United States
Environmental Protection
Agency
Office of
Emergency and
Remedial Response
EPAIRODIR05-93/245
July 1993
PB94-964~OS
&EPA
Superfund
Record of Decision:
u.s. Air Force
Wright-Patterson AFB, OH
~
Hazardous Waste Collection
Information Resource Center
US EPA Region 3
Philadelphia, PA 19107
IEPA ~sp())ri t«D .~l?)tiio~ =
iruti)Jrmra~'l!m ~~$@8J]rt@ ~@@~~r -
US If~~ OOQWJ~@[j\) 3
PhnID@!@I~~9 [?b\ ~~~(ID(1
-------
4.
50272.101
REPORTDOCUMENTAT10N 11. REPORT NO.
PAGE EPA/ROD/R05-93/245
Title and Subtitle
SUPERFUND RECORD OF DECISION
Wright Patterson Air Force Base, OH
First Remedial Action
Author(.)
2.
3. Recipient'. k:e_1on No.
~
Report Date
07/15/93
&
7.
8.
Perfonnlng Organization Rep(. No.
8.
Performing Organization Narne and Addl'888
10
Project TuklWork Unit No.
.,
Ii
11. Contract(C) or Grart(G) No.
(C)
(G)
12. SpoMorIng Organization Narne and Address
U.S. Environmental Protection
401 M Street, S.W.
Washington, D.C. 20460
13. Type of Report & PerIod Cov8I8CI
Agency
800/800
14.
15. Supplementary Not.
PB94-96410S
16. Abstract (Limit: 200 words)
The 21-acre Wright Patterson Air Force Base site is a portion of an active military
facility located in Greene County, Ohio, approximately 60 miles north of Cincinnati.
Land use in the area is predominantly residential and military. Most of the Wright
Patterson Air Force Base (WPAFB) is situated within the Mad River floodplain. . The
buried valley aquifer, a federally-designated sole-source aquifer, is the primary unit
utilized for both municipal and WPAFB water supplies. The installation is composed of
two fields: Wright Field (comprised of Area B) and Patterson Field (comprised of Areas
A and C ). The northeast corner of Area B contains two landfills, known as Landfills 8
and 10, respectively. The Woodland subdivision, a WPAFB housing subdivision, occupies
the area north of Landfill 8 and to the north and south of landfill 10. Additionally,
the area surrounding the landfills is drained by an unnamed tributary flowing north to
Hebble Creek, which divides the landfills. The II-acre Landfill 8 operated from 1947
until the early 1970s and received approximately 187,300 yd3 of waste, including
general refuse and hazardous materials, from Area B. The 8-acre Landfill 10 operated
from 1965 until the early 1970s and accepted approximately 171,600 yd3 of general
refuse and hazardous waste from all areas of WPAFB. Initial Air Force investigations
(See Attached Page)
17. Document Analysis a. D8sc:riptors
Record of Decision - Wright Patterson Air Force Base, OH
First Remedial Action
Contaminated Media: soil, gw, leachate
Key Contaminants: VOCs (benzene, TCE, toluene), other organics (dioxins, PAHs, PCBs,
pesticides), metals (arsenic, lead), other inorganics (cyanide)
b.
Id8ntlfieratOpen
-------
EPA/ROD/R05-93/245
Wright Patterson Air Force Base, OH
First Remedial Action
Abstract (Continued)
in 1984 and 1986 involved installation of monitoring wells and leachate/landfill gas wells
and sampling of area media. Based on the results of these investigations and the
proximity of homes to the two landfills, it was determined that action to mitigate current
or potential risks from the migration of contaminants is warranted. Th~ site has.been
divided into twelve OUs for remediation. This ROD addresses contaminated soil, ground
water, and leachate from beneath and upgradient of the landfills, and air at Landfills 8
and 10, as OU1. Future RODs will address a final remedy for ground water, and.
specifically any off site migration of contamination. The primary contaminants of concern
affecting the soil, ground water, and leachate are VOCs, including benzene, TCE, and
toluene; other organics, including dioxins, PAHs, PCBs, and pesticides; metals, including
arsenic and lead; and other inorganics, including cyanide.
The selected remedial action for this site includes destroying the existing partial cap on
Landfill 10 due to its incompatibility and leaving it in place; capping the two landfills
with a recompacted 2-foot layer of clay, a drainage layer, and a soil and vegetative
cover; installing an active leachate collection system around both landfills that will
convey to an equalization tank onsite; installing gas collection wells, vents, or layers
to intercept landfill gas, followed by discharge of the collected gas to an enclosed
ground flare; treating extracted leachate onsite by using a coagulant to precipitate out
metals such as iron and manganese, followed by flocculation and clarification of the
material; using a packaged biological activated sludge wastewater treatment system to
remove biodegradable organics, followed by filtration to remove biological solids, other
organics, and some metal precipitants from the activated sludge effluent; using activated
carbon adsorption to remove the non-biodegradable organics, followed by effluent
reaeration to meet the dissolved oxygen standard; using ion exchange, if necessary, to
meet surface water discharge requirements; discharging the treated leachate effluent
onsite to surface water; regenerating spent carbon; disposing of sludge generated from the
metals and biological treatment processes in accordance with applicable regulations;
providing an alternate water supply to nearby homes that use private wells for drinking
water; conducting air, explosive gas, and ground water monitoring; and implementing
institutional controls, including land use and deed restrictions. The estimated present
worth cost for this remedial action is $30,423,202, which includes an estimated annual O&M
cost of $1,729,799 for years 0-5 and $1,700,158 for years 6-30.
PERFORMANCE STANDARDS OR GOALS:
Chemical-specific soil cleanup goals are based on State regulations or risk-based
concentrations calculated using a specific exposure pathway of direct ingestion and a
residential land use scenario, and include benzo(a)pyrene 0.0557 ug/kg; beryllium 0.149
ug/kg; dieldrin 0.04 ug/kg; dioxins 0.00000426 ug/kg; and PCBs 0.0831 ug/kg. Chemical-
specific leachate in ground water cleanup goals are based on State action levels, Federal
MCLs/MCLGs, or risk-based concentrations calculated using specific exposure pathways of
direct ingestion and inhalation of volatiles from using household water, and include
arsenic 11 ug/l; benzene 0.62 ug/l; beryllium 0.02 ug/l; dioxin 0.000000567 ug/l; and TCE
3.03 ug/l.
-------
Record of Decision:
c,
Source Control Operable Unit -
Landfills 8 and 1 0
Wright-Patterson Air Force Base
Greene County, Ohio
. .
C"
. j
Prepared by:
Restoration Branch
Office of Environmental Management
645th Air Base Wing
(645 ABW/EMR)
Wright-Patterson AFB, OH 45433
, .-,
Co
: . .
, .
.. "'.
.'
r" ...
~'.
.~ ,
-..-Final
Submitted: 24 May 1993
-------
Table of Contents
I.
The Declaration
1
c,
A. Site Name and location
B. Statement of Basis and Purpose
C. Assessment of the Site
D. Description of Selected Remedy
E. Statutory Determination
1
,
1
1
2
II.
Decision Summary
3
A. Site Name, location, and Description
B. Site History
C. Highlights of Community Participation
D. Scope and Role of Response Action Within Site Strategy
E. Summary of Site Characteristics
F. Summary of Site Risks
G. Description of Alternatives
H. Summary of the Corriparitive Analysis of Alternatives
I. The Selected Remedy
J. Statutory Determination
K. Documantation of Significant Change
3
6
7
7
8
11
13
26
31
41
45
III.
Responsiveness Summary
46
A. Overview
B. Background on Community Involvement
C. Summary of Public Comments and Agency Response
D. Remaining Concerns
46
46
47
65
Attachment 1 - Community Relations Activities for Landfills 8 and 10
Attachment 2 - Admistrative Record Index for landfills 8 and 10
66
68
-------
List of Figures
Figure 1 - Area location Map 4
Figure 2 - location of landfills 8 and 10, and Area Housing Units 5
Figure 3A - Conceptual Plan Drawing of Clay Caps for landfills 8 and 10 15
Figure 38 - Generalized Cross-Section Detail for Clay Caps through
landfills 8 and 10 16
Figure 4 - Active landfill Gas Collection/Treatment System for
landfills 8 and 10 17
Figure 5A - Preliminary location of leachate Collection and Treatment
Systems for landfills 8 and 10 18
Figure 58 - .leachate Extraction Wells for landfills 8 and 10 19
Figure 6 - Alternative 2 leachate Treatment System 21
Figure 7 - Alternative 3 leachate Treatment System Z3
Figure 8 - Alternative 4 leachate Treatment System 2S
-------
List of Tables
Table 1 - Environmental Media and Potential Hazards 8
Table 2 - Chemicals of Concern "
Table 3 - Comparison of Chemicals of Concern with PRGs 12
Table 4 - Annual Removal Rates for Chemicals of Concern 28
Table 5 - Cost Comparison for Alternatives 29
Table 6 - Summary of Remedy Costs 37
Table 7 - Performance Standards for the Selected Remedy 38
Table 8 - Compliance levels for the Chemicals of Concern 40
-------
Rscord of Dscision: Sourc8 Control Operable Unit - Landfills 8 and 70
I.
THE DECLARATION
A.
Site Name and Location
u
Source Control Operable Unit - Landfills 8 and 10
Wright-Patterson AFB
Greene County, Ohio.
(CERCLIS Operable Unit 1, Event 2)
B.
Statement of Basis and Purpose
This decision document presents the selected remedial action for the Source
Control Operable Unit, Landfills 8 and 10, at Wright-Patterson AFB,
developed in accordance with CERCLA, as amended by SARA, and, to the
extent practicable, the National Contingency Plan (NCP). This decision is
based on the administrative record for the site. The attached index identifies
. the items which comprise the administrative record upon which the selection of
the remedial action is based.
The State of Ohio has concurred on the selected remedy.
C.
Assessment of the Site
Actual or threatened releases of hazardous substances from the 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.
D.
Description of Selected Remedy
Landfills 8 and 10 comprise the first of twelve operable units identified for
cleanup at Wright-Patterson AFB, Ohio. This ROD addresses the sources of
the contamination and any threat posed by migration of contamination to
groundwater beneath Landfills 8 and 10, the principle threats to the site.
Based on the proximity of homes to Landfills 8 and 10, WPAFB, OEPA and
USEPA jointly deemed that a remedial action aimed at controlling any current
or potential risks posed by the contamination migrating from the landfills was
warranted. WPAFB and the regulatory agencies agreed there was no reason to
delay that portion of the overall site remedy dealing with the landfills
themselves while awaiting sampling results from areas outside, but potentially
affected by, Landfills 8 and 10. A subsequent ROD will address potential
off-source contamination for the operable unit.
Page 1
-------
Record of Decision: Source Control Operable Unit - Landfills 8 and 10
The remedial actions selected in this ROD incorporate the following
components:
.
.
.
.
..
.
Low Permeability Clay Cap.
Leachate Collection and Treatment.
Landfill Gas Collection and Treatment.
Public Water Supply for Private Well Users.
Operation and Maintenance and Performance Monitoring.
Disposal of Nonhazardous Drill Cuttings under the Clay Cap.
E.
Statutory Determination
The selected remedy is protective of human health and environment, complies
with Federal and State requirements that are legally applicable or relevant and
appropriate to the remedial action, and is cost-effective. This remedy utilizes
permanent solutions and alternative treatment or resource recovery
technologies, to the maximum extent practicable. However, because treatment
of the principal threats of the site was not found to be practicable, this remedy
does not satisfy the statutory preference for treatment as a principal element.
Because this remedy will result in hazardous substances remaining on-site
above health-based levels, a review will be conducted within five years after
commencement of the remedial action to ensure that the remedy continues to
provide protection of human health and the environment.
