sampling data generated
by Hillsborough County completes an evaluation and remedy selection
process which constitutes the Superfund Remedial
Investigation/Feasibility Study (RI/FS). This approach is consistent
with current policy concerning remedy selection for ground-water pump
and treat systems. EPA used the additional EA, analytical data, and
system performance data available to date to decide on further
actions needed at the site as described in this ROD.
3.4
Enforcement Activities
As recommended, Hillsborough County has added additional monitoring
wells and has prepared an EA based on sampling data gathered through
the spring of 1989. The County has succeeded in significantly
reducing the level of volatile'organic compounds in ground water on
the site. As a result of Hillsborough County's additional work, EPA
determined that the RI/FS process requirements were met.
On May 31, 1989, Hillsborough County ceased operating and maintaining
the existing ground-water recovery and treatment system and turned
the system over. to EPA. Operation and maintenance of the system was
turned over to other PRPs that were ordered by EPA to continue the
operation and maintenance begun by the County. These PRPs are also
continuing with the ground-water monitoring program established by
the County.
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4.0
community Relations
This Record of Decision presents the selected remedial action for the
contaminated ground water at the Sydney site in Hillsborough County,
Florida, chosen in accordance with CERCLA, as amended by SARA and, to
the extent practicable, the National Contingency Plan. Presentation
of the selected remedy to the public has been conducted in accordance
,with Section 117(a) of CERCLA to meet the public participation
responsibilities.
The Proposed Plan was released to the public on September 6, 1989.
This document was made public in both the administrative recor~ and
the information repositories maintained at the EPA Records Cente~ in
Atlanta, Georgia, and at the Brandon Public Library in Brandon,
Florida. The notice of availability for these two documents was
published in the Tampa Tribune on September 8, 1989. A press release
was issued to the media on September 11, 1989. A public comment
period was held from September 8, 1989 through September 29,1989.
In addition, a public meeting was held on September 13, 1989. At
this meeting, representatives from EPA answered questions about the
site and the remedial alternatives under consideration. A response
to the comments received during this period is included in the
Responsiveness Summary, which is part of this Record of Decision.
"
5.0
5.1
Summary of Site Characteristics
Pre-Mining Geology
The original topography of the area pas been severely disrupted by
phosphate mining. However, a number of investigations had been
conducted on the surficial geology prior to mining. A blanket of
surficial sands covered most of the area prior to mining. These
Pleistocene sands occurred throughout the area except along the
stream channels and within the associated floodplains. The maximum
thickness of the sand at the Sydney site was approximately thirty
(30) feet on the topographically high areas wit bin the mine site.
This surficial unit was generally composed of loose sands with some
cemented hardpan zones. The water table aquifer prior to mining was
contained within this unit. (See Figure 5.1.)
Underlying the surficial sand blanket is the Bone Valley Formation.
This unit occurred throughout the Sydney site, except along Turkey
Creek where the unit has been removed by stream erosion. The maximum
thickness of the Bone Valley Formation at Sydney Mine was estimated
at thirty (30) feet. In general, the Bone Valley Formation is divided
into upper and lower units. The upper unit was generally a
non-phosphatic sandy clay that was removed during the mining
operation. The lower unit, termed the "matrix" by the phosphate
industry, was composed of clays and sands which were rich in
phosphate ore.
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GENERALIZED HYDROGEOLOGIC STRATIGRAPHIC COLUMN
FOR WEST-CENTRAL FLORIDA
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. :~ V~N. P~R,K LIMESTON-E---t u:
. .
OCALA GRQUP
.
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-
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-
---- -
, . .
~ .
-
~:
11
-800'
/
STONE UNIT
/ I
/
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P.E. uMoreauz &. Assoaate5. tnc:.
'i:."~~: I~.'il':.",'j~; :",:, 1~
-',-
-------
-10-
.The phosphate ore present in this zone ranged in size from fine sand
grains to pebbles as large as three-quarters of an inch in diameter.
In many areas, the base of the Bone Valley Formation was marked by
the occurrence of coarse phosphate pebbles.
The Hawthorn Formation underlies the Bone Valley Formation throughout
the area and is exposed at land surface along Turkey Creek and in
many of the deeper drainage ditches on the property. In some areas,
the upper part of the formation was disturbed during mining
operations.
The Hawthorn Formation is composed primarily of clays and sandy clays
that range in color from blue-green to very light gray to white.
Phosphate grains occur randomly throughout the section with fairly
high concentrations in some zones. Some of the white, calcareous
clays and sandy clays are the products of limestone weathering.
Limestone lenses and thin layers occur in the lower section of the
unit. The limestone lenses are generally cream to tan and sandy
containing varying amounts of clay. Some zones are very
fossiliferous. Preliminary data indicate that the amount of
limestone in the Hawthorn increases to the east.
I
I .
--
-'
'"
5.2
Mining History
Phosphate mining has occurred during two periods at the Sydney site.
Mining first took place during the 1930s but ceased prior to 1940.
(See Figures 5.2 and 5.3.') American Cyanamid Corporation resumed
mining at the site in the 1950s. The north clay settling pond
generally outlines the extent of the early mining activity. "
Intensive mining occurred south of State Road 60 to approximately 700
feet north of the east-west retention dike which separates the north
and south ponds and abuts the northern end of the Sydney site.
Mining cuts in this north pond area were generally in an east-west
direction.
0-
-"
~
Other areas were excavated but not completely disrupted. A ditch has
been identified from early aerial photographs that ran west to east
beneath the Sydney site. It extended eastward to the limits of the
south slimes pond and then turned northward inside the eastern
retention dike of the north pond. This deep trench may have been
used initially to dewater the phosphate matrix and later as a process
water circulation ditch.
There appears to have been limited mining activity in the area
immediately northwest of the Sydney site. The topographic low in
this area was used as a part of the water circulation system.
-------
.--.------------ -'"
A
PRE-MINING
COI'ln/lIONS
. . 811 . III II . IC III ,. N" III III III I( . III -1iII~-" III
. . . . . . .' O. V.E A. 0" U.A O. r: "I- . . . . . . . .
.. .. .. .. III .. .. L:.- III l1li .. .. .. . .. ..
.. .. II .. .. .. .. .. iii 811 l1li ". III III lit. .. ..' III .. III. III ... II' .. l1li II II" .. "II" II" ..
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:.-:~..; - ~:.. ..:.,~ MA fAlx ':,: ...;.,- :; ...-=-"",;- :-:~-,~~
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:.'.....". ;,'.:.OVEABUADEN /;-~~-- .. ....
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----
Schematic Minina
History (adar
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o
---
:
--
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KEY
r-:lovlIIOIIIIOtll, 'lfluocwt
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,..<)CiOlt 'IAWII,IJ'!"
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(::.~:~la\'Enua'IIU(". ""'fA 'UOCf"E
:.:::~- OL"": "...u i I 'U"",,,,"Ou
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r-:'~--l\4A fllla.luGI". '1'0"'14 lie,
?": 1 U>ilt.. l'lluCtUL )~IU:: '/AtltJ
~..;- , 0'1101'" lIufl
(illJ WASH Cl..
[7]8(0"." .q't
:::::::: 'l.ul ~..t Ca A r
bISA"O 'AILlllla
Figure
5.2
horn
Sea burn
and Robertson, 1978b)
"fCA26142.AO
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E
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,.