,(;r;~ j/~M1t ~/; t: V,
ALAN P. BABBITT Valdas ~. Adamkus
Deputy for Hazardous Materials Region Administra r
and Wast~ USEP Region V
Deputy Ass1stant Secretary ,
of the Air Force
(Environment, Safety and
Occupational Health)
\l~ O.~ o.e~~)7),vI1~'G~~~~-4'
o Ohio Enviromhental'1>rotection Agency 0
Page 2
-------
Record of Decision: Source Control Operable Unit - Landfills 8 and 10
II.
DECISION SUMMARY
A.
Site Name, Location, and Description
{j
Wright-Patterson Air Force Base (WPAFB) is located in southwestern Ohio, east of the City
of Dayton and adjacent to Fairborn. The Base is approximately 60 miles north of Cincinnati
and approximately 50 miles west of Columbus.
The installation is composed of Wright and Patterson Fields, which are separated by State
Route 444. Wright Field comprises Area B and Patterson Field comprises Areas A and C.
Landfills 8 and 10 are located in Area B.
. Landfills 8 and 10 are located in the northeast comer of Area B, in the area bounded by
National, Kaufman, and Zink Roads (Figures 1 and 2). Landfills 8 and 10 are separated by
roughly 1,000 feet. An unnamed tributary to Hebble Creek runs through the area between
the landfills. Currently, the entire area encompassing Landfills 8 and 10 is fenced and
posted as "Off Limits".
Landfills 8 and 10 are adjacent to the Woodland Hills military housing area at WPAFB. In
addition, there are private homes on Zink and National Roads, and a subdivision is currently
under construction in the area south of the landfills.
Geo2raphy: WPAFB lies within the Till Plains section of the Central Lowlands
Physiographic Province. The regional land surface typically appears flat to gently rolling.
Area streams and rivers have developed generally level flood plains, such as the Mad River
flood plain on which most of WP AFB is situated.
The land surface altitude at WP AFB varies from 800 feet above the National Geodetic
Vertical Datum of 1929 (NGVD) in Areas A and C, located within the Mad River flood
plain, to 975 feet above NGVD in Areas B just west of Landfill 8. Landfills 8 and 10 are
located in a high area that overlooks the Mad River valley. The land surface altitude in the
vicinity of Landfill 8 is 945 feet above NGVD; in the vicinity of Landfill 10, the land
surface altitude is 920 feet above NGVD. The Mad River valley immediately north of the
landfills is located about 800 feet above NGVD.
The area surrounding the landfills is drained by an unnamed tributary to Hebble Creek. This
unnamed tributary separates the landfills and flows north to Hebble Creek.
The Woodland Hills subdivision occupies the area generally north of Landfill 8 and the areas
generally north to south of Landfill 10. The subdivision houses WP AFB personnel.
Both landfills support several small stands of cattails that have developed in saturated
depressions on the landfill caps. The depressions are the result of compaction and settling of
Page 3
-------
f
a.
Q
.....
t)
CD
Q
lit'
A'
::)
"
~
~
~
g
~
...
~
~
~
it
5=
;:;"
,...
~
~
~
ii;"
Q)
~
Q,
....
c
!
'11'
!
COLUMBUS
SPRINGfiELD
.'
-
1-70
Wrtght-Petterson AFB
1-70
'TI
cO' ,-,:;
c
...
(II
..a XENIA
;;? »
...
(II
(Q OJ
Ib ,....
~ 0
n
III
...
ci"
:;]
s:
III
'C
o
I
10
I
I
MILES
-------
R8Cord of D8Cision: Source Control Operable Unit - Landfills 8 and 10
,
..,
L
Figure 2 . Location of Landfills 8 and 10. and Area Housing Units
Page 5
-------
Record of Decision: Source Control Operable Unit - Landfills 8 and 10
the cap material. Landfills 8 and 10 support two and eight cattail stands. respectively, that
total about 3,450 square feet (about 0.08 acre). Mean stand size is less than 0.01 acre.
A new subdivision is currently under construction in the area immediately south of Landfills
8 and 10. There are also private homes along National Road, within 300 feet of Landfill 8,
and private homes along Zink Road, within about 1,000 feet of Landfill 10.
Climate: The climate in the area is temperate and humid with a mean annual temperature of
52.3 degrees Fahrenheit (oF) and a mean annual precipitation of 36.25 inches. Precipitation
is evenly distributed throughout the year. In the, spring, the average final occurrence of
freezing temperatures is in mid-April, and in the autumn, the average initial occurrence of
freezing temperatures is in late October. Temperatures of 00 F or below will be experienced
in about four years out of five, while l000F or higher will occur in about one year out of
five.
B.
Site History
Historv of Site Activities: Landfill 8 is about 11 acres. It was operated from about 1947
until the early 1970s and received waste from Area B. Both general refuse and hazardous
materials were disposed in the landfill using trench-and-cover methods. The depth of
Landfill 8 varies across the refuse trenches from 6 to 44 feet. The thickness of the cover
varies between 3 and 12 feet. The total volume of waste material buried at Landfill 8 is
estimated at 187,300 cubic yards.
Landfill 10 is about 8 acres. It was operated from 1965 until the early 1970s and received
waste from all areas of WPAFB. Like Landfill 8, both general refuse and hazardous
materials were disposed in Landfill lOusing trench-and-cover methods. The depth of the
landfill varies across the refuse trenches from 17 to 25 feet, and the cover thickness is
typically 1-3 feet. The total volume of waste material buried at Landfill 10 is estimated at
171,600 cubic yards.
History of Site Investieations and Remedial Actions: Several investigations were
conducted at Landfills 8 and 10. A records search was conducted in 1981. A field
investigation, which included the installation of monitoring wells and leachate/landfill gas
wells, the sampling of surface water, leachate and groundwater and the performance of
geophysical surveys, was conducted in 1984. A follow-on field investigation was conducted
in 1986, which included the installation of additional monitoring wells, the sampling of
groundwater ftom both new and existing wells, shallow borings to investigate landfill covers
and estimate infiltration to the landfills, and monitoring landfill cover borings and
leachate/landfill gas wells for hydrogen sulfide and combustible gas concentrations. This
investigation was followed by an additional field study, which included resampling the
ground-water monitoring wells, sampling leachate, and sampling surface waters and
sediments along the unnamed tributary between Landfills 8 and 10.
Three corollary investigations were conducted during the preliminary stage of the Remedial
Page 6
-------
Record of Decision: Source Control Operable Unit - Landfills 8 and 10
Investigation/Feasibility Study (RI/FS) for Landfills 8 and 10. These included soil gas
surveys, additional geophysical surveys, and a study to identify combustible gas migration
from the landfills.
C.
Highlights of Community Participation
Wright-Patterson AFB offered many opportunities for public input and community
participation during the Remedial Investigation and Feasibility Study for Landfills 8 and 10,
and the proposed plan for the Source Control Operable Unit. Specifically, the base held
three public meetings during an eighteen month time period to discuss the investigatory
activities taking place at the site. At each of these meetings, the fieldwork for the landfills
was discussed as well as the methane migration study and methane monitoring program. A
listing of community relations activities is contained in attachment I of this ROD.
Base officials also conducted a special meeting with 14 Woodland Hills residents directly
affected by the methane migration study and methane monitoring program. A relocation plan
was developed by the Base Environmental Management Office for the 14 residents and was
approved by the Installation Commander. An emergency evacuation plan was in place in the
event that high methane levels were detected in homes where monitors were installed as a
precautionary measure. Local print and broadcast media were invited to this meeting in an
effort to keep the public informed of the actions the base took regarding the investigation.
A public comment period was held from October 23, 1992 until November 23, 1992 for the
Proposed Plan for the Source Control Operable Unit at Landfills 8 and 10. The public
comment period was later extended for an additional 30 days, and base officials accepted
comments until December 23, 1992. A summary of the comments received can be found in
the responsiveness summary.
D.
Scope and Role of Response Action Within Site Strategy
Based on the proximity of homes to Landfills 8 and 10, WPAFB, OEPA and USEPA jointly
deemed that a remedial action aimed at controlling any current or potential risks posed by the
contamination migrating from the landfills was warranted. WP AFB and the regulatory
agencies agreed there was no reason to delay that portion of the overall site remedy dealing
with the landfills themselves while awaiting sampling results from areas outside, but
potentially affected by, Landfills 8 and 10. They further agreed that initial data from the
ongoing Remedial Investigation would be sufficient for selecting appropriate source control
measures for the landfills without compromising the eventual selection or implementation of
an overall site remedy, which will be based on completion of the RI/FS for the study area
outside the immediate landfill boundaries.
This Record of Decision refers to the "source control operable unit" (SCOU). The scau is
a discrete portion of the overall remediation (clean-up) of Landfills 8 and 10. The scau
addresses hazards posed by specific environmental media and is not meant to address all
potential hazards posed by the site. Specifically, the SCOU addresses the following
Page 7
-------
Record of Decision: Source Control Operable Unit - Landfills 8 and 10
environmental media and potential hazards.
ENVIRONMENTAL MEDIA POTENTIAL HAZARD
,
Landfill wastes and soils Direct Contact and ingestion
Leachate Direct Contact and ingestion
Landfill gases Inhalation and fire/explosion
Ambient (breathing) air Inhalation
Private water sources Direct Contact, ingestion, inhalation
Table 1: Environmental Media and Potential Hazards
The most significant environmental medium which is not addressed by the SCOU is ground
water already affected by Landfills 8 and 10 (i.e., down gradient). The clean-up of ground
water already affected by the site will be addressed, if necessary, by an off-source
remediation effort scheduled for proposal in the fall of 1993. A detailed investigation of the
ground water at Landfills 8 and 10 is currently underway.
In general terms, the clean-up goals for the SCOU are to prevent direct contact with on-site
contaminants and to prevent on-site contamination from spreading. An additional goal of the
SCOD is to eliminate the potential for exposure to site-related contaminants through the use
of private water sources for drinking and showering. The SCOD remediation will achieve
the clean-up goals through a combination of waste containment and treatment, and the
remedy will address air, soil, and ground water from beneath and up gradient of the
landfills.
Meeting these goals plays an important role in the overall clean-up strategy for the site. By
initiating the SCOD remedial action as early as possible, risks posed by contact with landfill
contaminants will be significantly reduced or eliminated.
E.
Summary of Site Characteristics
Site Geolo!!v and H ydroloey. The geology of the area consists of Ordovician- and Silurian-
Age rocks overlain by unconsolidated deposits of Pleistocene Age and Recent Age.
The Richmond Group of Ordovician Age is the bedrock unit underlying most of WPAFB.
The Richmond Group consists of up to 265 feet of interbedded shales and limestones that
crop out in portions of eastern Montgomery and Western Greene Counties.
The Richmond Group is capped by thin, discontinuous erosion remnants of Brassfield
Limestone of Silurian Age in some areas of WPAFB. The Brassfield Limestone is a
relatively pure limestone up to 30 feet thick.
Page 8
-------
Record of Decision: Source Control Operable Unit. Landfills 8 and 70
The bedrock reflects a preglacial drainage system that differs somewhat from that currently
seen in the area. This drainage system is masked by overlying unconsolidated glacial
deposits.
Unconsolidated materials of the Pleistocene Age overlie bedrock and are represented in the
area by glacial till and outwash deposits. These materials were deposited during the last
period of major glaciation, the Wisconsin, and are present throughout the area.
Glacial till consists of a heterogeneous mixture of cobbles. gravel. sand, silt and clay that
were deposited directly by the glacier as it moved over the region. These deposits,
interbedded with water-bearing sand and gravel zones, locally may form confining aquifers
or may limit recharge to underlying unconsolidated aquifers.
As the glacier retreated, melt streams flowing through the valleys and lowlands deposited
large accumulations of sand and gravel identified as outwash deposits. Outwash deposits
attain a maximum thickness of 250 feet at Dayton and usually overlie till deposits. Outwash
deposits form the most prolific aquifer of the Ohio region.
Recent Age alluvium deposited in relatively thin sequences by modern streams is presented
the ground surface adjacent to all major streams. The alluvium consists of both sorted and
unsorted accumulations of sand, silt, gravel, and clay.
Water is present in the unconsolidated deposits and the underlying bedrock. Water occurs in
intergranular pore spaces in the unconsolidated deposits. In bedrock, water occurs in
fractures, joints, and solution openings in the shale and limestone.
The unconsolidated alluvium, outwash, and till interact to form a complex aquifer system at
WP AFB. Outwash is locally separated from overlying alluvial materials by 2 to 7 feet of
dense, unsorted till composed of clay, silt, gravel, and sand. In many areas, the till layer is
thin or absent and alluvium directly overlays the outwash deposits. Also, in many areas two
till layers occur within the glacial outwash, dividing it locally into separate hydraulic units.
The till, wherever it occurs, can be described as a semiconfining layer with many holes,
tears, and missing pieces.
Alluvial deposits may be locally productive, yielding 100 to 500 gallons per minute (gpm).
Normal practice in the Dayton area, however, is to obtain water supplies from the more
productive, underlying glacial outwash deposits. The alluvium, where present at WPAFB, is
typically 40 to 60 feet thick and occurs under water-table conditions. The alluvial deposits
provide base flow to streams during low flow periods.
Outwash deposits yield greater than 1,000 gpm. At WPAFB, the hydraulic conductivity of
the outwash ranges from 1,000 to 3,000 gallons per day per square foot (gpd/fr). The
buriect valley aquifer, a" Federally designated Sole Source Aquifer, is used by WPAFB for
water supply and is also the primary unit from which municipal supplies are drawn at the
nearby Dayton Municipal Well field on Rohrer's Island. The City of Fairbom's North
Page 9
-------
Record of Decision: Source Control Operable Unit - Landfills 8 and 10
Well field also draws water from this aquifer; this well field is used only during periods of
drought for emergency use. Groundwater occurs in the outwash deposits under both water
table and anesian conditions and locally may provide base flow to streams during low flow
conditions in areas where it is at or near the ground surface.
Groundwater contained in the scattered sand and gravel sequences of till provides domestic
supplies on the order of 10 gpm. The till is generally more than 20 feet thick and may
overlie units of greater productivity.
The bedrock deposits are a minor source of groundwater. The shale and interbedded
limestone of the Richmond Group yield water of sufficient quantity only for household use.
The Brassfield Limestone generally yields greater quantities of water than the Richmond
Group and is suitable for both farm and home use.
Nature and Extent of Contamination. Significant chemical contamination has been
detected at Landfill 8 and 10 in the soil, leachate, and landfill gases. Ambient (breathing) air
and private water sources in the vicinity of Landfill 8 and 10 have not shown significant
chemical contamination. However, the potential exists for these media to become
significantly contaminated in the future. The chemicals listed in Table 2 were detected at
concentrations which exceeded limits established by one or both of the following: (a) state
and/or federal environmental regulations, (b) a human health risk analysis (see Summary of
Site Risks).
The chemicals of concern were found to be unevenly distributed throughout both landfills,
which is expected from a trench-and-cover burial operation. Based on historical data and
data collected during the remedial investigation, no extremely high and isolated contaminant
concentrations, or "Hot Spots", were found that would indicate leaking buried containers or
localized hazardous waste disposal areas. Further, Landfills 8 and 1 0 were found to be
essentially the same in terms of the types and concentrations of contaminants. This
conclusion is important in that the clean-up alternative selected for the source control
operable unit will be the same at both landfills.
Page 10
-------
Record of Decision: Source Control Operable Unit - Landfills 8 and 10
I CHEMICALS OF CONCERN I
Soil/Sediment Landfill Gas
Range Range
Chemical (ug/kg) Chemical (ug/mJ)
Benzo(a)pyrene 31-1,200 Benzene 352 - 15,223
Dieldrin 89 - 290 Vinyl chloride 38 - 174,250
Dioxins (TCDD, pg/g) 1.9 - 54 Methane 426 - 6.5xl 08
PCBs 51 - 6,700
Beryllium 100 - 2,900
Leachate
Range Range
Chemical (ug/ll Chemical (ug/l)
1,2-Dichloroethene 4.0 - 16,000 Arsenic 4.7 - 68
4-Methylphenol 2.0 - 940 Beryllium 0.7-2.9
Benzene 2.0 - 100 Cadmium 3.6-10.1
Chloroform 2.0 - 5.0 Copper 3.0 - 142
Diethylphthalate 1.0 - 160 Iron 95 - 1.1 xl 06
Dioxins (TCDD, pg/l) 22 - 53 Lead 3.3 - 276
Ethylbenzene 2.0 - 150 Zinc 18.7 - 4,440
Methylene chloride 50 - 9,500 Ammonia 1,380 - 98,900
Naphthalene 1.0 - 390 Cyanide 10.9 - 148
Toluene 2.0 - 3,000
T richloroethene 1.0 - 930
Vinyl chloride 1.0 - 2,400
Table 2: Chemicals of Concern
F.
Sununary of Site Risks
The human health risk assessment for this SCOD was performed using a "qualitative"
methodology based on USEP A guidance found in the Human Health Evaluation Manual, Part
B, "Development of Risk-Based Preliminary Remediation Goals" (OSWER Directive 9285.7-
01B, December 1991). Chemical specific Preliminary Remediation Goals (PRGs) were
established. The PRGs were based on state and federal environmental regulations and/or
risk-based concentrations calculated using specific exposure pathways and land use scenarios.
The exposure pathways considered were direct ingestion of soil and ground water (leachate)
and inhalation of volatile contaminants from the use of household water. In addition, risks
associated with the migration of explosive gases from the landfills were evaluated. A
residential land use scenario was assumed.
Contaminant concentrations found at the site were then compared to the PRGs. If
contaminant concentrations at the site exceeded a PRG, significant risk to human health was
assumed to exist. If not mitigated, these contaminants at these concentrations pose an
Page 11
-------
Record of Decision: Source Control Operable Unit - Landfills 8 and 10
imminent and substantial endangerment to public health and welfare. Any such risk was
considered adequate justification for undertaking a clean-up action. The qualitative risk
assessment concludes that each of the pathways considered, including migration of explosive
gases, poses significant risks to human health. The chemicals of concern associated with the
pathways are listed in Table 3.
Soil/Sediment
Chemical mg/kg Location PRG (mglkg) PRG MCL
(Carcinogenic) (Non-Carcinogenic)
Benzo(a)pyrene 1.2 TP 8-23 5.6x10.2 NA NA
Dieldrin 0.29 TP 10- 1 3 4.0x10.2 1.35x10' NA
Dioxin (TCDD, pg/g) 5.36x10'& LS 10-2 4.27x10.8 NA NA
PCBs 6.7 TP 8- 13 8.3x10.2 NA NA
Berytium 2.9 TP 10-6 1 .5x1 0" 1.35x103 NA
leachate
Chemical mg/L Locetion PRG (mglll PRG (mg/l) MCL (mglll
(Carcinogenic) (Non-Carcinogenic)
1 .2-Dichloroethene 16.0 TP 8- 19 6.8x10.6 3.65x10" 7 .Ox1 0.2
4-Methytphenol 0.94 TP 10-2 NA 1.83 NA
Benzene 0.10 TP 10-31 6.2x10~ NA 5.0x1003
Chloroform 5.0x10.3 LS 10-3 2.7x10~ 3.65x10" 1.0x10"
Diethytphthalate 0.160 TP 10-6 NA 2.9x10' NA
Dioxins (TCDD, pglll 5.3x10-8 TP 8- 1 7 5.67x10"o NA 3.0x10-8
Ethytbenzene 0.150 TP 10-14 NA 3.3 7 .Ox1 0"
Methytene Chloride 9.5 TP 10-6 6.2x1003 2.14 5.0x1003
Nephthalene 390.0 TP 8- 19 NA 1.46x10.t NA
Toluene 3.0 TP 10-6 NA 6.6 1.0
Trichloroethene 0.930 TP 8- 1 9 3.0x10.3 NA 5.0x1003
Vinyl Chloride 2.4 TP 8-19 2.8x10'~ NA 2.0x10.3
Arsenic 6.8x10.2 TP 8-20 1.98x10.2 1 .1 x 1 0.2 5.0x10.2
Berytium 2.9x1003 TP 8-32 1.98x1003 1 .8x1 0.1 4.0x10-3
Cadmium 1.01x10.3 TP 10-14 NA 1.8x10.2 5.0x1003
Copper 0.142 TP 8-14 NA 1.35 1.3 (MCLG)
Lead 0.276 TP 8- 1 5 NA NA 0.015
Zinc 4.44 TP 10-14 NA 7.3 5.0 (SMCL)
Cyanide 0.148 TP 8-20 NA 0.73 0.20
Table 3: Comparison of Chemicals of Concern with PRGs
Page 12
-------
Record of Decision: Source Control Operable Unit - Landfills 8 and 70
Potential risks to the environment were not addressed in the qualitative risk assessment for
the SCOU, which focused on human health. Risks to the environment will be fully evaluated
in the baseline risk assessment- as part of the off-source remediation effort.
G.
Description of Alternatives
The Feasibility Study for the source control operable unit evaluated four clean-up
alternatives; one of which is the "No Action" alternative used as a baseline for comparison as
required under CERCLA and the NCP at 40 CFR 300.430 (e)(4). The remaining three
alternatives were found to be both effective and implementable, and all were evaluated
against nine criteria to arrive at the preferred alternative.
A brief description of each clean-up alternative follows. The reader will notice that
Alternatives 2, 3, and 4 are very similar. The only difference between the alternatives is the
method of leachate treatment. Therefore, the common elements of Alternatives 2, 3, and 4
are presented together, and the different leachate treatment methods are highlighted
individually. The costs presented for Alternatives 2, 3, and 4 include the common elements
and the specific leachate treatment method. The reader is encouraged to reference the SCOU
Feasibility Study for more detailed information.
Alternative 1: No Action
The No Action alternative shall involve no clean-up action at Landfills 8 and 10.
The costs and time to implement Alternative 1 are negligible. The No Action
alternative is intended as a basis for comparison for the other alternatives. Since
no clean-up action shall occur under this alternative, significant hazards, as
identified in the risk assessment for the SCOU, shall remain at the site.
Page 13
-------
Record of Decision: Source Control Operable Unit - Landfills 8 and 10
Common Elements of Alternatives 2. 3. and 4: Clay cap; leachate collection;
landfill gas collection & treatment; Public water supply
Alternatives 2. 3, and 4 each include construction of a low permeability clay cap
(Figures 3A, 38) to limit surface water infiltration. leachate generation. landfill gas
emissions. erosion. and contact with landfill contaminants. The clay cap shall
comply with Ohio EPA regulations for sanitary landfill closure (OAC 3745-27-12),
which meet or exceed requirements of RCRA, Subtitle D (40 CFR 258). The clay
cap shall consist of a recompacted soil barrier, a drainage layer. and a top
soil/vegetative layer.
leachate shall be extracted by a system of wells installed withiin and surrounding
the landfills (Figures 4. 5A. 58), as required for sanitary landfill closure under
RCRA, Subtitle D (40 CFR 258.61). landfill gases shall be collected by a system
of wells connected to a vacuum blower and treated using a enclosed ground flare.
The landfill gas collection and treatment system shall be constructed and operated
in accordance with state permit requirements (OAC 3745-15. 31, 35) and the
Clean Air Act. Section 101 (40 CFR 52). Ground water and landfill gas monitoring
shall also be performed to ensure the effectiveness of the containment measures.
as required for sanitary landfill closure under Ohio EPA regulations (OAC 3745-27-
12) and RCRA, Subtitle D (40 CFR 258.61).
Under Alternatives 2, 3. and 4; private homes along Zink and National Roads shall
be hooked-up to a public water supply. In addition. access restrictions. including
fencing, warning signs. and security patrols and institutional controls (i.e.. deed
restrictions) shall be utilized to limit future uses of the site.
Page 14
-------
Record of Decision: Source Control Opersble Unit - Landfills 8 and 10
i:
.//
-
~
-
o
800
I
./
,.'
FEET
EXPlANA'T1ON
------
Landfill location identified in the
Focused Remedial Investigation.