-12-
60
c
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o
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II
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DURANT ROAD
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o
DISTURBE::J DURING MINING
MINED, NUMBERS INDICATE
CA.:: MINED
POSSiBLY
MINED
o
~
-N-
~
Mined and unmined areas of Sydney
Seaburn and Robertson, 1978b)
mine
(modified
from
Figure
5.3
Pf~'Jncflf,p.' ?3Sl:
-------
-13-
After mini~g resumed in 1950, the.north pond (mined in the 1930s) was
- converted ~nto a clay waste settl~ng pond by constructing a perimeter
dike, about twenty (20) feet high, from overburden spoil material
remaining from the earlier mining. In some areas inside the dike,
excavations were deepened to supply additional material for dike
construction.
The south settling pond was mined early after American Cyanamid
Corporation resumed operations. Excavations extended through the
southern dike of ,the north pond and approximately 300 feet north into
the area mined in the 1930s. The disposal pits were located above
the twice mined/disturbed area. It appears, from aerial photographs,
that the extreme northwestern corner of the south pond was-not
completely mined. The direction of mining cuts was predominantly
north-south in this area. Following completion of mining operations
in the southern area, the existing dike was constructed surrounding
the north and south ponds. This retention dike, approxLmately forty
(40) feet high, was composed of overburden disturbed during mining
and some consolidated waste clays from the north pond. The re-mining
and the construction of this dike disrupted the slime overlapping the
inside dike face relationship that existed along the southern
boundary of the northern -settling pond. AIQng undisturbed dikes,
clay slimes overlapped part of the inside dike. The slimes layer
began at approximately the elevation of the old water level and
, thickened toward the dike base and the center of the pond.
After use as a settling pond for a number of years, during which a
thick layer of phosphate slime was deposited, sand tailings were
pumped across the surface of both the north and south ponds. These
tailings were thickest near the discharge point and in the areas
underlain by overburden mounds. The sands thinned near the centers
of the ponds and in areas where dense vegetation emerged.
In the southern part of the north pond, a large area was filled with
sand tailings to the same elevation as the higher retention dike.
This area of smooth, well-graded sand was constructed to provide a
road for a dragline to cross Turkey Creek. During construction of
the dragline crossing, the 20-foot high dikes on the eastern and
western sides of the north pond appear to have been disrupted where
they intersect the 40-foot high dike separating the north and south
ponds. .
Additional sand tailings were discharged into both north and south
settling ponds following construction of the dragline path. An
east-west aligned ditch was then excavated through the sand cap and
was used to move clay wastes to holding ponds east of Turkey Creek.
The clay slurry was pumped from the plant near the existing target
range to the ditch, which began Lmmediately north of the oil and
grease disposal pond, where it flowed downgradient to the east and
through a pipeline crossing Turkey Creek.
-------
-14-
5.3
post-Mining Geology
Surficial geology in the Sydney site area has been severely disrupted
by phosphate mining activities. The water table in the immediate
area of the disposal site is perched, and resides a man-made aquifer
composed of sand tailings. Contaminant percolation from the disposal
ponds is predominantly lateral in the sand tailings due to the
extremely low permeability of the underlying slimes.
The Pleistocene sands, all or part of the Bone Va~ley Formation, ,and
some of the upper Hawthorn Formation clays were excavated by
draglines. Phosphate ore was pumped t9 the processing plant in a
slurry where the phosphate was separated from the waste matarial.
Two types of waste material were generated during the separation
process: sand tailings, the coarse sand fraction; and slimes,
composed primarily of clays and silt size quartz and phosphate
particles. Once separated, the phosphate slimes were pumped to
settling ponds constructed in mined areas, or in some instances, on
undisturbed ground. The sand tailings were pumped into some of the
ponds after they were filled with waste clays.
All overburden material above the Bone Valley phosphate ore zone was
removed and placed into linear piles that paralleled the mining
cuts. Much of the overburden remained in the clay settling ponds
with the remainder used to construct the existing pond retention
dikes. '
The retention dikes were constructed, from a wide range of material,
but were primarily overburden sands and sandy clays without uniform
arrangement. The overall permeability of the material in the
retention dikes was fairly high. West of the Sydney site, the dike
was found to contain phosphate slime in the upper sections which
retards downward filtration. .
'.
Hardpan layers occurred within the retention dike north and west of
the Sydney site. These hardened sand layers were semi-cemented by
iron oxide and/or calcium carbonate that precipitated from ground
water generally in the zone of water table fluctuation. North of the
site, the hardpan occurred at 18 to 20 feet below land surface
(BLS). The dike section west of the site was found to contain a
hardpan layer at a depth of 15 to 16 feet BLS.
The overburden mounds in the south pond generally ran north-south.
These lirtear features were spaced approximately 150 to 250 feet apart
and were composed of material similar to that occurring in the
retention dikes. The septic waste disposal pit was located
immediately above the small northwest trending overburden mound and
on the northern flank of another. A third mound occurred beneath the
eastern section of the pit. The oil and grease disposal pit was
constructed above the north end of one of the overburden mounds.
-------
-15-
The waste clay slurry was pumped into a holding pond where the clays
slowly settled to the bottom and consolidated over a period of many
years. The clay layer was thicker in the troughs between overburden
piles and in the trough that generally occurred at the base of the
retention dikes. The clays were thinner where they covered the lower
overburden mounds and along the slopes of the retention dikes where
it was estimated to be less than five (5) feet thick.
Mining operations at the Sydney site have altered the configuration
of the local subsurface. Several geologic horizons were , exposed in
the mining pits as a variety of factors influenced the depth to which
the draglines excavated. Ditches were excavated ~round mining cuts
to facilitate matrix dewatering and to provide mate~ial for dam
construction. This resulted in trenches throughout the site which
were excavated into the top of limestone and were deeper than the
mining cuts.
Since phosphate ore concentrations varied, some areas were excavated
to the top of the limestone and others were never mined. The end
result produced a topographic surface in which the upper Bone Valley,
lower Bone Valley, and the Hawthorn Formation were exposed.
5.4
Present Site Hydrogeology
The hydrogeologic framework of the Sydney site is quite complicated.
(Figure 5.4.) The original soils at the site have been reworked into
a series of man-made aquifers and confining units. The uppermost
unit is comprised of sand tailings derived from the ore preparation
process. These sands qre relativelY3permeable having an estimated
horizontal permeability of 1.0 x 10- centimeters per
second (em/see). Wells installed into this unit readily recover
contaminants using vacuum pumping. The sand tailings comprise the
unit in which the oil pond wastes and septic pond wastes were
disposed. During the rainy season, the water table in the sand
tailings rises causing contaminated ground water to flow northward
and down onto the north dike silty sands.
These sand tailings rest on partially consolidated, very low
permeability, phosphatic clay wastes (slimes). Direct downward
movement of the oil pond wastes and the septic pond wastes is
retarded by these clays. The sand tailings north of the north dike
contain a separate water table from those of the tailing sands
located south of the dike. Where contaminated ground water flows
downward from the sand tailings located south of the dike, the silty
sands of the north dike are contaminated.
-------
, .
100
I
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t- 90
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m ~ m
~~ i i~
.... .. ..... "0""""""""" ................