ES. 1992.
Approximate boundary of clay
cap.
Cross-section shown on F"lgure 38.
Figure 3a - Conceptual Plan Drawing of Clay Caps for landfills 8 and 1 0
Page 15
-------
A
::: ~
9,0 ~
'" 9:>0-1
~ I
"" eeo ~
~ i
~ ElISO
<>
= 840
~
~ 820
:; eoo
.\
~ 180
:: 760
'<
7'0
700
680
£60
Record of Decision: Source Control Operable Unit - Landfills 8 and 10
lANDFIll R
0:r5 fu-.C COVER --..."
I S(e oe I>ll 1
/
I. AN[\rll.l I Dr.
l"'~Of"ILl
t\::INT£NTS
",,- NEw CAP
.RUN-CH OO\(RS,QN S..Al( (IVP.)
l . I .' "'"
'\ /---"',...-...- "'.: .
~F'-EK -. ~ - «OSliN;. CO\(R
- .l, I I
\ I \ -- - OAOIMD Wda\
, I ' /'
~i.---/ L.'lA/'60
9'0
9.0
. 3;:0
. 8!O
e6e
8.0
820
800
760
760
740
70;)
6se
660
-------
Rscord of Dscision: Source Control Operable Unit - Landfills 8 and 10
- ~~t~"": ill /
. ~.~~..:. '.\ 1/1 /:
/?/\, ' '" :/ ,/
{ ~\ \:--. j .~ !( ~
,\~r\\ ~ U
r \\"0 ---~, :L
j;" FLARE I
!/
/
\
"-
""\
"
/" I:
I a J'
-,!/
,-. 1/
-~1l
~ t
,. ~J/~ c.
1-.1,. ~
' ...,
" /. I
\ .;:'~~: /' :'
// ? /
, ,-/ .I:: /
I " . I
"\ (\~..-::/ /
~~
/1
.
~ I--.t\f
,Ioe.
.. ..,........ n«L
CoA..,--c""
."
"
,","IJ'\I'2~ ,.
/"
DETAIL 1
CONa:P TuAi. PlAN or AC n"f;
LANDf'IU. CAS SYSTtIl
o
I
800
,
I
'/1.
I
FEET
EXPLANATION
~
Denotes gas extraction well location
and pipeline (location, spacing, and
number are not represented by this
depiction).
Composite site for leachate and landfill
gas treatment systems. Denotes gas
vacuum blowers, Harne arrestors,
COndensate traps and ground flares.
-
Figure 4 - Active Landfill Gas ColiectionlTreatment System for Landfills 8 and 10
Page 17
-------
Record of Decision: Source Control Operable Unit - Landfills 8 and 10
ft
/ '
: (
1/
I,
, :/
, '
I
)..
o
800
FEET
EXPlANATION
Denotes idealized location of dilute leachate
extraction wells and header.
Denotes idealized location of concentrated
leachate extraction wells and header.
-
Denotes location of leachate treatment plant
discharge.
Denotes location of leachate/landfill gas
treatment system.
Location of wells is preliminary. Final location
and number and depth of wells w;1I be
determined t7j ground-water mOdeling.
Cross-section shown on F"lQure 58.
.me
Figure SA - Preliminary Location of Leachate Collection and Treatment System
Page 18
-------
Record of Decision: Source Control Operable Unit - Landfills 8 and 70
A
~oJ l
~'c l
9~: 1
0" ~1,": 1
~ e~: ]
i) lu:"
:i !.~
.J e1~
-: !J~ ~
- ,
,; 7=~
.
~ ':'u:
.;
74G
7J:
f;'
5ee
VIrt8a8I 818C111iJ8r8'" .. IX.
---::~::::0~~:7"~~,
.
_\
.- _\
-:-:-':.
'-:::::~
\~i~
..
"
----
-~
... ~ :t
.. ."
~o~
... n'...,
oJ;:~: lANDl"lIl 8
...-
;;
"
A'
,..... 9('
~"C
:')40
. ~~c
Sc~
5eC
-
o
- .' ;;
" '..
. .. '"
~ ., 'J
. ..
~ ()'" .,
n
s
-------
Record of Decision: Source Control Operable Unit - Landfills 8 and 10
Alternative 2 - leachate Treatment Method: Metals removal. aerobic biological
treatment, and micro-pollutant removal by chemical oxidation (Figure 6).
Estimates of: Capital Cost - $10,590,000
Annual O&M Cost - $ 1,470,000
Present Worth Cost - $27,210,000
Time to Implement - 18 Months from ROD (estimate)
The leachate treatment system under Alternative 2 shall be constructed and
operated in accordance with state permit requirements (OAC 3745-15, 31, 35).
leachate flow from a number of extraction wells shall be controlled through an
equalization tank. The metals removal process shall remove heavy metals from the
waste stream (e.g., iron, copper, lead, zinc) by the addition of a caustic soda.
Aerobic biological treatment shall remove organic compounds from the waste
stream by biodegradation in an activated sludge process.
Residual organics in the leachate stream shall be destroyed by chemical oxidation.
The chemical oxidation process shall involve addition of hydrogen peroxide and
ultraviolet light to the waste stream which initiates chemical reactions that destroy
organic compounds.
Waste products formed under this alternative are: (1) sludge from the metals
removal process, (2) sludge from the biological treatment process, and (3) treated
leachate. It is anticipated that sludge from the metals removal process will be
classified as hazardous waste. As such, it will be managed and disposed in
accordance with applicable regulations (OAC 3745-52, 54, 59; and, 40 CFR 261,
262, 264, 268). Sludge from the biological treatment process will likely be
classified as non-hazardous waste and will be disposed as such.
To comply with Ohio Water Quality Standards (OAC 3745-1, ORC 6111.041), the
treated leachate shall be discharged to surface waters under a National Pollution
Discharge Elimination System permit, which meets or exceed requirements of the
Clean Water Act (40 CFR 12.44; OAC 3745-32, 33; ORC 6111.04.2).
Page 20
-------
Q
...
'tI
~
co
~
:;::
:s
~
-.J
.~
:S
.!!?
..Q
~
'II
8 ;,
... !:
g ..
c::: ....
...
8 "-
~
'II 8
~ ...
::i I
~ ~
.-
o
'. ~
c::: ~
,0 '"
~ 0
.~ ~
II>
Q q
"
... ..
0
~
0
~
8l'J~(R
A£'IJR~ A:IIV4fCO
SluO\.{
. -- -. - - -- -.
.. - -- -.. -.
- -~ .. _. - - - .- - --
-----------------
.,."'Sf( AcnV.U(O
-~
- - -- - - - -- ---
.- - -- - - - - - - "l'RA'[
ro£cA,:;----------l
I I
-.Ul :
..1
-- - - .. - - "- - -- -
(XPl ANA IICU
SiI uCC( THIC~(""4C
""'0 SIC)lIAC£
1 P'o<.'" flo. OOOIJl'Dm 00..3 ...pon
:.O~O~. ("CI'~chll.hC' OnJ ..p.c:I.J
.. 0 tUg,,",,,, "Qt.o"':11
1 "opt "'Olmeot 1"'0""" '''0-" " tn.
~:':';;:'".O'I::' I~~ e.o., I~ COq.. COt' :.,.",ot.
W[tI.lS SI..\JOC( (AM(
r~ A(~Jl4I[D OI~OS"'l
J ~::t~ O",d ""'J~' p...mp, 0" I"Iot
0" coo",
I
-@_.1
a"':""'As..
Pu..,p
8l0W{A
- -- - - - -- - - - - ,!.I~R~I~
A(RO&C I OCCAN' 1
CI~C5ICR I I
. . . I I
:::-LJ I
~i.2 . 5lUOCl ""CKCNJNC
A"O SIOAA(,(
POl "'Cft
AOOI liON
BlO1O{R
m SURf ~:(
- ~ArtA
1II000ClCAI. 5lUOCl
'0 "~-H""AADOU'S
085POSAl
E
~
>-
CI)
I
;
j ...
C\j
~ ~
t»
N Q?
.i
E
~
C&)
II
..
=
l
-------
Record of Decision: Source Control Operable Unit - Landfills 8 and 70
Alternative 3 - Leachate Treatment Method: Metals removal. aerobic biological
treatment. and micro-pollutant removal by carbon adsorption (Figure 7).
Estimates of: Capital Cost - $10,490.000
Annual O&M Cost - $ 1,630,000
Present Worth Cost - $28,940,000
Time to Implement - 18 Months from ROD (estimate)
The leachate treatment system under Alternative 3 shall be constructed and
operated in accordance with state permit requirements (OAC 3745-15, 31, 35).
Leachate flow from a number of extraction wells shall be controlled through an
equalization tank. The metals removal process shall remove heavy metals from the
waste stream (e.g.. iron, copper, lead, zinc) by the addition of a caustic soda.
Aerobic biological treatment shall remove organic compounds from the waste
stream by biodegradation in an activated sludge process.
Residual organics in the leachate stream shall be removed by carbon adsorption.
The carbon adsorption process shall include two carbon vessels operated in series.
Organic compounds adsorb to the carbon within the vessels and are removed from
the waste stream. .
Waste products formed under this alternative are: (1) sludge from the metals
removal process. (2) sludge from the biological treatment process. (3) spent
carbon. and (4) treated leachate. It is anticipated that sludge from the metals
removal process will be classified as hazardous waste. As such, it will be
managed and disposed in accordance with applicable regulations (OAC 3745-52.
54. 59; and, 40 CFR 261, 262. 264. 268). Sludge from the biological treatment
process will likely be classified as non-hazardous waste and will be disposed as
such. .
Spent carbon will be classified as hazardous waste and will be managed in
accordance with applicable regulations. It is anticipated that spent carbon will be
thermally regenerated and reused. However, if spent carbon is not acceptable for
regeneration, it will be disposed as hazardous waste in accordance with applicable
regulations.
To comply with Ohio Water Quality Standards (OAC 3745-1, ORC 6111.04.1), the
treated leachate shall be discharged to surface waters under a National Pollution
Discharge Elimination System permit, which meets or exceed requirements of the
Clean Water Act (40 CFR 12.44; OAC 3745-32, 33; ORC 6111.04.2).
Page 22
-------
C)
...
1)
~
co
~
:;::
~
~
~
....
~
~
oQ
t!!
Q)
Q.
o
'0
::i
c::
~
Q)
~
::i
JJ
r:
.S!
,~
CJ
Q)
c:a
....
C)
~
C)
~
Q::
:-~
r--~~~~-------------------l
! ~""." ~r'" !
m~~~~ I~: I-(OJ~] i n___''''''''-r------l
r- rI[D 'OA.'ST\J[N' '- ---------,-
I U'C"Ut rU"p ---- I I I
I S''''''C( I I I
I - I I I
I I
! ~':;:8 8'" ~". .".".,. ~-~
: Cl'."'C'''DN ~ r~1 r.- 1 ~.~
: ~ I' I "I : : : ------<2)- ' C
! m J~ -~f~[ :::,:. . ~\: J 1
: 0'---1 UN< -@ - ...
: ;,~o(. P'~~~SH
I ~(-~U~~~~.
I - s,ur:;(
I USI( 'c tv.ItD
I SlI'OC<-
I
: -------------------------
~---------------
I --..---
l. - -. .- - - -. - - --
[> PL ~I.A IICN
r r
I C'.PO" I
I \lS:H I
I I
I I
! L!.-
! -- ---1
--- -,
I
I
"R ""Ie
B.('o.~jSlt
".'('1
3
N
.~
flL tCAI(
------'----1
---- I C[c.., I
-(AOBlt I I
D'C(SI{. I I
I
S,,'OC( '''C«"'"< r
""0 S'O""~{ 8
POl.."tq
.A.DCI~ c....
..