'.:-:.:-:::::: :::::-::::::::::::::::::::::::::' .-::::::::::::: ::::) A!qt-!G~::::::::: :::::::::::::::::::::::::::::::::: '- ::-7..::.:::.:::..:::,:::.:::..~.'.:,:::,"','
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PHOSPHATIC
III filii I1I11 11111 II
Cl~.rIlY{f},~,U:S
(SLIMES)
, ,
. .
30
. .INTERVAL ---
: : : :' . .;. MONITORED
::~ U [ ~ li U i ~ U j ! ~ i j j-~~~f:~~I~~~ \:~
]
20
10
SEA
U:W.L
-10
.20
.--'
0'
--r .-- -.- ---,---'
:WO' :500'
HOHllOI'ITAI. SCAI.E
I
500'
[ht\f\~ttill
INDICA TES APPROXIMA 1E
POSITION OF CaNT AMIIM nON
OCTOBER 1988
I
100'
1
400'
Nol~
i'6f~ 'j'lt": Of CIWSS SEC liON
~)n I u;UH£ J."
FIGURE 5. 4
Hydrogeologic Cross Section; Sydney Mine Waste Di~posol Site
-
-
~
-
-------
-17-
These silty sands comprising the dike were obtained from the spoil
rows (long, parallel rows trending north-south at locations south of
the north dik~ and east-wes~ at locations to the north of the north
dike.) The silty sands were determinei to have an average
permeability (five wells) of 6.0 x 10- em/sec. Ground-water
recovery wells in the silty. sands of the north dike and the spoil
rows is slow; such wells are capable of producing only 0.25 to 3
gpm. Accordingly, horizontal movement of ground-water contaminants
in the spoil row silty sand material is very slow.
Underlying the spoil row sands are very low permeability clays of the
unmined zone. These clays, belonging to the uppermost part of the
Bone Valley Formation, represent the base of mining operations. The
clays appear to have been breached locally by mining operations.
This has alldwed the downward migration of contaminants into sand
stringers or layers of more permeable phosphatic sands within the
Bone Valley unit. The Bone Valley rests on top of clays comprising
the upper portion of the Hawthorn Formation. Underlying this clayey
zone are found the limestones (dolomite) of the Hawthorn Formation.
5.5
Ground Water: Surficial Aquifer Systems
Water level measurements from monitor wells near the Sydney site hav~
identified two distinct surficial aquifer (water table) systems. .One
is a perched water table within the sand tailings that cover the
south clay settling pond. A second water table aquifer exists north
of the site. The latter occurs at a lower elevation than the perched
system and is areally more extensive and is perched on either
formational clay or by clay slimes above formational clay. This
local water table aquifer is hydraulically connected to the surface
water systems by drainage ditches located west of the site as well as
to Turkey Creek located one-half mile east of the site. The water
table is highest south of the site, within the topographically high
Isand tailings where it is perched on clay slimes and hardpan zones
'that. form part of the dike. .
The lower water table system extends from within the retention dike
north of the site into the north slimes pond and ranges in elevation
from 68 feet to about 71 feet above mean sea level. The Sydney site
is located in an area of recharge. Ground water moves from the upper
perched system across the northern dike structure and infiltrates
downward into the lower water table system. The primary directions
of perched ground-water movement are north, northwest, and east.
-------
-18-
5.6
Hawthorn Formation
The Hawthorn Formation at the Sydney site is characterized by varying
lithologies. Locally, limestones within the Hawthorn may constitute
aquifers; however, generally the Hawthorn is not an aquifer and
yields only minimal quantities of water to wells. The Hawthorn
underlies zones of contamination with considerable separation by
stiff to sticky clays. Sampling results indicate that thgse natural
clays have8a vertical permeability ranging from 3.5 x 10- to
7.28 x 10- cm/sec.
Test drilling data indicates that the uppermost portion of the.
Hawthorn is composed primarily of impermeable clays containing thin
lenses of limestone. This portion of the Hawthorn is interbedded
clay, sand, clayey sand, sandy clay, and impure sandy or clayey
limestone or dolomite, all containing varying amounts of phosphate
nodules. To the west, the Hawthorn is clayier with persistent but
thin limestone lenses. At the Sydney site, these layers occur in the
lower part of the formation and are generally one to two feet thick.
5.7
Floridan Aquifer
The Floridan aquifer is the principal artesian aquifer in central
Florida. It is comprised of the Tertiary carbonate rock units below
the Hawthorn Formation and is generally separated from the Hawthorn
Formation by confining clays within the Tampa Limestone, except in
localized areas where clay is absent. (See Figure 5.1.)
The water supply for domestic, public, and municipal purposes comes
primarily from the upper units of the Floridan. Domestic wells are
generally about 170 feet deep, public supply wells are 300 to 400
feet deep, and irrigation wells are 200 and 500 feet deep.
5.8
Surface Water
Much of the rain that falls on the Sydney site rapidly infiltrates
downward into the surficial sands replenishing the perched water
table and area water table systems. The remainder accumulates in the
drainage ditches on site and ultimately flows into Turkey Creek.
Turkey Creek is the primary drainage outlet for the site. It flows
southward along the eastern property boundary and discharges into the
Alafia River to the south.
Natural surface water runoff patterns have been drastically altered
by mining activities, further changed by the construction of the
disposal pits, and then modified by the remediation activities.
-------
-19-
South and west of the site, surface runoff is collected by a ditch
located south of the access road. Water in this ditch is conveyed to
a larger ditch which flows in an easterly direction. The latter also'
drains the western part of the site and ultimately discharges into
Turkey Creek. East of the site, surface runoff flows in an easterly
direction. During the rainy season, the perched ground water level
around the site rises forming ponds and sprin9s.
6.0
6.1
Summary of Site Risks
Identification of, the Contaminants of Concern
Indicator chemicals are selected on a site specific basis. The
compounds selected were those compounds which are the most toxic,
mobile, and presently persistent chemicals at tpe site. Volatile
organic compounds represent the principal contaminant group at the
site. These compounds were present in the sludges originally
analyzed in the waste ponds in 1983 and continue to be present at
lower levels in ground water adjacent to and north of the former
disposal ponds. Ground-water quality data of volatile and
semi-volatile organic contaminants are ~ummarized in Appendix A.
(See Figures 6.1 and 6.2.) Although the compositing technique is not
generally recommended, the risk levels that were quantified using
these exposure concentrations indicate that groundwater remediation
is required which is presently ongoing.
Surface water samples were collected by EPA from Turkey Creek (the
nearest named stream, located east of the former disposal area).
Analysis indicates that volatile organics were not detected in this
creek.
,
Where possible, semi-volatiles were considered in the risk
assessment. No metals, PCBs, or dioxins were considered to be
contaminants of concern, either because they were not detected, or
because of their paucity of detection relative to the volatile
organic chemicals.
6.2
Exposure Assessment Summary
A risk assessment for this site was developed using an exposure point
concentration estimation model. This approach is semi-quantitative
and is not a computer model. Exposures at the site were considered
for both potential current and potential future scenarios. The
pathways considered for potential current exposures were limited to
the following:
a. Air - inhalation of vapors released to the air from
subsurface soils or ground water. The receptors could be
on-site trespassers, children playing on the site, dirt bike
r iqers, and hunters..
-------
~-
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NOTES: \:\ !
rOTACvoC I~ESULTS \.\ I
~~~ :JL~ ~~~ES ~:'::K
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LABOHA TORY ".1('..,
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FORMER
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AREA
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(0)
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rJ r:P.c,
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LE!lEllil
& OaRING (I'LUGGED)
. MONI fOR WEll
. RECOVERY WEll
(100150 CONCENTRA nON CONIOURS
100 OF TOTAL VOC'5 (ppb)
IN SPOil ROW IAA TERIAl
200
I
JOO
1
@NUW-1
(0)
TREE
LINE
100
'.-
SCALE IN FEET
Total Residual VOC Conlent
of Groundwater in Spoil Row Malerial
January 4-5, 1989
Figure 6. '2
. ."IUfln\6or.
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NOTES: \:>\ !
TOTACVOC RESULTS I>' I
~~;~;~f~~;;;M~ ~... ill
LABOIMTORY "J(~
,>,">~
J( '\"~ .
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I XI R-x--, ~"- . -.. n '.._-- J
"':;~:~:';"I r ("~"IIII)~! ~~~~~:_:':"--
L)(_><-x-1 - ------ --=-~'~~:'~-~-='~:::""h':h"::'_-=::"-====--/
FORMER
OIL POND
AREA
o SRW-l0
(0)
e
SRW-8
(4.9)
,-
,
I
,
\
,
'-
J
zr
I
N
......
I
LE!lfllil
& BORING (I'LUGGED)
(I MONI roR WEll
o RECOVERY WELL
(100150 COUCENTRAnON CONrDUR5
100 Of TOTAL VOC'S (ppb)
IN SPOIL ROW MA T£RIAL
Figure 6.2
200
I
300
,
o NLtW-J (0)
(!)NMW-1
(0)
TREE
LINE
100 0
11....:....1
100
'--
SCALE IN FEET
Total Residual VOC Content
of Groundwater in Spoil Row Material
January 4-5. 1989
I ........-
-
-
~gjJJ.J
~
-------
-22-
b. Wildlife - ingestion ~f
birds or animals living
evidence to suggest the
contaminants bioaccumulated in game
on or near the site (there is no
presence of contaminated game).
The pathways considered for potential future exposures included the
following: .
a. Residential - inhalation of vapors released from subsurface
soils or ground water; inhalation of VOCs released during
household use of ground water; direct contact with'
contaminated ground water during household use; and
ingestion of contaminated-ground water. The receptors
considered were both on-site and downgradient, off-site
residents.
b. Industrial - inhalation of contaminated particulates and/or
vapors .released from soils and ground water; direct contact
with and/or incidental ingestion of contaminants; and
ingestion of contaminated ground water. Receptors include
on-site workers.
c. Recreational - inhalation
ingestion of contaminants
on or near the site. The
visitors to a future park
may consume game presumed
of vapors released from soils; and
bioaccumulated in wildlife living
receptors are considered to be
and hunters and their families who
to be contaminated.
Only ground-water exposures were quantified in the potential future
site condition and use setting evaluation. Other exposures were
considered qualitatively relative to their impact on the overall
assessment of risk.
6.3
Summary of the Toxicity Assessment of the Contaminants of
Concern
Cancer potency factors (CPFS) have been developed by EPA's
Carcinogenic Assessment Group for estimating excess lifetime cancer
risks associated with exposure to potentially carcinogenic 1
chemicals. CPFs, which are expressed in units of (mg/kg-day)- ,
are multiplied by the estimated intake of a potential carcinogen, in
mg/kg-day, to provide an upper-bound estimate of the excess lifetime
cancer risk associated with exposure at that intake level.
The term "upper bound" reflects the conservative estimate of the risk
calculated from the CPF. Use of this approach makes underestimation
of the actual cancer risk highly unlikely. Cancer potency factors
are derived from the results of human epidemiological studies or
chronic animal bioassays to which animal-to-human extrapolation and
uncertainty factors have been applied.
-------
-23-
Reference doses (RfDs) have been developed by EPA for indicating the
potential for adverse health effects from exposure to chemicals
exhibiting noncarcinogenic effects. RfDs, which are expressed in
units of .mg/kg-day, ar~ estLmates of lifetLme daily exposure levels
for humans, including sensitive individuals. EstLmated intakes of
chemicals from environmental media (e.g., the amount of a chemical
ingested from contaminated drinking water) can be compared to the
RfD. RfDs are derived from human epidemiological studies or anLmal
studies to which uncertainty factors have been applied (e.g., to
account for the use of anLmal data to predict effects on humans.)
These qncertainty factors help ensure that the RfDs will not
underestLmate the potential for adverse noncarcinogenic effects to
occur.' .
Not all compounds have an established RfD for either the ingestion or
inhalation route, or both. Therefore, where an RfD was not
available, the exposure to that compound was not quantitatively
evaluated. Only RfDs published to date in the Integrated Risk
Information System (IRIS) database were considered for use in the
risk assessment. The following Table 6.1 contains the cancer potency
factors and references doses for the contaminants of con~ern.
Table 6.1
Oral Toxicitv Values for the Contaminants of Concern
ComDound
1, 1, l-Trichloroethane
l,l-Dichloroethane
1,2-Dichloroethane
l,l-Dichloroethene
Benzene
Chlorobenzene
Ethyl Benzene
Toluene
Vinyl Chloride
Reference Dose
(ma/ka-dav)
9 x 10-f
1 x 10-
NA
9 x 10-3
NA
2 x 10-f
1 x 10-1
3 x 10-
NA
Potency Facror
(ma/ka-daY=-l
NA2
9.1 x 10- 2
9.1 x l~-
6.0 x 10- 2
2.9 x 10-
NA
NA
NA
2.3 x 100
NA = Agency verified toxicity values are not available.
-------
-24-
6.4
Risk Characterization Summary
Excess lifetLme cancer risks are determined by multiplying the intake
level with the cancer potency factor. These risks are prObabil~ties
that are generally expressed in scientisic notation (e.g. 1x10- ).
An excess lifetime cancer risk of 1x10- indicates that, as a
plausible upper bound, an individual has a one in one million chance
of developing cancer as a result of site-related exposure to a
carcinogen over a 70-year lifetLme, under the specific exposure
conditions at a site. '
Potential concern for noncarcinogenic effects of a single contaminant
in a s~ngle medium is expressed as the hazard quotient which is the
ratio of the estLmated intake derived from the contaminant
concentration in a given medium to the contaminant's reference dose.
If the hazard quotient (HQ) exceed's unity, this is an indication
that the exposure levels are greater than the RfD and there is a
potential for noncancer health effects. By adding the HQs for all
contaminants within a medium or across all media to which a given
population may reasonably be exposed, the Hazard Index (HI) can be
generated. The HI provides a useful reference point for gauging the
potential significance of multiple contaminant exposures within a
single medium or across media.
The risk assessment indicates that' there may be a potential for
adverse human health effects to on-site residents due to the
ingestion of compounds classified as carcinogenic. Based on a
potential future, on-site, residential use scenario, the est~ated
lifetime cancer risks were generally greater than the 1 x 10-
acceptable range.
-
.. "I....