- - - - - ~~..~( - - --1
------r[~:.,,, I
I I
I I
I-LJ- -'
I
w( UlS S:"JDt( (&1((
rerr Jt(~Jl"I[O Ot~CS'4.
ftC-iotA
~'
-;
,
'0 s'~r Act
""AT(R
elON[ A
-- 10 R(CUlAT{O
-2r!!.!....._- DIsPOSAl O't
CARSl" R[Cl-4A"n~
I P'oc,.. rle- tiOi"'''"' toud" "':.';:C'td
I"c; ~~' t':;'I~~;.~".':~';,~t~'
I,., ..
'lOt:" "01""',", rIClU":' '~~:: ;~ :;.,
10;' )IT'll ~:. at::,..to~~~: ;'
..1"'0 ,
, C"""'.(08 o"~ ,IJ'9' O....""CI 0" not
. ~..~.." ')of (I,..."
J
.
/
~
..
~,
/
~
,i
"
Sll'C~ 'HIC~[~ "C
""0 SIC'PAG[
8:(\l(,';1CAl Sl OOC£
- 1') N()fII-UAZ..qO!>..'S
C1SPCS"l
E
II
...
en
>
tJ)
...
C
II
E
...
III
II
...
I-
II
...
III C')
.s: ~
u
III CU
II OJ
..... ~
C")
II
>
'+:
III
C
...
II
...
Ct'
.....
II
...
:::I
CI
ii:
-------
Record of Decision: Source Control Operable Unit. Landfills 8 and 10
Alternative 4 - Leachate Treatment Method: Metals removal, aerobic biological
treatment, air stripping and carbon adsorption (Figure 8).
Estimates of: Capital Cost - $10,560,000
Annual O&M Cost - $ 1,660,000
Present Worth Cost - $29,360,000
Time to Implement - 18 Months from ROD (estimate)
The leachate treatment system under Alternative 3 shall be constructed and
operated in accordance with state permit requirements (OAC 3745-15, 31, 35).
Leachate flow from a number of extraction wells shall be controlled through an
equalization tank. The metals removal process shall remove heavy metals from the
waste stream (e.g., iron, copper, lead, zinc) by the addition of a caustic soda.
Aerobic biological treatment shall remove organic compounds from the waste
stream by biodegradation in an activated sludge process.
Residual organics in the leachate stream shall be removed by air stripping and
carbon adsorption. The process shall involve air stripping through a packed tower
followed by carbon adsorption as described in Alternative 3. Air stripping removes
volatile organic compounds (VOCs) from the waste stream by transferring the
VOCs to the vapor phase (i.e., air).
Waste products formed under this alternative are: (1) sludge from the metals
removal process, (2) sludge from the biological treatment process, (3) air emissions
from the stripping process (4) spent carbon, and (5) treated leachate. It is
anticipated that sludge from the metals removal process will be classified as
hazardous waste. As such, it will be managed and disposed in accordance with
applicable regulations (OAC 3745-59, 52, 54; and, 40 CFR 261, 262, 264, 268).
Sludge from the biological treatment process will likely be classified as non-
hazardous waste and will be disposed as such.
Air emissions from the stripping process will be discharged to the atmosphere in
accordance with state permit requirements (OAC 3745-15, 31, 35) and the Clean
Air Act, Section 101 (40 CFR 52).
Spent carbon will be classified as hazardous waste and will be managed in
accordance with applicable regulations. It is anticipated that spent carbon will be
thermally regenerated and reused. However, if spent carbon is not acceptable for
regeneration, it will be disposed as hazardous waste in accordance with applicable
regulations.
To comply with Ohio Water Quality Standards (OAC 3745-1, ORC 6111.04.1), the
treated leachate shall be discharged to surface waters under a National Pollution
Discharge Elimination System permit, which meets or exceed requirements of the
Clean Water Act (40 CFR 12.44; OAC 3745-32, 33; ORC 6111.04.2).
Page 24
-------
C)
....
13
c::
~
0::»
~
:;::
~
c::
~
.....
,~
:5
-S!
.Q
~ "
CD
~ :
-
g ~
~
c:: 'f.
~
CD
~ c
::i /
<>
~ 'i
'-'
'. ~
c:: ~
,~
,~ ~
~
Q
....
()
~
()
~
B.(..;.nSH
r---- ----- ---- - ------- - - ---- -,
i ~ """" ~ '. 0" i
~~IC-;;;;-t1J. i ~ 1111~~!:L i
!.'S'(W I
r '([D A.f:IAJ;~["'f 'lOCCVlAnOt-f I
: LE"CU41t PUUP I IACK'IUSH
I S'''''AU; ---- L.-----'-------------------r------l
I I o<'-C'5 I I
: : I I
: s""~~:~~ 8~j~t. I I I
! a.'."CA"O'< Jf~ I [C\"'"C''''''' I CAReoo< f
I ~Lru 1 I~ssn I
I : : : I I
: " 1--- ill - HID::
I ~ [ PU"" I I
: -. ~- AI~.~::O" . J ::
I .Jt.:.1 ~- I ---
I Bl~' ---.& L.- - -.- --.1
I 8.~~.~il~SH I
i -1 .I'l'~:,~~;"'ID .'Sl[ """'10 .:~h~"
I ~uo~
I rlL 1AA ~(
[~~ ~~ ~=~ ~~= =~: ~ ~ ~ ~ ~~ = = =~=.~ = ::= =;~~~[==~=~ -- -- --;.;;~---- -f[;'~--l
(.qAlUI'ON L I C[C"" I ~.: : : I
---- I ::: U
~':r;~~:I" rl~:O'C~~~~~;:.O';"d~ ~:'~'t'fd U: 'I PLAt[ AH~: . 8.Jz .-
1,_,1 0' "Iot....,.., ":)J:',d - -- rAU/[ PRtSS .-'
. SLl'OG( lHC.(~'I/~
IJOp" "f)'''''''"' I"::IU"" '''('.'' ... ,.... ',t.t.I() S10fU.C(
cJ.o~'o'" _(r, I". tlo~' 'or CJR.. CO'1
..lilT-"l lor AII,'n,I,., 4 SIU;,~ ;~~~~ N:; Bl(t.{SI
"I hU -KuOf.c (AI((
rcq ACC'JlAI(O OISP~SA.l
~ :,.,,..,.'c01 0100 ''''''9' p"......,. CJl't lOt'I
,.."." '01 ('0'.1,
rQl1'\l(1Ii
"C~.,,()I.I
E
GI
...
1/1
>-
CI)
...
C
GI
E
...
IV
GI
...
....
GI
JO 5~r Act ...
.....ItR IV 10
..c
o ~
IV
'+:;
IV
C
...
GI
...
-------
Record of Decision: Source Control Operable Unit - Landfills 8 and 10
H.
Summary of the Comparative Analysis of Alternatives
NINE EVALUATION CRITERIA
,. Overall Protection of Human Health and the Environment: addresses whether on not
a remedy provides adequate protection and describes how risks are eliminated, reduced,
or controlled.
2. Compliance with Applicable or Relevant and Appropriate Requirements (ARARs):
addresses whether or not a remedy will meet all federal, state, and local environmental
laws and/or regulations.
3. long-Term Effectiveness and Permanence: refers to the ability of a remedy to
provide reliable protection of human health and the environment over time.
4. Reduction of Toxicity, Mobility, or Volume through Treatment: refers to the
preference for a remedy that reduces health hazards, movement of contaminants, and
the Quantity of contaminants at a site.
5. Short-Term Effectiveness: addresses the period of time needed to complete the
remedy, and any adverse effects to human health and the environment that may be
caused during the construction and implementation of the remedy.
6. Implementability: refers to the technical and administrative feasibility of a remedy,
including the availability of materials and services needed to carry out a remedy and the
ability to coordinate federal, state, and local regulatory requirements.
7. Cost: compares the estimated capital, operation and maintenance, and net present
worth costs associated with each alternative.
8. Support Agency Acceptance: refers to whether the USEPA and the Ohio EPA agree
with, oppose, or have no comment on the alternative.
9. Community Acceptance: addresses whether interested persons in the community
are likely to support, have reservations about, or oppose the alternative. This
assessment may not be completed until public comments on the Proposed Plan are
received.
1. Overall Protection of Human Health and the Environment
Alternative 2, 3, and 4 are protective of human health and the environment. Human and
environmental contact with landfill contents, contaminated soils and leachate is prevented by
construction of clay caps. Active landfill gas control eliminates explosion, fire, and
inhalation risks associated with landfill gases. Continued contamination of groundwater and
Page 26
-------
Record of Decision: Source Control Operable Unit. Landfills 8 and 10
other risks associated with the generation and spread of leachate is reduced by the clay cap
and leachate collection and treatment measures and conversion of private well users to public
water supplies.
2. ComDliance with ADplicable or Relevant and ApproDriate Requirements (ARARs)
Alternatives 2, 3, and 4 are expected to comply with all ARARs. The clay cap will be
constructed and maintained in compliance with Ohio EPA regulations for sanitary landfill
closure, which meet or exceed requirements of RCRA, Subtitle D.
A system to collect and treat leachate, as required under RCRA, Subtitle D, will be
constructed and operated to meet state permit requirements. All waste products from the
leachate treatment processes will meet applicable management and disposal regulations,
including the discharge of treated leachate to surface waters which will comply with Ohio
Water Quality Standards and the Clean Water Act under a National Pollution Discharge
Elimination System permit.
A system to collect and treat landfill gas will be constructed and operated to meet state
permit requirements and the Clean Air Act, Section 101. Ground water and landfill gas
monitoring will also be performed to ensure the effectiveness of the containment measures,
as required for sanitary landfill closure under Ohio EPA regulations and RCRA, Subtitle D.
3. Lone- Tenn Effectiveness and Pennanence
A low permeability clay cap is a common and effective technology used to close landfills. It
is designed to reduce or eliminate exposure by isolating landfill contents. Further, a clay cap
helps prevent rainwater infiltration and erosion which contributes to the spreading of
contaminants. Alternatives 2, 3, and 4 are expected to be equally effective at isolating
landfill contents and are expected to reduce by 70% leachate generated by infiltration of
rainwater. Leachate generated by the flow of ground water through landfill contents will be
captured by the leachate collection system. The effectiveness of the capture will be
determined through monitoring.
Replacing private water sources with a public water supply will provide a permanent solution
to potential risks associated with ground water contamination.
Alternatives 2, 3, and 4 will leave landfill contents in place. Therefore, the long-term
effectiveness and permanence of the alternatives relies on proper maintenance of the clay cap
and collection and treatment systems. Alternatives 2 and 4 require the highest level of
mechanical maintenance due to the associated chemical oxidation and air stripping systems.
Since hazardous waste will remain on-site under all three alternatives, overall effectiveness of
the selected alternative in meeting the clean-up goals of SCOU will be reviewed at least
every five years.
Page 27
-------
RBCord of DBCision: Source Control Operable Unit - Landfills 8 and 10
4. Reduction of Toxicitv. Mobilitv. or Volume throU2h Treatment
The primary objective of this remedy is containment of contaminants emanating from
Landfills 8 and 10, as such treatment is not a principal component. There is reduction of
Toxicity, Mobility, and Volume (TMV), but it is treatment of residuals inherent in the
containment alternative.
Alternatives 2, 3, and 4 provide equal reductions of TMV. In general, all three alternatives
remove leachate contaminants by 90-100%. The chemicals of concern removed through
leachate treatment are estimated as follows.
APPROXIMATE ANNUAL REMOVAL
CONTAMINANT
CLASS ALT. 2 ALT. 3 ALT. 4
Organics 99 Ib/yr 1 06 Ib/yr 108 Ib/yr
Metals 13,500 Ib/yr 13,500 Ib/yr 13,500 Ib/yr
Ammonia 792 Ib/yr 792 Ib/yr 796 Ib/yr
Table 4: Annual Removal Rates for the Chemicals of Concern
Organics in the leachate will be largely destroyed in the biological treatment process. Air
stripping under Alternative 4 provides no significant removals due to the near complete
removal of volatile organics in the biological treatment process. The toxicity and mobility of
metallic contaminants in the leachate will be reduced in the metals removal process.