......,
For the future, potential, off-site, ground-water use scenarios which
assumed off-site migration of ground-water contamination and
subsequent ground-water ingestion, the estLmated excess lifetLme
cancer risks generally fall within the acceptable risk range
identified by EPA. Predictions of off-site migration tendencies were
made using models, employing specific assumptions regarding estimates
of exposure point concentrations which contained inherent
uncertainties. The noncarcinogenic daily intake compared to RfDs
showed no exceedances of the RfDs, and the hazard indices did not
exceed one in any case examined.
Releases or threatened releases of hazardous substances from this
site, if not addressed by Lmplementing the response action in this
ROD, may present an unacceptable risk to public health, welfare, or
the environment. .
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-25-
7.0
Description of Alternative~
Three alternatives were considered for remediation of the ground
water at the Sydney site. The following remedial alternatives which
were considered are discussed in the next sections:
- Alternative 1 - No Action
- Alternative 2 - Continued Operation of the Existing Ground-
Water Recovery and Treatment System
Alternative 3 Evaluation/Modification of the Existing
Ground-Water Recovery and Treatment System
7.1
Alternative 1 - No Action
The Superfund program requires that the no action alternative be
considered at every site. Under the no action alternative, EPA would
.take no action at the site to control the source of contamination.
The no'action alternative serves as.a baseline with which other
alternatives can be compared. Potential human health risks
associated with current exposure paths would remain on site. This
alternative exceeds the target risk range and does not attain ARARs.
The no action alternative proposes leaving the site in its present
condition and stopping the ground-water recovery and treatment
system. Quarterly ground-water monitoring would continue for a
period of five (5) years. A review would be' performed every five (5) .
years as long as contaminants remain above health-based levels to
. evaluate potential changes in risk associated with no action.
The present (1989) worth cost of this alternative includes only
ground-water monitoring for five years (20 quarters), and is
estimated at $12,000 per quarter for a total of $240,000.
Alternative 2 - Continued Operation of the Existing
Ground-Water Recovery and Treatment System
The existing recovery and treatment system was installed in late
1984. The recovery system pumps ground water from a total of 71
wells (40 slurry wall wells, 13 North Dike wells, 6 spoil row wells,
and 12 oil pond recovery wells.) The treatment system consists of an
air stripper which uses a forced air and water process to remove the
contaminants from the water. The treated water is then sprayed over
a portion of the disposal site to facilitate flushing of the
aquifer. Between 400,000 and 1,000,000 gallons of water are being
recovered and treated each week.
7.2
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-26-
Ground-water use restrictions would be imposed on-site and within a
reasonable distance of the site during remediation and operation and
maintenance in keeping with the establishment of maximum levels of
ground-water contaminants. This alternative would serve as an
effective measure toward .preventing potential exposure by ingestion
of contaminated ground water.
A quarterly mon~toring program to analyze for those ground-water
constituents of concern would be implemented during the remedial
action. Following remedial action completion, a review would be
conducted by EPA every five (5) years should contamination remain
above health-based levels. After the first review, monitoring would
continue annually provided the review does not identify a need for
further remedial action or monitoring, or provided that health-based
levels have been attained throughout t~e aquifer systems.
The. present (1989) value cost for this alternative is estimated at
$1,392,000. This cost includes operation and maintenance of the
existing system for two years (8 quarters) at $144,000 per quarter
and ground-water monitoring for five years (20 quarters) at $12,000
per quarter. .
7.3
Alternative 3 - Evaluation/Modification of the Existing
Ground-Water Recovery and Treatment System
This alternative involves continued operation of the existing
recovery and treatment system as well as an evaluation of the en~ire
system to ~etermine its effectiveness and efficiency. A detaile~
analysis of the existing system would determine if there is a need
for installation of additional wells or if pumping of some of the
existing wells could be stopped. The analysis would also include
designing a schedule for temporarily shutting down the entire system
to evaluate remedial action success. This would allow the ground
water to recharge and reach equilibrium. Additional sampling and
analyses could then produce the necessary data to determine if
contaminant levels have indeed. reached the desired cleanup levels.
A quarterly monitoring program to analyze for those ground-water
constituents of concern would be implemented during the remedial{
action. A review would be conducted by EPA every five (5) years
following remedial action completion. After the first review,
monitoring would continue annually or semi-annually provided the
review does not identify a need for further remedial action or
monitoring. Attainment of remedial goals may be cause for ending
monitoring activities.
-------
-27-
Ground-water use restrictions would be imposed on-site and within a ,
reasonable distance of the site' during remediation and operation and
maintenance in keeping with the establishment of maximum levels of
ground-water contaminants. This alternative would serve as an
effective measur~ during implementation of the remedial action toward
preventing potential exposure by ingestion of contaminated ground
water.
The present (1989) value cost for this alternative is estimated at
$2,448,000. This approximate cost includes: design modifications and
construction at $480,000; operation and maintenance of the system for
three years (12 quarters) at $144,000 per quarter; and ground-water
monitoring for five years (20 quarters) at $12,000 per quarter.
8.0
Summary of Comparative ~alysis of Alternatives
This section provides the basis for determining which alternative
provides the best balance of trade-offs with respect to the
evaluation criteria. The major objective of the Proposed Plan was to
outline and evaluate alternatives for remediating the Sydney site.
Several remedial technologies were identified for the ground-water
cleanup. These technologies were screened based on their
feasibility, given the contaminants present and,site characteristics.
Three alternatives have undergone a detailed evaluation and were
listed in the previous section. The alternatives were evaluated in
detail based on the nine evaluation criteria required by SARA.
A glossary of these evaluation criteria is offered in Table 8.1.
Following the glossary is the summary of the alternatives' relative
performance with respect to each of the nine criteria.
I .
-------
-28-
Table 8.1
Glossarv of Evaluation Criteria
Overall Protection of Human Health and the Environment - addresses
whether or not a remedy provides adequate protection and describes
how risks posed through each pathway are eliminated, reduced, or
controlled through treatment, engineering controls, or institutional
controls.
Compliance with ARARs - addresses whether or not a remedy will
all of the applicable or relevant and appropriate requirements
other Federal and State environmental statutes and/or provides
.grounds for invoking a waiver.
meet
of
Lonq-term Effectiveness and Permanence - refers to the magnitude of
residual risk and the ability of a remedy to maintain reliable
protection 'of human health and the environment over time once cleanup
goals have been met.
.
'.-
..,.~,
Reduction of Toxicity. Mobility. or Volume - is the anticipated
performance of the treatment technologies that may be employed in a
remedy.
Short-term Effectiveness - refers to the speed with which the remedy
achieves protection, as well as the remedy's potential to create
adverse impacts on human health and the environment that may result
during the construction and implementation period.
Implementability - is the technical an~ administrative feasibility of
a remedy, including the availability of materials and services needed
to implement the chosen solution.
Cost - includes capital, operation and maintenance costs, and
ground-water monitoring.
State Acceptance - indicates whether the State concurs with, opposes,
or has no comment on the preferred alternative.
Community Acceptance - will be assessed in the Responsiveness Summary
in the appendix of the Record of Decision after reviewing the public
comments received on the Proposed Plan.
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-29-
summary of Comoarative Analvsis of the Alternatives
Overall Protection of Human Health and the Environment
All of the alternatives, with the exception of the no action
alternative, would provide adequate protection of human health
and the environment by elLminating, reducing, or controlling
risk through treatment, engineering controls, or institutional
controls. The preferred alternative would continue the
treatment of the contaminants in the ground water, thereby
reducing risk associated with direct contact and minLmizing
potential migration.