Alternative 2 destroys residual organic contaminants in leachate through chemical oxidation;
whereas, Alternative 3 transfers residual organics to carbon, and Alternative 4 transfers
residual organics to air and carbon. However, since Alternatives 3 and 4 include thermal
regeneration of carbon, the residual organics are destroyed.
Organic contaminants removed via gas collection will be destroyed by approximately 97%
through treatment. The amount of volatile organic chemicals of concern destroyed through
gas collection and treatment will be approximately 1,000 pounds per year.
5. Short- Tenn Effectiveness
Alternatives 2, 3, and 4 include installation of clay caps which, during construction, will
increase dust emissions from the site. However, airborne particulates, to date, have not
shown any chemical contamination.
Page 28
-------
Record of Decision: Source Control Operable Unit - Landfills 8 and 10
General construction and operation activities associated with Alternatives 2, 3, and 4 could
expose workers to landfill contents, gases, and/or leachates. All three alternatives also pose
risks associated with handling feed materials and residuals from the leachate treatment
system. The leachate treatment system associated with Alternative 2 poses additional risks
from the handling of chemical oxidants.
Strict health and safety standards and engineering controls are effective in reducing or
eliminating risks to workers and the community during construction and operation. The
necessary controls will be identified in health and safety plans for construction and operation.
6. ImDlementability
All technologies employed by Alternatives 2, 3, and 4 are proven, and the services and
materials needed to implement the alternatives are available. However, a broader spectrum
of suppliers and operators exists for carbon adsorption.
Under state law, permits will be required to: (1) install and operate the leachate and landfill
gas collection systems, and (2) discharge treated leachate and treated gases.
7. Cost
The net present worth cost of Alternative 3 is $30.4 million (20 years @ 6%). This is 6.0%
more costly that Alternative 2 and 1.4 % less costly that Alternative 4. The highest cost
items are construction of the clay cap and leachate collection system and operation of the
leachate treatment system.
Alternative 2
Alternatve 3
Alternative 4
Capital Costs
10.808,000 10,798,000 10,865,000 .
1,520,000 1.730,000 1,760,000
28.024,523 30,423,200 30,834,299
o and M Costs
Total Costs
Table 5: Cost Comparison for Alternatives
Page 29
-------
Record of Decision: Source Control Operable Unit - Landfills 8 and 70
8. Aeencv Acceptance
Under the Administrative Orden~-on Consent (Feb 1988) and the Federal Facility Agreement
(Mar 1991), Ohio EPA and USEPA Region V, respectively, must concur with the final
remedial alternative. WPAFB, as the lead agency for the SCaD, fully coordinated all
investigations and clean-up activities with both Ohio EPA and USEPA Region V. As a
result, both agencies support the selection of Alternative 3. Agency acceptance of any
alternative includes obtaining applicable permits to install and operate the remedy.
9. Communitv Acceptance
This criteria indicates whether the public concurs with, opposes or has no comment on the
preferred alternative. During the public meeting and comment period the main concerns of
the public were the length of time for investigation and cleanup, containment methods, and
health hazards posed by the landfills.
Section III contains the Responsiveness Summary from the public meeting and public
comment period.
Page 30
-------
Record of Decision: Source Control Operable Unit - Landfills 8 and 10
I.
The Selected Remedy
The Air Force, OEPA and USgPA have selected Alternative 3 as the remedy for the Source
Control Operable Unit for Landfills 8 and 10, Wright-Patterson AFB. Alternative 3 was
found to provide the best balance of trade-offs when evaluated against the nine criteria
described above.
Alternative 3 includes:
.
Access restrictions.
.
Deed restrictions.
.
Clay cap on landfills 8 and 10.
.
Active landfill gas control and treatment.
.
Active leachate collection.
.
leachate treatment using equalization, metals precipitation,
biological treatment, filtration, carbon adsorption, and reaeration.
.
Discharge of treated effluent to an on-site surface water.
.
Provision of public water supply.
.
Air, explosive gas, and groundwater monitoring.
.
Operation and Maintenance of Remedy
The overall goal of the SCOU for remedial response actions at Landfill 8 and 10 is to protect
human health and the environment. In addition, the remedial response actions will permit
continued residential land use. The principal media and general remedial action objectives
(RAO) for the SCOD are as follows:
Soil/Landfill Contents--To prevent direct contact with and dermal absorption and
ingestion of the contaminated soils and landfill contents; control surface water runoff,
ponding, and erosion; to prevent or reduce infiltration and production of leachate; and
Page 31
-------
R8Cord of Decision: Source Control Operable Unit - Landfills 8 and 10
to control dust emissions to meet ambient air exposure criteria.
Landfill Gas-- To prevent inhalation of gases and the potential for explosion by
controlling landfill gases, and to meet ambient air exposure criteria.
Leachate/Leachate Seeps-- To prevent contaminants of interest in leachate from
migrating to surface waters and ground waters; to prevent dermal absorption and
ingestion of this leachate; and to reduce/eliminate on-site leachate generation.
Private Wells (Ground Water)--To prevent ingestion, dermal absorption, and
inhalation of contaminants.
The selected remedy will achieve these RAOs as follows:
Institutional Controls:
Deed restrictions: Deed restrictions will be implemented to restrict future use. Landfill 8
and 10 are included in a deed. Deed restrictions must prohibit construction, mining, drilling,
installation of wells and other activities which shall interfere with the remedy or allow
humans to come into contact with the contamination on-site. Restrictions shall be filed with
the deed not later than 15 months from the effective date of the ROD. If and when the
property is transferred, these restrictions will be put on the deed, and all other requirements
for property transfer under CERCLA Section 120 and CERFA shall be followed.
Access restrictions: WP AFB desires to return much of the area to recreational use
ultimately. However, in order to ensure the remedy is protective of human health, access
restrictions will be maintained around the landfills. Once it is determined that the landfills
are not a threat to human health and the environment, access restrictions will be limited to
the operational aspects of the remedy, including the collection and treatment systems.
Access restrictions include fencing, posted warnings, and security patrols.
Eneineerim~ Controls:
Containment: Clay caps will be provided for both Landfills 8 and 10. A clay cap will:
. minimize downward percolation of precipitation thereby reducing the production of
concentrated leachate in both Landfills 8 and 10. However Landfill 8 will continue to
produce dilute leachate because of the flow of ground water through that landfill;
. minimize fugitive gas emissions;
. reduce off-site contamination from dust;
. prevent erosion; and
Page 32
-------
Record of Decision: Source Control Operable Unit - Landfills 8 and 10
. prevent direct contact.
As the landfill cap takes effect and landfill materials dewater to some extent, the amount of
leachate requiring treatment should decrease over time. The cap will reduce the flow of both
concentrated and dilute leachates.
A plan and cross-section drawing of the clay cap is shown in Figures 3A and 3B,
respectively. After capping, the landfill will be revegetated and could be returned to
recreational use.
The existing partial cap on Landfill 10 is not compatible with the overall design requirements
of the landfill cap. It will be destroyed in-place and covered with the new landfill cap to
preclude unwanted and uncontrolled pathways from remaining.
Installation of the new landfill caps will have to take into consideration the future installation
of the concentrated leachate collection system and the landfill gas collection system. Once
the cap is in place, it shall be disturbed as little as possible.
Active Landfill Gas Collection and Treatment: Gas generation for Landfills 8 and 10 was
estimated to be 68 cubic feet per minute (CFM) based upon a refuse density of 1,100 Ib/y&
and a unit gas generation rate of 180 ff/ton/yr. The waste gas generation rate was estimated
from values reported in the literature. For design purpose, a value of 150 standard cubic
feet per minute (SCFM) will be used to account for seasonal variation and other factors such
as refuse composition, moisture and pH, etc.
The gas collection system shall be designed to meet the remediation goals for landfill gas and
for compatibility with the clay cap and leachate collection systems. Gas collection wells,
vents or layers will intercept the landfill gas moving off-site and minimize venting vertically
to the atmosphere. A conceptual plan that depicts landfill gas collection by a well system is
shown in Figure 4.
The gas shall be discharged to an enclosed ground flare designed for the volume and
character of collected gases.
Leachate Collection: Calculations provided in Section 3 and in Appendix C of the SCaD
Focused Feasibility Study suggest that (including safety factors) a maximum of 46 gallons per
minute (gpm) of leachate could be extracted using an active leachate collection system. A
series of leachate extraction wells will be installed within and surrounding both Landfills 8
and 10. The well system will be designated to pump the leachate to an elevated equalization
tank from which a regulated, continuous flow could be delivered to the leachate treatment
system serving both landfills.
Leachate Treatment: The leachate treatment system will consist of a metals removal
process followed by a packaged biological (activated sludge) wastewater treatment plant.
Residual non biodegradable organics will be destroyed with carbon adsorption. Figure 7 is a
Page 33
-------
Record of Decision: Source Control Operable Unit - Landfills 8 and 10
process flow diagram of the leachate treatment system.
Equalization: The equalization tank will provide retention time to equalize the flow and
strength from the concentrated and dilute leachate extractions systems. This tank is
necessary to provide continuous operation of the treatment system and proper performance of
the activated sludge system.
Metals Precipitation: The metals removal process will remove metals as hydroxide
precipitates. Significant amounts of iron and manganese will be removed in this process.
Other metals that form insoluble hydroxide precipitates are present in such low
concentrations that little, if any, will be removed in this system.
The metals removal process will consist of metals precipitation with the addition of a
coagulant followed by flocculation and clarification. Engineering studies will be required to
determine the use of caustic or lime in terms of effectiveness for metals removal and
dewaterability of the sludge. Enough caustic will be added to raise the pH for metals
removal.
Aerobic Biological Treatment: The activated sludge process will remove biodegradable
organics (measured by the BOD and COD tests). Volatile organics will also be removed by
biodegradation.
The activated sludge effluent will be filtered through a granular media filter to remove
suspended BOD and if present, heavy metals precipitates. Sludge generated from the aerobic
biological treatment system, if hazardous, must be disposed of in accordance with USEPA's
Off-Site Policy.
Filtration: Granular media filtration placed downstream of the activated sludge process
will remove biological solids, other organics, and some metal precipitates, if present, from
the activated sludge effluent.
Activated Carbon: Activated carbon adsorption will be used to remove the non-
biodegradable organics as an effluent polishing process. The carbon system will remove
significant quantities (on a percentage basis) of the individual organic chemical species which
remain following activated sludge treatment. In addition this system will remove a
significant percentage of COD remaining (75% estimated) and of the remaining BOD (40%
estimated). The removal of these unidentified organics which comprise the bulk of the COD
will reduce the toxicity of the effluent.
Reaeration: Effluent reaeration will also be required to meet the receiving stream
dissolved oxygen standard.
Ion Exchange: Ion exchange is retained as a contingent option in case field monitoring
data indicate the need for this process to comply with surface water discharge requirements.
The ion exchange system will be located downstream from the carbon adsorption system and
Page 34
-------
Record of Decision: Source Control Operable Unit - Landfills 8 and 70
will be employed to remove residual metals if permit limitations cannot be achieved
otherwise.
Surface Water Discharge: Effluent from the leachate treatment system will be discharged
to the unnamed tributary to Hebble Creek which flows between Landfills 8 and 10. The
discharge will require an NPDES permit from OEPA and will be required to meet permit
limits.
Ground Water and Ambient Air Monitoring: The selected remedy also includes both
ground water and ambient air monitoring. Ground water monitoring is required by state and
federal regulations as part of a landfill closure. The number and location of compliance
monitoring wells shall be determined during design, and approved by USEPA and OEPA.
Public Water Supply: Under this alternative, hookup to a public water supply, either from
WPAFB or the City of Fairborn, will be provided to homes along National and Zink Roads
that use private wells for drinking water.
Observational Approach: It is the intent of WP AFB to proceed as expeditiously as
practicable in the implementation of the selected remedy with community and regulatory
agencies' inputs. To maintain this current emphasis, WPAFB and the regulatory agencies
will adopt an observational approach to continue the preparation of the subsequent remedial
design and remedial action activities. The purpose of the observational approach is to
implement as quickly as possible the selected remedy to provide long-term and cost-effective
facilities which include permanent and ARAR-compliant remedies that afford protection to
the community and the environment.
The observational approach to site remedial design/remedial action includes four key
elements:
Remedial design using all available data;
Identification of expected operating conditions for the extraction and treatment systems
(leachate and landfIll gas) including the ranges of variations in flow rates and in the
chemical composition of the influent and effluent that the selected system, as designed,
will be able to accommodate;
Identification of key monitoring parameters, such as treatment system influent and
effluent composition, leachate extraction flow rates, and water level and chemical
composition data of selected monitoring wells to verify the effectiveness of leachate
contamination capture and treatment system effectiveness; and
Development of contingency plans to address variations from the leachate extraction and
treatment system's expected range of operating conditions.
The application of this observational approach to source control remedial actions for
Landfills 8 and 10 will be necessary for some limited design investigations. The limited
design investigations required include:
Page 35
-------
Rscord of Decision: Source Control Operable Unit - Landfills 8 and 10
Field pumpine tests. Field pumping tests shall be performed to more accurately define
radii of influences, pumping rates, screening intervals, pump sizes, operational controls
(for intermittent operation) and other operational planning and design data.
Slug Testing. To evaluate the hydraulic conductivity of the landfill materials and
potential pumping rates, slug tests will be performed on selected existing Landfills 8 and
10 leachate wells.
Gas Sampling. Samples of the landfill gas shall be collected and analyzed to determine
the heat value of the gas. This information is needed for design of the ground flare
burner and to determine the capacity of supplemental fuel storage required.
Once the landfill cap is installed and the gas leachate collection systems are in operation, the
effects of these installations, in terms of landfill subsidence, water table levels and leachate
generation rates shall be monitored and documented.
Cost of ImDlementation: The estimated capital, operational, and present-worth costs
associated with the selected remedy are shown in Table 6 based on 20 years of operation, at
a 6% interest rate, the remedy will cost $30,423,202.00.
Under this alternative, the highest single cost item will be the clay cap. The next highest
costs will be associated with construction and operation of active leachate collection and
leachate treatment technologies with off-site disposal of residuals.
Page 36
-------
Record of Decision: Source Control Operable Unit - Landfills 8 and 10
Landfill 8 Landfill 10 Landfills 8 and 10 Subtotals
Item Capital $ O&M $ Capitel $ O&M $ Capital O&M 11-5 yr) O&M 1>5 yr)
$Iyr $/yr $/yr
Deed Restrictions 1,200 0 0
Fencing and Posted 81,000 0 0
Warnings
Security 0 59,000 59.000
Clay Caps 2,500,000 32,000 1 ,900,000 29,000 4,400,00 61,000 61,000
o
Post-Closure Ground- 0 85,000 0 85,000 0 170,000
Water Monitoring 170,000
LFG Control System
Extraction Wells 230,000 21 ,000 150,000 20.000 380.000 41 ,000 41 .000
Enclosed Ground 94,000 350
Flares 350
LFG Collection 26,390 1,320 26,390 1,320 52,780
Transfer Piping 2,640 2,640
Monitoring
Ambient Air 0 103.790 103.790
Explosive Gas 50,000 59,280 29,640
Leachate Collection
System
Extraction Wells- 572,545 57,255 596,075 56.608 1,168,62 116,863 116,863
Concentrated 0
Extraction Wells- 450,000 150.000 600,000 200,000 1,050,00 350.000 350.000
Dilute 0
Pipelines and Dilute
Leachate Collection 340.000 3.700 3,700
Headers
Leachate Treatment .
Metals Pracipitation 1,400,00 235,740 235.740
o
Biological Treatment ' 920,000 110,000 110,000
GAC 230.000 350.000 350,000
Laboratory Testing 0 48.620 48,620
Access Road to 21.000 0 0
Treatment Plant
Off-Site RCRA Landfill
Sludge Disposal- 0 8,000 8,000
chemical ..,; "
Transportation 0 2.900 2.900
Off-Site Solid Waste ',':'>'::::' "",
Landfill
Sludge Disposa" 0 550 550
biological
Transportation ' .., ,. 0 1.100 1.100
Surlace Water Discharge 9.515 66 66
Public Water Supply 260.000 2,600 340.000 2.600 600.000 5.200 5,200
TOTAL 10.798,115 1.729.799 1.700.168
TOTAL REMEDY COST .30.423.202
Table 6: Summary of Remedy Costs
Page 37
-------
Record of Decision: Source Control Operable Unit - Landfills 8 and 10
Perfonnance Standards: Table 7 presents performance standards for the selected remedy-
Permit Based Performance Standards
Leachate Treatment System: The performance standards for the leachate treatment standards
will be established by the Ohio National Pollution Discharge Elimination System (NPDES) Permit
to Operate.
Landfill Gas Treatment: The landfill gas treatment system performance standards will be based
on the Air Discharge Permit to Operate.
Ambient Air Monitoring: Ambient Air Monitoring performance standards will be based on the Air
Discharge Permit to Operate.
Other Performance Standards
Clay Cap Performance Standards: To meet the requirements of Ohio Administrative Code (OAC)
3745-27-11 for closure as a solid waste landfill, the cap will be constructed to include at a
minimum:
. a recompacted soil barrier layer with a minimum 2 feet thickness and with a maximum
permeability of 1 x 10-7 cm/sec.
. a drainage layer with a minimum 1 foot thickness and a minimum permeability of 1 x 10-
3 cm/sec.
. a vegetative layer consisting of soil and vegetation, 3 foot thick
. minimum slope of 5% and a maximum slope of 25%
. The cap system will be designed to have a maximum projected erosion rate of five tons
per acre per year.
Methane Monitoring: Methane monitoring performance standards will be the OAC 3745-27-12.
Leachate Collection System: The leachate collection system shall establish a capture zone that
extends outside of the landfill boundaries as determined by groundwater level measurements,
such that migration of leachate beyond the landfill boundaries is eliminated.
Groundwater Monitoring: Groundwater beyond the landfill boundaries will be monitored for
exceedences of the MCLs, or PRGs where MCLs where not available, for the chemical of
concern.
Landfill Gas Collection: The landfill gas collection system shall establish a capture zone that
extends outside of the landfill boundaries as determined by methane gas measurements, such
that migration of methane beyond the landfill boundaries is eliminated.
Table 7: Performance Standards for the Selected Remedy
Performance levels for the selected remedy will be established for the treatment plants based
on permit requirements. The performance standards for the leachate treatment system will
be established by the Ohio National Pollution Discharge Elimination System permit to
operate. The landfill gas treatment system performance standards will be established by the
Air Permit to Operate.
Compliance Levels: Compliance Levels establish acceptable exposure levels that are
protective of human health and the environment. Table 8 presents the Compliance Levels for
the SCOU. In determining this list, a residential land-use scenario was used. This scenario
assumed that the primary risks were due to direct ingestion of soil and water and inhalation
of volatile organic compounds (VOCs) from household water use. Also, the highest
concentration found among all samples collected was used. For soils, risk-based
Page 38
-------
Record of Decision: Source Control Operable Unit - Landfills 8 and 10
(J
concentration levels were calculated and used to develop the list of chemicals. For water,
both risk-based concentration levels and maximum contaminant levels (MCLs), or non-zero
maximum contaminant level goals (MCLGs) from the Safe Drinking Water Act (SDW A),
were used because of the assumption of direct ingestion.
Points of Compliance: Points of compliance for subsurface gas migration, leachate
migration, and ambient air monitoring are the boundaries of the landfill.
System Shut-Off Criteria: Shut-off criteria for the leachate collection and treatment system
will be one year's groundwater monitoring where no compliance levels are exceeded by the
chemicals of concern. Compliance monitoring shall continue during any extended periods of
shut-off.
Manal!ement of Residuals:
Metals Precipitation. The chemical sludge production is estimated to be 20 cu. yd.lyear
after dewatering to 30% solids. The metals sludge may be hazardous and therefore shall
require disposal in a RCRA-permitted facility in accordance with the land disposal
restrictions.
Aerobic Biological Treatment. The biological sludge produced by the treatment process
may pass TCLP analyses and be classified as a non-hazardous waste. This determination
will be made based on analysis of the first batch.
Activated Carbon. Carbon usage is estimated at approximately 200,000 lb/year which
corresponds to a loading rate of approximately 10 grams of GAC per gram of TOC. The
200,000 lb/year of spent carbon shall have to be regenerated or disposed of at a RCRA-
permitted facility. Typically, carbon suppliers provide regeneration services at their off-site
facilities.
Ion Exchange. Included with the ion exchange system shall be a system to concentrate and
treat the brine produced from regenerating the ion exchange resins. Should regeneration be
infrequent, disposal of the brine at a RCRA-permitted facility may be considered.
All wastes generated during implementation of the remedy shall be handled in compliance
with OSWER Directive 9330.2-07, Notification of Out-Of-State Shipment of Superfund
Wastes.
Page 39
-------
Record of Decision: Source Control Operable Unit - Landfills 8 and 10
Chemlc81. of Concern W8ter lug/L) Soli lug/Ll
Benzene 0.62
Chloroform 0.28
1.2.Dichloroetheneltl 6.77x10.2
2.3.7.8. TCDD 5.67x10-7 4.27x10.6
Methylene Chloride 6.22
N8phth81ene NA
Toluene NA
T richloroethene 3.03
Vinyl Chloride 2.83x10-2
Ethyl Benzene NA
1.2.3.4.6.7.8 HPCDF 5.67x10-5
4-Methylphenol NA
Diethylphth818te NA
Arachlar 1 242 8.31x10-2
Arochlor 1 248 8.31x10-2
Arachlor 1254 8.31x10-2
Arachlar 1260 8.31x10-2
Benza(8)pyrene 5.57x10.2
Dieldrin 4.00x10.2
1.2.3.4.6.7.8 HPCDD 5.67x10-5
1.2.3.4.6.7.8.9 OCDD 5.67x10-4
2.3.7.8 TCDF 5.67x10-6
1.2.3.4.6.7.8 HXCDD 5.67x10-6
1.2.3.4.6.7.8.9 OCDF 5.67x10-4
Arsenic 11.0
Beryllium 0.02 0.149
C8dmium NA
Copper NA
Iron NA
Le8d NA
Zinc NA
CY8nide NA
Ammani8 NA
Table 8: Compliance Levels for the Chemical of Concern
Page 40
-------
Record of Decision: Source Control Operable Unit - Landfills 8 and 10
K. Statutory Detennination
Under its legal authorities, WPAFB's primary responsibility at this NPL site is to undertake
remedial actions that achieve 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 must comply with ARARs
unless a statutory waiver is justified. The selected remedy must also be cost effective and
utilize permanent solutions and alternative treatment technologies or resource recovery
technologies to the maximum extent practicable. Finally, the statute expresses a preference
for remedies which significantly reduce the volume, toxicity, or mobility of hazardous waste.
The selected remedy will satisfy all the statutory requirements without the need to
compromise any criteria.
Protection of Human Health and the Environment. The remedial action will prevent
direct contact with on-site contaminants and prevent on-site contamination from spreading.
Human and environmental contact with landfill contents, contaminated soils and leachate is
prevented by construction of clay caps. Active landfill gas control eliminates explosion, fire,
and inhalation risks associated with landfill gases. Continued contamination of groundwater
and other risks associated with the generation and spread of leachate will be reduced by
leachate collection and treatment measures and conversion of private well users to public
water supplies.
Compliance with ARARs. The elements of the selected remedy will all comply with the
ARARs established for the site. The ARARs include:
LOCATION-SPECIFIC ARARs:
There are no location specific ARARs
ACTION-SPECIFIC ARARs:
OAC 3745-27-11
Final Closure of Sanitary Landfills.
This remedy involves the capping of a landfill which was closed prior to promulgation of these
requirements; therefore the substantive requirements of OAC 3745-27-11 ar relevant and appropriate.
Furthermore, these requirements are more stringent than the requirements contained in 40 CFR
258.60, Criteria for Municipal Solid Waste Landfills - Closure Requirements.