Although the no action alternative includes past voluntary
cleanup actions, it is not completely protective of human
health and the environment. Therefore, it is not considered
further in this analysis as an option for the site. The
analysis will now only refer to Alternatives 2 and 3.
Compliance with Aoolicable or Relevant and Aoorooriate Reauirements
Both alternatives would meet respective applicable or relevant
and appropriate requirements (ARARs) of Federal and State
environmental laws. Maximum Contaminant Levels (HCLs)
promulgated under the Safe Drinking Water Act (SDWA) and State
of Florida ARARs, where they are more stringent, will generally
be the relevant and appropriate standard for ground water that
is or may be used for drinking water. There are some
situations when an aquifer that is a current or potential
drinking water source cannot be remediated to ARARs. If the
ARARs cannot be attained (e.g. because of complex hydrogeology
or other environmental conditions), an ARAR waiver for
technical impracticability may be used. Table 9.1 lists the
ground-water remediation goals for the Sydney site.
Lona-term Effectiveness and Permanence
Ground-water recovery and treatment would produce a permanent
remedy. Long-term permanence and effectiveness may be. provided
by both Alternatives 2 and 3; however, only Alternative 3 can
provide better long-term effectiveness and permanence by
completing a detailed analysis of the existing system and
providing appropriate system modification.
-------
1-
-30-
This alternative would also include making modifications, if
necessary, to the system and thus improve the effectiveness and
efficiency. This might also decrease the length of time needed
'to complete the remediation.
Reduction of Toxicitv. Mobilitv. or Volume
Both Alternatives 2 and 3 would reduce the toxicity, mobility,
and volume of the ground-water contamination by decreasing the
size of the contaminant plume. Alternative 3 would assure
reduction of toxicity, mobility, and volume to the maximum
extent practicable.
Short-term Effectiveness
Alternatives 2 and 3 will require varying amounts of time to
achieve cleanup of the site. None will be Lmmediately
effective upon completion of modifications.
.' .d
Implementabilitv
The implementability of. an alternative is based on technical
feasibility, administrative feasibility, and the availability
of materials and services needed to implement a particular
option. Both alternatives are technically and administratively
feasible. Both alternatives involve technologies which have
been used in the past and have a demonstrated performance
record.
Cost
Both Alternatives 2 and 3 have costs associated with operation
and maintenance of ' the treatment system. For Alternative 3,
the additional cost includes the design and construction of
modifications to the treatment system. All alternative cost
estimates, including the no action alternative, contain
expenses for five years of ground-water monitoring.
State AcceDtance
The State of Florida as represented by the Florida Department
of Environmental Regulation is in favor of the selected remedy
for remediating the ground water at the Sydney site.
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-31-
Community Accectance
At the public meeting held on September 13, 1989, the community
was briefed on the selected remedy that will effectively
protect human health and the environment.
9.0
Selected Remedy
Based on available data and analysis to date, the U.S. EPA selects
Alternative 3 as the most appropriate solution for meeting the goals
of the ground-water remediation at the Sydney site. Based on current
information, this alternative provides the best balance among the
nine criteria that EPA uses to evaluate alternatives. Table 9.1
lists the ground-water remediation goals for the site.
This alternative would provide for an evaluation of the existing
ground-water recovery and treatment system currently operating at the
site, followed by modifications designed to improve the effectiveness
and efficiency of the, ground-water remediation. Ground-water
sampling and analysis will continue in order to provide a basis from
which to evaluate the" effectiveness of the system.
Also included in this alternative will be the evaluation of the need
for deed restrictions for areas of the site which may continue to be
impacted by ground-water contamination after the best available
remediation technology has been implemented. Deed restrictions will
protect future users of the water supply in the Lmmediate area of the
site. Timeliness of the remediation will be improved by modifying
the system as appropriate to achieve remediation goals.
The rationale for choosing this alternative includes the following
reasons:
allows for a more complete and expeditious remediation of the
ground water than the other alternatives;
contributes to the implementation of a permanent remedy at the
site;
reduces the potential for contaminant plume migration.
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-32-
Table 9.1
Ground Water Remediation Goals
Contaminant
Remediation
Goal lua/l)
200
3
3
7
1
100
700
2000
1
B . *
asJ.s
1, 1, l-Trichloroethane
l,l-Dichloroethane
l,2-Dichloroethane
l,l-Dichloroethene
Benzene
Chlorobenzene
Ethyl Benzene
Toluene
Vinyl Chloride
PDWS
PDWS**
PDWS
PDWS
PDWS
pMCL
pMCL
pMCL
PDWS
*PDWS = State of Florida primary drinking water standard
pMCL = Proposed federal maximum contaminant level
**In the absence of sufficient toxicity data, the primary
drinking water standard for the structurally similar compound,
. l,2-dichloroethane, will be used. .
,,'
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-33-
10.0
Statutory Determinations
The U.S. EPA has determined that this remedy will satisfy the
statutory requirements of Section 121 of CERCLA by providing
protection of human health and the environment, attaining ARARs,
providing cost-effectiveness, and utilization of permanent solutions
ahd alternative treatment technologies to the maximum extent
practicable. Sections 10.1 and 10.5 below are the statutory
requirements for this site.
10.1
Protective of Human Health and the Environment
The selected remedy adequately protects human health by reducing the
risk of potential consumption of contaminated ground water. ~his
will be accomplished through the prevention of potential migration
and capture of the remaining ground-water contaminant plume. No
unacceptable short-term risks will result from the implementation of
this z::emedy.
10.2
Attainment of the Applicable or Relevant and Appropriate
Requirements (ARARs)
Remedial actions performed under CERCLA, as amended by SARA, must
comply with all applicable or relevant and appropriate requirements
(ARARs). The recommended alternative was found to meet or exceed the
ARARs. When ARARs are not available for specific compounds or
exposure media (such as soil), the cleanup goals are based on Agency
reference doses (R;D) for ioncarcinogens and a risk range for
carcinogens of 10- to 10-. The ground-water remediation goals
for the Sydney site are contained in Table 9.1 and are based on the
State of Florida primary drinking water standards or proposed federal
maximum contaminant levels.
The recommended alternative was found to meet or exceed the following
ARARs : I'.
Resource Conservation and Recovery Act (RCRA) location
reauirements (40 CFR Subpart X Miscellaneous Treatment Unit. 40
CFR Part 261 Land Ban. and' 40 CFR Part 264 Sub~art G Closure
and P08tclosure) - Mandates that hazardous waste treatment,
storage, or disposal facilities located within a 100-year
floodplain must be designed, constructed, operated, and
maintained to avoid washout. Examples of RCRA requirements
include minimum technology standards, monitoring requirements,
and storage and disposal prohibitions.
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-34-
Endanaered Species Act (Interaaencv Section 7 Consultation
Process, 50 CFR Part 402') -, Requires action to conserve
endangered or threatened species for activities in critical
habitats upon which these species depend. The Department of
Interior, Fish and Wildlife Service, and the Department of
Commerce, National Oceanic and Atmospheric Administration, are
presently being consulted to assure that endangered or
threatened species are not adversely impacted by this remedy.
Compliance Monitoring Proaram (40 CFR Section 264.99) -
Establishes criteria for monitoring ground-water quality when
, contaminants have been detected. This involves development of
a ground-water quality data base sufficient enough to
characterize seasonal fluctuations in ground-water quality at
the site.
Clean Water Act/Safe Drinkina Water Act,- Provides criteria for
ground-water remediation and discharge into surface waters.
EPA's determination of appropriate ground-water cleanup
criteria involved an evaluation of contaminant concentrations
'relative to available health-based standards. The ,limits
include Maximum Concentration Limits (MCLs) and Maximum,
Concentration Limit Goals (MCLGs), and federal Ambient Water
Quality Criteria (AWQC), Section 304 of the Clean Water Act
(CWA) used as prescribed in Section 121(d)(2)(b)(i) of CERCLA,
as defined by the Safe Drinking Water Act (SDWA) (40 CFR Parts
141 and 142) and the Clean Water Act.
,..
10.3
Cost-Effectiveness
,
The selected alternative, although more costly than the others,
provides a higher degree of protectiveness. The modified
ground-water recovery and treatment system will capture the plume and
reduce the contaminant concentrations to health-based levels. It
will also provide a more rapid attainment of these levels. The U.S.
EPA has determined that the cost of the selected remedy is
proportionate to the overall effectiveness and protection provided.
10.4
Utilization of Permanent Solutions and Alternative Treatment
Technologies to the Maximum Extent Practicable
The U.S. EPA believes the selected remedy is the most appropriate'
cleanup solution for the Sydney site and provides the best balance
among the evaluation criteria for the remedial alternatives
considered. This remedy provides effective protection in both the
short- and long-term to potential human and environmental receptors,
is readily implemented, and is cost-effective.
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-35-
Ground-water recovery and treatment represents a permanent solutior
through treatment which will effectively reduce and/or elLminate
mobility of hazardous wastes and hazardous substances into the
environment.
10.5
Preference for Treatment as a Principal Element
The statutory preference for treatment will 'be met because the
selected alternative will treat the principal threat from the SydnE
site, that is, the potential ingestion of contaminated ground wateJ
The selected remedy will reduce this risk through continuing
operation of the existing ground-water recovery and treatment SYStE
with evaluatioa and modification, if necessary, to increase
efficiency and effectiveness.
-------
APPENDIX A
SITE DATA
Sydney Mine Sludge Ponds Site
" Hillsborough County, Florida
I .
I
-------
~
I~
a
DATA SUMMARY FOR MONITOR WELL BV-1 ; JANUARY - APIUL 1989
GEOMETRIC
NUMBER OF COMPOUND MEAN
SAMPLING DETECTED CONC.b RANGE
PARAMETER EPISODES # (ppb) (ppb )
Vinyl Chloride 9 7 . . 12.0 <4-24
Chloroethane 9 5 5.4 <3-10
Methylene Chloride 2c 2 16.7 9-31
l,l-Dichloroethane 9 9 30.6 12-43
Trans-1,2-Dichloroethene 9 5 5.7 <4-11
Cis-1,2-Dichloroethene 2c '1 2.8 <4-4
1,2-Dichloroethane 9 7 5.3 4.6-<10
Tert Butyl Methyl Ether 5c 5 44.1 20-168
Benzene 9 9 90.2 45-150
Toluene 9 9 28.3 12-40
Ethylbenzene 9 5 2.6 1. 5-<10
o,m,p-xylene 9 6 6.63 <4-12
Naphthalene 2c 2 7.2 4-13
a Bone Valley Formation - 1 monitoring well.
b Geometric mean includes one-half the detection limit fcr values reported
as non-detected.
c
Only reported GC/MS analyses (EPA Method 624) .
performed by GC (EPA Methods 601/602).
All other analyses
d
Not reported for all sampling episodes.
-------
DATA SUMMARY FOR OPRW COMPOSITE3; JANUARY - APRIL 1989
PARAMETER
Vinyl Chloride
Chloromethane
Dichloromethane
1,1-Dichloroethene
1,l-Dichloroethane
Trans-1,2-Dichloroethene
1,1,l-Trichloroethane
Trichloroethene
Benzene
Toluene
Ethyl Benzene
Xylene total
GEOMETRIC
NUMBER OF
SAMPLING
EPISODES
3
•3
•J
•J
J
3
COMPOUND
Detected
*
2
A
3
-------
DATA SUMMARY FOR DIKE DISCHARGE COMPOSITE ; JANUARY - APRIL 1989
PARAMETER
Vinyl Chloride
Chloroetharie
Dichloromethane
1,1-Dichloroethene
1,1-Dichloroethane
Trans-1,2-Dichloroethene
Cis-1,2-Dichloroethene
Chloroform
1,2-Dichloroethane
1,1,1-Trichloroethane
Trichloroethene
Benzene
Toluene
Ethylbenzene
o,m,p-xylene
o-xylene
m-xylene
p-xylene
Ter.tbutylbenzene
1,2,4-TrimetyIbenzene
1,3-Dichlorobenzene
1,2-Dichlorobenzene
1,4-Dichlorobenzene
p-Isopropyltoiuene
Naphthalene
NUMBER OF
SAMPLING
EPISODES
15
15
15
15
15
15
2°
15
15
15
15
15
15
15
15
2C
2C
2C
2°
2C
15
15
15
2C
2C
COMPOUND
DETECTED
#
14
14
14
8
15
13
2
2
8
14
10
15
15
13
14 '
2
1
2
1
2
1
2
1
2
2
GEOMETRIC
MEAN .
b
CONC.
(ppb)
20.2
49.5
28.3
4.8 '
. j.4
20,2
12.4
3.8
5.7
38.3
5.2
115.2
233.9
10.9
38.2
16.5
3
8.8
2.7
7.5
3.8
4.2
4.0
2.7
4.2
RANGE
(ppb)
<10-46
<3-200
<10-62
<3-8.3
72-230
<3-57
11-14
<3-8.3
<3-18
<10~70
<3-18
73-160
140-310
5-18
<10-65
16-17
<3-6
6-13
3-<5
7-8
<1-6.1
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Summary of Semi-Volatile Organic Data in Groundwater
for Representative Areas: February 9, J.»oy
CONCENTRATIONS (ppb)
CONSTITUENT/LOCATION BV-1 SRW-1 SRW-7 52li 2£li
2-Metylnapthalene 30 <10
Napthalene <10 H
,, n 1C *m
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APPENDIX B
RESPONSIVENESS SUMMARY
Sydney Mine Sludge Ponds Site
Hillsborough County, Florida
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RESPONSIVENESS SUMMARY
The United States Environmental Protection Agency (EPA) and the
Florida Department of Environmental Regulation (FDER) established a
public comment period from September 8, 1989 through September 29,
1989 for interested parties to comment on EPA's and FDER's Proposed
Remedial Action Plan (PRAP) for the Sydney Mine Sludge Ponds Site
(Sydney). A public meeting was conducted by EPA on Wednesday,
September 13, 1989. The public meeting was held at the Brandon
Recreation Center in Brandon, Florida. The meeting presented the
studies undertaken and the preferred remedial alternative for the
site.