OAC 3745-27-14
40 CFR 258.61
Post-closure Care of Sanitary Landfills.
Criteria for Municipal Solid Waste Landfills - Post Closure Care Requirements.
This remedy involves the capping of a landfill which was closed prior to promulgation of these
requirements; therefore the substantive requirements of OAC 3745-27-14 are relevant and appropriate.
OAC 3745-17-08
Restrictions on Emission of Fugitive Dust.
This remedy is not located within an area regulated by this requirement. However, because of the
close proximity of the site to private homes, the technical requirements of OAC 3745-17-08 are
relevant and appropriate.
Page 4 1
-------
Record of Decision: Source Control Operable Unit - Landfills 8 and 10
OAC 3745-38
40 CFR 122
Ohio NPDES General Permits.
National Pollution Discharge Elimination System.
40 CFR 122 and OAC 3745-38 reQuire a general construction permit and best management practices
for erosion and storm water runoff controls be implemented at sites where over five acres will be
affected. Since this remedy involves capping over 5 acres of landfill, these reQuirements are
applicable.
OAC 3745-31
Permits to Install New Sources.
These reQuirements are applicable to the modification of solid waste disposal facilities. Under the NCP,
remedial activities occurring on-site must meet substantive but not administrative reQuirements.
However, under Section 9B of the Administrative Orders of Consent between OEPA and WPAFB,
permits are reQuired for Remedial Activities.
OAC 3745-35
Air Permits to Operate and Variances.
These requirements are applicable to the modification of solid waste disposal facilities. Under the NCP,
remedial activities occurring on-site must meet substantive but not administrative reQuirements.
However, under Section 9B of the Administrative Orders of Consent between OEPA and WPAFB,
permits are required for Remedial Activities. Finally the reQuirements of OAC 3745-35 encompass all
requirements stated in the Clean Air Act Section 101,40 CFR 52, and OAC 3745-15-07 which are
germane to this remedy.
OAC 3745-52
OAC 3745-54
40 CFR 264
40 CFR 262
Standards for Generators of Hazardous Waste.
Management of Hazardous Waste.
Standards for Owners and Operators of Hazardous Waste Treatment, Storage and
Disposal Facilities.
Subpart I - Use and Management of Containers.
Subpart J - Tank Systems.
Standards Applicable to Generators of Hazardous Waste.
These standards are applicable to the hazardous waste determination and its subseQuent management.
40 CFR 261.24
40 CFR 268
OAC 3745-59
Identification and Listing of Hazardous Materials - Toxicity Characteristics.
Subpart D: land Disposal Restrictions - Treatment Standards.
Hazardous Waste Restricted from land Disposal - Exception.
These reQuirements are applicable to the determination of the toxicity of sludge produced by the
leachate treatment system and its subsequent disposal.
40 CFR 125
Criteria and Standards for the National Pollution Discharge Elimination System.
Best Available Technology (BAT) requirements for treatment of toxics is applicable to the leachate
treatment systems since it involves a point-source discharge to a surface water.
40 CFR 122.44
ORC 6111.04.2
National Pollution Discharge Elimination System - Establish limitations, Standards,
and Other Permit Conditions.
Regulations Requiring Compliance With National Effluent Standards.
These reQuirements are applicable to point-source discharges to surface waters. This remedy involves
an on-site discharge to surface waters. Under the NCP, remedial activities occurring on-site must meet
substantive but not administrative reQuirements. However, under Section 9B of the Administrative
Orders of Consent between OEPA and WPAFB, permits are reQuired for Remedial Activities.
Page 42
-------
Record of Decision: Source Control Operable Unit - Landfills 8 and 10
OAC 3745-32-02
OAC 3745-33-02
OAC 3745-33-02
OAC 3745-33-02
Section 401 Water Quality Certification Required.
Ohio NPDES Permits Required.
Ohio NPDES Permits - General Permit Conditions.
Ohio NPDES Permits - Criteria for Issuing Permits.
These requirements are applicable to point-source discharges to surface waters. This remedy involves
an on-site discharge to surface waters. Under the NCP. remedial activities occurring on-site must meet
substantive but not administrative requirements. However, under Section 9B of the Administrative
Orders of Consent between OEPA and WPAFB, permits are required for Remedial Activities.
OAC 3745-27-10
Ground Water Monitoring Program.
This remedy involves the capping of a landfill which was closed prior to promulgation of these
requirements; therefore the substantive requirements of GAC 3745-27-1 0 are relevant and appropriate.
OAC 3745-27-12
ORC 3734.04.01
Explosive Gas Monitoring
Explosive Gas Monitoring Plan for Sanitary landfill; Evaluation 01 Threat;
Abatement Order; Inspections; Rules.
This remedy involves the capping of a landfill which was closed prior to promulgation of these
requirements; therefore the substantive requirements of GAC 3745-27-12 and GAC 3734-04-01 are
relevant and appropriate.
CHEMICAL SPECIFIC ARARs:
OAC 3745-'
Water Quality Standards
These requirements are applicable, since the remedy involves a point-source discharge to a surface
water.
Cost Effectiveness. The selected remedy is cost effective in mitigating the principal risk posed
direct contact with on-site contaminants and their spread off-site. Section 300.430(f)(ii)(D) of
the NCP requires an evaluation of cost-effectiveness by comparing all the alternatives which
meet the threshold criteria: protection of human health and the environment and compliance with
ARARs, against three additional balancing criteria: long-term effectiveness and permanence,
reduction of toxicity, mobility or volume through treatment, and short-term effectiveness. The
selected remedy meets these criteria and provides for overall effectiveness in proportion to its
cost. The estimated net present worth cost for the selected remedy is $30.4 million (20 years
at 6%).
Utilization of Pennanent Solutions and Alternative Treatment Technolol!ies or Resource
Recoverv Technolol!ies to the Maximum Extent Practicable. The goal of the remedy selection
process is to select remedies that are protective of human health and the environment, that
maintain protection over time, and that minimize untreated waste. To meet this goal the
National Contingency Plan (40 CFR 300.430(a)(l» has established a number of expectations as
to the types of alternatives considered during remedy selection. For Landfills, these expectations
include:
.
Engineering controls, such as containment, for waste that poses a relatively low long-term
threat or where treatment is impracticable.
.
Institutional controls such as water use and deed restrictions to supplement engineering
controls as appropriate for short- and long-term management to prevent or limit exposure
to hazardous substances, pollutants or contaminants.
Page 43
-------
Record of Decision: Source Control Operable Unit - Landfills 8 and 10
In order to meet the goal and expectations outlined in the National Contingency Plan, the
following general remedial action objectives (RAO) are established for the principal media at the
SCOU:
Soil/Landfill Contents-- To prevent direct contact with and dermal absorption and ingestion
of the contaminated soils and landfill contents; control surface water runoff, ponding, and
erosion; to prevent or reduce infiltration and production of leachate; and to control dust
emissions to meet ambient air exposure criteria.
Landfill Gas-- To prevent inhalation of gases and the potential for explosion by controlling
landfill gases, and to meet ambient air exposure criteria.
Leachate/Leachate Seeps-- To prevent contaminants of interest in leachate from migrating
to surface waters and ground waters; to prevent dermal absorption and ingestion of this
leachate; and to reduce/eliminate on-site leachate generation.
Private Wells (Ground Water)-- To prevent ingestion, dermal absorption, and inhalation of
contaminants.
The selected remedy provides the best balance of tradeoffs among the alternatives with respect
to the nine evaluation criteria, in particular long-term effectiveness, reduction of toxicity,
mobility, or volume through treatment, short-term effectiveness, implementability and cost. The
remedy utilizes permanent solutions and alternative treatment technologies to the maximum
extent practicable. However, the NCP (40 CFR 300.430(a)(iii)(B» contains the expectation that
containment technologies will generally be appropriate remedies for wastes that pose a relatively
low-level threat or where treatment is impracticable. Containment has been chosen as the
response action at this site because:
.
The landfills are primarily composed of municipal, and to a lesser extent hazardous wastes;
therefore, they pose a low level threat rather than principal threat; and
.
The volume and heterogeneity of waste within the landfills make treatment impracticable.
Preference for Treatment as a Principal Element. Since the primary purpose of this remedial
action is Source Control of contaminants found on-site, treatment is not a principal element of
the selected remedy. However, treatment will be utilized for landfill gas and leachate emanating
from Landfills 8 and 10.
K. Documentation of Significant Changes
Two changes have occurred since the issuance of the proposed plan, as well as the public
meeting and comment period. These changes are:
.
.
Removal of Asphalt slabs from the unnamed tributary to Hebble Creek; and
Evaluation of the construction of a slurry wall at Landfill 8.
Both of these changes were generated from the results of the Off-Source Remedial Investigation
(OSRI) report.
Page 44
-------
Record of Decision: Source Control Operable Unit - Landfills 8 and 70
The OSRI report attributed P AHs in stream sediments to slabs of asphalt that were observed in
the unnamed tributary. Landfills 8 and 10 may also be potential sources of PAHs. The only
way the impact of Landfills 8 and 10 can be clearly demonstrated is to remove any asphalt slabs
as part of the selected remedy.
v
An evaluation of the feasibility of constructing a slurry wall will be conducted during the
Remedial Design. Updated hydrogeological in the OSRI for Landfills 8 and 10 not available at
the time of the Proposed Plan, indicate that a slurry wall may be suitable to reduce groundwater
flow through Landfill 8 by serving as a hydraulic cut-off at the west boundary of Landfill 8.
the groundwater flow component in this area is predominantly to the east, from the off-site
through landfill 8. Hydraulic cut-off at the west boundary could have the benefit of reducing
potential flow through the landfill and decreasing leachate volume and migration from the landfill
source. The required leachate treatment capacity and treatment time could subsequently be
reduced in the Remedial Design.
Three potential slurry wall configurations will be evaluated, with lengths of approximately 1100
feet (a linear wall), l600 feet (partially encircling) and 3200 feet (fully encircling), respectively.
The slurry wall will be assumed to be keyed into bedrock at a depth of approximately 50 to 100
feet. The Focused Remedial Investigation, Focused Feasibility Study, Off-Source Remedial
Investigation and Remedial Design Engineering Studies data will be utilized to conduct a three-
step evaluation of the slurry walls as outlined below:
Step 1 - Implementability: Surface and subsurface characteristics of the site will be evaluated.
The evaluation will consider site specific factors that may impact constnIctibility of a suitable
slurry wall, such as site topography, soils, and property access. If the slurry walls are
determined to be implementable or if the implementability is still uncertain, further evaluation
will be performed by proceeding to the second step.
Step 2 - Technical Effectiveness: An initial conceptual model of the relevant subsurface
hydrogeology in the area beneath and near Landfills 8 and 10 will be developed, based on
existing site information. Groundwater modelling will then be conducted to evaluate the
potential reduction of groundwater flux across Landfill 8 for the three lengths of slurry walls
under consideration. The initial run will include groundwater flux with no slurry wall to provide
a baseline for comparison with these three cases. All cases will assume installation of caps with
infiltration rates determined from the Focused Feasibility Study for Lanfills 8 and 10. Change
in flux from the baseline (no slurry wall) configuration will be measured to indicate any benefit
or gain attributable to the slurry wall component. These data will be carried to the third and
final step of the evaluation where a cost-benefit assessment is performed.
SteD 3 - Cost Benefit Assessment: A cost-benefit assessment will be performed utilizing
leachate treatment system costs from the Focused Feasibility Study for Landfllis 8 and 10, as
refined by the engineering studies performed during the Remedial Design, and slurry wall
construction costs from the USEPA, industry costing manuals, and vendor contacts. Estimated
capital costs and operation and maintenance costs for the leachate treatment system will be
included. From this assessment, one slurry wall configuration will be selected for further
evaluation in combination with various leachate extraction system schemes. Should a slurry wall
be found to be a cost effective addition to the remedy, it will be included in the design such that
it can be properly integrated with the cap construction phase of the Remedial Action.
Page 45
------- |