A responsiveness summary is required by Superfund policy to provide a.
summary of citizen 'comments and concerns about the site, as raised
during the public comment period, and the responses to those
concerns. All comments summarized in this document have been
factored into the final decision of the preferred alternative for
cleanup of the Sydney site.
This responsiveness summary for the Sydney site is divided into the
following sections:
I.
OVerview This section discusses the recommended
alternative for remedial action and the public reaction to
this alternative.
III.
Backaround on Community Involvement and Concerns This
section provides a brief history of community interest and
concerns regarding the Sydney site.
Summary of Maior Ouestions Received Durina the Public
Comment Period and EPA's or FDER's Responses This section
presents both oral and written comments submitted during the
public comment period, and provides responses to the~e
comments.
II.
IV.
RamAinina Concerns This section discusses community
concerns that EPA should be aware of in design and
Lmplementation of the remedy.
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I.
Overview:
The preferred remedial alternative was presented to the public in a
public meeting held on September 13, 1989. The recommended
alternative for remediation of the ground water is presented in the
Record of Decision (ROD). The major components of the recommended
alternative include:
Continued operation of the existing ground water recovery
and treatment system;
Continued monitoring (sampling and analysis) of the ground
water;
,r"
Evaluation and modification, if necessary, of the existing
ground water recovery and treatment system to improve the
effectiveness and efficiency.
The community, in general, favors the selection of the recommended
alternative.
II.
Background on Community Involvement and Concern:
The Brandon community and Hillsborough County have been aware of the
contamination problem at the Sydney site for several years. Since
1982, the Hillsborough County Department of Public Utilities has
performed voluntary remedial actions at the site and has continued to
involve the community in their actions.
EPA conducted a public meeting on September 13, 1989. The, purpose of
this meeting was to present the recommendations of EPA and FDER for
the remaining remedial actions needed to complete 'the site cleanup.
Additionally, the purpose of this meeting was to accept questions and
comments from the public on the site and its cleanup. At this
meeting, the key issue identified was:
Public Notice: The public wanted to better informed of public
meetings and site activities.
III. SummarY of Major Questions and Comments Received Durina the
Public Comment Period and EPA's or FDER's Responses:
1. )
One attendee inquired about how many people from the public
were in attendance at the public meeting.
EPA Response: A total of twelve (12) people attended the public
meeting. Additionally, five (5) people from EPA attended.
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2. )
One attendee expressed concern about the method used to inform
the public about the public meeting and felt that adequate
notice had not been given.
EPA ReSDonse: On September 6, 1989, EPA sent the Sydney Site
Proposed Plan to all names on the site mailing list. EPA also put
out a press release a~d a public notice prior to the public meeting.
EPA agrees that'this was shorter notice than desirable; however, the
public comment period was scheduled to remain open until September
29, 1989. This schedule provided plenty of tLme for the public to
submit comments.
3. )
One attendee inquired how close contaminated ground water is to
the Hawthorn Formation and how will Alternatives 2 and 3 stop
the migration of the contaminants.
EPA ReSDonse: The site has been considerably disturbed by the past
mining activities; therefore, tailing sands are overlying the
aquifers. There has been some contamination detected in the tailing
sands and in the upper mine zone of , the site. Contamination has not
been detected in.the Hawthorn Formation; ho~ever, confining layers do
not completely cross the mined zone. Alternatives 2 and 3 both
recommend continuation of the ongoing ground-water recovery and
treatment system. The goal of the system is to reduce the potential
for migration of contaminants to the Hawthorn Formation by drawing
the contaminants to the surface for treatment.
4. )
One attendee inquired about the direction of ground-water 'flow
in the area of the site.
EPA ResDonse: The prLmary directions of perched ground-water
movement are north, northwest, and east.
5. )
One attendee inquired how far is the worst part of the
contamination.
EPA ResDonse:
the site.
The contamination extends approxLmately 400 feet from
6 . )
One attendee asked who are the potentially responsible parties
(PRPS) and if legal action could be taken to recover site costs
from the PRPs.
EPA ReSDonse: ApproxLmately fifty (50) entities have been identified
as PRPs which include current owners and operators, former owners and
operators, generators of waste which was brought to the site, and
transporters who arranged for the transport of waste or directed that
waste be taken to the site. Since June 1, 1989, five (5) PRPs have
been under a 106 Unilateral Order to operate and maintain the
existing treatment system and sampling program. Three PRPs are
complying with the Order and two are in violation of the Order.
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From 1982 until June 1, 1989, Hillsborough County voluntarily pursued
cleanup of the site and has the right to take legal action against
other PRPs to recover their costs.
7 '. )
One attendee inquired if EPA is pursuing action against the two
PRPs who are in violation of the 106 Unilateral Order.
EPA Response:
Yes.
8. )
One attendee inquired about kerosene that was spilled at the
phosphate mines and if we can require the past owner, American
Cyanamid Corporation, to clean up the spill..
EPA ResDonse: The EPA technically reviews concentrated sources at
sites for inclusion on the National Priorities List (NPL) and for
remedial action. The identified threat at the Sydney site was the
heavily concentrated waste at the disposal site, not the alleged
kerosene spill. Presently, EPA's focus is the cleanup of a 9.5 acre
former waste disposal area which is located on the 1,700 acre former
phosphat~ mining site. 'American Cyanamid is a PRP in connection with
the disposal area and is considered'part of the fifty (50) PRPs
previously mentioned.
One attendee inquired about who is now operating the
ground~water recovery and treatment system at the site.
EPA Response: An environmental consulting firm, CH2M Hill, is
presently operating the treatment system under contract with the
PRPs. This is the same contractor who installed and operated the
system for the County. Therefore, the same company is doing the work
but the cost is no longer being paid by the County.
9. )
10. )
One attendee inquired what is the most dangerous contaminant
that was found at the site.
EPA ResDonse: The most common contaminant
carcinogen, benzene. From a public health
. a number of contaminants found at the site
harmful.
found at the site is the
point of view, there were
that would be considered
One attendee inquired if waste is no longer being placed at the
site, then where is it. being placed.
EPA Res90nse: Opera~ing facilities are regulated under the Resource
Conservation and Recovery Act (RCRA) of 1976 and its later
amendments. RCRA requires that these types of wastes be disposed of
properly with one option being deposition at a hazardous waste
disposal area. There are no hazardous waste disposal areas in
Florida; therefore, the waste must be shipped out of the state to
hazardous waste disposal areas in other states. .
11.)
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IV.
Remainina Concerns:
The community's concerns 'surrounding the Sydney site will be
addressed in the follow!ng areas: incorporation of
comments/suggestions in the remedial design and remedial action; and
community relations support throughout the remaining phases of this
project.
'Community relations should consist of making available final
documents in a timely manner, to the local repository, and issuance
of fact sheets to those on the mailing list to provide the community
with project progress and a schedule of events. The community will
be made aware of any principal design changes made during the
project.' At any time during remedial design or remedial action, if
new information is revealed that could affect the implementation of
the remedy, or, if the remedy fails to achieve the necessary design
c~iteria, the Record of Decision may be revised to incorporate new
technology that will attain the necessary performance criteria.
Community relations activities will be an active aspect of the
remaining phases of this project.
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APPENDIX C
STATE CONCURRENCE MEMORANDUM
Sydney Mine Sludge Ponds Site
Hillsborough County, Florida
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